Cytotoxicity study of some Ti alloys used as biomaterial

An implanted material is considered biocompatible, if adverse and uncontrollable reactions don't exist in the biological system. In this sense, biocompatibility tests made in the constituent materials are very important so that the implants have success. The in vitro cytotoxicity tests represent the initial phase of the process, and could be considered as a pre-selection of those materials. In vitro techniques using cell culture have become widely used in the evaluation of biomaterial cytotoxicity, which has contributed to their standardization and the substitution of in vivo tests. This paper shows a study of the in vitro cytotoxicity of two Ti based alloys, Ti–13Nb–13Zr and Ti–35Nb–7Zr–5Ta, in the as-received condition and after heat treated. The results show that the alloys presented no cytotoxic effects in the studied conditions.     

小分子蓝光OLED材料与器件研究进展

有机发光材料(OLED)因其在全彩色平板显示领域的潜在应用价值而受到广泛关注。要实现全色显示,蓝光材料必不可少。尽管已经报到了许多蓝光材料,但是高效稳定的蓝光材料却十分稀少。因此开发具有高发光效率、色纯度、稳定性的蓝光材料必不可少。芴类、苯乙烯类、蒽类蓝光材料由于具有能满足实用化的潜力而成为研究热点。     

Differential cytotoxicity of metal oxide nanoparticles

Concerns about the potential health hazards of nanomaterials are growing. To determine the potential toxicity of metal oxide nanoparticles, human SH-SY5Y neuroblastoma and H4 neuroglioma cells were exposed to Fe₂O₃, CuO and ZnO nanoparticles and their metal ion counterparts (Fe³⁺, Cu²⁺ and Zn²⁺) at a concentration range of 0.01–100 µM for 48 h, under the cell culture conditions: 95% O₂, 5% CO₂, 85% humidity, 37°C. Their ensemble cell viability was determined by MTS cell proliferation assay. A live/dead cell assay was also performed, and cellular images were acquired by a high-content fluorescence microscope and quantified by a novel computerised image analysis protocol. Our data indicated that exposure of these nanoparticles induced differential toxic effects in both SH-SY5Y and H4 cells, and the cells had dose-dependent toxic responses to the CuO nanoparticle insult. In conclusion, the toxic responses of the nanoparticles are complex, and they warrant further in vivo studies. However, it remains to be determined if these nanopartilces have synergistically enhancing or cancelling toxic effects upon both SH-SY5Y and H4 cells.     

8-羟基喹啉金属配合物电致发光材料

有机/高分子电致发光器件是当前国内外平板显示器技术领域的研究热点,8-羟基喹啉金属配合物(8HQM)以其优良的电致发光性能成为研制高效率的有机/高分子电致发光器件的首选材料.针对近十年来8HQM电致发光材料的研究状况,对其电致发光机制、分子结构及发光性能的关系、分子种类及其最新研究进展,进行综述,展望了其发展趋势.     

Fiber-optic Bragg gratings as magnetic field-insensitive strain sensors for the surveillance of cryogenic devices

While conventional electrical resistance strain gages show increasing cross-sensitivities to temperature and magnetic field with decreasing temperature down to liquid helium, it has been found that fiber-optic Bragg grating strain sensors show negligible thermo-optic and magneto-optic effects in cryogenic environments; therefore, they allow reliable strain measurements. These specific application advantages of optical fiber Bragg grating sensors at low temperatures, together with the electrical isolation and low electro-magnetic interference, low thermal conductivity and their multiplexing capability, make them attractive for structural health monitoring in cryogenic devices such as superconductive magnets. In this paper we present low temperature characteristics of fiber Bragg grating-based sensors and address application-based side effects such as induced birefringence.     

Quantitative analysis of the wear and wear debris from low and high carbon content cobalt chrome alloys used in metal on metal total hip replacements

The biological reactions to polyethylene wear debris have been shown to result in osteolysis and loosening of total hip arthroplasties. This has led to renewed interest in the use of metal on metal bearings in hip prostheses. This study employed uniaxial and biaxial multistation pin on plate reciprocators to assess how the carbon content of the cobalt chrome alloy and the types of motion affected the wear performance of the bearing surfaces and the morphology of the wear debris generated.The low carbon specimens demonstrated higher wear factors than both the mixed carbon pairings and the high carbon pairings. The biaxial motion decreased the wear rates of all specimens. Plate wear was significantly reduced by the biaxial motion, compared to pin wear. The metal wear particles isolated were an order of magnitude smaller than polyethylene particles, at 60–90 nm, and consequently, 100-fold more particles were produced per unit volume of wear compared to polyethylene. The low carbon specimens produced significantly larger particles than the other material combinations, although it is thought unlikely that the difference would be biologically significant in vivo.The volumetric wear rates were affected by the carbon content of the cobalt chrome alloy, the material combination used and type of motion applied. However, particle morphology was not affected by the carbon content of the alloy or the type of motion applied. ©©1999©Kluwer Academic Publishers     

柔性光电器件空穴注入层用聚苯胺/纳米ZnO复合材料的制备

弱磁场(0.4 T)下,采用原位聚合方法制备了重均分子量可达3×104的聚苯胺(PANI)及聚苯胺/纳米ZnO复合材料.UV-vis数据表明所制备的纳米ZnO的粒径约为3nm; FT-IR谱图表明纳米ZnO的加入使聚苯胺的特征峰向低波数方向移动;KH550改性纳米ZnO的引入显著地提高了PANI的导电性(220S/m)...     

Oxidation behaviour of ferrous alloys used as interconnecting material in solid oxide fuel cells

Under operating conditions in the solid oxide fuel cell (SOFC), metallic interconnect plates form electrically insulating or poor-conducting oxide scales (e.g. Cr₂O₃, Al₂O₃) at their surface which increase the contact resistance from one fuel cell membrane to the next. In order to minimize electric losses in a fuel cell stack, the formation of oxide scales on the interconnect surface must either be prevented or the oxide scale formed must have sufficient electrical conductivity. In the present work, investigations were carried out on the corrosion behaviour of different FeCrAl and FeCrMn alloys, some of which were coated with nickel (Ni). Information about ageing of these alloys on the anode side of the fuel cell was obtained by means of contact resistance measurements and scanning electron microscopy. The results reveal that FeCrMn(LaTi) alloys and Ni-coated interconnects exhibit low ageing rates and are thus suitable for use on the anode side of SOFCs.     

Using nano-QSAR to predict the cytotoxicity of metal oxide nanoparticles

It is expected that the number and variety of engineered nanoparticles will increase rapidly over the next few years, and there is a need for new methods to quickly test the potential toxicity of these materials. Because experimental evaluation of the safety of chemicals is expensive and time-consuming, computational methods have been found to be efficient alternatives for predicting the potential toxicity and environmental impact of new nanomaterials before mass production. Here, we show that the quantitative structure-activity relationship (QSAR) method commonly used to predict the physicochemical properties of chemical compounds can be applied to predict the toxicity of various metal oxides. Based on experimental testing, we have developed a model to describe the cytotoxicity of 17 different types of metal oxide nanoparticles to bacteria Escherichia coli. The model reliably predicts the toxicity of all considered compounds, and the methodology is expected to provide guidance for the future design of safe nanomaterials.     

Ultrasonic phosphating of Nd-Fe-B magnetic alloys

Ultrasonic phosphating of ground surfaces of Nd-Fe-B magnets was performed at two ultrasound intensities. The process was shown to follow the relationships known for topochemical reactions. High-frequency processing is more efficient in suppressing the autoinhibiting adsorption of reaction intermediates promoted by Schlichting’s acoustic winds in the initial stages of phosphating and has a stronger accelerating effect on intergranular diffusion in the later stages. The low-frequency cavitation results in the erosion of the growing coating. The acceleration of solid-state diffusion prevails over the effect of cavitation heating. The high-frequency phosphating of Nd-Fe-B magnets is more attractive from the viewpoint of the growth rate and corrosion resistance of the resultant coatings.     

Testing the characteristics of magnetic amplifier cores

Conclusion In the design of self-saturating magnetic amplifiers one must abide by the characteristics based on the demagnetization curve B_y=f(H_y) and not by those based on symmetrical magnetization reversal.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 43–45, September 1972.     

Thermoelectric behaviour of amorphous magnetic alloys

The Thermoelectric emfs of thermocouples formed by amorphous METGLAS 2826 (Fe₄₀Ni₄₀P₁₄B₆) and METGLAS 2826B (Fe₂₉Ni₄₉P₁₄B₆Si₂) with standard thermocouple wires like copper, chromel, alumel, etc., were measured as a function of temperature between −196° C and 30° C to assess their suitability as thermoelectric temperature sensors. Thermoelectric emfs generated by METGLAS 2826/Cu and METGLAS 2826B/Cu thermocouples at −196° C are about an order of magnitude smaller when compared to thermal emfs of a standard copper/constantan thermocouple at the same temperature.     

Reduction mechanism of uniform iron oxide nanoparticles to metal used as recording media

Uniform and stable α-Fe nanoparticles of around 40 nm in width and axial ratios from 5 to 7 have been obtained from hematite (α-Fe₂O₃) without any additive. The precursor was synthesized by forced hydrolysis of a Fe(ClO₄)₃ solution in the presence of urea and different amounts of NaH₂PO₄. These particles have been reduced to metal α-Fe by heating under a hydrogen flow and the best conditions of temperature, hydrogen flow and time to preserve the morphology have been established. There is a minimum temperature (400 °C) and a minimum hydrogen flow (20 l/h) to reduce the hematite particles to metal in a reasonable time (4 h), preserving the size and the shape of the particles. The main change in the material is related to the crystallite size of the metal particles, which increases as the reduction proceeds. A detailed analysis of the magnetic properties of these particles during the reduction process and the influence of the particle axial ratio has been carried out.