ПОЛУЧЕНИЕ МЕТАЛЛИЧЕСКОЙ СУРЬМЫ С НИЗКИМ СОДЕРЖАНИЕМ МЫШЬЯКА ИЗ АНТИМОНАТНОГО КОНЦЕНТРАТА

The paper provides the method developed by the authors to produce low-arsenic crude antimony from the antimony concentrate containing 47,77 of Sb and 0,17 % of As. The basis of the concentrate is sodium hexahydroxoantimonate or mopungite mineral. Concentrate reduction with coke according to the traditional technology produced crude antimony with a high arsenic content – 0,34 %. To reduce arsenic content in crude metal to 0,1 % and eliminate a separate stage of antimony refining from arsenic, reduction melting is proposed in the presence of sodium plumbite or lead oxide. This allows obtaining crude antimony with an arsenic content of 0,07–0,1 %. The process of antimony concentrate reduction melting on crude antimony was carried out in an oven with silicon carbide heaters in alundum crucibles with charge batches 100–150 g each. The content of base metal and impurities in crude antimony was determined by chemical and atomic absorption methods. The form of arsenic in the concentrate was determined by X-ray phase analysis using the DRON-3 automated diffractometer (CuKα radiation, β filter). Arsenic concentration in the slag phase in the form of Pb2As2O7 lead diarsenate is shown. Thermal gravimetric analysis was performed for reduction melting of charge consisting of antimony concentrate, lead oxide and coke and it was found that metal antimony formation occurs in a temperatures range of 445–950 °C.Представлен разработанный авторами способ получения черновой сурьмы с низким содержанием мышьяка из антимонатного концентрата, содержащего 47,77 % Sb и 0,17 % As. Основу концентрата составляет гексагидроксоантимонат натрия, или минерал мопунгит. При восстановлении концентрата коксом по традиционной технологии получена черновая сурьма с повышенным содержанием мышьяка – 0,34 %. Для его снижения в черновом металле до 0,1 % и исключения отдельной стадии рафинирования сурьмы от мышьяка предложена восстановительная плавка в присутствии плюмбита натрия или оксида свинца, в результате которой получена черновая сурьма с содержанием мышьяка 0,07–0,1 %. Процесс восстановительной плавки антимонатного концентрата на черновую сурьму проводился в печи с силитовыми нагревателями в алундовых тиглях с навесками шихты 100–150 г. Содержание основного металла и примесей в черновой сурьме определялось химическим и атомно-абсорбционным способами. Форма нахождения мышьяка в концентрате оценивалась рентгенофазовым анализом с использованием автоматизированного дифрактометра ДРОН-3 (CuKα-излучение, β-фильтр). Показано концентрирование мышьяка в шлаковой фазе в виде диарсената свинца Pb2As2O7. Проведены термогравиметрические исследования процесса восстановительной плавки шихты, состоящей из антимонатного концентрата, оксида свинца и кокса, в результате которых установлено, что процесс образования металлической сурьмы протекает в интервале температур 445–950 °С

Genetic Deficiency and Pharmacological Stabilization of Mast Cells Ameliorate Pressure Overload-Induced Maladaptive Right Ventricular Remodeling in Mice

Although the response of the right ventricle (RV) to the increased afterload is an important determinant of the patient outcome, very little is known about the underlying mechanisms. Mast cells have been implicated in the pathogenesis of left ventricular maladaptive remodeling and failure. However, the role of mast cells in RV remodeling remains unexplored. We subjected mast cell-deficient WBB6F1-KitW/W-v (KitW/KitW-v) mice and their mast cell-sufficient littermate controls (MC+/+) to pulmonary artery banding (PAB). PAB led to RV dilatation, extensive myocardial fibrosis, and RV dysfunction in MC+/+ mice. In PAB KitW/KitW-v mice, RV remodeling was characterized by minimal RV chamber dilatation and preserved RV function. We further administered to C57Bl/6J mice either placebo or cromolyn treatment starting from day 1 or 7 days after PAB surgery to test whether mast cells stabilizing drugs can prevent or reverse maladaptive RV remodeling. Both preventive and therapeutic cromolyn applications significantly attenuated RV dilatation and improved RV function. Our study establishes a previously undescribed role of mast cells in pressure overload-induced adverse RV remodeling. Mast cells may thus represent an interesting target for the development of a new therapeutic approach directed specifically at the heart

Altered proteasome function in right ventricular hypertrophy.

Aims: In patients with pulmonary hypertension, right ventricular hypertrophy (RVH) is a detrimental condition that ultimately results in right heart failure and death. The ubiquitin proteasome system has been identified as a major protein degradation system to regulate cardiac remodelling in the left heart. Its role in right heart hypertrophy, however, is still ambiguous.Methods and results: RVH was induced in mice by pulmonary artery banding (PAB). Both, expression and activity of the proteasome was found to be up-regulated in the hypertrophied right ventricle (RV) compared to healthy controls. Catalytic inhibition of the proteasome by the two proteasome inhibitors Bortezomib (BTZ) and ONX-0912 partially improved RVH both in preventive and therapeutic applications. Native gel analysis revealed that specifically the 26S proteasome complexes were activated in experimental RVH. Increased assembly of 26S proteasomes was accompanied by elevated expression of Rpn6, a rate-limiting subunit of 26S proteasome assembly, in hypertrophied cardiomyocytes of the right heart. Intriguingly, patients with RVH also showed increased expression of Rpn6 in hypertrophied cardiomyocytes of the RV as identified by immunohistochemical staining.Conclusion: Our data demonstrate that alterations in expression and activity of proteasomal subunits play a critical role in the development of RVH. Moreover, this study provides an improved understanding on the selective activation of the 26S proteasome in RVH that might be driven by the rate-limiting subunit Rpn6. In RVH, Rpn6 therefore represents a more specific target to interfere with proteasome function than the commonly used catalytic proteasome inhibitors

Genetic deletion of p66shc and/or cyclophilin D results in decreased pulmonary vascular tone

Aims The pulmonary vascular tone and hypoxia-induced alterations of the pulmonary vasculature may be regulated by the mitochondrial membrane permeability transition pore (mPTP) that controls mitochondrial calcium load and apoptosis. We thus investigated, if the mitochondrial proteins p66shc and cyclophilin D (CypD) that regulate mPTP opening affect the pulmonary vascular tone. Methods and results Mice deficient for p66shc (p66shc(-/-)), CypD (CypD(-/-)), or both proteins (p66shc/CypD(-/-)) exhibited decreased pulmonary vascular resistance (PVR) compared to wild-type mice determined in isolated lungs and in vivo. In contrast, systemic arterial pressure was only lower in CypD(-/-) mice. As cardiac function and pulmonary vascular remodelling did not differ between genotypes, we determined alterations of vascular contractility in isolated lungs and calcium handling in pulmonary arterial smooth muscle cells (PASMC) as underlying reason for decreased PVR. Potassium chloride (KCl)-induced pulmonary vasoconstriction and KCl-induced cytosolic calcium increase determined by Fura-2 were attenuated in all gene-deficient mice. In contrast, KCl-induced mitochondrial calcium increase determined by the genetically encoded Mito-Car-GECO and calcium retention capacity were increased only in CypD(-/-) and p66shc/CypD(-/-) mitochondria indicating that decreased mPTP opening affected KCl-induced intracellular calcium peaks in these cells. All mouse strains showed a similar pulmonary vascular response to chronic hypoxia, while acute hypoxic pulmonary vasoconstriction was decreased in gene-deficient mice indicating that CypD and p66shc regulate vascular contractility but not remodelling. Conclusions We conclude that p66shc specifically regulates the pulmonary vascular tone, while CypD also affects systemic pressure. However, only CypD acts via regulation of mPTP opening and mitochondrial calcium regulation