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61.
Heavy gauge bosons such as W' are expected to exist in many extensions of the Standard Model. In this paper, the most general Lagrangian for the interaction of W' with top and bottom quarks is considered. This Lagrangian consists of V- A and V + A structure with in general complex couplings. Such interactions produce an Electric Dipole Moment (EDM) for the top quark at one loop level. We predict the allowed ranges for the mass and couplings of W' by using the upper limit on the top quark EDM. 相似文献
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This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS–ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC–MS. The limits of detection under optimized conditions range from 0.5 to 10 ng.L?1. The intra– and inter–day relative standard deviations (RSDs) (for n?=?10, 5 respectively) using a single fiber are 6–10 and 10–15%, respectively. The fiber–to–fiber RSDs (for n?=?3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%.
相似文献
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Humenny WJ Mitzinger S Khadka CB Najafabadi BK Vieira I Corrigan JF 《Dalton transactions (Cambridge, England : 2003)》2012,41(15):4413-4422
The ligation of a N-heterocyclic carbene (NHC) to group 11 metal salts (Cu, Ag) was explored as an alternative to PR(3) ligands for the formation of copper- and silver-chalcogenolate cluster complexes. AgOAc and CuCl salts ligate with the NHC 1,3-di-isopropylbenzimidazole-2-ylidene ((i)Pr(2)-bimy) forming [Ag(OAc)((i)Pr(2)-bimy)] 1, [Ag(OAc)((i)Pr(2)-bimy)(2)] 2, [CuCl((i)Pr(2)-bimy)](2)3 and [CuCl((i)Pr(2)-bimy)(2)] 4 depending on the ratio of ligand to metal used. These have been characterized via spectroscopic and crystallographic methods. Complexes 1 and 3 were reacted with S(Ph)SiMe(3) and Se(Ph)SiMe(3) to form the polynuclear metal-chalcogenolates [Ag(4)(μ-EPh)(4)((i)Pr(2)-bimy)(4)] (5, E = S; 6, E = Se) and [Cu(3)(μ-EPh)(3)((i)Pr(2)-bimy)(3)] (7, E = S; 8, E = Se) in good yields. The structures of 5-8, as determined by single crystal X-ray crystallography, are described. 相似文献
67.
As one of the most recently developed membrane separation processes, nanofiltration (NF) has found a number of industrial applications. Ceramic NF membranes are also regarded as the appropriate choice in many applications, due to their higher chemical and physical stability. In this study, the rejection of the chloride ion is investigated using bi-layered γ-Al2O3-TiO2 NF membranes based on α-alumina supports. Compression is used in preparation of the supports and sol-gel dip-coating for the top-layer formation. SEM micrographs, XRD, and nitrogen adsorption/desorption isotherms are used for membrane characterisation. The results show that the calcination temperature (600°C) results in different crystal structures including the brookite phase of TiO2, the γ phase of Al2O3, and a combined phase of aluminium-titanium oxides. The average pore size of the membrane was identified as 1.6 nm using an adsorption/desorption isotherm. The rejection was also studied for the chloride ion, using a cross-flow filtration module. Filtration tests were carried out under different pressures, pH values, and salt concentrations; these showed a smoother behaviour particularly around the isoelectric points (IEPs) due to the dual-layer structure, with the best rejection at pH of approximately 5. 相似文献
68.
Statistical models for the study of solvent effects on the endo/exo selectivity of Diels-Alder reactions using molecular surface electrostatic potentials was obtained. The models show that hydrogen bond interactions of solvent molecules favor the predominance of the endo isomer for the reaction of methyl acrylate, methyl methacrylate and methyl trans-crotonate with cyclopentadiene whereas the effect of solvophobicity seems to be negligible. 相似文献
69.
An optical chemical sensor based on 2-mercaptopyrimidine (2-MP) in plasticized poly(vinyl chloride) (PVC) membrane incorporating
(N,N-diethyl-5-(octadecanoylimino)-5H benzo[a]phenoxazine-9-amine (ETH 5294) and sodium tetraphenyl borate (NaTPB) for batch and
flow-through determination of mercury ion is described. The response of the sensor is based on selective complexation of Hg2+ with 2-MP in the membrane phase, resulting in an ion exchange process between H+ in the membrane and Hg2+ in the sample solution. The influences of several experimental parameters, such as membrane composition, pH, and type and
concentration of the regenerating reagent, were investigated. The sensor has a response range of 2.0 × 10−9 to 2.0 × 10−5 mol L−1 Hg2+ with a detection limit of 4.0 × 10−10 mol L−1 and a response time of ≤45 s at optimum pH of 6.5 with high measurement repeatability and sensor-to-sensor reproducibility.
It shows high selectivity for Hg2+ over several transition metal ions, including Ag+, Cd2+, Co2+, Cr3+, Cu2+, Fe3+, Mn2+, Ni2+, and common alkali and alkaline earth ions such as Na+, K+, Mg2+, Ca2+, and Pb2+. The sensor membrane can be easily regenerated with dilute acid solutions. The sensor has been used for the determination
of mercury ion concentration in water samples. 相似文献
70.