bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-Time Oxidation of a NiAl(Zr) Bond Coat Thermochemically Deposited on a Nickel-Based Superalloy
Authors: Hamadi Sarah , Bacos Marie Pierre , Poulain Martine , Zanna Sandrine , Maurice Vincent , Marcus Philippe
Published: March 2009

Thermal barrier systems, used for turbine blades, are made of a nickel-based superalloy, a
nickel aluminide bond coat layer and a ceramic thermal barrier. The aim of the present work is to
study the initial stages of oxidation of the AM1/NiAl(Zr) system. It is currently of prime importance
to characterize the initial thin oxide layer that covers the bond coat prior to the topcoat deposition.
Indeed, the adhesion of the thermal barrier layer and the lifetime of the system are partly influenced
by the substrate pre-heating oxidizing treatment. In order to determine the contribution of zirconium
during this intermediate temperature range oxidation, the AM1/NiAl(Zr) system was heat treated at
950°C, in two vacuum conditions, that were close to the industrial ones. The compositions of the
extreme surface of the nickel aluminide and of the thermally grown oxide were investigated by Xray
photoelectron spectroscopy. In particular, these experiments allowed us to detect zirconium at
the surface of the system and to determine its oxidation state.
Background to the Topics Concerned in the Present Papers
Authors: Kettunen Pentti O.
Published: March 2009

The present background description concentrates on the structure of wood xylem, on the mechanical strength properties under monotonic external loading, on the degradation of the structure of wood and somewhat also on the influence of thermal treatment (heat treatment) on the structure and properties of wood. The presentation is largely based on a recent publication of the author /1/. In this manner, the description tries to illustrate the status of the present general knowledge in the fields, into which the present papers bring new results and ideas for a better understanding of the structure and behavior of wood.
Effects of Temperature and Sheet Thickness on Formability of AZ31 Magnesium Alloy
Authors: Ricci P. , El Mehtedi Mohamad , Barone L. , Spigarelli Stefano
Published: March 2009

The formability of AZ31 magnesium alloy sheets, with two different thicknesses, has been investigated at room temperature and 250°C by means of Nakazima tests. The different straining conditions have been studied by using sheet blanks with several length to width ratios, and Forming Limit Diagrams were then obtained with and without using lubricant. As expected, an increase in temperature was observed to enhance the formality of the alloy. The formability increases also by increasing the thickness as well as by using Teflon foil as lubricant. The microstructure of the deformed samples was analysed by means of light optical microscope.
Long-Term Heat Treatments on Ti6Al4V-SiCf Composite. Part I - Microstructural Characterization
Authors: Donnini Riccardo , Kaciulis Saulius , Mezzi Alessio , Montanari Roberto , Testani Claudio
Published: March 2009

The microstructure of Ti6Al4V-SiCf composite, in as-fabricated condition and after long-term heat treatments (up to 1,000 hours) in the temperature range 400 - 600 °C, has been investigated by means of high-temperature X-ray diffraction (HT-XRD), energy dispersion spectrometry (EDS), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Particular attention was paid to the strains, arising during heating, and to the micro-chemical evolution of fibre-matrix interface. Micro-chemical examinations evidenced that a thin TiC layer has formed between the fibre carbon coating and the matrix during the fabrication process. TiC slows down further diffusion of carbon towards the matrix and guarantees the interface stability also for the most severe treatments examined here.
Monitoring the Crystallization Stages of Silicalite by Positron Lifetime Spectroscopy
Authors: Kajcsos Z. , Kosanovic C. , Bosnar S. , Subotic B. , Major P. , Liszkay Laszlo , Bosnar D. , Lázár K. , Havancsák H. , Luu A.T. , Thanh N.D.
Published: March 2009

In porous media, positron annihilation techniques (PAT) revealed the existence of annihilation modi with long lifetimes connected to structural and extrastructural free volumes acting as trapping centres for o-Ps. Our aim in this work was to study the influence of the synthesis applied for the production of the zeolite framework and the correlation between the trapping pattern and crystallization progress. PAT lifetime (LT) measurements were performed in silicalite-1 samples in various stages of crystallization and a large change was observed in the long components. The results are discussed in connection to the crystallization and the availability of free volume.
Study of the On-Surface Diffusion of the Ternary System Au/Pd/Si (111)
Authors: Hammoudi A. Hakim , Benazzouz C. , Tobbeche S. , Benouattas N. , Boukhalfa N.
Published: March 2009

The ternary system has been built by the deposit of two metal coats (layers), Gold and Palladium on a monocrystalline Silicon substrate of orientation (111). The whole system has been subjected to a vacuum heat treatment, the range of temperatures starts from 100 °C up to 600°C by steps of 50°C and with an annealing time being fixed at 30 min. Both metal layers were successively deposited without breaking the vacuum within the evaporator. The Silicon substrate had undergone beforehand a chemical treatment by the method in the CP4 to prevent it from the Oxygen barrier effect. So, we obtained few series of samples of which the characterization has been carried out by various techniques, namely: the spectroscopy of retrodiffusion of Rutherford (RBS), the diffraction of the X-rays (XRD), the scanning electronic microscopy (SEM) and its incorporated technique of Energy Dispersive X-rays (DEX).
These analyses allowed us to fulfil a study of the interdiffusion
Hydrogen Sensor: Effect of Palladium Thickness and Porous Structure of Silicon
Authors: Lachenani H. , Cheraga H. , Menari H. , Gabouze N.
Published: March 2009

In the present work, the effect of palladium layers thickness and porous structure of silicon on the hydrogen gas sensor was studied. Hence, simultaneous Pd/CHx/PS/Si and Pd/Si structures have been used as a sensing material to detect H2 gas. Comparison with previous study on CHx/PS/Si structure allows to understanding the effect of pores in silicon material and the contribution of palladium in detection of the hydrogen.
Current-voltage and capacitance-voltage characterizations show that the porous silicon structure (Pd/CHx/PS/Si) has higher sensitivity toward H2 gas than that exhibited by silicon sensor despite the presence of palladium (Pd/Si) in both structures. On the other hand, our experiments show that the presence of Pd metal decreases the dynamic response which increases the sensitivity of the sensor.
This result conducts, us to optimize the thickness of deposited Pd layer, therefore different Pd layer thickness ranging from [10 nm to 50 nm] was studied. The feature of the best optimized Pd layer deposited on the surface has been characterized by scanning electron microscopy (SEM).
Finally it appears that both the catalytic property of Pd metal and the presence of pores were found to strongly influence the sensor response in terms of hydrogen sensitivity and response time.
Sm1-xNdxNiO3 Thin Films Deposition by KrF Laser Ablation
Authors: Lafane Slimane , Kerdja Tahar , Abdelli-Messaci Samira , Malek S. , Maaza M.
Published: March 2009

The perovskites RNiO3 (R rare earth ≠ La) are classified as a phase transition metal-insulator. The transition temperature is modulated by the size of the rare earth. The use of compound R1-xR'xNiO3 can vary transition temperature on a wide thermal range depending on the concentration of the two rare earths. The Sm1-xNdxNiO3 (x = 0.45) thin layers have been carried out on (100) silicon substrates by KrF laser ablation (λ = 248 nm, 25ns) at two different fluences 2 and 3 Jcm-2. The oxygen pressure and the target-substrate distance have been maintained at 0.2 mbar and 4 cm respectively. The deposition temperature has been set at 500 ° C. The obtained layers were characterized by X-ray diffraction, atomic force microscopy and Rutherford back scattering diagnostics. The resistivity Measurements were carried out by the conventional four-probe method. The XRD spectra revealed the presence of an ideal cubic perovskite phase. The RBS analysis showed that the deposited layers are rich in oxygen. A correlation between the morphology properties of the deposited layers and the plasma dynamics studied by fast imaging has been found.
Phase Explosion in Silicon and Titanium Targets Irradiated by Third Harmonic Nd-YAG Pulsed Laser
Authors: Kerdja Tahar , Yahiaoui K. , Bendib A. , Malek S.
Published: March 2009

In this work, the combined diagnostic measurements of ablated material by scanning electron microscopy of the craters and ion time of flight analysis have been employed to study the interaction of third harmonic Nd-Yag laser with silicon and titanium target. Evidence for the transition from normal vaporization to phase explosion has been obtained, showing an abrupt increase in the mass ablation rate beyond a laser intensity threshold and round-shaped micrometer-sized cavities found on the irradiated areas. Ion time of flight analysis is used to estimate the surface temperature under near threshold ablation conditions.
Optical Properties of the Strained Layer Superlattices (GaAs)6/(GaP)m(001) (m=2, 4 and 6)
Authors: Hamidani Ali , Bennecer B.
Published: March 2009

First principles calculations, by means of the full-potential linearized augmented plane wave method within the local density approximation, were carried out for the optical properties of the strained layer superlattices (GaAs)6/(GaP)m(001) (m=2, 4 and 6). The calculated imaginary part of the dielectric function agrees well with the available experimental data. The assignment of the structures and the peaks in the optical spectra and band structure transitions are investigated in detail. Our results indicate that the anisotropy in these materials is mostly due to the tensile strain in the GaP layers.
Structural Properties of Al-Cu Thin Films after Heat Treatment
Authors: Lallouche S. , Debili M.Y.
Published: March 2009

In this work we are interested by the decomposition behaviour after heat treatment at 500°C of nanostructured Al-Cu deposits, prepared by radio frequency (13.56MHz) magnetron sputtered from composite targets. The use of X-ray diffraction leads to the characterization of different structures and the estimation of grain size and dislocation density. The grain size of the films is found to increase with annealing. The dislocation density is observed to exhibit a decrease trend with annealing temperature which leads to a reduction in the concentration of lattice imperfections
A specific thermal study of the Al-Cu deposits, by combined thermal analysis (TDA/TG) permit to follow the structural behavior of the deposits with heat treatment. For Al-7.21at%Cu deposit, the exothermic peak convolution may be due to the elimination of micro deformations present in the sample.
Effect of SF6 Cover Gas Humidity and Concentration on Efficient Protection of Molten Magnesium
Authors: Zhang Ya Qin , Motegi Tetsuichi , Tanabe Fumi , Abe Daisuke
Published: March 2009

Sulfur hexafluoride (SF6) is widely used by the magnesium industry as a component of cover gas mixtures, which reacts with the melt and forms a protective film on the melt surface. In this study the dew points of the air that acts as carrier gas for SF6 was varied from 203K to 273K, and the effect of the SF6 cover gas humidity and concentration on the efficient protection of molten AZ91D magnesium alloy was investigated in temperatures ranging from 903K to 973K. Gas chromatography (GC) combined with ion chromatography (IC) were used to identify the chemical constituents of the by-products present in the protective atmosphere, while. X-ray photoelectron spectroscopy (XPS) and Auger electron Spectroscopy (AES) were used in the characterization of the protective films formed on the melt. The results indicate that the quantity of SF6 to protect molten Mg from burning decreased with decrease in the humidity of the cover gas XPS showed that the films formed in all atmospheres with different dew points were composed of MgO, MgF2 and MgSO4. However, in cover gases with higher dew point, the amount of MgO of the film tended to increase, due to the dissociation of MgSO4 of the film into H2 and SO4-2 in the presence of moisture, which lead to the destruction of the protective film and oxidization of the melt.
POSS/TiO2 Nanohybrids as Sun Protection Factors for Skin Changes Caused by Ultraviolet A Radiation
Authors: Chen Xiao Dong , Wang Di , Li Xuan Dong , Liu Yu , Hu Li Jiang
Published: March 2009

Based on (3-methacryloxypropyl)-Polyhedral oligomeric silsesquioxane (MP-POSS) (MP), vinyl-POSS (VP), (3-glycidoxypropyl)-POSS (GP) and modified with 5, 10, 15, 20 and 25 wt-% titanium tetrabutoxide (TTB), three hybrid nanofilms (f-MPT, f-VPT and f-GPT) were prepared using hydrolytic condensation and crosslinking. The transparency of the films was measured at the ranges of ultraviolet A (UV-A) (320-400 nm) spectrum which can cause a much greater risk of skin changes. The average transparency (AT) values of three films were about 65-78% (320-350 nm) and 85-89% (350-400 nm), which implies that these films indeed can provide a physical barrier for blocking the UV-A absorbed into the skin, indicating functionality of the POSS/TiO2 materials as the sun protection factor (SPF) ingredients in a sunscreen. The AT values of three films were in the order of f-MPT>f-GPT>f-VPT due to complete-cage structures of building blocks (POSS) and the size of organic branches covalently bonded to the silica network in the molecular structures. This indicates that VPT powder might be significantly better to selected for the SPF. The TTB addition results in the hybrid structure containing TiO2 which causes a decrease in the AA radiation from sunlight. Lower transparency of the films containing 25 wt-% TTB fractions is ascribed to more amounts of TTB in the modified films.
Influence of Pore Size on Enzymes Adsorption in Mesostructure Cellular Foams (MCFs)
Authors: Na Wei , Wei Qi , Zou Ze Chang , Wang Zhi Hong , Li Qun Yan , Nie Zuo-Ren
Published: March 2009

Mesoporous silica materials are attractive candidates for enzymes immobilization due to their high surface area, tunable pore size, large pore volume and biocompatibility. In this work, two different enzymes, papain, a small globular enzyme with molecular diameter of 3.6nm, and catalase, a relatively larger enzyme with molecular diameter of 10.4nm were introduced into the pores of siliceous mesostructed cellular foams (MCFs) that had a large cellular pores of 29nm and a small window size of 12nm, respectively. The amount of adsorbed enzymes was found to be dependent on the molecular size of enzymes. The amount of adsorbed catalase was more than two times that of adsorbed papain, suggesting that MCFs with large pores is a suitable host for large enzymes adsorption. The blocking of pores which resulted from aggregation of enzymes in the windows of MCFs and the higher leaching of enzymes form MCFs may be the reason of lower papain adsorption capacity in MCFs.
Preparation and Performance of Polypyrrole Film with Micro-Antennal Morphology for Medical Biology
Authors: Lin Cheng , Mai Man Fang , Xiong Zhao Xian , Xue Hao , Qiu Hong
Published: March 2009

PPy film with micro-antennal morphology was prepared by potentio-static method without any templates directly onto the surfaces of iron, platinum and gold-plated plastic sheets, respectively. Morphology of PPy film was observed with scanning electron microscopy, and its electrochemical properties were determined by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Attention was paid to the influence of reaction time, potential value, types of substrates, types and conconcentrations of electrolyte on the morphology and electrochemical properties of PPy film. Stable PPy film with thriftily long antennae was obtained on different substrates with good electrochemical properties. The film was applied for a prototype of biosensor, in which bioactive substance of glucose oxidase was immobilized.
Preparation, Microstructure and Properties of Biodegradable Aliphatic Polyesters by Using Nontoxic Magnesium Catalysts
Authors: Liu Lian , Wei Zhi Yong , Wang Pei , Qi Min
Published: March 2009

The aim of this paper is to present a synthesis method of biodegradable aliphatic polyesters by the ring opening polymerization of lactones catalyzed with nontoxic magnesium compound. Poly(DL-lactide-co-ε-caprolactone) copolymers were prepared by the copolymerization of DL-lactide and ε-caprolactone using magnesium octoate as a catalyst. Microstructure and crystallization and thermal properties of the obtained polymers were investigated by NMR, XRD and DSC.
Hydroxyapatite Deposition by Alternate Soaking Technique on Poly (Vinyl Alcohol)-Coated Poly (ε-Caprolactone) (PCL) Substrate
Authors: Li Ling Li , Li Guang , Jiang Jian Ming , Guo Yue Wen
Published: March 2009

Biomineralization on surface-modified poly (ε-caprolactone) (PCL) through an alternate soaking process was investigated. A poly(vinyl alcohol) (PVA)-coating on PCL substrate prepared by repetitive adsorption/ drying in an aqueous PVA solution could accelerate hydroxyapatite (HA) deposition while PVA-PCL soaked in aqueous solutions containing Ca2+ and PO3-4 ions alternately. Fourier transform infrared (FTIR) and X-ray diffraction of the apatite verified the formed hydroxyapatite in these processes exhibited a close resemblance with calcium phosphates (HA, Ca10(PO4)6(OH)2). It was also found that the amount of HA formed increased with both soaking with both soaking cycles and deposition amount of PVA on PCL. This study suggested that simple PVA coating on PCL substrate could serve as a novel way to accelerated HAP formation via alternating soaking.
Corrosion Behaviours of Mo Modified Ti6Al4V Alloy in Hank’s Solution
Authors: Fan Ai Lan , Zhi Cheng Gang , Tian Lin Hai , Qin Lin , Tang Bin
Published: March 2009

The Mo surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo modified Ti6Al4V alloy was investigated by X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). The Mo modified layer contains Mo coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo modified Ti6Al4V alloy reveals that the outmost surface of the Mo modified Ti6Al4V alloy is composed of pure Mo. The electrochemical corrosion performance of the Mo modified Ti6Al4V alloy in 25°C Hank’s solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that the self-corroding electric potential and the corrosion-rate of the Mo modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 25°C Hank’s solution.
Negative Synergism between Corrosion and Wear of Nickel-Free Austenitic Stainless Steel in Artificial Body Solution
Authors: Zhou Guang Hong , Zhang Yue , Ding Hong Yan
Published: March 2009

The reciprocating corrosion wear behavior of a nickel-free austenitic stainless steel 13Cr24Mn0.44N flat against a Si3N4 ceramic counter ball was investigated in two kinds of aqueous such as artificial body solution and distilled water by using the ball-on-flat configuration with 300 μm amplitude at various normal loads. The worn surfaces of the new stainless steel were observed by scanning electron microscopy (SEM). Elements valence in wear scars were also detected by X-ray photoelectron spectroscopy (XPS). The influences of the load and aqueous media on the friction coefficient and wear resistance of the new stainless steel were analyzed. It is clear that the friction coefficient decreased in both aqueous with the load increasing. The lubricative surface film formed on the wear scars in the artificial body solution could reduce the friction coefficient, and result in a lower wear loss in the artificial body solution than that in the distilled water, which demonstrates a negative interactive effect between wear and corrosion.
Electrospinning of Sodium Alginate with Poly(ethylene oxide), Gelatin and Nanometer Silver Colloid
Authors: Kong Qing Shan , Yu Zi Sen , Ji Quan , Xia Yan Zhi
Published: March 2009

In this study, biocompatible polymer poly(ethylene oxide) (PEO), gelation (denatured collagen) and nanometer silver colloid was added to the electrospinnning solution of alginate sodium to get anti-bacterial nanofiber mats. The morphology and mechanical properties of the electrospun mats have been investigated. Smooth fibers with diameters around 300 nm were obtained from 4.0 % solutions of varied alginate/PEO/gelation proportion. The anti-water property of the electrospun mats has been improved by crosslink with glutaraldehyde acetone solution and aqueous calcium chloride and ethanol.
Effect of the Surface Energy on the Biomineralization Behavior and Cell Compatibility of Carbonated Hydroxyapatite
Authors: Zhu Qing Xia , Wu Jian Qing , Feng Qing , Wang He Ping
Published: March 2009

Carbonated hydroxyapatite (CHA) and hydroxyapatite (HA) were prepared by the wet chemical method. The contact angle was measured to calculate the surface energy. The biomineralization process in SBF solution of HA and CHA were investigated in vitro. The cell attachment and proliferation behavior of CHA and HA were compared by the cell culture experiments. The results show that the polar component of surface energy of B-type CHA is higher than that of HA. Osteoblastic cells attach and proliferate very well on the surface, which indicates the excellent cell compatibility. The CHA have high bioactivity owing to rapid formation of hydroxyl-carbonate-apatite (HCA) mineralized layer on the biomaterial’s surface in SBF.
Ring Opening Polymerization of ε-Caprolactone Catalyzed with Magnesium Lactate
Authors: Liu Lian , Wei Zhi Yong , Wang Pei , Qi Min
Published: March 2009

The aim of this paper is to present a synthesis method of poly(ε-caprolactone) by the ring opening polymerization of ε-caprolactone catalyzed with nontoxic magnesium lactate. The results indicated that Mg(Lac)2 is a catalyst with moderate activity for the polymerization of ε-caprolactone. Effects of the catalyst and reaction temperatures on the microstructure of the ε-caprolactone and L-lactide copolymers were investigated by means of 13C-NMR spectroscopy. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness.
The Application of Aqueous Span 80 Composite Material in Methane Absorption and Explosion Suppression
Authors: ZHANG Zengzhi , Gu Na , Zhang Ji Fei
Published: March 2009

This paper aims to design a sort of aqueous atomization absorbing material which can absorb mine gas under coal mine to decrease the methane concentration and reduce the explosion hazard. The material was composed of water as matrix, Span 80 as methane absorbent, and inorganic salt as additive. Methane the main component of mine gas was used as model of mine gas. The influence of concentration of inorganic salt on absorption and the effect of different compound materials made of Span 80 and inorganic salt on absorption were studied using Head Space Gas Chromatography to determine the content of methane absorbed. Explosion chamber was used as experiment system to simulate mine gas explosion. The explosion suppression effects of absorbing materials were studied preliminarily in explosion chamber using the maximum explosion pressure and residual methane content after explosion as parameters. The results indicate that the absorbing material can absorb more methane than water and can partly inhibit the explosion of the mixture of methane and air.
In Situ Synthesis and Characterization of β-Tricalcium Phosphate/Na Doped 58S Bioglass Composite by Sol-Gel Technique
Authors: Li Xiang Nan , Chen Xiao Ming , Hu Wei Lan
Published: March 2009

In situ synthesis technique of β-tricalcium phosphate(β-TCP)/ Na-doped 58S bioglass composite powders were investigated. Firstly, the β-TCP ultra-micro powders are synthesized via wet chemical method. β-TCP/Na doped 58S bioglass composite powders were synthesized in situ by sol-gel technique, using tetraethyl orthosilicate(TEOS), triethyl phosphate(TEP), calcium nitrate tetrahydrate(Ca(NO3)2•4H2O), sodium nitrate(NaNO3) as starting materials. The composite powders were characterized by XRD, EDX　and SEM. The bioactivity of the synthesized powders was analyzed by immersion studies in simulated body fluid (SBF). The results show that the composite powders are made up of good crystalline β-TCP and amorphous bioglass, and it was conformed that the material had good osteoproduction and bioactivities, that is an indication of bioactive potential in vivo. It is believed that the β-TCP/ Na-doped 58S bioglass (58SN) composite by sol-gel technique in situ could be a desirable biomaterial for preparing scaffold of bone tissue engineering.
Effects of Alkali and Heat Treatment on Apatite Forming Ability of a Micro-Arc Oxidized Ti6Al4V Alloy
Authors: Wang Ming Run , Yang Sen , Wang San Jun
Published: March 2009

To further improve the bioactivity of Ti6Al4V alloy and to accelerate bone growth, the porous TiO2 coating containing calcium and phosphate prepared on Ti6Al4V alloy substrate using micro-arc oxidation (MAO) technique was treated in 5M NaOH aqueous solution at 60 °C for 24 h and followed by a heat treatment at 400 °C for 1 hour (termed as MAONH). The experimental results showed that Ca2+ and P5+ easily precipitated on the MAONH coating and formed a thicker apatite film. The reason could be ascribed to hydrolysis of CaTiO3, which resulted in appearance of large numbers of Ca2+ and OH- ions within coating.
Construction of Tissue Engineered Skin with VEGF-Modified Human Mesenchymal Stem Cells and Acellular Dermal Matrix
Authors: Zhang Xiang Rong , Liu De Wu , Guo Guang Hua , Peng Yan
Published: March 2009

The development of skin tissue engineering provides a noninvasive method for skin restoration. Unfortunately, the lack of a vascular plexus leads to greater time for vascularization compared with native skin autografts and contributes to graft failure. Our purpose was to construct tissue-engineered skin with VEGF- modified human bone marrow mesenchymal stem cells (hMSCs) as well as acellular dermal matrix(ADM) in vitro , Thus by increased vascular endothelial growth factor expression, which could prospectively improve vascularization of tissue-engineered skin for wound healing applications. To reach this aim, hMSCs were isolated and cultured with density gradient centrifugation combined with attachment culture method in vitro. Liposome- mediated gene transfer was used to generate a population of hMSCs overexpressing the gene encoding VEGF165. Then VEGF- modified hMSCs were seeded onto the surface of ADM. The experimental results showed that ADM we prepared has good compatibility with MSCs, the cells in ADM grew and proliferated well in vitro and the tissue - engineered skin with VEGF- modified hMSCs and ADM has been successfully constructed.
Bio-Effects of Nano-Titanium Dioxide on Lungs of Mice
Authors: Zhang Yan Yan , Tao Jie , He Pin Ting , Tang Yu Xin , Wang Yue Qin , Zheng Ming Bo
Published: March 2009

To evaluate the acute lung toxicity of intratracheally instilled nano-titanium dioxide (TiO2) in Kunming mice, healthy adult Kunming mice were randomly grouped by their body weights (5 mice in each group). The lungs of mice were intratracheally instilled with 1 mg/kg•bw or 10 mg/kg•bw of nm-TiO2. The control group was intratracheally instilled the same volume physiological brine. After exposure of 1, 7, 14 and 28 days, the bronchoalveolar lavage (BAL) fluid and lung tissue were collected. The indexes in BAL fluid were examined. Lung tissues were assessed by histopathology. The results showed that all indexes of 10mg/kg•bw groups were obviously higher than those of the control group and the group of nano-1mg/kg•bw. Activities of LDH on the 1st, 7th, 14th and 28th day post-exposure (pe), contents of MDA on the 1st, 7th and, 14th day pe and TP on the 1st and 7th day pe as well as the amount of leukocyte on the 1st and 7th day pe of 10mg/kg•bw groups were significantly different compared with control groups (P<0.05).There were no obvious changes observed in the activity of ATP within groups (P>0.05). Histopathology found that lungs of 10mg/kg•bw groups presented great increase in pulmonary inflammation. Many TiO2 particles were still clearly found in the interstitium at 28 days pe. In contrast, low-dose instillation had a low risk potential for producing adverse pulmonary health effects. We conclude that the inflammatory reaction gradually eased after 28 days pe. Under the same experimental condition, the effect of lung injury was severer in high-dose nano-TiO2 than low-dose nano-TiO2.
Effect of C2H2 Flow Rate on the Deposition of Zr-ZrC-ZrC/DLC Gradient Nano-Composite Film on Biomedical NiTi Alloy
Authors: Ma Fu Qiu , Liu Xi Liang , Liu Dong , Li Li , Zheng Yu Feng
Published: March 2009

Zr-ZrC-ZrC/DLC gradient nano-composite films have been prepared on the NiTi substrates by the technique of plasma immersion ion implantation and deposition (PIIID) combining with plasma-enhanced chemical vapor deposition (PECVD). The influence of C2H2 flow rate ranging from 30 sccm to 50 sccm on the chemical structure, microstructure, mechanical properties and corrosion resistance of resulting thin films are investigated by Raman spectrum, XPS, XRD, friction coefficient test, nano-indentation, electrochemical corrosion test and atomic absorption spectrometry. XPS and XRD results indicate that on the outmost layer, the Zr ions are mixed with the DLC film and form ZrC phase, the binding energy of C 1s and the composition concentration of ZrC depend heavily on the C2H2 flow rate. With the increase of C2H2 flow rate, the content of ZrC and the ratio of carbon sp3/sp2 decreases. The nano-indentation and friction experiments indicate that the gradient composite film at 30 sccm has a higher hardness and lower friction coefficient compared with that of the bare TiNi alloy. The microscratch curve tests indicate that Zr-ZrC-ZrC/DLC gradient composite films have an excellent bonding property with the substrate. Based on the electrochemical measurement and ion releasing tests, we have found that the Zr-ZrC-ZrC/DLC gradient composite films exhibit better corrosion resistance property and higher depression ability for the Ni ion releasing from the NiTi substrate in the Hank’s solution at 37°C.
The Effects of Surfactants on the Granularity of the HA Powder Synthesized by Mechanochemistry
Authors: Yu Tao , Ye Jian Dong , Wang Ying Jun
Published: March 2009

The hydroxyapatite (HA) was synthesized by wet mechanochemical method；the effects of surfactant, such as triethanolamine, polyethylene glycol (200000), sodium hexametaphosphate, polyvinylpyrrolidone (K30), on the particle size distribution of as-prepared HA powder were studied. Results were characterized by means of X-ray diffraction (XRD), Scanning electron microscopy (SEM), Laser Scattering Particle Size Distribution Analyzer. The results show that the addition of surfactants eliminated the agglomeration of the powder and the uniform, fine particles (D10=0.1149μm, D50=0.12551μm, D90=0.1481μm) were obtained with the Triethanolamine (6 wt %) and Sodium hexametaphosphate (4 wt %) respectively. Our work demonstrates applicability of the mechanosynthesis for reproducible and low-cost synthesis of uniform, fine HCA powder in large batch-sizes.
Development and Properties of a New Correction Instrument of Pectus Excavatum
Authors: Hu Yu Ling , Yu Xue Bao , Miao Wei Dong , Liu Gang
Published: March 2009

A new correction instrument of pectus excavatum is introduced which is designed for a minimally invasive technique (Nuss procedure). The instrument was made of pure titanium plates, and finished by machining, surface treatment and so on. The instrument was made up of correcting bar and fixing bar. The mechanical properties of the instrument was measured with electron universal material testing machine, the safety and validity was verified by clinical doctors after being implanted into the patient. Results showed that the mechanical properties of the instrument keep constantly after implantation for two years. It is lighter than the like product, and can lighten the patent’s and the doctor’s operation bearing. It had been applied in national hospitals, and results showed that it was of better biocompatibility, and few complications were found. Clinical treatment effects were satisfactory.
Effect of Hydroxyapatite Nanoparticles of Different Concentrations on Rat Osteoblast
Authors: Xu Zheng Li , Sun Jiao , Liu Chang Sheng , Wei Jie
Published: March 2009

Nano-HAP (10-20nm) were obtained from East China University of Science and Technology. The osteoblasts were primary cultured from rat calvaria and then treated with five different concentrations(20，40，60，80，100µg/ml) of nano-HAP, the osteoblasts without nano-HAP was used as control group. Inhibition ratio, apoptotic rate were evaluated by MTT assay and flow cytometry (FCM), respectively. The specific surface area of nano-HAP was detected by BET. All date were expressed as mean ± standard deviation.Statistical analysis was performed by t test using software SPSS11.0 for Windows. The results indicated that the nano-HAP could inhibit the growth of osteoblasts in a dose-dependent manner. When the concentrations of nano-HAP were 20, 40, 60, 80, 100µg/ml, the inhibition ratio were 2.8%, 22.2%, 26.9%, 38% and 47.7%, and the apoptotic rate were 4.63%, 6.75%, 9.47%, 11.49%, 17.22%, respectively, which were obviously higher than that of control group. The nano-HAP significantly induced apoptosis in osteoblasts. There were the same tendency that the apoptotic and inhibition ratio of osteoblasts were rising with the increasing of the concentration of the nano-HAP. The specific surface area of nano-HAP was 148.140m2/g.
Preparation of Ca-Substituted α-Sialon Eco-Materials by Utilizing Tungsten Molybdenum Bismuth Polymetallic Tailings
Authors: Guo Yu Juan , Lian Fang , Xu Li Hua , Hao Hong Shun
Published: March 2009

This presented a route to utilize the Tungsten Molybdenum Bismuth Polymetallic Tailings in Shizhuyuan of Hunan province to fabricate Ca-substitued α-Sialon eco-materials. The reaction mechanism in carbothermal reduction nitridation process was widely studied by separately considering the effect of sintering temperature and soaking time. Based on the optimized conditions, a composite containing 78% Ca-based α-Sialon has been fabricated at 1600°C for 8h.
Modified PLA Carrier Material and its Performance in Immobilization of Nitrifying Bacteria
Authors: Lai Zi Ni , Cui Ying De , Gao Peng , Chen Xun Jun
Published: March 2009

To prepare the renewable carrier materials for immobilization of nitrifying bacteria, polylactic acid (PLA) dichloromethane solution was added to chitosan aqueous solution, mixed by agitation at a speed of 150 rpm / min. The resultant PLA microspheres were fund to have diameter of 100 ~ 300 μm, thus underwent ammonolysis by a 6 % hexamethylenediamine / n-propanol solution for 8 min, hydroformylation by a 1% glutaraldehyde solution for 3 h, and grafted with 1% chitosan for 24 h, to improve the surface hydrophilic property. The static adsorption was applied for adhesion of nitrifying bacteria to the surface of the carrier, i.e. immobilization of nitrifying bacteria. The removal efficiency of ammonia by the immobilized nitrifying bacteria in wastewater treatment was tested. The results showed that the surface of the microsphere carrier was rough and osteoporosis, therefore it can adhere more nitrifying bacteria. When it was immersed in the suspension of nitrifying bacteria for 8 h, the rate of nitrification by the immobilized nitrifying bacteria reached the highest level and tended to be stable afterwards.
Studies on the Active Oxygen in Zinc Oxides with Different Morphologies
Authors: Xu Xiao Ling , Zhou Zuo Wan , Zhu Wen Jun
Published: March 2009

Active oxygen species generated from semiconductor under irradiation play an important role in decomposing and mineralizing pollutants and undesirable compounds in the air and waste water. The production of superoxide anion (O2－) and hydroxyl radical (•OH) generated in the suspension of zinc oxides with different morphologies and particle sizes were studied in the present paper. Three kinds of zinc oxides, which named tetra-needle like ZnO (T-ZnO) whisker with length of 10~20 μm and basal diameter of 1~3 μm, nanosized ZnO (n-ZnO) with particle size of 20~30 nm and commercial ZnO powder (p-ZnO) with particle size of ~1 μm, respectively, were used in this work. Nitroblue tetrazolium (abbr. NBT) was used to determine the amount of super oxide anion generated from the related zinc oxides, in which NBT can be reduced to insoluble purple formazan by super oxide anion. The amount of hydroxyl radicals was determined by detecting the decreased absorption intensity of Fe(phen)32+ (complex of iron (II) with 1,10-phenanthroline) at 510 nm with UV-Vis spectrophotometer. The results indicated that the most amounts of superoxide anion and hydroxyl radical were detected in T-ZnO whiskers and n-ZnO respectively. The difference between the production amount of superoxide anion and hydroxyl radical can be attributed to the different mechanisms for both of the production and transportation of these two kinds of active oxygens.
Effect of the Superfine SiO2 Powder Content on the Properties of SiC Composites
Authors: Ruan Guo Zhi , Zhang Zhi Hui , Chen Yun Bo
Published: March 2009

In this paper, silicon carbide materials bonded with superfine SiO2 powder were produced using silicon powder, superfine SiO2 powder and different grain grade silicon carbide as raw materials. At the condition of the same content of silicon powder, the effect of the superfine SiO2 powder content on properties of silicon carbide materials after sintered at 1450°C for 3 h in air atmosphere was studied by means of SEM and other analysis methods. The results showed that silicon powder contributes to both sintering by liquid state and plastic phase combination to improve the strength of samples. When the superfine SiO2 powder content is lower than 3.5%, the density and strength of samples increase and porosity decrease with increasing superfine SiO2 powder content. However when the superfine SiO2 powder content is higher than 3.5%, the density and strength of samples decrease and porosity increase with increasing superfine SiO2 powder content. At the same time, sample with 3.5% superfine SiO2 powder has the best oxidation resistance property at 1100°C.
Synthesis of Brookite-Typed Titania from Titanium Chloride Solution
Authors: Okano Satoshi , Yamamuro Saeki , Tanaka Toshiro
Published: March 2009

The brookite-phase TiO2 was prepared by a hydrothermal synthesis of titanium chloride solution. The thermolysis time and the pH value of the solution were controlled during the synthesis. X-ray diffraction experiments showed that TiO2 powders partially containing the brookite-phase were successfully obtained. A higher amount of OH- in the reaction solution was found to be important to obtain the brookite phase because the intermediate complex leading to the brookite phase consumes more amount of OH- than other phases like the rutile.
Effect of TiO2 Nanoparticle on Thermal and Tensile Behavior of Polypropylene/ Polylactic Acid Composite
Authors: Zhang Ying Chen , Huang J.N. , Wu Hong Yan , Qiu Y.P.
Published: March 2009

The role of both nano-sized of plasma treated Nano Titanium Dioxide particles and strain rate on the tensile properties of plasma treated Nano Titanium Dioxide particles/PP/PLA nano-composites filaments (PTNTOPPCF) was studied. Filaments tensile samples of PTNTOPPCF were prepared by a twin screw mixer- twin screw extruder with a particle content of 0.3~1%. The influence of surface treatment of the particles, with and without low-temperature oxygen plasma treatment, on the physico-mechanical properties was studied. The tensile tests were carried out, differential scanning calorimetry (DSC) and SEM were used in this investigation. Tensile tests were done at different strain rates. The addition of plasma treated Nano Titanium Dioxide particles to PP/PLA caused a change in Young's modulus and yield stress of its composites. The experimental results also showed that the strain-rate sensitivity of PTNTOPPCF changed as plasma with and without oxygen treated Nano Titanium Dioxide particles was added to it with different o.w.f.. We found that the models lead to estimates of activation volumes in the range 4−40nm3 for truly nanocrystalline material. Activation volumes were found to changing un-monotonically with oxygen plasma treatment. The findings were found to be in accord with available experimental evidence in both a quantitative and qualitative manner. Deficiencies in the available experimental evidence were noted, specifically in the context of explaining some of the difficulties in comparing theoretical predictions to experimental observation.
Bioavailability and Speciation of Cd, Pb, Cu, and Zn in Sewage Irrigated Soils in the Southeastern Suburbs of Beijing
Authors: Zhang Rong , Fan Wen Hong , Chen Jun , Sun Ru Meng , Zhao Chun Mei
Published: March 2009

The bioavailability of trace metals in sewage irrigated soils in the southeastern suburbs of Beijing, China was examined by using in vitro digestive fluid extraction method. A sequential chemical extraction (SCE) procedure was used to measure the speciation of trace metals in soil samples, including Cd, Pb, Cu, and Zn. The average concentrations of Cd, Pb, Cu, and Zn were 2.23, 37.9, 59.9, and 127.0 mg kg-1, respectively, indicating that the heavy pollution of soils was caused by Cd, Cu, Pb, and Zn which were mainly distributed in the residual phase, whereas Cd was mostly in the carbonate phase. The extraction efficiencies of Cd, Pb, Cu, and Zn quantified by the in vitro digestive fluid extraction method, were lower than those by the SCE procedure, and the extraction efficiencies of both methods followed the same pattern: Cd >Zn>Pb>Cu. The amount of trace metals extracted by using these two methods were positively correlated. Therefore, the in vitro digestive fluid extraction method can be used to examine the bioavailability of soil-bound trace metals.
Low-Temperature Plasma Deposition of Diamond-Like Carbon and III Nitride Thin-Films for Photovoltaic Devices
Authors: Yuan Jin She , Wang Ming Yue , Yu Guo Hao
Published: March 2009

Low-temperature plasma deposition of diamond-like carbon (DLC) and gallium nitride thin-films grown on Si substrate by PECVD was investigated using atomic force microscopy and reflectance spectra for photovoltaic devices application. It was found that the morphological features of the GaN film depend on the substrates under the optimum deposition conditions. The optical band gap of the films was approximately 5.5eV for PECVD DLC and approximately 3.3 eV for PECVD GaN.
Thermoelectric Properties of Bi0.5Sb1.5Te3 Prepared by the Ultrarapid Quenching Process
Authors: Wei Shao Hong , Chen Hui , Wang Zhong , Chu Ying , Zhu Lei , Jian Xu Yu , Yu Hai Jun
Published: March 2009

P-type Bi0.5Sb1.5Te3 thermoelectric materials have been prepared by ultrarapid quenching method with various cooling rates. The microstructures of sample are very different from those prepared by normal cooling. The ultrarapid quenched material was obtained in the shape of foils, the thickness of which were found to vary in the range of 6-20 μm, which corresponds to a cooling rate of about 106 K/S. X-ray diffraction evidenced a microcrystalline structure of the expected composition with a (0015) plane. Increasing the cooling rate, the Seebeck coefficient increase, the electrical conductivity decrease and the power factor rise up to 4.4×10-3 Wm-1K-2 .The highest ZT value of 1.22 was achivedachieved for the materials with the copper roller roration speed 40 m/s in room temperarure.
Analysis and Design of High-Speed Flywheel on Satellite Energy Storage/Attitude Control System
Authors: Zhang Jian Yu , Fu Yue , Zhao Li Bin , Fang Jian Cheng
Published: March 2009

Flywheel rotor structure is one of essential assemblies of the flywheel system used in IPACS. It is significant to ensure the safety of metallic hub and the composite rim under high centrifugal loading induced by the rotation field and the surface pressure produced by the interface misfits. In this paper a 3-D stress analysis model of the flywheel rotor is presented with the finite element analysis software ANSYS and the failure criteria of the materials are discussed to assess the structural strength. Moreover, the key design parameters are investigated briefly to disclose their influences on the stress distribution of rotor structure. At last, an optimum mathematics model with the outer radius of metallic hub, the thickness of each composite ring and the interface misfits as the design variables is presented. Based on the optimum design platform, the series of flywheel rotor structures can be designed systematically.
Copper Electrowinning from Gold Plant Cyanide-Containing Solution
Authors: Wang Bi Xia , Lan Xin Zhe , Song Yong Hui , Li Ying Sheng
Published: March 2009

The electrowinning method for treating high copper cyanide solution was investigated by thermodynamics analysis and experiment. The influences of copper concentration, solution temperature, electrolysis time, current density and flow rate on copper recovery and current efficiency was studied in detail and the suitable operation parameters were chosen. Copper electrowinning from the industrial barren solution with copper concentration of 12.40g/L was performed under the condition of current density of 75 mA/cm2, flow rate of 30mL/min and 50°C for 8 hours. An alloy with copper concentration of 99.87% was obtained at the cathode with total energy consumption 2938KWh/t. The used electrolysis solution added with some fresh cyanide sodium solution can be recycled to leaching process.
Thermodynamics of Oxidation on Pb-Free Solders at Elevated Temperature
Authors: Chen Fang , Du Yun Fei , Zeng Rong Chang , Gan Gui Sheng , Du Chang Hua
Published: March 2009

Based on the available thermodynamic and phase equilibria data, the thermodynamic criteria for oxidation in tin-based lead-free solders under soldering condition was deduced. The dependence of Gibbs free energy on temperature in Pb-free solder oxidation reaction was calculated by applying MATLAB program. The characteristics of oxidation reaction of a varity of solder alloy systems such as Sn-Ag, Sn-Cu, Sn-Sb, Sn-Zn, Sn-Ag-Cu and Sn-Pb eutectic alloys at elevated temperature were analyzed. The results suggested that zinc preferentially oxidized in Sn-Zn solder alloys in the elevated temperature state, while tin preferentially oxidized in the other alloys. The oxidation potential of the Sn-Zn eutectic alloys was higher than that of the pure tin at elevated temperature, whereas the oxidation potentials of Sn-Ag, Sn-Cu, Sn-Sb and Sn-Ag-Cu eutectic alloys were approxiately equal to that of the pure tin. All tin-based Pb-free solder alloys more easily oxidized than the Sn-Pb solder alloys. Oxidizability of these alloys followed in a decreasing order: Sn-Zn＞Sn-Sb＞Sn-Cu＞Sn-Ag＞Sn-Ag-Cu＞Sn-Pb.
Formation Enthalpy, Free-Energy and Activity Coefficients of Sn-Pb Eutectic Solders
Authors: Gan Gui Sheng , Chen Fang , Zeng Rong Chang , Du Yun Fei , Du Chang Hua
Published: March 2009

Based on Miedema’s model, the enthalpy of formation, excess free-energy and partial molar excess free-energy of Sn-Pb binary alloy solders were calculated. The model of the activity coefficient for each component in the solders was established. The diagrams of enthalpy of formation, free energy versus composition and activity versus composition and temperature as well as activity coefficients as a function of composition and/or temperature were drawn. And then the relationship between the activity coefficients of elements Sn/Pb in the solders and temperature was obtained. The approaches to reduction in the volatilization of lead at high temperature were proposed from the point of views that the lead pollution to environment results from its chemical activity in the solder alloys.