No abstract available

[en] The structure of 5-formyltetrahydrofolate cyclo-ligase from B. anthracis determined by X-ray crystallography at a resolution of 1.6 Å is described. Bacillus anthracis is a spore-forming bacterium and the causative agent of the disease anthrax. The Oxford Protein Production Facility has been targeting proteins from B. anthracis in order to develop high-throughput technologies within the Structural Proteomics in Europe project. As part of this work, the structure of 5-formyltetrahydrofolate cyclo-ligase (BA4489) has been determined by X-ray crystallography to 1.6 Å resolution. The structure, solved in complex with magnesium-ion-bound ADP and phosphate, gives a detailed picture of the proposed catalytic mechanism of the enzyme. Chemical differences from other cyclo-ligase structures close to the active site that could be exploited to design specific inhibitors are also highlighted

[en] Mg metal has been used as an anode material for Mg-ion rechargeable batteries (MRBs), but the undesired passivation layer between Mg and electrolyte indeed limits the further development of MRBs. Replacing Mg with Sn and Mg₂Sn has been proved to be an alternative for Mg ions storage based on the alloying reaction between Mg and Sn. In the present study, we have investigated the electrochemical performance of hypoeutectic Mg-Sn alloy anodes with an all-phenyl complex (APC) electrolyte. The microstructure and electrochemical results indicate that the Mg14Sn alloy anode displays different electrochemical behaviors of Mg stripping/plating due to the formation of eutectic (α-Mg+Mg₂Sn) phase. Special anodic peaks, different reaction sites and high overpotential are observed in the Mg14Sn alloy anode. Electrochemical impedance spectroscopy (EIS) results show that the anode-electrolyte interface is significantly affected by the addition of Sn. Mg14Sn alloy anode shows much lower resistance than pure Mg after 30 cycles. The results obtained from electron microscopic observations confirm that the formation of nanosized β-Sn stems from the eutectic phase.

[en] In this paper we present the results of the variation of secondary Mg⁺ ion yield as a function of Cd⁺ ion current, focussed on the Mg target, at different fixed values of bombarding ion energies. We then try to explain qualitatively the phenomena observed and formulate underlying mechanism. (orig./RK)

[en] The synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives in the presence of alkaline earth metal chlorides was reported. Specifically, the MgCl₂ catalyzed the synthesis of 1,4-DHP derivatives in good yields, ranging from 69 - 87 %. The Mg²⁺ serves as the Lewis acid catalyst in the formation of 1,4-DHP and the proposed mechanism of the formation of 1,4-DHP was elaborated in this manuscript. There are many advantages employing MgCl₂ as a catalyst in this study, including inexpensive, ubiquitous availability of this metal, simple filtration protocol, which has spark considerable interest in the use of this catalyst in promoting organic reactions. (author)

[en] Two calcium binding sites, separated by about 9.3 A, present in the loops that connect the β-sheets of N-terminal domain contain the ligating residues F14, A15, G16, D79, and D18, D19, L76, respectively. Magnesium is found to bind in regions, which are marginally different owing to the disparity in the ionic radii of Ca²⁺ and Mg²⁺. The entropy analysis on the loops of 5-lipoxygenase, implementing the wormlike chain model, explains that the N-terminal β-barrel is well suited to accommodate calcium binding sites. The large buried side chain area of W102 (compared to W13 and W75) and comparatively smaller fraction of side chain exposed to polar atoms corroborate the calcium induced higher affinity to phosphatidylcholine (PC). However, W80 lying in close proximity of the calcium binding sites is expected to have considerable PC affinity but negligible calcium induced effect on PC binding

No abstract available

[en] Evaluation of lattice displacement in Mg-ion implanted GaN is studied by combining elastic recoil detection analysis (ERDA), Rutherford backscattering spectroscopy (RBS) and Photoluminescence (PL) measurements. Mg-ion implantation into GaN single crystal wafer is performed with energies of 30 keV (ion fluence; 3.5 × 10¹⁴ cm⁻²) and 60 keV (6.5 × 10¹⁴ cm⁻²) at room temperature. The ERDA measurements using the 1.5 MeV helium beam can evaluate hydrogen from the surface to ∼300 nm. The hydrogen concentration for un-implanted and as-implanted GaN is 3.1 × 10¹⁴ cm⁻² and 6.1 × 10¹⁴ cm⁻² at around 265 nm in depth. χ_min (the ratio of aligned and random yields) near the surface of the 〈0 0 0 1〉 direction for Ga is 1.61% for un-implanted and 2.51% for Mg-ion implanted samples. On the other hand, the value of χ_min for N is 10.08% for un-implanted and 11.20% for Mg-ion implanted samples. The displacement concentration of Ga and N estimated from these χ_min values is 4.01 × 10²⁰ cm⁻³ and 5.46 × 10²⁰ cm⁻³, respectively. This suggests that Ga vacancy (V_Ga), N vacancy (V_N), Ga interstitial (Ga_i), and N interstitial (N_i) is introduced in Mg-ion implanted GaN. A strong emission at around 400 nm in as-implanted GaN is related to a V_N donor and some acceptor pairs. It is suggested that the origin of the very high resistivity after the Mg-ion implantation is attributed to the carrier compensation effect due to the deep level of N_i as a non-radiative center.

[en] From observations of interstellar Mg I, II resonance lines, Gurzadyan has proposed recently that for the majority of hot stars most of the line-of-sight gas originates in dense, circumstellar clouds. To support this conclusion, which is contrary to most current models of the interstellar gas, he has set out apparently strong theoretical arguments based on empirical evidence from the sample of stars considered. In this paper we have considered the same data and have included some additional observations of interstellar Mg lines. We suggest that an empirical relationship between Mg II equivalent width and stellar effective temperature, which is central to the model proposed by Gurzadyan, may be explained by an observational selection effect. Further, we suggest that while circumstellar material may well contribute in part to observed column densities, there is no firm evidence that most of the gas is located in circumstellar clouds. (orig.)

[en] In various spectral regions the intensity variations are studied along the track of a base meteor with three flares having the character of spherical explosion. The concentration of radiating atoms in the flare is estimated. In the moment of the first flare there was a sharp intensity increase in the red region of spectrum. In two other flares the radiation in the interval 4400-4700 A is predominated. During all the three flares which continued 0.04 s, the meteoric body lost 40% of its initial mass. The concentration of Mg 2 atoms (4481 A) which gave the main contribution into the intensity of the third, brightest flare in blue spectral region, is found to be 1x10¹¹ cm^-3