激光等离子体相互作用中超热电子输运过程的蒙特卡罗模拟

利用蒙特卡罗（Ｍｏｎｔｅ－Ｃａｒｌｏ）方法模拟了激光等离子体相互作用中所产生的超热电子在固体物质中的输运过程，模拟运算采用连续慢化（ＣＳＤＡ）和玻恩（Ｂｏｒｎ）近似的单一散射模型。文中给出了具有单能，束状分布的超热电子在双层固体靶中产生的Ｋα射线强度随表面靶层厚度的变化曲线。     

Rapid screening and identification of α-glucosidase inhibitors from mulberry leaves using enzyme-immobilized magnetic beads coupled with HPLC/MS and NMR

α-Glucosidase plays important roles in the digestion and absorption of carbohydrates in the small intestine. The inhibition of α-glucosidase is regarded as a potential way to treat diabetes. We established an approach to screening α-glucosidase inhibitors from medicinal plants using enzyme-coated magnetic bead. Using 1-(3-dimethyl-aminopropyl)-3-ethylcarbodiimide and N-hydroxysuccinimide as reaction reagents, α-glucosidase was immobilized on the magnetic beads by covalent linkage. The conjugation of α-glucosidase to the magnetic beads was characterized using scanning electron microscope and X-ray diffractometer. The proposed approach was applied in fishing potential α-glucosidase inhibitors from extract of Morus alba, a Chinese medicinal plant. The structures of potential active compounds were identified via liquid chromatography-mass spectrometry and nuclear magnetic resonance. The results demonstrated that two flavonoids (isoquercitrin and astragalin) could bind to α-glucosidase, which was confirmed via conventional α-glucosidase inhibitory assay. Our findings suggested that enzyme-coated magnetic beads may be suitable for discovering active compounds from medicinal plants.     

N-Phospho-α-Amino Acids and Co-Evolution of Nucleic Acid and Protein

N-phospho-α -amino acids obtainable from aqueous condition were different from their corresponding β -analogues intrinsically. As the self-reproduction unites, N-phospho-α -amino acids were capable to produce non-random oligopeptides. As the phosphoryl donor, they were able to phosphorylate the nucleosides much faster than the deoxynucleosides.     

4.2 GeV α-^12C Elastic Scattering Based on α-Particle Model

Based on the α-particle model of ^12C nucleus, the differential cross sections for α-^12C elastic scattering at incident energy of 4.2 GeV have been calculated within the framework of Glauber multiple scattering theory. The results show that the main features of the measured angular distribution of the cross sections can be reasonably described. The parameterized α-α scattering amplitude, which is the basic input to construct the α-^12 C scattering Glauber amplitude in the a-particle model, is obtained by fitting the α-α scattering data.     

电子碰撞Ga,As, Pt,W和Au原子Lα X射线产生截面的理论计算

利用修改后的MBELL模型,研究了L壳层的相对论效应和离子效应对快电子碰撞电离Lα X射线产生截面的影响.通过在BELL模型中引入相对论效应和离子效应,基于相对论性的L壳层的电子碰撞电离截面的理论,计算了Ga,As,Pt,W和Au的L壳层电子碰撞电离截面,并将其转化成Lα X射线产生截面,计算结果表明考虑到相对论效应和离子效应后,修改后的MBELL的Lα X射线产生截面结果明显优于BELL的计算结果,并和最近的文献实验数值 关键词： 快电子 Lα射线')" href="#">Lα射线 电离截面 相对论效应     

On the stability and transition for the Navier-Stokes-alpha model

The main aim of this paper is to investigate the stability and transition of the Navier-Stokes-alpha model. By using the continued-fraction method, combining with the dynamic transition theory, we show the existence of a Hopf bifurcation in this model as Reynolds number crosses a critical value. Upon deriving the explicit expression of a non-dimensional number P called transition number, which is a function of the critical Reynolds number and the aspect ratio, we further analyze the transition associated with the Hopf bifurcation. More precisely, it is shown that the modeled flow exhibits either a continuous or catastrophic transition at the critical Reynolds number, whose specific type of the transition is determined by the sign of the real part of P at the critical Reynolds number, and the spatio-temporal structure of the limit cycle bifurcated that corresponds to a wave that propagates slowly westward and is symmetric about the mid-axis of the channel.     

超短超强激光与铜靶相互作用产生Kα源的蒙特卡罗模拟

超短超强激光打靶产生的超热电子，与固体靶相互作用时会产生Kα线辐射.由经典定标律给出了法线方向超热电子的温度.利用蒙特卡罗方法，对超热电子在固体靶中的传输进行了研究，模拟了不同靶厚度情况下Kα产额和角分布及不同电子温度下Kα光子的转化效率.计算结果与实验符合较好.结果表明：在一定电子温度下，随着靶厚度的增加Kα光子产额会达到饱和，并会使Kα光子发射的各向异性变得更加严重；存在最佳的电子温度，使Kα线转化效率最高. 关键词： 超短超强激光 超热电子 蒙特卡罗方法 Kα线')" href="#">Kα线     

基于改进NSGA-II算法的云制造服务组合优化研究

云制造任务日趋复杂,与基于云制造的云服务组合优化问题相关的指标日益增多,需要综合考虑各个评价指标,从海量备选云服务中筛选出最优服务组合。本文针对云制造的特点,从线上、线下两方面构建了云制造服务评价指标体系;为了更好地处理高维多目标优化问题并消除实际问题中的量纲影响,本文利用改进的α支配策略代替帕累托支配改进NSGA-II算法,提出了基于nα支配的NSGA-II算法。最后,本文通过一个电机制造案例验证了提出算法的可行性,并通过与标准NSGA-II算法、r-NSGA-II算法和基于模糊支配的NSGA-II算法对比,证明了提出算法得到的解集更优、更小,能够大大减小后续组合优选的计算量。     

Anti-inflammatory flavanol glycosides from Saraca asoca bark

Saraca asoca (Roxb.) de Wilde, a common tree of India, is popularly used in the Ayurvedic and modern herbal systems of medicine for genito-urinary problems of women. Considering the reported antimicrobial or anti-inflammatory effect of S. asoca bark against such infections, we studied the anti-inflammatory activity-guided isolation of active compounds from methanol extract. The methanol extract of bark has yielded 10 compounds out of which 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6) and 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) have been found to be in vitro and in vivo active. 3′,5-Dimethoxy epicatechin (3), 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6), 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) and epigallocatechin (9) are being reported for the first time from S. asoca.