Slow and fast magneto-optical response of magnetite nanoparticles suspension

DC magnetic field applied to Fe3O4 nanoparticle suspension affects its light scattering. Time dependent variations in the light intensity transmitted through a suspension are observed after the magnetic field is switched-on. Two types of variations can be distinguished. Fast response takes less than millisecond while slow variations occur at the time interval from seconds to hundreds of minutes. Possible mechanisms of these variations are discussed

Optical and photoluminescent properties of nanostructured hybrid films based on functional fullerenes and metal nanoparticles

The chemically cross-linked C₆₀ thin films, capable of binding Ag or Au nanoparticles, were prepared by the gas-phase treatment with diamine for one set of samples and dithiol for another one and decoration with Ag or Au nanoparticles, respectively. The optical and photoluminescent properties of the obtained nanostructured hybrid films in comparison with the undecorated films were studied. The low temperature photoluminescence (PL) spectra demonstrate significant changes of the band intensity and appearance of fine structure for bands connected with radiative transitions of self-trapped and localized excitons. The decoration of pristine and treated C₆₀ films with Ag nanoparticles leads to a decrease of PL intensity and to slight bandgap reduction. These phenomena can be explained by the increase of the surface recombination velocity at the fullerene-nanoparticle interface. At the same time, the nanoparticles insignificantly decrease the transmittance of light into the fullerene and Si layers, and have almost no influence on photoelectric properties of metal/fullerene/Si barrier structures

Антимутагенная активность лекарственных растений Сибирского региона

The antimutagenic activity of 41 Siberian herbs has been studied with microcores analysis method (calculation of micronucleous erythrocyte number in peripheral blood of mice). The most active species have been composed in herb preparations and the preparation with the most activity has been revealed with microcores analysis method. The microcore number decrease has been observed up to 1,80‰. Antimutagenic herb preparation activity is defined by the content of vitamins, pigments, coumarins, polyphenol complex, flavonoids, terpenic saponins, lactones and other compounds.Методом микроядерного анализа — подсчета количества эритроцитов с микроядрами в периферической крови мышей — была изучена антимутагенная активность 41 растения Сибири. Из наиболее активных видов были составлены растительные сборы, методом микроядерного анализа выявлен сбор с наибольшей активностью. Наблюдаемое снижение числа микроядер доходило до 1,80‰. Антимутагенная активность препаратов из растений обусловлена содержанием витаминов, пигментов, кумаринов, полифенольного комплекса, флавоноидов, терпеновых сапонинов, лактонов и других веществ

Features of cytokine spectrum in chronic urticarial

Urticaria is a serious medical and social problem due to its high prevalence, lack of unified approaches to diagnosis and treatment, with high financial costs for therapy and rehabilitation. Long-term recurrent course of the disease, resistance to traditional methods of therapy lead to a significant decrease in the quality of life of patients with chronic urticaria. Itching accompanying this disease leads to deterioration in the patient’s general well-being, frequent sleep disturbances and, as a result, significant decrease in working capacity. Up to the present moment, etiopathogenesis of urticaria is a complex challenge due to the multivector nature of cytokine response, interference of protides of the complement system, patterns of kininbradykinin interference, peculiar expression of the immune response. The problem of current population is lipotrophy – chronic, heterogeneous, cytokine mediating, progressive inflammatory disease attributed by abnormal accumulation of excessive adipose tissue. Adipose tissue, being a sporadic organ of endocrine system secretes multiple hormone-like substances, mediators, cytokines and chemokines which have been given a common name, i.e., adipokines or adipocytokines. True signs of destructive parenchymal changes of liver in the form of increasing bilirubin and AST, decreasing level of vitamin D in patients with chronic recurrent urticarial in presence of obesity have been revealed during the study performed. The action of cytokines, as mediators of intercellular interaction is closely related to the physiological and pathophysiological responses of the body with modulation of both local and systemic defense mechanisms. It is assumed that the cytokine status of patients with chronic urticaria is dominated by cytokines that increase allergic inflammation of the skin. Analysis of 12 T regulatory biomarker concentrations revealed increased concentrations of IL-10, IL-19, IL-20, IL-27, IL-35, IFNλ2 and IFNλ1 in blood serum of patients with chronic urticaria. It was found that in the group of patients with chronic urticaria and increased body mass index (BMI), the level of all investigated T regulatory cytokines is lower than in the patients with normal BMI, except for IL-10. Decreased levels of biologically active IFN I (α/β) and, especially, IFN II (γ) types of blood leukocytes in patients with chronic urticaria were revealed. The levels of 12 Treg cytokines were determined in blood serum of patients with chronic urticaria, showing trend for imbalance of Treg cytokines: IL-10, IL-19, IL-20, IL-27, IL-35, IFNλ2 and IFNλ1

Turbulence in the Solar Atmosphere: Manifestations and Diagnostics via Solar Image Processing

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions.Comment: 26 pages, 7 figure

On Solving the Coronal Heating Problem

This article assesses the current state of understanding of coronal heating, outlines the key elements of a comprehensive strategy for solving the problem, and warns of obstacles that must be overcome along the way.Comment: Accepted by Solar Physics; Published by Solar Physic

Large-Eddy Simulations of Magnetohydrodynamic Turbulence in Heliophysics and Astrophysics

We live in an age in which high-performance computing is transforming the way we do science. Previously intractable problems are now becoming accessible by means of increasingly realistic numerical simulations. One of the most enduring and most challenging of these problems is turbulence. Yet, despite these advances, the extreme parameter regimes encountered in space physics and astrophysics (as in atmospheric and oceanic physics) still preclude direct numerical simulation. Numerical models must take a Large Eddy Simulation (LES) approach, explicitly computing only a fraction of the active dynamical scales. The success of such an approach hinges on how well the model can represent the subgrid-scales (SGS) that are not explicitly resolved. In addition to the parameter regime, heliophysical and astrophysical applications must also face an equally daunting challenge: magnetism. The presence of magnetic fields in a turbulent, electrically conducting fluid flow can dramatically alter the coupling between large and small scales, with potentially profound implications for LES/SGS modeling. In this review article, we summarize the state of the art in LES modeling of turbulent magnetohydrodynamic (MHD) ows. After discussing the nature of MHD turbulence and the small-scale processes that give rise to energy dissipation, plasma heating, and magnetic reconnection, we consider how these processes may best be captured within an LES/SGS framework. We then consider several special applications in heliophysics and astrophysics, assessing triumphs, challenges,and future directions