bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Shear Horizontal Acoustic Waves in an Inhomogeneous Magnetoelectroelastic Plate
Authors: Peng Fei , Hu S.Y.
Published: March 2009

This paper presents some useful discussions on the shear horizontal acoustic waves in an inhomogeneous plate that possess coupled piezoelectric, piezomagnetic, and magnetoelectric effects. The magnetoelectroelastic material is of hexagonal symmetry (6mm crystal) and polarized in the shear horizontal direction. It is assumed that the material constants of the magnetoelectric plate vary
continuously along the thickness direction. Solutions of the mechanical displacement, electric potential, and magnetic potential are obtained by solving the coupled field equations. The phase velocity equations are obtained and the influence of the inhomogeneity of the material constants on the phase velocity is considered. These findings are significant in the applications of wave propagation in the coupled piezoelectric, piezomagnetic, and magnetoelectric structures.
Fracture Strength Model for Jointed Rockmass and Its Application to Engineering
Authors: Zhang Qiang Yong , Zhu Wei Shen , Li Shu Cai , Xiang W.
Published: March 2009

There are large number of intermittently jointed cracks in rockmass, which exist in
rockmass as a kind of initial damage. It is their damage, propagation and propagating interaction that result in a variety of failure forms of rockmass. This paper conducts an in depth research on the influence of cracks propagation interaction upon fracture strength of jointed rockmass. A kind of fracture strength model for jointed rockmass is developed under three-dimensional stress conditions. With the utilization of this model in a large-scale highway slope project, the design and construction are effectively performed and remarkable economic benefit has been achieved.
Fatigue Crack Growth of Notched Tubular Specimen under Biaxial Loading Conditions
Authors: Lee Hyun Woo , Oh Se-Jong
Published: March 2009

Crack growth behavior of S45C notched tubular specimen was studied to predict fatigue crack initiation and crack propagation under biaxial loading conditions. Stress-strain field near the hole was analyzed by ANSYS. The crack initiation lives and the crack initiation locations were predicted from strain based theories, and the analysis results were compared with the test results. Crack propagation behaviors were studied to understand the reason of crack branching and crack growth rates changing under biaxial loading conditions. Crack growth direction was also observed to find the governing factors of the fatigue damage under biaxial loading conditions.
Investigation on Zonal Characteristics in Soil of Synchronous Explosion Forming
Authors: Shao Peng , Zhang Yong , Gao Wen Ming , Liu Yong Qiang
Published: March 2009

Synchronous explosion forming, which takes advantage of the thixotropy of concrete or cement mortar and the condensability of soil under blasting concussion, is a newly developed method to construct underground cavities. In this paper, the mechanism of the new method is elucidated first, and then the zonal characteristics in soil are investigated emphatically. In order to accomplish comparative analysis, both synchronous explosion forming and conventional compression blasting experiments are conducted under same soil and explosive conditions. Experimental results indicate that the zonal characteristics in soil by synchronous explosion forming differ from that of by conventional compression blasting. When the new method is applied, formation and growth of cracks in soil during blasting is restrained, and the crannied region, which is usually produced in conventional compression blasting can be substituted by a soil- cement mortar occlusive region. Additional, the compaction range in soil is large when the new method is used. The zonal characteristics of synchronous explosion forming are more advantageous to the bearing capacity of soil and secular stability of cavity.
Evaluation of the Fatigue Limit for Notched Parts Considering the Influences of Work Hardening and Residual Stress by Cold Working
Authors: Wang Sheng Wu , Wen Ai Ling , Nishida Shinichi , Hattori Nobusuke
Published: March 2009

Nearly 90% of failures of machines and mechanical parts are caused at the area of stress concentrated in the structural components [1]. Hence, it is important to investigate the method of improving fatigue strength for notched parts, and method of evaluation the fatigue strength of notched parts for mechanical engineering. In this paper, the tests were carried out for improving the fatigue strength of specimens, with the hole notches that have been chamfered by die-pressing. The
fatigue strength of notched part is enhanced to around 100% by die-pressing, comparing with notched specimen without die-pressing. Based on the above results, the new method for evaluation the fatigue strength with both the effects of work hardening and residual stress caused by the cold working. The estimated results by the method revealed good agreement with the tested results.
Comparison Optimization Analysis of the Location of Power House under Complex Geological Structure
Authors: Zeng Jing , Sheng Qian , Zhou Qing Chun
Published: March 2009

The power house of Yantan extended hydropower project, with complex geological
conditions such as fault f211 below the power house and quartzite on top of it, is a huge underground cavern with large span and high wall. In order to evaluate the stability of the power house surrounded by such complex geological structure, the numerical simulation excavation of power house with different location schemes were studied by the elasto-plastic 2D FEM method. The deformation and
evolutive process of the stress with the progress of excavation were analyzed. On the condition ensuring the whole stability of surrounding rock mass, comparison optimization analyses were conducted on the power house location scheme. The rational location scheme was demonstrated. The final analyses results show that: (1) The mechanical properties of quartzite and its relative location to
the power house has no obvious influence to the stability of surrounding rock mass.(2) The f211 is the main bad geological structure which affect the stability of power house. (3) The case of moving 10m upward of power house is the most rational scheme for the whole stability of power house. (4) The Supporting measures, which would has an obvious effect in controlling the influence on the stability of surrounding rock mass by weak geological structure, are suggested at the out-crop of f211.
Numerical Analysis of 3-D FLAC on Supporting Effects of Underground Caverns Surrounding Rockmass of Xiao Lang Di Key Water Control Project
Authors: Liu Jian Hua , Zhu Wei Shen , Li Shu Cai
Published: March 2009

This present paper describes the process and methods of the numerical analysis, including yielding criterion, 3-D geometrical model, rock mass mechanical parameters, initial geostress field, method to simulate excavation process, simulation method for supporting structures. Then, the paper gives the computational results of rock deformation and stability for the large cavern group and comparisons for three cases: with no supporting structures; with bolts and shotcrete lining but no prestress-cables and with all the supporting structures of bolts, cables and lining. Finally, the paper reaches several conclusions.
Metamodel-Based Shape Optimization of Connecting Rod Considering Fatigue Life
Authors: Lee Tae Hee , Jung J.J.
Published: March 2009

To optimize a connecting rod satisfying fatigue life, metamodel-based design optimization is proposed. To approximately predict both volume and fatigue life of connecting rod, kriging metamodel is constructed based on maximin eigenvalue sampling. Fatigue analysis is accomplished for the calculation of fatigue life. The results of metamodel-based design optimization are compared with those of classical optimization. The advantages of metamodel-based optimization are discussed.
Detection Probability Improvement for Nondestructive Evaluation Using a Magnetic Camera
Authors: Lee Jin Yi , Hwang Ji Seoung , Choi Se Ho , Lim Jae Kyoo
Published: March 2009

It is important to estimate the intensity distribution of a magnetic field as a possible magnetic method in an industrial nondestructive evaluation application. A magnetic camera provides the distribution of a quantitative magnetic field with homogeneous lift-off and same spatial resolution. Magnetic flux leakage near a crack on the specimen can be amplified by using a 3- dimensional magnetic fluid, that is to say a magnetic lens. This study introduces the experimental consideration of the effects of magnetic lenses for concentrating of magnetic flux. The experimental results showed that the magnetic fluid has a sufficient lens effect for magnetic camera and effect of improvement in probability of detection.
Investigation on Stress and Strain Singularity in LEFM
Authors: Yang Zheng , Guo Wanlin , Liu Quan Liang
Published: March 2009

Stress and strain singularity at crack-tip is the characteristic of Linear Elastic Fracture Mechanics (LEFM). However, the stress, strain and strain energy at crack-tip may be infinite promoting conflicts with linear elastic hypothesis. It is indicated that the geometrical nonlinear near the crack-tip should not be neglected for linear elastic materials. In fact, the crack-tip blunts under high stress and strain, and the singularity vanishes due to the deformation of crack surface when loading. The stress at crack-tip may still be very high even though the singularity vanishes. The low bound of maximum crack-tip stress is the modulus of elastic in plane stress state, while in plain strain state, it is greater than the modulus of elastic, and will increase with the Poisson’s ratio.
Crash Zone Development for Railway Vehicle
Authors: Puja Ign Wiratmaja , Khalid  , Weij S.
Published: March 2009

This paper considers crash zone development for railway vehicle to improve it’s
crashworthiness characteristics. The principle of modification is by weakening the crash zone area and strengthening the passenger area. Thus the huge impact energy during collision will be absorbed by crash zone area so that it will maintain the structural integrity of the passengers. There are two type of modifications proposed in this study. The first modification is conducted by weakening the end-under-frame section and strengthening the middle-under-frame section. These
modification shows deformation characteristics improvement where the passenger area structure are not suffered from buckling and plastic deformation as expected. The second type of modification is full modification on end-under-frame. These modifications give better improvement on the deformation and energy absorption characteristics, however in the practical application, this will be more expensive option.
Evaluation of Adhesive Strengths of Plasma-Sprayed CoNiCrAlY Coatings Using an Indentation Method
Authors: Waki Hiroyuki , Nishikawa Izuru , Ohmori Akira
Published: March 2009

Thermal barrier coating (TBC) on the element for high temperature service, such as a gas turbine blade, has become an indispensable technology. In this study, adhesive strengths of plasmasprayed CoNiCrAlY coatings were examined using an indentation method. In order to examine the effects of the spraying process on the adhesive strength of a sprayed coating, coatings were deposited by both atmospheric plasma spraying (APS) and low pressure plasma spraying (LPPS). The half number of CoNiCrAlY(LPPS) specimens were thermally aged for diffusion treatment. The load-displacement curves during the indentation were measured, and the delamination energy per unit area of delamination was estimated. The delamination load was high when the distance from an edge of a specimen was long, however the energy per unit delamination area was almost independent of the distance from the edge and was uniquely determined. The delamination energy of CoNiCrAlY(APS) and CoNiCrAlY(LPPS) coatings were found to be approximately the same. The delamination energy of CoNiCrAlY(LPPS) with diffusion thermal treatment was widely scattered as compared with foregoing two coatings, however the energy of the CoNiCrAlY(LPPS) coating with diffusion thermal treatment was found to be about three times higher than those of both
CoNiCrAlY(APS) and CoNiCrAlY(LPPS) coatings. It was concluded that diffusion thermal treatment was effective in improving the delamination strength. The CoNiCrAlY(LPPS) coating with diffusion thermal treatment was also found to be effective in improving the fatigue fracture life of a thermal-barrier-coated material.
A New Boundary Integral Equation Method for Cracked Piezoelectric Bodies
Authors: Wu Kuang-Chong
Published: March 2009

A novel integral equation method is developed in this paper for the analysis of two-dimensional general piezoelectric cracked bodies. In contrast to the conventional boundary integral methods based on reciprocal work theorem, the present method is derived from Stroh’s formalism for anisotropic elasticity in conjunction with Cauchy’s integral formula. The proposed boundary integral equations contain generalized boundary displacement (displacements and electric potential) gradients and generalized tractions (tractions and electric displacement) on the non-crack boundary, and the generalized dislocations on the crack lines. The boundary integral equations can be solved using Gaussian-type integration formulas without dividing the boundary into discrete elements. The crack-tip singularity is explicitly incorporated and the generalized intensity factors can be computed directly. Numerical examples of generalized stress intensity factors are given to illustrate the effectiveness and accuracy of the present method.
Time-Dependent Effect of Viscoelastic Substrate on a Cracked Body under Inplane Load
Authors: Chang Rwei Ching , Chao Ching Kong , Chuang C.T. , Yang P.H.
Published: March 2009

Theoretical and experimental methods dealing with the effect of a viscoelastic substrate on a cracked body under inplane load are presented in this article. A generalized trimaterial solution is solved as a convergent series in terms of complex potentials via the successive iterations of the alternating technique in order to satisfy the continuity condition along the interfaces between dissimilar media. This trimaterial solution is then applied to the problem of a finite thickness layer bonded to a half-plane substrate. Using a standard solid model to formulate the viscoelastic constitutive equation, the real time stress intensity factors can be directly obtained from the Laplace domain. In the experiment, an aluminum cracked plate bonded to a polymer substrate is tested in a tension machine, where the displacement of the specimen is recorded by a high precision digital camera. The time-dependent stress intensity factor is determined by an inverse calculation through the crack opening displacement. The comparisons between the theoretical and experimental results are discussed in the final.
Manifold Method and Its Applications for Modeling Fracturing in Solids
Authors: Wang Shui Lin , Feng Xia Ting , Jiao Yu Yong , Ge Xiu Run , Li Chun Guang
Published: March 2009

A numerical technique based on using manifold elements in finite element method, for
modeling propagation of arbitrary cracks in solids, is described. When the region with crack(s)is subjected to external loading and the crack(s) starts to extend, the crack growth may intersect boundaries of nearby finite elements. Those intersected finite elements are replaced by manifold elements. The technique, by which the initial finite element mesh can be kept unchanged during the processes of crack propagation, is called manifold elements in finite element method. The crack growth is governed by the theories of linear elastic fracture mechanics. The stress intensity factors are computed by a contour integral technique and crack trajectory is determined by applying the maximum tangential stress criterion. Finally, test examples are given to verify the new method and the predicted trajectories are compared to experimentally obtained crack growth paths with good agreements
Utilization of Numerical Techniques to Predict the Thermal Behavior of Wood Column Subjected to Fire Part B: Analysis of Column Temperature and Fire Resistance
Authors: ElShayeb Mohamed , Malik Abdul Rashid Ab , Ideris Fazril , Hari Zolman , Razak Norhaida Ab , Siang Jacqueline Eng Ling , Anuar Zulfika
Published: March 2009

Mathematical models of Part A [1] are used to calculate the temperatures, deformations and fire resistance of rectangular, hexagonal, octagonal and I-cross section columns for the purpose of Part B. In this paper the comparison among the configurations of the column has been carried out to predict the temperature history for the column elements for preventing the spread of fire and prolonging the structural time collapse. The columns are varied in section size, among them are the
rectangular, hexagonal, octagonal and I-cross section column of Keruing timber. The developed mathematical models defined the failure point as the point which the column can no longer support the applied load. From the comparison, the I-cross section column is the worst configuration than the other configuration.
Study on Self-Consistent Mesh Generating Method of Hexahedron Element Based on the Local Waveform Method with Damping
Authors: Gheni Mamtimin , Wang X.F. , Kikuchi Masanori
Published: March 2009

Three-dimensional finite element method (FEM) is widely used as an effective numerical simulation technique to solve the complex engineering problem. In the FEM simulation technique at first it needs to discrete the problem. However, the almost all of the engineering problem have very complicated structure and shape, so that the mesh generation also have much difficulty. Furthermore, the correct generation of mesh is one of the most significant issues that directly affect to the accuracy of the FEM simulation. Though in extensive commercial software have an excellent automatic mesh generating system, however the problem of hexahedral automatic mesh generation and its adaptation are not enough to solve for practical applications, because for the mesh generation of complex shape is very difficult and still intensive labor work by hand. In this paper we present a new method to generate an appropriate mesh using existing regular hexahedral mesh and hexahedron mesh generation technique. This technique based on the wave transmits theory with damp named Waveform Mesh Generating (WMG) method. The results shown that the complex shaped FEM discrete hexahedral mesh model generated when shape of the side apply to regular mesh side as a waveform constraint.
Fracture Design of Metallic Matrix Crack for Bi-Materials
Authors: Li You Tang , Yan Chang Feng
Published: March 2009

The fracture designs of metallic matrix crack for bi-materials were studied. The stress field and displacement field of plane matrix crack was setup at first. Then the finite element method is used to analyses the stress singularity of matrix cracks between different materials. The solutions of stress singularity of a cracked bi-materials beam under uniform tension, and the three-point bending of bi-materials specimen were computed. The result lays a theoretic and applied foundation
for the practical engineering application of metallic matrix crack for bi-materials.
A Simple Mechanism Solution for Predicting the Collapse Loads of I-Beams Subjected to Concentrated Load
Authors: Fu Yi , Ji Xin Hua , Chen Jin Long , Qin Yu Wen
Published: March 2009

In order to solve the problem of web buckling for hot rolled I-beams without membrane subjected to concentrated load, a plastic mechanism analysis that involves consideration of the plastic hinges developing in the flanges and the yield lines forming in the web plate have been made, and a simple theoretical prediction of collapse loads have been developed. At the same time, wide ranges of finite element studies have been made. Based on the finite element results, certain approximations and empirical modifications are introduced because of the complex geometrical nature of the problem and the purpose to make the resulting design method simple enough for routine practical application. The theoretical results have been compared, and show close correlation, with the finite element results.
Effective Thermal Conductivity of Composites Reinforced with Curvilinearly Anisotropic Inclusions with Kapitza Contact Resistance
Authors: Chen Tung Yang
Published: March 2009

Effective thermal conductivities of composites consisting of curvilinearly anisotropic inclusions with Kapitza thermal contact resistance between the constituents are considered. We show that the effect of these curvilinearly anisotropic inclusions can be exactly simulated by certain equivalent isotropic or transversely isotropic inclusions. Three different micromechanical models are employed to estimate the effective thermal conductivity of the composite. Interestingly, all these methods result in the same simple, closed-form expression.
Effect of Ultrasound Waves on Resin-infiltrated Time of Wood Materials Using a Peak-Delay Measurement Method
Authors: Yang In Young , Kim Sun Kyu , Cha Cheon Seok , Sim Jae Ki , Park Je Woong , Hsu David K. , Im Kwang Hee
Published: March 2009

A nondestructive evaluation (NDE) technique would be very beneficial to assess resininfiltrated absorption effect of wood when wood was resin-treated. In this work, a wood material was nondestructively characterized and a technique was developed to measure ultrasonic velocity in wood using automated data acquisition software. We have proposed a peak-delay measurement method based on the pulse overlap measurement method. Also through transmission mode was performed to compare ultrasonic velocity with the above peak-delay measurement method in an immersion tank. The variation of ultrasonic velocity was measured and found to be somewhat consistent with those in infiltrated area in the course of nature absorption. For mapping out the material property inhomogeneity, through-transmission scans were used based on both amplitude and time-of-flight of the ultrasonic pulse. A peak-delay measurement method well somewhat corresponded to ultrasonic velocities of the pulse overlap method and through-transmission mode
and C-scan image signal based on peak-to-peak amplitude.
The New Structure of Fibre Glass Reinforce Plastics Bolt-End
Authors: Ma Nian Jie , Li Ying Ming , Zhang Zhi Jie
Published: March 2009

This article analyses the cutting mechanism of bolt-end according to coal side supporting. The authors put forward a new structure of FRP bolt-end by studying the structure of FRP bolt-end. The new structure is named as metal bushing and indentation. It is testified that the bolt with the structure can effectively support coal side in practice.
Study on the Electromagnetic Properties of Various Compositions of Magnesium-Copper-Zinc Ferrites
Authors: Hyie Koay Mei , Metselaar I.H.S.C. , Yaacob Iskandar Idris
Published: March 2009

Various compositions of magnesium-copper-zinc (MgCuZn) ferrites were prepared via a co-precipitation method for the development of ternary property-composition diagrams. The diagrams were used to investigate the effect of various main components (MgO, CuO and ZnO) on the electromagnetic properties of MgCuZn ferrites system. Four electromagnetic properties were measured. These are initial permeability, quality factor, loss factor and resistivity. Analysis of the diagrams indicated that high MgO content was associated with the deterioration of the electromagnetic properties. Too much CuO led to the formation of Cu-rich precipitates that were detrimental to the electromagnetic properties. High ZnO content was necessary to obtain good magnetic properties of the ferrites. Hence, it was suggested that good electromagnetic properties on MgCuZn ferrites were attributed to low MgO, moderate CuO and high ZnO contents.
Molecular Dynamics Simulation of Displacement Cascade in α-Zr
Authors: Takahashi Akiyuki , Hirose Kotoko , Soneda Naoki , Kikuchi Masanori
Published: March 2009

In this work, the point defect production in α-Zr at 600K by displacement cascade
with Primary Knock-on Atom (PKA) energy up to 20KeV has been investigated by molecular dynamics (MD) simulations. Especially, the influence of subcascades formation on the point defect and cluster production in 20keV cascades has been investigated in detail. The subcascade formation was seen in 36 cases of 20keV cascade simulations out of 50 cases. As the damaged areas are divided into many small areas, the maximum size of point defect cluster tends to decrease when the displacement cascade is settled. On the other hand, subcascades formation has not had an influence on the number of Frenkel pairs in final state of the 20keV cascades comparatively.
Investigation of Particle Size Effects on the Magnetic Properties and Corrosion Behaviour of Mechanically Alloyed Nd-Fe-B Powder
Authors: Jun H.K. , Yaacob Iskandar Idris
Published: March 2009

Elemental powders of Nd, Fe and B were mechanically alloyed using a planetary ball mill. The change of structure and particle size was examined. XRD pattern revealed that with prolong milling, the mixture of the powders was transformed to nearly amorphous state. Smaller particle size was observed with prolong milling. Magnetization of the mixture of powders was studied using AGM. The saturation magnetization of the mixture was observed to increase initially and then decrease with increasing milling time. The reduction of the magnetic properties was suspected to be due to surface damage which was incurred by extensive milling. The corrosion rate was observed to be higher for larger particle size (low milling time). This indicated higher mass gain percentage of larger particle size compared to lower particle size. The magnetic properties however, did not should any significant improvement after corrosion effect.
Osteogenic Potential of Tissue Engineered Bone by Combination of Marrow Mesenchymal Cells and Cultured Bone/Ceramic Constructs
Authors: Shigematsu Hideki , Yoshikawa Takafumi , Miyazaki Kazuhide , Satoh N. , Koizumi M. , Ueda Y. , Dohi Y. , Ohgushi Hajime , Takakura Yoshinori
Published: March 2009

Introduction: Osteogenesis occurs in porous hydroxyapatite (HA) when HA blocks combined with marrow mesenchymal cells are grafted in vivo. In vitro bone formation occurs in HA pores when HA combined with marrow cells is cultured in osteogenic medium containing dexamethasone. Cultured bone/HA constructs possess higher osteogenic ability when they are grafted in vivo. Marrow mesenchymal cells (MSCs) contain many stem cells which can generate many tissue types. In the present study, we investigated osteogenic potential of cultured bone/HA combined with MSCs. Materials and Methods: Marrow cells were obtained from the femoral bone shaft of male Fischer 344 rats (7 weeks old), and were cultured in T-75 flasks. Primary cultured cells were trypsinized and combined with porous HA (5x5x5 mm, Interpore 500). The composites were subcultured in osteogenic medium containing dexamethasone. One tenth of primary cells were transferred into new T-75 flasks containing standard medium. After 2 weeks, MSCs were trypsinized, combined with cultured-bone/HA constructs, and prepared for implantation. MSC/cultured-bone/HA constructs, cultured bone/HA constructs, and HA alone were subcutaneously implanted into syngeneic rats. These implants were harvested at 2 or 4 weeks post-implantation, and prepared for histological and biochemical analyses. Results: Alkaline phosphatase activity and osteocalcin content of MSC /cultured bone/HA constructs were much higher than those of cultured bone/HA constructs at 2 and 4 weeks post-implantation. Histological examination supported these findings. Discussion and Conclusion: MSCs show high ability of cell proliferation. In addition, MSCs can generate new blood vessels which would support regeneration of bone tissue. Here, we suggested that MSCs could promote osteogenesis. We also showed that excellent engineered bone tissue could be fabricated by combining MSCs and cultured bone derived from dexamethasone-treated MSC culture.
Porous Composite with Tunnel-like Interconnecting Pores of Hydroxyapatite with Magnetite Particles
Authors: Ioku Koji , Murakami Setsuaki , Atsumi Takashi , Jeyadevan Balachamdran , Ishida Emile Hideki
Published: March 2009

Porous composites of magnetite / hydroxyapatite with bimodal pore size distribution were prepared by hydrothermal method. Magnetite particles of about 1 µm in size with polyhedral shape were dispersed into hydroxyapatite porous matrix. The hydroxyapatite particles were rod-shaped crystals and the size of crystals were about 10 µm in length with the aspect ratio of over 25. Rod-shaped hydroxyapatite crystals were locked together to make micro-pores of about 0.8 µm in size. In addition, macro-pores of about 400 µm in size were prepared by our unique method. Hydroxyapatite in this composite was non-stoichiometric hydroxyapatite with calcium deficient composition. This composite must have the advantage of adsorptive activity and osteoconductivity, because the hydroxyapatite has many specific crystal surface and micro-pores. The composites of magnetite / hydroxyapatite must be suitable for the hyperthermia therapy of cancer in bones.
Electrovector Effect of Polarized Porous Hydroxyapatite Ceramics
Authors: Ikeda Chikako , Ueki Mikihiro , Nakamura Satoshi , Kobayashi Takayuki , Yamashita Kimihiro
Published: March 2009

Porous HA ceramics has been developed for the scaffold materials because the porous structure has been recognized to be necessary to invasion of body fluid and ingrowth of bone. The synthesized porous HA ceramics with several porosities were electrically polarized, and then the TSDC spectra were measured. The maximum electric current density and the stored polarization charges decreased with increasing the porosity. Therefore it was thought that the decreasing the
amount of proton of porous HA ceramics was one of the reasons of decreasing of the maximum electric current densities and the stored charges. The simulated body fluid (SBF) test implied that electrovector effects enhanced the apatite formabilities.
Adhesion, Proliferation and Morphology of Osteoblasts Cultured on Apatite Ceramics with Preferred Orientation to a-Plane
Authors: Miyazaki Akimitsu , Aizawa Mamoru
Published: March 2009

There are two crystal planes in hydroxyapatite (Ca10(PO4)6(OH)2; HAp) that is clinically applied to artificial bone or dental root. The two crystal planes, a- and c-planes, are anisotropy. We have successfully fabricated dense HAp ceramics with preferred orientation to a-plane from single-crystal apatite fibers (AF) and apatite gels (AG). We examined the cellular response, such as adhesion, proliferation and morphology, of orthoclastic MC3T3-E1 cells, to the surface of the HAp ceramics with preferred orientation to a-plane. The initial cell attachment efficiency of the HAp ceramics with a-plane was lower than that
of isotropic HAp ceramics as a control. This may be due to the difference of surface potential of the examined HAp ceramics. The proliferation of cells cultured on the HAp ceramics with a-plane was almost the same as that of isotropic HAp one.
Osteochondral Tissue Engineering Constructs with a Cartilage Part Made of Poly(L-lactic Acid) / Starch Blend and a Bioactive Poly(L-Lactic Acid) Composite Layer for Subchondral Bone
Authors: Ghosh S. , Viana Júlio C. , Reis Rui L. , Mano João F.
Published: March 2009

Articular cartilage has an inadequate natural rebuilding capacity. Tissue engineering has shown to have potential to provide an effective alternative to engineer the damaged cartilage. In this study, an integrated porous bi-layered scaffold was developed aiming to mimic the requirements of cartilage and underlying subchondral bone. The osteochondral approach explored in this work was to include
a common polymeric component in both cartilage and bone components, which maximised the integration at the interface by mean of a melt-based processing route. A blend of starch and poly(Llactic acid),PLLA, was used in the cartilage side, which was found to possess an adequate water uptake capability. For the bone region, to induce bioactivity, PLLA had been reinforced with
hydroxyapatite (HA) and bioactive glass (BG). The surfaces of the constructs were investigated as a function of soaking time in a simulated body (SBF) fluid using scanning electron microscopy (SEM) and FTIR. The SEM – FTIR indicated a bone-like apatite formation and the surface
coverage by apatite layer increased with increasing soaking time, whereas the cartilage-layer did not exhibit the formation of any apatite like layer.
High Cellular Biocompatibility of Calcium Carbonate / Poly (Lactic Acid) Composites Doped with Silicon
Authors: Obata Akiko , Maeda Hirotaka , Kasuga Toshihiro
Published: March 2009

Silicon-doped calcium carbonate / poly (lactic acid) composites (Si-CCPC) were estimated in cellular biocompatibility with culture tests using osteoblast-like cells (MC3T3-E1) and mesenchymal stem cells (MSC). The cellular biocompatibility of Si-CCPC was enhanced by coating with bone-like hydroxycarbonate apatite (b-HA) formed by simulated body fluid immersion. The b-HA was formed on Si-CCPC after 3-days of immersion and closely bonded with Si-CCPC. Numerous MC3T3-E1 and MSC showed good adhesion on the b-HA with extending their lamellipodia. The number of adhering MC3T3-E1 on Si-CCPC coated with the b-HA was higher than that on Si-CCPC. The b-HA has excellent biocompatibility and silicon is regarded to stimulate osteoblast and bone formation in vivo and vitro. The b-HA containing silicon on Si-CCPCis expected to enhance the cellular adheresion, proliferation and differentiation.
Evaluated of the γ-Ray Radiosterilized Cross-Linked PLLA and PLLA/HA In Vivo
Authors: Ohkawa Takashi , Nakamura Koushin , Itoman Moritoshi , Jin Feng Zhe , Hyon Suong Hyu , Tsutsumi Sadami
Published: March 2009

There are still some existing problems that are common to all absorbable materials; 1) It cannot be subjected to radiosterilization, 2) Sufficient strength cannot be maintained until the complete bone union is obtained. To solve these problems, PLLA and PLLA/HA were mixed with cross-bridge supplementary agent, Triallyl Isocyanurate (TAIC). Using these materials in vivo, we created and tested γ-ray radiosterilized absorbable bone fixation materials.
Effect of LiCl on Mechanics Property of HA Ceramics During Sintering
Authors: Jiang F.X. , Peng Qian , Liang Lie Feng , Weng Jie
Published: March 2009

Hydroxyapatite (HA) which has excellent biocompatibility and osteoconductivity is limited in the load-bearing repair because of its brittleness. Applying appropriate sintering additives for HA is a possible way to improve its mechanical properties. Systematic studies have has been performed to investigate the effect of LiCl as an additive on the microstructure and sinterability of HA and the relationship
to its mechanical properties. The densification of HA containing different LiCl contents was completed through a special sintering process with the highest temperature of 1280°C. Microhardness was tested as a short cut to evaluate the changes of mechanical properties affected by the microstructure of HA doped with
LiCl. The results of the experiment showed that LiCl is an effective sintering agent which causes neither decomposition of HA nor formation of other undesired phases with the increase of its microhardness.
Influence of Complex Frictional Heating and Mechanical Stress Effect for Surface Crystalline Structure Change of Zirconia Femoral Head
Authors: Ueno Masaru , Iwamoto Mikio , Ikeda Junji
Published: March 2009

Several clinical reports pointed out that the monoclinic transformation of crystalline structure of zirconia femoral head with clinical service time can cause the changes of surface roughness and mechanical properties. To elucidate the relationship between these surface roughness change induced by phase transformation and UHMWPE socket wear, hip simulator wear tests were performed on total hip prostheses (THP) up to 6 million cycles running. Four groups of different surface monoclinic phase fraction of Kyocera zirconia heads were prepared by aging treatment prior to the wear tests. The surface roughness/ wear rate of zirconia heads with 0, 10, 50 and 80mol% monoclinic phase fraction were 0.009/ 3.8, 0.014/ 3.9, 0.012/ 3.7 and 0.010µmRa/ 3.1mg/million cycles, respectively. These results exhibit that the surface roughness change induced by phase transformation does not significantly influence extent of the generation of UHMWPE debris in Kyocera zirconia /UHMWPE THP system. In contrast, the surface roughness exhibited complex relation with the monoclinic phase fraction and therefore the morphological analysis was performed on the zirconia articulating surfaces
Arthroplasty Using Ball-and-Socket Type Ceramic Prosthesis for the Osteoarthritis of the Trapeziometacarpal Joint of the Thumb
Authors: Suzuki Katsuji , Shibata Kunio , Shigemori Kanae , Ichinose Hirofusa , Tanaka Tohru
Published: March 2009

Six patients underwent arthroplasty of the trapeziometacarpal joint of the thumb with our ball-and socket type ceramic prosthesis for the osteoarthritis of Eaton stage 3 or 4. Our prosthesis was made of alumina ceramic and high-density polyethylene. Pain and dislocation or subluxation of the trapeziometacarpal joint were found in all of the patients preoperatively and these symptoms were relieved completely after surgery. The % total active motion of the trapeziometacarpal joint and metacarpophalangeal + interphalangeal joints, the % grip strength and % pinch strength improved postoperatively. The trapeziometacarpal joint function according to Eaton’s criteria after surgery was excellent of 5 patients and good of 1 patient.
Polarization Energy Effect of Electrovector Hydroxyapatite on Bonelike Crystal Growth in SBF
Authors: Nakamura Satoshi , Shinohara Keiichirou , Kieda Nobuo , Yamashita Kimihiro
Published: March 2009

An electrovector effect of the polarized hydroxyapatite (HA) on crystal growth in a
simulated body fluid was clarified to discuss the role of the polarization energy in the effect. The polarization of the HA carried out in high dc field at 300-600°C was confirmed by thermally stimulated depolarization current measurements. The dependence of the thickness of the crystal grown layer on the induced charge was remarkably indicated in the modification of the growth rates. The growth rate under an optimum polarization condition was estimated to be almost 3 times of that
by the biomimetic method. At the early stage of the crystal growth, the grown crystals were spherical and their sizes were dependent on the field strength and time for polarization. The polarization is therefore considered to effect the nucleation as well as the crystal growth.
Enhancing Bone Regeneration by Synthetic Peptide-Coated CMP Granules
Authors: Yoon D.H. , Kim H.J. , Lee J.H. , Cho M.J. , Shin Hong In
Published: March 2009

For effective bone regeneration, various surface modifications have been tried. In an effort to improve osteogenic repair potential, we evaluated recombinant peptides containing the RGD domain as a bioactive molecule for tissue-engineered bone regeneration. The synthetic peptides slightly suppressed cellular proliferation in the in vitro culture system but induced favorable osteoblastic differentiation, which was determined by MTT and ALP activity staining, respectively. The synthetic peptide coated CMP granules, which were implanted into the mandibular bone defects showed more favorable bone repair compared to the non-coated CMP implantation. In addition, there were not any sign of inflammatory reaction. These findings suggest that synthesized peptides containing the RGD domain enhance cellular attachment and osteogenic activity in vivo condition and that the peptide-coated CMP granules can serve as a biocompatible bone substitute.
Apatite-Forming Abilities of β-TCP and Hydroxyapatite Ceramics after Autoclaving
Authors: Obata Akiko , Kasuga Toshihiro
Published: March 2009

Bonelike apatite formation abilities of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were enhanced by a simple and useful method of autoclaving in distilled water. By immersion tests using simulated body fluid, the apatite formation was observed on the surfaces of the autoclaved β-TCP and HA after 10 days and confirmed to be controllable by the autoclaving temperature, although the formation was not or dispersedly observed on non-autoclaved samples. Surface potentials and morphologies of the samples were decreased and roughed after the autoclaving
Cytotoxicity of Various Calcium Phosphate Ceramics
Authors: Tamai Masato , Nakaoka Ryusuke , Tsuchiya Toshie
Published: March 2009

The cytotoxicity of five calcium phosphate ceramics, hydroxyapatite (HAp), flouroapatite (FAp), α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP) and tetracalcium phosphate (TTCP), was investigated. Based on the guidelines of biological test for medical devices in Japan, a cytotoxicity test of these calcium phosphates was carried out using Chinese hamster V79 lung fibroblasts. The cytotoxic study revealed that FAp and α-TCP showed high cytotoxicities. From various analyses, it was considered that the cytotoxicity of the FAp was due to fluorine ions extracted in a culture medium and the cytotoxicity of α-TCP resulted from a decrease in pH of the medium by the phosphoric acid, which produced by hydrolysis of( the α-TCP.
Real Time Neutron Diffraction Studies of Apatite Glass Ceramics
Authors: Stamboulis Artemis , Hill Robert G. , Calver Adam , Bubb N. , Manuel P.
Published: March 2009

Apatite-mullite glass-ceramics have been developed based on SiO2-Al2O3-P2O5-CaOCaF2 glasses. The glasses crystallise to form fluorapatite (FAP) and mullite with an appropriate heat treatment. The crystallisation mechanism has been thought to occur via a prior amorphous phase separation. The aim of this study was to carry out real time neutron diffraction of apatite-mullite glass-ceramics in order to develop an understanding of the crystal growth and crystal dissolution phenomena in the temperature regime between 550 and 1200oC. The results show that during the initial stages of fluorapatite crystallisation pronounced line broadening was observed indicating crystallisation on a nanoscale. Mullite starts to crystallise once there is insufficient charge balancing cations in the glass to maintain aluminium in a four fold coordination state. As a result of this work it is suggested that the mechanism of crystal growth of FAP is thought to involve the dissolution of smaller FAP crystals during the crystal growth temperature followed by re-crystallisation of FAP on the remaining larger crystallites during cooling.
Electrovector Effect of Polarized and Chemically Treated Na2O-CaO-P2O5-SiO2-Al2O3 Bioglasses
Authors: Sasaki Taketo , Kobayashi Masahiro , Nakamura Satoshi , Yamashita Kimihiro
Published: March 2009

Na2O-CaO-P2O5-SiO2-Al2O3 (NCPSA) glass was investigated in its electrical polarizability by complex impedance and thermally stimulated depolarization current (TSDC) measurements. Moreover, the NCPSA glass was also subjected to a chemical treatment for bioactivity improvement. The effects of the electrical polarization and the chemical treatment on apatite formability of NCPSA glass were investigated by immersion test using simulated body fluid. From the result of complex impedance measurements, the activation energies for electrical conductivities NCPSA glass was 1.1eV. From the TSDC measurements, the polarized NCPSA glass showed monotonically increasing curves in depolarization current density spectra. The stored electrical charge calculated from TSDC measurements of the NCPSA glass polarized with electrical dc field of 2kV･cm-1 at 600°C for 1h was 4.91 mC･cm-2. The NCPSA glass treated with 1M NaOH indicated apatite formability in SBF and exhibited bioactivity. We disclosed that the combination of electropolarization and chemical treatment changed the apatite formability of the NCPSA glass in SBF, consequently, improved the bioactivity of the glass.
Histological Evaluation of Percutaneous Device with Different Materials
Authors: Zheng L. , Yuan T. , Jiang Y.M. , Luo J.M. , Zhang Xing Dong
Published: March 2009

Biological sealing is a key factor for successful development of percutaneous device (PD). A new device with arc-perforated flange as subcutaneous part and groove-shaped percutaneous part, was intended to improve integration of soft tissue and implant. Material and surface properties are known to have great impact on tissue-implant integration. To understand how a material and its surface property can influence tissue reaction, and to find the appropriate material for PD fabrication, five different kinds of materials were prepared for in vivo animal tests with corresponding histological evaluation. Results revealed that a more stable junction was formed between the soft tissue and HA coated titanium implant than other combinations.
Preparation of Hollow Y2O3 Microspheres for In Situ Radiotherapy of Cancer by Enzymatic Reaction
Authors: Masakazu Kawashita , Takayama Yoshihisa , Kokubo Tadashi , Takaoka Gikan H. , Araki Norio , Hiraoka Masahiro
Published: March 2009

Chemically durable microspheres 20−30 µm in diameter containing a large amount of yttrium are useful for in situ radiotherapy of cancer as they can be activated by neutron bombardment to become β-emitters and can be injected in the vicinity of the cancer to provide a large localized dose of β-radiation. In this study, preparation of hollow Y2O3 microspheres using an enzymatic reaction was attempted, and the structure and chemical durability of the resulting microspheres were investigated. Hollow Y2O3 microspheres 20–30 &m in diameter were successfully prepared by this enzymatic method. The outer surface of the microspheres was smooth and dense, whereas the inner parts had a honeycombed structure. In simulated body fluids at pH 6 and 7, the hollow Y2O3 microspheres showed high chemical durability.
Hydroxyapatite/Chondroitin Sulfate Microparticles with Different Particle Size and its Adsorption Ability of Proteins
Authors: Watanabe Hajime , Ikoma Toshiyuki , Chen Guo Ping , Monkawa Akira , Tanaka M.
Published: March 2009

Hydroxyapatite/chondroitin sulfate (HAp/ChS) microparticles with the perfectly spherical shape and the averaged particle sizes of 4.1, 7.8, 19.9 and 29.4 µm were fabricated by a spray dry method under the different atomizing pressures and the concentrations of suspensions. The contents of ChS in the microparticles were varied at 1.49, 3.18, 7.82, 14.2 wt%, and the ChS elution rate in distilled water from the microparticles was increased with the increase of ChS contents. The adsorption isotherms of cytochrome C on the microparticles in 1/10 diluted phosphate buffer saline (PBS) were followed to the Langmuir’s equation regardless of the change of ChS contents, while those of catalase were not followed. The HAp/ChS microparticles can adsorb greater amount of cytochrome C than pure HAp microparticles, but less amount of catalase than pure HAp. The electrostatic interaction between the proteins and ChS was of great importance in the adsorption properties.
A Novel Synthesis of Nano-Fluoride-Substituted Hydroxyapatite Through Dialysis
Authors: Zhang Sheng Min , Zhou W. , Liu Jian , Cheng L. , Chen P.P.
Published: March 2009

A novel synthesis of nano-fluoride-substituted hydroxyapatite (nano-F-HAP) was successfully realized through dialysis process within 4 h, which required much shorter time than the methods reported so far. In new preparation, a dialysis was employed to purify unwanted ions. The removal efficiency of impurity ions in dialysis was evaluated by calculating the concentration of the representative irons NH4 + between the inner slurry and outer distilled water. Results showed that total dialysis efficiency came to 94.5%. The final products were characterized by XRD, HR-TEM, and FT-IR. The XRD and FT-IR results strongly supported substitution of F- for OH-, and the TEM pictures further indicated that the final crystals are about 100nm in length and about 20 nm in diameter without obvious aggregation. Therefore, comparing with traditional purifying processing, such a new synthesis provides a promising application for scale preparation of fine nano-F-HAP crystals.