Res. Rep. Fac. Eng. Mie Univ., Vol. 29, pp. 73-120 (2004)

73

Abstracts of Doctor’s Thesises

Effect of “Topotactic” Reduction Products on Catalytic Activity ofMetallocene Catalyst for Olefin Polymerization
Satoru Yamada †(Department of Chemistry for Materials)
Keywords: Topotactic reduction, Tungsten disulfide, Molybdenum disulfide, Cocatalyst, Metallocene catalyst

1. Introduction
Metallocene catalysts, which consist of metallocene compounds and cocatalysts such as methylaluminoxane(MAO) or tetrakis(pentafluorophenyl)borate (B(C6F5)4-)-based salt, catalyze α-olefin polymerization to produce
polymers with a narrow molecular weight distribution and a narrow composition distribution.
The catalytically active species in the polymerization have been confirmed to be cationic metallocene
complexes with non-coordinating anions. The cocatalysts have been shown to convert neutral dialkylmetallocene(Cp2MR2) into the cationic monoalkylmetallocene (Cp2MR+) by way of protolysis or alkyl abstraction andprovide the cationic species with the non-coordinating anions [eq. (1)].
Cp2MR2 + [R3NH+][B(C6F5)4-] → [Cp2MR+][B(C6F5)4-] + RH + R3N(1)
Recently, we found that the salt of ammonium ion and anion obtained by “topotactic” reduction is asignificantly effective cocatalyst in metallocene catalyst for the ethylene polymerization [1]. The “topotactic”
reduction can be defined as the bulk reaction of an electronically conducting host lattice (Z) with vacant latticesites ( ) with electrons [eq. (2)].
(2)
xA+ + xe- + x[Z] → (A+)x[Z]xThe electrons are provided by concurrent chemical or electrochemical reactions and they enter into the
conduction band of the host lattice. At the same time with the uptake of the electrons, an equivalent amount ofmobile guest cation (A+) of electrolyte might diffuse from the host/electrolyte interface to the vacant lattice siteof the host lattice. Therefore, basic structural integrity of the host matrix is retained during the course of thereaction (topotactic process). The solid in the reduced state is shown as a macroanion matrix [Z]x- withintercalated mobile guest cation A+. Here, on the basis of the structural characteristics, the host lattice (Z) may be
divided into the following three kinds of categories: three-dimensional system, two-dimensional system, andone-dimensional system. To investigate the effect of “topotactic” reduction product on the catalytic activity ofmetallocene catalyst for olefin polymerization, we selected the two-dimensional systems as a host lattice with theaccommodation for alkyl ammonium ion such as N,N-Dimethylanilinium ion (Ph(Me)2NH+) that was one of
cations capable of effectively converting Cp2MR2 into the Cp2MR+ by protolysis.
The purpose of this thesis is to obtain an effective cocatalyst in metallocene catalyst for ethylene
polymerization. We synthesized a salt of Ph(Me)2NH+ and anion obtained by the “topotactic” reduction of thetwo-dimensional host lattice system such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) andinvestigated the effect of this salt on catalytic activity of a metallocene catalyst, and influences of the guest
cation content in the salt, the crystallite size of the salt, and the nature of anion obtained by the “topotactic”
reduction for the ethylene polymerization. Moreover, the ethylene/1-hexene copolymerization with these catalyst
systems was investigated.
—————————————————————————————————————————————†Catalysis and Polymerization Group, Yokkaichi Research Laboratory, TOSOH CORPORATION

74

Abstracts of Doctor’s Thesises

2. Results and Discussion
2-1. Effect of “topotactic” reduction product of MoS2 on catalytic activity of metallocene catalyst [2,3]We synthesized Ph(Me)2NH+ intercalated MoS2 and studied the effect of the compound on catalytic activityof metallocene catalyst and the influence of the Ph(Me)2NH+ content in the compound for ethylene
polymerization. In ethylene polymerization, addition of this Ph(Me)2NH+ salts to the bis(indenyl)zirconium
dichloride (Ind2ZrCl2)/triethylaluminum (Et3Al) catalyst improves the catalytic activity per mmol of Ind2ZrCl2
and the catalytic activity increases with increasing amount of the cocatalyst. Poly(ethylene) andpoly(ethylene-co-1-hexene) obtained with the metallocene activated by this cocatalyst have typical features suchas narrow molecular weight distribution and narrow composition distribution like as polymers obtained withconventional metallocene catalysts. So, we propose that Ph(Me)2NH+ in the interlayer space of MoS2, especiallyon the edges of layered structure of MoS2 would activate neutral dialkylmetallocene into cationicmonoalkylmetallocene by protonolysis and that the two-dimensional macroanions of MoS2 would act as
non-coordinating anions and supports for the obtained cationic species.
2-2. Effect of “topotactic” reduction product of WS2 on catalytic activity of metallocene catalyst [4,5]We synthesized Ph(Me)2NH+ intercalated WS2 and studied the effect of this compound on catalytic activityof metallocene catalyst and the influence of the crystallite size of this compound in ethylene polymerization incomparison with the above Ph(Me)2NH+ intercalated MoS2. In ethylene polymerization, addition of thisPh(Me)2NH+ intercalated WS2 to the Ind2ZrCl2/Et3Al catalyst enhanced drastically the catalytic activity incomparison to the Ph(Me)2NH+ intercalated MoS2, which had smaller crystallite size than the Ph(Me)2NH+
intercalated WS2. Poly(ethylene) obtained with the metallocene catalyst activated by addition of the Ph(Me)2NH+
intercalated WS2 has typical features such as narrow molecular weight distribution like polymers obtained withconventional metallocene catalysts, indicating that the active species of this catalyst system was the cationicmonoalkylmetallocene adsorbed on the edge site of the Ph(Me)2NH+ intercalated WS2. The Zr loadings on the
precipitate of the Ind2ZrCl2/Et3Al catalyst activated by the Ph(Me)2NH+ intercalated WS2 increased withdecreasing crystallite size of the Ph(Me)2NH+ intercalated WS2. However, the catalytic activity of the catalyst
decreased drastically with the decreasing crystallite size, indicating that the decrease of the crystallite size led tothe significant increase of inactive species for ethylene polymerization, probably the base-coordinated adducts.
3. Concluding remarksi) The salt based on anion obtained by the “topotactic” reduction of the two-dimensional host lattice system,
especially WS2 is a significantly effective cocatalyst in metallocene catalyst for ethylene polymerization.
ii) The catalytic activity of this metallocene catalyst system depends on both the Ph(Me)2NH+ content in theinterlayer space of this cocatalyst and the crystallite size of the cocatalyst.
Author’s publications[1] S. Yamada, A. Yano, US Patent 6372681 (2002).
[2] S. Yamada, A. Yano, M. Sato, T. Itoh, J. Mol. Catal. A, Chem. 200 (2003) 239-249.
[3] S. Yamada, A. Yano, M. Sato, Polymer Preprints, Japan Vol. 51, No. 8 (2002) 1595.
[4] S. Yamada, A. Yano, M. Sato, T. Itoh, J. Mol. Catal. A, Chem. in press.
[5] S. Yamada, A. Yano, M. Sato, Polymer Preprints, Japan Vol. 52 in press.

75

Abstracts of Doctor’s Thesises

A Study of Magneto-Optical Recording using a High Numerical
Aperture Lens and Short Wavelength Laser
Ariyoshi Nakaoki†(Department of Material Science)
Keywords: Magneto-Optic, High density, Numerical aperture, Wavelength, Spot size,
Sputtering, Noise level, Disk noise, Etching substrate, Reactive Ion Etching

1. Introduction
Because the recording density of an optical disc depends on the wavelength of the light source and thenumerical aperture (NA) of an object lens, it becomes very important what optical parameter is chosen. After thefist announcement of an optical video disk in 1972, the recording density of an optical disc has been improved
with shortening of the wavelength of laser and shifting NA of an object lens higher.
On the other hand, the magneto-optical (MO) disc was commercialized as a rewritable storage
medium for computer peripheral apparatus in 1988. The development for high density recording has beenachieved by adopting of a ZCAV system, a mark edge detection method, and a MSR (Magnetically Induced
Super Resolution) medium which used an exchange coupled magnetic multilayered films and the total capacityof disc amounts to 10 or more times as compared with that of a first product. In the MO disc, several approaches
for high density recording using a mean of a disc format or recording films have been reported, but very few
approaches having examined the optical parameter of wavelength and NA have been reported.
Then, the main purpose of this paper is discussion about the possibility of high density recording in
MO disc combined with a higher NA of objective lens and a shorter wavelength of a light source. As the 1st
research, (1) the effect of NA of 0.85 is argued in the point of view of recording density. Here, the significant
problem caused from the film stacking in the order of reverse or the reproducing of magneto-optical disc with alaser incidence from film side will be considered. Furthermore, the relationship between a small optical spot sizeby higher NA and a noise level during a reproducing is discussed. By 2nd research following it, (2) the shorter
wavelength of 405 nm is applied and the upper limitation of recording density is considered when laser device of
405 nm is combined with objective lens of NA 0.85.
2. Experimental conditions
Figure 1 shows the experimental set up for achieving aneffective NA of 0.85. The hemisphere lens made from quartz glassis assembled with keeping an optimum distance from theconventional objective lens of NA 0.6. The laser with wavelengthof 650 nm was used in order to evaluate an effect of high NA
optics and the laser of 405 nm is used for estimation of recording
density. The MO disc for measurement has an almost samestructure with a conventional disc. The recording film is deposited
on a glass 2P substrate in the order of reverse and consists of thefirst dielectric layer, magnetic double layer of GdFeCo and
TbFeCo materials, the thermal control layer of silver, the second
dielectric layer and the reflective layer of silver. These recording
films were covered by a polymer resin with thickness of 20 µm.
The carrier signals and modulated signal in (1, 7)-RLL code wererecorded on MO disc by magnetic field modulated (MFM) method.

Hemispherical lensDisc substrate

HolderObjective lensHolderFig. 1. A schematic drawing of the 2-elment
objective lens for high NA of 0.85.

3. Results and discussion
The noise level during reproducing a MO disc with NA 0.85 optics was measured and was comparedwith the case of NA 0.55. It was found that the noise level of NA 0.85 was worse than that of NA 0.55 and the† Sony Corporation

76

Abstracts of Doctor’s Thesises-5-40
Carrier

-60

-45
-50

-20
-55
-25
-60
-30
-65

-35
λ=407 nm
NA=0.6

-40
-45
0.1

-65

-70

∝ Ra1.5

-70
-75

1

Noise Level (dBm)

Noise
-15

Noise Level (dBm)

Carrier Level (dBm)

-10

10

-75
0.1

Read Power (mW)

Fig. 2. The reproducing laser power dependence ofcarrier level and noise level of MO disc.

0.2

0.3

0.4

0.5

Ra (nm)Fig. 3. The relationship between a surface roughness
Ra and a disc noise level.

2

Recording Density (Gbit/inch )Mark length & Track pitch (nm)differences were obtained 3 dB at mirror part of substrate, 5 dB at groove part, respectively. In order toinvestigate the cause of the noise increase, a reproducing power dependence of noise level was measured asshown in Fig. 2. The dependence of carrier level is also shown in this figure. It is obvious that the noise level issimply proportional to reproducing power, but the carrier level is not in the higher power region than 2.5 mW.
From this result, it is considered that a fluctuation of Kerr rotation angle which affects to the carrier level is not
the main cause of noise increase. We predict that the noise level is determined by the fluctuation of polarization
characteristic which depends on a laser incident angle at disc surface. The laser incident angle will be changed
easily by roughness of disc surface. Then, we investigated the relation between a surface roughness Ra and noiselevel. The surface roughness Ra is measured by the atomic force microscope (AFM). The result is shown in Fig.
3 and it is found that the noise level is proportional to the 1.5th power of Ra. Because the relationship between
the surface roughness of substrate and reproducing noise level was obvious, we could conclude that the maincause of reproducing noise was the fluctuation of polarization characteristic which was strongly concerned withthe disc surface roughness. It is also considered that the noise
will increase in the case of reproducing with higher NA
1000
objective because relative roughness will become large if spot
Track pitch
size becomes small. It becomes a significant problem as to highdensity recording by adopting a small laser spot. Therefore, inthis research, we adopted UV irradiation method as a
Spot Size
bit length100
pre-treatment method of disc, reactive ion etching (RIE) method
as a disc mastering process in order to create a low noise discwith a smooth surface. Consequently, it succeeded in improving
1/(Spot size)
Recording density
5dB or more of noise levels in a groove part. The read/write
performances on this improved disc were measured with several
10
NA0.85, 405 nm
optical parameters. The combination of NA (0.55, 0.85) andNA0.6, 405 nm
wavelength (655 nm, 405 nm) were used as optical parameters.
NA0.85, 650 nm
The performance of disc is estimated by its jitter value which
NA0.55, 685 nm (Aratani et al.)means the fluctuations of signal waveform with varying a
1
recording density. And then, the critical recording density is
0.1
1
determined according to a jitter criterion of 12.5 %. The
Spot size (0.8*λ/NA)
experimental results are shown in Fig. 4. It is clear that criticalFig. 4. The comparison of achieved recording
track pitch and bit length are proportional to the spot size which
density with several optical parameters.
is calculated with (0.8*wavelength/NA). It turns out inevitablythat recording density is proportional to the 1/2nd power of spot size. The maximum recording density of 20
Gbit/inch2 was achieved if the optical parameter of NA 0.85 and wavelength of 405 nm was used. This recording
density corresponds to 5 times of that in the case of NA 0.6 and wavelength of 650 nm, and it is considered to beappropriate from a viewpoint of an optical parameter.
2

5. Conclusion
The possibility of high density recording in MO disc combined with an objective lens of NA 0.85 anda short wavelength laser of 405 nm was evaluated. It is found that the disc noise caused by surface roughness
becomes significant if a small spot size of laser is used for reproducing an optical disc. Therefore, the low noise
disc with a smooth surface is the indispensable condition for high density recording combined with higher NAlens and shorter wavelength laser. We succeeded in making a low noise disc and could achieve a high density
recording of 20 Gbit/inch2 by adopting an objective lens of NA 0.85 and wavelength of 405 nm.

Abstracts of Doctor’s Thesises

77

Development Research of Novel Antioxidants
For Antiatherogenic Agent
Kunio Tamura†
Key Words: Antioxidants, Lipid Peroxyl Radical, LDL, Atherosclerosis, WHHL Rabbit, Antiatherogenic
Agent, Drug Design, Synthesis, Structure Activity Relationship, BO-653

1. Introduction
Recently, many lines of evidence, based on studies in cell culture and in experimental animal models,suggest that the oxidative modification of low-density lipoprotein (LDL) has a critical role in the development of
atherosclerosis. In this research, two types of antioxidants which prevent the oxidative modification of LDL were
designed, and the aim of this research is inventing a new antioxidant useful as an antiatherogenic agent inclinical from the structure activity relationship study.

2. Results and Discussion
2-1. Synthesis of Aniline-type Antioxidants and Their Antioxidant Activity
Since the amount of LDL metabolism via the scavenger receptor in a macrophage becomes less when theoxidative modification of LDL is prevented by antioxidants, the absolute quantity of native LDL will increase
theoretically. Therefore, the drug that prevents the oxidative modification of LDL and reduces plasma LDL byprevention of cholesterol biosynthesis is rational. The author focused attention on the antioxidant action of theaniline derivatives that are the related compound of phenol known as an antioxidant. Thus many types of aniline
derivatives that possess antioxidant activity and inhibitory effect on cholesterol biosynthesis were designed andsynthesized. From the consideration of their structure activity relationship, it was found that the aniline-type
derivatives were a quencher of superoxide radical (O2- ) which is one of the oxygen radicals. Since it is not clear
whether they are effective for prevention of atherosclerosis, the compound with the highest distribution to theblood of an atherosclerosis animal model was chosen and its antiatherogenic effect was investigated. However,the selected compound 1 was invalid in the animal model, although probucol, a selective antioxidant for a lipid
peroxyl radical, showed antiatherogenic effect. Thus it resulted in the conclusion that it is important to scavenge
a lipid peroxyl radical for effective inhibition of atherosclerosis progression.
OMe

R 1O
R2

R3
N

R4

Aniline derivatives†

Chugai Pharmaceutical Co., Ltd.

MeO
MeO

N
H

1

Abstracts of Doctor’s Thesises

78

2-2. Synthesis of Dihydrobenzofuranol-type Antioxidants and Their Antioxidant Activity
From the result of the aniline derivatives, the author started a new drug design for an ideal antioxidant bycompensating disadvantage of α-tocopherol, the most potent antioxidant in vivo. Then, the author hypothesizedthat the requirements as a LDL antioxidant would be possessing stronger antioxidant activity than α-tocopherol,demonstrating antioxidant activity in the core of LDL particle, and negating the character as a prooxidant which
α-tocopherol possesses. The author concluded that the rationally-designed new antioxidant should have thefollowing characteristics.
1) High hydrogen-donating activity and low prooxidant activity of its resulting radical intermediate
2) Localization inside the core of the LDL particle3) Sufficient delivery to LDL and vascular vessel wall
As a structure that can realize the above, the author performed the design and synthesis ofdihydrobenzofuranol derivatives, and succeeded in clarifying the strong antioxidant activity. Moreover, as thetechnique of evaluating the localization to LDL, the author succeeded in building the strategy for screening the
optimal LDL antioxidant by performing the oral administration using the WHHL rabbit that is a typical animalmodel for atherosclerosis. As the result of the above research, the author selected 4, 6-ditert-butyl-2,3-dihydro-2,2-dipentyl-5-benzofuranol 2 as an optimal compound, and clarified the potent LDL
antioxidant action as a clinical candidate for an antiatherogeic agent.

HO

R1
O R

2

Dihydrobenzofuranol derivatives

HOO

2 (BO-653)

3. Conclusions
In this research, the author performed the design and synthesis of the aniline derivatives and thedihydrobenzofuranol derivatives as new antioxidants, and showed the structure activity relationship of theirantioxidant activities. Moreover, the author showed that 2 (BO-653) possesses the potent antioxidant activity
which is required for an effective antiatherogenic agent. BO-653 is a promising candidate as a newantiatherogenic agent in clinical. The author expects that the potential of antioxidants to cardiovascular diseases
like atherosclerosis is clarified by the clinical trial currently performed in the U.S.

Author’s Publications[1] Tamura, Kunio; Kato, Yoshiaki; Ishikawa, Akira; Kato, Yasuharu; Himori, Motomu; Yoshida, Mitsutaka;Takashima, Yoshiaki; Suzuki, Tsukasa; Kawabe, Yoshiki; Cynshi, Osamu; Kodama, Tatsuhiko; Niki, Etsuo;
Shimizu, Makoto, Design and synthesis of 4,6-di-tert-butyl-2,3-dihydro-5-benzofuranols as a novel series ofantiatherogenic antioxidants. J. Med. Chem. 2003, 46, 3083-3093.
[2] Tamura, K.; Kato, Y.; Ishikawa, A.; Kato, Y.; Himori, M.; Yoshida, M.; Cynshi, O.; Higashida, A.; Aono,
R.; Ohba, Y., Design and synthesis of novel dihydrobenzofuranol antioxidants. Book of Abstracts, 214th
ACS National Meeting, Las Vegas, NV, September 7-11 (1997), MEDI-218.
[3] Tamura, K.; Kato, Y.; Yoshida, M.; Cynshi, O.; Ohba, Y., Preparation of 4-alkoxy-2,6-di-t-butylphenol
derivatives as antiarteriosclerotic agents. WO94/08930.
[4] Kato, Y.; Tamura, K.; Ohba, Y.; Kawabe, Y.; Cynshi, O., Preparation of aniline derivatives as low-density
lipoprotein inhibitors. WO91/11994.

Abstracts of Doctor’s Theses

79

Surface properties of inorganic/organic hybrids prepared bysol-gel method and application to novel heat-resistant materials
Takuya Shindou†
Keywords: sol-gel, organic/inorganic hybrid, polydimethylsiloxane, PDMS, surface morphology,
AFM, electrical insulation, thermal conductivity, heat-resistance
1.Abstract
Polydimethylsiloxane(PDMS)-based inorganic/organic hybrid films were prepared by sol-gel method usingsilanol-terminate PDMS and metal alkoxide as starting materials. Surface morphology of the hybrids was
examined in terms of contact angle of water and a tapping-mode Atomic Force Microscopy (AFM). A phaseseparation of hydrophilic and hydrophobic areas appeared on the surface of the hybrid films heat-treated at
150℃. The phase separation disappeared with increasing heat-treated temperature. The hybrid film heat-treatedat 300℃ shows a homogeneous surface and indicates a relatively high contact angle of water, 〜115° The
PDMS-based hybrid film exhibited an excellent toner peeling capability, suggesting its practical use in thexerographic printers. Electrical and mechanical properties of PDMS-based inorganic/organic hybrids have beenstudied. The PDMS-derived hybrid shows an excellent electrical insulation property of more than 1010Ω・m evenat 200℃. By mixing filler with the hybrid sol, a functionalized sheet could be made. The hybrid mixed withaerosil and boron nitride yields a good mechanical property and the hybrid mixed with alumina shows a highthermal conductivity beyond 5 W/m・K. The hybrids are expected to have potential for heat-resisting electricalinsulating materials.
2.Introduction
In the field of electro-photographic printing, the demand for a higher quality and speedy print has increased.
It requires to replace traditional components with good performance ones for that purpose. The author has been
making an effort to apply inorganic/organic hybrids to xerographic printer component, with the expectation thatthe property of those hybrids can be controlled by tailoring the nanostructure. The PDMS-based hybrids have not
only properties such as flexibility and thermal stability1)-4) but also potential for water-repellency as expectedfrom the nature of dimethylsilicon units. The structure and mechanical properties of PDMS-based hybrids havebeen clarified by various research papers5)-7), however, there are very few studies on shortening the film
preparation and controlling the surface properties. They are important factors when applied to the material of
xerographic components. In this work, the effect of heat-treatment temperature and inorganic/organic molar ratioon the film surface properties was examined. Furthermore, the evaluation of applicability of the hybrid to thepractical use was carried out in terms of the so-called “toner offset.”In addition to the capability as a thermal-fixation roll of xerographic printer, PDMS-based hybrids havegreat potential for novel electrical insulating materials because the hybrids have the good properties ofheat-resisting, electrical insulating and elasticity. Recently, heat generation from central processing units is
rapidly getting large because the electronics device is moving into downsizing and high-speed processing. The
demand of heat-resistive electronic materials in high temperatures is increasing. The electrical properties such asvolume resistivity, relative permittivity and loss tangent of the hybrid sheets were examined up to 200℃.
Because a lot of fillers can be introduced into the hybrid sol, functionalized hybrid sheets have developed in thiswork. The thermal conductivity and mechanical properties of the hybrid sheet were examined.
3.Surface properties of TIP(Ti-isopropoxide)-PDMS-based
inorganic/organic hybrid
The PDMS-based hybrids have a smooth surface about
10nm level. The phase images of hybrid films by AFM are
shown in Fig.1. The films were prepared by changing themolar ratio of PDMS to TIP from 0.2 to 0.35 and heat-treatedat 150℃. It can be seen that the image changes for the molar

PDMS/TIP=0.2

PDMS/TIP=0.3

PDMS/TIP=0.35

Fig. 1. Phase image of AFM for PDMS-based
hybrids heat-treated at 150℃.

† Advanced Technology Research and Development Division, Suzuka Fuji Xerox Co., Ltd.,

80

Abstracts of Doctor’s Thesises

ratio; in the case of the low ratio of 0.2, separated continuous two domains are observed and they change into aclear island-shaped spot when the molar ratio increases. The spots are considered to be more hydrophilic than therest or matrix region and to be rich in titania or TIP species leading to a large contact angle of water withincreasing the molar ratio. The phase images of the hybrid films heat-treated at 300℃ exhibit a featureless or
homogeneous surface at any PDMS/TIP ratio and the films show a hydrophobic surface property.

5.PDMS-based inorganic/organic hybrid sheet and functionalization
Figure 3 show the appearance of ZTP(Zr-propoxide)-PDMS-based
hybrid sheet. It has been also found that the sheet is very heat-resistive.
By mixing filler with the hybrid sol, a functionalized sheet can be made.
Zr tetra-propoxide (ZTP)-PDMS-derived hybrid mixed with aerosil andboron nitride yields a good mechanical property and the hybrid mixed
with alumina shows a high thermal conductivity beyond 5 W/m・K.
6.Conclusion
The surface morphology of PDMS-based inorganic/organic hybrid
films has been examined. These results give a promising application of
PDMS-based hybrids to novel parts of the xerographic printer. And the
hybrid mixed with functionalizing fillers shows high potential forheat-resisting, thermal conducting and electrical insulating materials.

■：at RT ●：200℃
16

log ρ / Ω･m

4.Electrical properties of TIP-PDMS-based inorganic/organic hybrid
Figure 2 shows the volume resistivity of the TIP-PDMS-based
hybrid films at room temperature and 200℃. The hybrid films show an
excellent electrical insulation property of more than 1010Ω・m even at
200℃. The properties of relative permittivity (εr’) below 5 and the loss
tangent (tanδ) below 4×10-4 at 200℃, suggesting that the hybrid has highpotential for electrical insulating material. It has been found that thedependence of dielectric properties on temperature (room temperature to250℃) or frequency (40Hz to 400kHz) of the hybrid film shows no signof dielectric relaxation.

14

12

10
0.2

0.4

0.6

0.8

PDMS/TIP molar ratio
Fig. 2. Change of volume resistivity
of hybrid for the molar ratioof PDMS to TIP.

Fig. 3. Appearance of ZTP-PDMSbased hybrid sheet.

7.References
1) H. Shmidt, New Type of Non-Crystalline Solids between Inorganic and Organic Materials, J. Non-Cryst.
Solid, 73, pp.681-191 (1985).
2) G. L. Wilkes, B. Orler and H. Huang, Ceramer : Hybrid Materials Incorporating Polymeric/OligomericSpecies into Inorganic Glasses utilizing a Sol-Gel Approach, Polym. Prep., 26[2], pp.300-302 (1985).
3) H. Huang, B. Orler and G. L. Wilkes, Structure-Properties Behavior of New Hybrid Materials Incorporating
Oligomeric Species into Sol-Gel Glasses.3. Effect of Acid Content, Tetraethoxysilane Content, andMolecular Weight of Poly(dimethylsiloxane), Macromolecules, 20[6], pp.1322-1330 (1987).
4) Y. J. Chung, S. –J. Ting and J. D. Mackenzie, “Rubbery Ormosils”; pp.981-986 in Better Ceramics ThroughChemistry IV, Proceedings of the Materials Research Society Symposium 180 (San Francisco, CA, April
1990). Edited by B. J. J. Zelinski, C. J. Brinker, D. E. Clark, and D. R. Ulrich. Materials Research Society,
Pittsburgh, PA, (1990).
5) J.D. Mackenzie, Q. Huang, and T. Iwamoto, Mechanical Properties of Ormosils, J.Sol-Gel Sci. and Tech. 7,
pp.151-161 (1996).
6) J.D. Mackenzie, J.Sol-Gel Sci. and Tech., Structures and properties of ormosils, 2, pp.81-86 (1994)
7) S. Katayama, Y. Kubo and N. Yamada, Characterization and Mechanical Properties of Flexible
Dimethylsiloxane-Based Inorganic/Organic Hybrid, J. Ceram. Soc. 85(5), pp.1157-1163 (2002)．
Author’s Publications[1] T. Shindou, S. Katayama, N. Yamada and K. Kamiya, Surface properties of Polydimethylsiloxane-Based
Inorganic/Organic Hybrid Films Deposited on Polyimide Sheets by the Sol-Gel Method, J.Sol-Gel Sci. andTech., 27, pp.15-21 (2003)[2] T. Shindou, H. Konishi, S. Nakamura and K. Kamiya, ZTP-PDMS derived organic/inorganic hybridmaterials, TECHNICAL REPORT OF IEICE., OME2003-102(2003-11), SHINGAKUGIHOU, Vol.103,
No.441 , pp.25-29 (2003)

Abstracts of Doctor’s Thesises

81

Study on Spontaneous Polymerization Mechanismof Electron-accepting Substituted Quinoid Compoundswith Electron-donating Vinyl Monomers
Yukihiro Mitsuda(Polymer Synthesis Lab., Division of Material Science)
Keywords: Polymerization Mechanism, Electron-Accepting Quinoid Compounds,
Electron-donating Vinyl Monomers, Gauche- and Trans-form Zwitterionic Intermediates

Introduction
Spontaneous reactions of electron-accepting olefin monomers with electron-donating ones gavealternating copolymers and/or homopolymers. To explain these spontaneous reactions, Hall and coworkers
have proposed the “bond-forming initiation theory”, where tetramethylene intermediates, which are diradicalor zwitterionic depending on the nature of the substituents on the olefins, are formed between
electron-accepting olefins and electron-donating ones, and diradical intermediate leads to an alternating
copolymer and the zwitterionic one leads to a homopolymer. This theory has been extended to thespontaneous reactions of diolefins and quinoid compounds. Previously, Iwatsuki et al. reported thatspontaneous reaction of symmetrically electron-accepting substituted quinoid compound,
7,7,8,8-tetracyanoquinodimethane (TCNQ), with electron-donating vinyl monomer, styrene, proceeded via
diradical intermediate to give alternating copolymer. In this work, spontaneous reactions of unsymmetrically
substituted quinoid compound, 1-(2,2-dimethyl-1,3-dioxane-4,6-dione-5ylidene)-4-(dicyanomethylene)-2,5cyclohexadiene (QM-1) with electron-donating vinyl monomers, p-, α- and β-substituted styrenes (RSt: R =pOMe, pMe, pH, pAcO, pCl, pCOOMe, pCN, αMe, αPh, βMe, βPh), butyl vinyl ether (BVE) and2-methylene-1,3-dioxepane (MDOP) were investigated to elucidate reaction mechanism.
Experimental Section
A given amount of QM-1 and chloroform were placed in a glass ampoule, and into the resulting
solution was added a solution containing a given amount of electron-donating vinyl monomers in chloroform.
After stirring at a given temperature for a given hour, the reaction mixture was poured into a large amount of
hexane to deposit a polymeric product as a hexane-insoluble fraction. The polymeric product was purified bydissolution-reprecipitation method using chloroform as a solvent and hexane as a precipitant, respectively,
and dried under reduced pressure until the constant weight was attained. The supernatant was placed under
reduced pressure to remove a solvent and give a residue as a hexane-soluble fraction, which was dried under
reduced pressure until the constant weight was attained. The polymeric and residual products werecharacterized by 1H NMR, 13C NMR and IR spectroscopies, GPC, and elemental analysis.
Results and Discussion
Spontaneous Reaction of QM-1 with pMeOSt
The polymer obtained as a hexane-insoluble fraction was determined to be random copolymer oftrisbstituted quinodimethane, 7-(4-methoxyphenyl)-8,8-dicyanoquinodimethane, and QM-1 units. On theother hand, residual product obtained as a hexane-soluble fraction was to be unreacted QM-1 and one-to-one
cycloadduct (Cycloadduct) of methylene Meldrum’s acid (MM) and pMeOSt. To obtain some information

82

Abstracts of Doctor’s Thesises

about the reactive intermediate formed in the system, the spontaneous reactions of QM-1 with pMeOSt in thepresence of TEMPO as radical inhibitor or methanol as ionic one were investigated. In the presence of
TEMPO, the copolymer yield and molecular weight were lower compared with the corresponding one
obtained in the absence of TEMPO. These results indicated that the copolymer obtained as ahexane-insoluble fraction was formed by radical mechanism. In the presence of methanol, one-to-one-to-one
adduct of QM-1, pMeOSt, and methanol was isolated. This strongly indicated that a zwitterionic intermediate
was formed in spontaneous reaction of QM-1 with pMeOSt. On the basis of these results, the mechanism for
spontaneous reaction of QM-1 with pMeOSt was proposed as shown in Scheme that the cyclobutane ring wasformed via gauche-form zwitterionic intermediate, and then it cleaved via metathesis process to generate
QM-2 and MM, the former of which copolymerized with QM-1 to give a random copolymer and the latter ofwhich reacted with pMeOSt to form Cycloadduct.
Spontaneous Reactions of QM-1 with BVE and with MDOPIn spontaneous reaction of QM-1 with BVE, the polymer obtained as a hexane-insoluble fraction wasdeterminedtobearandomterpolymer
consistedoftrisubstituted
quinodimethane,
7-butoxy-8,8-dicyanoquinodimethane (QM-2), QM-1, and BVE units. The hexane-soluble product was to be
one-to-one cycloadduct of MM and BVE. These results indicated that the mechanism for spontaneous
reaction of QM-1 with BVE was similar to QM-1/MeOSt system. On the other hand, in spontaneous of QM-1
with MDOP, the polymer was an alternating copolymer of QM-1 and MDOP. This result was different fromone of QM-1/BVE system. Thus, it suggested that the substitution mode of comonomer influenced toreaction mechanism, that is, as MDOP is α,α-disubstituted olefin, no cyclobutane ring was formed, and thenisomerization to trans-form zwitterionic intermediateO
took place.
NC
O+

Spontaneous Reactions of QM-1 with RSt
For the uses of pCOOMeSt, pCNSt, αPhSt, andβPhSt, no spontaneous reaction occurred because of
weaker electron-donating or more bulky vinyl
monomers. Spontaneous reaction of QM-1 with
αMeSt gave an alternating copolymer. This result wassame one of QM-1/MDOP system. In the case of RSt(R = pMe, pH, pOAc, pCl, βMe), the obtained
polymers were determined to be random terpolymer
including trisubstituted quinodimethane (QM-2) unit.
As these results, the reaction mechanism was affectedby the nature, bulkiness, and position of substituent.

NC

D

O
O
QM-1

O

NC

electron-donating
vinyl monomer

O
O
O

NC

O

O
O

NC

D
gauche

NC

O

O

NC

D

trans

O
O

O

O

NC

O

O

NC

O

NC

D

D

Conclusions
Spontaneous reactions of quinoid compoundswith electron-donating vinyl monomers were
investigated. It was found that polymerization
proceeds via zwitterionic intermediate, which existed
in gauche or trans-forms, the former of which gave arandom copolymer and the latter of which gave analternating copolymer.

O
NC

O

H

alternating copolymer

+
NC

D

O
O

QM-2

vinyl monomer

MM

QM-1
and/orvinyl monomer

O

O
O
O

random copolymer
D

Cycloadduct
SchemeAuthor’s publications
1) Y. Mitsuda, T. Fujikawa, T. Uno, M. Kubo and T. Itoh, Macromolecules, 2003, 36, 1028.
2) Y. Mitsuda, S. Kawaguchi, T. Uno, M. Kubo and T. Itoh, Macromolecules 2004, 37, 1251.
3) S. Kawaguchi, Y. Mitsuda,, T. Uno, M. Kubo and T. Itoh, Kobunshi Ronbunshu in press
4) Y. Mitsuda, T. Fujikawa, K. Nakasaka, T. Uno, M. Kubo and T. Itoh, J. Polym. Sci. Part A Polym. Chem.
to be submitted.

83

Abstracts of Doctor’s Thesises

Study on AlN epitaxial films grown by MOVPE method andtheir applications
Tomohiko Shibata †Keywords: AlN, III-V nitride, MOVPE, Crystal Quality, Dislocation, SAW

1. Introduction
Al-rich III-V nitrides have a great potential for future optical devices in ultraviolet region,
including light emitting diodes (LEDs), laser diodes (LDs) and photodetectors, due to their wideband gap. In particular, AlN has piezoelectricity and the widest direct band gap (6.2eV) of the
III-V nitride materials, so that the realization of high-quality AlN epitaxial films can widelyextend application fields of III-V nitride materials. So far, fewer researches on AlN epitaxial
growth have been reported than on GaN epitaxial growth due to large difficulties in AlN growth.
In this study, I realized high-quality AlN epitaxial films on several single-crystalline substrates
using a metal organic vapor phase epitaxy (MOVPE) method and I made it clear that the AlN
epitaxial films had great potentials for various applications including optoelectronic devices,
electronic devices and surface acoustic wave (SAW) devices.
2. Application for optoelectronic and electric devices(0001)-faced AlN epitaxial films on (0001)-faced sapphire or 6H-SiC substrates arepromising as templates for the AlGaN growth that can be applied to wide range of semiconductor
devices.
First of all, I achieved crackless high-quality AlN epitaxial films with an atomically flat
surface on both substrates as shown in Fig.1. It is characteristic features that the AlN epitaxial
films have narrow X-ray rocking curve (XRC) profiles for (0002) plane with full width at half
maximum (FWHM) values equal to less than 100 arcsec. A dislocation density of the AlN
epitaxial films is as low as 1x10 1 0 /cm 2 , which is a lower value than ever reported, and most of
dislocations consist of edge-type ones[1,2].
Next, I found the effect of AlN templates for AlGaN growth. The overgrown AlGaN films
have no cracks in all AlN molar fraction range. XRC FWHM values for (0002) plane of the
AlGaN epitaxial films are equal to less than 200 arcsec, which is least values ever reported[3,4].
In the case of an overgrown GaN film, in particular, its dislocation density reaches as low as
GaN

AlN

Sapphire

1µ m

Fig. 1 AFM surface image of AlN filmin the region of 5x5µm on sapphire.
†

NGK INSULATORS, ltd.

Fig. 2 Bright-field Cross-section TEM image.

84

Abstracts of Doctor’s Thesises

4x10 8 /cm 2 and a dislocation density dropped by less than a tenth from AlN to GaN as shown in
Fig.2[5,6]. It is thought that the phenomena of the restraint of crack generation and the drastic
reduction of dislocations are caused by a compressive stress due to larger in-plane lattice
constants of the overgrown AlGaN layer than that of the underlayer AlN.
The improvement of crystal qualities of the overgrown AlGaN results in improving somedevice performances, such as luminous efficiency of LEDs, electronic properties of HEMT
devices and so on.
3. Application for SAW devices
In order to realize SAW devices, a (11 2 0)-faced AlN epitaxial film on a (10 1 2)-faced
sapphire substrate is the most promising combination due to its modest electromechanicalcoupling coefficient (1%) and its high SAW velocity (6000m/sec). Therefore, the AlN/sapphire isa promising candidate for SAW devices operating in a GHz band, which is required for current
wireless communication systems. However, there have been remained some problems to degrade
crystal qualities of the AlN film, for instance, inverted twins which caused a reduction of thevalue of electromechanical coupling coefficient. Systematic optimization of the growth
conditions of the AlN was carried out during MOVPE in order to extract the above-mentioned
potential properties.
The use of off-angle (10 1 2)-faced sapphire substrates, in which the surface plane was tilted
towards [1 1 01] sapphire direction, was shown to effectively restrain the generation of theinverted twins. The results of AlN grown on a round-shaped (10 1 2)-faced sapphire support that
an off angle with specific direction is effective in improving crystal qualities as well as
restraining inverted twin[7,8]. Furthermore, SAW filters at 2.4GHz packaged into 5x7mm size
were reliably realized using the optimized AlN on the off-angle sapphire substrates[9].
4. Conclusion
High-quality AlN epitaxial films were realized using MOVPE method on a (0001)-faced
sapphire, a (0001)-faced 6H-SiC substrates and a (10 1 2)-faced sapphire. As a result, potentials
of AlN can be extracted and it is found that the AlN epitaxial films are useful for templates ofhigh-quality AlGaN growth and substrates for SAW devices.
Author’s publications[1] T. Shibata, K. Asai, T. Nagai, S. Sumiya, M. Tanaka, O. Oda, H. Miyake and K. Hiramatsu;
Materials Research Society Symposium Proceedings, Vol. 693 (2002) 541.
[2] T. Shibata, K. Asai, S. Sumiya, M. Mouri, M. Tanaka, O. Oda, H. Katsukawa, H. Miyake and
K. Hiramatsu; Phys. Stat. Sol (c) Vol. 0 No. 7, (2003) 2023.
[3] Y. Kida, T. Shibata, H. Naoi, H. Miyake, K. Hiramatsu and M. Tanaka; Phys. Stat. Sol. (a)Vol. 194 No. 2, (2002) 498.
[4] Y. Kida, T. Shibata, H. Miyake and K. Hiramatsu; Jpn. J. Appl. Phys. Vol. 42 (2003) L572.
[5] T. Shibata, Y. Kida, H. Miyake, K. Hiramatsu, Y. Hori, K. Asai, T. Nagai, S. Sumiya, M.
Tanaka and O. Oda; Compound Semiconductors 2001 (Inst. Phys. Conf. Ser. No. 170) 795.
[6] T. Shibata, Y. Kida, H. Miyake, K. Hiramatsu, K. Asai, T. Nagai, S. Sumiya, M. Tanaka and O.
Oda; Materials Research Society Symposium Proceedings, Vol. 693 (2002) p.219.
[7] T. Shibata, K. Asai, Y. Nakamura, M. Tanaka, K. Kaigawa, J. Shibata and H. Sakai; Journalof Crystal Growth Vol. 229 (2001) 63.
[8] T. Shibata, Y. Hori, K. Asai, Y. Nakamura, M. Tanaka, K. Kaigawa, J. Shibata and H. Sakai;
IPAP Conf. Series Vol. 1, (2000) 981.
[9] T. Shibata, Y. Hori, K. Asai, Y. Nakamura, M. Tanaka, K. Kaigawa, J. Shibata and H. Sakai;
2000 IEEE Ultrasonics Symposium Proceedings, (2000) 287.

85

Abstracts of Doctor’s Thesises

The improved component materials using Rare Earths for SOFCs
through the newly devised synthesis process and chemicalcomposition.
Eisaku Suda †(Materials Science)
Keywords: Sintering Characteristics, Coprecipitation, Rare Earth, Cerium Oxide, SOFC

Abstract

Relative density [%]Convecopr ntional
ecipi
tatio
Solid
n
state
react
ion

ss

New
proc
e

Relative density [%]In this study, the synthesis process and chemical composition were investigated mainly in order toprepare the appropriate component materials using Rare Earths for SOFCs. Then the physical properties andsome advantages have been clarified here.
(a) 100
For electrolyte, the low-temperature sinterable RE-doped
ceria powders (fluorite) has been developed using a newly-devised90
heat-treatment process in the coprecipitation method. This powder
shows the lowest value in the reported sintering temperatures of rareearth metal-doped ceria powders: Relative densities ≥ 94%, where
80
sintered ceramics can provide gastightness, was attained for this new
powder after heating at temperatures ≥ 1000°C (Fig.1). To lower
70
densely-sintered temperature, use of sintering aids is undesirable
because such aids may damage other cell components. The present
60
low-temperature sintering characteristics of the electrolyte without
1000 1200 1400 1600
sintering aids are quite attractive in view of the problems associatedtemperature [℃](b) 100
with the SOFC fabrication process.
The crystal structure, sintering characteristic, electrical
90 1100℃
conductivity and thermal expansion of GdxTi2O7-δ pyrochlores (1.72
1000℃≤ x ≤ 2.10) have been measured and discussed as electrolytes in the80
high-temperature solid oxide fuel cells. These materials showed the
900℃
indication of structural disorder with increasing A-site deficiency.
70
Sintering characteristics of the pyrochlores promoted by A-site
60
deficiency. The pyrochlores showed linear thermal expansion
behavior in air and in the H2 atmosphere, and with increasing A-site
50
deficiencies, their TEC values decreased and were close to that of0
5
10
YSZ electrolyte. The electrical conductivity of these materials was
Holding time [h]slight lower than acceptable as the electrolyte in SOFC with highFig.1 (a) Relative density of theperformance. In addition, the A-site deficiency in the pyrochlores
Ce0.9Gd0.1O1.95 (CGO) powders as afunction of temperature, where thecaused an appearance of electronic conduction at high temperatureholding time at the highest
under the reducing atmospheres. Thus, this problem remains to betemperature is 2h. (b) Relativesolved. From the viewpoints of these properties, when it isdensity of new CGO as a function ofholding time with a parameter of† ANAN KASEI CO.,LTD.
heating temperature.

86

Abstracts of Doctor’s Thesises

considered the GdxTi2O7-δ pyrochlores for use as an electrolyte in the high-temperature SOFC, an enhancementof their electrical conduction for oxide-ion and a prevention of their electronic conduction at high temperatures
under reducing atmospheres are necessary.
For anode, the preparation process and anodic properties for NiO-CGO powder were studied. Single
cell tests on SOFC with anodes made from various NiO-CGO powders showed that anode polarization for spray
dry was lowest. Overall, NiO-CGO prepared by spray dry (SD) gave the best result. SD as a starting powder
had narrow particle size distributions. The Ni and CGO particles in the microstructure of SD showed
good-connections between Ni-Ni, CGO-CGO and Ni-CGO particles were formed in the anodes. The
appropriate Ni content in this system should be investigated in order to lower the sintering temperature of anodebecause NiO particles could prevent the sintering of HT-CGO particles.
For current collector, the properties of the La0.6AE0.4MnO3 perovskites and La0.6AE0.4MnO3-Mn3O4
composites (AE = Ca and Sr), have been evaluated as potential electric current collectors between the cathodeand the interconnect in the high-temperature SOFC. The results can be summarized as follows; For
La0.6AE0.4MnO3 perovskites, La0.6AE0.4MnO3 perovskites are not appropriate as electrical current collectors,
because of a large difference in TECs between La0.6AE0.4MnO3 and YSZ. For La0.6AE0.4MnO3-Mn3O4
composites, (1) The TECs of the composites approached that of YSZ electrolyte at around 50 vol% Mn3O4, andthe dense composites showed no anomalous thermal expansion behavior. (2) The manganese oxide addition
greatly enhanced the sintering characteristics of the perovskites. It can be concluded that the dense
La0.6AE0.4MnO3–Mn3O4 composites are appropriate as potential electric current collectors in thehigh-temperature SOFC.
For interconnector, Li-doping of La1-xSrxCrO3 was an effective way of enhancing the sinteringcharacteristics. The fine powders made by the Pechini method showed lower sintering characteristics when
they were compared to those made by the solid-state technique. The solubility limit of Li element decreases
with increasing Sr-content in the perovskites. Although the TECs of Sr-doped lanthanum chromites should becontrolled by Sr-content, there is a serious problem in the fact that Sr cannot be included as solid solution at
higher concentration. Improvements of TEC control and sintering have to be achieved for using as a separator
of SOFC.
So many materials and fabrication methods for SOFC have been investigated in these thirty years.
There, however, still remain many problems to be solved to obtain a high performance for SOFCs. The resultsof this work would inspire the future research and developments of SOFCs.
Author’s publications(1) Rhodia Electronics & Catalysis and Anan Kasei ; from a leadership in high purity rare earth compounds to aleadership in high performance rare earth based products., P. Macaudiere, B. Pacaud and E. Suda, Rare Earths,
39(2001)71-76.
(2) Low-temperature sinterable Ce0.9Gd0.1O1.95 powder synthesized through newly-devised heat-treatment in the
coprecipitation process, E. Suda, B. Pacaud, Y. Montardi, M. Mori, M. Ozawa and Y. Takeda, Electrochemistry,
71[10](2003)866.
(3) Electrical and thermal properties of dense Ce1-xRExO2-δ electrolyte using low-temperature sinterable powder(0 ≤ x ≤ 0.2, RE=Y, Sm, Gd), E. Suda, B. Pacaud, Y. Montardi, M. Mori, and Y. Takeda, Material ResearchSociety of Japan, in press.
(4) Compatibility of GdxTi2O7 pyrochlores (1.72 ≤ x ≤ 2.0) as electrolytes in high-temperature solid oxide fuelcells, M. Mori, G. M. Tompsett, N. Sammes, E. Suda and Y. Takeda, Solid State Ionics, 158(2003)79-90.
(5) Microstructure and anodic properties of Ni-Ce0.9Gd0.1O1.95 (CGO) cermets using sinterable CGO powder, E.
Suda, B. Pacaud, Y. Montardi, M. Itagaki, S. Ohara and Y. Takeda, American Ceramic Society, in press.
(6) Application of La0.6AE0.4MnO3 (AE=Ca and Sr) to electric current collectors in high-temperature solid oxide
fuel cells, M. Mori, N. M. Sammes, E. Suda and Y. Takeda, Solid State Ionics, 164(2003)1-15.
(7) Sintering characteristics and thermal expansion behavior of Li-doped lanthanum chromite perovskites
depending upon preparation method and Sr doping, E. Suda, B. Pacaud, T. Seguelong and Y. Takeda, Solid State
Ionics, 151(2002)335-341.

Abstracts of Doctor’s Thesises

87

Life evaluation and improvement of performance of materials in
Solid Oxide Fuel Cell
Masatoshi Hattori†(Department of Chemistry for Materials)
Keywords: SOFC, Monte Calro Simulation, Yttria Stabilized Zirconia, Raman spectra

1. The purpose
Solid oxide fuel cells (SOFCs) have been attracting great attention as a promising new method forelectrical power generation. SOFCs can provide high total efficiency when used in a cogeneration systembecause their high operating temperature such as 1000ºC gives the advantage of producing high-temperature
discharge gases. They also promise clean power with little NOx emissions. The basic unit of a cell consists of athree-layer structure: anode, electrolyte, and cathode. It is necessary to achieve not only higher performance but
also a more stable cell in order to apply SOFCs for practical use, because SOFCs must operate for tens of
thousands of hours to be practical. The aim of this research is life evaluation and improvement of performanceof materials in SOFCs.
2. Life evaluation of materials of cathode (fuel electrode)Life evaluation of Ni-YSZ (Yttria Stabilized Zirconia) used for fuel electrode was examined. Not only
aging performance test, but also Monte Calro Simulation (MCS) method was used. Grain growth of Ni is
controlled, so that the particle diameter of YSZ remains small. The grain growth ratios of Ni/YSZ predicted byour simulations are in good agreement with experiment. The particle diameter ratio of nickel to YSZ needs to be
3 or greater. This research is applicable to the optimization of porosity and interfaces in other triple phasesystems.
3. Life evaluation of materials of electrolyte
The electrical conductivity change with annealing at 1000ºC in the Y2O3-ZrO2 (YSZ) system was
examined. Among the sintered samples doped with 8.0mol%Y2O3 (8.0YSZ), 8.5mol%Y2O3 (8.5YSZ),
9.0mol%Y2O3 (9.0YSZ), 9.5mol%Y2O3 (9.5YSZ) and 10.0mol%Y2O3 (10.0YSZ), 9.5YSZ and 10.0YSZ showed
no conductivity decrease even for the annealing period of 1000 h, while 8.0YSZ and 8.5YSZ showed significant
decrease with time although the initial conductivities were higher than those of 9.5YSZ and 10.0YSZ. 9.0YSZ
showed only slight conductivity decrease. The measurement of Raman spectra demonstrated that thedeterioration in conductivity related to the gradual formation of fine tetragonal phase in the cubic phase.
Consequently, 9.5YSZ was seemed to be optimum as the electrolyte material of solid oxide fuel cells from thepoint of stability in high conductivity.

†Chubu Electric Power Company, Inc.

88

Abstracts of Doctor’s Thesises
0.18
8.0YSZ
8.5YSZ
9.0YSZ
9.5YSZ
10.0YSZ

Conductivity(S/cm)

0.16

0.14

0.12

0.1

0.08
0

200

400

600

800

1000

1200

Time(h)Time dependence of conductivity of YSZ annealed at 1000℃

Fig. 1.

4. Improvement performance of electrolyte materials in SOFCs
It is known that Sc2O3 doped ZrO2 with the composition range of X=0.10〜0.12 in (ZrO2)1.00-x(Sc2O3)xshows the highest conductivity of other ZrO2-based solid solutions. However, the problem of these solid
solutions is the phase transition from rhombohedral to cubic. In this study, the oxide ion conductivity of(ZrO2)1.00-x(Sc2O3)x-y(Ga2O3)y(x=0.10〜0.12,Y=0.00〜0.11) were measured.

0logσ(Scm-1)-1

x=0.00x=0.03

0.01

0.04

0.02

0.05

-2

0.06
0.07

-3
-4
-5
-6

Fig. 2

0.8

1

1.2
1.4
-1
1000(1/T) (K )1.6

Arrhenius plots of the electrical conductivity for (ZrO2)0.89(Sc2O3)0.11-x(Ga2O3)x5. Conclusions
In this study, materials of fuel electrode and electrolyte were examined in life evaluation. and highperformance materials of electrolyte was examined. The result of this study is expected to be useful on
development of SOFCs.
[1] M. Hattori, Y. Takeda, S. Ohara, J.-H. Lee, K. Mukai, T. Fukui, Y. Sakaki and A. Nakanishi, Change in
Conductivity of Yttria Stabilized Zirconia, Journal of the Japan Society of Powder and Powder Metallurgy, 50,
297 (2003)[2] M. Hattori, Y. Takeda, Y. Sakaki, A. Nakanishi, S. Ohara, K. Mukai, J.-H. Lee and T. Fukui, Effect of aging
on conductivity of yttria stabilized zirconia, Journal of Power Sources, 126, 23 (2004)[3] M. Hattori, Y. Takeda, J.-H. Lee, S. Ohara, K. Mukai, T. Fukui, S. Takahashi, Y. Sakaki and A. Nakanishi,
Annealing effect of electrical conductivity in the Y2O3-ZrO2 system, Journal of Power Sources, in Press

Abstracts of Doctor’s Thesises

89

Degradation of Organohalogen Compounds by Using Zero Valent
Metals in a Continuous Flow System

Ahmed H. A. Dabwan*
Key words: Degradation, Continuous flow system, Trihalomethanes, Zero valent metals, Bimetals,
Ag/Zn bimetal, Passive layer.

1. Introduction
Contamination of underground water is dominated by halogenated organic compounds (HOCs) that
represent serious environmental threat due to their toxicity and resistance to natural biodegradation. Significant
efforts have been made to develop effective means of eliminating these highly stable compounds from theenvironment. However in each technique there are limitations and disadvantages.
Treatment of halogenated hydrocarbons by active metals looks promising technique. So far, two means ofapplying this process have been demonstrated in the field. One involves placing a permeable zone of granular
metal across the path of a contaminant plume. Remediation is achieved as the plume flows through the reactive
barrier. The other approach involves circulating waste streams or water from pump-and-treat systems throughabove-ground reactors packed with a mixture of active metal and other materials.
The purpose of this study is to develop a continuous flow system for the degradation of trihalomethanes(THMs) by using zero valent metals. Pure Zn, Ni, and bimetallic Ag/Zn were used to evaluate their capability indegradation. THMs represent the most common disinfection by-product besides their application in many areas.
Degradation was carried out under mild conditions in order to reduce the cost and to save energy.

2. Results and discussions
At room temperature however, previous literatures showed that in the Zn/HOCs/H2O mixture, the influence ofoxide film forms immediately in the metal surface is the main obstacle to proceed the reaction even with high amountof Zn0 powder. In order to overcome this problem, we assumed that working under mild temperature (25-50oC)
would lead to destabilization of the passive layer. Under the experimental conditions complete degradation wasachieved for all THMs. Even though complete degradation and high yield efficiency were obtained for both
bromoform (BR), and chlorodibromomethane (CDBM), it was noticeable that chloroform (CH) andbromodichloromethane (BDCM) were found to behave different than BR, and CDBM due to the formation ofCH2Cl2 as intermediate by-products. CH2Cl2 is well known persistent compound. The principal products
obtained in the continuous flow system when Zn powder was used as an active metal were Cl-, Br-, CH4, C2H4,
and C2H6. Ni powder was used to check its efficiency in the degradation of DBCM, the yield of bromide and__________________________________________________________________________________________* Division of Material Science (Department of Chemistry for Materials)

90

Abstracts of Doctor’s Thesises

chloride ions were relatively low even at high temperature (80oC). In another work degradation of THMs
mixture was investigated by using bimetallic Ag/Zn in a batch system in order to obtain more information about
thereactionkinetics

for

each

THM.

In

this

experiment,

degradation

rate

follow

theorder

BR>CDBM>BDCM>CH, and the THMs were readily degraded by bimetallic Ag/Zn system. Furthermore, theeffect of bimetallic Ag/Zn powder on degradation of THMs mixture in a continuous flow system was also
investigated including acid, neutral, and base medium. Precipitation of 3.3% of Ag on the surface of Zn powder
caused complete degradation even at room temperature. It seems that rapid oxidation of Zn was prevented due tothe presence of Ag on the surface which presumably reduces the activation energy needed to proceed the reaction,and due to the large potential created by coupling active metals as well. The main products were Cl-, Br-, CH4,
C2H4, and C2H6.
Multi-step reduction sequence seems to be reasonable to interpret the mechanism involved in the batch
system. Data shows that the disappearance of the primary substrate (THMs) proceeds by kinetics that are
first-order. In the reactor the molecule is consumed continually in the axial direction.CHX3 molecule undergoes
hydrogenolysis to give CH2X2. Once CH2X2 is formed it undergoes further hydrogenolysis to form CH3X,
eventual product of this process is CH4. The other possible route is the formation of radicals and carbenes that
leads to the formation of CH4, C2H4, and C2H6. It is well known that Zn serves as the best metal for carbeniod.
This idea was supported by the GC-FID data where CH4, C2H4, and C2H6 were detected.

3. Conclusion
This system could be generalized to treat not only THMs, but also other halogenated hydrocarbons. The
toxicity in these compounds is essentially attributed to the existence of halogen atoms. Detoxification driving
force is based on the dissolution of metals flowed by coupled hydrogenation of the carbon-halogen bond whichis common in all halogenated hydrocarbons.

Author’s publications
1.

T. Suzuki, A. H. A. Dabwan, A. Yasue, S. Kaneco, and K. Ohta, Degradation of carbon tetrachloride in a continuous
flow system using nickel powder, ITE Lett. Batt. New Technol. Med., 1 (4), 617-620 (2000).

2.

A. H. A. Dabwan, T. Suzuki, S. Kaneco, H. Katumata, and K. Ohta, Continuous Dechlorination of chloroform ofchloroform in a flow system using powder under mild conditions, ITE Lett. Batt. New Technol. Med., 3 (5), 585-588(2002).

3.

A. H. A. Dabwan, T. Suzuki, S. Kaneco, H. Katumata, and K. Ohta, Degradation of CHBrCl2 in a continuous flow
system using metal powder under mild conditions, ITE Lett. Batt. New Technol. Med., 4 (4), 461-464 (2003).

4.

A. H. A. Dabwan, T. Suzuki, S. Kaneco, H. Katumata, and K. Ohta, Continuous degradation of chlorodibromomethane
in a flow system using zinc powder under mild conditions, Photo/Electrochem. Photobiol. Environ. Energy Fuel,
163-171 (2003).

5.

S. Kaneco, H. Watanabe, A. H. A. Dabwan, H. Katumata, T. Suzuki, and K. Ohta, Electrochemical decomposition of
bromoform under mild conditions, ITE Lett. Batt. New Technol. Med., 3 (2), 201-204 (2002).

6.

A. H. A. Dabwan, T. Suzuki, S. Kaneco, H. Katumata, and K. Ohta, Continuous debromination of bromoform in a flow
system using zinc powder under mild conditions, Intern. J. Environ. Studies, submitted.

7.

A. H. A. Dabwan, T. Suzuki, S. Kaneco, H. Katumata, and K. Ohta, Column degradation of trihalomethanes using
bimetallicAg/Zn under mild conditions, Applied Cat. B: Environ., submitted.

Abstracts of Doctor’s Thesises

91

Electrothermal atomic absorption spectrometric determination of traceelements in environmental samples with slurry sampling andpreconcentration techniques
Md. Nurul Amin†
Key words: Electrothermal atomic absorption spectrometry, Metal tube atomizer, Slurry sampling,
preconcentration on tantalum wire

1. Introduction
Environmental analytical chemistry is an important area in environmental chemistry to evaluate
the possible health risk and control of environmental exposure of the general population to toxic chemicals.
From the viewpoint of environmental risk, environmental samples such as foods, river waters and medicines
should be regularly monitored in order to reduce the risks of health hazard. Therefore, it is necessary todevelop a rapid, sensitive, simple and low cost method for the determination of trace and toxic element at
low levels in the environmental samples. Various atomic spectrometric methods form an essential part of themodern instrumental methods of analysis. Electrothermal atomic absorption spectrometry (ET-AAS) with ametal tube atomizer is shown to provide better sensitivity for most metal elements, and better
reproducibility at relatively low power and low cost. In the present study, ET-AAS determination of traceelements in environmental samples was developed in combination with slurry sampling and tantalum wirepreconcentration techniques.
2. Experimental
A molybdenum tube atomizer (20 mm x 1.8 mm i.d., wall thickness 0.05 mm), made from purity
molybdenum sheet (99.95 % purity, Rembar), was used for slurry sampling ET-AAS for manganese, copperand cadmium analysis. The samples were injected by means of a glass micropipette through a 0.3 mm
diameter hole at the mid point of the tube. The atomizer was mounted on two supports so that there was no
localized variation in tube temperature. The microtube atomizer was enclosed in a Pyrex chamber (300 mL
volume) which had two silica end-windows to allow transmission of the light beam. The chamber was
flushed with inert gas to protect the atomizer from oxidation by entrained air. Power for heating theatomizer was supplied by a stepdown transformer. Switching was done with a manual double-pole
double-throw switch and timing was done with a stopwatch.
Atomic absorption measurements were performed using a Nippon Jarrell-Ash 0.5 m Ebert-type
monochromator equipped with an R928 photomultiplier (Hamamatsu Photonics Co.), a fast response
amplifier, a storage oscilloscope (Kenwood CS-8010) and a microcomputer (PC 9801 FA, NEC
Corporation). The atomizer was a tungsten tube (20 mm long and 1.5 mm i.d., 0.05 mm thick and 99.95%
purity, Rembar Co.). The electric power for heating the atomizer was supplied by two transformers(Yamabishi volt-slider, S-130-30, Cap 3 kVA). Two pinhole apertures were placed in the front and rear of
the atomizer, in order to collimate the light beam and eliminate the radiation from the atomizer surface.
Tantalum wire for adsorption preconcentration of chromium and antimony were 17 mm long with adiameter of 0.5 mm (99.95% purity, Goodfellow Co.).
† Division of Materials Science (Department of Chemistry for Materials)

92

Abstracts of Doctor’s Thesises

3. Results and discussion
Results obtained for the determination of manganese and copper in the three herbal medicine
samples and cadmium in Bangladeshi vegetable samples by the proposed method were in good agreementwith those measured in the nitric acid digested samples. To validate the precision and accuracy of themethod recovery tests were performed, which shows a recovery in the range of 105 to 108%, 89 to 115%
and 97 to 103% for manganese, copper and cadmium, respectively. The result of the present study showsthat analysis of trace elements in biological samples are shown to be an optimistic by slurry sampling withmolybdenum method using ET-AAS. Applications of this recommended technique can be extended to theroutine analytical task for other kinds of biological and environmental samples provides good analytical
performance with the advantages of simplification of sample pre-treatment, diminishing the turnaround timeand operational work, less risks for sample contamination, minimization of analyte losses caused either by
the pre-treatment operations or by the incomplete release of the analyte from the solid matrix, it prevents theuse of dangerous and corrosive reagents, applicability to both organic and inorganic samples, capability for
micro-heterogeneity measurements, faster analytical capability and lower cost.
A direct preconcentration method for ultra trace concentrations of chromium and antimony in riverwaters adsorption on a tantalum wire followed by electrothermal atomic absorption spectrometry combinedwith a laboratory constructed tungsten tube atomizer has been developed. Preconcentration has frequently
been applied in the determination of ultra trace analytes in complex matrix samples by instrumental analysis.
The best pH for the adsorption of chromium and antimony was 3 and 2, respectively. The optimal
immersing time was 120 s for both. Under the optimal conditions, the detection limit of chromium andantimony by the tantalum wire preconcentration method was 15 pg/mL and 50 pg/mL (3 S/N), respectively.
The relative standard deviation for 5 µg/L of chromium was 9.7% for 10 measurements, while in the case of
antimony was 9.4% for 14 measurements. The relatively large RSD may be attributed to the variation in theposition with respect to the water surface by stirring. The effects of large amounts of concomitants on thepreconcentration of chromium and antimony were evaluated. Even though 103-104 fold excess of matrix
elements existed in water, the chromium and antimony response were not significantly affected by thematrix elements. To validate the precision and accuracy of the method recovery tests were performed, whichshows a recovery of spiked-chromium and antimony in the range of 95.8 to 10% with RSD better than 10%
for >5 measurements and 99.5 to 114% with 12% for >3 replicate analysis, respectively.
4. Conclusion remarks
The technique developed was shown to be a attractive specific features of ET-AAS are excellent
absolute limit of detection, microsampling for slurries, solids and liquids, relatively simple pre-instrumental
treatment, reliable contamination control and coupling with enrichment techniques-down to ng/L limit ofdetection. The proposed method fulfills the requirements of a fast and rugged routine procedure for the
reliable determination of trace and toxic elements, with high accuracy, in a wide variety of environmental
samples. Thus, the recommended method will be useful for reliable measurement as a regular quality
control technique and or as a screening approach in different processes such as industrial and environmental
fields.
Author’s publications[1] M.N. Amin, H. Okada, S.I. Itoh, T. Suzuki, S. Kaneco and K. Ohta, Fresenius J. Anal. Chem., 371,
1130-1133 (2001).
[2] M.N. Amin, S. Kaneco, T. Suzuki, Y. Taniguchi and K. Ohta, Anal. Bioanal. Chem., 373, 205-208(2002).
[3] M.N. Amin, S. Kaneco, T. Suzuki and K. Ohta, Microchem. J., 74, 181-186 (2003).
[4] M.N. Amin, S. Kaneco, K. Nomura, T. Suzuki and K. Ohta, Microchim. Acta, 141, 87-91 (2003).
[5] M.N. Amin, S. Kaneco, T. Suzuki and K. Ohta, Intern. J. Environ. Anal. Chem., 83, 1035-1044 (2003).
[6] M.N. Amin, S. Kaneco, T. Suzuki and K. Ohta, Res. Rep. Fac. Eng. Mie Univ., 28, 9-24 (2003).

Abstracts of Doctor’s Thesises

93

A Study on Application of Fractal Analysis to Solve Surface Problems in Manufacturing and Nanofabrication Processes
Mir Behdad Khamesee(Department of Mechanical Engineering, Division of Materials Science)
Keywords: material testing, measurement, surface nanostructure, nanofractal analysis, nanotechnology, atomic
force microscope, two-dimensional fast Fourier transformation, computer simulation, computer-aided engineering
1. Introduction
In metal forming operations, surface structures of metals and tools are closely related to various surface problems,i.e., forming limit, coating feasibility, galling and other tribological characteristics. Recently, the accuracy andquality of nanotechnology processes have markedly improved, and thus, information related to the detailed geometry of such surface structures on the nanometer scale has become necessary as well as their complexities. Although a number of investigations on material surface phenomena have been carried out, as of yet information on
surface nanostructures has been insufficient. One of the reasons is that, the surface structures involve various classesof randomness and are difficult to characterize quantitatively. In order to analyse these structures, the authors
proposed a fractal approach, and verified its validity against our past researches, where one-dimensional fractal
analyses were employed under a micro/meso scale.
The self-affinity and fractal nature property of these surfaces are investigated. Next, the fractal approach is extended
to the two-dimensional (2D) fractal method, and thus, the two-dimensional fast Fourier transformation (2D-FFT)
analysis is also applied to these surfaces. Moreover, by modeling the 2D power spectrum distribution, a method for
simulating the surface nanostructures of any materials is presented, and also its validity is examined for various
materials with in-plane isotropic and anisotropic surfaces. In addition, based on these results, a CAE system composed of 2D-FFT and inverse FFT (IFFT) is advanced, and its application is presented and discussed regarding thevarious surface problems.
2. Power Spectrum Method
The power spectrum SP and the wavelength λ were obtained by applying one-dimensional FFT analysis to thesurface profile curves, and the following relation was assumed.
SP ∝λβ(1)
The fractal dimension DPS was determined from the slope of the log (SP) vs log (λ) plot, denoted by β, as:
DPS = 2,0 ≦β ＜1
DPS = E + (3-β ) / 2,
1 ≦β ≦3(2)
3 ＜βDPS = 1,
where E is the Euclidean dimension, and E = 1 in this study.
3. Zeroset Method
Intersections of surface irregularities and the basal plane, referred to as zeroset elements here, are generated andtheir shapes are directly observed. Even if surfaces are self-affined and isotropic in-plane, the resultant zeroset
elements become self-similar and reduce their fractal dimensions by one. When the area and the peripheral length ofeach zeroset element are denoted by Az and Lz, respectively, the fractal dimension Dz is obtained from the following
relation.
Az1/2 ∝ Lz1/Dz（3）When the relation between Lz and Az is measured experimentally, the zeroset dimension Dz can be determined by
the following equation from the slope of the log(Lz) vs log(Az) plot, denoted by αZ.
Dz=2αz（4）
4. Nanofractal Dimensions
The relationship between the power spectrum SP and wavelength λ of A1100-O was investigated, where a linear
relationship was found between SP and λ. Moreover the relationship between SP and λ for all the tested materials
was investigated. It was found that relation (1) holds for all materials, showing a fractal nature. The zeroset dimension Dz and the power spectrum dimension DPS have different values. Dz is a direct measure of the complexityof surface irregularities, whereas DPS is different from the physical viewpoint in that it is a measure of wavelength
dependability when the surface is viewed as a spectrum. If the magnifying power increases, Dz decreases, indicatingthat the surface becomes smooth. On the other hand, DPS slowly increases with increasing magnifying power, incontrast to Dz. This shows that the influence of the short-wavelength ingredient of a cross-sectional curve is re-94

Abstracts of Doctor’s Thesises

flected strongly, when the magnifying power increases. According to the self-affinity and two fractal analyses, all
the tested surfaces were found to be self-affined fractals in the range down to at least SR=500nm, corresponding to a
resolution of 1nm.
5. Two-Dimensional FFT Analysis on Material Surface
Employing one method, 2D-FFT was carried out on 2D-AFM images of in-plane anisotropic aluminum sheets(A1100-O), and their power spectra were examined. The spectrum obtained by FFT shows the strength of the power
spectrum SP in each (kx,ky). The values of kx and ky are wave numbers of unit of length in the x and y directions,where x corresponds to the rolling direction and y is the direction perpendicular to it. The curves were examinedusing the constant values of ky, and the result was the same. Accordingly, it was concluded that the power spectrum
image is symmetrical through two midplanes, and thus, the image was divided into four portions (A, B, C, D).
Therefore, if the portion of A is modeled, the whole power spectrum image can be determined.
6. Examination on surface smoothing in high-precision metal forming
One of the applications of the present CAE system is to confirm the possibility of its utilization to the nanotechnology process in metal forming. After pressing, the surface roughness Rz was measured for each compression ratio
eC in the cases of 0˚ and 90˚ directions. The Rz decreases with increasing compression ratio, indicating that theplastic deformation causes the large-wavelength components to grow, which reduces the surface complexity. The
roughness of the tool surface was 50nm, and the minimum Rz in the pressed surfaces was 140nm at a compression
ratio of 65%. These simulation results were in good agreement with the experimental results.α which expresses
roughness characterizations, decreases with increasing compression ratio, and this tendency is matched with avariation of Rz. In addition, the surface complexity which decreases with increasing compression ratio is matchedwith a change in β. Thus the quality of the deformed surface structure can be judged by these parameters. Therefore,
the proposed system is regarded as useful for understanding the surface nanostructures of products manufactured
through high-precision press forming. Finally, while the 3D surface information constitutes 512×512 elements, it
can be reproduced through only three parameters α, β and γ using the advanced CAE system. Accordingly, thesystem is also regarded as applicable to so-called information compression.
7. Concluding Remarks
The results obtained in the present research are summarized as follows:
1) From the results of the one-dimensional fractal analysis, it was found that the surfaces of all used materials are
self-affined fractals at a resolution of 1nm.
2) The results obtained for two-dimensional FFT of AFM images showed that the meridian cross-sectional curve
had a fractal nature.
3) The spectrum distribution could be modeled adequately by introducing its symmetry in the wave-number space
and an anisotropic parameter.
4) By using only three parameters a simulator was successfully developed, which can carry out the creation of
three-dimensional surface features at the same level of complexity as that of the actual surface.
5) A CAE system composed of 2D-FFT and 2D-IFFT was constructed for quantitative estimation of the surface
structures and its various applications were shown to be valid.
6) The mass data of surfaces could be compressed into only three parameters using this system. This compressed
information includes all surface waviness, complexity, irregularity, roughness and anisotropic properties.
Author’s Publications
1.

2.

3.

4.

5.

6.

M.B. Khamesee, Y. Kurosaki, M. Matsui and K. Murai, "Nanofractal Analysis of Material Surfaces Using Atomic
Force Microscopy", Materials Transactions, Journal of the Japan Society for Technology of Plasticity, Vol. 45, No. 2,
February 2004, pp. 469-478.
M.B. Khamesee, M. Matsui, K. Murai, T. Ishihara and Y. Kurosaki, "Quantitative Estimation of Fracture Surface forMild Steel Using Fractal Analysis", Proceedings of the 6th International Symposium on Microstructures and Mechanical Properties of New Engineering Materials (IMMM), Wuhan, China, October 2003, pp. 147-152.
M. Matsui, Y. Kurosaki, M.B. Khamesee and K. Murai, "Prediction of Free Surface Profile of Sheet-Formed Products Using a Fractal Approach", Journal of the Japan Society for Technology of Plasticity (JSTP), Vol. 43, No. 498,
July 2002, pp. 644-648.
M.B. Khamesee, Y. Kurosaki, M. Matsui and K. Murai, "Fractal Approach for Prediction of Surface Profiles of
Sheet-Formed Products", Proceedings of the 4th International Conference on Mechanics and Materials in Design(MMD-4), Nagoya, Japan, June 2002, pp. 175-176.
M. Matsui, Y. Kurosaki, M.B. Khamesee and K. Murai, "A Study on Predicting the Surface of Pressed-Products
Using Fractal Analysis", Proceedings of the 51st Conference of the Japan Society for Technology of Plasticity (JSTP),
Seki, Japan, November 2000, pp. 455-456 (in Japanese).
Y. Kurosaki, M. Matsui, K. Murai, T. Ishihara, M.B. Khamesee and Y. Tamaki, "A Study on the Quantitative Estimation of the Fracture Surfaces for Analysis of Accidents", Proceedings of the 51st Conference of the Japan Society
for Technology of Plasticity (JSTP), Seki, Japan, November 2000, pp. 333-334 (in Japanese).
94

Abstracts of Doctor’s Thesises

95

Degradation of endocrine disrupting chemicals in environmental
samples by microorganisms and application to their easy analysis
Aleya Begum†
Keywords: Phthalic acid esters, Saccharomyces cerevisiae, Bacillus subtilis, metabolites, degradation
pathway, preconcentration, immobilized.

1. Introduction
Phthalic acid esters (PAEs), which are widely used as plasticizers and are produced in large
quantities, have received extensive attention in recent years due to their widespread use and ubiquity
in the environment. Degradation based on the activity of enzymes and microorganisms, such asbacteria, fungi, algae and protozoa, are of growing importance for degradation and sorption ofchemical compounds, due to their simplicity, rapidity, cost-effectiveness and reproducibility.
Microorganisms immobilized on several inorganic adsorbents have been used for preconcentrationand speciation of trace metal ion.
2. Experimental
PAEs were dissolved in Ammonium di-hydrogen phosphate (ADP) solution (cultivation
medium). Yeasts were grown in the cultivation medium at 40 °C for 15-60 min. The cultivation was
performed at 20-50 °C for 12-72h. After the cultivation, the PAEs solution with yeasts were filteredthrough a membrane filter (0.5 µm). The filtrate used for PAEs analysis.The PAEs concentrations of
all samples were determined by high performance liquid chromatography (JASCO Co., Tokyo, Japan)
with a UV detector (254 nm). The intermediate products were analyzed by gas chromatography-mass
spectrometry (GC/MS) using a Model QP5000 (Shimadzu Co., Kyoto, Japan).
For adsorption Saccharomyces cerevisiae was grown in 20 mL of sample solution containing
ADP at 40 °C for the growth of yeast. The cultivation was performed at 20–50. After cultivation, thesolutions were filtered and the filtrate used for PAEs analysis.
For the immobilization of yeast cells, dry yeast was mixed with silica gel at 1:5 ratio. The
mixture was wetted and mixed with water, then the paste was heated in an oven at 105°C for 3 h to
dry the mixture. A glass column plugged with a small portion of a glass wool was filled with S.
cerevisiae immobilized on silica gel. The PAEs solutions were separately passed through the column
at a flow rate of 3 mL min–1. Then, the retained PAEs were eluted from S. cerevisiae immobilized on
silica gel with 2.5–7.5 mL ethanol. The analytes in the eluates obtained were determined by HPLC.
For the preconcentration of trace silver, yeast with (NH4)2HPO4, was added to a river water andcultivated at 25 0C for 2 h. The cultivated mixture was filtered with 3.0 µm membrane filter and thecollected yeast on the filter washed with flush ultra-pure water and 0.1 M nitric acid. Atomic
absorption measurements were made with a Nippon Jarrell-Ash AA/AE spectrophotometer (AA-855)
equipped with an auto-background corrector and a graphite furnace atomizer (Tube type 228-3110).

† Division of Materials Science (Department of Chemistry for Materials)

96

Abstracts of Doctor’s Thesises

3. Results and discussion
A degradation process of endocrine disrupting chemicals such as phthalic acid esters (PAEs)
by microorganism has been developed. The biodegradation of phthalic acid esters namely, Diethyl
phthalate (DEP), Dibutyl phthalate (DBP) and Butyl benzyl phthalate (BBP), in aqueous solutions
with baker’s yeast S. cerevisiae and DBP with Bacillus subtilis (formerly Bacillus natto) were
investigated. Ammonium dihydrogen phosphate(ADP) was used as a culture medium. Under optimum
conditions the degradation rate of DEP, DBP, and BBP were 62%, 96% and 90% respectively by S.
cerevisiae The kinetics study demonstrated that the biodegradation of DEP, DBP and BBP by S.
cerevisiae conformed to the first-order reaction. In the case of B. subtilis, under the optimal conditions,the degradation percentage of DBP was 72% after 24 h cultivation.
The metabolites of DEP appeared to be ethyl methyl phthalate (EMP), dimethyl phthalate(DMP) and phthalic acid (PA), whereas dipropyl phthalate (DPP), diethyl phthalate (DEP), monobutyl
phthalate (MBP) and PA were identified as metabolites of DBP, and MBP, DEP and PA were appeared
as metabolites of BBP. In the case of Bacillus subtilis, the metabolites of DBP were identified as DPP,
MBP and PA.
The adsorption behavior of DEP and DBP from aqueous solution to baker’s yeast wasquantitatively characterized. The experimental results showed that the adsorption efficiency of DBP
was much higher than that of DEP. The heat of adsorption of DBP was 373 KJ mol-1, indicating thatthe adsorption behavior seemed to be chemical adsorption.
The PAEs were preconcentrated on Saccharomyces cerevisiae immobilized on silica gel
Several parameters on the recovery of the analytes were investigated. Recoveries of BBP, DBP and
DCHP were 100±2, 98±2 and 98±3%, respectively, at 95 % confidence level under optimum
conditions. The capacity of the adsorbent was found to be 1 .4 mg g-1 for BBP and DBP, and 3.6 mg
g-1 for DCHP. The proposed method was successfully applied to the determination of PAEs in riverwater with high precision and accuracy.
A new preconcentration method with baker’s yeast was evaluated for the determination of
trace silver in river waters by graphite furnace atomic absorption spectrometry (GFAAS). Under
optimal conditions, silver in aqueous sample was concentrated to 6.9-fold by yeast. The recovery of
spiked silver was in the range of 89 to 110%. By the preconcentration, it was found that ultra trace
silver in river waters could be determined without interferences of matrix elements, after only thecultivation and with no chemical treatment.
4. Conclusion
The proposed biodegradation and biosorption method by microorganisms offer great
promise for the accelerated, very simple, inexpensive, and safe removal and cleanup of organic andinorganic pollutants from the environment. Thus, the yeasts will be a suitable candidate for endocrine
disrupting chemicals degrade and removal from environmental contamination site.
Author’s publications[1] K. Ohta, K. Saruma, S. Kaneco, T. Suzuki, S. Itoh and A. Begum, Annali. di. Chim., 92, 587-594(2002).
[2] A. Begum, H. Katsumata, S. Kaneco, T. Suzuki and K. Ohta, Bull. Environ. Contam. Toxicol,, 70,
255-261 (2003).
[3] A. Begum, H. Katsumata, N. Sakuma, S. Kaneco, T. Suzuki and K. Ohta, Photo/Electrochem.
Photobiol. Environ. Energy Fuel, 155-162 (2003).
[4] A. Begum, H. Katsumata, S. Kaneco, T. Suzuki and K. Ohta, Fresenius Environ. Bull., 12,
1309-1314 (2003).
[5] H. Katsumata, A. Begum, S. Kaneco, T. Suzuki and K. Ohta, Anal. Chim. Acta., 502, 167-172(2004).
[6] A. Begum, H. Katsumata, S. Kaneco, T. Suzuki and K. Ohta, Environ. Eng. Sci., submitted.
[7] A. Begum, H. Katsumata, S. Kaneco, T. Suzuki and K. Ohta, J. Environ. Management, submitted.

Abstracts of Doctor’s Thesise

97

Mechanistic Study for Efficient Photo-initiator Generation
Koichi Kawamura †Keywords: Polymerization, Photoinitiation, Radical, Sensitization, Merocyanine, Electron transfer

1. Introduction
Many attempts have been made to develop efficient photoinitiating polymerization systems that can be used
upon visible light excitation since such systems are expected to have wide applications in typical practical fields,such as high-speed photopolymers in computer-to-plate laser imaging and 3D polymerization systems. In such
systems, the photopolymerization occurs by electron transfer from a photo-excited donor (dye) to an acceptor(initiating part) molecule. It is generally accepted that the rate of the electron transfer Ket depends not only on
the free energy change but also on the distance between donor and acceptor. Dye-linked photoinitiators, inwhich a radical generating part is brought close to a photosensitizing dye-chromophore by a covalent bond, havebeen shown to be very useful as free-radical sources. However, the details of photo-processes of those systems
are not clear. In order to investigate these issues, we have prepared several dye-linked photoinitiating systems
and investigated their photochemical behaviors. For this purpose, the following new photoinitiators (Figure 1)
were prepared, in which a merocyanine chromophore and a bis(trichloromethyl)-1,3,5-triazine chromophore
were linked by a different number of methylene chains (MT1, MT3) and at different positions (MT1, MT2).
2. Results and Discussion
The absorption spectra of linked compounds (MT1, MT2 and MT3) were almost identical with that of anequimolar mixture of each component merocyanine and triazine (M+T). This indicates that there is noappreciable interaction between these two chromophores in the ground state. The spectral change observed bysteady-light irradiation of MT1 in deaerated toluene are shown in Figure 2. When a solution of MT1 wasirradiated with a light of 430 nm wavelength, where only
the dye was excited, the band at 430 nm that is
CCl3
O
O
N
characteristic of the dye disappeared and a new band
CH
O
C
CH
N
2
2
S
showing its maximum at 380nm appeared, with anNN
CCl3
isosbestic point at 390 nm. Similar spectral changes wereN
S
S
observed under irradiation of other MT systems.
MT1
n‑C8H17O
In marked contrast, similar irradiation of an equimolar
S
C2H5
N
mixture of the dye (M) and the triazine (T) showed
CCl3
NS
essentially no change at least in the time range whereSN
MT2
appreciable decay was noted for the linked system. The
N
CH2CH2O CNOobservations can be interpreted as indicating that MT
CCl3
CCl3
O
systems undergo intramolecular electron transferO
N
S
reaction upon photoexcitation much faster than M+T
N CH2CH2OCH2CH2O C
NNsystem under these conditions.
N
S
CCl3
S
The relative efficiency of merocyanine-linked triazines
MT3
n‑C8H17
as an initiator in photoinitiating systems of acrylatesO
CCl3
monomers was evaluated by monitoring the
C2H5
O
N
S
N
disappearance of the acrylic double bond in the IR
N
CH3 OCN
N
S
absorption (Figure 3). Three merocyanine-linked
S
CCl3
T
n‑C8H17 M
photoinitiators, MT1, MT2, and MT3 and physicalmixtures of merocyanine/triazine were used. The results clearly showed that the rate is markedly enhanced when
the linked photoinitiators were used, as opposed to the
Figure 1. Dye-linked initiators (MT1, MT2 and MT3)
unlinked photoinitiator combinations. Among the liked
and reference compounds (M, T).
initiators, MT3 is much less effective for photoinitiating
polymerization than MT1 and MT2, and MT2 shows†

Fuji Photo Film Co., Ltd.,Abstracts of Doctor’s Thesises

larger initiation rate than MT1, although they havethe same number of methylene chain.
The major difference between MT1 and MT2 isthe position to which the triazine is connected tothe dye. The reason for the enhanced interaction in
MT2 may be attributable to the more effective
orbital interaction between the triazine moiety andthe photoexcited sensitizing moiety in MT2 system,compared to that in MT1 system. We evaluated thedonor-acceptor distance of the linked compoundfrom the most stable conformer which was
obtained by searching low-energy conformations
by CONFLEX method in CaChe® calculating
system and the result indicates the more effective
interaction in MT2 than in MT1.

1

0 sec
0.8

Ab sorb ance

98

5 sec
10 sec15 sec30 sec0.6

0.4

60 sec

0.2

0

300

350
4 00
W avelength / nm

4 50

5 00

Figure 2. Change of absorption spectra of MT1 upon
irradiation at 430nm in toluene.

3. Conclusions

Author’s publications

40
MT2
30
Conversion (%)

The photochemical and photophysical processes
were examined in a solution and in a photopolymer
matrix used in practical photopolymerization
systems. The initial reaction step between thephotoexcited merocyanine and the triazine wasconcluded to be electron transfer based on the
products
analysisandthermodynamic
considerations. In the dye-linked photoinitiating
systems, the number of methylene unit between thelight-absorbing moiety and the radical-generating
moiety is demonstrated to be an important factor tocontrol the photochemical reactivity. The linking
position is also found to show a slight but distinct
effect on the efficiency. Those findings give a clue
to develop new dye-linked photoinitiators which
are highly sensitive to a visible light.

MT1
MT3

20

M+T
10

0
0

200

400
600
Irradiation time / sec

800

Figure 3. Conversion (%) of acrylate double bonds as afunction of time for polymerization of acrylates containing
photoinitiators on irradiation (λ= 430 nm, Intensity = 34
mW/cm2). Photoinitiating system (24mmole/ dm3) ; M+T(●), MT1 (○), MT2 (∆ ), and MT3 (□).

[1] Koichi Kawamura, Yoshimasa Aotani and Hideo Tomioka, “Photoinduced Intramolecular Electron Transfer between
Carbazole and Bis(trichloromethyl)- s-triazine Generating Radicals”, Journal of Physical Chemistry, B, (2003), 107,
4579–4586.
[2] Koichi Kawamura, “Novel and Efficient Dye-Linked Radical Generators for Visible Light Photoinitiating
Polymerization”, Journal of Photochemistry and Photobiology A: Chemistry, (2004) 162, 329–338.
[3] Koichi Kawamura and Kunimasa Kato, “Synthesis and Evaluation as a Visible-Light Polymerization Photoinitiator of a
New Dye-Linked Bis(trichloromethyl)-1,3,5-triazine”, Polymers for Advanced Technologies, (2004) in press.
[4] Koichi Kawamura, “Merocyanine-dye-sensitized Photoinitiator Generating a Free-radical via an IntramolecularElectron-transfer Process”, Chemistry Letters, (2003) 32, 1068-1069.
[5] Koichi Kawamura, “Mechanistic Studies of the Photo-decomposition of Substituted Bis(trichloromethyl)- 1,3,5-triazine
Sensitized by Merocyanine Dye”, Chemistry Letters (2003) 32, 832–833.
[6] Koichi Kawamura, Kunihiko Kodama, Katsuyuki Hirai and Hideo Tomioka, “Laser Flash Photolysis Study of
Dialkylphenacyl Sulfonium Salts”, Chemistry Letters, (2004) 33, 148–149.
[7] Koichi Kawamura and Fumihiko Sasaki,
Photoinduced Generation of Sulfonic acid from N-SulfonyArysulfonamide ，Journal of Photopolymer Science and Technology, （2001） 14, 265–271.
[8] Koichi Kawamura, Intramolecular Electron Transfer in Carbazole Linked Radical Generators ，RadTec Asia ’03,
Conference Proceedings， (2003) 185-188.
[9] Koichi Kawamura ， Dye-Linked Photoinitiators; Synthesis and their Characterization ， RadTec Asia ’97,
Conference Proceedings，(1997) 271-274.
[10] Koichi Kawamura and Hirotaka Mastumoto, Dye-Linked Photoinitiators ，Proceedings of 45th Annua1 Conferenceof the Society for Imaging Science and Techno1ogy VA，Springfield，(1992) 337-340.

99

Abstracts of Doctor’s Thesise

A Study on Distortional Bucklingof Thin-walled Light Gauge Steel Members
Koji Hanya*
Keywords: c o l d - f o r m e d s t e e l m e m b e r s , f l e x u r a l s t r e n g t h , C o m p r e s s i o n s t r e n g t h ,fire resistance tests, strength evaluation methods
Table 1 Distortional Buckling of Members
(a)
(b)
(c)

Introduction
Cold-formed thin-walled steel memberswith thicknesses of around 1mm are relatively
new structural members in Japan. It is becausesuch a thin steel member had not been longallowed to use as a structural member under theJapanese Building Standard Law. This situation
has been changed in recent years through thedevelopment of steel-framed houses. Although
the use of such a thin steel member is currently
possible, there are still some design issues to beclarified for realizing the broader applications,mainly related to its complex buckling behavior.
The complex buckling is called distortional
buckling (Table 1(b), Table 2 (c) ). To study the
behavior of this distortional buckling in detail, it
was done four kind of investigations in thisresearch.

Local
buckling

Distortional
buckling

Flexuralbuckling(d)Torsional‑flexura
buckling

Table 2 Distortional Buckling of Plates(a)(b)
SectionSectionLocalbucklingof plate

Discussions(c)
SectionLocal buckling
Distortiona
lbucklingof plate with stiffenersof plate with stiffeners

1) In the case of flexural members, the distortional buckling is often seen in the floor and roof
panels in steel-framed houses. Negative bending tests were therefore conducted for panels
consisting of two lipped-channels and structural plywood fastened together with screws (Fig. 1).
Twelve bending tests provided detailed behavioral information on distortional buckling and thepossible strength evaluation methods for improving the design of thin-walled steel members.
2) In the case of compression members, the panels mainly consist of witch both side oflipped-channels are attached to structural plywood. In this case, the distortional buckling aren’tside as the floor and roof panels. Therefore it was conducted first that twenty compression testsof lipped-channels without structural plywood (Fig. 2), and then done the fourteen panels withstructural plywood.
Screws

Structura
lplywood

En d Plate

P

90

Se

tw

86

y

H

Lipped‑channel

x

230

450
910

P/2

230

Section80

80

Section
Lb

P/2

P/2
Lipped‑channel

P/2

D
H

W
910

SectionFig.1 Specimen of Bending Tests*Nippon Steel Corporation

910

Fig.2 Specimen of Compression Tests

Fig.3 Hat-shaped Specimen

100

Abstracts of Doctor’s Thesise3) Due to design thin-walled steel members effectively, it is necessary to consider theintermediate stiffeners. It was conducted that eighteen bending tests of hat-shaped sections (Fig.
3), to clarify the relationship buckling behavior and variety of the stiffeners, that is, width, depth,
shape and numbers of the stiffeners.
4) The application of the thin-walled steel members to the houses requiring fire resistance has
been limited, due mainly to a lack of information on mechanical properties and buckling
behavior of such a thin steel member under elevated temperatures. Therefore, material tensile
tests and compression column tests were conducted to clarify the characteristics and to examine
if information under normal temperature can be applicable. The tests covered a thickness from
0.5mm to 1.6mm and a temperature up to 600ºC.
Conclusionsi) Two types of distortional bucking modes were observed in the tests, the lip-flange distortional
buckling and flange-lip distortional buckling with the lipped-channels.
ii) It was able to evaluate the buckling modes with lipped-channels by using an eigenvalue
analysis of elastic buckling.
iii) Using the von Karman’s formula, it was able to convert the elastic distortional bucklingstrength into the allowable strength or the effective width, in which the yield point and the post
buckling behavior were considered.
iv) It was tried to clarify the relation between the elastic distortional buckling strength and thedimensions of the lipped-channels. From the experimental and analytical investigations, that
relationship was given as the simple formulae consisting of height of the web H, width of theflange W, depth of the lip D, thickness of the material t and the buckling length L b of thelipped-channels.
v) Buckling design formulae for normal temperature may be applied to estimate the column
strength of thin-walled steel members under high temperatures up to 600ºC.
Author’s publications[1] Koji Hanya, Ryoichi Kanno, Shosuke Morino : Distortional Buckling of Thin-walled Lipped
Channel Partially Restrained with Attached Theathing Subjected to Bending, Journal of
Structural and Construction Engineering, No. 567, pp.157-164, 2003.5 (in Japanese)[2] Shosuke Morino, Jun Kawaguchi, Yasumori Mizuno, Koji Hanya : Distortional Buckling ofLight-Gauge Lipped Channel Short Columns, International Journal of Steel Structure Vol. 3, No.
3, pp.203-217, 2003.9[3] Koji Hanya, Rhoichi Kanno : Study on Composite Panels Consisting of Cold-formed Steel
Channels and Plywood with Self-drilling Screws, ASCE Proceedings of Structural Congress
XV Vol.1, pp.428-432, 1997.4[4] Koji Hanya, Ryoichi Kanno, Shosuke Morino,Mamoru Kohno : Material Properties andBuckling Behavior of Cold-formed Thin-walled Steel Members under Flevated Temperatures due
to Fire, Journal of Structurak and Construction Engineering No. 582, 2004.8 (in Japanese)

Fig.6a Local
Buckling
Fig.4a Lip-flange
Distortiona l Buckling
Fig.6b Distortional
Buckling

Fig.4b Flange-web
Distortiona l Buckling

Fig.6c Distortional
Buckling with Local
Buckling
Fig.5 Distortional BucklingAbstracts of Doctor’s Thesises

101

Experimental Studies on Atmospheric Boundary Layer on Complex Terrain
and Mutual Interference of Wind Turbines in Large Scale Wind Farm
Takeshi Yokota†(Department of Mechanical Engineering)
Keywords: wind energy assessment, atmospheric boundary layer, complex terrain, Doppler Sodar,
mutual interference, wind tunnel tests
Abstract
Recently, Wind energy penetration is soaring all over the world especially in the European countries, due to the
Global Warming Concerns. Also in Japan, several 10MW-Class Wind Farms have appeared in a recent few years, as theresults of the new energy promotion programs, which includes the wind energy, by the governmental bodies and theutility companies.
In Japan, the wind resource assessment, for developing the large scale wind farm with several tens of the windturbines, implies at least two major problems which must be overcome, due to the complexity of topography. The firstone is the understanding of the wind profile as a result of the flow distortion due to the complex terrain; the second one isto know how the terrain complexity affects the mutual interference of Wind turbines.
This dissertation settles the all outcomes through the following studies which give the ideas for making solutions of
the two major problems as mentioned above. It deserves to be referred both for practical use and academic knowledge.
Chapter 1; Introduction
In this chapter, the state-of-the-art technologies, which contribute the world wide promotion of the wind power
generation, are summarized first. Then, after reviewing the investigation history of the wind resource assessment and themutual interference of Wind Turbines from the literature, these problems in the complex terrain and the objects of thisstudy are pointed out.
Chapter 2; Experimental apparatus and the principle of Doppler Sodar observation.
In order to know the vertical wind profiles in the various topography, this study were carried out by observing it directlyfrom the ground level through 1,000m height with the use of Doppler Sodar. For observing the wind profile, themonostatic method, which is transmitting the tone burst to three directions in the atmosphere by time sharing from one
point on a ground, is applied. The principle of acoustic sounding is on the detection of the backscattered signal fromrefractive index discontinuities or disturbances in the atmosphere. This system is composed of one vertical antenna andtwo tilted antennas with elevation angle of 70 degree. The tilted antennas are set in the direction of 90 degree each other.
The vertical and tilted beams were cycled through three beams once every 10 seconds, that is, one complete data set is
obtained once every 30 seconds. Analyzing a set of data, three components of wind velocity and the standard deviationof each component are calculated. The cup anemometers and wind vanes are also used for observing the wind profile in
the lower height (10m〜20m).
Chapter 3; Assessment of Local Wind Energy by Sodar TechniqueThis chapter describes the measurement of the atmospheric boundary layer for siting the wind farms. The measurements
were carried out at the sea coast at Konbumori cape in Hokkaido Island. The vertical wind speed distributions up to
1000 meters high were measured by means of the Doppler SODAR. The measured wind speed distributions indicate theeffects of the geometrical shape and the roughness of the ground depending on the wind direction. Measured wind

† Electric Power Development Co., Ltd.

102

Abstracts of Doctor’s Thesises

profile did not agree with power law plots at higher layer. The Weibull distribution also depends on the wind direction
and height.
Chapter 4; Measurement of Atmospheric Boundary Layer for Siting Wind Farms.
This chapter describes the measurement of the atmospheric boundary layer for siting the wind farms. The measurements
were carried out at the gentle hill at Tomamae town in Hokkaido Island. The vertical velocity distributions up to 1000
meters high were measured by means of the Doppler Sodar. The measured velocity distributions indicate the effects ofthe geometrical shape and the roughness of the ground depending on the wind direction. The stream wise velocity along
the flat ground is decreasing with increasing the distance from sea coastline.
Chapter 5; Wind Power Prediction on Complex Terrain in Japan.
In order to accurate estimation of the future wind energy capture, the vertical and horizontal wind velocity distributions
on the complex terrain are measured with the use of Doppler SODAR and meteorological anemometers. The windvelocity reduction due to ground skin friction or ground shape is also shown. Compared to estimation by power law of
the wind profile, the estimated power due to the logarithmic law of the wind profile gives better agreement with theactual generation power. The factor of the differences between estimation and measurement is caused by the fluctuationof the wind speed.
Chapter 6; The Wind Assessments and The Power Prediction of Wind Farm in Japan.
In this chapter, the wind assessment for wind farm project in Japan is explained with instance of Tomamae town’s wind
farm. The wind speed measurement is usually done by using a cup anemometer on the top of a mast (15-20m). In
general, the height of the anemometer is lower than the expected hub height of wind turbine to be used. In this study,
the Doppler sonic radar is also used for measuring the wind speed at hub height and above. The methods of prediction
based on two different experimental methods are discussed. The actual power output of wind turbine is compared withprediction results. The comparison between the low layer measurements (10,15m) and higher layer measurements(0-1000m) are discussed. The vertical velocity distributions have effect on the geographical shape and the surface
roughness.
Chapter 7; Experimental Study for Mutual Interference between Two Horizontal Axial Wind Turbines. (In Caseof Wind Tunnel Tests for Two kinds of Artificially Generated Flow Patterns)
In order to obtain the fundamental knowledge of turbulence and boundary layer profiles on wake interaction of HAWT’s,
extensive experiments were performed in a wind tunnel, considering two different flow patterns. This chapter, throughwind tunnel testing for two kinds of artificially generated flow patterns, investigates the interaction between two
HAWT’s and outlines the following points; (1)experimental analysis of wake behind HAWT for two different flow
patterns; (2) relationships between HAWT performances and two different flow patterns; (3)detailed investigation formutual interference between two HAWT’s. As the results, (1) The power co-efficient is not strongly affected by the flow
turbulence. (2) The wake region of the upper HAW’s is spread along the stream. (3) The velocity recovery ratio is bigger
when the turbulence intensity of the natural flow is higher. (4) The velocity distribution in the potential core region in
the wake of the HAW’s is extremely complicated, but in the well developed region, it becomes similar profile. Note thatspreading ratio depends strongly on the turbulence of the surrounding flow.
Chapter 8; Conclusion
The overall results and conclusion are summarized in this chapter.

103

Abstracts of Doctor’s Thesises

Master‑Slave System Characterized byHybrid Kinesthetic Sense Presentation ofReal and Virtual Force
Naoaki Tsuda(Division of System Engineering)
Keywords: Master-Slave System, Hybrid Kinesthetic Sense, Force Feedback,
Virtual Force, Environmental Reflection

Abstract
To attain comfortable maneuverability with master-slave systems, force feedback systems
have been studied in various ways. However, no reflective force is returned to the operators when
the slave robot works in free space, and doesn't have any contacts with the objects, in this case.
We sometimes intend the slave robot to be in or to come into favorite regions, and/or
intend the robot not to enter dangerous regions. It is necessary to notify the operator of the slave
robot's situation to meet the operator's intention.
To make the notification more effective, the authors proposed a method to present thekinesthetic sense as a hybrid of a contact-caused real force and a virtual force. The virtual force
reflects the slave robot's situation such as position and velocity, and the reflection helps theoperator to maneuver the slave robot in the environment with the favorite and/or dangerous
regions.
This thesis presents a design method of the proposed system, and confirms theeffectiveness of the system through tele-operating experiments.
M o to r
F o rce S e n so r

K

E n co d e r

V ir tu a l
Fv ir ＋
G u id in g
F o rce＋C a lcu la to r

M

B

<M a s te r>?ref<S la ve>
Fm

Fex t
?m

P o s it io n
C o n tro l le r

?s

−

−

＋

＋

P o s it io n
C o n tro l le r

Fig. Master‑Slave System Characterized by Hybrid Kinesthetic Sense Presentationof Real and Virtual Force

104

Abstracts of Doctor’s Thesises

Construction
In chapter 2, both the conventional force‑feedback master slave system and the proposedsystem that has virtual force feedback are explained.
In chapter 3, equipment that is used in this research is explained.
In chapter 4, an experiment is carried out. In the experiment, the proposed system isapplied on the driving system of a car, and the effectiveness of the system is confirmed.
In chapter 5, some experiment are carried out in order to confirm the effectiveness ofvirtual force feedback.
In chapter 6, designing method of the master‑slave system is proposed considering thesystem's stability. By using this method, several parameters can be tuned easily. The effectivenessis confirmed through positioning experiment.
In chapter 7, a case when the slave robot system is influenced by a disturbance is focusedon. There, a disturbance observer is introduced. The effectiveness is confirmed throughpositioning experiment.
In chapter 8, this thesis is concluded.

Author's publications[1]N.Tsuda, N.Kato, Y.Nomura and H.Matsui, "Master‑Slave System Characterized by Hybrid
Kinesthetic Sense Presentation of Real and Virtual Force", Journal of the Human Interface
Society, Vol.6, No.1, 2004.
[2]N.Tsuda, N.Kato, Y.Nomura and H.Matsui, "Development of Master-Slave System for
Magnetic Levitation", Proceedings of the International Conference on Machine
Automation(ICMA) 2000, pp.69-74, 2000, Osaka, Japan．
[3]N.Tsuda, N.Kato, Y.Nomura and H.Matsui, "Design framework of teleoperating system formagnetically levitated robot with force-feedback", Proceedings of SPIE (Telemanipulator andTelepresence Technologies VIII), Vol.4570, pp.25-33, 2002, Boston, U.S.A..
[4]N.Tsuda, N.Kato, Y.Nomura and H.Matsui, "Improvement of Virtual Force-Feedback
Teleoperating System Considering a Disturbance", Proceedings of the 3rd China-Japan
Symposium on Mechatronics(CJSM2002), pp.167-172, 2002, Chengdu, China.

Abstracts of Doctor’s Thesises

105

Study on computer-supported system for mass classes
Naoki Morita(Aducational Technology, Division of Systems Engineering)
Keyword: Degree of Understanding, Description Answer, e-learning, Natural Language Processing

1. Introduction
It is important for students to ask about the issues that they do not comprehend in lectures.
Nevertheless, most students in Japan seldom do so. It makes teachers hard to know whether students
comprehend or not (see Kita, et al. 2001.)
To grasp students' comprehension, teachers often give short tests in lectures. In short tests, theuse of description-answer style brings better grasp than that of multiple-choice answer style. Because,students must describe their answers with their own words. However, in a large class, it is hard for theteacher to check all description-answers during the lecture. As a result, they cannot give appropriate
advices and improve students' comprehension immediately.
2. Idea
If teachers could grasp students' comprehension (even though roughly,) they could immediately
modify the lectures according to it.
We propose a real-time description-answer short test system to grasp their comprehension in alarge class. The system classifies students' description-answers into several groups of similar contents,
since it is easier for teachers to check all classified answers than to do all unclassified ones.
To grasp students' comprehension, teachers need to know major patterns of the answers. In thispaper, we assume that similar answers include same keywords. The system divides answers exclusively
using the keywords contained in a lot of answers.
3. The method of classifying answers
Based on this idea, the system classifies answers as the following procedure. First, the system
extracts candidates of keywords from the answers. Next, it chooses keywords from the candidates andclassifies the answers according to the keywords. After that, teachers modify groups appropriately. The
details of each process are described as follows.
・Extracting candidates of keywords
Since words in Japanese sentences are not separated by spaces, using the Japanesemorphological analyzer “Chasen” (see Matsumoto, 2000,) the system extracts words from the answers
and makes them candidates of keywords.
・Classifying answers into groups
The system calculates the weight of each candidate according to its frequency in the
unclassified answers. It chooses the candidate with the heaviest weight as the keyword. It gathers all
unclassified answers including the keyword into a group. By repeating this process, most answers areclassified into several major patterns.
We provide two manual operations to modify groups appropriately.
Adjusting the weight of each candidate
The system sometimes may not choose keywords that teachers expect. We provide a manual
operation that teachers are able to adjust the weight of candidates. Increasing the weight of a candidate
enhances the possibility of choosing the candidate as a keyword. Decreasing the weight reduces it.
・106

Abstracts of Doctor’s Thesises

・Specify multiple keywords for one group
Making a group by using single keyword may bring the group with various contents. Such agroup can be divided into several appropriate groups by using multiple keywords simultaneously. We
provide a manual operation to specify multiple keywords for a group with unique content.
4. Real-time description-answer short test system
We implemented the real-time description-answer short test system on Web, and used it in thelecture, "How to use the university library" which has 90 students.
The teacher asked, “How do you find Japanese books written about computer literacy in the
Mie university library?" The purpose of the question was to make sure whether students know thefollowing two issues or not. First, using the search-engine OPAC (On-line Public Access Catalog) is
necessary to find required books in the Mie university library. Second, to find Japanese books, keywords
for the OPAC must be written in Japanese.

A
B
C
D

A: Searching ‘computer literacy (in Japanese)’with OPAC (11)
B: Writing computer literacy (in English) in thetitle area of OPAC and searching (15)
C: Using the OPAC of Mie University (17)
D: Searching at the library (14)Italic words show the keywords.
The number in each pair of parentheses shows thenumber of answers in each group.

Figure 1: Result of classification

The result shown in the figure1, the teacher adjusting the weight three times and specifies
multiple keywords two times. These operation was not a burden on the teacher.
The answers in the group A correspond to the answer that the teacher expected, because they include theboth important keywords “OPAC” and “computer literacy (in Japanese).” The answers in the group B
included the expected keyword “OPAC” and the unexpected keyword “computer literacy (in English).”The teacher advised to use the word “computer literacy (in Japanese)” to find Japanese books. The
teacher gave the appropriate comments on the answers in the other groups, similarly.
5. Conclusion
We proposed a real-time description-answer short test system for teachers to be able to grasp
students' comprehension in lectures. The system immediately classifies students' description-answers
according to keywords extracted from them. The classified answers help teachers to grasp theircomprehension. We applied this system to some large classes. We found this system was effective forgrasping the comprehension.
Author’s publications[1] MORITA Naoki, KITA Hidehiko, TAKASE Haruhiko, HAYASHI Terumine, “多人数講義における記述式解答の内容を即時に把握するためのシステム”, CIEC 会誌 コンピュータ&エデュケー
ション Vol.13, pp.103-109, 2002
[2] MORITA Naoki, KITA Hidehiko, TAKASE Haruhiko, HAYASHI Terumine, “記述式の解答を即時に講師が把握するためのシステム”, FIT2002 情報科学技術フォーラム 情報技術レターズ
vol.1, pp.233-234, 2002【FIT2002 論文賞受賞】[3] MORITA Naoki, KITA Hidehiko, TAKASE Haruhiko, HAYASHI Terumine, “A Method of
Immediately Classifying Description-Answers in a Large Class”, International Conference on
Computers in Education 2003, Proceedings CD-ROM 130-132, 2003

107

Abstracts of Doctor’s Thesises

Studies on Pulverization of Fine Solid Particles by Super Sonic Jet
Flow and Pneumatic Classification of Ultra Fine Solid Particles
Hiroshi Morimoto†(Fluid and Thermo Engineering, Division of Systems Engineering)
Keywords : Fine and ultra fine solid particles, Gas-solid flow, Particle laden super sonic jet flow,
Pulverization, Jet mill, Classification, Size distribution
1. Introduction
Recently, there are great requirements for ultra fine solid particles powder, in the fields of advanced
materials, for example, electric parts in IT industry. Especially, the diameter control of fine powder isrequired. A super sonic jet mill or pneumatic type ultra fine powder classifier is used widely for thepulverization and classification of various kinds of fine particles in many powder manufacturing processes.
In pulverization by a jet mill, the improvement of pulverization efficiency is very important, because the jetmill consumes a large operating power. In classification by a pneumatic type powder classifier, there is no
study on the flow characteristics which realizes a high performance for classification of ultra fine powder.
In this study, a new super sonic jet nozzle with a rectangular cross section is proposed and the flow andparticle acceleration characteristics are investigated experimentally by velocity measurement and flow
visualization. Numerical analysis is also carried out for reference. It was known that the new super sonic jet
nozzle has a high performance for particle acceleration, namely for improvement of pulverization efficiency.
A new pneumatic type ultra fine powder classifier is also proposed and the relation between theperformance and the flow characteristics is investigated by velocity measurements and flow visualization. The
new classifier has a large swirling flow velocity, and then can classify ultra fine particles with sub-µm accuracy.

D50 [μm]

2. Results and Discussions
2.1 New super sonic jet nozzle with a rectangular cross section
Figure 1 shows a new supersonic jet nozzle with a rectangular cross section. In general, conventional
supersonic nozzle has a round cross section then the flow spread three-dimensionally. But, new one has arectangular cross section and then the flow spread two-dimensionally and the decay of the flow velocity will be
suppressed. The particle acceleration performance and flow characteristics are examined experimentally byhigh-speed camera and Schlieren method, and the pulverization efficiency of fine particle is also tested for a few
materials. The expansion angle and supplying air pressure are varied θi = 6°to 20°and P0 = 0.2 to 0.6,
respectively. It was known that the new supersonic nozzle has a high particle acceleration performance than theconventional one.
Figure 2 shows one example of the pulverization efficiency η of iron powder of mean diameter D50 = 62.4µm
and density ρ= 7.85g/cm3 which is obtained by a closed-circuit pulverization system. The new supersonic jet
nozzle has 1.53 times processing rate of the conventional
nozzle for the same products of D50 = 30µm. It has a high50
pulverization performance, especially for a large density
C : Cylindrical nozzle
R : Rectangular nozzle
materials, copper, iron and ruthenium.
40
30

20

F

sonic jet nozzle
Pulverization efficiency†Nippon Pneumatic MFG. CO., LTD
2.2 New pneumatic type ultra fine powder classifier

ig.1
Ne
w
sup
er
Fig.2

Particle : Iron
D p : 62.4µm
P 0 : 0.6MPa

10◆ : STD (C)■ : BF (C)▲ : θ i ＝11° (R)(R-Improvement type)ρ : 7.85g/cm3
0
0

20
40
Pulverization Efficiency, η ×10-8
2

3{[kg/hr]/[kgf/m ][m /hr]}

60

108

Abstracts of Doctor’s Thesises

Figure 3 shows a new pneumatic type ultra fine powder classifier. It has conic shaped classification zone inorder to generate a strong rotational flow. It was intended to realize an ideal flow field to give a large centrifugal
force for all supplied fine particles in order to classify accurately in ultra fine powder. The flow condition was
confirmed by flow visualization and observation by the tuft grid and oil dot methods and the measurement of air
velocity distribution by a yawmeter with single hole. The classification performance was examined for somekinds of fine particles.
Figure 4 shows one example of the classification, partial separation efficiency, of calcium carbonate. The
cutting size is Dpc = 0.95µm and sharpness index is SI = 1.98 when loading ratio is LR = 0.042, and then it can besaid the classification performance is very fine. For some other materials, the good classification performancecan be also obtained as follows. For tungsten dioxide, toner and barium titanate, Dpc = 1.23, 2.80, 2.45µm and
SI = 1.22, 1.33, 1.16, respectively.
100

100

CoarseUnder size distribution [%]

80

60

60

40

40
Material ： Calcium carbonate
Cutting size ： 0.95µm
SI =1.980
Feed rate ： 20kg/hr
LR =0.042

20

Partial separation efficiency [%]

Fine
80

20

0

0
0.1

1

10

100

Particle size, D p [μm]Fig.3 New ultra fine powder classifierFig.4 Classification of calcium carbonate

3. Concluding remarks
3.1 New super sonic jet nozzle with a rectangular cross sectioni) The new super sonic jet nozzle has about 1.7 times a high performance for particle acceleration than that of
the cylindrical nozzle.
ii) The numerical analysis agrees well with the flow visualization by Schlieren method.
iii) The new super sonic jet nozzle has a high pulverization performance for a large density material, copper,
iron and ruthenium.
3.2 New pneumatic type ultra fine powder classifieri) The flow introduced into the classification zone passing through the louvers, which were set evenly on
the circumference at the bottom of the conic, is divided into two flows which flow on the upper and lower
surfaces. The upper flow is swirling up along the upper surface and after turning at the top of the conic it isexhausted from the exit.
ii) The descending flow area near the center forms the maximum swirling velocity (the fastest tangential
velocity) region in the classification zone.
iii) The new pneumatic type ultra fine powder classifier can classify the ultra fine powder very accurately.
iv) The approximate theory for the cutting size can express the experimental one well.
Author’s publications[1] H. Morimoto, N. Oda, H. Terada, and T. Shakouchi, Inner Flow of Pneumatic Powder Separator and
Separation Efficiency, Trans of JSME, No.973-1, pp.249-250, Mar., 1997[2] H. Morimoto, Air Pulverizing, Classification and Dispersion, Seminar’s Materials of Tokai Branch of The
Heat Transfer Society of Japan, pp.39-54, Oct., 2000
[3] H. Morimoto, T. Shakouchi, Study on Flow Characteristics in and Classification Efficiency of PneumaticType Ultra Fine Powder Classifier, Trans. of JSME, 68-668 B, pp140-146, Apr., 2002
[4] H. Morimoto, T. Shakouchi, Classification of Ultra Fine Powder by a New Pneumatic Type Classifier,Powder Technology, Vol.131/1, pp71-79, Nov., 2002
[5] H. Morimoto, T. Shakouchi, Flow Characteristics and Classification Efficiency of New Pneumatic TypeUltra Fine Powder Classifier, 4th World Congress on Particle Technology, CD-ROM, Jul., 2002

Abstracts of Doctor’s Thesises

109

Automatic text classification of English newswire articles based on
statistical classification techniques
Zu Guowei†
Keywords：automatic text classification, principal component analysis, projection distance, variable transformation

1. INTRODUCTION
The basic process of automatic text classification is learning a classification scheme from training examples then using it toclassify unseen textual documents. In this paper, we focus on techniques of feature transformation such as the normalization
to the relative word frequency, the principal component analysis (PCA) and the power transformation to improve theaccuracy and the speed of automatic text classification.
In order to evaluate the effectiveness of the variable transformation and the principal component analysis, Several
classification techniques based on the Euclidean distance, Fisher’s linear discriminant function, projection distance, modified
projection distance and the support vector machine (SVM) are employed in the classification test for the English text
collection (the reuters-21578 ).
Furthermore, we perform automatic text classification experiments for English newswire articles to study on therelationships between the accuracies of OCR and the text classification employing the statistical classification techniques.

2. THE BASIC TECHNOLOGY
In this research we employed the statistical classification technique for classifying a feature vector composed of frequenciesof lexicon words that appear in a text. The approach is learning a classification scheme from labeled training examples thenusing it to classify unseen textual documents. Several classification techniques based on the Euclidean distance, Fisher’slinear discrimination function, projection distances, and the support vector machine (SVM) are employed in the classification
test for the English text collection (the reuters-21578).
A drawback of the statistical classification technique is that the dimensionality of the feature vector can increase together
with the lexicon size. For example, the lexicon size and the feature dimensionality grow to 34,868 for Reuters-21578 articles,
which requires enormous computational time and storage for the text classification. To solve this problem we need to employ
a statistical feature extraction technique which extracts small number of features with high separability to reduce the feature
dimensionality without sacrificing the classification accuracy. In this research the dimension reduction based on the principal
component analysis (PCA) was employed.
The word frequency is widely used as the basic feature in the statistical text classification approach. Since the absolute
frequency depends on the length of the text, the relative frequency which does not depend on the length is also employed.
Because the relative frequency does not depend on the text length, the within-class variance of the relative frequency issmaller than the absolute frequency. Therefore we can expect that separability in the feature space and the classification rate
is improved when the relative frequency is employed
Another variable transformation, the power transformation is employed to improve the classification accuracy. Thistransformation improves the symmetry of the distribution of the frequency which is noticeably asymmetric near the origin.

3. THE CLASSIFICATION EXPERIMENTClassification experiments were performed to comparatively evaluate the feature extraction and classification techniques
using the data collection Reuters-21578, which is composed of 21578 articles manually classified to 135 categories. In theexperiments total of 750 articles, 150 articles/category randomly selected from five categories (acq, crude, earn, grain, trade),were used.
Fig.1 shows the relationship between the average classification rate and the dimensionality of the feature vector composedof the absolute word frequencies. Fig.2 shows the classification rate at the optimal feature dimensionality. And Fig.3 shows
the relationship between the text classification rate and the word recognition rate.
†

Division of Systems Engineering, Mie University

110

Abstracts of Doctor’s Thesises
absolute f req.
absolute f req.with power trans. (v = 0.5)
relative f req.
relative f req. with power trans. (v = 0.5)

10 0

95
95

classification rate (%)

average classification rate(%)

90
85
80
75
modified projection distanceSVM-RBF
SVM-linear
projection distancelinear discriminant function
Euclidean distance

70
65

90

85

80

75

60

70

10

200

500

800

1500

dimensionality

Euclideanlinearprojection

modifieddistance

discriminantdistance

projection

function

SVM-Linear

SVM-RBF

distanceclassifie r

Fig. 1. Classification rate vs. dimensionality (absolute frequency)

Fig. 2. Classification rate at the optimal feature dimension

text classification rate（％）

100

90

80

70

Euclidean distancelinear discriminant function
projection distanceSVM-RBF
SVM-linear
modified projection distance

60

50

50

55

60

65

70

75

80

85

90

95

100

word recognition rate(%)

Fig.3 The relationship between the text classification rate and the word recognition rate

4. THE RESULTS OF EXPERIMEN
The results of experiment are summarized as follows:(1) the principal component analysis drastically reduced the feature dimensionality without sacrificing the classification
performance,(2) the normalization to the relative frequency followed by the power transformation improved the classifier performance
significantly,(3) considerably high classification rate for the transformed features was achieved by the modified projection distance, and(4) the text classification rates of all classification techniques were not deteriorated significantly until the word recognition
rate was deteriorated to 95% or 80%, respectively. And the modified projection distance outperformed the others in theaccuracy and the robustness of the text classification in this experiment.
AUTHOR’S PUBLICATION
1. Guowei Zu, Wataru Ohyama, Tetsushi Wakabayashi, Fumitaka Kimura, “Automatic text classification of English
newswire articles based on statistical classification techniques” IEEJ Trans. EIS, Vol.124, No3, pp.852-860, 2003
2. Guowei Zu, Wataru Ohyama, Tetsushi Wakabayashi, Fumitaka Kimura, “Accuracy improvement of automatic textclassification based on feature transformation” DocEng’03 (ACM Symposium on Document Engineering 2003),
pp.118-120,November 20–22, 2003, Grenoble, FranceAbstracts of Doctor’s Thesises

111

LCA Consolidated Evaluation of IndonesianElectricity Generation Systems
Anugerah Widiyanto(Energy Systems Design, Division of Systems Engineering)
Keywords: Power plants, Energy conversion, Environmental impacts, Life cycle assessment, Life cycle
inventory, Indonesia, Electric generation systems, LCA-NETS method

1. Introduction
The life cycle inventory (LCI) data of the electric power generation plays a vital role on LCIs of theindustrial products. However there are no formal life cycle assessment (LCA) studies in Indonesia so far due tolimited number of LCA expertise and lack of sufficient databases relevant to domestic conditions. Therefore, theaim of this study is, firstly to introduce life cycle assessment methodology for Indonesian electric power
generation systems, secondly to establish LCI data for electricity grid mix of Indonesia, and finally, to evaluate
the environmental from a life cycle impact assessment (LCIA) point of view.
A model was developed for the analysis, which had advantages of being based on new reliable data
reflecting the current status in Indonesia with a combined method of process analysis and input-output analysis.
Using the developed model, the life cycle emissions per kWh of electricity of CO2, SO2, NOx, CO, CH4, NMHC,
N2O, Dust (SPM), Ni, As, Cd, Cr, Hg, Pb, and Zn were studied in a cradle-to-grave manner. The proposed
LCA-NETS (Numerical Eco-load Total Standard) method is used as life cycle impact assessment method. As theresults the LCA evaluations are discussed for further ecological improvement.
2. Methodology
2.1. Life cycle inventory data
In this LCA, the life cycle emission factor LCEi was used as an index to evaluate the selected emission
characteristics of the power generation technologies from the lifecycle viewpoint. The amount of emissions
released across the entire life cycle to generate net 1 kWh of electricity is defined as follows:∑ Df i + Dc i + Do i + Dd i
LCE i = i(1)
Eg
Where: Df is direct discharged emission caused by the combustion of fossil fuels in power plants. Dc isdischarged emission associated with the construction of plants required in the system studied. Do is discharged
emission for operation and maintenance for the plants. Dd is discharged emission by decommissioning the plants.
Dc, Do and Dd are here referred to as indirect discharged emissions. Subscript i indicates the type of emission(CO2, SO2, NOx, CO, CH4, NMHC, N2O, Dust, Ni, As, Cd, Cr, Hg, Pb, Zn). Eg is net output of electricity during
a lifetime of a power plant. Net output is the amount of electricity supplied to the grid excluding the energy
consumption for the operation of the plants.
2.2. Life cycle impact assessment method
In the LCA-NETS method, the analyzation of an environmental load is expressed by standardizing on the basisof the L-R Tolerance Balance Theory, which balances the maximum tolerable value that the Loader can emit orconsume, and the maximum value that the Receiver affected by the load can tolerate. This approach has the
additional feature of allowing a complete quantitative evaluation of the various environmental loads in the newunits [NETS]. The L-R Balance Theory defines, first of all, the Maximum Permissible Eco-load Value (MEVj)[NETS] for given environmental load (j) tolerated by the ecosystem on the Receiver side. In this scheme, thetolerable value for a person is determined as 100 [NETS], because the tolerance level has reached 100%, and unlesssome measure is taken, the standard of living we have enjoyed so far cannot be maintained. When the maximum
tolerance value is Pj (kg, kWh, m3, etc.), according to the L-R Tolerance Balance Theory,
Pj・ELMj = MEVj
3

(2)

here, ELMj [NETS/kg, kWh, m , etc.] (Environmental Load Module) is the conversion coefficient connecting Pj[kg, kWh, m3, etc.] and MEVj [NETS], and also refers to the environmental load consolidated basic value for unit
emission or consumption.

Abstracts of Doctor’s Thesises

80%
60%
40%
20%

Geothermal
Oil GTNG steam
Oil CCJava

Indonesia

Region XI

Region X

Region IX

Region VII

Oil steam
NG GT

Region VIII

Region V

Region VI

Region III

Region IV

Region I

Hydro
DieselRegion II0%
Outside Java

Share of electricity production

.

100%

Coal steam
NG CC

1259

Fig. 1: Share of electricity production per region
1500

708
Indonesia

856
Region XI

690

838
Region X

Java

844
Region IX

593

764

911

726

612

835
Region I

900

778

1200

Outside Java

302

600
300

Region VIII

Region VII

Region VI

Region V

Region IV

Region II

0
Region III.

3. Results and Discussion
In this study, the life cycle inventory (LCI) for
electricity grid system in Indonesia was developedand evaluated based on PLN data of fiscal year
2001. Figure 1 shows the composition of electricity
generation in Indonesia classified by power plant
type. Figure 2 presents a comparison of the life
cycle GHG emissions and its composition perregion. As the LCI result, the average amount ofemission intensities [kg/kWh] for main emissions ofCO2, SO2, NOx, CO, CH4, NMHC, N2O, Dust
(SPM), Ni, V, As, Cd, Cr, Hg, Pb, Zn were 7.2×10-1,
2.4×10-3, 3.0×10-3, 1.2×10-4, 4.5×10-3, 7.2×10-4,
2.3×10-5, 2.7×10-4, 7×10-7, 1×10-6, 2×10-8, 2×10-9,
2×10-8, 1×10-8, 4×10-8, and 1×10-7, respectively.
Compared to Japan, these values of CO2, SO2, NOx,
CO, CH4, NMHC, N2O, Dust (SPM) are 167%,
615%, 714%, 92%, 321%, 218%, 209%, 1000%,
respectively those of Japan. As for heavy metals
emissions, compared with Japan, these values areabout 489% to 3258%. And the average
environmental load consolidated value that has been
calculated using LCA-NETS method for Indonesian
grid electricity system is found of 2.7×10-3[NETS/kWh].

LC GHG emissions [g-CO2/kWh]112

4. Concluding Remarks
Hydro
Geothermal
Oil steamNG steam
Coal steam
We have conducted a quantitative analysis ofDieselOil GTNG GT
Oil CCNG CC
the environmental load produced by energy systems
Fig. 2: Life cycle GHG emissions per region
such as various kind of power plants andco-generation systems using the LCA-NETS
approach developed by the authors’ laboratory. We also have evaluated the environmental load produced byvarious types of energy system in terms of environmental load consolidated values that cover the entire LC
phases. This result could be useful for further LCA research.
Author’s main publications[1] A. Widiyanto, S. Kato, N. Maruyama, Environmental Impact Analysis of Indonesian Electric Generation Systems, JSMEInternational Journal, Series B, Vol. 46, No. 4 (November 2003), pp. 650-659.
[2] A. Widiyanto, S. Kato, N. Maruyama, Y. Kojima, Environmental Impacts of Fossil Fuel Fired Co-Generation Plants
Using A Numerically Standardized LCA Scheme, ASME Transactions, Journal of Energy Resources and Technology, Vol. 125,
No. 1 (March 2003), pp. 9-16.
[3] A. Widiyanto, S. Kato, N. Maruyama, A LCA/LCC Optimized Selection of Power Plant System with Additional Facilities
Options, ASME Transactions, Journal of Energy Resources and Technology, Vol. 124, No. 4 (December 2002), pp. 290-299.
[4] S. Kato, N. Maruyama, Y. Nikai, H. Takai, A. Widiyanto, Life Cycle Assessment Estimation for Eco-Management of
Co-Generation Systems, ASME Transactions, Journal of Energy Resources and Technology, Vol. 123, No. 1 (March 2001),
pp. 15-20.
[5] A. Widiyanto, S. Kato, Life Cycle Assessment of Power Generation Systems, Journal of Fusii, Special Edition, No. 6(March 2000), pp. 72-76.
[6] S. Kato, N. Maruyama, Y. Nikai, H. Takai, Y. Kojima, A. Widiyanto, Quantitave Standardization of Various Global
Environmental Loads and Its Applications to Eco-load Operation Scheme of Co-generation Systems (in Japanese), Journal of
Fluid and Heat Eng. Research, Vol. 34, No. 2 (December 1999), pp. 37-44.
[7] A. Widiyanto, S. Kato, N. Maruyama, Optimizing Selection of Appropriate Power Generation Systems in Indonesia By
Using Distance Based Approach Method, ASME Transactions, Journal of Energy Resources and Technology, Vol. 126, No.1,(in press).
[8] A. Widiyanto, S. Kato, N. Maruyama, Development of Decision Model for Selection of Appropriate Power Generation
System Using Distance Based Approach Method, JSME International Journal, Series B, Vol. 47, (in press).
[9] S. Kato, A. Widiyanto, Environmental Impact Consolidated Evaluation of Energy Systems by a LCA-NETS Scheme,
Elsevier, Energy, The International Journal, Vol. 29, (in press).
[10] A. Widiyanto, S. Kato, N. Maruyama, LCA Consolidated Evaluation of Indonesian Electricity Grid System (Part 1:
Evaluation of Green House Gas Emissions from Power Generation Systems), The International Journal of Life Cycle
Assessment, (accepted).
[11] A. Widiyanto, S. Kato, N. Maruyama, LCA Consolidated Evaluation of Indonesian Electricity Grid System (Part 2:
Development of Life Cycle Inventory), The International Journal of Life Cycle Assessment, (accepted).

Abstracts of Doctor’s Thesises

113

A Study on Harmonics Suppression of PMSM
Using Repetitive Control and Application to
Improvement of Sensorless Control Performance
Jeong-Seong Kim†
Key Word : Permanent magnet synchronous motors, Harmonic currents,
Repetitive control, Sensorless Control

Ⅰ. INTRODUCTION
In recent years, PMSMs (Permanent Magnet Synchronous Motor) have been widely used for industry
applications and home electric appliances. PMSMs are generally driven by the vector control system based on
the current control. However, there are some harmonic components in the current control loop of vector control
system. These harmonic currents bring about problems such as decrease of control performance and vibrationof the motor, and they have bad influence on sensorless control.
In this paper, we propose a control method suppressing all harmonic current components using therepetitive control. Furthermore, in this paper, we show that the proposed control system can be used for
improvement of position/velocity sensorless control performance. The one of important features of theharmonics suppression control system is that harmonic components of not only currents but also voltage
commands can be suppressed. So, it can be expected that estimation ability of the sensorless control system
would be improved.

Ⅱ. CONFIGURATION OF THE CONTROL SYSTEM
Fig.1 shows the configuration of the proposed harmonics suppression control system. The compensation
signal learning process to suppress harmonics in the current control loop is as follow. First, harmonic**component vdq (h ) extracted from d-q coordinate voltage command vdq is put into the repetitive compensator(N memories) as a source of compensation signal. In the repetitive compensator, the input signal is added to the
output one delayed by one cycle. k1 is set as 0, that is, the proposed control system doesn’t need to adjust thephase of compensation signal for the stabilization of the repetitive control. The compensation signal vdq _ c*made through above process is added to original voltage command vdq . The learning process forcompensation signal is repeated until
Repetitive controller
harmonics are suppressed fully, suppressing
Time leading
Repetitiveelement
compensatorharmonics in the current control loop andRemovale −sTof DCbuilding up the compensation signal. Removale
Sw1of DC component is carried out by HPF[ HPF(s) = τs / (τs + 1), (1 / τ = ω re ) ].
**
**
*
*
vuvw
**
vdq
vdq
ω re* Velocity idq
vαβCurrent
According as harmonic components in
αβ/uvw
controller
controller
INV.
dq /αβ
*
*
*
vαβ
v dq
are reduced, iαβ and vαβnearlydq /αβapproach
to
the
sine
wave
as
shown
in
Fig.2.
iαβ
idq
iuvw
*
uvw/αβWith these iαβ and vαβ , we construct
αβ /dqθˆsensorless control system which is based on
PMSM
Position
the extended EMF disturbance observer as an
estimator
EEMFê
Disturbanceω̂ reexample. As a result of suppression harmonics,
Velocity
ObserverDCG
estimator
we can have margin in the pole assignment of
Sensorless control systemobserver so that the performance of sensorlessFig.1 Configuration of the proposed control system
control can be improved.
r

k1
sTr
N

I

†

Dept. of Electrical and Electronic Eng., Mie University

114

Abstracts of Doctor’s Thesises

Ⅲ. EXPERIMENTAL RESULTS
20ms/div
Fig.2 shows experimental results when
20ms/div
electrical rotation velocity is 100[rad/s] and thevα*vα*
cut-off frequency of current control system is1500[rad/s]. From Fig.2, we can confirm that the
v β*
v β*
proposed control system excellently suppressesiα
iα
harmonic currents, so currents of the α β axis
become almost sine waves. Fig.3 shows theiβ
iβ
experimental results of senseless control drive.
(a) without repetitive control(b) with repetitive control
Fig.3(a) and (b) is the case without repetitive control,
Fig.2 Waveforms when with and without repetitive control
when observer pole is placed at 0.25 ω̂ re and(100rad/s, Ch1,2:100V/div Ch3,4:2.5A/div)
2.0 ω̂ re respectively. Fig.3(c) is with repetitive
control, when observer pole is 2.0 ω̂ re . Left side of<Steady state >< Transient state>
the figure is result of steady state drive, when
100 ms/div
1 s/div
velocity is of 50rad/s. Right side of the figure isν d*ω re [80 rad/s /div]
acceleration and deceleration drive, that is step [10 v/div]
changes between 50rad/s and 200rad/s. From
[80 rad/s /div]∆ θ reω̂ reFig.3(a) and (b), we can confirm performance [2 ﾟ/div][4 rad/s /div]∆ω retrade-off caused by the pole assignment. However,∆ω rein case that observer pole is assigned largely [1rad/s /div](2.0 ω̂ re ) after harmonic suppression with repetitive(a) without repetitive control ( small observer pole : α= 0.25 ω̂ re )control, it is possible to enhance the estimation
100 ms/div
1 s/div*
ability as good as Fig.3(a) on the steady state, [10νv/div]dω rekeeping estimation ability on the transient state as
shown in Fig.3(c).
∆ θ reω̂[2 ﾟ/div]

re

∆ω re

Ⅳ. CONCLUSIONSWe proposed an improving method of
sensorless control performance for the PMSM by
suppression of harmonic components of the vector
control using the repetitive control. The sensorless
control system for the PMSM was constructed basedon the observer with the current and voltage
command whose harmonic components were
suppressed by the repetitive control. As a result, we
could have a margin in pole assignment of theobserver so that the performance of sensorless
control could be improved. The experiments showedthat the proposed method is effective.

∆ω re[1rad/s /div](b) without repetitive control ( large observer pole : α= 2.0 ω̂ re )100 ms/div

ν d*[10 v/div]

1 s/div

ω re∆ θ re[2 ﾟ/div]

ω̂ re
∆ω re

∆ω re
[1rad/s /div](c) with repetitive control ( large observer pole : α= 2.0 ω̂ re )Fig.3

Improvement of position and velocity estimation
ability by suppression of harmonic components

Author’s main publications[1] Jeaong-seong Kim，Shinji Doki，Muneaki Ishida：“Improvement of IPMSM Sensorless Control Performance by Suppressionof Harmonics on the Vector Control Using Fourier Transform and Repetitive Control”，CD-ROM of the 28th International
Conference on Industrial Electronics, Control and Instrumentation，(IECON’02, Sevilla, Spain)，(2002/11)[2] Jeaong-seong Kim，Shinji Doki，Muneaki Ishida：“Suppression of Harmonic Current in Vector Control for IPMSM by
Utilizing Repetitive Control”，Proceedings of the 2002 IEEE International Conference on Industrial Technology, (ICIT’02,
bangkok, Thailand)，Vol.1，pp.264/267，(2002/12)[3] Jeaong-seong Kim，Shinji Doki，Muneaki Ishida：“Harmonics Suppression of PMSM Using Repetitive control andApplication to Improvement of Sensorless Control Performance”，CD-ROM of the 29th International Conference on Industrial
Electronics, Control and Instrumentation，(IECON’03, Roanoke, USA)，(2003/11)[4] Jeaong-seong Kim，Shinji Doki，Muneaki Ishida：“Improvement SensorlessControl Performance for IPMSM by Suppressionof Harmonic Current with Fourier Transform and Repetitive Control”，Trans. IEE of Japan, Vol.123-D, No.10, pp.1176/1184(2003/10)

115

Abstracts of Doctor’s Thesises

Study of Trenchless Buried Objects Survey and Non-Destructive Testing Method for
Underground Tele-Communication’s Equipment
Yoshikazu Sudo†
Keyword: Underground Radar, GPR, Non-Destructive Testing, Frequency analysis, Pattern recognition

1. INTRODUCTION

Ground penetrating radar offers an effective means for conducting underground surveys at relatively shallow depths.
The problem, however, is that skill is required to interpret the resulting imagery. This makes it difficult to process large
volumes of data quickly, which has impeded expansion of the range of use of ground penetrating radar.
The authors have investigated methods to isolate only the specific signals of buried objects by using the previously
identified frequency domain characteristics of ground penetrating radar wave reflections in order to simplify image
interpretation and to enable speedy processing of large volumes of data [1]-[3]. The authors had recognized that the reflected
waves from buried pipes and from underground cavities are distributed to specific areas in the frequency domain, andpointed out the possibility of isolating the signals from buried pipes and cavities. They had further pointed out that buried
objects and cavities differ from each other in the frequency feature distributions with respect to the hyperbolic curves ofsignals , that is, their distributions with respect to the directional angle of received waves.
This paper describes aerial experimental results of radar surveys of steel pipe and steel plate conducted in order to study
their characteristics as part of a wide range of basic study to determine the reasons for the difference in frequency domaincharacteristics between buried pipe and underground cavities.
2. EXPERIMENTAL APPARATUS and CONDITIONS

Figure 1 shows the experimental conditions. A semicircle as shown in Figure 1 was drawn on the ground surface andthe ground penetrating radar antenna was placed at its center. Two measuring lines—line A, on the semicircle, and line B, atangent line parallel to the antenna—were drawn. The directional angle θ was set as shown in Figure 2, and objects wereplaced at the points where a line in the radial direction intersects with lines A and B. Two objects were used, a 100-mm
diameter steel pipe and a 500 X 1000-mm steel plate. The steel plate was fixed so that its flat surface was oriented verticallyand its long side was parallel to line B.
The waves from the ground penetrating radar reflected from the steel pipe and steel plate, respectively, were observed
under these conditions. The system involves a function to isolate only the signals of the observed waves reflected from theobjects, from which the corresponding frequency spectra were calculated, and their central frequencies and half-widths were
derived.
3.RESULTS and DISCUSSION
Figure 2 shows the observed central frequency and half-width online A. In the case of the steel pipe, the central frequency showed
little change until the directional angle reached the vicinity of 30°.
The half-width tended to increase as the directional angle increased
from 0°. When the directional angle exceeded 40°, each feature
value showed a rapid drop. It is considered that this drop has been
resulted from the rapid decrease in energy owing to the directivity ofthe transmitted electromagnetic pulse, and it is unlikely to be a
distinctive characteristic of the steel pipe. In the case of the steel
plate, on the other hand, both feature values seemed not to depend on
the directional angle. Figure 3 shows the observed central
frequency and half-width on line B. Where both the central
frequency and half-width tended to increase with the directional†AIREC Engineering Co.

Line B
３ｍ
θ

ObjectLine AGPR antenna
Object : Steel pipe

φ100

Steel plate 500×1000, t=3.0 (mm)Fig.1 Experimental Condition

116

Abstracts of Doctor’s Thesises

400
350
300
250
200
150
100
0
20
40
60
Directional Angle (degree)
Fig2. Relationship of Fc and Hw to
Directional Angle, line A

Fc (pipe)
Hw (pipe)
Fc (plate)
Hw (plate)Center Frequency andHalf-width (MHz)Center Frequency and Halfwidth (MHz)angle up to about 30° in the case of the steel pipe, they showed the opposite tendency to decrease in the case of the steel
plate.
In Figures 2 and 3, the central frequency and half-width in the vicinity of a 0° directional angle both show larger values in
the case of the steel plate. This is thought to be because, whereas the transmitter antenna is markedly larger than the steel
pipe, it is about the same size as the steel plate, and also because the steel plate is directly opposed to the antenna, so that
there was less disorder in the reflected wave.
Tests previously conducted by the authors showed both the central frequency and the half-width reaching higher levels
with a plate-shaped cavity than with a buried pipe. Those findings closely match the present results. In the case of an
actually buried pipe, the signals from showed a tendency for both the central frequency and half-width to decrease as theantenna approached a point directly above the buried pipe, while that in the case of a cavity showed the reverse increasing
tendency. The present results match closely with these observations.
The difference observed in the present experiment is thought to originate from the shape difference between the steel pipeand steel plate, since both are made of the same material. This suggests that it is possible to recognize shapes of objects
using the present results. Clarification of this possibility, however, will require more detailed study that varies the shapes,
sizes, and materials of the objects.

400
350
300
250
200
150
100

Fc (pipe)
Hw (pipe)
Fc (plate)
Hw (plate)

0
20
40
60
Directional Angle (degree)
Fig.3 Relationship of Fc and Hw to
Directional Angle, line B

4. CONCLUSION
Experimental investigation of the relationship between the central frequency and half-width of a reflected wave and its directional angle
when using ground penetrating radar aerially yielded the following observations:(1) The central frequencies and half-widths of waves reflected from pipe and steel plate tend to differ. This tendency coincides with theresults from actual buried objects such as steel pipe and steel plate.
(2) The reason for this tendency to differ is thought to be the different shapes of the objects.

(3) The current results confirmed the possibility that shapes of objects buried in the ground could be recognized, but this will
require further, more detailed study involving varying shapes, sizes, and materials.
Authors Publications[1] H. Akutsu, Y. Nagashima, J. Masuda, S. Kohno and Y. Sudo; “ Development an Underground Radar System,” No-Dig Oosaka, 1990,
L4.1-L4.8.
[2] Y. Sudo, Y. Nomura and Y. Nagashima, “A Cavity Signal Recognition Method using Spectrum Pattern Analysis in GPR Received
Wave,” Mechanical Engineering Congress, 2002 Japan, Vol.Ⅶ, pp239-240.
[3] Y. Sudo, Y. Nomura and Y. Nagashima, “Extraction of Cavity Signals from Underground Radar Images Using Frequency Analysis,” The
6th International Conference on Mechatronics Technology, ICMT2002, 2002, pp.129-134

Abstracts of Doctor’s Thesises

117

Preparation and Interface Properties of Highly Purified Polyglycerol
Fatty Acid Esters
Tomoharu Kato*
Key Words: CMC, detergency, foam, interface property, monolayer, polyglycerol ester, polyglycerolmonolaurate, poluglycerol monostearate, surface activity, surface pressure-area isotherm, surfactant property.

Polyglycerol esters of fatty acids (PGE), nonionic surfactants, are widely used in foods, cosmetics,
and other industrial products. The PGE consists of polymerized glycerol units and fatty acids. The
commercial form of PGE is in general a mixture of many different components, which include different glycerol
units from 1 to 10 with various degrees of esterification with fatty acids of different chain lengths. Efforts havebeen made to purify the PGE to characterize the surfactant properties of individual polyglycerol. The
purification process of the mixture was not easy, and hence most studies restricted their discussion on theproperties of the mixture itself. Surfactant properties of a surfactant in aqueous solution are important forcharacterization. It is therefore, necessary to know the surfactant properties of the purified glycerol units.
1.

The purpose
In this study, several PGE were purified and then characterized their surfactant properties in aqueous
solutions.
2. Synthesis of purified polyglycerol esters of fatty acids
Stearic and lauric acid were selected as the fatty acids of PGE. The polyglycerols were purified bysilica gel column to yield the esters, which were composed with fatty acid derivatives. The esterified products
were further purified once again with silica gel column. As a result, highly purified (>95%) di- and triglycerolmonostearates (2GMS and 3GMS), and di- to pentaglycerol monolaurates (2GML, 3GML, 4GML and 5GML)
were obtained. The purity of each polygycerol was checked by gas liquid chromatography. Chain lengths
were confirmed by infrared spectrum, nuclear magnetic resonance spectrum, chemistry ionizing mass spectrum
and atmospheric pressure chemistry ionizing mass spectrum.

π (mN/m)

3. Surface properties of mono-, di-, and triglycerol monostearate monolayers spread at the air/aqueous
solution interface
The monolayer properties of three polyglycerol
60
monostearates spread at the air-water interface were
measured by surface pressure measurement and50
fluorescence microscopy observation as a function of40
glycerol units from 1 to 3. Polyglycerol monostearates
formed stable monolayers at the air/aqueous solution
30
interface and the shape of the surface pressure-area (π-A)
isotherms of the monolayers showed a strong dependence
20
on the glycerol units (Fig.1). Glycerol monostearate(1GMS) showed a typical liquid-condensed (LC) monolayer,
10
2GMS showed a monolayer with a phase transition from0liquid-expanded (LE) to LC states, and 3GMS exhibited LE
2
0
0.5
1
1.5
type monolayer. The collapse surface pressure decreases2
A (nm /molecule)with an increase in the number of glycerol units.
The
fluorescence microscopic images of polyglycerol
Fig.1 Surface pressure -area ( π -A) isotherms of 1GMS
monostearate monolayers are also strongly depended on the(triangles), 2GMS (squares), and 3GMS (circles)monolayers in the abcence (open symbols) and presence
number of glycerol units. When the monolayer of 2GMS
(closed symbols) of NBD-PE at 25 ℃

* Taiyo Kaguku Co.,Ltd.

Abstracts of Doctor’s Thesises

118

is compressed into the LE to LC phase transition, its domain structure changed from circular to radial cusp shape
via horse-bean shape, whereas the domain structure of 1GMS turned from circular to coalesced circular shapewith a decrease in the area.

5.

Conclusion

1) Highly purified 1GMS to 3GMS and 2GML to 5GML were characterized their interface properties.
2) Surface properties of 1GMS to 3GMS monolayers spread at the air/aqueous solution interface strongly
depended on the number of glycerol units.
3) Surfactant properties, such as surface activity, foaming property, interfacial tension, and detergency of thepurified nGML in aqueous solutions strongly depended on the number of glycerol units. Overall, thenGML showed better performance in all the surfactant properties than C12EOn. These results suggest thatnGML having a secondary hydroxyl group on every glycerol unit of the hydrophilic part could be morehydrophilic than C12EOn.
4) PGE could be an abundant source of surfactants because they could be produced from plant sources.
Therefore, nGML could form as the interesting surfactants for the future.
Author’s publications
1.

2.

Masami Kawaguchi, Midori Yamamoto, Takeshi Nakamura, Masatsugu Yamashita, Tomoharu Kato, andTadaya Kato, "Surface Properties of Mono-, Di-, and Triglycerol Monostearate Monolayers Spread at the
Air-Water Interface", Langmuir, 17, 4677-4680 (2001).
Tomoharu Kato, Takeshi Nakamura, Masatsugu Yamashita, Masami Kawaguchi, Tadaya Kato, and Takahito
Itoh, "Surfactant Properties of Purified Polyglycerol Monolaurates", Journal of Surfactant and Detergency,
6, 331-337 (2003).

Removal rate (%)

Surfactant properties of purified polyglycerol monolaurates
Surfactant properties, such as surface
activity, foaming property, interfacial tension, and14
detergencyofthepurifiedpolyglycerol0monolaurates (nGML) in aqueous solutions were
12
systematically examined and were compared with
Interfacial tension
20
the corresponding properties of n-dodecyl
Removal rate10
polyoxyethylene monoethers (C12EOn). The values
40of critical micelle concentration (CMC) and the8surface tension at CMC of nGML and C12EOn were60
6increased linearly with an increase in the number ofglycerol and oxyetylene units, respectively and the480
slope of the increase was greater for nGML than
C12EOn. The minimum surface area per molecule2100
of nGML was smaller than that of C12EOn at the
air/aqueous solution interface. The initial foam
0
1
2
3
4
5
6
7
8
9
heights of the surfactants at the CMC were increased
Number of glycerol or oxyethylene units
with the increase in the number of glycerol or
oxyetylene units and the foam heights of nGML
Fig.2 Plots of interfacial tension of corn oil/surfactant
were always higher and stable than that of C12EOn.
solutions and detergency as a function of the number ofDetergency depended on interfacial tension
glycerol or oxyethylene unites for 2GML (●), 3GML
reduction, 3GML showed the lowest interfacial(■), 4GML (▲), 5GML (◆), C12EO4 (○), C12EO6 (□)
tension and the highest detergency among all theand C12EO8 (△) in aqueous solutions at 30oC
surfactants tested (Fig.2).
Overall, the nGML showed better performance in all the surfactant properties than C12EOn. It is noteworthy
that the surfactant properties of nGML having few glycerol units (di- to tetraglycerol monolaurate) are on parwith that of C12EOn having many oxyetylene units (hexa- and octaoxyethylene). These results suggest thatnGML having a secondary hydroxyl group on every glycerol unit of the hydrophilic part could be morehydrophilic than C12EOn. This characteristic feature guaranteed the superior surfactant properties of nGML.
This study suggests that the purified nGML have excellent surfactant properties relative to their ethoxylated
analogues. nGML are suitable for use as detergents in foods, cosmetics and in other industrial materials.
Interfacial tension (mN/m)

4.

Abstracts of Doctor’s Thesises

119

Studies on the development of technologies for controlling posttranslational modification processes in gene expression system
Masahiro Nagaya(Material Chemistry, Material Science)
Keywords: N-glycosylation, Baculovirus expression system, Antheraea pernyi, lectin blot, 2D-sugar mapping,
posttranslational modification

1. Introduction
Almost all the secreted and membrane-associated proteins of eukaryotic cells are glycosylated. Indeed,
protein glycosylation, especially N-glycosylation, is more abundant than all other types of posttranslational
modifications combined. N-linked glycoproteins are completed in the endoplasmic reticulum and further processed in
the Golgi apparatus. The resulting oligosaccharides are classified into three groups: (1) high-mannose oligosaccharides, (2) complex oligosaccharides, and (3) hybrid oligosaccharides.
These glycoforms are very important,because many studies have been revealing that glycan moieties of the glycoproteins have important roles in various
biological events such as cell adhesion, cell differentiation and proliferation, immune response, neural functions,protein quality control, and so on.
Generally, baculovirus expression vector (BEV) systems possess protein-processing capabilities of insect cells,
which can perform some mammalian-like posttranslational modifications, including glycosylation, and usually show
productivity much higher than mammalian expression systems. Therefore, BEV systems have been frequently
used for production of recombinant mammalian glycoproteins. In general, mammalian cells add complex typeN-glycans often possessing terminal sialic acids, while insect cells add high mannose type or fucosylated
paucimannose type N-glycans. Although variety has been found according to derived insect cell or produced
glycoprotein, the difference in the glycoform between mammalian and insect cells indicates that the BEV systems has
limitations of glycosylation for the production of mammlian-type modified glycoproteins.
Therefore, we attempted to develop a novel technique for controlling posttranslational N-glycosylation
processes in the gene expression systems in insect cells such as AnPe cells.
We studied the structures ofN-linked oligosaccharide added on PTTH in several lepidopteran insect cell lines such as Bombyx mori (BmN4), Spodoptera frugiperda (Sf9), Trichoplusia ni (High5), Spilosoma imparilis (SpIm) and Antheraea pernyi (AnPe) using
lectin blot analysis, identified the structures of N-glycans produced in Sf9 and AnPe using 2D sugar-mapping
technique, and evaluated the potential abilities of the N-glycosylation pathway of AnPe cells to apply for the mammalian-type posttranslational N-glycosylation process.
2. The structural investigation of N-glycan produced in five lepidopteran insect cell lines using lectin blot analysis
Recombinant PTTH produced and secreted by each cell line showed the significant variation in apparent
molecular mass ranging between 13 and 20 kDa. Differences in N-glycan structure and/or proteolytic processing
were considered as major reasons. In fact, lectin blot analysis revealed that lectins GNA and AAA, which are
specific to terminal α-linked mannose and α1,6-linked fucose respectively, clearly bound to recombinant PTTH
produced by each cell line, while lectins RCA120, MAA and SNA, which are specific to β1,4-linked galactose,
α2,3-linked sialic acid and α2,6-linked sialic acid respectively, did not bind to each PTTH sample. The results
indicated that the majority of recombinant PTTH produced by AnPe as well as other lepidopteran cell lines carriedfucosylated paucimannosidic N-glycans as generally observed in recombinant glycoproteins produced by BEV
systems. In this study, all the results did not support the preliminary result indicating that AnPe added complex
type N-glycans to the recombinant glycoprotein. However, it may be probable that amounts of complex typeN-glycan added on PTTH were below detectable limits of lectin blot analysis. In addition, there is a possibility that
PTTHs with sialylated N-glycan were removed during the preparation of crude PTTH samples by ion exchange

120

Abstracts of Doctor’s Thesises

column chromatography, which was used for separation of charged N-glycans containing sialic acid from uncharged
N-glycans. Therefore, we cannot conclude the inability of AnPe as well as other cell lines to form complex typeN-glycan. Further analysis of N-glycan structure on affinity-purified recombinant PTTH in conjunction withbiochemical and molecular biological analyses of the cell lines to identify glycosyltransferases and the responsible
genes required for complex type N-glycan formation will provide us reliable answers.
3. The characterization and determination of N-glycans derived from baculovirus-infected AnPe and Sf9 insect celllines using 2D sugar- mapping technique
To evaluate the N-glycosylation property of an insect cell line, Antheraea pernyi (AnPe), and used in a newly
developed baculovirus expression vector system, N-glycans of purified PTTH produced by AnPe cells infected with arecombinant A. pernyi nucleopolyhedrovirus (AnpeNPV), were digested with glycoamidase A (from sweet almond),
reductively aminated with 2-aminopyridine, and identified by two-dimensional high performance liquid
chromatography (2D-HPLC) mapping technique. For comparison, N-glycans of PTTH produced by Spodoptera
frugiperda cells (Sf9) infected with a recombinant Autographa californica NPV (AcNPV) were also analyzed
similarly.
Consequently, similarities and differences in the N-glycan structure composition between AnPe and Sf9
were revealed. N-glycans from AnPe contained 41.8% high mannose type, 32.8% paucimannosidic type, 12.5%
monoantennary type, and 1.3% biantennary, complex type with terminal N-acetylglucosamine (GlcNAc) residues(Fig. 1a), while those from Sf9 contained 46.5% high mannose type, 29.8% paucimannosidic type, 7.7%
monoantennary type, and no detectable biantennary complex type. In addition, one of the monoantennry typeN-glycans with a terminal GlcNAc residue identified in AnPe was not detected in Sf9 (Fig. 1b). The proportion of
N-glycans with an α-1,6-linked fucose residue at the innermost core GlcNAc residue was 41.4% in AnPe and 23.4%
in Sf9, respectively. In both cell lines, mammalian-like complex N-glycans with terminal galactose and/or sialic
acid residues were not identified. These results indicated that a reaction catalyzed by GlcNAc transferase II(GnTII), a key enzyme to form biantennary, complex N-glycans, occurs more efficiently in AnPe than in Sf9,
suggesting that the proportion of complex N-glycans in AnPe cells may be largely enhanced by inhibiting theN-acetylglucosaminidase activity and/or supplying sufficient amounts of enzymes and substrates required for thesugar chain extension in the Golgi.

(a)

(b)

Fig.1 Unique structure on the recombinant PTTH produced by AnPe cells.
4. Conclusion remarks
Overall, the present study demonstrated that, although the AnPe cells possess typical N-glycosylation
properties common in insect cells, they also possess an ability to add the complex N-linked oligosaccharides, but not
the galacotose and sialic acid residues, suggesting that AnPe cells are suitable for production of mammalian-like
glycoproteins, although the improvement to produce authentic glycoproteins is required. BEVsystem in AnPe cells
must be widely used as a large-scale production system for therapeutic glycoproteins and as a system to elucidate afunctional mechanism of oligosaccharide moieties of glycoproteins.
Author’s publications[1] Masahiro Nagaya, Jun Kobayashi and Tetsuro Yoshimura. Evaluation of N-glycosylation Property of Cultured
Antheraea pernyi Cells in Comparison with Four Other Lepidopteran Cell Lines used in Baculovirus Vector Systems. Int.J. Wild Silkmoth & Silk. (2002) 7, 59-68.
[2] Masahiro Nagaya, Jun Kobayashi, Noriko Takahashi, Koichi Kato and Tetsuro Yoshimura. Two-dimensional
High Performance Liquid Chromatography Mapping of Sugar Chains Demonstrated the Biantennary, Complex
N-Glycan Addition to the Recombinant Glycoprotein Produced by Baculovirus-Infected Antheraea pernyi Insect Cells. J. Insect Biotechnology & Sericology. (2003) 72, 79-86.