bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulsating Fatigue Properties of Stainless Steels
Authors: Nishida Shinichi , Hattori Nobusuke , Shimizu Takamitsu , Iswanto Priyo Tri
Published: March 2009

The object in this study is to investigate the pulsating fatigue properties of ferritic and martenstic stainless steels using replica method. The main results obtained in this test are as follows; two kinds of ferrritic stainless steels show the same fatigue strength, even if there is difference in micro-structures due to charge of heat treatment condition. In addition, the fatigue limit of martenstic stainless steel shows higher than that of ferritic one by 230%. It is considered that the static mechanical properties relate to the mean value of micro-structures and the fatigue strength relates to the weakest portion of structures. In addition, the ratio between fatigue limit and hardness number becomes considerably smaller than that of conventional structural steels.
Thermal Fatigue Life Prediction of ACF Bonding Flip Chip Packaging
Authors: Nam Hyun Wook
Published: March 2009

The use of flip-chip technology has many advantages over other approaches for
high-density electronic packaging. ACF (anisotropic conductive film) is one of the major flip-chip technologies, which has short chip-to-chip interconnection length, high productivity, and miniaturization of package. In this study, thermal fatigue life of ACF bonding flip-chip package has been predicted. Elastic and thermal properties of ACF were measured by using DMA and TMA. Temperature dependent nonlinear bi-thermal analysis was conducted and the result was compared with Moire interferometer result to verify FEM results. Calculated displacement field was well
matched with experimental result. Thermal fatigue analysis was also conducted. The maximum shear strain occurs at the outmost located bump. Shear stress-strain curve was obtained to calculate fatigue life. Fatigue model for electronic adhesives was used to predict thermal fatigue life of ACF bonding flip-chip packaging. Approximately, 700 cycles have been expected under current conditions (JEDEC
standard No. 22-A104)
Strength of Nanostructured Materials Using a Phase Mixture Model
Authors: Kim Hyoung Seop , Lee Jai Sung
Published: March 2009

A phase mixture model (PMM) was considered in which materials are treated as a mixture of grain interior phase, grain boundary phase and pores (if the material is porous) for the elasticity and plasticity of nanostructured materials (NSMs). In order to investigate the effects of grain size and porosity on the elastic modulus, a self-consistent method in conjunction with PMM was employed. The calculated results are compared with the experimental measurements in the literature. The elastic modulus of NSMs decreases with a decrease of the grain size and the decrement is relatively large at grain sizes below about 10 nm. The effect of porosity, however, is substantially greater than the grain size effect. For the plasticity of NSMs, grain size effects were introduced both via the dislocation glide mechanism and through the diffusion mechanisms providing mass transfer via grain boundaries. A good agreement between the calculated deformation behavior and experiment was found. The quality of the above predictions with regard to strength, strain hardening, strain sensitivity and ductility behavior testify the adequacy of the model. It is concluded that the model can be used as a convenient tool for simulating the deformation behavior of NSMs.
Mechanical Alloying of Al2O3-Co Powders Mixture
Authors: Yeo W.S. , Yaacob Iskandar Idris
Published: March 2009

Nanocomposite Al2O3-Co was prepared by high-energy ball milling technique.
Nanoscaled alumina particles (γ-Al2O3) of 5wt% with nominal size 39 nm were dispersed in cobalt matrix. The phase transformation of the element occurs in the powders mixture during the process was monitored by X-ray diffractometry (XRD). The results showed that cobalt exhibits phase transformation when subjected to ball milling. The phase formation of cobalt was found to depend on the milling intensity. As the milling time increased, the amount of the hexagonal close-packed (hcp) phase decreased.
Scattering of a Small Angle Incident Acoustic Wave from a Submerged Piezoelectric Cylinder
Authors: Liu Hua Rui , Lee Jung Ju
Published: March 2009

This paper is concerned with developing a mathematical model to describe the scattering of a plane wave obliquely incident on a piezoelectric hexagonal 6mm cylinder in a fluid. The mode is based on the normal-mode expansion method. Far-field form functions are obtained. The sensitivities of Rayleigh, Whispering Gallery, and guided wave resonances to perturbations in elastic and piezoelectric constants are discussed. The resonance scattering theory can be used for characterizing the sample in both transverse and axial directions.
Dynamics of a Vibrating Micro Three-Axis Ring Gyroscope
Authors: Kim Chang Boo , Cho Chong Du , Beom Hyeon Gyu
Published: March 2009

This paper presents electro-mechanical characteristics of a micro-machined vibrating silicon ring gyroscope which can measure angular velocity components about three orthogonal axes. The ring gyroscope has a ring connected to the gyroscope main body by support ligaments that are arranged with cyclic symmetry. The natural modes of its vibration can be distinguished into the in-plane motion and the out-of-motion that are coupled by the gyro-effect due to the rotation of the gyroscope main body. The motions of the ring are electro-statically driven, sensed and balanced by electrodes. The equations of motion are formulated with considering the electrostatic effects of electrodes. The measuring method of angular velocities of the gyroscope main body by force-torebalance is proposed. The dynamic characteristics of the ring gyroscope are discussed.
Computational Simulation of a Total Knee Prosthesis Mechanical Behaviour
Authors: Bratianu Constantin , Gruionu Lucian
Published: March 2009

The design of knee prostheses can be improved by computer aided design and structural analysis based on the finite element simulation. Our assumption is that by knowing the stress patterns between the knee prosthesis components and between this implant and its surroundings, we can better evaluate the wear performances and improve its design. The geometry of mobile bearing knee prosthesis with a polyethylene insert was used to predict peak and average contact pressures in
several explicit dynamics finite elements analyses. The contact pressure, shear stress distribution and shear movements at the interface implant-cement and bone-cement are important for prostheses life and were computed. Rigid body dynamics analysis was used to predict body positions and orientations. Numerical modeling and simulations are used to predict contact pressures between three-dimensional surfaces. Our computational results showed a positive matching with experimental data from literature. This modeling approach is sufficiently fast and accurate to be
used in design sensitivity and optimization studies of knee implant mechanics.
Fracture Toughness of Nanoscale Hydroxyapatite Coatings on Titanium Substrates
Authors: Roest R. , Heness Greg , Latella Bruno A. , Ben-Nissan Besim
Published: March 2009

In the biomedical field, the surface modification of titanium aims to inhibit wear, reduce corrosion and ion release, and promote biocompatibility. Sol-gel-derived ceramic nanoscale coatings show promise due to their relative ease of production, ability to form a physically and chemically uniform coating over complex geometric shapes, and their potential to deliver exceptional mechanical properties due to their nanocrystalline structure. In this study hydroxyapatite coatings on titanium were investigated for their fracture toughness.
Mechanical Properties of Al-3%Ti Thin Film for Reliability Analysis of RF MEMS Switch
Authors: Park Jun Hyub , Kim Yun Jae , Choa Sung Hoon
Published: March 2009

This paper presents a novel experimental method to investigate the strength of material, Al-3%Ti, which is commonly used in RF(radio frequency) microelectromechanical systems(MEMS) switch. The experimental method involves the development of a new tensile loading system. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position
measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. A voice coil of audio speaker is used as the actuator of the loading system. And new specimen was designed and fabricated to easily manipulate, align and grip a thin-film for a tensile and fatigue test. The material used in this study was Al-3%Ti thin film, which was used in RF
switch. The thickness and width of the thin film of specimen are 1.1µm and 480µm, respectively. The holes at center of grip end are able to make alignment and gripping easy. The bridges are to remove the side supports easily and extract specimen from wafer without sawing. Tensile tests were performed on 5 specimens. The ultimate strength of Al-3%Ti was 144MPa.
Analysis of Residual Stress in Thin Wall Injection Molding
Authors: Lee H.K. , Huang J.C. , Yang G.E. , Kim Hong Gun
Published: March 2009

A relationship of residual stress distribution and surface molding states on polymeric
materials is presented in thin-walled injection molding. The residual stress is computed by computational numerical analysis, observed with stress viewer and birefringence. The residual stress on polymeric parts can allude the surface quality as well as flow paths. The residual stress distribution on polymeric parts is related with thickness, gate layout, and polymer types. Molecular orientation on
polymeric parts is also important in thin wall injection molding. The residual stress and molecular orientation are related to the surface molding states intimately. Analysis of the residual stress is validated through photo-elastic method and surface molding states..
Flexural Behavior of Concrete Beam Reinforced with Steel and FRP Re-Bars
Authors: Nam Jeong Hun , Lee Seung Sik , Yoon Soon Jong , Jang Won Sup , Cho S.K.
Published: March 2009

FRP composite materials are widely applicable in the construction industries as a
load-bearing structural element or a reinforcing and/or repairing materials for the concrete. In this paper, we presented the flexural behavior of steel reinforced concrete beams reinforced with FRP re-bars manufactured by different fibers but the same vinylester resin. Experimental investigation pertaining to the load-deflection and load-strain characteristics of steel reinforced concrete beams
reinforced with FRP re-bars with garnet coated surface is presented and the theoretical prediction is also conducted. In the investigation, the effects of FRP re-bar reinforcement in addition to the steel reinforcement are estimated. The experimental results are compared with theoretical predictions. Good agreements are observed.
Study on the Structure Model and Controlling Method of Subsidence in Flat Seam and Deep Mining
Authors: Wang Chong Ge , Chen Wei Zhong , Pan Liyou
Published: March 2009

The stratum movement and surface subsidence is considered as a whole system in the research work. The key of the surface subsidence control lies first in having thorough knowledge of the dynamic changeable of the overlaying strata movement as the face advances so as to establish the corresponding structure mechanics subsidence model in flat seam and deep mining. The common characteristic of stratum movement and the development procedure of crack arch are described in this paper. The structure constituents of subsidence and their influencing factors are also analyzed. Meanwhile, the surface subsidence is determined by the compressing of coal wall and the bending of the overlying strata. Based on the ground observation by the global positioning system, the boundary angle and the motion angle are determined. Furthermore, according to the research law, one can predict and control the surface subsidence damages for the special geologic conditions.
An Experimental Study on Low Cycle Fatigue of Inconel 617 Super Alloy
Authors: Kim Jae Hoon , Kim Duck Hoi , Lee Young Shin , Choi Young Jin , Kim Hyun Soo , Park Won Shik
Published: March 2009

Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.
Damage Detection of a Circular Cylindrical Shell with Frequency Sensitivities
Authors: Chen Jianyun , Wang Zhi Hua , Cheng Zai Bin , Ma Hong Wei
Published: March 2009

Damage detection using changes in global dynamic characteristics has been a hot research topic in recent years. In the present paper, based on natural frequencies and mode shapes, a numerical tudy locating and assessing damage in a circular cylindrical shell is presented. The axial position of the damage can be easily obtained by comparing the theoretical and measured frequency changes due to damage. Additional information of mode shapes is introduced to locate the exact damage position. And the damage extent can be estimated by the first order approximation method. The feasibility and practicality of the damage detection scheme are evaluated for several damage scenarios by locating and sizing damage in free-clamped shells. The results illustrate that the proposed detection scheme can confidently locate the single or multiple positions of damage. It is also observed that damage extent can be estimated with a relatively small error.
Determination of Pressure-Temperature Limit Curves Using Deterministic and Probabilistic Approaches
Authors: Jung Sung Gyu , Park In Gyu , Lee Chang Soon , Kim Hyun Su , Jin Tae Eun
Published: March 2009

Reactor pressure vessel (RPV) is the most critical component in nuclear power plant. RPV is subjected to radiation embrittlement, which is characterized as neutron fluence-dependent reduction in fracture toughness of the material. Therefore, risk for potential failure of RPV increases as operating time and fluence level increase. To prevent the potential failure, it is requested for RPV to operate in accordance with pressure-temperature (P-T) limit curve during operation. However, it has been reported that P-T limit curve which is typically developed in accordance with the procedure in ASME code is too conservative. Therefore, in order to investigate the conservatism of current P-T limit curve and develop more realistic one, probabilistic approach based on the risk was utilized in this paper. The resulting P-T limit curve is very higher than that from deterministic approach, and can be used as alternative operation limit of the RPV, because probabilistic P-T limit curve seems to have enough safety margin for potential failure of RPV.
Stress Analysis of the Automobile's Coil Spring Including Residual Stresses by Shot Peening
Authors: Bae Dong Ho , Lee Gyu Young , Jung Won Seok
Published: March 2009

Durability assessment for the suspension system of the vehicle is very important. In order to secure reliability on the results of durability assessment and fatigue design criterion, accurate stresses for the interesting component must be basically calculated. In this paper, numerical stress analyses for the automobile’s coil spring were performed. Residual stresses by shot peening were also analyzed. The effects of the stress analysis results on fatigue strength of the coil spring were discussed. From the results, fatigue durability of the shot peened coil spring could be considerably improved by the effects of compressive residual stress. However, being attacked by corrosive environments, it could decrease by corrosion fatigue degradation.
Parallel Computing for Wave Propagation Analysis Based on Cellular Automaton
Authors: Wada Yoshitaka , Matsumoto Takayoshi , Kikuchi Masanori
Published: March 2009

We have proposed a cell based parallel computing system using a cellular automaton
model. The proposed system is designed by object-oriented technique to realize extensibility for parallel cellular automaton model. Because the system needs only information of model as cells which are represented by pixel and voxel mesh, model generation is very easy from any data formats. We implement several applications, which are 1-D life game, 2-D life game, 2-D diffusion, 2-D parallel diffusion, 2-D wave propagation, 3-D wave propagation and 3-D parallel wave propagation on the system. Status of cells is updated by adjacent status of cells. In other worth, behavior of system is completely specified in terms of a local relation. Cells can hold many properties to represent its status. Cellular automata system can calculate physical phenomena and discrete problem like a life game simultaneously. We present some results of a physical analysis and discrete analysis, and discuss effectiveness and parallel efficiency of proposed system.
Transition Method of Geometrically Similar Element for Dynamic V-Notch Problem
Authors: Li You Tang , Yan Chang Feng , Kang Yong Ping
Published: March 2009

A semi-analytical method is proposed to determine the dynamic stress intensity factor of two-dimensional V-notch problems. A group of geometrically similar elements is automatically generated layer by layer around the point of singularity. The large number of degrees of freedom around the V-notch tip are transformed to a small set of generalized coordinates by means of the series expansion formulas of the displacement field. By taking advantage of the same stiffness and similar mass of 2D similarly shaped elements, a single transformation of the stiffness and mass for
the first two layers of mesh is enough for all. As an example, the three points bending specimen with V-notch is analyzed.
Construction of Space-Time High Resolution Second Order Accurate Three Dimensional MP Difference Schemes
Authors: Wu Kai-Teng , Ning Jian Guo
Published: March 2009

In this paper, a new Riemann-solver-free class of difference schemes are constructed to scalar nonlinear hyperbolic conservation laws in the three dimension (3D). We proved that these schemes had second order accuracy in space and time, and satisfied maximum principles (marked as MPs) under an appropriate CFL condition. This results in a second-order accuracy, MP schemes a natural extension of the one (two)-dimensional second-order. In addition, these schemes can still be extended to the vector system of conservation law. We yet prove that these schemes satisfied the scalar and vector maximum principle, and in the more general context of systems.
Numerical Simulation of Impact Crush/Buckling of Circular Tube Using SPH Method
Authors: Kikuchi Masanori , Miyamoto Masayuki
Published: March 2009

SPH (Smoothed Particle Hydrodynamics) method is applied to impact crush/buckling problem of circular tube. It has been known that there are several kinds of buckling modes by axial impact load. First, elastic analyses of the crush/buckling are conducted, and three types of typical crush/buckling shape are obtained. Following the elastic analyses, elastic-plastic analyses were performed to improve the accuracy of the simulation. The shape of the buckling and the energy absorbed by circular tube are discussed.
Evaluation of the Degradation Characteristics of CF-8A Cast Stainless Steel Using Indentation Techniques and EDS
Authors: Baek Seung , Koo Jae Mean , Seok Chang Sung
Published: March 2009

Cast austenitic stainless steel piping pump, valve casings and elbows are susceptible to reductions in toughness and ductility because of long term exposure at the operating temperatures in the LWR (light water reactor). In this study, the three classes of thermally aged CF-8A cast austenitic stainless steel specimens were prepared using an artificially accelerated aging method for 0, 2,679 and 3,572 hours at 400oC. An indentation technique was applied to evaluate of the thermal aging of CF-8A cast austenitic stainless steel. We have performed indentation tests (automated ball indentation and nano-indentation) and EDS (energy dispersive spectroscopy) in order to characterize the micro-structural changes of the phase with aging. The fracture toughness of aged CF-8A cast stainless steel was determined by standard fracture toughness tests and automated ball indentation techniques.
A Study on Boronizing of Duplex Stainless Steel
Authors: Hasan Rafidah , Jauhari Iswadi , Yunus S.M. , Ramdan Raden Dadan , Masdek Nik Rozlin Nik
Published: March 2009

Boronizing is a method to increase the surface hardness of engineering components [1]. This is beneficial especially when the components are always in surface contact with other materials. In this study, boronizing treatment was successfully done on duplex stainless steel (DSS). Two types of DSS with different microstructure were boronized – the as-received DSS and the fine grain DSS. The morphology of boride layer formed on boronized DSS is compact and smooth. The boride layer thickness for both DSS ranged from 9 to 32 +m. Depending on boronizing time and temperature, the hardness of boronized fine grain DSS is between 1014 HV to 2601 HV. The values are higher than that of the as-received DSS which is between 797 HV to 2311 HV. The result shows that there is a different in hardness of boride layer for two different grain sizes of DSS although the layer thickness formed is about the same in depth.
A Phenomenological Constitutive Model Constructed for PC/ABS Blends
Authors: Nizar Machmud M. , Omiya Masaki , Inoue Hirotsugu , Kishimoto Kikuo
Published: March 2009

Based on previous available constitutive models, a phenomenological constitutive model has been constructed and is proposed to describe the strain, strain rate and temperature dependentdeformation behavior of PC/ABS blends. In this paper, four quasi-static uniaxial tension tests of a specimen tested at different strain rates and temperatures were used to identify the constitutive model constants. By using the proposed constitutive model, predicting the stress-strain behavior of the PC/ABS blend tested at certain strain rate and different temperatures compares well to the
behavior exhibited from the tests. From comparison between the DSGZ and the proposed models, proposed model shows a better prediction. Evaluation of the proposed constitutive model was also presented and it has revealed that the proposed model might have a potential to be used for predicting a wide range of temperatures and high strain rates behavior of PC/ABS blends.
Porous Bioceramics (Open Cell Foams) Expanded in Vacuum
Authors: Uzumaki E.T. , Lambert C.S.
Published: March 2009

In this study, porous bioceramics (titanium foam with diamond-like carbon coatings,
glass foam and zirconium oxide foam) were produced using expansion in vacuum. The porosity, the pore size and pore morphology can be adjusted in agreement with the application. The different 3D structures were obtained by varying the parameters of the process. The microstructure and morphology of the porous materials were observed by scanning electron microscopy (SEM) and
optical microscopy. The foam exhibit an open-cell structure with interconnected macropores, which provide the potential for tissue ingrowths and the transport of the body fluids.
Evaluation of Biocompatibility for Porous Bioactive Glass Scaffolds
Authors: Salgado C.L. , Turchetti-Maia R.M.M. , Pereira Marivalda , Salas C.E. , Francischi J.N. , Lopes M.T.P.
Published: March 2009

The objective of this work is to evaluate the cytotoxicity, acute and chronic inflammatory response and mutagenicity of a high porosity bioactive glass (BG60S), produced by sol-gel method. The BG60S analyzed by direct contact and elution tests showed cytotoxic levels compatible with international standards (ISO 10,993-5). The BG60S extract reduced by ≈50% the cellular viability of L929, CHO and CPis cells measured by the MTT assay. The diluted extract (1:3) restored the cellular viability. We did not find edema induction in the rat paw test, nor cell migration to peritoneum, as measured by the inflammatory acute response. A BG60S implant did not induce chronic inflammation measured by hemoglobin levels (blood vessels formation), as well as the presence of macrophages and neutrophils (NAG and MPO activities, respectively). The BG60S extract was unable to induce colony reversion of Salmonella thyphimurium (with or without S9), thus precluding its mutagenic activity.
Osteoblast Proliferation and Morphology Analysis on Laser Modified Hydroxyapatite Surfaces: Preliminary Results
Authors: Teixeira S. , Queiroz A.C. , Monteiro F.J. , Ferraz M.P. , Vilar Rui , Eugénio S.
Published: March 2009

Biocompatibility has long been associated with surface microtopography, microtexture and microchemistry. The surface topography ultimately affects the nature and the strength of the interactions that occur at biomaterial-biological environment (cell adhesion, mobility, spreading and proliferation). Thus, it is necessary to produce and work with controlled microtopographical surfaces that present reproducible microdomains of a dimension similar to that of the biological elements of interest (for instance, cells). [1] There are a number of substrates that already have been studied (such as silicone, polystyrene, poly-L-lactic acid and titanium coated polystyrene) in terms of surface topography. [2] However, few studies are related to hydroxyapatite substrates. As it is well established, hydroxyapatite is a well known ceramic that is extremely used in medical applications, namely implants and coatings. In this work, the surface topography of dense hydroxyapatite substrates was altered by using KFr excimer laser. Excimer lasers produce high-intensity, pulsed ultraviolet radiation and are especially well suited for materials processing due to their large beam cross-section area, which permits using mask projection technologies to process relatively large areas in a single step.[3]
Preparation of Porous Hydroxyapatite / Tricalcium Phosphate Composite Block Using a HHP Method
Authors: Song Hee , Kim Soo Ryong , Hwang Jong Hee , Kim Y.
Published: March 2009

Porous hydroxyapatite/tricalcium phosphate composite block has been prepared using a hydrothermal hot pressing (HHP) technique to achieve having a high mechanical strength and controlled biodegradability. The SEM result of the sample shows that the pore sizes are ranged from 100µm to 300µm. The observed X-ray powder diffraction pattern of the sample after sintered 1200oC is composed of hydroxyapatite and tricalciumphosphste.
The Preparation and Properties of Layered TCP/Y–TZP Composites with Ribbon-Like Microstructures
Authors: Kosmač Tomaž , Dakskobler Aleš
Published: March 2009

The repeated-deformation processing technique was used in the preparation of layered tricalcium phosphate (TCP)/yttria partially stabilized tetragonal zirconia (Y-TZP) composites with ribbon-like microstructures. The fabrication technique involved repeated plastic deformation of layered green tapes, which are stacked together to form starting bi-material laminates, burn-out of the organic vehicle, and sintering at 1300°C. At this rather low sintering temperature, which was chosen to prevent the extensive diffusion of the calcium into the Y-TZP, the zirconia layers could not be fully densified. In spite of the relatively low fractional density (about 75% TD) of these layers, flexural strength values exceeding 100 MPa were achieved with these composites, 150% higher than the matrix material. During autoclaving in water at 200oC for 24 hours no t-m transformation of the zirconia phase took place, indicating full stability of the porous zirconia layers in these composites under the hydrothermal conditions used in this study.
Wollastonite-Poly(Ethylmethacrylate-Co-Vinylpyrrolydone) Nanostructured Materials: Mechanical Properties and Biocompatibility
Authors: Rodríguez-Lorenzo Luis M. , García-Carrodeguas R. , Rodríguez M.A. , De Aza S. , Jiménez J. , López-Bravo A. , Fernandez M. , San Román Julio
Published: March 2009

Synthetic pseudowollastonite (psW) and a nanostructured copolymer made of a biostable component, Poly(ethylmethacrylate) (PEMA) and a bioresorbable component, vinylpyrrolidone (VP) are used in this work for the preparation of a new family of bone substitutes that allow osseointegration and mechanical stability. Composites are prepared by bulk polymerization of the desired composition in 15 mm diameter cylindrical plastic moulds. Polymerization was induced
thermally at 50°C using 1wt% azobis(isobutyronitrile) (AIBN) as free-radical initiator. The moulds were filled to a height of 100 mm and 1 mm height discs were cut with a diamond saw. Specimens with a ceramic/polymer ratio 58/42, 33/67,17/83 and 0/100 were obtained. Compression stress in the range 39-59 MPa and elastic modulus between 2.64 and 4.14 GPa are obtained where the
greater values correspond to the specimens prepared with a 60% ceramic load. Degradation in SBF produces a porous nanostructure in the polymeric component indicating microdomains of different solubility and the formation of an apatite-like layer on the surface of the wollastonite component.
All the compositions assayed present a biocompatibility at least of the level or even superior than the Thermanox® control used.
Bioactive Calcium Phosphate Material for Dental Endodontic Treatment. Root Apical Deposition.
Authors: Bosco Julia , Enkel Bénedicte , Armengol Valerie , Daculsi G. , Jean Alain , Weiss Pierre
Published: March 2009

An injectable bone substitute (IBS) made of a suspension of Calcium phosphate
ceramic was used to filled dental root canal after removing of canal pulp. The aim of this study was to verify the ability of calcium phosphate ceramic suspension to fill the apical zone of teeth ex vivo (n=40) and in vivo in a sheep model (n=8). The results showed that injection is possible with a good level of BCP granules at the end of the root dental canal with extracted tooth. In vivo, the presence of blood pressure due to the pulpectomy is a negative parameter to allow a good filling. The scanning electron microscopy revealed mineral formation at the apex level
with mineral tissue conduction between the BCP granules but only one tooth showed a good apical filling with a good sealing. The sealing of the apex seems to depend of the amount of BCP granules. Other experiments with other animal models closer to a Human model have to be performed before human trials.
Evaluation of Transformation Zone Around Propagating Cracks in Zirconia Biomaterials Using Raman Microprobe Spectroscopy
Authors: Shimozono Takayoshi , Ikeda Junji , Pezzotti Giuseppe
Published: March 2009

Structural reliability, biocompatibility and bioinertness are fundamental prerequisites for bioceramics used in artificial hip and knee joints. Among structural properties, superior fracture toughness is necessary for guaranteeing high reliability during implantation lifetime. Bioinert ceramics employed in artificial joints are mainly limited to alumina and zirconia materials. In this paper, the critical crack-tip stress intensity factor, KI0, and the tetragonal-to-monoclinic phase-transformation behavior of a 3 mol % Y2O3-doped tetragonal ZrO2 polycrystals (3Y-TZP)
were studied as a function of grain size. 3Y-TZP’s with four different grain sizes were prepared and the size and morphology of the monoclinic transformation zone generated around the tip of an indentation crack were analyzed by quantitative Raman microprobe spectroscopy. The stress intensity factor, KI0, was evaluated by the crack opening displacement (COD) method using a recently proposed equation for calculating the compliance of an indentation crack.
Phase Stability of Zirconia Toughened Alumina Composite for Artificial Joints
Authors: Ikeda Junji , Pezzotti Giuseppe , Nakanishi Takefumi
Published: March 2009

The phase stability under aqueous condition and changes in the wear region after the Pin-on-Flat wear testing were evaluated using Raman and fluorescence spectroscopy techniques and X-ray diffractometry for a newly
developed zirconia toughened alumina (JMM-ZTA). This study suggests that JMM-ZTA is a highly stable material under aqueous environment in the human body and has a high wear resistance in Pin-on-Flat wear tests. This results from a transformation toughening mechanism operative in JMM-ZTA. Therefore,
JMM-ZTA appears to have a possibility to improve the performance of monolithic alumina as a material for hip and knee joint prostheses.
Wear of Low Temperature Degradation-Free Zirconia/Alumina Composites in a Ceramic-Ceramic Contact Pair
Authors: Lee Kwon Yong , Kim Hwan , Kim Dae Joon , Lee Myung Hyun , Seo Won Seon
Published: March 2009

The sliding wear behaviors of three different compositions of novel low temperature
degradation-free zirconia/alumina (LTD-free Z/A) composites were examined in a ceramicceramic contact pair. The wear tests were performed by using a pin-on-disk type wear tester in a linear reciprocal sliding motion with a line contact in both dry and bovine serum lubricated conditions at room temperature. From the results of dry sliding wear tests, Z/A#1 ((5.3Y,4.6Nb)-TZP/80 vol% Al2O3) showed the best wear resistance among three kinds of LTD-free Z/A composites. For the bovine serum lubricated sliding wear tests, wear was too little to be measured for all kinds of Z/A composites. These novel LTD-free Z/A composites having excellent wear resistance demonstrated a potential as the alternative materials for the ceramicceramic contact pairs of femoral head and acetabular liner in total hip replacement.
A Comparative Biomechanical Study of HA Block Kyphoplasty for Osteoporotic Vertebral Fractures
Authors: Okawa Akihiro , Matsuzaki Hiromi , Wakabayashi Ken , Nishimura Taichi , Oshima Masashi , Uei Hiroshi
Published: March 2009

We innovated a new technique and hydroxyapatite material “HA Block” in order to
decrease complications such as pulmonary embolization and correct kyphosis due to osteoporosis. A cadaveric study of vertebroplasty was attempted to confirm accurate the efficacy for three materials in terms of restoration of vertebral height, strength and stiffness after packing HA Block as compared with Polymethylmethacrylate Cement (PMMA) and alpha-tri-calcium phosphate
cement (Biopex-R) in cadaveric study. By using thoracolumber spines derived from elderly human cadavers, two kinds of vertebral fracture models: Flat and Wedge were made on MTS 858 Mini. Restoration rate after packing each material was best for HA Block. The strength of HA Block was
somewhat lower than PMMA and Biopex-R. It is suggested that HA Block had moderate and optimal strength to reduce stress to adjuscent vertebra and was enable to correct kyphosis in osteoporotic spine.
Performance for Bone Ingrowth of Biphasic Calcium Phosphate Ceramic Versus Bovine Bone Substitute
Authors: Daculsi G. , Corre P. , Malard Oliver , LeGeros Racquel Z. , Goyenvalle Eric
Published: March 2009

Calcium phosphate bioceramics and bovine bone xenograft with or without sintering are more or less used in orthopaedics or in maxillofacial surgery. In this study we compare in a rat femoral epiphysis model after 3 weeks of implantation the bone in growth at the expense of granules of same size of micro macro porous biphasic calcium phosphate MBCP, sintered bovine bone and unsintered BioOss.
Study on Calcified Structure of Sialolith in Duct as a Key to Know How to Prevent Stone Formation
Authors: Toyoda Chie , Sakae Toshiro , Kato Masataka , Hasegawa Kazuhiro , Ono Makiko , Okada Hiroyuki , Yamamoto Hirotsugu , Akimoto Yoshiaki
Published: March 2009

Salivary calculus is an ectopic calcification of high frequency in oral region. Many previous reports on the composition and structure of salivary calculus only showed apatite crystal as the main constitution but were not sufficient to clarify the formation mechanism. In this study, structural properties of the salivary calculus were investigated by the high-reproducibility non-destructive method such as optical microscope, micro-CT, micro-FT-IR and micro-XRD. In some cases, SEM, BSI, and EDS analysis were also carried out. The results showed that the salivary calculi were grouped into three by structure, and grouped into three or four by chemical composition and crystal components. The difference in structure and composition should be reflected by the formation mechanism.
Therapeutic Effect of Selected Biomaterials (Mg/Zn/F-CaPs, Administered by Injection) on Bone Properties of Ovariectomized Rats
Authors: Otsuka Makoto , Oshinbe Ayako , Ito Atsuo , Otsuka Kuniko , Higuchi William I. , LeGeros Racquel Z.
Published: March 2009

The purpose of this study was to evaluate the efficacy of magnesium (Mg), zinc (Zn) and fluoride (F)-containing calcium phosphate compounds (Mg/Zn/F-CaP) in correcting the bone mineral deficiency noted in ovariectomized (OVX) rats. In order to evaluate therapeutic effect of selected Mg/Zn/F-BCP preparations (G2: 1.13%Mg/13.6%Zn/2.5%F, G3:7.76%Mg/1.89%Zn /3.01%F and G4:2.72%Mg/3.75%Zn/1.35%F), suspensions consisting of Mg/Zn/F-CaP
preparations and of Zn-TCP (G1: 6.17%Zn) powder were injected in the right thigs of OVX rats for 4 weeks. Injection of Zn-TCP powder suspension in G1 and G2 groups led to the recovery of plasma Zn levels in OVX rats. The area under the curve of plasma Zn for the G2, G1 and Normal (not ovariectomized) control group (GN) groups were significantly lower than those of the group G3, G4 and OVX /untreated control (GC) groups (p<0.05). The bone mineral density (BMD) of the right femur was significantly higher than that of the left in G1, G2, G3 and G4 groups on day 28. However, there was no significant difference in the BMD between the left and right femur in the GC and GN groups.
Biomimetic Apatite Formation on Different Polymeric Microspheres Modified with Calcium Silicate Solutions
Authors: Leonor Isabel B. , Balas Francisco , Masakazu Kawashita , Reis Rui L. , Kokubo Tadashi , Nakamura Takashi
Published: March 2009

Bioactive polymeric microspheres can be produced by pre-coating them with a calcium silicate solution and the subsequent soaking in a simulated body fluid (SBF). Such combination should allow for the development of bioactive microspheres for several applications in the medical field including tissue engineering. In this work, three types of polymeric microspheres with different sizes were used: (i) ethylene-vinyl alcohol co-polymer (20-30 'm), (ii) polyamide 12 (10-30 'm) and (iii) polyamide 12 (300 'm). These microspheres were soaked in a calcium silicate solution at 36.5°C for different periods of time under several conditions. Afterwards, they were dried in air at 100°C for 24 hrs. Then, the samples were soaked in SBF for 1, 3 and 7 days. Fourier transformed infrared spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that after the calcium silicate treatment and the subsequent soaking in SBF, the microspheres successfully formed a bonelike apatite layer on their surfaces in SBF within 7 days due to the formation of silanol (Si-OH) groups that are quite effective for apatite formation.
Effects of Serum Proteins in Apatite Layer Formed in Culture Medium on Initial Adhesion and Cell Proliferation
Authors: Kizuki Takashi , Saito Takao , Ohgaki Masataka , Yokogawa Yoshiyuki
Published: March 2009

In cell culture medium containing serum proteins, a layer with a great role in
ostelblast-like cell’s growth formed on a HAp ceramics by a coprecipitation with a deposition of a bone-like apatite and an adsorption of serum proteins. The adsorption of proteins is influential in the apatite deposition and the cell adhesion. A component of serum albumin is forming < 80% of total serum proteins, therefore we focused on the serum albumin. The serum albumin was removed from
fetal bovine serum by using an albumin removal kit, and then the albumin free cell culture medium was prepared. The bone-like apatite layer was quickly formed on the HAp ceramics in the albumin free medium, however the high cell adhesion property was not confirmed. As a result of investigation of an initial cell adhesion, the initial cell adhesion property of the bone-like apatite layer was not excellent even though the layer contained the serum proteins. Moreover, the layer without serum proteins showed a meager cell adhesion property in every time of the cultivation.
Therefore, it was revealed that the adsorption of the serum proteins only on the surface was not enough to the improvement of the cell growth. And a few days cultivation was required for an appearance of the remarkable effect on the cell growth on the layer formed by a coprecipitation reaction about the bone-like deposition apatite and the serum proteins adsorption.
In Vitro Bioactivity Characterization of K-Mica-Fluorapatite Based Glass Ceramics Containing Varying Amount of TiO2 Addition
Authors: Göller Gültekin , Akin Ipek , Eruslu Niyazi , Kayali E.S.
Published: March 2009

The purpose of this study is to investigate the crystallization behavior and in-vitro bioactivity character of glass ceramics having 3:7 weight ratio of flourapatite (Ca5(PO4)3F) to potassium mica (K2Mg3AlSi3O10F2) as a function of titania addition, and compare the morphology of hydroxycarbonateapatite (HCA) layer formation depending on titania addition on ceramic composition. It is observed from microstructural investigations that there is no morphology change occurred on precipitated HCA layer depending on nucleating agent in glass-ceramics. TF-XRD analysis indicates that after precipitation of initial particulates, crystallization proceeds and crystallization of precipitated HCA phase increases by increasing the time. It is observed that Ca, P ion variation in solution has two stage in terms of precipitation’ first stage represents formation of amorphous HCA and the second stage is related with crystallization. FTIR analysis strongly supports TF-XRD analysis as well.
Comparison of Apatite Formation on Polyamide Films Containing Carboxyl and Sulfonic Groups in a Solution Mimicking Body Fluid
Authors: Ohtsuki Chikara , Kawai Takahiro , Kamitakahara Masanobu , Tanihara Masao , Miyazaki Toshiki , Sakaguchi Yoshimitsu , Konagaya Shigeji
Published: March 2009

Apatite formation on polyamide films containing either carboxyl or sulfonic groups was
compared in 1.5SBF, whose ion concentrations are 1.5 times those of a simulated body fluid (SBF). The sulfonic groups induced the apatite nucleation earlier than the carboxyl groups. In contrast, the rate of crystal growth depended not on the kind of functional group, but on the degree of supersaturation of the surrounding solution. The more ready association of sulfonic groups with calcium ions may lead to earlier
apatite nucleation than that of carboxyl groups. Adhesive strength of the apatite layer to polyamide film containing sulfonic groups was significantly lower than that with carboxyl groups depending on the chemical interactions as well as on the mechanical properties of the polyamide film.
Dissolution Kinetics of Nanoparticulate Calcium Phosphates and Inorganic Bone Phase
Authors: Bertazzo S. , Bertran Celso A.
Published: March 2009

In this work, the dissolution of calcium phosphates was studied through the calcium ion concentration, determined during the dissolution process in SBF (Simulated Body Fluid) at pH 6.35, 7.00 and 7.40, at 37oC. The results allowed the determination of the number of adsorption sites (ns) on the surface of the phosphates. Regardless of previous knowledge of the Ca/P ratio and
crystallinity of the studied phosphates, the ns values provide the evidence that at the end of the dissolution process, the surfaces of the phosphates are similar.
Influence of Acidity in Wet-Chemical Synthesis on the Joint of Nano-Sized β-Tricalcium Phosphate Particles with Collagen Fibrils in Their Composites
Authors: Zou Chao , Weng Wen Jian , Deng Xu Liang , Cheng Kui , Wang Xin Zhi , Du Pi Yi , Shen Ge , Han Gao Rong
Published: March 2009

β-tricalcium phosphate (β-TCP)/collagen composites are in the limelight for their
biomedical applications. It is believed that joint status of β-TCP particles with collagen fibrils plays key roles in both osteoconductivity and biodegradability of composites. In this work, the influence of acidity during synthesis on the joint status between nano-sized β-TCP particles and collagen fibrils is investigated. The composites are characterized by X-ray diffractometer and Field Emission
Scanning Electron Microscope. The results show that the joint status of nano-sized β-TCP particles with collagen fibrils in the composites depends on the acidity in collagen suspensions. A desired joint status with obvious disassembled collagen fibril, good particle dispersion and strong boding between the particles and the fibrils could be obtained when acidity of the collagen suspension is pH 2.
Surface Analysis and Clinical Study of Connective Tissue Around Calcium Phosphate Coated Titanium Dental Implants in a Canine Model
Authors: Zhao Bao Hong , Feng Hai Lan , Sun Xiao Dan , Cui Fu Zhai , Lee In Seop
Published: March 2009

A part of the titanium dental implant surface, which will meet connective tissue after being inserted in mandibular bone, was coated with calcium phosphate by ion beam assisted deposition (IBAD). Twenty-four implants of coated and uncoated group were randomly placed in mandibles after 3 months of premolars extraction in beagle dogs. All the implants were firmly anchored in the bone and had no clinical signs of peri-implant inflammation after 3-month insertion. The probing depth in calcium phosphate coated group is 1.9±0.2 mm, less than in control group (2.1±0.2 mm)
(p<0.05). Most of the probing sites tended to bleed upon probing in two groups. It might indicate that the calcium phosphate coating has the potential to promote soft tissue integration.
Tissue Response in the Femur of Rats After Implantation of Diamond-Like Carbon Coatings on Ti-13Nb-13Zr Produced by Plasma Immersion
Authors: Uzumaki E.T. , Lambert C.S. , Batista N.A. , Belangero W.D. , Zavaglia Cecília A.C.
Published: March 2009

Diamond-like carbon (DLC) coatings were deposited on titanium alloy (Ti-13Nb-13Zr) by plasma immersion process. DLC-coated Ti alloy and uncoated Ti were investigated in an animal model using the femoral condyles of rats for intervals of 4 and 12 weeks postoperatively. The interface between the implants and bones of the femoral condyles were analysed using scanning electron microscopy (SEM) by backscattering. The results showed that the DLC coatings were well tolerated in both periods.
Development of Novel Bioactive PMMA-Based Bone Cement and its In Vitro and In Vivo Evaluation
Authors: Cho S.B. , Takeuchi Akari , Kim Ill Yong , Kim Sang Bae , Ohtsuki Chikara , Kamitakahara Masanobu
Published: March 2009

In order to overcome the disadvantage of commercialized PMMA bone cement, we have developed novel PMMA-based bone cement(7P3S) reinforced by 30 wt.% of bioactive CaO-SiO2 gel powders to induce the bioactivity as well as to increase mechanical property for the PMMA bone cement. The novel 7P3S bone cement hardened after mixing for about 7 minutes. For in vitro evaluation, apatite forming ability of it was investigated using SBF. When the novel 7P3S bone
cement was soaked into SBF, it formed apatite on its surfaces within 1 week Furthermore; there is no decrease in its compressive strength within 9 weeks soaking in SBF. It is though that hardly decrease in compressive strength of 7P3S bone cement in SBF is due to the relative small amount of gel powder or its spherical shape and monosize. In vivo evaluation of the novel 7P3S bone cement
was carried out using rabbit. After implantion into rabbit tibia for several periods, the interface between novel bone cement and natural bone was evaluated by CT images. According to the results, the novel bone cement directly contact to the natural bone without fibrous tissue after implantation for 4 weeks. This results indicates that the newly developed 7P3S bone cement can bond to the
living bone and also be effectively used as bioactive bone cement without decrease in mechanical property.