Sample records for valores individuais na

  1. O peso relativo dos setores econômicos na formação do valor adicionado- uma análise à luz da teoria marxiiana

    Microsoft Academic Search

    Águida Cristina Santos Almeida

    Esta dissertação tem por objetivo investigar a importância dos setores econômicos na formação do valor adicionado. Parte de uma análise crítica das estatísticas das contas nacionais, de responsabilidade do IBGE, discutindo a metodologia dos cálculos e a teoria econômica que lhe serve de base e que fundamenta a afirmação de que o setor de serviços vem cada vez mais se

  2. O VALOR AGREGADO NA CADEIA PRODUTIVA DO COCO NA REGIÃO DO SUBMEDIO DO VALE DO SÃO FRANCISCO

    Microsoft Academic Search

    Maria Auxiliadora Primo Beserra; Waldenir S. Fagundes Britto

    2008-01-01

    Este trabalho tem como principal objetivo demonstrar, a partir dos custos de produção e de beneficiamento do coco ao longo de toda a cadeia produtiva, os valores agregados ao produto e a parcela retida por cada elo ao longo dessa cadeia. Foram usados como dados da equação o preço final pago pelo consumidor, os custos de produção agrícola e industrial,

  3. A comprehensive dairy valorization model.

    PubMed

    Banaszewska, A; Cruijssen, F; van der Vorst, J G A J; Claassen, G D H; Kampman, J L

    2013-02-01

    Dairy processors face numerous challenges resulting from both unsteady dairy markets and some specific characteristics of dairy supply chains. To maintain a competitive position on the market, companies must look beyond standard solutions currently used in practice. This paper presents a comprehensive dairy valorization model that serves as a decision support tool for mid-term allocation of raw milk to end products and production planning. The developed model was used to identify the optimal product portfolio composition. The model allocates raw milk to the most profitable dairy products while accounting for important constraints (i.e., recipes, composition variations, dairy production interdependencies, seasonality, demand, supply, capacities, and transportation flows). The inclusion of all relevant constraints and the ease of understanding dairy production dynamics make the model comprehensive. The developed model was tested at the international dairy processor FrieslandCampina (Amersfoort, the Netherlands). The structure of the model and its output were discussed in multiple sessions with and approved by relevant FrieslandCampina employees. The elements included in the model were considered necessary to optimally valorize raw milk. To illustrate the comprehensiveness and functionality of the model, we analyzed the effect of seasonality on milk valorization. A large difference in profit and a shift in the allocation of milk showed that seasonality has a considerable impact on the valorization of raw milk. PMID:23200469

  4. Il valore dei servizi ambientali delle foreste

    E-print Network

    Pettenella, Davide

    1 Il valore dei servizi ambientali delle foreste Davide Pettenella, Paola Gatto, Laura Secco, Mauro'economia della natura. La contabilità dei servizi resi dagli ecosistemi per la valorizzazione delle aree protette funzionamento degli ecosistemi e dei meccanismi di erogazione dei SE · La gran parte dei SE sono privi di un

  5. Stolen Valor: Phonies, Fakes and Frauds

    Microsoft Academic Search

    Jim Willis

    President George W. Bush signed the Stolen Valor Act into law on Dec. 20, 2006. Title 18, United States Code, Section 704 prohibits the unauthorized wearing, manufacturing or selling of all military awards. Violators of this statute face a fine of up to $100,000 and\\/or imprisonment of up to one year. Specific details regarding the sale or offering for sale

  6. Valorization of phosphogypsum as hydraulic binder.

    PubMed

    Kuryatnyk, T; Angulski da Luz, C; Ambroise, J; Pera, J

    2008-12-30

    Phosphogypsum (calcium sulfate) is a naturally occurring part of the process of creating phosphoric acid (H(3)PO(4)), an essential component of many modern fertilizers. For every tonne of phosphoric acid made, from the reaction of phosphate rock with acid, commonly sulfuric acid, about 3t of phosphogypsum are created. There are three options for managing phosphogypsum: (i) disposal or dumping, (ii) stacking, (iii) use-in, for example, agriculture, construction, or landfill. This paper presents the valorization of two Tunisian phosphogypsums (referred as G and S) in calcium sulfoaluminate cement in the following proportions: 70% phosphogypsum-30% calcium sulfoaluminate clinker. The use of sample G leads to the production of a hydraulic binder which means that it is not destroyed when immersed in water. The binder including sample S performs very well when cured in air but is not resistant in water. Formation of massive ettringite in a rigid body leads to cracking and strength loss. PMID:18433998

  7. Em dvida o valor de cortes a devolver s universidades

    E-print Network

    Instituto de Sistemas e Robotica

    Em dúvida o valor de cortes a devolver às universidades Secretário de Estado reuniu-se ontem com o a garantia de que "a muito curto prazo" se- rão entregues os 30 milhões em dívida, revelou ao JN o rei- tor verbas cortadas que são entregues em valores inferiores". "Nos próximos dias, tenho de tomar decisões

  8. Valorization of Cereal Based Biorefinery Byproducts: Reality and Expectations

    PubMed Central

    2013-01-01

    The growth of the biobased economy will lead to an increase in new biorefinery activities. All biorefineries face the regular challenges of efficiently and economically treating their effluent to be compatible with local discharge requirements and to minimize net water consumption. The amount of wastes resulting from biorefineries industry is exponentially growing. The valorization of such wastes has drawn considerable attention with respect to resources with an observable economic and environmental concern. This has been a promising field which shows great prospective toward byproduct usage and increasing value obtained from the biorefinery. However, full-scale realization of biorefinery wastes valorization is not straightforward because several microbiological, technological and economic challenges need to be resolved. In this review we considered valorization options for cereals based biorefineries wastes while identifying their challenges and exploring the opportunities for future process. PMID:23931701

  9. FALSAS ANOMALÍAS DE LA FUNCIÓN VALOR ACTUAL NETO

    Microsoft Academic Search

    Joan Pasqual; José Antonio Tarrío; María José Pérez

    2001-01-01

    Las anomalías que surgen en el cálculo y la interpretación del Valor Actual Neto (VAN) y la Tasa Interna de Rendimiento son fácilmente superables, teniendo en cuenta las propiedades reales del VAN y redefiniendo adecuadamente lo que es una inversión y un crédito

  10. Valorization of winery waste vs. the costs of not recycling

    SciTech Connect

    Devesa-Rey, R., E-mail: rosa.devesa.rey@uvigo.es [Dpt. Ingenieria Quimica, E.T.S. Ingenieros Industriales, Campus As Lagoas, Marcosende, Universidad de Vigo (Spain); Vecino, X.; Varela-Alende, J.L. [Dpt. Ingenieria Quimica, E.T.S. Ingenieros Industriales, Campus As Lagoas, Marcosende, Universidad de Vigo (Spain); Barral, M.T. [Dpt. Edafologia y Quimica Agricola, Facultad de Farmacia, Campus Sur, Universidad de Santiago de Compostela (Spain); Cruz, J.M.; Moldes, A.B. [Dpt. Ingenieria Quimica, E.T.S. Ingenieros Industriales, Campus As Lagoas, Marcosende, Universidad de Vigo (Spain)

    2011-11-15

    Graphical abstract: Highlights: > Lactic acid, biosurfactants, xylitol or ethanol may be obtained from wine residues. > By-products valorization turns wine wastes into products with industrial applications. > The costs of waste disposal enhances the search of economically viable solutions for valorizing residues. - Abstract: Wine production generates huge amounts of waste. Before the 1990s, the most economical option for waste removal was the payment of a disposal fee usually being of around 3000 Euros. However, in recent years the disposal fee and fines for unauthorized discharges have increased considerably, often reaching 30,000-40,000 Euros, and a prison sentence is sometimes also imposed. Some environmental friendly technologies have been proposed for the valorization of winery waste products. Fermentation of grape marc, trimming vine shoot or vinification lees has been reported to produce lactic acid, biosurfactants, xylitol, ethanol and other compounds. Furthermore, grape marc and seeds are rich in phenolic compounds, which have antioxidants properties, and vinasse contains tartaric acid that can be extracted and commercialized. Companies must therefore invest in new technologies to decrease the impact of agro-industrial residues on the environment and to establish new processes that will provide additional sources of income.

  11. Valorization of humin-based byproducts from biomass processing-a route to sustainable hydrogen.

    PubMed

    Hoang, Thi Minh Chau; Lefferts, Leon; Seshan, K

    2013-09-01

    The synthesis of biomass-based top value-added chemical platforms, for example, 5-hydroxymethyl furfural, furfural, or levulinic acid from the acid-catalyzed dehydration of sugars results in high yields of insoluble by-products, referred to as humin. Valorization of humin by steam reforming for H2 is discussed. Both thermal and catalytic steam gasification were investigated systematically. Humin undergoes drastic changes under thermal pre-treatment to the gasification temperature. Alkali-metal-based catalysts were screened for the reactions. Na2 CO3 showed the highest activity and was selected for further study. The presence of Na2 CO3 enhances the gasification rate drastically, and gas-product analysis shows that the selectivity to CO and CO2 is 75% and 25%, respectively, which is a H2 /CO ratio of 2 (corresponding to 81.3% H2 as compared to the thermodynamic equilibrium). A possible process for the complete, efficient conversion of humin is outlined. PMID:23939662

  12. A proposed new framework for valorization of geoheritage in Norway

    NASA Astrophysics Data System (ADS)

    Dahl, Rolv; Bergengren, Anna; Heldal, Tom

    2015-04-01

    The geological history of Norway is a complex one, . The exploitation of geological resources of different kinds has always provided the backbone of the Norwegian community. Nevertheless, the perception of geology and the geological processes that created the landscape is little appreciated, compared to bio-diversity and cultural heritage. Some geological localities play an important role in our perception and scientific understanding of the landscape. Other localities are, or could be, important tourist destinations. Other localities can in turn be important for geoscience education on all levels, whereas other plays a major role in the understanding of geodiversity and geoheritage and should be protected as natural monuments. A database based on old registrations has been compiled and a web mapping server is recently launched based on old and new registrations. However, no systematical classification and identification of important sites has been done for the last thirty years. We are now calling for a crowdsourcing process in the geological community in order to validate and valorize the registrations, as well as defining new points and areas of interest. Furthermore, we are developing a valorization system for these localities. The framework for this system is based on studies from inventories in other countries, as well as suggestions from ProGeo. The aim is to raise awareness of important sites, and how they are treated and utilized for scientific, or educational purposes, as tourist destinations or heritage sites. Our presentation will focus on the development of the framework and its implications.

  13. Valorization of Sargassum muticum Biomass According to the Biorefinery Concept

    PubMed Central

    Balboa, Elena M.; Moure, Andrés; Domínguez, Herminia

    2015-01-01

    The biorefinery concept integrates processes and technologies for an efficient biomass conversion using all components of a feedstock. Sargassum muticum is an invasive brown algae which could be regarded as a renewable resource susceptible of individual valorization of the constituent fractions into high added-value compounds. Microwave drying technology can be proposed before conventional ethanol extraction of algal biomass, and supercritical fluid extraction with CO2 was useful to extract fucoxanthin and for the fractionation of crude ethanol extracts. Hydrothermal processing is proposed to fractionate the algal biomass and to solubilize the fucoidan and phlorotannin fractions. Membrane technology was proposed to concentrate these fractions and obtain salt- and arsenic-free saccharidic fractions. Based on these technologies, this study presents a multipurpose process to obtain six different products with potential applications for nutraceutical, cosmetic and pharmaceutical industries. PMID:26110896

  14. Lignin valorization: improving lignin processing in the biorefinery.

    PubMed

    Ragauskas, Arthur J; Beckham, Gregg T; Biddy, Mary J; Chandra, Richard; Chen, Fang; Davis, Mark F; Davison, Brian H; Dixon, Richard A; Gilna, Paul; Keller, Martin; Langan, Paul; Naskar, Amit K; Saddler, Jack N; Tschaplinski, Timothy J; Tuskan, Gerald A; Wyman, Charles E

    2014-05-16

    Research and development activities directed toward commercial production of cellulosic ethanol have created the opportunity to dramatically increase the transformation of lignin to value-added products. Here, we highlight recent advances in this lignin valorization effort. Discovery of genetic variants in native populations of bioenergy crops and direct manipulation of biosynthesis pathways have produced lignin feedstocks with favorable properties for recovery and downstream conversion. Advances in analytical chemistry and computational modeling detail the structure of the modified lignin and direct bioengineering strategies for future targeted properties. Refinement of biomass pretreatment technologies has further facilitated lignin recovery, and this coupled with genetic engineering will enable new uses for this biopolymer, including low-cost carbon fibers, engineered plastics and thermoplastic elastomers, polymeric foams, fungible fuels, and commodity chemicals. PMID:24833396

  15. Valorization of Sargassum muticum Biomass According to the Biorefinery Concept.

    PubMed

    Balboa, Elena M; Moure, Andrés; Domínguez, Herminia

    2015-01-01

    The biorefinery concept integrates processes and technologies for an efficient biomass conversion using all components of a feedstock. Sargassum muticum is an invasive brown algae which could be regarded as a renewable resource susceptible of individual valorization of the constituent fractions into high added-value compounds. Microwave drying technology can be proposed before conventional ethanol extraction of algal biomass, and supercritical fluid extraction with CO2 was useful to extract fucoxanthin and for the fractionation of crude ethanol extracts. Hydrothermal processing is proposed to fractionate the algal biomass and to solubilize the fucoidan and phlorotannin fractions. Membrane technology was proposed to concentrate these fractions and obtain salt- and arsenic-free saccharidic fractions. Based on these technologies, this study presents a multipurpose process to obtain six different products with potential applications for nutraceutical, cosmetic and pharmaceutical industries. PMID:26110896

  16. Lignin valorization through integrated biological funneling and chemical catalysis.

    PubMed

    Linger, Jeffrey G; Vardon, Derek R; Guarnieri, Michael T; Karp, Eric M; Hunsinger, Glendon B; Franden, Mary Ann; Johnson, Christopher W; Chupka, Gina; Strathmann, Timothy J; Pienkos, Philip T; Beckham, Gregg T

    2014-08-19

    Lignin is an energy-dense, heterogeneous polymer comprised of phenylpropanoid monomers used by plants for structure, water transport, and defense, and it is the second most abundant biopolymer on Earth after cellulose. In production of fuels and chemicals from biomass, lignin is typically underused as a feedstock and burned for process heat because its inherent heterogeneity and recalcitrance make it difficult to selectively valorize. In nature, however, some organisms have evolved metabolic pathways that enable the utilization of lignin-derived aromatic molecules as carbon sources. Aromatic catabolism typically occurs via upper pathways that act as a "biological funnel" to convert heterogeneous substrates to central intermediates, such as protocatechuate or catechol. These intermediates undergo ring cleavage and are further converted via the ?-ketoadipate pathway to central carbon metabolism. Here, we use a natural aromatic-catabolizing organism, Pseudomonas putida KT2440, to demonstrate that these aromatic metabolic pathways can be used to convert both aromatic model compounds and heterogeneous, lignin-enriched streams derived from pilot-scale biomass pretreatment into medium chain-length polyhydroxyalkanoates (mcl-PHAs). mcl-PHAs were then isolated from the cells and demonstrated to be similar in physicochemical properties to conventional carbohydrate-derived mcl-PHAs, which have applications as bioplastics. In a further demonstration of their utility, mcl-PHAs were catalytically converted to both chemical precursors and fuel-range hydrocarbons. Overall, this work demonstrates that the use of aromatic catabolic pathways enables an approach to valorize lignin by overcoming its inherent heterogeneity to produce fuels, chemicals, and materials. PMID:25092344

  17. Ergonomical valorization of working spaces in multipurpose ships.

    PubMed

    Seif, Mehdi; Degiuli, Nastija; Mufti?, Osman

    2003-06-01

    In this work it is shown how anthropological data are among the most needed factors in ergonomical valorization of crew working spaces. Ship's working or living environment involves many unique human factors, which should be specially considered in our case as limitation of crew space. In this work we have chosen ships of different years of construction to prove this tendency. As a micro study, the work posture analysis using the pulling force experiment is performed in order to determine lumbar moment, intra-abdominal pressure as a measure of evaluating and comparing different crew work positions. As a macro-study, the "crew work posture analysis" was carried out by the use of the data collected from real cases. The most probable work postures in different spaces of a ship are classified and after some corrections of the work place the profile and its grade were determined. The "statistical analysis for real ship's spaces" is also performed, as well as another macro study, in order to show some real designed ship spaces from the point of view of the allocated volume. PMID:12974170

  18. Nuevos usos para el patrimonio arquitectónico industrial en Valladolid: completar equipamientos y generar valor

    Microsoft Academic Search

    Basilio Calderón Calderón

    2007-01-01

    El modelo de desarrollo urbanístico español de la segunda mitad del siglo XX provocó la pérdida de gran parte del patrimonio arquitectónico-industrial de las ciudades debido a la falta de conciencia de su valor patrimonial, la inadecuada legislación protectora, al alto valor estratégico de los emplazamientos y a la disponibilidad de otro tipo de contenedores socialmente mejor valorados –iglesias, palacios

  19. Organizational Citizenship Behavior: Social Valorization among Pupils and the Effect on Teachers' Judgments

    ERIC Educational Resources Information Center

    Esnard, Catherine; Jouffre, Stephane

    2008-01-01

    In this article, the concept of Organizational Citizenship Behavior (OCB) is transposed from a work context, in which it was developed, to secondary school. Two studies test the assumption of a social valorization of OCB declaration in a school context. In Study 1, 445 pupils (sixth-graders to ninth-graders) answered an OCB questionnaire,…

  20. Valorization of rapeseed meal. 3. Effects of glucosinolate content on food intake,

    E-print Network

    Paris-Sud XI, Université de

    Valorization of rapeseed meal. 3. Effects of glucosinolate content on food intake, weight gain Pessac, France. Summary. Seven groups of 10 growing rats each were fed a control diet or rapeseed diets. Introduction. The meals obtained from the first new rapeseed cultivars bred in France (Morice, 1974

  1. Lo sviluppo dell'impresa resource - based fra appropriazione e creazione di valore

    Microsoft Academic Search

    Arabella Mocciaro Li Destri; Giovanni Battista Dagnino

    2003-01-01

    Lo sviluppo dell'impresa resource - based fra appropriazione e creazione di valore (di Arabella Mocciaro Li Destri e Giovanni Battista Dagnino) - ABSTRACT: Various authors have brought forth the idea that the increase in context turbulence and the relentless change in today’s economic and competitive environments have rendered it essential for an effective strategy to combine both value appropriation and

  2. Study of the potential valorization of metal contaminated Salix via phytoextraction by combustion

    E-print Network

    Paris-Sud XI, Université de

    Study of the potential valorization of metal contaminated Salix via phytoextraction by combustion V: trace elements, phytoextraction, Salix, combustion, dredged sediment landfill site Abstract and biomass production. Two combustion assays were performed in a biomass boiler of 30 KW, the first one

  3. Tasas de ganancia, acumulación, producción y circulación: los conceptos básicos de la teoría clásica del valor

    Microsoft Academic Search

    Edith Alicia Klimovsky

    2006-01-01

    En los sistemas de industrias de productos simples y capital circulante sin recursos naturales, elaborados en el marco de la teoría clásica del valor, las tasas de ganancia, uniformes o no, pueden ser interpretadas en términos físicos, y los precios satisfacen tanto las condiciones de rentabilidad como las de circulación y son, por ende, precios de reproducción, cualquiera que sea

  4. EL VALOR DEL TIEMPO CON CONGESTIÓN: EL CASO DE LA RADIAL3 EN MADRID

    Microsoft Academic Search

    PEDRO CANTOS SÁNCHEZ; ÓSCAR ÁLVAREZ SAN-JAIME

    El presente trabajo muestra la importancia de valorar el tiempo que los au- tomovilistas viajan bajo congestión de manera separada al tiempo total del viaje. Nuestro trabajo obtiene que, para un viaje promedio en el corredor analizado, los usuarios valoran un minuto en congestión un 140% por en- cima del valor del tiempo en ausencia de restricciones de tráfico. Para

  5. El valor del tiempo con congestión: el caso de la radial-3

    Microsoft Academic Search

    Pedro Cantos Sánchez; Óscar Álvarez San-Jaime

    2009-01-01

    El presente trabajo muestra la importancia de valorar el tiempo que los automovilistas viajan bajo congestión de manera separada al tiempo total del viaje. Nuestro trabajo obtiene que, para un viaje promedio en el corredor analizado, los usuarios valoran un minuto en congestión un 140% por encima del valor del tiempo en ausencia de restricciones de tráfico. Para obtener este

  6. Gas to liquids technologies for natural gas reserves valorization: The Eni experience

    Microsoft Academic Search

    C. Perego; R. Bortolo; R. Zennaro

    2009-01-01

    In recent years, most oil companies have shown a renewed interest for the Fischer–Tropsch synthesis, as a result of the current carbon scenario and the stringent regulations on sulphur level in fuels. As a matter of fact, an overview of the oil and gas reserves underlines the necessity of gas valorization to liquid fuel, especially referring to stranded gas reserves.

  7. Quantidade Valor % apresentados Quantidade Valor Quantidade Valor Quantidade Valor Quantidade Valor Quantidade Valor

    Microsoft Academic Search

    Quantidade Valor

    2010-01-01

    Out 6 456.8 8 777.7 15.4 15.2 1 839.5 1 904.7 557.5 1 639.7 1 040.8 282.4 152.3 98.0 18.9 124.7 181.2 218.3 Nov 6 540.5 9 701.2 15.1 15.1 1 899.4 2 919.7 549.7 1 557.5 1 050.0 286.3 156.6 161.4 25.1 138.4 127.2 172.2 Dez 7 623.6 10 057.9 15.5 15.4 2 338.6 2 339.4 586.9 1 602.4

  8. NaF Documentation

    Cancer.gov

    The NaF documentation files are presented in Adobe Acrobat or Word files. PDF Generic Documentation for NaF PDF file Word Generic Documentation for NaF Word file Contact G. Craig Hill, Ph.D. for information. Email: hillgc@mail.nih.gov, Phone: 240-276-5913 Print

  9. Is phytoremediation without biomass valorization sustainable? - comparative LCA of landfilling vs. anaerobic co-digestion.

    PubMed

    Vigil, Miguel; Marey-Pérez, Manuel F; Martinez Huerta, Gemma; Álvarez Cabal, Valeriano

    2015-02-01

    This study examines the sustainability of phytoremediation for soils contaminated with heavy metals, especially the influence of management of the produced metal-enriched biomass on the environmental performance of the complete system. We examine a case study in Asturias (north of Spain), where the land was polluted with Pb by diffuse emissions from an adjacent steelmaking factory. A Phytoremediation scenario based on this case was assessed by performing a comparative life cycle assessment and by applying the multi-impact assessment method ReCiPe. Our Baseline scenario used the produced biomass as feedstock for an anaerobic digester that produces biogas, which is later upgraded cryogenically. The Baseline scenario was compared with two alternative scenarios: one considers depositing the produced biomass into landfill, and the other considers excavating the contaminated soil, disposing it in a landfill, and refilling the site with pristine soil. A sensitivity analysis was performed using different yields of biomass and biogas, and using different distances between site and biomass valorization/disposal center. Our results show that the impacts caused during agricultural activities and biomass valorization were compensated by the production of synthetic natural gas and the avoided impact of natural gas production. In addition, it was found that if the produced biomass was not valorized, the sustainability of phytoremediation is questionable. The distance between the site and the biomass processing center is not a major factor for determining the technology's sustainability, providing distances are less than 200-300 km. However, distance to landfill or to the source of pristine soil is a key factor when deciding to use phytoremediation or other ex-situ conventional remediation techniques. PMID:25461087

  10. Na +\\/H + antiporters

    Microsoft Academic Search

    Etana Padan; Miro Venturi; Yoram Gerchman; Nir Dover

    2001-01-01

    Na+\\/H+ antiporters are membrane proteins that play a major role in pH and Na+ homeostasis of cells throughout the biological kingdom, from bacteria to humans and higher plants. The emerging genomic sequence projects already have started to reveal that the Na+\\/H+ antiporters cluster in several families. Structure and function studies of a purified antiporter protein have as yet been conducted

  11. An "If This, Then that" Formulation of Decisions Related to Social Role Valorization as a Better Way of Interpreting It to People

    ERIC Educational Resources Information Center

    Wolfensberger, Wolf

    2011-01-01

    Social Role Valorization is interpreted as a high-order empirical social science theory that informs people about the relation between the social roles that people hold and what happens to them as a result, and how to valorize (improve or defend) the social roles of people at risk of social devaluation. Because Social Role Valorization is not a…

  12. Compositional insights and valorization pathways for carbonaceous material deposited during bio-oil thermal treatment.

    PubMed

    Ochoa, Aitor; Aramburu, Borja; Ibáñez, María; Valle, Beatriz; Bilbao, Javier; Gayubo, Ana G; Castaño, Pedro

    2014-09-01

    This work analyses the composition, morphology, and thermal behavior of the carbonaceous materials deposited during the thermal treatment of bio-oil (thermal pyrolytic lignin-TPL). The bio-oil was obtained by flash pyrolysis of lignocellulosic biomass (pine sawdust), and the TPLs were obtained in the 400-700?°C range. The TPLs were characterized by performing elemental analysis; (13)C?NMR, Raman, FTIR, and X-ray photoelectron spectroscopy; SEM; and temperature-programmed oxidation analyzed by differential thermogravimetry and differential scanning calorimetry. The results are compared to a commercial lignin (CL). The TPLs have lower oxygen and hydrogen contents and a greater aromaticity and structural order than the CL material. Based on these features, different valorization routes are proposed: the TPL obtained at 500?°C is suitable for use as a fuel, and the TPL obtained at 700?°C has a suitable morphology and composition for use as an adsorbent or catalyst support. PMID:25056736

  13. The environmental sustainability of anaerobic digestion as a biomass valorization technology.

    PubMed

    De Meester, Steven; Demeyer, Jens; Velghe, Filip; Peene, Andy; Van Langenhove, Herman; Dewulf, Jo

    2012-10-01

    This paper studies the environmental sustainability of anaerobic digestion from three perspectives. First, reference electricity is compared to electricity production from domestic organic waste and energy crop digestion. Second, different digester feed possibilities in an agricultural context are studied. Third, the influence of applying digestate as fertilizer is investigated. Results highlight that biomass is converted at a rational exergy (energy) efficiency ranging from 15.3% (22.6) to 33.3% (36.0). From a life cycle perspective, a saving of over 90% resources is achieved in most categories when comparing biobased electricity to conventional electricity. However, operation without heat valorization results in 32% loss of this performance while using organic waste (domestic and agricultural residues) as feedstock avoids land resources. The use of digestate as a fertilizer is beneficial from a resource perspective, but causes increased nitrogen and methane emissions, which can be reduced by 50%, making anaerobic digestion an environmentally competitive bioenergy technology. PMID:22864176

  14. Agricultural residue valorization using a hydrothermal process for second generation bioethanol and oligosaccharides production.

    PubMed

    Vargas, Fátima; Domínguez, Elena; Vila, Carlos; Rodríguez, Alejandro; Garrote, Gil

    2015-09-01

    In the present work, the hydrothermal valorization of an abundant agricultural residue has been studied in order to look for high added value applications by means of hydrothermal pretreatment followed by fed-batch simultaneous saccharification and fermentation, to obtain oligomers and sugars from autohydrolysis liquors and bioethanol from the solid phase. Non-isothermal autohydrolysis was applied to barley straw, leading to a solid phase with about a 90% of glucan and lignin and a liquid phase with up to 168gkg(-1) raw material valuable hemicellulose-derived compounds. The solid phase showed a high enzymatic susceptibility (up to 95%). It was employed in the optimization study of the fed-batch simultaneous saccharification and fermentation, carried out at high solids loading, led up to 52gethanol/L (6.5% v/v). PMID:26000836

  15. NA57 main results

    E-print Network

    G. E. Bruno; for the NA57 Collaboration

    2007-10-15

    The CERN NA57 experiment was designed to study the production of strange and multi-strange particles in heavy ion collisions at SPS energies; its physics programme is essentially completed. A review of the main results is presented.

  16. Preparation of sustainable photocatalytic materials through the valorization of industrial wastes.

    PubMed

    Sugrañez, Rafael; Cruz-Yusta, Manuel; Mármol, Isabel; Morales, Julián; Sánchez, Luis

    2013-12-01

    A new value-added material was developed from wastes to aim for appropriate waste management and sustainable development. This paper reports the valorization of industrial sandblasting operation wastes (SOWs) as new photocatalytic materials. This waste is composed of Fe2 O3 (60.7?%), SiO2 (29.1?%), and Al2 O3 (3.9?%) as the main components. The high presence of iron oxides was used to develop photocatalytic properties through their thermal transformation into ?-Fe2 O3 . The new product, SOW-T, exhibited a good behavior towards the photochemical degradation of organic dyes. The preparation of advanced photocatalytic materials that exhibit self-cleaning and depolluting properties was possible by the inclusion of SOW-T and TiO2 in a cement-based mortar. The synergy observed between both materials enhanced their photocatalytic action. To the best of our knowledge, this is the first report that describes the use of transformed wastes based on iron oxide for the photochemical oxidation of NOx gases. PMID:24106243

  17. A physicochemical-biotechnological approach for an integrated valorization of olive mill wastewater.

    PubMed

    Scoma, Alberto; Bertin, Lorenzo; Zanaroli, Giulio; Fraraccio, Serena; Fava, Fabio

    2011-11-01

    An integrated physicochemical-biotechnological approach for a multipurpose valorization of olive mill wastewaters was studied. More than 60% of the wastewater natural polyphenols were recovered through a solid phase extraction procedure, by employing Amberlite XAD16 resin as the adsorbent and ethanol as the biocompatible desorbing phase. Thereafter, the dephenolized effluent was fed to a mesophilic anaerobic acidogenic packed-bed biofilm reactor for the bioconversion of the organic leftover into volatile fatty acids (VFAs). A VFAs concentration of 19 gCODL(-1) was obtained, representing more than 70% of the COD occurring in the anaerobic effluent. The biotechnological process was assessed by means of bio-molecular analyses, which showed that the reactor packed bed was mostly colonized by bacteria of the Firmicutes phylogenetic group. The biorefinery scheme developed in this study allowed the obtainment of 1.59 g of polyphenols per liter of wastewater treated and 2.72 gCODL(-1) day(-1) of VFAs. PMID:21924896

  18. Catalytic lignin valorization process for the production of aromatic chemicals and hydrogen.

    PubMed

    Zakzeski, Joseph; Jongerius, Anna L; Bruijnincx, Pieter C A; Weckhuysen, Bert M

    2012-08-01

    With dwindling reserves of fossil feedstock as a resource for chemicals production, the fraction of chemicals and energy supplied by alternative, renewable resources, such as lignin, can be expected to increase in the foreseeable future. Here, we demonstrate a catalytic process to valorize lignin (exemplified with kraft, organosolv, and sugarcane bagasse lignin) using a mixture of cheap, bio-renewable ethanol and water as solvent. Ethanol/water mixtures readily solubilize lignin under moderate temperatures and pressures with little residual solids. The molecular weight of the dissolved lignins was shown to be reduced by gel permeation chromatography and quantitative HSQC NMR methods. The use of liquid-phase reforming of the solubilized lignin over a Pt/Al(2)O(3) catalyst at 498 K and 58 bar is introduced to yield up to 17 % combined yield of monomeric aromatic oxygenates such as guaiacol and substituted guaiacols generating hydrogen as a useful by-product. Reduction of the lignin dissolved in ethanol/water using a supported transition metal catalyst at 473 K and 30 bar hydrogen yields up to 6 % of cyclic hydrocarbons and aromatics. PMID:22740175

  19. Valorization of Brazilian vetiver (Vetiveria zizanioides (L.) Nash ex Small) oil.

    PubMed

    Martinez, Julian; Rosa, Paulo T V; Menut, Chantal; Leydet, Alain; Brat, Pierre; Pallet, Dominique; Meireles, M Angela A

    2004-10-20

    The valorization of extracts from Brazilian vetiver (Vetiveria zizanioides (L.) Nash ex Small) roots was studied. This study took into account the extraction method, the chemical composition of the extracts, their sensorial characteristics, and the possibility of chemical transformations of the product. The performed extraction methods were hydrodistillation and extraction with supercritical carbon dioxide. Some pretreatment methods were tested on the vetiver roots and evaluated in terms of extraction yield, process time, chemical composition, and sensorial properties. Supercritical carbon dioxide extraction resulted in high yield (3.2%) in significantly less time than the other methods. The chemical compositions of the extracts obtained by the different methods were also compared to those of commercial vetiver oils from other sources, showing that Brazilian samples had a greater acid amount. An extraction in basic medium from Brazilian vetiver oil was done to remove its main acid (zizanoic acid), which was chemically transformed into an alcohol (khusimol) of desirable sensorial properties. Sensory evaluation indicated that the Brazilian volatile oil without acid could be used in perfumery and the extract obtained with supercritical carbon dioxide could have application in food. PMID:15479026

  20. Thermal valorization of post-consumer film waste in a bubbling bed gasifier

    SciTech Connect

    Martínez-Lera, S., E-mail: susanamartinezlera@gmail.com; Torrico, J.; Pallarés, J.; Gil, A.

    2013-07-15

    Highlights: • Film waste from packaging is a common waste, a fraction of which is not recyclable. • Gasification can make use of the high energy value of the non-recyclable fraction. • This waste and two reference polymers were gasified in a bubbling bed reactor. • This experimental research proves technical feasibility of the process. • It also analyzes impact of composition and ER on the performance of the plant. - Abstract: The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m{sup 3} and cold gas efficiencies up to 60%.

  1. Thermal valorization of post-consumer film waste in a bubbling bed gasifier.

    PubMed

    Martínez-Lera, S; Torrico, J; Pallarés, J; Gil, A

    2013-07-01

    The use of plastic bags and film packaging is very frequent in manifold sectors and film waste is usually present in different sources of municipal and industrial wastes. A significant part of it is not suitable for mechanical recycling but could be safely transformed into a valuable gas by means of thermal valorization. In this research, the gasification of film wastes has been experimentally investigated through experiments in a fluidized bed reactor of two reference polymers, polyethylene and polypropylene, and actual post-consumer film waste. After a complete experimental characterization of the three materials, several gasification experiments have been performed to analyze the influence of the fuel and of equivalence ratio on gas production and composition, on tar generation and on efficiency. The experiments prove that film waste and analogue polymer derived wastes can be successfully gasified in a fluidized bed reactor, yielding a gas with a higher heating value in a range from 3.6 to 5.6 MJ/m3 and cold gas efficiencies up to 60%. PMID:23602300

  2. Valorization of rapeseed meal. 5. Effects of sinapine and other phenolic compounds on food intake and nutrient

    E-print Network

    Paris-Sud XI, Université de

    Valorization of rapeseed meal. 5. Effects of sinapine and other phenolic compounds on food intake of 10 growing rats each were fed ad libitum for 15 days one of six diets : diet A, rapeseed (3.80 g of sinapine/kg DM) ; diet B, ethanol/water-extracted rapeseed (0.48 g of sinapine) ; diet C, control diet

  3. Valorization of rapeseed meal. 2. Nutritive value of high or low-glucosinolate varieties and effect of dehulling

    E-print Network

    Paris-Sud XI, Université de

    Valorization of rapeseed meal. 2. Nutritive value of high or low-glucosinolate varieties and effect of either high glucosinolate (Jet Neuf) or low glucosinolate (Tan- dem) rapeseed meal. After a 3-day-dehulled. The Tandem rapeseed meal provided all the protein and Jet Neuf half the protein of the corresponding diets

  4. El tiempo es dinero: Cálculo del valor social del tiempo en Lima Metropolitana para usuarios de transporte urbano

    Microsoft Academic Search

    Denisse Calmet; Juan Miguel Capurro

    2011-01-01

    El objetivo de este trabajo es estimar el valor social del tiempo (VST) de los usuarios de transporte urbano en Lima Metropolitana. Con dicho fin, se presentan dos estimaciones del VST. En el primer caso, se utiliza información de la Encuesta Nacional de Hogares para aproximar el VST a partir del ingreso bruto mensual. En el segundo caso, utilizando información

  5. GESTIÓN EMPRESARIAL ORIENTADA AL VALOR DEL CLIENTE COMO FUENTE DE VENTAJA COMPETITIVA. PROPUESTA DE UN MODELO EXPLICATIVO

    Microsoft Academic Search

    LESLIER VALENZUELA; EDUARDO TORRES

    2008-01-01

    La globalización y el entorno altamente competitivo exigen a las empresas estar orientadas al mercado y gestionar su cartera de clientes como un activo estratégico clave para aumentar la rentabilidad del negocio y lograr una ventaja competitiva sostenible en el tiempo. El objetivo de este artículo es contribuir con una propuesta de modelo basado en el valor de la cartera

  6. EL VALOR DEL CONOCIMIENTO Y UN PLAN PARA USARLO EN INSTITUCIONES EDUCATIVAS DE LOS NIVELES INICIAL, BÁSICA, DIVERSIFICADA –PROFESIONAL

    Microsoft Academic Search

    Sira Vargas Rodríguez

    2010-01-01

    En este artículo se presenta el conocimiento como valor y se reflexiona sobre cómo podría usarse en cualquier institución educativa. Se considera que hay diferencias importantes en la escuela que le confieren singularidad y que impiden que se adopten estrategias creadas en las empresas para mejorar su calidad. Por ello, hablar de gerencia del conocimiento es reconocer que en la

  7. Energetic valorization of wood waste: estimation of the reduction in CO2 emissions.

    PubMed

    Vanneste, J; Van Gerven, T; Vander Putten, E; Van der Bruggen, B; Helsen, L

    2011-09-01

    This paper investigates the potential CO(2) emission reductions related to a partial switch from fossil fuel-based heat and electricity generation to renewable wood waste-based systems in Flanders. The results show that valorization in large-scale CHP (combined heat and power) systems and co-firing in coal plants have the largest CO(2) reduction per TJ wood waste. However, at current co-firing rates of 10%, the CO(2) reduction per GWh of electricity that can be achieved by co-firing in coal plants is five times lower than the CO(2) reduction per GWh of large-scale CHP. Moreover, analysis of the effect of government support for co-firing of wood waste in coal-fired power plants on the marginal costs of electricity generation plants reveals that the effect of the European Emission Trading Scheme (EU ETS) is effectively counterbalanced. This is due to the fact that biomass integrated gasification combined cycles (BIGCC) are not yet commercially available. An increase of the fraction of coal-based electricity in the total electricity generation from 8 to 10% at the expense of the fraction of gas-based electricity due to the government support for co-firing wood waste, would compensate entirely for the CO(2) reduction by substitution of coal by wood waste. This clearly illustrates the possibility of a 'rebound' effect on the CO(2) reduction due to government support for co-combustion of wood waste in an electricity generation system with large installed capacity of coal- and gas-based power plants, such as the Belgian one. PMID:21719072

  8. Valorization of agricultural waste into activated carbons and its adsorption characteristics for heavy metals

    NASA Astrophysics Data System (ADS)

    Koubaissy, Bachar; Toufaily, Joumana; Cheikh, Safaa; Hassan, Malak Sayed; Hamieh, Tayssir

    2014-03-01

    Activated carbon derived from pine cones waste was prepared by carbonization at 450°C, activated by different activating agents: ZnCl 2, H 2 SO 4 and NaOH, and then pyrolyzed at 600°C. Adsorption of Cr VI and other heavy metals (Mn II, Fe II, Cu II) on activated carbons was investigated to evaluate the adsorption properties. Special attention was paid to the effects of carbon surface functionalities that were analyzed by FT-IR and zeta potential study. Moreover, XRD study of activated carbon was also carried out. Results had shown that activated carbon by NaOH was the best adsorbent for removal of chromium VI from wastewater. The solid-solution interaction was determined by analyzing the adsorption isotherms at room temperature at different pH. When pH is above 4, the removal fraction of Cr (VI) ions decreased with the increase of pH. The removal fraction of Cr (VI) ions decreased below pH 4. The preferable removal of Cu (II) over Mn(II) and Fe (II) could be due to its lower affinity to solvent.Pseudo-second order equation provided the better correlation for the adsorption kinetics data. Equilibrium isotherms were determined by Fowler-Guggenheim model.

  9. Métodos directos e indirectos en la valoración económica de bienes ambientales, aplicación al valor de uso recreativo del Parque Natural de Somiedo

    Microsoft Academic Search

    L. GARCÍA DE LA FUENTE; A. COLINA VUELTA

    2004-01-01

    Una dificultad presente en la gestión de recursos medioambientales es la ausencia de mercados que asignen un valor económico a sus funciones. En este estudio, se ha aplicado un método directo de valoración (método dicotómico simple de valoración contingente) y otro indirecto (método individual del coste de viaje) para estimar el valor de uso recreativo que tiene un Espacio Natural

  10. El valor del uso recreativo del Parque Natural Sierra de MaríaLos Velez (Almería)

    Microsoft Academic Search

    Ma Encarnacion Castillo; Samir Sayadi; Felisa Cena

    2008-01-01

    RESUMEN: El objetivo de este artículo es estimar el valor de uso recreativo de un espacio protegido en el sur de España, el Parque Natural Sierra de María-Los Vélez en Almería, mediante el método del coste de viaje zonal. Los resultados obtenidos muestran un excedente del consumidor, entre 7,67-13,29 €\\/persona, según el escenario propuesto teniendo en cuenta el tiempo de

  11. Valorization of residual Empty Palm Fruit Bunch Fibers (EPFBF) by microfluidization: production of nanofibrillated cellulose and EPFBF nanopaper.

    PubMed

    Ferrer, Ana; Filpponen, Ilari; Rodríguez, Alejandro; Laine, Janne; Rojas, Orlando J

    2012-12-01

    Different cellulose pulps were produced from sulfur-free chemical treatments of Empty Palm Fruit Bunch Fibers (EPFBF), a by-product from palm oil processing. The pulps were microfluidized for deconstruction into nanofibrillated cellulose (NFC) and nanopaper was manufactured by using an overpressure device. The morphological and structural features of the obtained NFCs were characterized via atomic force and scanning electron microscopies. The physical properties as well as the interactions with water of sheets from three different pulps were compared with those of nanopaper obtained from the corresponding NFC. Distinctive chemical and morphological characteristics and ensuing nanopaper properties were generated by the EPFBF fibers. The NFC grades obtained compared favorably with associated materials typically produced from bleached wood fibers. Lower water absorption, higher tensile strengths (107-137 MPa) and elastic modulus (12-18 GPa) were measured, which opens the possibility for valorization of such widely available bioresource. PMID:23026341

  12. Challenges for Na-ion Negative Electrodes

    E-print Network

    Chevrier, V. L.

    Na-ion batteries have been proposed as candidates for replacing Li-ion batteries. In this paper we examine the viability of Na-ion negative electrode materials based on Na alloys or hard carbons in terms of volumetric ...

  13. Aithisg Bhliadhnail Coilltearachd na h-Alba

    E-print Network

    Aithisg Bhliadhnail Ùghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail 2007-2008 #12;Ùghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail 2007-08 1 | Ùghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail Leasachadh coimhearsnachd 11 Ruigsinneachd agus slàinte 14 Càileachd na h-àrainneachd 17 Bith-iomadachd 19 Mu

  14. NA-NET numerical analysis net

    Microsoft Academic Search

    Jack Dongarra; Bill Rosener

    1991-01-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host na-net.ornl.gov'' at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where

  15. Exergy analysis of the Chartherm process for energy valorization and material recuperation of chromated copper arsenate (CCA) treated wood waste.

    PubMed

    Bosmans, A; Auweele, M Vanden; Govaerts, J; Helsen, L

    2011-04-01

    The Chartherm process (Thermya, Bordeaux, France) is a thermochemical conversion process to treat chromated copper arsenate (CCA) impregnated wood waste. The process aims at maximum energy valorization and material recuperation by combining the principles of low-temperature slow pyrolysis and distillation in a smart way. The main objective of the exergy analysis presented in this paper is to find the critical points in the Chartherm process where it is necessary to apply some measures in order to reduce exergy consumption and to make energy use more economic and efficient. It is found that the process efficiency can be increased with 2.3-4.2% by using the heat lost by the reactor, implementing a combined heat and power (CHP) system, or recuperating the waste heat from the exhaust gases to preheat the product gas. Furthermore, a comparison between the exergetic performances of a 'chartherisation' reactor and an idealized gasification reactor shows that both reactors destroy about the same amount of exergy (i.e. 3500kWkg(wood)(-1)) during thermochemical conversion of CCA-treated wood. However, the Chartherm process possesses additional capabilities with respect to arsenic and tar treatment, as well as the extra benefit of recuperating materials. PMID:21195596

  16. Valorization of date palm (Phoenix dactylifera) fruit processing by-products and wastes using bioprocess technology - Review.

    PubMed

    Chandrasekaran, M; Bahkali, Ali H

    2013-04-01

    The date palm Phoenix dactylifera has played an important role in the day-to-day life of the people for the last 7000 years. Today worldwide production, utilization and industrialization of dates are continuously increasing since date fruits have earned great importance in human nutrition owing to their rich content of essential nutrients. Tons of date palm fruit wastes are discarded daily by the date processing industries leading to environmental problems. Wastes such as date pits represent an average of 10% of the date fruits. Thus, there is an urgent need to find suitable applications for this waste. In spite of several studies on date palm cultivation, their utilization and scope for utilizing date fruit in therapeutic applications, very few reviews are available and they are limited to the chemistry and pharmacology of the date fruits and phytochemical composition, nutritional significance and potential health benefits of date fruit consumption. In this context, in the present review the prospects of valorization of these date fruit processing by-products and wastes' employing fermentation and enzyme processing technologies towards total utilization of this valuable commodity for the production of biofuels, biopolymers, biosurfactants, organic acids, antibiotics, industrial enzymes and other possible industrial chemicals are discussed. PMID:23961227

  17. Sustainable valorization of plastic wastes for energy with environmental safety via High-Temperature Pyrolysis (HTP) and High-Temperature Steam Gasification (HTSG)

    Microsoft Academic Search

    E. Kantarelis; P. Donaj; W. Yang; A. Zabaniotou

    2009-01-01

    In the present study the energetic valorization of electric cable shredder residues (mixed plastics) has been investigated. Thermochemical conversion by means of High-Temperature Steam Gasification (HTSG) and High-Temperature Pyrolysis (HTP) was studied. The effects of temperature and reaction time – process parameters – were investigated. Comparison of the results showed that HTSG seems a more suitable process in terms of

  18. 'Cortar na investigao como queimar

    E-print Network

    Instituto de Sistemas e Robotica

    estar à espera de receber algo em troca' A conferência promovida pela Fundação Francisco Manuel dos problema que afeta vá- rios países, na Europa. O que é algo que me preocupa. Antes de mais, é preciso cultura, por exemplo, é a sociedade estar à espera de receber algo em troca. A ci- ência melhora a nossa

  19. Sodium iron hexacyanoferrate with high Na content as a Na-rich cathode material for Na-ion batteries

    DOE PAGESBeta

    Guo, Ya; Yu, Xiqian; You, Ya; Yin, Yaxia; Nam, Kyung -Wan

    2015-01-01

    Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large-scale grids. Increasing the Na content in cathode material is one of the effective ways to achieve high energy density. Prussian blue and its analogues (PBAs) are promising Na-rich cathode materials since they can theoretically store two Na ions per formula. However, increasing the Na content in PBAs cathode materials is a big challenge in the current. Here we show that sodium iron hexacyanoferrate with high Na content could be obtained by simply controlling the reducing agent and reaction atmospheremore »during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mA h g-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/de-intercalation mechanism is systematically studied by in situ Raman, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. The Na-rich sodium iron hexacyanoferrate could function as a plenteous Na reservoir and has great potential as a cathode material toward practical Na-ion batteries.« less

  20. Ionic regulation of Na absorption in proximal colon: cation inhibition of electroneutral Na absorption

    SciTech Connect

    Sellin, J.H.; De Soignie, R.

    1987-01-01

    Active Na absorption (J/sub net//sup NA/) in rabbit proximal colon in vitro is paradoxically stimulated as (Na) in the bathing media is lowered with constant osmolarity. J/sub m..-->..s//sup Na/ increases almost linearly from 0 to 50 mM (Na)/sub 0/ but then plateaus and actually decreases from 50 to 140 mM (Na)/sub 0/, consistent with inhibition of an active transport process. Both lithium and Na are equally effective inhibitors of J/sub net//sup Na/, whereas choline and mannitol do not block the high rate of J/sub net//sup Na/ observed in decreased (Na)/sub 0/. Either gluconate or proprionate replacement of Cl inhibits J/sub net//sup Na/. J/sub net//sup Na/ at lowered (Na)/sub 0/ is electrically silent and is accompanied by increased Cl absorption; it is inhibited by 10/sup -3/ M amiloride and 10/sup -3/ theophylline but not by 10/sup -4/ M bumetanide. Epinephrine is equally effective at stimulating Na absorption at 50 and 140 mM (Na). Na gradient experiments are consistent with a predominantly serosal effect of the decreased (Na)/sub 0/. These results suggest that 1) Na absorption in rabbit proximal colon in vitro is stimulated by decreased (Na); 2) the effect is cation specific, both Na and Li blocking the stimulatory effect; 3) the transport is mediated by Na-H exchange and is Cl dependent but 4) is under different regulatory mechanisms than the epinephrine-sensitive Na-Cl cotransport previously described in proximal colon. Under the appropriate conditions, proximal colon absorbs Na extremely efficiently. Na-H exchange in this epithelium is cation inhibitable, either directly or by a secondary regulatory process.

  1. Ionic regulation of Na absorption in proximal colon: cation inhibition of electroneutral Na absorption

    Microsoft Academic Search

    J. H. Sellin; R. De Soignie

    1987-01-01

    Active Na absorption (J\\/sub net\\/\\/sup NA\\/) in rabbit proximal colon in vitro is paradoxically stimulated as (Na) in the bathing media is lowered with constant osmolarity. J\\/sub m..-->..s\\/\\/sup Na\\/ increases almost linearly from 0 to 50 mM (Na)â but then plateaus and actually decreases from 50 to 140 mM (Na)â, consistent with inhibition of an active transport process. Both lithium

  2. Europlanet NA2 Science Networking

    NASA Astrophysics Data System (ADS)

    Harri, Ari-Matti; Szego, Karoly; Genzer, Maria; Schmidt, Walter; Krupp, Norbert; Lammer, Helmut; Kallio, Esa; Haukka, Harri

    2013-04-01

    Europlanet RI / NA2 Science Networking [1] focused on determining the major goals of current and future European planetary science, relating them to the Research Infrastructure that the Europlanet RI project [2] developed, and placing them in a more global context. NA2 also enhanced the ability of European planetary scientists to participate on the global scene with their own agenda-setting projects and ideas. The Networking Activity NA2 included five working groups, aimed at identifying key science issues and producing reference books on major science themes that will bridge the gap between the results of present and past missions and the scientific preparation of the future ones. Within the Europlanet RI project (2009-2012) the NA2 and NA2-WGs organized thematic workshops, an expert exchange program and training groups to improve the scientific impact of this Infrastructure. The principal tasks addressed by NA2 were: • Science activities in support to the optimal use of data from past and present space missions, involving the broad planetary science community beyond the "space club" • Science activities in support to the preparation of future planetary missions: Earth-based preparatory observations, laboratory studies, R&D on advanced instrumentation and exploration technologies for the future, theory and modeling etc. • Develop scientific activities, joint publications, dedicated meetings, tools and services, education activities, engaging the public and industries • Update science themes and addressing the two main scientific objectives • Prepare and support workshops of the International Space Science Institute (ISSI) in Bern and • Support Trans National Activities (TNAs), Joined Research Activities (JRAs) and the Integrated and Distributed Information Service (IDIS) of the Europlanet project These tasks were achieved by WG workshops organized by the NA2 working groups, by ISSI workshops and by an Expert Exchange Program. There were 17 official WG workshops and in addition there were numerous smaller NA2 WG meetings during the conferences (EPSC, EGU, etc.) and other events. The total number of NA2 meetings and workshops was 37. There were three NA2 supported ISSI workshops within the Europlanet project. The first ISSI workshop "Comparison of the plasma-spheres of Mars, Venus, and Titan" organized by K. Szego was held in December 2009. The second workshop "Quantifying the Martian Geochemical Reservoirs" by M. Toplis was held in April 2011. The third one, themed "Giant Planet Magnetodiscs and Aurorae" by N. Krupp, N. Achilleos and C. Arridge, was in November 2012. All three ISSI workshops were selected by the ISSI scientific committee to be organized within the frame of ISSI/Europlanet agreement and held in Bern. The main objective of the Expert Exchange Program was to support the activities of Europlanet RI with experts whenever needed. The programme provided funding for short visits (up to one week) of expert with the goal of improving infrastructure facilities and services offered to the scientific community by the Europlanet RI participant (contractor) laboratories or institutes. Between July 2009 and September 2012 26 applications were selected. Acknowledgement: Europlanet RI was funded by the European Commission under the 7th Framework Program, grant 228319 "Capacities Specific Programme" - Research Infrastructures Action. References: [1] http://www.europlanet-ri.eu/ [2] https://europlanet-scinet.fi/

  3. NA61/SHINE ion program

    E-print Network

    Maja Mackowiak for the NA61 Collaboration

    2010-09-06

    The Super Proton Synchrotron (SPS) at CERN covers one of the most interesting regions of the phase diagram (T - \\mu_{B}) of strongly interacting matter. The study of central Pb+Pb collisions by NA49 indicate that the threshold for deconfinement is reached already at the low SPS energies. Theoretical considerations predict a critical point of strongly interacting matter at energies accessible at the SPS. The NA61/SHINE experiment, a successor of the NA49 project, will study hadron production in p+p, p+A, h+A, and A+A reactions at various energies. The broad physics program includes the investigation of the properties of strongly interacting matter, as well as precision measurements of hadron spectra for the T2K neutrino experiment and for the Pierre Auger Observatory and KASCADE cosmic-ray projects. The main physics goals of the NA61/SHINE ion program are to study the properties of the onset of deconfinement at low SPS energies and to find signatures of the critical point of strongly interacting matter. To achieve these goals a broad range in the (T - \\mu_{B}) phase diagram will be covered by performing an energy (10A-158A GeV/c) and system size (p+p, B+C, Ar+Ca, Xe+La) scan. The first data for this 2-D scan were taken in 2009, i.e. p+p interactions at 20, 30, 40, 80, 158 GeV/c beam energy. This contribution will summarize physics arguments for the NA61/SHINE ion program, show the detector performance and present the current status of the experiment and plans for the next years.

  4. Na+ Tolerance and Na+ Transport in Higher Plants

    PubMed Central

    TESTER, MARK; DAVENPORT, ROMOLA

    2003-01-01

    Tolerance to high soil [Na+] involves processes in many different parts of the plant, and is manifested in a wide range of specializations at disparate levels of organization, such as gross morphology, membrane transport, biochemistry and gene transcription. Multiple adaptations to high [Na+] operate concurrently within a particular plant, and mechanisms of tolerance show large taxonomic variation. These mechanisms can occur in all cells within the plant, or can occur in specific cell types, reflecting adaptations at two major levels of organization: those that confer tolerance to individual cells, and those that contribute to tolerance not of cells per se, but of the whole plant. Salt?tolerant cells can contribute to salt tolerance of plants; but we suggest that equally important in a wide range of conditions are processes involving the management of Na+ movements within the plant. These require specific cell types in specific locations within the plant catalysing transport in a coordinated manner. For further understanding of whole plant tolerance, we require more knowledge of cell?specific transport processes and the consequences of manipulation of transporters and signalling elements in specific cell types. PMID:12646496

  5. NaCl Potentiates Human Fibrocyte Differentiation

    PubMed Central

    Cox, Nehemiah; Pilling, Darrell; Gomer, Richard H.

    2012-01-01

    Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can potentiate, in serum-free culture conditions, the differentiation of freshly-isolated human monocytes into fibroblast-like cells called fibrocytes. NaCl affects the monocytes directly during their adhesion. Potassium chloride and sodium nitrate also potentiate fibrocyte differentiation. The plasma protein Serum Amyloid P (SAP) inhibits fibrocyte differentiation. High levels of extracellular NaCl change the SAP Hill coefficient from 1.7 to 0.8, and cause a four-fold increase in the concentration of SAP needed to inhibit fibrocyte differentiation by 95%. Together, our data suggest that NaCl potentiates fibrocyte differentiation. NaCl-increased fibrocyte differentiation may thus contribute to NaCl-increased renal and cardiac fibrosis. PMID:23029177

  6. The MoNA Project

    NASA Astrophysics Data System (ADS)

    Vanwylen, P. J.; Bychowski, J. P.; Deyoung, P. A.; Peaslee, G. F.

    2002-10-01

    Many nuclear experiments involve the detection of neutrons after a reaction. This is especially true for radioactive nuclear beam experiments where the number of neutrons is often higher than in normal nuclear matter. Unlike charged particles, neutrons experience no Coulomb interaction, which makes their detection difficult. At the NSCL, this task has become even harder with the higher energies available from the coupled cyclotrons. The MoNA, or Modular Neutron Array, project is building a new neutron detector, which will achieve nearly 70% detection efficiency for neutron energies up to 250 MeV. The detector is comprised of 144 slats of scintillating plastic (200 x 10 x 10 cm) with photomultiplier tubes on each end to give position information of events. Hope College is one of nine undergraduate institutions involved in the MoNA collaboration. The construction process for Hope's sixteen neutron slats will be presented along with the results of testing showing that the slats give excellent position information. Light attenuation measurements generally exhibit the expected trends, but do not fit a standard exponential decay model precisely. A ray-tracing simulation of the slat geometry was created to investigate this behavior. Preliminary data from this program, reproducing some of the same unexpected results, will be shown.

  7. Evaluation of Fc?RIIIB-NA1/NA2 Polymorphism in Visceral Leishmaniasis

    PubMed Central

    Abasi, Mohammad; Lotfi, Pegah; Bazmani, Ahad; Matini, Mohamad; Hajilooi, Mehrdad

    2014-01-01

    Background: Several lines of evidence demonstrating that innate and adaptive immunity play important roles in the defense against visceral leishmaniasis (VL). A polymorphism within the Fc?RIIIB gene can lead to the expression of three variants of NA1, NA2, and the combined one (NA1/NA2) which alters affinity of IgG to its receptor. Objectives: The main aim of this study was to evaluate the Fc?RIIIB-NA1/NA2 polymorphism in the Fc?RIIIB gene of VL patients in comparison to healthy controls. Patients and Methods: In this cross-sectional study, three groups; 54 seropositive patients with clinical presentation of VL (group 1), 104 seropositive patients without clinical presentation (group 2), and 104 healthy controls (group 3) were evaluated with respect to the Fc?RIIIB-NA1/NA2 polymorphism using a PCR-SSP method. The titration of anti-leishmania antibodies was analyzed using an immunoflorescence technique. Results: Our results indicated that polymorphisms within the Fc?RIIIB gene (that lead to the expression of the NA1/NA2 isoforms) are significantly associated with VL. The results demonstrated that the genotype heterozygotic for Fc?RIIIB-NA1/NA2 expression was significantly increased in VL patients, group 1 when compared to groups 2 and 3. Conversely, there is a decrease in homozygous NA1 and NA2 genotypes in VL patients; however, the overall frequency of NA1 and NA2 alleles appear similar across the three cohorts examined. Conclusions: According to our results, it is likely that the increased frequency of the Fc?RIIIB-NA1/NA2 genotype is associated with impaired immune responses against VL and its subsequent clearance from the patient. PMID:24910789

  8. Simulation study of Na-majorite

    NASA Astrophysics Data System (ADS)

    Dymshits, A.; Vinograd, V.; Paulsen, N.; Winkler, B.; Perchuk, L.; Bobrov, A.

    2009-04-01

    Garnets, which are found as inclusions in diamonds, often have the excess of Na2O and SiO2 [Stachel, 2001]. Experimental studies suggest that Na is incorporated in pyrope-rich garnet via the coupled substitution Mg+Al=Na+Si [Bobrov et al., 2008]. This study is concerned with the determination of the structure and the thermodynamic properties of NaGrt (Na2MgSi5O12), which is assumed to be the end-member of pyrope-rich garnets with the excess of Na2O and SiO2. Static lattice energy calculations were performed with the program GULP [Gale & Rohl, 2003] using the force-field model [Vinograd et al., 2007] for 200 structures of Na2MgSi5O12 composition. These structures were prepared from Ia3-d pyrope Mg3Al2Si3O12 by replacing all octahedral Al atoms with Si and 2/3 of Mg atoms with Na. The distribution of Mg and Na was varied randomly. The static energies of these structures were cluster expanded using 8 pairwise effective cluster interactions (ECI). The ECIs were used to constrain Monte Carlo simulations within a 4×4×4 supercell (NNN exchangeable sites). The annealing experiments have shown that the lowest energy structure has the space group I4

  9. NA-NET numerical analysis net

    SciTech Connect

    Dongarra, J. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science Oak Ridge National Lab., TN (United States)); Rosener, B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science)

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host na-net.ornl.gov'' at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message send index'' to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user's perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  10. NA-NET numerical analysis net

    SciTech Connect

    Dongarra, J. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science]|[Oak Ridge National Lab., TN (United States); Rosener, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science

    1991-12-01

    This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host ``na-net.ornl.gov`` at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message ``send index`` to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user`s perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.

  11. Painful Na-channelopathies: an expanding universe.

    PubMed

    Waxman, Stephen G

    2013-07-01

    The universe of painful Na-channelopathies--human disorders caused by mutations in voltage-gated sodium channels--has recently expanded in three dimensions. We now know that mutations of sodium channels cause not only rare genetic 'model disorders' such as inherited erythromelalgia and channelopathy-associated insensitivity to pain but also common painful neuropathies. We have learned that mutations of NaV1.8, as well as mutations of NaV1.7, can cause painful Na-channelopathies. Moreover, recent studies combining atomic level structural models and pharmacogenomics suggest that the goal of genomically guided pain therapy may not be unrealistic. PMID:23664154

  12. Na+/Ca2+ exchange and Na+/K+-ATPase in the heart.

    PubMed

    Shattock, Michael J; Ottolia, Michela; Bers, Donald M; Blaustein, Mordecai P; Boguslavskyi, Andrii; Bossuyt, Julie; Bridge, John H B; Chen-Izu, Ye; Clancy, Colleen E; Edwards, Andrew; Goldhaber, Joshua; Kaplan, Jack; Lingrel, Jerry B; Pavlovic, Davor; Philipson, Kenneth; Sipido, Karin R; Xie, Zi-Jian

    2015-03-15

    This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation-contraction coupling and arrhythmias: Na(+) channel and Na(+) transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na(+)/Ca(2+) exchange (NCX) and Na(+)/K(+)-ATPase (NKA). While the relevance of Ca(2+) homeostasis in cardiac function has been extensively investigated, the role of Na(+) regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na(+) content have multiple effects on the heart by influencing intracellular Ca(2+) and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na(+) homeostasis. Among the proteins that accomplish this task are the Na(+)/Ca(2+) exchanger (NCX) and the Na(+)/K(+) pump (NKA). By transporting three Na(+) ions into the cytoplasm in exchange for one Ca(2+) moved out, NCX is one of the main Na(+) influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na(+) ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na(+) and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na(+) homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na(+)/Ca(2+) exchanger (NCX1) and Na(+)/K(+) pump and the controversies that still persist in the field. PMID:25772291

  13. NaHCO3 - A source of Na atoms for sudden sodium layers?

    Microsoft Academic Search

    Ulf von Zahn; Edmond Murad

    1990-01-01

    Consideration is given to the case of sudden sodium layers, reported in the lower E region of the ionosphere. It is suggested that dissociative electron attachment to NaHCO3, NaHCO3 + e yields Na + HCO3(-), can explain some of the observations, in particular at altitudes above 95 km. This process would produce Na efficiently only in the case where a

  14. Intracellular [Na +], Na + pathways, and fluid transport in cultured bovine corneal endothelial cells

    Microsoft Academic Search

    Kunyan Kuang; Yansui Li; Maimaiti Yiming; José M. Sánchez; Pavel Iserovich; E. J. Cragoe; Friedrich P. J. Diecke; Jorge Fischbarg

    2004-01-01

    The mechanism of fluid transport across corneal endothelium remains unclear. We examine here the relative contributions of cellular mechanisms of Na+ transport and the homeostasis of intracellular [Na+] in cultured bovine corneal endothelial cells, and the influence of ambient Na+ and HCO3?on the deturgescence of rabbit cornea. Bovine corneal endothelial cells plated on glass coverslips were incubated for 60 min

  15. Na3DyCl6

    PubMed Central

    Schurz, Christian M.; Meyer, Gerd; Schleid, Thomas

    2011-01-01

    Single crystals of the title compound, tris­odium hexa­chloridodysprosate, Na3DyCl6, were obtained as a by-product of synthesis using dysprosium(III) chloride and sodium chloride among others. The monoclinic structure with its typical ? angle close to 90° [90.823 (4)°] is isotypic with the mineral cryolite (Na3AlF6) and the high-temperature structure of the Na3 MCl6 series, with M = Eu–Lu, Y and Sc. The isolated, almost perfect [DyCl6]3? octa­hedra are inter­connected via two crystallographically different Na+ cations: while one Na+ resides on centres of symmetry (as well as Dy3+) and also builds almost perfect, isolated [NaCl6]5? octa­hedra, the other Na+ is surrounded by seven chloride anions forming a distorted [NaCl7]6? trigonal prism with just one cap as close secondary contact. PMID:21754259

  16. 7, 54135437, 2007 Global Na layer

    E-print Network

    Paris-Sud XI, Université de

    Discussions Satellite measurements of the global mesospheric sodium layer Z. Y. Fan1 , J. M. C. Plane2 , J Discussion EGU Abstract Optimal estimation theory is used to retrieve the absolute Na density profiles, have been analysed to yield the sea-5 sonal and latitudinal variation of the Na layer column abundance

  17. Regulation of Na+ fluxes in plants

    PubMed Central

    Maathuis, Frans J. M.; Ahmad, Izhar; Patishtan, Juan

    2014-01-01

    When exposed to salt, every plant takes up Na+ from the environment. Once in the symplast, Na+ is distributed within cells and between different tissues and organs. There it can help to lower the cellular water potential but also exert potentially toxic effects. Control of Na+ fluxes is therefore crucial and indeed, research shows that the divergence between salt tolerant and salt sensitive plants is not due to a variation in transporter types but rather originates in the control of uptake and internal Na+ fluxes. A number of regulatory mechanisms has been identified based on signaling of Ca2+, cyclic nucleotides, reactive oxygen species, hormones, or on transcriptional and post translational changes of gene and protein expression. This review will give an overview of intra- and intercellular movement of Na+ in plants and will summarize our current ideas of how these fluxes are controlled and regulated in the early stages of salt stress. PMID:25278946

  18. Secondary iron sulphates in AMD: a minerochemical analysis on jarosite supporting the valorization of its geoenvironmental contribution

    NASA Astrophysics Data System (ADS)

    Silva, Teresa; Figueiredo, Maria-Ondina

    2010-05-01

    Currently, iron sulphates formed in abandoned sulphide-ore mines have a very negative connotation within acid mine drainage (AMD) because in general these secondary hydroxilated and/or hydrated minerals concentrate a large span of toxic elements. However, this apparently penalizing feature may occasionally turn out to be a positive contribution, once sequestering such elements under the form of stable minerals significantly reduces their spread in soils and rivers, as occurs for jarosite in what concerns lead. The application of an exergetic analysis to resources consumption and sustainability assessment [1] provides a means of evaluating the degradation of mineral resources on Earth and a life cycle assessment (LCA) recently performed on some secondary iron sulphates has emphasized their exergetic contribution [2]. With the purpose of further exploring this positive aspect, and focusing on jarosite, a synopsis is presented on the structural features and geochemical tendencies of secondary iron sulphates liable of being exploited to promote their possible role. Jarosites (s.l.) - with general formula AB3(OH)6(SO4)2, where A is mainly K+, Na+, plus minor Ag+, Tl+, NH4+, Pb2+, Bi3+, and B is essentially Fe3+ (jarosite s.s.) or Al3+ (alunite) - have a trigonal crystal structure [3] and display Kagomé-type layers of corner-sharing B octahedra, [Fe/AlO2(OH)4], that give rise to unique magnetic properties [4]; the large cation A stays in pseudo-icosahedral coordination by 6 O-atoms from [SO4] tetrahedra and 6 hydroxyls shared with A octahedra [5]. A synopsis is presented on the crystal-chemistry and geochemical tendencies of jarosite and the geochemistry of sediments in the abandoned mine of S. Domingos (southern Portugal, Iberian Pyrite Belt of polymetallic sulphide ores), is briefly described to illustrate the positive environmental role of jarosite as energy-saver within the particularly aggressive environment of abandoned sulphide-ore mines. [1] B. de Meester et al. An improved calculation of the exergy of natural resources for exergetic life cycle assessment (ELCA). Environ. Sci. Technol. 40 (2006) 6844-6851. [2] M.O. Figueiredo, T.P. Silva & J. Mirão (2007) How does the uptake of lead along acid mine drainage processes affect the chemical exergy of jarosite in Exergetic Life Cycle Assessment (ELCA)? IEEES-3, 3rd Internat. Energy, Exergy & Environment Symp. (2007), CD-ROM, 4 pp., Edt. A.F. Miguel et al. (ISBN 978-989-95091-1-5). [3] B. Hendricks. The crystal structure of alunite and jarosite. Amer. Inst. Min. Metallurg. Engr. Technical Publ. 22 (1937) 773-784. [4] A.S. Wills et al. Magnetic properties of pure and diamagnetically doped jarosites: model kagomé antiferromagnets with variable coverage of the magnetic lattice. Phys. Rev B 61 (2000) 6156-6169. [5] S. Menchetti & C. Sabelli. Crystal chemistry of alunite series: crystal structure refinement of alunite and synthetic jarosite. Neues Jahrb. Miner. Monatsch. Heft 9 (1976) 406-417.

  19. Extracellular Na+ levels regulate formation and activity of the NaX/alpha1-Na+/K+-ATPase complex in neuronal cells

    PubMed Central

    Berret, Emmanuelle; Smith, Pascal Y.; Henry, Mélaine; Soulet, Denis; Hébert, Sébastien S.; Toth, Katalin; Mouginot, Didier; Drolet, Guy

    2014-01-01

    MnPO neurons play a critical role in hydromineral homeostasis regulation by acting as sensors of extracellular sodium concentration ([Na+]out). The mechanism underlying Na+-sensing involves Na+-flow through the NaX channel, directly regulated by the Na+/K+-ATPase ?1-isoform which controls Na+-influx by modulating channel permeability. Together, these two partners form a complex involved in the regulation of intracellular sodium ([Na+]in). Here we aim to determine whether environmental changes in Na+ could actively modulate the NaX/Na+/K+-ATPase complex activity. We investigated the complex activity using patch-clamp recordings from rat MnPO neurons and Neuro2a cells. When the rats were fed with a high-salt-diet, or the [Na+] in the culture medium was increased, the activity of the complex was up-regulated. In contrast, drop in environmental [Na+] decreased the activity of the complex. Interestingly under hypernatremic condition, the colocalization rate and protein level of both partners were up-regulated. Under hyponatremic condition, only NaX protein expression was increased and the level of NaX/Na+/K+-ATPase remained unaltered. This unbalance between NaX and Na+/K+-ATPase pump proportion would induce a bigger portion of Na+/K+-ATPase-control-free NaX channel. Thus, we suggest that hypernatremic environment increases NaX/Na+/K+-ATPase ?1-isoform activity by increasing the number of both partners and their colocalization rate, whereas hyponatremic environment down-regulates complex activity via a decrease in the relative number of NaX channels controlled by the pump. PMID:25538563

  20. NMR studies on Na+ transport in Synechococcus PCC 6311

    NASA Technical Reports Server (NTRS)

    Nitschmann, W. H.; Packer, L.

    1992-01-01

    The freshwater cyanobacterium Synechococcus PCC 6311 is able to adapt to grow after sudden exposure to salt (NaCl) stress. We have investigated the mechanism of Na+ transport in these cells during adaptation to high salinity. Na+ influx under dark aerobic conditions occurred independently of delta pH or delta psi across the cytoplasmic membrane, ATPase activity, and respiratory electron transport. These findings are consistent with the existence of Na+/monovalent anion cotransport or simultaneous Na+/H+ +anion/OH- exchange. Na+ influx was dependent on Cl-, Br-, NO3-, or NO2-. No Na+ uptake occurred after addition of NaI, NaHCO3, or Na2SO4. Na+ extrusion was absolutely dependent on delta pH and on an ATPase activity and/or on respiratory electron transport. This indicates that Na+ extrusion via Na+/H+ exchange is driven by primary H+ pumps in the cytoplasmic membrane. Cells grown for 4 days in 0.5 m NaCl medium, "salt-grown cells," differ from control cells by a lower maximum velocity of Na+ influx and by lower steady-state ratios of [Na+]in/[Na+]out. These results indicate that cells grown in high-salt medium increase their capacity to extrude Na+. During salt adaptation Na+ extrusion driven by respiratory electron transport increased from about 15 to 50%.

  1. Magnetic shielding of 23 Na nuclei in NaNO 3 and NaBrO 3 single crystals

    Microsoft Academic Search

    S. F. Sagnowski; Z. Sulek; M. Stachura; J. Ogar

    1982-01-01

    Single crystals of sodium nitrate, sodium chlorate and sodium bromate were investigated by continuous wave and Fourier transform pulse techniques. The sodium shielding tensors for studied compounds were found from the shift of the central line of23Na triplet, which was measured as a function of the crystal orientation. The shielding appears isotropic in NaNO3 and anisotropic in chlorate and bromate

  2. Catalysis of Na+ permeation in the bacterial sodium channel NaVAb

    PubMed Central

    Chakrabarti, Nilmadhab; Ing, Christopher; Payandeh, Jian; Zheng, Ning; Catterall, William A.; Pomès, Régis

    2013-01-01

    Determination of a high-resolution 3D structure of voltage-gated sodium channel NaVAb opens the way to elucidating the mechanism of ion conductance and selectivity. To examine permeation of Na+ through the selectivity filter of the channel, we performed large-scale molecular dynamics simulations of NaVAb in an explicit, hydrated lipid bilayer at 0 mV in 150 mM NaCl, for a total simulation time of 21.6 ?s. Although the cytoplasmic end of the pore is closed, reversible influx and efflux of Na+ through the selectivity filter occurred spontaneously during simulations, leading to equilibrium movement of Na+ between the extracellular medium and the central cavity of the channel. Analysis of Na+ dynamics reveals a knock-on mechanism of ion permeation characterized by alternating occupancy of the channel by 2 and 3 Na+ ions, with a computed rate of translocation of (6 ± 1) × 106 ions?s?1 that is consistent with expectations from electrophysiological studies. The binding of Na+ is intimately coupled to conformational isomerization of the four E177 side chains lining the extracellular end of the selectivity filter. The reciprocal coordination of variable numbers of Na+ ions and carboxylate groups leads to their condensation into ionic clusters of variable charge and spatial arrangement. Structural fluctuations of these ionic clusters result in a myriad of ion binding modes and foster a highly degenerate, liquid-like energy landscape propitious to Na+ diffusion. By stabilizing multiple ionic occupancy states while helping Na+ ions diffuse within the selectivity filter, the conformational flexibility of E177 side chains underpins the knock-on mechanism of Na+ permeation. PMID:23803856

  3. Catalysis of Na+ permeation in the bacterial sodium channel Na(V)Ab.

    PubMed

    Chakrabarti, Nilmadhab; Ing, Christopher; Payandeh, Jian; Zheng, Ning; Catterall, William A; Pomès, Régis

    2013-07-01

    Determination of a high-resolution 3D structure of voltage-gated sodium channel Na(V)Ab opens the way to elucidating the mechanism of ion conductance and selectivity. To examine permeation of Na(+) through the selectivity filter of the channel, we performed large-scale molecular dynamics simulations of Na(V)Ab in an explicit, hydrated lipid bilayer at 0 mV in 150 mM NaCl, for a total simulation time of 21.6 ?s. Although the cytoplasmic end of the pore is closed, reversible influx and efflux of Na(+) through the selectivity filter occurred spontaneously during simulations, leading to equilibrium movement of Na(+) between the extracellular medium and the central cavity of the channel. Analysis of Na(+) dynamics reveals a knock-on mechanism of ion permeation characterized by alternating occupancy of the channel by 2 and 3 Na(+) ions, with a computed rate of translocation of (6 ± 1) × 10(6) ions?s(-1) that is consistent with expectations from electrophysiological studies. The binding of Na(+) is intimately coupled to conformational isomerization of the four E177 side chains lining the extracellular end of the selectivity filter. The reciprocal coordination of variable numbers of Na(+) ions and carboxylate groups leads to their condensation into ionic clusters of variable charge and spatial arrangement. Structural fluctuations of these ionic clusters result in a myriad of ion binding modes and foster a highly degenerate, liquid-like energy landscape propitious to Na(+) diffusion. By stabilizing multiple ionic occupancy states while helping Na(+) ions diffuse within the selectivity filter, the conformational flexibility of E177 side chains underpins the knock-on mechanism of Na(+) permeation. PMID:23803856

  4. Removing antinutrients from rapeseed press-cake and their benevolent role in waste cooking oil-derived biodiesel: conjoining the valorization of two disparate industrial wastes.

    PubMed

    Das Purkayastha, Manashi; Das, Subrata; Manhar, Ajay Kumar; Deka, Dhanapati; Mandal, Manabendra; Mahanta, Charu Lata

    2013-11-13

    Valorization of oilseed processing wastes is thwarted due to the presence of several antinutritional factors such as phenolics, tannins, glucosinolates, allyl isothiocyanates, and phytates; moreover, literature reporting on their simultaneous extraction and subsequent practical application is scanty. Different solvent mixtures containing acetone or methanol pure or combined with water or an acid (hydrochloric, acetic, perchloric, trichloroacetic, phosphoric) were tested for their efficiency for extraction of these antinutritive compounds from rapeseed press-cake. Acidified extraction mixtures (nonaqueous) were found to be superior to the nonacidified ones. The characteristic differences in the efficacy of these wide varieties of solvents were studied by principal component analysis, on the basis of which the mixture 0.2% perchloric acid in methanol/acetone (1:1 v/v) was deemed as "the best" for detoxification of rapeseed meal. Despite its high reductive potential, hemolytic activity of the extract from this solvent mixture clearly indicated the toxicity of the above-mentioned compounds on mammalian erythrocytes. Because of the presence of a high amount of antinutritive antioxidants, the study was further extended to examine the influence of this solvent extract on the stability of waste cooking oil-derived biodiesel. Treatment with the extract harbored significant improvement (p < 0.05) in the induction periods and pronounced reduction in microbial load of stored biodiesel investigated herein. Thus, a suitable solvent system was devised for removing the major antinutrients from rapeseed press-cake, and the solvent extract can, thereafter, be used as an effective exogenous antioxidant for biodiesel. In other words, integrated valorization of two different industrial wastes was successfully achieved. PMID:24134775

  5. Hydrogen-fluorine exchange in NaBH4-NaBF4.

    PubMed

    Rude, L H; Filsø, U; D'Anna, V; Spyratou, A; Richter, B; Hino, S; Zavorotynska, O; Baricco, M; Sørby, M H; Hauback, B C; Hagemann, H; Besenbacher, F; Skibsted, J; Jensen, T R

    2013-11-01

    Hydrogen-fluorine exchange in the NaBH4-NaBF4 system is investigated using a range of experimental methods combined with DFT calculations and a possible mechanism for the reactions is proposed. Fluorine substitution is observed using in situ synchrotron radiation powder X-ray diffraction (SR-PXD) as a new Rock salt type compound with idealized composition NaBF2H2 in the temperature range T = 200 to 215 °C. Combined use of solid-state (19)F MAS NMR, FT-IR and DFT calculations supports the formation of a BF2H2(-) complex ion, reproducing the observation of a (19)F chemical shift at -144.2 ppm, which is different from that of NaBF4 at -159.2 ppm, along with the new absorption bands observed in the IR spectra. After further heating, the fluorine substituted compound becomes X-ray amorphous and decomposes to NaF at ~310 °C. This work shows that fluorine-substituted borohydrides tend to decompose to more stable compounds, e.g. NaF and BF3 or amorphous products such as closo-boranes, e.g. Na2B12H12. The NaBH4-NaBF4 composite decomposes at lower temperatures (300 °C) compared to NaBH4 (476 °C), as observed by thermogravimetric analysis. NaBH4-NaBF4 (1:0.5) preserves 30% of the hydrogen storage capacity after three hydrogen release and uptake cycles compared to 8% for NaBH4 as measured using Sievert's method under identical conditions, but more than 50% using prolonged hydrogen absorption time. The reversible hydrogen storage capacity tends to decrease possibly due to the formation of NaF and Na2B12H12. On the other hand, the additive sodium fluoride appears to facilitate hydrogen uptake, prevent foaming, phase segregation and loss of material from the sample container for samples of NaBH4-NaF. PMID:24071912

  6. Na+-mediated piezoprotection in Rhodotorula rubra.

    PubMed

    Aertsen, Abram; Masschalck, Barbara; Wuytack, Elke Y; Michiels, Chris W

    2003-12-01

    Sodium concentrations as low as 2 mM exerted a significant protective effect on the high-pressure inactivation (160-210 MPa) of Rhodotorula rubra at pH 6.5, but not on two other yeasts tested (Schizosaccharomyces pombe and Saccharomyces cerevisiae). A piezoprotective effect of similar magnitude was observed with Li+ (2 and 10 mM), and at elevated pH (8.0-9.0), but no effect was seen with K+, Ca2+, Mg2+, Mn2+, or NH4(+). Intracellular Na+ levels in cells exposed to low concentrations of Na+ or to pH 8.0-9.0 provided evidence for the involvement of a plasma membrane Na+/H+ antiporter and a correlation between intracellular Na+ levels and pressure resistance. The results support the hypothesis that moderate high pressure causes indirect cell death in R. rubra by inducing cytosolic acidification. PMID:14520537

  7. Nanosegregation in Na2C60

    SciTech Connect

    Klupp, G.; Kamaras, K.; Matus, P.; Kiss, L.F.; Kovats, E.; Pekker, S. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Nemes, N.M. [Instituto de Ciencia de Materiales de Madrid, Cantoblanco, 28049 Madrid (Spain); Quintavalle, D.; Janossy, A. [Department of Experimental Physics, Budapest University of Technology and Economics, Budafoki ut 8, Budapest, H-1111 (Hungary)

    2005-09-27

    There is continuous interest in the nature of alkali metal fullerides containing C{sub 60}{sup 4-} and C{sub 60}{sup 2-}, because these compounds are believed to be nonmagnetic Mott-Jahn-Teller insulators. This idea could be verified in the case of A4C60, but Na2C60 is more controversial. By comparing the results of infrared spectroscopy and X-ray diffraction, we found that Na2C60 is segregated into 3-10 nm large regions. The two main phases of the material are insulating C60 and metallic Na3C60. We found by neutron scattering that the diffusion of sodium ions becomes faster on heating. Above 470 K Na2C60 is homogeneous and we show IR spectroscopic evidence of a Jahn-Teller distorted C{sub 60}{sup 2-} anion.

  8. Determination of Na acceptor level in Na+ ion-implanted ZnO single crystal

    NASA Astrophysics Data System (ADS)

    Wang, Zheng; Liu, Huibin; He, Haiping; Huang, Jingyun; Chen, Lingxiang; Ye, Zhizhen

    2015-03-01

    Ion implantation was used to dope Na acceptor into ZnO single crystals. With three mixed implantation energies, uniform depth distribution of Na ion in the surface region (~300 nm) of ZnO bulk crystals is achieved. Via post-implantation annealing, a donor-acceptor pair recombination band is identified in the low-temperature photoluminescence spectra, from which the energy level of Na-related acceptor in single crystalline ZnO is estimated to be 300 meV. A p-n junction based on this ZnO-Na layer shows rectifying characteristics, confirming the p-type conductivity.

  9. Comparative aspects of Na+/K+ pump-mediated uncoupled Na+ efflux in red blood cells and kidney proteoliposomes.

    PubMed Central

    Martin, W H; Richards, D E; Marín, R; Jack-Hays, M; Hoffman, J F

    1994-01-01

    Ouabain-sensitive uncoupled Na+ efflux has been studied in human, pig, and rat red cells and in vesicles containing reconstituted kidney Na+/K+ pumps obtained from these same species. The red cells from the different species gave qualitatively similar results; the uncoupled Na+ efflux was 15-30% of the Na+/K+ exchange rate, and this flux was inhibited at 5 mM extracellular Na+ (Na+o). At higher levels of Na+o there was a monotonic increase in the Na+ efflux. As has previously been observed in human red cells, the uncoupled efflux from pig red cells consists of Na+ and anion cotransport, suggesting that anion cotransport may be a general characteristic of uncoupled Na+ efflux in red cells. The uncoupled Na+ efflux carried out by pig and rat kidney Na+/K+ pumps differs from the red cell activity in that it represents no more than 2-4% of the Na+/K+ exchange rate and that 5 mM Na+o does not inhibit this efflux. Furthermore, the efflux does not appear to be dependent on anion cotransport. Vesicles containing human kidney Na+/K+ pumps differ from vesicles derived from pig or rat kidneys in that the Na+ efflux is not inhibited or stimulated by Na+ present on the opposite side; it thus appears that the Na+,K(+)-ATPase in these vesicles may be incapable of Na+/Na+ exchange. These results indicate that the ligand and kinetic properties of the uncoupled Na+ efflux mode of red cells are markedly different from kidney-derived Na+/K+ pumps reconstituted into proteoliposomes. The basis for these differences may be inherent in the Na+/K+ pumps themselves or represent differences between the two types of preparations studied. PMID:7937910

  10. Jpi assignments in 25Na from 23Na(t, p)

    Microsoft Academic Search

    H. T. Fortune; R. Middleton; J. D. Garrett; R. M. Dreizler

    1978-01-01

    Results of the 23Na(t, p)25Na reaction establish Jpi = 3\\/2+ for the 90-keV state, confirm 3\\/2+ for the 2200-keV level, and establish positive parity (with J = 7\\/2 preferred) for the 2790-keV state.

  11. Na clusters on metal supported Ar layers

    NASA Astrophysics Data System (ADS)

    Faber, B.; Dinh, P. M.; Reinhard, P. G.; Suraud, E.

    2012-07-01

    We investigate from a theoretical perspective structure and dynamics of Na clusters on a surface built from Ar layers grown on a metal support. The system is modeled by a hierarchical quantum-mechanical/molecular-mechanical (QM/MM) approach treating the cluster electrons with time-dependent density-functional theory, the Ar atoms classically, and the metal support as a continuous dielectric medium. Caution has been taken to describe properly the dynamical polarizability of the Ar substrate. We study the effect of the Ar substrate and particularly of the metal support on the cluster structure and dynamics. The binding of Na6 and Na8 to the Ar surface is found to by very weak and the effect of the dielectric response of the metal (DRM) turns out to be negligible. The global properties of the optical response of the Na clusters are slightly changed by the Ar substrate and the DRM while the detailed spectral fragmentation depends sensitively on any change of the environment. The deposition dynamics of small Na clusters is crucially influenced by the mechanical hardness of the metal support while the DRM makes little effect. We also study the dependence on the number of Ar layers. For the first few layers (from two to four), the deposition dynamics changes dramatically with the number of layers. The results stabilize from six layers on upwards.

  12. The voltage-gated Na channel NaVBP has a role in motility, chemotaxis, and pH homeostasis

    E-print Network

    Clapham, David E.

    The voltage-gated Na channel NaVBP has a role in motility, chemotaxis, and pH homeostasisH homeostasis at high pH. Reduced motility of bacteria lacking functional NaVBP was reversed by restoration in response to chemoeffectors. Mutants lacking functional NaVBP were also defective in pH homeostasis

  13. Involvement of na in active uptake of pyruvate in mesophyll chloroplasts of some c(4) plants : na/pyruvate cotransport.

    PubMed

    Ohnishi, J; Flügge, U I; Heldt, H W; Kanai, R

    1990-11-01

    An artificial Na(+) gradient across the envelope (Na(+) jump) enhanced pyruvate uptake in the dark into mesophyll chloroplasts of a C(4) plant, Panicum miliaceum (NAD-malic enzyme type) (J Ohnishi, R Kanai [1987] FEBS Lett 219:347). In the present study, (22)Na(+) and pyruvate uptake were examined in mesophyll chloroplasts of several species of C(4) plants. Enhancement of pyruvate uptake by a Na(+) jump in the dark was also seen in mesophyll chloroplasts of Urochloa panicoides and Panicum maximum (phosphoenolpyruvate carboxykinase types) but not in Zea mays or Sorghum bicolor (NADP-malic enzyme types). In mesophyll chloroplasts of P. miliaceum and P. maximum, pyruvate in turn enhanced Na(+) uptake in the dark when added together with Na(+). When flux of endogenous Na(+) was measured in these mesophyll chloroplasts preincubated with (22)Na(+), pyruvate addition induced Na(+) influx, and the extent of the pyruvate-induced Na(+) influx positively correlated with that of pyruvate uptake. A Na(+)/H(+) exchange ionophore, monensin, nullified all the above mutual effects of Na(+) and pyruvate in mesophyll chloroplasts of P. miliaceum, while it accelerated Na(+) uptake and increased equilibrium level of chloroplast (22)Na(+). Measurements of initial uptake rates of pyruvate and Na(+) gave a stoichiometry close to 1:1. These results point to Na(+)/pyruvate cotransport into mesophyll chloroplasts of some C(4) plants. PMID:16667876

  14. Sodium-difluoro(oxalato)borate (NaDFOB): a new electrolyte salt for Na-ion batteries.

    PubMed

    Chen, Juner; Huang, Zhenguo; Wang, Caiyun; Porter, Spencer; Wang, Baofeng; Lie, Wilford; Liu, Hua Kun

    2015-06-01

    A new electrolyte salt, sodium-difluoro(oxalato)borate (NaDFOB), was synthesized and studied, which enables excellent reversible capacity and high rate capability when used in Na/Na0.44MnO2 half cells. NaDFOB has excellent compatibility with various common solvents used in Na-ion batteries, in strong contrast to the solvent dependent performances of NaClO4 and NaPF6. In addition, NaDFOB possesses good stability and generates no toxic or dangerous products when exposed to air and water. All these properties demonstrate that NaDFOB could be used to prepare high performance electrolytes for emerging Na-ion batteries. PMID:25987231

  15. Na+/K+-ATPase: Activity and inhibition

    NASA Astrophysics Data System (ADS)

    ?olovi?, M.; Krsti?, D.; Krinulovi?, K.; Momi?, T.; Savi?, J.; Vuja?i?, A.; Vasi?, V.

    2009-09-01

    The aim of the study was to give an overview of the mechanism of inhibition of Na+/K+-ATPase activity induced by some specific and non specific inhibitors. For this purpose, the effects of some ouabain like compounds (digoxin, gitoxin), noble metals complexes ([PtCl2DMSO2], [AuCl4]-, [PdCl4]2-, [PdCl(dien)]+, [PdCl(Me4dien)]+), transition metal ions (Cu2+, Zn2+, Fe2+, Co2+), and heavy metal ions (Hg2+, Pb2+, Cd2+) on the activity of Na+/K+-ATPase from rat synaptic plasma membranes (SPM), porcine cerebral cortex and human erythrocytes were discussed.

  16. Semisynthesis of NaK; a Na+ and K+ conducting ion channel

    PubMed Central

    Linn, Kellie M.; Derebe, Mehebaw G.; Jiang, Youxing; Valiyaveetil, Francis I.

    2010-01-01

    In this contribution, we describe the semisynthesis of NaK, a bacterial non-selective cation channel. In the semisynthesis, the NaK polypeptide is assembled from a recombinantly expressed thioester peptide and a chemically synthesized peptide using the native chemical ligation reaction. We describe a temporary tagging strategy for the purification of the hydrophobic synthetic peptide and demonstrate the efficient ligation of the synthetic peptide with the recombinant peptide thioester to form the semisynthetic NaK polypeptide. Following assembly, the NaK polypeptide is folded in vitro to the native state using lipid vesicles. Functional characterization of the folded semisynthetic NaK channels indicates that it is functionally similar to the wild type protein. We used semisynthesis to substitute aspartate 66 in the selectivity filter region of the NaK channel with the unnatural amino acids, homoserine and cysteine sulfonic acid. Functional analysis of these mutants suggests that the presence of a negatively charged residue in the vicinity of the ion binding sites is necessary for optimal flux of ions through the NaK channel. PMID:20415433

  17. Na+ inhibits the epithelial Na+ channel by binding to a site in an extracellular acidic cleft.

    PubMed

    Kashlan, Ossama B; Blobner, Brandon M; Zuzek, Zachary; Tolino, Michael; Kleyman, Thomas R

    2015-01-01

    The epithelial Na(+) channel (ENaC) has a key role in the regulation of extracellular fluid volume and blood pressure. ENaC belongs to a family of ion channels that sense the external environment. These channels have large extracellular regions that are thought to interact with environmental cues, such as Na(+), Cl(-), protons, proteases, and shear stress, which modulate gating behavior. We sought to determine the molecular mechanism by which ENaC senses high external Na(+) concentrations, resulting in an inhibition of channel activity. Both our structural model of an ENaC ? subunit and the resolved structure of an acid-sensing ion channel (ASIC1) have conserved acidic pockets in the periphery of the extracellular region of the channel. We hypothesized that these acidic pockets host inhibitory allosteric Na(+) binding sites. Through site-directed mutagenesis targeting the acidic pocket, we modified the inhibitory response to external Na(+). Mutations at selected sites altered the cation inhibitory preference to favor Li(+) or K(+) rather than Na(+). Channel activity was reduced in response to restraining movement within this region by cross-linking structures across the acidic pocket. Our results suggest that residues within the acidic pocket form an allosteric effector binding site for Na(+). Our study supports the hypothesis that an acidic cleft is a key ligand binding locus for ENaC and perhaps other members of the ENaC/degenerin family. PMID:25389295

  18. Organization Through participation in the Na-

    E-print Network

    Robeson, Scott M.

    Organization Through participation in the Na- tional Council on U.S.-Arab Re- lations' Model Arab League (MAL)programstudents learn about the politics and history of the Arab world, and the arts welcome universitiesand high schools from across the United States to participate. MODEL ARAB LEAGUE CALL

  19. MoNA—The Modular Neutron Array

    Microsoft Academic Search

    B. Luther; T. Baumann; M. Thoennessen; J. Brown; P. Deyoung; J. Finck; J. Hinnefeld; R. Howes; K. Kemper; P. Pancella; G. Peaslee; W. Rogers; S. Tabor

    2003-01-01

    The Modular Neutron Array (MoNA), a highly efficient time-of-flight neutron detector, is being constructed for use at the National Superconducting Cyclotron Laboratory. The modular design of the detector provides significant flexibility and allows the bulk of the assembly and testing to be done by undergraduates at nine of the schools participating in the project.

  20. master's degree NaNotechNology

    E-print Network

    Twente, Universiteit

    master's degree NaNotechNology When choosing a Master's programme, it is wise to look one step topical, incorporating the latest developments in applied physics, nanotechnology, chemical engineering projects will be carried out at the MESA+ institute for nanotechnology, or the MIRA institute

  1. Laser trapping of {sup 21}Na atoms

    SciTech Connect

    Lu, Zheng-Tian

    1994-09-01

    This thesis describes an experiment in which about four thousand radioactive {sup 21}Na (t{sub l/2} = 22 sec) atoms were trapped in a magneto-optical trap with laser beams. Trapped {sup 21}Na atoms can be used as a beta source in a precision measurement of the beta-asymmetry parameter of the decay of {sup 21}Na {yields} {sup 21}Ne + {Beta}{sup +} + v{sub e}, which is a promising way to search for an anomalous right-handed current coupling in charged weak interactions. Although the number o trapped atoms that we have achieved is still about two orders of magnitude lower than what is needed to conduct a measurement of the beta-asymmetry parameter at 1% of precision level, the result of this experiment proved the feasibility of trapping short-lived radioactive atoms. In this experiment, {sup 21}Na atoms were produced by bombarding {sup 24}Mg with protons of 25 MeV at the 88 in. Cyclotron of Lawrence Berkeley Laboratory. A few recently developed techniques of laser manipulation of neutral atoms were applied in this experiment. The {sup 21}Na atoms emerging from a heated oven were first transversely cooled. As a result, the on-axis atomic beam intensity was increased by a factor of 16. The atoms in the beam were then slowed down from thermal speed by applying Zeeman-tuned slowing technique, and subsequently loaded into a magneto-optical trap at the end of the slowing path. The last two chapters of this thesis present two studies on the magneto-optical trap of sodium atoms. In particular, the mechanisms of magneto-optical traps at various laser frequencies and the collisional loss mechanisms of these traps were examined.

  2. Thermodynamics of Na 2 O-SiO 2 melts

    Microsoft Academic Search

    A. I. Zaitsev; N. E. Shelkova; B. M. Mogutnov

    2000-01-01

    The thermodynamic properties of Na2O-SiO2 solid (942-1285 K) and liquid (1103-1719 K, 19.5-61.8 mol % Na2O) silicates were studied by Knudsen cell mass spectrometry. To determine the activities of the constituent oxides, these\\u000a were reduced to volatile suboxides directly in effusion cells. Mass spectra of the saturated vapor over Na2O-SiO2 showed the presence of the Na+, Na2O+, NaO+, O\\u000a 2

  3. Permissive effect of thyroid hormones on induction of rat colonic Na + transport by aldosterone is not localised at the level of Na + channel transcription

    Microsoft Academic Search

    Libor Mrnka; Ji??? Pácha

    2000-01-01

    The interrelationship between thyroid hormones and aldosterone has been examined in the regulation of rat colonic amiloride-sensitive Na+ transport which translocates Na+ through apical amiloride-sensitive Na+ channels and basolateral Na+,K+-ATPase. Electrogenic Na+ transport was measured in an Ussing chamber by the short-circuit current and identified by Na+ channel blocker amiloride. Na+-pumping activity of the basolateral Na+,K+-ATPase was investigated in nystatin-treated

  4. [Gating properties of cardiac Na channels: from the macroscopic Na current viewpoint].

    PubMed

    Sada, H; Ban, T; Ebina, Y

    1993-08-01

    The sodium channel plays essential roles in the initiation and propagation of action potentials (APs) in excitable tissues including the heart, nerves, and muscles. Na channels in these tissues undergo so-called activation and then inactivation upon step-depolarizations of the cell membrane. Hodgkin and Huxley, early in the 1950s, proposed a mathematical model to describe such events, which was based on voltage-clamp (V-C) data on axonal membranes. However, for the next 30 years or so since the pioneering work of the above workers, electrophysiological studies of the Na channel kinetics in the heart had relied exclusively on AP data (Vmax) as an indirect measure of the Na current instead of V-C data due to difficulty in determining V-C from the complex geometry of cardiac tissues. However, recent development of an isolation procedure for preparing single heart cells and the use of single patch-pipettes for high resolution V-C experiments on these cells have made direct recording of Na channel currents also possible in the heart. Voltage-clamp studies carried out for the last decade have provided several lines of evidence supporting the view that the Na channel properties in the heart of any animal species are somehow more complex than in the axonal membrane and hence showing that Hodgkin-Huxley model can not be directly applied to describe the Na channel behavior in the former type of tissues. Here, we review recent results from V-C studies on Na channel properties with special reference to the macroscopic Na current in cardiac tissues. PMID:8396556

  5. Studies of Inelastic Collisions of NaK and NaCs Molecules with Atomic Perturbers

    NASA Astrophysics Data System (ADS)

    Jones, Joshua A.

    We have investigated collisions of NaK molecules in the first excited state [2(A)1Sigma+], with Ar and He collision partners using laser-induced fluorescence spectroscopy (LIF) and polarization-labeling (PL) spectroscopy in a two-step excitation scheme. Additionally, we have investigated collisions of NaCs molecules in the first excited state [2(A)1Sigma +] with Ar and He perturbers using the LIF technique. We use a pump-probe, two-step excitation process. The pump laser prepares the molecule in a particular ro-vibrational (v, J) level in the A state. The probe laser frequency is scanned over transitions to the 31? in NaK or to the 53? in NaCs. In addition to observing strong direct lines, we also see weak collisional satellite lines that arise from collisions in the intermediate state that take the molecule from the prepared level (v, J) to level (v, J + Delta J). The ratio of the intensity of the collisional line to the intensity of the direct line in LIF and PL yield information about population and orientation transfer. Our results show a propensity for DeltaJ=even collisions of NaK with Ar and an even stronger propensity for collisions with He. Collisions of NaCs with Ar do not show any such J=even propensity. Preliminary investigations of collisions of NaCs with He seem to indicate a slight J=even propensity. In addition, we observe that rotationally inelastic collisions of excited NaK molecules with potassium atoms destroy almost all of the orientation, while collisions with argon destroy about one third to two thirds and collisions with helium destroy only about zero to one third of the initial orientation.

  6. Intracellular Na+ regulation of Na+ pump sites in cultured vascular smooth muscle cells

    SciTech Connect

    Allen, J.C.; Navran, S.S.; Seidel, C.L.; Dennison, D.K.; Amann, J.M.; Jemelka, S.K.

    1989-04-01

    Enzymatically dispersed cells from canine saphenous vein and femoral artery were grown in fetal calf serum and studied at day 0 (freshly dispersed) through confluence in primary culture. Intracellular Na levels (Nai), but not intracellular K (Ki), were increased after 24 h in culture and then decreased to a steady state by 4 days. Na+ pump site number (( /sup 3/H) ouabain binding) increased through day 3 and remained elevated. Nai was still elevated at 2 days when the Na+ pump site number began to increase. Total pump turnover (maximum ouabain-inhibited /sup 86/Rb uptake) reflected the increase in Na+ pump site number. These key events precede the observed increases in both protein production and cellular proliferation. If the same cells are maintained in defined medium, without fetal calf serum, Nai, Ki, and the number of (/sup 3/H)ouabain binding sites do not change with time. These data are consistent with the suggestion that the initial mitogenic response of vascular smooth muscle cells to fetal calf serum involves an increased Na+ influx, and a Nai accumulation, caused by low Na+ pump density. The synthesis of new pump sites effects a decrease in the accumulated Nai, which may be related to cell proliferation.

  7. Na/beta-alumina/NaAlCl4, Cl2/C circulating cell

    NASA Technical Reports Server (NTRS)

    Cherng, Jing-Yih; Bennion, Douglas N.

    1987-01-01

    A study was made of a high specific energy battery based on a sodium negative electrode and a chlorine positive electrode with molten AlCl3-NaCl electrolyte and a solid beta alumina separator. The basic performance of a Na beta-alumina NaAlCl4, Cl2/C circulating cell at 200 C was demonstrated. This cell can be started at 150 C. The use of melting sodium chloroaluminate electrolyte overcomes some of the material problems associated with the high working temperatures of present molten salt systems, such as Na/S and LiAl/FeS, and retains the advantages of high energy density and relatively efficient electrode processes. Preliminary investigations were conducted on a sodium-chlorine static cell, material compability, electrode design, wetting, and theoretical calculations to assure a better chance of success before assembling a Na/Cl2 circulating cell. Mathematical models provide a theoretical explanation for the performance of the NaCl2 battery. The results of mathematical models match the experimental results very well. According to the result of the mathematical modeling, an output at 180 mA/sq cm and 3.2 V can be obtained with optimized cell design.

  8. An enhancement to the NA4 gear vibration diagnostic parameter

    NASA Technical Reports Server (NTRS)

    Decker, Harry J.; Handschuh, Robert F.; Zakrajsek, James J.

    1994-01-01

    A new vibration diagnostic parameter for health monitoring of gears, NA4*, is proposed and tested. A recently developed gear vibration diagnostic parameter NA4 outperformed other fault detection methods at indicating the start and initial progression of damage. However, in some cases, as the damage progressed, the sensitivity of the NA4 and FM4 parameters tended to decrease and no longer indicated damage. A new parameter, NA4* was developed by enhancing NA4 to improve the trending of the parameter. This allows for the indication of damage both at initiation and also as the damage progresses. The NA4* parameter was verified and compared to the NA4 and FM4 parameters using experimental data from single mesh spur and spiral bevel gear fatigue rigs. The primary failure mode for the test cases was naturally occurring tooth surface pitting. The NA4* parameter is shown to be a more robust indicator of damage.

  9. Rechargeable Na/Na0.44MnO2 cells with ionic liquid electrolytes containing various sodium solutes

    NASA Astrophysics Data System (ADS)

    Wang, Chueh-Han; Yeh, Yu-Wen; Wongittharom, Nithinai; Wang, Yi-Chen; Tseng, Chung-Jen; Lee, Sheng-Wei; Chang, Wen-Sheng; Chang, Jeng-Kuei

    2015-01-01

    Orthorhombic Na0.44MnO2 with wide structural tunnels for sodium ion transport is synthesized. Butylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (BMP-TFSI) ionic liquid (IL) with various Na solutes, namely NaBF4, NaClO4, NaTFSI, and NaPF6, is used as an electrolyte for rechargeable Na/Na0.44MnO2 cells. The cell with NaClO4-incorporated IL electrolyte exhibits superior charge-discharge performance due to it having the lowest solid-electrolyte-interface resistance and charge transfer resistance at both the Na and Na0.44MnO2 electrodes. The IL electrolyte shows high thermal stability and is suitable for use at an elevated temperature. At 75 °C, the measured capacity of Na0.44MnO2 in the IL electrolyte with NaClO4 is as high as 115 mAh g-1 (at 0.05 C), which is close to the theoretical value (121 mAh g-1). Moreover, 85% of this capacity can be retained when the charge-discharge rate is increased to 1 C. These properties are superior to those of a conventional organic electrolyte.

  10. Bumetanide inhibition of NaCl transport by Necturus gallbladder

    Microsoft Academic Search

    Mikael Larson; Kenneth R. Spring

    1983-01-01

    Summary Salt transport by theNecturus gallbladder epithelium is the result of the coupled entry of NaCl into the cells across the apical membrane and the active transport of Na out of the cells across the basolateral membrane. The NaCl entry step was studied by measuring the rate of cell volume increase accompanying ouabain inhibition of the Na-K-ATPase in the basolateral

  11. Immunohistochemical localization of Na + -dependent glucose transporter in rat jejunum

    Microsoft Academic Search

    Kuniaki Takata; Toshiko Kasahara; Michihiro Kasahara; Osamu Ezaki; Hiroshi Hirano

    1992-01-01

    Glucose is actively absorbed via a Na+-dependent active glucose transporter (Na-GT) in the small intestine. We raised a polyclonal antibody against the peptide corresponding to amino acids 564–575 of rabbit intestinal Na-GT, and localized it immunohistochemically in the rat jejunum. By means of immunofluorescence staining, Na-GT was located at the brush border of the absorptive epithelial cells of the intestinal

  12. {beta} decay of {sup 32}Na

    SciTech Connect

    Mattoon, C. M. [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States); Sarazin, F. [Department of Physics, Colorado School of Mines, Golden, Colorado 80401 (United States); TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Hackman, G.; Ball, G. C.; Chakrawarthy, R. S.; Scraggs, H. C.; Smith, M. B. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Cunningham, E. S.; Walker, P. M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Austin, R. A. E. [Department of Physics and Astronomy, Saint Mary's University, Halifax, Nova Scotia, Canada B3H 3C3 (Canada); Finlay, P.; Grinyer, G. F.; Hyland, B.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E. [Department of Physics, University of Guelph, Guelph, Ontario, Canada N1G 2W1 (Canada); Garrett, P. E. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1 (Canada); Koopmans, K. A.; Waddington, J. C.; Washbrook, B. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4K1 (Canada)] (and others)

    2007-01-15

    The {beta}-decay of {sup 32}Na has been studied using {beta}-{gamma} coincidences. New transitions and levels are tentatively placed in the level scheme of {sup 32}Mg from an analysis of {gamma}-{gamma} and {beta}-{gamma}-{gamma} coincidences. The observation of the indirect feeding of the 2321 keV state in {sup 32}Mg removes some restrictions previously placed on the spin assignment for this state. No evidence of a state at 2117 keV in {sup 32}Mg is found. Previously unobserved weak transitions up to 5.4 MeV were recorded but could not be placed in the decay scheme of {sup 32}Na.

  13. Na+-driven bacterial flagellar motors.

    PubMed

    Imae, Y; Atsumi, T

    1989-12-01

    Bacterial flagellar motors are the reversible rotary engine which propels the cell by rotating a helical flagellar filament as a screw propeller. The motors are embedded in the cytoplasmic membrane, and the energy for rotation is supplied by the electrochemical potential of specific ions across the membrane. Thus, the analysis of motor rotation at the molecular level is linked to an understanding of how the living system converts chemical energy into mechanical work. Based on the coupling ions, the motors are divided into two types; one is the H+-driven type found in neutrophiles such as Bacillus subtilis and Escherichia coli and the other is the Na+-driven type found in alkalophilic Bacillus and marine Vibrio. In this review, we summarize the current status of research on the rotation mechanism of the Na+-driven flagellar motors, which introduces several new aspects in the analysis. PMID:2687262

  14. The complex lightcurve of 1992 NA

    NASA Technical Reports Server (NTRS)

    Wisniewski, Wieslaw Z.; Harris, A. W.

    1994-01-01

    Amor asteroid 1992 NA was monitored during three nights at a large phase angle of -65 deg. The lightcurves obtained did not reveal a repeatable curve with two maxima and two minima. However, some features suggested a periodicity with three maxima and three minima. A satisfactory composite lightcurve of this form was obtained by means of an 'eyeball' fit and by Fourier analysis. Individual and composite lightcurves are presented. The observed colors are consistent with the C class.

  15. The temperature dependence of the cross section for the energy pooling process Na(3P)+Na(3P) to Na(4D)+Na(3S)

    NASA Astrophysics Data System (ADS)

    Horvatic, V.; Movre, M.; Vadla, C.

    1999-10-01

    We report the measurements of the temperature dependence of the cross section ?4D for the energy pooling process Na(3P)+Na(3P) to Na(4D)+Na(3S). The latest two, as yet undisputed, results for ?4D obtained by different authors at T = 597 K and T = 483 K suggest that this cross section decreases with increasing T, which contradicts the theory and other experiments on similar processes. To resolve this controversy and to examine the temperature trend of the cross section, we have measured the ?4D in the temperature range 567-705 K, covering the high-temperature region that has not yet been investigated experimentally. To determine ?4D we have excited sodium atoms in the quasistatic wing of the D1 line using a cw dye laser and measured the fluorescence intensity for the 4D to 3P3/2 transition, relative to the intensity of the optically thin quasistatic wing of the D2 line. The spatial distribution of the number density of the sodium atoms in the 3P3/2 state and the sodium ground-state number density were measured too. The method used for the determination of the cross section is advantageous since it entirely circumvents the need to account for the radiation trapping of 3P level radiation, which was substantial under experimental conditions of the ground-state densities being 1014-1016 cm-3. The measurements of the cross section ?4D in the investigated temperature range have shown that it increases as ~exp(-? E/kT). From the experiment we obtained ? E = (608±95) cm-1, which is in excellent agreement with the energy defect (613 cm-1) for the considered process, and in fair agreement with the values which follow from recent theoretical calculations.

  16. New results from the NA57 experiment

    E-print Network

    G. E. Bruno; for the NA57 Collaboration

    2003-07-10

    We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 $A$ GeV/$c$ and 40 $A$ GeV/$c$. $\\Lambda$, $\\Xi$ and $\\Omega$ yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. $\\Lambda$, $\\Xi$, $\\Omega$\\ and preliminary $K_S^0$ transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model.

  17. The NA49 large acceptance hadron detector

    Microsoft Academic Search

    S V Afanasiev; T. Alber; H. Appelshäuser; J. Bächler; D. Barna; L. S. Barnby; Jerzy Bartke; R. A. Barton; L. Betev; H. Bialkowska; F. Bieser; A. Billmeier; C. O. Blyth; R K Böck; C. Bormann; J. Bracinik; F. P. Brady; R. Brockmann; R. Brun; P. Buncic; H. L. Caines; D. Cebra; G. E. Cooper; J. G. Cramer; P. Csato; M. Cyprian; J. Dunn; V. Eckardt; F. Eckhardt; T. Empl; J. Eschke; M. I. Ferguson; H. Fessler; H. G. Fischer; D. Flierl; Z. Fodor; Ulrich Frankenfeld; P Y Foka; P. Freund; V. Friese; J. Ftacnik; M. Fuchs; F. Gabler; J. Gal; R E Ganz; M. Gazdzicki; E Gladysz-Dziadus; J. Grebieszkow; J. Günther; J. W. Harris; S. Hegyi; T. Henkel; L. A. Hill; V. Hlinka; I. Huang; H. Hümmler; G. Igo; D. Irmscher; M. Ivanov; R. Janik; P. Jacobs; P. G. Jones; K. Kadija; V. I. Kolesnikov; M. Kowalski; B. Lasiuk; Peter Lévai; K. Liebicher; U. Lynen; A. I. Malakhov; S. Margetis; C. Markert; C. Marks; B W Mayes; G. L. Melkumov; A. Mock; J. Molnár; J. M. Nelson; M. Oldenburg; Grazyna Janina Odyniec; G. Palla; A. D. Panagiotou; Yu N Pestov; A. Petridis; M. Pikna; W. Pimpl; L. Pinsky; A. Piper; R. J. Porter; A. M. Poskanzer; S. Poziombka; D. J. Prindle; F. Pühlhofer; W. Rauch; J. G. Reid; R E Renfordt; W. Retyk; H. G. Ritter; D. Röhrich; C. Roland; G. Roland; H. Rudolph; A. Rybicki; T. Sammer; A. Sandoval; H. Sann; E. Schäfer; R. Schmidt; D. Schmischke; N. Schmitz; S. Schönfelder; A. Yu. Semenov; J. Seyboth; P. Seyboth; J. Seyerlein; F. Sikler; B. Sitar; E. Skrzypczak; G. T. A. Squier; H. Stelzer; Reinhard Stock; P. Strmen; H. Ströbele; C. Struck; T. Susa; I. Szarka; I. Szentpetery; P. Szymanski; J. Sziklai; M. Toy; T. A. Trainor; S. Trentalange; T S Ullrich; Maria Vassiliou; G I Veres; G. Vesztergombi; D. Vranic; F. Q. Wang; D. D. Weerasundara; S. Wenig; C. Whitten; H H Wieman; T. Wienold; L. Wood; T. A. Yates; J. Zimanyi; X.-Z. Zhu; R. Zybert

    1999-01-01

    The NA49 detector is a wide acceptance spectrometer for the study of hadron production in p+p, p+A, and A+A collisions at the CERN SPS. The main components are 4 large-volume TPCs for tracking and particle identification via dE\\/dx. TOF scintillator arrays complement particle identification. Calorimeters for transverse energy determination and triggering, a detector for centrality selection in p+A collisions, and

  18. The Na + \\/I ? Symporter (NIS): Recent Advances

    Microsoft Academic Search

    Orlie Levy; Antonio De la Vieja; Nancy Carrasco

    1998-01-01

    The Na+\\/I- symporter (NIS) catalyzes the accumulation of iodide into thyroid cells, an essential step in the biosynthesis of thyroid hormones. As a result of the isolation of the rat NIS cDNA, steadfast advances in the study of NIS at the molecular level have resulted in the following accomplishments: generation of high-affinity anti-NIS antibodies, elucidation of NIS stoichiometry and specificity

  19. Advanced Intermediate-Temperature Na-S Battery

    SciTech Connect

    Lu, Xiaochuan; Kirby, Brent W.; Xu, Wu; Li, Guosheng; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.; Yang, Zhenguo (Gary) [Gary

    2013-01-01

    In this study, we reported an intermediate-temperature (~150°C) sodium-sulfur (Na-S) battery. With a reduced operating temperature, this novel battery can potentially reduce the cost and safety issues associated with the conventional high-temperature (300~350°C) Na-S battery. A dense ?"-Al2O3 solid membrane and tetraglyme were utilized as the electrolyte separator and catholyte solvent in this battery. Solubility tests indicated that cathode mixture of Na2S4 and S exhibited extremely high solubility in tetraglyme (e.g., > 4.1 M for Na2S4 + 4 S). CV scans of Na2S4 in tetraglyme revealed two pairs of redox couples with peaks at around 2.22 and 1.75 V, corresponding to the redox reactions of polysulfide species. The discharge/charge profiles of the Na-S battery showed a slope region and a plateau, indicating multiple steps and cell reactions. In-situ Raman measurements during battery operation suggested that polysulfide species were formed in the sequence of Na2S5 + S ? Na2S5 + Na2S4? Na2S4 + Na2S2 during discharge and in a reverse order during charge. This battery showed dramatic improvement in rate capacity and cycling stability over room-temperature Na-S batteries, which makes it attractive for renewable energy integration and other grid related applications.

  20. Influence of Salt Purity on Na+ and Palmitic Acid Interactions

    E-print Network

    Influence of Salt Purity on Na+ and Palmitic Acid Interactions Zishuai Huang, Wei Hua, Dominique of salt purity on the interactions between Na+ ions and the carboxylate (COO- ) head group of palmitic frequency generation (VSFG) spectroscopy. Ultrapure (UP) and ACS grade NaCl salts are used for aqueous

  1. Topical Review Voltage Dependence of the Na/K Pump

    E-print Network

    Gadsby, David

    Topical Review Voltage Dependence of the Na/K Pump R.F. Rakowski1 , D.C. Gadsby2 , P. De Weer3 1, Philadelphia, PA 19104, USA Received: 2 August 1996/Revised: 13 September 1996 Introduction Whether Na/K pump & Rakowski, 1988). While it follows from first principles that the rate of net forward Na/K pumping must

  2. Coupling mechanism of the oxaloacetate decarboxylase Na + pump

    Microsoft Academic Search

    Peter Dimroth; Petra Jockel; Markus Schmid

    2001-01-01

    The oxaloacetate decarboxylase Na+ pump consists of subunits ?, ? and ?, and contains biotin as the prosthetic group. The peripheral ? subunit catalyzes the carboxyltransfer from oxaloacetate to the prosthetic biotin group to yield the carboxybiotin enzyme. Subsequently, this is decarboxylated in a Na+-dependent reaction by the membrane-bound ? subunit. The decarboxylation is coupled to Na+ translocation from the

  3. Ouabain Assembles Signaling Cascades through the Caveolar Na /K -ATPase*

    E-print Network

    Abraham, Nader G.

    membrane fractions. Consis- tently, ouabain induced the formation of a Na /K - ATPase-Src-caveolin complex -cyclodextrin or caveo- lin-1 by siRNA significantly reduced the caveolar Na / K -ATPase and Src. Concomitantly, cholesterol deple- tion abolished ouabain-induced recruitment of Src to the Na /K -ATPase signaling complex

  4. Electrophysiological effects of basolateral [Na+] in Necturus gallbladder epithelium

    Microsoft Academic Search

    GUILLERMO A. ALTENBERG; JAMES S. STODDARD

    1992-01-01

    In Necturus gallbladder epithelium, lowering serosal (Na ÷) ((Na+)3 reversibly hyperpolarized the basolateral cell membrane voltage (Vc,) and reduced the fractional resistance of the apical membrane (fR~). Previous results have suggested that there is no sizable basolateral Na + conductance and that there are apical Ca~+-activated K ÷ channels. Here, we studied the mechanisms of the electro- physiological effects of

  5. 1 nA Beam position monitor

    SciTech Connect

    Piller, M.; Flood, R.; Hammer, L.; Parks, M.; Strong, E.; Turlington, L.; Ursic, R. [Thomas Jefferson National Accelerator Facility (United States)

    1998-12-10

    A new BPM system, based on resonant cavities, has been developed for measuring the transverse position of very low-intensity electron beams delivered to Experimental Hall B at the Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News. VA. The system requirements called for measuring down to 1 nA with a 100 m m resolution. The actual system is much better: it can measure down to 100 pA at the 100 m m required resolution. A 100 pA beam yields about 1 electron per bunch. Each 1 nA BPM utilizes three resonant RF cavities to determine the position of the beam: one cavity sensitive to X position, a second cavity sensitive to Y position, and a third cavity which measures intensity. The position cavities operate at room temperature in a dipole type mode at 1497 MHz and contain internal field perturbing rods in an arrangement similar to that of the CEBAF rf Separator cavities. The position cavities are electron beam welded assemblies made of copper plated stainless steel. The RF output signal from each cavity is processed using a down-converter and a DSP based commercial lock-in amplifier operating at 100 kHz. The lock-in amplifiers connect to the EPICS control system via an IEEE 488 bus. System features under development include intensity and position modulation measurement capabilities. This paper provides measured performance results and an updated overview of the installed and operational 1 nA BPM system.

  6. Homocoordination preference in NaCs and LiNa liquid alloys by first principles molecular dynamics

    NASA Astrophysics Data System (ADS)

    Costa Cabral, B. J.; Martins, J. L.

    1999-09-01

    We present structural and dynamics results based on Hellman-Feynman molecular dynamics for the liquid phase of the NaCs alloy at two Na concentrations (cNa=0.6 and 0.8) and for the Li0.61Na0.39 zero alloy at two temperatures (T=590 K and 690 K). For NaCs the calculated structure factor S(k) is in very good agreement with data from neutron scattering experiments and the partial structure factors are compared to semiexperimental, theoretical and classical molecular dynamics predictions. We predict similar values for the self-diffusion coefficients of Na and Cs atoms in the Na0.6Cs0.4 alloy. For LiNa the concentration-concentration structure factor is in good agreement with experimental data and our results for the dynamics are compared with data from classical molecular dynamics simulations.

  7. Development of illumination optics and projection optics for high-NA EUV exposure tool (HiNA)

    Microsoft Academic Search

    Tetsuya Oshino; Masayuki Shiraishi; Noriaki Kandaka; Katsumi Sugisaki; Hiroyuki Kondo; Kazuya Ota; K. Mashima; Katsuhiko Murakami; Hiroaki Oizumi; Iwao Nishiyama; Shinji Okazaki

    2003-01-01

    We have developed a high numerical aperture (NA) small-field exposure system (HiNA) for EUV exposure process development. NA of projection optics of EUV exposure tools for 45-nm node lithography is expected to be around 0.25, which is higher than that previously expected (0.1). HiNA has compatible illumination system, which can be switched to partial coherent illumination and coherent illumination by

  8. Growth mechanism of NaClO 3 and NaBrO 3 crystals from aqueous solutions

    Microsoft Academic Search

    V. Surender; N. Arundhathi; K. Kishan Rao

    2006-01-01

    A study of growth rates of NaClO3 and NaBrO3 has been carried out using a small growth cell by in situ observation. Normal growth rates of (100) faces of NaClO3 and (111) faces of NaBrO3 along ?110? direction are measured under relatively high supersaturation ranging from 3–8%. In the initial stages of growth,\\u000a (100), (110) and (111) faces develop in

  9. Comparative studies of etching mechanisms of CR-39 in NaOH/H2O and NaOH/ethanol

    E-print Network

    Yu, K.N.

    Comparative studies of etching mechanisms of CR-39 in NaOH/H2O and NaOH/ethanol K.C.C. Tse, D Avenue, Kowloon Tong, Hong Kong Available online 13 May 2007 Abstract The bulk etch rate for CR-39 in NaOH/ethanol accumulates on the surface of CR-39 detector during etching in NaOH/ethanol, which is absent during etching

  10. Analytical Potential Energy Surface for the Na + HF NaF + H reaction: Application of Conventional Transition-State Theory

    E-print Network

    Analytical Potential Energy Surface for the Na + HF NaF + H reaction: Application of Conventional Campos, SP, CEP 12247-970, Brazil In this work we present the kinetic properties of the title reaction and the best two Na + HF analytical Potential Energy Surfaces(PES) found in literature: Bond Order 5(BO5

  11. Na+ channel function, regulation, structure, trafficking and sequestration.

    PubMed

    Chen-Izu, Ye; Shaw, Robin M; Pitt, Geoffrey S; Yarov-Yarovoy, Vladimir; Sack, Jon T; Abriel, Hugues; Aldrich, Richard W; Belardinelli, Luiz; Cannell, Mark B; Catterall, William A; Chazin, Walter J; Chiamvimonvat, Nipavan; Deschenes, Isabelle; Grandi, Eleonora; Hund, Thomas J; Izu, Leighton T; Maier, Lars S; Maltsev, Victor A; Marionneau, Celine; Mohler, Peter J; Rajamani, Sridharan; Rasmusson, Randall L; Sobie, Eric A; Clancy, Colleen E; Bers, Donald M

    2015-03-15

    This paper is the second of a series of three reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation-contraction coupling and arrhythmias: Na(+) channel and Na(+) transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on Na(+) channel function and regulation, Na(+) channel structure and function, and Na(+) channel trafficking, sequestration and complexing. PMID:25772290

  12. Use of ²³Na-nuclear magnetic resonance to follow sodium uptake and efflux in NaCl-adapted and nonadapted millet (Panicum miliaceum) suspensions

    Microsoft Academic Search

    L. O. Sillerud; J. W. Heyser

    1984-01-01

    Cellular Na\\/sup +\\/ transport was followed in vivo by ²³Na nuclear magnetic resonance (NMR) using anionic dysprosium-based shift reagents to resolve internal and external ²³Na\\/sup +\\/ resonances. Proso millet (Panicum miliaceum) cell suspensions adapted for rapid growth on 130 mM NaCl had biphasic ²³Na efflux kinetics when shifted to low Na..mu.. medium, while nonadapted cells had little measurable Na\\/sup +\\/

  13. Na+-pyrophosphatase: a novel primary sodium pump.

    PubMed

    Malinen, Anssi M; Belogurov, Georgiy A; Baykov, Alexander A; Lahti, Reijo

    2007-07-31

    Membrane-bound pyrophosphatase (PPase) is commonly believed to couple pyrophosphate (PPi) hydrolysis to H+ transport across the membrane. Here, we demonstrate that two newly isolated bacterial membrane PPases from the mesophile Methanosarcina mazei (Mm-PPase) and the moderate thermophile Moorella thermoacetica and a previously described PPase from the hyperthermophilic bacterium Thermotoga maritima catalyze Na+ rather than H+ transport into Escherichia coli inner membrane vesicles (IMV). When assayed in uncoupled IMV, the three PPases exhibit an absolute requirement for Na+ but display the highest hydrolyzing activity in the presence of both Na+ and K+. Steady-state kinetic analysis of PPi hydrolysis by Mm-PPase revealed two Na+ binding sites. One of these sites can also bind K+, resulting in a 10-fold increase in the affinity of the other site for Na+ and a 2-fold increase in maximal velocity. PPi-driven 22Na+ transport into IMV containing Mm-PPase was unaffected by the protonophore carbonyl cyanide m-chlorophenylhydrazone, inhibited by the Na+ ionophore monensin, and activated by the K+ ionophore valinomycin. The Na+ transport was accompanied by the generation of a positive inside membrane potential as reported by Oxonol VI. These findings define Na+-dependent PPases as electrogenic Na+ pumps. Phylogenetic analysis suggests that ancient gene duplication preceded the split of Na+- and H+-PPases. PMID:17605473

  14. Erythrocyte Na+/K+ ATPase activity measured with sup 23 Na NMR

    SciTech Connect

    Ouwerkerk, R.; van Echteld, C.J.; Staal, G.E.; Rijksen, G. (University Hospital, Utrecht (Netherland))

    1989-11-01

    A {sup 23}Na NMR assay for measurement of erythrocyte Na+/K+ ATPase activity is presented. Using the nonpermeant shift reagent dysprosium tripolyphosphate the signals of intra- and extracellular sodium are separated, enabling measurement of sodium fluxes nondestructively, without the need to physically separate the cells from their environment. By increasing membrane permeability with nystatin we have shown that the assay allows the detection of differences in membrane permeability. With low doses of nystatin the ouabain-sensitive sodium flux increased more than twofold. With high doses of nystatin the Na+/K+ pump could not prevent an almost total equilibration of intra- and extracellular sodium. All sodium that entered the cells remained NMR visible, proving that sodium influx can be measured quantitatively. {sup 31}P NMR spectra taken before and after the assay revealed a slight acidification of the cells and no significant change in ATP concentration. No evidence of Dy3+ entering the cell was observed.

  15. Standardization method of ²²Na using two NaI(Tl) scintillation detectors.

    PubMed

    Sato, Y; Yamada, T; Hasegawa, T

    2014-05-01

    A new standardization method for a sealed (22)Na point source was developed utilizing two NaI(Tl) scintillation detectors. In the proposed method, the count rates of annihilation radiation, gamma rays, their coincidence sum, and the coincidences between the two detectors are used. The equations from which the source activity can be deduced are derived in this work. A series of EGS-5 Monte Carlo calculations were conducted to test the validity of the expressions. The calculated activity agreed within approximately 1 percent with the literature data used as input in the simulations. PMID:24411317

  16. Photoionization of the alkali dimer cations Li+2, Na+2 and LiNa+

    NASA Astrophysics Data System (ADS)

    Dumitriu, Irina; Vanne, Yulian V.; Awasthi, Manohar; Saenz, Alejandro

    2007-05-01

    Photoionization cross sections for the three alkali dimer cations (Li+2, Na+2 and LiNa+) were calculated at the equilibrium internuclear distance for parallel, perpendicular and isotropic orientations of the molecular axis with respect to the field. A model-potential method was used for the description of the cores. The influence of the model-potential parameters on the photoionization spectra was investigated. Two different methods, a time-independent and a time-dependent one, were implemented and used for computing the cross sections.

  17. 1 nA Beam position monitor

    SciTech Connect

    Piller, M.; Flood, R.; Hammer, L.; Parks, M.; Strong, E.; Turlington, L.; Ursic, R. [Thomas Jefferson National Accelerator Facility (United States)

    1998-12-01

    A new BPM system, based on resonant cavities, has been developed for measuring the transverse position of very low-intensity electron beams delivered to Experimental Hall B at the Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News. VA. The system requirements called for measuring down to 1 nA with a 100 m m resolution. The actual system is much better: it can measure down to 100 pA at the 100 m m required resolution. A 100 pA beam yields about 1 electron per bunch. Each 1 nA BPM utilizes three resonant RF cavities to determine the position of the beam: one cavity sensitive to X position, a second cavity sensitive to Y position, and a third cavity which measures intensity. The position cavities operate at room temperature in a dipole type mode at 1497 MHz and contain internal field perturbing rods in an arrangement similar to that of the CEBAF rf Separator cavities. The position cavities are electron beam welded assemblies made of copper plated stainless steel. The RF output signal from each cavity is processed using a down-converter and a DSP based commercial lock-in amplifier operating at 100 kHz. The lock-in amplifiers connect to the EPICS control system via an IEEE 488 bus. System features under development include intensity and position modulation measurement capabilities. This paper provides measured performance results and an updated overview of the installed and operational 1 nA BPM system. {copyright} {ital 1998 American Institute of Physics.}

  18. 23Na Nuclear Spin-Lattice Relaxation Studies of Na2Ni2TeO6

    NASA Astrophysics Data System (ADS)

    Itoh, Yutaka

    2015-06-01

    We report on 23Na NMR studies of the honeycomb lattice antiferromagnet Na2Ni2TeO6 by 23Na nuclear spin-echo techniques. The 23Na nuclear spin-lattice relaxation rate 1/23T1 exhibits critical divergence near the Néel temperature TN = 26 K, a narrow critical region, and the critical exponent w = 0.34 in 1/23T1 ? (T/TN - 1)-w for Na2Ni2TeO6, and TN = 18 K for Na2(Ni0.5Cu0.5)2TeO6. Although the uniform magnetic susceptibility of Na2Ni2TeO6 exhibits a broad maximum at 35 K, which is the characteristic of low-dimensional spin systems, the NMR results indicate a three-dimensional criticalphenomenon near the Néel temperature.

  19. Optimised NASICON ceramics for Na + sensing

    Microsoft Academic Search

    R. O. Fuentes; F. Figueiredo; F. M. B. Marques; J. I. Franco

    2002-01-01

    NASICON dense ceramics were obtained from solid state reaction between SiO2, Na3PO412H2O and two different types of zirconia: monoclinic ZrO2 and the yttria-doped tetragonal phase (ZrO2)0.97(Y2O3)0.03. Higher temperatures were needed to obtain dense samples of the yttrium free composition (1265 C). The electrical conductivity,\\u000a at room temperature, of the yttria-doped samples sintered at 1230 C (0.20 S\\/m) is significantly higher

  20. Minimizing Load Effects on NA4 Gear Vibration Diagnostic Parameter

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.; Zakrajsek, James J.

    2001-01-01

    NA4 is a vibration diagnostic parameter, developed by researchers at NASA Glenn Research Center, for health monitoring of gears in helicopter transmissions. The NA4 reacts to the onset of gear pitting damage and continues to react to the damage as it spreads. This research also indicates NA4 reacts similarly to load variations. The sensitivity of NA4 to load changes will substantially affect its performance on a helicopter gearbox that experiences continuously changing load throughout its flight regimes. The parameter NA4 has been used to monitor gear fatigue tests at constant load. At constant load, NA4 effectively detects the onset of pitting damage and tracks damage severity. Previous research also shows that NA4 reacts to changes in load applied to the gears in the same way it reacts to the onset of pitting damage. The method used to calculate NA4 was modified to minimize these load effects. The modified NA4 parameter was applied to four sets of experimental data. Results indicate the modified NA4 is no longer sensitive to load changes, but remains sensitive to pitting damage.

  1. Apical Na+ permeability of frog skin during serosal Cl- replacement.

    PubMed

    Leibowich, S; DeLong, J; Civan, M M

    1988-05-01

    Gluconate substitution for serosal Cl- reduces the transepithelial short-circuit current (Isc) and depolarizes short-circuited frog skins. These effects could result either from inhibition of basolateral K+ conductance, or from two actions to inhibit both apical Na+ permeability (PapNa) and basolateral pump activity. We have addressed this question by studying whole-and split-thickness frog skins. Intracellular Na+ concentration (CcNa) and PapNa have been monitored by measuring the current-voltage relationship for apical Na+ entry. This analysis was conducted by applying trains of voltage pulses, with pulse durations of 16 to 32 msec. Estimates of PapNa and CcNa were not detectably dependent on pulse duration over the range 16 to 80 msec. Serosal Cl- replacement uniformly depolarized short-circuited tissues. The depolarization was associated with inhibition of Isc across each split skin, but only occasionally across the whole-thickness preparations. This difference may reflect the better ionic exchange between the bulk medium and the extracellular fluid in contact with the basolateral membranes, following removal of the underlying dermis in the split-skin preparations. PapNa was either unchanged or increased, and CcNa either unchanged or reduced after the anionic replacement. These data are incompatible with the concept that serosal Cl- replacement inhibits PapNa and Na,K-pump activity. Gluconate substitution likely reduces cell volume, triggering inhibition of the basolateral K+ channels, consistent with the data and conclusions of S.A. Lewis, A.G. Butt, M.J. Bowler, J.P. Leader and A.D.C. Macknight (J. Membrane Biol. 83:119-137, 1985) for toad bladder. The resulting depolarization reduces the electrical force favoring apical Na+ entry. The volume-conductance coupling serves to conserve volume by reducing K+ solute loss. Its molecular basis remains to be identified. PMID:2458472

  2. Na?La?(CO?)? and CsNa?Ca?(CO?)?: two new carbonates as UV nonlinear optical materials.

    PubMed

    Luo, Min; Wang, GenXiang; Lin, Chensheng; Ye, Ning; Zhou, Yuqiao; Cheng, Wendan

    2014-08-01

    Two nonlinear optical crystal carbonates (Na4La2(CO3)5 and CsNa5Ca5(CO3)8 were successfully synthesized by hydrothermal method, and both of them crystallized in the same noncentrosymmetric hexagonal space group P63mc (No. 186). The structure of Na4La2(CO3)5 consists of a three-dimensional network made up of [CO3] triangles as well as irregular [Na(0.67)La(0.33)O10] and [NaO8] polyhedra. The structure of CsNa5Ca5(CO3)8 can be described as the standing-on-edge [CO3] groups connect the adjacent infinite [CaCO3]? layers in the ab plane to construct a framework with four types of channels running parallel to [010]. The Na, Cs, and [Na(0.67)Ca(0.33)] atoms reside in these channels. The measurement of second harmonic generation (SHG) by the method adapted from Kurtz and Perry indicated that Na4La2(CO3)5 and CsNa5Ca5(CO3)8 were phase-matchable in the visible region and exhibited SHG responses of approximately 3 and 1 × KH2PO4 (KDP). Meanwhile, they exhibited wide transparent region with short UV cutoff edge at about 235 and 210 nm, respectively, suggesting that these crystals as NLO materials may have potential applications in the UV region. PMID:25027762

  3. Na+/H+ and Na+/NH4+ exchange activities of zebrafish NHE3b expressed in Xenopus oocytes

    PubMed Central

    Ito, Yusuke; Kato, Akira; Hirata, Taku; Hirose, Shigehisa

    2014-01-01

    Zebrafish Na+/H+ exchanger 3b (zNHE3b) is highly expressed in the apical membrane of ionocytes where Na+ is absorbed from ion-poor fresh water against a concentration gradient. Much in vivo data indicated that zNHE3b is involved in Na+ absorption but not leakage. However, zNHE3b-mediated Na+ absorption has not been thermodynamically explained, and zNHE3b activity has not been measured. To address this issue, we overexpressed zNHE3b in Xenopus oocytes and characterized its activity by electrophysiology. Exposure of zNHE3b oocytes to Na+-free media resulted in significant decrease in intracellular pH (pHi) and intracellular Na+ activity (aNai). aNai increased significantly when the cytoplasm was acidified by media containing CO2-HCO3? or butyrate. Activity of zNHE3b was inhibited by amiloride or 5-ethylisopropyl amiloride (EIPA). Although the activity was accompanied by a large hyperpolarization of ?50 mV, voltage-clamp experiments showed that Na+/H+ exchange activity of zNHE3b is electroneutral. Exposure of zNHE3b oocytes to medium containing NH3/NH4+ resulted in significant decreases in pHi and aNai and significant increase in intracellular NH4+ activity, indicating that zNHE3b mediates the Na+/NH4+ exchange. In low-Na+ (0.5 mM) media, zNHE3b oocytes maintained aNai of 1.3 mM, and Na+-influx was observed when pHi was decreased by media containing CO2-HCO3? or butyrate. These results provide thermodynamic evidence that zNHE3b mediates Na+ absorption from ion-poor fresh water by its Na+/H+ and Na+/NH4+ exchange activities. PMID:24401990

  4. A primary respiratory Na+ pump of an anaerobic bacterium: the Na+-dependent NADH:quinone oxidoreductase of Klebsiella pneumoniae.

    PubMed

    Dimroth, P; Thomer, A

    1989-01-01

    Membranes of Klebsiella pneumoniae, grown anaerobically on citrate, contain a NADH oxidase activity that is activated specifically by Na+ or Li+ ions and effectively inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Cytochromes b and d were present in the membranes, and the steady state reduction level of cytochrome b increased on NaCl addition. Inverted bacterial membrane vesicles accumulated Na+ ions upon NADH oxidation. Na+ uptake was completely inhibited by monensin and by HQNO and slightly stimulated by carbonylcyanide-p-trifluoromethoxy phenylhydrazone (FCCP), thus indicating the operation of a primary Na+ pump. A Triton extract of the bacterial membranes did not catalyze NADH oxidation by O2, but by ferricyanide or menadione in a Na+-independent manner. The Na+-dependent NADH oxidation by O2 was restored by adding ubiquinone-1 in micromolar concentrations. After inhibition of the terminal oxidase with KCN, ubiquinol was formed from ubiquinone-1 and NADH. The reaction was stimulated about 6-fold by 10 mM NaCl and was severely inhibited by low amounts of HQNO. Superoxide radicals were formed during electron transfer from NADH to ubiquinone-1. These radicals disappeared by adding NaCl, but not with NaCl and HQNO. It is suggested that the superoxide radicals arise from semiquinone radicals which are formed by one electron reduction of quinone in a Na+-independent reaction sequence and then dismutase in a Na+ and HQNO sensitive reaction to quinone and quinol. The mechanism of the respiratory Na+ pump of K. pneumoniae appears to be quite similar to that of Vibrio alginolyticus. PMID:2545175

  5. Na + -fast ionic conducting glass-ceramics of silicophosphates

    Microsoft Academic Search

    Toshinori Okura; Hideki Monma; Kimihiro Yamashita

    2010-01-01

    The Na+-fast ionic conducting glass-ceramics with Na5YSi4O12 (N5)-type structure were successfully synthesized using the composition formula of Na3+3x-y\\u000a R1-x\\u000a P\\u000a y\\u000a Si3-y\\u000a O9 for a variety of rare earth ions, R, under the appropriate composition parameters. In the crystallization of N5-type glass-ceramics, its relatives (Na3YSi3O9 (N3)- and Na9YSi6O18 (N9)-type glass-ceramics) structurally belonging to the family of Na24?3x\\u000a Y\\u000a x\\u000a Si12O36

  6. Dissolution and Recrystallization of GaN in Molten Na

    NASA Astrophysics Data System (ADS)

    Aoki, Masato; Yamane, Hisanori; Shimada, Masahiko; Sarayama, Seiji; Iwata, Hirokazu; Disalvo, Francis J.

    2003-12-01

    The dissolution mass of GaN in molten Na at 650-800°C and 3-5 MPa of N2 was determined by weight loss of polycrystalline GaN fragments immersed in Na and by chemical analysis of the amount of Ga dissolved in Na. The dissolution of GaN in Na was equilibrated within 100 h and the dissolution mass increased with increasing temperature but decreased with increasing N2 pressure. It was found that the addition of a small amount of Li3N into the Na melt increased the dissolution mass of GaN. Transparent platelet single crystals of GaN with sizes over 300 ?m were grown from nutrient GaN powder by cooling a Na solution with a Li3N additives from 800°C to 700°C at 1°C/h.

  7. Pyrophosphate-Fueled Na+ and H+ Transport in Prokaryotes

    PubMed Central

    Malinen, Anssi M.; Luoto, Heidi H.

    2013-01-01

    SUMMARY In its early history, life appeared to depend on pyrophosphate rather than ATP as the source of energy. Ancient membrane pyrophosphatases that couple pyrophosphate hydrolysis to active H+ transport across biological membranes (H+-pyrophosphatases) have long been known in prokaryotes, plants, and protists. Recent studies have identified two evolutionarily related and widespread prokaryotic relics that can pump Na+ (Na+-pyrophosphatase) or both Na+ and H+ (Na+,H+-pyrophosphatase). Both these transporters require Na+ for pyrophosphate hydrolysis and are further activated by K+. The determination of the three-dimensional structures of H+- and Na+-pyrophosphatases has been another recent breakthrough in the studies of these cation pumps. Structural and functional studies have highlighted the major determinants of the cation specificities of membrane pyrophosphatases and their potential use in constructing transgenic stress-resistant organisms. PMID:23699258

  8. Mechanism of inhibition of alanine absorption by Na ricinoleate.

    PubMed

    Hajjar, J J; Murphy, D M; Scheig, R L

    1979-05-01

    The mechanism of inhibition of alanine absorption by Na ricinoleate has been examined in the rabbit intestine. This fatty acid in a concentration of 2--5 mM inhibits alanine absorption in vivo and in vitro. The inhibition is more evident in the jejunum than in the ileum. Strips of ileal mucosa treated with Na ricinoleate gain Na. Sodium ricinoleate inhibits alanine influx across rabbit ileum, even in the presence of a sodium gradient across these cells. The results suggest that the main action of Na ricinoleate is on the alanine-transport system at the brush-border membrane. The fatty acid may also inhibit amino acid absorption by increasing intestinal cell Na concentration, which results in a decreased Na gradient across the brush-border membrane. PMID:443374

  9. Multielectron removal processes in He{sup 2+}+Na collisions

    SciTech Connect

    Knoop, S.; Hasan, V. G.; Morgenstern, R.; Hoekstra, R. [KVI, Atomic Physics, Rijksuniversiteit Groningen, Zernikelaan 25, NL-9747 AA, Groningen (Netherlands)

    2006-06-15

    Multielectron processes have been studied by measuring the Na{sup 2+} and Na{sup 3+} recoil momenta resulting from 10 keV/amu He{sup 2+}+Na(3s) collisions. The Na{sup 2+} Q-value spectrum shows that transfer ionization dominates two-electron removal. Double capture populates mostly singly excited He(1snl) states. A smaller fraction of double capture leads to doubly excited He. Na{sup 3+} recoil ions are created by double capture into the He ground state and the emission of a third electron into the continuum. The Na{sup 3+} recoil ion is not left in its triplet ground state but in one of the low-lying excited singlet terms due to spin conservation.

  10. Magnesium correction to the NaKCa chemical geothermometer

    USGS Publications Warehouse

    Fournier, R.O.; Potter, R.W., II

    1979-01-01

    Equations and graphs have been devised to correct for the adverse effects of magnesium upon the Na-K-Ca chemical geothermometer. Either the equations or graphs can be used to determine appropriate temperature corrections for given waters with calculated NaKCa temperatures > 70??C and R 50 are probably derived from relatively cool aquifers with temperatures approximately equal to the measured spring temperature, irrespective of much higher calculated Na-K-Ca temperatures. ?? 1979.

  11. Simulation of Na D emission near Europa during eclipse

    USGS Publications Warehouse

    Cassidy, T.A.; Johnson, R.E.; Geissler, P.E.; Leblanc, F.

    2008-01-01

    The Cassini imaging science subsystem observed Europa in eclipse during Cassini's Jupiter flyby. The disk-resolved observations revealed a spatially nonuniform emission in the wavelength range of 200-1050 nm (clear filters). By building on observations and simulations of Europa's Na atmosphere and torus we find that electron-excited Na in Europa's tenuous atmosphere can account for the observed emission if the Na is ejected preferentially from Europa's dark terrain. Copyright 2008 by the American Geophysical Union.

  12. Aggregate centres of Ag - ions in KCl : Na crystals

    NASA Astrophysics Data System (ADS)

    Tsuboi, T.; Zota, S.; Topa, V.

    2001-01-01

    Not only (Ag -) 2 and Ag -(Na +) centres but also various Ag --Na + aggregate centres have been produced in Ag +-, Na +- and Ca 2+-codoped KCl crystals by unusual electrolytic colouration such as colouration at a relatively low temperature of 280°C and a high electric field of 5000 V/cm. Absorption and magnetic circular dichroism spectra due to these centres have been investigated.

  13. Molecular genetics of the human Na + \\/glucose cotransporter

    Microsoft Academic Search

    M. A. Hediger; E. Turk; A. M. Pajor; E. M. Wright

    1989-01-01

    Summary Recent success in expression cloning has revealed the primary structure of the Na+\\/glucose cotransporter from rabbit small intestine, and this has subsequently led to the cloning of the Na+\\/glucose cotransporters from human small intestine and human kidney. Close homology is evident between the rabbit and human intestinal Na+\\/glucose cotransporters at the DNA level, and the predicted amino acid and

  14. Use of /sup 23/Na-nuclear magnetic resonance to follow sodium uptake and efflux in NaCl-adapted and nonadapted millet (Panicum miliaceum) suspensions

    SciTech Connect

    Sillerud, L.O.; Heyser, J.W.

    1984-05-01

    Cellular Na/sup +/ transport was followed in vivo by /sup 23/Na nuclear magnetic resonance (NMR) using anionic dysprosium-based shift reagents to resolve internal and external /sup 23/Na/sup +/ resonances. Proso millet (Panicum miliaceum) cell suspensions adapted for rapid growth on 130 mM NaCl had biphasic /sup 23/Na efflux kinetics when shifted to low Na..mu.. medium, while nonadapted cells had little measurable Na/sup +/ efflux after preloading with /sup 23/NaCl. Uptake of /sup 23/Na was also observed using /sup 23/Na NMR. The resonance frequency of the external Na/sup +/-dysprosium (III) triphosphate, relative to that of the /sup 23/Na in the cells, was sensitive to pH, permitting the pH of the external medium to be followed during the course of in vivo experiments. 20 references, 3 figures.

  15. Use of Na-Nuclear Magnetic Resonance To Follow Sodium Uptake and Efflux in NaCl-Adapted and Nonadapted Millet (Panicum miliaceum) Suspensions.

    PubMed

    Sillerud, L O; Heyser, J W

    1984-05-01

    Cellular Na(+) transport was followed in vivo by (23)Na nuclear magnetic resonance (NMR) using anionic dysprosium-based shift reagents to resolve internal and external (23)Na(+) resonances. Proso millet (Panicum miliaceum) cell suspensions adapted for rapid growth on 130 mm NaCl had biphasic (23)Na efflux kinetics when shifted to low Na(+) medium, while nonadapted cells had little measurable Na(+) efflux after preloading with (23)NaCl. Uptake of (23)Na was also observed using (23)Na NMR. The resonance frequency of the external Na(+)-dysprosium (III) triphosphate, relative to that of the (23)Na in the cells, was sensitive to pH, permitting the pH of the external medium to be followed during the course of in vivo experiments. PMID:16663592

  16. Effects of Cl adatom on Na-Decorated graphene

    NASA Astrophysics Data System (ADS)

    Song, Xinxiang; Sun, Yu; Dong, Meifeng; Li, Chun; Wang, Jiesheng; Mimura, Hidenori; Yuan, Guang

    2015-06-01

    The effects of the Cl adatom on Na-decorated graphene are studied using first principles density functional theory under the generalized gradient approximation to calculate the adsorption energy, geometric structure, charge density difference, and density of states. When Na and Cl adatoms are simultaneously absorbed on opposite sides of graphene, the adsorption energy of Na increases by about 1?eV and the adsorption system becomes more stable because graphene can effectively transfer the 3s valence of the Na adatom to the Cl adatom.

  17. First-principles calculations study of Na adsorbed on silicene

    NASA Astrophysics Data System (ADS)

    Guo, Xi-Xi; Guo, Ping; Zheng, Ji-Ming; Cao, Li-Ke; Zhao, Pu-Ju

    2015-06-01

    Geometry, electronic structure, and diffusion properties of Na atom on the pristine and single vacancy-defected silicene sheet have been systematically investigated by using density functional theory with generalized gradient approximation. The most stable positions of Na atom on the perfect and the defected silicene sheet are determined, and four diffusion paths have been explored. The minimum diffusion barrier of Na atom is 0.25 eV on pristine silicene, and 1.44 eV on single vacancy-defected silicene sheet. The vacancy exhibits a more significant influence than the adsorption of the Na atom on the electronic structure of silicene.

  18. Atomic motions in an unusual molecular semiconductor: NaSn

    NASA Astrophysics Data System (ADS)

    Stoddard, Ronald Dean; Conradi, Mark S.; McDowell, A. F.; Saboungi, Marie-Louise; Price, David Long

    1995-11-01

    Recent investigations of the compound NaSn (1:1) have indicated that both fast conduction of Na+ cations and rapid reorientations of (Sn4)4- anions are present in the high-temperature solid phase, ?-NaSn. We have used 23Na and 119Sn nuclear magnetic resonance to separately monitor the motions of Na and Sn in the low-temperature ordered solid phase, ?-NaSn, where the correlation times of the motions are much longer. The Na+ motions are evident in T1, T1?, T2, and T*2 (linewidth) 23Na data at magnetic fields of 8.0 and 2.0 T. The Na motions are described by a single time constant with thermal activation parameters Ea/kB=9700 K and ?D(?)=1.7×1014 s-1. Sn motions are evident in T2, line shape, and stimulated echo data taken at 8.0 T. 119Sn stimulated echo data unequivocally show the Sn motion to be reorientations of Sn4 tetrahedra; any diffusion of Sn between tetrahedra is much slower. The combined T2 and stimulated echo data for 119Sn demonstrate that the Sn4 reorientations are thermally activated with Ea/kB=13 800 K and ?R(?)=2.3×1015 s-1. The temperature dependence of the 119Sn T1 fits an activation energy of 7000 K; the Sn T1 is believed to be due to thermally activated charge carriers.

  19. Study of OSL in NaF: Ca,Cu

    NASA Astrophysics Data System (ADS)

    More, Y. K.; Wankhede, S. P.; Moharil, S. V.

    2013-06-01

    Sodium Fluoride containing Cu+ ions was prepared by R.A.P. followed by melt-quenching technique. Results on photo, thermo and optically stimulated luminescence in NaF:Ca,Cu are reported. OSL sensitivity of NaF:Ca,Cu is approximately 2 times than that of standard phosphor LMP. The rate of OSL depletion for 90% decay for NaF:Ca,Cu is 0.3 times as that of OSL phosphor LMP. NaF:Ca,Cu thus deserves much more attention than it has received up till now.

  20. Pion and kaon freezeout in NA44

    SciTech Connect

    NA44 Collaboration

    1994-12-01

    The NA44 spectrometer is optimized for the study of single and two-particle particle spectra near mid-rapidity for transverse momenta below {approx} 1 GeV/c. A large fraction of all pairs in the spectrometer`s acceptance are at low relative momenta, resulting in small statistical uncertainties on the extracted size parameters. In addition, the spectrometer`s clean particle identification allows the authors to measure correlation functions for pions, kaons, and protons. This contribution will concentrate on the source size parameters determined from pion and kaon correlation functions. These size parameters will be compared to calculations from the RQMD event generator and also interpreted in the context of a hydrodynamic model. Finally, the measured single particle spectra will be examined from the viewpoint of hydrodynamics.

  1. New results from the NA57 experiment

    E-print Network

    G. E. Bruno; for the NA57 Collaboration

    2004-04-05

    The production of hyperons in Pb-Pb and p-Be interaction at 40 A GeV/c beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 A GeV/c are presented for the first time and compared to those measured at 158 A GeV/c. The transverse mass spectra of high statistics, high purity samples of K0_short, Lambda, Xi and Omega particles produced in Pb-Pb collisions at 158 A GeV/c have been studied in the framework of the blast-wave model. The dependence of the freeze-out parameters on particle species and event centrality is discussed.

  2. The NA49 large acceptance hadron detector

    E-print Network

    Afanasiev, S V; Appelshäuser, H; Bächler, J; Barna, D; Barnby, L S; Bartke, Jerzy; Barton, R A; Betev, L; Bialkowska, H; Bieser, F; Billmeier, A; Blyth, C O; Böck, R K; Bormann, C; Bracinik, J; Brady, F P; Brockmann, R; Brun, R; Buncic, P; Caines, H L; Cebra, D; Cooper, G E; Cramer, J G; Csató, P; Cyprian, M; Dunn, J; Eckardt, V; Eckhardt, F; Empl, T; Eschke, J; Ferguson, M I; Fessler, H; Fischer, H G; Flierl, D; Fodor, Z; Frankenfeld, Ulrich; Foka, P Y; Freund, P; Friese, V; Ftácnik, J; Fuchs, M; Gabler, F; Gál, J; Ganz, R E; Gazdzicki, M; Gladysz-Dziadus, E; Grebieszkow, J; Günther, J; Harris, J W; Hegyi, S; Henkel, T; Hill, L A; Hlinka, V; Huang, I; Hümmler, H; Igo, G; Irmscher, D; Ivanov, M; Janik, R; Jacobs, P; Jones, P G; Kadija, K; Kolesnikov, V I; Kowalski, M; Lasiuk, B; Lévai, Peter; Liebicher, K; Lynen, U; Malakhov, A I; Margetis, S; Markert, C; Marks, C; Mayes, B W; Melkumov, G L; Mock, A; Molnár, J; Nelson, J M; Oldenburg, M; Odyniec, Grazyna Janina; Pálla, G; Panagiotou, A D; Pestov, Yu N; Petridis, A; Pikna, M; Pimpl, W; Pinsky, L; Piper, A; Porter, R J; Poskanzer, A M; Poziombka, S; Prindle, D J; Pühlhofer, F; Rauch, W; Reid, J G; Renfordt, R E; Retyk, W; Ritter, H G; Röhrich, D; Roland, C; Roland, G; Rudolph, H; Rybicki, A; Sammer, T; Sandoval, A; Sann, H; Schäfer, E; Schmidt, R; Schmischke, D; Schmitz, N; Schönfelder, S; Semenov, A Yu; Seyboth, J; Seyboth, P; Seyerlein, J; Siklér, F; Sitár, B; Skrzypczak, E; Squier, G T A; Stelzer, H; Stock, Reinhard; Strmen, P; Ströbele, H; Struck, C; Susa, T; Szarka, I; Szentpétery, I; Szymanski, P; Sziklai, J; Toy, M; Trainor, T A; Trentalange, S; Ullrich, T S; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wang, F; Weerasundara, D D; Wenig, S; Whitten, C; Wieman, H H; Wienold, T; Wood, L; Yates, T A; Zimányi, J; Zhu, X Z; Zybert, R

    1999-01-01

    The NA49 detector is a wide acceptance spectrometer for the study of hadron production in p+p, p+A, and A+A collisions at the CERN SPS. The main components are 4 large volume TPCs for tracking and particle identification via $dE/dx$. TOF scintillator arrays complement particle identification. Calorimeters for transverse energy determination and triggering, a detector for centrality selection in p+A collisions, and beam definition detectors complete the set-up. A description of all detector components is given with emphasis on new technical realizations. Performance and operational experience are discussed in particular with respect to the high track density environment of central Pb+Pb collisions.

  3. Mercury's Na Exosphere from MESSENGER data

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary M.; Burger, M. H.; Cassidy, T. A.; Sarantos, M.; Vervack, R. J.; McClintock, W. E.; Merkel, A. W.; Sprague, A. L.; Solomon, S. C.

    2012-10-01

    MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UVVS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft to infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The hot portion of the source appears to be highly variable. The authors acknowledge support from NASA through the MESSENGER Participating Scientist Program and Planetary Atmospheres research grants.

  4. Dependence of thermoluminescence in LiF:Mg,Cu,Na,Si phosphor on Na dopant concentration and thermal treatment

    Microsoft Academic Search

    Kaiyong Tang

    2003-01-01

    A new phosphor, LiF:Mg,Cu,Na,Si, has been developed in this laboratory for thermoluminescence. The thermoluminescence dependence on the concentration of Na dopant between 0 mol% and 0.45 mol% and thermal treatment between 240°C and 310°C was investigated. With an increase of Na concentration, the TL sensitivity and the main peak increase when the annealing temperature is less than 300°C. With an

  5. A primary respiratory Na + pump of an anaerobic bacterium: the Na + -dependent NADH:quinone oxidoreductase of Klebsiella pneumoniae

    Microsoft Academic Search

    Peter Dimroth; Anna Thomer

    1989-01-01

    Membranes of Klebsiella pneumoniae, grown anaerobically on citrate, contain a NADH oxidase activity that is activated specifically by Na+ or Li+ ions and effectively inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Cytochromes b and d were present in the membranes,\\u000a and the steady state reduction level of cytochrome b increased on NaCl addition. Inverted bacterial membrane vesicles accumulated\\u000a Na+ ions upon NADH oxidation.

  6. Microhardness studies on as-grown faces of NaClO 3 and NaBrO 3 crystals

    Microsoft Academic Search

    K. Kishan Rao; V. Surender; B. Saritha Rani

    2002-01-01

    Single crystals of NaClO3 and NaBrO3 are grown from their aqueous solutions at a constant temperature of 35°C by slow evaporation by using good quality seed crystals.\\u000a Systematic microhardness studies are made on as-grown faces of these crystals at various loads. Typical cracks are observed\\u000a at the corners of the impressions in NaClO3 whereas in addition to the cracks at

  7. Auxiliar de raios x -Pagamento de horas extras A Seo Especializada em Dissdios Individuais (SDI-1) do Tribunal Superior do

    E-print Network

    Floeter, Sergio Ricardo

    auxiliar de raios-x, lotada no serviço de radiologia e recebendo adicional de insalubridade. Em sua ação atividades perigosas, e relatou informação de um técnico de radiologia de que não havia equipamentos de, entendendo que a Lei nº 3.999/1961 não se aplica ao auxiliar de radiologia. Ambas as partes recorreram ao

  8. The effect of NaCl/g/ on the Na2SO4-induced hot corrosion of NiAl

    NASA Technical Reports Server (NTRS)

    Smeggil, J. G.; Bornstein, N. S.; Decrescente, M. A.

    1977-01-01

    Studies have been performed to examine the effect of NaCl vapor on the Na2SO4-induced hot corrosion of the alumina former NiAl. In the incubation period associated with such hot corrosion, NaCl(g) has been shown to be effective in removing aluminum from below the protective alumina scale and redepositing it as Al2O3 whiskers on the surface of the Na2SO4-coated sample. Similar effects seen in simple oxidation are associated with isothermal rupturing of the protective alumina scale.

  9. [Effect of K(+) on Na (+) fluxes and transport in barley roots: K(+)-stimulated Na (+) efflux in the root cortex].

    PubMed

    Jeschke, W D

    1972-03-01

    Barley roots grown on a nutrient solution containing 1 mM Na(+) but no K(+) are capable of a considerable Na(+) transport via the symplasm of the root and the xylem vessels. K(+) added to the medium surrounding the root cortex severely inhibits this transport after a lag period at a high rate constant (Fig. 3).It is likely that the fluxes of Na(+) are changed drastically during this transition from low to high K(+) status. Although originally limited to steady state fluxes, the extended method of efflux analysis for excised roots (Pitman, 1971) has been applied to the non-steady fluxes which occur upon the addition of K(+) to the roots. It is shown that besides other changes the efflux of (22)Na(+) through the cortex of barley roots is stimulated instantaneously (Fig. 5) by the addition of K(+) and presumably by an influx of K(+) ions. From this a transient, K(+)-stimulated Na(+) efflux at the plasmalemma of the cortical cells can be estimated. It amounts to 10.9 ? moles/g fw · h compared to the control efflux of 3.3 ? moles/g fw · h without K(+).The stimulated efflux is attributed to a Na(+) efflux pump at the plasmalemma and is thus related to the K-Na-selectivity of barley plants. The inhibition of the Na(+) transport by K(+) is probably a consequence of this increased efflux of Na(+) from the symplasm through the root cortex. PMID:24477899

  10. Thermal variation of the rotatory power of crystals of NaClO 3 and NaBrO 3

    Microsoft Academic Search

    M. S. Madhava

    1970-01-01

    The thermal variation of rotatory power of crystals of NaClO3 and NaBrO3 has been measured in the visible and ultraviolet region of the spectrum. The rotatory power of NaClO3\\u000a increases on heating whereas that of NaBrO3\\u000a decreases. On the other hand the refractive index decreases with rise of temperature for both crystals. The observations are shown\\u000a to be consistent with

  11. Electron spectrometric study of the internal energy distribution in Na2+ for single beam associative ionization

    Microsoft Academic Search

    H. A. J. Meijer; S. Schohl; M. W. Muller; H. Dengel; M.-W. Ruf; H. Hotop

    1991-01-01

    We present the internal energy distribution of Na: molecular ions formed in the associative ionization (AI) reactions Na(3p)+NaOp)+ Na:+e- and Na(4d)+ Na(3s)+ Na:+e-, as measured in a single beam by electron spectrometry. In both reactions the population of the higher vibrational levels is favoured. The cross section of the second reaction is found to he about two orders of magnitude

  12. Complete Bromide Surface Segregation in Mixed NaCl /NaBr Aerosols Grown from Droplets

    NASA Astrophysics Data System (ADS)

    Antonsson, Egill; Patanen, Minna; Nicolas, Christophe; Neville, John J.; Benkoula, Safia; Goel, Alok; Miron, Catalin

    2015-01-01

    Sea-salt aerosols are a source of atmospheric bromine responsible for ozone depletion. The availability of bromine from sea-salt aerosols to heterogeneous phase chemical reactions is determined by its local concentration at the aerosol surface. We report here complete surface segregation of bromine in mixed NaCl /NaBr aerosols grown by drying droplets, thus mimicking the atmospheric process by which solid sea-salt aerosols are generated. For d =70 nm solid aerosols, complete surface segregation is observed for solution Br /Cl ratios below 2%. These findings set a size-dependent upper limit on the bromine surface enrichment that can be reached in solid salt aerosols grown from sea-water droplets in the atmosphere.

  13. The effects of eslicarbazepine on persistent Na? current and the role of the Na? channel ? subunits.

    PubMed

    Doeser, Anna; Soares-da-Silva, Patricio; Beck, Heinz; Uebachs, Mischa

    2014-02-01

    Eslicarbazepine is the major active metabolite of eslicarbazepine acetate, a once-daily antiepileptic drug approved in Europe as adjunctive therapy for refractory partial-onset seizures in adults. This study was aimed to determine the effects of eslicarbazepine on persistent Na(+) currents (INaP) and the role of ? subunits in modulating these effects. To study the role of ? subunits of the Na(+) channel we used a mouse line genetically lacking either the ?1 or ?2 subunit, encoded by the SCN1B or SCN2B gene, respectively. Whole cell patch-clamp recordings were performed on CA1 neurons in hippocampal slices under control conditions and application of 300 ?M eslicarbazepine. We examined INaP in acutely isolated CA1 neurons and repetitive firing in hippocampal slices of mice lacking ? subunits and corresponding wild-type littermates. We found that eslicarbazepine caused a significant reduction of maximal INaP conductance and an efficient reduction of the firing rate in wild-type mice. We have shown previously a paradoxical increase of conductance of INaP caused by carbamazepine in mice lacking ?1 subunits in the subthreshold range, leading to a failure in affecting neuronal firing (Uebachs et al., 2010). In contrast, eslicarbazepine did not cause this paradoxical effect on INaP in SCN1B null mice. Consequently, the effects of eslicarbazepine on repetitive firing were maintained in these animals. These results indicate that eslicarbazepine exerts effects on INaP similar to those known for carbamazepine. However, in animals lacking the ?1 Na(+) channel subunit these effects are maintained. Therefore, eslicarbazepine potentially overcomes a previously described putative mechanism of resistance to established Na(+) channel acting antiepileptic drugs. PMID:24368131

  14. Na+/myo-inositol symporters and Na+/H+-antiport in Mesembryanthemum crystallinum.

    PubMed

    Chauhan, S; Forsthoefel, N; Ran, Y; Quigley, F; Nelson, D E; Bohnert, H J

    2000-11-01

    Mitr1 and Mitr2 from Mesembryanthemum crystallinum (common ice plant) are members of a family of genes homologous to H+[or Na+]/myo-inositol symporters (ITRs), not previously studied in plants. MITR1 complemented an Itr1-deficient yeast strain. Mitr1 is strongly expressed in roots, moderately in stems, and weakly in leaves. Its transcripts increased in all organs, most dramatically in roots, under salinity stress. Mitr2 constitutes a rare transcript, slightly upregulated by salt stress in leaves only. Mitr1 transcripts are present in all cells in the root tip, but become restricted to phloem-associated cells in mature roots. Peptide antibodies against the two proteins indicated the presence of MITR1 in all organs and of MITR2 in leaves. Both are located in the tonoplast. MITR1 acts in removing sodium from root vacuoles, correlated with findings of low root sodium, while leaf vacuoles accumulate sodium in the ice plant. Up-regulation in leaves and stems is also found for Na+/H+-antiporter (Nhx-type) transcripts. Under comparable stress conditions, Nhx-and Itr-like transcripts in Arabidopsis were regulated differently. In the ice plant, co-ordinate induction of Na+/H+-antiporters and Na+/myo-inositol symporters transfers sodium from vacuoles in root cells into the leaf mesophyll as a halophytic strategy that lowers the osmotic potential. The tissue-specific differential expression of Itr- and Nhx-type transcripts suggests that the vacuolar sodium/inositol symporters function to reduce sodium amounts in cells of the root and vascular tissue, while sodium/proton antiporters in leaf tissues function to partition sodium into vacuoles for storage. PMID:11115132

  15. Electrical conductivity and dielectric properties of polypyrrole/Na+-montmorillonite (PPy/Na+-MMT) clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Rizvi, Tasneem Zahra; Shakoor, Abdul

    2009-05-01

    Frequency dependent ac conductivity (?ac), dielectric constant (?') and loss factor (?'') have been measured in the frequency range 100-106 Hz in polypyrrole/Na+-montmorillonite (PPy/Na+-MMT) clay nanocomposites. The nanocomposites were synthesized by in situ polymerization of pyrrole with varying amounts of Na+-MMT from 0.2 to 1.0 wt% in the presence of FeCl3 · 6H2O in an aqueous medium. All three measured quantities; ?ac, ?' and ?'' increased with the increase in MMT content in the composites at all frequencies. The frequency dependence of ?ac displayed a low frequency region of almost constant conductivity below 104 Hz, while above this frequency a rapid rise in ?ac was observed with the increase in frequency obeying a power law of frequency dependence with an exponent equal to 1. Both real and imaginary parts of the permittivity exhibited a low frequency dispersion which has been attributed to hopping of polarons and bipolarons in PPy and its composites.

  16. Moderate temperature rechargeable NaNiS2 cells

    NASA Technical Reports Server (NTRS)

    Abraham, K. M.

    1983-01-01

    A rechargeable sodium battery of the configuration, liquid Na/beta double prime -Al2O3/molten NaAlCl4, NiS2, operating in the temperature range of 170 to 190 C, is described. This battery is capable of delivering or = to 50 W-hr/1b and 1000 deep discharge/charge cycles.

  17. Pulse shape discrimination with a large NaI crystal

    NASA Astrophysics Data System (ADS)

    Doll, P.; Fink, G.; Haupenthal, M.; Finlay, R. W.; Hauber, S.; Klages, H. O.; Schieler, H.; Smend, F.; Wicke, G.-D.

    1989-12-01

    A large NaI Crystal (16 × 16 × 24 cm 3) is operated in a combined neutron and gamma-ray field in the energy range from 12 to 36 MeV. Pulse shape discrimination is employed to separate (n, charged particles) reaction products in NaI. Fluorescence efficiencies for various charged particles are studied.

  18. Adaptation of Tobacco Cells to NaCl 1

    PubMed Central

    Binzel, Marla L.; Hasegawa, Paul M.; Handa, Avtar K.; Bressan, Ray A.

    1985-01-01

    Cell lines of tobacco (Nicotiana tabacum L. var Wisconsin 38) were obtained which are adapted to grow in media with varying concentrations of NaCl, up to 35 grams per liter (599 millimolar). Salt-adapted cells exhibited enhanced abilities to gain both fresh and dry weight in the presence of NaCl compared to cells which were growing in medium without NaCl (unadapted cells). Tolerance of unadapted cells and cells adapted to 10 grams per liter NaCl was influenced by the stage of growth, with the highest degree of tolerance exhibited by cells in the exponential phase. Cell osmotic potential and turgor varied through the growth cycle of unadapted cells and cells at all levels of adaptation, with maximum turgor occurring at approximately the onset of exponential fresh weight accumulation. Adaptation to NaCl led to reduced cell expansion and fresh weight gain, while dry weight gain remained unaffected. This reduction in cell expansion was not due to failure of the cells to maintain turgor since cells adapted to NaCl underwent osmotic adjustment in excess of the change in water potential caused by the addition of NaCl to the medium. Tolerance of the adapted cells, as indicated by fresh or dry weight gain, did not increase proportionately with the increase in turgor. Adaptation of these glycophytic cells to NaCl appears to involve mechanisms which result in an altered relationship between turgor and cell expansion. Images Fig. 3 PMID:16664356

  19. Branching ratios for the beta decay of Na-21

    E-print Network

    Iacob, V. E.; Hardy, John C.; Gagliardi, Carl A.; Goodwin, J.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Tribble, Robert E.; Zhai, Y.; Towner, I. S.

    2006-01-01

    We have measured the beta-decay branching ratio for the transition from Na-21 to the first excited state of Ne-21. A recently published test of the standard model, which was based on a measurement of the beta-nu correlation in the decay of Na-21...

  20. Resurgent current of voltage-gated Na(+) channels.

    PubMed

    Lewis, Amanda H; Raman, Indira M

    2014-11-15

    Resurgent Na(+) current results from a distinctive form of Na(+) channel gating, originally identified in cerebellar Purkinje neurons. In these neurons, the tetrodotoxin-sensitive voltage-gated Na(+) channels responsible for action potential firing have specialized mechanisms that reduce the likelihood that they accumulate in fast inactivated states, thereby shortening refractory periods and permitting rapid, repetitive, and/or burst firing. Under voltage clamp, step depolarizations evoke transient Na(+) currents that rapidly activate and quickly decay, and step repolarizations elicit slower channel reopening, or a 'resurgent' current. The generation of resurgent current depends on a factor in the Na(+) channel complex, probably a subunit such as NaV?4 (Scn4b), which blocks open Na(+) channels at positive voltages, competing with the fast inactivation gate, and unblocks at negative voltages, permitting recovery from an open channel block along with a flow of current. Following its initial discovery, resurgent Na(+) current has been found in nearly 20 types of neurons. Emerging research suggests that resurgent current is preferentially increased in a variety of clinical conditions associated with altered cellular excitability. Here we review the biophysical, molecular and structural mechanisms of resurgent current and their relation to the normal functions of excitable cells as well as pathophysiology. PMID:25172941

  1. Transepithelial Na+ transport and the intracellular fluids: a computer study.

    PubMed

    Civan, M M; Bookman, R J

    1982-01-01

    Computer simulations of tight epithelia under three experimental conditions have been carried out, using the rheogenic nonlinear model of Lew, Ferreira and Moura (Proc. Roy. Soc. London. B 206:53-83, 1979) based largely on the formulation of Koefoed-Johnsen and Ussing (Acta Physiol. Scand. 42: 298-308. 1958). First, analysis of the transition between the short-circuited and open-circuited states has indicated that (i) apical Cl- permeability is a critical parameter requiring experimental definition in order to analyze cell volume regulation, and (ii) contrary to certain experimental reports, intracellular Na+ concentration (ccNa) is expected to be a strong function of transepithelial clamping voltage. Second, analysis of the effects of lowering serosal K+ concentration (csK) indicates that the basic model cannot simulate several well-documented observations; these defects can be overcome, at least qualitatively, by modifying the model to take account of the negative feedback interaction likely to exist between the apical Na+ permeability and ccNa. Third, analysis of the strongly supports the concept that osmotically induced permeability changes in the apical intercellular junctions play a physiological role in conserving the body's stores of NaCl. The analyses also demonstrate that the importance of Na+ entry across the basolateral membrane is strongly dependent upon transepithelial potential, cmNa and csK; under certain conditions, net Na+ entry could be appreciably greater across the basolateral than across the apical membrane. PMID:7057462

  2. The putative mechanism of Na+ absorption in euryhaline

    E-print Network

    Evans, David H.

    The putative mechanism of Na+ absorption in euryhaline elasmobranchs exists in the gills of a stenohaline marine elasmobranch, Squalus acanthias Keith P. Choe a,b,, Susan L. Edwards b,c , James B for active Na+ absorption. However, the vast majority of elasmobranchs are only found in marine environments

  3. Direct Measurement of {sup 21}Na+{alpha} Stellar Reaction

    SciTech Connect

    Binh, D. N.; Kubono, S.; Yamaguchi, H.; Hayakawa, S.; Hashimoto, T.; Kahl, D. [Center for Nuclear Study (CNS), University of Tokyo (Japan); Teranishi, T. [Department of Physics, Kuyshu University (Japan); Iwasa, N.; Kume, N. [Department of Physics, Tohoku University (Japan); Kato, S. [Department of Physics, Yamagata University (Japan); Khiem, L. H.; Tho, N. T. [Institute of Physics, Vietnamese Academy of Science and Technology (Viet Nam); Wakabayashi, Y. [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA) (Japan)

    2010-08-12

    The measurement of the resonant alpha scattering and the {sup 21}Na({alpha}, p) reaction were performed for the first time in inverse kinematics with the thick target method using a {sup 21}Na radioisotope (RI) beam. This paper reports the current result of alpha scattering measurement and its astrophysics implication.

  4. The Na-K-ATPase and Calcium-Signaling Microdomains

    NSDL National Science Digital Library

    Jiang Tian (University of Toledo Health Science Campus Physiology and Pharmacology)

    2008-08-01

    The Na-K-ATPase is an energy-transducing ion pump that converts the free energy of ATP into transmembrane ion gradients. It also serves as a functional receptor for cardiotonic steroids such as ouabain and digoxin. Binding of ouabain to the Na-K-ATPase can activate calcium signaling in a cell-specific manner. The exquisite calcium modulation via the Na-K-ATPase is achieved by the ability of the pump to integrate signals from numerous protein and non-protein molecules, including ion transporters, channels, protein kinases/phosphatases, as well as cellular Na+. This review focuses on the unique properties of the Na-K-ATPase and its role in the formation of different calcium-signaling microdomains.

  5. LiNa5Mo9O30

    PubMed Central

    Hamza, Hamadi; Ennajeh, Ines; Zid, Mohamed Faouzi; Driss, Ahmed

    2012-01-01

    The tite compound, lithium penta­sodium nona­molybdate, LiNa5Mo9O30, was synthesized by solid-state reaction. The three-dimensional [Mo9O30]6? framework is built up from MoO6 octa­hedra and MoO5 bipyramids, linked together by edges and corners. The framework delimits two types of inter­secting tunnels running along [100] and [010] in which the Na+ and Li+ ions are located. The asymmetric unit contains one Mo, one Na and one Li site located on a twofold rotation axis. The crystal studied was a racemic twin with site a twin ratio of 0.51?(10):0.49?(10). Relationships between the structures of K2Mo3O10, K2Mo4O13, Cs2Mo7O22, Na6Mo10O33 and Na6Mo11O36 compounds are discussed. PMID:23284311

  6. Binding energy and geometry of e^+Na

    NASA Astrophysics Data System (ADS)

    Shertzer, Janine; Ward, S. J.

    2010-03-01

    We calculate the non-adiabatic binding energy and geometry of the weakly bound state of e^+Na. We use the Peach model potential to describe the e^+-Na^+ and e^--Na^+ interactions and solve the effective three-body Schrödinger equation with the finite element method. Because the model potential gives rise to three spurious states (corresponding to 1s, 2s, and 2p), the true non-adiabatic ground state of e^+Na is embedded in a dense spectrum of spurious states. We developed a technique for extracting the correct ground state for e^+Na, even when the energy is nearly degenerate with a spurious level. This is the first calculation to include the quadrupole term in the polarization potential.

  7. Study of acoustic activity of NaBrO3

    NASA Astrophysics Data System (ADS)

    Lin, Lin Quan; Tao, Fang; Shen, Zhi Gong; Ma, Wen Yi

    1987-05-01

    Acoustic activity in NaBrO3 has been studied by measurement of the degeneracy splitting of transverse acoustic waves with neutron scattering. The splitting ?? is proportional to wave vector q, instead of q2. It is the first sample which cannot be explained by phenomenological theory on acoustic activity. An additional study of NaBr0.7Cl0.3O3 showed that NaBrO3 and NaClO3 have opposite senses in acoustic activity. Further study of NaBrxCl1-xO3 may lead to a new subject which is concerned with the similar phenomenon in acoustics as in ferromagnetism.

  8. Uncertainties for ^22Na production in ONe novae

    NASA Astrophysics Data System (ADS)

    Wrean, P. R.; D'Auria, J. M.

    1999-10-01

    We report preliminary results using network calculations on the uncertainty for the production of ^22Na in ONe novae due to the uncertainty in the reaction rates in the hot Ne-Na cycle. We have varied the rates for the nine reactions of the Ne-Na cycle within their uncertainties, and have run all permutations of upper and lower limits for the Ne-Na reactions. Our fast-running code uses temperature-density profiles generated by a full hydro- and thermodynamic treatment of ONe novae (José, Coc and Hernanz, astro-ph/9902357). The reaction rates were taken from the recent compilation of the NACRE collaboration, Thielemann's REACLIB library, and several recent experimental and theoretical papers. We also pinpoint the nuclear reactions which contribute most to the uncertainty in the final ^22Na abundances.

  9. The regio- and stereo-selective reduction of steroidal 4-en-3-ones using Na?S?O?/NaHCO? and CuCl/NaBH?.

    PubMed

    Wang, Chunli; Chen, Xiaoyu; Huang, Yaoqing; Yang, Jesse; Chen, Ying

    2013-12-20

    This paper describes the regio- and stereoselective reduction of ??-3-keto moiety in certain steroids using Na?S?O?/NaHCO? and CuCl/NaBH?, respectively. Using either one of the two reduction agents in the reaction, the 17-substituents in the D ring were observed to have clearly influenced the stereoselective reduction of 4-ene in the A ring by the so-called conformational transmission effect. Na?S?O?/NaHCO? regioselectively reduced CC at 4-position of 17-substituted-androst-4-en-3-one derivatives to 5?-H-3-one as the main isomer. And as an extended application, Epiandrosterone (11) was further synthesized from androst-4-en-3,17-dione (AD) via four steps. The total yield from this was about 45%. In the presence of CuCl/NaBH?, ??-3-keto conjugated reduction of 17-spirocyclic ethylene ketal protected androst-4-en-3-one derivatives mainly produced 3?-hydroxy-5?-H isomers, at a yield around 81%. Considering the scaffold configuration of 3?-hydroxy-5?-H moiety coincided with that of bile acid analogs, this selective reduction could also be used as an alternative method for the synthetic study of bile acids using AD and its derivatives, which are from the microorganism degradation of natural sterols, as the potential materials. Meanwhile, configurations of the reductive compounds 5b, 6b, 9, 10 and 17e were identified by X-ray diffraction. PMID:24128809

  10. Genome Sequences of Cupriavidus metallidurans Strains NA1, NA4, and NE12, Isolated from Space Equipment

    PubMed Central

    Monsieurs, Pieter; Mijnendonckx, Kristel; Provoost, Ann; Venkateswaran, Kasthuri; Ott, C. Mark; Leys, Natalie

    2014-01-01

    Cupriavidus metallidurans NA1, NA4, and NE12 were isolated from space and spacecraft-associated environments. Here, we report their draft genome sequences with the aim of gaining insight into their potential to adapt to these environments. PMID:25059868

  11. Effects of oligomycin on transient currents carried by Na+ translocation of Bufo Na+/K(+)-ATPase expressed in Xenopus oocytes.

    PubMed

    Ding, Yanli; Hao, Jingping; Rakowski, Robert F

    2011-10-01

    Na(+)/K(+)-ATPase (NKA) exports 3Na(+) and imports 2K(+) at the expense of the hydrolysis of 1ATP under physiological conditions. In the absence of K(+), it can mediate electroneutral Na(+)/Na(+) exchange. In the electroneutral Na(+)/Na(+) exchange mode, NKA produces a transient current containing fast, medium and slow components in response to a sudden voltage step. These three components of the transient current demonstrate the sequential release of Na(+) ions from three binding sites. Our data from oocytes provide further experimental support for the existence of these components. Oligomycin is an NKA inhibitor that favors the 2Na(+)-occluded state without affecting the conformational state of the NKA. We studied the effects of oligomycin on both K(+)-activated currents and transient currents in wild-type Bufo NKA and a mutant form of Bufo NKA, NKA: G813A. Oligomycin blocked almost all of the K(+)-activated current, although the three components of the transient current showed different sensitivities to oligomycin. The oligomycin-inhibited charge movement measured using a P/4 protocol had a rate coefficient similar to the medium transient component. The fast component of the transient current elicited by a short voltage step also showed sensitivity to oligomycin. However, the slow component was not totally inhibited by oligomycin. Our results indicate that the second and third sodium ions might be released to the extracellular medium by a mechanism that is not shared by the first sodium ion. PMID:21877177

  12. Two-step K Na and Ag Na ion-exchanged glass waveguides for C-band applications

    E-print Network

    Chen, Ray

    Two-step K ­Na and Ag ­Na ion-exchanged glass waveguides for C-band applications Jizuo Zou, Feng single-mode channel waveguides in BK7 glass for the telecom-wavelength region. The dependencies of insertion loss, polarization-dependent loss PDL , and bending loss of a curved waveguide on channel width

  13. NaO anticorrelation and horizontal branches. II. The NaO anticorrelation in the globular cluster NGC 6752

    Microsoft Academic Search

    E. Carretta; A. Bragaglia; R. G. Gratton; S. Lucatello; Y. Momany

    2007-01-01

    We are studying the Na-O anticorrelation in several globular clusters of different Horizontal Branch (HB) morphology in order to derive a possible relation between (primordial) chemical inhomogeneities and morphological parameters of the cluster population. We used the multifiber spectrograph FLAMES on the ESO Very Large Telescope UT2 and derived atmospheric parameters and elemental abundances of Fe, O and Na for

  14. A semiclassical study of laser-induced atomic fluorescence from Na2, K2 and NaK

    NASA Technical Reports Server (NTRS)

    Yuan, J.-M.; Bhattacharyya, D. K.; George, T. F.

    1982-01-01

    A semiclassical treatment of laser-induced atomic fluorescence for the alkali-dimer systems Na2, K2 and NaK is presented. The variation of the fluorescence intensity with the frequency of the exciting laser photon is studied and a comparison of theoretical results with a set of experimental data is presented.

  15. Otoczenie spoleczne i jego wplyw na wyniki ekonomiczne przedsibiorstwa na przykladzie instytucji nonprofit wiadczcej uslugi lecznicze i rehabilitacyjne.

    E-print Network

    Paris-Sud XI, Université de

    _wyniki_ekonomiczne_przedsi_biorstwa_na_przyk_adzie_instytucji_nonpr ofit_wiadcz_cej_us_ugi_lecznicze_i_rehabilitacyjne_autorstwa_K_Szagdaja_A_Miks a/888478 Recenzja 2: N_wyniki_ekonomiczne_przedsi_biorstwa_na_przyk_adzie_instytucji_nonpr ofit_wiadcz_cej_us_ugi_lecznicze_i_rehabilitacyjne_autorstwa_K_Szagdaja_Recenzj a_2_N_Wenc_a/888477 hal

  16. A Raman and MAS NMR study of mixed alkali Na–K and Na–Li aluminoborosilicate glasses

    Microsoft Academic Search

    N. Ollier; T. Charpentier; B. Boizot; G. Wallez; D. Ghaleb

    2004-01-01

    Structural studies of two types of aluminoborosilicate glasses (Na\\/K and Na\\/Li) using Raman and NMR spectroscopy are presented. Both types of glasses display a mixed alkali effect (MAE) according to electrical conductivity and Tg measurements. Concerning the glass structure and more particularly the silicate network, our results show that the MAE slightly affects the glass polymerization degree, which displays a

  17. Genome Sequences of Cupriavidus metallidurans Strains NA1, NA4, and NE12, Isolated from Space Equipment.

    PubMed

    Monsieurs, Pieter; Mijnendonckx, Kristel; Provoost, Ann; Venkateswaran, Kasthuri; Ott, C Mark; Leys, Natalie; Van Houdt, Rob

    2014-01-01

    Cupriavidus metallidurans NA1, NA4, and NE12 were isolated from space and spacecraft-associated environments. Here, we report their draft genome sequences with the aim of gaining insight into their potential to adapt to these environments. PMID:25059868

  18. Status for 2015, CERN NA63

    E-print Network

    Mikkelsen, RE; Wistisen, T

    2015-01-01

    We summarize the status for the CERN NA63 collaboration, where in 2015 we have had two runs at the CERN SPS, beamline H4: One with Ar ions at various energies around 75 GeV per nucleon, and one with electrons/positrons of 10-20 GeV. We previously refined and updated our theoretical analyses of bremsstrahlung and delta-electron emission from heavy, and medium-heavy, ultrarelativistic nuclei \\cite{Mikk15}. We thus concluded that - although not quite as interesting as for Pb projectiles - projectiles of Ar and/or Xe were suitable for the investigation, and for establishing the method to eventually measure the charge distribution of short-lived ($ct\\gtrsim3$m) fragments \\cite{Mikk14}. However, as the preliminary data analysis shows, the signal - which requires an intact projectile - is about three orders of magnitude lower than the background, stemming from photon emission (possibly originating from $\\pi^0$'s) in coincidence with projectiles that most likely are not intact after the collision. With the presently ...

  19. Tritium separation from Pb-17Li by permeation into Na or NaK and cold trapping

    SciTech Connect

    Reimann, J.

    1988-09-01

    The tritium extraction technique considered for a fusion reactor with a self-cooled Pb-17 Li blanket includes the permeation of the tritium into a Na or NaK intermediate loop and the precipitation as tritide in a cold trap. Tritium is recovered by thermal decomposition under vacuum. Basic kinetic studies of the thermal decomposition of sodium hydride are presented using different types of hydrides. The temperature range investigated was between 280 and 420/sup 0/C. Using fine NaH powder, the rate constants agreed well with those from other authors. For NaH crystals, the rate constants were lower by one order of magnitude and were similar to those obtained previously for coarse NaH powder.

  20. Preparation of Al-La Master Alloy by Thermite Reaction in NaF-NaCl-KCl Molten Salt

    NASA Astrophysics Data System (ADS)

    Jang, Poknam; Li, Hyonmo; Kim, Wenjae; Wang, Zhaowen; Liu, Fengguo

    2015-05-01

    A NaF-NaCl-KCl ternary system containing La2O3 was investigated for the preparation of Al-La master alloy by the thermite reaction method. The solubility of La2O3 in NaF-NaCl-KCl molten salt was determined by the method of isothermal solution saturation. Inductively coupled plasma-optical emission spectroscopy and x-ray diffraction (XRD) analyses were used to consider the content of La2O3 in molten salt and the supernatant composition of molten salt after dissolution of La2O3, respectively. The results showed that the content of NaF had a positive influence on the solubility of La2O3 in NaF-NaCl-KCl molten salts, and the solubility of La2O3 could reach 8.71 wt.% in molten salts of 50 wt.%NaF-50 wt.% (44 wt.%NaCl + 56 wt.%KCl). The XRD pattern of cooling molten salt indicated the formation of LaOF in molten salt, which was probably obtained by the reaction between NaF and La2O3. The kinetic study showed that the thermite reaction was in accord with a first-order reaction model. The main influence factors on La content in the Al-La master alloy product, including molten salt composition, amount of Al, concentration of La2O3, stirring, reduction time and temperature, were investigated by single-factor experimentation. The content of La in the Al-La master alloy could be reached to 10.1 wt.%.

  1. A mutation in Na(+)-NQR uncouples electron flow from Na(+) translocation in the presence of K(+).

    PubMed

    Shea, Michael E; Mezic, Katherine G; Juárez, Oscar; Barquera, Blanca

    2015-01-20

    The sodium-pumping NADH:ubiquinone oxidoreductase (Na(+)-NQR) is a bacterial respiratory enzyme that obtains energy from the redox reaction between NADH and ubiquinone and uses this energy to create an electrochemical Na(+) gradient across the cell membrane. A number of acidic residues in transmembrane helices have been shown to be important for Na(+) translocation. One of these, Asp-397 in the NqrB subunit, is a key residue for Na(+) uptake and binding. In this study, we show that when this residue is replaced with asparagine, the enzyme acquires a new sensitivity to K(+); in the mutant, K(+) both activates the redox reaction and uncouples it from the ion translocation reaction. In the wild-type enzyme, Na(+) (or Li(+)) accelerates turnover while K(+) alone does not activate. In the NqrB-D397N mutant, K(+) accelerates the same internal electron transfer step (2Fe-2S ? FMNC) that is accelerated by Na(+). This is the same step that is inhibited in mutants in which Na(+) uptake is blocked. NqrB-D397N is able to translocate Na(+) and Li(+), but when K(+) is introduced, no ion translocation is observed, regardless of whether Na(+) or Li(+) is present. Thus, this mutant, when it turns over in the presence of K(+), is the first, and currently the only, example of an uncoupled Na(+)-NQR. The fact the redox reaction and ion pumping become decoupled from each other only in the presence of K(+) provides a switch that promises to be a useful experimental tool. PMID:25486106

  2. Rigidification of the autolysis loop enhances Na+ binding to thrombin

    PubMed Central

    Pozzi, Nicola; Chen, Raymond; Chen, Zhiwei; Bah, Alaji; Di Cera, Enrico

    2011-01-01

    Binding of Na+ to thrombin ensures high activity toward physiological substrates and optimizes the procoagulant and prothrombotic roles of the enzyme in vivo. Under physiological conditions of pH and temperature, the binding affinity of Na+ is weak due to large heat capacity and enthalpy changes associated with binding, and the Kd=80 mM ensures only 64% saturation of the site at the concentration of Na+ in the blood (140 mM). Residues controlling Na+ binding and activation have been identified. Yet, attempts to improve the interaction of Na+ with thrombin and possibly increase catalytic activity under physiological conditions have so far been unsuccessful. Here we report how replacement of the flexible autolysis loop of human thrombin with the homologous rigid domain of the murine enzyme results in a drastic (up to 10-fold) increase in Na+ affinity and a significant improvement in the catalytic activity of the enzyme. Rigidification of the autolysis loop abolishes the heat capacity change associated with Na+ binding observed in the wild-type and also increases the stability of thrombin. These findings have general relevance to protein engineering studies of clotting proteases and trypsin-like enzymes. PMID:21536369

  3. Hormonal regulation of Na -K -ATPase in cultured epithelial cells

    SciTech Connect

    Johnson, J.P.; Jones, D.; Wiesmann, W.P.

    1986-08-01

    Aldosterone and insulin stimulate Na transport through mechanisms involving protein synthesis. Na -K -ATPase has been implicated in the action of both hormones. The authors examined the effect of aldosterone and insulin on Na -K -ATPase in epithelial cells in culture derived from toad urinary bladder (TB6C) and toad kidney (A6). Aldosterone, but not insulin, increases short-circuit current (I/sub sc/) in TB6C cells. Aldosterone increases Na -K -(TSP)ATPase activity after 18 h of incubation, but no effect can be seen at 3 and 6 h. Amiloride, which inhibits aldosterone-induced increases in I/sub sc/, has no effect on either basal or aldosterone stimulated enzyme activity. Both aldosterone and insulin increase I/sub sc/ in A6 cells and when added together are synergistic. Aldosterone stimulates enzyme activity in A6 cells, but insulin alone has no effect. However, aldosterone and insulin together stimulate enzyme activity more than aldosterone alone. It appears that stimulation of Na -K -ATPase activity is involved in aldosterone action in both cell lines but does not appear to be due to increased Na entry, since enhanced enzyme activity is not inhibited by amiloride. In contrast, insulin alone has no direct effect on Na -K -ATPase, although the increased enzyme activity following both agents in combination may explain their synergism on I/sub sc/.

  4. Na+-sulfate cotransporter SLC13A1.

    PubMed

    Markovich, Daniel

    2014-01-01

    Sulfate is essential for normal physiology. The kidney plays a major role in sulfate homeostasis. Sulfate is freely filtered and strongly reabsorbed in the proximal tubule. The apical membrane Na(+)-sulfate cotransporter NaS1 (SLC13A1) mediates sulfate (re)absorption across renal proximal tubule and small intestinal epithelia. NaS1 encodes a 595-amino acid (? 66 kDa) protein with 13 putative transmembrane domains. Its substrate preferences are sodium and sulfate, thiosulfate, and selenate, and its activity is inhibited by molybdate, selenate, tungstate, thiosulfate, succinate, and citrate. NaS1 is primarily expressed in the kidney (proximal tubule) and intestine (duodenum to colon). NaS1 expression is down-regulated in the renal cortex by high sulfate diet, hypothyroidism, vitamin D depletion, glucocorticoids, hypokalemia, metabolic acidosis, and NSAIDs and up-regulated by low sulfate diet, thyroid hormone, vitamin D supplementation, growth hormone, chronic renal failure, and during post-natal growth. Disruption of murine NaS1 gene leads to hyposulfatemia and hypersulfaturia, as well as changes in metabolism, growth, fecundity, behavior, gut physiology, and liver detoxification. This suggests that NaS1 is an important sulfate transporter and its disruption leads to perturbed sulfate homeostasis, which contributes to numerous pathophysiological conditions. PMID:24193406

  5. Targeting Na(+) /K(+) -translocating adenosine triphosphatase in cancer treatment.

    PubMed

    Durlacher, Cameron T; Chow, Kevin; Chen, Xiao-Wu; He, Zhi-Xu; Zhang, Xueji; Yang, Tianxin; Zhou, Shu-Feng

    2015-05-01

    The Na(+) /K(+) -translocating adenosine triphosphatase (ATPase) transports sodium and potassium across the plasma membrane and represents a potential target in cancer chemotherapy. Na(+) /K(+) -ATPase belongs to the P-type ATPase family (also known as E1-E2 ATPase), which is involved in transporting certain ions, metals, and lipids across the plasma membrane of mammalian cells. In humans, the Na(+) /K(+) -ATPase is a binary complex of an ?-subunit that has four isoforms (?1 -?4 ) and a ?-subunit that has three isoforms (?1 -?3 ). This review aims to update our knowledge on the role of Na(+) /K(+) -ATPase in cancer development and metastasis, as well as on how Na(+) /K(+) -ATPase inhibitors kill tumour cells. The Na(+) /K(+) -ATPase has been found to be associated with cancer initiation, growth, development, and metastasis. Cardiac glycosides have exhibited anticancer effects in cell-based and mouse studies via inhibition of the Na(+) /K(+) -ATPase and other mechanisms. Na(+) /K(+) -ATPase inhibitors may kill cancer cells via induction of apoptosis and autophagy, radical oxygen species production, and cell cycle arrest. They also modulate multiple signalling pathways that regulate cancer cell survival and death, which contributes to their antiproliferative activities in cancer cells. The clinical evidence supporting the use of Na(+) /K(+) -ATPase inhibitors as anticancer drugs is weak. Several phase I and phase II clinical trials with digoxin, Anvirzel, and huachansu (an intravenous formulated extract of the venom of the wild toad), either alone or more often in combination with other anticancer agents, have shown acceptable safety profiles but limited efficacy in cancer patients. Well-designed randomized clinical trials with reasonable sample sizes are certainly warranted to confirm the efficacy and safety of cardiac glycosides for the treatment of cancer. PMID:25739707

  6. In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3

    E-print Network

    Wang, Zhong L.

    In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3 Jong the phase transformation from a Sandia octahedral molecular sieve Na2Nb2O6-H2O to a piezoelectric NaNbO3 at high temperatures. After dehydration at 288 °C, the Na2Nb2O6-H2O becomes significantly destabilized

  7. Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) using NaY and AgNaY zeolites for fuel cell applications

    Microsoft Academic Search

    Doohwan Lee; Eun-Yong Ko; Hyun Chul Lee; Soonho Kim; Eun Duck Park

    2008-01-01

    Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) that are widely used sulfur odorants in pipeline natural gas was studied using AgNa-Y zeolites at ambient temperature and atmospheric pressure. The AgNa-Y were obtained via Ag+-exchange with Na+ of Na-Y at various exchange levels, and the contributions of formed adsorption sites (Ag+, Na+, Ag0, H+, and Ag2O) in the THT and

  8. Effects of Na2MoO4 and Na2WO4 on molybdenum and tungsten electrodes for the alkali metal thermoelectric converter (AMTEC)

    Microsoft Academic Search

    R. M. Williams; B. L. Wheeler; B. Jeffries-Nakamura; M. E. Loveland; C. P. Bankston

    1988-01-01

    The effects of adding Na2MoO4 and Na2WO4 to porous Mo and W electrodes, respectively, on the performance and impedance characteristics of the electrodes in an alkali metal thermoelectric converter (AMTEC) were investigated. It was found that corrosion of the porous electrode by Na2MoO4 or Na2WO4 to form Na2MO3O6 and WO2, respectively, and recrystallization of the Mo or W as the

  9. Investigation of phase equilibria in the system Nd 2O 3–Na 2O–P 2O 5. The partial system NdPO 4–Na 4P 2O 7–NaPO 3

    Microsoft Academic Search

    Teresa Znamierowska; Szymon Bandrowski

    2008-01-01

    The NdPO4–Na4P2O7–NaPO3 system being part of the Nd2O3–Na2O–P2O5 oxide system was investigated by thermoanalytical methods, X-ray powder diffraction and microscopy in reflected light. On the basis of the obtained results its phase diagram is proposed. The investigated partial system is bounded by three subsystems (i) NdPO4–NaPO3, (ii) Na4P2O7–NaPO3 and (iii) NdPO4–Na4P2O7. In the system NdPO4–NaPO3 an intermediate compound – NaNdP2O7

  10. Gat1 (Gaba:Na+:Cl?) Cotransport Function

    PubMed Central

    Lu, Chin-Chih; Hilgemann, Donald W.

    1999-01-01

    Neurotransmitter transporters are reported to mediate transmembrane ion movements that are poorly coupled to neurotransmitter transport and to exhibit complex “channel-like” behaviors that challenge the classical “alternating access” transport model. To test alternative models, and to develop an improved model for the Na+- and Cl?-dependent ?-aminobutyric acid (GABA) transporter, GAT1, we expressed GAT1 in Xenopus oocytes and analyzed its function in detail in giant membrane patches. We detected no Na+- or Cl?- dependent currents in the absence of GABA, nor did we detect activating effects of substrates added to the trans side. Outward GAT1 current (“reverse” transport mode) requires the presence of all three substrates on the cytoplasmic side. Inward GAT1 current (“forward” transport mode) can be partially activated by GABA and Na+ on the extracellular (pipette) side in the nominal absence of Cl?. With all three substrates on both membrane sides, reversal potentials defined with specific GAT1 inhibitors are consistent with the proposed stoichiometry of 1GABA:2Na+:1Cl?. As predicted for the “alternating access” model, addition of a substrate to the trans side (120 mM extracellular Na+) decreases the half-maximal concentration for activation of current by a substrate on the cis side (cytoplasmic GABA). In the presence of extracellular Na+, the half-maximal cytoplasmic GABA concentration is increased by decreasing cytoplasmic Cl?. In the absence of extracellular Na+, half-maximal cytoplasmic substrate concentrations (8 mM Cl?, 2 mM GABA, 60 mM Na+) do not change when cosubstrate concentrations are reduced, with the exception that reducing cytoplasmic Cl? increases the half-maximal cytoplasmic Na+ concentration. The forward GAT1 current (i.e., inward current with all extracellular substrates present) is inhibited monotonically by cytoplasmic Cl? (Ki, 8 mM); cytoplasmic Na+ and cytoplasmic GABA are without effect in the absence of cytoplasmic Cl?. In the absence of extracellular Na+, current–voltage relations for reverse transport current (i.e., outward current with all cytoplasmic substrates present) can be approximated by shallow exponential functions whose slopes are consistent with rate-limiting steps moving 0.15–0.3 equivalent charges. The slopes of current–voltage relations change only little when current is reduced four- to eightfold by lowering each cosubstrate concentration; they increase twofold upon addition of 100 mM Na+ to the extracellular (pipette) side. PMID:10469733

  11. Two-frequency lidar technique for mesospheric Na temperature measurements

    NASA Technical Reports Server (NTRS)

    She, C. Y.; Latifi, H.; Yu, J. R.; Alvarez, R. J., II; Bills, R. E.

    1990-01-01

    This paper describes a new two-frequency lidar for measuring Na temperature profiles. The laser oscillator is tuned to the two operating frequencies by observing the Doppler-free structure of the Na D2 fluorescence spectrum in a vapor cell. The lidar technique and initial observations of the temperature profile between 82 and 102 km are described. Absolute temperature accuracies at the Na layer peak of better than + or - 3 K with a vertical resolution of 1 km and an integration period of approximately 5 min were achieved.

  12. The incommensurately modulated structures of the perovskites NaCeMnWO6 and NaPrMnWO6.

    PubMed

    García-Martín, Susana; King, Graham; Nénert, Gwilherm; Ritter, C; Woodward, Patrick M

    2012-04-01

    The structures of the doubly ordered perovskites NaCeMnWO(6) and NaPrMnWO(6), with rock salt ordering of the Mn(2+) and W(6+)B-site cations and layered ordering of the Na(+) and (Ce(3+)/Pr(3+)) A-site cations, have been studied by transmission electron microscopy, electron diffraction, neutron and synchrotron X-ray powder diffraction. Both compounds possess incommensurately modulated crystal structures. In NaCeMnWO(6) the modulation vector (with reference to the ideal ABX(3) perovskite subcell) is q ? 0.067a* (?58.7 Å) and in NaPrMnWO(6)q ? 0.046a* (?85.3 Å). In both compounds the superstructures are primarily the two-dimensional chessboard type, although some crystals of NaCeMnWO(6) were found with one-dimensional stripes. In some crystals of NaPrMnWO(6) there is a coexistence of chessboards and stripes. Modeling of neutron diffraction data shows that octahedral tilting plays an important role in the structural modulation. PMID:22385521

  13. NA49/NA61: results and plans on beam energy and system size scan at the CERN SPS

    E-print Network

    Gazdzicki, M

    2011-01-01

    This paper presents results and plans of the NA49 and NA61/SHINE experiments at the CERN Super Proton Synchrotron concerning the study of relativistic nucleus-nucleus interactions. First, the NA49 evidence for the energy threshold of creating quark-gluon plasma, the onset of deconfinement, in central lead-lead collisions around 30A GeV is reviewed. Then the status of the NA61/SHINE systematic study of properties of the onset of deconfinement is presented. Second, the search for the critical point of strongly interacting matter undertaken by both experiments is discussed. NA49 measured large fluctuations at the top SPS energy, 158A GeV, in collisions of light and medium size nuclei. They seem to indicate that the critical point exists and is located close to baryonic chemical potential of about 250 MeV. The NA61/SHINE beam energy and system size scan started in 2009 will provide evidence for the existence of the critical point or refute the interpretation of the NA49 fluctuation data in terms of the critical p...

  14. Reactions of NaCl with gaseous SO3, SO2, and O2

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.; Stearns, C. A.; Kohl, F. J.

    1984-01-01

    Hot corrosion of gas turbine engine components involves deposits of Na2SO4 which are produced by reactions between NaCl and oxides of sulfur. For the present investigation, NaCl single crystals were exposed at 100 to 850 C to gaseous mixtures of SO3, SO2, and O2. The products formed during this exposure depend, primarily, on the temperatures. The four product films were: NaCl-SO3; Na2S2O7; Na2SO4; and NaCl-Na2SO4. The kinetics of the reactions were measured.

  15. Reactions of NaCl with Gaseous SO3, SO2, and O2

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.; Stearns, C. A.; Kohl, F. J.

    1983-01-01

    Hot corrosion of gas turbine engine components involves deposits of Na2SO4 which are produced by reactions between NaCl and oxides of sulfur. For the present investigation, NaCl single crystals were exposed at 100 to 850 C to gaseous mixtures of SO3, SO2, and O2. The products formed during this exposure depend, primarily, on the temperatures. The four product films were: NaCl-SO3; Na2S2O7; Na2SO4; and NaCl-Na2SO4. The kinetics of the reactions were measured.

  16. Effects of intra- and extracellular H + and Na + concentrations on Na + -H + antiport activity in the lacrimal gland acinar cells

    Microsoft Academic Search

    Yoshitaka Saito; Terutaka Ozawa; Akinori Nishiyama

    1990-01-01

    Kinetic properties of the Na+-H+ antiport in the acinar cells of the isolated, superfused mouse lacrimal gland were studied by measuring intracellular pH (pHi) and Na+ activity (aNai) with the aid of double-barreled H+- and Na+-selective microelectrodes, respectively. Bicarbonate-free solutions were used throughout. Under untreated control conditions, pHi was 7.12±0.01 and aNai was 6.7±0.6 mmol\\/l. The cells were acid-loaded by

  17. O3-type Na(Mn?.??Fe?.??Co?.??Ni?.??)O?: a quaternary layered cathode compound for rechargeable Na ion batteries

    DOE PAGESBeta

    Li, Xi [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Zhou, Yong-Ning [Brookhaven National Laboratory (BNL), Upton, NY (United States); Wu, Di [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Mechanical Engineering; Liu, Lei [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Ceder, Gerbrand [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Materials Science and Engineering; Yang, Xiao-Qing [Brookhaven National Laboratory (BNL), Upton, NY (United States)

    2014-12-01

    We report a new layered Na(Mn?.??Fe?.??Co?.??Ni?.??)O? compound with O3 oxygen stacking. It delivers 180 mAh/g initial discharge capacity and 578 Wh/kg specific energy density with good cycling capability at high cutoff voltage. In situ X-ray diffraction (XRD) shows a reversible structure evolution of O3-P3-O3'-O3'' upon Na de-intercalation. The excellent capacity and cycling performance at high cutoff voltage make it an important model system for studying the general issue of capacity fading in layered Na cathode compounds.

  18. Calculation of spectroscopic constants and radiative parameters for the B 1?- X 1?+ electronic transitions of NaK, NaRb, and NaCs molecules

    NASA Astrophysics Data System (ADS)

    Smirnov, A. D.

    2014-09-01

    The vibrational, rotational, and centrifugal spectroscopic constants and the radiative parameters (the Einstein coefficients, oscillator strengths, Frank-Condon factors, r v'v? centroids, and wavenumbers of rotational lines) of electronic-vibrational-rotational transitions in the systems of bands B 1? - X 1?+ of NaK (0 ? v' ? 14, 0 ? v? ? 52, j = 0, 30, 50, 70, 80, and 100), NaRb (0 ? v' ? 12, 0 ? v? ? 51, j = 0, 20, 30, 50, 70, 90, 100, and 120), and NaCs (0 ? v' ? 10, 0 ? v? ? 44, j = 0, 30, 50, 70, 90, 100, and 120) molecules, as well as the radiative lifetimes of excited electronic states, are calculated. Calculations are performed based on semiempirical potential curves constructed in this work. The calculated spectroscopic constants and the radiative lifetimes are compared with experimental values.

  19. Na+-K+ Pump Regulation and Skeletal Muscle Contractility

    NSDL National Science Digital Library

    MD Torben Clausen (University of Aarhus Department of Physiology)

    2003-10-01

    The present review is written with the specific purpose of analyzing how regulation of the activity and the capacity of the Na+-K+ pumps influences excitability and contractile performance in skeletal muscle.

  20. O, Na, Ba and Eu abundance patterns in open clusters

    E-print Network

    MacLean, B T; Lattanzio, J

    2014-01-01

    Open clusters are historically regarded as single-aged stellar populations representative of star formation within the Galactic disk. Recent literature has questioned this view, based on discrepant Na abundances relative to the field, and concerns about the longevity of bound clusters contributing to a selection bias: perhaps long-lived open clusters are chemically different to the star formation events that contributed to the Galactic disk. We explore a large sample of high resolution Na, O, Ba & Eu abundances from the literature, homogenized as much as reasonable including accounting for NLTE effects, variations in analysis and choice of spectral lines. Compared to a template globular cluster and representative field stars, we find no significant abundance trends, confirming that the process producing the Na-O anti-correlation in globular clusters is not present in open clusters. Furthermore, previously reported Na-enhancement of open clusters is found to be an artefact of NLTE effects, with the open cl...

  1. NaIrO3—A Pentavalent Post-perovskite

    SciTech Connect

    M Bremholm; S Dutton; P Stephens; R Cava

    2011-12-31

    Sodium iridium (V) oxide, NaIrO{sub 3}, was synthesized by a high pressure solid state method and recovered to ambient conditions. It is found to be isostructural with CaIrO{sub 3}, the much-studied structural analog of the high-pressure post-perovskite phase of MgSiO{sub 3}. Among the oxide post-perovskites, NaIrO{sub 3} is the first example with a pentavalent cation. The structure consists of layers of corner- and edge-sharing IrO{sub 6} octahedra separated by layers of NaO{sub 8} bicapped trigonal prisms. NaIrO{sub 3} shows no magnetic ordering and resistivity measurements show non-metallic behavior. The crystal structure, electrical and magnetic properties are discussed and compared to known post-perovskites and pentavalent perovskite metal oxides.

  2. Neutral Phospholipids Stimulate Na,K-ATPase Activity

    PubMed Central

    Haviv, Haim; Habeck, Michael; Kanai, Ryuta; Toyoshima, Chikashi; Karlish, Steven J. D.

    2013-01-01

    Membrane proteins interact with phospholipids either via an annular layer surrounding the transmembrane segments or by specific lipid-protein interactions. Although specifically bound phospholipids are observed in many crystal structures of membrane proteins, their roles are not well understood. Na,K-ATPase is highly dependent on acid phospholipids, especially phosphatidylserine, and previous work on purified detergent-soluble recombinant Na,K-ATPase showed that phosphatidylserine stabilizes and specifically interacts with the protein. Most recently the phosphatidylserine binding site has been located between transmembrane segments of ?TM8–10 and the FXYD protein. This paper describes stimulation of Na,K-ATPase activity of the purified human ?1?1 or ?1?1FXYD1 complexes by neutral phospholipids, phosphatidylcholine, or phosphatidylethanolamine. In the presence of phosphatidylserine, soy phosphatidylcholine increases the Na,K-ATPase turnover rate from 5483 ± 144 to 7552 ± 105 (p < 0.0001). Analysis of ?1?1FXYD1 complexes prepared with native or synthetic phospholipids shows that the stimulatory effect is structurally selective for neutral phospholipids with polyunsaturated fatty acyl chains, especially dilinoleoyl phosphatidylcholine or phosphatidylethanolamine. By contrast to phosphatidylserine, phosphatidylcholine or phosphatidylethanolamine destabilizes the Na,K-ATPase. Structural selectivity for stimulation of Na,K-ATPase activity and destabilization by neutral phospholipids distinguish these effects from the stabilizing effects of phosphatidylserine and imply that the phospholipids bind at distinct sites. A re-examination of electron densities of shark Na,K-ATPase is consistent with two bound phospholipids located between transmembrane segments ?TM8–10 and TMFXYD (site A) and between TM2, -4, -6, -and 9 (site B). Comparison of the phospholipid binding pockets in E2 and E1 conformations suggests a possible mechanism of stimulation of Na,K-ATPase activity by the neutral phospholipid. PMID:23430748

  3. Single Na+ channel currents observed in cultured rat muscle cells

    Microsoft Academic Search

    Frederick J. Sigworth; Erwin Neher

    1980-01-01

    The voltage- and time-dependent conductance of membrane Na+ channels is responsible for the propagation of action potentials in nerve and muscle cells. In voltage-step-clamp experiments on neurone preparations containing 104-107 Na+ channels the membrane conductance shows smooth variations in time, but analysis of fluctuations1,2 and other evidence3 suggest that the underlying single-channel conductance changes are stochastic, rapid transitions between `closed'

  4. An empirical NaKCa geothermometer for natural waters

    USGS Publications Warehouse

    Fournier, R.O.; Truesdell, A.H.

    1973-01-01

    An empirical method of estimating the last temperature of water-rock interaction has been devised. It is based upon molar Na, K and Ca concentrations in natural waters from temperature environments ranging from 4 to 340??C. The data for most geothermal waters cluster near a straight line when plotted as the function log ( Na K) + ?? log [ ??? (Ca) Na] vs reciprocal of absolute temperature, where ?? is either 1 3 or 4 3 depending upon whether the water equilibrated above or below 100??C. For most waters tested, the method gives better results than the Na K methods suggested by other workers. The ratio Na K should not be used to estimate temperature if ??? ( MCa) MNa is greater than 1. The Na K values of such waters generally yield calculated temperatures much higher than the actual temperature at which water interacted with the rock. A comparison of the composition of boiling hot-spring water with that obtained from a nearby well (170??C) in Yellowstone Park shows that continued water-rock reactions may occur during ascent of water even though that ascent is so rapid that little or no heat is lost to the country rock, i.e. the water cools adiabatically. As a result of such continued reaction, waters which dissolve additional Ca as they ascend from the aquifer to the surface will yield estimated aquifer temperatures that are too low. On the other hand, waters initially having enough Ca to deposit calcium carbonate during ascent may yield estimated aquifer temperatures that are too high if aqueous Na and K are prevented from further reaction with country rock owing to armoring by calcite or silica minerals. The Na-K-Ca geothermometer is of particular interest to those prospecting for geothermal energy. The method also may be of use in interpreting compositions of fluid inclusions. ?? 1973.

  5. Coupling mechanism of the oxaloacetate decarboxylase Na(+) pump.

    PubMed

    Dimroth, P; Jockel, P; Schmid, M

    2001-05-01

    The oxaloacetate decarboxylase Na(+) pump consists of subunits alpha, beta and gamma, and contains biotin as the prosthetic group. The peripheral alpha subunit catalyzes the carboxyltransfer from oxaloacetate to the prosthetic biotin group to yield the carboxybiotin enzyme. Subsequently, this is decarboxylated in a Na(+)-dependent reaction by the membrane-bound beta subunit. The decarboxylation is coupled to Na(+) translocation from the cytoplasm into the periplasm, and consumes a periplasmically derived proton. The gamma subunit contains a Zn(2+) metal ion which may be involved in the carboxyltransfer reaction. It is proposed to insert with its N-terminal alpha-helix into the membrane and to form a complex with the alpha subunit with its water-soluble C-terminal domain. The beta subunit consists of nine transmembrane alpha-helices, a segment (IIIa) which inserts from the periplasm into the membrane but does not penetrate it, and connecting hydrophilic loops. The most highly conserved regions of the molecule are segment IIIa and transmembrane helix VIII. Functionally important residues are D203 (segment IIIa), Y229 (helix IV) and N373, G377, S382 and R389 (helix VIII). The polar of these amino acids may constitute a network of ionizable groups which promotes the translocation of Na(+) and the oppositely oriented translocation of H(+) across the membrane. Evidence indicates that two Na(+) ions are bound simultaneously to subunit beta with D203 and S382 acting as binding sites. Sodium ion binding from the cytoplasm to both sites elicits decarboxylation of carboxybiotin possibly with the consumption of the proton extracted from S382 and delivered via Y229 to the carboxylated prosthetic group. A conformational change exposes the bound Na(+) ions toward the periplasm. With H(+) entering from the periplasm, the hydroxyl group of S382 is regenerated, and as a consequence, the Na(+) ions are released into this compartment. After switching back to the original conformation, Na(+) pumping continues. PMID:11248184

  6. NaCa exchange current in mammalian heart cells

    Microsoft Academic Search

    Junko Kimura; Akinori Noma; Hiroshi Irisawa

    1986-01-01

    Electrogenic Na-Ca exchange has been known to act in the cardiac sarcolemma as a major mechanism for extruding Ca ions1-3. Ionic flux measurements in cardiac vesicles have recently suggested that the exchange ratio is probably 3 Na:l Ca (refs 4, 5), although a membrane current generated by such a process has not been isolated. Using the intracellular perfusion technique6,7 combined

  7. Evolution of Na(+) and H(+) bioenergetics in methanogenic archaea.

    PubMed

    Schlegel, Katharina; Müller, Volker

    2013-02-01

    Methanogenic archaea live at the thermodynamic limit of life and use sophisticated mechanisms for ATP synthesis and energy coupling. The group of methanogens without cytochromes use an Na(+) current across the membrane for ATP synthesis, whereas the cytochrome-containing methanogens have additional coupling sites that also translocate protons. The ATP synthase in this group is promiscuous and uses Na(+) and H(+) simultaneously. PMID:23356322

  8. H- survival probability during collisions with Na/Cu(111)

    NASA Astrophysics Data System (ADS)

    Yu, S.; Bahrim, B.; Makarenko, B.; Rabalais, J. W.

    2015-06-01

    The survival probability of the H- ions colliding with a 0.25 ML Na covered Cu(111) surface is studied by both theory and experiment. We find that the survival probability is influenced by the projectile direction on surface. The reason is the different bonding between the Na atoms and their Cu neighbors along different surface directions. A stronger bond leads to a larger survival probability.

  9. Vanillin Reduction NaOH (1.0 M)

    E-print Network

    Taber, Douglass

    Vanillin Reduction H O O Me OH NaBH4 NaOH (1.0 M) O Me OH OH 1) 2) HCl vanillin vanillyl alcohol To a 25 mL round bottomed flask add vanillin (2.0 g), ethanol (4 mL) and a stir bar. The round bottomed flask is then clamped above the magnetic stirrer. Stir vanillin solution until it is homogeneous (5

  10. Molybdenum extraction from molybdenite concentrate in NaCl electrolyte

    Microsoft Academic Search

    Zhan-fang Cao; Hong Zhong; Guang-yi Liu; Yun-ren Qiu; Shuai Wang

    2010-01-01

    The electro-oxidation of molybdenite concentrate in NaCl electrolyte has been investigated. When the liquid–solid ratio is 25, mixing rate, 400rpm, pH=9, room temperature, concentration of NaCl, 4mol\\/L, then the dissolution rate of molybdenite can achieve 99.97% in 240min. With DSA (dimensionally stable anode) as anode, the polarization curves have been investigated. The results show that molybdenite concentrate cannot be electro-oxidated

  11. Accelerated chondrocyte functions on NaOH-treated PLGA scaffolds

    Microsoft Academic Search

    Grace E. Park; Megan A. Pattison; Thomas J. Webster

    2005-01-01

    Compared to conventional poly(lactic-co-glycolic acid) (PLGA), previous studies have shown that NaOH-treated PLGA two-dimensional substrates enhanced functions of osteoblasts (bone-forming cells), vascular and bladder smooth muscle cells, and chondrocytes (cartilage-synthesizing cells). In this same spirit, the purpose of this in vitro study was to fabricate three-dimensional NaOH-treated PLGA scaffolds and determine their efficacy toward articular cartilage applications. To improve functions

  12. Theoretical perspective on the NA62 physics program

    E-print Network

    Christopher Smith

    2010-12-16

    Soon the NA62 experiment will start looking for the rare K+ ---> pi+ nu nu bar decay. In this talk, its theoretical interests, together with those of the neutral rare decays KL ---> pi0 nu nu bar, KL ---> pi0 e+ e-, and KL ---> pi0 mu+ mu-, are briefly reviewed. Then, other possible targets for NA62 are discussed, among which the dominant semileptonic decays, the radiative decays, as well as the lepton-flavor violating decays.

  13. High Capacity Na+/H+ Exchange Activity in Mineralizing Osteoblasts

    PubMed Central

    Liu, Li; Schlesinger, Paul H.; Slack, Nicole M.; Friedman, Peter A.; Blair, Harry C.

    2015-01-01

    Osteoblasts synthesize bone in polarized groups of cells sealed by tight junctions. Large amounts of acid are produced as bone mineral is precipitated. We addressed the mechanism by which cells manage this acid load by measuring intracellular pH (pHi) in non-transformed osteoblasts in response to weak acid or bicarbonate loading. Basal pHi in mineralizing osteoblasts was ?7.3 and decreased by ? 1.4 units upon replacing extracellular Na+ with N-methyl-d-glucamine. Loading with 40 mM acetic or propionic acids, in normal extracellular Na+, caused only mild cytosolic acidification. In contrast, in Na+-free solutions, weak acids reduced pHi dramatically. After Na+ reintroduction, pHi recovered rapidly, in keeping with Na+/H+exchanger (NHE) activity. Sodium-dependent pHi recovery from weak acid loading was inhibited by amiloride with the Ki consistent with NHEs. NHE1 and NHE6 were expressed strongly, and expression was upregulated highly, by mineralization, in human osteoblasts. Antibody labeling of mouse bone showed NHE1 on basolateral surfaces of all osteoblasts. NHE6 occurred on basolateral surfaces of osteoblasts mainly in areas of mineralization. Conversely, elevated HCO3- alkalinized osteoblasts, and pH recovered in medium containing CI-, with or without Na+, in keeping with Na+-independent CI-/HCO3- exchange. The exchanger AE2 also occurred on the basolateral surface of osteoblasts, consistent with CI-/HCO3- exchange for elimination of metabolic carbonate. Overexpression of NHE6 or knockdown of NHE1 in MG63 human osteosarcoma cells confirmed roles of NHE1 and NHE6 in maintaining pHi. We conclude that in mineralizing osteoblasts, slightly basic basal pHi is maintained, and external acid load is dissipated, by high-capacity Na+/H+ exchange via NHE1 and NHE6. PMID:21413028

  14. thin films grown with additional NaF layers

    NASA Astrophysics Data System (ADS)

    Kim, Gee Yeong; Kim, Juran; Jo, William; Son, Dae-Ho; Kim, Dae-Hwan; Kang, Jin-Kyu

    2014-10-01

    CZTS precursors [SLG/Mo (300 nm)/ZnS (460 nm)/SnS (480 nm)/Cu (240 nm)] were deposited by RF/DC sputtering, and then NaF layers (0, 15, and 30 nm) were grown by electron beam evaporation. The precursors were annealed in a furnace with Se metals at 590°C for 20 minutes. The final composition of the CZTSSe thin-films was of Cu/(Zn + Sn) ~ 0.88 and Zn/Sn ~ 1.05, with a metal S/Se ratio estimated at ~0.05. The CZTSSe thin-films have different NaF layer thicknesses in the range from 0 to 30 nm, achieving a ~3% conversion efficiency, and the CZTSSe thin-films contain ~3% of Na. Kelvin probe force microscopy was used to identify the local potential difference that varied according to the thickness of the NaF layer on the CZTSSe thin-films. The potential values at the grain boundaries were observed to increase as the NaF thickness increased. Moreover, the ratio of the positively charged GBs in the CZTSSe thin-films with an NaF layer was higher than that of pure CZTSSe thin-films. A positively charged potential was observed around the grain boundaries of the CZTSSe thin-films, which is a beneficial characteristic that can improve the performance of a device.

  15. [Na] and [K] dependence of the Na\\/K pump current-voltage relationship in guinea pig ventricular myocytes

    Microsoft Academic Search

    MASAKAZU NAKAO; DAVID C. GADSBY

    1989-01-01

    Na\\/K pump current was determined between - 140 and +60 mV as steady-state, strophanthidin-sensitive, whole-cell current in guinea pig ventricular myocytes, voltage-clamped and internally dialyzed via wide-tipped pipettes. Solu- tions were designed to minimize all other components of membrane current. A device for exchanging the solution inside the pipette permitted investigation of Na\\/K pump current-voltage (I-V) relationships at several levels

  16. Adsorption of Zn 2+ ions onto NaA and NaX zeolites: Kinetic, equilibrium and thermodynamic studies

    Microsoft Academic Search

    D. Nibou; H. Mekatel; S. Amokrane; M. Barkat; M. Trari

    2010-01-01

    The adsorption of Zn2+ onto NaA and NaX zeolites was investigated. The samples were synthesized according to a hydrothermal crystallization using aluminium isopropoxide (Al[OCH(CH3)2]3) as a new alumina source. The effects of pH, initial concentration, solid\\/liquid ratio and temperature were studied in batch experiments. The Freundlich and the Langmuir models were applied and the adsorption equilibrium followed Langmuir adsorption isotherm.

  17. Copper toxicity in cultured human skeletal muscle cells: the involvement of Na + \\/K + ATPase and the Na + \\/Ca 2+ -exchanger

    Microsoft Academic Search

    Ad A. G. M. Benders; Jie Li; Robert A. C. Lock; René J. M. Bindels; Sjoerd E. Wendelaar Bonga; Jacques H. Veerkamp

    1994-01-01

    Copper (Cu2+) intoxication has been shown to induce pathological changes in various tissues. The mechanism underlying Cu2+ toxicity is still unclear. It has been suggested that the Na+\\/K+-ATPase and\\/or a change of the membrane permeability may be involved. In this study we examined the effects of Cu2+ on the Na+ and Ca2+ homeostasis of cultured human skeletal muscle cells using

  18. Biodiesel production from rubber seed oil using poly (sodium acrylate) supporting NaOH as a water-resistant catalyst

    Microsoft Academic Search

    Ru Yang; Mengxing Su; Jianchun Zhang; Fuqiang Jin; Chunhong Zha; Min Li; Xinmin Hao

    2011-01-01

    Poly (sodium acrylate) supporting NaOH (NaOH\\/NaPAA) was prepared by in situ polymerization of aqueous solution of acrylic acid with an over-neutralization by adding excess of NaOH. NaOH\\/NaPAA presented a promising selectivity for water absorbency and good water retention with negligible swelling capacity in the organic solvents of methanol, glycerol, rubber seed oil methyl esters, and rubber seed oil. NaOH\\/NaPAA catalysts

  19. NaCl Taste Thresholds in 13 Inbred Mouse Strains

    PubMed Central

    Ishiwatari, Yutaka

    2012-01-01

    Molecular mechanisms of salty taste in mammals are not completely understood. We use genetic approaches to study these mechanisms. Previously, we developed a high-throughput procedure to measure NaCl taste thresholds, which involves conditioning mice to avoid LiCl and then examining avoidance of NaCl solutions presented in 48-h 2-bottle preference tests. Using this procedure, we measured NaCl taste thresholds of mice from 13 genealogically divergent inbred stains: 129P3/J, A/J, BALB/cByJ, C3H/HeJ, C57BL/6ByJ, C57BL/6J, CBA/J, CE/J, DBA/2J, FVB/NJ, NZB/BlNJ, PWK/PhJ, and SJL/J. We found substantial strain variation in NaCl taste thresholds: mice from the A/J and 129P3/J strains had high thresholds (were less sensitive), whereas mice from the BALB/cByJ, C57BL/6J, C57BL/6ByJ, CE/J, DBA/2J, NZB/BINJ, and SJL/J had low thresholds (were more sensitive). NaCl taste thresholds measured in this study did not significantly correlate with NaCl preferences or amiloride sensitivity of chorda tympani nerve responses to NaCl determined in the same strains in other studies. To examine whether strain differences in NaCl taste thresholds could have been affected by variation in learning ability or sensitivity to toxic effects of LiCl, we used the same method to measure citric acid taste thresholds in 4 inbred strains with large differences in NaCl taste thresholds but similar acid sensitivity in preference tests (129P3/J, A/J, C57BL/6J, and DBA/2J). Citric acid taste thresholds were similar in these 4 strains. This suggests that our technique measures taste quality–specific thresholds that are likely to represent differences in peripheral taste responsiveness. The strain differences in NaCl taste sensitivity found in this study provide a basis for genetic analysis of this phenotype. PMID:22293936

  20. Drift tube measurements on Na+ ions and clusters using the 24mNa+ tracer

    NASA Astrophysics Data System (ADS)

    Kasuya, A.; Abmayr, B.; Ohtsuki, T.; Masumoto, K.; Kotajima, H.; Huenges, E.; Morinaga, H.

    1997-06-01

    Mobilities of sodium ions and their clusters in different gases have been measured by gamma-ray spectrometry using the 20 ms isomeric state of 24Na as tracer. This isomer is obtained through the ?-decay of 24Ne, which was produced by bombarding 22Ne with the 7 MeV triton beam of a cyclotron. This new technique of measurement allows us to determine the mobility of sodium ions in non-reacting gases of a pressure above 1 mbar. Measurements have been carried out in gases of pressures ranging from 6 mbar to 1000 mbar under an electric field up to 250 V/cm at room temperature. The measured mobility of 24Na+ in pure neon gas at 1000 mbar was determined to be 3.2 cm2/Vs. This value is lower than the zero field mobility of about 8.5 cm2/Vs measured by Tyndall and Akridge. A small amount of polar molecules such as water or ethanol introduced into the drift tube causes their clustering with the sodium ions through monopole-dipole interaction, resulting in a strong decrease in the mobility. This clustering effect has been studied for various combinations of polar molecules and inert gases. The usable pressure range from 1 mbar to high pressures in the range of some hundred bars is interesting because most other methods for cluster studies cannot be done at such high pressures. With this method it is possible to measure the mobility change of sodium ions towards the condensation point and eventually even towards the critical point.

  1. The dynamic relationships between the three events that release individual Na? ions from the Na?/K?-ATPase.

    PubMed

    Gadsby, David C; Bezanilla, Francisco; Rakowski, Robert F; De Weer, Paul; Holmgren, Miguel

    2012-01-01

    Na(+)/K(+) pumps move net charge through the cell membrane by mediating unequal exchange of intracellular Na(+) and extracellular K(+). Most charge moves during transitions that release Na(+) to the cell exterior. When pumps are constrained to bind and release only Na(+), a membrane voltage-step redistributes pumps among conformations with zero, one, two or three bound Na(+), thereby transiently generating current. By applying rapid voltage steps to squid giant axons, we previously identified three components in such transient currents, with distinct relaxation speeds: fast (which nearly parallels the voltage-jump time course), medium speed (?(m)=0.2-0.5?ms) and slow (?(s)=1-10?ms). Here we show that these three components are tightly correlated, both in their magnitudes and in the time courses of their changes. The correlations reveal the dynamics of the conformational rearrangements that release three Na(+) to the exterior (or sequester them into their binding sites) one at a time, in an obligatorily sequential manner. PMID:22334072

  2. Upconversion improvement by the reduction of Na?-vacancies in Mn²? doped hexagonal NaYbF?:Er³? nanoparticles.

    PubMed

    Tian, Dongping; Gao, Dangli; Chong, Bo; Liu, Xuanzuo

    2015-03-01

    Hexagonal-phase NaYbF4:Er(3+) upconversion nanoparticles (UCNPs) have been synthesized via a co-precipitation method in high-boiling-point solvents, and remarkably enhanced upconversion luminescence, particularly in red emission bands (650-670 nm) in NaYbF4:Er(3+) UCNPs, has been achieved by Mn(2+) doping. The underlying reason for luminescence enhancement by Mn(2+) doping is explored by a series of controlled experiments, and a mechanism of enhancement based on the decrease of Na(+)-vacancies and organic adsorption is proposed. The Mn(2+) substitution disturbs the equilibrium of the charge and crystal lattice in the hexagonal-phase NaYbF4:Er(3+) UCNPs, which makes the Na(+)-vacancies that quenched luminescence become filled with Na(+) or Mn(2+) to offset the imbalance of the charge and electron cloud distortion. In addition, the Mn(2+) doping at the surface of UCNPs could reduce the organic adsorption on the surface of the UCNPs by an extra F(-) ion on the grain surface resulting in luminescence enhancement. Therefore, the Mn(2+)-doping approach provides a facile strategy for improvement of luminescence, which will impact on the field of bioimaging based on UCNP nanoprobes. PMID:25622805

  3. Effect of Na doping on flux pinning of YBa 1.9Na 0.1Cu 3O 7- ?

    NASA Astrophysics Data System (ADS)

    Ding, S. Y.; Leng, X.; Qiu, L.; Wang, Z. H.; Liu, Y.; Zhang, H.

    2003-03-01

    We have prepared Na-doped YBa 2Cu 3O y (YBa 1.9Na 0.1Cu 3O y+40 mol% Y211) (YBNCO) and Na-free YBa 2Cu 3O y (YBCO) samples by the melt-textured growth method to study the effect of doped Na ion on flux pinning. The ac susceptibility curves as well as the hysteresis loops were measured for the samples. Then the effective pinning energy ( U( T, Hdc, J)), irreversibility line ( Hirr( T)) and critical current density ( jc( Hdc)) were determined, where T, Hdc and J are temperature, dc magnetic field and current density, respectively. We found that, with Na doping, the Hirr( T) line shifted to lower temperatures while the Jc( Hdc) and U( T, Hdc, J) became smaller. Hence Na ions play a negative role in the flux pinning of YBCO. The appearance of the second peak in the Jc( Hdc) curves and the enhancement of anisotropy in YBNCO further support this finding.

  4. Improved measurements of Na+ fluxes in plants using calixarene-based microelectrodes.

    PubMed

    Jayakannan, Maheswari; Babourina, Olga; Rengel, Zed

    2011-07-01

    Ion-selective microelectrodes are a powerful tool in studying adaptive responses of plant cells and tissues to various abiotic stresses. However, application of this technique in Na(+) flux measurements was limited due to poor selectivity for Na(+) ions of commercially available Na(+) cocktails. Often, these cocktails cannot discriminate between Na(+) and other interfering ions such as K(+) and Ca(2+), leading to inaccurate measurements of Na(+) concentration and, consequently, inaccurate Na(+) flux calculations. To overcome this problem, three Na(+)-selective cocktail mixtures were prepared using tetramethoxyethyl ester derivative of p-t-butyl calix[4]arene. These cocktail mixtures were compared with commercially available ETH 227-based Na(+) cocktail for selectivity for Na(+) ions over other ions (particularly K(+) and Ca(2+)). Among the three calixarene-based Na(+) cocktails tested, cocktail 2 [in % w/w: Na(+) ionophore (4-tert-butylcalix[4]arene-tetra acetic acid tetraethyl ester) 3.5, the plasticizer (2-nitrophenyl octyl ether) 95.9 and lipophilic anion (potassium tetrakis (4-chlorophenyl) borate) 0.6] showed the best selectivity for Na(+) ions over K(+) and Ca(2+) ions and was highly stable over time (up to 10h). Na(+) flux measurements under a wide range of NaCl concentrations (25-150 mM) using Na(+) cocktail 2 established a clear dose-response relationship between severity of salt stress and magnitude of Na(+) influx at the distal elongation and mature zones of Arabidopsis thaliana roots. Furthermore, Na(+) cocktail 2 was compared with commercially available ETH 227-based Na(+) cocktail by measuring Na(+) fluxes at the two Arabidopsis root zones in response to 100mM NaCl treatment. With calixarene-based Na(+) cocktail 2, a large decreasing Na(+) influx (0-15 min) followed by small Na(+) influx (15-45 min) was measured, whereas with ETH-based Na(+) cocktail Na(+) influx was short-lived (1-3 min) and was followed by Na(+) efflux (3-45 min) that might have been due to K(+) and Ca(2+) efflux measured together with Na(+) influx. In conclusion, Na(+)-selective calixarene-based microelectrodes have excellent potential to be used in real-time Na(+) flux measurements in plants. PMID:21256620

  5. A sodium calcium arsenate, NaCa(AsO4)

    PubMed Central

    Lin, Jinru; Sun, Wei; Mi, Jin-Xiao; Pan, Yuanming

    2011-01-01

    The title compound, NaCa(AsO4), was synthesized using a hydro­thermal method at 633–643?K. It has a dense structure composed of alternating layers of distorted [CaO6] octa­hedra and layers of [AsO4] tetra­hedra and distorted [NaO6] octa­hedra, stacked along the a axis. The As, Ca and two O atoms lie on the mirror plane at y = 1/4 (i.e. 4c), while the Na atom lies on an inversion centre (1/2, 1/2, 0) (i.e. 4b). Each distorted [CaO6] octa­hedron shares four equatorial common O vertices with four neighboring octa­hedra, forming a layer parallel to (100), whereas each distorted [NaO6] octa­hedron shares two opposite edges with two neighboring ones, forming a chain running along [010]. Each isolated [AsO4] tetra­hedron shares two edges with two different [NaO6] octa­hedra in one [NaO6] chain and a vertex with another chain. Simultaneously the above [AsO4] tetra­hedron located in a four-membered [CaO6] ring shares one edge of its base facet with one [CaO6] octa­hedron and three corners with three other [CaO6] octa­hedra of one [CaO6] layer, and the remaining apex is shared with another [CaO6] layer. [NaO6] octa­hedra and [CaO6] octa­hedra are linked to each other by sharing edges and vertices. PMID:22199467

  6. The Expression Pattern of the Na(+) Sensor, Na(X) in the Hydromineral Homeostatic Network: A Comparative Study between the Rat and Mouse.

    PubMed

    Nehmé, Benjamin; Henry, Mélaine; Mouginot, Didier; Drolet, Guy

    2012-01-01

    The Scn7a gene encodes for the specific sodium channel Na(X), which is considered a primary determinant of sodium sensing in the brain. Only partial data exist describing the Na(X) distribution pattern and the cell types that express Na(X) in both the rat and mouse brain. To generate a global view of the sodium detection mechanisms in the two rodent brains, we combined Na(X) immunofluorescence with fluorescent cell markers to map and identify the Na(X)-expressing cell populations throughout the network involved in hydromineral homeostasis. Here, we designed an anti-Na(X) antibody targeting the interdomain 2-3 region of the Na(X) channel's ?-subunit. In both the rat and mouse, Na(X) immunostaining was colocalized with vimentin positive cells in the median eminence and with magnocellular neurons immunopositive for neurophysin associated with oxytocin or vasopressin in both the supraoptic and paraventricular nuclei. Na(X) immunostaining was also detected in neurons of the area postrema. In addition to this common Na(X) expression pattern, several differences in Na(X) immunostaining for certain structures and cell types were found between the rat and mouse. Na(X) was present in both NeuN and vimentin positive cells in the subfornical organ and the vascular organ of the lamina terminalis of the rat whereas Na(X) was only colocalized with vimentin positive cells in the mouse circumventricular organs. In addition, Na(X) immunostaining was specifically observed in NeuN immunopositive cells in the median preoptic nucleus of the rat. Overall, this study characterized the Na(X)-expressing cell types in the network controlling hydromineral homeostasis of the rat and mouse. Na(X) expression pattern was clearly different in the nuclei of the lamina terminalis of the rat and mouse, indicating that the mechanisms involved in systemic and central Na(+) sensing are specific to each rodent species. PMID:22833716

  7. Fiscalizao e Controle: O Poder Legislativo na Argentina e no Brasil Contemporneos

    E-print Network

    Paris-Sud XI, Université de

    1 Fiscalização e Controle: O Poder Legislativo na Argentina e no Brasil Contemporâneos Charles na Argentina e no Brasil Contemporâneos "La société a le droit de demander compte à tout agent public concentrar-se na análise das novas instituições de controle externo no Brasil e na Argentina, de acordo com o

  8. Na7Mg13Nd(PO4)12

    PubMed Central

    Jerbi, Hasna; Hidouri, Mourad; Mongi, Ben Amara

    2012-01-01

    Investigations of the quasi-ternary system Na3PO4–Mg3(PO4)2–NdPO4 allowed us to obtain the new phosphate hepta­sodium trideca­magnesium neodymium dodeca­kis­phosphate, Na7Mg13Nd(PO4)12, by applying a flux method. The crystal structure is isotypic with that of the previously reported Na7Mg13 Ln(PO4)12 (Ln = Eu, La) compounds. It consists of a complex three-dimensional framework built up from an NdO8 polyhedron (m symmetry), an MO6 octa­hedron statistically occupied by M = Mg and Na, and eight MgOx (x = 5, 6) polyhedra (four with site symmetry m), linked either directely by sharing corners, edges and faces, or by one of the eight unique PO4 tetra­hedra through common corners. Two of the PO4 tetra­hedra are statisticaly disordered over a mirror plane. The whole structure can be described as resutling from an assembly of two types of structural units, viz [Mg4 MP4O22]? 2 layers extending parallel to (100) and stacked along [100], and [Mg4NdP4O36]? 1 undulating chains running along the [010] direction. The six different Na+ cations (five with site symmetry m and one with 0.5 occupancy) are situated in six distinct cavities delimited by the framework. The structure was refined from data of a racemic twin. PMID:22719275

  9. Magnetism in Na-filled Fe-based skutterudites

    PubMed Central

    Xing, Guangzong; Fan, Xiaofeng; Zheng, Weitao; Ma, Yanming; Shi, Hongliang; Singh, David J.

    2015-01-01

    The interplay of superconductivity and magnetism is a subject of ongoing interest, stimulated most recently by the discovery of Fe-based superconductivity and the recognition that spin-fluctuations near a magnetic quantum critical point may provide an explanation for the superconductivity and the order parameter. Here we investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe4Sb12 is a known ferromagnet near a quantum critical point. We find a ferromagnetic metallic state for this compound driven by a Stoner type instability, consistent with prior work. In accord with prior work, the magnetization is overestimated, as expected for a material near an itinerant ferromagnetic quantum critical point. NaFe4P12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe4Sb12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe4As12 shows intermediate behavior. We also present results for skutterudite FeSb3, which is a metastable phase that has been reported in thin film form. PMID:26027504

  10. Magnetism in Na-filled Fe-based skutterudites.

    PubMed

    Xing, Guangzong; Fan, Xiaofeng; Zheng, Weitao; Ma, Yanming; Shi, Hongliang; Singh, David J

    2015-01-01

    The interplay of superconductivity and magnetism is a subject of ongoing interest, stimulated most recently by the discovery of Fe-based superconductivity and the recognition that spin-fluctuations near a magnetic quantum critical point may provide an explanation for the superconductivity and the order parameter. Here we investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe4Sb12 is a known ferromagnet near a quantum critical point. We find a ferromagnetic metallic state for this compound driven by a Stoner type instability, consistent with prior work. In accord with prior work, the magnetization is overestimated, as expected for a material near an itinerant ferromagnetic quantum critical point. NaFe4P12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe4Sb12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe4As12 shows intermediate behavior. We also present results for skutterudite FeSb3, which is a metastable phase that has been reported in thin film form. PMID:26027504

  11. Adenosine, type 1 receptors: role in proximal tubule Na+ reabsorption

    PubMed Central

    Welch, William J

    2015-01-01

    Adenosine type 1 receptor (A1-AR) antagonists induce diuresis and natriuresis in experimental animals and humans. Much of this effect is due to inhibition of A1-ARs in the proximal tubule, which is responsible for 60–70% of the reabsorption of filtered Na+ and fluid. Intratubular application of receptor antagonists indicates that A1-AR mediates a portion of Na+ uptake in PT and PT cells, via multiple transport systems, including Na+/H+ exchanger-3 (NHE3), Na+/PO4? co-transporter and Na+-dependent glucose transporter, SGLT. Renal microperfusion and recollection studies have shown that fluid reabsorption is reduced by A1-AR antagonists and is lower in A1-AR KO mice., compared to WT mice. Absolute proximal reabsorption (APR) measured by free-flow micropuncture is equivocal, with studies that show either lower APR or similar APR in A1-AR KO mice, compared to WT mice. Inhibition of A1-ARs lowers elevated blood pressure in models of salt-sensitive hypertension, partially due to their effects in the proximal tubule. PMID:25345761

  12. Ouabain Binding Site in a Functioning Na+/K+ ATPase*

    PubMed Central

    Sandtner, Walter; Egwolf, Bernhard; Khalili-Araghi, Fatemeh; Sánchez-Rodríguez, Jorge E.; Roux, Benoit; Bezanilla, Francisco; Holmgren, Miguel

    2011-01-01

    The Na+/K+ ATPase is an almost ubiquitous integral membrane protein within the animal kingdom. It is also the selective target for cardiotonic derivatives, widely prescribed inhibitors for patients with heart failure. Functional studies revealed that ouabain-sensitive residues distributed widely throughout the primary sequence of the protein. Recently, structural work has brought some consensus to the functional observations. Here, we use a spectroscopic approach to estimate distances between a fluorescent ouabain and a lanthanide binding tag (LBT), which was introduced at five different positions in the Na+/K+ ATPase sequence. These five normally functional LBT-Na+/K+ ATPase constructs were expressed in the cell membrane of Xenopus laevis oocytes, operating under physiological internal and external ion conditions. The spectroscopic data suggest two mutually exclusive distances between the LBT and the fluorescent ouabain. From the estimated distances and using homology models of the LBT-Na+/K+ ATPase constructs, approximate ouabain positions could be determined. Our results suggest that ouabain binds at two sites along the ion permeation pathway of the Na+/K+ ATPase. The external site (low apparent affinity) occupies the same region as previous structural findings. The high apparent affinity site is, however, slightly deeper toward the intracellular end of the protein. Interestingly, in both cases the lactone ring faces outward. We propose a sequential ouabain binding mechanism that is consistent with all functional and structural studies. PMID:21911500

  13. Electronic structure and molecular dynamics of Na2Li

    NASA Astrophysics Data System (ADS)

    Malcolm, Nathaniel O. J.; McDouall, Joseph J. W.

    Following the first report (Mile, B., Sillman, P. D., Yacob, A. R. and Howard, J. A., 1996, J. chem. Soc. Dalton Trans , 653) of the EPR spectrum of the mixed alkali-metal trimer Na2Li a detailed study has been made of the electronic structure and structural dynamics of this species. Two isomeric forms have been found: one of the type, Na-Li-Na, of C , symmetry and another, Li-Na-Na, of C symmetry. Also, there are two linear saddle points which correspond to 'inversion' transition structures, and a saddle point of C symmetry which connects the two minima. A molecular dynamics investigation of these species shows that, at the temperature of the reported experiments (170 K), the C minimum is not 'static', but undergoes quite rapid inversion. At higher temperatures the C minimum converts to the C form, but by a mechanism very different from that suggested by minimum energy path considerations. 2 2v s s 2v 2v s

  14. Effects of Osmoprotectants upon NaCl Stress in Rice.

    PubMed Central

    Garcia, A. B.; Engler, JdA.; Iyer, S.; Gerats, T.; Van Montagu, M.; Caplan, A. B.

    1997-01-01

    Plants accumulate a number of osmoprotective substances in response to NaCl stress, one of them being proline (Pro). While characterizing some of the changes in solute accumulation in NaCl-stressed rice (Oryza sativa L.), we identified several other potential osmoprotectants. One such substance, trehalose, begins to accumulate in small amounts in roots after 3 d. We performed a series of experiments to compare the effects of Pro and trehalose on ion accumulation to determine whether the two chemicals protect the same physiological processes. We found that Pro either has no effect or, in some cases, exasperates the effect of NaCl on growth inhibition, chlorophyll loss, and induction of a highly sensitive marker for plant stress, the osmotically regulated salT gene. By contrast, low to moderate concentrations of trehalose reduce Na+ accumulation, salT expression, and growth inhibition. Somewhat higher concentrations (10 mM) prevent NaCl-induced loss of chlorophyll in blades, preserve root integrity, and enhance growth. The results of this study indicate that during osmotic stress trehalose or carbohydrates might be more important for rice than Pro. PMID:12223797

  15. NaI detector neutron activation spectra for PGNAA applications

    PubMed

    Gardner; El; Zheng; Hayden; Mayo

    2000-10-01

    When NaI detectors are used in prompt gamma-ray neutron activation analysis devices, they are activated by neutrons that penetrate the detector. While thermal neutron filters like boron or lithium can be used to reduce this activation, it can never be completely eliminated by this approach since high energy neutrons can penetrate the detector and thermalize inside it. This activation results in the emission of prompt gamma rays from both the I and Na and the production of the radioisotopes 128I and 24Na that subsequently decay and emit their characteristic beta particles and gamma rays. The resulting three spectra represent a background for this measurement. An experimental method for obtaining these three spectra is described and results are reported for 2" x 2", 5" x 5", 6" x 6", and 1" x 6" NaI detectors using the thermal neutron beam of the NCSU PULSTAR nuclear reactor. In addition, Monte Carlo simulation programs have been developed and used for simulating these spectra. Good results have been obtained by the Monte Carlo method for the two radioisotope spectra, and it is anticipated that good results will also be obtained for the prompt gamma-ray spectrum when the I and Na coincidence schemes are known. PMID:11003483

  16. High-NA HPCS optical fibers for medical diagnosis and treatment

    NASA Astrophysics Data System (ADS)

    Skutnik, Bolesh J.

    2010-02-01

    Hard Plastic Clad Silica (HPCS) optical fibers with pure silica cores have been developed which are robust and have NA(Numerical Aperture)>0.50. Improved clad only HPCS fibers have been produced for both new 'standard' and 'high' NA versions. Based on new cladding formulations, the 'standard' NA fiber has an NA of 0.41, while the new ultrahigh NA fiber has an NA of 0.54. Mechanical strength and preliminary fatigue data are presented along with spectral characterization data. For the first time significant results were obtained for clad only high NA fibers, The fibers are useful for diagnostic and surgical applications. Short to medium length time to failure results, indicate that the static fatigue parameters of the new high numerical aperture (NA) optical fibers are at least as good as those for former standard NA (0.37) HPCS fibers, which is an advance from previous results on the older formulation high NA fibers.

  17. The Na(+) transporter, TaHKT1;5-D, limits shoot Na(+) accumulation in bread wheat.

    PubMed

    Byrt, Caitlin Siobhan; Xu, Bo; Krishnan, Mahima; Lightfoot, Damien James; Athman, Asmini; Jacobs, Andrew Keith; Watson-Haigh, Nathan S; Plett, Darren; Munns, Rana; Tester, Mark; Gilliham, Matthew

    2014-11-01

    Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K(+) /Na(+) ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL. Limited recombination has been observed at this locus making it difficult to map genetically and identify the causal gene. Here, we decipher the function of TaHKT1;5-D, a candidate gene underlying the Kna1 locus. Transport studies using the heterologous expression systems Saccharomyces cerevisiae and Xenopus laevis oocytes indicated that TaHKT1;5-D is a Na(+) -selective transporter. Transient expression in Arabidopsis thaliana mesophyll protoplasts and in situ polymerase chain reaction indicated that TaHKT1;5-D is localised on the plasma membrane in the wheat root stele. RNA interference-induced silencing decreased the expression of TaHKT1;5-D in transgenic bread wheat lines which led to an increase in the Na(+) concentration in the leaves. This indicates that TaHKT1;5-D retrieves Na(+) from the xylem vessels in the root and has an important role in restricting the transport of Na(+) from the root to the leaves in bread wheat. Thus, TaHKT1;5-D confers the essential salinity tolerance mechanism in bread wheat associated with the Kna1 locus via shoot Na(+) exclusion and is critical in maintaining a high K(+) /Na(+) ratio in the leaves. These findings show there is potential to increase the salinity tolerance of bread wheat by manipulation of HKT1;5 genes. PMID:25158883

  18. Cytoplasmic Na+-dependent modulation of mitochondrial Ca2+ via electrogenic mitochondrial Na+–Ca2+ exchange

    PubMed Central

    Kim, Bongju; Matsuoka, Satoshi

    2008-01-01

    To clarify the role of mitochondrial Na+–Ca2+ exchange (NCXmito) in regulating mitochondrial Ca2+ (Ca2+mito) concentration at intact and depolarized mitochondrial membrane potential (??mito), we measured Ca2+mito and ??mito using fluorescence probes Rhod-2 and TMRE, respectively, in the permeabilized rat ventricular cells. Applying 300 nm cytoplasmic Ca2+ (Ca2+c) increased Ca2+mito and this increase was attenuated by cytoplasmic Na+ (Na+c) with an IC50 of 2.4 mm. To the contrary, when ??mito was depolarized by FCCP, a mitochondrial uncoupler, Na+c enhanced the Ca2+c-induced increase in Ca2+mito with an EC50 of about 4 mm. This increase was not significantly affected by ruthenium red or cyclosporin A. The inhibition of NCXmito by CGP-37157 further increased Ca2+mito when ??mito was intact, while it suppressed the Ca2+mito increase when ??mito was depolarized, suggesting that ??mito depolarization changed the exchange mode from forward to reverse. Furthermore, ??mito depolarization significantly reduced the Ca2+mito decrease via forward mode, and augmented the Ca2+mito increase via reverse mode. When the respiratory chain was attenuated, the induction of the reverse mode of NCXmito hyperpolarized ??mito, while ??mito depolarized upon inducing the forward mode of NCXmito. Both changes in ??mito were remarkably inhibited by CGP-37157. The above experimental data indicated that NCXmito is voltage dependent and electrogenic. This notion was supported theoretically by computer simulation studies with an NCXmito model constructed based on present and previous studies, presuming a consecutive and electrogenic Na+–Ca2+ exchange and a depolarization-induced increase in Na+ flux. It is concluded that Ca2+mito concentration is dynamically modulated by Na+c and ??mito via electrogenic NCXmito. PMID:18218682

  19. Effects of K+-deficient diets with and without NaCl supplementation on Na+, K+, and H2O transporters' abundance along the nephron.

    PubMed

    Nguyen, Mien T X; Yang, Li E; Fletcher, Nicholas K; Lee, Donna H; Kocinsky, Hetal; Bachmann, Sebastian; Delpire, Eric; McDonough, Alicia A

    2012-07-01

    Dietary potassium (K(+)) restriction and hypokalemia have been reported to change the abundance of most renal Na(+) and K(+) transporters and aquaporin-2 isoform, but results have not been consistent. The aim of this study was to reexamine Na(+), K(+) and H(2)O transporters' pool size regulation in response to removing K(+) from a diet containing 0.74% NaCl, as well as from a diet containing 2% NaCl (as found in American diets) to blunt reducing total diet electrolytes. Sprague-Dawley rats (n = 5-6) were fed for 6 days with one of these diets: 2% KCl, 0.74% NaCl (2K1Na, control chow) compared with 0.03% KCl, 0.74% NaCl (0K1Na); or 2% KCl, 2%NaCl (2K2Na) compared with 0.03% KCl, 2% NaCl (0K2Na, Na(+) replete). In both 0K1Na and 0K2Na there were significant decreases in: 1) plasma [K(+)] (<2.5 mM); 2) urinary K(+) excretion (<5% of control); 3) urine osmolality and plasma [aldosterone], as well as 4) an increase in urine volume and medullary hypertrophy. The 0K2Na group had the lowest [aldosterone] (172.0 ± 17.4 pg/ml) and lower blood pressure (93.2 ± 4.9 vs. 112.0 ± 3.1 mmHg in 2K2Na). Transporter pool size regulation was determined by quantitative immunoblotting of renal cortex and medulla homogenates. The only differences measured in both 0K1Na and 0K2Na groups were a 20-30% decrease in cortical ?-ENaC, 30-40% increases in kidney-specific Ste20/SPS1-related proline/alanine-rich kinase, and a 40% increase in medullary sodium pump abundance. The following proteins were not significantly changed in both the 0 K groups: Na(+)/H(+) exchanger isoform 3; Na(+)-K(+)-Cl(-) cotransporter; Na(+)-Cl(-) cotransporter, oxidative stress response kinase-1; renal outer medullary K(+) channel; autosomal recessive hypercholesterolemia; c-Src, aquaporin 2 isoform; or renin. Thus, despite profound hypokalemia and renal K(+) conservation, we did not confirm many of the changes that were previously reported. We predict that changes in transporter distribution and activity are likely more important for conserving K(+) than changes in total abundance. PMID:22496411

  20. EDITORIAL: TaCoNa-Photonics 2008 TaCoNa-Photonics 2008

    NASA Astrophysics Data System (ADS)

    Chigrin, Dmitry N.; Busch, Kurt; Lavrinenko, Andrei V.

    2009-11-01

    This special section on theoretical and computational nano-photonics features papers presented at the first International Workshop on Theoretical and Computational Nano-Photonics (TaCoNa-Photonics 2008) held in Bad Honnef, Germany, 3-5 December 2008. The workshop covered a broad range of topics related to current developments and achievements in this interdisciplinary area of research. Since the late 1960s, the word `photonics' has been understood as the science of generating, controlling, and detecting light. Nowadays, a routine fabrication of complex structures with micro- and nano-scale dimensions opens up many new and exciting possibilities in photonics. The science of generating, routing and detecting light in micro- and nano-structured matter, `nano-photonics', is becoming more important both in research and technology and offers many promising applications. The inherently sub-wavelength character of the structures that nano-photonics deals with challenges modern theoretical and computational physics and engineering with many nontrivial questions: Up to what length-scale can one use a macroscopic phenomenological description of matter? Where is the interface between the classical and quantum description of light in nano-scale structures? How can one combine different physical systems, different time- and length-scales in a single computational model? How can one engineer nano-structured materials in order to achieve the desired optical properties for particular applications? Any attempt at answering these kinds of questions is impossible without the joint efforts of physicists, engineers, applied mathematicians and programmers. This is the reason why the major goal of the TaCoNa-Photonics workshops is to provide a forum where theoreticians and specialists in numerical methods from all branches of physics, engineering sciences and mathematics can compare their results, report on novel results and breakthroughs, and discuss new challenges ahead. In order to intensify theoretical discussions and to put them on `solid' ground it was decided to invite world-leading experts in experimental photonics for plenary talks. Over three days, the workshop has brought together more than 70 specialists in theoretical and computational nano-photonics. The workshop took place in the historical `Physikzentrum Bad Honnef', whose unique atmosphere supported a multitude of highly interesting debates and discussions that often lasted until midnight and beyond. Different theoretical and numerical aspects of light generation, control and detection in general inhomogeneous media, photonic crystals, plasmonic structures, metamaterials and integrated optical systems were covered in 15 invited talks and 52 contributed oral and posters presentations. The plenary talks were given by Professor M Wegener (metamaterials) and Professor W Barnes (plasmonics). This special section is a cross-sectional selection of papers which were submitted by the authors of invited and contributed oral presentations. It also includes two papers of the winners of the Best Poster Awards. We hope that these papers will enhance the interest of the scientific community regarding nano-photonics in general and regarding the TaCoNa-Photonics workshop series in particular. It is our distinct pleasure to acknowledge the generous financial support of our sponsors: Karlsruhe School of Optics & Photonics (KSOP) (Germany), U.S. Army International Technology Center-Atlantic, Research Division (USA), and the Office of Naval Research Global (USA). Without the organizational assistance from the International Department of the Universität Karlsruhe GmbH (Germany) this event would simply have been impossible.

  1. Functional evidence for involvement of bumetanide-sensitive Na +K +2Cl ? cotransport in the hepatoportal Na + receptor of the Sprague–Dawley rat

    Microsoft Academic Search

    Hironobu Morita; Nobuhiro Fujiki; Masanobu Hagiike; Osamu Yamaguchi; Ken Lee

    1999-01-01

    To investigate mechanisms involved in hepatoportal Na+ sensing, responses of hepatic afferent nerve activity (HANA) to intraportal hypertonic NaCl injection were measured before, and after, intraportal infusion of inhibitors of Na+ transport systems. HANA increased in response to the intraportal injection of 0.75 M NaCl in a dose-dependent manner. The HANA response was not affected by amiloride or 4-acetamido-4?-isothiocyanato-stilbene-2,2?-disulfonic acid

  2. Energy metabolism, intracellular Na + and contractile function in isolated pig and rat hearts during cardioplegic ischemia and reperfusion: 23 Na and 31 P-NMR studies

    Microsoft Academic Search

    V. V. Kupriyanov; B. Xiang; K. W. Butler; M. St-Jean; R. Deslauriers

    1995-01-01

    The purpose of the study was to compare the role of Na ions in the damage caused by cardioplegic ischemia in fast (rat) and slow (pig) hearts. Changes in intracellular Na+ (Na+i), high energy phosphates, and contractile function were assessed during ischemia (36°C) and reperfusion in KCl-arrested perfused hearts using31P-NMR and shift reagent (DyTTHA3-)-aided23Na-NMR spectroscopy. In the pig hearts the

  3. Calculations of nonlinear optical responses of isomorphous crystals NaClO 3 and NaBrO 3 with natural optical activity

    Microsoft Academic Search

    Dongfeng Xue; Siyuan Zhang

    1998-01-01

    This work considers the isomorphous optically active crystals NaClO3 and NaBrO3. The connection between their second-order nonlinear optical (NLO) responses and chemical bond structures is established, starting from the experimental optical activities. The calculation reproduces the well-known experimental fact that crystals of NaClO3 and NaBrO3 with similar structures have different signs of optical rotation and of second harmonic generation (SHG).

  4. Expression cloning and cDNA sequencing of the Na+\\/glucose co-transporter

    Microsoft Academic Search

    Matthias A. Hediger; Michael J. Coady; Tyson S. Ikeda; Ernest M. Wright

    1987-01-01

    Organic substrates (sugars, amino acids, carboxylic acids and neutrotransmitters) are actively transported into eukaryotic cells by Na+ co-transport. Some of the transport proteins have been identified-for example, intestinal brush border Na+\\/glucose and Na+\\/proline transporters1,2 and the brain Na+\\/Cl-\\/GABA transporter3-and progress has been made in locating their active sites and probing their conformational states1,2,4-7. The archetypical Na+-driven transporter is the intestinal

  5. Binding energy and structure of e{sup +}Na

    SciTech Connect

    Shertzer, J. [Department of Physics, College of the Holy Cross, Worcester, Massachusetts 01610 (United States); Ward, S. J. [Department of Physics, University of North Texas, Denton, Texas 76203 (United States)

    2010-06-15

    We calculate the nonadiabatic binding energy and geometry of the weakly bound state of e{sup +}Na. We use the Peach model potential, which includes both the dipole and an effective quadrupole term in the polarization, to describe the interaction of the electron and positron with the ion core. The effective three-body Schroedinger equation is solved with the finite element method. Because the model potential gives rise to three spurious states, the true ground state of e{sup +}Na is embedded in a dense spectrum of spurious states. We develop a method for extracting the correct ground state for e{sup +}Na, even when the energy is nearly degenerate with a spurious level. The calculated value for the binding energy is consistent with other calculations.

  6. Binding energy and structure of e+Na

    NASA Astrophysics Data System (ADS)

    Shertzer, J.; Ward, S. J.

    2010-06-01

    We calculate the nonadiabatic binding energy and geometry of the weakly bound state of e+Na. We use the Peach model potential, which includes both the dipole and an effective quadrupole term in the polarization, to describe the interaction of the electron and positron with the ion core. The effective three-body Schrödinger equation is solved with the finite element method. Because the model potential gives rise to three spurious states, the true ground state of e+Na is embedded in a dense spectrum of spurious states. We develop a method for extracting the correct ground state for e+Na, even when the energy is nearly degenerate with a spurious level. The calculated value for the binding energy is consistent with other calculations.

  7. NaCl as a retrospective and accident dosemeter.

    PubMed

    Ekendahl, Daniela; Judas, Libor

    2011-04-01

    NaCl is a cheap and widely available material. This study investigated the potential of NaCl in the form of a household salt as a retrospective and accident dosemeter using optically stimulated luminescence (OSL). Samples of the investigated household salt were stimulated using blue light of linearly modulated power. Attention was concentrated on sensitivity, dose dependence of the OSL signal, fading, optimisation of the read-out procedure and application of analytical protocols that do not require a specific calibration. A potential of NaCl as a complementary dosemeter within emergency preparedness was considered. The behaviour of the OSL signal observed was found to be favourable for dosimetry. PMID:21068016

  8. Theoretical simulation of the photoassociation process for NaCs

    NASA Astrophysics Data System (ADS)

    Zhang, Chang-Zhe; Zheng, Bin; Wang, Jun; Meng, Qing-Tian

    2013-02-01

    We investigate the two-step association process of NaCs using the time-dependent wave packet method. Ground state atoms can be photoassociated to the low vibrational levels of the ground state for an NaCs molecule by the two-step association. The time-dependent Schrödinger equation of the association process is solved within a three-state model and the wave packet is propagated with the “split operator-Fourier transform" scheme and the rotating-wave approximation (RWA). The vibrational population distribution of the ground state can be obtained by projecting the wave packet to every vibrational level of the ground state. The results not only show that for NaCs achievement of photoassociation production is accompanied by the photodissociation of the higher vibrational molecules, but also show that the vibrational distribution in lower vibrational levels of the ground state changes with the laser parameters.

  9. HARP and NA61 (SHINE) hadron production experiments

    SciTech Connect

    Popov, Boris A. [LPNHE, 4 place Jussieu, 75005, Paris and DLNP, JINR, Joliot-Curie 6, 141980, Dubna (Russian Federation)

    2009-11-25

    The hadroproduction experiments HARP and NA61 (SHINE) as well as their implications for neutrino physics are discussed. Recent HARP measurements have already been used for precise predictions of neutrino beams in K2K and MiniBooNE/SciBooNE experiments and are also being used to improve the atmospheric neutrino flux predictions and to help in the optimization of neutrino factory and super-beam designs. First preliminary data from NA61 are of significant importance for a precise prediction of a new neutrino beam at J-PARC to be used for the first stage of the T2K experiment. Both HARP and NA61 provide a large amount of input for validation and tuning of hadroproduction models in Monte-Carlo generators.

  10. Solvation of Na+, K+, and Their Dimers in Helium

    PubMed Central

    An der Lan, Lukas; Bartl, Peter; Leidlmair, Christian; Jochum, Roland; Denifl, Stephan; Echt, Olof; Scheier, Paul

    2012-01-01

    Helium atoms bind strongly to alkali cations which, when embedded in liquid helium, form so-called snowballs. Calculations suggest that helium atoms in the first solvation layer of these snowballs form rigid structures and that their number (n) is well defined, especially for the lighter alkalis. However, experiments have so far failed to accurately determine values of n. We present high-resolution mass spectra of Na+Hen, K+Hen, Na2+Hen and K2+Hen, formed by electron ionization of doped helium droplets; the data allow for a critical comparison with several theoretical studies. For sodium and potassium monomers the spectra indicate that the value of n is slightly smaller than calculated. Na2+Hen displays two distinct anomalies at n=2 and n=6, in agreement with theory; dissociation energies derived from experiment closely track theoretical values. K2+Hen distributions are fairly featureless, which also agrees with predictions. PMID:22374575

  11. The stability of sodalite in the system NaAlSiO sub 4 -NaCl

    SciTech Connect

    Sharp, Z.D. (Carnegie Institution of Washington, DC (USA)); Helffrich, G.R. (Northwestern Univ., Evanston, IL (USA)); Bohlen, S.R. (S.U.N.Y., Stony Brook, NY (USA)); Essene, E.J. (Univ. of Michigan, Ann Arbor (USA))

    1989-08-01

    The reaction sodalite = {beta}-nepheline + NaCl (s) was reversed in solid-medium apparatus and the reaction sodalite = carnegieite + NaCl (l) was reversed at 1 bar (1,649-1,652 K). The experimental reversals between 923 K and 973 K can be fit with a dP/dT of {minus}11 bar/K, suggesting that the excess entropy for sodalite is present only above 923 K. A phase diagram for the NaAlSiO{sub 4}-NaCl system that is consistent with the measured thermochemical data and the experiments between 973 and 1,650 K can be generated if the 61.7 J/mol{center dot}K entropy contribution is included in the S{sup 0}{sub 298} of sodalite. This entropy contribution must be removed below 973 K for the experiments to fit with calculations. Previously unreported thermodynamic data estimated in this study are {Delta}G{sup 0}{sub 298} for sodalite ({minus}12,697 kJ/mol) and carnegieite (NaAlSiO{sub 4}) ({minus}1,958 kJ/mol), S{sup 0}{sub 298} of carnegieite (129.6 J/mol{center dot}K) and compressibility of NaCl{sub liquid} (V{sup P}{sub 298} (cm{sup 3}) = 31.6{center dot}(1 - 24.7{center dot}10{sup {minus}3}{center dot}P + 800{center dot}10{sup {minus}6}{center dot}P{sup 2}))(T in K; P in kbar). Sodalite is a high-temperature, low-pressure phase, stable well above the solidus in sodic silica-undersaturated magmas enriched in NaCl, and its presence constrains NaCl activities in magmas. Estimates of minimum NaCl (l) activities in the Mont St-Hilaire sodalite syenites are 0.05 at 1,073 K and 0.13 at 1,273 K. Density calculations are consistent with the field observations that sodalite phenocrysts will float in a nepheline syenite liquid. This explains the enrichment of sodalite in the upper levels of the sodalite syenites at Mont St.Hilaire and elsewhere.

  12. The voltage-gated Na+ channel NaVBP has a role in motility, chemotaxis, and pH homeostasis of an alkaliphilic Bacillus

    PubMed Central

    Ito, Masahiro; Xu, Haoxing; Guffanti, Arthur A.; Wei, Yi; Zvi, Lior; Clapham, David E.; Krulwich, Terry A.

    2004-01-01

    The prokaryotic voltage-gated Na+ channel, NaChBac, is one of a growing channel superfamily of unknown function. Here we show that NaVBP, the NaChBac homologue encoded by ncbA in alkaliphilic Bacillus pseudofirmus OF4, is a voltage-gated Na+ channel potentiated by alkaline pH. NaVBP has roles in motility, chemotaxis, and pH homeostasis at high pH. Reduced motility of bacteria lacking functional NaVBP was reversed by restoration of the native channel but not by a mutant NaVBP engineered to be Ca2+-selective. Motile ncbA mutant cells and wild-type cells treated with a channel inhibitor exhibited behavior opposite to the wild type in response to chemoeffectors. Mutants lacking functional NaVBP were also defective in pH homeostasis in response to a sudden alkaline shift in external pH under conditions in which cytoplasmic [Na+] is limiting for this crucial process. The defect was exacerbated by mutation of motPS, the motility channel genes. We hypothesize that activation of NaVBP at high pH supports diverse physiological processes by a combination of direct and indirect effects on the Na+ cycle and the chemotaxis system. PMID:15243157

  13. Shoot Na+ Exclusion and Increased Salinity Tolerance Engineered by Cell Type–Specific Alteration of Na+ Transport in Arabidopsis[W][OA

    PubMed Central

    Møller, Inge S.; Gilliham, Matthew; Jha, Deepa; Mayo, Gwenda M.; Roy, Stuart J.; Coates, Juliet C.; Haseloff, Jim; Tester, Mark

    2009-01-01

    Soil salinity affects large areas of cultivated land, causing significant reductions in crop yield globally. The Na+ toxicity of many crop plants is correlated with overaccumulation of Na+ in the shoot. We have previously suggested that the engineering of Na+ exclusion from the shoot could be achieved through an alteration of plasma membrane Na+ transport processes in the root, if these alterations were cell type specific. Here, it is shown that expression of the Na+ transporter HKT1;1 in the mature root stele of Arabidopsis thaliana decreases Na+ accumulation in the shoot by 37 to 64%. The expression of HKT1;1 specifically in the mature root stele is achieved using an enhancer trap expression system for specific and strong overexpression. The effect in the shoot is caused by the increased influx, mediated by HKT1;1, of Na+ into stelar root cells, which is demonstrated in planta and leads to a reduction of root-to-shoot transfer of Na+. Plants with reduced shoot Na+ also have increased salinity tolerance. By contrast, plants constitutively expressing HKT1;1 driven by the cauliflower mosaic virus 35S promoter accumulated high shoot Na+ and grew poorly. Our results demonstrate that the modification of a specific Na+ transport process in specific cell types can reduce shoot Na+ accumulation, an important component of salinity tolerance of many higher plants. PMID:19584143

  14. Quaternary Organic Amines Inhibit Na,K Pump Current in a Voltage-dependent Manner: Direct Evidence of an Extracellular Access Channel in the Na,K-ATPase

    Microsoft Academic Search

    R. Daniel Peluffo; Yukio Hara; Joshua R. Berlin

    2004-01-01

    The effects of organic quaternary amines, tetraethylammonium (TEA) chloride and benzyltrieth- ylammonium (BTEA) chloride, on Na,K pump current were examined in rat cardiac myocytes superfused in ex- tracellular Na ? -free solutions and whole-cell voltage-clamped with patch electrodes containing a high Na ? -salt so- lution. Extracellular application of these quaternary amines competitively inhibited extracellular K ? (Ko ) activa-

  15. O IMPACTO DA ARMAZENAGEM DA SOJA NA PROPRIEDADE RURAL SOBRE OS PREÇOS DE MERCADO DA COMMODITY E NA AMPLIAÇÃO DA CAPACIDADE DE ARMAZENAMENTO

    Microsoft Academic Search

    Lenio Tramontina; Edson Talamini; Gabriel Murad Velloso Ferreira

    2008-01-01

    O presente trabalho consiste em um estudo realizado com objetivo principal de avaliar o impacto do aumento na capacidade de armazenagem de soja na propriedade rural, sobre o nível de preços da commodity e deste sobre a viabilidade de novos incrementos na capacidade de armazenagem. Para o seu desenvolvimento aplicou-se um estudo exploratório, baseado no levantamento e análise de dados

  16. Rechargeable sodium batteries; NaFeO sub 2 and FeOCl as positive electrodes in molten NaAlCl sub 4

    SciTech Connect

    Abraham, K.M.; Pasquariello, D.M. (EIC Labs., Inc., Norwood, MA (USA))

    1990-04-01

    The authors have conducted studies in which they found that NaFeO{sub 2} and FeOCl behave as highly reversible positive electrodes in conjunction with molten NaAlCl{sub 4} in Na cells operating at {approximately} 180{degrees}C. Results of the studies are discussed.

  17. Measurement of low-energy Na^+ -- Na total collision rate in an ion--neutral hybrid trap

    E-print Network

    Goodman, D S; Kwolek, J M; Blümel, R; Narducci, F A; Smith, W W

    2014-01-01

    We present measurements of the total elastic and resonant charge-exchange ion-atom collision rate coefficient $k_\\mathrm{ia}$ of cold sodium (\\ce{Na}) with optically-dark low energy \\ce{Na+} ions in a hybrid ion-neutral trap. To determine $k_\\mathrm{ia}$, we measured the trap loading and loss from both a \\ce{Na} magneto-optical trap (MOT) and a linear radio frequency quadrupole Paul trap. We found the total rate coefficient to be $7.4 \\pm 1.9 \\times 10^{-8}$ cm$^3$/s for the type I \\ce{Na} MOT immersed within an $\\approx 140$ K ion cloud and $1.10 \\pm 0.25 \\times 10^{-7}$ cm$^3$/s for the type II \\ce{Na} MOT within an $\\approx 1070$ K ion cloud. Our measurements show excellent agreement with previously reported theoretical fully quantal \\textit{ab initio} calculations. In the process of determining the total rate coefficient, we demonstrate that a MOT can be used to probe an optically dark ion cloud's spatial distribution within a hybrid trap.

  18. Brain Na+, K+-ATPase Activity In Aging and Disease

    PubMed Central

    de Lores Arnaiz, Georgina Rodríguez; Ordieres, María Graciela López

    2014-01-01

    Na+/K+ pump or sodium- and potassium-activated adenosine 5’-triphosphatase (Na+, K+-ATPase), its enzymatic version, is a crucial protein responsible for the electrochemical gradient across the cell membranes. It is an ion transporter, which in addition to exchange cations, is the ligand for cardenolides. This enzyme regulates the entry of K+ with the exit of Na+ from cells, being the responsible for Na+/K+ equilibrium maintenance through neuronal membranes. This transport system couples the hydrolysis of one molecule of ATP to exchange three sodium ions for two potassium ions, thus maintaining the normal gradient of these cations in animal cells. Oxidative metabolism is very active in brain, where large amounts of chemical energy as ATP molecules are consumed, mostly required for the maintenance of the ionic gradients that underlie resting and action potentials which are involved in nerve impulse propagation, neurotransmitter release and cation homeostasis. Protein phosphorylation is a key process in biological regulation. At nervous system level, protein phosphorylation is the major molecular mechanism through which the function of neural proteins is modulted in response to extracellular signals, including the response to neurotransmitter stimuli. It is the major mechanism of neural plasticity, including memory processing. The phosphorylation of Na+, K+-ATPase catalytic subunit inhibits enzyme activity whereas the inhibition of protein kinase C restores the enzyme activity. The dephosphorylation of neuronal Na+, K+-ATPase is mediated by calcineurin, a serine / threonine phosphatase. The latter enzyme is involved in a wide range of cellular responses to Ca2+ mobilizing signals, in the regulation of neuronal excitability by controlling the activity of ion channels, in the release of neurotransmitters and hormones, as well as in synaptic plasticity and gene transcription. In the present article evidence showing Na+, K+-ATPase involvement in signaling pathways, enzyme changes in diverse neurological diseases as well as during aging, have been summarized. Issues refer mainly to Na+, K+-ATPase studies in ischemia, brain injury, depression and mood disorders, mania, stress, Alzheimer´s disease, learning and memory, and neuronal hyperexcitability and epilepsy. PMID:25018677

  19. Possible selective adsorption of enantiomers by Na-montmorillonite

    NASA Technical Reports Server (NTRS)

    Friebele, E.; Shimoyama, A.; Ponnamperuma, C.

    1981-01-01

    Racemic amino acids including (D,L) alpha-alamine, (D,L) alpha-aminobutyric acid, (D,L) valine, and (D,L) norvaline were incubated with Na-montmorillonite at 100% CEC at three hydrogen ion concentrations, and amino acid adsorption was determined by ion exchange chromatography. Enantiomers were analyzed by gas chromatography. Differences in the quantities of D and L enantiomers in any of the fractions was no larger than a few percent. Although a large difference in the adsorption of the amino acid enantiomers was not observed, the analysis may indicate a small preferential adsorption (0.5-2%) of L-amino acids by Na-montmorillonite.

  20. Olivine-type NaCd(AsO4)

    PubMed Central

    Weil, Matthias

    2013-01-01

    The title compound, sodium cadmium orthoarsenate, adopts the olivine [Mg2(SiO4)] structure type in space group Pnma, with Na (site symmetry -1) and Cd (.m.) replacing the two Mg positions, and the AsO4 tetra­hedron (.m.) the SiO4 tetra­hedron. The crystal structure is made up of a nearly hexa­gonal closed-packed arrangement of O atoms stacked along [001]. The Na and Cd atoms occupy one half of the octa­hedral voids in alternate layers stacked along [100], and one eighth of the tetra­hedral voids are occupied by As atoms. PMID:24454011

  1. Študent naj bo na ameriškem kolidžu

    E-print Network

    Pirnat-Greenberg, Marta

    2007-01-01

    , že po obi?aju zelo naporen del leta, jaz pa sem letos s težavo prisopihala komaj do konca zime. Teh po?itnic sem se veselila, da se malo naspim in postorim vsaj nekaj stvari, s katerimi sem v zaostanku. Zelo se mi prileže, da imam na voljo ve? ?asa.... Ni? ne pomaga dokazovanje, da je poletna šola slovenskega jezika v Ljubljani zelo intenZivna, da vsebuje ve? kot zahtevano števi10 ur v štiritedenskem programu, da šesttedenski program v Sloveniji ne obstaja in da se na izpopolnjevalni stopnji...

  2. El Valor de los Estuarios Saludables

    NSDL National Science Digital Library

    Robert Christian (Thomas Harriot College of Arts and Sciences; )

    2009-09-05

    Healthy estuaries are critical to humans and wildlife. They provide food, supporting both commercial and recreational fisheries; treat waste and runoff, maintaining water quality; protect coastal areas from natural hazards; connect bodies of water for transportation and marine operations; and nurture a balance of the food web upon which all life depends.

  3. In Situ SAXS/WAXS of Zeolite Microwave Synthesis: NaY, NaA, and Beta Zeolites

    SciTech Connect

    Panzarella,B.; Tompsett, G.; Conner, W.; Jones, K.

    2007-01-01

    A custom waveguide apparatus is constructed to study the microwave synthesis of zeolites by in situ small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). The WR-284 waveguide is used to heat precursor solutions using microwaves at a frequency of 2.45 GHz. The reaction vessels are designed to include sections of thin-walled glass, which permit X-rays to pass through the precursor solutions with minimal attenuation. Slots were machined into the waveguide to provide windows for X-ray energy to enter and scatter from solutions during microwave heating. The synthesis of zeolites with conventional heating is also studied using X-ray scattering in the same reactor. SAXS studies show that the crystallization of beta zeolite and NaY zeolite is preceded by a reorganization of nanosized particles in their precursor solutions or gels. The evolution of these particles during the nucleation and crystallization stages of zeolite formation depends on the properties of the precursor solution. The synthesis of NaA and NaX zeolites and sodalite from a single zeolite precursor is studied by microwave and conventional heating. Microwave heating shifts the selectivity of this synthesis in favor of NaA and NaX over sodalite; conventional heating leads to the formation of sodalite for synthesis from the same precursor. The use of microwave heating also led to a more rapid onset of NaA zeolite product crystallization compared to conventional heating. Pulsed and continuous microwave heating are compared for zeolite synthesis. The resulting rates of formation of the zeolite products, and the relative amounts of the products determined from the WAXS spectra, are similar when either pulsed or continuous microwave heating is applied in the reactor while maintaining the same synthesis temperature. The consequences of these results in terms of zeolite synthesis are discussed.

  4. Development of illumination optics and projection optics for high-NA EUV exposure tool (HiNA)

    NASA Astrophysics Data System (ADS)

    Oshino, Tetsuya; Shiraishi, Masayuki; Kandaka, Noriaki; Sugisaki, Katsumi; Kondo, Hiroyuki; Ota, Kazuya; Mashima, K.; Murakami, Katsuhiko; Oizumi, Hiroaki; Nishiyama, Iwao; Okazaki, Shinji

    2003-06-01

    We have developed a high numerical aperture (NA) small-field exposure system (HiNA) for EUV exposure process development. NA of projection optics of EUV exposure tools for 45-nm node lithography is expected to be around 0.25, which is higher than that previously expected (0.1). HiNA has compatible illumination system, which can be switched to partial coherent illumination and coherent illumination by changing some optical elements. Coherent illumination system was prepared for a high contrast imaging but the uniformity of intensity is less than that of partial coherent illumination. A reflected-type fly*fs-eye element was adopted for partial coherent illumination, which can provide uniformity of both coherency and intensity simultaneously. The coherency of the partial coherent illumination is 0.8. HiNA projection optics consists of two aspheric mirrors, with the NA and the imaging field of 0.3 and 0.3×0.5mm2, respectively. We fabricated two sets of projection-optics. Although the wavefront error of set-1 optics was 7nmRMS, that of set-2 optics was improved to 1.9nmRMS, which was measured with a point diffraction interferometer (PDI) using He-Ne laser. The wavefront error of the set-2 optics was improved by using a new mirror mount mechanism. The mount system consists of several board springs made of super invar in order to minimize the deformation of mirrors by mounting stress. The projection optics of the set-2 has a remote controlled mirror adjustment mechanism which has five degrees of freedom (X,Y,Z,X-Tilt and Y-Tilt). The position of the concave secondary mirror was adjusted precisely with measuring the wavefront error using PDI.

  5. Laser vaporized Li2, Na2, K2, and LiNa molecules observed by cavity ring-down spectroscopy

    NASA Astrophysics Data System (ADS)

    Labazan, I.; Miloševi?, S.

    2003-09-01

    Laser ablation of solid lithium, sodium, potassium, and lithium-sodium alloy was performed using a 308-nm excimer laser at fluences close to 1 J cm-2. Frequency and time resolved A-X and B-X electronic transitions of 6,7Li2, Na2, LiNa and K2 respectively, were observed. Lithium atom, dimer velocities, and influence of the background gas on dimer content of the plume have been measured. The origin of dimers at high densities, with subthermal internal energy, is discussed.

  6. Spin assignments to excited states in 22Na through a 24Mg(p,3He)22Na reaction measurement

    SciTech Connect

    Chae, K. Y. [University of Tennessee; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chipps, K. [Colorado School of Mines, Golden; Hatarik, Robert [Rutgers University; Jones, K. L. [University of Tennessee; Kozub, R. L. [Tennessee Technological University; Liang, J Felix [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee; Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Pain, S. D. [Rutgers University; Pittman, S. T. [University of Tennessee, Knoxville (UTK); Smith, Michael Scott [ORNL

    2010-10-01

    The level structure of 22Na has been studied at the Holifield Radioactive Ion Beam Facility in Oak Ridge National Laboratory using the 24Mg(p,3He)22Na reaction. 41 and 41.5 MeV proton beams were generated by 25 MV tandem accelerator and bombarded isotopically enriched 24Mg targets. Angular distributions of recoiling 3He particles were extracted by using a segmented annular silicon strip detector array. Spins and parities for ten levels were constrained through a distorted wave Born approximation analysis of angular distributions including three above the proton threshold at 6.739 MeV.

  7. O, Na, Ba and Eu abundance patterns in open clusters

    NASA Astrophysics Data System (ADS)

    MacLean, B. T.; De Silva, G. M.; Lattanzio, J.

    2015-02-01

    Open clusters are historically regarded as single-aged stellar populations representative of star formation within the Galactic disc. Recent literature has questioned this view, based on discrepant Na abundances relative to the field, and concerns about the longevity of bound clusters contributing to a selection bias: perhaps long-lived open clusters are chemically different to the star formation events that contributed to the Galactic disc. We explore a large sample of high-resolution Na, O, Ba and Eu abundances from the literature, homogenized as much as reasonable including accounting for non-local thermodynamic equilibrium (NLTE) effects, variations in analysis and choice of spectral lines. Compared to a template globular cluster and representative field stars, we find no significant abundance trends, confirming that the process producing the Na-O anticorrelation in globular clusters is not present in open clusters. Furthermore, previously reported Na enhancement of open clusters is found to be an artefact of NLTE effects, with the open clusters matching a subset of chemically tagged field stars.

  8. Stainless Steel NaK Circuit Integration and Fill Submission

    NASA Technical Reports Server (NTRS)

    Garber, Anne E.

    2006-01-01

    The Early Flight Fission Test Facilities (EFF-TF) team has been tasked by the Marshall Space Flight Center Nuclear Systems Office to design, fabricate, and test an actively pumped alkali metal flow circuit. The system, which was originally designed to hold a eutectic mixture of sodium potassium (NaK), was redesigned to hold lithium; but due to a shift in focus, it is once again being prepared for use with NaK. Changes made to the actively pumped, high temperature loop include the replacement of the expansion reservoir, addition of remotely operated valves, and modification of the support table. Basic circuit components include: reactor segment, NaK to gas heat exchanger, electromagnetic (EM) liquid metal pump, load/drain reservoir, expansion reservoir, instrumentation, and a spill reservoir. A 37-pin partial-array core (pin and flow path dimensions are the same as those in a full design) was selected for fabrication and test. This document summarizes the integration and fill of the pumped liquid metal NaK flow circuit.

  9. POLMEROS EM SUPERFCIES Polmeros adsorvidos na superfcies de partculas

    E-print Network

    Loh, Watson

    POLÍMEROS EM SUPERFÍCIES Polímeros adsorvidos na superfícies de partículas coloidais Polímeros em interfaces líquidas Polímeros em interfaces sólidas #12;Polímeros em solução - Teoria de Flory-Hugghins #12;Polímeros em solução - Teoria de Flory-Hugghins Gm = kT(1ln1 + 2/N ln2 + 12) 1 = solvente 2 = polímero (Gm

  10. Characteristics optimization of mask materials for hyper-NA lithography

    Microsoft Academic Search

    Yasutaka Morikawa; Takanori Suto; Takaharu Nagai; Yuichi Inazuki; Takashi Adachi; Yasuhisa Kitahata; Toshifumi Yokoyama; Nobuhito Toyama; Hiroshi Mohri; Naoya Hayashi

    2007-01-01

    Hyper-NA lithography with polarized light illumination is introduced as the solution of 45nm or 32nm node technology. In that case, consideration of new characteristics of masks and substrates has been required. Mainly, following three materials, quartz substrates, absorber or phase shifter materials and pellicle films, have been discussed for that issue. Item to be discussed on quartz substrates is birefringence.

  11. Catadioptric projection lens for 1.3 NA scanner

    NASA Astrophysics Data System (ADS)

    Matsuyama, Tomoyuki; Ohmura, Yasuhiro; Fujishima, Yohei; Koyama, Takashi

    2007-03-01

    In the history of DUV (Deep Ultra Violet) microlithographic lens design, three kinds of leaps have occurred to maintain the progress of technology in the semiconductor industry. The first step is the application of aspherical elements. This allowed us to increase NA up to around 0.9. The second innovation is water immersion. Thanks to the 1.44 refractive index of water, and because the numerical aperture (NA) is defined as the product of the sine of the maximum ray angle on the image plane and the refractive index in the image space, even with a lower maximum ray angle on the imaging plane than dry with a lens, we can achieve NA of 1.07. The latest technological jump is the development of catadioptric lens systems, which are roughly defined as the combined usage of refractive element(s) and reflective element(s). The catadioptric system allows us to achieve a full field 1.3NA projection lens that is used in our scanner NSR-S610C. In this paper we discuss optical design concepts and some challenges for catadioptric lenses. In addition, current lens performance including wavefront, lens flare, and image vibration are shown.

  12. NaK release model for MASTER-2009

    NASA Astrophysics Data System (ADS)

    Wiedemann, Carsten; Flegel, Sven; Gelhaus, Johannes; Krag, Holger; Klinkrad, Heiner; Vörsmann, Peter

    2011-04-01

    Sodium-potassium droplets from the primary coolant loop of Russian orbital reactors have been released into space. These droplets are called NaK droplets. Sixteen nuclear powered satellites of the type RORSAT launched between 1980 and 1988 activated a reactor core ejection system, mostly between 900 and 950 km altitude. The core ejection causes an opening of the primary coolant loop. The liquid coolant consists of eutectic sodium-potassium alloy and has been released into space during these core ejections. The NaK coolant has been forming droplets up to a diameter of 5.5 cm. NaK droplets have been modeled before in ESA's MASTER Debris and Meteoroid Environment Model. The approach is currently revised for the MASTER-2009 upgrade. A mathematical improvement is introduced by substituting the current size distribution function by the modified Rosin-Rammler equation. A bimodal size distribution is derived which is based on the modified mass based Rosin-Rammler equation. The equation is modified by truncating the size range and normalizing over the finite range between the size limits of the smallest and the biggest droplet. The parameters of the model are introduced and discussed. For the validation of the NaK release model, sixteen release events are simulated. The resulting size distribution is compared with radar measurement data. The size distribution model fits well with revised published measurement data of radar observations. Results of orbit propagation simulation runs are presented in terms of spatial density.

  13. Grant Title: STARR FOUNDATION Funding Opportunity Number: N/A

    E-print Network

    Farritor, Shane

    Grant Title: STARR FOUNDATION Funding Opportunity Number: N/A Agency/Department: Starr Foundation Grants Program. Area of Research: The foundation makes grants in the following areas: education, medicine and post-secondary schools. Grants for medicine and health care include capital grants to hospitals

  14. Grant Title: CORNING FOUNDATION Funding Opportunity Number: N/A

    E-print Network

    Farritor, Shane

    Grant Title: CORNING FOUNDATION Funding Opportunity Number: N/A Agency/Department: Corning: The Corning Incorporated Foundation develops and administers projects in support of educational, cultural which improve the quality of life in and near communities where Corning Incorporated is an active

  15. Results from NA60 experiment at the CERN SPS

    SciTech Connect

    Usai, G.; Cicalo, C.; De Falco, A.; Floris, M.; Masoni, A.; Puddu, G.; Serci, S. [Univ. di Cagliari, Cagliari (Italy); INFN, Cagliari (Italy); Arnaldi, R.; Colla, A.; Cortese, P.; Ferretti, A.; Oppedisano, C. [Univ. di Torino (Italy) and INFN (Italy); Averbeck, R.; Drees, A. [SUNY Stony Brook, New York (United States); Banicz, K. [CERN, Geneva (Switzerland); Univ. Heidelberg, Heidelberg (Germany); Castor, J.; Devaux, A.; Force, P.; Manso, F. [LPC, Univ. Blaise Pascal, Clermont-Ferrand (France); CNRS-IN2P3, Clermont-Ferrand (France); Chaurand, B. [LLR, Ecole Polytechnique, Palaiseau (France); CNRS-IN2P3, Palaiseau (France)] (and others)

    2006-07-11

    The NA60 experiment studies open charm and prompt dimuon production in proton-nucleus and nucleus-nucleus collisions at the CERN SPS. During 2003 the experiment collected data in Indium-Indium collisions at 158 GeV per nucleon. In this paper the first results on low mass dimuons, intermediate mass dimuons and J/{psi} suppression are presented.

  16. Electronic structure and molecular dynamics of Na2Li

    Microsoft Academic Search

    Nathaniel O. J. Malcolm; Joseph J. W. McDouall

    1997-01-01

    Following the first report (Mile, B., Sillman, P. D., Yacob, A. R. and Howard, J. A., 1996, J. chem. Soc. Dalton Trans , 653) of the EPR spectrum of the mixed alkali-metal trimer Na2Li a detailed study has been made of the electronic structure and structural dynamics of this species. Two isomeric forms have been found: one of the type,

  17. Formation of oriented membrane multilayers of Na/K-ATPase

    SciTech Connect

    Pachence, J.M.; Knott, R.; Edelman, I.S.; Schoenborn, B.P.; Wallace, B.A.

    1982-01-01

    The isolated membrane-bound enzyme retains its ouabain-sensitive ATP hydrolysis activity, and produces ATP-dependent Na/sup +/ and K/sup +/ fluxes when incorporated into phospholipid vesicles. The ultimate goal of this work is to determine its low resolution structure using both X-ray and neutron diffraction. A number of methods were used to impart lamellar stacking order to highly purified pig Na/K-ATPase membranes. Upon partial dehydration, x-ray diffraction from Na/K-ATPase membrane multilayers at 98% relative humidity yielded discrete reflections of 118 A periodicity, diffracting to 1/14.8 A/sup -1/, additionally, continuous diffraction to 1/10 A/sup -1/ was obtained. Subjecting the membrane multilayers to high magnetic fields improved the quality of the lamellar diffraction dramatically. Neutron diffraction studies of the partially dehydrated Na/K-ATPase membrane multilayers detected a mosaic spread of 2/sup 0/ when the samples were subjected to a magnetic field of 5 Tesla perpendicular to the membrane surface; the reflections were narrower than the camera line width; hence, the lattice disorder has also decreased significantly, although only four orders were measured.

  18. Exploring Neutron-Rich Oxygen Isotopes with MoNA

    E-print Network

    N. Frank; T. Baumann; D. Bazin; J. Brown; P. A. DeYoung; J. E. Finck; A. Gade; J. Hinnefeld; R. Howes; J. -L. Lecouey; B. Luther; W. A. Peters; H. Scheit; A. Schiller; M. Thoennessen

    2007-08-20

    The Modular Neutron Array (MoNA) was used in conjunction with a large-gap dipole magnet (Sweeper) to measure neutron-unbound states in oxygen isotopes close to the neutron dripline. While no excited states were observed in 24O, a resonance at 45(2) keV above the neutron separation energy was observed in 23O.

  19. Mechanism of two types of Na emission observed in sonoluminescence

    NASA Astrophysics Data System (ADS)

    Nakajima, Ryota; Hayashi, Yuichi; Choi, Pak-Kon

    2015-07-01

    The sonoluminescence (SL) spectrum of Na atoms revealed that the Na line consists of two components, one of which is a broadened component (broad component) which is shifted from the original D lines, and the other is an unshifted narrow component (narrow component). We spatially separated the continuum, broad, and narrow components by capturing SL images using different optical filters. We also temporally separated these components by measuring SL pulses using respective band-pass filters. The SL image distribution and the timing of the SL pulses were different between the broad and narrow components. The results suggested that the broad and narrow components of Na emission are generated from different bubble populations. The dependences of SL spectra on ultrasonic frequency and dissolved rare gas (He, Ne, Ar, Kr, and Xe) were also investigated. It is concluded that the broad component and a blue satellite peak at 558 nm originate from van der Waals molecules composed of Na and rare-gas atoms. The narrow component was predicted to occur under temperature conditions at bubble collapse higher than that for the broad component.

  20. Results from CERN experiment NA36 on strangeness production

    SciTech Connect

    Not Available

    1991-12-01

    Measurements of the production of strange particles in the reactions S + Pb and S + S at beam momentum 200GeV/c per nucleon are presented. A short description of CERN experiment NA36 and the methods of raw data analysis, is followed by physics results concentrating on the dependence of strange particle production on multiplicity. Transverse momentum distributions are also presented.

  1. Study of a Large NaI(T1)Crystal

    SciTech Connect

    Kettell, S.; Littenberg, L.

    2010-03-12

    Using a narrow band positron beam, the response of a large high-resolution NaI(Ti) crystal to an incident positron beam was measured. It was found that nuclear interactions cause the appearance of additional peaks in the low energy tail of the deposited energy spectrum.

  2. Free Energy for the Permeation of Na+ Ions and Their

    E-print Network

    Lu, Benzhuo

    such hydrophilic ions as Na+ and Cl- does not assist their permeation. However, based on a simple thermodynamic difficult. On the other hand more convoluted, macroscopic properties such as ion permeation or leakage rate permeate lipid bilayers differently from halide ions, with the overall permeation rate for the Cl- being

  3. Altered erythrocyte Na-K pump in anorectic patients

    SciTech Connect

    Pasquali, R.; Strocchi, E.; Malini, P.; Casimirri, F.; Ambrosioni, E.; Melchionda, N.; Labo, G.

    1985-07-01

    The status of the erythrocyte sodium pump was evaluated in a group of patients suffering from anorexia nervosa and a group of healthy female control subjects. Anorectic patients showed significantly higher mean values of digoxin-binding sites/cell (ie, the number of Na-K-ATPase units) with respect to control subjects while no differences were found in the specific /sup 86/Rb uptake (which reflects the Na-K-ATPase activity) between the two groups. A significant correlation was found between relative weight and the number of Na-K-ATPase pump units (r = -0.66; P less than 0.0001). Anorectic patients showed lower serum T3 concentrations (71.3 +/- 53 ng/dL) with respect to control subjects (100.8 +/- 4.7 ng/dL; P less than 0.0005) and a significant negative correlation between T3 levels and the number of pump units (r = -0.52; P less than 0.003) was found. This study therefore shows that the erythrocyte Na-K pump may be altered in several anorectic patients. The authors suggest that this feature could be interrelated with the degree of underweight and/or malnutrition.

  4. National Aeronautics and Space Administration NaNotechNology Roadmap

    E-print Network

    Waliser, Duane E.

    National Aeronautics and Space Administration · NaNotechNology Roadmap Technology Area 10 Michael A: Nanotechnology. NASA developed this DRAFT Space Technology Roadmap for use by the National Research Council (NRC Nanotechnology involves the manipulation of matter at the atomic level, where convention- al physics breaks down

  5. Regulation of intracellular Na+ in health and disease: pathophysiological mechanisms and implications for treatment

    PubMed Central

    Coppini, Raffaele; Ferrantini, Cecilia; Mazzoni, Luca; Sartiani, Laura; Olivotto, Iacopo; Poggesi, Corrado; Cerbai, Elisabetta; Mugelli, Alessandro

    2013-01-01

    Transmembrane sodium (Na+) fluxes and intracellular sodium homeostasis are central players in the physiology of the cardiac myocyte, since they are crucial for both cell excitability and for the regulation of the intracellular calcium concentration. Furthermore, Na+ fluxes across the membrane of mitochondria affect the concentration of protons and calcium in the matrix, regulating mitochondrial function. In this review we first analyze the main molecular determinants of sodium fluxes across the sarcolemma and the mitochondrial membrane and describe their role in the physiology of the healthy myocyte. In particular we focus on the interplay between intracellular Ca2+ and Na+. A large part of the review is dedicated to discuss the changes of Na+ fluxes and intracellular Na+ concentration([Na+]i) occurring in cardiac disease; we specifically focus on heart failure and hypertrophic cardiomyopathy, where increased intracellular [Na+]i is an established determinant of myocardial dysfunction. We review experimental evidence attributing the increase of [Na+]i to either decreased Na+ efflux (e.g. via the Na+/K+ pump) or increased Na+ influx into the myocyte (e.g. via Na+ channels). In particular, we focus on the role of the “late sodium current” (INaL), a sustained component of the fast Na+ current of cardiac myocytes, which is abnormally enhanced in cardiac diseases and contributes to both electrical and contractile dysfunction. We analyze the pathophysiological role of INaL enhancement in heart failure and hypertrophic cardiomyopathy and the consequences of its pharmacological modulation, highlighting the clinical implications. The central role of Na+ fluxes and intracellular Na+ physiology and pathophysiology of cardiac myocytes has been highlighted by a large number of recent works. The possibility of modulating Na+ inward fluxes and [Na+]i with specific INaL inhibitors, such as ranolazine, has made Na+a novel suitable target for cardiac therapy, potentially capable of addressing arrhythmogenesis and diastolic dysfunction in severe conditions such as heart failure and hypertrophic cardiomyopathy. PMID:24689024

  6. Light-driven Na(+) pump from Gillisia limnaea: a high-affinity Na(+) binding site is formed transiently in the photocycle.

    PubMed

    Balashov, Sergei P; Imasheva, Eleonora S; Dioumaev, Andrei K; Wang, Jennifer M; Jung, Kwang-Hwan; Lanyi, Janos K

    2014-12-01

    A group of microbial retinal proteins most closely related to the proton pump xanthorhodopsin has a novel sequence motif and a novel function. Instead of, or in addition to, proton transport, they perform light-driven sodium ion transport, as reported for one representative of this group (KR2) from Krokinobacter. In this paper, we examine a similar protein, GLR from Gillisia limnaea, expressed in Escherichia coli, which shares some properties with KR2 but transports only Na(+). The absorption spectrum of GLR is insensitive to Na(+) at concentrations of ?3 M. However, very low concentrations of Na(+) cause profound differences in the decay and rise time of photocycle intermediates, consistent with a switch from a "Na(+)-independent" to a "Na(+)-dependent" photocycle (or photocycle branch) at ?60 ?M Na(+). The rates of photocycle steps in the latter, but not the former, are linearly dependent on Na(+) concentration. This suggests that a high-affinity Na(+) binding site is created transiently after photoexcitation, and entry of Na(+) from the bulk to this site redirects the course of events in the remainder of the cycle. A greater concentration of Na(+) is needed for switching the reaction path at lower pH. The data suggest therefore competition between H(+) and Na(+) to determine the two alternative pathways. The idea that a Na(+) binding site can be created at the Schiff base counterion is supported by the finding that upon perturbation of this region in the D251E mutant, Na(+) binds without photoexcitation. Binding of Na(+) to the mutant shifts the chromophore maximum to the red like that of H(+), which occurs in the photocycle of the wild type. PMID:25375769

  7. Semi-volatiles at Mercury: Sodium (Na) and potassium (K)

    NASA Technical Reports Server (NTRS)

    Sprague, A.

    1994-01-01

    Several lines of evidence now suggest that Mercury is a planet rich in moderately-volatile elements such as Na and K. Recent mid-infrared spectral observations of Mercury's equatorial and mid-latitude region near 120 degrees mercurian longitude indicate the presence of plagioclase feldspar. Spectra of Mercury's surface exhibit spectral activity similar to labradorite (plagioclase feldspar with NaAlSi3O8: 30-50 percent) and bytownite (NaAlSi3O8: 10-30 percent). These surface studies were stimulated by the relatively large abundance of Na and K observed in Mercury's atmosphere. An enhanced column of K is observed at the longitudes of Caloris Basin and of the antipodal terrain. Extreme heating at these 'hot' longitudes and severe fracturing suffered from the large impact event could lead to enhanced outgassing from surface or subsurface materials. Alternatively, sputtering from a surface enriched in K could be the source of the observed enhancement. Recent microwave measurements of Mercury also give indirect evidence of a mercurian regolith less FeO-rich than the Moon. An anomalously high index of refraction derived from the whole-disk integrated phase curve of Danjon may also be indicative of surface sulfides contributing to a regolith that is moderately volatile-rich. The recent exciting observations of radar-bright spots at high latitudes also indicate that a substance of high volume scattering, like ice, is present in shadowed regions. Other radar-bright spots have been seen at locations of Na enhancements on the atmosphere. All combined, these pieces of evidence point to a planet that is not severely depleted in volatiles or semi-volatiles.

  8. Expression of epithelial Na channels in Xenopus oocytes

    PubMed Central

    1990-01-01

    Epithelial Na channel activity was expressed in oocytes from Xenopus laevis after injection of mRNA from A6 cells, derived from Xenopus kidney. Poly A(+) RNA was extracted from confluent cell monolayers grown on either plastic or permeable supports. 1-50 ng RNA was injected into stage 5-6 oocytes. Na channel activity was assayed as amiloride- sensitive current (INa) under voltage-clamp conditions 1-3 d after injection. INa was not detectable in noninjected or water-injected oocytes. This amiloride-sensitive pathway induced by the mRNA had a number of characteristics in common with that in epithelial cells, including (a) high selectivity for Na over K, (b) high sensitivity to amiloride with an apparent K1 of approximately 100 nM, (c) saturation with respect to external Na with an apparent Km of approximately 10 mM, and (d) a time-dependent activation of current with hyperpolarization of the oocyte membrane. Expression of channel activity was temperature dependent, being slow at 19 degrees C but much more rapid at 25 degrees C. Fractionation of mRNA on a sucrose density gradient revealed that the species of RNA inducing channel activity had a sedimentation coefficient of approximately 17 S. Treatment of filter-grown cells with 300 nM aldosterone for 24 h increased Na transport in the A6 cells by up to fivefold but did not increase the ability of mRNA isolated from those cells to induce channel activity in oocytes. The apparent abundance of mRNA coding for channel activity was 10-fold less in cells grown on plastic than in those grown on filters, but was increased two- to threefold by aldosterone. PMID:2170563

  9. Na0.44MnO2 nanorods as a cathode material for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Avci, Sevda; Oz, Erdinc; Demirel, Serkan; Altin, Emine; Altin, Serdar; Bayri, Ali; Yakinci, Eyyuphan

    2014-03-01

    Lithium-ion batteries have dominated the rechargeable battery market because of their high energy and power capability. On the other hand, sodium is one of the more abundant elements on Earth unlike Li. Moreover, Na has similar chemical properties to Li, indicating that Na-ion batteries can be an alternative to Li counterparts. With that respect, we have synthesized Na0.44MnO2 nanorods as cathode materials for Na-ion batteries. We have investigated the effects of structural, electrical, and magnetic properties on battery performance. We report the synthesis conditions and growth mechanism of the nanorods. The structure and the morphology of the materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and atomic force microscopy (AFM) techniques. Temperature dependent structural changes were determined via in situ X-ray diffraction and TG-DTA measurements showing structural changes above room temperature. This work is funded by The Scientific and Technological Research Council of Turkey with Grant No:112M487.

  10. Hermen àutica objetiva? e sua apropria Ô úo na pesquisa emp §rica na írea da educa Ô úo

    Microsoft Academic Search

    Rita Amelia Teixeira Vilela; Juliane Noack-Napoles

    2010-01-01

    Este texto apresenta a metodologia de pesquisa social qualitativa denominada ?hermen àutica objetiva? desenvolvida pelo soci logo alem úo Ulrich Oeverman e aponta sua propriedade na pesquisa educacional. Derivada da tradi Ô úo interpretativa da Teoria Cr §tica de Theodor Adorno, a finalidade da an ílise ?hermen àutica objetiva? ø descortinar a l gica entre as estruturas de reprodu Ô

  11. Valence and excited dipole-bound states of polar diatomic anions: LiH -, LiF -, LiCl -, NaH -, NaF -, NaCl -, BeO -, and MgO -

    NASA Astrophysics Data System (ADS)

    Gutsev, Gennady L.; Nooijen, Marcel; Bartlett, Rodney J.

    1997-09-01

    Valence and excited states of the anions formed by the polar molecules LiH, LiF, LiCl, NaH, NaF, NaCl, BeO, and MgO are calculated by the recently developed electron-attachment equation-of-motion coupled-cluster (EA-EOMCC) method. The LiH -, NaH -, and LiF - anions are found to possess two excited dipole-bound states and the LiCl -, NaF -, NaCl -, BeO -, and MgO - anions have three excited dipole-bound states. The critical values of the dipole moment required to sustain the first, second, etc., excited state appears to be specific for each class of polar molecules.

  12. Genetic variation of the alpha subunit of the epithelial Na+ channel influences exhaled Na+ in healthy humans.

    PubMed

    Foxx-Lupo, William T; Wheatley, Courtney M; Baker, Sarah E; Cassuto, Nicholas A; Delamere, Nicholas A; Snyder, Eric M

    2011-12-15

    Epithelial Na(+) channels (ENaC) are located in alveolar cells and are important in ?(2)-adrenergic receptor-mediated lung fluid clearance through the removal of Na(+) from the alveolar airspace. Previous work has demonstrated that genetic variation of the alpha subunit of ENaC at amino acid 663 is important in channel function: cells with the genotype resulting in alanine at amino acid 663 (A663) demonstrate attenuated function when compared to genotypes with at least one allele encoding threonine (T663, AT/TT). We sought to determine the influence of genetic variation at position 663 of ENaC on exhaled Na(+) in healthy humans. Exhaled Na(+) was measured in 18 AA and 13 AT/TT subjects (age=27±8 years vs. 30±10 years; ht.=174±12 cm vs. 171±10 cm; wt.=68±12 kg vs. 73±14 kg; BMI=22±3 kg/m(2) vs. 25±4 kg/m(2), mean±SD, for AA and AT/TT, respectively). Measurements were made at baseline and at 30, 60 and 90 min following the administration of a nebulized ?(2)-agonist (albuterol sulfate, 2.5 mg diluted in 3 ml normal saline). The AA group had a higher baseline level of exhaled Na(+) and a greater response to ?(2)-agonist stimulation (baseline=3.1±1.8 mmol/l vs. 2.3±1.5 mmol/l; 30 min-post=2.1±0.7 mmol/l vs. 2.2±0.8 mmol/l; 60 min-post=2.0±0.5 mmol/l vs. 2.3±1.0 mmol/l; 90 min-post=1.8±0.8 mmol/l vs. 2.6±1.5 mmol/l, mean±SD, for AA and AT/TT, respectively, p<0.05). The results are consistent with the notion that genetic variation of ENaC influences ?(2)-adrenergic receptor stimulated Na(+) clearance in the lungs, as there was a significant reduction in exhaled Na(+) over time in the AA group. PMID:21889619

  13. Renal brush-border membrane Na(+)-sulfate cotransport: stimulation by thyroid hormone.

    PubMed

    Tenenhouse, H S; Lee, J; Harvey, N

    1991-09-01

    The present study was undertaken to examine the interaction of phosphonoformic acid (PFA) with the Na(+)-sulfate cotransporter and the effect of thyroid hormone (triiodothyronine; T3) on Na(+)-dependent sulfate transport and Na(+)-dependent PFA binding in mouse renal brush-border membrane vesicles. PFA inhibits Na(+)-dependent sulfate transport in a competitive manner [apparent inhibitory constant (Ki) = 4.3 +/- 1.1 mM]. T3 administered in pharmacological doses significantly stimulates Na(+)-dependent sulfate transport in renal brush-border membranes compared with vehicle-treated controls. Although T3 has no effect on Na(+)-dependent glucose transport, T3 also stimulates Na(+)-dependent phosphate transport. Kinetic studies demonstrate that T3 increases the apparent maximal velocity (Vmax) for Na(+)-sulfate cotransport without changing the apparent Michaelis constant (Km). T3 does not significantly affect either Na(+)-dependent PFA binding or the phosphate- and sulfate-displaceable components of Na(+)-dependent PFA binding. Finally, Na(+)-dependent brush-border membrane sulfate transport is unchanged in phosphate-deprived mice that exhibit increased Na(+)-phosphate cotransport and in X-linked Hyp mice that exhibit impaired Na(+)-phosphate cotransport. The present results demonstrate that 1) PFA is a competitive inhibitor of Na(+)-sulfate cotransport, 2) T3 stimulates Na(+)-dependent sulfate, as well as Na(+)-dependent phosphate transport, but has no effect on PFA binding, and 3) phosphate deprivation and the X-linked Hyp mutation do not influence Na(+)-sulfate cotransport.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1832265

  14. Thyroid hormones increase Na+-H+ exchange activity in renal brush border membranes.

    PubMed Central

    Kinsella, J; Sacktor, B

    1985-01-01

    Na+-H+ exchange activity, i.e., amiloride-sensitive Na+ and H+ flux, in renal proximal tubule brush border (luminal) membrane vesicles was increased in the hyperthyroid rat and decreased in the hypothyroid rat, relative to the euthyroid animal. A positive correlation was found between Na+-H+ exchange activity and serum concentrations of thyroxine (T4) and triiodothyronine (T3). The thyroid status of the animal did not alter amiloride-insensitive Na+ uptake. The rate of passive pH gradient dissipation was higher in membrane vesicles from hyperthyroid rats compared to the rate in vesicles from hypothyroid animals, a result which would tend to limit the increase in Na+ uptake in vesicles from hyperthyroid animals. Na+-dependent phosphate uptake was increased in membrane vesicles from hyperthyroid rats; Na+-dependent D-glucose and L-proline uptakes were not changed by the thyroid status of the animal. The effect of thyroid hormones in increasing the uptake of Na+ in the brush border membrane vesicle is consistent with the action of the hormones in enhancing renal Na+ reabsorption. Further, the regulation of transtubular Na+ flux has now been shown to be concomitant with modulation of the entry of Na+ into the tubular cell across its luminal membrane, mediated by the exchange reaction, and with the previously reported control of the pumping of Na+ out of the cell across its basolateral membrane, mediated by the Na+,K+-ATPase. PMID:2987936

  15. Validation of estimating food intake in gray wolves by 22Na turnover

    USGS Publications Warehouse

    DelGiudice, G.D.; Duquette, L.S.; Seal, U.S.; Mech, L.D.

    1991-01-01

    We studied 22sodium (22Na) turnover as a means of estimating food intake in 6 captive, adult gray wolves (Canis lupus) (2 F, 4 M) over a 31-day feeding period. Wolves were fed white-tailed deer (Odocoileus virginianus) meat only. Mean mass-specific exchangeable Na pool was 44.8 .+-. 0.7 mEq/kg; there was no differeence between males and females. Total exchangeable Na was related (r2 = 0.85, P < 0.009) to body mass. Overall, 22Na turnover overestimated Na intake by 9.8 .+-. 2.4% after 32 days. Actual Na intake was similar in males and females; however, Na turnover (P < 0.05) and the discrepancy (P < 0.01) between turnover and actual Na intake were greater in females than males. From Day 8 to the end of the study, the absolute difference (mEq) between Na intake and Na turnover remained stable. Sodium turnover (mEq/kg/day) was a reliable (r2 = 0.91, P < 0.001) estimator of food consumption (g/kg/day) in wolves over a 32-day period. Sampling blood and weighing wolves every 1-4 days permitted identification of several potential sources of error, including changes in size of exchangeable Na pools, exchange of 22Na with gastrointestinal and bone Na, and rapid loss of the isotope by urinary excretion.

  16. Hygroscopic properties of NaCl and NaNO3 mixture particles as reacted inorganic sea-salt aerosol surrogates

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Kim, H.; Park, G.; Li, X.; Eom, H.-J.; Ro, C.-U.

    2014-12-01

    NaCl in fresh sea-salt aerosol (SSA) particles can partially or fully react with atmospheric NOx / HNO3, so internally mixed NaCl and NaNO3 aerosol particles can co-exist over a wide range of mixing ratios. Laboratory-generated, micrometer-sized NaCl and NaNO3 mixture particles at ten mixing ratios (mole fractions of NaCl (XNaCl) = 0.1 to 0.9) were examined systematically to observe their hygroscopic behavior, derive experimental phase diagrams for deliquescence and efflorescence, and understand the efflorescence mechanism. During the humidifying process, aerosol particles with the eutonic composition (XNaCl = 0.38) showed only one phase transition at their mutual deliquescence relative humidity (MDRH) of 67.9(± 0.5)%. On the other hand, particles with other mixing ratios showed two distinct deliquescence transitions, i.e., the eutonic component dissolved at MDRH and the remainder in the solid phase dissolved completely at their DRHs depending on the mixing ratios, resulting in a phase diagram composed of four different phases, as predicted thermodynamically. During the dehydration process, NaCl-rich particles (XNaCl > 0.38) showed two-stage efflorescence transitions: the first stage was purely driven by the homogeneous nucleation of NaCl and the second stage at the mutual efflorescence RH (MERH) of the eutonic components, with values in the range of 30.0-35.5%. Interestingly, aerosol particles with the eutonic composition (XNaCl = 0.38) also showed two-stage efflorescence with NaCl crystallizing first followed by heterogeneous nucleation of the remaining NaNO3 on the NaCl seeds. NaNO3-rich particles XNaCl ? 0.3) underwent single-stage efflorescence transitions at ERHs progressively lower than the MERH, because of the homogeneous nucleation of NaCl and the almost simultaneous heterogeneous nucleation of NaNO3 on the NaCl seeds. SEM/EDX elemental mapping indicated that the effloresced NaCl-NaNO3 particles at all mixing ratios were composed of a homogeneously crystallized NaCl moiety in the center, surrounded either by the eutonic component (for XNaCl > 0.38) or NaNO3 (for XNaCl ? 0.38). During the humidifying or dehydration process, the amount of eutonic composed part drives particle/droplet growth or shrinkage at the MDRH or MERH (second ERH), respectively, and the amount of remnant pure salts (NaCl or NaNO3 in NaCl- or NaNO3-rich particles, respectively) drives the second DRHs or first ERHs, respectively. Therefore, their behavior can be a precursor to the optical properties and direct radiative forcing for these atmospherically relevant mixture particles representing the coarse, reacted inorganic SSAs. In addition, the NaCl-NaNO3 mixture aerosol particles can maintain an aqueous phase over a wider RH range than the genuine SSA surrogate (i.e., pure NaCl particles), making their heterogeneous chemistry more probable.

  17. Hygroscopic properties of NaCl and NaNO3 mixture particles as reacted inorganic sea-salt aerosol surrogates

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Kim, H.; Park, G.; Li, X.; Eom, H.-J.; Ro, C.-U.

    2015-03-01

    NaCl in fresh sea-salt aerosol (SSA) particles can partially or fully react with atmospheric NOx/HNO3, so internally mixed NaCl and NaNO3 aerosol particles can co-exist over a wide range of mixing ratios. Laboratory-generated, micrometer-sized NaCl and NaNO3 mixture particles at 10 mixing ratios (mole fractions of NaCl (XNaCl) = 0.1 to 0.9) were examined systematically to observe their hygroscopic behavior, derive experimental phase diagrams for deliquescence and efflorescence, and understand the efflorescence mechanism. During the humidifying process, aerosol particles with the eutonic composition (XNaCl = 0.38) showed only one phase transition at their mutual deliquescence relative humidity (MDRH) of 67.9 (±0.5)% On the other hand, particles with other mixing ratios showed two distinct deliquescence transitions; i.e., the eutonic component dissolved at MDRH, and the remainder in the solid phase dissolved completely at their DRHs depending on the mixing ratios, resulting in a phase diagram composed of four different phases, as predicted thermodynamically. During the dehydration process, NaCl-rich particles (XNaCl > 0.38) showed a two stage efflorescence transition: the first stage was purely driven by the homogeneous nucleation of NaCl and the second stage at the mutual efflorescence RH (MERH) of the eutonic components, with values in the range of 30.0-35.5%. Interestingly, aerosol particles with the eutonic composition (XNaCl = 0.38) also showed two-stage efflorescence, with NaCl crystallizing first followed by heterogeneous nucleation of the remaining NaNO3 on the NaCl seeds. NaNO3-rich particles (XNaCl ? 0.3) underwent single-stage efflorescence transitions at ERHs progressively lower than the MERH because of the homogeneous nucleation of NaCl and the almost simultaneous heterogeneous nucleation of NaNO3 on the NaCl seeds. SEM/EDX elemental mapping indicated that the effloresced NaCl-NaNO3 particles at all mixing ratios were composed of a homogeneously crystallized NaCl moiety in the center, surrounded either by the eutonic component (for XNaCl > 0.38) or NaNO3 (for XNaCl ? 0.38). During the humidifying or dehydration process, the amount of eutonic composed part drives particle/droplet growth or shrinkage at the MDRH or MERH (second ERH), respectively, and the amount of pure salts (NaCl or NaNO3 in NaCl- or NaNO3-rich particles, respectively) drives the second DRHs or first ERHs, respectively. Therefore, their behavior can be a precursor to the optical properties and direct radiative forcing for these atmospherically relevant mixture particles representing the coarse, reacted inorganic SSAs. In addition, the NaCl-NaNO3 mixture aerosol particles can maintain an aqueous phase over a wider RH range than pure NaCl particles as SSA surrogate, making their heterogeneous chemistry more probable.

  18. [Effect of NaHCO3 stress on uptake and transportation of Na+, K+ and Ca2+ in three shrub species].

    PubMed

    Mao, Gui-Lian; Li, Guo-Qi; Xu, Xing; Zhang, Xin-Xue

    2014-03-01

    We detected absorption and transportation of ions in the leaves of Atriplex nummularia, Atriplex canescens and Lycium barbarum under NaHCO3 stress (300 mmol x L(-1)) by using atomic absorption spectrophotometry and non-invasive ion flux measurement. The results showed that leaves of the A. nummularia, A. canescens and L. barbarum exhibited a high capacity to induce the Na+ accumulation when compared with that of control. The higher the concentration of NaHCO3 treatment, the more Na+ accumulated in the leaves of the three plants under experimental condition. L. barbarum showed a higher Na+ efflux in the mesophyll cells, whereas A. nummularia and A. canescens showed a relative lower efflux. A lower K+ content and a higher Na+/K+ ratio were detected in leaves of A. nummularia and L. barbarum. However, a higher K+ content and a lower Na+/K+ ratio were seen in leaves of A. canescens. Due to induction of Ca2+ efflux under the NaHCO3 treatment, a lower Ca2+ content and a higher Na+/Ca2+ ratio were observed in L. barbarum. On the contrary, a higher Ca2+ influx was observed in A. nummularia and A. canescens. These results suggested that the three shrubs species had different Na+ segmentation strategies. The accumulation of Na+ inhibited Ca2+ absorption in leaves of L. barbarum, while in the A. nummularia and A. canescens, Ca2+ influx induced [Ca2+]cyt which preserved a less-depolarized PM and then inhibited K efflux. The maintaining of cellular K+/Na+ homeostasis in A. nummularia and A. canescens might be achieved by the induction of [Ca2+]cyt under the NaHCO3 treatment. PMID:24984488

  19. Crystal structure of new synthetic Ca,Na carbonate-borate Ca2Na(Na x Ca0.5 - x )[B{3/ t }B{2/?}O8(OH)(O1 - x OH x )](CO3)

    NASA Astrophysics Data System (ADS)

    Yamnova, N. A.; Borovikova, E. Yu.; Gurbanova, O. A.; Dimitrova, O. V.; Zubkova, N. V.

    2012-05-01

    New Ca,Na carbonate-borate Ca2Na(Na x Ca0.5 - x ) [B{3/ t }B{2/?}O8(OH)(O1 - x OH x )](CO3) crystals ( x ˜ 0.4) have been synthesized by the hydrothermal method in the Ca(OH)2-H3BO3-Na2CO3-NaCl-system at t = 250°C and P = 70-80 atm; the structure parameters are found to be a = 11.1848(3) Å, b = 6.4727(2) Å, c = 25.8181(7) Å, ? = 96.364(3)°, V = 1857.60(9) Å3, sp. gr. C2/ c, Z = 8, and ?calcd = 2.801 g/cm3 (Xcalibur S autodiffractometer (CCD), 2663 reflections with I > 2? ( I), direct solution, refinement by the least-squares method in the anisotropic approximation of thermal atomic vibrations, hydrogen localization, R 1 = 0.0387). The structure is based on boron-oxygen layers of pentaborate radicals 5(2? + 3T). Ca and Na polyhedra and CO3 triangles are located between the layers. A crystallochemical analysis of the new Ca,Na carbonate-borate has established its similarity to natural Na,Ca pentaborates (heidornite and tuzlaite) and synthetic Na,Ba-decaborate.

  20. Synthesis and characterization of sodium-titanium phosphates, Na4(TiO)(PO4)2, Na(TiO)PO4, and NaTi2(PO4)3

    Microsoft Academic Search

    Carlos E. Bamberger; George M. Begun; O. B. Cavin

    1988-01-01

    Experimental examination of part of the system Na2O-TiO2-P2O5 revealed the existence of two new sodium-titanium phosphates, Na4(TiO)(PO4)2 and Na(TiO)PO4. Their synthesis was accomplished by several different reactions and their identity was established by means of Raman spectroscopy and X-ray diffraction. Additionally, novel reactions for the synthesis of NaTi2(PO4)3 have been demonstrated.

  1. Synthesis and characterization of sodium-titanium phosphates, Na/sub 4/(TiO)(PO/sub 4/)/sub 2/, Na(TiO)PO/sub 4/, and NaTi/sub 2/(PO/sub 4/)/sub 3/*

    SciTech Connect

    Bamberger, C.E.; Begun, G.E.; Cavin, O.B.

    1988-04-01

    Experimental examination of part of the system Na/sub 2/O-TiO/sub 2/-P/sub 2/O/sub 5/ revealed the existence of two new sodium-titanium phosphates, Na(TiO)(PO)/sub 4/ and Na(TiO)P)/sub 4/. Their synthesis was accomplished by several different reactions and their identity was established by means of Raman spectroscopy and X-ray diffraction. Additionally, novel reactions for the synthesis of NaTi/sub 2/(PO/sub 4/)/sub 3/ have been demonstrated.

  2. Heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(s)

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun; Timonen, Raimo S.; Keyser, Leon F.; Yung, Yuk L.

    1995-01-01

    The heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) (eq 1) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(S) (eq 2) were investigated over the temperature range 223-296 K in a flow-tube reactor coupled to a quadrupole mass spectrometer. Either a chemical ionization mass spectrometer (CIMS) or an electron-impact ionization mass spectrometer (EIMS) was used to provide suitable detection sensitivity and selectivity. In order to mimic atmospheric conditions, partial pressures of HNO3 and N2O5 in the range 6 x 10(exp -8) - 2 x 10(exp -6) Torr were used. Granule sizes and surface roughness of the solid NaCl substrates were determined by using a scanning electron microscope. For dry NaCl substrates, decay rates of HNO3 were used to obtain gamma(1) = 0.013 +/- 0.004 (1sigma) at 296 K and > 0.008 at 223 K, respectively. The error quoted is the statistical error. After all corrections were made, the overall error, including systematic error, was estimated to be about a factor of 2. HCl was found to be the sole gas-phase product of reaction 1. The mechanism changed from heterogeneous reaction to predominantly physical adsorption when the reactor was cooled from 296 to 223 K. For reaction 2 using dry salts, gamma(2) was found to be less than 1.0 x 10(exp -4) at both 223 and 296 K. The gas-phase reaction product was identified as ClNO2 in previous studies using an infrared spectrometer. An enhancement in reaction probability was observed if water was not completely removed from salt surfaces, probably due to the reaction of N2O5(g) + H2O(s) yields 2HNO3(g). Our results are compared with previous literature values obtained using different experimental techniques and conditions. The implications of the present results for the enhancement of the hydrogen chloride column density in the lower stratosphere after the El Chichon volcanic eruption and for the chemistry of HCl and HNO3 in the marine troposphere are discussed.

  3. Grant Title: HEWLETT FOUNDATION EDUCATION PROGRAM Funding Opportunity Number: N/A

    E-print Network

    Farritor, Shane

    are awarded to organizations by invitation. Amount: N/A Length of Support: N/A Eligible Applicants: Non-profit organizations, higher education institutions, school districts. Summary: The Hewlett Foundation makes grants

  4. Grant Title: POSTDOCTORAL FELLOWSHIP IN MENTAL HEALTH AND SUBSTANCE ABUSE SERVICES Funding Opportunity Number: NA

    E-print Network

    Farritor, Shane

    Grant Title: POSTDOCTORAL FELLOWSHIP IN MENTAL HEALTH AND SUBSTANCE ABUSE SERVICES (MHSAS) Funding Opportunity Number: NA Agency/Department: American Psychological Association (APA), Substance Abuse and Mental health and substance abuse services and research. Release and Expiration: NA Application Deadline

  5. Na+ accumulation in root symplast of sunflower plants exposed to moderate salinity is transpiration-dependent.

    PubMed

    Quintero, José Manuel; Fournier, José María; Benlloch, Manuel; Rodríguez-Navarro, Alonso

    2008-08-25

    Twenty-day-old sunflower plants (Helianthus annuus L. cv Sun-Gro 380) grown hydroponically under controlled conditions were used to study the effect of transpiration on Na(+) compartmentalization in roots. The plants were exposed to low Na(+) concentrations (25 mM NaCl) and different environmental humidity conditions over a short time period (8.5 h). Under these conditions, Na(+) was accumulated primarily in the root, but only the Na(+) accumulated in the root symplast was dependent on transpiration, while the Na(+) accumulated in both the shoot and the root apoplast exhibited a low transpiration dependence. Moreover, Na(+) content in the root apoplast was reached quickly (0.25 h) and increased little with time. These results suggest that, in sunflower plants under moderate salinity conditions, Na(+) uptake in the root symplast is mediated by a transport system whose activity is enhanced by transpiration. PMID:18166246

  6. Caustic Recycle from Hanford Tank Waste Using Large Area NaSICON Structures (LANS)

    SciTech Connect

    Fountain, Matthew S.; Sevigny, Gary J.; Balagopal, S.; Bhavaraju, S.

    2009-03-31

    This report presents the results of a 5-day test of an electrochemical bench-scale apparatus using a proprietary (NAS-GY) material formulation of a (Na) Super Ion Conductor (NaSICON) membrane in a Large Area NaSICON Structures (LANS) configuration. The primary objectives of this work were to assess system performance, membrane seal integrity, and material degradation while removing Na from Group 5 and 6 tank waste from the Hanford Site.

  7. Membrane Na+-pyrophosphatases Can Transport Protons at Low Sodium Concentrations*

    PubMed Central

    Luoto, Heidi H.; Nordbo, Erika; Baykov, Alexander A.; Lahti, Reijo; Malinen, Anssi M.

    2013-01-01

    Membrane-bound Na+-pyrophosphatase (Na+-PPase), working in parallel with the corresponding ATP-energized pumps, catalyzes active Na+ transport in bacteria and archaea. Each ?75-kDa subunit of homodimeric Na+-PPase forms an unusual funnel-like structure with a catalytic site in the cytoplasmic part and a hydrophilic gated channel in the membrane. Here, we show that at subphysiological Na+ concentrations (<5 mm), the Na+-PPases of Chlorobium limicola, four other bacteria, and one archaeon additionally exhibit an H+-pumping activity in inverted membrane vesicles prepared from recombinant Escherichia coli strains. H+ accumulation in vesicles was measured with fluorescent pH indicators. At pH 6.2–8.2, H+ transport activity was high at 0.1 mm Na+ but decreased progressively with increasing Na+ concentrations until virtually disappearing at 5 mm Na+. In contrast, 22Na+ transport activity changed little over a Na+ concentration range of 0.05–10 mm. Conservative substitutions of gate Glu242 and nearby Ser243 and Asn677 residues reduced the catalytic and transport functions of the enzyme but did not affect the Na+ dependence of H+ transport, whereas a Lys681 substitution abolished H+ (but not Na+) transport. All four substitutions markedly decreased PPase affinity for the activating Na+ ion. These results are interpreted in terms of a model that assumes the presence of two Na+-binding sites in the channel: one associated with the gate and controlling all enzyme activities and the other located at a distance and controlling only H+ transport activity. The inherent H+ transport activity of Na+-PPase provides a rationale for its easy evolution toward specific H+ transport. PMID:24158447

  8. Mechanisms of coronary vasoconstriction induced by Na arachidonate in experimentally diabetic dogs

    Microsoft Academic Search

    L. Sterin-Borda; E. Borda; E. J. del Castillo; M. F. Gimeno; A. L. Gimeno

    1982-01-01

    Summary Na arachidonate (NaA) enhanced the resting basal tone of isolated coronary arteries from diabetic dogs and depressed it in coronary arteries from normal controls. Inhibitors of thromboxane A2 biosynthesis and of lipoxygenases abolished the vasoconstrictor effect of NaA on diabetic arteries, whereas inhibitors of cyclooxygenase activity and PGI2 biosynthesis blocked the vasodilating action of NaA on normal arteries.

  9. Function and presumed molecular structure of Na + -D-glucose cotransport systems

    Microsoft Academic Search

    H. Koepsell; J. Spangenberg

    1994-01-01

    Functional characterization of Na+-d-glucose cotransport in intestine and kidney indicates the existence of heterogeneous Na+-d-glucose cotransport systems. Target size analysis of the transporting unit and model analysis of substrate binding have been performed and proteins have been cloned which mediate (SGLT1) and modulate (RS1) the expression of Na+-d-glucose cotransport. The experiments support the hypothesis that functional Na+-d-glucose cotransport systems in

  10. A new polymer electrolyte system (PEO) n :NaPO 3

    Microsoft Academic Search

    Amrtha Bhide; K. Hariharan

    2006-01-01

    A new Na+ ion conducting polymer electrolyte, based on poly(ethylene oxide) (PEO) and sodium meta phosphate (NaPO3) is investigated. (PEO)n:NaPO3 polymer metal salt complexes with different [ethylene oxide]\\/Na ratios (n=3, 4, 6, 8 and 10) are prepared by the solution casting method. Dissolution of the salt into the polymer host is confirmed by X-ray diffraction, differential scanning calorimetry (DSC) and

  11. Hofmeister effects of anions on the kinetics of partial reactions of the Na+,K+-ATPase.

    PubMed Central

    Ganea, C; Babes, A; Lüpfert, C; Grell, E; Fendler, K; Clarke, R J

    1999-01-01

    The effects of lyotropic anions, particularly perchlorate, on the kinetics of partial reactions of the Na+,K+-ATPase from pig kidney were investigated by two different kinetic techniques: stopped flow in combination with the fluorescent label RH421 and a stationary electrical relaxation technique. It was found that 130 mM NaClO4 caused an increase in the Kd values of both the high- and low-affinity ATP-binding sites, from values of 7.0 (+/- 0.6) microM and 143 (+/- 17) microM in 130 mM NaCl solution to values of 42 (+/- 3) microM and 660 (+/- 100) microM in 130 mM NaClO4 (pH 7.4, 24 degrees C). The half-saturating concentration of the Na+-binding sites on the E1 conformation was found to decrease from 8-10 mM in NaCl to 2.5-3.5 mM in NaClO4 solution. The rate of equilibration of the reaction, E1P(Na+)3 left arrow over right arrow E2P + 3Na+, decreased from 393 (+/- 51) s-1 in NaCl solution to 114 (+/- 15) s-1 in NaClO4. This decrease is attributed predominantly to an inhibition of the E1P(Na+)3 --> E2P(Na+)3 transition. The effects can be explained in terms of electrostatic interactions due to perchlorate binding within the membrane and/or protein matrix of the Na+,K+-ATPase membrane fragments and alteration of the local electric field strength experienced by the protein. The kinetic results obtained support the conclusion that the conformational transition E1P(Na+)3 --> E2P(Na+)3 is a major charge translocating step of the pump cycle. PMID:10388756

  12. An ab initio study of dissociative electron attachment to NaHCO3 and NaCO3, and the role of these reactions in the formation of sudden sodium layers

    Microsoft Academic Search

    B. Rajasekhar; John M. C. Plane

    1993-01-01

    One of the mechanisms that has been proposed to explain the phenomenon of sudden sodium layers (SSLs) in the upper atmosphere is dissociative attachment of electrons to sodium compounds such as NaHCO3 and NaCO3. In this study, abinitio calculations have been used to estimate the reaction enthalpies (?H°0(NaX + e? ? Na + X?)) for NaHCO3 and NaCO3, which are

  13. Casos de Estudo com a Bolsa de Objectos de Aprendizagem: Anlise na Perspectiva da Computao

    E-print Network

    da Silva, Alberto Rodrigues

    propor o sistema BOA (Bolsa de Objectos de Aprendizagem) como uma plataforma de Objectos de Aprendizagem, classificações, experiências educativas assim aumentando o valor inerente de cada objecto. Este artigo introduz Ensino e Aprendizagem, Plataformas Colaborativas, Computação Social. 1. INTRODUÇÃO A popularidade dos

  14. Swing curve measurement and simulation for high NA lithography

    NASA Astrophysics Data System (ADS)

    Bauer, J.; Haak, U.; Schulz, K.; Old, G.; Kraft, A.

    2006-03-01

    In this paper, we will present a new swing curve measurement and simulation method. Swing curve measurements were completed using a high NA KrF Scanner (Nikon S207D) where illumination and reflectance sensors were utilised to measure the reflectivity of the total wafer stack. With this new method, the influence of the full illumination NA ill (including effects of polarized illumination and immersion lenses), as well as the substrate properties can be taken into account. A new software has been developed to calculate the swing curve for a film stack of multiple layers on any given substrate, taking into account incident light integration over the whole aperture of the lithography tool objectives. The software also covers diffraction effects and their influences upon the swing. We will demonstrate, that with this new method, even mask diffraction effects can be described allowing a final and more accurate calculation and optimisation of the swing effect.

  15. Infrared reflectance spectra of Na2S with contaminant Na2CO3 - Effects of adsorbed H2O and CO2 and relation to studies of Io

    NASA Astrophysics Data System (ADS)

    Nash, D. B.

    1988-05-01

    A previously published IR reflectance spectrum of Na2S, a candidate surface component on Jupiter's satellite Io, showed a weak but distinct band at approximately 4.04 ?m that was interpreted as due to chemisorbed H2S or SO2. New spectra have been obtained on Na2S powder showing that this 4-?m band is not due to H2S or SO2, but rather Na2CO3, a contaminant present in the original material. Because of the extreme hygroscopic nature of Na2S, a reflectance spectrum of pure Na2S is not yet available. But the apparent high IR brightness of Na2S and the spectral neutrality in the range 1 - 5 ?m suggest that it could be a component on Io's surface.

  16. Intersubunit bridging by Na+ ions as a rationale for the unusual stability of the c-rings of Na+-translocating F1F0 ATP synthases.

    PubMed

    Meier, Thomas; Dimroth, Peter

    2002-11-01

    The oligomeric c-rings of Na+-translocating F1F0 ATP synthases exhibit unusual stability, resisting even boiling in SDS. Here, we show that the molecular basis for this remarkable property is intersubunit crossbridging by Na+ or Li+ ions. The heat stability of c11 was dependent on the presence of Na+ or Li+ ions. For equal stability, 10 times higher Li+ than Na+ concentrations were required, reflecting the 10 times lower binding affinity for Li+ than for Na+. In a recent structural model of c11, the Na+ or Li+ binding ligands are located on neighboring c-subunits, which thus become crossbridged by the binding of either alkali ion with a concomitant increase in the stability of the ring. Site-directed mutagenesis strengthens the essential role of glutamate 65 in the crossbridging of the subunits and also corroborates the proposed stabilizing effect of an ion bridge including aspartate 2. PMID:12393753

  17. Na8Au9.8(4)Ga7.2 and Na17Au5.87(2)Ga46.63: The diversity of pseudo 5-fold symmetries in the Na-Au-Ga system

    NASA Astrophysics Data System (ADS)

    Smetana, Volodymyr; Corbett, John D.; Miller, Gordon J.

    2013-11-01

    The Na-rich part (~30% Na) of the Na-Au-Ga system between NaAu2, NaGa4, and Na22Ga39 has been found to contain the ternary phases Na8Au9.8(4)Ga7.2 (I) and Na17Au5.87(2)Ga46.63 (II), according to the results of single crystal X-ray diffraction measurements. I is orthorhombic, Cmcm, a=5.3040(1), b=24.519(5), c=14.573(3) Å, and contains a network of clusters with local 5-fold symmetry along the a-axis. Such clusters are frequent building units in decagonal quasicrystals and their approximants. II is rhombohedral, R3¯m, a=16.325(2), c=35.242(7) Å, and contains building blocks that are structurally identical to the Bergman-type clusters as well as fused icosahedral units known with active metals, triels and late transition elements. II also contains a polycationic network with elements of the clathrate V type structure. Tight-binding electronic structure calculations using linear muffin-tin-orbital (LMTO) methods on idealized models of I and II indicate that both compounds are metallic with evident pseudogaps at the corresponding Fermi levels. The overall Hamilton bond populations are generally dominated by Au-Ga and Au-Au bonds in I and by Ga-Ga bonds in II; moreover, the Na-Au and Na-Ga contributions in I are unexpectedly large, ~20% of the total. A similar involvement of sodium in covalent bonding has also been found in the electron-richer i-Na13Au12Ga15 quasicrystal approximant.

  18. The electroneutral Na+-(K+)Cl? cotransport family

    Microsoft Academic Search

    Steven C Hebert; Gerardo Gamba; Mark Kaplan

    1996-01-01

    The electroneutral Na+-(K+)-Cl? cotransport family. Recently the molecular identification of the major electroneutral sodium-potassium-chloride entry mechanisms present on apical membranes of distal nephron segments of the mammalian kidney, on basolateral membranes of many non-renal epithelial cells and on certain non-epithelial tissues has been achieved. These transporters represent a major pathway for cellular uptake of chloride critical for chloride absorptive and

  19. Protire?ivý vplyv WikiLeaks na diplomaciu

    Microsoft Academic Search

    Laura Meri?ková

    2012-01-01

    Cie?om práce je reagova? a prispie? k diskusii o zverejnení sto tisícky tajných depeší internetovým portálom Wikileaks, ktoré sa uskuto?nilo v roku 2010. ?lánok analyzuje dostupné názory a závery, ktoré prepája a na ich základe sa autor snaží zhodnoti?, aké dôsledky doposia? priniesla daná skuto?nos? v diplomacii ako i v spolo?nosti. ?alej autor využíva teoretické a empirické poznatky z odborných

  20. EFEITOS DA GEADA NA MADEIRA DE Eucalyptus saligna

    Microsoft Academic Search

    E. S. B. FERRAZ; A. R. COUTINHO

    RESUMO - Numa área de reflorestamento com Eucalyptus saligna com nove anos de idade foram selecionadas 235 árvores divididas em cinco classes de diâmetro, caracterizando toda a população. Segundo os registros meteorológicos, uma geada ocorreu no segundo ano ap6s o plantio. Procurou-se então verificar os efeitos da geada na madeira das árvores amostradas, procurando-se distinguir as dominantes das dominadas. As

  1. The local distribution of NA I interstellar gas

    Microsoft Academic Search

    B. Y. Welsh; N. Craig; P. W. Vedder; J. V. Vallerga

    1994-01-01

    We present high-resolution absorption measurements (lambda\\/Delta lambda approximately 75,000) of the interstellar Na I D lines at 5890 A toward 80 southern hemisphere early-type stars located in the local interstellar medium (LISM). Combining these results with other sodium measurements taken from the literature, we produce galactic maps of the distribution of neutral sodium column density for a total of 293

  2. Formaldehyde base catalysis by NaX zeolite

    Microsoft Academic Search

    S. Trigerman; E. Biron; A. H. Weiss

    1977-01-01

    Reactions of formaldehyde to produce formose sugars at 95°C in aqueous solutions were studied over a trickle bed of NaX Zeolite spheres. When effluent pH was in the range of 5 to 7, a rapid irreversible catalyst deactivation from an initial 50% conversion occurred. The catalyst was destroyed in less than five hours by formic acid produced by the undesired

  3. Incidentie recidiverende veneuze tromboembolie na staken behandeling met ximelagatran

    Microsoft Academic Search

    H. J. M. G. Nelissen-Vrancken

    2006-01-01

    Samenvatting  Patiënten met veneuze trombose worden in de acute fase behandeld met een direct werkend antitromboticum ter preventie van\\u000a progressie van de trombus en het ontstaan van longembolie. Daarna is gedurende ten minste zes maanden profylaxe met een oraal\\u000a anticoagulans noodzakelijk. Ximelagatran is een orale directe trombineremmer en wordt na orale absorptie omgezet in melagatran,\\u000a dat zowel vrij als gebonden trombine

  4. NEFUZIJSKA DINAMI?NA STABILIZACIJA PRI DEGENERATIVNIH OKVARAH LEDVENE HRBTENICE

    Microsoft Academic Search

    Gorazd Bunc

    Izhodiš?a S sodobnim na?inom življenja in s staranjem prebivalstva se delež degenerativnih bolezni ledvene hrbtenice nenehno pove?uje. Te bolezni predstavljajo velik odstotek obolevnosti aktivne populacije. Metode Do nedavnega so se pri zdravljenju degenerativnih sprememb uporabljale predvsem razli?ne tehnike rigidne fuzije, ki so strmele k trdni stabilizaciji okvarjenega segmenta. Te tehnike so pogosto vodile v dodatne degenerativne okvare sosednjih segmentov, zato

  5. Hygroscopic Growth and Deliquescence of NaCl Nanoparticles Mixed with Surfactant SDS Christopher W. Harmon,

    E-print Network

    Nizkorodov, Sergey

    as the effects of particle size and chemical composition on hygroscopic properties. NaCl has routinely been used water uptake on sodium chloride (NaCl) particles containing varying amounts of sodium dodecyl sulfateHygroscopic Growth and Deliquescence of NaCl Nanoparticles Mixed with Surfactant SDS Christopher W

  6. ROS-mediated vascular homeostatic control of root-to-shoot soil Na delivery in Arabidopsis

    PubMed Central

    Jiang, Caifu; Belfield, Eric J; Mithani, Aziz; Visscher, Anne; Ragoussis, Jiannis; Mott, Richard; Smith, J Andrew C; Harberd, Nicholas P

    2012-01-01

    Sodium (Na) is ubiquitous in soils, and is transported to plant shoots via transpiration through xylem elements in the vascular tissue. However, excess Na is damaging. Accordingly, control of xylem-sap Na concentration is important for maintenance of shoot Na homeostasis, especially under Na stress conditions. Here we report that shoot Na homeostasis of Arabidopsis thaliana plants grown in saline soils is conferred by reactive oxygen species (ROS) regulation of xylem-sap Na concentrations. We show that lack of A. thaliana respiratory burst oxidase protein F (AtrbohF; an NADPH oxidase catalysing ROS production) causes hypersensitivity of shoots to soil salinity. Lack of AtrbohF-dependent salinity-induced vascular ROS accumulation leads to increased Na concentrations in root vasculature cells and in xylem sap, thus causing delivery of damaging amounts of Na to the shoot. We also show that the excess shoot Na delivery caused by lack of AtrbohF is dependent upon transpiration. We conclude that AtrbohF increases ROS levels in wild-type root vasculature in response to raised soil salinity, thereby limiting Na concentrations in xylem sap, and in turn protecting shoot cells from transpiration-dependent delivery of excess Na. PMID:23064146

  7. Alteration of Na + currents in dorsal root ganglion neurons from rats with a painful neuropathy

    Microsoft Academic Search

    M. G Kral; Z Xiong; R. E Study

    1999-01-01

    Increased excitability of primary sensory neurons may be important for the generation of neuropathic pain from nerve injury. The currents underlying the action potentials of these neurons are largely carried by Na+, and changes in Na+ currents have been postulated to contribute to this increased excitability. Using patch clamp in whole-cell mode, we recorded Na+ currents from DRG neurons freshly

  8. Badania Ekologiczne Ryzyka Zachorowa? Na Kleszczowe Zapalenie Mózgu W Polsce-Omówienie Metody

    PubMed Central

    Stefanoff, Pawe?; Staszewska, Ewa; Ustrnul, Zbigniew; Rogalska, Justyna; ?ankiewicz, Aleksandra; Rosi?ska, Magdalena

    2009-01-01

    W pracy omówiono metodologi? aktualnie prowadzonych bada? ekologicznych kleszczowego zapalenia mózgu (kzm) na terenie Polski. W celu oceny wp?ywu zró?nicowanych czynników ?rodowiskowych, klimatycznych oraz spo?ecznych na wyst?powanie kzm w ró?nych regionach Polski zostanie przeprowadzona wieloczynnikoica analiza statystyczna na poziomie gmin dla lat 1999-2006. PMID:22320045

  9. Shoot Na+ Exclusion and Increased Salinity Tolerance Engineered by Cell TypeSpecific Alteration of

    E-print Network

    Haseloff, Jim

    Shoot Na+ Exclusion and Increased Salinity Tolerance Engineered by Cell Type­Specific Alteration, University of Adelaide, SA 5064, Australia Soil salinity affects large areas of cultivated land, causing of root-to-shoot transfer of Na+. Plants with reduced shoot Na+ also have increased salinity tolerance

  10. Biofunctionalization, cytotoxicity, and cell uptake of lanthanide doped hydrophobically ligated NaYF4 upconversion nanophosphors

    E-print Network

    Ju, Yiguang

    hexagonal phase NaYF4:Yb,Er upconversion nanophosphors UCNPs was achieved by introducing amino and carboxyl efficiency, and among them, hexagonal phase NaYF4 crystal in bulky state has been reported to be the most in the synthesis and physical studies of nanoscale NaYF4 based UCNPs via either hydro- thermal or cothermolysis

  11. High Resolution Structure of the Open NaK Channel

    PubMed Central

    Alam, Amer; Jiang, Youxing

    2008-01-01

    We report the crystal structure of the non-selective cation channel NaK from b. cereus at a resolution of 1.6 Å. The structure reveals the intracellular gate in an open state compared to the closed form reported previously, making NaK the only channel for which the three-dimensional structures of both conformations are known. Channel opening follows a conserved mechanism of inner helix bending utilizing a flexible glycine residue, the gating hinge, seen in MthK and most other tetrameric cation channels. Additionally, distinct inter and intra-subunit rearrangements involved in channel gating are seen and characterized for the first time along with inner helix twisting motions. Furthermore, we identify a residue deeper within the cavity of the channel pore, Phe92, which likely forms a constriction point within the open pore, restricting ion flux through the channel. Mutating this residue to Ala causes a subsequent increase in ion conduction rates as measured by 86Rb flux assays. The structures of both the open and closed conformations of the NaK channel correlate very well with those of equivalent K+ channel conformations, namely MthK and KcsA, respectively. PMID:19098917

  12. Rate of Homogeneous Crystal Nucleation in molten NaCl

    E-print Network

    Valeriani, C; Frenkel, D; 10.1063/1.1896348

    2009-01-01

    We report a numerical simulation of the rate of crystal nucleation of sodium chloride from its melt at moderate supercooling. In this regime nucleation is too slow to be studied with "brute-force" Molecular Dynamics simulations. The melting temperature of ("Tosi-Fumi") NaCl is $\\sim 1060$K. We studied crystal nucleation at $T$=800K and 825K. We observe that the critical nucleus formed during the nucleation process has the crystal structure of bulk NaCl. Interestingly, the critical nucleus is clearly faceted: the nuclei have a cubical shape. We have computed the crystal-nucleation rate using two completely different approaches, one based on an estimate of the rate of diffusive crossing of the nucleation barrier, the other based on the Forward Flux Sampling and Transition Interface Sampling (FFS-TIS) methods. We find that the two methods yield the same result to within an order of magnitude. However, when we compare the extrapolated simulation data with the only available experimental results for NaCl nucleatio...

  13. Benchmarking EUV mask inspection beyond 0.25 NA

    SciTech Connect

    Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno B.; Kemp, Charles D.; Huh, S.; Han, H.-S.; Naulleau, P.; Gunion, R.F.

    2008-09-18

    The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benchmarking tests show image contrast above 75% for 100-nm mask features, and significant improvements and across the full range of measured sizes. The zoneplate lens has been replaced by an array of user-selectable zoneplates with higher magnification and NA values up to 0.0875, emulating the spatial resolution of a 0.35-NA 4 x EUV stepper. Illumination uniformity is above 90% for mask areas 2-{micro}m-wide and smaller. An angle-scanning mirror reduces the high coherence of the synchrotron beamline light source giving measured {sigma} values of approximately 0.125 at 0.0875 NA.

  14. ?-Adducin Stimulates the Thiazide-sensitive NaCl Cotransporter

    PubMed Central

    Dimke, Henrik; San-Cristobal, Pedro; de Graaf, Mark; Lenders, Jacques W.; Deinum, Jaap; Hoenderop, Joost G.J.

    2011-01-01

    The thiazide-sensitive NaCl cotransporter (NCC) plays a key role in renal salt reabsorption and the determination of systemic BP, but the molecular mechanisms governing the regulation of NCC are not completely understood. Here, through pull-down experiments coupled to mass spectrometry, we found that ?-adducin interacts with the NCC transporter. ?-Adducin colocalized with NCC to the distal convoluted tubule. 22Na+ uptake experiments in the Xenopus laevis oocyte showed that ?-adducin stimulated NCC activity in a dose-dependent manner, an effect that occurred upstream from With No Lysine (WNK) 4 kinase. The binding site of ?-adducin mapped to the N terminus of NCC and encompassed three previously reported phosphorylation sites. Supporting this site of interaction, competition with the N-terminal domain of NCC abolished the stimulatory effect of ?-adducin on the transporter. ?-Adducin failed to increase NCC activity when these phosphorylation sites were constitutively inactive or active. In addition, ?-adducin bound only to the dephosphorylated N terminus of NCC. Taken together, our observations suggest that ?-adducin dynamically regulates NCC, likely by amending the phosphorylation state, and consequently the activity, of the transporter. These data suggest that ?-adducin may influence BP homeostasis by modulating renal NaCl transport. PMID:21164023

  15. Coexpression with Auxiliary ? Subunits Modulates the Action of Tefluthrin on Rat Na(v)1.6 and Na(v)1.3 Sodium Channels.

    PubMed

    Tan, Jianguo; Choi, Jin Sung; Soderlund, David M

    2011-11-01

    We expressed the rat Na(v)1.3 and Na(v)1.6 sodium channel ? subunit isoforms in Xenopus oocytes either alone or with the rat ?1 and ?2 auxiliary subunits in various combinations and assessed the sensitivity of the expressed channels to resting and use-dependent modification by the pyrethroid insecticide tefluthrin using the two-electrode voltage clamp technique. Coexpression with the ?1 and ?2 subunits, either individually or in combination, did not affecting the resting sensitivity of Na(v)1.6 channels to tefluthrin. Modification by tefluthrin of Na(v)1.6 channels in the absence of ? subunits was not altered by the application of trains of high-frequency depolarizing prepulses. By contrast, coexpression of the Na(v)1.6 channel with the ?1 subunit enhanced the extent of channel modification twofold following repeated depolarization. Coexpression of Na(v)1.6 with the ?2 subunit also slightly enhanced modification following repeated depolarization, but coexpression of Na(v)1.6 with both ? subunits caused enhanced modification following repeated depolarization that was indistinguishable from that found with Na(v)1.6+?1 channels. In contrast to Na(v)1.6, the resting modification by tefluthrin of Na(v)1.3 channels expressed in the absence of ? subunits was reduced by repeated depolarization. However, tefluthrin modification of the Na(v)1.3 ? subunit expressed with both ? subunits was enhanced 1.7-fold by repeated depolarization, thereby confirming that ? subunit modulation of use-dependent effects was not confined to the Na(v)1.6 isoform. These results show that the actions of pyrethroids on mammalian sodium channels in the Xenopus oocyte expression system are determined in part by the interactions of the sodium channel ? subunit with the auxiliary ? subunits that are part of the heteromultimeric sodium channel complexes found in neurons and other excitable cells. PMID:22577241

  16. Diffusion and the dynamics of displacive phase transitions in cryolite (Na 3 AlF 6 ) and chiolite (Na 5 Al 3 F 14 ): Multinuclear NMR studies

    Microsoft Academic Search

    Dane R. Spearing; Jonathan F. Stebbins; Ian Farnan

    1994-01-01

    Cryolite is a mixed-cation perovskite (Na2(NaAl)F6) which undergoes a monoclinic to orthorhombic displacive phase transition at ~550° C. Chiolite (Na5Al3F14) is associated with cryolite in natural deposits, and consists of sheets of corner sharing [AlF6] octahedra interlayered with edge-sharing [NaF6] octahedra. Multi-nuclear NMR line shape and relaxation time (T1) studies were performed on cryolite and chiolite in order to gain

  17. Influence of Na Doping on Structural and Optical Properties of (Na,Mg):ZnO Thin Films Prepared by Sol-Gel Process

    Microsoft Academic Search

    CaiZhen Zhang; Yonggang Chen; Su Liu; YongShun Wang

    2011-01-01

    Na element was introduced into preparation of Zn0.8Mg0.2O thin films, and high quality c-axis Na\\/Mg co-doped zinc oxide (ZnO) films with a nominal composition of Zn0.8-xNaxMg0.2O were prepared on pyrex glass substrates by sol-gel spin-coating method. Effects of Na composition on structural and optical properties of the films were investigated. Experimental results show that both Na and Mg elements were

  18. Complex transition metal hydrides incorporating ionic hydrogen: thermal decomposition pathway of Na2Mg2FeH8 and Na2Mg2RuH8.

    PubMed

    Humphries, Terry D; Matsuo, Motoaki; Li, Guanqiao; Orimo, Shin-Ichi

    2015-03-28

    Complex transition metal hydrides have potential technological application as hydrogen storage materials, smart windows and sensors. Recent exploration of these materials has revealed that the incorporation of anionic hydrogen into these systems expands the potential number of viable complexes, while varying the countercation allows for optimisation of their thermodynamic stability. In this study, the optimised synthesis of Na2Mg2TH8 (T = Fe, Ru) has been achieved and their thermal decomposition properties studied by ex situ Powder X-ray Diffraction, Gas Chromatography and Pressure-Composition Isotherm measurements. The temperature and pathway of decomposition of these isostructural compounds differs considerably, with Na2Mg2FeH8 proceeding via NaMgH3 in a three-step process, while Na2Mg2RuH8 decomposes via Mg2RuH4 in a two-step process. The first desorption maxima of Na2Mg2FeH8 occurs at ca. 400 °C, while Na2Mg2RuH8 has its first maxima at 420 °C. The enthalpy and entropy of desorption for Na2Mg2TH8 (T = Fe, Ru) has been established by PCI measurements, with the ?Hdes for Na2Mg2FeH8 being 94.5 kJ mol(-1) H2 and 125 kJ mol(-1) H2 for Na2Mg2RuH8. PMID:25732233

  19. Investigation of influence of NaOH and NaCl activating solutions on bentonite stabilization in suspension fertilizers

    NASA Astrophysics Data System (ADS)

    Hoffmann, Krystyna; Hoffmann, Józef; Mik?a, Daniel; Huculak-Mä Czka, Marta; Skut, Jakub

    2010-05-01

    1. INTRODUCTION Regular plants growth and their metabolic activity are determined by the macro- (C, H, O, N, P, S, K, Ca, Mg) and micronutrients (Fe, Mn, Zn, Cu, B, Mo, Cl, Ni). The role of these elements is very important, the excess as well as the deficiency have the negative influence on their development [1]. In order to increase yields and quality of crops a mineral, organic and mineral-organic fertilizers are applied. In the last years suspension fertilizers have been of great significance, taking the agricultural benefits into consideration. Suspension fertilizers are products of a new generation on account of higher nutrients concentrations than in the majority of other fertilizers, what makes them more efficient. Suspension fertilizers differ from solid fertilizers in more regular distribution on field. Nutrients are more concentrated what is economically relevant on account of the facilitated transportation. Examinations indicated, that nutrients from suspension fertilizers are more available than from solid fertilizers. The high concentration of nutrients in fertilizer is obtained by introducing a substance which holds them regularly in the suspension. Bentonites are the substances used for stabilization of suspension fertilizers most often [2,3]. Bentonites belong to ore of clay minerals, primarily made from minerals of smectite group, montmorillonite especially [4]. Bentonite loams were formulated as a result of Aluminium Silicate-bearing Rocks weathering and subsequent sedimentation in the aqueous environment. Characteristic features of rocks of the smectite group are their ability to absorb water (swelling), to form thixotrophic suspensions which aren't undergoing sedimentation process for a long time; as well as susceptibility to absorb cations and organic substances [4,5]. Therefore investigations have been carried out in order to evaluate the possibility of application of diverse loamy raw materials as suspension stabilizers for fertilizer purposes. In this paper research aimed at activating Jaroszów bentonite were presented. 2. MATERIALS AND METHODS The studies on activating clay minerals were carried out using the exchange of Ca2+, K+, Mg2+ ions to Na+ ions. For activation process the NaOH and NaCl solutions of concentrations 0,1M and 2,0M respectively were applied. For the purposes mentioned above 5g of weighed portion of mineral were introduced into four 250 ml conical flasks, two of them were filled with 100 ml of 0,1M and 2.0 M NaOH solution. Two remaining flasks were filled with 100 ml of 0,1M and 2.0 M NaCl solution. The samples preparred acoording to this instructions were shaken for 1 and 8 hours, and subsequently subjected to a vacuum filtration in order to separete solid fraction from filtrate. Mineral which remaied on the filter was dried in temperature of 110oC for 2 hours. 1g of dried mineral was collected for further examinations, mixed with 100 ml of distilled water and poured into the 25 ml measuring cylinder. Then every day for 14 days a change of the volume of deposit, suspension and pure solution above the suspension have been measured. 3. RESULTS DISCUSSION "Jaroszów" bentonite, activated with Na+ ions using 0,1M NaOH solution constitutes the most beneficial agent stabilizing the solid phase in the aqueous environment. The time factor didn't have considerable influence on bentonite activation. Results were similar for 1h as well as 8h. The addition of NaOH sustained suspension on respectively high level, about 80% vol., after 14 measurement days.

  20. Evidence of sympathetic cooling of Na+ ions by a Na magneto-optical trap in a hybrid trap

    NASA Astrophysics Data System (ADS)

    Sivarajah, I.; Goodman, D. S.; Wells, J. E.; Narducci, F. A.; Smith, W. W.

    2012-12-01

    A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutral atoms. This system provides a general cooling method that can be applied to species that do not have optically accessible transitions and can also potentially cool internal degrees of freedom. The long-range polarization potentials (V?-?/r4) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling of trapped Na+ ions, which are closed shell and therefore do not have a laser-induced atomic transition from the ground state, by equal-mass cold Na atoms in a magneto-optical trap.

  1. Excitatory amino acid-stimulated uptake of /sup 22/Na+ in primary astrocyte cultures

    SciTech Connect

    Kimelberg, H.K.; Pang, S.; Treble, D.H.

    1989-04-01

    In this study we have found that L-glutamic acid, as well as being taken up by a Na+-dependent mechanism, will stimulate the uptake of 22Na+ by primary astrocyte cultures from rat brain in the presence of ouabain. By simultaneously measuring the uptake of 22Na+ and L-3H-glutamate a stoichiometry of 2-3 Na+ per glutamate was measured, implying electrogenic uptake. Increasing the medium K+ concentration to depolarize the cells inhibited L-3H-glutamate uptake, while calculations of the energetics of the observed L-3H-glutamate accumulation also supported an electrogenic mechanism of at least 2 Na+:1 glutamate. In contrast, kinetic analysis of the Na+ dependence of L-3H-glutamate uptake indicated a stoichiometry of Na+ to glutamate of 1:1, but further analysis showed that the stoichiometry cannot be resolved by purely kinetic studies. Studies with glutamate analogs, however, showed that kainic acid was a very effective stimulant of 22Na+ uptake, but 3H-kainic acid showed no Na+ -dependent uptake. Furthermore, while L-3H-glutamate uptake was very sensitive to lowered temperatures, glutamate-stimulated 22Na+ uptake was relatively insensitive. These results indicate that glutamate-stimulated uptake of 22Na+ in primary astrocytes cultures cannot be explained solely by cotransport of Na+ with glutamate, and they suggest that direct kainic acid-type receptor induced stimulation of Na+ uptake also occurs. Since both receptor and uptake effects involve transport of Na+, accurate measurements of the Na+ :glutamate stoichiometry for uptake can only be done using completely specific inhibitors of these 2 systems.

  2. The local structure of Ca-Na pyroxenes. I. XANES study at the Na K-edge

    NASA Astrophysics Data System (ADS)

    Mottana, Annibale; Murata, Takatoshi; Wu, Ziyu; Marcelli, Augusto; Paris, Eleonora

    X-ray absorption Na K-edge spectra have been recorded on synthetic endmember jadeite and on a series of natural Ca-Na pyroxenes compositionally straddling the Jd-Di join. The C2/c members of the series are systematically different from the P2/n members. Differences can be interpreted and explained by comparing the experimental spectra with theoretical spectra. These have been calculated by the multiple-scattering formalism from the atomic positional parameters determined by single-crystal X-ray diffraction structure refinement on the same samples. In the full multiple scattering region of the spectra (1075 to 1090 eV) C-pyroxenes exhibit three features which reflect the 6-2 configuration of the O back-scattering atoms around the Na absorber located at the center of the cluster (site M2 of the jadeite structure). P-pyroxenes show more complicated spectra in which at least four (possibly five) features can be recognized; they reflect the two types of configuration (6-2 and 4-2-2) of O around Na in the two independent M2 and M21 eight-fold coordinated sites of the omphacite structure. A weak, sometimes poorly resolved peak at 1079 eV is diagnostic and discriminates C- from P-pyroxenes. The Garnet Ridge C2/c impure jadeite exhibits a spectrum which is intermediate between those of jadeite and omphacite. The Hedin-Lundqvist potential proves best for these insulating materials and allows multiple-scattering calculations agreeing well with experiments.

  3. Na+\\/H+ Exchanger1 Inhibitors Reduce Neuronal Excitability and Alter Na+ Channel Inactivation Properties in Rat Primary Sensory Neurons

    Microsoft Academic Search

    Chang-Ning Liu; Chris J. Somps

    2008-01-01

    Inhibitors of the Na1\\/H1 exchanger isoform 1 (NHE-1) have been associated with peripheral neuropathy in rats and dogs. Recent studies suggest that NHE-1 plays an important role in mediating neuronal excitability. To investigate potential NHE-1-mediated mechanisms contributing to neuronal toxicity, we studied the effects of NHE-1 inhibitors on nerve and dorsal root ganglion (DRG) neurons isolated from the adult rat.

  4. Theoretical verification of the differences between excitation of Na 3p and Na 3d by H+ and H- impact

    NASA Astrophysics Data System (ADS)

    Theodosiou, Constantine E.

    1988-11-01

    In a recent paper Allen, Anderson, and Lin

    [Phys. Rev. A 37, 349 (1988)]
    reported significant differences (that varied with impact energy), in the excitation of the Na3p and 3d levels when the excitation was caused by H+ and H- impact. I report theoretical calculations, based on a distorted-wave-type approximation, that reproduce at least the relative cross sections for the two impact cases, and I analyze quantitatively the origin of the above differences.

  5. Integração na criação de frangos de corte na microrregião de Viçosa - MG: viabilidade econômica e análise de risco

    Microsoft Academic Search

    Adelson Martins Figueiredo; Pedro Antônio dos Santos; Roberto Santolin; Brício dos Santos Reis

    2006-01-01

    Resumo: Na microrregião de Viçosa - MG, a criação de frango de corte via contratos de integração com a PIF-PAF S\\/A Indústria e Comércio tor- nou-se fonte adicional de renda para as propriedades rurais de pequeno e médio porte. Assim, este trabalho visou verificar a viabilidade de contratos de integração nessa região; especificamente, pretendeu-se ela - borar e analisar um

  6. Spectrophotometric Investigation of U(VI) Chloride Complexation in the NaCl/NaClO{sub 4} System

    SciTech Connect

    Paviet-Hartmann, P.; Lin, M.R.; Runde, W.H.

    1998-11-30

    Post closure radioactive release scenarios from geologic salt formation, such as the WIPP (Waste Isolation Pilot Plant)(USA) include hydrologic transport of radionuclides through a chloride saturated aquifer. Consequently, the understanding of actinide solution chemistry in brines is essential for modeling requiring accurate knowledge of the interaction between AnO{sub 2}{sup 2+} and chloride ions. Complexation constants of two U(VI) chloride species, UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0}, have been intensively studied for about 40 years using different methods. However, large uncertainties reflect the general difficulty in determining accurate stability constants of weak complexes. In order to model the behavior of U(VI) in brines, we studied the formation of its chloride complexes by UV-Vis spectroscopy as a function of the NaCl concentration at 25 C. The experiments were performed at constant ionic strength by varying the concentration ratio of NaCl and NaClO{sub 4}. Deconvolution resulted in single component absorption spectra for UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0}. The apparent stability constants of UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0} are at different ionic strengths and the experimental data are used to parameterize using the SIT approach.

  7. Search for solid conductors of Na/+/ and K/+/ ions - Five new conductors

    NASA Technical Reports Server (NTRS)

    Singer, J.; Kautz, H.; Fielder, W.; Fordyce, J.

    1975-01-01

    Five new conductors of positive Na and K ions, for use as separators in high energy secondary batteries, have been discovered. They include: (1) the pyrochlores NaTaWO6 and NaTa2O5F; (2) the bcc form of NaSbO3; and (3) the niobates 2Na2O-3Nb2O5 and 2K2O-3Nb2O5, with the alkali ions probably in open layers of the completely determined structure. On the basis of approximately 40 structure types, generalizations have been made regarding the relation between structure and ionic transport.

  8. Palytoxin Acts on Na + ,K + ATPase but not Nongastric H + ,K + ATPase

    Microsoft Academic Search

    Saida Guennoun-Lehmann; James E. Fonseca; Jean-Daniel Horisberger; Robert F. Rakowski

    2007-01-01

    Palytoxin (PTX) opens a pathway for ions to pass through Na,K-ATPase. We investigate here whether PTX also acts on nongastric\\u000a H,K-ATPases. The following combinations of cRNA were expressed in Xenopus laevis oocytes: Bufo marinus bladder H,K-ATPase ?2- and Na,K-ATPase ?2-subunits; Bufo Na,K-ATPase ?1- and Na,K-ATPase ?2-subunits; and Bufo Na,K-ATPase ?2-subunit alone. The response to PTX was measured after blocking endogenous

  9. Threshold processes of sodium ion emission from NaAu surface alloy

    NASA Astrophysics Data System (ADS)

    Knat'ko, M. V.; Lapushkin, M. N.

    2015-04-01

    We have studied threshold processes of Na+ ion emission from a semiconductor Na x Au y film formed on the surface of a gold substrate. In contrast to the classical notions of threshold processes involved in the surface ionization of alkali metal ions from heated metal surfaces, the diffusion exchange of atomic species between the surface and volume of the Na x Au y film ensures stable emission of Na+ ions from the substrate in the region of threshold temperatures. A diffusion mechanism of self-regulation of the surface coverage of alkali metal in the Na x Au y film is proposed.

  10. Magnetic structures of NaLMnWO6 perovskites (L=La,Nd,Tb)

    Microsoft Academic Search

    Graham King; Andrew S. Wills; Patrick M. Woodward

    2009-01-01

    The magnetic structures of the perovskites NaLaMnWO6 , NaNdMnWO6 , and NaTbMnWO6 , with rocksalt ordering of the Mn\\/W ions and layered ordering of Na and the rare-earth ions, have been determined by neutron powder diffraction. The manganese moments in NaLaMnWO6 order below 10 K with a propagation vector of k14=((1)\\/(2),0,(1)\\/(2)) and a moment of 3.99muB per Mn2+ ion. The

  11. Potassium depletion increases luminal Na+/H+ exchange and basolateral Na+:CO3=:HCO3- cotransport in rat renal cortex.

    PubMed Central

    Soleimani, M; Bergman, J A; Hosford, M A; McKinney, T D

    1990-01-01

    Most HCO3- reabsorption in proximal tubules occurs via electroneutral Na+/H+ exchange in brush border membranes (BBMS) and electrogenic Na+:CO3=:HCO3- cotransport in basolateral membranes (BLMS). Since potassium depletion (KD) increases HCO3- reabsorption in proximal tubules, we evaluated these transport systems using BBM and BLM vesicles, respectively, from control (C) and KD rats. Feeding rats a potassium deficient diet for 3-4 wk resulted in lower plasma [K+] (2.94 mEq/liter, KD vs. 4.47 C), and higher arterial pH (7.51 KD vs. 7.39 C). KD rats gained less weight than C but had higher renal cortical weight. Influx of 1 mM 22Na+ at 5 s (pHo 7.5, pHi 6.0, 10% CO2, 90% N2) into BLM vesicles was 44% higher in the KD group compared to C with no difference in equilibrium uptake. The increment in Na+ influx in the KD group was DIDS sensitive, suggesting that Na+:CO3=:HCO3- cotransport accounted for the observed differences. Kinetic analysis of Na+ influx showed a Km of 8.2 mM in KD vs. 7.6 mM in C and Vmax of 278 nmol/min/mg protein in KD vs. 177 nmol/min/mg protein in C. Influx of 1 mM 22Na+ at 5 s (pHo 7.5, pHi 6.0) into BBM vesicles was 34% higher in the KD group compared to C with no difference in equilibrium uptake. The increment in Na+ influx in the KD group was amiloride sensitive, suggesting that Na+/H+ exchange was responsible for the observed differences. Kinetic analysis of Na+ influx showed a Km of 6.2 mM in KD vs. 7.1 mM in C and Vmax of 209 nmol/min/mg protein in KD vs. 144 nmol/min/mg protein in C. Uptakes of Na(+)-dependent [3H]glucose into BBM and [14C]succinate into BLM vesicles were not different in KD and C groups, suggesting that the Na+/H+ exchanger and Na+:CO3=:HCO3- cotransporter activities were specifically altered in KD. We conclude that adaptive increases in basolateral Na+:CO3=:HCO3- cotransport and luminal Na+H+ exchange are likely responsible for increased HCO3- reabsorption in proximal tubules of KD animals. Images PMID:2170445

  12. Synthesis of Na2Mg3X2 (X = Sn, Pb) and Na4Mg4Sn3 and their crystal structures and thermoelectric properties

    NASA Astrophysics Data System (ADS)

    Yamada, Takahiro; Ishiyama, Ryo; Yamane, Hisanori

    2015-07-01

    Novel ternary stannides and a plumbide, Na2Mg3X2 (X = Sn, Pb) and Na4Mg4Sn3, were synthesized by heating the corresponding elements. The crystal structures were determined by single-crystal X-ray diffraction analysis, and the electrical conductivities and Seebeck coefficients were measured. The crystal structures of Na2Mg3X2 [orthorhombic, a = 7.3066(9) Å, b = 14.4559(13) Å, c = 6.6433(7) Å for X = Sn, a = 7.4272(11), b = 14.770(3), c = 6.6852(11) Å for X = Pb] are based on the Mg5Ga2-type structure (space group Ibam, Z = 4). Na4Mg4Sn3 crystallizes in an orthorhombic cell [a = 6.879(3) Å, b = 7.154(2) Å, c = 22.285(7) Å, space group Fmmm, Z = 4] with layers of disordered Na atom arrangement with defects. The electrical conductivities measured for the polycrystalline sintered samples of Na2Mg3Sn2, Na4Mg4Sn3, and Na2Mg3Pb2 were 1.9 × 105 S m?1 at 300 K, 1.6 × 105 S m?1 at 307 K and 3.3 × 105 S m?1 at 300 K, respectively. The Seebeck coefficients (S) of Na2Mg3Sn2, Na4Mg4Sn3, and Na2Mg3Pb2 were +47 to +72, +29 to +67, and +10 to +24 µV K?1, respectively, and increased with increasing temperature of 300–600 K.

  13. Thyroid hormone stimulates the Na(+)-PO4 symporter but not the Na(+)-SO4 symporter in renal brush border.

    PubMed

    Beers, K W; Dousa, T P

    1993-08-01

    In our previous studies we established that thyroid hormones [L-thyroxine (T4) or 3,5,3'-triiodothyronine (T3)] elicit an increase in Na(+)-Pi symport in rat and mouse renal brush-border membrane (BBM) vesicles (BBMV), but the Na(+)-coupled symports of other solutes were not influenced. However, a recent report [H. S. Tenenhouse, J. Lee, and N. Harvey. Am. J. Physiol. 261 (Renal Fluid Electrolyte Physiol. 30): F420-F426, 1991]claimed that T3 increases to a similar degree both Na(+)-Pi symport and Na(+)-SO4 symport in murine renal BBM. Adult male rats were fed either normal (0.7% Pi; NPD) or high-phosphate (1.4% Pi; HPD) diet and received T3 (0.2 mg/100 g body wt ip) for 3 days before the kidneys were removed, BBMV were prepared, and the transport rates were determined. Although the Na(+)-Pi symport significantly increased (delta = +35%) in both NPD and HPD rats treated with T3, the Na(+)-35SO4 symport and Na(+)-D-[3H]glucose symports were not influenced by T3. Furthermore, treatment of NPD-fed mice with T3 using a similar protocol as rats resulted in a significant increase (delta = +26%) of Na(+)-(Pi)4 symport, but did not alter Na(+)-SO4 symport or Na(+)-glucose symport. Our findings thus document that T3 regulates selectively the Na(+)-Pi symporter in BBM without having any effect on other major divalent anions, such as SO4. PMID:8368342

  14. Na(+) and Cl(-) ions show additive effects under NaCl stress on induction of oxidative stress and the responsive antioxidative defense in rice.

    PubMed

    Khare, Tushar; Kumar, Vinay; Kishor, P B Kavi

    2015-07-01

    Despite the fact that when subjected to salinity stress most plants accumulate high concentrations of sodium (Na(+)) and chloride (Cl(-)) ions in their tissues, major research has however been focused on the toxic effects of Na(+). Consequently, Cl(-) toxicity mechanisms in annual plants, particularly in inducing oxidative stress, are poorly understood. Here, the extent to which Na(+) and/or Cl(-) ions contribute in inducing oxidative stress and regulating the adaptive antioxidant defense is shown in two Indica rice genotypes differing in their salt tolerance. Equimolar (100 mM) concentrations of Na(+), Cl(-), and NaCl (EC???10 dS m(-1)) generated free-radical (O2 (•-), (•)OH) and non-radical (H2O2) forms of reactive oxygen species (ROS) and triggered cell death in leaves of 21-day-old hydroponically grown rice seedlings as evident by spectrophotometric quantifications and histochemical visualizations. The magnitude of ROS-mediated oxidative damage was higher in sensitive cultivar, whereas NaCl proved to be most toxic among the treatments. Salt treatments significantly increased activities of antioxidant enzymes and their isozymes including superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase. Na(+) and Cl(-) ions showed additive effects under NaCl in activating the antioxidant enzyme machinery, and responses were more pronounced in tolerant cultivar. The expression levels of SodCc2, CatA, and OsPRX1 genes were largely consistent with the activities of their corresponding enzymes. Salt treatments caused an imbalance in non-enzymatic antioxidants ascorbic acid, ?-tocopherol, and polyphenols, with greater impacts under NaCl than Na(+) and Cl(-) separately. Results revealed that though Cl(-) was relatively less toxic than its counter-cation, its effects cannot be totally ignored. Both the cultivars responded in the same manner, but the tolerant cultivar maintained lower Na(+)/K(+) and ROS levels coupled with better antioxidant defense under all three salt treatments. PMID:25547963

  15. Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO 5 glasses

    NASA Astrophysics Data System (ADS)

    Narita, K.; Takahashi, Y.; Benino, Y.; Fujiwara, T.; Komatsu, T.

    2004-05-01

    Crystalline phases and second-order optical nonlinearities in crystallized glasses of (Na,K)NbGeO 5 (i.e., xNa 2O · (25- x)K 2O · 25Nb 2O 5 · 50GeO 2) are examined. The molar volume of the glasses decreases with increasing Na 2O content, indicating that the glass structure of NaNbGeO 5 glass is more compact compared with KNbGeO 5 glass. The optical basicity of the glasses is 0.94-0.95, implying that chemical bonds among constituents ions are basically very ionic. (Na,K)NbGeO 5 glasses exhibit a unique crystallization depending on the Na 2O/K 2O ratio. The main crystalline phase in crystallized NaNbGeO 5 glass is the NaNbGeO 5 phase. KNbGeO 5 glass shows a prominent bulk nanocrystallization giving nanocrystals of the K 3.8Nb 5Ge 3O 20.4 phase. A glass with the composition of K 3.8Nb 5Ge 3O 20.4 also shows a bulk nanocrystallization. The crystallized glasses with K 3.8Nb 5Ge 3O 20.4 and NaNbGeO 5 crystalline phases do not show a second harmonic generation (SHG) at room temperature. The nonlinear optical (Na,K)NbO 3 phases showing a SHG are formed at the surface (˜5 ?m) of crystallized glasses with x=15 and 20, giving an orientation of the (1 1 0) plane. The present study suggests the presence of mixed-alkali effect in the crystallization behavior of (Na,K)NbGeO 5 glasses.

  16. Temperature-dependent solubility transition of Na?SO? in water and the effect of NaCl therein: solution structures and salt water dynamics.

    PubMed

    Bharmoria, Pankaj; Gehlot, Praveen Singh; Gupta, Hariom; Kumar, Arvind

    2014-11-01

    Dual, aqueous solubility behavior of Na2SO4 as a function of temperatures is still a natural enigma lying unresolved in the literature. The solubility of Na2SO4 increases up to 32.38 °C and decreases slightly thereafter at higher temperatures. We have thrown light on this phenomenon by analyzing the Na2SO4-water clusters (growth and stability) detected from temperature-dependent dynamic light scattering experiments, solution compressibility changes derived from the density and speed of sound measurements, and water structural changes/Na2SO4 (ion pair)-water interactions observed from the FT-IR and 2D DOSY (1)H NMR spectroscopic investigations. It has been observed that Na2SO4-water clusters grow with an increase in Na2SO4 concentration (until the solubility transition temperature) and then start decreasing afterward. An unusual decrease in cluster size and solution compressibility has been observed with the rise in temperature for the Na2SO4 saturated solutions below the solubility transition temperature, whereas an inverse pattern is followed thereafter. DOSY experiments have indicated different types of water cluster species in saturated solutions at different temperatures with varying self-diffusion coefficients. The effect of NaCl (5-15 wt %) on the solubility behavior of Na2SO4 at different temperatures has also been examined. The studies are important from both fundamental and industrial application points of view, for example, toward the clean separation of NaCl and Na2SO4 from the effluent streams of textile and tannery industries. PMID:25313635

  17. Extracellular Ca²+ alleviates NaCl-induced stomatal opening through a pathway involving H?O?-blocked Na+ influx in Vicia guard cells.

    PubMed

    Zhao, Xiang; Wang, Ya-Jing; Wang, Yan-Liang; Wang, Xi-Li; Zhang, Xiao

    2011-06-15

    To gain further insights into the function of extracellular Ca²+ in alleviating salt stress, Vicia faba guard cell protoplasts (GCPs) were patch-clamped in a whole-cell configuration. The results showed that 100 mM NaCl clearly induced Na+ influx across the plasma membrane in GCPs and promoted stomatal opening. Extracellular Ca²+ at 10 mM efficiently blocked Na+ influx and inhibited stomatal opening, which was partially abolished by La³+ (an inhibitor of plasma membrane Ca²+ channel) or catalase (CAT, a H?O? scavenger), respectively. These results suggest that the plasma membrane Ca²+ channels and H?O? possibly mediate extracellular Ca²+-blocked Na+ influx in GCPs. Furthermore, extracellular Ca²+ activated the plasma membrane Ca²+ channels under NaCl stress, which was partially abolished by CAT. These results, taken together, indicate that hydrogen peroxide (H?O?) likely regulates Na+ uptake by activating plasma membrane Ca²+ channels in GCPs. In accordance with this hypothesis, H?O? could mimic extracellular Ca²+ to activate Ca²+ channels and block Na+ influx in guard cells. A single-cell analysis of cytosolic free Ca²+ ([Ca²+](cyt)) using Fluo 3-AM revealed that extracellular Ca²+ induced the accumulation of cytosolic Ca²+ under NaCl stress, but had few effects on the accumulation of cytosolic Ca²+ under non-NaCl conditions. All of these results, together with our previous studies showing that extracellular Ca²+ induced the generation of H?O? in GCPs during NaCl stress, indicate that extracellular Ca²+ alleviates salt stress, likely by activating the H?O?-dependent plasma membrane Ca²+ channels, and the increase in cytosolic Ca²+ appears to block Na+ influx across the plasma membrane in Vicia guard cells, leading to stomatal closure and reduction of water loss. PMID:21367483

  18. Internalization of proximal tubular type II Na-P(i) cotransporter by PTH: immunogold electron microscopy.

    PubMed

    Traebert, M; Roth, J; Biber, J; Murer, H; Kaissling, B

    2000-01-01

    Physiological/pathophysiological alterations in proximal tubular P(i) reabsorption are associated with an altered brush-border membrane (BBM) expression of type II Na-P(i) cotransporter molecules. Reduction is achieved by an internalization and lysosomal degradation and an increase in P(i) reabsorption by new synthesis and BBM insertion of type II Na-P(i) cotransporters. In the present study, we investigated by immunohistochemistry and immunogold electron microscopy the routing of internalized rat type II Na-P(i) cotransporters (NaPi-2). In kidney of rats on a chronic low-P(i) diet, NaPi-2 is mainly localized in the BBM, in cisterns of the Golgi apparatus and sparsely also in large endocytotic vacuoles and lysosomes. Fifteen minutes after the injection of the 1-34 analog of parathyroid hormone (PTH), the amount of NaPi-2 was decreased in the BBM and increased in endocytotic vesicles. NaPi-2 molecules colocalized with horseradish peroxidase injected prior to the injection of PTH. Vesicles labeled for NaPi-2 were occasionally also labeled for clathrin or the adaptor protein AP2. We conclude that NaPi-2 molecules enter the subapical compartment from where NaPi-2-containing vesicles are segregated off and directed to the lysosomes. A clathrin-mediated pathway may contribute to the PTH-induced internalization of NaPi-2. PMID:10644666

  19. Glial Nax channels control lactate signaling to neurons for brain [Na+] sensing.

    PubMed

    Shimizu, Hidetada; Watanabe, Eiji; Hiyama, Takeshi Y; Nagakura, Ayano; Fujikawa, Akihiro; Okado, Haruo; Yanagawa, Yuchio; Obata, Kunihiko; Noda, Masaharu

    2007-04-01

    Sodium (Na) homeostasis is crucial for life, and Na levels in body fluids are constantly monitored in the brain. The subfornical organ (SFO) is the center of the sensing responsible for the control of salt-intake behavior, where Na(x) channels are expressed in specific glial cells as the Na-level sensor. Here, we show direct interaction between Na(x) channels and alpha subunits of Na(+)/K(+)-ATPase, which brings about Na-dependent activation of the metabolic state of the glial cells. The metabolic enhancement leading to extensive lactate production was observed in the SFO of wild-type mice, but not of the Na(x)-knockout mice. Furthermore, lactate, as well as Na, stimulated the activity of GABAergic neurons in the SFO. These results suggest that the information on a physiological increase of the Na level in body fluids sensed by Na(x) in glial cells is transmitted to neurons by lactate as a mediator to regulate neural activities of the SFO. PMID:17408578

  20. Composite PEOn:NaTFSI polymer electrolyte: Preparation, thermal and electrochemical characterization

    NASA Astrophysics Data System (ADS)

    Serra Moreno, J.; Armand, M.; Berman, M. B.; Greenbaum, S. G.; Scrosati, B.; Panero, S.

    2014-02-01

    Membranes of sodium bis(trifluoromethanesulfonate) imide (NaTFSI) complexed with poly(ethylene oxide) (PEO) salt have been prepared by a solvent-free hot-pressing technique with different EO:Na molar ratio. All membranes show good ionic conductivities in the range of 10-3 S cm-1 above 70 °C. However, the more NaTFSI-concentrated samples are sticky gums due to the plasticizing nature of the anion. The PEO20:NaTFSI sample exhibits the compromise of conductivity, thermal and mechanical properties. The addition of nanometric SiO2 to the PEO20:NaTFSI membranes further enhances their mechanical properties. Moreover, the PEO20:NaTFSI + 5 wt.% SiO2 membranes show similar ionic conductivity and similar anodic electrochemical stability in comparison to the ceramic free PEO20:NaTFSI sample. In a Na(s)/polymer electrolyte/Na(s) symmetrical cell followed up to 30 days, the presence of the ceramic filler slightly increased the interface resistance in comparison to the ceramic-free membrane. Nuclear magnetic resonance determinations of anion diffusion coefficients and Na+ mobility suggest that presence of filler may have a positive affect on the cation transference number that is in accordance with the tNa+ transference number measurement.

  1. Hydrophilic C terminus of Salicornia europaea vacuolar Na(+)/H(+) antiporter is necessary for its function.

    PubMed

    Wu, Guangxia; Wang, Gang; Ji, Jing; Tian, Xiaowei; Gao, Hailing; Zhao, Qing; Li, Jing; Wang, Yurong

    2014-08-01

    Plant vacuolar Na(+)/H(+) antiporters play important roles in cellular ion homeostasis,vacuolar pH regulation and sequestration of Na(+) ions into the vacuole. Previous research showed that hydrophilic C-terminal region of Arabidopsis AtNHX1 negatively regulates the Na(+)/H(+) transporting activity. In this study, we truncated the hydrophilic C terminus of a vacuolar Na(+) /H(+) antiporter gene from Salicornia europaea (SeNHX1) to generate its derivative, SeNHX1-?C. Expression of SeNHX1 and SeNHX1-?C in yeast mutant showed that SeNHX1 significantly improved the tolerance to NaCl; however, the expression of SeNHX1-?C enormously decreased the tolerance to NaCl. Overall, these results suggest that the hydrophilic C-terminal region of SeNHX1 is required for Na(+)/H(+) exchanging activity of SeNHX1. PMID:25189237

  2. Salt and gene expression: evidence for [Na+]i/[K+]i-mediated signaling pathways.

    PubMed

    Orlov, Sergei N; Hamet, Pavel

    2015-03-01

    Our review focuses on the recent data showing that gene transcription and translation are under the control of signaling pathways triggered by modulation of the intracellular sodium/potassium ratio ([Na+]i/[K+]i). Side-by-side with sensing of osmolality elevation by tonicity enhancer-binding protein (TonEBP, NFAT5), [Na+]i/[K+]i-mediated excitation-transcription coupling may contribute to the transcriptomic changes evoked by high salt consumption. This novel mechanism includes the sensing of heightened Na+ concentration in the plasma, interstitial, and cerebrospinal fluids via augmented Na+ influx in the endothelium, immune system cells, and the subfornical organ, respectively. In these cells, [Na+]i/[K+]i ratio elevation, triggered by augmented Na+ influx, is further potentiated by increased production of endogenous Na+,K+-ATPase inhibitors documented in salt-sensitive hypertension. PMID:25479826

  3. Study of OSL in NaCl:Cu co-doped with Ca and Ca,P

    NASA Astrophysics Data System (ADS)

    More, Y. K.; Wankhede, S. P.; Moharil, S. V.

    2013-06-01

    New results on photo, thermo and optically stimulated luminescence in NaCl:Cu, NaCl:Ca,Cu and NaCl:Ca,Cu,P are reported. Strong PL, TL is observed in NaCl:C? Initial OSL counts of NaCl:Ca,Cu is approximately 2 times more than that in standard phosphor LMP. The rate of OSL depletion for standard phosphor LMP is only 2.5 times less as compared to that of the NaCl:Cu, NaCl:Ca,Cu. NaCl host thus deserves much more attention than it has received up till now. NaCl:Cu, NaCl:Ca,Cu, NaCl:Ca,Cu,P may be useful as dosimetric materials in online radiation Dosimetry.

  4. Different mechanisms of adaptive increase in Na+-Pi cotransport across renal brush-border membrane.

    PubMed

    Yusufi, A N; Szczepanska-Konkel, M; Hoppe, A; Dousa, T P

    1989-05-01

    We explored the biochemical mechanism by which thyroid hormone (T3) and low-phosphate diet (LPD) cause an adaptive increase in Na+-Pi cotransport across renal brush-border membrane (BBM). The rate of Na+-Pi cotransport was determined by 32Pi uptake by BBM vesicles (BBMV), and the number of Na+-Pi symporters was assessed by binding of [14C]phosphonoformic acid (PFA) on BBMV. In BBMV of both T3-treated rats and LPD-fed rats, the Na+ gradient-dependent 32Pi uptake increased (Vmax increased; Km Pi was not changed). The Na+-dependent [14C]PFA binding on BBMV increased (higher Vmax, no change in Km PFA) in response to T3, but it remained unchanged in rats fed LPD. Both the increase of Na+-Pi cotransport and of Na+-dependent [14C]PFA binding in response to T3 were blocked by actinomycin D or cycloheximide. Addition of benzyl alcohol to BBMV in vitro increased Na+-Pi cotransport, but [14C]PFA binding did not change; the [3H]phlorizin binding and cotransports of other solutes decreased or did not change. The exposure of BBMV to cholesterol decreased Na+-Pi cotransport without changing [14C]PFA binding. We suggest that the adaptive increase of Na+-Pi cotransport elicited by T3 is due to an increase in number of Na+-Pi cotransporters in BBM. In contrast, in response to LPD the number of Na+-Pi cotransporters is unchanged, and the increased Na+-Pi cotransport is due to faster translocation of Na+ with Pi due to enhanced fluidity of BBM. PMID:2524168

  5. Polarized Na+/H+ exchange function is pliable in response to transepithelial gradients of propionate.

    PubMed Central

    Rowe, W A; Lesho, M J; Montrose, M H

    1994-01-01

    Short-chain fatty acids are produced at high concentration in the colonic lumen and stimulate electroneutral Na+ absorption by activating apical Na+/H+ exchange in colonocytes. We used an epithelial cell line derived from a human colon carcinoma (HT29-18-C1) to study activation of apical and basolateral Na+/H+ exchange by a short-chain fatty acid, propionate. Confluent cell monolayers on membrane filters were loaded with 2',7'-bis(2-carboxyethyl)-5 (and 6)-carboxyfluorescein (a fluorescent pH indicator) and intracellular pH was monitored with a digital fluorescence imaging microscope. Cells acidified by transient exposure to NH4Cl demonstrated both apical and basolateral Na+/H+ exchange. In this condition, apical Na+/H+ exchange was 50% of the total Na+/H+ exchange activity. Similar results were obtained when cells were bilaterally perfused with apical and basolateral propionate in an isosmotic medium (130 mM propionate at each membrane surface). However, apical Na+/H+ exchange was a significantly larger fraction (76%) of the total Na+/H+ exchange activity when cells were acidified by exposure to apical propionate alone. Conversely, in cells acidified by basolateral propionate alone, apical Na+/H+ exchange was 21% of the total Na+/H+ exchange activity. The change in relative activity was observed in individual cells which expressed both apical and basolateral Na+/H+ exchange and occurred rapidly (within 7 min). In the presence of transepithelial propionate gradients, all Na(+)-dependent alkalinization was sensitive to 3 microM 5-(N-ethyl-N-isopropyl)amiloride, a potent Na+/H+ exchange inhibitor. These results suggest that transepithelial gradients of short-chain fatty acids, which occur in vivo, can cause preferential activation of apical Na+/H+ exchange. PMID:8016132

  6. Quantification of Na+,K+ pumps and their transport rate in skeletal muscle: Functional significance

    PubMed Central

    2013-01-01

    During excitation, muscle cells gain Na+ and lose K+, leading to a rise in extracellular K+ ([K+]o), depolarization, and loss of excitability. Recent studies support the idea that these events are important causes of muscle fatigue and that full use of the Na+,K+-ATPase (also known as the Na+,K+ pump) is often essential for adequate clearance of extracellular K+. As a result of their electrogenic action, Na+,K+ pumps also help reverse depolarization arising during excitation, hyperkalemia, and anoxia, or from cell damage resulting from exercise, rhabdomyolysis, or muscle diseases. The ability to evaluate Na+,K+-pump function and the capacity of the Na+,K+ pumps to fill these needs require quantification of the total content of Na+,K+ pumps in skeletal muscle. Inhibition of Na+,K+-pump activity, or a decrease in their content, reduces muscle contractility. Conversely, stimulation of the Na+,K+-pump transport rate or increasing the content of Na+,K+ pumps enhances muscle excitability and contractility. Measurements of [3H]ouabain binding to skeletal muscle in vivo or in vitro have enabled the reproducible quantification of the total content of Na+,K+ pumps in molar units in various animal species, and in both healthy people and individuals with various diseases. In contrast, measurements of 3-O-methylfluorescein phosphatase activity associated with the Na+,K+-ATPase may show inconsistent results. Measurements of Na+ and K+ fluxes in intact isolated muscles show that, after Na+ loading or intense excitation, all the Na+,K+ pumps are functional, allowing calculation of the maximum Na+,K+-pumping capacity, expressed in molar units/g muscle/min. The activity and content of Na+,K+ pumps are regulated by exercise, inactivity, K+ deficiency, fasting, age, and several hormones and pharmaceuticals. Studies on the ?-subunit isoforms of the Na+,K+-ATPase have detected a relative increase in their number in response to exercise and the glucocorticoid dexamethasone but have not involved their quantification in molar units. Determination of ATPase activity in homogenates and plasma membranes obtained from muscle has shown ouabain-suppressible stimulatory effects of Na+ and K+. PMID:24081980

  7. Phase diagram of the LiNO3-NaNO3-NaCl-Sr(NO3)2 salt system

    NASA Astrophysics Data System (ADS)

    Rasulov, A. I.; Gasanaliev, A. M.; Mamedova, A. K.; Gamataeva, B. Yu.

    2015-04-01

    The phase diagram of the quaternary LiNO3-NaNO3-NaCl-Sr(NO3)2 system is studied by means of differential thermal analysis, and the compositions and crystallization temperatures of nonvariant equilibrium phases are revealed. The temperature dependence of conductivity in eutectic and peritectic salt compositions is investigated.

  8. NaOH-rich corner of the (Na/sup +/, Ca/sup 2 +/) (OH/sup -/, CO/sub 3//sup 2 -/) reciprocal system. [LMFBR

    SciTech Connect

    Sallach, R.A.

    1983-08-01

    The sodium-rich portion of the binary system (NaOH)/sub 2/ - Ca(OH)/sub 2/ and the reciprocal system (Na/sup +/, Ca/sup 2 +/) (OH/sup -/, CO/sub 3//sup 2 -/) are described. The (NaOH)/sub 2/ - Ca(OH)/sub 2/ system has a peritectic decomposition at 330 +- 5/sup 0/C and a mole fraction Ca(OH)/sub 2/ of 0.0055 +- 0.0020. A compound with the apparent stoichiometry Na/sub 6/Ca(OH)/sub 8/ is formed in the system. The compound melts at 560 +- 10/sup 0/C. X-ray diffraction data for this compound are presented. Solid state solubility of the compound in ..beta..-NaOH causes a depression in the temperature of the ..cap alpha.. ..-->.. ..beta.. phase change. Liquidus data for 27 compositions in the NaOH-rich portion of the reciprocal system are reported. These data may be interpreted in terms of a ternary peritectic or a semi-eutectic. Ternary invariant temperatures were not measured. An apparent invariant at 285 +- 5/sup 0/C is attributed to a disequilibrium eutectic reaction between NaOH and Na/sub 2/CO/sub 3/.

  9. NaBrO3\\/NaHSO4 · H2O as a Versatile Reagent System for the Oxidation of Benzylic Alcohols and Aldehydes

    Microsoft Academic Search

    Farhad Shirini; Mohammad Ali Zolfigol; Shayesteh Torabi

    2006-01-01

    The oxidation of benzylic alcohols and aldehydes by NaBrO3 is efficiently promoted in the presence of NaHSO4 · H2O. All reactions were performed under mild and completely heterogeneous conditions in good to high yields.

  10. Oxidation of dermatan sulfate with a NaOCl-NaBr-2,2,6,6-tetramethylpiperidine-1-oxyl reagent in an aqueous medium

    Microsoft Academic Search

    I. Yu. Ponedel’kina; E. A. Khaibrahmanova; V. N. Odinokov; L. M. Khalilov; U. M. Dzhemilev

    2010-01-01

    The oxidation of primary hydroxyl groups in dermatan sulfate with the NaOCl-NaBr-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)\\u000a reagent in an aqueous alkaline medium was carried out for the first time. Modified dermatan sulfates containing hydrated aldehyde\\u000a (15–50%) and carboxyl (25–100%) groups were obtained.

  11. In situ synthesis of Na2Ti7O15 nanotubes on a Ti net substrate as a high performance anode for Na-ion batteries.

    PubMed

    Li, Huan; Fei, Hailong; Liu, Xin; Yang, Jie; Wei, Mingdeng

    2015-05-21

    Na2Ti7O15 nanotubes on a Ti net substrate were fabricated for the first time and used directly as a binder-free anode for Na-ion batteries. This material exhibited high reversible capacity and excellent stability which might be due to its unique characteristics including the porous substrate, nanoscale large surface area, nanotube structure and so on. PMID:25958953

  12. Kinetic diversity of Na+ channel bursts in frog skeletal muscle

    PubMed Central

    1989-01-01

    Individual Na+ channels of dissociated frog skeletal muscle cells at 10 degrees C fail to inactivate in 0.02% of depolarizing pulses, thus producing bursts of openings lasting hundreds of milliseconds. We present here a kinetic analysis of 87 such bursts that were recorded in multi-channel patches at four pulse potentials. We used standard dwell- time histograms as well as fluctuation analysis to analyze the gating kinetics of the bursting channels. Since each burst contained only 75- 150 openings, detailed characterization of the kinetics from single bursts was not possible. Nevertheless, at this low kinetic resolution, the open and closed times could be well fitted by single exponentials (or Lorentzians for the power spectra). The best estimates of both the open and closed time constants produced by either technique were much more broadly dispersed then expected from experimental or analytical variability, with values varying by as much as an order of magnitude. Furthermore, the values of the open and closed time constants were not significantly correlated with one another from burst to burst. The bursts thus expressed diverse kinetic behaviors, all of which appear to be manifestations of a single type of Na+ channel. Although the opening and closing rates were dispersed, their average values were close to those of alpha m and 2 beta m derived from fits to the early transient Na+ currents over the same voltage range. We propose a model in which the channel has both primary states (e.g., open, closed, and inactivated), as well as "modes" that are associated with independent alterations in the rate constants for transition between each of these primary states. PMID:2551999

  13. NaV3O8 nanosheet@polypyrrole core-shell composites with good electrochemical performance as cathodes for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Kang, Hongyan; Liu, Yongchang; Shang, Minghui; Lu, Tianyu; Wang, Yijing; Jiao, Lifang

    2015-05-01

    Novel NaV3O8 nanosheet@polypyrrole core-shell composites have been successfully prepared for the first time via a chemical oxidative polymerization method. Based on the morphological and microstructural characterization, it was found that polypyrrole (PPy) was uniformly wrapped on the surfaces of the NaV3O8 nanosheets. When used as a cathode for Na-ion batteries, the as-synthesized NaV3O8@10% PPy composite showed significantly improved cycling performance (with a discharge capacity of 99 mA h g-1 after 60 cycles at 80 mA g-1) and better rate capacity (with a discharge capacity of 63 mA h g-1 at a high current density of 640 mA g-1) than pristine NaV3O8 nanosheets. The greatly enhanced performance benefits from the unique core-shell structure, where the PPy coating not only prevents the pulverization and aggregation of the lamellar NaV3O8 nanosheets during cycling, which can improve the cycling stability, but also enhances the electrical conductivity of the composite, which can facilitate Na+ ion diffusion.Novel NaV3O8 nanosheet@polypyrrole core-shell composites have been successfully prepared for the first time via a chemical oxidative polymerization method. Based on the morphological and microstructural characterization, it was found that polypyrrole (PPy) was uniformly wrapped on the surfaces of the NaV3O8 nanosheets. When used as a cathode for Na-ion batteries, the as-synthesized NaV3O8@10% PPy composite showed significantly improved cycling performance (with a discharge capacity of 99 mA h g-1 after 60 cycles at 80 mA g-1) and better rate capacity (with a discharge capacity of 63 mA h g-1 at a high current density of 640 mA g-1) than pristine NaV3O8 nanosheets. The greatly enhanced performance benefits from the unique core-shell structure, where the PPy coating not only prevents the pulverization and aggregation of the lamellar NaV3O8 nanosheets during cycling, which can improve the cycling stability, but also enhances the electrical conductivity of the composite, which can facilitate Na+ ion diffusion. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02064f

  14. Branching ratios for the beta decay of Na-21 

    E-print Network

    Iacob, V. E.; Hardy, John C.; Gagliardi, Carl A.; Goodwin, J.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Tribble, Robert E.; Zhai, Y.; Towner, I. S.

    2006-01-01

    LN2-cooled hydrogen gas target. The ejectiles from the reaction were fully stripped and, after passing through the MARS spectrometer [7], produced a 21Na secondary beam of >99% purity at the extraction slits in the MARS focal plane. This beam... was positioned between a 1-mm-thick BC404 scintillator to detect ?+ particles, and a 70%HPGe detector for ? rays. Two timing modes were used: in one, the collection and detection periods were 3 and 30 s, respectively; in the other, they were 6 and 60 s...

  15. Interaction effects of a topological Dirac semimetal Na3Bi

    NASA Astrophysics Data System (ADS)

    Zhang, Ruixing; Hutasoit, Jimmy; Liu, Chaoxing

    2015-03-01

    We study the interaction effects of a topological Dirac semimetal Na3Bi based on the mean field theory. The phase diagram can be classified by two kinds of chiral-symmetry-breaking order parameters: nematic orders that break rotational symmetry and charge-density-wave (CDW) order that break translational symmetry. Under strong magnetic field, gapless Landau levels will be formed and result in instabilities due to the above order parameters. These order parameters are generally complex, and are identified as complex mass terms, which introduce axions into the low energy theory. The possible experimental consequence is also studied.

  16. Strangeness measurements in NA49 experiment with Pb projectiles

    Microsoft Academic Search

    S. Margetis S. Margetis; H. Appelshäuser; J. Bächler; S. J. Bailey; D. Barna; L. S. Barnby; J. Bartke; R. A. Barton; H. Bialkowska; A. Billmeier; C. O. Blyth; R. Bock; C. Bormann; F. P. Brady; R. Brockmann; R. Brun; P. Buncic; H. L. Caines; L. D. Carr; D. Cebra; G. E. Cooper; J. G. Cramer; M. Cristinziani; P. Csato; J. Dunn; V. Eckardt; F. Eckhardt; M. I. Ferguson; H. G. Fischer; D. Flierl; Z. Fodor; P. Foka; V. Friese; M. Fuchs; F. Gabler; J. Gal; M. Gazdzicki; E. Gladysz; J. Grebieszkow; J. Günther; J. W. Harris; S. Hegyi; T. Henkel; L. A. Hill; H. Hümmler; D. Irmscher; P. Jacobs; P. G. Jones; K. Kadija; V. I. Kolesnikov; M. Kowalski; B. Lasiuk; P. Lévai; A. I. Malakhov; C. Markert; G. L. Melkumov; A. Mock; J. Molnár; J. M. Nelson; M. Oldenburg; G. Odyniec; G. Palla; A. D. Panagiotou; A. Petridis; A. Piper; R. J. Porter; A. M. Poskanzer; D. J. Prindle; F. Pühlhofer; W. Rauch; J. G. Reid; R. Renfordt; W. Retyk; H. G. Ritter; D. Röhrich; C. Roland; G. Roland; H. Rudolph; A. Rybicki; A. Sandoval; H. Sann; A. Yu Semenov; E. Schäfer; D. Schmischke; N. Schmitz; S. Schönfelder; P. Seyboth; J. Seyerlein; F. Sikler; E. Skrzypczak; R. Snellings; G. T. A. Squier; R. Stock; H. Ströbele; Chr Struck; I. Szentpetery; J. Sziklai; T. A. Trainor; S. Trentalange; T. Ullrich; M. Vassiliou; G. Veres; G. Vesztergombi; D. Vranic; F. Wang; D. D. Weerasundara; S. Wenig; C. Whitten; T. Wienold; L. Wood; N. Xu; T. A. Yates; J. Zimanyi; R. Zybert

    1999-01-01

    Charged and neutral strange particle production was studied by the NA49 experiment at CERN. Preliminary inclusive spectra are presented for 0954-3899\\/25\\/2\\/006\\/img5, 0954-3899\\/25\\/2\\/006\\/img6, 0954-3899\\/25\\/2\\/006\\/img7, 0954-3899\\/25\\/2\\/006\\/img8, 0954-3899\\/25\\/2\\/006\\/img9 and 0954-3899\\/25\\/2\\/006\\/img10 particles, measured in a region close to mid-rapidity, for central Pb+Pb collisions at 158 GeV per nucleon. An enhanced strange particle production relative to properly scaled elementary nucleon-nucleon collisions is observed, but its

  17. An investigation of the solar NA D line observations

    NASA Astrophysics Data System (ADS)

    Tomley, L.

    1980-01-01

    A method is presented in which the Doppler width can be obtained directly from the intensity integral given observations of a single line at several values of the cosine of the angle of observation. The method is applied to the cores of the solar Na D-line observations of Waddell (1962) and the results are found to be inconsistent with the results of test cases on synthetic data. It is suggested that the observed profiles are affected differently by some factor, quite possibly the incomplete removal of terrestrial H2O contamination in D 2, and that this difference would have a serious effect on inversion methods employing intercomparison techniques.

  18. The CERES/NA45 Radial Drift Time Projection Chamber

    E-print Network

    The CERES Collaboration

    2008-03-26

    The design, calibration, and performance of the first radial drift Time Projection Chamber (TPC) are presented. The TPC was built and installed at the CERES/NA45 experiment at the CERN SPS in the late nineties, with the objective to improve the momentum resolution of the spectrometer. The upgraded experiment took data twice, in 1999 and in 2000. After a detailed study of residual distortions a spatial resolution of 340 um in the azimuthal and 640 um in the radial direction was achieved, corresponding to a momentum resolution of Dp/p = sqrt{(1% * p/GeV)^2 + (2%)^2}.

  19. Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi.

    PubMed

    Dong, Yongkwan; Chai, Ping; Beekman, Matt; Zeng, Xiaoyu; Tritt, Terry M; Nolas, George S

    2015-06-01

    Single crystals of the ternary clathrate-I Na8Al8Si38 were synthesized by kinetically controlled thermal decomposition (KCTD), and microcrystalline Na8Al8Si38 was synthesized by spark plasma sintering (SPS) using a NaSi + NaAlSi mixture as the precursor. Na8AlxSi46-x compositions with x ? 8 were also synthesized by SPS from precursor mixtures of different ratios. The crystal structure of Na8Al8Si38 was investigated using both Rietveld and single-crystal refinements. Temperature-dependent transport and UV/vis measurements were employed in the characterization of Na8Al8Si38, with diffuse-reflectance measurement indicating an indirect optical gap of 0.64 eV. Our results indicate that, when more than one precursor is used, both SPS and KCTD are effective methods for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques. PMID:25985168

  20. Impact of different Na-incorporating methods on Cu(In,Ga)Se2 thin film solar cells with a low-Na substrate.

    PubMed

    Ye, Shenglin; Tan, Xiaohui; Jiang, Minlin; Fan, Bin; Tang, Ken; Zhuang, Songlin

    2010-03-20

    As a kind of Na-incorporating control method, NaF co-evaporation or soda-lime glass thin films (SLGTFs) are useful to improve the photovoltaic performance of Cu(In,Ga)Se(2) (CIGS) cells fabricated on low-Na substrates. X-ray diffraction (XRD) patterns and scanning electron microscope pictures demonstrate that the grain size of CIGS thin film is reduced with the addition of Na. In addition, a variance of the preferred orientation is found by XRD patterns in terms of SLGTF samples. By a use of 100 nm thick SLGTF as a Na source, the best CIGS solar cell with an efficiency of 13.42% has been obtained. PMID:20300164

  1. A new diabatic representation of the coupled potential energy surfaces for Na(3p P-2) + H2 yields Na(3s S-2) + H2 or NaH + H

    NASA Technical Reports Server (NTRS)

    Halvick, Philippe; Truhlar, Donald G.

    1992-01-01

    A diabatic representation is presented of the coupled potential-energy surfaces for Na(3p P-2) + H2 yields Na (3s S-2) + H2 or NaH + H. The representation is designed to yield, upon diagonalization, realistic values for the two lowest energy adiabatic states at both asymptotes of the chemical reaction as well as near the conical intersection in the three-body interaction region. It is economical to evaluate and portable. It is suitable for dynamics calculations on both the quenching process and the electronically nonadiabatic chemical reaction.

  2. Cell Degradation of a Na-NiCl2 (ZEBRA) Battery

    SciTech Connect

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.

    2013-11-01

    In this work, the parameters influencing the degradation of a Na-NiCl2 (ZEBRA) battery were investigated. Planar Na-NiCl2 cells using ?”-alumina solid electrolyte (BASE) were tested with different C-rates, Ni/NaCl ratios, and capacity windows, in order to identify the key parameters for the degradation of Na-NiCl2 battery. The morphology of NaCl and Ni particles were extensively investigated after 60 cycles under various test conditions using a scanning electron microscope. A strong correlation between the particle size (NaCl and Ni) and battery degradation was observed in this work. Even though the growth of both Ni and NaCl can influence the cell degradation, our results indicate that the growth of NaCl is a dominant factor in cell degradation. The use of excess Ni seems to play a role in tolerating the negative effects of particle growth on degradation since the available active surface area of Ni particles can be still sufficient even after particle growth. For NaCl, a large cycling window was the most significant factor, of which effects were amplified with decrease in Ni/NaCl ratio.

  3. Multiple transport modes of the cardiac Na+/Ca2+ exchanger.

    PubMed

    Kang, Tong Mook; Hilgemann, Donald W

    2004-02-01

    The cardiac Na+/Ca2+ exchanger (NCX1; ref. 2) is a bi-directional Ca2+ transporter that contributes to the electrical activity of the heart. When, and if, Ca2+ is exported or imported depends on the Na+/Ca2+ exchange ratio. Whereas a ratio of 3:1 (Na+:Ca2+) has been indicated by Ca2+ flux equilibrium studies, a ratio closer to 4:1 has been indicated by exchange current reversal potentials. Here we show, using an ion-selective electrode technique to quantify ion fluxes in giant patches, that ion flux ratios are approximately 3.2 for maximal transport in either direction. With Na+ and Ca2+ on both sides of the membrane, net current and Ca2+ flux can reverse at different membrane potentials, and inward current can be generated in the absence of cytoplasmic Ca2+, but not Na+. We propose that NCX1 can transport not only 1 Ca2+ or 3 Na+ ions, but also 1 Ca2+ with 1 Na+ ion at a low rate. Therefore, in addition to the major 3:1 transport mode, import of 1 Na+ with 1 Ca2+ defines a Na+-conducting mode that exports 1 Ca2+, and an electroneutral Ca2+ influx mode that exports 3 Na+. The two minor transport modes can potentially determine resting free Ca2+ and background inward current in heart. PMID:14765196

  4. The lung amiloride-sensitive Na+ channel: biophysical properties, pharmacology, ontogenesis, and molecular cloning.

    PubMed Central

    Voilley, N; Lingueglia, E; Champigny, G; Mattéi, M G; Waldmann, R; Lazdunski, M; Barbry, P

    1994-01-01

    Water balance in the lung is controlled via active Na+ and Cl- transport. Electrophysiological measurements on lung epithelial cells demonstrated the presence of a Na+ channel that is inhibited by amiloride (K0.5 = 90 nM) and some of its derivatives such as phenamil (K0.5 = 19 nM) and benzamil (K0.5 = 14 nM) but not by ethylisopropylamiloride. An amiloride-sensitive Na+ channel of 4 pS was recorded from outside-out patches excised from the apical membrane. This channel is highly selective for Na+ (PNa+/PK+ > or = to 10). Isolation of a human lung cDNA led to the primary structure of the lung Na+ channel. The corresponding protein is 669 residues long and has two large hydrophobic domains. An amiloride-sensitive Na(+)-selective current apparently identical to the one observed in lung epithelial cells was recorded after expression of the cloned channel in oocytes. The level of the mRNA for the Na+ channel was highly increased from fetal to newborn and adult stages. This observation indicates that the increased Na+ reabsorption that occurs at birth as a necessary event to pass to an air-breathing environment is probably associated with control of transcription of this Na+ channel. The human gene for the lung Na+ channel was mapped on chromosome 12p13. Images Fig. 4 PMID:8278374

  5. Morphological, Physiological, and Structural Responses of Two Species of Artemisia to NaCl Stress

    PubMed Central

    Guan, Zhi-Yong; Su, Yi-Ji; Teng, Nian-Jun; Chen, Su-Mei; Sun, Hai-Nan; Li, Chu-Ling; Chen, Fa-Di

    2013-01-01

    Effects of salt stress on Artemisia scoparia and A. vulgaris “Variegate” were examined. A. scoparia leaves became withered under NaCl treatment, whereas A. vulgaris “Variegate” leaves were not remarkably affected. Chlorophyll content decreased in both species, with a higher reduction in A. scoparia. Contents of proline, MDA, soluble carbohydrate, and Na+ increased in both species under salt stress, but A. vulgaris “Variegate” had higher level of proline and soluble carbohydrate and lower level of MDA and Na+. The ratios of K+/Na+, Ca2+/Na+, and Mg2+/Na+ in A. vulgaris “Variegate” under NaCl stress were higher. Moreover, A. vulgaris “Variegate” had higher transport selectivity of K+/Na+ from root to stem, stem to middle mature leaves, and upper newly developed leaves than A. scoparia under NaCl stress. A. vulgaris “Variegate” chloroplast maintained its morphological integrity under NaCl stress, whereas A. scoparia chloroplast lost integrity. The results indicated that A. scoparia is more sensitive to salt stress than A. vulgaris “Variegate.” Salt tolerance is mainly related to the ability of regulating osmotic pressure through the accumulation of soluble carbohydrates and proline, and the gradient distribution of K+ between roots and leaves was also contributed to osmotic pressure adjustment and improvement of plant salt tolerance. PMID:24235883

  6. Alpha adrenergic modulation of the Na/sup +/ pump of canine vascular smooth muscle

    SciTech Connect

    Navran, S.S.; Adair, S.E.; Allen, J.C.; Seidel, C.L.

    1986-03-01

    Some vasoactive agents, eg. beta adrenergic agonists and forskolin, stimulate the Na/sup 7/ pump by a cAMP- dependent mechanism. The authors have now demonstrated that phenylephrine (PE) stimulates the Na/sup 7/ pump in intact blood vessels as quantitated by an increased ouabain-sensitive /sup 86/Rb uptake. The stimulation is dose-dependent (ED/sub 50/, 3 x 10/sup -6/M) and blocked by phentolamine (I/sub 50/, 10/sup -7/M), prazosin (I/sub 50/, 10/sup -8/M) yohimbine (I/sub 50/, 10/sup -6/M) or elevated intracellular Na/sup +/. These data suggest that the Na/sup +/ pump stimulation is mediated through alpha/sub 1/ receptors which produce an influx of extracellular Na/sup +/. In vascular smooth muscle cell cultures PE stimulates the Na/sup +/ pump, but only when cells have been deprived of fetal calf serum (FCS). Since FCS is known to stimulate Na/sup +/influx, in the continuous presence of FCS, these cells may already be Na/sup +/-loaded and therefore refractory to further stimulation by alpha-adrenergic agents. Unlike those vasorelaxants whose mechanism involves stimulation of the Na/sup +/ pump, alpha adrenergic agents are vasoconstrictors and therefore the role of Na/sup +/ pump stimulation in this case may be as a mechanism of feedback inhibition of contractility.

  7. Intracellular Na+ modulates the cAMP-dependent regulation of ion channels in the heart.

    PubMed Central

    Harvey, R D; Jurevicius, J A; Hume, J R

    1991-01-01

    The cAMP-dependent regulation of ion channels was studied by using the whole-cell configuration of the patch clamp technique. In isolated cardiac ventricular myocytes, the beta-adrenergically regulated Cl- current (ICl) exhibited an unusual dependence on Na+, such that replacement of extracellular Na+ with compounds such as tetramethylammonium, choline, Tris, or N-methyl-D-glucamine resulted in a reduction in current amplitude without changing the reversal potential. Replacement of extracellular Na+ with tetramethylammonium also reduced the magnitude of the beta-adrenergically enhanced Ca2+ current and delayed rectifier K+ current, suggesting that removal of Na+ was affecting the cAMP pathway that regulates all three currents. Replacement of extracellular Na+ also reduced ICl that was stimulated by (i) direct activation of adenylate cyclase with forskolin, (ii) inhibition of phosphodiesterase with 3-isobutyl-1-methylxanthine, (iii) exposure to the membrane-permeable cAMP derivative 8-bromoadenosine 3',5'-cyclic monophosphate, or (iv) direct phosphorylation of the channel with protein kinase A catalytic subunit. This suggests that the Na+ dependence is at a point beyond the activation of protein kinase A. The Na+ dependence of ICl regulation could not be explained by changes in intracellular Ca2+. However, the sensitivity of the ICl to changes in extracellular Na+ depended significantly on the intracellular Na+ concentration, suggesting that intracellular Na+ plays an important role in the cAMP-dependent regulation of ion channels. Images PMID:1714581

  8. Formation of titanate nanostructures under different NaOH concentration and their application in wastewater treatment

    SciTech Connect

    Huang Jiquan [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Graduate school of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100049 (China); Cao Yongge, E-mail: caoyongge@fjirsm.ac.c [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Deng Zhonghua; Tong Hao [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

    2011-03-15

    The effects of the concentration of NaOH on the formation and transformation of various titanate nanostructures were studied. With increasing NaOH concentration, three different formation mechanisms were proposed. Nanotubes can only be obtained under moderate NaOH conditions, and should transform into nanowires with prolonged hydrothermal treatment, and their formation rate is accelerated by increasing NaOH concentration. Low concentration of NaOH results in the direct formation of nanowires, while extra high concentration of NaOH leads to the formation of amorphous nanoparticles. Adsorption and photocatalysis studies show that titanate nanowires and nanotubes might be potential adsorbents for the removal of both heavy metal ions and dyes and photocatalysts for the removal of dyes from wastewater. -- Graphical abstract: The morphologies of the titanates depend deeply on the concentration of NaOH. With increasing NaOH concentration, three different formation mechanisms were proposed. The application of these titanate nanostructures in the wastewater treatment was studied. Display Omitted Research highlights: {yields} Effect of NaOH concentration on the structures of various titanates was reported. {yields} Three different formation mechanisms were presented with increasing NaOH concentration. {yields} Various titanates were used as adsorbents/photocatalysts in wastewater treatment.

  9. Mobilization of osmotically inactive Na+ by growth and by dietary salt restriction in rats.

    PubMed

    Schafflhuber, Markus; Volpi, Nicola; Dahlmann, Anke; Hilgers, Karl F; Maccari, Francesca; Dietsch, Peter; Wagner, Hubertus; Luft, Friedrich C; Eckardt, Kai-Uwe; Titze, Jens

    2007-05-01

    The idea that an osmotically inactive Na(+) storage pool exists that can be varied to accommodate states of Na(+) retention and/or Na(+) loss is controversial. We speculated that considerable amounts of osmotically inactive Na(+) are lost with growth and that additional dietary salt excess or salt deficit alters the polyanionic character of extracellular glycosaminoglycans in osmotically inactive Na(+) reservoirs. Six-week-old Sprague-Dawley rats were fed low-salt (0.1%; LS) or high-salt (8%; HS) diets for 1 or 4 wk. At their death, we separated the tissues and determined their Na(+), K(+), and water content. Three weeks of growth reduced the total body Na(+) content relative to dry weight (rTBNa(+)) by 23%. This "growth-programmed" Na(+) loss originated from the bone and the completely skinned and bone-removed carcasses. The Na(+) loss was osmotically inactive (45-50%) or osmotically active (50-55%). In rats aged 10 wk, compared with HS, 4 wk of LS reduced rTBNa(+) by 9%. This dietary-induced Na(+) loss was osmotically inactive ( approximately 50%) and originated largely from the skin, while approximately 50% was osmotically active. LS for 1 wk did not reduce skin Na(+) content. The mobilization of osmotically inactive skin Na(+) with long-term salt deprivation was associated with decreased negatively charged skin glycosaminoglycan content and thereby a decreased water-free Na(+) binding capacity in the extracellular matrix. Our data not only serve to explain discrepant results in salt balance studies but also show that glycosaminoglycans may provide an actively regulated interstitial cation exchange mechanism that participates in volume and blood pressure homeostasis. PMID:17244896

  10. Linking salinity stress tolerance with tissue-specific Na+ sequestration in wheat roots

    PubMed Central

    Wu, Honghong; Shabala, Lana; Liu, Xiaohui; Azzarello, Elisa; Zhou, Meixue; Pandolfi, Camilla; Chen, Zhong-Hua; Bose, Jayakumar; Mancuso, Stefano; Shabala, Sergey

    2015-01-01

    Salinity stress tolerance is a physiologically complex trait that is conferred by the large array of interacting mechanisms. Among these, vacuolar Na+ sequestration has always been considered as one of the key components differentiating between sensitive and tolerant species and genotypes. However, vacuolar Na+ sequestration has been rarely considered in the context of the tissue-specific expression and regulation of appropriate transporters contributing to Na+ removal from the cytosol. In this work, six bread wheat varieties contrasting in their salinity tolerance (three tolerant and three sensitive) were used to understand the essentiality of vacuolar Na+ sequestration between functionally different root tissues, and link it with the overall salinity stress tolerance in this species. Roots of 4-day old wheat seedlings were treated with 100 mM NaCl for 3 days, and then Na+ distribution between cytosol and vacuole was quantified by CoroNa Green fluorescent dye imaging. Our major observations were as follows: (1) salinity stress tolerance correlated positively with vacuolar Na+ sequestration ability in the mature root zone but not in the root apex; (2) contrary to expectations, cytosolic Na+ levels in root meristem were significantly higher in salt tolerant than sensitive group, while vacuolar Na+ levels showed an opposite trend. These results are interpreted as meristem cells playing a role of the “salt sensor;” (3) no significant difference in the vacuolar Na+ sequestration ability was found between sensitive and tolerant groups in either transition or elongation zones; (4) the overall Na+ accumulation was highest in the elongation zone, suggesting its role in osmotic adjustment and turgor maintenance required to drive root expansion growth. Overall, the reported results suggest high tissue-specificity of Na+ uptake, signaling, and sequestration in wheat roots. The implications of these findings for plant breeding for salinity stress tolerance are discussed. PMID:25750644

  11. NaOH-modified ceramic honeycomb with enhanced formaldehyde adsorption and removal performance.

    PubMed

    Yu, Jiaguo; Li, Xinyang; Xu, Zhihua; Xiao, Wei

    2013-09-01

    NaOH-modified ceramic honeycombs (Na-CH) were simply prepared by impregnating ceramic honeycombs (CH) into NaOH aqueous solution. It was clearly shown that the surface modification incurs higher specific surface area and smaller grain sizes of the CH without destruction of their integrity. Moreover, the introduced surface NaOH can trigger Cannizzaro disproportionation of surface-absorbed formaldehyde (HCHO) on Na-CH, resulting in catalytic transformation of HCHO into less-toxic formate and methoxy salts. The NaOH concentration during impregnating treatment has a great influence on HCHO adsorption and removal efficiency, while the impregnation time and temperature have little influence on the efficiency. When the CH was impregnated in 1 M NaOH aqueous solution for 0.5 h at room temperature, the HCHO removal efficiency at ambient temperature can reach about 80% with an initial HCHO concentration of 250 ppm. Moreover, the used Na-CH can be facilely regenerated via 1 min blow using a common electric hair dryer, with the generation of less toxic HCOOH and CH3OH and recovery of NaOH. Using such a mild, fast, and practical regeneration method, the regenerated Na-CH showed slight degradation in adsorption and removal capability toward HCHO. The enhanced performance of Na-CH obtained was attributed to the presence of NaOH and increase of specific surface area and surface hydroxyl groups. Considering no demand of noble metal for HCHO removal at ambient temperature and practical reusable capability of Na-CH under mild conditions, this work may provide some new insights into the design and fabrication of advanced catalysts for indoor air purification. PMID:23895134

  12. Low Momentum Particle Detector at the NA61/SHINE Experiment

    NASA Astrophysics Data System (ADS)

    Marton, K.

    2014-06-01

    p+A interactions has an important role in understanding hadronic physics. In earlier experiments, it was found that the centrality of such collisions is related to the number of slow ("grey") nucleons which are produced in the break-up of the nucleus. By detecting and identifying these low momentum particles in the typical kinetic energy range of 20-100MeV, one can determine the centrality of individual events. The NA61/SHINE at CERN SPS is a fixed-target experiment with rich physics program which contains the study of p+A collisions. For this experiment, the Low Momentum Particle Detector (LMPD) has been built which is a Time Projection Chamber with absorber layers in the gas volume. The detector has a key feature, namely it can positively identify protons by simultaneous measurement of ionization and range, in the momentum interval of 0.1-0.25 GeV/c. The LMPD was tested in 2011 at CERN and was used as a centrality detector in the p+Pb run of NA61 in 2012.

  13. Covering surface nanobubbles with a NaCl nanoblanket.

    PubMed

    Berkelaar, Robin P; Zandvliet, Harold J W; Lohse, Detlef

    2013-09-10

    By letting a NaCl aqueous solution of low (0.01 M) concentration evaporate on a highly oriented pyrolytic graphite (HOPG) surface, it is possible to form a thin film of salt. However, pre-existing surface nanobubbles prevent the homogeneous coverage of the surface with the salt, keeping the footprint areas on the substrate pristine. Comparing the surface nanobubbles in the salt solution with their associated footprint after drying, provides information on the shrinkage of nanobubbles during the hours-long process of drying the liquid film. At a slightly higher NaCl concentration and thus salt layer thickness, the nanobubbles are covered with a thin blanket of salt. Once the liquid film has evaporated until a water film remains that is smaller than the height of the nanobubbles, the blanket of salt cracks and unfolds into a flower-like pattern of salt flakes that is located at the rim of the nanobubble footprint. The formation of a blanket of salt covering the nanobubbles is likely to considerably or even completely block the gas out-flux from the nanobubble, partially stabilizing the nanobubbles against dissolution. PMID:23937683

  14. Molecular simulation study of hydrated Na-rectorite.

    PubMed

    Zhou, Jinhong; Boek, Edo S; Zhu, Jianxi; Lu, Xiancai; Sprik, Michiel; He, Hongping

    2015-02-17

    The swelling behavior of clay minerals is an important issue in industrial processes and environmental applications. Mixed-layer clay minerals containing a smectite fraction, such as rectorite, are neglected even though they could swell and exist in nature widely. The hydration of rectorite has not been well comprehended even though they are meaningful to mineralogy and industry. This study combines molecular dynamics (MD) and Monte Carlo (MC) simulations to disclose the swelling behavior of rectorite and compare with montmorillonite. From grand canonical Monte Carlo (GCMC) and MD simulations, we obtain swelling curves and swelling free-energy curves of rectorite with a relative humidity of 100%. With the comparisons of swelling free-energy minima, we find that the bilayer hydrate of Na-rectorite is more thermodynamically stable than the monolayer hydrate, which is similar to Na-montmorillonite. However, the interlayer sodium ions in rectorite show an asymmetrical distribution quite different from the symmetrical distribution in montmorillonite. Because of unequal layer charges between the smectite part and illite part of retorite, sodium ions prefer to distribute close to the illite part surface. PMID:25625308

  15. Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current

    PubMed Central

    Vornanen, Matti; Hassinen, Minna; Haverinen, Jaakko

    2011-01-01

    Evolutionary origin and physiological significance of the tetrodotoxin (TTX) resistance of the vertebrate cardiac Na+ current (INa) is still unresolved. To this end, TTX sensitivity of the cardiac INa was examined in cardiac myocytes of a cyclostome (lamprey), three teleost fishes (crucian carp, burbot and rainbow trout), a clawed frog, a snake (viper) and a bird (quail). In lamprey, teleost fishes, frog and bird the cardiac INa was highly TTX-sensitive with EC50-values between 1.4 and 6.6 nmol·L?1. In the snake heart, about 80% of the INa was TTX-resistant with EC50 value of 0.65 ?mol·L?1, the rest being TTX-sensitive (EC50 = 0.5 nmol·L?1). Although TTX-resistance of the cardiac INa appears to be limited to mammals and reptiles, the presence of TTX-resistant isoform of Na+ channel in the lamprey heart suggest an early evolutionary origin of the TTX-resistance, perhaps in the common ancestor of all vertebrates. PMID:22163193

  16. Correction of the Caulobacter crescentus NA1000 Genome Annotation

    PubMed Central

    Ely, Bert; Scott, LaTia Etheredge

    2014-01-01

    Bacterial genome annotations are accumulating rapidly in the GenBank database and the use of automated annotation technologies to create these annotations has become the norm. However, these automated methods commonly result in a small, but significant percentage of genome annotation errors. To improve accuracy and reliability, we analyzed the Caulobacter crescentus NA1000 genome utilizing computer programs Artemis and MICheck to manually examine the third codon position GC content, alignment to a third codon position GC frame plot peak, and matches in the GenBank database. We identified 11 new genes, modified the start site of 113 genes, and changed the reading frame of 38 genes that had been incorrectly annotated. Furthermore, our manual method of identifying protein-coding genes allowed us to remove 112 non-coding regions that had been designated as coding regions. The improved NA1000 genome annotation resulted in a reduction in the use of rare codons since noncoding regions with atypical codon usage were removed from the annotation and 49 new coding regions were added to the annotation. Thus, a more accurate codon usage table was generated as well. These results demonstrate that a comparison of the location of peaks third codon position GC content to the location of protein coding regions could be used to verify the annotation of any genome that has a GC content that is greater than 60%. PMID:24621776

  17. Paleothermometry of NaCl as evidenced from thermoluminescence data

    NASA Astrophysics Data System (ADS)

    Gartia, R. K.

    2009-09-01

    The firing temperature of ancient ceramic artifacts, i.e. the paleothermometry of these materials has been estimated by various techniques including thermoluminescence (TL) and, more recently, Optically Stimulated Luminescence (OSL) where the OSL response of quartz to firing temperature is used. In this work we report the paleothermometry of sodium chloride (NaCl) by studying the TL response of the material as a function of annealing temperatures in the range of 100-500 °C. Annealing/measurement has been done in a commercial TL/OSL reader (Model No. Risø TL/OSL reader TL-DA-15) in a nitrogen atmosphere. Sodium chloride (NaCl) has been selected as the candidate to test the feasibility of the technique since in this system TL peaks are correlated with the thermal annealing of F-centers unlike the case of quartz where a one to one correlation with all the glow peaks and thermal annealing of defects has not been possible.

  18. MINOS Calibration and NA49 Hadronic Production Studies

    SciTech Connect

    Morse, Robert James

    2003-08-01

    An overview of the current status of the Main Injector Neutrino Oscillation Search (MINOS) is presented. MINOS is a long-baseline experiment with two detectors situated in North America. The near detector is based at the emission point of the NuMI beam at Fermilab, Chicago, the far detector is 735 km downstream in a disused iron mine in Soudan, Minnesota. A third detector, the calibration detector, is used to cross-calibrate these detectors by sampling different particle beams at CERN. A detailed description of the design and construction of the light-injection calibration system is included. Also presented are experimental investigations into proton-carbon collisions at 158 GeV/c carried out with the NA49 experiment at CERN. The NA49 experiment is a Time Projection Chamber (TPC) based experiment situated at CERN's North Area. It is a well established experiment with well known characteristics. The data gained from this investigation are to be used to parameterize various hadronic production processes in accelerator and atmospheric neutrino production. These hadronic production parameters will be used to improve the neutrino generation models used in calculating the neutrino oscillation parameters in MINOS.

  19. FXYD Proteins: New Tissue-Specific Regulators of the Ubiquitous Na,K-ATPase

    NSDL National Science Digital Library

    Gilles Crambert (University of Lausanne; Institute of Pharmacology and Toxicology REV)

    2003-01-21

    The Na,K-ATPase is a plasma membrane enzyme that is responsible for maintaining the Na+ and K+ gradients between the intra- and extracellular milieu of animal cells. It consists of a catalytic ? subunit and a regulatory ? subunit. Na,K-ATPase transports Na+ out of the cell and K+ into the cell against their respective chemical gradients by using energy derived from the hydrolysis of ATP. Maintenance of the Na+ and K+ gradients by the Na,K-ATPase is essential for basic cellular homeostasis as well as for specialized functions of various tissues. Rigorous control of the Na+ and K+ gradients by Na,K-ATPase is necessary for preservation of cell volume, maintenance of membrane potential, and activity of secondary transporters that provide the cell with nutrients or regulate cellular solute concentrations. Moreover, in renal epithelial cells, the Na,K-ATPase, exclusively located in the basolateral membrane, is the driving force for the Na+ reabsorption that maintains extracellular volume and, hence, blood pressure. In addition, in heart and skeletal muscle, the activity of Na,K-ATPase is tightly coupled to the activity of a Na+/Ca2+-exchanger that controls muscle contraction. Finally, in the nervous system, Na,K-ATPase contributes to the re-establishment of the basal Na+ and K+ gradients both during action potentials and consequent to neuronal excitation. The Na,K-ATPase must be finely regulated to fulfil its important tasks under changing physiological conditions. Tissue-specific differences in Na,K-ATPase activity are achieved by the expression of four ? and three ? isoforms, which potentially can form 12 Na,K-ATPase isozymes with different functional properties. Moreover, various hormones and neurotransmitters are involved in the short- and long-term control of Na,K-ATPase; they regulate its activity and/or expression through protein kinase phosphorylation or transcriptional control. In this review, we discuss a novel regulatory mechanism of Na,K-ATPase that is mediated by the interaction of Na,K-ATPase with small membrane proteins of the FXYD family that so far have been considered as channels or regulators of ion channels. The FXYD proteins FXYD1 through FXYD7 exhibit tissue-specific distribution. FXYD1 (phospholemman) in heart and skeletal muscle, FXYD2 (the ? subunit of Na,K-ATPase) and FXYD4 [corticosteroid hormone-induced factor (CHIF)] in the kidney, and FXYD7 in the brain associate preferentially with the Na,K-ATPase ?1-?1 isozyme and modulate its transport properties in a way that conforms to tissue-specific requirements. Thus, FXYD proteins contribute to proper handling of Na+ and K+ by the most widely expressed Na,K-ATPase ?1-?1 isozymes, and ensure correct function in such mechanisms as renal Na+ reabsorption, muscle contraction, and neuronal excitability

  20. SLC4A11 is an EIPA-sensitive Na(+) permeable pHi regulator.

    PubMed

    Ogando, Diego G; Jalimarada, Supriya S; Zhang, Wenlin; Vithana, Eranga N; Bonanno, Joseph A

    2013-10-01

    Slc4a11, a member of the solute linked cotransporter 4 family that is comprised predominantly of bicarbonate transporters, was described as an electrogenic 2Na(+)-B(OH)4(-) (borate) cotransporter and a Na(+)-2OH(-) cotransporter. The goal of the current study was to confirm and/or clarify the function of SLC4A11. In HEK293 cells transfected with SLC4A11 we tested if SLC4A11 is a: 1) Na(+)-HCO3(-) cotransporter, 2) Na(+)-OH(-)(H(+)) transporter, and/or 3) Na(+)-B(OH)4(-) cotransporter. CO2/HCO3(-) perfusion yielded no significant differences in rate or extent of pHi changes or Na(+) flux in SLC4A11-transfected compared with control cells. Similarly, in CO2/HCO3(-), acidification on removal of Na(+) and alkalinization on Na(+) add back were not significantly different between control and transfected indicating that SLC4A11 does not have Na(+)-HCO3(-) cotransport activity. In the absence of CO2/HCO3(-), SLC4A11-transfected cells showed higher resting intracelllular Na(+) concentration ([Na(+)]i; 25 vs. 17 mM), increased NH4(+)-induced acidification and increased acid recovery rate (160%) after an NH4 pulse. Na(+) efflux and influx were faster (80%) following Na(+) removal and add back, respectively, indicative of Na(+)-OH(-)(H(+)) transport by SLC4A11. The increased alkalinization recovery was confirmed in NHE-deficient PS120 cells demonstrating that SLC4A11 is a bonafide Na(+)-OH(-)(H(+)) transporter and not an activator of NHEs. SLC4A11-mediated H(+) efflux is inhibited by 5-(N-ethyl-N-isopropyl) amiloride (EIPA; EC50: 0.1 ?M). The presence of 10 mM borate did not alter dpHi/dt or ?pH during a Na(+)-free pulse in SLC4A11-transfected cells. In summary our results show that SLC4A11 is not a bicarbonate or borate-linked transporter but has significant EIPA-sensitive Na(+)-OH(-)(H(+)) and NH4(+) permeability. PMID:23864606

  1. Synergistic Na-storage reactions in Sn4P3 as a high-capacity, cycle-stable anode of Na-ion batteries.

    PubMed

    Qian, Jiangfeng; Xiong, Ya; Cao, Yuliang; Ai, Xinping; Yang, Hanxi

    2014-01-01

    Room-temperature Na-ion batteries have attracted great interest as a low cost and environmentally benign technology for large scale electric energy storage, however their development is hindered by the lack of suitable anodic host materials. In this paper, we described a green approach for the synthesis of Sn4P3/C nanocomposite and demonstrated its excellent Na-storage performance as a novel anode of Na-ion batteries. This Sn4P3/C anode can deliver a very high reversible capacity of 850 mA h g(-1) with a remarkable rate capability with 50% capacity output at 500 mA g(-1) and can also be cycled with 86% capacity retention over 150 cycles due to a synergistic Na-storage mechanism in the Sn4P3 anode, where the Sn nanoparticles act as electronic channels to enable electrochemical activation of the P component, while the elemental P and its sodiated product Na3P serve as a host matrix to alleviate the aggregation of the Sn particles during Na insertion reaction. This mechanism may offer a new approach to create high capacity and cycle-stable alloy anodes for Na-ion batteries and other electrochemical energy storage applications. PMID:24611662

  2. Propagation speed in myelinated nerve. II. Theoretical dependence on external Na and on temperature.

    PubMed

    Hardy, W L

    1973-10-01

    The Hodgkin-Huxley (H.H.) equations modified by Dodge for Rana pipiens myelinated nerve have been solved to determine how well the theory predicts the effects of changes of temperature and [Na(+)](0) on propagation. Conduction speed theta was found to have an approximately exponential dependence on temperature as was found experimentally, but the theoretical temperature coefficient (Q(10)) was low; 1.5 compared with the experimental finding of 2.95. theta was found to be a linear function of log ([Na(+)](0)) in contrast to the experimental finding of a square root dependence on [Na(+)](0). theta is 50% greater at one-fourth normal [Na(+)](0) than the theory predicts. The difference between the theoretical theta([Na(+)](0)) and the experimental theta([Na(+)](0)) is probably due to an imprecisely known variation of parameters and not to a fundamental inadequacy of the theory. PMID:4542941

  3. Photoemission study of the electronic structure and charge density waves of Na?Ti?Sb?O

    DOE PAGESBeta

    Tan, S. Y.; Jiang, J.; Ye, Z. R.; Niu, X. H.; Song, Y.; Zhang, C. L.; Dai, P. C.; Xie, B. P.; Lai, X. C.; Feng, D. L.

    2015-04-30

    The electronic structure of Na?Ti?Sb?O single crystal is studied by photon energy and polarization dependent angle-resolved photoemission spectroscopy (ARPES). The obtained band structure and Fermi surface agree well with the band structure calculation of Na?Ti?Sb?O in the non-magnetic state, which indicates that there is no magnetic order in Na?Ti?Sb?O and the electronic correlation is weak. Polarization dependent ARPES results suggest the multi-band and multi-orbital nature of Na?Ti?Sb?O. Photon energy dependent ARPES results suggest that the electronic structure of Na?Ti?Sb?O is rather two-dimensional. Moreover, we find a density wave energy gap forms below the transition temperature and reaches 65 meV atmore »7 K, indicating that Na?Ti?Sb?O is likely a weakly correlated CDW material in the strong electron-phonon interaction regime. (author)« less

  4. NaSrCo2F7, a Co(2+) pyrochlore antiferromagnet.

    PubMed

    Krizan, J W; Cava, R J

    2015-07-29

    We report the crystal growth, by the Bridgeman-Stockbarger method, and the basic magnetic properties of a new cobalt-based pyrochlore, NaSrCo2F7. Single-crystal structure determination shows that Na and Sr are completely disordered on the non-magnetic large atom A sites, while magnetic [Formula: see text] Co(2+) fully occupies the pyrochlore lattice B sites. NaSrCo2F7 displays strong antiferromagnetic interactions ([Formula: see text]), a large effective moment ([Formula: see text]), and no spin freezing until 3?K. Thus, NaSrCo2F7 is a geometrically frustrated antiferromagnet with a frustration index [Formula: see text]. Ac susceptibility, dc susceptibility, and heat capacity are utilized to characterize the spin freezing. We argue that NaSrCo2F7 and the related material NaCaCo2F7 are examples of frustrated pyrochlore antiferromagnets with weak bond disorder. PMID:26154596

  5. Na(+) transport in glycophytic plants: what we know and would like to know.

    PubMed

    Craig Plett, Darren; Møller, Inge Skrumsager

    2010-04-01

    Soil salinity decreases the growth rate of plants and can severely limit the productivity of crop plants. The ability to tolerate salinity stress differs widely between species of plants as well as within species. As an important component of salinity tolerance, a better understanding of the mechanisms of Na(+) transport will assist in the development of plants with improved salinity tolerance and, importantly, might lead to increased yields from crop plants growing in challenging environments. This review summarizes the current understanding of the components of Na(+) transport in glycophytic plants, including those at the soil to root interface, transport of Na(+) to the xylem, control of Na(+) loading in the stele and partitioning of the accumulated Na(+) within the shoot and individual cells. Using this knowledge, strategies to modify Na(+) transport and engineer plant salinity tolerance, as well as areas of research which merit particular attention in order to further improve the understanding of salinity tolerance in plants, are discussed. PMID:19968828

  6. Photoemission study of the electronic structure and charge density waves of Na?Ti?Sb?O

    DOE PAGESBeta

    Tan, S. Y. [Science and Technology on Surface Physics and Chemistry Lab., Mianyang (China); Fundan Univ., Shanghai (China); Jiang, J. [Fundan Univ., Shanghai (China); Nanjing Univ., Nanjing (China); Ye, Z. R. [Fundan Univ., Shanghai (China); Niu, X. H. [Fundan Univ., Shanghai (China); Nanjing Univ., Nanjing (China); Song, Y. [Rice Univ., Houston, TX (United States); Zhang, C. L. [Rice Univ., Houston, TX (United States); Univ. of Tennessee, Knoxville, TN (United States); Dai, P. C. [Rice Univ., Houston, TX (United States); Xie, B. P. [Fundan Univ., Shanghai (China); Nanjing Univ., Nanjing (China); Lai, X. C. [Science and Technology on Surface Physics and Chemistry Lab., Mianyang (China); Feng, D. L. [Fundan Univ., Shanghai (China); Nanjing Univ., Nanjing (China)

    2015-04-30

    The electronic structure of Na?Ti?Sb?O single crystal is studied by photon energy and polarization dependent angle-resolved photoemission spectroscopy (ARPES). The obtained band structure and Fermi surface agree well with the band structure calculation of Na?Ti?Sb?O in the non-magnetic state, which indicates that there is no magnetic order in Na?Ti?Sb?O and the electronic correlation is weak. Polarization dependent ARPES results suggest the multi-band and multi-orbital nature of Na?Ti?Sb?O. Photon energy dependent ARPES results suggest that the electronic structure of Na?Ti?Sb?O is rather two-dimensional. Moreover, we find a density wave energy gap forms below the transition temperature and reaches 65 meV at 7 K, indicating that Na?Ti?Sb?O is likely a weakly correlated CDW material in the strong electron-phonon interaction regime. (author)

  7. The role of NaYF4 nanoparticles in inverted polymer solar cells

    NASA Astrophysics Data System (ADS)

    Guo, Wenbin; Jiang, Huimin; Liu, Chunyu; He, Yeyuan; Zhang, Xinyuan

    2014-07-01

    NaYF4 nanoparticles are doped into PCDTBT:PCBM blend as a dual function additive to improve light absorption of inverted polymer solar cells. The dependence of device performance on NaYF4 in the blend film is investigated. The results show that the short-circuit current density is apparently enhanced by doping NaYF4 into the active layer while maintaining the open-circuit voltage and fill factor, leading to an increase in power conversion efficiency. NaYF4 maybe play two kinds of role for light absorption enhancement. Up-conversion (UC) emission from Y3+ is observed. The scattering effect of NaYF4 nanoparticles (NPs) enhances the light absorption in visible region. The performance of polymer solar cell doped with NaYF4 is compared with that of undoped. The concept of integrating nanoparticles into active layer suggests a promising and practical pathway for improving absorption of polymer solar cells.

  8. 29Na: defining the edge of the island of inversion for Z=11.

    PubMed

    Tripathi, Vandana; Tabor, S L; Mantica, P F; Hoffman, C R; Wiedeking, M; Davies, A D; Liddick, S N; Mueller, W F; Otsuka, T; Stolz, A; Tomlin, B E; Utsuno, Y; Volya, A

    2005-04-29

    The low-energy level structure of the exotic Na isotopes (28,29)Na has been investigated through beta-delayed gamma spectroscopy. The N=20 isotones for Z=10-12 are considered to belong to the "island of inversion" where intruder configurations dominate the ground state wave function. However, it is an open question as to where and how the transition from normal to intruder dominated configurations happens in an isotopic chain. The present work, which presents the first detailed spectroscopy of (28,29)Na, clearly demonstrates that such a transition in the Na isotopes occurs between 28Na (N=17) and 29Na (N=18), supporting the smaller N=20 shell gap in neutron-rich sd shell nuclei. The evidence for inverted shell structure is found in beta-decay branching ratios, intruder dominated spectroscopy of low-lying states, and shell model analysis. PMID:15904217

  9. Modulation of intracellular Na+ activity and cardiac force by norepinephrine and Ca2+.

    PubMed

    Lee, C O; Vassalle, M

    1983-01-01

    The actions of norepinephrine and high calcium on the electrical, mechanical, and intracellular sodium ion activities were studied in electrically driven canine cardiac Purkinje fibers under different conditions. It was found that norepinephrine and high calcium decrease intracellular sodium ion activity (aiNa). The exposure to either agent is followed by a transient decline of force that correlates with the lower aiNa. Inhibition of the Na+ -K+ pump by strophanthidin reduces or abolishes the decrease in aiNa by norepinephrine but not that by high calcium. It is concluded that norepinephrine and high calcium both decrease aiNa and thereby the contractile force but (unlike high calcium) norepinephrine acts through the stimulation of the Na+ -K+ pump. PMID:6295176

  10. Improved assessment of cartilage repair tissue using fluid-suppressed 23Na inversion recovery MRI at 7 Tesla: preliminary results

    PubMed Central

    Madelin, Guillaume; Sherman, Orrin H.; Strauss, Eric J.; Xia, Ding; Recht, Michael P.; Jerschow, Alexej; Regatte, Ravinder R.

    2013-01-01

    Objectives To evaluate cartilage repair and native tissue using a three-dimensional (3D), radial, ultra-short echo time (UTE) 23Na MR sequence without and with an inversion recovery (IR) preparation pulse for fluid suppression at 7 Tesla (T). Methods This study had institutional review board approval. We recruited 11 consecutive patients (41.5±11.8 years) from an orthopaedic surgery practice who had undergone a knee cartilage restoration procedure. The subjects were examined postoperatively (median=26 weeks) with 7-T MRI using: proton-T2 (TR/TE=3,000 ms/60 ms); sodium UTE (TR/TE=100 ms/0.4 ms); fluid-suppressed, sodium UTE adiabatic IR. Cartilage sodium concentrations in repair tissue ([Na+]R), adjacent native cartilage ([Na+]N), and native cartilage within the opposite, non-surgical compartment ([Na+]N2) were calculated using external NaCl phantoms. Results For conventional sodium imaging, mean [Na+]R, [Na+]N, [Na+]N2 were 177.8±54.1 mM, 170.1±40.7 mM, 172.2±30 mM respectively. Differences in [Na+]R versus [Na+]N (P=0.59) and [Na+]N versus [Na+]N2 (P=0.89) were not significant. For sodium IR imaging, mean [Na+]R, [Na+]N, [Na+]N2 were 108.9±29.8 mM, 204.6±34.7 mM, 249.9± 44.6 mM respectively. Decreases in [Na+]R versus [Na+]N (P=0.0.0000035) and [Na+]N versus [Na+]N2 (P=0.015) were significant. Conclusions Sodium IR imaging at 7 T can suppress the signal from free sodium within synovial fluid. This may allow improved assessment of [Na+] within cartilage repair and native tissue. PMID:22350437

  11. Na8Au9.8(4)Ga7.2 and Na17Au15.87(2)Ga46.63: The diversity of pseudo 5-fold 0 Cross Mark symmetries in the Na-Au-Ga system

    SciTech Connect

    Smetana, Volodymyr [Ames Laboratory; Corbett, John D.; Miller, Gordon J. [Ames Laboratory

    2013-08-29

    The Na-rich part (similar to 30% Na) of the Na-Au-Ga system between NaAu2, NaGa4, and Na(22)Ga39 has been found to contain the ternary phases NasAug(8)(4)Ga-7.2 (I) and NavAu(5.87(2))Ga46.63 (II), according to the results of single crystal X-ray diffraction measurements. I is orthorhombic, Cmcm, a= 5.3040(1), b=24.519(5), c=14.573(3) A, and contains a network of clusters with local 5-fold symmetry along the a-axis. Such clusters are frequent building units in decagonal quasicrystals and their approximants. II is rhombohedral, a =16.325(2), c=35.242(7) A, and contains building blocks that are structurally. identical to the Bergman-type clusters as well as fused icosahedral units known with active metals, triels and late transition elements. II also contains a polycationic network with elements of the clathrate V type structure. Tight-binding electronic structure calculations using linear muffin-tin-orbital (LMTO) methods on idealized models of I and II indicate that both compounds are metallic with evident pseudogaps at the corresponding Fermi levels. The overall Hamilton bond populations are generally dominated by Au-Ga and Au-Au bonds in I and by Ga-Ga bonds in II; moreover, the Na-Au and Na-Ga contributions in I are unexpectedly large, 20% of the total. A similar involvement of sodium in covalent bonding has also been found in the electron-richer i-Nai(3)Aui(2)Gai(5) quasicrystal approximant. (C) 2013 Elsevier Inc. All rights reserved.

  12. Quaternary pnictides with complex, noncentrosymmetric structures. Synthesis and structural characterization of the new Zintl phases Na11Ca2Al3Sb8, Na4CaGaSb3, and Na15Ca3In5Sb12.

    PubMed

    Wang, Yi; Stoyko, Stanislav; Bobev, Svilen

    2015-02-16

    Three new Zintl phases, Na11Ca2Al3Sb8, Na4CaGaSb3, and Na15Ca3In5Sb12, have been synthesized by solid-state reactions, and their structures have been determined by single-crystal X-ray diffraction. Na11Ca2Al3Sb8 crystallizes with its own structure type (Pearson index oP48) with the primitive orthorhombic space group Pmn2(1) (No. 31). The structure is best viewed as [Al3Sb8](15-) units of fused AlSb4 tetrahedra, a novel type of Zintl ion, with Na(+) and Ca(2+) cations that solvate them. Na4CaGaSb3 also crystallizes in its own type with the primitive monoclinic space group Pc (No. 7; Pearson index mP36), and its structure boasts one-dimensional [GaSb3](6-) helical chains of corner-shared GaSb4 tetrahedra. The third new compound, Na15Ca3In5Sb12, crystallizes with the recently reported K2BaCdSb2 structure type (space group Pmc2(1); Pearson index oP12). The Na15Ca3In5Sb12 structure is based on polyanionic layers made of corner-shared InSb4 tetrahedra. Approximately one-sixth of the In sites are vacant in a statistical manner. All three structures exhibit similarities to the TiNiSi structure type, and the corresponding relationships are discussed. Electronic band structure calculations performed using the tight-binding linear muffin-tin orbital atomic sphere approximation method show small band gaps for all three compounds, which suggests intrinsic semiconducting behavior for these materials. PMID:25650866

  13. Expression and localization of Na +\\/H + exchangers in rat central nervous system

    Microsoft Academic Search

    E Ma; G. G Haddad

    1997-01-01

    Neurons in the central nervous system regulate their intracellular pH using particular membrane proteins of which two, namely the Na+-dependent Cl?\\/HCO3? exchanger and the Na+\\/H+ exchanger, are essential. In this study we examined messenger RNA expression and distribution of Na+\\/H+ exchanger in the newborn rat central nervous system and with maturation using Northern blot analysis and in situ hybridization. Our

  14. Effect of rare earth ions on the phase transition of Na2SO4 crystals

    Microsoft Academic Search

    Masatoshi Ohta; Masakazu Sakaguchi

    1991-01-01

    The V &rlarr2; I phase transition of Na2SO4 crystals was investigated on a sample of pure Na2SO4 and on rare-earth-ion (Ln3+ = La3+, Eu3+, Tm3+)-doped Na2SO4 samples in various ambient gases (O2, N2, NH3) with high temperature X-ray diffraction and differential thermal analysis. On heating in N2 flow, the initiating temperature for the V --> I transition was lowered by

  15. ANP inhibits Na+-H+ antiport in proximal tubular brush border membrane: Role of dopamine

    Microsoft Academic Search

    Joseph Winaver; John C Burnett; Gertrude M Tyce; Thomas P Dousa

    1990-01-01

    ANP inhibits Na+-H+ antiport in proximal tubular brush border membrane: Role of dopamine.2 Infusion of ANP to rats results in an inhibition of Na+-H+ antiport and Na+-Pi symport in brush border membrane vesicles (BBMV) prepared from kidneys of these animals (J Clin Invest 75:1983). iln the present study we investigated the intrarenal mechanism by which infused ANP elicits these changes

  16. Role of ClO 4 ? in breakdown of tin passivity in NaOH solutions

    Microsoft Academic Search

    Hamdy H. Hassan; Sayed S. Abd El Rehim; Nobl F. Mohamed

    2002-01-01

    The anodic behaviour of a tin electrode in NaOH solutions containing different concentrations of NaClO4 was studied by employing potentiodynamic, potential transient under constant current density methods and complemented with scanning electron microscopy (SEM). In perchlorate-free NaOH solutions, the E\\/i response exhibits active\\/passive transition. The active region involves two anodic peaks corresponding to the formation of Sn(II) and Sn(IV) species

  17. Alleviation of NaCl-induced Effects on Chlorella vulgaris and Chlorococcum humicola by Riboflavin Application

    Microsoft Academic Search

    M. H. M. ABDEL-RAHMAN; R. M. ALI; H. A. SAID

    The interactive effect of NaCl and riboflavin was investigated on the growth and other physiological parameters of Chlorella vulgaris Beij. and Chlorococcum humicola (Näg.) Rab. Low to moderate salinities (50 and 100 mM NaCl) stimulated the growth of both the species while higher levels (150-250 mM NaCl) reduced the growth of C. humicola only. Application of riboflavin led to a

  18. Molecular Cloning and Functional Expression of the Bumetanide-Sensitive Na-K-Cl Cotransporter

    Microsoft Academic Search

    Jian-Chao Xu; Christian Lytle; Tracey T. Zhu; John A. Payne; Edward Benz Jr.; Bliss Forbush III

    1994-01-01

    By mediating the coupled movement of Na, K, and Cl ions across the plasma membrane of most animal cells, the bumetanide-sensitive Na-K-Cl cotransporter (NKCC) plays a vital role in the regulation of ionic balance and cell volume. The transporter is a central element in the process of vectorial salt transport in secretory and absorptive epithelia. A cDNA encoding a Na-K-Cl

  19. Regulation of NaCl absorption in rabbit proximal colon in vitro

    Microsoft Academic Search

    J. H. Sellin; R. De Siognie

    1987-01-01

    Ion transport in rabbit proximal colon (PC) in vitro is dominated by a Na-Cl cotransport system stimulated by epinephrine. To further characterize the regulation of Na-Cl transport, the authors tested the effects of specific adrenergic agonists on ion fluxes under short-circuit conditions. Additionally, they tested the effects of the transport inhibitors bumetanide, furosemide, and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS). Basal Na and

  20. A Search for a Missing Jpi=3\\/2+ level in 21Na

    Microsoft Academic Search

    J. Dubois; H. Odelius; S. O. Berglund

    1972-01-01

    The 20Ne(3He,d)21Na reaction has been studied at 16 MeV bombarding energy. The emitted deuterons have been analysed in a double focusing magnet. Levels in 21Na were deduced. Furthermore the 20Ne(p,gamma)21Na reaction has been investigated using a 44 cm3 Ge(Li) detector. Gamma ray branching ratios and life times have been measured at the 1 169, 1 311 and 1 504 keV

  1. Microwave Versus Conventional-Hydrothermal Synthesis of NaY Zeolite

    Microsoft Academic Search

    Hiroaki Katsuki; Sachiko Furuta; Sridhar Komarneni

    2001-01-01

    This paper focuses on the synthesis of NaY zeolite crystals by using microwave-hydrothermal (M-H) processing. NaY zeolites were synthesized from colloidal silica, sodium aluminate, sodium hydroxide and deionized water at 100°C, and some properties were studied. NaY zeolite crystals with high surface area, in the range of 439 to 716 m2\\/g, have been prepared at 100°C for 1 to 3

  2. Tensile behaviours of some high performance filaments after NaOH treatment

    Microsoft Academic Search

    Huang Gu

    2008-01-01

    Quartz, aramid, and glass filaments were treated by NaOH solution with various concentrations and periods. The outward appearance of the treated filaments was shown.The investigation revealed that higher density of NaOH solution and prolonged treating time would cause accelerated degradation of the aramid filament; when different NaOH concentrations were involved, the decrease rate of the quartz fibre strength after 3

  3. Hierarchy of mechanisms involved in generating Na\\/K-ATPase polarity in MDCK epithelial cells

    Microsoft Academic Search

    Robert W. Mays; Kathleen A. Siemers; Benjamin A. Fritz; Anson W. Lowe; Gerrit van Meer

    1995-01-01

    We have studied mechanisms involved in generating a polarized distribution of Na\\/K-ATPase in the basal-lateral membrane of two clones of MDCK II cells. Both clones exhibit polarized distributions of marker proteins of the apical and basal-lateral mem- branes, including Na\\/K-ATPase, at steady state. Newly synthesized Na\\/K-ATPase, however, is delivered from the Golgi complex to both apical and basal-lateral membranes of

  4. Above threshold dissociation of LiNa +: monitoring an avoided crossing with femtosecond spectroscopy

    NASA Astrophysics Data System (ADS)

    Magnier, S.; Toniolo, A.

    2001-04-01

    Computer simulations of one- and two-color experiments in above threshold dissociation (ATD) are reported for the first heteronuclear alkali ion LiNa +. We focus on the 1 2? +?1 2??4,5 2? + process, with dissociation to Li ++Na(3p) or Li(3s)+Na +. The product yields are determined by the presence of an avoided crossing between the 4 and 5 2? + potential curves, according to the frequency and delay of the second laser pulse.

  5. Enhancing anaerobic biogasification of corn stover through wet state NaOH pretreatment

    Microsoft Academic Search

    Mingxia Zheng; Xiujin Li; Laiqing Li; Xiaojin Yang; Yanfeng He

    2009-01-01

    A new method of wet state (WS) sodium hydroxide (NaOH) was advanced to pretreat corn stover for enhancing biogas production. The results showed that 88% moisture content, 3-day treatment time and ambient temperature (20°C) was appropriate for WS NaOH pretreatment. The NaOH dose of 2% and the loading rate of 65g\\/L were found to be optimal in terms of 72.9%

  6. Obchodovanie na svetových menových trhoch Forex - trading a jeho základné piliere

    Microsoft Academic Search

    Jozef Portašík

    2009-01-01

    Tento ?lánok sa venuje obchodovaniu na svetových menových trhoch Forex, ktorý sa nazýva trading. Venuje sa taktiež aj jeho základným pilierom, ktoré sú nepostrádate?nou sú?as?ou obchodovania každého úspešného obchodníka - tradera. Jedná sa o objasnenie poh?adu na trading ako na biznis. Rozoberá trading z jeho pozitívnych stránok, ale aj varuje pred možnými rizikami. ?alej sa zaoberá základnými piliermi každého úspešného

  7. Molecular simulation of swelling and structure for Na-Wyoming montmorillonite in supercritical CO2

    Microsoft Academic Search

    Nannan Yang; Xiaoning Yang

    2011-01-01

    Gibbs ensemble Monte Carlo (GEMC) simulations were used to study the swelling stability and interlayer structures of Na-montmorillonite clay in supercritical CO2 (scCO2). From the GEMC simulation, it was found that there exist several stable mechanical spacings for Na-Wyoming montmorillonite immersed in scCO2, which are larger than the stable spacing in vacuum condition. The swelling behaviour of Na-montmorillonite clay in

  8. The dissolution of cellulose in NaOH-based aqueous system by two-step process

    Microsoft Academic Search

    Haisong Qi; Quanling Yang; Lina Zhang; Tim Liebert; Thomas Heinze

    2011-01-01

    A new dissolution method, a two-step process, for cellulose in NaOH\\/urea aqueous system was investigated with 13C NMR, wide X-ray diffraction (WXRD), and solubility test. The two steps were as follows: (1) formation and swelling of a\\u000a cellulose–NaOH complex and (2) dissolution of the cellulose–NaOH complex in aqueous urea solution. The dissolution mechanism\\u000a could be described as strong interaction between

  9. Excimer radiation from Na-Noble-gas and K-Noble-gas molecules

    Microsoft Academic Search

    A. C. Tam; G. Moe; B. R. Bulos; W. Happer

    1976-01-01

    Emission bands from Na-noble-gas (and K-noble-gas) molecules, due to transitions between the 4ssigma (and 5ssigma) bound excited states and dissociating ground states, are observed. The noble gases used are Ar, Kr and Xe. The red shift of the emission band from the forbidden atomic s-s transition is largest for NaXe, for which it is 3055 cm-1. This NaXe band may

  10. Global transcriptome profiling of wild soybean (Glycine soja) roots under NaHCO3 treatment

    Microsoft Academic Search

    Ying Ge; Yong Li; Yan-Ming Zhu; Xi Bai; De-Kang Lv; Dianjing Guo; Wei Ji; Hua Cai

    2010-01-01

    BACKGROUND: Plant roots are the primary site of perception and injury for saline-alkaline stress. The current knowledge of saline-alkaline stress transcriptome is mostly focused on saline (NaCl) stress and only limited information on alkaline (NaHCO3) stress is available. RESULTS: Using Affymetrix® Soybean GeneChip®, we conducted transcriptional profiling on Glycine soja roots subjected to 50 mmol\\/L NaHCO3 treatment. In a total

  11. Membrane-integral pyrophosphatase subfamily capable of translocating both Na+ and H+

    PubMed Central

    Luoto, Heidi H.; Baykov, Alexander A.; Lahti, Reijo; Malinen, Anssi M.

    2013-01-01

    One of the strategies used by organisms to adapt to life under conditions of short energy supply is to use the by-product pyrophosphate to support cation gradients in membranes. Transport reactions are catalyzed by membrane-integral pyrophosphatases (PPases), which are classified into two homologous subfamilies: H+-transporting (found in prokaryotes, protists, and plants) and Na+-transporting (found in prokaryotes). Transport activities have been believed to require specific machinery for each ion, in accordance with the prevailing paradigm in membrane transport. However, experiments using a fluorescent pH probe and 22Na+ measurements in the current study revealed that five bacterial PPases expressed in Escherichia coli have the ability to simultaneously translocate H+ and Na+ into inverted membrane vesicles under physiological conditions. Consistent with data from phylogenetic analyses, our results support the existence of a third, dual-specificity bacterial Na+,H+-PPase subfamily, which apparently evolved from Na+-PPases. Interestingly, genes for Na+,H+-PPase have been found in the major microbes colonizing the human gastrointestinal tract. The Na+,H+-PPases require Na+ for hydrolytic and transport activities and are further activated by K+. Based on ionophore effects, we conclude that the Na+ and H+ transport reactions are electrogenic and do not result from secondary antiport effects. Sequence comparisons further disclosed four Na+,H+-PPase signature residues located outside the ion conductance channel identified earlier in PPases using X-ray crystallography. Our results collectively support the emerging paradigm that both Na+ and H+ can be transported via the same mechanism, with switching between Na+ and H+ specificities requiring only subtle changes in the transporter structure. PMID:23297210

  12. Ion conduction in substates of the batrachotoxin-modified Na+ channel from toad skeletal muscle.

    PubMed Central

    Naranjo, D; Latorre, R

    1993-01-01

    Batrachotoxin-modified Na+ channels from toad muscle were inserted into planar lipid bilayers composed of neutral phospholipids. Single-channel conductances were measured for [Na+] ranging between 0.4 mM and 3 M. When membrane preparations were made in the absence of protease inhibitors, two open conductance states were identified: a fully open state (16.6 pS in 200 mM symmetrical NaCl) and a substate that was 71% of the full conductance. The substate was predominant at [Na+] > 65 mM, whereas the presence of the fully open state was predominant at [Na+] < 15 mM. Addition of protease inhibitors during membrane preparation stabilized the fully open state over the full range of [Na+] studied. In symmetrical Na+ solutions and in biionic conditions, the ratio of amplitudes remained constant and the two open states exhibited the same permeability ratios of PLi/PNa and PCs/PNa. The current-voltage relations for both states showed inward rectification only at [Na+] < 10 mM, suggesting the presence of asymmetric negative charge densities at both channel entrances, with higher charge density in the external side. An energy barrier profile that includes double ion occupancy and asymmetric charge densities at the channel entrances was required to fit the conductance-[Na+] relations and to account for the rectification seen at low [Na+]. Energy barrier profiles differing only in the energy peaks can give account of the differences between both conductance states. Estimation of the surface charge density at the channel entrances is very dependent on the ion occupancy used and the range of [Na+] tested. Independent evidence for the existence of a charged external vestibule was obtained at low external [Na+] by identical reduction of the outward current induced by micromolar additions of Mg2+ and Ba2+. PMID:8388264

  13. Bulk and track etch properties of CR-39 SSNTD etched in NaOH/ethanol

    E-print Network

    Yu, K.N.

    Bulk and track etch properties of CR-39 SSNTD etched in NaOH/ethanol K.F. Chan, F.M.F. Ng, D. described the use of NaOH/ethanol as an etchant for the CR-39 detector, and have determined the corre and track etch properties of CR- 39 in NaOH/ethanol were derived from direct measurements. The bulk etch

  14. Collisional transfer of population and orientation in NaK.

    PubMed

    Wolfe, C M; Ashman, S; Bai, J; Beser, B; Ahmed, E H; Lyyra, A M; Huennekens, J

    2011-05-01

    Collisional satellite lines with |?J| ? 58 have been identified in recent polarization spectroscopy V-type optical-optical double resonance (OODR) excitation spectra of the Rb(2) molecule [H. Salami et al., Phys. Rev. A 80, 022515 (2009)]. Observation of these satellite lines clearly requires a transfer of population from the rotational level directly excited by the pump laser to a neighboring level in a collision of the molecule with an atomic perturber. However to be observed in polarization spectroscopy, the collision must also partially preserve the angular momentum orientation, which is at least somewhat surprising given the extremely large values of ?J that were observed. In the present work, we used the two-step OODR fluorescence and polarization spectroscopy techniques to obtain quantitative information on the transfer of population and orientation in rotationally inelastic collisions of the NaK molecules prepared in the 2(A)(1)?(+)(v' = 16, J' = 30) rovibrational level with argon and potassium perturbers. A rate equation model was used to study the intensities of these satellite lines as a function of argon pressure and heat pipe oven temperature, in order to separate the collisional effects of argon and potassium atoms. Using a fit of this rate equation model to the data, we found that collisions of NaK molecules with potassium atoms are more likely to transfer population and destroy orientation than collisions with argon atoms. Collisions with argon atoms show a strong propensity for population transfer with ?J = even. Conversely, collisions with potassium atoms do not show this ?J = even propensity, but do show a propensity for ?J = positive compared to ?J = negative, for this particular initial state. The density matrix equations of motion have also been solved numerically in order to test the approximations used in the rate equation model and to calculate fluorescence and polarization spectroscopy line shapes. In addition, we have measured rate coefficients for broadening of NaK 3(1)? ? 2(A)(1)?(+)spectral lines due to collisions with argon and potassium atoms. Additional broadening, due to velocity changes occurring in rotationally inelastic collisions, has also been observed. PMID:21548681

  15. Optimization of NaOH Molarity, LUSI Mud/Alkaline Activator, and Na2SiO3/NaOH Ratio to Produce Lightweight Aggregate-Based Geopolymer

    PubMed Central

    Abdul Razak, Rafiza; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Hardjito, Djwantoro; Yahya, Zarina

    2015-01-01

    This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced. PMID:26006238

  16. Ionic conductivity studies and phase analysis of the Na2BeSiO4Na2BeSi2O6 system

    Microsoft Academic Search

    Sten Frostäng; Jêkabs Grîns; Mats Nygren

    1988-01-01

    Compositions along the Na2BeSiO4-Na2BeSi2O6 join in the Na2O-BeO-SiO2 system were prepared by solid state reaction and investigated by means of X-ray powder diffraction and ionic conductivity measurements. Phase stabilities were studied by investigation of quenched samples from 975 to 1335 K. Two phases were observed: an orthorhombic solid solution phase, NaxBex\\/2Si2-x\\/2O4, e.g., 1.80 <= x <= 2.00, apparently isotypic with

  17. Jpi of the Ex=4.52 MeV state in 22Na via the 12C(12C, dgamma)22Na reaction

    Microsoft Academic Search

    A. H. Lumpkin; G. J. Kekelis; K. W. Kemper; J. D. Fox

    1977-01-01

    The enhanced population of the 4.522 MeV state in 22Na at Ec.m.=19.4 MeV in the 12C(12C, d)22Na reaction is confirmed with the particle-gamma coincidence technique. Deuteron-gamma angular correlation results, lifetime measurements, and transmission coefficient calculations combine to allow only a Jpi(4.522)=7+ assignment. NUCLEAR REACTIONS 12C(12C, dgamma), Ec.m.=19.41 MeV; measured Ed, Egamma, d-gamma coincidence; 22Na, Jpi for state at 4.522 MeV.

  18. Ab initio Hartree-Fock Born effective charges of LiH, LiF, LiCl, NaF, and NaCl

    NASA Astrophysics Data System (ADS)

    Shukla, Alok

    2000-05-01

    We use the Berry-phase-based theory of macroscopic polarization of dielectric crystals formulated in terms of Wannier functions, and state-of-the-art Gaussian basis functions, to obtain benchmark ab initio Hartree-Fock values of the Born effective charges of ionic compounds LiH, LiF, LiCl, NaF, and NaCl. We find excellent agreement with the experimental values for all the compounds except LiCl and NaCl, for which the disagreement with the experiments is close to 10% and 16%, respectively. This may imply the importance of many-body effects in those systems.

  19. On the electronic and geometric structure of bimetallic clusters. A comparison of the novel cluster Na 6Pb to Na 6Mg

    Microsoft Academic Search

    Katrin Albert; Konstantin M. Neyman; Vladimir A. Nasluzov; Sergey Ph. Ruzankin; Chahan Yeretzian; Notker Rösch

    1995-01-01

    Density functional studies of the abundant cluster Na6Pb and of its analogue Na6Mg are reported. The structure of Na6Pb has been optimized for a series of symmetry constraints (Oh, D3d, D3h, C5v, C3v and C2v). The resulting binding energies fall within a narrow range of less than 0.1 eV whereas a spread of more than 0.5 eV is calculated for

  20. Growth morphology and electronic structure of Na films on Si(111)-(7×7) and Si(111)-Na(3×1)

    NASA Astrophysics Data System (ADS)

    Paggel, J. J.; Neuhold, G.; Haak, H.; Horn, K.

    1998-09-01

    The growth of thin Na films on the clean Si(111)-(7×7) and the Si(111)-Na(3×1) reconstructions is investigated using scanning tunnelling microscopy as well as core and valence level photoemission. The growth morphology as well as the evolving electronic structure of the overlayer on these different substrates is studied in detail. It is shown that the Na layer on both surface reconstructions is metallic at saturation coverage, but the presence of a distinct interfacial layer in a non-metallic state is demonstrated.

  1. Osmolality- and Na + -dependent effects of hyperosmotic NaCl solution on contractile activity and Ca 2+ cycling in rat ventricular myocytes

    Microsoft Academic Search

    Rafael A. Ricardo; Rosana A. Bassani; José W. M. Bassani

    2008-01-01

    Hypertonic NaCl solutions have been used for small-volume resuscitation from hypovolemic shock. We sought to identify osmolality-\\u000a and Na+-dependent components of the effects of the hyperosmotic NaCl solution (85 mOsm\\/kg increment) on contraction and cytosolic\\u000a Ca2+ concentration ([Ca2+]i) in isolated rat ventricular myocytes. The biphasic change in contraction and Ca2+ transient amplitude (decrease followed by recovery) was accompanied by qualitatively similar

  2. Keeping It Simple, Transport Mechanism and pH Regulation in Na+/H+ Exchangers*

    PubMed Central

    C?linescu, Octavian; Paulino, Cristina; Kühlbrandt, Werner; Fendler, Klaus

    2014-01-01

    Na+/H+ exchangers are essential for regulation of intracellular proton and sodium concentrations in all living organisms. We examined and experimentally verified a kinetic model for Na+/H+ exchangers, where a single binding site is alternatively occupied by Na+ or one or two H+ ions. The proposed transport mechanism inherently down-regulates Na+/H+ exchangers at extreme pH, preventing excessive cytoplasmic acidification or alkalinization. As an experimental test system we present the first electrophysiological investigation of an electroneutral Na+/H+ exchanger, NhaP1 from Methanocaldococcus jannaschii (MjNhaP1), a close homologue of the medically important eukaryotic NHE Na+/H+ exchangers. The kinetic model describes the experimentally observed substrate dependences of MjNhaP1, and the transport mechanism explains alkaline down-regulation of MjNhaP1. Because this model also accounts for acidic down-regulation of the electrogenic NhaA Na+/H+ exchanger from Escherichia coli (EcNhaA, shown in a previous publication) we conclude that it applies generally to all Na+/H+ exchangers, electrogenic as well as electroneutral, and elegantly explains their pH regulation. Furthermore, the electrophysiological analysis allows insight into the electrostatic structure of the translocation complex in electroneutral and electrogenic Na+/H+ exchangers. PMID:24644283

  3. An Na+-pumping V1V0-ATPase complex in the thermophilic bacterium Clostridium fervidus.

    PubMed Central

    Höner zu Bentrup, K; Ubbink-Kok, T; Lolkema, J S; Konings, W N

    1997-01-01

    Energy transduction in the anaerobic, thermophilic bacterium Clostridium fervidus relies exclusively on Na+ as the coupling ion. The Na+ ion gradient across the membrane is generated by a membrane-bound ATPase (G. Speelmans, B. Poolman, T. Abee, and W. N. Konings, J. Bacteriol. 176:5160-5162, 1994). The Na+-ATPase complex was purified to homogeneity. It migrates as a single band in native polyacrylamide gel electrophoresis and catalyzes Na+-stimulated ATPase activity. Denaturing gel electrophoresis showed that the complex consists of at least six different polypeptides with apparent molecular sizes of 66, 61, 51, 37, 26, and 17 kDa. The N-terminal sequences of the 66- and 51-kDa subunits were found to be significantly homologous to subunits A and B, respectively, of the Na+-translocating V-type ATPase of Enterococcus hirae. The purified V1V0 protein complex was reconstituted in a mixture of Escherichia coli phosphatidylethanolamine and egg yolk phosphatidylcholine and shown to catalyze the uptake of Na+ ions upon hydrolysis of ATP. Na+ transport was completely abolished by monensin, whereas valinomycin stimulated the uptake rate. This is indicative of electrogenic sodium transport. The presence of the protonophore SF6847 had no significant effect on the uptake, indicating that Na+ translocation is a primary event and in the cell is not accomplished by an H+-translocating pump in combination with an Na+-H+ antiporter. PMID:9023212

  4. The non-steroidal anti-inflammatory drug, diclofenac, inhibits Na(+) current in rat myoblasts.

    PubMed

    Fei, Xiao-Wei; Liu, Lin-Yun; Xu, Jian-Guang; Zhang, Zhi-Hong; Mei, Yan-Ai

    2006-08-11

    The inhibitory effect of diclofenac, a non-steroidal anti-inflammatory drug (NSAID), on the voltage-gated inward Na+ current (I(Na)) in cultured rat myoblasts was investigated using the whole-cell voltage-clamp technique. At concentrations of 10 nM-100 microM, diclofenac produced a dose-dependent and reversible inhibition of I(Na) with an IC50 of 8.51 microM, without modulating the fast activation and inactivation process. The inhibitory effect of diclofenac took place at resting channels and increased with more depolarizing holding potential. In addition to inhibiting the Na+ current amplitude, diclofenac significantly modulated the steady-state inactivation properties of the Na+ channels, but did not alter the steady-state activation. The steady-state inactivation curve was significantly shifted towards the hyperpolarizing potential in the presence of diclofenac. Furthermore, diclofenac treatment resulted in a fairly slow recovery from inactivation of the Na+ channel. The inhibitory effect of diclofenac was enhanced by repetitive pulses and was inflected by changing frequency; the blocking effect at higher frequency was significantly greater than at lower frequency. Both intracellular and extracellular application of diclofenac could inhibit I(Na), indicating that diclofenac may exert its channel inhibitory action both inside and outside the channel sites. Our data directly demonstrate that diclofenac can inhibit the inward Na+ channels in rat myoblasts. Some different inhibitory mechanisms from that in neuronal Na+ channels are discussed. PMID:16806078

  5. Partial purification and characterization of (Na+ + K+)-ATPase from garfish olfactory nerve axon plasma membrane.

    PubMed

    Kracke, G R; O'Neal, S G; Chacko, G K

    1981-01-01

    The (Na+ + K+)-ATPase of garfish olfactory nerve axon plasma membrane was purified about sixfold by treatment of the membrane with sodium dodecyl sulfate followed by sucrose density gradient centrifugation. The estimated molecular weights of the two major polypeptide components of the enzyme preparation on sodium dodecyl sulfate gels were 110,000 and 42,000 daltons, which were different from those of the corresponding peptides of rabbit kidney (Na+ + K+)-ATPase. No carbohydrate was detected in the 42,000-dalton component either by the periodic acid-Schiff reagent or by the more sensitive concanavalin A-peroxidase staining procedure. The molecular properties of the garfish (Na+ + K+)-ATPase, such as the Km for ATP, pH optimum, energies of activation, Na and K ion dependence and vanadium inhibition, were, however, similar to those of the kidney enzyme. The partially purified garfish (Na+ + K+)-ATPase was reconstituted into phospholipid vesicles by a freeze-thaw-sonication procedure. The reconstituted enzyme was found to catalyze a time and ATP dependent 22Na+ transport. The ratio of 22Na+ pumped to ATP hydrolyzed was about 1; under the same reconstitution and assay conditions, eel electroplax (Na+ + K+)-ATPase, however, gave a 22Na+ pumped to ATP hydrolyzed ratio of nearly 3. PMID:6273569

  6. Multiple quantum filtered 23Na NMR spectroscopy of the isolated, perfused rat liver.

    PubMed

    Colet, J M; Bansal, N; Malloy, C R; Sherry, A D

    1999-06-01

    Isolated, perfused rat livers were examined by single-quantum (SQ) and double-quantum-filtered (DQ-filtered) 23Na spectroscopy during prolonged global ischemia and during perfusion with ouabain, low-buffer potassium, or lithium-enriched buffer. Baseline separation of the intracellular (Na(i)+) and extracellular (Na(e)+) sodium resonances using TmDOTP5- allowed a direct comparison of temporal changes in SQ versus DQ-filtered Na(i)+. The SQ Na(i)+ signal increased approximately 150% during the first 15 min of global ischemia and then remained relatively constant over the next 45 min, while the DQ-filtered signal steadily increased approximately 400% over the same 60 min period. In similar experiments in which all perfusate sodium was replaced by lithium, the DQ-filtered Na(i)+ signal increased approximately 180% over a similar period of ischemia. Exposure of livers to ouabain also resulted in larger increases in DQ-filtered versus SQ signal of Na(i)+. The approximately 290% increase in DQ-filtered sodium observed during perfusion of livers with a hypokalemic buffer (1.2 mM K+) could be completely reversed by continued perfusion with a buffer containing normal levels of K+ (4.7 mM). These data suggest that the DQ-filtered Na(i)+ signal of liver does not simply report an increase in [Na(i)+], but may be exquisitely sensitive to other intracellular events initiated by altered physiology. PMID:10371444

  7. Low temperature transport properties and heat capacity of single-crystal Na8Si46.

    PubMed

    Stefanoski, S; Martin, J; Nolas, G S

    2010-12-01

    The low temperature thermal conductivity, resistivity, and Seebeck coefficient of single-crystal Na(8)Si(46) are investigated revealing the intrinsic low temperature transport properties of this material. Metallic conduction is observed, with a higher residual resistance ratio than any other known type I clathrate. Heat capacity together with thermal conductivity provide insight into the Na disorder inside the polyhedra formed by the Si framework. Single-crystal structural refinement and thermal property analyses reveal anisotropic disorder for Na inside the tetrakaidecahedra due to a reduction in the symmetry inside these polyhedra, unlike that for Na inside the dodecahedra. PMID:21406746

  8. Na(x)-deficient mice show normal vasopressin response to dehydration.

    PubMed

    Nagakura, Ayano; Hiyama, Takeshi Y; Noda, Masaharu

    2010-03-26

    In dehydrated animals, the antidiuretic hormone vasopressin (VP) is released from the nerve terminals of magnocellular neurons of the supraoptic nucleus (SON) and paraventricular nucleus (PVN) into the systemic circulation at the posterior pituitary. Increases in sodium (Na+)-level and osmolality in body fluids upon dehydration are reportedly sensed by a Na+-sensor and/or an osmosensor, respectively. However, it is still unknown whether both are involved in the regulation of production and/or release of VP. Na(x) is the cerebral Na+-level sensor and Na(x)-knockout mice do not stop ingesting salt even when dehydrated. Here we examined VP production/release in Na(x)-knockout mice, and found that they are normal in the VP response to dehydration or intraperitoneal-administration with hypertonic saline. In situ hybridization using an intron-specific probe showed that VP gene expression in the SON did not differ from wild-type mice when dehydrated. Also, there was no significant difference in the activity of subfornical organ neurons projecting to the SON between the two genotypes when stimulated by water deprivation. Furthermore, Na(x)-knockout mice showed a normal response in urine excretion to dehydration. All these results indicate that the information of Na+-level increase detected by Na(x) does not contribute to the control of VP production/release. PMID:20138121

  9. Association with ?-COP Regulates the Trafficking of the Newly Synthesized Na,K-ATPase*

    PubMed Central

    Morton, Michael J.; Farr, Glen A.; Hull, Michael; Capendeguy, Oihana; Horisberger, Jean-Daniel; Caplan, Michael J.

    2010-01-01

    Plasma membrane expression of the Na,K-ATPase requires assembly of its ?- and ?-subunits. Using a novel labeling technique to identify Na,K-ATPase partner proteins, we detected an interaction between the Na,K-ATPase ?-subunit and the coat protein, ?-COP, a component of the COP-I complex. When expressed in the absence of the Na,K-ATPase ?-subunit, the Na,K-ATPase ?-subunit interacts with ?-COP, is retained in the endoplasmic reticulum, and is targeted for degradation. In the presence of the Na,K-ATPase ?-subunit, the ?-subunit does not interact with ?-COP and traffics to the plasma membrane. Pulse-chase experiments demonstrate that in cells expressing both the Na,K-ATPase ?- and ?-subunits, newly synthesized ?-subunit associates with ?-COP immediately after its synthesis but that this interaction does not constitute an obligate intermediate in the assembly of the ?- and ?-subunits to form the pump holoenzyme. The interaction with ?-COP was reduced by mutating a dibasic motif at Lys54 in the Na,K-ATPase ?-subunit. This mutant ?-subunit is not retained in the endoplasmic reticulum and reaches the plasma membrane, even in the absence of Na,K-ATPase ?-subunit expression. Although the Lys54 ?-subunit reaches the cell surface without need for ?-subunit assembly, it is only functional as an ion-transporting ATPase in the presence of the ?-subunit. PMID:20801885

  10. First-principles study on structure stabilities of ?-S and Na-S battery systems

    NASA Astrophysics Data System (ADS)

    Momida, Hiroyoshi; Oguchi, Tamio

    2014-03-01

    To understand microscopic mechanisms of charge and discharge reactions in Na-S batteries, there has been increasing needs to study fundamental atomic and electronic structures of elemental S as well as that of Na-S phases. The most stable form of S is known to be an orthorhombic ?-S crystal at ambient temperature and pressure, and ?-S consists of puckered S8 rings which crystallize in space group Fddd . In this study, the crystal structure of ?-S is examined by using first-principles calculations with and without the van der Waals interaction corrections of Grimme's method, and results clearly show that the van der Waals interactions between the S8 rings have crucial roles on cohesion of ?-S. We also study structure stabilities of Na2S, NaS, NaS2, and Na2S5 phases with reported crystal structures. Using calculated total energies of the crystal structure models, we estimate discharge voltages assuming discharge reactions from 2Na+ xS -->Na2Sx, and discharge reactions in Na/S battery systems are discussed by comparing with experimental results. This work was partially supported by Elements Strategy Initiative for Catalysts and Batteries (ESICB) of Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.

  11. CRMP2 Protein SUMOylation Modulates NaV1.7 Channel Trafficking*

    PubMed Central

    Dustrude, Erik T.; Wilson, Sarah M.; Ju, Weina; Xiao, Yucheng; Khanna, Rajesh

    2013-01-01

    Voltage-gated sodium channel (NaV) trafficking is incompletely understood. Post-translational modifications of NaVs and/or auxiliary subunits and protein-protein interactions have been posited as NaV-trafficking mechanisms. Here, we tested if modification of the axonal collapsin response mediator protein 2 (CRMP2) by a small ubiquitin-like modifier (SUMO) could affect NaV trafficking; CRMP2 alters the extent of NaV slow inactivation conferred by the anti-epileptic (R)-lacosamide, implying NaV-CRMP2 functional coupling. Expression of a CRMP2 SUMOylation-incompetent mutant (CRMP2-K374A) in neuronal model catecholamine A differentiated (CAD) cells did not alter lacosamide-induced NaV slow inactivation compared with CAD cells expressing wild type CRMP2. Like wild type CRMP2, CRMP2-K374A expressed robustly in CAD cells. Neurite outgrowth, a canonical CRMP2 function, was moderately reduced by the mutation but was still significantly higher than enhanced GFP-transfected cortical neurons. Notably, huwentoxin-IV-sensitive NaV1.7 currents, which predominate in CAD cells, were significantly reduced in CAD cells expressing CRMP2-K374A. Increasing deSUMOylation with sentrin/SUMO-specific protease SENP1 or SENP2 in wild type CRMP2-expressing CAD cells decreased NaV1.7 currents. Consistent with a reduction in current density, biotinylation revealed a significant reduction in surface NaV1.7 levels in CAD cells expressing CRMP2-K374A; surface NaV1.7 expression was also decreased by SENP1 + SENP2 overexpression. Currents in HEK293 cells stably expressing NaV1.7 were reduced by CRMP2-K374A in a manner dependent on the E2-conjugating enzyme Ubc9. No decrement in current density was observed in HEK293 cells co-expressing CRMP2-K374A and NaV1.1 or NaV1.3. Diminution of sodium currents, largely NaV1.7, was recapitulated in sensory neurons expressing CRMP2-K374A. Our study elucidates a novel regulatory mechanism that utilizes CRMP2 SUMOylation to choreograph NaV1.7 trafficking. PMID:23836888

  12. Origin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: Grain boundary weakening

    SciTech Connect

    Lu Guanghong [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Zhang Ying; Deng Shenghua; Wang Tianmin [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Kohyama, Masanori [Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, Osaka 563-8577 (Japan); Yamamoto, Ryoichi [Institute of Industrial Science, University of Tokyo, Tokyo 153-8505 (Japan); Liu Feng [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Horikawa, Keitaro [Division of Nonlinear Mechanics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Kanno, Motohiro [Department of Materials Engineering, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan)

    2006-06-01

    Using a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we further show that the presence of Na or Ca impurity, which causes intergranular fracture, reduces the ultimate tensile strength when embrittlement occurs. These results suggest that the Na/Ca-induced intergranular embrittlement of an Al alloy originates mainly from the GB weakening due to the Na/Ca segregation.

  13. Involvement of Na,K-pump in SEPYLRFamide-mediated reduction of cholinosensitivity in Helix neurons.

    PubMed

    Pivovarov, Arkady S; Foreman, Richard C; Walker, Robert J

    2007-02-01

    SEPYLRFamide acts as an inhibitory modulator of acetylcholine (ACh) receptors in Helix lucorum neurones. Ouabain, a specific inhibitor of Na,K-pump, (0.1 mM, bath application) decreased the ACh-induced inward current (ACh-current) and increased the leak current. Ouabain decreased the modulatory SEPYLRFamide effect on the ACh-current. There was a correlation between the effects of ouabain on the amplitude of the ACh-current and on the modulatory peptide effect. Ouabain and SEPYLRFamide inhibited the activity of Helix aspersa brain Na,K-ATPase. Activation of Na,K-pump by intracellular injection of 3 M Na acetate or 3 M NaCl reduced the modulatory peptide effect on the ACh-current. An inhibitor of Na/Ca-exchange, benzamil (25 muM, bath application), and an inhibitor of Ca(2+)-pump in the endoplasmic reticulum, thapsigargin (TG, applied intracellularly), both prevented the effect of ouabain on SEPYLRFamide-mediated modulatory effect. Another inhibitor of Ca(2+)-pump in the endoplasmic reticulum, cyclopiazonic acid (applied intracellularly), did not prevent the effect of ouabain on SEPYLRFamide-mediated modulatory effect. These results indicate that Na,K-pump is responsible for the SEPYLRFamide-mediated inhibition of ACh receptors in Helix neurons. Na/Ca-exchange and intracellular Ca(2+) released from internal pools containing TG-sensitive Ca(2+)-pump are involved in the Na,K-pump pathway for the SEPYLRFamide-mediated inhibition of ACh receptors. PMID:17049630

  14. Developmental changes in erythrocyte Na+,K+-ATPase subunit abundance and enzyme activity in neonates

    PubMed Central

    Vasarhelyi, B.; Tulassay, T.; Ver, A.; Dobos, M.; Kocsis, I.; Seri, I.

    2000-01-01

    AIM—To study the relation between erythrocyte Na+,K+-ATPase subunit isoform composition, Na+,K+-ATPase activity, and cation pump function in preterm and term neonates.?DESIGN—Erythrocyte Na+,K+-ATPase subunit isoform abundance, Na+,K+-ATPase activity, and cation pump function were studied in blood samples obtained from 56 preterm neonates of 28-32 weeks gestation (group 1), 58 preterm neonates of 33-36 weeks gestation (group 2), and 122 term neonates (group 3) during the first two postnatal days.?RESULTS—?1 isoform abundance was higher and ?2 isoform abundance was lower in group 1 than in group 3 (p = 0.0002). ?2 and ?1 isoform abundance did not change with maturation and there was no evidence for the presence of the ?3 isoform. Gestational age was inversely related to Na+,K+-ATPase activity (p = 0.0001) and directly related to intracellular Na+ concentration (p = 0.0025).?CONCLUSIONS—Expression of the ?1 and ?2 Na+,K+-ATPase subunit isoforms is developmentally regulated. The increased abundance of ?1 isoforms of immature neonates translates to increased ATPase activity. The lower intracellular Na+ concentration of immature neonates suggests that their erythrocyte Na+,K+-ATPase cation pump function may also be increased.?? PMID:10952709

  15. Experimentally determined partitioning of Rb between richterites and aqueous (Na, K)-chloride solutions

    NASA Astrophysics Data System (ADS)

    Melzer, Stefan; Gottschalk, Matthias; Heinrich, Wilhelm

    The distribution of Rb-Na and Rb-K between richterite and a 2-molal aqueous (Na, K, Rb)-chloride solution has been investigated with hydrothermal experiments at 800?C and 200MPa. Experiments were performed as syntheses in which amphiboles grew in the presence of an excess fluid containing the exchangeable cations Na+-Rb+ or Na+-K+-Rb+. The obtained amphiboles were large enough (up to 20 m in width) for reliable EMP analysis. They were chemically homogeneous and HRTEM investigations showed that they were structurally well ordered. The Rb, Na, K, Ca and Mg concentrations in coexisting fluids were measured by ICP-AES. According to the possible incorporation of Na, K and Rb on the A-site, solid solutions in the ternary Na(NaCa) Mg5[Si8O22/(OH)2] (richterite)-K(NaCa)Mg5[Si8O22/(OH)2] (K-richterite)-Rb(NaCa)Mg5[Si8O22/(OH)2] (Rb-richterite) were expected. However, Rb-rich richterites always had significant amounts of A-site vacancy concentrations (X?amph=?A/(RbA+KA +NaA+?A) of up to 0.42 in the K-free (Na,Rb)-richterites and of up to 0.67 in the (Na, K, Rb)-richterites which corresponds to the same content of tremolite+cummingtonite-component. Amphiboles containing practically only Rb besides vacancies and no Na and/or K on the A-site were also synthesized, however. The Rb-Na and Rb-K exchange coefficients between fluid and richterites are similar. Rubidium always fractionated strongly into the fluid phase. For low Rb-concentrations in richterite (XRbamph<0.1) a linear correlation between XRbfluid and XRbamph exists. In this concentration range, the derived exchange coefficients KD(Rb-K)amph-fluid and KD(Rb-Na)amph-fluid were 0.08 +/- 0.04 and 0.04 +/- 0.02, respectively. These low exchange coefficients show that significant amounts of Rb in amphiboles require a Rb-rich fluid phase. The results indicate that K-Rb fractionation between alkali amphiboles and fluids is significantly different from K-Rb fractionation between alkali feldspar/ phlogopite and fluid, with KDs of about 0.5 and 1.2, respectively. Formation of richterites will drastically alter the K/Rb-ratios of fluids or melts. These results may have important implications for the genetical interpretation of various geological settings, e.g., MARID-type rocks.

  16. Influence of NaA Zeolite Crystal Expansion/Contraction on Zeolite Membrane Separations

    SciTech Connect

    Sorenson, Stephanie G [University of Colorado, Boulder; Payzant, E Andrew [ORNL; Gibbons, Will T [University of Colorado, Boulder; Soydas, Belma [University of Colorado, Boulder; Kita, Hidetoshi [Yamaguchi University, Japan; Noble, Richard D [University of Colorado, Boulder; Falconer, John L. [University of Colorado, Boulder

    2011-01-01

    In-situ powder XRD measurements showed that the NaA zeolite unit cell contracts and expands upon adsorption, and these changes in zeolite crystal size correlate with permeation changes through NaA zeolite membranes. These membranes had high pervaporation selectivities, even though gas permeation was mainly through defects, as indicated by Knudsen selectivities for gases. At 300 K and a thermodynamic activity of 0.03, water contracted the NaA crystals by 0.22 vol%, and this contraction increased the helium flux through two NaA membranes by approximately 80%. Crystal contraction also increased the fluxes of i-butane during vapor permeation and i-propanol (IPA) during pervaporation (~ 0.03 wt% water). At activities above 0.07, water expanded NaA crystals and correspondingly decreased the membrane fluxes of helium, i-butane, and IPA. Similarly, methanol contracted NaA crystals by 0.05 vol% at an activity of 0.02, and this contraction slightly increased the helium and i-butane fluxes through a NaA membrane. Above an activity of 0.06, methanol expanded the crystals, and the fluxes of helium and i-butane through a NaA membrane decreased. The adsorbate-induced changes explain some pervaporation behavior reported by others, and they indicate that crystal expansion and contraction may increase or decrease zeolite NaA membrane selectivity by changing the defect sizes.

  17. Targeting of renal proximal tubule Na,K-ATPase by salt-inducible kinase.

    PubMed

    Taub, Mary; Springate, James E; Cutuli, Facundo

    2010-03-12

    The renal proximal tubule (RPT) is a central locale for Na+ reabsorption, and blood pressure regulation. Na+ reabsorption in the RPT depends upon the Na,K-ATPase, which is controlled by a complex regulatory network, including Salt-Inducible Protein Kinase (SIK). SIKs are recently discovered members of the AMP-activated Protein Kinase (AMPK) family, which regulate salt homeostasis and metabolism in a number of tissues. In the RPT, SIK interacts with the Na,K-ATPase in the basolateral membrane (BM), regulating both the activity and level of Na,K-ATPase in the BM. Thus, Na,K-ATPase activity can be rapidly adjusted in response to changes in Na+ balance. Long-term changes in Na+ intake affect the state of SIK phosphorylation, and as a consequence the phosphorylation of TORCs, Transducers of Regulated CREB (cAMP Regulatory Element Binding Protein). Once phosphorylated, TORCs enter the nucleus, and activate transcription of the ATP1B1 gene encoding for the Na,K-ATPase beta subunit. PMID:20152810

  18. Hadron distributions — Recent results from the CERN experiment NA44

    NASA Astrophysics Data System (ADS)

    Xu, Nu; Bearden, I. G.; Bøggild, H.; Boissevain, J.; Dodd, J.; Erazmus, B.; Esumi, S.; Fabjan, C. W.; Ferenc, D.; Fields, D. E.; Franz, A.; Gaardhøje, J. J.; Hansen, O.; Hardtke, D.; van Hecke, H.; Holzer, E. B.; Humanic, T.; Hummel, P.; Jacak, B. V.; Jayanti, R.; Kaneta, M.; Kopytine, M.; Leltchouk, M.; Ljubicic, T.; Lörstad, B.; Maeda, N.; Medvedev, A.; Murray, M.; Nishimura, S.; Ohnishi, H.; Paic, G.; Pandey, S. U.; Piuz, F.; Pluta, J.; Polychronakos, V.; Potekhin, M.; Poulard, G.; Sakaguchi, A.; Simon-Gillo, J.; Schmidt-Sørensen, J.; Sondheim, W.; Spegel, M.; Sugitate, T.; Sullivan, J. P.; Sumi, Y.; Willis, W. J.; Wolf, K.; Xu, N.; Zachary, D. S.; NA44 Collaboration

    1996-02-01

    Proton distributions at midrapidity have been measured for 158A·GeV Pb+Pb collisions in the focusing spectrometer experiment NA44 at CERN. A high degree of nuclear stopping is found in the truly heavy ion collisions. Systematic results of single particle transverse momentum distributions of pions, kaons, and protons, of 200A·GeV S+S and 158A·GeV Pb+Pb central collisions will be addressed within the context of thermalization. By comparing these data with thermal and transport models, freeze-out parameters such as the temperature parameter Tfo and mean collective flow velocity are extracted. Preliminary results of the particle ratios of {K -}/{K +} and {overlinep}/{p} are discussed in the context of cascade models of RQMD and VENUS.

  19. Two-Photon Cooperative Absorption in Colliding Cold Na Atoms

    NASA Astrophysics Data System (ADS)

    Pedrozo-Peñafiel, E.; Paiva, R. R.; Vivanco, F. J.; Bagnato, V. S.; Farias, K. M.

    2012-06-01

    Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P1/2 and a P3/2 atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.

  20. Crystals of Na(+)/K(+)-ATPase with bound cisplatin.

    PubMed

    Huliciak, Miroslav; Reinhard, Linda; Laursen, Mette; Fedosova, Natalya; Nissen, Poul; Kubala, Martin

    2014-12-01

    Cisplatin is the most widely used chemotherapeutics for cancer treatment, however, its administration is connected to inevitable adverse effects. Previous studies suggested that cisplatin is able to inhibit Na(+)/K(+)-ATPase (NKA), the enzyme responsible for maintaining electrochemical potential and sodium gradient across the plasma membrane. Here we report a crystallographic analysis of cisplatin bound to NKA in the ouabain bound E2P form. Despite a moderate resolution (7.4 Å and 7.9 Å), the anomalous scattering from platinum and a model representation from a recently published structure enabled localization of seven cisplatin binding sites by anomalous difference Fourier maps. Comparison with NKA structures in the E1P conformation suggested two possible inhibitory mechanisms for cisplatin. Binding to Met151 can block the N-terminal pathway for transported cations, while binding to Met171 can hinder the interaction of cytoplasmic domains during the catalytic cycle. PMID:25199459

  1. Electrochemical reactions in a pure Na2SO4 melt

    SciTech Connect

    Fang, W.C.; Rapp, R.A.

    1983-12-01

    Cyclic voltammetry and chronopotentiometry were used to study the electrochemical reduction reactions of SO3 gas O2 and SO4S ions in a Na2SO4 melt at 900C. The reduction reaction of SO3 follows a ce mechanism: SO3 first reacts chemically with SO4S to form S2O7S and then proceeds via a one-electron electrochemical reduction reaction to form SO3 . The reduction of peroxide O2 ions forms either OS or both OS and superoxide O2S ions. Sulfate ions are subjected to decomposition at either very positive or very negative potentials. At very high positive potentials, sulfate ions decompose to evolve SO2 and O2 gases, in addition superoxide ions are also formed. At very negative potentials, sulfate ions decompose to form sulfide and peroxide. 24 references, 11 figures, 2 tables.

  2. Neutron diffraction study of NaNO2 ferroelectric nanowires

    NASA Astrophysics Data System (ADS)

    Borisov, S.; Hansen, T.; Kumzerov, Yu.; Naberezhnov, A.; Simkin, V.; Smirnov, O.; Sotnikov, A.; Tovar, M.; Vakhrushev, S.

    2004-07-01

    For the first time the temperature evolution of the structure of ferroelectric nanowires of NaNO2 was studied by neutron diffraction from room temperature up to melting, i.e. in ferro- and paraelectric phases. Samples were produced in natural chrysotile asbestos with average channel diameter 6+/-1.5nm. It is demonstrated that in the ferroelectric phase the structure is consistent with the bulk but is strongly textured. The temperature dependence of order parameter in the ferroelectric phase is determined for the confined sodium nitrite. It is shown that this dependence follows a power law with Tc=413.0+/-2.5K and ?=0.34+/-0.05, and differs from the same for the bulk material.

  3. Long Life Na/NiCl2 Cells

    NASA Technical Reports Server (NTRS)

    Bugga, Ratnakumar V. (Inventor); Surampudi, Subbarao (Inventor); Halpert, Gerald (Inventor)

    1996-01-01

    The premature capacity failure of Na/NiCl2 secondary cells due to agglomeration of nickel particles on the surface of the NiCl2 cathode is prevented by addition of a minor amount such as 10 percent by weight of a transition metal such as Co, Fe or Mn to the cathode. The chlorides of the transition metals have lower potentials than nickel chloride and chlorinate during charge. A uniform dispersion of the transition metals in the cathodes prevents agglomeration of nickel, maintains morphology of the electrode, maintains the electrochemical area of the electrode and thus maintains capacity of the electrode. The additives do not effect sintering. The addition of sulfur to the liquid catholyte is expected to further reduce agglomeration of nickel in the cathode.

  4. Hadron distributions - recent results from the CERN experiment NA44

    SciTech Connect

    Xu, N.

    1996-09-01

    Proton distributions at midrapidity have been measured for 158A{circ}GeV/c Pb + Pb collisions in the focusing spectrometer experiment NA44 at CERN. A high degree of nuclear stopping is found in the truly heavy ion collisions. Systematic results of single particle transverse momentum distributions of pions, kaons, and protons, of 200A-GeV/c S+S and 158A{circ}GeV/c Pb+Pb central collisions will be addressed within the context of thermalization. By comparing these data with thermal and transport models, freeze-out parameters such as the temperature parameter T{sub fo} and mean collective flow velocity ({Beta}) are extracted. Preliminary results of the particle ratios of K{sup -}/K{sup +} and p/p are discussed in the context of cascade models of RQMD and VENUS.

  5. Experimental Studies of Interacting Electronic States in NaCs

    NASA Astrophysics Data System (ADS)

    Faust, Carl E.

    This dissertation describes methods and results of spectroscopic studies of the NaCs molecule. NaCs is of particular interest in many labs where experimental studies of ultra-cold molecules are being conducted. Data obtained in the present work will also be useful as benchmarks for various theoretical calculations. Our goals in studying this molecule were to map out high lying electronic states and to understand how these states interact with one another. Sodium and cesium metal were heated in a heat-pipe oven to form a vapor of NaCs molecules. These molecules were excited using narrow band, continuous wave (cw), tunable lasers. We employed the optical-optical double resonance (OODR) technique to obtain Doppler-free spectra of transitions to rotational and vibrational levels of high lying electronic states. One state of particular interest was the 12(0+) electronic state. Rovibrational level energies corresponding to this state were measured and used to generate a potential energy curve using computer programs to implement both the Rydberg-Klein-Rees (RKR) method and the inverted perturbation approach (IPA). By observing fluorescence from the 12(0+) state resolved as a function of wavelength, we determined that this state interacts with the nearby 11(0+) electronic state, which was previously mapped out by Ashman et al. A two-stage coupling model was devised to describe the resolved fluorescence originating from these two interacting states. The electronic states interact via spin-orbit coupling, while the individual rovibrational levels interact via a second mechanism, likely nonadiabatic coupling. This two-stage coupling between the levels of these states causes quantum interference between fluorescence pathways associated with different components of the wavefunctions describing these levels. This interference results in more complicated resolved fluorescence spectra. The model was used to fit parameters describing these interactions so that the resolved fluorescence spectra could be reproduced. The NaCs 43pi0+ electronic state was also studied in this work. Energies of many rovibrational levels belonging to the 43pi0+ electronic state were measured. This state is interesting because it likely has a potential energy curve with a double minimum, which results in a different type of quantum interference, directly observed in resolved spectra. The state also very likely has interactions with the 11(0+) and 12(0+) states. Energies of many rovibrational levels lying above the energy of the barrier between the two minima were measured, and it appears that we also observed a few levels lying below the barrier. Since the laser wavelengths necessary to excite the lowest vibrational levels were not available, an experimental potential curve could not be produced. Therefore, rovibrational level energies and spectroscopic constants are tabulated.

  6. Na7Al3(As2O7)4

    PubMed Central

    Fakhar Bourguiba, Noura; Driss, Ahmed

    2013-01-01

    The title compound, hepta­sodium trialuminium tetrakis(diarsenate), has been isolated as single crystals from a solid-state reaction. Its structure, which is isotypic with that of the Na7Fe3(X 2O7)4 (X = As, P) family of compounds, consists of AlO6 octa­hedra sharing their vertices with As2O7 groups, forming a three-dimensional [Al3(As2O7)4]? framework incorporating channels occupied by the sodium ions. One of the aluminium ions lies on a crystallographic twofold axis. The sodium ions are situated over ten positions (one with site symmetry 2), all but one of which are partially occupied. PMID:24109258

  7. Structure and properties of ?-NaFeO{sub 2}-type ternary sodium iridates

    SciTech Connect

    Baroudi, Kristen, E-mail: kbaroudi@princeton.edu [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Yim, Cindi [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Wu, Hui [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Huang, Qingzhen [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Roudebush, John H. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Vavilova, Eugenia [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Zavoisky Physical Technical Institute, Russian Academy of Sciences, Kazan (Russian Federation); Grafe, Hans-Joachim; Kataev, Vladislav [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, Dresden (Germany); Ji, Huiwen [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Kuo, Changyang; Hu, Zhiwei; Pi, Tun-Wen [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Pao, Chiwen; Lee, Jyhfu [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC (China); Mikhailova, Daria; Hao Tjeng, Liu [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Cava, R.J. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States)

    2014-02-15

    The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na{sub 3?x}MIr{sub 2}O{sub 6} and Na{sub 3?x}M{sub 2}IrO{sub 6}, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R?3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient ?-NaFeO{sub 2}-type phases with formulas Na{sub 1?x}M{sub 1/3}Ir{sub 2/3}O{sub 2} or Na{sub 1?x}M{sub 2/3}Ir{sub 1/3}O{sub 2}. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal–iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}, and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} display dominant antiferromagnetic interactions. For Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2} the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. {sup 23}Na nuclear magnetic resonance measurements comparing Na{sub 2}IrO{sub 3} to Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} provide strong indications that the electron spins are short-range ordered in the latter two materials. Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} are spin glasses. (CSD-numbers: Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}: 426657, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}: 426659, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}: 426658, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}: 426656, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}: 426655, and Na{sub 2.8}ZnIr{sub 2}O{sub 6}: 426660.) - Graphical abstract: Diffraction patterns of Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2}: neutron diffraction patterns in the main panel and synchrotron diffraction in the insets. The patterns show a small amount of ordering in the transition metal iridium layer. Display Omitted - Highlights: • We report six ternary sodium iridates with the ?-NaFeO{sub 2} structure. • Compounds Na{sub 1?x}M{sub 1/3}Ir{sub 2/3}O{sub 2}, M=Co, Ni, Cu, Zn and Na{sub 1?x}M{sub 2/3}Ir{sub 1/3}O{sub 2}, M=Mn, Fe. • Rietveld refinement of powder neutron diffraction data. • All compounds are spin glasses. • NMR comparison to Na{sub 2}IrO{sub 3}.

  8. Na+ Channel ? Subunits: Overachievers of the Ion Channel Family

    PubMed Central

    Brackenbury, William J.; Isom, Lori L.

    2011-01-01

    Voltage-gated Na+ channels (VGSCs) in mammals contain a pore-forming ? subunit and one or more ? subunits. There are five mammalian ? subunits in total: ?1, ?1B, ?2, ?3, and ?4, encoded by four genes: SCN1B–SCN4B. With the exception of the SCN1B splice variant, ?1B, the ? subunits are type I topology transmembrane proteins. In contrast, ?1B lacks a transmembrane domain and is a secreted protein. A growing body of work shows that VGSC ? subunits are multifunctional. While they do not form the ion channel pore, ? subunits alter gating, voltage-dependence, and kinetics of VGSC? subunits and thus regulate cellular excitability in vivo. In addition to their roles in channel modulation, ? subunits are members of the immunoglobulin superfamily of cell adhesion molecules and regulate cell adhesion and migration. ? subunits are also substrates for sequential proteolytic cleavage by secretases. An example of the multifunctional nature of ? subunits is ?1, encoded by SCN1B, that plays a critical role in neuronal migration and pathfinding during brain development, and whose function is dependent on Na+ current and ?-secretase activity. Functional deletion of SCN1B results in Dravet Syndrome, a severe and intractable pediatric epileptic encephalopathy. ? subunits are emerging as key players in a wide variety of physiopathologies, including epilepsy, cardiac arrhythmia, multiple sclerosis, Huntington’s disease, neuropsychiatric disorders, neuropathic and inflammatory pain, and cancer. ? subunits mediate multiple signaling pathways on different timescales, regulating electrical excitability, adhesion, migration, pathfinding, and transcription. Importantly, some ? subunit functions may operate independently of ? subunits. Thus, ? subunits perform critical roles during development and disease. As such, they may prove useful in disease diagnosis and therapy. PMID:22007171

  9. PLASMODIUM FALCIPARUM Na+/H+ EXCHANGER ACTIVITY AND QUININE RESISTANCE +

    PubMed Central

    Bennett, Tyler N.; Patel, Jigar; Ferdig, Michael T.; Roepe, Paul D.

    2009-01-01

    Mutations in the Plasmodium falciparum pfcrt gene cause resistance to the 4 – amino quinoline chloroquine (CQ) and other antimalarial drugs. Mutations and/or overexpression of a P. falciparum multidrug resistance gene homologue (pfmdr1) may further modify or tailor the degree of quinoline drug resistance. Recently (M.T. Ferdig et al., Molecular Microbiology 52: 985–997 [2004]) QTL analysis further implicated a region of P. falciparum chromosome 13 as a partner (with pfcrt) in conferring resistance to the first quinoline – based antimalarial drug, quinine (QN). Since QN resistance (QNR) and CQR are often (but not always) observed together in parasite strains, since elevated cytosolic pH is frequently (but not always) found in CQR parasites, and since the chr 13 segment linked to QNR prominently harbors a gene encoding what appears to be a P. falciparum Na+/H+ exchanger (PfNHE), we have systematically measured cytosolic pH and PfNHE activity for an extended series of parasite strains used in the QTL analysis. Altered PfNHE activity does not correlate with CQR as previously proposed, but significantly elevated PfNHE activity is found for strains with high levels of QNR, regardless their CQR status. We propose that either an elevated pHcyt or a higher vacuolar pH – to – cytosolic pH gradient contributes to one common route to malarial QNR that is also characterized by recently defined chr 13 – chr 9 pairwise interactions. Based on sequence analysis we propose a model whereby observed polymorphisms in PfNHE may lead to altered Na+/H+ set point regulation in QNR parasites. PMID:17353059

  10. Basolateral Na+/HCO3– cotransport activity is regulated by the dissociable Na+/H+ exchanger regulatory factor

    PubMed Central

    Bernardo, Angelito A.; Kear, Felicidad T.; Santos, Anna V.P.; Ma, Jianfei; Steplock, Debra; Robey, R. Brooks; Weinman, Edward J.

    1999-01-01

    In the renal proximal tubule, the activities of the basolateral Na+/HCO3– cotransporter (NBC) and the apical Na+/H+ exchanger (NHE3) uniformly vary in parallel, suggesting that they are coordinately regulated. PKA-mediated inhibition of NHE3 is mediated by a PDZ motif–containing protein, the Na+/H+ exchanger regulatory factor (NHE-RF). Given the common inhibition of these transporters after protein kinase A (PKA) activation, we sought to determine whether NHE-RF also plays a role in PKA-regulated NBC activity. Renal cortex immunoblot analysis using anti-peptide antibodies directed against rabbit NHE-RF demonstrated the presence of this regulatory factor in both brush-border membranes (BBMs) and basolateral membranes (BLMs). Using a reconstitution assay, we found that limited trypsin digestion of detergent solubilized rabbit renal BLM preparations resulted in NBC activity that was unaffected by PKA activation. Co-reconstitution of these trypsinized preparations with a recombinant protein corresponding to wild-type rabbit NHE-RF restored the inhibitory effect of PKA on NBC activity in a concentration-dependent manner. NBC activity was inhibited 60% by 10–8M NHE-RF; this effect was not observed in the absence of PKA. Reconstitution with heat-denatured NHE-RF also failed to attenuate NBC activity. To establish further a physiologic role for NHE-RF in NBC regulation, the renal epithelial cell line B-SC-1, which lacks detectable endogenous NHE-RF expression, was engineered to express stably an NHE-RF transgene. NHE-RF–expressing B-SC-1 cells (B-SC-RF) exhibited markedly lower basal levels of NBC activity than did wild-type controls. Inhibition of NBC activity in B-SC-RF cells was enhanced after 10 ?M of forskolin treatment, consistent with a postulated role for NHE-RF in mediating the inhibition of NBC activity by PKA. These findings not only suggest NHE-RF involvement in PKA-regulated NBC activity, but also provide a unique molecular mechanism whereby basolateral NBC and apical NHE3 activities may be coordinately regulated in renal proximal tubule cells. J. Clin. Invest. 104:195–201 (1999). PMID:10411549

  11. Interstellar Lines NaI 5890 (D2), NaI 5896 (D1) in the Spectra of the Wolf-Rayet Type Star HD 192163

    NASA Astrophysics Data System (ADS)

    Rustamov, J. N.; Abdulkerimova, A. F.

    2012-08-01

    Results of spectral investigations of the interstellar absorption lines NaI 5890 (D2) and NaI 5896 (D1) in a spectrum of a Wolf-Rayet type star HD 192163 are presented. Observations carried out at Cassegrain focus of 2- meter "Zeiss-2000" telescope of N.Tusi Shamakhy Astrophysical observatory (ShAO) of NAS Azerbaijan in 2005-2010. 46 eshelle-spectrograms of star HD 192163, and also 4 eshelle-spectrograms of star HD 191765 and standard star HD 18947 for the purpose of comparative research of lines of doublet NaI 5890 (D2) and NaI 5896 (D1) were investigated. The asymmetry of profiles of these interstellar absorption lines had been revealed only in the spectra of HD 192163 and this asymmetry is interpreted by the contribution of genetic associated with the star HD 192163 ring nebula NGC 6888, in formation of these lines.

  12. Study of intradrystalline diffusion in zeolites communication 3. Kinetics of adsorption of trans-2-butene by NaA and NaMgA zeolites

    SciTech Connect

    Broddak, R.; Dubinin, M.M.; Falko, L.A.; Gorlov, V.A.; Kuhlmann, B.; Scholner, E.; Voloshchuk, A.M.

    1985-09-10

    This article studies the kinetics of adsorption of trans-2-butene by NaA zeolite with a varying crystal size, microcrystalline granulated NaA zeolite using granules of different sizes, and microcrystalline powdered Na/sub 8/Mg/sub 2/A zeolite. It is shown that the rate of adsorption is determined by the intracrystalline diffusion and that the effect of transfer in the transport pores and the final rate of dissipation of the heat of adsorption can be neglected. In adsorption of trans-2-butene by Na/sub 8/Mg/sub 2/A zeolite with a stepwise change in the pressure of the adsorbate, the kinetic curves are satisfactorily described by an internal diffusion equation for the kinetics of isothermal adsorption. The kinetics of adsorption were studied at 303 degrees K from the one-component vapor phase on a vacuum adsorption setup using quartz spring balance.

  13. Calculations of nonlinear optical responses of isomorphous crystals NaClO 3 and NaBrO 3 with natural optical activity

    NASA Astrophysics Data System (ADS)

    Xue, Dongfeng; Zhang, Siyuan

    1998-05-01

    This work considers the isomorphous optically active crystals NaClO 3 and NaBrO 3. The connection between their second-order nonlinear optical (NLO) responses and chemical bond structures is established, starting from the experimental optical activities. The calculation reproduces the well-known experimental fact that crystals of NaClO 3 and NaBrO 3 with similar structures have different signs of optical rotation and of second harmonic generation (SHG). Unlike previous bond charge models, the method may include more than one type of bond in the calculation, and therefore may be used to study the optical activity and nonlinear optical properties of more general crystals.

  14. Oxygen nonstoichiometry and the origin of Na ion ordering in P2-Na[subscript x]CoO[subscript 2

    E-print Network

    Lee, Patrick A.

    The impact of oxygen deficiency on physical properties of Na[subscript 2/3]CoO[subscript 2?delta] has been investigated. From the combined thermogravimetric, magnetic susceptibility, and synchrotron x-ray Laue diffraction ...

  15. Skin sodium measured with ²³Na MRI at 7.0 T.

    PubMed

    Linz, Peter; Santoro, Davide; Renz, Wolfgang; Rieger, Jan; Ruehle, Anjuli; Ruff, Jan; Deimling, Michael; Rakova, Natalia; Muller, Dominik N; Luft, Friedrich C; Titze, Jens; Niendorf, Thoralf

    2015-01-01

    Skin sodium (Na(+) ) storage, as a physiologically important regulatory mechanism for blood pressure, volume regulation and, indeed, survival, has recently been rediscovered. This has prompted the development of MRI methods to assess Na(+) storage in humans ((23) Na MRI) at 3.0 T. This work examines the feasibility of high in-plane spatial resolution (23) Na MRI in skin at 7.0 T. A two-channel transceiver radiofrequency (RF) coil array tailored for skin MRI at 7.0 T (f = 78.5 MHz) is proposed. Specific absorption rate (SAR) simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Human skin was examined in an in vivo feasibility study using two-dimensional gradient echo imaging. Normal male adult volunteers (n = 17; mean ± standard deviation, 46 ± 18 years; range, 20-79 years) were investigated. Transverse slices of the calf were imaged with (23) Na MRI using a high in-plane resolution of 0.9 × 0.9 mm(2) . Skin Na(+) content was determined using external agarose standards covering a physiological range of Na(+) concentrations. To assess the intra-subject reproducibility, each volunteer was examined three to five times with each session including a 5-min walk and repositioning/preparation of the subject. The age dependence of skin Na(+) content was investigated. The (23) Na RF coil provides improved sensitivity within a range of 1 cm from its surface versus a volume RF coil which facilitates high in-plane spatial resolution imaging of human skin. Intra-subject variability of human skin Na(+) content in the volunteer population was <10.3%. An age-dependent increase in skin Na(+) content was observed (r = 0.78). The assignment of Na(+) stores with (23) Na MRI techniques could be improved at 7.0 T compared with current 3.0?T technology. The benefits of such improvements may have the potential to aid basic research and clinical applications designed to unlock questions regarding the Na(+) balance and Na(+) storage function of skin. PMID:25328128

  16. Regulation of Na-Cl absorption in rabbit proximal colon in vitro

    SciTech Connect

    Sellin, J.H.; De Siognie, R.

    1987-01-01

    Ion transport in rabbit proximal colon (PC) in vitro is dominated by a Na-Cl cotransport system stimulated by epinephrine. To further characterize the regulation of Na-Cl transport, the authors tested the effects of specific adrenergic agonists on ion fluxes under short-circuit conditions. Additionally, they tested the effects of the transport inhibitors bumetanide, furosemide, and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS). Basal Na and Cl absorption were essentially nil. The ..cap alpha../sub 2/-agonist clonidine significantly increased net Na and Cl absorption. The ..cap alpha../sub 1/-agonist phenylephrine and the ..beta..-agonist isoproterenol did not alter ion transport. The ..cap alpha../sub 2/-blocker yohimbine (YOH) had a complex, concentration-dependent effect. Propranolol (10/sup -5/ M) and pracozin (10/sup -6/ M) did not significantly alter either basal or stimulated ion transport. Neither bumetanide (10/sup -6/ or 10/sup -4/ M) nor furosemide (10/sup -4/ M) blocked epinephrine-stimulated Na absorption. SITS (10/sup -4/ M) and removal of mucosal K did not have a significant effect on ion transport. Conclusions: 1) Na-Cl cotransport in rabbit PC is primarily under ..cap alpha../sub 2/-adrenergic control, 2) YOH at high concentrations acts as an agonist in PC, 3) ..cap alpha../sub 2/-adrenergic agonists stimulate Na-Cl absorption in both rabbit ileum and PC. In PC, however, the process is electrically quiet and therefore does not appear to be associated with electrogenic HCO/sub 3/ secretion as found in ileum, 4) the lack of effect of bumetanide, furosemide, and 0 K on Na transport suggests that a single Na-Cl (or Na-K-2Cl) carrier is not involved in Na-Cl cotransport in proximal colon.

  17. The reactions of Na{sub 2} with O{sub 2}

    SciTech Connect

    Hou, H.; Lu, K.T.; Sadchenko, V.; Suits, A.G.; Lee, Y.T. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

    1995-09-01

    The reactions of Na{sub 2} with O{sub 2} were studied in a crossed-beam experiment at collision energies (E{sub c}) of 8 and 23 kcal/mol. The formation of NaO{sub 2} + Na was observed at both collision energies, with the angular distributions of NaO{sub 2} in the center of mass coordinates peaking strongly forward with respect to the direction of the O{sub 2} beam, suggesting that the reaction is completed in a time scale that is shorter than one rotational period of the molecular system. From the velocity distribution of the products, the authors found that the newly formed NaO{sub 2} molecules are internally excited, with less than 20% of the available energy appearing in the translational motion of the separating products. These results indicate a ``spectator stripping`` mechanism for the reaction, with the O{sub 2} stripping one Na off the Na{sub 2} molecules. At E{sub c} = 23 kcal/mol the cross section for this reaction channel is estimated to be 0.8 {angstrom}{sup 2}. Another reaction channel which produces NaO + NaO was seen at E{sub c} = 23 kcal/mol. The angular distribution for NaO is broad and forward-backward symmetric in the center of mass frame. A substantial fraction of the available energy is released into the relative motion of the products. This reaction is likely to proceed on an excited potential energy surface since a charge transfer to the excited O{sub 2}{sup {minus}} orbitals seems necessary for breaking the O-O bond. The measurement yields a bond energy of 60 kcal/mol for the Na-O molecule, and a total cross section of 2 {angstrom}{sup 2} for this reaction channel at E{sub c} = 23 kcal/mol.

  18. Identification of the Intracellular Na+ Sensor in Slo2.1 Potassium Channels.

    PubMed

    Thomson, Steven J; Hansen, Angela; Sanguinetti, Michael C

    2015-06-01

    Slo2 potassium channels have a very low open probability under normal physiological conditions, but are readily activated in response to an elevated [Na(+)]i (e.g. during ischemia). An intracellular Na(+) coordination motif (DX(R/K)XXH) was previously identified in Kir3.2, Kir3.4, Kir5.1, and Slo2.2 channel subunits. Based loosely on this sequence, we identified five potential Na(+) coordination motifs in the C terminus of the Slo2.1 subunit. The Asp residue in each sequence was substituted with Arg, and single mutant channels were heterologously expressed in Xenopus oocytes. The Na(+) sensitivity of each of the mutant channels was assessed by voltage clamp of oocytes using micropipettes filled with 2 m NaCl. Wild-type channels and four of the mutant Slo2.1 channels were rapidly activated by leakage of NaCl solution into the cytoplasm. D757R Slo2.1 channels were not activated by NaCl, but were activated by the fenamate niflumic acid, confirming their functional expression. In whole cell voltage clamp recordings of HEK293 cells, wild-type but not D757R Slo2.1 channels were activated by a [NaCl]i of 70 mm. Thus, a single Asp residue can account for the sensitivity of Slo2.1 channels to intracellular Na(+). In excised inside-out macropatches of HEK293 cells, activation of wild-type Slo2.1 currents by 3 mm niflumic acid was 14-fold greater than activation achieved by increasing [NaCl]i from 3 to 100 mm. Thus, relative to fenamates, intracellular Na(+) is a poor activator of Slo2.1. PMID:25903137

  19. Effects of ?-irradiation on Na,K-ATPase in cardiac sarcolemma.

    PubMed

    Mézešová, L; Vlkovi?ová, J; Kalo?ayová, B; Jendruchová, V; Baran?ík, M; Fülöp, M; Slezák, J; Babál, P; Janega, P; Vrbjar, N

    2014-03-01

    Previous studies showed that adverse effect of ionizing radiation on the cardiovascular system is beside other factors mostly mediated by reactive oxygen and nitrogen species, which deplete antioxidant stores. One of the structures highly sensitive to radicals is the Na,K-ATPase the main system responsible for extrusion of superfluous Na(+) out of the cell which utilizes the energy derived from ATP. The aim of present study was the investigation of functional properties of cardiac Na,K-ATPase in 20-week-old male rats 6 weeks after ?-irradiation by a dose 25 Gy (IR). Irradiation induced decrease of systolic blood pressure from 133 in controls to 85 mmHg in IR group together with hypertrophy of right ventricle (RV) and hypotrophy of left ventricle (LV). When activating the cardiac Na,K-ATPase with substrate, its activity was lower in IR in the whole concentration range of ATP. Evaluation of kinetic parameters revealed a decrease of the maximum velocity (V max) by 40 % with no changes in the value of Michaelis-Menten constant (K m). During activation with Na(+), we observed a decrease of the enzyme activity in hearts from IR at all tested Na(+) concentrations. The value of V max decreased by 38 %, and the concentration of Na(+) that gives half maximal reaction velocity (K Na) increased by 62 %. This impairment in the affinity of the Na(+)-binding site together with decreased number of active Na,K-ATPase molecules, as indicated by lowered V max values, are probably responsible for the deteriorated efflux of the excessive Na(+) from the intracellular space in hearts of irradiated rats. PMID:24347175

  20. Sodium flux ratio in Na/K pump-channels opened by palytoxin.

    PubMed

    Rakowski, R F; Artigas, Pablo; Palma, Francisco; Holmgren, Miguel; De Weer, Paul; Gadsby, David C

    2007-07-01

    Palytoxin binds to Na(+)/K(+) pumps in the plasma membrane of animal cells and opens an electrodiffusive cation pathway through the pumps. We investigated properties of the palytoxin-opened channels by recording macroscopic and microscopic currents in cell bodies of neurons from the giant fiber lobe, and by simultaneously measuring net current and (22)Na(+) efflux in voltage-clamped, internally dialyzed giant axons of the squid Loligo pealei. The conductance of single palytoxin-bound "pump-channels" in outside-out patches was approximately 7 pS in symmetrical 500 mM [Na(+)], comparable to findings in other cells. In these high-[Na(+)], K(+)-free solutions, with 5 mM cytoplasmic [ATP], the K(0.5) for palytoxin action was approximately 70 pM. The pump-channels were approximately 40-50 times less permeable to N-methyl-d-glucamine (NMG(+)) than to Na(+). The reversal potential of palytoxin-elicited current under biionic conditions, with the same concentration of a different permeant cation on each side of the membrane, was independent of the concentration of those ions over the range 55-550 mM. In giant axons, the Ussing flux ratio exponent (n') for Na(+) movements through palytoxin-bound pump-channels, over a 100-400 mM range of external [Na(+)] and 0 to -40 mV range of membrane potentials, averaged 1.05 +/- 0.02 (n = 28). These findings are consistent with occupancy of palytoxin-bound Na(+)/K(+) pump-channels either by a single Na(+) ion or by two Na(+) ions as might be anticipated from other work; idiosyncratic constraints are needed if the two Na(+) ions occupy a single-file pore, but not if they occupy side-by-side binding sites, as observed in related structures, and if only one of the sites is readily accessible from both sides of the membrane. PMID:17562821