Визуализация потока воздуха в вихревой трубе с использованием различных моделей турбулентности

Visualization of air flow in Ranque-Hilsch vortex tube performed by numerical simulations with standard k-ε and SAS-SST turbulence models is presented in the paper. SAS-SST turbulence model predicted the existence of secondary largescale vortex structures within the computational domain instead k-ε model showed axisymmetrical flow. Existence of large-scale secondary vortex structures is in agreement with experimental data.В статье представлены результаты визуализации потока воздуха в вихревой трубе Ранка-Хилша, выполненной с помощью численного моделирования. Были использованы k-ε и SAS-SST модели турбулентности. SAS-SST модель турбулентности показала наличие вторичных крупномасштабных вихревых структур в расчетном домене, в отличие от k-ε модели. Факт наличия крупномасштабных вторичных вихревых структур хорошо согласуется с экспериментальными данными

Hydrobionts of a freshwater oil-polluted northern lake: bioaccumulation of heavy metals in fish and the rate of ecosystem recovery

The response of phytoplankton, zooplankton, benthic and fish community structure to one of the biggest oil spill in history of Komi Republic (north-west part of Russia) was investigated using data from a long-term survey off the polluted lake. The characteristics of aquatic freshwater communities observed in the study area 10, 11 and 22 years after the spill (1994) were compared to find out the rate of natural recovery of the ecosystem after oil decontamination of bottom sediments. The concentrations of fifteen trace metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Pb, U, Bi, Th) were analyzed in the tissues (muscle) of three fish species. The concentrations of Al (3-309 mg/kg), Cr (0,1-3,71 mg/kg), Fe (8,6-317 mg/kg), and Cu (0,09-99 mg/kg) in fishes from polluted lake resulted in most cases higher than reference thresholds. Quantitative and qualitative indicators of aquatic invertebrates from polluted lake reach those one of unpolluted lake but do not fully recover 22 years after the spill, despite that oil concentration in water column and in bottom sediments was lower than reference tresholds. We conclude that natural recovery rate of aquatic freshwater ecosystems in northern regions after oil pollution is extremely low. The purification of water and bottom sediments of oil-polluted northern water bodies is necessary for stimulation of ecosystem restoration

Studies of Catalytic Properties of Inorganic Rock Matrices in Redox Reactions

Intrinsic catalytic properties of mineral matrices of various kinds (basalts, clays, sandstones) were studied, which are of interest for in-situ heavy oil upgrading (i.e., underground) to create advanced technologies for enhanced oil recovery. The elemental, surface and phase composition and matrix particle morphology, surface and acidic properties were studied using elemental analysis, X-ray diffraction, adsorption and desorption of nitrogen and ammonia. The data on the catalytic activity of inorganic matrices in ammonium nitrate decomposition (reaction with a large gassing), oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltenes into maltenes (the conversion of heavy hydrocarbons into more valuable light hydrocarbons) were discussed. In order to check their applicability for the asphaltenes hydrocracking catalytic systems development, basalt and clay matrices were used as supports for iron/basalt, nickel/basalt and iron/clay catalysts. The catalytic activity of the matrices in the reactions of the decomposition of ammonium nitrate, oxidation of hydrocarbons and carbon monoxide, and hydrocracking of asphaltens was observed for the first time

Effect of the divergence of a relativistic electron beam on the diffracted transition radiation excited by them in a single-crystal target

The dependence of the angular density and the photon yield of collimated diffracted transition radiation (DTR) generated in a thin single-crystal plate by a beam of relativistic electrons on the beam divergence are studied. An expression describing the DTR angular density averaged over all the rectangular trajectories of electrons in the beam is derived. For the averaging, the two-dimensional Gaussian distribution is used. A significant dependence of the angular density of collimated DTR photons on the electron-beam divergence is shown. An expression describing the number of collimated DTR photons is obtaine

Determining the divergence of an ultra-relativistic electron beam from the diffracted transition radiation in a single-crystal target

We have studied the possibilities of using diffracted transition radiation excited by a relativistic electron beam in a single-crystal target to determine the beam divergence. For this purpose, we investigated the expressions we had previously derived that describe the angular density of diffracted transition radiation excited by a relativistic electron beam crossing a thin single-crystal plat

Diffracted transitive radiation as a means for indicating the divergence of an ultrarelativistic electron beam

Results of model calculations of the electron beam divergence parameters for a given yield of DTR photons traversing the slit collimator have shown that the formula proposed in this work can be successfully used as a basis for the development of methods for measuring the divergence of ultrahigh-energy relativistic electron beams based on the angular DTR distributio

The problem of osteoarthritis of the knee joint and running through the prism of magnetic resonance tomography

The number of women and the elderly has now increased among marathon runners. This cohort has a high risk of osteoarthritis development. The hypothesis, based on little scientific evidence, is that the additional stress on knee joints that occurs during long running can potentially lead to damage to joint structures and osteoarthritis development. The review presents modern generalized data on magnetic resonance imaging (MRI) of knee joints in long-distance runners. Special attention is paid to the syndrome of fluid increase in subchondral bone, which is determined by increasing the signal intensity in T2-weighted images (decrease in T1-weighted images), called bone marrow oedema (BMO). Classification and pathogenetic variants of BMO development (theory of intrusion and contusion) are presented. Particular cases of BMO development in marathon runners are considered. The dynamics of BMO in different time intervals after the races in beginners and professional marathon runners is described. Changes in MRI images of knee cartilage after running on the treadmill in healthy women and in women suffering from osteoarthritis are shown. A comparison of the frequency of osteoarthritis of knee joints in runners compared to footballers and weightlifters was made. The conclusion was made on the preventive effect of long walking and running (at least 12.5 km/week), including marathon distances, on the development and progression of osteoarthritis of knee joints

On the problem of application of diffracted transition radiation for indication of relativistic electron beam parameters

The model calculations of the electron beam divergence parameters on the base of “measured” yield of DTR photons traversing through a slit collimator are carried out. The results of the calculation show that the proposed in this work formula can be successfully used as a base for the development of methods for measuring the divergence of beams of relativistic ultrahigh-energy electrons based on DTR angular distributio

THE SIGNIFICANCE OF C‑REACTIVE PROTEIN IN SYSTEMIC LUPUS ERYTHEMATOSUS

It is believed that the concentration of C‑reactive protein (CRP) significantly increases in acute forms of systemic lupus erythematosus (SLE). A moderate increase of CRP levels in patients with stable disease progression reflects the low‑grade chronic inflammation in the vascular wall and the development of subclinical atherosclerosis. The article presents data showing that increased CRP levels in SLE patients is not statistically related with disease activity and cardiovascular risk as well as the level of interleykin‑6. Patients with lupus nephritis have lower CRP concentration compared to patients without renal disease and CRP concentration depends on proteinuria and hypoalbuminemia.</p