Sample records for na agua para

  1. HOJA INFORMATIVA Presencia de PFOA y PFOS en el agua potable Avisos de salud

    EPA Pesticide Factsheets

    La EPA estableció avisos de salud sobre el ácido perfluorooctanoico (PFOA) y el sulfonato de perfluorooctano (PFOS) para proporcionar información a los operadores de sistemas de agua potable y funcionarios estatales y locales para que puedan adoptar las me

  2. Avisos de salud sobre el PFOA y PFOS en el agua potable

    EPA Pesticide Factsheets

    La EPA estableció avisos de salud sobre el ácido perfluorooctanoico (PFOA) y el sulfonato de perfluorooctano (PFOS) para proporcionar información a los operadores de sistemas de agua potable y funcionarios estatales, tribales y locales sobre los riesgos de

  3. Informe: Agua potable - la EPA necesita adoptar medidas adicionales para garantizar que los pequeños sistemas de agua comunitarios señalados como graves infractores logren cumplir con las normas

    EPA Pesticide Factsheets

    Informe #16-P-0108, 22 de Marzo de 2016. La EPA puede proteger mejor al público del agua potable contaminada, lo que incluye a casi 200,000 personas en Puerto Rico que todavía carecen de agua potable segura.

  4. Vigilando la Calidad del Agua de los Grandes Rios de la Nacion: El Programa NASQAN del Rio Grande (Rio Bravo del Norte)

    USGS Publications Warehouse

    Lurry, Dee L.; Reutter, David C.; Wells, Frank C.; Rivera, M.C.; Munoz, A.

    1998-01-01

    La Oficina del Estudio Geologico de los Estados Unidos (U.S. Geological Survey, 0 USGS) ha monitoreado la calidad del agua de la cuenca del Rio Grande (Rio Bravo del Norte) desde 1995 como parte de la rediseiiada Red Nacional para Contabilizar la Calidad del Agua de los Rios (National Stream Quality Accounting Network, o NASOAN) (Hooper and others, 1997). EI programa NASOAN fue diseiiado para caracterizar las concentraciones y el transporte de sedimento y constituyentes quimicos seleccionados, encontrados en los grandes rios de los Estados Unidos - incluyendo el Misisipi, el Colorado y el Columbia, ademas del Rio Grande. En estas cuatro cuencas, el USGS opera actualmente (1998) una red de 40 puntos de muestreo pertenecientes a NASOAN, con un enfasis en cuantificar el flujo en masa (la cantidad de material que pasa por la estacion, expresado en toneladas por dial para cada constituyente. Aplicacando un enfoque consistente, basado en la cuantificacion de flujos en la cuenca del Rio Grande, el programa NASOAN esta generando la informacion necesaria para identificar fuentes regionales de diversos contaminantes, incluyendo sustancias qui micas agricolas y trazas elementos en la cuenca. EI efecto de las grandes reservas en el Rio Grande se puede observar segun los flujos de constituyentes discurren a 10 largo del rio. EI analisis de los flujos de constituyentes a escala de la cuenca proveera los medios para evaluar la influencia de la actividad humana sobre las condiciones de calidad del agua del Rio Grande.

  5. Introduccion a la hidraulica de aguas subterraneas : un texto programado para auto-ensenanza

    USGS Publications Warehouse

    Bennett, Gordon D.

    1987-01-01

    Este ' texto programado esta diseflado para ayudarle a comprender la teoria de la hidniulica de aguas subterraneas por medio de la auto-enseflanza. La instrucci6n programada es un enfoque a una materia, un metodo de aprender;que no elimina el esfuerzo mental del proceso de aprendizaje. Algunas secciones de este programa necesitan solamente ser leidas; otras tendrian que ser elaboradas con lapiz y papel. Algunas preguntas pueden ser contestadas directamente; otras requieren calculos. A medida que se avanza en el texto, tendra que consultar frecuentemente textos o referencias sobre matematicas, mecanica de fluidos e hidrologia. En cada una de las ocho partes del texto, inicie el programa de instrucci6n leyendo la Secci6n 1. Elija una respuesta a la pregunta al final de la secci6n y dirijase a la nueva secci6n indicada al lado de la respuesta escogida. Si su respuesta fue correcta, pase a la secci6n que contiene materia nueva y otra pregunta, y proceda tal como en la Secci6n 1. Si su respuesta no fue correcta, dirijase a la secci6n que contiene explicaciones adicionales sobre el tema anterior y que le indica volver a la pregunta inicial e intentar de nuevo. En este caso, valdra Ia pena repasar el material de la secci6n anterior. Continue de esta man era en el programa hasta que llegue a Ia secci6n que indica el final de la parte. Observe que aunque las secciones estan en orden numerico en cada una de las ocho partes, por lo general, usted no procedeni en secuencia numerica (Secci6n 1 ala Secci6n 2, etc.) de principia a fin.

  6. 2. William Beardsley standing along the Agua Fria River near ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. William Beardsley standing along the Agua Fria River near construction site of the Agua Fria project. Photographer James Dix Schuyler, 1903. Source: Schuyler, James D. 'Report on the Water Supply of the Agua Fria River, and the Storage Reservoir Project of the Agua Fria Water and Land Company For Irrigation in the Gila River Valley, Arizona,' (September 29, 1903). Arizona Historical Collection, Hayden Library, Arizona State University, Tempe, Arizona. (Typewritten.) - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  7. 7. Photocopy of map of the Agua Fria Valley and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Photocopy of map of the Agua Fria Valley and lands to be irrigated by the Agua Fria Water and Land Company. Photographer Mark Durben, 1987 Source: 'Map of the Agua Fria Valley and the Western Portion of the Salt River Valley Showing the System of Reservoirs and Canals of the Agua Fria Water and Land Company and the Land to be Irrigated Thereby 160,000 Acres of New Land to be Reclaimed in the Maricopa County, Arizona Territory,' (Brochure) Union Photo Engraving Company, c. 1895, Salt River Project Research Archives, Tempe, Arizona. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  8. Study of heat and salt transport processes in the Espinheiro Channel (Ria de Aveiro)

    NASA Astrophysics Data System (ADS)

    Vaz, Nuno Alexandre Firmino

    O principal objectivo deste trabalho consistiu no estudo da dinâmica termohalina do Canal do Espinheiro em funcao de dois forcamentos principais: mare e caudal fluvial, usando duas abordagens distintas: trabalho experimental e modelacao numerica. A propagacao da mare e o caudal fluvial do Rio Vouga sao determinantes no estabelecimento da estrutura horizontal da salinidade ao longo do canal. A estrutura termica horizontal ao longo do canal e, em grande parte, determinada pela variacao sazonal da temperatura da agua do Rio Vouga, bem como, pela variacao sazonal das condicoes meteorologicas devido a reduzida profundidade. Foi observada a formacao de fortes gradientes de salinidade (relacionados com a formacao de frentes estuarinas) numa regiao a cerca de 7-8 km da embocadura do canal, observando-se a sua migracao numa regiao de aproximadamente 1 km, dependendo do regime de mare. O balanco entre o transporte de sal de natureza advectiva e difusiva foi calculado, revelando que junto a embocadura os processos fisicos que mais contribuem para o transporte de sal sao a circulacao residual e o aprisionamento da agua em canais secundarios. Junto a foz do Rio Vouga os termos devidos a descarga fluvial e a circulacao gravitacional dominam o transporte de sal. Foi calibrado e validado um modelo numerico (Mohid, em modo 2D e 3D), sendo posteriormente utilizado para estudar a hidrologia do canal. Foi concedida particular atencao ao estudo da hidrologia em condicoes extremas de caudal fluvial e de mare. Os resultados da modelacao numerica permitiram numa primeira fase avaliar o bom desempenho do Mohid na reproducao dos escoamentos barotropicos na Ria de Aveiro, bem como na evolucao temporal das propriedades termohalinas da agua. Sob condicoes de caudal fluvial reduzido, a dinâmica do canal e essencialmente dominada pela mare. Com o aumento do caudal fluvial, a influencia da agua doce estende-se para jusante, estratificando a coluna de agua. As simulacoes 3D do Canal do

  9. 72. Headgates for Agua Fria project canal on east end ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. Headgates for Agua Fria project canal on east end of diversion dam. Photographer Mark Durben. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  10. 54. Downstream face of Agua Fria project's diversion dam showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. Downstream face of Agua Fria project's diversion dam showing initial masonry construction and poured concrete capping. Photographer Mark Durben, 1986. Source: Salt River Project. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  11. Regulation of the alpha-glucuronidase-encoding gene ( aguA) from Aspergillus niger.

    PubMed

    de Vries, R P; van de Vondervoort, P J I; Hendriks, L; van de Belt, M; Visser, J

    2002-09-01

    The alpha-glucuronidase gene aguA from Aspergillus niger was cloned and characterised. Analysis of the promoter region of aguA revealed the presence of four putative binding sites for the major carbon catabolite repressor protein CREA and one putative binding site for the transcriptional activator XLNR. In addition, a sequence motif was detected which differed only in the last nucleotide from the XLNR consensus site. A construct in which part of the aguA coding region was deleted still resulted in production of a stable mRNA upon transformation of A. niger. The putative XLNR binding sites and two of the putative CREA binding sites were mutated individually in this construct and the effects on expression were examined in A. niger transformants. Northern analysis of the transformants revealed that the consensus XLNR site is not actually functional in the aguA promoter, whereas the sequence that diverges from the consensus at a single position is functional. This indicates that XLNR is also able to bind to the sequence GGCTAG, and the XLNR binding site consensus should therefore be changed to GGCTAR. Both CREA sites are functional, indicating that CREA has a strong influence on aguA expression. A detailed expression analysis of aguA in four genetic backgrounds revealed a second regulatory system involved in activation of aguA gene expression. This system responds to the presence of glucuronic and galacturonic acids, and is not dependent on XLNR.

  12. Agua Caliente and Their Music.

    ERIC Educational Resources Information Center

    Ryterband, Roman

    1979-01-01

    Discusses the traditional music of the Agua Caliente band of California's Desert Cahuilla Indian tribe, including accompanying instruments, types of songs, thematic material, and performance routines. Exploring the structure of the music, the article describes meter, tempo, harmony and tonal gravitations, and use of words. (DS)

  13. Geologie study off gravels of the Agua Fria River, Phoenix, AZ

    USGS Publications Warehouse

    Langer, W.H.; Dewitt, E.; Adams, D.T.; O'Briens, T.

    2010-01-01

    The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basin’s main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

  14. [Water birds from Agua Dulce lake and El Ermitaño estuary, Jalisco, Mexico].

    PubMed

    Hernández Vázquez, Salvador

    2005-01-01

    Waterbird abundance, and seasonal and spatial distribution, were studied in two natural water pools at Jalisco, Mexico, from December 1997 through November 1998. Maximum monthly abundance in Agua Dulce lake and El Ermitaño estuary was 86 471 birds (29 686 in Agua Dulce and 56 785 in Ermitaño), with a total cummulative abundance of 179 808 individuals (66 976 in Agua Dulce and 112 832 in Ermitaño). A total of 87 waterbirds species were recorded, 78 in Agua Dulce and 73 in Ermitaño. The higher species richness and abundance was observed during winter, when migratory species arrived. Most species prefered shallow waters, except seabirds which prefered protected areas such as dunes in Agua Dulce. Other groups, like clucks and related species. prefered low salinity areas, for example in the south-east area of Ermitaño. The higher abundance of the shorehirds was found when the water level on the estuary was low. Herons were seen often at areas with high salinity and influenced by tides (e.g. mouth of Ermitaño).

  15. 75 FR 21034 - Notice of Availability of Record of Decision for the Agua Fria National Monument and Bradshaw...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ....241A] Notice of Availability of Record of Decision for the Agua Fria National Monument and Bradshaw... availability of the Record of Decision (ROD)/Approved Resource Management Plan (RMP) for the Agua Fria National... of the planning area during prehistoric or historic times. The Agua Fria National Monument includes...

  16. Energia Renovable para Centros de Salud Rurales (Renewable Energy for Rural Health Clinics) (in Spanish)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jimenez, T.; Olson, K.

    Esta es la primera de una serie de guias de aplicaciones que el Programa de Energia de Villas de NREL esta comisionando para acoplar sistemas comerciales renovables con aplicaciones rurales, incluyendo agua, escuelas rurales y micro empresas. La guia esta complementada por las actividades de desarrollo del Programa de Energia de Villas de NREL, proyectos pilotos internacionales y programas de visitas profesionales.

  17. The source, discharge, and chemical characteristics of water from Agua Caliente Spring, Palm Springs, California

    USGS Publications Warehouse

    Brandt, Justin; Catchings, Rufus D.; Christensen, Allen H.; Flint, Alan L.; Gandhok, Gini; Goldman, Mark R.; Halford, Keith J.; Langenheim, V.E.; Martin, Peter; Rymer, Michael J.; Schroeder, Roy A.; Smith, Gregory A.; Sneed, Michelle; Martin, Peter

    2011-01-01

    Agua Caliente Spring, in downtown Palm Springs, California, has been used for recreation and medicinal therapy for hundreds of years and currently (2008) is the source of hot water for the Spa Resort owned by the Agua Caliente Band of the Cahuilla Indians. The Agua Caliente Spring is located about 1,500 feet east of the eastern front of the San Jacinto Mountains on the southeast-sloping alluvial plain of the Coachella Valley. The objectives of this study were to (1) define the geologic structure associated with the Agua Caliente Spring; (2) define the source(s), and possibly the age(s), of water discharged by the spring; (3) ascertain the seasonal and longer-term variability of the natural discharge, water temperature, and chemical characteristics of the spring water; (4) evaluate whether water-level declines in the regional aquifer will influence the temperature of the spring discharge; and, (5) estimate the quantity of spring water that leaks out of the water-collector tank at the spring orifice.

  18. The Agua Salud Project, Central Panama

    NASA Astrophysics Data System (ADS)

    Stallard, R. F.; Elsenbeer, H.; Ogden, F. L.; Hall, J. S.

    2007-12-01

    The Agua Salud Project utilizes the Panama Canal's central role in world commerce to focus global attention on the ecosystem services provided by tropical forests. It will be the largest field experiment of its kind in the tropics aimed at quantifying the environmental services (water, carbon, and biodiversity) provided by tropical forests. The Agua Salud Watershed is our principal field site. This watershed and the headwaters of several adjacent rivers include both protected mature forests and a wide variety of land uses that are typical of rural Panama. Experiments at the scale of entire catchments will permit complete water and carbon inventories and exchanges for different landscape uses. The following questions will be addressed: (1) How do landscape treatments and management approaches affect ecosystem services such as carbon storage, water quality and quantity, dry- season water supply, and biodiversity? (2) Can management techniques be designed to optimize forest production along with ecosystem services during reforestation? (3) Do different tree planting treatments and landscape management approaches influence groundwater storage, which is thought to be critical to maintaining dry-season flow, thus insuring the full operation of the Canal during periods of reduced rainfall and severe climatic events such as El Niño. In addition we anticipate expanding this project to address biodiversity, social, and economic values of these forests.

  19. AGUA TIBIA PRIMITIVE AREA, CALIFORNIA.

    USGS Publications Warehouse

    Irwin, William P.; Thurber, Horace K.

    1984-01-01

    The Agua Tibia Primitive Area in southwestern California is underlain by igneous and metamorphic rocks that are siilar to those widely exposed throughout much of the Peninsular Ranges. To detect the presence of any concealed mineral deposits, samples of stream sediments were collected along the various creeks that head in the mountain. As an additional aid in evaluating the mineral potential, an aeromagnetic survey was made and interpreted. A search for records of past or existing mining claims within the primitive area was made but none was found. Evidence of deposits of metallic or nonmetallic minerals was not seen during the study.

  20. Agua Caliente Solar Feasibility and Pre-Development Study Final Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carolyn T. Stewart, Managing Partner; Red Mountain Energy Partners

    2011-04-26

    Evaluation of facility- and commercial-scale solar energy projects on the Agua Caliente Band of Cahuilla Indians Reservation in Palm Springs, CA. The Agua Caliente Band of Cahuilla Indians (ACBCI) conducted a feasibility and pre-development study of potential solar projects on its lands in southern California. As described below, this study as a logical and necessary next step for ACBCI. Support for solar project development in California, provided through the statewide California Solar Initiative (CSI), its Renewable Portfolio Standard and Feed-in Tariff Program, and recently announced Reverse Auction Mechanism, provide unprecedented support and incentives that can be utilized by customers ofmore » California's investor-owned utilities. Department of Energy (DOE) Tribal Energy Program funding allowed ACBCI to complete its next logical step to implement its Strategic Energy Plan, consistent with its energy and sustainability goals.« less

  1. SEISMIC STUDY OF THE AGUA DE PAU GEOTHERMAL PROSPECT, SAO MIGUEL, AZORES.

    USGS Publications Warehouse

    Dawson, Phillip B.; Rodrigues da Silva, Antonio; Iyer, H.M.; Evans, John R.

    1985-01-01

    A 16 station array was operated over the 200 km**2 central portion of Sao Miguel utilizing 8 permanent Instituto Nacional de Meterologia e Geofisica stations and 8 USGS portable stations. Forty four local events with well constrained solutions and 15 regional events were located. In addition, hundreds of unlocatable seismic events were recorded. The most interesting seismic activity occurred in a swarm on September 6 and 7, 1983 when over 200 events were recorded in a 16 hour period. The seismic activity around Agua de Pau was centered on the east and northeast slopes of the volcano. The data suggest a boiling hydrothermal system beneath the Agua de Pau volcano, consistent with a variety of other data.

  2. Use of Archival Sources to Improve Water-Related Hazard Assessments at Volcán de Agua, Guatemala

    NASA Astrophysics Data System (ADS)

    Hutchison, A. A.; Cashman, K. V.; Rust, A.; Williams, C. A.

    2013-12-01

    This interdisciplinary study focuses on the use of archival sources from the 18th Century Spanish Empire to develop a greater understanding of mudflow trigger mechanisms at Volcán de Agua in Guatemala. Currently, hazard assessments of debris flows at Volcán de Agua are largely based on studies of analogous events, such as the mudflow at Casita Volcano in 1998 caused by excessive rainfall generated by Hurricane Mitch. A preliminary investigation of Spanish archival sources, however, indicates that a damaging mudflow from the volcano in 1717 may have been triggered by activity at the neighbouring Volcán de Fuego. A VEI 4 eruption of Fuego in late August 1717 was followed by 33 days of localized 'retumbos' and then a major local earthquake with accompanying mudflows from several 'bocas' on the southwest flank of Agua. Of particular importance for this study is an archival source from Archivos Generales de Centro América (AGCA) that consists of a series of letters, petitions and witness statements that were written and gathered following the catastrophic events of 1717. Their purpose was to argue for royal permission to relocate the capital city, which at the time was located on the lower flanks of Volcán de Agua. Within these documents there are accounts of steaming 'avenidas' of water with sulphurous smells, and quantitative descriptions that suggest fissure formation related to volcanic activity at Volcán de Fuego. Clear evidence for volcano-tectonic activity at the time, combined with the fact there is no mention of rainfall in the documents, suggest that outbursts of mud from Agua's south flank may have been caused by a volcanic perturbation of a hydrothermal system. This single example suggests that further analysis of archival documents will provide a more accurate and robust assessment of water related hazards at Volcán de Agua than currently exists.

  3. The Douro estuarine plume: Detection, processes and dynamics =

    NASA Astrophysics Data System (ADS)

    Mendes, Renato Paulo dos Santos

    O Douro e um dos maiores rios da Peninsula Iberica, constituindo a maior descarga de agua doce para o Oceano Atlântico na costa noroeste portuguesa. A sua pluma estuarina tem particular relevância na dinâmica costeira e na modulacao de fenomenos biogeoquimicos. Sao objetivos desta dissertacao contribuir para a compreensao dos processos fisicos associados a geracao e propagacao da pluma estuarina do Rio Douro no oceano, assim como para o conhecimento dos seus padroes de dispersao e da forma como estes alteram a hidrologia e a circulacao costeira, considerando os agentes forcadores tipicos deste fenomeno (caudal fluvial, vento e mare) e indices climaticos relevantes. Para concretizacao destes objetivos foram desenvolvidas e aplicadas metodologias inovadoras de processamento de dados de detecao remota, assim como novas implementacoes estuarinas e costeiras de modelos numericos. Atraves de imagens MODIS, otimizadas para o estudo de fenomenos costeiros, efetuou-se uma detecao rigorosa da pluma. Identificou-se uma relacao entre o sinal turbido nLw555 e o caudal, demonstrando-se este produto como um bom proxy para a observacao da pluma no oceano. As escalas temporais e espaciais da pluma foram caraterizadas atraves destas imagens, combinadas com dados de caudal fluvial, mare, vento e precipitacao, e tambem com indices climaticos relevantes. Para compreender a propagacao da pluma e caracterizar a sua dinâmica e impacto na circulacao costeira, foi desenvolvida uma aplicacao 3D de modelos estuarinos e costeiros com malhas aninhadas de resolucao variavel. Definiramse e analisaram-se diferentes cenarios de vento e descarga fluvial. A interacao da pluma do Rio Douro e do Minho foi ainda analisada atraves dos resultados de simulacoes baseadas num evento de inverno. Os compositos turbidos mostraram que a pluma e facilmente detetada quando o caudal e maior que 500 m3 s??1. A descarga fluvial e o vento sao os principais forcadores da sua propagacao, enquanto a mare e apenas

  4. Flood of February 1980 along the Agua Fria River, Maricopa County, Arizona

    USGS Publications Warehouse

    Thomsen, B.W.

    1980-01-01

    The flood of February 20, 1980, along the Agua Fria River below Waddell Dam, Maricopa County, Ariz., was caused by heavy rains during February 13-20. The runoff filled Lake Pleasant and resulted in the largest release--66,600 cubic feet per second--from the reservoir since it was built in 1927; the maximum inflow to the reservoir was about 73,300 cubic feet per second. The area inundated by the releases includes about 28 miles along the channel from the mouth of the Agua Fria River to the Beardsley Canal flume crossing 5 miles downstream from Waddell Dam. The flood of 1980 into Lake Pleasant has a recurrence interval of about 47 years, whereas the flood of record (1919) has a recurrence interval of about 100 years. (USGS)

  5. Infórmese sobre el programa de WIFIA

    EPA Pesticide Factsheets

    La Ley de finanzas e innovación de la infraestructura del agua de 2014 estableció el programa de WIFIA, un programa federal crediticio administrado por la EPA para proyectos elegibles de infraestructura de agua y aguas sanitarias.

  6. Hydrologic characteristics of the Agua Fria National Monument, central Arizona, determined from the reconnaissance study

    USGS Publications Warehouse

    Fleming, John B.

    2005-01-01

    Hydrologic conditions in the newly created Agua Fria National Monument were characterized on the basis of existing hydrologic and geologic information, and streamflow data collected in May 2002. The study results are intended to support the Bureau of Land Management's future water-resource management responsibilities, including quantification of a Federal reserved water right within the monument. This report presents the study results, identifies data deficiencies, and describes specific approaches for consideration in future studies. Within the Agua Fria National Monument, the Agua Fria River flows generally from north to south, traversing almost the entire 23-mile length of the monument. Streamflow has been measured continuously at a site near the northern boundary of the monument since 1940. Streamflow statistics for this site, and streamflow measurements from other sites along the Agua Fria River, indicate that the river is perennial in the northern part of the monument but generally is intermittent in downstream reaches. The principal controls on streamflow along the river within the monument appear to be geology, the occurrence and distribution of alluvium, inflow at the northern boundary and from tributary canyons, precipitation, and evapotranspiration. At present, (2004) there is no consistent surface-water quality monitoring program being implemented for the monument. Ground-water recharge within the monument likely results from surface-water losses and direct infiltration of precipitation. Wells are most numerous in the Cordes Junction and Black Canyon City areas. Only eight wells are within the monument. Ground-water quality data for wells in the monument area consist of specific-conductance values and fluoride concentrations. During the study, ground-water quality data were available for only one well within the monument. No ground-water monitoring program is currently in place for the monument or surrounding areas.

  7. Lahar hazards at Agua volcano, Guatemala

    USGS Publications Warehouse

    Schilling, S.P.; Vallance, J.W.; Matías, O.; Howell, M.M.

    2001-01-01

    At 3760 m, Agua volcano towers more than 3500 m above the Pacific coastal plain to the south and 2000 m above the Guatemalan highlands to the north. The volcano is within 5 to 10 kilometers (km) of Antigua, Guatemala and several other large towns situated on its northern apron. These towns have a combined population of nearly 100,000. It is within about 20 km of Escuintla (population, ca. 100,000) to the south. Though the volcano has not been active in historical time, or about the last 500 years, it has the potential to produce debris flows (watery flows of mud, rock, and debris—also known as lahars when they occur on a volcano) that could inundate these nearby populated areas.

  8. Vínculos observacionais para o processo-S em estrelas gigantes de Bário

    NASA Astrophysics Data System (ADS)

    Smiljanic, R. H. S.; Porto de Mello, G. F.; da Silva, L.

    2003-08-01

    Estrelas de bário são gigantes vermelhas de tipo GK que apresentam excessos atmosféricos dos elementos do processo-s. Tais excessos são esperados em estrelas na fase de pulsos térmicos do AGB (TP-AGB). As estrelas de bário são, no entanto, menos massivas e menos luminosas que as estrelas do AGB, assim, não poderiam ter se auto-enriquecido. Seu enriquecimento teria origem em uma estrela companheira, inicialmente mais massiva, que evolui pelo TP-AGB, se auto-enriquece com os elementos do processo-s e transfere material contaminado para a atmosfera da atual estrela de bário. A companheira evolui então para anã branca deixando de ser observada diretamente. As estrelas de bário são, portanto, úteis como testes observacionais para teorias de nucleossíntese pelo processo-s, convecção e perda de massa. Análises detalhadas de abundância com dados de alta qualidade para estes objetos são ainda escassas na literatura. Neste trabalho construímos modelos de atmosferas e, procedendo a uma análise diferencial, determinamos parâmetros atmosféricos e evolutivos de uma amostra de dez gigantes de bário e quatro normais. Determinamos seus padrões de abundância para Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu e Gd, concluindo que algumas estrelas classificadas na literatura como gigantes de bário são na verdade gigantes normais. Comparamos dois padrões médios de abundância, para estrelas com grandes excessos e estrelas com excessos moderados, com modelos teóricos de enriquecimento pelo processo-s. Os dois grupos de estrelas são ajustados pelos mesmos parâmetros de exposição de nêutrons. Tal resultado sugere que a ocorrência do fenômeno de bário com diferentes intensidades não se deve a diferentes exposições de nêutrons. Discutimos ainda efeitos nucleossintéticos, ligados ao processo-s, sugeridos na literatura para os elementos Cu, Mn, V e Sc.

  9. Novel materials based on chitosan, its derivatives and cellulose fibres

    NASA Astrophysics Data System (ADS)

    Fernandes, Susana Cristina de Matos

    O presente trabalho tem como principal objectivo o desenvolvimento de novos materiais baseados em quitosano, seus derivados e celulose, na forma de nanofibras ou de papel. Em primeiro lugar procedeu-se a purificacao das amostras comerciais de quitosano e a sua caracterizacao exaustiva em termos morfologicos e fisicoquimicos. Devido a valores contraditorios encontrados na literatura relativamente a energia de superficie do quitosano, e tendo em conta a sua utilizacao como precursor de modificacoes quimicas e a sua aplicacao em misturas com outros materiais, realizou-se tambem um estudo sistematico da determinacao da energia de superficie do quitosano, da quitina e seus respectivos homologos monomericos, por medicao de ângulos de contacto Em todas as amostras comerciais destes polimeros identificaram-se impurezas nao polares que estao associadas a erros na determinacao da componente polar da energia de superficie. Apos a remocao destas impurezas, o valor da energia total de superficie (gs), e em particular da sua componente polar, aumentou consideravelmente. Depois de purificadas e caracterizadas, algumas das amostras de quitosano foram entao usadas na preparacao de filmes nanocompositos, nomeadamente dois quitosanos com diferentes graus de polimerizacao, correspondentes derivados soluveis em agua (cloreto de N-(3-(N,N,N-trimetilamonio)-2- hidroxipropilo) de quitosano) e nanofibras de celulose como reforco (celulose nanofibrilada (NFC) e celulose bacteriana (BC). Estes filmes transparentes foram preparados atraves de um processo simples e com conotacao 'verde' pela dispersao homogenea de diferentes teores de NFC (ate 60%) e BC (ate 40%) nas solucoes de quitosano (1.5% w/v) seguida da evaporacao do solvente. Os filmes obtidos foram depois caracterizados por diversas tecnicas, tais como SEM, AFM, difraccao de raio-X, TGA, DMA, ensaios de traccao e espectroscopia no visivel. Estes filmes sao altamente transparentes e apresentam melhores propriedades mecânicas e maior

  10. 76 FR 63614 - Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-13

    ... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-21-000] Agua Caliente Solar, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket... Caliente Solar, LLC's application for market-based rate authority, with an accompanying rate tariff, noting...

  11. Promotion of water consumption in elementary school children in San Diego, USA and Tlaltizapan, Mexico.

    PubMed

    Elder, John P; Holub, Christina K; Arredondo, Elva M; Sánchez-Romero, Luz María; Moreno-Saracho, Jessica E; Barquera, Simón; Rivera, Juan

    2014-01-01

    Consumption of water may help promote health and prevent obesity in children by decreasing consumption of sugar-sweetened beverages. This study used evidence-based strategies to increase water consumption in Mexican-American and Mexican children. In 2012, two schools in San Diego, USA and two other in Tlaltizapan, Mexico were recruited to Agua para Niños (Water for Kids), a program designed to promote water consumption among elementary grade students. Guided by operant psychology, the intervention focused on school and classroom activities to encourage water consumption. One control and one intervention school in each country were included. Agua para Niños resulted in increases in observed water consumption and bottle possession among US and Mexican students. Teacher receptivity to the program was very positive in both countries. Agua para Niños yielded sufficiently positive behavioral changes to be used in a future fully randomized design, and to contribute to school nutrition policy changes.

  12. ¿Qué está haciendo la EPA para proteger a los arrecifes de coral?

    EPA Pesticide Factsheets

    La EPA protege a los arrecifes de coral mediante la implementación de programas de la Ley de Agua Limpia que protegen la calidad del agua en cuencas y zonas costeras de las áreas con arrecifes de coral.

  13. Astronomia para/com crianças carentes em Limeira

    NASA Astrophysics Data System (ADS)

    Bretones, P. S.; Oliveira, V. C.

    2003-08-01

    Em 2001, o Instituto Superior de Ciências Aplicadas (ISCA Faculdades de Limeira) iniciou um projeto pelo qual o Observatório do Morro Azul empreendeu uma parceria com o Centro de Promoção Social Municipal (CEPROSOM), instituição mantida pela Prefeitura Municipal de Limeira para atender crianças e adolescentes carentes. O CEPROSOM contava com dois projetos: Projeto Centro de Convivência Infantil (CCI) e Programa Criança e Adolescente (PCA), que atendiam crianças e adolescentes em Centros Comunitários de diversas áreas da cidade. Esses projetos têm como prioridades estabelecer atividades prazerosas para as crianças no sentido de retirá-las das ruas. Assim sendo, as crianças passaram a ter mais um tipo de atividade - as visitas ao observatório. Este painel descreve as várias fases do projeto, que envolveu: reuniões de planejamento, curso de Astronomia para as orientadoras dos CCIs e PCAs, atividades relacionadas a visitas das crianças ao Observatório, proposta de construção de gnômons e relógios de Sol nos diversos Centros Comunitários de Limeira e divulgação do projeto na imprensa. O painel inclui discussões sobre a aprendizagem de crianças carentes, relatos que mostram a postura das orientadoras sobre a pertinência do ensino de Astronomia, relatos do monitor que fez o atendimento no Observatório e o que o número de crianças atendidas representou para as atividades da instituição desde o início de suas atividades e, em particular, em 2001. Os resultados são baseados na análise de relatos das orientadoras e do monitor do Observatório, registros de visitas e matérias da imprensa local. Conclui com uma avaliação do que tal projeto representou para as Instituições participantes. Para o Observatório, em particular, foi feita uma análise com relação às outras modalidades de atendimentos que envolvem alunos de escolas e público em geral. Também é abordada a questão do compromisso social do Observatório na educação do

  14. The Laramide Mesa formation and the Ojo de Agua caldera, southeast of the Cananea copper mining district, Sonora, Mexico

    USGS Publications Warehouse

    Cox, Dennis P.; Miller, Robert J.; Woodbourne, Keith L.

    2006-01-01

    The Mesa Formation extends from Cananea, Mexico, southeast to the Sonora River and is the main host rock of Laramide porphyry copper deposits in the Cananea District and at the Alacran porphyry prospect to the east. The Mesa consists of two members-a lower andesite and an upper dacite. The lowest part of the dacite member is a crystal tuff about 100 m thick. This tuff is the outfall of a caldera centered near the village of Ojo de Agua, dated by 40Ar/39Ar at 65.8 Ma ?0.4. The Ojo de Agua Caldera is about 9 km in diameter and is filled by a light gray biotite dacite tuff with abundant flattened pumice fragments. The volume of the caldera is estimated to be 24 km3.

  15. Chihuahuan desert flora of La Calera, Municipio de Agua Prieta, Sonora, Mexico

    Treesearch

    Ana Lilia Reina-Guerrero; Thomas R. Van Devender

    2013-01-01

    A total of 555 plant collections were made on 20 trips in 2002-2008 to La Calera area in the Sierra Anibácachi, Municipio de Agua Prieta, 11.3 km south of the Arizona border (31°13’59”N 109°37’53”W, elevation range from 1220 m to 1539 m) in northeastern Sonora. Chihuahuan desertscrub on limestone substrates is dominated by creosotebush (Larrrea divaricata), Chihuahuan...

  16. aguA, the gene encoding an extracellular alpha-glucuronidase from Aspergillus tubingensis, is specifically induced on xylose and not on glucuronic acid.

    PubMed

    de Vries, R P; Poulsen, C H; Madrid, S; Visser, J

    1998-01-01

    An extracellular alpha-glucuronidase was purified and characterized from a commercial Aspergillus preparation and from culture filtrate of Aspergillus tubingensis. The enzyme has a molecular mass of 107 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 112 kDa as determined by mass spectrometry, has a determined pI just below 5.2, and is stable at pH 6.0 for prolonged times. The pH optimum for the enzyme is between 4.5 and 6.0, and the temperature optimum is 70 degrees C. The alpha-glucuronidase is active mainly on small substituted xylo-oligomers but is also able to release a small amount of 4-O-methylglucuronic acid from birchwood xylan. The enzyme acts synergistically with endoxylanases and beta-xylosidase in the hydrolysis of xylan. The enzyme is N glycosylated and contains 14 putative N-glycosylation sites. The gene encoding this alpha-glucuronidase (aguA) was cloned from A. tubingensis. It consists of an open reading frame of 2,523 bp and contains no introns. The gene codes for a protein of 841 amino acids, containing a eukaryotic signal sequence of 20 amino acids. The mature protein has a predicted molecular mass of 91,790 Da and a calculated pI of 5.13. Multiple copies of the gene were introduced in A. tubingensis, and expression was studied in a highly overproducing transformant. The aguA gene was expressed on xylose, xylobiose, and xylan, similarly to genes encoding endoxylanases, suggesting a coordinate regulation of expression of xylanases and alpha-glucuronidase. Glucuronic acid did not induce the expression of aguA and also did not modulate the expression on xylose. Addition of glucose prevented expression of aguA on xylan but only reduced the expression on xylose.

  17. aguA, the Gene Encoding an Extracellular α-Glucuronidase from Aspergillus tubingensis, Is Specifically Induced on Xylose and Not on Glucuronic Acid

    PubMed Central

    de Vries, Ronald P.; Poulsen, Charlotte H.; Madrid, Susan; Visser, Jaap

    1998-01-01

    An extracellular α-glucuronidase was purified and characterized from a commercial Aspergillus preparation and from culture filtrate of Aspergillus tubingensis. The enzyme has a molecular mass of 107 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 112 kDa as determined by mass spectrometry, has a determined pI just below 5.2, and is stable at pH 6.0 for prolonged times. The pH optimum for the enzyme is between 4.5 and 6.0, and the temperature optimum is 70°C. The α-glucuronidase is active mainly on small substituted xylo-oligomers but is also able to release a small amount of 4-O-methylglucuronic acid from birchwood xylan. The enzyme acts synergistically with endoxylanases and β-xylosidase in the hydrolysis of xylan. The enzyme is N glycosylated and contains 14 putative N-glycosylation sites. The gene encoding this α-glucuronidase (aguA) was cloned from A. tubingensis. It consists of an open reading frame of 2,523 bp and contains no introns. The gene codes for a protein of 841 amino acids, containing a eukaryotic signal sequence of 20 amino acids. The mature protein has a predicted molecular mass of 91,790 Da and a calculated pI of 5.13. Multiple copies of the gene were introduced in A. tubingensis, and expression was studied in a highly overproducing transformant. The aguA gene was expressed on xylose, xylobiose, and xylan, similarly to genes encoding endoxylanases, suggesting a coordinate regulation of expression of xylanases and α-glucuronidase. Glucuronic acid did not induce the expression of aguA and also did not modulate the expression on xylose. Addition of glucose prevented expression of aguA on xylan but only reduced the expression on xylose. PMID:9440512

  18. Spectroscopic and structural studies of a new para-iodo-N-benzyl amide of salinomycin

    NASA Astrophysics Data System (ADS)

    Antoszczak, Michał; Janczak, Jan; Rutkowski, Jacek; Brzezinski, Bogumił; Huczyński, Adam

    2017-11-01

    A new para-iodo-N-benzyl amide of salinomycin was synthesized and characterized by NMR, FT-IR, DFT, single crystal X-ray diffraction and theoretical methods. The results obtained for the crystal, in solution and in gas phase provided evidence of pseudo-cyclic structure of this compound stabilized by intramolecular hydrogen bonds. It was shown that the compound studied forms stable 1:1 complexes with monovalent (Li+, Na+, K+, Rb+ and Cs+) and divalent (Mg2+, Ca2+, Sr2+ and Ba2+) cations demonstrating that the chemical modification of salinomycin carboxyl group considerably changes the ionophoretic properties of this antibiotic. For the first time, the ESI MS fragmentations of the complex of para-iodo-N-benzyl amide of salinomycin with Na+ are also discussed in details.

  19. Does Para-chloroaniline Really Form after Mixing Sodium Hypochlorite and Chlorhexidine?

    PubMed

    Orhan, Ekim Onur; Irmak, Özgür; Hür, Deniz; Yaman, Batu Can; Karabucak, Bekir

    2016-03-01

    Mixing sodium hypochlorite (NaOCl) with chlorhexidine (CHX) forms a brown-colored precipitate. Previous studies are not in agreement whether this precipitate contains para-chloroaniline (PCA). Tests used for analysis may demonstrate different outcomes. Purpose of this study was to determine whether PCA is formed through the reaction of mixing NaOCl and CHX by using high performance liquid chromatography, proton nuclear magnetic resonance spectroscopy, gas chromatography, thin layer chromatography, infrared spectroscopy, and gas chromatography/mass spectrometry. To obtain a brown precipitate, 4.99% NaOCl was mixed with 2.0% CHX. This brown precipitate was analyzed and compared with signals obtained from commercially available 4.99% NaOCl, 2% solutions, and 98% PCA in powder form. Chromatographic and spectroscopic analyses showed that brown precipitate does not contain free PCA. This study will be a cutoff proof for the argument on PCA formation from reaction of CHX and NaOCl. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Development cooperation in water and sanitation: is it based on the human rights framework?

    PubMed

    Brown, Colin; Heller, Léo

    2017-07-01

    The water and sanitation sector is verifiably receiving increased attention and funding through international development cooperation. Not least because of the way that it affects incentives and institutions in partner countries, development cooperation can have either positive or negative effects on human rights though. The consolidated frameworks for the human rights to water and sanitation is becoming linked to the international community's coordinated development efforts, as evidenced notably in the 2030 Agenda for Sustainable Development. However, a review of major funders' official policies for development cooperation in the sector suggests that many only partially endorse the frameworks for the human rights to water and sanitation. An observation of development cooperation flows to the sector allows the hypothesis to be advanced that worldwide inequalities in access to these services may be reduced through a full and clear application of the human rights framework in development cooperation activities. The article presents findings of this research and explores key stakes for development cooperation in the water and sanitation sector that are relevant for their ability to either negatively or positively contribute to the realization of human rights. Resumen El sector de agua y saneamiento ha recibido creciente atención y financiación a través de la cooperación internacional para el desarrollo. La cooperación para el desarrollo puede tener efectos tanto positivos cuanto negativos sobre los derechos humanos. El hito que consolida los derechos humanos al agua y al saneamiento están articulados a esfuerzos de cooperación para el desarrollo promovidos por la comunidad internacional, como se evidencia en la Agenda 2030 para el Desarrollo Sostenible. Sin embargo, una revisión de las políticas oficiales de los principales financiadores del sector sugiere que muchos de ellos aprueban solo parcialmente los hitos de los derechos humanos al agua y el

  1. [Active search for leprosy and other skin diseases in school children from Agua de Dios, Colombia].

    PubMed

    Rodríguez, Gerzaín; González, Rosalba; Gonzalez, Deysy; Granados, Carolina; Pinto, Rafael; Herrera, Hilda; Gutiérrez, Luisa F; Hernández, Elkin; López, Fernando; Gómez, Yenny

    2007-01-01

    Actively searching for leprosy, other skin diseases and BCG vaccination scars amongst school children from Agua de Dios, the municipality having the highest prevalence of leprosy in Colombia. A clinical examination of the children was carried out by nurses, interns, general practitioners and experts on leprosy. Skin smear tests and skin biopsies were performed when the clinical findings suggested leprosy. Anti-phenolic glycolipid antibodies in blood were determined in special cases. 86 % of the 2 844 school children were examined; 833 had skin diseases and 16 % of these required evaluation by specialists. Four new cases of paucibacillary leprosy, two indeterminate and two primary polyneuritic cases were found. Pediculosis capitis, pityriasis alba, tinea versicolor, hypopigmented nevus, insect bites and miliaria were frequently detected. BCG vaccination scars were absent in 387 children; following several logistical problems, they were vaccinated. Four children had signs of childhood abuse. An 11-year-old girl presented hypopigmented mycosis fungoides. All diseases and conditions found were treated. The community received information regarding the results, emphasising the importance of an early diagnosis of leprosy. The incidence of leprosy found (16/10,000) was 123 times higher than the rest of the country's incidence. It is advisable to continue clinical examinations in Agua de Dios and research into risk factors for acquiring leprosy.

  2. Melhoramentos no código Wilson-Devinney para binárias eclipsantes

    NASA Astrophysics Data System (ADS)

    Vieira, L. A.; Vaz, L. P. R.

    2003-08-01

    A análise de curvas de luz e velocidades radiais de sistemas binários eclipsantes pode ser feita por meio de vários modelos. Um desses é o Modelo Wilson-Devinney (WD). Ao longo dos anos, esse modelo sofreu várias alterações em seus códigos principais, com a finalidade de torná-lo mais consistente tanto fíisica como numericamente. O Modelo WD tem sido melhorado de várias maneiras em seus dois códigos: um para a predição das curvas de luz teórica e de velocidade radiais e outra para as soluções destas curvas. Teoricamente, na física do modelo, nós introduzimos a possibilidade de levar em conta os efeitos do movimento apsidal. Numericamente, nós introduzimos a possibilidade de usar o Método SIMPLEX no procedimento da solução, como uma alternativa para o já implementado Método de Mínimos Quadrados (Least Squares Method). Estas modificações, juntamente com outras já introduzidas pelo nosso grupo anteriormente, tornam o código mais eficiente na solução das curvas de luz e de velocidade radiais de binárias eclipsantes. Como o modelo tem sido usado para analisar sistemas com componentes pré-sequência principal (TY CrA, Casey et al. 1998, Vaz et al. 1998), SM 790, Stassun et al. 2003), este melhoramento beneficiará estes casos também. Apresentamos os resultados obtidos com a modificação do código WD por meio do uso de dados da estrela GL Carinae, comprovando, (1) que os parâmetros orbitais calculados por nós são coerentes com os obtidos anteriormente na literatura (Giménez & Clausen, 1986) e com os obtidos por Faria (1987), e (2) que a implementação do Método SIMPLEX torna o código mais lento mas completamente consistente internamente e evita os problemas gerados pelo uso do Método de Mínimos Quadrados, tais como imprecisão no cálculo das derivadas parciais e convergência para mínimos locais.

  3. Avaliação da influência de alterações cardíacas na ultrassonografia vascular periférica de idosos

    PubMed Central

    Ribeiro, Alcides José Araújo; Ribeiro, Andréa Campos de Oliveira; Rodrigues, Márcia Marisia Maciel; Negreiros, Sandra de Barros Cobra; Nogueira, Ana Cláudia Cavalcante; Almeida, Osório Luís Rangel; Silva, José Carlos Quináglia e; de Paula, Ana Patrícia

    2016-01-01

    Resumo Contexto As cardiopatias podem causar alterações no formato das ondas da ultrassonografia vascular (UV) em vasos periféricos. Essas alterações, tipicamente bilaterais e sistêmicas, são pouco conhecidas e estudadas. Objetivo Avaliar as ondas periféricas da UV de pacientes idosos para identificar alterações decorrentes de cardiopatias. Métodos Foram estudados 183 pacientes idosos submetidos a UV periférica no ano de 2014. Resultados Foram avaliados 102 mulheres (55,7%) e 81 homens (44,3%) com idade entre 60 e 91 anos (média de 70,4±7,2 anos). Encontraram-se alterações pela UV em 84 pacientes (45,9%). Foram identificadas 138 alterações de oito dos 13 tipos descritos na literatura: arritmia, onda bisferiens de pico sistólico, baixa velocidade de pico sistólico, pulsatilidade em veias femorais, bradicardia, taquicardia, onda de pulso parvus tardus e onda de pulso alternans. Houve baixa concordância entre a presença e a não presença de alterações na UV e na avaliação cardiológica. Na análise específica das alterações, os exames tiveram uma concordância variável, que foi boa para o achado de taquicardia, moderada para arritmia e baixa para bradicardia. Não houve concordância entre a UV e os exames cardiológicos para as demais alterações. Conclusões É possível identificar determinadas alterações cardíacas em idosos por meio da análise do formato das ondas periféricas da UV. É importante reconhecer e relatar a presença dessas alterações, pela possibilidade de alertar para um diagnóstico ainda não identificado nesses pacientes. Entretanto, mais estudos são necessários para que seja definida a importância das alterações no formato das ondas Doppler periféricas no reconhecimento de cardiopatias. PMID:29930591

  4. Impacts of Climate Change on Colombia’s National and Regional Security

    DTIC Science & Technology

    2009-10-01

    Peru, and Chile have relatively diverse, industrialized economies and greater domestic resources and state capaci- ties for adaptation. Bolivia...Change on Colombia’s National and Regional Security References 1 Colombia, Sistema de Informacion sobre el Uso del Agua en la Agricultura y el Medio...Jul 2009. "El cambio climatico en Colombia." Unpublished report shared with authors. IDEAM. 26 "El agua para 40 millones de personas esta en riesgo

  5. An Eco-hydrologic Assessment of Small Experimental Catchments with Various Land Uses within the Panama Canal Watershed: Agua Salud Project

    NASA Astrophysics Data System (ADS)

    Crouch, T. D.; Ogden, F. L.; Stallard, R. F.; Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project

    2010-12-01

    Hydrological processes in the humid tropics are poorly understood and an important topic when it comes to water management in the seasonal tropics. The Smithsonian Tropical Research Institute, Panama Canal Watershed Experiment, Agua Salud Project, seeks to understand these processes and quantify the long-term effects of different land cover and uses across the Panama Canal Watershed. One of the project’s main objectives is to understand how reforestation effects seasonal stream flows. To meet this objective, a baseline characterization of hydrology on the small catchment scale is being assessed across different land uses typical in rural Panama. The small experimental catchments are found within Panama’s protected Soberania National Park and the adjacent headwaters of the Agua Salud and Mendoza Rivers, all of which are part of the greater Panama Canal Watershed. The land uses being monitored include a variety of control catchments as well as treated pasture sites. The catchments used for this study include a mature old regrowth forest, a 50% deforested or mosaic regrowth site, an active pasture and a monoculture invasive grass site (saccharum spontaneum) as experimental controls and two treated catchments that were recently abandoned pastures converted to teak and native species timber plantations. Installed instrumentation includes a network of rain gauges, v-notched weirs, atmometers, an eddy covariance system and an assortment of meteorological and automated geochemical sampling systems. Spatial, rainfall, runoff and ET data across these six geologically and topographically similar catchments are available from 2009 and 2010. Classic water balance and paired catchment techniques were used to compare the catchments on an annual, seasonal, and event basis. This study sets the stage for hydrologic modeling and for better understanding the effects of vegetation and land-use history on rainfall-runoff processes for the Agua Salud Project and Panama Canal

  6. Wirelessly controlled micro- and nanostructures for bioapplications

    NASA Astrophysics Data System (ADS)

    Lindo, Andre Machado

    Apresentar uma contribuicao para a caracterizacao e compreensao do comportamento hidrodinâmico da laguna Ria de Aveiro, baseada num estudo experimental e num estudo de modelacao numerica, e o objectivo deste trabalho. As caracteristicas hidrologicas da Ria de Aveiro foram investigadas atraves da realizacao de varias campanhas de amostragem, tendo sido efectuadas medicoes de altura de agua, salinidade, temperatura da agua e velocidade da corrente em varias estacoes distribuidas ao longo de quatro canais principais da laguna. None

  7. Papers Selected for Presentation at the International Symposium on Remote Sensing of Environment (16th) Held at Buenos Aires, Argentina on 2-9 June 1982. Volume 2.

    DTIC Science & Technology

    1982-06-01

    ARGENTINA Oscar Dominguez and Stella Carballo .............. 355 STUDIES ON SOME URBAN PROBLEMS USING AIRBORNE REMOTE SENSORS IN SANTIAGO, CHILE ...SAN JUAN ARGENTINA) (1) Silvia Lendaro de Gianni (2,3) Enrique Uliarte (I) Centro Regional de Agua Subterrgnea (2) Universidad Nacional de San Juan act...Hidrogeol6gico para refuerzo do la provisi6n de agua " a Puerto Deseado. In4dito. - Pezzuchi, Hugo Daniel (1978) "studio Geol6gico de la zona de Lstancia Dos

  8. Hydrochemistry of waters from five cenotes and evaluation of their suitability for drinking-water supplies, northeastern Yucatan, Mexico

    NASA Astrophysics Data System (ADS)

    Alcocer, Javier; Lugo, Alfonso; Marín, Luis E.; Escobar, Elva

    Waters from five cenotes that are currently being used for aquatic recreational activities and that lie along the Cancun-Tulum touristic corridor, Mexico, were evaluated hydrochemically to determine whether the cenotes may be considered as potential drinking-water sources. Several parameters exceed the Mexican Drinking Water Standards (MDWS), but since they do not pose a significant health threat, four of the five cenotes may be used as drinking-water sources. The common contaminants in the Yucatan Peninsula, fecal coliforms and nitrate, are in most cases below the MDWS (0-460 MPN/100ml and 0.31-1.18mg/L, respectively). Although these four cenotes meet the MDWS, a careful groundwater management policy needs to be developed to avoid contamination (fecal and nitrates) and salt-water intrusion. Résumé Les eaux de cinq cénotés, qui sont normalement utilisées pour des activités de plein air, dans la région touristique de Cancun-Tulum (Mexique), ont été soumises à analyses chimiques pour savoir si les cénotés peuvent être considérés comme des sources d'eau potable. Plusieurs paramètres dépassent les normes mexicaines en matière d'eau potable; mais comme ceux-ci ne posent pas de problème réel de santé, quatre des cinq cénotés peuvent être captés pour l'eau potable. Les contaminants habituels dans les eaux de la presqu'île du Yucatan, coliformes fécaux et concentrations élevées en nitrate, sont la plupart du temps au-dessous des normes (respectivement 0 à 460 germes/100ml et 0,31 à 1,18mg/l). Bien que ces quatre cénotés satisfassent aux normes, il est nécessaire de mettre en place des règles précises de l'utilisation de l'eau souterraine, afin d'éviter la contamination par les germes fécaux et par les nitrates, ainsi que l'intrusion marine. Resumen Se analizó hidroquímica y bacteriológicamente el agua de algunos cenotes localizados a lo largo del corredor turístico Cancun-Tulum, que actualmente se utilizan para diversas actividades

  9. Drosophila as a model for intractable epilepsy: gilgamesh suppresses seizures in para(bss1) heterozygote flies.

    PubMed

    Howlett, Iris C; Rusan, Zeid M; Parker, Louise; Tanouye, Mark A

    2013-08-07

    Intractable epilepsies, that is, seizure disorders that do not respond to currently available therapies, are difficult, often tragic, neurological disorders. Na(+) channelopathies have been implicated in some intractable epilepsies, including Dravet syndrome (Dravet 1978), but little progress has been forthcoming in therapeutics. Here we examine a Drosophila model for intractable epilepsy, the Na(+) channel gain-of-function mutant para(bss1) that resembles Dravet syndrome in some aspects (parker et al. 2011a). In particular, we identify second-site mutations that interact with para(bss1), seizure enhancers, and seizure suppressors. We describe one seizure-enhancer mutation named charlatan (chn). The chn gene normally encodes an Neuron-Restrictive Silencer Factor/RE1-Silencing Transcription factor transcriptional repressor of neuronal-specific genes. We identify a second-site seizure-suppressor mutation, gilgamesh (gish), that reduces the severity of several seizure-like phenotypes of para(bss1)/+ heterozygotes. The gish gene normally encodes the Drosophila ortholog of casein kinase CK1g3, a member of the CK1 family of serine-threonine kinases. We suggest that CK1g3 is an unexpected but promising new target for seizure therapeutics.

  10. Chemical response to groundwater extraction southeast of Mexico City

    NASA Astrophysics Data System (ADS)

    Huizar-Alvarez, R.; Carrillo-Rivera, J. J.; Ángeles-Serrano, G.; Hergt, T.; Cardona, A.

    procédure a été appliquée pour caractériser le système d'écoulement souterraine et sa source, les conditions hydrauliques de l'aquifère et la réponse hydraulique des puits considéré. L'analyse de cette information suggérer la présence des systèmes d'écoulement suivantes. (i) local avec18 et 19.5 °C de température, RS de 127-600 mg/L, et Na de 24-178 mg/L, (ii) intermédiaire avec une température de 20 á 22 °C, le RS de 203-940 mg/L et Na 30-370 mg/L, (iii) régional avec 300 à 700 mg/L de RS et 80 à 230 mg/L de Na, une température de 23 à 24.8 °C. Dans le premier cas, l'eau traverse des roches basaltiques, dans le deuxième, des sédiments clastiques avec matière organique de l'aquitard, dans le troisième, des roches volcaniques et calcaires. La chimie de l'eau des quelques puits et sa réponse hydraulique met en évidence l'influence de l'eau de L'aquitard, des effluents de surface et écoulement régional. La conception du régime d'écoulement obtenu, a permis reconnaître les conditions hydrauliques des puits plus correspondantes au contexte hydrogéologique, que si uniquement les données rabattement vs temps auraient été analysé La interpretación conjunta de la gráfica de prueba de bombeo, valores de temperatura y sólidos totales disueltos (STD) del agua subterránea extraída, medidos simultáneamente en campo y la composición química del agua extraída como apoyo adicional; se utilizó como un procedimiento alternativo para interpretar los datos de pruebas de bombeo. Toda esa información fue aplicada para caracterizar el sistema de flujo subterráneo y el origen de éste, las condiciones hidráulicas del acuífero y la respuesta hidráulica de los pozos de extracción. El análisis de la información indica la presencia de: (i) flujo local con temperatura de 18-19.5 °C, STD de 127-600, y Na de 24-178 mg/L (ii) flujo intermedio con temperatura de 20-22 °C, los STD y Na son de (203-940 y 30-370 mg/L), respectivamente; (iii

  11. Riego y fertirriego

    Treesearch

    R. Kasten Dumroese; Thomas D. Landis; Kim M. Wilkinson

    2012-01-01

    El agua es el factor que más puede afectar el crecimiento y la sanidad de las plantas por sí solo. Es esencial para casi todos los procesos vegetales: la fotosíntesis, el transporte de nutrientes, el crecimiento y el desarrollo celular. De hecho, del 80 al 90% del peso de un plantín es agua, por lo cual el manejo del riego es una de las tareas más trascendentes dentro...

  12. Translation and adaptation of the Competencias Esenciales en Salud Pública para los recursos humanos en salud.

    PubMed

    Almeida, Maria de Lourdes de; Peres, Aida Maris; Ferreira, Maria Manuela Frederico; Mantovani, Maria de Fátima

    2017-06-05

    to perform the translation and cultural adaptation of the document named Marco Regional de Competencias Esenciales en Salud Pública para los Recursos Humanos en Salud de la Región de las Américas (Regional Framework of Core Competencies in Public Health for Health Human Resources in the Region of Americas) from Spanish to Brazilian Portuguese. a methodological study comprising the following phases: authorization for translation; initial translation; synthesis of translations and consensus; back-translation and formation of an expert committee. in the translation of domain names, there was no difference in 66.7% (N = 4); in the translation of domain description and competencies there were divergences in 100% of them (N = 6, N = 56). A consensus of more than 80% was obtained in the translation and improvement in the expert committee by the change of words and expressions for approximation of meanings to the Brazilian context. the translated and adapted document has the potential of application in research, and use in the practice of collective/public health care in Brazil. realizar a tradução e adaptação cultural do Marco Regional de Competencias Esenciales en Salud Pública para los Recursos Humanos en Salud de la Región de las Américas, do espanhol para a língua portuguesa do Brasil. pesquisa metodológica, que seguiu as fases: autorização para tradução; tradução inicial; síntese das traduções e consenso; retrotradução e composição de um comitê de especialistas. na tradução dos nomes dos domínios, não houve diferença em 66,7 % (N=4); na tradução da descrição dos domínios e das competências ocorreram divergências em 100 % destes (N=6, N=56), obteve-se consenso acima de 80% ainda na tradução, e aprimoramento no comitê de especialistas pela alteração de palavras e expressões para aproximar os significados ao contexto brasileiro. o documento traduzido e adaptado possui potencial de aplicação em pesquisas e utilização na pr

  13. Quaternary Slip History for the Agua Blanca Fault, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Gold, P. O.; Behr, W. M.; Rockwell, T. K.; Fletcher, J. M.

    2017-12-01

    The Agua Blanca Fault (ABF) is the primary structure accommodating San Andreas-related right-lateral slip across the Peninsular Ranges of northern Baja California. Activity on this fault influences offshore faults that parallel the Pacific coast from Ensenada to Los Angeles and is a potential threat to communities in northern Mexico and southern California. We present a detailed Quaternary slip history for the ABF, including new quantitative constraints on geologic slip rates, slip-per-event, the timing of most recent earthquake, and the earthquake recurrence interval. Cosmogenic 10Be exposure dating of clasts from offset fluvial geomorphic surfaces at 2 sites located along the western, and most active, section of the ABF yield preliminary slip rate estimates of 2-4 mm/yr and 3 mm/yr since 20 ka and 2 ka, respectively. Fault zone geomorphology preserved at the younger site provides evidence for right-lateral surface displacements measuring 2.5 m in the past two ruptures. Luminescence dating of an offset alluvial fan at a third site is in progress, but is expected to yield a slip rate relevant to the past 10 kyr. Adjacent to this third site, we excavated 2 paleoseismic trenches across a sag pond formed by a right step in the fault. Preliminary radiocarbon dates indicate that the 4 surface ruptures identified in the trenches occurred in the past 6 kyr, although additional dating should clarify earthquake timing and the mid-Holocene to present earthquake recurrence interval, as well as the likely date of the most recent earthquake. Our new slip rate estimates are somewhat lower than, but comparable within error to, previous geologic estimates based on soil morphology and geodetic estimates from GPS, but the new record of surface ruptures exposed in the trenches is the most complete and comprehensively dated earthquake history yet determined for this fault. Together with new and existing mapping of tectonically generated geomorphology along the ABF, our constraints

  14. Generation of gas-phase sodiated arenes such as [(Na3(C6H4)+] from benzene dicarboxylate salts.

    PubMed

    Attygalle, Athula B; Chan, Chang-Ching; Axe, Frank U; Bolgar, Mark

    2010-01-01

    Upon collision-induced activation, gaseous sodium adducts generated by electrospray ionization of disodium salts of 1,2- 1,3-, and 1,4-benzene dicarboxylic acids (m/z 233) undergo an unprecedented expulsion of CO(2) by a rearrangement process to produce an ion of m/z 189 in which all three sodium atoms are retained. When isolated in a collision cell of a tandem-in-space mass spectrometer, and subjected to collision-induced dissociation (CID), only the m/z 189 ions derived from the meta and para isomers underwent a further CO(2) loss to produce a peak at m/z 145 for a sodiated arene of formula (Na(3)C(6)H(4))(+). This previously unreported m/z 145 ion, which is useful to differentiate meta and para benzene dicarboxylates from their ortho isomer, is in fact the sodium adduct of phenelenedisodium. Moreover, the m/z 189 ion from all three isomers readily expelled a sodium radical to produce a peak at m/z 166 for a radical cation [(*C(6)H(4)CO(2)Na(2))(+)], which then eliminated CO(2) to produce a peak at m/z 122 for the distonic cation (*C(6)H(4)Na(2))(+). Copyright 2009 John Wiley & Sons, Ltd.

  15. Growth of binary organic NLO crystals: m.NA-p.NA and m.NA-CNA system

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Henningsen, T.; Hopkins, R. H.; Mazelsky, R.

    1993-01-01

    Experiments were carried out to grow 3.Nitroaniline (m.NA) crystals doped with 4.Nitroaniline (p.NA) and 2.chloro 4.Nitroaniline (CNA). The measured undercooling for m.NA, p.NA, and CNA were 0.21 tm K, 0.23 tm K, and 0.35 tm K respectively, where tm represents the melting temperature of the pure component. Because of the crystals' large heat of fusion and large undercooling, it was not possible to grow good quality crystals with low thermal gradients. In the conventional two-zone Bridgman furnace we had to raise the temperature of the hot zone above the decomposition temperature of CNA, p.NA, and m.NA to achieve the desired thermal gradient. To avoid decomposition, we used an unconventional Bridgman furnace. Two immiscible liquids, silicone oil and ethylene glycol, were used to build a special two-zone Bridgman furnace. A temperature gradient of 18 K/cm was achieved without exceeding the decomposition temperature of the crystal. The binary crystals, m.NA-p.NA and m.NA-CNA, were grown in centimeter size in this furnace. X-ray and optical characterization showed good optical quality.

  16. Thermal decomposition of sodium amide, NaNH2, and sodium amide hydroxide composites, NaNH2-NaOH.

    PubMed

    Jepsen, Lars H; Wang, Peikun; Wu, Guotao; Xiong, Zhitao; Besenbacher, Flemming; Chen, Ping; Jensen, Torben R

    2016-09-14

    Sodium amide, NaNH 2 , has recently been shown to be a useful catalyst to decompose NH 3 into H 2 and N 2 , however, sodium hydroxide is omnipresent and commercially available NaNH 2 usually contains impurities of NaOH (<2%). The thermal decomposition of NaNH 2 and NaNH 2 -NaOH composites is systematically investigated and discussed. NaNH 2 is partially dissolved in NaOH at T > 100 °C, forming a non-stoichiometric solid solution of Na(OH) 1-x (NH 2 ) x (0 < x < ∼0.30), which crystallizes in an orthorhombic unit cell with the space group P2 1 2 1 2 1 determined by synchrotron powder X-ray diffraction. The composite xNaNH 2 -(1 - x)NaOH (∼0.70 < x < 0.72) shows a lowered melting point, ∼160 °C, compared to 200 and 318 °C for neat NaNH 2 and NaOH, respectively. We report that 0.36 mol of NH 3 per mol of NaNH 2 is released below 400 °C during heating in an argon atmosphere, initiated at its melting point, T = 200 °C, possibly due to the formation of the mixed sodium amide imide solid solution. Furthermore, NaOH reacts with NaNH 2 at elevated temperatures and provides the release of additional NH 3 .

  17. Condition of Si crystal formation by vaporizing Na from NaSi

    NASA Astrophysics Data System (ADS)

    Morito, Haruhiko; Karahashi, Taiki; Yamane, Hisanori

    2012-09-01

    NaSi was heated at various Na vapor pressures (pNa 0.1-1.2 atm) and temperatures (973-1173 K) to investigate the condition of Si crystal formation from NaSi by Na evaporation. Silicon single crystals 1-3 mm in diameter were grown by evaporation of Na from Na-Si melt at 1173 K and pNa=0.74 atm.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    You, Ya; Yu, Xi -Qian; Yin, Ya -Xia

    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. As a result, 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

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

    DOE PAGES

    You, Ya; Yu, Xi -Qian; Yin, Ya -Xia; ...

    2014-10-27

    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. As a result, 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. Compensatory regulation of Na+ absorption by Na+/H+ exchanger and Na+-Cl- cotransporter in zebrafish (Danio rerio)

    PubMed Central

    2013-01-01

    Introduction In mammals, internal Na+ homeostasis is maintained through Na+ reabsorption via a variety of Na+ transport proteins with mutually compensating functions, which are expressed in different segments of the nephrons. In zebrafish, Na+ homeostasis is achieved mainly through the skin/gill ionocytes, namely Na+/H+ exchanger (NHE3b)-expressing H+-ATPase rich (HR) cells and Na+-Cl- cotransporter (NCC)-expressing NCC cells, which are functionally homologous to mammalian proximal and distal convoluted tubular cells, respectively. The present study aimed to investigate whether or not the functions of HR and NCC ionocytes are differentially regulated to compensate for disruptions of internal Na+ homeostasis and if the cell differentiation of the ionocytes is involved in this regulation pathway. Results Translational knockdown of ncc caused an increase in HR cell number and a resulting augmentation of Na+ uptake in zebrafish larvae, while NHE3b loss-of-function caused an increase in NCC cell number with a concomitant recovery of Na+ absorption. Environmental acid stress suppressed nhe3b expression in HR cells and decreased Na+ content, which was followed by up-regulation of NCC cells accompanied by recovery of Na+ content. Moreover, knockdown of ncc resulted in a significant decrease of Na+ content in acid-acclimated zebrafish. Conclusions These results provide evidence that HR and NCC cells exhibit functional redundancy in Na+ absorption, similar to the regulatory mechanisms in mammalian kidney, and suggest this functional redundancy is a critical strategy used by zebrafish to survive in a harsh environment that disturbs body fluid Na+ homeostasis. PMID:23924428

  1. New geologic slip rates for the Agua Blanca Fault, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Gold, P. O.; Behr, W. M.; Fletcher, J. M.; Hinojosa-Corona, A.; Rockwell, T. K.

    2015-12-01

    Within the southern San Andreas transform plate boundary system, relatively little is known regarding active faulting in northern Baja California, Mexico, or offshore along the Inner Continental Borderland. The inner offshore system appears to be fed from the south by the Agua Blanca Fault (ABF), which strikes northwest across the Peninsular Ranges of northern Baja California. Therefore, the geologic slip rate for the ABF also provides a minimum slip rate estimate for the offshore system, which is connected to the north to faults in the Los Angeles region. Previous studies along the ABF determined slip rates of ~4-6 mm/yr (~10% of relative plate motion). However, these rates relied on imprecise age estimates and offset geomorphic features of a type that require these rates to be interpreted as minima, allowing for the possibility that the slip rate for the ABF may be greater. Although seismically quiescent, the surface trace of the ABF clearly reflects Holocene activity, and given its connectivity with the offshore fault system, more quantitative slip rates for the ABF are needed to better understand earthquake hazard for both US and Mexican coastal populations. Using newly acquired airborne LiDAR, we have mapped primary and secondary fault strands along the segmented western 70 km of the ABF. Minimal development has left the geomorphic record of surface slip remarkably well preserved, and we have identified abundant evidence meter to km scale right-lateral displacement, including new Late Quaternary slip rate sites. We verified potential reconstructions at each site during summer 2015 fieldwork, and selected an initial group of three high potential slip rate sites for detailed mapping and geochronologic analyses. Offset landforms, including fluvial terrace risers, alluvial fans, and incised channel fill deposits, record displacements of ~5-80 m, and based on minimal soil development, none appear older than early Holocene. To quantitatively constrain landform ages

  2. 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

    2013-11-07

    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.

  3. Resumen del programa de WIFIA

    EPA Pesticide Factsheets

    Hojas informativas sobre el programa de WIFIA que acelera la inversión en la infraestructura de agua de nuestro país proporcionando préstamos a largo plazo y de bajo costo para proyectos considerables a nivel tanto regional como nacional.

  4. Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes

    PubMed Central

    Lu, Fang-Min

    2017-01-01

    Decades ago, it was proposed that Na transport in cardiac myocytes is modulated by large changes in cytoplasmic Na concentration within restricted subsarcolemmal spaces. Here, we probe this hypothesis for Na/K pumps by generating constitutive transsarcolemmal Na flux with the Na channel opener veratridine in whole-cell patch-clamp recordings. Using 25 mM Na in the patch pipette, pump currents decay strongly during continuous activation by extracellular K (τ, ∼2 s). In contradiction to depletion hypotheses, the decay becomes stronger when pump currents are decreased by hyperpolarization. Na channel currents are nearly unchanged by pump activity in these conditions, and conversely, continuous Na currents up to 0.5 nA in magnitude have negligible effects on pump currents. These outcomes are even more pronounced using 50 mM Li as a cytoplasmic Na congener. Thus, the Na/K pump current decay reflects mostly an inactivation mechanism that immobilizes Na/K pump charge movements, not cytoplasmic Na depletion. When channel currents are increased beyond 1 nA, models with unrestricted subsarcolemmal diffusion accurately predict current decay (τ ∼15 s) and reversal potential shifts observed for Na, Li, and K currents through Na channels opened by veratridine, as well as for Na, K, Cs, Li, and Cl currents recorded in nystatin-permeabilized myocytes. Ion concentrations in the pipette tip (i.e., access conductance) track without appreciable delay the current changes caused by sarcolemmal ion flux. Importantly, cytoplasmic mixing volumes, calculated from current decay kinetics, increase and decrease as expected with osmolarity changes (τ >30 s). Na/K pump current run-down over 20 min reflects a failure of pumps to recover from inactivation. Simulations reveal that pump inactivation coupled with Na-activated recovery enhances the rapidity and effectivity of Na homeostasis in cardiac myocytes. In conclusion, an autoregulatory mechanism enhances cardiac Na/K pump activity when

  5. PFOA y PFOS - PREGUNTAS Y RESPUESTAS

    EPA Pesticide Factsheets

    Preguntas y respuestas sobre la decisión de la EPA de publicar avisos de salud sobre el ácido perfluorooctanoico (PFOA) y el sulfonato de perfluorooctano (PFOS) para proporcionar información a los operadores de sistemas de agua potable y funcionarios estat

  6. A importância da poeira e ondas de Alfvén na estabilidade de nuvens moleculares anãs

    NASA Astrophysics Data System (ADS)

    Falceta-Gonçalves, D.; de Juli, M. C.; Jatenco-Pereira, V.

    2003-08-01

    Nuvens moleculares anãs se apresentam dinamicamente estáveis, embora possuam massas muito maiores que a massa de Jeans. Por este motivo, a estabilidade destes objetos não pode ser explicada considerando-se apenas a pressão térmica. Campos magnéticos, aproximadamente uniformes e de ~mG, exercem um termo extra de pressão que sustenta a nuvem, mas somente na direção perpendicular às linhas de campo. Para a direção paralela, ondas de Alfvén geradas por turbulências no meio, por exemplo, têm sido utilizadas. Estas, sendo supostamente fracamente amortecidas, poderiam sustentar a nuvem nesta direção. Entretanto, estes meios contêm grandes quantidades de poeira carregada eletricamente. Estes grãos de poeira possuem frequências cíclotron, que podem entrar em ressonância com as ondas. Neste trabalho calculamos os efeitos que o amortecimento cíclotron da poeira teriam na propagação da onda, e consequentemente na estabilidade da nuvem. Considerando um fluxo de ondas, com um dado espectro de frequências, e uma população de grãos de poeira, com distribuição de tamanho observada, foi possível mostrar que o amortecimento é eficiente em uma larga banda de frequências. Neste caso as ondas seriam rapidamente amortecidas gerando pequenas condensações de alta densidade, e não poderiam ser utilizadas para explicar a estabilidade de uma nuvem inteira. Desta forma, rotação e turbulência seriam candidatos alternativos para garantir a estabilidade destes objetos.

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

    PubMed Central

    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

    2015-01-01

    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+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ 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 Ca2+ 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+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ 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+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field. PMID:25772291

  8. Prevalence and correlates of 'agua celeste' use among female sex workers who inject drugs in Ciudad Juarez, Mexico.

    PubMed

    Morris, Meghan D; Case, Patricia; Robertson, Angela M; Lozada, Remedios; Vera, Alicia; Clapp, John D; Medina-Mora, Maria Elena; Strathdee, Steffanie A

    2011-09-01

    Agua celeste, or "heavenly water", is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of agua celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Between 2008 and 2010, baseline data from FSW-IDUs≥18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14-23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8h per day, and younger age. We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  9. A distribuição de velocidades na linha de visada em galáxias barradas vistas de face

    NASA Astrophysics Data System (ADS)

    Gadotti, D. A.; de Souza, R. E.

    2003-08-01

    Com o objetivo de realizar um estudo cinemático da componente vertical de barras em galáxias, obtivemos espectros de fenda longa de alta razão S/N ao longo dos eixos maior e menor de 14 galáxias barradas vistas de face, nos telescópios de 1.52m do ESO em La Silla, Chile, e de 2.3m do Steward Observatory em Kitt Peak, Arizona. Estes dados nos permitiram determinar a distribuição de velocidades das estrelas ao longo do eixo vertical das barras e discos destes sistemas, tanto no centro como em pontos que distam cerca de 5 e 20 segundos de arco do núcleo, correspondendo a distâncias de cerca de 0.7 e 2.8 kpc, respectivamente. Desta forma, a variação radial da distribuição de velocidades também pôde ser avaliada. Este tipo de análise tem raros exemplos na literatura por ser caro em termos de tempo de telescópio. Entretanto, é de fácil justificativa, considerando que traz novas informações que podem ser utilizadas para aperfeiçoar modelos teóricos acerca da formação e evolução de galáxias. Um algoritmo por nós desenvolvido foi utilizado para obter as distribuições de velocidades como Gaussianas generalizadas (polinômios de Gauss-Hermite), o que traz um ingrediente a mais neste tipo de estudo que, tradicionalmente, se utiliza de Gaussianas puras, uma hipótese nem sempre razoável. Apresentaremos os resultados deste trabalho, que incluem um diagnóstico para a identificação de barras recém formadas, e testes para o modelo isotérmico de discos. Mostraremos que: (i) a escolha das estrelas padrão em velocidade, e dos parâmetros da Gaussiana, deve ser muito bem justificada já que tem influência significativa nos resultados; (ii) muitas galáxias apresentam uma depressão na dispersão de velocidades na região central, que pode estar associada a um disco interno; e (iii) a dispersão de velocidades é constante ao longo da barra, nos eixos maior e menor, mas cai substancialmente quando se passa da barra para o disco.

  10. A Wind-Forced Modeling Study of the Canary Current System from 30 Degrees N to 42.5 Degrees N

    DTIC Science & Technology

    1998-06-01

    and Haynes and Barton (1990), using high resolution infra-red images from NOAA7 and NOAA9 and numerous in- situ measurements, reveal the existence of...dinamica das Aguas costeiras de Portugal. Dissertacao apresentada a Universidade de Lisboa para obtencao do grau de Doutor em Fisica, especializacao

  11. Comparação de modelos para o cálculo de perturbações orbitais devidas à maré terrestre

    NASA Astrophysics Data System (ADS)

    Vieira Pinto, J.; Vilhena de Moraes, R.

    2003-08-01

    Aplicações recentes de satélites artificiais com finalidades geodinâmicas requerem órbitas determinadas com bastante precisão. Em particular marés terrestres influenciam o potencial terrestre causando perturbações adicionais no movimento de satélites artificiais, as quais tem sido medidas por diversos processos. A atração exercida pela lua e pelo sol sobre a terra produz deslocamentos elásticos em seu interior e uma protuberância em sua superfície. O resultado é uma pequena variação na distribuição da massa na terra, consequentemente no geopotencial. As perturbações nos elementos orbitais de satélites artificiais terrestres devidas a maré terrestre podem ser estudadas a partir das equações de Lagrange, considerando-se um conveniente potencial. Por outro lado, como tem sido feito pelo IERS, as mudanças induzidas pela maré terrestre no geopotencial podem ser convenientemente modeladas como variações nos coeficientes Cnm e Snm do geopotencial. As duas teorias ainda não foram comparados para um mesmo satélite. Neste trabalho são apresentadas e comparadas as variações de longo período e seculares nas perturbações orbitais devidas à maré terrestre, calculadas por um modelo simples, o de Kozai, e pelo modelo do IERS. Resultados preliminares mostram, para os satélites SCD2 e CBERS1, e para a Lua em movimento elíptico e precessionando, as perturbações seculares no argumento do perigeu e na longitude do nodo ascendente.

  12. A remarkably stable TipE gene cluster: evolution of insect Para sodium channel auxiliary subunits

    PubMed Central

    2011-01-01

    Background First identified in fruit flies with temperature-sensitive paralysis phenotypes, the Drosophila melanogaster TipE locus encodes four voltage-gated sodium (NaV) channel auxiliary subunits. This cluster of TipE-like genes on chromosome 3L, and a fifth family member on chromosome 3R, are important for the optional expression and functionality of the Para NaV channel but appear quite distinct from auxiliary subunits in vertebrates. Here, we exploited available arthropod genomic resources to trace the origin of TipE-like genes by mapping their evolutionary histories and examining their genomic architectures. Results We identified a remarkably conserved synteny block of TipE-like orthologues with well-maintained local gene arrangements from 21 insect species. Homologues in the water flea, Daphnia pulex, suggest an ancestral pancrustacean repertoire of four TipE-like genes; a subsequent gene duplication may have generated functional redundancy allowing gene losses in the silk moth and mosquitoes. Intronic nesting of the insect TipE gene cluster probably occurred following the divergence from crustaceans, but in the flour beetle and silk moth genomes the clusters apparently escaped from nesting. Across Pancrustacea, TipE gene family members have experienced intronic nesting, escape from nesting, retrotransposition, translocation, and gene loss events while generally maintaining their local gene neighbourhoods. D. melanogaster TipE-like genes exhibit coordinated spatial and temporal regulation of expression distinct from their host gene but well-correlated with their regulatory target, the Para NaV channel, suggesting that functional constraints may preserve the TipE gene cluster. We identified homology between TipE-like NaV channel regulators and vertebrate Slo-beta auxiliary subunits of big-conductance calcium-activated potassium (BKCa) channels, which suggests that ion channel regulatory partners have evolved distinct lineage-specific characteristics

  13. Wind-Forced Modeling Studies of Currents, Meanders, Eddies, and Filaments of the Canary Current System

    DTIC Science & Technology

    1997-06-01

    infra-red images from NOAA7 and NOAA9 and numerous in- situ measurements reveal the existence of a surface poleward flow off the northern coast of...dinamica das Aguas costeiras de Portugal. Dissertacao apresentada a Universidade de Lisboa para obtencao do grau de Doutor em Fisica, especializacao

  14. Introduction of a Simple Experiment for the Undergraduate Organic Chemistry Laboratory Demonstrating the Lewis Acid and Shape-Selective Properties of Zeolite Na-Y

    ERIC Educational Resources Information Center

    Maloney, Vincent; Szczepanski, Zach

    2017-01-01

    A simple, inexpensive, discovery-based experiment for undergraduate organic laboratories has been developed that demonstrates the Lewis acid and shape-selective properties of zeolites. Calcined zeolite Na-Y promotes the electrophilic aromatic bromination of toluene with a significantly higher para/ortho ratio than observed under conventional…

  15. Acidosis Differentially Modulates Inactivation in NaV1.2, NaV1.4, and NaV1.5 Channels

    PubMed Central

    Vilin, Yury Y.; Peters, Colin H.; Ruben, Peter C.

    2012-01-01

    NaV channels play a crucial role in neuronal and muscle excitability. Using whole-cell recordings we studied effects of low extracellular pH on the biophysical properties of NaV1.2, NaV1.4, and NaV1.5, expressed in cultured mammalian cells. Low pH produced different effects on different channel subtypes. Whereas NaV1.4 exhibited very low sensitivity to acidosis, primarily limited to partial block of macroscopic currents, the effects of low pH on gating in NaV1.2 and NaV1.5 were profound. In NaV1.2 low pH reduced apparent valence of steady-state fast inactivation, shifted the τ(V) to depolarizing potentials and decreased channels availability during onset to slow and use-dependent inactivation (UDI). In contrast, low pH delayed open-state inactivation in NaV1.5, right-shifted the voltage-dependence of window current, and increased channel availability during onset to slow and UDI. These results suggest that protons affect channel availability in an isoform-specific manner. A computer model incorporating these results demonstrates their effects on membrane excitability. PMID:22701426

  16. Prevalence and Correlates of ‘Agua Celeste’ Use among Female Sex Workers who Inject Drugs in Ciudad Juarez, Mexico

    PubMed Central

    Morris, Meghan D.; Case, Patricia; Robertson, Angela M.; Lozada, Remedios; Vera, Alicia; Clapp, John D.; Medina-Mora, Maria Elena; Strathdee, Steffanie A.

    2011-01-01

    Background Agua celeste, or “heavenly water,” is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of Agua Celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Methods Between 2008 and 2010, baseline data from FSW-IDUs ≥ 18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Results Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14–23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8 hours per day, and younger age. Discussion We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. PMID:21441001

  17. Geochemistry of thermal fluids in NW Honduras: New perspectives for exploitation of geothermal areas in the southern Sula graben

    NASA Astrophysics Data System (ADS)

    Capaccioni, Bruno; Franco, Tassi; Alberto, Renzulli; Orlando, Vaselli; Marco, Menichetti; Salvatore, Inguaggiato

    2014-06-01

    The results of a geochemical survey on thermal waters and, for the first time for this site, gas discharges in five geothermal sites (Azacualpa "La Cueva", Río Ulua, Río Gualcarque, El Olivar and Laguna de Agua Caliente) in NW Honduras are here presented and discussed. El Olivar and Laguna de Agua Caliente, in the southern part of the Sula graben are very close to a Quaternary basaltic field, whereas Azacualpa "La Cueva", Río Ulua and Río Gualcarque, located to the southwest of the Yojoa Lake, direcly emerge from the Cretaceous limestone deposits. The measured temperatures range between 37.5 and 104.8 °C. "Mature", alkaline, Na-SO4 thermal waters discharge from Azacualpa "La Cueva", while those from El Olivar and Laguna de Agua Caliente are "immature" and show a Na-HCO3 composition. Chemical equilibria of waters and gases from the Azacualpa "La Cueva" thermal springs indicate temperatures ranging from 150 to 200 °C. Conversely, gas discharges from El Olivar and Laguna de Agua Caliente have attained a partial chemical equilibrium in the liquid phase at slightly higher temperatures (200-250 °C), although gas-gas faster reactions involving CO seem to be adjusted in an isothermally separated vapor phase. Unlike Azacualpa, SiO2 geothermometer at El Olivar and Laguna de Agua Caliente indicates equilibrium temperatures for the liquid phase much lower than those calculated for the gas phase (≤ 120 °C). We conclude that thermal waters from the Azacualpa area likely represent the direct emergence of a water dominated reservoir having temperatures ≤ 150-200 °C. By contrast, at El Olivar and Laguna de Agua Caliente hot springs are supplied by a boiling shallow aquifer fed by a vapor phase rising from a steam-dominated zone. The above geochemical model is consistent with a geothermal reservoir hosted within the Cretaceous carbonate sequences of the Yojoa Group in the whole investigated sites. The reservoir extensively crops out in the Azacualpa area whereas the

  18. Degradación de Marismas Costera: el Impacto de la Eutrofización en la Supervivencia del las Marismas Costeras en New England y Central California, USA. (Salt Marsh Deterioration in New England and Central California: Impacts of Eutrophication on Salt Marsh Survival.)

    EPA Science Inventory

    Las marismas costeras proporcionan numerosos beneficios a los ecosistemas, incluyendo la proporción del hábitat de la flora y fauna, la protección de las zonas costeras contra inundaciones durante eventos extremos, mejoran la calidad del agua para las almejas y ostras a través de...

  19. Urbanization and the groundwater budget, metropolitan Seoul area, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Yoon-Young; Lee, Kang-Kun; Sung, Ig Hwan

    2001-07-01

    du métro et les pompages privés. Le bilan entre la recharge de la nappe et sa décharge est proche de l'équilibre. Cependant, les infiltrations d'eaux usées, les décharges abandonnées, les décharges d'ordures et les puits abandonnés portent atteinte à la qualité de l'eau souterraine et à la capacité de contrôler les flux de contaminants. Resumen. La ciudad de Seúl tiene más de 10 millones de habitantes en un área de 605 km2. Se bombea aguas subterráneas para abastecimiento urbano y para usos industriales, así como para el drenaje de instalaciones subterráneas y de solares en construcción. Aunque la mayor parte del agua de boca procede del río Han, los ciudadanos de Seúl están muy concienciados por la cantidad y calidad de las aguas subterráneas, ya que su explotación para uso de boca está experimentando un continuo incremento. El presente estudio identifica los factores que más afectan a la calidad de las aguas subterráneas en el área de Seúl y hace una estimación del balance de agua en el territorio urbano. Entre los factores principales que afectan al balance y a la calidad de las aguas subterráneas, se incluye el lixiviado de la red municipal de suministro y de la red de alcantarillado, la infiltración de agua de lluvia, las fluctuaciones del nivel del río Han, el sistema de bombeo del metro y los bombeos domésticos. El balance entre la recarga y la descarga en el acuífero está próximo al equilibrio. Sin embargo, la calidad de las aguas subterráneas y la capacidad de controlar los flujos de contaminación están amenazadas por la infiltración de aguas residuales, vertederos abandonados, depósitos de residuos y pozos abanadonados.

  20. Role of Na+ conductance, Na+-H+ exchange, and Na+-K+-2Cl− symport in the regulatory volume increase of rat hepatocytes

    PubMed Central

    Wehner, Frank; Tinel, Hanna

    1998-01-01

    In rat hepatocytes under hypertonic stress, the entry of Na+ (which is thereafter exchanged for K+ via Na+-K+-ATPase) plays the key role in regulatory volume increase (RVI).In the present study, the contributions of Na+ conductance, Na+-H+ exchange and Na+-K+-2Cl− symport to this process were quantified in confluent primary cultures by means of intracellular microelectrodes and cable analysis, microfluorometric determinations of cell pH and buffer capacity, and measurements of frusemide (furosemide)/bumetanide-sensitive 86Rb+ uptake, respectively. Osmolarity was increased from 300 to 400 mosmol l−1 by addition of sucrose.The experiments indicate a relative contribution of approximately 4:1:1 to hypertonicity-induced Na+ entry for the above-mentioned transporters and the overall Na+ yield equalled 51 mmol l−1 (10 min)−1.This Na+ gain is in good agreement with the stimulation of Na+ extrusion via Na+-K+-ATPase plus the actual increase in cell Na+, namely 55 mmol l−1 (10 min)−1, as was determined on the basis of ouabain-sensitive 86Rb+ uptake and by means of Na+-sensitive microelectrodes, respectively.The overall increase in Na+ and K+ activity plus the expected concomitant increase in cell Cl− equalled 68 mmol l−1, which fits well with the increase in osmotic activity expected to occur from an initial cell shrinkage to 87.5 % and a RVI to 92.6 % of control, namely 53 mosmol l−1.The prominent role of Na+ conductance in the RVI of rat hepatocytes could be confirmed on the basis of the pharmacological profile of this process, which was characterized by means of confocal laser-scanning microscopy. PMID:9481677

  1. Geology and geochemistry of Pelagatos, Cerro del Agua, and Dos Cerros monogenetic volcanoes in the Sierra Chichinautzin Volcanic Field, south of México City

    NASA Astrophysics Data System (ADS)

    Agustín-Flores, Javier; Siebe, Claus; Guilbaud, Marie-Noëlle

    2011-04-01

    This study focuses on the geology and geochemistry of three closely-spaced monogenetic volcanoes that are located in the NE sector of the Sierra Chichinautzin Volcanic Field near México City. Pelagatos (3020 m.a.s.l.) is a small scoria cone (0.0017 km 3) with lava flows (0.036 km 3) that covered an area of 4.9 km 2. Cerro del Agua scoria cone (3480 m.a.s.l., 0.028 km 3) produced several lava flows (0.24 km 3) covering an area of 17.6 km 2. Dos Cerros is a lava shield which covers an area of 80.3 km 2 and is crowned by two scoria cones: Tezpomayo (3080 m.a.s.l., 0.022 km 3) and La Ninfa (3000 m.a.s.l., 0.032 km 3). The eruptions of Cerro del Agua and Pelagatos occurred between 2500 and 14,000 yr BP. The Dos Cerros eruption took place close to 14,000 yr BP as constrained by radiocarbon dating. Rocks from these three volcanoes are olivine-hypersthene normative basaltic andesites and andesites with porphyritic, aphanitic, and glomeroporphyritic textures. Their mineral assemblages include olivine, clinopyroxene, and orthopyroxene phenocrysts (≤ 10 vol.%) embedded in a trachytic groundmass which consists mainly of plagioclase microlites and glass. Pelagatos rocks also present quartz xenocrysts. Due to their high Cr and Ni contents, and high Mg#s, Pelagatos rocks are considered to be derived from primitive magmas, hence the importance of this volcano for understanding petrogenetic processes in this region. Major and trace element abundances and petrography of products from these volcanoes indicate a certain degree of crystal fractionation during ascent to the surface. However, the magmas that formed the volcanoes evolved independently from each other and are not cogenetically related. REE, HFSE, LILE, and isotopic (Sr, Nd, and Pb) compositions point towards a heterogeneous mantle source that has been metasomatized by aqueous/melt phases from the subducted Cocos slab. There is no clear evidence of important crustal contributions in the compositions of Pelagatos and

  2. Kinetic contribution to extracellular Na+/K+ selectivity in the Na+/K+ pump.

    PubMed

    Vleeskens, Elizabeth; Clarke, Ronald J

    2018-05-01

    The sodium potassium pump (Na + ,K + -ATPase) shows a high selectivity for K + over Na + binding from the extracellular medium. To understand the K + selectivity in the presence of a high concentration of competing Na + ions requires consideration of more than just ion binding affinities. Here, equilibrium-based calculations of the extracellular occupation of the Na + ,K + -ATPase transport sites by Na + and K + are compared to fluxes through Na + and K + transport pathways. The results show that, under physiological conditions, there is a 332-fold selectivity for pumping of K + from the extracellular medium into the cytoplasm relative to Na + , whereas equilibrium calculations alone predict only a 7.5-fold selectivity for K + . Thus, kinetic effects make a major contribution to the determination of extracellular K + selectivity.

  3. Avaliação dos efeitos do subgalato de bismuto na proliferação de miofibroblastos

    PubMed Central

    de Lima, Rubianne Ligório; Sampaio, Cláudia Paraguaçu; Seidel, Karin Caroline; Branco, Melina; Sobreiro, Rafaela Mabile

    2016-01-01

    Resumo Contexto O subgalato de bismuto é um metal pesado e insolúvel, utilizado por suas propriedades adstringentes e hemostáticas. Objetivo Avaliar os efeitos do subgalato de bismuto na cicatrização mediante observação de miofibroblastos em pele de ratos. Métodos Foram utilizados 60 ratos da linhagem Wistar, que receberam uma ferida no dorso da pele. Os animais foram divididos em dois grupos: controle (aplicação diária de cloreto de sódio a 0,9%) e experimental (aplicação diária de 0,5 mg de subgalato de bismuto). Cada grupo foi subdividido em três subgrupos, que foram reoperados para retirada da ferida em 3, 7 e 14 dias. Foi realizada coloração de hematoxilina eosina, picrosirius e imuno-histoquímica para avaliar contagem de miofibroblastos, resposta inflamatória e síntese de colágeno. Resultados Não foi encontrada diferença entre os grupos controle e experimento com relação ao processo inflamatório – subgrupos 3 dias (p = 1), 7 dias (p = 0,474) e 14 dias (p = 303). A avaliação dos colágenos tipo I e III no grupo-controle não demonstrou benefícios de cicatrização – 3 dias (p = 0,436), 7 dias (p = 0,853) e 14 dias (p = 0,436); já no grupo experimental, houve aumento dos colágenos tipos I e III nos subgrupos 3 e 14 dias (p = 0,005). A imuno-histoquímica confirmou os resultados encontrados na coloração hematoxilina eosina, na qual a área de miofibroblastos entre os subgrupos, nos grupos experimental (p = 0,4) e controle (p = 0,336), foi indiferente. Conclusão A utilização do subgalato de bismuto em ferida de pele de ratos não evidenciou benefícios na cicatrização, ou seja, não houve diferença na fibroplasia quando comparados os grupos experimental e controle. PMID:29930592

  4. Questões mais freqüentes na área de astronomia

    NASA Astrophysics Data System (ADS)

    Segundo, H. A. S.; Garcia, G. C.; Caretta, C. A.; Lima, F. P.

    2003-08-01

    É amplamente reconhecido que as pessoas em geral têm grande fascínio e interesse pela Astronomia. Por outro lado, o conteúdo dessa área incluído no ensino formal está longe de ser abrangente e suficiente para suprir a demanda. Esse interesse permite otimizar a divulgação e o ensino não formal de Astronomia aliando a adequação do conteúdo à expectativa das pessoas. Nesse intuito, nosso trabalho busca mapear que assuntos da Astronomia despertam mais a atenção e o interesse das pessoas e o quanto disso é estimulado pela mídia, que freqüentemente aproveita-se desse interesse de forma sensacionalista, trazendo contribuições positivas e negativas. Para esta avaliação, utilizamos as pesquisas específicas e de caracterização do público que freqüentou o MAst nos anos de 2001 a 2003, pesquisa das matérias de Astronomia veiculadas na mídia escrita da cidade do Rio de Janeiro no mesmo período, além da base de dados do programa Pergunte a um astrônomo, realizado no Observatório Nacional nos anos de 1997 a 1999. Para a análise dos dados, dividimos as perguntas em dez categorias, cada uma com suas subcategorias, tomando como referência as divisões, comissões e grupos de trabalho da IAU. Apresentamos neste trabalho os resultados dessa pesquisa, que incluem, entre outros, a predominância de questões nas categorias Observação do Céu e Sistemas Planetários enquanto nos jornais dominam as notícias de Sistemas Planetários e Espaço & Astronáutica. Outro resultado interessante indicou que as dúvidas de crianças do ensino fundamental se concentram em algumas categorias enquanto as questões de adultos são mais distribuídas por todas as categorias. Os resultados dessa pesquisa serão aplicados diretamente no aperfeiçoamento das atividades do Programa de Observação de Céu, bem como na elaboração de novos projetos e eventos realizados no MAst.

  5. Mineralogy, structural control and age of the Incachule Sb epithermal veins, the Cerro Aguas Calientes collapse caldera, Central Puna

    NASA Astrophysics Data System (ADS)

    Salado Paz, Natalia; Petrinovic, Iván; Do Campo, Margarita; Brod, José Affonso; Nieto, Fernando; da Silva Souza, Valmir; Wemmer, Klauss; Payrola, Patricio; Ventura, Roberto

    2018-03-01

    The Incachule Sb epithermal veins is located near to the N-E rim of the Cerro Aguas Calientes collapse caldera (17.5-10.8 Ma), in the geologic province of Puna, Salta- Argentina. It is hosted in Miocene felsic volcanic rocks with continental arc signature. The district includes twelve vein systems with mineralization of Sb occurring in hydrothermal breccias and stockwork. The veins are composed of quartz-sulfide with pyrite, stibnite and arsenopyrite. All around the veins, wall rocks are variably altered to clay minerals and sulfates in an area of around 2.5 km wide by more than 7 km long. The hydrothermal alterations recognized are: silicic, phyllic and argillic. The veins are characterized by high contents of Sb, As, and Tl and intermediate contents of Pb-Zn-Cu, and traces of Ag and Au. Homogenization and ice-melting temperatures of fluid inclusions vary from 125 °C to 189 °C and -2.4 °C to -0.8 °C. The isotopic data indicated a range of δ34S -3.04‰ to +0.72‰ consistent with a magmatic source for sulfur. We present the firsts K-Ar ages for hydrothermal illite/smectite mixed layers (I/SR1, 60% illite layers) and illite that constrain the age of the ore deposit (8.5-6.7 ± 0.2 Ma). The data shown here, let characterized the Incachule district as a shallow low sulfidation epithermal system hosted in a collapse caldera. Our data also indicate that mineralization is structurally controlled by a fault system related to the 10.3 Ma collapse of Aguas Calientes caldera. The interpreted local stress field is consistent with the regional one.

  6. Um supressor de fundo térmico para a câmara infravermelha CamIV

    NASA Astrophysics Data System (ADS)

    Jablonski, F.; Laporte, R.

    2003-08-01

    O ângulo sólido subtendido pelos pixels na câmara infravermelha do NexGal (CamIV) que operamos no OPD/LNA contém contribuições provenientes do sistema de coleta de fluxo propriamente dito - sendo esta a parte que interessa para as medidas astronômicas - e contribuições da obstrução central, sistema de suporte do espelho secundário e região exterior à pupila de entrada do telescópio. Estas últimas contribuições são devi-das à emissão de corpo negro à temperatura ambiente e aumentam exponencialmente para comprimentos de onda maiores que 2 micra (banda K, no infravermelho próximo). Embora a resultante pode ser quantificada e subtraída dos sinais relevantes, sua variância se adiciona à variância do sinal, e pode ser facilmente a contribuição domi-nante para a incerteza final das medidas, tornando ineficiente o processo de extração de informação e degradando a sensibilidade da câmara. A maneira clássica de resolver esse problema em sistemas ópticos que operam no infravermelho, onde os efeitos da emissão térmica do ambiente são importantes, é restringir o ângulo sólido subtendido pelos pixels individuais exclusivamente aos raios provenientes do sistema óptico. Para tanto, projeta-se uma imagem real, bastante reduzida, da pupila de entrada do sistema óptico num anteparo que transmita para o sistema de imageamento só o que interessa, bloqueando as contribuições das bordas externas à pupila de entrada, obstrução central do telescópio e sistema de suporte. Como a projeção é realizada em ambiente criogênico, a contribuição térmica espúria é efetivamente eliminada. Nós optamos por um sistema do tipo Offner para implementar na prática esta função. Trata-se de um sistema baseado em espelhos esféricos, bastante compacto e ajustado por construção. A opção por espelhos do mesmo material que o sistema de suporte (Alumínio) minimiza a dilatação diferencial, crítica nesse tipo de aplicação. Apresentamos as solu

  7. Na and K Dependence of the Na/K Pump in Cystic Fibrosis Fibroblasts

    NASA Astrophysics Data System (ADS)

    Reznik, Vivian M.; Schneider, Jerry A.; Mendoza, Stanley A.

    1981-11-01

    The Na and K dependence of the Na/K pump was measured in skin fibroblasts from patients with cystic fibrosis and age/sex-matched controls. Under basal conditions, there was no difference between control and cystic fibrosis cells in protein per cell, intracellular Na and K content, or Na/K pump activity (measured as ouabain-sensitive 86Rb uptake). There was no difference in the Na dependence of the Na/K pump between cystic fibrosis cells and control cells. In cells from patients with cystic fibrosis, the Na/K pump had a significantly lower affinity for K (Km = 1.6 mM) when compared to normals (Km = 0.9 mM). This difference was demonstrated by using two independent experimental designs.

  8. Código para imageamento indireto de estrelas em sistemas binarios: simulação de variações elipsoidais e do perfil das linhas

    NASA Astrophysics Data System (ADS)

    Souza, T. R.; Baptista, R.

    2003-08-01

    As estrelas secundárias em variáveis cataclí smicas (VCs) e binárias-x de baixa massa (BXBMs) são cruciais para o entendimento da origem, evolução e comportamento destas binárias interagentes. Elas são estrelas magneticamente ativas submetidas a condições ambientais extremas [e.g., estão muito próximas de uma fonte quente e irradiante; têm rotação extremamente rápida e forma distorcida; estão perdendo massa a taxas de 10-8-10-10 M¤/ano] que contribuem para que suas propriedades sejam distintas das de estrelas de mesma massa na seqüência principal. Por outro lado, o padrão de irradiação na face da secundária fornece informação sobre a geometria das estruturas de acréscimo em torno da estrela primária. Assim, a obtenção de imagens da superfície destas estrelas é de grande interesse astrofísico. A Tomografia Roche usa as variações no perfil das linhas de emissão/absorção da estrela secundária em função da fase orbital para mapear a distribuição de brilho em sua superfície. Neste trabalho apresentamos os resultados iniciais do desenvolvimento de um programa para o mapeamento da distribuição de brilho na superfí cie das estrelas secundárias em VCs e BXBMs com técnicas de astro-tomografia. Presentemente temos em operação um código que simula as variações no perfil das linhas em conseqüência de efeito Doppler resultante da combinação de rotação e translação de uma estrela em forma de lobo de Roche em torno do centro de massa da binária, em função da distribuição de brilho na superfície desta estrela. O código igualmente produz a curva de luz resultante das variações de aspecto da estrela em função da fase orbital (variações elipsoidais).

  9. Response of saliva Na/K ratio to changing Na supply of lactating cows under tropical conditions.

    PubMed

    Thiangtum, Wandee; Schonewille, J Thomas; Verstegen, Martin Wa; Arsawakulsudhi, Supot; Rukkwamsuk, Theera; Hendriks, Wouter H

    2017-06-01

    Factorial determination of the sodium (Na) requirement of heat-stressed lactating cows is hindered by accurate estimates of the Na losses through sweat. Direct studies, therefore, may be needed requiring information on the time course of healthy animals to become Na depleted and the subsequent rate of repletion. The rate of Na depletion and subsequent rate of Na repletion with two levels of dietary Na to lactating dairy cows housed under tropical conditions were investigated using the salivary Na/K. The 12 lactating cows (salivary Na/K ratio 14.6) rapidly developed clinical signs of Na deficiency, including pica, polyuria and polydipsia, reduced body weight and reduced milk yield when fed a low-Na ration (0.33 g kg -1 dry matter (DM)) for 3 weeks. Deficiency symptoms were associated with a rapid decrease in salivary Na/K ratio to <4.3 from 7 to 21 days. Subsequent repletion of the cows with NaCl to a ration concentration of 1.1 or 1.6 g Na kg -1 DM for 5 weeks did not restore salivary Na/K ratio to values of >6. A daily Na intake of heat-stressed lactating cows to a ration intake of 1.6 g Na kg -1 DM was insufficient to restore Na deficiency. One week was sufficient to deplete heat-stressed lactating cows of Na, allowing for rapid dose-response studies utilizing the salivary Na/K ratio as a parameter for Na status of cows under tropical conditions. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  10. Drosophila as a model for epilepsy: bss is a gain-of-function mutation in the para sodium channel gene that leads to seizures.

    PubMed

    Parker, Louise; Padilla, Miguel; Du, Yuzhe; Dong, Ke; Tanouye, Mark A

    2011-02-01

    We report the identification of bang senseless (bss), a Drosophila melanogaster mutant exhibiting seizure-like behaviors, as an allele of the paralytic (para) voltage-gated Na(+) (Na(V)) channel gene. Mutants are more prone to seizure episodes than normal flies because of a lowered seizure threshold. The bss phenotypes are due to a missense mutation in a segment previously implicated in inactivation, termed the "paddle motif" of the Na(V) fourth homology domain. Heterologous expression of cDNAs containing the bss(1) lesion, followed by electrophysiology, shows that mutant channels display altered voltage dependence of inactivation compared to wild type. The phenotypes of bss are the most severe of the bang-sensitive mutants in Drosophila and can be ameliorated, but not suppressed, by treatment with anti-epileptic drugs. As such, bss-associated seizures resemble those of pharmacologically resistant epilepsies caused by mutation of the human Na(V) SCN1A, such as severe myoclonic epilepsy in infants or intractable childhood epilepsy with generalized tonic-clonic seizures.

  11. Glutathionylation-Dependence of Na(+)-K(+)-Pump Currents Can Mimic Reduced Subsarcolemmal Na(+) Diffusion.

    PubMed

    Garcia, Alvaro; Liu, Chia-Chi; Cornelius, Flemming; Clarke, Ronald J; Rasmussen, Helge H

    2016-03-08

    The existence of a subsarcolemmal space with restricted diffusion for Na(+) in cardiac myocytes has been inferred from a transient peak electrogenic Na(+)-K(+) pump current beyond steady state on reexposure of myocytes to K(+) after a period of exposure to K(+)-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na(+) that accumulated in the diffusion-restricted space during pump inhibition in K(+)-free extracellular solution. However, there are no known physical barriers that account for such restricted Na(+) diffusion, and we examined if changes of activity of the Na(+)-K(+) pump itself cause the transient peak current. Reexposure to K(+) reproduced a transient current beyond steady state in voltage-clamped ventricular myocytes as reported by others. Persistence of it when the Na(+) concentration in patch pipette solutions perfusing the intracellular compartment was high and elimination of it with K(+)-free pipette solution could not be reconciled with restricted subsarcolemmal Na(+) diffusion. The pattern of the transient current early after pump activation was dependent on transmembrane Na(+)- and K(+) concentration gradients suggesting the currents were related to the conformational poise imposed on the pump. We examined if the currents might be accounted for by changes in glutathionylation of the β1 Na(+)-K(+) pump subunit, a reversible oxidative modification that inhibits the pump. Susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na(+)-K(+) pump, and glutathionylation with the pump stabilized in conformations equivalent to those expected to be imposed on voltage-clamped myocytes supported this hypothesis. So did elimination of the transient K(+)-induced peak Na(+)-K(+) pump current when we included glutaredoxin 1 in patch pipette solutions to reverse glutathionylation. We conclude that transient K(+)-induced peak Na(+)-K(+) pump current reflects the effect

  12. Glutathionylation-Dependence of Na+-K+-Pump Currents Can Mimic Reduced Subsarcolemmal Na+ Diffusion

    PubMed Central

    Garcia, Alvaro; Liu, Chia-Chi; Cornelius, Flemming; Clarke, Ronald J.; Rasmussen, Helge H.

    2016-01-01

    The existence of a subsarcolemmal space with restricted diffusion for Na+ in cardiac myocytes has been inferred from a transient peak electrogenic Na+-K+ pump current beyond steady state on reexposure of myocytes to K+ after a period of exposure to K+-free extracellular solution. The transient peak current is attributed to enhanced electrogenic pumping of Na+ that accumulated in the diffusion-restricted space during pump inhibition in K+-free extracellular solution. However, there are no known physical barriers that account for such restricted Na+ diffusion, and we examined if changes of activity of the Na+-K+ pump itself cause the transient peak current. Reexposure to K+ reproduced a transient current beyond steady state in voltage-clamped ventricular myocytes as reported by others. Persistence of it when the Na+ concentration in patch pipette solutions perfusing the intracellular compartment was high and elimination of it with K+-free pipette solution could not be reconciled with restricted subsarcolemmal Na+ diffusion. The pattern of the transient current early after pump activation was dependent on transmembrane Na+- and K+ concentration gradients suggesting the currents were related to the conformational poise imposed on the pump. We examined if the currents might be accounted for by changes in glutathionylation of the β1 Na+-K+ pump subunit, a reversible oxidative modification that inhibits the pump. Susceptibility of the β1 subunit to glutathionylation depends on the conformational poise of the Na+-K+ pump, and glutathionylation with the pump stabilized in conformations equivalent to those expected to be imposed on voltage-clamped myocytes supported this hypothesis. So did elimination of the transient K+-induced peak Na+-K+ pump current when we included glutaredoxin 1 in patch pipette solutions to reverse glutathionylation. We conclude that transient K+-induced peak Na+-K+ pump current reflects the effect of conformation-dependent β1 pump subunit

  13. Generating para-water from para-hydrogen: A Gedankenexperiment.

    PubMed

    Ivanov, Konstantin L; Bodenhausen, Geoffrey

    2018-07-01

    A novel conceptual approach is described that is based on the transfer of hyperpolarization from para-hydrogen in view of generating a population imbalance between the two spin isomers of H 2 O. The approach is analogous to SABRE (Signal Amplification By Reversible Exchange) and makes use of the transfer of spin order from para-hydrogen to H 2 O in a hypothetical organometallic complex. The spin order transfer is expected to be most efficient at avoided level crossings. The highest achievable enrichment levels of para- and ortho-water are discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Cytosolic Na+ Controls an Epithelial Na+ Channel Via the Go Guanine Nucleotide-Binding Regulatory Protein

    NASA Astrophysics Data System (ADS)

    Komwatana, P.; Dinudom, A.; Young, J. A.; Cook, D. I.

    1996-07-01

    In tight Na+-absorbing epithelial cells, the rate of Na+ entry through amiloride-sensitive apical membrane Na+ channels is matched to basolateral Na+ extrusion so that cell Na+ concentration and volume remain steady. Control of this process by regulation of apical Na+ channels has been attributed to changes in cytosolic Ca2+ concentration or pH, secondary to changes in cytosolic Na+ concentration, although cytosolic Cl- seems also to be involved. Using mouse mandibular gland duct cells, we now demonstrate that increasing cytosolic Na+ concentration inhibits apical Na+ channels independent of changes in cytosolic Ca2+, pH, or Cl-, and the effect is blocked by GDP-β -S, pertussis toxin, and antibodies against the α -subunits of guanine nucleotide-binding regulatory proteins (Go). In contrast, the inhibitory effect of cytosolic anions is blocked by antibodies to inhibitory guanine nucleotide-binding regulatory proteins (Gi1/Gi2. It thus appears that apical Na+ channels are regulated by Go and Gi proteins, the activities of which are controlled, respectively, by cytosolic Na+ and Cl-.

  15. Managing for sustainability in an arid climate: lessons learned from 20 years of groundwater management in Arizona, USA

    NASA Astrophysics Data System (ADS)

    Jacobs, Katharine L.; Holway, James M.

    'importance de données de haute qualité dans la prise de décisions de gestion. Resumen Se ha logrado un progreso substancial en el centro de Arizona para conseguir un futuro más sustentable del agua, particularmente al trasladar la demanda urbana desde un suministro basado principalmente en aguas subterráneas no renovables hacia una mayor dependencia de las aguas superficiales de los ríos Colorado y Salado y de los efluentes de aguas depuradas. Los esfuerzos de gestión incluyen un amplio rango de programas legales y voluntarios que han tenido un éxito combinado. El Departamento de Recursos Hídricos ha aprendido diversas lecciones clave a lo largo de los años, y este artículo intenta establecer el contexto de la gestión del agua e identificar lo averiguado para beneficio de terceros que quieran evaluar enfoques alternativos para gestionar las aguas subterráneas. Entre los temas tratados, destaca la evaluación de los enfoques de gestión del agua en un contexto político público, la efectividad de enfoques alternativos de gestión y los méritos relativos de los esfuerzos regulativos y no regulativos, y la importancia de los datos de alta calidad para la toma de decisiones de gestión. Groundwater use in many areas of Arizona greatly exceeds the natural replenishment of the aquifer, so although a portion of the groundwater use is renewable, the majority is not.

  16. Agua Caliente Wind/Solar Project at Whitewater Ranch

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hooks, Todd; Stewart, Royce

    2014-12-16

    Agua Caliente Band of Cahuilla Indians (ACBCI) was awarded a grant by the Department of Energy (DOE) to study the feasibility of a wind and/or solar renewable energy project at the Whitewater Ranch (WWR) property of ACBCI. Red Mountain Energy Partners (RMEP) was engaged to conduct the study. The ACBCI tribal lands in the Coachella Valley have very rich renewable energy resources. The tribe has undertaken several studies to more fully understand the options available to them if they were to move forward with one or more renewable energy projects. With respect to the resources, the WWR property clearly hasmore » excellent wind and solar resources. The DOE National Renewable Energy Laboratory (NREL) has continued to upgrade and refine their library of resource maps. The newer, more precise maps quantify the resources as among the best in the world. The wind and solar technology available for deployment is also being improved. Both are reducing their costs to the point of being at or below the costs of fossil fuels. Technologies for energy storage and microgrids are also improving quickly and present additional ways to increase the wind and/or solar energy retained for later use with the network management flexibility to provide power to the appropriate locations when needed. As a result, renewable resources continue to gain more market share. The transitioning to renewables as the major resources for power will take some time as the conversion is complex and can have negative impacts if not managed well. While the economics for wind and solar systems continue to improve, the robustness of the WWR site was validated by the repeated queries of developers to place wind and/or solar there. The robust resources and improving technologies portends toward WWR land as a renewable energy site. The business case, however, is not so clear, especially when the potential investment portfolio for ACBCI has several very beneficial and profitable alternatives.« less

  17. Teaching and Popularization of Astronomy in Latin America by the Liada Perspective. (Spanish Title: Enseñanza y Divulgación de la Astronomía en la América Latina en la Perspectiva de la Liada.) Ensino e Divulgação da Astronomia na América Latina na Perspectiva da Liada

    NASA Astrophysics Data System (ADS)

    Bretones, Paulo Sergio

    2008-12-01

    disponibilizados en la página de la Sección, faz-se una análisis y discusión sobre la importancia de tales relatos para finalidades educacionales. Es presentada una Hoja de reporte elaborado como sugestión para presentación de relatos por parte de individuos y instituciones ben como discutida la importancia de la sistematización de experiencias visando mayor visibilidad y cambio de informaciones en el área. Concluí con una evaluación de los proyectos, su potencial y limitaciones, ben como sugestiones de proyectos futuros visando mayor interacción entre los países de la América Latina y tornando disponible la Sección para esta finalidad.

    Esse trabalho visa divulgar e analisar as atividades da Seção de Ensino e Divulgação de Astronomia (SEDA) da Liga Iberoamericana de Astronomia (LIADA). Após um histórico da LIADA, são apresentados os diversos projetos da Seção que conta com a colaboração de coordenadores locais na maioria dos países da América Latina. São apresentados os projetos que visam chamar a atenção do público em geral, estudantes e professores para a observação do céu e posterior envio de relatos para colocação na página da Seção na Internet. Mais especificamente são analisados os projetos e relatos relacionados aos eclipses ocorridos desde o ano 2000. Utilizando-se os arquivos disponibilizados na página da Seção, faz-se uma análise e discussão sobre a importância de tais relatos para finalidades educacionais. É apresentado um formulário elaborado como sugestão para apresentação de relatos por parte de indivíduos e instituições bem como discutida a importância da sistematização de experiências visando maior visibilidade e troca de informações na área. Conclui com uma avaliação dos projetos, seu potencial e limitações, bem como sugestões de projetos futuros visando maior interação entre os países da América Latina e tornando disponível a Seção para esta finalidade.

  18. Superconductivity could occur Na-supersaturated NaCl

    NASA Astrophysics Data System (ADS)

    Hanaki, Koji

    1997-04-01

    A flow-into electron and a flow-out hole mean flow-into of two unit electric c harges. Even if an exciton consisting of an electron and a hole is a neutral q uasi-particle, overlapping of excitons, namely, the bose condensation changes into a superconductor where half the electric current is due to holes moving t oward the reverse direction. The Meisner effect of the bose condensation comes from the precession of the each exciton under the magnetic field^1. Moreo ver, the present mechanism is supported with that superconducting material alw ays has two kinds of carriers. The superconductivity of NaCl comes from the ab ove-mentioned theory. Free stable holes at first and then electrons are produc ed in NaCl when considerable number of Cl^- lattice vacancies are brought in NaCl mainly because some electrons in the Cl-3p filled band fall into the v acancies. The coexistence of two kinds of stable carriers does not always mean the presence of excitons like VO with electrons not paired and localized in e ach V atom though. While, the absorption spectrum of the NaCl has already conf irmed the presence of excitons; the strength of the spectrum seems to indicate the formation of the bose condensation. Thus we could expect a new supercondu ctor. 1) Hanaki B.Am.P.Soc.,40-1(1995)568

  19. DOR activation inhibits anoxic/ischemic Na+ influx through Na+ channels via PKC mechanisms in the cortex.

    PubMed

    Chao, Dongman; He, Xiaozhou; Yang, Yilin; Bazzy-Asaad, Alia; Lazarus, Lawrence H; Balboni, Gianfranco; Kim, Dong H; Xia, Ying

    2012-08-01

    Activation of delta-opioid receptors (DOR) is neuroprotective against hypoxic/ischemic injury in the cortex, which is at least partially related to its action against hypoxic/ischemic disruption of ionic homeostasis that triggers neuronal injury. Na(+) influx through TTX-sensitive voltage-gated Na(+) channels may be a main mechanism for hypoxia-induced disruption of K(+) homeostasis, with DOR activation attenuating the disruption of ionic homeostasis by targeting voltage-gated Na(+) channels. In the present study we examined the role of DOR in the regulation of Na(+) influx in anoxia and simulated ischemia (oxygen-glucose deprivation) as well as the effect of DOR activation on the Na(+) influx induced by a Na(+) channel opener without anoxic/ischemic stress and explored a potential PKC mechanism underlying the DOR action. We directly measured extracellular Na(+) activity in mouse cortical slices with Na(+) selective electrodes and found that (1) anoxia-induced Na(+) influx occurred mainly through TTX-sensitive Na(+) channels; (2) DOR activation inhibited the anoxia/ischemia-induced Na(+) influx; (3) veratridine, a Na(+) channel opener, enhanced the anoxia-induced Na(+) influx; this could be attenuated by DOR activation; (4) DOR activation did not reduce the anoxia-induced Na(+) influx in the presence of chelerythrine, a broad-spectrum PKC blocker; and (5) DOR effects were blocked by PKCβII peptide inhibitor, and PKCθ pseudosubstrate inhibitor, respectively. We conclude that DOR activation inhibits anoxia-induced Na(+) influx through Na(+) channels via PKC (especially PKCβII and PKCθ isoforms) dependent mechanisms in the cortex. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Computational and Experimental Investigations of Na-Ion Conduction in Cubic Na 3PSe 4

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bo, Shou -Hang; Wang, Yan; Kim, Jae Chul

    All-solid-state Na-ion batteries that operate at or close to room temperature are a promising next-generation battery technology with enhanced safety and reduced manufacturing cost. An indispensable component of this technology is the solid-state electrolyte that allows rapid shuttling of the mobile cation (i.e., Na +) between the cathode and anode. However, there are very few fast Na-ion conductors with ionic conductivity approaching that of the liquid counterparts (i.e., 1 mS cm –1). In this work, we present the synthesis and characterization of a fast Na-ion conductor, cubic Na 3PSe 4. This material possesses a room-temperature ionic conductivity exceeding 0.1 mSmore » cm –1 and does not require high-temperature sintering to minimize grain boundary resistance, making it a promising solid-state electrolyte candidate for all-solid-state Na-ion battery applications. On the basis of density functional theory, nudged elastic band, and molecular dynamics investigations, we demonstrate that the framework of cubic Na 3PSe 4 only permits rapid Na + diffusion with the presence of defects, and that the formation of the Na vacancy (charge-balanced by slight Se 2– oxidation) is more energetically favorable among the various defects considered. This finding provides important guidelines to further improve Na-ion conductivity in this class of materials.« less

  1. Computational and Experimental Investigations of Na-Ion Conduction in Cubic Na 3PSe 4

    DOE PAGES

    Bo, Shou -Hang; Wang, Yan; Kim, Jae Chul; ...

    2015-11-17

    All-solid-state Na-ion batteries that operate at or close to room temperature are a promising next-generation battery technology with enhanced safety and reduced manufacturing cost. An indispensable component of this technology is the solid-state electrolyte that allows rapid shuttling of the mobile cation (i.e., Na +) between the cathode and anode. However, there are very few fast Na-ion conductors with ionic conductivity approaching that of the liquid counterparts (i.e., 1 mS cm –1). In this work, we present the synthesis and characterization of a fast Na-ion conductor, cubic Na 3PSe 4. This material possesses a room-temperature ionic conductivity exceeding 0.1 mSmore » cm –1 and does not require high-temperature sintering to minimize grain boundary resistance, making it a promising solid-state electrolyte candidate for all-solid-state Na-ion battery applications. On the basis of density functional theory, nudged elastic band, and molecular dynamics investigations, we demonstrate that the framework of cubic Na 3PSe 4 only permits rapid Na + diffusion with the presence of defects, and that the formation of the Na vacancy (charge-balanced by slight Se 2– oxidation) is more energetically favorable among the various defects considered. This finding provides important guidelines to further improve Na-ion conductivity in this class of materials.« less

  2. Quasi-solid state rechargeable Na-CO2 batteries with reduced graphene oxide Na anodes.

    PubMed

    Hu, Xiaofei; Li, Zifan; Zhao, Yaran; Sun, Jianchao; Zhao, Qing; Wang, Jianbin; Tao, Zhanliang; Chen, Jun

    2017-02-01

    Na-CO 2 batteries using earth-abundant Na and greenhouse gas CO 2 are promising tools for mobile and stationary energy storage, but they still pose safety risks from leakage of liquid electrolyte and instability of the Na metal anode. These issues result in extremely harsh operating conditions of Na-CO 2 batteries and increase the difficulty of scaling up this technology. We report the development of quasi-solid state Na-CO 2 batteries with high safety using composite polymer electrolyte (CPE) and reduced graphene oxide (rGO) Na anodes. The CPE of PVDF-HFP [poly(vinylidene fluoride- co -hexafluoropropylene)]-4% SiO 2 /NaClO 4 -TEGDME (tetraethylene glycol dimethyl ether) has high ion conductivity (1.0 mS cm -1 ), robust toughness, a nonflammable matrix, and strong electrolyte-locking ability. In addition, the rGO-Na anode presents fast and nondendritic Na + plating/stripping (5.7 to 16.5 mA cm -2 ). The improved kinetics and safety enable the constructed rGO-Na/CPE/CO 2 batteries to successfully cycle in wide CO 2 partial pressure window (5 to 100%, simulated car exhaust) and especially to run for 400 cycles at 500 mA g -1 with a fixed capacity of 1000 mA·hour g -1 in pure CO 2 . Furthermore, we scaled up the reversible capacity to 1.1 A·hour in pouch-type batteries (20 × 20 cm, 10 g, 232 Wh kg -1 ). This study makes quasi-solid state Na-CO 2 batteries an attractive prospect.

  3. Quasi–solid state rechargeable Na-CO2 batteries with reduced graphene oxide Na anodes

    PubMed Central

    Hu, Xiaofei; Li, Zifan; Zhao, Yaran; Sun, Jianchao; Zhao, Qing; Wang, Jianbin; Tao, Zhanliang; Chen, Jun

    2017-01-01

    Na-CO2 batteries using earth-abundant Na and greenhouse gas CO2 are promising tools for mobile and stationary energy storage, but they still pose safety risks from leakage of liquid electrolyte and instability of the Na metal anode. These issues result in extremely harsh operating conditions of Na-CO2 batteries and increase the difficulty of scaling up this technology. We report the development of quasi–solid state Na-CO2 batteries with high safety using composite polymer electrolyte (CPE) and reduced graphene oxide (rGO) Na anodes. The CPE of PVDF-HFP [poly(vinylidene fluoride-co-hexafluoropropylene)]–4% SiO2/NaClO4–TEGDME (tetraethylene glycol dimethyl ether) has high ion conductivity (1.0 mS cm−1), robust toughness, a nonflammable matrix, and strong electrolyte-locking ability. In addition, the rGO-Na anode presents fast and nondendritic Na+ plating/stripping (5.7 to 16.5 mA cm−2). The improved kinetics and safety enable the constructed rGO-Na/CPE/CO2 batteries to successfully cycle in wide CO2 partial pressure window (5 to 100%, simulated car exhaust) and especially to run for 400 cycles at 500 mA g−1 with a fixed capacity of 1000 mA·hour g−1 in pure CO2. Furthermore, we scaled up the reversible capacity to 1.1 A·hour in pouch-type batteries (20 × 20 cm, 10 g, 232 Wh kg−1). This study makes quasi–solid state Na-CO2 batteries an attractive prospect. PMID:28164158

  4. High-resolution molecular-beam spectroscopy of NaCN and Na 13CN

    NASA Astrophysics Data System (ADS)

    van Vaals, J. J.; Meerts, W. Leo; Dymanus, A.

    The sodium cyanide molecule was studied by molecular-beam electric-resonance spectroscopy in the microwave region. We used the seeded-beam technique to produce a supersonic beam with strong translational, rotational and vibrational cooling. In the frequency range 9.5-40 GHz we observed and identified for NaCN 186 and for Na 13CN 107 hyperfine transitions in 20 and 16 rotational transitions, respectively, all in the ground vibrational state. The rotational, the five quartic and three sextic centrifugal distortion constants of NaCN are: A″ = 57921.954(7) MHz; B″ = 8369.312(2) MHz, C″ = 7272.712(2) MHz. All quadrupole and several spin-rotation coupling constants for the hyperfine interaction were evaluated. The quadrupole coupling constants (in MHz) for NaCN are: eQq12(Na) = -5.344(5), eQq12 = 2.397(7). eQq12(N) = 2.148(4), eQq12(N) = -4.142(5). From these constants and those of Na 13CN we have determined the principal components of the quadrupole coupling tensor for potassium and nitrogen. The structure of sodium cyanide evaluated from the rotational constants of NaCN and Na 13CN was found to be T shaped, similar to the structure of KCN but completely different from the linear isocyanide configuration of LiNC. The effective structural parameters for sodium cyanide in the ground vibrational state are: rCN = 1.170(4) Å, rNaC = 2.379(15) Å, rN12N = 2.233(15) Å, in gratifying agreement with ab initio calculations. Both the geometrical structure and the hyperfine coupling justify the conclusion that the CN group in gaseous sodium cyanide approximately can be considered as a free CN - ion.

  5. Synthesis of zeolites Na-A and Na-X from tablet compressed and calcinated coal fly ash

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Gao, Wenyan; Liu, Xin; Zhang, Yifu; Meng, Changgong

    2017-10-01

    Zeolites Na-A and Na-X are important synthetic zeolites widely used for separation and adsorption in industry. It is of great significance to develop energy-efficient routines that can synthesize zeolites Na-A and Na-X from low-cost raw materials. Coal fly ash (CFA) is the major residue from the combustion of coal and biomass containing more than 85% SiO2 and Al2O3, which can readily replace the conventionally used sodium silicate and aluminate for zeolite synthesis. We used Na2CO3 to replace the expensive NaOH used for the calcination of CFA and showed that tablet compression can enhance the contact with Na2CO3 for the activation of CFA through calcination for the synthesis of zeolites Na-A and Na-X under mild conditions. We optimized the control variables for zeolite synthesis and showed that phase-pure zeolite Na-A can be synthesized with CFA at reactant molar ratio, hydrothermal reaction temperature and reaction time of 1.3Na2O: 0.6Al2O3: 1SiO2: 38H2O at 80°C for 6 h, respectively, while phase-pure zeolite Na-X can be synthesized at 2.2Na2O: 0.2Al2O3: 1SiO2: 88H2O at 100°C for 8 h, respectively. The composition, morphology, specific surface area, vibration spectrum and thermogravimetry of synthesized Na-A and Na-X were further characterized.

  6. Structural and Na-ion conduction characteristics of Na 3 PS x Se 4-x

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bo, Shou-Hang; Wang, Yan; Ceder, Gerbrand

    The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4-x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4-x more » identified a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4-x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

  7. Formation of Si grains from a NaSi melt prepared by reaction of SiO2 and Na

    NASA Astrophysics Data System (ADS)

    Yamane, Hisanori; Morito, Haruhiko; Uchikoshi, Masahito

    2013-08-01

    A mixture of Na2SiO3 and NaSi was found to be formed by reaction of SiO2 and Na at 650 °C as follows: 5Na+3SiO2→2Na2SiO3+NaSi. Single crystals of NaSi were grown by cooling the mixture of Na2SiO3 and NaSi with an excess amount of Na from 850 °C, and polycrystalline Si was obtained by vaporization of Na from the crystals. Coarse grains of Si were also crystallized by Na evaporation after the formation of Na2SiO3 and Si-dissolved liquid Na at 830 °C. The Si grains were collected by washing the product with water. The yield of the Si grains was 85% of the ideal amount expected from the reaction.

  8. Identificação de radiofontes puntiformes presentes na região observada pelo telescópio BEAST

    NASA Astrophysics Data System (ADS)

    Oliveira, M. S.; Wuensche, C. A.; Leonardi, R.; Tello, C.

    2003-08-01

    Radiofontes extragalácticas são um dos principais contaminantes nas medidas da Radiação Cósmica de Fundo (RCF) em freqüências abaixo de 200 GHz. O estudo de seu comportamento espectral permite determinar a contribuição destas fontes às anisotropias intrísincas da RCF. Um dos experimentos recentes concebidos para estudar a RCF é o BEAST (Background Emission Anisotropy Scanning Telescope), cujos primeiros resultados foram publicados em fevereiro de 2003. Nos últimos meses, geramos mapas do céu nas freqüências de 30 GHz e 41 GHz, para um total de 648 horas de observação entre julho e outubro de 2002. Identificamos 4 fontes puntiformes extragalácticas na região do céu situada entre 0h < RA < 24 h e +32° < DEC < +42°, com relação S/R > 4,3 e situadas a pelo menos 25° acima do Plano Galáctico. Suas contrapartidas em 5 GHz, segundo o catálogo GB6, são: J1613+3412, J1635+3808, J0927+3902 e J1642+3948. Estas fontes também foram identificadas pelo satélite WMAP sendo que três coincidem com as observadas pelo BEAST dentro da incerteza do feixe do telescópio e a quarta encontra-se bastante próxima (J1613+3412), embora não seja coincidente. As estimativas preliminares de fluxos obtidas para esses objetos são, respectivamente, 0,51; 0,97; 1,08 e 1,6 Jy em 41 GHz. Usando estes resultados e medidas de fluxos em outras frequências existentes na literatura, apresentamos uma estimativa dos índices espectrais destes objetos no intervalo de frequências entre 4,85 GHz e 41 GHz.

  9. The Impact of Prostate Cancer Treatment-Related Symptoms on Low-Income Latino Couples

    DTIC Science & Technology

    2011-03-01

    decir la…la…palabra cáncer para usted? Patient ID#1866: Pues…casi es básicamente “aguas, que estás en peligro !” ¿Si? Interviewer AS: Uh huh...primero era acabar con el cáncer Interviewer AS: Si Principal Investigator: Maliski, SL 36 Patient ID#1866: Eso es el peligro de perder la vida

  10. Medida de los beneficios económicos de la integridad ecológica del Río Mameyes en Puerto Rico

    Treesearch

    Armando Gonzalez-Caban; John Loomis

    1999-01-01

    Se realizó una valoración de contingencia a través de una encuesta en persona de los jefes de familia puertorriqueños, de abril a agosto de 1995, para estimar su consentimiento-parapagar por la preservación de niveles de agua en el Río Mameyes, y evitar la construcción de la represa propuesta...

  11. The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

    DOE PAGES

    Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

    2018-05-09

    In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

  12. The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

    In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

  13. 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.

  14. NA62 and NA48/2 results on search for Heavy Neutral Leptons

    NASA Astrophysics Data System (ADS)

    Lamanna, Gianluca; Aliberti, R.; Ambrosino, F.; Ammendola, R.; Angelucci, B.; Antonelli, A.; Anzivino, G.; Arcidiacono, R.; Barbanera, M.; Biagioni, A.; Bician, L.; Biino, C.; Bizzeti, A.; Blazek, T.; Bloch-Devaux, B.; Bonaiuto, V.; Boretto, M.; Bragadireanu, M.; Britton, D.; Brizioli, F.; Brunetti, M. B.; Bryman, D.; Bucci, F.; Capussela, T.; Ceccucci, A.; Cenci, P.; Cerny, V.; Cerri, C.; Checcucci, B.; Conovaloff, A.; Cooper, P.; Cortina Gil, E.; Corvino, M.; Costantini, F.; Cotta Ramusino, A.; Coward, D.; D'Agostini, G.; Dainton, J.; Dalpiaz, P.; Danielsson, H.; De Simone, N.; Di Filippo, D.; Di Lella, L.; Doble, N.; Dobrich, B.; Duval, F.; Duk, V.; Engelfried, J.; Enik, T.; Estrada-Tristan, N.; Falaleev, V.; Fantechi, R.; Fascianelli, V.; Federici, L.; Fedotov, S.; Filippi, A.; Fiorini, M.; Fry, J.; Fu, J.; Fucci, A.; Fulton, L.; Gamberini, E.; Gatignon, L.; Georgiev, G.; Ghinescu, S.; Gianoli, A.; Giorgi, M.; Giudici, S.; Gonnella, F.; Goudzovski, E.; Graham, C.; Guida, R.; Gushchin, E.; Hahn, F.; Heath, H.; Husek, T.; Hutanu, O.; Hutchcroft, D.; Iacobuzio, L.; Iacopini, E.; Imbergamo, E.; Jenninger, B.; Kampf, K.; Kekelidze, V.; Kholodenko, S.; Khoriauli, G.; Khotyantsev, A.; Kleimenova, A.; Korotkova, A.; Koval, M.; Kozhuharov, V.; Kucerova, Z.; Kudenko, Y.; Kunze, J.; Kurochka, V.; Kurshetsov, V.; Lanfranchi, G.; Lamanna, G.; Latino, G.; Laycock, P.; Lazzeroni, C.; Lenti, M.; Lehmann Miotto, G.; Leonardi, E.; Lichard, P.; Litov, L.; Lollini, R.; Lomidze, D.; Lonardo, A.; Lubrano, P.; Lupi, M.; Lurkin, N.; Madigozhin, D.; Mannelli, I.; Mannocchi, G.; Mapelli, A.; Marchetto, F.; Marchevski, R.; Martellotti, S.; Massarotti, P.; Massri, K.; Maurice, E.; Medvedeva, M.; Mefodev, A.; Menichetti, E.; Migliore, E.; Minucci, E.; Mirra, M.; Misheva, M.; Molokanova, N.; Moulson, M.; Movchan, S.; Napolitano, M.; Neri, I.; Newson, F.; Norton, A.; Noy, M.; Numao, T.; Obraztsov, V.; Ostankov, A.; Padolski, S.; Page, R.; Palladino, V.; Parkinson, C.; Pedreschi, E.; Pepe, M.; Perrin-Terrin, M.; Peruzzo, L.; Petrov, P.; Petrucci, F.; Piandani, R.; Piccini, M.; Pinzino, J.; Polenkevich, I.; Pontisso, L.; Potrebenikov, Yu.; Protopopescu, D.; Raggi, M.; Romano, A.; Rubin, P.; Ruggiero, G.; Ryjov, V.; Salamon, A.; Santoni, C.; Saracino, G.; Sargeni, F.; Semenov, V.; Sergi, A.; Shaikhiev, A.; Shkarovskiy, S.; Soldi, D.; Sougonyaev, V.; Sozzi, M.; Spadaro, T.; Spinella, F.; Sturgess, A.; Swallow, J.; Trilov, S.; Valente, P.; Velghe, B.; Venditti, S.; Vicini, P.; Volpe, R.; Vormstein, M.; Wahl, H.; Wanke, R.; Wrona, B.; Yushchenko, O.; Zamkovsky, M.; Zinchenko, A.

    2018-05-01

    In this paper we present new results on upper limits for the search of Heavy Neutral Leptons (HNL) with data collected by NA48/2 (2003-2004), NA62-RK (2007) and NA62 (2015) CERN experiments. The data collected with different trigger configuration allow to search for both long and short living heavy neutrinos in the mass range below the kaon mass. In addition the status of the search for K+ → π+vv with the NA62 detector will be briefly presented.

  15. Drosophila as a Model for Epilepsy: bss Is a Gain-of-Function Mutation in the Para Sodium Channel Gene That Leads to Seizures

    PubMed Central

    Parker, Louise; Padilla, Miguel; Du, Yuzhe; Dong, Ke; Tanouye, Mark A.

    2011-01-01

    We report the identification of bang senseless (bss), a Drosophila melanogaster mutant exhibiting seizure-like behaviors, as an allele of the paralytic (para) voltage-gated Na+ (NaV) channel gene. Mutants are more prone to seizure episodes than normal flies because of a lowered seizure threshold. The bss phenotypes are due to a missense mutation in a segment previously implicated in inactivation, termed the “paddle motif” of the NaV fourth homology domain. Heterologous expression of cDNAs containing the bss1 lesion, followed by electrophysiology, shows that mutant channels display altered voltage dependence of inactivation compared to wild type. The phenotypes of bss are the most severe of the bang-sensitive mutants in Drosophila and can be ameliorated, but not suppressed, by treatment with anti-epileptic drugs. As such, bss-associated seizures resemble those of pharmacologically resistant epilepsies caused by mutation of the human NaV SCN1A, such as severe myoclonic epilepsy in infants or intractable childhood epilepsy with generalized tonic-clonic seizures. PMID:21115970

  16. Groundwater for urban water supplies in northern China - An overview

    NASA Astrophysics Data System (ADS)

    Zaisheng, Han

    Groundwater plays an important role for urban and industrial water supply in northern China. More than 1000 groundwater wellfields have been explored and installed. Groundwater provides about half the total quantity of the urban water supply. Complete regulations and methods for the exploration of groundwater have been established in the P.R. China. Substantial over-exploitation of groundwater has created environmental problems in some cities. Some safeguarding measures for groundwater-resource protection have been undertaken. Résumé Les eaux souterraines jouent un rôle important dans l'approvisionnement en eau des agglomérations et des industries du nord de la Chine. Les explorations ont conduit à mettre en place plus de 1000 champs de puits captant des eaux souterraines. Les eaux souterraines satisfont environ la moitié des besoins en eau des villes. Une réglementation complète et des méthodes d'exploration des eaux souterraines ont étéétablies en République Populaire de Chine. Une surexploitation très nette est à l'origine de problèmes environnementaux dans certaines villes. Des mesures ont été prises pour protéger la ressource en eau souterraine. Resumen El agua subterránea desempeña un papel importante en el suministro de agua para uso doméstico e industrial en la China septentrional. Se han explorado y puesto en marcha más de 1000 campos de explotación de aguas subterráneas, que proporcionan cerca de la mitad del total del suministro urbano. En la República Popular de China se han definido totalmente la legislación y la metodología para realizar estas explotaciones. La gran sobreexplotación en algunas ciudades ha creado algunos problemas medioambientales. Como consecuencia, se han llevado a cabo algunas medidas de protección de los recursos de aguas subterráneas.

  17. Physiological responses to salt stress of salt-adapted and directly salt (NaCl and NaCl+Na2SO4 mixture)-stressed cyanobacterium Anabaena fertilissima.

    PubMed

    Swapnil, Prashant; Rai, Ashwani K

    2018-05-01

    Soil salinity in nature is generally mixed type; however, most of the studies on salt toxicity are performed with NaCl and little is known about sulfur type of salinity (Na 2 SO 4 ). Present study discerns the physiologic mechanisms responsible for salt tolerance in salt-adapted Anabaena fertilissima, and responses of directly stressed parent cells to NaCl and NaCl+Na 2 SO 4 mixture. NaCl at 500 mM was lethal to the cyanobacterium, whereas salt-adapted cells grew luxuriantly. Salinity impaired gross photosynthesis, electron transport activities, and respiration in parent cells, but not in the salt-adapted cells, except a marginal increase in PSI activity. Despite higher Na + concentration in the salt mixture, equimolar NaCl appeared more inhibitive to growth. Sucrose and trehalose content and antioxidant activities were maximal in 250 mM NaCl-treated cells, followed by salt mixture and was almost identical in salt-adapted (exposed to 500 mm NaCl) and control cells, except a marginal increase in ascorbate peroxidase activity and an additional fourth superoxide dismutase isoform. Catalase isoform of 63 kDa was induced only in salt-stressed cells. Salinity increased the uptake of intracellular Na + and Ca 2+ and leakage of K + in parent cells, while cation level in salt-adapted cells was comparable to control. Though there was differential increase in intracellular Ca 2+ under different salt treatments, ratio of Ca 2+ /Na + remained the same. It is inferred that stepwise increment in the salt concentration enabled the cyanobacterium to undergo priming effect and acquire robust and efficient defense system involving the least energy.

  18. Simulating Asymmetric Top Impurities in Superfluid Clusters: A para-Water Dopant in para-Hydrogen.

    PubMed

    Zeng, Tao; Li, Hui; Roy, Pierre-Nicholas

    2013-01-03

    We present the first simulation study of bosonic clusters doped with an asymmetric top molecule. The path-integral Monte Carlo method with the latest methodological advance in treating rigid-body rotation [Noya, E. G.; Vega, C.; McBride, C. J. Chem. Phys.2011, 134, 054117] is employed to study a para-water impurity in para-hydrogen clusters with up to 20 para-hydrogen molecules. The growth pattern of the doped clusters is similar in nature to that of pure clusters. The para-water molecule appears to rotate freely in the cluster. The presence of para-water substantially quenches the superfluid response of para-hydrogen with respect to the space-fixed frame.

  19. Vacancy-Controlled Na+ Superion Conduction in Na11 Sn2 PS12.

    PubMed

    Duchardt, Marc; Ruschewitz, Uwe; Adams, Stefan; Dehnen, Stefanie; Roling, Bernhard

    2018-01-26

    Highly conductive solid electrolytes are crucial to the development of efficient all-solid-state batteries. Meanwhile, the ion conductivities of lithium solid electrolytes match those of liquid electrolytes used in commercial Li + ion batteries. However, concerns about the future availability and the price of lithium made Na + ion conductors come into the spotlight in recent years. Here we present the superionic conductor Na 11 Sn 2 PS 12 , which possesses a room temperature Na + conductivity close to 4 mS cm -1 , thus the highest value known to date for sulfide-based solids. Structure determination based on synchrotron X-ray powder diffraction data proves the existence of Na + vacancies. As confirmed by bond valence site energy calculations, the vacancies interconnect ion migration pathways in a 3D manner, hence enabling high Na + conductivity. The results indicate that sodium electrolytes are about to equal the performance of their lithium counterparts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Experimental and first-principles study of photoluminescent and optical properties of Na-doped CuAlO2: the role of the NaAl-2Na i complex

    NASA Astrophysics Data System (ADS)

    Liu, Ruijian; Li, Yongfeng; Yao, Bin; Ding, Zhanhui; Deng, Rui; Zhang, Ligong; Zhao, Haifeng; Liu, Lei

    2015-08-01

    We report that a band-tail emission at 3.08 eV, lower than near-band-edge energy, is observed in photoluminescence measurements of bulk Na-doped CuAlO2. The band-tail emission is attributed to Na-related defects. Electronic structure calculations based on the first-principles method demonstrate that the donor-acceptor compensated complex of NaAl-2Na i in Na-doped CuAlO2 plays a key role in leading to the band-tail emission and bandgap narrowing. Furthermore, Hall effect measurements indicates that the hole concentration in CuAlO2 is independent on Na doping, which is well understood by the donor-acceptor compensation effect of NaAl-2Na i complex.

  1. Structural and Na-ion conduction characteristics of Na 3PS xSe 4–x

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bo, Shou -Hang; Wang, Yan; Ceder, Gerbrand

    The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4–x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4–x identifiedmore » a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4–x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

  2. Structural and Na-ion conduction characteristics of Na 3PS xSe 4–x

    DOE PAGES

    Bo, Shou -Hang; Wang, Yan; Ceder, Gerbrand

    2016-05-19

    The recent discovery of the isostructrual cubic Na 3PS 4 and Na 3PSe 4 as fast Na-ion conductors provided a general structural framework for the exploration of new sodium superionic conductors. In this work, we systematically investigated the structures and ionic conduction characteristics of a series of compounds with the general chemical formula of Na 3PS xSe 4–x. Synthesis of Na 3PS 4 under different conditions (e.g., temperature, reaction vessel, mass of the precursors) reveals the reactivity of the precursors with the reaction tubes, producing different polymorphs. X-ray diffraction studies on the solid solution phases Na 3PS xSe 4–x identifiedmore » a tetragonal-to-cubic phase transition with increasing Se concentration. This observation is consistent with the computed stability of the tetragonal and cubic polymorphs, where the energy difference between the two polymorphs becomes very close to zero in Se-rich compositions. Furthermore, ab initio molecular dynamic simulations suggest that the fast Na-ion conduction in Na 3PS xSe 4–x may not be causally related with the symmetry or the composition of these phases. The formation of defects, instead, enables fast Na-ion conduction in this class of materials.« less

  3. A thermochemical explanation for the stability of NaCl3 and NaCl7

    NASA Astrophysics Data System (ADS)

    Fernandes de Farias, Robson

    2017-03-01

    Thermodynamically stable cubic and orthorhombic NaCl3 as well as NaCl7 have been synthesized (Zhang et al., 2013). In the present work, a thermochemical explanation for the stability of such unusual sodium chlorides is provided, based on lattice energy values. Using the Glasser-Jenkins generalized equation (Glasser and Jenkins, 2000) lattice energies (kJ mol-1) of -162.5, -168.9 and -113.1 are calculated for Pm3n NaCl3, Pnma NaCl3 and NaCl7, respectively. It is postulated that any NaxCly compound could be synthesized, if the ionic character of the Nasbnd Cl bond in the prepared compound remains around 80%, and the sodium charge below unit.

  4. On efeito do achatamento nos pontos de equilíbrio e na dinâmica de sistemas coorbitais

    NASA Astrophysics Data System (ADS)

    Mourão, D. C.; Winter, O. C.; Yokoyama, T.

    2003-08-01

    Neste trabalho analisamos o efeito do achatamento do corpo principal nos pontos de equilíbrio lagrangianos e na configuração de órbitas girino-ferradura. Enfatizamos os sistemas coorbitais de satélites de Saturno, pois se encontram em relativa proximidade com o planeta, em que o efeito do achatamento se torna mais evidente. O estudo é dividido em três etapas independentes. Na primeira fase analisamos as equações de movimento do problema restrito de três corpos considerando o efeito do achatamento, e através do balanceamento de forças buscamos a nova configuração dos pontos de equilíbrio lagrangianos. Concluímos, nesta etapa, que os pontos de equilíbrio estáveis apresentam um pequeno deslocamento definido pelo parâmetro de achatamento, não podendo ser mais representados por triângulos eqüiláteros. Aplicamos este resultado aos satélites coorbitais de Tetis e Dione, encontrando as posições de equilíbrio levemente deslocadas em relação ao caso sem achatamento. Na segunda fase visamos o sistema Saturno-Jano-Epimeteu, que por se tratar de um sistema de massas comparáveis, optamos por desenvolver as equações de Yoder et al (Icarus 53, pág 431-443, 1983), que permitem determinar os pontos de equilíbrio e a amplitude de oscilação angular das órbitas girino-ferradura para o problema não-restrito de três corpos, porém, no nosso estudo consideramos o efeito do achatamento do corpo principal nestas equações. Encontramos que a distância angular entre satélites, quando em posição de equilíbrio estável, diminui quanto maior for o parâmetro de achatamento do corpo principal. Além disso, a órbita de transição girino-ferradura possui largura angular menor em relação ao caso sem achatamento. Por fim, realizamos integrações numéricas para os casos reais de coorbitais de Saturno comparando com os resultados analíticos. Nestas integrações simulamos diversas órbitas girino-ferradura com diferentes parâmetros de achatamento

  5. Long range intermolecular interactions between the alkali diatomics Na2, K2, and NaK

    NASA Astrophysics Data System (ADS)

    Zemke, Warren T.; Byrd, Jason N.; Michels, H. Harvey; Montgomery, John A.; Stwalley, William C.

    2010-06-01

    Long range interactions between the ground state alkali diatomics Na2-Na2, K2-K2, Na2-K2, and NaK-NaK are examined. Interaction energies are first determined from ab initio calculations at the coupled-cluster with singles, doubles, and perturbative triples [CCSD(T)] level of theory, including counterpoise corrections. Long range energies calculated from diatomic molecular properties (polarizabilities and dipole and quadrupole moments) are then compared with the ab initio energies. A simple asymptotic model potential ELR=Eelec+Edisp+Eind is shown to accurately represent the intermolecular interactions for these systems at long range.

  6. Documentation and Testing of the WEAP Model for the Rio Grande/Bravo Basin

    DTIC Science & Technology

    2006-08-01

    border between Texas and the Mexican states of Coahuila, Nuevo Leon and Tamaulipas (Appendix B, Figure 32). There are four reservoirs of interest in this...Camargo - Ciudad Acuna - Ciudad Anhuac - Ciudad Juarez - Matamoros - Metropolitan Monterrey - Nuevo Laredo - Reynosa - Piedras Negras...Rivera, and Jorge A. Hidalgo. (2001). “Sistema de apoyo a la toma de decisions para el manejo integral del agua en cuencas.” IMTA/CNA, Proyecto

  7. Hydrometric, Hydrochemical, and Hydrogeophysical Runoff Characterization Across Multiple Land Covers in the Agua Salud Project, Panama

    NASA Astrophysics Data System (ADS)

    Litt, Guy Finley

    As the Panama Canal Authority faces sensitivity to water shortages, managing water resources becomes crucial for the global shipping industry's security. These studies address knowledge gaps in tropical water resources to aid hydrological model development and validation. Field-based hydrological investigations in the Agua Salud Project within the Panama Canal Watershed employed multiple tools across a variety of land covers to investigate hydrological processes. Geochemical tracers informed where storm runoff in a stream comes from and identified electrical conductivity (EC) as an economical, high sample frequency tracer during small storms. EC-based hydrograph separation coupled with hydrograph recession rate analyses identified shallow and deep groundwater storage-discharge relationships that varied by season and land cover. A series of plot-scale electrical resistivity imaging geophysical experiments coupled with rainfall simulation characterized subsurface flow pathway behavior and quantified respectively increasing infiltration rates across pasture, 10 year old secondary succession forest, teak (tectona grandis), and 30 year old secondary succession forest land covers. Additional soil water, groundwater, and geochemical studies informed conceptual model development in subsurface flow pathways and groundwater, and identified future research needs.

  8. Preliminary Image Map of the 2007 Buckweed Fire Perimeter, Agua Dulce Quadrangle, Los Angeles County, California

    USGS Publications Warehouse

    Clark, Perry S.; Scratch, Wendy S.; Bias, Gaylord W.; Stander, Gregory B.; Sexton, Jenne L.; Krawczak, Bridgette J.

    2008-01-01

    In the fall of 2007, wildfires burned out of control in southern California. The extent of these fires encompassed large geographic areas that included a variety of landscapes from urban to wilderness. The U.S. Geological Survey National Geospatial Technical Operations Center (NGTOC) is currently (2008) developing a quadrangle-based 1:24,000-scale image map product. One of the concepts behind the image map product is to provide an updated map in electronic format to assist with emergency response. This image map is one of 55 preliminary image map quadrangles covering the areas burned by the southern California wildfires. Each map is a layered, geo-registered Portable Document Format (.pdf) file. For more information about the layered geo-registered .pdf, see the readme file (http://pubs.usgs.gov/of/2008/1029/downloads/CA_Agua_Dulce_of2008-1029_README.txt). To view the areas affected and the quadrangles mapped in this preliminary project, see the map index (http://pubs.usgs.gov/of/2008/1029/downloads/CA_of2008_1029-1083_index.pdf) provided with this report.

  9. Route, mechanism, and implications of proton import during Na+/K+ exchange by native Na+/K+-ATPase pumps

    PubMed Central

    Vedovato, Natascia

    2014-01-01

    A single Na+/K+-ATPase pumps three Na+ outwards and two K+ inwards by alternately exposing ion-binding sites to opposite sides of the membrane in a conformational sequence coupled to pump autophosphorylation from ATP and auto-dephosphorylation. The larger flow of Na+ than K+ generates outward current across the cell membrane. Less well understood is the ability of Na+/K+ pumps to generate an inward current of protons. Originally noted in pumps deprived of external K+ and Na+ ions, as inward current at negative membrane potentials that becomes amplified when external pH is lowered, this proton current is generally viewed as an artifact of those unnatural conditions. We demonstrate here that this inward current also flows at physiological K+ and Na+ concentrations. We show that protons exploit ready reversibility of conformational changes associated with extracellular Na+ release from phosphorylated Na+/K+ pumps. Reversal of a subset of these transitions allows an extracellular proton to bind an acidic side chain and to be subsequently released to the cytoplasm. This back-step of phosphorylated Na+/K+ pumps that enables proton import is not required for completion of the 3 Na+/2 K+ transport cycle. However, the back-step occurs readily during Na+/K+ transport when external K+ ion binding and occlusion are delayed, and it occurs more frequently when lowered extracellular pH raises the probability of protonation of the externally accessible carboxylate side chain. The proton route passes through the Na+-selective binding site III and is distinct from the principal pathway traversed by the majority of transported Na+ and K+ ions that passes through binding site II. The inferred occurrence of Na+/K+ exchange and H+ import during the same conformational cycle of a single molecule identifies the Na+/K+ pump as a hybrid transporter. Whether Na+/K+ pump–mediated proton inflow may have any physiological or pathophysiological significance remains to be clarified. PMID

  10. Active corrosion protection of AA2024 by sol-gel coatings with corrosion inhibitors =

    NASA Astrophysics Data System (ADS)

    Yasakau, Kiryl

    industriais mostraram que estes novos revestimentos sao compativeis com os esquemas de pintura convencionais actualmente em uso. A estabilidade e o prazo de validade das formulacoes foram optimizados modificando a temperatura de armazenamento e a quantidade de agua usada durante a sintese. As formulacoes sol-gel foram dopadas com os inibidores seleccionados durante a primeira etapa e as propriedades anticorrosivas passivas e activas dos revestimentos obtidos foram estudadas numa terceira etapa do trabalho. Os resultados comprovam a influencia dos inibidores nas propriedades anticorrosivas dos revestimentos sol-gel. Em alguns casos a accao activa dos inibidores combinou-se com a proteccao passiva dada pelo revestimento mas noutros casos tera ocorrido interaccao quimica entre o inibidor e a matriz de sol-gel, de onde resultou a perda de propriedades protectoras do sistema combinado. Atendendo aos problemas provocados pela adicao directa dos inibidores na formulacao sol-gel procurou-se, numa quarta etapa, formas alternativas de incorporacao. Na primeira, produziu-se uma camada de titania nanoporosa na superficie da liga metalica que serviu de reservatorio para os inibidores. O revestimento sol-gel foi aplicado por cima da camada nanoporosa. Os inibidores armazenados nos poros actuam quando o substrato fica exposto ao ambiente agressivo. Numa segunda, os inibidores foram armazenados em nano-reservatorios de silica ou em nanoargilas (halloysite), os quais foram revestidos por polielectrolitos montados camada a camada. A terceira alternativa consistiu no uso de nano-fios de molibdato de cerio amorfo como inibidores anticorrosivos nanoparticulados. Os nano-reservatorios foram incorporados durante a sintese do sol-gel. Qualquer das abordagens permitiu eliminar o efeito negativo do inibidor sobre a estabilidade da matriz do sol-gel. Os revestimentos sol-gel desenvolvidos neste trabalho apresentaram proteccao anticorrosiva activa e capacidade de auto-reparacao. Os resultados obtidos

  11. Long range intermolecular interactions between the alkali diatomics Na(2), K(2), and NaK.

    PubMed

    Zemke, Warren T; Byrd, Jason N; Michels, H Harvey; Montgomery, John A; Stwalley, William C

    2010-06-28

    Long range interactions between the ground state alkali diatomics Na(2)-Na(2), K(2)-K(2), Na(2)-K(2), and NaK-NaK are examined. Interaction energies are first determined from ab initio calculations at the coupled-cluster with singles, doubles, and perturbative triples [CCSD(T)] level of theory, including counterpoise corrections. Long range energies calculated from diatomic molecular properties (polarizabilities and dipole and quadrupole moments) are then compared with the ab initio energies. A simple asymptotic model potential E(LR)=E(elec)+E(disp)+E(ind) is shown to accurately represent the intermolecular interactions for these systems at long range.

  12. Effect of NaNO3 concentration on anodic electrochemical behavior on the Sb surface in NaOH solution

    NASA Astrophysics Data System (ADS)

    He, Yun-long; Xu, Rui-dong; He, Shi-wei; Chen, Han-sen; Li, Kuo; Zhu, Yun; Shen, Qing-feng

    2018-03-01

    The effect of NaNO3 concentration on the anodic electrochemical behavior of antimony in 4 M NaOH solution was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. The mechanism of NO 3 - concentration effect on the anodic electrochemical behavior of antimony was proposed, and its availability was confirmed by experimental results. The effect of NaNO3 on the anodic behavior of antimony in NaOH solution can be interpreted as a stepwise formation of different antimony compounds with different NaNO3 concentrations. Metallic antimony is apt to be oxidized into Sb2O3 within the NaNO3 concentration range of 0-0.48 M. NaSbO3 can be found on the antimony surface when the NaNO3 concentration increases gradually. Insoluable NaSbO3 inhibits the anodic oxidation of antimony due to its shielding effect on the mass transport of the reactants and products. Surface morphology and composition were analyzed by X-ray photoelectron spectroscopy (XPS), scanning electronic microscopy (SEM), and electron dispersion spectroscopy (EDS) analyses. Results indicate that the anodic oxidation layer is composed of Sb2O3, NaSbO3, and Sb. The atomic proportion of antimony in the form of NaSbO3 increases with increasing NaNO3 concentration due to the powerful oxidizing property of NaNO3.

  13. 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.

  14. On the Stability of NaO2 in Na-O2 Batteries.

    PubMed

    Liu, Chenjuan; Carboni, Marco; Brant, William R; Pan, Ruijun; Hedman, Jonas; Zhu, Jiefang; Gustafsson, Torbjörn; Younesi, Reza

    2018-04-25

    Na-O 2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li-O 2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO 2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na-O 2 batteries.

  15. Profilaxia de tromboembolismo venoso na gestação

    PubMed Central

    de Oliveira, André Luiz Malavasi Longo; Marques, Marcos Arêas

    2016-01-01

    Resumo O tromboembolismo venoso é importante causa de morbidade e mortalidade obstétrica. Durante a gestação, o risco de sua ocorrência aumenta entre cinco e dez vezes quando comparado ao de mulheres não gestantes de mesma idade. Associado a esse fato, a gestante apresenta algumas limitações para o diagnóstico clínico (alta frequência de dor e edema nos membros inferiores), ecográfico (menor sensibilidade e especificidade no diagnóstico de trombose venosa de ilíaca com a evolução da gestação) e laboratorial (o D-dímero apresenta aumento progressivo no decorrer da gravidez). Uma estratificação criteriosa de risco de tromboembolismo venoso de cada mulher antes da gestação pode diminuir a incidência dessa doença, frequente e de difícil diagnóstico na gravidez, e suas complicações. PMID:29930607

  16. 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

  17. The influence of manganese treatment on the distribution of metal elements in rats and the protection by sodium para-amino salicylic acid.

    PubMed

    Yuan, Zong-Xiang; Chen, Hai-Bin; Li, Shao-Jun; Huang, Xiao-Wei; Mo, Yu-Huan; Luo, Yi-Ni; He, Sheng-Nan; Deng, Xiang-Fa; Lu, Guo-Dong; Jiang, Yue-Ming

    2016-07-01

    Manganese (Mn) overexposure induced neurological damages, which could be potentially protected by sodium para-aminosalicylic acid (PAS-Na). In this study, we systematically detected the changes of divalent metal elements in most of the organs and analyzed the distribution of the metals in Mn-exposed rats and the protection by PAS-Na. Sprague Dawley (SD) rats received intraperitoneal injections of 15mg/kg MnCl2·4H2O (5d/week for 3 weeks), followed by subcutaneous (back) injections of PAS-Na (100 and 200mg/kg, everyday for 5 weeks). The concentrations of Mn and other metal elements [Iron (Fe), Copper (Cu), Zinc (Zn), Magnesium (Mg), Calcium (Ca)] in major organs (liver, spleen, kidney, thighbone and iliac bone, cerebral cortex, hippocampus and testes) and blood by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results showed that Mn overexposure significantly increased Mn in most organs, Fe and Zn in liver, Fe and Mg in blood; however decreased Fe, Cu, Zn, Mg and Ca in cortex, Cu and Zn in kidney, Cu and Mg in iliac bone, and Zn in blood. In contrast, PAS-Na treatment restored most changes particularly in cortex. In conclusion, excessive Mn exposure disturbed the balance of other metal elements but PAS-Na post-treatments could restore these alterations. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Shoot Na+ exclusion and increased salinity tolerance engineered by cell type-specific alteration of Na+ transport in Arabidopsis.

    PubMed

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

    2009-07-01

    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.

  19. Uma grade de perfis teóricos para estrelas massivas em transição

    NASA Astrophysics Data System (ADS)

    Nascimento, C. M. P.; Machado, M. A.

    2003-08-01

    Na XXVIII Reunião Anual da Sociedade Astronômica Brasileira (2002) apresentamos uma grade de perfis calculados de acordo com os pontos da trajetória evolutiva de metalicidade solar, Z = 0.02 e taxa de perda de massa () padrão, para estrelas com massa inicial de 25, 40, 60, 85 e 120 massas solares. Estes perfis foram calculados com o auxílio de um código numérico adequado para descrever os ventos de objetos massivos, supondo simetria esférica, estacionaridade e homogeneidade. No presente trabalho, apresentamos a complementação da grade com os perfis teóricos relativos às trajetórias de Z = 0.02 com taxa de perda de massa dobrada em relação a padrão (2´), e de metalicidade Z = 0.008. Para cada ponto das três trajetórias obtemos os perfis teóricos de Ha, Hb, Hg e Hd, e como esperado eles se apresentam em pura emissão, pura absorção ou em P-Cygni. Para valores de taxa de perda de massa muito baixos (~10-7) não há formação de linhas, o que é visto nos primeiros pontos em todas as trajetórias. Em geral, para um mesmo ponto a componente de emissão diminui e a absorção aumenta de Ha para Hd. É verificado que as trajetórias com Z = 0.02 e padrão possuem menos circuitos (loops) do que as com metalicidade Z = 0.02 e 2´ padrão, e seus perfis são, em geral, menos intensos. Em relação a trajetória de Z = 0.008, verifica-se menos circuitos e maior variação em luminosidade, e seus perfis mostram-se em, algumas trajetórias, mais intensos. Verificamos também que, pontos distintos em uma mesma trajetória, apresentam perfis diferentes para valores similares de luminosidade e temperatura efetiva. Sendo assim, uma grade de perfis teóricos parece ser útil para fornecer uma informação preliminar sobre o estágio evolutivo de uma estrela massiva.

  20. Ecotoxicological evaluation of three deicers (NaCl, NaFo, CMA)-effect on terrestrial organisms.

    PubMed

    Robidoux, P Y; Delisle, C E

    2001-02-01

    The use of chemical deicers such as sodium chloride (NaCl) has increased significantly during the past three decades. Deicers induce metal corrosion and alter the physicochemical properties of soils and water. Environmental damage caused by the use of NaCl has prompted government agencies to find alternative deicers. This article presents a comparative ecotoxicological study of three deicers on soil organisms. Sodium formiate (NaFo) and calcium-magnesium acetate (CMA) are the most interesting commercially available deicers based upon their characteristics and potential toxicity. Organisms used in this study were four species of macrophytes (cress (Lepidium sativum), barley (Ordeum vulgare), red fescue grass (Festuca rubra), Kentucky bluegrass (Poa pratensis)) and an invertebrate (Eisenia fetida). Using standardized and modified methods, the relative toxicity of deicers was CMA < NaFo congruent with NaCl. The results demonstrate that these chemicals could have similar impacts in terrestrial environments since similar quantities of NaFo and greater amounts of CMA are necessary to achieve the same efficiency as NaCl. The toxicity of the tested substances was lower in natural composted soil than in artificial substrate (silica or OECD soil), indicating decreased environmental bioavailability. The response of the organisms changed according to endpoint, species, and soil characteristics (artificial substrate as compared to natural organic soil). The most sensitive endpoint measured was macrophyte growth with Kentucky bluegrass being the most sensitive species. Copyright 2001 Academic Press.

  1. Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton

    PubMed Central

    Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

    2012-01-01

    A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root. PMID:22200663

  2. Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles.

    PubMed

    Peckhaus, Andreas; Kiselev, Alexei; Wagner, Robert; Duft, Denis; Leisner, Thomas

    2016-12-28

    Recent laboratory studies indicate that the hydrated form of crystalline NaCl is potentially important for atmospheric processes involving depositional ice nucleation on NaCl dihydrate particles under cirrus cloud conditions. However, recent experimental studies reported a strong discrepancy between the temperature intervals where the efflorescence of NaCl dihydrate has been observed. Here we report the measurements of the volume specific nucleation rate of crystalline NaCl in the aqueous solution droplets of pure NaCl suspended in an electrodynamic balance at constant temperature and humidity in the range from 250 K to 241 K. Based on these measurements, we derive the interfacial energy of crystalline NaCl dihydrate in a supersaturated NaCl solution and determined its temperature dependence. Taking into account both temperature and concentration dependence of nucleation rate coefficients, we explain the difference in the observed fractions of NaCl dihydrate reported in the previous studies. Applying the heterogeneous classical nucleation theory model, we have been able to reproduce the 5 K shift of the NaCl dihydrate efflorescence curve observed for the sea salt aerosol particles, assuming the presence of super-micron solid inclusions (hypothetically gypsum or hemihydrate of CaSO 4 ). These results support the notion that the phase transitions in microscopic droplets of supersaturated solution should be interpreted by accounting for the stochastic nature of homogeneous and heterogeneous nucleation and cannot be understood on the ground of bulk phase diagrams alone.

  3. Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles

    NASA Astrophysics Data System (ADS)

    Peckhaus, Andreas; Kiselev, Alexei; Wagner, Robert; Duft, Denis; Leisner, Thomas

    2016-12-01

    Recent laboratory studies indicate that the hydrated form of crystalline NaCl is potentially important for atmospheric processes involving depositional ice nucleation on NaCl dihydrate particles under cirrus cloud conditions. However, recent experimental studies reported a strong discrepancy between the temperature intervals where the efflorescence of NaCl dihydrate has been observed. Here we report the measurements of the volume specific nucleation rate of crystalline NaCl in the aqueous solution droplets of pure NaCl suspended in an electrodynamic balance at constant temperature and humidity in the range from 250 K to 241 K. Based on these measurements, we derive the interfacial energy of crystalline NaCl dihydrate in a supersaturated NaCl solution and determined its temperature dependence. Taking into account both temperature and concentration dependence of nucleation rate coefficients, we explain the difference in the observed fractions of NaCl dihydrate reported in the previous studies. Applying the heterogeneous classical nucleation theory model, we have been able to reproduce the 5 K shift of the NaCl dihydrate efflorescence curve observed for the sea salt aerosol particles, assuming the presence of super-micron solid inclusions (hypothetically gypsum or hemihydrate of CaSO4). These results support the notion that the phase transitions in microscopic droplets of supersaturated solution should be interpreted by accounting for the stochastic nature of homogeneous and heterogeneous nucleation and cannot be understood on the ground of bulk phase diagrams alone.

  4. Scintillation efficiency measurement of Na recoils in NaI(Tl) below the DAMA/LIBRA energy threshold

    NASA Astrophysics Data System (ADS)

    Xu, Jingke; Shields, Emily; Calaprice, Frank; Westerdale, Shawn; Froborg, Francis; Suerfu, Burkhant; Alexander, Thomas; Aprahamian, Ani; Back, Henning O.; Casarella, Clark; Fang, Xiao; Gupta, Yogesh K.; Ianni, Aldo; Lamere, Edward; Lippincott, W. Hugh; Liu, Qian; Lyons, Stephanie; Siegl, Kevin; Smith, Mallory; Tan, Wanpeng; Kolk, Bryant Vande

    2015-07-01

    The dark matter interpretation of the DAMA modulation signal depends on the NaI(Tl) scintillation efficiency of nuclear recoils. Previous measurements for Na recoils have large discrepancies, especially in the DAMA/LIBRA modulation energy region. We report a quenching effect measurement of Na recoils in NaI(Tl) from 3 to 52 keVnr, covering the whole DAMA/LIBRA energy region for dark matter-Na scattering interpretations. By using a low-energy, pulsed neutron beam, a double time-of-flight technique, and pulse-shape discrimination methods, we obtained the most accurate measurement of this kind for NaI(Tl) to date. The results differ significantly from the DAMA reported values at low energies but fall between the other previous measurements. We present the implications of the new quenching results for the dark matter interpretation of the DAMA modulation signal.

  5. Dynamic polarizabilities and Van der Waals coefficients for alkali atoms Li, Na and alkali dimer molecules Li2, Na2 and NaLi

    NASA Astrophysics Data System (ADS)

    Mérawa, M.; Dargelos, A.

    1998-07-01

    The present paper gives an account of investigations of the polarizability of the alkali atoms Li, Na, diatomics homonuclear and heteronuclear Li2, Na2 and NaLi at SCF (Self Consistent Field) level of approximation and at correlated level, using a time Time-Dependent Gauge Invariant method (TDGI). Our static polarizability values agree with the best experimental and theoretical determinations. The Van der Waals C6 coefficients for the atom-atom, atom-dimer and dimer-dimer interactions have been evaluated. Les polarisabilités des atomes alcalins Li, Na, et des molécules diatomiques homonucléaires et hétéronucléaire Li2, Na2 et NaLi, ont été calculées au niveau SCF (Self Consistent Field) et au niveau corrélé à partir d'une méthode invariante de jauge dépendante du temps(TDGI). Nos valeurs des polarisabilités statiques sont en accord avec les meilleurs déterminations expérimentales et théoriques. Les coefficients C6 de Van de Waals pour les interactions atome-atome, atome-dimère et dimère-dimère ont également été évalués.

  6. 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 31Π in NaK or to the 53Π 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.

  7. Projeto do sistema anti-ressonante da fiação dos transdutores para o detector Mario Schenberg

    NASA Astrophysics Data System (ADS)

    Vieira, S. J.., Jr.; Melo, J. L.

    2003-08-01

    O detector de ondas gravitacionais Mario Schenberg está sendo projetado e construído pelo grupo Gráviton. Sua construção está ocorrendo no Laboratório de Estado Sólido e Baixas Temperaturas (LESBT) da Universidade de São Paulo, na cidade de São Paulo. Esse detector possui uma massa ressonante esférica de cobre-alumínio, com 65 cm de diâmetro, pesando aproximadamente 1150 Kg, suspensa por um sistema de isolamento vibracional, que se encontra em fase de testes preliminares. A real eficácia desse sistema, entretanto, só poderá ser comprovada quando o detector estiver aparelhado com, pelo menos, um transdutor eletromecânico de altíssima sensibilidade acoplado à massa ressonante. Neste momento, não só este sistema de isolamento vibracional será posto em teste, como o do projeto da fiação que transporta os sinais de microondas até os transdutores e destes para a pré-amplificação. Apesar dessa fiação ter sido projetada para não apresentar nenhum contato com a superfície esférica da antena, de maneira a não haver nenhuma transmissão de ruído vibracional do laboratório para esta, deve-se minimizar o ruído microfônico produzido nessa fiação por oscilações mecânicas, uma vez que ela não utiliza nenhum sistema de isolamento vibracional. Com o intuito de resolver este problema, projetamos uma estrutura, formada por pequenos cilindros conectados por barras, a qual não terá nenhuma ressonância mecânica na faixa de freqüências de interesse para detecção (3000 - 3400 Hz). Desta forma, as vibrações nessa faixa não serão amplificadas. O projeto foi feito usando iterativamente, de maneira a otimizar os resultados obtidos, o programa de elementos finitos Msc/Nastran. Através de simulações feitas neste programa, determinamos os parâmetros geométricos ideais a serem utilizados, os quais proporcionam a maior região espectral de interesse livre de ressonâncias.

  8. Scintillation efficiency measurement of Na recoils in NaI(Tl) below the DAMA/LIBRA energy threshold

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Jingke; Shields, Emily; Calaprice, Frank

    2015-07-01

    The dark matter interpretation of the DAMA modulation signal depends on the NaI(Tl) scintillation efficiency of nuclear recoils. Previous measurements for Na recoils have large discrepancies, especially in the DAMA/LIBRA modulation energy region. We report a quenching effect measurement of Na recoils in NaI(Tl) from 3 to 52 keVnr, covering the whole DAMA/LIBRA energy region for dark matter-Na scattering interpretations. By using a low-energy, pulsed neutron beam, a double time-of-flight technique, and pulse-shape discrimination methods, we obtained the most accurate measurement of this kind for NaI(Tl) to date. The results differ significantly from the DAMA reported values at low energies butmore » fall between the other previous measurements. We present the implications of the new quenching results for the dark matter interpretation of the DAMA modulation signal.« less

  9. Studies of rotationally inelastic collisions of NaK and NaCs with Ar and He perturbers

    NASA Astrophysics Data System (ADS)

    Jones, J.; Faust, C.; Richter, K.; Wolfe, C. M.; Ashman, S.; Malenda, R. F.; Weiser, P.; Carlus, S.; Fragale, A.; Hickman, A. P.; Huennekens, J.

    2013-05-01

    We report studies of rotationally inelastic collisions of Ar and He atoms with the molecules NaK and NaCs prepared in various ro-vibrational levels of the A1Σ+ electronic state. We use laser induced fluorescence (LIF) and polarization labeling (PL) spectroscopy in a pump-probe, two step excitation process. The pump excites the molecule to a ro-vibrational level (v , J) in the A state. The probe laser is scanned over transitions to the 31 Π state in NaK or the 53 Π state in NaCs. In addition to strong direct lines, we observe weak satellite lines that arise from collision-induced transitions of the A state level (v , J) to (v , J + ΔJ) . The ratio of intensities of the satellite line to the direct line in LIF and PL yields information about population and orientation transfer. Preliminary results show a strong propensity for collisions with ΔJ =even for NaK; the propensity is larger for He than for Ar. Collisions of NaCs with He show a similar propensity, but collisions of NaCs with Ar do not. Theoretical calculations are also underway. For He-NaK, we have completed potential surface calculations using GAMESS and coupled channel scattering calculations of rotational energy transfer and transfer of orientation. Work supported by NSF and XSEDE.

  10. Clues to NaCN formation

    NASA Astrophysics Data System (ADS)

    Quintana-Lacaci, G.; Cernicharo, J.; Velilla Prieto, L.; Agúndez, M.; Castro-Carrizo, A.; Fonfría, J. P.; Massalkhi, S.; Pardo, J. R.

    2017-11-01

    Context. ALMA is providing us essential information on where certain molecules form. Observing where these molecules emission arises from, the physical conditions of the gas, and how this relates with the presence of other species allows us to understand the formation of many species, and to significantly improve our knowledge of the chemistry that occurs in the space. Aims: We studied the molecular distribution of NaCN around IRC +10216, a molecule detected previously, but whose origin is not clear. High angular resolution maps allow us to model the abundance distribution of this molecule and check suggested formation paths. Methods: We modeled the emission of NaCN assuming local thermal equilibrium (LTE) conditions. These profiles were fitted to azimuthal averaged intensity profiles to obtain an abundance distribution of NaCN. Results: We found that the presence of NaCN seems compatible with the presence of CN, probably as a result of the photodissociation of HCN, in the inner layers of the ejecta of IRC +10216. However, similar as for CH3CN, current photochemical models fail to reproduce this CN reservoir. We also found that the abundance peak of NaCN appears at a radius of 3 × 1015 cm, approximately where the abundance of NaCl, suggested to be the parent species, starts to decay. However, the abundance ratio shows that the NaCl abundance is lower than that obtained for NaCN. We expect that the LTE assumption might result in NaCN abundances higher than the real ones. Updated photochemical models, collisional rates, and reaction rates are essential to determine the possible paths of the NaCN formation. Based on observations carried out with ALMA and the IRAM 30 m Telescope. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. IRAM is supported by INSU/CNRS (France

  11. Study on Na layer response to geomagnetic activities based on Odin/OSIRIS Na density data

    NASA Astrophysics Data System (ADS)

    Tsuda, Takuo; Nakamura, Takuji; Hedin, Jonas; Gumbel, Jorg; Hosokawa, Keisuke; Ejiri, Mitsumu K.; Nishiyama, Takanori; Takahashi, Toru

    2016-07-01

    The Na layer is normally distributed from 80 to 110 km, and the height range is corresponding to the ionospheric D and E region. In the polar region, the energetic particles precipitating from the magnetosphere can often penetrate into the E region and even into the D region. Thus, the influence of the energetic particles to the Na layer is one of interests in the aspect of the atmospheric composition change accompanied with the auroral activity. There are several previous studies in this issue. For example, recently, we have reported an initial result on a clear relationship between the electron density increase (due to the energetic particles) and the Na density decrease from observational data sets obtained by Na lidar, EISCAT VHF radar, and optical instruments at Tromsoe, Norway on 24-25 January 2012. However, all of the previous studies had been carried out based on case studies by ground-based lidar observations. In this study, we have performed, for the first time, statistical analysis using Na density data from 2004 to 2009 obtained with the Optical Spectrograph and InfraRed Imager System (OSIRIS) onboard Odin satellite. In the presentation, we will show relationship between the Na density and geomagnetic activities, and its latitudinal variation. Based on these results, the Na layer response to the energetic particles will be discussed.

  12. 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.%.

  13. Unidirectional Flux Balance of Monovalent Ions in Cells with Na/Na and Li/Na Exchange: Experimental and Computational Studies on Lymphoid U937 Cells

    PubMed Central

    Vereninov, Igor A.; Yurinskaya, Valentina E.; Model, Michael A.; Vereninov, Alexey A.

    2016-01-01

    Monovalent ion traffic across the cell membrane occurs via various pathways. Evaluation of individual fluxes in whole cell is hampered by their strong interdependence. This difficulty can be overcome by computational analysis of the whole cell flux balance. However, the previous computational studies disregarded ion movement of the self-exchange type. We have taken this exchange into account. The developed software allows determination of unidirectional fluxes of all monovalent ions via the major pathways both under the balanced state and during transient processes. We show how the problem of finding the rate coefficients can be solved by measurement of monovalent ion concentrations and some of the fluxes. Interdependence of fluxes due to the mandatory conditions of electroneutrality and osmotic balance and due to specific effects can be discriminated, enabling one to identify specific changes in ion transfer machinery under varied conditions. To test the effectiveness of the developed approach we made use of the fact that Li/Na exchange is known to be an analogue of the coupled Na/Na exchange. Thus, we compared the predicted and experimental data obtained on U937 cells under varied Li+ concentrations and following inhibition of the sodium pump with ouabain. We found that the coupled Na/Na exchange in U937 cells comprises a significant portion of the entire Na+ turnover. The data showed that the loading of the sodium pump by Li/Na exchange involved in the secondary active Li+ transport at 1–10 mM external Li+ is small. This result may be extrapolated to similar Li+ and Na+ flux relationships in erythrocytes and other cells in patients treated with Li+ in therapeutic doses. The developed computational approach is applicable for studying various cells and can be useful in education for demonstrating the effects of individual transporters and channels on ion gradients, cell water content and membrane potential. PMID:27159324

  14. Jahn–Teller Assisted Na Diffusion for High Performance Na Ion Batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Xin; Wang, Yan; Wu, Di

    2016-08-30

    Na energy storage technology is strategically attractive for large scale applications such as grid energy storage. Here, we show in this paper that there is a clear relation between the Jahn$-$Teller activity of a transition metal ion at the end of charge and the mobility of Na in a cathode material. This is particularly important as mobility at the end of charge limits the capacity of current materials. Consequently, by using this classical piece of physics in the battery world, it is possible to create higher capacity Na-cathode materials. Even more exciting is that the ideal element to impart thismore » effect on cathodes is Fe, which is the least expensive of the transition metal oxides and can therefore enable low cost cathode materials.« less

  15. Identificação de variáveis cataclísmicas eruptivas na direção do bojo galáctico e Nuvens de Magalhães usando dados do OGLE

    NASA Astrophysics Data System (ADS)

    Cieslinski, D.; Diaz, M. P.; Mennickent, R.; Pietrzyski, G.

    2003-08-01

    Na década de 90 iniciaram-se vários programas para a pesquisa de matéria escura na Galáxia usando o efeito de microlentes gravitacionais. Entre os projetos mais bem conhecidos podemos mencionar o OGLE (Optical Gravitational Lensing Experiment) e o MACHO (MAssive Compact Halo Objects). A estratégia usada por eles consiste em fazer fotometria de banda larga (normalmente B, R e I) de um grande número de estrelas (dezenas de milhões) tão freqüentemente quanto possí vel e por longos perí odos de tempo (anos). Uma tal sistemática de observação, além de descobrir inúmeras lentes gravitacionais, é também muito apropriada para a descoberta de estrelas variáveis. De fato, inúmeras novas variáveis de vários tipos foram descobertas como subproduto. Exemplos podem ser encontrados nos endereços http://bulge.princeton.edu/~ogle/ e http://wwwmacho.mcmaster.ca/. As variáveis cataclí smicas eruptivas (novas clássicas, novas recorrentes e novas anãs) são objetos que apresentam variabilidade de grande amplitude com escalas de tempo de dias a centenas de dias e, por esta razão, devem ter sido detectadas em grande número nestes "surveys". Para testar esta possibilidade nós procuramos nos dados do OGLE por tais sistemas e o presente trabalho mostra os resultados desta pesquisa. Os objetos foram selecionados entre as variáveis detectadas usando a amplitude de variação de brilho como critério principal. Este critério forneceu 13756 objetos, sendo 2169 na direção da Grande Nuvem de Magalhães, 1162 na direção da Pequena Nuvem de Magalhães e o restante na direção do Bojo Galáctico. A análise foi feita inspecionando-se visualmente cada curva de luz por erupções com as características acima mencionadas. Os resultados obtidos podem ser sumarizados como: descoberta de duas novas clássicas e 33 novas anãs. Além disso, pode-se mencionar a identificação de candidatas a outros tipos de variáveis como: estrelas simbióticas, RV Tauri, R Coronae

  16. Controlled phase stability of highly Na-active triclinic structure in nanoscale high-voltage Na2-2xCo1+xP2O7 cathode for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Song, Hee Jo; Kim, Jae-Chan; Dar, Mushtaq Ahmad; Kim, Dong-Wan

    2018-02-01

    With the increasing demand for high energy density in energy-storage systems, a high-voltage cathode is essential in rechargeable Li-ion and Na-ion batteries. The operating voltage of a triclinic-polymorph Na2CoP2O7, also known as the rose form, is above 4.0 V (vs. Na/Na+), which is relatively high compared to that of other cathode materials. Thus, it can be employed as a potential high-voltage cathode material in Na-ion batteries. However, it is difficult to synthesize a pure rose phase because of its low phase stability, thus limiting its use in high-voltage applications. Herein, compositional-engineered, rose-phase Na2-2xCo1+xP2O7/C (x = 0, 0.1 and 0.2) nanopowder are prepared using a wet-chemical method. The Na2-2xCo1+xP2O7/C cathode shows high electrochemical reactivity with Na ions at 4.0 V, delivering high capacity and high energy density.

  17. Electrogenic Na+/Ca2+ Exchange

    PubMed Central

    Danaceau, Jonathan P.; Lucero, Mary T.

    2000-01-01

    Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction. PMID:10828249

  18. 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

  19. Zero-gravity growth of NaF-NaCl eutectics in the NASA Skylab program

    NASA Technical Reports Server (NTRS)

    Yue, A. S.; Allen, F. G.; Yu, J. G.

    1976-01-01

    Continuous and discontinuous NaF fibers, embedded in a NaCl matrix, were produced in space and on earth. The production of continuous fibers in a eutectic mixture is attributed to the absence of convection current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and earth-grown ingots were made with a light microscope and a spectrometer. It is shown that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of NaF fibers along the ingot axis. A new concept is advanced to explain the phenomenon of transmittance versus far infrared wavelength of the directionally solidified NaCl-NaF eutectic in terms of the two-dimensional Bragg Scattering and the polarization effect of Rayleigh scattering. This concept can be applied to other eutectic systems as long as the index of refraction of the matrix over a range of wavelengths is known. Experimental data are in agreement with the theoretical prediction.

  20. Light-driven Na + pump from Gillisia limnaea: A high-affinity Na + binding site is formed transiently in the photocycle

    DOE PAGES

    Balashov, Sergei P.; Imasheva, Eleonora S.; Dioumaev, Andrei K.; ...

    2014-11-06

    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 differencesmore » 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 μM 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. Furthermore, 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.« less

  1. RNA adducts with Na 2SeO 4 and Na 2SeO 3 - Stability and structural features

    NASA Astrophysics Data System (ADS)

    Nafisi, Shohreh; Manouchehri, Firouzeh; Montazeri, Maryam

    2011-12-01

    Selenium compounds are widely available in dietary supplements and have been extensively studied for their antioxidant and anticancer properties. Low blood Se levels were found to be associated with an increased incidence and mortality from various types of cancers. Although many in vivo and clinical trials have been conducted using these compounds, their biochemical and chemical mechanisms of efficacy are the focus of much current research. This study was designed to examine the interaction of Na 2SeO 4 and Na 2SeO 3 with RNA in aqueous solution at physiological conditions, using a constant RNA concentration (6.25 mM) and various sodium selenate and sodium selenite/polynucleotide (phosphate) ratios of 1/80, 1/40, 1/20, 1/10, 1/5, 1/2 and 1/1. Fourier transform infrared, UV-Visible spectroscopic methods were used to determine the drug binding modes, the binding constants, and the stability of Na 2SeO 4 and Na 2SeO 3-RNA complexes in aqueous solution. Spectroscopic evidence showed that Na 2SeO 4 and Na 2SeO 3 bind to the major and minor grooves of RNA ( via G, A and U bases) with some degree of the Se-phosphate (PO 2) interaction for both compounds with overall binding constants of K(Na 2SeO 4-RNA) = 8.34 × 10 3 and K(Na 2SeO 3-RNA) = 4.57 × 10 3 M -1. The order of selenium salts-biopolymer stability was Na 2SeO 4-RNA > Na 2SeO 3-RNA. RNA aggregations occurred at higher selenium concentrations. No biopolymer conformational changes were observed upon Na 2SeO 4 and Na 2SeO 3 interactions, while RNA remains in the A-family structure.

  2. Na Diffusion in Quasi One-Dimensional Ion Conductor NaMn2O4 Observed by μ+SR

    NASA Astrophysics Data System (ADS)

    Umegaki, Izumi; Nozaki, Hiroshi; Harada, Masashi; Månsson, Martin; Sakurai, Hiroya; Kawasaki, Ikuto; Watanabe, Isao; Sugiyama, Jun

    A quasi one-dimensional (1D) compound, NaMn2O4, in which Mn2O4 zigzag chains form a 1D channel along the b-axis and Na ions locate at the center of the channel, is thought to be a good Na ionic conductor. In order to study Na-ion diffusion, we have measured μ+SR spectra using a powder sample in the temperature range between 100 and 500 K. A diffusive behavior was clearly observed above 325 K. Assuming a thermal activate process for jump diffusion of Na-ion between two nearest neighboring sites, a self diffusion coefficient of Na ion (DNa) and its activation energy (Ea) were estimated as DNa = (3.1 ± 0.2) × 10 - 11 cm2/s at 350 K and Ea = 180(9) meV.

  3. Spatiotemporal analysis of air conditions as a tool for the environmental management of a show cave (Cueva del Agua, Spain)

    NASA Astrophysics Data System (ADS)

    Fernandez-Cortes, A.; Calaforra, J. M.; Sanchez-Martos, F.

    We recorded the air temperature and carbon dioxide concentration within the Cueva del Agua, a cave in Spain, under natural conditions prior to the cave being opened to tourists. Geostatistical tools are useful techniques for characterizing microclimate parameters with the aim of adopting measures to ensure the conservation and sound environmental management of tourist caves. We modelled the spatial distribution of these microclimatic parameters over an annual cycle using iterative residual kriging, revealing the stratification of air related to the cave's topography. Replenishment of the cave air is activated by convective circulation that accompanies the development of inversions in the thermal gradient of the air. Comparison of the spatial distribution of each microclimatic parameter over time enables us to characterize the exchange of air between the cave interior and the outside, as well as identify potential areas that could be opened to tourists and determine suitable visiting schedules.

  4. High-Performance Na-O2 Batteries Enabled by Oriented NaO2 Nanowires as Discharge Products.

    PubMed

    Khajehbashi, S Mohammad B; Xu, Lin; Zhang, Guobin; Tan, Shuangshuang; Zhao, Yan; Wang, Lai-Sen; Li, Jiantao; Luo, Wen; Peng, Dong-Liang; Mai, Liqiang

    2018-06-13

    Na-O 2 batteries are emerging rechargeable batteries due to their high theoretical energy density and abundant resources, but they suffer from sluggish kinetics due to the formation of large-size discharge products with cubic or irregular particle shapes. Here, we report the unique growth of discharge products of NaO 2 nanowires inside Na-O 2 batteries that significantly boosts the performance of Na-O 2 batteries. For this purpose, a high-spin Co 3 O 4 electrocatalyst was synthesized via the high-temperature oxidation of pure cobalt nanoparticles in an external magnetic field. The discharge products of NaO 2 nanowires are 10-20 nm in diameter and ∼10 μm in length, characteristics that provide facile pathways for electron and ion transfer. With these nanowires, Na-O 2 batteries have surpassed 400 cycles with a fixed capacity of 1000 mA h g -1 , an ultra-low over-potential of ∼60 mV during charging, and near-zero over-potential during discharging. This strategy not only provides a unique way to control the morphology of discharge products to achieve high-performance Na-O 2 batteries but also opens up the opportunity to explore growing nanowires in novel conditions.

  5. Silver segregation in Ag/a-C nanocomposite coatings for potential application as antibacterial surfaces

    NASA Astrophysics Data System (ADS)

    Manninen, Noora Kristiina Alves de Sousa

    O desenvolvimento de superficies antibacterianas representa um desafio atual em diferentes aplicacoes industriais, nomeadamente, dispositivos medicos, embalagens alimentares, texteis e sistemas de tratamento de agua. A maioria das bacterias existe em biofilmes que aderem fortemente a diferentes tipos de superficies uma vez que esta adesao representa um mecanismo estrategico de sobrevivencia. O fenomeno da adesao e colonizacao microbiana resulta na falha de diferentes dispositivos e componentes utilizados nas aplicacoes acima mencionadas, tendo como consequencia perdas economicas elevadas e representando tambem um problema de saude publica quando se tratam de aplicacoes como dispositivos medicos ou embalagens alimentares. Neste sentido, ao longo das ultimas decadas o desenvolvimento de superficies antibacterianas tem sido considerada uma estrategia emergente no desenvolvimento de materiais mais eficientes a serem aplicados em diferentes sectores. O objetivo da presente tese consiste no desenvolvimento e caracterizacao de revestimentos nanocompositos multifuncionais baseados em revestimentos de carbono amorfo dopado com nanoparticulas de prata (Ag/a-C) para potencial aplicacao em superficies antibacterianas. A Ag e atualmente considerada como o agente bactericida mais promissor e eficiente, sendo que as nanoparticulas de prata representam o material mais comercializado na area da nanotecnologia. A estrategia de modificacao superficial com revestimentos baseados em carbono amorfo (a-C) tem-se tornado popular do ponto de vista industrial essencialmente, devido entre outras propriedades, a sua resistencia ao desgaste tribologico excecional, que permite combinar uma elevada dureza com um baixo coeficiente de atrito, elevada estabilidade quimica, resistencia a corrosao e biocompatibilidade em diferentes aplicacoes biomedicas. Na atualidade os revestimentos de a-C sao utilizados em diferentes aplicacoes industriais nomeadamente dispositivos medicos, laminas de barbear e

  6. Determinação da composição química em nebulosas planetárias na direção do anticentro galáctico

    NASA Astrophysics Data System (ADS)

    Costa, R. D. D.; Uchida, M. M. M.; Maciel, W. J.

    2003-08-01

    Existe um gradiente radial de abundâncias no disco galáctico, cujo comportamento é razoavelmente bem conhecido para distâncias galactocêntricas entre 3 e 10 kpc. Foi obtido a partir de resultados derivados de nebulosas planetárias, regiões HII e estrelas, como as estrelas quentes de tipo O, B e aglomerados abertos. Com o objetivo de investigar o comportamento deste gradiente radial na região externa do disco, conhecida como anticentro galáctico, reportamos aqui os resultados finais da análise de uma amostra de nebulosas planetárias na direção do anticentro, observadas no LNA e no ESO entre 1995 e 2000. O uso de nebulosas planetárias permite o cálculo das abundâncias de elementos traçadores da evolução química do disco como oxigênio, argônio e neônio com o uso de técnicas de espectroscopia nebular. Os resultados indicam uma distribuição de abundâncias distinta daquela encontrada na vizinhança solar, mostrando que o gradiente radial diminui sensivelmente para distâncias galactocêntricas maiores que 10 kpc. Este resultado está de acordo com os mais recentes modelos de evolução química do disco, que prevêem uma diminuição ou mesmo um desaparecimento do gradiente radial no bordo externo do disco galáctico. (FAPESP/CNPq)

  7. Usina de ciências: um espaço pedagógico para aprendizagens múltiplas

    NASA Astrophysics Data System (ADS)

    Martin, V. A. F.; Poppe, P. C. R.; Orrico, A. C. P.; Pereira, M. G.

    2003-08-01

    Entendemos que o Ensino de Astronomia é especialmente apropriado para motivar os alunos e aprofundar conteúdos em diversas áreas do conhecimento, pois envolve temas ligados à Física, Matemática, Química, Computação, Tratamento de Imagens e Instrumentação de Alta Precisão, além daqueles pertinentes as áreas de Geografia, História e Antropologia. Contudo, apesar do caráter interdisciplinar que esta ciência possui, a realidade atual é que a maioria dos professores em sala de aula não foram devidamente capacitados, durante o período de formação acadêmica, para ministrar conteúdos de Astronomia nos atuais Ensinos Fundamental e Médio. Neste trabalho, discutiremos de maneira ampla, num primeiro momento, a realidade do atual ensino de ciências praticado no Estado da Bahia, apontando por dependência administrativa, o crescimento e a redução do número de escolas, da taxa de analfabetismo por faixa etária, da escolarização, do atendimento, da aprovação, reprovação e abandono, de equipamentos e laboratórios e o grau de formação dos nossos atuais professores em pleno exercício de atividade docente. Num segundo momento, discutiremos o papel do Observatório Astronômico Antares/UEFS dentro desse contexto, ou seja, suas ações implementadas ao longo dos últimos anos e em particular, o recente projeto de extensão Ensino e Difusão de Astronomia, financiado pela Fundação Vitae, que procura traduzir no lúdico, no brincar de ciências, um espaço pedagógico para aprendizagens múltiplas. Neste, o papel do professor multiplicador associado ao laboratório de kits didáticos, de fácil construção e manipulação (alguns dos quais serão mostrados), perfazem os principais veículos para o desenvolvimento de conhecimentos, atitudes, habilidades e valores que preparam os nossos alunos para a carreira técnico-científica e para sua participação crítica e criativa na Sociedade.

  8. 24Mg(p, α) 21Na reaction study for spectroscopy of 21Na

    DOE PAGES

    Cha, S. M.; Chae, K. Y.; Kim, A.; ...

    2015-11-03

    The Mg-24(p, alpha)Na-21 reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain the spins and parities of the energy levels in Na-21 for the astrophysically important F-17(alpha, p)Ne-20 reaction rate calculation. 31-MeV proton beams from the 25-MV tandem accelerator and enriched Mg-24 solid targets were used. When recoiling He-4 particles from the Mg-24(p, alpha)Na-21 reaction we used a highly segmented silicon detector array to detect them; it measured the yields of He-4 particles over a range of angles simultaneously. A observed a new level at 6661 ± 5 keVmore » in the present work. The extracted angular distributions for the first four levels of Na-21 and the results from distorted wave Born approximation (DWBA) calculations were compared to verify and extract the angular momentum transfer.« less

  9. Insight to the Thermal Decomposition and Hydrogen Desorption Behaviors of NaNH2-NaBH4 Hydrogen Storage Composite.

    PubMed

    Pei, Ziwei; Bai, Ying; Wang, Yue; Wu, Feng; Wu, Chuan

    2017-09-20

    The lightweight compound material NaNH 2 -NaBH 4 is regarded as a promising hydrogen storage composite due to the high hydrogen density. Mechanical ball milling was employed to synthesize the composite NaNH 2 -NaBH 4 (2/1 molar ratio), and the samples were investigated utilizing thermogravimetric-differential thermal analysis-mass spectroscopy (TG-DTA-MS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. The full-spectrum test (range of the ratio of mass to charge: 0-200) shows that the released gaseous species contain H 2 , NH 3 , B 2 H 6 , and N 2 in the heating process from room temperature to 400 °C, and possibly the impurity gas B 6 H 12 also exists. The TG/DTA analyses show that the composite NaNH 2 -NaBH 4 (2/1 molar ratio) is conductive to generate hydrogen so that the dehydrogenation process can be finished before 400 °C. Moreover, the thermal decomposition process from 200 to 400 °C involves two-step dehydrogenation reactions: (1) Na 3 (NH 2 ) 2 BH 4 hydride decomposes into Na 3 BN 2 and H 2 (200-350 °C); (2) remaining Na 3 (NH 2 ) 2 BH 4 reacts with NaBH 4 and Na 3 BN 2 , generating Na, BN, NH 3 , N 2 , and H 2 (350-400 °C). The better mechanism understanding of the thermal decomposition pathway lays a foundation for tailoring the hydrogen storage performance of the composite complex hydrides system.

  10. Sodium channel diversity in the vestibular ganglion: NaV1.5, NaV1.8, and tetrodotoxin-sensitive currents

    PubMed Central

    2016-01-01

    Firing patterns differ between subpopulations of vestibular primary afferent neurons. The role of sodium (NaV) channels in this diversity has not been investigated because NaV currents in rodent vestibular ganglion neurons (VGNs) were reported to be homogeneous, with the voltage dependence and tetrodotoxin (TTX) sensitivity of most neuronal NaV channels. RT-PCR experiments, however, indicated expression of diverse NaV channel subunits in the vestibular ganglion, motivating a closer look. Whole cell recordings from acutely dissociated postnatal VGNs confirmed that nearly all neurons expressed NaV currents that are TTX-sensitive and have activation midpoints between −30 and −40 mV. In addition, however, many VGNs expressed one of two other NaV currents. Some VGNs had a small current with properties consistent with NaV1.5 channels: low TTX sensitivity, sensitivity to divalent cation block, and a relatively negative voltage range, and some VGNs showed NaV1.5-like immunoreactivity. Other VGNs had a current with the properties of NaV1.8 channels: high TTX resistance, slow time course, and a relatively depolarized voltage range. In two NaV1.8 reporter lines, subsets of VGNs were labeled. VGNs with NaV1.8-like TTX-resistant current also differed from other VGNs in the voltage dependence of their TTX-sensitive currents and in the voltage threshold for spiking and action potential shape. Regulated expression of NaV channels in primary afferent neurons is likely to selectively affect firing properties that contribute to the encoding of vestibular stimuli. PMID:26936982

  11. Enhancement of the sulfur capture capacity of limestones by the addition of Na2CO3 and NaCl.

    PubMed

    Laursen, K; Grace, J R; Lim, C J

    2001-11-01

    The ability of Na2CO3 and NaCl to enhance the sulfur capture capacity of three limestones was evaluated via fixed-bed calcination and sulfation experiments. The tested limestones represent three different sulfation morphologies: unreacted-core, network, and uniformly sulfated. Treatment with aqueous or powdered Na2CO3 significantly increased the Ca-utilization for two stones which normally sulfate in an unreacted-core pattern (20% to 45%) and network pattern (33% to 49%). The increase was lower for the uniformly sulfated stone (44% to 48%). Na2CO3 treatment increased the number of macropores leading to uniform sulfation of all particles, nearly eliminating the normal strong dependence of utilization on limestone type and particle size. The effect of Na2CO3 is believed to be associated with formation of a eutectic melt which enhances ionic diffusion and accelerates molecular rearrangement of the CaO. Treatment with aqueous NaCl solution caused a decrease in utilization, probably due to formation of large grains and plugging of pores caused by formation of a large amount of eutectic melt. The effect of Na2CO3 is less sensitive than that of NaCl to the amount added and the combustion environment (temperature and gas composition). In addition, Na2CO3 neither promotes corrosion nor forms chlorinated byproducts, which are main concerns associated with NaCl. Thus, Na2CO3 appears to have significant advantages over NaCl for enhancement of limestone sulfur capture capacity in fluidized-bed combustors.

  12. Concentration dependence of Li+/Na+ diffusion in manganese hexacyanoferrates

    NASA Astrophysics Data System (ADS)

    Takachi, Masamitsu; Fukuzumi, Yuya; Moritomo, Yutaka

    2016-06-01

    Manganese hexacyanoferrates (Mn-HCFs) with a jungle-gym-type structure are promising cathode materials for Li+/Na+ secondary batteries (LIBs/SIBs). Here, we investigated the diffusion constants D Li/D Na of Li+/Na+ against the Li+/Na+ concentration x Na/x Li and temperature (T) of A 1.32Mn[Fe(CN)6]0.833.6H2O (A = Li and Na). We evaluated the activation energy E\\text{a}\\text{Li}/E\\text{a}\\text{Na} of D Li/D Na against x Na/x Li. We found that E\\text{a}\\text{Na} steeply increases with x Na from 0.41 eV at x Na = 0.69 to 0.7 eV at 1.1. The increase in E\\text{a}\\text{Na} is ascribed to the occupancy effect of the Na+ site. The increase in E\\text{a}\\text{Li} is suppressed, probably because the number of Li+ sites is three times that of Na+ sites.

  13. Carbon dioxide sequestration using NaHSO4 and NaOH: A dissolution and carbonation optimisation study.

    PubMed

    Sanna, Aimaro; Steel, Luc; Maroto-Valer, M Mercedes

    2017-03-15

    The use of NaHSO 4 to leach out Mg fromlizardite-rich serpentinite (in form of MgSO 4 ) and the carbonation of CO 2 (captured in form of Na 2 CO 3 using NaOH) to form MgCO 3 and Na 2 SO 4 was investigated. Unlike ammonium sulphate, sodium sulphate can be separated via precipitation during the recycling step avoiding energy intensive evaporation process required in NH 4 -based processes. To determine the effectiveness of the NaHSO 4 /NaOH process when applied to lizardite, the optimisation of the dissolution and carbonation steps were performed using a UK lizardite-rich serpentine. Temperature, solid/liquid ratio, particle size, concentration and molar ratio were evaluated. An optimal dissolution efficiency of 69.6% was achieved over 3 h at 100 °C using 1.4 M sodium bisulphate and 50 g/l serpentine with particle size 75-150 μm. An optimal carbonation efficiency of 95.4% was achieved over 30 min at 90 °C and 1:1 magnesium:sodium carbonate molar ratio using non-synthesised solution. The CO 2 sequestration capacity was 223.6 g carbon dioxide/kg serpentine (66.4% in terms of Mg bonded to hydromagnesite), which is comparable with those obtained using ammonium based processes. Therefore, lizardite-rich serpentinites represent a valuable resource for the NaHSO 4 /NaOH based pH swing mineralisation process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

    PubMed

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Adsorption and Formation of Small Na Clusters on Pristine and Double-Vacancy Graphene for Anodes of Na-Ion Batteries.

    PubMed

    Liang, Zhicong; Fan, Xiaofeng; Zheng, Weitao; Singh, David J

    2017-05-24

    Layered carbon is a likely anode material for Na-ion batteries (NIBs). Graphitic carbon has a low capacity of approximately 35 (mA h)/g due to the formation of NaC 64 . Using first-principles methods including van der Waals interactions, we analyze the adsorption of Na ions and clusters on graphene in the context of anodes. The interaction between Na ions and graphene is found to be weak. Small Na clusters are not stable on the surface of pristine graphene in the electrochemical environment of NIBs. However, we find that Na ions and clusters can be stored effectively on defected graphene that has double vacancies. In addition, the adsorption energy of small Na clusters near a double vacancy is found to decrease with increasing cluster size. With high concentrations of vacancies the capacity of Na on defective graphene is found to be as much as 10-30 times higher than that of graphitic carbon.

  16. 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

  17. 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%.

  18. Integrated measures for preservation, restoration and improvement of the environmental conditions of the Lagoon Olho d'Agua basin.

    PubMed

    Florencio, L; Kato, M T; de Lima, E S

    2001-06-01

    The Lagoon Olho d'Agua in Pernambuco State, Northeast Brazil has received increasing environmental concern due to significant stress from pollution in the catchment. The existing environmental problems are the result of great pressure from a broad range of human activities, especially in the last 10 years. Serious pollution exists mainly from some industrial and urban activities, which increased intensively after the eighties. There is a strong social and economical pressure for housing and construction near the lagoon, due to the available land nearby beaches and estuarine zone, and recently by growing tourism activities. Uncontrolled land use by low-income communities and the pressure for construction by developers have led to landfilling and to deterioration of water quality in the lagoon catchment. Improvement of the environmental conditions in the catchment needs integrated measures. Guidelines and some specific actions involving several institutions have been established and refer to sanitation and urban infrastructure as the main priorities. A main target is the construction of low-cost sewage system with smaller and decentralised treatment plants.

  19. Interaction of NaOH solutions with silica surfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

    Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

  20. Interaction of NaOH solutions with silica surfaces

    DOE PAGES

    Rimsza, Jessica M.; Jones, Reese E.; Criscenti, Louise J.

    2018-01-16

    Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate,more » and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications for the stability of silica surfaces.« less

  1. Superoxide reaction with tyrosyl radicals generates para-hydroperoxy and para-hydroxy derivatives of tyrosine.

    PubMed

    Möller, Matías N; Hatch, Duane M; Kim, Hye-Young H; Porter, Ned A

    2012-10-10

    Tyrosine-derived hydroperoxides are formed in peptides and proteins exposed to enzymatic or cellular sources of superoxide and oxidizing species as a result of the nearly diffusion-limited reaction between tyrosyl radical and superoxide. However, the structure of these products, which informs their reactivity in biology, has not been unequivocally established. We report here the complete characterization of the products formed in the addition of superoxide, generated from xanthine oxidase, to several peptide-derived tyrosyl radicals, formed from horseradish peroxidase. RP-HPLC, LC-MS, and NMR experiments indicate that the primary stable products of superoxide addition to tyrosyl radical are para-hydroperoxide derivatives (para relative to the position of the OH in tyrosine) that can be reduced to the corresponding para-alcohol. In the case of glycyl-tyrosine, a stable 3-(1-hydroperoxy-4-oxocyclohexa-2,5-dien-1-yl)-L-alanine was formed. In tyrosyl-glycine and Leu-enkephalin, which have N-terminal tyrosines, bicyclic indolic para-hydroperoxide derivatives were formed ((2S,3aR,7aR)-3a-hydroperoxy-6-oxo-2,3,3a,6,7,7a-hexahydro-1H-indole-2-carboxylic acid) by the conjugate addition of the free amine to the cyclohexadienone. It was also found that significant amounts of the para-OH derivative were generated from the hydroxyl radical, formed on exposure of tyrosine-containing peptides to Fenton conditions. The para-OOH and para-OH derivatives are much more reactive than other tyrosine oxidation products and may play important roles in physiology and disease.

  2. Accessing naïve human pluripotency

    PubMed Central

    De Los Angeles, Alejandro; Loh, Yuin-Han; Tesar, Paul J; Daley, George Q

    2014-01-01

    Pluripotency manifests during mammalian development through formation of the epiblast, founder tissue of the embryo proper. Rodent pluripotent stem cells can be considered as two distinct states: naïve and primed. Naïve pluripotent stem cell lines are distinguished from primed cells by self-renewal in response to LIF signaling and MEK/GSK3 inhibition (LIF/2i conditions) and two active X chromosomes in female cells. In rodent cells, the naïve pluripotent state may be accessed through at least three routes: explantation of the inner cell mass, somatic cell reprogramming by ectopic Oct4, Sox2, Klf4, and C-myc, and direct reversion of primed post-implantation-associated epiblast stem cells (EpiSCs). In contrast to their rodent counterparts, human embryonic stem cells and induced pluripotent stem cells more closely resemble rodent primed EpiSCs. A critical question is whether naïve human pluripotent stem cells with bona fide features of both a pluripotent state and naïve-specific features can be obtained. In this review, we outline current understanding of the differences between these pluripotent states in mice, new perspectives on the origins of naïve pluripotency in rodents, and recent attempts to apply the rodent paradigm to capture naïve pluripotency in human cells. Unraveling how to stably induce naïve pluripotency in human cells will influence the full realization of human pluripotent stem cell biology and medicine. PMID:22463982

  3. Petrographic Evidence of Microbial Mats in the Upper Cretaceous Fish-Bearing, Organic-Rich Limestone, Agua Nueva Formation, Central Mexico

    NASA Astrophysics Data System (ADS)

    Blanco, A.; Maurrasse, F. J.; Hernández-Ávila, J.; Ángeles-Trigueros, S. A.; García-Cabrera, M. E.

    2013-05-01

    We document petrographic evidence of microbial mats in the Upper Cretaceous Agua Nueva Formation in the area of Xilitla (San Luis Potosí, Central Mexico), located in the southern part of the Tampico-Misantla basin. The sequence consists predominantly of alternating decimeter-thick beds of fossiliferous dark laminated limestone (C-org > 1.0wt%), and light gray, bioturbated limestone (C-org < 1.0wt%), with occasional brown shale and green bentonite layers. Well-preserved fossil-fish assemblages occur in the laminated dark limestone beds, which include shark teeth (cf. Ptychodus), scales of teleosteans (Ichthyodectiformes), as well as skeletal remains of holosteans (Nursallia. sp), and teleosteans (cf. Rhynchodercetis, Tselfatia, and unidentified Enchodontids). Thin section and SEM analyses of the laminated, dark limestones, reveal a micritic matrix consisting of dark and light sub-parallel wavy laminae, continuous and discontinuous folded laminae with shreds of organic matter, filaments, oncoids, and interlocking structures. The structures are identical to those previously described for the Cenomanian-Turonian Indidura Fm at Parras de la Fuente (Coahuila state) demonstrated to be of microbial origin (Duque-Botero and Maurrasse, 2005; 2008). These structures are also analogous to microbial mats in present environments, and Devonian deposits (Kremer, 2006). In addition, the laminae at Xilitla include filamentous bacterial structures, as thin and segmented red elements. In some thin sections, filaments appear to be embedded within the crinkly laminae and shreds showing the same pattern of folding, suggestive of biomorphic elements that represent the main producers of the organic matter associated with the laminae. Thus, exceptional bacterial activity characterizes sedimentation during the accumulation of the Agua Nueva Formation. Oxygen-deficient conditions related to the microbial mats were an important element in the mass mortality and preservation of the fish

  4. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yahia, H. Ben; Essehli, R., E-mail: ressehli@qf.org.qa; Avdeev, M.

    The new compounds NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} crystallize with a stuffed α-CrPO{sub 4}-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structuresmore » of NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} a statistical disorder Ni{sup 2+}/Cr{sup 3+} was observed on both the 8g and 4a atomic positions, whereas in NaCoCr{sub 2}(PO{sub 4}){sub 3} the statistical disorder Co{sup 2+}/Cr{sup 3+} was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} delivered specific capacities of 352, 385, and 368 mA h g{sup −1}, respectively, which attests to the electrochemical activity of sodium in these compounds. - Highlights: • NaCoCr{sub 2}(PO{sub 4}){sub 3}, NaNiCr{sub 2}(PO{sub 4}){sub 3}, and Na{sub 2}Ni{sub 2}Cr(PO{sub 4}){sub 3} were synthesized by sol-gel method. • The crystal structures were determined by using neutron powder diffraction data. • The three compounds crystallize with a stuffed α-CrPO{sub 4}-type structure. • The three compounds were tested as anodes in sodium-ion batteries. • Relatively high specific capacities were obtained for these compounds.« less

  5. Transcriptional regulators of Na,K-ATPase subunits

    PubMed Central

    Li, Zhiqin; Langhans, Sigrid A.

    2015-01-01

    The Na,K-ATPase classically serves as an ion pump creating an electrochemical gradient across the plasma membrane that is essential for transepithelial transport, nutrient uptake and membrane potential. In addition, Na,K-ATPase also functions as a receptor, a signal transducer and a cell adhesion molecule. With such diverse roles, it is understandable that the Na,K-ATPase subunits, the catalytic α-subunit, the β-subunit and the FXYD proteins, are controlled extensively during development and to accommodate physiological needs. The spatial and temporal expression of Na,K-ATPase is partially regulated at the transcriptional level. Numerous transcription factors, hormones, growth factors, lipids, and extracellular stimuli modulate the transcription of the Na,K-ATPase subunits. Moreover, epigenetic mechanisms also contribute to the regulation of Na,K-ATPase expression. With the ever growing knowledge about diseases associated with the malfunction of Na,K-ATPase, this review aims at summarizing the best-characterized transcription regulators that modulate Na,K-ATPase subunit levels. As abnormal expression of Na,K-ATPase subunits has been observed in many carcinoma, we will also discuss transcription factors that are associated with epithelial-mesenchymal transition, a crucial step in the progression of many tumors to malignant disease. PMID:26579519

  6. Sepsis does not alter red blood cell glucose metabolism or Na+ concentration: A 2H-, 23Na-NMR study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hotchkiss, R.S.; Song, S.K.; Ling, C.S.

    The effects of sepsis on intracellular Na+ concentration ((Na+)i) and glucose metabolism were examined in rat red blood cells (RBCs) by using 23Na- and 2H-nuclear magnetic resonance (NMR) spectroscopy. Sepsis was induced in 15 halothane-anesthetized female Sprague-Dawley rats by using the cecal ligation and perforation technique; 14 control rats underwent cecal manipulation without ligation. The animals were fasted for 36 h, but allowed free access to water. At 36 h postsurgery, RBCs were examined by 23Na-NMR by using dysprosium tripolyphosphate as a chemical shift reagent. Human RBCs from 17 critically ill nonseptic patients and from 7 patients who were diagnosedmore » as septic were also examined for (Na+)i. Five rat RBC specimens had (Na+)i determined by both 23Na-NMR and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). For glucose metabolism studies, RBCs from septic and control rats were suspended in modified Krebs-Henseleit buffer containing (6,6-2H2)glucose and examined by 2H-NMR. No significant differences in (Na+)i or glucose utilization were found in RBCs from control or septic rats. There were no differences in (Na+)i in the two groups of patients. The (Na+)i determined by NMR spectroscopy agreed closely with measurements using ICP-AES and establish that 100% of the (Na+)i of the RBC is visible by NMR. Glucose measurements determined by 2H-NMR correlated closely (correlation coefficient = 0.93) with enzymatic analysis. These studies showed no evidence that sepsis disturbed RBC membrane function or metabolism.« less

  7. [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.

  8. High pressure structural stability of the Na-Te system

    NASA Astrophysics Data System (ADS)

    Wang, Youchun; Tian, Fubo; Li, Da; Duan, Defang; Xie, Hui; Liu, Bingbing; Zhou, Qiang; Cui, Tian

    2018-03-01

    The ab initio evolutionary algorithm is used to search for all thermodynamically stable Na-Te compounds at extreme pressure. In our calculations, several new structures are discovered at high pressure, namely, Imma Na2Te, Pmmm NaTe, Imma Na8Te2 and P4/mmm NaTe3. Like the known structures of Na2Te (Fm-3m, Pnma and P63/mmc), the Pmmm NaTe, Imma Na8Te2 and P4/mmm NaTe3 structures also show semiconductor properties with band-gap decreases when pressure increased. However, we find that the band-gap of Imma Na2Te structure increases with pressure. We presume that the result may be caused by the increasing of splitting between Te p states and Na s, Na p and Te d states. Furthermore, we think that the strong hybridization between Na p state and Te d state result in the band gap increasing with pressure.

  9. FTIR spectra of the solid solutions (Na0.88K0.12)VO3, (Na0.5K0.5)VO3, and Na(V0.66P0.34)O3

    NASA Astrophysics Data System (ADS)

    de Waal, D.; Heyns, A. M.

    1992-03-01

    It is known that three different solid solutions, (Na0.88K0.12)VO3, (Na0.5K0.5)VO3 and Na(V0.66P0.34)O3, form in the (Na,K)(V,P)O3 system. These compounds all have monoclinic crystal structures similar to the pure alkali metal metavanadates containing small cations, e.g. Li+ and Na+ (Space group C2/c). Metavanadates with large cations like K+, Rb+, C+s and NH+4 form orthorhombic crystals, space group Pbcm. All those are structurally related to the silicate pyroxenes. Na(V0.66P0.34)O3 and (Na0.88K0.12)VO3 have the same modified diopside structure as (alpha) - NaVO3 while (Na0.5K0.5)VO3 adopts the true diopside structure. The infrared spectra of the three solid solutions are reported here in comparison with those of (alpha) -NaVO3 and KVO3. The results are also correlated with those obtained in two independent high pressure Raman studies of NH4VO3 and RbVO3 as the introduction of a larger cation like K+ should increase the pressure in the structure.

  10. A computational study of Na behavior on graphene

    NASA Astrophysics Data System (ADS)

    Malyi, Oleksandr I.; Sopiha, Kostiantyn; Kulish, Vadym V.; Tan, Teck L.; Manzhos, Sergei; Persson, Clas

    2015-04-01

    We present the first ab initio and molecular dynamics study of Na adsorption and diffusion on ideal graphene that considers Na-Na interaction and dispersion forces. From density functional theory (DFT) calculations using the generalized gradient approximation (GGA), the binding energy (vs. the vacuum reference state) of -0.75 eV is higher than the cohesive energy of Na metal (ENa metal cohesive energy (EcohDFT - D = - 1.21 eV) when dispersion correction is included (DFT-D), with Eb = -1.14 eV. Both DFT and DFT-D predict that the increase of Na concentration on graphene results in formation of Na complexes. This is evidenced by smaller Bader charge on Na atoms of Na dimer, 0.55e (0.48e for DFT) compared to 0.86e (for both DFT and DFT-D) for the single atom adsorption as well as by the formation of a Nasbnd Na bond identified by analysis of the electron density. These results suggest that ideal graphene is not a promising anode material for Na-ion batteries. Analysis of diffusion pathways for a Na dimer shows that the dimer remains stable during the diffusion, and computed migration barriers are significantly lower for the dimer than that for the single atom diffusion. This indicates that Na-Na interaction should be taken into account during the analysis of Na transport on graphene. Finally, we show that the typical defects (vacancy and divacancy) induce significant strengthening of the Nasbnd C interaction. In particular, the largest change to the interaction is computed for vacancy-defected graphene, where the found lowest binding energy (vs. the metal reference state) is about 1.15 eV (1.21 eV for DFT) lower than that for ideal graphene.

  11. Thyroid thermogenesis. Relationships between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in rat skeletal muscle.

    PubMed Central

    Asano, Y; Liberman, U A; Edelman, I S

    1976-01-01

    The effect of thyroid status on QO2, QO2 (t) and NaK-ATPase activity was examined in rat skeletal muscle. QO2(t) (i.e. Na+-transport-dependent respiration) was estimated with ouabain or Na+-free media supplemented with K+. In contrast to the effects of ouabain on ion composition, intracellular K+ was maintained at about 125 meq/liter, and intracellular Na+ was almost nil in the Na+-free media. The estimates of QO2(t) were independent of the considerable differences in tissue ion concentrations. The increase in QO2(t) account for 47% of the increase in QO2 in the transition from the hypothyroid to the euthyroid state and 84% of the increase in the transition from the euthyroid to the hyperthyroid state. Surgical thyroidectomy lowered NaK-ATPase activity of the microsomal fraction (expressed per milligram protein) 32%; injections of triodothyronine (T3) increased this activity 75% in initially hypothyroid rats and 26% in initially euthyroid rats. Thyroidectomy was attended by significant falls in serum Ca and Pi concentrations. Administration of T3 resulted in further declines in serum Ca and marked increases in serum Ps concentrations. Similar effects were seen in 131I-treated rats, but the magnitude of the declines in serum Ca were less. The effects of T3 on QO2, QO2(t), and NaK-ATPase activity of skeletal muscle were indistinguishable in the 131I-ablated and surgically thyroidectomized rats. In thyroidectomized or euthyroid rats given repeated doses of T3, QO2(t) and NaA-ATPase activity increased proportionately. In thyroidectomized rats injected with single doses of T3, either 10, 50, or 250 mug/100 g body wt, QO2(t) increased linearly with NaK-ATPase activity. The kinetics of the NaK-ATPase activity was assessed with an ATP-generating system. T3 elicited a significant increase in Vmax with no change in Km for ATP. PMID:130385

  12. Laser-induced chemiluminescence of NaMg

    NASA Astrophysics Data System (ADS)

    Benard, D. J.; Michels, H. H.

    1982-03-01

    An unstructured continuum emission around 670 nm was observed when Mg was added to an optically pumped heat pipe containing Na and K vapor, in good agreement with ab initio calculations of the NaMg potential energy curves. The corresponding excitation spectrum showed that the incident radiation was observed by NaK molecules (X → C transitions).

  13. Use and abuse of the urban groundwater resource: Implications for a new management strategy

    NASA Astrophysics Data System (ADS)

    Drangert, J.-O.; Cronin, A. A.

    'OMS et UNICEF), établissant que la plupart des eaux résiduaires des zones urbaines reste non traitée (65% en Asie, 86% en Amérique latine et 100% en Afrique). La tâche à réaliser pour l'homme est de protéger les ressources en eau souterraine en sorte qu'elle reste disponible pour les habitants des villes dans le futur. Dans les prochaines 50 années, il faut s'attendre à ce que la population urbaine s'accroisse de 3 à 6 milliards de personnes selon les estimations des Nations Unies; aussi il est impératif de ne pas continuer à polluer les eaux souterraines sous les nouvelles zones urbaines en cours de construction. Dans cet article, nous analyserons la qualité des eaux souterraines et leur protection à la lumière des récents changements de politique de l'eau, c'est-à-dire de la gestion de l'alimentation en eau jusqu'à une gestion de la demande et en abordant éventuellement la période de gestion du recyclage. La urbanización lleva a una demanda elevada y concentrada de agua de calidad adecuada, acompañada por el vertido de volúmenes análogamente mayores de aguas residuales. Los alimentos se importan a ciudades donde los microorganismos y nutrientes de los excrementos humanos son descargados a ríos, lagos y, también, aguas subterráneas. Más aún, gran número de los bienes de consumo son eliminados vía las tuberías de las cloacas. Las deudas medioambientales, es decir, el empobrecimiento de las condiciones medioambientales, que requerirán de aportaciones humanas y económicas para rehabilitarlas, son comunes a todas las ciudades, sobretodo en el Hemisferio Sur, donde, según la Valoración Global de Suministro de Agua y Saneamiento (OMS y UNICEF), la mayor parte de las aguas residuales urbanas no son tratadas (65% en Asia, 86% en Latinoamérica, 100% en África). La tarea pendiente consiste en proteger los recursos de aguas subterráneas para que estén disponibles de forma rápida para los habitantes urbanos también el futuro. En los pr

  14. Plan for a groundwater monitoring network in Taiwan

    NASA Astrophysics Data System (ADS)

    Hsu, Shiang-Kueen

    suivi des eaux souterraines à Taïwan". D'après ce programme, les données de base concernant les eaux souterraines, comprenant les mesures de niveau et les données de qualité, ont été acquises ; une base de données sûre est en cours d'élaboration, dans le but de gérer l'ensemble des ressources en eau. Cet article présente les buts, les stades de développement et une vue d'ensemble de ce plan. Le plan impose la mise en place de 517 stations de mesures hydrogéologiques et de 990 piézomètres en 17 ans. Selon ce programme, les variations du niveau des nappes doivent être suivies en continu, tandis que des échantillons pour la qualité de l'eau seront prélevés pour analyses uniquement au cours de la phase de foration, puis au moment de la mise en service des piézomètres. En 1996, le Département des Ressources en Eau et la Commission de Planification des Ressources en Eau ont été réunis pour former l'actuel Bureau des Ressources en Eau. Resumen En Taiwan, el rápido crecimiento económico, el aumento en el nivel de vida y los cambios sociales en los últimos años han resultado en un aumento en la demanda de agua. Por su estabilidad en términos de cantidad y calidad, las aguas subterráneas han sido durante años la fuente de agua para usos domésticos, agrícolas e industriales. En los últimos años, sin embargo, el establecimiento de un programa de gestión conjunta de aguas superficiales y subterráneas se ha visto comprometido por la falta de datos correspondientes a estas últimas. En 1992, el Departamento de Recursos de Agua (DWR) inició un programa titulado "Plan de Red de Control de Aguas Subterráneas en Taiwan". Bajo este programa, se están recogiendo datos básicos, incluyendo niveles piezométricos y datos de calidad, y se está construyendo una base de datos con el propósito de gestionar los recursos de agua totales. Este artículo presenta el marco, los objetivos y el estado de implantación del plan, que pretende la construcci

  15. Advancement of technology towards developing Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Jamesh, Mohammed Ibrahim; Prakash, A. S.

    2018-02-01

    The Na-ion-batteries are considered much attention for the next-generation power-sources due to the high abundance of Na resources that lower the cost and become the alternative for the state of the art Li-ion batteries in future. In this review, the recently reported potential cathode and anode candidates for Na-ion-batteries are identified in-light-of-their high-performance for the development of Na-ion-full-cells. Further, the recent-progress on the Na-ion full-cells including the strategies used to improve the high cycling-performance (stable even up-to 50000 cycles), operating voltage (even ≥ 3.7 V), capacity (>350 mAhg-1 even at 1000 mAg-1 (based-on-mass-of-the-anode)), and energy density (even up-to 400 Whkg-1) are reviewed. In addition, Na-ion-batteries with the electrodes containing reduced graphene oxide, and the recent developments on symmetric Na-ion-batteries are discussed. Further, this paper identifies the promising Na-ion-batteries including the strategies used to assemble full-cell using hard-carbon-anodes, Na3V2(PO4)3 cathodes, and other-electrode-materials. Then, comparison between aqueous and non-aqueous Na-ion-batteries in terms of voltage and energy density has been given. Later, various types of electrolytes used for Na-ion-batteries including aqueous, non-aqueous, ionic-liquids and solid-state electrolytes are discussed. Finally, commercial and technological-developments on Na-ion-batteries are provided. The scientific and engineering knowledge gained on Na-ion-batteries afford conceivable development for practical application in near future.

  16. Negative electrodes for Na-ion batteries.

    PubMed

    Dahbi, Mouad; Yabuuchi, Naoaki; Kubota, Kei; Tokiwa, Kazuyasu; Komaba, Shinichi

    2014-08-07

    Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on. These electrode materials have different reaction mechanisms for electrochemical sodiation/desodiation processes. Moreover, not only sodiation-active materials but also binders, current collectors, electrolytes and electrode/electrolyte interphase and its stabilization are essential for long cycle life Na-ion batteries. This paper also addresses the prospect of Na-ion batteries as low-cost and long-life batteries with relatively high-energy density as their potential competitive edge over the commercialized Li-ion batteries.

  17. Implementação de um algoritmo para a limpeza de mapas da RCFM

    NASA Astrophysics Data System (ADS)

    Souza, C. L.; Wuensche, C. A.

    2003-08-01

    A Radiação Cósmica de Fundo em Microondas (RCFM), descoberta por Penzias e Wilson em 1965, é uma das ferramentas mais poderosas para o estudo da cosmologia. Com a descoberta de flutuações de temperatura na RCFM, da ordem de uma parte em 105, pelo COBE (1992), uma nova era teve início. Nos últimos onze anos, diversos instrumentos fizeram novas medidas de alta precisão, refinando os resultados apresentados pelo COBE, culminando com os resultados recentes do satélite WMAP. A análise de dados da RCFM, especialmente no caso de experimentos com pequena cobertura do céu, apresenta uma série de dificuldades devido a emissões de contaminantes externos, tais como a emissão da Galáxia e de fontes pontuais, e de ruídos intrínsecos tanto ao sistema de detecção quanto à estratégia de observação do céu. Uma das soluções típicas para a filtragem de dados brutos de um experimento para medir flutuações de temperatura é aplicar um gabarito (template) e um filtro passa alta ao produzir mapas simplificados (sem considerar matrizes de correlação ou covariância). No caso de experimentos que utilizam detectores HEMT, essa combinação de filtros remove, satisfatoriamente, ruídos do tipo 1/f gerados pela instabilidade no ganho do detector acoplado ao movimento do instrumento, definido pela estratégia de observação. Entretanto, o sinal resultante medido, tanto em simulações quanto em séries temporais reais, sugere que parte do sinal cosmológico pode estar sendo removido junto com o ruído dos detectores. Este trabalho descreve as etapas para a produção de um mapa típico (simulado) e os testes preliminares de um algoritmo para remover ruídos do tipo 1/f introduzidos pela estratégia de observação sem prejudicar a qualidade do sinal cosmológico presente no mapa.

  18. Tribosystems based on multilayered micro/nanocrystalline CVD diamond coatings =

    NASA Astrophysics Data System (ADS)

    Shabani, Mohammadmehdi

    substrato, ao contrario do que acontece com os revestimentos monocamada. Os aneis de empanque testados com biodiesel apresentaram coeficientes de desgaste (4,1x10-10 mm3N-1m-1) duas ordens de grandeza menores do que em ensaios esfera-sobre-plano em movimento reciproco (k = 5,0x10-8 mm3N-1m-1), mas nao foi possivel obter vedacao completa devido a sobreaquecimento do fluido. Esta condicao foi obtida com agua sob pressao, para condicoes P.V na gama 0,72-5,3 MPa.ms-1. Um coeficiente de atrito em estado estacionario de 0,04 e um valor de coeficiente de desgaste de 6,0x10-10 mm3N-1m-1, caracteristico de um regime desgaste ultra-suave, revelam o alto desempenho deste tribossistema.

  19. 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. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  20. Elastic Coulomb breakup of 34Na

    NASA Astrophysics Data System (ADS)

    Singh, G.; Shubhchintak, Chatterjee, R.

    2016-08-01

    Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

  1. Resurgent current of voltage-gated Na+ channels

    PubMed Central

    Lewis, Amanda H; Raman, Indira M

    2014-01-01

    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 NaVβ4 (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

  2. 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Integrated Control of Na Transport along the Nephron

    PubMed Central

    Schnermann, Jürgen

    2015-01-01

    The kidney filters vast quantities of Na at the glomerulus but excretes a very small fraction of this Na in the final urine. Although almost every nephron segment participates in the reabsorption of Na in the normal kidney, the proximal segments (from the glomerulus to the macula densa) and the distal segments (past the macula densa) play different roles. The proximal tubule and the thick ascending limb of the loop of Henle interact with the filtration apparatus to deliver Na to the distal nephron at a rather constant rate. This involves regulation of both filtration and reabsorption through the processes of glomerulotubular balance and tubuloglomerular feedback. The more distal segments, including the distal convoluted tubule (DCT), connecting tubule, and collecting duct, regulate Na reabsorption to match the excretion with dietary intake. The relative amounts of Na reabsorbed in the DCT, which mainly reabsorbs NaCl, and by more downstream segments that exchange Na for K are variable, allowing the simultaneous regulation of both Na and K excretion. PMID:25098598

  4. Electrical resistivity of liquid Na-alkali alloys

    NASA Astrophysics Data System (ADS)

    Malan, Rajesh C.; Vora, Aditya M.

    2018-05-01

    The electrical resistivity (ρ) has been investigated for the liquid Na-alkali alloys. An effort is made to extend the applicability of the potential suggested by Fiolhais and co-workers to the liquid range for alkali group. The universal parameters of the potential are used for the entire calculation. Eight different screening functions proposed by Hartree (H), Hubbard and Sham (HS), Vashishtha and Shingwi (VS), Taylor (T), Ichimaru and Utsumi (IU), Farid et al. (F), Sarkar et al. (S) and Nagy (N) are used to study the electrical resistivity (ρ) of liquid Na-alkali alloys with well-known Faber-Ziman theory along with Percus-Yevic hard sphere (PYHS) reference system. The results of electrical resistivity (ρ) are found in qualitative agreement with experimental data for the Na-K and Na-Rb alloys than those for Na-Li and Na-Cs alloys.

  5. The Na+ transport in gram-positive bacteria defect in the Mrp antiporter complex measured with 23Na nuclear magnetic resonance.

    PubMed

    Górecki, Kamil; Hägerhäll, Cecilia; Drakenberg, Torbjörn

    2014-01-15

    (23)Na nuclear magnetic resonance (NMR) has previously been used to monitor Na(+) translocation across membranes in gram-negative bacteria and in various other organelles and liposomes using a membrane-impermeable shift reagent to resolve the signals resulting from internal and external Na(+). In this work, the (23)Na NMR method was adapted for measurements of internal Na(+) concentration in the gram-positive bacterium Bacillus subtilis, with the aim of assessing the Na(+) translocation activity of the Mrp (multiple resistance and pH) antiporter complex, a member of the cation proton antiporter-3 (CPA-3) family. The sodium-sensitive growth phenotype observed in a B. subtilis strain with the gene encoding MrpA deleted could indeed be correlated to the inability of this strain to maintain a lower internal Na(+) concentration than an external one. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aboussatar, Mohamed; Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax; Mbarek, Aïcha

    Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1),more » c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F

  7. Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

    NASA Astrophysics Data System (ADS)

    Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

    2017-04-01

    Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

  8. 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.

  9. Puerto Rico, humedales [Puerto Rico, wetlands

    USGS Publications Warehouse

    Adams, D. Briane; Hefner, John M.; Dopazo, Teresa

    1999-01-01

    La isla de Puerto Rico, localizada al noreste del Mar Caribe y sus islas principales, Vieques, Culebra e Isla de Mona, poseen humedales en abundancia . El clima subtropical, la lluvia abundante y las complejas formas topográficas y geológicas de estas islas dan origen a los humedales, que varían desde los raros e inusuales bosques cubiertos por nubes en las tierras altas, hasta los extensos manglares, yerbas marinas y arrecifes de coral a lo largo de las costas Norte y Sur. Sin embargo, los humedales en Puerto Rico han disminuido en los últimos siglos como resultado del aumento en el desarrollo agrícola, poblacional y turístico. Algunos tipos de humedales como los bosques de palo de pollo (Pterocarpus officinalis) se han reducido a sólo unos pocos remanentes (figura 1).Biológicamente hablando, los humedales de las islas están entre las áreas más productivas. Los humedales asociados con el bosque pluvial en las tierras altas del interior de Puerto Rico contienen varias plantas raras y especies de animales que no se encuentran en otras partes de la Isla. El agua de escorrentía proveniente de los humedales en las partes altas de la Isla proveen una fuente de agua que utilizan varias ciudades para abasto público. Los humedales costeros como los mangles, los colchones de yerbas marinas y los arrecifes de coral proveen áreas para la reproducción y crianza de varios peces, crustáceos y otras especies en la cadena alimenticia (López y otros, 1988). De esta manera, los humedales costeros contribuyen a la productividad biológica de las aguas llanas del mar alrededor de las islas . Los humedales también estabilizan las costas atrapando y reteniendo sedimentos no consolidados y amortiguan la acción de las olas y de las tormentas que tienen el potencial de causar daños en la zona.El valor de los humedales de Puerto Rico para la vida silvestre está muy bien documentado . Por ejemplo, las salinas de Cabo Rojo, en la costa suroeste, proveen áreas para el

  10. Effects of NaBF4 + NaF on the Tensile and Impact Properties of Al-Si-Mg-Fe Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Zongning; Wang, Tongmin; Zhao, Yufei; Zheng, Yuanping; Kang, Huijun

    2015-05-01

    NaBF4 + NaF were found to play three roles, i.e., Fe-eliminator, grain refiner, and eutectic modifier, in treating A356 alloy with a high Fe content. The joint effects led to significant improvement in both tensile and impact properties of thus treated alloy. The multiple reactions between the NaBF4 + NaF and Al-Si-Mg-Fe system are suggested to form Fe2B, AlB2, and Na in the melt, as per thermodynamic analysis. The three are responsible for Fe removal, grain refinement, and eutectic modification, respectively. When NaBF4 and NaF are mixed in weight ratio of 1:1, an optimum addition rate is in the range between 1.0 and 2.0 wt pct for treating AlSi7Mg0.3Fe0.65 alloy, based on the results of tensile and impact tests. Excessive addition of the salt may deteriorate the mechanical properties of the alloy, basically owing to overmodification of Si and contamination of salt inclusions.

  11. Efeitos do binarismo não resolvido na determinação da função de massa de aglomerados

    NASA Astrophysics Data System (ADS)

    Kerber, L. O.; Santiago, B. X.

    2003-08-01

    Através de simulações numéricas buscamos quantificar os efeitos que o binarismo não resolvido causa na determinação da função de massa (MF) de aglomerados estelares. Geramos diagramas cor-magnitude (CMDs) artificiais simulando uma população única, caracterizada por estrelas de mesma idade e composição quí mica, com uma fração de binárias não resolvidas e distribuição em massa das estrelas dada por uma MF do tipo lei de potência. A presença de pares de estrelas não resolvidos faz com que a MF obtida da função de luminosidade (LF) tenha a têndencia de ser mais plana do que a MF que gerou o CMD artificial. Propomos um tratamento de correção para tal efeito. Outro efeito relacionado diz respeito ao alargamento do CMD, que apresenta-se como um indicador do número total de estrelas no domí nio de baixas massas (m < 0.6M¤). Todos os resultados acima possuem uma forte dependência com os erros fotométricos e estão baseados na hipótese de que ambas estrelas do par não resolvido são sorteadas de uma mesma MF de forma independente. O objetivo final é aplicarmos o tratamento aqui desenvolvido para implementarmos a análise da nossa amostra de aglomerados ricos da Grande Nuvem de Magalhães.

  12. Modulation of voltage-gated Na+ and K+ channels by pumiliotoxin 251D: a "joint venture" alkaloid from arthropods and amphibians.

    PubMed

    Vandendriessche, Thomas; Abdel-Mottaleb, Yousra; Maertens, Chantal; Cuypers, Eva; Sudau, Alexander; Nubbemeyer, Udo; Mebs, Dietrich; Tytgat, Jan

    2008-03-01

    Certain amphibians provide themselves with a chemical defense by accumulating lipophilic alkaloids into skin glands from dietary arthropods. Examples of such alkaloids are pumiliotoxins (PTXs). In general, PTXs are known as positive modulators of voltage-gated sodium channels (VGSCs). Unlike other PTXs, PTX 251D does not share this characteristic. However, mice and insect studies showed that PTX 251D is highly toxic and to date the basis of its toxicity remains unknown. In this work, we searched for the possible target of PTX 251D. The toxin was therefore made synthetically and tested on four VGSCs (mammalian rNa(v)1.2/beta(1), rNa(v)1.4/beta(1), hNa(v)1.5/beta(1) and insect Para/tipE) and five voltage-gated potassium channels (VGPCs) (mammalian rK(v)1.1-1.2, hK(v)1.3, hK(v)11.1 (hERG) and insect Shaker IR) expressed heterologously in Xenopus laevis oocytes, using the two-electrode voltage clamp technique. PTX 251D not only inhibited the Na(+) influx through the mammalian VGSCs but also affected the steady-state activation and inactivation. Interestingly, in the insect ortholog, the inactivation process was dramatically affected. Additionally, PTX 251D inhibited the K(+) efflux through all five tested VGPCs and slowed down the deactivation kinetics of the mammalian VGPCs. hK(v)1.3 was the most sensitive channel, with an IC(50) value 10.8+/-0.5 microM. To the best of our knowledge this is the first report of a PTX affecting VGPCs.

  13. 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.

  14. Quantitative (23) Na MRI of human knee cartilage using dual-tuned (1) H/(23) Na transceiver array radiofrequency coil at 7 tesla.

    PubMed

    Moon, Chan Hong; Kim, Jung-Hwan; Zhao, Tiejun; Bae, Kyongtae Ty

    2013-11-01

    To develop quantitative dual-tuned (DT) (1) H/(23) Na MRI of human knee cartilage in vivo at 7 Tesla (T). A sensitive (23) Na transceiver array RF coil was developed at 7T. B1 fields generated by the transceiver array coil were characterized and corrected in the (23) Na images. Point spread function (PSF) of the (23) Na images was measured, and the signal decrease due to partial-volume-effect was compensated in [(23) Na] quantification of knee cartilage. SNR and [(23) Na] in anterior femoral cartilage were measured from seven healthy subjects. SNR of (23) Na image with the transceiver array coil was higher than that of birdcage coil. SNR in the cartilage at 2-mm isotropic resolution was 26.80 ± 3.69 (n = 7). B1 transmission and reception fields produced by the DT coil at 7T were similar to each other. Effective full-width-half-maximum of (23) Na image was ∼5 mm at 2-mm resolution. Mean [(23) Na] was 288.13 ± 29.50 mM (n = 7) in the anterior femoral cartilage of normal subjects. We developed a new high-sensitivity (23) Na RF coil for knee MRI at 7T. Our (1) H/(23) Na MRI allowed quantitative measurement of [(23) Na] in knee cartilage by measuring PSF and cartilage thickness from (23) Na and (1) H image, respectively. Copyright © 2013 Wiley Periodicals, Inc.

  15. Quantification of Sodium (Na) in Bone with in Vivo Neutron Activation Analysis (IVNAA) and Its Implications on Na Retention Studies

    NASA Astrophysics Data System (ADS)

    Coyne, Mychaela

    The locations of Na storage and its exchange mechanisms in different tissues in the body are not well known. This information is important for understanding the impact of Na intake, absorption, and retention on human health, especially on the risk of developing chronic diseases like hypertension. In order to non-invasively quantify Na in bone, a compact deuterium-deuterium (DD) neutron generator-based IVNAA system was developed for use in Na nutrition studies. This thesis will first discuss the optimization of the system using MCNP to maximize the thermal neutron flux inside the irradiation cave while limiting radiation exposure to the hand and the whole body. With optimized assembly in place, an animal study was conducted to investigate the storage and exchange of Na in the body. The right posterior legs of two live pigs, one on a low Na diet and one on a high Na diet, were irradiated inside the customized assembly and then measured with a 100% high efficiency high purity germanium detector (HPGe). The results show that the difference in concentration between the pigs on high vs low Na diets was distinguishable with the system. Analysis also shows rapid exchange of Na in the leg during the first 2 hour measurements (with an exchange decay time of 1.3 hours) while the exchange was minimal at the second and third 2 hour measurements, taken 7 and 21 hours post irradiation. With these results, we conclude there is a non or low exchangeable compartment (likely to be bone) for Na storage and that the DD neutron generator-based IVNAA is a useful method in Na nutrition studies.

  16. Characterisation of the sedimentary processes responsible for the filling and excavation of two intra mountainous basins (Agua Amarga and Collon Cura) in the Andes of Neuquén (Argentina) during the Neogene

    NASA Astrophysics Data System (ADS)

    Bonnel, C.; Huyghe, D.; Nivière, B.; Messager, G.; Dhont, D.; Fasentieux, B.; Hervouët, Y.; Xavier, J.-P.

    2012-04-01

    Intramontane basins constitute potential good recorders of orogenic systems deformation history through the documentation of their remnant sedimentary filling and observation of syntectonic growth strata. In this work, we focus on the Neuquén basin, located on the eastern flank of the Andes between 32°S and 41°S latitude. It has been structured since the late Triassic, first as back arc basin and as compressive foreland basin since the upper Cretaceous. Most of the sedimentary filling is composed of Mesozoic sediments, which have been importantly studied because of their hydrocarbon potential. On the contrary, Cenozoic tectonic and sedimentologic evolutions remain poorly documented in regard to the Mesozoic. The structural inheritance is very important and strongly influences the deformation and shortening rates from the North to the South of the basin. Thus, the northern part exhibits a classical configuration from the western high Andes, to younger fold and thrust belts and piggy-back basins to the East. On the contrary, no fold and thrust belt exist in the southern part of the basin and the deformation is restricted to the internal domain. Nevertheless, contemporaneous intramontane basins (the Agua Amarga to the North and the Collon Cura basin to the South) existed in these two parts of the basin and seem to have followed a similar evolution despite of a different structural context. To the North, the partial closing of the Agua Amarga basin by the growth of the Chuihuidos anticlines during the Miocene is characterised by the deposition of a fining upward continental sequence of ~250 m thick, from lacustrine environment at the base to alluvial and fluviatile environments in the upper part of the section. In the Collon Cura, the sedimentary filling, due to the rising of the Piedra del Aguila basement massif, reach at maximum 500 m and consist in fluvial tuffaceous material in the lower part to paleosoils and coarse conglomeratic fluvial deposits in the upper

  17. Na(+) transport, and the E(1)P-E(2)P conformational transition of the Na(+)/K(+)-ATPase.

    PubMed Central

    Babes, A; Fendler, K

    2000-01-01

    We have used admittance analysis together with the black lipid membrane technique to analyze electrogenic reactions within the Na(+) branch of the reaction cycle of the Na(+)/K(+)-ATPase. ATP release by flash photolysis of caged ATP induced changes in the admittance of the compound membrane system that are associated with partial reactions of the Na(+)/K(+)-ATPase. Frequency spectra and the Na(+) dependence of the capacitive signal are consistent with an electrogenic or electroneutral E(1)P <--> E(2)P conformational transition which is rate limiting for a faster electrogenic Na(+) dissociation reaction. We determine the relaxation rate of the rate-limiting reaction and the equilibrium constants for both reactions at pH 6.2-8.5. The relaxation rate has a maximum value at pH 7.4 (approximately 320 s(-1)), which drops to acidic (approximately 190 s(-1)) and basic (approximately 110 s(-1)) pH. The E(1)P <--> E(2)P equilibrium is approximately at a midpoint position at pH 6.2 (equilibrium constant approximately 0.8) but moves more to the E(1)P side at basic pH 8.5 (equilibrium constant approximately 0.4). The Na(+) affinity at the extracellular binding site decreases from approximately 900 mM at pH 6.2 to approximately 200 mM at pH 8.5. The results suggest that during Na(+) transport the free energy supplied by the hydrolysis of ATP is mainly used for the generation of a low-affinity extracellular Na(+) discharge site. Ionic strength and lyotropic anions both decrease the relaxation rate. However, while ionic strength does not change the position of the conformational equilibrium E(1)P <--> E(2)P, lyotropic anions shift it to E(1)P. PMID:11053130

  18. Magnetic upconverting fluorescent NaGdF4:Ln3+ and iron-oxide@NaGdF4:Ln3+ nanoparticles

    NASA Astrophysics Data System (ADS)

    Shrivastava, Navadeep; Rocha, Uéslen; Muraca, Diego; Jacinto, Carlos; Moreno, Sergio; Vargas, J. M.; Sharma, S. K.

    2018-05-01

    Microwave assisted solvothermal method has been employed to synthesize multifunctional upconverting β-NaGdF4:Ln3+ and magnetic-upconverting Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (Ln = Yb and Er) nanoparticles. The powder x-ray diffraction data confirms the hexagonal structure of NaGdF4:Ln3+ and high resolution transmission electron microscopy shows the formation of rod shaped NaGdF4:Ln3+ (˜ 20 nm) and ovoid shaped Fe3O4/γ-Fe2O3@NaGdF4:Ln3+ (˜ 15 nm) nanoparticles. The magnetic hysteresis at 300 K for β-NaGdF4:Ln3+ demonstrates paramagnetic features, whereas iron-oxide@β-NaGdF4:Ln3+ exhibits superparamagnetic behavior along with a linear component at large applied field due to paramagnetic NaGdF4 matrix. Both nanoparticle samples provide an excellent green emitting [(2H11/2, 4S3/2)→4I15/2 (˜ 540 nm)] upconversion luminescence emission under excitation at 980 nm. The energy migration between Yb and Er in NaGdF4 matrix has been explored from 300-800 nm. Intensity variation of blue, green and red lines and the observed luminescence quenching due to the presence of Fe3O4/γ-Fe2O3 in the composite has been proposed. These kinds of materials contain magnetic and luminescence characteristics into single nanoparticle open new possibility for bioimaging applications.

  19. Maintaining the NA atmosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Killen, R. M.; Morgan, T. H.

    1993-02-01

    The possible sources of the Na atmosphere of Mercury are calculatively studied. The likely structure, composition, and temperature of the planet's upper crust is examined along with the probable flux of Na from depth by grain boundary diffusion and by Knudsen flow. The creation of fresh regolith is considered along with mechanisms for supplying Na from the surface to the exosphere. The implications of the calculations for the probable abundances in the regolith are discussed.

  20. The plant vacuolar Na+/H+ antiport.

    PubMed

    Barkla, B J; Apse, M P; Manolson, M F; Blumwald, E

    1994-01-01

    Salt stress imposes severe limitations on plant growth, however, the extent of growth reduction depends upon the soil salinity level and the plant species. One of the mechanisms employed by salt tolerant plants is the effective vacuolar compartmentalization of sodium. The sequestration of sodium into the vacuole occurs by the operation of a Na+/H+ antiport located at the tonoplast. Evidence for a plant vacuolar Na+/H+ antiport has been demonstrated in tissues, intact vacuoles and isolated tonoplast vesicles. In sugar beet cell suspensions, the activity of the vacuolar Na+/H+ antiport increased with increasing NaCl concentrations in the growth medium. This increased activity was correlated with the increased synthesis of a 170 kDa tonoplast polypeptide. In vivo labelling of tonoplast proteins showed the enhanced synthesis of the 170 kDa polypeptide not only upon exposure of the cells to salt, but also when the cells were grown in the presence of amiloride. Exposure of the cells to amiloride also resulted in increased vacuolar Na+/H+ antiport activity. Polyclonal antibodies raised against the 170 kDa polypeptide almost completely inhibited the antiport activity, suggesting the association of this protein with the plant vacuolar Na+/H+ antiport. Antibodies against the Na+/H+ antiport-associated polypeptide were used to screen a Beta lambda ZAP expression library. A partial clone of 1.65 kb was sequenced and found to encode a polypeptide with a putative transmembrane domain and a large hydrophilic C terminus. This clone showed no homology to any previously cloned gene at either the nucleic acid or the amino acid level.

  1. Thermodynamic description of Tc(iv) solubility and carbonate complexation in alkaline NaHCO3-Na2CO3-NaCl systems.

    PubMed

    Baumann, A; Yalçıntaş, E; Gaona, X; Polly, R; Dardenne, K; Prüßmann, T; Rothe, J; Altmaier, M; Geckeis, H

    2018-03-28

    The solubility of 99 Tc(iv) was investigated in dilute to concentrated carbonate solutions (0.01 M ≤ C tot ≤ 1.0 M, with C tot = [HCO 3 - ] + [CO 3 2- ]) under systematic variation of ionic strength (I = 0.3-5.0 M NaHCO 3 -Na 2 CO 3 -NaCl-NaOH) and pH m (-log[H + ] = 8.5-14.5). Strongly reducing conditions (pe + pH m ≈ 2) were set with Sn(ii). Carbonate enhances the solubility of Tc(iv) in alkaline conditions by up to 3.5 log 10 -units compared to carbonate-free systems. Solvent extraction and XANES confirmed that Tc was kept as +IV during the timeframe of the experiments (≤ 650 days). Solid phase characterization performed by XAFS, XRD, SEM-EDS, chemical analysis and TG-DTA confirmed that TcO 2 ·0.6H 2 O(am) controls the solubility of Tc(iv) under the conditions investigated. Slope analysis of the solubility data in combination with solid/aqueous phase characterization and DFT calculations indicate the predominance of the species Tc(OH) 3 CO 3 - at pH m ≤ 11 and C tot ≥ 0.01 M, for which thermodynamic and activity models are derived. Solubility data obtained above pH m ≈ 11 indicates the formation of previously unreported Tc(iv)-carbonate species, possibly Tc(OH) 4 CO 3 2- , although the likely formation of additional complexes prevents deriving a thermodynamic model valid for this pH m -region. This work provides the most comprehensive thermodynamic dataset available for the system Tc 4+ -Na + -Cl - -OH - -HCO 3 - -CO 3 2- -H 2 O(l) valid under a range of conditions relevant for nuclear waste disposal.

  2. The Na+-Responsive ntp Operon Is Indispensable for Homeostatis of K+ and Na+ in Enterococcus hirae at Limited Proton Potential

    PubMed Central

    Kawano, Miyuki; Igarashi, Kazuei; Kakinuma, Yoshimi

    1998-01-01

    Enterococcus hirae ATCC 9790 grew well in Na+-deficient, low-K+ medium, but growth was inhibited by carbonylcyanide m-chlorophenylhydrazone (CCCP). Growth inhibition and decrease of cellular K+ levels in the presence of CCCP were relieved by the addition of Na+ and a high concentration of K+. In contrast, in the mutant defective in Na+-ATPase or the NtpJ component of the KtrII K+ uptake system, CCCP-induced growth inhibition was rescued by a high concentration of K+ but not of Na+. These transporters are thus indispensable for homeostatis of K+ and Na+ at low proton potential. PMID:9733699

  3. Growth and characterization of struvite-Na crystals

    NASA Astrophysics Data System (ADS)

    Chauhan, Chetan K.; Joshi, Mihirkumar J.

    2014-09-01

    Sodium magnesium phosphate heptahydrate [NaMgPO4·7H2O], also known as struvite-Na, is the sodium analog to struvite. Among phosphate containing bio-minerals, struvite has attracted considerable attention, because of its common occurrence in a wide variety of environments. Struvite and family crystals were found as urinary calculi in humans and animals. Struvite-Na crystals were grown by a single diffusion gel growth technique in a silica hydro gel medium. Struvite-Na crystals with different morphologies having transparent to translucent diaphaneity were grown with different growth parameters. The phenomenon of Liesegang rings was also observed with some particular growth parameters. The powder XRD study confirmed the structural similarity of the grown struvite-Na crystals with struvite and found that struvite-Na crystallized in the orthorhombic Pmn21 space group with unit cell parameters such as a= 6.893 Å, b=6.124 Å, c=11.150 Å, and α=β=γ=90°. FT-IR spectra of struvite-Na crystals revealed the presence of functional groups. The TGA, DTA and DSC were carried out simultaneously. The kinetic and thermodynamic parameters of dehydration/decomposition process were calculated. The variation of dielectric constant with frequency of applied field was studied in the range from 400 Hz to 100 kHz.

  4. Producing and quantifying enriched para-H2.

    PubMed

    Tom, Brian A; Bhasker, Siddhartha; Miyamoto, Yuki; Momose, Takamasa; McCall, Benjamin J

    2009-01-01

    The production of enriched para-H(2) is useful for many scientific applications, but the technology for producing and measuring para-H(2) is not yet widespread. In this note and in the accompanying auxiliary material, we describe the design, construction, and use of a versatile standalone converter that is capable of producing para-H(2) enrichments of up to > or = 99.99% at continuous flow rates of up to 0.4 SLM. We also discuss para-H(2) storage and back conversion rates, and improvements to three techniques (thermal conductance, NMR, and solid hydrogen impurity spectroscopy) used to quantify the para-H(2) enrichment.

  5. 23Na and 35/37Cl as NMR probes of growth and shape of sodium taurodeoxycholate micellar aggregates in the presence of NaCl.

    PubMed

    Asaro, Fioretta; Feruglio, Luigi; Galantini, Luciano; Nardelli, Alessia

    2013-02-15

    The growth of the aggregates of the dihydroxylated bile salt sodium taurodeoxycholate (NaTDC) upon NaCl addition and the involvement of the counterion were investigated by NMR spectroscopy of monoatomic ionic species. (23)Na T(1) values from 0.015, 0.100, and 0.200 mol kg(-1) NaTDC solutions in D(2)O, at variable NaCl content, proved to be sensitive to the transition from primary to secondary aggregates, which occurs in the former sample, and to intermicellar interaction. Some (79)Br NMR measurements were performed on a 0.100 mol kg(-1) NaTDC sample added by NaBr in place of NaCl for comparison purposes. The (23)Na, (35)Cl, and (37)Cl double quantum filtered (DQF) patterns, from the 0.100 mol kg(-1) NaTDC sample, and (23)Na ones also from the 0.200 mol kg(-1) NaTDC one, in the presence of 0.750 mol kg(-1) NaCl, are a clear manifestation of motional anisotropy. Moreover, the DQF spectra of (23)Na and (37)Cl, which possess close quadrupole moments, display a striking similarity. The DQF lineshapes were simulated exploiting the Scilab environment to obtain an estimate of the residual quadrupole splitting magnitude. These results support the description of NaTDC micelles as cylindrical aggregates, strongly interacting at high ionic strengths, and capable of association with added electrolytes. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na 3OBr and Na 4OI 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yonggang; Wen, Ting; Park, Changyong

    2016-01-14

    The structure stability under high pressure and thermal expansion behavior of Na 3OBr and Na 4OI 2, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temp. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na 3OBr and Na 4OI 2, resp. The cubic Na 3OBr structure and tetragonal Na 4OI 2 with intergrowth K 2NiF 4 structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na 4OI 2 exhibits nearly isotropic compressibility. Neg. thermal expansion wasmore » obsd. at low temp. range (20-80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined. and confirmed by first-principles calculations. among various possible polymorphisms qualitatively. The results provide in-depth understanding of the neg. thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.« less

  7. Dipolar effects on propagation of ultrashort laser pulse in one-dimensional para-nitroaniline (pNA) molecules

    NASA Astrophysics Data System (ADS)

    Zhao, Ke; Li, Hong-Yu; Liu, Ji-Cai; Wang, Chuan-Kui; Luo, Yi

    2005-12-01

    The dynamic behaviour of ultrashort (femtosecond) laser pulses in a molecular medium is studied by solving the full Maxwell-Bloch equations beyond the limits of the slowly varying envelope approximation and the rotating-wave approximation under the resonant and the non-resonant conditions. A one-dimensional asymmetric charge-transfer molecule, para-nitroaniline, is used as a model molecule whose electronic properties are calculated with the time-dependent hybrid density functional theory. Under the one-photon resonant condition, 4π pulse is separated into two sub-pulses. The weight of the second-harmonic component mainly contributed by the two-photon excitation becomes stronger with longer propagation time. Under the two-photon resonant condition, the separation of 4π pulse is not induced and many higher-order spectral components beyond the second-harmonic generation occur. Interestingly, when the pulse propagates for long enough, the carrier modification becomes so significant that a continuous spectrum is generated. The Fourier transform of the high-harmonic spectrum demonstrates that an even shorter laser pulse can be produced in both resonant and non-resonant propagations. The effects of permanent dipole moments on the pulse evolution are discussed.

  8. 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

  9. Contenedores: Aspectos tecnicos, biologicos y economicos

    Treesearch

    Tara Luna; Thomas D. Landis; R. Kasten Dumroese

    2012-01-01

    La elección del contenedor es una de las consideraciones más importantes al establecer un nuevo vivero o empezar a producir una especie nueva. El tipo y tamaño de contenedor no sólo determina la cantidad de agua y nutrientes minerales que están disponibles para el crecimiento de una planta, sino que también afecta otros aspectos operativos del vivero, como el tamaño de...

  10. A distância e o conteúdo estelar da região HII gigante G333.1-0.4 - vínculos para a taxa de formação estelar da galáxia

    NASA Astrophysics Data System (ADS)

    Figuerêdo, E.; Damineli, A.; Blum, R.; Conti, P.

    2003-08-01

    Neste trabalho apresentamos imagens de alta resolução angular da região HII gigante G333.1-0.4 obtidas através dos filtros J, H e K no telescópio de 4-m do CTIO. Este trabalho faz parte de um estudo de regiões HII gigantes no infravermelho próximo que tem por objetivo estudar a natureza da formação de estrelas massivas e traçar a estrutura espiral de nossa galáxia. Nossa determinação da distância é baseada no método da paralaxe espectroscópica de estrelas OB localizadas na seqüência principal de idade zero (ZAMS) do Diagrama HR. No caso de G333.1-0.4, a magnitude aparente das estrelas localizadas na ZAMS indica que a distância não pode ser maior do que o limite inferior determinado por técnica rádio (2,8 kpc). Resultados semelhantes foram encontrados para regiões estudadas anteriormente, reforçando a idéia de que a taxa de formação estelar na Via Láctea é menor do que o determinado a partir de dados rádio. Nossos resultados mais recentes sobre o conteúdo estelar de G333.1-0.4 revelaram vários objetos que possuem cores bastante avermelhadas (H-K > 2,0). Nós identificamos estes objetos usando os diagramas cor-cor e cor-magnitude dos aglomerados. Estes objetos apresentam um forte excesso em emissão na banda K e possivelmente se tratam de estrelas do tipo OB envolvidas por um disco/envelope circumestelar espesso. O estudo da função de massa inical desta região, em conjunto com resultados de nossos trabalhos anteriores, aponta para uma IMF independente da posição galática. A contagem de estrelas nos fornece um valor para o número de fótons no contínuo de Lyman que corrobora com a afirmação de que G333.1-0.4 se encontra mais próxima da menor distância determinada por rádio.

  11. Ortho-para-hydrogen equilibration on Jupiter

    NASA Technical Reports Server (NTRS)

    Carlson, Barbara E.; Lacis, Andrew A.; Rossow, William B.

    1992-01-01

    Voyager IRIS observations reveal that the Jovian para-hydrogen fraction is not in thermodynamic equilibrium near the NH3 cloud top, implying that a vertical gradient exists between the high-temperature equilibrium value of 0.25 at depth and the cloud top values. The height-dependent para-hydrogen profile is obtained using an anisotropic multiple-scattering radiative transfer model. A vertical correlation is found to exist between the location of the para-hydrogen gradient and the NH3 cloud, strongly suggesting that paramagnetic conversion on NH3 cloud particle surfaces is the dominant equilibration mechanism. Below the NH3 cloud layer, the para fraction is constant with depth and equal to the high-temperature equilibrium value of 0.25. The degree of cloud-top equilibration appears to depend on the optical depth of the NH3 cloud layer. Belt-zone variations in the para-hydrogen profile seem to be due to differences in the strength of the vertical mixing.

  12. Direct observation and modelling of ordered hydrogen adsorption and catalyzed ortho-para conversion on ETS-10 titanosilicate material.

    PubMed

    Ricchiardi, Gabriele; Vitillo, Jenny G; Cocina, Donato; Gribov, Evgueni N; Zecchina, Adriano

    2007-06-07

    Hydrogen physisorption on porous high surface materials is investigated for the purpose of hydrogen storage and hydrogen separation, because of its simplicity and intrinsic reversibility. For these purposes, the understanding of the binding of dihydrogen to materials, of the structure of the adsorbed phase and of the ortho-para conversion during thermal and pressure cycles are crucial for the development of new hydrogen adsorbents. We report the direct observation by IR spectroscopic methods of structured hydrogen adsorption on a porous titanosilicate (ETS-10), with resolution of the kinetics of the ortho-para transition, and an interpretation of the structure of the adsorbed phase based on classical atomistic simulations. Distinct infrared signals of o- and p-H2 in different adsorbed states are measured, and the conversion of o- to p-H2 is monitored over a timescale of hours, indicating the presence of a catalyzed reaction. Hydrogen adsorption occurs in three different regimes characterized by well separated IR manifestations: at low pressures ordered 1:1 adducts with Na and K ions exposed in the channels of the material are formed, which gradually convert into ordered 2:1 adducts. Further addition of H2 occurs only through the formation of a disordered condensed phase. The binding enthalpy of the Na+-H2 1:1 adduct is of -8.7+/-0.1 kJ mol(-1), as measured spectroscopically. Modeling of the weak interaction of H2 with the materials requires an accurate force field with a precise description of both dispersion and electrostatics. A novel three body force field for molecular hydrogen is presented, based on the fitting of an accurate PES for the H2-H2 interaction to the experimental dipole polarizability and quadrupole moment. Molecular mechanics simulations of hydrogen adsorption at different coverages confirm the three regimes of adsorption and the structure of the adsorbed phase.

  13. An In Vitro Spectroscopic Analysis to Determine Whether para-Chloroaniline is Produced from Mixing Sodium Hypochlorite and Chlorhexidine

    PubMed Central

    Thomas, John E.; Sem, Daniel S.

    2009-01-01

    Introduction The purpose of this in vitro study was to determine whether para-chloroaniline (PCA) is formed through the reaction of mixing sodium hypochlorite (NaOCl) and chlorhexidine (CHX). Methods Initially commercially available samples of chlorhexidine acetate (CHXa) and PCA were analyzed with 1H NMR spectroscopy. Two solutions, NaOCl and CHXa, were warmed to 37°C and when mixed they produced a brown precipitate. This precipitate was separated in half and pure PCA was added to one of the samples for comparison before they were each analyzed with 1H NMR spectroscopy. Results The peaks in the 1H NMR spectra of CHXa and PCA were assigned to specific protons of the molecules, and the location of the aromatic peaks in the PCA spectrum defined the PCA doublet region. While the spectrum of the precipitate alone resulted in a complex combination of peaks, upon magnification there were no peaks in the PCA doublet region which were intense enough to be quantified. In the spectrum of the precipitate, to which PCA was added, two peaks do appear in the PCA doublet region. Comparing this spectrum to that of precipitate alone, the peaks in the PCA doublet region are not visible prior to the addition of PCA. Conclusions Based on this in vitro study, the reaction mixture of NaOCl and CHXa does not produce PCA at any measurable quantity and further investigation is needed to determine the chemical composition of the brown precipitate. PMID:20113799

  14. Na+-dependent and Na+-independent betaine transport across the apical membrane of rat renal epithelium.

    PubMed

    Cano, Mercedes; Calonge, María L; Ilundáin, Anunciación A

    2015-10-01

    The low renal excretion of betaine indicates that the kidney efficiently reabsorbs the betaine filtered by the glomeruli but the mechanisms involved in such a process have been scarcely investigated. We have detected concentrative and non-concentrative betaine transport activity in brush-border membrane vesicles (BBMV) from rat renal cortex and medulla. The concentrative system is the Sodium/Imino-acid Transporter 1 (SIT1) because it is Na+- and Cl--dependent, electrogenic and is inhibited by an anti-SIT1 antibody. Its apparent affinity constant for betaine, Kt, is 1.1±0.5 mM and its maximal transport velocity, Vmax, 0.5±0.1 nmol betaine/mg protein/s. Inhibitors of the Na+/Cl-/betaine uptake are L-proline (75%) and cold betaine, L-carnitine and choline (40-60%). Neither creatine, TEA, taurine, β-alanine, GABA nor glycine significantly inhibited Na+/Cl-/betaine uptake. The non-concentrative betaine transport system is Na+- and H+-independent, electroneutral, with a Kt for betaine of 47±7 μM and a Vmax of 7.8±1 pmol betaine/mg protein/s. Its transport activity is nearly abolished by betaine, followed by L-carnitine (70-80%) and proline (40-50%), but a difference from the Na+/Cl-/betaine transport is that it is inhibited by TEA (approx. 50%) and unaffected by choline. The underlying carrier functions as an antiporter linking betaine entry into the BBMV with the efflux of either L-carnitine or betaine, an exchange unaffected by the anti-SIT1 antibody. As far as we know this is the first work reporting that betaine crosses the apical membrane of rat renal epithelium by SIT1 and by a Na+- and H+-independent transport system. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Fabrication of Na0.7MnO2/C composite cathode material by simple heat treatment for high-power na-ion batteries

    NASA Astrophysics Data System (ADS)

    Sohn, DongRak; Lim, Sung-Jin; Nam, Do-Hwan; Hong, Kyung-Sik; Kim, Tae-Hee; Oh, SeKwon; Eom, Ji-Yong; Cho, EunAe; Kwon, HyukSang

    2018-01-01

    A Na0.7MnO2/C composite cathode material is synthesized by simple and costeffective two-step heat treatment for an improvement in the rate capability of Na0.7MnO2. The first heat treatment is to synthesize Na0.7MnO2, and the second one is a low temperature annealing at 350 °C for 1 h in air, which is necessary to suppress an interfacial reaction between the Na0.7MnO2 and C in the synthesis process of Na0.7MnO2/C composite. Structural analyses by XRD and XPS reveal that the Na0.7MnO2/C shows the same structural properties as that of the pristine Na0.7MnO2, and hence they exhibit the same initial discharge capacity of 175 mAh g-1 at 20 mA g-1. At a current density of 400 mA g-1, the discharge capacity of Na0.7MnO2 reduces to 50 mAh g-1 (28% of the initial discharge capacity), whereas that of Na0.7MnO2/C reduces to 108 mAh g-1 (61% of the initial discharge capacity). The enhanced rate capability of the Na0.7MnO2/C is attributed to the conductive carbon layer formed on the surface of Na0.7MnO2 particles, enabling the facile transport of electrons from the current collector to the surface of the Na0.7MnO2 particles. [Figure not available: see fulltext.

  16. Dramatic increase in naïve T cell turnover is linked to loss of naïve T cells from old primates

    PubMed Central

    Čičin-Šain, Luka; Messaoudi, Ilhem; Park, Byung; Currier, Noreen; Planer, Shannon; Fischer, Miranda; Tackitt, Shane; Nikolich-Žugich, Dragana; Legasse, Alfred; Axthelm, Michael K.; Picker, Louis J.; Mori, Motomi; Nikolich-Žugich, Janko

    2007-01-01

    The loss of naïve T cells is a hallmark of immune aging. Although thymic involution is a primary driver of this naïve T cell loss, less is known about the contribution of other mechanisms to the depletion of naïve T cells in aging primates. We examined the role of homeostatic cycling and proliferative expansion in different T cell subsets of aging rhesus macaques (RM). BrdU incorporation and the expression of the G1-M marker Ki-67 were elevated in peripheral naïve CD4 and even more markedly in the naïve CD8 T cells of old, but not young adult, RM. Proliferating naïve cells did not accumulate in old animals. Rather, the relative size of the naïve CD8 T cell compartment correlated inversely to its proliferation rate. Likewise, T cell receptor diversity decreased in individuals with elevated naïve CD8 T cell proliferation. This apparent contradiction was explained by a significant increase in turnover concomitant with the naïve pool loss. The turnover increased exponentially when the naïve CD8 T cell pool decreased below 4% of total blood CD8 cells. These results link the shrinking naïve T cell pool with a dramatic increase in homeostatic turnover, which has the potential to exacerbate the progressive exhaustion of the naïve pool and constrict the T cell repertoire. Thus, homeostatic T cell proliferation exhibits temporal antagonistic pleiotropy, being beneficial to T cell maintenance in adulthood but detrimental to the long-term T cell maintenance in aging individuals. PMID:18056811

  17. 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.

  18. Modulation of contraction by intracellular Na+ via Na(+)-Ca2+ exchange in single shark (Squalus acanthias) ventricular myocytes.

    PubMed Central

    Näbauer, M; Morad, M

    1992-01-01

    1. The effect of direct alteration of intracellular Na+ concentration on contractile properties of whole-cell clamped shark ventricular myocytes was studied using an array of 256 photodiodes to monitor the length of the isolated myocytes. 2. In myocytes dialysed with Na(+)-free solution, the voltage dependence of Ca2+ current (ICa) and contraction were similar and bell shaped. Contractions activated at all voltages were completely suppressed by nifedipine (5 microM), and failed to show significant tonic components, suggesting dependence of the contraction on Ca2+ influx through the L-type Ca2+ channel. 3. In myocytes dialysed with 60 mM Na+, a ICa-dependent and a ICa-independent component of contraction could be identified. The Ca2+ current-dependent component was prominent in voltages between -30 to +10 mV. The ICa-independent contractions were maintained for the duration of depolarization, increased with increasing depolarization between +10 to +100 mV, and were insensitive to nifedipine. 4. In such myocytes, repolarization produced slowly decaying inward tail currents closely related to the time course of relaxation and the degree of shortening prior to repolarization. 5. With 60 mM Na+ in the pipette solution, positive clamp potentials activated decaying outward currents which correlated to the size of contraction. These outward currents appeared to be generated by the Na(+)-Ca(2+)-exchanger since they depended on the presence of intracellular Na+, and were neither suppressed by nifedipine nor by K+ channel blockers. 6. The results suggest that in shark (Squalus acanthias) ventricular myocytes, which lack functionally relevant Ca2+ release pools, both Ca2+ channel and the Na(+)-Ca2+ exchanger deliver sufficient Ca2+ to activate contraction, though the effectiveness of the latter mechanism was highly dependent on the [Na+]i. PMID:1338467

  19. Hot-corrosion of AISI 1020 steel in a molten NaCl/Na2SO4 eutectic at 700°C

    NASA Astrophysics Data System (ADS)

    Badaruddin, Mohammad; Risano, Ahmad Yudi Eka; Wardono, Herry; Asmi, Dwi

    2017-01-01

    Hot-corrosion behavior and morphological development of AISI 1020 steel with 2 mg cm-2 mixtures of various NaCl/Na2SO4 ratios at 700°C were investigated by means of weight gain measurements, Optical Microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The weight gain kinetics of the steel with mixtures of salt deposits display a rapid growth rates, compared with the weight gain kinetics of AISI 1020 steel without salt deposit in dry air oxidation, and follow a steady-state parabolic law for 49 h. Chloridation and sulfidation produced by a molten NaCl/Na2SO4 on the steel induced hot-corrosion mechanism attack, and are responsible for the formation of thicker scale. The most severe corrosion takes place with the 70 wt.% NaCl mixtures in Na2SO4. The typical Fe2O3 whisker growth in outer part scale was attributed to the FeCl3 volatilization. The formation of FeS in the innermost scale is more pronounced as the content of Na2SO4 in the mixture is increased.

  20. Regulation of Epithelial Sodium Transport via Epithelial Na+ Channel

    PubMed Central

    Marunaka, Yoshinori; Niisato, Naomi; Taruno, Akiyuki; Ohta, Mariko; Miyazaki, Hiroaki; Hosogi, Shigekuni; Nakajima, Ken-ichi; Kusuzaki, Katsuyuki; Ashihara, Eishi; Nishio, Kyosuke; Iwasaki, Yoshinobu; Nakahari, Takashi; Kubota, Takahiro

    2011-01-01

    Renal epithelial Na+ transport plays an important role in homeostasis of our body fluid content and blood pressure. Further, the Na+ transport in alveolar epithelial cells essentially controls the amount of alveolar fluid that should be kept at an appropriate level for normal gas exchange. The epithelial Na+ transport is generally mediated through two steps: (1) the entry step of Na+ via epithelial Na+ channel (ENaC) at the apical membrane and (2) the extrusion step of Na+ via the Na+, K+-ATPase at the basolateral membrane. In general, the Na+ entry via ENaC is the rate-limiting step. Therefore, the regulation of ENaC plays an essential role in control of blood pressure and normal gas exchange. In this paper, we discuss two major factors in ENaC regulation: (1) activity of individual ENaC and (2) number of ENaC located at the apical membrane. PMID:22028593

  1. Tiempo para un cambio

    NASA Astrophysics Data System (ADS)

    Woltjer, L.

    1987-06-01

    En la reunion celebrada en diciembre dei ano pasado informe al Consejo de mi deseo de terminar mi contrato como Director General de la ESO una vez que fuera aprobado el proyecto dei VLT, que se espera sucedera hacia fines de este aAo. Cuando fue renovada mi designacion hace tres aAos, el Consejo conocia mi intencion de no completar los cinco aAos dei contrato debido a mi deseo de disponer de mas tiempo para otras actividades. Ahora, una vez terminada la fase preparatoria para el VLT, Y habiendose presentado el proyecto formalmente al Consejo el dia 31 de marzo, y esperando su muy probable aprobacion antes dei termino de este ano, me parece que el 10 de enero de 1988 presenta una excelente fecha para que se produzca un cambio en la administracion de la ESO.

  2. Multiple quantum filtered 23Na NMR in the Langendorff perfused mouse heart: Ratio of triple/double quantum filtered signals correlates with [Na]i

    PubMed Central

    Eykyn, Thomas R.; Aksentijević, Dunja; Aughton, Karen L.; Southworth, Richard; Fuller, William; Shattock, Michael J.

    2015-01-01

    We investigate the potential of multiple quantum filtered (MQF) 23Na NMR to probe intracellular [Na]i in the Langendorff perfused mouse heart. In the presence of Tm(DOTP) shift reagent the triple quantum filtered (TQF) signal originated largely from the intracellular sodium pool with a 32 ± 6% contribution of the total TQF signal arising from extracellular sodium, whilst the rank 2 double-quantum filtered signal (DQF), acquired with a 54.7° flip-angle pulse, originated exclusively from the extracellular sodium pool. Given the different cellular origins of the 23Na MQF signals we propose that the TQF/DQF ratio can be used as a semi-quantitative measure of [Na]i in the mouse heart. We demonstrate a good correlation of this ratio with [Na]i measured with shift reagent at baseline and under conditions of elevated [Na]i. We compare the measurements of [Na]i using both shift reagent and TQF/DQF ratio in a cohort of wild type mouse hearts and in a transgenic PLM3SA mouse expressing a non-phosphorylatable form of phospholemman, showing a modest but measurable elevation of baseline [Na]i. MQF filtered 23Na NMR is a potentially useful tool for studying normal and pathophysiological changes in [Na]i, particularly in transgenic mouse models with altered Na regulation. PMID:26196304

  3. The Dammam aquifer in Bahrain - Hydrochemical characterization and alternatives for management of groundwater quality

    NASA Astrophysics Data System (ADS)

    Zubari, Waleed K.

    orientale. Quatre types de salinisation de l'eau souterraine ont été identifiés : une drainance verticale en provenance d'eaux saumâtres sous-jacentes dans les régions nord-centrales, ouest et est, une intrusion marine dans la région est, une intrusion d'eau de sebkha dans la région sud-ouest, et le retour d'irrigation dans un secteur localisé de la région sud-ouest. Quatre démarches alternatives de gestion de la qualité des eaux souterraines, acceptables par les services chargés de l'eau à Bahreïn, sont discutées et des zones d'action prioritaire sont proposées, selon le type et l'étendue de chacune des sources de salinisation et en fonction des usages de les eaux souterraines dans chaque secteur. L'efficacité des options de gestion proposées pour le contrôle de la dégradation de la qualité de l'aquifère de Damman devrait être ensuite évaluée au moyen d'un modèle de simulation. Resumen El acuífero de Damman, el más importante de Bahrein, se explota para usos agrícolas y domésticos. La sobreexplotación del mismo ha provocado su salinización por cuerpos de agua salada y salobre cercanos. Un estudio hidroquímico identificó las fuentes de salinización y ayudó a dibujar sus áreas de influencia. La calidad del agua subterránea se modifica significativamente en la dirección del flujo, desde el noroeste del país, donde las entradas son laterales y procedentes de Arabia Saudí, hacia el sur y el sudeste. Se han identificado cuatro tipos de salinización: flujo ascendente de agua salobre en las regiones norte-central, este y oeste; intrusión de agua marina en la región este; intrusión de agua salobre al sudoeste y, finalmente, retorno de riego en un área local de la región oeste. Se discuten cuatro alternativas para la gestión del agua y se proponen áreas prioritarias basadas en el tipo y la extensión de cada fuente de salinización y en los usos de agua subterránea en cada zona. La efectividad de las opciones de gestión propuestas

  4. Hydrogen production by sodium borohydride in NaOH aqueous solution

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Zhang, L. F.; Zhao, Z. G.

    2018-01-01

    The kinetics of hydrolysis reaction of NaBH4 in NaOH aqueous solution is studied. The influence of pH of the NaOH aqueous solution on the rate of hydrogen production and the hydrogen production efficiency are studied for the hydrolysis reaction of NaBH4. The results show that the activation energy of hydrolysis reaction of NaBH4 increased with the increase of the initial pH of NaOH aqueous solution.With the increasing of the initial pH of NaOH aqueous solution, the rate of hydrogen production and hydrogen production efficiency of NaBH4 hydrolysis decrease.

  5. Nonclassical and semiclassical para-Bose states

    NASA Astrophysics Data System (ADS)

    Huerta Alderete, C.; Villanueva Vergara, Liliana; Rodríguez-Lara, B. M.

    2017-04-01

    Motivated by the proposal to simulate para-Bose oscillators in a trapped-ion setup [C. Huerta Alderete and B. M. Rodríguez-Lara, Phys. Rev. A 95, 013820 (2017), 10.1103/PhysRevA.95.013820], we introduce an overcomplete, nonorthogonal basis for para-Bose Hilbert spaces. The states spanning these bases can be experimentally realized in the trapped-ion simulation via time evolution. The para-Bose states show both nonclassical and semiclassical statistics on their Fock state distribution, asymmetric field quadrature variances, and do not minimize the uncertainty relation for the field quadratures. These properties are analytically controlled by the para-Bose order and the evolution time; both parameters might be feasible for fine tuning in the trapped-ion quantum simulation.

  6. Otimização de procedimento de manobra para indução de reentrada de um satélite retornável

    NASA Astrophysics Data System (ADS)

    Schulz, W.; Suarez, M.

    2003-08-01

    Veículos espaciais que retornam à Terra passam por regimes de velocidade e condições de vôo distintos. Estas diferenças dificultam sua concepção aerodinâmica e o planejamento de seu retorno. A partir de uma proposta de um veículo orbital retornável (satélite SARA, em desenvolvimento no IAE/CTA) para realização de experimentos científicos e tecnológicos em ambiente de baixa gravidade, surge a necessidade de realizarem-se estudos considerando-se os aspectos relativos à sua aerodinâmica. Após o lançamento, o veículo deve permanecer em órbita pelo tempo necessário para a condução de experimentos, sendo depois direcionado à Terra e recuperado em solo. A concepção aerodinâmica é de importância para o vôo em suas diversas fases e deve considerar aspectos relativos à estabilização Aerodinâmica e ao arrasto atmosférico, sendo este último de importância crucial na análise do aquecimento a ser enfrentado. A manobra de retorno inclui considerações sobre as condições atmosféricas e dinâmica de reentrada, devendo ser calculada de forma mais precisa possível. O trabalho proposto avalia estudos da dinâmica de vôo de um satélite recuperável considerando aspectos relativos à determinação orbital com GPS, técnica utilizada com sucesso na CONAE, e seu comportamento aerodinâmico em vôo balístico de retorno, com ênfase em sua fase de reentrada atmosférica. Busca-se otimizar a manobra de reentrada de tal forma que a utilização do sistema GPS garanta minimizar a área de impacto com o solo.

  7. Coulomb excitation of radioactive 20, 21Na

    NASA Astrophysics Data System (ADS)

    Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

    2009-12-01

    The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ˜ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for γ -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( λ L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ↓ value for 21Na is 137±9 e^2fm^4, while the resulting B( λ L) ↓ values for 20Na are 55±6 e^2fm^4 for the 3+ rightarrow 2+ , 35.7±5.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.154±0.030 μ_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( λ L) values for the proton dripline nucleus 20Na .-1

  8. Detailed investigation of Na2.24FePO4CO3 as a cathode material for Na-ion batteries

    PubMed Central

    Huang, Weifeng; Zhou, Jing; Li, Biao; Ma, Jin; Tao, Shi; Xia, Dingguo; Chu, Wangsheng; Wu, Ziyu

    2014-01-01

    Na-ion batteries are gaining an increased recognition as the next generation low cost energy storage devices. Here, we present a characterization of Na3FePO4CO3 nanoplates as a novel cathode material for sodium ion batteries. First-principles calculations reveal that there are two paths for Na ion migration along b and c axis. In-situ and ex-situ Fe K-edge X-ray absorption near edge structure (XANES) point out that in Na3FePO4CO3 both Fe2+/Fe3+ and Fe3+/Fe4+ redox couples are electrochemically active, suggesting also the existence of a two-electron intercalation reaction. Ex-situ X-ray powder diffraction data demonstrates that the crystalline structure of Na3FePO4CO3 remains stable during the charging/discharging process within the range 2.0–4.55 V. PMID:24595232

  9. Biphasic voltage-dependent inactivation of human NaV 1.3, 1.6 and 1.7 Na+ channels expressed in rodent insulin-secreting cells.

    PubMed

    Godazgar, Mahdieh; Zhang, Quan; Chibalina, Margarita V; Rorsman, Patrik

    2018-05-01

    Na + current inactivation is biphasic in insulin-secreting cells, proceeding with two voltage dependences that are half-maximal at ∼-100 mV and -60 mV. Inactivation of voltage-gated Na + (Na V ) channels occurs at ∼30 mV more negative voltages in insulin-secreting Ins1 and primary β-cells than in HEK, CHO or glucagon-secreting αTC1-6 cells. The difference in inactivation between Ins1 and non-β-cells persists in the inside-out patch configuration, discounting an involvement of a diffusible factor. In Ins1 cells and primary β-cells, but not in HEK cells, inactivation of a single Na V subtype is biphasic and follows two voltage dependences separated by 30-40 mV. We propose that Na V channels adopt different inactivation behaviours depending on the local membrane environment. Pancreatic β-cells are equipped with voltage-gated Na + channels that undergo biphasic voltage-dependent steady-state inactivation. A small Na + current component (10-15%) inactivates over physiological membrane potentials and contributes to action potential firing. However, the major Na + channel component is completely inactivated at -90 to -80 mV and is therefore inactive in the β-cell. It has been proposed that the biphasic inactivation reflects the contribution of different Na V α-subunits. We tested this possibility by expression of TTX-resistant variants of the Na V subunits found in β-cells (Na V 1.3, Na V 1.6 and Na V 1.7) in insulin-secreting Ins1 cells and in non-β-cells (including HEK and CHO cells). We found that all Na V subunits inactivated at 20-30 mV more negative membrane potentials in Ins1 cells than in HEK or CHO cells. The more negative inactivation in Ins1 cells does not involve a diffusible intracellular factor because the difference between Ins1 and CHO persisted after excision of the membrane. Na V 1.7 inactivated at 15--20 mV more negative membrane potentials than Na V 1.3 and Na V 1.6 in Ins1 cells but this small difference is insufficient to solely

  10. Associação entre sintomas, veias varicosas e refluxo na veia safena magna ao eco-Doppler

    PubMed Central

    Seidel, Amélia Cristina; Campos, Mariana Baldini; Campos, Raquel Baldini; Harada, Dérica Sayuri; Rossi, Robson Marcelo; Cavalari, Pedro; Miranda, Fausto

    2017-01-01

    Resumo Contexto A doença venosa crônica requer avaliação clínica, quantificação dos efeitos hemodinâmicos e definição da distribuição anatômica para decisão diagnóstica e tratamento. Métodos Estudo prospectivo realizado em 2015 com amostra de 1.384 pacientes (2.669 membros) com idade entre 17 e 85 anos, sendo 1.227 do sexo feminino. Nas respostas do questionário aplicado, os sintomas pesquisados eram dor, cansaço, sensação de peso, queimação, câimbras e formigamento. Para a formação dos grupos, foi considerado o número de membros, distribuídos em relação ao gênero, ao índice de massa corporal e à idade. Após a definição grupos e a realização do eco-Doppler para estudo da veia safena magna (VSM), os pacientes foram distribuídos em três grupos (I: sintomas presentes e varizes ausentes, II: sintomas ausentes e varizes presentes e III: sintomas presentes e varizes presentes). A análise estatística utilizou o teste qui-quadrado ou exato de Fisher para verificar a homogeneidade entre os grupos. Em caso de associação com significância de 5%, foi calculada a razão de chances. Resultados Para ambos os gêneros, foi observada chance de insuficiência da VSM 11,2 vezes maior no grupo III. Por sua vez, os casos de obesidade mórbida ocorreram 9,1 vezes mais no mesmo grupo. Além disso, pacientes na faixa etária entre 30 e 50 anos desse grupo apresentaram chance de insuficiência da VSM 43,1 vezes maior. Conclusões A insuficiência da VSM foi significantemente mais frequente no grupo III, tanto globalmente como considerando apenas os casos de obesidade mórbida e a faixa etária mais elevada. PMID:29930616

  11. A neural network potential energy surface for the NaH2 system and dynamics studies on the H(2S) + NaH(X1Σ+) → Na(2S) + H2(X1Σg+) reaction.

    PubMed

    Wang, Shufen; Yuan, Jiuchuang; Li, Huixing; Chen, Maodu

    2017-08-02

    In order to study the dynamics of the reaction H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ), a new potential energy surface (PES) for the ground state of the NaH 2 system is constructed based on 35 730 ab initio energy points. Using basis sets of quadruple zeta quality, multireference configuration interaction calculations with Davidson correction were carried out to obtain the ab initio energy points. The neural network method is used to fit the PES, and the root mean square error is very small (0.00639 eV). The bond lengths, dissociation energies, zero-point energies and spectroscopic constants of H 2 (X 1 Σ g + ) and NaH(X 1 Σ + ) obtained on the new NaH 2 PES are in good agreement with the experiment data. On the new PES, the reactant coordinate-based time-dependent wave packet method is applied to study the reaction dynamics of H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ), and the reaction probabilities, integral cross-sections (ICSs) and differential cross-sections (DCSs) are obtained. There is no threshold in the reaction due to the absence of an energy barrier on the minimum energy path. When the collision energy increases, the ICSs decrease from a high value at low collision energy. The DCS results show that the angular distribution of the product molecules tends to the forward direction. Compared with the LiH 2 system, the NaH 2 system has a larger mass and the PES has a larger well at the H-NaH configuration, which leads to a higher ICS value in the H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ) reaction. Because the H( 2 S) + NaH(X 1 Σ + ) → Na( 2 S) + H 2 (X 1 Σ g + ) reaction releases more energy, the product molecules can be excited to a higher vibrational state.

  12. The NA62 trigger system

    NASA Astrophysics Data System (ADS)

    Krivda, M.; NA62 Collaboration

    2013-08-01

    The main aim of the NA62 experiment (NA62 Technical Design Report, na62.web.cern.ch/NA62/Documents/TD_Full_doc_v1.pdf> [1]) is to study ultra-rare Kaon decays. In order to select rare events over the overwhelming background, central systems with high-performance, high bandwidth, flexibility and configurability are necessary, that minimize dead time while maximizing data collection reliability. The NA62 experiment consists of 12 sub-detector systems and several trigger and control systems, for a total channel count of less than 100,000. The GigaTracKer (GTK) has the largest number of channels (54,000), and the Liquid Krypton (LKr) calorimeter shares with it the largest raw data rate (19 GB/s). The NA62 trigger system works with 3 trigger levels. The first trigger level is based on a hardware central trigger unit, so-called L0 Trigger Processor (L0TP), and Local Trigger Units (LTU), which are all located in the experimental cavern. Other two trigger levels are based on software, and done with a computer farm located on surface. The L0TP receives information from triggering sub-detectors asynchronously via Ethernet; it processes the information, and then transmits a final trigger decision synchronously to each sub-detector through the Trigger and Timing Control (TTC) system. The interface between L0TP and the TTC system, which is used for trigger and clock distribution, is provided by the Local Trigger Unit board (LTU). The LTU can work in two modes: global and stand-alone. In the global mode, the LTU provides an interface between L0TP and TTC system. In the stand-alone mode, the LTU can fully emulate L0TP and so provides an independent way for each sub-detector for testing or calibration purposes. In addition to the emulation functionality, a further functionality is implemented that allows to synchronize the clock of the LTU with the L0TP and the TTC system. For testing and debugging purposes, a Snap Shot Memory (SSM) interface is implemented, that can work

  13. Na7 [Fe2S6 ] , Na2 [FeS2 ] and Na2 [FeSe2 ] : New 'reduced' sodium chalcogenido ferrates

    NASA Astrophysics Data System (ADS)

    Stüble, Pirmin; Peschke, Simon; Johrendt, Dirk; Röhr, Caroline

    2018-02-01

    Three new 'reduced' FeII containing sodium chalcogenido ferrates were obtained applying a reductive synthetic route. The mixed-valent sulfido ferrate Na7 [Fe2S6 ] , which forms bar-shaped crystals with metallic greenish luster, was synthesized in pure phase from natural pyrite and elemental sodium at a maximum temperature of 800 °C. Its centrosymmetric triclinic structure (SG P 1 bar , a = 764.15(2), b = 1153.70(2), c = 1272.58(3) pm, α = 62.3325 (7) , β = 72.8345 (8) , γ = 84.6394 (8) ° , Z = 3, R1 = 0.0185) exhibits two crystallographically different [Fe2S6 ] 7 - dimers of edge-sharing [FeS4 ] tetrahedra, with somewhat larger Fe-S distances than in the fully oxidized FeIII dimers of e.g. Na6 [Fe2III S6 ] . In contrast to the localized AFM ordered pure di-ferrates(III), the Curie-Weiss behavior of the magnetic susceptibility proves the rarely observed valence-delocalized S = 9/2 state of the mixed-valent FeIII /FeII dimer. The nearly spin-only value of the magnetic moment combined with the chemical bonding not generally differing from that in pure ferrates(II) and (III), provides a striking argument, that the reduction of the local Fe spin moments observed in all condensed sulfido ferrate moieties is connected with the AFM spin ordering. The two isotypic ferrates(II) Na2 [FeS2 ] and Na2 [FeSe2 ] with chain-like structural units (SG Ibam, a = 643.54(8)/ 660.81(1), b = 1140.2(2)/1190.30(2) c = 562.90(6)/585.59(1) pm, Z = 4, R1 = 0.0372/0.0466) crystallize in the K2 [ZnO2 ] -type structure. Although representing merely further members of the common series of chalcogenido metallates(II) Na2 [MIIQ2 ] , these two new phases, together with Na6 [FeS4 ] and Li2 [FeS2 ] , are the only examples of pure FeII alkali chalcogenido ferrates. The new compounds allow for a general comparison of di- and chain ferrates(II) and (III) and mixed-valent analogs concerning the electronic and magnetic properties (including Heisenberg super-exchange and double-exchange interactions

  14. Patterns in groundwater chemistry resulting from groundwater flow

    NASA Astrophysics Data System (ADS)

    Stuyfzand, Pieter J.

    qualité de l'eau vers une absence de fluctuations, de polluées vers non polluées, d'acides vers basiques, d'oxygénées vers anoxiques et méthanogènes, depuis des échanges de base inexistants vers des échanges significatifs, de l'eau douce vers l'eau saumâtre. Ceci est montré pour une nappe d'eau douce dans une dune côtière des Pays-Bas. Dans "l'hydrosome", on montre que la disparition du carbonate de calcium par lessivage à plus de 15m et celle de cations adsorbés d'origine marine (Na+, K+ et Mg2+) à plus de 2500m vers l'aval-gradient correspond à environ 5000 ans d'écoulement, depuis que la barrière de la plage avec les dunes s'est mise en place. Les zones d'alimentation ponctuelle dans les dunes sont mises en évidence par l'eau souterraine montrant une plus faible évolution prograde de sa qualité que l'eau souterraine de la dune alentour. L'eau du Rhin utilisée pour la réalimentation artificielle dans les dunes a fourni des types hydrochimiques distincts, qui marquent l'écoulement, le mélange et les âges de l'eau souterraine. Resumen El flujo subterráneo tiene una gran importancia sobre la hidroquímica de un sistema ya que reduce la mezcla por difusión, transporta las huellas químicas y biológicas de las acciones antrópicas en la zona de recarga y drena el sistema acuífero. Las tendencias globales vienen regidas por las diferencias en el flujo de agua meteórica que atraviesa el subsuelo. En un hidrosoma individual (cuerpo de agua de un origen específico), se suele desarrollar la siguiente línea de evolución (secuencia de facies) en la dirección del flujo: de gran a nula fluctuación en la calidad del agua, de agua contaminada a no contaminada, de ácida a básica, de óxica a anóxica-metanogénica, de nulo a importante cambio de base y de agua dulce a salobre. Esto puede verse, por ejemplo, en las aguas dulces presentes en las dunas costeras de Holanda. En este hidrosoma, el lixiviado de carbonato cálcico, hasta 15m, y de

  15. Ranolazine vs phenytoin: greater effect of ranolazine on the transient Na(+) current than on the persistent Na(+) current in central neurons.

    PubMed

    Terragni, Benedetta; Scalmani, Paolo; Colombo, Elisa; Franceschetti, Silvana; Mantegazza, Massimo

    2016-11-01

    Voltage-gated Na(+) channels (NaV) are involved in pathologies and are important targets of drugs (NaV-blockers), e.g. some anti-epileptic drugs (AEDs). Besides the fast inactivating transient Na(+) current (INaT), they generate a slowly inactivating "persistent" current (INaP). Ranolazine, a NaV-blocker approved for treatment of angina pectoris, is considered a preferential inhibitor of INaP and has been proposed as a novel AED. Although it is thought that classic NaV-blockers used as AEDs target mainly INaT, they can also reduce INaP. It is important to disclose specific features of novel NaV-blockers, which could be necessary for their effect as AEDs in drug resistant patients. We have compared the action of ranolazine and of the classic AED phenytoin in transfected cells expressing the neuronal NaV1.1 Na(+) channel and in neurons of neocortical slices. Our results show that the relative block of INaT versus INaP of ranolazine and phenytoin is variable and depends on Na(+) current activation conditions. Strikingly, ranolazine blocks with less efficacy INaP and more efficacy INaT than phenytoin in conditions mimicking pathological states (i.e. high frequency firing and long lasting depolarizations). The effects are consistent with binding of ranolazine to both open/pre-open and inactivated states; larger INaT block at high stimulation frequencies is caused by the induction of a slow inactivated state. Thus, contrary than expected, ranolazine is not a better INaP blocker than phenytoin in central neurons, and phenytoin is not a better INaT blocker than ranolazine. Nevertheless, they show a complementary action and could differentially target specific pathological dysfunctions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. 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.

  17. Na2O-Al2O3 system: Activity of Na2O in (α + β)- and (β + β)-alumina

    NASA Astrophysics Data System (ADS)

    Kale, G. M.

    1992-12-01

    The activity of Na2O in a biphasic mixture of (α + β)-alumina has been measured in the temperature range of 700 to 1100 K using the solid-state galvanic cell: 11663_2007_Article_BF02656462_TeX2GIFE1.gif _{(1:1)}^{Pt,CO_2 + O_2 /Na_2 CO_3 /(α + β ) - alumin a//(Y_2 O_3 )ZrO_2 //In + In_2 O_3 ,Ta,Pt} Similarly, the activity of Na2O in a (β + β’’)-alumina two-phase mixture has been measured between 700 and 1100 K employing the galvanic cell: 11663_2007_Article_BF02656462_TeX2GIFE2.gif _{(1:1)}^{Pt,CO_2 + O_2 /Na_2 CO_3 /(β + β ) - alumin a//(Y_2 O_3 )ZrO_2 //In + In_2 O_3 ,Ta,Pt} The reversible electromotive force (emf ) of both the cells was found to vary linearly with temperature over the entire temperature range of measurement. From the measured reversible emf and auxiliary thermodynamic data for In2O2, Na2O, CO2 and Na2CO3 reported in the literature, the temperature dependence of the logarithm of activity of Na2O in (α + β)-alumina is obtained: 11663_2007_Article_BF02656462_TeX2GIFE3.gif log α _{Na_2 O} (α + β ) = 1.85 - 14,750/T(K)( ± 0.015)(700 ≤slant T ≤slant 1100) For (β + β'’)-alumina, 11663_2007_Article_BF02656462_TeX2GIFE4.gif log α _{Na_2 O} (β + β ) = 3.9 - 13,000/T(K)( ± 0.015)(700 ≤slant T ≤slant 1100)

  18. Redetermination of Na(3)TaF(8).

    PubMed

    Langer, Vratislav; Smrcok, Lubomír; Boca, Miroslav

    2010-09-01

    The crystal structure of trisodium octafluoridotantalate, Na(3)TaF(8), has been redetermined using diffractometer data collected at 153 K, resulting in more accurate bond distances and angles than obtained from a previous structure determination based on film data. The structure is built from layers running along [101], which are formed by distorted [TaF(8)] antiprisms and [NaF(6)] rectangular bipyramids sharing edges and corners. The individual layers are separated by eight-coordinated Na ions. Two atoms in the asymmetric unit are in special positions: the Ta atom is on a twofold axis in Wyckoff position 4e and one of the Na ions lies on an inversion centre in Wyckoff site 4d.

  19. Na+/H+ exchange activity in the plasma membrane of Arabidopsis.

    PubMed

    Qiu, Quan-Sheng; Barkla, Bronwyn J; Vera-Estrella, Rosario; Zhu, Jian-Kang; Schumaker, Karen S

    2003-06-01

    In plants, Na+/H+ exchangers in the plasma membrane are critical for growth in high levels of salt, removing toxic Na+ from the cytoplasm by transport out of the cell. The molecular identity of a plasma membrane Na+/H+ exchanger in Arabidopsis (SOS1) has recently been determined. In this study, immunological analysis provided evidence that SOS1 localizes to the plasma membrane of leaves and roots. To characterize the transport activity of this protein, purified plasma membrane vesicles were isolated from leaves of Arabidopsis. Na+/H+ exchange activity, monitored as the ability of Na to dissipate an established pH gradient, was absent in plants grown without salt. However, exchange activity was induced when plants were grown in 250 mm NaCl and increased with prolonged salt exposure up to 8 d. H+-coupled exchange was specific for Na, because chloride salts of other monovalent cations did not dissipate the pH gradient. Na+/H+ exchange activity was dependent on Na (substrate) concentration, and kinetic analysis indicated that the affinity (apparent Km) of the transporter for Na+ is 22.8 mm. Data from two experimental approaches supports electroneutral exchange (one Na+ exchanged for one proton): (a) no change in membrane potential was measured during the exchange reaction, and (b) Na+/H+ exchange was unaffected by the presence or absence of a membrane potential. Results from this research provide a framework for future studies into the regulation of the plant plasma membrane Na+/H+ exchanger and its relative contribution to the maintenance of cellular Na+ homeostasis during plant growth in salt.

  20. Osmolality- and Na+ -dependent effects of hyperosmotic NaCl solution on contractile activity and Ca2+ cycling in rat ventricular myocytes.

    PubMed

    Ricardo, Rafael A; Bassani, Rosana A; Bassani, José W M

    2008-01-01

    Hypertonic NaCl solutions have been used for small-volume resuscitation from hypovolemic shock. We sought to identify osmolality- and Na(+)-dependent components of the effects of the hyperosmotic NaCl solution (85 mOsm/kg increment) on contraction and cytosolic Ca(2+) concentration ([Ca(2+)](i)) in isolated rat ventricular myocytes. The biphasic change in contraction and Ca(2+) transient amplitude (decrease followed by recovery) was accompanied by qualitatively similar changes in sarcoplasmic reticulum (SR) Ca(2+) content and fractional release and was mimicked by isosmotic, equimolar increase in extracellular [Na(+)] ([Na(+)](o)). Raising osmolality with sucrose, however, augmented systolic [Ca(2+)](i) monotonically without change in SR parameters and markedly decreased contraction amplitude and diastolic cell length. Functional SR inhibition with thapsigargin abolished hyperosmolality effects on [Ca(2+)](i). After 15-min perfusion, both hyperosmotic solutions slowed mechanical relaxation during twitches and [Ca(2+)](i) decline during caffeine-evoked transients, raised diastolic and systolic [Ca(2+)](i), and depressed systolic contractile activity. These effects were greater with sucrose solution, and were not observed after isosmotic [Na(+)](o) increase. We conclude that under the present experimental conditions, transmembrane Na(+) redistribution apparently plays an important role in determining changes in SR Ca(2+) mobilization, which markedly affect contractile response to hyperosmotic NaCl solutions and attenuate the osmotically induced depression of contractile activity.

  1. Double Knockout of the Na+-Driven Cl-/HCO3- Exchanger and Na+/Cl- Cotransporter Induces Hypokalemia and Volume Depletion.

    PubMed

    Sinning, Anne; Radionov, Nikita; Trepiccione, Francesco; López-Cayuqueo, Karen I; Jayat, Maximilien; Baron, Stéphanie; Cornière, Nicolas; Alexander, R Todd; Hadchouel, Juliette; Eladari, Dominique; Hübner, Christian A; Chambrey, Régine

    2017-01-01

    We recently described a novel thiazide-sensitive electroneutral NaCl transport mechanism resulting from the parallel operation of the Cl - /HCO 3 - exchanger pendrin and the Na + -driven Cl - /2HCO 3 - exchanger (NDCBE) in β-intercalated cells of the collecting duct. Although a role for pendrin in maintaining Na + balance, intravascular volume, and BP is well supported, there is no in vivo evidence for the role of NDCBE in maintaining Na + balance. Here, we show that deletion of NDCBE in mice caused only subtle perturbations of Na + homeostasis and provide evidence that the Na + /Cl - cotransporter (NCC) compensated for the inactivation of NDCBE. To unmask the role of NDCBE, we generated Ndcbe/Ncc double-knockout (dKO) mice. On a normal salt diet, dKO and single-knockout mice exhibited similar activation of the renin-angiotensin-aldosterone system, whereas only dKO mice displayed a lower blood K + concentration. Furthermore, dKO mice displayed upregulation of the epithelial sodium channel (ENaC) and the Ca 2+ -activated K + channel BKCa. During NaCl depletion, only dKO mice developed marked intravascular volume contraction, despite dramatically increased renin activity. Notably, the increase in aldosterone levels expected on NaCl depletion was attenuated in dKO mice, and single-knockout and dKO mice had similar blood K + concentrations under this condition. In conclusion, NDCBE is necessary for maintaining sodium balance and intravascular volume during salt depletion or NCC inactivation in mice. Furthermore, NDCBE has an important role in the prevention of hypokalemia. Because NCC and NDCBE are both thiazide targets, the combined inhibition of NCC and the NDCBE/pendrin system may explain thiazide-induced hypokalemia in some patients. Copyright © 2016 by the American Society of Nephrology.

  2. Five ab initio potential energy and dipole moment surfaces for hydrated NaCl and NaF. I. Two-body interactions.

    PubMed

    Wang, Yimin; Bowman, Joel M; Kamarchik, Eugene

    2016-03-21

    We report full-dimensional, ab initio-based potentials and dipole moment surfaces for NaCl, NaF, Na(+)H2O, F(-)H2O, and Cl(-)H2O. The NaCl and NaF potentials are diabatic ones that dissociate to ions. These are obtained using spline fits to CCSD(T)/aug-cc-pV5Z energies. In addition, non-linear least square fits using the Born-Mayer-Huggins potential are presented, providing accurate parameters based strictly on the current ab initio energies. The long-range behavior of the NaCl and NaF potentials is shown to go, as expected, accurately to the point-charge Coulomb interaction. The three ion-H2O potentials are permutationally invariant fits to roughly 20,000 coupled cluster CCSD(T) energies (awCVTZ basis for Na(+) and aVTZ basis for Cl(-) and F(-)), over a large range of distances and H2O intramolecular configurations. These potentials are switched accurately in the long range to the analytical ion-dipole interactions, to improve computational efficiency. Dipole moment surfaces are fits to MP2 data; for the ion-ion cases, these are well described in the intermediate- and long-range by the simple point-charge expression. The performance of these new fits is examined by direct comparison to additional ab initio energies and dipole moments along various cuts. Equilibrium structures, harmonic frequencies, and electronic dissociation energies are also reported and compared to direct ab initio results. These indicate the high fidelity of the new PESs.

  3. Threshold oxygen levels in Na(I) for the formation of NaCrO 2(s) on 18-8 stainless steels from accurate thermodynamic measurements

    NASA Astrophysics Data System (ADS)

    Sreedharan, O. M.; Madan, B. S.; Gnanamoorthy, J. B.

    1983-12-01

    The compound NaCrO 2(s) is an important corrosion product in sodium-cooled LMFBRs. The standard Gibbs energy of formation of NaCrO 2(s) is required for the computation of threshold oxygen levels in Na(1) for the formation of NaCrO 2(s) on 18-8 stainless steels. For this purpose the emf of the galvanic cell: Pt, NaCrO 2, Cr 2O 3, Na 2CrO 4/15 YSZ/O 2 ( P O 2 = 0.21 atm, air), Pt was measured over 784-1012 K to be: (E±4.4)(mV) = 483.67-0.34155 T(K). From this, the standard Gibbs energy of formation of NaCrO 2(s) from the elements ( ΔG f,T0) and from the oxides ( ΔG f,OX,T0) was calculated to be: [ΔG f,T0(NaCrO 2, s)±1.86] (kJ/mol) =-869.98 + 0.18575 T(K) , [ΔG f,OX,T0(NaCr0 2, s)±4.8] (kJ/mol) = -104.25-0.00856 T(K) . The molar heat capacity, C P0, of NaCrO 2(s) was measured by DSC to be (350-600 K): C P0(NaCrO 2, s) (J/K mol) = 27.15 + 0.1247 T (K) , From these data, values of -99.3 kJ/mol and 91.6 J/K mol were computed for ΔH f,2980 and S 2980 of NaCrO 2(s). The internal consistency was checked with the use of enthalpy data on Na 2CrO 4(s). From the standard Gibbs energy of formation of NaCrO 2(s) the equation logC 0(wppm) = 3.9905-3147.6 T(K) was derived, where C 0 is the threshold oxygen level for the formation of NaCrO 2(s) on 18-8 stainless steels.

  4. A Versatile Low Temperature Synthetic Route to Zintl Phase Precursors: Na4Si4, Na4Ge4 and K4Ge4 as Examples

    PubMed Central

    Ma, Xuchu; Xu, Fen; Atkins, Tonya; Goforth, Andrea M.; Neiner, Doinita; Navrotsky, Alexandra; Kauzlarich, Susan M.

    2010-01-01

    Na4Si4 and Na4Ge4 are ideal chemical precursors for inorganic clathrate structures, clusters, and nanocrystals. The monoclinic Zintl phases, Na4Si4 and Na4Ge4, contain isolated homo-tetrahedranide [Si4]4− and [Ge4]4− clusters surrounded by alkali metal cations. In this study, a simple scalable route has been applied to prepare Zintl phases of composition Na4Si4 and Na4Ge4 using the reaction between NaH and Si or Ge at low temperature (420 °C for Na4Si4 and 270 °C for Na4Ge4). The method was also applied to K4Ge4, using KH and Ge as raw materials, to show the versatility of this approach. The influence of specific reaction conditions on the purity of these Zintl phases has been studied by controlling five factors: the method of reagent mixing (manual or ball milled), the stoichiometry between raw materials, the reaction temperature, the heating time and the gas flow rate. Moderate ball-milling and excess NaH or KH facilitate the formation of pure Na4Si4, Na4Ge4 or K4Ge4 at 420 °C (Na4Si4) or 270 °C (both M4Ge4 compounds, M = Na, K). TG/DSC analysis of the reaction of NaH and Ge indicates that ball milling reduces the temperature for reaction and confirms the formation temperature. This method provides large quantities of high quality Na4Si4 and Na4Ge4 without the need for specialized laboratory equipment, such as Schlenk lines, niobium/tantalum containers, or an arc welder, thereby expanding the accessibility and chemical utility of these phases by making them more convenient to prepare. This new synthetic method may also be extended to lithium-containing Zintl phases (LiH is commercially available) as well as to alkali metal-tetrel Zintl compounds of other compositions, e.g. K4Ge9. PMID:19921060

  5. NPF MECHANICAL CELL NaK DISPOSAL AND FUME ABATEMENT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rey, G.

    Some of the fuels originally scheduled for processing in the nonproduction fuel (NPF) processing program incorporated sodium or sodium- potassium alloy (NaK) as the bonding material between stainless-steel cladding and the uranium or uranium-molybdenum alloy core. Because of the special hazards involved in handling NaK, studies were made to determine safe methods for processing NaK-containing fuels. An underwater NaK dispensing system was installed, and tests were made to determine the characteristics of the NaK-water reaction. The equipment consisted of a dispenser, reaction pan, and off-gas scrubber. After initinl studies, a prototype test was made wherein U-Mo canned slugs containing NaKmore » reservoirs were hack sawed underwater. The studies demonstrated that the NaK reservoirs can be safely deactivated by hack sawing under a submerged hood in a shallow water bath. (W.L.H.)« less

  6. pH-regulative synthesis of Na 3(VPO 4) 2F 3 nanoflowers and their improved Na cycling stability

    DOE PAGES

    Qi, Yuruo; Mu, Linqin; Zhao, Junmei; ...

    2016-04-08

    Na-ion batteries are becoming increasingly attractive as a low cost energy storage device. Sodium vanadium fluorophosphates have been studied extensively recently due to their high storage capacity and high discharge voltage. Shape and size often have a crucial influence over the properties. The controlling synthesis of nanoparticles with special microstructures is significant, which becomes a challenging issue and has drawn considerable attention. In this study, Na 3(VPO 4) 2F 3 nanoflowers have been synthesized via a pH-regulative low-temperature (120 °C) hydro-thermal route. In particular, it is a green route without any organic compounds involved. The hydro-thermal reaction time for themore » formation of Na 3(VPO 4) 2F 3 nanoflowers has also been investigated. A weak acid environment (pH = 2.60) with the possible presence of hydrogen fluoride molecules is necessary for the formation of the desired nanoflower microstructures. Moreover, compared to the nanoparticles obtained by Na 2HPO 4·12H 2O, the as-synthesized Na 3(VPO 4) 2F 3 nanoflowers showed an excellent Na-storage performance in terms of superior cycle stability, even without any further carbon coating or high-temperature treatment.« less

  7. Cu(In,Ga)Se2 surface treatment with Na and NaF: A combined photoelectron spectroscopy and surface photovoltage study in ultra-high vacuum

    NASA Astrophysics Data System (ADS)

    Parvan, V.; Mizrak, A.; Majumdar, I.; Ümsür, B.; Calvet, W.; Greiner, D.; Kaufmann, C. A.; Dittrich, T.; Avancini, E.; Lauermann, I.

    2018-06-01

    Either metallic Na or NaF were deposited onto Cu(In,Ga)Se2 surfaces and studied by photoelectron spectroscopy and surface photovoltage spectroscopy without breaking the ultra-high vacuum. The deposition of elemental Na at room temperature led to the formation of an intermediate Cu and Ga rich layer at the CIGSe surface, whereas for NaF the composition of the CIGSe surface remained unchanged. A metal like surface induced by an inverted near surface region with a reduced number of defect states was formed after the deposition of Na. Under the chosen experimental conditions, the near surface layer was independent on the amount of Na and stable in time. In contrast, the usage of NaF weakened the inversion and led to an increased band bending compared to the untreated CIGSe sample. The SPV signals decreased with proceeding time after the deposition of NaF.

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

    NASA Technical Reports Server (NTRS)

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

    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 salt evaporates, result in major morphological changes including a loss of columnar structure and a significant increase in porosity. This effect is more pronounced in Na2MoO4/Mo electrodes, due to the lower stability of Na2MoO4.

  9. Functional identification and characterization of sodium binding sites in Na symporters

    PubMed Central

    Loo, Donald D. F.; Jiang, Xuan; Gorraitz, Edurne; Hirayama, Bruce A.; Wright, Ernest M.

    2013-01-01

    Sodium cotransporters from several different gene families belong to the leucine transporter (LeuT) structural family. Although the identification of Na+ in binding sites is beyond the resolution of the structures, two Na+ binding sites (Na1 and Na2) have been proposed in LeuT. Na2 is conserved in the LeuT family but Na1 is not. A biophysical method has been used to measure sodium dissociation constants (Kd) of wild-type and mutant human sodium glucose cotransport (hSGLT1) proteins to identify the Na+ binding sites in hSGLT1. The Na1 site is formed by residues in the sugar binding pocket, and their mutation influences sodium binding to Na1 but not to Na2. For the canonical Na2 site formed by two –OH side chains, S392 and S393, and three backbone carbonyls, mutation of S392 to cysteine increased the sodium Kd by sixfold. This was accompanied by a dramatic reduction in the apparent sugar and phlorizin affinities. We suggest that mutation of S392 in the Na2 site produces a structural rearrangement of the sugar binding pocket to disrupt both the binding of the second Na+ and the binding of sugar. In contrast, the S393 mutations produce no significant changes in sodium, sugar, and phlorizin affinities. We conclude that the Na2 site is conserved in hSGLT1, the side chain of S392 and the backbone carbonyl of S393 are important in the first Na+ binding, and that Na+ binding to Na2 promotes binding to Na1 and also sugar binding. PMID:24191006

  10. Fabrication and Luminescence Characterization of a Silica Nanomatrix Embedded with NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Thangaraju, Dheivasigamani; Santhana, Vedi; Matsuda, Satoshi; Hayakawa, Yasuhiro

    2018-05-01

    Hexagonal NaYF4:Yb:Er:Tm@NaGdF4 core-shell nanocrystals were synthesized using a seed mediated hot injection method, and monodispersed Fe3O4 (4 nm) nanoparticles were prepared from iron(II) actylacetonate by a precursor thermal decomposition method. Structural and morphology verified NaYF4:Yb:Er:Tm@NaGdF4 and Fe3O4 nanoparticles were utilized for the preparation of NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4@SiO2 nanocomposite using a micro-emulsion method. Existence of Fe3O4 in NaYF4:Yb:Er:Tm@NaGdF4 in SiO2 nano-spheres were confirmed with transmission electron microscopy. Luminescence measurement revealed that NaYF4:Yb:Er:Tm@NaGdF4 exhibited strong emissions at green and red regions, in addition to a weak blue emission also observed under 980 nm excitation. Up-conversion emission of the nanoparticle-embedded silica nanocomposite showed that the up-conversion emission was not affected by Fe3O4 nanoparticles.

  11. The para-HK/QK correspondence

    NASA Astrophysics Data System (ADS)

    Dyckmanns, Malte; Vaughan, Owen

    2017-06-01

    We generalise the hyper-Kähler/quaternionic Kähler (HK/QK) correspondence to include para-geometries, and present a new concise proof that the target manifold of the HK/QK correspondence is quaternionic Kähler. As an application, we construct one-parameter deformations of the temporal and Euclidean supergravity c-map metrics and show that they are para-quaternionic Kähler.

  12. Five ab initio potential energy and dipole moment surfaces for hydrated NaCl and NaF. I. Two-body interactions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yimin, E-mail: yimin.wang@emory.edu; Bowman, Joel M., E-mail: jmbowma@emory.edu; Kamarchik, Eugene, E-mail: eugene.kamarchik@gmail.com

    2016-03-21

    We report full-dimensional, ab initio-based potentials and dipole moment surfaces for NaCl, NaF, Na{sup +}H{sub 2}O, F{sup −}H{sub 2}O, and Cl{sup −}H{sub 2}O. The NaCl and NaF potentials are diabatic ones that dissociate to ions. These are obtained using spline fits to CCSD(T)/aug-cc-pV5Z energies. In addition, non-linear least square fits using the Born-Mayer-Huggins potential are presented, providing accurate parameters based strictly on the current ab initio energies. The long-range behavior of the NaCl and NaF potentials is shown to go, as expected, accurately to the point-charge Coulomb interaction. The three ion-H{sub 2}O potentials are permutationally invariant fits to roughly 20 000more » coupled cluster CCSD(T) energies (awCVTZ basis for Na{sup +} and aVTZ basis for Cl{sup −} and F{sup −}), over a large range of distances and H{sub 2}O intramolecular configurations. These potentials are switched accurately in the long range to the analytical ion-dipole interactions, to improve computational efficiency. Dipole moment surfaces are fits to MP2 data; for the ion-ion cases, these are well described in the intermediate- and long-range by the simple point-charge expression. The performance of these new fits is examined by direct comparison to additional ab initio energies and dipole moments along various cuts. Equilibrium structures, harmonic frequencies, and electronic dissociation energies are also reported and compared to direct ab initio results. These indicate the high fidelity of the new PESs.« less

  13. Secretory NaCl and volume flow in renal tubules.

    PubMed

    Beyenbach, K W

    1986-05-01

    This review attempts to give a retrospective survey of the available evidence concerning the secretion of NaCl and fluid in renal tubules of the vertebrate kidney. In the absence of glomerular filtration, epithelial secretory mechanisms, which to this date have not been elucidated, are responsible for the renal excretion of NaCl and water in aglomerular fish. However, proximal tubules isolated from glomerular fish kidneys of the flounder, killifish, and the shark also have the capacity to secrete NaCl and fluid. In shark proximal tubules, fluid secretion appears to be driven via secondary active transport of Cl. In another marine vertebrate, the sea snake, secretion of Na (presumably NaCl) and fluid is observed in freshwater-adapted and water-loaded animals. Proximal tubules of mammals can be made to secrete NaCl in vitro together with secretion of aryl acids. An epithelial cell line derived from dog kidney exhibits secondary active secretion of Cl when stimulated with catecholamines. Tubular secretion of NaCl and fluid may serve a variety of renal functions, all of which are considered here. The occurrence of NaCl and fluid secretion in glomerular proximal tubules of teleosts, elasmobranchs, and reptiles and in mammalian renal tissue cultures suggests that the genetic potential for NaCl secretion is present in every vertebrate kidney.

  14. Low-temperature glasslike properties in (NaCl)1-x(NaCN)x

    NASA Astrophysics Data System (ADS)

    Watson, Susan K.; Pohl, R. O.

    1995-04-01

    Thermal conductivity, internal friction, transverse sound velocity (60 mK to 300 K), and specific-heat data (100 mK to 40 K) for (NaCl)1-x(NaCN)x (x=0, 0.025, 0.05, 0.1, 0.76, 1) show a progression from crystalline to glasslike behavior as the CN- concentration is increased from 0 to 76 %. The evolution of glasslike properties is compared to that in other crystals in which glasslike properties evolve with increasing disorder, e.g., (KBr)1-x(KCN)x and Ba1-xLaxF2-x. For (KBr)1-x(KCN)x, Sethna and Chow have shown that as the concentration of the almost freely rotating CN- ions is increased the average potential barrier for CN- reorientation also increases through elastic quadrupolar interactions. For x~0.5, only a small density of low-energy states is left, which equals that observed in structural glasses. In Ba1-xLaxF2-x, on the other hand, the crystal field for small doping x is so large that no atomic motion occurs at low temperatures. (NaCl)1-x(NaCN)x is shown to represent an intermediate case, in that the crystal field is non-negligible at small x, yet glasslike low-energy excitations indicative of very small potential barrier heights evolve with increasing x. It is argued that random internal strains cause a decrease of the barrier heights in these crystals, which lead to the low-energy excitations. It is proposed that random strains have a similar effect in other disordered crystals as in Ba1-xLaxF2-x, which for small x show no low-energy mobile states, yet which for large x become glasslike.

  15. 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.

  16. Role of alkali carbonate and salt in topochemical synthesis of K1/2Na1/2NbO3 and NaNbO3 templates

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Seok; Jeon, Jae-Ho; Choi, Si-Young

    2013-11-01

    Since the properties of lead-free piezoelectric materials have thus far failed to meet those of lead-based materials, either chemical doping or morphological texturing should be employed to improve the piezoelectric properties of lead-free piezoelectric ceramics. The goal of this study was to synthesize plate-like K1/2Na1/2NbO3 and NaNbO3 particles, which are the most favorable templates for morphological texturing of K1/2Na1/2NbO3 ceramics. To achieve this goal, Bi2.5Na3.5Nb5O18 precursors in a plate-like shape were first synthesized and subsequently converted into K1/2Na1/2NbO3 or NaNbO3 particles that retain the morphology of Bi2.5Na3.5Nb5O18. In this study, we found that sodium or potassium carbonate does not play a major role in converting the Bi2.5Na3.5Nb5O18 precursor to K1/2Na1/2NbO3 or NaNbO3, on the contrary to previous reports; however, the salt contributes to the conversion reaction. All synthesis processes have been performed via a molten salt method, and scanning electron microscopy, scanning probe microscopy, and inductively coupled plasma mass spectroscopy were used to characterize the synthesized K1/2Na1/2NbO3 or NaNbO3 templates.

  17. Natural variability in Drosophila larval and pupal NaCl tolerance.

    PubMed

    Riedl, Craig A L; Oster, Sara; Busto, Macarena; Mackay, Trudy F C; Sokolowski, Marla B

    2016-05-01

    The regulation of NaCl is essential for the maintenance of cellular tonicity and functionality, and excessive salt exposure has many adverse effects. The fruit fly, Drosophila melanogaster, is a good osmoregulator and some strains can survive on media with very low or high NaCl content. Previous analyses of mutant alleles have implicated various stress signaling cascades in NaCl sensitivity or tolerance; however, the genes influencing natural variability of NaCl tolerance remain for the most part unknown. Here, we use two approaches to investigate natural variation in D. melanogaster NaCl tolerance. We describe four D. melanogaster lines that were selected for different degrees of NaCl tolerance, and present data on their survival, development, and pupation position when raised on varying NaCl concentrations. After finding evidence for natural variation in salt tolerance, we present the results of Quantitative Trait Loci (QTL) mapping of natural variation in larval and pupal NaCl tolerance, and identify different genomic regions associated with NaCl tolerance during larval and pupal development. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. A Chimera Na+-Pump Rhodopsin as an Effective Optogenetic Silencer

    PubMed Central

    Hoque, Mohammad Razuanul; Ishizuka, Toru; Inoue, Keiichi; Abe-Yoshizumi, Rei; Igarashi, Hiroyuki; Mishima, Takaaki; Kandori, Hideki

    2016-01-01

    With the progress of optogenetics, the activities of genetically identified neurons can be optically silenced to determine whether the neurons in question are necessary for the network performance of the behavioral expression. This logical induction is expected to be improved by the application of the Na+ pump rhodopsins (NaRs), which hyperpolarize the membrane potential with negligible influence on the ionic/pH balance. Here, we made several chimeric NaRs between two NaRs, KR2 and IaNaR from Krokinobacter eikastus and Indibacter alkaliphilus, respectively. We found that one of these chimeras, named I1K6NaR, exhibited some improvements in the membrane targeting and photocurrent properties over native NaRs. The I1K6NaR-expressing cortical neurons were stably silenced by green light irradiation for a certain long duration. With its rapid kinetics and voltage dependency, the photoactivation of I1K6NaR would specifically counteract the generation of action potentials with less hyperpolarization of the neuronal membrane potential than KR2. PMID:27861619

  19. Co-intercalation of Mg(2+) and Na(+) in Na(0.69)Fe2(CN)6 as a High-Voltage Cathode for Magnesium Batteries.

    PubMed

    Kim, Dong-Min; Kim, Youngjin; Arumugam, Durairaj; Woo, Sang Won; Jo, Yong Nam; Park, Min-Sik; Kim, Young-Jun; Choi, Nam-Soon; Lee, Kyu Tae

    2016-04-06

    Thanks to the advantages of low cost and good safety, magnesium metal batteries get the limelight as substituent for lithium ion batteries. However, the energy density of state-of-the-art magnesium batteries is not high enough because of their low operating potential; thus, it is necessary to improve the energy density by developing new high-voltage cathode materials. In this study, nanosized Berlin green Fe2(CN)6 and Prussian blue Na(0.69)Fe2(CN)6 are compared as high-voltage cathode materials for magnesium batteries. Interestingly, while Mg(2+) ions cannot be intercalated in Fe2(CN)6, Na(0.69)Fe2(CN)6 shows reversible intercalation and deintercalation of Mg(2+) ions, although they have the same crystal structure except for the presence of Na(+) ions. This phenomenon is attributed to the fact that Mg(2+) ions are more stable in Na(+)-containing Na(0.69)Fe2(CN)6 than in Na(+)-free Fe2(CN)6, indicating Na(+) ions in Na(0.69)Fe2(CN)6 plays a crucial role in stabilizing Mg(2+) ions. Na(0.69)Fe2(CN)6 delivers reversible capacity of approximately 70 mA h g(-1) at 3.0 V vs Mg/Mg(2+) and shows stable cycle performance over 35 cycles. Therefore, Prussian blue analogues are promising structures for high-voltage cathode materials in Mg batteries. Furthermore, this co-intercalation effect suggests new avenues for the development of cathode materials in hybrid magnesium batteries that use both Mg(2+) and Na(+) ions as charge carriers.

  20. Crystallization kinetics from mixture Na2SO4/glycerol droplets of Na2SO4 by FTIR-ATR

    NASA Astrophysics Data System (ADS)

    Tan, Dan-Ting; Cai, Chen; Zhang, Yun; Wang, Na; Pang, Shu-Feng; Zhang, Yun-Hong

    2016-08-01

    The efflorescence of mixed Na2SO4/glycerol aerosols on the ZnSe substrate with various mole ratios (Na2SO4/glycerol = 1:1, 1:2, 1:4) has been studied in the relative humidity (RH) linearly decline process, using a situ Fourier transform infrared attenuated total reflection (FTIR-ATR) technique. The crystal ratio at a given RH can be gained by the absorbance of the band at 1132 cm-1, which shows the incomplete nucleation for mixed Na2SO4/glycerol aerosols and the decreased amount of the droplets crystallized at the lowest RH with the glycerol increase. Using the volume fraction of droplets that have yet to crystallize, the heterogeneous nucleation kinetics has been gained. By the Extended Aerosol Inorganics Model (E-AIM), the nucleation rate as the function of solute saturation degree has been gained for various mixed Na2SO4/glycerol aerosols.

  1. Experimental study of the astrophysically important Na 23 ( α , p ) Mg 26 and Na 23 ( α , n ) Al 26 reactions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.

    The 23Na(α,p) 26Mg and 23Na(α,n) 26Al reactions are important for our understanding of the 26Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α,p) 26Mg and the 23Na(α,n) 26Al reactions are in good agreementmore » with previous experiments and with statistical-model calculations. As a result, the astrophysical reaction rate of the 23Na(α,n) 26Al reaction has been reevaluated and it was found to be larger than the recommended rate.« less

  2. Experimental study of the astrophysically important Na 23 ( α , p ) Mg 26 and Na 23 ( α , n ) Al 26 reactions

    DOE PAGES

    Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; ...

    2016-12-19

    The 23Na(α,p) 26Mg and 23Na(α,n) 26Al reactions are important for our understanding of the 26Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α,p) 26Mg and the 23Na(α,n) 26Al reactions are in good agreementmore » with previous experiments and with statistical-model calculations. As a result, the astrophysical reaction rate of the 23Na(α,n) 26Al reaction has been reevaluated and it was found to be larger than the recommended rate.« less

  3. Double Knockout of the Na+-Driven Cl−/HCO3− Exchanger and Na+/Cl− Cotransporter Induces Hypokalemia and Volume Depletion

    PubMed Central

    Sinning, Anne; Radionov, Nikita; Trepiccione, Francesco; López-Cayuqueo, Karen I.; Jayat, Maximilien; Baron, Stéphanie; Cornière, Nicolas; Alexander, R. Todd; Hadchouel, Juliette; Eladari, Dominique; Hübner, Christian A.

    2017-01-01

    We recently described a novel thiazide–sensitive electroneutral NaCl transport mechanism resulting from the parallel operation of the Cl−/HCO3− exchanger pendrin and the Na+–driven Cl−/2HCO3− exchanger (NDCBE) in β-intercalated cells of the collecting duct. Although a role for pendrin in maintaining Na+ balance, intravascular volume, and BP is well supported, there is no in vivo evidence for the role of NDCBE in maintaining Na+ balance. Here, we show that deletion of NDCBE in mice caused only subtle perturbations of Na+ homeostasis and provide evidence that the Na+/Cl− cotransporter (NCC) compensated for the inactivation of NDCBE. To unmask the role of NDCBE, we generated Ndcbe/Ncc double–knockout (dKO) mice. On a normal salt diet, dKO and single-knockout mice exhibited similar activation of the renin-angiotensin-aldosterone system, whereas only dKO mice displayed a lower blood K+ concentration. Furthermore, dKO mice displayed upregulation of the epithelial sodium channel (ENaC) and the Ca2+–activated K+ channel BKCa. During NaCl depletion, only dKO mice developed marked intravascular volume contraction, despite dramatically increased renin activity. Notably, the increase in aldosterone levels expected on NaCl depletion was attenuated in dKO mice, and single-knockout and dKO mice had similar blood K+ concentrations under this condition. In conclusion, NDCBE is necessary for maintaining sodium balance and intravascular volume during salt depletion or NCC inactivation in mice. Furthermore, NDCBE has an important role in the prevention of hypokalemia. Because NCC and NDCBE are both thiazide targets, the combined inhibition of NCC and the NDCBE/pendrin system may explain thiazide-induced hypokalemia in some patients. PMID:27151921

  4. Oxidation of ethanol on NaX zeolite modified with transition metals

    NASA Astrophysics Data System (ADS)

    Mirzai, J. I.; Nadirov, P. A.; Velieva, A. D.; Muradkhanli, V. G.

    2017-06-01

    NaLaX, NaX + Co, and NaPdX catalysts are synthesized by modification of NaX zeolite with transition metals (La, Co, Pd). The activity of the prepared materials in catalytic ethanol oxidation is studied in the temperature range of 423-723 K. It is shown that NaPdX and NaX + Co accelerate the reactions of partial and complete oxidation of ethanol as the temperature rises. NaLaX accelerates both intramolecular and intermolecular dehydration of alcohol. It is shown that the NaPdX (1.0% Pd) sample has the highest activity in the complete oxidation of alcohol with the formation of CO2.

  5. Characterization of ZnAl cast alloys with Na addition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gancarz, Tomasz, E-mail: t.gancarz@imim.pl; Cempura, Grzegorz; Skuza, Wojciech

    2016-01-15

    This study was aimed at evaluating the microstructural change and thermal, electrical and mechanical properties with the addition of Na to eutectic ZnAl alloys. Solders based on eutectic ZnAl containing 0.2 to 3.0 (wt.%) of Na were developed for high temperature solder. Differential scanning calorimetry (DSC) measurements were performed to determine the melting temperatures of the alloys. Thermal linear expansion and electrical resistivity measurements were performed over − 50 °C to 300 °C and 30 °C to 300 °C temperature ranges, respectively. The microstructure of the specimens was analyzed using scanning (SEM) and transmission electron microscopy (TEM) techniques. Chemical microanalysismore » was performed by energy-dispersive X-ray spectroscopy (EDS) on SEM and TEM. The precipitates of NaZn{sub 13} were confirmed by X-ray diffraction (XRD) measurements and selected area electron diffraction (SAED) techniques. The addition of Na to eutectic ZnAl alloy increased the electrical resistivity and reduced the coefficient of thermal expansion; however, the melting point did not change. The mechanical properties, strain and microhardness increased with Na content in alloys. - Highlights: • High temperature soldering materials of ZnAl with Na were designed and characterized. • Precipitates of NaZn{sub 13}were observed and confirmed using TEM and XRD. • Addition of Na to eutectic ZnAl cussed increased mechanical properties. • NaZn{sub 13} caused increased electrical resistivity and microhardness, and reduced the CTE.« less

  6. Measurements of the liquidus surface and solidus transitions of the NaCl-UCl3 and NaCl-UCl3-CeCl3 phase diagrams

    NASA Astrophysics Data System (ADS)

    Sooby, E. S.; Nelson, A. T.; White, J. T.; McIntyre, P. M.

    2015-11-01

    NaCl-UCl3-PuCl3 is proposed as the fuel salt for a number of molten salt reactor concepts. No experimental data exists for the ternary system, and limited data is available for the binary compositions of this salt system. Differential scanning calorimetry is used in this study to examine the liquidus surface and solidus transition of a surrogate fuel-salt (NaCl-UCl3-CeCl3) and to reinvestigate the NaCl-UCl3 eutectic phase diagram. The results of this study show good agreement with previously reported data for the pure salt compounds used (NaCl, UCl3, and CeCl3) as well as for the eutectic points for the NaCl-UCl3 and NaCl-CeCl3 binary systems. The NaCl-UCl3 liquidus surface produced in this study predicts a 30-40 °C increase on the NaCl-rich side of the binary phase diagram. The increase in liquidus temperature could prove significant to molten salt reactor modeling.

  7. Kinetin Reversal of NaCl Effects

    PubMed Central

    Katz, Adriana; Dehan, Klara; Itai, Chanan

    1978-01-01

    Leaf discs of Nicotiana rustica L. were floated on NaCl in the presence of kinetin or abscisic acid. On the 5th day 14CO2 fixation, [3H]leucine incorporation, stomatal conductance, and chlorophyll content were determined. Kinetin either partially or completely reversed the inhibitory effects of NaCl while ABA had no effect. PMID:16660618

  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. Magnetism in Na-filled Fe-based skutterudites

    DOE PAGES

    Xing, Guangzong; Fan, Xiaofeng; Zheng, Weitao; ...

    2015-06-01

    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. We investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe 4Sb 12 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 amore » material near an itinerant ferromagnetic quantum critical point. NaFe 4P 12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe 4Sb 12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe 4As 12 shows intermediate behavior. We also present results for skutterudite FeSb 3, which is a metastable phase that has been reported in thin film form.« less

  10. The effect of NaCl 0.9% and NaCl 0.45% on sodium, chloride, and acid-base balance in a PICU population.

    PubMed

    Almeida, Helena Isabel; Mascarenhas, Maria Inês; Loureiro, Helena Cristina; Abadesso, Clara S; Nunes, Pedro S; Moniz, Marta S; Machado, Maria Céu

    2015-01-01

    To study the effect of two intravenous maintenance fluids on plasma sodium (Na), and acid-base balance in pediatric intensive care patients during the first 24h of hospitalization. A prospective randomized controlled study was performed, which allocated 233 patients to groups: (A) NaCl 0.9% or (B) NaCl 0.45%. Patients were aged 1 day to 18 years, had normal electrolyte concentrations, and suffered an acute insult (medical/surgical). change in plasma sodium. Parametric tests: t-tests, ANOVA, X(2) statistical significance level was set at α=0.05. Group A (n=130): serum Na increased by 2.91 (±3.9)mmol/L at 24h (p<0.01); 2% patients had Na higher than 150 mmol/L. Mean urinary Na: 106.6 (±56.8)mmol/L. No change in pH at 0 and 24h. Group B (n=103): serum Na did not display statistically significant changes. Fifteen percent of the patients had Na<135 mmol/L at 24h. The two fluids had different effects on respiratory and post-operative situations. The use of saline 0.9% was associated with a lower incidence of electrolyte disturbances. Copyright © 2015 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  11. ATP Dependence of Na+/H+ Exchange

    PubMed Central

    Demaurex, Nicolas; Romanek, Robert R.; Orlowski, John; Grinstein, Sergio

    1997-01-01

    We studied the ATP dependence of NHE-1, the ubiquitous isoform of the Na+/H+ antiporter, using the whole-cell configuration of the patch-clamp technique to apply nucleotides intracellularly while measuring cytosolic pH (pHi) by microfluorimetry. Na+/H+ exchange activity was measured as the Na+-driven pHi recovery from an acid load, which was imposed via the patch pipette. In Chinese hamster ovary (CHO) fibroblasts stably transfected with NHE-1, omission of ATP from the pipette solution inhibited Na+/H+ exchange. Conversely, ATP perfusion restored exchange activity in cells that had been metabolically depleted by 2-deoxy-d-glucose and oligomycin. In cells dialyzed in the presence of ATP, no “run-down” was observed even after extended periods, suggesting that the nucleotide is the only diffusible factor required for optimal NHE-1 activity. Half-maximal activation of the antiporter was obtained at ∼5 mM Mg-ATP. Submillimolar concentrations failed to sustain Na+/H+ exchange even when an ATP regenerating system was included in the pipette solution. High ATP concentrations are also known to be required for the optimal function of other cation exchangers. In the case of the Na/Ca2+ exchanger, this requirement has been attributed to an aminophospholipid translocase, or “flippase.” The involvement of this enzyme in Na+/H+ exchange was examined using fluorescent phosphatidylserine, which is actively translocated by the flippase. ATP depletion decreased the transmembrane uptake of NBD-labeled phosphatidylserine (NBD-PS), indicating that the flippase was inhibited. Diamide, an agent reported to block the flippase, was as potent as ATP depletion in reducing NBD-PS uptake. However, diamide had no effect on Na+/H+ exchange, implying that the effect of ATP is not mediated by changes in lipid distribution across the plasma membrane. K-ATP and ATPγS were as efficient as Mg-ATP in sustaining NHE-1 activity, while AMP-PNP and AMP-PCP only partially substituted for ATP. In

  12. Na+ Interactions with the Neutral Amino Acid Transporter ASCT1*

    PubMed Central

    Scopelliti, Amanda J.; Heinzelmann, Germano; Kuyucak, Serdar; Ryan, Renae M.; Vandenberg, Robert J.

    2014-01-01

    The alanine, serine, cysteine transporters (ASCTs) belong to the solute carrier family 1A (SLC1A), which also includes the excitatory amino acid transporters (EAATs) and the prokaryotic aspartate transporter GltPh. Acidic amino acid transport by the EAATs is coupled to the co-transport of three Na+ ions and one proton, and the counter-transport of one K+ ion. In contrast, neutral amino acid exchange by the ASCTs does not require protons or the counter-transport of K+ ions and the number of Na+ ions required is not well established. One property common to SLC1A family members is a substrate-activated anion conductance. We have investigated the number and location of Na+ ions required by ASCT1 by mutating residues in ASCT1 that correspond to residues in the EAATs and GltPh that are involved in Na+ binding. Mutations to all three proposed Na+ sites influence the binding of substrate and/or Na+, or the rate of substrate exchange. A G422S mutation near the Na2 site reduced Na+ affinity, without affecting the rate of exchange. D467T and D467A mutations in the Na1 site reduce Na+ and substrate affinity and also the rate of substrate exchange. T124A and D380A mutations in the Na3 site selectively reduce the affinity for Na+ and the rate of substrate exchange without affecting substrate affinity. In many of the mutants that reduce the rate of substrate transport the amplitudes of the substrate-activated anion conductances are not substantially affected indicating altered ion dependence for channel activation compared with substrate exchange. PMID:24808181

  13. Neuronal Na+ Channels Are Integral Components of Pro-arrhythmic Na+/Ca2+ Signaling Nanodomain That Promotes Cardiac Arrhythmias During β-adrenergic Stimulation

    PubMed Central

    Radwański, Przemysław B.; Ho, Hsiang-Ting; Veeraraghavan, Rengasayee; Brunello, Lucia; Liu, Bin; Belevych, Andriy E.; Unudurthi, Sathya D.; Makara, Michael A.; Priori, Silvia G.; Volpe, Pompeo; Armoundas, Antonis A.; Dillmann, Wolfgang H.; Knollmann, Bjorn C.; Mohler, Peter J.; Hund, Thomas J.; Györke, Sándor

    2016-01-01

    Background Cardiac arrhythmias are a leading cause of death in the US. Vast majority of these arrhythmias including catecholaminergic polymorphic ventricular tachycardia (CPVT) are associated with increased levels of circulating catecholamines and involve abnormal impulse formation secondary to aberrant Ca2+ and Na+ handling. However, the mechanistic link between β-AR stimulation and the subcellular/molecular arrhythmogenic trigger(s) remains elusive. Methods and Results We performed functional and structural studies to assess Ca2+ and Na+ signaling in ventricular myocyte as well as surface electrocardiograms in mouse models of cardiac calsequestrin (CASQ2)-associated CPVT. We demonstrate that a subpopulation of Na+ channels (neuronal Na+ channels; nNav) that colocalize with RyR2 and Na+/Ca2+ exchanger (NCX) are a part of the β-AR-mediated arrhythmogenic process. Specifically, augmented Na+ entry via nNav in the settings of genetic defects within the RyR2 complex and enhanced sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA)-mediated SR Ca2+ refill is both an essential and a necessary factor for the arrhythmogenesis. Furthermore, we show that augmentation of Na+ entry involves β-AR-mediated activation of CAMKII subsequently leading to nNav augmentation. Importantly, selective pharmacological inhibition as well as silencing of Nav1.6 inhibit myocyte arrhythmic potential and prevent arrhythmias in vivo. Conclusion These data suggest that the arrhythmogenic alteration in Na+/Ca2+ handling evidenced ruing β-AR stimulation results, at least in part, from enhanced Na+ influx through nNav. Therefore, selective inhibition of these channels and Nav1.6 in particular can serve as a potential antiarrhythmic therapy. PMID:27747307

  14. Feasibility study for a secondary Na/S battery

    NASA Technical Reports Server (NTRS)

    Abraham, K. M.; Schiff, R.; Brummer, S. B.

    1979-01-01

    The feasibility of a moderate temperature Na battery was studied. This battery is to operate at a temperature in the range of 100-150 C. Two kinds of cathode were investigated: (1) a soluble S cathode consisting of a solution of Na2Sn in an organic solvent and (2) an insoluble S cathode consisting of a transition metal dichalcogenide in contact with a Na(+)ion conducting electrolyte. Four amide solvents, dimethyl acetamide, diethyl acetamide, N-methyl acetamide and acetamide, were investigated as possible solvents for the soluble S cathode. Results of stability and electrochemical studies using these solvents are presented. The dialkyl substituted amides were found to be superior. Although the alcohol 1,3-cyclohexanediol was found to be stable in the presence of Na2Sn at 130 C, its Na2Sn solutions did not appear to have suitable electrochemical properties.

  15. Los plaguicidas y la contaminacion del medio ambiente Venezolano

    USGS Publications Warehouse

    Stickel, L.F.; Stickel, W.H.

    1972-01-01

    RESUMEN DE RECOMENDACIONES Recomendaciones para el Programa de Investigacion: 1. Establecer un sistema de muestreo biologico para detectar los niveles tendencias de los productos quimicos toxicos en un peque?o numero de si tios representativos. 2. Mantener continua vigilancia de la contaminacion ambiental, mediante la seleccion acertadamente dirigida de las zonas afectadas y de las fuentes de contaminacion. 3. Realizar estudios acerca de las poblaciones de animales silvestres, y del exito de los procesos reproductivos de las especies o grupos clayes de animales que se consideran mas gravemente afectados. 4. Preparar recomendaciones para una accion gubernamental de proteccion al hombre, a la fauna silvestre y al medio ambiente. Recomendaciones para la Accion Administrativa: 1. Establecer limites a la tolerancia de los residuos de plaguicidas en los alimentos. Constituye una medida clave para disminuir la contaminacion ambiental. 2. Establecer normas de calidad del agua para las corrientes, represas, la gos y otros cuerpos. Es la segunda medida clave para reducir la contaminacion del ambiente 3. Exigir un tratamiento adecuado de los efluentes industriales, especialmente antes de que se construyan las nuevas plantas. 4. Exigir a los agricultores que en el uso de plaguicidas sigan los consejos tecnicos autorizados y negar a los vendedores el derecho a recomendar productos por su cuenta. 5. Tomar medidas para recoger y eliminar los recipientes y sobrantes de los plaguicidas.

  16. Mechanistic origin of low polarization in aprotic Na-O2 batteries.

    PubMed

    Ma, Shunchao; McKee, William C; Wang, Jiawei; Guo, Limin; Jansen, Martin; Xu, Ye; Peng, Zhangquan

    2017-05-21

    Research interest in aprotic sodium-air (Na-O 2 ) batteries is growing because of their considerably high theoretical specific energy and potentially better reversibility than lithium-air (Li-O 2 ) batteries. While Li 2 O 2 has been unequivocally identified as the major discharge product in Li-O 2 batteries containing relatively stable electrolytes, a multitude of discharge products, including NaO 2 , Na 2 O 2 and Na 2 O 2 ·2H 2 O, have been reported for Na-O 2 batteries and the corresponding cathodic electrochemistry remains incompletely understood. Herein, we provide molecular-level insights into the key mechanistic differences between Na-O 2 and Li-O 2 batteries based on gold electrodes in strictly dry, aprotic dimethyl sulfoxide electrolytes through a combination of in situ spectroelectrochemistry and density functional theory based modeling. While like Li-O 2 batteries, the formation of oxygen reduction products (i.e., O 2 - , NaO 2 and Na 2 O 2 ) in Na-O 2 batteries depends critically on the electrode potential, two factors lead to a better reversibility of Na-O 2 electrochemistry, and are therefore highly beneficial to a viable rechargeable metal-air battery design: (i) only O 2 - and NaO 2 , and no Na 2 O 2 , form down to as low as ∼1.5 V vs. Na/Na + during discharge; (ii) solid NaO 2 is quite soluble and its formation and oxidation can proceed through micro-reversible EC (a chemical reaction of the product after the electron transfer) and CE (a chemical reaction preceding the electron transfer) processes, respectively, with O 2 - as the key intermediate.

  17. Mutations in the Na+/Citrate Cotransporter NaCT (SLC13A5) in Pediatric Patients with Epilepsy and Developmental Delay

    PubMed Central

    Klotz, Jenna; Porter, Brenda E; Colas, Claire; Schlessinger, Avner; Pajor, Ana M

    2016-01-01

    Mutations in the SLC13A5 gene that codes for the Na+/citrate cotransporter, NaCT, are associated with early onset epilepsy, developmental delay and tooth dysplasia in children. In this study, we identify additional SLC13A5 mutations in nine epilepsy patients from six families. To better characterize the syndrome, families with affected children answered questions about the scope of illness and the treatment strategies. Currently, there are no effective treatments, but some antiepileptic drugs targeting the γ-aminobutyric acid system reduce seizure frequency. Acetazolamide, a carbonic anhydrase inhibitor and atypical antiseizure medication, decreases seizures in four patients. In contrast to previous reports, the ketogenic diet and fasting resulted in worsening of symptoms. The effects of the mutations on NaCT transport function and protein expression were examined by transient transfections of COS-7 cells. There was no transport activity from any of the mutant transporters, although some of the mutant transporter proteins were present on the plasma membrane. The structural model of NaCT suggests that these mutations can affect helix packing or substrate binding. We tested various treatments, including chemical chaperones and low temperatures, but none improved transport function in the NaCT mutants. Interestingly, coexpression of NaCT and the mutants results in decreased protein expression and activity of the wild-type transporter, indicating functional interaction. In conclusion, this study has identified additional SLC13A5 mutations in patients with chronic epilepsy starting in the neonatal period, with the mutations producing inactive Na+/citrate transporters. PMID:27261973

  18. Hydrogen Sulfide Induced Disruption of Na+ Homeostasis in the Cortex

    PubMed Central

    Chao, Dongman; He, Xiaozhou; Yang, Yilin; Balboni, Gianfranco; Salvadori, Severo; Kim, Dong H.; Xia, Ying

    2012-01-01

    Maintenance of ionic balance is essential for neuronal functioning. Hydrogen sulfide (H2S), a known toxic environmental gaseous pollutant, has been recently recognized as a gasotransmitter involved in numerous biological processes and is believed to play an important role in the neural activities under both physiological and pathological conditions. However, it is unclear if it plays any role in maintenance of ionic homeostasis in the brain under physiological/pathophysiological conditions. Here, we report by directly measuring Na+ activity using Na+ selective electrodes in mouse cortical slices that H2S donor sodium hydrosulfide (NaHS) increased Na+ influx in a concentration-dependent manner. This effect could be partially blocked by either Na+ channel blocker or N-methyl-D-aspartate receptor (NMDAR) blocker alone or almost completely abolished by coapplication of both blockers but not by non-NMDAR blocker. These data suggest that increased H2S in pathophysiological conditions, e.g., hypoxia/ischemia, potentially causes a disruption of ionic homeostasis by massive Na+ influx through Na+ channels and NMDARs, thus injuring neural functions. Activation of delta-opioid receptors (DOR), which reduces Na+ currents/influx in normoxia, had no effect on H2S-induced Na+ influx, suggesting that H2S-induced disruption of Na+ homeostasis is resistant to DOR regulation and may play a major role in neuronal injury in pathophysiological conditions, e.g., hypoxia/ischemia. PMID:22474073

  19. Differential migratory properties of monocytes isolated from human subjects naïve and non-naïve to Cannabis

    PubMed Central

    Silvestroni, Aurelio; Möller, Thomas; Stella, Nephi

    2015-01-01

    This study evaluates the migratory potential of monocytes isolated from two groups of human subjects: naïve and non-naïve to Cannabis. Phytocannabinoids (pCB), the bioactive agents produced by the plant Cannabis, regulate the phenotype and function of immune cells by interacting with CB1 and CB2 receptors. It has been shown that agents influencing the phenotype of circulating monocytes influence the phenotype of macrophages and the outcome of immune responses. To date, nothing is known about the acute and long-term effects of pCB on human circulating monocytes. Healthy subjects were recruited for a single blood draw. Monocytes were isolated, fluorescently labeled and their migration quantified using a validated assay that employs near infrared fluorescence and modified Boyden chambers. CB1 and CB2 receptor mRNA expression was quantified by qPCR. Monocytes from all subjects (n = 10) responded to chemokine (c–c motif) ligand 2 (CCL2) and human serum stimuli. Acute application of pCB significantly inhibited both the basal and CCL2-stimulated migration of monocytes, but only in subjects non-naïve to Cannabis. qPCR analysis indicates that monocytes from subjects non-naïve to Cannabis express significantly more CB1 mRNA. The phenotype of monocytes isolated from subjects non-naïve to Cannabis is significantly different from monocytes isolated from subjects naïve to Cannabis. Only monocytes from subjects non-naïve to Cannabis respond to acute exposure to pCB by reducing their overall migratory capacity. Our study suggests that chronic exposure to Cannabis affects the phenotype of circulating monocytes and accordingly could influence outcome of inflammatory responses occurring in injured tissues. PMID:22492174

  20. Differential migratory properties of monocytes isolated from human subjects naïve and non-naïve to Cannabis.

    PubMed

    Sexton, Michelle; Silvestroni, Aurelio; Möller, Thomas; Stella, Nephi

    2013-06-01

    This study evaluates the migratory potential of monocytes isolated from two groups of human subjects: naïve and non-naïve to Cannabis. Phytocannabinoids (pCB), the bioactive agents produced by the plant Cannabis, regulate the phenotype and function of immune cells by interacting with CB1 and CB2 receptors. It has been shown that agents influencing the phenotype of circulating monocytes influence the phenotype of macrophages and the outcome of immune responses. To date, nothing is known about the acute and long-term effects of pCB on human circulating monocytes. Healthy subjects were recruited for a single blood draw. Monocytes were isolated, fluorescently labeled and their migration quantified using a validated assay that employs near infrared fluorescence and modified Boyden chambers. CB1 and CB2 receptor mRNA expression was quantified by qPCR. Monocytes from all subjects (n = 10) responded to chemokine (c-c motif) ligand 2 (CCL2) and human serum stimuli. Acute application of pCB significantly inhibited both the basal and CCL2-stimulated migration of monocytes, but only in subjects non-naïve to Cannabis. qPCR analysis indicates that monocytes from subjects non-naïve to Cannabis express significantly more CB1 mRNA. The phenotype of monocytes isolated from subjects non-naïve to Cannabis is significantly different from monocytes isolated from subjects naïve to Cannabis. Only monocytes from subjects non-naïve to Cannabis respond to acute exposure to pCB by reducing their overall migratory capacity. Our study suggests that chronic exposure to Cannabis affects the phenotype of circulating monocytes and accordingly could influence outcome of inflammatory responses occurring in injured tissues.

  1. Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

    PubMed Central

    Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

    1979-01-01

    Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent

  2. Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

    PubMed

    Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

    1979-07-01

    Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent

  3. Na+/H+ Exchange Activity in the Plasma Membrane of Arabidopsis1

    PubMed Central

    Qiu, Quan-Sheng; Barkla, Bronwyn J.; Vera-Estrella, Rosario; Zhu, Jian-Kang; Schumaker, Karen S.

    2003-01-01

    In plants, Na+/H+ exchangers in the plasma membrane are critical for growth in high levels of salt, removing toxic Na+ from the cytoplasm by transport out of the cell. The molecular identity of a plasma membrane Na+/H+ exchanger in Arabidopsis (SOS1) has recently been determined. In this study, immunological analysis provided evidence that SOS1 localizes to the plasma membrane of leaves and roots. To characterize the transport activity of this protein, purified plasma membrane vesicles were isolated from leaves of Arabidopsis. Na+/H+ exchange activity, monitored as the ability of Na to dissipate an established pH gradient, was absent in plants grown without salt. However, exchange activity was induced when plants were grown in 250 mm NaCl and increased with prolonged salt exposure up to 8 d. H+-coupled exchange was specific for Na, because chloride salts of other monovalent cations did not dissipate the pH gradient. Na+/H+ exchange activity was dependent on Na (substrate) concentration, and kinetic analysis indicated that the affinity (apparent Km) of the transporter for Na+ is 22.8 mm. Data from two experimental approaches supports electroneutral exchange (one Na+ exchanged for one proton): (a) no change in membrane potential was measured during the exchange reaction, and (b) Na+/H+ exchange was unaffected by the presence or absence of a membrane potential. Results from this research provide a framework for future studies into the regulation of the plant plasma membrane Na+/H+ exchanger and its relative contribution to the maintenance of cellular Na+ homeostasis during plant growth in salt. PMID:12805632

  4. Electron scattering in graphene with adsorbed NaCl nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Drabińska, Aneta, E-mail: Aneta.Drabinska@fuw.edu.pl; Kaźmierczak, Piotr; Bożek, Rafał

    2015-01-07

    In this work, the results of contactless magnetoconductance and Raman spectroscopy measurements performed for a graphene sample after its immersion in NaCl solution were presented. The properties of the immersed sample were compared with those of a non-immersed reference sample. Atomic force microscopy and electron spin resonance experiments confirmed the deposition of NaCl nanoparticles on the graphene surface. A weak localization signal observed using contactless magnetoconductance showed the reduction of the coherence length after NaCl treatment of graphene. Temperature dependence of the coherence length indicated a change from ballistic to diffusive regime in electron transport after NaCl treatment. The mainmore » inelastic scattering process was of the electron-electron type but the major reason for the reduction of the coherence length at low temperatures was additional, temperature independent, inelastic scattering. We associate it with spin flip scattering, caused by NaCl nanoparticles present on the graphene surface. Raman spectroscopy showed an increase in the D and D′ bands intensities for graphene after its immersion in NaCl solution. An analysis of the D, D′, and G bands intensities proved that this additional scattering is related to the decoration of vacancies and grain boundaries with NaCl nanoparticles, as well as generation of new on-site defects as a result of the decoration of the graphene surface with NaCl nanoparticles. The observed energy shifts of 2D and G bands indicated that NaCl deposition on the graphene surface did not change carrier concentration, but reduced compressive biaxial strain in the graphene layer.« less

  5. Arrestins and Spinophilin Competitively Regulate Na+,K+-ATPase Trafficking through Association with a Large Cytoplasmic Loop of the Na+,K+-ATPase

    PubMed Central

    Kimura, Tohru; Allen, Patrick B.; Nairn, Angus C.

    2007-01-01

    The activity and trafficking of the Na+,K+-ATPase are regulated by several hormones, including dopamine, vasopressin, and adrenergic hormones through the action of G-protein–coupled receptors (GPCRs). Arrestins, GPCR kinases (GRKs), 14-3-3 proteins, and spinophilin interact with GPCRs and modulate the duration and magnitude of receptor signaling. We have found that arrestin 2 and 3, GRK 2 and 3, 14-3-3 ε, and spinophilin directly associate with the Na+,K+-ATPase and that the associations with arrestins, GRKs, or 14-3-3 ε are blocked in the presence of spinophilin. In COS cells that overexpressed arrestin, the Na+,K+-ATPase was redistributed to intracellular compartments. This effect was not seen in mock-transfected cells or in cells expressing spinophilin. Furthermore, expression of spinophilin appeared to slow, whereas overexpression of β-arrestins accelerated internalization of the Na+,K+-ATPase endocytosis. We also find that GRKs phosphorylate the Na+,K+-ATPase in vitro on its large cytoplasmic loop. Taken together, it appears that association with arrestins, GRKs, 14-3-3 ε, and spinophilin may be important modulators of Na+,K+-ATPase trafficking. PMID:17804821

  6. Sodium ion transport mechanisms in antiperovskite electrolytes Na 3OBr and Na 4OI 2: An in Situ neutron diffraction study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhu, Jinlong; Wang, Yonggang; Li, Shuai

    Na-rich antiperovskites are recently developed solid electrolytes with enhanced sodium ionic conductivity and show promising functionality as a novel solid electrolyte in an all solid-stat battery. In this work, the sodium ionic transport pathways of the parent compound Na 3OBr, as well as the modified layered antiperovskite Na 4OI 2, were studied and compared through temperature dependent neutron diffraction combined with the maximum entropy method. In the cubic Na 3OBr antiperovskite, the nuclear density distribution maps at 500 K indicate that sodium ions ho within and among oxygen octahedra, and Br - ions are not involved in the tetragonal Namore » 4OI 2 antiperovskite, Na ions, which connect octahedra in the ab plane, have the lowest activation energy barrier. In conclusion, the transport of sodium ions along the c axis is assisted by I - ions.« less

  7. Sodium ion transport mechanisms in antiperovskite electrolytes Na 3OBr and Na 4OI 2: An in Situ neutron diffraction study

    DOE PAGES

    Zhu, Jinlong; Wang, Yonggang; Li, Shuai; ...

    2016-06-02

    Na-rich antiperovskites are recently developed solid electrolytes with enhanced sodium ionic conductivity and show promising functionality as a novel solid electrolyte in an all solid-stat battery. In this work, the sodium ionic transport pathways of the parent compound Na 3OBr, as well as the modified layered antiperovskite Na 4OI 2, were studied and compared through temperature dependent neutron diffraction combined with the maximum entropy method. In the cubic Na 3OBr antiperovskite, the nuclear density distribution maps at 500 K indicate that sodium ions ho within and among oxygen octahedra, and Br - ions are not involved in the tetragonal Namore » 4OI 2 antiperovskite, Na ions, which connect octahedra in the ab plane, have the lowest activation energy barrier. In conclusion, the transport of sodium ions along the c axis is assisted by I - ions.« less

  8. Design and implementation of the NaI(Tl)/CsI(Na) detectors output signal generator

    NASA Astrophysics Data System (ADS)

    Zhou, Xu; Liu, Cong-Zhan; Zhao, Jian-Ling; Zhang, Fei; Zhang, Yi-Fei; Li, Zheng-Wei; Zhang, Shuo; Li, Xu-Fang; Lu, Xue-Feng; Xu, Zhen-Ling; Lu, Fang-Jun

    2014-02-01

    We designed and implemented a signal generator that can simulate the output of the NaI(Tl)/CsI(Na) detectors' pre-amplifier onboard the Hard X-ray Modulation Telescope (HXMT). Using the development of the FPGA (Field Programmable Gate Array) with VHDL language and adding a random constituent, we have finally produced the double exponential random pulse signal generator. The statistical distribution of the signal amplitude is programmable. The occurrence time intervals of the adjacent signals contain negative exponential distribution statistically.

  9. Separating para and ortho water.

    PubMed

    Horke, Daniel A; Chang, Yuan-Pin; Długołęcki, Karol; Küpper, Jochen

    2014-10-27

    Water exists as two nuclear-spin isomers, para and ortho, determined by the overall spin of its two hydrogen nuclei. For isolated water molecules, the conversion between these isomers is forbidden and they act as different molecular species. Yet, these species are not readily separated, and no pure para sample has been produced. Accordingly, little is known about their specific physical and chemical properties, conversion mechanisms, or interactions. The production of isolated samples of both spin isomers is demonstrated in pure beams of para and ortho water in their respective absolute ground state. These single-quantum-state samples are ideal targets for unraveling spin-conversion mechanisms, for precision spectroscopy and fundamental symmetry-breaking studies, and for spin-enhanced applications, for example laboratory astrophysics and astrochemistry or hypersensitized NMR experiments. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Enhancing Catalyzed Decomposition of Na2CO3 with Co2MnO x Nanowire-Decorated Carbon Fibers for Advanced Na-CO2 Batteries.

    PubMed

    Fang, Cong; Luo, Jianmin; Jin, Chengbin; Yuan, Huadong; Sheng, Ouwei; Huang, Hui; Gan, Yongping; Xia, Yang; Liang, Chu; Zhang, Jun; Zhang, Wenkui; Tao, Xinyong

    2018-05-23

    The metal-CO 2 batteries, especially Na-CO 2 , batteries come into sight owing to their high energy density, ability for CO 2 capture, and the abundance of sodium resource. Besides the sluggish electrochemical reactions at the gas cathodes and the instability of the electrolyte at a high voltage, the final discharge product Na 2 CO 3 is a solid and poor conductor of electricity, which may cause the high overpotential and poor cycle performance for the Na-CO 2 batteries. The promotion of decomposition of Na 2 CO 3 should be an efficient strategy to enhance the electrochemical performance. Here, we design a facile Na 2 CO 3 activation experiment to screen the efficient cathode catalyst for the Na-CO 2 batteries. It is found that the Co 2 MnO x nanowire-decorated carbon fibers (CMO@CF) can promote the Na 2 CO 3 decomposition at the lowest voltage among all these metal oxide-decorated carbon fiber structures. After assembling the Na-CO 2 batteries, the electrodes based on CMO@CF show lower overpotential and better cycling performance compared with the electrodes based on pristine carbon fibers and other metal oxide-modified carbon fibers. We believe this catalyst screening method and the freestanding structure of the CMO@CF electrode may provide an important reference for the development of advanced Na-CO 2 batteries.

  11. NaCl intake and preference threshold of spontaneously hypertensive rats.

    PubMed

    Fregly, M J

    1975-09-01

    Both male and female spontaneously hypertensive (SH) rats have an appetite for NaCl solution. The appetite is present when a choice is offered between distilled water and either isotonic or hypertonic (0.25 M) NaCl solution to drink. Total fluid intake (water plus NaCl solution) was greater for SH rats than for controls while food intakes (g/100 g body wt/day) of SH rats were not different from controls. Mean body weight of SH rats was always less than that of controls. The appetite for NaCl solution was accompanied by a significant reduction in preference (detection) threshold. SH rats could detect the difference between distilled water and NaCl solution when the concentration of the latter was 12 mEq/liter compared to a control threshold of 30 mEq/liter. The NaCl appetite and reduced NaCl preference threshold induced by spontaneous hypertension is in marked contrast to the NaCl aversion induced by other types of experimentally induced hypertension in rats. The mechanism or mechanisms responsible for these differences remain for further study.

  12. High-Pressure Polymorph of NaBiO3.

    PubMed

    Naa, Octavianti; Kumada, Nobuhiro; Miura, Akira; Takei, Takahiro; Azuma, Masaki; Kusano, Yoshihiro; Oka, Kengo

    2016-06-20

    A new high-pressure polymorph of NaBiO3 (hereafter β-NaBiO3) was synthesized under the conditions of 6 GPa and 600 °C. The powder X-ray diffraction pattern of this new phase was indexed with a hexagonal cell of a = 9.968(1) Å and c = 3.2933(4) Å. Crystal structure refinement using synchrotron powder X-ray diffraction data led to RWP = 8.53% and RP = 5.55%, and the crystal structure was closely related with that of Ba2SrY6O12. No photocatalytic activity for phenol decomposition was observed under visible-light irradiation in spite of a good performance for its mother compound, NaBiO3. The optical band-gap energy of β-NaBiO3 was narrower than that of NaBiO3, which was confirmed with density of states curves simulated by first-principles density functional theory calculation.

  13. Na[superscript +] binding to meizothrombin desF1

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Papaconstantinou, M.E.; Gandhi, P.S.; Chen, Z.

    2009-06-10

    Meizothrombin is the physiologically active intermediate generated by a single cleavage of prothrombin at R320 to separate the A and B chains. Recent evidence has suggested that meizothrombin, like thrombin, is a Na{sup +}-activated enzyme. In this study we present the first X-ray crystal structure of human meizothrombin desF1 solved in the presence of the active site inhibitor PPACK at 2.1 {angstrom} resolution. The structure reveals a Na{sup +} binding site whose architecture is practically identical to that of human thrombin. Stopped-flow measurements of Na{sup +} binding to meizothrombin desF1 document a slow phase of fluorescence change with a kmore » obs decreasing hyperbolically with increasing [Na{sup +}], consistent with the existence of three conformations in equilibrium, E*, E and E:Na{sup +}, as for human thrombin. Evidence that meizothrombin exists in multiple conformations provides valuable new information for studies of the mechanism of prothrombin activation.« less

  14. Caries-Preventive Effect of NaF, NaF plus TCP, NaF plus CPP-ACP, and SDF Varnishes on Sound Dentin and Artificial Dentin Caries in vitro.

    PubMed

    Wierichs, Richard J; Stausberg, Sabrina; Lausch, Julian; Meyer-Lueckel, Hendrik; Esteves-Oliveira, Marcella

    2018-01-01

    The aim of this study was to compare the caries-preventive effect of different fluoride varnishes on sound dentin as well as on artificial dentin caries-like lesions. Bovine dentin specimens (n = 220) with one sound surface (ST) and one artificial caries lesion (DT) were prepared and randomly allocated to 11 groups. The interventions before pH cycling were as follows: application of a varnish containing NaF (22,600 ppm F-; Duraphat [NaF0/NaF1]), NaF plus tricalcium phosphate (22,600 ppm F-; Clinpro White Varnish Mint [TCP0/TCP1]), NaF plus casein phosphopeptide-stabilized amorphous calcium phosphate complexes (CPP-ACP; 22,600 ppm F-; MI Varnish [CPP0/CPP1]), or silver diamine fluoride (SDF; 35,400 ppm F-; Cariestop 30% [SDF0/SDF1]) and no intervention (NNB/N0/N1). During pH cycling (14 days, 6 × 120 min demineralization/day) half of the specimens in each group were brushed (10 s; 2 times/day) with either fluoride-free ("0"; e.g., TCP0) or 1,100 ppm F- ("1"; e.g., TCP1) dentifrice slurry. In another subgroup, the specimens were pH cycled but not brushed (NNB). Differences in integrated mineral loss (ΔΔZ), lesion depth (ΔLD), and colorimetric values (ΔΔE) were calculated between the values after initial demineralization and those after pH cycling, using transversal microradiography and photographic images. After pH cycling, no discoloration could be observed. Furthermore, NNB, N0, and N1 showed significantly increased ΔZDT/LDDT and ΔZST/LDST values, indicating further demineralization. In contrast, CPP0, CPP1, SDF0, and SDF1 showed significantly decreased ΔZDT/LDDT values, indicating remineralization (p ≤ 0.004; paired t test). CPP0, CPP1, SDF0, and SDF1 showed significantly higher changes in ΔΔZDT/ΔLDDT and ΔΔZST/ΔLDST than NNB, N0, and N1 (p < 0.001; Bonferroni post hoc test). In conclusion, under the conditions chosen, all fluoride varnishes prevented further demineralization. However, only NaF plus CPP-ACP and SDF could remineralize artificial

  15. Serologic survey of infectious diseases in populations of maned wolf (Chrysocyon brachyurus) and crab-eating fox (Cerdocyon thous) from Aguas Emendadas Ecological Station, Brazil.

    PubMed

    Proença, Laila M; Silva, Jean C R; Galera, Paula D; Lion, Marília B; Marinho-Filho, Jader S; Ragozo, Alessandra Mara Alves; Gennari, Solange Maria; Dubey, J P; Vasconcellos, Silvio Arruda; Souza, Gisele Oliveira; Pinheiro, José Wilton; Santana, Vânia Lúcia de Assis; França, Gilvan L; Rodrigues, Flávio H G

    2013-03-01

    Domestic dogs are reservoirs for many infectious diseases and may represent a potential source of infection for wild canid populations. A serologic investigation of antibodies to Toxoplasma gondii, Neospora caninum, Brucella abortus, and Leptospira spp. was conducted on three maned wolves (Chrysocyon brachyurus) and seven crab-eating foxes (Cerdocyon thous), all free-living, at the Aguas Emendadas Ecological Station (ESECAE), Federal District, Brazil, between February and October 2006. Out of the 10 samples analyzed, eight (80%) were seropositive for T. gondii: 3/3 (100%) of the maned wolves and 5/7 (71.4%) of the crab-eating foxes. None of the animals presented anti-N. caninum, B. abortus, and Leptospira spp. antibodies. This study demonstrated that the wild canid populations at ESECAE presented high exposure to T. gondii and indicated that there is high environmental contamination at the Station, which can be attributed to its proximity to urban zones, the presence of domestic cats in the study area, or the existence of other wild infected felines.

  16. 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.

  17. Enhanced upconversion emission in colloidal (NaYF4:Er(3+))/NaYF4 core/shell nanoparticles excited at 1523 nm.

    PubMed

    Shao, Wei; Chen, Guanying; Damasco, Jossana; Wang, Xianliang; Kachynski, Aliaksandr; Ohulchanskyy, Tymish Y; Yang, Chunhui; Ågren, Hans; Prasad, Paras N

    2014-03-15

    In this work, we report on efficient visible and near-IR upconversion emissions in colloidal hexagonal-phase core/shell NaYF4:Er(3+)/NaYF4 nanoparticles (∼38  nm) under IR laser excitation at 1523 nm. Varying amounts of Er(3+) dopants were introduced into the core NaYF4:Er(3+) nanoparticles, revealing an optimized Er(3+) concentration of 10% for the highest luminescent efficiency. An inert epitaxial shell layer of NaYF4 grown onto the core of the NaYF4:Er(3+) 10% nanoparticle increased its upconversion emission intensity fivefold due to suppression of surface-related quenching mechanisms, yielding the absolute upconversion efficiency to be as high as ∼3.9±0.3% under an excitation density of 18  W/cm(2). The dependence of the intensity of upconversion emission peaks on laser excitation density in the core/shell nanoparticle displayed "saturation effects" at low excitation density in the range of 1.5-18  W/cm(2), which again demonstrates high upconversion efficiency.

  18. Constraining the astrophysical 23Mg(p, γ)24Al reaction rate using the 23Na(d,p)24Na reaction

    NASA Astrophysics Data System (ADS)

    Bennett, E. A.; Catford, W. N.; Christian, G.; Dede, S.; Hallam, S.; Lotay, G.; Ota, S.; Saastamoinen, A.; Wilkinson, R.

    2017-09-01

    The 23Mg(p, γ)24Al reaction provides an escape from the Ne-Na cycle in classical novae and is therefore important in understanding nova nucleosynthesis in the A > 20 mass range. Although several resonances may contribute to the overall rate at novae temperatures, the resonance at 475 keV is thought to be dominant. The strength of this resonance has been directly measured using a radioactive 23Mg beam impinging on a windowless H2 gas target; however, recent high-precision 24Al mass measurements have called this result into question. Here we make an indirect measurement using the 23Na(d,p)24Na reaction in inverse kinematics to study the mirror state of the 475 keV resonance in 24Na. The experiment, performed at the Texas A&M Cyclotron Institute, utilized the TIARA silicon array, four HPGe detectors, and the MDM spectrometer to measure the excited states of the 24Na nucleus. Preliminary results from the experiment will be presented along with progress from the ongoing analysis.

  19. Growth responses and ion accumulation in the halophytic legume Prosopis strombulifera are determined by Na2SO4 and NaCl.

    PubMed

    Reginato, M; Sosa, L; Llanes, A; Hampp, E; Vettorazzi, N; Reinoso, H; Luna, V

    2014-01-01

    Halophytes are potential gene sources for genetic manipulation of economically important crop species. This study addresses the physiological responses of a widespread halophyte, Prosopis strombulifera (Lam.) Benth to salinity. We hypothesised that increasing concentrations of the two major salts present in soils of central Argentina (Na2SO4, NaCl, or their iso-osmotic mixture) would produce distinct physiological responses. We used hydroponically grown P. strombulifera to test this hypothesis, analysing growth parameters, water relations, photosynthetic pigments, cations and anions. These plants showed a halophytic response to NaCl, but strong general inhibition of growth in response to iso-osmotic solutions containing Na2SO4. The explanation for the adaptive success of P. strombulifera in high NaCl conditions seems to be related to a delicate balance between Na(+) accumulation (and its use for osmotic adjustment) and efficient compartmentalisation in vacuoles, the ability of the whole plant to ensure sufficient K(+) supply by maintaining high K(+)/Na(+) discrimination, and maintenance of normal Ca(2+) levels in leaves. The three salt treatments had different effects on the accumulation of ions. Findings in bi-saline-treated plants were of particular interest, where most of the physiological parameters studied showed partial alleviation of SO4(2-)-induced toxicity by Cl(-). Thus, discussions on physiological responses to salinity could be further expanded in a way that more closely mimics natural salt environments. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  20. Elaboration and characterization of solid materials of types zeolite NaA and faujasite NaY exchanged by zinc metallic ions Zn2+

    NASA Astrophysics Data System (ADS)

    Nibou, D.; Amokrane, S.; Mekatel, H.; Lebaili, N.

    2009-11-01

    The present work deals with the elaborated of NaA and faujasite NaY solid materials according to a hydrothermal crystallization of amorphous gels composed of solutions of silicon, aluminum and sodium. The process elaboration has been achieved in autoclaves made of steel lined in Teflon under different operating conditions of temperature of heating, time of contact and stirring. After crystallization, the samples were characterized by different techniques such as X ray diffraction, scanning electronic microscopy, infrared spectroscopy, thermal analysis, and chemical analysis. Pure solid materials NaA and NaY zeolites were obtained and were impregnated by (Zn2+) ions by ion exchange process. The effects of various parameters such as initial metal concentration, pH, solid-liquid ratio (R) and temperature on the exchange percentage are studied. The equilibrium isotherms of zinc ions sorption are also evaluated using Langmuir and Freundlich models. Thermodynamic parameters, i.e. enthalpy of adsorption ΔHads∘, entropy change ΔSads∘ and Gibbs free energy ΔGads∘ for the sorption of zinc ions on NaA and NaY zeolites were examined.

  1. The system Na2CO3-CaCO3 at 3 GPa

    NASA Astrophysics Data System (ADS)

    Podborodnikov, Ivan V.; Shatskiy, Anton; Arefiev, Anton V.; Rashchenko, Sergey V.; Chanyshev, Artem D.; Litasov, Konstantin D.

    2018-04-01

    It was suggested that alkali-alkaline earth carbonates may have a substantial role in petrological processes relevant to metasomatism and melting of the Earth's mantle. Because natrite, Na2CO3, Na-Ca carbonate (shortite and/or nyerereite), and calcite, CaCO3, have been recently reported from xenoliths of shallow mantle (110-115 km) origin, we performed experiments on phase relations in the system Na2CO3-CaCO3 at 3 GPa and 800-1300 °C. We found that the system has one intermediate compound, Na2Ca3(CO3)4, at 800 °C, and two intermediate compounds, Na2Ca(CO3)2 and Na2Ca3(CO3)4, at 850 °C. CaCO3 crystals recovered from experiments at 950 and 1000 °C are aragonite and calcite, respectively. Maximum solid solution of CaCO3 in Na2CO3 is 20 mol% at 850 °C. The Na-carbonate-Na2Ca(CO3)2 eutectic locates near 860 °C and 56 mol% Na2CO3. Na2Ca(CO3)2 melts incongruently near 880 °C to produce Na2Ca3(CO3)4 and a liquid containing about 51 mol% Na2CO3. Na2Ca3(CO3)4 disappears above 1000 °C via incongruent melting to calcite and a liquid containing about 43 mol% Na2CO3. At 1050 °C, the liquid, coexisting with Na-carbonate, contains 87 mol% Na2CO3. Na-carbonate remains solid up to 1150 °C and melts at 1200 °C. The Na2CO3 content in the liquid coexisting with calcite decreases to 15 mol% as temperature increases to 1300 °C. Considering the present and previous data, a range of the intermediate compounds on the liquidus of the Na2CO3-CaCO3 join changes as pressure increases in the following sequence: Na2Ca(CO3)2 (0.1 GPa) → Na2Ca(CO3)2, Na2Ca3(CO3)4 (3 GPa) → Na4Ca(CO3)3, Na2Ca3(CO3)4 (6 GPa). Thus, the Na2Ca(CO3)2 nyerereite stability field extends to the shallow mantle pressures. Consequently, findings of nyerereite among daughter phases in the melt inclusions in olivine from the sheared garnet peridotites are consistent with their mantle origin.

  2. Groundwater demand management at local scale in rural areas of India: a strategy to ensure water well sustainability based on aquifer diffusivity and community participation

    NASA Astrophysics Data System (ADS)

    Kulkarni, Himanshu; Vijay Shankar, P. S.; Deolankar, S. B.; Shah, Mihir

    Watershed development programmes provide an opportunity for sustainable management strategies, although currently, they remain largely `supply-side' mechanisms of water resources development. Hydrogeological conditions, community participation and status of groundwater usage are important in evolving strategies on `demand-side' groundwater management. Neemkheda aquifer is a typical low-storage, low-hydraulic conductivity aquifer from a watershed in the dryland regions of Madhya Pradesh State of central India. A shallow unconfined aquifer, it consists of an upper coarse, calcareous sandstone unit underlain by a fine-grained sandstone unit. A `well commune' of seven wells is poised to test the concept of joint groundwater management, wherein wells are mechanisms of tapping a common water source, the Neemkheda aquifer. The strategy for systematic groundwater management in the Neemkheda well commune is based upon the relationship between Transmissivity (T) and Storage coefficient (S), i.e. aquifer diffusivity, and its variation within the aquifer. Wells within a high diffusivity domain tend to dewater more quickly than wells within a low diffusivity domain. A well-use schedule during the dry season, based upon aquifer diffusivity forms the basis of the groundwater management concept. The distribution of local aquifer diffusivities governs the relationship between local and regional aquifer depletion times and forms the basis of the groundwater management exercise being proposed for the Neemkheda aquifer. Los programas de desarrollo de una cuenca hídrica son una oportunidad para el uso de estrategias de gestión sostenible, aunque hoy en día estas siguen siendo principalmente mecanismos para el desarrollo de recursos hídricos con énfasis en la ``oferta''. Las condiciones hidrogeológicas, la participación comunitaria y la condición de utilización del agua subterránea, son importantes en el desarrollo de estrategias para la gestión del agua subterránea, desde

  3. Arsenic contamination of groundwater: Mitigation strategies and policies

    NASA Astrophysics Data System (ADS)

    Alaerts, Guy J.; Khouri, Nadim

    affectées dans les pays en développement. Un cadre d'ensemble pour lutter contre la dégradation naturelle des ressources est associé à des études de cas au Chili, au Mexique, au Bangladesh et ailleurs afin d'établir un ensemble de recommandations stratégiques pour les dimensions globale, nationale et locale de la «crise» de l'arsenic. Les principales recommandations sont les suivantes: le besoin d'une flexibilité pour élaborer une stratégie de diminution de l'arsenic, l'amélioration et l'utilisation à grande échelle de techniques peu coûteuses et associant les populations pour tester la qualité de l'eau souterraine, le besoin de maintenir un usage logique des leçons clés acquises de par le monde pour l'alimentation en eau et la santé publique, celui d'intégrer l'arsenic simplement comme un autre facteur pour assurer une alimentation durable en eau, et pour suivre des pistes distinctes mais communicables entre les développements liés à l'arsenic et les alimentations durables en eau mises en valeurs à long terme. La contaminación de las aguas subterráneas con arsénico procedente de fuentes geoquímicas naturales es actualmente uno de los retos principales de la planificación a gran escala de las aguas subterráneas para uso de boca y otros fines. Las recientes mejoras en los límites de detección del instrumental analítico permiten correlacionar impactos en la salud tales como el cáncer con concentraciones elevadas de arsénico en las aguas subterráneas. Sin embargo, a fecha de hoy no existen soluciones tecnológicas de gran escala para millones de personas-población principalmente rural-que están potencialmente afectadas en los países en vías de desarrollo. Se combina un enfoque general para combatir la degradación de los recursos naturales con estudios concretos de Chile, México, Bangladesh y cualquier otro lugar que permita obtener un conjunto de recomendaciones estratégicas para las dimensiones global, nacional y local de la

  4. Robust high pressure stability and negative thermal expansion in sodium-rich antiperovskites Na{sub 3}OBr and Na{sub 4}OI{sub 2}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yonggang, E-mail: yyggwang@gmail.com, E-mail: yangwg@hpstar.ac.cn, E-mail: yusheng.zhao@unlv.edu; Institute of Nanostructured Functional Materials, Huanghe Science and Technology College, Zhengzhou, Henan 450006; High Pressure Synergetic Consortium

    2016-01-14

    The structure stability under high pressure and thermal expansion behavior of Na{sub 3}OBr and Na{sub 4}OI{sub 2}, two prototypes of alkali-metal-rich antiperovskites, were investigated by in situ synchrotron X-ray diffraction techniques under high pressure and low temperature. Both are soft materials with bulk modulus of 58.6 GPa and 52.0 GPa for Na{sub 3}OBr and Na{sub 4}OI{sub 2}, respectively. The cubic Na{sub 3}OBr structure and tetragonal Na{sub 4}OI{sub 2} with intergrowth K{sub 2}NiF{sub 4} structure are stable under high pressure up to 23 GPa. Although being a characteristic layered structure, Na{sub 4}OI{sub 2} exhibits nearly isotropic compressibility. Negative thermal expansion was observed at lowmore » temperature range (20–80 K) in both transition-metal-free antiperovskites for the first time. The robust high pressure structure stability was examined and confirmed by first-principles calculations among various possible polymorphisms qualitatively. The results provide in-depth understanding of the negative thermal expansion and robust crystal structure stability of these antiperovskite systems and their potential applications.« less

  5. Effect of salts (NaCl and Na2CO3) on callus and suspension culture of Stevia rebaudiana for Steviol glycoside production.

    PubMed

    Gupta, Pratibha; Sharma, Satyawati; Saxena, Sanjay

    2014-03-01

    Steviol glycosides are natural non-caloric sweeteners which are extracted from the leaves of Stevia rebaudiana plant. Present study deals the effect of salts (NaCl and Na2CO3) on callus and suspension culture of Stevia plant for steviol glycoside (SGs) production. Yellow-green and compact calli obtained from in vitro raised Stevia leaves sub-cultured on MS medium supplemented with 2.0 mg l(-1) NAA and different concentrations of NaCl (0.05-0.20%) and Na2CO3 (0.0125-0.10%) for 2 weeks, and incubated at 24 ± 1 °C and 22.4 μmol m(-2) s(-1) light intensity provided by white fluorescent tubes for 16 h. Callus and suspension biomass cultured on salts showed less growth as well as browning of medium when compared with control. Quantification of SGs content in callus culture (collected on 15th day) and suspension cultures (collected at 10th and 15th days) treated with and without salts were analyzed by HPLC. It was found that abiotic stress induced by the salts increased the concentration of SGs significantly. In callus, the quantity of SGs got increased from 0.27 (control) to 1.43 and 1.57% with 0.10% NaCl, and 0.025% Na2CO3, respectively. However, in case of suspension culture, the same concentrations of NaCl and Na2CO3 enhanced the SGs content from 1.36 (control) to 2.61 and 5.14%, respectively, on the 10th day.

  6. Raman spectroscopic study of synthesized Na-bearing majoritic garnets

    NASA Astrophysics Data System (ADS)

    Okamoto, K.

    2003-12-01

    Majoritic garnets in diamond have been considered as the sample from mantle transition zone (e.g. Moore and Gurney, 1985). For non-destructive, in-situ Raman analysis, Gillet et al. (2002) systematically checked chemistry and Raman peak of various majoritic garnets in diamond. They treated majoritic component as number of excess-silica than 3.0 per formula unit. However, in the basaltic system, majorite garnets also have significant amounts of Na. Na substitution is coupled with Si and Ti as follows; Na +Ti = Ca +Al (Ringwood and Lovering, 1970), Na +Si = Ca + Al (Sobolev and Labrentav, 1971; Ringwood and Major, 1971) or Na + Si = Mg + Al (Gasparik, 1989). Each component in garnet is defined as follows; Mj (majorite) component = ((Si-3)-Na)/2), NaSi (Na2MSi5O12 where M= Ca, Mg, Fe2+) component = (Na-T)/2, and NaTi component = Ti/2. Okamoto and Maruyama (2003) conducted UHP experiments in the MORB + H2O system (KNCFMATSH) at 10-19 GPa. They show that 1) Mj and NaTi component are constant and lower than 0.1 at T = 900 \\deg C, and 2) NaSi component increases drastically above 15 GPa although it is neglibly small at P<15 GPa. Raman spectra was newly analyzed using Okamoto and Maruyama (2003)'s run charges. Above 15 GPa, there is a characteristic sharp peak at 910 cm-1 and broad shoulder between 800 and 900 cm-1 as well as broad band near 960 cm-1. Gillet et at (2002) concluded that the former peak at 910cm-1 is the only reliable signature for the majoritic garnet (Si>3). They also implied that the latter two broad peaks are diagnostic feature for Ti rich garnet (> 1wt% of TiO2) as well as peak at 1030 cm-1. However, in all P range (10-19 GPa) of the present study, TiO2 is higher than 1wt%, and there is a peak at 1030 cm-1. Additional Ti-free experiment at 16 GPa, 1200 \\deg C clearly revealed that Na-bearing majoritic garnet has a significant shoulder at 800-900 cm-1. Ref; Gasparik (1989) CMP, 102,389, Gillet et al. (2002) Am.Min., 87, 312, Moore and Gurney (1985

  7. Thermodynamic Study of Solid-Liquid Equilibrium in NaCl-NaBr-H2O System at 288.15 K

    NASA Astrophysics Data System (ADS)

    Li, Dan; Meng, Ling-zong; Deng, Tian-long; Guo, Ya-fei; Fu, Qing-Tao

    2018-06-01

    The solubility data, composition of the solid solution and refractive indices of the NaCl-NaBr-H2O system at 288.15 K were studied with the isothermal equilibrium dissolution method. The solubility diagram and refractive index diagram of this system were plotted at 288.15 K. The solubility diagram consists of two crystallization zones for solid solution Na(Cl,Br) · 2H2O and Na(Cl,Br), one invariant points cosaturated with two solid solution and two univariant solubility isothermal curves. On the basis of Pitzer and Harvie-Weare (HW) chemical models, the composition equations and solubility equilibrium constant equations of the solid solutions at 288.15 K were acquired using the solubility data, the composition of solid solutions, and binary Pitzer parameters. The solubilities calculated using the new method combining the equations are in good agreement with the experimental data.

  8. 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.

  9. 33 CFR 147.833 - Na Kika FDS safety zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Na Kika FDS safety zone. 147.833 Section 147.833 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.833 Na Kika FDS safety zone. (a) Description. Na...

  10. 33 CFR 147.833 - Na Kika FDS safety zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Na Kika FDS safety zone. 147.833 Section 147.833 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OUTER CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.833 Na Kika FDS safety zone. (a) Description. Na...

  11. Intracellular Requirements for Passive Proton Transport through the Na+,K+-ATPase.

    PubMed

    Stanley, Kevin S; Meyer, Dylan J; Gatto, Craig; Artigas, Pablo

    2016-12-06

    The Na + ,K + -ATPase (NKA or Na/K pump) hydrolyzes one ATP to exchange three intracellular Na+ (Na + i ) for two extracellular K+ (K + o ) across the plasma membrane by cycling through a set of reversible transitions between phosphorylated and dephosphorylated conformations, alternately opening ion-binding sites externally (E2) or internally (E1). With subsaturating [Na + ] o and [K + ] o , the phosphorylated E2P conformation passively imports protons generating an inward current (I H ), which may be exacerbated in NKA-subunit mutations associated with human disease. To elucidate the mechanisms of I H , we studied the effects of intracellular ligands (transported ions, nucleotides, and beryllium fluoride) on I H and, for comparison, on transient currents measured at normal Na + o (Q Na ). Utilizing inside-out patches from Xenopus oocytes heterologously expressing NKA, we observed that 1) in the presence of Na + i , I H and Q Na were both activated by ATP, but not ADP; 2) the [Na + ] i dependence of I H in saturating ATP showed K 0.5,Na  = 1.8 ± 0.2 mM and the [ATP] dependence at saturating [Na + ] i yielded K 0.5,ATP  = 48 ± 11 μM (in comparison, Na + i -dependent Q Na yields K 0.5,Na  = 0.8 ± 0.2 mM and K 0.5,ATP  = 0.43 ± 0.03 μM; 3) ATP activated I H in the presence of K + i (∼15% of the I H observed in Na + i ) only when Mg 2+ i was also present; and 4) beryllium fluoride induced maximal I H  even in the absence of nucleotide. These data indicate that I H occurs when NKA is in an externally open E2P state with nucleotide bound, a conformation that can be reached through forward Na/K pump phosphorylation of E1, with Na + i and ATP, or by backward binding of K + i to E1, which drives the pump to the occluded E2(2K), where free P i (at the micromolar levels found in millimolar ATP solutions) promotes external release of occluded K + by backdoor NKA phosphorylation. Maximal I H through beryllium-fluorinated NKA indicates that this complex mimics ATP

  12. Dependence of renal (Na+ + k+)-adenosine triphosphatase activity on thyroid status.

    PubMed

    Lo, S C; August, T R; Liberman, U A; Edelman, I S

    1976-12-25

    In thyroidectomized rats, a single injection of L-2,,5,2'-triiodothyronine (T3) (50mug/100 g body weight) elicited at 45% increase in (Na+ + k+)-dependent adenosine triphosphatase (NaK-ATPase) activity of the membrane-rich fraction of renal cortex at the optimal time of response, 48 h after injection. Three successive doses of T3 (50 mug/100 g body weight), given on alternate days, increased NaK-ATPase by 67% in the renal cortex but had no significant effect on the outer medulla or the papilla. Moreover, T3 had no effect on Mg2+-dependent adenosine trisphatase (MgATPase) in cortex, cedulla, or papilla. Three doses of T3 (50 mug/100 g body weight) given on alternate days to thyroidectomized rats elecited a 134, 79, and 46% increase in Vmax for ATP, Na4, and K+, respectively. There were no changes in the Km for ATP or the K1/2 values for Na+ and K+. Two methods were used to estimate the effect of T3 on the number of NaK-ATPase units (assumed to represent the number of Na+ pump sites); rat renal plasma membrane fractions were incubated with [gamma-32P]ATP, Mg2+, and Na+; the 32P-labeled membrane protein yeild was quantitatively dependent on Na+ and was hydrolyzed on addition of K+. There was a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of phosphorylated intermediate formed, in renal cortical membrane fractions from thyroidectomized rats given T3 or the diluent. There was also a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of [3H]ouabain specifically bound (Na+-, Mg2+-, APT-dependent) to the NaK-ATPase preparation. Injection of T3 resulted in a 70% increase in NaK-ATPase activity, a 79% increase in formation of the phosphorylated intermediate, and a 65% increase in the [H]ouabain specifically bound to the NaK-ATPase system. The T3-dependent increases in Vmax for ATP, Na+, and K+ and the proportionate increases in the phosphorylated intermediate and in the amount of [3H]ouabain bound

  13. Risk factors for left ventricular hypertrophy: role of Na(+)-Li+ countertransport.

    PubMed

    Neves, P L; Faisca, M; Gomes, V; Cacodcar, S; Bernardo, I; Anunciada, A I; Viegas, E; Martins, H; da Silva, A M

    1996-06-01

    Left ventricular hypertrophy (LVH) is associated with an increase in cardiovascular death in essential hypertension (EH). The factors involved in LVH are multiple and complex. We looked for risk factors of LVH in a group of 28 nonobese patients with EH (mean age = 45.3 years). We analyzed the activity of several erythrocyte ion transports (Vmax of NaLi countertransport, NaKCl cotransport and NaK-pump, and the Na-leak Kp Na), the intracellular Na and the insulin sensitivity index. All these parameters were used as independent variables whereas the left ventricular mass index (LVMI) was used as the dependent variable. Variables showing a significant univariate correlation (age, time of EH, mean blood pressure and Vmax of NaLi countertransport) were introduced in a stepwise multiple regression model. Only age (P = 0.014), time of EH (P = 0.038) and Vmax of NaLi countertransport (P = 0.032) were independently associated with LVMI (R2 = 0.581, P = 0.0001). The NaLi CT, an operating mode of the NaH exchanger that facilitates cellular growth, may be a marker of LVH, and consequently a marker of increased cardiovascular risk.

  14. Effect of Solids-To-Liquids, Na2SiO3-To-NaOH and Curing Temperature on the Palm Oil Boiler Ash (Si + Ca) Geopolymerisation System

    PubMed Central

    Yahya, Zarina; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Abd Razak, Rafiza; Sandu, Andrei Victor

    2015-01-01

    This paper investigates the effect of the solids-to-liquids (S/L) and Na2SiO3/NaOH ratios on the production of palm oil boiler ash (POBA) based geopolymer. Sodium silicate and sodium hydroxide (NaOH) solution were used as alkaline activator with a NaOH concentration of 14 M. The geopolymer samples were prepared with different S/L ratios (0.5, 1.0, 1.25, 1.5, and 1.75) and Na2SiO3/NaOH ratios (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0). The main evaluation techniques in this study were compressive strength, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM). The results showed that the maximum compressive strength (11.9 MPa) was obtained at a S/L ratio and Na2SiO3/NaOH ratio of 1.5 and 2.5 at seven days of testing.

  15. Na intercalation in Fe-MIL-100 for aqueous Na-ion batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chavez, James S.; Harrison, Katharine L.; Sava Gallis, Dorina F.

    Here we report for the first time the feasibility of using metal–organic frameworks (MOFs) as electrodes for aqueous Na-ion batteries. We show that Fe-MIL-100, a known redox-active MOF, is electrochemically active in a Na aqueous electrolyte, under various compositions. Emphasis was placed on investigating the electrode–electrolyte interface, with a focus on identifying the relationship between additives in the composition of the working electrode, particle size and overall performance. We found that the energy storage capacity is primarily dependent on the binder additive in the composite; the best activity for this MOF is obtained with Nafion as a binder, owing tomore » its hydrophilic and ion conducting nature. Kynar-bound electrodes are clearly less effective, due to their hydrophobic character, which impedes wetting of the electrode. The binder-free systems show the poorest electrochemical activity. There is little difference in the overall performance as function of particle size (micro vs. nano), implying the storage capacities in this study are not limited by ionic and/or electronic conductivity. Excellent reversibility and high coulombic efficiency are achieved at higher potential ranges, observed after cycle 20. That is despite progressive capacity decay observed in the initial cycles. Importantly, structural analyses of cycled working electrodes confirm that the long range crystallinity remains mainly unaltered with cycling. These findings suggest that limited reversibility of the intercalated Na ions in the lower potential range, together with the gradual lack of available active sites in subsequent cycles is responsible for the rapid decay in capacity retention.« less

  16. Na intercalation in Fe-MIL-100 for aqueous Na-ion batteries

    DOE PAGES

    Chavez, James S.; Harrison, Katharine L.; Sava Gallis, Dorina F.

    2017-05-04

    Here we report for the first time the feasibility of using metal–organic frameworks (MOFs) as electrodes for aqueous Na-ion batteries. We show that Fe-MIL-100, a known redox-active MOF, is electrochemically active in a Na aqueous electrolyte, under various compositions. Emphasis was placed on investigating the electrode–electrolyte interface, with a focus on identifying the relationship between additives in the composition of the working electrode, particle size and overall performance. We found that the energy storage capacity is primarily dependent on the binder additive in the composite; the best activity for this MOF is obtained with Nafion as a binder, owing tomore » its hydrophilic and ion conducting nature. Kynar-bound electrodes are clearly less effective, due to their hydrophobic character, which impedes wetting of the electrode. The binder-free systems show the poorest electrochemical activity. There is little difference in the overall performance as function of particle size (micro vs. nano), implying the storage capacities in this study are not limited by ionic and/or electronic conductivity. Excellent reversibility and high coulombic efficiency are achieved at higher potential ranges, observed after cycle 20. That is despite progressive capacity decay observed in the initial cycles. Importantly, structural analyses of cycled working electrodes confirm that the long range crystallinity remains mainly unaltered with cycling. These findings suggest that limited reversibility of the intercalated Na ions in the lower potential range, together with the gradual lack of available active sites in subsequent cycles is responsible for the rapid decay in capacity retention.« less

  17. High Pressure Strength Study on NaCl

    NASA Astrophysics Data System (ADS)

    Mi, Z.; Shieh, S. R.; High Pressure Mineral Physics Group

    2010-12-01

    Yield strength is regarded as one important property related to rheological characteristics of minerals in the Earth’s interior. The strength study of NaCl, a popular pressure medium in static high pressure experiments, has been carried out under non-hydrostatic conditions in a diamond anvil cell up to 43 GPa at room temperature using radial energy dispersive X-ray diffraction technique. Phase transformation from B1 (rock salt structure) to B2 (CsCl structure) starts at 29.4 GPa, and is complete at 32.1 GPa. Bulk modulus obtained by third order Birch-Manurgham equation of state is 25.5 GPa with pressure derivative 4.6 for B1 phase, and 30.78 GPa with pressure derivative 4.32 GPa for B2 phase, which are in a good agreement with previous studies. The differential stress of NaCl B1 phase shows very gentle increase with pressure, which indicates that NaCl is a very good pressure-transmitting medium at pressure below 30 GPa. However, the differential stress increases more abruptly for B2 phase and this may imply that NaCl can no longer be regarded as a “soft” pressure medium at very high pressures. For B1 phase, (111) is the strongest plane and (200) is the weakest plane, while (200) becomes the strongest plane in B2 phase. Pure NaCl is weaker than mixture MgO and NaCl, which indicates that soft material become stronger when mixed with hard material. The yield strength of B2 obtained through energy dispersive X-ray diffraction technique increase linearly, while the value derived by pressure gradient method shows jagged trend.

  18. Mercury Na exospheric emission related to solar disturbances

    NASA Astrophysics Data System (ADS)

    Orsini, S.; Mangano, V.; Milillo, A.; Plainaki, C.; Mura, A.; Massetti, S.; Raines, J. M.; De Angelis, E.; Rispoli, R.; Lazzarotto, F.; Aronica, A.

    2017-09-01

    A first attempt to use Na exospheric emission at Mercury as a proxy of CME transit is presented, in a kind of planetary space weather. The link existing between the dayside exosphere Na pattern at Mercury and the solar wind-magnetosphere-surface interactions is investigated. This goal is pursued by analyzing the Na hourly average distributions, as observed by the ground-based THEMIS solar telescope during 10 selected periods between 2012 and 2013 (seeing <2"), when also data from MESSENGER were available. Very often a two-peak pattern of variable intensity is observed, symmetrically located at high latitudes in both hemispheres. Occasionally, the signal is instead diffused above the sub-solar region. We compare these different Na emission patterns with the time profiles of proton fluxes and magnetic field data, as measured in-situ by MESSENGER. Among these 10 cases, only in one occasion the Na signal is all the time diffused above the subsolar region, and only in this case the MESSENGER data indicate the occurrence of significant solar CME perturbations.

  19. Localization and Function of the Membrane-bound Riboflavin in the Na+-translocating NADH:Quinone Oxidoreductase (Na+-NQR) from Vibrio cholerae*

    PubMed Central

    Casutt, Marco S.; Huber, Tamara; Brunisholz, René; Tao, Minli; Fritz, Günter; Steuber, Julia

    2010-01-01

    The sodium ion-translocating NADH:quinone oxidoreductase (Na+-NQR) from the human pathogen Vibrio cholerae is a respiratory membrane protein complex that couples the oxidation of NADH to the transport of Na+ across the bacterial membrane. The Na+-NQR comprises the six subunits NqrABCDEF, but the stoichiometry and arrangement of these subunits are unknown. Redox-active cofactors are FAD and a 2Fe-2S cluster on NqrF, covalently attached FMNs on NqrB and NqrC, and riboflavin and ubiquinone-8 with unknown localization in the complex. By analyzing the cofactor content and NADH oxidation activity of subcomplexes of the Na+-NQR lacking individual subunits, the riboflavin cofactor was unequivocally assigned to the membrane-bound NqrB subunit. Quantitative analysis of the N-terminal amino acids of the holo-complex revealed that NqrB is present in a single copy in the holo-complex. It is concluded that the hydrophobic NqrB harbors one riboflavin in addition to its covalently attached FMN. The catalytic role of two flavins in subunit NqrB during the reduction of ubiquinone to ubiquinol by the Na+-NQR is discussed. PMID:20558724

  20. Physical Biologycal Interactions Controlling Larvae Dispersion: Application to Regions in the Neighbourhood of the Estuaries of North Portugal

    NASA Astrophysics Data System (ADS)

    Almeida, Martinho Marta

    Um modelo numerico tridimensional oceânico foi usado para estudar a influencia das condicoes fisicas na dispersao e recrutamento de larvas com migracao vertical diaria (MVD) activa na plataforma continental noroeste de Portugal. As primeiras simulacoes foram forcadas por mares e verificou-se que a interaccao entre MVD e correntes de mare nao e importante para o transporte de larvas na plataforma continental oeste portuguesa. O trabalho realizado com forcamento de mares incrementou o presente conhecimento da dinâmica da mare na regiao. A analise da variacao vertical dos parâmetros das elipses de mare mostra uma separacao clara entre os harmonicos diurnos e semi-diurnos, e entre a circulacao oceânica quase barotropica e as correntes com dependencia vertical na plataforma. Desprezando a interaccao entre MVD e as mares o proximo passo foi a construcao e validacao dum modelo realistico forcado por fluxos atmosfera-oceano, capaz de reproduzir as correntes dominantes, geradas pelo vento, na plataforma continental. Na configuracao criada a MVD das larvas foi simulada com quatro cenarios de distribuicao e migracao vertical. Foram feitas duas simulacoes, uma para o final do Inverno e outra para a Primavera, abrangendo os meses de Fevereiro a Abril e Abril a Junho de 2002. Estes periodos foram escolhidos pois exibem diferentes regimes de vento, nao favoravel e favoravel ao afloramento costeiro. Os resultados mostram que as particulas com MVD sofreram maior retencao na plataforma continental interna durante condicoes de afloramento do que em qualquer outra combinacao de cenario de migracao e regime de vento. Na costa noroeste da Peninsula Iberica, que nao exibe irregularidades topograficas que poderiam criar areas de concentracao e retencao, a MVD pode constituir um mecanismo importante para evitar a dispersao de larvas em direccao ao mar aberto. None

  1. Growth mechanism and magnetic and electrochemical properties of Na{sub 0.44}MnO{sub 2} nanorods as cathode material for Na-ion batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Demirel, S.; Oz, E.; Altin, E.

    Nanorods of Na{sub 0.44}MnO{sub 2} are a promising cathode material for Na-ion batteries due to their large surface area and single crystalline structure. We report the growth mechanism of Na{sub 0.44}MnO{sub 2} nanorods via solid state synthesis and their physical properties. The structure and the morphology of the Na{sub 0.44}MnO{sub 2} nanorods are investigated by X-ray diffraction (XRD), scanning and tunneling electron microscopy (SEM and TEM), and energy-dispersive X-ray (EDX) techniques. The growth mechanism of the rods is investigated and the effects of vapor pressure and partial melting of Na-rich regions are discussed. The magnetic measurements show an antiferromagnetic phasemore » transition at 25 K and the μ{sub eff} is determined as 3.41 and 3.24 μ{sub B} from the χ–T curve and theoretical calculation, respectively. The electronic configuration and spin state of Mn{sup 3+} and Mn{sup 4+} are discussed in detail. The electrochemical properties of the cell fabricated using the nanorods are investigated and the peaks in the voltammogram are attributed to the diffusion of Na ions from different sites. Na intercalation process is explained by one and two Margules and van Laar models. - Highlights: • We synthesized Na{sub 0.44}MnO{sub 2} nanorods via a simple solid state reaction technique. • Our studies show that excess Na plays a crucial role in the nanorod formation. • Magnetization measurements show that Mn{sup 3+} ions are in LS and HS states. • The electrochemical properties of the cell fabricated using the nanorods are investigated. • Na intercalation process is explained by one and two Margules and van Laar models.« less

  2. Inclusion of Astronomy Themes in an Inovative Approach of Informal Physics Teaching for High School Students. (Spanish Title: Inclusión de Temas Astronómicos en Uma Abordaje Innovadora de la Enseñanza Informal de Física Para Estudiantes de Secumdaria.) Inclusão de Temas Astronômicos Numa Abordagem Inovadora do Ensino Informal de Física Para Estudantes do Ensino Médio

    NASA Astrophysics Data System (ADS)

    Tiara Mota, Aline; de Morais Bonomini, Iracema Ariel; Meloni Martins Rosado, Ricardo

    2009-12-01

    The current work reports on an experience on Astronomy education at the Federal University of Itajubá through an extra-curricular course offered for High School students. This initiative was motivated by the low attention paid to the Astronomy subjects at this stage of the Brazilian Formal Education, in spite that the National Curricular Parameters (PCN and PCN+, in Brazil) point out the importance of their inclusion Este artículo relata una experiencia en la enseñanza de la astronomía efectuada en la Universidad Federal de Itajubá en la forma de un curso de extensión orientado para los estudiantes del colegio secundario. Esta iniciativa surgió de constatar la poca atención dada a la Astronomía en esta etapa de la Educación formal brasileña, a pesar que los Parámetros Curriculares Nacionales (PCN y PCN+, en Brasil) destacan la importancia de su inclusión. Este artigo relata uma experiência em ensino de Astronomia realizada na Universidade Federal de Itajubá na forma de um curso de extensão voltado para alunos do Ensino Médio. Esta iniciativa surgiu da pouca atenção que se dá à Astronomia nesta etapa da Educação embora os Parâmetros Curriculares Nacionais (PCN e PCN+) apontem a importância de sua inclusão.

  3. Recent results and prospects for NA62 experiment

    NASA Astrophysics Data System (ADS)

    Martellotti, Silvia; Aglieri Rinella, G.; Aliberti, R.; Ambrosino, F.; Ammendola, R.; Angelucci, B.; Antonelli, A.; Anzivino, G.; Arcidiacono, R.; Azhinenko, I.; Balev, S.; Barbanera, M.; Bendotti, J.; Biagioni, A.; Bician, L.; Biino, C.; Bizzeti, A.; Blazek, T.; Blik, A.; Bloch-Devaux, B.; Bolotov, V.; Bonaiuto, V.; Boretto, M.; Bragadireanu, M.; Britton, D.; Britvich, G.; Brunetti, M. B.; Bryman, D.; Bucci, F.; Butin, F.; Capitolo, E.; Capoccia, C.; Capussela, T.; Cassese, A.; Catinaccio, A.; Cecchetti, A.; Ceccucci, A.; Cenci, P.; Cerny, V.; Cerri, C.; Checcucci, B.; Chikilev, O.; Chiozzi, S.; Ciaranfi, R.; Collazuol, G.; Conovaloff, A.; Cooke, P.; Cooper, P.; Corradi, G.; Cortina Gil, E.; Costantini, F.; Cotorobai, F.; Cotta Ramusino, A.; Coward, D.; D'Agostini, G.; Dainton, J.; Dalpiaz, P.; Danielsson, H.; Degrange, J.; De Simone, N.; Di Filippo, D.; Di Lella, L.; Di Lorenzo, S.; Dixon, N.; Doble, N.; Dobrich, B.; Duk, V.; Elsha, V.; Engelfried, J.; Enik, T.; Estrada, N.; Falaleev, V.; Fantechi, R.; Fascianelli, V.; Federici, L.; Fedotov, S.; Fiorini, M.; Fry, J.; Fu, J.; Fucci, A.; Fulton, L.; Gallorini, S.; Galeotti, S.; Gamberini, E.; Gatignon, L.; Georgiev, G.; Gianoli, A.; Giorgi, M.; Giudici, S.; Glonti, L.; Goncalves Martins, A.; Gonnella, F.; Goudzovski, E.; Guida, R.; Gushchin, E.; Hahn, F.; Hallgren, B.; Heath, H.; Herman, F.; Husek, T.; Hutanu, O.; Hutchcroft, D.; Iacobuzio, L.; Iacopini, E.; Imbergamo, E.; Jamet, O.; Jarron, P.; Jones, E.; Kampf, K.; Kaplon, J.; Kekelidze, V.; Kholodenko, S.; Khoriauli, G.; Khotyantsev, A.; Khudyakov, A.; Kiryushin, Yu.; Kleimenova, A.; Kleinknecht, K.; Kluge, A.; Koval, M.; Kozhuharov, V.; Krivda, M.; Kucerova, Z.; Kudenko, Y.; Kunze, J.; Lamanna, G.; Latino, G.; Lazzeroni, C.; Lehmann-Miotto, G.; Lenci, R.; Lenti, M.; Leonardi, E.; Lichard, P.; Lietava, R.; Litov, L.; Lollini, R.; Lomidze, D.; Lonardo, A.; Lupi, M.; Lurkin, N.; McCormick, K.; Madigozhin, D.; Maire, G.; Mandeiro, C.; Mannelli, I.; Mannocchi, G.; Mapelli, A.; Marchetto, F.; Marchevski, R.; Martellotti, S.; Massarotti, P.; Massri, K.; Matak, P.; Maurice, E.; Mefodev, A.; Menichetti, E.; Minucci, E.; Mirra, M.; Misheva, M.; Molokanova, N.; Morant, J.; Morel, M.; Moulson, M.; Movchan, S.; Munday, D.; Napolitano, M.; Neri, I.; Newson, F.; Norton, A.; Noy, M.; Nuessle, G.; Numao, T.; Obraztsov, V.; Ostankov, A.; Padolski, S.; Page, R.; Palladino, V.; Paoluzzi, G.; Parkinson, C.; Pedreschi, E.; Pepe, M.; Perez Gomez, F.; Perrin-Terrin, M.; Peruzzo, L.; Petrov, P.; Petrucci, F.; Piandani, R.; Piccini, M.; Pietreanu, D.; Pinzino, J.; Polenkevich, I.; Pontisso, L.; Potrebenikov, Yu.; Protopopescu, D.; Raffaelli, F.; Raggi, M.; Riedler, P.; Romano, A.; Rubin, P.; Ruggiero, G.; Russo, V.; Ryjov, V.; Salamon, A.; Salina, G.; Samsonov, V.; Santoni, C.; Saracino, G.; Sargeni, F.; Semenov, V.; Sergi, A.; Serra, M.; Shaikhiev, A.; Shkarovskiy, S.; Skillicorn, I.; Soldi, D.; Sotnikov, A.; Sougonyaev, V.; Sozzi, M.; Spadaro, T.; Spinella, F.; Staley, R.; Sturgess, A.; Sutcliffe, P.; Szilasi, N.; Tagnani, D.; Trilov, S.; Valdata-Nappi, M.; Valente, P.; Vasile, M.; Vassilieva, T.; Velghe, B.; Veltri, M.; Venditti, S.; Vicini, P.; Volpe, R.; Vormstein, M.; Wahl, H.; Wanke, R.; Wertelaers, P.; Winhart, A.; Winston, R.; Wrona, B.; Yushchenko, O.; Zamkovsky, M.; Zinchenko, A.; NA62 Collaboration

    2017-04-01

    The K+ →π+ ν ν ‾ decay is theoretically one of the cleanest meson decays and so a good place to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is designed to measure the branching ratio of this decay with 10% precision. NA62 was commissioned in October 2014, took data in pilot runs in 2014 and 2015. The NA62 experimental setup is illustrated and data quality is reported.

  4. Origin of high Coulombic loss during sodiation in Na-Sn battery

    NASA Astrophysics Data System (ADS)

    Byeon, Young-Woon; Choi, Yong-Seok; Ahn, Jae-Pyoung; Lee, Jae-Chul

    2017-03-01

    Electrochemical sodiation is performed in crystalline Sn foil using in situ scanning electron microscopy (SEM) to simultaneously measure the changes in the electrical resistivity and volume of the Sn anode in a Na-Sn battery. We observe that sodiation causes an increase in the Sn anode resistivity by six orders of magnitude. Ab initio molecular dynamics simulations of the Na-Sn alloy system demonstrate that the increased resistivity of the anode is caused by the formation of an electrically resistive amorphous NaSn phase (a-NaSn) with a pseudogap. It is also observed that the formation of a-NaSn is always accompanied by a large volume expansion of ∼200%, causing the development of residual tensile stress. The residual stress in turn alters the electronic structure of the a-NaSn phase, further increasing the resistivity of a-NaSn and thus decreasing the energy efficiency of the Na-Sn battery.

  5. Mutant N143P Reveals How Na[superscript +] Activates Thrombin

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Niu, Weiling; Chen, Zhiwei; Bush-Pelc, Leslie A.

    2010-01-12

    The molecular mechanism of thrombin activation by Na{sup +} remains elusive. Its kinetic formulation requires extension of the classical Botts-Morales theory for the action of a modifier on an enzyme to correctly account for the contribution of the E*, E, and E:Na{sup +} forms. The extended scheme establishes that analysis of k{sub cat} unequivocally identifies allosteric transduction of Na{sup +} binding into enhanced catalytic activity. The thrombin mutant N143P features no Na{sup +}-dependent enhancement of k{sub cat} yet binds Na{sup +} with an affinity comparable to that of wild type. Crystal structures of the mutant in the presence and absencemore » of Na{sup +} confirm that Pro{sup 143} abrogates the important H-bond between the backbone N atom of residue 143 and the carbonyl O atom of Glu{sup 192}, which in turn controls the orientation of the Glu{sup 192}-Gly{sup 193} peptide bond and the correct architecture of the oxyanion hole. We conclude that Na{sup +} activates thrombin by securing the correct orientation of the Glu{sup 192}-Gly{sup 193} peptide bond, which is likely flipped in the absence of cation. Absolute conservation of the 143-192 H-bond in trypsin-like proteases and the importance of the oxyanion hole in protease function suggest that this mechanism of Na{sup +} activation is present in all Na{sup +}-activated trypsin-like proteases.« less

  6. 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.

  7. Spray-dried chitosan/acid/NaCl microparticles enhance saltiness perception.

    PubMed

    Yi, Cheng; Tsai, Min-Lang; Liu, Tristan

    2017-09-15

    The composition, physicochemical properties and salinity of spray-dried chitosan/acid/NaCl microparticles were tested to ensure a low-sodium and high-salinity salty agent. The spray-dried chitosan/acid/NaCl microparticles were hollow and had a favourable hygroscopicity, and increased NaCl content and decreased organic acid content. Their size of the microparticles was 15.4-32.0μm and increased with NaCl concentration. The microparticles of acetic and lactic acid groups had a NaCl crystal size of 1-2 and 1-4μm, respectively. The NaCl crystals of acetic, lactic and citric acid group microparticles were distributed on the microparticle matrices, mostly on the microparticle surface and mainly on the inner walls of the microparticles walls, respectively. The acetic and lactic acid group microparticles were relatively smaller than general salt, with NaCl crystals distributed on the particle surfaces. Consequently, they were perceived as saltier than general salt and could potentially be regarded as a low-sodium salt for surface-salted foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. β decay of Na32

    NASA Astrophysics Data System (ADS)

    Mattoon, C. M.; Sarazin, F.; Hackman, G.; Cunningham, E. S.; Austin, R. A. E.; Ball, G. C.; Chakrawarthy, R. S.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hyland, B.; Koopmans, K. A.; Leslie, J. R.; Phillips, A. A.; Schumaker, M. A.; Scraggs, H. C.; Schwarzenberg, J.; Smith, M. B.; Svensson, C. E.; Waddington, J. C.; Walker, P. M.; Washbrook, B.; Zganjar, E.

    2007-01-01

    The β-decay of Na32 has been studied using β-γ coincidences. New transitions and levels are tentatively placed in the level scheme of Mg32 from an analysis of γ-γ and β-γ-γ coincidences. The observation of the indirect feeding of the 2321 keV state in Mg32 removes some restrictions previously placed on the spin assignment for this state. No evidence of a state at 2117 keV in Mg32 is found. Previously unobserved weak transitions up to 5.4 MeV were recorded but could not be placed in the decay scheme of Na32.

  9. Effect of Na+ on surface fractal dimension of compacted bentonite

    NASA Astrophysics Data System (ADS)

    Xiang, G. S.; Xu, Y. F.; Jiang, H.

    2015-05-01

    Compacted Tsukinuno bentonite was immersed into NaCl solutions of different concentrations in oedometers, and the surface fractal dimension of bentonite-saline association was measured by nitrogen adsorption isotherms. The application of the Frenkel-Halsey-Hill equation and the Neimark thermodynamic method to nitrogen adsorption isotherms indicated that the surface roughness was greater for the bentonite-saline association. The surface fractal dimension of bentonite increased in the NaCl solution with low Na+ concentration, but decreased at high Na+ concentration. This process was accompanied by the same tendency in specific surface area and microporosity with the presence of Na+ coating in the clay particles.

  10. CYP96T1 of Narcissus sp. aff. pseudonarcissus Catalyzes Formation of the Para-Para' C-C Phenol Couple in the Amaryllidaceae Alkaloids

    PubMed Central

    Kilgore, Matthew B.; Augustin, Megan M.; May, Gregory D.; Crow, John A.; Kutchan, Toni M.

    2016-01-01

    The Amaryllidaceae alkaloids are a family of amino acid derived alkaloids with many biological activities; examples include haemanthamine, haemanthidine, galanthamine, lycorine, and maritidine. Central to the biosynthesis of the majority of these alkaloids is a C-C phenol-coupling reaction that can have para-para', para-ortho', or ortho-para' regiospecificity. Through comparative transcriptomics of Narcissus sp. aff. pseudonarcissus, Galanthus sp., and Galanthus elwesii we have identified a para-para' C-C phenol coupling cytochrome P450, CYP96T1, capable of forming the products (10bR,4aS)-noroxomaritidine and (10bS,4aR)-noroxomaritidine from 4′-O-methylnorbelladine. CYP96T1 was also shown to catalyzed formation of the para-ortho' phenol coupled product, N-demethylnarwedine, as less than 1% of the total product. CYP96T1 co-expresses with the previously characterized norbelladine 4′-O-methyltransferase. The discovery of CYP96T1 is of special interest because it catalyzes the first major branch in Amaryllidaceae alkaloid biosynthesis. CYP96T1 is also the first phenol-coupling enzyme characterized from a monocot. PMID:26941773

  11. Naïve Bayes classification in R.

    PubMed

    Zhang, Zhongheng

    2016-06-01

    Naïve Bayes classification is a kind of simple probabilistic classification methods based on Bayes' theorem with the assumption of independence between features. The model is trained on training dataset to make predictions by predict() function. This article introduces two functions naiveBayes() and train() for the performance of Naïve Bayes classification.

  12. Arrhenius Behavior of the Bulk Na-Ion Conductivity in Na3Sc2(PO4)3 Single Crystals Observed by Microcontact Impedance Spectroscopy.

    PubMed

    Rettenwander, Daniel; Redhammer, Günther J; Guin, Marie; Benisek, Artur; Krüger, Hannes; Guillon, Olivier; Wilkening, Martin; Tietz, Frank; Fleig, Jürgen

    2018-03-13

    NASICON-based solid electrolytes with exceptionally high Na-ion conductivities are considered to enable future all solid-state Na-ion battery technologies. Despite 40 years of research the interrelation between crystal structure and Na-ion conduction is still controversially discussed and far from being fully understood. In this study, microcontact impedance spectroscopy combined with single crystal X-ray diffraction, and differential scanning calorimetry is applied to tackle the question how bulk Na-ion conductivity σ bulk of sub-mm-sized flux grown Na 3 Sc 2 (PO 4 ) 3 (NSP) single crystals is influenced by supposed phase changes (α, β, and γ phase) discussed in literature. Although we found a smooth structural change at around 140 °C, which we assign to the β → γ phase transition, our conductivity data follow a single Arrhenius law from room temperature (RT) up to 220 °C. Obviously, the structural change, being mainly related to decreasing Na-ion ordering with increasing temperature, does not cause any jumps in Na-ion conductivity or any discontinuities in activation energies E a . Bulk ion dynamics in NSP have so far rarely been documented; here, under ambient conditions, σ bulk turned out to be as high as 3 × 10 -4 S cm -1  at RT ( E a, bulk = 0.39 eV) when directly measured with microcontacts for individual small single crystals.

  13. Arrhenius Behavior of the Bulk Na-Ion Conductivity in Na3Sc2(PO4)3 Single Crystals Observed by Microcontact Impedance Spectroscopy

    PubMed Central

    2018-01-01

    NASICON-based solid electrolytes with exceptionally high Na-ion conductivities are considered to enable future all solid-state Na-ion battery technologies. Despite 40 years of research the interrelation between crystal structure and Na-ion conduction is still controversially discussed and far from being fully understood. In this study, microcontact impedance spectroscopy combined with single crystal X-ray diffraction, and differential scanning calorimetry is applied to tackle the question how bulk Na-ion conductivity σbulk of sub-mm-sized flux grown Na3Sc2(PO4)3 (NSP) single crystals is influenced by supposed phase changes (α, β, and γ phase) discussed in literature. Although we found a smooth structural change at around 140 °C, which we assign to the β → γ phase transition, our conductivity data follow a single Arrhenius law from room temperature (RT) up to 220 °C. Obviously, the structural change, being mainly related to decreasing Na-ion ordering with increasing temperature, does not cause any jumps in Na-ion conductivity or any discontinuities in activation energies Ea. Bulk ion dynamics in NSP have so far rarely been documented; here, under ambient conditions, σbulk turned out to be as high as 3 × 10–4 S cm–1 at RT (Ea, bulk = 0.39 eV) when directly measured with microcontacts for individual small single crystals. PMID:29606799

  14. Diffusion and the dynamics of displacive phase transitions in cryolite (Na3AlF6) and chiolite (Na5Al3F14): Multi-nuclear NMR studies

    NASA Astrophysics Data System (ADS)

    Spearing, Dane R.; Stebbins, Jonathan F.; Farnan, Ian

    1994-10-01

    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 a better understanding of the atomic motions associated with the phase transition in cryolite, and Na diffusion in cryolite and chiolite. 27Al, 23Na, and 19F static NMR spectra and T1's in cryolite suggest that oscillatory motions of the [AlF6] octahedra among four micro-twin and anti-phase domains in α-cryolite begin at least 150° C below the transition temperature and persist above it. Variable temperature 23Na MAS NMR further indicates diffusional exchange at a rate of at least 13 kHz between the Na sites by the time the transition temperature is reached. 27Al and 23Na T1's show the same behavior with increasing temperature, indicating the same relaxation mechanisms are responsible for both. The first order nature of the cryolite transition is apparent as a jump in the 23Na and 27Al T1's. Above the transition temperature, the T1's decrease slightly indicating that the motions responsible for the drop in T1, are still present above the transition, further supporting the dynamic nature of the high temperature phase of cryolite. Chiolite 23Na static spectra decrease in linewidth with increasing temperature, indicating increased Na diffusion, which is interpreted as occurring within the [NaF6] sheets in the chiolite structure, but not between the two different Na sites. 27Al and 23Na T1's show similar behavior as in cryolite, but there is no discontinuity due to a phase transition. 19F T1's are constant from room temperature to 150° C indicating no oscillatory motion of the [AlF6] octahedra in chiolite.

  15. A dual-stage sodium thermal electrochemical converter (Na-TEC)

    NASA Astrophysics Data System (ADS)

    Limia, Alexander; Ha, Jong Min; Kottke, Peter; Gunawan, Andrey; Fedorov, Andrei G.; Lee, Seung Woo; Yee, Shannon K.

    2017-12-01

    The sodium thermal electrochemical converter (Na-TEC) is a heat engine that generates electricity through the isothermal expansion of sodium ions. The Na-TEC is a closed system that can theoretically achieve conversion efficiencies above 45% when operating between thermal reservoirs at 1150 K and 550 K. However, thermal designs have confined previous single-stage devices to thermal efficiencies below 20%. To mitigate some of these limitations, we consider dividing the isothermal expansion into two stages; one at the evaporator temperature (1150 K) and another at an intermediate temperature (650 K-1050 K). This dual-stage Na-TEC takes advantage of regeneration and reheating, and could be amenable to better thermal management. Herein, we demonstrate how the dual-stage device can improve the efficiency by up to 8% points over the best performing single-stage device. We also establish an application regime map for the single- and dual-stage Na-TEC in terms of the power density and the total thermal parasitic loss. Generally, a single-stage Na-TEC should be used for applications requiring high power densities, whereas a dual-stage Na-TEC should be used for applications requiring high efficiency.

  16. The enhancement of neutral metal Na layer above thunderstorms

    NASA Astrophysics Data System (ADS)

    Yu, Bingkun; Xue, Xianghui; Lu, Gaopeng; Kuo, Chengling; Dou, Xiankang; Gao, Qi; Qie, Xiushu; Wu, Jianfei; Tang, Yihuan

    2017-04-01

    Na (sodium) exists as layers of atoms in the mesosphere/lower thermosphere (MLT) at altitudes between 80 and 105 km. It has lower ionization potential of 5.139 eV than atmospheric species, such as O2 (12.06 eV). Tropospheric thunderstorms affect the lower ionosphere and the ionospheric sporadic E (Es) at 100 km can also be influenced by lightning. The mechanism is expected to be associated with transient luminous events (TLE) as red sprites and gigantic jets at upper atmosphere. However, measurements of ionospheric electric fields of 20mV·m-1 above thunderstorms are less than estimated value (>48 0mV·m-1) to excite ionization in the lower ionosphere. We found an enhancement of Na layer above thunderstorms. The increase of Na density in the statistical result can be as much as 500 cm-3 and it will have an impact on ionospheric chemistry and modify the conductivity properties of the MLT region. The ionospheric observations made with two digisondes near the Na lidar, the thunderstorm model, ionosphere model, and Na chemistry model are all used to discuss the possible mechanisms responsible for the enhancement of Na layer after thunderstorms.

  17. Na+-H+ exchange activity in taste receptor cells.

    PubMed

    Vinnikova, Anna K; Alam, Rammy I; Malik, Shahbaz A; Ereso, Glenn L; Feldman, George M; McCarty, John M; Knepper, Mark A; Heck, Gerard L; DeSimone, John A; Lyall, Vijay

    2004-03-01

    mRNA for two Na(+)-H(+)-exchanger isoforms 1 and 3 (NHE-1 and NHE-3) was detected by RT-PCR in fungiform and circumvallate taste receptor cells (TRCs). Anti-NHE-1 antibody binding was localized to the basolateral membranes, and the anti-NHE-3 antibody was localized in the apical membranes of fungiform and circumvallate TRCs. In a subset of TRCs, NHE-3 immunoreactivity was also detected in the intracellular compartment. For functional studies, an isolated lingual epithelium containing a single fungiform papilla was mounted with apical and basolateral sides isolated and perfused with nominally CO(2)/HCO(3)(-)-free physiological media (pH 7.4). The TRCs were monitored for changes in intracellular pH (pH(i)) and Na(+) ([Na(+)](i)) using fluorescence ratio imaging. At constant external pH, 1) removal of basolateral Na(+) reversibly decreased pH(i) and [Na(+)](i); 2) HOE642, a specific blocker, and amiloride, a nonspecific blocker of basolateral NHE-1, attenuated the decrease in pH(i) and [Na(+)](i); 3) exposure of TRCs to basolateral NH(4)Cl or sodium acetate pulses induced transient decreases in pH(i) that recovered spontaneously to baseline; 4) pH(i) recovery was inhibited by basolateral amiloride, 5-(N-methyl-N-isobutyl)-amiloride (MIA), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), HOE642, and by Na(+) removal; 5) HOE642, MIA, EIPA, and amiloride inhibited pH(i) recovery with K(i) values of 0.23, 0.46, 0.84, and 29 microM, respectively; and 6) a decrease in apical or basolateral pH acidified TRC pH(i) and inhibited spontaneous pH(i) recovery. The results indicate the presence of a functional NHE-1 in the basolateral membranes of TRCs. We hypothesize that NHE-1 is involved in sour taste transduction since its activity is modulated during acid stimulation.

  18. 3 Tesla 23Na Magnetic Resonance Imaging During Acute Kidney Injury.

    PubMed

    Hammon, Matthias; Grossmann, Susan; Linz, Peter; Seuss, Hannes; Hammon, Rebecca; Rosenhauer, Daniela; Janka, Rolf; Cavallaro, Alexander; Luft, Friedrich C; Titze, Jens; Uder, Michael; Dahlmann, Anke

    2017-09-01

    Sodium and proton magnetic resonance imaging ( 23 Na/ 1 H-MRI) have shown that muscle and skin can store Na + without water. In chronic renal failure and in heart failure, Na + mobilization occurs, but is variable depending on age, dialysis vintage, and other features. Na + storage depots have not been studied in patients with acute kidney injury (AKI). We studied 7 patients with AKI (mean age: 51.7 years; range: 25-84) and 14 age-matched and gender-matched healthy controls. All underwent 23 Na/ 1 H-MRI at the calf. Patients were studied before and after acute hemodialysis therapy within 5-6 days. The 23 Na-MRI produced grayscale images containing Na + phantoms, which served to quantify Na + contents. A fat-suppressed inversion recovery sequence was used to quantify H 2 O content. Plasma Na + levels did not change. Mean Na + contents in muscle and skin did not significantly change following four to five cycles of hemodialysis treatment (before therapy: 32.7 ± 6.9 and 44.2 ± 13.5 mmol/L, respectively; after dialysis: 31.7 ± 10.2 and 42.8 ± 11.8 mmol/L, respectively; P > .05). Water content measurements did not differ significantly before and after hemodialysis in muscle and skin (P > .05). Na + contents in calf muscle and skin of patients before hemodialysis were significantly higher than in healthy subjects (16.6 ± 2.1 and 17.9 ± 3.2) and remained significantly elevated after hemodialysis. Na + in muscle and skin accumulates in patients with AKI and, in contrast to patients receiving chronic hemodialysis and those with acute heart failure, is not mobilized with hemodialysis within 5-6 days. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  19. Na+ extrusion from the cytosol and tissue-specific Na+ sequestration in roots confer differential salt stress tolerance between durum and bread wheat.

    PubMed

    Wu, Honghong; Shabala, Lana; Azzarello, Elisa; Huang, Yuqing; Pandolfi, Camilla; Su, Nana; Wu, Qi; Cai, Shengguan; Bazihizina, Nadia; Wang, Lu; Zhou, Meixue; Mancuso, Stefano; Chen, Zhonghua; Shabala, Sergey

    2018-06-11

    The progress in plant breeding for salinity stress tolerance is handicapped by the lack of understanding of the specificity of salt stress signalling and adaptation at the cellular and tissue levels. In this study, we used electrophysiological, fluorescence imaging, and real-time quantitative PCR tools to elucidate the essentiality of the cytosolic Na+ extrusion in functionally different root zones (elongation, meristem, and mature) in a large number of bread and durum wheat accessions. We show that the difference in the root's ability for vacuolar Na+ sequestration in the mature zone may explain differential salinity stress tolerance between salt-sensitive durum and salt-tolerant bread wheat species. Bread wheat genotypes also had on average 30% higher capacity for net Na+ efflux from the root elongation zone, providing the first direct evidence for the essentiality of the root salt exclusion trait at the cellular level. At the same time, cytosolic Na+ accumulation in the root meristem was significantly higher in bread wheat, leading to the suggestion that this tissue may harbour a putative salt sensor. This hypothesis was then tested by investigating patterns of Na+ distribution and the relative expression level of several key genes related to Na+ transport in leaves in plants with intact roots and in those in which the root meristems were removed. We show that tampering with this sensing mechanism has resulted in a salt-sensitive phenotype, largely due to compromising the plant's ability to sequester Na+ in mesophyll cell vacuoles. The implications of these findings for plant breeding for salinity stress tolerance are discussed.

  20. OsHKT1;4-mediated Na(+) transport in stems contributes to Na(+) exclusion from leaf blades of rice at the reproductive growth stage upon salt stress.

    PubMed

    Suzuki, Kei; Yamaji, Naoki; Costa, Alex; Okuma, Eiji; Kobayashi, Natsuko I; Kashiwagi, Tatsuhiko; Katsuhara, Maki; Wang, Cun; Tanoi, Keitaro; Murata, Yoshiyuki; Schroeder, Julian I; Ma, Jian Feng; Horie, Tomoaki

    2016-01-19

    Na(+) exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K(+) transporter (HKT) family have been demonstrated to mediate leaf blade-Na(+) exclusion upon salinity stress via Na(+)-selective transport. Multiple HKT1 transporters are known to function in rice (Oryza sativa). However, the ion transport function of OsHKT1;4 and its contribution to the Na(+) exclusion mechanism in rice remain to be elucidated. Here, we report results of the functional characterization of the OsHKT1;4 transporter in rice. OsHKT1;4 mediated robust Na(+) transport in Saccharomyces cerevisiae and Xenopus laevis oocytes. Electrophysiological experiments demonstrated that OsHKT1;4 shows strong Na(+) selectivity among cations tested, including Li(+), Na(+), K(+), Rb(+), Cs(+), and NH4 (+), in oocytes. A chimeric protein, EGFP-OsHKT1;4, was found to be functional in oocytes and targeted to the plasma membrane of rice protoplasts. The level of OsHKT1;4 transcripts was prominent in leaf sheaths throughout the growth stages. Unexpectedly however, we demonstrate here accumulation of OsHKT1;4 transcripts in the stem including internode II and peduncle in the reproductive growth stage. Moreover, phenotypic analysis of OsHKT1;4 RNAi plants in the vegetative growth stage revealed no profound influence on the growth and ion accumulation in comparison with WT plants upon salinity stress. However, imposition of salinity stress on the RNAi plants in the reproductive growth stage caused significant Na(+) overaccumulation in aerial organs, in particular, leaf blades and sheaths. In addition, (22)Na(+) tracer experiments using peduncles of RNAi and WT plants suggested xylem Na(+) unloading by OsHKT1;4. Taken together, our results indicate a newly recognized function of OsHKT1;4 in Na(+) exclusion in stems together with leaf sheaths, thus excluding Na(+) from leaf blades of a japonica rice cultivar in the

  1. Reduced expression of Na(v)1.6 sodium channels and compensation by Na(v)1.2 channels in mice heterozygous for a null mutation in Scn8a.

    PubMed

    Vega, Ana V; Henry, Diane L; Matthews, Gary

    2008-09-05

    The voltage-gated sodium channel alpha subunit Na(v)1.6, encoded by the Scn8a gene, accumulates at high density at mature nodes of Ranvier of myelinated axons, replacing the Na(v)1.2 channels found at nodes earlier in development. To investigate this preferential expression of Na(v)1.6 at adult nodes, we examined isoform-specific expression of sodium channels in mice heterozygous for a null mutation in Scn8a. Immunoblots from these +/- mice had 50% of the wild-type level of Na(v)1.6 protein, and their optic-nerve nodes of Ranvier had correspondingly less anti-Na(v)1.6 immunofluorescence. Protein level and nodal immunofluorescence of the Na(v)1.2 alpha subunit increased in Scn8a(+/-) mice, keeping total sodium channel expression approximately constant despite partial loss of Na(v)1.6 channels. The results are consistent with a model in which Na(v)1.6 and Na(v)1.2 compete for binding partners at sites of high channel density, such as nodes of Ranvier. We suggest that Na(v)1.6 channels normally occupy most of the molecular machinery responsible for channel clustering because they have higher binding affinity, and not because they are exclusively recognized by mechanisms for transport and insertion of sodium channels in myelinated axons. The reduced amount of Na(v)1.6 protein in Scn8a(+/-) mice is apparently insufficient to saturate the nodal binding sites, allowing Na(v)1.2 channels to compete more successfully.

  2. Mechanism of potassium ion uptake by the Na+/K+-ATPase

    PubMed Central

    Castillo, Juan P.; Rui, Huan; Basilio, Daniel; Das, Avisek; Roux, Benoît; Latorre, Ramon; Bezanilla, Francisco; Holmgren, Miguel

    2015-01-01

    The Na+/K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As ions are transported, they become transiently trapped between intracellular and extracellular gates. Once the external gate opens, three Na+ ions are released, followed by the binding and occlusion of two K+ ions. While the mechanisms of Na+ release have been well characterized by the study of transient Na+ currents, smaller and faster transient currents mediated by external K+ have been more difficult to study. Here we show that external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Consistent with these results, molecular dynamics simulations of a pump model show a wide water-filled access channel connecting the binding site to the external solution. These results suggest a mechanism of K+ gating different from that of Na+ occlusion. PMID:26205423

  3. Hierarchical Porous Carbon Spheres for High-Performance Na-O2 Batteries.

    PubMed

    Sun, Bing; Kretschmer, Katja; Xie, Xiuqiang; Munroe, Paul; Peng, Zhangquan; Wang, Guoxiu

    2017-12-01

    As a new family member of room-temperature aprotic metal-O 2 batteries, Na-O 2 batteries, are attracting growing attention because of their relatively high theoretical specific energy and particularly their uncompromised round-trip efficiency. Here, a hierarchical porous carbon sphere (PCS) electrode that has outstanding properties to realize Na-O 2 batteries with excellent electrochemical performances is reported. The controlled porosity of the PCS electrode, with macropores formed between PCSs and nanopores inside each PCS, enables effective formation/decomposition of NaO 2 by facilitating the electrolyte impregnation and oxygen diffusion to the inner part of the oxygen electrode. In addition, the discharge product of NaO 2 is deposited on the surface of individual PCSs with an unusual conformal film-like morphology, which can be more easily decomposed than the commonly observed microsized NaO 2 cubes in Na-O 2 batteries. A combination of coulometry, X-ray diffraction, and in situ differential electrochemical mass spectrometry provides compelling evidence that the operation of the PCS-based Na-O 2 battery is underpinned by the formation and decomposition of NaO 2 . This work demonstrates that employing nanostructured carbon materials to control the porosity, pore-size distribution of the oxygen electrodes, and the morphology of the discharged NaO 2 is a promising strategy to develop high-performance Na-O 2 batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Cooling by Para-to-Ortho-Hydrogen Conversion

    NASA Technical Reports Server (NTRS)

    Sherman, A.; Nast, T.

    1983-01-01

    Catalyst speeds conversion, increasing capacity of solid hydrogen cooling system. In radial-flow catalytic converter, para-hydrogen is converted to equilibrium mixture of para-hydrogen and ortho-hydrogen as it passes through porous cylinder of catalyst. Addition of catalyst increases capacity of hydrogen sublimation cooling systems for radiation detectors.

  5. 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

  6. NaCl responsive taste cells in the mouse fungiform taste buds.

    PubMed

    Yoshida, R; Horio, N; Murata, Y; Yasumatsu, K; Shigemura, N; Ninomiya, Y

    2009-03-17

    Previous studies have demonstrated that rodents' chorda tympani (CT) nerve fibers responding to NaCl can be classified according to their sensitivities to the epithelial sodium channel (ENaC) blocker amiloride into two groups: amiloride-sensitive (AS) and -insensitive (AI). The AS fibers were shown to respond specifically to NaCl, whereas AI fibers broadly respond to various electrolytes, including NaCl. These data suggest that salt taste transduction in taste cells may be composed of at least two different systems; AS and AI ones. To further address this issue, we investigated the responses to NaCl, KCl and HCl and the amiloride sensitivity of mouse fungiform papilla taste bud cells which are innervated by the CT nerve. Comparable with the CT data, the results indicated that 56 NaCl-responsive cells tested were classified into two groups; 25 cells ( approximately 44%) narrowly responded to NaCl and their NaCl response were inhibited by amiloride (AS cells), whereas the remaining 31 cells ( approximately 56%) responded not only to NaCl, but to KCl and/or HCl and showed no amiloride inhibition of NaCl responses (AI cells). Amiloride applied to the basolateral side of taste cells had no effect on NaCl responses in the AS and AI cells. Single cell reverse transcription-polymerase chain reaction (RT-PCR) experiments indicated that ENaC subunit mRNA was expressed in a subset of AS cells. These findings suggest that the mouse fungiform taste bud is composed of AS and AI cells that can transmit taste information differently to their corresponding types of CT fibers, and apical ENaCs may be involved in the NaCl responses of AS cells.

  7. Selective inhibition of K(+)-stimulation of Na,K-ATPase by bretylium.

    PubMed Central

    Tiku, P. E.; Nowell, P. T.

    1991-01-01

    1. The effects of bretylium were investigated on purified Na,K-ATPase from guinea-pig heart and on the Na/K pump in trout erythrocytes, with a view to further identifying the mechanism(s) associated with its antiarrhythmic effects. 2. Na,K-ATPase activity of the thiocyanate-dispersed enzyme was determined by the measurement of inorganic phosphate produced by ATP hydrolysis. 3. When the concentrations of each of the Na,K-ATPase activating components were varied in turn, bretylium (1-5 mmol l-1) exhibited competitive-type effects against K+ with a Ki of 1.4 mmol l-1 and noncompetitive-type effects against Na+, Mg2+ and ATP. 4. In K+ influx studies in trout erythrocytes with 86Rb+ used as the marker, the inhibition of total influx observed with bretylium (5 and 10 mmol l-1) was attributable to the bretylium cation selectively inhibiting the Na/K pump-mediated influx with the associated tosylate anion inhibiting Na/K cotransport. 5. The observed inhibition kinetics indicated that the bretylium cation (2-15 mmol l-1) competitively inhibited K+ stimulation of the Na/K pump at 6 and 1.25 mmol l-1 external K+ with a mean K1 of 2.3 mmol l-1. 6. The effects demonstrated on the functioning Na/K pump in erythrocytes confirmed the Na,K-ATPase findings, with bretylium selectively inhibiting K+ stimulation of the pump mechanism in both cases. 7. It is suggested that Na,K-ATPase inhibition may contribute to the antiarrhythmic and positive inotropic effects of bretylium with the cardiac accumulation of bretylium also possibly being a further important factor. PMID:1667290

  8. 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

  9. ParaChoice Model.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Heimer, Brandon Walter; Levinson, Rebecca Sobel; West, Todd H.

    Analysis with the ParaChoice model addresses three barriers from the VTO Multi-Year Program Plan: availability of alternative fuels and electric charging station infrastructure, availability of AFVs and electric drive vehicles, and consumer reluctance to purchase new technologies. In this fiscal year, we first examined the relationship between the availability of alternative fuels and station infrastructure. Specifically, we studied how electric vehicle charging infrastructure affects the ability of EVs to compete with vehicles that rely on mature, conventional petroleum-based fuels. Second, we studied how the availability of less costly AFVs promotes their representation in the LDV fleet. Third, we used ParaChoicemore » trade space analyses to help inform which consumers are reluctant to purchase new technologies. Last, we began analysis of impacts of alternative energy technologies on Class 8 trucks to isolate those that may most efficaciously advance HDV efficiency and petroleum use reduction goals.« less

  10. Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution

    PubMed Central

    Zhou, Aifen; Baidoo, Edward; He, Zhili; Mukhopadhyay, Aindrila; Baumohl, Jason K; Benke, Peter; Joachimiak, Marcin P; Xie, Ming; Song, Rong; Arkin, Adam P; Hazen, Terry C; Keasling, Jay D; Wall, Judy D; Stahl, David A; Zhou, Jizhong

    2013-01-01

    Desulfovibrio vulgaris Hildenborough strains with significantly increased tolerance to NaCl were obtained via experimental evolution. A NaCl-evolved strain, ES9-11, isolated from a population cultured for 1200 generations in medium amended with 100 mM NaCl, showed better tolerance to NaCl than a control strain, EC3-10, cultured for 1200 generations in parallel but without NaCl amendment in medium. To understand the NaCl adaptation mechanism in ES9-11, we analyzed the transcriptional, metabolite and phospholipid fatty acid (PLFA) profiles of strain ES9-11 with 0, 100- or 250 mM-added NaCl in medium compared with the ancestral strain and EC3-10 as controls. In all the culture conditions, increased expressions of genes involved in amino-acid synthesis and transport, energy production, cation efflux and decreased expression of flagellar assembly genes were detected in ES9-11. Consistently, increased abundances of organic solutes and decreased cell motility were observed in ES9-11. Glutamate appears to be the most important osmoprotectant in D. vulgaris under NaCl stress, whereas, other organic solutes such as glutamine, glycine and glycine betaine might contribute to NaCl tolerance under low NaCl concentration only. Unsaturation indices of PLFA significantly increased in ES9-11. Branched unsaturated PLFAs i17:1 ω9c, a17:1 ω9c and branched saturated i15:0 might have important roles in maintaining proper membrane fluidity under NaCl stress. Taken together, these data suggest that the accumulation of osmolytes, increased membrane fluidity, decreased cell motility and possibly an increased exclusion of Na+ contribute to increased NaCl tolerance in NaCl-evolved D. vulgaris. PMID:23575373

  11. Trisodium citrate, Na 3 (C 6 H 5 O 7 )

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rammohan, Alagappa; Kaduk, James A.

    2016-05-10

    The crystal structure of anhydrous trisodium citrate, Na 3(C 6H 5O 7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory (DFT). There are two independent five-coordinate Na +and one six-coordinate Na +cations in the asymmetric unit. The [NaO 5] and [NaO 6] polyhedra share edges and corners to form a three-dimensional framework. There are channels parallel to theaandbaxes in which the remainder of the citrate anions reside. The only hydrogen bonds are an intramolecular one between the hydroxy group and one of the terminal carboxylate O atoms and an intermolecular onemore » between a methylene group and the hydroxyl O atom.« less

  12. Investigation of the thermonuclear 18Ne(α,p)21Na reaction rate via resonant elastic scattering of 21Na + p

    NASA Astrophysics Data System (ADS)

    Zhang, L. Y.; He, J. J.; Parikh, A.; Xu, S. W.; Yamaguchi, H.; Kahl, D.; Kubono, S.; Mohr, P.; Hu, J.; Ma, P.; Chen, S. Z.; Wakabayashi, Y.; Wang, H. W.; Tian, W. D.; Chen, R. F.; Guo, B.; Hashimoto, T.; Togano, Y.; Hayakawa, S.; Teranishi, T.; Iwasa, N.; Yamada, T.; Komatsubara, T.; Zhang, Y. H.; Zhou, X. H.

    2014-01-01

    The 18Ne(α,p)21Na reaction is thought to be one of the key breakout reactions from the hot CNO cycles to the rp process in type I x-ray bursts. In this work, the resonant properties of the compound nucleus 22Mg have been investigated by measuring the resonant elastic scattering of 21Na + p. An 89-MeV 21Na radioactive beam delivered from the CNS Radioactive Ion Beam Separator bombarded an 8.8 mg/cm2 thick polyethylene (CH2)n target. The 21Na beam intensity was about 2×105 pps, with a purity of about 70% on target. The recoiled protons were measured at the center-of-mass scattering angles of θc.m.≈175.2∘, 152.2∘, and 150.5∘ by three sets of ΔE-E telescopes, respectively. The excitation function was obtained with the thick-target method over energies Ex(22Mg)=5.5-9.2 MeV. In total, 23 states above the proton-threshold in 22Mg were observed, and their resonant parameters were determined via an R-matrix analysis of the excitation functions. We have made several new Jπ assignments and confirmed some tentative assignments made in previous work. The thermonuclear 18Ne(α,p)21Na rate has been recalculated based on our recommended spin-parity assignments. The astrophysical impact of our new rate has been investigated through one-zone postprocessing x-ray burst calculations. We find that the 18Ne(α,p)21Na rate significantly affects the peak nuclear energy generation rate, reaction fluxes, and onset temperature of this breakout reaction in these astrophysical phenomena.

  13. Thermodynamic modeling of melts in the system Na 2O-NaAlO 2-SiO 2-F 2O -1

    NASA Astrophysics Data System (ADS)

    Dolejš, David; Baker, Don R.

    2005-12-01

    Fluorine is a common volatile element in magmatic-hydrothermal systems, but its solution mechanisms and thermodynamic description in highly polymerized silicate melts are poorly known. We have developed a thermodynamic model for fluorosilicate liquids that links experimentally determined phase equilibria and spectroscopic information on melt structure. The model is applicable to crystallization of fluoride minerals, fluoride-silicate immiscibility in natural felsic melts, and metallurgical processes. Configurational properties of fluorosilicate melts are described by mixing on three site levels (sublattices): (1) alkali fluoride, polyhedral aluminofluoride and silicofluoride species and nonbridging terminations of the aluminosilicate network, (2) alkali-aluminate and silicate tetrahedra within the network and (3) bridging oxygen, nonbridging oxygen and terminal fluorine atoms on tetrahedral apices of the network. Abundances of individual chemical species are described by a homogeneous equilibrium representing melt depolymerization: F - (free) + O 0 (bridging) = F 0 (terminal) + O - (nonbridging) which corresponds to a replacement of an oxygen bridging two tetrahedra by a pair of terminations, one with F and the other with an O and a charge-balancing Na. In cryolite-bearing systems two additional interaction mechanisms occur: (1) the self-dissociation of octahedral aluminofluoride complexes: [AlF 6] = [AlF 4] + 2 [F], and (2) the short-range order between (O,F)-corners and (Si,NaAl)-centers of tetrahedra: Si-O-Si + 2 [NaAl]-F = [NaAl]-O-[NaAl] + 2 Si-F. Portrayal of these equilibria in ternary Thompson reaction space allows for the decrease in the number of interaction mechanisms by linearly combining melt depolymerization with tetrahedral short-range order. In this formulation, the nonideal thermodynamic properties are represented by reaction energies of homogeneous equilibria, thus defining directly individual chemical species concentrations and configurational

  14. A Mechanism for Intracellular Release of Na+ by Neurotransmitter: Sodium Symporters

    PubMed Central

    Malinauskaite, Lina; Reinhard, Linda; Lyons, Joseph A.; Yano, Hideaki; Javitch, Jonathan A.

    2015-01-01

    Neurotransmitter:sodium symporters (NSS) terminate synaptic signal transmission by Na+-dependent reuptake of released neurotransmitters, with key conformational states reported for a bacterial homolog LeuT and an inhibitor-bound Drosophila dopamine transporter. However, a coherent mechanism of Na+-driven transport has not been described. Here, we present two crystal structures of MhsT, a NSS member from Bacillus halodurans, in occluded inward-facing states with bound Na+ ions and L-Trp that provide insight into the cytoplasmic release of Na+. The switch from outward- to inward-oriented states is centered on the partial unwinding of transmembrane helix 5, which is facilitated by a conserved GlyX9Pro motif that opens an intracellular pathway for water to access the Na2 site. Based on our structural and functional findings we propose a mechanism according to which solvation through the TM5 pathway facilitates Na+ release from Na2 and the transition to an inward-open state. PMID:25282149

  15. NOAA Weather Radio

    Science.gov Websites

    Search For Go NWS All NOAA NWR Recepción El área de la recepción nominal para un receptor de Radio cosas afectan la recepción de señas de la radio. Por ejemplo, las extensiones grandes de agua de sal de NWR. Siga leyendo si está dentro del área pero tiene dificultad con recepción. Su seña de la

  16. Hydrogeology and sustainable future groundwater abstraction from the Agua Verde aquifer in the Atacama Desert, northern Chile

    NASA Astrophysics Data System (ADS)

    Urrutia, Javier; Jódar, Jorge; Medina, Agustín; Herrera, Christian; Chong, Guillermo; Urqueta, Harry; Luque, José A.

    2018-03-01

    The hyper-arid conditions prevailing in Agua Verde aquifer in northern Chile make this system the most important water source for nearby towns and mining industries. Due to the growing demand for water in this region, recharge is investigated along with the impact of intense pumping activity in this aquifer. A conceptual model of the hydrogeological system is developed and implemented into a two-dimensional groundwater-flow numerical model. To assess the impact of climate change and groundwater extraction, several scenarios are simulated considering variations in both aquifer recharge and withdrawals. The estimated average groundwater lateral recharge from Precordillera (pre-mountain range) is about 4,482 m3/day. The scenarios that consider an increase of water withdrawal show a non-sustainable groundwater consumption leading to an over-exploitation of the resource, because the outflows surpasses inflows, causing storage depletion. The greater the depletion, the larger the impact of recharge reduction caused by the considered future climate change. This result indicates that the combined effects of such factors may have a severe impact on groundwater availability as found in other groundwater-dependent regions located in arid environments. Furthermore, the scenarios that consider a reduction of the extraction flow rate show that it may be possible to partially alleviate the damage already caused to the aquifer by the continuous extractions since 1974, and it can partially counteract climate change impacts on future groundwater availability caused by a decrease in precipitation (and so in recharge), if the desalination plant in Taltal increases its capacity.

  17. New-concept Batteries Based on Aqueous Li+/Na+ Mixed-ion Electrolytes

    PubMed Central

    Chen, Liang; Gu, Qingwen; Zhou, Xufeng; Lee, Saixi; Xia, Yonggao; Liu, Zhaoping

    2013-01-01

    Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li+/Na+ mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li+ insertion/extraction reaction, and the other mainly relates to Na+ extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg−1 and 25 Wh kg−1 based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li+ and Na+ due to its specific mechanism unlike the traditional “rocking-chair” lithium-ion batteries. Hence, the Li+/Na+ mixed-ion batteries offer promising applications in energy storage and Li+/Na+ separation. PMID:23736113

  18. Thermodynamic Model of the Na-Al-Si-O-F Melts

    NASA Astrophysics Data System (ADS)

    Dolejs, D.; Baker, D. R.

    2004-05-01

    Fluorine is a common volatile element in magmatic-hydrothermal systems, but its solution mechanisms in highly polymerized silicate melts are poorly known. We have developed a thermodynamic model for fluorosilicate liquids which links experimentally determined phase equilibria and spectroscopic information on melt structure. The model is applicable to crystallization of fluoride minerals or fluoride-silicate immiscibility in natural felsic melts. Configurational properties of the liquid are defined by mixing of alkali fluoride, polyhedral aluminofluoride and silicofluoride species and non-bridging terminations of the silicate network. Abundances of individual structural species are described by a homogeneous equilibrium, representing melt depolymerization: F- (free) + O0 (bridging) = F0 (terminal) + O- (non-bridging), which is a replacement of one oxygen bridge, Si-O-Si, by two terminations, Si-F | Na-O-Si. In cryolite-bearing systems, the self-dissociation of octahedral aluminofluoride complexes: Na3[AlF6] = Na[AlF4] + 2 NaF, and the short-range order between (O,F)-corners and (Si,NaAl)-centers of tetrahedra: Si-O-Si + 2 [NaAl]-F = [NaAl]-O-[NaAl] + 2 Si-F, represent two additional interaction mechanisms. Portrayal of these equilibria in ternary Thompson reaction space allows to decrease the number of interaction mechanisms by linearly combining melt depolymerization with tetrahedral short-range order. In this formulation, the interaction parameters are incorporated directly in configurational properties, thus the complete melt speciation can be calculated, and the activities of any macroscopic species are readily derived. The model has been applied to subsystems of the Na2O-NaAlO2-SiO2-F2O-1 compositional space. Activity-composition relationships in the villiaumite-sodium silicate binaries require clustering of silicate tetrahedra in fluoride solvent. Phase-equilibria in cryolite-nepheline and cryolite-albite systems illustrate an overall increase of Na3AlF6 self

  19. [Effect of NaOH-treatment on dry-thermophilic anaerobic digestion of Spartina alterniflora].

    PubMed

    Chen, Guang-Yin; Zheng, Zheng; Chang, Zhi-Zhou; Ye, Xiao-Mei; Luo, Yan

    2011-07-01

    In order to improve the biotransformation rate of lignocellulosic materials, sodium hydroxide (NaOH) was widely used to pretreat lignocellulosic materials. Effect of NaOH-treatment on dry-thermophilic anaerobic digestion of Spartina alternflora was studied by batch model under the temperature of 55 degrees C +/- 1 degrees C, at the initial total solid loading (TSL) of 20%. The results indicated that biogas production was inhibited by NaOH-treatment and improved by NaOH-treatment with water washed. The cumulative biogas yield of control (CK), NaOH-treated and NaOH-treated with water washed (NaOH + water) were 268.35 mL/g, 205.76 mL/g and 299.97 mL/g, respectively. The methane content of CK and NaOH + water treatments kept stable while fluctuation of NaOH-treated treatment during anaerobic digestion process was observed. Compared with CK and NaOH + water treatments, methane content of NaOH-treated treatment was improved by 5.30%. The content of hemi-cellulose and cellulose of S. alternifora decreased while content of lignin of S. alterniflora increased after 51-day anaerobic digestion. The crystallinity of cellulose of S. alterniflora increased after NaOH-treatment which was consistent to the result of FTIR. The lignocellulosic structure was destroyed and the biodegradability of S. alterniflora was increased by NaOH pretreatment. However, the amount of Na+ was taken into the anaerobic system, besides the high Na+ content in the plant itself which inhibited the anaerobic microorganisms. Therefore, NaOH-treatment is considered to be unsuitable for the anaerobic digestion of S. alterniflora.

  20. Highly conductive porous Na-embedded carbon nanowalls for high-performance capacitive deionization

    NASA Astrophysics Data System (ADS)

    Chang, Liang; Hu, Yun Hang

    2018-05-01

    Highly conductive porous Na-embedded carbon nanowalls (Na@C), which were recently invented, have exhibited excellent performance for dye-sensitized solar cells and electric double-layer capacitors. In this work, Na@C was demonstrated as an excellent electrode material for capacitive deionization (CDI). In a three-electrode configuration system, the specific capacity of the Na@C electrodes can achieve 306.4 F/g at current density of 0.2 A/g in 1 M NaCl, which is higher than that (235.2 F/g) of activated carbon (AC) electrodes. Furthermore, a high electrosorption capacity of 8.75 mg g-1 in 100 mg/L NaCl was obtained with the Na@C electrodes in a batch-mode capacitive deionization cell. It exceeds the electrosorption capacity (4.08 mg g-1) of AC electrodes. The Na@C electrode also showed a promising cycle stability. The excellent performance of Na@C electrode for capacitive deionization (CDI) can be attributed to its high electrical conductivity and large accessible surface area.

  1. Specialized Functional Diversity and Interactions of the Na,K-ATPase

    PubMed Central

    Matchkov, Vladimir V.; Krivoi, Igor I.

    2016-01-01

    Na,K-ATPase is a protein ubiquitously expressed in the plasma membrane of all animal cells and vitally essential for their functions. A specialized functional diversity of the Na,K-ATPase isozymes is provided by molecular heterogeneity, distinct subcellular localizations, and functional interactions with molecular environment. Studies over the last decades clearly demonstrated complex and isoform-specific reciprocal functional interactions between the Na,K-ATPase and neighboring proteins and lipids. These interactions are enabled by a spatially restricted ion homeostasis, direct protein-protein/lipid interactions, and protein kinase signaling pathways. In addition to its “classical” function in ion translocation, the Na,K-ATPase is now considered as one of the most important signaling molecules in neuronal, epithelial, skeletal, cardiac and vascular tissues. Accordingly, the Na,K-ATPase forms specialized sub-cellular multimolecular microdomains which act as receptors to circulating endogenous cardiotonic steroids (CTS) triggering a number of signaling pathways. Changes in these endogenous cardiotonic steroid levels and initiated signaling responses have significant adaptive values for tissues and whole organisms under numerous physiological and pathophysiological conditions. This review discusses recent progress in the studies of functional interactions between the Na,K-ATPase and molecular microenvironment, the Na,K-ATPase-dependent signaling pathways and their significance for diversity of cell function. PMID:27252653

  2. Experimental Studies of NaK in a Simulated Space Environment

    NASA Technical Reports Server (NTRS)

    Gibons, Marc; Sanzi, James; Ljubanovic, Damir

    2011-01-01

    Space fission power systems are being developed at the National Aeronautics and Space Administration (NASA) and Department of Energy (DOE) with a short term goal of building a full scale, non-nuclear, Technology Demonstration Unit (TDU) test at NASA's Glenn Research Center. Due to the geometric constraints, mass restrictions, and fairly high temperatures associated with space reactors, liquid metals are typically used as the primary coolant. A eutectic mixture of sodium (22 percent) and potassium (78 percent), or NaK, has been chosen as the coolant for the TDU with a total system capacity of approximately 55 L. NaK, like all alkali metals, is very reactive, and warrants certain safety considerations. To adequately examine the risk associated with the personnel, facility, and test hardware during a potential NaK leak in the large scale TDU test, a small scale experiment was performed in which NaK was released in a thermal vacuum chamber under controlled conditions. The study focused on detecting NaK leaks in the vacuum environment as well as the molecular flow of the NaK vapor. This paper reflects the work completed during the NaK experiment and provides results and discussion relative to the findings.

  3. Ordered and disordered polymorphs of Na(Ni 2/3Sb 1/3)O₂: Honeycomb-ordered cathodes for Na-ion batteries

    DOE PAGES

    Ma, Jeffrey; Wu, Lijun; Bo, Shou -Hang; ...

    2015-04-14

    Na-ion batteries are appealing alternatives to Li-ion battery systems for large-scale energy storage applications in which elemental cost and abundance are important. Although it is difficult to find Na-ion batteries which achieve substantial specific capacities at voltages above 3 V (vs Na⁺/Na), the honeycomb-layered compound Na(Ni 2/3Sb 1/3)O₂ can deliver up to 130 mAh/g of capacity at voltages above 3 V with this capacity concentrated in plateaus at 3.27 and 3.64 V. Comprehensive crystallographic studies have been carried out in order to understand the role of disorder in this system which can be prepared in both “disordered” and “ordered” forms,more » depending on the synthesis conditions. The average structure of Na(Ni 2/3Sb 1/3)O₂ is always found to adopt an O3-type stacking sequence, though different structures for the disordered (R3¯ m, #166, a = b = 3.06253(3) Å and c = 16.05192(7) Å) and ordered variants ( C2/m, #12, a = 5.30458(1) Å, b = 9.18432(1) Å, c = 5.62742(1) Å and β = 108.2797(2)°) are demonstrated through the combined Rietveld refinement of synchrotron X-ray and time-of-flight neutron powder diffraction data. However, pair distribution function studies find that the local structure of disordered Na(Ni 2/3Sb 1/3)O₂ is more correctly described using the honeycomb-ordered structural model, and solid state NMR studies confirm that the well-developed honeycomb ordering of Ni and Sb cations within the transition metal layers is indistinguishable from that of the ordered phase. The disorder is instead found to mainly occur perpendicular to the honeycomb layers with an observed coherence length of not much more than 1 nm seen in electron diffraction studies. When the Na environment is probed through ²³Na solid state NMR, no evidence is found for prismatic Na environments, and a bulk diffraction analysis finds no evidence of conventional stacking faults. The lack of long range coherence is instead attributed to disorder among

  4. Predictions of ground states of LiGa and NaGa

    NASA Astrophysics Data System (ADS)

    Boldyrev, Alexander I.; Simons, Jack

    1996-11-01

    The ground and very low-lying excited states of LiGa and NaGa have been studied using high level ab initio techniques. At the QCISD(T)/6-311 + G(2df) level of theory, the 1Σ + state was found to be the most stable for both molecules. The equilibrium bond lengths and dissociation energies were found to be: R( LiGa) = 2.865 Å and D0(LiGa) = 22.3 kcal/mol and R( NaGa) = 3.174 Å and D0(NaGa) = 17.1 kcal/mol. Trends within the ground electronic states of LiB, NaB, LiAl, NaAl, LiGa and NaGa are discussed and predictions for related AlkM (Alk LiCs and MBTl) species are made.

  5. The Role of Na,k-Atpase α Subunit Serine 775 and Glutamate 779 in Determining the Extracellular K+And Membrane Potential–Dependent Properties of the Na,k -Pump

    PubMed Central

    Peluffo, R. Daniel; Argüello, José M.; Berlin, Joshua R.

    2000-01-01

    The roles of Ser775 and Glu779, two amino acids in the putative fifth transmembrane segment of the Na,K -ATPase α subunit, in determining the voltage and extracellular K + (K + o) dependence of enzyme-mediated ion transport, were examined in this study. HeLa cells expressing the α1 subunit of sheep Na,K -ATPase were voltage clamped via patch electrodes containing solutions with 115 mM Na+ (37°C). Na,K -pump current produced by the ouabain-resistant control enzyme (RD), containing amino acid substitutions Gln111Arg and Asn122Asp, displayed a membrane potential and K + o dependence similar to wild-type Na,K -ATPase during superfusion with 0 and 148 mM Na+-containing salt solutions. Additional substitution of alanine at Ser775 or Glu779 produced 155- and 15-fold increases, respectively, in the K + o concentration that half-maximally activated Na,K -pump current at 0 mV in extracellular Na+-free solutions. However, the voltage dependence of Na,K -pump current was unchanged in RD and alanine-substituted enzymes. Thus, large changes in apparent K + o affinity could be produced by mutations in the fifth transmembrane segment of the Na,K -ATPase with little effect on voltage-dependent properties of K + transport. One interpretation of these results is that protein structures responsible for the kinetics of K + o binding and/or occlusion may be distinct, at least in part, from those that are responsible for the voltage dependence of K + o binding to the Na,K -ATPase. PMID:10871639

  6. Thermodynamic modeling of hydrogen storage capacity in Mg-Na alloys.

    PubMed

    Abdessameud, S; Mezbahul-Islam, M; Medraj, M

    2014-01-01

    Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.

  7. 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.

  8. Fluoride gastrointestinal absorption from Na2FPO3/CaCO3- and NaF/SiO2-based toothpastes.

    PubMed

    Falcão, A; Tenuta, L M A; Cury, J A

    2013-01-01

    Depending on toothpaste formulation, part of the fluoride is insoluble and would not be totally absorbable in the gastrointestinal tract, thus changing dental fluorosis risk estimation. This hypothesis was tested with formulations with either all fluoride in a soluble form (NaF/SiO2-based toothpaste, 1,100 µg F/g as labeled, 1,129.7 ± 49.4 µg F/g soluble fluoride as analyzed) or with around 20% of insoluble fluoride (Na2FPO3/CaCO3-based toothpaste, 1,450 µg F/g as labeled, 1,122.4 ± 76.4 µg F/g soluble fluoride as analyzed). Toothpastes were evaluated either fresh or after accelerated aging, which increased insoluble fluoride to 40% in the Na2FPO3/CaCO3-based toothpaste. In a blind, crossover clinical trial conducted in five legs, 20 adult volunteers ingested 49.5 µg of total fluoride/kg body weight from each formulation or purified water (control). Whole saliva and urine were collected as bioavailability indicators, and pharmacokinetics parameters calculated showed significantly (p < 0.05) lower fluoride bioavailability for Na2FPO3/CaCO3 toothpaste, which was reduced further after aging. A significant correlation between the amount of soluble fluoride ingested, but not total fluoride, and fluoride bioavailability was found (r = 0.57, p < 0.0001). The findings suggest that the estimated fluorosis risk as a result of ingestion of Na2FPO3/CaCO3-based toothpastes should be calculated based on the toothpaste's soluble rather than total fluoride concentration. Copyright © 2012 S. Karger AG, Basel.

  9. Study on cross-reactivity to the para group.

    PubMed

    Picardo, M; Cannistraci, C; Cristaudo, A; De Luca, C; Santucci, B

    1990-01-01

    In 80 patients, positive to at least one hapten of the para group (para-phenylenediamine, diaminodiphenylmethane, benzocaine, PPD mix), patch tests were carried out with freshly prepared solutions of para-phenylenediamine (PPD) and of 3 selected aromatic compounds related structurally to PPD (para-aminophenol, ortho-aminophenol, hydroquinone). The number of positive reactions correlated with the rate of decomposition of the substances as evaluated by high-pressure liquid chromatography. PPD, which was almost decomposed after 24 h, gave the highest number of positive reactions, followed by ortho-aminophenol and by para-aminophenol, while hydroquinone, which was oxidized to the extent of 35%, did not give any reactions. To evaluate if a different rate of oxidation can modify the patch test response, in the same patients and in 10 normal volunteers, tests were carried out with PPD solutions containing the oxidizing agent silver oxide (0.1%). By this procedure a significant increase in the number of positive responses was observed. The results suggest that the rate of decomposition and therefore the amount of quinone(s) generated, might be the key to eliciting patch test responses to oxidizable aromatic haptens.

  10. Transport properties and electronic structure of Na0.28PtSi

    NASA Astrophysics Data System (ADS)

    Itahara, Hiroshi; Suzumura, Akitoshi; Oh, Song-Yul

    2017-07-01

    We have investigated the electronic structure and properties of Na0.28PtSi, which is a Pt-based intermetallic compound with no reported physical properties. Na0.28PtSi powder with an average grain size of 15 µm was demonstrated to be stable in a strongly acidic aqueous solution. The ab initio calculations revealed that there is a band crossing the Fermi level and that the density of states (DOS) under the Fermi level mainly consists of d orbitals of Pt atoms. Here, we used the model of Na0.25PtSi with an approximately ordered structure (space group I4, full Na site occupation), which was set instead of the reported statistically disordered structure of Na0.28PtSi (I4/mcm, Na site occupancy: 0.258). The calculated electronic structure corresponded to the measured metallic properties of the Na0.28PtSi sintered body: i.e., the electrical resistivity of Na0.28PtSi was increased from 1.77 × 10-8 Ω m at 30 K to 2.67 × 10-7 Ω m at 300 K and the Seebeck coefficient was 0.11 µV K-1 at 300 K.

  11. Raman spectra from very concentrated aqueous NaOH and from wet and dry, solid, and anhydrous molten, LiOH, NaOH, and KOH.

    PubMed

    Walrafen, George E; Douglas, Rudolph T W

    2006-03-21

    High-temperature, high-pressure Raman spectra were obtained from aqueous NaOH solutions up to 2NaOHH2O, with X(NaOH)=0.667 at 480 K. The spectra corresponding to the highest compositions, X(NaOH)> or =0.5, are dominated by H3O2-. An IR xi-function dispersion curve for aqueous NaOH, at 473 K and 1 kbar, calculated from the data of Franck and Charuel indicates that the OH- ion forms H3O2- by preferential H bonding with nonhydrogen-bonded OH groups. Raman spectra from wet to anhydrous, solid LiOH, NaOH, and KOH yield sharp, symmetric OH- stretching peaks at 3664, 3633, and 3596 cm(-1), respectively, plus water-related, i.e., H3O2-, peaks near LiOH, 3562 cm(-1), NaOH, 3596 cm(-1), and, KOH, 3500 cm(-1). Absence of H3O2- peaks from the solid assures that the corresponding melt is anhydrous. Raman spectra from the anhydrous melts yield OH- stretching peak frequencies: LiOH, 3614+/-4 cm(-1), 873 K; NaOH, 3610+/-2 cm(-1), 975 K; and, KOH, 3607+/-2 cm(-1), 773 K, but low-frequency asymmetry due to ion-pair interactions is present which is centered near 3550 cm(-1). The ion-pair-related asymmetry corresponds to the sole IR maximum near 3550 cm(-1) from anhydrous molten NaOH, at 623 K. Bose-Einstein correction of published low-frequency Raman data from molten LiOH revealed an acoustic phonon, near 205 cm(-1), related to restricted translation of OH- versus Li+, and an optical phonon, at 625 cm(-1) and tau approximately 0.05 ps, due to protonic precession and/or pendular motion. Strong H bonding between water and the O atom of OH- forms H3O2-, but the proton of OH- does not bond with H significantly. Large Raman bandwidths (aqueous solutions) are explained in terms of inhomogeneous broadening due to proton transfer in a double well. Vibrational assignments are presented for H3O2-.

  12. Na-KATPase activity and intracellular ion concentrations in the lactating guinea pig mammary gland. Studies on Na-K activated adenosine triphosphatase, XXXVI.

    PubMed

    Vreeswijk, J H; de Pont, J J; Bonting, S L

    1975-01-01

    The intracellular sodium, potassium and chloride concentrations in slices of lactating guinea pig mammary gland have been determined by chemical analysis and the use of appropriate values for extracellular space. These ion concentrations after 1 hr incubation at 37 degrees C in a Krebs-Ringer bicarbonate solution are 45mM Na+, 138 mM K+ and 44 mM Cl-, which values are in agreement with those found in fresh mammary gland slices. Inhibition of the NaK activated ATPase cation pump system of the tissue by 10(-4)M ouabain, anoxia or cooling to 0 degrees C Causes a gain of Na+ and an equimolar loss of K+ without a significant change in chloride concentration. The effect of cooling (0 degrees C) is reversible by reincubation at 37 degrees C. Water content of the tissue (76.5% of wet weight) and extracellular space (40.5%) do not change under these conditions. The results permit the conclusion that the NaK activated ATPase system is responsible for the maintenance of the intracellular Na+ and K+ concentrations, but do not support the presence of a chloride pump.

  13. CCCP activation of the reconstituted NaK-pump.

    PubMed

    Yoda, A; Yoda, S

    1990-08-01

    In the NaK-ATPase proteoliposomes (PLs), the NaK-pump activity, Na+ uptake, and ATP hydrolysis were apparently enhanced by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and other ionophores without ion gradients. These ionophore effects were not cation specific. Without ionophores, the PL's ATPase activity fell to its steady-state value within 3 sec at 15 degrees C. This decrease in activity disappeared in the presence of CCCP. Since CCCP is believed to enhance proton mobility across the lipid bilayer and dissipate membrane potential (Vm), we postulated that a Vm build-up partially inhibits the PLs by changing the conformation of the NaK-pump, and that CCCP eliminated this partial inhibition. Since this activation required extracellular K+ and high ATP concentration in the PLs, CCCP must affect the conversion between the phosphorylated forms of NaK-ATPase (EP); this step has been suggested by Goldschlegger et al. (1987) to be the voltage-sensitive step (J. Physiol. (London) 387:331-355). Although cytoplasmic K+ accelerated the change of ADP- and K(+)-sensitive EP (E*P) to K(+)-sensitive ADP-insensitive EP (E2P), CCCP did not complete with cytoplasmic K+ when cytoplasmic Na+ was saturated. When the PLs were phosphorylated with 20 microM ATP and 20 microM palmitoyl CoA instead of with high concentration of ATP, CCCP increased the E*P content and decreased the ADP-sensitive K(+)-insensitive EP (E1P). The results described above suggest that CCCP affects the E1P to E*P change in the E1P----E*P----E2P conversion and that this reaction step is inhibited by Vm.

  14. Programa de conservacion para aves migratorias neotropicales

    Treesearch

    Deborah Finch; Marcia Wilson; Roberto Roca

    1992-01-01

    Mas de 250 especies de aves terrestres migran a Norte America durante la epoca reproductiva para aprovechar los sistemas templados. No obstante, las aves migratorias neotropicales pasan la mayor parte de su ciclo de vida en los habitat tropicales y subtropicales de paises latinoamericanos y caribefios donde viven en una asociacion cercana con las aves residentes. Para...

  15. Synthesis of carbon-coated Na2MnPO4F hollow spheres as a potential cathode material for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Wu, Ling; Hu, Yong; Zhang, Xiaoping; Liu, Jiequn; Zhu, Xing; Zhong, Shengkui

    2018-01-01

    Hollow sphere structure Na2MnPO4F/C composite is synthesized through spray drying, following in-situ pyrolytic carbon coating process. XRD results indicate that the well crystallized composite can be successfully synthesized, and no other impurity phases are detected. SEM and TEM results reveal that the Na2MnPO4F/C samples show intact hollow spherical architecture, and the hollow spherical shells with an average thickness of 150 nm-250 nm are composed of nanosized primary particles. Furthermore, the amorphous carbon layer is uniformly coated on the surface of the hollow sphere, and the nanosized Na2MnPO4F particles are well embedded in the carbon networks. Consequently, the hollow sphere structure Na2MnPO4F/C shows enhanced electrochemical performance. Especially, it is the first time that the obvious potential platforms (∼3.6 V) are observed during the charge and discharge process at room temperature.

  16. Synthesis of Pure Ca(OH)2 Nanoparticles and Superhydrophobic Suspensions: Consolidation and Waterproofing of Architectural Heritage Materials

    NASA Astrophysics Data System (ADS)

    Madrid Mendoza, Juan Antonio

    El objetivo de esta tesis es investigar sobre la sintesis, propiedades y aplicaciones de las nanoparticulas de Ca(OH)2 para consolidar materiales patrimoniales arquitectonicos. Las nanoparticulas de Ca(OH)2 se han utilizado recientemente en la conservacion del patrimonio, aunque algunos aspectos de la sintesis no son completamente comprendidos. En el presente estudio, hemos desarrollado metodos optimizados para obtener nanoparticulas de alta pureza mediante sintesis de fase homogenea y heterogenea utilizando diferentes materiales de partida. Se han realizado del orden de cien sintesis en diferentes condiciones para comprobar la validez y fiabilidad del metodo sintetico. Los resultados confirman que la temperatura de reaccion tiene una gran influencia en el tamano y la morfologia de las nanoparticulas de Ca(OH)2. Ademas, se ha investigado la estabilidad de las nanoparticulas a lo largo del tiempo en mezclas de 2-propanol / agua, en las que se encontro que la ausencia de agua era critica para evitar la aglomeracion de Ca(OH)2. Una vez dispersas en 2-propanol, las nanoparticulas se han utilizado para consolidar sustratos reales (piedra, adobe y estuco) confirmando su alto rendimiento en terminos de consolidacion superficial y - cuando se mezcla con ciertos surfactantes - en reduccion de la absorcion de agua. Asimismo, se ha investigado el uso de nanoparticulas modificadas basadas en M(OH)2, donde M=Ca2+, Mg2+, con el objetivo de mejorar tanto la cohesion superficial como la durabilidad de los materiales patrimoniales (p. ej. piedra Tabaire). Finalmente, el tratamiento de consolidacion basado en nanoparticulas puras de Ca(OH)2 se utilizo en emplazamientos con valor patrimonial, como edificios historicos y yacimientos arqueologicos (Teatro Romano de Cartagena) obteniendo resultados satisfactorios. The aim of this thesis is to investigate on the synthesis, properties and applications of Ca(OH)2 nanoparticles to consolidate architectural heritage materials. Ca(OH)2

  17. Polymorphism and Modulation of Para-Substituted l-Phenylalanine.

    PubMed

    Sögütoglu, Leyla-Cann; Lutz, Martin; Meekes, Hugo; de Gelder, René; Vlieg, Elias

    2017-12-06

    The crystal structure of para -methyl-l-phenylalanine at 230 K resembles that of the para-fluorinated analogue from the literature but is commensurately modulated with seven molecules in the asymmetric unit ( Z ' = 7). At 100 K, the superstructure loses its modulation, leading to a unit cell with Z ' = 1, with clear disorder in the phenyl ring orientations. The methyl-substituent in para -methyl-l-phenylalanine has, in contrast to fluorine, no polar interactions with protons of neighboring molecules, which might allow for the well-defined modulation of the crystal structure at 230 K.

  18. Downstream of downtown: urban wastewater as groundwater recharge

    NASA Astrophysics Data System (ADS)

    Foster, S. S. D.; Chilton, P. J.

    , especialmente en los climas más áridos. A pesar de ello, dicho componente todavía es una consecuencia secundaria (o incluso accidental) de diversas prácticas asociadas con la manipulación de las aguas residuales y con la reutilitzación de aguas depuradas. Este tema se revisa mediante referencias a ciertas áreas en las que existen investigación detallada de campo, identificando enfoques pragmáticos con el fin de reducir el riesgo de contaminación de las aguas subterráneas por tales prácticas, a la vez tratando de conservar los beneficios para los recursos del acuífero. Dado que los efluentes de aguas residuales urbanas son probablemente la única `fuente natural' cuya disponibilidad global se halla en del aumento, la importancia socioeconómica de este tema será evidente para los centros urbanos de rápido desarrollo en Asia, Latinoamérica y Oriente Medio.

  19. 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

  20. Sediment Budget Calculations Oceanside, California.

    DTIC Science & Technology

    1983-12-01

    Volume of Sediment Dredged from Agua Hedionda Lagoon vs. Time ............................. 13 7 Cumulative Volume of Accretion or Erosion as a Function...17 10 Oceanside Sub-Cell 2-3, Oceanside Harbor ............ 17 11 Oceanside Sub-Cell 3-4, Oceanside Harbor to Agua Hedionda Lagoon...18 12 Oceanside Sub-Cell 4-5, Agua Hedionda Lagoon ........ 18 13 Oceanside Sub-Cell 5-6, Agua Hedionda Lagoon to Southern

  1. Urea inhibits NaK2Cl cotransport in human erythrocytes.

    PubMed Central

    Lim, J; Gasson, C; Kaji, D M

    1995-01-01

    We examined the effect of urea on NaK2Cl cotransport in human erythrocytes. In erythrocytes from nine normal subjects, the addition of 45 mM urea, a concentration commonly encountered in uremic subjects, inhibited NaK2Cl cotransport by 33 +/- 7%. Urea inhibited NaK2Cl cotransport reversibly, and in a concentration-dependent fashion with half-maximal inhibition at 63 +/- 10 mM. Acute cell shrinkage increased, and acute cell swelling decreased NaK2Cl cotransport in human erythrocytes. Okadaic acid (OA), a specific inhibitor of protein phosphatase 1 and 2A, increased NaK2Cl cotransport by nearly 80%, suggesting an important role for these phosphatases in the regulation of NaK2Cl cotransport. Urea inhibited bumetanide-sensitive K influx even when protein phosphatases were inhibited with OA, suggesting that urea acted by inhibiting a kinase. In cells subjected to shrinking and OA pretreatment, maneuvers expected to increase the net phosphorylation, urea inhibited cotransport only minimally, suggesting that urea acted by causing a net dephosphorylation of the cotransport protein, or some key regulatory protein. The finding that concentrations of urea found in uremic subjects inhibited NaK2Cl cotransport, a widespread transport pathway with important physiological functions, suggests that urea is not only a marker for accumulation of other uremic toxins, but may be a significant uremic toxin itself. PMID:7593597

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

    NASA Technical Reports Server (NTRS)

    Nash, Douglas B.

    1988-01-01

    A previously reported laboratory determination of the IR spectrum of Na2S is presently noted to have been incorrectly interpreted, due to the inadvertent contamination of the sample with Na2CO3. New Na2S spectra are presented, and the Na2CO3 spectrum is examined in order to demonstrate that this phase is the primary sample contaminant. Na2S is a candidate surface component on the Jupiter satellite, Io, in view of its apparent high IR brightness and spectral neutrality in the 1-5 micron range.

  3. U. S. EPA’S NA APPROACH FOR PETROLEUM HYDROCARBONS

    EPA Science Inventory

    Most evaluations of NA of petroleum hydrocarbons use geochemical data to document the NA through biodegradation. The expected trends during biodegradation (plume interior vs. background concentrations) are Dissolved oxygen concentrations below background, Nitrate concentrations ...

  4. Para hydrogen equilibration in the atmospheres of the outer planets

    NASA Technical Reports Server (NTRS)

    Conrath, Barney J.

    1986-01-01

    The thermodynamic behavior of the atmospheres of the Jovian planets is strongly dependent on the extent to which local thermal equilibration of the ortho and para states of molecular hydrogen is achieved. Voyager IRIS data from Jupiter imply substantial departures of the para hydrogen fraction from equilibrium in the upper troposphere at low latitudes, but with values approaching equilibrium at higher latitudes. Data from Saturn are less sensitive to the orth-para ratio, but suggest para hydrogen fractions near the equilibrium value. Above approximately the 200 K temperature level, para hydrogen conversion can enhance the efficiency of convection, resulting in a substantial increase in overturning times on all of the outer planets. Currently available data cannot definitively establish the ortho-para ratios in the atmospheres of Uranus and Neptune, but suggest values closer to local equilibrium than to the 3.1 normal ratio. Modeling of sub-millimeter wavelength measurements of these planets suggest thermal structures with frozen equilibrium lapse rates in their convective regions.

  5. Interpretation of Na-K-Mg relations in geothermal waters

    USGS Publications Warehouse

    Fournier, R.O.

    1990-01-01

    When using a Na-K-???Mg triangular diagram as an aid in the interpretation of a geothermal water, the estimated temperature of last water-rock equilibration may change by as much as 50??C, depending on which of the many Na/K geothermometers one assumes is correct. A particular geothermometer may work well in one place and not in another because of differences in the mineralogy of the phases that are in contact with the reservoir fluid. The position of the full equilibrium line that is used for geothermometry and for assessing degrees of departure from equilibrium also changes as the assumed K/???Mg geothermometer equation changes. The degree of ambiguity can be evaluated by utilizing the results of all the recently published Na/K geothermometers on a single Na-K-???Mg triangular plot.

  6. The Ratio of Ortho- to Para-H2 in Photodissociation Regions

    NASA Technical Reports Server (NTRS)

    Sternberg, Amiel; Neufeld, David A.

    1999-01-01

    We discuss the ratio of ortho- to para-H2 in photodissociation regions (PDRs). We draw attention to an apparent confusion in the literature between the ortho-to-para ratio of molecules in FUV-pumped vibrationally excited states and the total H2 ortho-to-para abundance ratio. These ratios are not the same because the process of FUV pumping of fluorescent H2 emission in PDRs occurs via optically thick absorption lines. Thus gas with an equilibrium ratio of ortho- to para-H2 equal to 3 will yield FUV-pumped vibrationally excited ortho-to-para ratios smaller than 3, because the ortho-H2 pumping rates are preferentially reduced by optical depth effects. Indeed, if the ortho and para pumping lines are on the "square root" part of the curve of growth, then the expected ratio of ortho and para vibrational line strengths is 3(sup 1/2) approximately 1.7, close to the typically observed value. Thus, contrary to what has sometimes been stated in the literature, most previous measurements of the ratio of ortho- to para-H2 in vibrationally excited states are entirely consistent with a total ortho-to-para ratio of 3, the equilibrium value for temperatures greater than 200 K. We present an analysis and several detailed models that illustrate the relationship between the total ratios of ortho- to para-H2 and the vibrationally excited ortho-to-para ratios in PDRs. Recent Infrared Space Observatory measurements of pure rotational and vibrational H2 emissions from the PDR in the star-forming region S140 provide strong observational support for our conclusions.

  7. Sodium relations in desert plants: 8. Differential effects of NaCl and Na/sub 2/SO/sub 4/ on growth and composition of Atriplex hymenelytra (desert holly)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Soufi, S.M.; Wallace, A.

    1982-07-01

    Maximum growth over a period of 3 months of Atriplex hymenelytra (Torr.) Wats. (desert holly) in solution culture was obtained when the nutrient solution contained 5 x 10/sup -2/ N NaCl. Sodium concentratons in leaves at maximum yield was 7.88% and that of Cl was also 7.88%. In the presence of 10/sup -2/ N Na/sub 2/SO/sub 4/, there was much less growth than with 10/sup -2/ N NaCl. The highest NaCl level depressed levels of K, Ca, and Mg in leaves, stems, and roots. The highest NaCl level also decreased levels of micronutrients in many of the plants.

  8. Towards a double field theory on para-Hermitian manifolds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vaisman, Izu

    In a previous paper, we have shown that the geometry of double field theory has a natural interpretation on flat para-Kähler manifolds. In this paper, we show that the same geometric constructions can be made on any para-Hermitian manifold. The field is interpreted as a compatible (pseudo-)Riemannian metric. The tangent bundle of the manifold has a natural, metric-compatible bracket that extends the C-bracket of double field theory. In the para-Kähler case, this bracket is equal to the sum of the Courant brackets of the two Lagrangian foliations of the manifold. Then, we define a canonical connection and an action ofmore » the field that correspond to similar objects of double field theory. Another section is devoted to the Marsden-Weinstein reduction in double field theory on para-Hermitian manifolds. Finally, we give examples of fields on some well-known para-Hermitian manifolds.« less

  9. Ameloblast Modulation and Transport of Cl−, Na+, and K+ during Amelogenesis

    PubMed Central

    Bronckers, A.L.J.J.; Lyaruu, D.; Jalali, R.; Medina, J.F.; Zandieh-Doulabi, B.; DenBesten, P.K.

    2015-01-01

    Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na+K+-dependent calcium transporter NCKX4 and the Na+-dependent HPO42– (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr, Ae2a,b, and Amelx, according to quantitative x-ray electron probe microanalysis. Immunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-2b and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl− was strongly reduced; 2) K+ and Na+ accumulated (Na+ not in Amelx-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na+K+-dependent calcium transporter (likely NCKX4) and a Na+-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca2+, Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport

  10. Thermoelectric Performance of Na-Doped GeSe

    PubMed Central

    2017-01-01

    Recently, hole-doped GeSe materials have been predicted to exhibit extraordinary thermoelectric performance owing largely to extremely low thermal conductivity. However, experimental research on the thermoelectric properties of GeSe has received less attention. Here, we have synthesized polycrystalline Na-doped GeSe compounds, characterized their crystal structure, and measured their thermoelectric properties. The Seebeck coefficient decreases with increasing Na content up to x = 0.01 due to an increase in the hole carrier concentration and remains roughly constant at higher concentrations of Na, consistent with the electrical resistivity variation. However, the electrical resistivity is large for all samples, leading to low power factors. Powder X-ray diffraction and scanning electron microscopy/energy-dispersive spectrometry results show the presence of a ternary impurity phase within the GeSe matrix for all doped samples, which suggests that the optimal carrier concentration cannot be reached by doping with Na. Nevertheless, the lattice thermal conductivity and carrier mobility of GeSe is similar to those of polycrystalline samples of the leading thermoelectric material SnSe, leading to quality factors of comparable magnitude. This implies that GeSe shows promise as a thermoelectric material if a more suitable dopant can be found. PMID:29302637

  11. Spatial and mineralogic variation of Na-Ca alteration in Laramide porphyry systems of Arizona

    NASA Astrophysics Data System (ADS)

    Runyon, S.; Seedorff, E.; Barton, M. D.; Mazdab, F. K.; Lecumberri-Sanchez, P.; Steele-MacInnis, M.

    2017-12-01

    Na-Ca alteration is characterized by the metasomatic addition of Ca ± Na and the loss of K. Minor volumes of Na-Ca alteration in Laramide porphyry systems develops from 3 to 8 km paleodepth. Mineral assemblages, mineral compositions, hydrogen isotopes, whole-rock analyses, and reconnaissance fluid inclusion characteristics have been documented for Na-Ca alteration in Laramide porphyry systems such as Tea Cup and Sierrita. Volumetrically minor Na-Ca alteration in Laramide porphyry systems documented in this study commonly takes the form of one of three mineral assemblages: albite-epidote-chlorite, Na-plagioclase-actinolite ± epidote, and garnet- or diopside-stable Na-plagioclase-actinolite ± epidote. These different Na-Ca mineral assemblages have broad spatial relationships, from shallow albite-chlorite-epidote to deeper Na-plagioclase-actinolite within a given district. Hydrogen isotope data on Na-Ca alteration minerals shows consistently distinct δD compositions of Na-Ca alteration minerals compared to igneous minerals in a given district. Further, calculated hydrogen isotope composition of fluids in equilibrium with Na-Ca alteration minerals are consistently enriched in δD compared to magmatic-hydrothermal fluids. Whole-rock analyses show consistent losses of K and variable addition of Na and Ca across different Na-Ca alteration assemblages. Na-Ca alteration has been well documented associated with the Jurassic arc. Previous studies demonstrated through mass balance, timing and spatial relationships, isotopic, and fluid inclusion studies that Na-Ca alteration associated with the Jurassic arc likely formed from the circulation of external, highly saline, non-magmatic fluids (e.g., Battles and Barton, 1995; Dilles et al., 1995). Na-Ca alteration documented in Laramide systems is generally similar to Na-Ca alteration documented along the Jurassic arc in mineral assemblages, compositions, and timing, but the volume of Na-Ca alteration in the Laramide systems is

  12. Crebanine inhibits voltage-dependent Na+ current in guinea-pig ventricular myocytes.

    PubMed

    Xiao-Shan, He; Qing, Lin; Yun-Shu, Ma; Ze-Pu, Yu

    2014-01-01

    To study the effects of crebanine on voltage-gated Na(+) channels in cardiac tissues. Single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart. Voltage-dependent Na(+) current was recorded using the whole cell voltage-clamp technique. Crebanine reversibly inhibited Na(+) current with an IC50 value of 0.283 mmol·L(-1) (95% confidence range: 0.248-0.318 mmol·L(-1)). Crebanine at 0.262 mmol·L(-1) caused a negative shift (about 12 mV) in the voltage-dependence of steady-state inactivation of Na(+) current, and retarded its recovery from inactivation, but did not affect its activation curve. In addition to blocking other voltage-gated ion channels, crebanine blocked Na(+) channels in guinea-pig ventricular myocytes. Crebanine acted as an inactivation stabilizer of Na(+) channels in cardiac tissues. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  13. Physiological sodium concentrations enhance the iodide affinity of the Na+/I- symporter

    NASA Astrophysics Data System (ADS)

    Nicola, Juan P.; Carrasco, Nancy; Mario Amzel, L.

    2014-06-01

    The Na+/I- symporter (NIS) mediates active I- transport—the first step in thyroid hormonogenesis—with a 2Na+:1I- stoichiometry. NIS-mediated 131I- treatment of thyroid cancer post-thyroidectomy is the most effective targeted internal radiation cancer treatment available. Here to uncover mechanistic information on NIS, we use statistical thermodynamics to obtain Kds and estimate the relative populations of the different NIS species during Na+/anion binding and transport. We show that, although the affinity of NIS for I- is low (Kd=224 μM), it increases when Na+ is bound (Kd=22.4 μM). However, this Kd is still much higher than the submicromolar physiological I- concentration. To overcome this, NIS takes advantage of the extracellular Na+ concentration and the pronounced increase in its own affinity for I- and for the second Na+ elicited by binding of the first. Thus, at physiological Na+ concentrations, ~79% of NIS molecules are occupied by two Na+ ions and ready to bind and transport I-.

  14. Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

    PubMed Central

    Abdessameud, S.; Mezbahul-Islam, M.; Medraj, M.

    2014-01-01

    Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems. PMID:25383361

  15. Static and vibrational properties of equiatomic Na-based binary alloys

    NASA Astrophysics Data System (ADS)

    Vora, Aditya M.

    2007-09-01

    The computations of the static and vibrational properties of four equiatomic Na-based binary alloys viz. Na0.5Li0.5, Na0.5K0.5, Na0.5Rb0.5 and Na0.5Cs0.5, to second order in local model potential is discussed in terms of real-space sum of Born von Karman central force constants. The local field correlation functions due to Hartree (H), Ichimaru Utsumi (IU) and Sarkar et al. (S) are used to investigate the influence of the screening effects on the aforesaid properties. Results for the lattice constants C11, C12, C44, C12 C44, C12/C44 and bulk modulus B obtained using the H-local field correction function have higher values in comparison with the results obtained for the same properties using IU- and S-local field correction functions. The results for the Shear modulus (C‧), deviation from Cauchy's relation, Poisson's ratio σ, Young modulus Y, propagation velocity of elastic waves, phonon dispersion curves and degree of anisotropy A are highly appreciable for the four equiatomic Na-based binary alloys.

  16. Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media

    DOEpatents

    Arnold, F.H.; Moore, J.C.

    1999-05-25

    A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.

  17. Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media

    DOEpatents

    Arnold, Frances H.; Moore, Jeffrey C.

    1998-01-01

    A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.

  18. Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media

    DOEpatents

    Arnold, Frances H.; Moore, Jeffrey C.

    1999-01-01

    A method for isolating and identifying modified para-nitrobenzyl esterases which exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase.

  19. Para-nitrobenzyl esterases with enhanced activity in aqueous and nonaqueous media

    DOEpatents

    Arnold, F.H.; Moore, J.C.

    1998-04-21

    A method is disclosed for isolating and identifying modified para-nitrobenzyl esterases. These enzymes exhibit improved stability and/or esterase hydrolysis activity toward selected substrates and under selected reaction conditions relative to the unmodified para-nitrobenzyl esterase. The method involves preparing a library of modified para-nitrobenzyl esterase nucleic acid segments (genes) which have nucleotide sequences that differ from the nucleic acid segment which encodes for unmodified para-nitrobenzyl esterase. The library of modified para-nitrobenzyl nucleic acid segments is expressed to provide a plurality of modified enzymes. The clones expressing modified enzymes are then screened to identify which enzymes have improved esterase activity by measuring the ability of the enzymes to hydrolyze the selected substrate under the selected reaction conditions. Specific modified para-nitrobenzyl esterases are disclosed which have improved stability and/or ester hydrolysis activity in aqueous or aqueous-organic media relative to the stability and/or ester hydrolysis activity of unmodified naturally occurring para-nitrobenzyl esterase. 43 figs.

  20. Defect evolution and impurity migration in Na-implanted ZnO

    NASA Astrophysics Data System (ADS)

    Neuvonen, Pekka T.; Vines, Lasse; Venkatachalapathy, Vishnukanthan; Zubiaga, Asier; Tuomisto, Filip; Hallén, Anders; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

    2011-11-01

    Secondary ion mass spectrometry (SIMS) and positron annihilation spectroscopy (PAS) have been applied to study impurity migration and open volume defect evolution in Na+ implanted hydrothermally grown ZnO samples. In contrast to most other elements, the presence of Na tends to decrease the concentration of open volume defects upon annealing and for temperatures above 600∘C, Na exhibits trap-limited diffusion correlating with the concentration of Li. A dominating trap for the migrating Na atoms is most likely Li residing on Zn site, but a systematic analysis of the data suggests that zinc vacancies also play an important role in the trapping process.

  1. Organophosphate inhibition of avian salt gland Na, K-ATPase activity

    USGS Publications Warehouse

    Eastin, W.C.; Fleming, W.J.; Murray, H.C.

    1982-01-01

    1. Adult black ducks (Anas rubripes) were given freshwater or saltwater (1.5% NaCl) for 11 days and half of each group was also given an organophosphate (17 p.p.m. fenthion) in the diet on days 6–11.2. After 11 days, ducks drinking saltrwater had lost more weight and had higher plasma Na and uric acid concentration and osmolalities than birds drinking freshwater.3. Saltwater treatment stimulated the salt gland to increased weight and Na, K-ATPase activity.4. Fenthion generally reduced plasma and brain cholinesterase activity and depressed cholinesterase and Na, K-ATPase activities in salt glands of birds drinking saltwater.

  2. Para-hydrogen perspectives in hyperpolarized NMR.

    PubMed

    Glöggler, Stefan; Colell, Johannes; Appelt, Stephan

    2013-10-01

    The first instance of para-hydrogen induced polarization (PHIP) in an NMR experiment was serendipitously observed in the 1980s while investigating a hydrogenation reaction (Seldler et al., 1983; Bowers and Weitekamp, 1986, 1987; Eisenschmid et al., 1987) [1-4]. Remarkably a theoretical investigation of the applicability of para-hydrogen as a hyperpolarization agent was being performed in the 1980's thereby quickly providing a theoretical basis for the PHIP-effect (Bowers and Weitekamp, 1986) [2]. The discovery of signal amplification by a non-hydrogenating interaction with para-hydrogen has recently extended the interest to exploit the PHIP effect, as it enables investigation of compounds without structural alteration while retaining the advantages of spectroscopy with hyperpolarized compounds [5]. In this article we will place more emphasis of the future applications of the method while only briefly discussing the efforts that have been made in the understanding of the phenomenon and the development of the method so far. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. SLC4A11 is an EIPA-sensitive Na+ permeable pHi regulator

    PubMed Central

    Ogando, Diego G.; Jalimarada, Supriya S.; Zhang, Wenlin; Vithana, Eranga N.

    2013-01-01

    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 μM). The presence of 10 mM borate did not alter dpHi/dt or ΔpH 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

  4. The Na+-phosphate cotransport system (NaPi-II) with a cleaved protein backbone: implications on function and membrane insertion

    PubMed Central

    Kohl, Beate; Wagner, Carsten A; Huelseweh, Birgit; Busch, Andreas E; Werner, Andreas

    1998-01-01

    Renal handling of inorganic phosphate (Pi) involves a Na+-Pi cotransport system which is well conserved between vertebrates. The members of this protein family, denoted NaPi-II, share a topology with, it is thought, eight transmembrane domains. The transporter is proposed to be proteolytically cleaved within a large hydrophilic loop in vivo. The consequences of an interrupted backbone were tested by constructing cDNA clones encoding different N- (1-3 and 1-5) and C-terminal (4-8 and 6-8) complementary fragments of NaPi-II from winter flounder. When the cognate fragments were used in combination (1-3 plus 4-8; 1-5 plus 6-8) they comprised the full complement of the putative transporter domains. None of the four individual fragments or the 1-5 plus 6-8 combination when expressed in Xenopus oocytes increased Pi flux. Coexpression of fragments 1-3 plus 4-8 stimulated transport activity identical to that for expressed wild-type NaPi-II with regard to pH dependency and Km for Na+ and Pi binding; however, the maximal transport rate (vmax) was lower. Immunohistochemistry on cryosections confined the functionally active 1-3 plus 4-8 combination to the oocyte membrane. This was not the case for the 1-5 plus 6-8 combination or any of the individual fragments, all of which failed to induce fluorescence. A second immunohistochemical approach using intact oocytes allowed determination of the extracellular regions of the protein. Epitopes within the loop between transmembrane domains 3 and 4 enhanced fluorescence. Neither N- nor C-terminal tags induced fluorescence. PMID:9508800

  5. Effect of NaCl treatments on glucosinolate metabolism in broccoli sprouts*

    PubMed Central

    Guo, Rong-fang; Yuan, Gao-feng; Wang, Qiao-mei

    2013-01-01

    To understand the regulation mechanism of NaCl on glucosinolate metabolism in broccoli sprouts, the germination rate, fresh weight, contents of glucosinolates and sulforaphane, as well as myrosinase activity of broccoli sprouts germinated under 0, 20, 40, 60, 80, and 100 mmol/L of NaCl were investigated in our experiment. The results showed that glucoerucin, glucobrassicin, and 4-hydroxy glucobrassicin in 7-d-old broccoli sprouts were significantly enhanced and the activity of myrosinase was inhibited by 100 mmol/L of NaCl. However, the total glucosinolate content in 7-d-old broccoli sprouts was markedly decreased although the fresh weight was significantly increased after treatment with NaCl at relatively low concentrations (20, 40, and 60 mmol/L). NaCl treatment at the concentration of 60 mmol/L for 5 d maintained higher biomass and comparatively higher content of glucosinolates in sprouts of broccoli with decreased myrosinase activity. A relatively high level of NaCl treatment (100 mmol/L) significantly increased the content of sulforaphane in 7-d-old broccoli sprouts compared with the control. These results indicate that broccoli sprouts grown under a suitable concentration of NaCl could be desirable for human nutrition. PMID:23365011

  6. 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.

  7. Use-dependent inhibition of Na+ currents by benzocaine homologs.

    PubMed Central

    Quan, C; Mok, W M; Wang, G K

    1996-01-01

    Most local anesthetics (LAs) elicit use-dependent inhibition of Na+ currents when excitable membranes are stimulated repetitively. One exception to this rule is benzocaine, a neutral LA that fails to produce appreciable use-dependent inhibition. In this study, we have examined the use-dependent phenomenon of three benzocaine homologs: ethyl 4-diethylaminobenzoate, ethyl 4-ethoxybenzoate, and ethyl 4-hydroxybenzoate. Ethyl 4-hydroxybenzoate at 1 mM, like benzocaine, elicited little use-dependent inhibition of Na+ currents, whereas ethyl 4-diethylaminobenzoate at 0.15 mM and ethyl 4-ethoxybenzoate at 0.5 mM elicited substantial use-dependent inhibition--up to 55% of peak Na+ currents were inhibited by repetitive depolarizations at 5 Hz. Each of these compounds produced significant tonic block of Na+ currents at rest and shifted the steady-state inactivation curve (h infinity) toward the hyperpolarizing direction. Kinetic analyses showed that the decaying phase of Na+ currents during a depolarizing pulse was significantly accelerated by all drugs, thus suggesting that these drugs also block the activated channel. The recovery time course for the use-dependent inhibition of Na+ currents was relatively slow, with time constants of 6.8 and 4.4 s for ethyl 4-diethylaminobenzoate and ethyl 4-ethoxybenzoate, respectively. We conclude that benzocaine and 4-hydroxybenzoate interact with the open and inactivated channels during repetitive pulses, but during the interpulse the complex dissociates too fast to accumulate sufficient use-dependent block of Na+ currents. In contrast, ethyl 4-diethylaminobenzoate and ethyl 4-ethoxybenzoate dissociate slowly from their binding site and consequently elicit significant use-dependent block. A common LA binding site suffices to explain the presence and absence of use-dependent block by benzocaine homologs during repetitive pulses. PMID:8770198

  8. Suppression of NaNO3 crystal nucleation by glycerol: micro-Raman observation on the efflorescence process of mixed glycerol/NaNO3/water droplets.

    PubMed

    Yu, Jun-Ying; Zhang, Yun; Zeng, Guang; Zheng, Chuan-Ming; Liu, Yong; Zhang, Yun-Hong

    2012-02-09

    Although the hygroscopicity of a NaNO(3)/water microdroplet and a polyalcohol/water microdroplet, two of the most important aerosols in atmosphere, has been widely studied, little is known about the relationship between the hygroscopic behavior of mixed NaNO(3)/polyalcohol/water droplets and their structures on the molecular level. In this study, the hygroscopicity of mixed glycerol/NaNO(3)/water droplets deposited on a hydrophobic substrate was studied by micro-Raman spectroscopy with organic-to-inorganic molar ratios (OIRs) of 0.5, 1, and 2. In the mixed glycerol/NaNO(3)/water droplets, glycerol molecules tended to combine with Na(+) and NO(3)(-) ions by electrostatic interaction and hydrogen bonding, respectively. On the basis of the analyses of the changes of symmetric stretching (v(s)-CH(2)), asymmetric stretching (v(a)-CH(2)), their area ratio (Av(a)-CH(2)/Av(s)-CH(2)) of glycerol, and symmetric stretching band of NO(3)(-) (ν(1)-NO(3)(-)) with relative humidity (RH), it was found that the conformation of glycerol was transformed from αα mainly to γγ and partly to αγ with a decreasing RH in the mixed droplets, contrary to the case in the glycerol/water droplet. In addition, the glycerol with γγ and αγ conformation had strong interaction with Na(+) and NO(3)(-) respectively, which suppressed the formation of contact of ions and delayed the efflorescence relative humidity (ERH) for the mixed droplets compared to the NaNO(3)/water droplet. © 2012 American Chemical Society

  9. Neutral Na in comets tails: a chemical story

    NASA Astrophysics Data System (ADS)

    Ellinger, Y.; Pauzat, F.; Mousis, O.; Guilbert-Lepoutre, A.; Leblanc, F.; Ali-Dib, M.; Doronin, M.; Zicler, E.; Doressoundiram, A.

    2015-10-01

    The origin of the neutral sodium comet tail discovered in comet Hale-Bopp in 1997 is still a matter of discussion. Here we propose a scenario which is based on chemical grounds. The starting point is the chemical trapping of the Na+ ion in the refractory material during the condensation phase of the protosolar nebula, followed by its incorporation in the building blocks of the comets parent bodies. In the next step, the Na+ ions are washed out of the refractory material by the water formed by the melting of the ice due to the heat released in the radioactive decay of short period elements. When the water freezes again, the Na+ ion looses its positive charge to evolve progressively toward a neutral atom when approaching the surface of the ice. As shown by high-level numerical simulations based on first principle periodic density functional theory (DFT) to describe the solid structure of the ice, it is a neutral Na that is ejected with the sublimation of the ice top layer.

  10. BSSDATA - um programa otimizado para filtragem de dados em radioastronomia solar

    NASA Astrophysics Data System (ADS)

    Martinon, A. R. F.; Sawant, H. S.; Fernandes, F. C. R.; Stephany, S.; Preto, A. J.; Dobrowolski, K. M.

    2003-08-01

    A partir de 1998, entrou em operação regular no INPE, em São José dos Campos, o Brazilian Solar Spectroscope (BSS). O BSS é dedicado às observações de explosões solares decimétricas com alta resolução temporal e espectral, com a principal finalidade de investigar fenômenos associados com a liberação de energia dos "flares" solares. Entre os anos de 1999 e 2002, foram catalogadas, aproximadamente 340 explosões solares classificadas em 8 tipos distintos, de acordo com suas características morfológicas. Na análise detalhada de cada tipo, ou grupo, de explosões solares deve-se considerar a variação do fluxo do sol calmo ("background"), em função da freqüência e a variação temporal, além da complexidade das explosões e estruturas finas registradas superpostas ao fundo variável. Com o intuito de realizar tal análise foi desenvolvido o programa BSSData. Este programa, desenvolvido em linguagem C++, é constituído de várias ferramentas que auxiliam no tratamento e análise dos dados registrados pelo BSS. Neste trabalho iremos abordar as ferramentas referentes à filtragem do ruído de fundo. As rotinas do BSSData para filtragem de ruído foram testadas nos diversos grupos de explosões solares ("dots", "fibra", "lace", "patch", "spikes", "tipo III" e "zebra") alcançando um bom resultado na diminuição do ruído de fundo e obtendo, em conseqüência, dados onde o sinal torna-se mais homogêneo ressaltando as áreas onde existem explosões solares e tornando mais precisas as determinações dos parâmetros observacionais de cada explosão. Estes resultados serão apresentados e discutidos.

  11. Selective detection of hyperpolarized NMR signals derived from para-hydrogen using the Only Para-hydrogen SpectroscopY (OPSY) approach.

    PubMed

    Aguilar, Juan A; Adams, Ralph W; Duckett, Simon B; Green, Gary G R; Kandiah, Rathika

    2011-01-01

    A new family of NMR pulse sequences is reported for the recording of para-hydrogen enhanced NMR spectra. This Only Para-hydrogen SpectroscopY (OPSY) approach uses coherence selection to separate hyperpolarized signals from those of fully relaxed and thermally equilibrated protons. Sequence design, performance, practical aspects and applicability to other hyperpolarization techniques are discussed. Copyright © 2010 Elsevier Inc. All rights reserved.

  12. CAPE-2 Cubesat - ELaNa IV

    NASA Image and Video Library

    2016-07-25

    CAPE-2: Cajun Advanced Picosatellite Experiment – ELaNa IV CAPE-2 was developed by students from the University of Louisiana Lafayette to engage, inspire and educate K-12 students to encourage them to pursue STEM careers. The secondary focus is the technology demonstration of deployed solar panels to support the following payloads: text to speech, voice repeater, tweeting, email, file transfer and data collection from buoys. Launched by NASA’s CubeSat Launch Initiative on the ELaNa IV mission as an auxiliary payload aboard the U.S. Air Force-led Operationally Responsive Space (ORS-3) Mission on November 19, 2013.

  13. Deliquescence behavior of photo-irradiated single NaNO3 droplets

    NASA Astrophysics Data System (ADS)

    Seng, Samantha; Guo, Fangqin; Tobon, Yeny A.; Ishikawa, Tomoki; Moreau, Myriam; Ishizaka, Shoji; Sobanska, Sophie

    2018-06-01

    Nitrate-containing particles are ubiquitous in the troposphere because of their secondary production due to anthropogenic emissions of NOx from the combustion of fossil fuels. Nitrate ions are recognized as photoactive species that may contribute to the formation of oxidants in the atmosphere through heterogeneous photochemical reactions. The chemical transformation of aerosol particles in the atmosphere often leads to modification of the particles' hygroscopic properties. Although the photo-transformation of nitrate ions into nitrite within aerosol particles has been investigated, the influence of the photoproducts formation on the hygroscopic behavior of particles has not been reported. In this study, we examined the hygroscopic properties of single, ultraviolet-irradiated NaNO3 droplets using Raman microspectrometry. We are the first demonstrated that irradiating NaNO3 particles affects their hygroscopic behavior. For short-term exposures, regarding hygroscopic behavior, the irradiated particles exhibited two-stage transitions that were clearly reproduced in the experimental NaNO3-NaNO2 phase diagram. The production of NO2- decreased the deliquescence relative humidity values. For long irradiation times (>5 h), these values are even more affected by the additional production of peroxynitrite and carbonate ions in individual droplets. The NaNO3-NaNO2 deliquescence phase diagram cannot explain the hygroscopic behavior of long-term irradiated particles. Finally, we demonstrated the influence that CO2 has on the photo-transformation process in NaNO3 droplets.

  14. Basic diagnosis of solid waste generated at Agua Blanca State Park to propose waste management strategies.

    PubMed

    Laines Canepa, José Ramón; Zequeira Larios, Carolina; Valadez Treviño, Maria Elena Macías; Garduza Sánchez, Diana Ivett

    2012-03-01

    State parks are highly sensitive areas of great natural importance and tourism value. Herein a case study involving a basic survey of solid waste which was carried out in 2006 in Agua Blanca State Park, Macuspana, Tabasco, Mexico with two sampling periods representing the high and low tourist season is presented. The survey had five objectives: to find out the number of visitors in the different seasons, to consider the daily generation of solid waste from tourist activities, to determine bulk density, to select and quantify sub-products; and to suggest a possible treatment. A daily average of 368 people visited the park: 18,862 people in 14 days during the high season holiday (in just one day, Easter Sunday, up to 4425 visitors) and 2092 visitors in 43 days during the low season. The average weight of the generated solid waste was 61.267 kg day(-1) and the generated solid waste average per person was 0.155 kg person(-1 ) day(-1). During the high season, the average increased to 0.188 kg person(-1 ) day(-1) and during the low season, the average decreased to 0.144 kg person(-1 ) day(-1). The bulk density average was 75.014 kg m(-3), the maximum value was 92.472 kg m(-3) and the minimum was 68.274 kg m(-3). The sub-products comprised 54.52% inorganic matter; 32.03% organic matter, 10.60% non-recyclable and 2.85% others. Based on these results, waste management strategies such as reuse/recycling, aerobic and anaerobic digestion, the construction of a manual landfill and the employment of a specialist firm were suggested.

  15. Ensino de astronomia no 1o. e 2o. ciclos do nível fundamental e na educação de jovens e adultos: exemplos e discussões

    NASA Astrophysics Data System (ADS)

    Queiroz, A. S. B.; Jafelice, L. C.

    2003-08-01

    Tem-se constatado uma preocupante carência no ensino de astronomia nos diversos níveis de escolaridade. Neste trabalho discutimos várias práticas didático-pedagógicas que vimos desenvolvendo para crianças, jovens e adultos em processo de alfabetização, visando contribuir para reparar aquela carência. Propomos uma metodologia que incorpora as recentes exigências das políticas públicas educacionais, estimula o desenvolvimento de textos e materiais instrucionais, é compatível com a realidade desse público e é adaptável às respectivas faixas etárias. A observação do céu sempre esteve presente na vida de nossos antepassados, dando suporte à compreensão do ser humano como integrante da natureza. Visamos com este trabalho suprir a deficiência encontrada para se tratar a relação do ser humano com o céu, no ambiente escolar. Os resultados são animadores e envolvem práticas e textos que desenvolvemos e atividades realizadas pelos alunos. No primeiro grupo destacamos o desenvolvimento de várias práticas: "viagem aos planetas" (construímos o "foguete", os planetas em escala, contamos história e redigimos texto de orientação para os professores); "gnômon humano" (os próprios corpos dos alunos são usados para registrar o movimento aparente do Sol); "crateras da Lua" (concretização de "meteoritos" e "solo lunar" de gesso e exploração da relação entre energia cinética do bólido e tamanho da cratera formada); etc. No segundo grupo, produções de desenhos e redações e discussões dos alunos após a realização de cada prática, revelam que estas têm se mostrado muito eficientes, tanto para estimular a imaginação e a fantasia dos envolvidos, como para trabalhar-se habilidades, competências e conteúdos relacionados à astronomia, segundo uma perspectiva interdisciplinar contextualizada. (PPGECNM/UFRN; NUPA/USP; Temáticos/FAPESP)

  16. Mechanism of epithelial lithium transport. Evidence for basolateral Na:Na and Na:Li exchange

    PubMed Central

    1983-01-01

    Measurement of transmural sodium fluxes across isolated, ouabain- inhibited turtle colon in the presence of a serosal-to-mucosal sodium gradient shows that in the absence of active transport the amiloride- sensitive cellular path contains at least two routes for the transmural movement of sodium and lithium, one a conductive path and the other a nonconductive, cation-exchange mechanism. The latter transport element can exchange lithium for sodium, and the countertransport of these two cations provides a mechanistic basis for the ability of tight epithelia to actively absorb lithium despite the low affinity of the basolateral Na/K-ATPase for this cation. PMID:6644269

  17. Ultrafast multiphoton ionization dynamics and control of NaK molecules

    NASA Astrophysics Data System (ADS)

    Davidsson, Jan; Hansson, Tony; Mukhtar, Emad

    1998-12-01

    The multiphoton ionization dynamics of NaK molecules is investigated experimentally using one-color pump-probe femtosecond spectroscopy at 795 nm and intermediate laser field strengths (about 10 GW/cm2). Both NaK+ and Na+ ions are detected as a function of pulse separation time, pulse intensities, and strong pulse-weak pulse order. To aid in the analysis, the potential energy curves of the two lowest electronic states of NaK+ and the electronic transition dipole moment between them are calculated by the GAUSSIAN94 UCIS method. Different ionization pathways are identified by Franck-Condon analysis, and vibrational dynamics in the A 1Σ+ and 3 1Π states, as well as in the ground state, is observed. Further, the existence of a highly excited (above the adiabatic ionization limit) neutral state of NaK is proposed. By changing the strong pulse-weak pulse order of the pulses, the ionization pathways for production of both ions can be varied and thus controlled.

  18. Looking for the Phase Transition—Recent NA61/SHINE Results

    NASA Astrophysics Data System (ADS)

    Turko, Ludwik

    2018-03-01

    The fixed-target NA61/SHINE experiment (SPS CERN) looks for the critical point of strongly interacting matter and the properties of the onset of deconfinement. It is a two dimensional scan of measurements of particle spectra and fluctuations in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size, corresponding to a two dimensional phase diagram (temperature T - baryonic chemical potential $\\mu_B$). New NA61/SHINE results are presented here, such as transverse momentum and multiplicity fluctuations in Ar+Sc collisions compared to NA61/SHINE p+p and Be+Be data, as well as to earlier NA49 A+A results. Recently, a preliminary signature for the new size dependent effect - rapid changes in system size dependence was observed in NA61-SHINE data, labeled as percolation threshold or onset of fireball. This would be closely related to the vicinity of the hadronic phase transition region.

  19. Membrane permeable local anesthetics modulate NaV1.5 mechanosensitivity

    PubMed Central

    Beyder, Arthur; Strege, Peter R.; Bernard, Cheryl; Farrugia, Gianrico

    2012-01-01

    Voltage-gated sodium selective ion channel NaV1.5 is expressed in the heart and the gastrointestinal tract, which are mechanically active organs. NaV1.5 is mechanosensitive at stimuli that gate other mechanosensitive ion channels. Local anesthetic and antiarrhythmic drugs act upon NaV1.5 to modulate activity by multiple mechanisms. This study examined whether NaV1.5 mechanosensitivity is modulated by local anesthetics. NaV1.5 channels wereexpressed in HEK-293 cells, and mechanosensitivity was tested in cell-attached and excised inside-out configurations. Using a novel protocol with paired voltage ladders and short pressure pulses, negative patch pressure (-30 mmHg) in both configurations produced a hyperpolarizing shift in the half-point of the voltage-dependence of activation (V1/2a) and inactivation (V1/2i) by about -10 mV. Lidocaine (50 µM) inhibited the pressure-induced shift of V1/2a but not V1/2i. Lidocaine inhibited the tonic increase in pressure-induced peak current in a use-dependence protocol, but it did not otherwise affect use-dependent block. The local anesthetic benzocaine, which does not show use-dependent block, also effectively blocked a pressure-induced shift in V1/2a. Lidocaine inhibited mechanosensitivity in NaV1.5 at the local anesthetic binding site mutated (F1760A). However, a membrane impermeable lidocaine analog QX-314 did not affect mechanosensitivity of F1760A NaV1.5 when applied from either side of the membrane. These data suggest that the mechanism of lidocaine inhibition of the pressure-induced shift in the half-point of voltage-dependence of activation is separate from the mechanisms of use-dependent block. Modulation of NaV1.5 mechanosensitivity by the membrane permeable local anesthetics may require hydrophobic access and may involve membrane-protein interactions. PMID:22874086

  20. Na(7)Mg(13)Nd(PO(4))(12).

    PubMed

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

    2012-06-01

    Investigations of the quasi-ternary system Na(3)PO(4)-Mg(3)(PO(4))(2)-NdPO(4) allowed us to obtain the new phosphate hepta-sodium trideca-magnesium neodymium dodeca-kis-phosphate, Na(7)Mg(13)Nd(PO(4))(12), by applying a flux method. The crystal structure is isotypic with that of the previously reported Na(7)Mg(13)Ln(PO(4))(12) (Ln = Eu, La) compounds. It consists of a complex three-dimensional framework built up from an NdO(8) polyhedron (m symmetry), an MO(6) octa-hedron statistically occupied by M = Mg and Na, and eight MgO(x) (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 PO(4) tetra-hedra through common corners. Two of the PO(4) tetra-hedra 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 [Mg(4)MP(4)O(22)](∞) (2) layers extending parallel to (100) and stacked along [100], and [Mg(4)NdP(4)O(36)](∞) (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.

  1. Trehalose-producing enzymes MTSase and MTHase in Anabaena 7120 under NaCl stress.

    PubMed

    Asthana, Ravi K; Nigam, Subhasha; Maurya, Archana; Kayastha, Arvind M; Singh, Sureshwar P

    2008-05-01

    Salt tolerance, a multigenic trait, necessitates knowledge about biosynthesis and function of candidate gene(s) at the cellular level. Among the osmolytes, trehalose biosynthesis in cyanobacteria facing NaCl stress is little understood. Anabaena 7120 filaments exposed to 150 mM: NaCl fragmented and recovered on transfer to -NaCl medium with the increased heterocysts frequency (7%) over the control (4%). Cells failed to retain Na+ beyond a threshold [2.19 mM/cm3 (PCV)]. Whereas NaCl-stressed cells exhibited a marginal rise in K+ (1.1-fold) only at 30 h, for Na+ it was 130-fold at 48 h over cells in control. A time-course study (0-54 h) revealed reduction in intracellular Na+ beyond 48 h [0.80 mM/cm3 (PCV)] suggestive of ion efflux. The NaCl-stressed cells showed differential expression of maltooligosyltrehalose synthase (MTSase; EC 5.4.99.15) and maltooligosyltrehalose trehalohydrolase (MTHase; EC 3.2.1.141) depending on the time and the extent of intracellular Na+ buildup.

  2. Energetics of Na + Transport through the Electrode/Cathode Interface in Single Solvent Electrolytes

    DOE PAGES

    Browning, Katie L.; Sacci, Robert L.; Veith, Gabriel M.

    2017-01-27

    Here, the activation energy of desolvation for Na-ion electrolyte systems were studied using temperature dependent electrochemical impedance spectroscopy (EIS). Propylene carbonate (PC) and tetraglyme were chosen as solvents in single solvent electrolyte solution coupled with NaClO 4, NaPF 6, NaAsF 6, NaBF 4, and NaOFt salts. The results demonstrate the insertion and desolvation processes are extremely fast at or above room temperature. The data shows under optimal salt chemistry the desolvation activation energy is less than 21 kJ/mole. This is in contrast to the ~50 kJ/mole measured for analogous Li systems. The dominant factor affecting performance was the anion. Indeed,more » anions with lower donor numbers (PF 6 –, AsF 6 –) had more than 30 kJ/mole lower desolvation energies than species like NaBF 4 and NaOFt.« less

  3. Band gap engineering for graphene by using Na{sup +} ions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sung, S. J.; Lee, P. R.; Kim, J. G.

    2014-08-25

    Despite the noble electronic properties of graphene, its industrial application has been hindered mainly by the absence of a stable means of producing a band gap at the Dirac point (DP). We report a new route to open a band gap (E{sub g}) at DP in a controlled way by depositing positively charged Na{sup +} ions on single layer graphene formed on 6H-SiC(0001) surface. The doping of low energy Na{sup +} ions is found to deplete the π* band of graphene above the DP, and simultaneously shift the DP downward away from Fermi energy indicating the opening of E{sub g}.more » The band gap increases with increasing Na{sup +} coverage with a maximum E{sub g}≥0.70 eV. Our core-level data, C 1s, Na 2p, and Si 2p, consistently suggest that Na{sup +} ions do not intercalate through graphene, but produce a significant charge asymmetry among the carbon atoms of graphene to cause the opening of a band gap. We thus provide a reliable way of producing and tuning the band gap of graphene by using Na{sup +} ions, which may play a vital role in utilizing graphene in future nano-electronic devices.« less

  4. Energy landscape of the reactions governing the Na+ deeply occluded state of the Na+/K+-ATPase in the giant axon of the Humboldt squid

    PubMed Central

    Castillo, Juan P.; De Giorgis, Daniela; Basilio, Daniel; Gadsby, David C.; Rosenthal, Joshua J. C.; Latorre, Ramon; Holmgren, Miguel; Bezanilla, Francisco

    2011-01-01

    The Na+/K+ pump is a nearly ubiquitous membrane protein in animal cells that uses the free energy of ATP hydrolysis to alternatively export 3Na+ from the cell and import 2K+ per cycle. This exchange of ions produces a steady-state outwardly directed current, which is proportional in magnitude to the turnover rate. Under certain ionic conditions, a sudden voltage jump generates temporally distinct transient currents mediated by the Na+/K+ pump that represent the kinetics of extracellular Na+ binding/release and Na+ occlusion/deocclusion transitions. For many years, these events have escaped a proper thermodynamic treatment due to the relatively small electrical signal. Here, taking the advantages offered by the large diameter of the axons from the squid Dosidicus gigas, we have been able to separate the kinetic components of the transient currents in an extended temperature range and thus characterize the energetic landscape of the pump cycle and those transitions associated with the extracellular release of the first Na+ from the deeply occluded state. Occlusion/deocclusion transition involves large changes in enthalpy and entropy as the ion is exposed to the external milieu for release. Binding/unbinding is substantially less costly, yet larger than predicted for the energetic cost of an ion diffusing through a permeation pathway, which suggests that ion binding/unbinding must involve amino acid side-chain rearrangements at the site. PMID:22143771

  5. Energy landscape of the reactions governing the Na+ deeply occluded state of the Na+/K+-ATPase in the giant axon of the Humboldt squid.

    PubMed

    Castillo, Juan P; De Giorgis, Daniela; Basilio, Daniel; Gadsby, David C; Rosenthal, Joshua J C; Latorre, Ramon; Holmgren, Miguel; Bezanilla, Francisco

    2011-12-20

    The Na(+)/K(+) pump is a nearly ubiquitous membrane protein in animal cells that uses the free energy of ATP hydrolysis to alternatively export 3Na(+) from the cell and import 2K(+) per cycle. This exchange of ions produces a steady-state outwardly directed current, which is proportional in magnitude to the turnover rate. Under certain ionic conditions, a sudden voltage jump generates temporally distinct transient currents mediated by the Na(+)/K(+) pump that represent the kinetics of extracellular Na(+) binding/release and Na(+) occlusion/deocclusion transitions. For many years, these events have escaped a proper thermodynamic treatment due to the relatively small electrical signal. Here, taking the advantages offered by the large diameter of the axons from the squid Dosidicus gigas, we have been able to separate the kinetic components of the transient currents in an extended temperature range and thus characterize the energetic landscape of the pump cycle and those transitions associated with the extracellular release of the first Na(+) from the deeply occluded state. Occlusion/deocclusion transition involves large changes in enthalpy and entropy as the ion is exposed to the external milieu for release. Binding/unbinding is substantially less costly, yet larger than predicted for the energetic cost of an ion diffusing through a permeation pathway, which suggests that ion binding/unbinding must involve amino acid side-chain rearrangements at the site.

  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 α-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

  7. Rigidification of the autolysis loop enhances Na[superscript +] binding to thrombin

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pozzi, Nicola; Chen, Raymond; Chen, Zhiwei

    2011-09-20

    Binding of Na{sup +} 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{sup +} is weak due to large heat capacity and enthalpy changes associated with binding, and the K{sub d} = 80 mM ensures only 64% saturation of the site at the concentration of Na{sup +} in the blood (140 mM). Residues controlling Na{sup +} binding and activation have been identified. Yet, attempts to improve the interaction of Na{sup +} with thrombin and possibly increase catalyticmore » 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{sup +} 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{sup +} 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.« less

  8. Effect of NaCl concentration on productivity and mineral composition of Salicornia europaea as a potential crop for utilization NaCl in LSS

    NASA Astrophysics Data System (ADS)

    Ushakova, S. A.; Kovaleva, N. P.; Gribovskaya, I. V.; Dolgushev, V. A.; Tikhomirova, N. A.

    The accumulation of solid and liquid wastes in manmade ecosystems presents a problem that has not been efficiently solved yet. Urine, containing NaCl, are part of these products. This is an obstacle to the creation of biological systems with a largely closed material cycling, because the amount of solid and liquid wastes in them must be reduced to a minimum. A possible solution to the problem is to select plant species capable of utilizing sufficiently high concentrations of NaCl, edible for humans, and featuring high productivity. Until recently, the life support systems have included the higher plants that were either sensitive to salinization (wheat, many of the legumes, carrot, potato, maize) or relatively salt-resistant (barley, sugar beet, spinach). Salicomia europaea, whose above-ground part is fully edible for humans, is one of the most promising candidates to be included in life support systems. It is reported in the literature that this plant is capable of accumulating up to 50% NaCl (dry basis). Besides, excessive accumulation of sodium ions should bring forth a decrease in the uptake of potassium ions and other biogenic elements. The aim of this work is to study the feasibility of using S. europaea plants in growth chambers to involve NaCl into material cycling. Plants were grown in vegetation chambers at the irradiance of 100 or 150 W/m 2 PAR (photosynthetically active radiation) and the air temperature 24 °C, by two methods. The first method was to grow the plants on substrate - peat. The peat was supplemented with either 3% NaCl (Variant 1) or 6% NaCl (Variant 2) of the oven-dry mass of the peat. The second method was to grow the plants in water culture, using the solution with a full complement of nutrients, which contained 0.0005% of NaCl, 1% or 2%. The study showed that the addition of NaCl to the substrate or to the solution resulted in the formation of more succulent plants, which considerably increased their biomass. The amount of NaCl uptake

  9. The Salty Scrambled Egg: Detection of NaCl Toward CRL 2688

    NASA Astrophysics Data System (ADS)

    Highberger, J. L.; Thomson, K. J.; Young, P. A.; Arnett, D.; Ziurys, L. M.

    2003-08-01

    NaCl has been detected toward the circumstellar envelope of the post-AGB star CRL 2688 using the IRAM 30 m telescope, the first time this molecule has been identified in a source other than IRC +10216. The J=7-->6, 11-->10, 12-->11, and 18-->17 transitions of NaCl at 1, 2, and 3 mm have been observed, as well as the J=8-->7 line of the 37Cl isotopomer. The J=12-->11 line was also measured at the ARO 12 m telescope. An unsuccessful search was additionally conducted for AlCl toward CRL 2688, although in the process new transitions of NaCN were observed. Both NaCl and NaCN were found to be present in the AGB remnant wind, as suggested by their U-shaped line profiles, indicative of emission arising from an optically thin, extended shell-like source of radius ~10"-12". These data contrast with past results in IRC +10216, where the distribution of both molecules is confined to within a few arcseconds of the star. A high degree of excitation is required for the transitions observed for NaCl and NaCN; therefore, these two species likely arise in the region where the high-velocity outflow has collided with the remnant wind. Here the effects of shocks and clumping due to Rayleigh-Taylor instabilities have raised the densities and temperatures significantly. The shell source is thus likely to be clumpy and irregular. The chemistry producing the sodium compounds is consequently more complex than simple LTE formation. Abundances of NaCl and NaCN, relative to H2, are f~1.6×10-10 and ~5.2×10-9, respectively, while the upper limit to AlCl is f<2×10-9. These values differ substantially from those in IRC +10216, where AlCl has an abundance near 10-7. The NaCl observations additionally indicate a chlorine isotope ratio of 35Cl/37Cl=2.1+/-0.8 in CRL 2688, suggestive of s-process enhancement of chlorine 37.

  10. Analysis of cardiovascular responses to the H2S donors Na2S and NaHS in the rat

    PubMed Central

    Yoo, Daniel; Jupiter, Ryan C.; Pankey, Edward A.; Reddy, Vishwaradh G.; Edward, Justin A.; Swan, Kevin W.; Peak, Taylor C.; Mostany, Ricardo

    2015-01-01

    Hydrogen sulfide (H2S) is an endogenous gaseous molecule formed from L-cysteine in vascular tissue. In the present study, cardiovascular responses to the H2S donors Na2S and NaHS were investigated in the anesthetized rat. The intravenous injections of Na2S and NaHS 0.03–0.5 mg/kg produced dose-related decreases in systemic arterial pressure and heart rate, and at higher doses decreases in cardiac output, pulmonary arterial pressure, and systemic vascular resistance. H2S infusion studies show that decreases in systemic arterial pressure, heart rate, cardiac output, and systemic vascular resistance are well-maintained, and responses to Na2S are reversible. Decreases in heart rate were not blocked by atropine, suggesting that the bradycardia was independent of parasympathetic activation and was mediated by an effect on the sinus node. The decreases in systemic arterial pressure were not attenuated by hexamethonium, glybenclamide, Nw-nitro-l-arginine methyl ester hydrochloride, sodium meclofenamate, ODQ, miconazole, 5-hydroxydecanoate, or tetraethylammonium, suggesting that ATP-sensitive potassium channels, nitric oxide, arachidonic acid metabolites, cyclic GMP, p450 epoxygenase metabolites, or large conductance calcium-activated potassium channels are not involved in mediating hypotensive responses to the H2S donors in the rat and that responses are not centrally mediated. The present data indicate that decreases in systemic arterial pressure in response to the H2S donors can be mediated by decreases in vascular resistance and cardiac output and that the donors have an effect on the sinus node independent of the parasympathetic system. The present data indicate that the mechanism of the peripherally mediated hypotensive response to the H2S donors is uncertain in the intact rat. PMID:26071540

  11. Binding of benzocaine in batrachotoxin-modified Na+ channels. State- dependent interactions

    PubMed Central

    1994-01-01

    Hille (1977. Journal of General Physiology. 69:497-515) first proposed a modulated receptor hypothesis (MRH) to explain the action of benzocaine in voltage-gated Na+ channels. Using the MRH as a framework, we examined benzocaine binding in batrachotoxin (BTX)-modified Na+ channels under voltage-clamp conditions using either step or ramp command signals. We found that benzocaine binding is strongly voltage dependent. At -70 mV, the concentration of benzocaine that inhibits 50% of BTX-modified Na+ currents in GH3 cells (IC50) is 0.2 mM, whereas at +50 mV, the IC50 is 1.3 mM. Dose-response curves indicate that only one molecule of benzocaine is required to bind with one BTX-modified Na+ channel at -70 mV, whereas approximately two molecules are needed at +50 mV. Upon treatment with the inactivation modifier chloramine-T, the binding affinity of benzocaine is reduced significantly at -70 mV, probably as a result of the removal of the inactivated state of BTX- modified Na+ channels. The same treatment, however, enhances the binding affinity of cocaine near this voltage. External Na+ ions appear to have little effect on benzocaine binding, although they do affect cocaine binding. We conclude that two mechanisms underlie the action of local anesthetics in BTX-modified Na+ channels. Unlike open-channel blockers such as cocaine and bupivacaine, neutral benzocaine binds preferentially with BTX-modified Na+ channels in a closed state. Furthermore, benzocaine can be modified chemically so that it behaves like an open-channel blocker. This compound also elicits a use- dependent block in unmodified Na+ channels after repetitive depolarizations, whereas benzocaine does not. The implications of these findings for the MRH theory will be discussed. PMID:8195785

  12. Electrophysiological evidence for Na+-coupled bicarbonate transport in cultured rat hepatocytes.

    PubMed

    Fitz, J G; Persico, M; Scharschmidt, B F

    1989-03-01

    Recent observations suggest that hepatocytes exhibit basolateral electrogenic Na+-coupled HCO3- transport. In these studies, we have further investigated this transport mechanism in primary culture of rat hepatocytes using intracellular microelectrodes to measure membrane potential difference (PD) and the pH-sensitive fluorochrome 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein to measure intracellular pH (pHi). In balanced media containing 25 mM HCO3-, PD averaged -32.1 +/- 0.6 (SE) mV and pHi averaged 7.22 +/- 0.03. PD became more negative (hyperpolarized) when extracellular [HCO3-] was increased and less negative (depolarized) when extracellular HCO3- was decreased. Acute replacement of extracellular Na+ by choline also resulted in membrane depolarization of 18.0 +/- 1.6 mV, suggesting net transfer of negative charge. This decrease in PD upon Na+ removal was HCO3- -dependent, amiloride insensitive, and inhibited by the disulfonic stilbene 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS). PD also decreased upon acute exposure to SITS. The degree of depolarization seen with removal of Na+ or HCO3- correlated directly with resting PD (r = 0.81 and 0.95, respectively), suggesting a voltage-dependent mechanism. Removal of extracellular Na+ also decreased pHi to 7.06 +/- 0.02, and this acidification was decreased in the absence of HCO3- or in the presence of SITS or amiloride. These studies provide direct evidence for electrogenic Na+-coupled HCO3- transport in rat hepatocytes. Further, they suggest that it represents a major pathway for conductive movement of Na+ across the membrane and that it contributes, along with Na+-H+ exchange, to the intracellular acidification observed upon removal of extracellular Na+.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. [Synergistic effects of lysozyme with EDTA-2Na on antibacterial activity].

    PubMed

    Li, Xiao-man; Wang, Xiao-yan; Gao, Xue-jun

    2015-02-18

    To evaluate the synergistic antibacterial effects of lysozyme with ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) on Enterococcus faecalis (E. faecalis) and Porphyromonas endodontalis (P. endodontalis). E. faecalis and P. endodontalis were cultured and adjusted to 10(8) CFU/mL. Then 0.3, 0.5, 1, 2, 5, 10, 50, 100, 150 and 300 g/L of lysozyme were prepared with deionized water; and the lysozyme solutions were mixed with 0.5, 1.0, 2.0 g/L of EDTA-2Na, respectively. The bacteria and lysosome with/without EDTA-2Na interacted for 15 min, then water-soluble tetrazolium (WST) working solution was added and the activity of the bacteria was calculated by measuring optical densities at 450 nm and 630 nm with microplate spectrophotometer. Regarding the pure lysozyme from 0.5 g/L to 150 g/L, more E. faecalis and P. endodontalis were inhibited when the concentration of lysozyme was higher, especially for E. faecalis. There was synergistic effect of lysozyme with EDTA-2Na on antibacterial activity, which was related to the concentration of lysozyme. On E. faecalis, the antibacterial activity of lysozyme with EDTA-2Na was 1.2-3.7 folds than the pure lysozyme when the concentration of lysozyme was 0.5-50 g/L (P<0.05), and on P. endodontalis, the antibacterial activity of lysozyme with EDTA-2Na was 1.3-3.5 folds than the pure lysozyme when the concentration of lysozyme was 0.5-10 g/L (P<0.05). When the concentration of lysozyme was higher than 100 g/L, EDTA-2Na did not show synergistic effect on the antibacterial activity (P>0.05). For E. faecalis and P. endodontalis, a low concentration of lysozyme with EDTA-2Na showed significant synergistic antibacterial activity, while a high concentration of lysozyme with EDTA-2Na did not.

  14. Fluorine-18 NaF PET imaging of child abuse.

    PubMed

    Drubach, Laura A; Sapp, Mark V; Laffin, Stephen; Kleinman, Paul K

    2008-07-01

    We describe the use of 18F-NaF positron emission tomography (PET) whole-body imaging for the evaluation of skeletal trauma in a case of suspected child abuse. To our knowledge, 18F NaF PET has not been used in the past for the evaluation of child abuse. In our patient, this technique detected all sites of trauma shown by initial and follow-up skeletal surveys, including bilateral metaphyseal fractures of the proximal humeri. Fluorine-18 NaF PET has potential advantage over Tc-99m-labeled methylene diphosphonate (MDP) based upon superior image contrast and spatial resolution.

  15. Projectile n distributions following charge transfer of Ar+ and Na+ in a Na Rydberg target

    NASA Astrophysics Data System (ADS)

    MacAdam, K. B.; Gray, L. G.; Rolfes, R. G.

    1990-11-01

    The n distributions produced by charge transfer of Ar+ and Na+ ions in a target of Na(nl) Rydberg atoms were extensively measured at intermediate velocities. The 60-2100-eV ions bombarded a laser-excited atomic-beam target. The projectiles were neutralized by capture into Rydberg states of Ar and Na and were analyzed by field ionization in an inhomogeneous-field detector whose response over states and energies was carefully mapped. The choice of initially prepared Na states, 24d, 25s, 28d, 29s, 33d, and 34s, allowed a comparison of l=0 and >=2 targets at nearly equal binding energies over a range of reduced velocity v~=0.187 to 1.95. Capture populates m sublevels broadly, not merely m~=0. Overlapping contributions from adiabatic and diabatic modes of field ionization were accommodated in the analysis, which used a maximum-entropy-principle parametric form to fit the observed final-state distributions. The peak of the distributions, nmax, shifts upward from a value less than the initial state ni to a value one to three units higher than ni at v~ between 0.7 and 0.9 and ultimately shifts downward below ni as v~ is further increased. The distributions become significantly sharper where the maximum upward shift occurs. Two ratios were defined to express the widths of final-state distributions in relative terms, one measuring the spread of orbital kinetic energy and the other the spread of Bohr-orbit velocity. By these ratios a universal behavior over energies, states, and projectile species is observed, and small differences between l=0 and >=2 targets may be seen. A theoretical understanding of the present results, which span velocities where both molecular and perturbative theories are normally used, will require a quantal formulation that models the free-ranging response that is a hallmark of the high-quantum-number limit.

  16. Na+/H+ antiport is essential for Yersinia pestis virulence.

    PubMed

    Minato, Yusuke; Ghosh, Amit; Faulkner, Wyatt J; Lind, Erin J; Schesser Bartra, Sara; Plano, Gregory V; Jarrett, Clayton O; Hinnebusch, B Joseph; Winogrodzki, Judith; Dibrov, Pavel; Häse, Claudia C

    2013-09-01

    Na(+)/H(+) antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na(+)/H(+) antiport in Yersinia pestis virulence and found that Y. pestis strains lacking the major Na(+)/H(+) antiporters, NhaA and NhaB, are completely attenuated in an in vivo model of plague. The Y. pestis derivative strain lacking the nhaA and nhaB genes showed markedly decreased survival in blood and blood serum ex vivo. Complementation of either nhaA or nhaB in trans restored the survival of the Y. pestis nhaA nhaB double deletion mutant in blood. The nhaA nhaB double deletion mutant also showed inhibited growth in an artificial serum medium, Opti-MEM, and a rich LB-based medium with Na(+) levels and pH values similar to those for blood. Taken together, these data strongly suggest that intact Na(+)/H(+) antiport is indispensable for the survival of Y. pestis in the bloodstreams of infected animals and thus might be regarded as a promising noncanonical drug target for infections caused by Y. pestis and possibly for those caused by other blood-borne bacterial pathogens.

  17. Controlled thermal decomposition of NaSi to derive silicon clathrate compounds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Horie, Hiro-omi; Kikudome, Takashi; Teramura, Kyosuke

    Formation conditions of two types of sodium containing silicon clathrate compounds were determined by the controlled thermal decomposition of sodium monosilicide NaSi under vacuum. The decomposition began at 360 deg. C. Much higher decomposition temperatures and the presence of sodium metal vapor were favorable for the formation of type I clathrate compound Na{sub 8}Si{sub 46}. Type II clathrate compound Na{sub x}Si{sub 136} was obtained as a single phase at a decomposition temperature <440 deg. C under the condition without sodium metal vapor. The type I clathrate compound was decomposed to crystalline Si above 520 deg. C. The type II clathratemore » compound was thermally more stable, and retained at least up to 550 deg. C in vacuum. - Graphical Abstract: The optimal condition to prepare type II silicon clathrate Na{sub x}Si{sub 136} with minimal contamination of the type I phase is proposed. The starting NaSi should be thermally decomposed below 440 deg. C, and the rapid removal of Na vapor evolved is essentially important.« less

  18. A Quaternary Sodium Superionic Conductor - Na 10.8Sn 1.9PS 11.8

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yu, Zhaoxin; Shang, Shun -Li; Gao, Yue

    Sulfide-based Na-ion conductors are promising candidates as solid-state electrolytes (SSEs) for fabrication of solid-state Na-ion batteries (NIBs) because of their high ionic conductivities and low grain boundary resistance. Currently, most of the sulfide-based Na-ion conductors with high conductivities are focused on Na 3PS 4 phases and its derivatives. It is desirable to develop Na-ion conductors with new composition and crystal structure to achieve superior ionic conductivities. Here we report a new quaternary Na-ion conductor, Na 10.8Sn 1.9PS 11.8, exhibiting a high ionic conductivity of 0.67 mS cm –1 at 25 °C. This high ionic conductivity originates from the presence ofmore » a large number of intrinsic Na-vacancies and three-dimensional Na-ion conduction pathways, which has been confirmed by single-crystal X-ray diffraction and first-principles calculations. In conclusion, the Na 10.8Sn 1.9PS 11.8 phase is further evaluated as an electrolyte in a Na-Sn alloy/TiS 2 battery, demonstrating its potential application in all-solid-state NIBs.« less

  19. A Quaternary Sodium Superionic Conductor - Na 10.8Sn 1.9PS 11.8

    DOE PAGES

    Yu, Zhaoxin; Shang, Shun -Li; Gao, Yue; ...

    2018-01-31

    Sulfide-based Na-ion conductors are promising candidates as solid-state electrolytes (SSEs) for fabrication of solid-state Na-ion batteries (NIBs) because of their high ionic conductivities and low grain boundary resistance. Currently, most of the sulfide-based Na-ion conductors with high conductivities are focused on Na 3PS 4 phases and its derivatives. It is desirable to develop Na-ion conductors with new composition and crystal structure to achieve superior ionic conductivities. Here we report a new quaternary Na-ion conductor, Na 10.8Sn 1.9PS 11.8, exhibiting a high ionic conductivity of 0.67 mS cm –1 at 25 °C. This high ionic conductivity originates from the presence ofmore » a large number of intrinsic Na-vacancies and three-dimensional Na-ion conduction pathways, which has been confirmed by single-crystal X-ray diffraction and first-principles calculations. In conclusion, the Na 10.8Sn 1.9PS 11.8 phase is further evaluated as an electrolyte in a Na-Sn alloy/TiS 2 battery, demonstrating its potential application in all-solid-state NIBs.« less

  20. A Sensor Based on LiCl/NaA Zeolite Composites for Effective Humidity Sensing.

    PubMed

    Zhang, Ying; Xiang, Hongyu; Sun, Liang; Xie, Qiuhong; Liu, Man; Chen, Yu; Ruan, Shengping

    2018-03-01

    LiCl/NaA zeolite composites were successfully prepared by doping 1 wt%, 2 wt%, 5 wt%, and 8 wt% of LiCl into NaA zeolite. The humidity sensing properties of LiCl/NaA composites were investigated among 11% 95% relative humidity (RH). The LiCl/NaA composites exhibited better humidity sensing properties than pure NaA zeolite. The sensor made by 2 wt% Li-doped NaA zeolite possesses the best linearly in the whole RH. These results demonstrate that the LiCl/NaA composites have the potential application in humidity sensing.

  1. Quantifying Hydrological Ecosystem Services of Various Land Covers and Uses on Small Experimental Catchments within the Panama Canal Watershed: The Agua Salud Project

    NASA Astrophysics Data System (ADS)

    Crouch, T. D.; Ogden, F. L.; Agua Salud Project

    2011-12-01

    As a part of the Agua Salud Project, a baseline characterization of hydrologic processes on the small catchment scale (~0.24 to 2.0 km2) is assessed across different land uses and covers typical to rural Panama. The land covers being monitored include a mature secondary forest, a disturbed catchment with a mosaic of various aged secondary growth and agricultural use, an active pasture and a monoculture invasive grass site as experimental controls, and two treated catchments that were recently abandoned pastures converted to teak and native species timber plantations. The catchments are found within Panama's protected Soberania National Park and the adjacent headwaters of the Agua Salud and Mendoza Rivers, all part of the greater Panama Canal Watershed. Using hydrological data from the first two and a half years of the project, three main ecosystem services are observed. The forested area exhibited lower storm event peaks, decreased flashiness, and greater stream flow during the dry season compared to the disturbed mosaic site. Lower hydrograph peaks and flashiness mitigate the risk of substantial flood damage during the major flood events generally seen in Panama between October and December. The mature forest (1.35 km2) catchment has shown lower average flood peaks in comparison to the disturbed site. For storm peaks less than 6 mm/hr, flood peaks are on average 51% lower. For storm peaks greater than 6 mm/hr, flood peaks are approximately 40% lower. In 1998, draft restrictions were imposed in the Panama Canal because of a deficit of dry season water after an El Niño-Southern Oscillation resulted in decreased wet season rainfall. The water that is available during the end of the dry season has the potential to insure the full operation of the Canal during El Niño drought years. Toward the end of the dry season (March through May) our data shows that roughly 34% more water was available during a relatively dry year with respect to antecedent wet season rainfall

  2. The role of Na-Ca exchange current in the cardiac action potential.

    PubMed

    Janvier, N C; Boyett, M R

    1996-07-01

    Since 1981, when Mullins published his provocative book proposing that the Na-Ca exchanger is electrogenic, it has been shown, first by computer simulation by Noble and later by experiment by various investigators, that inward iNaCa triggered by the Ca2+ transient is responsible for the low plateau of the atrial action potential and contributes to the high plateau of the ventricular action potential. Reduction or complete block of inward iNaCa by buffering intracellular Ca2+ with EGTA or BAPTA, by blocking SR Ca2+ release or by substituting extracellular Na+ with Li+ can result in a shortening of the action potential. The effect of block of outward iNaCa or complete block of both inward and outward iNaCa on the action potential has not been investigated experimentally, because of the lack of a suitable blocker, and remains a goal for the future. An increase in the intracellular Na+ concentration (after the application of cardiac glycoside or an increase in heart rate) or an increase in extracellular Ca2+ are believed to lead to an outward shift in iNaCa at plateau potentials and a shortening of the action potential. Changes in the Ca2+ transient are expected to result in changes in inward iNaCa and thus the action potential. This may explain the shortening of the premature action potential as well as the prolongation of the action potential when a muscle is allowed to shorten during the action potential. Inward iNaCa may play an important role in both normal and abnormal pacemaker activity in the heart.

  3. Maintaining K+ balance on the low-Na+, high-K+ diet

    PubMed Central

    Cornelius, Ryan J.; Wang, Bangchen; Wang-France, Jun

    2016-01-01

    A low-Na+, high-K+ diet (LNaHK) is considered a healthier alternative to the “Western” high-Na+ diet. Because the mechanism for K+ secretion involves Na+ reabsorptive exchange for secreted K+ in the distal nephron, it is not understood how K+ is eliminated with such low Na+ intake. Animals on a LNaHK diet produce an alkaline load, high urinary flows, and markedly elevated plasma ANG II and aldosterone levels to maintain their K+ balance. Recent studies have revealed a potential mechanism involving the actions of alkalosis, urinary flow, elevated ANG II, and aldosterone on two types of K+ channels, renal outer medullary K+ and large-conductance K+ channels, located in principal and intercalated cells. Here, we review these recent advances. PMID:26739887

  4. Altered erythrocyte Na-K pump in anorectic patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pasquali, R.; Strocchi, E.; Malini, P.

    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)more » 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.« less

  5. NA61/SHINE facility at the CERN SPS: beams and detector system

    NASA Astrophysics Data System (ADS)

    Abgrall, N.; Andreeva, O.; Aduszkiewicz, A.; Ali, Y.; Anticic, T.; Antoniou, N.; Baatar, B.; Bay, F.; Blondel, A.; Blumer, J.; Bogomilov, M.; Bogusz, M.; Bravar, A.; Brzychczyk, J.; Bunyatov, S. A.; Christakoglou, P.; Cirkovic, M.; Czopowicz, T.; Davis, N.; Debieux, S.; Dembinski, H.; Diakonos, F.; Di Luise, S.; Dominik, W.; Drozhzhova, T.; Dumarchez, J.; Dynowski, K.; Engel, R.; Efthymiopoulos, I.; Ereditato, A.; Fabich, A.; Feofilov, G. A.; Fodor, Z.; Fulop, A.; Gaździcki, M.; Golubeva, M.; Grebieszkow, K.; Grzeszczuk, A.; Guber, F.; Haesler, A.; Hasegawa, T.; Hierholzer, M.; Idczak, R.; Igolkin, S.; Ivashkin, A.; Jokovic, D.; Kadija, K.; Kapoyannis, A.; Kaptur, E.; Kielczewska, D.; Kirejczyk, M.; Kisiel, J.; Kiss, T.; Kleinfelder, S.; Kobayashi, T.; Kolesnikov, V. I.; Kolev, D.; Kondratiev, V. P.; Korzenev, A.; Koversarski, P.; Kowalski, S.; Krasnoperov, A.; Kurepin, A.; Larsen, D.; Laszlo, A.; Lyubushkin, V. V.; Maćkowiak-Pawłowska, M.; Majka, Z.; Maksiak, B.; Malakhov, A. I.; Maletic, D.; Manglunki, D.; Manic, D.; Marchionni, A.; Marcinek, A.; Marin, V.; Marton, K.; Mathes, H.-J.; Matulewicz, T.; Matveev, V.; Melkumov, G. L.; Messina, M.; Mrówczyński, St.; Murphy, S.; Nakadaira, T.; Nirkko, M.; Nishikawa, K.; Palczewski, T.; Palla, G.; Panagiotou, A. D.; Paul, T.; Peryt, W.; Petukhov, O.; Pistillo, C.; Płaneta, R.; Pluta, J.; Popov, B. A.; Posiadala, M.; Puławski, S.; Puzovic, J.; Rauch, W.; Ravonel, M.; Redij, A.; Renfordt, R.; Richter-Was, E.; Robert, A.; Röhrich, D.; Rondio, E.; Rossi, B.; Roth, M.; Rubbia, A.; Rustamov, A.; Rybczyński, M.; Sadovsky, A.; Sakashita, K.; Savic, M.; Schmidt, K.; Sekiguchi, T.; Seyboth, P.; Sgalaberna, D.; Shibata, M.; Sipos, R.; Skrzypczak, E.; Słodkowski, M.; Sosin, Z.; Staszel, P.; Stefanek, G.; Stepaniak, J.; Stroebele, H.; Susa, T.; Szuba, M.; Tada, M.; Tereshchenko, V.; Tolyhi, T.; Tsenov, R.; Turko, L.; Ulrich, R.; Unger, M.; Vassiliou, M.; Veberic, D.; Vechernin, V. V.; Vesztergombi, G.; Vinogradov, L.; Wilczek, A.; Włodarczyk, Z.; Wojtaszek-Szwarz, A.; Wyszyński, O.; Zambelli, L.; Zipper, W.

    2014-06-01

    NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) is a multi-purpose experimental facility to study hadron production in hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron. It recorded the first physics data with hadron beams in 2009 and with ion beams (secondary 7Be beams) in 2011. NA61/SHINE has greatly profited from the long development of the CERN proton and ion sources and the accelerator chain as well as the H2 beamline of the CERN North Area. The latter has recently been modified to also serve as a fragment separator as needed to produce the Be beams for NA61/SHINE. Numerous components of the NA61/SHINE set-up were inherited from its predecessors, in particular, the last one, the NA49 experiment. Important new detectors and upgrades of the legacy equipment were introduced by the NA61/SHINE Collaboration. This paper describes the state of the NA61/SHINE facility — the beams and the detector system — before the CERN Long Shutdown I, which started in March 2013.

  6. Mechanism of Na accumulation at extended defects in Si from first-principles

    NASA Astrophysics Data System (ADS)

    Park, Ji-Sang; Chan, Maria K. Y.

    2018-04-01

    Sodium (Na) impurities in silicon solar cells are considered to play an important role in potential-induced degradation (PID), a significant cause of solar cell degradation and failure. Shorting due to Na accumulation at extended defects has been suggested as a culprit for PID. However, it is not clear how the extended defects are decorated by Na impurities. Using first-principles density functional theory calculations, we find that Na impurities segregate from the bulk into extended defects such as intrinsic stacking faults and Σ3 (111) grain boundaries. The energy barrier required for Na to escape from the extended defects is substantial and similar to the sum of the barrier energy in bulk Si (1.1-1.2 eV) and the segregation energy to the stacking fault (˜0.7 eV). Surprisingly, the migration barrier for Na diffusion within the extended defects is even higher than the energy barrier for escaping. The results suggest that the extended defects likely accumulate Na as the impurities segregate to the defects from the bulk, rather than because of migration through the extended defects.

  7. Uso de modelos mecânicos em curso informal de astronomia para deficientes visuais. Resgate de uma experiência

    NASA Astrophysics Data System (ADS)

    Tavares, E. T., Jr.; Klafke, J. C.

    2003-08-01

    O presente trabalho propõe-se a resgatar uma experiência que teve lugar no Planetário de São Paulo nos anos 60. Em 1962, o Sr. Acácio, então com 37 anos, deficiente visual desde os 27, passou a assistir às aulas ministradas pelo Prof. Aristóteles Orsini aos integrantes do corpo de servidores do Planetário. O Sr. Acácio era o único deficiente da turma e, embora possuísse conhecimentos básicos e relativamente avançados de matemática, enfrentava dificuldades na compreensão e acompanhamento da exposição, como também em estudos posteriores. Com o intuito de auxiliá-lo na superação desses problemas, o Prof. Orsini solicitou a construção de modelos mecânicos que, através do sentido do tato, permitissem o acompanhamento das aulas e a transposição do modelo para o "constructo" mental. Essa prática mostrou-se tão eficaz que facilitou sobejamente o aprendizado da matéria pelo sujeito. O Sr. Acácio passou a integrar o corpo de professores do Planetário/Escola Municipal de Astrofísica, tendo ficado responsável pelo curso de "Introdução à Astronomia" por vários anos. Além disso, a experiência foi tão bem sucedida que alguns dos modelos tiveram seus elementos constitutivos pintados diferencialmente para serem utilizados em cursos regulares do Planetário, tornando-se parte integrante do conjunto de recursos didáticos da instituição. É pensando nessa eficácia, tanto em seu objetivo original permitir o aprendizado de um deficiente visual quanto no subsidiário recurso didático sistemático da instituição que decidimos resgatar essa experiência. Estribados nela, acreditamos ser extremamente produtivo, em termos educacionais, o aperfeiçoamento dos modelos originais, agora resgatados e restaurados, e a criação de outros que pudessem ser utilizados no ensino dessa ciência a deficientes visuais.

  8. Effect of azathioprine on Na(+)/H(+) exchanger activity in dendritic cells.

    PubMed

    Bhandaru, Madhuri; Pasham, Venkanna; Yang, Wenting; Bobbala, Diwakar; Rotte, Anand; Lang, Florian

    2012-01-01

    Azathioprine is a powerful immunosuppressive drug, which is partially effective by interfering with the maturation and function of dendritic cells (DCs), antigen-presenting cells linking innate and adaptive immunity. DCs are stimulated by bacterial lipopolysaccharides (LPS), which trigger the formation of reactive oxygen species (ROS), paralleled by activation of the Na(+)/H(+) exchanger. The carrier is involved in the regulation of cytosolic pH, cell volume and migration. The present study explored whether azathioprine influences Na(+)/H(+) exchanger activity in DCs. DCs were isolated from murine bone marrow, cytosolic pH (pH(i)) was estimated utilizing 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF-AM) fluorescence, Na(+)/H(+) exchanger activity from the Na(+)-dependent realkalinization following an ammonium pulse, cell volume from forward scatter in FACS analysis, ROS production from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence, TNFα release utilizing ELISA, and migration utilizing transwell migration assays. Exposure of DCs to lipopolysaccharide (LPS, 1 μg/ml) led to a transient increase of Na(+)/H(+) exchanger activity, an effect paralleled by ROS formation, increased cell volume, TNFα production and stimulated migration. Azathioprine (10 μM) did not significantly alter the Na(+)/H(+) exchanger activity, cell volume and ROS formation prior to LPS exposure but significantly blunted the LPS-induced stimulation of Na(+)/H(+) exchanger activity, ROS formation, cell swelling, TNFα production and cell migration. In conclusion, azathioprine interferes with the activation of dendritic cell Na(+)/H(+) exchanger by bacterial lipopolysaccharides, an effect likely participating in the anti-inflammatory action of the drug. Copyright © 2012 S. Karger AG, Basel.

  9. Crystal structure and europium luminescence of NaMgH3-xFx

    NASA Astrophysics Data System (ADS)

    Pflug, Christian; Franz, Alexandra; Kohlmann, Holger

    2018-02-01

    The solid solution series NaMgH3-xFx (x = 0, 0.5, 1, 1.5, 2, 2.5, 3) was synthesized by solid-state reactions under hydrogen gas pressure from binary ionic hydrides, fluorides and magnesium. Rietveld refinement based on X-ray powder diffraction data revealed the GdFeO3-structure type for all compounds and a trend of lattice parameters according to Vegard's law. The anion distribution in NaMgD2F and NaMgD1.5F1.5 was found to be statistical by Rietveld refinement based on neutron powder diffraction data. Photoluminescence measurements on europium(II) substituted NaMgH3-xFx revealed a strong red shift of the emission wavelength (λem = 665 nm for NaMgH2F:Eu) in comparison to violet emitting NaMgF3:Eu.

  10. (Na, K)NbO3-Based Ceramics for Self-Powered Energy Harvesting Applications.

    PubMed

    Kim, Jinhwan; Koh, Jung-Hyuk

    2015-03-01

    Self-powered energy harvesting technologies have been intensively investigated by employ- ing Pb-free piezoelectric materials. One such Pb-free piezoelectric material, the ceramic 0.97(Na0.5K0.5)NbO3-0.03(Bi0.5Na0.5)TiO3, was prepared by employing the conventional mixed oxide method. 0.97(Na0.5K0.5)NbO3-0.03(Bi0.5Na0.5)TiO3 ceramics were prepared and the effect of sintering temperature on the microstructure, piezoelectric and ferroelectric properties were system- atically investigated for energy harvesting applications. The crystal structure of 0.97(Na0.5K0.5)NbO3- 0.03(Bi0.5Na0.5) TiO3 Pb-free piezoelectric ceramics, sintered at temperatures between 1080 °C and 1160 °C, was examined by X-ray diffraction analysis. The dielectric properties of 0.97(Na0.5K0.5)NbO3-0.03(Bi0.5Na0.5)TiO3 ceramics were measured from 1 kHz to 1 MHz for the various sintering temperatures. We expect that optimization of sintering parameters can improve the piezoelectric and ferroelectric properties of 0.97 (Na0.5K0.5)NbO3-0.03(Bi0.5Na0.5)TiO3 ceramics for energy harvesting.

  11. Effect of Ca(OH)2, NaCl, and Na2SO4 on the corrosion and electrochemical behavior of rebar

    NASA Astrophysics Data System (ADS)

    Jin, Zuquan; Zhao, Xia; Zhao, Tiejun; Hou, Baorong; Liu, Ying

    2017-05-01

    The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior of rebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy (EIS) plots of rebar in Ca(OH)2 solution and cement grout, including NaCl and Na2SO4 as aggressive salts, were measured for diff erent immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diff usion rate. When Na2SO4 and NaCl were added to Ca(OH)2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher pH of the corroding solution.

  12. Ion-Transport Design for High-Performance Na+-Based Electrochromics.

    PubMed

    Li, Ran; Li, Kerui; Wang, Gang; Li, Lei; Zhang, Qiangqiang; Yan, Jinhui; Chen, Yao; Zhang, Qinghong; Hou, Chengyi; Li, Yaogang; Wang, Hongzhi

    2018-04-24

    Sodium ion (Na + )-based electrochemical systems have been extensively investigated in batteries and supercapacitors and also can be quality candidates for electrochromic (EC) devices. However, poor diffusion kinetics and severe EC performance degradation occur during the intercalation/deintercalation processes because the ionic radii of Na + are larger than those of conventional intercalation ions. Here, through intentional design of ion-transport channels in metal-organic frameworks (MOFs), Na + serves as an efficient intercalation ion for incorporation into a nanostructured electrode with a high diffusion coefficient of approximately 10 -8 cm 2 s -1 . As a result, the well-designed MOF-based EC device demonstrates desirable Na + EC performance, including fast switching speed, multicolor switching, and high stability. A smart "quick response code" display is fabricated using a mask-free laser writing method for application in the "Internet of Things". In addition, the concept of ion transport pathway design can be widely adopted for fabricating high-performance ion intercalation materials and devices for consumer electronics.

  13. Negative pressure of the environmental air in the cleaning area of the materials and sterilization center: a systematic review.

    PubMed

    Ciofi-Silva, Caroline Lopes; Hansen, Lisbeth Lima; Almeida, Alda Graciele Claudio Dos Santos; Kawagoe, Julia Yaeko; Padoveze, Maria Clara; Graziano, Kazuko Uchikawa

    2016-09-01

    to analyze the scientific evidence on aerosols generated during cleaning activities of health products in the Central Service Department (CSD) and the impact of the negative pressure of the ambient air in the cleaning area to control the dispersion of aerosols to adjacent areas. for this literature systematic review the following searches were done: search guidelines, manuals or national and international technical standards given by experts; search in the portal and databases PubMed, Scopus, CINAHL and Web of Science; and a manual search of scientific articles. the five technical documents reviewed recommend that the CSD cleaning area should have a negative differential ambient air pressure, but scientific articles on the impact of this intervention were not found. The four articles included talked about aerosols formed after the use of a ultrasonic cleaner (an increased in the contamination especially during use) and pressurized water jet (formation of smaller aerosols 5μm). In a study, the aerosols formed from contaminated the hot tap water with Legionella pneumophila were evaluated. there is evidence of aerosol formation during cleanup activities in CSD. Studies on occupational diseases of respiratory origin of workers who work in CSD should be performed. analisar as evidências científicas sobre aerossóis gerados durante atividades de limpeza dos produtos para saúde no Centro de Material e Esterilização (CME) e o impacto da pressão negativa do ar ambiente na área de limpeza para controle da dispersão de aerossóis para áreas adjacentes. para essa revisão sistemática de literatura foram realizadas: busca de diretrizes, manuais ou normas técnicas nacionais e internacionais indicadas por especialistas; busca no portal e bases de dados PUBMED, SCOPUS, Cinahl e Web of Science; e busca manual de artigos científicos. Os cinco documentos técnicos analisados preconizam que na área de limpeza do CME haja diferencial negativo de pressão do ar ambiente

  14. Solvation of Na^+ in water from first-principles molecular dynamics

    NASA Astrophysics Data System (ADS)

    White, J. A.; Schwegler, E.; Galli, G.; Gygi, F.

    2000-03-01

    We have carried out ab initio molecular dynamics (MD) simulations of the Na^+ ion in water with an MD cell containing a single alkali ion and 53 water molecules. The electron-electron and electron-ion interactions were modeled by density functional theory with a generalized gradient approximation for the exchange-correlation functional. The computed radial distribution functions, coordination numbers, and angular distributions are consistent with available experimental data. The first solvation shell contains 5.2±0.6 water molecules, with some waters occasionally exchanging with those of the second shell. The computed Na^+ hydration number is larger than that from calculations for water clusters surrounding an Na^+ ion, but is consistent with that derived from x-ray measurements. Our results also indicate that the first hydration shell is better defined for Na^+ than for K^+ [1], as indicated by the first minimum in the Na-O pair distribution function. [1] L.M. Ramaniah, M. Bernasconi, and M. Parrinello, J. Chem. Phys. 111, 1587 (1999). This work was performed for DOE under contract W-7405-ENG-48.

  15. Optically stimulated luminescence in doped NaCl

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gaikwad, S. U., E-mail: gaikwadsonali09@yahoo.com; Patil, R. R.; Kulkarni, M. S.

    NaCl:Ca,Cu,P NaCl:Mg,Cu,P OSL phosphors are synthesized. Intense OSL is observed in these samples which is 14 times more than Al{sub 2}O{sub 3}:C. Same samples coated with PVA (poly vinyl actetae) polymer also show similar OSL properties and these coated samples are found to be less susceptible to the moisture due to protected layer of hydrophobic polymer. These coated samples may be useful as OSL dosimetersdue to high sensitivity and less or no susceptibility to moisture.

  16. Toward Triplet Ground State NaLi Molecules

    NASA Astrophysics Data System (ADS)

    Ebadi, Sepehr; Jamison, Alan; Rvachov, Timur; Jing, Li; Son, Hyungmok; Jiang, Yijun; Zwierlein, Martin; Ketterle, Wolfgang

    2016-05-01

    The NaLi molecule is expected to have a long lifetime in the triplet ground-state due to its fermionic nature, large rotational constant, and weak spin-orbit coupling. The triplet state has both electric and magnetic dipole moments, affording unique opportunities in quantum simulation and ultracold chemistry. We have mapped the excited state NaLi triplet potential by means of photoassociation spectroscopy. We report on this and our further progress toward the creation of the triplet ground-state molecules using STIRAP. NSF, ARO-MURI, Samsung, NSERC.

  17. Design of a Mechanical NaK Pump for Fission Space Power

    NASA Technical Reports Server (NTRS)

    Mireles, Omar R.; Bradley, David E.; Godfroy, Thomas

    2011-01-01

    Alkali liquid metal cooled fission reactor concepts are under development for spaceflight power requirements. One such concept utilizes a sodium-potassium eutectic (NaK) as the primary loop working fluid, which has specific pumping requirements. Traditionally, electromagnetic linear induction pumps have been used to provide the required flow and pressure head conditions for NaK systems but they can be limited in performance, efficiency, and number of available vendors. The objective of the project was to develop a mechanical NaK centrifugal pump that takes advantages of technology advances not available in previous liquid metal mechanical pump designs. This paper details the design, build, and performance test of a mechanical NaK pump developed at NASA Marshall Space Flight Center. The pump was designed to meet reactor cooling requirements using commercially available components modified for high temperature NaK service.

  18. Interactions among DIV voltage-sensor movement, fast inactivation, and resurgent Na current induced by the NaVβ4 open-channel blocking peptide

    PubMed Central

    Lewis, Amanda H.

    2013-01-01

    Resurgent Na current flows as voltage-gated Na channels recover through open states from block by an endogenous open-channel blocking protein, such as the NaVβ4 subunit. The open-channel blocker and fast-inactivation gate apparently compete directly, as slowing the onset of fast inactivation increases resurgent currents by favoring binding of the blocker. Here, we tested whether open-channel block is also sensitive to deployment of the DIV voltage sensor, which facilitates fast inactivation. We expressed NaV1.4 channels in HEK293t cells and assessed block by a free peptide replicating the cytoplasmic tail of NaVβ4 (the “β4 peptide”). Macroscopic fast inactivation was disrupted by mutations of DIS6 (L443C/A444W; “CW” channels), which reduce fast-inactivation gate binding, and/or by the site-3 toxin ATX-II, which interferes with DIV movement. In wild-type channels, the β4 peptide competed poorly with fast inactivation, but block was enhanced by ATX. With the CW mutation, large peptide-induced resurgent currents were present even without ATX, consistent with increased open-channel block upon depolarization and slower deactivation after blocker unbinding upon repolarization. The addition of ATX greatly increased transient current amplitudes and further enlarged resurgent currents, suggesting that pore access by the blocker is actually decreased by full deployment of the DIV voltage sensor. ATX accelerated recovery from block at hyperpolarized potentials, however, suggesting that the peptide unbinds more readily when DIV voltage-sensor deployment is disrupted. These results are consistent with two open states in Na channels, dependent on the DIV voltage-sensor position, which differ in affinity for the blocking protein. PMID:23940261

  19. HARP and NA61 (SHINE) hadron production experiments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Popov, Boris A.

    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 inputmore » for validation and tuning of hadroproduction models in Monte-Carlo generators.« less

  20. The puzzling interpretation of NIR indices: The case of NaI2.21

    NASA Astrophysics Data System (ADS)

    Röck, B.; Vazdekis, A.; La Barbera, F.; Peletier, R. F.; Knapen, J. H.; Allende-Prieto, C.; Aguado, D. S.

    2017-11-01

    We present a detailed study of the Na I line strength index centred in the K band at 22 100 Å (NaI2.21 hereafter) relying on different samples of early-type galaxies. Consistent with previous studies, we find that the observed line strength indices cannot be fit by state-of-the-art scaled-solar stellar population models, even using our newly developed models in the near infrared (NIR). The models clearly underestimate the large NaI2.21 values measured for most early-type galaxies. However, we develop an Na-enhanced version of our newly developed models in the NIR, which - together with the effect of a bottom-heavy initial mass function - yield NaI2.21 indices in the range of the observations. Therefore, we suggest a scenario in which the combined effect of [Na/Fe] enhancement and a bottom-heavy initial mass function are mainly responsible for the large NaI2.21 indices observed for most early-type galaxies. To a smaller extent, also [C/Fe] enhancement might contribute to the large observed NaI2.21 values.

  1. On the origin of high ionic conductivity in Na-doped SrSiO 3

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chien, Po-Hsiu; Jee, Youngseok; Huang, Chen

    Understanding the local structure and ion dynamics is at the heart of ion conductor research. This paper reports on high-resolution solid-state 29Si, 23Na, and 17O NMR investigation of the structure, chemical composition, and ion dynamics of a newly discovered fast ion conductor, Na-doped SrSiO 3, which exhibited a much higher ionic conductivity than most of current oxide ion conductors. Quantitative analyses reveal that with a small dose (<10 mol%) of Na, the doped Na integrates into the SrSiO 3 structure to form Na xSr 1-xSiO 3-0.5x, and with >10 mol% Na doping, phase separation occurs, leading to the formation ofmore » an amorphous phase β-Na 2Si 2O 5 and a crystalline Sr-rich phase. Variable-temperature 23Na and 17O magic-angle-spinning NMR up to 618 °C have shown significant changes in Na ion dynamics at high temperatures but little oxide ion motion, suggesting that Na ions are responsible for the observed high ionic conductivity. In addition, β-Na 2Si 2O 5 starts to crystallize at temperatures higher than 480 °C with prolonged heating, resulting in reduction in Na+ motion, and thus degradation of ionic conductivity. This study has contributed critical evidence to the understanding of ionic conduction in Na-doped SrSiO 3 and demonstrated that multinuclear high-resolution and high-temperature solid-state NMR is a uniquely useful tool for investigating ion conductors at their operating conditions.« less

  2. On the origin of high ionic conductivity in Na-doped SrSiO 3

    DOE PAGES

    Chien, Po-Hsiu; Jee, Youngseok; Huang, Chen; ...

    2016-02-17

    Understanding the local structure and ion dynamics is at the heart of ion conductor research. This paper reports on high-resolution solid-state 29Si, 23Na, and 17O NMR investigation of the structure, chemical composition, and ion dynamics of a newly discovered fast ion conductor, Na-doped SrSiO 3, which exhibited a much higher ionic conductivity than most of current oxide ion conductors. Quantitative analyses reveal that with a small dose (<10 mol%) of Na, the doped Na integrates into the SrSiO 3 structure to form Na xSr 1-xSiO 3-0.5x, and with >10 mol% Na doping, phase separation occurs, leading to the formation ofmore » an amorphous phase β-Na 2Si 2O 5 and a crystalline Sr-rich phase. Variable-temperature 23Na and 17O magic-angle-spinning NMR up to 618 °C have shown significant changes in Na ion dynamics at high temperatures but little oxide ion motion, suggesting that Na ions are responsible for the observed high ionic conductivity. In addition, β-Na 2Si 2O 5 starts to crystallize at temperatures higher than 480 °C with prolonged heating, resulting in reduction in Na+ motion, and thus degradation of ionic conductivity. This study has contributed critical evidence to the understanding of ionic conduction in Na-doped SrSiO 3 and demonstrated that multinuclear high-resolution and high-temperature solid-state NMR is a uniquely useful tool for investigating ion conductors at their operating conditions.« less

  3. Molecular characterization of the Na+/H+-antiporter NhaA from Salmonella Typhimurium.

    PubMed

    Lentes, Christopher J; Mir, Syed H; Boehm, Marc; Ganea, Constanta; Fendler, Klaus; Hunte, Carola

    2014-01-01

    Na+/H+ antiporters are integral membrane proteins that are present in almost every cell and in every kingdom of life. They are essential for the regulation of intracellular pH-value, Na+-concentration and cell volume. These secondary active transporters exchange sodium ions against protons via an alternating access mechanism, which is not understood in full detail. Na+/H+ antiporters show distinct species-specific transport characteristics and regulatory properties that correlate with respective physiological functions. Here we present the characterization of the Na+/H+ antiporter NhaA from Salmonella enterica serovar Thyphimurium LT2, the causing agent of food-born human gastroenteritis and typhoid like infections. The recombinant antiporter was functional in vivo and in vitro. Expression of its gene complemented the Na+-sensitive phenotype of an E. coli strain that lacks the main Na+/H+ antiporters. Purified to homogeneity, the antiporter was a dimer in solution as accurately determined by size-exclusion chromatography combined with multi-angle laser-light scattering and refractive index monitoring. The purified antiporter was fully capable of electrogenic Na+(Li+)/H+-antiport when reconstituted in proteoliposomes and assayed by solid-supported membrane-based electrophysiological measurements. Transport activity was inhibited by 2-aminoperimidine. The recorded negative currents were in agreement with a 1Na+(Li+)/2H+ stoichiometry. Transport activity was low at pH 7 and up-regulation above this pH value was accompanied by a nearly 10-fold decrease of KmNa (16 mM at pH 8.5) supporting a competitive substrate binding mechanism. K+ does not affect Na+ affinity or transport of substrate cations, indicating that selectivity of the antiport arises from the substrate binding step. In contrast to homologous E. coli NhaA, transport activity remains high at pH values above 8.5. The antiporter from S. Typhimurium is a promising candidate for combined structural and

  4. Molecular Characterization of the Na+/H+-Antiporter NhaA from Salmonella Typhimurium

    PubMed Central

    Lentes, Christopher J.; Mir, Syed H.; Boehm, Marc; Ganea, Constanta; Fendler, Klaus; Hunte, Carola

    2014-01-01

    Na+/H+ antiporters are integral membrane proteins that are present in almost every cell and in every kingdom of life. They are essential for the regulation of intracellular pH-value, Na+-concentration and cell volume. These secondary active transporters exchange sodium ions against protons via an alternating access mechanism, which is not understood in full detail. Na+/H+ antiporters show distinct species-specific transport characteristics and regulatory properties that correlate with respective physiological functions. Here we present the characterization of the Na+/H+ antiporter NhaA from Salmonella enterica serovar Thyphimurium LT2, the causing agent of food-born human gastroenteritis and typhoid like infections. The recombinant antiporter was functional in vivo and in vitro. Expression of its gene complemented the Na+-sensitive phenotype of an E. coli strain that lacks the main Na+/H+ antiporters. Purified to homogeneity, the antiporter was a dimer in solution as accurately determined by size-exclusion chromatography combined with multi-angle laser-light scattering and refractive index monitoring. The purified antiporter was fully capable of electrogenic Na+(Li+)/H+-antiport when reconstituted in proteoliposomes and assayed by solid-supported membrane-based electrophysiological measurements. Transport activity was inhibited by 2-aminoperimidine. The recorded negative currents were in agreement with a 1Na+(Li+)/2H+ stoichiometry. Transport activity was low at pH 7 and up-regulation above this pH value was accompanied by a nearly 10-fold decrease of Km Na (16 mM at pH 8.5) supporting a competitive substrate binding mechanism. K+ does not affect Na+ affinity or transport of substrate cations, indicating that selectivity of the antiport arises from the substrate binding step. In contrast to homologous E. coli NhaA, transport activity remains high at pH values above 8.5. The antiporter from S. Typhimurium is a promising candidate for combined structural and

  5. NaK Variable Conductance Heat Pipe for Radioisotope Stirling Systems

    NASA Technical Reports Server (NTRS)

    Tarau, Calin; Anderson, William G.; Walker, Kara

    2008-01-01

    In a Stirling radioisotope power system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides most of this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending use of that convertor for the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling convertor. In the design of the VCHP for the Advanced Stirling Radioisotope Generator, the VCHP reservoir temperature can vary between 40 and 120 C. While sodium, potassium, or cesium could be used as the working fluid, their melting temperatures are above the minimum reservoir temperature, allowing working fluid to freeze in the reservoir. In contrast, the melting point of NaK is -12 C, so NaK can't freeze in the reservoir. One potential problem with NaK as a working fluid is that previous tests with NaK heat pipes have shown that NaK heat pipes can develop temperature non-uniformities in the evaporator due to NaK's binary composition. A NaK heat pipe was fabricated to measure the temperature non-uniformities in a scale model of the VCHP for the Stirling Radioisotope system. The temperature profiles in the evaporator and condenser were measured as a function of operating temperature and power. The largest delta T across the condenser was 2S C. However, the condenser delta T decreased to 16 C for the 775 C vapor temperature at the highest heat flux applied, 7.21 W/ square cm. This decrease with increasing heat flux was caused by the increased mixing of the sodium and potassium in the vapor. This temperature differential is similar to the temperature variation in this ASRG heat transfer interface without a heat pipe, so NaK can be used as the VCHP working fluid.

  6. INTEX-NA: Intercontinental Chemical Transport Experiment - North America

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.; Jacob, D.; Pfister, L.; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    INTEX-NA is an integrated atmospheric chemistry field experiment to be performed over North America using the NASA DC-8 and P-3B aircraft as its primary platforms. It seeks to understand the exchange of chemicals and aerosols between continents and the global troposphere. The constituents of interest are ozone and its precursors (hydrocarbons, NOX and HOX), aerosols, and the major greenhouse gases (CO2, CH4, N2O). INTEX-NA will provide the observational database needed to quantify inflow, outflow, and transformations of chemicals over North America. INTEX-NA is to be performed in two phases. Phase A will take place during the period of May-August 2004 and Phase B during March-June 2006. Phase A is in summer when photochemistry is most intense and climatic issues involving aerosols and carbon cycle are most pressing, and Phase B is in spring when Asian transport to North America is at its peak. INTEX-NA will coordinate its activities with concurrent measurement programs including satellites (e. g. Terra, Aura, Envisat), field activities undertaken by the North American Carbon Program (NACP), and other U.S. and international partners. However, it is being designed as a 'stand alone' mission such that its successful execution is not contingent on other programs. Synthesis of the ensemble of observation from surface, airborne, and space platforms, with the help of global/regional models is an important It is anticipated that approximately 175 flight hours for each of the aircraft (DC-8 and P-3B) will be required for each Phase. Principal operational sites are tentatively selected to be Bangor, ME; Wallops Island, VA; Seattle, WA; Rhinelander, WI; Lancaster, CA; and New Orleans, LA. These coastal and continental sites can support large missions and are suitable for INTEX-NA objectives. The experiment will be supported by forecasts from meteorological and chemical models, satellite observations, surface networks, and enhanced O3,-sonde releases. In addition to

  7. Effect of Alkali Metal Cations on Slow Inactivation of Cardiac Na+ Channels

    PubMed Central

    Townsend, Claire; Horn, Richard

    1997-01-01

    Human heart Na+ channels were expressed transiently in both mammalian cells and Xenopus oocytes, and Na+ currents measured using 150 mM intracellular Na+. The kinetics of decaying outward Na+ current in response to 1-s depolarizations in the F1485Q mutant depends on the predominant cation in the extracellular solution, suggesting an effect on slow inactivation. The decay rate is lower for the alkali metal cations Li+, Na+, K+, Rb+, and Cs+ than for the organic cations Tris, tetramethylammonium, N-methylglucamine, and choline. In whole cell recordings, raising [Na+]o from 10 to 150 mM increases the rate of recovery from slow inactivation at −140 mV, decreases the rate of slow inactivation at relatively depolarized voltages, and shifts steady-state slow inactivation in a depolarized direction. Single channel recordings of F1485Q show a decrease in the number of blank (i.e., null) records when [Na+]o is increased. Significant clustering of blank records when depolarizing at a frequency of 0.5 Hz suggests that periods of inactivity represent the sojourn of a channel in a slow-inactivated state. Examination of the single channel kinetics at +60 mV during 90-ms depolarizations shows that neither open time, closed time, nor first latency is significantly affected by [Na+]o. However raising [Na+]o decreases the duration of the last closed interval terminated by the end of the depolarization, leading to an increased number of openings at the depolarized voltage. Analysis of single channel data indicates that at a depolarized voltage a single rate constant for entry into a slow-inactivated state is reduced in high [Na+]o, suggesting that the binding of an alkali metal cation, perhaps in the ion-conducting pore, inhibits the closing of the slow inactivation gate. PMID:9234168

  8. ORTHO-PARA SELECTION RULES IN THE GAS-PHASE CHEMISTRY OF INTERSTELLAR AMMONIA

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Faure, A.; Hily-Blant, P.; Le Gal, R.

    The ortho-para chemistry of ammonia in the cold interstellar medium is investigated using a gas-phase chemical network. Branching ratios for the primary reaction chain involved in the formation and destruction of ortho- and para-NH{sub 3} were derived using angular momentum rules based on the conservation of the nuclear spin. We show that the 'anomalous' ortho-to-para ratio of ammonia ({approx}0.7) observed in various interstellar regions is in fact consistent with nuclear spin selection rules in a para-enriched H{sub 2} gas. This ratio is found to be independent of temperature in the range 5-30 K. We also predict an ortho-to-para ratio ofmore » {approx}2.3 for NH{sub 2}. We conclude that a low ortho-to-para ratio of H{sub 2} naturally drives the ortho-to-para ratios of nitrogen hydrides below the statistical values.« less

  9. Alteration of aluminium inhibition of synaptosomal (Na(+)/K(+))ATPase by colestipol administration.

    PubMed

    Silva, V S; Oliveira, L; Gonçalves, P P

    2013-11-01

    The ability of aluminium to inhibit the (Na(+)/K(+))ATPase activity has been observed by several authors. During chronic dietary exposure to AlCl3, brain (Na(+)/K(+))ATPase activity drops, even if no alterations of catalytic subunit protein expression and of energy charge potential are observed. The aluminium effect on (Na(+)/K(+))ATPase activity seems to implicate the reduction of interacting protomers within the oligomeric ensemble of the membrane-bound (Na(+)/K(+))ATPase. The activity of (Na(+)/K(+))ATPase is altered by the microviscosity of lipid environment. We studied if aluminium inhibitory effect on (Na(+)/K(+))ATPase is modified by alterations in synaptosomal membrane cholesterol content. Adult male Wistar rats were submitted to chronic dietary AlCl3 exposure (0.03 g/day of AlCl3) and/or to colestipol, a hypolidaemic drug (0.31 g/day) during 4 months. The activity of (Na(+)/K(+))ATPase was studied in brain cortex synaptosomes with different cholesterol contents. Additionally, we incubate synaptosomes with methyl-β-cyclodextrin for both enrichment and depletion of membrane cholesterol content, with or without 300 μM AlCl3. This enzyme activity was significantly reduced by micromolar AlCl3 added in vitro and when aluminium was orally administered to rats. The oral administration of colestipol reduced the cholesterol content and concomitantly inhibited the (Na(+)/K(+))ATPase. The aluminium inhibitory effect on synaptosomal (Na(+)/K(+))ATPase was reduced by cholesterol depletion both in vitro and in vivo. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. A new high-energy cathode for a Na-ion battery with ultrahigh stability.

    PubMed

    Park, Young-Uk; Seo, Dong-Hwa; Kwon, Hyung-Soon; Kim, Byoungkook; Kim, Jongsoon; Kim, Haegyeom; Kim, Inkyung; Yoo, Han-Ill; Kang, Kisuk

    2013-09-18

    Large-scale electric energy storage is a key enabler for the use of renewable energy. Recently, the room-temperature Na-ion battery has been rehighlighted as an alternative low-cost technology for this application. However, significant challenges such as energy density and long-term stability must be addressed. Herein, we introduce a novel cathode material, Na1.5VPO4.8F0.7, for Na-ion batteries. This new material provides an energy density of ~600 Wh kg(-1), the highest value among cathodes, originating from both the multielectron redox reaction (1.2 e(-) per formula unit) and the high potential (~3.8 V vs Na(+)/Na) of the tailored vanadium redox couple (V(3.8+)/V(5+)). Furthermore, an outstanding cycle life (~95% capacity retention for 100 cycles and ~84% for extended 500 cycles) could be achieved, which we attribute to the small volume change (2.9%) upon cycling, the smallest volume change among known Na intercalation cathodes. The open crystal framework with two-dimensional Na diffusional pathways leads to low activation barriers for Na diffusion, enabling excellent rate capability. We believe that this new material can bring the low-cost room-temperature Na-ion battery a step closer to a sustainable large-scale energy storage system.

  11. A possible mechanism for low affinity of silkworm Na+/K+-ATPase for K.

    PubMed

    Homareda, Haruo; Otsu, Masahiro; Yamamoto, Sachiko; Ushimaru, Makoto; Ito, Sayaka; Fukutomi, Toshiyuki; Jo, Taeho; Eishi, Yoshinobu; Hara, Yukichi

    2017-12-01

    The affinity for K + of silkworm nerve Na + /K + -ATPase is markedly lower than that of mammalian Na + /K + -ATPase (Homareda 2010). In order to obtain clues on the molecular basis of the difference in K + affinities, we cloned cDNAs of silkworm (Bombyx mori) nerve Na + /K + -ATPase α and β subunits, and analyzed the deduced amino acid sequences. The molecular masses of the α and β subunits were presumed to be 111.5 kDa with ten transmembrane segments and 37.7 kDa with a single transmembrane segment, respectively. The α subunit showed 75% identity and 93% homology with the pig Na + /K + -ATPase α1 subunit. On the other hand, the amino acid identity of the β subunit with mammalian counterparts was as low as 30%. Cloned α and β cDNAs were co-expressed in cultured silkworm ovary-derived cells, BM-N cells, which lack endogenous Na + /K + -ATPase. Na + /K + -ATPase expressed in the cultured cells showed a low affinity for K + and a high affinity for Na + , characteristic of the silkworm nerve Na + /K + -ATPase. These results suggest that the β subunit is responsible for the affinity for K + of Na + /K + -ATPase.

  12. First-principles study of amorphous carbon: a promising candidate for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Kotsis, Konstantinos; Legrain, Fleur; Manzhos, Sergei

    2015-03-01

    The perspective of a widespread use of clean but intermittent sources of electricity (wind and solar) as well as that of hybrid electric vehicles calls for alternatives to Li-ion batteries as Li resources are limited. Na being abundant, cheap, and a relatively light and small atom, Na-ion batteries have attracted a lot of interest the past few years. However, while most of the Na-ion batteries studies focus on the positive electrode, the negative electrode remains little investigated and an efficient anode providing all a good capacity, a high cycle life, and a descent rate of charge/discharge, is still not available. The efficient electrode materials for Li, in particular diamond Si and graphite C, have been shown to not allow the intercalation of Na [1, 2]. Computational studies report positive intercalation energies [3, 4] and therefore suggest that the insertion of Na into the crystalline framework (C and Si) is thermodynamically not favored: Na atoms prefer to gather into Na clusters rather than to intercalate into the crystalline phase. Amorphization of Si was found to be a valid strategy to improve the interaction between Si and Na [3]. We investigate here the effects of amorphization of C on its storage properties vis-à-vis Na (as well as Li for reference).

  13. IR-IR Conformation Specific Spectroscopy of Na+(Glucose) Adducts

    NASA Astrophysics Data System (ADS)

    Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

    2018-01-01

    We report an IR-IR double resonance study of the structural landscape present in the Na+(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na+(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctive Na+ coordination. [Figure not available: see fulltext.

  14. Evaluation of thermochemical biomass conversion in fluidized bed =

    NASA Astrophysics Data System (ADS)

    Neves, Daniel dos Santos Felix das

    elementares e poderes calorificos. O resultado traduziu-se num conjunto de parâmetros empiricos de interesse pratico que permitiram elucidar o comportamento geral da pirolise de biomassa numa gama ampla de condicoes operatorias. Para alem disso, propos-se um modelo empirico para a composicao dos volateis que pode ser integrado em modelos compreensivos de reatores desde que os parâmetros usados sejam adequados ao combustivel ensaiado. Esta abordagem despoletou um conjunto de ensaios de pirolise com varias biomassas, lenhina e celulose, e temperaturas entre os 600 e 975ºC. Elevadas taxas de aquecimento do combustivel foram alcancadas em reatores laboratoriais de leito fluidizado borbulhante e leito fixo, ao passo que um sistema termo-gravimetrico permitiu estudar o efeito de taxas de aquecimento mais baixas. Os resultados mostram que, em condicoes tipicas de processos de combustao e gasificacao, a quantidade de volateis libertada da biomassa e pouco influenciada pela temperatura do reator mas varia bastante entre combustiveis. Uma analise mais aprofundada deste assunto permitiu mostrar que o rendimento de carbonizado esta intimamente relacionado com o racio O/C do combustivel original, sendo proposto um modelo simples para descrever esta relacao. Embora a quantidade total de volateis libertada seja estabelecida pela composicao da biomassa, a respetiva composicao quimica depende bastante da temperatura do reator. Rendimentos de especies condensaveis (agua e especies orgânicas), CO2 e hidrocarbonetos leves descrevem um maximo relativamente a temperatura para dar lugar a CO e H2 as temperaturas mais altas. Nao obstante, em certas gamas de temperatura, os rendimentos de algumas das principais especies gasosas (e.g. CO, H2, CH4) estao bem correlacionados entre si, o que permitiu desenvolver modelos empiricos que minimizam o efeito das condicoes operatorias e, ao mesmo tempo, realcam o efeito do combustivel na composicao do gas. Em suma, os ensaios de pirolise realizados neste

  15. Development of Network Interface Cards for TRIDAQ systems with the NaNet framework

    NASA Astrophysics Data System (ADS)

    Ammendola, R.; Biagioni, A.; Cretaro, P.; Di Lorenzo, S.; Fiorini, M.; Frezza, O.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Valente, P.; Vicini, P.

    2017-03-01

    NaNet is a framework for the development of FPGA-based PCI Express (PCIe) Network Interface Cards (NICs) with real-time data transport architecture that can be effectively employed in TRIDAQ systems. Key features of the architecture are the flexibility in the configuration of the number and kind of the I/O channels, the hardware offloading of the network protocol stack, the stream processing capability, and the zero-copy CPU and GPU Remote Direct Memory Access (RDMA). Three NIC designs have been developed with the NaNet framework: NaNet-1 and NaNet-10 for the CERN NA62 low level trigger and NaNet3 for the KM3NeT-IT underwater neutrino telescope DAQ system. We will focus our description on the NaNet-10 design, as it is the most complete of the three in terms of capabilities and integrated IPs of the framework.

  16. 23Na and 39K NMR studies of ion transport in human erythrocytes.

    PubMed

    Ogino, T; Shulman, G I; Avison, M J; Gullans, S R; den Hollander, J A; Shulman, R G

    1985-02-01

    Ion transport in human erythrocytes was studied by 23Na and 39K NMR with an anionic paramagnetic shift reagent, Dy(P3O10)2(7-). The intra- and extracellular 23Na and 39K NMR signals were well separated (over 10 ppm) at 5 mM concentration of the shift reagent. The NMR visibility of the intracellular Na+ and K+ was determined to be 100% in human and duck erythrocytes. The intracellular ion concentrations were 8.1 +/- 0.8 mM Na+ (n = 7) and 110 +/- 12 mM K+ (n = 4) for fresh human erythrocytes. The ouabain-sensitive net Na+ efflux was 1.75 +/- 0.08 mmol/hr per liter of cells at 37 degrees C (n = 3). The gramicidin-induced ion transport in human erythrocytes was also studied by 23Na and 39K NMR or by simultaneous measurements of 23Na NMR and a K+-selective electrode. The time courses of the Na+ and K+ transport induced by the ionophore were biphasic. The initial rapid fluxes were due to an exchange of Na+ for K+, which were found to occur with a 1:1 stoichiometry. The subsequent slow components were the net Na+ and K+ effluxes rate-limited by the Cl- permeability and accompanied by a reduction in cell volume. The Cl- permeability determined from the NMR measurements of these slow fluxes was 3.2 +/- 0.5 X 10(-8) cm/sec at 25 degrees C (n = 4).

  17. 23Na and 39K NMR studies of ion transport in human erythrocytes.

    PubMed Central

    Ogino, T; Shulman, G I; Avison, M J; Gullans, S R; den Hollander, J A; Shulman, R G

    1985-01-01

    Ion transport in human erythrocytes was studied by 23Na and 39K NMR with an anionic paramagnetic shift reagent, Dy(P3O10)2(7-). The intra- and extracellular 23Na and 39K NMR signals were well separated (over 10 ppm) at 5 mM concentration of the shift reagent. The NMR visibility of the intracellular Na+ and K+ was determined to be 100% in human and duck erythrocytes. The intracellular ion concentrations were 8.1 +/- 0.8 mM Na+ (n = 7) and 110 +/- 12 mM K+ (n = 4) for fresh human erythrocytes. The ouabain-sensitive net Na+ efflux was 1.75 +/- 0.08 mmol/hr per liter of cells at 37 degrees C (n = 3). The gramicidin-induced ion transport in human erythrocytes was also studied by 23Na and 39K NMR or by simultaneous measurements of 23Na NMR and a K+-selective electrode. The time courses of the Na+ and K+ transport induced by the ionophore were biphasic. The initial rapid fluxes were due to an exchange of Na+ for K+, which were found to occur with a 1:1 stoichiometry. The subsequent slow components were the net Na+ and K+ effluxes rate-limited by the Cl- permeability and accompanied by a reduction in cell volume. The Cl- permeability determined from the NMR measurements of these slow fluxes was 3.2 +/- 0.5 X 10(-8) cm/sec at 25 degrees C (n = 4). PMID:2579385

  18. Identification of a 3rd Na+ Binding Site of the Glycine Transporter, GlyT2.

    PubMed

    Subramanian, Nandhitha; Scopelitti, Amanda J; Carland, Jane E; Ryan, Renae M; O'Mara, Megan L; Vandenberg, Robert J

    2016-01-01

    The Na+/Cl- dependent glycine transporters GlyT1 and GlyT2 regulate synaptic glycine concentrations. Glycine transport by GlyT2 is coupled to the co-transport of three Na+ ions, whereas transport by GlyT1 is coupled to the co-transport of only two Na+ ions. These differences in ion-flux coupling determine their respective concentrating capacities and have a direct bearing on their functional roles in synaptic transmission. The crystal structures of the closely related bacterial Na+-dependent leucine transporter, LeuTAa, and the Drosophila dopamine transporter, dDAT, have allowed prediction of two Na+ binding sites in GlyT2, but the physical location of the third Na+ site in GlyT2 is unknown. A bacterial betaine transporter, BetP, has also been crystallized and shows structural similarity to LeuTAa. Although betaine transport by BetP is coupled to the co-transport of two Na+ ions, the first Na+ site is not conserved between BetP and LeuTAa, the so called Na1' site. We hypothesized that the third Na+ binding site (Na3 site) of GlyT2 corresponds to the BetP Na1' binding site. To identify the Na3 binding site of GlyT2, we performed molecular dynamics (MD) simulations. Surprisingly, a Na+ placed at the location consistent with the Na1' site of BetP spontaneously dissociated from its initial location and bound instead to a novel Na3 site. Using a combination of MD simulations of a comparative model of GlyT2 together with an analysis of the functional properties of wild type and mutant GlyTs we have identified an electrostatically favorable novel third Na+ binding site in GlyT2 formed by Trp263 and Met276 in TM3, Ala481 in TM6 and Glu648 in TM10.

  19. Structure and properties of α-NaFeO{sub 2}-type ternary sodium iridates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baroudi, Kristen, E-mail: kbaroudi@princeton.edu; Yim, Cindi; Wu, Hui

    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 α-NaFeO{submore » 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

  20. Crystallization of the Na+-translocating NADH:quinone oxidoreductase from Vibrio cholerae

    PubMed Central

    Casutt, Marco S.; Wendelspiess, Severin; Steuber, Julia; Fritz, Günter

    2010-01-01

    The Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) from the human pathogen Vibrio cholerae couples the exergonic oxidation of NADH by membrane-bound quinone to Na+ translocation across the membrane. Na+-NQR consists of six different subunits (NqrA–NqrF) and contains a [2Fe–2S] cluster, a noncovalently bound FAD, a noncovalently bound riboflavin, two covalently bound FMNs and potentially Q8 as cofactors. Initial crystallization of the entire Na+-NQR complex was achieved by the sitting-drop method using a nanolitre dispenser. Optimization of the crystallization conditions yielded flat yellow-coloured crystals with dimensions of up to 200 × 80 × 20 µm. The crystals diffracted to 4.0 Å resolution and belonged to space group P21, with unit-cell parameters a = 94, b = 146, c = 105 Å, α = γ = 90, β = 111°. PMID:21139223