Self-assembly behaviour of amphiphilic diblock copolymer in selective solvents studied by synchrotron small-angle x-ray scattering

The aggregation behaviour of styrene-vinyl benzoic acid (PSm-b-PVBAn) amphiphilic diblock copolymers in selective solvents with different m and n was investigated by synchrotron small-angle x-ray scattering (SAXS). We have carried out a detailed analysis of scattering intensity, dimension, shape and microstructure of the diblock copolymers of narrow distribution in water, methanol, ethanol and isopropanol selective solvents, respectively. We have found that the aggregation behaviour of the copolymer depends on the nature of the solvent and the micelle forms fiat disc objects with the ratio of radius ω=0.4. The average radius gyration Rg of the copolymer decreases as solvents change from isopropanol to ethanol and to methanol, and increases with increasing pH in aqueous solution, but decreases with the addition of COCl2 in ethanol solvent. The scattering intensity of diblock copolymer micelle follows I(h) ∝ h^-α in different selective solutions, suggesting that the PSm-b-PVBAn coils have self-similar structure behaviour or a fractal structure in the selective solvents. All of these revealed that the aggregation behaviour of the diblock copolymer changes dramatically with experimental condition in the selective solvent. The increase of mass fractal dimension (Dm) from 2.12 to 2.47 indicates that the copolymer chain changes from a swollen coil to a rather compact disc in the course of changing solvents, decreasing surface fractal dimension (Ds) from 2.98 to 2.58 indicates that the copolymer micelle change from a rather rough surface to a smooth form in the course of increasing pH in aqueous solutions, and increasing Dm and Ds from 2.29 to 2.35 and 2.70 to 2.90, respectively, indicates the shrinkage of copolymer micelle to a rather compact and rough disc form by adding COCl2 in ethanol solvents.     

关于气体中有无速率为无穷大分子的再讨论

本文以较简捷的方法讨论了气体分子速率问题，给出了计算分子最大速率的理论公式，通过这些讨论可更加深入地理解气体中分子的运动情况，准确地理解麦克斯韦速率分布函数。     

斐索梯度折射率光纤透镜传感实验

采用LD泵浦的单纵模Nd：YVO4倍频激光器、梯度折射率光纤透镜等器件构成斐索梯度折射率光纤透镜传感实验仪．本文介绍了实验装置和实验原理，并给出了实验结果。     

Silane photoabsorption spectra mear the Si 2p thresholds：the geometry of Si 2p excited SiH4

Based on the multiple-scattering self-consistent-field method, we have studied the photoabsorption spectra near the Si 2p thresholds of silane. According to our calculations, the clear assignments of the inner-shell photoabsorption spectra are provided. In comparison with the high-resolution experimental spectra, the geometric structure of the Si 2p-excited SiH_{4}^{**} is recommended to be of a C_{2v} symmetry. More specifically, the Si 2p-excited SiH_{4}^{**} have two bond lengths of 2.50 a.u. and another two bond lengths of 2.77 a.u., and the corresponding two bond angles are 104.0° and 112.5° respectively.     

Simultaneous Measurement of Transverse Load and Temperature Using a single Long—Period Fibre Grating Element

A single long-period fibre grating (LPFG)element written by focused high-fraequency CO2 laser pulses is demonstrated for simultaneous measurement of transverse load and temperature.Temperature and transverse load can be directly measured by detecting the resonant wavelength shift and the resonant peak amplitude change of the LPFG,respectively,as there are two special circular orientations along the fibre axis where the resonant peak amplitude change of the LPFG has a linear relationship with the load applied and is insensitive to the resonant wavelength shift.Such a sensor could solve the cross-sensitivity problem between transverse load and temperature due to the unique feature of this type of LPFG,i.e. the wavelength-load-sensitivity of the LPFG strongly depends on loading orientations due to the non-uniform distribution of the refractive index on the cross-section of the LPFG caused by the thermal shock effect and other effects of the high-frequency CO2 laser pulses exposure method used.     

一种光纤位移传感器中的参考光纤

本文介绍了一种强度反射式光纤位移传感器，其探头是由几根排列后的光纤构成，其中的一根光纤作为参考光纤。主要分析了参考光纤在该传感器中的独特作用，既提高传感器的稳定性和抗干扰能力，又改善输出信号的线性和增大量程范围。     

烷烃类分子对NC0（A^2∑^＋）自由基的猝灭

采用激光光解—激光诱导荧光(LP—LIF)的方法，用266nm激光光解CHBr3分子产生CH自由基，再与N2O继续反应作为NCO自由基的产生源，用438．6nm激光将电子基态X^2∏i(00^10)的NCO激励到激发态A^2∑^+(00^00)上，通过检测激发态NCO时间分辨荧光信号，测得室温(298K)下NCO(A^2∑^+)被烷烃类分子猝灭的实验结果，获得了A^2∑^+(00^00)态猝灭速率常数．实验发现，随着烷烃分子中C—H键数增加，其猝灭截面也近线性增加，但随着分子体积增大，这种增加趋缓．     

碰壁分子的平均速率和平均能量

本文对气体系统内的碰壁分子的平均速率和平均能量为会么会大于系统内分子的平均速率和平均能量进行了定性解释，并求出了这两类不同平均值之间的一般关系，最后针对经典理想气体算出了定量结构。     

基于单光纤对模型的光纤束调制函数的建模与仿真

基于单光纤对光强调制特性的函数表达式,建立了双束型光纤束的调制函数,并引入一个虚拟轴间距参量,建立了随机型光纤束的光强调制函数.同时又在视内圈光纤束为单根粗光纤的情况下,建立了同轴I型和同轴型光纤束的光调制函数.在随机型和同轴型光纤束模型的基础上建立了双圈型(DC)和同轴随机型(C-R)光纤束的光调制系数.最后对上述光纤束的调制特性函数进行了计算机仿真实验.     

绝缘表面和气体导电与湿度的关系

湿度对绝缘体表面电导和气体电导有一定的影响，但通常在湿度传感器的研究中忽略了气体电导的贡献。本文通过特殊设计装置来区分表面电导和气体电导，并分别从实验和理论上进行了定性的研究。