一类Hermitian鞍点矩阵的特征值估计

本文研究了一类大型稀疏Hermitian鞍点线性系统Az=(B E E* 0)(x y)=(f g)=b系数矩阵的特征值,其中B∈C~(p×p)是Hermitian正定阵矩阵,E∈C~(p×q)是列降秩.本文分别给出了该系数矩阵正特征值与负特征值界的一个估计式,同时通过数值算例验证本文所给出的特征值界的估计是合理且有效的.     

Synthesis of quinazolinones from anthranilamides and aldehydes via metal-free aerobic oxidation in DMSO

A highly environmentally benign protocol for the synthesis of quinazolinones from anthranilamides and aldehydes via aerobic oxidation was developed in wet DMSO. This protocol is operationally simple, exhibits broad substrate scope, and does not need toxic metal catalysts and bases. In addition, the utility of this transformation was further demonstrated by converting the resulting quinazolinones into other useful products in the same-pot without their isolation.     

基于遗传编程方法的微孔磷酸铝的定向合成研究

根据微孔磷酸铝合成数据的特点,针对合成数据库中合成参数过多和交叉描述等问题,利用改进的遗传编程算法对具有(6,8)元环的微孔磷酸铝合成参数进行特征提取,优化出新的复合特征来更好地描述磷酸铝合成中溶剂和模板剂的特征,并通过参数进化过程的研究,考察了模板剂和溶剂对产物生成的具体影响,从而指导具有特定结构磷酸铝的定向合成.     

一种可用于光降解的纳米氧化锌油水分离网

通过低温水热法在钢丝网上生长六棱柱形的氧化锌纳米柱.包覆了氧化锌纳米柱的钢丝网具有水下超疏油的特殊浸润性,并可用于油水分离.滤网在室温常压下可对含有汽油、柴油和原油等油水混合物进行高效快速分离,分离效率可达98%以上.材料可以承受1.4 kPa的油层压力且可反复使用.由于氧化锌的光响应性强,滤网可快速降解水中的亚甲基蓝,2 h的降解率可达80%.包覆了氧化锌纳米柱的钢丝网具备同时进行油水分离和降解环境中污染物的能力,是一种新型多功能水处理材料.     

共存牺牲剂对染料敏化TiO_2纳米晶体系电子传输的影响

采用卟啉染料敏化TiO2纳米晶在可见光条件下(λ390 nm)进行水分解制氢.考察了不同牺牲剂———甲醇(MeOH)、三乙醇胺(TEOA)及其混合物对体系析氢效率的影响.通过荧光猝灭及光电化学性能分析发现,激发态染料与TiO2之间的电子转移极大地受到添加的牺牲剂的影响,而体系的pH值对其影响不大.     

聚乙烯醇/壳聚糖复合水凝胶的物理化学性质

测定了聚乙烯醇(PVA)和壳聚糖(CS)复合水凝胶的平衡含水量、熔融焓、等温溶胀动力学和非等温失水动力学等性质,讨论了水凝胶的组成和制备参数对这些性质的影响.结果显示:PVA/CS复合水凝胶具有适宜于软骨修复替代材料的网络结构和平衡含水量.CS与PVA复合减弱了凝胶的结晶度,但却增强了水与凝胶支架的相互作用.尽管水凝胶力学拉伸强度有所降低,但却优化了凝胶的生物相容性和降解能力.PVA/CS复合水凝胶是一种潜在的软骨修复材料,作为一种理论研究的模型体系,它将促进热力学在复杂医用材料方面的应用.     

Preparation of Yolk‐Shell and Filled Co9S8 Microspheres and Comparison of their Electrochemical Properties

In this study, we report the first preparation of phase‐pure Co₉S₈ yolk–shell microspheres in a facile two‐step process and their improved electrochemical properties. Yolk–shell Co₃O₄ precursor microspheres are initially obtained by spray pyrolysis and are subsequently transformed into Co₉S₈ yolk–shell microspheres by simple sulfidation in the presence of thiourea as a sulfur source at 350 °C under a reducing atmosphere. For comparison, filled Co₉S₈ microspheres were also prepared using the same procedure but in the absence of sucrose during the spray pyrolysis. The prepared yolk–shell Co₉S₈ microspheres exhibited a Brunauer–Emmett–Teller (BET) specific surface area of 18 m² g^?1 with a mean pore size of 16 nm. The yolk–shell Co₉S₈ microspheres have initial discharge and charge capacities of 1008 and 767 mA h g^?1 at a current density of 1000 mA g^?1, respectively, while the filled Co₉S₈ microspheres have initial discharge and charge capacities of 838 and 638 mA h g^?1, respectively. After 100 cycles, the discharge capacities of the yolk–shell and filled microspheres are 634 and 434 mA h g^?1, respectively, and the corresponding capacity retentions after the first cycle are 82 % and 66 %.     

Polypeptide‐b‐Poly(Phenyl Isocyanide) Hybrid Rod‐Rod Copolymers: One‐Pot Synthesis,Self‐Assembly,and Cell Imaging

Hybrid rod‐rod diblock copolymers, poly(γ‐benzyl L‐glutamate)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PBLG‐PPI), with determined chirality are facilely synthesized through sequential copolymerization of γ‐benzyl‐L‐glutamate N‐carboxyanhydride (BLG‐NCA) and phenyl isocyanide monomers bearing chiral menthyl pendants using a Ni(cod)(bpy) complex as the catalyst in one‐pot. Circular dichroism and absorption spectra reveal that each block of the block copolymers possesses a stable helical conformation with controlled helicity in solution due to the induction of chiral pendants. The two diastereomeric polymers self‐assemble into helical nanofibrils with opposite handedness due to the different chiral induction of the L‐ and D‐menthyl pendants, confirmed by transmission electron micro­scopy (TEM). Deprotection of the benzyl groups of the PBLG segment affords biocompatible amphiphilic diblock copolymers, poly(L‐glutamic acid)‐poly(4‐cyano‐benzoic acid 2‐isopropyl‐5‐methyl‐cyclohexyl ester) (PLGA‐PPI), that can self‐assemble into well‐defined micelles by cosolvent induced aggregation. Very interestingly, a chiral rhodamine chromophores RhB(D) can be selectively encapsulated into the chiral polymeric micelles, which is efficiently internalized into living cells when directly monitored with a confocal microscope. This contribution will be useful for developing novel rod‐rod biocompatible hybrid block copolymers with a controlled helicity, and may also provide unique chiral materials for potential bio‐medical applications.

     

Raman spectroscopy measurement of levofloxacin lactate in blood using an optical fiber nano‐probe

Liquid chromatography and mass spectrometry were time‐consuming and expensive as the main methods for the drug analysis at present, and the samples must be pretreated. The Raman spectroscopy measurement methods were fast and simple, so the Raman spectroscopy methods for the drug analysis were explored in this paper. An optical fiber nano‐probe coated with gold nanoparticles was fabricated and used with surface‐enhanced Raman spectroscopy (SERS) to measure levofloxacin lactate. The resulting SERS spectra of levofloxacin lactate in mouse blood that was detected by the optical fiber nano‐probe clearly showed the characteristic wave numbers of levofloxacin lactate, indicating that optical fiber nano‐probes can be used with spectral techniques to analyze drugs in vitro or potentially even in vivo. Copyright © 2015 John Wiley & Sons, Ltd.     

Preparation and electrochemical sensing performances toward bromate and Cr(VI) of two γ-octamolybdate-based complexes decorated by in situ transformation ligand

Transition Metal Chemistry - Two octamolybdate-based complexes formulated by [M2(H2O)4(γ-Mo8O26)(HDIBA)2]·H2O [M?=?Co (1), Zn (2),...