bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of EuCrO4 and Its Electronic and Magnetic Properties
Authors: Konno Hidetaka , Aoki Yoshitaka , Klencsár Zoltán , Vértes Attila , Wakeshima Makoto , Tezuka Keitaro , Hinatsu Yukio
Published: December 2002

Single phase zircon type EuCrO4 (S.G. I41/amd) was synthesized and the structure including atomic positions was precisely determined by X-ray Rietveld refinement. The electronic and magnetic properties of the compound were studied based on the electric conductivity, Seebeck coefficient, Raman spectroscopy, Mössbauer spectroscopy, magnetic susceptibility, and specific heat. The CrO43− tetrahedra in EuCrO4 were slightly elongated compared with that in NdCrO4, which caused splitting of the degenerated vibration modes of CrO43−, ν2 and ν3, in the Raman spectra. The 151Eu Mössbauer spectra showed not a trace of the Eu(II) species in the compounds measured in the present work. The Debye temperature, ΘD, estimated from Mössbauer spectra suggested that the vibrational state of Eu(III) in EuCrO4 was similar to that in the perovskite-type EuCrO3. However, the isomer shift of Mössbauer spectra revealed that the electron density of the 6s orbital of Eu(III) in EuCrO4 was very low and almost the same as that in the zircon type EuVO4, that is, Eu(III) in these compounds has highly ionic character, whereas the electron density of the 6s orbital of Eu(III) in EuCrO3 was higher and nearly the same as that in Eu2O3. EuCrO4 was found to be an n-type semiconductor similar to NdCrO4, while zircon type REMO4 (RE: rare earth metal(III); M: V, P, As, etc.) are insulators. Magnetic susceptibility and specific heat measurements showed that antiferromagnetic transitions took place at around 15 K and was solely due to Cr(V) from the magnetic entropy value of 5.54 J mol−1 K−1.
Chloride Transfer across the Liquid–Liquid Interface Facilitated by a Mono-Thiourea as a Hydrogen-Bonding Ionophore
Authors: Nishizawa Seiichi , Yokobori Tomoyuki , Kato Ryo , Shioya Takeshi , Teramae Norio
Published: December 2002

Applicability of a thiourea-based hydrogen-bonding ionophore 2, N,N′-bis(p-nitrophenyl)thiourea, for amperometric anion sensors is presented. Chloride transfer across the nitrobenzene (NB)–water interface facilitated by this ionophore is studied by using ion transfer polarography. When 2 is present in the organic phase, a well-defined wave can be observed, indicating that the chloride transfer across the NB–water interface is facilitated by 2 via formation of hydrogen bonds. The analysis of ion transfer polarograms shows that the chloride transfer is assisted by 1 : 1 complexation between 2 and chloride, and that the transfer process is reversible and controlled by diffusion of 2 from the bulk NB phase to the interface. Despite its simple binding mode based on two point interactions, mono-thiourea 2 has a strong ability to facilitate chloride transfer, which is comparable to that obtained for a highly preorganized bis-thiourea ionophore 1, 2,7-di-t-butyl-4,5-bis(N′-butylthioureylene)-9,9-dimethylxanthene, in which four hydrogen bonds are involved in the chloride binding.
Pressure-Stabilized Low-Spin State for Binuclear Iron(III) Spin-Crossover Compounds
Authors: Hayami Shinya , Hosokoshi Yuko , Inoue Katsuya , Einaga Yasuaki , Sato Osamu , Maeda Yonezo
Published: December 2002

Binuclear iron(III) spin-crossover complexes with salten ligand [Fe2(salten)2(L)](BPh4)2 were synthesized and characterized by single-crystal X-ray diffraction, Mössbauer spectra, magnetic susceptibilities and electronic spectra, where H2salten is a pentadentate ligand derived from salicylaldehyde and 3,3′-diaminodipropylamine and L is a didentate axial ligand (az = azobis(4-pyridine) and cc = 4,4′-vinylenebis(pyridine)). The structures of [Fe2(salten)2(az)](BPh4)2 (1) and [Fe2(salten)2(cc)](BPh4)2 (2) were determined at both 100 K and 298 K. Crystal data for 1 at 100 K: C98H94O4N10B2Fe2, monoclinic, space group P21/c, Z = 2, a = 15.986(2) Å, b = 15.825(2) Å, c = 16.441(2) Å, β = 107.902(2)°, V = 3957.8(8) Å3. Crystal data for 2 at 100 K: C100H96O4N8B2Fe2, monoclinic, space group P21/a, Z = 2, a = 16.4296(8) Å, b = 15.747(1) Å, c = 16.637(1) Å, β = 109.2375(9)° and Z = 2. The complexes 1 and 2 exhibited the spin-crossover behavior depending on temperature within the temperature range of 200 to 350 K, and rapid spin equilibrium behavior was observed by means of Mössbauer spectroscopy at 293 K. The complexes 1 and 2 also exhibited a pressure-induced spin transition between the rapid spin equilibrium state and low-spin state at 300 K. Such a pressure-induced spin transition has not been reported earlier.
Spectrophotometric Determination of Chromium in Ores, Steels and Pure Nickel Samples using Phenothiazines
Authors: Mohamed Ashraf Abdel-Aaty
Published: December 2002

A new, simple, and sensitive method has been developed for the spectrophotometric determination of CrVI based on its reaction with chlorpromazine-HCl (CPH) to give a red product. Under the optimum conditions, the linear range of the calibration graph was 0.00–0.33 µg mL−1 of CrVI. The molar absorptivity and the detection limit were 3.28 × 104 dm3 mol−1 cm−1 and 0.003 µg mL−1 of CrVI, respectively. Analyses of certified ores, steels, and pure nickel samples gave results in excellent agreement with the nominal values and with relative standard deviations of ≤ 1.5%
Neutral Lithium Triflate (LiOTf) Efficiently Catalyzes Chemoselective Preparations of Cyclic and Acyclic Dithioacetals from Carbonyl Compounds, Acylals, and O,O-Cyclic and Open-Chain Acetals under Solvent-Free Conditions
Authors: Firouzabadi Habib , Eslami Shahram , Karimi Babak
Published: December 2002

An efficient and chemoselective preparation of cyclic and acyclic thioacetals from carbonyl compounds, cyclic and acyclic acetals and acylals in the presence of catalytic amounts of neutral lithium triflate and thiols under solvent-free conditions is described.
Hydrogen-Bond-Like Nature of the CH/π Interaction as Evidenced by Crystallographic Database Analyses and Ab Initio Molecular Orbital Calculations
Authors: Takahashi Osamu , Kohno Yuji , Iwasaki Sachiyo , Saito Ko , Iwaoka Michio , Tomoda Shuji , Umezawa Yoji , Tsuboyama Sei , Nishio Motohiro
Published: December 2002

Spatial distribution of CH hydrogen atoms with reference to a six-membered carbon aromatic ring was analyzed in the crystal structures deposited in the Cambridge Structural Database (CSD). The crystal data showed the propensity that the CH hydrogen atoms lie above the center of the aromatic ring to form interatomic CH/π contacts. Investigation of the effects of the CH proton acidity on the strength and the structure of the CH/π interaction has demonstrated that the distance between the hydrogen atom and the π plane (Dpln) decreases with increase of the CH proton acidity (Dpln: CCH3 ≅ sp2-CH > sp-CH ≅ Cl2CH2 > Cl3CH), and that the C–H···π access angle (α) tends to approach 180° in the same order. Further, a negative correlation has been found between Dpln and α. The directional preferences are in accord with the property of conventional hydrogen bond, indicating a hydrogen-bond-like character of the CH/π interaction. In order to elucidate the intrinsic nature of the CH/π interaction, ab initio calculations [MP2/6-311++G(d,p)] were carried out for methane/benzene, ethylene/benzene, and acetylene/benzene complexes. Potential surfaces obtained for the three model supramolecules are consistent with the results from the CSD analyses.
Site-Selective Deposition of Enzyme/Polyelectrolyte Multilayer Films on ITO Electrodes Controlled Electric Fields
Authors: Shi Lixin , Sun Junqi , Liu Junqiu , Shen Jiacong , Gao Mingyuan
Published: December 2002

Electric field directed layer-by-layer assembly (EFDLA) approach was for the first time employed to realize site-selective deposition of enzyme/polyelectrolyte films on two independent indium-tin-oxide electrodes. Enzyme activities and thickness of the resulted films were investigated and compared with those of normal layer-by-layer self-assembled films of enzyme. All results prove that the site-selective deposition was successfully realized at applied voltage of 1.2 V.
A Simple In Situ Hydrogen Bond Interaction to Homogeneous Dispersion of Gold Nanoparticles in SiO2 Matrix Using Dendrimer as Template
Authors: Zhou Yong , Ma Chenghuan , Itoh Hideaki , Naka Kensuke , Chujo Yoshiki
Published: December 2002

A novel dendrimer-templated gold nanoparticle was homogeneously dispersed in SiO2 matrix via in situ hydrogen bond interaction between the dendrimer and silica matrix.
Fabrication of Three-component Micropatterned Organosilane Monolayer by a Stepwise Photolithography Process
Authors: Koga Tomoyuki , Otsuka Hideyuki , Takahara Atsushi
Published: December 2002

Three-component micropatterned organosilane monolayer was successfully fabricated on Si-wafer substrate by a stepwise photolithography process. Scanning force microscopic observations revealed that three kinds of organosilane monolayers with different physicochemical properties were area-selectively immobilized on a Si wafer.
UV Light Driven Morphological Changes in Lamella Films of a Poly(ethylene imine) Complex with 4-Dodecyloxycinnamic Acid
Authors: Ohtani Osamu , Takagi Katsuhiko
Published: December 2002

A cast multilayer film of poly (ethylene imine) (PEI) complex involving 4-dodecyloxycinnamic acid (C12OCin) was found to show layer shrinkage along the c-axis on the glass plate under UV illumination at λ>300 nm. The bilayer units in the stacked lamella film successively shifted from 4.7 to 4.2 nm in length, induced by the E-to-Z photoisomerization, indicating continuous changes in the layer distances. This shrinkage behavior shows a contrast to that observed in the case of an ion-pair film of dioctadecyldimethylammonium cinnamate (DDAC) which exhibits no intermediate layer distance during a similar photoinduced shrinkage of the film.
The Synthesis of Two Types of Layered Niobate Hybrid Materials by the Selective Intercalation of Ionic Porphyrin
Authors: Tong Zhiwei , Shichi Tetsuya , Kasuga Yoshiyuki , Takagi Katsuhiko
Published: December 2002

K4Nb6O17 is a layered semiconductor possessing two different layer structures, i.e., interlayers I and II. The present paper reports on the selective synthesis of two types of layered niobate hybrid materials by the introduction of 5,10,15,20-tetrakis(1-methyl-4-pyridinium)-21H,23H-porphyrin (TMPyP4+) into either interlayer I or into both I and II by a guest-guest exchange method using the intercalation compounds (MV2+)xK4−2xNb6O17 and (PrNH3+)xH4−xNb6O17 as precursors.
Separation of Americium(III) from Lanthanide by Encapsulating Hexadentate-ligand
Authors: Watanabe Masayuki , Mirvaliev Rinat , Tachimori Shoichi , Takeshita Kenji , Nakano Yoshio , Morikawa Koshi , Mori Ryohei
Published: December 2002

Am(III) is encapsulated in an aqueous phase by a podand-type ligand, N,N,N′,N′-tetrakis(2-methylpyridyl)ethylenediamine (TPEN), and is extracted selectively over trivalent lanthanide in an organic phase using nitrobenzene. The extraction of Am(III) using TPEN shows higher selectivity and chemical stability than other conventional ones using nitrogen-donor ligands.
Fast Preparation of Nano-sized Nickel Particles under Microwave Irradiation without Using Catalyst for Nucleation
Authors: Tsuji Masaharu , Hashimoto Masayuki , Tsuji Takeshi
Published: December 2002

Nano-sized nickel particles have been prepared through reduction of Ni(OH)2 with ethylene glycol under microwave irradiation. Without using such a catalyst as Pt for nucleation, spherical nickel particles with a diameter of 6±3 nm were produced within 5 min.
[{(H2O)Ni(enMe)2MoV4MoVI4VIV8(VVO4)O40}2{Ni(enMe)2}][Ni(enMe)2]4·8H2O: The First Dimer of Polyoxometalates Linked through Coordination Fragment
Authors: Cui Xiao-Bing , Yang Guo-Yu
Published: December 2002

The hydrothermal reaction of V2O5, MoO3, NiCl2·6H2O, enMe (1,2-diaminopropane) and H2O produces [{(H2O)Ni(enMe)2MoV4MoVI4VIV8(VVO4)O40}2{Ni(enMe)2}][Ni(enMe)2]4·8H2O, which is the first compound containing polyanion dimer linked by transition metal coordination fragment. The structure of this compound was determined by single crystal X-ray diffraction, EPR and IR analysis.
All Solid-state Lithium Secondary Batteries Using High Lithium Ion Conducting Li2S–P2S5 Glass-Ceramics
Authors: Mizuno Fuminori , Hama Shigenori , Hayashi Akitoshi , Tadanaga Kiyoharu , Minami Tsutomu , Tatsumisago Masahiro
Published: December 2002

All solid-state cells of In/LiCoO2 using the 80Li2S·20P2S5 (mol%) glass-ceramics with high ambient temperature conductivity of about 10−3 S cm−1 as a solid electrolyte were fabricated, and the cell performance was investigated. Although an irreversible capacity was observed at the 1st cycle, the solid-state cell exhibited excellent cycling performances with the reversible charge-discharge capacities of about 100 mAh g−1 even after 200 cycles.
Stereocontrolled Syntheses of Carotenoid Oxidative Metabolites, (−)-Loliolide, (−)-Xanthoxin, and Their Stereoisomers
Authors: Kuba Masako , Furuichi Noriyuki , Katsumura Shigeo
Published: December 2002

We achieved the stereocontrolled syntheses of (−)-loliolide, (−)-xanthoxin, and their stereoisomers from (+)- or (−)-3-alkoxy-6-hydroxymethyl-1,1,5-trimethylcyclohexene through the corresponding syn and anti-epoxides, respectively, which were obtained by utilizing the highly diastereoselective Sharpless asymmetric epoxidation or mCPBA oxidation.
Efficient Nonsintering Type Dye-sensitized Photocells Based on Electrophoretically Deposited TiO2 Layers
Authors: Miyasaka Tsutomu , Kijitori Yujiro , Murakami Takurou N , Kimura Mitsuhiro , Uegusa Sadao
Published: December 2002

A non-sintering method for preparing nanoporous semiconductor layers for dye-sensitized photocells was developed in which TiO2 particles were electrophoretically deposited on an electrode and post-treated by chemical vapor deposition of Ti alkoxide and microwave irradiation. The method provides photocells with energy conversion efficiency up to 4.1% under irradiation of AM1.5 light (100 mW/cm2).
Stereoselectivity in Intramolecular Cyclization of Non-conjugated Unsaturated Ketones by Electroreduction
Authors: Nishiguchi Ikuzo , Goda Satoshi , Yamada Kouji , Yamamoto Yoshimasa , Maekawa Hirofumi
Published: December 2002

This study showed some decrease in stereoselectivity in electroreductive intramolecular cyclization of nitrogen-containing non-conjugated enones in comparison with high stereoselectivity for the corresponding enones possessing an all-carbon-chain or a sulfur-containing chain. This phenomenon may provide some actual experimental supports for the remarkable stereochemical features of the electroreductive cyclization.
Graded EB‐PVD‐Thermal Barrier Coatings Produced by Powder Evaporation
Authors: Lugscheider E. , Bobzin K. , Etzkorn A. , Syrakas G. , Siry C.W.
Published: December 2002

Gas turbines in aircraft operation are very often equipped with EB‐PVD coated first stage blades. EB‐PVD coatings provide a thermal barrier between the hot gas stream and the cooled metal part of the blade. To enhance the erosion resistant behavior of the TBC, in this work a graded transition from zirconia as TBC to alumina as erosion protective coating was investigated.
Titelbild: Angew. Chem. 24/2002
Authors: Marlin Dana S. , Bill Eckhard , Weyhermüller Thomas , Rentschler Eva , Wieghardt Karl
Published: December 2002

Das Titelbild zeigt die Struktur eines paramagnetischen Dimangankomplexes, der an ein entferntes organisches Radikal gebunden ist. Die weit reichenden magnetischen Wechselwirkungen zwischen den beiden Zentren mit S=1/2 in diesem Komplex können als Modell einer ähnlichen Situation, die im S2Yz.‐Zustand des Photosystems II (PSII) vorliegt, betrachtet werden. In ihrer Zuschrift auf Seite 4969 ff. erhellen D. S. Marlin, E. Bill und K. Wieghardt et al. die Natur dieser Wechselwirkung durch Verwendung von SQUID‐Messungen und Zweikanal‐X‐Band‐EPR‐Spektroskopie. Eine der bemerkenswertesten Beobachtungen in solchen Zweikanal‐EPR‐Messungen ist die Identifizierung von gut aufgelösten „verbotenen“ Halbfeld‐Multilinien‐Signalen bei g=4, die von dipolaren Kopplungen herrühren. Letzteres könnte im Zusammenhang mit einem wenig verstandenen Signal bei g=4.1, das in verschiedenen EPR‐Spektren des PSII auftritt, von Bedeutung sein.
Curing and thermal behavior of epoxy resin in the presence of silicon‐containing amide amines
Authors: Khurana Parveen , Aggarwal S , Narula A. K. , Choudhary Veena
Published: December 2002

The article describes the synthesis and characterization of silicon‐containing amide amines obtained by the reaction of bis(4‐chlorobenzoyl)dimethylsilane with 4,4′‐diaminodiphenyl ether, 4,4′‐diaminodiphenyl methane, 4,4′‐diaminodiphenyl sulfone/3,3′‐diaminodiphenyl sulfone, bis(3‐aminophenyl)methyl phosphine oxide, and tris(3‐aminophenyl)phosphine oxide with dimethyl acetamide as a solvent. Structural characterization of amide amines was done with Fourier transform infrared and 1H‐NMR spectroscopy. We used these aromatic amide amines as curing agents to investigate the effect of structure and molecular size on the curing and thermal behavior of diglycidyl ether of bisphenol A (DGEBA). The curing behavior of DGEBA in the presence of stoichiometric amounts of silicon‐containing aromatic amide amines was investigated by differential canning calorimetry. A broad exothermic transition in the temperature range of 200–300°C was observed in all the samples. The peak exotherm temperature was lowest in the case of phosphorus‐containing amides and was highest in the case of ether‐containing amides. Thermal stability of the isothermally cured resins was evaluated with dynamic thermogravimetry in a nitrogen atmosphere. A significant improvement in the char yield was observed with silicon‐containing amines, and it was highest in case of samples with both silicon and phosphorus as flame‐retarding elements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1345–1353, 2003
Natural weathering of polypropylene in a tropical zone
Authors: Bedia Elinor L. , Paglicawan Marissa A. , Bernas Cynthia V. , Bernardo Severino T. , Tosaka Masatoshi , Kohjiya Shinzo
Published: December 2002

Natural weathering of isotactic polypropylene (PP) plates (2 mm in thickness) was conducted for 15 months in the Philippines. Optical microscopy, scanning electron microscopy, and atomic force microscopy revealed that the surface layer (200–300 nm in thickness) was affected in the first month, and cracks are formed toward the deeper layer. On the basis of the microscopic observations along with FTIR, DSC, GPC, and tensile strength measurements, the following degradation mechanism of PP was proposed. At first, through oxygen introduced into the PP, only the surface layer seems to be affected. Gradually, the surface layer may be removed, exposing the inner layer. Then, molecular chains of the inner layer start to be degraded, accompanying a significant loss of tensile properties. Part of the degraded materials seems to be eroded, leading to the formation of cracks on the surface of the uncovered inner layer. Finally, the original surface layer may be totally eroded, making the structure of the inner layer (which should reflect the spherulitic texture) evident. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 931–938, 2003
Conducting properties of iodine‐doped low‐density polyethylene–poly(4‐vinylpyridine) blends
Authors: da Silva Sidnei Luis Andrade , Temperini Marcia Laudelina Arruda , Gomes De Barros Glaucione
Published: December 2002

The conductivities of blends of low‐density polyethylene and poly(4‐vinyl pyridine) (P4VP) were studied. The blends were synthesized by in situ sorption and thermal polymerization of 4‐vinylpyridine in low‐density polyethylene. They showed, after iodine doping, conductivities of 1.7 to 5.0 × 10−7 S cm−1 at 298 K, depending on the P4VP mass increment into the matrix. Their conductivities were one order of magnitude higher for measurements at 338 K. The optimum ratio of iodine to pyridine (n) which gave the highest conductivity was 0.21. The thermal stability of doped blends was acceptable for their uses as electrochemical devices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 939–944, 2003
Synthesis and properties of polyimides containing bisphenol unit and flexible ether linkages
Authors: Leu Tsu‐Shang , Wang Chun‐Shan
Published: December 2002

A series of novel polyimides was prepared from various diamines (with bisphenol units) and various aromatic tetracarboxylic dianhydrides via a two‐step (thermal imidization) method. The monomers and polymers were produced in high yields. The benzophenone series exhibited better solubility than the pyromellitic series and, especially, those with the alkyl (methyl)‐substituted ring exhibited good solubility and could be readily dissolved in polar aprotic solvents such as dimethylformamide and N,N′dimethylacetamide. The glass transition temperatures of all polyimides were found to be 235–322 and 223–332°C, respectively, by DSC and dynamic mechanical analysis. Thermogravimetric analyses indicated that the polymers were fairly stable up to 482–617°C (10 wt % loss in N2) and 480–610°C (10 wt % loss in air). Wide‐angle X‐ray diffractograms revealed that most polyimides were predominantly amorphous. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 945–952, 2003
Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology, morphology, and mechanical properties
Authors: Huang Jieh‐Ming , Ju Ming‐Yih , Hung Chen‐Jui , Luoh Wen‐Chin , Chang Feng‐Chih
Published: December 2002

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003
Miscibility and crystallization of metallocene polyethylene blends with polypropylene
Authors: Li Jun , Shanks Robert A. , Long Yu
Published: December 2002

The crystallization and morphology of very‐low‐density polyethylene (VLDPE) and ultra‐low‐density polyethylene (ULDPE) blends with isotactic polypropylene (PP) were studied by differential scanning calorimetry (DSC) and hot‐stage optical microscopy (HSOM) with polarized light. In particular, the isothermal crystallization of PP in molten PE was investigated. A polypropylene homopolymer was melt‐blended with six types of VLDPEs and ULDPEs, with variations in branch content and length and in molecular weight. All the blends contained 20% PP by mass. It was found that the crystallization temperatures of PP and PE changed in the blends, and the crystallization of PP was affected by branch length and content and by the molecular weight of the PE, indicating a certain degree of miscibility between PP and PE. The isothermal crystallization rate of PP decreased in the blends; in particular, the crystallization rate of PP was slower in the ULDPE with lower MFI, suggesting that crystallization of PP was hindered by PE and that its rate was regulated by the viscosity of ULDPE. HSOM images showed that a portion of the PP crystallized from molten PE, although phase separation was obvious, providing additional information on the miscible behavior between PP and VLDPEs (or ULDPEs). Furthermore, the miscible level between the PP and the ULDPEs was higher than that between the PP and the VLDPEs because the degree of change in the crystallization behavior of the PP and PE was greater in the PP–ULDPE blends. This was possibly a result of the higher branch content in the ULDPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1179–1189, 2003
Oxygen enrichment across blend membranes of bipyridine and ethyl cellulose
Authors: Huang Mei‐Rong , Xu Qian‐Wei , Gu Shu‐Ying , Wu Yan‐Hui , Dong Zhi‐Qing , Wang Jian , Shao Hong‐Tao , Wang Xue‐Song
Published: December 2002

Blend membranes of 2,2′‐bipyridine (2BP) or 4,4′‐bipyridine (4BP) with ethyl cellulose (EC) containing no more than 25 wt % BP are prepared and evaluated for their oxygen enrichment by both the constant pressure–variable volume method and the constant volume–variable pressure method. The actual air‐separation ability through the 2BP/EC blend membrane containing 1.5–7 wt % 2BP are enhanced while the permeated flux is slightly increased in comparison with the virgin EC membrane. Among the 2BP/EC blend membranes examined, the 2BP/EC blend membrane containing 3 wt % 2BP offers the best oxygen/nitrogen permselectivity and yields the highest oxygen concentration of 42.7% at the transmembrane pressure difference of 0.75 MPa and 25°C. Like other homogeneous dense membranes, the BP/EC blend membrane demonstrates strong dependencies on the transmembrane pressure difference, retentate/permeate flux ratio, and operating temperature. It possesses higher activation energy of oxygen and nitrogen permeation than those of the virgin EC membrane in the tested temperature range of 9.7–60°C. The CO2 over CH4 permselectivity through EC membranes can be improved by introducing 4BP, and the ideal oxygen over nitrogen separation factor through the 4BP/EC (10/90) membrane increases 16% at the upstream pressure of 10 bar compared with the virgin EC membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1371–1381, 2003
Novel degradable polyphosphazene hydrogel beads for drug controlled release
Authors: Qiu Liyan
Published: December 2002

Novel water‐soluble polyphosphazene containing carboxylatophenamino groups (PCPAP) was synthesized by the substitution reaction of ethyl p‐amino benzonate with poly(dichlorophosphazene), followed by alkali hydrolysis. Characterizations by IR, 1H‐NMR, differential scanning calorimetry, and elemental analysis indicated that the reaction brought about an almost complete introduction of carboxylatophenamino to the polymer side chain. Calcium‐crosslinked PCPAP hydrogel beads were accomplished with an extremely mild method. The erosion experiments were conducted in vitro in various pH environments. The erosion duration of the beads at pH 7.4 and 37°C was effectively extended by an increase in the concentration of the PCPAP or CaCl2 solution during the preparation process. Moreover, the bead erosion was sensitive to the pH. The sample dissolved 39.4% in a pH 8.0 buffer within 34 days but only 5.3% in a pH 5.0 buffer. Furthermore, PCPAP underwent degradation into macromolecular segments through the breaking of the backbone, and this could prevent accumulation in the body. These properties of PCPAP may be useful for controlled drug delivery, including intestine‐specific oral delivery systems. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 986–992, 2003
Thermoplastic polymers as modifiers for urea‐formaldehyde (UF) wood adhesives. I. Procedures for the preparation and characterization of thermoplastic‐modified UF suspensions
Authors: Rachtanapun P. , Heiden P.
Published: December 2002

Acrylic thermoplastic copolymers with different degrees of hydrophilicity were prepared and introduced into a commercial aqueous urea‐formaldehyde (UF) suspension at 5–10% w/v. The most hydrophilic acrylic thermoplastic was introduced into the UF suspension as an aqueous solution, whereas the most hydrophobic acrylic was introduced as a surfactant‐stabilized suspension. Acrylics with intermediate hydrophilicity were introduced into the UF suspension as a self‐dispersed aqueous suspension. The thermoplastic‐modified UF suspensions with 5% thermoplastic (58% solids) had a viscosity at 30°C of ∼ 114 cP, compared with a viscosity of ∼112 cP for the original UF suspension (60% UF solids). At 10% thermoplastic (63% solids), all the thermoplastic‐modified UF suspensions exceeded 200 cP. The viscosity of the UF suspension modified with self‐dispersed thermoplastic was reduced by ∼ 50% by reducing the thermoplastic molecular weight. SEM micrographs of cured thermoplastic‐modified UF showed phase‐separated thermoplastic domains in a continuous UF phase for the UF modified with self‐dispersed and surfactant‐stabilized thermoplastic, but UF modified with the water‐soluble thermoplastic showed a single phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 890–897, 2003
Inhibition of radical polymerization in solvent‐based systems (security of solvent‐based radical polymerization of PSA‐acrylic in a plant reactor)
Authors: Czech Zbigniew
Published: December 2002

This article shows the influence of some chain‐transfer agents as inhibitors for acrylic solvent‐based polymerization. These chain‐transfer agents can offer significant advantages, as outlined below. The following chain‐transfer agents were studied to stop or slow down the polymerization process in the case of a runaway: n‐dodecyl mercaptan, trimethylolpropane‐trimercaptoacetate, phenothiazine, diphenylphenylen diamine, cuprum oxide, isopropanol, toluene, and carbon tetrachloride. Synthesized pressure‐sensitive adhesive based on acrylic polymers and containing 2‐ethylhexyl acrylate, methyl acrylate, and acrylic acid were used for the production of self‐adhesives with high cohesion. The polymerization was accomplished in ethyl acetate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1354–1357, 2003
Effect of various added compatibilizers on the crystalline structure of polypropylene homopolymer/polybutylene terephthalate and polypropylene copolymer/polybutylene terephthalate polymer blends
Authors: Vashi P. N. , Kulshreshtha A. K. , Dhake K. P.
Published: December 2002

Blends of semicrystalline isotactic polypropylene homopolymer and polypropylene copolymer with polybutylene terephthalate with different compatibilizers [i.e., styrene acrylonitrile, Surlyn, styrene–ethylene–butadiene styrene (SEBS), block copolymer and SEBS block copolymer grafted with maleic anhydride] were prepared by melt blending. Wide angle‐X‐ray scattering patterns of injection moldings were obtained. The crystallinity index and d‐spacing were calculated with different concentrations of different compatibilizers. X‐ray results in the structural investigation of the compatibilized blends correlated well with the different compatibilizer concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1190–1193, 2003
Viscometric studies of poly(N‐vinyl‐2‐pyrrolidone) in water and in water and 0.01% bovine serum albumin at 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K
Authors: Singh Man , Kumar Sanjay
Published: December 2002

Viscosity and density studies for 0.01–0.14% (w/w) poly(N‐vinyl‐2‐pyrrolidone) (PVP) in water and in water and 0.01% bovine serum albumin (BSA) were conducted at 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, and 313.15 K. The viscosity coefficients and the activation‐energy, free‐energy, enthalpy, and entropy changes were calculated from viscosity data for viscous flow. On this basis, PVP–PVP, PVP–BSA, PVP–water, and BSA–water interactions and PVP and BSA shape factors were investigated and rationalized in terms of the water structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1001–1015, 2003
Nonisothermal crystallization behavior of poly (butylene terephthalate)–poly (ethylene terephthalate‐co‐isophthalate‐co‐sebacate) segmented copolyesters
Authors: Zhao Yun Hui , Sheng Jing , Wang Ya Quan
Published: December 2002

In this paper, two different analytical methods were applied to investigate nonisothermal crystallization behavior of copolyesters prepared by melting transesterification processing from bulk polyesters involving poly (butylene terephthalate) (PBT) and ternary amorphous random copolyester poly(ethylene terephthalate‐co‐isophthalate‐co‐sebacate) (PETIS). The results show that the half‐time of crystallization of copolyesters depended on the reaction time and decreased with the content of ternary polyesters in the amorphous segment. The modified Avrami model describes the nonisothermal crystallization kinetics very well. The values of the Avrami exponent range from 2.2503 to 3.7632, and the crystallization kinetics constant ranges from 0.0690 to 0.9358, presenting a mechanism of three‐dimensional spherulitic growth with heterogeneous nucleation. Ozawa analysis, however, failed to describe the nonisothermal crystallization behavior of copolyesters, especially at higher cooling rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1232–1238, 2003
Synthesis and characterization of poly(N‐isopropylacrylamide)s initiated with siloxane oligomer–(NH4)2Ce(NO3)6 redox pair
Authors: Erbil Candan , Akın Hatice , Uyanık Nurseli
Published: December 2002

Poly(N‐isopropylacrylamide)s (PNIPAAM)s were synthesized via free‐radical polymerization using a ceric ammonium nitrate, Ce(IV)–α‐ω‐dihydroxy(polydimethylsiloxane) (Tegomer H‐Si 2111, PDMS) redox pair in hexane at 30°C in a nitrogen atmosphere. The dependence of the initiation and termination steps on the [NIPAAM]/[Ce(IV)] and [NIPAAM]/[PDMS] ratios were studied using gravimetry and FTIR, 1H‐NMR, UV‐vis, and GFAA spectroscopy techniques. Gravimetric results indicated that, in the case of high concentrations of PDMS, the percentage of the solid portions of the products decreased while the amount of the oligomeric NIPAAM chains increased, that is, as the amount of PDMS in hexane was increased, the number of the short NIPAAM chains having PDMS segments at the two ends, also increased. UV‐vis results showed that the LCST of PNIPAAM initiated with Ce(IV) alone was higher than those of the ones that were synthesized using common initiator systems such as an ammonium persulfate–N,N,N′,N′‐tetramethylethylenediamine redox pair and azobis(isobutyronitrile). Further, it was observed that both siloxane blocks and NH groups forming coordination bonds with free Ce(IV) ions and/or metal–ligand complexes had an important effect on the aggregation process of the chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1248–1254, 2003
Modification of poly(octadecene‐alt‐maleic anhydride) films by reaction with functional amines
Authors: Schmidt Ute , Zschoche Stefan , Werner Carsten
Published: December 2002

Thin films of poly(octadecene‐alt‐maleic anhydride) on top of Si wafers and glass plates were modified by reactions with different functional amines to be used in future studies on the relevance of certain molecular surface properties for the covalent immobilization of proteins. For that aim, a strategy was developed and applied to convert the anhydride moieties of the copolymer by functional amines into side chains bearing hydrophilic groups of acidic (carboxylic acid, sulfonic acid), basic (amines), or neutral (poly(ethylene oxide) (PEO), glucose) character. The modification of the copolymer films was achieved through the two‐step formation of a cyclic imide, which was very stable in aqueous solution. Depending on the reactivity of the applied amine, the adjustment of the reaction time was suitable for the preparation of partially converted surfaces of the polymer film. Degrees of modification between 5 and 30% (according to X‐ray photoelectron spectroscopy data) were obtained. Annealing the modified polymer films induced efficient back‐formation of the anhydride groups. By reaction of the layered polyanhydrides with highly crosslinked diamines, amine‐functionalized polymer films were produced that were capable of binding secondary polyanhydride layers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1255–1266, 2003
Acetylation of wheat straw using simplified procedure and ultrasonic irradiation
Authors: Sun Run‐Cang , Sun X. F.
Published: December 2002

An investigation of the acetylation of wheat straw with acetic anhydride using a simplified procedure and with or without ultrasonic irradiation was undertaken. The new procedure greatly shortened the reaction time and simplified the chemical recovery. Acetylation weight gains of 15.8% can be achieved in 1 h at 120°C without ultrasound assistance. At the same reaction conditions but with ultrasound assistance at 60°C for 5 min, a weight percent gain (WPG) value of 15.0% was obtained, indicating a slightly negative effect of ultrasonic irradiation on the rate of acetylation without solvents or catalysts. However, a positive sonication effect on the solubility of low molecular materials, mainly extractives, was found in all the cases of the reactions. The characterization of acetylated wheat straw was performed by FTIR, solid‐state 13C‐NMR, and thermal studies, which provided evidence for acetylation. The thermal stability of acetylated straw was found to be higher than that of unmodified wheat straw. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1277–1284, 2003
1,6‐hexanediol diacrylate‐crosslinked polystyrene: Preparation, characterization, and application in peptide synthesis
Authors: Arunan C. , Pillai V.N. Rajasekharan
Published: December 2002

A copolymer of 1,6‐hexanediol diacrylate (HDODA) and styrene was prepared by a suspension polymerization method. The resin was characterized by infrared and carbon‐13 cross‐polarization magic‐angle spin (13C CP‐MAS) spectroscopy. The topology of the resin was examined by scanning electron microscopy (SEM). The polymer swells extensively in common solvents used for peptide synthesis. The resin exhibited chemical stability even in neat trifluoroacetic acid. The applicability of the new resin was demonstrated by synthesis of Val‐Ala‐Val‐Ala‐Ala‐Gly, Gln‐Val‐Gly‐Gln‐Val‐Glu‐Leu‐Gly, and Val‐Gln‐Ala‐Ala‐Ile‐Asp‐Tyr‐Ile‐Asn‐Gly. Comparative synthetic studies showed that the new resin is superior to divinylbenzene (DVB)‐based resin in the case of the synthesis of hydrophobic peptide sequences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1290–1296, 2003
Lignocellulosic flour‐reinforced poly(hydroxybutyrate‐co‐valerate) composites
Authors: Dufresne Alain , Dupeyre Danièle , Paillet Michel
Published: December 2002

Residual lignocellulosic flour from spruce and ground olive stone was used as a natural filler in poly(hydroxybutyrate‐co‐valerate) (PHBV)‐based composites. The morphology and the thermal properties of these composites were investigated by scanning electron microscopy and differential scanning calorimetry, respectively. Lignocellulosic fillers acted as nucleating sites for the crystallization of PHBV and strongly enhanced its degree of crystallinity. Dynamic mechanical analysis and tensile properties of these materials were also studied. A significant reinforcing effect was displayed by dynamic mechanical analysis at temperatures higher than the glass–rubber transition of the matrix. In addition, for low‐particle‐size spruce, a stabilization of the modulus was observed up to 500 K. High‐strain tensile properties did not show any reinforcing effect. This apparent disagreement was explained by the poor adhesion between the hydrophilic lignocellulosic filler and the hydrophobic polymeric matrix. To validate this hypothesis, the experimental data were compared with predicted data involving the percolation concept. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1302–1315, 2003
Polymer‐supported iminodiacetamides for selective mercury extraction
Authors: Sonmez Hayal Bulbul , Senkal B. Filiz , Bicak Niyazi
Published: December 2002

A new polymeric resin with iminodiacetamide functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfone amide‐based resin with a 9.6 mmol g−1 amide content is able to selectively sorb mercury over many metal ions, including Cd(II), Zn(II), Fe(III), and Pb(II). Among these, Cd(II) and Zn(II) ions are not sorbed at all, and Fe(III) and Pb(II) ions show only trace absorptions (0.58 and 0.17 mmol/g, respectively) under the same conditions. The selectivity of the resin, its high mercury loading capacity (4.23 mmol g−1), and its ability to regenerate via acetic acid make it a promising material for the large‐scale selective separation of mercuric ions from aqueous mixtures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1316–1321, 2003
The adsorption of Cu(II) ion from aqueous solution upon acrylic acid grafted poly(ethylene terephthalate) fibers
Authors: Karakışla Meral
Published: December 2002

This study is concerned with the investigation of the adsorption properties of acrylic acid grafted poly(ethylene terephthalate) fibers by the use of Cu(II) ions in aqueous solutions. Influence of pH, graft yield, contact time, concentration of the ion, and reaction temperature on the amount of ion adsorbed upon reactive fiber were investigated. The time in which the adsorption reached to the equilibrium value was determined as 1 h. The adsorption isotherm of Cu(II) ion was found to be a Langmuir type and the heat of adsorption was calculated as −10.1 kJ mol−1. It was observed that the adsorbed Cu(II) ion upon acrylic acid grafted poly(ethylene terephthalate) fibers could be recovered in acidic media. The fiber could also readsorb Cu(II) ions without losing its activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1216–1220, 2003
Characterization of polymer‐layered silicate (clay) nanocomposites by transmission electron microscopy and X‐ray diffraction: A comparative study
Authors: Morgan Alexander B. , Gilman Jeffrey W.
Published: December 2002

Several polymer‐layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide‐angle X‐ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene‐g‐maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d‐spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand‐alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003
Extension of Peto's Test by Attribution of Tumor Lethality in the Absence of Cause‐of‐Death Information
Authors: Moon Hojin , Ahn Hongshik , Kodell Ralph L.
Published: December 2002

A new statistical testing approach is developed for rodent tumorigenicity assays that have a single terminal sacrifice or occasionally interim sacrifices but not cause‐of‐death data. For experiments that lack cause‐of‐death data, statistically imputed numbers of fatal tumors and incidental tumors are used to modify Peto's cause‐of‐death test which is usually implemented using pathologist‐assigned cause‐of‐death information. The numbers of fatal tumors are estimated using a constrained nonparametric maximum likelihood estimation method. A new Newton‐based approach under inequality constraints is proposed for finding the global maximum likelihood estimates. In this study, the proposed method is concentrated on data with a single sacrifice experiment without implementing further assumptions. The new testing approach may be more reliable than Peto's test because of the potential for a misclassification of cause‐of‐death by pathologists. A Monte Carlo simulation study for the proposed test is conducted to assess size and power of the test. Asymptotic normality for the statistic of the proposed test is also investigated. The proposed testing approach is illustrated using a real data set.
Influence of hydrogen on SiO2 thick film deposited by PECVD and FHD for silica optical waveguide
Authors: Kim Y.T. , Cho S.M. , Seo Y.G. , Yoon H.D. , Im Y.M. , Yoon D.H.
Published: December 2002

Silicon dioxide (SiO2) thick films have been deposited by plasma enhanced chemical vapor deposition (PECVD) and flame hydrolysis deposition (FHD). PECVD SiO2 films were obtained at low temperatures (<350 °C) by the decomposition of the appropriate mixture of (SiH4+N2O) gases under suitable rf power and N2O/SiH4 ratio. For low N2O/SiH4 ratio, a refractive index(n) value close to 1.50 is obtained. The deposition rate increased with the increase of rf power. FHD SiO2 films were produced by the flame hydrolysis reaction of halide materials such as SiCl4, POCl3 and BCl3 in an oxy‐hydrogen torch. The porous SiO2 layer, under the POCl3/BCl3 ratio deposition condition, has to be consolidated by annealing at around 1300 °C.
Anharmonicity in GaTe layered crystals
Authors: Aydinli A. , Gasanly N.M. , Uka A. , Efeoglu H.
Published: December 2002

The temperature dependencies (10‐300 K) of seven Raman‐active mode frequencies in layered semiconductor gallium telluride have been measured in the frequency range from 25 to 300 cm‐1. Softening and broadening of the optical phonon lines are observed with increasing temperature. Comparison between the experimental data and theories of the shift of the phonon lines during heating of the crystal showed that the experimental dependencies can be explained by contributions from thermal expansion and lattice anharmonicity. Lattice anharmonicity is determined to be due to threephonon processes.
Structure and electrochemical behaviour of Bis[N‐(4‐methylphenyl)salicylaldimine]copper(II) N,N′dimethylformamide solvate
Authors: Tatar Yildirim L. , Emregul K. C. , Kurtaran R. , Atakol O.
Published: December 2002

The molecular model of mononuclear complex formed, through a reaction between N‐(4‐methylphenyl)salicylaldimine and CuII ion was determined using x‐ray diffraction method. The CuII coordination was found to have a distorted square‐planar structure and a cis coordination geometry was observed within the surrounding of the copper. The electro chemical behaviour of the mononuclear copper complex was studied with cyclic voltammetry.
Current sensorless speed servo system of a PM motor based on the current estimation method
Authors: Ohishi Kiyoshi , Nakamura Yusuke
Published: December 2002

This paper proposes a new speed servo system for a PM motor without a current sensor, which is constructed by the current simulator of a PM motor. The proposed speed servo system is simple and economical. The sensor of the proposed system is only a position sensor used as an encoder. Hence, the proposed speed servo system has little influence on the switching noise of a PWM inverter. Moreover, the resolution of the proposed current simulator can be higher than that of the conventional actual feedback system.

In this paper, the experimental results point out that the proposed current sensorless speed servo system has the desired current and speed response. The current waveform of the proposed system is smooth and clean. Moreover, this paper proposes a new identification algorithm for motor resistance Ra and main flux Φfa by using only a position sensor. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(3): 64–73, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10084