产生短间隔高精度纳秒激光双脉冲的实用电路

本文介绍了我们研制的“运动粒子瞬态激光全息测试仪”电子线路.该电路经严格的逻辑设计及计算,采用了10MHz时钟电路,并将1MHz的时钟信号巧妙地引入门控电路中,同时在技术上采用了行之有效的措施,消除了可能产生0.1μs的随机误差,时间间隔达到了(1～9)±0.1μs的精度,所输出的激光双脉冲能量接近,整机抗干抗能力强,一次性试验成功率高,可精确地测量雾化粒子场中的微粒的速度、形状、大小及其分布,收到了良好的使用效果.     

乙醇酸和DL─乳酸交替共聚物的合成和表征

乙醇酸和ＤＬ－乳酸交替共聚物具有不同于其无规共聚物的理化性能和生物降解性。以ＤＬ－３－甲基－１，４－二烷－２，５－二酮为单体，通过在辛酸亚锡引发下的本体开环聚合，合成了该交替共聚物，并进行了结构表征。     

超声波作用下羰基化合物的还原偶联反应

超声波在一些有机反应中有明显的促进作用「“，Luche等认为超声波的作用有两种主要类型［’j．一类是涉及电子转移的自由基或离子一自由基型反应，由于超声波的空化作用所产生的局部高温高压可以促进电子转移，从而明显地加快反应速度；对大多数离子型反应，超声波只能起到机械的物理作用．我们曾报道偕二卤化合物在Li、Na、Mg等金属作用下产生卡宾的反应是单电子转移过程，该反应可由于超声辐射而大大加速［‘］；而在芳基叔脚的断裂反应中，超声波可以促进三苯基俄与金属馊反应生成二苯基脚负离子，但对它进一步的亲核取代反应却没有明…     

丙烯环氧化反应的高活性钼催化剂

在钼(Ⅵ),钒(Ⅴ)和钛(Ⅳ)等化合物存在下,丙烯与烷基过氧化氢的环氧化反应比传统的氯醇法有很多优点,其中以钼催化剂的性能最优,但目前报道的催化剂在反应过程中因易分解而降低了活性,并且丙烯与烷基过氧化氢的投料比过大(>3:1),丙烯循环次数过多。前文报道了钼烷基醇胺化合物对环已烯的环氧化反应,本文考察了钼烷基醇胺化合物对丙烯与叔丁基过氧化氢环氧化反应的催化性能。     

Qualitative analysis for a mathematical model of aids

In this paper a mathematical model of AIDS is investigated. The conditions of the existence of equilibria and local stability of equilibria are given. The existences of transcritical bifurcation and Hopf bifurcation are also considered, in particular, the conditions for the existence of Hopf bifurcation can be given in terms of the coefficients of the characteristic equation. The method extends the application of the Hopf bifurcation theorem to higher differential equations which occur in biological models, chemical models, and epidemiological models etc.This project is supported by the National Science Foundation Tian Yuan Terms and LNM Institute of Mechanics Academy of Science.This project is supported by the National and Yunnan Province Natural Science Foundation of China.     

Templateless assembly of molecularly aligned conductive polymer nanowires: a new approach for oriented nanostructures

Although oriented carbon nanotubes, oriented nanowires of metals, semiconductors and oxides have attracted wide attention, there have been few reports on oriented polymer nanostructures such as nanowires. In this paper we report the assembly of large arrays of oriented nanowires containing molecularly aligned conducting polymers (polyaniline) without using a porous membrane template to support the polymer. The uniform oriented nanowires were prepared through controlled nucleation and growth during a stepwise electrochemical deposition process in which a large number of nuclei were first deposited on the substrate using a large current density. After the initial nucleation, the current density was reduced stepwise in order to grow the oriented nanowires from the nucleation sites created in the first step. The usefulness of these new polymer structures is demonstrated with a chemical sensor device for H(2)O(2), the detection of which is widely investigated for biosensors. Finally, we demonstrated that controlled nucleation and growth is a general approach and has potential for growing oriented nanostructures of other materials.     

超宽带减反射膜的设计和制备

设计了400～900 nm波段上的超宽带减反射膜,在410～850 nm范围内的平均残余反射率设计值约为0.2%,在设计的全波段上约为0.24%.讨论了初始膜系结构的选择原则,分析了带宽、膜层折射率差、最外层折射率和膜层总厚度等因素对宽带减反射特性的影响.对特定的带宽.增加两种薄膜材料的折射率差和选择尽可能低的最外层折射率对获得优良的减反射特性是非常重要的.实验制备了K9玻璃上TiO2/MgF2两种材料组成的8层结构的超宽带减反射膜,实测结果表明,在带宽520 nm范围内的平均残余反射率约为0.44%,说明用二种材料设计超宽带减反射膜是成功的,对垂直入射的减反射膜.多种材料的膜系并不比两种材料更具优越性.     

Enantiomeric separation of 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs by HPLC with hydroxypropyl‐β‐cyclodextrin as chiral mobile phase additive

The enantio‐separations of eight 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs (2‐APA NSAIDs) were established using reversed‐phase high‐performance liquid chromatography with hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP‐β‐CD and column temperature on retention and enantioselective separation were investigated. With 2‐APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP‐β‐CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC‐ODS (150 × 4.6 mm i.d., 5 μm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0–5.5, 20 mM) containing 25 mM HP‐β‐CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2‐APA NSAIDs in an enantioselective skin permeation study. Copyright © 2009 John Wiley & Sons, Ltd.     

Tuning of Ti-doped mesoporous silica for highly efficient enrichment of phosphopeptides in human placenta mitochondria

Extraction of phosphopeptides from rather complex biological samples has been a tough issue for deep and comprehensive investigation into phosphoproteomes. In this paper, we present a series of Ti-doped mesoporous silica (Ti-MPS) materials with tunable composition and controllable morphology for highly efficient enrichment of phosphopeptides. By altering the molar ratio of silicon to titanium (Si/Ti) in the precursor, the external morphology, Ti content, internal long-rang order, and surface area of Ti-MPS were all modulated accordingly with certain regularity. Tryptic digests of standard phosphoprotein α- and β-casein were employed to assess the phosphopeptide enrichment capability of Ti-MPS series. At the Si/Ti molar ratio of 8:1, the optimum enrichment performance with admirable sensitivity and capacity was achieved. The detection limit for β-casein could reach 10 fmol, and 15 phosphopeptides from the digest of α-casein were resolved in the spectrum after enrichment, both superior to the behavior of commercial TiO₂ materials. More significantly, for the digest of human placenta mitochondria, 396 phosphopeptides and 298 phosphoproteins were definitely detected and identified after enrichment with optimized Ti-MPS material, demonstrating its remarkable applicability for untouched phosphoproteomes. In addition, this research also opened up a universal pathway to construct a composition-tunable functional material in pursuit of the maximum performance in applications.