晶须概念的泛化与学术影响

最初只称单晶短纤维为晶须,稍后结晶较好的多晶纤维也被称为"晶须",现在无定形纤维也归进了晶须专著,通过对晶须概念泛化过程的反思,希能澄清学术著作中10多年来相沿的一个模糊认知。     

PAMAM体型缩聚物的制备及其性能研究

以分子末端带有多官能度活泼端基的PAMAM等为原料 ,通过缩聚反应制备了一类新型体型缩聚物 .借助X射线光电子能谱仪 (XPS)对制备的体型缩聚物进行分析 ,利用其化学分析电子光谱 (ESCA)中碳元素价态的拟合数据判断体型缩聚反应进行的程度 ,数据表明酯基碳 (—COO)拟合峰已基本消失 ,说明其与氨基缩合反应转化为酰胺基 (—CON) ,且反应进行的比较彻底 .通过体型缩聚物在乙醇、正己烷、甲苯、氯仿、异丙醇、乙酸、甲酸、去离子水中进行溶胀试验 ,发现其在甲酸作为溶剂体系中的溶胀比出现最大值 ,根据溶度参数的意义估测体型缩聚物的溶度参数约为δ2 =2 7 6 (MJ m3) 1 2 (即甲酸的溶度参数 ) .对原料PAMAM以及制备的体型缩聚物进行DSC分析 ,发现制备体型缩聚物的玻璃化转变温度 (Tg)有了较大提高 ,从初始原料PAMAM的负值提高到 4 8℃左右 .     

含氢碳原子团簇的初步研究

介绍直接用激光溅射芳香化合物固态样品产生的含氢磷原子团簇离子（C_nH~＋_m），并用飞行时间质谱仪研究了其组成和结构．实验发现，在低质量区（n＝32－56）得到了具有奇偶碳原子数的含氢磷原子簇，而在高质量区（n＞100）除了得到纯碳原子簇以外，还得到了含氢碳原子簇．根据对实验结果的分析提出了两种结构模型：对低质量区的团簇，其结构为芳香基团与富勒烯笼状框架的复合体；对高质量区的团簇，其结构为蜗牛形与圆柱形的复合体．     

光纤松耦合型传感器特性研究

本文介绍一种实用的光纤传感器,它由二根光纤或多根光纤紧靠一起,并在同一位置除去局部包层,成为松耦合状态,在这种状态下,研究了它的特性和应用。 当耦合间隙中充满某种液体介质时,耦合效率明显增大,因此可以方便地判别该介质是否存在。并且实验证明了一种光纤只能有一种相近于光纤芯子折射率的介质具有最大的灵敏度。当间隙内的介质不变时,耦合功率的大小决定于耦合距离d和耦合长度l,l一旦决定以后,d的调节精度为0.1mm量级,易于在机械结构上实现线性检测。     

Synchrotron X-ray structures of cellulose I<Subscript>β</Subscript> and regenerated cellulose II at ambient temperature and 100 K

Synchrotron X-ray data have been collected to 1.4 Å resolution at the NE-CAT beam-line at the Advanced Photon Source from fibers of cellulose I_β and regenerated cellulose II (Fortisan) at ambient temperature and at 100 K in order to understand the effects of low temperature on cellulose more thoroughly. Crystal structures have been determined at each temperature. The unit cell of regenerated cellulose II contracted, with decreasing temperature, by 0.25%, 0.22% and 0.1% along the a, b, and c axes, respectively, whereas that of cellulose I_β contracted only in the direction of the a axis, by 0.9%. The value of 4.6×10^?5 K^?1 for the thermal expansion coefficient of cellulose I_β in the a axis direction can be explained by simple harmonic molecular oscillations and the lack of hydrogen-bonding in this direction. The molecular conformations of each allomorph are essential unchanged by cooling to 100 K. The room temperature crystal structure of regenerated cellulose II is essentially identical to the crystal structure of mercerized cellulose II.     

钽硫原子簇的形成及激光裂解的初步研究

报导用激光直接溅射的方法产生了大量的钽硫原子团簇离子Ta_nS_m~+(n≤9, m≤30),并用串级飞行时间质谱仪研究了所产生团簇离子的组成及紫外激光裂解规律。实验发现, 最稳定的团簇正离子往往具有Ta_nS_(2n+7)~+(n=1,2,…9)的组成, 相应的负离子具有, Ta_nS_(2n+3)~-(n=1,2,…9)的组成。各种团簇正离子的激光裂解的主要通道是连续的S_2消除过程, 且对于n=3,4,5的团簇, 主要光解产物还有Ta_3S_4~+或Ta_4S_6~+离子。据此推测出Ta_nS_m~+团簇离子的可能结构为在Ta原子周围有6个左右的S原子配位。Ta原子之间不存在直接的化学键,而较大团簇可能是以Ta_3S_4或Ta_4S_6为核心的结构。     

亚硝酸甲酯分子在440nm附近的激光光解

近年来亚硝酸甲酯分子（CHa0NO）的光解动力学研究十分活跃｛‘5］，主要集中在紫外激光的单光子解离的机理，光解过程的矢量相关性质和光解产物的态分布．CH30NO分子的解离能D。（CH30－NO）＝174kJ·mol‘，若单从能量上看，人＜689。的光就能使其解离，但人＞400urn的光解离研究还未见报导．＊H30＊0分子在人＞40onm的强激光场下是充电离还是先解离，是单光子解离还是多光子解离，以及通过哪个电子态解离都不清楚．时间飞行质谱不仅具有质量分辨率高、范围宽，而且响应快，因此适合做光解光电离过程初生态产物的探测．特别是时间飞…     

Designing a plano-convex aspheric lens for fiber optics collimator

A plano-convex aspheric lens is designed to collimate the emitted light of the fiber optics. In this paper even orders of general aspheres are used to describe the aspheric surfaces sag. To determine the aspheric coefficient, the even asphere polynomial are fitted on the computed sag data. The surface sag data is determined using genetic algorithm method. The surface sag was analyzed by the commercial optical software package ZEMAX. For typical fiber optics, the numerical aperture (NA) of 0.22 was assumed. With this specification, the expected output spot diagram of 20 mm and the maximum aperture of 25.4 mm have been obtained. A comparison between here presented lens and the similar type of conventional lens has been carried out; the proposed aspheric lens corrected the spherical aberration, which led to increase in the collimated distance.     

In vitro metabolism study of Strychnos alkaloids using high‐performance liquid chromatography combined with hybrid ion trap/time‐of‐flight mass spectrometry

In this report, the in vitro metabolism of Strychnos alkaloids was investigated using liquid chromatography/high‐resolution mass spectrometry for the first time. Strychnine and brucine were selected as model compounds to determine the universal biotransformations of the Strychnos alkaloids in rat liver microsomes. The incubation mixtures were separated by a bidentate‐C₁₈ column, and then analyzed by on‐line ion trap/time‐of‐flight mass spectrometry. With the assistance of mass defect filtering technique, full‐scan accurate mass datasets were processed for the discovery of the related metabolites. The structural elucidations of these metabolites were achieved by comparing the changes in accurate molecular masses, calculating chemical component using Formula Predictor software and defining sites of biotransformation based upon accurate MSⁿ spectral information. As a result, 31 metabolites were identified, of which 26 metabolites were reported for the first time. These biotransformations included hydroxylation, N‐oxidation, epoxidation, methylation, dehydrogenation, de‐methoxylation, O‐demethylation, as well as hydrolysis reactions. Copyright © 2013 John Wiley & Sons, Ltd.     

Nonlinear optical metal-organic frameworks for ratiometric temperature sensing in physiological range

The precise and real-time sensing of the temperature within the physiological range is of great significance in biology and medicine. Here, a Zn-based metal-organic framework (MOF) named Zn-TCOMA is synthesized with good SHG performance due to its unique structure of the ligand and 3D frameworks. By encapsulating the two-photon fluorescent dye DMASE into the pores of Zn-TCOMA, the composite Zn-TCOMA?DMASE is obtained and simultaneously exhibits SHG response and two-photon fluorescence. Utilizing the intensity ratio between two-photon fluorescence of DMASE and SHG signal of Zn-TCOMA, Zn-TCOMA?DMASE exhibits ratiometric temperature sensing property at physiological temperature region of 20～60 °C with high sensitivity. This MOF thermometer also shows excellent repeatability, good biocompatibility, and high temperature resolution of 0.018 °C, opening a new avenue to develop diverse optical thermometric or thermographic applications in biotechnology or other areas.