bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Adding Organic Solvents on the Phase Behavior in Water/Surfactant/scCO2 Microemulsion in Supercritical State
Authors: Park Ji Young , Lee Chang Ha , Yoo K.P. , Lim Jong Sung
Published: March 2009

Water/CO2 (W/C) microemulsion was formed by sodium salt of bis(2,2,3,3,4,4,5,5-octa fluoro-1-pentyl)-2-sulfosuccinate and the phase behavior of this emulsion was investigated in supercritical state. In addition, the change of the phase behavior of W/C microemulsion was observed when various organic solvents were added into this microemulsion. The added organic solvents are isopropanol, n-propanol, ethanol, methanol, pyridine, 2-methoxyethanol, tetrahydrofuran, acetonitrile, acetone, and 1,4-dioxane. According to the results, the phase behavior of W/C microemulsion depended on the temperature and pressure and the microemulsion was thermodynamically stable in the special range of pressure. In case of W/C microemulsion with organic solvents, the phase behavior of this system was affected by the solubility parameter of organic solvents.
Structural Properties of Potassium Encapsulated in Carbon Nanotubes
Authors: Lee Mi Young , Hwang Ho Jung , Lee Jun Ha , Lee Hoong Joo , Kang Jeong Won
Published: March 2009

We have investigated structural phases of potassium in carbon nanotubes using a structural optimization process applied to an atomistic simulation method. As the radius of the carbon nanotubes is increased, various structural phases ranging from an atomic strand to multi-shell packs composed of coaxial cylindrical shells and helical, layered, and crystalline structures are found to emerge. Numbers of helical atom rows composed of coaxial tubes and orthogonal vectors of a circular rolling of a triangular network can explain multi-shell phases of potassium in carbon nanotubes.
Surface Characterization of Electrochemically Fabricated CuO Doped ZnO Thin Film
Authors: Yoon Jang Hee , Shim Yoon Bo , Cho Chae Ryong , Won Mi Sook
Published: March 2009

In this study, ZnO and CuO doped zinc oxide thin films were cathodically deposited in aqueous zinc chloride solutions in the presence of oxygen on a Pt/Ti/SiO2/Si substrate through an electrochemical reaction. A mercurous sulfate electrode was used as a reference electrode and the counter electrode was a Pt spiral wire. Deposition was carried out in solutions containing Zn2+ ions introduced as ZnCl2 salt at concentrations ranging from 5.0 x 10-4 to 5.0 x 10-2 M. The bath temperatures were controlled from 65°C to 80°C. The oxygen gas was introduced from argon/oxygen mixtures allowing its partial pressure to be fixed along with its concentration in the solution. Doping of CuO was carried out in cupric nitrate or a cupric chloride/0.1M KCl solution. The influence of the Cu/Zn concentration, deposition temperature of a solution, applied cathodic potential and deposition time were optimized. After the potential was applied, the cathodic current reached a steady state within 5 min. The composition, and the characterization of the surface of the films were investigated through X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy.
Growth of Highly Luminescent Silicon Nanocrystals by Rapid Thermal Chemical Vapor Deposition
Authors: Cheong Hea Jeong , Kang Jung Hyun , Kim Jae Kwon , Yong Kim
Published: March 2009

We investigate the growth of highly luminescent silicon nanocrystals by rapid thermal
chemical vapor deposition (RTCVD), employing SiH4 and N2O as source gases. For [N2O]/[SiH4] = 7 ∼ 8 and a growth temperature of 650°C, we obtain the optimized deposition condition for silicon rich oxide (SRO) layer having highly luminescent Si nanocrystals after post-deposition annealing. The cross sectional transmission electron microscope investigation reveals the existence of Si nanocrystals in the SRO matrix. Thus, the photoluminescence (PL) from the SRO layer is attributed
to the quantum confinement effect of carriers in Si nanocrystals. Based on a single layer growth study, we fabricate ultra-thin SRO/SiO2 superlattice having 25 periods on a 3-inch Si wafer. The superlattice has continuous thickness variation from the center to the edge positions of the Si wafer due to inherent wafer temperature variation during growth. Photoluminescence spectra show a systematic blue-shift from a thicker position (center position) to a thinner position (edge position) which is indicative of nanocrystal size control by SRO layer thickness in the superlattice.
MPACVD Nanocrystalline Diamond for Biomedical Applications
Authors: Zheng Chuan Lin , Qi Rong , Yang Wu Bao
Published: March 2009

In the present paper, nanocrystalline diamond films (NDFs) were fabricated on optical glass using microwave plasma assisted chemical vapor deposition (MPACVD). The suitable processing parameters are as followings: methane concentration 3% in argon, total deposition pressure 13.3 kPa, substrate temperature 500 °C. The diamond films were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. In vitro osteoblast cell cultures and platelet adhesion tests were applied to evaluate the biocompatibility of the nanocrystalline diamond films (NDFs). All results indicate that the diamond films exhibit better tissue compatibility and hemocompatibility which are very suitable for biomedical applications.
Microstructure and Mechanical Performances of Plasma-Sprayed Functionally Gradient HA-ZrO2-Bioglass Coatings
Authors: Ning Cheng Yun , Wang Ying Jun , Lu W.W. , Chen Xiao Feng , Wu Gang , Zhao Na Ru
Published: March 2009

For practical applications such as artifical joints and dental implants, there is a strong
demand for hydroxyapatite coatings with excellent performances to ensure long-term fixation. In the present study, functionally gradient HA-ZrO2-Bioglass coatings were prepared using net-energy controlled plasma spraying technology. The structural characteristics andmechanical performances of the coatings were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nanoindentation. The results showed that: (1) Pore sizes and compositions of the coatings changed gradually along the vertical substrate, crystal HA with few calcium phosphates was presented in the heat-treated coatings. (2) Surface of the coating was very rough with nano-sized crystalline grains and micropores; (3) Young’s modulus and hardness changed gradually at the range of coating-Ti6Alo4V interface. Compared with HA coatings, the tensile adhesive strength of the functionally graded HA-ZrO2-Bioglass coatings reached 38.6 MPa, much higher than that of single HA coatings.
Bi2Te3 and Bi2Te3/Nano-SiC Prepared by Mechanical Alloying and Spark Plasma Sintering
Authors: Liu Jing , Li Jing Feng
Published: March 2009

Bi2Te3-based alloys are currently best-known, technological thermoelectric materials near room temperature. In this paper, Bi2Te3 and nano-SiC dispersed Bi2Te3 were prepared by mechanical alloying followed by spark plasma sintering (SPS). Raw powders of Bi, Te and SiC were mixed and mechanically alloyed in an argon atmosphere using a planetary ball mill. The SPS temperature was 623K,
and the holding time was 5 minutes. The samples were characterized by X-ray Diffraction (XRD) and Scanning electron Microscope (SEM). The thermoelectric properties: i.e. Seebeck coefficient, electrical resistivity and thermal conductivity were measured at temperatures from room temperature to 573K,
followed by the evaluation of figure of merit. The results revealed that the SiC dispersion in the Bi2Te3 matrix increased Seebeck coefficient. Although the electrical resistivity was increased somewhat, the thermal conductivity was reduced by the SiC dispersion, indicating that promising thermoelectric materials with enhanced mechanical properties may be obtained in the nano-SiC dispersed Bi2Te3
composites with optimal compositions.
Study on the Synthetic Process of Calcium Borate
Authors: Cao C.E. , Wang Ying Jun , Zheng N.Z. , Xiong C.H. , Shen H.R.
Published: March 2009

Calcium borate used for non-pollution flux of ceramic decoration materials is synthesized by using boric acid and calcium carbonate as raw materials. The effects of reaction temperature, concentration, time, pH value and additive agent on synthesis of calcium borate are studied. The synthesized products are characterized by using DTA, XRD, TEM and SEM. The results show that the better conditions are: synthesis temperature is 80-100°C, the proportion of boric acid and water is0.26 ~ 0.42 to 1(mol), the proportion of calcium carbonate and boric acid is 0.09-0.15 to 1(mol), the pH value is 5 ~ 7, reaction time is 3hs. The synthetic calcium borate is non-crystalline with particle size of 0.1 ~ 0.2 µm, when being calcinated at 300°C, the main crystal phase isCaO·3B2O3·4H2O.
Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics
Authors: Jogad M.S. , Shrikhande V.K. , Dyama A.H. , Udachan L.A. , Kothiyal Govind P.
Published: March 2009

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity.
The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic
the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.
Bioactive Bone Cement Composed of Crystallized Glass Beads and PMMA: Evaluation of Degradation by an In Vivo Aging Test
Authors: Shinzato S. , Nakamura Takashi , Goto Koji , Kokubo Tadashi
Published: March 2009

A new bioactive bone cement (cGBC) consisting of crystallized MgO-CaO-SiO2-P2O5 glass beads and high-molecular-weight polymethyl methacrylate (hPMMA) has been developed to overcome the degradation seen with a previously reported cement (GBC) consisting of MgO-CaO-SiO2-P2O5-CaF2 glass beads and hPMMA. The purpose of the present study was to evaluate the degradation of cGBC using an in vivo aging test, and to compare the degradation of cGBC with that of GBC. Hardened rectangular specimens (20x4x3mm) were prepared from both
cements. Their initial bending strengths were measured using the three-point bending method. GBC and cGBC specimens were then implanted into the dorsal subcutaneous tissue of rats, removed after 6 or 12 months, and tested for bending strength. The initial bending strengths (MPa) of GBC and cGBC were 141.9±1.8 and 144.4±2.4, respectively, while at 6 months they were 109.1±2.6 and 114.1±4.9,
and at 12 months they were 109.1±3.2 and 113.1±3.3, respectively. Although the difference in initial bending strengths was not significant, the bending strength of cGBC was significantly higher than that of GBC at 6 and 12 months, indicating that cGBC is more resistant to cement degradation. The bending strengths of both GBC and cGBC decreased significantly from 0 to 6 months but did not change significantly thereafter. Thus, degradation of cGBC and GBC does not appear to continue after 6 months. We believe that cGBC and GBC are strong enough for use under weight-bearing conditions and that their mechanical strength (especially that of cGBC) is retained in vivo.
Cement from Nanocrystalline Hydroxyapatite: Effect of Sulphate Ions
Authors: Lilley K.J. , Wright Adrian J. , Farrar David , Barralet J.E.
Published: March 2009

Brushite cement is more soluble than apatite cement in physiological conditions and
therefore may be more resorbable in vivo. Brushite cement has been formed previously by mixing β-tricalcium phosphate, water and an acidic source of phosphate ions. However, brushite cement may be formed by the mixture of H3PO4 solution and poorly crystalline precipitated hydroxyapatite (HA). Several additives have been used to alter the physicochemical properties of brushite cement.
In this study sulphate ions where added to the cement system by addition of ammonium sulphate to HA during HA preperation. Sulphate ions were found to alter the structure, composition and mechanical performance of cement.
A Rapid Setting TTCP-DCPD Cement. Study of the Setting Reaction as a Function of Time
Authors: Burguera E.F. , Guitián Francisco , Chow Laurence C.
Published: March 2009

The progression of the setting reaction of a tetracalcium phosphate (TTCP) –dicalcium phosphate dihydrate (DCPD) rapid setting cement was investigated as a function of time. Compressive strength and extent of conversion to hydroxyapatite (HA) were obtained at different incubation times. The results indicated a rapid development of both strength and HA conversion in the early stages of the reaction, which slowed down after 4 h, presumably as a result of HA formation on the surface of the reactants. This hypothesis was supported by scanning electron microscopy examination of cement fracture surfaces.
Accelerated Biomimetic Deposition of Bonelike Apatite on Fibrous Cellulose Templates
Authors: Müller Frank A. , Müller Lenka , Hofmann Ingo , Greil Peter
Published: March 2009

Fibrous cellulose templates are attractive candidates for the use as tissue engineering scaffolds due to their biocompatibility and the adjustable porosity. Nevertheless, a direct bond between cellulose and bone is not formed under physiological conditions. A simulated body fluid solution with a high degree of supersaturation (5*SBF) was used to accelerate the biomimetic formation of bonelike apatite on cellulose templates. After generating calcium phosphate nuclei on
the cellulose fibers in 5*SBF with high Mg2+and HCO3 - concentrations the cellulose templates were immersed in a modified 5*M-SBF which was optimized in respect to crystal growth kinetics by reduced Mg2+and HCO3- concentrations. After 48 hours a hydroxy carbonated apatite (HCA) layer with a thickness of 20 µm was obtained.
Fabrication of Porous Calcium Phosphate Bioceramics as Synthetic Cortical Bone Graft
Authors: Hsu Y.H. , Turner I.G. , Miles A.W.
Published: March 2009

The aim of this study was to fabricate porous Hydroxyapatite/Tricalcium phosphate
(HA/TCP) bioceramics with an adequate degree of interconnected porosity combined with optimal mechanical properties. Porous HA/TCP bioceramics with interconnected porosity and the controlled pore sizes necessary to simulate natural bone tissue morphology were fabricated by a novel technique of vacuum impregnation of reticulated polymeric foams with ceramic slip. By varying the
characteristics of the slips and using foams of different pores per inch (ppi), samples of porous HA/TCP, blocks and granules, with a wide range of pore sizes were successfully manufactured. Functionally gradient materials (FGM) with porosity gradients were also made and no weakness was found at the interface. The pore size of the HA/TCP bioceramics was in the range of 197 – 254
µm (for 20 ppi foam), 143 – 182 µm (for 30 ppi foam) and 105 – 127 µm (for 45 ppi foam). The compressive strengths and the apparent densities of the HA/TCP samples were in the range of 30 –170 MPa and 2.34 – 2.76 g/cm3 respectively. These results indicate that it is possible to manufacture open pore HA/TCP bioceramics with compressive strengths comparable to human bone which could be of clinical interest.
Effect of Calcium Phosphate Glass on Compressive Strength of Macroporous Hydroxyapatite Scaffold
Authors: Kim Yeon Ung , Kim Min Chul , Kim Kyoung Nam , Kim Kwang Mahn , Choi Seong Ho , Kim Chong Kwan , LeGeros Racquel Z. , Lee Yong Keun
Published: March 2009

This study presents the manufacture of macroporous hydroxyapatite scaffolds with a small amount of calcium phosphate glass powder as sintering additives. Hydroxyapatite slurry was prepared by suspending the hydroxyapatite and glass powder in water. Polyurethane sponge was used to produce highly macroporous scaffolds. The rheological characteristic of the slurry was measured to identify the effect of adding calcium phosphate glass powder into hydroxyapatite slurry. Sintered
scaffolds could be repeatedly coated to improve mechanical properties. Scaffolds prepared by single and double replication cycle process were characterized by density, porosity and compressive strength measurements by increasing amount of the calcium phosphate glass powder to the hydroxyapatite slurry, viscosity by increased more than same amount of pure hydroxyapatite, and the capillary force
was similar to pure hydroxyapatite slurry. The compressive strength of the macroporous hydroxyxapatite scaffold containing the calcium phosphate glass powder showed higher value than that of pure hydroxyapatite at single replication cycle. SEM demonstrated that the microstructure of the scaffold became denser with the introduction of the calcium phosphate glass powder. The pore struts were thicker as replication cycle was increased.
Effect of Temperature and Time on the Sintering, Phase Stability, Microstructure and Microhardness of Commercially Available Hydroxyapatite
Authors: Cox F.P. , Pomeroy Michael J. , Murphy M.E.
Published: March 2009

A commercially available hydroxyapatite (HA) was sintered for a number of sintering temperatures and times between 1150°C to 1350°C and 0 to 12 hours respectively. Full density was reached after sintering for 1.5 hours at 1250°C and a maximum microhardness of 4.9GPa was achieved after 6 hours at 1300°C. Significant grain growth occurred but did not seem to influence the
microhardness observed. Significant decomposition was observed after sintering at 1350°C for 1.5 which lead to major decreases in microhardness. An activation energy for grain growth of 286 kJ.mol-1 was calculated which is substantially higher than that previously noted for HA.
Influence of Powder Particle Size of Slurries on Mechanical Properties of Porous Hydroxyapatite Ceramics
Authors: Zhang Yin , Yokogawa Yoshiyuki , Kameyama Tetsuya
Published: March 2009

The effect of different particle sizes on the flexural strength and microstructure of three different types of hydroxyapatite (HAp) powders was studied. The powder characteristics of laboratory synthesized HAp powder (Lab1 and Lab2) were obtained through a wet milling method, and the median particle size and the specific surface area of powders are different with the dryness period. The median particle sizes of Lab1 and Lab2 are 0.34 µm and 0.74 µm, and the specific surface
areas of Lab1 and Lab2 are 38.01 m2/g and 19.77 m2/g. The commercial HAp had median particle size of 1.13 µm and specific surface area of 11.62m2/g. The different powder characteristics affected the slip characteristics, and the flexural strength and microstructure of the sintered porous HAp bodies are also different. The optimum value for the minimum viscosity in these present HAp slip with respect to its solid loading and the optimum amount of the deflocculant were investigated. The flexural strengths of the porous HAp ceramics prepared by heating at 1200°C for 3 hrs in air were 17.59 MPa for Lab1 with a porosity of 60.48％, 10.51 MPa for Lab2 with a porosity of 57.75％, and 3.92 MPa for commercial HAp with a porosity of 79.37％.
HAp Protein Composites Formed by Hydrolysis of α-TCP
Authors: Touny Ahmed H. , Brown Paul W.
Published: March 2009

Composite material composed of hydroxyapatite (HAp) and structural proteins, such as type I collagen or cross-linked gelatins, were synthesized at 37.4°C by hydrolysis of alpha tricalcium phosphate (α-TCP) in the presence of these protein structures. X-ray diffraction (XRD)and isothermal calorimetry were used as tools to evaluate the rate of HAp formation. Rates of HAp formation depend on protein structure. Gelatin enhances HAp formation while collagen delays it.
Changes in pH during the hydrolysis α-TCP are unlikely to have an aggressive effect on the surrounding tissue. The presence of the protein improves the ductility of the HAp/protein composite but it decreases the tensile strength.
Investigation on the In Vitro Degradation and Release Behaviors of Calcium Phosphate Containing Chinese Medicine
Authors: Yu X.H. , Qu Shao Xing , Liu Y.R. , Shen R. , Li Xiao Hong , Zhao Wei , Weng Jie
Published: March 2009

The purpose of this study was to investigate the in vitro degradation and release
behaviors of calcium phosphate powders (Ca/P) containing Chinese Medicine for bone graft. Two kinds of Ca/P powders, one with the Chinese Medicine, Salvia Miltiorrhiza Bunge (SMB) and the other with Polyacrylic Acid (PAA) and SMB, were soaked in simulated body fluid (SBF) for up to 150h. The in vitro release of SMB was measured by UV-VIS spectroscopy. The Ca2+ concentrations
and pH of SBF soaked Ca/P powders were measured by AAS and pH meter. TA and XRD were employed to analyze various Ca/P powders before and after soaked in SBF, respectively. The results demonstrated that a faster SMB release occurred during the first 24 hours, while a slow release was sustained up to150h. Furthermore, the released of SMB in Ca/P-PAA-SMB was faster than that of
Ca/P-SMB. It was concluded that a controllable release of Chinese Medicine from Calcium phosphate may be carried out by the addition of suitable surfactant. Accordingly, calcium ions were released into SBF, which was benefit for bone tissue repairing and reconstructing. Additionally, the TA results showed that there was 1.66% SMB released from Ca/P-SMB-PAA powders. XRD confirmed that various Ca/P powders possessed poorer crystallinity and smaller grain size.
Antimicrobiologic Property Hydrated Amorphous Calcium Phosphates Containing Silver
Authors: Aimanova O.J. , LeGeros Racquel Z. , Sinyayev V.A.
Published: March 2009

The purpose of this study was to determine the microbiologic effect silver (Ag) when incorporated in amorphous calcium phosphate (ACP) prepared from solutions containing calcium, phosphate and pyrophosphate ions. The preparations were obtained from solutions with phosphate/pyrophosphate ratio, P/P2 = 7/3, and characterized as ACP using X-ray diffraction, infrared spectroscopy, nuclear
magnetic resonance and differential thermal analysis. The microbes tested were cultures of E. Coli, St. aureus, Ps aerogunosa, C. diphteroides and C. albicans in media alone (control), with ACP without Ag and with ACP containing different Ag concentrations. Results demonstrated the following: (1) Ag in ACP inhibited the growth of microorganisms in all five cultures, with ACP containing 3-6% Ag giving the greatest antimicrobial effect; (2) sensitivity to the antimicrobial action of Ag differed among the bacteria.
Preparation of Vaterite/Poly(lactic acid) Composites with Excellent Apatite-Forming Ability
Authors: Kasuga Toshihiro , Maeda Hirotaka , Jell G. , Notingher Ioan , Hench Larry L.
Published: March 2009

A new type of ceramic-polymer biomaterial having excellent apatite-forming ability in
simulated body fluid (SBF) was prepared by hot-pressing a mixture consisting of poly(-L-lactic acid)(PLA) and calcium carbonate (vaterite). The composite containing 30% vaterite showed no brittle fracture behavior and comparably high bending strength of ~50 MPa. Apatite layer of several micrometers in thickness formed on its surface after soaking in SBF at 37°C only for 1 day.
Osteoclast culture tests showed that the composite coated with apatite has excellent bioresorbability. After incubation of human osteoblasts, mineralized bone nodule formation was seen on the surface.
Conformational Change of Protein due to Contact with Bioceramic Materials
Authors: Nagai Satoshi , Tsuru Kanji , Hayakawa Satoshi , Osaka Akiyoshi
Published: March 2009

The structural change of bovine serum albumin (BSA) was analyzed by means of
ultraviolet (UV) and circular dichroism (CD) spectroscopy due to in contact with ceramics powders such as Al2O3, SiO2, TiO2, ZrO2, hydroxyapatite and b-tricalcium phosphate. The absorbance of the UV spectra increased for the BSA solution in contact with TiO2, ZrO2 and Al2O3, that is, the BSA solution clouded. This indicated the aggregation of BSA after contact with those ceramics powders.
The CD spectroscopy showed that the ordered secondary structure of BSA was diminished on contact with TiO2 and ZrO2. We discussed the protein adsorption property of ceramics on the basis of the magnitude of the interaction forces between proteins and the bioceramics.
The Effect of Different Surface Modification Agents on the Dispersion of Nano-Hydroxyapatite (n-HA) Crystallites
Authors: Jiang Y.M. , Li Xiao Hong , Feng Bo , Weng Jie
Published: March 2009

The surface of synthetic calcium hydroxyapatite (HA, Ca10(PO4)6(OH)2) was modified through combining freeze-drying, solvent replacement and surface modification methods in an effort to obtain the deaggregative n-HA crystallites. Three surface modification agents: Polyethylene glycol (PEG, Mw: 6000), poly(propyl oxide)-poly (ethyl oxide)-co-poly(propyl oxide)(Pluronic F-127, Mw: 12,000) and poly(d, l-lactide)-co-poly (ethylene glycol) (PELA, Mw: 20,000)were selected. The dispersion of the modified n-HA was characterized by sedimentation time in distilled water, acetone and dimethyl formamide (DMF). The results indicate that the three surface modification agents influence the dispersion of n-HA crystallites in various solvent based on different mechanisms. Transmission electron microscopy (TEM) observation shows that the dried and acetone-replacement powders are composed of needle-like HA crystallites isolated individually. The chosen solvents have a profound effect on the sedimentation time. In distilled water, the dispersion of as-synthesized n-HA crystallites is increased greater by F127 than by PEG. After freeze-drying, the two n-HA particles show homogeneous dispersion in acetone. The colloid stability of freeze-dried HA/PEG, solution-replaced HA/F127 and solution-replaced HA/PELA in DMF were improved significantly. The suspensions remained stable after 30 days with only a blue
transparent sol being observed.
The Effect of Cell Behavior on Apatites with Different Fluorine Contents
Authors: Qu Hai Bo , Waugh O'Neill Rachel J. , Wei Mei
Published: March 2009

Fluoridated hydroxyapatite (FHA) discs with various fluorine contents have been used to study the effect of fluorine content on early-stage cell behavior. FHA powders with fluorine content in the range 0-0.577 (mol F /mol apatite) were pressed into discs and sintered at 1200°C for 1 hour. SAOs-2 rat osteosarcoma cells were cultured on each FHA disc and tissue culture polystyrene (control) with the same seeding density for 4 hours. The cell count was conducted using Alamarblue, and the morphology of cell attachment was observed using environmental scanning electron microscopy. It was apparent that the fluorine content in FHA had significant impact on the early cell behavior.
In Vitro Cytotoxicity Testing of Wood-Based Biomorphic SiC Ceramics
Authors: de Carlos Alejandro , Borrajo Jacinto P. , Serra Julia , González Pio , Liste Sara , León Betty
Published: March 2009

The aim of this study was to test the in vitro cytotoxicity of wood-based
biomorphic Silicon Carbide (SiC) ceramics, using MG-63 human osteoblast-like cells. This innovative material has been recently developed and it exhibits unique mechanical properties towards their application in biomedical technology. In the solvent extraction test the SiC ceramic extracts had almost no effect on cellular activity even at 100% concentration. A similar behaviour was found for Ti6Al4V and bioactive glass, used as reference materials. The results of the cell morphology and the cellular attachment response have also demonstrated that the in vitro performance of these biomorphic SiC ceramics is qualitatively comparable to that produced by titanium alloy and bioactive glass, which seems very promising.
Cytotoxicity Evaluation of Bioactive Glass-Polyvinyl Alcohol Hybrid Foams Prepared by the Sol-Gel Method
Authors: Pereira Marivalda , Al-Saffar Najat , Selvakumaran Jamuna , Hench Larry L.
Published: March 2009

Hybrid bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue engineering were developed through the sol-gel route. Hybrids produced by this route present a high acidic character due to the catalysts added during processing and may also contain residual organics after the drying step. Therefore, an additional cleaning step is necessary to produce biocompatible materials. In this study hybrid PVA/bioactive glass foams were cleaned using various procedures
and cytotoxicity evaluation was conducted. All the cleaning methods used increased the cell viability levels compared to samples not subjected to a cleaning procedure. The most effective cleaning procedure used was the immersion in NH4OH solution. The cleaning procedure changed the composition and pore structure of the final material.
Apatite Layer with Serum Protein as a Suitable Scaffold for Growth of Osteoblast-Like Cell
Authors: Kizuki Takashi , Ohgaki Masataka , Yamashita Kimihiro , Yokogawa Yoshiyuki
Published: March 2009

Autograft, allograft, and biomaterials had been developed for bone regeneration. In
recent year, a tissue engineering technique has been paid much attention for next generation implant. A problem of bone tissue engineering to be solved is a development of the substrate that is suitable for cell adhesion, proliferation, and differentiation. A biomimic scaffold for tissue culture was proposed, and then a cell response on the scaffold was estimated. The scaffold composed by a calcium deficient apatite with an adsorbed serum protein was formed on a ceramic hydroxyapatite (HAp) and surface-modified titanium by a soaking in cell-culture medium supplemented with fetal bovine serum. Excellent results on cell proliferation and cell adhesion were obtained only on osteoblast-like cells (MC3T3-E1). An actin filament in narrow filopodium of the spindle-shaped MC3T3-E1 cells on the ceramic HAp had a regular course. On the other hand, ends of the actin filament of the widely spread cells on the apatite layer with serum protein were scattering. It was suggested that the scattering of the actin end showed an existence of fibronectin, and then tight adhesion would be obtained by the many focal adhesion. Accordingly, the effectiveness of the biomimic scaffold containing serum protein on cell growth was confirmed.
Solution Mediated Effect of Bioactive Glass in Poly (Lactic-Co-Glycolic Acid)- Bioactive Glass Composites on Osteogenesis of Marrow Stromal Cells
Authors: Yao Jun , Radin Shula , Reilly Gwendolen , Leboy Phoebe S. , Ducheyne Paul
Published: March 2009

A previous study demonstrated that the incorporation of bioactive glass (BG) into poly (lactic-co-glycolic acid) (PLGA) can promote the osteoblastic differentiation of marrow stromal cells (MSC) on PLGA by forming a calcium phosphate rich layer on its surface. To further understand the mechanisms underlying the osteogenic effect of PLGA-BG composite scaffolds, we tested whether solution-mediated factors derived from composite scaffolds/hybrids can promote osteogenesis of marrow stromal cells. The dissolution product from PLGA-30%BG scaffold stimulated osteogenesis of MSC, as was confirmed by increased mRNA expression of osteoblastic markers such as osteocalcin (OCN), alkaline phosphatase (ALP), and bone sialoprotein (BSP). The three-dimensional structure of the scaffolds may contribute to the production of cell derived factors
which promoted distant MSC differentiation. Thus PLGA-BG composites demonstrates significant potential as a bone replacement material.
Behavior of Osteoblasts Cultured on Collagen Coated Bioactive Glass
Authors: Andrade A.L. , Valério Patricia , Goes Alfredo , Leite M. Fatima , Domingues Rosana Z.
Published: March 2009

In the current work, we investigated cellular viability, proliferation, and metabolic
activity of rat primary culture osteoblasts in contact with a sample of collagen type I (C) and of this same collagen chemically treated (CTP). The chemical process used here consisted in recover the collagen surface with silica glass obtained from a sol-gel process. The cell viability, the cell death, the alkaline phosphate production and collagen secretion, after 72 hours of incubating the samples with osteoblasts, were measured by MTT assay, propidium iodide, NBT-BCIP assay and SIRCOL
method, respectively. The viability and proliferation of osteoblasts had a significant decrease in the presence of samples when compared to control. The alkaline phosphatase production by the cells had a significant increase in the presence of CTP and collagen secretion by the cells was practically the same when compared to control.
Blood Compatibility of Organic-Inorganic Biomedical Materials
Authors: Osaka Akiyoshi , Yoshioka Tomohiko , Yabuta Takeshi , Tsuru Kanji , Hayakawa Satoshi
Published: March 2009

Organic-inorganic hybrids involving Ti-O bonds were coated on stainless-steel (SUS316L)substrates. Tetraisopropoxide and titanium methacrylate triisopropoxide were employed as the major starting chemicals to provide TiO2-polydimethylsiloxane (PDMS) layers or organotitanium molecular thin layers, respectively. Fourier transform infrared spectra indicated that each layer
contained Ti-O bonds in their structure. The obtained hybrid layers had little effects on the blood-clotting times such as active partial thromboplastin time and prothrombin time. In addition, the number of adhered platelet on the TiO2-PDMS layers depended on the composition, while the organotitanium molecular thin layers suppressed fibrinogen adsorption compared with coating-free SUS 316L substrate.
Fabrics of Polymer Fibers Modified with Calcium Silicate for Bone Substitute
Authors: Kokubo Tadashi , Kawai M. , Masakazu Kawashita , Yamamoto Keiichi , Nakamura Takashi
Published: March 2009

Ethylene-vinyl alcohol copolymer (EVOH), poly(ethylene terephthalate) (PET) and polyethylene (PE) were modified with calcium silicate on their surfaces by a sol-gel method, before or after glow discharge treatment in O2 gas, soaked in a simulated body fluid (SBF) and implanted into knee bone of a rabbit. EVOH and PET formed nano-sized bonelike apatite uniformly on their
surfaces in SBF, without being subjected to the glow discharge, and bonded to the living bone of the rabbit, whereas PE formed the apatite only sparsely even when being subjected to the glow discharge. Three dimensional fabrics with open spaces in various sizes of the former fibers modified with the calcium silicate might be useful as bone substitutes.
Novel Fe2O3-Containing Glass Ionomer Cements: Glass Characterisation
Authors: Hurrell-Gillingham K. , Reaney Ian , Brook I.M. , Hatton P.V.
Published: March 2009

Glass-ionomer cements (GIC) have been used in dentistry for over 30 years. In the past ten years they have also been developed for use as medical grade bone cements. However, concerns have been raised over the biocompatibility of GIC’s in non-dental applications. The release of Al3+ ions from the cement has been related to localized poor bone mineralisation and neurotoxicity. There is a need therefore to develop Al2O3-free cements. One potential route is the substitution of Al2O3 with Fe2O3 in the glass. An Fe2O3-based glass for use in GIC‘s was fabricated. The glass was found to differ considerably compared to the traditional amorphous Al2O3-based glasses. XRD demonstrated a highly crystalline morphology containing magnetite and apatite which was confirmed using electron microscopy. It was predicted that the reduction in Al concentration in the glass would improve the biocompatibility of the resulting cement.
In Vitro and In Vivo Characterization of Various Ferrites for Hyperthermia in Cancer-Treatment
Authors: Kim D.H. , Lee Se Ho , Kim Kyoung Nam , Kim Kwang Mahn , Shim I.B. , Lee Yong Keun
Published: March 2009

Ceramic ferrites can be used to cancer-treatment. Heating of certain organs or tissue up to temperature between 42oC and 45oC preferentially for cancer therapy is called hyperthermia. We synthesized ferrites with various compositions in the system Co1-xNixFe2O4 as hyperthermic thermoseed in cancer-treatment and evaluated their effects on the necrosis of cancer cells under alternating magnetic field in vivo as well as in vitro. When a CoFe2O4 was placed into 0.2 ml distilled
water, the greatest temperature change in this study, Δ T=29.3oC, was observed. More than half of the carcinoma cells were dead after exposure to alternating magnetic field using CoFe2O4, while normal cells were survived more than 60%. The injection of this ferrite particles into the tumor bearing mice was able to suppress the number and volume of tumors. CoFe2O4 is expected the useful hyperthermic thermoseed in cancer-treatment because it exhibited the greatest necrosis of carcinoma cells in vitro and in vivo.
Comparative Investigation of Coprecipitation and In-Situ Synthesis of Nanohydroxyapatite/Collagen Composite
Authors: Lin Xiao Yan , Li Xu Dong , Fan Hong Song , Xiao Yu Mei , Lu Jian , Zhang Xing Dong
Published: March 2009

Hydroxyapatite/collagen (HA/COL) composites were prepared using coprecipitation and in-situ synthesis methods. All these processes yielded nanosize poorly crystallized hydroxyapatite/collagen composites. The low temperature in situ formed composites showed some features of natural bone in phase composition, crystal size and crystallinity. Compare with the composite prepared by coprecipitation synthesis, the composite resulted from a low temperature in
situ synthesis method showed better homogeneity and mechanical properties. It is confirmed that the low temperature in situ synthesis method was an effective way to obtain biomimetic nanoHA/COL composites with good homogeneity and mechanical properties.
Preparation of Cellulose-Carbonate Apatite Composites through Mechanochemical Reaction
Authors: Yoshida Akihiko , Miyazaki Toshiki , Ishida Eiichi , Ashizuka Masahiro
Published: March 2009

Organic-inorganic composites composed of organic polymer and carbonate
hydroxyapatite (CHAp) would be useful bone substitute materials exhibiting low young’s modulus and bone-bonding bioactivity. In this work, such a composite was synthesized from cellulose (CEL)and CHAp through mechanochemical reaction. Homogeneous bulk CEL-CHAp composites were obtained when poly( ε-caprolactone) (PCL) was added as plasticizer with PCL/(PCL+CEL) weight
ratio of 20 wt% or less. The CEL-CHAp composites contained B-type CHAp in inorganic phase. The composites with (CEL+PCL)/(CHAp) weight ratio = 20/80 and 10/90 kept the shape in simulated body fluid (SBF), and showed apatite formation after soaking in SBF. Therefore, the CEL-CHAp composites are expected to be materials with low young’s modulus and bioactivity.
Development of Bioactive Alumina-Wollastonite Composite by Electrophoretic Deposition
Authors: Yamaguchi Seiji , Yao Takeshi
Published: March 2009

Alumina is excellent biomaterial and used in hip prostheses, dental implants and so on. Wollastonite particles were deposited in pores of porous alumina by electrophoretic deposition and an alumina-wollastonite composite was produced. Apatite was formed both inside the pores and on the surface of the composite of the alumina-wollastonite composite by soaking in a simulated body fluid. It was indicated that the deposited wollastonite particles induced the apatite formation. Novel
composite material with both excellent mechanical properties and high bioactivity was developed.
TCP-HA Granules and Impacted Morselized Cancellous Bone Graft Mixes for Acetabular Reconstruction with the Bone Impaction Grafting Technique. A Loaded and Critical Sized Defect Model in the Goat
Authors: Arts J.J.C. , Gardeniers J.W.M. , Welten M.L.M , Verdonschot N. , Schreurs B.W. , Buma P.
Published: March 2009

With the bone impaction grafting technique, a 50/50 volume mix of morselized
cancellous bone (MCB) with TCP-HA granules was used to reconstruct a critical sized acetabular defect in the goat. The biological activity of the MCB/TCP-HA mix was assessed after 15 weeks. Defects filled with 100% MCB, currently the gold standard for this technique, were used as controls. In the 100% MCB defects, a new trabecular bone structure was found in which scarce incorporated remnants of the original graft material were present. In the MCB/TCP-HA defects, MCB was also resorbed or incorporated into new bone. Deep in the MCB-TCP-HA defects, large
TCP-HA granules were generally totally osseous-integrated with new bone. Superficially, more fragmented TCP-HA granules of various sizes were present in the medullar tissue or in the interface with the cement layer. Here, the crushed TCP-HA granules were generally surrounded by osteoclasts and giant cells. The soft tissue interface between the reconstruction and cement did not differ between both groups.
In conclusion, from a biological point of view, this short-term follow-up study suggests that TCP-HA granules can be safely used in a mix with MCB as bone graft extender in acetabular revision surgery with the bone impaction grafting technique.
Development of Hydroxyapatite Thin Film on Titanium Substrate by Electrophoretic Deposition
Authors: You Chang Kuk , Meng Xian Wei , Kwon Tae Yub , Yang Yu Zhong , Ong J.L. , Kim Suk Young , Kim Kyo Han
Published: March 2009

Electrophoretic deposition was used for HA coating on dental implants with different
coating thickness. The HA coating thickness was examined in terms of applied voltage and time, and powder concentration in suspension. Nano-size HA and SiO2-CaO-P2O5-B2O3 bioglass powders were synthesized by sol-gel method. Polyvinyl alcohol (3 wt%) as a binder was resolved in ethyl alcohol, then, nano HA powder was dispersed ultrasonically in the mixture for 15 min and pH was adjusted with HNO3 for positive charging on particle. Titanium substrate was held on cathode and counter electrode was platinum. HA with 0.5 % and 0.03 % of powder concentration was deposited electrophoretically at 10~20 V for 1~20 minutes. The thickness of as-deposited HA layer decreased from nearly 80 µm (0.5 %, 20 V, 10 min) to 4~5 µm (0.03%, 10V, 1 min) as powder concentration, applied voltage and time decreased, respectively. The surface of HA coating layer deposited in lower
powder concentration showed much more homogeneous and relatively dense morphology, in contrast, the surface in thick suspension became rough or porous and was easily spalled. In a co-deposition of HA and bioglass, co-deposited glass played an important role in increasing bonding strength between coating layer and substrate. It is believed that electrophoretic deposition method can be one of
alternatives for relatively thin and easy HA coating.
In Vivo Study of Nacre Pinctada Margaritifera Behaviour in Subcutaneous Site in Rat
Authors: Fricain Jean Christophe , Cognet J.M. , Réau A.F. , Lavignolle B.
Published: March 2009

The objective of this study was to assess the behaviour of nacre pinctada margaritifera (PM) in subcutaneous site in rat and to taste the influence of sterilization on nacre properties. PM discs or powder were sterilized at 120 degree celsius in one bar of pressure during 20 minutes or with gamma ray or in alcohol (70 %) .PM discs or powder were implanted for 3, 6 and twelve weeks in subcutaneous site in rat. The methods used to assess behaviour of PM were: photonic microscopy, scaning and transmission electron microscopy and gravimetry. The results have not shown any diference between the implants. PM is biodegradable, biocompatible but did not show any osteoinductive properties.
New Bioactive Bone Cement Containing Nano-Sized Titania Particles
Authors: Goto Koji , Hashimoto Masami , Fujibayashi Shunsuke , Kokubo Tadashi , Nakamura Takashi
Published: March 2009

Two types of new bioactive polymethylmethacrylate (PMMA)-based bone cements containing nano−sized titania (TiO2) particles were prepared and evaluated to assess the effect of TiO2 content on their mechanical properties and osteoconductivity. We prepared two types of bioactive bone cement, ST50c and ST60c, which contained 50 wt% silanized TiO2 and 60 wt% silanized TiO2, respectively. Commercially available PMMA cement (PMMAc) was used as a
control. The cements were inserted into rat tibiae and solidified in situ. After 6 and 12 weeks, they were taken out for evaluation of osteoconductivity by scanning electron microscopy (SEM), contact microradiography (CMR) and Giemsa surface staining. SEM revealed that ST60c and ST50c apposed to bone directly while PMMAc did not. The affinity index of ST60c was significantly higher than for
the other cements at each time interval. The results showed that ST60c was a promising material, but its mechanical strength should be improved before application in prosthesis fixation.
Alumina Matrix Composites in Arthroplasty
Authors: Piconi Corrado , Maccauro G. , Muratori F.
Published: March 2009

It is well known that the introduction of zirconia into the alumina matrix has a positive
effect on bending strength of the material, and especially on toughness which is the main limit of alumina ceramics. While the many attempts made in the past to develop alumina matrix composites suitable for biomedical applications containing zirconia as a toughening phase (Zirconia Toughened Alumina – ZTA) did not leave the developmental stage, recently ball heads and inlays for THR bearings made out a three phase alumina matrix composite were introduced into the market. In the
alumina matrix of this material both zirconia and exagonal aluminate platelets are distributed, and then it belongs to the class of Zirconia and Platelets Toughened Alumina – ZPTA. Besides ball heads and inlays, also several other innovative orthopedic devices made out this new ceramic biomaterial are in different development stage. This paper reviews the present status of alumina matrix composites in orthopedic application, with special attention to ZPTA.
Third-Body-Wear as a Risk Factor in Joint Endoprosthetics
Authors: Oberbach Thomas , Glien Wilfried , Kaddick Christian
Published: March 2009

It is well known, that wear of the articulation partners of hip joint prostheses affect the long-term durability of the implants in vivo. The wear is dramatically increased if particles in the artificial joint gap act as third body. Those particles can also occur after a fracture of a ceramic component. Until now there are some different guidelines which coupling (metal-polyethylene, ceramic-polyethylene, ceramic-ceramic) should be used for revision. We tested and compared the wear behaviour of a ceramic-PE-pairing and a ceramic-ceramic-pairing under third body wear conditions with alumina-particles in a hip joint simulator.
Development of Silicon Nitride Components for Gas Turbine
Authors: Fukudome Takero , Tsuruzono Sazo , Tatsumi Tetsuo , Ichikawa Yoshihiro , Hisamatsu Tohru , Yuri Isao
Published: March 2009

Silicon nitride is one of the most practical candidates for ceramic gas turbines. The SN282 is silicon nitride material developed by Kyocera for gas turbines. Several new technologies have been developed to achieve materialization of ceramic gas turbines, such as material, fabrication process, evaluation / analysis technology. Recent technology is focused on recession of silicon-based ceramics under combustion gas. Environmental Barrier Coatings (EBCs) are developed to suppress these recession. We have found rare-earth element silicate and yttrium stabilized zirconium oxide (YSZ) have high corrosion resistance to the combustion gas. These materials were applied to the ceramic gas turbine components. The components with EBCs were evaluated in the actual engine tests. We have confirmed that the EBCs effectively work for the recession resistance.