Theory of pattern-formation of metallic microparticles in poorly conducting liquid

We develop continuum theory of self-assembly and pattern formation in metallic microparticles immersed in a poorly conducting liquid in DC electric field. The theory is formulated in terms of two conservation laws for the densities of immobile particles (precipitate) and bouncing particles (gas) coupled to the Navier-Stokes equation for the liquid. This theory successfully reproduces correct topology of the phase diagram and primary patterns observed in the experiment [Sapozhnikov et al, Phys. Rev. Lett. v. 90, 114301 (2003)]: static crystals and honeycombs and dynamic pulsating rings and rotating multi-petal vortices.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Velocity Distributions of Granular Gases with Drag and with Long-Range Interactions

We study velocity statistics of electrostatically driven granular gases. For two different experiments: (i) non-magnetic particles in a viscous fluid and (ii) magnetic particles in air, the velocity distribution is non-Maxwellian, and its high-energy tail is exponential, P(v) ~ exp(-|v|). This behavior is consistent with kinetic theory of driven dissipative particles. For particles immersed in a fluid, viscous damping is responsible for the exponential tail, while for magnetic particles, long-range interactions cause the exponential tail. We conclude that velocity statistics of dissipative gases are sensitive to the fluid environment and to the form of the particle interaction.Comment: 4 pages, 3 figure

Interacting circular nanomagnets

Regular 2D rectangular lattices of permalloy nanoparticles (40 nm in diameter) were prepared by the method of the electron lithography. The magnetization curves were studied by Hall magnetometry with the compensation technique for different external field orientations at 4.2K and 77K. The shape of hysteresis curves indicates that there is magnetostatic interaction between the particles. The main peculiarity is the existence of remanent magnetization perpendicular to easy plain. By numerical simulation it is shown, that the character of the magnetization reversal is a result of the interplay of the interparticle interaction and the magnetization distribution within the particles (vortex or uniform).Comment: 16 pages, 8 figure

Cellular Models for River Networks

A cellular model introduced for the evolution of the fluvial landscape is revisited using extensive numerical and scaling analyses. The basic network shapes and their recurrence especially in the aggregation structure are then addressed. The roles of boundary and initial conditions are carefully analyzed as well as the key effect of quenched disorder embedded in random pinning of the landscape surface. It is found that the above features strongly affect the scaling behavior of key morphological quantities. In particular, we conclude that randomly pinned regions (whose structural disorder bears much physical meaning mimicking uneven landscape-forming rainfall events, geological diversity or heterogeneity in surficial properties like vegetation, soil cover or type) play a key role for the robust emergence of aggregation patterns bearing much resemblance to real river networks.Comment: 7 pages, revtex style, 14 figure

The influence of defects on magnetic properties of fcc-Pu

The influence of vacancies and interstitial atoms on magnetism in Pu has been considered in frames of the Density Functional Theory (DFT). The relaxation of crystal structure arising due to different types of defects was calculated using the molecular dynamic method with modified embedded atom model (MEAM). The LDA+U+SO (Local Density Approximation with explicit inclusion of Coulomb and spin-orbital interactions) method in matrix invariant form was applied to describe correlation effects in Pu with these types of defects. The calculations show that both vacancies and interstitials give rise to local moments in $f$-shell of Pu in good agreement with experimental data for annealed Pu. Magnetism appears due to destroying of delicate balance between spin-orbital and exchange interactions.Comment: 13 pages, 4 figure

Регрессия саркомы Капоши после длительного лечения ингибиторами m-TOR и полной отмены иммуносупрессии у реципиента после трансплантации почки

A case of observation of a patient who developed Kaposi’s sarcoma after kidney transplantation is presented. For the purpose of its treatment, conversion from tacrolimus to everolimus, courses of administration of prospidin were applied, in General, the intensity of immunosuppressive therapy was reduced. Stable remission was achieved only after removal of the renal transplant and complete withdrawal of immunosuppressive therapy.Представлен случай наблюдения пациента, у которого после трансплантации почки развилась саркома Капоши. С целью ее лечения были применены конверсия с такролимуса на эверолимус, курсы введения проспидина, в целом уменьшена напряженность иммуносупрессивной терапии. Устойчивая ремиссия достигнута лишь после удаления почечного трансплантата и полного отказа от иммуносупрессивной терапии

A hysteresis model with dipole interaction: one more devil-staircase

Magnetic properties of 2D systems of magnetic nanoobjects (2D regular lattices of the magnetic nanoparticles or magnetic nanostripes) are considered. The analytical calculation of the hysteresis curve of the system with interaction between nanoobjects is provided. It is shown that during the magnetization reversal system passes through a number of metastable states. The kinetic problem of the magnetization reversal was solved for three models. The following results have been obtained. 1) For 1D system (T=0) with the long-range interaction with the energy proportional to $r^{-p}$, the staircase-like shape of the magnetization curve has self-similar character. The nature of the steps is determined by interplay of the interparticle interaction and coercivity of the single nanoparticle. 2) The influence of the thermal fluctuations on the kinetic process was examined in the framework of the nearest-neighbor interaction model. The thermal fluctuations lead to the additional splitting of the steps on the magnetization curve. 3) The magnetization curve for system with interaction and coercivity dispersion was calculated in mean field approximation. The simple method to experimentally distinguish the influence of interaction and coercivity dispersion on the magnetization curve is suggested.Comment: 22 pages, 8 figure

Доплеровский артефакт мерцания: физические механизмы и место в диагностической практике. Современное состояние вопроса

The twinkling artifact has been known to specialists in ultrasound diagnostics since 1996. However, until now there is no understanding of the reasons for its appearance, and the place of its application in diagnostics.Material and methods. Electronic databases (PubMed, E-library, Web of Science) were searched studies using the keyword – “twinkling artifact”. The scientific publications on the Doppler twinkling artifact from the moment of the first reports about its existence is systematized and analyzed. The authors' own developments on this topic are presented. Modern views on this phenomenon and its place in ultrasound diagnostics are described. An explanation of the physical mechanisms of this phenomenon is given.Results. Recommendations are formulated for practitioners on changing the settings of an ultrasound scanner in order to increase twinkling artifact detectability. The directions of using the artifact to obtain additional diagnostic signs of pathological changes, which currently include the diagnosis of nephro-, uretero- and choledocholithiasis, are determined.Conclusions. The high efficiency of the use of the twinkling artifact for the diagnosis of small kidney stones, comparable with the capabilities of computed tomography, has been shown.  Введение. Артефакт мерцания известен специалистам ультразвуковой диагностики с 1996 г. Однако до настоящего времени нет однозначного понимания как физических основ его появления, так и областей ультразвуковой диагностики, где выявление его несет реальную диагностическую информацию.Материал и методы. В электронных базах данных (PubMed, E-library, Web of Science) был проведен поиск опубликованных исследований по ключевым словам “twinkling artifact”, “мерцающий артефакт”, “артефакт мерцания”. Систематизирована и проанализирована имеющаяся научная литература, посвященная доплеровскому артефакту мерцания с момента первых публикаций о его существовании. Отмечены собственные разработки на эту тему. Определены современные взгляды на данное явление и его место в ультразвуковой диагностике. Представлена основная на настоящий момент версия о причинах возникновения данного явления.Результаты. Сформулированы рекомендации для практических врачей по изменению настроек ультразвукового сканера с целью повышения выявляемости артефакта мерцания. Определены направления использования артефакта для получения дополнительных диагностических признаков патологических изменений, к которым в настоящее время относят диагностику нефро-, уретеро- и холедохолитиаза.Заключение. Отмечена высокая эффективность использования артефакта мерцания для диагностики мелких камней почек, сопоставимая с возможностями компьютерной томографии. Показана низкая результативность использования артефакта для выявления микрокальцинатов молочной железы и обызвествлений других анатомических структур

Meglumine Sodium Succinate to Correct COVID-19-Associated Coagulopathy: the Feasibility Study

Aim of the study: to evaluate the effect of meglumine sodium succinate (MSS) on the efficacy of anticoagulant therapy in patients with severe COVID-19 infection complicated by bilateral community-acquired pneumonia.Materials and methods. Overall efficacy of treatment was analyzed in 12 patients hospitalized to ICU with the diagnosis of severe confirmed COVID-19 coronavirus infection (U07.1) complicated by bilateral multisegmental pneumonia. All patients received prophylactic anticoagulation with unfractionated heparin. The patients were divided into two groups: 7 of them received a multi-electrolyte solution containing MSS 5 ml/kg daily for the entire ICU stay (3-10 days) as a part of therapy; 5 patients received a similar volume of a conventional multi-electrolyte solution containing no metabolically active substrates and comprised a control group. Coagulation parameters were measured in arterial and venous blood of all patients at the following stages: 1) upon admission to the ICU; 2) 2-4 hours after the first dose of heparin; 3) 8-12 hours after the second dose of heparin; 4) 24 hours after the beginning of intensive therapy. On the 28th day of follow-up, mortality, duration of ICU stay, and incidence of thrombotic complications in the groups were evaluated. Nonparametric methods of statistical analysis were used to assess intragroup changes and intergroup differences.Results. The group of patients administered with MSS had significantly fewer thromboembolic events during 28 days of treatment and shorter ICU stay. These patients responded faster to anticoagulant therapy, which was suggested by more distinct changes in coagulation parameters, i.e. increased APTT, persisting viable thrombocyte population, reduced D-dimer and fibrinogen levels.Conclusion. The metabolic action of succinate possibly increases endothelial resistance to damaging factors and reduces its procoagulant activity. The hypothesis requires testing in a larger clinical study with a design including laboratory evaluation of the efficacy of varying doses of the studied drug as well as aiming at elucidation of the mechanisms of its effect on specific pro- and anticoagulation system components

Human NK cells internalize recombinant major stress protein HSP70

Heat shock proteins 70 kDa (HSP70) protect intracellular proteins from the damaging effects of stress factors of various natures. Moreover, HSP70 play an important role in the vital activity of cells under normal physiological conditions, performing chaperone functions. These functions are realized in the intracellular space; however, in some cases, these proteins are also found on the cell surface and in the extracellular environment. The causes and mechanisms of HSP70 translocation to the cell surface and secretion into the extracellular space have not yet been well understood, but such an unusual localization of HSP70 activates the immune system. The surface HSP70 and their extracellular pool stimulate the cytotoxic activity of NK cells. However, direct experimental evidence for the internalization of HSP70 molecules by NK cells has not yet been demonstrated. This paper presents the results of the interaction of the extracellular HSP70 pool with NK cells from the peripheral blood. The results demonstrated the confirmation of the internalization of exogenous HSP70 molecules by NK cells. To this end, fluorescently labeled recombinant stress-inducible human HSP70 were obtained. The electrophoretic data indicated the absence of protein degradation during the labeling process, the purity and stability of the modified protein. To assess the interaction of HSP70 with NK cells, the fluorescently labeled HSP70 was added to an in vitro culture of NK cells isolated by magnetic separation from the peripheral blood mononuclear fraction and analyzed by confocal microscopy. This analysis indicated that living NK cells internalize extracellular HSP70 with localization both in lysosomes and in phagosomes. Our experiments illustrated for the first time the process of penetration of the extracellular form of HSP70 into these cells. The results suggest that the activation of NK cells under the action of exogenous HSP70 could be associated with the internalization of these protein molecules