制造企业基于Internet的设备远程诊断与维护系统研究

介绍了一个用于汽车发动机自动生产线的远程监控与诊断系统的结构与功能,对系统实现的有关关键技术进行了探讨,并给出了运行实例。     

EasyDisc法与传统平皿计数法检测水中菌落总数的比较

采用EasyDisc法与平皿计数法对水中菌落总数进行检测。通过检测质控样品及质控稀释样品,计算其检测结果与真值的相对误差及相对误差的标准偏差,结果表明：EasyDisc法相对误差更小,更接近于真值,结果更为准确;两种方法相对误差的标准偏差为SD(平皿计数法)=5.84%,SD(EasyDisc法)=3.66%,EasyDisc法与真值相对误差的标准偏差更小,其连续检测的稳定性优于平皿计数法;通过检测管网水和二次供水,并对两种方法检测结果进行统计学分析,发现两种方法具有相关性,且在统计学上无显著性差异。与平皿计数法相比,EasyDisc法测定水中菌落总数具有准确度高、稳定性好、操作简便等优势,满足了实验室对水中菌落总数的检测要求。     

Effect of selective laser melting on microstructure and properties of AZ91D alloy

Selective laser melting technology is used to manufacture porous and solid AZ91D alloys. The effects of laser power and hatch spacing on the density, blowholes, microstructure and mechanical properties of AZ91D alloy are studied. The laser power and hatch spacing play a significant role in the density and blowholes of AZ91D specimens. The grains size of specimens increases from 1 μm–2 μm to 8 μm–10 μm from the bottom to the top in single molten pool. Compared with grain size of die‐casting alloy (30 μm), that of selective laser melted gets refinement. There is no significant change in microstructure in the bottom, middle and top of specimens. The micro‐hardness of AZ91D alloy, reaching up to 115.3 HV 0.1, is superior to that of die‐casting alloy (56 HV 0.1). The compression properties of porous and solid specimens reach the degree of die‐casting solid magnesium alloy. AZ91D alloy shows the potential in the application of medical biodegradable materials.     

氦原子间的范德瓦尔斯力与其半经验势函数的拼接构造

为了确定氦原子势函数的具体形式,通过分析氦原子间的范德瓦尔斯作用力,指出氦原子势函数可由其范德瓦尔斯排斥势和吸引势拼接构造而成,并得出了氦原子通用势函数的具体形式.结果表明:对于氦原子势函数,排斥力不再适宜采用原子中心间距r的-12次方的形式,而更适合采用指数形式的排斥项,因此其势函数通用形式中包括指数型排斥项以及分别...     

Ultrasensitive aptamer-based multiplexed electrochemical detection by coupling distinguishable signal tags with catalytic recycling of DNase I

This work reports an aptamer-based, disposable, and multiplexed sensing platform for simultaneous electrochemical determination of small molecules, employing adenosine triphosphate (ATP) and cocaine as the model target analytes. The multiplexed sensing strategy is based on target-induced release of distinguishable redox tag-conjugated aptamers from a magnetic graphene platform. The electronic signal of the aptasensors could be further amplified by coupling DNase I with catalytic recycling of self-produced reactants. The assay was based on the change in the current at the various peak potentials in the presence of the corresponding signal tags. Experimental results revealed that the multiplexed electrochemical aptasensor enabled the simultaneous monitoring of ATP and cocaine in a single run with wide working ranges and low detection limits (LODs: 0.1 pM for ATP and 1.5 pM for cocaine). This concept offers promise for rapid, simple, and cost-effective analysis of biological samples.     

Large-scale fabrication of bioinspired fibers for directional water collection

Spider-silk inspired functional fibers with periodic spindle-knots and the ability to collect water in a directional manner are fabricated on a large scale using a fluid coating method. The fabrication process is investigated in detail, considering factors like the fiber-drawing velocity, solution viscosity, and surface tension. These bioinspired fibers are inexpensive and durable, which makes it possible to collect water from fog in a similar manner to a spider's web.     

Effect of V doping concentration on the electronic structure,optical and photocatalytic properties of nano-sized V-doped anatase TiO2

V-doped TiO₂ with V/Ti ratio of 1–5% has been synthesized by hydrothermal method and then characterized by XRD, TEM, BET specific surface area, XPS and UV–vis. absorption spectra. The photocatalytic activity of the as-synthesized samples was investigated by the degradation of methylene blue in aqueous solution under visible light irradiation. Density functional theory (DFT) based calculations were performed to investigate the mechanism of band gap narrowing, the shift of light absorption edge, the location of V in the TiO₂ lattice and the variation in electronic and optical properties of TiO₂ with the increase of V doping concentration. Irrespective of the V doping concentration, TEM images indicate that all the doped samples were composed of equiaxed spherical anatase TiO₂ particles with good crystallinity and uniform particle size distribution. Both the experimental results from XPS survey and the theoretical calculation argue that the doped V replaces the lattice Ti and form substitutional impurity. The visible light absorption can be optimized by adjusting the V doping concentration. Among the doped samples with different V doping concentrations, the sample with V/Ti ratio of 2% depicts better visible light photocatalytic activity due to the enhanced visible light absorption and improved separation of electron–hole pairs.     

复合二氧化钛膜的研制

用溶胶 -凝胶法在多孔α -Al2 O3陶瓷衬底上制备了TiO2 微孔膜 ,经激光光散射仪、X -射线衍射仪、扫描电子显微镜、孔率计等对胶粒的大小、膜的结构、形貌和孔径分布等进行了表征 ,发现在孔直径为 0 .5μm的多孔载体上经浸渍 -干燥 -焙烧过程 ,能制得对牛血清白蛋白 (BSA)有 73.5%～ 92 .7%截留率、通量在 0 .2MPa压差下约 52L/(m2 ·h)的超滤膜 .