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1

Anlise Comparativa entre rvores de Deciso e TRISS na Predio de Sobrevida de Pacientes Traumatizados  

E-print Network

, Afonso Dinis Costa Passos2 , Domingos Alves2 , José Augusto Baranauskas1 1 Departamento de Física eAnálise Comparativa entre Árvores de Decisão e TRISS na Predição de Sobrevida de Pacientes Matemática Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto Universidade de São Paulo (USP

Baranauskas, José Augusto

2

FASCODE for the environment (FASE)  

NASA Astrophysics Data System (ADS)

The Optical Physics Division of the Phillips Laboratory with support from the DoE Atmospheric Radiation Measurement (ARM) Program is developing a state-of-the-art line-by- line atmospheric radiative transfer model as the successor by FASCODE. The goal of this project is to create a computationally efficient model which contains the most up-to-date physics. The new model, known as FASCODE for the Environment, or `FASE', will combine the best features of FASCODE and LBLRTM, the DoE's standard radiative transfer model. FASE will also contain new features such as new cross-sections for heavy molecules, an improved solar irradiance model, and improvements to the Schumann-Runge bands and continuum. The code will be optimized for vectorized and/or parallel processing, put under configuration control for easy maintenance, and will be structured into separate modules for each function: atmospheric profiles, layer optical properties, radiative transfer, multiple- scattering, etc. This modular structure will allow for increased flexibility and easy customization of the code for specialized applications, such as a forward model for iterative inversion algorithms. Ease-of-use will be enhanced with improved input control structures and documentation to accommodate the needs of novice and advanced users. This paper addresses changes which have been made to FASCODE and LBLRTM to create FASE, and gives an overview of the modular structure and its capabilities.

Snell, Hilary E.; Moncet, Jean-Luc; Anderson, Gail P.; Chetwynd, James H., Jr.; Miller, S.; Wang, Junfeng

1995-06-01

3

LINK2009 FASE 1 UDVIKLING AF 2. GEN. BRNDSELSCELLE  

E-print Network

LINK2009 FASE 1 »UDVIKLING AF 2. GEN. BR?NDSELSCELLE K?RET?JER OG BRINTTANKSTATION« SLUTRAPPORT: Brændselscelle bil fra LINK2009 til almindeligt bilsyn i Herning #12;LINK2009 FASE 1 SLUTRAPPORT MARTS 2010 Foreningen Hydrogen Link Danmark | www.hydrogenlink.net Side 2 af 56 Indledning & sammendrag I begyndelsen af

4

DISEOS ADAPTATIVOS PARA ENSAYOS CLNICOS FASE II O III EN PACIENTES CON CANCER EN CUBA  

Microsoft Academic Search

The Center of Molecular Immunology (CIM) has developed since its creation, different molecules for the treatment of cancer. The development of these products, has allowed an advance in clinical trials phases. This brings consequently an increment of the number of studies and also in the number of hospitals recruiting patients. In this moment, we are working with 15 different products,

M. M. Fors; M. Robaina Garca; P. Lorenzo-Luaces; T. Crombet Ramos; A. Macas Abraham; B. Wilkinson Brito; Martnez Prez; M. Troche Concepcin; A. Lage

5

ptica adaptativa con un modulador fase programable de cristal lquido ptica adaptativa con un modulador fase programable de cristal lquido  

Microsoft Academic Search

El modulador de fase programable es un modulador espacial de cristal lquido controlado pticamente que constituye una buena alternativa a los espejos deformables para la modificacin del frente de onda ocular. En el presente trabajo se demuestra la viabilidad de este instrumento en experimentos de ptica adaptativa en el campo de la ptica visual. En primer lugar se describen los

P. M. Prieto; E. J. Fernndez; S. Manzanera; D. B. Ayala; P. Artal

6

Seminrio de Socializao: Estgio na  

E-print Network

Socialização da disciplina de Estágio Supervisionado na Educação Infantil, Curso de Pedagogia/UFSC (2013Seminário de Socialização: Estágio na Educação Infantil 09 de Dezembro 14h - Abertura do Seminário Infantil, Anos Iniciais e estudantes das 6ª e 7ª fases. 15h30m - Encerramento do Seminário. Mesa "Relações

Floeter, Sergio Ricardo

7

A Proposed Activity for a Meaningful Learning about the Moon Phases. (Breton Title: Uma Proposta de Atividade Para a Aprendizagem Significativa sobre as Fases da Lua.) Una Actividad Propuesta Para EL Aprendizaje Significativo Acerca de Las Fases de la Luna  

NASA Astrophysics Data System (ADS)

This paper presents one of the concepts of Astronomy and its consequent failure in teaching this topic in high school, even when the official documents point out the necessity of Astronomy teaching at this school level. Among the spontaneous conceptions in Astronomy that high school students carry with them, even after the end of the school, we emphasized in this research the Moon phases. The development of different strategies in relation to traditional methods, aimed to teaching-learning process on this topic was considered in this study. These strategies were devised based on the reference frame of the Meaningful Learning, as elaborated by Ausubel. The proposals presented here include the active participation of students in experimental activities and other didactic activities, for their continuous evaluation during the process. These activities finished with a Comics elaboration about the Moon phases. Therefore, the objective of this paper is to present a proposal for differentiated teaching activity about Moon phases supported by the theoretical principles of Meaningful Learning at Physics classes. Este texto foca um dos contedos de Astronomia e a consequente falha no ensino deste tema no ensino mdio, apesar de os documentos oficiais apresentarem a necessidade de se trabalhar a Astronomia neste nvel de ensino. Dentre as concepes alternativas em Astronomia que os alunos do ensino mdio carregam consigo, mesmo aps o trmino dos estudos, destacamos, nesta pesquisa, o fenmeno das fases da Lua. O desenvolvimento de estratgias diferenciadas em relao ao ensino tradicional, visando o processo de ensino-aprendizagem sobre este tema, foi contemplado neste trabalho como um dos resultados obtidos sob a luz dos referenciais da aprendizagem significativa, fundamentados em Ausubel. Segundo a proposta aqui apresentada, a participao ativa dos alunos na execuo de uma atividade experimental e outras atividades didticas, que visam sua contnua avaliao durante o processo, culmina com a elaborao de uma histria em quadrinhos envolvendo as fases da Lua. Portanto, o objetivo deste trabalho apresentar uma proposta de atividade didtica diferenciada sustentada pelos princpios tericos da aprendizagem significativa aplicada ao ensino das fases da Lua durante as aulas de Fsica no ensino mdio. En este trabajo se presenta uno de los contenidos de la Astronoma y el evidente fracaso en la enseanza del tema en la escuela secundaria, a pesar del hecho que los documentos oficiales apuntan para la necesidad de trabajar contenidos de Astronoma en este nivel. Entre los conceptos alternativos en Astronoma que los alumnos secundarios llevan consigo, an despus de terminados los estudios, destacamos aqu el fenmeno de las fases de la Luna. El desarrollo de diferentes estrategias en relacin con los mtodos tradicionales, dirigidas al proceso de enseanza-aprendizaje en este tema fue considerado en este trabajo como uno de los resultados obtenidos a la luz de los referenciales del aprendizaje significativo, tal como fueron fundamentados por Ausubel. Segn la propuesta que aqu se presenta, la participacin activa de los estudiantes en la ejecucin de una actividad experimental y otras actividades educativas destinadas a la evaluacin continua durante el proceso culmin en la elaboracin de una historieta respecto de las fases de la Luna. Por lo tanto, el objetivo de este trabajo es presentar una propuesta de actividad de enseanza diferenciada con el apoyo de los principios tericos del aprendizaje significativo aplicado a la enseanza de las fases de la luna durante las clases de fsica del ciclo secundario.

Martins, Bruno Andrade; Langhi, Rodolfo

2012-12-01

8

Aplicacin de tcnicas de usabilidad con inclusin en la Fase de Anlisis de Requisitos  

Microsoft Academic Search

En este artculo se presenta un caso prctico de utilizacin de tcnicas de usabilidad con inclusin en la Fase de Anlisis de requisitos en el ciclo de desarrollo Web siguiendo una metodologa de Diseo Centrado en el Usuario. Como caso prctico, se va a mostrar la aplicacin de tcnicas cmo Perfiles de Usuario, Persona, Escenarios y Card Sorting como soporte

Lourdes Moreno; Paloma Martinez; Belen Ruiz

9

Demonstrating the Practical Advantages of the Scalable and Interoperable Astronomical Framework FASE: Applications to EUCLID Simulations and LUCIFER Data Reduction  

NASA Astrophysics Data System (ADS)

The European OPTICON Networks 3.6 and 9.2 in collaboration with the Virtual Observatory, during the last years have produced a detailed document, designing the requirements and the architecture of a future scalable and interoperable desktop framework for the astronomical software (FASE). A first reference implementation of the FASE framework has been developed at INAF-IASF Milano and applied to different projects we are involved in: a) the simulation software developed to study the performance of the EUCLID NISP instrument; b) the LBT LUCIFER instrument reduction pipeline used by the Italian community. An application involving graphical capabilities is also being developed exploiting FASE facilities. We show how the main architectural concepts of the FASE framework have been successfully applied to the software mentioned above, providing easy to use and install interoperable software, equipped with distributed and scalable capabilities. See also Grosbl et al. (2012).

Paioro, L.; Garilli, B.; Franzetti, P.; Fumana, M.; Scodeggio, M.; Grosbl, P.; Tody, D.; Surace, C.

2012-09-01

10

Validation of FASE (FASCODE for the Environment) and MODTRAN3: updates and comparisons with clear-sky measurements  

NASA Astrophysics Data System (ADS)

FASE is a line-by-line (LBL) atmospheric radiation code, grounded in the original USAF FASCODE (Fast Atmospheric Signature Code) line shape decomposition algorithm. The Department of Energy Atmospheric Radiation Measurement (ARM) Program and the AF/PL Geophysics Directorate jointly supported FASE which now envelops both agencies' important upgrades. ARM's LBLRTM (LBL Radiative Transfer Model authored by S.A. Clough and P.D. Brown of AER, Inc.) expanded the FASCODE algorithms to specifically address scientific and coding issues of particular concern to the climate community including: H20 and C02 continua, lineshape, radiance algorithms, sampling, vectorization, array parameterization, spectral ranges and inputloutput modes. These features have then been recombined with FASCODE non- LTE and laser options, plus shared common elements from MODTRAN (Moderate Resolution Transmittance Model, a 2 cm- band model) evolution. These include a new solar irradiance and UV cross sections. Examples of the feedback and validation between FASE and MODTRAN3 will be presented.

Snell, Hilary E.; Anderson, Gail P.; Wang, Jinxue; Moncet, Jean-Luc; Chetwynd, James H., Jr.; English, Stephen J.

1995-12-01

11

Valoracin del paciente que solicita muerte asistida  

Microsoft Academic Search

ResumenEl equipo mdico debe estar preparado para evaluar a los pacientes que solicitan muerte asistida.\\u000a \\u000a En esta revisin hemos recopilado de la literatura internacional los criterios mdicos y psicolgicos para evaluar a los pacientes\\u000a que solicitan muerte asistida con la finalidad de aliviar las necesidades fisicas, psicolgicas y sociales de los pacientes\\u000a y sus familias.\\u000a \\u000a \\u000a \\u000a Se realiz un estudio de

R. Alczar-Oln; D. Reyes-Chiquete; R. Plancarte-Snchez

2003-01-01

12

RELACIN MDICO PACIENTE: DERECHOS DEL ADULTO MAYOR  

PubMed Central

Existen prejuicios en relacin con la vejez, incluso entre los profesionales que se dedican a la gerontologa. Uno comn y peligroso es considerar que los viejos son todos enfermos o discapacitados. La relacin mdico-paciente es la piedra angular de la prctica y tica mdicas. Para alcanzar el respeto por los adultos mayores es necesaria una medicina prudente, basada en una prctica en la cual la reflexin tica y clnica pueda contribuir. Esto ltimo es posible si se hacen valer los derechos del adulto mayor, en particular como paciente para la toma de decisiones. PMID:20379380

Barrantes-Monge, Melba; Rodrguez, Eduardo; Lama, Alexis

2009-01-01

13

Anlise de padres e processos de ocupao para a construo de modelos na Amaznia: Experimentos em Rondnia  

E-print Network

Análise de padrões e processos de ocupação para a construção de modelos na Amazônia: Experimentos Caixa Postal 515 - 12201-970 - São José dos Campos - SP, Brasil {isabel, anapaula, miguel, gilberto a região. Os procedimentos envolveram uma fase de diagnóstico com laboratório, campo e integração de dados

Camara, Gilberto

14

Seguridad del paciente en los estudios clnicos  

Cancer.gov

Informacin para pacientes, sus familiares y amigos, y el pblico en general, sobre cmo se protegen los derechos y la seguridad de las personas que participan en estudios clnicos. Conozca sobre el consentimiento formal, los consejos institucionales de revisin (IRB) y cmo se realiza la vigilancia continua de los estudios.

15

Zoneamento de riscos climticos para a cultura de milho na Regio Centro-Oeste do Brasil e para o estado de Minas Gerais Climatic risks zoning for maize production in West-Center Region and in Minas Gerais state, Brazil  

Microsoft Academic Search

Resumo - Para a cultura de milho, a gua um fator limitante, principalmente, na fase de germinao e nos perodos de florao e enchimento de gros. Desta forma, conhecer os elementos climticos uma estratgia para definir manejos que possibilitem minimizar riscos climticos, contribuindo para melhorar a poltica de alocao de recursos para crdito agrcola e para o aumento

Luiz Marcelo Aguiar Sans; Eduardo Delgado Assad; Daniel Pereira Guimares; Gisela Avellar

2001-01-01

16

VALOR DAS PROVAS DE POSICIONAMENTO DA PONTA DA AGULHA DE VERESS EM PUNO DO HIPOCNDRIO ESQUERDO NA INSTALAO DO PNEUMOPERITNIO THE VALUE OF TESTS RESULTS FOR VERESS NEEDLE TIP PLACEMENT INTRAPERITONEALLY IN THE LEFT HYPOCHONDRIUM FOR CREATING A PNEUMOPERITONEUM  

Microsoft Academic Search

RESUMO: Objetivo: Avaliar provas de posicionamento da agulha de Veress no hipocndrio esquerdo na criao do pneumoperitnio. Mtodo: Em cem pacientes puncionados no hipocndrio esquerdo, provas de posicionamento da agulha foram avaliadas, conside- rando-as positivas quando, na prova da aspirao ( PA), material orgnico era aspirado; na prova da resistncia ( PRes), exercia-se pequena fora no mbolo da seringa

Otvio Cansano de Azevedo; Joo Luiz Moreira; Coutinho Azevedo; Albino Augusto Sorbello; Gustavo Peixoto; Soares Miguel; Rodrigo Santa Cruz Guindalini; Antnio Cludio de Godoy

17

NaF Documentation  

Cancer.gov

The NaF documentation files are presented in Adobe Acrobat or Word files. PDF Generic Documentation for NaF PDF file Word Generic Documentation for NaFWord file Contact Paula M. Jacobs, Ph.D., 301-435-9181, jacobsp@mail.nih.gov, for information. Print

18

Familiares a cargo de pacientes de cncer (PDQ)  

Cancer.gov

Sumario informativo revisado por expertos acerca de los desafos que enfrentan los familiares a cargo de los pacientes con cncer. Este resumen se centra en las funciones tpicas y las inquietudes de las personas a cargo del paciente y en las intervenciones tiles para esas personas.

19

Report from NA49  

E-print Network

The signatures of the onset of deconfinement, found by the NA49 experiment at low SPS energies, are confronted with new results from the Beam Energy Scan (BES) program at BNL RHIC and CERN LHC results. Additionally, new NA49 results on chemical (particle ratio) fluctuations, azimuthal angle fluctuations, intermittency of di-pions, etc. are presented.

Katarzyna Grebieszkow; for the NA49 Collaboration

2011-12-04

20

K measurements with NA48/NA62  

NASA Astrophysics Data System (ADS)

The NA48/2 collaboration has analysed more than one million K??+?-e? decays, resulting in the improved determination of branching fraction by a factor of 3 and high precision form factor measurements. Concurrently, about 45000 K??0?0e? decays have been analyzed. Background contamination below the percent level and very good ?0 reconstruction allow the first accurate measurement of the branching fraction and decay form factor at the percent level. The achieved precision makes possible the observation of small effects such as ?+?-??0?0 re-scattering. Both K modes decay properties bring new precise inputs to Low Energy QCD studies and can provide strong tests of ChPT predictions. Future prospects include the observation of several thousand decays in similar muonic modes K??0?0?? and K??+?-??, that could be studied also in the forthcoming NA62 experiment.

Madigozhin, D.

2013-01-01

21

On efeito do achatamento nos pontos de equilbrio e na dinmica de sistemas coorbitais  

NASA Astrophysics Data System (ADS)

Neste trabalho analisamos o efeito do achatamento do corpo principal nos pontos de equilbrio lagrangianos e na configurao de rbitas girino-ferradura. Enfatizamos os sistemas coorbitais de satlites de Saturno, pois se encontram em relativa proximidade com o planeta, em que o efeito do achatamento se torna mais evidente. O estudo dividido em trs etapas independentes. Na primeira fase analisamos as equaes de movimento do problema restrito de trs corpos considerando o efeito do achatamento, e atravs do balanceamento de foras buscamos a nova configurao dos pontos de equilbrio lagrangianos. Conclumos, nesta etapa, que os pontos de equilbrio estveis apresentam um pequeno deslocamento definido pelo parmetro de achatamento, no podendo ser mais representados por tringulos eqilteros. Aplicamos este resultado aos satlites coorbitais de Tetis e Dione, encontrando as posies de equilbrio levemente deslocadas em relao ao caso sem achatamento. Na segunda fase visamos o sistema Saturno-Jano-Epimeteu, que por se tratar de um sistema de massas comparveis, optamos por desenvolver as equaes de Yoder et al (Icarus 53, pg 431-443, 1983), que permitem determinar os pontos de equilbrio e a amplitude de oscilao angular das rbitas girino-ferradura para o problema no-restrito de trs corpos, porm, no nosso estudo consideramos o efeito do achatamento do corpo principal nestas equaes. Encontramos que a distncia angular entre satlites, quando em posio de equilbrio estvel, diminui quanto maior for o parmetro de achatamento do corpo principal. Alm disso, a rbita de transio girino-ferradura possui largura angular menor em relao ao caso sem achatamento. Por fim, realizamos integraes numricas para os casos reais de coorbitais de Saturno comparando com os resultados analticos. Nestas integraes simulamos diversas rbitas girino-ferradura com diferentes parmetros de achatamento, utilizando condies iniciais corrigidas para a presena do achatamento.

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

2003-08-01

22

Photoabsorption resonances of Na20, Na21Cl and Na22Cl2 clusters  

NASA Astrophysics Data System (ADS)

Plasma resonance profiles in the visible part of the spectrum were measured by photoabsorption spectroscopy for the clusters Na20, Na21Cl and Na22Cl2 in a beam. The resonance positions in Na20 and Na21Cl are close, suggesting that the Cl- ion does not locate at the center of the metallic droplet and does not strongly modify the effective valence electron density. The spectrum of Na22Cl2 is noticeably dissimilar to the other two, raising the possibility of structural differences and/or incomplete charge transfer.

Xia, C.; Yin, C.; Kresin, V. V.

2009-04-01

23

Eventos arrtmicos en el paciente portador de un desfibrilador automtico implantable  

Microsoft Academic Search

INTRODUCCIN. El Desfibrilador Automtico Implantable (DAI) est ideado para prevenir la muerte sbita en pacientes de riesgo: es una estrategia teraputica de utilidad plenamente establecida como prevencin secundaria en pacientes que han padecido arritmias ventriculares malignas y con un nmero creciente de indicaciones para prevencin primaria en pacientes en riesgo de desarrollarlas.

Moreno Ambroj; Salazar Gonzlez; Jos Javier; Galache Osuna; Jos Gabriel; Snchez-Rubio Lezcano; Blanco Gonzlez; Snchez Insa; Guilln Marzo; Aragus Biescas

2007-01-01

24

BREAKFAST MENU (665 MG NA)  

E-print Network

), Cranberry(7.5 MG), Orange (5 MG), Prune(10 MG), V-8(85 MG) LOW SODIUM (2000 GM NA) ACCOMPANIMENTS: Fresh/Lowfat Italian/Lowfat French) (5 MG) DESSERTS: Angel Food Cake (280 MG) Diet Gelatin (5 MG) Diet Pudding: Vanilla SODIUM (2000 GM NA) COLD ENTREES: Chicken Caesar Salad (440 MG) (Oil & Vinegar/Lowfat Italian

Oliver, Douglas L.

25

PAX/hr. PAX/mi. $/Pass. Green Route (Old) n/a n/a n/a  

E-print Network

.0 (out of 6) n/a n/a Safety Committee Road Tests 4 5 11 4 15 Passing 4 4 9 3 14 Clinics Conducted 2 2 7 4 1 Charter MPH n/a n/a 10.35 14.76 13.28 Charter Cost/Hour n/a n/a $22.25 $24.80 $25.48 Customer

Acton, Scott

26

Pesquisas Baseadas na Localizao e na Orientao em Dispositivos Mveis  

E-print Network

Pesquisas Baseadas na Localização e na Orientação em Dispositivos Móveis Hugo Aguiar, Maria Beatriz Carmo, Paulo Pombinho, Ana Paula Afonso Departamento de Informática, Faculdade de Ciências, Universidade.di.fc.ul.pt,apa@di.fc.ul.pt Sumário A crescente utilização de dispositivos móveis e a sua evolução, com o surgimento de modelos

Carmo, Maria Beatriz

27

Challenges for Na-ion Negative Electrodes  

E-print Network

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

Chevrier, V. L.

28

Bioinformtica: Perspectivas na Medicina Bioinformtica: Perspectivas na Medicina Bioinformtica: Perspectivas na Medicina Bioinformtica: Perspectivas na Medicina Bioinformtica: Perspectivas na Medicina Bioinformatics: Perspectives in Medicine  

Microsoft Academic Search

A medicina moderna requer a integrao e anlise de grandes quantidades de dados genmicos, moleculares, celulares, associados a informaes clnicas, desta forma apresentando desafios fenomenais para a Bioinformtica. Esta rea interdisciplinar da cincia, que comeou com a anlise de seqncias gnicas e cresceu na direo do desenvolvimento de tcnicas automatizadas de anotao de genomas e transcriptomas, est agora caminhando na

Glaucius Oliva

2008-01-01

29

Familiares a cargo de pacientes de cncer: funciones y desafos (PDQ)  

Cancer.gov

Sumario informativo revisado por expertos acerca de los desafos que enfrentan los familiares a cargo de los pacientes con cncer. Este resumen se centra en las funciones tpicas y las inquietudes de las personas a cargo del paciente y en las intervenciones tiles para esas personas.

30

Impacto de las redes sociales de pacientes en la prctica asistencial  

Microsoft Academic Search

Las redes sociales de pacientes son espacios virtuales donde pacientes con condiciones similares se ponen en contacto y comparten tratamientos y problemas de salud. Estas redes ofrecen a las personas con problemas especficos de salud la oportunidad de compartir experiencias, buscar, recibir y proveer informacin, consejos e incluso apoyo emocional online. Pero, cul es el impacto de estas redes en

Elena Torrente; Joan Escarrabill; Tino Mart

2010-01-01

31

Tratamiento Quirrgico de los Meningiomas del Foramen ptico, Tcnicay Resultados de una Serie de 18 Pacientes  

PubMed Central

Introduccin: los meningiomas del foramen ptico producen un rpido deterioro de la funcin visual an cuando su tamao es pequeo, por eso su diagnstico y manejo difiere del resto de los meningiomas clinoideos. El propsito de este estudio es presentar la tcnica y los resultados de nuestro manejo quirrgico de meningiomas foraminales (MF). Pacientes y Mtodos: se llev a cabo una revisin de las historias clnicas de 47 pacientes con meningiomas primarios intraorbitarios. Se realizaron 52 cirugas en los pacientes con MF. Se emple una craneotoma fronto-orbitaria, seguida de una descompresin extradural del canal ptico, reseccin del componente intraorbitario y exploracin intradural del nervio ptico. Resultados: de los 12 pacientes con MF que presentaban la visin conservada, la agudeza visual fue preservada en 7 casos, mejor en 2, y empeor en 3. En 18 pacientes, el principal sntoma fue exoftalmos y en 35 pacientes ceguera unilateral. Ocurrieron 6 recurrencias, 2 a 10 aos despus de la reseccin quirrgica. Cinco de ellos fueron reoperados. Se indic radioterapia despus de la recurrencia en 3 pacientes. Conclusin: el manejo de los MF contina siendo controvertido y frecuentemente se propone un tratamiento conservador. Basados en nuestros hallazgos de frecuente extensin intracraneal, proponemos realizar una reseccin total o subtotal del tumor, preservando el nervio ptico en pacientes con visin prequirrgica conservada. PMID:25165616

Goldschmidt, Ezequiel; Ajler, Pablo; Campero, lvaro; Landriel, Federico; Sposito, Maximiliano; Carrizo, Antonio

2014-01-01

32

Formation Enthalpies of NaK Alloys.  

NASA Astrophysics Data System (ADS)

We have made accurate pseudopotential calculations of the total energy of Na, K, NaK in the CsCl structure, and Na_2K in the MgZn2 structure. For Na_2K, the only ordered alloy known to exist, we obtained a formation enthalpy H=-18 meV/atom whereas for NaK we obtained H=+7.5 meV/atom. It is argued that the negative H of Na_2K is a consequence of triangular bonds between some of the Na atoms.

Kleinman, Leonard; Zhu, Ming J.; Bylander, D. M.

1996-03-01

33

The Na-K-Cl Cotransporters  

Microsoft Academic Search

The Na-K-Cl cotransporters are a class of membrane proteins that transport Na, K, and Cl ions into and out of a wide variety of epithelial and nonepithelial cells. The transport process mediated by Na-K-Cl cotransporters is characterized by electroneutrality (almost always with stoichiometry of 1Na:1K:2Cl) and inhibition by the loop diuretics bumetanide, benzmetanide, and furosemide. Presently, two distinct Na-K-Cl cotransporter

Mark Haas; Bliss Forbush

1998-01-01

34

Original Contribution Involvement of Na+  

E-print Network

Original Contribution Involvement of Na+ /K+ -ATPase in hydrogen peroxide-induced hypertrophy production of reactive oxygen species (ROS) was required for ouabain-induced hypertrophy in cultured cardiac alone is sufficient to induce hypertrophy. A moderate amount of H2O2 was continuously generated

Brand, Paul H.

35

Europlanet NA2 Science Networking  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

36

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

SciTech Connect

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

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

1987-01-01

37

NA49 and NA61/SHINE experiments: results and perspectives  

E-print Network

The Super Proton Synchrotron (SPS) covers one of the most interesting regions of the QCD phase diagram $(T - \\mu_B)$. On the one hand there are indications that the energy threshold for deconfinement is reached already at low SPS energies. On the other hand theoretical calculations locate the QCD critical end-point at energies accessible at the SPS. In this paper the NA49 signatures of the onset of deconfinement are presented. Results are shown on pion production, the kaon to pion ratio, slopes of transverse mass spectra ("temperature"), and event-by-event particle ratio fluctuations versus collision energy, for central $Pb+Pb$ interactions. Next we show possible indications of the critical point in event-by-event mean transverse momentum and multiplicity fluctuations. Finally we discuss the future ion program of the NA61/SHINE experiment (energy scan with light ions).

Katarzyna Grebieszkow

2010-05-04

38

Dirio Econmico -Universidades A Repblica na Academia  

E-print Network

Dirio Econmico - Universidades A Repblica na Academia Autor: Carla Castro Id: 1067471 Data #12;Dirio Econmico - Universidades A Repblica na Academia Autor: Carla Castro Id: 1067465 Data.503,19 EUR #12;Dirio Econmico - Universidades A Repblica na Academia Autor: Carla Castro Id: 1067468 Data

Instituto de Sistemas e Robotica

39

Gleevec disminuye la recidiva del cncer en pacientes con tumor estromal gastrointestinal primario  

Cancer.gov

Los resultados preliminares de un estudio clnico grande aleatorio y controlado con placebo, en pacientes con tumor estromal gastrointestinal (GIST) primario, un tipo de tumor que por lo general se encuentra en el estmago o en el intestino delgado, demostraron que los pacientes a los que se administr mesilato de imatinib (Gleevec) luego de la extirpacin total de su tumor tuvieron una probabilidad significativamente menor de padecer una recidiva del cncer en comparacin con aquellos a los que no se administr imatinib.

40

Regulation of Na+ channels by luminal Na+ in rat cortical collecting tubule  

PubMed Central

The idea that luminal Na+ can regulate epithelial Na+ channels was tested in the cortical collecting tubule of the rat using whole-cell and single-channel recordings. Here we report results consistent with the idea of Na+ self-inhibition.Macroscopic amiloride-sensitive currents (INa) were measured by conventional whole-cell clamp. INa was a saturable function of external Na+ concentration ([Na+]o) with an apparent Km of 9 mm. Single channel currents (iNa) were measured in cell-attached patches. iNa increased with pipette Na+ concentration with an apparent Km of 48 mm. Since INa= (iNa)NPo, the different Km values imply that the channel density (N) and/or open probability (Po) increase as [Na+]o decreases. Reduction of [Na+]o after increasing intracellular Na+ concentration also increased the outward amiloride-sensitive conductance, consistent with activation of the Na+ channels.The underlying mechanism was studied by changing pipette Na+ concentration while recording from cell-attached patches. No increase in NPo was observed, suggesting that the effect is not a direct interaction between [Na+]o and the channel.[Na+]o was varied outside the patch-clamp pipette while recording from cell-attached patches. When amiloride was in the bath to prevent Na+ entry, no change in NPo was observed.Activation of the channels by hyperpolarization was observed with 140 mm Na+o but not with 14 mm Nao +.The results are consistent with the concept of self-inhibition of Na+ channels by luminal Na+. Activation of the channels by lowering [Na+]o is not additive with that achieved by hyperpolarization. PMID:9547389

Palmer, Lawrence G; Sackin, Henry; Frindt, Gustavo

1998-01-01

41

ROINN NA CEILTIS IS NA GIDHLIG / CELTIC AND GAELIC POSTGRADUATE STUDY IN 2014-15  

E-print Network

Brosnachaidh na Gidhlig / Gaelic Language Promotion Trust Margaret Callan, Urras Brosnachaidh na Gidhlig, cROINN NA CEILTIS IS NA GIDHLIG / CELTIC AND GAELIC POSTGRADUATE STUDY IN 2014-15 Taught degree (which can be written in English or Gaelic) Research degrees MRes (see separate sheet) One-year degree

Glasgow, University of

42

Intermitncia alfvnica gerada por caos na atmosfera solar e no vento solar  

NASA Astrophysics Data System (ADS)

Dados medidos no vento solar rpido proveniente dos buracos coronais revelam que os plasmas no meio interplanetrio so dominados por flutuaes Alfvnicas, caracterizadas por uma alta correlao entre as variaes do campo magntico e da velocidade do plasma. As flutuaes exibem muitas caractersticas esperadas em turbulncia magneto-hidrodinmica totalmente desenvolvida, tais como intermitncia e espectros contnuos. Contudo, os mecanismos responsveis pela evoluo de turbulncia Alfvnica intermitente no so completamente compreendidos. Neste trabalho a teoria de caos usada para explicar como sistemas Alfvnicos, modelados pela equao Schrdinger no-linear derivativa e pela equao Kuramoto-Sivashinsky, podem se tornar fortemente caticos medida em que parmetros do plasma so variados. Pequenas perturbaes no parmetro de dissipao podem fazer com que o sistema mude bruscamente de um regime peridico, ou fracamente catico, para um regime fortemente catico. As sries temporais das flutuaes do campo magntico nos regimes fortemente caticos exibem comportamento intermitente, em que fases laminares ou fracamente caticas so interrompidas por fortes estouros caticos. mostrado que o regime fortemente catico atingido quando as solues peridicas ou fracamente caticas globalmente estveis interagem com solues do sistema que so fortemente caticas, mas globalmente instveis. Estas solues globalmente instveis so conjuntos caticos no-atrativos conhecidos como selas caticas, e so responsveis pelos fortes estouros nos regimes intermitentes. Selas caticas tm sido detectadas experimentalmente em uma grande variedade de sistemas, sendo provvel que elas desempenhem um papel importante na turbulncia intermitente observada em plasmas espaciais.

Rempel, E. L.; Chian, A. C.-L.; Macau, E. E. N.; Rosa, R. R.

2003-08-01

43

Polmeros bioreabsorvveis na engenharia de tecidos  

Microsoft Academic Search

Resumo: A Engenharia de Tecidos consiste em um conjunto de conhecimentos e tcnicas para a reconstruo de novos rgos e tecidos. Baseada em conhecimentos das reas de cincia e engenharia de materiais, biolgica e mdica, a tcnica envolve a expanso in vitro de clulas viveis do paciente doador sobre suportes de polmeros bioreabsorvveis. O suporte degrada enquanto um novo rgo

Samuel H. Barbanti; Ceclia A. C. Zavaglia; Eliana A. R. Duek

2005-01-01

44

Redetermination of NaGdS2, NaLuS2 and NaYS2.  

PubMed

The title structures NaGdS2 (sodium gadolinium sulfide), NaLuS2 (sodium lutetium sulfide) and NaYS2 (sodium yttrium sulfide) were redetermined in order to improve the structural information available for the family of group 1 and thallium rare earth sulfides, which are isostructural with the rhombohedral ?-NaFeO2 structure type. In particular, the present investigation has been directed at the rhombohedral sodium rare earth sulfides. The observed dependence of the fractional coordinate z(S(2-)) on the identity of the rare earth element in the newly determined structures is in agreement with the known structures of the potassium and rubidium analogues. Crystals of NaGdS2 and NaLuS2 display obverse-reverse twinning. PMID:24898952

Fbry, Jan; Havlk, Lubomr; Ku?erkov, Monika; Duek, Michal

2014-06-01

45

The effect of Na vapor on the Na content of chondrules  

NASA Technical Reports Server (NTRS)

Chondrules contain higher concentrations of volatiles (Na) than expected for melt droplets in the solar nebula. Recent studies have proposed that chondrules may have formed under non-canonical nebular conditions such as in particle/gas-rich clumps. Such chondrule formation areas may have contained significant Na vapor. To test the hypothesis of whether a Na-rich vapor would minimize Na volatilization reaction rates in a chondrule analog and maintain the Na value of the melt, experiments were designed where a Na-rich vapor could be maintained around the sample. A starting material with a melting point lower that typical chondrules was required to keep the logistics of working with Na volatilization from NaCl within the realm of feasibility. The Knippa basalt, a MgO-rich alkali olivine basalt with a melting temperature of 1325 +/- 5 C and a Na2O content of 3.05 wt%, was used as the chondrule analog. Experiments were conducted in a 1 atm, gas-mixing furnace with the fO2 controlled by a CO/CO2 gas mixture and fixed at the I-W buffer curve. To determine the extent of Na loss from the sample, initial experiments were conducted at high temperatures (1300 C - 1350 C) for duration of up to 72 h without a Na-rich vapor present. Almost all (up to 98%) Na was volatilized in runs of 72 h. Subsequent trials were conducted at 1330 C for 16 h in the presence of a Na-rich vapor, supplied by a NaCl-filled crucible placed in the bottom of the furnace. Succeeding Knudsen cell weight-loss mass-spectrometry analysis of NaCl determined the P(sub Na) for these experimental conditions to be in the 10(exp -6) atm range. This value is considered high for nebula conditions but is still plausible for non-canonical environments. In these trials the Na2O content of the glass was maintained or in some cases increased; Na2O values ranged from 2.62% wt to 4.37% wt. The Na content of chondrules may be controlled by the Na vapor pressure in the chondrule formation region. Most heating events capable of producing chondrules are sufficient to volatile Na. Sodium volatilization reaction rates will be reduced to varying degrees from melt droplets, depending on the magnitude of the P(sub Na) generated. A combination of Na vapor during, and Na diffusion back into chondrules after, formation could maintain and/or enrich Na concentrations in chondrules.

Lewis, R. Dean; Lofgren, Gary E.; Franzen, Hugo F.; Windom, Kenneth E.

1993-01-01

46

The process of GaN single crystal growth by the Na flux method with Na vapor  

Microsoft Academic Search

Ga melts were heated in a boron nitride crucible at 800C and 5MPa of N2 for 8200h with Na vapor. Colorless and transparent prismatic GaN single crystals grew from a NaGa melt which was formed by dissolution of Na from the gas phase. Nitrogen was probably introduced into the melt with Na. The time dependence of the Na fraction (rNa=Na\\/(Na+Ga))

Takahiro Yamada; Hisanori Yamane; Hirokazu Iwata; Seiji Sarayama

2006-01-01

47

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

48

Deliquescence of NaClNaNO3, KNO3NaNO3, and NaClKNO3 salt mixtures from 90 to 120C  

PubMed Central

We conducted reversed deliquescence experiments in saturated NaClNaNO3H2O, KNO3NaNO3H2O, and NaClKNO3H2O systems from 90 to 120C as a function of relative humidity and solution composition. NaCl, NaNO3, and KNO3 represent members of dust salt assemblages that are likely to deliquesce and form concentrated brines on high-level radioactive waste package surfaces in a repository environment at Yucca Mountain, NV. Discrepancy between model prediction and experiment can be as high as 8% for relative humidity and 50% for dissolved ion concentration. The discrepancy is attributed primarily to the use of 25C models for ClNO3 and KNO3 ion interactions in the current Yucca Mountain Project high-temperature Pitzer model to describe the nonideal behavior of these highly concentrated solutions.

Carroll, Susan; Craig, Laura; Wolery, Thomas J

2005-01-01

49

The effect of NA vapor on the NA content of chondrules  

NASA Astrophysics Data System (ADS)

Chondrules contain higher concentrations of volatiles (Na) than expected for melt droplets in the solar nebula. Recent studies have proposed that chondrules may have formed under non-canonical nebular conditions such as in particle/gas-rich clumps. Such chondrule formation areas may have contained significant Na vapor. To test the hypothesis of whether a Na-rich vapor would minimize Na volatilization reaction rates in a chondrule analog and maintain the Na value of the melt, experiments were designed where a Na-rich vapor could be maintained around the sample. A starting material with a melting point lower that typical chondrules was required to keep the logistics of working with Na volatilization from NaCl within the realm of feasibility. The Knippa basalt, a MgO-rich alkali olivine basalt with a melting temperature of 1325 +/- 5 C and a Na2O content of 3.05 wt%, was used as the chondrule analog. Experiments were conducted in a 1 atm, gas-mixing furnace with the fO2 controlled by a CO/CO2 gas mixture and fixed at the I-W buffer curve. To determine the extent of Na loss from the sample, initial experiments were conducted at high temperatures (1300 C - 1350 C) for duration of up to 72 h without a Na-rich vapor present. Almost all (up to 98%) Na was volatilized in runs of 72 h. Subsequent trials were conducted at 1330 C for 16 h in the presence of a Na-rich vapor, supplied by a NaCl-filled crucible placed in the bottom of the furnace. Succeeding Knudsen cell weight-loss mass-spectrometry analysis of NaCl determined the PNa for these experimental conditions to be in the 10-6 atm range. This value is considered high for nebula conditions but is still plausible for non-canonical environments. In these trials the Na2O content of the glass was maintained or in some cases increased; Na2O values ranged from 2.62% wt to 4.37% wt. The Na content of chondrules may be controlled by the Na vapor pressure in the chondrule formation region. Most heating events capable of producing chondrules are sufficient to volatile Na. Sodium volatilization reaction rates will be reduced to varying degrees from melt droplets, depending on the magnitude of the PNa generated. A combination of Na vapor during, and Na diffusion back into chondrules after, formation could maintain and/or enrich Na concentrations in chondrules.

Lewis, R. Dean; Lofgren, Gary E.; Franzen, Hugo F.; Windom, Kenneth E.

1993-12-01

50

NA-NET numerical analysis net  

SciTech Connect

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

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

1991-12-01

51

NA-NET numerical analysis net  

SciTech Connect

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

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

1991-12-01

52

Painful Na-channelopathies: an expanding universe.  

PubMed

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

Waxman, Stephen G

2013-07-01

53

The NA62 RICH Detector  

NASA Astrophysics Data System (ADS)

The NA62 experiment is designed to measure the very rare kaon dacay K^+ rightarrow ?^+ ?bar? at the CERN SPS with a 10% accuracy. The Standard Model prediction for the branching ratio is (8.5 07) 10-11. One of the challenging aspect of the experiment is the suppression of the K+ ? ?+v? background at the 10-12 level. To satisfy this requirement a Ring Imaging Cherenkov Detector (RICH), able to separate pions from muons in the momentum range between 15 and 35 GeV/c, with a muon rejection factor better than 10-2, is needed. The RICH must also have a time resolution of about 100 ps to disentangle accidental time associations of beam particles with pions. The RICH will have a very long focal length (17 m) and will be filled with Ne gas at atmospheric pressure.

Cassese, A.

2014-06-01

54

NA62 Low Mass Spectrometer  

NASA Astrophysics Data System (ADS)

The NA62 experiment at CERN aims at a precision measurement of the ultra-rare decay K^+ rightarrow ?^+?bar?. A low mass ( 1.8%X0) spectrometer, whose construction is ongoing, has been designed to track charged kaon decays products. The system operates in vacuum, and will be operative in October 2014, when the first physics run is scheduled. The straw detector is made of 4 stations, each equipped with 1792 straws, arranged in 4 views (X, Y, U and V). A high aperture magnet (MNP33), placed between the second and the third chamber, provides a 0.36T dipole vertical B-field, required to measure the momentum of the charged particles. A 64-straws prototype was constructed in 2010. It was used as test bench for electronics commissioning and detector characterization. Time resolution and space-time relation were measured. A first test with a full chamber and final beam setup was performed in November 2012.

Palladino, V.

2014-06-01

55

Na(+) /Ca(2+) exchange and Na(+) /K(+) -ATPase in the heart.  

PubMed

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

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

2015-03-15

56

U Gorskome kotaru kao na Strawberry Hillu  

E-print Network

:// don-wolf.artistwebsites.com/. Trenutno radi na knjizi o djetinjstvu na Strawberry Hillu i iskustvima u Hrvatskoj s naslo- vom Nazvala me je gospodin Wolf. Q Don s jednom od svojih omiljenih fotografija: Hrvatska ?asna sestra hodaju?i po kii...

Boley, Colleen; Stakun, Rebecca; Novak, Charles; Pirnat-Greenberg, Marta

2012-07-01

57

Regulation of Na+ fluxes in plants  

PubMed Central

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

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

2014-01-01

58

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

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

59

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

PubMed

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. PMID:20590191

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

2010-06-28

60

Nedd4 mediates control of an epithelial Na+ channel in salivary duct cells by cytosolic Na+  

PubMed Central

Epithelial Na+ channels are expressed widely in absorptive epithelia such as the renal collecting duct and the colon and play a critical role in fluid and electrolyte homeostasis. Recent studies have shown that these channels interact via PY motifs in the C terminals of their ?, ?, and ? subunits with the WW domains of the ubiquitin-protein ligase Nedd4. Mutation or deletion of these PY motifs (as occurs, for example, in the heritable form of hypertension known as Liddles syndrome) leads to increased Na+ channel activity. Thus, binding of Nedd4 by the PY motifs would appear to be part of a physiological control system for down-regulation of Na+ channel activity. The nature of this control system is, however, unknown. In the present paper, we show that Nedd4 mediates the ubiquitin-dependent down-regulation of Na+ channel activity in response to increased intracellular Na+. We further show that Nedd4 operates downstream of Go in this feedback pathway. We find, however, that Nedd4 is not involved in the feedback control of Na+ channels by intracellular anions. Finally, we show that Nedd4 has no influence on Na+ channel activity when the Na+ and anion feedback systems are inactive. We conclude that Nedd4 normally mediates feedback control of epithelial Na+ channels by intracellular Na+, and we suggest that the increased Na+ channel activity observed in Liddles syndrome is attributable to the loss of this regulatory feedback system. PMID:9618557

Dinudom, A.; Harvey, K. F.; Komwatana, P.; Young, J. A.; Kumar, S.; Cook, D. I.

1998-01-01

61

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

NASA Astrophysics Data System (ADS)

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-? -S, pertussis toxin, and antibodies against the ? -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-.

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

1996-07-01

62

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

PubMed Central

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

Berret, Emmanuelle; Smith, Pascal Y.; Henry, Mlaine; Soulet, Denis; Hbert, Sbastien S.; Toth, Katalin; Mouginot, Didier; Drolet, Guy

2014-01-01

63

Programas del NCI: Anlisis molecular para la eleccin de tratamientos (MATCH) y MATCH para pacientes infantiles  

Cancer.gov

Informacin sobre el Programa de anlisis molecular para la eleccin de tratamientos (MATCH) del NCI, el cual asignar pacientes con tumores slidos y linfomas avanzados que hayan dejado de responder al tratamiento convencional a estudios clnicos de acuerdo con las anomalas genticas de sus tumores.

64

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

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 5106 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 ? -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 ( ? L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ? value for 21Na is 1379 e^2fm^4, while the resulting B( ? L) ? values for 20Na are 556 e^2fm^4 for the 3+ rightarrow 2+ , 35.75.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.1540.030 ?_ 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( ? L) values for the proton dripline nucleus 20Na .-1

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

65

NMR studies on Na+ transport in Synechococcus PCC 6311  

NASA Technical Reports Server (NTRS)

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%.

Nitschmann, W. H.; Packer, L.

1992-01-01

66

First-principles study of fast Na diffusion in Na3P  

NASA Astrophysics Data System (ADS)

We investigate the ionic conductivity and electronic properties of Na3P using first principle simulations. We found that the atoms were arranged in one layer of Na and P atoms and alternate layers containing Na atoms only. Three possible independent and asymmetric Na diffusion paths exist. In the first two, Na diffusion occurs among sodium atoms in the same layer, while in the third path, Na diffusion occurs among sodium atoms in different layers. Moreover, the activation energies of Na diffusion in the first two paths are much smaller than that of the third. With the introduction of a Na vacancy, a hole state deep in the valence region appears that is responsible for the valence band-edge rising in the center of the Brillouin zone. This sodium vacancy is very likely to play a role in the electron transfer in Na3P. The fast ionic conductivity and considerable electron conductivity make P a promising anode material in the first step of the Na deintercalation process.

Yu, Xue-fang; Giorgi, Giacomo; Ushiyama, Hiroshi; Yamashita, Koichi

2014-09-01

67

Characteristics and pharmacological regulation of epithelial Na+ channel (ENaC) and epithelial Na+ transport.  

PubMed

Epithelial Na(+) transport participates in control of various body functions and conditions: e.g., homeostasis of body fluid content influencing blood pressure, control of amounts of fluids covering the apical surface of alveolar epithelial cells at appropriate levels for normal gas exchange, and prevention of bacterial/viral infection. Epithelial Na(+) transport via the transcellular pathway is mediated by the entry step of Na(+) across the apical membrane via Epithelial Na(+) Channel (ENaC) located at the apical membrane, and the extrusion step of Na(+) across the basolateral membrane via the Na(+),K(+)-ATPase located at the basolateral membrane. The rate-limiting step of the epithelial Na(+) transport via the transcellular pathway is generally recognized to be the entry step of Na(+) across the apical membrane via ENaC. Thus, up-/down-regulation of ENaC essentially participates in regulatory systems of blood pressure and normal gas exchange. Amount of ENaC-mediated Na(+) transport is determined by the number of ENaCs located at the apical membrane, activity (open probability) of individual ENaC located at the apical membrane, single channel conductance of ENaC located at the apical membrane, and driving force for the Na(+) entry via ENaCs across the apical membrane. In the present review article, I discuss the characteristics of ENaC and how these factors are regulated. PMID:25242083

Marunaka, Yoshinori

2014-01-01

68

Characteristics and Pharmacological Regulation of Epithelial Na(+) Channel (ENaC) and Epithelial Na(+) Transport.  

PubMed

Epithelial Na(+) transport participates in control of various body functions and conditions: e.g., homeostasis of body fluid content influencing blood pressure, control of amounts of fluids covering the apical surface of alveolar epithelial cells at appropriate levels for normal gas exchange, and prevention of bacterial/viral infection. Epithelial Na(+) transport via the transcellular pathway is mediated by the entry step of Na(+) across the apical membrane via Epithelial Na(+) Channel (ENaC) located at the apical membrane, and the extrusion step of Na(+) across the basolateral membrane via the Na(+),K(+)-ATPase located at the basolateral membrane. The rate-limiting step of the epithelial Na(+) transport via the transcellular pathway is generally recognized to be the entry step of Na(+) across the apical membrane via ENaC. Thus, up-/down-regulation of ENaC essentially participates in regulatory systems of blood pressure and normal gas exchange. Amount of ENaC-mediated Na(+) transport is determined by the number of ENaCs located at the apical membrane, activity (open probability) of individual ENaC located at the apical membrane, single channel conductance of ENaC located at the apical membrane, and driving force for the Na(+) entry via ENaCs across the apical membrane. In the present review article, I discuss the characteristics of ENaC and how these factors are regulated. PMID:25152008

Marunaka, Yoshinori

2014-08-23

69

Catalysis of Na+ permeation in the bacterial sodium channel NaVAb  

PubMed Central

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

Chakrabarti, Nilmadhab; Ing, Christopher; Payandeh, Jian; Zheng, Ning; Catterall, William A.; Poms, Rgis

2013-01-01

70

Erythrocyte 22Na+ influx in hypertension  

SciTech Connect

We assessed 22Na+ uptake by erythrocytes (RBC) from 38 individuals with essential hypertension and 37 healthy controls. All subjects were male, white, non-obese and with normal renal function, obviating sex, race, hormonal, ponderal and renal factors known to influence RBC Na+ handling. The mean +/- sem 22Na+ uptake of the patients was 284 +/- 16 mumole/liter RBC/hour while that of normal controls was 249 +/- 11 mumole/liter RBC/hour; although the difference reached borderline significance, individual values showed considerable overlap. Consequently, in our population, RBC 22Na+ uptake is not a reliable marker for essential hypertension. We believe that previous studies should be reassessed with regard to patients' characteristics and future studies employ rigorous criteria in selection of subjects.

Shalev, O.; Eaton, J.W.; Ben-Ishay, D.

1984-01-01

71

Hydrogen-fluorine exchange in NaBH4-NaBF4.  

PubMed

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

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

2013-11-01

72

Characterization of Synthetic Na-Beidellite  

Microsoft Academic Search

Ahstract--Na-beidellite, a member of the smectite group, was grown hydrothermally from a gel of composition 0.35NazO.2.35A1zO3.7.3SiO2 in NaOH solutions at a pH between 7.5 and 13.5, a pressure of 1 kbar, and a temperature of 350\\

J. THEO K-LOPROGGE; BEN H. JANSEN; JOHN W. GEUS

1990-01-01

73

Deliquescence of NaCl-NaNO3, KNO3-NaNO3, and NaCl-KNO3 Salt Mixtures From 90 to 120?C  

SciTech Connect

We conducted reversed deliquescence experiments in saturated NaCl-NaNO{sub 3}-H{sub 2}O, KNO{sub 3}-NaNO{sub 3}-H{sub 2}O, and NaCl-KNO{sub 3}-H{sub 2}O systems from 90 to 120 C as a function of relative humidity and solution composition. NaCl, NaNO{sub 3}, and KNO{sub 3} represent members of dust salt assemblages that are likely to deliquesce and form concentrated brines on high-level radioactive waste package surfaces in a repository environment at Yucca Mountain, NV, USA. Discrepancy between model prediction and experimental code can be as high as 8% for relative humidity and 50% for dissolved ion concentration. The discrepancy is attributed primarily to the use of 25 C models for Cl-NO{sub 3} and K-NO{sub 3} ion interactions in the current Yucca Mountain Project high-temperature Pitzer model to describe the non-ideal behavior of these highly concentrated solutions.

Carroll, S A; Craig, L; Wolery, T J

2004-10-20

74

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

75

Inactivation of Rb+ and Na+ occlusion on (Na+,K+)-ATPase by modification of carboxyl groups.  

PubMed

This paper demonstrates and characterizes inactivation by N,N'-dicyclohexylcarbodiimide (DCCD) of Rb+ and Na+ occlusion in pig kidney (Na+,K+)-ATPase. Rb+ and Na+ occlusion dependent on oligomycin are measured with a manual assay. Parallel measurement of phosphorylation (by Pi plus ouabain) and Na+ or Rb+ occlusion lead to stoichiometries of 3 Na+ or 2 Rb+ per pump molecule. Inactivation of cation occlusion by DCCD shows the following features: (a) Rb+ and Na+ occlusion are inactivated with identical rates and (b) DCCD concentration dependence shows first-order kinetics and also proportionality to the ratio of DCCD to protein, (c) Rb+ and Na+ occlusion are equally protected from DCCD, by Rb+ ions with high affinity (or Na+ ions with lower affinity), (d) inactivation is only slightly pH-dependent between 6 and 8.5 but (e) is significantly accelerated by several hydrophobic amines while a water-soluble nucleophile, glycine ethyl ester has no effect, and (f) inactivation is exactly correlated with inactivation of (Na+,K+)-ATPase activity of ATP-dependent Na+/K+ exchange in reconstituted vesicles and with the magnitude of E1Na+----E2(Rb+) conformational transitions measured with fluorescence probes. The simplest hypothesis to explain the results is that DCCD modifies one (or a small number of) critical carboxyl residues in a non-aqueous cation binding domain and so blocks occlusion of 2 Rb+ or 3 Na+ ions. The results suggest further that Na+ and K+(Rb+) bind to the same sites and are transported sequentially on the same trans-membrane segments. A second effect of the DCCD treatment is a 4-8-fold shift of the conformational equilibrium E2(Rb+)----E1Rb+ toward E1Rb+. This is detected by (a) reduction in apparent Rb+ affinity for Rb+ occlusion or Rb+/Rb+ exchange in vesicles and (b) direct demonstration of an increased rate of E2(K+)----E1Na+ and decreased rate of E1Na+----E2(K+). This effect is not protected against by Rb+ ions and probably reflects modification of a second group of residues. Modification of (Na+,K+)-ATPase by carbodiimides is complex. Depending on the nature of the carbodiimide (water- or lipid-soluble), ratio of carbodiimide to protein, and perhaps source of the enzyme, inactivation might result either from modification of critical carboxyls, as suggested by this work, or from internal cross-linking as proposed by Pedemonte, C. H. and Kaplan, J. H. ((1986) J. Biol. Chem. 261, 3632-3639). PMID:2848822

Shani-Sekler, M; Goldshleger, R; Tal, D M; Karlish, S J

1988-12-25

76

El NCI inicia un estudio para evaluar la utilidad de la secuenciacin gentica para mejorar los resultados en los pacientes  

Cancer.gov

El Instituto Nacional del Cncer (NCI) lanzar este mes un estudio clnico piloto denominado M-PACT con la finalidad de evaluar si el tratamiento asignado segn mutaciones genticas especficas puede brindar beneficios a pacientes con tumores slidos metastsicos.

77

Nonresonant charge-capture - Na/+/ + Li reversibly proceeding to Na + Li/+/.  

NASA Technical Reports Server (NTRS)

The cross sections for the process Na(+) + Li reversibly proceeding to Na + Li(+) are calculated in the range from 100 eV to 12 keV using a perturbed stationary state formulation, and are found to agree with experiment to the extent of reproducing detailed structure. A simple interpretation is presented of the observed quasi-oscillatory structure.

Bottcher, C.; Oppenheimer, M.

1972-01-01

78

Na-ion dynamics in Quasi-1D compound NaV2O4  

NASA Astrophysics Data System (ADS)

We have used the pulsed muon source at ISIS to study high-temperature Na-ion dynamics in the quasi-one-dimensional (Q1D) metallic antiferromagnet NaV2O4. By performing systematic zero-field and longitudinal-field measurements as a function of temperature we clearly distinguish that the hopping rate increases exponentially above Tdiff ? 250 K. The data is well fitted to an Arrhenius type equation typical for a diffusion process, showing that the Na-ions starts to be mobile above Tdiff. Such results make this compound very interesting for the tuning of Q1D magnetism using atomic-scale ion-texturing through the periodic potential from ordered Na-vacancies. Further, it also opens the door to possible use of NaV2O4 and related compounds in energy related applications.

Mnsson, M.; Umegaki, I.; Nozaki, H.; Higuchi, Y.; Kawasaki, I.; Watanabe, I.; Sakurai, H.; Sugiyama, J.

2014-12-01

79

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

E-print Network

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

Clapham, David E.

80

Functional coupling of renal K+ and Na+ handling causes high blood pressure in Na+ replete mice  

PubMed Central

A network of kinases, including WNKs, SPAK and Sgk1, is critical for the independent regulation of K+ and Na+ transport in the distal nephron. Angiotensin II is thought to act as a key hormone in orchestrating these kinases to switch from K+ secretion during hyperkalaemia to Na+ reabsorption during intravascular volume depletion, thus keeping disturbances in electrolyte and blood pressure homeostasis at a minimum. It remains unclear, however, how K+ and Na+ transport are regulated during a high Na+ intake, which is associated with suppressed angiotensin II levels and a high distal tubular Na+ load. We therefore investigated the integrated blood pressure, renal, hormonal and gene and protein expression responses to large changes of K+ intake in Na+ replete mice. Both low and high K+ intake increased blood pressure and caused Na+ retention. Low K+ intake was accompanied by an upregulation of the sodium-chloride cotransporter (NCC) and its activating kinase SPAK, and inhibition of NCC normalized blood pressure. Renal responses were unaffected by angiotensin AT1 receptor antagonism, indicating that low K+ intake activates the distal nephron by an angiotensin-independent mode of action. High K+ intake was associated with elevated plasma aldosterone concentrations and an upregulation of the epithelial sodium channel (ENaC) and its activating kinase Sgk1. Surprisingly, high K+ intake increased blood pressure even during ENaC or mineralocorticoid receptor antagonism, suggesting the contribution of aldosterone-independent mechanisms. These findings show that in a Na+ replete state, changes in K+ intake induce specific molecular and functional adaptations in the distal nephron that cause a functional coupling of renal K+ and Na+ handling, resulting in Na+ retention and high blood pressure when K+ intake is either restricted or excessively increased. PMID:24396058

Vitzthum, Helga; Seniuk, Anika; Schulte, Laura Helene; Mller, Maxie Luise; Hetz, Hannah; Ehmke, Heimo

2014-01-01

81

Influence of respiratory function parameters on the quality of life of COPD patients* Influncia dos parmetros funcionais respiratrios na qualidade de vida de pacientes com DPOC  

Microsoft Academic Search

Objective: To determine the quality of life of COPD patients by using the Medical Outcomes 36-item Short-Form Survey (SF-36) and the Saint George's Respiratory Questionnaire (SGRQ), correlating the scores with respiratory function parameters. Methods: This was a cross-sectional study involving 42 COPD patients. We used the SGRQ (a specific questionnaire) and the SF-36 (a general questionnaire), together with their component

Eanes Delgado; Barros Pereira; Renata Pinto; Marcelo Alcantara; Marta Medeiros; Rosa Maria Salani Mota

82

Nae zkuenosti s operac podle Lapiduse u pacient? s hallux valgus Our Results of the Lapidus Procedure in Patients with Hallux Valgus Deformity  

Microsoft Academic Search

PURPOSE OF THE STUDY The most frequent deformity of the big toe and forefoot associated with a collapse of the transverse arch of the foot is av algus deformity. For correction of a hallux valgus, several procedures are described in the literature. A valgus deformi- ty often develops due to a varus deviation of the first metatarsal bone when the

S. POPELKA; P. VAV?K; R. HROMDKA; A. SOSNA

2008-01-01

83

Targeting voltage gated sodium channels NaV1.7, Na V1.8, and Na V1.9 for treatment of pathological cough.  

PubMed

Recent advances in our understanding of voltage-gated sodium channels (NaVs) lead to the rational hypothesis that drugs capable of selective blockade of NaV subtypes may be a safe and effective strategy for the treatment of unwanted cough. Among the nine NaV subtypes (NaV1.1-NaV1.9), the afferent nerves involved in initiating cough, in common with nociceptive neurons in the somatosensory system, express mainly NaV1.7, NaV1.8, and NaV1.9. Although knowledge about the effect of selectively blocking these channels on the cough reflex is limited, their biophysical properties indicate that each may contribute to the hypertussive and allotussive state that typifies subacute and chronic nonproductive cough. PMID:24272479

Muroi, Yukiko; Undem, Bradley J

2014-02-01

84

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

PubMed

The mechanism of fluid transport across corneal endothelium remains unclear. We examine here the relative contributions of cellular mechanisms of Na+ transport and the homeostasis of intracellular [Na+] in cultured bovine corneal endothelial cells, and the influence of ambient Na+ and HCO3- on the deturgescence of rabbit cornea. Bovine corneal endothelial cells plated on glass coverslips were incubated for 60 min with 10 microm of the fluorescent Na+ indicator SBFI precursor in HCO3- HEPES (BH) Ringer's solution. After loading, cells were placed in a perfusion chamber. Indicator fluorescence (490 nm) was determined with a Chance-Legallais time-sharing fluorometer. Its voltage output was the ratio of the emissions excited at 340 and 380 nm. For calibration, cells were treated with gramicidin D. For fluid transport measurements, rabbit corneas were mounted in a Dikstein-Maurice chamber, and stromal thickness was measured with a specular microscope. The steady-state [Na+]i in BH was 14.36+/-0.38 mM (n = mean+/-s.e.). Upon exposure to Na+ -free BH solution (choline substituted), [Na+]i decreased to 1.81+/-0.20mM (n = 19). When going from Na+ -free plus 100 microm ouabain to BH plus ouabain, [Na+]i increased to 46.17+/-2.50 (n = 6) with a half time of 1.26+/-0.04 min; if 0.1 microm phenamil plus ouabain were present, it reached only 21.78+/-1.50mm. The exponential time constants (min-1) were: 0.56+/-0.04 for the Na+ pump; 0.39+/-0.01 for the phenamil sensitive Na+ channel; and 0.17+/-0.02 for the ouabain-phenamil-insensitive pathways. In HCO3- free medium (gluconate substituted), [Na+]i was 14.03+/-0.11mM; upon changing to BH medium, it increased to 30.77+/-0.74 mm. This last [Na+]i increase was inhibited 66% by 100 microm DIDS. Using BH medium, corneal thickness remained nearly constant, increasing at a rate of only 2.9+/-0.9 microm hr-1 during 3 hr. However, stromal thickness increased drastically (swelling rate 36.1+/-2.6 microm hr-1) in corneas superfused with BH plus 100 microm ouabain. Na+ -free, HCO3- free solution and 100 microm DIDS also led to increased corneal swelling rates (17.7+/-3.6, 14.4+/-1.6 and 14.9+/-1.2 microm hr-1, respectively). The present results are explained by the presence of a DIDS-inhibitable Na+-HCO3- cotransporter and an epithelial Na+ channel, both previously found in these cells. On the other hand, the quantitative picture presented here appears a novelty. The changes we observe are consistent with pump-driven rapid exchange of intracellular Na+, and recirculation of fully 70% of the Na+ pump flux via apical Na+ channels. PMID:15183104

Kuang, Kunyan; Li, Yansui; Yiming, Maimaiti; Snchez, Jos M; Iserovich, Pavel; Cragoe, E J; Diecke, Friedrich P J; Fischbarg, Jorge

2004-07-01

85

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

PubMed

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

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

2015-01-01

86

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

NASA Astrophysics Data System (ADS)

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) , rNaC = 2.379(15) , rN12N = 2.233(15) , 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.

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

87

The role of Na/+/ in transport processes of bacterial membranes  

NASA Technical Reports Server (NTRS)

Until recently it was generally held that transport in bacteria was linked exclusively to proton circulation, in contrast to most eucaryotic systems, which depended on Na(+) circulation. The present review is intended to trace recent developments which have led to the discarding of this idea. The discussion covers transport of Na(+) and other cations, effects of Na(+) and Na(+) gradients on metabolite transport, properties of Na(+)-dependent transport carriers, and evolutionary considerations of Na(+) transport. It is now apparent that the transport of Na(+) is an important part of energy metabolism in bacteria, and that Na(+) gradients as well as H(+) gradients are used in these systems for the conservation and transmission of energy. Two hypotheses are proposed to explain the evolution of Na/K systems, and it is presently difficult to decide between them.

Lanyi, J. K.

1979-01-01

88

OCENA PODATNO ?CI PATKW OWSIANYCH NA KRUSZENIE  

Microsoft Academic Search

S t r e s z c z e n i e . Celem pracy byo okre ?lenie wytrzymao ?ci kinetycznej patkw owsianych byskawicznych. W pracy przedstawiono zakres zmian ksztatu i struktury badanych patkw pod k?tem oceny ich podatno ?ci na kruszenie podczas testowania w testerze pneumatycznym i mecha- nicznym. Uzyskane wyniki bada ? obejmuj? zmiany cech geometrycznych patkw, jakie

Marian Panasiewicz; Agnieszka Misiura

89

master's degree NaNotechNology  

E-print Network

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

Twente, Universiteit

90

Laser trapping of {sup 21}Na atoms  

SciTech Connect

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

Lu, Zheng-Tian

1994-09-01

91

Sodium thioether macrocyclic chemistry: remarkable homoleptic octathia coordination to na(.).  

PubMed

Unprecedented homoleptic octathioether macrocyclic coordination to Na(+) in [Na([24]aneS8)](+) has been achieved by using Na[B{3,5-(CF3)2-C6H3}4] as a source of "naked" Na(+) ions and confirmed crystallographically, with d(Na-S) = 2.9561(15)-3.0524(15) . Density functional theory calculations show that there is electron transfer from the S 3p and C 2p valence orbitals of the ligand to the 3s and 3p orbitals of the Na(+) ion upon complexation. PMID:25723901

Champion, Martin J D; Dyke, John M; Levason, William; Light, Mark E; Pugh, David; Bhakhoa, Hanusha; Rhyman, Lydia; Ramasami, Ponnadurai; Reid, Gillian

2015-03-16

92

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

PubMed Central

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

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

2012-01-01

93

1a. Fase 2a. Fase 3a. Fase 4a. Fase 5a. Fase 6a. Fase 7a. Fase 8a. Fase 9a. Fase Sade Pblica I 54 Sade Pblica II 54 Fisioterapia I 108 Farmacologia I 72  

E-print Network

Ortopedia II 72 450 Morfofisiologia 108 Bioqumica Bsica 72 Cinesiologia II 108 Cinesioterapia I 90 Fisioterapia em Reumatologia I 72 Fisioterapia em Traumoto Ortopedia I 72 Fisioterapia em Procedimentos Pr e

Floeter, Sergio Ricardo

94

Kinetics of Na(+)-dependent conformational changes of rabbit kidney Na+,K(+)-ATPase.  

PubMed Central

The kinetics of Na(+)-dependent partial reactions of the Na+,K(+)-ATPase from rabbit kidney were investigated via the stopped-flow technique, using the fluorescent labels N-(4-sulfobutyl)-4-(4-(p-(dipentylamino)phenyl)butadienyl)py ridinium inner salt (RH421) and 5-iodoacetamidofluorescein (5-IAF). When covalently labeled 5-IAF enzyme is mixed with ATP, the two labels give almost identical kinetic responses. Under the chosen experimental conditions two exponential time functions are necessary to fit the data. The dominant fast phase, 1/tau 1 approximately 155 s-1 for 5-IAF-labeled enzyme and 1/tau 1 approximately 200 s-1 for native enzyme (saturating [ATP] and [Na+], pH 7.4 and 24 degrees C), is attributed to phosphorylation of the enzyme and a subsequent conformational change (E1ATP(Na+)3-->E2P(Na+)3 + ADP). The smaller amplitude slow phase, 1/tau 2 = 30-45 s-1, is attributed to the relaxation of the dephosphorylation/rephosphorylation equilibrium in the absence of K+ ions (E2P<==>E2). The Na+ concentration dependence of 1/tau 1 showed half-saturation at a Na+ concentration of 6-8 mM, with positive cooperatively involved in the occupation of the Na+ binding sites. The apparent dissociation constant of the high-affinity ATP-binding site determined from the ATP concentration dependence of 1/tau 1 was 8.0 (+/- 0.7) microM. It was found that P3-1-(2-nitrophenyl)ethyl ATP, tripropylammonium salt (NPE-caged ATP), at concentrations in the hundreds of micromolar range, significantly decreases the value of 1/tau 1, observed. This, as well as the biexponential nature of the kinetic traces, can account for previously reported discrepancies in the rates of the reactions investigated. PMID:9726935

Clarke, R J; Kane, D J; Apell, H J; Roudna, M; Bamberg, E

1998-01-01

95

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

NASA Technical Reports Server (NTRS)

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.

Cherng, Jing-Yih; Bennion, Douglas N.

1987-01-01

96

Na Partitioning During Thermomechanical Processing of an Mg-Sn-Zn-Na Alloy  

NASA Astrophysics Data System (ADS)

Microstructural characterization was used to examine the changes that occur in an Mg-6Sn-5Zn-0.3Na alloy from casting to extrusion at either 623 K or 723 K (350 C or 450 C) followed by artificial aging at 473 K (200 C). In particular, the partitioning of Na was examined at each step using STEM-EDS mapping. Na atoms were found to preferentially partition to the Mg-Zn phase when present. After extrusion, when no Mg-Zn was observed, the spherical Mg2Sn particles were found to be enriched in Na, particularly at the higher extrusion temperature. Artificial aging following extrusion resulted in a change in Na partitioning, and a coarse distribution of Mg-Zn precipitate rods. Na microadditions led to a high as-extruded hardness, but a significant tension-compression yield asymmetry was still observed at room temperature. The compressive yield strength was found to decrease significantly after 1000 hours of aging.

TerBush, Jessica R.; Stanford, Nicole; Nie, Jian-Feng; Barnett, Matthew R.

2013-11-01

97

Conduction of Na+ and K+ through the NaK channel: molecular and Brownian dynamics studies.  

PubMed

Conduction of ions through the NaK channel, with M0 helix removed, was studied using both Brownian dynamics and molecular dynamics. Brownian dynamics simulations predict that the truncated NaK has approximately a third of the conductance of the related KcsA K+ channel, is outwardly rectifying, and has a Michaelis-Menten current-concentration relationship. Current magnitude increases when the glutamine residue located near the intracellular gate is replaced with a glutamate residue. The channel is blocked by extracellular Ca2+. Molecular dynamics simulations show that, under the influence of a strong applied potential, both Na+ and K+ move across the selectivity filter, although conduction rates for Na+ ions are somewhat lower. The mechanism of conduction of Na+ differs significantly from that of K+ in that Na+ is preferentially coordinated by single planes of pore-lining carbonyl oxygens, instead of two planes as in the usual K+ binding sites. The water-containing filter pocket resulting from a single change in the selectivity filter sequence (compared to potassium channels) disrupts several of the planes of carbonyl oxygens, and thus reduces the filter's ability to discriminate against sodium. PMID:18456826

Vora, Taira; Bisset, David; Chung, Shin-Ho

2008-08-01

98

Computational interpretation of 23Na MQMAS NMR spectra: A comprehensive investigation of the Na environment in silicate glasses  

NASA Astrophysics Data System (ADS)

Molecular dynamics, density functional theory calculations and 23Na NMR experiments have been used to inspect the chemical and structural characteristics of the Na environment in soda-lime silicate (CSN) and aluminosilicate (CASN) glasses. The use of an improved 3QMAS pulse sequence has allowed a clear identification of different Na sites. Average coordination numbers have been extracted by fitting the 23Na 3QMAS spectra with the computed NMR parameters. The results show that the 23Na ?iso values correlate with the average <Na-O> distances only when the different coordination numbers are explicitly taken into account.

Gambuzzi, Elisa; Charpentier, Thibault; Menziani, Maria Cristina; Pedone, Alfonso

2014-09-01

99

Avaliao do ndice de temperatura de globo negro e umidade e desempenho de sunos nas fases de crescimento e terminao criados em sistemas em camas sobrepostas em condies de vero  

Microsoft Academic Search

RESUMO - Um estudo foi realizado com o objetivo de avaliar o sistema de criao em camas sobrepostas de maravalha e de casca de arroz, em comparao ao piso tradicional de concreto e sua influncia no desempenho dos animais com base no ITGU (ndice de Temperatura de Globo negro e Umidade), no ganho de peso, no consumo de rao, na

Ilda de Ftima Ferreira Tinco; Ceclia de Ftima Souza; Paulo Armando Victoria de Oliveira; Robson Mendes de Paulo; Josiane Aparecida Campos; Cinara da Cunha Siqueira Carvalho; Marcelo Bastos Cordeiro

2007-01-01

100

Nac onal~na akadem nauk Ukra ni KONDENSOVANIH  

E-print Network

baga- tokomponentno sistemi zar d enih tverdih sfer, wo otrimane metodom ner vnova nogo statistiqnogo tiqnost na malih v dstan h. Qisel~n rozrahunki dl zsuvno v' zkost ta teploprov dnost na osnov normal~nogo

101

Rescue of na+ affinity in aspartate 928 mutants of na+,k+-ATPase by secondary mutation of glutamate 314.  

PubMed

The Na(+),K(+)-ATPase binds Na(+) at three transport sites denoted I, II, and III, of which site III is Na(+)-specific and suggested to be the first occupied in the cooperative binding process activating phosphorylation from ATP. Here we demonstrate that the asparagine substitution of the aspartate associated with site III found in patients with rapid-onset dystonia parkinsonism or alternating hemiplegia of childhood causes a dramatic reduction of Na(+) affinity in the ?1-, ?2-, and ?3-isoforms of Na(+),K(+)-ATPase, whereas other substitutions of this aspartate are much less disruptive. This is likely due to interference by the amide function of the asparagine side chain with Na(+)-coordinating residues in site III. Remarkably, the Na(+) affinity of site III aspartate to asparagine and alanine mutants is rescued by second-site mutation of a glutamate in the extracellular part of the fourth transmembrane helix, distant to site III. This gain-of-function mutation works without recovery of the lost cooperativity and selectivity of Na(+) binding and does not affect the E1-E2 conformational equilibrium or the maximum phosphorylation rate. Hence, the rescue of Na(+) affinity is likely intrinsic to the Na(+) binding pocket, and the underlying mechanism could be a tightening of Na(+) binding at Na(+) site II, possibly via movement of transmembrane helix four. The second-site mutation also improves Na(+),K(+) pump function in intact cells. Rescue of Na(+) affinity and Na(+) and K(+) transport by second-site mutation is unique in the history of Na(+),K(+)-ATPase and points to new possibilities for treatment of neurological patients carrying Na(+),K(+)-ATPase mutations. PMID:25713066

Holm, Rikke; Einholm, Anja P; Andersen, Jens P; Vilsen, Bente

2015-04-10

102

Na(2+x)Ti6O13 as potential negative electrode material for Na-ion batteries.  

PubMed

Na-ion batteries provide one of the most promising alternatives for Li-ion batteries due to the high abundance and low cost of Na. The strongly electropositive character of Na enables almost comparable cell potentials. Here we show that by lowering the cutoff voltage from 0.3 to 0 V vs Na/Na(+) the capacity of the Na2Ti6O13 negative electrode material can be enhanced from 49.5 mAh/g (Na(2+1)Ti6O13) to a promising 196 mAh/g (Na(2+4)Ti6O13) for at least 10 cycles, after which it gradually reduces. To understand the structural changes in situ X-ray diffraction is performed and compared with density functional theory calculations. A consistent picture of the evolution in lattice parameters and Na-ion positions is presented. The results show that Na-ion intercalation in the Na(2+x)Ti6O13 host structure is limited to Na(2+2)Ti6O13 and proceeds through a solid solution reaction. Only small changes in lattice parameters promote that the insertion reaction is highly reversible. Further increasing the Na composition below 0.3 V appears to lead to loss in crystallinity, which in combination with solid electrolyte interface formation is suggested to be the origin of the gradually reducing reversible capacity. PMID:25079946

Shen, Kun; Wagemaker, Marnix

2014-08-18

103

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

104

Slip casting alumina with Na-CMC  

SciTech Connect

Many forming methods are in common use for engineering ceramics. Of these, slip casting is an ideal forming method because of its low cost, simplicity and flexibility, potential for uniform particle packing and suitability to the production of articles of intricate shape. Slip casting nonclay materials, such as alumina, requires the use of both a deflocculant and a binder. There are many commercially available deflocculants and binders that can be tested in alumina casting slips. However, determination of a suitable deflocculant/binder combination and quantification of the optimal additions of the deflocculant/binder pair can be time consuming. Certain deflocculants are capable of acting as binders. One such additive is sodium carboxymethylcellulose (Na-cmc), a cellulose ether. Na-cmc is a powerful binder. It is a member of the carbohydrate binder group--the binder group with the strongest binding power. It is capable of acting as a deflocculant in glazes and nonclay casting slips.

Ruys, A.J.; Sorrell, C.C. [Univ. of New South Wales, Sydney, New South Wales (Australia)

1996-11-01

105

Rat hepatocytes exhibit basolateral Na+\\/HCO- cotransport  

Microsoft Academic Search

Primary cultures and plasma membrane vesicles were used to characterize Na+ and HCO3- transport by rat hepatocytes. Na+ uptake into hepatocytes was stimulated approximately 10-fold by 25 mM extracellular HCO3-.HCO3--stimulated Na+ uptake was saturable, abolished by 4-acetamido-4'-isothiocyano-2,2'-disulfonic acid stilbene (SITS), and unaffected by amiloride or Cl- removal. Neither propionate nor acetate reproduced this effect of HCO3-. 22Na efflux from preloaded

E. L. Renner; J. R. Lake; B. F. Scharschmidt; B. Zimmerli; P. J. Meier

1989-01-01

106

Igneous origin for the Na in the cloud of Io  

NASA Technical Reports Server (NTRS)

Mixtures of sulfur and Na-bearing silicates were heated in evacuated silica glass capsules to temperatures between 600 C and 950 C. At or above 850 C, Na-silicate glass reacts with elemental S to form a (Na, K) sulfide. Mobilization of this phase may account for the presence of Na and K on the surface of Io, and hence in the material sputtered onto the Jovian magnetosphere.

Johnson, Mary L.; Burnett, D. S.

1990-01-01

107

Transport of Na + inside the giant axon of squid  

Microsoft Academic Search

The transport mechanism of Na ions within the nerve cell was studied by measuring the radioactivity distribution profile of22Na that had been intracellularly injected into the giant axon. Specifically, we tested whether or not the movement of Na ions\\u000a is coupled with the process of fast axonal transport. Results of our measurements indicate that the intracellular transport\\u000a of Na+ and

Donald C. Chang

1985-01-01

108

Pojem nekone#na pou##vaj# matematici t#m## odjak#iva. Vzpome#me nap#. na Z#n#na (asi 480 --430) a jeho #lohu o Achillovi a #elv#, #i na #vahy #ek# o tom, #e  

E-print Network

D#L I. Pojem nekone#na pou##vaj# matematici t#m## odjak#iva. Vzpome#me nap#. na Z#n#na (asi 480#jak# #innosti #i vlastnosti (tzv. potenci#ln# forma nekone#na) --- nap#. #Achilles #elvu nikdy nedohon##, #po#my t#kaj#c# se zna#n# slo#it#ch ##st# re#ln# p##mky, nap#. p#i vy#et#ov#n# defini#n#ch obor# funkc

Stanovsky, David

109

The Rapid-onset Dystonia Parkinsonism Mutation D923N of the Na+,K+-ATPase ?3 Isoform Disrupts Na+ Interaction at the Third Na+ Site*  

PubMed Central

Rapid-onset dystonia parkinsonism (RDP), a rare neurological disorder, is caused by mutation of the neuron-specific ?3-isoform of Na+,K+-ATPase. Here, we present the functional consequences of RDP mutation D923N. Relative to the wild type, the mutant exhibits a remarkable ?200-fold reduction of Na+ affinity for activation of phosphorylation from ATP, reflecting a defective interaction of the E1 form with intracellular Na+. This is the largest effect on Na+ affinity reported so far for any Na+,K+-ATPase mutant. D923N also affects the interaction with extracellular Na+ normally driving the E1P to E2P conformational transition backward. However, no impairment of K+ binding was observed for D923N, leading to the conclusion that Asp923 is specifically associated with the third Na+ site that is selective toward Na+. The crystal structure of the Na+,K+-ATPase in E2 form shows that Asp923 is located in the cytoplasmic half of transmembrane helix M8 inside a putative transport channel, which is lined by residues from the transmembrane helices M5, M7, M8, and M10 and capped by the C terminus, recently found involved in recognition of the third Na+ ion. Structural modeling of the E1 form of Na+,K+-ATPase based on the Ca2+-ATPase crystal structure is consistent with the hypothesis that Asp923 contributes to a site binding the third Na+ ion. These results in conjunction with our previous findings with other RDP mutants suggest that a selective defect in the handling of Na+ may be a general feature of the RDP disorder. PMID:20576601

Einholm, Anja Pernille; Toustrup-Jensen, Mads S.; Holm, Rikke; Andersen, Jens Peter; Vilsen, Bente

2010-01-01

110

Sources of Na for the Io atmosphere  

NASA Technical Reports Server (NTRS)

The physics and geology of Io have been extensively studied, but there has been little discussion of the chemistry. Relatively little is known about Io chemistry, but there are constraints. Further, it will be a long time before improvements will result from direct observation, given the severe difficulties with the Galileo mission. Via laboratory simulation experiments, plausible thermochemical and photochemical processes which determine the nature and amounts of surface constituents of Io are explored. The well-known density of Io shows that the planet overall is rocky. Because the orbit of Io is well within the magnetosphere of Jupiter and because Io only has a thin, transient SO2 atmosphere, the surface is continually sputtered with magnetospheric ions. Complex processes ionize and accelerate the Io surface atoms to keV and MeV energies. Remarkably, only S, O, and Na ions were found by Voyager. Sputtering also produces an atomic cloud of Na and S (O not observable) with a trace of K. Both gaseous and solid SO2 are known from spectroscopic studies. A trace of H2S and possibly CO2 are present. Geologic features are interpreted in terms of elemental S, but there is no direct evidence for this constituent. We thus have a rocky planet which does not have rocks on the surface. Our general goal is to understand the cycling of Na, S, and O through the crust and atmosphere on present-day Io and to understand how Io evolved to this state. A specific objective was to determine the phases on the surface which are the source of the Na in the atmosphere of Io.

Burnett, D. S.; Ellis, Susan B.; Rice, A.; Epstein, S.

1993-01-01

111

Matter radii of Na and Mg isotopes  

Microsoft Academic Search

The interaction cross sections (?I) of ANa (A = 2023, 2532) and AMg (A = 20, 2225, 27, 2933) on carbon target have been measured at a beam energy of around 950 A MeV. The effective root-mean-square matter radii of these isotopes were deduced from ?I by a Glauber-type calculation. Combining the isotope-shift data with the present Na data the

T. Suzuki; H. Geissel; O. Bochkarev; L. Chulkov; M. Golovkov; D. Hirata; H. Irnich; Z. Janas; H. Keller; T. Kobayashi; G. Kraus; G. Muenzenberg; S. Neumaier; F. Nickel; A. Ozawa; A. Piechaczeck; E. Roeckl; W. Schwab; K. Suemmerer; K. Yoshida; I. Tanihata

1997-01-01

112

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

Microsoft Academic Search

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

Orlie Levy; Antonio De la Vieja; Nancy Carrasco

1998-01-01

113

Influence of Salt Purity on Na+ and Palmitic Acid Interactions  

E-print Network

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

114

Electrochemical Properties of Monoclinic NaNiO2  

E-print Network

Monoclinic NaNiO[subscript 2] is re-investigated as a positive electrode material for sodium ion batteries. We observe reversible Na extraction and insertion of about 120 mAh/g when NaNiO[subscript 2] is cycled between ...

Vassilaras, Plousia E.

115

Reich e a possibilidade do bem-estar na cultura  

Microsoft Academic Search

Numa entrevista dada em 1952, Reich afirmou que o texto freudiano O mal-estar na cultura fora escrito em resposta a uma conferncia que proferira na casa do Fre ud sobre o tema profilaxia das neuroses. Inspirado nesse depoimento, este trabalho procura investigar as teses reichianas que se contrapem ao pensamento freudiano de O mal -estar na cultura. Diferenciam-se as posies

Paulo Albertini

2003-01-01

116

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

PubMed Central

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+ pumpmediated proton inflow may have any physiological or pathophysiological significance remains to be clarified. PMID:24688018

Vedovato, Natascia

2014-01-01

117

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

E-print Network

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

Yu, K.N.

118

Na insertion mechanisms in vanadium oxide nanotubes for na-ion batteries.  

PubMed

In this study, we successfully synthesized lamellar-structured Ni0.1VOx NTs by a microwave-assisted hydrothermal method and cation exchange reaction. High initial discharge capacity and 100% efficiency were obtained when the Ni0.1VOx NTs cathode was used as a cathode material for the Na battery. The intercalation mechanism and capacity fading effect were investigated in detail both experimentally using Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses and theoretically using the ab initio simulation method. During the intercalation of Na(+) into VOx NT structures, TEM, XRD, FT-IR, and XPS data revealed the cointercalation of the solvent, resulting in the expansion of the interlayer spacing and carbon and oxygen adsorption. The experimental and simulation results suggest that solvent molecules coordinated the Na insertion mechanisms into the amine interlayer during discharging. These understandings of the Na intercalation mechanism in materials based on Ni0.1VOx NTs would be useful to design more stable and high-performance VOx-based electrodes for Na battery applications. PMID:25562784

Kim, Hyunjin; Kim, Dong Young; Kim, Yongsu; Lee, Seok-Soo; Park, Kwangjin

2015-01-28

119

Interaction of (Na + K + 2 Cl) cotransport and the Na/K pump in cultured chick cardiac myocytes.  

PubMed

We have recently reported the presence of an electroneutral (Na + K + 2 Cl) cotransport mechanism that is bumetanide-sensitive and maintains Cli above its electrochemical equilibrium in cultured chick heart cells. In steady state, (Na + K + 2 Cl) cotransport is inwardly directed and so contributes to the Na influx that must be counterbalanced by the activity of the Na/K pump to maintain Nai homeostasis. We now show that manipulating (Na + K + 2 Cl) cotransport by restoring Clo to a Cl-free solution indirectly influences Na/K pump activity because the bumetanide-sensitive recovery of aiNa to its control level and the accompanying hyperpolarization could be blocked by 10(-4)M ouabain. In another protocol, when the Na/K pump was reactivated by restoring Ko (from 0.5 mM to 5.4 mM) and removing ouabain, the recovery of aNa was attenuated by 10(-4)M bumetanide. The relatively slow rate of ouabain dissociation coupled with the activation of Na influx by (Na + K + 2 Cl) cotransport clearly establishes the interaction of these transport mechanisms in regulating Nai. Although (Na + K + 2 Cl) cotransport is electroneutral, secondary consequences of its activity can indirectly affect the electrophysiological properties of cardiac cells. PMID:2811863

Liu, S; Jacob, R; Piwnica-Worms, D; Lieberman, M

1989-09-01

120

Na(+) channel function, regulation, structure, trafficking and sequestration.  

PubMed

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

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

2015-03-15

121

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

PubMed Central

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 ?(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

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

2012-01-01

122

Formation of Na-containing molecular ions at Io  

NASA Technical Reports Server (NTRS)

Fast sodium atoms, which appear to be associated with the motion of the magnetic 'field lines' downstream from Io (Schneider et al. 1991), are thought to be produced by dissociation of NaX(+) in Io's plasma torus. It was suggested that these molecular ions are formed near Io's exobase by electron-impact ionization and picked up be the corotating filed lines (Wilson and Schneider 1994). Because electron cooling processes dominate electron-impact ionization in Io's corona, two reactions are suggested here as sources of NaX(+) and, hence, as the ultimate sources of the observed fast Na. First, the charge-exchange cross sections for forming NaX(+) are shown to be large for plasma torus ions (O(+), S(+), O(2+), S(3+)) colliding with NaX molecules in Io's corona. Sputtering from the surface (Chrisey et al. 1988) and rapid transport to the exobase is a potential source of NaX, where X is O,S, Na, or a molecular species such as NaS or O2. Second ions of the more abundant molecules (e.g., SO(+), SO2(+), O2(+), and S2(+)) can react efficiently with atomic Na in Io's corona to form NaX(+). Here cross sections are estimated for these two processes, as well as for charge exchange in O(+) and S(+) on Na collisions.

Johnson, R. E.

1994-01-01

123

Na+-pyrophosphatase: a novel primary sodium pump.  

PubMed

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

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

2007-07-31

124

Weekday Blue/Orange Route PAX/hr. PAX/mi. $/Pass. Weekend Blue/Orange Route n/a n/a n/a Weekday Blue/Orange Route  

E-print Network

/a n/a n/a Grounds Loop Weekend Hereford Special 21.03 2.23 $0.96 Central Grounds Shuttle Holiday Blue/Orange Route n/a n/a n/a Weekend Hereford Special Holiday Special 30.07 3.11 $0.69 Holiday Blue/Orange Route 9

Acton, Scott

125

Pair correlations in an NaCl-SPC water model  

NASA Astrophysics Data System (ADS)

The ten pair correlation functions characterizing the equilibrium structure of a simple electrolyte such as NaCl-water and previously obtained for a NaCl-SPC water model within the extended RISM framework are tested against molecular dynamics, constrained dynamics and Monte Carlo simulations employing Ewald and reaction field schemes for a high-temperature, highpressure thermodynamic state where all these approaches become simultaneously feasible. The O-O, H-H, Cl-O, and Na-Na RISM correlations are in good agreement with the simulation data. The Na-O, Na-H, and Na-Cl results agree in phase, but the RISM peaks are too small. Distinct differences in the position of the first peak are observed in the case of the O-H, Cl-H, and Cl-Cl pair correlations. These results provide evidence that the main reason for these discrepancies are the statistical approximations involved in the extended RISM scheme.

Hummer, Gerhard; Soumpasis, Dikeos M.; Neumann, Martin

126

Diffuse sorption modeling: apparent H/Na, or the same, Al/Na exchange on clays.  

PubMed

Clay minerals are specified by permanent negative surface charge. In solutions of sodium salts, the surface of clay is covered by exchangeable sodium ions. In an acidic field (pH<4-6), sodium ions are displaced from the surface. This apparent H/Na exchange is conditioned by dissolution of alumina, followed by Al/Na exchange. Two kinds of published experimental data were considered in order to follow Al/Na exchange: the first is direct measurement of exchangeable sodium and aluminum in clay, and the second is exchange sorption of trace metal. Because of the equivalency of ionic exchange, trace metal acts as a probe, indicating the sodium content in clay. These experimental data were successfully modeled with use of the Poisson-Boltzmann equation, with the assumption that all exchange cations are located in the diffuse layer. PMID:19464695

Pivovarov, Sergey

2009-08-15

127

Difference between hypertonic NaCl and NaHCO3 as osmotic diuretics in dog kidneys.  

PubMed

To compare the osmotic inhibitory effects of NaCl and NaHCO3 on proximal tubular fluid reabsorption, plasma osmolality was raised by 40 mosmol kg-1 H2O by infusing hypertonic NaCl and NaHCO3 in volume-expanded dogs receiving ethacrynic acid. In five dogs studied at constant plasma pH 7.5, both NaCl and NaHCO3 reduced water reabsorption by 29 +/- 2%. However, NaCl infusion reduced bicarbonate reabsorption by 31 +/- 2%, whereas bicarbonate reabsorption remained unchanged during NaHCO3 infusion. In six dogs, bicarbonate reabsorption was kept constant during NaCl and NaHCO3 infusion by adjustments of plasma pH. At similar glomerular filtration rates (42.4 +/- 2.9 ml min-1), water reabsorption was 28.7 +/- 1.7 ml min-1 in the control period, 29.4 +/- 2.5 ml min-1 during hypertonic NaCl infusion and 20.6 +/- 1.2 ml min-1 during hypertonic NaHCO3 infusion. Therefore, NaCl did not reduce proximal tubular water reabsorption by a direct osmotic effect. By calculating the regression coefficient for the relationship between measured chloride reabsorption and maximal convective chloride flux, the effective reflection coefficient for NaCl averaged 0.11 +/- 0.01. The combination of a low reflection coefficient and high permeability may explain why hypertonic NaCl is not an osmotic diuretic. PMID:2618758

Ostensen, J; Stokke, E S; Bugge, J F; Langberg, H; Kiil, F

1989-10-01

128

Gas-exposure enhanced Na* emission from Na-rich surfaces  

NASA Technical Reports Server (NTRS)

The optical emission attributed to electronically desorbed excited sodium atoms from NaCl and Na-evaporated surfaces is shown to be enhanced by exposure of the surface to gaseous CO2 and N2. This is the first observation of enhancement of electron-simulated desorption of substrate atoms caused by the exposure of surfaces to gaseous molecules which do not contain the desorbed atoms. The large amount of excited-sodium yield at 60 K provides evidence for nonexistence of the secondary-electron excitation of thermally desorbed ground sodium.

Xu, Jun; Albridge, Royal; Barnes, Alan; Yang, Xinxing; Tolk, Norman

1992-01-01

129

Diseo y evaluacin de un programa de seguimiento farmacoteraputico a pacientes anticoagulados en atencin primaria de salud  

Microsoft Academic Search

Resumen La incorporacin del farmacutico a los equipos de atencin primaria en Galicia supone la implementacin y desarrollo de programas de seguimiento farmacoteraputico. El objetivo principal de este estudio fue dise- ar y evaluar un programa de seguimiento farmacoteraputico a pacientes anticoagulados; otros objetivos secundarios fueron los siguientes: 1. Establecer y cuantificar indicadores de seguimiento. 2. Registrar, cuantificar y clasificar

MM Guerra Garca

130

[Effects of NaCl stress on the seedling growth and K(+)- and Na(+) -allocation of four leguminous tree species].  

PubMed

Taking the pot-cultured seedlings of four leguminous tree species (Albizia julibrissin, Robinia pseudoacacia, Sophora japonica, and Gleditsia sinensis) as test materials, this paper studied their growth indices, critical salt concentration (C50), and K+ and Na+ allocation under different levels of NaCl stress, aimed to understand the difference of test tree species in salt tolerance. NaCl stress inhibited the seedling growth of the tree species. Under NaCl stress, the dry matter accumulation decreased, while the root/shoot ratio increased, especially for A. julibrissin and G. sinensis. Quadratic regression analysis showed that the C50 of A. julibrissin, R. pseudoacacia, S. japonica, and G. sinensis was 3.0 per thousand, 5.0 per thousand, 4.5 per thousand, and 3.9 per thousand, respectively, i.e., the salt tolerance of the four tree species was in the order of R. pseudoacacia > S. japonica > G. sinensis > A. julibrissin. In the root, stem, and leaf of the four tree species seedlings, the Na+ content increased with the increase of NaCl stress, while the K+ content (except in the root of A. julibrissin) decreased after an initial increase, resulting in a larger difference in the K+/Na+ ratio in the organs. Under the same NaCl stress, the allocation of Na+ in different organs of the four tree species seedlings decreased in the order of root>stem>leaf, while that of K+ differed with tree species and NaCl stress, and leaf was the main storage organ for K+. The K+/Na+ ratio in different organs decreased in the sequence of leaf>stem>root. R. pseudoacacia under NaCl stress accumulated more K+ and less Na+ in stem and leaf, and had higher K+/Na+ ratio in all organs and higher dry mass, being assessed to be more salt-tolerant. In contrast, A. julibrissin under high NaCl stress accumulated more Na+ in stem and leaf, and had a lower K+/Na+ ratio in all organs and lower dry mass, being evaluated to be lesser salt-tolerant. The K+ accumulation in seedling stem and leaf and the Na+ retention in seedling root could be the main reasons for the salt tolerance of leguminous tree species under NaCl stress. PMID:21812288

Mo, Hai-Bo; Yin, Yun-Long; Lu, Zhi-Guo; Wei, Xiu-Jun; Xu, Jian-Hua

2011-05-01

131

Characterization of NaV1.6-mediated Na+ currents in smooth muscle cells isolated from mouse vas deferens.  

PubMed

Patch-clamp experiments were performed to investigate the behavior of voltage-activated inward currents in vas deferens myocytes from Na(V)1.6-null mice (Na(V)1.6(-/-)) lacking the expression of the Na(+) channel gene, Scn8a, and their wild-type littermates (Na(V)1.6(+/+)). Immunohistochemistry confirmed expression of Na(V)1.6 in the muscle of Na(V)1.6(+/+), but not Na(V)1.6(-/-), vas deferens. PCR analysis revealed that the only beta(1)-subunit gene expressed in Na(V)1.6(+/+) vas deferens was Scn1b. In Na(V)1.6(+/+) myocytes, the threshold for membrane currents evoked by 20 msec voltage ramps (-100 mV to 60 mV) was -38.5 +/- 4.6 mV and this was shifted to a more positive potential (-31.2 +/- 4.9 mV) by tetrodotoxin (TTX). In Na(V)1.6(-/-) myocytes, the threshold was -30.4 +/- 3.4 mV and there was no TTX-sensitive current. The Na(+) current (I(Na)) in Na(V)1.6(+/+) myocytes had a bell-shaped current-voltage relationship that peaked at approximately -10 mV. Increasing the duration of the voltage ramps beyond 20 msec reduced the peak amplitude of I(Na). I(Na) displayed both fast (tau approximately 10 msec) and slow (tau approximately 1 sec) recovery from inactivation, the magnitude of the slow component increasing with the duration of the conditioning pulse (5-40 msec). During repetitive activation (5-40 msec pulses), I(Na) declined at stimulation frequencies > 0.5 Hz and at 10 Hz Na) is due solely to Na(V)1.6 in Na(V)1.6(+/+) myocytes. The gating properties of these channels suggest they play a major role in regulating smooth muscle excitability, particularly in response to rapid depolarizing stimuli. PMID:20054822

Zhu, Hai-Lei; Shibata, Atsushi; Inai, Tetsuichiro; Nomura, Masatoshi; Shibata, Yosaburo; Brock, James A; Teramoto, Noriyoshi

2010-04-01

132

Hydrogen Sulfide Induced Disruption of Na+ Homeostasis in the Cortex  

PubMed Central

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

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

2012-01-01

133

Um novo paradigma na medicina DESENVOLVEU UMA METODOLOGIA DISRUPTIVA BASEADA NA INTEGRAO DE AVANADAS TECNOLOGIAS  

E-print Network

INTEGRAO DE AVANADAS TECNOLOGIAS DE GENTICA E MTODOS COMPUTACIONAIS SOFISTICADOS. OBJECTIVO? AJUDAR OS MDICOS A MELHORAR DIAGNSTICOS NA MEDICINA DO CORAO. #12;Depois do aperfeioamento das tecnologias pa cardacas. A tecnologia permite analisar um elevado nme- ro de alteraes genticas em simultneo, de for

Instituto de Sistemas e Robotica

134

Na+ transport in the normal and failing heart remember the balance  

PubMed Central

In the heart, intracellular Na+ concentration ([Na+]i) is a key modulator of Ca2+ cycling, contractility and cardiac myocyte metabolism. Several Na+ transporters are electrogenic, thus they both contribute to shaping the cardiac action potential and at the same time are affected by it. [Na+]i is controlled by the balance between Na+ influx through various pathways, including the Na+/Ca2+ exchanger and Na+ channels, and Na+ extrusion via the Na+/K+-ATPase. [Na+]i is elevated in HF due to a combination of increased entry through Na+ channels and/or Na+/H+ exchanger and reduced activity of the Na+/K+-ATPase. Here we review the major Na+ transport pathways in cardiac myocytes and how they participate in regulating [Na+]i in normal and failing hearts. PMID:23608603

Despa, Sanda; Bers, Donald M.

2013-01-01

135

Structural Fold and Binding Sites of the Human Na+-Phosphate Cotransporter NaPi-II  

PubMed Central

Phosphate plays essential biological roles and its plasma level in humans requires tight control to avoid bone loss (insufficiency) or vascular calcification (excess). Intestinal absorption and renal reabsorption of phosphate are mediated by members of the SLC34 family of sodium-coupled transporters (NaPi-IIa,b,c) whose membrane expression is regulated by various hormones, circulating proteins, and phosphate itself. Consequently, NaPi-II proteins are also potentially important pharmaceutical targets for controlling phosphate levels. Their crucial role in Pi homeostasis is underscored by pathologies resulting from naturally occurring SLC34 mutations and SLC34 knockout animals. SLC34 isoforms have been extensively studied with respect to transport mechanism and structure-function relationships; however, the three-dimensional structure is unknown. All SLC34 transporters share a duplicated motif comprising a glutamine followed by a stretch of threonine or serine residues, suggesting the presence of structural repeats as found in other transporter families. Nevertheless, standard bioinformatic approaches fail to clearly identify a suitable template for molecular modeling. Here, we used hydrophobicity profiles and hidden Markov models to define a structural repeat common to all SLC34 isoforms. Similar approaches identify a relationship with the core regions in a crystal structure of Vibrio cholerae Na+-dicarboxylate transporter VcINDY, from which we generated a homology model of human NaPi-IIa. The aforementioned SLC34 motifs in each repeat localize to the center of the model, and were predicted to form Na+ and Pi coordination sites. Functional relevance of key amino acids was confirmed by biochemical and electrophysiological analysis of expressed, mutated transporters. Moreover, the validity of the predicted architecture is corroborated by extensive published structure-function studies. The model provides key information for elucidating the transport mechanism and predicts candidate substrate binding sites. PMID:24655502

Fenollar-Ferrer, Cristina; Patti, Monica; Knpfel, Thomas; Werner, Andreas; Forster, IanC.; Forrest, LucyR.

2014-01-01

136

Regulation of persistent Na current by interactions between beta subunits of voltage-gated Na channels.  

PubMed

The beta subunits of voltage-gated Na channels (Scnxb) regulate the gating of pore-forming alpha subunits, as well as their trafficking and localization. In heterologous expression systems, beta1, beta2, and beta3 subunits influence inactivation and persistent current in different ways. To test how the beta4 protein regulates Na channel gating, we transfected beta4 into HEK (human embryonic kidney) cells stably expressing Na(V)1.1. Unlike a free peptide with a sequence from the beta4 cytoplasmic domain, the full-length beta4 protein did not block open channels. Instead, beta4 expression favored open states by shifting activation curves negative, decreasing the slope of the inactivation curve, and increasing the percentage of noninactivating current. Consequently, persistent current tripled in amplitude. Expression of beta1 or chimeric subunits including the beta1 extracellular domain, however, favored inactivation. Coexpressing Na(V)1.1 and beta4 with beta1 produced tiny persistent currents, indicating that beta1 overcomes the effects of beta4 in heterotrimeric channels. In contrast, beta1(C121W), which contains an extracellular epilepsy-associated mutation, did not counteract the destabilization of inactivation by beta4 and also required unusually large depolarizations for channel opening. In cultured hippocampal neurons transfected with beta4, persistent current was slightly but significantly increased. Moreover, in beta4-expressing neurons from Scn1b and Scn1b/Scn2b null mice, entry into inactivated states was slowed. These data suggest that beta1 and beta4 have antagonistic roles, the former favoring inactivation, and the latter favoring activation. Because increased Na channel availability may facilitate action potential firing, these results suggest a mechanism for seizure susceptibility of both mice and humans with disrupted beta1 subunits. PMID:19228957

Aman, Teresa K; Grieco-Calub, Tina M; Chen, Chunling; Rusconi, Raffaella; Slat, Emily A; Isom, Lori L; Raman, Indira M

2009-02-18

137

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

PubMed

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

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

2014-08-01

138

Ionic liquid electrolytes with various sodium solutes for rechargeable Na/NaFePO4 batteries operated at elevated temperatures.  

PubMed

NaFePO4 with an olivine structure is synthesized via chemical delithiation of LiFePO4 followed by electrochemical sodiation of FePO4. Butylmethylpyrrolidinium-bis(trifluoromethanesulfonyl)imide (BMP-TFSI) ionic liquid (IL) with various sodium solutes, namely NaBF4, NaClO4, NaPF6, and NaN(CN)2, is used as an electrolyte for rechargeable Na/NaFePO4 cells. The IL electrolytes show high thermal stability (>350 C) and nonflammability, and are thus ideal for high-safety applications. The highest conductivity and the lowest viscosity of the electrolyte are obtained with NaBF4. At an elevated temperature (above 50 C), the IL electrolyte is more suitable than a conventional organic electrolyte for the sodium cell. At 75 C, the measured capacity of NaFePO4 in a NaBF4-incorporated IL electrolyte is as high as 152 mAh g(-1) (at 0.05 C), which is near the theoretical value (154 mAh g(-1)). Moreover, 60% of this capacity can be retained when the charge-discharge rate is increased to 1 C. PMID:25295391

Wongittharom, Nithinai; Wang, Chueh-Han; Wang, Yi-Chen; Yang, Cheng-Hsien; Chang, Jeng-Kuei

2014-10-22

139

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

PubMed Central

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

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

2014-01-01

140

NA Nonlinear Equation-of-state Inversion  

NASA Astrophysics Data System (ADS)

A fully non-linear inversion scheme is introduced for the determination of the parameters controlling the equation-of-state and elasticity of mineral phases using the thermodynamically consistent finite-strain formulation introduced by Stixrude & Lithgow-Bertelloni (2005). This inversion exploits a directed search in an eight-dimensional parameter space using the Neighbourhood Algorithm (NA) of Sambridge (1999) to search for the minimum of an objective function representing the misfit to multiple data sets that constrain different aspects of the mineral behaviour. No derivatives are employed and the progress towards the minimum builds on the accumulated information on the character of the parameter space acquired as the inversion progresses. When only a limited range of experimental information is available there is a strong possibility of multiple minima in the objective function, which can pose problems for conventional iterative least-squares or other gradient methods. The addition of many different styles of data tends to produce a better defined minimum. The influence of different data types can be readily assessed by allowing differential weighting. The new procedure is illustrated by application to MgO, for which extensive experimental data are available. These include the variation of relative volume V with temperature T and pressure P from both static and shock-compression experiments, acoustic measurements of compressional and shear (and hence bulk) moduli, and calorimetric determinations of entropy as a function of temperature at atmospheric pressure. Preliminary NA modeling highlighted tensions between marginally incompatible subsets of data. We therefore excluded one-atmosphere V(T) data for T ? 1800 K for which the quasi-harmonic approximation is inadequate (Wu et al., 2008) along with elastic moduli derived from Brillouin spectroscopy under conditions (P ? 14 GPa) where significant departures from hydrostatic conditions are expected. With these limited exclusions based on sound physical principles, the NA search identified a compact family of models that provide an excellent fit to the diverse experimental data and a measure of the covariance between key model parameters.

Jackson, I.; Kennett, B. L.

2008-12-01

141

Magnesium correction to the NaKCa chemical geothermometer  

USGS Publications Warehouse

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

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

1979-01-01

142

Interactions of Local Anesthetics with Voltage-gated Na + Channels  

Microsoft Academic Search

Voltage-gated Na+ channels are dynamic transmembrane proteins responsible for the rising phase of the action potential in excitable membranes. Local anesthetics (LAs) and structurally related antiarrhythmic and anticonvulsant compounds target specific sites in voltage-gated Na+ channels to block Na+ currents, thus reducing excitability in neuronal, cardiac, or central nervous tissue. A high-affinity LA block is produced by binding to open

C. Nau; G. K. Wang

2004-01-01

143

Simulation of Na D emission near Europa during eclipse  

USGS Publications Warehouse

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.

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

2008-01-01

144

Sodium superionic conduction in Na2B12H12.  

PubMed

Impedance measurements indicate that Na2B12H12 exhibits dramatic Na(+) conductivity (on the order of 0.1 S cm(-1)) above its order-disorder phase-transition at ?529 K, rivaling that of current, solid-state, ceramic-based, Na-battery electrolytes. Superionicity may be aided by the large size, quasispherical shape, and high rotational mobility of the B12H12(2-) anions. PMID:24584582

Udovic, Terrence J; Matsuo, Motoaki; Unemoto, Atsushi; Verdal, Nina; Stavila, Vitalie; Skripov, Alexander V; Rush, John J; Takamura, Hitoshi; Orimo, Shin-ichi

2014-04-11

145

Metastable surface phase for Na xC 60  

NASA Astrophysics Data System (ADS)

Na xC 60 thin films with Na concentration 0 ? x ? 3 were investigated using angle-dependent photoelectron spectroscopy. For low doping we observed two distinct fulleride phases coexisting with regions of pristine C 60. One of these fulleride phase is predominantly formed close to the surface and disappears after annealing and further addition of Na. At higher doping a phase with stoichiometry of x = 3 is formed.

Schiessling, J.; Marenne, I.; Kjeldgaard, L.; Rudolf, P.

2007-09-01

146

CaMKII-dependent regulation of cardiac Na+ homeostasis  

PubMed Central

Na+ homeostasis is a key regulator of cardiac excitation and contraction. The cardiac voltage-gated Na+ channel, NaV1.5, critically controls cell excitability, and altered channel gating has been implicated in both inherited and acquired arrhythmias. Ca2+/calmodulin-dependent protein kinase II (CaMKII), a serine/threonine kinase important in cardiac physiology and disease, phosphorylates NaV1.5 at multiple sites within the first intracellular linker loop to regulate channel gating. Although CaMKII sites on the channel have been identified (S516, T594, S571), the relative role of each of these phospho-sites in channel gating properties remains unclear, whereby both loss-of-function (reduced availability) and gain-of-function (late Na+ current, INaL) effects have been reported. Our review highlights investigating the complex multi-site phospho-regulation of NaV1.5 gating is crucial to understanding the genesis of acquired arrhythmias in heart failure (HF) and CaMKII activated conditions. In addition, the increased Na+ influx accompanying INaL may also indirectly contribute to arrhythmia by promoting Ca2+ overload. While the precise mechanisms of Na+ loading during HF remain unclear, and quantitative analyses of the contribution of INaL are lacking, disrupted Na+ homeostasis is a consistent feature of HF. Computational and experimental observations suggest that both increased diastolic Na+ influx and action potential prolongation due to systolic INaL contribute to disruption of Ca2+ handling in failing hearts. Furthermore, simulations reveal a synergistic interaction between perturbed Na+ fluxes and CaMKII, and confirm recent experimental findings of an arrhythmogenic feedback loop, whereby CaMKII activation is at once a cause and a consequence of Na+ loading. PMID:24653702

Grandi, Eleonora; Herren, Anthony W.

2014-01-01

147

Synthesis of NaA zeolite membrane by microwave heating  

Microsoft Academic Search

The synthesis of NaA zeolite membrane on a porous ?-Al2O3 support by microwave heating (MH) was investigated. The formation of a NaA zeolite membrane was drastically promoted by MH. The synthesis time was reduced from 3 h for conventional heating (CH) to 15 min for MH. Surface seeding cannot only promote the formation of NaA zeolite on the support, but

Xiaochun Xu; Weishen Yang; Jie Liu; Liwu Lin

2001-01-01

148

The trafficking of Na(V)1.8.  

PubMed

The ?-subunit of tetrodotoxin-resistant voltage-gated sodium channel Na(V)1.8 is selectively expressed in sensory neurons. It has been reported that Na(V)1.8 is involved in the transmission of nociceptive information from sensory neurons to the central nervous system in nociceptive [1] and neuropathic [24] pain conditions. Thus Na(V)1.8 has been a promising target to treat chronic pain. Here we discuss the recent advances in the study of trafficking mechanism of Na(V)1.8. These pieces of information are particularly important as such trafficking machinery could be new targets for painkillers. PMID:20816723

Swanwick, Richard S; Prister, Alessandro; Okuse, Kenji

2010-12-10

149

The trafficking of NaV1.8  

PubMed Central

The ?-subunit of tetrodotoxin-resistant voltage-gated sodium channel NaV1.8 is selectively expressed in sensory neurons. It has been reported that NaV1.8 is involved in the transmission of nociceptive information from sensory neurons to the central nervous system in nociceptive [1] and neuropathic [24] pain conditions. Thus NaV1.8 has been a promising target to treat chronic pain. Here we discuss the recent advances in the study of trafficking mechanism of NaV1.8. These pieces of information are particularly important as such trafficking machinery could be new targets for painkillers. PMID:20816723

Swanwick, Richard S.; Prister, Alessandro; Okuse, Kenji

2010-01-01

150

Integrated Control of Na Transport along the Nephron.  

PubMed

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

Palmer, Lawrence G; Schnermann, Jrgen

2015-04-01

151

Pion and kaon freezeout in NA44  

SciTech Connect

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

NA44 Collaboration

1994-12-01

152

New results from the NA57 experiment  

NASA Astrophysics Data System (ADS)

The production of hyperons in Pb-Pb and p-Be interaction at 40 A GeV/c beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 A GeV/c are presented for the first time and compared to those measured at 158 A GeV/c. The transverse mass spectra of high statistics, high purity samples of K0S, Lgr, Xgr and OHgr particles produced in Pb-Pb collisions at 158 A GeV/c have been studied in the framework of the blast-wave model. The dependence of the freeze-out parameters on particle species and event centrality is discussed.

Bruno, G. E.; NA57 Collaboration

2004-08-01

153

Lakota na Dakota Wowapi Oti Kin  

NSDL National Science Digital Library

The Lakota na Dakota Wowapi Oti Kin is a one-stop information portal containing Internet resources on people of Lakota and Dakota descent (also known as Sioux or Siouan peoples). Created and maintained by Professor Martin Brokenleg of Augustana College and Dr. Raymond Bucko, S.J. of Creighton University, this site offers Web links in various categories including art and artists / music and musicians, bibliographic resources, demography, education, history, language resources, legal issues, maps, museums, and a host of other Lakota-related sites. For those interested in locating information in the field of Native American studies, specifically on the Sioux peoples, this site is an excellent place to begin your search.

154

Questes mais freqentes na rea de astronomia  

NASA Astrophysics Data System (ADS)

amplamente reconhecido que as pessoas em geral tm grande fascnio e interesse pela Astronomia. Por outro lado, o contedo dessa rea includo no ensino formal est longe de ser abrangente e suficiente para suprir a demanda. Esse interesse permite otimizar a divulgao e o ensino no formal de Astronomia aliando a adequao do contedo expectativa das pessoas. Nesse intuito, nosso trabalho busca mapear que assuntos da Astronomia despertam mais a ateno e o interesse das pessoas e o quanto disso estimulado pela mdia, que freqentemente aproveita-se desse interesse de forma sensacionalista, trazendo contribuies positivas e negativas. Para esta avaliao, utilizamos as pesquisas especficas e de caracterizao do pblico que freqentou o MAst nos anos de 2001 a 2003, pesquisa das matrias de Astronomia veiculadas na mdia escrita da cidade do Rio de Janeiro no mesmo perodo, alm da base de dados do programa Pergunte a um astrnomo, realizado no Observatrio Nacional nos anos de 1997 a 1999. Para a anlise dos dados, dividimos as perguntas em dez categorias, cada uma com suas subcategorias, tomando como referncia as divises, comisses e grupos de trabalho da IAU. Apresentamos neste trabalho os resultados dessa pesquisa, que incluem, entre outros, a predominncia de questes nas categorias Observao do Cu e Sistemas Planetrios enquanto nos jornais dominam as notcias de Sistemas Planetrios e Espao & Astronutica. Outro resultado interessante indicou que as dvidas de crianas do ensino fundamental se concentram em algumas categorias enquanto as questes de adultos so mais distribudas por todas as categorias. Os resultados dessa pesquisa sero aplicados diretamente no aperfeioamento das atividades do Programa de Observao de Cu, bem como na elaborao de novos projetos e eventos realizados no MAst.

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

2003-08-01

155

Mercury's Na Exosphere from MESSENGER Data  

NASA Technical Reports Server (NTRS)

MESSENGER entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UWS) channel of MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS) has been observing Mercury's exosphere nearly continuously. Daily measurements of Na brightness were fitted with non-uniform exospheric models. With Monte Carlo sampling we traced the trajectories of a representative number of test particles, generally one million per run per source process, until photoionization, escape from the gravitational well, or permanent sticking at the surface removed the atom from the simulation. Atoms were assumed to partially thermally accommodate on each encounter with the surface with accommodation coefficient 0.25. Runs for different assumed source processes are run separately, scaled and co-added. Once these model results were saved onto a 3D grid, we ran lines of sight from the MESSENGER spacecraft :0 infinity using the SPICE kernels and we computed brightness integrals. Note that only particles that contribute to the measurement can be constrained with our method. Atoms and molecules produced on the nightside must escape the shadow in order to scatter light if the excitation process is resonant-light scattering, as assumed here. The aggregate distribution of Na atoms fits a 1200 K gas, with a PSD distribution, along with a hotter component. Our models constrain the hot component, assumed to be impact vaporization, to be emitted with a 2500 K Maxwellian. Most orbits show a dawnside enhancement in the hot component broadly spread over the leading hemisphere. However, on some dates there is no dawn/dusk asymmetry. The portion of the hot/cold source appears to be highly variable.

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

2012-01-01

156

Na/sup +/-H/sup +/ exchange and Na/sup +/-dependent transport systems in streptozotocin diabetic rat kidneys  

SciTech Connect

The streptozotocin-induced diabetic rat was used to test the hypothesis that Na/sup +/-H/sup +/ exchange activity in the proximal tubule luminal membrane would be increased in association with renal hypertrophy, altered glomerular hemodynamics, enhanced filtered load and tubular reabsorption of /sup 22/Na/sup +/, and stimulated /sup 22/Na= pump activity in the basolateral membrane, previously reported characteristics of this experimental animal model. Amiloride-sensitive H/sup +/ gradient-dependent Na/sup +/ uptake and Na/sup +/ gradient-dependent H/sup +/ flux were increased in brush-border membrane vesicles from the streptozotocin-treated animals. Na/sup +/ gradient-dependent uptakes of phosphate, D-glucose, L-proline, and myoinositol were decreased in the drug-induced diabetic animals. These membrane transport alterations were not found when the streptozotocin-diabetic animals were treated with insulin.

El-Seifi, S.; Freiberg, J.M.; Kinsella, F.J.; Cheng, L.; Sacktor, B.

1987-01-01

157

Mechanism of ?-Conotoxin PIIIA Binding to the Voltage-Gated Na+ Channel NaV1.4  

PubMed Central

Several subtypes of voltage-gated Na+ (NaV) channels are important targets for pain management. ?-Conotoxins isolated from venoms of cone snails are potent and specific blockers of different NaV channel isoforms. The inhibitory effect of ?-conotoxins on NaV channels has been examined extensively, but the mechanism of toxin specificity has not been understood in detail. Here the known structure of ?-conotoxin PIIIA and a model of the skeletal muscle channel NaV1.4 are used to elucidate elements that contribute to the structural basis of ?-conotoxin binding and specificity. The model of NaV1.4 is constructed based on the crystal structure of the bacterial NaV channel, NaVAb. Six different binding modes, in which the side chain of each of the basic residues carried by the toxin protrudes into the selectivity filter of NaV1.4, are examined in atomic detail using molecular dynamics simulations with explicit solvent. The dissociation constants (Kd) computed for two selected binding modes in which Lys9 or Arg14 from the toxin protrudes into the filter of the channel are within 2 fold; both values in close proximity to those determined from dose response data for the block of NaV currents. To explore the mechanism of PIIIA specificity, a double mutant of NaV1.4 mimicking NaV channels resistant to ?-conotoxins and tetrodotoxin is constructed and the binding of PIIIA to this mutant channel examined. The double mutation causes the affinity of PIIIA to reduce by two orders of magnitude. PMID:24676211

Chen, Rong; Robinson, Anna; Chung, Shin-Ho

2014-01-01

158

Effect of NaCl on nitrogen fixation of unadapted and NaCl-adapted Azolla pinnataAnabaena azollae  

Microsoft Academic Search

Exposure of Azolla pinnataAnabaena azollae to NaCl induced a sharp decline in nitrogenase activity. A lethal dose of NaCl (40mM) for the growth of A. pinnataA. azollae complex could inhibit the nitrogenase activity by 39%, revealing for higher sensitivity of general growth to NaCl than the nitrogenase activity. Salinity caused a distinct shift in the profile of heterocyst differentiation in

Vandna Rai; S. P. Tiwari; Ashwani K. Rai

2001-01-01

159

Fases lquido-cristalinas anisotrpicas Fases lamelares preparao de lipossomas por  

E-print Network

#12;Mesofases em solventes orgânicos CTAB em (a) ­ água, (b) ­ glicerol, (c) ­ formamida, (d Uninvestigated area I DecanolC16 TAPA6000 Water II- nor hex, III- lam, IV ­ L2, V ­ inv hex, VI ­ inv rods II- nor hex, III- lam, IV ­ L2, V ­ inv rods I ­ nor hex, II ­lam III ­ L2 CTA+ + água + decanol : efeito

Loh, Watson

160

Estimating the hydrogen ion concentration in concentrated NaCl and Na{sub 2}SO{sub 4} electrolytes  

SciTech Connect

Combination glass electrodes were tested for determining H{sup +} concentrations in concentrated pure and mixed NaCl and Na{sub 2}SO{sub 4} solutions, as well as natural brine systems. NaCl, Na{sub 2}SO{sub 4}, and mixtures of NaCl and Na{sub 2}SO{sub 4} solutions were analyzed. Correction factors for estimating pC{sub H}{sup +} (negative logarithm of H{sup +} concentration) were determined from measured/observed pH values. Required Gran-type titrations were done with HCl and/or NaOH. The titration method is described and a step-by-step procedure provided; it has been used previously for determining pC{sub H}{sup +} values of synthetic chloride-dominated brines. Precautions are required to determine correction factors for electrolytes that react with H{sup +} or OH{sup {minus}} [sulfate brines for titration with acid; magnesium brines for titration with base because of precipitation of Mg(OH)2]. Correction factors A (pC{sub H}{sup +} = pH{sub ob} + A) from HCl titrations were similar to those from NaOH titrations where the concentration of free H{sup +} was calculated using a thermodynamic model. These values should be applicable to solns with a very large range in measured pH values (2 to 12). Because a large number of solns were titrated with HCl and the A values are similar for HCl and NaOH titrations, the A values for NaCl and Na2SO4 solns were fit as a function of molality to allow extrapolation. For NaCl solns 0 to 6.0 M, A can be obtained by multiplying the molality by 0.159. For Na2SO4 solns 0 to 2.0 M, the values of A can be obtained from (0.221 {minus} 0.549X + 0.201X{sup 2}), where X is the molality of Na{sub 2}SO{sub 4}. Orion-Ross electrode evaluations indicated that the A values did not differ significantly for different electrodes. Results suggest that the data in this report can be used to estimate A values for different NaCl and Na{sub 2}SO{sub 4} solns even for noncalibrated electrodes.

Rai, D.; Felmy, A.R.; Juracich, S.P.; Rao, F. [Pacific Northwest Lab., Richland, WA (United States)

1995-06-01

161

Relation of membrane vesicles to volume control and Na+-transport in smooth muscle: studies on Na+-rich tissues.  

PubMed

Correlation between operation of a volume control system (independent of Na+-K+ -ATPase) and membrane vesicle structure was examined in strips of rat myometrium made Na-rich by incubation in Krebs-Ringer solutions at 5 degrees C. Some pieces of tissue were analyzed for Na+, K+, ATP and water contents before and after rewarming to 37 degrees C. Other pieces of tissue were prepared and examined in the electron microscope. The membrane vesicles along the surface of the muscle cells were reduced from the numberin fresh tissues made Na+-rich by overnight incubation in K+-free Ringer solution at 5 degrees C. Rewarming of Na+-rich tissues under conditions thought to inhibit Na+-K+-ATPase caused the loss of Na+ with water and with utake of K+ but the vesicles did not increase in number. Na+-K+ATPase activity was suggested to inhibit vesicle formation by competing for ATP. The loss of water and increase in vesicle number was Ca2+-dependent but did not require Na+. Inhibition of the volume control system by iodoacetamide, Ca2+-free solution and other procedures resulted in swelling of membrane vesicles. The membrane vesicles were suggested to be sites of a mechanochemical system of volume control and the mechanochemical step was suggested to involve discharge of membrane vesicles. PMID:157384

Garfield, R E; Daniel, E E

1977-06-01

162

Kinetics and stoichiometry of coupled Na efflux and Ca influx (Na\\/Ca exchange) in barnacle muscle cells  

Microsoft Academic Search

ABSTRACT,Coupled,Na exit\\/Ca 2+ entry (Na\\/Ca exchange,operating,in the Ca 2+ influx mode),was studied,in giant barnacle,muscle,cells by measuring,~Na + efflux and 4~Ca2+ influx in internally perfused, ATP-fueled cells in which the Na + pump was poisoned by 0.1 mM ouabain. Internal free Ca ~+, [Ca ~+ ]i, was controlled with a Ca-EGTA buffering,system,containing,8 mM,EGTA and,varying,amounts,of Ca ~+. Ca ~+ sequestration,in internal

HECTOR RASGADO-FLORES; ELIGIO M. SANTIAGO; MORDECAI P. BLAUSTEIN

1989-01-01

163

Kinetics and stoichiometry of coupled Na efflux and Ca influx (Na/Ca exchange) in barnacle muscle cells  

PubMed Central

Coupled Na+ exit/Ca2+ entry (Na/Ca exchange operating in the Ca2+ influx mode) was studied in giant barnacle muscle cells by measuring 22Na+ efflux and 45Ca2+ influx in internally perfused, ATP-fueled cells in which the Na+ pump was poisoned by 0.1 mM ouabain. Internal free Ca2+, [Ca2+]i, was controlled with a Ca-EGTA buffering system containing 8 mM EGTA and varying amounts of Ca2+. Ca2+ sequestration in internal stores was inhibited with caffeine and a mitochondrial uncoupler (FCCP). To maximize conditions for Ca2+ influx mode Na/Ca exchange, and to eliminate tracer Na/Na exchange, all of the external Na+ in the standard Na+ sea water (NaSW) was replaced by Tris or Li+ (Tris-SW or LiSW, respectively). In both Na-free solutions an external Ca2+ (Cao)-dependent Na+ efflux was observed when [Ca2+]i was increased above 10(-8) M; this efflux was half-maximally activated by [Ca2+]i = 0.3 microM (LiSW) to 0.7 microM (Tris-SW). The Cao-dependent Na+ efflux was half-maximally activated by [Ca2+]o = 2.0 mM in LiSW and 7.2 mM in Tris-SW; at saturating [Ca2+]o, [Ca2+]i, and [Na+]i the maximal (calculated) Cao-dependent Na+ efflux was approximately 75 pmol#cm2.s. This efflux was inhibited by external Na+ and La3+ with IC50's of approximately 125 and 0.4 mM, respectively. A Nai-dependent Ca2+ influx was also observed in Tris-SW. This Ca2+ influx also required [Ca2+]i greater than 10(-8) M. Internal Ca2+ activated a Nai-independent Ca2+ influx from LiSW (tracer Ca/Ca exchange), but in Tris-SW virtually all of the Cai-activated Ca2+ influx was Nai-dependent (Na/Ca exchange). Half-maximal activation was observed with [Na+]i = 30 mM. The fact that internal Ca2+ activates both a Cao-dependent Na+ efflux and a Nai- dependent Ca2+ influx in Tris-SW implies that these two fluxes are coupled; the activating (intracellular) Ca2+ does not appear to be transported by the exchanger. The maximal (calculated) Nai-dependent Ca2+ influx was -25 pmol/cm2.s. At various [Na+]i between 6 and 106 mM, the ratio of the Cao-dependent Na+ efflux to the Nai-dependent Ca2+ influx was 2.8-3.2:1 (mean = 3.1:1); this directly demonstrates that the stoichiometry (coupling ratio) of the Na/Ca exchange is 3:1. These observations on the coupling ratio and kinetics of the Na/Ca exchanger imply that in resting cells the exchanger turns over at a low rate because of the low [Ca2+]i; much of the Ca2+ extrusion at rest (approximately 1 pmol/cm2.s) is thus mediated by an ATP-driven Ca2+ pump.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2769225

1989-01-01

164

Kinetics and stoichiometry of coupled Na efflux and Ca influx (Na/Ca exchange) in barnacle muscle cells.  

PubMed

Coupled Na+ exit/Ca2+ entry (Na/Ca exchange operating in the Ca2+ influx mode) was studied in giant barnacle muscle cells by measuring 22Na+ efflux and 45Ca2+ influx in internally perfused, ATP-fueled cells in which the Na+ pump was poisoned by 0.1 mM ouabain. Internal free Ca2+, [Ca2+]i, was controlled with a Ca-EGTA buffering system containing 8 mM EGTA and varying amounts of Ca2+. Ca2+ sequestration in internal stores was inhibited with caffeine and a mitochondrial uncoupler (FCCP). To maximize conditions for Ca2+ influx mode Na/Ca exchange, and to eliminate tracer Na/Na exchange, all of the external Na+ in the standard Na+ sea water (NaSW) was replaced by Tris or Li+ (Tris-SW or LiSW, respectively). In both Na-free solutions an external Ca2+ (Cao)-dependent Na+ efflux was observed when [Ca2+]i was increased above 10(-8) M; this efflux was half-maximally activated by [Ca2+]i = 0.3 microM (LiSW) to 0.7 microM (Tris-SW). The Cao-dependent Na+ efflux was half-maximally activated by [Ca2+]o = 2.0 mM in LiSW and 7.2 mM in Tris-SW; at saturating [Ca2+]o, [Ca2+]i, and [Na+]i the maximal (calculated) Cao-dependent Na+ efflux was approximately 75 pmol#cm2.s. This efflux was inhibited by external Na+ and La3+ with IC50's of approximately 125 and 0.4 mM, respectively. A Nai-dependent Ca2+ influx was also observed in Tris-SW. This Ca2+ influx also required [Ca2+]i greater than 10(-8) M. Internal Ca2+ activated a Nai-independent Ca2+ influx from LiSW (tracer Ca/Ca exchange), but in Tris-SW virtually all of the Cai-activated Ca2+ influx was Nai-dependent (Na/Ca exchange). Half-maximal activation was observed with [Na+]i = 30 mM. The fact that internal Ca2+ activates both a Cao-dependent Na+ efflux and a Nai-dependent Ca2+ influx in Tris-SW implies that these two fluxes are coupled; the activating (intracellular) Ca2+ does not appear to be transported by the exchanger. The maximal (calculated) Nai-dependent Ca2+ influx was -25 pmol/cm2.s. At various [Na+]i between 6 and 106 mM, the ratio of the Cao-dependent Na+ efflux to the Nai-dependent Ca2+ influx was 2.8-3.2:1 (mean = 3.1:1); this directly demonstrates that the stoichiometry (coupling ratio) of the Na/Ca exchange is 3:1. These observations on the coupling ratio and kinetics of the Na/Ca exchanger imply that in resting cells the exchanger turns over at a low rate because of the low [Ca2+]i; much of the Ca2+ extrusion at rest (approximately 1 pmol/cm2.s) is thus mediated by an ATP-driven Ca2+ pump.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2769225

Rasgado-Flores, H; Santiago, E M; Blaustein, M P

1989-06-01

165

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

166

Kinetic and thermodynamic uranyl (II) adsorption process into modified Na-Magadiite and Na-Kanemite.  

PubMed

The compound 2-mercaptopyrimidine (MPY) was attached onto synthetic Na-Magadiite (M) and Na-Kanemite (K) samples by homogeneous route. The final matrices named M(MPY) and K(MPY) have been characterized through X-ray powder diffraction and scanning electron microscopy (SEM). The resulted materials were submitted to process of adsorption with uranyl solution at pH 2.0 and 298+/-1K. The kinetic parameters were analyzed by the Lagergren and Elovich models of adsorption and demonstrated to be good fit for all experiments. From calorimetric determinations the quantitative thermal effects for uranyl(II)/basic center interactions gave exothermic enthalpy, negative Gibbs free energy, and positive entropy. These thermodynamic data confirmed the energetically favorable condition of such interactions at the solid/liquid interface for all systems. PMID:19155125

Guerra, Denis Lima; Pinto, Alane Azevedo; de Souza, Janana Azevedo; Airoldi, Claudio; Viana, Rbia Ribeiro

2009-07-30

167

H + , Na + , K + , and Amino Acid Transport in Caterpillar and Larval Mosquito Alimentary Canal  

Microsoft Academic Search

\\u000a Two principal strategies are used to energize membranes in living organisms, a Na+ strategy and a voltage strategy. In the Na+ strategy a primary Na+\\/K+ ATPase imposes both Na+ and K+ concentration gradients across cell membranes with Na+ high outside and K+ high inside the cells. The Na+ gradient, ?[Na+] is used to drive diverse secondary transporters. For example, in

William R. Harvey; Bernard A. Okech

168

EDITORIAL: TaCoNa-Photonics 2008 TaCoNa-Photonics 2008  

Microsoft Academic Search

This special section on theoretical and computational nano-photonics features papers presented at the first International Workshop on Theoretical and Computational Nano-Photonics (TaCoNa-Photonics 2008) held in Bad Honnef, Germany, 3-5 December 2008. The workshop covered a broad range of topics related to current developments and achievements in this interdisciplinary area of research. Since the late 1960s, the word `photonics' has been

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

2009-01-01

169

Peroxisome proliferator-activated receptor gamma antagonists decrease Na+ transport via the epithelial Na+ channel.  

PubMed

The epithelial sodium channel (ENaC) is believed to represent the rate-limiting step for sodium absorption in the renal collecting duct. Consequently, ENaC is a central effector affecting systemic blood volume and pressure. Sodium and water transport are dysregulated in diabetes mellitus. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists are currently used in the treatment of type 2 diabetes, although their use remains limited by fluid retention. The effects of PPARgamma agonists on ENaC activity remain controversial. Although PPARgamma agonists were shown to stimulate ENaC-mediated renal salt absorption, probably via the serum- and glucocorticoid-regulated kinase 1, other studies reported that the PPARgamma agonist-induced fluid retention is independent of ENaC activity. Here we confirmed that four chemically distinct PPARgamma agonists [pioglitazone, rosiglitazone, troglitazone, and 15-deoxy-Delta12,14-prostaglandin J2 (PGJ2)] do not enhance Na+ transport in cultured renal collecting duct principal mpkCCDc14 cells, as assessed by short-circuit current measurements. However, the PPARgamma antagonist 2-chloro-5-nitro-N-4-pyridinyl-benzamide (T0070907), and to a lesser extent 2-chloro-5-nitrobenzanilide (GW9662), were found to decrease Na+ reabsorption across mpkCCDc14 cell layers. Furthermore, pretreatment of monolayers with T0070907 diminished the insulin-stimulated sodium transport. PPARgamma agonist PGJ2 did not enhance insulin-stimulated Na+ flux via ENaC. We also show that PPARgamma enhances ENaC activity when all three subunits are reconstituted in Chinese hamster ovary (CHO) cells. GW9662 inhibits ENaC activity when ENaC subunits are coexpressed in CHO cells with PPARgamma. In contrast, rosiglitazone has no effect on ENaC activity. We conclude that PPARgamma activity is important for maintaining basal and insulin-dependent transepithelial Na+ transport and ENaC activity. PMID:19752200

Pavlov, Tengis S; Levchenko, Vladislav; Karpushev, Alexey V; Vandewalle, Alain; Staruschenko, Alexander

2009-12-01

170

Stimulation of Na+/K+ ATPase activity and Na+ coupled glucose transport by ?-catenin.  

PubMed

?-Catenin is a multifunctional protein stimulating as oncogenic transcription factor several genes important for cell proliferation. ?-Catenin-regulated genes include the serum- and glucocorticoid-inducible kinase SGK1, which is known to stimulate a variety of transport systems. The present study explored the possibility that ?-catenin influences membrane transport. To this end, ?-catenin was expressed in Xenopus oocytes with or without SGLT1 and electrogenic transport determined by dual electrode voltage clamp. As a result, expression of ?-catenin significantly enhanced the ouabain-sensitive current of the endogeneous Na(+)/K(+)-ATPase. Inhibition of vesicle trafficking by brefeldin A revealed that the stimulatory effect of ?-catenin on the endogenous Na(+)/K(+)-ATPase was not due to enhanced stability of the pump protein in the cell membrane. Expression of ?-catenin further enhanced glucose-induced current (Ig) in SGLT1-expressing oocytes. In the absence of SGLT1 Ig was negligible irrespective of ?-catenin expression. The stimulating effect of ?-catenin on both Na(+)/K(+) ATPase and SGLT1 activity was observed even in the presence of actinomycin D, an inhibitor of transcription. The experiments disclose a completely novel function of ?-catenin, i.e. the regulation of transport. PMID:20951116

Sopjani, Mentor; Alesutan, Ioana; Wilmes, Jan; Drmaku-Sopjani, Miribane; Lam, Rebecca S; Koutsouki, Evgenia; Jakupi, Muharrem; Fller, Michael; Lang, Florian

2010-11-19

171

Synthesis and Structure of 1D Na6 Cluster Chain with Short Na-Na Distance: Organic like Aromaticity in Inorganic Metal Cluster  

E-print Network

A unique 1D chain of sodium cluster containing (Na6) rings stabilized by a molybdenum containing metalloligand has been synthesized and characterized. DFT calculations show striking resemblance in their aromatic behaviour with the corresponding hydrocarbon analogues

Khatua, S; Chattaraj, P K; Roy, D R; Bhattacharjee*, Manish; Chattaraj*, Pratim K.; Khatua, Snehadrinarayan; Roy, Debesh R.

2006-01-01

172

On the dynamic influence of Na+ in Mercury's magnetotail  

NASA Astrophysics Data System (ADS)

Although initially ionized at low (<10 eV) energies in Mercury's dayside magnetosphere, Na+ ions can become energized via non-adiabatic motion in the plasma sheet to energies as high as several keV. Although present in sufficient abundance to contribute to both plasma pressure and mass density, the collective influence of Na+ has not yet been confirmed. Here, observations by the Fast Imaging Plasma Spectrometer and Magnetometer on the MErcury Surface Space Environment, GEochemistry, and Ranging spacecraft demonstrate that Na+ can contribute substantially to the total pressure in Mercury's plasma sheet. We identify several examples of sustained high fluxes of Na+ particle flux that are shown to contribute to the diamagnetic depressions measured in the plasma sheet. The three-dimensional distribution functions of Na+ for these events are consistent with hot, nearly isotropic Maxwell-Boltzmann distributions. The relative pressure contribution of Na+ to the total plasma sheet content at Mercury is highly asymmetric, increasing from ~1-30% from dawn to dusk. We further identify an increase in magnetic fluctuations near the Na+ gyro-frequency at the dusk-side magnetopause when the Na+ content of the plasma sheet exceeds 1/cc. These fluctuations are non-linear and highly compressive and do not appear to be the simple left-hand-polarized ion cyclotron wave mode. Instead, these waves transition from left-hand near the magnetopause to right-hand polarization deeper inside the magnetosphere, penetrating up to high latitudes.

Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Sundberg, Torbjorn; Boardsen, Scott A.; Anderson, Brian J.; Korth, Haje; Solomon, Sean C.

2014-05-01

173

Performances of the NA48 Liquid Krypton calorimeter  

E-print Network

The NA48 experiments aims at a precise measurement of direct CP violation in the neutral Kaon system. This puts stringent requirements on the electromagnetic calorimeter used to detect photons of average energy 25 GeV. The choice of NA48 is a quasi homogeneous Liquid Krypton calorimeter with fast readout. The operation of this device and the performances achieved are described.

Guillaume Unal

2000-12-05

174

Annelid epithelia as models for electrogenic Na+ transport.  

PubMed

The electrogenic Na(+) absorption across tight epithelia from invertebrates follows the principles analog to the mechanisms found in vertebrates. Extracellular Na(+)-ions pass the apical cell membranes through highly selective Na(+) channels and follow an electrochemical gradient which is sustained by the basolateral Na(+)/K(+)-ATPases. These apical Na(+) channels are selectively blocked by amiloride and represent the rate-limiting target for the control of transcellular Na(+) uptake. Although annelids express ADH-like peptide hormones, they lack the osmoregulatory mineralocorticoid system with the vertebrate-specific key hormone aldosterone. Thus, their epithelia may represent interesting models for investigation of ion transport regulation. While the formation of urine in the nephridia of, for example, leeches had been subject to intensive studies, the investigation of ion transport across their body wall was largely neglected. We use dissected segments of integuments from the limnic leech Hirudo medicinalis and, recently, from the earthworm Lumbricus terrestris for Ussing chamber experiments. We investigate transintegumental ion transport with focus on control of electrogenic Na(+) uptake and the amiloride-sensitive part of it and identified several extracellular factors as peptide hormones, tri- and divalent cations or purinergic molecules with regulatory effects on it. Meanwhile, there exists a macroscopic view on Na(+) absorption; however, other ion transport mechanisms across annelid integuments still await scientific effort. Here we present a concise synopsis about the electrophysiology of annelid integuments to illustrate the state of science and to evaluate whether further studies in this particular field may be of interest. PMID:12421540

Schnizler, Mikael; Krumm, Steffen; Clauss, Wolfgang

2002-11-13

175

Hydration of Na+ in the interlayer of hectorite: a  

E-print Network

1 Hydration of Na+ , Ni2+ , and Sm3+ in the interlayer of hectorite: a quasielastic neutron.com Abstract Quasielastic neutron scattering experiments were performed with Na-hectorite, Ni-hectorite, and Sm-hectorite and bound to the clay surface (inner-sphere complex). The results obtained for the Sm-hectorite were

Paris-Sud XI, Université de

176

Fragmentation of Na3 clusters following He impact: Theoretical analysis  

E-print Network

Fragmentation of Na3 clusters following He impact: Theoretical analysis of fragmentation of Na3 cluster ion fragmentation following excitation by a fast He atom is studied using a theoretical cluster. Four simple fragmentation mechanisms are proposed to describe the major features of the process

Reid, Scott A.

177

BIOLOGICAL SAFETY O N/A Biosafety Cabinets  

E-print Network

: _________________________________________________ _________________________________________________ _________________________________________________ NOTES: LASER SAFETY O N/A __LS-1 Area not posted with appropriate 3b/4 laser sign __LS-2 No lighted Other Laser Safety FindingBIOLOGICAL SAFETY O N/A Biosafety Cabinets ___BS-1 Grates obstructed ___BS-2 Not certified

Entekhabi, Dara

178

Modelo da Gesto da Cadeia de Abastecimento na Construo  

Microsoft Academic Search

Resumo Na indstria em geral, e principalmente na construo, a entrega dos recursos necessrios actividade um factor essencial para o sucesso do negcio. Para tal contribui, em grande medida, a logstica interna da prpria empresa. A definio de um modelo de gesto da cadeia de abastecimento para a indstria da construo , impreterivelmente, uma das formas de optimizar

Tiago Pinho; Jos Telhada; Maria Sameiro Carvalho

179

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

SciTech Connect

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 diagnosed 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.

Hotchkiss, R.S.; Song, S.K.; Ling, C.S.; Ackerman, J.J.; Karl, I.E. (Washington Univ. School of Medicine, St. Louis (USA))

1990-01-01

180

LiNa5Mo9O30  

PubMed Central

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

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

2012-01-01

181

The Na-K-ATPase and Calcium-Signaling Microdomains  

NSDL National Science Digital Library

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

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

2008-08-01

182

Binding energy and geometry of e^+Na  

NASA Astrophysics Data System (ADS)

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

Shertzer, Janine; Ward, S. J.

2010-03-01

183

Feasibility study for a secondary Na/S battery  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

184

Role of Na+,K+-pumps and transmembrane Na+,K+-distribution in muscle function. The FEPS lecture - Bratislava 2007.  

PubMed

Na(+),K(+)-ATPase situated in the plasma membrane mediates active extrusion of Na(+) and intracellular accumulation of K(+). This transport system the Na(+),K(+)-pump is the major regulator of the transmembrane distribution of Na(+) and K(+), and is itself subject to regulation by a wide variety of factors in skeletal muscles. The excitation of skeletal muscles is elicited by a rapid influx of Na(+), followed by an equivalent efflux of K(+) across sarcolemmal and t-tubular membranes. Due to their size and sudden onset, these events constitute the major transport challenge for the Na(+),K(+)-pumps. Skeletal muscles contain the largest single pool of K(+) in the organism. During intense exercise, the Na(+),K(+)-pumps cannot readily reaccumulate K(+) into the muscle cells. Therefore, the working muscles undergo a net loss of K(+), causing up to a doubling of the K(+) concentration in the arterial blood plasma in less than 1 min and even larger increases in interstitial K(+). This may induce depolarization, loss of excitability and force, in particular in muscles, where the excitation-induced passive Na(+),K(+)-fluxes are large. During continuous stimulation of isolated rat muscles, there is a highly significant correlation between the rise in extracellular K(+) and the rate of force decline. Fortunately, excitation increases the Na(+),K(+)-pumping rate within seconds. Thus, maximum activation of up to 20-fold above the resting transport rate may be reached in 10 s, with utilization of all available Na(+),K(+)-pumps. In muscles, where excitability is reduced by pre-exposure to high [K(+)]o, acute activation of the Na(+),K(+)-pumps by hormones or intermittent electrical stimulation restores excitability and contractility. In working muscles, the Na(+),K(+)-pumps, due to rapid activation of their large transport capacity, play a dynamic regulatory role in the from second to second ongoing restoration and maintenance of excitability and force. Excitation is a self-limiting process that depends on the leak/pump ratio for Na(+) and K(+). Acute inhibition of the Na(+),K(+)-pumps with ouabain or downregulation of the Na(+),K(+)-pump capacity clearly reduces contractile endurance in isolated muscles. The Na(+),K(+)-pumps are a limiting factor for contractile force and endurance. This is in particular noted if their capacity is reduced because of inactivity or disease. For these reasons, tight regulation of the Na(+),K(+)-pumps is crucial for the maintenance of plasma K(+), membrane potential and excitability in skeletal muscle. This is achieved by: (1) acute activation of the Na(+),K(+)-pumps elicited by excitation, catecholamines, insulin, insulin-like growth factor I, calcitonins and amylin; and (2) long-term regulation of the content of Na(+),K(+)-pumps exerted by thyroid hormones, adrenal steroids, insulin, training, inactivity, fasting, K(+)-deficiency or K(+)-overload. In conclusion, the Na(+),K(+)-pump is a central target for regulation of Na(+),K(+)-distribution, important for the contractile performance of skeletal muscles, the pathophysiology of several diseases and for therapeutic intervention. PMID:17988242

Clausen, T

2008-03-01

185

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

PubMed Central

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

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

2014-01-01

186

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

PubMed

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

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

2011-10-01

187

Compressibilities of disordered fluoride pyrochlores NaCdZn 2F 7 and NaCaMg 2F 7  

NASA Astrophysics Data System (ADS)

The compressibilities of disordered pyrochlores NaCaMg 2F 7 and NaCdZn 2F 7 (both Fd3m, Z=8) have been studied with X-ray single-crystal and powder diffraction using diamond anvil cells to 6.5 and 9.0 GPa at room temperature, respectively. The compressibility data are fitted with the Murnaghan equations of state. The zero-pressure bulk modulus B0 and the unit-cell volume at ambient pressure V0 (for the fixed first pressure derivative of the bulk modulus B'=4.00) are equal to 83(2) GPa and 1107.12(1.33) 3 for NaCdZn 2F 7 and to 83(5) GPa and 1079.29(2.62) 3 for NaCaMg 2F 7. Upon decreasing the unit-cell volume, the positional x parameter of the F(2) atom increases in NaCdZn 2F 7 but is constant in NaCaMg 2F 7. In both cases, the (Na,Cd)F 8 and (Na,Ca)F 8 cubes become more regular and are softer than the ZnF 6 and MgF 6 octahedra, respectively. Both materials are structurally stable at least to the respective highest pressures reached in this study. These observations are compared to the high-pressure behavior of oxide pyrochlores.

Grzechnik, Andrzej; Posse, Jose Maria; Morgenroth, Wolfgang; Friese, Karen

2007-07-01

188

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

PubMed

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

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

2014-01-01

189

Reevaluation of the $^{22}$Na(p,$?$) reaction rate: Implications for the detection of $^{22}$Na gamma rays from novae  

E-print Network

Understanding the processes which create and destroy $^{22}$Na is important for diagnosing classical nova outbursts. Conventional $^{22}$Na(p,$\\gamma$) studies are complicated by the need to employ radioactive targets. In contrast, we have formed the particle-unbound states of interest through the heavy-ion fusion reaction, $^{12}$C($^{12}$C,n)$^{23}$Mg and used the Gammasphere array to investigate their radiative decay branches. Detailed spectroscopy was possible and the $^{22}$Na(p,$\\gamma$) reaction rate has been re-evaluated. New hydrodynamical calculations incorporating the upper and lower limits on the new rate suggest a reduction in the yield of $^{22}$Na with respect to previous estimates, implying a reduction in the maximum detectability distance for $^{22}$Na $\\gamma$ rays from novae.

D. G. Jenkins; C. J. Lister; R. V. F. Janssens; T. L. Khoo; E. F. Moore; K. E. Rehm; B. Truett; A. H. Wuosmaa; M. Freer; B. R. Fulton; J. Jose

2003-12-16

190

On the 21Na(p,gamma)22Mg thermonuclear rate for 22Na production in novae  

E-print Network

Classical novae are potential sources of gamma-rays, like the 1.275 MeV gamma emission following 22Na beta decay, that could be detected by appropriate instruments on board of future satellites like INTEGRAL. It has been shown that the production of 22Na by novae is affected by the uncertainty on the 21Na(p,gamma)22Mg rate and in particular by the unknown partial widths of the Ex = 5.714 MeV, J^pi = 2^+, 22Mg level. To reduce these uncertainties, we performed shell model calculations with the OXBASH code, compared the results with available spectroscopic data and calculated the missing partial widths. Finally, we discuss the influence of these results on the 21Na(p,gamma)22Mg reaction rate and 22Na synthesis.

Nadya A. Smirnova; Alain Coc

2000-08-16

191

Direct measurements of 22Na(p,g)23Mg resonances and consequences for 22Na production in classical novae  

E-print Network

The radionuclide 22Na is a potential astronomical observable that is expected to be produced in classical novae in quantities that depend on the thermonuclear rate of the 22Na(p,g)23Mg reaction. We have measured the strengths of low-energy 22Na(p,g)23Mg resonances directly and absolutely using a radioactive 22Na target. We find the strengths of resonances at E_p = 213, 288, 454, and 610 keV to be higher than previous measurements by factors of 2.4 to 3.2, and we exclude important contributions to the rate from proposed resonances at E_p = 198, 209, and 232 keV. The 22Na abundances expected in the ejecta of classical novae are reduced by a factor of ~ 2.

A. L. Sallaska; C. Wrede; A. Garcia; D. W. Storm; T. A. D. Brown; C. Ruiz; K. A. Snover; D. F. Ottewell; L. Buchmann; C. Vockenhuber; D. A. Hutcheon; J. A. Caggiano

2010-09-24

192

Raman spectroscopic study of synthesized Na-bearing majoritic garnets  

NASA Astrophysics Data System (ADS)

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)Nature, 318, 553, Okamoto and Maruyama (2003)PEPI, in press, Ringwood and Lovering (1970) EPSL, 7, 371, Ringwood and Major (1971)EPSL, 12, 411, Sobolev and Labrentav (1971)CMP, 31, 1.

Okamoto, K.

2003-12-01

193

Effects of dietary Na+ deprivation on epithelial Na+ channel (ENaC), BDNF, and TrkB mRNA expression in the rat tongue  

Microsoft Academic Search

BACKGROUND: In rodents, dietary Na+ deprivation reduces gustatory responses of primary taste fibers and central taste neurons to lingual Na+ stimulation. However, in the rat taste bud cells Na+ deprivation increases the number of amiloride sensitive epithelial Na+ channels (ENaC), which are considered as the \\

Tao Huang; Frauke Sthler

2009-01-01

194

Ethylene Oxidation over Platinum: In SituElectrochemically Controlled Promotion Using Na??? Alumina and Studies with a Pt(111)\\/Na Model Catalyst  

Microsoft Academic Search

Electrochemically modified ethylene oxidation over a Pt film supported on the Na+ion conductor ??? alumina has been studied over a range of conditions encompassing both promotion and poisoning. The system exhibits reversible behavior, and the data are interpreted in terms of (i) Na-enhanced oxygen chemisorption and (ii) poisoning of the surface by accumulation of Na compounds. At low Na coverages

Ian R. Harkness; Christopher Hardacre; Richard M. Lambert; Ioannis V. Yentekakis; Constantinos G. Vayenas

1996-01-01

195

The C Terminus of Na+,K+-ATPase Controls Na+ Affinity on Both Sides of the Membrane through Arg935*?  

PubMed Central

The Na+,K+-ATPase C terminus has a unique location between transmembrane segments, appearing to participate in a network of interactions. We have examined the functional consequences of amino acid substitutions in this region and deletions of the C terminus of varying lengths. Assays revealing separately the mutational effects on internally and externally facing Na+ sites, as well as E1-E2 conformational changes, have been applied. The results pinpoint the two terminal tyrosines, Tyr1017 and Tyr1018, as well as putative interaction partners, Arg935 in the loop between transmembrane segments M8 and M9 and Lys768 in transmembrane segment M5, as crucial to Na+ activation of phosphorylation of E1, a partial reaction reflecting Na+ interaction on the cytoplasmic side of the membrane. Tyr1017, Tyr1018, and Arg935 are furthermore indispensable to Na+ interaction on the extracellular side of the membrane, as revealed by inability of high Na+ concentrations to drive the transition from E1P to E2P backwards toward E1P and inhibit Na+-ATPase activity in mutants. Lys768 is not important for Na+ binding from the external side of the membrane but is involved in stabilization of the E2 form. These data demonstrate that the C terminus controls Na+ affinity on both sides of the membrane and suggest that Arg935 constitutes an important link between the C terminus and the third Na+ site, involving an arginine-? stacking interaction between Arg935 and the C-terminal tyrosines. Lys768 may interact preferentially with the C terminus in E1 and E1P forms and with the loop between transmembrane segments M6 and M7 in E2 and E2P forms. PMID:19416970

Toustrup-Jensen, Mads S.; Holm, Rikke; Einholm, Anja Pernille; Schack, Vivien Rodacker; Morth, J. Preben; Nissen, Poul; Andersen, Jens Peter; Vilsen, Bente

2009-01-01

196

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

PubMed

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

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

2015-01-20

197

Blockade of Na+ channels in pancreatic ?-cells has antidiabetic effects.  

PubMed

Pancreatic ?-cells express voltage-gated Na(+) channels (NaChs), which support the generation of electrical activity leading to an increase in intracellular calcium, and cause exocytosis of glucagon. Ranolazine, a NaCh blocker, is approved for treatment of angina. In addition to its antianginal effects, ranolazine has been shown to reduce HbA1c levels in patients with type 2 diabetes mellitus and coronary artery disease; however, the mechanism behind its antidiabetic effect has been unclear. We tested the hypothesis that ranolazine exerts its antidiabetic effects by inhibiting glucagon release via blockade of NaChs in the pancreatic ?-cells. Our data show that ranolazine, via blockade of NaChs in pancreatic ?-cells, inhibits their electrical activity and reduces glucagon release. We found that glucagon release in human pancreatic islets is mediated by the Nav1.3 isoform. In animal models of diabetes, ranolazine and a more selective NaCh blocker (GS-458967) lowered postprandial and basal glucagon levels, which were associated with a reduction in hyperglycemia, confirming that glucose-lowering effects of ranolazine are due to the blockade of NaChs. This mechanism of action is unique in that no other approved antidiabetic drugs act via this mechanism, and raises the prospect that selective Nav1.3 blockers may constitute a novel approach for the treatment of diabetes. PMID:24812428

Dhalla, Arvinder K; Yang, Ming; Ning, Yun; Kahlig, Kristopher M; Krause, Michael; Rajamani, Sridharan; Belardinelli, Luiz

2014-10-01

198

Electron scattering in graphene with adsorbed NaCl nanoparticles  

NASA Astrophysics Data System (ADS)

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 main 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.

Drabi?ska, Aneta; Ka?mierczak, Piotr; Bo?ek, Rafa?; Karpierz, Ewelina; Wo?o?, Agnieszka; Wysmo?ek, Andrzej; Kami?ska, Maria; Pasternak, Iwona; Krajewska, Aleksandra; Strupi?ski, W?odek

2015-01-01

199

The rat Na + sulfate cotransporter rNaS2: functional characterization, tissue distribution, and gene ( slc13a4 ) structure  

Microsoft Academic Search

Inorganic sulfate is essential for numerous functions in mammalian physiology. In the present study, we characterized the functional properties of the rat Na+sulfate cotransporter NaS2 (rNaS2), determined its tissue distribution, and identified its gene (slc13a4) structure. Expression of rNaS2 protein in Xenopus oocytes led to a Na+-dependent transport of sulfate that was inhibited by phosphate, thiosulfate, tungstate, selenate, oxalate, and

Paul A. Dawson; Katrina J. Pirlo; Sarah E. Steane; Kim A. Nguyen; Karl Kunzelmann; Yu Ju Chien; Daniel Markovich

2005-01-01

200

The Practice of Research of a Basic Education Teacher Involving Mental Models of the Phases of the Moon and Eclipses. (Spanish Title: La Prctica de Investigacin de un Maestro de Educacin Bsica con El Uso de los Modelos Mentales de Las Fases de la Luna Y Eclipses.) A Prtica de Pesquisa de um Professor do Ensino Fundamental Envolvendo Modelos Mentais de Fases da Lua e Eclipses  

NASA Astrophysics Data System (ADS)

The inclusion of basic education teachers in the survey domain is a controversial issue and fully debated in the academy. The opportunity for a collective work that incorporated school teachers from a public school to a university's group of physics teaching at university allowed us to glimpse the redefinition of the function of a science teacher (a coauthor of this paper) by himself, such that now he includes research on the knowledge construction by students in his teacher practice. The formation of inter-institutional groups for action planning and research in these areas has proved productive for the task of knowledge construction to support educational processes in school, while the university enriches its collection of experiences critically validated, and can consider the results in teachers initial and continued education. The active participation of the teacher in a research group at the university led him to reflect on the possible didactical ways to be described, analyzed and communicated to other teachers. The construction of a pedagogy that took into account the mental models of students on the basic topics of astronomy, and the changes developed resulting from the lessons taught, led to far-reaching consequences on the pedagogy adopted by the teacher, who incorporates now a new vision of science and alternative forms to dialogue with students, essential components for a researcher in Science Education. La inclusin de los maestros de la escuela bsica en el universo de la investigacin es polmica y est en amplio debate en el mundo acadmico. La oportunidad de trabajo colectivo de los maestros de una escuela pblica en Ro de Janeiro con un grupo universitario de enseanza de la fsica nos ha permitido vislumbrar la redefinicin de la funcin de un maestro de ciencias (uno de los coautores de este documento) por l mismo, ahora para incluir la investigacin sobre la construccin del conocimiento por los alumnos en su prctica como docente. La formacin de grupos interinstitucionales para la planificacin de la accin y la investigacin ha resultado productiva para el trabajo de construccin de conocimiento de apoyo a los procesos educativos en la escuela, mientras que la universidad enriquece su coleccin de experiencias validadas, considerando los resultados de la educacin inicial y continua de maestros. La participacin activa del maestro en un grupo de investigacin en la universidad lo llev a reflexiones sobre los posibles caminos didcticos que pueden ser descriptos, analizados y comunicados a los dems docentes. La construccin de una pedagoga propia, que tuvo en cuenta los modelos mentales de los estudiantes sobre los temas bsicos de astronoma, y los cambios desarrollados a partir de las lecciones que ense, trajeron consecuencias de largo alcance sobre la pedagoga adoptada por el maestro, que ahora incorpora una nueva visin de la ciencia y formas alternativas al dilogo con los estudiantes, los componentes esenciales para un investigador en Educacinen Ciencias. A incluso do professor da escola bsica no universo da pesquisa questo controvertida e em pleno debate no meio acadmico. A oportunidade de trabalho coletivo que incorporou professores de uma escola municipal no Rio de Janeiro a um grupo de ensino de Fsica da universidade nos possibilitou vislumbrar a ressignificao da funo de um professor de Cincias (co-autor deste trabalho) por ele prprio, agora passando a incluir a pesquisa sobre a construo de conhecimento pelos alunos em sua prtica como docente. A formao de grupos interinstitucionais para o planejamento de aes e de pesquisas tem-se mostrado produtiva para um trabalho de construo de conhecimentos a fim de subsidiar processos educativos na escola, ao mesmo tempo em que a universidade enriquece seu acervo de experincias validadas criticamente, podendo considerar seus resultados na formao inicial e continuada de professores. A participao ativa do professor num grupo de pesquisa na universidade o

Pessa Queiroz, Glria; Jubitipan Borges de Sousa, Carlos; Auxiliadora Delgado Machado, Maria

2009-12-01

201

Conductivity of Zr-doped Na/sub 3/PO/sub 4/ : a new Na/sup +/ ion conductor  

SciTech Connect

Na/sub 3/PO/sub 4/ forms an extensive range of solid solutions with the replacement mechanism, 4Na/sup +/ in equilibrium Zr/sup 4 +/ and formula Na /sub 3-4x/ Zr /sub x/ PO/sub 4/: 0 < x < 0.20. With increasing x, the conductivity increases markedly and passes through a maximum at x approx. = 0.13 with a value of 2.5 x 10/sup -2/ ohm/sup -1/cm/sup -1/ at 300/sup 0/C. The solid solutions are thermodynamically stable, easily prepared and sinter into dense ceramics at about 1000/sup 0/C.

Milne, S.J.; West, A.R.

1984-06-01

202

Reactions of NaCl with gaseous SO3, SO2, and O2  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

203

Reactions of NaCl with Gaseous SO3, SO2, and O2  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

204

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

E-print Network

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

MacLean, B T; Lattanzio, J

2014-01-01

205

ON RACK COHOMOLOGY P. ETINGOF & M. GRA"NA  

E-print Network

ON RACK COHOMOLOGY P. ETINGOF & M. GRA"NA Abstract.We prove that the lower bounds for Betti numbers of the rack, qu-theoretical interpretation of t* *he second cohomology group for racks. 1.Introduction

Graña, Matías

206

Degradation Of Carbon/Phenolic Composites By NaOH  

NASA Technical Reports Server (NTRS)

Effects of sodium hydroxide contamination level on physical and chemical properties of phenolic resin and carbon/phenolic composites described in report. NaOH degrades both carbon and phenolic components of carbon/phenolic laminates.

King, H. M.; Semmel, M. L.; Goldberg, B. E.; Clinton, Raymond G., Jr.

1989-01-01

207

NaIrO 3A pentavalent post-perovskite  

NASA Astrophysics Data System (ADS)

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

Bremholm, M.; Dutton, S. E.; Stephens, P. W.; Cava, R. J.

2011-03-01

208

Tb/Na tobermorite: Thermal behaviour and high temperature products  

SciTech Connect

By heating a sample of Tb/Na tobermorite we obtained a phase which was identified through its X-ray diffraction (XRD) pattern, as terbium silicate apatite. Subsequently this compound has been directly prepared by solid state reaction and we carried out a structural refinement from XRD data in space group P6{sub 3}/m obtaining cell parameters a=9.39199(4) A and c=6.84041(5) A. Terbium silicate apatite heated in melted NaF led to Tb{sub 4}O{sub 7} crystals. - Graphical Abstract: By heating over 900 deg. C Tb/Na tobermorite a terbium silicate apatite was obtained. The same product has been independently prepared and structurally characterized from powder diffraction data. Attempts of crystallizing terbium silicate apatite from melted NaF led to Tb{sub 4}O{sub 7} crystals.

Garra, Walter [Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, via Risorgimento, 35, 56126 Pisa (Italy); Marchetti, Fabio, E-mail: fama@dcci.unipi.i [Dipartimento di Chimica e Chimica Industriale, Universita di Pisa, via Risorgimento, 35, 56126 Pisa (Italy); Merlino, Stefano [Dipartimento di Scienze della Terra, Universita di Pisa, via S. Maria, 53, 56126 Pisa (Italy)

2009-06-15

209

Triple-point wetting of Xe on NaF  

NASA Astrophysics Data System (ADS)

We have measured high-precision adsorption isotherms of Xe on NaF by using a torsional oscillator microbalance. In contrast to theoretical predictions, we find that this system undergoes triple-point wetting.

Bruschi, L.; Mistura, G.

1998-07-01

210

Nac onal~na akadem nauk Ukra ni KONDENSOVANIH  

E-print Network

nn . I.M.Mpiglod, A.M.Gaqkeviq Anotac . Na osnovi metodu nepivnova nogo statistiqnogo Zuba- p va dl dovil~nogo nabopu dinamiqnih zminnih otpimani zagal~ni pivn nn teopi lini no pelaksaci ppostih pidin

211

NaIrO3A Pentavalent Post-perovskite  

SciTech Connect

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

M Bremholm; S Dutton; P Stephens; R Cava

2011-12-31

212

Nuclear spin-lattice relaxation in the sodium anion, Na -  

NASA Astrophysics Data System (ADS)

We report direct measurements of nuclear spin-lattice relaxation times (T1n) for the sodium anion, Na-, in solutions containing both sodium and a heavier alkali metal in 1,4,7,10-tetraoxacyclododecane (12-crown-4, 12C4). Nuclear spin-lattice relaxation in Na- is found to be essentially independent of the alkali counterion and to depend only weakly upon the concentration of sodide ion in solution. The temperature dependence of T1n for Na- was used to determine an activation energy for the processes responsible for spin relaxation. The results are consistent with a dominant, but very inefficient, quadrupolar relaxation mechanism which involves the modulation of the electric field gradient at Na- via the reorientation and/or translational motion of surrounding 12C4 molecules in the liquid. Furthermore, we find that solvation of Na- in 12C4 as well described by a model in which there is neither preferential orientation of 12C4 molecules nor a clearly identifiable first solvation shell around the sodide ion. Consistent with this description, the activation energies for the processes responsible for spin-lattice relaxation in Na- are close to those observed for the processes causing 1H and 13C relaxation in the neat liquid crown. We outline two methods, which take into account electron-electron correlation effects, for determining the Sternheimer antishielding factor ?2 for the sodium anion. The most realistic estimate for ?2 (-14.98) is used to calculate the NMR linewidth for Na- when it is associated with an uncomplexed (unsolvated) sodium cation and also in the contact and solvent-separated Na+-Na- ion pairs. A rms value of 0.03 MHz for the quadrupole coupling constant (e2qQ/?) of Na- in 12C4 solutions is deduced. We conclude that Na- in these solutions suffers only minor perturbations on its gas-phase electronic structure; neither does it exist as part of a contact or solvent-separated ion pair. It appears that the sodide ion represents the closest realization of a gas-like ionic moiety in solution.

Holton, Dolores M.; Ellaboudy, Ahmed; Pyper, Nicholas C.; Edwards, Peter P.

1986-02-01

213

Single Na+ channel currents observed in cultured rat muscle cells  

Microsoft Academic Search

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

Frederick J. Sigworth; Erwin Neher

1980-01-01

214

Substructure of membrane-bound Na + ?K + ATPase protein  

Microsoft Academic Search

Purified membrane-bound Na+-K+-ATPase from rat kidney outer medulla was studied by freeze-fracturing, by freeze-etching and by negative staining. Freeze-fracturing of purified Na+-K+-ATPase membranes shows intramembraneous particles with a diameter of about 100 . The frequency of these intramembraneous particles as estimated from the particle densities on the two fracture faces lies between 4700 and 5600 particles per m2.

W. Haase; H. Koepsell

1979-01-01

215

Broad-band structured fluorescence from NaI  

Microsoft Academic Search

The emission spectrum of a molecular beam of NaI has been measured following excitation by the 248 nm KrF line of an excimer laser. The fluorescence structure, and the lifetime (172 ns), indicate the presence of a bound upper state not previously characterized. We identify this state as correlating with Na(3 2P)+I(5 2P3\\/2) atoms. Through numerical simulation using a Morse

R. D. Bower; P. Chevrier; P. Das; H. J. Foth; J. C. Polanyi; M. G. Prisant; J. P. Visticot

1988-01-01

216

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

PubMed

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

Schlegel, Katharina; Mller, Volker

2013-02-01

217

Comparative effects of chemical amendments on salt and NA leaching  

Microsoft Academic Search

Efficiency of sodic soil reclamation is thought to vary with types of chemicals used. This study examined the effects of five inorganic (H2SO4, CaCl2 2H2O, CaSO4 2H2O, FeSO4, Al2(SO4)3) and two organic compounds (polyacrylamide, and trihydroxy glutaric acid) on the rate and the extent of salt and Na leaching in moderately Na-affected saline soils: Saneli silty clay loam

S. Miyamoto; C. Enriquez

1990-01-01

218

Effect of pH on Na induced Ca deficiency  

Microsoft Academic Search

Although it is well known that high Na concentrations induce Ca deficiency in acidic conditions, the effect of high pH on\\u000a this competitive mechanism is not so well understood. The effect of Ca activity ratio (CAR) and pH on the Ca uptake of mungbeans\\u000a (Vigna radiata (L.) Wilczek cv. Emerald) and Rhodes grass (Chloris gayana cv. Pioneer) in Na dominated

Peter M. Kopittke; Neal W. Menzies

2005-01-01

219

Resonance reaction rate of 21Na(p,?)22Mg  

Microsoft Academic Search

By using the new Coulomb screening model and most recent experimental results, this paper calculates the resonance reaction rates of 21Na(p,?)22Mg. The derived result shows that the effect of electron screening on resonant reaction is prominent in astrophysical interesting temperature range. In conjunction with the experimental results, the recommended rates of21Na(p,?)22Mg would increase at least 10%, which undoubtedly affect the

Liu Hong-Lin; Liu Men-Quan; Liu Jing-Jing; Luo Zhi-Quan

2007-01-01

220

Wall relaxation rates for an optically pumped Na vapor  

NASA Astrophysics Data System (ADS)

The wall relaxation rates for an optically pumped Na vapor have been measured for a variety of wall surfaces. We find that fluorocarbon rubber (Fluorel or Viton) at a temperature of 250C has a relaxation rate that corresponds on the average to 10-15 bounces before depolarization occurs. A surface with a relaxation rate this small is potentially very important for use in the polarized Na vapor charge exchange target used in the optically pumped polarized H - ion source.

Swenson, D. R.; Anderson, L. W.

1985-08-01

221

Status and plans of the NA61/SHINE physics program  

SciTech Connect

One of the NA61/SHINE experiment's goals is to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. This is to be achieved by performing a two-dimensional phase diagram (T- Micro-Sign {sub B}) scan-measuring hadron production in collisions of various beam particles and targets at various beam energies. NA61/SHINE also collects data for the T2K experiment, which are just about to be published.

Czopowicz, T., E-mail: Tobiasz.Roman.Czopowicz@cern.ch [Warsaw University of Technology, Faculty of Physics (Poland)

2012-06-15

222

Na + Xe collisions in the presence of two nonresonant lasers  

NASA Technical Reports Server (NTRS)

Na+Xe collisions in the presence of two distinct laser fields (rhodamine 110 and Nd:glass) are investigated with reference to the response to nonresonant radiation of alkali metals collisionally perturbed by a buffer gas. It is found that the excited Na-asterisk (4s)+Xe state is produced with a measurable cross section due to two-photon absorption with field intensities as low as 10 MW/sq cm.

De Vries, P. L.; Chang, C. H.; George, T. F.; Laskowski, B.; Stallcop, J. R.

1980-01-01

223

Kinetics of the Reverse Mode of the Na + \\/Glucose Cotransporter  

Microsoft Academic Search

This study investigates the reverse mode of the Na+\\/glucose cotransporter (SGLT1). In giant excised inside-out membrane patches from Xenopus laevis oocytes expressing rabbit SGLT1, application of a-methyl-D-glucopyranoside (aMDG) to the cytoplasmic solution induced an outward current from cytosolic to external membrane surface. The outward current was Na+- and sugar-dependent, and was blocked by phlorizin, a specific inhibitor of SGLT1. The

S. Eskandari; E. M. Wright; D. D. F. Loo

2005-01-01

224

Expression of epithelial Na channels in Xenopus oocytes  

Microsoft Academic Search

Epithelial Na channel activity was expressed in oocytes from Xenopus laev\\/s after injection of mRNA from A6 cells, derived from Xenopus kidney. Poly A(+) RNA was extracted from confluent cell monolayers grown on either plastic or permeable supports. 1-50 ng RNA was injected into stage 5-6 oocytes. Na channel activity was assayed as amiloride-sensitive current (Isa) under voltage-clamp condi- tions

LAWRENCE G. PALMER; IRENE CORTHESY-THEULAZ; HANS-PETER GAEGGELER; JEAN-PIERRE KRAEHENBUHL; BERNARD ROSSIER

1990-01-01

225

Electrogenic Na + \\/K + -transport in human endothelial cells  

Microsoft Academic Search

Na+\\/K+ pump currents were measured in endothelial cells from human umbilical cord vein using the whole-cell or nystatin-perforated-patch-clamp technique combined with intracellular calcium concentration ([Ca2+]i) measurements with Fura-2\\/AM. Loading endothelial cells through the patch pipette with 40 mmol\\/l [Na+] did not induce significant changes of [Ca2+]i. Superfusing the cells with K+-free solutions also did not significantly affect [Ca2+]i. Reapplication of

Masahiro Oike; Guy Droogmans; Rik Casteels; Bernd Nilius

1993-01-01

226

Na-caseinate/oil/water systems: emulsion morphology diagrams.  

PubMed

The concentrated (dispersed phase 50-70 wt%) composition space of Na-caseinate, a family of milk proteins, stabilised emulsions was investigated for three different oils: soybean oil, palm olein and tetradecane with pH 6.8 phosphate buffer continuous phase. The variation of emulsion stability and microstructure were explored using static light scattering, diffusion nuclear magnetic resonance, cryo-scanning electron microscopy, rheology and the time varying macroscopic phase separation of the emulsions. For soybean oil and palm olein a rich diversity of emulsion microstructures and stabilities are realised. Five emulsion domains, each having a different microstructure and macroscopic stability have been identified within the composition space probed. For the lowest concentrations of emulsifier bridging flocculation is evident and emulsions are of low stability. Increasing Na-caseinate concentration leads to an increased stability and the existence of distinct individual oil droplets, visualised using cryo-scanning electron microscopy. Further increases in Na-caseinate concentration reduce emulsion stability due to depletion flocculation. Na-caseinate self-assembly is then initiated. At sufficiently high Na-caseinate and/or oil concentrations the continuous phase of the emulsion is a three-dimensional protein network and emulsion stability is again enhanced. At the limits of the emulsion composition space a gel-like paste is formed. The diversity of emulsion microstructure is reduced when tetradecane is the discrete phase. Na-caseinate self-assembly is limited and there is no evidence for formation of a protein network. PMID:22709624

Tan, Hui Lin; McGrath, Kathryn M

2012-09-01

227

Regulation of Na,K-ATPase during acute lung injury.  

PubMed

A hallmark of acute lung injury is the accumulation of a protein rich edema which impairs gas exchange and leads to hypoxemia. The resolution of lung edema is effected by active sodium transport, mostly contributed by apical Na(+) channels and the basolateral located Na,K-ATPase. It has been reported that the decrease of Na,K-ATPase function seen during lung injury is due to its endocytosis from the cell plasma membrane into intracellular pools. In alveolar epithelial cells exposed to severe hypoxia, we have reported that increased production of mitochondrial reactive oxygen species leads to Na,K-ATPase endocytosis and degradation. We found that this regulated process follows what is referred as the Phosphorylation-Ubiquitination-Recognition-Endocytosis-Degradation (PURED) pathway. Cells exposed to hypoxia generate reactive oxygen species which activate PKC zeta which in turn phosphorylates the Na,K-ATPase at the Ser18 residue in the N-terminus of the alpha1-subunit leading the ubiquitination of any of the four lysines (K16, K17, K19, K20) adjacent to the Ser18 residue. This process promotes the alpha1-subunit recognition by the mu2 subunit of the adaptor protein-2 and its endocytosis trough a clathrin dependent mechanism. Finally, the ubiquitinated Na,K-ATPase undergoes degradation via a lysosome/proteasome dependent mechanism. PMID:17972021

Lecuona, Emilia; Trejo, Humberto E; Sznajder, Jacob I

2007-12-01

228

Band gap engineering for graphene by using Na+ ions  

NASA Astrophysics Data System (ADS)

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 (Eg) at DP in a controlled way by depositing positively charged Na+ ions on single layer graphene formed on 6H-SiC(0001) surface. The doping of low energy Na+ ions is found to deplete the ?* band of graphene above the DP, and simultaneously shift the DP downward away from Fermi energy indicating the opening of Eg. The band gap increases with increasing Na+ coverage with a maximum E g ? 0.70 eV. Our core-level data, C 1s, Na 2p, and Si 2p, consistently suggest that Na+ 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+ ions, which may play a vital role in utilizing graphene in future nano-electronic devices.

Sung, S. J.; Lee, P. R.; Kim, J. G.; Ryu, M. T.; Park, H. M.; Chung, J. W.

2014-08-01

229

Simultaneous optical excitation of Na electronic and CF{sub 4} vibrational modes in Na+CF{sub 4} collisions  

SciTech Connect

We report on the ultraviolet excitation of Na(3s)+CF{sub 4} collision pairs in a crossed molecular beam experiment. We observe Na(3d) collision products originating from the process Na(3s)+CF{sub 4}({nu}{sub 3}=0)+h{nu}{yields}Na(3d)+CF{sub 4}({nu}{sub 3}=1). The spectral intensity distribution of the collision products and the prevailing small angle scattering confirm a previously proposed long range dipole-dipole mechanism. We report velocity-resolved spectra and a comparison to preliminary numerical results based on collisional broadening theory. Polarization experiments suggest future potential for the observation of collision geometries.

Alekseev, V. A. [Department of Physics, St. Petersburg State University, Peterhof 198504 (Russian Federation); Grosser, J.; Hoffmann, O. [Institut fuer Gravitationsphysik, Leibniz Universitaet Hannover, 30167 Hannover (Germany); Rebentrost, F. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany)

2008-11-28

230

NaCl nanodroplet on NaCl(1 0 0) at the melting point  

NASA Astrophysics Data System (ADS)

The self-wetting properties of ionic crystal surfaces are studied, using NaCl(1 0 0) as a prototype case. The anomalously large contact angle measured long ago by Mutaftschiev [Surf. Sci. 47 (1975) 723; J. Cryst. Growth 182 (1997) 205] is well reproduced by realistic molecular dynamics simulations. Based on these results, and on independent determinations of the liquid-vapor ( ?LV) and the solid-vapor interface free energy ( ?SV) [Zykova-Timan et al. to be published], an estimate of the solid-liquid interface free energy ( ?SL) is extracted. The solid-vapor surface free energy turns out to be small and similar to the liquid-vapor one, providing a direct thermodynamic explanation of the reduced wetting ability of the ionic melt.

Zykova-Timan, T.; Tartaglino, U.; Ceresoli, D.; Sekkal-Zaoui, W.; Tosatti, E.

2004-09-01

231

Salt resistance of chickpea genotypes in solutions salinized with NaCl or Na 2 SO 4  

Microsoft Academic Search

SummaryTo assess the potential for developing a salt resistant cultivar of chickpea (Cicer arietinum L.) 160 genotypes were screened for percent survival after 9 weeks in greenhouse solution cultures, with 50 mM NaCl or 25 mM Na2SO4. All plants grew well in the sulfate treatment but only cv. L-550 survived the chloride treatment. Salt damage appeared and\\u000a developed slowly.\\u000a \\u000a To

D. J. Lauter; D. N. Munns

1986-01-01

232

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

PubMed Central

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

Babes, A; Fendler, K

2000-01-01

233

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

Microsoft Academic Search

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

MASAKAZU NAKAO; DAVID C. GADSBY

1989-01-01

234

Targeting Voltage Gated Sodium Channels NaV1.7, NaV1.8, and NaV1.9 for Treatment of Pathological Cough  

PubMed Central

Recent advances in our understanding of voltage-gated sodium channels (NaVs) lead to the rational hypothesis that drugs capable of selective blockade of NaV subtypes may be a safe and effective strategy for the treatment of unwanted cough. Among the nine NaV subtypes (NaV1.1NaV1.9), the afferent nerves involved in initiating cough, in common with nociceptive neurons in the somatosensory system, express mainly NaV1.7, NaV1.8, and NaV1.9. Although knowledge about the effect of selectively blocking these channels on the cough reflex is limited, their biophysical properties indicate that each may contribute to the hypertussive and allotussive state that typifies subacute and chronic nonproductive cough. PMID:24272479

Muroi, Yukiko

2015-01-01

235

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

PubMed Central

Na+/K+ pumps move net charge through the cell membrane by mediating unequal exchange of intracellular Na+ and extracellular K+. Most charge moves during transitions that release Na+ to the cell exterior. When pumps are constrained to bind and release only Na+, a membrane voltage-step redistributes pumps among conformations with zero, one, two or three bound Na+, thereby transiently generating current. By applying rapid voltage steps to squid giant axons, we previously identified three components in such transient currents, with distinct relaxation speeds: fast (which nearly parallels the voltage-jump time course), medium speed (?m=0.20.5?ms) and slow (?s=110?ms). Here we show that these three components are tightly correlated, both in their magnitudes and in the time courses of their changes. The correlations reveal the dynamics of the conformational rearrangements that release three Na+ to the exterior (or sequester them into their binding sites) one at a time, in an obligatorily sequential manner. PMID:22334072

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

2012-01-01

236

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

PubMed

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

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

2012-01-01

237

?3 subunit of Na,K ATPase regulates T cell activation with no involvement of Na,K ATPase activity.  

PubMed

Na,K ATPase plays an important role in the regulation of Na(+) and K(+) ions that are required for normal resting membrane potential and various cellular functions. Na,K ATPase is composed of two subunits, ? and ? subunits. Engagement of the ? subunit by an agonistic monoclonal antibody (mAb) P-3E10 inhibited T cell activation and induced the G0/G1 cell cycle arrest. In addition, mAb P-3E10 decreased CD25 expression. The mAb P-3E10, however, did not inhibit the proliferation of cell lines and the phagocytosis activity of phagocytes, and did not interfere with the Na,K ATPase activity. These results indicate that mAb P-3E10 reacts to the ? subunit and, as a consequence, brings about the regulation of the T cell activation without disturbing the Na,K pump activity. By sequential immunoprecipitation, we demonstrated the expression of the ?3 subunit free form apart from the ? subunit. In this study, we propose that the ?3 subunits of Na,K ATPase are expressed separately from the ? subunit, and play a role in regulation of the immune response. PMID:25678464

Chruewkamlow, Nuttapol; Pata, Supansa; Mahasongkram, Kodchakorn; Laopajon, Witida; Kasinrerk, Watchara; Chiampanichayakul, Sawitree

2015-05-01

238

A sodium calcium arsenate, NaCa(AsO(4)).  

PubMed

The title compound, NaCa(AsO(4)), was synthesized using a hydro-thermal method at 633-643?K. It has a dense structure composed of alternating layers of distorted [CaO(6)] octa-hedra and layers of [AsO(4)] tetra-hedra and distorted [NaO(6)] octa-hedra, stacked along the a axis. The As, Ca and two O atoms lie on the mirror plane at y = 1/4 (i.e. 4c), while the Na atom lies on an inversion centre (1/2, 1/2, 0) (i.e. 4b). Each distorted [CaO(6)] octa-hedron shares four equatorial common O vertices with four neighboring octa-hedra, forming a layer parallel to (100), whereas each distorted [NaO(6)] octa-hedron shares two opposite edges with two neighboring ones, forming a chain running along [010]. Each isolated [AsO(4)] tetra-hedron shares two edges with two different [NaO(6)] octa-hedra in one [NaO(6)] chain and a vertex with another chain. Simultaneously the above [AsO(4)] tetra-hedron located in a four-membered [CaO(6)] ring shares one edge of its base facet with one [CaO(6)] octa-hedron and three corners with three other [CaO(6)] octa-hedra of one [CaO(6)] layer, and the remaining apex is shared with another [CaO(6)] layer. [NaO(6)] octa-hedra and [CaO(6)] octa-hedra are linked to each other by sharing edges and vertices. PMID:22199467

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

2011-12-01

239

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

PubMed

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

Nehm, Benjamin; Henry, Mlaine; Mouginot, Didier; Drolet, Guy

2012-01-01

240

Identification of Nocobactin NA Biosynthetic Gene Clusters in Nocardia farcinica?  

PubMed Central

We identified the biosynthetic gene clusters of the siderophore nocobactin NA. The nbt clusters, which were discovered as genes highly homologous to the mycobactin biosynthesis genes by the genomic sequencing of Nocardia farcinica IFM 10152, consist of 10 genes separately located at two genomic regions. The gene organization of the nbt clusters and the predicted functions of the nbt genes, particularly the cyclization and epimerization domains, were in good agreement with the chemical structure of nocobactin NA. Disruptions of the nbtA and nbtE genes, respectively, reduced and abolished the productivity of nocobactin NA. The heterologous expression of the nbtS gene revealed that this gene encoded a salicylate synthase. These results indicate that the nbt clusters are responsible for the biosynthesis of nocobactin NA. We also found putative IdeR-binding sequences upstream of the nbtA, -G, -H, -S, and -T genes, whose expression was more than 10-fold higher in the low-iron condition than in the high-iron condition. These results suggest that nbt genes are regulated coordinately by IdeR protein in an iron-dependent manner. The ?nbtE mutant was found to be impaired in cytotoxicity against J774A.1 cells, suggesting that nocobactin NA production is required for virulence of N. farcinica. PMID:21097631

Hoshino, Yasutaka; Chiba, Kazuhiro; Ishino, Keiko; Fukai, Toshio; Igarashi, Yasuhiro; Yazawa, Katsukiyo; Mikami, Yuzuru; Ishikawa, Jun

2011-01-01

241

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

PubMed

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

Welch, W J

2015-01-01

242

Na[superscript +] binding to meizothrombin desF1  

SciTech Connect

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 k 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.

Papaconstantinou, M.E.; Gandhi, P.S.; Chen, Z.; Bah, A.; Di Cera, E. (WU-MED)

2009-06-10

243

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

PubMed Central

Adenosine type 1 receptor (A1-AR) antagonists induce diuresis and natriuresis in experimental animals and humans. Much of this effect is due to inhibition of A1-ARs in the proximal tubule, which is responsible for 6070% of the reabsorption of filtered Na+ and fluid. Intratubular application of receptor antagonists indicates that A1-AR mediates a portion of Na+ uptake in PT and PT cells, via multiple transport systems, including Na+/H+ exchanger-3 (NHE3), Na+/PO4? co-transporter and Na+-dependent glucose transporter, SGLT. Renal microperfusion and recollection studies have shown that fluid reabsorption is reduced by A1-AR antagonists and is lower in A1-AR KO mice., compared to WT mice. Absolute proximal reabsorption (APR) measured by free-flow micropuncture is equivocal, with studies that show either lower APR or similar APR in A1-AR KO mice, compared to WT mice. Inhibition of A1-ARs lowers elevated blood pressure in models of salt-sensitive hypertension, partially due to their effects in the proximal tubule. PMID:25345761

Welch, William J

2015-01-01

244

Preparation and characterization of NaCS-CMC/PDMDAAC capsules.  

PubMed

A novel capsule system composed of sodium cellulose sulfate (NaCS), carboxymethyl cellulose (CMC) and poly[dimethyl(diallyl)ammonium chloride] (PDMDAAC) was prepared for improving the properties of NaCS/PDMDAAC capsules. The process parameters, such as CMC concentration (0, 2, 4, 6 and 8 g/L), NaCS concentration (20, 25, 30, 35 and 40 g/L), PDMDAAC concentration (20, 30, 40, 50, 60, 70 and 80 g/L), reaction time and temperature were investigated to understand their effects on the diameter, membrane thickness and mechanical strength of capsules. The optimum operation conditions for preparing NaCS-CMC/PDMDAAC capsules were determined as 6-8 g/L CMC, 35-40 g/L NaCS, 60 g/L PDMDAAC and polymerization for 30-40 min. Diffusion of substances with low molecular weight into capsules was investigated, and diffusion coefficients were calculated according to the developed model. The yeast of Candida krusei was chosen as representative cell to evaluate the effects of different cell loading on capsule mechanical strength. Meanwhile the encapsulated osmophilic C. krusei cells were cultured in 250 mL shaking flasks for 72 h to determine the cell leaking properties in short and long term. PMID:16199144

Chen, Guo; Yao, Shan-jing; Guan, Yi-xin; Lin, Dong-qiang

2005-11-10

245

Multiatom covalent bonding and the formation enthalpy of Na2K  

NASA Astrophysics Data System (ADS)

We have made accurate pseudopotential calculations of the total energy of Na, K, and NaK in the CsCl structure, and Na2K in the MgZn2 structure. For Na2K, the only ordered alloy known to exist, we obtained a formation enthalpy, H=-16.1 meV/atom, whereas for NaK we obtained H=+7.5 meV/atom. We argue that the negative H of Na2K is a consequence of unusual covalent bonds involving more than two Na atoms.

Zhu, Ming J.; Bylander, D. M.; Kleinman, Leonard

1996-06-01

246

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

PubMed

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

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

247

A construo das estradas de ferro na Argentina no final do sculo XIX: a influncia das companhias inglesas  

Microsoft Academic Search

No final do sculo XIX a Argentina experimentou uma fase de grande crescimento econmico, a Belle poque, representado por uma forte presena de produtos, trabalho e especialmente de capital externo. Este capital, que entrou no pas atravs de investimento externo, foi principalmente britnico e direcionado para a construo de estradas de ferro. A sua necessidade foi devida a grande expanso

Maria Heloisa Lenz

248

High-NA HPCS optical fibers for medical diagnosis and treatment  

NASA Astrophysics Data System (ADS)

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

Skutnik, Bolesh J.

2010-02-01

249

Inelastic cold collisions of a Na/Rb mixture in a magneto-optical trap  

NASA Astrophysics Data System (ADS)

We report results on inelastic cold collisions for a mixed species magneto-optical trap containing Na and Rb. The rate of collisional trap loss of Na is due to different contributions: Na-Na and Na-Rb collisions. Both parts are investigated with respect to trap laser intensity and frequency. The observations are explained based on a Gallagher-Pritchard model. Possibilities for studies and applications involving mixed species traps are discussed.

Telles, G. D.; Marcassa, L. G.; Muniz, S. R.; Miranda, S. G.; Antunes, A.; Westbrook, C.; Bagnato, V. S.

1999-01-01

250

Multibubble sonoluminescence pulses from Na atoms in viscous liquid.  

PubMed

Multibubble sonoluminescence pulses of Na and continuum emissions were measured from NaCl-ethylene glycol solution saturated with Xe at 28 kHz. The Na emission consisted of multiple-peak pulses and single pulses. The intrinsic pulse width estimated from single pulses was 0.37 ns, which differs from 10-165 ns obtained by previous work. High-speed shadowgraphs of bubble dynamics and high-speed movies (32000 fps) of sonoluminescence were observed. The observations suggest that the multiple-peak pulse is due to the superposition of single peaks resulting from bubbles fragmented from a characteristic bubble which repeats the fragmentation and coalescence. This phenomenon may be specific to viscous liquids. PMID:22559461

Choi, Pak-Kon; Sawada, Yosuke; Takeuchi, Yuuta

2012-05-01

251

Superconducting properties and electronic structure of NaBi.  

PubMed

Resistivity, dc magnetization, and heat capacity measurements are reported for superconducting NaBi. T(c), the electronic contribution to the specific heat ?, the ?C(p)/?T(c) ratio, and the Debye temperature are found to be 2.15?K, 3.4?mJ?mol(-1)?K(-2), 0.78, and 140?K respectively. The calculated electron-phonon coupling constant (?(ep) = 0.62) implies that NaBi is a moderately coupled superconductor. The upper critical field and coherence length are found to be 250?Oe and 115?nm, respectively. Electronic structure calculations show NaBi to be a good metal, in agreement with the experiments; the p(x) and p(y) orbitals of Bi dominate the electronic states at the Fermi Energy. PMID:24804822

Kushwaha, S K; Krizan, J W; Xiong, J; Klimczuk, T; Gibson, Q D; Liang, T; Ong, N P; Cava, R J

2014-05-28

252

Investigation of the 19Na via resonance elastic scattering  

E-print Network

The structure of the unbound proton-rich isotope 19Na was studied in resonance elastic scattering of a radioactive 18Ne beam on a proton target using the thick-target inverse-kinematics method. The experiment covered excitation energy range from 0.5 to 2.7 MeV in c.m.s. Only one state of 19Na (the second excited state) was observed. A combined R-matrix and potential-model analysis was performed. The spin and parity assignment of this second excited state was confirmed to be 1/2+. We showthat the position of the 1/2+ state significantly affects the reaction rate through that state but the total reaction rate remains unchanged since the 18Ne(2p,gamma) proceeds mostly via the ground and first excited states in 19Na at stellar temperatures.

B. B. Skorodumov; G. V. Rogachev; P. Boutachkov; A. Aprahamian; J. J. Kolata; L. O. Lamm; M. Quinn; A. Woehr

2006-09-26

253

Investigation of the 19Na via resonance elastic scattering  

E-print Network

The structure of the unbound proton-rich isotope 19Na was studied in resonance elastic scattering of a radioactive 18Ne beam on a proton target using the thick-target inverse-kinematics method. The experiment covered excitation energy range from 0.5 to 2.7 MeV in c.m.s. Only one state of 19Na (the second excited state) was observed. A combined R-matrix and potential-model analysis was performed. The spin and parity assignment of this second excited state was confirmed to be 1/2+. We showthat the position of the 1/2+ state significantly affects the reaction rate through that state but the total reaction rate remains unchanged since the 18Ne(2p,gamma) proceeds mostly via the ground and first excited states in 19Na at stellar temperatures.

Skorodumov, B B; Boutachkov, P; Kolata, J J; Lamm, L O; Quinn, M; Rogachev, G V; Whr, A

2006-01-01

254

Binding energy and structure of e+Na  

NASA Astrophysics Data System (ADS)

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

Shertzer, J.; Ward, S. J.

2010-06-01

255

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

SciTech Connect

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

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

1989-08-01

256

Diseo de un programa de base de datos para el seguimiento de pacientes, aplicando el Real Decreto 1566\\/1998 sobre control de calidad en radioterapia  

Microsoft Academic Search

Resumen\\u000a IntroduccinEn julio de 1999, siguiendo el Real Decreto 1566\\/1998 y las normas ISO 9002, fue diseado un programa informtico para analizar\\u000a anualmente toxicidad, control de la enfermedad y supervivencia.\\u000a \\u000a \\u000a \\u000a Material y mtodosSe analizaron un total de 2.192 pacientes tratados en el Servicio de Oncologa Radioterpica hasta mayo de 2005. El 51,8%\\u000a de los pacientes fueron estadios iniciales y el

Jos Lpez Torrecilla; Desamparados Gonzlez Sanchis; Ana Hernndez Machancoses; Piedad Almendros Blanco; Enrique Garca Miragall; Eugenio Lpez Taberner

2004-01-01

257

Plant response to Na/sup +/, K/sup +/ and K/sup +//Na/sup +/ ratios under saline conditions  

SciTech Connect

This research was undertaken to more clearly determine plant response to saline-sodic waters. In the first experiment, the response of wheat and sorghum to different K/sup +//Na/sup +/ ratios at different osmotic potentials was investigated. The plants were grown in outdoor solution culture tanks containing polyethylene glycol and/or NaCl as osmoticum with 1/2 strength Hoagland as the base nutrient solution. The mass of the root system for both wheat and sorghum was determined primarily by the osmotic potential. However, root elongation was controlled primarily by the Na/sup +/ concentration. Sorghum root elongation rates decreased with increasing Na/sup +/ while those for wheat increased. Sodium was not translocated out of the sorghum root system until a critical Na/sup +/ root saturation level of .6 moles/kg was obtained. The second experiment was designed to investigate the water, nutrient and growth responses of the second crop of wheat in a wheat-sorghum-wheat rotation to zonal saline-sodic conditions.

Devitt, D.A.

1983-01-01

258

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

NASA Astrophysics Data System (ADS)

We present measurements of the total elastic and resonant charge-exchange ion-atom collision rate coefficient kia of cold sodium (Na) with optically dark low-energy Na+ ions in a hybrid ion-neutral trap. To determine kia, we measured the trap loading and loss rates from both a Na magneto-optical trap (MOT) and a linear radio-frequency quadrupole Paul trap. We found the total rate coefficient to be 7.4 1.9 10-8 cm3/s for the type-I Na MOT immersed within an ?140 -K ion cloud and 1.10 0.25 10-7 cm3/s for the type-II Na MOT within an ?1070 -K ion cloud. Our measurements show excellent agreement with previously reported theoretical fully quantal ab initio calculations. In the process of determining the total rate coefficient, we demonstrate that a MOT can be used to probe an optically dark ion cloud's spatial distribution within a hybrid trap.

Goodman, D. S.; Wells, J. E.; Kwolek, J. M.; Blmel, R.; Narducci, F. A.; Smith, W. W.

2015-01-01

259

Performance of lime-BHA solidified plating sludge in the presence of Na2SiO3 and Na2CO3.  

PubMed

This research investigated the performance of lime-BHA (black rice husk ash) solidified plating sludge with 2 wt% NaO from Na(2)SiO(3) and Na(2)CO(3) at the level of 0, 30 and 50 wt%. The sludge was evaluated for strength development, leachability, solution chemistry and microstructure. The lime-BHA solidified plating sludge with Na(2)SiO(3) and Na(2)CO(3) had higher early strength when compared to the control. The addition of Na(2)SiO(3) and Na(2)CO(3) increased the OH(-) concentration and decreased the Ca(2+) and heavy metal ions in solution after the first minute. The XRD patterns showed that the addition of Na(2)SiO(3) resulted in the formation of calcium silicate hydrates, while the addition of Na(2)CO(3) resulted in CaCO(3). The heavy metals from the plating sludge, especially Zn, were immobilized in calcium zincate and calcium zinc silicate forms for the lime-BHA with and without Na(2)SiO(3) solidified wastes, while samples with Na(2)CO(3) contained Zn that was fixed in the form of CaZnCO(3). The cumulative leaching of Fe, Cr and Zn from the lime-BHA solidified plating sludge decreased significantly when activators were added, especially Na(2)CO(3). PMID:21549500

Piyapanuwat, Rungroj; Asavapisit, Suwimol

2011-09-01

260

Pancreatic ?-cell Na+ channels control global Ca2+ signaling and oxidative metabolism by inducing Na+ and Ca2+ responses that are propagated into mitochondria.  

PubMed

Communication between the plasma membrane and mitochondria is essential for initiating the Ca(2+) and metabolic signals required for secretion in ? cells. Although voltage-dependent Na(+) channels are abundantly expressed in ? cells and activated by glucose, their role in communicating with mitochondria is unresolved. Here, we combined fluorescent Na(+), Ca(2+), and ATP imaging, electrophysiological analysis with tetrodotoxin (TTX)-dependent block of the Na(+) channel, and molecular manipulation of mitochondrial Ca(2+) transporters to study the communication between Na(+) channels and mitochondria. We show that TTX inhibits glucose-dependent depolarization and blocks cytosolic Na(+) and Ca(2+) responses and their propagation into mitochondria. TTX-sensitive mitochondrial Ca(2+) influx was largely blocked by knockdown of the mitochondrial Ca(2+) uniporter (MCU) expression. Knockdown of the mitochondrial Na(+)/Ca(2+) exchanger (NCLX) and Na(+) dose response analysis demonstrated that NCLX mediates the mitochondrial Na(+) influx and is tuned to sense the TTX-sensitive cytosolic Na(+) responses. Finally, TTX blocked glucose-dependent mitochondrial Ca(2+) rise, mitochondrial metabolic activity, and ATP production. Our results show that communication of the Na(+) channels with mitochondria shape both global Ca(2+) and metabolism signals linked to insulin secretion in ? cells.- Nita, I. I., Hershfinkel, M., Kantor, C., Rutter, G. A., Lewis, E. C., Sekler, I. Pancreatic ?-cell Na(+) channels control global Ca(2+) signaling and oxidative metabolism by inducing Na(+) and Ca(2+) responses that are propagated into mitochondria. PMID:24719357

Nita, Iulia I; Hershfinkel, Michal; Kantor, Chase; Rutter, Guy A; Lewis, Eli C; Sekler, Israel

2014-08-01

261

Ability of multicellular salt glands in Tamarix species to secrete Na+ and K+ selectively.  

PubMed

The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands. Using a hydroponic culture system, the secretion and accumulation of Na(+) and K(+) in Tamarix ramosissima and T. laxa under different salt stresses (NaCl, KCl and NaCl+KCl) were studied. Additionally, the effects of salt gland inhibitors (orthovanadate, Ba(2+), ouabain, tetraethylammonium (TEA) and verapamil) on Na(+) and K(+) secretion and accumulation were examined. Treatment with NaCl (at 0-200 mmol L(-1) levels) significantly increased Na(+) secretion, whereas KCl treatment (at 0-200 mmol L(-1) levels) significantly increased K(+) secretion. The ratio of secretion to accumulation of Na(+) was higher than that of K(+). The changes in Na(+) and K(+) secretion differed after adding different ions into the single-salt solutions. Addition of NaCl to the KCl solution (at 100 mmol L(-1) level, respectively) led to a significant decrease in K(+) secretion rate, whereas addition of KCl to the NaCl solution (at 100 mmol L(-1) level, respectively) had little impact on the Na(+) secretion rate. These results indicated that Na+ secretion in Tamarix was highly selective. In addition, Na(+) secretion was significantly inhibited by orthovanadate, ouabain, TEA and verapamil, and K(+) secretion was significantly inhibited by ouabain, TEA and verapamil. The different impacts of orthovanadate on Na(+) and K(+) secretion might be the primary cause for the different Na(+) and K(+) secretion abilities of multicellular salt glands in Tamarix. PMID:21416329

Ma, Haiyan; Tian, Changyan; Feng, Gu; Yuan, Junfeng

2011-03-01

262

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

PubMed Central

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

de Lores Arnaiz, Georgina Rodrguez; Ordieres, Mara Graciela Lpez

2014-01-01

263

Branching ratios for the beta decay of Na-21  

E-print Network

relationship: R1 = N?? N?#4;? k, (1) where N?? is the number of 351-keV ? rays observed in coincidence with betas; N? is the number of (singles) betas observed; #4;? is the efficiency of the HPGe detector for 351-keV ? rays; and k is a factor (?1... ? rays ob- served in coincidence with positrons following the decay of 21Na. It includes about half of the total data collected. The peaks attributable to 21Na are marked with their energy in keV; the sum peak is identified by its components...

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

2006-01-01

264

Efficiency of the Modular Neutron Array (MoNA)  

SciTech Connect

The efficiency of the Modular Neutron Array (MoNA), located at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University, was measured and compared to simulations. The Coulomb dissociation of a 90 MeV/u beam of {sup 11}Be in a gold target was used to produce neutrons. The expected neutron production rate was calculated using the virtual photon method. The measured efficiency agrees with the efficiency calculated with GEANT simulations. The current configuration of MoNA has a 73% intrinsic detection efficiency for 90 MeV neutrons.

Peters, W. A. [Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, ML 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, ML 48824 (United States); Baumann, T. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, ML 48824 (United States); Christian, G. A.; Strongman, M. J. [Department of Physics and Astronomy, Michigan State University, East Lansing, ML 48824 (United States); Denby, D.; DeYoung, P. A.; Hall, C. C. [Department of Physics, Hope College, Holland, ML 49423 (Netherlands); Finck, J. E. [Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Frank, N. [Physics Department, Illinois Wesleyan University, Bloomington, LL 61701 (United States); Hinnefeld, J. [Department of Physics, Indiana University South Bend, South Bend, LN 46634 (United States); Schiller, A. [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Thoennessen, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, ML 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, ML 48824 (United States)

2009-03-10

265

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

Bonaiuto, V; Paoluzzi, G; Salamon, A; Salina, G; Santovetti, E; Sargeni, F; Scarf, F M

2012-01-01

266

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

V. Bonaiuto; A. Fucci; G. Paoluzzi; A. Salamon; G. Salina; E. Santovetti; F. Sargeni; F. M. Scarfi'

2012-01-16

267

The NA62 Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger  

E-print Network

The NA62 experiment at CERN SPS aims to measure the Branching Ratio of the very rare kaon decay K+ -> pi+ nu nubar collecting O(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K+ -> pi+ pi0 decay. To suppress this background an efficient photo veto system is foreseen. In the 1-10 mrad angular region the NA48 high performance liquid krypton electromagnetic calorimeter is used. The design, implementation and current status of the Liquid Krypton Electromagnetic Calorimeter Level 0 Trigger are presented.

Vincenzo Bonaiuto; Adolfo Fucci; Giovanni Paoluzzi; Andrea Salamon; Gaetano Salina; Emanuele Santovetti; Fausto Sargeni; Francesco M. Scarfi'

2012-01-18

268

Possible selective adsorption of enantiomers by Na-montmorillonite  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

269

MAKSIMALNA UBRZANJA NA SPRATOVIMA VIESPRATNIH ZGRADA Rezime  

Microsoft Academic Search

Za obezbe)enje sigurnost krutih nenose*ih komponenti u konstrukcijama zgrada vano je ta(no i jednostavno odrediti najve*a ubrzanja na spratovina gde se ove komponente nalaze, za odredjen seizmi(ki hazard. Nedavno predloeno pravilo, na bazi superpozicije karakteristi(nih funkcija konstrukcije, je dalje usavreno (ime se postie ta(nija ocena u slu(ajevima kad silno pomeranje sadri duge periode. Numeri(ke analize pokazuju da predloeno pravilo daje

Vinay K. Gupta; Manish Kumar; Dharmendra Kumar

270

Clean demarcation of cartilage tissue 23Na by inversion recovery.  

PubMed

Monitoring the sodium concentration in vivo using 23Na MRI can be an important tool for assessing the onset of tissue disorders. Practical clinical 23Na MRI methods furthermore often do not allow one to use sufficiently small voxel sizes such that only the tissue of interest is seen, but a large signal contamination can arise from sodium in synovial fluid. Here we demonstrate that applying an inversion recovery (IR) technique allows one to distinctly select either the cartilage-bound or the free sodium for visualization in an image. The results are validated both ex vivo and in vivo. PMID:18502158

Rong, Peng; Regatte, Ravinder R; Jerschow, Alexej

2008-08-01

271

Russian Scientific-Educational Project: Kazan-GeoNa-2017  

NASA Astrophysics Data System (ADS)

For the further successful development of educational and scientific - educational activity of the Russian Federation, the Republic Tatarstan, Kazan is offered the national project - the International Center of the Science and the Internet of Technologies. "GeoNa" (Geometry of Nature - "GeoNa" is developed - wisdom, enthusiasm, pride, grandeur), which includes a modern complex of conference halls (up to 4 thousand places), the Center the Internet of Technologies, 3D Planetarium - development of the Moon, PhysicsLand, an active museum of natural sciences, an oceanarium, training a complex Spheres of Knowledge, botanical and landscape oases.

Gusev, A.; Alibekova, N.

2012-09-01

272

Na+ and Li+ NASICON Superionic Conductors Thick Films  

Microsoft Academic Search

For microionic applications, superionic conductors have been elaborated in the form of thick films, using silk-screen printable powders. Na3Zr2Si2PO12, Na3.1Zr1.55Si2.3P0.7O11 and Li0.8Zr1.8Ta0.2(PO4)3 compositions are synthesized by a sol-gel process involving hydrolysis-polycondensation reactions of metal-organic alcoholic solutions. A thermal treatment (600C-800C) allows to obtain very fine particles (<1 mum) with the pure NASICON phase. Inks are prepared with these powders, an

H. Perthuis; G. Velasco; Ph. Colomban

1984-01-01

273

Crystallization patterns of membrane-bound (Na+ +K+)-ATPase.  

PubMed

Extensive formation of two-dimensional crystals of the proteins of the pure membrane-bound (Na+ +K+)-ATPase is induced during prolonged incubation with vanadate and magnesium. Some membrane crystals are formed in medium containing magnesium and phosphate. Computer-averaged images of the two-dimensional crystals show that the unit cell in vanadate-induced crystals contains a protomeric alpha beta-unit of the enzyme protein. In phosphate-induced crystals an (alpha beta) 2-unit occupies one unit cell suggesting the interactions between alpha beta-units can be of importance in the function of the Na+, K+ pump. PMID:6289891

Hebert, H; Jrgensen, P L; Skriver, E; Maunsbach, A B

1982-08-12

274

Glucocorticoid stimulation of ileal Na+ absorptive cell brush border Na+/H+ exchange and association with an increase in message for NHE-3, an epithelial Na+/H+ exchanger isoform.  

PubMed

Methylprednisolone stimulates rabbit ileal neutral NaCl absorption; and aminoglutethimide, which decreases glucocorticoid levels, decreases NaCl absorption. Studies were carried out to determine the mechanism of these effects and to determine which members of the gene family of mammalian Na+/H+ exchangers were involved. Rabbits were treated subcutaneously with methylprednisolone (40 mg daily for 24 or 72 h), aminoglutethimide (100 mg twice daily for 72 h), or saline as a control. Ileal brush border membranes were prepared by magnesium precipitation, and brush border Na+/H+ exchange was determined by 22Na+ uptake over 3-8 s. The 22Na+ uptake experiments were performed in the presence of a voltage clamp using either valinomycin/potassium or tetramethylammonium/nitrate to eliminate potential contributions by other electrogenic transport processes. Methylprednisolone treatment approximately doubled ileal brush border Na+/H+ exchange, whereas aminoglutethimide led to a 50% decrease in Na+/H+ exchange. These effects were specifically on Na+ uptake with an acid inside pH gradient, whereas diffusive Na+ uptake (no pH gradient), glucose-dependent Na+ uptake, and glucose and Na+ equilibrium volumes were not affected. To determine if the increase in Na+/H+ exchange was associated with an increase in message expression, mRNA levels were measured by ribonuclease protection assay. Methylprednisolone stimulated the NHE-3 mRNA level by 4-6-fold at 24 h, which remained increased at 72 h. In contrast, messages for NHE-1 and NHE-2 were not affected by methylprednisolone. In summary, 1) methylprednisolone stimulation of rabbit ileal Na+ absorption is due to stimulation of ileal villus cell brush border Na+/H+ exchange; 2) basal ileal brush border Na+/H+ exchange is dependent on glucocorticoid levels; and 3) an increase in NHE-3 message, but not in NHE-1 or NHE-2 message, correlates with the stimulation of ileal brush border Na+/H+ exchange. It is likely that NHE-3 is an Na+/H+ exchanger that is involved in ileal Na+ absorption. PMID:8380155

Yun, C H; Gurubhagavatula, S; Levine, S A; Montgomery, J L; Brant, S R; Cohen, M E; Cragoe, E J; Pouyssegur, J; Tse, C M; Donowitz, M

1993-01-01

275

Investigation of the thermonuclear 18Ne(?,p)21Na reaction rate via resonant elastic scattering of 21Na + p  

NASA Astrophysics Data System (ADS)

The 18Ne(?,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 2105 pps, with a purity of about 70% on target. The recoiled protons were measured at the center-of-mass scattering angles of ?c.m.?175.2?, 152.2?, and 150.5? by three sets of ?E-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 J? assignments and confirmed some tentative assignments made in previous work. The thermonuclear 18Ne(?,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(?,p)21Na rate significantly affects the peak nuclear energy generation rate, reaction fluxes, and onset temperature of this breakout reaction in these astrophysical phenomena.

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

276

Occlusion of ²²Na+ and ⁸⁶Rb+ in membrane-bound and soluble protomeric alpha beta-units of Na,K-ATPase  

Microsoft Academic Search

In this work, we examined occlusion of ²²Na+ and ⁸⁶Rb+ in membranous and detergent-solubilized Na,K-ATPase from outer renal medulla. Optimum conditions for occlusion of ²²Na+ were provided by formation of the phosphorylated complex from the beta,gamma-bidentate complex of chromium (III) with ATP (CrATP). Release of occluded cations occurred at equally slow rates in soluble and membrane-bound Na,K-ATPase. Values of ²²Na+

B. Vilsen; J. P. Andersen; J. Petersen; P. L. Jorgensen

1987-01-01

277

Etch Induction Time in CR-39 Detectors Etched in Na2CO3 Mixed NaOH Solution  

NASA Astrophysics Data System (ADS)

Six different solutions of 6M NaOH, containing different amounts of Na2CO3 at 70C were used for the revelation of latent damage trails in CR-39 plastic track detectors. These detectors were earlier exposed to fission fragments from 252Cf source for 30 min in vacuum and were then etched in the respective solutions for different etching time intervals of 5-20 min starting from 5min up to 160min. The etch induction time in each detector was obtained by extrapolating the intersection of resulting curves of track lengths and track diameters with the time axis.

N., Ali; Khan U., E.; K., Khan

2009-09-01

278

background Na+ conductance in pacemaking activity is unproven,  

E-print Network

background Na+ conductance in pacemaking activity is unproven, only the hasty would suggest that it is unlikely. Arrested pacemaker cells have membrane potentials of -35mY: some outward current must flow the membranes of arrested pacemaker cells whereas vagal stimulation does7. In beat- ing hearts vagal stimulation

Apkarian, A. Vania

279

Project ELaNa and NASA's CubeSat Initiative  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the NASA program to use expendable lift vehicles (ELVs) to launch nanosatellites for the purpose of enhancing educational research. The Education Launch of Nanosatellite (ELaNa) project, run out of the Launch Services Program is requesting proposals for CubeSat type payload to provide information that will aid or verify NASA Projects designs while providing higher educational research

Skrobot, Garrett Lee

2010-01-01

280

O pleno emprego na perspectiva da modernizao reflexiva  

Microsoft Academic Search

Resumo O pleno emprego foi o esteio para a segurana social na Primeira Modernidade. As polticas keynesianas implementadas a partir da crise de 1929 caminharam em direo composio de um Estado- nacional social. O prprio sucesso do capitalismo industrial provoca mudanas. O desenvolvimento tecnolgico, a crescente riqueza e a queda do muro de Berlim impulsionam a sociedade industrial para

Maria do Carmo; Cataldi Muterle

281

The putative mechanism of Na+ absorption in euryhaline  

E-print Network

The putative mechanism of Na+ absorption in euryhaline elasmobranchs exists in the gills December 2006 Abstract We recently cloned an NHE3 orthologue from the gills of the euryhaline Atlantic in the gills of the stenohaline marine spiny dogfish shark (Squalus acanthias). NHE3 immunoreactivity

Evans, David H.

282

Optimization of Automated Float Glass Lines Byungsoo Na, Shabbir Ahmed  

E-print Network

Optimization of Automated Float Glass Lines Byungsoo Na, Shabbir Ahmed , George Nemhauser and Joel flat glass products being manufactured on float glass lines. New technologies are allowing float glass our methods are currently being implemented at a major float glass manufacturer. Abstract In automated

Ahmed, Shabbir

283

Exploring Neutron-Rich Oxygen Isotopes with MoNA  

E-print Network

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

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

2007-01-01

284

Exploring Neutron-Rich Oxygen Isotopes with MoNA  

E-print Network

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

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

2007-08-20

285

Exploring Neutron-Rich Oxygen Isotopes with MoNA  

SciTech Connect

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

Frank, N.; Gade, A.; Peters, W. A.; Thoennessen, M. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Baumann, T.; Bazin, D.; Lecouey, J.-L.; Scheit, H.; Schiller, A. [National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States); Brown, J. [Department of Physics, Wabash College, Crawfordsville, IN 47933 (United States); DeYoung, P. A. [Department of Physics, Hope College, Holland, MI 49423 (United States); Finck, J. E. [Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Hinnefeld, J. [Department of Physics and Astronomy, Indiana University at South Bend, South Bend, IN 46634 (United States); Howes, R. [Department of Physics, Marquette University, Milwaukee, WI 53201 (United States); Luther, B. [Department of Physics, Concordia College, Moorhead, MN 56562 (United States)

2007-11-30

286

Regulation of Intracellular Cholesterol Distribution by Na/K-ATPase*  

E-print Network

Regulation of Intracellular Cholesterol Distribution by Na/K-ATPase* Received for publication/K-ATPase 1 subunit produces a parallel decrease in both caveolin-1 and cholesterol in light fractions of LLC redistribution of cholesterol from the plasma membrane to intracellular compartments in the knockdown cells

Brand, Paul H.

287

Multiple carbohydrate moieties on the Na+/H+ exchanger.  

PubMed Central

Affinity-purified antibodies against the C-terminal region of the Na+/H+ exchanger (NHE-1) were used to analyse the carbohydrate moiety of the protein. The Na+/H+ exchanger in human placental brush-border membranes has an apparent molecular mass of 105 kDa. Incubation of intact or detergent-solubilized membranes with glycopeptidase F removed the carbohydrate moiety and increased the apparent mobility of the exchanger. Digestion with endoglycosidase-F caused a similar change in mobility, but endoglycosidase-H had no effect, suggesting that the placental Na+/H+ exchanger is a glycoprotein of the biantennary complex type. Removal of the carbohydrate moiety with glycopeptidase F had no effect on the ability of the protein to promote the exchange of Na+ for H+, and had no detectable effect on the sensitivity of the exchanger to trypsin. Limited digestion with glycopeptidase F and neuraminidase indicated the presence of two intermediate forms between the fully glycosylated and the deglycosylated protein. This suggests the presence of at least two, and possibly three, N-linked carbohydrate moieties. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:8382044

Haworth, R S; Frhlich, O; Fliegel, L

1993-01-01

288

Altered erythrocyte Na-K pump in anorectic patients  

SciTech Connect

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

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

1985-07-01

289

Hydroxyl groups in zeolites CaNaA  

NASA Astrophysics Data System (ADS)

OH groups on shallow-bed-treated zeolites CaNaA were studied using diffuse reflectance infrared spectroscopy in the near-infrared region. For activation temperatures in the range 160-280C bridging OH groups were found. The bulk of OH groups, however, are AlOH on extra-framework aluminium.

Mix, H.; Pfeifer, H.; Staudte, B.

1988-05-01

290

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

291

Results from NA60 experiment at the CERN SPS  

SciTech Connect

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

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

2006-07-11

292

Thyroid Na /I Symporter MECHANISM, STOICHIOMETRY, AND SPECIFICITY*  

E-print Network

. It is now firmly established that active accumulation of io- dide (I ) by the thyroid gland epithelium membrane of the thyroid gland follicular cells. Io- dide transport into the thyroid gland has attractedThyroid Na /I Symporter MECHANISM, STOICHIOMETRY, AND SPECIFICITY* (Received for publication, May

Eskandari, Sepehr

293

Tecnologia de Agentes na Convergncia das Telecomunicaes com a Computao  

E-print Network

Tecnologia de Agentes na Convergência das Telecomunicações com a Computação Joaquim Croca Eng desafios considera-se o paradigma e a tecnologia dos agentes de software como uma aproximação adequada, com de recentes desenvolvimentos de tecnologias como o TINA-C, CORBA ou Web Services. Alguns

da Silva, Alberto Rodrigues

294

A reinveno da sexualidade masculina na paraplegia adquirida  

Microsoft Academic Search

RESUMO Neste trabalho a sexualidade masculina discutida a partir da condio de um homem com leso medular. Seu objetivo foi investigar o impacto da paraplegia adquirida na sexualidade masculina. Metodologicamente adotou-se uma aborda- gem qualitativa e coletou-se a histria de vida por meio de entrevistas. As princi- pais concluses apontam para um deslocamento das representaes da masculi- nidade associadas

Luiz Carlos Avelino da Silva; Paulo Albertini

2007-01-01

295

Elucidation of the Na+, K+-ATPase digitalis binding site.  

PubMed

Despite controversy over their use and the potential for toxic side effects, cardiac glycosides have remained an important clinical component for the treatment for congestive heart failure (CHF) and supraventricular arrhythmias since the effects of Digitalis purpurea were first described in 1785. While there is a wealth of information available with regard to the effects of these drugs on their pharmacological receptor, the Na(+), K(+)-ATPase, the exact molecular mechanism of digitalis binding and inhibition of the enzyme has remained elusive. In particular, the absence of structural knowledge about Na(+), K(+)-ATPase has thwarted the development of improved therapeutic agents with larger therapeutic indices via rational drug design approaches. Here, we propose a binding mode for digoxin and several analogues to the Na(+), K(+)-ATPase. A 3D-structural model of the extracellular loop regions of the catalytic alpha1-subunit of the digitalis-sensitive sheep Na(+), K(+)-ATPase was constructed from the crystal structure of an E(1)Ca(2+) conformation of the SERCA1a and a consensus orientation for digitalis binding was inferred from the in silico docking of a series of steroid-based cardiotonic compounds. Analyses of species-specific enzyme affinities for ouabain were also used to validate the model and, for the first time, propose a detailed model of the digitalis binding site. PMID:15886034

Keenan, Susan M; DeLisle, Robert K; Welsh, William J; Paula, Stefan; Ball, William J

2005-06-01

296

National Aeronautics and Space Administration NaNotechNology Roadmap  

E-print Network

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

Waliser, Duane E.

297

tudent naj bo na amerikem kolidu  

E-print Network

zabavo in da niso neusmiljeno tekmovalni (kar je precej redek pojav na najzahtevnejih 172 ~olah). Ker je bil to ?etrtek zve?er. jih je bila ve?ina zelo zaposlenih z nalogami in projekti - povedali so mu, da se zabave dogajajo ?ez vikend - a nekaj jih...

Pirnat-Greenberg, Marta

2007-01-01

298

Synthesis of Na-zeolites from fly ash  

Microsoft Academic Search

The present study focuses on the synthesis of zeolites after fly ash activation, the major objectives being: (a) to study the activation processes; (b) to elucidate the activation conditions for maximum synthesis efficiency; (c) to optimize the conditions for the monomineral synthesis; and (d) to test synthesis efficiencies for different fly ash types. Fly ash was activated by NaOH and

Xavier Querol; Felici Plana; Andrs Alastuey; Angel Lpez-Soler

1997-01-01

299

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

300

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

PubMed Central

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

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

2013-01-01

301

Planificacin de la transicin a la atencin en la etapa final de la vida para los pacientes con cncer en estadio avanzado (PDQ)  

Cancer.gov

Resumen de informacin revisada por expertos sobre la preparacin necesaria por parte de los proveedores de atencin de la salud, los pacientes y sus familas para la transicin a la etapa final de la vida en los casos de cncer en estadio avanzado.

302

Planificacin de la transicin a la atencin en la etapa final de la vida para los pacientes de cncer en estadio avanzado (PDQ)  

Cancer.gov

Resumen de informacin revisada por expertos sobre la preparacin necesaria por parte de los proveedores de atencin de la salud, los pacientes y sus familas para la transicin a la etapa final de la vida en los casos de cncer en estadio avanzado.

303

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

PubMed

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

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

2014-12-01

304

Na+-independent phosphate transport in Caco2BBE cells.  

PubMed

Pi transport in epithelia has both Na(+)-dependent and Na(+)-independent components, but so far only Na(+)-dependent transporters have been characterized in detail and molecularly identified. Consequently, in the present study, we initiated the characterization and analysis of intestinal Na(+)-independent Pi transport using an in vitro model, Caco2BBE cells. Only Na(+)-independent Pi uptake was observed in these cells, and Pi uptake was dramatically increased when cells were incubated in high-Pi DMEM (4 mM) from 1 day to several days. No response to low-Pi medium was observed. The increased Pi transport was mainly caused by Vmax changes, and it was prevented by actinomycin D and cycloheximide. Pi transport in cells grown in 1 mM Pi (basal DMEM) decreased at pH > 7.5, and it was inhibited with proton ionophores. Pi transport in cells incubated with 4 mM Pi increased with alkaline pH, suggesting a preference for divalent phosphate. Pi uptake in cells in 1 mM Pi was completely inhibited only by Pi and partially inhibited by phosphonoformate, oxalate, DIDS, SITS, SO4 (2-), HCO3 (-), and arsenate. This inhibition pattern suggests that more than one Pi transporter is active in cells maintained with 1 mM Pi. Phosphate transport from cells maintained at 4 mM Pi was only partially inhibited by phosphonoformate, oxalate, and arsenate. Attempts to identify the responsible transporters showed that multifunctional anion exchangers of the Slc26 family as well as members of Slc17, Slc20, and Slc37 and the Pi exporter xenotropic and polytropic retrovirus receptor 1 are not involved. PMID:25298422

Candeal, Eduardo; Caldas, Yupanqui A; Guilln, Natalia; Levi, Moshe; Sorribas, Vctor

2014-12-15

305

Characterization of Na+K+-ATPase in bovine sperm.  

PubMed

Existing as a ubiquitous transmembrane protein, Na(+)K(+)-ATPase affects sperm fertility and capacitation through ion transport and a recently identified signaling function. Functional Na(+)K(+)-ATPase is a dimer of ? and ? subunits, each with isoforms (four and three, respectively). Since specific isoform pairings and locations may influence or indicate function, the objective of this study was to identify and localize subunits of Na(+)K(+)-ATPase in fresh bull sperm by immunoblotting and immunocytochemistry using antibodies against ?1 and 3, and all ? isoforms. Relative quantity of Na(+)K(+)-ATPase in head plasma membranes (HPM's) from sperm of different bulls was determined by densitometry of immunoblot bands, and compared to bovine kidney. Sperm and kidney specifically bound all antibodies at kDa equivalent to commercial controls, and to additional lower kDa bands in HPM. Immunofluorescence of intact sperm confirmed that all isoforms were present in the head region of sperm and that ?3 was also uniformly distributed post-equatorially. Permeabilization exposing internal membranes typically resulted in an increase in fluorescence, indicating that some antibody binding sites were present on the inner surface of the HPM or the acrosomal membrane. Deglycosylation of ?1 reduced the kDa of bands in sperm, rat brain and kidney, with the kDa of the deglycosylated bands differing among tissues. Two-dimensional blots of ?1 revealed three distinct spots. Based on the unique quantity, location and structure Na(+)K(+)-ATPase subunits in sperm, we inferred that this protein has unique functions in sperm. PMID:22284223

Hickey, Katie D; Buhr, Mary M

2012-04-15

306

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

NASA Technical Reports Server (NTRS)

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

Sprague, A.

1994-01-01

307

Aldosterone augments Na+-induced reduction of cardiac norepinephrine reuptake.  

PubMed

Impairment of the cardiac norepinephrine (NE) reuptake by the neuronal NE transporter contributes to enhanced cardiac NE net release in congestive heart failure. Elevated plasma levels of aldosterone (AL) promote sympathetic overstimulation in failing hearts by unclear mechanisms. Our aim was to evaluate if elevated AL and/or alterations in Na(+) intake regulate cardiac NE reuptake. To test the effects of AL and Na(+) on cardiac NE reuptake, Wistar rats were fed a normal-salt (NS) diet (0.2% NaCl), a low-salt (LS) diet (0.015% NaCl), or a high-salt (HS) diet (8% NaCl). Another group of animals received AL infusion alone (0.75 ?g/h) or AL infusion plus HS diet. Specific cardiac [(3)H]NE uptake via the NE transporter in a Langendorff preparation and AL plasma levels were measured at different time points between 5 and 42 days of treatment. To compare these findings from healthy animals with a disease model, Dahl salt-sensitive rats were investigated as a model of congestive heart failure with endogenously elevated AL. In summary, neither exogenous nor endogenous elevations of AL alone were sufficient to reduce cardiac NE reuptake. Only the HS diet induced a reduction of NE reuptake by 26%; additional infusion of AL augmented this effect to a further reduction of NE reuptake by 36%. In concordance, Dahl salt-sensitive rats treated with a HS diet displayed elevated AL and a marked reduction of NE reuptake. We conclude that exogenous or endogenous AL elevations alone do not reduce cardiac NE reuptake, but AL serves as an additional factor that negatively regulates cardiac NE reuptake in concert with HS intake. PMID:25128164

Kreusser, Michael M; Lehmann, Lorenz H; Riffel, Johannes H; Haass, Markus; Maser-Gluth, Christiane; Backs, Johannes; Katus, Hugo A; Buss, Sebastian J

2014-10-15

308

Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the  

E-print Network

within a longitudinal magnetic field B between two polarizers. The difference is a quarter-wave plate and then followed by polarization analysis with a quarter-wave plate and a polarized beam splitter. The static. © 2009 Optical Society of America OCIS codes: 280.3640, 300.6210, 010.3640. Resonance fluorescence Na

Chu, Xinzhao

309

Na-O Anticorrelation and Horizontal Branches. V. The Na-O anticorrelation in NGC 6441 from Giraffe spectra  

E-print Network

We present an analysis of FLAMES-Giraffe spectra for several bright giants in NGC 6441, to investigate the presence and extent of the Na-O anticorrelation in this anomalous globular cluster. The field of NGC 6441 is very crowded, with severe contamination by foreground (mainly bulge) field stars. Appropriate membership criteria were devised to identify a group of 25 likely cluster members among the about 130 stars observed. Combined with the UVES data obtained with the same observations, high dispersion abundance analyses are now available for a total of 30 stars in NGC 6441, 29 of them having data for both O and Na. The spectra were analyzed by a standard line analysis procedure; care was taken to minimize the impact of the differential interstellar reddening throughout the cluster, and to extract reliable information from crowded, and moderately high S/N (30-70), moderately high resolution (R ~ 23,000) spectra. NGC 6441 is very metal-rich ([Fe/H]=$-0.34\\pm 0.02\\pm0.04$ dex). There is no clear sign of star-to-star scatter in the Fe-peak elements. The alpha-elements Mg, Si, Ca, and Ti are overabundant by rather large factors, suggesting that the cluster formed from material enriched by massive core collapse SNe. The O-Na anticorrelation is well defined, with about 1/4 of the stars being Na-rich and O-poor. One of the stars is a Ba-rich and moderately C-rich star. The distribution of [Na/O] ratios among RGB stars in NGC 6441 appears similar to the distribution of colors of stars along the horizontal branch. The fraction of Na-poor, O-rich stars found in NGC 6441 agrees well with that of stars on the red horizontal branch of this cluster (in both cases about 80%), with a sloping distribution toward lower values of [O/Na] (among RGB stars and bluer colors (among HB stars).

R. G. Gratton; S. Lucatello; A. Bragaglia; E. Carretta; S. Cassisi; Y. Momany; E. Pancino; E. Valenti; V. Caloi; R. Claudi; F. D'Antona; S. Desidera; P. Fran{}ois; G. James; S. Moehler; S. Ortolani; L. Pasquini; G. Piotto; A. Recio-Blanco

2007-01-08

310

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

311

Investigation of Sodium Distribution in Phosphate Glasses Using Spin-Echo {sup 23}Na NMR  

SciTech Connect

The spatial arrangement of sodium cations for a series of sodium phosphate glasses, xNa{sub 2}O(100-x)P{sub 2}O{sub 5} (x<55), were investigated using {sup 23}Na spin-echo NMR spectroscopy. The spin-echo decay rate is a function of the Na-Na homonuclear dipolar coupling and is related to the spatial proximity of neighboring Na nuclei. The spin-echo decay rate in these sodium phosphate glasses increases non-linearly with higher sodium number density, and thus provides a measure of the Na-Na extended range order. The results of these {sup 23}Na NMR experiments are discussed within the context of several structural models, including a decimated crystal lattice model, cubic dilation lattice model, a hard sphere (HS) random distribution model and a pair-wise cluster hard sphere model. While the experimental {sup 23}Na spin-echo M{sub 2} are described adequately by both the decimated lattice and the random HS model, it is demonstrated that the slight non-linear behavior of M{sub 2} as a function of sodium number density is more correctly described by the random distribution in the HS model. At low sodium number densities the experimental M{sub 2} is inconsistent with models incorporating Na-Na clustering. The ability to distinguish between Na-Na clusters and non-clustered distributions becomes more difficult at higher sodium concentrations.

ALAM, TODD M.; BOYLE, TIMOTHY J.; BROW, RICHARD K.; CLICK, CAROL C.; CONZONE, SAM; McLAUGHLIN, JAY; ZWANZIGER, JOE

1999-09-16

312

The rat Na+-sulfate cotransporter rNaS2: functional characterization, tissue distribution, and gene (slc13a4) structure.  

PubMed

Inorganic sulfate is essential for numerous functions in mammalian physiology. In the present study, we characterized the functional properties of the rat Na+-sulfate cotransporter NaS2 (rNaS2), determined its tissue distribution, and identified its gene (slc13a4) structure. Expression of rNaS2 protein in Xenopus oocytes led to a Na+-dependent transport of sulfate that was inhibited by phosphate, thiosulfate, tungstate, selenate, oxalate, and molybdate, but not by citrate, succinate, or DIDS. Transport kinetics of rNaS2 determined a K(M) for sulfate of 1.26 mM. Na+ kinetics determined a Hill coefficient of n=3.0+/-0.7, suggesting a Na+:SO4 (2-) stoichiometry of 3:1. rNaS2 mRNA was highly expressed in placenta, with lower levels found in the brain and liver. slc13a4 maps to rat chromosome 4 and contains 17 exons, spanning over 46 kb in length. This gene produces two alternatively spliced transcripts, of which the transcript lacking exon 2 is the most abundant form. Its 5' flanking region contains CAAT- and GC-box motifs and a number of putative transcription factor binding sites, including GATA-1, SP1, and AP-2 consensus sequences. This is the first study to characterize rNaS2 transport kinetics, define its tissue distribution, and resolve its gene (slc13a4) structure and 5' flanking region. PMID:15889308

Dawson, Paul A; Pirlo, Katrina J; Steane, Sarah E; Nguyen, Kim A; Kunzelmann, Karl; Chien, Yu Ju; Markovich, Daniel

2005-07-01

313

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

PubMed

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

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

2014-03-01

314

Functional characteristics of NaS2, a placenta-specific Na+-coupled transporter for sulfate and oxyanions of the micronutrients selenium and chromium.  

PubMed

NaS2 is a Na+-coupled transporter for sulfate that belongs to the SLC13 gene family. This transporter was originally cloned from high endothelial venule endothelial cells, but nothing is known about the functional characteristics of this transporter except that it transports sulfate in a Na+-coupled manner. Northern blot analysis indicates that NaS2 is expressed most robustly in placenta. In the present study, we cloned NaS2 from rat placenta and characterized its transport function in detail using the Xenopus laevis oocyte expression system. Rat NaS2 consists of 629 amino acids and is highly similar to human NaS2. In situ hybridization studies with mouse placental sections show that NaS2 transcripts are expressed primarily in trophoblasts of the labyrinth zone. The expression of the transporter is confirmed in primary cultures of trophoblasts isolated from human placenta. When expressed in X. laevis oocytes, rat NaS2 mediates Na+-coupled transport of sulfate. The transport of sulfate is inhibited by oxyanions of selenium, chromium, arsenic, molybdenum, and phosphorous, suggesting that the transporter may mediate the transport of these oxyanions in addition to sulfate. The Kt for sulfate is 153+/-30 microM and the Na+:sulfate stoichiometry is 3:1. The transport process is electrogenic as evidenced from the inhibition of the uptake process by K+-induced depolarization. We conclude that NaS2 is a placenta-specific Na+-coupled, electrogenic, transporter for sulfate expressed in trophoblasts and that it is also responsible for the transport of oxyanions of the micronutrients selenium and chromium. PMID:16129486

Miyauchi, S; Srinivas, S R; Fei, Y-J; Gopal, E; Umapathy, N S; Wang, H; Conway, S J; Ganapathy, V; Prasad, P D

2006-01-01

315

Fusion of Na-ASP-2 with human immunoglobulin Fc? abrogates histamine release from basophils sensitized with anti-Na-ASP-2 IgE.  

PubMed

Na-ASP-2 is a major protein secreted by infective third-stage larvae (L3) of the human hookworm Necator americanus upon host entry. It was chosen as a lead vaccine candidate for its ability to elicit protective immune responses. However, clinical development of this antigen as a recombinant vaccine was halted because it caused allergic reactions among some of human volunteers previously infected with N.americanus. To prevent IgE-mediated allergic reactions induced by Na-ASP-2 but keep its immunogenicity as a vaccine antigen, we designed and tested a genetically engineered fusion protein, Fc?/Na-ASP-2, composed of full-length Na-ASP-2 and truncated human IgG Fc?1 that targets the negative signalling receptor Fc?RIIb expressed on pro-allergic cells. The chimeric recombinant Fc?/Na-ASP-2 protein was expressed in Pichia pastoris and shared the similar antigenicity as native Na-ASP-2. Compared to Na-ASP-2, the chimeric fusion protein efficiently reduced the release of histamine in human basophils sensitized with anti-Na-ASP-2 IgE obtained from individuals living in a hookworm-endemic area. In dogs infected with canine hookworm, Fc?/Na-ASP-2 resulted in significantly reduced immediate-type skin reactivity when injected intradermally compared with Na-ASP-2. Hamsters vaccinated with Fc?/Na-ASP-2 formulated with Alhydrogel() produced specific IgG that recognized Na-ASP-2 and elicited similar protection level against N.americanus L3 challenge as native Na-ASP-2. PMID:22651670

Zhan, Bin; Santiago, H; Keegan, B; Gillespie, P; Xue, J; Bethony, J; de Oliveira, L M; Jiang, D; Diemert, D; Xiao, S-H; Jones, K; Feng, X; Hotez, P J; Bottazzi, M E

2012-01-01

316

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)

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.

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

1995-01-01

317

Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles  

EPA Science Inventory

Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

318

Controlling Na diffusion by rational design of Si-based layered architectures.  

PubMed

By means of density functional theory, we systematically investigate the insertion and diffusion of Na and Li in layered Si materials (polysilane and H-passivated silicene), in comparison with bulk Si. It is found that Na binding and mobility can be significantly facilitated in layered Si structures. In contrast to the Si bulk, where Na insertion is energetically unfavorable, Na storage can be achieved in polysilane and silicene. The energy barrier for Na diffusion is reduced from 1.06 eV in the Si bulk to 0.41 eV in polysilane. The improvements in binding energetics and in the activation energy for Na diffusion are attributed to the large surface area and available free volume for the large Na cation. Based on these results, we suggest that polysilane may be a promising anode material for Na-ion and Li-ion batteries with high charge-discharge rates. PMID:24452014

Kulish, Vadym V; Malyi, Oleksandr I; Ng, Man-Fai; Chen, Zhong; Manzhos, Sergei; Wu, Ping

2014-03-01

319

Efeito preventivo da fisioterapia na reduo da incidncia de quedas em pacientes com Doena de Alzheimer Preventive effect of the physical therapy to minimize the occurrence of falls in patients with Alzheimer's Disease  

Microsoft Academic Search

SUMMARY The purpose of this review is to provide better understanding of the preventive effect resulted by the Physical Therapy in- tervention to minimize the occurrence of falls in patients with Alzheimer Disease. The Alzheimer Disease is the main cause of dementia between aged people. In recent years it has been showing an increase in the number of patients proportional

Tetsad CB Piermartiri; Naara Camboim Bezerra; Alexandre Ademar Hoeller

320

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

PubMed Central

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

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

2010-01-01

321

Competition between Na + and Li + for Unsealed and Cytoskeleton-Depleted Human Red Blood Cell Membrane: A 23Na Multiple Quantum Filtered and 7Li NMR Relaxation Study  

NASA Astrophysics Data System (ADS)

Evidence for competition between Li+ and Na+ for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li+ upon the 23Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na+-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed quenching effect of Li+ on the 23Na TQF and DQF signal intensity probed Li+/Na+ competition for isotropic binding sites only. Membrane cytoskeleton depletion significantly decreased the isotropic signal intensity, strongly affecting the binding of Na+ to isotropic membrane sites, but had no effect on Li+/Na+ competition for those sites. Through the observed 23Na DQF NMR spectra, which allow probing of both isotropic and anisotropic Na+ motion, we found anisotropic membrane binding sites for Na+ when the total ionic strength was higher than 40 mM. This is a consequence of ionic strength effects on the conformation of the cytoskeleton, in particular on the dimer-tetramer equilibrium of spectrin. The determinant involvement of the cytoskeleton in the anisotropy of Na+ motion at the membrane surface was demonstrated by the isotropy of the DQF spectra of csdRBC membranes even at high ionic strength. Li+ addition initially quenched the isotropic signal the most, indicating preferential Li+/Na+ competition for the isotropic membrane sites. High ionic strength also increased the intensity of the anisotropic signal, due to its effect on the restructuring of the membrane cytoskeleton. Further Li+ addition competed with Na+ for those sites, quenching the anisotropic signal. 7Li T1 relaxation data for Li+-containing suspensions of unsealed and csdRBC membranes, in the absence and presence of Na+ at low ionic strength, showed that cytoskeleton depletion does not affect the affinity of Na+ for the RBC membrane, but increases the affinity of Li+ by 50%. This clearly indicates that cytoskeleton depletion favors Li+ relative to Na+ binding, and thus Li+/Na+ competition for its isotropic sites. Thus, this relaxation technique proves to be very sensitive to alkali metal binding to the membrane, detecting a more pronounced steric hindrance effect of the cytoskeleton network to binding of the larger hydrated Li+ ion to the membrane phosphate groups.

Srinivasan, Chandra; Minadeo, Nicole; Toon, Jason; Graham, Daniel; Mota de Freitas, Duarte; Geraldes, Carlos F. G. C.

1999-09-01

322

Molecular Na-channel excitability from statistical physics  

NASA Astrophysics Data System (ADS)

The excitable properties of the neural cell membrane is the driving mechanism of the neural pulses. Coordinated ionic fluxes across Na and K channels are the devices responsible of this function. Here we present a simple microscopic physical scenario which accounts for this phenomenology. The main elements are ions and channel doors that obey the standard formulation of statistical physics (overdamped Langevin equations) with appropriate nonlinear interacting potentials. From these equations we obtain the ionic flux and the dynamics of the membrane potential. We show that the excitable properties of the membrane are present in a single and simple Na channel. From this framework, additional microscopic information can be obtained, such as statistics of single-channels dynamics or the energetics of action potential events.

Ramrez-Piscina, L.; Sancho, J. M.

2014-12-01

323

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

SciTech Connect

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

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

2009-03-31

324

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

PubMed Central

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

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

1999-01-01

325

[Effect of NaOH-treatment on dry-thermophilic anaerobic digestion of Spartina alterniflora].  

PubMed

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. PMID:21922846

Chen, Guang-Yin; Zheng, Zheng; Chang, Zhi-Zhou; Ye, Xiao-Mei; Luo, Yan

2011-07-01

326

Electrostatic K-Feldspar\\/Na-Feldspar and Feldspar\\/Quartz Separation: Influence of Feldspar Composition  

Microsoft Academic Search

This paper aims at contributing to the possibility of electrically separating K-feldspar\\/Na-feldspar and quartz\\/feldspar, investigating the behaviour of mixtures composed of K-feldspar, Na-feldspar and quartz concentrates. The findings highlight the importance of preheating the material and of interparticle contact. Tests conducted on binary mixtures of K-feldspar\\/Na-feldspar, K-feldspar\\/quartz and Na-feldspar\\/quartz showed that it is possible to achieve satisfactory results in the

R. Peretti; A. Serci; A. Zucca

2011-01-01

327

Electrostatic K-Feldspar\\/Na-Feldspar and Feldspar\\/Quartz Separation: Influence of Feldspar Composition  

Microsoft Academic Search

This article aims at contributing to the possibility of electrically separating K-feldspar\\/Na-feldspar and quartz\\/feldspar, investigating the behavior of mixtures composed of K-feldspar, Na-feldspar, and quartz concentrates. The findings highlight the importance of preheating the material and of interparticle contact. Tests conducted on binary mixtures of K-feldspar\\/Na-feldspar, K-feldspar\\/quartz, and Na-feldspar\\/quartz showed that it is possible to achieve satisfactory results in the

R. Peretti; A. Serci; A. Zucca

2012-01-01

328

Atomic structure of a Na+- and K+-conducting channel  

Microsoft Academic Search

Ion selectivity is one of the basic properties that define an ion channel. Most tetrameric cation channels, which include the K+, Ca2+, Na+ and cyclic nucleotide-gated channels, probably share a similar overall architecture in their ion-conduction pore, but the structural details that determine ion selection are different. Although K+ channel selectivity has been well studied from a structural perspective, little

Ning Shi; Sheng Ye; Amer Alam; Liping Chen; Youxing Jiang

2006-01-01

329

Redetermination of durangite, NaAl(AsO4)F  

PubMed Central

The crystal structure of durangite, ideally NaAl(AsO4)F (chemical name sodium aluminium arsenate fluoride), has been determined previously [Kokkoros (1938). Z. Kristallogr. 99, 3849] using Weissenberg film data without reporting displacement parameters of atoms or a reliability factor. This study reports the redetermination of the structure of durangite using single-crystal X-ray diffraction data from a natural sample with composition (Na0.95Li0.05)(Al0.91Fe3+ 0.07Mn3+ 0.02)(AsO4)(F0.73(OH)0.27) from the type locality, the Barranca mine, Coneto de Comonfort, Durango, Mexico. Durangite is isostructural with minerals of the titanite group in the space group C2/c. Its structure is characterized by kinked chains of corner-sharing AlO4F2 octahedra parallel to the c axis. These chains are cross-linked by isolated AsO4 tetrahedra, forming a three-dimensional framework. The Na+ cation (site symmetry 2) occupies the interstitial sites and is coordinated by one F? and six O2? anions. The AlO4F2 octahedron has symmetry -1; it is flattened, with the AlF bond length [1.8457?(4)?] shorter than the AlO bond lengths [1.8913?(8) and 1.9002?(9)?]. Examination of the Raman spectra for arsenate minerals in the titanite group reveals that the position of the band originating from the AsO symmetric stretching vibrations shifts to lower wavenumbers from durangite, maxwellite [ideally NaFe(AsO4)F], to tilasite [CaMg(AsO4)F]. PMID:23284315

Downs, Gordon W.; Yang, Betty N.; Thompson, Richard M.; Wenz, Michelle D.; Andrade, Marcelo B.

2012-01-01

330

Recent results from NA61/SHINE at the CERN SPS  

NASA Astrophysics Data System (ADS)

This contribution is devoted to looking at the NA61/SHINE experiment [1] through the prism of the needs of neutrino oscillation experiments. The new preliminary results on hadron production measurements from p+C (thin target - 0.04 ?I) interactions at 31 GeV/c from 2009 data are presented. These results are crucial for the precise determination of background contamination in the neutrino flux of the Tokai to Kamioka (T2K) experiment at J-PARC [2].

Palczewski, Tomasz Jan

2014-11-01

331

One-loop integrals with XLOOPS-GiNaC  

E-print Network

We present a new algorithm for the reduction of one-loop tensor Feynman integrals within the framework of the XLOOPS project, covering both mathematical and programming aspects. The new algorithm supplies a clean way to reduce the one-loop one-, two- and three-point Feynman integrals with arbitrary tensor rank and powers of the propagators to a basis of simple integrals. We also present a new method of coding XLOOPS in C++ using the GiNaC library.

C. Bauer; H. S. Do

2001-05-30

332

Time-dependent MOS breakdown. [of Na contaminated capacitors  

NASA Technical Reports Server (NTRS)

A general model for time-dependent breakdown in metal-oxide-silicon (MOS) structures is developed and related to experimental measurements on samples deliberately contaminated with Na. A statistical method is used for measuring the breakdown probability as a function of log time and applied field. It is shown that three time regions of breakdown can be explained respectively in terms of silicon surface defects, ion emission from the metal interface, and lateral ion diffusion at the silicon interface.

Li, S. P.; Bates, E. T.; Maserjian, J.

1976-01-01

333

Tissue kallikrein activation of the epithelial Na channel  

PubMed Central

Epithelial Na Channels (ENaC) are responsible for the apical entry of Na+ in a number of different epithelia including the renal connecting tubule and cortical collecting duct. Proteolytic cleavage of ?-ENaC by serine proteases, including trypsin, furin, elastase, and prostasin, has been shown to increase channel activity. Here, we investigate the ability of another serine protease, tissue kallikrein, to regulate ENaC. We show that excretion of tissue kallikrein, which is secreted into the lumen of the connecting tubule, is stimulated following 5 days of a high-K+ or low-Na+ diet in rats. Urinary proteins reconstituted in a low-Na buffer activated amiloride-sensitive currents (INa) in ENaC-expressing oocytes, suggesting an endogenous urinary protease can activate ENaC. We next tested whether tissue kallikrein can directly cleave and activate ENaC. When rat ENaC-expressing oocytes were exposed to purified tissue kallikrein from rat urine (RTK), ENaC currents increased threefold in both the presence and absence of a soybean trypsin inhibitor (SBTI). RTK and trypsin both decreased the apparent molecular mass of cleaved cell-surface ?-ENaC, while immunodepleted RTK produced no shift in apparent molecular mass, demonstrating the specificity of the tissue kallikrein. A decreased effect of RTK on Xenopus ENaC, which has variations in the putative prostasin cleavage sites in ?-ENaC, suggests these sites are important in RTK activation of ENaC. Mutating the prostasin site in mouse ?-ENaC (?RKRK186QQQQ) abolished ENaC activation and cleavage by RTK while wild-type mouse ENaC was activated and cleaved similar to that of the rat. We conclude that tissue kallikrein can be a physiologically relevant regulator of ENaC activity. PMID:22622459

Patel, Ankit B.; Chao, Julie

2012-01-01

334

Reaction of graphite fluoride with NaOHKOH eutectic  

Microsoft Academic Search

Graphite fluoride has been generally considered chemically inert against strong alkalis under ambient conditions. In the present study we demonstrate that treatment of graphite fluoride with eutectic NaOHKOH mixture at 250C induces dramatic structural and textural changes in the solid as evidenced by XRD, FT-IR, Raman, UVvis absorption and fluorescence and microscopy techniques (TEM, AFM). The reaction proceeds in the

Athanasios B. Bourlinos; Vasilios Georgakilas; Radek Zboril; Dalibor Jancik; Michael A. Karakassides; Andreas Stassinopoulos; Demetrios Anglos; Emmanuel P. Giannelis

2008-01-01

335

Cosmogenic radionuclide production in NaI(Tl) crystals  

E-print Network

The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detection of dark matter since the first nineties of the last century, very few data about cosmogenic isotopes production rates have been published up to date. In this work we present data from two 12.5 kg NaI(Tl) detectors, developed in the frame of the ANAIS project, which were installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays. The very fast start of data taking allowed to identify and quantify isotopes with half-lives of the order of tens of days. Initial activities underground have been measured and then production rates at sea level have been estimated following the history of detectors; values of about a few tens of nuclei per kg and day for Te isotopes and 22Na and of a few hundreds for I isotopes have been found. These are the first direct estimates of production rates of cosmogenic nuclides in NaI crystals. A comparison of the so deduced rates with calculations using typical cosmic neutron flux at sea level and a carefully selected description of excitation functions will be also presented together with an estimate of the corresponding contribution to the background at low and high energies, which can be relevant for experiments aiming at rare events searches.

J. Amar; S. Cebrin; C. Cuesta; E. Garca; C. Ginestra; M. Martnez; M. A. Olivn; Y. Ortigoza; A. Ortiz de Solrzano; C. Pobes; J. Puimedn; M. L. Sarsa; J. A. Villar; P. Villar

2015-01-16

336

Cosmogenic radionuclide production in NaI(Tl) crystals  

NASA Astrophysics Data System (ADS)

The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detection of dark matter since the first nineties of the last century, very few data about cosmogenic isotopes production rates have been published up to date. In this work we present data from two 12.5 kg NaI(Tl) detectors, developed in the frame of the ANAIS project, which were installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays. The very fast start of data taking allowed to identify and quantify isotopes with half-lives of the order of tens of days. Initial activities underground have been measured and then production rates at sea level have been estimated following the history of detectors; values of about a few tens of nuclei per kg and day for Te isotopes and 22Na and of a few hundreds for I isotopes have been found. These are the first direct estimates of production rates of cosmogenic nuclides in NaI crystals. A comparison of the so deduced rates with calculations using typical cosmic neutron flux at sea level and a carefully selected description of excitation functions will be also presented together with an estimate of the corresponding contribution to the background at low and high energies, which can be relevant for experiments aiming at rare events searches.

Amar, J.; Cebrin, S.; Cuesta, C.; Garca, E.; Ginestra, C.; Martnez, M.; Olivn, M. A.; Ortigoza, Y.; Ortiz de Solrzano, A.; Pobes, C.; Puimedn, J.; Sarsa, M. L.; Villar, J. A.; Villar, P.

2015-02-01

337

An analysis of Na + currents in rat olfactory receptor neurons  

Microsoft Academic Search

Na+ currents were observed in acutely-dissociated adult rat olfactory receptor neurons using the whole-cell recording techniques. The threshold for current activation was near -70mV and currents were fully activated by -10 mV (midpoint: -45 mV). Steady-state inactivation was complete at potentials more positive than -70mV and half complete at -110mV (2+ to the external solution was required to completely block

Sundran Rajendra; Joseph W. Lynch; Peter H. Barry

1992-01-01

338

Two-frequency lidar technique for mesospheric Na temperature measurements  

Microsoft Academic Search

The authors describe a new two-frequency lidar for measuring Na temperature profiles that uses a stabilized cw single-mode dye laser oscillator (rms frequency jitter < 1 MHz) followed by a pulsed-dye power amplifier (140 MHz FWHM linewidth) which is pumped by an injection-locked Nd:YAG laser. The laser oscillator is tuned to the two operating frequencies by observing the Doppler-free structure

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

1990-01-01

339

Caracterizao das instalaes avcolas na Mesorregio do Agreste Paraibano  

Microsoft Academic Search

RESUMO: Nos ltimos anos, as instalaes destinadas produo avcola no Brasil tm-se destacado pelo aumento da densidade de criao que visa a otimizar mo-de-obra, equipamentos, transporte, assistncia tcnica e, sobretudo, instalaes. O objetivo deste trabalho foi realizar pesquisa sobre as principais caractersticas tipolgicas dos avirios existentes na mesorregio do Agreste do Estado da Paraba. Observou-se que os avirios so

Dermeval A. Furtado; Ilda F. F. Tinoco; Jos W. B. do Nascimento; Antonio F. Leal; Marluce A. Azevedo

2005-01-01

340

UTILIZAO DA TECNOLOGIA WIMAX NA PREVENO DE Marlia Curado1*  

E-print Network

UTILIZA??O DA TECNOLOGIA WIMAX NA PREVEN??O DE INC?NDIOS Marília Curado1* , Bruno Sousa1 , Luis as tecnologias sem fios de longo alcance têm vindo a ganhar uma importância crescente à medida que têm mostrado o seu potencial para o suporte de capacidades de transmissão elevadas. A tecnologia Worldwide

Monteiro, Edmundo

341

Nac onal~na akadem nauk Ukra ni KONDENSOVANIH  

E-print Network

kroskop qno- mu p dhod nemo livo oder ati nap vfenomenolog qn gam l~ton a- ni elektron- onno model , k psevdopotenc al v ( model~nih potenc al v na h osnov ) sklada osnovu nap vfenome- nolog qnogo p dhodu do rozv;sCk;s. Model~ (1.1) { (1.2) { nap vfenomenolog qna, ntu tivna. Var anti konstru vann elektron- onnogo model

342

Na/K-ATPase as an oligomeric ensemble.  

PubMed

Differences in the kinetic behavior and properties of monomeric and oligomeric forms of membrane-bound Na/K-ATPase are analyzed. It is concluded that enzyme molecules within oligomeric complexes are affected by extrinsic signals that result in change of enzyme activity, whereas the individual (protomeric) state is insensitive to these signals. Some of the major factors of such regulation are microviscosity of the lipid environment, reactive oxygen species, and intracellular protein kinases. PMID:11566051

Boldyrev, A A

2001-08-01

343

Na\\/K-ATPase as an Oligomeric Ensemble  

Microsoft Academic Search

Differences in the kinetic behavior and properties of monomeric and oligomeric forms of membrane-bound Na\\/K-ATPase are analyzed. It is concluded that enzyme molecules within oligomeric complexes are affected by extrinsic signals that result in change of enzyme activity, whereas the individual (protomeric) state is insensitive to these signals. Some of the major factors of such regulation are microviscosity of the

A. A. Boldyrev

2001-01-01

344

Structure Cristalline de NaAIAs 2O 7  

NASA Astrophysics Data System (ADS)

We present a structural analysis of NaAlAs 2O 7, Mr = 311.81, monoclinic, P2 1/ c, a = 6.9114(7), b = 8.1345(12), c = 9.5446(10) , ? = 107.51(1), V = 511.74. 3, Z = 4, dm = 4.02, dcal= 4.05 g/cm 3, Mo K?, ? = 0.7107 ? = 140.3 cm -1, F (000) = 146, R = 0.039, Rw = 0.038 for all the 1023 independent observed reflections. The structure of NaAlAs 2O 7 is compared to that of the MIMIII P 2O 7 form II diphosphates. The two structures are composed of the same building units, MIII O 6 octahedra and X2 O 7 ( X = As or P) groups. The main difference is that the parts played by the X2O 7 groups and the MIIIO 6 octahedra, as also the stacking of the polyhedra, are exchanged in the two structures. The change is shown to be likely due to the length of the As-O-As bridge and makes it possible to account for the unexpected contraction of the a parameter in NaAlAs 2O 7 in spite of its being the lengthening direction of the X-O- X bridge.

Driss, Ahmed; Jouini, Tahar

1994-10-01

345

Simulation of Na channel inactivation by thiazine dyes  

PubMed Central

Some dyes of the methylene blue family serve as artificial inactivators of the sodium channels when present inside squid axons at a concentration of approximately 0.1 mM. The dyes restore a semblance of inactivation after normal inactivation has been destroyed by pronase. In fibers that inactivate normally, the dyes hasten the decay of sodium current. Many dye-blocked channels conduct transiently on exit of the dye molecule after repolarization to the holding potential. In contrast, normally inactivated channels do not conduct during recovery from inactivation. Kinetic evidence shows that inactivation of a dye- blocked channel is unlikely or impossible, which suggests that dye molecules compete with inactivation "particles" for the same site. In the absence of tetrodotoxin, the dyes do not affect the ON gating current unless the interpulse interval is very short. If sufficient equilibration time is allowed during a pulse, the initial amplitude of the OFF gating current is reduced to near zero. This suggests that a dye molecule is a Na channel completely blocks that channel's gating current, even the fraction that is resistant to normal inactivation. Dyes block INa and Ig with the same time course. This provides the strongest evidence to date that virtually all of recorded "gating current" is associated with Na channels. Tetrodotoxin greatly slows dissociation of dye molecules from Na channels and reduced gating current during both opening and closing of the channels. PMID:6294219

1982-01-01

346

Main Results of Na-K Alloy Boiling Investigation  

SciTech Connect

Boiling experiments on eutectic sodium-potassium alloy in the model of fast reactor subassembly under conditions of low-velocity circulation carried out at the IPPE call for further investigations into numerical modeling of the process. The paper presents analysis of pin bundle liquid metal boiling, stages of the process, its characteristics (wall temperature, coolant temperature, flow rate. pressure void fraction and others), that allowed the pattern map to be drawn. The problem of conversion of the data gained in Na-K mock-up experiments to in-pile sodium reactor operating conditions is analyzed here, as well as thermodynamic similarity of liquid metal coolants and eutectic Na-K alloy. Data on bundle boiling in Na-K are presented in comparison with those in different liquid metals. Analysis of data on liquid metal heat transfer in cases of pool boiling, boiling in tubes, in slots, and in pin bundles, as well as data on critical heat flux in tubes was performed and discussed in the paper. The relationship for calculation of critical heat flux in liquid metal derived by the authors is presented. Results of numerical modeling of liquid metal boiling heat transfer during accident cooling of reactor core applied to experimental conditions of going from forced to natural circulation are presented, too. (authors)

Sorokin, G.A.; Bogoslovskaya, G.P.; Ivanov, E.F.; Sorokin, A.P. [State Scientific Center of Russian Federation Physics and Power Engineering Institute, 1 Bondarenko Sq., Obninsk, 249033, Kaluga Region (Russian Federation)

2002-07-01

347

?-Adducin Stimulates the Thiazide-sensitive NaCl Cotransporter  

PubMed Central

The thiazide-sensitive NaCl cotransporter (NCC) plays a key role in renal salt reabsorption and the determination of systemic BP, but the molecular mechanisms governing the regulation of NCC are not completely understood. Here, through pull-down experiments coupled to mass spectrometry, we found that ?-adducin interacts with the NCC transporter. ?-Adducin colocalized with NCC to the distal convoluted tubule. 22Na+ uptake experiments in the Xenopus laevis oocyte showed that ?-adducin stimulated NCC activity in a dose-dependent manner, an effect that occurred upstream from With No Lysine (WNK) 4 kinase. The binding site of ?-adducin mapped to the N terminus of NCC and encompassed three previously reported phosphorylation sites. Supporting this site of interaction, competition with the N-terminal domain of NCC abolished the stimulatory effect of ?-adducin on the transporter. ?-Adducin failed to increase NCC activity when these phosphorylation sites were constitutively inactive or active. In addition, ?-adducin bound only to the dephosphorylated N terminus of NCC. Taken together, our observations suggest that ?-adducin dynamically regulates NCC, likely by amending the phosphorylation state, and consequently the activity, of the transporter. These data suggest that ?-adducin may influence BP homeostasis by modulating renal NaCl transport. PMID:21164023

Dimke, Henrik; San-Cristobal, Pedro; de Graaf, Mark; Lenders, Jacques W.; Deinum, Jaap; Hoenderop, Joost G.J.

2011-01-01

348

An Examination of Photochemistry Based on INTEX-NA Observations  

NASA Astrophysics Data System (ADS)

Measurements made from the NASA DC8 aircraft over the North American continent and just off its east coast during the summertime 2004 INTEX-NA campaign provide an unprecedented array of photochemical observations for evaluation. This presents the opportunity for detailed analysis of photochemistry over a region that is influenced by significant urban and industrial pollution. The upper tropospheric environment is further influenced by convection and lightning production of NOx. A photochemical box model constrained by INTEX-NA observations of long-lived gases is used to predict radical concentrations. Radical predictions are then compared to measurements to test the fidelity of current photochemical theory, subject to the assumption that concentrations are controlled by local photochemistry. Analysis of the INTEX-NA data shows that discrepancies in the model-to-measurement comparison exist for several trace gases, including HO2 and other species that are dependent on HOx (e.g., peroxides, pernitric acid, aldehydes). While in some cases, discrepancies in the form of model underprediction can be explained by the neglect of convective transport, in many cases, discrepancies are contradictory between the species. Further, for some species such as peroxyacetic acid (PAA) and acetaldehyde, both photochemistry and convective transport fall well short of explaining observed upper tropospheric concentrations.

Olson, J. R.; Crawford, J.; Chen, G.; Brune, W.; Ren, X.; Cohen, R.; Bertram, T.; Fried, A.; Walega, J.; Heikes, B.; O'Sullivan, D.; Huey, G.; Wennberg, P.; Crounse, J.; Kwan, A.

2005-12-01

349

Na+ and Li+ NASICON Superionic Conductors Thick Films  

NASA Astrophysics Data System (ADS)

For microionic applications, superionic conductors have been elaborated in the form of thick films, using silk-screen printable powders. Na3Zr2Si2PO12, Na3.1Zr1.55Si2.3P0.7O11 and Li0.8Zr1.8Ta0.2(PO4)3 compositions are synthesized by a sol-gel process involving hydrolysis-polycondensation reactions of metal-organic alcoholic solutions. A thermal treatment (600C-800C) allows to obtain very fine particles (<1 ?m) with the pure NASICON phase. Inks are prepared with these powders, an organic binder, volatile fluidifying agents and mineralizers. The layers, about 50 ?m in thickness, are achieved by successive deposits and sinterings (950C-1050C) onto alumina substrates. Films conductivity is determined by the complex impedance method. Values measured at 300C (Na+: ?10-2 ?-1cm-1, EA{=}0.25 eV, Li+: ?5 10-4 ?-1cm-1, EA{=}0.5 eV) reach those obtained with well-densified ceramics. An anisotropic behaviour related to microstructure is pointed out.

Perthuis, H.; Velasco, G.; Colomban, Ph.

1984-05-01

350

Bile acids increase the activity of the epithelial Na+ channel.  

PubMed

The epithelial Na(+) channel (ENaC) is a key regulator of Na(+) absorption in various epithelia including the distal nephron and the distal colon. ENaC is a constitutively active channel, but its activity is modulated by a number of mechanisms. These include proteolytic activation, ubiquitination and cell surface expression, phosphorylation, intracellular Na(+) concentration, and shear stress. ENaC is related to the bile acid-sensitive ion channel (BASIC), a channel that is expressed in the epithelial cells of bile ducts. BASIC is activated by millimolar concentrations of extracellular bile acids. Bile acids are synthesized by the liver and secreted into the duodenum to aid lipolysis. A large fraction of the secreted bile acids is absorbed by the ileum and recirculated into the liver, but a small fraction passes the colon and is excreted. Bile acids can influence the ion transport processes in the intestinal tract including the colon. In this study, we show that various bile acids present in rat bile potently and reversibly increase the activity of rat ENaC expressed in Xenopus oocytes, suggesting that bile acids are natural modulators of ENaC activity. PMID:24292109

Wiemuth, Dominik; Lefvre, Cathrine M T; Heidtmann, Hannelore; Grnder, Stefan

2014-09-01

351

Actinic EUV mask inspection beyond 0.25 NA  

SciTech Connect

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benchmarking tests show image contrast above 75% for 100-nm mask features, and significant improvements and across the full range of measured sizes. The zoneplate lens has been replaced by an array of user-selectable zoneplates with higher magnification and NA values up to 0.0875, emulating the spatial resolution of a 0.35-NA 4x EUV stepper. Illumination uniformity is above 90% for mask areas 2-{micro}m-wide and smaller. An angle-scanning mirror reduces the high coherence of the synchrotron beamline light source giving measured {sigma} values of approximately 0.125 at 0.0875 NA.

Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno. B.; Kemp, Charles D.; Huh, S.; Han, H.-S.; Naulleau, P.; Huh, S.

2008-03-24

352

Benchmarking EUV mask inspection beyond 0.25 NA  

SciTech Connect

The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benchmarking tests show image contrast above 75% for 100-nm mask features, and significant improvements and across the full range of measured sizes. The zoneplate lens has been replaced by an array of user-selectable zoneplates with higher magnification and NA values up to 0.0875, emulating the spatial resolution of a 0.35-NA 4 x EUV stepper. Illumination uniformity is above 90% for mask areas 2-{micro}m-wide and smaller. An angle-scanning mirror reduces the high coherence of the synchrotron beamline light source giving measured {sigma} values of approximately 0.125 at 0.0875 NA.

Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno B.; Kemp, Charles D.; Huh, S.; Han, H.-S.; Naulleau, P.; Gunion, R.F.

2008-09-18

353

Characteristics of Mesospheric Na Distribution over Arecibo, Puerto Rico  

NASA Astrophysics Data System (ADS)

We have analyzed 76 nights of mesospheric Na data that are distributed over a year from a low latitude station (18? N). A resonance lidar located at the Arecibo observatory was used to obtain this data set. The goal of this study is to evaluate the seasonal variability in the Na distribution at a low latitude station and compare it with a mid latitude site. A preliminary analysis was undertaken that involved determining the nightly averages and fitting a Gaussian to obtain a mean profile. Further monthly average profiles were obtained, which showed annual variation with concentrations peaking during the June month. This peak was close to ~ 8000 atoms cm-3, maximizing around 93 km. A secondary peak is seen in the November months with densities about 2 times weaker than the primary peak. The average Na abundance over Arecibo is ~ 4.2x109 cm-2 with maximum values ~ 6.7 x 109 atoms cm-3 during the summer seasons. The average FWHM of the layer is about 11 km with a strong evidence of modulation with an average periodicity of 4 months. It is interesting to note that this behavior is in contrast to those observed at mid latitudes (40?N). The possible reasons for this variability will be discussed.

Raizada, S.; Garcia, E.; Garnett Marques Brum, C.; Sarkhel, S.; Cabassa-Miranda, E.; Zhou, Q.; Tepley, C. A.

2013-12-01

354

PRESSURE ADAPTATION OF Na+\\/K+ATPase IN GILLS OF MARINE TELEOSTS  

Microsoft Academic Search

Summary The effects of pressure and temperature on an integral membrane protein, Na + \\/K + -adenosine triphosphatase (Na + \\/K + -ATPase), were studied in fish gill membrane preparations from shallow- and deep-living marine teleosts. The inhibition by pressure of maximal velocity of the enzyme is nonlinear, increasing at higher pressures. Na+\\/K+-ATPases from deep-sea fish were less inhibited by

ALLEN GIBBS; GEORGE N. SOMERO

355

Voltage-dependent inhibition of brain Na + channels by American ginseng  

Microsoft Academic Search

American ginseng (Panax quinquefolius) is a major species of ginseng that has many pharmacological effects. Studies have demonstrated that constituents of ginseng have neuroprotective effects during ischemia. Neuronal damage during ischemic episodes has been associated with abnormal Na+ fluxes. Drugs that block voltage-dependent Na+ channels provide cytoprotection during cerebral ischemia. We thus hypothesized that American ginseng may block Na+ channels.

Dong Liu; Bei Li; Yi Liu; Anoja S. Attele; John W. Kyle; Chun-Su Yuan

2001-01-01

356

First Evidence of Rhombic (NaCl)2 -. Ab Initio Reexamination of the Sodium Chloride  

E-print Network

important ionic compounds and therefore their properties have been the subject of many theoretical-state anionic potential energy surface corresponds to the dipole-bound anion of quasi-linear structure (Na-electron structure (ClNa,,,NaCl)- is considerably higher in energy than the anionic global minimum but its vertical

Simons, Jack

357

Badania Ekologiczne Ryzyka Zachorowa? Na Kleszczowe Zapalenie Mzgu W Polsce-Omwienie Metody  

PubMed Central

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

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

2009-01-01

358

Complete Genome Sequence of Bacillus subtilis subsp. subtilis Strain 3NA  

PubMed Central

Bacillus subtilis 3NA reaches high cell densities during fed-batch fermentation and is an interesting target for further optimization as a production strain. Here, we announce the full genome of B.subtilis 3NA. The presence of specific Bacillus subtilis 168 and W23 genetic features suggests that 3NA is a hybrid of these strains. PMID:25767229

Reu, Daniel R.; Schuldes, Jrg; Daniel, Rolf

2015-01-01

359

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

E-print Network

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

Haseloff, Jim

360

Na?-functionalized carbon quantum dots: a new draw solute in forward osmosis for seawater desalination.  

PubMed

A new type of biocompatible draw solute, Na(+)-functionalized carbon quantum dots (Na_CQDs) with ultra-small size and rich ionic species, in forward osmosis (FO) is developed for seawater desalination. The aqueous dispersion of Na_CQDs demonstrates a high osmotic pressure, which allows high FO water flux and negligible reverse solute permeation. PMID:24870226

Guo, Chun Xian; Zhao, Dieling; Zhao, Qipeng; Wang, Peng; Lu, Xianmao

2014-07-14

361

mTOR Regulates Lysosomal ATP-Sensitive Two-Pore Na+  

E-print Network

membrane. LysoNaATP determines the sensitivity of endolysosome's resting membrane potential to Na's membrane potential, pH stability, and amino acid homeostasis. Mutant mice lacking lysoNaATP have much upon nutrient removal and mTOR translocation off the lysosomal membrane, and controls the lysosome

Clapham, David E.

362

Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region  

E-print Network

Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region above 29 January 2005. [1] Simultaneous sodium (Na) Doppler lidar and meteor radar measurements/s at altitudes below 96 km. This is smaller than the RMS differences observed in a previous Na lidar and meteor

Chu, Xinzhao

363

Excitation of skeletal muscle is a self-limiting process, due to run-down of Na+, K+ gradients, recoverable by stimulation of the Na+, K+ pumps.  

PubMed

The general working hypothesis of this study was that muscle fatigue and force recovery depend on passive and active fluxes of Na(+) and K(+). This is tested by examining the time-course of excitation-induced fluxes of Na(+) and K(+) during 5-300sec of 10-60Hz continuous electrical stimulation in rat extensor digitorum longus (EDL) muscles in vitro and in vivo using (22)Na and flame photometric determination of Na(+) and K(+). 60sec of 60Hz stimulation rapidly increases (22)Na influx, during the initial phase (0-15sec) by 0.53?mol(sec)(-1)(gwetwt.)(-1), sixfold faster than in the later phase (15-60sec). These values agree with flame photometric measurements of Na(+) content. The progressive reduction in the rate of excitation-induced Na(+) uptake is likely to reflect gradual loss of excitability due to accumulation of K(+) in the extracellular space and t-tubules leading to depolarization. This is in keeping with the concomitant progressive loss of contractile force previously demonstrated. During electrical stimulation rat muscles rapidly reach high rates of active Na(+), K(+)-transport (in EDL muscles a sevenfold increase and in soleus muscles a 22-fold increase), allowing efficient and selective compensation for the large excitation-induced passive Na(+), K(+)-fluxes demonstrated over the latest decades. The excitation-induced changes in passive fluxes of Na(+) and K(+) are both clearly larger than previously observed. The excitation-induced reduction in [Na(+)]o contributes considerably to the inhibitory effect of elevated [K(+)]o. In conclusion, excitation-induced passive and active Na(+) and K(+) fluxes are important causes of muscle fatigue and force recovery, respectively. PMID:25862098

Clausen, Torben

2015-04-01

364

Occlusion of 22Na+ and 86Rb+ in membrane-bound and soluble protomeric alpha beta-units of Na,K-ATPase.  

PubMed

In this work, we examined occlusion of 22Na+ and 86Rb+ in membranous and detergent-solubilized Na,K-ATPase from outer renal medulla. Optimum conditions for occlusion of 22Na+ were provided by formation of the phosphorylated complex from the beta,gamma-bidentate complex of chromium (III) with ATP (CrATP). Release of occluded cations occurred at equally slow rates in soluble and membrane-bound Na,K-ATPase. Values of 22Na+ occlusion as high as 11 nmol/mg of protein were measured, corresponding to 1.8-2.7 mol of Na+/mol of phosphorylated Na,K-ATPase as determined by 32P incorporation from [gamma-32P]CrATP. Maximum capacity for phosphorylation from [gamma-32P]CrATP was 6 nmol/mg of protein and equal to capacities for binding of [48V]vanadate and [3H]ouabain. The stoichiometry for occlusion of Rb+ was close to 2 Rb+ ions/phosphorylation site. In an analytical ultracentrifuge, the soluble Na+- or Rb+-occluded complexes showed sedimentation velocities (S20,w = 6.8-7.4) consistent with monomeric alpha beta-units. The data show that soluble monomeric alpha beta-units of Na,K-ATPase can occlude Rb+ or Na+ with the same stoichiometry as the membrane-bound enzyme. The structural basis for occlusion of cations in Na,K-ATPase is suggested to be the formation of a cavity inside a monomeric alpha beta-unit constituting the minimum protein unit required for active Na,K-transport. PMID:3038885

Vilsen, B; Andersen, J P; Petersen, J; Jrgensen, P L

1987-08-01

365

Occlusion of /sup 22/Na+ and /sup 86/Rb+ in membrane-bound and soluble protomeric alpha beta-units of Na,K-ATPase  

SciTech Connect

In this work, we examined occlusion of /sup 22/Na+ and /sup 86/Rb+ in membranous and detergent-solubilized Na,K-ATPase from outer renal medulla. Optimum conditions for occlusion of /sup 22/Na+ were provided by formation of the phosphorylated complex from the beta,gamma-bidentate complex of chromium (III) with ATP (CrATP). Release of occluded cations occurred at equally slow rates in soluble and membrane-bound Na,K-ATPase. Values of /sup 22/Na+ occlusion as high as 11 nmol/mg of protein were measured, corresponding to 1.8-2.7 mol of Na+/mol of phosphorylated Na,K-ATPase as determined by /sup 32/P incorporation from (gamma-/sup 32/P)CrATP. Maximum capacity for phosphorylation from (gamma-/sup 32/P)CrATP was 6 nmol/mg of protein and equal to capacities for binding of (48V)vanadate and (/sup 3/H)ouabain. The stoichiometry for occlusion of Rb+ was close to 2 Rb+ ions/phosphorylation site. In an analytical ultracentrifuge, the soluble Na+- or Rb+-occluded complexes showed sedimentation velocities (S20,w = 6.8-7.4) consistent with monomeric alpha beta-units. The data show that soluble monomeric alpha beta-units of Na,K-ATPase can occlude Rb+ or Na+ with the same stoichiometry as the membrane-bound enzyme. The structural basis for occlusion of cations in Na,K-ATPase is suggested to be the formation of a cavity inside a monomeric alpha beta-unit constituting the minimum protein unit required for active Na,K-transport.

Vilsen, B.; Andersen, J.P.; Petersen, J.; Jorgensen, P.L.

1987-08-05

366

Complex transition metal hydrides incorporating ionic hydrogen: thermal decomposition pathway of Na2Mg2FeH8 and Na2Mg2RuH8.  

PubMed

Complex transition metal hydrides have potential technological application as hydrogen storage materials, smart windows and sensors. Recent exploration of these materials has revealed that the incorporation of anionic hydrogen into these systems expands the potential number of viable complexes, while varying the countercation allows for optimisation of their thermodynamic stability. In this study, the optimised synthesis of Na2Mg2TH8 (T = Fe, Ru) has been achieved and their thermal decomposition properties studied by ex situ Powder X-ray Diffraction, Gas Chromatography and Pressure-Composition Isotherm measurements. The temperature and pathway of decomposition of these isostructural compounds differs considerably, with Na2Mg2FeH8 proceeding via NaMgH3 in a three-step process, while Na2Mg2RuH8 decomposes via Mg2RuH4 in a two-step process. The first desorption maxima of Na2Mg2FeH8 occurs at ca. 400 C, while Na2Mg2RuH8 has its first maxima at 420 C. The enthalpy and entropy of desorption for Na2Mg2TH8 (T = Fe, Ru) has been established by PCI measurements, with the ?Hdes for Na2Mg2FeH8 being 94.5 kJ mol(-1) H2 and 125 kJ mol(-1) H2 for Na2Mg2RuH8. PMID:25732233

Humphries, Terry D; Matsuo, Motoaki; Li, Guanqiao; Orimo, Shin-Ichi

2015-03-11

367

Human Nedd4 interacts with the human epithelial Na+ channel: WW3 but not WW1 binds to Na+-channel subunits.  

PubMed

The epithelial Na(+) channel (ENaC) regulates Na(+) absorption in epithelial tissues including the lung, colon and sweat gland, and in the distal nephrons of the kidney. When Na(+)-channel function is disrupted, salt and water homoeostasis is affected. The cytoplasmic regions of the Na(+)-channel subunits provide binding sites for other proteins to interact with and potentially regulate Na(+)-channel activity. Previously we showed that a proline-rich region of the alpha subunit of the Na(+) channel bound to a protein of 116 kDa from human lung cells. Here we report the identification of this protein as human Nedd4, a ubiquitin-protein ligase that binds to the Na(+)-channel subunits via its WW domains. Further, we show that WW domains 2, 3 and 4 of human Nedd4 bind to the alpha, beta and gamma Na(+)-channel subunits but not to a mutated beta subunit. In addition, when co-expressed in Xenopus oocytes, human Nedd4 down-regulates Na(+)-channel activity. PMID:10642508

Farr, T J; Coddington-Lawson, S J; Snyder, P M; McDonald, F J

2000-02-01

368

A study of the reaction NaO2 + O yields NaO + O2: Implications for the chemistry of sodium in the upper atmosphere  

SciTech Connect

Sodium superoxide (NaO2) is believed to be a major sink for meteor-ablated Na in the upper atmosphere. However, the rate constant for the reaction between NaO2 and O is not known, and its determination is the subject of this study. NaO2 was produced by the reaction between Na vapor, an excess of O2, and the carrier gas N2 in the upstream section of a fast flow tube reactor. Excess atomic O was then added, so that a steady state developed in which the sodium was partitioned between its atomic form and a variety of oxides. The steady state fraction of atomic Na, monitored by laser-induced fluorescence, was then observed as a function of (O) and (O2), from which it was deduced that k(NaO2 + O) = (2.2 +/- 1.0) x 10(exp -11) cu cm/molecule/s at 300 K (3 sigma uncertainty). As a prelude to this experiment, the recombination reaction between O2 and Na was studied by the conventional flow tube technique, yielding k(Na + O2 + N2) = (3.14 +/- 0.20) x 10(exp -30)(300/T)(exp -1.52 +/- 0.27)cm(exp 6)/molecule(exp 2)/s. These experimental results were then incorporated into a one-dimensional model of sodium in the upper atmosphere between 65 and 110 km. It is shown that formation of NaHCO3 rather than NaO2 is the dominant removal process for atomic Na below 90 km. This new model, whole only important assumption is the rate constant for the reaction NaHCO3 + H yields Na + H2CO3, predicts a seasonal variation of the atomic Na layer in excellent agreement with recent lidar observations at 40 deg and 69 deg N and also demonstrates that temperature fluctuations produced by gravity waves should induce significant chemical responses in the Na layer below 88 km.

Helmer, M.; Plane, J.M.C. [Univ. of East Anglia, Norwich (United Kingdom)

1993-12-01

369

Effects of amlodipine on native cardiac Na+ channels and cloned alpha-subunits of cardiac Na+ channels.  

PubMed

The inhibitory effects of amlodipine besilate (CAS 11470-99-6) on the native Na+ current (INa) and cloned human cardiac Na+ channel alpha subunit (hH1) were studied by whole cell patch clamp techniques. Amlodipine produced tonic block of INa in a concentration- and holding potential (HP)-dependent manner with hyperpolarization of H infinity. Amlodipine produced phasic blockade of INa, which was dependent on HP and pulse duration. Amlodipine produced tonic blockade of hH1 in a concentration-dependent manner with 1 : 1 stoichiometry, and phasic blockade of hH1 which was dependent on the pulse duration. Amlodipine blocked INa in a voltage- and frequency-dependent manner via affinity to the resting as well as inactivated conformations of the alpha subunit. PMID:10367100

Inoue, Y; Hisatome, I; Tsuboi, M; Ahmmed, G U; Yatsuhashi, T; Uchida, K; Yamanouchi, Y; Santo, Y; Miake, J; Tanaka, Y; Hamada, T; Watanabe, M; Igawa, O; Yoshida, A; Shigemasa, C; Makita, N; Sato, R

1999-05-01

370

Course # Course Title Instructor Author (s) Title Edition Publisher ISBN MMAE100 Introduction to the Profession Clack, Gosz, Vural NO TEXT REQUIRED NO TEXT REQUIRED N/A N/A N/A  

E-print Network

, and Sustainable Energy Systems Ostrogorsky Weston Energy Conversion: The eBook (http://www.personal.utulsa.edu/~kenneth-weston) 1st Free online N/A MMAE426 (3) Nuclear, Fossil Fuel, and Sustainable Energy Systems Ostrogorsky Lienhardt A Heat Transfer Textbook (http://web.mit.edu/lienhard/www/ahtt.html) 3rd Free online N/A MMAE430

Heller, Barbara

371

K+-dependent Na+ transport driven by respiration in Escherichia coli cells and membrane vesicles.  

PubMed

Respiration-driven Na+ transport from Escherichia coli cells and right-side-out membrane vesicles is strictly dependent on K+. Cells from an E. colic mutant deficient in three major K+ transport systems were incapable of accumulating K+ or expelling Na+ unless valinomycin was added. Membrane vesicles from an E. coli mutant from which the genes encoding the two known electrogenic Na+/nH+ antiporters nhaA and nhaB were deleted transported Na+ as well as did vesicles from wild-type cells. Quantitative analysis of Delta psi and Delta pH showed a high driving force for electrogenic Na+/nH+ antiport whether K+ was present or not, although Na+ transport occurred only in its presence. These results suggest that an Na+/nH+ antiporter is not responsible for the Na+ transport. Respiration-driven efflux of Na+ from vesicles was found to be accompanied by primary uphill efflux of K+. Also, no respiration-dependent efflux of K+ was observed in the absence of Na+. Such coupling between Na+ and K+ fluxes may be explained by the operation of an Na+, K+/H+ antiporter previously described in E. coli membrane vesicles (Verkhovskay, M.L., Verkhovsky, M.I. and Wikstrm, M. (1995) FEBS Lett. 363, 46-48). Active Na+ transport is abolished when delta mu H+ is eliminated by a protonophore, but at low concentrations the protonophore actually accelerated Na+ transport. Such an effect may be expected if the Na+, K+/H+ antiporter normally operates in tight conjunction with respiratory chain complexes, thus exhibiting some phenomenological properties of a primary redox-linked sodium pump. PMID:8616158

Verkhovskaya, M L; Verkhovsky, M I; Wikstrm, M

1996-03-28

372

Spectrophotometric investigation of U(VI) chloride complexation in the NaCl/NaClO{sub 4} system  

SciTech Connect

Post closure radioactive release scenarios from geologic salt formation, such as the WIPP (Waste Isolation Pilot Plant) (USA) include hydrologic transport of radionuclides through a chloride saturated aquifer. Consequently, the understanding of actinide solution chemistry in brines is essential for modeling requiring accurate knowledge of the interaction between AnO{sub 2}{sup 2+} and chloride ions. Complexation constants of two U(VI) chloride species UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0} have been intensively studied for about 40 years using different methods. However, large uncertainties reflect the general difficulty in determining accurate stability constants of weak complexes. In order to model the behavior of U(VI) in brines, the authors studied the formation of its chloride complexes by UV-Vis spectroscopy as a function of the NaCl concentration at 25 C. The experiments were performed at constant ionic strength by varying the concentration ratio of NaCl and NaClO{sub 4}. Deconvolution resulted in single component absorption spectrum for UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0}. The apparent stability constants of UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0} are determined at different ionic strengths. The experimental data are used to parameterize using the SIT approach.

Paviet-Hartmann, P.; Lin, M.R.

1999-07-01

373

Conductivity of aqueous HCl, NaOH and NaCl solutions: Is water just a substrate?  

NASA Astrophysics Data System (ADS)

According to the Arrhenius theory, the ionic conductivity of aqueous electrolytes is realized by the electrolyte ions. Water is considered to be a chemically inactive environmental media. Here, we succeeded in modeling the ionic dc conductivity and dielectric constant of aqueous HCl, NaOH and NaCl solutions without considering Na+ and Cl? ions. Instead, we assumed that i) water has a high concentration of the intrinsic H3O+ and OH? ions (much larger than it is implied by p\\text{H}=7 ), masked in the dc conductivity by the electrophoretic effect, i.e. by a strong ion-ion attraction, and ii) the chemical interaction between the electrolyte molecules and the water ions happens to break down the electrophoretic effect, thus activating the water ions for the dc conductivity. The hypothesis about the active role of water in the conductivity of electrolytes may look controversial, but nevertheless it consistently accounts for a set of basic empirical data and is therefore worth examining.

Artemov, V. G.; Volkov, A. A.; Sysoev, N. N.; Volkov, A. A.

2015-01-01

374

?-NaMnO2: a high-performance cathode for sodium-ion batteries.  

PubMed

There is much interest in Na-ion batteries for grid storage because of the lower projected cost compared with Li-ion. Identifying Earth-abundant, low-cost, and safe materials that can function as intercalation cathodes in Na-ion batteries is an important challenge facing the field. Here we investigate such a material, ?-NaMnO2, with a different structure from that of NaMnO2 polymorphs and other compounds studied extensively in the past. It exhibits a high capacity (of ca. 190 mA h g(-1) at a rate of C/20), along with a good rate capability (142 mA h g(-1) at a rate of 2C) and a good capacity retention (100 mA h g(-1)after 100 Na extraction/insertion cycles at a rate of 2C). Powder XRD, HRTEM, and (23)Na NMR studies revealed that this compound exhibits a complex structure consisting of intergrown regions of ?-NaMnO2 and ?-NaMnO2 domains. The collapse of the long-range structure at low Na content is expected to compromise the reversibility of the Na extraction and insertion processes occurring upon charge and discharge of the cathode material, respectively. Yet stable, reproducible, and reversible Na intercalation is observed. PMID:25397400

Billaud, Juliette; Clment, Raphale J; Armstrong, A Robert; Canales-Vzquez, Jess; Rozier, Patrick; Grey, Clare P; Bruce, Peter G

2014-12-10

375

Thermodynamics of the Na2O-P2O5 system  

NASA Astrophysics Data System (ADS)

The activity of Na2O in the melts of the Na2O-P2O5 system has been determined using a high temperature electrochemical cell with a Na2O-WO3 melt at the reference electrode and fused silica as the solid electrolyte as shown below. _{Na_2 O - WO_3 melt}^{Pt(s),O_2 (g)} left| {_{fused silica}^{ Na^ + } } right|_{Na_2 O - P_2 O_5 melt}^{O_2 (g), Pt(s)} The thermodynamics of the Na2O-P2O5 binary system in the composition range of 50 to 75 mole pet Na2O has been studied. The activities of Na2O and P2O5 in the melt have been carefully analyzed. The free energy of four sodium phosphates has been evaluated with the help of the phase diagram of this system. Based on this study, a solid-state phase transformation for the 3Na2OP2O5 compound has been suggested at a temperature below 1217 K. The entropy of the transformation is near zero. The enthalpy of transformation is estimated to be 101.51 kJ/mole 3Na2OP2O5.

Huang, Chu T.; Lin, Ray Y.

1989-04-01

376

First-Principles Study on Structural and Electronic Properties of ?-S and Na-S Crystals  

NASA Astrophysics Data System (ADS)

Several Na-S solid phases have been considered to be produced in low-temperature Na/S batteries during charge-discharge reactions. We study structural and electronic properties of ?-S and Na2Sx (x = 1, 2, 4, and 5) crystals using first-principles calculations. Calculated structural properties are in good agreement with experiments, and the van der Waals interactions have an essential role on the cohesive properties in ?-S. The results of energetics and electronic structures show that all the calculated Na-S crystal phases are insulating and are stable relative to the elemental Na and S phases. We estimate voltage curves as a function of the Na concentration in the S-cathode of all-solid Na/S batteries, showing mainly three voltage regions at 2.09-2.11, 1.79, and 1.68 V corresponding to the formations of Na2S5 and Na2S4, Na2S2, and Na2S, respectively, for the assumed four-step reactions on the basis of the phase diagram.

Momida, Hiroyoshi; Yamashita, Tomoki; Oguchi, Tamio

2014-12-01

377

Modification of cardiac Na+ channels by batrachotoxin: effects on gating, kinetics, and local anesthetic binding.  

PubMed Central

The purpose of the present study was to examine the characteristics of Na+ channel modification by batrachotoxin (BTX) in cardiac cells, including changes in channel gating and kinetics as well as susceptibility to block by local anesthetic agents. We used the whole cell configuration of the patch clamp technique to measure Na+ current in guinea pig myocytes. Extracellular Na+ concentration and temperature were lowered (5-10 mM, 17 degrees C) in order to maintain good voltage control. Our results demonstrated that 1) BTX modifies cardiac INa, causing a substantial steady-state (noninactivating) component of INa, 2) modification of cardiac Na+ channels by BTX shifts activation to more negative potentials and reduces both maximal gNa and selectivity for Na+; 3) binding of BTX to its receptor in the cardiac Na+ channel reduces the affinity of local anesthetics for their binding site; and 4) BTX-modified channels show use-dependent block by local anesthetics. The reduced blocking potency of local anesthetics for BTX-modified Na+ channels probably results from an allosteric interaction between BTX and local anesthetics for their respective binding sites in the Na+ channel. Our observations that use-dependent block by local anesthetics persists in BTX-modified Na+ channels suggest that this form of extra block can occur in the virtual absence of the inactivated state. Thus, the development of use-dependent block appears to rely primarily on local anesthetic binding to activated Na+ channels under these conditions. PMID:8396458

Wasserstrom, J A; Liberty, K; Kelly, J; Santucci, P; Myers, M

1993-01-01

378

Regulation of cough and action potentials by voltage-gated Na channels.  

PubMed

The classical role ascribed to voltage-gated Na channels is the conduction of action potentials. Some excitable tissues such as cardiac muscle and skeletal muscle predominantly express a single voltage-gated Na channels isoform. Of the nine voltage-gated Na channels, seven are expressed in neurons, of these Nav 1.7, 1.8 and 1.9 are expressed in sensory neurons including vagal sensory neurons that innervate the airways and initiate cough. Nav 1.7 and Nav 1.9 are of particular interest as they represent two extremes in the functional diversity of voltage-gated Na channels. Voltage-gated Na channel isoforms expressed in airway sensory neurons produce multiple distinct Na currents that underlie distinct aspects of sensory neuron function. The interaction between voltage-gated Na currents underlies the characteristic ability of airway sensory nerves to encode encounters with irritant stimuli into action potential discharge and evoke the cough reflex. PMID:23850655

Carr, Michael J

2013-10-01

379

Preparation of zeolite NaA for CO2 capture from nickel laterite residue  

NASA Astrophysics Data System (ADS)

Zeolite NaA was successfully prepared from nickel laterite residue for the first time via a fusion-hydrothermal procedure. The structure and morphology of the as-synthesized zeolite NaA were characterized with a range of experimental techniques, such as X-ray diffraction, scanning electronic microscopy, and infrared spectroscopy. It was revealed that the structures of the produced zeolites were dependent on the molar ratios of the reactants and hydrothermal reaction conditions, so the synthesis conditions were optimized to obtain pure zeolite NaA. Adsorption of nitrogen and carbon dioxide on the prepared zeolite NaA was also measured and analyzed. The results showed that zeolite NaA could be prepared with reasonable purity, it had physicochemical properties comparable with zeolite NaA made from other methods, and it had excellent gas adsorption properties, thus demonstrating that zeolite NaA could be prepared from nickel laterite residue.

Du, Tao; Liu, Li-ying; Xiao, Penny; Che, Shuai; Wang, He-ming

2014-08-01

380

Sodium titanate nanotube/graphite, an electric energy storage device using Na+-based organic electrolytes  

NASA Astrophysics Data System (ADS)

Sodium titanate nanotube (Na-TNT) sample has been prepared by a hydrothermal method using TiO2 and NaOH as starting materials and then calcined at 400 C in air. X-ray diffraction and N2 adsorption-desorption tests have been employed to characterize its crystal and pore structure. The Na-TNT can be used as the negative electrode for electric energy storage devices using Na+-based organic electrolytes. The charge storage mechanism at the Na-TNT negative electrode has been investigated by electrochemical tests (galvanostatic charge-discharge, cyclic voltammetry, etc.), ex-situ XRD and HRTEM measurements. The electric energy storage devices of Na-TNT/graphite have been constructed and the influence of graphite/Na-TNT mass ratio on their performance has been studied.

Zhao, Liping; Qi, Li; Wang, Hongyu

2013-11-01

381

First principles study on the structural, electronic, and elastic properties of Na-As systems  

NASA Astrophysics Data System (ADS)

We have performed the first principles calculation by using the plane-wave pseudopotential approach with the generalized gradient approximation for investigating the structural, electronic, and elastic properties Na-As systems (NaAs in NaP, LiAs and AuCu-type structures, NaAs 2 in MgCu 2-type structure, Na 3As in Na 3As, Cu 3P and Li 3Bi-type structures, and Na 5As 4 in A 5B 4-type structure). The lattice parameters, cohesive energy, formation energy, bulk modulus, and the first derivative of bulk modulus (to fit to Murnaghan's equation of state) of the related structures are calculated. The second-order elastic constants and the other related quantities such as Young's modulus, shear modulus, Poisson's ratio, sound velocities, and Debye temperature are also estimated.

Ozisik, H. B.; Colakoglu, K.; Deligoz, E.; Ozisik, H.

2011-10-01

382

Salt and gene expression: evidence for [Na(+)] i/[K (+)] i-mediated signaling pathways.  

PubMed

Our review focuses on the recent data showing that gene transcription and translation are under the control of signaling pathways triggered by modulation of the intracellular sodium/potassium ratio ([Na+]i/[K+]i). Side-by-side with sensing of osmolality elevation by tonicity enhancer-binding protein (TonEBP, NFAT5), [Na+]i/[K+]i-mediated excitation-transcription coupling may contribute to the transcriptomic changes evoked by high salt consumption. This novel mechanism includes the sensing of heightened Na+ concentration in the plasma, interstitial, and cerebrospinal fluids via augmented Na+ influx in the endothelium, immune system cells, and the subfornical organ, respectively. In these cells, [Na+]i/[K+]i ratio elevation, triggered by augmented Na+ influx, is further potentiated by increased production of endogenous Na+,K+-ATPase inhibitors documented in salt-sensitive hypertension. PMID:25479826

Orlov, Sergei N; Hamet, Pavel

2015-03-01

383

Structure and properties of ?-NaFeO2-type ternary sodium iridates  

NASA Astrophysics Data System (ADS)

The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na3-xMIr2O6 and Na3-xM2IrO6, 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 ?-NaFeO2-type phases with formulas Na1-xM1/3Ir2/3O2 or Na1-xM2/3Ir1/3O2. 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 Na0.62Mn0.61Ir0.39O2, Na0.80Fe2/3Ir1/3O2, Na0.92Ni1/3Ir2/3O2, Na0.86Cu1/3Ir2/3O2, and Na0.89Zn1/3Ir2/3O2 display dominant antiferromagnetic interactions. For Na0.90Co1/3Ir2/3O2 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 Na0.92Ni1/3Ir2/3O2 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. 23Na nuclear magnetic resonance measurements comparing Na2IrO3 to Na0.92Ni1/3Ir2/3O2 and Na0.89Zn1/3Ir2/3O2 provide strong indications that the electron spins are short-range ordered in the latter two materials. Na0.62Mn0.61Ir0.39O2, Na0.80Fe2/3Ir1/3O2, Na0.90Co1/3Ir2/3O2, Na0.92Ni1/3Ir2/3O2, Na0.86Cu1/3Ir2/3O2 and Na0.89Zn1/3Ir2/3O2 are spin glasses. (CSD-numbers: Na0.62Mn0.61Ir0.39O2: 426657, Na0.80Fe2/3Ir1/3O2: 426659, Na0.90Co1/3Ir2/3O2: 426658, Na0.92Ni1/3Ir2/3O2: 426656, Na0.86Cu1/3Ir2/3O2: 426655, and Na2.8ZnIr2O6: 426660.)

Baroudi, Kristen; Yim, Cindi; Wu, Hui; Huang, Qingzhen; Roudebush, John H.; Vavilova, Eugenia; Grafe, Hans-Joachim; Kataev, Vladislav; Buechner, Bernd; Ji, Huiwen; Kuo, Changyang; Hu, Zhiwei; Pi, Tun-Wen; Pao, Chiwen; Lee, Jyhfu; Mikhailova, Daria; Hao Tjeng, Liu; Cava, R. J.

2014-02-01

384

An in vitro investigation of gastrointestinal Na(+) uptake mechanisms in freshwater rainbow trout.  

PubMed

In vitro gut-sac preparations of all four sections (stomach, anterior, mid, and posterior intestine) of the gastrointestinal tract (GIT) of freshwater rainbow trout, together with radiotracer ((22)Na) techniques, were used to study unidirectional Na(+) uptake rates (UR, mucosal?blood space) and net absorptive fluid transport rates (FTR) under isosmotic conditions (mucosal=serosal osmolality). On an area-specific basis, unidirectional Na(+) UR was highest in the mid-intestine, but when total gut area was taken into account, the three intestinal sections contributed equally, with very low rates in the stomach. The theoretical capacity for Na(+) uptake across the whole GIT is sufficient to supply all of the animal's nutritive requirements for Na(+). Transport occurs by low affinity systems with apparent K m values 2-3 orders of magnitude higher than those in the gills, in accord with comparably higher Na(+) concentrations in chyme versus fresh water. Fluid transport appeared to be Na(+)-dependent, such that treatments which altered unidirectional Na(+) UR generally altered FTR in a comparable fashion. Pharmacological trials (amiloride, EIPA, phenamil, bafilomycin, furosemide, hydrochlorothiazide) conducted at a mucosal Na(+) concentration of 50mmolL(-1) indicated that GIT Na(+) uptake occurs by a variety of apical mechanisms (NHE, Na(+) channel/H(+) ATPase, NCC, NKCC) with relative contributions varying among sections. However, at a mucosal Na(+) concentration of 10mmolL(-1), EIPA, phenamil, bafilomycin, and hydrochlorothiazide were no longer effective in inhibiting unidirectional Na(+) UR or FTR, suggesting the contribution of unidentified mechanisms under low Na(+) conditions. A preliminary model is presented. PMID:25183198

Nadella, Sunita R; Patel, Dhanisha; Ng, Allen; Wood, Chris M

2014-12-01

385

Ubiquitination Participates in the Lysosomal Degradation of Na,K-ATPase in Steady-State Conditions  

PubMed Central

The alveolar epithelial cell (AEC) Na,K-ATPase contributes to vectorial Na+ transport and plays an important role in keeping the lungs free of edema. We determined, by cell surface labeling with biotin and immunofluorescence, that approximately 30% of total Na,K-ATPase is at the plasma membrane of AEC in steady-state conditions. The half-life of the plasma membrane Na,K-ATPase was about 4 hours, and the incorporation of new Na,K-ATPase to the plasma membrane was Brefeldin A sensitive. Both protein kinase C (PKC) inhibition with bisindolylmaleimide (10 ?M) and infection with an adenovirus expressing dominant-negative PKC? prevented Na,K-ATPase degradation. In cells expressing the Na,K-ATPase ?1-subunit lacking the PKC phosphorylation sites, the plasma membrane Na,K-ATPase had a moderate increase in half-life. We also found that the Na,K-ATPase was ubiquitinated in steady-state conditions and that proteasomal inhibitors prevented its degradation. Interestingly, mutation of the four lysines described to be necessary for ubiquitination and endocytosis of the Na,K-ATPase in injurious conditions did not have an effect on its half-life in steady-state conditions. Lysosomal inhibitors prevented Na,K-ATPase degradation, and co-localization of Na,K-ATPase and lysosomes was found after labeling and chasing the plasma membrane Na,K-ATPase for 4 hours. Accordingly, we provide evidence suggesting that phosphorylation and ubiquitination are necessary for the steady-state degradation of the plasma membrane Na,K-ATPase in the lysosomes in alveolar epithelial cells. PMID:19286978

Lecuona, Emilia; Sun, Haiying; Vohwinkel, Christine; Ciechanover, Aaron; Sznajder, Jacob I.

2009-01-01

386

Ubiquitination participates in the lysosomal degradation of Na,K-ATPase in steady-state conditions.  

PubMed

The alveolar epithelial cell (AEC) Na,K-ATPase contributes to vectorial Na(+) transport and plays an important role in keeping the lungs free of edema. We determined, by cell surface labeling with biotin and immunofluorescence, that approximately 30% of total Na,K-ATPase is at the plasma membrane of AEC in steady-state conditions. The half-life of the plasma membrane Na,K-ATPase was about 4 hours, and the incorporation of new Na,K-ATPase to the plasma membrane was Brefeldin A sensitive. Both protein kinase C (PKC) inhibition with bisindolylmaleimide (10 microM) and infection with an adenovirus expressing dominant-negative PKCzeta prevented Na,K-ATPase degradation. In cells expressing the Na,K-ATPase alpha1-subunit lacking the PKC phosphorylation sites, the plasma membrane Na,K-ATPase had a moderate increase in half-life. We also found that the Na,K-ATPase was ubiquitinated in steady-state conditions and that proteasomal inhibitors prevented its degradation. Interestingly, mutation of the four lysines described to be necessary for ubiquitination and endocytosis of the Na,K-ATPase in injurious conditions did not have an effect on its half-life in steady-state conditions. Lysosomal inhibitors prevented Na,K-ATPase degradation, and co-localization of Na,K-ATPase and lysosomes was found after labeling and chasing the plasma membrane Na,K-ATPase for 4 hours. Accordingly, we provide evidence suggesting that phosphorylation and ubiquitination are necessary for the steady-state degradation of the plasma membrane Na,K-ATPase in the lysosomes in alveolar epithelial cells. PMID:19286978

Lecuona, Emilia; Sun, Haiying; Vohwinkel, Christine; Ciechanover, Aaron; Sznajder, Jacob I

2009-12-01

387

Hypoxia-mediated Na-K-ATPase degradation requires von Hippel Lindau protein.  

PubMed

Hypoxia inhibits Na-K-ATPase activity and leads to its degradation in mammalian cells. Von Hippel Lindau protein (pVHL) and hypoxia inducible factor (HIF) are key mediators in cellular adaptation to hypoxia; thus, we set out to investigate whether pVHL and HIF participate in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase. We found that in the presence of pVHL hypoxia decreased Na-K-ATPase activity and promoted the degradation of plasma membrane Na-K-ATPase. In pVHL-deficient cells, hypoxia did not decrease the Na-K-ATPase activity and the degradation of plasma membrane Na-K-ATPase was prevented. pVHL-mediated degradation of Na-K-ATPase required the functional pVHL E3 ligase and Ubc5 since pVHL mutants and dominant-negative Ubc5 prevented Na-K-ATPase from degradation. The generation of reactive oxygen species was necessary for pVHL-mediated Na-K-ATPase degradation during hypoxia. Desferrioxamine, which stabilizes HIF1/2alpha, did not affect the half-life of plasma membrane Na-K-ATPase. In addition, stabilizing HIF1/2alpha by infecting mammalian cells with adenoviruses containing the oxygen-dependent degradation domain of HIF1alpha did not affect the plasma membrane Na-K-ATPase degradation. In cells with suppression of pVHL by short hairpin RNA, the Na-K-ATPase was not degraded during hypoxia, whereas cells with knockdown of HIF1/2alpha retained the ability to degrade plasma membrane Na-K-ATPase. These findings suggest that pVHL participates in the hypoxia-mediated degradation of plasma membrane Na-K-ATPase in a HIF-independent manner. PMID:18073334

Zhou, Guofei; Dada, Laura A; Chandel, Navdeep S; Iwai, Kazuhiro; Lecuona, Emilia; Ciechanover, Aaron; Sznajder, Jacob I

2008-05-01

388

Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution.  

PubMed

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 ?9c, a17:1 ?9c 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

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

2013-09-01

389

Quantification of Na+,K+ pumps and their transport rate in skeletal muscle: Functional significance  

PubMed Central

During excitation, muscle cells gain Na+ and lose K+, leading to a rise in extracellular K+ ([K+]o), depolarization, and loss of excitability. Recent studies support the idea that these events are important causes of muscle fatigue and that full use of the Na+,K+-ATPase (also known as the Na+,K+ pump) is often essential for adequate clearance of extracellular K+. As a result of their electrogenic action, Na+,K+ pumps also help reverse depolarization arising during excitation, hyperkalemia, and anoxia, or from cell damage resulting from exercise, rhabdomyolysis, or muscle diseases. The ability to evaluate Na+,K+-pump function and the capacity of the Na+,K+ pumps to fill these needs require quantification of the total content of Na+,K+ pumps in skeletal muscle. Inhibition of Na+,K+-pump activity, or a decrease in their content, reduces muscle contractility. Conversely, stimulation of the Na+,K+-pump transport rate or increasing the content of Na+,K+ pumps enhances muscle excitability and contractility. Measurements of [3H]ouabain binding to skeletal muscle in vivo or in vitro have enabled the reproducible quantification of the total content of Na+,K+ pumps in molar units in various animal species, and in both healthy people and individuals with various diseases. In contrast, measurements of 3-O-methylfluorescein phosphatase activity associated with the Na+,K+-ATPase may show inconsistent results. Measurements of Na+ and K+ fluxes in intact isolated muscles show that, after Na+ loading or intense excitation, all the Na+,K+ pumps are functional, allowing calculation of the maximum Na+,K+-pumping capacity, expressed in molar units/g muscle/min. The activity and content of Na+,K+ pumps are regulated by exercise, inactivity, K+ deficiency, fasting, age, and several hormones and pharmaceuticals. Studies on the ?-subunit isoforms of the Na+,K+-ATPase have detected a relative increase in their number in response to exercise and the glucocorticoid dexamethasone but have not involved their quantification in molar units. Determination of ATPase activity in homogenates and plasma membranes obtained from muscle has shown ouabain-suppressible stimulatory effects of Na+ and K+. PMID:24081980

2013-01-01

390

Excimer lasers for superhigh NA 193-nm lithography  

NASA Astrophysics Data System (ADS)

Excimer lasers are widely used as the light source for microlithography scanners. The volume shipment of scanner systems using 193nm is projected to begin in year 2003. Such tools will directly start with super high numerical aperture (NA) in order to take full advantage of the 193nm wavelength over the advanced 248nm systems. Reliable high repetition rate laser light sources enabling high illumination power and wafer throughput are one of the fundamental prerequisites. In addition these light sources must support a very high NA imaging lens of more than 0.8 which determines the output spectrum of the laser to be less than 0.30 pm FWHM. In this paper we report on our recent progress in the development of high repetition rate ultra-narrow band lasers for high NA 193nm microlithography scanners. The laser, NovaLine A4003, is based on a Single Oscillator Ultral Line-narrowed (SOUL) design which yields a bandwidth of less than 0.30pm FWHM. The SOUL laser enables superior optical performance without adding complexity or cost up to the 4 kHz maximum repetition rate. The A4003's high precision line-narrowing optics used in combination with the high repetition rate of 4 kHz yields an output power of 20 W at an extremely narrow spectral bandwidth of less than 0.30 pm FWHM and highest spectral purity of less than 0.75 pm for the 95% energy content. We present performance and reliability data and discuss the key laser parameters. Improvements in the laser-internal metrology and faster regulation control result in better energy stability and improved overall operation behavior. The design considerations for line narrowing and stable laser operation at high repetition rates are discussed.

Paetzel, Rainer; Albrecht, Hans S.; Lokai, Peter; Zschocke, Wolfgang; Schmidt, Thomas; Bragin, Igor; Schroeder, Thomas; Reusch, Christian; Spratte, Stefan

2003-06-01

391

Phase diagram of the LiNO3-NaNO3-NaCl-Sr(NO3)2 salt system  

NASA Astrophysics Data System (ADS)

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.

Rasulov, A. I.; Gasanaliev, A. M.; Mamedova, A. K.; Gamataeva, B. Yu.

2015-04-01

392

Ghrelin increases growth hormone production and functional expression of NaV1.1 and Na V1.2 channels in pituitary somatotropes.  

PubMed

A variety of ion channels are expressed in the plasma membrane of somatotropes within the anterior pituitary gland. Modification of these channels is linked to intracellular Ca(2+) levels and therefore to hormone secretion. Previous investigations have shown that the gut-derived orexigenic peptide hormone ghrelin and synthetic GH-releasing peptides (GHRPs) stimulate release of growth hormone (GH) and increase the number of functional voltage-gated Ca(2+) and Na(+) channels in the membrane of clonal GC somatotropes. Here, we reveal that chronic treatment with ghrelin and its synthetic analog GHRP-6 also increases GH release from bovine pituitary somatotropes in culture, and that this action is associated with a significant increase in Na(+) macroscopic current. Consistent with this, Na(+) current blockade with tetrodotoxin (TTX) abolished the ghrelin- and GHRP-6-induced increase in GH release. Furthermore, semi-quantitative and real-time RT-PCR analysis revealed an upregulation in the transcript levels of GH, as well as of NaV1.1 and NaV1.2, two isoforms of TTX-sensitive Na(+) channels expressed in somatotropes, after treatment with ghrelin or GHRP-6. These findings improve our knowledge on (i) the cellular mechanisms involved in the control of GH secretion, (ii) the molecular diversity of Na(+) channels in pituitary somatotropes, and (iii) the regulation of GH and Na(+) channel gene expression by ghrelin and GHRPs. PMID:25151402

Magdaleno-Mndez, Adasue; Domnguez, Belisario; Rodrguez-Andrade, Araceli; Barrientos-Morales, Manuel; Cervantes-Acosta, Patricia; Hernndez-Beltrn, Antonio; Gonzlez-Ramrez, Ricardo; Felix, Ricardo

2015-04-01

393

A double-tuned 1H/23Na dual resonator system for tissue sodium concentration measurements in the rat brain via Na-MRI  

NASA Astrophysics Data System (ADS)

A method for quantifying the tissue sodium concentration (TSC) in the rat brain from 23Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered by the extremely low signal to noise ratio (SNR) in 23Na images. To address this, the design, construction and characterization of a double-tuned 1H/23Na dual resonator system for 1H-guided quantitative 23Na-MRI are described. This system comprises an SNR-optimized surface detector coil for 23Na image acquisition, and a volume resonator producing a highly homogeneous B1 field (<5% inhomogeneity) for the Na channel across the rat head. The resonators incorporated channel-independent balanced matching and tuning capabilities with active decoupling circuitry at the 23Na resonance frequency. A quantification accuracy of TSC of <10 mM was achieved in Na-images with 1.2 l voxel resolution acquired in 10 min. The potential of the quantification technique was demonstrated in an in vivo experiment of a rat model of cerebral stroke, where the evolution of the TSC was successfully monitored for 8 h after the stroke was induced.

Wetterling, Friedrich; Tabbert, Martin; Junge, Sven; Gallagher, Lindsay; Mhairi Macrae, I.; Fagan, Andrew J.

2010-12-01

394

A double-tuned (1)H/(23)Na dual resonator system for tissue sodium concentration measurements in the rat brain via Na-MRI.  

PubMed

A method for quantifying the tissue sodium concentration (TSC) in the rat brain from Na-MR images was developed. TSC is known to change in a variety of common human diseases and holds considerable potential to contribute to their study; however, its accurate measurement in small laboratory animals has been hindered by the extremely low signal to noise ratio (SNR) in Na images. To address this, the design, construction and characterization of a double-tuned H/Na dual resonator system for H-guided quantitative Na-MRI are described. This system comprises an SNR-optimized surface detector coil for Na image acquisition, and a volume resonator producing a highly homogeneous B? field (<5% inhomogeneity) for the Na channel across the rat head. The resonators incorporated channel-independent balanced matching and tuning capabilities with active decoupling circuitry at the Na resonance frequency. A quantification accuracy of TSC of <10 mM was achieved in Na-images with 1.2 l voxel resolution acquired in 10 min. The potential of the quantification technique was demonstrated in an in vivo experiment of a rat model of cerebral stroke, where the evolution of the TSC was successfully monitored for 8 h after the stroke was induced. PMID:21113090

Wetterling, Friedrich; Tabbert, Martin; Junge, Sven; Gallagher, Lindsay; Macrae, I Mhairi; Fagan, Andrew J

2010-12-21

395

Composition and Evolution of the Solid-Electrolyte Interphase in Na2Ti3O7 Electrodes for Na-Ion Batteries: XPS and Auger Parameter Analysis.  

PubMed

Na2Ti3O7 is considered a promising negative electrode for Na-ion batteries; however, poor capacity retention has been reported and the stability of the solid-electrolyte interphase (SEI) could be one of the main actors of this underperformance. The composition and evolution of the SEI in Na2Ti3O7 electrodes is hereby studied by means of X-ray photoelectron spectroscopy (XPS). To overcome typical XPS limitations in the photoelectron energy assignments, the analysis of the Auger parameter is here proposed for the first time in battery materials characterization. We have found that the electrode/electrolyte interface formed upon discharge, mostly composed by carbonates and semicarbonates (Na2CO3, NaCO3R), fluorides (NaF), chlorides (NaCl) and poly(ethylene oxide)s, is unstable upon electrochemical cycling. Additionally, solid state nuclear magnetic resonance (NMR) studies prove the reaction of the polyvinylidene difluoride (PVdF) binder with sodium. The powerful approach used in this work, namely Auger parameter study, enables us to correctly determine the composition of the electrode surface layer without any interference from surface charging or absolute binding energy calibration effects. As a result, the suitability for Na-ion batteries of binders and electrolytes widely used for Li-ion batteries is questioned here. PMID:25811538

Muoz-Mrquez, Miguel A; Zarrabeitia, Maider; Castillo-Martnez, Elizabeth; Egua-Barrio, Aitor; Rojo, Tefilo; Casas-Cabanas, Montse

2015-04-15

396

Impact of surface roughness on the electrical parameters of industrial high efficiency NaOH-NaOCl textured multicrystalline silicon solar cell  

SciTech Connect

Sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) solution (1:1 ratio by volume) based texturization process at 80-82 C is an easy, low cost and comparatively new and convenient option for fabrication of any multicrystalline silicon (mC-Si) solar cell. In the present study atomic force microscope is used to observe the intragrain surface in a miniscule area (3 {mu}m x 3 {mu}m) of NaOH-NaOCl textured surface by two and three dimensional analysis, roughness analysis and section analysis. The r.m.s value of the surface parameter of 7.0 nm ascertains the smoothness of the textured surface and further the surface reflectivity is minimized to 4-6% in the 500-1000 nm wavelength range by a proper silicon nitride anti-reflection coating. Comparing with the standard HF-HNO{sub 3}-CH{sub 3}COOH acid textured cell, the NaOH-NaOCl textured cell shows a comparatively lower value of series resistance of 7.17 m{omega}, higher value of shunt resistance of 18.4 {omega} to yield a fill factor of 0.766 leading to more than 15% cell efficiency in the industrial cell processing line. This AFM study yields different surface roughness parameters for the NaOH-NaOCl textured wafers which can be used as a reference standard for optimized texturing. (author)

Basu, P.K. [Department of Physics, Echelon Institute of Technology, Faridabad 121002, Haryana (India); Pujahari, R.M. [Department of Physics, Echelon Institute of Technology, Faridabad 121002, Haryana (India); Department of Physics, Manav Rachna International University, Faridabad 121001, Haryana (India); Kaur, Harpreet [Department of Physics, Manav Rachna International University, Faridabad 121001, Haryana (India); Department of Physics, Advanced Institute of Technology and Management, Palwal 121105, Haryana (India); Singh, Devi [Department of Physics, Manav Rachna International University, Faridabad 121001, Haryana (India); Varandani, D.; Mehta, B.R. [Department of Physics, Indian Institute of Technology, New Delhi 110016 (India)

2010-09-15

397

Solvation structure of I- and Na+ on the surface of NaI aqueous solution studied by photodetachment spectroscopy in combination with mass spectrometry.  

PubMed

We investigated solvation structures of I(-) and Na(+) on an aqueous solution surface by photodetachment spectroscopy and mass spectrometry. An aqueous solution of NaI was introduced into the vacuum as a continuous liquid flow (liquid beam), and the liquid beam was irradiated with a UV laser pulse. The abundance of electrons emitted by the laser excitation was measured as a function of wavelength (photodetachment spectroscopy). For a concentrated aqueous solution of NaI, we observe an absorption peak at longer wavelengths than the charge-transfer-to-solvent band of I(-) in solution. This feature is assigned to the photoabsorption of I(-) at the surface. This finding indicates that when the concentration of NaI is high (>1.0 M), I(-) exists on the solution surface. The identity of the ion clusters ejected from the liquid beam following selective laser excitation of I(-) on the surface or I(-) inside the solution was revealed by mass spectrometry. The mass spectra show that Na rich clusters are formed when I(-) inside the solution is excited, whereas Na rich clusters are hardly formed by the excitation of surface I(-). These findings lead us to conclude that Na(+) does not exist on the surface of the NaI aqueous solution. PMID:21366280

Shoji, Makoto; Kaniwa, Keisuke; Hiranuma, Yojiro; Maselli, Olivia; Mafun, Fumitaka

2011-03-24

398

Nanoscale Manufacturing Curriculum for Advanced Technological Education (NaMCATE)  

NSDL National Science Digital Library

The project (NaMCATE) is developing benchmarks for nanomanufacturing and eleven nanomanufacturing curriculum modules for community college levels.The project is a collaborative effort of high school, community college and university faculty in New York State and at Arizona State University. The Student Zone of this site has fantastic resources for nanotechnology high school or community college classrooms including an Overview of Nanotechnology, and Bottom-Up and Top-Down Nanomanufacturing. Each section has three or four modules, and each module has reading material, learning activities, assessments, and supplemental presentations. There are also a number of videos and simulations of nanomanufacturing processes.

399

Analysis of Cl and Na in Hyperimmune Sera by NAA  

NASA Astrophysics Data System (ADS)

The Cl and Na concentration values in four types of hyperimmune sera (anti-Bothrops, anti-Diphtheria, anti-Rabies and anti-Tetanus) used for immunological therapy were determined using Neutron Activation Analysis (NAA). These data were compatible with the specifications established by the Word Health Organization (WHO-OMS) and with the Brazilian Official Pharmacopea (Pharmaceutical Code Official of the Country). These data are an important support for quality control of hyperimmune sera production at Butantan Institute (So Paulo city, Brazil), responsible for supplying the Brazilian market.

Baptista, T. S.; Zamboni, C. B.; Marcelino, J. R.

2011-08-01

400

Beta-Gamma-Angular Correlation in Na-20  

E-print Network

set on the TOF peaks to en- sure that they would not induce energy-dependent asymmetries. Typical coincidence P and y spec- tra are shown in Fig. 2. There is a significant background seen in the y spectra that is due to coincidences between... REACTIONS Radioactivity Na; measured p-p angular correlation. Determined induced weak currents. I. INTRODUCTION Recently, ' we gave a detailed accounting of our measurement of the p-y angular correlation for the decay of "F-"Ne* (2', E?=1.63 MeV}+ e...

Tribble, Robert E.; May, D. P.; Tanner, D. M.

1981-01-01

401

New reference electrode for Na/MCI2 batteries  

NASA Astrophysics Data System (ADS)

The use of aluminum as a reference electrode in the neutral and basic chloroaluminate molten salts poses certain problems related to the uncertainty and irreproducibility in the measured electrode potential as well as lack of stability in long-term studies. A new reference electrode based on an insoluble transition metal chloride, e.g., NiCl2 is proposed to address these problems. Ni/NiCl2 forms an electrode of the second kind with high exchange current density and long durability and would be an ideal choice for the electrochemical studies in neutral and basic chloroaluminate melts, including Na/NiCl2 cells.

Ratnakumar, B. V.; Attia, A. I.; Surampudi, S.; Halpert, G.

1993-12-01

402

Pregled slovenske esejistike na temo slovenske literarne ustvarjalnosti  

E-print Network

. Ferdo Kozak, Stanko Leben, Josip Vidmar. 13236. Filip KALAN, 1957: Trije predhodniki sodobne dramatike v Jugoslaviji. Naa sodobnost 5/10. Ur. Drago ega. 865872. Vinko MDERNDORFER, 2001: Gledali?e v ogledalu: gledalika razmiljanja... in travestije: 19861998. Maribor: Obzorja. Michel de MONTAIGNE, 1960: Eseji. Izbor. Ljubljana: Mladinska knjiga. Drago EGA, 1951: O preprostih zgodbah. Novi svet 6/6. Ur. Ju Kozak, Ferdo Kozak. Ljubljana: Dravna zaloba Slovenije. 518535. Tomo VIRK...

Bergles, Katja

2011-02-01

403

Ferroelectricity in antiferroelectric NaNbO3 crystal.  

PubMed

Sodium niobate (NaNbO3, or NNO) is known to be antiferroelectric at temperatures between 45 and 753 K. Here we show experimentally the presence of the ferroelectric phase at temperatures between 100 and 830 K in the NNO crystals obtained by top-seeded solution growth. The ferroelectric phase and new phase transitions are evidenced using a combination of thermo-optical studies by variable angle spectroscopic ellipsometry, Raman spectroscopy analysis, and photoelectron emission microscopy. The possibility for strain-induced ferroelectricity in NNO is suggested. PMID:24594846

Tyunina, M; Dejneka, A; Rytz, D; Gregora, I; Borodavka, F; Vondracek, M; Honolka, J

2014-03-26

404

Soft acoustic modes in NaN3  

NASA Astrophysics Data System (ADS)

Brillouin scattering measurements in the high-temperature phase of NaN3 are reported. A five-pass Fabry-Perot interferometer was used to analyze the scattered radiation. Soft modes whose velocity extrapolated to zero at TC-2C were observed. Here TC is trigonal to monoclinic transition temperature. No appreciable line broadening in the Brillouin spectra nor changes in intensity of the central scattering peak were observed. The measurements provide the first data on these soft modes. They indicate that the transition is almost a prototype displacive rather than an order-disorder transition.

Kushida, Toshimoto; Terhune, R. W.

1984-09-01

405

Project ELaNa and NASA's CubeSat Initiative  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the NASA program to use expendable lift vehicles (ELVs) to launch nanosatellites for the purpose of enhancing educational research. The Education Launch of Nanosatellite (ELaNa) project, run out of the Launch Services Program is requesting proposals for CubeSat type payload to provide information that will aid or verify NASA Projects designs while providing opportunities for higher educational research. Some of the challenges involved with the program are discussed, and there is brief discussion about requirements for participation in the program, and the number of flight opportunities available for the launch of the Poly Picosatellite Orbital Deployer (PPOD).

Skrobot, Garrett Lee

2010-01-01

406

The toxicity of NaF on BmN cells and a comparative proteomics approach to identify protein expression changes in cells under NaF-stress: Impact of NaF on BmN cells.  

PubMed

Fluorides negatively affect the development of organisms and are a threat to human health and environmental safety. In this study, Bombyx mori N cell line (BmN) were used to explore effects of NaF on insect cells. We found that 8h (hrs) culture with high concentration of NaF (?1mM) induced significantly morphological changes. Dose-response curves of 72h continuously cultured BmN treated with NaF showed that the half inhibitory concentration (IC50) value was 56.60?M. Treatment of BmN with 100 and 300?M of NaF induced apoptosis and necrosis. 2-D electrophoresis of whole cell extracted from BmN showed that treatment with 300?M NaF up-regulated 32 proteins and down-regulated 11 proteins when compared with controls. We identified 5 different proteins by MALDI-TOF MS, and 4 of them were identified for the first time, including 2 up-regulated proteins (mitochondrial aldehyde dehydrogenase ALDH2 and prohibitin protein WPH) and 2 down-regulated proteins (calreticulin precursor CRT and DNA supercoiling factor SCF). These observations were further confirmed by fluorescence quantitative PCR. Together, our data suggest that these target proteins could be regarded as targets influenced by NaF and also provide clues for studies on the response metabolism pathway under NaF stress. PMID:25661258

Chen, Liang; Chen, Huiqing; Yao, Chun; Chang, Cheng; Xia, Hengchuan; Zhang, Chunxia; Zhou, Yang; Yao, Qin; Chen, Keping

2015-04-01

407

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

PubMed Central

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 2.04.55?V. PMID:24595232

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

2014-01-01

408

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

409

The Voltage-Gated Na+ Channel NaVBP Co-localizes with Methyl-Accepting Chemotaxis Protein at Cell Poles of Alkaliphilic Bacillus pseudofirmus OF4  

PubMed Central

Summary NaVBP is the member of the bacterial voltage-gated Na+ channel superfamily found in alkaliphilic Bacillus pseudofirmus OF4. The alkaliphile requires NaVBP for normal chemotaxis responses and for optimal pH homeostasis during a shift to alkaline conditions at sub-optimally low [Na+]. We hypothesized that interaction of NaVBP with one or more other proteins in vivo, specifically methyl-accepting chemotaxis proteins (MCPs), is involved in activation of the channel under the pH conditions that exist in the extremophile and could underpin its role in chemotaxis; MCPs transduce chemotactic signals and generally localize to cell poles of rod-shaped cells. Here, immunofluorescence microscopy and fluorescent protein fusion studies showed that an alkaliphile protein (designated McpX) that cross-reacts with antibodies raised against Bacillus subtilis McpB co-localizes with NaVBP at the cell poles of B. pseudofirmus OF4. In a mutant in which NaVBP-encoding ncbA is deleted, the content of McpX was close to the wild-type level but McpX was significantly delocalized. A mutant of B. pseudofirmus OF4 was constructed in which cheAW expression was disrupted to assess whether this mutation impaired polar localization of McpX, as expected from studies in Escherichia coli and Salmonella, and, if so, whether NaVBP would be similarly affected. Polar localization of both McpX and NaVBP was decreased in the cheAW mutant. The results suggest interactions between McpX and NaVBP that affect their co-localization. The inverse chemotaxis phenotype of ncbA mutants may result in part from MCP delocalization. PMID:18048917

Fujinami, Shun; Sato, Takako; Trimmer, James S.; Spiller, Benjamin W.; Clapham, David E.; Krulwich, Terry A.; Kawagishi, Ikuro; Ito, Masahiro

2008-01-01

410

Actions of veratridine on tetrodotoxin-sensitive voltage-gated Na+ currents, NaV1.6, in murine vas deferens myocytes  

PubMed Central

Background and purpose: The effects of veratridine, an alkaloid found in Liliaceae plants, on tetrodotoxin (TTX)-sensitive voltage-gated Na+ channels were investigated in mouse vas deferens. Experimental approach: Effects of veratridine on TTX-sensitive Na+ currents (INa) in vas deferens myocytes dispersed from BALB/c mice, homozygous mice with a null allele of NaV1.6 (NaV1.6?/?) and wild-type mice (NaV1.6+/+) were studied using patch-clamp techniques. Tension measurements were also performed to compare the effects of veratridine on phasic contractions in intact tissues. Key results: In whole-cell configuration, veratridine had a concentration-dependent dual action on the peak amplitude of INa: INa was enhanced by veratridine (110 M), while higher concentrations (?30 M) inhibited INa. Additionally, two membrane current components were evoked by veratridine, namely a sustained inward current during the duration of the depolarizing rectangular pulse and a tail current at the repolarization. Although veratridine caused little shift of the voltage dependence of the steady-state inactivation curve and the activation curve for INa, veratridine enhanced a non-inactivating component of INa. Veratridine caused no detectable contractions in vas deferens from NaV1.6?/? mice, although in tissues from NaV1.6+/+ mice, veratridine (?3 M) induced TTX-sensitive contractions. Similarly, no detectable inward currents were evoked by veratridine in NaV1.6?/? vas deferens myocytes, while veratridine elicited both the sustained and tail currents in cells taken from NaV1.6+/+ mice. Conclusions and implications: These results suggest that veratridine possesses a dual action on INa and that the veratridine-induced activation of contraction is induced by the activation of NaV1.6 channels. PMID:19552689

Zhu, Hai-Lei; Wassall, Richard D; Takai, Maki; Morinaga, Hidetaka; Nomura, Masatoshi; Cunnane, Thomas C; Teramoto, Noriyoshi

2009-01-01

411

Cell Degradation of a Na-NiCl2 (ZEBRA) Battery  

SciTech Connect

In this work, the parameters influencing the degradation of a Na-NiCl2 (ZEBRA) battery were investigated. Planar Na-NiCl2 cells using ?-alumina solid electrolyte (BASE) were tested with different C-rates, Ni/NaCl ratios, and capacity windows, in order to identify the key parameters for the degradation of Na-NiCl2 battery. The morphology of NaCl and Ni particles were extensively investigated after 60 cycles under various test conditions using a scanning electron microscope. A strong correlation between the particle size (NaCl and Ni) and battery degradation was observed in this work. Even though the growth of both Ni and NaCl can influence the cell degradation, our results indicate that the growth of NaCl is a dominant factor in cell degradation. The use of excess Ni seems to play a role in tolerating the negative effects of particle growth on degradation since the available active surface area of Ni particles can be still sufficient even after particle growth. For NaCl, a large cycling window was the most significant factor, of which effects were amplified with decrease in Ni/NaCl ratio.

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.

2013-11-01

412

Regulation of Electroneutral NaCl Absorption by the Small Intestine  

PubMed Central

Na+ and Cl? movement across the intestinal epithelium occurs by several interconnected mechanisms: (1) nutrient coupled Na+ absorption; (2) electroneutral NaCl absorption; (3) electrogenic Cl? secretion by CFTR; and (4) electrogenic Na+ absorption by ENaC. All of these transport modes require a favorable electrochemical gradient maintained by the basolateral Na+-K+-ATPase, a Cl? channel and K+ channels. Electroneutral NaCl absorption is observed from the small intestine to distal colon. This transport is mediated by apical Na+/H+ (NHE2/3) and Cl?/HCO3 ? (Slc26a3/a6, others) exchangers that provide the major route of NaCl absorption. Electroneutral NaCl absorption and Cl? secretion by CFTR are oppositely regulated by the autonomic nerve system, immune system, and endocrine system via PKA?, PKC?, cGKII, and/or SGK1. This integrated regulation requires the formation of macromolecular complexes, which mediated by NHERF family of scaffold proteins, and involve internalization of NHE3. Using knockout mice and human mutations, a more detailed understanding of the integrated as well as subtle regulation of electroneutral NaCl absorption by the mammalian intestine has emerged. PMID:21054167

Kato, Akira; Romero, Michael F.

2014-01-01

413

Na+/H+ Antiport in Isolated Tonoplast Vesicles from Storage Tissue of Beta vulgaris1  

PubMed Central

The pH-dependent fluorescence quenching of acridine orange was used to study the Na+- and K+-dependent H+ fluxes in tonoplast vesicles isolated from storage tissue of red beet and sugar beet (Beta vulgaris L.). The Na+-dependent H+ flux across the tonoplast membrane could be resolved into two components: (a) a membrane potential-mediated flux through conductive pathways; and (b) an electroneutral flux which showed Michaelis-Menten kinetics relationship to Na+ concentration and was competitively inhibited by amiloride (Ki = 0.1 millimolar). The potential-dependent component of H+ flux showed an approximately linear dependence on Na+ concentration. In contrast, the K+-dependent H+ flux apparently consisted of a single component which showed an approximately linear dependence on K+ concentration, and was insensitive to amiloride. Based on the Na+- and K+-dependent H+ fluxes, the passive permeability of the vesicle preparation to Na+ was about half of that to K+. The apparent Km for Na+ of the electroneutral Na+/H+ exchange varied by more than 3-fold (7.5-26.5 millimolar) when the internal and external pH values were changed in parallel. The results suggest a simple kinetic model for the operation of the Na+/H+ antiport which can account for the estimated in vivo accumulation ratio for Na+ into the vacuole. PMID:16664191

Blumwald, Eduardo; Poole, Ronald J.

1985-01-01

414

Formation of titanate nanostructures under different NaOH concentration and their application in wastewater treatment  

SciTech Connect

The effects of the concentration of NaOH on the formation and transformation of various titanate nanostructures were studied. With increasing NaOH concentration, three different formation mechanisms were proposed. Nanotubes can only be obtained under moderate NaOH conditions, and should transform into nanowires with prolonged hydrothermal treatment, and their formation rate is accelerated by increasing NaOH concentration. Low concentration of NaOH results in the direct formation of nanowires, while extra high concentration of NaOH leads to the formation of amorphous nanoparticles. Adsorption and photocatalysis studies show that titanate nanowires and nanotubes might be potential adsorbents for the removal of both heavy metal ions and dyes and photocatalysts for the removal of dyes from wastewater. -- Graphical abstract: The morphologies of the titanates depend deeply on the concentration of NaOH. With increasing NaOH concentration, three different formation mechanisms were proposed. The application of these titanate nanostructures in the wastewater treatment was studied. Display Omitted Research highlights: {yields} Effect of NaOH concentration on the structures of various titanates was reported. {yields} Three different formation mechanisms were presented with increasing NaOH concentration. {yields} Various titanates were used as adsorbents/photocatalysts in wastewater treatment.

Huang Jiquan [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Graduate school of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100049 (China); Cao Yongge, E-mail: caoyongge@fjirsm.ac.c [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China); Deng Zhonghua; Tong Hao [Key Lab of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)

2011-03-15

415

Morphological, Physiological, and Structural Responses of Two Species of Artemisia to NaCl Stress  

PubMed Central

Effects of salt stress on Artemisia scoparia and A. vulgaris Variegate were examined. A. scoparia leaves became withered under NaCl treatment, whereas A. vulgaris Variegate leaves were not remarkably affected. Chlorophyll content decreased in both species, with a higher reduction in A. scoparia. Contents of proline, MDA, soluble carbohydrate, and Na+ increased in both species under salt stress, but A. vulgaris Variegate had higher level of proline and soluble carbohydrate and lower level of MDA and Na+. The ratios of K+/Na+, Ca2+/Na+, and Mg2+/Na+ in A. vulgaris Variegate under NaCl stress were higher. Moreover, A. vulgaris Variegate had higher transport selectivity of K+/Na+ from root to stem, stem to middle mature leaves, and upper newly developed leaves than A. scoparia under NaCl stress. A. vulgaris Variegate chloroplast maintained its morphological integrity under NaCl stress, whereas A. scoparia chloroplast lost integrity. The results indicated that A. scoparia is more sensitive to salt stress than A. vulgaris Variegate. Salt tolerance is mainly related to the ability of regulating osmotic pressure through the accumulation of soluble carbohydrates and proline, and the gradient distribution of K+ between roots and leaves was also contributed to osmotic pressure adjustment and improvement of plant salt tolerance. PMID:24235883

Guan, Zhi-Yong; Su, Yi-Ji; Teng, Nian-Jun; Chen, Su-Mei; Sun, Hai-Nan; Li, Chu-Ling; Chen, Fa-Di

2013-01-01

416

High sodium ion conductivity of glass-ceramic electrolytes with cubic Na3PS4  

NASA Astrophysics Data System (ADS)

Sulfide solid electrolytes with cubic Na3PS4 phase has relatively high sodium ion conductivity of over 10-4Scm-1 at room temperature, and all-solid-state sodium batteries Na-Sn/TiS2 with the electrolyte operated as a secondary battery at room temperature. To improve battery performance, conductivity enhancement of sulfide electrolytes is important. In this study, we have succeeded in enhancing conductivity by optimizing preparation conditions of Na3PS4 glass-ceramic electrolytes. By use of crystalline Na2S with high purity of 99.1%, cubic Na3PS4 crystals were directly precipitated by ball milling process at the composition of 75Na2S25P2S5 (mol%). The glass-ceramic electrolyte prepared by milling for 1.5h and consecutive heat treatment at 270C for 1h showed the highest conductivity of 4.6נ10-4Scm-1, which is twice as high as the conductivity of the cubic Na3PS4 glass-ceramic prepared in a previous report. All-solid-state Na-Sn/NaCrO2 cells with the newly prepared electrolyte exhibited charge-discharge cycles at room temperature and kept about 60mAh per gram of NaCrO2 for 15 cycles.

Hayashi, Akitoshi; Noi, Kousuke; Tanibata, Naoto; Nagao, Motohiro; Tatsumisago, Masahiro

2014-07-01

417

ANG-2 for quantitative Na(+) determination in living cells by time-resolved fluorescence microscopy.  

PubMed

Sodium ions (Na(+)) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na(+) concentrations ([Na(+)]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na(+)-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na(+)-sensitivity appropriate for recordings in living cells. The Na(+)-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na(+)]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na(+)]i rise in cockroach salivary gland cells, which was dependent on a Na(+)-K(+)-2Cl(-) cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems. PMID:25311309

Roder, Phillip; Hille, Carsten

2014-12-01

418

The role of cAMP-mediated intracellular signaling in regulating Na+ uptake in zebrafish larvae  

PubMed Central

In the current study, the role of cAMP in stimulating Na+ uptake in larval zebrafish was investigated. Treating larvae at 4 days postfertilization (dpf) with 10 ?M forskolin or 1 ?M 8-bromo cAMP significantly increased Na+ uptake by three-fold and twofold, respectively. The cAMP-dependent stimulation of Na+ uptake was probably unrelated to protein trafficking via microtubules because pretreatment with 200 ?M colchicine or 30 ?M nocodazole did not attenuate the magnitude of the response. Na+ uptake was stimulated markedly following acute (2 h) exposure to acidic water. The acid-induced increase in Na+ uptake was accompanied by a twofold elevation in whole body cAMP levels and attenuated by inhibiting PKA with 10 ?M H-89. Knockdown of Na+-H+ exchanger 3b (NHE3b) attenuated, but did not abolish, the stimulation of Na+ uptake during forskolin treatment. In glial cell missing 2 morphants, in which the role of NHE3b in Na+ uptake is diminished and the Na+-Cl? cotransporter (NCC) becomes the predominant route of Na+ entry, forskolin treatment continued to increase Na+ uptake. These data suggest that at least NHE3b and NCC are targeted by cAMP in zebrafish larvae. Staining of larvae with fluorescent forskolin and propranolol revealed the presence of transmembrane adenylyl cyclase within multiple subtypes of ionocytes expressing ?-adrenergic receptors. Taken together, results of the present study demonstrate that cAMP-mediated intracellular signaling may regulate multiple Na+ transporters and plays an important role in regulating Na+ uptake in zebrafish larvae during acute exposure to an acidic environment. PMID:24259461

Kumai, Yusuke; Kwong, Raymond W. M.

2013-01-01

419

Linking salinity stress tolerance with tissue-specific Na+ sequestration in wheat roots  

PubMed Central

Salinity stress tolerance is a physiologically complex trait that is conferred by the large array of interacting mechanisms. Among these, vacuolar Na+ sequestration has always been considered as one of the key components differentiating between sensitive and tolerant species and genotypes. However, vacuolar Na+ sequestration has been rarely considered in the context of the tissue-specific expression and regulation of appropriate transporters contributing to Na+ removal from the cytosol. In this work, six bread wheat varieties contrasting in their salinity tolerance (three tolerant and three sensitive) were used to understand the essentiality of vacuolar Na+ sequestration between functionally different root tissues, and link it with the overall salinity stress tolerance in this species. Roots of 4-day old wheat seedlings were treated with 100 mM NaCl for 3 days, and then Na+ distribution between cytosol and vacuole was quantified by CoroNa Green fluorescent dye imaging. Our major observations were as follows: (1) salinity stress tolerance correlated positively with vacuolar Na+ sequestration ability in the mature root zone but not in the root apex; (2) contrary to expectations, cytosolic Na+ levels in root meristem were significantly higher in salt tolerant than sensitive group, while vacuolar Na+ levels showed an opposite trend. These results are interpreted as meristem cells playing a role of the salt sensor; (3) no significant difference in the vacuolar Na+ sequestration ability was found between sensitive and tolerant groups in either transition or elongation zones; (4) the overall Na+ accumulation was highest in the elongation zone, suggesting its role in osmotic adjustment and turgor maintenance required to drive root expansion growth. Overall, the reported results suggest high tissue-specificity of Na+ uptake, signaling, and sequestration in wheat roots. The implications of these findings for plant breeding for salinity stress tolerance are discussed. PMID:25750644

Wu, Honghong; Shabala, Lana; Liu, Xiaohui; Azzarello, Elisa; Zhou, Meixue; Pandolfi, Camilla; Chen, Zhong-Hua; Bose, Jayakumar; Mancuso, Stefano; Shabala, Sergey

2015-01-01

420

Transient state kinetic evidence for an oligomer in the mechanism of Na sup + -H sup + exchange  

SciTech Connect

Pre-steady-state kinetic measurements of {sup 22}Na{sup +} uptake by the amiloride-sensitive Na{sup +}-H{sup +} exchanger in renal brush border membrane vesicles (BBMV) were performed at 0{degree}C to characterize the intermediate reactions of the exchange cycle. At 1 mM Na{sup +}, the initial time course of Na{sup +} uptake was resolved into three separate components: (i) a lag phase, (ii) an exponential or burst phase, and (iii) a constant velocity or steady-state phase. Pulse-chase experiments using partially loaded BBMV showed no evidence for {sup 22}Na{sup +} backflux, suggesting that the decline in the rate of Na{sup +} uptake rate following the burst represents completion of the first turnover of the exchanger. Gramicidin completely abolished Na{sup +} uptake, indicating that the burst phase results from the translocation of Na{sup +} rather than from residual Na{sup +} binding to external sites. Raising the (Na{sup +}) from 1 to 10 mM at constant pH produced a sigmoidal increase in the amplitude of the burst phase without affecting the lag duration or the apparent burst rate. These results suggest that a minimum of two Na{sup +} transport sites must be occupied to activate Na{sup +} uptake in the pre-steady state. The transition to Michaelis-Menten kinetics in the steady state can be explained by a flip-flop or alternating site mechanism in which the functional transport unit is an oligomer and only one protomer per cycle is allowed to form a translocation complex with Na{sup +} after the first turnover.

Otsu, K.; Kinsella, J.; Sacktor, B.; Froehlich, J.P. (National Institutes of Health, Baltimore, MD (USA))

1989-07-01

421

Correction of the Caulobacter crescentus NA1000 genome annotation.  

PubMed

Bacterial genome annotations are accumulating rapidly in the GenBank database and the use of automated annotation technologies to create these annotations has become the norm. However, these automated methods commonly result in a small, but significant percentage of genome annotation errors. To improve accuracy and reliability, we analyzed the Caulobacter crescentus NA1000 genome utilizing computer programs Artemis and MICheck to manually examine the third codon position GC content, alignment to a third codon position GC frame plot peak, and matches in the GenBank database. We identified 11 new genes, modified the start site of 113 genes, and changed the reading frame of 38 genes that had been incorrectly annotated. Furthermore, our manual method of identifying protein-coding genes allowed us to remove 112 non-coding regions that had been designated as coding regions. The improved NA1000 genome annotation resulted in a reduction in the use of rare codons since noncoding regions with atypical codon usage were removed from the annotation and 49 new coding regions were added to the annotation. Thus, a more accurate codon usage table was generated as well. These results demonstrate that a comparison of the location of peaks third codon position GC content to the location of protein coding regions could be used to verify the annotation of any genome that has a GC content that is greater than 60%. PMID:24621776

Ely, Bert; Scott, LaTia Etheredge

2014-01-01

422

Cosmogenic radionuclide production in NaI(Tl) crystals  

E-print Network

The production of long-lived radioactive isotopes in materials due to the exposure to cosmic rays on Earth surface can be an hazard for experiments demanding ultra-low background conditions, typically performed deep underground. Production rates of cosmogenic isotopes in all the materials present in the experimental set-up, as well as the corresponding cosmic rays exposure history, must be both well known in order to assess the relevance of this effect in the achievable sensitivity of a given experiment. Although NaI(Tl) scintillators are being used in experiments aiming at the direct detection of dark matter since the first nineties of the last century, very few data about cosmogenic isotopes production rates have been published up to date. In this work we present data from two 12.5 kg NaI(Tl) detectors, developed in the frame of the ANAIS project, which were installed inside a convenient shielding at the Canfranc Underground Laboratory just after finishing surface exposure to cosmic rays. The very fast star...

Amar, J; Cuesta, C; Garca, E; Ginestra, C; Martnez, M; Olivn, M A; Ortigoza, Y; de Solrzano, A Ortiz; Pobes, C; Puimedn, J; Sarsa, M L; Villar, J A; Villar, P

2014-01-01

423

Molecular simulation study of hydrated Na-rectorite.  

PubMed

The swelling behavior of clay minerals is an important issue in industrial processes and environmental applications. Mixed-layer clay minerals containing a smectite fraction, such as rectorite, are neglected even though they could swell and exist in nature widely. The hydration of rectorite has not been well comprehended even though they are meaningful to mineralogy and industry. This study combines molecular dynamics (MD) and Monte Carlo (MC) simulations to disclose the swelling behavior of rectorite and compare with montmorillonite. From grand canonical Monte Carlo (GCMC) and MD simulations, we obtain swelling curves and swelling free-energy curves of rectorite with a relative humidity of 100%. With the comparisons of swelling free-energy minima, we find that the bilayer hydrate of Na-rectorite is more thermodynamically stable than the monolayer hydrate, which is similar to Na-montmorillonite. However, the interlayer sodium ions in rectorite show an asymmetrical distribution quite different from the symmetrical distribution in montmorillonite. Because of unequal layer charges between the smectite part and illite part of retorite, sodium ions prefer to distribute close to the illite part surface. PMID:25625308

Zhou, Jinhong; Boek, Edo S; Zhu, Jianxi; Lu, Xiancai; Sprik, Michiel; He, Hongping

2015-02-17

424

Coulomb excitation of the proton-dripline nucleus Na20  

NASA Astrophysics Data System (ADS)

The low-energy structure of the proton dripline nucleus Na20 has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV/nucleon Na20 beam of ~5106 ions/s was Coulomb excited by a 0.5-mg/cm2natTi target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while ? rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2+ ground state to the first excited 3+ and 4+ states was observed, and B(?L) values were determined using the 2+?0+ de-excitation in Ti48 as a reference. The resulting B(?L)? values are B(E2;3+?2+)=556e2fm4 (17.01.9 W.u.), B(E2;4+?2+)=35.75.7e2fm4 (11.11.8 W.u.), and B(M1;4+?3+)=0.1540.030?N2 (0.0860.017 W.u.). These measurements provide the first experimental determination of B(?L) values for this proton dripline nucleus of astrophysical interest.

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C. J.; 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.

2009-10-01

425

Photophysical properties of metal ion functionalized NaY zeolite.  

PubMed

A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu(3+), Tb(3+), Ce(3+), Y(3+), Zn(2+), Cd(2+), Cu(2+)) exchanged zeolite, rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Y(3+) and rare-earth ion (Eu(3+), Tb(3+), Ce(3+)) exchanged zeolite modified with Zn(2+) are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare-earth ion broadens the application of zeolite as a luminescent host. The Eu(3+) ion exchanged zeolite shows white light luminescence with a great application value and Ce(3+) exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite. PMID:24392790

Duan, Tian-Wei; Yan, Bing

2014-01-01

426

Iron oxide nanoparticles in NaA zeolite cages  

NASA Astrophysics Data System (ADS)

Zeolite NaA samples with varying concentration of Fe3+ ions have been prepared by wet chemical method. Based on powder X-ray diffraction, 29Si and 27Al MAS NMR and Fe3+ EPR investigations, the formation of nano-sized ferric oxide particles inside the larger ?-cages of zeolite NaA has been established. Both Mssbauer effect and magnetization measurements carried out down to 4.5 K established the superparamagnetic behaviour of these Fe2O3 particles with a blocking temperature of ?20 K, where the magnetization values showed deviation for the zero field cooled and field cooled samples and the appearance of a very narrow magnetic hysteresis loop below this temperature. For all Fe3+ containing samples the room temperature Mssbauer spectrum is a broad quadrupole doublet with chemical shift, ? ? 0.33 mm/s and quadrupole splitting, ?Eq ? 0.68 mm/s. Variable temperature 57Fe Mssbauer effect measurements exhibited magnetic features below the blocking temperature and at 4.5 K, the observed spectrum is a broad magnetic sextet characterized by an internal hyperfine field value of ?504 kOe along with a very weak central superparamagnetic quadrupole doublet.

Kulshreshtha, S. K.; Vijayalakshmi, R.; Sudarsan, V.; Salunke, H. G.; Bhargava, S. C.

2013-07-01

427

WNK kinases regulate thiazide-sensitive Na-Cl cotransport.  

PubMed

Pseudohypoaldosteronism type II (PHAII) is an autosomal dominant disorder of hyperkalemia and hypertension. Mutations in two members of the WNK kinase family, WNK1 and WNK4, cause the disease. WNK1 mutations are believed to increase WNK1 expression; the effect of WNK4 mutations remains unknown. The clinical phenotype of PHAII is opposite to Gitelman syndrome, a disease caused by dysfunction of the thiazide-sensitive Na-Cl cotransporter. We tested the hypothesis that WNK kinases regulate the mammalian thiazide-sensitive Na-Cl cotransporter (NCC). Mouse WNK4 was cloned and expressed in Xenopus oocytes with or without NCC. Coexpression with WNK4 suppressed NCC activity by more than 85%. This effect did not result from defects in NCC synthesis or processing, but was associated with an 85% reduction in NCC abundance at the plasma membrane. Unlike WNK4, WNK1 did not affect NCC activity directly. WNK1, however, completely prevented WNK4 inhibition of NCC. Some WNK4 mutations that cause PHAII retained NCC-inhibiting activity, but the Q562E WNK4 demonstrated diminished activity, suggesting that some PHAII mutations lead to loss of NCC inhibition. Gain-of-function WNK1 mutations would be expected to inhibit WNK4 activity, thereby activating NCC, contributing to the PHAII phenotype. Together, these results identify WNK kinases as a previously unrecognized sodium regulatory pathway of the distal nephron. This pathway likely contributes to normal and pathological blood pressure homeostasis. PMID:12671053

Yang, Chao-Ling; Angell, Jordan; Mitchell, Rose; Ellison, David H

2003-04-01

428

MINOS Calibration and NA49 Hadronic Production Studies  

SciTech Connect

An overview of the current status of the Main Injector Neutrino Oscillation Search (MINOS) is presented. MINOS is a long-baseline experiment with two detectors situated in North America. The near detector is based at the emission point of the NuMI beam at Fermilab, Chicago, the far detector is 735 km downstream in a disused iron mine in Soudan, Minnesota. A third detector, the calibration detector, is used to cross-calibrate these detectors by sampling different particle beams at CERN. A detailed description of the design and construction of the light-injection calibration system is included. Also presented are experimental investigations into proton-carbon collisions at 158 GeV/c carried out with the NA49 experiment at CERN. The NA49 experiment is a Time Projection Chamber (TPC) based experiment situated at CERN's North Area. It is a well established experiment with well known characteristics. The data gained from this investigation are to be used to parameterize various hadronic production processes in accelerator and atmospheric neutrino production. These hadronic production parameters will be used to improve the neutrino generation models used in calculating the neutrino oscillation parameters in MINOS.

Morse, Robert James

2003-08-01

429

Involvement of Na+ in Active Uptake of Pyruvate in Mesophyll Chloroplasts of Some C4 Plants 1  

PubMed Central

An artificial Na+ gradient across the envelope (Na+ jump) enhanced pyruvate uptake in the dark into mesophyll chloroplasts of a C4 plant, Panicum miliaceum (NAD-malic enzyme type) (J Ohnishi, R Kanai [1987] FEBS Lett 219:347). In the present study, 22Na+ and pyruvate uptake were examined in mesophyll chloroplasts of several species of C4 plants. Enhancement of pyruvate uptake by a Na+ jump in the dark was also seen in mesophyll chloroplasts of Urochloa panicoides and Panicum maximum (phosphoenolpyruvate carboxykinase types) but not in Zea mays or Sorghum bicolor (NADP-malic enzyme types). In mesophyll chloroplasts of P. miliaceum and P. maximum, pyruvate in turn enhanced Na+ uptake in the dark when added together with Na+. When flux of endogenous Na+ was measured in these mesophyll chloroplasts preincubated with 22Na+, pyruvate addition induced Na+ influx, and the extent of the pyruvate-induced Na+ influx positively correlated with that of pyruvate uptake. A Na+/H+ exchange ionophore, monensin, nullified all the above mutual effects of Na+ and pyruvate in mesophyll chloroplasts of P. miliaceum, while it accelerated Na+ uptake and increased equilibrium level of chloroplast 22Na+. Measurements of initial uptake rates of pyruvate and Na+ gave a stoichiometry close to 1:1. These results point to Na+/pyruvate cotransport into mesophyll chloroplasts of some C4 plants. PMID:16667876

Ohnishi, Jun-ichi; Flgge, Ulf-Ingo; Heldt, Hans W.; Kanai, Ryuzi

1990-01-01

430

A Novel Plant Vacuolar Na /H Antiporter Gene Evolved by DNA Shuffling Confers Improved Salt Tolerance in Yeast*  

E-print Network

cellular ion homeostasis and mediating the trans- port of Na out of the cytosol and into the vacuole and ion homeostasis (1). Because plants lack Na -ATPases, Na homeostasis depends mainly on the expression roles in endosomal pH regulation (5), Na homeostasis, vesicular trafficking, and protein targeting (6

Blumwald, Eduardo

431

Na-A (LTA) zeolite synthesis directly from alumatrane and silatrane by sol-gel microwave techniques  

E-print Network

Na-A (LTA) zeolite synthesis directly from alumatrane and silatrane by sol-gel microwave techniques 2002; accepted 7 August 2002 Abstract Na-A (1 mm crystal size) zeolite was successfully synthesized via large crystallite sizes ($4.5 mm). The analyzed Si:Al:Na ratio of synthe- sized Na-A zeolite is 1

Gulari, Erdogan

432

Perinatal Na+ Overload Programs Raised Renal Proximal Na+ Transport and Enalapril-Sensitive Alterations of Ang II Signaling Pathways during Adulthood  

PubMed Central

Background High Na+ intake is a reality in nowadays and is frequently accompanied by renal and cardiovascular alterations. In this study, renal mechanisms underlying perinatal Na+ overload-programmed alterations in Na+ transporters and the renin/angiotensin system (RAS) were investigated, together with effects of short-term treatment with enalapril in terms of reprogramming molecular alterations in kidney. Methodology/Principal Findings Male adult Wistar rats were obtained from dams maintained throughout pregnancy and lactation on a standard diet and drinking water (control) or 0.17 M NaCl (saline group). Enalapril (100 mg/l), an angiotensin converting enzyme inhibitor, was administered for three weeks after weaning. Ninety day old offspring from dams that drank saline presented with proximal tubules exhibiting increased (Na++K+)ATPase expression and activity. Ouabain-insensitive Na+-ATPase activity remained unchanged but its response to angiotensin II (Ang II) was lost. PKC, PKA, renal thiobarbituric acid reactive substances (TBARS), macrophage infiltration and collagen deposition markedly increased, and AT2 receptor expression decreased while AT1 expression was unaltered. Early treatment with enalapril reduced expression and activity of (Na++K+)ATPase, partially recovered the response of Na+-ATPase to Ang II, and reduced PKC and PKA activities independently of whether offspring were exposed to high perinatal Na+ or not. In addition, treatment with enalapril per se reduced AT2 receptor expression, and increased TBARS, macrophage infiltration and collagen deposition. The perinatally Na+-overloaded offspring presented high numbers of Ang II-positive cortical cells, and significantly lower circulating Ang I, indicating that programming/reprogramming impacted systemic and local RAS. Conclusions/Significance Maternal Na+ overload programmed alterations in renal Na+ transporters and in its regulation, as well as severe structural lesions in adult offspring. Enalapril was beneficial predominantly through its influence on Na+ pumping activities in adult offspring. However, side effects including down-regulation of PKA, PKC and AT2 receptors and increased TBARS could impair renal function in later life. PMID:22928034

Cabral, Edjair V.; Vieira-Filho, Leucio D.; Silva, Paulo A.; Nascimento, Williams S.; Aires, Regina S.; Oliveira, Fabiana S. T.; Luzardo, Ricardo; Vieyra, Adalberto; Paixo, Ana D. O.

2012-01-01