Stationary Concentration Research Articles

Grain-size composition effect on flexural response and pore structure of cementitious tail-rock fills with fiber reinforcement

This paper explores the grain-size composition effect on flexural and micro-structural features of fiber reinforced cementitious tail-rock fill (FRCTRF). The FRCTRF mixes considered contained a stationary solid concentration of 70 wt% and a cement/tail rate of 1:6, and were cured for an age of 7-day for strength tests and microstructure. Three-point bending test shows that FRCTRF’s bending property is upgraded by totaling gravel rock. Adding fiber to FRCTRF’s bottom can enhance its peak deflection. With rising gravel particle size/dosage, FRCTRF’s peak deflection displays a trend of falling first and then growing. Accumulating polypropylene fiber could advance FRCTRF’s post-peak strength features as well. FRCTRF sample containing gravel has a large stress drop, and adding gravel rock could essentially boost FRCTRF’s post-peak brittle-ability. In conclusion, this study provides a strong scientific and theoretical underpinning for optimizing artificial false roofs employed recently in modern underground metalliferous mining operations.

Theory of Turing pattern formation and its experimental realization in the CIMA reaction system in the presence of materials lowering the diffusivity of activators

In 1952, Alan Turing accomplished a pioneering theoretical study to show that the coupling of nonlinear chemical reactions and diffusion leads to the instability of spatially homogeneous states. The activator and inhibitor are synthesized as intermediates of the reaction system in the Turing model. Turing found that spatially periodic stationary concentration patterns are spontaneously generated when the diffusion coefficient of the activator is lower than that of the inhibitor. The first experimental realization of the Turing pattern was achieved in 1990 in a chlorite–iodide–malonic acid (CIMA) reaction system. Iodide and chlorite anions act as the activator and inhibitor of this reaction system, respectively. Although there is no significant difference in the diffusion coefficient of iodide and chlorite anions, the Turing pattern was generated because starch was added to the gel reactor to enhance the color tone. This formed a complex with iodide to inhibit its diffusion to satisfy the condition for the Turing instability. Several examples were found after this finding. We focused on the high affinity of quaternary alkyl ammonium cations to iodide. The CIMA reaction was performed in an open gel reactor by adding a quaternary alkyl ammonium cationic surfactant. In addition, the polymer gel consists of the quaternary alkyl ammonium group as the side chain was utilized for the open gel reactor. The micelles of the surfactants and the polymer gels trapped iodide in their vicinity as a counter anion to lower the effective diffusivity to satisfy the condition for the Turing instability.

Superoxide-producing associates from gastrointestinal bacteria: stimulation of its growth by exogenous superoxide-producing complex from raspberries

Aerobic organisms including the gut microbiota have an essential antioxidant status, as a result of which these bacteria protect organisms from various pathologies and diseases. The goal of the given investigation is (1) the isolation and purification of the isoforms of endogenous О2 −-producing associate from gastrointestinal bacteria (Lactobacillus rhamnosus, Lactobacillus acidophilus, Bifidobacterium bifidum); (2) determination of the effective concentrations of exogenous О2 − produced by a complex of NADPH-containing protein component and Fe(III) (NPC-Fe(III)) from raspberries on the growth of the gastrointestinal bacteria in a nutrient medium in vitro. Ion-exchange chromatography on cellulose DE-52 and gel filtration on Sephadex G-100 at the pH of 9.5 was used to isolate and purify the NLP-Nox isoforms. Specific maximal optical absorption spectra of the Nox isoforms were observed in a weakly opalescent aqueous solution of the NLP-Nox isoforms. The specific contents of these NLP-Nox isoforms, as well as their composition, the stationary concentration of produced О2 −, and the mechanism of О2 − production were determined. The stimulating effect on the growth of these gastrointestinal bacteria in the nutrient medium of MRS broth and MRS agar in vitro under the influence of О2 −, as a product of a new thermostable and acid-stable complex NPC-Fe(III) was determined. The NPC-Fe(III) complex, from raspberries was determined as well. Thus, for the first time, the isolation and purification of О2 −- producing thermostable NADPH-containing lipoprotein–NADPH oxidase (NLP-Nox) associate from gastrointestinal bacteria membranes (continuously producing О2 − under the aerobic conditions), and the stimulation of these bacteria growth by О2 − formed by the complex from raspberries were demonstrated.

Copper-catalysed electrophilic carboamination of terminal alkynes with benzyne looked at through the computational lens.

A detailed computational mechanistic study of the copper-catalysed three-component-type electrophilic carboamination of terminal alkynes with benzyne and an archetypal O-benzoylhydroxylamine electrophile is presented. Probing various plausible pathways for relevant elementary steps and scrutinising performance degradation pathways, with the aid of a reliable computational protocol applied to a realistic catalyst model combined with kinetic analysis, identified the pathways preferably traversed in productive catalysis. It entails rapid alkynylcupration of in situ generated benzyne to deliver the arylcopper nucleophile that undergoes amination with the O-benzoylhydroxylamine electrophile to afford copper benzoate. Umpolung-enabled electrophilic amination favours a multistep SN2-type oxidative addition/N-C bond-forming reductive elimination sequence involving a short-lived formal {P^P}CuIII carboxylate amido aryl intermediate. SN2-type displacement of the benzoate leaving group at the arylcopper nucleophile, which represents the catalyst resting state, is predicted to be the turnover limiting step. Alkynolysis transforms copper benzoate back to catalytically competent alkynylcopper. The computational probe of a wider range of substrates reveals that only severely ring-strained C6-arynes, C6-cycloalkynes and electron-deficient cyclopropenes featuring a highly reactive C≡C linkage could replace benzyne. Moreover, strict control of stationary benzyne concentration is indispensable for electrophilic carboamination to ever become achievable.

Стационарная вращательно-симметричная конвекция при изотахофорезе в круговой цилиндрической области с недеформируемой свободной непроницаемой боковой поверхностью

The results of a study of the isotachophoresis process convective stability are presented. Isotachophoresis is the method of separation of a multicomponent mixture to individual components by an external electric field. It is assumed that the process of isotachophoresis occur in an infinite vertical circular cylinder with free side boundaries. The problem of the stationary (monotonic, neutral) concentration gravitational convection occurrence is transform to the study of the solution stability for the problem linearized on the solution of the original problem corresponding to the mechanical equilibrium of the final stage of the isotachophoresis process, in which the zones of the individual components of the mixture move with the identical constant velocity in a stationary flow. It is indicated that the main contribution to the stability/instability of the equilibrium is made by concentration gradients in the vicinity of the boundaries between the zones of individual components. Due to the complexity of constructing an exact solution corresponding to mechanical equilibrium, the exact solution replaced by an asymptotic solution (piecewise constant concentration distribution), which, in turn, is an exact solution of the asymptotic version of the transport under action of an electric field component equations (diffusion-free model). The choice of piecewise constant mechanical equilibrium leads to concentration gradients in the form of delta functions and a linear boundary value problem with delta-like coefficients to determine the critical parameters of instability. An exact solution of the problem (a system of ordinary differential equations with boundary conditions) and, using the method of one-dimensional perturbations, an exact dispersion relation for determining critical parameters (in the case of vanishingly small diffusion) is constructed.

Regulatory effect of bacterial melanin on the isoforms of new superoxide-producing associates from rat tissues in rotenone-induced Parkinson’s disease

According to recent research, selective neuronal vulnerability in Parkinson’s disease (PD) results from several phenotypic traits, including calcium-dependent, feed-forward control of mitochondrial respiration leading to elevated reactive oxygen species and cytosolic calcium concentration, an extensive axonal arbor, and a reactive neurotransmitter. Therefore, antioxidant therapy is a promising direction in the treatment of PD. In vitro studies have indicated the survival-promoting activity of bacterial melanin (BM) on midbrain dopaminergic neuron cultures. It has been established that BM has a number of protective and anti-inflammatory properties, so there is a high probability of a protective effect of BM in the early stages of PD. In this study, PD was induced through the unilateral intracerebral administration of rotenone followed by bacterial melanin. Tissues (brain, lungs, and small intestine) from the observed groups underwent isolation and purification to extract isoforms of new thermostable superoxide (О2−)-producing associates between NADPH-containing lipoprotein (NLP) and NADPH oxidase-Nox (NLP-Nox). The optical absorption spectral characteristics, specific amounts, stationary concentration of the produced О2−, and the content of NADPH in the observed associates were determined. The optical absorption spectra of the NLP-Nox isoforms in the visible and UV regions in the experimental groups did not differ from those of the control group. However, compared with the control group, the specific content of the total fractions of NLP-Nox isoforms associated with PD groups was higher, especially in the small intestine. These findings suggest that the described changes may represent a novel mechanism for rotenone-induced PD. Furthermore, bacterial melanin demonstrated antioxidant properties and regulated membrane formation in the brain, lung, and small intestine. This regulation occurred by inhibiting the release of new membrane-bound formations (NLP-Nox associates) from these membranes while simultaneously regulating the steady-state concentration of the formed О2−.

Сравнение двух типов подвижных фаз для определения витаминов группы В методом тонкослойной хроматографии

Thin-layer chromatography (TLC) has been used to study the influence of a number of factors (the nature of the stationary phase, the nature and concentration of the organic solvents and surfactants, the pH of the buffer solution) on the chromatographic characteristics of B vitamins: B 1 (thiamine), B6 (pyridoxine), B12 (cyanocobalamin). The stationary phases were plates with polar (Sorbfil on a polymer (highperformance plates, HTLC) and aluminum substrates), weakly polar (Polyamide-6), and nonpolar (RP-18 on an aluminum substrate) sorbents. As micellar mobile phases – micellar solutions of cetylpyridinium chloride in the concentration range 5–10-4 – 5–10-1 M, sodium dodecyl sulfate in the concentration range 2,5–10-4 – 5–10-1 М. It has been established that among aqueous-organic mobile phases (MF) the best results have been obtained for MF of the composition acetonitrile – water (15:385) on polar high-performance plates. More effective than acetonitrile – water is the PF of the composition acetonitrile – cetylpyridinium chloride (15:85) in the presence of a phosphate buffer solution with pH = 3. For the last PF, TLC determination of vitamins B1, B6, B12 in pharmaceutical preparations with a Sr value of interval 0.01–0.06 has been developed.

Stationary concentration of 1O2 over 1O2 quantum yield: Next level of photoactivity analysis

The investigation of the activity of photosensitizers is a multivariate challenge for their further application in photocatalysis. Porphyrins are attractive photoactive molecules for chemical and biochemical applications, while their observed photocatalytic efficiency is a function of a variety of characteristics. In the present work the influence of porphyrin substituents on their photoactivity and photostability along with the solvent effect were studied and discussed in details. Series of experiments with 9,10-diphenylanthracene (DPA) as a selective 1O2 trap allowed to develop the approach for direct measurement of [1O2] and quantitatively evaluate the influence of various factors onto it. The processes of 1O2 relaxation, as well as its chemical and physical quenching were separated and analyzed individually. A kinetic scheme for the photosensitization process was treated with steady-state approximation to develop a mathematical apparatus, where a non-linear dependence between photosensitizer and singlet oxygen concentration was found. The general character of the derived non-linear dependence was proved experimentally for each studied porphyrin. Physical and chemical quenching rate constants of the studied porphyrins were calculated. DFT calculations allowed to find an empirical correlation between HOMO energies and observed rate constants. A plausible reaction mechanism between TPP and 1O2 was examined with Fast-NEB-TS method.

Alignment interaction and band formation in assemblies of autochemorepulsive walkers.

Chemotaxis refers to the motion of an organism induced by chemical stimuli and is a motility mode shared by many living species that has been developed by evolution to optimize certain biological processes such as foraging or immune response. In particular, autochemotaxis refers to chemotaxis mediated by a cue produced by the chemotactic particle itself. Here, we investigate the collective behavior of autochemotactic particles that are repelled by the cue and therefore migrate preferentially towards low-concentration regions. To this end, we introduce a lattice model inspired by the true self-avoiding walk which reduces to the Keller-Segel model in the continuous limit, for which we describe the rich phase behavior. We first rationalize the chemically mediated alignment interaction between walkers in the limit of stationary concentration fields, and then describe the various large-scale structures that can spontaneously form and the conditions for them to emerge, among which we find stable bands traveling at constant speed in the direction transverse to the band.

Reconsidering Dogmas about the Growth of Bacterial Populations.

The growth of bacterial populations has been described as a dynamic process of continuous reproduction and cell death. However, this is far from the reality. In a well fed, growing bacterial population, the stationary phase inevitably occurs, and it is not due to accumulated toxins or cell death. A population spends the most time in the stationary phase, where the phenotype of the cells alters from the proliferating ones, and only the colony forming unit (CFU) decreases after a while, not the total cell concentration. A bacterial population can be considered as a virtual tissue as a result of a specific differentiation process, in which the exponential-phase cells develop to stationary-phase cells and eventually reach the unculturable form. The richness of the nutrient had no effect on growth rate or on stationary cell density. The generation time seems not to be a constant value, but it depended on the concentration of the starter cultures. Inoculations with serial dilutions of stationary populations reveal a so-called minimal stationary cell concentration (MSCC) point, up to which the cell concentrations remain constant upon dilutions; that seems to be universal among unicellular organisms.

О конвективной устойчивости равновесия коллоидов и жидких бинарных смесей при положительной термодиффузии

The study investigates stability of the mechanical equilibrium of colloids and binary mixtures with positive thermal diffusion. Such problems are usually considered in the presence of a stationary con-centration distribution that arises due to thermal diffusion and (or) sedimentation. But in connected vertical channels of a square section of 3.2 × 3.2 mm with a height of 50 mm, a Hele-Shaw cell of 17 × 32 × 1.5 mm, and a flat layer with a height of 3mm when heated from below, the time it takes the concentration profile to become settled is extremely long and ranges from several days to several years. Therefore, the stability of the equilibrium was analyzed in the presence of increasing concen-tration inhomogeneities. This helped explain the experimental facts: 1) periodic (~ 4 hours) convec-tive bursts were observed in the magnetic fluid in channels below the critical Rayleigh number; 2) bursts with a period of ~ 0.5 hours were observed in the binary mixture in the Hele-Shaw cell. A formula for the period of bursts has been obtained, it gives results close to experimental ones.

Superoxide-producing thermostable associate from the small intestines of control and alloxan-induced diabetic rats: quantitative and qualitative changes

Background:NADPH oxidase 1 (Nox1), which is highly expressed in the colon, is thought to play a potential role in host defense as a physical and innate immune barrier against commensal or pathogenic microbes in the gastrointestinal epithelium. Diabetes can be caused by several biological factors, including insulin resistance is one of them. Alloxan is widely used to induce insulin-dependent diabetes in experimental animals. Alloxan increases the generation of reactive oxygen species as a result of metabolic reactions in the body, along with a massive increase in cytosolic calcium concentration.MethodsUsing a universal method, a superoxide radical (О2−)-thermostable associate between NADPH-containing lipoprotein (NLP) and NADPH oxidase (Nox)- NLP-Nox was isolated and purified from the small intestine (SI) of control (C) and alloxan-induced diabetic (AD) albino rats.ResultsIn comparison to the C indices, in AD in the SI, an increase in the specific content of NLP-Nox associate and a decrease in the stationary concentration of produced О2− in liquid phase (in solution) and gas phase (during blowing by oxygen of the NLP-Nox solution) were observed. The NLP-Nox of SI associate in C and AD rats produced О2− by an immediate mechanism, using NLP as a substrate. The phenomenon of the hiding of the optical absorption maxima of the Nox in oxidized states at pH10,5 was observed in the composition of these SI associates of the C and AD rat groups. The characteristic absorption maxima of the «hidden» Nox were observed under these conditions after reduction by potassium dithionite.ConclusionThus, at AD, the decrease in the stationary concentration of produced О2− in the solution and gas phase was compensated for by an increase in the specific amount of associate. In addition, the decrease in the stationary concentration of produced О2− by NLP-Nox associates at AD can be linked to a decrease in the level of NADPH in NLP-Nox composition. This could be used as a new mechanism of AD pathogenesis.

Superoxide-producing thermostable complex from plant foods: isolation, purification and properties

From Armenian plant food – tomato (Solanum lycopersicum esculentum), carrot (Daucus carota subsp. sativus), green bean (Phaseolus vulgaris) and potato (Solanum tuberosum), the isoforms of superoxide (О2) producing complexes between NADPH containing protein component (NPC) and Fe(III) – NPC-Fe(III), were isolated and purified for the first time. At the same time, the fractionation of these complexes at pH 9,5 and 4,8 were carried out [1]. The isoforms of NPC-Nox are high thermostable biosystems (up to 100oC). The immediately mechanism of the production of О2 by these complexes, due to the transfer of the electron from NPC to the Fe(III), then to О2 for its reduction up to О2 was conditioned. As a substrate for NPC-Fe(III) is not free NADPH, but NADPH is connected with the protein component (PC). The forms of optical absorption spectra of these complexes in visible region essentially were differed, although, in UV region the characteristic for the proteins maximal optical absorption at 260-280 nm were observed. The higher specific content (mg/g) for complexes from tomato, than from carrot, green bean and potato were observed. The direct proportional dependence between the content of the NADPH in the composition of NPC and stationary concentration of produced О2 in homogenous phase (in solution) and gas phase were presented. The isolated NPC from indicated above complexes, at the expense of NADPH, only the reductive (antioxidant) effect was indicated and was activated the NADPH oxidase (Nox) in vitro, in particular from erythrocytes membranes (ЕМ) аnd leukocytes membranes (LM). By the blowing of the slightly opalescent aqueous solutions of these complexes with oxygen the gas phase О2 were produced, which were transferred oxygen through the silicone or glass tubes.

Predictive modeling and experimental implementation of organic acids in stream recovery by reactive extraction in membrane contactors

• Substantial reduction of acid accumulation with the coupled process. • Great viscosity variations due to the transfer. • Viscosity changes successfully taken into account to describe kinetics. • Model-based generalization for process guidelines. Membrane-based reactive extraction as an in situ product recovery technique is a promising strategy for process intensification, in particular in the case of the bioproduction of organic acids. Reactive extraction allows a high selectivity for the extraction of the targeted acid and the microporous membrane keeps biocatalysts in the aqueous broth while implementing a large liquid–liquid surface area and ensuring a dispersion-free contact, without problems of emulsion formation. This paper deals specifically with the extraction of biobased 3-hydroxypropionic acid using tri- n -octylamine in n -decanol. In order to maintain an effective driving force for 3-HP transfer into the organic phase, this latter was continuously regenerated by recovering the acid in a back-extraction aqueous phase, giving a complete pertraction process. A mass transfer model for this process was developed. It is based on the boundary layer theory and takes into account chemical and physical equilibria of complexation/dissociation and partitioning, species diffusion in the membrane pores and viscosity variations in the organic phase. Viscosity highly depends on acid concentration, increasing up to 50% when 3-HP concentration reaches 28 g.L -1 . Thus, it was possible to predict different experimental results with R 2 ≥ 0.99, totally neglecting chemical kinetics and interfacial resistance for both extraction and back-extraction steps. The model allows the prediction of extraction kinetics with (1) fixed initial concentrations and (2) with gradual 3-HP feed (mimicking a bioconversion) in transient and steady states coupled with back-extraction (globally also called pertraction). Model based analysis of mass transfer mechanisms led to the construction of a nomogram giving 3-HP stationary concentration in the case of a typical production rate, enabling for example a rapid organic phase selection or membrane sizing.

Longitudinal assessment of personal air pollution clouds in ten home and office environments.

Elevated exposure to indoor air pollution is associated with negative human health and well-being outcomes. Inhalation exposure studies commonly rely on stationary monitors in combination with human time-activity patterns; however, this method is susceptible to exposure misclassification. We tracked ten participants during five consecutive workdays with stationary air pollutant monitors at their homes and offices, and wearable personal monitors. Real-time measures of size-resolved particulate matter (within range 0.3-10μm) and CO2 , and integrated samples of PM10 , VOCs, and aldehydes were collected. The PM10 cloud magnitude (excess of PM10 beyond stationary room concentration) was detected for all participants in homes and offices. The PM10 cloud magnitude ranged within 5-37μg/m3 and was the most discernible in the coarse particle size fraction. Particles associated with "Urban mix," "Traffic," and "Human activities" sources contributed the most to PM10 exposures. The personal CO2 clouds were detected for participants with the SEMs in their living rooms and private or low-occupancy offices. The stationary monitors placed in bedrooms were better predictors of personal PM10 and CO2 exposures. An overall of 33VOCs and aldehydes were detected in both microenvironments, with the majority exhibiting high correlation between personal and stationary stations.

SIMULATION OF THE P-I-N-STRUCTURES CHARACTERISTICS INTERACTING WITH HIGH-FREQUENCY ELECTROMAGNETIC RADIATION BY PERTURBATION THEORY METHODS

The mathematical model is proposed for the electron-hole plasma characteristics predicting of the active region (i-region) of p-i-n structures, taking into account the effect of the displacement current (induced by an external microwave electromagnetic field) on the formation of a space charge. The model is based on a singularly perturbed nonlinear boundary value problem for the system of the electron-hole current continuity equations and Poisson’s (the Poisson’s equation contains a naturally formed small parameter). The model nonlinear boundary value problem is reduced to a recurrent sequence of linear boundary value problems for determining of the electron-hole plasma concentrations and the electric potential distributions in the i-region by using asymptotic methods, in particular, the boundary layer method and complex amplitudes. The proposed mathematical model feature is that it reflects the role of the boundary layer in the p-i-n structure contact zones in the formation of a space charge and takes into account the effect of a displacement current caused by microwave radiation. An algorithm for predicting the charge carrier concentrations distribution in the electron-hole plasma is constructed. It is shown that an extraneous microwave field entails an additional increase in the stationary concentration of electrons and holes in the active region, against which the plasma concentration fluctuates at the microwave field frequency (the appearance of higher harmonics is not taken into account in the model). The effect of the growth of the concentration stationary component is more pronounced in the zones of p-i-, n-i-contacts. The proposed mathematical model and the developed algorithm for analyzing the problem posed are important for developers of microwave electronics semiconductor elements, in particular, p-i-n structures used for switching powerful electromagnetic fields and as protective devices for the input paths of radio engineering systems.

The pathways of the phthalic anhydride selectivity and yield increase at C4-C5-hydrocarbons oxidation

The investigation of n-butane and n-pentane oxidation in system with two consecutive reactors confirmed the mechanism of phthalic anhydride formation by Diels-Alder reaction between maleic anhydride and C4 unsaturated hydrocarbons. The process is limited by low stationary concentration of C4 unsaturated hydrocarbons in reaction mixture which is connected with high rate of their oxidation to maleic anhydride. It was shown that n-butane oxidation leads to formation of maleic anhydride only but the introduction of unsaturated C4-hydrocarbons on inlet of the second catalytic reactor accompanied by phthalic anhydride appearance on outlet of these two consecutive reactors system. It was established that in case of 1,3-butene introduction in the second reactor the quantity of phthalic anhydride formed is more than in case of 2-butene addition. It was predicted that a decrease of the temperature in the second reactor can leads to an increase the phthalic anhydride selectivity and its yield as result of Diels-Alder reaction effectiveness. This assumption was confirmed by experimental results. In results the method of phthalic anhydride production by the use of two consecutive reactors was proposed. The summary yield of this product on this new process can reach up to 35 mol. %. In the case of n-pentane oxidation the formation of maleic and phthalic anhydrides was observed with excess of first product but the introduction of unsaturated C4-hydrocarbons in the inlet of second reactor leads to an increase of the phthalic anhydride concentration and its selectivity and yield. In result the yield of phthalic anhydride equal to 35 mol. % can be obtained. So, the proposed by us mechanism of phthalic anhydride was confirmed by new experimental results and other pathways for the selectivity and yield of this product can be predicted.

Building stationary gas emissions concentration fields in the areas impacted by non-ferrous metals producers

This paper looks at the gas emissions balance in the wind corridor along the wind direction. An equation was found that describes the dependence of the emissions concentration inside the wind corridor along the wind direction when the concentration inside the wind corridor at the right angle to the wind flow is uniform. The authors propose a system of diffusion equations and its solution in a quasi-steady state for determining the concentration field in the whole space. It is shown that the transfer distance ratio has an approximate correspondence to the diffusion scope in the overall concentration. The diffusion scope was found to not exceed 0.01 %. And it becomes even lower as the wind speed rises and the time interval extends for which the diffusion transfer is analyzed. That’s why the wind transfer process can serve as a sufficient factor of changing concentration. To create a mathematical image of the concentration field for a given pollutant in the geographical coordinates, apart from the emission intensity and the chemical activity of such pollutant in air, one needs to know the wind rose of the region where the production site is situated. This helps determine the relationship between the maximum concentration of the pollutant and the distance (from the source of emission) in eight geographical directions, in eight points of the wind rose. It is noted that the use of the wind rose for mapping full information on the distribution of each pollutant helps superpose the fields of the maximum allowable concentrations (maximum hazard) of each pollutant with the geographical map of a particular production site. A relationship was defined between the maximum concentration of the pollutant and the source of emissions. The paper also describes the results of a study that looked at the transfer of emissions in air and determined the maximum distance for the maximum allowable concentration of sulphur dioxide emitted by Nornickel’s Norilsk site. It is demonstrated that when a light northeast wind blows (the average speed is around 3 m/sec), the SO2 concentration in the northeast sector of the wind rose along the wind path is likely to exceed the maximum allowable mean daily concentration as far as 2,500 km from the site.

Numerical simulation of deflagration in hydrogen-air gas mixes

Verification of validity of different manifolds of chemical reactions and coefficients in Arrhenius formulae was made for numerical simulation of deflagration appearing in hydrogen-air gas mixes. Kinetic model of branching chain reaction was tested for initial stage of detonation of this kind of mixes. One dimensional numerical simulations of deflagration initiation where provided for small closed heat isolated region. The next problem was solved numerically:in small closed volume, initially filled by hydrogen-air mix with atmospheric meanings of gas dynamics parameters at moment t=0 temperature rising till meaning, at which reaction of deflagration should begin. Numerical experiment consist of calculation of thermodynamics parameters of gas mix in small isolated volume. Meanings of molar concentration of components of gas mix where calculated by implicit numerical method of Gir for numerical decision. Calculation where provided till zero concentration of hydrogen or not appearing of deflagration at all. Characteristic feature of hydrogen-air gas mix deflagration is appearance of sudden explosion after long period of induction. In this induction period grows of radicals H, O and OH appears. Mass of radicals, nevertheless stay small, and one radical component transverse to the others. This explosion mechanism is branching chain reaction introduced by N.N.Semenov. In agreement with branching chain reaction theory during process of branching chain reaction radicals H, O, OH many times initiates reaction with other components of the mix. Nevertheless mass of radical components preserve small during the reaction, them almost fully disappeared in every time of the process. That’s why method of “quasi - stationary concentration” is treated to components O, OH (velocity of changing of this components concentration is equal to zero). For concentration of component H one simplified differential equation is treated. Speed of changing H essentially grater then speed of changing “slow” components H2, O2, H2O, that’s why equation for H should be solved separately. Algorithm was developed for numerical simulation of hydrogen-air mixes on the basis of theory branching chain reactions. Calculations provided demonstrate applicability of developed algorithm for numerical simulations of initial stage of deflagration of hydrogen-air mixes.

Numerical exploration of first-order relativistic hydrodynamics

We present the first numerical solutions of the causal, stable relativistic Navier-Stokes equations as formulated by Bemfica, Disconzi, Noronha, and Kovtun (BDNK). For this initial investigation we restrict to plane-symmetric configurations of a conformal fluid in Minkowski spacetime. We consider evolution of three classes of initial data: a smooth (initially) stationary concentration of energy, a standard shock tube setup, and a smooth shockwave setup. We compare these solutions to those obtained with the Muller-Israel-Stewart (MIS) formalism, variants of which are the common tools used to model relativistic, viscous fluids. We find that for the two smooth initial data cases, simple finite difference methods are adequate to obtain stable, convergent solutions to the BDNK equations. For low viscosity, the MIS and BDNK evolutions show good agreement. At high viscosity the solutions begin to differ in regions with large gradients, and there the BDNK solutions can (as expected) exhibit violation of the weak energy condition. This behavior is transient, and the solutions evolve toward a hydrodynamic regime in a way reminiscent of an approach to a universal attractor. For the shockwave problem, we give evidence that if a hydrodynamic frame is chosen so that the maximum characteristic speed of the BDNK system is the speed of light (or larger), arbitrarily strong shockwaves are smoothly resolved. Regarding the shock tube problem, it is unclear whether discontinuous initial data is mathematically well-posed for the BDNK system, even in a weak sense. Nevertheless we attempt numerical solution, and then need to treat the perfect fluid terms using high-resolution shock-capturing methods. When such methods can successfully evolve the solution beyond the initial time, subsequent evolution agrees with corresponding MIS solutions, as well as the perfect fluid solution in the limit of zero viscosity.