Adsorption of sarin and chlorosarin onto the Al12N12 and Al12P12 nanoclusters: DFT and TDDFT calculations

This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al₁₂N₁₂ and Al₁₂P₁₂ nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al³⁺ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al₁₂N₁₂ nanocluster are larger than these values for the Al₁₂P₁₂ nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al₁₂N₁₂ nanocluster.     

Thin‐layer chromatography—an image‐processing method for the determination of acidic catecholamine metabolites

A sensitive and convenient method for acidic catecholamine metabolites (including homovanillic acid, vanillylmandelic acid, 3,4‐dihydroxymandelic acid, and 3,4‐dihydroxyphenylacetic acid) determination was developed based on thin‐layer chromatography and image‐processing analysis. The metabolites were separated without a prederivatization step using reversed phase RP‐18W high‐performance plates. The mobile phase composition, detection, and quantification conditions were systematically investigated through several trials. The reaction with 2,2‐diphenyl‐1‐picrylhydrazyl radical allowed specific detection of acidic catecholamine metabolites with a high sensitivity and a wide linear range. The limit of detection and the limit of quantification were in the range of 13–103 and 18–120 ng/spot, respectively, in all cases. Mean recoveries determined were in the range 95–106% for all of the investigated compounds. The proposed method allowed rapid simultaneous determination of acidic catecholamine metabolites from spiked human urine sample.     

基于改进的径向基函数神经网络的铁磁谐振系统混沌控制

面向中性点直接接地电力系统发生的铁磁谐振过电压所显现的混沌特性，在径向基函数神经网络的基础上，提出引进一种极大熵学习算法对该混沌系统进行控制.该方法通过最优化一个目标函数导出中心向量的学习规则，充分利用网络隐层的聚类功能，极大改善网络的回归和学习能力.对具体的铁磁谐振系统的数值实验证实了该方法在针对铁磁谐振过电压混沌控制中的有效性和可行性. 关键词： 中性点直接接地系统 混沌控制 径向基函数 极大熵原理     

Submicron wires with nanosized grain structure

Recent results have shown that size-effects in nanostructured materials may enable much more efficient thermoelectric devices. In this paper, the electrochemical preparation of Bi_1.95Te_2.7Se_0.35 and Bi_2.15Te_2.55Se_0.3 submicron wires arrays with nanosized grain structure is reported. X-ray diffraction (XRD) analysis has indicated the presence of nanosized crystallites in the structure of the wires; high resolution transmission electron microscopy (HRTEM) investigations have confirmed the formation of crystallites with geometrical dimensions of 5–14 nm and random orientations in the structure of these wires. These wires were further analyzed by field emission scanning electron microscopy (FESEM). The measurement of the transport properties showed that a highly degenerate semiconductor with a large thermopower (−125 μV K⁻¹ at 300 K) and a low resistivity was obtained.     

Synthesis of corrected multi-wavelength spectrometers for atmospheric trace gases

The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possible structures of corrected spectrometers is considered. The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere. For experimental checkup of achieved theoretical results, a laboratory pattern of three-wavelength spectrome- ter is developed and tested.     

The salt–cocrystal spectrum in salicylic acid–adenine: the influence of crystal structure on proton‐transfer balance

At one extreme of the proton‐transfer spectrum in cocrystals, proton transfer is absent, whilst at the opposite extreme, in salts, the proton‐transfer process is complete. However, for acid–base pairs with a small ΔpK_a (pK_a of base ? pK_a of acid), prediction of the extent of proton transfer is not possible as there is a continuum between the salt and cocrystal ends. In this context, we attempt to illustrate that in these systems, in addition to ΔpK_a, the crystalline environment could change the extent of proton transfer. To this end, two compounds of salicylic acid (SaH) and adenine (Ad) have been prepared. Despite the same small ΔpK_a value (≈1.2), different ionization states are found. Both crystals, namely adeninium salicylate monohydrate, C₅H₆N₅⁺·C₇H₅O₃^?·H₂O, I , and adeninium salicylate–adenine–salicylic acid–water (1/2/1/2), C₅H₆N₅⁺·C₇H₅O₃^?·2C₅H₅N₅·C₇H₆O₃·2H₂O, II , have been characterized by single‐crystal X‐ray diffraction, IR spectroscopy and elemental analysis (C, H and N) techniques. In addition, the intermolecular hydrogen‐bonding interactions of compounds I and II have been investigated and quantified in detail on the basis of Hirshfeld surface analysis and fingerprint plots. Throughout the study, we use crystal engineering, which is based on modifications of the intermolecular interactions, thus offering a more comprehensive screening of the salt–cocrystal continuum in comparison with pure pK_a analysis.     

MRS signal quantitation: a review of time- and frequency-domain methods

In this paper an overview of time-domain and frequency-domain quantitation methods is given. Advantages and drawbacks of these two families of quantitation methods are discussed. An overview of preprocessing methods, such as lineshape correction methods or unwanted component removal methods, is also given. The choice of the quantitation method depends on the data under investigation and the pursued objectives.     

Biocompatible and bioactive coatings of Mn-doped β-tricalcium phosphate synthesized by pulsed laser deposition

The extension of pulsed laser deposition to the synthesis on Ti substrates of β-tricalcium phosphate (β-TCP) coatings doped with manganese is reported. Targets sintered from two crystalline Mn-doped β-TCP powders (with the composition Ca_2.9Mn_0.1(PO₄)₂ and Ca_2.8Mn_0.2(PO₄)₂) were ablated with an UV KrF* (λ = 248 nm, τ ∼ 7 ns) laser source. X-ray diffraction and energy dispersive X-ray spectroscopy investigations showed that the films, while prevalently amorphous, had a Ca/P ratio of about 1.50-1.52. Scanning electron microscopy analyses revealed a rather homogeneous aspect of the coatings which were molded to the relief of the chemically etched Ti substrate. Fluorescence microscopy was applied to test the proliferation of mesenchymal stem cells grown on the obtained biostructures. Our investigations found that, even 14 days after cultivation, the synthesized films were not cytotoxic. On the contrary, they showed excellent bioactivity, as demonstrated by the neat spread of the cells over the entire surface of Mn-doped β-TCP. When tested in osteoprogenitor cell culture, the Ca_2.8Mn_0.2(PO₄)₂ samples revealed a higher potential for proliferation and better viability compared with Ca_2.9Mn_0.1(PO₄)₂.     

Software for the Computation of Detection Efficiency and of Coincidence Summing Effects Including Neutron Self-Shielding

The GESPECOR software, initially developed for the computation of efficiency of HPGe detectors in environmental -ray spectrometry, was applied to NAA. The software is useful for the computation of efficiency and of self-attenuation and coincidence-summing corrections for common experimental conditions. A new source subroutine was implemented in GESPECOR for solving the more complex case of non-uniform sources. In this way neutron self-shielding in the activation of samples of large volume is taken into account. The dependence of the detection efficiency on the flux distribution is discussed.     

Verteilung und Valenz der Kationen in Spinellsystemen mit Eisen und Chrom. III. Gitterkonstanten,Mößbauer-Spektren und Thermokraft der Mischkristalle ZnFeCrO4?Fe2CrO4

Distribution and Valence of the Cations in Spinel Systems with Iron and Chromium. III. Lattice Constants, Mössbauer Spectra, and Seebeck Coefficients of the Solid Solution ZnFeCrO₄? Fe₂CrO₄ For the spinel system Zn_1–x²⁺Fe_x–λ²⁺Fe_λ³⁺(Fe_λ²⁺ · Fe_1?λ³⁺ Cr³⁺)O₄ λ has been determined by lattice constants and ionic distances: λ = 0 in the region 0 ? x ? 0.3; in the region 0.3 < x ? 1 λ increases linearly to 0.44. Mössbauer spectra between x = 0 and x = 0.6 confirm this distribution. All spinels are n-type hopping conductors mainly conducting on the octahedral sites.