Relevant bibliographies by topics / Temperatura bivalente

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Academic literature on the topic 'Temperatura bivalente'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Temperatura bivalente"

1

Costa Câmara, Ana Paula. "PROPRIEDADES FÍSICO – MECÂNICAS E AMBIENTAL DE CERÂMICA ESTRUTURAL COM ESTABILIZAÇÃO DO ÍON MANGANÊS." HOLOS 5 (October 29, 2012): 142. http://dx.doi.org/10.15628/holos.2012.1107.

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Neste trabalho estudou-se a adição do íon manganês bivalente a uma massa argilosa do estado do Rio Grande do Norte a fim de avaliar a viabilidade tecnológica e ambiental do material cerâmico. A matéria-prima cerâmica foi caracterizada por análise química (FRX) e difratometria de raios – X (DRX). O íon metálico foi adicionado na forma de soluções aquosas nas concentrações de 100, 150 e 200 mg/L. Os corpos de prova obtidos por extrusão e sinterizados nas temperaturas de 850, 950 e 1050 °C foram avaliados por ensaios cerâmicos e ambiental de solubilidade. As propriedades tecnológicas avaliadas foram: retração linear de queima, absorção de água, porosidade aparente, massa específica aparente e tensão de ruptura à flexão em três pontos. Propriedades como porosidade aparente e absorção de água não apresentaram variações significativas em função da concentração do íon manganês. Por outro lado, a tensão de ruptura à flexão cresce com o aumento da temperatura independente da concentração do íon. Os resultados indicaram que a cerâmica com o íon manganês incorporado e estabilizado, é adequada para a fabricação de diversos produtos cerâmicos, tais como tijolo maciço e revestimento semi-poroso, sem oferecer risco ao meio ambiente.
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2

Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Study on Preferential Selectivity of Nuclear Grade Resin Indion-223 towards some Bivalent Ions." International Letters of Chemistry, Physics and Astronomy 34 (May 2014): 11–21. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.34.11.

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In the present paper attempts are made to understand the selectivity of nuclear grade cation exchange resin Indion-223 in H+ form towards Ca2+ and Mg2+ bivalent ions in the solution based on thermodynamic concept. It was observed that with rise in temperature the equilibrium constant K values for H+/Ca2+ uni-bivalet ion exchange reactions increases from 0.000397 to 0.000639. Similarly for H+/Mg2+ uni-bivalet ion exchange reactions the equilibrium constant K values increases from 0.000177 to 0.000333. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 38.92 and 51.46 kJ/ mol respectively. The difference in K values and enthalpy values were used to predict the selectivity behaviour of the resin towards the Ca2+ and Mg2+ bivalent ions in the solution. The thermodynamic concept of the present study can be applied to understand the selectivity behaviour of different nuclear as well as non-nuclear grade resins towards wide range of ionic species present in the exchanging liquid medium.
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Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Comparative Study of Uni-Univalent H+/Na+ and Uni-Bivalent H+/Ca2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 2014): 127–35. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.33.127.

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The present paper deals with the ion exchange equilibrium studies of uni-univalent and uni-bivalent ion exchange reactions using nuclear grade anion exchange resin Indion-223 in H+ form towards Na+ and Ca2+ ions in the solution. It was observed that with rise in temperature the equilibrium constants K values for H+/Na+ uni-univalet ion exchange reaction increases from 0.01389 to 0.01855. Similarly for H+/Ca2+ uni-bivalet ion exchange reaction the equilibrium constants K values increases from 0.000397 to 0.000639. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 38.92 kJ/ mol respectively.
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4

Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Thermodynamics of Uni-Univalent H+/K+ and Uni-Bivalent H+/Ca2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 2014): 190–98. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.33.190.

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The present paper deals with the thermodynamic of uni-univalent and uni-bivalent ion exchange reactions using nuclear grade anion exchange resin Indion-223. It was observed that with rise in temperature the equilibrium constants K values for H+/K+ uni-univalet ion exchange reaction increases from 0.01710 to 0.02374. Similarly for H+/Ca2+ uni-bivalet ion exchange reaction the equilibrium constants K values increases from 0.000397 to 0.000639. The increase in K values with rise in temperature for both the reactions indicates its endothermic nature having the enthalpy change values of 22.72 and 38.92 kJ/ mol respectively. The technique used here can be extended further to standardise the process parameters in order to bring about the efficient separation of the desired ionic species from the solution
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5

Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Ion Exchange Equilibrium Studies of Uni-Univalent H+/Na+ and Uni-Bivalent H+/Mg2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 2014): 199–207. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.33.199.

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In the present investigation the uni-univalent and uni-bivalent ion exchange reactions were studied using nuclear grade anion exchange resin Indion-223 in H+ form. It was observed that for H+/Na+ uni-univalet ion exchange reaction, with rise in temperature the equilibrium constants K values increases from 0.01389 to 0.01855. Similarly increase in K values was observed from 0.000177 to 0.000333 for H+/Mg2+ uni-bivalet ion exchange reaction. The increase in equilibrium constant values with rise in temperature indicate endothermic ion exchange reactions having the enthalpy change values of 25.55 and 51.46 kJ/ mol respectively. It is expected that the present study will provide valuable information in order to decide about the selection of those resins for efficient separation of various ionic species present in the industrial waste water effluents.
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Singare, Pravin U., Akmal L. Khan Mohammed, and N. N. Dixit. "Study of Uni-Univalent H+/K+ and Uni-Bivalent H+/Mg2+ Ion Exchange Reactions Using Nuclear Grade Resin Indion-223." International Letters of Chemistry, Physics and Astronomy 33 (May 2014): 231–39. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.33.231.

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In the present paper the uni-univalent and uni-bivalent ion exchange reactions were investigated using nuclear grade anion exchange resin Indion-223 in H+ form. For both H+/K+ uni-univalet ion exchange reactions and H+/Mg2+ uni-bivalet ion exchange reactions, the equilibrium constant K values increases from 0.01710 to 0.02374 and from 0.000177 to 0.000333 respectively as the reaction temperature rises from 35.0 °C to 45.0 °C. The increase in K values with temperature suggest endothermic ion exchange reactions having the enthalpy change values of 22.72 and 51.46 kJ/ mol respectively. The results of such studies will help in selection of suitable ion exchange resins in order to bring about efficient separation of different ionic species present in the waste water effluents released from nuclear as well as chemical process industries.
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7

Kopyto, Renata, Charles F. Crane, and David A. Sleper. "Effect of temperature on meiosis and fertility in Festuca mairei × Festuca arundinacea var. glaucescens." Genome 32, no. 4 (August 1, 1989): 708–18. http://dx.doi.org/10.1139/g89-501.

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This study considered the effects of three continuous growth temperatures (14, 21, and 28 °C) on apparent genomic structure, apparent chromosome arm ratio, pollen abortion, and meiotic nonreduction in full-sib genotypes of Festuca mairei × F. arundinacea var. glaucescens. Ten genotypes were sampled for meiosis and 20 for pollen. The metaphase I (MI) data for each sampled combination of genotype, temperature, and replication were subjected to a bootstrap algorithm that calculated 95% confidence limits for each class of meiotic figure and for the ratio of ring bivalents to total bivalents, the total number of chromosomes in multivalents per cell, and the mean arm-binding frequency. These confidence limits permitted an evaluation of the significance of differences among genotypes, temperatures, and replications. The MI data were also subjected to two types of numerical models to investigate apparent genomic structure and mean effective chromosome arm ratio, i.e., pairing regulation and extent of chiasma interference across the centromere. The hybrids overall exhibited a 2:2 (AABB) genomic structure, but there were significant differences among genotypes in arm-binding frequency and frequencies of univalents, rod bivalents, and ring bivalents. Except for desynapsis and impaired chromosome contraction in one genotype at 28 °C, temperature had little effect; optimized genomic structure was slightly more 2:1:1 (like AABC) at 14 °C and chiasma interference increased slightly at 28 °C. One genotype was monosomic but meiotically normal. Pollen stainability was significantly depressed at 14 °C, while microspore micronuclei were more numerous. Pollen diameter was least at 21 °C regardless of degree of abortion.Key words: meiosis, meiotic modeling, temperature, pollen fertility, Festuca.
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8

Doseva, Nadezhda, and Daniela Chakyrova. "Life cycle cost analysis of different residential heat pump systems." E3S Web of Conferences 207 (2020): 01014. http://dx.doi.org/10.1051/e3sconf/202020701014.

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Nowadays, the application of air-source heat pumps for heating and cooling in residential buildings has been increased significantly. The main occasion for this is the accessibility of a heat source for these devices - the external air. Nevertheless, the increase of the energy efficiency of the air source heat pump systems is a difficult design problem because their capacity and performance are a function of the dynamically changing parameters of the outdoor air. Because of that, the main aim of this study is to develop an approach for choosing a structural scheme of an air-to-water heat pump system under specific climatic conditions. The considered systems are monovalent, bivalent-parallel and bivalent-alternative heat pump systems. In the current paper is conducted a dynamic energy modeling of heating and cooling demand of a typical residential building situated in Varna, Bulgaria and applying the bin temperature data. It is assessed the effect of the heat pump capacity over the annual and seasonal energy performance of the heat pump systems. It is established the effect of the bivalent temperature, cut-off temperature and on-off cycles duration on rates of the criteria for techno-economic assessment. The seasonal coefficient of performance (SCOP), seasonal energy efficiency rate (SEER) and life cycle costs (LCC) of the analyzed heat pump systems are adopted as assessment parameters.
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9

Demchenko, A., Y. Chang, E. Chikoidze, B. Berini, C. Lefèvre, F. Roulland, C. Ulhaq-Bouillet, et al. "Tuning the conductivity type in a room temperature magnetic oxide: Ni-doped Ga0.6Fe1.4O3 thin films." RSC Advances 6, no. 34 (2016): 28248–56. http://dx.doi.org/10.1039/c6ra01540a.

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The mechanism responsible for conduction in pulsed laser deposited thin films of room temperature ferrimagnetic Ga0.6Fe1.4O3 is fully elucidated. The conduction type can be tuned from n to p through doping with bivalent Ni ions.
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10

Shan, Yue Jin, Yoko Kanai, Keitaro Tezuka, and Hideo Imoto. "Synthesis and Electromagnetic Properties of Ca2MTeO6 (M = Mn, Co, Mg)." Advances in Science and Technology 45 (October 2006): 2572–75. http://dx.doi.org/10.4028/www.scientific.net/ast.45.2572.

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Ordered perovskite-type oxides, Ca2MTeO6 (M = Mn, Co, Mg), were synthesized by a solid-state reaction method. All of samples belonged to space group P21/n and were insulators at room temperature. However, their electronic conductivities tended large gradually with a rise of temperature. Ca2MnTeO6 and Ca2CoTeO6 showed anti-ferromagnetism, and their Neel temperatures were 10 K and 7 K, respectively. The effective magnetic moment of manganese ion was 5.8 μB while its valence was bivalence in Ca2MnTeO6.
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Dissertations / Theses on the topic "Temperatura bivalente"

1

Impalà, Veronica. "Ottimizzazione delle prestazioni energetiche di impianti ibridi a pompa di calore mediante il software TRNSYS." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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In questa tesi si è analizzata l’ottimizzazione energetica di un impianto di riscaldamento a pompa di calore variando la configurazione idraulica, il sistema di controllo, la tipologia della valvola di espansione ed il sistema di integrazione. Per confrontare le varie soluzioni impiantistiche sono state condotte numerose simulazioni dinamiche annuali, mediante il software Trnsys, con lo scopo di studiare il comportamento di tali impianti in un clima come quello di Bolzano. In questo studio si sono considerate diverse taglie della pompa di calore con integrazione a resistenza elettrica o a caldaia a gas e si sono effettuate numerose simulazioni dinamiche, al fine di determinare come varia il rendimento stagionale. Nel caso di resistenza elettrica si è imposto un funzionamento parallelo di entrambi i generatori e si è valutata l’influenza della temperatura bivalente caratteristica del sistema: al crescere della potenza della resistenza si ha un crollo delle prestazioni complessive dell’impianto. Nel caso di integrazione con caldaia si è considerato sia un funzionamento parallelo che alternativo dei generatori tenendo in conto l’influenza della temperatura di cut-off al variare della temperatura bivalente: per basse temperature di cut-off non si hanno apprezzabili variazioni di efficienza tra un sistema bivalente parallelo ed uno alternativo, viceversa le prestazioni si riducono fino ad un 10% nel caso di elevate temperature di cut-off. Per valutare la fattibilità economica degli impianti simulati è stato calcolato il VAN delle diverse soluzioni dopo un periodo di 15 anni e si è constatato che un impianto con una pompa di calore di piccola taglia e con integrazione a resistenza elettrica risulta più conveniente di un impianto che utilizza la caldaia come sistema ausiliario. Tuttavia, il beneficio economico che si trae utilizzando un sistema ibrido rispetto ad un impianto a pompa di calore monovalente varia in base al costo dell’energia elettrica e del gas.
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