228 research outputs found

    Predicted Abundances of Carbon Compounds in Volcanic Gases on Io

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    We use chemical equilibrium calculations to model the speciation of carbon in volcanic gases on Io. The calculations cover wide temperature (500-2000 K), pressure (10^-8 to 10^+2 bars), and composition ranges (bulk O/S atomic ratios \~0 to 3), which overlap the nominal conditions at Pele (1760 K, 0.01 bar, O/S ~ 1.5). Bulk C/S atomic ratios ranging from 10^-6 to 10^-1 in volcanic gases are used with a nominal value of 10^-3 based upon upper limits from Voyager for carbon in the Loki plume on Io. Carbon monoxide and CO2 are the two major carbon gases under all conditions studied. Carbonyl sulfide and CS2 are orders of magnitude less abundant. Consideration of different loss processes (photolysis, condensation, kinetic reactions in the plume) indicates that photolysis is probably the major loss process for all gases. Both CO and CO2 should be observable in volcanic plumes and in Io's atmosphere at abundances of several hundred parts per million by volume for a bulk C/S ratio of 10^-3.Comment: 21 pages, 4 figures, 4 tables; accepted by Astrophysical Journa

    The Role of CO2 in Aqueous Alteration of Ultra-Mafic Rocks and the Formation of MF-,FE-Rich Aqueous Solutons on Early Mars

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    An adequate understanding of water on Mars that moves beyond the simplistic "warmwet" vs. "cold-dry" dichotomy must include strong constraints on the variables: water/rock ratio, time, temperature, and chemical composition. By constraining these variables first on local, then regional and global scales we will be capable of precisely targeting landed missions to definitively understand the history of water on Mars and the possible existence of life. Data from remote sensing of Mars, landed missions, and martian meteorites indicate that secondary minerals formed from aqueous fluids on Mars are predominately Fe- and Mg-rich. The unique Mg-, Fe-rich carbonates in the ALH 84001 meteorite provide an excellent opportunity to provide strong constraints on an Fe-, Mg-rich aqueous system on early Mars. This work seeks to use the unusual chemical compositions of the ALH 84001 carbonates as a constraint for the composition of their formation fluid. These constraints can be used to better understand aqueous processes at a critical time in martian history

    Atresia of oocytes for northern rock sole <i>Lepidopsetta polyxystra </i>(Pleuronectiformes, Pleuronectidae) from the Pacific waters of Kamchatka

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    Northern rock sole is abundant and important for fishery species in the Pacific waters of Kamchatka and northern Kuril Islands. Sometimes its oogenesis occurs with the oocytes atresia. By the data of the females reproductive tissue investigation conducted in 2011-2012, the degeneration appears for the late perinucleus (II and II-III maturing stages), vitellogene cells (III and IV stages), and ovarian follicles (stages VI-III) and develops by three principally different ways. Comparing with other fish species, atresia of the late perinucleus of northern rock sole realizes without follicular epithelium and affects either 15 % of these cells (for 8 % of juveniles) or 67 % of these cells (for 4 % of non-spawning adults). In the process of the vitellogene oocytes atresia, a symplast forms between follicular epithelium and chorion and conserves until final resorption of the oocyte. The cortical alveoli and vacuolated cells are damaged more often (5.6 %) than the oocytes with advanced yolk (2.4 %). Resorption of ovarian follicles by stroma connective tissue of oviparous plates is typical for all postspawning females, their portion doesn’t exceed 3 % of cells in each generation. Obviously, atresia of vitellogene oocytes reduces the fish fecundity, therefore the total and population fecundity is forming until the stage IV

    Quality Assurance of Medicines: Main Scientific Approaches and Control Methods

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    The most important component of national health policy is the assurance of quality, efficacy, and safety of medicines entering the pharmaceutical market in the Russian Federation. In this interview, we have discussed the quality control of medicines; its interconnections with various branches of science, in particular, with analytical chemistry; and the matters of material and equipment supply with Elena L. Kovaleva (Doctor of Pharmaceutical Sciences, Deputy Director of the Centre for Medicinal Products Evaluation and Control of the Scientific Centre for Expert Evaluation of Medicinal Products of the Ministry of Health of the Russian Federation), Yuri A. Zolotov (Academician of the Russian Academy of Sciences, Full Professor, Doctor of Chemical Sciences), and Dmitry V. Somov (Candidate of Pharmaceutical Sciences, Acting Director General of the Information and Methodological Center for Expertise, Accounting, and Analysis of the Circulation of Medicinal Products of the Federal Service for Surveillance in Healthcare)

    МЕТОДЫ НОРМАЛИЗАЦИИ СТАТИЧЕСКОГО ГЕОМАГНИТНОГО ПОЛЯ В ЖИЛЫХ ДОМАХ

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    In the paper, we show the necessity of normalization of the static geomagnetic field (GMF) inside high-rise frame-monolithic houses to safe values (90% of the natural rate at least). Massive ferromagnetic construction of these buildings significantly (up to 50 %) weakens the natural GMF. The normalization methods are based on mathematical modeling of GMF in a residential area. Simplified physical models of reinforced concrete building structures are developed and used. The results of experimental studies are also used in the framework of the development of the methods. The following methods of normalization of GMF are presented and justified: 1) the use of special steel with a relative permeability less than 70 in housing construction; 2) restrictions on the use of long steel elements with the elongation coefficient in the critical range of 4&lt;b&lt;28; 3) demagnetization of steel reinforcement before installing; 4) preventing the magnetization of steel reinforcement in the construction process. Practical recommendations for the design of «magnetic clean» houses with comfortable living conditions in connection to the GMF are proposed.Показана необходимость нормализации до безопасных значений индукции статического геомагнитного поля (ГМП) в помещениях высотных каркасно-монолитных жилых домов, массивные ферромагнитные несущие конструкции которых значительно (на 50%) ослабляют естественное ГМП. Теоретически и экспериментально обоснованы методы нормализации ГМП, реализуемые без применения дополнительных экранирующих элементов. Разработаны рекомендации по проектированию и строительству «магниточистых» жилых домов с комфортными условиями проживания по статическому геомагнитному полю.Показана необхідність нормалізації до безпечних значень індукції статичного геомагнітного поля (ГМП) у приміщеннях висотних каркасно-монолітних житлових будинків, масивні феромагнітні несучі конструкції яких значно (на 50%) послаблюють природне ГМП. Теоретично і експериментально обґрунтовані методи нормалізації ГМП, що реалізуються без застосування додаткових екрануючих елементів. Розроблено рекомендації з проектування та будівництва «магніточистих» житлових будинків з комфортними умовами проживання за статичним геомагнітним полем

    Long-term dynamics and current state of yellowfin sole <i>Limanda aspera</i> stocks in the waters of Sakhalin Island

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    Commercial stocks of two yellowfin sole populations on the western and eastern shelves of Sakhalin Island are assessed by VPA method using the data on their size-age structure and fishery statistics for 1950-2013. Results of the assessment are compared with the data of bottom trawl surveys conducted in 2000-2013. The yellowfin sole at Sakhalin Island had two periods of high abundance: in the 1950-1960s and in the 1985-1995, but its stocks decreased in the 1970-1980 and after the middle 1990s. This dynamics is similar to the dynamics of other large populations of yellowfin sole in the North Pacific - in the southeastern and western Bering Sea and on the shelf of West Kamchatka. All these changes are caused by natural reasons; fishery has secondary importance and affects on the populations in times of low stock only

    Experimental investigation of single carbon compounds under hydrothermal conditions

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    Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 70 (2006): 446-460, doi:10.1016/j.gca.2005.09.002.The speciation of carbon in subseafloor hydrothermal systems has direct implications for the maintenance of life in present day vent ecosystems and possibly the origin of life on early Earth. Carbon monoxide is of particular interest because it represents a key reactant during the abiotic synthesis of reduced carbon compounds via Fischer-Tropsch-type processes. Laboratory experiments were conducted to constrain reactions that regulate the speciation of aqueous single carbon species under hydrothermal conditions and determine kinetic parameters for the oxidation of CO according to the water water-gas shift reaction (CO2 + H2 = CO + H2O). Aqueous fluids containing added CO2, CO, HCOOH, NaHCO3, NaHCOO, and H2 were heated at 150, 200, and 300°C and 350 bar in flexible cell hydrothermal apparatus, and the abundance of carbon compounds were monitored as a function of time. Variations in fluid chemistry suggest that the reduction of CO2 to CH3OH under aqueous conditions occurs via a stepwise process that involves the formation of HCOOH, CO, and possibly CH2O, as reaction intermediaries. Kinetic barriers that inhibit the reduction of CH3OH to CH4 allow the accumulation of reaction intermediaries in solution at high concentrations regulated by metastable equilibrium. Reaction of CO2 to form CO involves a two-step process in which CO2 initially undergoes a reduction step to HCOOH which subsequently dehydrates to form CO. Both reactions proceed readily in either direction. A preexponential factor of 1.35 x 106 s-1 and an activation energy of 102 KJ mol-1 were retrieved from the experimental results for the oxidation of CO to CO2. Reactions rates amongst single carbon compounds during the experiments suggests SCO2 (CO2 + HCO3- + CO3=), CO, SHCOOH (HCOOH + HCOO-), and CH3OH may reach states of redox-dependent metastable thermodynamic equilibrium in subseafloor and other hydrothermal systems. The abundance of CO under equilibrium conditions, which in turn may influence the likelihood for abiotic synthesis via Fischer-Tropsch-type processes, is strongly dependent on temperature, the total carbon content of the fluid, and host-rock lithology. If crustal residence times following the mixing of high-temperature hydrothermal fluids with cool seawater are sufficiently long, reequilibration of aqueous carbon can result in the generation of additional reduced carbon species such as HCOOH and CH3OH and the consumption of H2. The present study suggests that abiotic reactions involving aqueous carbon compounds in hydrothermal systems are sufficiently rapid to influence metabolic pathways utilized by organisms that inhabit vent environments.This study was supported by the National Science Foundation grant #OCE-0136954, the Office of Basic Energy Sciences, U.S. Department of Energy grant #DEFG0297ER14746, and by NASA Exobiology grant #NAG5-7696 and Origins grant #NNG04GG23G
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