静电复印用双偶氮颜料的研究

合成了含邻氯双偶氮颜料,借助元素分析、红外光谱、吸收光谱、X射线粉末衍射等对其结构与性能进行了表征,并制成了功能分离型结构的有机光导器件。光电特性显示,该器件对可见光有很好的敏感性,是一种良好的静电复印用有机光导材料。     

有机小分子不对称催化Michael加成的研究进展

有机小分子催化成为现在最热门的研究领域之一.不对称Michael加成反应是合成具有一个或多个手性中心合成砌块和药物中间体的重要方法.介绍了近3年来有机小分子伯胺衍生物、吡咯烷衍生物、(硫)脲、手性方酰胺和磷酸等在不对称催化Michael加成中的应用研究进展.对各种小分子结构和催化活性的关系、催化剂诱导活化机理以及各种催化体系在药物和关键中间体合成中的应用也进行详细的评述.     

Infrared electroluminescence from a Si MOS structure with Ge in the oxide

We report on room-temperature infrared electroluminescence (EL) from metal-oxide-semiconductor devices made from Si. We compare the luminescence from RF sputtered oxide films containing SiO₂ with and without Ge by using a composite target and luminescence from a SiO₂ layer made by rapid thermal oxidation. The sputtered films were annealed in the temperature range 600-900 °C. This densifies the films and is likely to reduce the concentration of defects. A luminescence peak located around 1150-1170 nm is observed at current densities as low as 0.1 A/cm². The corresponding photon energy is close to that of the Si band gap. In addition, we observe several broad luminescence bands in the range 1000-1750 nm. These bands get stronger with Ge in the SiO₂ film. Some of these bands have previously been suggested and are directly associated with Ge. Since we observe that the intensity is correlated with the presence of Ge while the mere presence of the bands is not, we discuss the EL bands being due to defects which concentration is influenced by Ge in the oxide.     

Novel self-assembled MgO nanosheet and its precursors

A novel self-assembled microstructure, nestlike Mg(5)(CO(3))(4)(OH)(2).4H(2)O spheres, is formed by a self-assembly of nanosheets in the hydrothermal process. MgO with the similar morphology can be obtained by calcination of nestlike Mg(5)(CO(3))(4)(OH)(2).4H(2)O. MgO precursors with a uniform, ellipsoid-shaped, and smooth surface or flowerlike architecture, built by individual thin sheets, can be well-obtained by carefully controlling pH values of the initial reaction solution. The nestlike MgO exhibits a unique geometrical shape; its surface is composed of uniform MgO nanosheets. The unique MgO microstructure with high surface areas may possess promising applications as the sorbent for chemisorption and destructive adsorption of various pollutants.     

Fabrication of polymeric micelles with core–shell–corona structure for applications in controlled drug release

Thermo-responsive polymeric micelles of poly (ethylene glycol)-b-poly(2-hydroxyethyl methacrylate-g-lactide)-b-poly(N-isopropylacrylamide) (PEG-P(HEMA-PLA)-PNIPAM) with core–shell–corona structure were fabricated for applications in controlled drug release. The graft copolymer of PEG-P(HEMA-PLA)-PNIPAM was self-assembled into core–shell micelles with a densely PLA core and mixed PEG/PNIPAM shells at 25 °C in aqueous media. By increasing the temperature above the lower critical solution temperature of PNIPAM, these core–shell micelles could be converted into core–shell–corona micelles because of the collapse of PNIPAM block on the PLA core as the inner shell and the soluble PEG block stretching outside as the outer corona. Anticancer drug doxorubicin (DOX) was loaded in the polymeric micelles as a model drug. Compared with polymeric micelles formed by liner PEG-b-PLA-b-PNIPAM triblock copolymer, these polymeric micelles exhibited higher loading capacity, and release of DOX from the polymeric micelles with core–shell–corona structure was well-controlled.     

广义紧向量场

本文是[1]的继续,主要研究固定的有界连续映象经紧连续映象摄动以后得到的广义紧向量场。我们沿用[1]的符号和术语,特别,采用如下基本假设: 设X、Z为线性赋范空间,Ω为Χ中有界开集。设I:→Z为确定的连续映象,且 设F:→Z紧连续,表f(x)=I(x)-F(x)。 首先建立广义紧向量场f(x)的平凡性和本质性判别法,特别是其中某些平凡性判别法,即使对Leray—Schauder映象而言,也是新结果。     

Brønsted Acid‐Mediated Annulation of α‐Oxo Ketene Dithioacetals with Pyrroles: Efficient Synthesis of Structurally Diverse Cyclopenta[b]pyrroles

Brønsted acid‐mediated annulation of internal olefins α‐oxo ketene dithioacetals to pyrroles was efficiently achieved to afford cyclopenta[b]pyrroles. A pair of Brønsted acids with acid strengths, that is, trifluoroacetic acid, and para‐toluenesulfonic acid hydrate, were applied to promote the annulation reactions. The resultant products were readily oxidized to sulfones by meta‐chloroperoxybenzoic acid. Subsequent treatment with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene gave desulfurized terminal olefins or [2+2] cycloaddition products from the desulfurized olefin intermediates. The present protocol provides facile access to structurally diverse cyclopenta[b]pyrrole derivatives under mild conditions.     

Characterization of the dehydration products due to thermal decomposition of peptides by liquid chromatography‐tandem mass spectrometry

Thermal decomposition (TD) of proteins is being investigated as a rapid digestion step for bottom‐up proteomics. Mass spectrometry (MS) analyses of the TD products of simple peptides and intact proteins have revealed several nonvolatile products at masses lower than the precursor biomolecule (M). In addition to products stemming from site‐specific cleavages, many signals are also observed at a corresponding M‐18, most likely because of dehydration (M‐H₂O) during the heating process. Understanding the structural nature of the water loss product is important in establishing the utility of their tandem mass spectra (collision‐induced dissociation) in determining the precursor ion amino acid sequence in a bottom‐up proteomic workflow. Dehydration of a peptide can take place from a variety of sources including side chain groups, C‐terminus, and/or intramolecular cyclization (C to N‐terminus cyclization). In this work, liquid chromatography‐tandem MS (LC‐MS/MS) and a series of standard peptides (angiotensin II, DRVYIHPF and its cyclic analog) are implemented to decipher the structure of the TD dehydration product. In addition, a derivatization strategy incorporating N‐terminus acetylation was developed that allowed the direct comparison of tandem mass spectra of standard cyclic peptides with those resulting from the TD process, thus eliminating any ambiguity from the direct comparison of their mass spectra (due to gas‐phase cyclization of b‐ions, which can result in sequence scrambling of the precursor ion). Results from these investigations indicated that peptide dehydrated TD products were mostly linear in nature, and water loss was favored from the C‐terminus carboxyl group or, when present, the aspartic acid side chain. Given the predictable nature of the formation of TD dehydration products, their MS/MS analysis can be of utility in providing complementary and confirmatory sequence information of the precursor peptide. Copyright © 2015 John Wiley & Sons, Ltd.     

The new result on delayed finance system

In this paper, a finance system with time delay is considered. By linearizing the system at the unique equilibrium and analyzing the associated characteristic equation, the asymptotic stability of the unique equilibrium is investigated and Hopf bifurcations are demonstrated. Furthermore, the direction of Hopf bifurcation and the stability of the bifurcating periodic solutions are determined by the normal form theory and the center manifold theorem for functional differential equations. Finally, some numerical simulations are carried out for illustrating the theoretical results.     

采用超薄双层靶提高质子束的单能性

利用1维粒子模拟程序,研究了超短超强激光脉冲与超薄双层靶(基底层和加速层厚度均为nm量级)相互作用产生准单能质子束的过程。研究表明,基底层厚度及加速层厚度对质子能谱的影响至关重要。减小基底层厚度,靶后静电场增强,质子的最大能量显著增大;减小加速层厚度,靶后静电场分布变得更加均匀,质子能谱中心能量变化不大,单能性变好。通过优化参数,获得了能散度为7%的准单能质子束。