Cabibbo angle,CP violation and quark masses

By adding suitable discrete flavor symmetries to SU(2)_L ? SU(2)_R ? U(1) left-right symmetric gauge models of weak and electromagnetic interactions, we are able to express all the mixing angles between the quark flavors (u, d, s,c) in terms of the quark masses. This enables us to compute the Cabibbo angle and the CP violating phases using plausible values for the quark masses. The CP violating K ar 2π decay amplitude η_+? (and η₀₀ in the model is then given purely in terms of the parity violating parameter of the model (m_WL⁺/m_WR⁺)².     

The Electrical Resistivity of Metals at High Temperatures. An Analysis for Alkali and Noble Metals

Experimental data for the electrical resistivity of K, Na, Cu, Ag and Au at high temperatures and constant volume have been analysed. In particular, corrections to the most simple theoretical model (often referred to as Ziman's model) arising from lattice anharmonicity, Debye-Waller factors, multi-phonon scattering and terms beyond the Born approximation are discussed. The net effect of all these corrections amounts at most to some 10% decrease in the resistivity close to the melting point.     

Transition metal complexes with thio­semicarbazide‐based ligands. XV. A square‐pyramidal NiII complex with an asymmetric coordination of 2,6‐di­acetyl­pyridine bis(S‐methyl­iso­thio­semicarbazone)

The title compound, [di­acetyl­pyridine bis(S‐methyl­iso­thio­semicarbazonato)]­iodo­nickel(II), [Ni(C₁₃H₁₈N₇S₂)I], is the first example of a complex involving the ²N coordination of the iso­thio­semicarbazide moiety. 2,6‐Di­acetyl­pyridine bis(S‐methyl­iso­thio­semicarbazone), as a potentially pentadentate ligand (N₅), is coordinated as a tetradentate species, whereby one (deprotonated) iso­thio­semicarbazide moiety is coordinated in the usual way (¹N⁴N), but the other (neutral) is bonded via the ²N atom only, the fourth ligator being the pyridine nitro­gen. The difference in coordination mode of the iso­thio­semicarbazide moiety is reflected in the ¹N—²N bond lengths of 1.359 (4) and 1.379 (3) Å in the deprotonated and undeprotonated moieties, respectively. The structure contains three fused chelate rings in a 5:5:6 arrangement. The six‐membered ring has a non‐planar conformation.     

Theoretical study on the mechanism and kinetics of addition of hydroxyl radicals to fluorobenzene

Geometries, frequencies, reaction barriers, and reaction rates were calculated for the addition of OH radical to fluorobenzene using Möller–Plesset second‐order perturbation (MP2) and G3 methods. Four stationary points were found along each reaction path: reactants, prereaction complex, transition state, and product. A potential for association of OH radical and fluorobenzene into prereaction complex was calculated, and the associated transition state was determined for the first time. G3 calculations give higher reaction barriers than MP2, but also a significantly deeper prereaction complex minimum. The rate constants, calculated with Rice–Ramsperger–Kassel–Marcus (RRKM) theory using G3 energies, are much faster and in much better agreement with the experiment than those calculated with MP2 method, as the deeper well favors the formation of prereaction complex and also increases the final relative populations of adducts. The discrepancies between the experimental and calculated rate constants are attributed to the errors in calculated frequencies as well as to the overestimated G3 reaction barriers and underestimated prereaction complex well depth. It was possible to rectify those errors and to reproduce the experimental reaction rates in the temperature range 230–310 K by treating the relative translation of OH radical and fluorobenzene as a two‐dimensional particle‐in‐the‐box approximation and by downshifting the prereaction complex well and reaction barriers by 0.7 kcal mol^?1. The isomeric distribution of fluorohydroxycyclohexadienyl radicals is calculated from the reaction rates to be 30.9% ortho, 22.6% meta, 38.4% para, and 8.3% ipso. These results are in agreement with experiment that also shows dominance of ortho and para channels. © 2012 Wiley Periodicals, Inc.     

Inactivation of cholinesterases by silver and gold ions in vitro

The main goal of the present study was to investigate the effects of silver and gold ions on cholinesterases (ChEs) activity due to increasing application of these metals in a wide variety of nanomaterials. A chromogenic assay using the substrate o-nitrophenyl acetate/butyrate made it possible to conclude unmistakably that both metals inhibit ChEs. Addition of bovine serum albumin (BSA) indicates that binding of metal ions to albumin could serve to scavenge metals and consequently reduce their amount for reaction with ChEs. The effects of metal ions on ChE should be taken into consideration when using this enzyme as an environmental biomarker.      

(E)‐4‐[(2‐Carbamoylhydrazinylidene)methyl]‐3‐hydroxy‐5‐hydroxymethyl‐2‐methylpyridin‐1‐ium nitrate

The title compound, C₉H₁₃N₄O₃⁺·NO₃⁻, is the first structurally characterized Schiff base derived from semicarbazide and pyridoxal. Unusually for an unsubstituted semicarbazone, the compound adopts a syn conformation, in which the carbonyl O atom is in a cis disposition relative to the azomethine N atom. This arrangement is supported by a pair of hydrogen bonds between the organic cation and the nitrate anion. The cation is essentially planar, with only a hydroxymethyl O atom deviating significantly from the mean plane of the remaining atoms (r.m.s. deviation of the remaining non‐H atoms = 0.01 Å). The molecules are linked into flat layers by N—H...O and C—H...O hydrogen bonds. O—H...O hydrogen bonds involving the hydroxymethyl group as a donor interconnect the layers into a three‐dimensional structure.