bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Electro-Statically Driven Micro-Electro-Mechanical Systems
Authors: Cho Chong Du , Lee Byung Ha
Published: March 2009

In this paper, a methodology of modeling and simulating the electro-statically driven micro-electromechanical systems (MEMS) is presented, utilizing topography data with an arbitrary structure. In the methodology, the mask layout and process recipe of a device are first generated and the model then discretized by an auto-mesh generation for the finite element analysis. Finally the analysis is performed to solve the Laplace and the dynamic equation at a time. The methodology is applied to an electro-statically driven comb-drive as a test vehicle for verification.
Experimental Investigation on the Structural Behavior of Shear Connectors Used in the FRP and Concrete Bridge Deck System
Authors: Joo Hyung Joong , Lee Seung Sik , Yoon Soon Jong , Park Ju Kyung , Youn Seok Goo
Published: March 2009

Feasibility study on the use of newly developed FRP and concrete composite bridge deck system is conducted. To lengthen the service life of bridge deck, the steel-free bridge deck system is developed. In this deck system, shear connectors between FRP module and concrete are utilized and structural behavior of shear connectors is investigated experimentally. The result of an investigation reveals that the system is promising.
General Solving Method of Energy Dissipation Rate of Deforming Region in Upper-Bound Analysis for Coulomb Material
Authors: Cui X.Z. , Jin Q. , Shang Q.S. , Yao Zhan Yong
Published: March 2009

At present the energy dissipation rate per unit volume of deforming region is expressed with the function of principal strain rates in upper-bound analysis for Coulomb material and this restricts the application of deforming failure mechanisms in upper-bound method. In this paper, a general method of expressing the energy dissipation rate of deforming region with bulk strain rate was
put forward and the conditions that the assumed velocity field of deforming region should meet were pointed out. The general method simplifies the solving process of the energy dissipation rate. Finally, the method was employed to calculate the energy dissipation rate of the logspiral shear zone and was proved practical.
Effect of Shear Stress and Displacement on the Hydraulic Properties of a Marble Fracture with Sand
Authors: Liu Cai Hua , Chen Cong Xin , Feng Xia Ting
Published: March 2009

A test apparatus was developed to study shear-flow coupling properties for a marble fracture with sand. Experimental tests include shear stress-flow coupling process and shear displacement-flow coupling process. The shear stress-flow coupling test results, revealed that mechanical aperture keeps constant during shear, and that hydraulic aperture and conductivity decrease almost linearly with increasing shear stress. The shear displacement-flow coupling test results showed that hydraulic behavior under shear displacement includes two phases. During the first about 0.05mm shear displacement, hydraulic aperture and conductivity decrease with increasing shear displacement, and mechanical aperture remains constant or increases only by several microns of magnitude. After shear displacement is up to about 0.05mm, the fracture dilates remarkably, and hydraulic aperture and conductivity increase with shear displacement increasing.
The Application of Hydraulic Fracturing in Storage Projects of Liquefied Petroleum Gas
Authors: Feng Jing , Sheng Qian , Luo Chao Wen , Zeng Jing
Published: March 2009

It is very important to study the pristine stress field in Civil, Mining, Petroleum engineering as well as in Geology, Geophysics, and Seismology. There are various methods of determination of in-situ stress in rock mass. However, hydraulic fracturing techniques is the most convenient method to determine and interpret the test results. Based on an hydraulic fracturing stress measurement campaign at an underground liquefied petroleum gas storage project which locates in ZhuHai, China,
this paper briefly describes the various uses of stress measurement, details of hydraulic fracturing test system, test procedure adopted and the concept of hydraulic fracturing in arriving at the in-situ stresses of the rock mass.
A Study of Leakage Magnetic Flux Detector Using Hall Sensors Array
Authors: Lee Jin Yi , Hwang Ji Seoung , Lee Kyung Chul , Choi Se Ho
Published: March 2009

It is important to estimate a magnetic field’ intensity distribution for the application of to industrial nondestructive evaluations. A magnetic camera provides the same spatial resolution and a distribution of a quantitative magnetic field with homogeneous lift-off. The method for arraying sensors is important on the magnetic camera because it must obtain a high spatial resolution. This work proposes an equation to evaluate the limitation of spatial resolution on the condition of the decided size of a magnetic sensor package. The possibility of obtaining the high spatial resolution in spite of the above-mentioned limitation would also be verified.
Impact Perforation of Stiffened Steel Plates by Rigid Projectiles
Authors: Ning Jian Guo , Song Wei Dong , Cheng Wang , Wang Jing
Published: March 2009

An experimental program has been conducted to study the perforation of stiffened steel plates by truncated oval-nose projectiles at normal impacts. The projectiles of 104mm diameter were fired at 921A stiffened plates with thickness 15.mm for the base plate at an initial velocity from 560m/s to 620m/s. High speed camera system was employed to record the perforation process and from the digital images, impact angles and projectile velocities during perforation were determined using image processing. Numerical simulations have been performed for projectiles against single and layered plates adopted in the experiments. The perforation process is explored in details and the deformation modes are obtained. By adopting an energy method, a four-stage analytical model that accurately predicts the residual velocity is developed. Simulation results, experimental data and theoretical predictions are reasonably well correlated.
Nonlinear Analysis of Pressurized Piping Elbows Subjected to Out-of-Plane Bending
Authors: Lubis Asnawi , Akmal Jamiatul
Published: March 2009

The behavior of piping elbows under bending and internal pressure is more complicated than expected. The main problem is that the coupling of bending and internal pressure is nonlinear; the resulting stress and displacement cannot be added according to the principle of superposition. In addition, internal pressure tends to act against the effect caused by the bending moment. If bending moment ovalise the elbow cross-section, with internal pressure acting against this deformation, then the ovalised cross section deform back to the original circular shape. It is then introduced the term “pressure reduction effect”, or in some literature, “pressure stiffening effect”. Current design piping code treats the pressure reduction effect equally for in-plane (closing and opening) moment and outof- plane moment. The aim of this paper is to present results of a detailed finite element analysis on the non-linear behavior of piping elbows of various geometric configurations subject to out-of-plane bending and internal pressure. Specifically the standard Rodabaugh & George nonlinear pressure reduction equations for in-plane closing moment are checked in a systematic study for out-of-plane moment against nonlinear finite element analysis. The results show that the pressure stiffening effects are markedly different for in-plane and out-of-plane bending.
Developing Reinforced Concrete Elastic-Plastic Beam Element Model
Authors: Zhang Li , Liu Zhan Li , Zhuang Zhuo , Kanayama T.
Published: March 2009

The response analysis of reinforced concrete (RC) structures subjected to strong earthquake motions require realistic conceptual models. The special models, such as Clough and Takeda, which describe the non-linear section characteristic of reinforced concrete beam and column. In the earthquake motions, the deforming is sensitive to the response of structures intensively. The traditional lumped plastic model inevitably induces inaccuracy. Hence, meshing the members or distributing stiffness along the whole member is employed to simulate the seismic response of the structures. In this paper, Takeda elastic-plastic beam element model has been developed, which is based on general FEM code ABAQUS in order to simulate the response of RC. The influence is discussed due to the different lengths of plastic zone and element sizes.
Adaptive FEM Analysis Technique Using Multigrid Method for Unstructured Hexahedral Meshes
Authors: Wada Yoshitaka , Shinbori Jun'ichi , Kikuchi Masanori
Published: March 2009

MG (multigrid) method is one of the most promising solvers for large scale problems. Hexahedral mesh generation and its adaptation are not enough to use for practical applications, because its mesh generation is very difficult and still labor intensive work by hand. We have developed hexahedral local refinement technique controlled by posterior error estimation. We have proposed a MG technique for unstructured hexahedral meshes with local mesh refinement. In this paper, the proposed technique is evaluated to check its performance and severe analyses of bending cantilevers. Performance of MG for unstructured hexahedral meshes is compared with that of the PCG (preconditioned conjugate gradient) through several benchmark examples of 3-D static elastic analysis. Proposed MG is faster than PCG for all problems as number of freedoms increases. Finally limitation of the proposed technique is presented.
Utilization of Numerical Techniques to Predict the Thermal Behavior of Wood Column Subjected to Fire. Part A: Using Finite Element Methods to Develop Mathematical Model for Wood Column
Authors: ElShayeb Mohamed , Malik Abdul Rashid Ab , Ideris Fazril , Hari Zolman , Razak Norhaida Ab , Siang Jacqueline Eng Ling , Anuar Zulfika
Published: March 2009

The mathematical model to predict the temperature history for wood column is needed in order to determine its fire resistance when exposed to fire. In this paper, an intelligent methodology called Finite Element Method (FEM) of performing analysis for the square and circular wood columns by virtually or artificially developing a temperature history mathematical model. Numerical simulation model has been developed for the wood column by using two-dimensional mathematical model. The two-dimensional mathematical model was developed by using Galerkin’s Weighted Residual technique. This model focuses on the regional material of the wood column for describing its thermal behavior. When the temperature history in a column and relevant materials properties are known, the strength of the column can be calculated at any time during fire. Therefore, the development of the temperature history mathematical model is a must before any
further study to be carried out for the wood columns. The flow of convection will result in minimal increase in the rate of heat energy reaching the column core. The analysis shows that the temperature of the column increases with respect to the duration of exposure to fire.
A Simplified Linear Consistency Kernel Function in SPH Method
Authors: Xu Fei , Kikuchi Masanori
Published: March 2009

Smoothed Particle Hydrodynamics (SPH) is a relatively new technique for simulating the dynamic response of solids, especially for high velocity impact and fracture problem. However, closer examination of SPH reveals some severe problems. The major difficulties are: (1) tensile instability; (2) zero-energy mode; (3) boundary deficiency; (4) less accuracy. One solution to these major difficulties with SPH is to improve the consistency of the kernel function. Based on the Reproducing Kernel Particle Method (RKPM), the concept of the proposed simplified linear consistency is introduced. The most attractive feature of the simplified linear consistency is the ease and cheapness of doing 3D calculation. One contribution of this paper is to show clearly the accuracy of solution gradually improved by increasing the order of the consistency. Simple 3D impacting models are established with different geometries and higher accurate results are obtained by using higher consistency kernel functions. Other features as numerical convergence, computational efficiency, etc. and some considerations of the simplified linear consistency kernel function are also discussed.
Probabilistic Fracture Mechanics Analysis for Optimization of Sub-Sea Gas Pipelines Inspection
Authors: Sadikin Indera , Suharto Djoko
Published: March 2009

The dynamic nature of marine environment is the major cause of fatigue failures in subsea gas pipeline structures. Since the severest loaded part of piping system is the free span, freespan inspection is performed periodically to ensure that no free span exceeds its critical length. The objective of this paper is to optimize free-span inspection interval by means of probabilistic fracture mechanics analysis. Simulation data is taken from previous work of Tronskar [1]. Stress intensity factors at the crack tip are calculated by crack closure technique. Fatigue crack growth is simulated by cycle-by-cycle integration technique. The fracture mechanics analysis is then expanded to probabilistic analysis to include stochastic input parameters. Probability of failure is computed by modified direct simulation method. Based on the result of direct simulation, the studied pipelines are recommended to be inspected every 3 years to make sure that no free span exceeds 30 m.
Study on Ballistic Energy Absorption of Laminated and Sandwich Composites
Authors: Cui Xiao Dong , Zeng Tao , Fang Dai Ning
Published: March 2009

The impact response and energy absorbing characteristics of laminated, foam sandwich and honeycomb sandwich composites under ballistic impact have been studied in this investigation. An improved model is proposed in this paper to predict the ballistic property of the laminated composites. In this model, the material structures related to fiber lamination angles are designed in terms of their anti-impacting energy absorption capability. The ballistic limit speed and energy absorption per unit thickness of the three composites under different conditions are calculated. It is shown that honeycomb sandwich composite has the best ballistic resistance capability and energy absorption property among the three composites.
Bending Performance Analysis of Aluminum-Composite Hybrid Tube Beams
Authors: Lee Sung Hyuk , Kim Hyung Jin , Choi Nak Sam
Published: March 2009

Bending deformation and energy absorption characteristics of aluminum-composite hybrid tube beams have been analyzed for improvement in the bending performance of aluminum space frame by using experimental tests combined with theoretical and finite element analyses. Hybrid tube beams composed of glass fabric/epoxy layer wrapped around on aluminum tube were made in autoclave with the recommended curing cycle. Basic properties of aluminum material used for initial input data of the finite element simulation and theoretical analysis were obtained from the true stress-true strain curve of specimen which had bean extracted from the Al tube beam. A modified theoretical model was developed to predict the resistance to the collapse of hybrid tube beams subjected to a bending load. Theoretical moment-rotation angle curves of hybrid tube beams were in good agreement with experimental ones, which was comparable to the results obtained from finite element simulation. Hybrid tube beams strengthened by composite layer on the whole web and flange showed an excellent bending strength and energy absorption capability.
Assessment of Fiber Stress Based on Elastoplastic Analysis in Discontinuous Composite Materials
Authors: Kim Hong Gun
Published: March 2009

An elastopalstic analysis of the micromechanical approach is performed to investigate the stress transfer mechanism in a short fiber reinforced composites. The model is based on the New Shear Lag Theory (NSLT) which was developed by considering the stress concentration effects that exist in the matrix region near fiber ends. The unit cell model is selected as the Representative Volume Element (RVE) for the investigation of longitudinal elastoplastic behavior in discontinuous
composites. Thus far, it is focused on the detailed description to predict fiber stresses in case of the behavior of elastoplastic matrix as well as elastic matrix. Slip mechanisms between fiber and matrix which normally take place at the interface are considered for the accurate prediction of fiber stresses. Consequently, onset of Slip points is determined analytically and it showed a moving direction to the fiber center region from the fiber tip as the applied load increases. It is found that the proposed model gives the more reasonable prediction compared with the results of the conventional model (SLT).
Mechanical Properties of GFRP Laminates Manufactured by Process Combined with Wet Lay-Up and Vacuum Curing
Authors: Kook Joong-Suk , Adachi Tadaharu
Published: March 2009

In this study, a manufacturing process for glass fiber reinforced plastics (GFRP) laminates was developed to improve volume fraction of fibers and mechanical properties. The manufacturing process is combination with wet lay-up and vacuum curing under atmosphere pressure for production of large and complicated structure as a leisure boat and so on. Several kinds of GFRP laminates were produced to consider optimum conditions of the process from viewpoint of volume fraction of fibers and mechanical properties. Volume fractions of fibers in GFRP laminates were measured and cross sections were observed by an optical microscope. The volume fraction in the GFRP laminate made by the suggested method was improved to 41 %, although the one made by conventional wet lay-up method was 17.7 %. Because a lot of large voids included in the laminates were drastically decreased due to the methods. For each laminate, three-point bending test was performed to measure elastic modulus and fracture toughness. Elastic modulus was improved from 5.39 GPa to 8.91 GPa with high volume fractions of fibers. Fracture toughness was improved from 8.19 MPa m1/2 to 16.6 MPa m1/2. Therefore, it was obtained that the method combined with wet lay-up and vacuum curing is easy process for manufacturing large and complicated structure to improve excellent mechanical
properties and accuracy of structural shape.
Effects of Electric Fatigue on Piezoelectric Ceramics
Authors: Lee Kwok Lun , Soh Ai Kah
Published: March 2009

The fatigue behavior of piezoelectric ceramics PZT-5 subjected to three-point bending was investigated under a cyclic electric load coupled with a constant mechanical load. The direction of poling was perpendicular to that of the mechanical load. The fatigue life curves under high and low electric loading were compared. Non-linear relationship was observed between dS/dN and E/Ec.
The Effect of Cr & Cu on the Fatigue Strength of Grey Cast Irons
Authors: Suprihanto Agus , Harsokoesoemo Darmawan , Suratman Rochim
Published: March 2009

The mechanical properties of grey cast irons can be modified with alloying elements. Cr and Cu have been known as elements that can improve tensile strength of grey cast irons. The improvement of tensile strength can be influence of fatigue strength. The goal of this research is to study the effect of alloying Cr and Cu on the fatigue strength. Four materials of grey cast irons have been conducted to high cycle fatigue (HCF) testing on the rotating bending machine. The first material is grey cast irons without added Cr and Cu, and the other have added. The percentages of Cr have been added are 0,23% wt, 0,32%wt and 0,47%wt and Cu 0,6%wt to 0,7%wt. The metallography examinations and tensile test also have been conducted. The results of this research are the material has the same microstructure. The microstructures of its materials are pearlitic grey cast irons with graphite type VII, distribution A and size of graphite 3-5. The tensile, endurance and fatigue strength of materials, which added Cr and Cu significantly increasing, compared with base
materials. The tensile strength rose from 191MPa to 232MPa and the endurance strength raised from 94 MPa to 110MPa. However three modified materials, which added Cr and Cu has the same effects.
Bone Regeneration from Frozen Marrow Mesenchymal Cells/Recombinant Human Bone Morphogenetic Protein/Hydroxyapatite Transplantation
Authors: Miyazaki Kazuhide , Yoshikawa Takafumi , Iida Jin , Ueda Y. , Koizumi M. , Satoh N. , Shigematsu Hideki , Dohi Y. , Ohgushi Hajime , Takakura Yoshinori
Published: March 2009

Introduction: Marrow mesenchymal cells contain stem cells and can regenerate tissues. We previously reported the clinical application of autologous cultured bone to regeneration therapy. However, in cases with low numbers of active cells, culture is often unsatisfactory. If frozen marrow cells retain their osteogenic potential, we could clinically use them in regeneration therapy as alternatives to high active cells obtained from youngsters. Here, we examined osteogenic potential of
frozen human mesenchymal stem cells in combination with recombinant human bone morphogenetic protein (rhBMP) using biochemical and histological analyses. Method: Marrow fluid was aspirated from the human iliac bone of a 46-year-old man with lumbar canal stenosis during surgery. Two weeks after primary culture in standard medium, bone marrow mesenchymal stem cells (BMSCs)
were trypsinized for the preparation of a cell suspension, and cells were concentrated to 106 cells/ml by centrifugation. Cells were kept at – 80 °C until use. To impregnate porous hydroxyapatite (HA) with rhBMP, 1 3g rhBMP/20 3l 0.1 % trifluoroacetic acid was applied on HA, and then desiccated
under vacuum. In the present study, we used 4 subgroups: BMSC/rhBMP/HA, BMSC/HA, rhBMP/HA, and HA only. HA constructs from the 4 subgroups were implanted at subcutaneous sites on the back of 5-week-old nude mice (BALB/cA Jcl-nu). Eight weeks after implantation, implanted HA constructs were harvested, and biochemical and histological analyses were performed. Alkaline
phosphatase activity (ALP) and human osteocalcin (hOs) levels were measured. Results and Discussion: ALP activity and hOs in the BMSC/BMP/HA subgroup were 2 or 3 times that in the BMSC/HA subgroup. Histological analysis showed that significant bone formation was observed in
these two subgroups, and supported biochemical data. However, in the BMP/HA and HA only subgroups, significant bone formation could not be detected histologically nor biochemically. These results indicated that a combination of rhBMP and BMSCs, and only with a minimal amount of 1 3g rhBMP, allowed successful generation of human bone. In the human body, rhBMP in the order of
milligrams is necessary for bone formation. However, by combining BMSCs, HA and rhBMP, only a small amount of rhBMP was needed to dramatically enhance osteogenic potential. As we reported here, cryopreserved BMSCs also showed high osteoblastic activity. In conclusion, this study provided
histological and biochemical evidence that combination of cryopreserved BMSCs, BMP, and porous HA could enhance osteogenic potential.
Syntheses of Silicon-Containing Apatite Fibres by a Homogeneous Precipitation Method and Their Characterization
Authors: Aizawa Mamoru , Patel Nelesh , Porter Alexandra E. , Best Serena , Bonfield William
Published: March 2009

Silicon-containing apatite (Si-HAp) fibres were successfully synthesized by a
homogeneous precipitation method. The resulting Si-HAp fibres were composed of
carbonate-containing apatite fibres with preferred orientation in the c-axis. The Si contents in the Si-HAp fibres could be controlled by the Si concentration of the starting solutions. TEM observation indicated that the Si-HAp fibres were of single crystal. The Si-HAp fibres have potential as novel materials for high-performance biomedical devices.
Biological Evaluation of a Laminin–Apatite–Polymer Composite for Use in Skin Terminals
Authors: Oyane Ayako , Hyodo Koji , Uchida Masaki , Sogo Yu , Ito Atsuo
Published: March 2009

An ethylene-vinyl alcohol copolymer (EVOH) film with a laminin–apatite composite layer on its surface showed improved adhesion and compatibility to living epithelial tissue compared to untreated EVOH film. This result can be attributed to the good biocompatibility of apatite and the cell-adhesion activity of the laminin on the EVOH surface. This composite material, consisting of laminin, apatite, and EVOH, is considered a promising material for skin terminals to prevent epidermal downgrowth.
Effect of Dopant on Phase Stability of Zirconia in Hot Water
Authors: Naka Yukihisa , Takigawa Yorinobu , Higashi Kenji
Published: March 2009

The effect of cation dopant on tetragonal to monoclinic (t-m) phase transformation of zirconia is examined, which causes the degradation of zirconia in vivo. The transformation behavior is much different depending of the dopant. The transformation is promoted when the pentavalent element is added. In contrast, the transformation is suppressed when the bivalent element is added. In case the tetravalent element is added, the transformation is promoted if the ionic radius of the element is larger than that of zirconium, and that is suppressed if the element with smaller ionic radius is added. The valence and the ionic radius of dopant must be important factors for the phase stability of zirconia.
Improvements of Wear Properties DLC Coated UHMWPE and PMMA for Biomaterial
Authors: Kobayashi S. , Ozeki K. , Hirakuri K.K. , Aoki Hideyuki
Published: March 2009

Diamond-like carbon (DLC) films were deposited onto UHMWPE and PMMA substrates using plasma CVD process. To improve adhesion of DLC films, substrates were treated plasma before DLC deposition. Samples were analyzed by ball-on disk tester, atomic force microscopy (AFM), and scratch test. Wear and scratch resistance of DLC-coated each substrates were evaluated and showed good results.
A Comparative Study of Thai and Australian Crocodile Bone for Use as a Potential Biomaterial
Authors: Lewis Kanthi , Boonyang U. , Evans L. , Siripaisarnpipat S. , Ben-Nissan Besim
Published: March 2009

This study aims to characterize the structure and properties of crocodile bone to assess the potential for use in biomedical applications. Crocodile bone samples obtained from Thailand (Crocodylus siamensis) and Australia (Crocodylus porosus), being the tail and the tibia respectively, were treated to remove organic material and the inner spongy (trabecular) material. The dense cortical bone was used for comparative instrumental analyses. Specific comparisons were made against bovine cortical bone and pure synthetic hydroxyapatite. The material was then analyzed using simultaneous differential thermal analysis/thermogravimetric analysis (DTA/TGA), Fourier- Transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). Imaging of full bone samples was also conducted using an environmental scanning electron microscopy (ESEM).
The SEM provided valuable information through the imaging of samples, showing a markedincrease in bone porosity for crocodile material when compared to bovine samples. The crystallinity and/or crystallite size of carbonated hydroxyapatite has been found to be lower than synthetic apatite, with the tibia being the least crystalline of the bone types studied. The crystallinity index (CI) is used as a measure of crystallite size and internal strain. The strain is affected by substitutions
in the structure and these results provide a starting point for comparison of the resulting mechanical properties. There is a need for any biomaterial chosen for bone replacement to allow adequate osteointegration. Thus the study this far shows that crocodile bone is a very promising source of carbonated apatite for biomedical applications.
Stress Analysis and Optimizing of Osteoinductive Ca-P Ceramics and Net-Cage-Structured Titanium Alloy in Dog Segmental Femoral Defect Reparation
Authors: Bao C.Y. , Zhang Y.Z. , Wang H.L. , Luo J.M. , Tan Yan Fei , Fan Hong Song , Zhang Xing Dong
Published: March 2009

The purpose of this study was to develop a feasible technique for bone reparation and further explore the possible applications of Ca-P ceramics in segmental load-bearing bone reparation. HA/TCP ceramics sintered at 1250oC were fabricated into tube-like columns of Φ15mm×30mm with a central canal of Φ4mm. Bone-like apatite was precipitated on the ceramics before implantation. 12 male dogs were used in this study, and a 30mm long segmental bone defect was made in the middle of one femur of each dog. Supported by the fixation of net-cage-structured TC4, the osteoinductive Ca-P ceramic cylinder was used to repair the segmental defect in dog femur. Stress was analyzed by ANSYS. The morphology recovery, function restoration, gait analyses and bone regeneration were evaluated. After implantation at 2, 4 and 8 months, the specimens were harvested respectively. The specimens were evaluated with morphological observation and mechanical testing. Stress analysis showed that the thickness of TC4 net cage was 0.3mm. The morphology recovery of the experimental animal was good and function was restored after 2 months gradually. Aided by stress analysis and by optimizing the design and fixation of implants, Ca-P materials with excellent osteoinductivity could be applied in repairing segmental bone defects.
A Comparative Study Between Dynamic and Static Simulated Body Fluid Methods
Authors: Chen Ji Yong , Duan You Rong , Deng Chun Lin , Zhang Qi Yi , Zhang Xing Dong
Published: March 2009

In vitro method has often been used in the biodegradation/bioactivity evaluation of bioactive ceramics for its convenience and saving in time and outlay. The simulated body fluid (SBF) suggested by Kokubo was a good simulation of the osteoproduction environment in osseous tissue and has been proved to be a good method to study the bioactivity of biomaterials and the mechanism of bone bonding. But SBF is not a suitable method to research the osteoinduction of biomaterials. The results from SBF were not consistent with that from in vivo in muscle. The local ion concentration is the key factors to affect the nucleation and growth of apatite. In muscle the effect of body fluid flowing on local ion concentration cannot be ignored. A dynamic SBF suggested by these authors of this paper not only simulated the ion concentration of body fluid, but also simulated the effect of body fluid flowing on the local ion concentration near the surface or in biomaterials in muscle. The results from the dynamic SBF were in good agreement with that of the implantation experiments in muscle. The results from dynamic SBF showed that apatite only formed on the walls of macropores of the porous CaP, no apatite formed on the surface of both dense and porous CaP. The new bone only formed on the walls of macropores of porous CaP implanted in muscles, no apatite or osseous tissue could be found on the surfaces of both porous and dense CaP. The dynamic SBF preferably simulated the osteoinduction environment in non-osseous tissue and can be used in osteoinductivity evaluation of bioceramics.
Observation of Newly Formed Bone Around Dental Implants Using Parametric X-ray
Authors: Nakada Hiroshi , Sakae Toshiro , Suwa Taketoshi , LeGeros Racquel Z. , Gunji Atsuko , Kato Takao , Kobayashi Kihei
Published: March 2009

The purpose of this study is to determine the potential of the LEBRA-PXR imaging in investigating the details of newly formed bone around the dental implants. Transmission image observation of the undecalcified specimen at the wavelength of 1.771 Å showed clearly the formation of immaturely calcified new bone around the dental implants which could not be observed in the usual CMR nor conventional X-ray imaging apparatus.
Study on the Bioactivity of Anodic Oxidized Titanium Alloy Induced by Alkali Treatment
Authors: Zhao Ying , Xiong Tian Ying , Li Tie Fan , Wu J. , Jin Hua-Zi , Wang Li Bin
Published: March 2009

Alkali treatment induced to form bonelike apatite layer on the surface of the anodic
oxidized Ti6Al4V in 1.5 SBF. It was observed that some spherical apatite crystals were deposited on the surface of the sample for only 1 d. They gradually grew to cover the whole surface of the sample with further increasing soaking time. After 7 days of soaking in 1.5 SBF, apatite covered all the surfaces of the titanium alloys, and they packed very densely and uniformly. At the same time, large amount of new-formed apatite nuclei occurred on the first layer of apatite. The EDS and XRD
results proved that all the new-formed phases were composed of apatite. Mechanism of the bioactivity of the anodic oxidized titanium alloys was related to the Ti-OH group formation, and the Ti-OH group would induce apatite formation in SBF.
Effect of Acid Etching on Surface Chemistry and Microstructure of HA and CMP Grit-Blasted Ti Surface
Authors: Haryadi A.W. , You Chang Kuk , Kim Shin Yoon , Park Eui Kyun , Kim Kyo Han , Kim Suk Young
Published: March 2009

Grit blasting using bioactive HA and biodegradable CMP followed by acid etching has
been done. HNO3 and H3PO4 were used for the etching solution by controlling the concentration and etching time to know the effect on the surface chemistry and morphology of the Ti implant. Characterization of samples was done by using SEM, EDX and surface profilometer. The contents of residues on Ti surface decreased with increasing acid concentration and etching time. It was observed that the acidic etching rate of HA grits on Ti surface was faster than that of CMP grits. And HNO3 etched more rapidly the HA and CMP grits on Ti surface, compared to H3PO4.
Therefore, the surface roughness of dental implants can be controlled by having appropriate combination of acid concentration and etching time.
In Vitro Mineralization and Cell Adhesion on Surface Modified Poly (2 - hydroxy ethyl methacrylate-co-methyl methacrylate
Authors: Sailaja G.S. , Kumari T.V. , Yokogawa Yoshiyuki , Varma H.K.
Published: March 2009

Poly(2-hydroxyethyl methacrylate-co- methyl methacrylate) HM, was synthesized by free radical copolymerization, cross-linked with ethylene glycol dimethacrylate and phosphorylated. The phosphate coupling was ensured by ATR spectroscopy. The in vitro mineralization ability of the phosphorylated HM (designated as PHM) was investigated by studying the nucleation and growth
of calcium phosphate on its surface by immersing in simulated body fluid (SBF) solution. The coating morphology was studied by SEM and the Ca/P ratio of the coating by EDX analysis. The cell adhesion behaviour of PHM was studied by seeding Human osteosarcoma (HOS) cells for one week followed by SEM analysis along with HM as control. It was observed that HOS cells
exhibited biomineralization of calcium phosphate on the surface of HM as well as on PHM with a significantly higher amount on the surface of PHM as observed by von kossa staining method. The results show that PHM is capable of in vitro mineralization under simulated physiological condition, promotes cell adhesion by providing an excellent cell friendly surface and it exhibits
biomineralization of calcium phosphate in presence of HOS cells.
Osteogenic Differentiation of Human Bone Marrow Stromal Cells Cultured on Hydroxyl Carbonate Apatite Layer Preformed on Poly (ε-aprolactone)–Organosiloxane Nano-Hybrid Materials
Authors: Yoo Jeong Joon , Kim Hee Joong , Rhee Sang Hoon
Published: March 2009

Previous study showed that the novel poly(ε-caprolactone)–organosiloxane nano-hybrid material (SiOPCL) had bioactivity, biodegradability, and mechanical properties comparable to those of human cancellous bone. In this study, hydroxyl carbonate apatite layer (HCA) was preformed on the surface of SiOPCL, which mimicked the events likely to occur in vivo, and cellular behaviors of
human bone marrow stromal cells (hBMSCs) were investigated during the osteogenic differentiation on its surface (SiOPCL/HCA). Initial attachment, proliferation, and ALP activities of hBMSCs were comparable to those on tissue culture plates (TCPs), while the calcium content in the cell layer showed significantly higher value. It means that this novel bioactive nano-hybrid material
is likely to be a promising candidate for bone grafting materials because of good hBMSCs responses as well as apatite forming ability in the simulated body fluid.
Sterilization and Deodorization of Titanium Oxide and Hydroxyapatite Coating by Sputtering Technique
Authors: Janurudin Juliana M. , Ozeki K. , Aoki Hideyuki , Fukui Y.
Published: March 2009

TiO2 and HA thin film double coating has been proposed. The TiO2/HA thin film was coated on the glass by a Radio Frequency magnetron sputtering, and the characteristic of the thin film has been studied. The absorption of Formaldehyde (HCHO) gas in the TiO2/HA thin film was detected by gas chromatography, and the sterilization of Escherichia coli (E. coli) was evaluated in the antibacterial test. In the deodorization test, HCHO gas remained 0[%], 11[%] and 85[%] for TiO2/HA thin film, TIO2 thin film and thin film respectively. The sterilization result shows that E. coli for TiO2/HA thin film and HA thin film decreased 89[%] and 75[%] respectively.
Setting Kinetics Observation of a Brushite Cement by FTIR and DSC
Authors: Hofmann M.P. , Young A.M. , Nazhat Showan N. , Gbureck Uwe , Barralet J.E.
Published: March 2009

Time resolved infrared spectroscopy (FTIR) and isothermal differential scanning
calorimetry (DSC) were used for the first time to monitor the chemical reaction in a fast setting brushite forming calcium phosphate cement. It was found that the reaction percentage at a given time was dependent on temperature and not powder to liquid (P/L) ratio. Both methods showed that there was, within the temperature range investigated, a single autocatalytic like setting reaction
within the cement paste. Final conversion of the reactants was found to be unaffected by temperature and P/L ratio.
Calcium Phosphate Microspheres for Localised Delivery of a Therapeutic Enzyme
Authors: Barrias C.C. , Ribeiro C.C. , Martins M.C.L. , Barbosa Mario A. , Rodrigues D. , Sá Miranda M.C.
Published: March 2009

The ability of calcium titanium phosphate (CTP) and hydroxyapatite (HAp) microspheres to reversibly adsorb the enzyme glucocerebrosidase (GCR) while preserving its biological activity, and efficiently deliver it to Gaucher disease (GD) fibroblasts was investigated. CTP microspheres adsorbed ca. 3.6-fold more GCR than HAp microspheres. The activity of adsorbed GCR was higher
than the free enzyme in the case of CTP microspheres and lower when HAp was used. GCR release from both types of microspheres was characterized by the initial elution of a large percentage of enzyme followed by a delayed release that extended for at least 30 days. Released GCR was internalized by GD fibroblasts increasing their intracellular enzymatic activity. In cells treated with the same amount of GCR-loaded CTP microspheres or free-GCR a higher intracellular activity was
detected in the former case, suggesting an improved efficacy.
Effects of Crude Bone Morphogenetic Protein and Pulp-Capping Materials on Rat Dental Pulp Cell Proliferation and Calcification In Vitro
Authors: Ando Kimitoshi , Nakamura Ayami , Nakata Kazuhiko , Kawai Takahiro , Nakamura Hiroshi
Published: March 2009

Bone morphogenetic protein (BMP) is known as a protein that induces new bone in heterotopic sites. This study was conducted to assess the cell-biological effects of crude porcine BMP and 3 pulp-capping materials by implantation and cell culture methods. The following results were obtained: a new bone site of approx 5mm in diameter were induced in the hind limbs, which confirmed the osteoinductive activity of the crude BMP. The pulp-capping materials hardly influenced the calcification of rat dental pulp (RDP) cells. Our data also suggest that the effect of
the crude BMP on the proliferation and calcification depended on its quantity. The finding of a large increase in the ALPase activity and the formation of mineralized nodules caused by the crude BMP , suggests that the crude BMP enhanced the calcification by RDP cells. Consequently, it is quite possible that crude porcine BMP could be used as a pulp-capping material.
Fracture Properties and Characteristics of Sisal Textile Reinforced Epoxy Composites
Authors: Li Yan , Mai Yiu Wing , Ye Lin
Published: March 2009

In this paper, double cantilever beam (DCB) and end notch flexural (ENF) tests were performed to study mode I and mode II interlaminar fracture toughness of sisal textile reinforced epoxy composites. Two kinds of fiber surface treatment methods were used to improve the interfacial bonding properties between sisal fiber and the epoxy resin. Effect of fiber surface treatments on mode I and mode II fracture toughness was analyzed with the aid of microobservation and single fiber pull-out test. It was concluded that proper fiber surface treatment could improve the fracture properties of this kind of Eco-composite.
A Note on the Characteristic Length/Time of Dual-Porosity Models for Geologically Fractured Media
Authors: Lu Meng , Connell Luke D.
Published: March 2009

This short note presents a discussion on the characteristic length that appears in dualporosity models for fractured geological media, via which the empirical characteristic diffusion time is defined. The physical meaning of it is further interpreted here from a more rigorous mathematical point of view, relating the so-called characteristic length or, equivalently, the characteristic time, to a statistically averaged quantity over a local representative volume element that contains numerous matrix blocks. Each of these matrix blocks will be of distinct characteristic
lengths or times unless the geometrical shapes and sizes (in an effectively volume-equivalent way) of them are identical. Theoretically, those characteristic lengths could be statistically determined through measurement of their typical distributions. Thus, the discussion presented in this article may permit one to have greater insight into the nature of these two parameters, and may also allow a laboratory approach to measure them to be developed.
Size Effect of Shear Fracture Energy of Concrete in Uniaxial Compression Based on Gradient-Dependent Plasticity
Authors: Wang X.B.
Published: March 2009

Gradient-dependent plasticity where a characteristic length is involved into yield function is adopted to calculate the thickness of shear band (SB) and the distribution of plastic shear strain in SB. The characteristic length reflecting the heterogeneous extent of texture only controls SB’s thickness. The local plastic shear strain in SB is highly non-uniform. The total fracture energy is the sum of pre-peak and post-peak fracture energies. The pre-peak part is described by the nonlinear Scott model and depends on the height of specimen. The post-peak part is calculated through the derived post-peak relative stress-plastic deformation curve. If the inclination angle of SB is not influenced by the height, then the slope of post-peak relative stress-plastic deformation curve and the post-peak fracture energy are independent of the height. The total fracture energy is linearly size-dependent as the pre-peak fracture energy is linearly related to the height. The slope of postpeak relative stress-plastic deformation and the total fracture energy are verified through previous experiments for normal concrete in uniaxial ompression.
Analysis of Non-Linear Relationship between Specific Work of Fracture and Ligament of Polymeric Materials Using Modified EWF Model
Authors: Duan Kai , Hu Xiao Zhi
Published: March 2009

This paper explores the ligament-dependent behaviour of specific work of fracture of polymeric materials using a recently-developed modified EWF model. It is demonstrated that the non-linear relationship between specific work of fracture (wf) and ligament length (l) is a result of specimen boundary influence on the evolution of plastic zone. A transition ligament (l*) is defined, below which, the height of under-developed plastic zone is equal to the ligament length, and as a result, a linear wf-l relation will be observed. The plastic zone will saturate at the transition ligament, and its height will no longer increase when l > l*. This will result in a non-linear wf-l relation. Experimental wf-l data available in the literature are analysed using the modified EWF model and very good agreements are achieved.
A Simple Method for Evaluating Flaw Distributions Responsible for Size Effects in the Strength of Small-Scale Silicon Specimens
Authors: Duan Kai , Hu Xiao Zhi
Published: March 2009

A simple means of deconvoluting the size distributions of fracture-controlling flaws from Weibull strength plots for small-scale specimens is proposed. The method makes use a power-law distribution function, empirical in form but self-consistent with a conventional two-parameter Weibull probability distribution. Literature data for single-crystal silicon beam specimens covering a range of widths from mm to nm are analyzed according to this procedure. The analysis indicates a reduction in scatter in addition to increase in strength with diminishing specimen size, and quantifies a systematic tightening in flaw distribution associated with refinement in fabrication
method.
Mechanical Behavior of a Hybrid Reinforced Magnesium Composite Fabricated by Pressure Infiltration Method
Authors: Qin Ji Ning , Zhang Di , Zhang Guo Ding , Jin Quan
Published: March 2009

A hybrid reinforced composite based on magnesium alloy AZ60A reinforced with B4C particulates and SiC wisker, with volume percentage of 12% of each reinforcement respectively, was fabricated using pressured infiltration processing technique followed by hot extrusion. The microstructure of the composite and the fracture surface of tensile sample were investigated by optical microscopy and scanning electron microscopy (SEM). The results show a nearly uniform distribution of the reinforcements throughout the as-extruded magnesium matrix, and the SiC wiskers were observed with its longitudinal distributing along with the extrusion direction. Tensile experiment after extrusion revealed that the hybrid reinforcements significantly increase the elastic modulus and ultimate tensile strength of the composite material. The elastic modulus and the ultimate tensile were reached to 80.2GPa and 420 MPa, which were 100% and 34% higher than that of the matrix material. Moreover, numerical models (FEM) by an axisymmetric unit cell method were used to investigate the evolution of voids volume fraction in metal matrix during tensile process. The results show that the cracking is prone to form and grow near wisker than particulates.
Mg-Y-Cu Bulk Nanocrystalline Matrix Composites Containing WC Particles
Authors: Lee Pee Yew , Lo C. , Jang Jason S.C. , Huang J.C.
Published: March 2009

The preparation of Mg49Y15Cu36 metallic glass composite powders was accomplished by mechanical alloying of pure Mg, Y, Cu, and WC powder mixture after 10 h milling. In the ball-milled composites, initial WC particles were homogeneously dispersed in the Mg-based alloy glassy matrix. The metallic glass composites powders were found to exhibit a large supercooled liquid region before crystallization. Bulk metallic glass composites were formed by vacuum hot pressing the as-milled WC/ Mg49Y15Cu36 metallic glass composite powders at 473 K in the pressure range of 0.72-1.20 GPa. BMG composite with submicron WC particles homogeneously embedded in a highly dense nanocrystalline/amorphous matrix was successfully prepared under pressure of 1.20 GPa. It was found that the applied pressure during consolidation could enhance the thermal stability and promotes nanocrystallization of WC/ Mg49Y15Cu36 BMG composites.