Isotope (δ13C and δ18O) compositions of dolomites from the Permian evaporitic sequences of the Eastern Russian Plate: Evidence from the Syukeevo gypsum deposit

Carbon and oxygen isotope compositions has been studied in dolomites of the Syukeevo gypsum deposit located in the Eastern Russian Plate. Values of δ13C in the dolomites vary from 0.3 to 6.6 ‰; δ18O, from 28.0 to 36.6‰. It is shown that the dolomites were formed in the epicontinental evaporitic basin in different paleoecological settings. This led to the formation of diverse lithological types of dolomites with peculiar isotope-geochemical features. © 2014 Pleiades Publishing, Inc

Spatial structure of phosphorus-containing heterocycles - Communication 28. Conformation of phenyl radical in 5-phenyl-5-oxo-1,3,5-dioxaphosphorinanes and thiono analogs

1. On the basis of data on the Kerr effect in solutions, the stereoisomers of 5-phenyl-5-oxo- and 5-phenyl-5-thiono-2,4,6-trimethyl-1,3,5-dioxaphosphorinanes, differing in the position of the exocyclic substituents on the P atom, are characterized by nearly parallel orientation of the plane of the benzene ring and the plane of the bonds {Mathematical expression}. In the conformation that we have found, optimal structural conditions are realized for resonance interaction of the π-orbitals of the phenyl radical and the P=X bond. 2. This sort of interaction in the UV spectra is manifested in a bathochromic shift of the benzene absorption bands (particularly λ2) and their intensification. In the sulfides, the absorption bands of the benzene overlap those of the thiophosphoryl group. © 1982 Plenum Publishing Corporation

Protective Action of Xymedon on the Morphological Structures of the Pancreas of the Rat in Ischemia

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Pathologic processes associated with the effect of ischemia on the pancreas are not yet fully investigated and searching for ways of reduction of the damaging effect of ischemia for providing full organ regeneration are of certain interest. Protective properties of xymedone with regard to pathologic processes in pancreas were studied on a model of total ischemia created by ligation of the coeliac and cranial mesenteric artery for 0 to 90 min. Pathologic structural changes in the pancreas in case of ischemia lasting up to 30 min are minor and therefore fully reversible. On the contrary, ischemia duration of more than 60 min in the group of animals not injected with xymedone can be seen as critical. We conclude that prior intraperitoneal injection of xymedone in the dose of 3.3 mg/kg helps to delay the development of pathologic processes in pancreatic parenchyma by approximately 30 min

Vibrational spectra and conformational isomerism of 2-phenoxy-5,6-benz-1,3,2-dioxaphosphepins

Using vibrational spectroscopy methods in different aggregate states and solutions with variation of the polarity of the medium, we have studied 2-phenoxy-5,6-benz-1,3,2-dioxaphosphepin and its oxo, thio, and seleno analogs. In the liquid and solutions, they exist as a conformational equilibrium of three forms: two chair forms, differing in the orientation of the phenoxyl radical, and a twist form. The population of the twist form is no more than 25%. The content of the chair conformers is determined by the solvent. In the crystal, all the compounds have the chair form with axial phenoxyl group. © 1989 Plenum Publishing Corporation

Traditional and precision methods for studying porous space of oil-bearing formation

At present, the coefficient of porosity is traditionally determined by the method of Preobrazhensky and by the results of a petrophysical interpretation of well log data. However, there are many examples of the significant error in its determination, which ultimately affects the determination of their filter-capacitance properties, the recovery rate of oil and extracted reserves. In this paper, the porosity coefficients are compared by traditional and precision methods for oil-containing terrigenous reservoirs of the Paschian (Upper Devonian), and Tula and Bobrikovskian (Lower Carboniferous) horizons, as well as carbonate reservoirs of the Tournaisian stage, using the example of one of the deposits in the central part of the Volga-Ural oil and gas province. It is shown that precision methods make it possible to study in more detail the internal pore space of oil-containing reservoirs. X-ray computer microtomography showed the uneven and multidimensional porosity of Devonian sandstones, due to their micro-lamination. The most accurate values of the porosity coefficient from the results of microtomography were obtained for cubes of the smallest size (with linear dimensions of the sample less than 5 mm), so they correspond to a higher resolution of the survey, which allows detecting smaller pores. In this connection, the inverse dependence of the porosity coefficient on the size of the samples was established. Variability of porosity along the layers in the lateral direction is revealed (the property of 'microfaciality'). The combination of traditional and precision methods for determining porosity coefficients will allow us to calculate the oil recovery factor on explored and developed oil deposits more correctly, because additional information on pore size and cavity, connectivity and type of channels, as well as microfacies are taken into account

Geometric structures of phosphorus-containing heterocycles - 22. Pyrocatechol derivatives of phosphorous acid

1. Dipole moments, Kerr constants, and bond polarity and polarizability parameters for phosphorus have been determined for various pyrocatechol derivatives of phosphorous acid. 2. The pyrocatecholaryl phosphites have envelop conformation with gauche-axial oriented OCH3 group. 3. Data on the Kerr effect has been used to calculate the angle of rotation of the plane of the benzene ring relative to the plane of the P-O-C bond in the pyrocatecholaryl phosphites. © 1980 Plenum Publishing Corporation

Spatial structures of phosphorus-containing heterocyclic compounds - XXIV. Conformations of 2-X-4,5,6,7-dibenzo-1,3,2-dioxaphosphepanes

1. 2-X-4,5,6,7-Dibenzo-1,3,2-dioxaphosphenanes (X=Cl, OEt, OPh) have a twist form, and angle of twist with respect to the biphenyl bridge is equal to 41-48°. 2. The ethoxy radical in these compounds is characterized by a gauche orientation with respect to the P-O bond, and the phenoxyl group has a cis conformation. © 1981 Plenum Publishing Corporation

On solving of some nonlinear problems of plasma physics

© 2015 V. S. Zheltukhin et al. The non-linear problem of finding the parameters of interaction of radio-frequency capacitive discharge with the sample placed on the electrode is considered in a local approach. The problem is described by a system of nonlinear initial value problems. Approximate method of solving the problem is proposed. The numerical results for the model problem are given together with their analysis

Vibrational, NMR, photoelectron spectra and conformational analysis of seven-membered heterocycles

The article covered are the general principles of conformational analysis of 7-membered 1,3-dihetero-2-phosphepines and -silepines with one planar unit by means of spectral methods. The quantitative description of all possible conformers is given. Spectral criteria (the most informative bands in vibrational spectra, the shift difference and vicinal couplings in NMR spectra) for structural investigations are derived and on their basis the conformational condition is established depending on the nature of planar units and heteroatoms. © 1990

Steric structure of phosphorus-containing heterocycles Communication 36. 2-dialkylamino-1,3,2-dioxaphosphepines with tetracoordinated phosphorus

In conformity with the data of1H NMR, DM, and the Kerr effect for 2-dialkylamino-2-oxo(thiono, seleno)-1,3,2-dioxaphosphepines, a conformational equilibrium of two forms of twist and chair with an equatorial dialkylamino group is observed in solutions. The equilibrium is displaced in favor of the latter. © 1985 Plenum Publishing Corporation