bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Modelling and Assessment of Excavation Damaged Zone around the Underground Excavations: A Case Study
Authors: Qiao Deng Pan , Zhang Zong Sheng , Wang Shu Hong , Zhang Ya Bin
Published: March 2009

This paper presents a study on the quantification of the degree of damage from the
microseismic event data, for assessment of excavation damaged zone of anisotropic rock in
Jinchuan mine and presents numerical simulation and prediction on the deformation and failure
of the rock masses surrounding laneway under rock mass properties and excavating conditions.
Following an introduction to the engineering geology and mechanical properties of the rock
mass in the Jinchuan mine areas, this paper reveals the features of the measured in situ stresses
and puts emphasis on an analysis of the mechanism of underground opening and damage
induced by the underground mining. Stress and AE redistribution induced by excavation of
underground engineering results in the unloading zone in parts of surrounding rock masses. A
micromechanics-based model has been proposed for brittle rock material undergoing
irreversible changes of their microscopic structures due to microcrack growth. A systematical
numerical modeling analysis method was completed. Based on numerical modelling, a series of
predicting curves for rock mass response and deformation are obtained, which provides the
basis of guiding the design and construction of anisotropic rock cave in Jinchuan mine. The use
of the in situ stress field results in enhanced modeling of the stress concentrations and potential
failures at the mines has also been reviewed. Knowledge of the prevailing rock stress field at the
mines is a critical component for such modeling which has led to improved rock mechanics
understanding and operations at Jinchuan mines.
Hybrid Electro-Active Papers of Cellulose and Carbon Nanotubes for Bio-Mimetic Actuators
Authors: Yun Sung Ryul , Zhao Li Jie , Wang Nian Gui , Kim Jae Hwan
Published: March 2009

Electro-Active Paper (EAPap) materials based on cellulose are attractive for many applications because of their low voltage operation, lightweight, dryness, low power consumption, bio-degradability. The construction of EAPap actuator has been achieved using the cellulose paper film coated with thin gold electrode layers. This actuator showed a reversible and reproducible bending movement. In order to improve both force and displacement of this, efforts are made to construct hybrid EAPap actuators using cellulose paper coated with carbon nanotubes (CNT). To coat the CNT, single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) are dispersed in polyaniline (PANI) matrix, and the solution is coated on the EAPap by using a spin coater. It is expected that the use of CNT can improve the force output by enhancing the stiffness of the hybrid EAPap actuator. Furthermore, the presence of the PANI may improve the actuation performance of the EAPap material. The performance of hybrid EAPap actuators is tested in an environmental chamber in terms of free displacement, blocked force and electrical power consumption. The performance of hybrid actuators is investigated for bio-mimetic applications.
Study on the Low Cycle Fatigue Damage of Nodular Cast Iron Based on Elastic Modulus
Authors: Liu Jin Hai , Hao Xiao Yan , Li Guo Lu , Zhao Xue Bo , Liu Gen Sheng
Published: March 2009

The influence of fatigue ratio on the low cycle fatigue damage of nodular cast iron was
investigated by measuring the elastic modulus. The results indicated that the elastic modulus of
nodular cast iron is a sensitive parameter to the fatigue damage at low cycle. The fatigue damage
variable of nodular cast iron increases with cycle ratio. At the beginning and end period of cycling,
the damage of nodular iron increases sharply, and in the range of 0.2- 0.8 cycle ratio, the fatigue
damage grows gradually.
Study on Bending Fatigue Life of 42CrMo Steel with M+F Dual-Phase Structure
Authors: He Bo Lin , Yu Ying Xia , Shao Er Yu
Published: March 2009

The effect of undissolved ferrite amount on bending fatigue properties and failure
mechanism were studied by using 42CrMo steel with subcritical quenching process The amount of
undissolved ferrite were 0%, 10% and 15%, respectively. The hardness of the specimen was treated
to medium hardness. The experimental results show that the existence of undissolved ferrite can not
only change the microstructure, but also increase the bending fatigue life. The bending fatigue life
elongates with increasing of amounts of undissolved ferrite. The grains can be fined by using
subcritical quenching process and the area of phase boundaries can also be greatly increased
because of undissolved spheroidal carbide. The martensite and carbide can also be changed using
subcritical quenching process. Stress relaxation due to the move of dislocations inside the ferrite
and the promotion of strength due to occurring of plastic deformation and enwinded dislocations are
main reasons of improving the bending fatigue life. The bending fatigue life elongates with the
increase of amounts of undissolved ferrite before the amount of undissolved ferrite reaches 10%.
Under the experiment conditions, when the amount of undissolved ferrite is 10%, the bending
fatigue life will be the longest.
FDM/FEM Hybrid Method with a Systematic Field Data Conversion Procedure for Thermal Stress Analysis in Casting Process
Authors: Choi Bong Hak , Kim Woo Jung , Cho Chong Du , Kwak Si Young , Choi Cheong Kil
Published: March 2009

Noticeably in casting and heat treatment process, computational methods are commonly engaged to predict process and mechanical characteristics such as solidification time, cooling speed, hardness and residual stress, in which analyzing thermo-mechanical coupled process necessitates such heat transfer, microstructure transformation, and stress. This paper proposes a FDM/FEM hybrid method for thermal stress analysis in casting process; taking advantage of each computational method, we use both FDM and FEM to analyze thermal stress. We use FDM to predict temperature distribution and microstructure and then transfer the result data to FEM to calculate thermal stress distribution. In this process, a systematic field data conversion procedure is developed for a successful data transfer. For the validation of this proposed method, numerical examples are presented and compared with antecedent experiment results. The interface data conversion program developed in this study can be used for any other program as well as FDM and FEM.
Force Transfer Mechanism in Embedded Steel Column Bases
Authors: Kim Young Ho , Lee Seung Sik , Jung Jae Ho , Yoon Soon Jong
Published: March 2009

This paper presents the results of an investigation on the force transfer mechanism in an embedded column base of a composite structure. In the experimental program, eighteen push-out specimens were tested. The factors influencing the mechanism of force transfer were the amount of confining reinforcement, compressive strength of concrete, and diameter of stud connectors. The results of experiment indicated that force transfer could be characterized into two stages, and the factors governing each stage were identified. The first stage was governed by the bond strength between the steel column base and the concrete. The second stage begun after chemical debonding and was governed by the shear strength of stud connectors as well as the frictional strength between the steel and the concrete. Based on the experimental results, the equations to estimate the bond strength, the friction strength, and the shear strength of stud connectors were proposed. The load carrying capacity of an embedded steel column base could be predicted by taking the sum of the shear strength of stud connectors and the friction strength. The predicted load carrying capacity was found to agree well with the experimental results over various range of concrete stress.
Evaluation of Load Carrying Capacity of the Perforated Shear Connector with Flange Heads
Authors: Kim Young Ho , Jung Jae Ho , Yoon Soon Jong , Jang Won Sup
Published: March 2009

In the construction of composite bridge structures, various types of shear connectors are usually used to provide an efficient load transfer and the composite action of two or more different materials. In the previous work conducted by authors, a new type of the shear connector was introduced, which is the perforated shear connector with flange heads (T-shaped perforated shear connector), and the structural behavior of the shear connector was discussed based on the results of push-out tests. For the practical design of new shear connector, it is necessary to develop the equation for the prediction of the load carrying capacity of the shear connector. In this study, the existing design equations for the Perfobond shear connector were briefly analyzed and the equation for the prediction of the shear capacity of T-shaped perforated shear connector was suggested empirically. By comparing the results obtained by the suggested equation, the existing equations for the Perfobond shear connector, and the experiment, the applicability and effectiveness of the suggested equation was estimated.
Modeling of Laser Dressing for Metal-Bond Diamond Grinding Wheel
Authors: Wang Xu Yue , Kang Ren Ke , Xu Wen Ji , Wang Lian Ji , Guo Dong Ming
Published: March 2009

Laser processing of super-abrasive grinding wheel is paying a role in a truing/dressing technique to complement mechanical methods recently. However, normal dressing/truing is difficult owing to the toughness of metal-bond materials and high hardness of diamond abrasive. Both geometric and mathematic models were developed to improve laser processing quality and predict various processing parameters, such as focal offset, and incident power, and power density to perform material removal during laser processing a metal-bond diamond grinding wheel. Various trends of the geometrical features of dressing zone in terms of the varying focal offsets were analyzed. Discussions were also given on dressing-zone geometry control. Experimental studies were carried out using different processing parameters to test the effects of laser poweres on dressing quality. Further grinding-force measurement determined the laser dressing parameters with respect to the wheel surface conditions. The normal force FN reduces up to 20%, while tangential force FT decreases to 7% too.The outcomes were shown well agreement with predicted results.
Experimental Research on Ultra-Smooth Surface Polishing Based on Two-Dimensional Vibration of Liquid
Authors: Guo Zhong Ning , Huang X.Z. , Huang Zhi Gang , Yu Z.Q. , Yue T.M. , Lee Wing Bun
Published: March 2009

Experiment research of polishing based on liquid two-dimension vibration is carried out by a vibrating device which is driven by ultrasonic source and can produce coupling vibrations of liquid. Sound pressures of some key points in water are tested by hydrophone and translated into sound intensity to evaluate the effect of input voltage of transducer. It is analyzed which vibration state of fluid field and the way that workpiece is clamped is the best for the polishing. Polishing results of quartz glass are evaluated by the use of region-track measure method, and some polishing rules are presented.
Development of Face Magnetic Inductor with Permanent Magnets for Deburring Using MAF Process
Authors: Ko S.L. , Baron Yuri M. , Park Jung Il
Published: March 2009

Several types of inductors with permanent magnets for deburring using the MAF process
were investigated in this paper. The magnetic intensity of each system was measured at working
gap to determine the proper system. Using the inductor with a permanent magnet, which was
designed and manufactured as a result of the investigation, the heterogeneity of the finishing
process and the variations in the location of the magnet poles and the amount of the powder were
analyzed during the deburring process. The characteristic curve was calculated from the
experimental data and used to compare the performance of each inductor. Under similar conditions,
the permanent magnet inductor showed superior performance compared to the electromagnetic
inductor in the deburring process.
Three-Dimensional Simulation of Liquid-Solid Two-Phase Flow Inside the Abrasive Water Jet Nozzle
Authors: Huang Chuan Zhen , Hou Rong Guo , Wang Jun , Lu X.Y. , Zhu Hong Tao
Published: March 2009

Three dimensional simulation of the velocity field of solid-liquid two-phase flow inside
the abrasive water jet nozzle was studied by the computational fluid dynamics software (CFD). The
complicated velocity field and vectorgraph of the flow in the abrasive water jet nozzle was obtained.
In the course of the simulation, the Syamlal-O’Brien model was used to decide the inter-phase drag
exchange coefficient. The velocity vectorgraph simulation results indicate that the highest flow
speed is occurred at the inlet of the mixing chamber and the flow speed is gradually decreased along
the direction of the nozzle axis and got to the lowest speed at the outlet of the nozzle. And also the
flow speed in the cross section of the mixing chamber is gradually reduced along the radial
direction of the cross section and got to the lowest speed in the verge of the chamber. The
comparison of simulation result for the velocity field of water and abrasive exhibits that the velocity
of water in the mixing chamber is three or four times higher than that of abrasive.
Numerical Simulation and Prediction of Surface Heterogeneity in Diamond Turning of Single-Crystalline Germanium
Authors: Yan Ji Wang , Fan Yu Feng , Yoshihara Nobuhito , Kuriyagawa Tsunemoto , Yokoyama Shoji
Published: March 2009

This paper deals with the mechanism of surface heterogeneity due to crystallographic
anisotropy effects in diamond turning of single-crystalline germanium. A microplasticity-based
numerical simulation model was proposed, in which the effects of tool geometry and machining
conditions can be involved. Two coefficients were introduced to compensate the Schmid factors of
two different types of symmetrical slip systems. Simulation of ductile machinability was conducted
on two crystallographic planes (100) and (111), and the simulation results were consistent with the
experimental results. It was indicated that the simulation model can be used to predict the
brittle-ductile boundary change with machining conditions and crystal orientations of germanium.
Experimental Investigation of Brittle to Ductile Transition of Single Crystal Silicon by Single Grain Grinding
Authors: Huo Feng Wei , Jin Zhu Ji , Zhao Fu Ling , Kang Ren Ke , Guo Dong Ming
Published: March 2009

Grinding of single crystal silicon may be achieved by two modes of material removal: ductile mode and brittle mode. Knowing of the brittle to ductile transition point at which the grinding process changes from the brittle mode to ductile mode is critically important for the realization of ductile mode grinding. This paper uses a new single grain diamond grinding method developed recently by the authors to investigate the brittle to ductile transition during grinding of single crystal silicon in all around. The results indicate that there exist four stages of brittle to ductile transition as the depth of cut is reduced: firstly, the surface cracks outside the grinding groove disappeared, secondlycracks on the bottom of the groove disappeared, then the lateral cracks ceased in the subsurface region, and finally the median crack is suppressed beneath the grooves. It is not until the depth of cut reaches the last transition point that a crack-free groove can be produced, therefore, the last transition stage is decisive. The critical depth of cut delineating the brittle to ductile transition point derived based on this criterion is 40 nanometers, which is much lower than that based on surface cracks.
Development of a Rubber-Bonded Grinding Wheel - Studies on Aspherical Grinding -
Authors: Yoshihara Nobuhito , Yan Ji Wang , Kuriyagawa Tsunemoto
Published: March 2009

Aspherical surfaces are an important technology in optical instruments. Until now, only
improvements in form accuracy and surface roughness of aspherical surfaces have been investigated.
However, when the surface roughness becomes low, the small waviness of the surface becomes
marked. This small waviness is termed “Nano-topography.” Nano-topography causes grinding marks
and reduces the accuracy of an optical instrument. Nano-topography is caused by the vibration of a
grinding wheel during the manufacture of the surface. This paper will reveal how a rubber-bonded
grinding wheel has been developed to absorb that vibration. The dressing of the grinding wheel was
also investigated. As a result, it is possible to eliminate the generation of nano-topography.
Discussion on the Radial Superresolution of the Two-Photon Microfabrication
Authors: Wei P. , Zhu Yu , Tan Q.F. , Duan G.H. , Gao G.H.
Published: March 2009

In order to improve the radial superresolution of the two-photon microfabrication, the
superresolution diffraction theory was introduced in detail. The theoretical analysis of the
photosensitive resist based on the exciting power and concentration of free radical was given.. And
the superresolution diffractive optical element was applied in the two-photon microfabrication
system. Simulation results indicated that the radial superresolution of the two-photon
microfabrication can be improved with the superresolution diffractive optical element.
Bending Deformation of Pure Titanium Plate in CO2 Laser Forming
Authors: Okuda Koichi , Sugie Y. , Nunobiki Masayuki
Published: March 2009

This study deals with behaviour of bending deformation in CO2 laser forming process of titanium. CO2 laser forming technique was applied for a pure titanium plate with thickness of 1 mm to aim the development of new bending process. The experiments of laser forming were carried out with a CO2 laser machine. The bending angle and the temperature of workpiece were examined under the condition of various laser power, feed speed and laser spot diameter. Based on the experimental results, it was found that the bending deformation behaved greatly depending on the laser power and the laser spot diameter. The bending angle increased with an increase in the laser power. The bending direction tended to change from the laser irradiation side to its opposite side when the large laser spot diameter was applied.
Investigation of Toughness and Wear Resistance of a-C/a-C:Cr Multilayer Coatings
Authors: Ma Kung Jeng , Chien Hsi Hsin , Chao Choung Lii
Published: March 2009

Alternated a-C/a-C:Cr coatings were made by DC magnetron sputtering from graphite
and Cr target in an argon discharge. Mechanical and tribological properties were measured by
indentation, scratch and pin-on-disc test.
The critical scratch load of a-C/a-C:Cr multilayer coatings for total failure is approach 100 N.
The friction coefficient remains within the range of 0.08-0.1 at loads between 10 and 40 N during a
pin-on-disc wear test. The wear depth only reaches 0.6 μm after a one hour wear test. The greater
compliance and fracture toughness of the a-C/a-C:Cr multilayer coatings allows greater strains or
strain energy to be stored before coating failure, and hence significantly improves wear resistance
Adsorption and Effectiveness of Different Antibiotics on Pure Hydroxyapatite (HA) with Controlled Porosity
Authors: Chai Feng , Hornez Jean Christophe , Blanchemain N. , Neut C. , Descamps M. , Hildebrand H.F.
Published: March 2009

The advantages of local antibiotic administration - high local levels with low systemic toxicity - are nowadays recognized as an efficient way for anti-infection therapies consecutive to the orthopaedic implant surgery. Aimed at assessing the feasibility of using Hydroxyapatite as drugdelivery carrier in addition to its well-known bone reconstruction bioactivity, a pure HA ceramic with specific internal pore size and porosities was under our investigation. The antibiotic release and antibacterial effect were determined by UV spectrophotometry and disk agar diffusion assays after impregnation with different antibiotics and their release in different solvents. No differences were found after the ATB impregnation under normal pressure or under vacuum conditions. The influences of impregnation time on the duration of the ATB release and on the antibacterial efficiency were more evident for Vancomycin than for Ciprofloxacin and Gentamycin. In all cases, the ATBs penetrated micro-porous and meso-porous HA samples and showed significantly stronger and longer anti-bacterial effects than dense HA samples. The ATBs releases in PBS were relatively slower and the antibacterial effectiveness subsequently prolonged with respect to those in human plasma. All tested HA samples with or without ATB impregnation exhibited very good biocompatibility as shown by cell proliferation tests. It revealed a promising perspective for further improving the antibacterial efficiency by other surface functionalization methods for achieving a controllable drug delivery with antibiotic loaded HA.
Titanium-Reinforced Polytetrafluoroethylene Membrane Combined with Inorganic Polyphosphate Induces Exophytic Bone Formation in Rabbit Calvaria
Authors: Kim J.S. , Na S.Y. , Kown Y.H. , Park J.B. , Chung J.H. , Cho M.I. , Herr Y.
Published: March 2009

The purpose of this study was to examine if the application of titanium-reinforced expanded
polytetrafluoroethylene(TR-ePTFE) membrane combined with bovine bone mineral(BBM) soaked
in inorganic polyphosphate promotes exophytic bone formation in rabbit calvaria. For this purpose,
a total of 8 rabbits were used, and rectangular decorticated calvaria sites were created using a round
carbide bur. In the control group, rectangular parallelepiped-shaped TR-ePTFE membranes
(RPTPMs) were filled with BBM soaked in saline and placed on the decorticated sites and fixed
with metal pins. In the experimental groups, RPTPMs were filled with BBM soaked in 4%, 8% and
16% inorganic polyphosphate prior to fixing with metal pins. Animals were sacrificed at 4 and 8
weeks after surgery, and new bone formation was assessed by histomorphometric as well as
statistical analysis. The results indicated that at 8 weeks, all the experimental groups demonstrated
exophytic bone formation. At 8 weeks, the 8% polyphosphate group revealed the most new bone
formation (p<0.05). On the basis of these findings, we conclude that inorganic polyphosphate has a
promoting effect on bone regeneration, possibly by enhancing osteoinductivity of the decorticated
wound area and osteoconductivity of the carrier material, but not much as we expected.
Mesenchymal Stem Cell Proliferation and Morphological Analysis on Interconnected Macroporous Structures
Authors: Teixeira S. , Fernandes H.M. , de Boer J. , Ferraz M.P. , Monteiro F.J.
Published: March 2009

Calcium phosphate ceramics are widely used as bone substitutes since they are
biocompatible and bioactive. Given that their chemical composition is close to natural bone,
calcium phosphate ceramics are promising bone substitute materials in orthopaedics, maxillofacial
surgery and dentistry. Hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most
commonly used calcium phosphates, because their calcium/phosphorus (Ca/P) ratios are close to
that of natural bone and they are relatively stable in physiological environment. Furthermore, other
critical parameters must be accomplished when designing a biomaterial for bone regeneration,
namely: pore size, shape and interconnectivity [1]. Porosity is one of the most important factors
since it influences the adhesion, migration nutrient supply and ultimately, proliferation of
mesenchymal stem cells. In this study, HA scaffolds with controlled porosity were obtained and
their capacity to support human and rat mesenchymal stem cells attachment and proliferation was
evaluated.
Fabrication of Porous Ti6Al4V with Designed Structure by Rapid Prototyping Technology
Authors: Li J.P. , Wilson C. , Wijn J.R. , van Blitterswijk Clemens A. , de Groot K.
Published: March 2009

Rapid Prototyping (RP) technique was used to prepare porous Ti6Al4V with designed
structures. Firstly, a 3-D interconnected porous wax mold with uniform pore size and porosity was
designed by computer aided design (CAD), and fabricated by 3-D printing machine, then an aqueous
Ti6Al4V slurry prepared from Ti6Al4V powder and binders was cast in these molds. The green
bodies were subjected to drying, debinding and finally sintering at a high temperature and a high
vacuum to obtain porous Ti6Al4V. Optical microscopical observation, scanning electronic
microscopical observation, mechanical test were performed on the obtained porous Ti6Al4V with
regard to the porous structures and mechanical properties. The porous Ti6Al4V made by RP
technique posses designed structure with uniform pore size, porosity and interconnection. With the
computer aided design, it is easy to improve the mold structure with predicted or controlled
macrostructure and microstructure according to the custom requirement.
Friction Characteristics of Poly(vinyl Alcohol) Hydrogel as an Articular Cartilage Biomaterial
Authors: Pan Yu Song , Xiong Dang Sheng , Chen Xiao Lin
Published: March 2009

Poly(vinyl alcohol) (PVA) hydrogel is a promising articular cartilage biomaterial. In this
paper, the effects of different variable factors on the friction coefficient of Poly(vinyl alcohol)
(PVA) hydrogel were investigated when sliding against stainless steel ball by ball-pan tribometer.
Factors included lubrication condition, sliding speed, diameter of stainless steel ball, and load. It
was shown that the free water in PVA hydrogel has an excellent lubrication on the counterparts. The
friction coefficients have little difference between dry and lubricants lubrication condition at initial
friction test. With the friction test time prolonged, friction coefficient of PVA hydrogel under dry
condition increased rapidly. Friction coefficient decreased with the increase of sliding speed and the
diameter of stainless steel ball, and increased with the increasing load. The rising rate of friction
coefficient at low load region is obviously larger than that at high load region.
Research on Residual Stress and Surfacial Morphology of Bio-Functionally Gradient HA-ZrO2–Ti Coatings
Authors: Ning Cheng Yun , Wang Ying Jun , Chen Xiao Feng , Ye Jian Dong , Wu Gang , Zhao Na Ru , Wei Kun , Ren Li , Liu Hua Guo
Published: March 2009

In the present study, Functionally gradient HA-ZrO2-Ti coatings (FGC) on Ti6Al4V were prepared by the plasma spraying process. The residual stress and surfacial morphology of coating were studied by X-ray diffraction and scanning electron microscopy with an energy dispersive spectroscopy. The results showed that: (1) the residual stress of FGC is 72.1Mpa, much lower than that of single HA coating, (2) The surfacial morphology of the FGC showed typical characteristics of plasma-sprayed coating, no microcracks was observed because of its the thermal expansion matched between the gradient coating and substrate.
Preparation of Poly(L-lactic Acid) Hybrid Membrane with Silicon-Ion-Releasing Ability
Authors: Maeda Hirotaka , Ishida Emile Hideki , Kasuga Toshihiro
Published: March 2009

A novel poly(lactic acid) (PLA)/calcium carbonates hybrid membrane containing siloxane
was prepared using aminopropyltriethoxysilane (APTES) for biodegradable bone guided
regeneration. The PLLA in the membrane was an amorphous phase. By heating the membrane at 100
°C for 1 h, the PLLA in the membrane crystallized. Numerous pores of 0.5-1 ,m in diameter were
newly formed at the surface. After soaking the membranes before and after heat-treatment in
simulated body fluid, the amount of silicon species in SBF released from the membrane after
heat-treatment was higher than that before heat-treatment. A test of osteoblast-like cellular
proliferation on the membrane showed the membrane after heat-treatment has much higher
cell-proliferation ability than that before heat-treatment.
Effect of Apatite Nanoparticles on Remineralization of the Demineralized Human Dentin
Authors: Tan Zhen , Wu Hong Kun , Mo An Chun , Chen Zhi Qing , Li Yu Bao
Published: March 2009

The aim of this study was to evaluate the remineralizing potential of demineralized
human dentin treated with Y/HA nanoparticles (doping Y with 5mol %) and HA nanoparticles
suspension and whether dentin could be remineralized by HA. Human crown dentin was
demineralized with EDTA for 4 hours, and then subjected to remineralization condition. The ability
of these matrices to remineralize was determined by SEM, AFM and calcium levels in the
remineralized tissue were measured by atomic energy spectrum analysis. The results showed that
Y/HA and HA nanoparticles remineralized the demineralized dentin surface; these demineralized
matrices treated with Y/HA nanoparticles remineralized to a greater extent than those treated HA
nanoparticles. The differences in both the quality and quantity, as defined by Yttrium iones leading
to changes in characterization of the apatite crystals might be important in effecting the ability of
this tissue to remineralize. This work suggested that apatite nanoparticles caused remineralization of
dentin and the yttrium ions substituted in the apatite structure might enhance their remineralization
potential.
Surface Modification of Nanosized Biphasic α-TCP/HA Powders
Authors: Pan Li Li , Li Yan Bao , Zou Chao , Weng Wen Jian , Cheng Kui , Song Chen Lu , Du Pi Yi , Zhao Gao Ling , Shen Ge , Wang Jian Xun , Han Gao Rong
Published: March 2009

Stearic acid was utilized to modify biphasic alpha-tricalcium phosphate
(α-TCP)/hydroxyapatite (HA) powders in the ethanol. The results showed that the dispersion of
biphasic α-TCP/HA powders (BCPs) in non-polar matrix improved. And the released content of
Ca2+ and PO4
3- of the BCPs soaked in the NaAc-HAc buffer solution (pH 5.0) was almost same as
that before modification. Stearic acid could modify the suface properties of BCPs and would not
obviously affect their biological characteristics, which affords a good groundwork of application of
calcium phosphates powders.
Hydrothermal Synthesis of Nano-Crystalline Hydroxyapatite
Authors: Niu Jin Long
Published: March 2009

Natural biological hard tissues are nanocomposites of proteins and calcium hydroxyapatite (HAp) with superior strength and bioresorbabilities. Nanometer scale hyroxyapatite is the key material to manufacture bioresorbable bone substitute. An attempt was conducted to synthesis nano-crystalline hydroxyapatite with a hydrothermal chemical method. The prepared nano-crystalline HAp was characterized for its phase purity and nanoscale morphological structure by XRD, TEM and FTIR. The obtained results indicated that hydrothermal synthesized nano-crystalline HAp was pure single phased HAp with a diameter of 20 to 50nm and length range between 50 to 200nm and each HAp particle was observed to be a monocrystal of HAp. It’s suggested that hydrothermal treatment may be an effective method to get pure and nice crystallized nano-sized stoichiometric hydroxyapatite.
Caries Inhibitory Activity of the Nano-HA In Vitro
Authors: Meng Xiang Cai , Lv Kui Long , Zhang Jiu Xing , Qu Da Li
Published: March 2009

The purpose of this study is to examine the inhibitory effects of nano-HA on the caries-inducing properties of a four-organism bacterial consortium in vitro. A series of in vitro anticarious experiments have been carried out by using a continuous culture system. Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus, Lactobacillus rhamnosus have been chosen as the experimental bacteria. After 48 hours, the dental plaque surface structure is observed with the scan electron microscope and the bacterial colonization was evaluated on dental plaque. The results show that Spherical nano-HA and mixed nano-HA are proved to be effective in anticarious experiments, and especially spherical nano-HA is more striking. It is able to damage the formation of biofilms (dental plaque), postpone or end the process of acid generation of bacteria metabolism. After 7 days, the demineralization of the enamel has been detected by using TEM. The spherical nano-HA might have a remineralization to early caries to prevent and decrease caries.
Osteogenic Activity of MG63 Cells on Hydroxyapatite/Collagen Nanocompsosite under Pressure/perfusion Culture
Authors: Yoshida Teruaki , Kikuchi Masanori , Koyama Yoshihisa , Takakuda Kazuo
Published: March 2009

The purpose of this study is to analyze osteogenic activity of human osteoblastic MG63
cells on the bone-like self-organized hydroxyapatite/collagen (HAp/Col) nanocomposite sponge
cultured by a pressure/perfusion technique using collagen sponge as a control. Histological
analyses, alkaline phosphatase (AlkP) protein analysis and real-time polymerase chain reaction
(PCR) analyses for AlkP and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) to evaluate the
osteogenic activity of MG63. The MG63 cells were attached well and showed good proliferation on
the HAp/Col sponge as well as in the control. The MG63 cells on HAp/Col sponge demonstrated
higher osteogenic activity than those on the control. The results suggested that the HAp/Col sponge
is expected to be a good scaffold for bone tissue engineering.
Nano-Hydroxyapatite/Polymer Composite Scaffold for Bone Tissue Engineering
Authors: Wang Hua Nan , Li Yu Bao , Zuo Yi , Cheng Lin , Wang Yuan Yuan , Li Hong
Published: March 2009

Nano-hydroxyapatite/polyamide66 (n-HA/PA66) composite scaffolds are prepared using
phase separation and phase separation in combination with particle leaching, and both the
composite powder and paste are used as starting materials. The composite is characterized by IR
and XRD. The micro-architecture of the scaffolds is observed by SEM, and the mechanisms that the
formation of the porous structure follows have been investigated preliminarily. The results show
that scaffold prepared by phase separation in combination with particle leaching method using
composite powder as starting material possesses controllable porosity and interconnectivity, as well
as good mechanical strength comparable to human cancellous bone, suitable for being the
tissue-engineered scaffold for load-bearing bone repair. Furthermore, scaffold made by phase
separation using composite paste as starting material exhibits an anisotropy both in morphology and
mechanical properties, which indicates the potential of guiding cell seeding, distribution and new
tissue formation in preferential direction.
Confocal Raman Spectroscopic Analysis of Phase Transformation and Residual Stresses in Ce-TZP/Al2O3 Nanocomposite for Biomedical Applications
Authors: Yamada Kiyotaka , Nawa Masahiro , Pezzotti Giuseppe
Published: March 2009

Zirconia ceramics have been widely used for new generation of bearing materials in
biomedical applications. In this context, a zirconia-matrix, stabilized with cerium oxide and
dispersed with fine alumina particles (Ce-TZP/Al2O3 nanocomposite) was recently developed and
this material experienced significant improvements in both fracture toughness and strength above
the standard mechanical performance of monolithic zirconia. In this paper, we used confocal Raman
spectroscopy to provide quantitative assessments with high spatial resolution of phase structure and
residual stress fields developed in the Ce-TZP/Al2O3 nanocomposite. According to confocal Raman
spectroscopy, we have directly visualized patterns of phase transformation and residual stress fields
stored on the very surface of the material around an indentation print. These spectroscopic
assessments may open a perspective in understanding the micromechanical behavior of the
Ce-TZP/Al2O3 nanocomposite when subjected to local surface impingement and shocks.
Preparation and Characterization of the Microspheres Comprised of Atelocollagen and BCP
Authors: Wei Qing Rong , Lu Jian , Zhao Hui Chuan , Jiang Bo , Zhang Bo , Gu Zhong Wei , Zhang Xing Dong , Chen Ji Yong
Published: March 2009

In order to develop a bone-filling material with osteoinductive potential, a composite micorspheres of collagen molecules and biphasic calcium phosphate (BCP) was prepared by utilizing emulsion polymerization and the intrinsic self-assembly of collagen. The prepared microspheres were analyzed by granularity test, scanning electron microscopy (SEM), infrared spectra (IR) and enzymatic digestion experiment. The results showed that the collagen matrix of fibrils was reconstituted in the droplets, and the native triple-helix structure of collagen was still maintained. The study provides an effective way to prepare microspheres of collagen and BCP composite.
Antibacterial Activity of Silver-Hydroxyapatite/Titania Nanocomposite Coating on Titanium against Oral Bacteria
Authors: Mo An Chun , Xu Wei , Xian Su Qin , Li Yu Bao , Bai Shi
Published: March 2009

This study was focused on evaluating the bactericidal and anti-adhesive efficacy of
silver-hydroxyapatite/ titania nanocomposites (nAg-HA/TiO2) coating on titanium against oral
bacteria. Porphyromonas gingivalis, Prevotella intermedia and Fusohacterium nucleatum and
Streptococcus mutans were used. Antibacterial activity of nAg-HA/TiO2 coating was investigated
quantitatively using film applicator coating method and titanium plates incubated with bacteria were
prepared for SEM to observe the adherence of oral bacteria. The viability of each type of bacteria on
the antibacterial film was suppressed to about 10% after anaerobic incubation for 3 hours. Image of
SEM demonstrated that bacteria on sandblasting surfaces were relatively confluent whilst on coated
surfaces fewer bacteria were observed. Adherence of bacteria on nAg-HA / TiO2-coated surfaces
compared with uncoated surfaces was remarkably decreased.
Preparation and Characterization of n-HA/PA66/CS Biocomposite
Authors: Xiang Hong Zhao , Li Yu Bao , Mu Yuan Hua , Wang Xue Jiang , Wang Hua Nan , Li Hong
Published: March 2009

Nano-hydroxyapatite/polyamide66/chitosan composite (n-HA/PA66/CS) was prepared by
a co-precipitation method, and was characterized by TG/DTG, TEM, IR, XRD and Universal
mechanical testing machine. TEM test showed that some rod like crystals were formed and
distributed uniformly into polymer matrix, with a size of about Φ30nm×80nm. IR and XRD
analysis showed that some chemical bonds and electrostatic interaction existed between n-HA and
polymers. TG/DTG curves indicated that the composites possessed a talent of high heat-resistance.
The compressive strength of composite changed with different content of three compounds, the
maximum compressive strength of composite (70MPa) could be acquired.
Synthesis and Characterization of n-HA/PVA/Gel Composite
Authors: Wang Ming Bo , Li Yu Bao , Xu Feng Lan , Zhou Gang , Cheng Lin
Published: March 2009

A unique composite consisted of nano-hydroxyapatite (n-HA), poly (vinyl alcohol) (PVA)
and gelatin (Gel), was prepared and characterized by Fourier transform infrared absorption
spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and burning
test. The homogenicity of the composite was evaluated, and the presence of interior chemical bond
was confirmed and discussed. Mechanical strength and water absorption of the prepared composite
were investigated, respectively. The results show that n-HA/PVA/Gel composite has good
homogeneity, similar mechanical properties to natural cartilage and excellent in vivo
biocompatibility.
Bioactive Hydroxyapatite/ Polyvinyl Alcohol Composite for Repair and Regeneration of Articular Cartilage
Authors: Zheng Yu Dong , Wang Ying Jun , Chen Xiao Feng , Lu Hua Ding , Liu Qing
Published: March 2009

In this work, a new kind of bioactive PVA/HA hydrogels use as artificial cartilage were prepared by in situ sol-gel synthesis method. Simulated experiments were performed to evaluate and compare the bioactive ability and properties of the hydrogels in simulated body solution. PVA/HA Cartilage implants were developed and used to repair articular cartilage defect in rabbit knee. The macroscopic and histological observation of animal experiments displayed that the implanted hydrogels combined tightly to ambient tissues, and some bone-like tissue grew into the bottom of the implants from the base-bone to form more deep-set binding.
The Influence of Bovine Serum Albumin on the Biomimetic Calcium Phosphate Coating of Bioactivated Titanium
Authors: Wu Yao , Yang Bang Cheng , Lu Jian , Gu Zhong Wei , Zhang Xing Dong
Published: March 2009

In this study, bovine serum albumin protein (BSA) was introduced to investigate the co-precipitation process of calcium phosphate and BSA on bioactivated Ti. Commercially pure titanium were bioactivated firstly, and then immersed in a highly supersaturated stable calcium phosphate (Ca-P) solution at three different conditions. The samples designated as Ti-C, Ti-C-CB, and Ti-C-B for control. The samples were evaluated by SEM with EDX, XRD and XPS. The co-precipitation of BSA protein and Ca-P influenced the morphology of the crystals of Ti-C-CB significantly. In terms of the immersion in the Ca-P solution containing BSA, the co-precipitation of Ca-P with BSA on the surface of Ti-C-CB was a chemical process rather than simple physical adsorption, which was most possibly achieved by the linkage of –COO− groups to Ca-P. Such coprecipitated interaction led to the formation of a tight, dense and uniform Ca-P coating.
Biocompatability of Precipitation-Enhancing Anodic Oxidation on Titanium as Implant Material
Authors: Oh Keun Taek , Kim Kyoung Nam , Han Dong Hoo , Chung M.K. , Hwang S.H.
Published: March 2009

The composition of the electrolytes used in the process of anodic oxidation was modified to
generate the novel anodic oxidation. The surface topography of the novel anodic oxidation showed that the
pore/crater structures with the precipitants attached over the surface were observed in SEM. The physical
properties and biocompatibility of the surface with the novel anodic oxidation were compared with that of
anodic oxidation and machined surface of titanium. XRD, Bioactivity in a simulated body fluid, cell
proliferation, and MTT test were performed to evaluate the differences among different surfaces.
In Situ Monitoring the Growth of HAP Crystal on the Surface of Ti/TiO2 in SBF with a Quartz Crystal Microbalance
Authors: Zhu Zhi Hong , Tong Hua , Jiang Tao , Shen Xin Yu , Wan Peng , Hu Ji Ming
Published: March 2009

The Pre-Ca procedure was applied to the titanium surfaces before immersion in the SBF
to accelerate the apatite precipitation. The process of apatite formation on the titanium surfaces was
investigated by using scanning electron microscopy (SEM). A QCM system was applied to
quantitatively monitor the apatite formation process using biomimetic method in situ in real time
and to estimate the effect of pre-calcification in the biomemetic process effectively combined with
SEM technique.
XPS studies of Hydroxyapatite Powders by Grafting Octadecyltrichlorosilane
Authors: Yang Chun Li , Weng Wen Jian , Du Pi Yi , Shen Ge , Han Gao Rong
Published: March 2009

It is known that the organic molecules can provide effective means to tailor the surface properties of the biodegradable ceramic. In this paper, a long-chain organic silane- Octadecyltrichlorosilane(OTS) was used as coupling agent and hydroxyapatite(HA) was the candidate ceramic. Samples were characterized by means of XPS technique. XPS results indicated that Si-O-P bond was formed on the HA surface after surface-modification, which means OTS was grafted onto the HA surface through covalent bond , XPS results also showed that by regulating the surface-modification process Si(Atomic percentage) content on HA surface could be changed from 0 to 2.88%.
Control of Calcium Phosphate Precipitation in Hydrogel
Authors: Kamitakahara Masanobu , Ogata Shinichi , Tanihara Masao , Ohtsuki Chikara
Published: March 2009

Electrophoresis can transport ions more rapidly and directionally in a gel. The controlled precipitation of calcium phosphates in an agarose gel was attempted by electrophoresis of calcium and phosphate ions. Wells were prepared on an agarose gel. A CaCl2 solution was placed in wells on the positive side and a Na2HPO4 solution in wells on the negative side. A potential of 100 V was then applied. White precipitates appeared in the gel after 11 min. The white area initially became larger and more intense with increasing time. However, after longer periods, the white area decreased and became weaker, before disappearing after 45 min. Spinous precipitates with a diameter of about 500 nm were obtained when the gels were collected after 20 min. The precipitates were characterized as particles of calcium phosphate.
Synthesis of Novel High Silicate-Substituted Hydroxyapatite by Co-Substitution Mechanisms
Authors: Stephen J.A. , Skakle J.M.S. , Gibson Iain R.
Published: March 2009

Silicate substituted hydroxyapatite bioceramics have been shown to enhance bone repair in vivo compared to hydroxyapatite (HA), although the amount of silicate ions that can be substituted alone into the hydroxyapatite structure is limited to approximately 5.2 wt%, or 1.6 wt% Si. This study describes the substitution of greater levels of silicate ions via co-substitution of silicate ions with trivalent yttrium ions, without resulting in the formation of any secondary phases. This substitution mechanism involves a coupled substitution of yttrium and silicate ions for calcium and phosphate ions, respectively, and enables a level of silicate substitution up to approximately 9 wt%. Two different substitution mechanisms result in subtle differences in the crystal structure. When the mechanism xY3+ + xSiO4 4- was used, a small decrease in the a-axis, but no change in the c-axis, of the unit cell compared to HA was observed. In contrast, when the mechanism x/2Y3+ + xSiO4 4- was used, a significant increase in the c-axis of the unit cell was observed, compared to HA. XRF analysis and FTIR spectroscopy supported the proposed substitution mechanisms. These novel substitution mechanisms not only enable greater levels of silicate-substitution in HA to be prepared, but also allow the production of compositions with the same level of silicate substitution, and with subtle differences in chemical structure.
Promotion of Bioactive and Corrosion Resistance by Electrolytic Piezoelectric Ceramic
Authors: Lin Chi Min , Yen Shiow Kang
Published: March 2009

Biocompatibility of metallic implants and bone in orthopaedic surgery plays an important
role in long-term survivor of the prosthetic implant fixation. However, titanium and its alloys do not
bond to bone in the early stage of implantation (<6 months). On the other hand, titanium alloy
undergoes electrochemical exchange and releases metallic ions in the physiological environment,
which is believed to be the cause of implant failure. Cathodic electrolytic deposition is an important
method in ceramic processing. In this paper, the nanocrystalline BaTiO3 coating were prepared by
electrolytic deposition process. According to the XRD results, we can clearly identified that
electrolytic deposition Barium titanate hydrate gel annealed at 350°C for 1 hr will form to BaTiO3,
and its grain size about 4.85 nm. From dynamic cyclic polarization tests, we can found that dense
BaTiO3 coated effective improved corrosion resistance of Ti substrate than untreated. From
immersion tests, we can found that BaTiO3 exhibited excellent bioactive.
Preparation of a Bioactive Xenograft
Authors: Kim Hyung Sup , Lee Yong Keun , Lim Bum Soon , Chung Chong Pyong , Rhee Sang Hoon
Published: March 2009

The method which gives a low crystalline hydroxyl carbonated apatite forming ability to originally non-bioactive high crystalline hydroxyapatite surface was newly developed. The granules of trabecular bovine bone, which had a size range from 212 to 1000 μm, were defatted, deproteinized, and then heat-treated at 1000 oC for 3 hours to remove organics completely. They were treated with the mixed solution of calcium chloride and calcium hydroxide in Soxhlet’s apparatus at 100 oC for 3 days and then dried completely. Low crystalline hydroxyl carbonated apatite was observed to occur on the surface of high crystalline hydroxyapatite granules after soaking them into the simulated body fluid (SBF) for 1 week. This method is likely to have a potential to be used as a new process to give a bioactivity to originally non-bioactive materials.