高阶单步A-稳定指数拟合法

In this paper,the necessary and sutlicient conditions for general one-step methoos to be exponentially fitted at q0∈C are given, A class of multtderivative hybrid one-step methods of order at least s 1 is constructed with s 1 parameters,where s is the order of derivative. The necessary and sufficient conditions for these methods to be A-stable and exponentially fitted is proved, Furthermore,a class of A-stable 2 parameters hybrid one-step methods of order at least 8 are constructed,which use 4th order derivative,These methods are exponentially fitted at q0 if and only its fitted function f(q) satisfies f(q0)= 0, Finally,an A-stable exponentlally fitted method of order 8 is obtained.     

非线性掺铒光纤环镜中超短光孤子串的产生及放大

利用数值模拟方法证明了,双频弱连续波的拍频信号在分布增益的非线性掺铒光纤环镜内传输,能产生超短光孤子串.数值计算表明,当输入信号为重复率<20 GHz的拍频弱信号时,可在较短的环镜长度内产生占空比大且高质量的光孤子串.研究同时发现,输入信号的平均功率越大,所需环镜长度越短.与其他方法相比,该方法不仅能克服传统方法所产生的脉冲重复率受限的困难,而且在无需采用特种光纤的情况下,将弱信号转化为超短光孤子串.     

关于序超半群的左超理想的研究

本文在序超半群中引入了极小左超理想和极大左超理想的概念, 并讨论了它们的一些相关性质. 进一步地, 引入了序超半群的弱素左超理想、拟素左超理想、拟半素左超理想及弱拟素左超理想的概念, 并讨论这四种素超理想之间的关系. 而且通过左超理想和弱~$m$-系刻画了序超半群的弱拟素左超理想. 同时, 借助于$m$-系对序超半群的拟素左超理想给出刻画. 尤其证明了序超半群$S$是强半单的当且仅当$S$的每个左超理想是$S$的包含它的所有拟素左超理想的交.     

Preparation and characterization of polyurethan‐block‐poly(trifluoro‐ propylmethyl)siloxane elastomers

A series of polyurethane‐block‐poly(trifluoropropylmethyl)siloxane (PUFS) elastomers were prepared via a two‐step process from toluenediisocyanate (TDI), α ω‐bis(3‐aminopropyldiethoxylsilane) poly(trifluoropropylmethyl)siloxane (APFS), and poly(tetramethylene oxide) (PTMO). The PUFS films were formed through moisture curing and characterized by DSC, DMTA, TGA, mechanical testing, and water contact angle. It was found that the extent of microphase separation of the PUFS system would increase with the increase in APFS content, and result in the decrease in the tensile strength and the thermal stability. On the other hand, the crosslink density of the PUFS system would apparently increase with the increase in the TDI content, which reduced the microphase separation and improved the tensile properties and the thermal stability of the PUFS elastomers. Copyright © 2009 John Wiley & Sons, Ltd.     

Curvature-regulated transmembrane anion transport by a trifluoromethylated bisbenzimidazole

In this paper,we demonstrate that modification of anion-transport active 1,3-bis(benzimidazol-2-yl)benzene with strongly electron-withdrawing trifluoromethyl and nitro groups leads to a dramatic increase in the anionophoric activity,and the activity may be greatly regulated by the curvatures of the liposomes used.     

Applications of metal-organic framework composites in CO_2 capture and conversion

Reliable technologies for CO_2 capture and conversion(C3) are of vital importance for the establishment of a sustainable society.Metal-organic framework(MOF) composites have shown their compelling potentials for C3 due to the plentiful reticular chemistry of MOF structures and the synergistic catalysis between MOFs and the functional guests.This review focuses on the syntheses and catalytic applications towards C3 of MOF composites,which is divided into three sections.The first section gives a brief introduction about synthetic strategies of MOF composites.The second section discusses the recent progress of MOF composites in C3,including CO_2 chemical fixation,hydrogenation,photoreduction,electro reduction and photoelectro reduction.The third section summarizes the challenges and future prospects of MOF composites for C3.We hope that this review cannot only provide an inspiration for the rational design of MOF composites for C3,but also stimulate more and more research works in this emerging area.     

Unprecedented Multicomponent Reaction of Indoles,CS2 and Nitroarenes: Stereoselective Synthesis of (Z)-3-((Arylamino)methylene)indoline-2-thiones

An efficient method for the stereoselective synthesis of (Z)-3-((arylamino)methylene)indoline-2-thiones have been developed via a novel multicomponent reaction of indoles, CS₂ and nitroarenes. A range of functionalized indoline-2-thiones were prepared in moderate to good yields from easily available starting materials. The indoline-2-thione products can be easily derivatized to give biologically active thieno[2,3-b]indole and thiopyrano[2,3-b]indole skeletons in high yields.     

Fluorescence Enhancement of a Metal-Organic Framework for Ultra-Efficient Detection of Trace Benzene Vapor

Indoor detection of volatile organic compounds (VOCs) concentration is necessary due to the serious toxicity hazards even at trace level. However, physisorbents usually exhibit weak interactions especially in the presence of trace concentrations of VOCs, thus exhibiting poor responsive signal. Herein, we report a new flexible metal–organic framework (MOF) that exhibits interesting pore-opening behavior after immersing in H₂O. The pore-opening phase shows significant (≈116 folds) and extremely fast (<1 minute) fluorescence enhancement after being exposed to saturated benzene vapor. The limit of detection concentration for benzene vapor can be calculated as 0.133 mg L⁻¹. Thus this material represents the first MOF to achieve visual detection of trace benzene vapor by the naked eyes. Theoretical calculations and single-crystal structure reveal that the special “bilateral π–π stacking” interactions between the host and guest, which facilitate electron transfer and greatly enhance the intensity of fluorescence.     

一种实用的实验室电源的设计

介绍了一种实用的物理实验专用线性可调稳压直流电源。该电源由可调三端稳压、可调基准电压、限流电路等构成,可提供0～12 V连续可调电压,输出电流限制在100 mA,适用于大学物理实验中二极管伏安特性测量、三用电表的设计与制作等设计性实验,起到对实验器件和仪表的保护作用。     

纳米VO2/ZnO复合薄膜的热致变色特性研究

为提高VO₂薄膜的热致变色性能,采用纳米结构和复合结构二者相结合的方法,通过磁控溅射技术先在玻璃衬底上制备高(002)取向ZnO薄膜,再在ZnO层上室温沉积钒金属薄膜,最后经热氧化处理获得纳米结构VO₂/ZnO复合薄膜.利用变温拉曼光谱观察分析了VO₂/ZnO薄膜相变前后的晶格畸变和键态的演变过程,讨论了薄膜的结构与热致红外开关特性和相变温度的内在关系.结果显示,与相同条件获得的同厚度的单层VO₂薄膜相比,纳米VO关键词： ZnO 2')" href="#">VO₂ 纳米复合薄膜 热致变色 拉曼光谱