Статті в журналах: "Equilibrium composition of the environment"

1

GLADYSHEV, G. P., D. KH KITAEVA, and E. N. OVCHARENKO. "WHY DOES THE CHEMICAL COMPOSITION OF LIVING THINGS ADAPT TO THE ENVIRONMENT?" Journal of Biological Systems 04, no. 04 (December 1996): 555–64. http://dx.doi.org/10.1142/s0218339096000351.

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It is shown, using the example of fatty acids contained in living things, that the temperature adaptation of the living things chemical composition is a consequence of the second principle of thermodynamics in its classical form. The obtained result is interesting since the application of equilibrium thermodynamics to living organisms was being rejected for a long time because of the complexity and open nature of these organisms.

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2

Ibañez-Mejia, Mauricio, and François L. H. Tissot. "Extreme Zr stable isotope fractionation during magmatic fractional crystallization." Science Advances 5, no. 12 (December 2019): eaax8648. http://dx.doi.org/10.1126/sciadv.aax8648.

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Zirconium is a commonly used elemental tracer of silicate differentiation, yet its stable isotope systematics remain poorly known. Accessory phases rich in Zr4+ such as zircon and baddeleyite may preserve a unique record of Zr isotope behavior in magmatic environments, acting both as potential drivers of isotopic fractionation and recorders of melt compositional evolution. To test this potential, we measured the stable Zr isotope composition of 70 single zircon and baddeleyite crystals from a well-characterized gabbroic igneous cumulate. We show that (i) closed-system magmatic crystallization can fractionate Zr stable isotopes at the >0.5% level, and (ii) zircon and baddeleyite are isotopically heavy relative to the melt from which they crystallize, thus driving chemically differentiated liquids toward isotopically light compositions. Because these effects are contrary to first-order expectations based on mineral-melt bonding environment differences, Zr stable isotope fractionation during zircon crystallization may not solely be a result of closed-system thermodynamic equilibrium.

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3

Novikov, Dmitry A. "Chemical equilibrium of groundwater with minerals of the host rocks in Upper Jurassic sediments (Arctic regions of Western Siberia)." E3S Web of Conferences 98 (2019): 01037. http://dx.doi.org/10.1051/e3sconf/20199801037.

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The results of thermodynamic calculations for a water-rock system in the Upper Jurassic deposits of the Arctic regions of Western Siberia are presented. In the area under investigation the groundwaters have been identified with mineralization up to 63.3 g/L and various chemical composition and genesis. Despite the long interaction with the rock (150-160 ma) equilibrium with endogenous minerals (albite, microcline and anorthite) is practically not observed. At the same time, groundwaters are in equilibrium with clay minerals and micas, such as: Caand Na-montmorillonites, kaolinite, paragonite, margarite, illite, muscovite and Mg-chlorite. The establishment of a balance of groundwater with primary aluminosilicate minerals is also affected by interactions with carbonate minerals. The differences in composition of groundwater in equilibrium with certain aluminosilicates and carbonates indicate that the mineral changes are formed from a solution of a strictly defined chemical composition in an appropriate geochemical environment.

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4

Yamamoto, Tetsuo. "Chemical Composition of Dust Expected from Condensation Models." International Astronomical Union Colloquium 126 (1991): 413–20. http://dx.doi.org/10.1017/s025292110006721x.

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AbstractThis review examines to what degrees the present chemical equilibrium condensation models are effective in predicting chemical composition of grains observed in a variety of cosmic environments. The composition expected from the equilibrium calculations is reviewed separately for refractory (rocky and metallic) and volatile (icy) components. Comments are given on the limitation of the equilibrium calculations in predicting the grain composition. By taking cometary ice as a typical cosmic volatile condensate, it is pointed out that its composition is far from that expected from the equilibrium models. Theories on the formation of cometary volatiles are reviewed, and an observational clue helpful to testing the theories is pointed out. Discussion is given on the advantage for formation of organic materials from volatile solids.

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5

Novikov, D. A. "CATAGENETIC ALTERATION HYDROGEOCHEMISTRY OF SEDIMENTARY ROCKS OF HYDROCARBON OCCURRENCES IN ARCTIC AREASOF THE WESTERN SIBERIAN MEGABASIN." Oil and Gas Studies, no. 6 (December 1, 2016): 19–25. http://dx.doi.org/10.31660/0445-0108-2016-6-19-25.

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For the first time a detailed analysis of the equilibrium-non-equilibrium state of ground waters of hydrocarbon occurrences in Arctic areas of the West Siberian megabasin based on physico-chemical modeling of equilibria in the «water-rock» revealed hydrogeochemical and thermodynamic conditions for the formation of authigenic minerals. For the first time equilibrated compositions of groundwaters and parameters of geochemical environment were identified, being a prerequisite for the mineral neoformations.

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6

Dřímal, Pavel, Josef Hrnčiřík, and Jaromír Hoffmann. "Assessing Aerobic Biodegradability of Plastics in Aqueous Environment by GC-Analyzing Composition of Equilibrium Gaseous Phase." Journal of Polymers and the Environment 14, no. 3 (August 25, 2006): 309–16. http://dx.doi.org/10.1007/s10924-006-0024-5.

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7

Cusack, Maggie, David Parkinson, Alberto Pérez-Huerta, Jennifer England, Gordon B. Curry та Anthony E. Fallick. "Relationship between δ18O and minor element composition of Terebratalia transversa". Earth and Environmental Science Transactions of the Royal Society of Edinburgh 98, № 3-4 (вересень 2007): 443–49. http://dx.doi.org/10.1017/s1755691008075671.

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ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

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8

Filatov, E. S. "Investigations of the corrosion activity of the KAlCl4 melts by the methods of physicochemical analysis." Practice of Anticorrosive Protection 24, no. 4 (December 1, 2019): 59–66. http://dx.doi.org/10.31615/j.corros.prot.2019.94.4-7.

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Corrosion behavior of metal alloys in a melt of potassium chloroaluminate (KAlCl4) was investigated. Metal aluminum was used as a protector for protection against continuous frontal corrosion. The equilibrium potentials of aluminum and the corrosion potential of the alloys were measured. The data were obtained to evaluate the corrosion ability of the system of molten salt of potassium chloroaluminate - gas (argon) by measuring the redox potential of the specified environment depending on the composition of the gas atmosphere above it, i.e. from impurities of water vapor, hydrochloric acid, oxygen and other, for example, carbonaceous gases. The calculations of the protection efficiency using the potential difference between the metal aluminum and the protected material were performed. The regularities of changes in the equilibrium potentials of aluminum from the temperature and concentration were established as the fundamental data for possible use at determining the composition ratio of potassium chlorides and aluminum in potassium chloroaluminate as input data for the development of a sensor of composition of chloroaluminate potassium.

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9

Boivin, Edouard, Jean-Noël Chotard, Michel Ménétrier, Lydie Bourgeois, Tahya Bamine, Dany Carlier, François Fauth, Emmanuelle Suard, Christian Masquelier, and Laurence Croguennec. "Structural and electrochemical studies of a new Tavorite composition: LiVPO4OH." Journal of Materials Chemistry A 4, no. 28 (2016): 11030–45. http://dx.doi.org/10.1039/c6ta03339c.

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A vanadium based hydroxy-phosphate of the Tavorite-type structure LiVPO₄OH was obtained for the first time, by a hydrothermal route. Li⁺ and H⁺ are extracted from the structure at the same equilibrium potential.

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10

Fedorenkova, L. "Formation of Hydrides in the Surface Layer of Aluminum in NonEquilibrium Conditions of Electrolyte Plasma." Фізика і хімія твердого тіла 20, no. 2 (July 10, 2019): 181–84. http://dx.doi.org/10.15330/pcss.20.2.181-184.

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In this paper, the formation of a diffusion layer on aluminum, which includes aluminum hydrides, in non-equilibrium conditions of electrolyte plasma with high local temperatures, high heating and cooling rates were studied. As a result of the research it was obtained that in the diffusion layer formed complex nanosized inclusions of polymorphic modifications (AlН3)n and AlB3H12. The diffusion in the non-equilibrium conditions of the electrolyte plasma is carried out in hydrogen environment, where the hydrogen atoms have the greatest energy and is one of the main forces that activate the diffusion process and influence the structure, composition and micromechanical characteristics of the diffusion layer.

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11

Saxena, S. C., and L. A. Thomas. "An equilibrium model for predicting flue-gas composition of an incinerator." International Journal of Energy Research 19, no. 4 (June 1995): 317–27. http://dx.doi.org/10.1002/er.4440190405.

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12

Arbiter, Beno, Niko Samec, Aleksandar Jovovic, and Filip Kokalj. "Assessment of a simplified equilibrium model for waste gasification." Thermal Science 23, Suppl. 5 (2019): 1473–86. http://dx.doi.org/10.2298/tsci180726316a.

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The applicability is studied of a simplified equilibrium model for prediction of the composition and quality of producer gas from gasification of different waste. A simplified equilibrium model of stoichiometric type based on system thermodynamic equilibrium has been developed in the form of a stand-alone computer application. Standard numerical methods have been implemented for solving the mathematical problem formulation. The model`s predicted results have been compared with the published results for biomass and some waste types - municipal solid wastes and refuse derived fuels. Results are included for a bubbling fluidized bed and downdraft fixed bed allothermal gasification, also for catalytic supported gasification. Producer gas predictions by calibrated and non-calibrated versions of the simplified equilibrium model have been studied. The accuracy of these predictions has been evaluated. The results obtained by the simplified equilibrium model have confirmed that such model is a very useful tool for studying the gasification process for municipal solid wastes and refuse derived fuels process parameters for two mostly implemented gasifier types.

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13

Vujovic, Velibor. "Determining the composition of high temperature combustion products of fossil fuel based on variational principles and geometric programming." Thermal Science 15, no. 1 (2011): 125–34. http://dx.doi.org/10.2298/tsci100928007v.

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This paper presents the algorithm and results of a computer program for calculation of complex equilibrium composition for the high temperature fossil fuel combustion products. The method of determining the composition of high temperatures combustion products at the temperatures appearing in the open cycle MHD power generation is given. The determination of combustion product composition is based on minimization of the Gibbs free energy. The number of equations to be solved is reduced by using variational principles and a method of geometric programming and is equal to the sum of the numbers of elements and phases. A short description of the computer program for the calculation of the composition and an example of the results are also given.

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14

Zippa, Elena, Ivan Bragin, George Chelnokov, and Natalia Kharitonova. "The Annenskiy thermal waters as the certain stage of the water-rock interaction (Far East, Russia)." E3S Web of Conferences 98 (2019): 01054. http://dx.doi.org/10.1051/e3sconf/20199801054.

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Chemical composition and saturation degree of the Annenskiy thermal waters to minerals of water-bearing rock have been considered in the manuscript. It is shown that the thermal waters are low mineralized, alkaline and belong to HCO3-Na type. The thermal waters-rock system is equilibrium-nonequilibrium. It means that the waters dissolve primary minerals continuously, never reaching saturation (anorthite, K-field spar and etc.), and form new secondary mineral phases simultaneously, reaching saturation (gibbsite, montmorillonite, albite and etc.). Besides, peculiarities of the equilibrium with minerals of water-bearing rocks for surface and ground waters of the studied region was considered. It is established that the thermal waters are ahead of surface and ground waters and represent the certain stage of the water-rock system evolution. The stage is characterized by the certain chemical composition (TDS=148-317 mg/L, HCO3-Na, SiO2=9-80 mg/L), complex of secondary minerals (calcite, albite, laumontite and etc.) and special geochemical environment (pH 8.2-8.6).

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15

Panin, P. V., I. A. Bogachev, and E. A. Lukina. "Production and investigation of powders for additive synthesis from a new beta-solidifying TiAl-based alloy." Journal of Physics: Conference Series 2144, no. 1 (December 1, 2021): 012004. http://dx.doi.org/10.1088/1742-6596/2144/1/012004.

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Abstract Chemical composition, structure, and technological properties have been investigated for metal powder compositions (MPCs) of a new six-component TiAl-based alloy with Gd microadditions: Ti-31.0Al-2.5V-2.5Nb-2.5Cr-0.4Gd, wt.% (Ti-44.5Al-2V-1Nb-2Cr-0.1Gd, at.%). Three MPCs fractions (10–63, 40–100, 80–120 μm) were produced by electrode induction melting and inert gas atomization technique and targeted for the additive synthesis of parts. It is shown that the chemical composition of the MPCs for the main elements corresponds to that of the electrode. In contrast, a 1.5-fold increase of the oxygen content in the MPCs was observed, which is being the result of natural oxidation of powder particles upon air environment due to developed specific surface. It has been determined that the phase composition of the MPCs (γ+α(α2)+β) differs from the equilibrium phase composition of the electrode (γ+α2)+β0/B2) and corresponds to a rapidly quenched metastable state, which indicates high solidification rates in the atomization process, exceeding critical cooling rates of the alloy. The technological properties, specifically the powder flowability, were found to be improved for 40–100 and 80–120 μm fractions, making them applicable for additive synthesis of parts from the studied alloy by selective electron-beam melting method

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16

Mayayo, M. J., B. Bauluz, and J. M. Gonzalez Lopez. "Variations in the chemistry of smectites from the Calatayud Basin (NE Spain)." Clay Minerals 35, no. 2 (April 2000): 365–74. http://dx.doi.org/10.1180/000985500546837.

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AbstractSmectites of sedimentary series from a playa lake system from Calatayud Basin have been studied by XRD and TEM chemical microanalyses. Clay particle microanalyses show complete continuity between dioctahedral aluminous and trioctahedral magnesian smectites. Aluminous smectites have been classified as montmorillonites and ferribeidellites, both with compositional variability. They represent detrital phases resulting from weathering in the source area. Compositionally-intermediate smectites (beidellite-saponite and montmorillonite-stevensite) seem to correspond to weighted mean compositions of di- and trioctahedral phases stacked together in the same particle. They represent intermediate transitional stages from detrital to authigenic smectites in more distal basin facies. Trioctahedral smectites, although called saponites and stevensites, are actually random mixed-layer kerolite-Mg-smectite with a high percentage of expandable layers. They represent authigenic clays formed from solutions with high pH and Mg content as a result of evaporative concentration. The variability in composition of smectites, both within the same sample and amongst different samples, is a possible consequence of the heterogeneity in the local chemical environment, and so, equilibrium may be only reached locally in a large variety of microsystems.

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17

Silva, V. B., and A. Rouboa. "Predicting the syngas hydrogen composition by using a dual stage equilibrium model." International Journal of Hydrogen Energy 39, no. 1 (January 2014): 331–38. http://dx.doi.org/10.1016/j.ijhydene.2013.10.053.

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18

ALASHAB, S., and I. HARRIS. "Hydrogen solubility and the equilibrium pressure-composition isotherm for PdEu alloys." International Journal of Hydrogen Energy 13, no. 3 (1988): 191–94. http://dx.doi.org/10.1016/0360-3199(88)90018-3.

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19

Redermeier, Alice, and Ernst Kozeschnik. "Bridging the Gap between Ab Initio and Large Scale Studies - A Monte Carlo Study of Cu Precipitation in Fe." Materials Science Forum 879 (November 2016): 1564–69. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1564.

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In the present study, we investigate the performance of efficient pair potentials in comparison to accurate ab initio potentials as energy descriptions for Monte Carlo simulations of solid-state precipitation. As test scenario, we take the phase decomposition kinetics in binary Fe1-xCux. In a first effort, we predict thermodynamic equilibrium properties of bcc-rich Cu precipitates in an Fe-rich solution with a temperature and composition dependent Cluster Expansion. For this Cluster Expansion, combined ab inito and phonon calculations for various configurations serve as input. Alternatively, we apply the Local Chemical Environment approach, where the energy is described by computationally efficient pair potentials, which are calibrated on the first principles cluster expansion results. We observe that these fundamentally different approaches provide similar information in terms of the precipitate radius, chemical composition and interface constitution, however, the computational effort for the Local Chemical environment approach is significantly lower.

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20

Gupta, A. K., E. Ilanchezhian, and E. L. Keating. "Thermal Destruction Behavior of Plastic and Nonplastic Wastes in a Laboratory-Scale Facility." Journal of Energy Resources Technology 118, no. 4 (December 1, 1996): 269–76. http://dx.doi.org/10.1115/1.2793873.

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Experimental and theoretical studies are presented from a laboratory-scale thermal destruction facility on the destruction behavior of surrogate plastic and nonplastic solid wastes. The nonplastic waste was cellulosic, while the plastic waste contained compounds, such as polyethylene, polyvinyl chloride, polystyrene, polypropylene, nylon, rubber, and polyurethane, or any of their desired mixtures. A series of combustion tests was performed with samples containing varying composition test was performed with samples containing varying composition of plastic and nonplastic. Experimental results are presented on combustion parameters (CO, excess air, residence time) and toxic emissions (dioxin, furan, metals). Equilibrium thermochemical calculations are presented on the thermal destruction behavior of samples under conditions of pyrolysis, combustion, and pyrolysis followed by combustion. Special interest is on the effect of waste properties and input operational parameters on chemistry and product composition. STANJAN and SOLGASMIX computer codes were used in the chemical equilibrium study. Analysis and interpretation of the data reveal the effect of waste feed composition on combustion parameters and dioxin, furan, and metals emission. Equilibrium calculation results are used to describe the experimentally observed trends for the thermal destruction behavior of these wastes. The results show significant influence of plastic on combustion characteristics, and dioxin, furan, and metals emission.

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21

Moretti, Linda, Fausto Arpino, Gino Cortellessa, Simona Di Fraia, Maria Di Palma, and Laura Vanoli. "Reliability of Equilibrium Gasification Models for Selected Biomass Types and Compositions: An Overview." Energies 15, no. 1 (December 22, 2021): 61. http://dx.doi.org/10.3390/en15010061.

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In this paper, the authors present an overview of biomass gasification modeling approaches with the aim of evaluating their effectiveness as a modeling tool for the design and optimization of polygeneration plants based on biomass gasification. In fact, the necessity to build plant operating maps for efficiency optimization requires a significant number of simulations, and non-stoichiometry equilibrium models may allow fast computations thanks to their relative simplicity. The main objective consists of the assessment of thermodynamic equilibrium models performance as a function of biomass type and composition to better understand in which conditions of practical interest such models can be applied with acceptable reliability. To this aim, the authors developed two equilibrium models using both a commercial software (referred as Aspen model) and a simulation tool implemented in a non-commercial script (referred as analytical model). To assess their advantages and disadvantages, the two models were applied to the gasification simulation of different biomasses, employing experimental data available from the scientific literature. The obtained results highlighted strengths and limitations of using equilibrium models as a function of biomass type and composition. For example, they showed that the analytical model predicted syngas composition with better accuracy for biomass types characterized by a low ash content, whereas the Aspen model appeared to fairly predict the syngas composition at different conditions of ER; however, its accuracy might be reduced if the properties of the treated biomass changed.

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22

Povar, I., Nina Timbaliuc, Tatiana Cazac, Diana Shepel, Oxana Spinu, and Ludmila Chiriac. "To the Equilibrium Model Choice in Heterogeneous Aqueous Systems. 1. Theoretical Basis in the Case of Two Coexisting Solid Phases." Chemistry Journal of Moldova 6, no. 1 (June 2011): 57–61. http://dx.doi.org/10.19261/cjm.2011.06(1).11.

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An approach has been developed to determine the equilibrium model in heterogeneous aqueous systems containing a mixture of solid phases from the initial composition of the heterogeneous mixture and the equilibrium values of the pH. This approach allows to significantly reduce the quantity of measured data, properly for solubility measurements. By using the new deduced equations it is possible to determine the solubility products of precipitates on the basis of the known composition of initial mixtures and pH values of saturated solutions avoiding some difficult experimental solubility measurements. The derived relations are useful for solving both direct and indirect equilibrium problems.

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23

YU, YUNDAN, HONGLIANG GE, GUOYING WEI, LI JIANG, and DONG ZHANG. "2024 ALUMINUM OXIDE FILMS PREPARED BY THE INNOVATIVE AND ENVIRONMENT-FRIENDLY OXIDATION TECHNOLOGY." Surface Review and Letters 27, no. 12 (August 26, 2020): 2050020. http://dx.doi.org/10.1142/s0218625x20500201.

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A kind of environment-friendly anodic oxidation technology was used to oxidize 2024 aluminum alloys from mixed acid solutions to effectively improve the anticorrosion and mechanical performances. The influences of anode oxidation method on surface morphology, microstructure, composition, electrochemistry parameter, anticorrosion property were studied. Aluminum alloy oxidation is actually a dynamic equilibrium process of the formation and dissolution of oxide film which is composed of porous and non-porous layer. With the treatment of anodic oxidation, [Formula: see text]-Al2O3 and [Formula: see text]-Al2O3 structures were obtained on the surface of aluminum alloys, which contributed directly to the increase of anticorrosion performance. The potassium dichromate solution was used to seal the surface of oxide films to further improve the anticorrosion property. The oxide films sealed with potassium dichromate were covered with leaf-like structures resulting in larger corrosion resistance that attributed directly to the decrease of corrosion current.

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Fuchs, J., J. C. Schmid, S. Müller, A. M. Mauerhofer, F. Benedikt, and H. Hofbauer. "The impact of gasification temperature on the process characteristics of sorption enhanced reforming of biomass." Biomass Conversion and Biorefinery 10, no. 4 (May 31, 2019): 925–36. http://dx.doi.org/10.1007/s13399-019-00439-9.

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AbstractEspecially carbon-intensive industries are interested in a decarbonization of their processes. A technology, which can contribute to a significant reduction of the carbon footprint, is the so-called sorption enhanced reforming process. The sorption enhanced reforming process uses a dual fluidized bed reactor system with limestone as a bed material for the thermochemical conversion of biomass into a valuable nitrogen-free product gas. This product gas can be used for further synthesis processes like methanation. The dependency of the product gas composition on the gasification temperature is already a well-known fact. Nevertheless, detailed investigations and models of the effect on elemental balances (especially carbon) of the process are missing in the literature and are presented in this work. Therefore, previously published data from different pilot plants is summarized and is discussed on a mass balance. Based on this information, investigations on the product gas equilibrium composition are presented and conclusions are drawn: it can be shown that the sorption enhanced reforming process can be divided into two sub-processes, namely “carbonation dominated sorption enhanced reforming” and “water-gas shift dominated sorption enhanced reforming.” The sub-process carbonation dominated SER is characterized by a high deviation from the water-gas shift equilibrium and a nearly constant CO content in the product gas over gasification temperature (< 700 °C). The sub-process water-gas shift dominated SER can be identified by a steep increase of the CO content in the product gas over temperature and nearly equilibrium state of the water-gas shift reaction (700–760 °C).

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25

Erickson, W. D., and R. K. Prabhu. "Rapid computation of chemical equilibrium composition: An application to hydrocarbon combustion." AIChE Journal 32, no. 7 (July 1986): 1079–87. http://dx.doi.org/10.1002/aic.690320704.

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26

Bolot, M., B. Legras, and E. J. Moyer. "Modelling and intepreting the isotopic composition of water vapour in convective updrafts." Atmospheric Chemistry and Physics Discussions 12, no. 8 (August 31, 2012): 22451–533. http://dx.doi.org/10.5194/acpd-12-22451-2012.

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Abstract. The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener-Bergeron-Findeisen process). As all of these processes are related to updraft strength, droplet size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

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27

Bolot, M., B. Legras, and E. J. Moyer. "Modelling and interpreting the isotopic composition of water vapour in convective updrafts." Atmospheric Chemistry and Physics 13, no. 16 (August 16, 2013): 7903–35. http://dx.doi.org/10.5194/acp-13-7903-2013.

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Abstract. The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process). As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

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Raza, Syed Shabbar, Sherien Elagroudy, and Isam Janajreh. "Gasification of Municipal Solid Waste: Thermodynamic Equilibrium Analysis Using Gibbs Energy Minimization Method and CFD Simulation of a Downdraft Gasifier." Journal of Solid Waste Technology and Management 46, no. 3 (August 1, 2020): 274–88. http://dx.doi.org/10.5276/jswtm/2020.274.

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Millions of tons of municipal solid waste (MSW) are generated annually, posing dramatic threats to our environment. To reduce its environmental impact, MSW can be segregated and thermochemically converted into clean syngas (CO and H2) fuel via gasification process. The feasibility of Gasification of MSW depends on its composition and quantity. In this work, assessment of the gasification metric of MSW is conducted under steam (H2O) as gasification moderator in a pilot scale 20kW gasifier. The characteristic of local MSW are experimentally determined using Flash 2000 organic analyzer (CHNS-O), the thermo-gravimetric analyzer (TGA) and bomb calorimeter following ASTM standards and arriving to molar formula of MSW. A thermodynamic equilibrium model based on Gibbs energy minimization method is used for the steam gasification of MSW to assess the composition of syngas. Using the baseline operating condition from the thermodynamic equilibrium model, a reactive high fidelity numerical model of a downdraft gasifier is developed to gain more fidelity. Result of gasification efficiency of thermodynamic model is 64% while reactive model gives 7% additional efficiency. Nonetheless, the stipulated efficiency and the high-quality syngas produced via the steam gasification of MSW suggest the viability of the process scale up.

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29

Kubota, T., T. Ohta, Y. Mahara, and A. Kudo. "Comparison of deep underground neutron flux measured with a helium-3 filled proportional counter and evaluated from element composition or isotopic ratio of 36Cl/Cl in granite rock." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 227–32. http://dx.doi.org/10.1524/rcpr.2011.0040.

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Abstract The chlorine isotopic ratio and elemental composition of two granite cores collected in a deep underground tunnel has been measured; neutrons were detected using a helium-3-filled proportional counter placed in a borehole. The thermal neutron flux determined from the chlorine isotopic ratio from accelerator mass spectrometry is (3.8 ± 0.2) × 10−5 and that determined from the granite's elemental composition is (4.4 ± 0.3) × 10−5(cm−2 s−1). The results of in-situ measurements using the proportional counter yielded a thermal neutron flux value of (3.3 ± 0.1) × 10−5(cm−2 s−1). This good agreement among the results shows the validity of the neutron flux evaluation obtained from the elemental composition and/or the isotopic ratio of 36Cl/Cl. Further, it reveals that the neutron flux in the underground environment remains stable for at least one million years, i.e., the period over which chlorine-36 attains equilibrium.

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30

Ozilgen, S. "Influence of chemical composition and environmental conditions on the textural properties of dried fruit bars." Czech Journal of Food Sciences 29, No. 5 (October 7, 2011): 539–47. http://dx.doi.org/10.17221/303/2009-cjfs.

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The influences of the composition, environmental humidity, and temperature on the stability of dried fruit bars during storage were investigated. Sultana bars were chosen to represent similar types of fruit bars. The moisture sorption isotherms and textural stability of sultana bars with and without glucose and maltodextrin additives were determined at 20°C and 40°C using the standard static gravimetric method. The shape of all of the isotherms was found to be typical of high sugar foods and could be explained by four different models. Additives and storage temperatures affected the monolayer moisture content, equilibrium moisture content, and the textural stability of the sultana bars during storage at the same water activity. The relationship between the loss of stiffness and water activity had a sigmoid shape and was explained by Fermi’s equation. This paper fills an important gap with that which does not exist in a large number of sorption behaviour publications available in the literature. It presents real data explaining the true mechanism of textural change during storage with both water activity and glass transition theories for high sugar fruit pastes. The information obtained from this study may help the food producers, who make high sugar containing dried fruit products, to create better textural and sensory properties, and may also help to predict the storage stability and packaging requirements.

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31

Lapenna, Annamaria, Fiorenza Fanelli, Francesco Fracassi, Vincenza Armenise, Valeria Angarano, Gerardo Palazzo, and Antonia Mallardi. "Direct Exposure of Dry Enzymes to Atmospheric Pressure Non-Equilibrium Plasmas: The Case of Tyrosinase." Materials 13, no. 9 (May 9, 2020): 2181. http://dx.doi.org/10.3390/ma13092181.

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The direct interaction of atmospheric pressure non-equilibrium plasmas with tyrosinase (Tyr) was investigated under typical conditions used in surface processing. Specifically, Tyr dry deposits were exposed to dielectric barrier discharges (DBDs) fed with helium, helium/oxygen, and helium/ethylene mixtures, and effects on enzyme functionality were evaluated. First of all, results show that DBDs have a measurable impact on Tyr only when experiments were carried out using very low enzyme amounts. An appreciable decrease in Tyr activity was observed upon exposure to oxygen-containing DBD. Nevertheless, the combined use of X-ray photoelectron spectroscopy and white-light vertical scanning interferometry revealed that, in this reactive environment, Tyr deposits displayed remarkable etching resistance, reasonably conferred by plasma-induced changes in their surface chemical composition as well as by their coffee-ring structure. Ethylene-containing DBDs were used to coat tyrosinase with a hydrocarbon polymer film, in order to obtain its immobilization. In particular, it was found that Tyr activity can be fully retained by properly adjusting thin film deposition conditions. All these findings enlighten a high stability of dry enzymes in various plasma environments and open new opportunities for the use of atmospheric pressure non-equilibrium plasmas in enzyme immobilization strategies.

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32

Tranter, Martyn, Giles Brown, Robert Raiswell, Martin Sharp, and Angela Gurnell. "A conceptual model of solute acquisition by Alpine glacial meltwaters." Journal of Glaciology 39, no. 133 (1993): 573–81. http://dx.doi.org/10.1017/s0022143000016464.

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Abstract Solute acquisition by Alpine glacial meltwaters is the result of the coupling of different pairs of reactions, one of which usually involves dissolved gases. Hence, the availability of atmospheric gases to solution is an important control on the composition of glacial meltwaters. The chemical compositions of the two main components of the bulk meltwater, quick flow and delayed flow, are dominated by different geochemical processes. Delayed flow waters are solute-rich and exhibit high p(CO2) characteristics. The slow transit of these waters through a distributed drainage system and the predominance of relatively rapid reactions, such as sulphide oxidation and carbonate dissolution, in this environment maximize solute acquisition. Quick-flow waters are dilute, both because of their rapid transit through ice-walled conduits and open channels, and because the weathering reactions are fuelled by relatively slow gaseous diffusion of (CO2) into solution, despite solute acquisition being dominated by rapid surface exchange reactions. As a consequence, quick flow usually bears a low or open-system p(CO2) signature. Bulk meltwaters are more likely to exhibit low p(CO2) values when suspended-sediment concentrations are high, which promotes post-mixing reactions. This conceptual model suggests that the composition of both quick flow and delayed flow is likely to be temporally variable, since kinetic, rather than equilibrium, factors determine the composition.

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33

Tranter, Martyn, Giles Brown, Robert Raiswell, Martin Sharp, and Angela Gurnell. "A conceptual model of solute acquisition by Alpine glacial meltwaters." Journal of Glaciology 39, no. 133 (1993): 573–81. http://dx.doi.org/10.3189/s0022143000016464.

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Анотація:

AbstractSolute acquisition by Alpine glacial meltwaters is the result of the coupling of different pairs of reactions, one of which usually involves dissolved gases. Hence, the availability of atmospheric gases to solution is an important control on the composition of glacial meltwaters. The chemical compositions of the two main components of the bulk meltwater, quick flow and delayed flow, are dominated by different geochemical processes. Delayed flow waters are solute-rich and exhibit high p(CO2) characteristics. The slow transit of these waters through a distributed drainage system and the predominance of relatively rapid reactions, such as sulphide oxidation and carbonate dissolution, in this environment maximize solute acquisition. Quick-flow waters are dilute, both because of their rapid transit through ice-walled conduits and open channels, and because the weathering reactions are fuelled by relatively slow gaseous diffusion of (CO2) into solution, despite solute acquisition being dominated by rapid surface exchange reactions. As a consequence, quick flow usually bears a low or open-system p(CO2) signature. Bulk meltwaters are more likely to exhibit low p(CO2) values when suspended-sediment concentrations are high, which promotes post-mixing reactions. This conceptual model suggests that the composition of both quick flow and delayed flow is likely to be temporally variable, since kinetic, rather than equilibrium, factors determine the composition.

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34

Ait Oumeziane, A., and J.-D. Parisse. "Dynamics of UV short pulse laser-induced plasmas from a ceramic material “titanium carbide”: a hydrodynamical out of equilibrium investigation." Laser and Particle Beams 37, no. 01 (March 2019): 86–100. http://dx.doi.org/10.1017/s0263034619000168.

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AbstractThe present work is motivated by the numerous applications of short lasers–ceramics interaction. It aims at applying a newly developed model to investigate the dynamic of laser-induced plasmas from a ceramic material into a helium gas under atmospheric pressure. To have a better understanding of the link between the material properties, the plume characteristics and its interaction with the laser beam, a thorough examination of the entire ablation processes is conducted. Comparison with the behavior of laser-induced plumes under the same conditions from a pure material is shown to have a key role in shedding the light on what monitors the plume expansion in the background environment. Plume temperatures, velocities, ionization rates as well as elemental composition have been presented and compared under carefully chosen relevant conditions. This study is of interest for laser matter applications depending on the induced plasmas dynamics and composition.

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35

Mykhailyk, V. A., T. V. Korinchevska, D. M. Korinchuk, and V. L. Dakhnenko. "THERMAL ANALYSIS OF GRANULAR BIOFUEL TORIFIED IN THE ATMOSPHERE OF ITS OWN GASEOUS ENVIRONMENT." Thermophysics and Thermal Power Engineering 41, no. 4 (December 24, 2019): 70–77. http://dx.doi.org/10.31472/ttpe.4.2019.10.

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The article substantiates the need to study the torrefaction of fuel from biomass in the atmosphere of its own gaseous medium formed during the thermal decomposition of organic substances. The methodology, equipment and devices for heat treatment of pine wood pellets are given. The results of a study using the TGA and DTA methods of the degree of thermal decomposition, equilibrium humidity, ash content and specific heat of thermal decomposition of torrefied at 250, 270 and 290 °С and the initial biofuel are presented. It is shown that an increase in the heat treatment temperature leads to an increase in the degree and temperature range of fuel decomposition, an increase in the specific heat of thermal decomposition, a decrease in hydrophilicity, and an increase in ash content. The degree of decomposition of torrefied biofuel with an increase in the treatment temperature within the indicated limits decreased from 7.81 to 4.89%, which indicates an insignificant balance of hemicellulose. Heat treatment caused an increase in hydrophobicity, which manifested itself in a 2.8-fold decrease in the equilibrium moisture content of biofuel torrefied at 290 °С. Due to the invariability of the mineral composition and the decrease in dry weight, the ash content in torrefied fuel is higher than in the original. The specific heat of thermal decomposition of biofuel torrefied at 290°С increased by 65.4% compared to the initial one. The study of the method of torrefaction of biofuels at atmospheric pressure in a gaseous environment formed in a confined space during the thermal decomposition of organic substances, showed its effectiveness and the possibility of using it for heat treatment of biomass without the use of inert gases.

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36

Peng, Xuejun, Gwendolyn M. Bebault, David D. Y. Chen, and Stephen L. Sacks. "Quantitative description of analyte migration behavior based on the dynamic complexation model in capillary electrophoresis." Canadian Journal of Chemistry 75, no. 5 (May 1, 1997): 507–17. http://dx.doi.org/10.1139/v97-059.

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A theory based on dynamic complexation is used to describe analyte migration behavior in capillary electrophoresis (CE). This theory is based on a one-phase system, instead of the commonly accepted two-phase system. The migration behavior of an analyte is described by three parameters (the electrophoretic mobility of the free analyte, the electrophoretic mobility of the analyte–additive complex, and the equilibrium constant (formation constant) that determines the fractions of the free analyte and the complex at a certain additive concentration). Varying the additive concentration shifts the equilibrium and changes the viscosity of the background electrolyte. Viscosity correction is crucial in interpreting the observed migration behavior of analytes. While electroosmotic flow in a capillary often varies from one capillary to another, the viscosity of a buffer is characteristic of the buffer composition and is constant for each buffer. The electrophoretic mobility of a certain species and the equilibrium constant are intrinsic properties and are less sensitive to changes in the environment. Understanding these relationships is indispensable in CE method development and method validation. A universal resolution equation is proposed, with a separation factor that has taken both the electrophoretic mobilities and equilibria into consideration. This resolution equation gives clear guidance for the optimization of CE separations. A group of nucleosides and their phosphates are used as analytes, and β-cyclodextrin is used as the additive in the model system studied in this paper. Both the observed analyte migration behavior and the resolution of analytes agree well with this theory. Keywords: dynamic complexation capillary electrophoresis, nucleoside and nucleotide separation, capacity factor, resolution equation, viscosity correction.

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37

Guo, Ying, Weixi Tang, Yonghong Xiang, Ming Qi, and Jingxiao Bi. "Thermodynamic research of jadeite jade at high temperatures and high pressures based on phase balance intelligent calculation." Thermal Science 23, no. 5 Part A (2019): 2659–65. http://dx.doi.org/10.2298/tsci181202155y.

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Based on the thermodynamic calculation of chemical composition and the intelligent calculation of phase equilibria, the temperature-pressure of the diagenetic environment of Burma jadeite-jade was studied, and its metamorphism was ver?ified. Firstly, the Wkj value and activity of the four end-member of jadeite (Jd), augite (Acm), diopsite (Di), and hedenbergite (Hed) were calculated. Jadeite rock system was simplified as NCFMASH, and the equilibrium temperature-pressure conditions of both the combination of quartz and jadeite, sodium-feldspar with little kyanite, and the combination of jadeite diopside, hedenbergite, kyanite, sodium-tremolite, tremolite and oblique zoisite were revealed as 751?C with 17.0 kb, and 631?C with 18.8 kb. Based on the two kinds of mineral combination with a small amount of sodium mica [Pa], the balance of the system temperature should be in the range from 700-770?C, and balanced pressure-range should be in the range from 17.34-18.83 kb, which reflects the pure NCFMASH system hard rock type jadeite-jade rock formation of the real balance temperature-pressure range. It is concluded that the metamorphism of jadeite rock has a stable growth equilibrium temperature-pressure range, which is the reaction interval of the closed system NCTNASH. It is explained that the reason that synthetic jadeite-jade reaches the gem level is that it has not been simulated as a mineral assemblage in the later stage and it will be subjected to multi-phase dynamic metamorphism after the rock forms, so it is unreasonable that jadeite synthesize is not just from one mineral crystals.

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LÓPEZ, RAMÓN. "Trade reform and environmental externalities in general equilibrium: analysis for an archetype poor tropical country." Environment and Development Economics 5, no. 4 (October 2000): 377–404. http://dx.doi.org/10.1017/s1355770x00000243.

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This paper provides a conceptual and empirical general equilibrium framework for the analysis of the impact of trade reform on welfare and the environment. The analysis is applied to Côte d'Ivoire explicitly considering externalities affecting biomass (natural vegetation), which is shown to be an important factor determining agricultural productivity.The simulation general equilibrium analysis shows that the agricultural output composition effect dominates the agricultural expansion effect for the case of complete trade liberalization. Thus, in this case trade liberalization causes a significant improvement in the rural biomass stock by cutting land area cultivated, increases agricultural productivity, and induces dramatic welfare gains. That is, trade liberalization is a win–win type of policy in this case. However, partial trade liberalization that only reduces protection to non-agricultural goods (and does not reduce tariffs to agricultural import substitutes and does not reduce export taxes) causes a further deterioration of the biomass resources and reduces welfare.

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39

Simone, Marco, Federica Barontini, Cristiano Nicolella, and Leonardo Tognotti. "Assessment of syngas composition variability in a pilot-scale downdraft biomass gasifier by an extended equilibrium model." Bioresource Technology 140 (July 2013): 43–52. http://dx.doi.org/10.1016/j.biortech.2013.04.052.

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40

Moroz, Mykola, Fiseha Tesfaye, Pavlo Demchenko, Myroslava Prokhorenko, Nataliya Yarema, Daniel Lindberg, Oleksandr Reshetnyak, and Leena Hupa. "The Equilibrium Phase Formation and Thermodynamic Properties of Functional Tellurides in the Ag–Fe–Ge–Te System." Energies 14, no. 5 (February 28, 2021): 1314. http://dx.doi.org/10.3390/en14051314.

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Equilibrium phase formations below 600 K in the parts Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 of the Fe–Ag–Ge–Te system were established by the electromotive force (EMF) method. The positions of 3- and 4-phase regions relative to the composition of silver were applied to express the potential reactions involving the AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 compounds. The equilibrium synthesis of the set of phases was performed inside positive electrodes (PE) of the electrochemical cells: (−)Graphite ‖LE‖ Fast Ag+ conducting solid-electrolyte ‖R[Ag+]‖PE‖ Graphite(+), where LE is the left (negative) electrode, and R[Ag+] is the buffer region for the diffusion of Ag+ ions into the PE. From the observed results, thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 were experimentally determined for the first time. The reliability of the division of the Ag2Te–FeTe2–F1.12Te–Ag2Te and Ag8GeTe6–GeTe–FeTe2–AgFeTe2–Ag8GeTe6 phase regions was confirmed by the calculated thermodynamic quantities of AgFeTe2, Ag2FeTe2, and Ag2FeGeTe4 in equilibrium with phases in the adjacent phase regions. Particularly, the calculated Gibbs energies of Ag2FeGeTe4 in two different adjacent 4-phase regions are consistent, which also indicates that it has stoichiometric composition.

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41

Li, Hai Feng. "QoS-Aware Web Services Composition: A Cooperate Optimization Approach." Key Engineering Materials 467-469 (February 2011): 69–74. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.69.

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Existing Web service optimal combination approach is mainly focused on single tasks using “selfish” behavior to pursue optimal solutions. This causes conflicts because many concurrent tasks compete for limited optimal resources, reducing service quality in services. With the best reply function of quantified task conflicts and game theory as bases, this paper establishes a mathematical model depicting the competitive relationship between multitasks and Web service under QoS constraints, and guarantees that every task can obtain optimal utility services considering other task combination strategies. Moreover, an iterative algorithm which reaches the Nash equilibrium is also proposed, and all tasks attain utility optimization under conflicting environments. Experimental analyses show that the approach can considerably enhance the actual utility of all tasks compared with existing Web services combinatorial methods.

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42

Chern, Shyh-Ming, L. T. Fan, and W. P. Walawender. "Analytical calculation of equilibrium gas composition in a CHO-inert system." AIChE Journal 35, no. 4 (April 1989): 673–75. http://dx.doi.org/10.1002/aic.690350421.

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43

Unsworth, J. F., and H. Dorans. "Thermodynamic data for dioxins from molecular modelling computations: Prediction of equilibrium isomer composition." Chemosphere 27, no. 1-3 (July 1993): 351–58. http://dx.doi.org/10.1016/0045-6535(93)90312-s.

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44

Nunes, Eduardo Z., Azarias M. de Andrade, and Ananias F. Dias Júnior. "Production of briquettes using coconut and eucalyptus wastes." Revista Brasileira de Engenharia Agrícola e Ambiental 23, no. 11 (November 2019): 883–88. http://dx.doi.org/10.1590/1807-1929/agriambi.v23n11p883-888.

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ABSTRACT This research analyzed the production and characteristics of briquettes composed of residues of Cocos nucifera and Eucalyptus pellita wood. A completely randomized design was used, having seven treatments and five repetitions per treatment. The treatments corresponded to waste percentages of coconut and eucalyptus residues as following: T1: 100% eucalyptus waste; T2: 20% coconut waste + 80% of eucalyptus waste; T3: 40% coconut waste + 60% of eucalyptus waste; T4: 50% coconut waste + 50% of eucalyptus waste; T5: 60% coconut waste + 40% of eucalyptus waste; T6: 80% coconut waste + 20% of eucalyptus waste; and, T7: 100% coconut waste. For the production of briquettes, 0.5% carboxymethylcellulose (CMC) was used as the binder. The mixtures were compacted under a load of 568 kgf cm-² for three minutes. After pressing, the briquettes were air-dried to the equilibrium moisture of the environment and, then, analyzed for physical, chemical and energy characteristics. The data were analyzed through analysis of variance, correlations and hierarchical cluster analysis (HCA). The briquettes produced with 100% of C. nucifera residues had the highest equilibrium moisture content, high volatile matter concentrations, and low fixed carbon concentrations. The basic density, the apparent specific mass and the burning rate were not affected by the composition and by the equilibrium moisture of the briquettes.

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45

Petralia, A., E. Alei, G. Aresu, D. Locci, C. Cecchi-Pestellini, G. Micela, R. Claudi, and A. Ciaravella. "A systematic study of CO2 planetary atmospheres and their link to the stellar environment." Monthly Notices of the Royal Astronomical Society 496, no. 4 (July 8, 2020): 5350–59. http://dx.doi.org/10.1093/mnras/staa1929.

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ABSTRACT The Milky Way Galaxy is literally teeming with exoplanets; thousands of planets have been discovered, with thousands more planet candidates identified. Terrestrial-like planets are quite common around other stars, and are expected to be detected in large numbers in the future. Such planets are the primary targets in the search for potentially habitable conditions outside the Solar system. Determining the atmospheric composition of exoplanets is mandatory to understand their origin and evolution, as atmospheric processes play crucial roles in many aspects of planetary architecture. In this work we construct and exploit a 1D radiative transfer model based on the discrete-ordinates method in plane-parallel geometry. Radiative results are linked to a convective flux that redistributes energy at any altitude producing atmospheric profiles in radiative–convective equilibrium. The model has been applied to a large number (6250) of closely dry synthetic CO2 atmospheres, and the resulting pressure and thermal profiles have been interpreted in terms of parameter variability. Although less accurate than 3D general circulation models, not properly accounting for e.g. clouds and atmospheric and ocean dynamics, 1D descriptions are computationally inexpensive and retain significant value by allowing multidimensional parameter sweeps with relative ease.

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46

Sudheer, A. K., and R. Rengarajan. "Time-resolved inorganic chemical composition of fine aerosol and associated precursor gases over an urban environment in western India: Gas-aerosol equilibrium characteristics." Atmospheric Environment 109 (May 2015): 217–27. http://dx.doi.org/10.1016/j.atmosenv.2015.03.028.

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47

Pazdur, Anna, Tomasz Goslar, Mirosława Pawlyta, Helena Hercman, and Michał Gradziński. "Variations of Isotopic Composition of Carbon in the Karst Environment from Southern Poland, Present and Past." Radiocarbon 41, no. 1 (1999): 81–97. http://dx.doi.org/10.1017/s0033822200019354.

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We describe a comprehensive study of carbon isotopes in several karst springs and their environs in a contemporary karst environment in the region of the Cracow-Wieluñ Upland and Western Tatra Mountains, Southern Poland. We collected samples of water, plants and carbonate deposited on aquatic plants, and obtained 13C values and 14C concentrations. We also investigated a group of the youngest calcium carbonates from caves where deposition is still being observed or ceased no more than a few hundred years ago. The determination of a 14C dilution factor (q) in these carbonates allows us to determine the “true” radiocarbon ages of old speleothems from caves in the area under investigation and enables the use of old speleothems as suitable material for extending the 14C calibration time scale, the “Absolute” age having been determined by U/Th or amino acid racemization (AAR) dating methods. Measurements of δ13C and 14C concentrations were made on dissolved inorganic carbon (DIC) extracted from water samples. Calculated values of q range from 0.55 to 0.68 and δ13C values range from −10% to −13% versus VPDB with mean values equal to 0.65 and −12%, respectively. Results indicate that the dissolution process of limestone bedrock is a closed system with the dominating contributor being biogenic carbon dioxide.Isotopic composition of carbon in contemporary plants collected at the karstic springs at 3 localities is highly diverse, with different species distinctly varying in both q and δ13C values. Extremely light values of 13C (under −40%), observed in Algae and Hyloconium splendens, are correlated with 14C concentrations that are much lower than 100 pMC. Small systematic changes of isotopic composition were found in plants of the same species collected along streams at various distances from the spring. The youngest calcium carbonates from different caves show a relatively high scatter of both δ13C values and 14C concentration. The lower reservoir effect for 14C is observed in samples with higher value of δ13C, indicating equilibrium conditions in the sedimentation of carbonate. Pazdur et al. (1995b) presented 14C dating results and paleoclimatic interpretation of 170 14C analyses of 89 speleothems from 41 caves obtained through 1994. Investigations continued until early 1997, during which time a speleothem, JWi2, was dated by 14C, U/Th and AAR dating methods, and its stable isotope composition (δ13C and δ18O) analyzed in detail (reported here). Carbon isotope analyses indicate very large differences among results obtained by U/Th, AAR, and 14C dating methods.

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48

Rogerson, P. A., and D. A. Plane. "The Dynamics of Neighborhood Age Composition." Environment and Planning A: Economy and Space 30, no. 8 (August 1998): 1461–72. http://dx.doi.org/10.1068/a301461.

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In this paper we investigate the changing demography of neighborhoods. We focus upon the dynamics of the age structure of neighborhoods, paying particular attention to the roles of (a) the magnitude of mobility and (b) the age composition of in-migrants and out-migrants. A model for studying the changing age composition of neighborhoods is developed, and alternative scenarios characterized by the nature of in-movement and out-movement are examined to make statements about the age of householders in neighborhoods. We find that high rates of mobility may serve to bring about a relatively youthful equilibrium age structure quite rapidly, whereas low rates lead to a higher mean age and to damped harmonic fluctuations both in the mean age of householders and in the magnitude of the age heterogeneity of the neighborhood. In addition, we compare the evolutions of age structure in neighborhoods with age patterns of in-movement and out-movement that could typify areas of renters and areas of homeowners.

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Lopez-Ortiz, A., V. Collins-Martinez, and D. P. Harrison. "SER Process Variable Evaluation for the Production of Hydrogen using Calcined Dolomite." Journal of New Materials for Electrochemical Systems 14, no. 2 (April 7, 2011): 121–26. http://dx.doi.org/10.14447/jnmes.v14i2.120.

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Reaction performance of the sorption enhanced reforming (SER) process for the production of hydrogen was studied using commercial dolomite as inexpensive solid CO2 absorbent. The combined reforming, shift, and CO2 separation reactions were studied using a laboratory-scale fixed-bed reactor as a function of temperature, feed gas composition, dolomite type, and dolomite and catalyst particle sizes. Reactor was loaded with a mixture of calcined dolomite (≈ 23g) and a commercial reforming catalyst (NiO/Al2O3, ≈ 10g). Temperature was varied from 550 to 650°C at 15 atm. Feed gas composition was varied from 6 to 20% CH4/balance N2 and steam, with a feed H2O/CH4 ratio = 4. Two sources of dolomite were used; Rockwell and Stonelite. Particle sizes of dolomite and catalyst were 75>dp>150 μm and 300>dp>425 μm, respectively and were inversely varied. Results show that at 550°C Ca(OH)2 formation is possible, thus reducing the available CaO for carbonation, negatively affecting the performance of the SER system, while 650°C reached the SER thermodynamic equilibrium (TE). The use of dolomite approached the TE of the feed gas compositions studied, disregarding of its source. Kinetic effects observed in the tests suggest that small dolomite and large catalyst particles favor the decrease of CO2 diffusion effects.

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Log, Torgrim, and Asgjerd Moi. "Ethanol and Methanol Burn Risks in the Home Environment." International Journal of Environmental Research and Public Health 15, no. 11 (October 26, 2018): 2379. http://dx.doi.org/10.3390/ijerph15112379.

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Анотація:

Biofuel heaters and fireplaces have in recent years been introduced for indoor and outdoor use. Due to their simplicity, they are usually equipped with few or no safety features. Worldwide, incidents resulting in major skin burn injury and long hospitalization periods have occurred when using such biofuel units. The present study analyses the characteristics of the liquids ethanol and methanol to get a scientific background for understanding related accidents. The comparably heavy vapors, especially from ethanol, may generate a pillow of combustible gas in the vicinity of the unit, particularly in quiescent indoor air conditions. It is also revealed that these fuels represent a potential severe risk, since the equilibrium vapor pressures are close to the stoichiometric fuel–air composition at normal room temperatures. Selected incidents were reviewed to understand the mechanisms involved when severe burns were received by the users. It turns out that the most severe incidents were related to refilling operations and included ignition of the fuel container vapor phase. When ignited, the container gas phase expansion propelled burning fuel from the bottle or container onto the user or other persons in the vicinity. Similar incidents involving refilling methanol for chemistry demonstrations and ethanol for endodontic (dentistry) treatment were also studied and it was shown that these accidents followed similar accident mechanisms. It may be concluded that the main contributors to burn risk are the near-stoichiometric vapor pressure of these liquids at room temperature and the close proximity of the fuel container to burning fuel. Research needs and possible technical barriers are suggested to reduce this risk for the future.

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