Base Hydrolysis and Use of Cationic Ammonium Dyes in Which the Chromophore System Is not Conjugated with the Nitrogen Atom

The capability of cationic dyes in which the onium group is not conjugated with the chromophore system to form aqueous dispersions in a weakly alkaline medium was examined. Such dyes can be fixed on a fiber in increased amounts owing to their binding not only in the cationic form but also in the hydrolyzed monomolecular form.     

Thermodynamics and kinetics of initial gas phase reactions in chemical vapor deposition of titanium nitride. Theoretical study of TiCl4 ammonolysis

Thermodynamic equilibrium and kinetics of the gas‐phase reaction between TiCl₄ and NH₃ have been studied computationally using results from recent quantum mechanical calculations of titanium tetrachloride ammonolysis. 1 These calculations were based upon the transition state theory for the direct reactions and RRKM theory for the reactions proceeding via intermediate complex. Rate constants for the barrierless reactions were expressed through the thermodynamic characteristics of the reagents and products using a semiempirical variational method. The kinetic simulation of the gas‐phase steps of CVD was performed within a model of a well‐stirred reactor at temperatures 300–1200 K and residence times between 0.1–2 s. At temperatures below 450 K formation of donor–acceptor complexes between TiCl₄ and NH₃ is the dominating process. At higher temperatures sequential direct ammonolysis takes place. At typical LPCVD conditions the only product of the first step of ammonolysis, TiCl₃NH₂, is formed in substantial amount. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1366–1376, 2001     

Experimental and Theoretical Study of the Atomic Structure Evolution of High-Entropy Alloys Based on Fe,Cr, Ni,Mn, and Co upon Thermal and Radiation Aging

Physics of the Solid State - A comprehensive experimental–theoretical study of the processes of local ordering of multicomponent alloys has been carried out. Atom probe tomography and...     

Self-organization and morphological characteristics of selenium-containing nanostructures based on rigid-chain polymers

Macroinitiators containing β-diketonate fragments were prepared by copolymerization of styrene with cobalt(II) 5-Formation and morphological characteristics of selenium-containing nanostructures formed by reduction of selenious acid with ascorbic acid in the presence of ionic or nonionic polymeric stabilizer in aqueous solutions were studied by methods of nonlinear optics and flow birefringence at widely varied selenium to polymer weight ratio in solution ν. The molecular weights, root-mean-square and hydrodynamic sizes, and mean density of the nanostructures were calculated, and the trends in variation of these quantities were compared.     

Synthesis and study of yttrium aluminum garnets doped with neodymium and ytterbium

Ytterbium- and neodymium-substituted yttrium aluminum garnets were obtained by hydroxide coprecipitation and by the cryochemical method. A continuous series of solid solutions in the Y₃Al₅O₁₂ — Yb₃Al₅O₁₂ system and limited solid solutions (Nd _x Y_{1 ? x} )₃Al₅O₁₂ (0 ≤ x ≤ 0.19) were obtained. The synthetic methods used made it possible to reduce the synthesis temperature from 1800 to 950°C and to obtain more homogeneous and nanosized material.     

Morphological characteristics of selenium-containing nanostructures based on rigid-chain molecules

Selenium-containing nanostructures of rigid-chain polymers with close molecular masses were studied by flow birefringence (FB) and static and dynamic light scattering at a fixed selenium to polymer mass ratio ν = 0.1 in solution. The group of polymers under study included the cationic polyelectrolyte poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate, anionic polyelectrolyte carboxymethylcellulose, and nonionogen polymer oxyethylcellulose. High-molecular selenium-containing polymer nanostructures were found in all cases. Nanostructures with a maximum molecular mass and the largest number of constituent macromolecules were obtained using oxyethylcellulose. At ν = 0.1 the mean square radii of inertia of the nanostructures were almost independent of the nature of the polymer matrix. The thermodynamic state of the solutions of nanostructures was close to the ideal one in all cases. For the region where stable dispersions formed, the Gibbs energies of macromolecule-selenium nanoparticle interactions were calculated and shown to be almost independent of the nature of the polymer matrix at ν = 0.1. The close mean square radii of inertia R _g^* of the nanostructures, the Gibbs energies of interaction, and the equivalence of the thermodynamic state of the solutions of nanostructures obtained for all polymer matrices at ν = 0.1 suggest that ν = 0.1 corresponds to the ultimate adsorption capacity of selenium nanoparticles; the considerable differences between the molecular masses (for close R _g ^* values), mean densities, and structural conformation parameters ρ* point to different packings of macromolecules in the nanostructures under study.     

Limits on charge carrier mobility in suspended graphene due to flexural phonons

The temperature dependence of the mobility in suspended graphene samples is investigated. In clean samples, flexural phonons become the leading scattering mechanism at temperature T?10 K, and the resistivity increases quadratically with T. Flexural phonons limit the intrinsic mobility down to a few m(2)/V s at room T. Their effect can be eliminated by applying strain or placing graphene on a substrate.     

Tetrazoles: LVII. Preparation and chemical properties of 1-substituted 5-arylsulfonyltetrazoles

Oxidation of 1-substituted 5-arylsulfanyltetrazoles with m-chloroperoxybenzoic acid and NaIO₄ in the presence of RuCl₃ leads to the formation of the 5-arylsulfonyltetrazoles. The microwave activation significantly accelerates the oxidation with sodium periodate. The phenylsulfonyl group in compounds obtained underwent the nucleophilic substitution when treated with ethanol, phenol, or benzimidazole in acetonitrile in the presence of NaOH.