基于改进遗传算法的车间布局重构

以车间设备的多行布局为研究对象,建立以设备序列和间距为决策变量、以最小化车间物流总费用为目标的车间布局重构数学模型.采用遗传算法进行求解,对染色体编码和遗传算子进行了改进.结合某凸轮轴加工车间实例,剖析该车间现有布局存在的问题以及重构的必要性,比较布局重构前后的物流费用,验证了车间布局重构数学模型和改进遗传算法的有效性.     

复方三芪提取物对NMDA致大鼠视网膜损伤的保护作用

目的:研究复方三芪提取物对由N-甲基-D天门冬氨酸(NMDA)诱导的大鼠视网膜损伤模型的保护作用.方法:20只SD大鼠随机分为5组:正常对照组、模型组、复方三芪提取物低、中、高剂量组.模型组和给药组大鼠于右眼玻璃体内注射2μL 40 nmol.L-1NMDA,制备视网膜神经元损伤模型.给药组在NMDA注射前7 d起给予复方三芪提取物灌胃(3.903,7.805,15.61 g.kg-1.B.W.);正常对照组和模型组则给予等剂量的生理盐水灌胃.注射NMDA 7 d后静脉取血,测定血清超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量,取眼球组织,切片HE染色,观察视网膜厚度,并对视网膜视神经节细胞层(RGCL)神经元进行计数.结果:模型组大鼠RGCL神经元个数为正常组大鼠的51±6%.同模型组相比,复方三芪提取物(3.903,7.805,15.61 g.kg-1.B.W.)能剂量依赖性地增加RGCL神经元个数(P<0.05),依次为正常组的69±6%,89±7%,103±7%.复方三芪提取物(7.805 g.kg-1.B.W.)显著提高大鼠血清SOD活性并降低MDA含量(P<0.001).结论:复方三芪提取物能抑制NMDA诱导的视网膜脂质过氧化,并能阻止大鼠视网膜神经元进行性丢失,对NMDA诱导损伤的大鼠视网膜有修复作用.提示复方三芪提取物可能具有促进神经元的再生作用.     

First-principles study of the interactions of hydrogen with low-index surfaces of PdCu ordered alloy

PdCu catalysts play a key role in several hydrogen-involved processes. Among these reactions, the interaction of hydrogen with PdCu essentially determines the catalytic performance. However, the response of PdCu to surrounding hydrogen has been poorly investigated, especially for specific facets of PdCu at different environment. In this work, taking temperature and hydrogen pressure into account, we studied the hydrogen-surface interactions for four low-index surfaces of PdCu through first-principles calculations. It was found that H-PdCu adsorption strong relies on the facets, hydrogen coverage, and reaction environment (temperature and H-pressure). Our work highlights the importance of the environment on the nature of catalyst surfaces and reactions and offers a plausible way to investigate the interactions between gas and the surfaces of nanocatalysts in real reactions.     

大尺寸磷酸盐激光钕玻璃批量制备技术研发及应用

为满足神光装置发展和未来国家专项工程对大尺寸激光玻璃的大量需求,上海光学精密机械研究所研发了以磷酸盐激光钕玻璃连续熔炼技术为核心的大尺寸激光钕玻璃批量制备技术.大尺寸磷酸盐激光钕玻璃批量制备技术是全新的工艺技术,先后攻克了除杂质、动态除羟基、除铂颗粒、小流量大尺寸成型、隧道窑退火过程玻璃易炸裂以及包边和性能检测等一系列关键单元技术,激光玻璃的所有指标包括荧光寿命、光学损耗、光学均匀性、包边剩余反射率等均达到神光装置的使用要求.使中国成为继美国之后第二个拥有大尺寸激光钕玻璃批量制造能力的国家.采用该技术已成功研制了一千多片米级尺寸N31型激光钕玻璃,并且应用于我国的神光系列装置,在中国工程物理研究院实现了1 053 nm激光波长5 ns脉冲宽度单束能量19.6 kJ激光输出.采用本技术研制的激光钕玻璃在国防、强场激光科技前沿、激光加工和医疗领域都得到推广应用.     

Reverse-transformation austenite structure control with micro/nanometer size

To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. The samples were first cold-rolled, and then samples deformed to different extents were annealed at different temperatures. The microstructure evolutions were analyzed by optical microscopy, scanning electron microscopy (SEM), magnetic measurements, and X-ray diffraction (XRD); the mechanical properties are also determined by tensile tests. The results showed that the fraction of stain-induced martensite was approximately 72% in the 90% cold-rolled steel. The micro/nanometric microstructure was obtained after reversion annealing at 820-870℃ for 60 s. Nearly 100% reversed austenite was obtained in samples annealed at 850℃, where grains with a diameter ≤ 500 nm accounted for 30% and those with a diameter >0.5 μm accounted for 70%. The micro/nanometer-grain steel exhibited not only a high strength level (approximately 959 MPa) but also a desirable elongation of approximately 45%.     

Effect of vanadium carbide on commercial pure aluminum

The effect of vanadium carbide (VC) on the grain size of commercial pure aluminum was experimentally investigated by varying the content of VC, the holding time, and casting temperature. The refining efficiencies of VC and Al5Ti1B were also compared. The refined samples of commercial pure aluminum were examined using optical microscopy, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results suggest that VC is a good refiner of commercial pure aluminum. The addition of only 0.3wt% VC can decrease the grain size of aluminum to 102 μm, whereas the casting temperature and holding time have little effect on the grain size. The refining efficiency of VC is better than that of Al5Ti1B. The VC particles in molten aluminum act as nuclei and the grain refinement of aluminum alloys by VC particles is achieved via heterogeneous nucleation.     

Investigation of the deterioration of passive films in H<Subscript>2</Subscript>S-containing solutions

The effect of H₂S on the corrosion behavior of 316L stainless steel was investigated using electrochemical methods by changing the gas condition from CO₂ to H₂S and then back to CO₂. The presence of H₂S showed an acceleration effect on the corrosion of 316L stainless steel in comparison with CO₂. The acceleration effect remained even after the complete removal of H₂S by CO₂, indicating that the passive film was irreversibly damaged. X-ray photoelectron spectroscopy (XPS) analysis indicated that the passive film was composed of Cr₂O₃, Fe₂O₃, and FeS₂ after being immersed in H₂S-containing solutions. The semiconducting property of the passive film was then investigated by using the Mott-Schottky approach. The presence of sulfides resulted in higher acceptor and donor densities and thus was responsible for the deterioration of passive films.     

保护医学——一个正在兴起的交叉学科

保护医学作为一门新兴的交叉学科已受到广泛瞩目。保护医学涉及人类健康、动物健康和生态系统健康3个层面,它们构成有机的整体,相互影响,相互作用,缺一不可。保护医学研究的最终目标是实现生态的健康,这是保证包括人类在内的生命健康的根本前提。它强调健康与生态、环境之间的联系,体现了多学科的交叉,如人类健康和公共卫生、流行病学、兽医学、毒物学、生态学和保护生物学等,而且其研究方法也体现出多学科交叉的特点。     

新型掺铒硼铋锶酸盐玻璃的J-O参数计算

用高温熔融法制备了成分为：B2O3-Bi2O3-SrO的新型掺铒硼铋锶酸盐玻璃．测试了样品的发射光谱和吸收光谱．利用Judd—Ofelt理论计算了该玻璃样品的J-O参数（Ω2,Ω4,Ω6）和Er^3＋各相关能级的理论振子强度、实验振子强度等发光参数,并对其发光特性进行了研究．计算结果表明：该硼铋锶酸盐玻璃的共价性强于已被报道的大多数玻璃,且其跃迁几率最大的两个能级为^4I13/2和^4I15／2能级．     

mRNA detection in living cell using phosphorothioate-modified molecular beacon

In this study, GFP mRNA in COS-7 cell and GFP-transfected COS-7 cell was detected in real time using phosphorothioate-modified molecular beacon based on living cell imaging method. Results showed that phosphorothioate-modified molecular beacon still kept the advantages of molecular beacon, such as, excellent selectivity, high sensitivity, and no separation detection. In addition, this modification could significantly increase the nuclease resistance of molecular beacon. Phosphorothioate-modified molecular beacon can efficiently reduce the false positive signal and improve the accuracy of living cell mRNA detection. Supported by the National Key Basic Research Program (Grant No. 2002CB513110), International Technologies Collaboration Program of China (Grant No. 2003DF000039), and National Natural Science Foundation of China (Grant Nos. 90606003 and 20620120107)