ИССЛЕДОВАНИЕ СИСТЕМЫ ВАКУУМНОГО НАСОСА НА ОСНОВЕ ЧИСЛЕННЫХ РАСЧЕТОВ

This article explores the operation of the GB5601 vacuum pump system created by Engineering GmbH based on the 1D model. The system includes a root pump and a liquid ring vacuum pump. The main objective of the study is to develop and verify a numerical model of a vacuum pump system for analysis in various operating modes. Performance assessment was carried out in the software Simcenter AMESim 1D, where the models are assembled in the libraries Signal, Control, Pneumatics and Thermal.В этой статье рассматривается работа системы вакуумных насосов GB5601, созданной Engineering GmbH на основе модели 1D. Система включает корневой насос и жидкостный кольцевой вакуумный насос. Основной целью исследования является разработка и проверка численной модели вакуумной насосной системы для анализа в различных режимах работы. Оценка производительности проводилась в программном обеспечении Simcenter AMESim 1D, где модели собраны в библиотеках Signal, Control, Pneumatics и Thermal

Insurance as a way for reducing the market risks level associated with the collective investments

This article focuses on the need to introduce an insurance mechanism in the implementation of investment funds in the Russian economy. Management companies in order to obtain high profits try to buy securities with high risk level. However in conditions of financial crisis and recession of the share market only highly liquid securities can keep money of shareholder. Moreover, any mutual fund possesses the important feature - if rigidly not to control a structure of its portfolio, it becomes superprofitable, but superrisky. Due the scale of collective investment market any error of management company, which operates with money resources of investors, can lead to serious consequences. There is a kind of insurance like - double insurance. Double insurance occurs when the object is insured against the same risk in the same period of several insurance companies and insurance claims for all contracts, taken together, exceed the cost of insurance. In this article the authors substantiate the need for a mechanism of double insurance. This insurance system, in our opinion, will reduce the level of risk in implementation collective investments, but, despite a slight decrease in the profitability of funds, it will increase investor interest to mutual funds. © IDOSI Publications, 2014

Histamine reduces GPIb?-mediated adhesion of platelets to TNF-?-activatedvascular endothelium

Histamine and tumor necrosis factor-? (TNF-?) are critical mediators of acute and chronic inflammation that are generated by mast cells and macrophages in atherosclerotic lesions or systemically during allergic attacks. Both of them induce activation of vascular endothelium and thus may play a role in thrombosis. Here we studied the interplay between histamine and TNF-? in glycoprotein (GP) Ib?-mediated platelet adhesion to cultured human vascular endothelial cells under static and shear flow conditions. The stimulation of endothelial cells with histamine or TNF-? increased the number of adherent or slow rolling GP Ib?-coated microbeads or washed human platelets. However, the application of histamine to endothelium pre-activated by TNF-? inhibited GP Ib?-mediated platelet adhesion. These effects were found to be associated with changes in the concentration of ultra large von Willebrand factor (ULVWF) strings anchored to endothelium. The results of this study indicate that histamine released during mast cell degranulation may cause or inhibit thrombosis, depending on whether it acts on resting endothelial cells or on cells pre-activated by other inflammatory stimuli

Characterization Of Individual Submicron Perfluorocarbon Gas Bubbles By Ultrasonic Backscatter

Measurements were undertaken to determine the unknown microbubble-size distribution of a dodecafluoropentane (DDFP) emulsion consisting of in surfactant-stabilized water. The acoustic backscatter of 2-microsecond-duration tonebursts of 30-MHz focused ultrasound was measured from the emulsion as it moved in a coaxial flow. Calibration for the system was accomplished using 3-μm-radius polystyrene spheres, using a linear scattering model and literature values for polystyrene. Applying viscous linear scattering theory to the backscatter data from individual DDFP bubbles allowed inversion of the radius–backscatter relation. A mean microbubble radius of 130 nm was inferred for the DDFP population. © 2005 Acoustical Society of America

PDMS Well Platform for Culturing Millimeter-Size Tumor Spheroids

Multicellular tumor spheroids are widely used as in vitro models for testing of anticancer drugs. The advantage of this approach is that it can predict the outcome of a drug treatment on human cancer cells in their natural three-dimensional environment without putting actual patients at risk. Several methods were utilized in the past to grow submillimeter-size tumor spheroids. However, these small models are not very useful for preclinical studies of tumor ablation where the goal is the complete destruction of tumors that can reach several centimeters in diameter in the human body. Here, we propose a PDMS well method for large tumor spheroid culture. Our experiments with HepG2 hepatic cancer cells show that three-dimensional aggregates of tumor cells with a volume as large as 44 mm3 can be grown in cylindrical PDMS wells after the initial culture of tumor cells by the hanging drop method. This is a 350 times more than the maximum volume of tumor spheroids formed inside hanging drops (0.125 mm3 )

Gerhard Richter's Creativity as a Transformation of Historical Genre in European Art of the Xx Century

The second half of the twentieth century is marked by a high rhythm of change, which is very clearly manifested in art as a reflection of real time. In the 1960s, a new genre - a photo-painting - got its life. This genre has actively declared itself in the work of Gerhard Richter. Synthesizing paintings and photographs symbolizes the beginning of the artist's creative path. Richter's work is multidimensional and specific. This led to an increase in interest in him from the art historians and cultural experts of our time. The purpose of this article is an art history and cultural analysis of Gerhard Richter's paintings as a reflection of the transformation of twentieth-century art.The article uses the methods of discursive analysis, immersion method

The effect of elasto-plastic properties of materials on their formability by flow forming

FEA process modelling, which has seen plenty of development in recent decades, has significantly simplified and broadened our capabilities for designing and optimising metal forming processes. It has become relatively easy to find the stress-strain state at any point and instant in the process, analyse the kinematics of metal flow or test different fracture criteria. However, it is frequently the case that all this information cannot compensate for the lack of a fundamental understanding of the process. Flow forming is a case in point. Although much research has been carried out since the 1960’s and has resulted in considerable industrial experience, still many aspects remain as “know how” and many basic questions do not have exact answers. This work reported herein is focused on the role of the elasto-plastic properties of a material with respect to its use in flow forming. Can the flow formability of a material be assessed using data from a uniaxial tensile test? If there exists the possibility of tailoring mechanical properties by heat treatment, what should be prioritised

Productivity of corn Ross 140 depending on the level of the chemicalization of zonal soils of the republic of Tatarstan

It is known that one and the same corn plant material can be used to produce silage, cornage, milled grain, or grain for fodder. Each of them contains completely different amounts of nutrients and a wide range of gross yield of fodder units. The results of the research show the direct dependence of the choice of corn use on zonal features of the soil cover and the existing level of chemicalization of agricultural formations of the Republic of Tatarstan, which are considered in detail in this paper. Thus, in order to produce the ploughed grain or corn with the gross harvest of fodder units 7.94–8.82 t/ha and profitability of 78.7% on leached chernozems, which account for 38% of soils of the Republic of Tatarstan, it is recommended to cultivate corn using the complex application of agromeliorants and calculated norms of mineral fertilizers. Liming of acidic dark gray and gray forest soils with phosphorite and zeolite application in combination with NPK provides increase in gross harvest of fodder units of corn silage from 4.22 to 6.13 and 3.34 to 5.86 t/ha respectively. The high efficiency of agrochemicals application on corn crops and forage harvesting of different types of fodder taking into account zonal features of soil cover of the Republic of Tatarstan is also confirmed by economic indicators. The profitability of production of rolled grain reaches the maximum value (78.8%) in the variant with liming and phosphating of leached chernozem combined with the application of mineral fertilizers in rates calculated for obtaining the planned 35 t/ha of green mass. At the same time, on dark gray and gray forest soils as the yield of green mass increases under the influence of agromeliorants the total costs of silage production increases by 13.1 and 16.5 thousand rubles/ha compared with the control variants of the experiment (without agrochemicals). However, the costs of production of 1 000 fodder units are reduced to 9.9 and 10.4 thousand rubles respectively, provided that the sale price is about14 thousand rubles

A case of arterial thrombosis with formation of an atypical fibrin-rich thrombus

Aim. To describe a case of arterial thrombosis with a thrombus that had atypical composition due to profound pathological changes in the cellular and protein composition of the blood. Methods. Scanning electron microscopy of an ex vivo thrombus extracted from the common femoral artery. Results. In the absence of platelets and leukocytes there was a significant prevalence of fibrin over other blood components in all layers of the arterial thrombus. There were no morphological signs of intravital contraction (retraction) characteristic for thrombi: single erythrocytes were not exposed compressive deformation, redistribution of fibrin and platelets within the thrombus toward the periphery. Formation of the atypical arterial thrombus in the vessel with atherosclerotic vessel damage is probably due to association with severe hyperfibrinogenemia and thrombocytopenia. Conclusion. The structure of a thrombus depends not only on its vascular location (arterial or venous), but also on the cellular and protein composition of the blood. These factors support diversification of antithrombotic therapy, considering composition and properties of thrombi irrespective of the place and hemodynamic conditions of their formation