Adsorption of mono- and multivalent cat- and anions on DNA molecules

Adsorption of monovalent and multivalent cat- and anions on a deoxyribose nucleic acid (DNA) molecule from a salt solution is investigated by computer simulation. The ions are modelled as charged hard spheres, the DNA molecule as a point charge pattern following the double-helical phosphate strands. The geometrical shape of the DNA molecules is modelled on different levels ranging from a simple cylindrical shape to structured models which include the major and minor grooves between the phosphate strands. The densities of the ions adsorbed on the phosphate strands, in the major and in the minor grooves are calculated. First, we find that the adsorption pattern on the DNA surface depends strongly on its geometrical shape: counterions adsorb preferentially along the phosphate strands for a cylindrical model shape, but in the minor groove for a geometrically structured model. Second, we find that an addition of monovalent salt ions results in an increase of the charge density in the minor groove while the total charge density of ions adsorbed in the major groove stays unchanged. The adsorbed ion densities are highly structured along the minor groove while they are almost smeared along the major groove. Furthermore, for a fixed amount of added salt, the major groove cationic charge is independent on the counterion valency. For increasing salt concentration the major groove is neutralized while the total charge adsorbed in the minor groove is constant. DNA overcharging is detected for multivalent salt. Simulations for a larger ion radii, which mimic the effect of the ion hydration, indicate an increased adsorbtion of cations in the major groove.Comment: 34 pages with 14 figure

Measurement of the forward energy flow in pp collisions at &#8730;<span style="text-decoration:overline">s</span>=7 TeV

The energy flow created in pp collisions at s√=7 TeV is studied within the pseudorapidity range 1.9&#60;η&#60;4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by Pythia-based and cosmic-ray event generators, which provide different models of soft hadronic interactions

Secondary dolomitization of the Domanik black shales as an indicator of gas-water hydrocarbon-containing fluids upward migration in the Tatarstan territory

© 2020 IOP Publishing Ltd. All rights reserved. The share of unconventional oil reserves is high in Russia and Volga-Ural region, including shale oil reservoirs. It contains around 65% of the total volume of hydrocarbon reserves in region, according to various data. Shale hydrocarbons are widely used in Russia. The main part of the Domaniki oil black shale is confined to carbonate-siliceous carbonaceous complexes of the Domanik horizon of the Francian stage of the Upper Devonian system. According to previous studies in the Domanik formation sedimentary complexes of the Volga-Ural oil and gas province, two types of rocks are distinguished - the Domanikites themselves and Domanikoids. Domanikites contain from 5 to 20% organic matter. Both types of carbonaceous rocks have a practically similar lithological composition. The difference between them lies in variations in siliceous component content and number of authigenic minerals. If content of very fine-grained silica was determined by primary sedimentation factors, then authigenic minerals are indicators of secondary lithogenesis processes. In this work, an attempt is made to compare organic matter content with dolomite mineralization, which is an active agent in mineral formation

Facies variability of pennsylvanian oil-saturated carbonate rocks (Constraints from bashkirian reservoirs of the South-East Tatarstan)

© 2020, Georesursy LLC. All rights reserved. One of the strategic ways of the old oil-producing regions is to further prospecting for potentially promising areas for hydrocarbon. One of these exploration areas is the Volga-Ural region. These reservoirs consist of Carboniferous carbonate rocks, which contain high viscous hydrocarbons and are characterized by complex facies architecture and reservoir properties influenced by diagenesis. The high degree of facies variability in the studied area does not allow reliable distribution of potential reservoir rocks not only between different areas but even within the same oil field. Based on textural and compositional features of carbonate facies, 5 main facies associations were identified and characterized with respect to the depositional settings in the Bashkirian basin. The facies associations correspond to: distal middle ramp facies, open marine proximal middle ramp facies, high-energy innershoal facies, inner ramp facies of restricted lagoons, facies of affected by subaerial exposures. From west to east in the study the following trends in facies characterare identified: 1) a decrease open marine middle ramp facies and in the total thickness of the Bashkirian sections; 2) an increase in evidences of sub aerial exposures; 3) a decrease in the proportion of potential reservoir rocks. A general shallowing of the depositional setting was identified in an eastward direction, where potentially promising reservoir facies of shallow high-energy environments were replaced by facies of restricted lagoon and facies affected by subaerial exposures and meteoric diagenesis (palaeosols, dissolution). The applied approach based on detailed carbonate facies analysis allows predicting the distribution of potentially promising cross-sections within the region

HIGH-CURRENT DIFFUSE DISCHARGE WITH THE EXPLOSIVE CATHODE PROCESS

Quasi-stable glow discharge phase is known to be characteristic for the pulse breakdown of gases by the uniform initiation of initial electrons. The papers [1-3] show that the contraction of the glow discharge can be schematized as follows. At first the cathode spot is formed on account of the cathode instability and of the explosive emission. Then the current density increases in the discharge column against the cathode spot and one can observe a diffuse channel bound to the spot against a background of the glow discharge. The high-conductive contracted spark channe1 germinates along the diffuse channel on the cathode and the anode sides at the third stage. The investigations carried out in noble gases (Ar, Kr, Xe) and in noble gases with small additions of haloid-contained compounds (SF6, CCl4) showed a great number of the cathode spots and diffuse channels to be ignited in the interelectrode volume [4,5]. These channels form a column of a homogenous plasma when mixing. The discharge involved was called as a high-current diffuse discharge (H-C.D.D.). At present there are represented the results on investigations of H-C.D.D.

Effect of Annealing, Stoichiometry, and Surface on Magnetism of (Pr,Dy)FeCoB Microparticles Ensemble

Magnetic properties of powder (Pr,Dy)FeCoB ferrimagnetic alloys and effects of annealing, surface states were analyzed. X-ray photoelectron spectroscopy and Mössbauer spectra of powders indicate the effect of surface states on phase composition and magnetic properties of the studied powder, if particles average size is smaller than 10 μm. Effect of stoichiometry on magnetic anisotropy was found. Thermal stability of anisotropy field was proved by replacement of Fe atoms with Co atoms

Mineralogical and lithological properties of Domanikites from the south-east of Tatarstan Republic

© 2020 IOP Publishing Ltd. All rights reserved. The article was described main types of rocks - mudstones, carbonate-siliceous rocks, containing organic matter and carbonate breccia, based on detailed analysis of rock samples from Semiluksky horizons of Upper Devonian black shale formations, Volga-Ural region, Russian Federation. Different structures and texture features, mineral composition, and content of organic matter characterized selected types of rocks. Only in the carbonate-siliceous type of rocks is the high content of organic matter, about 9%. It was found direct dependence between the content organic matter and content in rocks silica minerals (quartz and chalcedony). Such dependence caused by joint precipitation silica minerals and accumulation of organic matter in the seafloor in conditions of active seepage of hydrothermal fluids. The presence of an abundance of biophilic elements in ascending fluids led to an explosion of biota and widespread of silica organisms. This hypothesis doesn't disagree with any authors but considers the significant contribution of fluid factor to the deposition of Semiluksky formations