SU(6)破缺效应对核子形状因子的贡献

最近杰斐逊实验室测量了中子的两个弹性电磁形状因子之比GEn/GMn,它反映了中子内部的电磁分布并能帮助理解中子的内部结构.传统的相对论组分夸克模型在解释质子的两种电磁形状因子之比GEp/GMp是很成功的,但在解释中子的该比值时计算值比实验值要低.为了解释这种现象,我们在相对论组分夸克模型框架下计算考察了SU(6)破缺效应的贡献.发现考虑该破缺效应后的计算结果同实验符合有明显改善.     

DSC Study on Brain Tubulin and the Effect of Cisplatin

Microtubules, a class of cytoskeletal elements, appear to be present in all eukaryoticcells. The temporal and spatial control of assembly and disassembly of microtubulesis believed to be a key factor in cellular function. Microtubules and their subunits(Q-0 tubulin heterodimers, MW 1 10,000) maintain a dynamic equilibrium in the cellcytoplasm. In addition, it is postulated that the lability of cytoplasmic microtubulescaused by drug is related to their equilibrium. Calorimetry method has been…     

Improvement of Selectivity with Boric Acid in Separating Phenolic Acids by Capillary Zone Electrophoresis

IntroductionTilersarevariousorgamcacidsintheextractsfromChineseadditionalplantmedicines.1Manyphenolicacids,suchasferulicacid,clllorogenicacid.vanillicacid,phydroxybenzoicacid,gallicacid,andprotocatechulcacidarefrequentlymet.AnalysisoftheseacidscanhelpinevaluatingalequalityoftileInedicine.CEisarecentlydevelopedtechniqueclmcterizedwithhighseparahonefficiency,shortanalysistime,lesssampleconsumption,minimalsamplepretrChtlnent,lowcost,andeaseofmodechange-overandcolumnregenefation.Studiesintillsar…     

Asymmetric syntheses of the methyl glycosides of 2-deoxy-2-aminohexoses: d-allosamine, d-mannosamine, d-idosamine and d-talosamine

A range of the methyl glycosides of 2-deoxy-2-aminohexoses, comprising d-allosamine, d-mannosamine, d-idosamine and d-talosamine, were prepared from the corresponding d-aldopentoses via a seven step synthetic sequence. The doubly diastereoselective conjugate addition of the requisite antipode of lithium N-benzyl-N-(α-methylbenzyl)amide and in situ enolate oxidation with the requisite antipode of camphorsulfonyloxaziridine (CSO) was used as the key, stereodefining step. Sequential reduction of the resultant α-hydroxy-β-amino esters and oxidative cleavage of the C(1)–C(2) diol unit furnished the corresponding α-amino aldehydes. Subsequent N- and O-deprotection gave the target compounds (as mixtures of anomers) in good yield and high diastereoisomeric purity.     

Are Triphenylamine‐Functionalized or Carbazole‐Functionalized Iridium Complexes the More Effective Phosphorescent Materials? A Theoretical Perspective

The ground and excited states, charge injection/transport, and phosphorescence properties of eleven carbazole‐ and triphenylamine‐functionalized Ir^III complexes were investigated by using the DFT method. By analyzing the spin–orbit coupling (SOC) matrix elements, radiative decay rate constants k_r, and the electronic structures and energies at the ${{\rm{S}}_{\rm{0}}^{{\rm{opt}}} }$ and ${{\rm{T}}_{\rm{1}}^{{\rm{opt}}} }$ states, it was possible to rationalize the order of the experimental phosphorescence quantum yields of a series of Ir^III complexes and to predict that [Ir(Nph‐2‐Cz‐tz)₃] has a higher phosphorescence quantum yield than [Ir(TPA‐tz)₃] (TPA=triphenylamine, tz=thiazolyl, Cz=carbazole, Nph=N‐phenyl). Carbazole‐functionalized Ir^III complexes were shown to be efficient phosphorescent materials that have not only fast but also balanced electron/hole‐transport performance as well as high phosphorescence quantum yields. The phosphorescence emission spectra can be modulated by modifying or replacing a pyridyl substituent.     

环氧化物法制备锑掺杂氧化锡气凝胶

以无机金属盐为前驱体,采用环氧丙烷添加法结合CO2超临界流体干燥和热处理工艺,制备了不同锑掺杂浓度的二氧化锡(ATO)气凝胶.所得气凝胶为深蓝色块体,平均密度约为600 mg?cm-3,锑掺杂浓度在5%到20%(x)之间.电子显微镜图片显示ATO气凝胶的骨架由粒径约为数十纳米的颗粒堆积而成,而这些颗粒又由数纳米的初级球形颗粒构成.X射线衍射谱表明,样品的主要晶相为SnO2四方相金红石结构,锑的掺杂仅引起微小的晶格畸变.X射线光电子谱显示锡元素以+4价态存在,而锑则具有+3和+5的混合价态.四探针电阻率测试仪的结果表明,ATO气凝胶的电阻率在2.7-40Ω?cm之间变化,其中在锑掺杂浓度(x)为12%时具有最低电阻率.     

Facile synthesis and characterization of high-performance NiMoO<Subscript>4</Subscript> · <Emphasis Type="Italic">x</Emphasis>H<Subscript>2</Subscript>O nanorods electrode material for supercapacitors

One-dimensional NiMoO₄ · xH₂O nanorods were synthesized by a facile template-free hydrothermal method as a potential electrode material for supercapacitors. The influences of reaction temperature, reaction time, and nickel source on the properties of resultant samples were investigated. Electrochemical data reveal that the as-synthesized one-dimensional NiMoO₄ · xH₂O nanorod superstructures can deliver a remarkable specific capacitance (SC) of 1131 F g^?1 at a current density of 1 A g^?1 and remain as high as 914 F g^?1 at 10 A g^?1 in a 6 M KOH aqueous solution. Moreover, there is only 6.2 % loss of the maximum SC after 1000 continuous charge–discharge cycles at the high current density of 10 A g^?1. Such outstanding electrochemical performance may be owing to the unique one-dimensional hierarchical structures, which can facilitate the electrolyte ions and electrons to easily contact the NiMoO₄ nanorod building blocks and then allow for sufficient faradaic reactions to take place, even at high current densities.     

Protein-directed in situ synthesis of platinum nanoparticles with superior peroxidase-like activity,and their use for photometric determination of hydrogen peroxide

Platinum nanoparticles (Pt-NPs) with sizes in the range from 10 to 30 nm were synthesized using protein-directed one-pot reduction. The model globular protein bovine serum albumin (BSA) was exploited as the template, and the resulting BSA/Pt-NPs were studied by transmission electron microscopy, energy dispersive X-ray spectroscopy, and resonance Rayleigh scattering spectroscopy. The modified nanoparticles display a peroxidase-like activity that was exploited in a rapid method for the colorimetric determination of hydrogen peroxide which can be detected in the 50 μM to 3 mM concentration range. The limit of detection is 7.9 μM, and the lowest concentration that can be visually detected is 200 μM.

Pt-NPs were synthesized using BSA-directed one-pot reduction and BSA/Pt-NPs composite can effectively catalyze the oxidation of TMB producing blue solution in the presence of H₂O₂.

     

Solid‐State Condensation Reactions Between Aldehydes and 5,5‐Dimethyl‐1,3‐cyclohexanedione by Grinding at Room Temperature

An efficient and convenient approach to the synthesis of the two different products from aldehydes and 5,5‐dimethyl‐1,3‐cyclohexanedione in the solid state by grinding is described. This method provides several advantages such as environmental friendliness, high yields, and simple workup procedure.     

Trading N and O: asymmetric syntheses of β-hydroxy-α-amino acids via α-hydroxy-β-amino esters

Both diastereoisomers of 2-amino-3-hydroxybutanoic acid and 2-amino-3-hydroxy-3-phenylpropanoic acid have been prepared from enantiopure α-hydroxy-β-amino esters via the intermediacy of the corresponding cis- and trans-aziridines. Aminohydroxylation of two α,β-unsaturated esters produced enantiopure 2,3-anti-α-hydroxy-β-amino esters in >99:1 dr. Subsequent epimerisation at the C(2)-position via a sequential oxidation/diastereoselective reduction protocol gave the corresponding enantiopure 2,3-syn-α-hydroxy-β-amino esters in >99:1 dr. These syn- and anti-substrates were then converted into the corresponding N-Boc protected cis- and trans-aziridines, respectively, via a three step reaction sequence: (i) hydrogenolysis and in situ N-Boc protection; (ii) OH-activation; and (iii) aziridine formation. Subsequent regioselective ring-opening of the C(3)-methyl-aziridines with Cl₃CCO₂H proceeded with inversion of configuration to give the corresponding 2-amino-3-trichloroacetate esters, whereas the analogous reaction with the C(3)-phenyl-aziridines resulted in rearrangement to the corresponding oxazolidin-2-ones with retention of configuration. In each case, hydrolysis of the products from these ring-opening reactions produced the corresponding enantiopure β-hydroxy-α-amino acids as single diastereoisomers.