bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium Phosphate Cement (CPC): A Critical Development Path
Authors: Tofighi Aliassghar , Schaffer K. , Palazzolo R.
Published: March 2009

The first generation of synthetic bone substitute materials (BSM) was initially investigated in the mid 1970s using hydroxyapatite (HA) as a biomaterial for remodeling of bone defects. The concepts established by CPC pioneers in the early 1980s were used as a platform to initiate a second generation of BSM for commercialization. Since then, advances have been made in composition, performance and manufacturing. A self-setting and injectable calcium phosphate cement (CPC) based on amorphous calcium phosphate (ACP) with calcium to phosphate (Ca/P) atomic ratio less than 1.5, combined with dicalcium phosphate dihydrate (DCPD or brushite, seeded with apatite), is proposed. Amorphization of raw material was observed following high energy mechano-chemical processing. Upon hydration, the cement hardened in less than 3 minutes at 37°C and reached a maximum compressive strength of about 50 MPa. The final product was a low crystalline calcium deficient carbonated apatite similar to the composition and structure of bone mineral. In vivo performance of this cement in mediating bone healing was compared to α-BSM® in a rabbit femoral defect model. Performance characteristics of some commercially available CPC products are compared. The concerns of CPC designers and the needs of product users (surgeons) are discussed.
Effect of Octacalcium Phosphate Ionic Dissolution Products on Osteoblastic Cell Differentiation
Authors: Anada Takahisa , Araseki Akihiro , Matsukawa Shou , Yamasaki Tomokazu , Kamakura Shinji , Suzuki Osamu
Published: March 2009

Our previous studies suggested that synthetic octacalcium phosphate (OCP) enhances bone
regeneration more than hydroxyapatite (HA). However, the molecular mechanisms to induce
osteogenic phenotype in osteoblast by OCP have not been identified. OCP tended to convert into an
apatite structure in vivo and in vitro, and its process was accompanied by calcium consumption from
the surrounding solution and the release of phosphate ions into the solution at a physiological
condition. The present study was designed to investigate whether the dissolution of ionic products of
OCP affects on proliferation and differentiation of mouse bone marrow stromal ST-2 cells in vitro.
The number of cells treated with OCP-conditioned medium was slightly decreased in comparison to
that of control at day 7. On the other hand, the level of alkaline phosphatase activity increased in
OCP-conditioned medium. These results demonstrated that OCP is capable of inducing osteoblastic
cell differentiation in ST-2 cells.
Foamed β-Tricalcium Phosphate Scaffolds
Authors: Montufar Edgar Benjamin , Gil C. , Traykova Tania , Ginebra M.P. , Planell Josep A.
Published: March 2009

The design and processing of 3D macroporous bioactive scaffolds is one of the milestones for the progress of bone tissue engineering and bone regeneration. Calcium phosphate based ceramics are among the most suitable materials, due to their similarity to the bone mineral. Specifically, beta-tricalcium phosphate (β-TCP) is known to be a resorbable and bioactive material, with well established applications as bone regeneration material. The aim of this work is to explore a new route to obtain β-TCP macroporous scaffolds starting from calcium phosphate cements. To this end foamed calcium phosphate cement, composed of alpha tricalcium phosphate as starting powder was used as initial material. The set foamed structures, made of calcium deficient hydroxyapatite (CDHA) were sintered to obtain the final β-TCP macroporous architecture. The interconnected macroporosity was maintained, whereas the porosity in the nanometric range was strongly reduced by the sintering process. The sintering produced also an increase in the mechanical properties of the scaffold.
In Vitro Biomineralization Induced by Self-Assembled Extracellular Matrix Proteins
Authors: Ba X. , Meng Y. , Huang Y. , Kwak S.Y. , Ge S. , Qin Y. , DiMasi E. , Füredi-Milhofer Helga , Pernodet N. , Rafailovich Miriam
Published: March 2009

Extracellular matrix (ECM) proteins play an essential role during biomineralization in bone and engineered tissues. In a previous study [1], we showed that calcite preferentially nucleated on pure elastin fibers. However, the actual cellular ECM fibers are composed of a combination of proteins, primarily collagen, fibronectin and some elastin. Here we follow the calcium carbonate- and calcium phosphate- mineralization process in vitro when these ECM proteins are combined and determine the differences between these proteins in the biomineralization process. The surface morphology and mechanical properties of the protein fibers during the early stages were probed by atomic force microscopy (AFM) and shear modulation force microscopy (SMFM). The nucleation of the mineral crystals on the protein matrices was investigated by scanning electron microscopy (SEM). Preliminary data showed that the moduli of all protein fibers increased at the early stages, with collagen having the largest increase in supersaturated calcium bicarbonate solution. In metastable calcium phosphate solutions the modulus of the mixed elastin-fibronectin fibres increased to a greater extent than the moduli of the fibers composed of the single proteins. Longer exposure in the mineral solutions led to the formation of crystals templated along the self-assembled fiber structures.
Apatite Formation on α-Tricalcium Phosphate/Poly(D,L-Lactide-Co-Glycolide) Nanocomposite
Authors: Yang Z. , Thian E.S. , Brooks Roger A. , Rushton Neil , Best Serena , Cameron Ruth
Published: March 2009

In this study, a biocomposite comprising nanostructured α-tricalcium phosphate (α-TCP) in a poly(D,L-lactic-co-glycolic acid) (PLGA) matrix was fabricated by a modified solution evaporation method. As a potential temporary bone fixation and substitution material, its bioactivity was evaluated by its ability to form bone-like apatite layer in simulated body fluid (SBF). Owing to the increased surface area covered by the osteoconductive bioceramic of α-TCP, rapid apatite formation was observed. After 7 days of immersion, enhanced nucleation of apatite was observed on the nanocomposite. At day 14, dense lamellar-like apatite was formed on the nanocomposite whilst apatite nucleation had only just started to develop on the surface of pure PLGA. At the same time, a preliminary in-vitro cell culture study was conducted using human osteoblast-like (HOB) cells. A significant increase in cell number with culturing time was observed for the nanocomposite. After 9 days incubation, a confluent lamellar-like apatite layer was formed on the composite surface. This apatite layer was also shown beneath the proliferating HOB cells at Day 16.
Release of Growth Factors from Gelatin Microsphere/CaP Composites
Authors: Habraken W.J.E.M. , Boerman O.C. , Wolke Joop G.C. , Mikos Antonious G. , Jansen John A.
Published: March 2009

Composites of gelatin microspheres and injectable calcium phosphate cement were
prepared to increase cement resorption and improve tissue ingrowth. To further enhance these
properties, osteoinductive growth factors can be introduced into the microspheres. In this study, the
in vitro release of preset gelatin microsphere/CaP composites was followed for 6 weeks by use of
125I-labelled rhBMP-2, rhTGF-β and rh-bFGF. Results for all gelatin microsphere composites
showed a release curve that consisted of a small burst, followed by a sustained release. The
magnitude of the sustained release was dependent on the growth factor used, and showed a slight
dependency on the loading method and type of gelatin. Furthermore, no differences in release
pattern or efficiency were found when growth factor concentration increased.
Rigid Hydroxyapatite-Alginate Beads for Sustained Release of Paclitaxel
Authors: Ikoma Toshiyuki , Yoshioka Tomohiko , Nakamura Satoshi , Hanagata Nobutaka , Abe Tetsuya , Sakane Masataka , Ochiai Naoyuki , Tanaka M.
Published: March 2009

Rigid hydroxyapatite (HAp)-alginate beads were prepared as drug delivery carriers for an
anti-cancer drug, paclitaxel (Taxol). Paclitaxel was loaded into the HAp microparticle in process of a
spray-drying technique. The HAp-alginate beads including paclitaxel were obtained by a droplet
method into barium solution as ionic cross-linkage and dehydration. Cross-sectional analyses
indicated the homogeneity of HAp microparticles and barium ions inside the bead. The ratio of
alginate to HAp in the beads dominated both mechanical and swelling properties. Drug-release
experiment demonstrated the sustained release of paclitaxel from the beads cross-linked with barium
ion for 7 days.
Electrochemical Deposition of Apatite on Titanium Substrates by Using Pulse Current
Authors: Masakazu Kawashita , Hayakawa Tomoyasu , Takaoka Gikan H.
Published: March 2009

An apatite layer was successfully formed on titanium substrates by electrochemical
deposition under a pulse current in a metastable calcium phosphate solution, which had 1.5 times the
ion concentrations of a normal simulated body fluid, but did not contain MgCl2·6H2O, at 40 °C for 30,
60, 90 and 120 minutes at the average current density of 10 mA/cm2. The thickness of the apatite layer
was increased with increasing deposition time. The pulse-current deposition produced the thicker
apatite layer than the direct-current deposition, and gave some effects on the surface morphology of
the apatite. The pre-treatment using acid solution gave a better adhesive between apatite and substrate.
It is expected that the present electrochemical deposition under a pulse current will be useful to
rapidly coat apatite on metallic materials.
Structure and In Vitro Solubility of Silicon-Substituted Hydroxyapatite
Authors: Kanaya Tomoko , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi , Fujii Eiji , Kawabata Kouji , Gasqueres Georgiana , Bonhomme Christian , Babonneau Florence
Published: March 2009

Hydroxyapatite (HAp) and Si-containing hydroxyapatite (SiHAp) particles were
synthesized by a wet chemical method. Local structures around Si, P and H in the hydroxyapatites
were analyzed by solid-state magic-angle spinning nuclear magnetic resonance spectroscopy. In
vitro solubility of those SiHAp particles was evaluated by soaking them in acetic acid/acetate buffer
solution (pH=4.0) at 36.5°C. As the Si content increased, the in vitro solubility of the SiHAp
particles increased, while their crystallite size changed little.
Changes in the Activity of Osteoblast Like Cells with Sol-Gel Derived Hydroxyapatite and Zirconia Nanocoatings
Authors: Lewis Kanthi , Valenzuela S.M. , Ben-Nissan Besim
Published: March 2009

When producing implant materials, achievement of optimal bioactivity and biocompatibility are essential. Nanocoatings can provide an efficient cost effective way to alter the interactions of the implant material with its destined “host” environment. Nanocoatings of sol-gel derived carbonated hydroxyapatite (HAp) and zirconia were produced in this study. The surfaces were characterised by Fourier transform infrared spectroscopy (FTIR) and light microscopy. Cell adhesion, proliferation and viability, as well as expression of alkaline phosphatase (ALP is an indicator of bone formation) were assessed as indicators of biocompatibility. Our results have shown that sol-gel derived nano crystalline HAp acts as an ideal surface for implant coatings.
Effect of Sintering Condition, Sandblasting and Heat Treatment on Biaxial Flexure Strength of Zirconia
Authors: Ban Seiji , Sato Hideo , Suehiro Y. , Nakanishi H. , Nawa Masahiro
Published: March 2009

The effect of sintering condition, sandblasting and heat treatment on biaxial flexure
strengths of the zirconia/ alumina nanocomposite stabilized with cerium oxide (Ce-TZP/Al2O3
nanocomposite, referred to NANOZR) was evaluated in comparison to that of yttria stabilized
tetragonal zirconia polycrystals (Y-TZP). The disc-shaped specimens of NANOZR and Y-TZP
were cut from the full-sintered or middle-sintered ones. The discs cut from the middle-sintered
ones were finally sintered at the same temperature for the full-sintered one. These four kinds of
disc were treated in various conditions combined with the sandblasting, the heat treatment, and the
storage. The biaxial flexure strength of both middle- and full-sintered Y-TZP decreased with the
autoclaving, whereas those of both NANOZR did not change with it. The monoclinic content of
both the materials increased with the sandblasting and decreased with the heat treatment.
Regardless of the sintering condition, the monoclinic content of the Y-TZP dramatically increased
with the autoclaving and those of NANOZR remarkably increased with the sandblasting.
Regardless of the different surface roughness, the biaxial flexure strengths of both materials
strongly depended on the content of monoclinic ZrO2 on the surface.
The Reactivity of CaTi4(PO4)6 with Alumina and Y-TZP Ceramics
Authors: Beranič Klopčič Sabina , Pribošič Irena , Kosmač Tomaž , Ploska Ute , Berger Georg
Published: March 2009

The reactivity of CaTi4(PO4)6 (CTP) with alumina and yttria-stabilized zirconia (Y-TZP)
ceramics was studied. CTP powder was synthesized and composites with commercial alumina or
zirconia matrices containing 10 wt% of CTP were prepared. They were sintered at different
temperatures and characterized using XRD, SEM, and EDX analyses. The results showed that the
alumina/CTP and Y-TZP/CTP composites start to react below 1000 °C. In the alumina/CTP
composite the first reaction product, detected at 970 °C, was AlPO4. At temperatures above 1280 °C
TiO2 and CaTiO3 were also formed and no CTP peaks could be detected using XRD analysis. The
composite sintered at 1500 °C consisted of Al2O3 matrix, AlPO4, TiO2, CaTiO3 and Al2TiO5. The
reaction products formed in the Y-TZP/CTP composite at 970 °C were TiO2 and Ca2Zr7O16. At
higher sintering temperatures, 1280 °C and above, CTP was no longer present, Ca2Zr7O16
decomposed, forming CaO2 and ZrO2, and Y2O3 was consumed to form YPO4. Consequently, upon
cooling to room temperature the matrix phase transformed to monoclinic ZrO2. Based on these
results it can be concluded that CTP is not a suitable bioactive second phase for the fabrication of
CTP composites with alumina or zirconia matrices.
In Vitro Bond Strength of Based-Coated Zirconia Brackets for Orthodontics
Authors: Lee Myung Hyun , Choi Han Shin , Oh K.S. , Kim Y.K. , Yim H.B. , Lee Deuk Yong , Oh Nam Sik
Published: March 2009

In Vitro Bond strength of base-coated (Y, Fe)-TZPs (yttria and iron co-doped tetragonal
zirconia polycrystals) were investigated to evaluate the feasibility for the ceramic bracket applications.
Pre-sintered (Y,Fe)-TZP brackets were machined, abraded and spray-coated with granule slurries
containing 10~50 wt% of flux. Better adhesion to the base surface of the brackets was observed by
raising the amount of flux in the slurries. It may be because of the fusion and the collapse of the
granules as a result of the high amount of flux. The one-way analysis of variance indicated that there
were significant differences in bond strength measurements between the experimental groups except
30% and 50% flux content groups. The Weibull distribution revealed that 50% flux content group is
the best with a high characteristic strength value. Mean ARI values exhibited large differences and
ranged from 1.6 for 50% flux content group to 3.0 for non-coated group. Adhesive remnant of
adhesive resin was decreased by increasing the flux up to 50%. Reduction in adhesive remnant is
likely due to the higher bonding of adhesive resin to granules. No teeth and bracket damages were
found in any teeth de-bonded by shear force. The base-coated brackets with higher strength (11.5
MPa) and no adhesive remnant were newly proposed for the orthodontics applications.
Surface Structure, Hydration and Cationic Sites of Nanohydroxyapatite
Authors: Bertinetti Luca , Tampieri Anna , Landi Elena , Bolis V. , Busco C. , Martra Gianmario
Published: March 2009

In this work, we studied the surface/water interaction properties of a pure calcium
hydroxyapatite (HA) and their modifications as a consequence of the partial Ca2+/Mg2+ (MHA)
substitution by means of IR spectroscopy and microcalorimetry of adsorbed water. IR data
indicated that water molecules in direct contact with the surface of HA are coordinated to surface
cations and experience H-bond significantly stronger than in liquid water. The heats of adsorption
associated to such interactions are very high, being twice-triple the heat of liquefaction of water.
Interestingly, water experiences H-bond higher than in its bulk liquid state also in the second layer.
Finally the entering in the material of Mg2+ ions was shown to significantly affect the affinity of the
material toward water and the properties of its hydration layers.
Microtensile Bond Strength of Dual-Cured Resin Luting Cements to Dentin by the Type of Dentin Adhesives
Authors: Kim S.Y. , Kim D.W. , Park S.H. , Choi K.K.
Published: March 2009

This study was performed to investigate the bond strength between 4 dentin adhesives
and resin luting cements by means of μTBS test. The materials used in this study were four resin
cements (Choice, Panavia F, RelyX ARC, Bistite II DC), one 3-step adhesive (All-Bond2), one 2-
step self-etching adhesive (Clearfil SE-Bond) and two 1-step self-etching adhesives(Prompt L-Pop
and One-Up Bond F). Combination of 4 different dentin adhesives with 4 resin cements made up 16
experimental groups. Extracted human mandibular third molars without caries and restoratives were
stored in saline and used within 1 month of extraction. All adhesive systems and resin cements were
manipulated and applied to the dentin surfaces according to the manufactures’ instructions. The
resin composite “overlays” prepared with 6 mm thickness (Tescera, Bisco Inc., Schaumburg, IL,
USA) were luted with each resin cement. Each sample was measured μTBS.
1-step self-etching adhesives coupled with all resin luting cements used in this study resulted in
lower bond strength except of OU-PA group. When Choice, RelyX ARC and Bistite II were used,
Clearfil SE-Bond showed significantly higher μTBS values than 1-step self-etching adhesives
(p<0.05). Clearfil SE-Bond did not show significant μTBS values than All-Bond 2 that is
conventional 3-step dentin adhesive (p>0.05).
Preparation of Leucite Powder with Controlled c-Phase Fraction for a Variety of Dental Applications
Authors: Kloužková Alexandra , Mrázová M. , Kohoutková M.
Published: March 2009

Leucite (KAlSi2O6) is the main crystalline phase in feldspathic dental materials used for ceramic-fused-to-metal restorations. It occurs in two modifications, low temperature – tetragonal and at temperatures above 600 °C high temperature – cubic modification. The aim of this work was to develop a low-temperature preparation technology of submicron leucite powders with varying ratio of tetragonal and cubic modification. The results show that analcime synthesized in hydrothermal conditions is the suitable precursor for the preparation of leucite with controlled fraction of the c-modification. Homogenous t-leucite having particle size from 2 - 4 μm was prepared by 4h ion-exchange in 4M KCl. Partially stabilized c-leucite was obtained by dual ionexchange; 4h in 4M CsCl led to 48 % of c-modification in the final product.
Calcium Phosphate Coated Rapid Prototyped Porous Titanium Scaffolds
Authors: Lopez-Heredia Marco A. , Fellah Borhane H. , Pilet Paul , Leroux C. , Dorget M. , Weiss Pierre , Sohier J. , Layrolle Pierre
Published: March 2009

Porous Titanium Scaffolds were produced by using a rapid prototyping technique. These
scaffolds were either coated or not with a calcium phosphate coating via an eletrodeposition
method. Rat bone marrow mesenchymal stem cells were cultured on the scaffolds at a density of
106 cells/scaffold for a period of 3 days. Cell proliferation was measured by using the Alamar Blue
assay. The scaffolds were observed by SEM and polarized light microscopy. Constructs were then
implanted subcutaneously for 4 weeks in syngenic rats. Cells proliferated well after seeding. After
subcutaneous implantation, histology and SEM revealed the presence of uniform coatings as well as
Ca and P deposits in the non-coated scaffolds suggesting mineralization.
Newly Unsintered Bone Graft Substitutes with Controlled Porosity
Authors: Klinkenberg Ernst Dieter , Neumann Hans Georg , Bulnheim Ulrike , Rychly Joachim , Bader Rainer
Published: March 2009

A new porous unsintered CaP-compound material for bone graft substitutes is described.
A modified sol-gel freeze casting process enables preparation of sophisticated shaped bodies. By
adapted chill molds and the variation of the freeze process the porosity of the material can be
engineered, i.e. the pore size distribution as well as the preferred direction of the oblong pores.
Thereby controlled osteoconduction can be achieved. The mechanical properties of the CaP
compounds are improved by embedding supporting structures. Due to its huge inner surface the
material can serve as a scaffold supplied with agents.
Strontium Activated Bioactive Cellulose Scaffolds
Authors: Brandt Heike , Greil Peter , Müller Frank A.
Published: March 2009

Knits made of cellulose are promising scaffolds for bone tissue engineering applications
due to their multi-scale interconnected porosity, biocompatibility and adjustable biodegradability.
The approach of this study combines the modification of cellulose with strontium to generate
scaffolds capable of forming bone like apatite during exposure to physiological solutions and the
release of strontium as an active agent, that might encourage the development of new bone tissue.
The Sr-release kinetics during static exposure to simulated body fluid is dominated by an
accelerated Sr-release in the initial state followed by a reduced release corresponding to a diffusion
controlled rate. Microstructural analyses indicate that initially precipitated SrCO3 transforms to
SrxCa1-xCO3 solid solutions that subsequently serve as a template for the precipitation of bone like
carbonated hydroxyapatite.
The Osteogenic Behaviour of Silicon Substituted Hydroxyapatite
Authors: Best Serena , Zou Shuo , Brooks Roger A. , Huang Jie , Rushton Neil , Bonfield William
Published: March 2009

Dense and porous HA and Si-HA discs and granules with varying percentages of silicon
substitution have been produced and physically and chemically characterised using scanning
electron microscopy, surface area analysis, porosimetry, density measurement, image analysis, Xray
diffraction, X-ray fluorescence, FT-infrared spectroscopy and in-vitro and in-vivo testing.
Results have shown that cell adhesion in-vitro and bone apposition in-vivo are enhanced by the
presence of silicon substitution in the hydroxyapatite structure. The biological response to the
materials appears to indicate an optimum outcome for levels of silicon substitution of 0.8wt%.
Fabrication of Micro-Grating Structure on Glazed Stainless-Steel by Two-Beam Holographic Method Using Nanosecond Laser Pulses
Authors: Zhang Heng , Zhou Yun , Chen Lin Sen
Published: March 2009

A new method of etching micro-grating structures (MGSs) on the surface of glazed
stainless-steel directly is reported, which makes good use of the interference of nanosecond laser
pulses. Through changing the experimental parameters such as working current of the laser and
source beam diameter, the influences of these parameters on the depth of grooves and duty cycle of
MGSs are analyzed. The results measured with conventional optical microscopy and atomic force
microscopy (AFM) show that the depth of grooves of MGSs varies from 0 nm to 350 nm, the duty
cycle of MGSs changes between 0.4 and 0.9, This method can be used to make a stencil-plate for
nano-imprinting. It extends the application of nanosecond laser in laser-induced microstructures,
and provides a new method for micromachining micro-optical component.
Fractal and Wavelet Methods Used in the Feature Extraction of Machining Processing from 3D Machined KDP Surfaces
Authors: Chen Ming Jun , Pang Qi Long , Wang Jing He , Cheng K.
Published: March 2009

Fractal and wavelet methods have been used in this study to analyze the KDP surfaces machined by accurate milling and SPDT (Single Point Diamond Turning) method respectively. Through the 2D wavelet method, the 3D origin machined surfaces were separated into the 3D overlaying roughness surfaces and 3D material structure surfaces. The overlaying roughness surfaces were composed of a large number of length scales superimposed roughness surfaces that are generated from the various vibrations in the machining process. The wavelet method can analyze the information of spatial frequency (vibrations in the machining process) and fractal method can reveal the intrinsic properties of roughness topography. Compared with the conventional methods, the integration of wavelet and fractal is more suitable to characterize the machined crystal KDP surface.
Stress Birefringence in Photonic Crystal Fibers Used in a Novel Field Installable LC Type Optical Connector
Authors: Lin Samuel I En
Published: March 2009

Photonic crystal fibers (PCFs) have recently attracted a great deal of interest because of
their unique characteristics and many controllable features. They include a wide range of single
mode operation, highly birefringent characteristics (~10-3), high-power light transmission, etc. The
field-installable LC connectors tend to be of the larger connector types in the fiber-to-the-home
(FTTH) distribution units. In these designs, fibers are clamped inside a splice assembly and are
stressed within the connector. In this research, we first developed a novel cam-type mechanism for
field-use LC connector. The fiber stress was analyzed via a commercial available finite element
program. The stress birefringence distributions of single mode fiber and air-silica based PCFs were
calculated by stress photoelastic effect. We further studied the effect of air-hole size on the stressinduced
birefringence of PCFs. The results indicate that stress-induced birefringence decreases as
air-hole size increase. On the other hand, the birefringence increases as applied clamping force
increases on the single mode fiber.
An Improved Data Processing Method in Differential White Light Spectral Interferometry for the Measurement of Thickness of Ultra-Thin Metallic Foil
Authors: Du Yan Li , Yan Hui Min , Zhang Xiu Da
Published: March 2009

The accurate thickness measurement of Ultra-thin rolling metallic foil has an important
role in industrial or some special applications. Unfortunately, commercial thickness meters do not
provide high precision measurements non-destructively. A new spectral-domain interferometric
method for measuring absolute thickness of Ultra-thin metallic foil is proposed here. The thickness
is measured by differential white light spectral interferometer. Two differential Michelson
Interferometers (MI) are used as basic measuring system to obtain the spectral interference fringes
on the spectrometers. The spectral interference between both beams, which shows up a periodic
modulation of the source spectrum with the period dependent on the OPD, serves as an illustration
of a technique for measuring both OPDs and displacements in a range dependent on the source
spectrum width. Therefore, the interference fringes only depend on the OPD due to the thickness of
metallic foil and are unrelated to the position of the foils in the system, which is insensitive to the
vibration. The spectral interference fringes are resolved over a wide spectral range and the absolute
thickness of metallic foil can be calculated by measuring the OPD with a modified extremum
method based on the least root mean square (RMS) deviation. The theoretical analysis and
preliminary experiments indicate that the technique can measure the thickness of foils in the range
of 1μm to 80μm, and it requires less than 50ms within the single measurement. Experimental
results are presented.
Single-Point Diamond Turning of Plasma-Nitrided Stainless Steel
Authors: Chao Choung Lii , Chen Chun Chieh , Chang Chia Jong , Dong Han Shan , Ma Kung Jeng , Hsu Wei Yao , Huang Kuo Cheng , Chao Chung Woei
Published: March 2009

Stainless steel and other ferrous metals are normally classified as not diamond turnable
for the unacceptable tool wear caused by the thermal-chemical reaction between diamond and
ferrous metals. In the present research, stainless steel specimens were plasma nitrided at a relatively
low temperature (<450oC) to prevent the depletion of Cr content at the austenite matrix and to give
a hardened layer where Fe atoms are bonded to nitrogen atom to form γ’-Fe4N. Diamond turning
experiments were subsequently carried out under the following machining conditions: single crystal
diamond tool, cutting speed up to 180 m/min, cut depth up to 5μm and light mineral oil as the
cutting fluid. The results showed that, given the same machining conditions, while rapid tool wear
and poor surface finish were obtained when turning the as-received stainless steel, surfaces with Ra
better than 3nm and no obvious tool wear were achieved when turning the plasma nitrided
specimens
Theoretical Analysis and Experimental Verification of Triangular Fracture Defects of MgO Single Crystal Substrate in Lapping or Polishing Process
Authors: Wang Ke , Kang Ren Ke , Jin Zhu Ji , Guo Dong Ming
Published: March 2009

MgO single crystal is mainly used as substrate for high temperature superconductor film. Surface quality of MgO substrate has significant effect on the function of high temperature superconductor film. MgO single crystal is a typical hard and brittle material, and is easily cleaved along the {100} face, so some defects are always generated on the substrate surface while lapping and polishing, which badly affects the surface quality of the substrate. In this paper, a kind of typical defect, the triangular fracture defect which is on the substrate surface after lapping and polishing, is analyzed in detail. According to the structure characteristics of the MgO single crystal, and based on the dislocation reaction theory, a formation mechanism of the triangular fracture defect in lapping and polishing processes is explored. Through the single grain scratch test in different directions on the polished surface of MgO{100} single crystal substrates, the formation mechanism of triangular fracture defect in lapping and polishing processes is verified. And during the scratch test, the plastic flow of the MgO single crystal material beside the scratch was observed.
Integration of Micro Array Sensors in the MEA on Diagnosis of Micro Fuel Cells
Authors: Lee Chi Yuan , Lee Shuo Jen , Wu Guan Wei
Published: March 2009

The temperature and humidity conditions of a membrane electrode assembly (MEA)
determine the performance of fuel cells. The volume of traditional temperature and humidity
sensors is too large to allow them to be used to measure the distribution of temperature and
humidity in the MEA of fuel cells. Measurements cannot necessarily be made where required. They
measure only the temperature and humidity distribution outside the fuel cells and yield results with
errors that exceed those of measurements made in MEA.
Therefore, in this study, micro-electro-mechanical-systems (MEMS) fabrication technology was
employed to fabricate an array of micro sensors to monitor in situ the temperature and humidity
distributions within the MEA of fuel cells. In this investigation, an array of micro temperature and
humidity sensors was made from gold on the MEA. The advantages of array micro gold
temperature and humidity sensors are their small volume, which enable them to be placed on MEA
and their high sensitivity and accuracy. The dimensions of the temperature and humidity sensors are
180μm × 180μm and 180μm × 220μm, respectively.
The experiment involves temperatures from 30 to 100 °C. The resistance varied from 23.084 to
28.196 /. The experimental results reveal that the temperature is almost linearly related to the
resistance and the accuracy and sensitivity are less than 0.3 °C and 3.2×10-3/°C, respectively. The
humidity sensor showed that the capacitance changed from 15.76 to 17.95 pF, the relative humidity
from 20 to 95 %RH, and the accuracy and sensitivity were less than 0.25 %RH and 0.03 pF/%RH.
An Enhanced Common Path Interference Measurement Method for Optical Refractive Indices
Authors: Wang Cheng Chi , Jang Ming Jyi , Peng Yuan Hung
Published: March 2009

This study presents an enhanced common path interference system designed to measure
the refractive index of crystal optical components. The proposed system is based on the classic
Michelson interferometer and comprises a frequency stabilized helium-neon (He-Ne) laser, a beam
splitter, a fixed mirror, an adjustable mirror, and a light detection system. The waveplate of interest
was clamped to a rotatory motor and positioned between the beam splitter and the fixed mirror. The
refractive index of the waveplate was then derived from the change in rotational angle of the
waveplate as it moved from one position of minimum interference to the next. The measurement
system proposed in this study is simple in construction, straightforward in operation, and robust to
the effects of experimental noise. Furthermore, the system is a non-contact measurement system,
and hence does not damage the optical component of interest. The experimental results are found to
be in good agreement with the theoretical results. Therefore, the proposed system provides a viable
means for the rapid experimental evaluation of the optical characteristics of quartz components.
Improving Machining Accuracy of the EMM Process through Multi-Physics Analysis
Authors: Lee Shuo Jen , Lai J.J. , Lee Yu Ming , Lee Chi Yuan , Yang K.T. , Peng C.W.
Published: March 2009

In this study, the parametric effects of the EMM process were studied by both numerical simulation and experimental tests. The numerical simulation was performed using commercial software, FEMLAB, to establish a multi-physics model which consists of electrical field, convection and diffusion phenomena to simulate the parametric effects of pulse rate, pulse duty, electrode gap and inflow velocity. From the simulated results, the relationship between parameters and the distribution of metal removal could be established. Proper process variables were also chosen to conduct the EMM experiments. After the experiments, the profile of the processed rectangular slot was measured by a Keyence digital microscope. Comparing profile of the processed rectangular slot with the profile of the cathode, the machining accuracy of EMM process could be determined. It could also verify the efficacy of the multi-physics model for predicting machining accuracy. From this study, the effects of parameters such as pulse rate, pulse duty, electrode gap and inflow velocity are better understood. The simulation model could be employed as a predictive tool to provide optimal parameters for better machining accuracy and process stability of the EMM process.
Heat Transfer Investigations of a Nano-Porous Silicon Film Deposited on a Flexible Cyclic Olefin Copolymers Substrate
Authors: Jou Rong Yuan
Published: March 2009

A nano-porous silicon film deposited on a flexible cyclic olefin copolymers substrate is
adopted to insulate the structure at high processing temperature during device manufacturing. In this
study, the thermal conductivity of nano-porous silicon film modeled by Lysenko et al. [7] is
implement to do the one-dimensional heat conduction analysis and to calculate the temperatures
theoretically and numerically. In numerical work, the COMSOL finite-element based package is
used for the numerical computations and effects of applied temperature loading, thickness of nanoporous
silicon layer, and porosity are discussed. As shown in the analysis results, thickness of
200μm has the lowest temperature than other thicknesses, 25μm, 50μm, and 100μm, etc. Porosity
plays a vital effect for thermal insulation. From the analyses, the case of 80% porosity has the larger
temperature decrement than cases of 40% and 60%. It may be attributed to the lower conduction by
higher porosity. Also, these temperatures show good agreement between the theoretical and
numerical results and are consistent to the Lysenko et al. [7] statement for nano-porous silicon film
for thermal insulating material.
Effects of Light Wavelengths on the Performance of Color Absolute Judgments
Authors: Huang Shih Miao , Lin Jui Chang
Published: March 2009

Optically, humans can discriminate between colors as close as 2nm in wavelength in
relative judgment task. However, there is little research to discuss color differences for absolute
color judgments in which the comparison is held in memory. Therefore, the intent of this study was
to explore effects of wavelengths on the Just Noticeable Difference (JND) of absolute judgments in
our perceptual world. A color identification task was utilized to investigate the JND of
wavelengths. In the experiment, the Standard Stimulus Color (SSC) and the Comparison Stimulus
Color (CSC) were successively presented. The SSC which was presented first must be stored in
working memory and recalled when the second color, CSC, is presented. Subjects had to decide if
the CSC matched the SSC. Each CSC was presented four times for each subject in the experiment.
The CSC wavelength that was recognized as different from the SSC twice was designed as a JND
wavelength. Five SSC wavelengths with 100% saturation and 100% lightness were chosen from
the hue circle of HLS color space which included 360 hues. Because the hue circle is a circle, the
CSC may be on both sides of a SSC in the hue circle. The CSC hue which may be located on the
clockwise direction or counter clockwise direction of the SSC was called clockwise direction color
(CD) or counter clockwise direction color (CCD), respectively. The wavelengths expressed with
HLS color space were translated into coordination of CIE1931 (x, y)-chromaticity diagram. The
results indicated that threshold sensitivities varied for different wavelengths on absolute judgment
tasks. The lights with longest or shortest wavelength had greater JNDs than ones with middle
wavelengths for absolute judgment tasks. The comparison of the results of the experiment on
absolute color judgment tasks and MacAdam’s (1942) findings for relative color judgment tasks
were also discussed.
Extrusion Benchmark 2007 – Benchmark Experiments: Study on Material Flow Extrusion of a Flat Die
Authors: Schikorra Marco , Donati Lorenzo , Tomesani Luca , Tekkaya A. Erman
Published: March 2009

The experimental conditions chosen as a reference for the 2007 edition of the extrusion
benchmark and the corresponding main results are summarized in this work. The die design stage is
first explained in order to address the main features of the experiment and its objectives. The die is a
flat one with multiple holes; four angular profiles were produced with different pocket geometries,
the experimental plan being entirely described. The initial temperatures for the billet and the die set,
together with the temperature development during the process strokes are also reported. The results
are shown, for each profile, in terms of final profile length, mean exit speed, global process load,
profile exit temperature.
Seam Welds Modeling and Mechanical Properties Prediction in the Extrusion of AA6082 Alloy
Authors: Donati Lorenzo , Tomesani Luca
Published: March 2009

This work summarizes the outcome of recent research by the authors on modeling the
formation of seam welds in aluminum extrusion and on evaluating the related mechanical properties
on the final products. A profile with a seam weld in the middle section was produced with different
die designs in order to investigate the relation between die design and local welding parameters,
such as contact pressure, temperature, time of contact, strain and strain rate paths. The local welding
conditions were evaluated by complete thermo-mechanical 3D FEM simulation of the processes.
Specimens were extracted from the profiles and tensile tested, the resulting mechanical properties
being discussed with respect to the local welding conditions. The possibility to adopt criteria for
assessing the welding quality is discussed, together with the effect of high speed damage cracking.
Simulation-Based Design of Ram Speed Profile for Isothermal Extrusion
Authors: Li Luo Xing , Zhang H. , Hu J. , Zhou Jie , Duczczyk Jurek
Published: March 2009

Isothermal extrusion is a very much desired technology. However, its implementation in
the light-metal extrusion practice has, up till now, been technologically constrained. In an attempt to
realise isothermal extrusion, a simulation model based on the PID control algorithms was developed
to establish ram speed profiles that could prevent extrudate temperature from further increase after an
initial rise during an extrusion cycle. With this simulation model, extrusion ram speed could be
adjusted in real time according to the simulated exit temperature. A case study was conducted on the
simulated extrusion of a magnesium alloy AZ31B into a hollow profile. The results showed
significantly improved temperature homogeneity not only along the extrudate length but also on its
cross section in the case of extrusion in the isothermal mode with a designed ram speed profile. In
addition, die temperature varied over a narrower range and the force acting on the die face was more
stable over the process cycle, in comparison with extrusion in the conventional iso-speed mode.
Processing and Properties of Ferroelectric Bi4-x La xTi3O12 Ceramics
Authors: Wang Wen , Ke Hua , Zhang Deng Guo , Jia De Chang , Zhou Yu
Published: March 2009

Bi4-xLaxTi3O12 (BLT, x=0, 0.75, 1, 2) ceramic powders were prepared with sol-gel and solid phase reaction processes, respectively. BLT powders were synthesized after decarbonization at 300°C for 1h followed by calcination at 800°C for 2h. The ceramics synthesized with cold isostatic pressing and sintering at 1150°C exhibit a perovskite-like structure. The influence of sintering parameters and La doping content on density, microstructure and dielectric properties of the BLT were discussed. With the increase of La doping content in Bi4-xLaxTi3O12, dielectric constant increases and dielectric loss gradually decreases. The dielectric constant and dielectric loss of Bi4-xLaxTi3O12 (x=2) are 132.7 and 0.012 at 100 KHz, respectively.
Thermal Energy Storage System of Sulfate / Fiber Matrix Composite
Authors: Ren Xue Tan , Zeng Ling Ke , Liu Ping An , Wang Hui
Published: March 2009

The K2SO4-Na2SO4 system was studied by differential scanning calorimetry (DSC) with the
aim of developing a new phase-change thermal energy storage material. The temperature range of phase
change is from 800°C to 1069°C according to the phase diagram. A new shape-stabilized phase-change
material made of molten salts impregnated by capillary forces in a porous-fiber matrix was presented.
These materials were characterized by X-ray diffraction analysis and differential scanning calorimetry
analysis. The results indicated that the compound included 70~80% of molten salts, meanwhile the heat
storage material could keep its shape without any leakage during the heating process.
Analysis on Resistance Coefficients and Optimization of Structure and Properties of Porous Permeable Refractory
Authors: Zhang Mei Jie , Wang Hou Zhi , Gu Hua Zhi , Huang Ao
Published: March 2009

The resistance coefficients through which gas flow permeable refractory are important
properties and have great effect on the gas blowing parameters and gas-liquid two phase flowing
characteristics in the metallurgy furnace such as ladles, tundish. In this paper, the resistance coefficients
were measured according to the Forchheimer’s law. The results show when the gas flow rate is fixed, the
viscosity resistance coefficient and inertia resistance coefficient decrease as the apparent porosity and
average pore diameter increase. The viscous resistance coefficient is more lager than the inertial
resistance coefficient. The resistance coefficients were analyzed by dimensional analysis and the
statistical correlations between the resistance coefficients and parameters of porous permeable refractory
were got based on the experimental data. In order to get high strength at low resistance coefficients, the
raw materials particle degree were adjusted.
Preparation and Characterization of ß-Tricalcium Phosphate via Wet Mechanochemical Treatment
Authors: Yu Tao , Ye Jian Dong
Published: March 2009

In this work, a simple, reproducible and low-cost synthesis method for the preparation of
ß-tricalcium phosphate (ß-TCP) was developed. ß-TCP was prepared via wet mechanochemical
treatment using calcium oxide and calcium hydrogen phosphate as raw materials. XRD and FTIR analysis
indicated that the as-treated precursor was non-stoichiometric, poorly-crystallized carbonated
hydroxyapatite (CHA) resulting from the mechanochemical reaction, and the crystalline ß-TCP powder
was obtained by calcining the precursor at 800°C for 2 hours. SEM observation showed that the addition
of surfactants could eliminate the agglomeration of the powder and well-dispersive ß-TCP powder with a
particle diameter between 0.1 and 2.0 2m can be obtained.
Calcium Polyphosphate Bioceramics with Different Ca/P Ratios
Authors: Wei Shan Shan , Tian Yi Ping , Cheng Qiang , Li Hui , Guo Ling Hong
Published: March 2009

Calcium polyphosphate (CPP) bioceramics with different Ca/P ratios were fabricated. It was shown that the contents of CPP in the sintered ceramics decrease with the increasing Ca/P ratios (0.5-1.0) of the precursors. The higher the Ca/P ratios of precursors were, the more complex the phases of polymerization were. The compressive strengths of ceramics sintered at the same temperature showed a linear decreasing tendency with the increasing Ca/P ratio.
Structure of Carbonated Hydroxyapatite Based on Rietveld Method
Authors: Ran Xu , Ran Jun Guo , Gou Li , Chen Ji Yong , Luo Jiao Min
Published: March 2009

The crystalline structures of B-type carbonated hydroxyapatite (CHA) powders sintered at 700,
900 and 1100°C, respectively, were studied by Rietveld analysis of powder X-ray diffraction (XRD) data.
A series of structure parameters, including lattice parameters (a and c), bond length and the distortion
index of PO4 tetrahedron (Dind) were calculated by Rietveld method to characterize the fine structure of
CHA. The broadening effect of XRD reflections was separated to calculate the micro-strain and
crystalline size. The results showed that CHA become more stable with the increase of sintering
temperature, but the CO3
2- is almost lost at temperature of 1100°C. The quantitative results about crystal
structure of CHA based on crystalline structure simulated by Rietveld method are obtained.
Preparation and Characterization of APTES Modified Bioglass
Authors: Ren Li , Yang Tian Yi , Zhao Ying Gang , Zhao Na Ru
Published: March 2009

Bioglass (BG) particles were treated by 3-aminopropyltriethoxysilane (APTES) in order to
improve the interface compatibility with polymer materials. The surface structures of modified BG were
characterized through Fourier transformed infrared spectroscopy with attenuated total reflectance accessory,
thermogravimetric analysis, differential scanning calorimetry analysis and X-ray photoelectron
spectroscopy. The results showed that APTES was successfully grafted on the surface of BG. The biomineralization
properties of APTES modified bioglass were also studied through FTIR, XRD and SEM.
Results showed that hydroxylcarbonateapatite (HCA) was formed on the surface of modified BG after
soaked into SBF solution. It was shown that the APTES modified BG could possess good mineralization
properties and could be intended as a composition of scaffolds for bone tissue engineering applications.