The 13C NMR spectra of π-arenechromium carbonyl complexes

The ¹³C NMR spectra of π-arenechromium complexes XC₆H₅Cr(CO)₂L (where I, L  CO; II, L  PPh₃; X  aliphatic and aromatic substituents) were investigated. The effect of the nature of the substituent X on the chemical shifts of the carbon atoms of the aromatic ring in these complexes was analyzed.It was established that a correlation exists between δ(¹³C) and σ_R (Taft's constant) in complexes I, not only for C(4) nuclei but also for C(3) metal atoms, the difference being that the slopes of the corresponding curves are opposite.     

A new reaction of fluorodinitromethyl group

A general reaction of the transformation of the fluorodinitromethyl group into the fluoronitromethyl group by denitration upon treatment with Na₂SO₃ or KI in aqueous formaldehyde was found. A preparative method for synthesizing fluoronitroalcohols was developed on the basis of this reaction.     

Size and Shape Effects in Optical Spectra of Silver and Gold Nanoparticles

Journal of Russian Laser Research - We report some theoretical results on the extinction, absorption, and scattering of light by individual silver and gold nanoparticles of different sizes and...     

Synthesis of 2-amino-5,5-dialkyl-4-arylmethylidene-2-oxazolines from 2-alkyl-4-arylbut-3-yn-2-ols and guanidine

Reaction between 2-alkyl-4-arylbut-3-yn-2-ols and guanidine in refluxing pyridine affords 2-amino-5,5-dialkyl-4-arylmethylidene-2-oxazolines.     

Acoustic-wave reflection from a gas−droplet–mixture boundary

The problem on acoustic-wave reflection from the boundary of a gas?droplet mixture is considered. For the interface between the pure gas and the gas?droplet mixture at a wave inclined incidence, a nonmonotonic dependence of the reflectance on the volume content of droplets is established. The values of the critical wave-incidence angle and the volume content of inclusions at which the reflectance vanishes are found and illustrated. The possibility of occurrence of the lowest reflectance in dependence on the frequency of perturbations in a certain interval of the wave-incidence angle related mainly to the difference in the densities of the gas-droplet mixture and the pure gas is shown.     

Optimization of geometry of elastic bodies in the vicinity of singular points on the example of an adhesive lap joint

The stress state in adhesive lap joints with various geometric shapes of spew fillet is studied. It is noted that the applied design models of the considered problem include singular points at which infinite stress values are possible if one uses the linear elasticity theory to calculate the stress state. Based on the conclusions of the solution of the geometry optimization problem in the vicinity of the singular points of elastic bodies, variants of the geometry of spew fillet, which provide the most significant decrease in the concentration of stresses in adhesive lap joints, are proposed.     

Allobetulin Ring A Contraction Effected by Sulfur Diethylaminotrifluoride

Russian Journal of General Chemistry - The action of sulfur diethylaminotrifluoride on 19β,28-epoxyoleanan-3-ol (allobetulin) causes dehydration of the terpenoid and isomerization of the ring...     

On Estimation of Temperature Uncertainty Using the Second Order Adjoint Problem

The uncertainty of temperature prediction from the heat flux error is estimated using first and second order adjoint equations. The adjoint codes developed for the inverse heat transfer problems provide the uncertainty estimation for the corresponding forward problems. Numerical tests corroborate the feasibility of fast uncertainty estimation using Hessian maximum eigenvalue obtained via second order adjoint equations.     

Synthesis of Copper Nanoparticles by Thermal Decomposition of Anhydrous Copper Formate

Highly dispersed anhydrous copper formate obtained by cryochemical synthesis is subjected to thermal decomposition in an atmosphere of hydrogen. X-ray diffraction, PAM, UV-spectroscopy, and lowtemperature adsorption of argon show that the obtained powder contains only copper nanoparticles with a size of 50–200 nm.