Gas-chromatographic headspace analysis: Metrological aspects

Various methods are studied for preparing stable gas mixtures with trace amounts of volatile substances based on a buffer effect of heterogeneous systems and implemented into headspace analysis, that is, static and dynamic versions of gas extraction. Information is provided on certified procedures for preparing such mixtures, that is, vapor-phase sources of gas mixtures included into the State Register of Measuring Instruments.     

A method to solve boundary-value problems of magnetoelasticity for flexible ring plates of variable stiffness

A method to solve boundary-value problems of magnetoelasticity for ring plates of variable stiffness is proposed. It is based on a geometrically nonlinear theory of the second order and employs, in a successive manner, the Newmark scheme, the quasi-linearization method, the method of lines, and the discrete-orthogonalization method     

Oxidation of 2,3,6-trimethylphenol on titanium dioxide xerogel by hydrogen peroxide in the absence of an organic solvent

Fundamental aspects of the synthesis of 2,3,5-trimethylbenzoquinone by oxidation of 2,3,6-trimethylphenol adsorbed on the surface of a titanium dioxide xerogel and on TiO₂ modified with powdered cellulose with hydrogen peroxide without any organic solvent involved in the process were studied.     

Physicochemical aspects of phosphorite powder decomposition by weak acid

Fundamental aspects of phosphorite powder decomposition by citric acid were studied.     

Cefalosporin complexes with the methylene blue dye and their use in the surgery of infectious endocarditis

Complexation of antibiotics cefazolin and cefoperazone with the methylene blue thiazine dye was studied. Composition (1: 1), stability constants (150±30 M ⁻¹), and solubility of the complexes were determined.     

<Superscript>53</Superscript>Cr NMR study of CuCrO<Subscript>2</Subscript> multiferroic

The magnetically ordered phase of the CuCrO₂ single crystal has been studied by the nuclear magnetic resonance (NMR) method on ⁵³Cr nuclei in the absence of an external magnetic field. The ⁵³Cr NMR spectrum is observed in the frequency range ν_res = 61–66 MHz. The shape of the spectrum depends on the delay tdel between pulses in the pulse sequence τ_π/2–t _del–τ_π–t _del–echo. The spin–spin and spin–lattice relaxation times have been measured. Components of the electric field gradient, hyperfine fields, and the magnetic moment on chromium atoms have been estimated.