2,5-双(乙炔基二茂铁)噻吩/钨磷杂多酸纳米杂化LB膜的制备与光电性质研究

以含有共轭大π键的2,5-双(乙炔基二茂铁)噻吩(BFET)和二甲基双十八烷基铵(DMDOA)与Keggin结构和Dawson结构钨磷杂多酸做成膜材料, 用LB技术组装了两种新型无机-有机杂化LB膜. 用π-A曲线、UV-vis吸收光谱、原子力显微镜(AFM)、扫描隧道显微镜(STM)、荧光光谱和表面光电压谱(SPS)对标题LB膜的成膜性能、结构及光电性质进行了研究, 发现标题杂化LB膜的粒子具有纳米尺寸, 在可见光区有较强的光电压响应, 在电压为±2.0 V时, 隧道电流值达到±100 nA.     

Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization

Replaceable sieving polymers are the fundamental component for high‐resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well‐defined polymers previously unattainable by conventional free‐radical polymerization. In this study, a high molecular weight poly‐(N,N‐dimethylacrylamide) (PDMA) at 765 000 gmol^?1 with a polydispersity index of 1.55 was successfully synthesized with the use of chain transfer agent—2‐propionic acidyl butyl trithiocarbonate in a multistep sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high‐resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of 2‐propionic acidyl butyl trithiocarbonate PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP?‐CAP, of similar molecular weight range.     

Testing heteroscedasticity by wavelets in a nonparametric regression model

In the nonparametric regression models, a homoscedastic structure is usually assumed. However, the homoscedasticity cannot be guaranteed a priori. Hence, testing the heteroscedasticity is needed. In this paper we propose a consistent nonparametric test for heteroscedasticity, based on wavelets. The empirical wavelet coefficients of the conditional variance in a regression model are defined first. Then they are shown to be asymptotically normal, based on which a test statistic for the heteroscedasticity is constructed by using Fan's wavelet thresholding idea. Simulations show that our test is superior to the traditional nonparametric test.     

偏振-同步荧光法同时测定(艹屈)、蒽和苝

在荧光分光光度计的激发和发射光路中分别置入偏振互为垂直的偏振片,能有效地抑制同步扫描过程中散射光的影响。建立了(艹屈)蒽和苝的同时偏振-同步荧光分析法,其检出限改善3.9倍,相对标准偏差小于3.1%。     

Phase space generalization of the de Broglie-Bohm model

A generalization of the familiar de Broglie-Bohm interpretation of quantum mechanics is formulated, based on relinquishing the momentum relationship p=∇S and allowing a spread of momentum values at each position. The development of this framework also provides a new perspective on the well-known question of joint distributions for quantum mechanics. It is shown that, for an extension of the original model to be physically acceptable and consistent with experiment, it is necessary to impose certain restrictions on the associated joint distribution for particle positions and momenta. These requirements thereby define a new class of possible models. In pursuing this line of reasoning, the main contributions of this paper are (i) to identify the restrictions that must be imposed, (ii) to demonstrate that joint distribution expressions satisfying them do exist, and (iii) to construct a sample model based on one such joint distribution.     

Bell's theorem and backwards-in-time causality

Bell has shown that quantum mechanics is incompatible with the notion of locality. The present paper begins by considering the possibility of invoking backwards-in-time causality to explain this violation of locality. This then leads to an examination of the possible relevance of backwards-in-time causality to measurement outcomes in general. It is found that the situations in which it could be involved are limited owing to causality paradoxes.