聚合物 分散液晶体系的相分离结构对温度依赖性的研究

在不同温度下采用紫外光引发相分离法制备了聚合物分散液晶样品．用光学显微镜及扫描电镜研究了样品的相分离结构．采用对样品施加电压观察其微结构轮廓，或测量液晶微粒相变点的简单方法研究了聚合温度对相分离结果的影响．结果表明，在一定温度范围内，随着温度的增高，液晶微粒的平均尺寸趋于减小，而且形成的液晶微粒也逐渐变纯．作者给出了这些测试结果并进行了讨论．     

三维荧光二阶校正法用于复杂基体样中川芎嗪和替米沙坦的快速定量分析

采用三维荧光光谱法,结合化学计量学中基于交替归一加权残差(ANWE)算法的二阶校正方法,实现了人血浆样品中川芎嗪和替米沙坦的同时快速定量分析.当组分数N取4时,ANWE算法解析获得的川芎嗪和替米沙坦的平均回收率分别为99.3士3.5%和96.8±2.0%.本文同时给出了此方法的检测限(LOD)与定量下限(LOQ),获得...     

The pressure induced B1-B2 phase transition of alkaline halides and alkaline earth chalcogenides. A first principles investigation

In this work, we considered the pressure induced B1-B2 phase transition of AB compounds. The DFT calculations were carried out for 11 alkaline halides, 11 alkaline earth chalcogenides and the lanthanide pnictide CeP. For both the B1 and the B2 structures of each compound, the energy was calculated as a function of the cell volume. The transition pressure, the bulk moduli and their pressure derivatives were obtained from the corresponding equations of state. The transition path of the Buerger mechanism was described using roots of the transition matrix. We correlated the computed enthalpies of activation to some structure defining properties of the compounds. A fair correlation to Pearsons hardness of the ions was observed.     

三维荧光二阶校正同时测定人体液中伊立替康及其代谢物7-乙基-10-羟基喜树碱的含量

提出了激发发射矩阵荧光光谱与化学计量学二阶校正方法相结合用于同时快速定量人体液(血浆和尿液)中的伊立替康(CPT11)和其主要代谢产物7-乙基-10-羟基喜树碱(SN38)的绿色、高灵敏分析策略. 尽管其分析物之间以及分析物和背景之间的光谱存在严重重叠现象, 采用基于交替归一加权残差(ANWE)算法的二阶校正方法进行解析仍能得到令人满意的定性定量分析结果. 当该体系的组分数选取为3时, 可以得到血浆和尿液中CPT11的平均回收率分别为(96.8±6.3)%和(101.7±1.1)%, SN38在血浆和尿液中的平均回收率分别为(100.4±4.9)%和(101.6±1.1)%. 另外, 通过品质因子, 如灵敏度(SEN)、选择性(SEL)、检测下限(LOD)和定量检测限(LOQ)评估了该方法的准确性. 实验结果表明, 该方法能以“数学分离”代替繁琐的“物理和化学分离”, 成功地解决实际复杂体系中内源干扰物质与分析物光谱重叠所引起的难分辨的问题, 可用于人体液中CPT11和SN38含量的直接快速定量测定.     

Phase separation and disorder in half metallic ferromagnetic manganite thin films: A theoretical study looking forward low noise nano-devices

The resistivity of thin La_0.7Sr_0.3MnO₃ films was first investigated in a wide temperature (T) range (10–750 K). Films grown by different techniques and on several substrates enabled to analyze samples with different amounts of disorder. The aim of this work was to elucidate the nature of the metal–insulator (M–I) transition occurring at T = T_p in these films and its relation with the different kinds of inhomogeneities they could present like intrinsic electric disorder and co-existence of two different electrical and/or magnetic phases. The low-temperature resistivity state was described mostly by a law which scales as T with  ≈ 2.5. This supports the theoretical proposal of single magnon scattering in presence of minority spin states localized by the disorder. In the whole range of temperatures the experimental data are found to be consistent with a phase separation (PS) scenario. In order to go through the origin of the characteristic length scale of inhomogeneity found, preliminarily low frequency noise measurements as a function of T in a range of temperature around the M–I transition were made. The samples used were patterned using photolithography into bridges with various widths and lengths. No clear sign of separation phase dynamic has been observed in our noise measurements. Unexpectedly the normalized Hooge parameter _H/n was found not to be volume (Ω) independent. The LSMO electrical properties may strongly be driven by disorder and new design for magnetoresistance sensors may have to take into account their intrinsic PS.     

Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid

The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. −10° for Cd-PMA and ca. −15° for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.     

三水合氯化镨与18C6在乙醇中的配位行为及配合物的合成与表征

采用半微量相平衡方法研究了ＰｒＣｌ_３·３Ｈ_２Ｏ－１８Ｃ６－Ｃ_２Ｈ_５ＯＨ三元体系在２５℃的溶解度，测定了各饱和溶液的折光率。在该体系中有三种比学计量的配合物形成，其化学组成为：２ＰｒＣｌ_３·１８Ｃ６·６Ｈ_２Ｏ·Ｃ_２Ｈ_５ＯＨ、４ＰｒＣｌ_３·３（１８Ｃ６）·１２Ｈ_２Ｏ和ＰｒＣｌ_３·１８Ｃ６·３Ｈ_２Ｏ，依据相平衡结果，合成了三种固态配合物，利用化学分析、ＩＲ、ＴＧ、ＤＴＧ、ＤＳＣ及电导研究了配合物的组成和性质。     

Ground state pressure and energy density of an interacting homogeneous Bose gas in two dimensions

We consider an interacting homogeneous Bose gas at zero temperature in two spatial dimensions. The properties of the system can be calculated as an expansion in powers of g, where g is the coupling constant. We calculate the ground state pressure and the ground state energy density to second order in the quantum loop expansion. The renormalization group is used to sum up leading and subleading logarithms from all orders in perturbation theory. In the dilute limit, the renormalization group improved pressure and energy density are expansions in powers of the T ^2B and T ^2Bln(T ^2B), respectively, where T ^2B is the two-body T-matrix. Received 19 April 2002 Published online 13 August 2002     

Five-step phase-shifting algorithms with unknown values of phase shift

The presented work offers new algorithms for phase evaluation in interferometric measurements. Several phase-shifting algorithms with an arbitrary but constant phase-shift between captured intensity frames are proposed. These phase calculation algorithms need to measure five frames of the intensity of the interference field. The algorithms are similarly derived as so called Carré algorithm. The phase evaluation process then does not depend on the linear phase shift errors. Furthermore, the detailed analysis of the algorithms with respect to most important factors, which affect interferometric measurements, is carried out. It is also studied the dependency of the evaluation algorithms on the phase shift values, and the proposed phase calculation algorithms are compared with respect to the resulting phase errors. The influence of most important factors in the measurement and evaluation process was simulated as systematic and random errors using a proposed mathematical model.     

Stochastic modeling of unresolved scales in complex systems

Model uncertainties or simulation uncertainties occur in mathematical modeling of multiscale complex systems, since some mechanisms or scales are not represented (i.e., ‘unresolved’) due to a lack in our understanding of these mechanisms or limitations in computational power. The impact of these unresolved scales on the resolved scales needs to be parameterized or taken into account. A stochastic scheme is devised to take the effects of unresolved scales into account, in the context of solving nonlinear partial differential equations. An example is presented to demonstrate this strategy. Dedicated to Professor Peter E. Kloeden on the occasion of his 60th birthday