微/纳米结构含锌硅酸钙基涂层成骨性能研究

骨科植入物涂层的表面形貌和化学组成对炎症反应的进程和骨形成的发生都发挥着重要调节作用。为综合利用微/纳米仿生结构和生物活性元素的优势,将含锌(Zn)的纳米结构物质引入到经水热处理后的等离子喷涂硅酸钙(calcium silicate, CS)涂层表面,对所制备涂层的物相组成、表面和截面形貌、比表面积、Zeta电位和生理环境下离子溶出等物理化学性能进行了表征。相比于常规CS涂层,具有微/纳米复合结构的CS和含锌CS涂层拥有更高比表面积和孔容,可吸附更多血清蛋白和纤维连接蛋白,通过刺激细胞内整合素以及下游vinculin和FAK基因表达,提高了骨髓间充质干细胞(BMSCs)铺展能力。涂层中锌的引入进一步提高了其表面BMSCs的增殖能力和与成骨细胞分化相关的基因表达。具有微/纳米复合结构的涂层明显上调了RAW264.7巨噬细胞中M2表型因子(CD206和ARG)基因表达,而涂层中溶出的Zn²⁺显著提高了RAW264.7细胞中抑炎症因子(IL-1ra和IL-10)基因表达,促使其向抑炎症表型转化。骨科植入物涂层表面锌元素和纳米结构的引入有利于创建良好的骨免疫微环境,促进骨...     

The Dependence of Energy Dissipation on the Elastic Energy Density of Friction Pairs in Hard Coating Films

The influence of different pairs on the energy dissipation of a given hard coating during fretting has been discussed. Based on the view of the competition between the elastic and plastic deformations in a fretting experiment, it suggests that the energy dissipation rate is proportional to the elastic energy density of pairs. This trend is in agreement with the reported experimental data. For comparison, hardness of pairs is used as the index to relate the antiwear properties of a DLC film against different pairs. It is obvious that the elastic energy density of pairs is more appropriate to predict the antiwear properties of the DLC film against different pairs.     

浅谈机床领域的电磁干扰问题

阐明电磁干扰问题一直是技术人员在机床调试、维修过程中经常遇到的问题.介绍了提高机床电气系统抗干扰的措施以及在实际的机床调试、维修过程中遇到的故障举例及解决方案.     

Centrifuge model tests of geotextile-reinforced soil embankments during an earthquake

The behavior of geotextile-reinforced embankments during an earthquake was investigated using centrifuge model tests, considering a variety of factors such as gradient of slope, water content of soil, geotextile spacing, and input shaking wave. The geotextile-reinforcement mechanism was revealed on the basis of the observations with comparison of the unreinforced embankment. The geotextile significantly decreases the deformation of the embankment and restricts sliding failure that occurs in the unreinforced embankment during an earthquake. The displacement exhibits an evidently irreversible accumulation with a fluctuation during the earthquake which is significantly dependent on the magnitude of input shaking. The peak strain of the geotextile exhibits a nearly triangular distribution in the vertical direction. The embankment can be divided into two zones, a restricting zone and restricted zone, where the soil and geotextile, respectively, play an active restriction role in the soil-geotextile interaction. The soil restricts the geotextile in the restricting zone, and this restriction is transferred to the restricted zone through the geotextile. The strain magnitude of the geotextile and the horizontal displacement of the geotextile-reinforced embankment decrease with increasing geotextile layers, with decreasing water content of the soil, with decreasing gradient of the slope, and with decreasing amplitude of the earthquake wave.     

A GNSS Signal Blind-decoding Algorithm at Low SNR

The pseudo-random noise (PRN) code modulated in satellite navigation signals impacts the system positioning performance directly, and the code monitoring is one of the key technologies. However, the received signal is often buried in noise, and the ranging codes can not visible in time domain. Considering local clock bias, the signal model in transmis-sion link is derived in this paper, and a PRN code blind-decoding method is proposed also. It calculates the signal' s cyclic spectrum by using fast Fourier transform accumulation method (FAM) , and estimates the code rate and Doppler frequency making use of the noise eliminating characteristic in non-zero cycle frequency cross-section. Wiped off the Doppler shift,the navigation message or secondary code bits are determined and removed by slide-correlating a small slice of itself with the whole data. The start of the code is determined by stacking multiple periods of the whole data into a code period, and then the whole data is shifted to the start of the PRN code, and is restacked. Then the individual period of PRN code is esti-mated. An experiment for the proposed algorithm is performed by simulated vector signal analyzer (VSA) collected data.The results indicate that the algorithm is effective and reliable.     

Temperature dependence of ferroelectric and dielectric properties of textured 0.98(0.94Na0.5Bi0.5TiO3–0.06BaTiO3)–0.02K0.5Na0.5NbO3 thick film

Textured 0.98(0.94Na_0.5Bi_0.5TiO₃–0.06BaTiO₃)–0.02K_0.5Na_0.5NbO₃ thick film was prepared by reactive templated grain growth (RTGG) method. The effect of temperature on ferroelectric and dielectric behaviors of the thick film was investigated. Its dielectric constant as a function of temperature displayed typical relaxation behavior, which was similar to that of NBT-based bulk ceramics. Remnant polarization, saturation polarization, and coercive field of the thick film all decreased with increasing temperature. Dielectric constant and tunability of the film were also dependent on temperature. Electric field dependence of dielectric constant of the thick film suggested a transition from ferroelectric to antiferroelectric phase at around the depolarization temperature. A strong increase in leakage current density with increasing temperature was observed, which could be related to the enhanced activity of conductivity carriers.     

多巴胺的自聚-附着行为与膜表面功能化

多巴胺(dopamine)是一种生物神经递质,在水溶液条件下,它能在溶解氧的作用下发生氧化-交联反应,形成强力附着于固体材料表面的聚多巴胺复合薄层.基于多巴胺的这一特性,近年来膜技术研究者们通过多巴胺在固体基膜上的自聚-复合,对膜进行表面改性,并以具有反应活性的聚多巴胺复合层为平台,对膜进行进一步的表面修饰,实现膜的功...     

基于LabVIEW的双燃料发动机测试系统设计与开发

基于NI数据采集卡及调理模块,配合发动机各关键位置的传感器,采用LabVIEW软件编写采集程序和串口通信程序,开发了双燃料发动机实时监控测试系统。利用标准信号发生器等设备校准所开发的测试系统,并在双燃料发动机试验台上获取了部分测试点的实时状态参数,验证了所设计开发的测试系统的精确度。     

酵母创新价值的研究

以食品的安全、美味、营养为对象,阐述了酵母及酵母衍生产品在传统发酵面食、食品铝害、盐与健康以及现代人的营养问题等几个领域的创新价值.