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1

PAPEL DO EXERCÍCIO FÍSICO NA DISFUNÇÃO ENDOTELIAL DE PACIENTES COM SÍNDROME METABÓLICA E DIABETES MELLITUS The role of physical exercise in endothelial dysfunction of patients with Metabolic Syndrome and Diabetes Mellitus  

Microsoft Academic Search

RESUMO Pacientes com síndrome metabólica e diabetes mellitus têm morbidade e mortalidade cardiovascular aumentada. A disfunção endotelial tem sido implicada na patogênese da doença vascular diabética. Essa função anormal ocorre precocemente antes da manifestação da doença cardiovascular, caracterizando-se por redução do vasorelaxamento dependente do endotélio. Neste sentido, intervenções com a L-arginina, drogas de redução lipídicas (estatinas), antioxidantes (vitamina C) e

Carlos Alberto da Silva; José Carlos Grando

2

The FASES instrument development and experiment preparation for the ISS  

NASA Astrophysics Data System (ADS)

The FASES experiments target the investigation of the stability of emulsions. The main objec-tives are the study of the surfactant adsorption at the liquid / liquid interfaces, the interaction of the droplets as well as the behaviour of the liquid film between nearby drops. Particular focus is given to the dynamic droplet evolution during emulsion destabilisation. The results of the experiments shall support development of methods for the modelling of droplet size distri-butions, which are important to many industries using stable emulsions like food production, cosmetics and pharmaceutics or unstable emulsions as required for applications in waste water treatment or crude oil recovery. The development of the experimental instrumentation was initiated in 2002. The flight instru-ment hardware development was started in 2004 and finally the flight unit was completed in 2009. Currently the final flight preparation is proceeding targeting a launch to the International Space Station (ISS) with Progress 39P in September 2010. The experiment setup of the instrument is accommodated in a box type insert called Experiment Container (EC), which will be installed in the Fluid Science Laboratory part of the European Columbus module of the ISS. The EC is composed of two diagnostics instruments for the investigation of transparent and opaque liquid emulsion. The transparent emulsions will be subject to the experiment called "Investigations on drop/drop interactions in Transparent Emulsions" (ITEM). The opaque emulsion samples will be studied in the experiment called "Investigations on concentrated or opaque Emulsions and on Phase Inversions" (EMPI). The thermal conditioning unit (TCU) allows performing homogeneous thermalization, tem-perature sweeps, emulsion preparation by stirrer, and optical diagnostics with a scanning mi-croscope. The objective of the instrument is the 3D reconstruction of the emulsion droplet distribution in the liquid matrix in terms of the droplet sizes, location and their time depen-dent evolution. The TCU will be used for the stability experiment ITEM-S and the droplet freezing experiment ITEM-F. The Differential Scanning Calorimeter (DSC) will give an information about the evolution of the emulsion through the droplet size distribution and the dispersion state of the droplets within the emulsion during a controlled temperature sweep by measuring the latent heat of droplet freezing and melting during the EMPI experiments. For this purpose the calorimeter is equipped with a reference sample filled with a pure liquid matrix and a similar measurement sample filled with the specific emulsion under investigation. The differential heat flux between measurement sample and reference sample is measured with a sensitive heat flux sensor. Each instrument is serviced by a robotic sample stowage system, which accommodates in total 44 different ITEM and EMPI emulsion samples each filled with a specific composition of the emulsion. Currently the flight preparation is ongoing with particular focus on the preparation of the emulsion flight sample set and the instrument's operating parameters. The FASES flight instrument was developed by ASTRIUM Space Transportation Germany with support of RUAG Aerospace Wallisellen under ESA / ESTEC contract. The science team of FASES is supported by ESA/ESTEC (Microgravity Application Programme, AO99-052).

Picker, Gerold; Gollinger, Klaus; Greger, Ralf; Dettmann, Jan; Winter, Josef; Dewandre, Thierry; Castiglione, Luigi; Vincent-Bonnieu, Sebastien; Liggieri, Libero; Clausse, Daniele; Antoni, Mickael

3

EDITAL 003/POSJOR/2013 RESULTADO DA PRIMEIRA FASE DA SELEO 2013  

E-print Network

FILHO 4. CAMILE CARVALHO NASCIMENTO 5. CLAUDIA DE CONTO 6. DANIELA DE OLIVEIRA SOARES 7. DANIELLE ANTONIO NEIVA 24. S�NIA REGINA DA SILVA 25. TÁSSIA BECKER ALEXANDRE 26. THIAGO AMORIM CAMINADA 27 para a arguição da Terceira Fase: TER�A-FEIRA, DIA 21/05/2013 SALA 141 CLAUDIA DE CONTO Das 14h às 14h

Floeter, Sergio Ricardo

4

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 Grosbøl et al. (2012).

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

2012-09-01

5

Comunicantes domiciliares jovens de pacientes com TB pulmonar na região da grande Vitória (ES): um estudo de coorte* Juvenile household contacts aged 15 or younger of patients with pulmonary TB in the greater metropolitan area of Vitória, Brazil: a cohort study  

Microsoft Academic Search

Resumo Objetivo: Comparar aspectos clínicos, radiológicos e laboratoriais de contatos domiciliares, menores de 15 anos, de pacientes com cultura positiva para Mycobacterium tuberculosis. Métodos: Realizou-se um estudo de coorte comparando crianças e adolescentes (? 15 anos) que eram contatos domiciliares de casos de TB com baciloscopia e cultura positiva (grupo exposto, n = 100) ou com baciloscopia negativa e cultura

Ethel Leonor; Noia Maciel; Luiza Werner; Heringer Vieira; Lucília Pereira Dutra Molina; Rosana Alves; Reynaldo Dietze

2009-01-01

6

Los Derechos de los Pacientes del Centro Clnico  

E-print Network

Los Derechos de los Pacientes del Centro Clínico Los Derechos de los Pacientes del Centro Clínico medir las respuestas de los pacientes al tratamiento. Existen procesos que protegen los derechos de paciente que se observen los derechos fundamentales de la dignidad humana. Esta Declaración de Derechos

7

RELACIÓN MÉDICO PACIENTE: DERECHOS DEL ADULTO MAYOR  

PubMed Central

Existen prejuicios en relación con la vejez, incluso entre los profesionales que se dedican a la gerontología. Uno común y peligroso es considerar que los viejos son todos enfermos o discapacitados. La relación médico-paciente es la piedra angular de la práctica y ética médicas. Para alcanzar el respeto por los adultos mayores es necesaria una medicina prudente, basada en una práctica en la cual la reflexión ética y clínica pueda contribuir. Esto último 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; Rodríguez, Eduardo; Lama, Alexis

2009-01-01

8

Seguridad del paciente en los estudios clínicos  

Cancer.gov

Información para pacientes, sus familiares y amigos, y el público en general, sobre cómo se protegen los derechos y la seguridad de las personas que participan en estudios clínicos. Conozca sobre el consentimiento formal, los consejos institucionales de revisión (IRB) y cómo se realiza la vigilancia continua de los estudios.

9

Estudo sobre qualidade de vida com pacientes pós-TMO: aplicação do questionário WHOQOL-Bref Study on quality of life of post-BMT patients: application of WHOQOL-Bref questionnaire Estudio de la calidad de vida de pacientes de post-TMO: aplicación del cuestionario WHOQOL-Bref  

Microsoft Academic Search

RESuMO: O presente trabalho teve por objetivo avaliar a qualidade de vida de pacientes submetidos ao transplante de medula óssea utilizando-se um questionário de avaliação de qualidade de vida, e refletir sobre as contribuições deste instrumento para a compreensão do impacto da doença na vida destes sujeitos, bem como a utilidade destes indicadores para formular e fundamentar o raciocínio clínico

Maria da Conceição dos Santos; Fernanda de Castro Ferreira; Silva Moreira; Marina Ribeiro Rodrigues

10

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

11

Familiares a cargo de pacientes de cáncer (PDQ®)  

Cancer.gov

Sumario informativo revisado por expertos acerca de los desafíos que enfrentan los familiares a cargo de los pacientes con cáncer. Este resumen se centra en las funciones típicas y las inquietudes de las personas a cargo del paciente y en las intervenciones útiles para esas personas.

12

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

13

PROPOSTA DE UM PROTOCOLO PARA O ATENDIMENTO ODONTOLÓGICO DO PACIENTE DIABÉTICO NA ATENÇÃO BÁSICA  

Microsoft Academic Search

Diabetes melittus is an actual serious problem of health. It includes all of social classes, and requests, of public health focal point, a multidisciplinary approach. Its debilitating and degenerative characteristic, its interference in the way of life of the porter, as well as their interactions with other local and systemic conditions become this desease a priority in program of basic

Francisco Rodrigues Maia

14

Achados na vestibulometria de pacientes com Vertigem Posicional Paroxística Benigna submetidos à Manobra de Epley  

Microsoft Academic Search

Purpose:To identify the electronystagmographic fi ndings in patients with benign paroxysmal positional vertigo (BPPV) and to evaluate the effectiveness of the particle reposition- ing maneuver in the treatment of BPPV. Method: Sixty-one patients with BPPV underwent a vestibular examination and were treated with particle repositioning maneuver in the Neu- rotological Ambulatory of the Department of Otolaryngology of Irmandade da Santa

Flávia Salvaterra Cusin; Samantha Mattos Rozendo; Cristina Freitas Ganança

2006-01-01

15

NA57 main results  

E-print Network

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

G. E. Bruno; for the NA57 Collaboration

2007-10-15

16

Results from NA49  

E-print Network

An overview of results from the CERN experiment NA49 is presented with emphasis on most recent measurements. NA49 has systematically studied the dependence of hadron production on energy and system size or centrality. At top-SPS energy the detailed investigation of hadron production, now also extending to elliptic flow of Lambda-baryons and to identified particle yields at high p_t, shows that the created matter behaves in a similar manner as at RHIC energies. In the lower SPS energy range a distinct structure is observed in the energy dependence of the rate of strangeness production and in the slopes of p_t-spectra suggesting the onset of the creation of a deconfined phase of matter.

C. Hoehne

2005-10-17

17

Visión Estereo para Posicionamiento de Pacientes en Radioterapia  

Microsoft Academic Search

Resumen— Durante la radioterapia se administran dosis tumoricidas con el fin de eliminar las células cancerosas. Una vez que se ha determinado la\\/las regiones a irradiar, se debe tener especial cuidado en el posicionamiento del paciente en el acelerador lineal y su posterior re-posicionamiento de modo tal que la zona bajo tratamiento sea siempre la misma, minimizando el daño al

Arnulfo Ortiz Torres; Andrés Valdez; Guillermo Alvarez

18

Na Cauda do Cometa  

NASA Astrophysics Data System (ADS)

Quando viam um cometa, os antigos gregos imaginavam uma estrela com uma vasta cabeleira. Não à toa, a palavra deriva do termo koma, que significa cabelo. Constituídos por fragmentos de gelo e gases, os cometas possuem um núcleo sólido, que pode ter vários quilômetros de diâmetro, e uma cauda que sempre aponta na direção contrária ao Sol, devido aos ventos solares. Graças à aparência de pontos luminosos em movimento (ao contrário de outros astros, que parecem estáticos), esses corpos celestes foram interpretados por diferentes povos com muito misticismo, inspirando mitos tanto de boas-novas como de maus presságios. Conheça algumas dessas histórias:

Voelzke, M. R.

2009-01-01

19

Recent Results from NA35  

NASA Astrophysics Data System (ADS)

Recent results on hadron production in central nucleus-nucleus collisions obtained by the experiment NA35 at the CERN SPS are reviewed. The first preliminary results on central Pb+Pb collisions obtained by the NA49 experiment, the successor of NA35, are also discussed. Their impact on our understanding of the properties of strongly interacting matter at different stages of the collision is underlined.

Ga?dzicki, Marek; Alber, T.; Appelshäuser, H.; Bächler, J.; Bartke, J.; Bialkowska, H.; Bloomer, M. A.; Bock, R.; Braithwaite, W. J.; Brinkmann, D.; Brockmann, R.; Bun?i?, P.; Chan, P.; Cramer, J. G.; Cramer, P. B.; Derado, I.; Eckardt, V.; Eschke, J.; Favuzzi, C.; Ferenc, D.; Fleischmann, B.; Foka, P.; Fuchs, M.; Ga?dzicki, M.; Gladysz, E.; Günther, J.; Harris, J. W.; Hoffmann, M.; Jacobs, P.; Kabana, S.; Kadija, K.; Kosiec, J.; Kowalski, M.; Kühmichel, A.; Lee, J. Y.; Ljubi?i?, A.; Margetis, S.; Mitchell, J. T.; Morse, R.; Nappi, E.; Odyniec, G.; Pai?, G.; Panagiotou, A. D.; Petridis, A.; Piper, A.; Posa, F.; Poskanzer, A. M.; Pühlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Röhrich, D.; Roland, G.; Rothard, H.; Runge, K.; Sandoval, A.; Schmitz, N.; Schmoetten, E.; Sendelbach, R.; Seyboth, P.; Seyerlein, J.; Skrzypczak, E.; Spinelli, P.; Stefa?ski, P.; Stock, R.; Ströbele, H.; Trainor, T. A.; Vasileiadis, G.; Vassiliou, M.; Vranic, D.; Wenig, S.; Wosiek, B.; Zhu, X.; NA35 Collaboration

1995-02-01

20

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.

21

Quimioterapia de alta dosis prolonga en forma significativa la supervivencia en pacientes con leucemia mieloide aguda  

Cancer.gov

Los resultados preliminares de un estudio clínico grande con asignación al azar de pacientes de 16 a 60 años de edad con leucemia mieloide aguda (LMA), un cáncer de la sangre y de la médula ósea, que no había sido tratada anteriormente, muestran que los pacientes que recibieron una alta dosis de daunorrubicina, un fármaco de quimioterapia disponible comercialmente, durante la terapia inicial vivieron más que los pacientes que recibieron una dosis normal del mismo fármaco.

22

Na+ recirculation and isosmotic transport.  

PubMed

The Na(+) recirculation theory for solute-coupled fluid absorption is an expansion of the local osmosis concept introduced by Curran and analyzed by Diamond & Bossert. Based on studies on small intestine the theory assumes that the observed recirculation of Na(+) serves regulation of the osmolarity of the absorbate. Mathematical modeling reproducing bioelectric and hydrosmotic properties of small intestine and proximal tubule, respectively, predicts a significant range of observations such as isosmotic transport, hyposmotic transport, solvent drag, anomalous solvent drag, the residual hydraulic permeability in proximal tubule of AQP1 (-/-) mice, and the inverse relationship between hydraulic permeability and the concentration difference needed to reverse transepithelial water flow. The model reproduces the volume responses of cells and lateral intercellular space (lis) following replacement of luminal NaCl by sucrose as well as the linear dependence of volume absorption on luminal NaCl concentration. Analysis of solvent drag on Na(+) in tight junctions provides explanation for the surprisingly high metabolic efficiency of Na(+) reabsorption. The model predicts and explains low metabolic efficiency in diluted external baths. Hyperosmolarity of lis is governed by the hydraulic permeability of the apical plasma membrane and tight junction with 6-7 mOsm in small intestine and < or = 1 mOsm in proximal tubule. Truly isosmotic transport demands a Na(+) recirculation of 50-70% in small intestine but might be barely measurable in proximal tubule. The model fails to reproduce a certain type of observations: The reduced volume absorption at transepithelial osmotic equilibrium in AQP1 knockout mice, and the stimulated water absorption by gallbladder in diluted external solutions. Thus, it indicates cellular regulation of apical Na(+) uptake, which is not included in the mathematical treatment. PMID:17206513

Larsen, E H; Møbjerg, N

2006-01-01

23

Desenvolvimento, aplicação e avaliação de um modelo de intervenção positiva para pacientes com miastenia gravis.  

E-print Network

??Essa dissertação objetiva desenvolver, aplicar e avaliar um modelo de intervenção psicológica em grupo baseado nas abordagens cognitivo-comportamental e positiva para pacientes com miastenia gravis.… (more)

Bruna Larissa Seibel

2012-01-01

24

O IMPACTO DE UM PROGRAMA DE ATIVIDADE FÍSICA NA QUALIDADE DE VIDA DE PACIENTES COM DOENÇA DE PARKINSON  

Microsoft Academic Search

Impact of a physical activity program on quality of life among Parkinson's disease patients Background: Parkinson's Disease (PD) is a chronic degenerative disease of the central nervous system that affects one in 1,000 individuals over 65 years old and one in 100 over 75 years. PD patients present bradykinesia, tremor, rigidity, decreased muscle strength and physical capacity, cognitive dysfunctions and

L. Teixeira-Salmela

2005-01-01

25

Drugs preventing Na+ and Ca2+ overload.  

PubMed

Cardiac intracellular Na+and Ca2+homeostasis is regulated by the concerted action of ion channels, pumps and exchangers. The Na+, K+-ATPase produces the electrochemical concentration gradient for Na+, which is the driving force for Ca2+removal from the cytosol via the Na+/Ca2+exchange. Reduction of this gradient by increased intracellular Na+concentration leads to cellular Ca2+overload resulting in arrhythmias and contractile dysfunction. Na+and Ca2+overload-associated arrhythmias can be produced experimentally by inhibition of Na+efflux (digitalis-induced intoxication) and by abnormal Na+influx via modulated Na+channels (veratridine, DPI 201-106; hypoxia) or via the Na+, H+exchanger. Theoretically, blockers of Na+and Ca2+channels, inhibitors of abnormal oscillatory release of Ca2+from internal stores or modulators of the Na+, Ca2+and Na+, H+exchanger activities could protect against cellular Na+and Ca2+overload. Three exemplary drugs that prevent Na+and Ca2+overload, i.e. the benzothiazolamine R56865, the methylenephenoxydioxy-derivative CP-060S, and the benzoyl-guanidine Hoe 642, a Na+, H+exchange blocker, are briefly reviewed with respect to their efficacy on digitalis-, veratridine- and ischaemia/reperfusion-induced arrhythmias. PMID:10094840

Ravens, U; Himmel, H M

1999-03-01

26

Direct Measurement of ^21Na+? Stellar Reaction  

NASA Astrophysics Data System (ADS)

Nucleosynthesis of ^22Na is an interesting subject because of possible ?-ray observation and isotopic anomalies in presolar grain. ^22Na would have been mainly produced in the NeNa cycle. At high temperature conditions, ^21Na(?,p)^24Mg reaction could play a significant role to make flow from the NeNa cycle to the next MgAl cycle and beyond. Clearly, the ^21Na(?,p)^24Mg stellar reaction would bypass ^22Na, resulting in reduction of ^22Na production, therefore, it is strongly coupled to the Ne-E problem. It could be also important to understand the early stage of the rp-process. Experiment was performed using a 39 MeV ^21Na radioactive beam obtained by the CNS Radio Isotope Beam separator CRIB of the University of Tokyo. Both protons and alphas were measured from ?+^21Na scattering with a thick ^4He gas target.

Binh Dam, Nguyen; Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Hashimoto, T.; Kahl, D.; Kubono, S.; Le, H. K.; Nguyen, T. T.; Iwasa, N.; Kume, N.; Kato, S.; Teranishi, T.

2009-10-01

27

Familiares a cargo de pacientes de cáncer: funciones y desafíos (PDQ®)  

Cancer.gov

Sumario informativo revisado por expertos acerca de los desafíos que enfrentan los familiares a cargo de los pacientes con cáncer. Este resumen se centra en las funciones típicas y las inquietudes de las personas a cargo del paciente y en las intervenciones útiles para esas personas.

28

Impacto de las redes sociales de pacientes en la práctica 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 específicos de salud la oportunidad de compartir experiencias, buscar, recibir y proveer información, consejos e incluso apoyo emocional online. Pero, ¿cuál es el impacto de estas redes en

Elena Torrente; Joan Escarrabill; Tino Martí

2010-01-01

29

Autorizacin para divulgar informacin mdica Nombre del paciente: ________________________________ Fecha de nacimiento: ______________  

E-print Network

) HIPAA Compliance / Columbia University Medical Center 630 West 168th Street, Box 159 New York, NY 10032, salud mental o psiquiatría pueden tener requisitos de conformidad adicionales que se deben cumplir antes paciente y entregue una copia al paciente. Health Insurance Portability and Accountability Act (HIPAA

Columbia University

30

Photoelectron imaging spectroscopy of the small sodium cluster anions Na3(-), Na5(-), and Na7(-).  

PubMed

We present a photoelectron imaging study of the small sodium cluster anions Na3(-), Na5(-), and Na7(-) at photon energies in the visible and near UV range (hv = 1.64-4.28 eV). The resulting angular distributions are remarkably diverse and exhibit a strong dependence on photon energy; only for hv > 3.5 eV do they evolve into more uniform distributions peaked in the direction of the laser polarization. We show that different energy dependencies of the distributions are related to different angular-momentum characters of the bound states. The jellium s-like character of the lowest single-particle states results in photoelectron emission parallel to the laser polarization at all photon energies, whereas the p-like character of the higher states leads to essentially isotropic distributions at threshold and a strong variation with photon energy. Close to the detachment threshold, the asymptotic angular distributions are attributed to the approximate validity of Wigner's law, which states that the spectrum is dominated by the partial wave with the smallest angular momentum. For the planar cluster Na5(-), we observe characteristically different behavior for electrons detached from the two in-plane p-like states, and we show how this correlates with the molecular symmetry. Our results indicate that a simple jellium-like description of the molecular orbitals is appropriate for the three-dimensional cluster Na7(-), despite the energetic splitting of the normally triply degenerate 1p level. PMID:24617832

Bartels, Christof; Hock, Christian; Kuhnen, Raphael; Issendorff, Bernd v

2014-09-18

31

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

32

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

33

Na+ Tolerance and Na+ Transport in Higher Plants  

PubMed Central

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

TESTER, MARK; DAVENPORT, ROMOLA

2003-01-01

34

Effects of Na and K ions on the active Na transport in guinea-pig auricles.  

PubMed

1. The effect of Na and K ions on active Na transport was studied in guinea-pig auricles by means of flame photometry. 2. The Na influx into preparations rewarmed in Tyrode's solution after cooling was estimated to be about 1.05 mmole/l fibre water - min (l.f.w.-min) or c. 8 pmole/cm2 - s. Intracellular Na ions enhanced the active Na efflux over a wide range of concentrations. A decrease in the extracellular Na concentration ([Na]o) had no major effect on the active Na efflux. 3. Extracellular K ions initiated an active Na efflux from rewarmed auricles with an elevated [Na[i over a narrow range of K concentrations ([K]o). 4. Assuming Michaelis-Menten kinetics the maximal active Na efflux activated by internal Na ions was calculated to be about 4 mmole/l.f.w. - min (30 pmole/cm2 - s). Half maximal Na efflux occurred at about 22 mmole/l.f.w. [Na]i. The maximal K-activated active - min (28 pmole/cm2 - s) and was half maximal at a [K]o of about 0.2 mM. 5. It is tentatively concluded that the maximal active Na efflux from guinea-pig atria is 3--4 times larger than the physiological flux. Under normal conditions active Na efflux in heart is mainly regulated by variations of [Na]i. PMID:988542

Glitsch, H G; Pusch, H; Venetz, K

1976-09-01

35

Aithisg Bhliadhnail Coilltearachd na h-Alba  

E-print Network

Aithisg Bhliadhnail �ghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail 2007-2008 #12;�ghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail 2007-08 1 | �ghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail Chuairt Alba 22 Pàipearan-taice 26 #12;2 | �ghdarras Coilltearachd na h-Alba Lèirmheas Bliadhnail 2007

36

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

PubMed Central

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

2013-01-01

37

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

Cancer.gov

Los resultados preliminares de un estudio clínico 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 estómago o en el intestino delgado, demostraron que los pacientes a los que se administró mesilato de imatinib (Gleevec®) luego de la extirpación total de su tumor tuvieron una probabilidad significativamente menor de padecer una recidiva del cáncer en comparación con aquellos a los que no se administró imatinib.

38

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

Fábry, Jan; Havlák, Lubomír; Ku?eráková, Monika; Dušek, Michal

2014-06-15

39

Maintaining the Na atmosphere of Mercury  

NASA Technical Reports Server (NTRS)

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

Killen, Rosemary M.; Morgan, Thomas H.

1993-01-01

40

Maintaining the NA atmosphere of Mercury  

NASA Astrophysics Data System (ADS)

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

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

1993-02-01

41

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

42

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

Microsoft Academic Search

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

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

2004-01-01

43

Na+ imaging reveals little difference in action potential–evoked Na+ influx between axon and soma  

Microsoft Academic Search

In cortical pyramidal neurons, the axon initial segment (AIS) is pivotal in synaptic integration. It has been asserted that this is because there is a high density of Na+ channels in the AIS. However, we found that action potential–associated Na+ flux, as measured by high-speed fluorescence Na+ imaging, was about threefold larger in the rat AIS than in the soma.

Nechama Lasser-Ross; Michael J Gutnick; William N Ross; Ilya A Fleidervish

2010-01-01

44

AMPLIANDO A NOÇÃO DE CONTEXTO NA LINGÜÍSTICA SISTÊMICO-FUNCIONAL E NA ANÁLISE CRÍTICA DO DISCURSO  

Microsoft Academic Search

Resumo: Apesar de todos os avanços realizados por pesquisadores na Lingüística Sistêmico-Funcional (LSF) e na Análise Crítica do Discurso (ACD) na descrição da estreita relação entre a linguagem e o contexto social, verifica-se ainda a necessidade de teorizações mais amplas sobre essa questão. Neste artigo exploro aspectos da teoria da estruturação de Giddens como ferramentas para a análise de contexto

J. L. Meurer

45

Na+-H+ exchange and Na+ entry across the apical membrane of Necturus gallbladder  

PubMed Central

The role of Na+-H+ exchange in Na+ transport across the apical membrane was evaluated in Necturus gallbladder epithelium by means of intracellular Na+ activity (aNai) and 22Na+ uptake measurements. Under control conditions, complete replacement of Na+ in the mucosal solution with tetramethylammonium reduced aNai from 14.0 to 6.9 mM in 2 min (P less than 0.001). Mucosal addition of the Na+-H+ exchange inhibitor amiloride (10(-3) M) reduced aNai from 15.0 to 13.3 mM (P less than 0.001), whereas bumetanide (10(-5) and 10(-4) M) had no effect. Na+ influx across the apical membrane was studied by treating the tissues with ouabain, bathing them in Na-free solutions, and suddenly replacing the mucosal solution with an Na-containing solution. When the mucosal solution was replaced with Na-Ringer's, aNai increased at approximately 11 mM/min. This increase was inhibited by 54% by amiloride (10(-3) M, P less than 0.001) and was unaffected by bumetanide (10(-5) M). Amiloride- inhibitable Na+ fluxes across the apical membrane were also induced by the imposition of pH gradients. Na+ influx was also examined in tissues that had not been treated with ouabain. Under control conditions, 22Na+ influx from the mucosal solution into the epithelium was linear over the first 60 s and was inhibited by 40% by amiloride (10(-3) M, P less than 0.001) and by 19% by bumetanide (10(-5) M, P less than 0.025). We conclude that Na+-H+ exchange is a major pathway for Na+ entry in Necturus gallbladder, which accounts for at least half of apical Na+ influx both under transporting conditions and during exposure to ouabain. Bumetanide-inhibitable Na+ entry mechanisms may account for only a smaller fraction of Na+ influx under transporting conditions, and cannot explain influx in ouabain-treated tissues. These results support the hypothesis that NaCl entry results primarily from the operation of parallel Na+-H+ and Cl--HCO-3 exchangers, and not from a bumetanide-inhibitable NaCl cotransporter. PMID:6319545

1984-01-01

46

Regulation of Na(+) fluxes in plants.  

PubMed

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 Ca(2+), 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

47

Polarization dependence of Na/emph>+Na/emph> associative ionization revisited  

NASA Astrophysics Data System (ADS)

The dependence of the associative ionization process Na 3 2P3/2+Na 3 2P3/2-->Na2 ++e- on the polarization of the laser light used for Na excitation was independently investigated in Utrecht and Berlin. The purpose of this paper is to clarify discrepancies between earlier experimental results of Kircz, Morgenstern, and Nienhuis, on one hand, and Rothe, Theyunni, Reck, and Tung on the other hand. The new results confirm in general the data of Kircz, Morgenstern, and Nienhuis, and also indicate a dependence of the anisotropy ratios on the relative velocity of the interacting Na* atoms.

Meijer, H. A. J.; Meulen, H. P. V. D.; Morgenstern, R.; Hertel, I. V.; Meyer, E.; Schmidt, H.; Witte, R.

1986-02-01

48

Crystal structure of Na+, K(+)-ATPase in the Na(+)-bound state.  

PubMed

The Na(+), K(+)-adenosine triphosphatase (ATPase) maintains the electrochemical gradients of Na(+) and K(+) across the plasma membrane--a prerequisite for electrical excitability and secondary transport. Hitherto, structural information has been limited to K(+)-bound or ouabain-blocked forms. We present the crystal structure of a Na(+)-bound Na(+), K(+)-ATPase as determined at 4.3 Å resolution. Compared with the K(+)-bound form, large conformational changes are observed in the ? subunit whereas the ? and ? subunit structures are maintained. The locations of the three Na(+) sites are indicated with the unique site III at the recently suggested IIIb, as further supported by electrophysiological studies on leak currents. Extracellular release of the third Na(+) from IIIb through IIIa, followed by exchange of Na(+) for K(+) at sites I and II, is suggested. PMID:24051246

Nyblom, Maria; Poulsen, Hanne; Gourdon, Pontus; Reinhard, Linda; Andersson, Magnus; Lindahl, Erik; Fedosova, Natalya; Nissen, Poul

2013-10-01

49

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.

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

2014-01-01

50

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

51

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

52

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

2013-11-01

53

Characterisation of sodium cations in dehydrated zeolite NaX by 23Na NMR spectroscopy  

Microsoft Academic Search

23Na MAS, 2D nutation MAS, and DOR NMR spectroscopy has been applied to characterise the location of sodium cations in dehydrated zeolite NaX (Si\\/Al = 1.23). The 23Na MAS NMR spectra recorded at three different magnetic field strengths were decomposed by computer simulation into five lines, which were attributed to five crystallographically distinct cation sites known from X-ray diffraction studies.

M. Feuerstein; M. Hunger; G. Engelhardt; J. P. Amoureux

1996-01-01

54

Autoanticorpos órgão-específicos e sistêmicos em pacientes com lúpus eritematoso sistêmico juvenil e dermatomiosite juvenil.  

E-print Network

??Objetivo: Ao nosso conhecimento, não há estudos na literatura avaliando simultaneamente um grande número de autoanticorpos órgãoespecíficos, bem como a prevalência de doenças autoimunes órgãoespecíficas… (more)

Nádia Emi Aikawa

2011-01-01

55

NaI(Tl) electron energy resolution  

NASA Astrophysics Data System (ADS)

NaI(Tl) electron energy resolution ?e was measured using the Modified Compton Coincidence Technique (MCCT). The MCCT allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662 keV gamma rays within a primary NaI(Tl) detector. Scattered gamma rays were detected using a secondary HPGe detector in a coincidence mode. Measurements were carried out for electron energies ranging from 16 to 438 keV, by varying the scattering angle. Measured HPGe coincidence spectra were deconvolved to determine the scattered energy spectra from the NaI(Tl) detector. Subsequently, the NaI(Tl) electron energy spectra were determined by subtracting the energy of scattered spectra from the incident source energy (662 keV). Using chi-squared minimization, iterative deconvolution of the internal electron energy spectra from the measured NaI(Tl) spectra was then used to determine ?e at the electron energy of interest. ?e values determined using this technique represent variations in light production from monoenergetic electrons, light collection at the photomultiplier tube (PMT) photocathode, photoelectron production, photoelectron collection at the first dynode, and PMT gain, as well as noise from the accompanying electronics. It has been found that the electron energy resolution varies from 24.8% at 16 keV to 6.7% at 438 keV. Results from this study can be used to verify the significance of the different contributions to intrinsic energy resolution.

Mengesha, W.; Valentine, J. D.

2002-06-01

56

Interaction of NaCl(g) and HCl(g) with condensed NA2SO4  

NASA Technical Reports Server (NTRS)

The interaction of Na2SO4(l) with NaCl(g), HCl(g) and H2O(g) was studied in atmospheric pressure flowing air and oxygen at Na2SO4(l) temperatures of 900 and 1000 C. Thermomicrogravimetric and high pressure mass spectrometric sampling techniques were used. Experimental results establish that previously reported enhanced rates of weight loss of Na2SO4(l) in the presence of NaCl(g) are due to the reaction: Na2SO4(c) + 2HCl(g) = 2NaCl(g) + SO2(g) + H2O(g) + 1/2O2(g) being driven to the right in flowing gas systems. The HCl(g) is the product of hydrolysis of NaCl caused by small but significant amounts of H2O(g) present in the system. Thermochemical calculations are used to show that even with sub-ppm levels of H2O(g) present, significant quantities of HCl(g) are produced.

Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.; Miller, R. A.

1977-01-01

57

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.

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

2014-12-01

58

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.

59

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

PubMed

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

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

1990-11-01

60

El NCI inicia un estudio para evaluar la utilidad de la secuenciación genética para mejorar los resultados en los pacientes  

Cancer.gov

El Instituto Nacional del Cáncer (NCI) lanzará este mes un estudio clínico piloto denominado M-PACT con la finalidad de evaluar si el tratamiento asignado según mutaciones genéticas específicas puede brindar beneficios a pacientes con tumores sólidos metastásicos.

61

Imugenicidade e segurança da vacina contra influenza A H1N1/2009 em pacientes com dermatomiosite juvenil.  

E-print Network

??Objetivos: Avaliar a imunogenicidade e segurança da vacina anti-influenza A/H1N1 2009 em pacientes com dermatomiosite juvenil (DMJ) comparados com controles saudáveis e a possível associação… (more)

Vanessa Ramos Guissa

2013-01-01

62

Structural evolution of the sodium cluster anions Na20--Na57-  

NASA Astrophysics Data System (ADS)

Sodium clusters anions Nan- (n=20-57) have been studied by low-temperature photoelectron spectroscopy (PES) and density-functional theory calculations. The geometrical structures of the clusters were determined by a genetic algorithm search and the optimization of a large number of candidate structures. For most of the sizes the calculated density of states of the lowest-energy structures and the measured photoelectron spectra are in excellent agreement, indicating that the correct ground-state structures were found. In the studied size range the sodium clusters follow a simple growth pattern. From Na20- to Na34- a 19 atom double-icosahedral core is stepwise decorated by a 15 atom equatorial belt. The resulting D5h Na34- is then capped by an anti-Mackay overlayer in the size range Na34- to Na44- . From Na52- to Na55- a Mackay overlayer on a 13 atom icosahedron core is completed. Na56- and Na57- result from the 55 atom icosahedron by incorporation of additional adatoms into the outer Mackay layer. Comparison of the ab initio derived structures with results from jellium or Nilsson models reveal that for sizes below Na40- the overall cluster shapes are rather accurately predicted by these simple free-electron models. For larger sizes the agreement is less good, as here optimum atomic packing plays a stronger role. This is most obvious close to size 55, where the icosahedral shell closing leads to a spherical shape of the cluster, whereas the free-electron models predict significant distortions.

Huber, Bernd; Moseler, Michael; Kostko, Oleg; v. Issendorff, Bernd

2009-12-01

63

Recent results from MoNA-LISA  

NASA Astrophysics Data System (ADS)

Studies of the nuclear properties of nuclei close and even beyond the limits of stability have revealed exotic modes of decay and new structural characteristics. The MoNA-LISA array is used at the National Superconducting Cyclotron Laboratory at Michigan State University to study nuclei along the neutron dripline. In a typical experiment, a radioactive beam is employed to produce the neutron-unbound state of interest. This state/resonance immediately decay into a neutron, which is detected by MoNA-LISA and a remaining charged nucleus detected by the sweeper magnet detector suite. In this talk, new exciting findings from recent MoNA-LISA experiments will be presented. These include the first observation of a dineutron decay from ^16Be, the exploration of the ``south shore'' of the Island of Inversion and the first evidence of the decay of the troubling nucleus ^26O.

Spyrou, Artemisia

2012-03-01

64

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

65

U Gorskome kotaru kao na Strawberry Hillu  

E-print Network

. Poslije toga vratio se u Hr- vatsku još sedamnaest puta. “Nastavljam putovati u Hrvatsku da bih ponovno stekao ono što sam izgubio REPORTAŽE STUDENATA SVEU?ILIŠTA U KANSASU O AMERI?KO?HRVATSKIM UMJETNICIMA IZ KANSAS CITYJA ?2? U Gorskome kotaru kao na... su svi ljudi pozna- vali jedni druge, što je prema Donu bio najbolji dio njegova odrastanja. “Bilo je predivno živjeti tako blizu cijele obitelji”, kaže Don. “Hodao bih glavnom ulicom i susretao ro?ake. Na Hillu su se svi poznavali. Održavale su...

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

2012-07-01

66

Na,K pump stimulation by intracellular Na in isolated, intact sheep cardiac Purkinje fibers  

PubMed Central

Regulation of the Na,K pump in intact cells is strongly associated with the level of intracellular Na+. Experiments were carried out on intact, isolated sheep Purkinje strands at 37 degrees C. Membrane potential (Vm) was measured by an open-tipped glass electrode and intracellular Na+ activity (aNai) was calculated from the voltage difference between an Na+-selective microelectrode (ETH 227) and Vm. In some experiments, intracellular potassium (aiK) or chloride (aCli) was measured by a third separate microelectrode. Strands were loaded by Na,K pump inhibition produced by K+ removal and by increasing Na+ leak by removing Mg++ and lowering free Ca++ to 10(-8) M. Equilibrium with outside levels of Na+ was reached within 30-60 min. During sequential addition of 6 mM Mg++ and reduction of Na+ to 2.4 mM, the cells maintained a stable aNai ranging between 25 and 90 mM and Vm was -30.8 +/- 2.2 mV. The Na,K pump was reactivated with 30 mM Rb+ or K+. Vm increased over 50-60 s to -77.4 +/- 5.9 mV with Rb+ activation and to - 66.0 +/- 7.7 mV with K+ activation. aiNa decreased in both cases to 0.5 +/- 0.2 mM in 5-15 min. The maximum rate of aiNa decline (maximum delta aNai/delta t) was the same with K+ and Rb+ at concentrations greater than 20 mM. The response was abolished by 10(-5) M acetylstrophantidin. Maximum delta aNai/delta t was independent of outside Na+, while aKi was negatively correlated with aNai (aKi = 88.4 - 0.86.aNai). aCli decreased by at most 3 mM during reactivation, which indicates that volume changes did not seriously affect aNai. This model provided a functional isolation of the Na,K pump, so that the relation between the pump rate (delta aNai/delta t) and aiNa could be examined. A Hill plot allowed calculation of Vmax ranging from 5.5 to 27 mM/min, which on average is equal to 25 pmol.cm-2.s-1.K 0.5 was 10.5 +/- 0.6 mM (the aNai that gives delta aNai/delta t = Vmax/2) and n equaled 1.94 +/- 0.13 (the Hill coefficient). These values were not different with K+ or Rb+ as an external activator. The number of ouabain-binding sites equaled 400 pmol.g-1, giving a maximum Na+ turnover of 300 s-1. The Na,K pump in intact Purkinje strands exhibited typical sigmoidal saturation kinetics with regard to aNai as described by the equation upsilon/Vmax = aNai(1.94)/(95.2 + aNai(1.94)). The maximum sensitivity of the Na,K pump to aiNa occurred at approximately 6 mM. PMID:2454287

1988-01-01

67

Characterisation of sodium cations in dehydrated zeolite NaX by 23Na NMR spectroscopy.  

PubMed

23Na MAS, 2D nutation MAS, and DOR NMR spectroscopy has been applied to characterise the location of sodium cations in dehydrated zeolite NaX (Si/Al = 1.23). The 23Na MAS NMR spectra recorded at three different magnetic field strengths were decomposed by computer simulation into five lines, which were attributed to five crystallographically distinct cation sites known from X-ray diffraction studies. The assignments of the lines follow from electric field gradient calculations at the 23Na nuclei applying a simple point charge model based on crystal structure data. A weak Gaussian line at low field (delta iso = -6 ppm) is assigned to sodium cations at site I, two broad quadrupole patterns at the high-field side of the spectra are attributed to site I' (delta iso = -19 ppm, QCC = 5.2 MHz, eta = 0) and site II cations (delta iso = -15 ppm, QCC = 4.6 MHz, eta = 0), and two quadrupolar lines dominating the central region of the spectra originate from Na+ at two different III' sites (delta iso = -13 and -29 ppm, QCC = 2.6 and 1.6 MHz, eta = 0.7 and 0.9, respectively). Na+ ions located on a second I' site could be identified from the DOR NMR spectra. The line assignment is further corroborated by the reasonable agreement of the site occupancies estimated from the line intensities with those determined by X-ray diffraction. In addition, sodium site populations of five dehydrated zeolites NaX and NaY with Si/Al ratios between 1.09 and 4.0 were derived from the 23Na MAS NMR spectra. PMID:8986022

Feuerstein, M; Hunger, M; Engelhardt, G; Amoureux, J P

1996-11-01

68

LOGOS E LÉXIS NA RETÓRICA DE ARISTÓTELES  

Microsoft Academic Search

Meu objetivo é examinar o estatuto do discurso na retórica grega, com ênfase em Aristóteles, tanto da perspectiva do lógos propriamente dito, quanto, principalmente, da léxis (que geralmente se traduz por estilo ou como expressão), elemento que caracteriza, legitima e torna eficazes as diferentes formas de realização de diferentes gêneros - nomeadamente os discursos filosófico (ou, se quisermos, científico), retórico

Jacyntho Lins Brandão

69

Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk  

NASA Astrophysics Data System (ADS)

Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO 2 and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 °C for 2-6 h by changing the SiO 2/Al 2O 3, H 2O/Na 2O and Na 2O/SiO 2 molar ratios of precursors in the two-step process. The surface area and NH 4+-cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m 2/g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m 2/g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of ˜3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously.

Katsuki, Hiroaki; Komarneni, Sridhar

2009-07-01

70

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

71

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

72

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

PubMed Central

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

Wehner, Frank; Tinel, Hanna

1998-01-01

73

Hydrogen sulfide inhibits Na(+) uptake in larval zebrafish, Danio rerio.  

PubMed

The present study investigated the role of hydrogen sulfide (H2S) in regulating Na(+) uptake in larval zebrafish, Danio rerio. Waterborne treatment of larvae at 4 days post-fertilization (dpf) with Na2S or GYY-4137 (chemicals known to generate H2S) significantly reduced Na(+) uptake. Exposure of larvae to water enriched with NaCl (1 mM NaCl) caused a pronounced reduction in Na(+) uptake which was prevented by pharmacological inhibition of cystathionine ?-synthase (CBS) or cystathionine ?-lyase (CSE), two key enzymes involved in the endogenous synthesis of H2S. Furthermore, translational gene knockdown of CSE and CBSb significantly increased the basal rate of Na(+) uptake. Waterborne treatment with Na2S significantly decreased whole-body acid excretion and reduced Na(+) uptake in larval zebrafish preexposed to acidic (pH 4.0) water (a condition shown to promote Na(+) uptake via Na(+)-H(+)-exchanger 3b, NHE3b). However, Na2S did not affect Na(+) uptake in larvae depleted of NHE3b-containing ionocytes (HR cells) after knockdown of transcription factor glial cell missing 2 (gcm2) in which Na(+) uptake occurs predominantly via Na(+)-Cl(-) co-transporter (NCC)-containing cells. These observations suggest that Na(+) uptake via NHE3b, but not NCC, is regulated by H2S. Whole-mount immunohistochemistry demonstrated that ionocytes expressing NHE3b also express CSE. These data suggests a physiologically relevant role of H2S as a mechanism to lower Na(+) uptake in zebrafish larvae, probably through its inhibitory action on NHE3b. PMID:24939700

Kumai, Yusuke; Porteus, Cosima S; Kwong, Raymond W M; Perry, Steve F

2014-06-18

74

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

75

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 75 °C, the measured capacity of Na0.44MnO2 in the IL electrolyte with NaClO4 is as high as 115 mAh g-1 (at 0.05 C), which is close to the theoretical value (121 mAh g-1). Moreover, 85% of this capacity can be retained when the charge-discharge rate is increased to 1 C. These properties are superior to those of a conventional organic electrolyte.

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

76

Análisis de componentes cognoscitivos y psiquiátricos en pacientes con demencia frontotemporal y alzheimer / Analysis of cognitive and psychiatric components in patients with frontotemporal dementia and Alzheimer.  

E-print Network

??Reyes Gavilán, Pablo Alexander (2010) Análisis de componentes cognoscitivos y psiquiátricos en pacientes con demencia frontotemporal y alzheimer / Analysis of cognitive and psychiatric components… (more)

Reyes Gavilán, Pablo Alexander

2010-01-01

77

The two C-terminal tyrosines stabilize occluded Na/K pump conformations containing Na or K ions  

PubMed Central

Interactions of the three transported Na ions with the Na/K pump remain incompletely understood. Na/K pump crystal structures show that the extended C terminus of the Na,K–adenosine triphosphatase (ATPase) ? subunit directly contacts transmembrane helices. Deletion of the last five residues (KETYY in almost all Na/K pumps) markedly lowered the apparent affinity for Na activation of pump phosphorylation from ATP, a reflection of cytoplasmic Na affinity for forming the occluded E1P(Na3) conformation. ATPase assays further suggested that C-terminal truncations also interfere with low affinity Na interactions, which are attributable to extracellular effects. Because extracellular Na ions traverse part of the membrane’s electric field to reach their binding sites in the Na/K pump, their movements generate currents that can be monitored with high resolution. We report here electrical measurements to examine how Na/K pump interactions with extracellular Na ions are influenced by C-terminal truncations. We deleted the last two (YY) or five (KESYY) residues in Xenopus laevis ?1 Na/K pumps made ouabain resistant by either of two kinds of point mutations and measured their currents as 10-mM ouabain–sensitive currents in Xenopus oocytes after silencing endogenous Xenopus Na/K pumps with 1 µM ouabain. We found the low affinity inhibitory influence of extracellular Na on outward Na/K pump current at negative voltages to be impaired in all of the C-terminally truncated pumps. Correspondingly, voltage jump–induced transient charge movements that reflect pump interactions with extracellular Na ions were strongly shifted to more negative potentials; this signals a several-fold reduction of the apparent affinity for extracellular Na in the truncated pumps. Parallel lowering of Na affinity on both sides of the membrane argues that the C-terminal contacts provide important stabilization of the occluded E1P(Na3) conformation, regardless of the route of Na ion entry into the binding pocket. Gating measurements of palytoxin-opened Na/K pump channels additionally imply that the C-terminal contacts also help stabilize pump conformations with occluded K ions. PMID:20548052

Vedovato, Natascia

2010-01-01

78

Na+-driven bacterial flagellar motors.  

PubMed

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

Imae, Y; Atsumi, T

1989-12-01

79

Geant4 Simulation of MoNA  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) is a neutron detector array consisting of 144 plastic scintillator detector modules at the National Superconducting Cyclotron Laboratory (NSCL). The detailed simulation of the neutron interaction with the detector is a crucial tool for optimizing detector configurations and analyzing experimental data. For this purpose the MoNA collaboration is developing a simulation package based on Geant4, a state-of-the-art C++ toolkit for the simulation of the passage of particles through matter. Our work this past summer involved introducing detector geometry into the Geant4 code, as well as determining how the program handles simulations of different physical interactions inside of the detector. By upgrading from Geant3 to Geant4, we are able to better simulate the physics of our experiments.

Fritsch, A.; Heim, M.; Baumann, T.; Mosby, S.; Spyrou, A.

2008-10-01

80

NaI Detector Network at Aragats  

NASA Astrophysics Data System (ADS)

The Aragats Space Environmental Center (ASEC) [1] provides monitoring of different species of secondary cosmic rays and consists of two high altitude research stations on Mt. Aragats in Armenia. Along with solar modulation effects, ASEC detectors register several coherent enhancements associated with thunderstorm activity. The experimental techniques used allowed for the first time to simultaneously measure fluxes of the electrons, muons, gamma rays, and neutrons correlated with thunderstorm activity [2,3]. Ground-based observations by a complex of surface particle detectors, measuring in systematically and repeatable fashion, gamma quanta, electrons, muons and neutrons from atmospheric sources are necessary for proving the theory of particle acceleration and multiplication during thunderstorms. Energy spectra and correlations between fluxes of different particles, measured on Earth's surface address the important issues of research of the solar modulation effects and the atmospheric high-energy phenomena. In May 26 2011, launched 5 NaI(Tl) (thallium-doped sodium iodide) scintillation detectors and 1 plastic one in the new ASEC laboratory on Aragats to detect low energy gamma rays from the thunderclouds and short particle bursts. Including NaI(Tl) detectors in ASEC detectors system is of great importance for investigation thunderstorm phenomena because NaI(Tl) detectors have high efficiency of gamma ray detecting in comparison with plastic ones.

Avakyan, Karen; Arakelyan, Karen; Chilingarian, Ashot; Daryan, Ara; Kozliner, Lev; Mailyan, Bagrat; Hovsepyan, Gagik; Pokhsraryan, David; Sargsyan, David

2013-02-01

81

Situação da Mulher na Astronomia Brasileira  

NASA Astrophysics Data System (ADS)

O conteúdo desse texto surgiu de uma apresentação de mesmo título que fiz na XXXI Reunião Anual da Sociedade Astronômica Brasileira (SAB) em 2005. Esse tema foi inspirado originalmente pela minha participação no "2nd UIPAP International Conference on Women in Physics" realizado entre 23 e 25 de maio de 2005 no Rio de Janeiro. Essa é uma conferência internacional que acontece de três em três anos, sendo que a primeira ocorreu em 2002 na cidade de Paris, França. Participei dessa conferência como membro da delegação da Sociedade Brasileira de Física e um dos trabalhos que apresentei versava sobre a situação das mulheres na Astronomia brasileira, cujos resultados principais discorro a seguir. A situação das astrônomas, baseada nos dados dos sócios da SAB coletados no final de 2004, é comparada com a das físicas brasileiras e também com as nossas colegas americanas. Os dados identificam ainda uma maior evasão da carreira por parte das mulheres do que os homens. Alguns dos possíveis motivos da evasão são discutidos, como o desejo de constituir família e/ou isolamento. Resultados um tanto preocupantes com relação à distribuição de bolsas de produtividade do CNPq também são apresentados. As principais discussões e estratégias recomendadas nesse congresso são mencionadas de forma resumida ao final.

Silva, Adriana V. R.

2007-07-01

82

Progress of the NA62 RICH detector  

NASA Astrophysics Data System (ADS)

NA62 is the last generation Kaon experiment at CERN. Its main goal is to collect about 100 K+??+?bar nu events with 10% background. This implies to collect more than 1013 K+ decays with a backgound rejection factor better than 1012. The challenging aspect of the experiment is the suppression of Kaon decays with branching ratioes up to 10 orders of magnitude higher than the signal and similar experimental signature, such as K+??+?. To this purpose good PID (Particle IDentification) and kinematic rejection are required. Precise timing is also needed to correctly associate the ?+ with the parent K+ in an high rate environment. A RICH (Ring Imaging Cherenkov) detector is proposed as PID element, to identify ? contaminating the ? sample in the 15-35 GeV/c momentum range with inefficiency lower than 1% and to measure the arrival time with precision smaller than 100 ps. It will also be a key element for the NA62 trigger. A vacuum-proof cylindrical vessel with 4 m diameter, 17 m long, will be filled with Neon gas at atmospheric pressure. The Cherenkov light will be reflected by a mosaic of 20 hexagonal mirrors with 17 m focal length and collected by 2000 photomultipliers. The progress in the construction of the detector is described: the installation will start in January 2014, with completion foreseen in time for the first physics run of the NA62 experiment in the fall of 2014.

Lenti, Massimo

2014-01-01

83

NaNotechNologies alAcadmieuniversitaireLouvain  

E-print Network

NaNotechNologies 2011 alAcadémieuniversitaireLouvain #12;NaNotechNologies 2011 The AcadémieM, FUNDP, FUSL and UCL. In this particular case, this brochure « Nanotechnologies » has been pre- pared LOUVAIN - NaNotechNologies 3 Foreword Nanoscience and nanotechnology, often presented as the motors

Nesterov, Yurii

84

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.

85

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 conferência 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 contrapõem ao pensamento freudiano de O mal -estar na cultura. Diferenciam-se as posições

Paulo Albertini

2003-01-01

86

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

87

Cidadania negociada: descendentes de italianos na Repblica Velha Gacha  

E-print Network

Cidadania negociada: descendentes de italianos na República Velha Gaúcha Autora: Rejane Silva Penna familiar dos imigrantes italianos, aparecendo itens como nome, idade, localidade, religião, data de chegada descendentes de italianos na busca de uma participação mais efetiva na constituição do nascente Estado

Boyer, Edmond

88

The putative mechanism of Na+ absorption in euryhaline  

E-print Network

reserved. Keywords: Osmoregulation; Na+ /H+ exchanger; Na+ /K+ ATPase; Elasmobranch; Acid­base regulation 1 and acid or base secretion that are required for systemic acid­base regulation and osmoregulation in fresh). However, the definitive molecular identity of the transporter that mediates Na+ and acid transport across

Evans, David H.

89

33 CFR 147.833 - Na Kika FDS safety zone.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Na Kika FDS safety zone. 147.833 Section 147.833...ACTIVITIES SAFETY ZONES § 147.833 Na Kika FDS safety zone. (a) Description. Na Kika FDS, Mississippi Canyon 474 “A” (MC 474...

2010-07-01

90

Advanced Intermediate-Temperature Na-S Battery  

SciTech Connect

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

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

2013-01-01

91

FASE 7 Engenharia Automotiva Crditos Optativas: 6  

E-print Network

: 12 5401 5403 5404 5409 Fundamentos da Combustão Segunda-feira Terça-feira Quarta-feira Quinta Monitoramento e Controle de Tráfego Modelagem e Programação de Sistemas Grafos e Redes #12;Horário Disc. Sala

Floeter, Sergio Ricardo

92

Measurement and estimation for density of NaNO2-KNO3NaNO3 ternary molten salts  

Microsoft Academic Search

The densities of NaNO2-KNO3-NaNO3 ternary molten salts system were measured by Archimedean law. A method of density estimation was introduced. The result shows that the molar volume is additive in NaNO2-KNO3-NaNO3 ternary molten salts mixtures. According to that, an estimating equation for its density was obtained and it showed good agreement with the experimental data.

Fengguo Liu; Bingliang Gao; Shixing Wang; Zhaowen Wang; Zhongning Shi

2009-01-01

93

Interactions of NaCl and Na 2SO 4 on soil organic C mineralization after addition of maize straws  

Microsoft Academic Search

NaCl and Na2SO4 often dominate salt compositions in saline soils. While either salt alone affects soil organic matter mineralization, their interactions on soil organic matter dynamics are unknown. This study aimed to investigate interactive effects of the two salts on organic C mineralization and microbial biomass C of the saline soils after addition of maize straws. Both NaCl and Na2SO4

Xiao-gang Li; Feng-min Li; Qi-fu Ma; Zhi-jun Cui

2006-01-01

94

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

Vedovato, Natascia

2014-01-01

95

Crnica I Encontro Solar na UDC O pasado mrcores 24 de abril tivo lugar na Praza da Fraga (Campus da  

E-print Network

a exposición de aparellos solares instalada na Praza da Fraga, dende cociñas e fornos, ate cargadores para oCrónica I Encontro Solar na UDC O pasado mércores 24 de abril tivo lugar na Praza da Fraga (Campus da Zapateira) a primeira edición do Encontro Solar na UDC. Esta era a terceira das actividades

Fraguela, Basilio B.

96

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

97

Solvent electronic polarization effects on Na(+)-Na(+) and Cl(-)-Cl(-) pair associations in aqueous solution.  

PubMed

The formation of like-ion pairs, Na(+)-Na(+) and Cl(-)-Cl(-), in aqueous solution was studied by high-level ab initio methods, classical molecular dynamics (MD), QM/TIP5P, and QM/EFP MD (quantum mechanics/effective fragment potential molecular dynamics). Ab initio calculations on model clusters revealed that the Na(+)(H2O)nNa(+) (n = 2-4) clusters were significantly more stabilized by bridged waters than the corresponding Cl(-)(H2O)nCl(-) clusters. QM/EFP MD simulations in solution also predicted a clear local minimum near 3.6 Å only for the Na(+)-Na(+) pair, suggesting that Na(+)-Na(+) pairs may be more likely to form than Cl(-)-Cl(-) pairs in solution. Analysis of the hydration structures further showed that two-water bridged Na(+)-Na(+) pairs were dominant at the local minimum. The preferred formation of Na(+) like-ion pairs in solution appeared to come from significant short-range effects, in particular, charge delocalization (polarization) between the bridged oxygen p and the vacant valence Na(+) orbitals. PMID:23845041

Choi, Cheol Ho; Re, Suyong; Rashid, Mohammad H O; Li, Hui; Feig, Michael; Sugita, Yuji

2013-08-01

98

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

99

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

Microsoft Academic Search

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

L. O. Sillerud; J. W. Heyser

1984-01-01

100

Sodium-ion conduction in complex hydrides NaAlH4 and Na3AlH6  

NASA Astrophysics Data System (ADS)

We have studied sodium-ion conduction in complex hydrides NaAlH4 and Na3AlH6. The electrical conductivities of these complex hydrides were studied using ac impedance measurements at temperatures up to 363 K for NaAlH4 and 433 K for Na3AlH6. Nyquist plots obtained by the measurements indicated the sodium-ion conduction. Also, dc measurements showed that sodium-ion transference numbers of NaAlH4 and Na3AlH6 were almost unity. Na3AlH6 exhibited the sodium-ion conduction of 4.1 × 10-4 S/cm at 433 K. This study will open up research on complex hydrides as solid-state sodium-ion conductors.

Oguchi, H.; Matsuo, M.; Kuromoto, S.; Kuwano, H.; Orimo, S.

2012-02-01

101

[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

102

Acompanhamento nutricional individualizado de um paciente pediátrico: relato de caso Individualized nutritional care for a pediatric patient: case report Cuidado alimenticio individualizado para un paciente pediátrico: relato de caso  

Microsoft Academic Search

ReSumo: Este acompanhamento nutricional foi realizado com um paciente pediátrico com Insuficiência Renal Crônica, Síndrome Hemolítica Urêmica e Hipertensão Arterial, selecionado pela necessidade de se favorecer seu quadro clínico, devido às altas taxas de morbi-mortalidade em crianças renais. O objetivo deste trabalho é favorecer crescimento, desenvolvimento e sobrevida com qualidade. Esta pesquisa experimental, do tipo caso clínico, foi realizada com

Thaís Morgado Lamonica; Vera Sílvia Frangella; Elen Pessina

103

Minimizing Load Effects on NA4 Gear Vibration Diagnostic Parameter  

NASA Technical Reports Server (NTRS)

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

Dempsey, Paula J.; Zakrajsek, James J.

2001-01-01

104

Influence of intramembrane electric charge on Na,K-ATPase.  

PubMed

Effects of lipophilic ions, tetraphenylphosphonium (TPP+) and tetraphenylboron (TPB-), on interactions of Na+ and K+ with Na,K-ATPase were studied with membrane-bound enzyme from bovine brain, pig kidney, and shark rectal gland. Na+ and K+ interactions with the inward-facing binding sites, monitored by eosin fluorescence and phosphorylation, were not influenced by lipophilic ions. Phosphoenzyme interactions with extracellular cations were evaluated through K(+)-, ADP-, and Na(+)-dependent dephosphorylation. TPP+ decreased: 1) the rate of transition of ADP-insensitive to ADP-sensitive phosphoenzyme, 2) the K+ affinity and the rate coefficient for dephosphorylation of the K-sensitive phosphoenzyme, 3) the Na+ affinity and the rate coefficient for Na(+)-dependent dephosphorylation. Pre-steady state phosphorylation experiments indicate that the subsequent occlusion of extracellular cations was prevented by TPP+. TPB- had opposite effects. Effects of lipophilic ions on the transition between phosphoenzymes were significantly diminished when Na+ was replaced by N-methyl-D-glucamine or Tris+, but were unaffected by the replacement of Cl- by other anions. Lipophilic ions affected Na-ATPase, Na,K-ATPase, and p-nitrophenylphosphatase activities in accordance with their effects on the partial reactions. Effects of lipophilic ions appear to be due to their charge indicating that Na+ and K+ access to their extracellular binding sites is modified by the intramembrane electric field. PMID:7876184

Klodos, I; Fedosova, N U; Plesner, L

1995-03-01

105

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

106

Hypoxic responses of Na+/K+ ATPase in trout hepatocytes.  

PubMed

Reduction in oxygenation induces inhibition of Na+/K+ ATPase in a number of cells and tissues, including hepatocytes. When not reversed, decrease in Na+/K+ pump activity leads to a gradual Na+ accumulation, cell swelling and death. However, when accompanied by suppression of dissipative cation pathways, it has also been shown to be a beneficial adaptive strategy used by some hypoxia-tolerant species to reduce ATP consumption during prolonged periods of anoxia. This study aims to investigate acute hypoxic responses of the Na+/K+ ATPase in primary cultures of trout hepatocytes. Gradual decrease in oxygenation was followed by an instantaneous transient dose-dependent downregulation of the Na+/K+ ATPase transport activity, but was without an effect on hydrolytic function of the enzyme. Hypoxia-induced inhibition of active K+ influx was reversed spontaneously when hypoxic incubation time exceeded 20 min. The stimulating effect of prolonged hypoxic exposure on the Na+/K+ pump is most probably secondary to hypoxia-induced activation of the Na+/H+ exchanger with the following Na+ accumulation leading to Na+/K+ ATPase activation. Hypoxia-induced inhibition of the Na+/K+ pump was not caused by ATP depletion or global oxidative stress. However, local controlled production of reactive oxygen species seems to play an important role in hypoxia-induced regulation of the Na+/K+ ATPase. Treatment of cells with mercaptopropionyl glycine (MPG), a scavenger of OH*-, abolished hypoxia-induced inhibition of the Na+/K+ ATPase. Earlier on we have shown that activation of Na+/H+ exchanger under hypoxic conditions can be opposed by MPG treatment as well. Taken together our results suggest that regulation of both oxygen-sensitive transporters may be accomplished by local changes in free radical production. PMID:15879061

Bogdanova, A; Grenacher, B; Nikinmaa, M; Gassmann, M

2005-05-01

107

Theoretical calculation of low-lying states of NaAr and NaXe  

NASA Technical Reports Server (NTRS)

Potential curves as well as dipole moments and linking transition moments are calculated for the ground X 2 Sigma + and low lying excited A 2 Pi, B 2 Sigma +, C 2 Sigma +, (4) 2 Sigma +, (2) 2 Pi and (1) 2 Delta states of NaAr and NaXe. Calculations are performed using a self-consistent field plus configuration-interaction procedure with the core electrons replaced by an ab initio effective core potential. The potential curves obtained are found to be considerably less repulsive than the semiempirical curves of Pascale and Vandeplanque (1974) and to agree well with existing experimental data, although the binding energies of those states having potential minima due to van der Waals interactions are underestimated. Emission bands are also calculated for the X 2 Sigma + - C 2 Sigma + excimer transitions of NaAr and NaXe using the calculated transition moments and potential curves, and shown to agree well with experiment on the short-wavelength side of the maximum.

Laskowski, B. C.; Langhoff, S. R.; Stallcop, J. R.

1981-01-01

108

Precise Control of Na Content in the Layered Cobaltate ?-Na x CoO2  

NASA Astrophysics Data System (ADS)

We have developed a preparation method for precisely controlling the Na content x of a ?-Na0.7CoO2 precursor by a halogen oxidation technique in the range 0.50 ? x ? 0.70. The Na content of the precursor was reduced in a concentration-controlled I2-CH3CN solution. The magnetic susceptibility of ?-Na x CoO2 shows Curie-Weiss (CW)-type paramagnetism ( x ? 0.70) or Pauli-type paramagnetism ( x ? 0.50). The boundary of the CW and Pauli paramagnetic phases was identified at x ? 0.61. The content and temperature for a disorder-order transition from the ? phase to a sqrt{7}a_0 × sqrt{7}a_0 superstructure were accurately elucidated by differential scanning calorimetry (DSC) measurement. A phase transition for the 0.52 ? x ? 0.54 sample was observed at 250 K by DSC measurements. The heat absorption of the 0.52 ? x ? 0.54 samples was of the same order of magnitude as that of the transition from the ? phase to the sqrt{7}a_0 × sqrt{7}a_0 phase.

Igarashi, Dai; Miyazaki, Yuzuru; Yubuta, Kunio; Kajitani, Tsuyoshi

2010-09-01

109

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

110

Interaction of NaCl/g/ and HCl/g/ with condensed Na2SO4. [in hot corrosion processes  

NASA Technical Reports Server (NTRS)

Na2SO4(l)-NaCl(g) interactions were studied at a total pressure of one atmosphere of air or oxygen for various temperatures of Na2SO4(l) and for various partial pressures of NaCl(g) and H2O(g). Mass spectrometric sampling techniques were used to identify and monitor gas phase species. Continuous recording thermomicrogravimetric measurements were conducted to determine condensed phase weight change rates. Experimental measurements were supplemented with thermodynamic calculations. Numerous experiments were performed at sample temperatures of 900 and 1000 C with 300 ppm NaCl(g). In these experiments, the reproducibility of the Na2SO4 vaporization weight loss rate and initial weight gain upon addition of NaCl(g) were found to be satisfactory. It was found that the addition of NaCl(g) to air flowing over Na2SO4(l) at 900 and 1000 C enhances the rate of weight loss of the Na2SO4(l). This enhancement increases when H2O(g) is also added to the air flow.

Stearns, C. A.; Kohl, F. J.; Fryburg, G. C.; Miller, R. A.

1977-01-01

111

Theoretical calculations on the NaS and NaS+ radicals: electronic structure, spectroscopy and spin-orbit couplings  

NASA Astrophysics Data System (ADS)

We used an ab initio methodology for the computation of the potential energy curves of the lowest electronic states of NaS and NaS+ diatomics. Using these highly correlated wavefunctions, we calculated their spin-orbit couplings. The X2? and the A2?+ electronic states of NaS are found to possess deep potential wells. The upper bound electronic states have either shallow potential wells located in the molecular region or potentials of ~1 eV depth located for large NaS distances. For NaS+, our calculations reveal the existence of shallow potentials for all states correlating to the four lowest dissociation limits. Using our potentials, we calculated an accurate set of spectroscopic constants for NaS and NaS+. Most of the data relative to the electronic excited states represent predictions. The spin-orbit induced predissociation of NaS(A2?+ is discussed. Finally, our cationic potentials and the NaS(X2?) potential were used for the prediction of the single ionization spectrum of NaS. Tables S1-S7 are only available in electronic form at www.epj.org

Khadri, F.; Hochlaf, M.

2012-05-01

112

The Putative Plasma Membrane Na+/H+ Antiporter SOS1 Controls Long-Distance Na+ Transport in Plants  

PubMed Central

The salt tolerance locus SOS1 from Arabidopsis has been shown to encode a putative plasma membrane Na+/H+ antiporter. In this study, we examined the tissue-specific pattern of gene expression as well as the Na+ transport activity and subcellular localization of SOS1. When expressed in a yeast mutant deficient in endogenous Na+ transporters, SOS1 was able to reduce Na+ accumulation and improve salt tolerance of the mutant cells. Confocal imaging of a SOS1–green fluorescent protein fusion protein in transgenic Arabidopsis plants indicated that SOS1 is localized in the plasma membrane. Analysis of SOS1 promoter–?-glucuronidase transgenic Arabidopsis plants revealed preferential expression of SOS1 in epidermal cells at the root tip and in parenchyma cells at the xylem/symplast boundary of roots, stems, and leaves. Under mild salt stress (25 mM NaCl), sos1 mutant shoot accumulated less Na+ than did the wild-type shoot. However, under severe salt stress (100 mM NaCl), sos1 mutant plants accumulated more Na+ than did the wild type. There also was greater Na+ content in the xylem sap of sos1 mutant plants exposed to 100 mM NaCl. These results suggest that SOS1 is critical for controlling long-distance Na+ transport from root to shoot. We present a model in which SOS1 functions in retrieving Na+ from the xylem stream under severe salt stress, whereas under mild salt stress it may function in loading Na+ into the xylem. PMID:11884687

Shi, Huazhong; Quintero, Francisco J.; Pardo, Jose M.; Zhu, Jian-Kang

2002-01-01

113

Pyrophosphate-Fueled Na+ and H+ Transport in Prokaryotes  

PubMed Central

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

Malinen, Anssi M.; Luoto, Heidi H.

2013-01-01

114

ATUAÇÃO DO FISIOTERAPEUT A NO ATENDIMENTO DOMICILIAR DE PACIENTES NEUROLÓGICOS: A EFETIVIDADE SOB A VISÃO DO CUIDADOR The physiotherapist's performance in the domicile attendance of neurological patients: the effectiveness under the caretaker's point of view  

Microsoft Academic Search

RESUMO Alguns pacientes neurológicos apresentam alterações e distúrbios da cinesia funcional que os impedem de exercer sua autonomia física, repercutindo sobre sua estrutura psicológica e socioeconômica. Em decorrência desses distúrbios, os pacientes possuem graus variáveis de incapacidade que determinam níveis de dependência ao cuidador. Este trabalho teve como objetivo investigar a efetividade da Fisioterapia no quadro clínico do paciente neurológico,

Diolina Nogueira Leite Felício; Ana Luiza; Veras Franco; Maria Edvani Araújo Torquato; Ana Paula de Vasconcellos

115

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

116

Scheelite-type NaDy(WO4)2  

PubMed Central

The title compound sodium dysprosium(III) bis­[tungs­tate(VI)], NaDy(WO4)2, has been synthesized under high temperature solution growth (HTSG) conditions in air. The compound crystallizes with the scheelite structure and is composed of isolated WO4 tetra­hedra ( symmetry) with one set of bond lengths and distorted [(Na/Dy)O8] dodeca­hedra ( symmetry; occupancy ratio Na:Dy = 1:1) with two sets of bond lengths. PMID:21579906

Zhao, Dan; Li, Feifei; Cheng, Wendan; Zhang, Hao

2010-01-01

117

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

118

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

119

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

PubMed

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

Sillerud, L O; Heyser, J W

1984-05-01

120

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

SciTech Connect

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

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

1984-05-01

121

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, Jürgen

2014-08-01

122

Angular distributions of photoelectrons from free Na clusters  

SciTech Connect

We explore, from a theoretical perspective, photoelectron angular distributions (PADs) of the Na clusters Na{sub 8}, Na{sub 10}, Na{sub 12}, Na{sub 18}, Na{sub 3}{sup +}, Na{sub 11}{sup +}, Na{sub 13}{sup +}, and Na{sub 19}{sup +}. The basis of the description is the time-dependent local-density approximation (TDLDA), augmented by a self-interaction correction (SIC) to describe ionization properties correctly. The scheme is solved on a numerical grid in coordinate space with absorbing bounds. We assume for each cluster system an isotropic ensemble of free clusters and develop for the case of one-photon emission analytical formulas for computing the orientation-averaged PAD on the basis of a few TDLDA-SIC calculations for properly chosen reference orientations. It turns out that all the information in the averaged PAD is contained in one anisotropy parameter. We find that this parameter varies very little with system size, but as a whole is crucially influenced by the detailed ionic structure. We also make comparisons with direct orientation averaging and consider one example reaching outside the perturbative regime.

Wopperer, P.; Dinh, P. M. [Universite de Toulouse, UPS, Laboratoire de Physique Theorique, IRSAMC, F-31062 Toulouse Cedex, France and CNRS, UMR 5152, F-31062 Toulouse Cedex (France); Faber, B.; Reinhard, P.-G. [Institut fuer Theoretische Physik, Universitaet Erlangen, D-91058 Erlangen (Germany); Suraud, E. [Universite de Toulouse, UPS, Laboratoire de Physique Theorique, IRSAMC, F-31062 Toulouse Cedex, France and CNRS, UMR 5152, F-31062 Toulouse Cedex (France); Institut fuer Theoretische Physik, Universitaet Erlangen, D-91058 Erlangen (Germany)

2010-12-15

123

Kaolin-based geopolymers with various NaOH concentrations  

NASA Astrophysics Data System (ADS)

Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6-14 mol/L and was mixed with the sodium silicate solution at a Na2SiO3/NaOH mass ratio of 0.24 to prepare an activator solution. The kaolin-to-activator solution mass ratio used was 0.80. This paper aimed to analyze the effect of NaOH concentration on the compressive strength of kaolin geopolymers at 80°C for 1, 2, and 3 d. Kaolin geopolymers were stable in water, and strength results showed that the kaolin binder had adequate compressive strength with 12 mol/L of NaOH concentration. When the NaOH concentration increased, the SiO2/Na2O decreased. The increased Na2O content enhanced the dissolution of kaolin as shown in X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. However, excess in this content was not beneficial for the strength development of kaolin geopolymers. In addition, there was the formation of more geopolymeric gel in 12 mol/L samples. The XRD pattern of the samples showed a higher amorphous content and a more geopolymer bonding existed as proved by FTIR analysis.

Heah, C. Y.; Kamarudin, H.; Mustafa Al Bakri, A. M.; Bnhussain, M.; Luqman, M.; Khairul Nizar, I.; Ruzaidi, C. M.; Liew, Y. M.

2013-03-01

124

Alterações cognitivas e demência na doença de Parkinson.  

E-print Network

??Na Doença de Parkinson (DP), mesmo nos seus estádios iniciais, vários domínios cognitivos estão alterados, incluindo funções executivas, funções visuo-espaciais, memória e linguagem. O risco… (more)

Santos, Filipe Sobral Blanco Heleno

2009-01-01

125

Na,K-ATPase: radiation inactivation studies.  

PubMed

Na,K-ATPase from duck salt gland and ox brain in the membrane-bound or solubilized form was studied by the radiation inactivation technique using ATP, CTP, GTP or p-NPP as substrates. The values of radiation inactivation size (RIS) were compared with the target size (TS) for the alpha-subunit of the enzyme obtained by an independent method as well as with analytical centrifugation data obtained for C12E8-solubilized enzyme. It was concluded that during ATP (CTP) hydrolysis the enzyme operates as an oligomeric structure; the complex formation requires the presence of K+ and adenosine triphosphate binding to the sites with a low affinity for the nucleotide. Specially designed experiments revealed that the degree of enzyme oligomerization increases with an increase in the microviscosity of the membrane lipid environment. PMID:2167088

Boldyrev, A A; Lopina, O D; Fedosova, N U

1990-01-01

126

Questões mais freqüentes na área de astronomia  

NASA Astrophysics Data System (ADS)

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

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

2003-08-01

127

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

128

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

129

Extracellular Hypotonicity Increases Na,K-ATPase Cell Surface Expression via Enhanced Na Influx in Cultured Renal Collecting Duct Cells  

Microsoft Academic Search

In the renal collecting duct (CD), the Na,K-ATPase, which provides the driving force for Na absorption, is under tight multifactorial control. Because CD cells are physiologi- cally exposed to variations of interstitial and tubular fluid osmolarities, the effects of extracellular anisotonicity on Na,K- ATPase cell surface expression were studied. Results show that hypotonic conditions increased, whereas hypertonic conditions had no

MANLIO VINCIGUERRA; SERGE ARNAUDEAU; DAVID MORDASINI; MARTINE ROUSSELOT; MARCELLE BENS; ALAIN VANDEWALLE; PIERRE-YVES MARTIN; UDO HASLER; ERIC FERAILLE

2004-01-01

130

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

NASA Astrophysics Data System (ADS)

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

Nafisi, Shohreh; Manouchehri, Firouzeh; Montazeri, Maryam

2011-12-01

131

O'3-Na(x)VO2 system: a superstructure for Na(1/2)VO2.  

PubMed

The electrochemical cycling in a sodium battery of the lamellar oxide NaVO(2) is reversible in the Na(x)VO(2) composition range 1/2 ? x ? 1. The complex electrochemical curve reveals the presence of several transitions taking place during deintercalation. With the help of in situ X-ray diffraction, we observed the structural transitions taking place between Na(2/3)VO(2) and Na(1/2)VO(2). The diffractograms show the presence of several monophasic domains separated by biphasic domains. All phases present a monoclinic distortion of the ?-NaFeO(2) structure in the composition range 1/2 ? x ? 2/3. Moreover the presence of a superstructure is evidenced for Na(1/2)VO(2). It is the first time that an ordered structure is reported at the Na(1/2)MO(2) composition with an O'3 oxygen stacking. A thorough investigation of electrochemically obtained O'3-Na(1/2)VO(2) was performed. The structure refinement reveals the existence of a sodium/vacancy ordering, with a peculiar arrangement of the V-V distances hinting at a pairing of vanadium atoms. Our first measurements of the physical properties of O'3-Na(1/2)VO(2) show a semiconductor behavior and a complex thermal dependence of the magnetic susceptibility related to the pairing of the vanadium atoms. PMID:23009092

Didier, Christophe; Guignard, Marie; Darriet, Jacques; Delmas, Claude

2012-10-15

132

Expression of diverse Na+ channel messenger RNAs in rat myocardium. Evidence for a cardiac-specific Na+ channel.  

PubMed Central

This study examined the diversity of Na+ channel gene expression in intact cardiac tissue and purified myocardial cells. The screening of neonatal rat myocardial cell cDNA libraries with a conserved rat brain Na+ channel cDNA probe, resulted in the isolation and characterization of a putative rat cardiac Na+ channel cDNA probe (pCSC-1). The deduced amino acid sequence of pCSC-1 displayed a striking degree of homology with the eel, rat brain-1, and rat brain-2 Na+ channel, thereby identifying pCSC-1 as a related member of the family of Na+ channel genes. Northern blot analysis revealed the expression of a 7-kb CSC-1 transcript in rat cardiac tissue and purified myocardial cells, but little or no detectable expression of CSC-1 in rat brain, skeletal muscle, denervated skeletal muscle, or liver. Using RNase protection and Northern blot hybridization with specific rat brain Na+ channel gene probes, expression of the rat brain-1 Na+ channel was observed in rat myocardium, but no detectable expression of the rat brain-2 gene was found. This study provides evidence for the expression of diverse Na+ channel mRNAs in rat myocardium and presents the initial characterization of a new, related member of the family of Na+ channel genes, which appears to be expressed in a cardiac-specific manner. Images PMID:2544627

Sills, M N; Xu, Y C; Baracchini, E; Goodman, R H; Cooperman, S S; Mandel, G; Chien, K R

1989-01-01

133

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

134

Central role of the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) in sodium bioenergetics of Vibrio cholerae.  

PubMed

Abstract Vibrio cholerae is a Gram-negative bacterium that lives in brackish or sea water environments. Strains of V. cholerae carrying the pathogenicity islands infect the human gut and cause the fatal disease cholera. Vibrio cholerae maintains a Na+ gradient at its cytoplasmic membrane that drives substrate uptake, motility, and efflux of antibiotics. Here, we summarize the major Na+-dependent transport processes and describe the central role of the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR), a primary Na+ pump, in maintaining a Na+-motive force. The Na+-NQR is a membrane protein complex with a mass of about 220 kDa that couples the exergonic oxidation of NADH to the transport of Na+ across the cytoplasmic membrane. We describe the molecular architecture of this respiratory complex and summarize the findings how electron transport might be coupled to Na+-translocation. Moreover, recent advances in the determination of the three-dimensional structure of this complex are reported. PMID:25205724

Steuber, Julia; Halang, Petra; Vorburger, Thomas; Steffen, Wojtek; Vohl, Georg; Fritz, Günter

2014-12-01

135

Measurement of intravascular Na(+) during increased CBF using (23)Na NMR with a shift reagent.  

PubMed

Sodium ions are intimately involved with neural activity. Thus, it is highly desirable to devise a way of mapping brain activity via sodium imaging. Sodium ions exist in the extravascular and intravascular spaces. To separate the two components, the shift reagent Tm(DOTP)(5-) was intravenously introduced into rats. Intravascular sodium changes in the rat brain were measured during increased blood flow induced by hypercapnia using volume-localized (23)Na-NMR. The intravascular sodium changes, equivalent to cerebral blood volume changes, are significant during hypercapnia conditions and correlate well with the increase in arterial pCO(2). This suggests that the intravascular sodium change is dominant in total (23)Na spectroscopy or imaging of the brain during blood flow increase induced by external perturbation. PMID:11746937

Ronen, I; Kim, S G

2001-01-01

136

Crystallization of single phase (K, Na)clinoptilolite  

Microsoft Academic Search

A single phase (K, Na)-clinoptilolite was hydrothermally crystallized without seed crystals from a reactant mixture of (K, Na)-aluminosilicate gel slurry through homogeneous mixing at 150 °C for 144 h. Compositions of the reactant mixtures and reaction temperatures to obtain the clinoptilolite were restricted within narrow limits in the case of syntheses without seed crystals, while the compositions and temperatures were

Shigeo Satokawa; Keiji Itabashi

1997-01-01

137

Moderate temperature rechargeable NaNiS2 cells  

NASA Technical Reports Server (NTRS)

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

Abraham, K. M.

1983-01-01

138

Študent naj bo na ameriškem kolidžu  

E-print Network

Ja s fotografij in pripovedovanj prijateljev, ki so biH kot fulbrightovci na Kansa~ki univerzi, vsaj deset let pred svojim prihodom v te kraje, kjer je mož, Kalifornijec, dobil mesto na slavistiki. Nekaj let kasneje sem se tudi sama tu zaposl.i1a kot lektorica...

Pirnat-Greenberg, Marta

2007-01-01

139

Extending 3-Frequency Na Doppler Lidar Wind and Temperature Measurements into Lower Atmosphere with Na Double-Edge Magneto-Optic Filters (Na-DEMOF)  

NASA Astrophysics Data System (ADS)

An important atmospheric process is the wave coupling among different layers. It is crucial to trace waves from their source regions in the lower atmosphere to their dissipation regions in the middle and upper atmosphere. This requires the profiling of wind and temperature simultaneously from the lower to the upper atmosphere. Utilizing Doppler shift and Doppler broadening effects, various types of Doppler lidars can measure wind and temperature in different atmospheric regions. However, none of the single lidars is able to profile both variables throughout the atmosphere. Resonance fluorescence Na Doppler lidars measure wind and temperature simultaneously in the mesosphere and lower thermosphere. They have made significant contributions to the study of wave dynamics. Unfortunately, their measurements are limited to 80-105 km where the trace gas Na atoms are available. We proposed to incorporate a Na double-edge magneto-optic filter (Na-DEMOF) into the receiver of a 3-frequency Na Doppler lidar to extend its wind and temperature measurements into the lower atmosphere. Two prototypes based on cold- and hot-cell designs were constructed and characterized with laboratory tests. The hot-cell filter showed superior performances than the cold-cell containing buffer gas. The hot-cell Na-DEMOF was also successfully modeled by quantum mechanics calculations. Lidar simulations were conducted for analysis of measurement errors in the altitude range of 15-50 km with the hot-cell filter developed. Field test using the hot-cell Na-DEMOF with the Colorado State University Na lidar is under its way and the initial results will be reported and compared to lidar simulation.

Huang, W.; Chu, X.; Wiig, J.; Williams, B. P.; Harrell, S.; She, C.

2008-12-01

140

Comparative studies of etching mechanisms of CR-39 in NaOH/H 2O and NaOH/ethanol  

NASA Astrophysics Data System (ADS)

The bulk etch rate for CR-39 in NaOH/ethanol was faster than those in aqueous solution of NaOH (NaOH/H 2O). Furthermore, a layer of precipitate always accumulates on the surface of CR-39 detector during etching in NaOH/ethanol, which is absent during etching in NaOH/H 2O. In the present work, mass spectrometry results have shown that the same etched products are present in the etchants of NaOH/H 2O and NaOH/ethanol after etching of CR-39. This shows that CR-39 has the same etching mechanism in both etchants. These etched products support the etching mechanism of scission of the carbonate ester bond in CR-39 by the hydroxide ion through basic hydrolysis of ester. The difference in the bulk etch rates can be explained in terms of the solubility of the etched products in the etchants. FTIR analyses of the solute formed from the etchants show the formation of allyl alcohol and carbonate during etching in both etchants. The FTIR spectra of the precipitate formed at the surface of CR-39 detectors during etching in NaOH/ethanol has also shown that sodium carbonate is present in the precipitate. Finally, XRD analyses of the solute formed from the etchants show the formation of sodium bicarbonate and sodium carbonate in the etchant of NaOH/H 2O after etching and the formation of the mineral natrite and thermonatrite in the etchant of NaOH/ethanol as well as in the layer of precipitate on the surface of the CR-39 detector formed during etching in NaOH/ethanol.

Tse, K. C. C.; Nikezic, D.; Yu, K. N.

2007-10-01

141

Study of acoustic activity of NaBrO3  

NASA Astrophysics Data System (ADS)

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

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

1987-05-01

142

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); Zi-jian Xie (University of Toledo Health Science Campus)

2008-08-01

143

Regulation of intracellular and mitochondrial Na in health and disease  

PubMed Central

The transmembrane sodium gradient is essential for both excitability of the cardiac cell and the regulation of the cytoplasmic concentrations of Ca and protons. In addition, movements of Na across the mitochondrial membrane affect matrix protons and calcium. In the first part of the review we discuss the most important pathways responsible for sarcolemmal and mitochondrial sodium movements. The bulk of the review considers the changes of intracellular Na concentration ([Na+]i) that occur in disease; specifically ischemia, reperfusion and heart failure. We review evidence implicating the increase of intracellular sodium to either increased influx of sodium (via either sodium channels or sodium-hydrogen exchange) or, alternatively, to decreased efflux on the Na-K pump. While much has been learnt about sodium regulation in the heart, there are still many unanswered questions, particularly concerning mitochondrial Na regulation. PMID:19213964

Murphy, Elizabeth; Eisner, David A.

2009-01-01

144

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

145

LiNa(5)Mo(9)O(30).  

PubMed

The tite compound, lithium penta-sodium nona-molybdate, LiNa(5)Mo(9)O(30), was synthesized by solid-state reaction. The three-dimensional [Mo(9)O(30)](6-) framework is built up from MoO(6) octa-hedra and MoO(5) bipyramids, linked together by edges and corners. The framework delimits two types of inter-secting 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 K(2)Mo(3)O(10), K(2)Mo(4)O(13), Cs(2)Mo(7)O(22), Na(6)Mo(10)O(33) and Na(6)Mo(11)O(36) compounds are discussed. PMID:23284311

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

2012-11-01

146

Electrogenic Na+/HCO3- cotransport in neuroglia.  

PubMed

Membrane potential recording from glial cells in Necturus optic nerve in the presence of 2 mM Ba++, which was added to block the K+ conductance, gave the following results. 1) In HCO3- -free, low-Na+ solutions (11% of control; Na+ replaced with N-methyl-D-glucamine), the hyperpolarizing effect of adding 10 mM HCO3- was reduced by approximately 80%. 2) 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid (SITS, 0.1 or 1 mM) reduced the effect of HCO3- by at least 50%. 3) In the presence of HCO3-, reduction of Na+ caused a depolarization which was much larger than that observed in nominally HCO3- -free solutions. These observations indicate the presence in the glial membrane of an electrogenic Na+/HCO3- cotransporter in which the stoichiometry of HCO3- to Na+ is greater than 1. PMID:2852638

Astion, M L; Orkand, R K

1988-01-01

147

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

148

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

149

Temperature dependent study of viscosity of KNO3–NaNO2–NaNO3 ternary molten salts  

Microsoft Academic Search

Temperature dependent study of viscosity has been employed for KNO3–NaNO2–NaNO3 ternary molten salts using various empirical and statistical theories. The values derived are found to be in a fairly good agreement with the experimental values reported in the literature. Thus, the theories can be validated for its application to the multicomponent systems in general.

R. K. Shukla; Sonu Dwivedi; Piyush Awasthi

2006-01-01

150

Nuclear Magnetic Resonance Diffusion Studies of 23Na in Beta Alumina, Effect of Water on the 23Na Quadrupole Interaction  

Microsoft Academic Search

Measurements of the 23Na nuclear magnetic resonance spectra in samples of sodium beta alumina are interpreted in terms of sodium diffusion and water absorption. Intense motional narrowing is observed below room temperature consistent with the low activation energy for diffusion. The 23Na spectra from finely powdered material show effects, similar to those observed in zeolites, due to absorbed water. The

D. Kline; H. S. Story; W. L. Roth

1972-01-01

151

Structural transformation from NaHTi 3O 7 nanotube to Na 2Ti 6O 13 nanorod  

NASA Astrophysics Data System (ADS)

NaHTi 3O 7 nanotubes were synthesized by the hydrothermal method. Temperature effects of the nanotubes are examined by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), thermal gravity analysis (TGA), and Raman spectroscopy. With increasing the annealing temperature NaHTi 3O 7 nanotubes undergo a slight degradation and more degradation of the tubular shape, respectively at 300 and 500 ?C, and finally become complete Na 2Ti 6O 13 nanorods after annealing at 700 ?C for 1 hour. The structure characters and lattice dynamics of both nanotubes and nanorods were investigated. The transformation mechanism between NaHTi 3O 7 nanotubes and Na 2Ti 6O 13 nanorods is discussed to be attributed to release of the structural water in the interlayer space during self-oriented attachments, and to take more stable configuration with low energy.

Zhu, K. R.; Yuan, Y.; Zhang, M. S.; Hong, J. M.; Deng, Y.; Yin, Z.

2007-12-01

152

Production of Secondary Radioactive 21Na Beam for the Study of 21Na(?,p)24Mg Stellar Reaction  

NASA Astrophysics Data System (ADS)

The availability of radioactive beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar explosions such as novae, X-ray burst and supernovae. By using an in-flight low-energy radioisotope beam separator (CRIB) at Center for Nuclear Study (CNS), University of Tokyo, we have successfully produced the 21Na proton-rich beam for the study of 21Na(?,p)24Mg reaction which is related to the astrophysically important production of 22Na in the stellar explosive environments. Since it is the first time when this reaction is studied experimentally, we have performed a test experiment to produce the 21Na beam and to estimate the feasibility of the experimental study of 21Na(?,p)24Mg reaction.

Binh, Dam Nguyen; Khiem, Le Hong; Kubono, S.; Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Kim, A.

2008-04-01

153

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

154

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; Juárez, Oscar; Barquera, Blanca

2015-01-20

155

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

156

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

SciTech Connect

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

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

1986-08-01

157

Hydrogen Bond Dynamics in Aqueous NaBr Solutions  

SciTech Connect

Hydrogen bond dynamics of water in NaBr solutions are studied by using ultrafast 2D IR vibrational echo spectroscopy and polarization-selective IR pump-probe experiments. The hydrogen bond structural dynamics are observed by measuring spectral diffusion of the OD stretching mode of dilute HOD in H{sub 2}O in a series of high concentration aqueous NaBr solutions with 2D IR vibrational echo spectroscopy. The time evolution of the 2D IR spectra yields frequency-frequency correlation functions, which permit quantitative comparisons of the influence of NaBr concentration on the hydrogen bond dynamics. The results show that the global rearrangement of the hydrogen bond structure, which is represented by the slowest component of the spectral diffusion, slows, and its time constant increases from 1.7 to 4.8 ps as the NaBr concentration increases from pure water to {approx}6 M NaBr. Orientational relaxation is analyzed with a wobbling-in-a-cone model describing restricted orientational diffusion that is followed by complete orientational randomization described as jump reorientation. The slowest component of the orientational relaxation increases from 2.6 ps (pure water) to 6.7 ps ({approx}6 M NaBr). Vibrational population relaxation of the OD stretch also slows significantly as the NaBr concentration increases.

Park, S.; Fayer, M.D.; /Stanford U., Chem. Dept. /SLAC, SSRL

2009-04-29

158

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

159

Phyla- and Subtype-Selectivity of CgNa, a Na+ Channel Toxin from the Venom of the Giant Caribbean Sea Anemone Condylactis Gigantea  

PubMed Central

Because of their prominent role in electro-excitability, voltage-gated sodium (NaV) channels have become the foremost important target of animal toxins. These toxins have developed the ability to discriminate between closely related NaV subtypes, making them powerful tools to study NaV channel function and structure. CgNa is a 47-amino acid residue type I toxin isolated from the venom of the Giant Caribbean Sea Anemone Condylactis gigantea. Previous studies showed that this toxin slows the fast inactivation of tetrodotoxin-sensitive NaV currents in rat dorsal root ganglion neurons. To illuminate the underlying NaV subtype-selectivity pattern, we have assayed the effects of CgNa on a broad range of mammalian isoforms (NaV1.2–NaV1.8) expressed in Xenopus oocytes. This study demonstrates that CgNa selectively slows the fast inactivation of rNaV1.3/?1, mNaV1.6/?1 and, to a lesser extent, hNaV1.5/?1, while the other mammalian isoforms remain unaffected. Importantly, CgNa was also examined on the insect sodium channel DmNaV1/tipE, revealing a clear phyla-selectivity in the efficacious actions of the toxin. CgNa strongly inhibits the inactivation of the insect NaV channel, resulting in a dramatic increase in peak current amplitude and complete removal of fast and steady-state inactivation. Together with the previously determined solution structure, the subtype-selective effects revealed in this study make of CgNa an interesting pharmacological probe to investigate the functional role of specific NaV channel subtypes. Moreover, further structural studies could provide important information on the molecular mechanism of NaV channel inactivation. PMID:21833172

Billen, Bert; Debaveye, Sarah; Béress, Lászlo; Tytgat, Jan

2010-01-01

160

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

PubMed

The growth of the aggregates of the dihydroxylated bile salt sodium taurodeoxycholate (NaTDC) upon NaCl addition and the involvement of the counterion were investigated by NMR spectroscopy of monoatomic ionic species. (23)Na T(1) values from 0.015, 0.100, and 0.200 mol kg(-1) NaTDC solutions in D(2)O, at variable NaCl content, proved to be sensitive to the transition from primary to secondary aggregates, which occurs in the former sample, and to intermicellar interaction. Some (79)Br NMR measurements were performed on a 0.100 mol kg(-1) NaTDC sample added by NaBr in place of NaCl for comparison purposes. The (23)Na, (35)Cl, and (37)Cl double quantum filtered (DQF) patterns, from the 0.100 mol kg(-1) NaTDC sample, and (23)Na ones also from the 0.200 mol kg(-1) NaTDC one, in the presence of 0.750 mol kg(-1) NaCl, are a clear manifestation of motional anisotropy. Moreover, the DQF spectra of (23)Na and (37)Cl, which possess close quadrupole moments, display a striking similarity. The DQF lineshapes were simulated exploiting the Scilab environment to obtain an estimate of the residual quadrupole splitting magnitude. These results support the description of NaTDC micelles as cylindrical aggregates, strongly interacting at high ionic strengths, and capable of association with added electrolytes. PMID:23127873

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

2013-02-15

161

Acrscimo de no acesso ao  

E-print Network

Acréscimo de 6600 vagas no acesso ao superior Ensino Samuel Silva Segunda fase de acesso ao ensino público, que tem um acréscimo de mais de 6600 lu- gares face ao que havia sobrado na primeira fase mais de 6600 vagas tinham sido preenchidas na primeira fase, mas os alunos colocados não chegaram

Instituto de Sistemas e Robotica

162

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

NASA Astrophysics Data System (ADS)

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

Smirnov, A. D.

2014-09-01

163

VIEW OF CEMETERY SECTIONS NA (NEW ADDITION) AND NAWS (NEW ...  

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

VIEW OF CEMETERY SECTIONS NA (NEW ADDITION) AND NAWS (NEW ADDITION WEST SIDE) ALONG NORTH DRIVE, WITH MAINTENANCE COMPLEX AT LEFT BACKGROUND. VIEW TO SOUTHEAST. - San Francisco National Cemetery, 1 Lincoln Boulevard, San Francisco, San Francisco County, CA

164

Na+-K+ Pump Regulation and Skeletal Muscle Contractility  

NSDL National Science Digital Library

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

MD Torben Clausen (University of Aarhus Department of Physiology)

2003-10-01

165

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

166

Expression of the Na /Ca2 Exchanger Ameliorates  

E-print Network

- dependent Ca2 uptake confirmed the functional ex- pression of the protein. When NCX1.4 expressing cells (NO is to use antisense oligonucleotides to reduce the expression of the exchanger (16). It was found that Na

167

Na2MoO2As2O7.  

PubMed

Disodium molybdenum dioxide diarsenate, Na2MoO2As2O7, has been synthesized by a solid-state reaction. The structure is built up from MoAs2O12 linear units sharing corners to form a three-dimensional framework containing tunnels running along the a-axis direction in which the Na(+) cations are located. In this framework, the As(V) atoms are tetra-hedrally coordinated and form an As2O7 group. The Mo(VI) atom is displaced from the center of an octa-hedron of O atoms. Two Na(+) cations are disordered about inversion centres. Structural relationships between different compounds: A2MoO2As2O7 (A = K, Rb), AMOP2O7 (A = Na, K, Rb; M = Mo, Nb) and MoP2O7 are discussed. PMID:23468669

Jouini, Raja; Zid, Mohamed Faouzi; Driss, Ahmed

2012-12-01

168

Redetermination of Na(3)TaF(8).  

PubMed

The crystal structure of trisodium octafluoridotantalate, Na(3)TaF(8), has been redetermined using diffractometer data collected at 153 K, resulting in more accurate bond distances and angles than obtained from a previous structure determination based on film data. The structure is built from layers running along [101], which are formed by distorted [TaF(8)] antiprisms and [NaF(6)] rectangular bipyramids sharing edges and corners. The individual layers are separated by eight-coordinated Na ions. Two atoms in the asymmetric unit are in special positions: the Ta atom is on a twofold axis in Wyckoff position 4e and one of the Na ions lies on an inversion centre in Wyckoff site 4d. PMID:20814090

Langer, Vratislav; Smrcok, Lubomír; Boca, Miroslav

2010-09-01

169

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

170

NaIrO3—A 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

171

High capacity Na+/H+ exchange activity in mineralizing osteoblasts.  

PubMed

Osteoblasts synthesize bone in polarized groups of cells sealed by tight junctions. Large amounts of acid are produced as bone mineral is precipitated. We addressed the mechanism by which cells manage this acid load by measuring intracellular pH (pHi) in non-transformed osteoblasts in response to weak acid or bicarbonate loading. Basal pHi in mineralizing osteoblasts was ? 7.3 and decreased by ? 1.4 units upon replacing extracellular Na(+) with N-methyl-D-glucamine. Loading with 40 mM acetic or propionic acids, in normal extracellular Na(+), caused only mild cytosolic acidification. In contrast, in Na(+) -free solutions, weak acids reduced pHi dramatically. After Na(+) reintroduction, pHi recovered rapidly, in keeping with Na(+) /H(+) exchanger (NHE) activity. Sodium-dependent pHi recovery from weak acid loading was inhibited by amiloride with the Ki consistent with NHEs. NHE1 and NHE6 were expressed strongly, and expression was upregulated highly, by mineralization, in human osteoblasts. Antibody labeling of mouse bone showed NHE1 on basolateral surfaces of all osteoblasts. NHE6 occurred on basolateral surfaces of osteoblasts mainly in areas of mineralization. Conversely, elevated HCO?3- alkalinized osteoblasts, and pH recovered in medium containing Cl(-), with or without Na(+), in keeping with Na(+) -independent Cl(-) /HCO?3- exchange. The exchanger AE2 also occurred on the basolateral surface of osteoblasts, consistent with Cl(-) /HCO?3- exchange for elimination of metabolic carbonate. Overexpression of NHE6 or knockdown of NHE1 in MG63 human osteosarcoma cells confirmed roles of NHE1 and NHE6 in maintaining pHi. We conclude that in mineralizing osteoblasts, slightly basic basal pHi is maintained, and external acid load is dissipated, by high-capacity Na(+) /H(+) exchange via NHE1 and NHE6. PMID:21413028

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

2011-06-01

172

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 (17±2 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

173

NMR Studies of Phase Transitions. II. NaCN  

Microsoft Academic Search

The 23Na nuclear magnetic resonance absorption has been observed in the cubic phase of polycrystalline NaCN between about 15° and 170°C, but could not be detected in the orthorhombic phase which forms below 10.5°C. The observed lineshape and its second moment S are compatible with a model in which S=Sd+Sq0+Sq(T) , where Sd and Sq0 are temperature-independent terms, Sd?0.39 G2

C. K. Coogan; H. S. Gutowsky

1964-01-01

174

Kinetic characterization of Na,K-ATPase inhibition by Eosin  

PubMed Central

Eosin is a probe for the Na pump nucleotide site. In contrast to previous studies examining eosin effects on Na only ATPase, we examined Na,K ATPase and K activated pNPPase activity in red blood cell membranes and purified renal Na,K ATPase. At saturating ATP (3mM) the eosin IC50 for Na pump inhibition was 19uM. Increasing ATP concentrations (0.2 – 2.5 mM) did not overcome eosin-induced inhibition thus eosin is a mixed-type inhibitor of ATPase activity. To test if eosin can bind to the high affinity ATP site, purified Na,K ATPase was labeled with 20 uM FITC. With increasing eosin concentrations (0.1 uM – 10 uM) the incorporation of FITC into the ATP site significantly decreases suggesting that eosin prevents FITC reaction at the high affinity ATP site. Eosin was a more potent inhibitor of K activated phosphatase activity than of Na,K ATPase activity. At 5mM pNPP the eosin IC50 for Na pump inhibition was 3.8 ± 0.23 uM. Increasing pNPP concentrations (0.45 – 14.5 mM) did not overcome eosin-induced inhibition thus eosin is a mixed-type inhibitor of pNPPase activity. These results can be fit by a model in which eosin and ATP bind only to the nucleotide site; in some pump conformations, this site is rigid and the binding is mutually exclusive and in other conformations, the site is flexible and able to accommodate both eosin and ATP (or pNPP). Interestingly, eosin inhibition of pNPPase became competitive after the addition of C12E8 (0.1%) but the inhibition of ATPase remained mixed. PMID:17331759

Ogan, Jeffrey T.; Reifenberger, Matthew S.; Milanick, Mark A.; Gatto, Craig

2007-01-01

175

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

176

Neutral Phospholipids Stimulate Na,K-ATPase Activity  

PubMed Central

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

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

2013-01-01

177

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; Müller, Volker

2013-02-01

178

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

179

23Na and 1H NMR Microimaging of Intact Plants  

NASA Astrophysics Data System (ADS)

23Na NMR microimaging is described to map, for the first time, the sodium distribution in living plants. As an example, the response of 6-day-old seedlings of Ricinus communis to exposure to sodium chloride concentrations from 5 to 300 mM was observed in vivo using 23Na as well as 1H NMR microimaging. Experiments were performed at 11.75 T with a double resonant 23Na- 1H probehead. The probehead was homebuilt and equipped with a climate chamber. T1 and T2 of 23Na were measured in the cross section of the hypocotyl. Within 85 min 23Na images with an in-plane resolution of 156 × 156 ?m were acquired. With this spatial information, the different types of tissue in the hypocotyl can be discerned. The measurement time appears to be short compared to the time scale of sodium uptake and accumulation in the plant so that the kinetics of salt stress can be followed. In conclusion, 23Na NMR microimaging promises great potential for physiological studies of the consequences of salt stress on the macroscopic level and thus may become a unique tool for characterizing plants with respect to salt tolerance and salt sensitivity.

Olt, Silvia; Krötz, Eva; Komor, Ewald; Rokitta, Markus; Haase, Axel

2000-06-01

180

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

181

thin films grown with additional NaF layers  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

182

Temperature-dependent chemical shift and relaxation times of (23)Na in Na(4)HTm[DOTP].  

PubMed

We describe the characterization of a (23)Na temperature-dependent chemical shift and relaxation rates in the complex, Na(4)HTm[DOTP]. This is the first characterization of a (23)Na temperature-dependent chemical shift in a nonmetallic sample. The (23)Na temperature-dependent chemical shift coefficient is approximately -0. 5 PPM/ degrees C for both an aqueous solution and a 6% agarose gel of this compound. This is 50 times the magnitude of the temperature-dependent chemical shift coefficient of water protons. The relaxation times, T(1), T(2f), and T(2s) increased by 0.1, 0.01, and 0.05 ms/ degrees C, respectively. Applications of these unique properties for designing an MRI technique for monitoring heat deposition in tissue and tissue phantoms are discussed. PMID:10698662

Shapiro, E M; Borthakur, A; Bansal, N; Leigh, J S; Reddy, R

2000-03-01

183

Temperature-Dependent Chemical Shift and Relaxation Times of 23Na in Na 4HTm[DOTP  

NASA Astrophysics Data System (ADS)

We describe the characterization of a 23Na temperature-dependent chemical shift and relaxation rates in the complex, Na 4HTm[DOTP]. This is the first characterization of a 23Na temperature-dependent chemical shift in a nonmetallic sample. The 23Na temperature-dependent chemical shift coefficient is ˜-0.5 PPM/°C for both an aqueous solution and a 6% agarose gel of this compound. This is 50 times the magnitude of the temperature-dependent chemical shift coefficient of water protons. The relaxation times, T1, T2f, and T2s increased by 0.1, 0.01, and 0.05 ms/°C, respectively. Applications of these unique properties for designing an MRI technique for monitoring heat deposition in tissue and tissue phantoms are discussed.

Shapiro, Erik M.; Borthakur, Arijitt; Bansal, Navin; Leigh, John S.; Reddy, Ravinder

2000-03-01

184

Anisotropy of effective charges in NaNO2, NaNO3, KNO3 and CaCO3  

Microsoft Academic Search

Effective charges of the constituents of NaNO2, NaNO3, KNO3 and CaCO3 are calculated from the splitting of polar optical modes into transverse and longitudinal components, obtained from the simulation of the infrared reflectivity spectra polarised along the different crystallographic directions. Effective charges within planar molecular ions are found to be highly anisotropic, whereas the effective charge of external cations depends

F. Brehat; B. Wyncke; F. Gervais

1989-01-01

185

[Mechanisms for linking high salt intake to vascular tone: role of Na(+) pump and Na(+)/Ca²(+) exchanger coupling].  

PubMed

Excessive salt intake is a major risk factor for hypertension. However, the underlying molecular relationship between salt and hypertension is not fully understood. Recently discovered cardiotonic steroids, such as endogenous ouabain and other steroids, have been proposed as candidate intermediaries. Plasma cardiotonic steroids are significantly elevated in patients with essential hypertension and in salt-dependent hypertensive animals. Generally, it is believed that cardiotonic steroids inhibit Na(+) pump activity and lead to an increase in the cytosolic Na(+) concentration. Cellular Na(+) accumulation raises the cytosolic Ca²(+) concentration through the involvement of Na(+)/Ca²(+) exchanger type 1 (NCX1). In isolated arteries from ?2 Na(+) pump knockout mice (?2(+/-)), myogenic tone is increased, and NCX inhibitor normalizes the elevated myogenic tone in ?2(+/-) arteries. The NCX inhibitor lowers arterial blood pressure in salt-dependent hypertensive rats but not in other types of hypertensive rats or in normotensive rats. Furthermore, smooth muscle-specific NCX1 transgenic mice are hypersensitive to salt, whereas mice with smooth muscle-specific knockout of NCX1 (NCX1(SM-/-)) have low salt sensitivity. These results suggest that functional coupling between the vascular ?2 Na(+) pump and NCX1 is a critical molecular mechanism for salt-induced blood pressure elevation. PMID:21048395

Kita, Satomi; Iwamoto, Takahiro

2010-11-01

186

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

187

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=0.2–0.5?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

188

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

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

2012-01-01

189

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

PubMed Central

The Scn7a gene encodes for the specific sodium channel NaX, which is considered a primary determinant of sodium sensing in the brain. Only partial data exist describing the NaX distribution pattern and the cell types that express NaX in both the rat and mouse brain. To generate a global view of the sodium detection mechanisms in the two rodent brains, we combined NaX immunofluorescence with fluorescent cell markers to map and identify the NaX-expressing cell populations throughout the network involved in hydromineral homeostasis. Here, we designed an anti-NaX antibody targeting the interdomain 2–3 region of the NaX channel’s ?-subunit. In both the rat and mouse, NaX 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. NaX immunostaining was also detected in neurons of the area postrema. In addition to this common NaX expression pattern, several differences in NaX immunostaining for certain structures and cell types were found between the rat and mouse. NaX 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 NaX was only colocalized with vimentin positive cells in the mouse circumventricular organs. In addition, NaX immunostaining was specifically observed in NeuN immunopositive cells in the median preoptic nucleus of the rat. Overall, this study characterized the NaX-expressing cell types in the network controlling hydromineral homeostasis of the rat and mouse. NaX 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

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

2012-01-01

190

NaN, a novel voltage-gated Na channel, is expressed preferentially in peripheral sensory neurons and down-regulated after axotomy  

PubMed Central

Although physiological and pharmacological evidence suggests the presence of multiple tetrodotoxin-resistant (TTX-R) Na channels in neurons of peripheral nervous system ganglia, only one, SNS/PN3, has been identified in these cells to date. We have identified and sequenced a novel Na channel ?-subunit (NaN), predicted to be TTX-R and voltage-gated, that is expressed preferentially in sensory neurons within dorsal root ganglia (DRG) and trigeminal ganglia. The predicted amino acid sequence of NaN can be aligned with the predicted structure of known Na channel ?-subunits; all relevant landmark sequences, including positively charged S4 and pore-lining SS1–SS2 segments, and the inactivation tripeptide IFM, are present at predicted positions. However, NaN exhibits only 42–53% similarity to other mammalian Na channels, including SNS/PN3, indicating that it is a novel channel, and suggesting that it may represent a third subfamily of Na channels. NaN transcript levels are reduced significantly 7 days post axotomy in DRG neurons, consistent with previous findings of a reduction in TTX-R Na currents. The preferential expression of NaN in DRG and trigeminal ganglia and the reduction of NaN mRNA levels in DRG after axonal injury suggest that NaN, together with SNS/PN3, may produce TTX-R currents in peripheral sensory neurons and may influence the generation of electrical activity in these cells. PMID:9671787

Dib-Hajj, S. D.; Tyrrell, L.; Black, J. A.; Waxman, S. G.

1998-01-01

191

TCCN CORE COURSES SFA MAJOR REQUIREMENTS SFA Communication (12 hours) NA No Equivalent CSC 102  

E-print Network

TCCN CORE COURSES SFA MAJOR REQUIREMENTS SFA Communication (12 hours) NA No Equivalent CSC 102 ENGL 1301 Rhetoric & Composition ENG 131 NA No Equivalent CSC 202 ENGL 1302 Research & Argument ENG 132 NA No Equivalent CSC 211 SPCH 1315 Public Speaking COM 111 NA No Equivalent CSC 214 ENGL 2311 Technical Report

Long, Nicholas

192

A novel method to quantify H +-ATPase-dependent Na + transport across plasma membrane vesicles  

Microsoft Academic Search

To prevent sodium toxicity in plants, Na+ is excluded from the cytosol to the apoplast or the vacuole by Na+\\/H+ antiporters. The secondary active transport of Na+ to apoplast against its electrochemical gradient is driven by plasma membrane H+-ATPases that hydrolyze ATP and pump H+ across the plasma membrane. Current methods to determine Na+ flux rely either on the use

Yongqing Yang; Lei Hu; Xuemei Chen; Eric A. Ottow; Andrea Polle; Xiangning Jiang

2007-01-01

193

Links Between Hydrothermal Environments, Pyrophosphate, Na+, and Early Evolution  

NASA Astrophysics Data System (ADS)

The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced phosphorylation of orthophosphate (Pi) to pyrophosphate (PPi) and the capability of PPi to drive energy requiring dark reactions supported PPi as a possible early alternative to ATP. Like the proton-pumping ATPase, the corresponding membrane-bound PPase also is a H+-pump, and like the Na+-pumping ATPase, it can be a Na+-pump, both in archaeal and bacterial membranes. We suggest that PPi and Na+ transport preceded ATP and H+ transport in association with geochemistry of the Earth at the time of the origin and early evolution of life. Life may have started in connection with early plate tectonic processes coupled to alkaline hydrothermal activity. A hydrothermal environment in which Na+ is abundant exists in sediment-starved subduction zones, like the Mariana forearc in the W Pacific Ocean. It is considered to mimic the Archean Earth. The forearc pore fluids have a pH up to 12.6, a Na+-concentration of 0.7 mol/kg seawater. PPi could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates. A key to PPi formation in these geological environments is a low local activity of water.

Holm, Nils G.; Baltscheffsky, Herrick

2011-10-01

194

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

PubMed Central

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

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

2011-01-01

195

Ouabain binding site in a functioning Na+/K+ ATPase.  

PubMed

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

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

2011-11-01

196

Estragole blocks neuronal excitability by direct inhibition of Na+ channels  

PubMed Central

Estragole is a volatile terpenoid, which occurs naturally as a constituent of the essential oils of many plants. It has several pharmacological and biological activities. The objective of the present study was to investigate the mechanism of action of estragole on neuronal excitability. Intact and dissociated dorsal root ganglion neurons of rats were used to record action potential and Na+ currents with intracellular and patch-clamp techniques, respectively. Estragole blocked the generation of action potentials in cells with or without inflexions on their descendant (repolarization) phase (Ninf and N0 neurons, respectively) in a concentration-dependent manner. The resting potentials and input resistances of Ninf and N0 cells were not altered by estragole (2, 4, and 6 mM). Estragole also inhibited total Na+ current and tetrodotoxin-resistant Na+ current in a concentration-dependent manner (IC50 of 3.2 and 3.6 mM, respectively). Kinetic analysis of Na+ current in the presence of 4 mM estragole showed a statistically significant reduction of fast and slow inactivation time constants, indicating an acceleration of the inactivation process. These data demonstrate that estragole blocks neuronal excitability by direct inhibition of Na+ channel conductance activation. This action of estragole is likely to be relevant to the understanding of the mechanisms of several pharmacological effects of this substance. PMID:24345915

Silva-Alves, K.S.; Ferreira-da-Silva, F.W.; Peixoto-Neves, D.; Viana-Cardoso, K.V.; Moreira-Júnior, L.; Oquendo, M.B.; Oliveira-Abreu, K.; Albuquerque, A.A.C.; Coelho-de-Souza, A.N.; Leal-Cardoso, J.H.

2013-01-01

197

Effects of Osmoprotectants upon NaCl Stress in Rice.  

PubMed Central

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

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

1997-01-01

198

Na7Mg13Nd(PO4)12  

PubMed Central

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

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

2012-01-01

199

[The reaction mechanism of Na, K-ATPase].  

PubMed

To help characterize the Na,K-ATPase active site with enzyme incorporated into phospholipid vesicles, the activities with alternative substrates were compared, 22Na/Na-transport was equivalent with ATP, CTP, carbamylphosphate and acetylphosphate, but slower with CTP, 3-O-methylfluoresceinphosphate (3-O-MFP), nitrophenylphosphate and umbelliferonephosphate. It indicates a slower rate of formation of phosphorylating enzyme complex in conformation position of E1 (E1P) when the second group of substrates is bound with enzyme active center. 22Na/K-transport was half as effective with CTP as with ATP and was far slower with the other substrates. It indicates a more stringent selectivity at the low-affinity site of enzyme in conformation E2 that accelerates the slow step of this transport mode. Although enzyme modification with fluoresceinisothiocyanate blocks the high-affinity site to ATP, the K-phosphatase reaction catalyzed by E2 is retained, even with a substrate, 3-O-MFP, that binds to the adenine pocket. Dimethylsulfoxide inhibits hydrolysis of the nucleotides and of the carboxylic phosphate substrates of the K-phosphatase reaction, but stimulates hydrolysis of the phenolic phosphate substrates (nitrophenylphosphate and umbelliferone phosphate) which normally are hydrolyzed more slowly than the other substrates. On the basis of these data the authors propose the model of Na,K-ATPase active center. PMID:2169914

Robinson, J D; Guerra, M; Davis, R L; Steinberg, M

1990-01-01

200

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

201

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

PubMed Central

Dietary potassium (K+) restriction and hypokalemia have been reported to change the abundance of most renal Na+ and K+ transporters and aquaporin-2 isoform, but results have not been consistent. The aim of this study was to reexamine Na+, K+ and H2O transporters' pool size regulation in response to removing K+ from a diet containing 0.74% NaCl, as well as from a diet containing 2% NaCl (as found in American diets) to blunt reducing total diet electrolytes. Sprague-Dawley rats (n = 5–6) were fed for 6 days with one of these diets: 2% KCl, 0.74% NaCl (2K1Na, control chow) compared with 0.03% KCl, 0.74% NaCl (0K1Na); or 2% KCl, 2%NaCl (2K2Na) compared with 0.03% KCl, 2% NaCl (0K2Na, Na+ replete). In both 0K1Na and 0K2Na there were significant decreases in: 1) plasma [K+] (<2.5 mM); 2) urinary K+ excretion (<5% of control); 3) urine osmolality and plasma [aldosterone], as well as 4) an increase in urine volume and medullary hypertrophy. The 0K2Na group had the lowest [aldosterone] (172.0 ± 17.4 pg/ml) and lower blood pressure (93.2 ± 4.9 vs. 112.0 ± 3.1 mmHg in 2K2Na). Transporter pool size regulation was determined by quantitative immunoblotting of renal cortex and medulla homogenates. The only differences measured in both 0K1Na and 0K2Na groups were a 20–30% decrease in cortical ?-ENaC, 30–40% increases in kidney-specific Ste20/SPS1-related proline/alanine-rich kinase, and a 40% increase in medullary sodium pump abundance. The following proteins were not significantly changed in both the 0 K groups: Na+/H+ exchanger isoform 3; Na+-K+-Cl? cotransporter; Na+-Cl? cotransporter, oxidative stress response kinase-1; renal outer medullary K+ channel; autosomal recessive hypercholesterolemia; c-Src, aquaporin 2 isoform; or renin. Thus, despite profound hypokalemia and renal K+ conservation, we did not confirm many of the changes that were previously reported. We predict that changes in transporter distribution and activity are likely more important for conserving K+ than changes in total abundance. PMID:22496411

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

2012-01-01

202

Na 2 SO 4 -induced accelerated oxidation (hot corrosion) of nickel  

Microsoft Academic Search

The Na2SO4-induced accelerated oxidation of nickel has been studied at 1000C. It has been found that low oxygen activities in the Na2SO4, which are produced by the formation of NiO, cause the sulfur activity of the Na2SO4 to be increased. Nickel and sulfur from the Na2SO4 combine to form nickel sulfide and the oxide ion activity of the Na2SO4 is

J. A. Goebel; F. S. Pettit

1970-01-01

203

Salicylic acid alleviates NaCl-induced changes in the metabolism of Matricaria chamomilla plants  

Microsoft Academic Search

Influence of 100 mM NaCl and 50 ?M salicylic acid (SA) and their combination on the metabolism of chamomile (Matricaria chamomilla) during 7 days was studied. NaCl reduced growth and selected physiological parameters and SA in combined treatment (NaCl + SA)\\u000a reversed majority of these symptoms. Application of SA reduced NaCl-induced increase of Na+ in the rosettes, but not in the roots. Accumulation of total

Jozef Ková?ik; Bo?ivoj Klejdus; Josef Hedbavny; Martin Ba?kor

2009-01-01

204

Gamma-ray limits on Na-22 production in novae  

NASA Technical Reports Server (NTRS)

Data accumulated from 1980 to 1987 by the gamma-ray spectrometer aboard the SMM are analyzed to search for annual increases at 1.275 MeV as evidence of Na-22 decay in the Galactic center region and in the ejecta of recent individual novae. No evidence of any 1.275 MeV emission of celestial origin is found. A limit of 3 x 10 to the -6th solar mass is placed on the accumulated Na-22 from many novae occurring near the Galactic center, and a limit of 7 x 10 to the -7th solar mass is placed on the mass of Na-22 ejected by the closest of the recent neon-rich novae.

Leising, Mark D.; Share, Gerald H.; Chupp, Edward L.; Kanbach, Gottfried

1988-01-01

205

Calcium Stearate Thin Films Evaporated onto NaCl  

NASA Astrophysics Data System (ADS)

Crystallographic orientation of calcium stearate thin films evaporated onto cleaved NaCl was investigated as a function of substrate temperature and deposition rate. At substrate temperatures below ˜50°C, needlelike crystallites of calcium stearate were grown epitaxially with their c axis parallel to the < 110> directions of the NaCl substrate (two-directional lateral orientation). At substrate temperatures above ˜70°C, the c axis of the deposited films was normal to the substrate and the [110] calcium stearate was parallel to the < 110> NaCl (normal orientation). One-directional lateral growth, i.e., the c axis of the crystallites is pointing in only one direction, was observed in a relatively large area of the film, most frequently at substrate temperatures between 55 and 65°C.

Okuyama, Katsuro; Tada, Kazuhiro; Ohshima, Shigetoshi

1991-08-01

206

Intrinsic energy resolution of NaI(Tl)1  

NASA Astrophysics Data System (ADS)

The light output for ?10 mm×10 mm and ?75 mm×75 mm NaI(Tl) crystals and energy resolution were measured for ?-ray energies ranging from 16-1333 keV. These measurements enabled the observation of the light yield nonproportionality behavior and allowed the determination of the intrinsic resolution after correcting for the measured resolution for photomultiplier tube (PMT) statistics. The intrinsic resolution was then compared with the nonproportionality component. The latter was calculated using measured electron response, Monte Carlo N Particle code (MCNP4B), and the simplified cascade sequence for NaI(Tl). This comparison allowed the identification of the intrinsic resolution component associated with ?-rays. Consequently, it was shown that the ?-ray component is the most dominant component of the NaI(Tl) intrinsic resolution.

Moszy?ski, M.; Zalipska, J.; Balcerzyk, M.; Kapusta, M.; Mengesha, W.; Valentine, J. D.

2002-05-01

207

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

208

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

209

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

210

Dynamical and Kinetic PropertiesDynamical and Kinetic Properties of the Na+HF Reaction on Twoof the Na+HF Reaction on Two  

E-print Network

the Na+HF Reaction on Two Different Potential EnergyDifferent Potential Energy Surfaces of the Bunker's program. Two potential energy surface (PES) for the gas-phase Na+HF NaF+H reaction were, detailed dynamics properties calculations using two differents Potentital Energy Surface (PES): GSA PES

211

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

212

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.; Blümel, R.; Narducci, F. A.; Smith, W. W.

2015-01-01

213

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

214

Tb/Na tobermorite: Thermal behaviour and high temperature products  

NASA Astrophysics Data System (ADS)

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 3/ m obtaining cell parameters a=9.39199(4) Å and c=6.84041(5) Å. Terbium silicate apatite heated in melted NaF led to Tb 4O 7 crystals.

Garra, Walter; Marchetti, Fabio; Merlino, Stefano

2009-06-01

215

Efficiency of the Modular Neutron Array (MoNA)  

NASA Astrophysics Data System (ADS)

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 11Be 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.; Baumann, T.; Christian, G. A.; Denby, D.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Hall, C. C.; Hinnefeld, J.; Schiller, A.; Strongman, M. J.; Thoennessen, M.

2009-03-01

216

LFV and exotics at the NA62 experiment  

NASA Astrophysics Data System (ADS)

The NA62 experiment at the CERN SPS is aimed at measuring the branching fraction of the ultrarare decay K+ ? ?+vbar v with ~10% precision by collecting ~1013 kaon decays in two years of data taking. This amount of data will allow to carry out a wide program of searching for rare and forbidden (within the Standard Model) K+ and ?0 decays, including sterile neutrinos, lepton flavor violating modes, exotic particles (e.g. "dark photons"). The expected performances of the NA62 setup will allow to improve existing limits for several decay modes.

Duk, Viacheslav

2014-11-01

217

[Nonhyperbolic kinetics of Na,K-ATPase--a new viewpoint].  

PubMed

The kinetics of the 130 kDa monomer obtained by treatment of duck salt gland Na,K-ATPase with C12E8 was compared with that of the membrane-bound enzyme. The shapes of the substrate-velocity curves for the membrane-bound and solubilized forms were quite different: a hyperbolic one for the monomeric Na,K-ATPase and a nonhyperbolic one for the native enzyme. A reaction scheme for ATP hydrolysis based on a comparative analysis of kinetic properties of these two forms is proposed. Experimental evidence in favour of this hypothesis is presented. PMID:1653044

Fedosova, N U; Boldyrev, A A

1991-03-01

218

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

roce 1873 se probl#m#m nekone#n#ch mno#in (motivov#n op#t anal#zou) za#al v#novat Georg Cantor (1845 -- 1918). Vzhledem k tomu, #e mezit#m byla vypracov#na modern# teorie re#ln#ch ##sel (zalo#en# na z#pln#n# ##sel racion#ln#ch), za##nala se r#sovat i praktick# aplikace jeho v#sledk#. G. Cantor je pova#ov#n za

Stanovsky, David

219

Mesospheric Na layer at 40°N: Modeling and observations  

NASA Astrophysics Data System (ADS)

A complete monthly record of the annual variation of Na and temperature in the upper mesosphere has been obtained from 3 years of nighttime lidar observations at two midlatitude sites, Urbana-Champaign, Illinois (40°N), and Fort Collins, Colorado (41°N). The Na density exhibits a strong annual variation at all heights between 81 and 107 km, with the column abundance of the layer peaking in early winter and then decreasing by nearly a factor of 4 to a midsummer minimum. There are also significant semiannual components to the variations in the centroid height and thickness of the layer. The nighttime temperature profile between 81 and 105 km exhibits a high winter mesopause at about 101 km and a summer mesopause at about 85 km. During spring and autumn, the mesopause oscillates apparently randomly between these states. A seasonal model of the Na layer was then constructed incorporating recent laboratory studies of the pertinent neutral and ionic reactions of the metal. The background atmospheric composition was provided from three off-line models, as well as from UARS/Microwave Limb Sounder satellite measurements of H2O. With a small number of permitted adjustable parameters, the model is able to reproduce many observed features of the Na layer remarkably well, including the monthly variation in column abundance and layer shape. The biggest discrepancy is during midsummer, when the modeled layer is displaced 2-3 km above that observed, although a factor contributing to this is that the lidar observing period during summer was relatively short and the effect of the diurnal tide could have been incompletely sampled. Both the observations and the model show that Na density and temperature are highly correlated below 96 km (correlation coefficient equal to 0.8-0.95), mostly as a result of the influence of odd oxygen/hydrogen chemistry on the partitioning of sodium between atomic Na and its principal reservoir species, NaHCO3. Above 96 km, a weak negative correlation (-0.2) is explained by the dominance of ion-molecule chemistry. Finally, it was shown that if the eddy diffusion coefficient in the middle mesosphere is significantly smaller or if the global meteoric influx is much larger than the values used in the present model, then processes for permanently removing gas-phase Na species in the mesosphere, such as polymerisation and deposition onto dust particles, will need to be included.

Plane, John M. C.; Gardner, Chester S.; Yu, Jirong; She, C. Y.; Garcia, Rolando R.; Pumphrey, Hugh C.

1999-02-01

220

Links Between Hydrothermal Environments, Pyrophosphate, Na + , and Early Evolution  

Microsoft Academic Search

The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced phosphorylation\\u000a of orthophosphate (Pi) to pyrophosphate (PPi) and the capability of PPi to drive energy requiring dark reactions supported\\u000a PPi as a possible early alternative to ATP. Like the proton-pumping ATPase, the corresponding membrane-bound PPase also is\\u000a a H+-pump, and like the Na+-pumping ATPase, it can be a Na+-pump,

Nils G. Holm; Herrick Baltscheffsky

2011-01-01

221

Structural Integrity and Microstructure of NA^+ Conducting Ceramics  

NASA Astrophysics Data System (ADS)

Oxides with the general formula of Na1+x Zr2 Six P3-x O12 , known as Nasicon, are fast Na+ ion-conducting materials with important electrochemical applications and many functional properties, often attributed to their unique structural features. Comparative, in situ studies of the limits of structural integrity were performed for selected Nasicon materials, using synchrotron x-ray diffraction and diamond anvil cell technology. We show how different processing conditions produce crystalline structures with specific morphology. We discuss the bulk modulus, the compressibility and the influence of the volume fraction of primary and secondary crystalline phases on the overall Nasicon structural integrity.

Lipinska, Kristina; Kalita, Patricia; Hemmers, Oliver; Sinogeikin, Stanislav; Shebanova, Olga; Yang, Wenge; Mariotto, Gino

2010-03-01

222

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

PubMed

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 Ca(2+) mobilizing signals, in the regulation of neuronal excitability by controlling the activity of ion channels, in the release of neurotransmitters and hormones, as well as in synaptic plasticity and gene transcription. In the present article evidence showing Na(+), K(+)-ATPase involvement in signaling pathways, enzyme changes in diverse neurological diseases as well as during aging, have been summarized. Issues refer mainly to Na(+), K(+)-ATPase studies in ischemia, brain injury, depression and mood disorders, mania, stress, Alzheimer´s disease, learning and memory, and neuronal hyperexcitability and epilepsy. PMID:25018677

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

2014-06-01

223

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, Alzheimer´s disease, learning and memory, and neuronal hyperexcitability and epilepsy. PMID:25018677

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

2014-01-01

224

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

225

Study of resonant scattering of 21Na+p relevant to astrophysical 18Ne(?,p)21Na reaction  

NASA Astrophysics Data System (ADS)

Astrophysical 18Ne(?,p)21Na reaction is one of the most probable breakout routes, which lead to the rp-process from the hot-CNO cycle, converting the initial CNO elements into heavier elements in Type I x-ray bursters. Presently, there is no much experimental cross-section data reported at the energy of astrophysical interest, and resonant spectroscopic information in compound 22Mg is scarce as well. The experiment has been carried out by using the CNS radioactive ion beam separator (CRIB). Resonant properties in 22Mg have been studied via the resonant elastic scattering of 21Na+p, and cross section of the time-reversal reaction of 21Na(p,?)18Ne been measured simultaneously. A wide excitation energy region up to Ex ~ 9.5 MeV in 22Mg has been scanned with a thick-target method. Some preliminary results will be reported.

He, J. J.; Zhang, L. Y.; Xu, S. W.; Chen, S. Z.; Hu, J.; Ma, P.; Chen, R. F.; Yamaguchi, H.; Kubono, S.; Hashimoto, T.; Kahl, D.; Hayakawa, S.; Wakabayashi, Y.; Togano, Y.; Wang, H. W.; Tian, W. D.; Guo, B.; Teranishi, T.; Iwasa, N.; Yamada, T.; Komatsubara, T.

2012-11-01

226

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 2×105 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

227

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

SciTech Connect

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

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

2007-01-01

228

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

NASA Technical Reports Server (NTRS)

A previously reported laboratory determination of the IR spectrum of Na2S is presently noted to have been incorrectly interpreted, due to the inadvertent contamination of the sample with Na2CO3. New Na2S spectra are presented, and the Na2CO3 spectrum is examined in order to demonstrate that this phase is the primary sample contaminant. Na2S is a candidate surface component on the Jupiter satellite, Io, in view of its apparent high IR brightness and spectral neutrality in the 1-5 micron range.

Nash, Douglas B.

1988-01-01

229

Temperature dependence of 23Na NMR quadrupole parameters and spin-lattice relaxation rate in NaNO 2 powder  

Microsoft Academic Search

The nuclear quadrupole coupling constant (e2qQ\\/h) and the spin-lattice relaxation rate (1\\/T1) of 23Na NMR in the NaNO2 powder were investigated by employing a magic angle spinning probe and a wideline probe, respectively, at 9.4T as a function of temperature (T) in the range of 300–458K. The linearity between e2qQ\\/h and the squared spontaneous polarization (Ps2) was obeyed up to

J. K. Jung; O. H. Han; S. H. Choh

1999-01-01

230

Corrosion of Fe alloys in NaNO 3 -KNO 3 NaNO 2 at 823 K  

Microsoft Academic Search

In support of advanced solar central receiver programs, six commercially available, iron-based construction materials were\\u000a exposed to a molten NaNO2-NaNO3-KNO3 salt mixture at 823 K for periods up to six months. After one month of exposure, oxide coatings formed on each alloy;the amount of oxidation ranged from 10 mg\\/cm\\u000a 2\\u000a for low carbon steel to ?0.7 mg\\/cm2 for 310 stainless

C. M. Kramer; W. H. Smyrl; W. B. Estill

1980-01-01

231

Intracellular and extracellular concentrations of Na+ modulate Mg2+ transport in rat ventricular myocytes.  

PubMed

Apparent free cytoplasmic concentrations of Mg2+ ([Mg2+]i) and Na+ ([Na+]i) were estimated in rat ventricular myocytes using fluorescent indicators, furaptra (mag-fura-2) for Mg2+ and sodium-binding benzofuran isophthalate for Na+, at 25 degrees C in Ca2+-free conditions. Analysis included corrections for the influence of Na+ on furaptra fluorescence found in vitro and in vivo. The myocytes were loaded with Mg2+ in a solution containing 24 mM Mg2+ either in the presence of 106 mM Na+ plus 1 mM ouabain (Na+ loading) or in the presence of only 1.6 mM Na+ to deplete the cells of Na+ (Na+ depletion). The initial rate of decrease in [Mg2+]i from the Mg2+-loaded cells was estimated in the presence of 140 mM Na+ and 1 mM Mg2+ as an index of the rate of extracellular Na+-dependent Mg2+ efflux. Average [Na+]i, when estimated from sodium-binding benzofuran isophthalate fluorescence in separate experiments, increased from 12 to 31 mM and 47 mM after Na+ loading for 1 and 3 h, respectively, and decreased to approximately 0 mM after 3 h of Na+ depletion. The intracellular Na+ loading significantly reduced the initial rate of decrease in [Mg2+]i, on average, by 40% at 1 h and by 64% at 3 h, suggesting that the Mg2+ efflux was inhibited by intracellular Na+ with 50% inhibition at approximately 40 mM. A reduction of the rate of Mg2+ efflux was also observed when Na+ was introduced into the cells through the amphotericin B-perforated cell membrane (perforated patch-clamp technique) via a patch pipette that contained 130 mM Na+. When the cells were heavily loaded with Na+ with ouabain in combination with intracellular perfusion from the patch pipette containing 130 mM Na+, removal of extracellular Na+ caused an increase in [Mg2+]i, albeit at a very limited rate, which could be interpreted as reversal of the Mg2+ transport, i.e., Mg2+ influx driven by reversed Na+ gradient. Extracellular Na+ dependence of the rate of Mg2+ efflux revealed that the Mg2+ efflux was activated by extracellular Na+ with half-maximal activation at 55 mM. These results contribute to a quantitative characterization of the Na+-Mg2+ exchange in cardiac myocytes. PMID:16085772

Tashiro, Michiko; Tursun, Pulat; Konishi, Masato

2005-11-01

232

Intracellular and Extracellular Concentrations of Na+ Modulate Mg2+ Transport in Rat Ventricular Myocytes  

PubMed Central

Apparent free cytoplasmic concentrations of Mg2+ ([Mg2+]i) and Na+ ([Na+]i) were estimated in rat ventricular myocytes using fluorescent indicators, furaptra (mag-fura-2) for Mg2+ and sodium-binding benzofuran isophthalate for Na+, at 25°C in Ca2+-free conditions. Analysis included corrections for the influence of Na+ on furaptra fluorescence found in vitro and in vivo. The myocytes were loaded with Mg2+ in a solution containing 24 mM Mg2+ either in the presence of 106 mM Na+ plus 1 mM ouabain (Na+ loading) or in the presence of only 1.6 mM Na+ to deplete the cells of Na+ (Na+ depletion). The initial rate of decrease in [Mg2+]i from the Mg2+-loaded cells was estimated in the presence of 140 mM Na+ and 1 mM Mg2+ as an index of the rate of extracellular Na+-dependent Mg2+ efflux. Average [Na+]i, when estimated from sodium-binding benzofuran isophthalate fluorescence in separate experiments, increased from 12 to 31 mM and 47 mM after Na+ loading for 1 and 3 h, respectively, and decreased to ?0 mM after 3 h of Na+ depletion. The intracellular Na+ loading significantly reduced the initial rate of decrease in [Mg2+]i, on average, by 40% at 1 h and by 64% at 3 h, suggesting that the Mg2+ efflux was inhibited by intracellular Na+ with 50% inhibition at ?40 mM. A reduction of the rate of Mg2+ efflux was also observed when Na+ was introduced into the cells through the amphotericin B-perforated cell membrane (perforated patch-clamp technique) via a patch pipette that contained 130 mM Na+. When the cells were heavily loaded with Na+ with ouabain in combination with intracellular perfusion from the patch pipette containing 130 mM Na+, removal of extracellular Na+ caused an increase in [Mg2+]i, albeit at a very limited rate, which could be interpreted as reversal of the Mg2+ transport, i.e., Mg2+ influx driven by reversed Na+ gradient. Extracellular Na+ dependence of the rate of Mg2+ efflux revealed that the Mg2+ efflux was activated by extracellular Na+ with half-maximal activation at 55 mM. These results contribute to a quantitative characterization of the Na+-Mg2+ exchange in cardiac myocytes. PMID:16085772

Tashiro, Michiko; Tursun, Pulat; Konishi, Masato

2005-01-01

233

Cesium selectivity of (Al+Na)-substituted tobermorite  

Microsoft Academic Search

Several synthetic tobermorites with different levels of [Al+Na] substitution were prepared from two different types of starting materials and their cation exchange and cesium selective properties were investigated. The substituted tobermorites were found to have high cation exchange capacities and very high selectivities for Cs[sup +] ion. Cesium selectivity of the substituted tobermorites was demonstrated in the presence of divalent

O. P. Shrivastava; S. Komarneni

1994-01-01

234

NaK release model for MASTER-2009  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

235

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

236

BIOLOGICAL SAFETY O N/A Biosafety Cabinets  

E-print Network

BIOLOGICAL SAFETY O N/A Biosafety Cabinets ___BS-1 Grates obstructed ___BS-2 Not certified Exposure Control Plan ___BS-14 Missing BL1/ BL2 / BL2+ posting ___BS-99 Other Biological Safety Finding REGISTRATION __Chemicals __#Autoclave __Ergo __ Biologicals __#BioSafeCabinet __ExposHighVolt __Ionizing Rad

Entekhabi, Dara

237

Optical Attenuation in MoNA and LISA Detector Elements  

NASA Astrophysics Data System (ADS)

The MoNA collaboration is a research group of students and faculty from 13 primarily undergraduate institutions, with detectors at the NSCL: MoNA (Modular Neutron Array) and the newly-built LISA (Large multi-Institutional Scintillating Array). These arrays each have 144 plastic scintillating bars. When a neutron collides with a hydrogen nucleus within the plastic, photomultiplier tubes at either end of the bar detect the scintillation photons. Their arrival times are used to determine the position of the event, but as the light travels through the detector it loses intensity exponentially. How dramatic this loss is can be described by a parameter called the attenuation length, with larger attenuation lengths corresponding to lower loss. Recently the MoNA collaboration conducted its LISA commissioning experiment investigating two-neutron decay states of ^25O. As a part of LISA's commissioning, we measured the attenuation lengths of the individual detector bars that make up the LISA array and compared these lengths with those of the older MoNA array. We found that the LISA bars had a larger attenuation length on average with impacts on detector efficiency and effective threshold.

Rice, Logan; Wong, Jonathan

2011-10-01

238

Grant Title: ITTLESON FOUNDATION Funding Opportunity Number: N/A  

E-print Network

interest are: mental health, AIDS, and the environment. Release and Expiration: N/A Application Deadline-for-profit organizations, dedicated to bettering the United States, and as such, we provide funds for new initiatives. The Foundation's areas of particular interest are: mental health, AIDS, and the environment. For mental health

Farritor, Shane

239

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

240

Luminal Na+/H+ exchange in the proximal tubule  

PubMed Central

The proximal tubule is critical for whole-organism volume and acid–base homeostasis by reabsorbing filtered water, NaCl, bicarbonate, and citrate, as well as by excreting acid in the form of hydrogen and ammonium ions and producing new bicarbonate in the process. Filtered organic solutes such as amino acids, oligopeptides, and proteins are also retrieved by the proximal tubule. Luminal membrane Na+/H+ exchangers either directly mediate or indirectly contribute to each of these processes. Na+/H+ exchangers are a family of secondary active transporters with diverse tissue and subcellular distributions. Two isoforms, NHE3 and NHE8, are expressed at the luminal membrane of the proximal tubule. NHE3 is the prevalent isoform in adults, is the most extensively studied, and is tightly regulated by a large number of agonists and physiological conditions acting via partially defined molecular mechanisms. Comparatively little is known about NHE8, which is highly expressed at the lumen of the neonatal proximal tubule and is mostly intracellular in adults. This article discusses the physiology of proximal Na+/H+ exchange, the multiple mechanisms of NHE3 regulation, and the reciprocal relationship between NHE3 and NHE8 at the lumen of the proximal tubule. PMID:18853182

Bobulescu, I. Alexandru

2010-01-01

241

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; Felicià Plana; Andrés Alastuey; Angel López-Soler

1997-01-01

242

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

243

Hadron yields and hadron spectra from the NA49 experiment  

NASA Astrophysics Data System (ADS)

Preliminary inclusive spectra of negative hadrons, net protons and neutral strange particles are presented, measured by the NA49 experiment in central Pb+Pb collisions at 158 GeV per nucleon. Comparison of their yields with those from the lighter S+S system suggests that the yields scale approximately with the number of participating nucleons.

Jones, P. G.; Afanasiev, S. V.; Alber, T.; Appelshäuser, H.; Bächler, J.; Barnby, L. S.; Bartke, J.; Bia?kowska, H.; Blyth, C. O.; Bock, R.; Bormann, C.; Brady, F. P.; Brockmann, R.; Bunicic, N.; Buncic, P.; Caines, H. L.; Cebra, D.; Chan, P.; Cooper, G. E.; Cramer, J. G.; Cramer, P. B.; Csato, P.; Cyprian, M.; Derado, I.; Dietz, O.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M. I.; Fischer, H. G.; Flierl, D.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gabler, F.; Gal, J.; Ga?dzicki, M.; G?adysz, E.; Grebieszkow, J.; Günther, J.; Harris, J. W.; Hegyi, S.; Hill, L. A.; Huang, I.; Howe, M. A.; Hümmler, H.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P. G.; Kadija, K.; Kolesnikov, V. I.; Kowalski, M.; Lasiuk, B.; Lévai, P.; Malakhov, A. I.; Margetis, S.; Markert, C.; Melkumov, G. L.; Mitchell, J. W.; Mock, A.; Molnár, J.; Nelson, J. M.; Odyniec, G.; Palla, G.; Panagiotou, A. D.; Petridis, A.; Piper, A.; Poskanzer, A. M.; Poziombka, S.; Prindle, D. J.; Pühlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, H. G.; Röhrich, D.; Roland, C.; Roland, G.; Rudolph, H.; Rybicki, A.; Sandoval, A.; Sann, H.; Semenov, A. Yu.; Schäfer, E.; Schmischke, D.; Schmitz, N.; Schönfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Ströbele, H.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T. A.; Trentalange, S.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Weerasundara, D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Yates, T. A.; Zimanyi, J.; Zhu, X.-Z.; Zybert, R.; NA49 Collaboration

1996-02-01

244

Stainless Steel NaK Circuit Integration and Fill Submission  

NASA Technical Reports Server (NTRS)

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

Garber, Anne E.

2006-01-01

245

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.

246

Substituting KCl for NaCl in fresh Queso Fresco  

Technology Transfer Automated Retrieval System (TEKTRAN)

Reducing the sodium level in cheese is challenging when a signature salty flavor is expected, such as in high-moisture Queso Fresco (QF). Fresh starter-free QF was fine milled and dry salted at different levels of NaCl and KCl to obtain total salt levels of 1.5 to 2.0%. The treatments contained 1....

247

Role-Playing Games, Educação e Jogos Computadorizados na Cibercultura  

Microsoft Academic Search

Resumo: Este artigo apresenta a relação entre os RPG e os Jogos Computadorizados aplicados na Educação. O objetivo principal é apresentar o estado da arte e reflexões sobre estes assuntos. Portanto serão apresentadas algumas teorias educacionais que embasam estes temas, além dos principais conceitos de RPG Digitais e como estes jogos estão sendo usados no processo de ensino-aprendizagem. Palavras-chaves: Jogos

João Ricardo Bittencourt; Lucia Maria Giraffa

248

O pleno emprego na perspectiva da modernização reflexiva  

Microsoft Academic Search

Resumo O pleno emprego foi o esteio para a segurança social na Primeira Modernidade. As políticas keynesianas implementadas a partir da crise de 1929 caminharam em direção à composição de um Estado- nacional social. O próprio sucesso do capitalismo industrial provoca mudanças. O desenvolvimento tecnológico, a crescente riqueza e a queda do muro de Berlim impulsionam a sociedade industrial para

Maria do Carmo; Cataldi Muterle

249

Stoichiometric Relationship between Na+ Ions Transported and Glucose Consumed in Human Erythrocytes: Bayesian Analysis of 23Na and 13C NMR Time Course Data  

PubMed Central

We examined the response of Na+,K+-ATPase (NKA) to monensin, a Na+ ionophore, with and without ouabain, an NKA inhibitor, in suspensions of human erythrocytes (red blood cells). A combination of 13C and 23Na NMR methods allowed the recording of intra- and extracellular Na+, and 13C-labeled glucose time courses. The net influx of Na+ and the consumption of glucose were measured with and without NKA inhibited by ouabain. A Bayesian analysis was used to determine probability distributions of the parameter values of a minimalist mathematical model of the kinetics involved, and then used to infer the rates of Na+ transported and glucose consumed. It was estimated that the numerical relationship between the number of Na+ ions transported by NKA per molecule of glucose consumed by a red blood cell was close to the ratio 6.0:1.0, agreeing with theoretical prediction. PMID:23601315

Puckeridge, Max; Chapman, Bogdan E.; Conigrave, Arthur D.; Grieve, Stuart M.; Figtree, Gemma A.; Kuchel, Philip W.

2013-01-01

250

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

251

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

252

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

253

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

NASA Astrophysics Data System (ADS)

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.

254

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; Guillén, Natalia; Levi, Moshe; Sorribas, Víctor

2014-12-15

255

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

256

Tissue kallikrein activation of the epithelial Na channel.  

PubMed

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 (I(Na)) 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; Palmer, Lawrence G

2012-08-15

257

Dehydrogenation reaction for Na-O-H system: a first-principles study.  

PubMed

The crystal structures, electronic, dielectric, and vibrational properties of NaH, Na(2)O and NaOH are systematically investigated by first-principles calculations and the quasiharmonic approximation. The phonon dispersion relations and the phonon density of states of the phases and their thermodynamic functions including the heat capacity, the vibrational enthalpy, and the vibrational entropy are calculated using a direct force-constant method. Based on these results, the dehydrogenation reaction, NaH+NaOH-->H(2)+Na(2)O, is predicted to take place at 528 K, which is in agreement with the experimental observed value. PMID:17705149

Zhang, Xin-Bo; Shi, Si-Qi; Ke, Xue-Zhi; Han, Song; Shioyama, Hiroshi; Kuriyama, Nobuhiro; Kobayashi, Tetsuhiko; Xu, Qiang

2007-09-17

258

Ionic diffusion in voltage-clamped isolated cardiac myocytes. Implications for Na,K-pump studies.  

PubMed Central

The whole-cell voltage-clamp technique employing electrolyte-filled micro-pipette suction electrodes is widely used to investigate questions requiring an electrophysiological approach. With this technique, the ionic composition of the cytosol is assumed to be strongly influenced (as result of diffusion) by the ionic composition of the solution contained in the electrode. If this assumption is valid for isolated cardiac myocytes, the technique would be particularly powerful for studying the dependence of their Na,K-pump on the intracellular [Na+]. However, the relationship between the concentrations of ions in the solution filling the electrode and those in the cytosol has not been established. The relationship was investigated to determine in particular whether the [Na+] at the intracellular cation ligand binding sites for the Na-pump ([ Na+]ps) can be set and clamped by [Na+] in the pipette electrode ([ Na+]pip). If [Na+]pip can set and clamp [Na+]ps, this would provide a means for defining the dependence of the Na,K-pump on intracellular [Na+]. The relationship between [Na+]pip and [Na+]ps was analyzed using two approaches. First, a mathematical model of three-dimensional ionic diffusion within a whole-cell patch-clamped myocyte was developed and the effects of experimental parameters on mean [Na+]ps were investigated. When typical experimental values were simulated, the time course to achieve steady state mean [Na+]ps was found to be most sensitive to variations in electrode pore size, cell length and the Na+ pumping rate, but at steady state, mean [Na+]ps varies from [Na+]pip by 5% or less depending on pump rate. Second, to provide experimental support for the validity of the simulations, isolated ventricular myocytes were voltage-clamped and the reversal potential for the Na current was determined in order to estimate steady state intracellular [Na+]. The results of the mathematical and experimental analyses suggest that steady state [Na+]ps can be regulated by the [Na+] in suction pipette electrodes. These findings, while also having a broader significance, indicate for isolated cardiac myocytes that whole-cell suction micro-electrodes can provide a means to assess the dependence of the Na,K-pump on [Na+]ps. PMID:2551408

Mogul, D J; Singer, D H; Ten Eick, R E

1989-01-01

259

Radiative and nonradiative processes of F and F' centers in NaBr and NaI  

NASA Astrophysics Data System (ADS)

The Dexter et al. criterion for the occurrence of luminescence in deep centers predicts for F centers in NaBr and NaI a strong quenching of the luminescence due to a crossover process between the excited-state- and ground-state-configuration coordinate curves, implying that most optical absorptions do not lead to the relaxed excited state. We have studied the optical absorption, conversion, and emission properties of pure (dilute and concentrated) F-center systems in zone-refined NaBr and NaI with the following results: An infrared emission of double spectral structure is present in both systems, but has very low quantum efficiency (<0.01). A detailed study of the electronic kinetics shows that in the optical excitation cycle all electrons reach the relaxed excited state, from which they can be ionized (thermally or by tunneling) to form F' centers with full efficiency. Therefore, while the above criterion predicts the existence of nonradiative processes properly, the mechanism of crossover reactions is not confirmed, and a nonradiative rate process from the relaxed excited state is strongly suggested. The role of the luminescence due to electron recapture by ionized F centers has been examined, and it is proposed that the second observed luminescence is due to a radiative recapture process from a higher state.

Baldacchini, Giuseppe; Pan, David S.; Lüty, Fritz

1981-08-01

260

Los NIH anuncian el lanzamiento de 3 estudios integrados de medicina de precisión; ALCHEMIST es para pacientes con ciertos tipos de cáncer de pulmón en estadio inicial  

Cancer.gov

Los Estudios sobre la Secuenciación e Identificación de Marcadores para el Mejoramiento de la Terapia Adjuvante para el Cáncer de Pulmón, conocidos con el nombre de ALCHEMIST, identificarán a pacientes con cáncer de pulmón en estadio inicial cuyos tumores albergan ciertos cambios genéticos, y evaluarán si los tratamientos con medicamentos que actúan sobre esos cambios pueden mejorar la supervivencia.

261

Planificación de la transición a la atención en la etapa final de la vida para los pacientes de cáncer en estadio avanzado (PDQ®)  

Cancer.gov

Resumen de información revisada por expertos sobre la preparación necesaria por parte de los proveedores de atención de la salud, los pacientes y sus familas para la transición a la etapa final de la vida en los casos de cáncer en estadio avanzado.

262

Planificación de la transición a la atención en la etapa final de la vida para los pacientes con cáncer en estadio avanzado (PDQ®)  

Cancer.gov

Resumen de información revisada por expertos sobre la preparación necesaria por parte de los proveedores de atención de la salud, los pacientes y sus familas para la transición a la etapa final de la vida en los casos de cáncer en estadio avanzado.

263

INTEX-NA: Intercontinental Chemical Transport Experiment - North America  

NASA Technical Reports Server (NTRS)

INTEX-NA is an integrated atmospheric chemistry field experiment to be performed over North America using the NASA DC-8 and P-3B aircraft as its primary platforms. It seeks to understand the exchange of chemicals and aerosols between continents and the global troposphere. The constituents of interest are ozone and its precursors (hydrocarbons, NOX and HOX), aerosols, and the major greenhouse gases (CO2, CH4, N2O). INTEX-NA will provide the observational database needed to quantify inflow, outflow, and transformations of chemicals over North America. INTEX-NA is to be performed in two phases. Phase A will take place during the period of May-August 2004 and Phase B during March-June 2006. Phase A is in summer when photochemistry is most intense and climatic issues involving aerosols and carbon cycle are most pressing, and Phase B is in spring when Asian transport to North America is at its peak. INTEX-NA will coordinate its activities with concurrent measurement programs including satellites (e. g. Terra, Aura, Envisat), field activities undertaken by the North American Carbon Program (NACP), and other U.S. and international partners. However, it is being designed as a 'stand alone' mission such that its successful execution is not contingent on other programs. Synthesis of the ensemble of observation from surface, airborne, and space platforms, with the help of global/regional models is an important It is anticipated that approximately 175 flight hours for each of the aircraft (DC-8 and P-3B) will be required for each Phase. Principal operational sites are tentatively selected to be Bangor, ME; Wallops Island, VA; Seattle, WA; Rhinelander, WI; Lancaster, CA; and New Orleans, LA. These coastal and continental sites can support large missions and are suitable for INTEX-NA objectives. The experiment will be supported by forecasts from meteorological and chemical models, satellite observations, surface networks, and enhanced O3,-sonde releases. In addition to characterizing Atlantic-outflow and Pacific-inflow, INTEX-NA will characterize air masses transported between the U.S., Canada, and Mexico. INTEX-NA will be the first continental scale inflow, outflow, and transformation experiment to be performed over North America. It will provide the most comprehensive observational data set to date to understand the O3/NOX/HOX/aerosol photochemical system and the carbon cycle. One of the critical needs of the carbon cycle research is to obtain large-scale vertical and horizontal concentration gradients of CO2, throughout the troposphere over continental source/sink regions. INTEX-NA is ideally suited to perform this role. Coastal and continental operational sites will allow us to develop a curtain profile of greenhouse gases (e. g. CO2,) and other key pollutants across North America. Such information is central to our quantitative understanding of chemical budgets on the continental scale. We expect to provide a number of satellite under-flights over land and water to test and validate observations from the appropriate satellite platform (e. g. Aura). We plan to develop strong collaborations with other national and international observational programs. Results from INTEX-NA should directly benefit the development of environmental policy for air quality and climate change.

Singh, Hanwant B.; Jacob, D.; Pfister, L.; Hipskind, R. Stephen (Technical Monitor)

2002-01-01

264

Effects of concanavalin A on Na(+)-dependent and Na(+)-independent mechanisms for H+ extrusion in alveolar macrophages.  

PubMed

Alveolar macrophages (m phi) possess two parallel mechanisms for plasmalemmal H+ extrusion: a V-type H+ pump (V-ATPase) and a Na+/H+ exchanger (NHE). To investigate the coordinated functioning of the H+ extruders for m phi intracellular pH (pHi) regulation, we investigated the effects of the plant lectin concanavalin A (ConA) on resident alveolar m phi from rabbits. ConA (1 microM, 30-min pretreatment) activated the m phi for phagocytosis of opsonized Escherichia coli. ConA activation did not affect the baseline pHi of m phi or the initial rate of pHi recovery (dpHi/dt) from an intracellular acid load (acid-loaded pHi nadir approximately 6.9). However, the contributions of Na(+)-independent H+ transport (i.e. V-ATPase activity) and Na(+)-dependent H+ transport (i.e. NHE activity) to dpHi/dt were altered significantly. The lectin stimulated Na+/H+ exchange and inhibited V-ATPase activity. In control m phi, V-ATPase-mediated H+ extrusion was responsible for > 80% of dpHi/dt. Conversely, in ConA-treated m phi, Na+/H+ exchange was responsible for approximately 65% of dpHi/dt, and V-ATPase activity was responsible for only 35% of dpHi/dt. These results underscore the complex mechanisms and signaling pathways that coordinate the activities of cellular acid-base transporters in m phi pHi regulation. PMID:9436175

Bidani, A; Heming, T A

1998-01-01

265

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

USGS Publications Warehouse

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

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

1991-01-01

266

Studies of high energy cathodes and anodes for molten salt batteries. Progress report, August 1, 1978July 31, 1979. [SClâ\\/sup +\\/ in AlClâ--NaCl\\/Na\\/sup +\\/ ion conductor\\/Na  

Microsoft Academic Search

Research and development on a new rechargeable cell SClâ\\/sup +\\/ in AlClâ--NaCl\\/Na\\/sup +\\/ ion conductor\\/Na is reported. This cell operates at temperatures in the range 220 to 250°C, and has an open circuit voltage of 4.2V. The research during the past year has involved additional electrochemical, spectroelectrochemical, and spectroscopic (Raman and electron spin resonance) studies of sulfur and its oxidation

Mamantov

1979-01-01

267

Stabilization of Na,K-ATPase by ionic interactions.  

PubMed

The effect of ions on the thermostability and unfolding of Na,K-ATPase from shark salt gland was studied and compared with that of Na,K-ATPase from pig kidney by using differential scanning calorimetry (DSC) and activity assays. In 1 mM histidine at pH 7, the shark enzyme inactivates rapidly at 20 degrees C, as does the kidney enzyme at 42 degrees C (but not at 20 degrees C). Increasing ionic strength by addition of 20 mM histidine, or of 1 mM NaCl or KCl, protects both enzymes against this rapid inactivation. As detected by DSC, the shark enzyme undergoes thermal unfolding at lower temperature (Tm approximately 45 degrees C) than does the kidney enzyme (Tm approximately 55 degrees C). Both calorimetric endotherms indicate multi-step unfolding, probably associated with different cooperative domains. Whereas the overall heat of unfolding is similar for the kidney enzyme in either 1 mM or 20 mM histidine, components with high mid-point temperatures are lost from the unfolding transition of the shark enzyme in 1 mM histidine, relative to that in 20 mM histidine. This is attributed to partial unfolding of the enzyme due to a high hydrostatic pressure during centrifugation of DSC samples at low ionic strength, which correlates with inactivation measurements. Addition of 10 mM NaCl to shark enzyme in 1 mM histidine protects against inactivation during centrifugation of the DSC sample, but incubation for 1 h at 20 degrees C prior to addition of NaCl results in loss of components with lower mid-point temperatures within the unfolding transition. Cations at millimolar concentration therefore afford at least two distinct modes of stabilization, likely affecting separate cooperative domains. The different thermal stabilities and denaturation temperatures of the two Na,K-ATPases correlate with the respective physiological temperatures, and may be attributed to the different lipid environments. PMID:18187035

Fodor, Elfrieda; Fedosova, Natalya U; Ferencz, Csilla; Marsh, Derek; Pali, Tibor; Esmann, Mikael

2008-04-01

268

The positions of H+, Li+ and Na+ impurities in beryl  

NASA Astrophysics Data System (ADS)

Electron Paramagnetic Resonance (EPR) measurements show that Li+ impurities are located at two different positions in beryl, one in the crystal lattice and the other in the crystal channel. The position of the Li+ impurity in the lattice is generally assumed to be at the site of a missing Be2+ ion. It is shown that this is not the case, but that the Li+ ion is located in a tetrahedron formed by the oxygens of one side of the Be tetrahedron and the nearest oxygen in the channel ring. This Li site has the coordinates (0.423, 0.344, 0.167) and can only be occupied when the neighbouring Be site is empty. There are four such sites around every Be tetrahedron at the distance of 1.46 Å from the Be site. The distance from the Li site to the oxygens of the Li tetrahedron is 1.84 Å. This compares favourably with the much smaller distance of 1.65 Å in the Be tetrahedron. Protons in beryl are trapped at or near these Li sites. Na+ is known to be located at the 2b position at the center of the silicate rings, where it is stabilized by one water molecule located at each of the two surrounding 2a sites. This is also the position of Li+ in the beryl channel. It is found that the presence of Na+ in the ring of six oxygens reduces the radius of this ring. The Na+ impurity has also been supposed to be located at position 2a alone and at 2b stabilized by only one water molecule. It is now proposed that Na+ and H2O are located together in the Al Be plane when only one water molecule is associated with Na+. The water oxygen is located at or near 2a and Na is closer to the Be site in tetrahedral beryl and closer to the Al site in octahedral beryl. It is proposed that the water protons are also located in the Al Be plane, which would mean that there exists a third type of water in beryl. The origin of protons and OH- ions in beryl is discussed and it is suggested that the plugs in the beryl channels are CO{3/2-} ions. Diffusion of OH- ions and natural radiation may have led to the creation of NO3 and the blue colour of Maxixe beryl.

Andersson, Lars Olov

2006-09-01

269

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 ...

270

Na+(Li+)/H+ antiporter in Pseudomonas aeruginosa and effect of Li+ on cell growth.  

PubMed

Everted membrane vesicles were prepared from cells of Pseudomonas aeruginosa, and cation/H+ antiport was measured. We observed activities of Na+/H+ antiport, Li+/H+ antiport and K+/H+ antiport. Judging from the competition pattern, it seems that there are at least two types of antiporter, a Na+(Li+)/H+ antiporter and a K+/H+ antiporter. Na+ was a good substrate for the Na+(Li+)/H+ system, whereas Li+ was a poor substrate. Although the K(m) value for Na+ (or Li+) was similar to those in Escherichia coli Na+/H+ antiporters, the Vmax value for Na+ (or Li+) was much smaller in the P. aeruginosa antiporter than in the E. coli antiporters. Growth of P. aeruginosa was strongly inhibited by 0.4 M LiCl, but not by NaCl or KCl. PMID:9212978

Inaba, K; Utsugi, J; Kuroda, T; Tsuda, M; Tsuchiya, T

1997-06-01

271

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

E-print Network

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

Farritor, Shane

272

Both Na+-K+ ATPase and Na +-H+ exchanger are immediately active upon post-ischemic reperfusion in isolated rat hearts.  

PubMed

Limited time resolution has hampered proper evaluation of changes in intracellular Na+ (Na+i) in whole hearts upon post-ischemic reperfusion. In isolated rat hearts perfused at 37 degrees C, we studied the contribution of the Na+-K+ ATPase and the Na+-H+ exchanger to control of Na+i during reperfusion using 23Na NMR and the shift reagent Tm(DOTP)5- with a time resolution of 5 s. To assess activities of the Na +-K+ ATPase and the Na+-H+ exchanger, 250 micro mol/l ouabain and/or 3 micro mol/l EIPA, respectively, was added to the perfusate during the first 5 min of reperfusion, following 20 min of ischemia. When used, ouabain was also present for 2 min prior to ischemia. Na+i increased during ouabain perfusion prior to ischemia (132+/-5 and 133+/-4% of the pre-ischemic control value after 2 min, in ouabain and ouabain+EIPA hearts, respectively; mean+/-s.e.m.; n=6 per group) resulting in higher end-ischemic values in ouabain and ouabain+EIPA hearts (249+/-9 and 267+/-17% of the pre-ischemic control value, respectively) than in control and EIPA hearts (207+/-21 and 199+/-10% of the pre-ischemic control value, respectively). In ouabain, hearts Na+i started to rise directly upon reperfusion and amounted to 117+/-6% of the end-ischemic value after 60 s of reperfusion. In control hearts, however, Na+i dropped immediately and was 87+/-5% of the end-ischemic value after 60 s, indicating that the Na+-K+ ATPase resumed function directly upon reperfusion. The initial steep increase of Na+i upon reperfusion in ouabain hearts, which diminished after approximately 40 s to the rate of increase observed during ischemia, was absent in ouabain + EIPA hearts. This indicates the existence, although masked by Na+-K+ ATPase activity, of a Na+-H + exchange mediated Na+ influx upon reperfusion. If only EIPA was present during reperfusion the initial decrease in Na+i was faster than in control hearts, corroborating this finding. PMID:9515010

Van Emous, J G; Schreur, J H; Ruigrok, T J; Van Echteld, C J

1998-02-01

273

Cesium selectivity of (Al+Na)-substituted tobermorite  

SciTech Connect

Several synthetic tobermorites with different levels of [Al+Na] substitution were prepared from two different types of starting materials and their cation exchange and cesium selective properties were investigated. The substituted tobermorites were found to have high cation exchange capacities and very high selectivities for Cs[sup +] ion. Cesium selectivity of the substituted tobermorites was demonstrated in the presence of divalent cations such as Ca[sup 2+], Mg[sup 2+], Ba[sup 2+] and univalent cations such as Na[sup +], K[sup +] and Li[sup +] which are one hundred times more concentrated than the cesium ion. The uptake of Cs is maximum in the presence of highly hydrated Mg[sup 2+] and Li[sup +] ions whereas it is minimum in the presence of less hydrated K[sup +] and Ba[sup 2+] ions due to steric limitations of the tobermorite structure.

Shrivastava, O.P.; Komarneni, S. (Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.)

1994-01-01

274

Homeostatic function of astrocytes: Ca2+ and Na+ signalling  

PubMed Central

The name astroglia unifies many non-excitable neural cells that act as primary homeostatic cells in the nervous system. Neuronal activity triggers multiple homeostatic responses of astroglia that include increase in metabolic activity and synthesis of neuronal preferred energy substrate lactate, clearance of neurotransmitters and buffering of extracellular K+ ions to name but a few. Many (if not all) of astroglial homeostatic responses are controlled by dynamic changes in the cytoplasmic concentration of two cations, Ca2+ and Na+. Intracellular concentration of these ions is tightly controlled by several transporters and can be rapidly affected by the activation of respective fluxes through ionic channels or ion exchangers. Here, we provide a comprehensive review of astroglial Ca2+ and Na+ signalling. PMID:23243501

Parpura, Vladimir; Verkhratsky, Alexei

2012-01-01

275

Lipid-protein interactions in neurotropic Na-pump regulation.  

PubMed

The role of lipid-protein interaction in the regulation of the brain Na-pump by different neurotropic agents (prostaglandin E2, middle molecules from blood plasma of uremic patients, neuropeptide galanin, the oligopeptide fraction from brain) was investigated. We established a definite correlation between the lipid status (the peroxidativity of the lipids, the phospholipids and cholesterol content) of the Na,K-ATPase enzyme preparation (plasma membrane fragments) and the influence of the neurotropic agents. Besides, after the treatment with delipidative agents (phospholipase A2, SDS) the inhibitory effects of these neurotropic agents, were diminished significantly. These facts do not contradict our previous suggestion that the lipid-protein interactions underlay the regulative action mechanism of the natural bioactive ligands. PMID:1280397

Laasik, J; Sillard, R; Langel, U; Zilmer, M

1992-01-01

276

Modeling neutron events in MoNA-LISA using MCNPX  

NASA Astrophysics Data System (ADS)

The MoNA-LISA collaboration uses time-of-flight techniques and charged particle detectors to determine the structure of exotic nuclei such as ^24O and ^12Be. To determine the decay energy in particular, a neutron that hits the Modular Neutron Array and the Large multi-Institutional Scintillator Array has its energy, position and angle of incidence recorded if and only if the charged particle detector system detects an appropriate charged-particle fragment. However, the analysis uses only the first neutron to hit the detector array even in the case of 2n events, since the data acquisition system cannot distinguish between simultaneous but random 2n events and events due to 2n reactions. We are using MCNPX to model the reaction channels possible in the MoNA-LISA detector system in an effort to better improve the resolution on decay energy spectra for events with multiple neutrons.

Kendra Elliston, Margaret; Peters, Alexander; Stryker, Kristen; Stephenson, Sharon

2011-10-01

277

Performance comparison of MoNA and LISA neutron detectors  

NASA Astrophysics Data System (ADS)

In 2002 eight primarily undergraduate institutions constructed and tested the Modular Neutron Array (MoNA) which has been used to detect high energy neutrons at the National Superconducting Cyclotron Laboratory (NSCL). Nine institutions have now designed, constructed and tested the Large-area multi-Institutional Scintillator Array (LISA) neutron detector which will be used at the NSCL and the future Facility for Rare Isotope Beams (FRIB). Both detectors are comprised of 144 detector modules. Each module is a 200 x 10 x 10 cm^3 bar organic plastic scintillator with a photomultiplier tube mounted on each end. Using cosmic rays and a gamma source, we compared the performance of MoNA and LISA by using the same electronics to check light attenuation, position resolution, rise times, and cosmic ray peak widths. Results will be presented.

Purtell, Kimberly; Rethman, Kaitlynne; Haagsma, Autumn; Finck, Joseph; Smith, Jenna; Snyder, Jesse

2010-11-01

278

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.

Ramírez-Piscina, L.; Sancho, J. M.

2014-12-01

279

Concentrations of Na+ and Cl- in transplacental ultrafiltrate in sheep.  

PubMed Central

1. Maternal blood was made transiently hypertonic by rapid I.V. infusion of a concentrated mannitol solution into pregnant ewes bearing lambs with an indwelling flow sensor and vascular catheters. 2. The transplacental flows of water and of Na+ and Cl- were calculated from the umbilical arteriovenous differences in the concentrations of 125I-labelled albumin and electrolytes, and the fetal placental blood flow. 3. The reflection coefficients of Na+ and Cl- were calculated by means of the Patlak equation and found to be 0.85 +/- 0.04 and 0.68 +/- 0.04 (means +/- S.E.M.). The filtration coefficient was 1.02 x 10(-7) +/- 0.12 x 10(-7) cm5 dyne-1 s-1. 4. The results fitted best to an equivalent pore radius in the placental barrier smaller than the currently accepted 0.44 nm but not less than 0.35 nm. PMID:7473245

Faber, J J; Anderson, D F

1995-01-01

280

Precision measurement of kaon radiative decays at NA48  

NASA Astrophysics Data System (ADS)

The kaon decays are an excellent laboratory to test low energy strong interaction perturbative theories. Recent results on radiative K ± decays from CERN NA48/2 experiment are presented. In the channel K???? more than a million reconstructed decays have lead to the precision measurement of both the direct photon emission and inner bremsstrahlung amplitudes, with their interference term being observed for the first time. In addition the CP violating asymmetry between K + and K - has been obtained to be less than 10 in this channel. We also report on the measurement of the branching fraction of the rare decay K???? using more than 1000 events from 20% of the full NA48/2 data set. From the spectrum of ?? mass the decay parameter ? has been extracted with unprecedented precision. We measure in a model independent way the decay rate of the process K??ee?, never observed before, using 120 events.

Biino, Cristina

2011-01-01

281

Na-irradiated alpha-quartz: chemical epitaxy and luminescence  

NASA Astrophysics Data System (ADS)

Doping of ?-quartz by ion implantation leads to amorphization even at low fluences, but subsequent annealing in air or oxygen can restore the crystalline order (chemical epitaxy). Here we report on measurements of RBS channeling and cathodoluminescence (CL) spectra during chemical epitaxy of ?-quartz irradiated with 50-keV Na-ions and annealed in 18O2-gas. In particular, the variation of the damage profile and CL spectra (the latter taken at 10 K and 300 K) as functions of the ion fluence will be discussed. The CL spectra at 10 K are dominated by a 2.90-eV band and differ greatly from the ones taken at 300 K; the intensity of this band increases strongly with the Na ion fluence. Some conclusions concerning the underlying photoactive defect structures will be drawn.

G?siorek, S.; Lieb, K. P.; Sahoo, P. K.; Keinonen, J.

2008-10-01

282

Membrane Na+-pyrophosphatases can transport protons at low sodium concentrations.  

PubMed

Membrane-bound Na(+)-pyrophosphatase (Na(+)-PPase), working in parallel with the corresponding ATP-energized pumps, catalyzes active Na(+) transport in bacteria and archaea. Each ~75-kDa subunit of homodimeric Na(+)-PPase forms an unusual funnel-like structure with a catalytic site in the cytoplasmic part and a hydrophilic gated channel in the membrane. Here, we show that at subphysiological Na(+) concentrations (<5 mM), the Na(+)-PPases of Chlorobium limicola, four other bacteria, and one archaeon additionally exhibit an H(+)-pumping activity in inverted membrane vesicles prepared from recombinant Escherichia coli strains. H(+) accumulation in vesicles was measured with fluorescent pH indicators. At pH 6.2-8.2, H(+) transport activity was high at 0.1 mM Na(+) but decreased progressively with increasing Na(+) concentrations until virtually disappearing at 5 mM Na(+). In contrast, (22)Na(+) transport activity changed little over a Na(+) concentration range of 0.05-10 mM. Conservative substitutions of gate Glu(242) and nearby Ser(243) and Asn(677) residues reduced the catalytic and transport functions of the enzyme but did not affect the Na(+) dependence of H(+) transport, whereas a Lys(681) substitution abolished H(+) (but not Na(+)) transport. All four substitutions markedly decreased PPase affinity for the activating Na(+) ion. These results are interpreted in terms of a model that assumes the presence of two Na(+)-binding sites in the channel: one associated with the gate and controlling all enzyme activities and the other located at a distance and controlling only H(+) transport activity. The inherent H(+) transport activity of Na(+)-PPase provides a rationale for its easy evolution toward specific H(+) transport. PMID:24158447

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

2013-12-01

283

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

284

Photoinduced Phenomena in Na2S-GeS2 Glasses  

NASA Astrophysics Data System (ADS)

Composition dependence of physical properties and photoinduced phenomena in ionic chalcogenide glasses, Na2S-GeS2, has been studied. The density, optical gap, and photoinduced phenomena show characteristic changes at around 10Na2S-90GeS2. In the glasses with greater Na2S contents, photoenhanced hydration occurs. Photoinduced birefringence is maximal at 20Na2S-80GeS2. Origins of these features are discussed on the bases of atomic and electronic models.

Tanaka, Keiji; Nemoto, Noriyuki; Nasu, Hiroyuki

2003-11-01

285

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; Lüpfert, C; Grell, E; Fendler, K; Clarke, R J

1999-01-01

286

Ion permeation in normal and batrachotoxin-modified Na+ channels in the squid giant axon  

Microsoft Academic Search

Na + permeation through normal and batrachotoxin (BTX)-modified squid axon Na ÷ channels was characterized. Unmodified and toxin-modified Na ÷ channels were studied simultaneously in outside-out membrane patches using the cut-open axon technique. Current-voltage relations for both normal and BTX- modified channels were measured over a wide range of Na ÷ concentrations and voltages. Channel conductance as a function of

ANA M. CORREA; RAMON LATORRE; FRANCISCO BEZANILLA

1991-01-01

287

O estado-nação moderno na contemporaneidade: uma outra geopolítica  

Microsoft Academic Search

Como resultado da defesa intransigente da lei do mercado, explica-se o recente surgimento de um “novo regime político social”, que metamorfoseou o caráter político dos debates acerca das relações sociais, que ocorriam na esfera pública estatal. Porém, o Estado-nação moderno não desapareceu, como apregoavam os arautos neoliberais. Argumenta-se que a idéia de território, fundamento do Estado, e a lógica das

Vânia Vlach

2008-01-01

288

Standard Model Tests at the NA62 CERN Experiment  

NASA Astrophysics Data System (ADS)

The physics program of the NA62 experiment aims to search for phenomena beyond the Standard Model by measuring the ratio RK = ?(K?eve(?))/?(K??v?(?)) and studying the ultra rare decay K+??+vv¯. The status of the RK analysis based on ˜40% of the data collected during 2007 and 2008 is summarized and the proposed detector layout to measure the branching ratio of the K+??+vv¯ decay is described.

Bifani, Simone

2010-02-01

289

Nanoindentation Study of Na-Geopolymers Exposed to High Temperatures  

Microsoft Academic Search

This paper reports the usefulness of nanoindentation as a characterization and monitoring tool for studying thermal behaviour\\u000a of Geopolymer materials. The influence of the manufacturing process of Na-Geopolymers in their micro-mechanical properties\\u000a and thermal behaviour has been studied. Two types of metakaolin-based geopolymer panels with almost identical composition\\u000a were prepared by injection and pouring methods. Micro-mechanical properties of the two

I. Beleña; W. Zhu

2009-01-01

290

Rate limitation of the Na(+),K(+)-ATPase pump cycle.  

PubMed Central

The kinetics of Na(+)-dependent phosphorylation of the Na(+),K(+)-ATPase by ATP were investigated via the stopped-flow technique using the fluorescent label RH421 (saturating [ATP], [Na(+)], and [Mg(2+)], pH 7.4, and 24 degrees C). The well-established effect of buffer composition on the E(2)-E(1) equilibrium was used as a tool to investigate the effect of the initial enzyme conformation on the rate of phosphorylation of the enzyme. Preincubation of pig kidney enzyme in 25 mM histidine and 0.1 mM EDTA solution (conditions favoring E(2)) yielded a 1/tau value of 59 s(-1). Addition of MgCl(2) (5 mM), NaCl (2 mM), or ATP (2 mM) to the preincubation solution resulted in increases in 1/tau to values of 129, 167, and 143 s(-1), respectively. The increases can be attributed to a shift in the enzyme conformational equilibrium before phosphorylation from the E(2) state to an E(1) or E(1)-like state. The results thus demonstrate conclusively that the E(2) --> E(1) transition does in fact limit the rate of subsequent reactions of the pump cycle. Based on the experimental results, the rate constant of the E(2) --> E(1) transition under physiological conditions could be estimated to be approximately 65 s(-1) for pig kidney enzyme and 90 s(-1) for enzyme from rabbit kidney. Taking into account the rates of other partial reactions, computer simulations show these values to be consistent with the turnover number of the enzyme cycle (approximately 48 s(-1) and approximately 43 s(-1) for pig and rabbit, respectively) calculated from steady-state measurements. For enzyme of the alpha(1) isoform the E(2) --> E(1) conformational change is thus shown to be the major rate-determining step of the entire enzyme cycle. PMID:11566779

Lüpfert, C; Grell, E; Pintschovius, V; Apell, H J; Cornelius, F; Clarke, R J

2001-01-01

291

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. Amaré; S. Cebrián; C. Cuesta; E. García; C. Ginestra; M. Martínez; M. A. Oliván; Y. Ortigoza; A. Ortiz de Solórzano; C. Pobes; J. Puimedón; M. L. Sarsa; J. A. Villar; P. Villar

2015-01-16

292

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

293

Reexamination of the photodissociation of NaH  

SciTech Connect

We have recalculated the photodissociation cross section of NaH as a function of photon wavelength for the X {sup 1}{sigma}{yields}B {sup 1}{pi} transition using the time-independent Fermi golden rule. We have made an attempt to clarify the discrepancy between a recent calculation where the time-dependent autocorrelation function was employed and an earlier one where the Fermi golden rule was used.

Ghosh, Swaralipi; Bhattacharyya, S.S.; Saha, Samir [Atomic and Molecular Physics Section, Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)

2003-05-01

294

MoNA and Two-Neutron Decay Analysis  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) is a large, high-efficiency position-sensitive neutron detector array housed at the National Superconducting Cyclotron Laboratory at Michigan State University, consisting of 144 2-meter long scintillator bars with a PMT positioned at each end, designed to detect the energy and trajectory of fast neutrons emitted in the breakup of exotic neutron-rich nuclei. Because a single neutron can scatter multiple times within MoNA, (including a large presence of dark-scattering from Carbon), the experimental challenge to distinguish between single and multiple neutron decay events is significant. We've developed special data-sorting routines that selectively filter on a combination of factors such as neutron velocity and scattering angle, hit-pattern distribution, neutron-fragment opening angle, and decay energy in order to reduce the Carbon scattering background and enhance correlations between pairs of neutrons. We've applied this analysis to the 2-neutron decays of ^24O and ^13Li from data sets from previous MoNA experiments. Results will be presented.

Grovom, Amanda; Aulie, Alegra; Rogers, Warren F.

2010-11-01

295

Observation of Feshbach resonances between ultracold Na and Rb atoms  

NASA Astrophysics Data System (ADS)

Absolute ground-state ^23Na^87Rb molecule has a large electric dipole moment of 3.3 Debye and its two body exchange chemical reaction is energetically forbidden at ultracold temperatures. It is thus a nice candidate for studying quantum gases with dipolar interactions. We have built an experiment setup to investigate ultracold collisions between Na and Rb atoms as a first step toward the production of ground state molecular samples. Ultracold mixtures are first obtained by evaporative cooling of Rb and sympathetic cooling of Na. They are then transferred to a crossed dipole trap and prepared in different spin combinations for Feshbach resonance study. Several resonances below 1000 G are observed with both atoms prepared in either |F = 1, mF= 1> or |F = 1, mF= -1> hyperfine states. Most of them are within 30 G of predicted values^ based on potentials obtained by high quality molecular spectroscopy studies. This work is supported by RGC Hong Kong. E. Tiemann, private communications

Wang, Fudong; Xiong, Dezhi; Li, Xiaoke; Wang, Dajun

2013-03-01

296

Regulation of cell survival by Na+/H+ exchanger-1.  

PubMed

Na(+)/H(+) exchanger-1 (NHE1) is a ubiquitous plasma membrane Na(+)/H(+) exchanger typically associated with maintenance of intracellular volume and pH. In addition to the NHE1 role in electroneutral Na(+)/H(+) transport, in renal tubular epithelial cells in vitro the polybasic, juxtamembrane NHE1 cytosolic tail domain acts as a scaffold, by binding with ezrin/radixin/moesin (ERM) proteins and phosphatidylinositol 4,5-bisphosphate, which initiates formation of a signaling complex that culminates in Akt activation and opposition to initial apoptotic stress. With robust apoptotic stimuli renal tubular epithelial cell NHE1 is a caspase substrate, and proteolytic cleavage may permit progression to apoptotic cell death. In vivo, genetic or pharmacological NHE1 loss of function causes renal tubule epithelial cell apoptosis and renal dysfunction following streptozotocin-induced diabetes, ureteral obstruction, and adriamycin-induced podocyte toxicity. Taken together, substantial in vivo and in vitro data demonstrate that NHE1 regulates tubular epithelial cell survival. In contrast to connotations of NHE1 as an unimportant "housekeeping" protein, this review highlights that NHE1 activity is critical for countering tubular atrophy and chronic renal disease progression. PMID:18480176

Schelling, Jeffrey R; Abu Jawdeh, Bassam G

2008-09-01

297

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

298

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

299

Membrane potential responses of paramecium caudatum to external Na+.  

PubMed

The membrane potential responses of Paramecium caudatum to Na+ ions were examined to understand the mechanisms underlying the sensation of external inorganic ions in the ciliate by comparing the responses of the wild type and the behavioral mutant. Wild-type cells exhibited initial continuous backward swimming followed by repeated transient backward swimming in the Na+-containing test solution. A wild-type cell impaled by a microelectrode produced initial action potentials and a sustained depolarization to an application of the test solution. The prolonged depolarization, the depolarizing afterpotential, took place subsequently after stimulation. The ciliary reversal of the cell was closely associated with the depolarizing responses. When the application of the test solution was prolonged, the wild-type cell produced sustained depolarization overlapped by repeated transient depolarization. A behavioral mutant defective in the Ca2+ channel, CNR (caudatum non reversal), produced a sustained depolarization but no action potential or depolarizing afterpotential. The mutant cell responded to prolonged stimulation with sustained depolarization overlapped by transient depolarization, although it did not show backward swimming. The results suggest that Paramecium shows at least two kinds of membrane potential responses to Na+ ions: a depolarizing afterpotential mediating initial backward swimming and repeated transient depolarization responsible for the repeated transient backward swimming. PMID:15572860

Oami, Kazunori; Takahashi, Mihoko

2004-11-01

300

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; Lefèvre, Cathérine M T; Heidtmann, Hannelore; Gründer, Stefan

2014-09-01

301

Computer simulation of the response of frog skin epidermis to changes in [Na + ] 0  

Microsoft Academic Search

Summary The operation of the multicompartmental frog skin epidermal model 10E described in the preceding paper was tested to find out by computer simulation whether it responds to changes in [Na+] in the same manner as frog skin. In the range from 5 to 115mm [Na+]0, the rate of net Na+ flux across skin is known to increase. The results

Ernst G. Huf; John R. Howell

1974-01-01

302

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

303

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

304

Potential curves for Na2/+/ and resonance charge transfer cross sections.  

NASA Technical Reports Server (NTRS)

A mode potential method, applied earlier to the positively charged diatomic lithium molecule Li2(+), is used to calculate the six lowest potential energy curves of Na2(+). Charge transfer cross sections are calculated for Li(+) on Li and for Na(+) on Na and found to be in reasonable agreement with experiment.

Bottcher, C.; Allison, A. C.; Dalgarno, A.

1971-01-01

305

NaCl on 8-bit AVR Microcontrollers Michael Hutter1  

E-print Network

NaCl on 8-bit AVR Microcontrollers Michael Hutter1 and Peter Schwabe2 1 Graz University of the Networking and Cryp- tography library (NaCl) on the 8-bit AVR family of microcontrollers. We show that Na curves, Curve25519, Ed25519, Salsa20, Poly1305, AVR, ATmega. 1 Introduction This paper describes

306

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

307

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

PubMed Central

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

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

2009-01-01

308

Stimulation of Transepithelial Na + Current by Extracellular Gd 3+ in Xenopus laevis Alveolar Epithelium  

Microsoft Academic Search

In the present study we investigated the effect of extracellular gadolinium on amiloride-sensitive Na + current across Xenopus alveolar epithelium by Ussing chamber experiments and studied its direct effect on epithelial Na + channels with the patch-clamp method. As observed in various epithelia, the short-circuit current ( I sc) and the amiloride-sensitive Na + current ( I ami) across Xenopus

M. Fronius; W. Clauss; M. Schnizler

2003-01-01

309

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

310

[Effects of NaCl and Na2CO3 stresses on the growth and photosynthesis characteristics of Morus alba seedlings].  

PubMed

Taking 1-year old Morus alba variety 'Qinglong' seedlings as test materials, this paper studied their growth and photosynthetic characteristics under the stresses of different concentration neutral salt NaCl and alkali salt Na2CO3. Salt stresses decreased the plant height and the leaf number, biomass, and photosynthetic capacity of the seedlings markedly. With increasing concentration Na+, the leaf stomatal conductance, transpiration rate, net photosynthetic rate, actual photochemical efficiency, electron transport rate, and photochemical quenching (qP) decreased obviously, the energy dissipation rate increased, and the light use efficiency and photosynthetic capacity dropped down. At low concentrations Na+ (< 150 mmol x L(-1)), the seedlings growth and leaf photosynthetic capacity were slightly inhibited, and the adaptability of the seedlings to the salt stresses increased via the increase of root/shoot ratio. However, this protection mechanism was impaired by increasing salt concentration. Na2CO3 stress (Na+ concentration > 50 mmol x L(-)) had stronger inhibitory effects on the seedlings growth and leaf photosynthetic capacity, and the effect increased with increasing Na+ concentration. It was concluded that at Na+ concentration < 150 mmol x L(-1), the photosynthetic adaptability of M. alba to neutral salt stress was mainly dependent on the plant morphology and photosynthetic metabolism, but at Na+ concentration > 150 mmol x L(-1), the photosynthetic adaptability of M. alba to alkali salt stress was mainly dependent on the photosynthetic metabolism. PMID:22720603

Zhang, Hui-Hui; Zhang, Xiu-Li; Li, Xin; Ding, Jun-Nan; Zhu, Wen-Xu; Qi, Fei; Zhang, Ting; Tian, Ye; Sun, Guang-Yu

2012-03-01

311

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

PubMed Central

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

2000-01-01

312

Improvement of two-step K+-Na+ and Ag+-Na+ ion-exchanged glass waveguides by surface removal  

NASA Astrophysics Data System (ADS)

We introduce a simple approach to improve the properties of waveguides fabricated by two-step K+-Na+ and Ag+-Na+ ion exchange in BK7 glass. By etching a 0.25-?m-thick layer off the waveguide surface, the propagation losses and polarization dependent losses caused by silver colloids formed during the ion exchange process can be significantly reduced. In addition, this method can improve the uniformity of the waveguides with varying waveguide patterns. After 24 h of annealing at 300 °C, the propagation losses of the etched waveguides have a value of 0.25-0.35dB/cm, which is about 0.1dB/cm lower than the waveguides without etch. The etch has little impact on the waveguide mode profiles.

Zou, Jizuo; Chen, Ray T.

2006-02-01

313

Electrochemical Behavior of Silicon in the (NaCl-KCl-NaF-SiO2) Molten Salt  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of silicon was investigated in a molten salts system including saturation silicon dioxide. Silicon was electrodeposited and MoSi2 was formed on the employed molybdenum working electrode by the diffusivities of silicon and the substrate metals. Transient electrochemical techniques such as cyclic voltammetry and chronoamperometry were used to study the reaction mechanism at the molybdenum electrode. Cyclic voltammograms showed the possibility of electrodeposition of Si at -0.64 V versus Pt reference electrode in a NaCl-KCl-NaF-SiO2 system at 1073 K (800 °C). The electrodeposition of Si is single-step charge-transfer process and the cathode process is irreversible. Chronoamperometry studies indicated that electrocrystallization of Si is controlled by progressive nucleation with a three-dimensional growth mechanism.

Cai, Zongying; Li, Yungang; He, Xiaofeng; Liang, Jinglong

2010-10-01

314

Modeling the sorption dynamics of NaH using a reactive force field  

SciTech Connect

We have parametrized a reactive force field for NaH, ReaxFF{sub NaH}, against a training set of ab initio derived data. To ascertain that ReaxFF{sub NaH} is properly parametrized, a comparison between ab initio heats of formation of small representative NaH clusters with ReaxFF{sub NaH} was done. The results and trend of ReaxFF{sub NaH} are found to be consistent with ab initio values. Further validation includes comparing the equations of state of condensed phases of Na and NaH as calculated from ab initio and ReaxFF{sub NaH}. There is a good match between the two results, showing that ReaxFF{sub NaH} is correctly parametrized by the ab initio training set. ReaxFF{sub NaH} has been used to study the dynamics of hydrogen desorption in NaH particles. We find that ReaxFF{sub NaH} properly describes the surface molecular hydrogen charge transfer during the abstraction process. Results on heat of desorption versus cluster size shows that there is a strong dependence on the heat of desorption on the particle size, which implies that nanostructuring enhances desorption process. To gain more insight into the structural transformations of NaH during thermal decomposition, we performed a heating run in a molecular dynamics simulation. These runs exhibit a series of drops in potential energy, associated with cluster fragmentation and desorption of molecular hydrogen. This is consistent with experimental evidence that NaH dissociates at its melting point into smaller fragments.

Ojwang, J. G. O.; Santen, Rutger van; Kramer, Gert Jan [Schuit Institute of Catalysis, Eindhoven University of Technology, Postbus 513, 5600 MB, Den Dolech 2, Eindhoven (Netherlands); Duin, Adri C. T. van; Goddard, William A. III [Material Research Center, California Institute of Technology (Caltech), 1200 East California Boulevard, Pasadena, California 91125 (United States)

2008-04-28

315

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 Wikström, 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; Wikström, M

1996-03-28

316

Regulation of Na(+)-K+ pump activity in contracting rat muscle.  

PubMed Central

1. In rat soleus muscle, high frequency electrical stimulation produced a rapid increase in intracellular Na+ (Na+i) content. This was considerably larger in muscles contracting without developing tension than in muscles contracting isometrically. During subsequent rest a net extrusion of Na+ took place at rates which, depending on the frequency and duration of stimulation, approached the maximum transport capacity of the Na(+)-K+ pumps present in the muscle. 2. In isometrically contracting muscles, the net extrusion of Na+ continued for up to 10 min after stimulation, reducing Na+i to values 30% below the resting level (P < 0.001). This undershoot in Na+i, seen in both soleus and extensor digitorum longus muscles, could be maintained for up to 30 min and was blocked by ouabain or cooling to 0 degree C. 3. The undershoot in Na+i could be elicited by direct stimulation as well as by tubocurarine-suppressible stimulation via the motor endplate. It could not be attributed to a decrease in Na+ influx, to effects of noradrenaline or calcitonin gene-related peptide released from nerve endings, to an increase in extracellular K+ or the formation of nitric oxide. 4. The results indicate that excitation rapidly activates the Na(+)-K+ pump, partly via a change in its transport characteristics and partly via an increase in intracellular Na+ concentration. This activation allows an approximately 20-fold increase in the rate of Na+ efflux to take place within 10 s. 5. The excitation-induced activation of the Na(+)-K+ pump may represent a feed-forward mechanism that protects the Na(+)-K+ gradients and the membrane potential in working muscle. Contrary to previous assumptions, the Na(+)-K+ pump seems to play a dynamic role in maintenance of excitability during contractile activity. PMID:9379412

Nielsen, O B; Clausen, T

1997-01-01

317

Temperature dependence of 23Na NMR quadrupole parameters and spin-lattice relaxation rate in NaNO 2 powder  

NASA Astrophysics Data System (ADS)

The nuclear quadrupole coupling constant (e 2qQ/h) and the spin-lattice relaxation rate (1/ T1) of 23Na NMR in the NaNO 2 powder were investigated by employing a magic angle spinning probe and a wideline probe, respectively, at 9.4 T as a function of temperature ( T) in the range of 300-458 K. The linearity between e 2qQ/h and the squared spontaneous polarization ( Ps2) was obeyed up to near the critical temperature ( Tc=437 K), which is consistent with the previous reports. Moreover, the asymmetry parameter ( ?) at 23Na site is found to be linear with Ps, firstly noticed in this work. The linearity between ln[(1/ T1) reo/(1- Ps2)(1- Ps)] and 1/ T is found to be satisfied up to near the Tc, where (1/ T1) reo is the relaxation rate for the reorientational motion of the NO 2-. From this linearity, the reorientational motion of NO 2- ion in powder samples is found to have an activation energy, ? U=0.22±0.01 eV, which is in good agreement with the value obtained with single crystals.

Jung, J. K.; Han, O. H.; Choh, S. H.

1999-05-01

318

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, we studied the formation of its chloride complexes by UV-Vis spectroscopy as a function of the NaCl concentration at 25 C. The experiments were performed at constant ionic strength by varying the concentration ratio of NaCl and NaClO{sub 4}. Deconvolution resulted in single component absorption spectra for UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0}. The apparent stability constants of UO{sub 2}Cl{sup +} and UO{sub 2}Cl{sub 2}{sup 0} are at different ionic strengths and the experimental data are used to parameterize using the SIT approach.

Paviet-Hartmann, P.; Lin, M.R.; Runde, W.H.

1998-11-30

319

Search for solid conductors of Na/+/ and K/+/ ions - Five new conductors  

NASA Technical Reports Server (NTRS)

Five new conductors of positive Na and K ions, for use as separators in high energy secondary batteries, have been discovered. They include: (1) the pyrochlores NaTaWO6 and NaTa2O5F; (2) the bcc form of NaSbO3; and (3) the niobates 2Na2O-3Nb2O5 and 2K2O-3Nb2O5, with the alkali ions probably in open layers of the completely determined structure. On the basis of approximately 40 structure types, generalizations have been made regarding the relation between structure and ionic transport.

Singer, J.; Kautz, H.; Fielder, W.; Fordyce, J.

1975-01-01

320

The action of Na+ as a cofactor in the inhibition by cytoplasmic protons of the cardiac Na(+)-Ca2+ exchanger in the guinea-pig.  

PubMed Central

1. Na(+)-Ca2+ exchange current was activated in giant excised patches of guinea-pig cardiac sarcolemma by raising the intracellular sodium concentration ([Na+]i). When the pHi was simultaneously acidified to 6.4, the current was transient, dropping by 80% in 30 s. 2. Pre-exposure to a pHi of 6.4 for 15 s reduced the peak Na(+)-Ca2+ exchange current without altering the decay rate or steady-state current. Recovery from proton inhibition was seen when [Na+]i was removed for 9 s. 3. A mathematical model of Na(+)-Ca2+ exchange function reproduced the experimental results. In addition, two model-dependent predictions were seen experimentally. (i) [Na+]i-dependent 'inactivation' of Na(+)-Ca2+ exchange may arise from pHi effects. We observed experimentally that pre-exposure to acidic pHi can remove the transient current component attributed to [Na+]i-dependent 'inactivation'. (ii) self-exchange should be inhibited by acidification. This has been observed by other investigators. 4. We have hypothesized that there are two components to inhibition of the Na(+)-Ca2+ exchanger by intracellular protons, and that one is enhanced by increased [Na+]i (Doering & Lederer, 1993b). This hypothesis is supported by the data presented here and by a model of Na(+)-Ca2+ exchange behaviour in which binding of intracellular sodium to the exchanger enhances the affinity of the exchanger for inhibitory intracellular protons. PMID:7853229

Doering, A E; Lederer, W J

1994-01-01

321

Relations between excitability and contractility in rat soleus muscle: role of the Na+-K+ pump and Na+/K+ gradients  

PubMed Central

The effects of reduced Na+/K+ gradients and Na+-K+ pump stimulation on compound action potentials (M waves) and contractile force were examined in isolated rat soleus muscles stimulated through the nerve. Exposure of muscles to buffer containing 85 mM Na+ and 9 mM K+ (85 Na+/9 K+ buffer) produced a 54 % decrease in M wave area and a 50 % decrease in tetanic force compared with control levels in standard buffer containing 147 mM Na+ and 4 mM K+. Subsequent stimulation of active Na+-K+ transport, using the ?2-adrenoceptor agonist salbutamol, induced a marked recovery of M wave area and tetanic force (to 98 and 87 % of the control level, respectively). Similarly, stimulation of active Na+-K+ transport with insulin induced a significant recovery of M wave area and tetanic force. During equilibration with 85 Na+/9 K+ buffer and after addition of salbutamol there was a close linear correlation between M wave area and tetanic force (r = 0·92, P< 0·001). Similar correlations were found in muscles where tetrodotoxin was used to reduce excitability and in muscles fatigued by 120 s of continuous stimulation at a frequency of 30 Hz. These results show a close correlation between excitability and tetanic force. Furthermore, in muscles depressed by a reduction in the Na+/K+ gradients, ?-adrenergic stimulation of the Na+-K+ pump induces a recovery of excitability which can fully explain the previously demonstrated recovery of tetanic force following Na+-K+ pump stimulation. Moreover, the data indicate that loss of excitability is an important factor in fatigue induced by high-frequency (30 Hz) stimulation. PMID:10373703

Overgaard, Kristian; Nielsen, Ole Bækgaard; Flatman, John A; Clausen, Torben

1999-01-01

322

?-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; Clément, Raphaële J; Armstrong, A Robert; Canales-Vázquez, Jesús; Rozier, Patrick; Grey, Clare P; Bruce, Peter G

2014-12-10

323

Nuclear Na+/K+-ATPase plays an active role in nucleoplasmic Ca2+ homeostasis  

PubMed Central

Summary Na+/K+-ATPase, an integral membrane protein, has been studied for over a half century with respect to its transporter function in the plasma membrane, where it expels three Na+ ions from the cell in exchange for two K+ ions. In this study, we demonstrate a functioning Na+/K+-ATPase within HEK293 cell nuclei. This subcellular localization was confirmed by western blotting, ouabain-sensitive ATPase activity of the nuclear membrane fraction, immunocytochemistry and delivery of fluorescently tagged Na+/K+-ATPase ?- and ?-subunits. In addition, we observed an overlap between nuclear Na+/K+-ATPase and Na/Ca-exchanger (NCX) when nuclei were immunostained with commercially available Na+/K+-ATPase and NCX antibodies, suggesting a concerted physiological coupling between these transporters. In keeping with this, we observed an ATP-dependent, strophanthidin-sensitive Na+ flux into the nuclear envelope (NE) lumen loaded with the Na-sensitive dye, CoroNa-Green. Analogous experiments using Fluo-5N, a low affinity Ca2+ indicator, demonstrated a similar ATP-dependent and strophanthidin-sensitive Ca2+ flux into the NE lumen. Our results reveal an intracellular physiological role for the coordinated efforts of the Na+/K+-ATPase and NCX to actively remove Ca2+ from the nucleoplasm into the NE lumen (i.e. the nucleoplasmic reticulum). PMID:23077175

Galva, Charitha; Artigas, Pablo; Gatto, Craig

2012-01-01

324

Imaging of intracellular sodium with shift reagent aided (23)Na CSI in isolated rat hearts.  

PubMed

23Na chemical shift imaging (CSI) in conjunction with shift reagents was used to obtain images of intracellular (Na(i)) and extracellular sodium (Na(e)) in isolated rat hearts. It was demonstrated that the increase of Na(i) concentration in ischemic myocardium can be detected with this technique. 3D acquisition-weighted (23)Na CSI datasets with a nominal spatial resolution of 1.7 x 1.7 x 2.9 mm were acquired in 30 min in normoxic hearts and in globally or locally ischemic hearts. The shift reagent Tm(DOTP)(5-) was used to discriminate Na(i) and Na(e) signals. Na(i) maps could be generated in ischemic hearts, but not in normoxic hearts as the signal-to-noise ratio is too low. The Na(i) signal increased by more than 100% and the Na(e) signal decreased by more than 50% in myocardium of globally ischemic hearts (n = 3) compared to normoxic hearts (n = 3). In hearts with an acute occlusion of the left anterior descending coronary artery (n = 3), there was a local Na(i) signal increase in the anterior wall in the range of 60-110% compared to remote, normoxic tissue. PMID:12111935

Weidensteiner, Claudia; Horn, Michael; Fekete, Elsbeth; Neubauer, Stefan; von Kienlin, Markus

2002-07-01

325

Relationships among sodium current, permeability, and Na activities in control and glucocorticoid-stimulated rabbit descending colon.  

PubMed

Effects of a potent synthetic glucocorticoid, methylprednisolone (MP), on transepithelial Na transport were examined in rabbit descending colon. Current-voltage (I-V) relations of the amiloride-sensitive apical Na entry pathway were measured in colonic tissues of control and MP-treated (40 mg im for 2 days) animals. Tissues were bathed mucosally by solutions of various Na activities, (Na)m, ranging from 6.2 to 75.6 mM, and serosally by a high K solution. These I-V relations conformed to the "constant field" flux equation permitting determination of the permeability of the apical membrane to Na, PmNa, and the intracellular Na activity, (Na)c. The following empirical relations were observed for both control and MP-treated tissues: Na transport increases hyperbolically with increasing (Na)m obeying simple Michaelis-Mentin kinetics; PmNa decreased hyperbolically with increasing (Na)m, but was unrelated to individual variations in (Na)c; (Na)c increased hyperbolically with (Na)m; both spontaneous and steroid-stimulated variations in Na entry rate could be attributed entirely to parallel variations in PmNa at each mucosal Na activity. Comparison of these empirical, kinetic relations between control and MP-treated tissues revealed: maximal Na current and PmNa were greater in MP tissues, but the (Na)m's at which current and PmNa were half-maximal were markedly reduced; (Na)c was significantly increased in MP tissues at each (Na)m while the (Na)m at half-maximal (Na)c was unchanged. These results provide direct evidence that glucocorticoids cause marked stimulation of Na absorption across rabbit colon primarily by increasing the Na permeability of the apical membrane. While the mechanism for the increased permeability remains to be determined, the altered relation between PmNa and (Na)m suggests possible differences in the conformation or environment of the Na channel in MP-treated tissues. PMID:3761358

Thompson, S M; Sellin, J H

1986-01-01

326

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

327

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

328

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

2014-12-01

329

Study of OSL in NaCl:Cu co-doped with Ca and Ca,P  

NASA Astrophysics Data System (ADS)

New results on photo, thermo and optically stimulated luminescence in NaCl:Cu, NaCl:Ca,Cu and NaCl:Ca,Cu,P are reported. Strong PL, TL is observed in NaCl:C? Initial OSL counts of NaCl:Ca,Cu is approximately 2 times more than that in standard phosphor LMP. The rate of OSL depletion for standard phosphor LMP is only 2.5 times less as compared to that of the NaCl:Cu, NaCl:Ca,Cu. NaCl host thus deserves much more attention than it has received up till now. NaCl:Cu, NaCl:Ca,Cu, NaCl:Ca,Cu,P may be useful as dosimetric materials in online radiation Dosimetry.

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

2013-06-01

330

Na/sup +/-K/sup +/ pump in chronic renal failure  

SciTech Connect

This review summarizes the evidence for the defect in Na/sup +/-K/sup +/ pump in chronic renal failure, considers the role of various factors in causing this defect, and discusses the clinical implications thereof. Intracellular Na is elevated in erythrocytes, leukocytes, and muscle cells from some patients with chronic renal failure (CRF). Recent evidence suggest that this elevation of cell Na may be, in large part, a consequence of decreased number of Na/sup +/-K/sup +/ pump units per cell. Maintenance dialysis over a period of weeks ameliorates the defect in intracellular Na/sup +/, and this improvement is contemporaneous with an increase in the number of Na/sup +/-K/sup +/ pump sites per cell. In erythrocytes with normal cell Na/sup +/, acute hemodialysis increases the rate of /sup 22/Na/sup +/ and /sup 42/K/sup +/ transport. Many factors such as the presence of retained toxic metabolite or circulating inhibitor in the uremic plasma, or biochemical changes produced by acute hemodialysis, may explain this finding. In cells with high cell Na/sup +/, the pump-mediated /sup 42/K/sup +/ transport is normalized at the expense of a raised cell Na/sup +/. The decreased muscle membrane potential in uremic subjects has been attributed to a decreased activity of Na/sup +/-K/sup +/ pump. The authors discuss the role of hormonal abnormalities and circulating inhibitors, which may cause an acute inhibition of the pump and of other factors such as K/sup +/ depletion, which may cause more chronic alterations. The implications of alteration of Na/sup +/ and K/sup +/ pump transport and raised cell Na/sup +/ on other non-pump-mediated transport pathways are discussed. Raised cell Na/sup +/ may be a marker for the adequacy of maintenance dialysis in patients with end-stage renal failure.

Deepak, K.; Kahn, T.

1987-05-01

331

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 50 mmol L(-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 10 mmol L(-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

332

Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution  

PubMed Central

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

2013-01-01

333

Regulation kinetics of Na+-Ca2+ exchange current in guinea-pig ventricular myocytes  

PubMed Central

To investigate the regulation of native cardiac Na+-Ca2+ exchange by cytoplasmic Na+ (Na+i) and Ca2+ (Ca2+i), we recorded the Na+-Ca2+ exchange current (INa-Ca) from inside-out ‘macro patches’ excised from intact guinea-pig ventricular cells. The half-maximal concentration (Kh) of Ca2+i required to induce an inward INa-Ca was 7 ?M. The Kh of Na+i required to induce an outward INa-Ca was 21 mM, and tended to decrease at the steady state of Na+-dependent inactivation. The time constant (?) of Na+-dependent inactivation was ?1.5 s at 100 mM Na+i and 1 ?M Ca2+i. The Kh for Na+i was 14 mM. Ca2+i augmented the peak outward INa-Ca (Kh = 0.2 ?M) and attenuated Na+-dependent inactivation (Kh = 2.2 ?M). The outward INa-Ca was activated by 5 ?M Ca2+i with a half-time to reach steady state (t½) of ?0.4 s. This activation was composed of two exponential processes. Deactivation of the current upon Ca2+i removal also consisted of two exponential processes and had a t½ of ?0.5 s. A Na+-Ca2+ exchange model, consisting of one consecutive 4Na+:1Ca2+ exchange cycle and two inactive states, well mimicked the experimental data with regard to ion dependencies and regulation kinetics. These data provide detailed information on the kinetics of the Na+i- and Ca2+i-dependent regulation of native Na+-Ca2+ exchange. They also indicate that the regulation kinetics operate faster in macro patches than in the giant membrane patch from cardiac ‘blebs’, or in Xenopus oocytes expressing a cloned exchanger (NCX1.1).

Fujioka, Yasutada; Hiroe, Koh; Matsuoka, Satoshi

2000-01-01

334

The gasotransmitter hydrogen sulphide decreases Na+ transport across pulmonary epithelial cells  

PubMed Central

BACKGROUND AND PURPOSE The transepithelial absorption of Na+ in the lungs is crucial for the maintenance of the volume and composition of epithelial lining fluid. The regulation of Na+ transport is essential, because hypo- or hyperabsorption of Na+ is associated with lung diseases such as pulmonary oedema or cystic fibrosis. This study investigated the effects of the gaseous signalling molecule hydrogen sulphide (H2S) on Na+ absorption across pulmonary epithelial cells. EXPERIMENTAL APPROACH Ion transport processes were electrophysiologically assessed in Ussing chambers on H441 cells grown on permeable supports at air/liquid interface and on native tracheal preparations of pigs and mice. The effects of H2S were further investigated on Na+ channels expressed in Xenopus oocytes and Na+/K+-ATPase activity in vitro. Membrane abundance of Na+/K+-ATPase was determined by surface biotinylation and Western blot. Cellular ATP concentrations were measured colorimetrically, and cytosolic Ca2+ concentrations were measured with Fura-2. KEY RESULTS H2S rapidly and reversibly inhibited Na+ transport in all the models employed. H2S had no effect on Na+ channels, whereas it decreased Na+/K+-ATPase currents. H2S did not affect the membrane abundance of Na+/K+-ATPase, its metabolic or calcium-dependent regulation, or its direct activity. However, H2S inhibited basolateral calcium-dependent K+ channels, which consequently decreased Na+ absorption by H441 monolayers. CONCLUSIONS AND IMPLICATIONS H2S impairs pulmonary transepithelial Na+ absorption, mainly by inhibiting basolateral Ca2+-dependent K+ channels. These data suggest that the H2S signalling system might represent a novel pharmacological target for modifying pulmonary transepithelial Na+ transport. PMID:22352810

Althaus, M; Urness, KD; Clauss, WG; Baines, DL; Fronius, M

2012-01-01

335

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

336

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

337

Genetic analysis of NaCl tolerance in tomato.  

PubMed

We attempted to find the suitable parents for the development of tomato hybrids for high salt soils by exploiting combining ability, gene action and heterosis. Six salt-tolerant and three salt-intolerant genotypes, along with their 18 F1 crosses, were evaluated at seedling stage under 10 and 15 dS/m (NaCl) salinity stress, compared to the control level of salinity. The experiment was laid out based on a two-way complete randomized design factorial arrangement with two replications; data on root and shoot length, fresh and dry weights, leaf area, plant length, Na(+), K(+) and K(+)/Na(+) concentrations were recorded. There was significant variation within genotypes, lines, testers, crosses, and line × tester interaction for all plant characters studied under normal and two salinity levels. Estimates of combining ability indicated that under low (10 dS/m) and high (15 dS/m) salinities, line BL1176 and tester LO2875 showed significant GCA effects for most of the traits studied. The cross-combinations 6233 × LO2875, CLN2498A x LO2875 and BL1176 × 17902 showed highest SCA values for most of the characters under 10 and 15 dS/m, respectively. Potence ratio showed that under low and high salinities, all the traits showed over dominant type of gene action except leaf area and K(+) concentration (in 10 dS/m) and shoot length, and leaf area (in 15 dS/m). The highest heterosis for most of the parameters was observed in cross-combinations BL1176 × LO2875 and CLN2498A x LO2875. PMID:21948743

Saeed, A; Shahid, M Q; Anjum, S A; Khan, A A; Shakeel, A; Saleem, M F; Saeed, N

2011-01-01

338

Electron capture from aligned Rydberg Na(25p) states.  

NASA Astrophysics Data System (ADS)

The relative charge transfer cross section of singly charged Li^+ ions incident on aligned Rydberg Na(25p) atoms was studied over approach angle ?=0^circ to 360^circ at intermediate projectile velocities. A mixture of Rydberg Na(25p_j) (j=1/2 and 3/2) states is prepared by two-step laser excitation in the presence of a Stark field followed by adiabatic switching to low field in a 16-element Stark barrel.(J.L. Horn et al./), Rev. Sci. Instrum. 69, 4086 (1998). The first laser is tuned to ? = 589.0 nm to excite the Na (3p_3/2) level overlapping all its hyperfine components. The second laser at ? = 411.6 nm is tuned to the electric dipole transition 3p_3/2arrow 25pj in the Stark field ~ 54 V/cm. After excitation the field is switched adiabatically to 1.8 V/cm and rotated through angle ? during 2 ?sec. Li^+ ions are accelerated to reduced velocity tildev = 1.0 to 2.0 where tildev = v_ion/v_n. Capture events are recorded by a CEM. Capture from the aligned Rydberg target is scanned over all angles by varying ? over 360^circ. The cross section shows maxima at 0^circ and 180^circ and minima at 90^circ and 270^circ. The results are described by the capture anisotropy parameter A = (?_0-?_90)/(?0 +?_90), which falls from ~ 0.47 at tildev = 1.0 to 1.2 as tilde v is increased from 1.4 to 2.0. This work was supported by NSF Grant PHY-9704544.

Hwang, Changsu; MacAdam, Keith B.

2001-05-01

339

Potassium, Na+,K+-pumps and fatigue in rat muscle  

PubMed Central

During contractile activity, skeletal muscles undergo a net loss of cytoplasmic K+ to the interstitial space. During intense exercise, plasma K+ in human arterial blood may reach 8 mm, and interstitial K+ 10–12 mm. This leads to depolarization, loss of excitability and contractile force. However, little is known about the effects of these physiological increases in extracellular K+ ([K+]o) on contractile endurance. Soleus muscles from 4-week-old rats were mounted on transducers for isometric contractions in Krebs–Ringer bicarbonate buffer containing 4–10 mm K+, and endurance assessed by recording the rate of force decline during continuous stimulation at 60 Hz. Increasing [K+]o from 4 to 8 or 10 mm and equilibrating the muscles for 40 or 20 min augmented the rate of force decline 2.4-fold and 7.2-fold, respectively (P < 0.001). The marked loss of endurance elicited by exposure to 8 or 10 mm K+ was alleviated or significantly reduced by stimulating the Na+,K+-pumps by intracellular Na+ loading, the ?2-agonist salbutamol, adrenaline, calcitonin gene related peptide, insulin or repeated excitation. In conclusion, excitation-induced increase in [K+]o is an important cause of high-frequency fatigue, and the Na+,K+-pumps are essential for the maintenance of contractile force in the physiological range of [K+]o. Recordings of contractile force during continuous stimulation at 8–10 mm K+ may be used to analyse the effects of agents or conditions influencing the excitability of working isolated muscles. PMID:17673509

Clausen, Torben; Nielsen, Ole Bækgaard

2007-01-01

340

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

341

Enhanced Infrared Surveillance Imaging Report for NA-22  

SciTech Connect

The purpose of this report is to describe our work on enhanced infrared (IR) surveillance using speckle imaging for NA-22. Speckle imaging in this context is an image post-processing algorithm that aims to solve the atmospheric blurring problem of imaging through horizontal or slant path turbulence. We will describe the IR imaging systems used in our data collections and show imagery before and after speckle processing. We will also compare IR imagery with visible wavelength imagery of the same target in the same conditions and demonstrate how going to longer wavelengths can be beneficial in the presence of strong turbulence.

Carrano, C J

2005-10-04

342

Geodetic satellite observations in North American (solution NA-9)  

NASA Technical Reports Server (NTRS)

A new detailed geoidal map with claimed accuracies of plus or minus 2 meters (on land), based on gravimetric and satellite data, was presented. With the new geoid and the orthometric heights given, more reliable height constraints were calculated and applied. The basic purpose of this experiment was to compute the new solution NA9 by defining the origin of the system, from the point of view of error propagation, in the most favorable position applying inner constraints and imposing new weighted height constraints to all of the stations. The major differences with respect to formerly published adjustments are presented.

Mueller, I. I.; Reilly, J. P.; Soler, T.

1972-01-01

343

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

344

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 (São Paulo city, Brazil), responsible for supplying the Brazilian market.

Baptista, T. S.; Zamboni, C. B.; Marcelino, J. R.

2011-08-01

345

Pregled slovenske esejistike na temo slovenske literarne ustvarjalnosti  

E-print Network

. Ferdo Kozak, Stanko Leben, Josip Vidmar. 132–36. Filip KALAN, 1957: Trije predhodniki sodobne dramatike v Jugoslaviji. Naša sodobnost 5/10. Ur. Drago Šega. 865–872. Vinko MöDERNDORFER, 2001: Gledališ?e v ogledalu: gledališka razmišljanja... in travestije: 1986–1998. Maribor: Obzorja. Michel de MONTAIGNE, 1960: Eseji. Izbor. Ljubljana: Mladinska knjiga. Drago ŠEGA, 1951: O preprostih zgodbah. Novi svet 6/6. Ur. Juš Kozak, Ferdo Kozak. Ljubljana: Državna založba Slovenije. 518–535. Tomo VIRK...

Bergles, Katja

2011-02-01

346

New NA48 Results on Kaon and Hyperon Decays  

E-print Network

The NA48 Collaboration has obtained several new results on kaon and neutral hyperon decays. For hyperons we present new, very precise measurements on the Xi0 lifetime and the decay asymmetries of Xi0 -> Lamda gamma and Xi0 -> Sigma0 gamma. On kaon decays, we report on the first observation of the interference term between Inner Bremsstrahlung and Direct Emission in K+- -> pi+- pi0 gamma and on a new, accurate measurement of the form factor slopes in the semileptonic decay KL -> pi+- mu-+ nu.

R. Wanke

2006-10-22

347

NA62 Spectrometer: A Low Mass Straw Tracker  

NASA Astrophysics Data System (ADS)

The NA62 experiment at CERN, aiming at a precision measurement of the ultra-rare decay K+ ? ?+??, relies on kinematical rejection up to 105 (? 1012 is needed in total). One of the limiting factors to achieve this goal is the multiple scattering in the magnetic spectrometer for kaon decay products; therefore an almost massless (?1.5% X0) straw tracker has been designed to operate in vacuum, to be able to install it inside the decay volume. A vacuum tight prototype was built and tested in 2010: efficiency (?99%), rate capability and single straw resolution (?200 ?m) were veri?ed. The construction of the ?rst chamber started in 2011.

Sergi, A.

348

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

349

Energetic aqueous rechargeable sodium-ion battery based on Na2 CuFe(CN)6 -NaTi2 (PO4 )3 intercalation chemistry.  

PubMed

Aqueous rechargeable sodium-ion batteries have the potential to meet growing demand for grid-scale electric energy storage because of the widespread availability and low cost of sodium resources. In this study, we synthesized a Na-rich copper hexacyanoferrate(II) Na2 CuFe(CN)6 as a high potential cathode and used NaTi2 (PO4 )3 as a Na-deficient anode to assemble an aqueous sodium ion battery. This battery works very well with a high average discharge voltage of 1.4 V, a specific energy of 48 Wh kg(-1) , and an excellent high-rate cycle stability with approximately 90 % capacity retention over 1000 cycles, achieving a new record in the electrochemical performance of aqueous Na-ion batteries. Moreover, all the anode, cathode, and electrolyte materials are low cost and naturally abundant and are affordable for widespread applications. PMID:24464957

Wu, Xian-Yong; Sun, Meng-Ying; Shen, Yi-Fei; Qian, Jiang-Feng; Cao, Yu-Liang; Ai, Xin-Ping; Yang, Han-Xi

2014-02-01

350

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 2.0–4.55?V. PMID:24595232

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

2014-01-01

351

Direct Measurements of {sup 22}Na(p,{gamma}){sup 23}Mg Resonances and Consequences for {sup 22}Na Production in Classical Novae  

SciTech Connect

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

Sallaska, A. L.; Wrede, C.; Garcia, A.; Storm, D. W.; Brown, T. A. D.; Snover, K. A. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Ruiz, C.; Ottewell, D. F.; Buchmann, L.; Vockenhuber, C.; Hutcheon, D. A.; Caggiano, J. A. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada)

2010-10-08

352

Nitric oxide regulates cardiac intracellular Na? and Ca²? by modulating Na/K ATPase via PKC? and phospholemman-dependent mechanism.  

PubMed

In the heart, Na/K-ATPase regulates intracellular Na(+) and Ca(2+) (via NCX), thereby preventing Na(+) and Ca(2+) overload and arrhythmias. Here, we test the hypothesis that nitric oxide (NO) regulates cardiac intracellular Na(+) and Ca(2+) and investigate mechanisms and physiological consequences involved. Effects of both exogenous NO (via NO-donors) and endogenously synthesized NO (via field-stimulation of ventricular myocytes) were assessed in this study. Field stimulation of rat ventricular myocytes significantly increased endogenous NO (18 ± 2 ?M), PKC? activation (82 ± 12%), phospholemman phosphorylation (at Ser-63 and Ser-68) and Na/K-ATPase activity (measured by DAF-FM dye, western-blotting and biochemical assay, respectively; p<0.05, n=6) and all were abolished by Ca(2+)-chelation (EGTA 10mM) or NOS inhibition l-NAME (1mM). Exogenously added NO (spermine-NONO-ate) stimulated Na/K-ATPase (EC50=3.8 ?M; n=6/grp), via decrease in Km, in PLM(WT) but not PLM(KO) or PLM(3SA) myocytes (where phospholemman cannot be phosphorylated) as measured by whole-cell perforated-patch clamp. Field-stimulation with l-NAME or PKC-inhibitor (2 ?M Bis) resulted in elevated intracellular Na(+) (22 ± 1.5 and 24 ± 2 respectively, vs. 14 ± 0.6mM in controls) in SBFI-AM-loaded rat myocytes. Arrhythmia incidence was significantly increased in rat hearts paced in the presence of l-NAME (and this was reversed by l-arginine), as well as in PLM(3SA) mouse hearts but not PLM(WT) and PLM(KO). We provide physiological and biochemical evidence for a novel regulatory pathway whereby NO activates Na/K-ATPase via phospholemman phosphorylation and thereby limits Na(+) and Ca(2+) overload and arrhythmias. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes". PMID:23612119

Pavlovic, Davor; Hall, Andrew R; Kennington, Erika J; Aughton, Karen; Boguslavskyi, Andrii; Fuller, William; Despa, Sanda; Bers, Donald M; Shattock, Michael J

2013-08-01

353

Ionization induced relaxation in solvation structure: A comparison between Na(H2O)n and Na(NH3)n  

NASA Astrophysics Data System (ADS)

The constant ionization potential for hydrated sodium clusters Na(H2O)n just beyond n =4, as observed in photoionization experiments, has long been a puzzle in violation of the well-known (n+1)-1/3 rule that governs the gradual transition in properties from clusters to the bulk. Based on first principles calculations, a link is identified between this puzzle and an important process in solution: the reorganization of the solvation structure after the removal of a charged particle. Na(H2O)n is a prototypical system with a solvated electron coexisting with a solvated sodium ion, and the cluster structure is determined by a balance among three factors: solute-solvent (Na+-H2O), solvent-solvent (H2O-H2O), and electron-solvent (OH{e}HO) interactions. Upon the removal of an electron by photoionization, extensive structural reorganization is induced to reorient OH{e }HO features in the neutral Na(H2O )n for better Na+-H2O and H2O-H2O interactions in the cationic Na+(H2O)n. The large amount of energy released, often reaching 1eV or more, indicates that experimentally measured ion signals actually come from autoionization via vertical excitation to high Rydberg states below the vertical ionization potential, which induces extensive structural reorganization and the loss of a few solvent molecules. It provides a coherent explanation for all the peculiar features in the ionization experiments, not only for Na(H2O)n but also for Li(H2O)n and Cs(H2O)n. In addition, the contrast between Na(H2O)n and Na(NH3)n experiments is accounted for by the much smaller relaxation energy for Na(NH3)n, for which the structures and energetics are also elucidated.

Gao, Bing; Liu, Zhi-Feng

2007-02-01

354

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

2014-12-12

355

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 10-4 S cm-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 75Na2S·25P2S5 (mol%). The glass-ceramic electrolyte prepared by milling for 1.5 h and consecutive heat treatment at 270 °C for 1 h showed the highest conductivity of 4.6 × 10-4 S cm-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 60 mAh per gram of NaCrO2 for 15 cycles.

Hayashi, Akitoshi; Noi, Kousuke; Tanibata, Naoto; Nagao, Motohiro; Tatsumisago, Masahiro

2014-07-01

356

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

357

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

358

Lymphocytic Na(+)-H+ exchange increases after an oral glucose challenge.  

PubMed

The effects of oral glucose challenge on plasma glucose concentration, plasma insulin concentration, arterial blood pressure, cytosolic pH (pHi), cytosolic free Na+ concentration ([Na+]i), and cellular Na(+)-H+ exchange activity were investigated in 16 healthy subjects. The pHi, [Na+]i, and Na(+)-H+ exchange activity were measured in intact lymphocytes by using the fluorescent dye technique. The oral glucose challenge significantly increased plasma glucose, plasma insulin, and the lymphocytic Na(+)-H+ exchange activity, measured as change of pHi per second (control [0 hours], 5.20 +/- 0.53 x 10(-3) dpHi/s; 1 hour after glucose administration, 8.28 +/- 1.07 x 10(-3) dpHi/s; 2 hours after glucose administration, 8.15 +/- 1.18 x 10(-3) dpHi/s; P = .002). The lymphocytic Na(+)-H+ exchange was significantly correlated with plasma glucose concentration (r = .357, P = .041). During steady state euglycemic hyperinsulinemic clamp, the Na(+)-H+ exchange activity was not significantly changed compared with baseline values. The study shows that changes of blood glucose levels can induce an acute increase in Na(+)-H+ exchange activity. Systolic blood pressure and Na(+)-H+ exchange activity were significantly (P < .001) but weakly correlated during an oral glucose challenge. PMID:7554137

Tepel, M; Schlotmann, R; Barenbrock, M; Kisters, K; Klaus, T; Spieker, C; Walter, M; Meyer, C; Bretzel, R G; Zidek, W

1995-11-01

359

Cholinergic stimulation of the Na+/K+ adenosine triphosphatase as revealed by microphysiometry.  

PubMed Central

The activation of a wide range of cellular receptors has been detected previously using a novel instrument, the microphysiometer. In this study microphysiometry was used to monitor the basal and cholinergic-stimulated activity of the Na+/K+ adenosine triphosphatase (ATPase) (the Na+/K+ pump) in the human rhabdomyosarcoma cell line TE671. Manipulations of Na+/K+ ATPase activity with ouabain or removal of extracellular K+ revealed that this ion pump was responsible for 8.8 +/- 0.7% of the total cellular energy utilization by those cells as monitored by the production of acid metabolites. Activation of the pump after a period of inhibition transiently increased the acidification rate above baseline, corresponding to increases in intracellular [Na+] ([Na+]i) occurring while the pump was off. The amplitude of this transient was a function of the total [Na+]i excursion in the absence of pump activity, which in turn depended on the duration of pump inhibition and the Na+ influx rate. Manipulations of the mode of energy metabolism in these cells by changes of the carbon substrate and use of metabolic inhibitors revealed that, unlike some other cells studied, the Na+/K+ ATPase in TE671 cells does not depend on any one mode of metabolism for its adenosine triphosphate source. Stimulation of cholinergic receptors in these cells with carbachol activated the Na+/K+ ATPase via an increase in [Na+]i rather than a direct activation of the ATPase. PMID:8386019

Miller, D L; Olson, J C; Parce, J W; Owicki, J C

1993-01-01

360

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

361

Regulation of rat intestinal Na-dependent phosphate transporters by dietary phosphate  

PubMed Central

Hyperphosphatemia associated with chronic kidney disease is one of the factors that can promote vascular calcification, and intestinal Pi absorption is one of the pharmacological targets that prevents it. The type II Na-Pi cotransporter NaPi-2b is the major transporter that mediates Pi reabsorption in the intestine. The potential role and regulation of other Na-Pi transporters remain unknown. We have identified expression of the type III Na-Pi cotransporter PiT-1 in the apical membrane of enterocytes. Na-Pi transport activity and NaPi-2b and PiT-1 proteins are mostly expressed in the duodenum and jejunum of rat small intestine; their expression is negligible in the ileum. In response to a chronic low-Pi diet, there is an adaptive response restricted to the jejunum, with increased brush border membrane (BBM) Na-Pi transport activity and NaPi-2b, but not PiT-1, protein and mRNA abundance. However, in rats acutely switched from a low- to a high-Pi diet, there is an increase in BBM Na-Pi transport activity in the duodenum that is associated with an increase in BBM NaPi-2b protein abundance. Acute adaptive upregulation is restricted to the duodenum and induces an increase in serum Pi that produces a transient postprandial hyperphosphatemia. Our study, therefore, indicates that Na-Pi transport activity and NaPi-2b protein expression are differentially regulated in the duodenum vs. the jejunum and that postprandial upregulation of NaPi-2b could be a potential target for treatment of hyperphosphatemia. PMID:19675183

Caldas, Yupanqui; Sutherland, Eileen; Wilson, Paul; Breusegem, Sophia; Barry, Nicholas; Blaine, Judith; Jiang, Tao; Wang, Xiaoxin X.; Levi, Moshe

2009-01-01

362

Na 2O solubility in CaO-MgO-SiO 2 melts  

NASA Astrophysics Data System (ADS)

The sodium solubility in silicate melts in the CaO-MgO-SiO 2 (CMS) system at 1400 °C has been measured by using a closed thermochemical reactor designed to control alkali metal activity. In this reactor, Na (g) evaporation from a Na 2O- xSiO 2 melt imposes an alkali metal vapor pressure in equilibrium with the molten silicate samples. Because of equilibrium conditions in the reactor, the activity of sodium-metal oxide in the molten samples is the same as that of the source, i.e., aNa 2O (sample) = aNa 2O (source). This design also allows to determine the sodium oxide activity coefficient in the samples. Thirty-three different CMS compositions were studied. The results show that the amount of sodium entering from the gas phase (i.e., Na 2O solubility) is strongly sensitive to silica content of the melt and, to a lesser extent, the relative amounts of CaO and MgO. Despite the large range of tested melt compositions (0 < CaO and MgO < 40; 40 < SiO 2 < 100; in wt%), we found that Na 2O solubility is conveniently modeled as a linear function of the optical basicity ( ?) calculated on a Na-free basis melt composition. In our experiments, ?Na 2O (sample) ranges from 7 × 10 -7 to 5 × 10 -6, indicating a strongly non-ideal behavior of Na 2O solubility in the studied CMS melts (?Na 2O (sample) ? 1). In addition to showing the effect of sodium on phase relationships in the CMS system, this Na 2O solubility study brings valuable new constraints on how melt structure controls the solubility of Na in the CMS silicate melts. Our results suggest that Na 2O addition causes depolymerization of the melt by preferential breaking of Si-O-Si bonds of the most polymerized tetrahedral sites, mainly Q 4.

Mathieu, R.; Libourel, G.; Deloule, E.; Tissandier, L.; Rapin, C.; Podor, R.

2011-01-01

363

Covering surface nanobubbles with a NaCl nanoblanket.  

PubMed

By letting a NaCl aqueous solution of low (0.01 M) concentration evaporate on a highly oriented pyrolytic graphite (HOPG) surface, it is possible to form a thin film of salt. However, pre-existing surface nanobubbles prevent the homogeneous coverage of the surface with the salt, keeping the footprint areas on the substrate pristine. Comparing the surface nanobubbles in the salt solution with their associated footprint after drying, provides information on the shrinkage of nanobubbles during the hours-long process of drying the liquid film. At a slightly higher NaCl concentration and thus salt layer thickness, the nanobubbles are covered with a thin blanket of salt. Once the liquid film has evaporated until a water film remains that is smaller than the height of the nanobubbles, the blanket of salt cracks and unfolds into a flower-like pattern of salt flakes that is located at the rim of the nanobubble footprint. The formation of a blanket of salt covering the nanobubbles is likely to considerably or even completely block the gas out-flux from the nanobubble, partially stabilizing the nanobubbles against dissolution. PMID:23937683

Berkelaar, Robin P; Zandvliet, Harold J W; Lohse, Detlef

2013-09-10

364

Dielectronic recombination resonances in Na{sup 8+}  

SciTech Connect

The electron-ion recombination spectrum of the Li-like Na{sup 8+} ion in the energy range 0.0-0.5 eV is presented. Experimental results obtained by storage-ring techniques are compared with a calculated spectrum, based on a combination of relativistic many-body methods and complex rotation, and the agreement is found to be very good. The deviations between measured and calculated dielectronic recombination resonance energies are usually below about 2 meV with a maximum difference at 5.5 meV, while the theoretical cross sections deviate by at most 20% from the experiment. The recombination spectrum in the investigated energy region is determined by the 2p{sub j}7l{sub j{sup '}} Rydberg manifold of dielectronic recombination resonances, comprising 61 states within half an eV above the ground state of Na{sup 8+}. The theoretical resonance parameters of all contributing states are provided.

Nikolic, D.; Lindroth, E.; Kieslich, S.; Brandau, C.; Schippers, S.; Shi, W.; Mueller, A.; Gwinner, G.; Schnell, M.; Wolf, A. [Atomic Physics, Fysikum, Stockholm University, S-106 91 Stockholm (Sweden); Institut fuer Kernphysik, Justus-Liebig-Universitaet Giessen, D-35392 Giessen (Germany); Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany)

2004-12-01

365

Will Lanthanum Halide Scintillators Make NaI(Tl) Obsolete?  

NASA Astrophysics Data System (ADS)

The commercial availability of lanthanum halide scintillators (LaCl3:Ce and LaBr3:Ce) has been much anticipated due to their significantly better resolution (3-4% at 662 keV) relative to NaI(Tl). Unfortunately, our initial investigation of these scintillators revealed significant alpha contamination quite apparent in background spectra. Using measurements of the detector in coincidence with a HPGe detector, we identified the alpha-contaminant as Ac-227. Since this time, the alpha contamination has been substantially reduced so that a second contaminant, La-138 (a beta, gamma, and x-ray source) has become the dominant contaminant in the material. Commercially-available sizes of lanthanum halide scintillators have now reached sizes suitable for handheld Radioactive Isotope Identification Devices (RIIDs). To study the potential of this new material for RIIDs we performed a series of measurements comparing a 1.5'' x 1.5'' LaBr3 detector with an Exploranium GR-135 RIID, which contains a 1.5'' x 2.2'' NaI(Tl) detector. Measurements were taken for short timeframes of seconds to minutes, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM) typically found in cargo. Of particular interest was the extent to which interference between the La-138 contaminant and K-40, a radioisotope commonly found in NORM, compromise the lanthanum halide performance. Example spectra, detector comparisons and results will be shown.

Milbrath, Brian

2006-05-01

366

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

367

Lyotropic anions. Na channel gating and Ca electrode response  

PubMed Central

The effects of external anions on gating of Na channels of frog skeletal muscle were studied under voltage clamp. Anions reversibly shift the voltage dependence of peak sodium permeability and of steady state sodium inactivation towards more negative potentials in the sequence: methanesulfonate less than or equal to Cl- less than or equal to acetate less than Br- less than or equal to NO-3 less than or equal to SO2-4 less than benzenesulfonate less than SCN- less than ClO-4; approximately the lyotropic sequence. Voltage shifts are graded with mole fraction in mixtures and are roughly additive to calcium shifts. The peak PNa is not greatly affected. Except for SO2-4, these anions did not change the Ca++ activity of the solutions as measured with the dye murexide. Shifts of gating can be explained as the electrostatic effect of anion adsorption to the Na channel or to nearby lipid. Such adsorption is expected to follow the lyotropic series. Anions also interfere significantly with the response of a Ca-sensitive membrane electrode following the same sequence of effectiveness as the shifts of gating. The lyotropic anions decrease the Ca++ sensitivity and cause anomalously negative responses of the Ca electrode because these anions are somewhat permeant in the hydrophobic detector membrane. PMID:6302198

1983-01-01

368

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 Mössbauer 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 Mössbauer spectrum is a broad quadrupole doublet with chemical shift, ? ? 0.33 mm/s and quadrupole splitting, ?Eq ? 0.68 mm/s. Variable temperature 57Fe Mössbauer 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

369

Results on correlations and fluctuations from NA49  

E-print Network

The large acceptance and high momentum resolution as well as the significant particle identification capabilities of the NA49 experiment at the CERN SPS allow for a broad study of fluctuations and correlations in hadronic interactions. In the first part recent results on event-by-event charge and p_t fluctuations are presented. Charge fluctuations in central Pb+Pb reactions are investigated at three different beam energies (40, 80, and 158 AGeV), while for the p_t fluctuations the focus is put on the system size dependence at 158 AGeV. In the second part recent results on Bose Einstein correlations of h-h- pairs in minimum bias Pb+Pb reactions at 40 and 158 AGeV, as well as of K+K+ and K-K- pairs in central Pb+Pb collisions at 158 AGeV are shown. Additionally, other types of two particle correlations, namely pi p, Lambda p, and Lambda Lambda correlations, have been measured by the NA49 experiment. Finally, results on the energy and system size dependence of deuteron coalescence are discussed.

C. Blume

2002-09-20

370

Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current  

PubMed Central

Evolutionary origin and physiological significance of the tetrodotoxin (TTX) resistance of the vertebrate cardiac Na+ current (INa) is still unresolved. To this end, TTX sensitivity of the cardiac INa was examined in cardiac myocytes of a cyclostome (lamprey), three teleost fishes (crucian carp, burbot and rainbow trout), a clawed frog, a snake (viper) and a bird (quail). In lamprey, teleost fishes, frog and bird the cardiac INa was highly TTX-sensitive with EC50-values between 1.4 and 6.6 nmol·L?1. In the snake heart, about 80% of the INa was TTX-resistant with EC50 value of 0.65 ?mol·L?1, the rest being TTX-sensitive (EC50 = 0.5 nmol·L?1). Although TTX-resistance of the cardiac INa appears to be limited to mammals and reptiles, the presence of TTX-resistant isoform of Na+ channel in the lamprey heart suggest an early evolutionary origin of the TTX-resistance, perhaps in the common ancestor of all vertebrates. PMID:22163193

Vornanen, Matti; Hassinen, Minna; Haverinen, Jaakko

2011-01-01

371

1 nA Beam Position Monitoring System  

NASA Astrophysics Data System (ADS)

A system has been developed at Jefferson Lab for measuring transverse position of very low current beams delivered to the Experimental Hall B of the Continuous Electron Beam Accelerator Facility (CEBAF). At the heart of the system is a position sensitive cavity operating at 1497 MHz. The cavity utilizes a unique design which achieves a high sensitivity to beam position at a relatively low cavity Q. The cavity output RF signal is processed using a down-converter and a commercial lock-in amplifier operating at 100 kHz. The system interfaces with a VME based EPICS contol system using the IEEE 488 bus. The main features of the system are simple and robust design, and wide dynamic range capable of handling beam currents from 1 nA to 1000 nA with an expected resolution better than 100 ?m. This paper outlines the design and presents first operational experience with the system.

Ursic, R.; Piller, M.

1997-05-01

372

Observando Las Fases Y Características De La Luna  

NSDL National Science Digital Library

Learners will first observe a first quarter Moon and as a group, predict which phase the Moon will be in during the next observation. They then continue to chart the progress of the lunar cycle of phases throughout the following weeks to better understand the sequence. This is Actividad 1.2 as part of El Universo a Sus Pies, a Spanish-language curriculum, available for purchase.

2013-04-22

373

Fases de la luna (Alternate title: Lunar phases)  

NSDL National Science Digital Library

What causes the phases of the moon? This informational piece, part of an interactive laboratory series for grades 8-12, introduces students to three interactive lab activities about moon phases. In the first activity, students virtually view the moon from a fixed location in space to determine which half of the moon is lighted by the sun as it moves through its phases. In the second activity, students choose the shading of the moon as it would appear from the Earth. Nine questions with printable results are provided. The third activity simulates the moon revolving around the Earth. As the moon revolves, a window shows the view of the moon from Earth. Students control the speed of the simulation and can jump to any phase of the moon. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

374

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

375

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; Flügge, Ulf-Ingo; Heldt, Hans W.; Kanai, Ryuzi

1990-01-01

376

FXYD Proteins: New Tissue-Specific Regulators of the Ubiquitous Na,K-ATPase  

NSDL National Science Digital Library

The Na,K-ATPase is a plasma membrane enzyme that is responsible for maintaining the Na+ and K+ gradients between the intra- and extracellular milieu of animal cells. It consists of a catalytic α subunit and a regulatory β subunit. Na,K-ATPase transports Na+ out of the cell and K+ into the cell against their respective chemical gradients by using energy derived from the hydrolysis of ATP. Maintenance of the Na+ and K+ gradients by the Na,K-ATPase is essential for basic cellular homeostasis as well as for specialized functions of various tissues. Rigorous control of the Na+ and K+ gradients by Na,K-ATPase is necessary for preservation of cell volume, maintenance of membrane potential, and activity of secondary transporters that provide the cell with nutrients or regulate cellular solute concentrations. Moreover, in renal epithelial cells, the Na,K-ATPase, exclusively located in the basolateral membrane, is the driving force for the Na+ reabsorption that maintains extracellular volume and, hence, blood pressure. In addition, in heart and skeletal muscle, the activity of Na,K-ATPase is tightly coupled to the activity of a Na+/Ca2+-exchanger that controls muscle contraction. Finally, in the nervous system, Na,K-ATPase contributes to the re-establishment of the basal Na+ and K+ gradients both during action potentials and consequent to neuronal excitation. The Na,K-ATPase must be finely regulated to fulfil its important tasks under changing physiological conditions. Tissue-specific differences in Na,K-ATPase activity are achieved by the expression of four α and three β isoforms, which potentially can form 12 Na,K-ATPase isozymes with different functional properties. Moreover, various hormones and neurotransmitters are involved in the short- and long-term control of Na,K-ATPase; they regulate its activity and/or expression through protein kinase phosphorylation or transcriptional control. In this review, we discuss a novel regulatory mechanism of Na,K-ATPase that is mediated by the interaction of Na,K-ATPase with small membrane proteins of the FXYD family that so far have been considered as channels or regulators of ion channels. The FXYD proteins FXYD1 through FXYD7 exhibit tissue-specific distribution. FXYD1 (phospholemman) in heart and skeletal muscle, FXYD2 (the γ subunit of Na,K-ATPase) and FXYD4 [corticosteroid hormone-induced factor (CHIF)] in the kidney, and FXYD7 in the brain associate preferentially with the Na,K-ATPase α1-β1 isozyme and modulate its transport properties in a way that conforms to tissue-specific requirements. Thus, FXYD proteins contribute to proper handling of Na+ and K+ by the most widely expressed Na,K-ATPase α1-β1 isozymes, and ensure correct function in such mechanisms as renal Na+ reabsorption, muscle contraction, and neuronal excitability

Gilles Crambert (University of Lausanne;Institute of Pharmacology and Toxicology REV); Kathi Geering (University of Lausanne;Institute of Pharmacology and Toxicology REV)

2003-01-21

377

SLC4A11 is an EIPA-sensitive Na(+) permeable pHi regulator.  

PubMed

Slc4a11, a member of the solute linked cotransporter 4 family that is comprised predominantly of bicarbonate transporters, was described as an electrogenic 2Na(+)-B(OH)4(-) (borate) cotransporter and a Na(+)-2OH(-) cotransporter. The goal of the current study was to confirm and/or clarify the function of SLC4A11. In HEK293 cells transfected with SLC4A11 we tested if SLC4A11 is a: 1) Na(+)-HCO3(-) cotransporter, 2) Na(+)-OH(-)(H(+)) transporter, and/or 3) Na(+)-B(OH)4(-) cotransporter. CO2/HCO3(-) perfusion yielded no significant differences in rate or extent of pHi changes or Na(+) flux in SLC4A11-transfected compared with control cells. Similarly, in CO2/HCO3(-), acidification on removal of Na(+) and alkalinization on Na(+) add back were not significantly different between control and transfected indicating that SLC4A11 does not have Na(+)-HCO3(-) cotransport activity. In the absence of CO2/HCO3(-), SLC4A11-transfected cells showed higher resting intracelllular Na(+) concentration ([Na(+)]i; 25 vs. 17 mM), increased NH4(+)-induced acidification and increased acid recovery rate (160%) after an NH4 pulse. Na(+) efflux and influx were faster (80%) following Na(+) removal and add back, respectively, indicative of Na(+)-OH(-)(H(+)) transport by SLC4A11. The increased alkalinization recovery was confirmed in NHE-deficient PS120 cells demonstrating that SLC4A11 is a bonafide Na(+)-OH(-)(H(+)) transporter and not an activator of NHEs. SLC4A11-mediated H(+) efflux is inhibited by 5-(N-ethyl-N-isopropyl) amiloride (EIPA; EC50: 0.1 ?M). The presence of 10 mM borate did not alter dpHi/dt or ?pH during a Na(+)-free pulse in SLC4A11-transfected cells. In summary our results show that SLC4A11 is not a bicarbonate or borate-linked transporter but has significant EIPA-sensitive Na(+)-OH(-)(H(+)) and NH4(+) permeability. PMID:23864606

Ogando, Diego G; Jalimarada, Supriya S; Zhang, Wenlin; Vithana, Eranga N; Bonanno, Joseph A

2013-10-01

378

SLC4A11 is an EIPA-sensitive Na+ permeable pHi regulator  

PubMed Central

Slc4a11, a member of the solute linked cotransporter 4 family that is comprised predominantly of bicarbonate transporters, was described as an electrogenic 2Na+-B(OH)4? (borate) cotransporter and a Na+-2OH? cotransporter. The goal of the current study was to confirm and/or clarify the function of SLC4A11. In HEK293 cells transfected with SLC4A11 we tested if SLC4A11 is a: 1) Na+-HCO3? cotransporter, 2) Na+-OH?(H+) transporter, and/or 3) Na+-B(OH)4? cotransporter. CO2/HCO3? perfusion yielded no significant differences in rate or extent of pHi changes or Na+ flux in SLC4A11-transfected compared with control cells. Similarly, in CO2/HCO3?, acidification on removal of Na+ and alkalinization on Na+ add back were not significantly different between control and transfected indicating that SLC4A11 does not have Na+-HCO3? cotransport activity. In the absence of CO2/HCO3?, SLC4A11-transfected cells showed higher resting intracelllular Na+ concentration ([Na+]i; 25 vs. 17 mM), increased NH4+-induced acidification and increased acid recovery rate (160%) after an NH4 pulse. Na+ efflux and influx were faster (80%) following Na+ removal and add back, respectively, indicative of Na+-OH?(H+) transport by SLC4A11. The increased alkalinization recovery was confirmed in NHE-deficient PS120 cells demonstrating that SLC4A11 is a bonafide Na+-OH?(H+) transporter and not an activator of NHEs. SLC4A11-mediated H+ efflux is inhibited by 5-(N-ethyl-N-isopropyl) amiloride (EIPA; EC50: 0.1 ?M). The presence of 10 mM borate did not alter dpHi/dt or ?pH during a Na+-free pulse in SLC4A11-transfected cells. In summary our results show that SLC4A11 is not a bicarbonate or borate-linked transporter but has significant EIPA-sensitive Na+-OH?(H+) and NH4+ permeability. PMID:23864606

Ogando, Diego G.; Jalimarada, Supriya S.; Zhang, Wenlin; Vithana, Eranga N.

2013-01-01

379

Growth responses and ion accumulation in the halophytic legume Prosopis strombulifera are determined by Na2 SO4 and NaCl.  

PubMed

Halophytes are potential gene sources for genetic manipulation of economically important crop species. This study addresses the physiological responses of a widespread halophyte, Prosopis strombulifera (Lam.) Benth to salinity. We hypothesised that increasing concentrations of the two major salts present in soils of central Argentina (Na2 SO4 , NaCl, or their iso-osmotic mixture) would produce distinct physiological responses. We used hydroponically grown P. strombulifera to test this hypothesis, analysing growth parameters, water relations, photosynthetic pigments, cations and anions. These plants showed a halophytic response to NaCl, but strong general inhibition of growth in response to iso-osmotic solutions containing Na2 SO4 . The explanation for the adaptive success of P. strombulifera in high NaCl conditions seems to be related to a delicate balance between Na(+) accumulation (and its use for osmotic adjustment) and efficient compartmentalisation in vacuoles, the ability of the whole plant to ensure sufficient K(+) supply by maintaining high K(+) /Na(+) discrimination, and maintenance of normal Ca(2+) levels in leaves. The three salt treatments had different effects on the accumulation of ions. Findings in bi-saline-treated plants were of particular interest, where most of the physiological parameters studied showed partial alleviation of SO4 (2-) -induced toxicity by Cl(-) . Thus, discussions on physiological responses to salinity could be further expanded in a way that more closely mimics natural salt environments. PMID:23869994

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

2013-07-22

380

Early transcriptomic adaptation to Na?CO? stress altered the expression of a quarter of the total genes in the maize genome and exhibited shared and distinctive profiles with NaCl and high pH stresses.  

PubMed

Sodium carbonate (Na?CO?) presents a huge challenge to plants by the combined damaging effects of Na?, high pH, and CO?²?. Little is known about the cellular responses to Na?CO? stress. In this study, the transcriptome of maize (Zea mays L. cv. B73) roots exposed to Na?CO? stress for 5?h was compared with those of NaCl and NaOH stresses. The expression of 8,319 genes, representing over a quarter of the total number of genes in the maize genome, was altered by Na?CO? stress, and the downregulated genes (5,232) outnumbered the upregulated genes (3,087). The effects of Na?CO? differed from those of NaCl and NaOH, primarily by downregulating different categories of genes. Pathways commonly altered by Na?CO?, NaCl, and NaOH were enriched in phenylpropanoid biosynthesis, oxidation of unsaturated fatty acids, ATP-binding cassette (ABC) transporters, as well as the metabolism of secondary metabolites. Genes for brassinosteroid biosynthesis were specifically upregulated by Na?CO?, while genes involved in ascorbate and aldarate metabolism, protein processing in the endoplasmic reticulum and by N-glycosylation, fatty acid biosynthesis, and the circadian rhythm were downregulated. This work provides the first holistic picture of early transcriptomic adaptation to Na?CO? stress, and highlights potential molecular pathways that could be manipulated to improve tolerance in maize. PMID:24034274

Zhang, Li-Min; Liu, Xiang-Guo; Qu, Xin-Ning; Yu, Ying; Han, Si-Ping; Dou, Yao; Xu, Yao-Yao; Jing, Hai-Chun; Hao, Dong-Yun

2013-11-01

381

Theoretical Study of Na3-C60 and Na4-C60 Clusters: Pathways to Nanoscale Contacts  

NASA Astrophysics Data System (ADS)

We continue our interest in fullerene-alkali complexes^1-2 by investigating the physical and chemical properties of Na3-C60 and Na4-C60 systems. Five categories of adsorption sites for the alkali atoms on the fullerene molecule, namely fivefold, threefold, midbond-long, midbond-short and top, are considered. Electron correlation effects, using both Many Body Perturbation Theory (MBPT) and Density Functional Theories (DFT) are incorporated in the calculations for binding energies and optimal intermolecular bondlengths. For these complexes, various properties including bondlengths, ground-state energies, optimum absorbate distances, dissociation channels, and dissociation energies are presented. Possibility of tunneling between different sites is investigated. We also examine implications for the fabrication of nanoscale contacts, and for the study of dynamical systems involving C60. *A. S. Hira and A. K. Ray, Phys. Rev. A 52, 141(1995); A 54, 2205(1996). *A. S. Hira, Billy Terrazas, Erica Velarde and Desirae Vigil, ``An Ab Initio Theoretical Study of Alkali-C60 and Alkali-(C60)n Clusters,'' Bull. Am. Phys. Soc. 49, 599 (March 2004).

Bulnes, Daniel

2005-03-01

382

The current fluctuations and accumulated pitting damage of mild steel in NaNO 2-NaCl solution  

NASA Astrophysics Data System (ADS)

Metastable pitting behavior of mild steel in 0.1 M NaNO 2 + 0.05 M NaCl solution at constant potentials was studied. The current fluctuations showed the feature of quick rise and relatively slow decay, indicating quick breakdown and slow repassivation of the passive film on the surface. The current fluctuations resulted in observable pits on sample surface. A bigger pit may be composed of several small pits, which suggests that a repassivated metastable pit may still be active site for following metastable pits to nucleate. Repeated local dissolution events around a certain active site caused accumulated corrosion damage. The pit size distribution calculated from the current fluctuations was very close to that observed with SEM, indicating that there is good correlation between current fluctuations and the growth process of metastable pits. Corrosion products may pile up at pit mouth and lead the pit to an occluded state, thus metastable pitting process was replaced by stable pitting. Once the pit mouth was completely blocked up by corrosion products, the pit would stop growing.

Tang, Yuming; Zuo, Yu; Zhao, Hao

2005-04-01

383

Wigner crystallization in Na3Cu2O4 and Na8Cu5O10 chain compounds.  

NASA Astrophysics Data System (ADS)

We report the synthesis of novel doped edge-sharing chain compounds Na3Cu2O4 and Na8Cu5O10, which form insulating states with commensurate charge order [1]. We identify these systems as one-dimensional Wigner lattices, where the charge order is determined by the long-range Coulomb interaction and the number of holes in the d-shell of Cu. Our interpretation is supported by X-ray structure data as well as by an analysis of magnetic susceptibility and specific heat data. Remarkably, due to large second neighbor Cu-Cu hopping, these systems allow for an unambiguous distinction between the classical Wigner lattice and the 4kF charge-density wave of quantum mechanical origin. Finally, we briefly discuss the domain-wall type charge excitations and the theoretical expectation for the optical conductivity of 1D Wigner lattices [2]. [1] P. Horsch, M. Sofin, M. Mayr, and M. Jansen, Phys. Rev. Lett. 94, 076403 (2005). [2] M. Mayr and P. Horsch, (unpublished).

Horsch, P.; Sofin, M.; Mayr, M.; Jansen, M.

2006-03-01

384

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

PubMed

A two-step K(+)-Na+ and Ag(+)-Na+ ion-exchange technique is introduced to fabricate single-mode channel waveguides in BK7 glass for the telecom-wavelength region. The dependencies of insertion loss, polarization-dependent loss (PDL), end bending loss of curved waveguides on channel width, diffusion time, and annealing time are investigated. Results show that postannealing is a required process for improving waveguide properties and an optimal annealing time exists. Although relatively narrow mask openings are used in most one-step ion-exchange processes, a wider channel width, to as wide as 10 microm, is preferred for this two-step method. The minimum coupling loss to/from single-mode fiber and the propagation loss is found to be 0.4 dB and 0.3 dB/cm, respectively. For 5-cm-long waveguides the PDL is less than 0.1 dB. For the S-bend structure the cosine curve exhibit apparently a lower bending loss than the double-arc curve. PMID:12510929

Zou, Jizuo; Zhao, Feng; Chen, Ray T

2002-12-20

385

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

NASA Astrophysics Data System (ADS)

A two-step K+-Na+ and Ag+-Na+ ion-exchange technique is introduced to fabricate single-mode channel waveguides in BK7 glass for the telecom-wavelength region. The dependencies of insertion loss, polarization-dependent loss (PDL), and bending loss of curved waveguides on channel width, diffusion time, and annealing time are investigated. Results show that postannealing is a required process for improving waveguide properties and an optimal annealing time exists. Although relatively narrow mask openings are used in most one-step ion-exchange processes, a wider channel width, to as wide as 10 mum, is preferred for this two-step method. The minimum coupling loss to/from single-mode fiber and the propagation loss is found to be 0.4 dB and 0.3 dB/cm, respectively. For 5-cm-long waveguides the PDL is less than 0.1 dB. For the S-bend structure the cosine curve exhibits apparently a lower bending loss than the double-arc curve.

Zou, Jizuo; Zhao, Feng; Chen, Ray T.

2002-12-01

386

Na(+) transport in glycophytic plants: what we know and would like to know.  

PubMed

Soil salinity decreases the growth rate of plants and can severely limit the productivity of crop plants. The ability to tolerate salinity stress differs widely between species of plants as well as within species. As an important component of salinity tolerance, a better understanding of the mechanisms of Na(+) transport will assist in the development of plants with improved salinity tolerance and, importantly, might lead to increased yields from crop plants growing in challenging environments. This review summarizes the current understanding of the components of Na(+) transport in glycophytic plants, including those at the soil to root interface, transport of Na(+) to the xylem, control of Na(+) loading in the stele and partitioning of the accumulated Na(+) within the shoot and individual cells. Using this knowledge, strategies to modify Na(+) transport and engineer plant salinity tolerance, as well as areas of research which merit particular attention in order to further improve the understanding of salinity tolerance in plants, are discussed. PMID:19968828

Craig Plett, Darren; Møller, Inge Skrumsager

2010-04-01

387

First-principles study of the interaction of hydrogen molecular on Na-adsorbed graphene  

NASA Astrophysics Data System (ADS)

We have performed density functional theory-based first-principles calculations to study the stability, geometrical structures, and electronic/magnetic properties of pure graphene, sodium (Na)-adsorbed graphene and also the adsorption properties of H_2 -molecular ranging from one to five molecules on their preferred structures. Using the information of binding energy of Na at different adsorption sites of varying sized graphene supercell, it has been observed that hollow position is the most preferred site for Na adsorption, and the same in 3 × 3 supercell has been used for further calculations. The band structure and density of states calculations have been performed to study the electronic/magnetic properties of Na-atom graphene. On comparing adsorption energy per H_2 -molecular in pure and Na-adsorbed graphene, we find that presence of Na atom, in general, enhances binding strength to H_2 -moleculars.

Pantha, Nurapati; Belbase, Kamal; Adhikari, Narayan Prasad

2014-07-01

388

The role of NaYF4 nanoparticles in inverted polymer solar cells  

NASA Astrophysics Data System (ADS)

NaYF4 nanoparticles are doped into PCDTBT:PCBM blend as a dual function additive to improve light absorption of inverted polymer solar cells. The dependence of device performance on NaYF4 in the blend film is investigated. The results show that the short-circuit current density is apparently enhanced by doping NaYF4 into the active layer while maintaining the open-circuit voltage and fill factor, leading to an increase in power conversion efficiency. NaYF4 maybe play two kinds of role for light absorption enhancement. Up-conversion (UC) emission from Y3+ is observed. The scattering effect of NaYF4 nanoparticles (NPs) enhances the light absorption in visible region. The performance of polymer solar cell doped with NaYF4 is compared with that of undoped. The concept of integrating nanoparticles into active layer suggests a promising and practical pathway for improving absorption of polymer solar cells.

Guo, Wenbin; Jiang, Huimin; Liu, Chunyu; He, Yeyuan; Zhang, Xinyuan

2014-07-01

389

Cu2Sb thin films as anode for Na-ion batteries  

SciTech Connect

Cu2Sb thin films prepared by magnetron sputtering are evaluated as an anode material for Na-ion batteries. The starting material is composed of nanocrystallites with the desired tetragonal P4/nmm structure. The study of the reaction mechanism reveals the formation of an amorphous/nanocrystalline phase of composition close to Na3Sb as the final reaction product. The solid electrolyte interphase (SEI) material is mostly composed of carbonates (Na2CO3, NaCO3R). The Cu2Sb anode possesses moderate capacity retention with a reversible storage capacity (250 mAh/g) close to the theoretical value (323 mAh/g), an average reaction potential of around 0.55 V vs. Na/Na+, and a high rate performance (10 C-rate).

Baggetto, Loic [ORNL] [ORNL; Allcorn, Eric [University of Texas at Austin] [University of Texas at Austin; Manthiram, Arumugam [University of Texas at Austin] [University of Texas at Austin; Veith, Gabriel M [ORNL] [ORNL

2013-01-01

390

Visible laser induced positive ion emissions from NaCl nanoparticles prepared by droplet rapid drying  

NASA Astrophysics Data System (ADS)

A novel convenient way for the formation of sodium chloride (NaCl) nanoparticles on silicon wafer is proposed by using a droplet rapid drying method. The laser induced positive ion emissions from NaCl nanoparticles with and without water treatment is demonstrated by using a laser desorption/ionization time-of-flight mass spectrometer, with laser intensity well below the plasma formation threshold. It is found that the positive ion emissions from NaCl nanoparticles are obviously higher than that from microsize NaCl particles under soft 532 nm laser irradiations, and water adsorption can efficiently enhance the ion emissions from NaCl nanoparticles. The initial kinetic energies of the emitted ions are estimated as 16-17 eV. The synergy of the ultra-thermal effect in nanomaterials, the defect-mediated multiphoton processes, and the existence of intermediate states in NaCl-water interfaces are suggested as the mechanisms.

Sun, Mao-Xu; Guo, Deng-Zhu; Xing, Ying-Jie; Zhang, Geng-Min

2012-09-01

391

On the formation of Na nanoparticles in femtosecond-laser irradiated glasses  

SciTech Connect

This work discusses the response of Na to both high-energy electrons and femtosecond-laser (fs-laser) pulses in the soda-lime glass. The evidence for different responses of Na to high-energy electron irradiation between glasses with and without fs-laser irradiation suggests that the chemical and/or physical states of Na in the fs-laser irradiated glass are different from those in the original glass. Fs-laser pulses in the glass may be able to neutralize Na, which may form clusters. These results suggest that close attention should be paid to the defects associated with Na when optical or physical data are interpreted in fs-laser irradiated Na glasses.

Jiang Nan; Su Dong; Spence, John C. H. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Qiu Jianrong [State Key Laboratory of Silicon Materials, Zhejiang University, Hongzhou 310027 (China)

2010-03-15

392

Quaternary Pnictides with Complex, Noncentrosymmetric Structures. Synthesis and Structural Characterization of the New Zintl Phases Na11Ca2Al3Sb8, Na4CaGaSb3, and Na15Ca3In5Sb12.  

PubMed

Three new Zintl phases, Na11Ca2Al3Sb8, Na4CaGaSb3, and Na15Ca3In5Sb12, have been synthesized by solid-state reactions, and their structures have been determined by single-crystal X-ray diffraction. Na11Ca2Al3Sb8 crystallizes with its own structure type (Pearson index oP48) with the primitive orthorhombic space group Pmn21 (No. 31). The structure is best viewed as [Al3Sb8](15-) units of fused AlSb4 tetrahedra, a novel type of Zintl ion, with Na(+) and Ca(2+) cations that solvate them. Na4CaGaSb3 also crystallizes in its own type with the primitive monoclinic space group Pc (No. 7; Pearson index mP36), and its structure boasts one-dimensional [GaSb3](6-) helical chains of corner-shared GaSb4 tetrahedra. The third new compound, Na15Ca3In5Sb12, crystallizes with the recently reported K2BaCdSb2 structure type (space group Pmc21; Pearson index oP12). The Na15Ca3In5Sb12 structure is based on polyanionic layers made of corner-shared InSb4 tetrahedra. Approximately one-sixth of the In sites are vacant in a statistical manner. All three structures exhibit similarities to the TiNiSi structure type, and the corresponding relationships are discussed. Electronic band structure calculations performed using the tight-binding linear muffin-tin orbital atomic sphere approximation method show small band gaps for all three compounds, which suggests intrinsic semiconducting behavior for these materials. PMID:25650866

Wang, Yi; Stoyko, Stanislav; Bobev, Svilen

2015-02-16

393

Excitation- and ?2-agonist-induced activation of the Na+?K+ pump in rat soleus muscle  

PubMed Central

In rat skeletal muscle, Na+–K+ pump activity increases dramatically in response to excitation (up to 20-fold) or ?2-agonists (2-fold), leading to a reduction in intracellular Na+. This study examines the time course of these effects and whether they are due to an increased affinity of the Na+–K+ pump for intracellular Na+. Isolated rat soleus muscles were incubated at 30 oC in Krebs-Ringer bicarbonate buffer. The effects of direct electrical stimulation on 86Rb+ uptake rate and intracellular Na+ concentration ([Na+]i) were characterized in the subsequent recovery phase. [Na+]i was varied using monensin or buffers with low Na+. In the [Na+]i range 21–69 mm, both the ?2-agonist salbutamol and electrical stimulation produced a left shift of the curves relating 86Rb+ uptake rate to [Na+]i. In the first 10 s after 1 or 10 s pulse trains of 60 Hz, [Na+]i showed no increase, but 86Rb+ uptake rate increased by 22 and 86 %, respectively. Muscles excited in Na+-free Li+-substituted buffer and subsequently allowed to rest in standard buffer also showed a significant increase in 86Rb+ uptake rate and decrease in [Na+]i. Na+ loading induced by monensin or electroporation also stimulated 86Rb+ uptake rate but, contrary to excitation, increased [Na+]i. The increase in the rate of 86Rb+ uptake elicited by electrical stimulation was abolished by ouabain, but not by bumetanide. The results indicate that excitation (like salbutamol) induces a rapid increase in the affinity of the Na+–K+ pump for intracellular Na+. This leads to a Na+–K+ pump activation that does not require Na+ influx, but possibly the generation of action potentials. This improves restoration of the Na+–K+ homeostasis during work and optimizes excitability and contractile performance of the working muscle. PMID:12433963

Buchanan, Rasmus; Nielsen, Ole Bækgaard; Clausen, Torben

2002-01-01

394

Actinic EUV mask inspection beyond 0.25 NA  

SciTech Connect

Operating at EUV wavelengths, the SEMATECH Berkeley Actinic Inspection Tool (AIT) is a zoneplate microscope that provides high quality aerial image measurements in routine operations for SEMATECH member companies. We have upgraded the optical performance of the AIT to provide multiple image magnifications, and several inspection NA values up to 0.35 NA equivalent (0.0875 mask-side). We report on the improved imaging capabilities including resolution below 100-nm on the mask side (25 nm, 4x wafer equivalent). EUV reticles are intricate optical systems made from of several materials with wavelength-specific optical properties. The combined interactions of the substrate, multilayer-stack, buffer layer and absorber layer produce a reflected EUV optical field that is challenging to model accurately, and difficult to fully assess without actinic at-wavelength inspection. Understanding the aerial image from lithographic printing alone is complicated by photoresist properties. The AIT is now used to investigate mask issues such as amplitude and phase defect printability, pattern repair techniques, contamination, inspection damage, and mask architecture. The AIT has a 6{sup o} illumination angle, and high-resolution exposure times are typically 20 seconds per image. The AIT operates semi-automatically capturing through-focus imaging series with step sizes as small as 0.1 {micro}m (0.5-0.8 {micro}m are typical), and a step resolution of 0.05 {micro}m. We believe it is the most advanced EUV mask inspection tool in operation today. In the AIT, an EUV image of the mask is projected by a zoneplate lens with high magnification (680-910x) onto a CCD camera. The CCD over-samples the image, providing equivalent pixel sizes down to 15 nm in mask coordinates-several image pixels per resolution element. The original AIT zoneplate specifications were designed to emulate the resolution of a 0.25-NA 4x stepper, and thorough benchmarking analysis of the aberrations, flare, contrast-transfer function, and coherence was published in 2007 [1] (see Fig 1). Recent upgrades have also included changes to improve the illumination uniformity and increase the partial coherence {sigma} value. Five different zoneplate lenses are installed side-by-side to enable the AIT to emulate various stepper optical properties (see Fig. 2).

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

2008-08-06

395

Structural models of Na+, Ca2+, and K+ channels.  

PubMed

The structure determination of voltage-gated channels by the combination of molecular modeling and mutagenesis experiments is a long term, iterative process. As such, the models should be considered as a work in progress, with changes expected as more data becomes available. The primary role of the models is that they assimilate the known data and provide ideas for further experiments to elucidate the real structures. Although the models presented here have already gone through two or three cycles of development and testing, many aspects remain tentative. Perhaps the most significant result so far is that the P segment was experimentally confirmed to form the ion-selective part of the channel. In a subsequent cycle of testing and modeling, the specific residues responsibility for Na+ and Ca2+ selectivity have been identified and the selectivity filter of K+ channels is now predicted to be formed by the side chains, but rather by the carbonyl oxygens of the conserved Gly-Tyr-Gly sequence backbone. As another example, the 9p residue of the P segment of K+ channels was originally modeled as either being buried in the protein or accessible channels was originally modeled as either being buried in the protein or accessible from inside the cell only. However, once mutation of this residue to histidine was found to affect blockade by extracellular TEA, protons, Zn2+ and histidine reagents (DeBiasi et al., 1993), the models were updated to have this and the hydrophilic residues in the first part of P form a helix that comprises part of the extracellular, outer vestibular of the pore. While this motif was used also for Na+ and Ca2+ pore models (see Fig. 2) where the putative helices are amphipathic, it remains to be verified. Modeling of the size and shape of the outer vestibule of K+ channels was also aided by the data for the binding of CTX in the extracellular entrance to the pore. Similarly, experiments with peptide toxins such as mu and omega conotoxins may prove useful in modeling the outer vestibules of the Na+ and/or Ca2+ channels. While important advances have been made, it is important to realize that these approaches are still very new. In the future we are likely to see improvements on both the theoretical and experimental sides which will greatly advance the process.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7676315

Guy, H R; Durell, S R

1995-01-01

396

The Na–Cu–O phase diagram in the Cu-rich part  

Microsoft Academic Search

We report the thermogravimetry data of NaCu2O2 and NaCuO compounds in Ar\\/O2 gas mixtures with different oxygen contents accompanied by X-ray analysis. Preliminary synthetic approaches for compounds in the Na–Cu–O system were developed. Combined with X-ray diffractometry of a number of specimens synthesized with compositions corresponding to the oxygen-poor area of diagram, these data enabled us to determine the Cu-rich

Andrei B. Kulakov; Andrei N. Maljuk; Mikhail Sofin; Chengtian T. Lin; Bernhard Keimer; Martin Jansen

2004-01-01

397

Reconstitution in yeast of the Arabidopsis SOS signaling pathway for Na+ homeostasis  

Microsoft Academic Search

The Arabidopsis thaliana SOS1 protein is a putative Na+\\/H+ antiporter that functions in Na+ extrusion and is essential for the NaCl tolerance of plants. sos1 mutant plants share phenotypic similarities with mutants lacking the protein kinase SOS2 and the Ca2+ sensor SOS3. To investigate whether the three SOS proteins function in the same response pathway, we have reconstituted the SOS

Francisco J. Quintero; Masaru Ohta; Huazhong Shi; Jian-Kang Zhu; Jose M. Pardo

2002-01-01

398

Changes in antioxidant levels in Oryza sativa L. roots subjected to NaCl-salinity stress  

Microsoft Academic Search

Imposition of NaCl-salinity stress induced oxidative reactions in root tissue of rice seedlings. A uniform accumulation of\\u000a proline was marked with the increasing NaCl concentrations. Both peroxide content and lipid peroxidation level (MDA) increased\\u000a with the salt treatment from the control. CAT, GPx and SOD activities decreased with the increasing NaCl concentrations suggesting\\u000a a possible oxidative damage to root tissue.

M. H. Khan; Ksh L. B. Singha; S. K. Panda

2002-01-01

399

Membrane-integral pyrophosphatase subfamily capable of translocating both Na+ and H+.  

PubMed

One of the strategies used by organisms to adapt to life under conditions of short energy supply is to use the by-product pyrophosphate to support cation gradients in membranes. Transport reactions are catalyzed by membrane-integral pyrophosphatases (PPases), which are classified into two homologous subfamilies: H(+)-transporting (found in prokaryotes, protists, and plants) and Na(+)-transporting (found in prokaryotes). Transport activities have been believed to require specific machinery for each ion, in accordance with the prevailing paradigm in membrane transport. However, experiments using a fluorescent pH probe and (22)Na(+) measurements in the current study revealed that five bacterial PPases expressed in Escherichia coli have the ability to simultaneously translocate H(+) and Na(+) into inverted membrane vesicles under physiological conditions. Consistent with data from phylogenetic analyses, our results support the existence of a third, dual-specificity bacterial Na(+),H(+)-PPase subfamily, which apparently evolved from Na(+)-PPases. Interestingly, genes for Na(+),H(+)-PPase have been found in the major microbes colonizing the human gastrointestinal tract. The Na(+),H(+)-PPases require Na(+) for hydrolytic and transport activities and are further activated by K(+). Based on ionophore effects, we conclude that the Na(+) and H(+) transport reactions are electrogenic and do not result from secondary antiport effects. Sequence comparisons further disclosed four Na(+),H(+)-PPase signature residues located outside the ion conductance channel identified earlier in PPases using X-ray crystallography. Our results collectively support the emerging paradigm that both Na(+) and H(+) can be transported via the same mechanism, with switching between Na(+) and H(+) specificities requiring only subtle changes in the transporter structure. PMID:23297210

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

2013-01-22

400

AtHKT1 Facilitates Na+ Homeostasis and K+ Nutrition in Planta1  

PubMed Central

Genetic and physiological data establish that Arabidopsis AtHKT1 facilitates Na+ homeostasis in planta and by this function modulates K+ nutrient status. Mutations that disrupt AtHKT1 function suppress NaCl sensitivity of sos1-1 and sos2-2, as well as of sos3-1 seedlings grown in vitro and plants grown in controlled environmental conditions. hkt1 suppression of sos3-1 NaCl sensitivity is linked to higher Na+ content in the shoot and lower content of the ion in the root, reducing the Na+ imbalance between these organs that is caused by sos3-1. AtHKT1 transgene expression, driven by its innate promoter, increases NaCl but not LiCl or KCl sensitivity of wild-type (Col-0 gl1) or of sos3-1 seedlings. NaCl sensitivity induced by AtHKT1 transgene expression is linked to a lower K+ to Na+ ratio in the root. However, hkt1 mutations increase NaCl sensitivity of both seedlings in vitro and plants grown in controlled environmental conditions, which is correlated with a lower K+ to Na+ ratio in the shoot. These results establish that AtHKT1 is a focal determinant of Na+ homeostasis in planta, as either positive or negative modulation of its function disturbs ion status that is manifested as salt sensitivity. K+-deficient growth of sos1-1, sos2-2, and sos3-1 seedlings is suppressed completely by hkt1-1. AtHKT1 transgene expression exacerbates K+ deficiency of sos3-1 or wild-type seedlings. Together, these results indicate that AtHKT1 controls Na+ homeostasis in planta and through this function regulates K+ nutrient status. PMID:15347798

Rus, Ana; Lee, Byeong-ha; Muñoz-Mayor, Alicia; Sharkhuu, Altanbadralt; Miura, Kenji; Zhu, Jian-Kang; Bressan, Ray A.; Hasegawa, Paul M.

2004-01-01

401

Partial purification of the Na + -dependent d -glucose transport system from renal brush border membranes  

Microsoft Academic Search

Summary  A membrane extract enriched with the Na+-dependentd-glucose transport system was obtained by differential cholate solubilization of rat renal brush border membranes in the presence of 120mm Na+ ions. Sodium ions were essential in stabilizing the transport system during cholate treatment. This membrane extract was further purified with respect to its Na+-coupledd-glucose transport activity and protein content by the use of

Wha Bin Ira; Kit Yin Ling; Robert G. Faust

1982-01-01

402

[The regulation of Na, K-ATPase activity by the substrate].  

PubMed

The mechanism of functioning of Na, K-ATPase system is considered, the peculiarities of hydrolysis in different substrates are described. The experimental results testify to the role of substrate structure in E2----E1-transition, Na+ transport, K(+)-dependent phosphatase activity and quaternary structure of enzyme. The regulatory role of molecular organization of Na, K-ATPase in ion transport is discussed. PMID:2169908

Boldyrev, A A; Lopina, O D; Fedosova, N U

1990-01-01

403

Ingestion of hypertonic NaCl vs. palatable drinks by sodium-depleted rats  

Microsoft Academic Search

This work investigated whether the preference for NaCl solution is shifted to more palatable solutions in the adult male sodium-depleted rat (n=6–10 per group). Animals had daily access to three bottles, one containing water, another 1.8% NaCl (300 mM), and a third containing 0.9% NaCl (150 mM), Gatorade (orange—OG or grape flavored—GG), orange juice (sweetened or unsweetened, from concentrate), or

Priscila N Nozaki; Daniela T. B Pereira; Flávio V Moura; José V Menani; Laurival A De Luca

2002-01-01

404

Infrared Spectroscopic Study of Adsorbed Water on Reduced-Charge Na\\/Li-Montmorillonites  

Microsoft Academic Search

Infrared (IR) spectra in the fundamental and near-IR regions were obtained for Na-saturated Wyoming montmoriUonite and reduced-charge Na\\/Li-saturated Wyoming montmorillonites hydrated un- der water vapor at 50% RH and dehydrated under vacuum. For the Na-montmorillonite, changes in the intensities of the structural OH-bending modes, particularly that of the MgA1OH group, were observed as the clay was dehydrated. This result was

Garrison Sposito; R. PROST; J.-P. GAULTIER

1983-01-01

405

Comparative proteomic analysis of NaCl stress-responsive proteins in Arabidopsis roots  

Microsoft Academic Search

NaCl stress is a major abiotic stress limiting the productivity and the geographical distribution of many plant species. Roots are the primary site of salinity perception. To understand better NaCl stress responses in Arabidopsis roots, a comparative proteo- mic analysis of roots that had been exposed to 150 mM NaCl for either 6 h or 48 h was conducted. Changes

Yuanqing Jiang; Bo Yang; Neil S. Harris; Michael K. Deyholos

2010-01-01

406

Global transcriptome profiling of wild soybean (Glycine soja) roots under NaHCO3 treatment  

Microsoft Academic Search

BACKGROUND: Plant roots are the primary site of perception and injury for saline-alkaline stress. The current knowledge of saline-alkaline stress transcriptome is mostly focused on saline (NaCl) stress and only limited information on alkaline (NaHCO3) stress is available. RESULTS: Using Affymetrix® Soybean GeneChip®, we conducted transcriptional profiling on Glycine soja roots subjected to 50 mmol\\/L NaHCO3 treatment. In a total

Ying Ge; Yong Li; Yan-Ming Zhu; Xi Bai; De-Kang Lv; Dianjing Guo; Wei Ji; Hua Cai

2010-01-01

407

Effect of Salt Stress on Growth, Na+ Accumulation and Proline Metabolism in Potato (Solanum tuberosum) Cultivars  

PubMed Central

Potato (Solanum tuberosum) is a major crop world-wide and the productivity of currently used cultivars is strongly reduced at high soil salt levels. We compared the response of six potato cultivars to increased root NaCl concentrations. Cuttings were grown hydroponically and treated with 0 mM, 60 mM and 180 mM NaCl for one week. Growth reduction on salt was strongest for the cultivars Mozart and Mona Lisa with a severe senescence response at 180 mM NaCl and Mozart barely survived the treatment. The cultivars Desiree and Russett Burbank were more tolerant showing no senescence after salt treatment. A clear difference in Na+ homeostasis was observed between sensitive and tolerant cultivars. The salt sensitive cultivar Mozart combined low Na+ levels in root and stem with the highest leaf Na+ concentration of all cultivars, resulting in a high Na+ shoot distribution index (SDI) for Mozart as compared to Desiree. Overall, a positive correlation between salt tolerance and stem Na+ accumulation was found and the SDI for Na+ points to a role of stem Na+ accumulation in tolerance. In stem tissue, Mozart accumulated more H2O2 and less proline compared to the tolerant cultivars. Analysis of the expression of proline biosynthesis genes in Mozart and Desiree showed a clear reduction in proline dehydrogenase (PDH) expression in both cultivars and an increase in pyrroline-5-carboxylate synthetase 1 (P5CS1) gene expression in Desiree, but not in Mozart. Taken together, current day commercial cultivars show promising differences in salt tolerance and the results suggest that mechanisms of tolerance reside in the capacity of Na+ accumulation in stem tissue, resulting in reduced Na+ transport to the leaves. PMID:23533673

Jaarsma, Rinse; de Vries, Rozemarijn S. M.; de Boer, Albertus H.

2013-01-01

408

Membrane-integral pyrophosphatase subfamily capable of translocating both Na+ and H+  

PubMed Central

One of the strategies used by organisms to adapt to life under conditions of short energy supply is to use the by-product pyrophosphate to support cation gradients in membranes. Transport reactions are catalyzed by membrane-integral pyrophosphatases (PPases), which are classified into two homologous subfamilies: H+-transporting (found in prokaryotes, protists, and plants) and Na+-transporting (found in prokaryotes). Transport activities have been believed to require specific machinery for each ion, in accordance with the prevailing paradigm in membrane transport. However, experiments using a fluorescent pH probe and 22Na+ measurements in the current study revealed that five bacterial PPases expressed in Escherichia coli have the ability to simultaneously translocate H+ and Na+ into inverted membrane vesicles under physiological conditions. Consistent with data from phylogenetic analyses, our results support the existence of a third, dual-specificity bacterial Na+,H+-PPase subfamily, which apparently evolved from Na+-PPases. Interestingly, genes for Na+,H+-PPase have been found in the major microbes colonizing the human gastrointestinal tract. The Na+,H+-PPases require Na+ for hydrolytic and transport activities and are further activated by K+. Based on ionophore effects, we conclude that the Na+ and H+ transport reactions are electrogenic and do not result from secondary antiport effects. Sequence comparisons further disclosed four Na+,H+-PPase signature residues located outside the ion conductance channel identified earlier in PPases using X-ray crystallography. Our results collectively support the emerging paradigm that both Na+ and H+ can be transported via the same mechanism, with switching between Na+ and H+ specificities requiring only subtle changes in the transporter structure. PMID:23297210

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

2013-01-01

409

Physiological and Biochemical Alterations in a Diazotrophic Cyanobacterium Anabaena cylindrica Under NaCl Stress  

Microsoft Academic Search

Growth, morphological variation, and liquid chromatography–photodiode array detection–mass spectrometric analysis of pigments\\u000a have been studied in a diazotrophic cyanobacterium Anabaena cylindrica in response to NaCl stress. The chlorophyll and cellular protein contents increased initially in response to 50 mM NaCl. Further increment in NaCl concentration, however, resulted in a significant decrease in both chlorophyll and cellular\\u000a protein. A. cylindrica cells

Pratiksha Bhadauriya; Radha Gupta; Surendra Singh; Prakash Singh Bisen

2007-01-01

410

RNase H mediated cleavage of RNA by cyclohexene nucleic acid (CeNA)  

Microsoft Academic Search

Cyclohexene nucleic acid (CeNA) forms a duplex with RNA that is more stable than a DNA-RNA duplex (?Tm per modification: +2°C). A cyclohexenyl A nucleotide adopts a 3'-endo conformation when introduced in dsDNA. The neighbouring deoxy- nucleotide adopts an O4'-endo conformation. The CeNA:RNA duplex is cleaved by RNase H. The Vmax and Km of the cleavage reaction for CeNA:RNA and

Birgit Verbeure; Eveline Lescrinier; Jing Wang; Piet Herdewijn

2001-01-01

411

Performance analysis of molten carbonate fuel cell using a Li\\/Na electrolyte  

Microsoft Academic Search

Several years ago, Li\\/Na carbonate (Li2CO3\\/Na2CO3) was developed as the electrolyte of molten carbonate fuel cells (MCFCs) in place of the usual Li\\/K carbonate (Li2CO3\\/K2CO3) to the advantage of a higher ionic conductivity and lower rate of cathode NiO dissolution. To estimate the potential of Li\\/Na carbonate as the MCFC electrolyte, the dependence of the cell performance on the operating

H. Morita; M. Komoda; Y. Mugikura; Y. Izaki; T. Watanabe; Y. Masuda; T. Matsuyama

2002-01-01

412

The sensitivity of apical Na + permeability in frog skin to hypertonic stress  

Microsoft Academic Search

1.Na+ transport across abdominal skins of the frog speciesRana esculenta andRana pipiens was analyzed by recording short-circuit current (Isc), transepithelial conductance (Gt), and the current noise generated by the random blockage of apical Na+ channels by the diuretic, amiloride.2.Specific Na+ current (INa) and conductance (GNa), as reflected by the amiloride-sensitive part ofIsc andGt, respectively, were markedly depressed after addition of

Walfgang Zeiske; Willy Van Driessche

1984-01-01

413

Functions of the Persistent Na + Current in Cortical Neurons Revealed by Dynamic Clamp  

Microsoft Academic Search

Many cortical neurons and other vertebrate nerve cells are equipped with a persistent Na+ current, I\\u000a NaP, which operates at membrane potentials near the action potential threshold. This current may strongly influence integration\\u000a and transduction of synaptic input into spike patterns. However, due to the lack of pharmacological tools for selective blockade\\u000a or enhancement of I\\u000a NaP, its impact on

J. F. Storm; K. Vervaeke; H. Hu; L. J. Graham

414

Experimental transformation of Na,Ca-smectite under basic conditions at 150 °C  

Microsoft Academic Search

The aim of this study is to examine the effect of various high pH solutions on smectites. The starting materials were a Na,Ca-smectite and two homoionic Na- and Ca-smectites. The experimental solutions were 0.01 m NaOH (pH 12), 1 m K2CO3 and mixtures of 1 or 3 m KCl with 10?4 or 10?2 m KOH (pH 10 or 12). To

R Mosser-Ruck; M Cathelineau

2004-01-01

415

Intracellular Na(+) inhibits volume-regulated anion channel in rat cortical astrocytes.  

PubMed

Accumulating evidence indicates that increased intracellular Na(+) concentration ([Na(+) ]i ) in astroglial cells is associated with the development of brain edema under ischemic conditions, but the underlying mechanisms are still elusive. Here, we report that in primary cultured rat cortical astrocytes, elevations of [Na(+) ]i reflecting those achieved during ischemia cause a marked decrease in hypotonicity-evoked current mediated by volume-regulated anion channel (VRAC). Pharmacological manipulations revealed that VRAC inhibition was not due to the reverse mode of the plasma membrane sodium/calcium exchanger. The negative modulation of VRAC was also observed in an astrocytic cell line lacking the predominant astrocyte water channel aquaporin 4, indicating that [Na(+) ]i effect was not mediated by the regulation of aquaporin 4 activity. The inward rectifier Cl(-) current, which is also expressed by cultured astrocytes, was not affected by [Na(+) ]i increase. VRAC depression by high [Na(+) ]i was confirmed in adult astrocytes, suggesting that it was not developmentally regulated. Altogether, these results provide the first evidence that intracellular Na(+) dynamics can modulate astrocytic membrane conductance that controls functional processes linked to cell volume regulation and add further support to the concept that limiting astrocyte intracellular Na(+) accumulation might be a favorable strategy to counteract the development of brain edema. We show that high elevation of intracellular sodium (Na(+) ) concentration in cultured rat astrocytes decreases the activity of volume-regulated anion channel (VRAC) measured by patch-clamp technique. We speculate that in ischemic conditions intracellular Na(+) elevation either through the augmented activity of the Na(+) -dependent glutamate transporter (GLT-1) or by Na(+) -permeable channels could modulate the astrocytic volume and glutamate release (Glu(-) ) regulated by VRAC. Whether VRAC inhibition is mediated through cytosolic mechanisms or by the alteration of mitochondrial activity remains to be determined. PMID:25279950

Minieri, Laura; Pivonkova, Helena; Harantova, Lenka; Anderova, Miroslava; Ferroni, Stefano

2015-02-01

416

The Lung Amiloride-Sensitive Na^+ Channel: Biophysical Properties, Pharmacology, Ontogenesis, and Molecular Cloning  

Microsoft Academic Search

Water balance in the lung is controlled via active Na^+ and Cl^- transport. Electrophysiological measurements on lung epithelial cells demonstrated the presence of a Na^+ channel that is inhibited by amiloride (K0.5 = 90 nM) and some of its derivatives such as phenamil (K0.5 = 19 nM) and benzamil (K0.5 = 14 nM) but not by ethylisopropylamiloride. An amiloride-sensitive Na^+

Nicolas Voilley; Eric Lingueglia; Guy Champigny; Marie-Genevieve Mattei; Rainer Waldmann; Michel Lazdunski; Pascal Barbry

1994-01-01

417

Preparation of porous PMMA\\/Na +–montmorillonite cation-exchange membranes for cationic dye adsorption  

Microsoft Academic Search

Porous PMMA\\/Na+–montmorillonite (MMT) cation-exchange membranes were successfully prepared by entrapment method in this study. One approach (simple mixing) was to mix commercial PMMA polymer with Na+–MMT clays in solvent for membrane preparation (Membrane A). The other approach (emulsion polymerization) was to synthesize the PMMA\\/Na+–MMT polymer composite via emulsion polymerization first, followed by membrane casting (Membrane B for Kunipia F clays

Ray-Yi Lin; Bang-Shuo Chen; Guan-Liang Chen; Jeng-Yue Wu; Hsin-Cheng Chiu; Shing-Yi Suen

2009-01-01

418

Large Diameter of Palytoxin-induced Na/K Pump Channels and Modulation of Palytoxin Interaction by Na/K Pump Ligands  

PubMed Central

Palytoxin binds to Na/K pumps to generate nonselective cation channels whose pore likely comprises at least part of the pump's ion translocation pathway. We systematically analyzed palytoxin's interactions with native human Na/K pumps in outside-out patches from HEK293 cells over a broad range of ionic and nucleotide conditions, and with or without cardiotonic steroids. With 5 mM internal (pipette) [MgATP], palytoxin activated the conductance with an apparent affinity that was highest for Na+-containing (K+-free) external and internal solutions, lowest for K+-containing (Na+-free) external and internal solutions, and intermediate for the mixed external Na+/internal K+, and external K+/internal Na+ conditions; with Na+ solutions and MgATP, the mean dwell time of palytoxin on the Na/K pump was about one day. With Na+ solutions, the apparent affinity for palytoxin action was low after equilibration of patches with nucleotide-free pipette solution. That apparent affinity was increased in two phases as the equilibrating [MgATP] was raised over the submicromolar, and submillimolar, ranges, but was increased by pipette MgAMPPNP in a single phase, over the submillimolar range; the apparent affinity at saturating [MgAMPPNP] remained ?30-fold lower than at saturating [MgATP]. After palytoxin washout, the conductance decay that reflects palytoxin unbinding was accelerated by cardiotonic steroid. When Na/K pumps were preincubated with cardiotonic steroid, subsequent activation of palytoxin-induced conductance was greatly slowed, even after washout of the cardiotonic steroid, but activation could still be accelerated by increasing palytoxin concentration. These results indicate that palytoxin and a cardiotonic steroid can simultaneously occupy the same Na/K pump, each destabilizing the other. The palytoxin-induced channels were permeable to several large organic cations, including N-methyl-d-glucamine+, suggesting that the narrowest section of the pore must be ?7.5 Å wide. Enhanced understanding of palytoxin action now allows its use for examining the structures and mechanisms of the gates that occlude/deocclude transported ions during the normal Na/K pump cycle. PMID:15024043

Artigas, Pablo; Gadsby, David C.

2004-01-01

419

In Vivo pH Regulation by a Na+/H+ Antiporter in the Halotolerant Alga Dunaliella salina 1  

PubMed Central

Na+/H+ exchange activity in whole cells of the halotolerant alga Dunaliella salina can be elicited by intracellular acidification due to addition of weak acids at appropriate external pH. The changes in both intracellular pH and Na+ were followed. Following a mild intracellular acidification, intracellular Na+ content increased dramatically and then decreased. We interpret the phase of Na+ influx as due to the activation of the plasma membrane Na+/H+ antiporter and the phase of Na+ efflux as due to an active Na+ extrusion process. The following observations are in agreement with this interpretation: (a) the Na+ influx phase was sensitive to Li+, which is an inhibitor of the Na+/H+ antiporter, did not require energy, and was insensitive to vanadate; (b) the Na+ efflux phase is energy-dependent and sensitive to the plasma membrane ATPase inhibitor, vanadate. Following intracellular acidification, a drastic decrease in the intracellular ATP content is observed that is reversed when the cells regain their neutral pH value. We suggest that the intracellular acidification-induced change in the internal Na+ concentration is due to a combination of Na+ uptake via the Na+/H+ antiporter and an active, ATPase-dependent, Na+ extrusion. The Na+/H+ antiporter seems, therefore, to play a principal role in internal pH regulation in Dunaliella. PMID:16668138

Katz, Adriana; Bental, Michal; Degani, Hadassah; Avron, Mordhay

1991-01-01

420

Neutral carrier Na+- and Ca2+-selective microelectrodes for intracellular application.  

PubMed Central

Na+- and Ca2+-selective microelectrodes were made with Simon's neutral carrier ETH 227 and ETH 1001, respectively, and their properties were studied for intracellular application. The kNaK (selectivity coefficient for Na+ with respect to K+) values of the Na+-selective microelectrodes were in the range of 0.01-0.02, which is comparable to those of recessed-tip Na+-selective glass microelectrodes. The kNaMg values of the microelectrodes were approximately 0.005 so that the interference by intracellular Mg2+ levels could be negligible. The kNaCa values were approximately 2 and the Na+-selective microelectrodes were more selective to Ca2+ than Na+. This indicates that their intracellular application requires special care to handle Ca2+ interference under certain conditions. The kNaK, kNaMg, and kNaCa values did not depend significantly on the methods used for their determination or on the ion activity levels tested. The Nicolsky equation described well the microelectrode potentials in the mixed solutions of NaCl (1-100 mM) and KCl. Potential and resistance of the microelectrodes were stable for a long period and their response time was fast. The results indicate that the Na+-selective microlectrodes are suitable for measurements of intracellular Na ion activities. Ca2+-selective microelectrode potentials at Ca2+ concentrations lower than 10(-4) M changed significantly for the first 2-3 h and then became fairly stable. The rate of the potential change was dependent on the column length of the Ca2+-selective liquid filled. Potentials of the microelectrodes varied from 10-20 mV for Ca2+ between 10(-7) and 10(-6) M concentrations, which may be the cytosolic free-Ca2+ range. With the Ca2+ concentrations greater than 10(-6) M, the microelectrodes had potential changes of approximately 30 mV or greater for a tenfold change in Ca2+ concentration. The kCaK and kCaNa values were in the ranges of 10(-5)-10(-6) and 10(-4)-10(-5), respectively. The kCaMg values were approximately 10(-7). The results show that the Ca2+-selective microelectrodes can be used for measurements of cytosolic Ca ion activities. PMID:7183334

Dagostino, M; Lee, C O

1982-01-01

421

Crystalline phase formation in metakaolinite geopolymers activated with NaOH and sodium silicate  

Microsoft Academic Search

The effect of the NaOH content and the presence of sodium silicate activators on the formation of crystalline phases from\\u000a metakaolinite-based geopolymers were studied by X-ray powder diffraction (XRD), Rietveld quantitative XRD, solid-state MAS\\u000a NMR and SEM in samples synthesized with varying NaOH contents and different curing times at 40 °C. Geopolymers activated with\\u000a NaOH alone with Si\\/Na ratios of 4\\/4

Bo Zhang; Kenneth J. D. MacKenzie; Ian W. M. Brown

2009-01-01

422

Molecular nanocrystals on ultrathin NaCl films on Au(111).  

PubMed

Direct comparison of SnPc growth on a metal and a nearly insulating surface was achieved by adsorption of SnPc on Au(111) partially covered with NaCl. While on Au(111), SnPc lies flat and grows in a Stranski-Krastanov mode; on NaCl, Volmer-Weber growth of three-dimensional molecular nanocrystals occurs. On NaCl, intermolecular interactions dominate over the molecule-NaCl coupling and result in a tilted adsorption configuration. PMID:20731345

Wang, Yongfeng; Kröger, Jörg; Berndt, Richard; Tang, Hao

2010-09-15

423

Na,K-ATPase activity modulates Src activation: a role for ATP/ADP ratio.  

PubMed

Digitalis-like compounds (DLCs), specific inhibitors of Na,K-ATPase, are implicated in cellular signaling. Exposure of cell cultures to ouabain, a well-known DLC, leads to up- or down regulation of various processes and involves activation of Src kinase. Since Na,K-ATPase is the only known target fo