bluuebunny/crossref_metadata_2025 huggingface dataset:
Rigid-Plastic Finite Element Simulation of Deformation Mechanisms during Rolling of Complex Sheets Containing an Inclusion
Authors: Chen Dyi Cheng
Published: March 2009

Using rigid-plastic finite element DEFORMTM 2D software, this study simulates the plastic deformation of complex sheets at the roll gap during the sheet rolling process. Specifically, the study addresses the deformation of complex sheets containing inclusion defects. Under various rolling conditions, the present numerical analysis investigates the damage factor distributions, the void length at the front and rear of the inclusion, the deformation mechanisms, and the stress-strain distributions around the inclusion. The relative influences of the thickness reduction, the roll radii, and the friction factors on the void length at the front and rear of the inclusion, respectively, are systematically examined. Additionally, the correlation between the front and rear void lengths and a series of damage factors is explored. The simulation results appear to verify the suitability of the DEFORMTM 2D software for modeling the rolling of complex sheets containing inclusions.
Warpage Analysis of FBGA (Fine Ball Grid Array) Package by the Altered EMC (Epoxy Molding Compound) Filler Contents
Authors: Park Yong Tae , Whang Yoo Kyoung , Hong Joon Ki , Byeon Kwang Yoo
Published: March 2009

In a semiconductor packaging process, the warpage greatly has influenced the reliability of the package as well as the workability. The strip warpage in FBGA package result from the structure of constitutes and the thermal mismatch by the mechanical or thermal properties such as CTE (Coefficient of Thermal Expansion) and Modulus of EMC, substrate, chip and adhesive materials. Therefore, the optimization of material properties and the package structure design has been needed by the numerical analysis. EMC used as one of the package constituents has a decisive effect on the trend of warpage, and the filler content is dominant in the EMC property. In this research, firstly the effect of the filler contents is evaluated in the warpage of FBGA package and the numerical analysis is performed with the high temperature – material properties to deal with the warpage under the actual measurement value.
A Simplified Method to Estimate Elastic-Plastic Fracture Mechanics Parameters under Combined Primary and Secondary Stresses
Authors: Kim Yun Jae , Oh Chang Gyun , Kim Jong Sung , Jin Tae Eun
Published: March 2009

Detailed two- and three-dimensional finite element analyses are performed to develop an engineering method to estimate elastic-plastic J for cracked structures under combined primary and secondary stresses, based on the V-factor. Extensive analyses with a wide range of geometry and load combination are considered. The results suggest important factors affecting the value of the V-factor. The most important one is the load magnitude, parameterized by the proximity of plastic yielding. The second one is the relative magnitude of the secondary stress to the primary stress. Although the effect of material, in particular materials with Lüders strain seems to be present, such an effect could be neglected, compared to those of the above two parameters. Based on the present results, an engineering method to estimate J for combined primary and secondary stress can be proposed using
bilinear equations in terms of the above two parameters.
Critical Load between Sea Ice and Sea Structure
Authors: Fan Wen Xin , Song Wei Dong , Ning Jian Guo
Published: March 2009

The main objective of this paper is to propose the buckling equations of the sea sheets under concentrated forces. Two different cases of the acting forces are considered in this paper and the buckling equations of them are deprived, respectively. Then, the dimensionless forms of these equations are given. Furthermore, by adopting a numerical method, two cases of different thickness of the ice sheet and different distances between sea structures are explored. On the basis of the buckling equations, the expressions of the critical load between sea ice and sea structures are obtained. Finally, the relationship between the critical load factor and the dimensionless radius are presented
Sensor Fusion Strategy in the Monitoring of Cutting Tool Wear
Authors: Mahardika Muslim , Taha Zahari , Suharto Djoko , Mitsui Kimiyuki , Aoyama Hideki
Published: March 2009

Cutting tool wear is a major problem in machining processes. It has a great effect on the quality of a workpiece. Thus, monitoring cutting tool wear is very important in order to maintain the workpiece quality as well to reduce production rate and production time. The use of a single sensor in a monitoring system may not be accurate to detect cutting tool wear. In this paper, sensor fusion technology is introduced for monitoring cutting tool wear.
Dynamic Fracture Toughness Testing for Welding Part of Nuclear Piping Using Normalization Data Reduction Technique
Authors: Huh Yong , Kim Hyung Ick , Seok Chang Sung
Published: March 2009

In this study, we performed the static test of nuclear piping materials by the unloading compliance method and the normalization data reduction technique and obtained two fracture resistance curves (J-R curves). The two curves were similar, which proves that the normalization data reduction technique can be adopted in the static test. Then we performed the dynamic fracture toughness test for welding part of nuclear piping. The J-R curves were obtained from the dynamic test by the normalization data reduction technique and were compared to those of the static test results.
Elastic Behaviors of Stitched Multi-Axial Warp Knit Fabric Composites
Authors: Chun Heoung Jae , Kim H.W. , Byun Joon Hyung
Published: March 2009

The purposes of stitching multi-axial warp knitted fabric preform prior to the fabrication of the composite materials by resin-transfer molding technique are to improve the resistance to delamination and to increase the out-of-plane properties of the composite materials for structural integrity. The influence of the through-the-thickness stitching on the elastic properties and behaviors of the multi-axial warp knit fabric composites is studied. An analytical model based on the representative volume is proposed to predict the elastic properties of the stitched multi-axial warp knit fabric composite materials. The fiber volume ratios determined by geometric parameters set by the representative volume and elastic behaviors of the in-situ constituent materials are used for the predictions. The crucial step in the analysis is to correlate the averaged stress states in the constituents by adopting bridging matrix. The predicted results are compared with the experimental results. It is found that the predicted results are in reasonably good agreement with the experimental results.
An Analysis and Experimental Study of the Rotor Blade with Composite Material Fiber Reinforced Plastics
Authors: Son C.Y. , Byun H.I. , Kim K.H. , Choi J.K. , Shin J.Y.
Published: March 2009

In these days, large-scale wind turbines are being made of the Glass Fiber Reinforced Plastic (hereinafter F.R.P). Some reinforcement stiffeners such as carbon fiber and polyamide (Kevlar) are not economical for the wind turbine. In addition, the steel or aluminum alloy, featuring heavy weight and metallic fatigue load, is not suitable for global use, except very small-scale wind turbines. In this study, we manufactured a 10kW-grade small Rotor Blade with the F. R. P featuring high
stiffness and good dynamic behavior characteristic, and carried out experiments for understanding the bending behavior characteristic of the fatigue load and bending load. And, we examined the experiment results through the Finite Element Method. We compared the experiment results and FEM analysis outputs using the commercial ANSYS FEM program.
Flux Waveform Control in Electrical Steels Using Digital Feedback Technique
Authors: Jahidin Aisyah Hartini , Hamzah Fitri Pearlratna , Wan Mahadi Wan Nor Liza
Published: March 2009

There are increasing calls for more accurate power loss measurements in electrical steels. This paper presents the flux controlling technique in electrical steels using digital feedback technique. The various parameters that affect the measuring efficiency have also been analyzed. Digital feedback technique is used since it has the advantages of good reproducibility of the waveform due to ease of calibration and its stability with respect to time as well as reduces human error. Furthermore, it has no oscillation of the control system compared to the analog feedback technique. This technique was designed by using Simulink, MATLAB R12, Version 6.0. The digital feedback circuitry, which has been designed, is proved to be successful where the output waveform is a sinusoidal waveform of 50Hz. It is shown that the harmonic component increases as the distortion factor increases. It also indicates that the average distortion factor for nth harmonic to the distorted waveform is typically less than 1.5 and meaningful measurements can be performed.
Effects of Re Alloying on Mechanical Properties of In-Situ Composites with Base Composition of Nb-18Si-2HfC
Authors: Wang Sheng Wu , Tabaru Tatsuo , Hirai Hisatoshi , Ueno Hideto
Published: March 2009

Nb-base in-situ composites with the base composition of Nb-18Si-2HfC were prepared by conventional arc-melting. Their microstructures and mechanical properties, such as high-temperature strength and room temperature fracture toughness, were investigated to elucidate the effects of Re alloying. The in-situ composites predominantly have eutectic microstructures consisting of an Nb solid solution (NbSS) and Nb5Si3. The compressive strength increased with the increasing Re contents at 1470K and not at 1670 K. The strengthening effect observed at 1470 K is higher than that by W and Mo. Re alloying of about 2 % is valuable for improving both the high temperature strength and room temperature fracture toughness of Nb-18Si-2HfC base materials.
Posterolateral Lumbar Fusion by Tissue Engineered Bone
Authors: Yoshikawa Takafumi , Ueda Y. , Koizumi M. , Iida Jin , Miyazaki Kazuhide , Shigematsu Hideki , Satoh N. , Nonomura Akitaka , Takakura Yoshinori
Published: March 2009

Posterolumbar fusion, which involves placing a bone graft in the posterolateral portion of the spine, has been applied to patients with lumbar instability due to structural defects or regressive degeneration. However, harvesting cancellous bone from the ilium is associated with severe postoperative pain, and patients experience more pain at the harvest site than at the graft site, thus resulting in poor patient satisfaction. If a tissue engineering approach was used to produce autogenous bone ex vivo with culture techniques, spinal fusion could be performed without damaging normal tissues. In all patients, 10 to 20 mL of bone marrow fluid was collected from the ilium and cultured in MEM containing autologous serum or fetal bovine serum and an antibiotic. After two weeks in primary culture, the marrow mesenchymal cells were seeded onto porous beta-TCP block, and tissue engineered bone were fabricated as we reported previously. Decompressive laminectomy and posterolateral lumbar fusion with use of the tissue engineered bone thus obtained were then done. In all patients, the implanted artificial bone survived and bone regeneration was detected radiographically, and the clinical symptoms were improved. Short term follow-up has shown that the bone implants were effective in all of the patients. There were no adverse reactions related to implantation. The use of this tissue engineered bone makes it possible to perform osteogenetic treatment without harvesting autogenous bone, thus avoiding pain and pelvic deformity at the site of bone collection and reducing the burden on the patient.
Organ Regeneration in Porous Hydoroxyapatite
Authors: Okumura Noriko , Yoshikawa Takafumi , Nonomura Akitaka , Takakura Yoshinori
Published: March 2009

HA has a high affinity for bone as well as various tissues. In the present study, we
investigated an affinity for abdominal organs. Coralline hydroxyapatite ceramic (HA, cubic structure 4x4x4mm, Interpore 500) was used in this experiment. We made two incisions in the lower back of a 5-week-old male nude mouse, and implanted HA blocks. One was placed around the liver at the right side and another one was placed around the kidney at the left side. The organ fibrous capsule was not
removed. At 6 weeks after implantation, mice were sacrificed under overanesthesia and HA blocks were retrieved and prepared for histological analysis. In the HE stain of HA blocks around liver, liver tissue is invaded into the HA pore areas. Hepatocyte proliferation in trabecular pattern was seen in contact with the surfaces of many HA pores. Within some pores, hepatic lobular pattern, Glisson sheath or central vein could be detected. In the HA around kidney, renal tissue was observed in many
pores. The pore areas of HA were fullfilled with grumerulus and urinary tube tissues. In contact with the surfaces of some HA blocks, the tissue invasion of pancreas and spleen tissue were recognized. These results indicate that porous HA has a high affinity for the celiac organs, and has a stimulatory effect on celiac organ regeneration. Especially, concerning the regeneration of kidney, it has not been
reported yet, so this report is very interesting. HA is also very useful as a scaffold of the organ regeneration.
Surface Structure Design and Characterization of Bioabsorbable and Functionally Graded Apatites Originated from Bovine Bone
Authors: Akazawa Toshiyuki , Murata Masaru , Tazaki Junichi , Nakamura Katsuo , Kanno Tohru , Kobayashi Masayoshi , Itabashi Kohji , Arisue Makoto
Published: March 2009

Abstract. Bioabsorbable and functionally graded apatites (fg-HAp) ceramics were designed using calcined bovine bone (b-HAp) by the partial dissolution-precipitation methods. The fg-HAp ceramics with micro-pores of 10-160 nm had larger specific surface areas (30-40 m2･g-1) than the
b-HAp ceramics, although the two HAp ceramics exhibited same macro-pore sizes of 100-600 µm and porosities of 60-80 %. Surface structure of these ceramics was modified by soaking at 309.5 K for 1-90 days in a simulated body fluid (SBF). At 8 days after the soaking, microstructure of the fg-HAp changed from small grains to dense cocoon-like ones by rapid precipitation of HAp
microcrystals, while at 14 days, that of the b-HAp was porous urchin-like grains, suggesting that the fg-HAp had higher bone-bonding ability than the b-HAp.
Bimodal Porous β-TCP Ceramics and its Dissolution in Phosphate Buffer Saline
Authors: Zhang Yin , Yokogawa Yoshiyuki , Kameyama Tetsuya
Published: March 2009

Two kinds of tri-calcium phosphate ceramics, β-TCP, which have the same macrostructure and microstructure, but different special surface area and particle size, were used in porous ceramics. A slip was obtained by adding the powders to a solution 1.0 wt% of deflocculant, respectively. The specimen obtained by casting a polyurethane foam with 0.5wt% into a slip, and drying it under vacuum, was heated at 1150, for 3 hours. The porous ceramics samples about 0.5g were individually soaked into 30 mL of phosphate buffer saline (PBS) at 20 for 1,3,7 and 10 days, respectively. The calcium content of the PBS solution was analyzed by (ICP). The porous bodies were filtered, dried, and characterized using SEM, XPD, and FT-IR.
Biocompatibility Evaluation of Lithium-Hydroxyapatite Composites
Authors: Valério Patricia , Oktar Faik N. , Göller Gültekin , Ozyegin L.S. , Shainberg A.P.M. , Goes Alfredo , Leite M. Fatima
Published: March 2009

Fifteen different lithium-hydroxyapatite composites were tested in this work. LiHA were prepared using 0.25 %, 1 % and 2 % of lithium and five different sintering temperature 900, 1000, 1100, 1200 and 1300oC. Primary culture of osteoblasts were used to evaluate the biocompatibility of the samples, concerning to cell viability and alkaline phosphatase production. The 1% LiHA samples sintered at 1100, 1200 and 13000C showed the best results.
Rietveld Studies on Silicon Substituted Hydroxyapatite
Authors: Zou Shuo , Huang Jie , Best Serena , Bonfield William
Published: March 2009

Silicon-substituted hydroxyapatite (SiHA) attracts particular interest due its enhanced bioactivity compared with pure hydroxyapatite. In this study we seek to clarify the effects on the lattice parameters of both composition and sintering temperature in experimentally-produced HA and 0.8wt% SiHA, 1.5wt% SiHA and 2.0wt% SiHA sintered at 800oC and 1200oC. X ray diffraction was
used to determine the phase purity and crystallographic structure. We found that while the c parameter increased with increasing silicon concentration, the a parameter decreased with initial silicon incorporation then recovered with further increases in silicon incorporation. The calcium (2)
channel expanded with silicon incorporation while tetrahedron distortion index (TDI) and the radius of the P channel showed a similar dependence on silicon content as the a parameter.
Densification of Zirconia–Hydroxyapatite Ceramics Without Phase Changes
Authors: Adolfsson Erik , Shen Z.
Published: March 2009

Zirconia-hydroxyapatite (40-60 vol%) composites were sintered at different temperatures in air. The x-ray diffraction patterns of the sintered composites showed that hydroxyapatite began to decompose to tricalcium phosphate even below 950°C. The decomposition of hydroxyapatite also involved release of structural water, which was studied using thermogravimetric analysis. By reducing the loss of structural water from the hydroxyapatite, the phase stability of the hydroxyapatite could be increased. This allowed higher temperatures to be used during the densification process where dense composites without any detectable reactions where produced by hot isostatic pressing at 1200°C as well as with spark plasma sintering at 1100°C.
Biocompatibility of CaSiO3 /High-Density Polyethylene Composites Prepared by Hot-Pressing
Authors: Tanuma Miho , Kameshima Yoshikazu , Nakajima Akira , Okada Kiyoshi , Asai Shigeo , Sumita Masao
Published: March 2009

We have reported that CaSiO3 ceramics show very fast bone-like apatite formation in simulated body fluid (SBF). However, CaSiO3 ceramics have disadvantages in their mechanical properties and shapability. It is therefore more effective to develop composites of CaSiO3 particles dispersed in a matrix of polymer or metal. Such composites are usually prepared by homogeneously blending the ceramic powder with the matrix component. This method is, however, ineffective for the preparation of biocompatible polymers or metals because only the surfaces containing accidentally-exposed ceramic particles play a role in generating apatite in SBF.
It is therefore necessary to add a large volume of ceramic powder and also to abrade the surface to expose more of the ceramic particles. In this study, CaSiO3/high-density polyethylene (HDPE) composites were prepared by hot-pressing to introduce surface CaSiO3 particles and their
biocompatibilities were evaluated under in vitro conditions using SBF. CaSiO3 powders were spread on a HDPE plate and hot-pressed at 140oC and 4.9-14.7 MPa for 2 min. The composite sample (about 10×10×1 mm3 in size) was immersed in 30ml SBF (sample/solution ratio of 2.5 g/l)
at 36.5oC. After 14 days soaking, the apatite product particles covered most of the composite surface and formed apatite layers. Bone-like apatite particles were formed only on the surface regions containing exposed CaSiO3 particles but no apatite was formed on the CaSiO3 particles buried in the HDPE matrix. The results show that this surface deposition method is very effective in developing biocompatibility in the composites using very small amounts of CaSiO3 powder (about <1 %v) compared with results reported for hydroxyapatite and AW glass-ceramic powders
(requiring about 40 %v). It is also found that the inhomogeneous state of the CaSiO3 particles in the surface of the present composites strongly influences their biocompatibility. It will be necessary to improve the homogeneity of CaSiO3 dispersion in the surface of the composites to achieve a more uniform surface apatite layer.
Long-Term Reliability Assessment of Bioceramics for Artificial Joints Using Microdamage Monitoring by AE
Authors: Wakayama Shuichi , Kawakami Teppei , Ikeda Junji
Published: March 2009

Microfracture process during bending tests of alumina ceramics used for artificial joints was evaluated by acoustic emission (AE) technique. Four-point bending tests were carried out in air, refined water, physiological saline and simulated body fluid. AE behavior during bending test inhibited the rapid increasing point of AE events and energy prior to the final unstable fracture. It was understood that the bending stress at the increasing point corresponds to the critical stress for
maincrack formation. The critical stress was affected by water in environments more strongly than fracture strength. Consequently, it was suggested that the characterization of maincrack formation is essential for the long-term reliability assessment of load-bearing bioceramics.
A New Testing Method for Ceramic Hip Joint Heads According Conditions In Vivo
Authors: Oberbach Thomas , Salomon Dirk , Glien Wilfried
Published: March 2009

A new test method for the determination of the static burst strength of ceramic hip joint heads is described. The common test method is the test with an axial direction of the compressive force. In the following publication a finite element analysis of the stress distribution in ceramic heads under angular loading is shown. The results concerning the location of the highest hoop and tensile stresses are compared with the results of experimental tests for the determination of the static
burst load of ceramic heads under a load direction of 25°.
Development of Piezo-Spectroscopic Techniques for Nano-Scale Stress Analysis in the Scanning Electron Microscope of Zirconia Bioceramics Based on Rare-Earth Fluorescence
Authors: Yamada Kiyotaka , Ikeda Junji , Pezzotti Giuseppe
Published: March 2009

The electro-stimulated luminescence spectrum of a rare-earth ion added to zirconia (ZrO2) lattice was investigated with the aim of using it as a sensor for nano-scale stress (fluorescence piezo-spectroscopy) and phase transformation assessments in a field emission scanning electron microscope (FE-SEM). In this paper, the selected rare-earth fluorescent ion Eu, added to ZrO2 as a raw oxide powder (Eu2O3) before sintering (in the amount of 1.0 wt. %). Spectroscopic results indicated that the spectral shift of some fluorescent band of the selected rare-earth ion was sensitive to residual stress and that the electron-stimulated spectra of Eu2O3-doped ZrO2 in its tetragonal and monoclinic polymorphs were different to each other. Based on these findings, the luminescent substance can be useful as a “stress and phase transformation sensor”, in order to clarify the elementary mechanisms behind synthetic ZrO2.
Osteogenic Differentiation of Marrow Mesenchymal Stem Cells (MSCs) on Ceramic Total Joints - Significance of Patient's Serum for Proliferation and Differentiation of MSCs -
Authors: Ohgushi Hajime , Machida Hiroko , Oshima Akira , Kotobuki Noriko , Hirose Motohiro , Fujisawa Akira , Tanaka Yasuhito , Takakura Yoshinori
Published: March 2009

After culture expansion of mesenchymal stem cells (MSCs) from a few milliliter of fresh patient’s bone marrow, we applied the MSCs on alumina ceramic ankle prosthesis and further cultured in an osteogenic medium for 2 weeks. After the culture, the MSCs differentiated into osteoblasts, which fabricated bone matrix on the surface of ceramic prosthesis. The expansion of MSCs followed by osteogenic differentiation was done using the commercially available medium with some chemicals and patient’s own serum. The MSCs well proliferated and differentiated into osteoblasts, even the MSCs were from old aged (more than 70 years old) patients. The tissue engineered ceramic prostheses were implanted into osteoarthritic patients. Typical X-ray findings showed that radiodense areas began to appear around the cell-seeded areas on the prosthesis about 2 to 3 months after the operation. These findings confirmed the importance of tissue engineering approach for early bone fixation and the approach can be done using small number of bone marrow cells and patient’s own serum without adding animal-derived products.
A Practical Method for Clinical Veterinary Use: Use of Dentine Hydroxyapatite (DHA) as a Graft Material
Authors: Oktar Faik N. , Ozsoy S. , Altıntaş S.
Published: March 2009

This study demonstrates the use of human dentine derived hydroxyapatite (DHA) as an easily prepared graft material in 23 dogs and 5 cats with various orthopaedic problems. Results of these cases were evaluated clinically and radiographically. This study reveals that DHA can be used safely in animals and is an effective graft material.
Immediate Mechanism of the Osteoconductivity of the Polarized Hydroxyapatite
Authors: Nakamura Miho , Sekijima Yasutaka , Nakamura Satoshi , Niwa Kazuki , Kobayashi Takayuki , Yamashita Kimihiro
Published: March 2009

We investigated the immediate response in the vicinity of the implanted polarized hydroxyapatite (HA). One of the important immediate events was found to be the fibrin adsorption on the implanted HA. The activation of the fibrin adsorption on the polarized HA was confirmed by the observation by SEM observation and immunohistochemical detection. After the implantation, the coagulation cascade induced the wound healing. The adsorbed fibrin was formed network structure and worked for later cell responses as the scaffolds. The acceleration of fibrin scaffolds formation in the vicinity of the implanted polarized HA contributed to the stimulation and activation of platelets and osseous cells. The platelets were activated from the results of the signal transduction and cytoskeleton changes and released growth factors. The growth factors released from platelets led to bone regeneration by stimulating migration and proliferation of the osseous cells. In the vicinity of the implanted HA samples, the coagulation cascade reaction to repair wound healing led to the new bone formation by mediation of the platelets and osseous cells. The mechanism of osteoconduction at earlier stage had close relationships to the electrostatic properties of the implant.
Castability and Biocompatibility of Novel Fluorcanasite Glass-Ceramics
Authors: Bandyopadhyay-Ghosh S. , Reaney Ian M. , Johnson A. , Brook I.M. , Hurrell-Gillingham K. , Hatton P.V.
Published: March 2009

Novel fluorcanasite based glass-ceramics were produced by controlled two stage heattreatment of as-cast glasses. Castability of parent glasses was determined using a graduated spiral cast piece. Fluorcanasite glasses were also cast to form complex shapes using the lost wax casting technique. Gypsum and phosphate bonded investments were used to investigate their effect on the
casting process, cast surface crystallinity and biocompatibility. The stoichiometric composition had the greatest castability but the other two modified compositions also had good castability. X-ray diffraction showed similar bulk crystallisation for each glass irrespective of the investment material. However, some differences in surface crystallisation in the presence of different investment materials were detected. Discs cast using gypsum bonded investment showed greater in vitro biocompatibility than equivalent discs cast using phosphate bonded investment under the conditions
used. Gypsum and phosphate bonded investments could both be successfully used for the lost wax casting of these novel fluorcanasite glasses.
Effect of Ion Release on Antibacterial Activity of Melt-Derived and Sol-Gel-Derived Reactive Ceramics
Authors: Vaahtio Minna , Munukka Eveliina , Leppäranta Outi , Zhang Di , Eerola Erkki , Ylänen Heimo O. , Peltola Timo
Published: March 2009

Four different bioreactive ceramics were prepared using a sol-gel method and a standard melting process. The aim was to study antibacterial effect of these materials on the growth of Staphylococcus epidermidis. The dissolution (Si and Ca ions) of fine (≤ 45 !m) ceramic powders in a tryptone soya broth (TSB) was investigated. Also the pH changes in TSB solution were measured. In addition the adherence of Enterococcus faecalis (Ef) to materials was investigated. The bacterial adhesion was studied using scanning electron microscopy (SEM). In the bacterial and the adhesion test, CaPSiO2 and S53P4 had the strongest antimicrobial effect against studied bacteria. It was shown that bioreactive sol-gel derived ceramic with sufficient high Ca ion release (> 270 ppm) can reach strong antibacterial effect also at lower pH values (< 9.6).
Direct Deposition of a Rutile Layer on Polymer Substrates to Induce Bioactivity In Vitro
Authors: Wu Jin Ming , Wang Min , Hayakawa Satoshi , Tsuru Kanji , Osaka Akiyoshi
Published: March 2009

Rutile films were deposited on polytetrafluoroethylene (PTFE) substrates using 1.5 M titanium tetrachloride aqueous solution at 60 °C. The rutile films exhibited excellent in vitro bioactivity as they induced apatite deposition in a simulated body fluid (SBF) within 2 days. Chlorine incorporated in the rutile films did not inhibit apatite deposition.
Cellular Response Assessment to Zirconia-Alumina Composite: An In Vitro Experimental Study
Authors: Kim Dae Joon , Han Jung Suk , Lim Young Jun , Jang Kyung Soo , Ahn Chang-Young
Published: March 2009

The biocompatibility of zirconia-alumina composite was evaluated with HOS osteoblast like cell models. A total of 18 zirconia-alumina composite disc (diameter: 19mm and thickness: 1.5mm) were prepared and divided into two groups. Half of the discs were sandblasted with 50µm alumina particles. Mean values of surface roughness (Ra) were 0.1 µm and 0.9-1.48 µm for smooth and sandblasted sample respectively. The cell attachment, proliferation, and differentiation on the
specimen were evaluated by the Real-Time Polymerase Chain Reaction (RT-PCR), Methylthiazole Sulfate (MTS) analysis, Alkaline Phosphatase (ALP) activity, and Scanning Electron Microscopy (SEM). There was no significant difference in cellular response between two groups. The analysis
of the RT-PCR showed that the amount of Cyclin D1(mRNA expression) was not statistically significant different between two groups after 24 hours as well, however markedly decreased in the smooth surface after 72 hours. This indicated that the rough one might have a more favorable cellular proliferation compared to smooth one in long term evaluation. Further study will be necessary.
Apatite Formation on Zirconia Based Composites
Authors: Cortés-Hernández Dora A. , Ortega Sergio , Nogiwa-Valdez Akemi A.
Published: March 2009

Bioactive Mg-PSZ composites were developed by using wollastonite ceramics either as a constituent of the composite formulation or as a bioactive bed during the biomimetic treatment in simulated body fluids. The zirconia composites were prepared by uniaxial pressing of powder mixtures and sintered at 1550oC in air. Wollastonite containing zirconia/alumina composites were also sintered at 1350oC. The composites were immersed in SBF for 7 days on a bed of wollastonite
powder and then re-immersed in 1.5SBF for 7 days. Tests were also performed with no wollastonite bed. A highly bioactive surface was observed on the Mg-PSZ/CaSiO3 and Mg-PSZ/Al2O3 composites. A homogeneous apatite layer was detected on the Mg-PSZ/CaSiO3 composites immersed for only 7 days in SBF. No apatite was formed on the Mg-PSZ/Al2O3/CaSiO3 composite.
During the sintering mechanism at either 1550 or 1350oC small amounts of aluminosilicate phases are formed. These phases inhibited the apatite formation.
In Vitro Bioactivity of Bi-Structured Nano-Hybrids in the CaO-SiO2-PTMO System
Authors: Koh M.-Y. , Kim Hyun Min , Lee H.K. , Lee Kang Yong , Lee Y.H. , Kwak J.
Published: March 2009

Synthetic model of a large transparent crack-free monolithic ceramic-polymer hybrid, which was synthesized using triethoxysilane end-capped poly(tetramethylene oxide) (Si-PTMO) and tetraethoxysilane (TEOS), was examined in the CaO-SiO2-PTMO sol-gel system. Bulk precursor with nominal mass ratio of PTMO: TEOS = 80: 20 and surface precursor with nominal molar ratio of TEOS: Ca(NO3)2 = 1: 0.3 were subjected to hybridization through hydrolysis and condensation process, producing a bi-structured hybrid in which polymeric bulk was molecular hybridized with bioactive silicate surface. Spectroscopic and microscopic characterizations revealed that the surface of hybrid was typical bioactive silicate. In vitro study using a simulated body fluid (SBF) revealed that the hybrid formed an apatite on its surface within 6 hours in SBF, suggesting bioactive materials with high capability of tissue integration as well as polymeric physical properties.
Development of Nanophase β-Tricalcium Phosphate/Collagen Fiber Composites for Improving Cell Adhesion and Proliferation
Authors: Guan Bing Gang , Yan Wei Qi , Yang Di Sheng , Zou Chao , Weng Wen Jian
Published: March 2009

A novel porous beta-tricalcium phosphate /collagen fibers (β-TCP/CF) composite, having a well-dispersed nano-sized β-TCP in collagen matrix, was developed by a wet-chemical method. The nano-composite was compared to conventional β-TCP on cytocompatibility by cell attachment, proliferation, alkaline phosphotatse (AKP) activity and scanning electron microscopy (SEM) analysis. These in vitro assays showed that the β-TCP/CF composite elicited cell adhesion and proliferation better then controls. Moreover experiments on osteoblast-like cells showed improved cell growth with the highly characterized nanophase structure. SEM micrographs also showed that the nano-sized composite exhibited much more viable cells in attachment on the surface compared with the controls. At 1, 3 and 5 days, AKP activity was not significant different for the tested and control samples, while at 7 day after culture, significantly increased AKP activity was observed for β-TCP/CF than for the control. The in vitro results obtained confirmed the remarkable improvement of cell adhesion and proliferation of the nano-sized β-TCP/CF composite, which may be a new promising candidate for tissue engineered bone substitute.
Shear Stress Studies of Plasma-Sprayed Teeth Derived Hydroxyapatite on Titanium
Authors: Oktar Faik N. , Ozgen F. , Altıntaş S.
Published: March 2009

The purpose of this study was to develop a biologically derived fluor rich hydroxyapatite (HA) for plasma spraying purposes by a simple way. HA was derived from human teeth and processed in laboratory conditions as plasma coating material. For manufacturing data HALL flowability, shear stress, SEM, metallography, X-ray diffraction and ion analyzing tests were performed. Implant prototypes were prepared from titanium rods, which were coated with HA powder with a plasma coating unit. Statistical studies were also done to test the performance for
plasma coatings. All results showed that this production method enables the manufacturing of HA powders with biological origin for plasma spraying purposes compared with other time consuming and delicate methods. Powder morphology developed by selective grinding process was a key parameter to start such a production line in industry.
Different Morphology of Hydroxyapatite Coatings on Titanium by Electrophoretic Deposition
Authors: Meng Xian Wei , Kwon Tae Yub , Kim Kyo Han
Published: March 2009

Commercial hydroxyapatite powders were electrophoretically deposited on titanium
substrates. In this study, the effect of deposition durations and applied voltages on deposition yield was investigated. Green and sintered coatings were studied by SEM and XRD. It was observed that by applying low voltages and presedimentation, uniform and smooth hydroxyapatite coating can be prepared. In order to obtain roughened hydroxyapatite coatings, high voltages have to be applied. It was concluded that experimental conditions of powder concentration, applied potential,
and presedimentation have a significant effect on the deposited coating morphology.
Sol-Gel Derived Biphasic HA/FA Coatings
Authors: Cheng Kui , Weng Wen Jian , Miao Shun Dong , Du Pi Yi , Shen Ge , Han Gao Rong
Published: March 2009

In order to optimize the dissolution resistance, cell attachment and Ca and P releasing ability of the calcium phosphate coatings, Hydroxyapatite/fluorapatite (HA/FA) biphasic coatings are prepared and characterized. Ultrasonically dispersing of HA powders in the mixed ethanol solution of Ca(NO3)2, P2O5 and HPF6, to form a “colloidal sol” for dip coating. The coatings are prepared on Ti6Al4V substrate by dip coating, 150oC drying and 600oC firing. The coatings are
characterized by X-ray Diffractometer for the crystalline phase, X-ray Photoelectron Spectroscopy for chemical composition and Scanning Electron Microscopy for the surface morphology. The results show biphasic HA/FA coatings with homogenous distribution of HA particle in the FA matrix can be obtained. The nominal F content of the coatings decreases with the increasing amount of HA, and the surface morphology is rough. These demonstrate the obtained biphasic HA/FA
coatings are suitable to response to cells, accelerating bone formation.
Preparation of Apatite-Polyglutamic Acid Hybrid Through Biomimetic Process
Authors: Sugino Atsushi , Miyazaki Toshiki , Ohtsuki Chikara , Tanihara Masao , Kuramoto Koichi
Published: March 2009

Natural bone has excellent mechanical properties such as high fracture toughness and high flexibility. These properties are achieved by specific microstructure of natural bone that is composed of the organic collagen and inorganic apatite. On the basis of these findings, apatite-polymer hybrids are expected as novel bone substitutes having excellent mehcanical performances and high bone-bonding ability, i.e. bioactivity. In this study, we attempted preparation of apatite-polyglutamic
acid hybrids through biomimetic process that mimics the principle of biomineralization. Simple chemical modification of the polyglutamic acid gel with 1 M (= mol/L) calcium chloride solution provided the gel with apatite-forming ability in simulated body fluid (SBF, Kokubo solution). This type of hybrid is also useful for designing bioactive bone substitutes with injectability, since viscosity of the polyglutamic acid gel can be easily controlled according to degree of cross-linking.
Topography Control of Hydroxyapatite Coatings
Authors: Gross Kārlis A. , Müller D.M.
Published: March 2009

The biomaterial surface represents the first contact point for proteins and cells and is thus critical to optimise the features to transmit the best signals for tissue and organ regeneration. Both chemistry and topography are surface characteristics that can be modified by the manufacturing process and provide signals to cells. While chemistry and crystallinity have received attention for thermally sprayed hydroxyapatite coatings, the control of the surface microtopography has not been
addressed. This study collected a range of implants with a coating and assessed the topography on dental implants, orthopaedic screws and hip prostheses. The surface was found to be composed of large topographic features (angular particulate and smooth areas) and micron sized aspects (fine
grains, cracks and ridges). Thermal spray experiments were designed to determine the influence of processing conditions on droplet spreading. This knowledge was then applied to see the effect of different parameters on the final coating topography. The parameters investigated for their influence
on the surface topography included substrate roughness, substrate temperature, spray distance and particle size. The particle size showed the largest influence on altering the roughness, Ra of the coating. A two-fold increase in particle size doubled the roughness from Ra of 4.8 µm when the powder was sprayed under the same conditions.
Thin Sol-Gel Films on Fracture Fixation Material for the Controlled Release of Antibiotics
Authors: Radin Shula , Parvizi Javad , Ducheyne Paul
Published: March 2009

Previously, the properties of room temperature processed silica sol gel (also called xerogels) as resorbable and biocompatible controlled release systems were described. It was demonstrated that drugs and macromolecules with a variety of properties and characteristics could be released in a controlled manner. In this study, we focus on the synthesis of antibacterial thin solgel films on intramedullary nails and fracture fixation materials. We determine the effect of processing parameters on the in vitro properties and demonstrated a time- and load- dependent release of vancomycin from the film. This study suggests that thin sol-gel films hold great promise for the prevention and treatment of bone infections.
Formation of FGF-2-Apatite Composite Layer on Hydroxyapatite Ceramic
Authors: Sogo Yu , Fukasawa Koshiro , Ito Atsuo , Ichinose Noboru
Published: March 2009

A FGF-2-apatite composite layer was formed on hydroxyapatite (HAP) ceramics using supersaturated calcium phosphate solutions containing various amounts of potassium chloride. The optimum conditions for the formation of the composite layer were determined by using cytochrome C (cyt C), one of the dummy proteins of FGF-2, and an immersion solution with a Ca/P molar ratio of 0.19 and a potassium chloride concentration of 8 mM. The amounts of cyt C and FGF-2 immobilized in the composite layer were 1.28±0.30 and 3.18±0.01 µg cm-2, respectively. The release of FGF-2 from the composite layer continued for at least 3 days. It was considered that the release period of FGF-2 could be extended to day 10 because the release of cyt C continued for at least 10 days. When the composite layer is formed on commercial bone substitutes, it is expected that the promotive effect on bone formation around the bone substitutes will continue for at least 10 days.
A Comparison of the Bone-Like Apatite Formation Potency Between Hydroxyapatite and β-Tricalcium Phosphate in Glass Ionomer Dental Luting Cement
Authors: Yoon S.I. , Lee Yong Keun , Kim Kyoung Nam , Kim S.O. , Son H.K. , Kwak J.Y. , Kim J.Y. , Choi H.J.
Published: March 2009

Previous studies have shown that hydroxyapatite increases the bonding strength of dental luting cement with human teeth by forming bone-like apatite when it is added to cement. However, due to the low solubility of the hydroxyapatite, its ability to form bone-like apatite decreases in protein-free acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The purpose of this experiment was to increase the formation of bone-like apatite by mixing hydroxyapatite with β-TCP of high solubility. RelyXTM glass ionomer cement(3M/ESPE, USA) was used as dental luting cement. Film thickness, setting time, and compressive strength was measured for each group of 15% hydroxyapatite, 15% β-TCP, and 15% mixed hydroxyapatite and β-TCP (85:15). Every specimen of each group was immersed in the simulated body fluid for four week before measuring bonding strength, and then their sectional surface was observed under SEM. The most noteworthy result was that the group containing β-TCP produced more amount of bone-like apatite compared with the group composed of only hydroxyapatite.
Surface Properties and Cytocompatibility of Bio-derived Compact Bone as Scaffolds for Tissue Engineering Bone
Authors: Qin Ting Wu , Yang Zhi Ming , Li Xiu Qun , Mo Xiang Tao , Luo Jing Cong , Xie Hui Qi
Published: March 2009

Many scaffolds are candidates for use in tissue engineering approaches for the repair or replacement of bone defects. Among the scaffolds tested for tissue engineering of bone, bio-derived compact bone scaffold (BDCBS) containing mineralized collagen fibers, phosphorus and calcium, as natural bone does, is one of the most promising candidates for this purpose. To analyze how appropriate the BDCBS would be for tissue engineering purposes, we established an in vitro characterization system to describe the surface properties and cytocompaibility of the scaffold. Surface properties were determined by means of scanning electron microscope and scanning probe microscope. The surface phase was examined with the Fourier transform infrared spectroscopy and X-ray diffraction. Osteoblasts from human embryos were isolated from the periosteum. After in vitro expansion, cells were cultivated on the BDCBS. Real-time cell culture was used to monitor the growth process of cells seeded on the scaffold. Using this in vitro characterization, we were able to demonstrate effective growth of osteoblasts on this scaffold. In summary, BDCBS has the surface characterization similar to a natural bone and also has strong affinity for osteoblast attachment and proliferation, indicating the potential as an effective scaffold used in tissue engineering bone.
Novel Calcium Phosphate Ceramics: The Remarkable Promoting Action on the Differentiation of the Normal Human Osteoblasts
Authors: Tamai Masato , Nakaoka Ryusuke , Isama Kazuo , Tsuchiya Toshie
Published: March 2009

To promote the activity of normal human osteoblasts (NHOst), the novel HAp ceramics containing Nb ions (NbHAp) were synthesized by wet chemical process, which reacting aqueous solution containing a mixture of Ca(NO3)2, (NH4)2HPO4, and the Nb aqueous solution. X-ray diffraction
patterns indicated that NbHAp had a monolithic apatitic structure, although crystallite decreased as Nb content increased. From inductively coupled plasma analysis, maximum amount of Nb ions in the sample was almost 8.2atom% of P ions. The NbHAps were presented as aggregates and composed of fine crystal of <1µm in diameter. Nb ions in NbHAp were uniformly distributed in the aggregates. Furthermore, high-resolution XPS spectra of Nb 3d5/2 indicated that Nb ions in the
HAp were presented as Nb5+. These results suggested that Nb ions were at PO4 site in crystal structure of HAp. When NHOst were cultured with the NbHAp, their ALP activity were twice as much as that of NHOst cultured with HAp without Nb ions.
Osteoblast Behavior at the Surface of CO3Ap-Collagen Sponges
Authors: Okazaki M. , Tieliewuhan Y. , Hirata I.
Published: March 2009

Carbonate apatite (CO3Ap) was synthesized at 60+1°C and pH 7.4+0.2, to develop a new biodegradable scaffold biomaterial. The synthetic CO3Ap was mixed with a neutralized collagen gel and the CO3Ap-collagen mixtures with different kinds of CO3Ap contents and porosity were frozen and dried in lyophilized into the sponges. CO3Ap-collagen mixtures were also lyophilized into sponges in a HAp frame ring with 0.5 mm pores. To examine the degree of cell
invasion, mouse MC3T3-E1 cells were grown in αMEM with 10% heat-inactivated FBS in 96-well plates containing the CO3Ap-collagen sponges at 37°C in a 5% humidified atmosphere. Under pentobarbital anesthesia, samples of UV-irradiated CO3Ap-collagen sponges with frames were surgically implanted beneath the periosteum cranii of rats. SEM observation of CO3Ap-collagen
sponges showed favorable pores for cell invasion. Approximately 50~300 µm size pores seemed to continue into the deep bottom. X-ray high-resolution microtomography revealed a clear image of 3D structure of the sponges. 70 wt% CO3Ap-collagen sponge seemed to be most favorable
biomaterial from the viewpoint of the natural bone properties. Then, to avoid the shrinkage of the sponges, we successfully made a hybridized CO3Ap-collagen sponge with a frame. When these sponge-frame complexes were implanted beneath the periosteum cranii of rats, newly created bone was observed toward the inner core of the complex from the surface of the periosteum cranii.