bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Efficiency Mirror Grinding of AlN by Ultra-Precision Plane Honing
Authors: Suzuki Shinya , Yoshihara Nobuhito , Yan Ji Wang , Kuriyagawa Tsunemoto
Published: March 2009

Plane honing machining of aluminum nitride (AlN) was investigated in this study. AlN has
advantageous thermal and dielectric characteristics and is in great demand as a semiconductor
mounting board or packaging parts material. However, as AlN is a sintered material, the AlN grains
readily detach during machining making it difficult to obtain fine surface roughness at high efficiency.
In previous studies, we have developed a new plane honing method that makes it possible to grind
hard and brittle materials. In this paper, plane honing experiments of AlN were carried out using a
resinoid or vitrified bond wheel. Fine surface roughness could be obtained using the resinoid bond
wheel but there was low-machining efficiency due to burying and detachment of abrasives. The
vitrified bond wheel, however, enabled high efficiency grinding but resulted in traces of detached AlN
grains forming at the machined surface. Highly efficient mirror grinding of AlN could be achieved by
using a vitrified bond wheel for semi-finishing and a resinoid bond wheel for finishing.
High Speed Lapping Ellipsoid by Means of a Lapping Tool Bending Method
Authors: Yang J.D. , Liu Q. , Tian C.L. , Guo J.W. , Feng Y.H.
Published: March 2009

This paper discusses a new lapping ellipsoid method, which combines high-speed
lapping technology with solid abrasives and lapping tool bending method. In this method, a bending
moment is acted on lapping tool with solid abrasives, which makes it bend to form a shape on its
working surface, which is the same as generant of workpiece shape. This kind tool is used in
forming lapping on a high speed lapping machine.
With the development of science and technology, the requirements for optics systems become
higher and higher, e.g. good quality of imaging, little loss light energy, small size and light weight
etc. It is difficult to reach above requirements by using traditional sphere lens/mirrors in optics
systems. Aspheric optics elements can be used to solve these problems. In optics systems, by using
aspheric optics elements, the number of optics elements can be reduced, the system structure can be
simplified, the weight and size of the system can be reduced, light energy loss can be reduced too,
imaging errors can be avoided and imaging quality can be improved. Ellipsoid is a kind of surface
being used widely within all kinds of aspheric surfaces. The main purpose of this paper is to
introduce a method of lapping this kind of surface at high speed.
Improvement of Surface Texture of Stainless Steel by Utilizing Dry Blasting - 3rd Report: Effect of Blasted Texture on Adhesion of Plating -
Authors: Minaki Kazushi , Kitajima Koichi , Nakahira Yu , Minaki K. , Izawa Moriyasu , Tosha Katsuji
Published: March 2009

Recently, wet blasting is generally used such as liquid honing and water jet machining in surface before plating of stainless steel. The outstanding feature of wet blasting is to prevent generation of static electric charge, to use micro abrasive grain, and to have cushioning for workpiece. On the other hand, the disadvantage of wet blasting is to generate corrosion of equipment and liquid waste under processing. Moreover, the using abrasive grain is available on a limited basis. In particular, improvement disposal of liquid waste under processing is crucial in the near future. This paper makes proposal for improvement of surface texture by utilizing dry blasting, and it conducts improvement of surface texture about martensite stainless steel (SUS420J2 In JIS), which is used in material for scale. In the previous report, it has been cleared that relationship between surface texture and wettability. In this report, adhesion of plating was measured by scratch test. As a result, it was cleared that availability of adhesion evaluation by utilizing wettability.
Grinding Characteristics of Boron Doped Diamond Grits Grinding Wheel
Authors: Iwai Manabu , Nakagawa Kiyotaka , Uematsu Tetsutaro , Takeuchi Keizo , Suzuki Kiyoshi
Published: March 2009

Metal and resin bonded diamond wheels were trial manufactured from boron doped
diamond grits possessing electrical conductivity and high oxidation temperature. From the results of
the investigation on the electro-discharge truing performance, a high truing efficiency along with
the possibility of formation of cutting edges on the grits was confirmed. According to the results of
the grinding experiment performed using this grinding wheel with flattened abrasive tips, a
remarkable improvement in the work surface roughness could be achieved. Furthermore, from the
results of the grinding test on cemented carbide and optical glass using the boron doped diamond
grits wheel, the grinding ratio was found to increase significantly, whereas the surface roughness
improved compared to a conventional diamond grits (similar friability) wheel.
Key Technologies of Image Measurement for Curve Accurate Grinding
Authors: Zhang Yong Hong , Wang L.H. , Hu De Jin
Published: March 2009

Image analysis was used to evaluate the curve grinding process. The measurement system
organization and its principle of operation were introduced. Some key technologies that influence the
system precision were also studied in details. Real-time image of work piece and wheel grinding can
be gathered while using CCD camera. For image de-noising, a kind of wavelet threshold function was
presented to calculate the new wavelet coefficients. Local threshold algorithm was used to compute
different scale threshold, another threshold is suggested when MSE is minimum. Image signals are
reconstructed through invert discrete wavelet transformation with the new wavelet coefficients. For
the purpose of increasing the measurement precision, a closed mathematical model of sub-pixel edge
detection operator was founded according to the gray moment operator’s invariant characteristics and
Tabatabai’s first three sample gray moments. An application of system validity and the comparison
results of work piece were also given. From experiments it can be said that the proposed method in
this paper is effective, and its detection precision and results are reasonable.
Analysis of the Replication Properties of Lightguiding Plate for Micro Injection Compression Molding
Authors: Shen Yung Kang , Chang H.J. , Hung L.H.
Published: March 2009

This paper presents the application of microstructure replication of lightguiding plate for
micro injection compression molding (MICM). The lightguiding plate is applied on LCD of two
inch of digital camera. Its radius of micro-structure is from 100μm to 300μm by linearity expansion.
The material of lightguiding plate is PMMA. This paper discusses the replication properties for
different process parameters by single-parameter method for micro injection compression molding.
The important process parameters of replication properties are the mold temperature, compression
distance and melt temperature in micro injection compression molding. The mold temperature is the
most significant factor of replication properties of microstructure of lightguiding plate for micro
injection compression molding.
Research on Heating Density Function and Temperature Field Mathematical Model for Milling Insert with 3D Complex Groove
Authors: Li Zhen Jia , Cheng Yao Nan , Wang Y.B. , Zhao Y.G.
Published: March 2009

Based on the milling temperature experiments and researches, we established the milling
temperature mathematical model using dimension analytic method,and the heat density function and
superficial heat density function of the flat milling insert and the waved-edge milling insert, whose
rake face is wave curve plane and created by the authors using the diathermanous theory. We
describe the mathematic model of the instantaneous temperature field by the theory of the finite
moving planar sources of heat. At last, a program was done to calculate the heat density function
and the milling temperature field. According to the calculated results and plotted graph, it is proven
that the highest temperature is not on the knifepoint and host edge, in fact, it is offset from the host
edge a certain space. So we can make the conclusion that the waved-edge milling insert’s cutting
capability is higher than the flat milling insert’s which is consistent with the experimental result.
All the studies above are the foundation for accurately describing the 3-D temperature field and
optimizing groove.
Modeling of Micro-Positioning System Using Direct Mapping and Polynomial Fit for Precision Grinding Process Control
Authors: Tse S. , Gao Y.
Published: March 2009

For micro-positioning systems using piezoelectric actuators for precision grinding process
control, sinusoidal command signals will be used and will give additional problems in comparison
with the commonly used step signals due to the hysteresis effects, which require a good modeling
approach. In order to avoid the discontinuity problem in obtaining the values of the piezoelectric
constant, a new approach of direct mapping with polynomial fit is proposed. Theoretical and
experimental studies are conducted and comparative studies are made. Compared with the single
polynomial approach, the proposed method of direct mapping with polynomial fit is able to reduce the
modeling error to 12.5%, which is 6.5% lower, and the problems in obtaining the values of the
piezoelectric constant are avoided. The proposed approach is shown advantageous. Further studies
are necessary to significantly reduce the modeling error.
Structural and Tissue Reaction Properties of Novel Hydroxyapatite Ceramics with Unidirectional Pores
Authors: Suetsugu Yasushi , Hotta Yuji , Iwasashi Masashi , Sakane Masataka , Kikuchi Masanori , Ikoma Toshiyuki , Higaki Tatsuhiko , Ochiai Naoyuki , Tanaka M.
Published: March 2009

Porous ceramics of hydroxyapatite was fabricated utilizing the crystal growth of thin ice columns parallel to one another in gelatin gel containing hydroxyapatite nanoparticles. The obtained ceramics possessed unidirectional pore channels with a porosity of around 75% and showed compressive strength of up to 13.1 MPa. As control materials, porous hydroxyapatite ceramics with a directionless pore structure were also fabricated by isotropic freezing and compared with the unidirectional samples regarding compressive strength and tissue reaction in vivo. Although the porosity and pore size distribution were similar, the compressive strength and new bone formation ability of the unidirectional samples were significantly greater than those of the random structured porous ceramics.
Setting Behaviors and Ciprofloxacin Hydrochloride Sustained Release of CSH-TCP Binary Cement
Authors: Zhang Dan , Cheng Qiang , Li Hui
Published: March 2009

Calcium sulphate hemihydrate/α-tricalcium phosphate (CSH-TCP) cement are promising
bone replacement materials with controllable-degradation rate and setting time and excellent
delivery matrix for sustained release. In the present study, setting behaviors of binary bone cement
composed of α-TCP and CSH and release of ciprofloxacin from this cement were investigated in
vitro. XRD and SEM results demonstrated that the setting products of CSH-TCP cement were
calcium sulphate dihydrate with pillar morphology and hydroxyapatite with needle morphology.
Only 20% ciprofloxacin was released from CSH-TCP cement in 7 days in vitro. Fibers of
hydroxyapatite enhanced strength of binary cement through fiber-reinforce mechanism. At initial
stage (less than 100 hours), the release of ciprofloxacin from CSH-TCP cement was diffusion
control, and at subsequent stage the release was matrix dissolution & diffusion control.
Hydroxyapatite Morphology Control by Using Hydrothermal Treatment
Authors: Kawachi Giichiro , Ishida Emile Hideki , Ioku Koji
Published: March 2009

After hydrothermal treatment of tricalcium phosphate (TCP), calcium deficient hydroxyapatite (HA) with much amount of a-surface (h00) was obtained. It was considered that c-surface of HA had larger surface tension than that of a-surface, therefore HA crystals elongated along c-axis of <001> directions. By using hydrothermal treatment, difference of surface tension was affected crystal growth of HA. The adsorption property of HA will be controlled by designing of HA morphology, because different crystal surfaces have different properties.
Study on Synthesis of Calcium Phosphate Biomaterials Containing SMB
Authors: Li M.H. , Qu Shu Xin , Shen R. , Yao N. , Ren P.D. , Weng Jie
Published: March 2009

Calcium phosphate (CaP) biomaterials containing Chinese medicine, Danshen (Salvia
Miltiorrhiza Bunge, SMB), have been synthesized in our previous study via the wet chemical
method. However, CaP biomaterials were generally synthesized in the alkaline solution. The
purpose of the present study was to investigate the effect of pH on SMB and the influence of SMB
on the synthesis of CaP biomaterials. The SMB solutions of different pH from 5.0 to 10.0, were
scanned with the UV-VIS spectrophotometer (UV-VIS) in the wavelength ranged from 200.00 to
400.00 nm. CaP biomaterials containing SMB were synthesized from (NH4)2HPO4, Ca(NO3)2,
NH4OH and SMB. The filtrates of the wet synthesis of CaP biomaterials containing SMB were
measured by UV-VIS. The synthesized CaP biomaterials containing SMB were characterized by the
X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The results showed
that the maximum absorption peak appeared at 281.00 nm for solutions of pH 5.0, 6.0 and 7.0.
Although there were a new absorption peaks as the pH were 8.0 and 9.0, the absorption curves of
SMB became similar to that of SMB as pH at 7.0 after the pH were readjusted to 7.0. The
absorption peak appeared an Einstein shift to 347.00 nm at pH 10.0, which did not return to 281.00
nm when the pH of SMB solution was readjusted to 7.0. The absorption peak of filtrates containing
SMB of CaP biomaterials reaction system was still at 281.00 nm when their pH was 7.0 and 8.0.
Moreover, SMB had no obvious effect on the phase component and functional groups of products.
Hence, it could be predicted that calcium phosphate biomaterials containing SMB, such as DCPD
and TCP containing SMB, which could be prepared at the pH ranged from 5.0 to 9.0.
Attenuation of Osteoclastic Activity Induced by Zinc-Containing Tricalcium Phosphate
Authors: Yamada Yasutaka , Ito Atsuo , Kojima Hiroko , Sakane Masataka , Miyakawa Shumpei , Uemura Toshimasa , LeGeros Racquel Z.
Published: March 2009

Osteoclasts isolated from rabbits were cultured on zinc-containing tricalcium phosphate (ZnTCP) disks with zinc contents of 0.316 and 0.633 wt%, and on β-tricalcium phosphate (TCP) disks with nearly identical porosities, grain sizes and surface roughnesses. ZnTCPs directly suppressed the resorption activity of mature osteoclasts by enhancing apoptosis. We hypothesized that resorbing osteoclasts attached to ZnTCP locally accumulate zinc ions within the space defined by the clear zone during resorption, which in turn leads to apoptosis induction, even though the change in chemical composition of the culture medium is very small.
In vitro Investigation of Mesenchymal Stem Cells with Nanophase PLGA/HA Composite
Authors: Feng Jie , Zheng Qiang , Shi Zhong Li , Jiang Hong Liang , Yan Wei Qi
Published: March 2009

Bone grafts have been used to fill bone defects caused by disease or trauma. The amount of
autografts is limited and allogenic bone grafts may transmit diseases and cause immune responses.
Numerous materials have been proposed and used as scaffolds for bone tissue reconstruction. In this
study, we tested nanophase PLGA/HA composite with mesenchymal stem cells in vitro to examine
its biological response and cellular activity. The nanophase composite was compared to
conventional polystyrene on cytocompatibility by cell attachment, proliferation, alkaline
phosphotase activity test and scanning electron microscopy (SEM) analysis. The results
demonstrated that human mesenchymal cells showed more cell attachment and higher cell
proliferation rate when growing on nanophase PLGA/HA composite than those growing on
polystyrene alone. And the composite also promoted MSC cells differentiate to osteoblast cells as
compared with control. It was suggested that the combination of bone marrow mesenchymal cells
with artificial materials or differentiation factors may enhance bone formation and regeneration,
nanophase PLGA/HA composite might therefore be a promising scaffold material for bone tissue
substitute in clinical application.
Molecular and Crystal Structure Characterization of Calcium-Deficient Apatite
Authors: Zhou Hong Hui , Li Hui , Guo Ling Hong
Published: March 2009

Calcium-deficient hydroxylapatite (CDHA) powders with Ca/P ratios from1.5 to
1.67 were synthesized by wet-chemical method. Rietveld structure refinement was performed
on the X-ray diffraction data and Fourier transform infrared spectroscopy was used to
characterize molecular and crystal structure of CDHA. With the decrease of Ca/P ratio, the
crystallite size and crystallinity decreased, but the acid phosphate content and amount of
vacancies in hydroxyapatite hexagonal structure increased. The disorder of CDHA structure
increase indicated calcium-deficiency and HPO4 replacement resulted in disorder of crystal in
apatite structure. The more calcium is deficient, the more disorder or imperfect in CDHA
structure
Kinetics of the Phase Transformation of Non-HIPed Zirconia Femoral Heads
Authors: Ikeda Junji , Pezzotti Giuseppe , Iwamoto Mikio , Ueno Masaru
Published: March 2009

The kinetics of tetragonal-to-monoclinic phase transformation (t→m transformation) in the
earlier generation zirconia femoral heads was evaluated by X-ray diffractometry, laser microscopy and
Raman microprobe spectroscopy. From previous results of hip-simulator study, it was confirmed that
phase transformation on the surface of zirconia femoral heads had little influence on wear rate of
UHMWPE sockets, and in some zirconia femoral heads, only a slight increase in monoclinic fraction
was observed during hip-simulator test. In this study, we suggest that the models of phase transformation
progress during tests in hip-simulator and aging tests are different based on both laser microscopic and
Raman/fluorescence spectroscopic observation. Besides this finding, this study shows that Raman
spectroscopy is a useful technique for the evaluation of the kinetics of phase transformation in femoral
heads after both in vitro and in vivo environmental exposure.
Bio-Tribological Properties of Bulk Metallic Glasses Sliding Against Si3N4
Authors: Kong Jian , Xiong Dang Sheng , Li Jian Liang , Yuan Qun Xing
Published: March 2009

Metallic biomaterials are used as bone plate, dental implant, wire, electrode, and so on. For the
purpose of providing the medical services with higher quality, the frictional and wear behavior of
Cu47Ti34Zr11Ni8, (Cu47Ti34Zr11Ni8)99Si, Zr41Ti14Cu12.5Ni10Be22.5 and Zr57Nb5Cu15.4Ni12.6Al10 bulk metallic
glasses (BMG) against ceramic ( Si3N4) at room temperature under dry sliding and lubrication of fresh
plasma, distilled water, and physiological saline conditions were investigated on a pin-on-disc testing
machine. Under identical sliding condition, the steady state friction coefficients of BMGs were observed
with values ranging from 0.6 to 0.9 under dry sliding, 0.5 to 0.8 under lubrication with distilled water, 0.5
to 0.7 under lubrication with physiological saline, and 0.3 to 0.7 under lubrication with fresh plasma,
respectively. Wear rates of BMGs indicated significant difference that the Cu-based metallic glasses
exhibited higher wear resistance than that of Zr-based glasses. The surface tracks indicated the existence
of viscous flow and the material transfer occurred from BMG rod to the ceramic disc. Since tribological
properties are not intrinsic properties, those results demonstrated the influences of the environment and
the characteristics of BMGs on the frictional behaviors, and furthermore indicated that BMGs may be
one of the promising biomaterials in the future.
Medial Placement of a Cementless Acetabular Component in a Modern Alumina-on-Alumina THA
Authors: Yoo Jeong Joon , Kim Hee Joong , Kim Young Min , Yoon Kang Sup , Koo Kyung Hoi , Nam Kwang Woo , Kim Yong Lae
Published: March 2009

Medial placement of a cementless acetabular component into or beyond the medial wall of a shallow, dysplastic acetabulum is a technique to enhance its coverage during difficult total hip arthroplasty (THA). Dysplastic hips almost always need small size of acetabular component, so an accelerated polyethylene wear can occur when a conventional bearing surface is used. Modern alumina-on-alumina couplings can be an alternative for these patients. We evaluated the clinical results of 43 medially placed cementless acetabular components (PLASMACUP®SC) incorporating a modern alumina bearing surface (BIOLOX® forte). Acetabular components were inserted medially beyond the ilioischial line and, therefore, beyond the level of the cortical bone of the cotyloid notch, and followed up for more than 5 years (range, 60 – 93 months). In 14 hips, the medial acetabular wall was perforated purposefully and the medial aspect of the cup was placed beyond both the ilioischial and the iliopubic line on radiographs. The mean Harris hip score improved from 55.3 points preoperatively to 94.5 points postoperatively. Postoperatively, the hip center migrated 12.1 mm medially and 1.5 mm inferiorly. The average amount of cup protrusion beyond the ilioischial and the iliopubic line was 3.1 mm and 1.9 mm, respectively. The average superolateral coverage of the cup was 98.5 percent. During follow-up, no osteolysis or loosening of acetabular components was observed and no revision was required. Medial placement of a cementless acetabular component into or beyond the medial acetabular wall offers predictable clinical results and durable fixation in modern alumina-on-alumina THA.
Cell Proliferation on Titania Layer with In Vitro Apatite Forming Ability
Authors: Yabe S. , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi , Yoshida Y. , Suzuki K. , Kuboki T.
Published: March 2009

Titania layer was fabricated on the titanium substrates with chemical treatment with 20ml or 40ml of
hydrogen peroxide solution and subsequent heat treatment at 400°C, coded as CHT20 and CHT40, respectively.
CHT20 spontaneously deposited apatite on the surface in a simulated body fluid (SBF), while CHT40 did not.
TF-XRD patterns showed that the diffraction intensity of anatase of CHT20 was higher than that of CHT40. It
was suggested that the thicker titania layer indicated in vitro apatite forming ability. The cell proliferation of
CHT20 and CHT40 were lower than NT and HT. Since the surface of titania layers became hydrophobic after
autoclaving, we can suppose that the cell proliferation on CHT20 and CHT40 were lower than NT and HT due
to their surface hydrophobicity.
Effect of Bleaching on Dental Hard Tissues: A Raman and IR Spectroscopic Study
Authors: Wang Xiao Jie , Klocke Arndt , Mihailova Boriana , Stosch R. , Güttler B. , Bismayer Ulrich
Published: March 2009

The effect of two bleaching materials on dental enamel was studied by vibrational
spectroscopy. Human molar enamel sections parallel to the dentin-enamel junction were one-side
polished and treated with bleaching agents containing 38% hydrogen peroxide (Opalescence Xtra
Boost) or 20% carbamide peroxide (Opalescence PF 20%). Then the crystalline structure and
molecular inclusions of the bleached samples were analyzed by Raman scattering and attenuated
total reflectance infrared spectroscopy. No spectral difference was observed between the
unbleached enamel and that bleached with the two different agents, which indicates no significant
occurrence of structural or chemical changes in enamel apatite due to bleaching.
Influence of Hydrothermal Reaction Temperature and pH on Phase Stability of Hydroxyapatite
Authors: Park Sun Hyo , Ryu In Young , Kim Dae Joon , Han Jung Suk , Lee Myung Hyun
Published: March 2009

The effect of hydrothermal reaction temperature and pH on crystallite size, phase stability, and sintered density of hydroxyapatite (HAp) has been investigated. The crystallite size increased with the increase in temperature but was not significantly affected by pH. The decomposition of HAp into tricalcium phosphate was observed at 1250°C and the extent of decomposition decreased with increase in pH. The influence of temperature and pH on the crystallite size and the decomposition was related to the decrease in solubility of Ca2+. The phase stability of HAp, prepared hydrothermally, in HAp/zirconia composites was higher than that of commercial HAp due to its high sintered density.
Electrospun Poly(L-lacticacid)/Nano-Hydroxyapatite Hybrid Nanofibers and Their Potential in Dental Tissue Engineering
Authors: Xu M. M. , Mei Fang , Li Dan , Yang Xiao Ping , Sui Gang , Deng Xu Liang , Hu X. Y.
Published: March 2009

Efficacy of poly(L-lactic acid) (PLLA)/nano-hydroxyapatite(HA) hybrid nanofibrous scaffolds for dental tissue engineering is described and their performance on normal cells with MG-63 is compared as well in this study. Perfectly PLLA/HA fibrous scaffolds were fabricated by an electrospinning process under optimal condition. Cell culcure and adenovirus encoding green fluorenscent protein technique were used to study the morphology of cells grown on the scaffolds. The results show that the growth of DPSCs and PCs is well observed attached to the PLLA/HA fibers, as well as MG-63, which indicate that the nanofibrous PLLA/HA scaffold could be used as a potential cell carrier in dental tissue engineering.
Investigation of a Collagen-Chitosan-Hydroxyapatite System for Novel Bone Substitutes
Authors: Wang Xiao Liang , Li Xu Dong , Wang Xiao Min , Lu Jian , Zhao Hui Chuan , Zhang Xing Dong , Gu Zhong Wei
Published: March 2009

Collagen (Col) and chitosan (Chi) are both natural polymers and have received extensive investigation in recent years in the field of tissue engineering, but there are few reports on the introduction of hydroxyapatite (HA) into the Col-Ch system. In this study, based on the miscibility of these two polymers under proper condition, hydroxyapatite (HA) was synthesis in the Col-Chi system by in-situ co-precipitate method to give rise to a novel nanocomposite. The structural characterization of such Col-Ch-HA nano-materials was carried out by using FT-IR, XRD, SEM and TGA analyses with main components and Col-Chi samples used for comparison. It was found that there exist interactions between Col and Chi molecules. The nucleation and growth of inorganic phase occurs in the Col-Chi system and final products are uniform dispersion of nano-sized HA in the Col-Chi network without obvious phase separation. This novel nanocomposite would be a promising material for bone tissue engineering.
A Novel Way of Dispersing Fine Ceramic Particles in PLGA Matrix
Authors: Yang Z. , Thian E.S. , Best Serena , Cameron Ruth
Published: March 2009

α-tricalcium phosphate (α-TCP) was prepared by a wet precipitation reaction between calcium hydroxide and orthophosphoric acid solutions. The as-synthesised powder was then characterised using a Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectroscope (EDS), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscope (FTIR). Analyses revealed that a phase-pure powder with a Ca/P ratio of 1.5 was produced. In addition, nanosized α-TCP particles of diameter ~ 70 nm were agglomerated to form larger particles of 10μm in diameter. It was found that by the combination of attritor milling and solution evaporation, the agglomerates of α-TCP nanoparticles could be broken down, and distributed evenly within the poly(D,L-lactic-co-glycolic acid) (PLGA) matrix. Thus, a α-TCP/PLGA nanocomposite was successfully produced by a modified solution evaporation method at room temperature followed by hot pressing at 150 °C. The achievable ceramic loading was approximately 38 wt.%, which was confirmed by thermal gravimetric analysis (TGA).
In Vitro Dissolution of Amorphous Calcium Phosphate (ACP) Increased the Wear Particle Generation of Plasma-Sprayed HA Coatings
Authors: Tong Wei Dong , Li Pan Jian
Published: March 2009

Hydroxyapatite (HA) coated total hip joint device has caused concerns of generating wear particles after long-term implantation. We designed a pin-on-disk (POD) test to examine the morphological changes and wear particle generation of plasma sprayed HA coating in vitro. HA coatings were immersed in supplemented α-calf bovine serum for 48 hours. Serum soaked HA coating exhibited significant amount of weight loss due to dissolution of amorphous calcium phosphate (ACP). POD test demonstrated the serum soaked HA coatings presented many micronsized particles on the surface while the as-received HA coatings maintained good integrity. The generation of wear particles of the serum soaked HA coatings is related to the reduction of the cohesion/adhesion of HA coatings due to the preferential dissolution of ACP.
The Study of Surface Energy, Electrical Properties and Platelet Adhesion Behavior of a-C/a-CN Films Synthesized by PIII-D
Authors: Wen Feng , Huang Nan , Sun Hong , Zhao An Sha , Wang Jin , Li Yu Jie , Wang Ze Wen
Published: March 2009

Amorphous carbon (a-C) and carbon nitrogen (a-CN) films were synthesized using plasma immersion ion implantation and deposition (PIII-D) under different N2 flow at room temperature (R.T.). Lifshitz-van der Waals/acid-base approach (LW-AB) was introduced in order to study films’ surface energy deeply. The results showed that the capability of the surface of the film on receive electron changed with N2 flow, which effected platelet adhesion of film strongly. Hall effects tests were employed to characterize the electrical properties of the films. The results showed that the as-deposited films exhibited n-type semiconductor characteristic, and carrier concentration of the films decreased with N2 flow increasing. Raman spectra with 514nm laser-source were employed to analyze the structural of the films.
In Vitro Apatite-Forming Ability of Titania Films Depends on Their Substrates
Authors: Shozui T. , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi
Published: March 2009

Titania films were coated by means of sol-gel method on various substrates such as
titanium, titanium alloy, silicon wafer, stainless-steel, alumina, and glass slide where they coded as
C5Ti, C5Ti6Al4V, C5Si, C5SUS, C5Al2O3 and C5GS, respectively. Their in vitro apatite-forming
ability was examined with the Kokubo’s simulated body fluid (SBF; pH 7.4, 36.5°C). C5Ti,
C5Ti6Al4V and C5Si deposited apatite particles on their surface within 7 days, whereas, C5SUS,
C5Al2O3 and C5GS did not. These results implied that the in vitro apatite-forming ability of the
titania films indirectly depended on the chemical or physical properties of the substrates.
The Formation of an Apatite Coating on Y-TZP Zirconia Ceramics
Authors: Beranič Klopčič Sabina , Pribošič Irena , Kosmač Tomaž
Published: March 2009

Apatite-forming ability on a zirconia surface was investigated using a conventional
SBF (c-SBF), a 1.4 SBF (concentration of ions 1.4 times higher than in SBF) and a
supersaturated Ca/P solution. After 5 days a small amount of hydroxyapatite was formed on
the zirconia surface in the 1.4 SBF, whereas no apatite was detected on the zirconia surface
exposed to the c-SBF for 5 days. In the supersaturated Ca/P solution some isolated clusters of
hydroxyapatite were observed on the zirconia surface after only 2 hours, and after 27 hours of
immersion time, the zirconia surface was homogeneously covered with hydroxyapatite. Some
of the covered zirconia substrates were heat treated at 1050°C for 1 hour. The thermally
treated and untreated samples were immersed in SBF for 7 and 14 days. The results confirmed
that additional hydroxyapatite was formed in the SBF in both cases, regardless of whether the
covered zirconia substrate was pre-heated or not.
Calcium Phosphate Biomaterials Composite Device: In-Vitro and In-Vivo Investigation
Authors: Tofighi Aliassghar , Sutaria M.
Published: March 2009

Low crystalline apatite (LCA) and calcium phosphate cements (CPC) based on amorphous calcium phosphate and dicalcium phosphate dihydrate (1 to 1 ratio) were combined with bioresorbable PLGA copolymer (0 to 20 wt.%) for preparation of solid-formed devices. A pilot manufacturing based on powder processing techniques using isostatic pressure (44,000 psig) was conducted. Processing parameters such as isostatic pressure, temperature, times and device dimension were varied to achieve appropriate mechanical properties comparable to that of allograft bone dowel used as a gold standard in clinical application. The solid-form devices were characterized for physico-chemical and mechanical performance, as well as subjected to an in-vitro wet environment incubation at body temperature (37°C). Fluid diffusion was investigated to evaluate the fluid absorption (through microporosity) and the compressive strength of wet devices vs. incubation time (up to 30 days) was also studied. The shear strength and compressive strength of pure LCA dowels was respectively 26 and 122 MPa, which corresponds to a process densification of about 30%. The compressive strength was dramatically improved with addition of various amounts of copolymer. The maximum compressive strength of 180 MPa was obtained for dowels containing 10 wt.% copolymer. Calcium phosphate composite also increased the shear strength to about 42 MPa. These mechanical performances were significantly higher than that of allograft bone dowel (MD-II™), reported about 10 MPa. A pilot sheep interbody fusion of lumbar spine (L3/L4 and L4/L5) demonstrates mechanical integrity and intervertebral fusion at 6 months. LCA was found to be the most suitable CaP material because of its biocompatibility, chemical composition, nano-structure and high specific surface area that exhibits in-vivo biointegrity and cell mediated process.
Chitosan-Crystallized Apatite Composites for Bone Cements: Mechanical Strength and Setting Behavior
Authors: Rattanachan Sirirat T. , Lorpayoon Charussri , Bunpayun Piyanan
Published: March 2009

Crystallized apatite behaved to plaster of Paris was prepared by the chemical method.
Apatite powder was mixed with chitosan. In this study, it was also studied the effect of HA seed and
sodium hydrogen phosphate as an additive on their mechanical strength, compared with the normal
calcium phosphate cements. Setting time of paste cements was determined using Gillmore method.
Phases of cement obtained from a crushed cylinder were analyzed using XRD analysis. From the
results, chitosan was effective both in increasing mechanical properties and accelerating hardening of
the normal bone cements. Nevertheless, the compressive strength of chitosan-crystallized apatite
composites was not significantly improved as compared to the controlled one. In addition, it was
found that the mechanical strength of the cements decreased when increasing the concentration of HA
seed and an additive.
Biomimetic Bone Graft with Higher Bioactivity
Authors: Martinetti Roberta , Dolcini L. , Merello Luisia , Scaglione Silvia , Quarto Rodolfo , Pressato Daniele
Published: March 2009

The use of 3D osteoconductive scaffolds provides an informative substrate serving as a physical support matrix for in vivo tissue regeneration. In the last few years the use of bioengineered 3D scaffolds has been becoming the most promising experimental approach for the regeneration of living tissues. Stem cells are typically used, in combination with 3D substrates, to promote in vivo bone regeneration and repair. For tissue engineering applications, biomaterials should therefore be able to support the functional properties of osteo-progenitor cells, giving them the optimal microenvironment to perform their physiological activity. Inorganic biomaterials are particularly relevant for bone regeneration; calcium phosphate ceramics have in fact been shown to strongly interact with bone tissue. The aim of the present work was to evaluate two different scaffolds with a defined design and different composition developed to guide/promote tissue repair.
Bone Ingrowth Into Porous Bioactive Titanium Implant for Load-Bearing Use: Experimental Study Using a Novel Canine Anterior Interbody Fusion Model
Authors: Takemoto Mitsuru , Fujibayashi Shunsuke , Neo Masashi , So Kazutaka , Akiyama Norihiro , Matsushita Tomiharu , Kokubo Tadashi , Nakamura Takashi
Published: March 2009

We have developed a porous titanium implant sintered with spacer particles (porosity =
50 %, average pore size ± standard deviation = 303 ± 152 !m, yield compression strength = 100MPa).
This porous titanium was successfully treated with chemical and thermal treatment that gives a
bioactive micro-porous titania layer on the titanium surface, and it is expected as effective biomaterial
for biological fixation on load bearing condition. In this study, ten adult female beagle dogs
underwent anterior lumbar interbody fusion at L6-7 using either BT-implant or non-treated implant
(NT-implant), then followed by posterior interspinous wiring and facet screw fixation. The
radiographic evaluations were performed 1, 2 and 3 months postoperatively using X-ray fluoroscopy.
Animals were sacrificed after 3 months postoperatively, and fusion status was evaluated by manual
palpation. Histological evaluation was also performed. Both histological and radiological evaluation
revealed that interbody fusion was achieved in 5 of 5 dogs (100%) in BT-group and 3 of 5 dogs (60%)
in NT-group. In BT implants, we could observe a large amount of new bone formation from periphery
to the center of the implant, whereas in NT implants, fibrous tissue formation was still observed even
in the implants with successful fusion. The results of this study indicate that porous bioactive titanium
implant will represent a new osteoconductive biomaterial with improved fusion characteristics.
Development of Failure Tolerant Multi-Layer Silicon Nitride Ceramics: Review from Macro to Micro Layered Structures
Authors: Kübler Jakob , Blugan Gurdial , Lugovy M. , Slyunyayev V. , Orlovskaya N. , Dobedoe Richard
Published: March 2009

Recent developments have shown that producing multi-layer ceramic laminates with alternative layers under compressive and tensile stress can lead to significant improvements in toughness at a low cost. However, in many cases the improvements in fracture toughness is associated with the presence of surface “edge cracks” in the compressive layers or the use of porous interfaces between the layers. At the same time such effects can limit the performance of ceramics when used in harsh environments. This review covers the development of silicon nitride based laminate structures and characterisation of these multi-layer structures. The work presents the results of macro-layered laminates with layers greater than 150 μm thickness. The apparent fracture toughness of different designs is measured and the conditions for failure tolerant effects, including crack deflection, bifurcation and edge cracking, are shown and discussed. The structural and processing limitations of the macro-layered laminates are also presented. The development of a weight function analysis as an effective design tool for developing micro-layered laminates with layers of approximately 50 μm thickness is discussed along with the apparent fracture toughness results from these micro-laminates. The failure tolerant behaviour as well as the ease of producing micro-layered laminates with a toughness of 2-3 times higher than that of silicon nitride is shown.
Monocomponent Powders and Thin Films in the Binary System SiO2–TiO2
Authors: Gartner Măriuca , Crisan M. , Predoana L. , Zaharescu Maria , Barau A. , Preda S.
Published: March 2009

In this work, we report the sol-gel alkoxide route preparation of nanostructured SiO2 and TiO2 powders as well as TiO2-SiO2 thin films obtained by dip-coating. Thermal analysis, morphology and structure were characterized for powders and correlation between preparation method and optical properties of binary materials (SiO2-TiO2) for thin films was approached. Spectroscopic Ellipsometry (SE), Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) have been used for the physical characterization of the films.
Composite Materials for Thermal Expansivity Matching and High Heat Flux Thermal Management
Authors: Kelly Anthony
Published: March 2009

A description is given of a possible solution of an important practical problem in
microelectronics, namely producing a material of thermal expansion coeffiecient to equal that of
silicon.
Fabrication of Cf/SiC Composites by Hot-Pressing
Authors: Ding Yu Sheng , Dong Shao Ming , Zhou Qing , Jiang Dong Liang
Published: March 2009

Continuous carbon fiber-reinforced silicon carbide (Cf/SiC) composite was fabricated by
hot-pressing, via liquid phase sintering. Sintering conditions strongly affect the densification process,
and therefore dominate the mechanical properties and fracture behavior. The composites under the
lower sintering temperature behaves less densified matrix and it demonstrates a relatively weak
fiber/matrix bonding allowing the longer fibers pull-out. Increasing sintering temperature could
accelerate the densified matrix and make fiber/matrix bonding stronger. In this case, the shorter fibers
pull-out was predominant fracture behavior and it could improve mechanical properties.
Perforated FRP Shear Connector for the FRP-Concrete Composite Bridge Deck
Authors: Nam Jeong Hun , Yoon Soon Jong , Ok Dong Min , Cho Sun Kyu
Published: March 2009

In recent years, the FRP-concrete composite bridge deck system has been introduced because of its light-weight and durability. The FRP-concrete composite bridge deck is composed of FRP module and concrete, and they are connected with shear connectors. In order to insure the composite action between FRP module and concrete, appropriate types of shear connector need to be installed. In this study, new type of FRP shear connector was suggested and the experimental investigations are conducted based on the studies of Perfobond. In the experimental study, the push-out test was conducted and the load carrying mechanism was analyzed including the friction effect of sand coating. Considering the load carrying mechanism of perforated shear connector under shear force, the empirical equation for the prediction of shear strength of perforated FRP shear connector was suggested.
Development and Evaluation of Mechanical Properties for Kenaf Fibers/PLA Composites
Authors: Ben Goichi , Kihara Yuichi
Published: March 2009

A new type of composite used biodegradable resins and natural fibers is now being
developed and this new type of composites is designated as a green composite. This paper
presents a fabrication method and mechanical properties of the green composite used Kenaf fibers
as the reinforcement and PLA as the matrix. In order to obtain the higher tensile strength, various
kind of surface treatments were executed on the Kenaf fiber and some parameters were changed
during the process of fabrication. Then, these effects on the strength of green composite are also
reported.
Fabrication of Porous Silicon Nitride with High Porosity
Authors: Shan Shao Yun , Yang Jian Feng , Gao Ji Qiang , Zhang Wen Hui , Jin Zhi Hao , Janßen Rolf , Ohji Tatsuki
Published: March 2009

In this study, porous Si3N4 ceramics were fabricated by carbothermal reduction reaction between silicon dioxide and carbon. The influences of different starting powders and sintering additives on microstructure and mechanical properties were investigated. XRD analysis demonstrated the formation of single-phase β-Si3N4 except for glass phase and minor of α-Si3N4 phase. SEM analysis showed that the resultant porous Si3N4 ceramics occupied fine microstructure and uniform pore structure. The samples with fine starting powder showed fine, high aspect ratio of β-Si3N4 grains and good mechanical properties. The addition of Al2O3 accelerated the densification of porous Si3N4 ceramics. With an increasing in the sintering additive content, the porosity decreased, the flexural strength increased.
Fabrication of Lightweight SiC Space Mirror
Authors: Chen Yu Feng , Wang Hua , Tang Jie , Liu Hai Lin , Chen Shu Guang , Fan Qi Sheng
Published: March 2009

Silicon carbide ceramic has many attributes including high strength and stiffness, low thermal expansion coefficient, high thermal conductivity, low density and good resistant for radiation of space particles. These attributes make SiC ceramic becoming the third generation space mirror material. This paper describes the fabrication of lightweight SiC mirror blanks. By reducing the shrinkage of green body and controlling the drying conditions, lightweight SiC mirror blank with a diameter of 612mm has been prepared by using gelcasting process. The forming green body is infiltrated with liquid silicon at the temperature of 1600°C, then a CVD SiC layer is coated on the surface of SiC mirror blank. After grinding and polishing, the mirror shows good optical properties.
Microstructural Evolution and Mechanical Properties in Yb2O3–Fluxed Silicon Nitride Ceramics
Authors: Guo Gang Feng , Yang Xiao Zhan , Li Jian Bao , Lin Hong , Liang Long , He Ming Sheng , Tong Xu Guang
Published: March 2009

Silicon nitride ceramics were fabricated with Yb2O3 as the sintering additive. The effects of the amount of Yb2O3 on the microstructure and the mechanical properties such as the flexural strength and the fracture toughness were investigated. Almost fully densified Si3N4 was obtained when only 4 wt% Yb2O3 was added. Both the flexural strength and the fracture toughness increased steadily with the Yb2O3 content. The transgranular fracture mode was observed in the specimen containing 4 wt% Yb2O3, however, the intergranular fracture mode was observed in the specimen containing 10 wt% Yb2O3.
Electric and Damping Properties of PU Based IPNs-BaTiO3 Nanocomposites
Authors: Tang Dong Yan , Jin Zheng , Qiang Liang Sheng
Published: March 2009

(PU/UP IPNs)-BaTiO3 nanocomposites with different amounts of BaTiO3 nanopowder are
prepared and polarized. The ferroelectric and dielectric properties are detected and the relationship
between electric properties and damping properties are discussed in detail. Results indicate that the
synergistic effects can be created successfully by elastic damping of polymer, frictional damping of
BaTiO3, and piezoelectric damping of nanocomposites after poling. The nanocomposites increase the
damping property evidently and sustain mostly ferroelectric and dielectric characters of inorganic phase.
The introduction of BaTiO3 into IPNs decreases the resistivity, and this has advantages to enlarge the
damping loss factor (tanδ).
SAXS Characterization of Nanochannels in Polymer-Derived SiC Fibers
Authors: Chu Zeng Yong , He Rong An , Li Xiao Dong , Cheng Hai Feng , Wang Jun
Published: March 2009

In the preparation of polymer-derived SiC fibers, nanochannels are believed to be formed in the
early pyrolysis stages due to loss of large volumes of pyrolysis gases. In this paper, small angle X-ray
scattering (SAXS) was applied to the characterization and calculation of nanochannels in partiallypyrolyzed
SiC fibers. The SAXS measurements showed that nanochannels with a radius of 1.0-20 nm
were formed for fibers heat-treated at 973K and 1173K. But their distributions were not continuous and at
lower part of the distribution, a peak value was observed at about 1.2nm. This means if the nanochannels
are finely controlled, the partially-pyrolyzed SiC fibers have great potential application in the fields of
hydrogen storage, gas separation, and so on.