新的聚苯乙烯负载锌化合物:高效苯酚氧化催化剂(英文)

The novel recyclable free –ONNO– tetradentate Schiff base ligand N,N′‐bis(2‐hydroxy‐3‐ methox‐ybenzaldehyde)4‐methylbenzene‐1,2‐diamine (3‐MOBdMBn) was synthesized. Complexation of this ligand with zinc(3‐MOBdMBn‐Zn) was performed, and the catalytic activity of the complex was evaluated. The polymer‐supported analog of this complex(P‐3‐MOBdMBn‐Zn) was synthesized, and its catalytic activity was studied. These free and polymer‐anchored zinc complexes were prepared by the reactions of metal solutions with one molar equivalent of unsupported 3‐MOBdMBn or P‐3‐MOBdMBn in methanol under nitrogen. The catalytic activity of 3‐MOBdMBn‐Zn and P‐3‐MOBdMBn‐Zn was evaluated in phenol oxidation. The activity of P‐3‐MOBdMBn‐Zn was signif‐icantly affected by the polymer support, and the rate of phenol conversion was around 50% for polystyrene‐supported 3‐MOBdMBn. The experimental results indicated that the reaction rate was affected by the polymer support, and the rate of phenol conversion was 1.64 μmol/(L·s) in the presence of polystyrene‐supported 3‐MOBdMBn.     

Identification of bioactive constituents from different fractions of stems of Cuscuta reflexa Roxb. using GC-MS

The GC-MS analysis of fractions of methanol extract of stem of Cuscuta reflexa (Family Convolvulaceae) was carried out using a THERMO TRACE 1300 Gas Chromatograph equipped and coupled to a mass detector THERMO TSQ 8000 spectrometer with an TG 5MS (30 m × 0.25 mm, 0.25 μm) of capillary column. Database of National Institute of Standards and Technology (NIST) library was used to identify the components. GC-MS revealed two known compounds i.e. 2-Methoxy-4-vinyl phenol (6.80%) and Benzofuran-2,3-dihydro (20.89%) and other 12 unknown compounds such as 3,5-di-tert-Butyl-4-hydroxyanisole (35.50%); Hexatriacontane (12.02%); n-Hexadecanoic acid (10.12%); Scoparone (7.97%); Hexadecanoic acid methyl ester (5.22%); 1,3-Benzenediamine, N, N, N′, N′ tetramethyl- (15.43%); Phenol, 4(3-hydroxy1propenyl), 2-methoxy (9.31%); Phenol, 2,4 bis (1,1dimethylethyl); 2,3,5,6-Tetramethyl para phenylene diamine (14.18%); Retinoic acid-5,6-epoxy-5,6-dihydro (20.46%); 2,4-Dihydroxy-2,5-dimethyl-3(2H)furan-3-one (10.13%); 2,3-dihydro-3,5-dihydroxy-6-methyl-2-Propyl-tetrahydro-pyran-3-ol (10.13%); Pregn-4-ene-18-oic acid (5.75%) as some of the major compounds in its different fractions. Retinoic acid-5,6-epoxy-5,6-dihydro found as major compound may be responsible for blood glucose lowering potency.     

The effects of configuration mixing on excited charmonium decays

Configuration mixing betwenn ψ, ψ′ and ψ″ is considered in two models. In one model the confining potential consists of a scalar and a vector part; in the other model the vector confining potential interacts with a colour anomalous magnetic moment. It is shown that strong configuration mixing affects theEl transition rate and electronic decay widths of the vector mesons considerably.     

Infinite sequence of nonlocal conserved currents in a supersymmetric Grassmannian model

An infinite sequence of nonlocal conserved currents is constructed for the supersymmetric generalization of the U(N)/U(N-p) U(p) chiral model. The generating function for nonlocal charges is explicitly obtained in terms of the component fields.     

Solid phase oxidation of arsenite and the effect of gamma radiation

The oxidation of solid arsenite by bromate, chlorate and perchlorate ions has been studied at different temperatures and at a constant composition of 12. Arsenite is completely oxidized to arsenate. The fraction oxidized // — time /t/ data are reproducible. The rate of oxidation increases with an increase in temperature. Gamma radiation has no significant effect on the temperature independence of the oxidation process of this particular composition, although delayed oxidation appears with irradiated systems. The kinetics of oxidation process follows the conventional first order. The activation energies for the oxidation of As/III/ to As/V/ are 30.5, 44.0 and 67.9 kJ mol^–1, respectively, for bromate, chlorate and perchlorate systems, and for irradiated 29.8 and 67.3 kJ mol^–1, respectively, for bromate and perchlorate systems.     

New bounds for the total cross-section and the zero-free radius of the scattering amplitude

The upper bound on σ_T(s) is deduced which seems to be an improvement over the existing ones if one supplements it with the behaviour of the slope parameter data. Bound on the zero-free radius of the scattering amplitude is also obtained.     

Flavour-changing neutral currents in models with extra<Emphasis Type="Italic">Z′</Emphasis> boson

New neutral gauge bosonsZ′ are the features of many models addressing the physics beyond the standard model. Together with the existence of new neutral gauge bosons, models based on extended gauge groups (rank > 4) often predict new charged fermions also. A mixing of the known fermions with new states, with exotic weak-isospin assignments (left-handed singlets and right-handed doublets) will induce tree-level flavour-changing neutral interactions mediated byZ exchange, while if the mixing is only with new states with ordinary weak-isospin assignments, the flavour-changing neutral currents are mainly due to the exchange of the new neutral gauge bosonZ′. We review flavour-changing neutral currents in models with extraZ′ boson. Then we discuss some flavour-changing processes forbidden in the standard model and new contributions to standard model processes.