Impurities In Form Research Articles

Properties of Spin-polarized Impurities — Ferrons, in the Unitary Fermi Gas

A new excitation mode has been predicted to exist in the unitary Fermi gas. It has a form of a spin-polarized impurity, which was dubbed as ferron. It is characterized by a closed nodal surface of the pairing field surrounding a partially spin-polarized superfluid region, where the phase differs by $\pi$. In this paper, we discuss the effect of temperature on the generation of the ferron and the adiabaticity of the spin-polarizing potential together with ferron's ground state properties.

Бесщелочная окислительная демеркаптанизация углеводородов

В процессах нефтедобычи и переработки всегда остро стоял вопрос удаления или перевода в нетоксичные формы легколетучих сернистых примесей (H2S, CH3SH, C2H5SH). В настоящее время в связи с исчерпанием запасов малосернистой нефти и значительным ростом потребления ее сернистых и высокосернистых видов эта проблема приобретает все большую актуальность. Возможными вариантами ее решения являются усовершенствование и модернизация существующих подходов и технологий, разработка и реализация новых. Например, интерес может представлять технология неэкстракционной (бесщелочной) демеркаптанизации, в основе которой лежит прямое каталитическое окисление H2S и RSH до нетоксичных и устойчивых ди- и полисульфидных форм непосредственно в углеводородной среде, исключая стадию их экстракции щелочными растворами, а также утилизации образующихся в больших объемах сернисто-щелочных стоков. Приведены результаты лабораторных испытаний по оценке активности гомогенных катализаторов на основе комплексов меди в реакции окисления H2S и RSH кислородом воздуха в нефти и темных нефтяных фракциях, а также основные результаты опытно-промышленных испытаний, проведенных по демеркаптанизации газоконденсатного мазута Астраханского газоперерабатывающего завода и нефти месторождения Алибекмола. По сравнению с известными способами предлагаемая технология отличается отсутствием токсичных сернисто-щелочных стоков, что обеспечивает безопасность, как на стадии очистки, так и при транспортировке и хранении нефти и нефтепродуктов. A problem of removal of volatile sulfur impurities (H2S, CH3SH, C2H5SH, etc.) from hydrocarbon raw materials or their conversion into non-toxic forms has always been challenging for industrial processes of oil production and refining. Currently, due to the depletion of low-sulfur oil resources and a significant increase in the oil consumption with (high) sulfur content, this problem has gained an increasing importance. Possible solutions include approaches for improving and modernizing existing technologies along with the development and implementation of novel procedures. A representative example of the relevant technology is non-extraction (alkaline) demercaptanization, which is based on the direct catalytic oxidation of H2S and RSH into non-toxic and stable di- and polysulfide forms directly in a hydrocarbon medium, thereby excluding the stage of their extraction with alkaline solutions, as well as the stage of disposal of large volumes of sulfur-alkaline waste. The paper presents results of laboratory studies aimed at evaluating activities of homogeneous catalysts based on copper complexes which have been applied for oxidation of H2S and RSH by atmospheric oxygen in oil and dark oil fractions media, as well as general results of pilot scale testing conducted on demercaptanization of gas condensate fuel oil derived from the Astrakhan gas processing plant and oil samples from Alibekmola field. Compared with conventional procedures, the proposed technology is characterized by the absence of toxic sulfur-alkaline effluents, which ensures safety, both at the stage of oil refining and during transportation and storage of oil and oil products.

Computation of Relative Variances of Magnetization and Susceptibility in a Disordered Ising Model: The Results of Computer Simulation

Based on the Monte Carlo method, the relative variances of magnetization Rm and susceptibility Rχ in the disordered spin lattice Ising model are computed as a function of the degree of the dilution of a disorder. It is shown that the introduction of a disorder in the form of nonmagnetic impurities in the three-dimensional Ising model produces nonzero values for Rm and Rχ at the critical point.

A ferroparticle in a magnetizable disperse medium made up of particles of a like nature: Specific aspects of susceptibility determination

Abstract It is noted that one of the fundamental questions in the magnetophoresis problem, namely, the determination of the magnetic susceptibility of ferroparticles χ remains poorly understood. This question is of the most importance for “different-kind” ferroparticles contained in processing media in the form of impurities. It is pointed that the approaches to the determination of χ have not been adequately studied and that there is an opportunity of implementing the approach based on the data on the magnetic susceptibility of a disperse specimen χ with a disperse phase of particles to be studied provided that the following rules are observed. First, in addition to obtaining data on the specimen χ (experimental data; for a necessarily small-volume specimen the ponderomotive method is advisable), the volume fraction of the ferroparticles in the specimen γ shall be known. Second, “rigid” specimens, in particular, in the form of powder shall be used. The use of colloidal or suspension specimens shall be avoided because of the unobstructed movement of ferroparticles leading to the formation of their chains and aggregates, which disturbs the condition of the specimen. Third, in order to provide sufficiently long distances between the ferroparticles and to eliminate their mutual magnetic effect, their concentration in the specimen shall be low (γ ≤ 0.15–0.2). At these values of γ the concentration dependences of χ are fairly linear; therefore, values of χ can be determined as χ = χ /γ. Fourth, it shall be taken into account that in the post-extreme (for the susceptibility) range of the magnetic-field strength H = 120–700 kA/m the dependence of the susceptibility χ on the magnetic-field strength has the exponential form: χ ∼ H - 0.75 . This makes obtaining an extended experimental-calculation strength dependence of χ easier provided that a single control value of χ is known. Fifth, the same is also true for the “affined” dependence of the susceptibility of the particles themselves χ on the magnetic-field strength, namely, χ ∼ H−0.75. The approach described in this work has been sufficiently substantiated using concentration and field dependencies of χ for various powder specimens (with magnetite particles, ferroimpurities of sugar and wheat farina, condensate, ammonia, ammonia aqua, circulating water, steam, etc.).

Perspective directions of metallurgy and steel metal science development

The task of principal (multiple) increase of complex of service parameters (often being hard compatible) and steel quality under conditions of costs decrease becomes more and more actual. The solution is possible by creation and application of new principles and approaches based, first of all, on adequate physical and chemical predicting methods and effective technological skill of control non-metallic inclusions, forms of impurities, phase isolations, structure state, including homogeneity of the metal volume. A complex approach to prediction, analysis of phase composition, structure state and steel properties elaborated to implement this progressive direction. It has an important feature like elaborated in details scientific principles. The principles allow not only to make effective the development of new steel and technologies of their production at minimum costs, but also to reveal the content, directions and intensity of processes having place during metal processing. It was illustrated at the example of microalloyed (stabilized) by titanium super-high-carbon IF steel. Importance of accounting of regularity of phase isolations forming kinetics shown, that can result in considerable change of their characteristics and steel properties. This circumstance can be used for unification of chemical composition or development of cassette technologies production, for example, from IF-steels of the same chemical composition, of rolled products of different assortment or strength class. It was shown, that the complex phase isolations forming takes place with participation impurities and elements presented in the steel. Therefore there arose wide possibilities of considerable increase of complex of properties at decreasing of costs. Presence of deformation considerably accelerates the processes of nano-size phase isolations forming not only during rolling, but also during parts manufacturing by hot stamping, combined with steel quenching. This allows to increase their strength by 300–400 MPa additionally to martensitic structure. It is possible, apart from principal perfection of parameters of service characteristics stability, to reach considerable increase of composition homogeneity, structure and properties in the whole metal volume by non-metallic inclusions forming control. Forming of silicate glassy inclusions in low-alloyed steels improves principally the macro- and microstructure of CC billet and impact toughness of rolled products KCV–40 (420–445 J/сm2 ). Their presence in the steel stipulated by kinetic reasons. Additional substantial increase of composition homogeneity, structure and microalloyed steels properties can be reached during the rolling process by return redistribution of components from the axis zone to the surface of the rolled product. High efficiency of the above-mentioned approaches at present has been confirmed by development an array of pipe, structural, automobile steels and highly efficient technologies of their production.

Forms of occurrence of selected alloying elements in slag from an electric arc furnace

The chemical composition of steel slag is dependent on the type of the charge and thus the alloying elements used in the process. The conducted tests of slag from an electric arc furnace have indicated that their chemical composition contains elements classified as so-called alloying elements – with the highest content of manganese and chromium. Besides these, smaller amounts of cobalt Co, molybdenum Mo, titanium Ti and tungsten W were identified. Due to the significant concentration of Mn and Cr, it was assumed that these elements were added to the alloy on purpose to achieve certain steel properties. The presence of Co, Mo, Ti and W may be related to the type of scrap introduced into the process. To determine what components of the slags are the analysed metals related with, phase composition tests of slag were conducted based on electron scanning microscopy and X-ray diffraction method. It was established that chromium occurs in the form of impurity in the solid solution of FeO-MnO-MgO, called the “RO phase” and forming characteristic dendritic forms. Wolfram, on the other hand, creates its own cryptocrystalline phases classified as tungstates: hübnerite and ferberite. The remaining metals, that is Co, Mo, and Ti occur in a dispersed state in the amorphous substance.

Calculation of a two-phase system of a liquified hydrocarbon gas

Liquefied hydrocarbon gases are a mixture of chemical compounds, consisting mainly of hydrogen and carbon with different molecular structures. The main components of liquefied hydrocarbon gases are propane and butane, containing lighter hydrocarbons (methane and ethane) and heavier ones (pentane) in the form of impurities. All of these components are saturated hydrocarbons. The composition of liquefied hydrocarbon gases can also include unsaturated hydrocarbons: ethylene, propylene, butylene. Butane-butylenes may be present as isomeric compounds (isobutane and isobutylene). When designing and operating liquefied petroleum gas systems, it is necessary to take into account the external equilibrium between the liquid and the gas. The paper analyzes the change in the ratio of components, in which the relative content of lighter hydrocarbons will decrease, while the content of heavier ones will increase. With an intensive flow of gas, the temperature of the liquid will drop sharply, estimation will be disturbed, and the vessel will freeze. Therefore, when operating balloon installations, it is very important to consider safety issues that are associated with containers’ filling, as well as with the change in the composition of hydrocarbon gases mixture. The discussed issues related to the calculation of a two-phase system of liquefied hydrocarbon gas can improve the operating conditions of the systems.

Exponents of Spectral Functions in the One-Dimensional Bose Gas

The one-dimensional gas of bosons interacting via a repulsive contact potential was solved long ago via Bethe’s ansatz by Lieb and Liniger (Exact Analysis of an Interacting Bose Gas. I. The General Solution and the Ground State). The low energy excitation spectrum is a Luttinger liquid parametrized by a conformal field theory with conformal charge c = 1 . For higher energy excitations the spectral function displays deviations from the Luttinger behavior arising from the curvature terms in the dispersion. Adding a corrective term of the form of a mobile impurity coupled to the Luttinger liquid modes corrects this problem. The “impurity” term is an irrelevant operator, which if treated non-perturbatively, yields the threshold singularities in the one-particle and one-hole Green’s function correctly. We show that the exponents obtained via the finite size corrections to the ground state energy are identical to those obtained through the shift function.

About chemical form and binding energy of 14C in irradiated graphite of uranium-graphite nuclear reactors

Issues associated with handling irradiated graphite of uranium-graphite nuclear reactors are examined. It is demonstrated that selection of approaches, methods and means for handling irradiated graphite are determined by the form of occurrence and binding energy of long-lived 14C radionuclide with graphite crystalline lattice. The purpose of the present study is the determination of possible chemical compounds in which 14C can be found and assessment of fastness of its binding in the structure of irradiated graphite. Indigent and foreign experience of handling graphite radioactive wastes was analyzed, calculations and measurements were performed. Information was provided on the channels of accumulation of 14C in the structure of reactor graphite and it was demonstrated that the largest quantities of the radionuclide in question are generated according to the reaction 14N(n, p)14C. Here, most part of radioactive carbon is generated on 14N nuclei found in the form of impurities in non-irradiated graphite and in the composition of gas used for purging nuclear reactor in the process of operation. 14C radionuclide generated according to 14N(n, p)14C nuclear reaction is localized in the near subsurface graphite layer (in the near subsurface layer of pores) at the depth of not more than 50 nm. Analysis was performed of possible chemical compounds which may incorporate radioactive carbon. It was established that the form of occurrence is determined by the operational properties of specific graphite element in the reactor core. 14C binding energy in the structure of irradiated graphite was evaluated and depth of its penetration in the structure was calculated. It was established that selective extraction of this radionuclide is possible only under elevated temperatures in weakly oxidizing environment which is explained by the binding energy reaching up to 800 kJ/mole in the process of chemical sorption of 14C on the surface of graphite and depth of its occurrence equal to ~ 70 nm in the course of ion implantation. It was demonstrated that radioactive carbon generated according to 13C(n, γ)14C nuclear reaction is uniformly distributed among graphite elements and possesses binding energy ~477 kJ/mole. Its selective extraction is possible only under the condition of destruction of graphite crystalline lattice and organization of the process of isotopic separation. The obtained results allow recommending the most efficient methods of handling irradiated graphite during decommissioning uranium-graphite reactors.

Identification, Synthesis, and Control of Process-Related Impurities in the Antipsychotic Drug Substance Brexpiprazole

This article describes the identification, synthesis, and control of several unknown related substances present in the form of critical impurities that were observed during the process development for the antipsychotic drug substance brexpiprazole (BRX). On the basis of liquid chromatography–mass spectrometry (LC–MS) evidence of impurities and analysis of the employed synthetic route of BRX, the structures of the unknown impurities were proposed. Many critical impurities were synthesized, and their chemical structures were established using different spectroscopy techniques. To the best of our knowledge, this is the first report where several new impurities were recognized, addressed, and controlled effectively during the development of a robust and efficient process for the BRX drug substance.

Leaching characteristics and kinetics of the metal impurities present in rice husk during pretreatment for the production of nanosilica particles

Fundamental studies on the removal of metal impurities are essential for the production of nanosilica by combustion. This study reports the leaching characteristics, leaching kinetics and occurrence form of the metal impurities present in rice husk based on acid pretreatment. Acid pretreatment removes most of the metal impurities present in rice husk. In particular, 98 wt% removal of potassium can be reached. The acid concentration, leaching time and reagent type have significant effects on the leaching of metal impurities, and optimal conditions exist for the acid pretreatment process. Furthermore, the leaching of metal impurities occurs through two stages, and parts of the metal impurities exist in organic-bound form, which can be leached through ion exchange. The results show that the pseudo-second-order model is suitable for describing the leaching kinetics of the metal impurities present in rice husk, and empirical formulas for predicting the metal contents leached from rice husk during acid pretreatment at ambient temperature are also obtained. Additionally, the different occurrence form and quantities of metal impurities in rice husk lead to different leaching effects, which strongly influences the chemical properties and quality of the obtained silica particles.

Weak Universality in the Disordered Two-Dimensional Antiferromagnetic Potts Model on a Triangular Lattice

The critical behavior of the disordered two-dimensional antiferromagnetic Potts model with the number of spin states q= 3 on a triangular lattice with disorder in the form of nonmagnetic impurities is studied by the Monte Carlo method. The critical exponents for the susceptibility γ, magnetization β, specific heat α, and correlation radius ν are calculated in the framework of the finite-size scaling theory at spin concentrations p = 0.90, 0.80, 0.70, and 0.65. It is found that the critical exponents increase with the degree of disorder, whereas the ratios and do not change, thus holding the scaling equality $$\frac{{2\beta }}{\nu } + \frac{\gamma }{\nu } = d$$ . Such behavior of the critical exponents is related to the weak universality of the critical behavior characteristic of disordered systems. All results are obtained using independent Monte Carlo algorithms, such as the Metropolis and Wolff algorithms.

Physicochemical aspects of the preparation of high-purity arsenic-containing substances from various raw materials

We have developed physicochemical principles of the preparation of high-purity arsenic-containing substances from conventional (As2S3, As4S4, and FeAsS sulfide ores) and unconventional raw materials (chemical warfare (lewisite) detoxification products, semiconductor fabrication waste, and nonferrous metals industry waste). We have identified and investigated transformations of chemical forms of impurities in the recovery, synthesis, and ultrapurification of arsenic-containing compounds. The observed fundamental aspects of the behavior of impurities, with allowance for the origin of the raw materials to be processed, were taken as a basis for designing combined, environmentally friendly processing schemes for the preparation of high-purity arsenic and arsenic compounds (AsCl3 and AsH3).

First occurrence of Pd-bearing galena (Sedova Zaimka copper–nickel mineralization, Western Siberia)

The paper presents data on the chemical composition and mineral association of Pd-bearing galena, discovered in hydrothermal–metasomatic sulfide Cu–Ni ores of the Sedova Zaimka mineralization (Western Siberia). In the Sedova Zaimka mineralization, galena is an accessory mineral and occurs in association with pyrrhotite, pentlandite, chalcopyrite, sphalerite, argentopentlandite, tsumoite, and native bismuth. The Pd contents in galena are 0.5–0.9 wt %. Palladium occurs in galena in the form of isomorphic impurities and is not related to microinclusions of Pd-bearing minerals.

Chemistry and technology of special-purity trimethyl alkoxysilanes

Technology of high-purity trimethylalkoxysilanes was developed. To rule out the lability of chemical forms of trace impurities, an additional stage of the ion-exchange purification of the starting alcohols is introduced into the classical scheme of synthesis of trimethyl alkoxysilanes and deep rectification purification. To raise the yield of the final product, the stage of azeotropic distillation with azeotrope-forming components is introduced. Construction materials are chosen and a gas-chromatographic analysis of the impurity composition of trimethylalkoxysilanes was made. The development was performed with the use of CALS technologies.

Mechanism on M (M[dbnd]Ni, Mo, Ni[sbnd]Mo) as deep level impurity reducing the TCR of Si-rich Cr[sbnd]Si resistive films

CrSi–M (MNi, Mo, NiMo) resistive films were prepared by magnetron sputtering technique at the same process conditions. Experimental results shows that the metal M can reduce the temperature coefficient of resistance (TCR) of Si-rich CrSi resistive films, and that the resistive films follow the sequence of CrSiMo (6.34 at%) < CrSiNi (9.97 at%) < CrSiNi (6.08 at%)Mo (2.47 at%) according to TCR tending to zero. XRD analysis reveals that CrSi2 is the main conductive phase in the prepared CrSi–M resistive films. In order to explore the reasons that M can reduce the TCR of Si-rich CrSi resistive films, first principles was used to study the influence of M on the performance of CrSi2 from state density and band structure. The first-principles study on M-doped CrSi2 shows that M may exist in CrSi2 semiconductor in the form of deep level impurity, and an energy band model on both Ni and Mo-doped CrSi2 is constructed to reflect the results of first-principles simulation. Based on the established model, a mechanism is proposed that deep level impurities as electron traps capturing electrons and the formation of tight-binding excitons can suppress the non-equilibrium hot carriers against being contributed to the conductivity of CrSi2 semiconductor. As a result, the TCR of Si-rich CrSi resistive films is reduced due to the doping of M as deep level impurity.

Kinetics analysis of leaching phosphorus from rice husk ash assisted by ultrasound

ABSTRACTThe distribution state and occurrence form of impurities of rice husk ash were analyzed and identified by SEM/EDS and XRD. The reaction kinetics for the leaching phosphorus have been studied to determine the effect of process parameters, such as stirring speeds, temperatures, HCl concentrations, particle sizes, ultrasound powers and frequencies. The kinetic data fit a new transformation of shrinking core model. The apparent activation energy is 81.21 kJ/mol. And the reaction orders with reference to HCl concentrations, particle sizes, ultrasound powers and frequencies are determined to be 2.54, −0.59, 1.55 and −0.92, respectively. The semi-empirical equation is as follows:

Combining selective sequential extractions, X-Ray Absorption Spectroscopy, and X-Ray Powder Diffraction for Cu (II) speciation in soil and mineral phases

Interaction of Cu (II) ions with the matrix of soil and mineral phases of layered silicates was assessed by the Miller method of selective sequential fractionation and a set of synchrotron X-ray methods, including X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XANES). It was shown that the input of Cu into Calcic Chernozem in the form of monoxide (CuO) and salt (Cu(NO3)2) affected the transformation of Cu compounds and their affinity for metal-bearing phases. It was found that the contamination of soil with a soluble Cu(II) salt increased the bioavailability of the metal and the role of organic matter and Fe oxides in the fixation and retention of Cu. During the incubation of soil with Cu monoxide, the content of the metal in the residual fractions increased, which was related to the possible entry of Cu in the form of isomorphic impurities into silicates, as well as to the incomplete dissolution of exogenic compounds at the high level of their input into the soil. A mechanism for the structural transformation of minerals was revealed, which showed that ion exchange processes result in the sorption of Cu (II) ions from the saturated solution by active sites on the internal surface of the lattice of dioctahedral aluminosilicates. Surface hydroxyls at the octahedral aluminum atom play the main role. X-ray diagnostics revealed that excess Cu(II) ions are removed from the system due to the formation and precipitation of coarsely crystalline Cu(NO3)(OH)3.

Computer simulation of diluted magnetic nanostructures

A Monte-Carlo method is used to simulate nanostructures of magnetic materials containing weakly frozen disorder in the form of nonmagnetic impurities. Systems with linear sizes L = 20–60 and spin concentrations p = 1.0 and 0.90 are considered. Temperature dependences of the thermodynamic parameters, specific heat C, susceptibility χ, and the fourth order Binder cumulants for particles with free boundaries are constructed. It is shown that a second order phase transition is observed in this model of small magnetic particles with impurities.

Initiation and the Ritual Purification from Sin: Between Qumran and the Apostolic Tradition

Second Temple Judaism witnessed the rise of a new approach to sin impurity. While in the Hebrew Bible sin impurity was associated with improper actions, and there was no formula to dissipate it, this form of impurity underwent a process of reification during the Second Temple period and was consequently identified with specific objects and people, such as idols, gentiles and “outsiders” in general. Consequently, the distinction between moral and ritual impurity was blurred, and practices for the disposal of bodily impurity were gradually applied to carriers of sin impurity. Arguably, both Qumran sectarians and Christians shared this Second Temple tendency, and it shaped their common ritual language. In this article, I examine the gradual development of initiation as a locus of purification from sin impurity in various Qumran texts and in the Christian Apostolic Tradition. The two corpora share the challenge of expelling the impure presence of sin through concrete ritual patterns of bodily purification. Although they seem to differ in their choice of ritual resources, in both cases the principles of gradual bodily purification merge with the language of exorcism to create a separate purification procedure in addition to the initial rite of initiation.