Isobaric vapour–liquid equilibrium for the binary systems formed by a cyclic ether and bromocyclohexane at 40.0 and 101.3 kPa

Experimental data of vapour–liquid equilibrium (VLE) for the binary systems tetrahydrofuran, or tetrahydropyran, or 2-methyl-tetrahydrofuran, or 2,5-dimethyl-tetrahydrofuran with bromocyclohexane have been measured in isobaric conditions at two pressures, 40.0 and 101.3?kPa. The equipment used was a dynamic recirculating still. The consistency of the measured VLE data has been tested with the Van Ness’ point-to-point method. The activity coefficients have been correlated with the mole fraction through Wilson, NRTL and UNIQUAC equations.     

Study of redox behavior of Cd(II) and interaction of Cd(II) with proline in the aqueous medium using cyclic voltammetry

The redox behavior of Cd(II) and the interaction of Cd(II) with cyclic amino acid, proline, have been studied in 0.1 M KCl, 0.1 M NaClO₄ and acetate buffer of different pH. The CVs were recorded at glassy carbon electrode within the potential window 200 and ?1500 mV. The reference and counter electrode used were Ag/AgCl and Pt wire, respectively. The cyclic voltammograms show one pair of cathodic and anodic peaks for the Cd(II)/Cd(0) system indicating the involvement of two electron transfer processes. The peak potential shift and charge transfer rate constant (k_f) values strongly support the interaction between metal and ligand. The higher value of peak current ratio and peak potential separation (ΔE) indicate that the systems are quasireversible. The effect of supporting electrolyte and concentration of electro active species on the interaction were also studied.     

Solution-phase synthesis of novel seven-membered cyclic dipeptides containing α- and β-amino acids

A convenient synthetic procedure for the preparation of seven-membered cyclic α,β-dipeptides is described. Following coupling of N-protected α-amino acids with N-substituted β-amino acid tert-butyl esters, that affords linear α,β-dipeptides, the protecting groups at the terminal functionalities were removed and the open-chain dipeptides were cyclized with phenylphosphonic dichloride, PhP(O)Cl₂, to give the desired cyclic α,β-dipeptides in good yields. NMR studies, X-ray diffraction analysis, and DFT calculations provided evidence for the conformation adopted by these cyclic dipeptides in solution, in the solid-state, and in the gas phase.     

On Some Brauer Subgroups Arising From Twists of Matrix Algebras

We study some relations between groups of continuous characters and subgroups of Brauer groups. Explicit determination of some subgroups of Brauer groups arising from this connection are done for some cases in the local fields via local class field theory.     

Resolutions of 2 and 3 Dimensional Rings of Invariants for Cyclic Groups

Let G be the cyclic group of order n, and suppose F is a field containing a primitive nth root of unity. We consider the ring of invariants F[W] ^G of a three dimensional representation W of G where G ? SL(W). We describe minimal generators and relations for this ring and prove that the lead terms of the relations are quadratic. These minimal generators for the relations form a Gröbner basis with a surprisingly simple combinatorial structure. We describe the graded Betti numbers for a minimal free resolution of F[W] ^G . The case where W is any two dimensional representation of G is also handled.     

Dykstras algorithm with bregman projections: A convergence proof

Dykstra’s algorithm and the method of cyclic Bregman projections are often employed to solve best approximation and convex feasibility problems, which are fundamental in mathematics and the physical sciences. Censor and Reich very recently suggested a synthesis of these methods, Dykstra’s algorithm with Bregman projections, to tackle a non-orthogonal best approximation problem, They obtained convergence when each constraint is a halfspace. It is shown here that this new algorithm works for general closed convex constraints; this complements Censor and Reich’s result and relates to a framework by Tseng. The proof rests on Boyle and Dykstra’s original work and on strong properties of Bregman distances corresponding to Legendre functions. Special cases and observations simplifying the implementation of the algorithm are aiso discussed     

Voltammetric Determination of Epinephrine in the Presence of Uric Acid Based on Aminated Graphene and Ag NPs Hybrid Membrane Modified Electrode

A hybrid membrane consisted of aminated graphene and Ag nanoparticles（Ag NPs） was prepared on the surface of glassy carbon electrode（GCE） by cyclic voltammetry（CV） with aminated graphene（GR-NH2） as matrix for immobilizing Ag NPs.The morphology and electrochemical properties of this hybrid membrane were characterized by scanning electron microscopy（SEM） and CV,respectively,and on this membrane,the voltammetric behaviors of epinephrine（EP） were studied in detail.The membrane exhibited excellent eletro-catalytic activities for the redox of EP,and could resolve the electrochemical response of EP and uric acid（UA） into two oxidation peaks.The peak current of EP was linear with its concentration in the ranges of 0.916-18.3 μmol/L and 18.3-184 μmol/L.The detection limit was 2.0 nmol/L（S/N=3）.The proposed modified electrode retained the advantages of easy fabrication,high sensitivity and good repeatability for the determination of EP.     

吖啶酮类衍生物的光电性质研究

测定了8个吖啶酮类衍生物的紫外吸收光谱、荧光光谱和荧光量子产率,以研究它们的结构与光学性质之间的关系,用循环伏安法测出它们各自的电子势．发现吖啶酮类衍生物都具有较高的电子亲和势,表现出比常用的电子传输材料2-(4-联苯基)-5-(叔丁苯基1—1,3,4-二唑(PBD)更容易被还原的优良电化学性能。