Temperature Dependence of the Refractive Indices of Doped K2SO4 Crystals

Journal of Applied Spectroscopy - The temperature dependence of the refractive indices of K2SO4 with copper impurity was investigated. It was found that introduction of the copper impurity leads to...     

Novel halogenated cyclopentasilylene-2,4-dienes via DFT

In view of immense importance of silylenes and the fact that their properties undergo significant changes on substitution with halogens, here, we have used B3LYP/6-311++G** level of theory to access the effects of 1–4 halogens (X = F, Cl, Br, and I) on four unprecedented sets of cyclopentasilylene-2,4-dienes; with the following formulas: SiC₄H₃X ( 1 _X ), SiC₄H₂X₂ ( 2 _X ), SiC₄HX₃ ( 3 _X ), and SiC₄X₄ ( 4 _X ). In going down from F to I, the singlet (s)-triplet (t) energy gap (ΔE_s-t, a possible indication of stability), and band gap (ΔE_H-L) decrease while nucleophilicity (N), chemical potential (μ), and proton affinity (PA) increase. The overall order of N, μ, and PA for each X is 2 _X > 1 _X > 3 _X > 4 _X . Precedence of 2 _X over 1 _X is attributed to the symmetric cross conjugation in the former. The highest and lowest N are shown by 2 _I and 4 _F . The trend of divalent angle () for each X is 4 _X > 1 _X > 3 _X > 2 _X . The results show that in going from electron withdrawing groups (EWGs) to electron donating groups (EDGs), the ΔE_s-t and ΔE_H-L decrease while N, μ, and PA increase. Also, rather high N of our scrutinized silylenes may suggest new promising ligands in organometallic chemistry.     

<Emphasis Type="Italic">FCC/BCC</Emphasis> competition and enhancement of saturation magnetization in nanocrystalline Co-Ni-Fe films

The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B _s = 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed, which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of the composition. The text was submitted by the authors in English.     

Phase state stabilization of ammonium nitrate for creating an oxidizing agent for smokeless gas-generating formulations yielding no toxic combustion products

Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined.     

Scaling properties of fracture surfaces on glass strengthened by ionic exchange

In this work the results of the statistical topometric analysis of fracture surfaces of soda-lime-silica glass with and without ionic exchange treatment are reported. In this case, the mechanism of substitution is K⁺-Na⁺. atomic force microscopy (AFM) was employed to record the topometric data from the fracture surface. The roughness exponent (ζ) and the correlation length (ξ) were calculated by the variable bandwidth method. The analysis for both glasses (subjected and non-subjected to ionic exchange) for ζ shows a value ∼0.8, this value agrees well with that reported in the literature for rapid crack propagation in a variety of materials. The correlation length shows different values for each condition. These results, along with those of microhardness indentations suggest that the self-affine correlation length is influenced by the complex interactions of the stress field of microcracks with that resulting from the collective behavior of the point defects introduced by the strengthening mechanism of ionic exchange.     

Carbon adsorbents for the sorpting and concentrating nobel metals

Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic.     

Gas adsorption in mcm-41 porous silicas dynamic measurements using sans

The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron...     

Rigidity and flexibility of virtual polytopes

All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual polytope.