Uniform persistence of multispecies ecological competition predator-pray system with Holling Ⅲ type functional response

The main purpose of this paper is to study the persistence of the general multispecies competition predator-pray system with Holling Ⅲ type functional response.In this system,the competition among predator species and among prey species are simultaneously considered.By using the comparison theory and qualitative analysis,the sufficient conditions for uniform strong persistence are obtained.     

Pillar[5]arene based conjugated macrocycle polymers with unique photocatalytic selectivity

The development of heterogeneous catalysts with substrate shape, size or electronic constitution selectivity is a huge challenge in photocatalysis. Reported herein is a host-guest interaction strategy to endow photocatalysts with special selectivity. By adjusting the precursors, conjugated macrocycle polymers (CMPs) with pillar[5]arene struts (CMP-1 and CMP-2) and a corresponding non-pillar[5]arene-contained conjugated organic polymer (COP-1) were prepared and the photocatalytic activities toward sulfide derivatives were investigated. The sulfides showed similar conversions when COP-1 was used as a photocatalyst, but exhibited significant differences when it turned to the CMPs. Remarkably, the conversion yield of S-1 achieved near 18 folds over the one of S-2 when CMP-2 was used as a catalyst. Mechanism studies confirmed that the “host-guest” effect of pillar[5]arene struts in CMPs was the main cause of the difference. The present work establishes CMPs as novel heterogeneous photocatalysts with substrate selectivity, and such a method will inspire the researchers concerning preparation of heterogeneous catalysts with excellent selectivity.     

Selective C-alkylation Between Alcohols Catalyzed by N-Heterocyclic Carbene Molybdenum

The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H₂O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step.     

A New Method to Investigate the Clustering Phenomena in Supercritical Fluids

EstimationoflocaldensityofsolventaboutthesoluteSolvatochromicbehaviorsofspectroscopicprobesarewidelyusedtoestimatethesol-ventstrengthofsupercriticalfluids(SCF,).i-3lnthiswork,thesolvatochrondcshiftofthen-n*transitionbandforacetone(O.o37mo1.L-')insupercrihcal(SC)CO2wasde-terminedbyUVspectroscopytostUdythesolvationeffect.TheMcRae-BaylissexpressionbasedonthedielectriccontinUUInmodelgivestherelahonshipbetWeenso1vatochromicshiftandpo1arizabilityofnonPolarsolvents4-5asfollows:wherevisthewave…     

Study of Intramolecular Cyclization of N-styryl-oxo-cinnamides (Ⅱ)

lnthepreviouspaper',wereportedtheintramolecularcyclizationsofamide4anditscis-eneisomerinanattempttosynthesizehomoclausenamideandzetaclausenamide2.Inordertostudytherelationshipbetweenthestereochemistryandtheilltramolecularcyclizationofthisseriesofcompounds,theamides5(cis-oxirane,trans-ene)and8(cis-oxirane,cis-ene)wereprepared,andtheirintramolecularcyclizationswerereportedinthispaper.Theamide5withm.p.152.O-l54.O"CwasobtainedfromDarzen'scondensationofcompound3withPhCHOinMeOHatl5-2OoCwithMeO…     

Synthesis and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 as a concentration-gradient cathode material for lithium batteries

A well-ordered and spherical LiNi0.6Co0.2Mn0.2O2 cathode material was successfully synthesized from Ni and Mn concentration-gradient precursors via co-precipitation. The crystal structure, morphology and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and charge-discharge tests. The material delivered an initial discharge capacity of 174.3 mAh/g at 180 mA/g （1 C rate） between 2.8 and 4.3 V and more than 93.1% of that was retained after 100 cycles. In addition, it also exhibited excellent rate capability, high cut-off voltage and temperature performance.     

藏药柳茶叶乙醇水提取物中化学成分的鉴定

采用多种色谱分离技术对藏药柳茶叶80%乙醇提取物进行分离纯化,得到了9个化合物。 根据其理化性质与NMR谱数据对化合物进行了结构鉴定,分别为金丝桃苷（hyperoside,Ⅰ）、槲皮素（quercetin,Ⅱ）、芸香苷（rutin,Ⅲ）、槲皮素3-O-β-D-吡喃葡萄糖苷（quercetin-3-O-β-D-glucopyranoside,Ⅳ）、儿茶素（catechin,Ⅴ）、香草酸（vanillic acid,Ⅵ）、熊果苷（arbutin,Ⅶ）、异阿魏酸（isoferulic acid,Ⅷ）和胡萝卜苷（daucosterol,Ⅸ）。 化合物中除Ⅳ、Ⅷ和Ⅸ外,其余6个化合物为首次从该属植物中分离鉴别。     

聚乙烯吡咯烷酮对Pt/Ru双金属纳米簇的结构和催化性能影响

以乙二醇为还原剂,通过微波热辐射制备得到稳定的Pt/Ru双金属胶体纳米簇,各颗粒粒径在1~2 nm范围。考察了聚合物聚乙烯吡咯烷酮(PVP)对Pt/Ru双金属纳米簇表面原子组成及催化性能的影响。结果表明,PVP与金属前体之间的不同相互作用影响Pt/Ru双金属纳米簇的形成。在Pt/Ru双金属纳米簇形成之前加入PVP,Pt原子更容易富集在双金属表面,有利于增加Pt在催化反应中的作用。在PVP稳定的Pt/Ru双金属纳米簇中,除了零价态的Pt、Ru单质外,还存在氧化态的Pt化合物,归因于PVP与Pt前体的相互作用。在环己烯加氢反应中,PVP-Pt/Ru双金属纳米簇显示出比单金属纳米簇更优越的催化性能。     

Review: Separation and Pharmacology of Chiral Compounds in Traditional Chinese Medicine

More than 60% commonly used pharmaceutical active ingredients are chiral compounds. Developing more effective and safe chiral compounds has become a focus in the pharmaceutical industry. Chiral compounds widely exist in traditional Chinese medicine and include alkaloids, flavonoids, volatile oils, and amino acids. The characterization of chiral compounds used in traditional Chinese medicine remains limited. Here, the characterization of chiral compounds commonly used in traditional Chinese medicine is reviewed focusing upon their separation and pharmacology.