Synthesis,properties, and gas permeability of novel poly(diarylacetylene) derivatives

Poly(diphenylacetylene)s having various silyl groups are soluble in common solvents, from whose membranes poly(diphenylacetylene) membranes can be obtained by desilylation. The oxygen permeability coefficients of the desilylated polymers are quite different from one another (120–3300 barrers) irrespective of the same polymer structure. When bulkier silyl groups are removed, the oxygen permeability increases to larger extents. Poly[1-aryl-2-p-(trimethylsilyl)phenylacetylene]s are soluble in common solvents, and afford free-standing membranes. These Si-containing polymer membranes are desilylated to give the membranes of poly[1-aryl-2-phenylacetylene]s. Both of the starting and desilylated polymers show very high thermal stability and high gas permeability. 1-Phenyl-2-p-(t-butyldimethylsiloxy)phenylacetylene polymerizes into a high-molecular-weight polymer. This polymer is soluble in common organic solvents to provide a free-standing membrane. Desilylation of this membrane yields a poly(diphenylacetylene) having free hydroxyl groups, which is the first example of a highly polar group-carrying poly(diphenylacetylene). The P/P and P/P permselectivity ratios of poly(1-phenyl-2-p-hydroxylphenylacetylene) membrane are as large as 47.8 and 45.8, respectively, while keeping relatively high P of 110 barrers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5028–5038, 2006     

分布式计算机软件数据整合平台设计

为实现当前经济市场中各应用软件的整合,提高我国各行业间个性化软件的开发能力,加强企业间的科学化系统软件设立,保证企业的高效运行,以及质量和系统维护能力;根据较为常用的分布式计算机系统,提出一种软件数据整合平台的设计;以商用软件整合平台设计为例,以开发模式、服务、技术结构、功能为研究方向,在企业正常运行时,可以实现业务系统功能开发以及门户单点登录,提高企业的个性化系统应用和经济效益;本文根据以上基本需求提出该功能软件平台进行设计,并在实际应用中分析出对于当前企业发展所提供的助力;结果显示,在当前经济发展状况下,有效地使用软件数据整合平台可以很大程度上提高企业的科学化管理和有效的资源分配,使企业在市场竞争中提高经济效益和社会效益。     

A theoretical study on the ionization of OCS with an analysis of vibrational structures of the photoelectron spectrum

 Ab initio calculations have been performed to study the molecular structures and vibrational levels of the four low-lying ionic states (1, 2²Π, and 1, 2²Σ⁺) of carbonyl sulfide. The global regions of the potential-energy surfaces have been obtained by multireference single and double excitation configuration interaction calculations. Vibrational calculations using explicit vibrational Hamiltonians have been used for vibrational analysis. The equilibrium molecular structures and a vibrational analysis of the four ionic states are presented. The theoretical ionization intensity curves including the vibrational structures of the ionic states are also presented and are compared with the photoelectron spectrum. Received: 20 January 2001 / Accepted: 22 August 2001 / Published online: 30 October 2001     

高能γ探测系统中的光耦合部件参数优化

建立了Geant4软件粒子输运模拟平台,完成了核聚变高能射线能量-时间联合谱探测系统的探测效率计算数值建模;提出了遗传算法调用Geant4软件的射线探测系统参数优化方法。以自聚焦透镜前端与塑料闪烁体后端面的距离、自聚焦透镜后端面的长度及自聚焦透镜与通信光纤前端的距离为自变量,以耦合效率为适应度函数,实现了高能探测系统中由塑料闪烁体-自聚焦透镜-通信光纤组成的光耦合部件参数的优化算法。优化结果表明,该算法可以提高塑料闪烁体发出的荧光由自聚焦透镜耦合到通信光纤中的效率,最大可达4.77%。     

Spectrophotometric determination of boron in plants after separation as trimethyl borate by microdiffusion

A sensitive and precise method based on microdiffusion is proposed for the determination of traces of boron in plants. A sealed digestion bomb is used; the powdered sample is dissolved in ZnCl₂/AlCl₃ solution containing methanol in the teflon vessel and the trimethyl borate formed is collected in sodium hydroxide pellets. The boron, as an ion-associate of the 2,6-dihydroxybenzoic acid complex and malachite green, is extracted into chlorobenzene. At 629 nm, Beer's law is obeyed for the range 0.05–0.5 μg of boron. The accuracy of the proposed method was confirmed by analyzing the Orchard Leaves and Pepperbush standards.     

Measurements of interaction cross sections and radii of He isotopes

Secondary beams of ³He, ⁴He, ⁶He, and ⁸He were produced through the projectile fragmentation of an 800 MeV/nucleon ¹¹B primary beam. Interaction cross sections (σ_I) of all He isotopes of 790 MeV/nucleon on Be, C, and Al targets were measured by a transmission-type experiment. The interaction nuclear radii of He isotopes R_I(He) = (σ_I/π)^1/2 − R _I(T) where R_I(T) is the radius of the target nucleus, have been deduced to be R_I(³He) = 1.59 ± 0.06 fm, R_I(⁴He) = 1.40 ± 0.05 fm, R_I(⁶He) = 2.21 ± 0.06 fm, and R_I(⁸He) = 2.52 ± 0.06 fm.     

A snapshot of enzyme catalysis using electrospray ionization mass spectrometry

Insights into the early molecular events involving protein-ligand/substrate interactions such as protein signaling and enzyme catalysis can be obtained by examining these processes on a very short, millisecond time scale. We have used time-resolved electrospray mass spectrometry to delineate the catalytic mechanism of a key enzyme in bacterial lipopolysaccharide biosynthesis, 3-deoxy-d-manno-2-octulosonate-8-phosphate synthase (KDO8PS). Direct real-time monitoring of the catalytic reaction under single enzyme turnover conditions reveals a novel hemiketal phosphate intermediate bound to the enzyme in a noncovalent complex that establishes the reaction pathway. This study illustrates the successful application of mass spectrometry to reveal transient biochemical processes and opens a new time domain that can provide detailed structural information of short-lived protein-ligand complexes.     

Measurement of ultrashort laser pulses using single-crystal films of 4-aminobenzophenone

Single-crystal thin-film of an organic second-order nonlinear optical material, 4-aminobenzophenone (ABP), is used to measure the pulsewidth of a Ti-Sapphire laser producing 45 fs pulses at 1 kHz repetition rate, by the non-collinear second-harmonic generation (SHG) intensity autocorrelation technique. These films are suitable for measurements over a broad wavelength range, down to 780 nm, due to their wide optical transparency. The single-crystal film with thickness (3 μm) less than the coherence length requires no phase-matching for efficient broadband SHG. Pulse walk-off due to group-velocity mismatch (GVM) and temporal broadening of the pulses due to group-velocity dispersion (GVD) are found to be negligible. These effects have been estimated for pulse width down to few-cycle pulses (10 fs), and the analyses show that these films can be used to characterize such ultrashort optical pulses.