Dual variational principles with deviating argument and discontinuous extremals

We study dual or complementary variational principles for functionals with deviating argument and discontinuous extremals. Local conditions for the existence of a pair of dual extremum principles are given. Results are then applied to the control problem involving linear neutral differential-difference equations.     

对称群的分歧数据系统分类

含特征标的分歧数据系统能被用来分类PM箭图Hopf代数.本文给出了对称群Sn(n≠6)上含特征标的分歧数据系统的同构类个数的计算公式.     

烧成工艺对低压用BaTiO3基PTCR陶瓷性能的影响

采用固相反应法制备低压用BaTiO3基PTCR陶瓷。采用XRD、SEM分析陶瓷的相组成及表面形貌。研究了烧成工艺对陶瓷性能的影响。当烧成温度为1280℃,降温时低温保温温度为1045℃时,制备出低阻高耐压BaTiO3基PTCR陶瓷,其室温电阻率ρRT为36Ω·cm,温度系数α为13.8%/℃,耐电压强度E为100 V/mm。     

Evaluation of liquid chromatography–ion trap–time of flight hybrid mass spectrometry on the quantitative analysis for ginsenosides

It is ideal and desirable for a single instrument to meet the requirement of both qualitative and quantitative analysis of complicated components in pharmacokinetic research for herbal medicine. Liquid chromatography combined with hybrid ion trap and time‐of‐flight mass spectrometry (LCMS‐IT‐TOF) was recently confirmed as a very powerful tool for the qualitative analysis of both target and nontarget components in herbal medicines. The present study was designed to investigate the feasibility of LCMS‐IT‐TOF on quantitative analysis of ginsenosides in biological matrices. A simple liquid–liquid extraction procedure was followed by injection of the extracts onto a C₁₈ column with gradient elution and detection based on LCMS‐IT‐TOF system in negative scan mode. The developed method was validated with respect to the limit of quantification, linear dynamic range, precision, accuracy, matrix effects and stabilities. All the results suggested that the presently developed method was sufficiently sensitive and robust enough to simultaneously monitor 15 ginsenosides with diverse properties and a large range of concentration differences. Therefore, this method would be expected to be highly useful for comprehensive studies of ginsenosides in complicated matrix. Copyright © 2014 John Wiley & Sons, Ltd.     

Photoisomerization of a Maleonitrile‐Type Salen Schiff Base and Its Application in Fine‐Tuning Infinite Coordination Polymers

Strategically designed salen ligand 2,3‐bis[4‐(di‐p‐tolylamino)‐2‐hydroxybenzylideneamino]maleonitrile ( 1 ), which has pronounced excited‐state charge‐transfer properties, shows a previously unrecognized form of photoisomerization. On electronic excitation (denoted by an asterisk), 1Z *→ 1E isomerization takes place by rotation about the C2? C3 bond, which takes on single‐bond character due to the charge‐transfer reaction. The isomerization takes place nonadiabatically from the excited‐state ( 1Z ) to the ground‐state ( 1E ) potential‐energy surface in the singlet manifold; 1Z and 1E are neither thermally inconvertible at ambient temperature (25–30 °C), nor does photoinduced reverse 1E *→ 1Z (or 1Z *) isomerization occur. Isomers 1Z and 1E show very different coordination chemistry towards a Zn^II precursor. More prominent coordination chemistry is evidenced by a derivative of 1 bearing a carboxyl group, namely, N,N′‐dicyanoethenebis(salicylideneimine)dicarboxylic acid ( 2 ). Applying 2Z and its photoinduced isomer 2E as building blocks, we then demonstrate remarkable differences in morphology (sphere‐ and needlelike nanostructure, respectively) of their infinite coordination polymers with Zn^II.