Formation of stable water-in-oil emulsions in light and heavy crude oils was shown to involve the buildup of interfacial layer characterized by increased contents of the main emulsifiers, asphaltenes ...and resins. An increase in the proportion of asphaltenes in the interfacial layer, nearly 4-fold for the light oil and 1.3-fold for the heavy oil samples, was accompanied by changes in their elemental and structural-group compositions. The proportions of resins in the interfacial layers exceeded by 25–86% those in the original oils. IR-spectroscopic examination revealed increases in the concentration of carboxy and methylene groups in the asphaltenes and resins from the interfacial layer of the light oil and in the concentration of sulfoxide and carboxy groups from the interfacial layer of the heavy sulfurous oil. The dependence of the surface activity of resins and asphaltenes on pH of the aqueous phase was elucidated. Asphaltenes and resins exhibited decreases in interfacial tension (2.3–3.2-fold maximum) in the pH range 10–12 compared to pH range 4–6, which was due to neutralization of their constituent carboxy groups. Reduction of the interfacial tension in the acidic region was attributed to the presence of sulfoxide groups, possessing the properties of weak bases, in the emulsifiers.
The concentrations of paraffins, asphaltenes, resins, and heteroatomic moieties in crude oils, as well as their ratios, affect the pour point and the formation of asphalt–resin–paraffin deposits ...(ARPD). The paper describes an investigation of these effects for the case of crude oils from the West Siberian oil and gas province. The functional dependence of the amount of ARPD and pour point on the paraffin content and paraffin to asphaltene ratio in crude oils was identified. It was further demonstrated that resins and asphaltenes as well as paraffins may be contained in the deposits formed in crude oils.
Abstract
A standard procedure for characterizing the high-purity germanium detector (HPGe), manufactured by Canberra Industries Inc 1, is performed directly by the company using patented methods. ...However, the procedure is usually expensive and must be repeated because the characteristics of the HPGe crystal change over time. In this work, the principles of a technique are developed for use in obtaining and optimizing the detector characteristics based on a cost-effective procedure in a standard research laboratory. The technique requires that the detector geometric parameters are determined with maximum accuracy by the Monte Carlo method 2 in parallel with the optimization based on evolutionary algorithms. The development of this approach facilitates modeling of the HPGe detector as a standardized procedure. The results will be also beneficial in the development of gamma spectrometers and/or their calibrations before routine measurements.
The aim of the paper is to determine the relationship of the classical model for describing a rarefied gas using the distribution function and its discrete representation. Here we study the role of ...discreteness in the description of a medium in the kinetic theory and the interrelation between interaction of the discreteness and the "continuity" of a media. The question of the relationship between the discreteness of a medium and its description with the help of continuum mechanics is important both when processing experimental data and when going from a continuum model to discrete one in mechanics and physics. There are many studies devoted to the influence of the transition from a continuous to discrete medium in computational mathematics, but there is no study of inverse processes. The work related to the formulation of conservation laws as conditions of the equilibrium of forces and moments of forces, as well as the action of additional flows on the sides of an elementary volume, was carried out earlier. After refinement, non -symmetric stress tensor was obtained. The method for calculating this tensor was proposed. The equations for a gas were found from the modified Boltzmann equation and from the phenomenological theory. Inaccuracy leading to the symmetry of the stress tensor arises when calculating the Lagrange function of particles as the sum of pairwise interacting particles and the unchanged position of the inertia system center.
The effect of an inhibitory composition based on an amphiphilic polymer of polyacrylate and stearic acid on the composition of paraffinic hydrocarbons in asphalt–resin–paraffin deposits (ARPDs) of ...high-paraffin oil was studied. It was shown that the molecular weight distributions of paraffinic hydrocarbons in the ARPDs were different upon the addition of the amphiphilic polymer and the composition to oil. The action of the polymer led to a decrease in the total concentration of C
16
–C
21
hydrocarbons and an increase in the fraction of high-molecular-weight C
22
–C
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hydrocarbons. On the contrary, the use of stearic acid as a surfactant in the composition decreased the amount of high-molecular-weight paraffin hydrocarbons.
For the past ten years, the IVG.1M research reactor has been converted from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Currently, the final stages of the IVG.M reactor ...conversion, including physical and energy start-ups, are underway. As part of the physical start-up, one of the objectives was to conduct physical studies on the power distribution across the radius and height of the fuel assemblies in water-cooled technological channels. Studies were carried out using the activation gamma-spectrometric method based on correspondence between energy release and measured gamma-radiation activity of fission or activation products. The ENREDI program was used to determine the detailed relative power distribution over radial cross section of fuel assembly. During these experimental studies, relative power distribution along the height and radial cross section of the IVG.1M fuel assembly, as well as power peaking factors were obtained. These studies will make it possible to evaluate the changes in the IVG.1M reactor fuel power profile after the fuel enrichment reduction, and to verify the accuracy of neutronic simulations.
•The power distribution in the IVG.1M reactor fuel was investigated experimentally.•Comparison of power distribution for LEU and HEU fuels was carried out.•After the reactor conversion, the internal block effect of the fuel increased.•The results can be used for checking the reliability of neutron-physical simulations.
During the physical start-up of the IVG.1M research reactor, which involved the conversion to low-enriched uranium fuel, various studies were conducted using physical mock-ups of the fuel assemblies. ...The mock-up consisted of 468 model low-enriched uranium fuel elements that were cut into three sections without end coatings at the cut locations. This configuration allowed for the simulation of fuel element decompression and the experimental determination of fission product release into the coolant.
The coolant samples obtained from the mock-up were analyzed using a gamma-spectrometer equipped with a high-purity germanium detector. As a result of the studies, the activities of fission products in the coolant and the averaged relative fission product release were determined. The relative release is defined as the ratio of the release rate of reference fission products to its birth rate.
For the first time, fission product release was experimentally obtained in a situation simulating the decompression of IVG.1M fuel cladding.
•The radiation characteristics of the coolant at the physical start-up determined.•The relative release of fission products from leaky fuel elements are determined.•Sr, I, Te, Rb mainly contribute to the fission products release in leaky fuel elements.•The results will be used to control the increase in fission product release in coolant.
The characteristic feature of molecular medicine as medicine based on molecular structure of human genome data, is its individual character. It is focused on correcting pathological process in ...specific individual considering unique characteristics of its genome. The other most important feature is its expressed preventive direction. The complete genome information can be obtained well before the onset of disease. The appropriate preventive measures can completely eliminate or significantly prevent development of severe disease. The establishment of gene network of every multi-factorial disease, identification of central genes and genes-modifiers in it, analysis of association of their alleles with disease, development on this basis of set of preventive measures for specific patient constitute conceptual and methodological basis of predictive medicine. As a result of the examination, information can be obtained concerning particular risk of disease development. The physician, considering the results of molecular genetic analysis, elaborates tactics of pathogenetically justified preventive therapy, i.e. corrects congenital metabolic defect.
A standard procedure for characterizing the high-purity germanium detector (HPGe), manufactured by Canberra Industries Inc., is performed directly by the company using patented methods. However, the ...procedure is usually expensive and must be repeated because the characteristics of the HPGe crystal changes over time. In this work, the principles of a technique for use in obtaining and optimizing the detector characteristics based on a cost-effective procedure in a standard research laboratory were developed. The technique required the geometrical parameters of the detector to be determined as precisely as possible by the Monte Carlo method in parallel with the optimization process based on evolutionary algorithms. The development of this approach facilitated the modeling of the HPGe detector as a standardized procedure. The results would be also beneficial in the development of gamma spectrometers and/or their calibrations before routine measurements.
•HPGe characteristics were obtained and optimized using a cost-effective procedure.•Geometry parameters of HPGe were determined using Monte Carlo simulation (MC).•Method of evolutionary algorithms was used for optimization in parallel with MC.•Results of this study can be used in both spectrometer development and calibration.
The formation of oil sediment in highly paraffinic oil in the presence of carboxylic and naphthenic acids was studied. The influence of the concentration and composition of acids on the process of ...sediment inhibition and the concentrations of paraffins, resins, and asphaltenes in sediments was demonstrated. In the composition of sediments obtained from oil with the addition of acidic reagents, the amount of light
n
-alkanes increased and the fraction of higher molecular weight hydrocarbons decreased. The concentrations of aliphatic fragments and carboxyl groups in the resins of sediments obtained with the addition of acidic reagents decreased, and the aromaticity coefficient increased. Asphaltenes in the sediment were characterized by a decrease in the concentrations of aromatic structures and carboxyl groups.
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