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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 47 (1955), S. 2066-2072 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 7 (1986), S. 771-780 
    ISSN: 0392-6737
    Keywords: Surface processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Si è studiata la diffusione di MgCl2 attraverso sei diversi tipi di membrane Nuclepore di policarbonato. Il cambiamento di concentrazione nel tempo è stato determinato da un misuratore di conduttività collegato con un microcomputer. Le misurazioni sono state effettuate a temperatura tra 20 e 50°C ad intervalli di 10°C e a differenti concentrazioni nell’intervallo 2·10−4÷10−1 equiv l−1. La permeabilità al saleP ms del sistema membrana, formato dalla membrana stessa e da due strati adiacenti di diffusione è ottenuta attraverso la trattazione matematica dei risultati di concentrazionivs. il tempo. Si sono studiate la variazioneP ma con la concentrazione delle soluzioni, le caratteristiche della membrana e la temperatura. Infine si è stimata l’energia di attivazione del processo di diffusione usando un modello cinetico di permeazione.
    Abstract: Резюме Исследуется диффузия MgCl2 через шесть различных типов ядерных мембран из поликарбоната. Изменение концентрации со временем определяется с помощью измерения проводимости в линию с микрокомпьютером. Измерения проводятся при температурах от 20 до 50°C с интервалом 10°C и при различных концентрациях в области 2.10−4÷10−1. Проницаемость солиP ms через мембранную систему, образованную самой мембраной и двумя соседними слоями диффузии, получается с помощью математической обработки зависимости концентрации от времени. Мы исследовали изменениеP ms в зависимости от концентрации растворов, характеристик мембран и температуры. Б заключение, мы оцениваем энергию активации процесса диффузии, используя кинетическую модель проникновения.
    Notes: Summary Diffusion of MgCl2 through six different types of nuclepore membranes of polycarbonate has been studied. The change of concentration with time was determined by a conductivitymeter on line with a microcomputer. The measurements were carried out at temperatures between 20 and 50°C at 10°C intervals and at different concentrations in the range 2·10−4÷10−1 equiv l−1. The salt permeabilityP ms of the membrane system, formed by the membrane itself and the two adjacent layers of diffusion, is obtained through methematical treatment of the concentrationvs. time results. We have studied the variation ofP ms with concentration of solutions, the characteristics of the membrane and the temperature. Finally, we have estimated the activation energy of the diffusion process by using a kinetic model of the permeation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 9 (1987), S. 174-184 
    ISSN: 0392-6737
    Keywords: Surface processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Sono stati studiati coefficienti apparenti di diffusione ionica attraverso membrane di policarbonato magnate da due soluzioni di elettroliti a partire dall’equazione di Nernst-Planck usando l’assunto di campo elettrico costante. Da questi coefficienti di diffusione abbiamo anche determinato il numero di trasporto di cationi attraverso le membrane. Si sono considerate sei diverse membrane e due elettroliti (LiCl e MgCl2), alla temperatura di 20°C e per concentrazioni nell’intervallo (10−3÷10+1) mol l−1.
    Abstract: Резюме Используя предположения о постоянном электрическом поле, на основе уравнения Нернста-Планка исследуются ионные коэффициенты диффузии через поликарбанатные мембраны, омываемые двумя электролитическими растворами. Из этих коэффициентов диффузии мы также определяем транспорт катионов через эти мембраны. Были рассмотрены шесть различных мембран и два электролита (LiCl и MgCl2) при температуре 20°C и для концентраций в области (10−4÷ ÷10−1) моль·л−1.
    Notes: Summary Apparent ionic diffusion coefficients across polycarbonate membranes bathed by two electrolyte solutions have been studied from Nernst-Planck equation using the assumption of constant electric field. From these diffusion coefficients we have also determined the cation transport numbers across the membranes. Six different membranes and two electrolytes (LiCl and MgCl2) have been considered, at the temperature of 20°C and for concentrations in the range (10−4÷10−1) mol l−1.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-072X
    Keywords: Key words Protein phosphorylation ; ATP-Pi exchange ; Light-harvesting complexes ; Reaction center ; Photosynthesis ; Photomorphogenesis ; Membrane ; growth ; Polypeptide insertion ; Phospho-amino esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Membranes of Rhodobacter capsulatus strain U43 (pTX35) showed qualitatively very similar phosphorylation patterns under in vitro and in vivo conditions. In vitro, it was irrelevant whether the phosphate source was orthophosphate or ATP. Inhibitors of electron transport did not inhibit light-harvesting complex I (LHIα) (B870) polypeptide phosphorylation, except for o-phenanthroline, which was strongly inhibitory. Redox conditions regulated the amount of protein phosphorylated; external redox potentials between +200 and +300 mV promoted the reaction. Phosphorylation was inhibited by uncouplers such as carbonyl cyanide m-chlorophenyl hydrazone and nigericin plus valinomycin plus potassium ions. Inhibitors of the H+-ATPase were also inhibitory when the phosphate source was [32P]Pi or [γ-32P]ATP. From these results, it was concluded that an operative reaction center, a coupled membrane, and external redox potentials higher than +200 mV are required for optimum LHIα phosphorylation. We also demonstrated that phosphorylation of LHIα polypeptide occurs before insertion into the membrane and that phosphate is preferentially incorporated into specific domains within the cytoplasmic membrane. Intracytoplasmic membranes, identified here as light membranes, were found to contain a dephosphorylated LHIα polypeptide.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1191-1200 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Dans le present article on considére un nouveau modèle pour le transport moléculaire à travers des membranes, qui a été introduit antérieurement par Hosur. Dans ce modèle, la membrane est assimilée à une barrière de potentiel, en déterminant le flux matériel à travers de la měme partant dès le coefficient de transmission de la barrière, en supposant l'existence d'une différence d'énergie parmi les molécules qui appartiennent à les fluides d'une et d'autre cǒté de la membrane. On obtient ainsi, une expression pour le flux dans le cas de pétites différences d'énergie, qui a été particularisée au cas ou la difference d'énergie est due à un gradient de température, un gradient de concentration ou à tous les deux gradients agissant ensemble. Dans tous les cas, sous certaines conditions, on obtient des equations qui sont formellement identiques à celles obtenues par la thermodynamique des processus irréversibles.
    Abstract: In vorliegendem Artikel wird ein von Hosur eingeführtes Modell für Transport durch Membranen untersucht. In diesem Modell wird die Membran mit einer Potentialschwelle assimiliert, und der Materialfluss durch die Membran wird vom Transmissionskoeffizient der Schwelle bestimmt, wobei es wird angenommen, dass ein Energieunterschied unter den Molekülen an den beiden Seiten der Membran existiert. Für den Fall wo dieser Energieunterschied klein ist wird eine Gleichung für den Transport erhalten. Diese wird spezialisiert zu den Fallen wo der Energieunterschied von einem Temperatur-oder Konzentrationsgradient oder beiden zusammen verursacht wird. In allen Fallen werden-mit gewissen Begrenzungen-Gleichungen erhalten, die mit denen der Thermodynamik irreversibler Prozesse formal identisch sind.
    Notes: In the present paper a new model for the transport through membranes, introduced previously by Hosur, is considered. In this model, the membrane is assimilated to a potential barrier, and the material flow through the membrane is determined from the transmission coefficient of the barrier, assuming the existence of an energy difference among the molecules placed at both sides of the membrane. An equation for the transport, in the case of small energy differences, is obtained, which is particularized to the cases that the energy difference is caused by a temperature gradient, a concentration gradient, and both gradients acting together. In all cases, under certain limitations, formally identical equations to those of the thermodynamics of irreversible processes are obtained.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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