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1

Vliyanie poverkhnostnogo magnitozhestkogo sloya na domennye struktury plastin ehrbievogo ortoferrita v oblasti plavnoj spinovoj pereorientatsii. (Hard-magnetic surface layer effect on the erbium orthoferrite plate domain structure in the region of gradual spin reorientation).  

National Technical Information Service (NTIS)

Rearrangement of domain structures in the erbium orthoferrite plates with hard-magnetic surface layer is investigated during gradual spin reorientation. This phenomenon is explained by means of the proposed physical models. It is shown that in these plate...

A. I. Belyaeva S. V. Vojtsenya V. P. Yur'ev

1988-01-01

2

Generation of Radiation in the 2.8 Micron M Range by Vibrational-Rotational Transition in the HF Molecule (Generatsiya Izlucheniya V Oblasti 2,8 Mkm NA Kolebatelno-Vrashchatelnykh Perekhodakh Molekuly HF).  

National Technical Information Service (NTIS)

Generation in MoF6 + H2, UF6 + H2, and F2 + H2 mixtures at pressures up to 120 mm Hg was investigated. It is shown that generation duration is considerably longer in an F2 + H2 mixture when the illumination pulse lasts for 10 micro sec. The paper deals wi...

G. G. Dolgov-Savelev V. A. Polyakov G. M. Chumak

1971-01-01

3

Rezul'taty ehksperimenta po izucheniyu chastits kosmicheskikh luchej v oblasti ehnergij E(ge)2 TEhV na ISZ Kosmos-1713 s apparaturoj Sokol-2. Pervichnye dannye. (Experimental data on study of cosmic ray particles in the E = or > 2 TeV energy range at the Kosmos-1713 satellite with the Sokol-2 device. Primary data).  

National Technical Information Service (NTIS)

Primary data of results of experiment on studying the cosmic ray particles with energy in the range exceeding 2 TeV at the Kosmos-1713 satellite using the Sokol-2 equipment are presented in the tabular form. A brief description of the equipment is given. ...

I. P. Ivanenko I. D. Rapoport V. Shestoperov

1989-01-01

4

Pervichnym rezul'tatam ehksperimenta po izucheniyu chastits kosmicheskikh luchej v oblasti ehnergij E(>=)2 TehV na ISZ KOSMOS-1713 s apparaturoj SOKOL-2. (Primary results of experiments in cosmic radiation particle investigation in the energy range E(>=)2 TeV at the KOSMOS-1713 satellite with the SOKOL-2 equipment).  

National Technical Information Service (NTIS)

The supplementary information for earlier published primary data of the experiments on high-energy cosmic radiation investigation at the KOSMOS-1713 satellite with the SOKOL-2 equipment, is given. 8 refs.; 4 tabs. (Atomindex citation 23:026338)

I. P. Ivanenko I. D. Rapoport V. Shestoperov

1990-01-01

5

\\  

Microsoft Academic Search

IZVLE?EK Avtor v prispevku predstavi, kako so povojne jugoslovanske oblasti ve?ino vodil- nih pripadnikov slovenske protifašisti?ne ilegale na Primorskem (TIGR, na Tr?aškem in v Istri Borba) obto?evale, da so \\

Gorazd BAJC

6

Na\\/K Pump Current and [Na] i in Rabbit Ventricular Myocytes: Local [Na] i Depletion and Na Buffering  

Microsoft Academic Search

Na\\/K pump current (Ipump) and intracellular Na concentration ([Na]i) were measured simultaneously in voltage-clamped rabbit ventricular myocytes, under conditions where [Na]i is controlled mainly by membrane transport. Upon abrupt pump reactivation (after 10–12min blockade), Ipump decays in two phases. Initially, Ipump declines with little [Na]i change, whereas the second phase is accompanied by [Na]i decline. Initial Ipump sag was still

Sanda Despa; Donald M. Bers

2003-01-01

7

Electrical resistance behavior of the Na-NaOH system  

Microsoft Academic Search

It was necessary to study the Na-NaOH system used in chemical and metallurgical industries in order to develop methods of preventing it from corroding structural materials. In addition, it is possible for water to enter the sodium loop of sodium-water steam generators to form NaOH, NaâO, and NaH impurities in the sodium. The impurities may markedely affect the corrosion, thermal,

O. V. Starkov; V. A. Solovev; E. A. Orlova; M. P. Filin

1982-01-01

8

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

9

Effect of ADP on Na+-Na+ Exchange Reaction Kinetics of Na,K-ATPase  

PubMed Central

The whole-cell voltage-clamp technique was used in rat cardiac myocytes to investigate the kinetics of ADP binding to phosphorylated states of Na,K-ATPase and its effects on presteady-state Na+-dependent charge movements by this enzyme. Ouabain-sensitive transient currents generated by Na,K-ATPase functioning in electroneutral Na+-Na+ exchange mode were measured at 23°C with pipette ADP concentrations ([ADP]) of up to 4.3 mM and extracellular Na+ concentrations ([Na]o) between 36 and 145 mM at membrane potentials (VM) from ?160 to +80 mV. Analysis of charge-VM curves showed that the midpoint potential of charge distribution was shifted toward more positive VM both by increasing [ADP] at constant Na+o and by increasing [Na]o at constant ADP. The total quantity of mobile charge, on the other hand, was found to be independent of changes in [ADP] or [Na]o. The presence of ADP increased the apparent rate constant for current relaxation at hyperpolarizing VM but decreased it at depolarizing VM as compared to control (no added ADP), an indication that ADP binding facilitates backward reaction steps during Na+-Na+ exchange while slowing forward reactions. Data analysis using a pseudo three-state model yielded an apparent Kd of ?6 mM for ADP binding to and release from the Na,K-ATPase phosphoenzyme; a value of 130 s?1 for k2, a rate constant that groups Na+ deocclusion/release and the enzyme conformational transition E1?P ? E2-P; a value of 162 s?1M?1 for k?2, a lumped second-order VM-independent rate constant describing the reverse reactions; and a Hill coefficient of ?1 for Na+o binding to E2-P. The results are consistent with electroneutral release of ADP before Na+ is deoccluded and released through an ion well. The same approach can be used to study additional charge-moving reactions and associated electrically silent steps of the Na,K-pump and other transporters.

Peluffo, R. Daniel

2004-01-01

10

Results from the NA61/SHINE and NA49 experiments  

NASA Astrophysics Data System (ADS)

Preliminary results on particle spectra and fluctuations in inelastic p + p interactions measured by NA61/SHINE at the CERN SPS are presented and its future ion program is discussed. We also show results on the excitation functions of event-by-event particle ratio fluctuations in central Pb + Pb collisions from NA49 using a novel approach. We found a dependence of the results on phase space coverage of the apparatus which appears to explain the reported difference between measurements of NA49 and those of STAR in central Au + Au collisions.

Rustamov, Anar

2013-05-01

11

Recent results from NA61/SHINE and NA49  

NASA Astrophysics Data System (ADS)

Preliminary results on particle spectra and fluctuations in inelastic p+p interactions measured by NA61/SHINE at the CERN SPS are presented and its future ion program is discussed. We also show results on the excitation functions of event-by-event particle ratio fluctuations in central Pb+Pb collisions from NA49 using a novel approach. We found a dependence of the results on phase space coverage which appears to explain the reported difference between measurements of NA49 and those of STAR in central Au+Au collisions.

Rustamov, Anar; Na61/Shine; Na49 Collaborations

2013-03-01

12

Linear, primary monohaloalkane chemistry in NaX and NaY faujasite zeolites with and without Na 0-treatment  

Microsoft Academic Search

This work undertakes, we believe for the first time, a study of the chemistry of alkyl halides in Na0 treated zeolites. It concludes that untreated zeolites do nucleophilic chemistry to the degree that the host is electron donating. It concludes that Na0 treated zeolites do a mixture of nucleophilic, electron-transfer, and free radical chemistry.Zeolites NaX and NaY and their Na0

Charles W. Kanyi; David C. Doetschman; Jürgen T. Schulte; Kaking Yan; Richard E. Wilson; Barry R. Jones; Chrispin O. Kowenje; Szu-Wei Yang

2006-01-01

13

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

14

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

15

Stend dlya issledovanij v oblasti zhidkoargonovoj kalorimetrii. (The test bench for testing the electromagnetic calorimeter (EMC) modules).  

National Technical Information Service (NTIS)

The description of test bench for testing the electromagnetic calorimeter modules of various configurations is given. The test bench is placed at the high-energy beam area of U-70 accelerator. The construction of the liquid argon cryostat and its outside ...

M. Bogolyubskij I. V. Boguslavskij A. Valkarova

1995-01-01

16

Deliquescence of NaCl–NaNO3, KNO3–NaNO3, and NaCl–KNO3 salt mixtures from 90 to 120°C  

Microsoft Academic Search

: We conducted reversed deliquescence experiments in saturated NaCl–NaNO3–H2O, KNO3–NaNO3–H2O, and NaCl–KNO3–H2O systems from 90 to 120°C as a function of relative humidity and solution composition. NaCl, NaNO3, and KNO3 represent members of dust salt assemblages that are likely to deliquesce and form concentrated brines on high-level radioactive waste package surfaces in a repository environment at Yucca Mountain, NV. Discrepancy

Susan Carroll; Laura Craig; Thomas J Wolery

2005-01-01

17

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

18

Hypernatremia inhibits NaHCO3 reabsorption and associated NaCl reabsorption in dogs  

Microsoft Academic Search

Hypernatremia inhibits NaHCO3 reabsorption and associated NaCl reabsorption in dogs. To examine the effect of selective rise of plasma NaCl concentration (hypematremia) on NaHCO3 reabsorption and associated NaCl reabsorption remaining during continuous ethacrynic acid infusion, hypertonic NaCl solution was infused in three groups of anesthetized volume-expanded dogs. In six dogs examined at constant hematocrit and plasma pH, bicarbonate and water

Harald Langberg; Anders Hartmann; Jonny Østensen; Øystein Mathisen; Fredrik Kiil

1986-01-01

19

Melting of the Na layers in solid Na0.8CoO2.  

PubMed

Data of 23Na NMR spectra and relaxation measurements are interpreted as suggesting that, upon increasing temperature, the Na layers in Na0.8CoO2 adopt a 2D liquid state at T=291 K. The corresponding first order phase transition is preceded by a rapidly increasing mobility and diffusion of Na ions above 200 K. Above 291 K, the 23Na NMR response is similar to that previously observed in superionic conductors with planar Na layers. PMID:19257527

Weller, M; Sacchetti, A; Ott, H R; Mattenberger, K; Batlogg, B

2009-02-02

20

Na+-stimulated ATPase of alkaliphilic halotolerant cyanobacterium Aphanothece halophytica translocates Na+ into proteoliposomes via Na+ uniport mechanism  

PubMed Central

Background When cells are exposed to high salinity conditions, they develop a mechanism to extrude excess Na+ from cells to maintain the cytoplasmic Na+ concentration. Until now, the ATPase involved in Na+ transport in cyanobacteria has not been characterized. Here, the characterization of ATPase and its role in Na+ transport of alkaliphilic halotolerant Aphanothece halophytica were investigated to understand the survival mechanism of A. halophytica under high salinity conditions. Results The purified enzyme catalyzed the hydrolysis of ATP in the presence of Na+ but not K+, Li+ and Ca2+. The apparent Km values for Na+ and ATP were 2.0 and 1.2 mM, respectively. The enzyme is likely the F1F0-ATPase based on the usual subunit pattern and the protection against N,N'-dicyclohexylcarbodiimide inhibition of ATPase activity by Na+ in a pH-dependent manner. Proteoliposomes reconstituted with the purified enzyme could take up Na+ upon the addition of ATP. The apparent Km values for this uptake were 3.3 and 0.5 mM for Na+ and ATP, respectively. The mechanism of Na+ transport mediated by Na+-stimulated ATPase in A. halophytica was revealed. Using acridine orange as a probe, alkalization of the lumen of proteoliposomes reconstituted with Na+-stimulated ATPase was observed upon the addition of ATP with Na+ but not with K+, Li+ and Ca2+. The Na+- and ATP-dependent alkalization of the proteoliposome lumen was stimulated by carbonyl cyanide m - chlorophenylhydrazone (CCCP) but was inhibited by a permeant anion nitrate. The proteoliposomes showed both ATPase activity and ATP-dependent Na+ uptake activity. The uptake of Na+ was enhanced by CCCP and nitrate. On the other hand, both CCCP and nitrate were shown to dissipate the preformed electric potential generated by Na+-stimulated ATPase of the proteoliposomes. Conclusion The data demonstrate that Na+-stimulated ATPase from A. halophytica, a likely member of F-type ATPase, functions as an electrogenic Na+ pump which transports only Na+ upon hydrolysis of ATP. A secondary event, Na+- and ATP-dependent H+ efflux from proteoliposomes, is driven by the electric potential generated by Na+-stimulated ATPase.

2010-01-01

21

Threshold electron excitation of Na  

SciTech Connect

Electron collisional excitation of the 4{ital D}, 5{ital D}, 4{ital P}, and 6{ital S} states of Na has been measured with about 30-meV energy resolution. Very rapid, unresolved threshold onsets are seen for all but the 4{ital P} state, and a near-threshold resonance is suggested by the 5{ital D} data. However, only weak undulations in the cross sections are observed above threshold.

Marinkovic, B.; Wang, P.; Gallagher, A. (Joint Institute for Laboratory Astrophysics, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 (United States))

1992-09-01

22

4-Hydroxynonenal inhibits Na +-K +ATPase  

Microsoft Academic Search

4-Hydroxynonenal binds rapidly to Na+-K+-ATPase, and this was accompanied by a decrease in measurable sulfhydryl groups and a loss of enzyme activity. The I50 value for Na+-K+-ATPase inhibition by 4-hydroxynonenal was found to be 120 ?M. Although the sulfhydryl groups could be completely restored with ?-mercaptoethanol during the reaction of the Na+K+-ATPase-HNE-adduct, the Na+-K+-ATPase activity was only partially restored by

Werner G. Siems; Sharon J. Hapner; Frederik J. G. M. Van Kuijk

1996-01-01

23

Extraction characteristics of Na and Na2 negative ions from a small multicusp ion source  

Microsoft Academic Search

Negative sodium ions and negative dimer ions of sodium are extracted from a sodium plasma. The extraction characteristics of Na? and Na2? from a low power discharge (about 1 W) through a single aperture (?1.5 mm) are described. Both extracted currents of Na? and Na2? increase with the temperature of the heat shield inside the discharge chamber. The current ratio

H. Yamaoka; M. Wada; M. Sasao; X. M. Tong; J. Fujita

1992-01-01

24

Serum stimulates the Na+,K+ pump in quiescent fibroblasts by increasing Na+ entry.  

PubMed Central

Two ionophores (monensin and gramicidin) that carry Na+ into 3T3 cells markedly enhance the rate of 86Rb+ uptake. Ouabain prevents both ionophores from increasing 86Rb+ uptake, indicating that the ionophores activate the Na+,K+ pump. Measurements of 86Rb+ uptake and cell Na+ and K+ over a range of monensin concentrations show that the activity of the Na+,K+ pump in 3T3 cells is limited by the supply of internal Na+ and is extremely sensitive to small changes in internal Na+. Serum rapidly enhances the rate of 22Na+ uptake and net Na+ entry when Na+ exit is inhibited by ouabain. At 0.3 microgram/ml, monensin increases the rate of net Na+ entry and activates the Na+,K+ pump by the same degree as serum. The stimulation of 86Rb+ uptake by serum or the ionophores has an absolute requirement for external Na+. Thus, serum appears to stimulate the Na+,K+ pump in quiescent 3T3 cells by increasing its supply of Na+.

Smith, J B; Rozengurt, E

1978-01-01

25

Photodissociation of NaH  

NASA Astrophysics Data System (ADS)

We have calculated the photodissociation cross section of NaH through the B 1? state. We have solved the time-dependent Schrödinger equation by using the Chebyshev-polynomial scheme and Fourier grid Hamiltonian method. We have used four different sets of potential-energy curves for X 1?+ and B 1? states [E. S. Sachs, J. Hinze, and N. H. Sabelli, J. Chem. Phys. 62, 3367 (1975); R. E. Olson and B. Liu, J. Chem. Phys. 73, 2817 (1980); W. C. Stwalley, W. T. Zemke, and S. C. Yang, J. Phys. Chem. Ref. Data 20, 156 (1991)]. We have found that the values of maximum photodissociation cross section and the corresponding photon energy depend on the choice of the potential-energy curves. But all these results differ significantly from an earlier calculation [K. Kirby and A. Dalgarno, Astrophys. J. 224, 444 (1978)]. We have also found that the photodissociation occurs mainly due to the Franck-Condon transitions.

Bhattacharjee, Anindita; Dastidar, Krishna Rai

2002-02-01

26

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

27

Simulation study of Na-majorite  

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

28

NA-NET numerical analysis net  

SciTech Connect

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

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

1991-12-01

29

NA-NET numerical analysis net  

SciTech Connect

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

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

1991-12-01

30

Painful Na-channelopathies: an expanding universe.  

PubMed

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

Waxman, Stephen G

2013-05-08

31

Na channel distribution in vertebrate skeletal muscle  

PubMed Central

The loose patch voltage clamp has been used to map Na current density along the length of snake and rat skeletal muscle fibers. Na currents have been recorded from (a) endplate membrane exposed by removal of the nerve terminal, (b) membrane near the endplate, (c) extrajunctional membrane far from both the endplate and the tendon, and (d) membrane near the tendon. Na current densities recorded directly on the endplate were extremely high, exceeding 400 mA/cm2 in some patches. The membrane adjacent to the endplate has a current density about fivefold lower than that of the endplate, but about fivefold higher than the membrane 100-200 micron from the endplate. Small local variations in Na current density are recorded in extrajunctional membrane. A sharp decrease in Na current density occurs over the last few hundred micrometers from the tendon. We tested the ability of tetrodotoxin to block Na current in regions close to and far from the endplate and found no evidence for toxin-resistant channels in either region. There was also no obvious difference in the kinetics of Na current in the two regions. On the basis of the Na current densities measured with the loose patch clamp, we conclude that Na channels are abundant in the endplate and near- endplate membrane and are sparse close to the tendon. The current density at the endplate is two to three orders of magnitude higher than at the tendon.

1986-01-01

32

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

Microsoft Academic Search

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

Ulf von Zahn; Edmond Murad

1990-01-01

33

Nylon 6\\/Na–montmorillonite nanocomposites prepared by compounding Nylon 6 with Na–montmorillonite slurry  

Microsoft Academic Search

We report a novel compounding process using Na–montmorillonite water slurry for preparing novel nylon 6\\/Na–montmorillonite nanocomposites. In this compounding process, the Na–montmorillonite slurry was blended with melting nylon 6 using an extruder, followed by removing the water. The Na–montmorillonite silicate layers were found to be exfoliated and dispersed homogeneously at nanometer level in the nanocomposites with an electron transmission microscope.

Naoki Hasegawa; Hirotaka Okamoto; Makoto Kato; Arimistu Usuki; Norio Sato

2003-01-01

34

Occlusion of Na+ by the Na,K-ATPase in the presence of oligomycin.  

PubMed

Oligomycin occludes Na+ in an E1-form of the Na,K-ATPase. The rate constants for the release of Na+ from the E1-form and for the transition to the E2-form are about 0.5 s-1. The effect of oligomycin is not seen using other cations which also have a Na+-like effect on the enzyme conformation. The inhibitory effect of oligomycin on the ADP-ATP dependent Na:Na exchange but not on the accompanying ADP-ATP exchange can be explained from a decrease in the rate of release of Na+ from an E1 approximately phosphoform with Na+ occluded, E'1 approximately P (Na3), i.e. with Na+ in the membrane phase, to an E"1 approximately PNa3 form with Na+ not occluded. E"1 approximately PNa3 is at a step before formation of E2-P, and disappears at a high rate when ADP reacts with E"1 approximately P (Na3). PMID:2985062

Esmann, M; Skou, J C

1985-03-29

35

Mercury's exosphere: A possible source for Na  

Microsoft Academic Search

Many ground-based observations of Na in Mercury's surface-bounded exosphere have been made and continued to be made in an effort to understand the sources, sinks, and distribution of Na around Mercury. These time consuming and costly efforts are made to better understand the physical processes on and around Mercury. A big step would be to discover an actual source of

Ann L. Sprague; Steven S. Massey

2007-01-01

36

Red cell membrane Na+ transport systems in hereditary spherocytosis: relevance to understanding the increased Na+ permeability.  

PubMed

Red blood cells (RBCs) in hereditary spherocytosis (HS) show high sodium (Na+) and potassium (K+) movement across the membrane, resulting in dehydration. In general, these abnormal cation fluxes have been interpreted as "increased leaks" due to passive or electrodiffusional permeability of the RBC membrane. A study to elucidate the contribution of concomitant ouabain-resistant pathways (Na-K-2Cl cotransport and Na-Li countertransport) to abnormal Na+ permeability present in RBCs of subjects with HS has been undertaken. Accordingly, erythrocyte Na+ and K+ content and transmembrane cation movements via the Na-K pump, Na-K-2Cl cotransport, Na-Li countertransport, and Na+ passive diffusion, were measured in 25 non-splenectomized patients with HS and compared with the results obtained from the study of 11 patients with congenital non-spherocytic haemolytic anaemia (CNSHA) due to hereditary elliptocytosis (7 cases) and RBC enzyme defects (4 cases) and of 30 normal controls. Compared to the controls, patients with HS exhibited a highly significant (P<0.001) increase in all the Na+ transmembrane movements via passive diffusion (411+/-243 vs 105+/-40), Na-K pump (2615+/-970 vs 1874+/-359), Na-K-2Cl cotransport (males: 371+/-138 vs 190+/-42; females: 401+/-134 vs 104+/-44) and Na-Li countertransport (207+/-131 vs 98+/-41). This was associated with increased Na+ and decreased K+ content, resulting in a reduction of total cation (Na+ + K+) RBC concentration. Furthermore, significant correlations were also found between the patients' RBC cationic content and the mean corpuscular haemoglobin concentration (MCHC) (r=0.51, P<0.05) and between the Na+ passive leak and the haematocrit value (r=-0.44, P<0.05). In the patients with CNSHA, a less significant (P<0.01) increase of active (Na-K pump) and passive (leak) transmembrane permeability to Na+ was associated with normal transmembrane movements via Na-K-2Cl cotransport and Na-Li countertransport. The present study demonstrates that in HS, RBCs are characterized by a variable, but always significant increase of all the membrane transport systems leading to the extrusion of Na+, and that these abnormalities, regardless of their relation to membrane structural defects, may probably be valuable for the differential diagnosis between HS and other congenital defects of RBCs. PMID:11669303

Vives Corrons, J L; Besson, I

2001-09-01

37

The NA62 RICH detector  

SciTech Connect

The NA62 experiment is designed to measure the very rare kaon decay K{sup +} {yields} {pi}{sup +} at the CERN SPS with a 10% accuracy. The Standard Model prediction for the Branching Ratio is (8.5 {+-} 0.7) x 10{sup -11}. One of the challenging aspect of the experiment is the suppression of the K{sup +} {yields} {mu}{sup +} v{sub {mu}} background at the 10{sup -12} level. To satisfy this requirement a Ring Imaging Cherenkov Detector (RICH), able to separate {pi}{sup {+-}} from {mu}{sup {+-}} in the momentum range between 15 and 35 GeV/c, with a {mu}, rejection factor better than 10{sup -2}, is needed. The RICH must also have a time resolution of about 100 ps to disentangle accidental time associations of beam particles with pions. The RICH will have a very long focal length (17 m) and will be filled with Ne gas at atmospheric pressure. Two test beams were held at CERN in 2007 and 2009 with a RICH prototype. The results of the two test beams will be presented: the {mu}, mis-identification probability is found to be about 0.7% and the time resolution better than 100 ps in the whole momentum range. (authors)

Cassese, A. [INFN Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, Universita degli Studi di Firenze (Italy)

2011-07-01

38

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

2013-09-19

39

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

40

Electrogenic Na+/Ca2+ Exchange  

PubMed Central

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

Danaceau, Jonathan P.; Lucero, Mary T.

2000-01-01

41

Laser-induced ionization of Na vapor  

SciTech Connect

The production of Na/sub 2//sup +/ ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na/sub 2/ molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na/sub 2/ D/sup 1/PI..mu.. Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na/sub 2//sup +/ ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na/sub 2//sup +/ through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na/sub 2/ molecules.

Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

1982-01-01

42

Relationship between the Na+/H+ antiporter and Na+/substrate symport in Bacillus alcalophilus.  

PubMed

The Na+/H+ antiporter of the obligate alkalophile Bacillus alcalophilus facilitates growth at alkaline pH and precludes growth below pH 8.5. Thus, nonalkalophilic mutant strains do not exhibit Na+/H+ antiport activity and, interestingly, such strains concomitantly lose the ability to catalyze Na+-dependent accumulation of alpha-aminoisobutyrate [Krulwich, T. A., Mandel, D. G. Bornstein, R. F. & Guffanti, A. A. (1979) Biochem. Biophys. Res. Commun. 91, 58-62]. Several other Na+-dependent transport systems are now documented in vesicles from the wild-type strain, and it is demonstrated that these systems are defective in vesicles from the nonalkalophilic mutant KM23. Surprisingly, the defect seems to result not from the loss of Na+/H+ antiport activity per se but from a pleiotropic defect in the Na+/substrate symporters themselves. Monensin, an ionophore that catalyzes Na+/H+ exchange, does not restore respiration-driven Na+/substrate symport in KM23 vesicles. Moreover, with KM23 vesicles, efflux of alpha-aminoisobutyrate, L-malate, and L-aspartate down their respective concentration gradients is not stimulated by Na+, in contrast to the observations with wild-type vesicles. Because monensin should ameliorate a simple defect in Na+/H+ antiport activity and the antiporter should not be required for Na+/substrate symport down a concentration gradient, the results suggest that there may be a direct relationship between the antiporter and various Na+/substrate symporters. One possibility is that the systems share a Na+-translocating subunit. PMID:6262805

Guffanti, A A; Cohn, D E; Kaback, H R; Krulwich, T A

1981-03-01

43

Na+-mediated piezoprotection in Rhodotorula rubra.  

PubMed

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

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

2003-10-01

44

Erythrocyte 22Na+ influx in hypertension  

SciTech Connect

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

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

1984-01-01

45

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

2013-10-01

46

NaI(Tl) electron energy resolution  

Microsoft Academic Search

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 662keV 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

W. Mengesha; J. D Valentine

2002-01-01

47

Anion reorientation in Na3PO4  

Microsoft Academic Search

The reorientational motion of phosphate anions in the high-temperature phase of Na3PO4 has been investigated with a coherent quasielastic neutron-scattering experiment. Our study aimed at clarifying the relevance of the so-called ``paddle-wheel'' mechanism, i.e., the influence of the anion motion on the translational Na+ ion conduction. In the Q range between 0.3 and 2.3 Å-1, the data could be fitted

D. Wilmer; R. D. Banhatti; J. Fitter; K. Funke; M. Jansen; G. Korus; R. E. Lechner

1998-01-01

48

Mercury's exosphere: A possible source for Na  

NASA Astrophysics Data System (ADS)

Many ground-based observations of Na in Mercury's surface-bounded exosphere have been made and continued to be made in an effort to understand the sources, sinks, and distribution of Na around Mercury. These time consuming and costly efforts are made to better understand the physical processes on and around Mercury. A big step would be to discover an actual source of the Na from Mercury's crust because it is already known that meteorites and comets provide Na to the exosphere through impact. We provide ground-based CCD imagery obtained with small ground-based telescopes that show bright albedo features at locations coincident with enhanced Na emissions in Mercury's exosphere. We suggest these locations are sources for Na. We also provide a mechanism to test this hypothesis using in situ observations by instruments on the MESSENGER spacecraft during the three fly bys of Mercury that will occur in 2008 and 2009, and during the orbital mission which begins in 2011. It is necessary to prove that Na is delivered to the exosphere from one or more crustal source regions before exospheric Na can be used as a measure of the volatile content of Mercury used to infer formation and evolution from the primitive solar nebula. The same applies to other elements such as K which is known to be in Mercury's exosphere and S which is postulated to be present. We expound on the impact that the discovery of one or more source regions from Mercury's crust would have on our ability to discern between the three leading models of Mercury's formation and crustal evolution.

Sprague, Ann L.; Massey, Steven S.

2007-09-01

49

Inhibition of cardiac Na+ current by primaquine  

PubMed Central

The electrophysiological effects of the anti-malarial drug primaquine on cardiac Na+ channels were examined in isolated rat ventricular muscle and myocytes.In isolated ventricular muscle, primaquine produced a dose-dependent and reversible depression of dV/dt during the upstroke of the action potential.In ventricular myocytes, primaquine blocked INa+ in a dose-dependent manner, with a Kd of 8.2??M.Primaquine (i) increased the time to peak current, (ii) depressed the slow time constant of INa+ inactivation, and (iii) slowed the fast component for recovery of INa+ from inactivation.Primaquine had no effect on: (i) the shape of the I?–?V curve, (ii) the reversal potential for Na+, (iii) the steady-state inactivation and gNa+ curves, (iv) the fast time constant of inactivation of INa+, and (v) the slow component of recovery from inactivation.Block of INa+ by primaquine was use-dependent. Data obtained using a post-rest stimulation protocol suggested that there was no closed channel block of Na+ channels by primaquine.These results suggest that primaquine blocks cardiac Na+ channels by binding to open channels and unbinding either when channels move between inactivated states or from an inactivated state to a closed state.Cardiotoxicity observed in patients undergoing malaria therapy with aminoquinolines may therefore be due to block of Na+ channels, with subsequent disturbances of impulse conductance and contractility.

Orta-Salazar, Gerardo; Bouchard, Ron A; Morales-Salgado, Fernando; Salinas-Stefanon, Eduardo M

2002-01-01

50

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

SciTech Connect

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

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

2004-10-20

51

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

Microsoft Academic Search

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

Jing-Yih Cherng; Douglas N. Bennion

1987-01-01

52

Relationship between the Na+\\/H+ Antiporter and Na+\\/Substrate Symport in Bacillus alcalophilus  

Microsoft Academic Search

The Na+\\/H+ antiporter of the obligate alkalophile Bacillus alcalophilus facilitates growth at alkaline pH and precludes growth below pH 8.5. Thus, nonalkalophilic mutant strains do not exhibit Na+\\/H+ antiport activity and, interestingly, such strains concomitantly lose the ability to catalyze Na+-dependent accumulation of alpha -aminoisobutyrate [Krulwich, T. A., Mandel, D. G. Bornstein, R. F. & Guffanti, A. A. (1979) Biochem.

Arthur A. Guffanti; Dunell E. Cohn; H. Ronald Kaback; Terry A. Krulwich

1981-01-01

53

Cellular model of proximal tubule NaCl and NaHCO3 absorption  

Microsoft Academic Search

The mammalian proximal tubule absorbs 80% of bicarbonate, 50% of NaCl, and most of the organic solutes filtered at the glomerulus. The Na-K-ATPase located on the basolateral membrane generates a low intracellular [Na] and a high intracellular [K], which in conjunction with a basolateral K conductance leads to an interior negative cell voltage. These intracellular conditions provide driving forces necessary

Orson W Moe; Patricia A Preisig; Robert J Alpern

1990-01-01

54

Novel regulation of cardiac Na pump via phospholemman.  

PubMed

As the only quantitatively significant Na efflux pathway from cardiac cells, the Na/K ATPase (Na pump) is the primary regulator of intracellular Na. The transmembrane Na gradient it establishes is essential for normal electrical excitability, numerous coupled-transport processes and, as the driving force for Na/Ca exchange, thus setting cardiac Ca load and contractility. As Na influx varies with electrical excitation, heart rate and pathology, the dynamic regulation of Na efflux is essential. It is now widely recognized that phospholemman, a 72 amino acid accessory protein which forms part of the Na pump complex, is the key nexus linking cellular signaling to pump regulation. Phospholemman is the target of a variety of post-translational modifications (including phosphorylation, palmitoylation and glutathionation) and these can dynamically alter the activity of the Na pump. This review summarizes our current understanding of the multiple regulatory. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes". PMID:23672825

Pavlovic, Davor; Fuller, William; Shattock, Michael J

2013-05-12

55

HCO3(-)-coupled Na+ influx is a major determinant of Na+ turnover and Na+/K+ pump activity in rat hepatocytes  

SciTech Connect

Recent studies in hepatocytes indicate that Na(+)-coupled HCO3- transport contributes importantly to regulation of intracellular pH and membrane HCO3- transport. However, the direction of net coupled Na+ and HCO3- movement and the effect of HCO3- on Na+ turnover and Na+/K+ pump activity are not known. In these studies, the effect of HCO3- on Na+ influx and turnover were measured in primary rat hepatocyte cultures with 22Na+, and (Na+)i was measured in single hepatocytes using the Na(+)-sensitive fluorochrome SBFI. Na+/K+ pump activity was measured in intact perfused rat liver and hepatocyte monolayers as Na(+)-dependent or ouabain-suppressible 86Rb uptake, and was measured in single hepatocytes as the effect of transient pump inhibition by removal of extracellular K+ on membrane potential difference (PD) and (Na+)i. In hepatocyte monolayers, HCO3- increased 22Na+ entry and turnover rates by 50-65%, without measurably altering 22Na+ pool size or cell volume, and HCO3- also increased Na+/K+ pump activity by 70%. In single cells, exposure to HCO3- produced an abrupt and sustained rise in (Na+)i from approximately 8 to 12 mM. Na+/K+ pump activity assessed in single cells by PD excursions during transient K+ removal increased congruent to 2.5-fold in the presence of HCO3-, and the rise in (Na+)i produced by inhibition of the Na+/K+ pump was similarly increased congruent to 2.5-fold in the presence of HCO3-. In intact perfused rat liver, HCO3- increased both Na+/K+ pump activity and O2 consumption. These findings indicate that, in hepatocytes, net coupled Na+ and HCO3- movement is inward and represents a major determinant of Na+ influx and Na+/K+ pump activity. About half of hepatic Na+/K+ pump activity appears dedicated to recycling Na+ entering in conjunction with HCO3- to maintain (Na+)i within the physiologic range.

Fitz, J.G.; Lidofsky, S.D.; Weisiger, R.A.; Xie, M.H.; Cochran, M.; Grotmol, T.; Scharschmidt, B.F. (University of California, San Francisco (USA))

1991-05-01

56

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 662keV 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 438keV, 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 (662keV). 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 16keV to 6.7% at 438keV. 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

57

NaPi-IIa and interacting partners  

PubMed Central

Regulation of renal proximal tubular reabsorption of phosphate (Pi) is one of the critical steps in Pi homeostasis. Experimental evidence suggests that this regulation is achieved mainly by controlling the apical expression of the Na+-dependent Pi cotransporter type IIa (NaPi-IIa) in proximal tubules. Only recently have we started to obtain information regarding the molecular mechanisms that control the apical expression of NaPi-IIa. The first critical observation was the finding that truncation of only its last three amino acid residues has a strong effect on apical expression. A second major finding was the observation that the last intracellular loop of NaPi-IIa contains sequence information that confers parathyroid hormone (PTH) sensitivity. The use of the above domains of the cotransporter in yeast two-hybrid (Y2H) screening allowed the identification of proteins interacting with NaPi-IIa. Biochemical and morphological, as well as functional, analyses have allowed us to obtain insights into the physiological roles of such interactions, although our present knowledge is still far from complete.

Hernando, N; Gisler, SM; Pribanic, S; Deliot, N; Capuano, P; Wagner, CA; Moe, OW; Biber, J; Murer, H

2005-01-01

58

Na clusters on metal supported Ar layers  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

59

Orientation of Na(3P) States Excited in Na-He Collisions.  

National Technical Information Service (NTIS)

The orientation of Na(3p) states created in 3-13 keV Na(3s)-He collisions has been studied by the polarized photon-scattered particle coincidence technique at scattering angles corresponding to the impact-parameter range 1-2 a.u. In the standard geometry,...

N. Andersen T. Andersen P. Dalby T. Royer

1988-01-01

60

NA and optimization for high-NA i-line lithography  

NASA Astrophysics Data System (ADS)

NA and (sigma) will be optimized to establish 0.35 micrometers i-line single layer resist process without use of super resolution techniques. Resolution, depth of focus (DOF), and proximity effect are evaluated using a variable NA and (sigma) stepper. NA is varied by an aperture stop in a projection lens. (sigma) is varied by not only an aperture stop (mechanical (sigma) ) in an illumination optics but also intensity distribution of illumination at the aperture stop (effective (sigma) ). Optimized NA and (sigma) are applied to a newly developed high resolution resist. Obtained results show that high NA and high (sigma) stepper has a great availability for 0.35 micrometers device fabrication.

Yamanaka, Koji; Iwasaki, Haruo; Nozue, Hiroshi; Kasama, Kunihiko

1993-08-01

61

Na+-Na+ exchange mediated by (Na+ + K+)-ATPase reconstituted into liposomes. Evaluation of pump stoichiometry and response to ATP and ADP.  

PubMed

(Na+ + K+)-ATPase from shark rectal glands reconstituted into lipid vesicles and oriented inside out catalyses an ouabain-sensitive Na+-Na+ exchange in the absence of intravesicular K+ when ATP is added extravesicularly. Intravesicular ouabain inhibited the exchange completely. This was also the case with digitoxigenin added to the vesicles. Intravesicular oligomycin inhibited the Na+-Na+ exchange partly in a fashion which was ATP dependent. The exchange is accompanied by a net hydrolysis of ATP with an apparent Km of 2.5 microM. ADP was found to give no stimulation of the Na+-Na+ exchange, contrarily, ADP inhibited the ATP-dependent exchange of Na+ both at optimal and supraoptimal ATP concentrations. When initial influx and efflux of 22Na was measured and the hydrolysis of ATP concomitantly determined a coupling ratio of 2.8:1.3:1 was found, i.e. 2.8 moles of Na+ were taken up (cellular efflux) and 1.3 moles of Na+ extruded (cellular influx) for each mole of ATP hydrolyzed. The electrogenic Na+-Na+ exchange generated a transmembrane potential which was measured with the fluorescent probe ANS (8-anilino-1-naphthalenesulfonic acid) to be 60 mV positive inside the liposomes (extracellular). PMID:2992589

Cornelius, F; Skou, J C

1985-08-27

62

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

63

Burning Behavior of Paper Inhibited by NaHCO3  

Microsoft Academic Search

Flaming limit of paper inhibited by chemical and thermal retardants was in vestigated. The tested retardants were sodium hydrogen carbonate (NaHCO3), sodium carbonate (Na2CO3) and water. With increasing NaHCO3 or Na2CO3, the spreading rate of flaming decreased gradually. At a critical content of 0.25 wt %, stable flaming became impossible. Beyond the critical Na content, slow but stable smoldering combustion

Muneo Izumikawa; Tohru Mitani; Takashi Noka

1986-01-01

64

Na + and Cl ? transepithelial routes in rabbit gallbladder  

Microsoft Academic Search

The reported experiments demonstrate that in rabbit gallbladder epithelium:a)The mucosa-cell Na+ and Cl- influxes (45 sec long) are reduced in Cl--free and Na+-free bathing solutions respectively; transconcentration effects are observed.b)Cell Cl- labelling through the luminal membrane, with36Cl- (1 hr incubation), is nearly abolished if a Na+-free bathing solution is used; but cell Na+ labelling with22Na+ in the lumen (1 hr

D. Cremaschi; S. Hénin

1975-01-01

65

Aldosterone (ALDO) increases transmembrane influx of Na + in vascular smooth muscle (VSM) cells through increased synthesis of Na + channels  

Microsoft Academic Search

We have previously reported our studies on glucocorticoid (GC) effects on Na+ influx in vascular smooth muscle (VSM) cells. We now report a parallel study on the effect of mineralocorticoid (MC) on Na+ influx in VSM cells. Unidirectional influx of Na+ was measured in cultured cells of rabbit aortic media with 22Na as tracer. Cells were treated with near physiologic

Ludwig Kornel; Barbara Smoszna-Konaszewska

1995-01-01

66

[Differences of physiological responses of cucumber seedlings to NaCl and NaHCO3 stress].  

PubMed

By a solution culture experiment, cucumber seedlings were treated with different concentration (0, 25, 50 and 75 mmol x L(-1)) NaCl and NaHCO3, and their physiological responses were studied. The results showed that with increasing NaCl and NaHCO3 stress, the shoot and root growth, the leaf chlorophyll content and relative water content of the seedlings decreased dramatically, and the decrements were greater under NaHCO3 than under NaCl stress. The shoot Na content increased significantly with increasing NaCl and NaHCO, stress, while shoot K+ content was in adverse. At the same concentration of Na+ in culture solution, the addition of NaHCO3 induced a greater decrement of shoot K+ content, and thus, a lower shoot K+/Na+ ratio. Under NaHCO3 stress, the leaf electrolyte leakage rate and the leaf MDA, proline, and soluble sugar contents increased much greater, compared with those under NaCl stress. Under NaCl and NaHCO3 stress, the leaf superoxide dismutase (SOD), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) activities were induced significantly, while the leaf peroxidase (POD) activity was inhibited obviously. PMID:18975769

Zhang, Li-ping; Wang, Xiu-feng; Shi, Qing-hua; Gao, Qing-hai; Liu, Ze-zhou

2008-08-01

67

Crystal structure of a Na+-bound Na+,K+-ATPase preceding the E1P state.  

PubMed

Na(+),K(+)-ATPase pumps three Na(+) ions out of cells in exchange for two K(+) taken up from the extracellular medium per ATP molecule hydrolysed, thereby establishing Na(+) and K(+) gradients across the membrane in all animal cells. These ion gradients are used in many fundamental processes, notably excitation of nerve cells. Here we describe 2.8?Å-resolution crystal structures of this ATPase from pig kidney with bound Na(+), ADP and aluminium fluoride, a stable phosphate analogue, with and without oligomycin that promotes Na(+) occlusion. These crystal structures represent a transition state preceding the phosphorylated intermediate (E1P) in which three Na(+) ions are occluded. Details of the Na(+)-binding sites show how this ATPase functions as a Na(+)-specific pump, rejecting K(+) and Ca(2+), even though its affinity for Na(+) is low (millimolar dissociation constant). A mechanism for sequential, cooperative Na(+) binding can now be formulated in atomic detail. PMID:24089211

Kanai, Ryuta; Ogawa, Haruo; Vilsen, Bente; Cornelius, Flemming; Toyoshima, Chikashi

2013-10-02

68

The electrogenic Na/HCO3 cotransporter.  

PubMed

The electrogenic Na/HCO3 cotransporter (symporter) is the major HCO3- transporter of the renal proximal tubule (PiT), located at the basolateral membrane (BLM), and also plays a noteworthy role in Na+ reabsorption. HCO3 transporters are important for regulation of intracellular pH (pHi) in most cells and also thereby regulate blood pH. This electrogenic Na/HCO3 cotransporter was first discovered using perfused Ambystoma tigrinum (salamander) renal, proximal tubules. This novel cotransporter mediates the movement of one Na+ ion with several HCO3- ions, making it electrogenic, is blocked by stilbene compounds, but does not depend on intra- or extracellular Cl-. This and similar cotransporters have been found in a number of tissues and cell types. Recently, we used Xenopus-laevis oocytes to expression clone the salamander renal electrogenic Na Bicarbonate Cotransporter (NBC). Using microelectrodes to monitor membrane potential (Vm) and intracellular pH (pHi), we followed oocyte expression after injecting poly (A)+, fractioned poly (A)+, or cRNA. All experimental solutions contained 100 microM ouabain to block the Na+/K+ pump. Our expression assay was to apply 1.5% CO2/10 mM HCO3- (pH 7.5), allow pHi to stabilize from the CO2-induced acidification, and then remove bath Na+. Removing bath Na+ from native oocytes and water-injected controls, hyperpolarized the oocytes by approximately 5 mV and had no effect on pHi. However, for oocytes injected with poly (A)+ RNA, removing Na+ transiently depolarized the cell by approximately 10 mV and caused pHi to decrease; both effects were blocked by 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS) and required HCO3-. Electrophoretic fractionation of the poly (A)+ RNA, enriched the expression signal. From the optimal expression-fraction, we constructed a size-selected cDNA library in pSPORT1. Screening our Ambystoma library yielded a single clone (aNBC). We could detect expression 3 days after injection of NBC cRNA. In aNBC-expressing oocytes, adding CO2/HCO3-elicited a large (> 50mV) and rapid hyperpolarization, followed by a partial relaxation as pHi stabilized. Na+ removal in CO2/HCO3-depolarized the cell by > 40mV and decreased pHi, aNBC encodes a protein of 1035 amino acids with several putative membrane-spanning domains, and has a low level of amino-acid homology (approximately 30% to the AE family of Cl-HCO3 exchangers. aNBC is the first member of a new family of Na(+)-linked HCO3- transporters and, together with the AE family, defines a new superfamily of HCO3- transporters. Using aNBC to screen a rat-kidney cDNA library, we identified a full-length cDNA clone (rNBC), rNBC encodes a protein of 1035 amino acids, is 86% identical to aNBC, and can be functionally expressed in oocytes. PMID:9261985

Boron, W F; Fong, P; Hediger, M A; Boulpaep, E L; Romero, M F

1997-06-27

69

High-temperature mechanical properties of porous NaMgF 3 derived from directionally solidified NaMgF 3–NaF eutectics  

Microsoft Academic Search

Porous NaMgF3 ceramics have been fabricated by leaching a NaF–NaMgF3 eutectic in distilled water, producing NaMgF3 with 53% of connected porosity. The eutectic was fabricated using the Bridgman technique at growth rates of 8, 10 and 15mm\\/h. The microstructure and composition of the resulting material has been studied by means of X-ray diffraction and SEM. Compression mechanical tests have been

J. Ramírez-Rico; A. R. de Arellano-López; J. Martínez-Fernández; A. Larrea; V. M. Orera

2008-01-01

70

Calibration of Sound and Vibration Sensors and Vibration Testing Systems  

Microsoft Academic Search

SPEKTRA is a manufacturer of high quality calibration systems for sound and vibration. Under license No DKD-K-27801, a calibration lab was established at SPEKTRA to provide a calibration service. The paper gives a summary of 4 years experience in the calibration of vibration Sensors, measuring systems and vibration test equipment in the industrial field. In practice calibration is often treated

H. Nicklich

2004-01-01

71

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

PubMed Central

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

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

2010-01-01

72

NaCl crystallization in restoration plasters  

Microsoft Academic Search

Salt crystallization is one of the most recurrent causes of damage in building materials. In this paper a study of NaCl crystallization in restoration plasters is presented. The morphology of the salt crystals, the location of salt crystallization and the decay patterns are investigated and related to the properties of the plaster and of the substrate\\/plaster combination. The research has

Barbara Lubelli; Mario R. de Rooij

2009-01-01

73

The NA60 experiment readout architecture  

Microsoft Academic Search

The NA60 experiment was designed to identify signatures of a new state of matter, the Quark Gluon Plasma, in heavy-ion collisions at the CERN Super Proton Synchroton. The apparatus is composed of four main detectors: a muon spectrometer (MS), a zero degree calorimeter (ZDC), a silicon vertex telescope (VT), and a silicon microstrip beam tracker (BT). The readout of the

Michele Floris; Davide Marras; Gianluca Usai; Andre David; Peter Rosinsky; Hiroaki Ohnishi

2004-01-01

74

Components from Na and Ca Channel Gating  

Microsoft Academic Search

Intramembrane charge movement was recorded in rat and rabbit ventricular cells using the whole-cell voltage clamp technique. Na and K currents were eliminated by using tetraethylammonium as the main cation internally and externally, and Ca channel current was blocked by Cd and La. With steps in the range of -110 to -150 used to define linear capacitance, extra charge moves

BRUCE P. BEAN; EDUARDO RIOS

1989-01-01

75

Theoretical study of Na excitation and ionization in H/sup +/+Na collisions  

SciTech Connect

Na excitation and ionization cross sections in H/sup +/+Na collisions are determined at impact energies 0.7--50 keV within the semiclassical close-coupling method with atomic-orbital basis sets including pseudostates. Calculated Na(3s..-->..3p) excitation cross sections and the 3p alignment show structures which agree very well with available experimental data. While a structure at 3 keV is predominantly caused by interaction between capture and excitation channels, interaction between excitation and ionization channels leads to a shoulder in the calculated 3p excitation cross section at higher energies and a correlated distinct dip in the predicted ionization cross section.

Fritsch, W.

1987-03-01

76

Na+/K(+)-ATPase regulation by neurotransmitters.  

PubMed

A long period of experimental work has led to the conclusion that Na+/K(+)-ATPase is the enzymatic version of the Na+/K+ pump. This enzymatic system is in charge of various important cell functions. Among them cationic equilibrium and recovering of resting membrane potential in neurons is relevant. A tetrameric ensemble of peptides conform the system known as alpha and beta subunits. The alpha subunit is subdivided in alpha 1, alpha 2 and alpha 3, according to different location and properties. Regulatory factors intrinsic to the Na+/K(+)-ATPase system are: ATP, Na+ and Mg2+ concentrations inside the cell, and K+ outside. The enzyme activity is also regulated by extrinsic factors like some hormones (insulin and thyroxine). Induction of gene expression or post-translational modifications of the preexisting pool of the enzyme are the basic mechanisms of regulation proposed. Other extrinsic factors that seem to regulate the enzyme activity are some neurotransmitters. Among them the most extensively studied are catecholamines, mainly norepinephrine (NE) and lately serotonin (5-HT). The mechanism suggested for NE activation of the enzyme seems to involve specific receptors or a non-specific chelating action related to the catechol group that would relieve the inhibition by divalent cations. Another possibility is that NE removes an endogenous inhibitory factor present in the cytoplasm. The Na+/K(+)-ATPase is activated also by 5-HT. In vivo pharmacological and nutriological manipulations of brain 5-HT are accompanied by parallel responses of Na+/K(+)-ATPase activity. Serotonin agonists do activate the enzyme and antagonists neutralize the activation. In vitro there is a different dose dependent activation, according to the brain region. The mechanism involved seems to implicate a specific receptor system. Serotonin-Na+/K(+)-ATPase interaction in the rat brain is probably of functional relevance because it disappears in amygdaloid kindling. Also it seems to influence the ionic regulation of the pigment transport mechanism in crayfish photoreceptors. In relation to other neurotransmitters, a weak response to histamine was observed with acetylcholine, GABA and glutamic acid, the results were negative. PMID:1363908

Hernández-R, J

1992-01-01

77

Laser trapping of {sup 21}Na atoms  

SciTech Connect

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

Lu, Zheng-Tian

1994-09-01

78

Thermochemical studies on the system Na-U-O  

NASA Astrophysics Data System (ADS)

Measurement of sodium vapor pressures and oxygen potentials over the three-phase fields <NaUO3>-<Na2U2O7>-<Na2UO4>, <Na2U2O7>-<Na6U7O24>-<NaUO3> and <Na6U7O24>-<NaUO3>-UO2 are made in the present study. Vapor pressure of sodium was measured by using a transpiration technique and the oxygen potential was measured by using emf (electro motive force) measurements with oxide and fluoride solid electrolytes. From the vapor pressure measurements a mean value of -1496.7 kJ mol-1 was obtained for the ?H<NaUO>° at 298 K. The ?G<NaUO>° was determined by measuring the sodium potential and the oxygen potential over the phase field <Na2U2O7>-<NaUO3>-<Na6U7O24>. The ?G<NaUO>° in the temperature range 774-1474 K was determined for the first time.

Pankajavalli, R.; Chandramouli, V.; Anthonysamy, S.; Ananthasivan, K.; Ganesan, V.

2012-01-01

79

Intracellular Na(+) and metabolic modulation of Na/K pump and excitability in the rat suprachiasmatic nucleus neurons.  

PubMed

Na/K pump activity and metabolic rate are both higher during the day in the suprachiasmatic nucleus (SCN) that houses the circadian clock. Here we investigated the role of intracellular Na(+) and energy metabolism in regulating Na/K pump activity and neuronal excitability. Removal of extracellular K(+) to block the Na/K pump excited SCN neurons to fire at higher rates and return to normal K(+) to reactivate the pump produced rebound hyperpolarization to inhibit firing. In the presence of tetrodotoxin to block the action potentials, both zero K(+)-induced depolarization and rebound hyperpolarization were blocked by the cardiac glycoside strophanthidin. Ratiometric Na(+) imaging with a Na(+)-sensitive fluorescent dye indicated saturating accumulation of intracellular Na(+) in response to pump blockade with zero K(+). The Na(+) ionophore monensin also induced Na(+) loading and hyperpolarized the membrane potential, with the hyperpolarizing effect of monensin abolished in zero Na(+) or by pump blockade. Conversely, Na(+) depletion with Na(+)-free pipette solution depolarized membrane potential but retained residual Na/K pump activity. Cyanide inhibition of oxidative phosphorylation blocked the Na/K pump to depolarize resting potential and increase spontaneous firing in most cells, and to raise intracellular Na(+) levels in all cells. Nonetheless, the Na/K pump was incompletely blocked by cyanide but completely blocked by iodoacetate to inhibit glycolysis, indicating the involvement of both oxidative phosphorylation and glycolysis in fueling the Na/K pump. Together, the results indicate the importance of intracellular Na(+) and energy metabolism in regulating Na/K pump activity as well as neuronal excitability in the SCN neurons. PMID:22773774

Wang, Yi-Chi; Yang, Jyh-Jeen; Huang, Rong-Chi

2012-07-05

80

Velocity Dependence of Na-Ar and Na-Xe Fine-Structure-Changing Collisions.  

National Technical Information Service (NTIS)

The velocity dependence of the total fine-structure-changing cross section has been measured for collisions of Na(3p) with Ar and Xe using a new velocity-selection technique based on the Doppler shift.

J. Apt D. E. Pritchard

1976-01-01

81

Red cell membrane Na + transport systems in hereditary spherocytosis: relevance to understanding the increased Na + permeability  

Microsoft Academic Search

Red blood cells (RBCs) in hereditary spherocytosis (HS) show high sodium (Na+) and potassium (K+) movement across the membrane, resulting in dehydration. In general, these abnormal cation fluxes have been interpreted as \\

J. L. Vives Corrons; I. Besson

2001-01-01

82

Transmural Gradients in Na/K Pump Activity and [Na+]i in Canine Ventricle  

PubMed Central

There are well-documented differences in ion channel activity and action potential shape between epicardial (EPI), midmyocardial (MID), and endocardial (ENDO) ventricular myocytes. The purpose of this study was to determine if differences exist in Na/K pump activity. The whole cell patch-clamp was used to measure Na/K pump current (IP) and inward background Na+-current (Iinb) in cells isolated from canine left ventricle. All currents were normalized to membrane capacitance. IP was measured as the current blocked by a saturating concentration of dihydro-ouabain. [Na+]i was measured using SBFI-AM. IP(ENDO) (0.34 ± 0.04 pA/pF, n = 17) was smaller than IP(EPI) (0.68 ± 0.09 pA/pF, n = 38); the ratio was 0.50 with IP(MID) being intermediate (0.53 ± 0.13 pA/pF, n = 19). The dependence of IP on [Na+]i or voltage was essentially identical in EPI and ENDO (half-maximal activation at 9–10 mM [Na+]i or ??90 mV). Increasing [K+]o from 5.4 to 15 mM caused both IP(ENDO) and IP(EPI) to increase, but the ratio remained ?0.5. Iinb in EPI and ENDO were nearly identical (?0.6 pA/pF). Physiological [Na+]i was lower in EPI (7 ± 2 mM, n = 31) than ENDO (12 ± 3 mM, n = 29), with MID being intermediate (9 ± 3 mM, n = 22). When cells were paced at 2 Hz, [Na+]i increased but the differences persisted (ENDO 14 ± 3 mM, n = 10; EPI 9 ± 2 mM, n = 10; and MID intermediate, 11 ± 2 mM, n = 9). Based on these results, the larger IP in EPI appears to reflect a higher maximum turnover rate, which implies either a larger number of active pumps or a higher turnover rate per pump protein. The transmural gradient in [Na+]i means physiological IP is approximately uniform across the ventricular wall, whereas transporters that utilize the transmembrane electrochemical gradient for Na+, such as Na/Ca exchange, have a larger driving force in EPI than ENDO.

Gao, J.; Wang, W.; Cohen, I. S.; Mathias, R. T.

2005-01-01

83

Furosemide-sensitive Na and K fluxes in human red cells. Net uphill Na extrusion and equilibrium properties  

PubMed Central

This paper reports experiments designed to find the concentrations of internal and external Na and K at which inward and outward furosemide- sensitive (FS) Na and K fluxes are equal, so that there is no net FS movement of Na and K. The red cell cation content was modified by using the ionophore nystatin, varying cell Na (Nai) from 0 to 34 mM (K substitution, high-K cells) and cell K (Ki) from 0 to 30 mM (Na substitution, high-Na cells). All incubation media contained NaCl (Nao = 130 or 120 nM), and KCl (Ko = 0-30 mM). In high-K cells, incubated in the absence of Ko, there was net extrusion of Na through the FS pathway. The net FS Na extrusion increased when Nai was increased. Low concentrations of Ko (0-6 mM) slightly stimulated, whereas higher concentrations of Ko inhibited, FS Na efflux. Increasing Ko stimulated the FS Na influx (K0.5 = 4 mM). Under conditions similar to those that occur in vivo (Nai = 10, Ki = 130, Nao = 130, Ko = 4 mM, Cli/Clo = 0.7), net extrusion of Na occurs through the FS pathway (180-250 mumol/liter cell X h). The concentration of Ko at which the FS Na influx and efflux and the FS K influx and efflux become equal increased when Nai increased in high-K cells and when Ki was increased in high-Na cells. The net FS Na and K fluxes both approached zero at similar internal and external Na and K concentrations. In high-K cells, under conditions when net Na and K fluxes were near zero, the ratio of FS Na to FS K unidirectional flux was found to be 2:3. In high-K cells, the empirical expression (Nai/Nao)2(Ki/Ko)3 remained at constant value (apparent equilibrium constant, Kappeq +/- SEM = 22 +/- 2) for each set of internal and external cation concentrations at which there was no net Na flux. These results indicate that in the physiological region of concentrations of internal and external Na, K, and Cl, the stoichiometry of the FS Na and K fluxes is 2 Na:3 K. In high-Na cells under conditions when net FS Na and K fluxes were near zero, the ratio of FS Na to FS K unidirectional fluxes was 3:2 (1).(ABSTRACT TRUNCATED AT 400 WORDS)

1986-01-01

84

(19)F(alpha,n)(22)Na, (22)Ne(p,n)(22)Na, and the Role of their Inverses in the Destruction of (22)Na  

NASA Astrophysics Data System (ADS)

The inverses of the 19F(?,n)22Na and 22Ne(p,n)22Na reactions may be important destruction mechanisms for 22Na in neutron-rich, high-temperature or explosive nucleosynthesis. I have measured the cross sections for the 19F(?,n)22Na and 22Ne(p,n)22Na reactions from threshold to 3.1 and 5.4 MeV, respectively. The absolute efficiency of the 4? neutron detector was determined by Monte Carlo calculations and calibrated using two standard sources and two nuclear reactions. Cross sections for the inverse reactions have been calculated using the principle of detailed balance, and reaction rates for both the reactions and their inverses determined for temperatures between 0.01 and 10 GK for 19F(?,n)22Na and between 0.1 and 10 GK for 22Ne(p,n)22Na.

Wrean, Patricia Rose

85

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.

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

2012-01-01

86

Hypo-osmotic stimulation of active Na+ transport in frog muscle: apparent upregulation of Na+ pumps.  

PubMed

The purpose of this work was to determine if hypotonicity, in addition to the stimulation of active Na+ transport (Venosa, R.A., 1978, Biochim. Biophys. Acta 510:378-383), promoted changes in (i) active K+ influx, (ii) passive Na+ and K+ fluxes, and (iii) the number of 3H-ouabain binding sites. The results indicate that a reduction of external osmotic pressure (pi) to one-half of its normal value (pi = 0.5) produced the following effects: (i) an increase in active K+ influx on the order of 160%, (ii) a 20% reduction in Na+ influx and K+ permeability (PK), and (iii) a 40% increase in the apparent density of ouabain binding sites. These data suggest that the hypotonic stimulation of the Na+ pump is not caused by an increased leak of either Na+ (inward) or K+ (outward). It is unlikely that the stimulation of active Na+ extrusion and the rise in the apparent number of pump sites produced by hypotonicity were due to a reduction of the intracellular ionic strength. It appears that, at least in part, the stimulation of active Na+ transport takes place whenever muscles are transferred from one medium to another of lower tonicity even if neither one was hypotonic (for instance pi = 2 to pi = 1 transfer). Comparison of the present results with those previously reported indicate that in addition to the number of pump sites, the cycling rate of the pump is increased by hypotonicity. Active Na+ and K+ fluxes were not significantly altered by hypertonicity (pi = 2). PMID:2072389

Venosa, R A

1991-03-01

87

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

NASA Astrophysics Data System (ADS)

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.

1987-09-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

89

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

SciTech Connect

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

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

1989-04-01

90

A marine algal Na(+)-activated ATPase possesses an immunologically identical epitope to Na+,K(+)-ATPase.  

PubMed

Immunological homology was investigated between Heterosigma akashiwo (a marine algae) Na(+)-activated ATPase and animal Na+,K(+)-ATPase. The former polypeptide [(1989) Plant Cell Physiol. 30, 923-928] reacted with anti-serum raised against the amino-terminal half of the pig kidney Na+,K(+)-ATPase alpha subunit. It is suggested that the Na+,K(+)-ATPase epitope within the amino-terminal region is conserved in the plant Na(+)-activated ATPase, and the region containing the epitope may be important for Na ion transport. PMID:1381322

Wada, M; Urayama, O; Satoh, S; Hara, Y; Ikawa, Y; Fujii, T

1992-09-14

91

Thermodynamic representation of the NaCl + Na 2SO 4 + H 2O system with electrolyte NRTL model  

Microsoft Academic Search

A comprehensive thermodynamic model based on the electrolyte NRTL (eNRTL) activity coefficient equation is developed for the NaCl+H2O binary, the Na2SO4+H2O binary and the NaCl+Na2SO4+H2O ternary. The NRTL binary parameters for pairs H2O–(Na+, Cl?) and H2O–(Na+, SO42?), and the aqueous phase infinite dilution heat capacity parameters for ions Cl? and SO42? are regressed from fitting experimental data on mean ionic

Yizhuan Yan; Chau-Chyun Chen

2011-01-01

92

{beta} decay of {sup 32}Na  

SciTech Connect

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

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

2007-01-15

93

Slip casting alumina with Na-CMC  

SciTech Connect

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

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

1996-11-01

94

Na + \\/H + Exchanger and Myocardial Hypertrophy  

Microsoft Academic Search

\\u000a Na+\\/H+ exchanger (NHE) is hyperactive in the hypertensive hypertrophied myocardium. Regression of cardiac hypertrophy (CH) induced\\u000a by prolonged antihypertensive therapy with compounds of different pharmacological profiles (angiotensin converting enzyme\\u000a inhibition, slow calcium channel and angiotensin II type 1 receptor blockade) normalizes the hyperactivity of myocardial NHE.\\u000a Chronic treatment with selective NHE-1 inhibitors induced the regression of CH in SHR. Considered

María C. Camilión de Hurtado; Néstor G. Pérez; Irene L. Ennis; Bernardo V. Alvarez; Horacio E. Cingolani

95

Excitonic emission from CsI(Na)  

Microsoft Academic Search

Photoluminescence in CsI(Na) was studied. This work used nonionizing light sources and obtained the data from well-annealed zone-refined specimens. A series of excitation and emission spectra were measured at temperatures between 300 and 4.2°K. The emission spectra consist of the characteristic blue emission and other low-temperature emissions. The emission spectra were decomposed into the superposition of Gaussian peaks by computer.

Olive Lee Hsu; Clayton W. Bates Jr.

1977-01-01

96

Spectral composition of thermoluminescence of coloured NaCl crystals  

Microsoft Academic Search

The paper gives the experimental results of studying the spectral composition of thermoluminescence in the different maxima in photo-chemically coloured “pure” NaCl crystals or NaCl-crystals containing Cu in different concentrations.

J. Dolejsí; A. Bohun

1960-01-01

97

U. S. EPAâ??S NA APPROACH FOR PETROLEUM HYDROCARBONS  

EPA Science Inventory

Most evaluations of NA of petroleum hydrocarbons use geochemical data to document the NA through biodegradation. The expected trends during biodegradation (plume interior vs. background concentrations) are Dissolved oxygen concentrations below background, Nitrate concentrations ...

98

Inelastic and reactive collisions with polarized excited Na atoms  

SciTech Connect

Polarization effects in inelastic collisions of laser state-prepared Na(3/sup 2/P, M/sub J/) with Na/sup +/ leading to Na(3/sup 2/D) or Na(3/sup 2/S) are discussed for the energy range E/sub cm/ = 5-47.5eV. Studies with linearly polarized light can be explained with a simple ''locking'' model of the Na(P)-orbital. The investigations employing circularly polarized light are a very sensitive test of the models describing the nonadiabatic angular momentum coupling between electronic and nuclear motion. The dynamical effects of the electronic spin on the angular momentum transfer are discussed. Recent crossed-beam experiments on the Na + O/sub 2/ -> NaO = O reaction in the energy range E/sub cm/ = 0/3-0.8eV show a pronounced dependence on the electric electronic symmetry of Na. 17 refs., 11 figs.

Schmidt, H.; Hertel, I.V.; Lee, Y.T.

1985-07-01

99

Regulation of Epithelial Sodium Transport via Epithelial Na+ Channel  

PubMed Central

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

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

2011-01-01

100

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

101

Conformational changes couple Na+ and glucose transport.  

PubMed

The mechanism by which cotransport proteins couple their substrates across cell membranes is not known. A commonly proposed model is that cotransport results from ligand-induced conformational transitions that change the accessibility of ligand-binding sites from one side of the membrane to the other. To test this model, we have measured the accessibility of covalent probes to a cysteine residue (Q457C) placed in the putative sugar-translocation domain of the Na+/glucose cotransporter (SGLT1). The mutant protein Q457C was able to transport sugar, but transport was abolished after alkylation by methanethiosulfonate reagents. Alkylation blocked sugar translocation but not sugar binding. Accessibility of Q457C to alkylating reagents required external Na+ and was blocked by external sugar and phlorizin. The voltage dependence of accessibility was directly correlated with the presteady-state charge movement of SGLT1. Voltage-jump experiments with rhodamine-6-maleimide-labeled Q457C showed that the time course and level of changes in fluorescence closely followed the presteady-state charge movement. We conclude that conformational changes are responsible for the coupling of Na+ and sugar transport and that Q457 plays a critical role in sugar translocation by SGLT1. PMID:9636229

Loo, D D; Hirayama, B A; Gallardo, E M; Lam, J T; Turk, E; Wright, E M

1998-06-23

102

Conformational changes couple Na+ and glucose transport  

PubMed Central

The mechanism by which cotransport proteins couple their substrates across cell membranes is not known. A commonly proposed model is that cotransport results from ligand-induced conformational transitions that change the accessibility of ligand-binding sites from one side of the membrane to the other. To test this model, we have measured the accessibility of covalent probes to a cysteine residue (Q457C) placed in the putative sugar-translocation domain of the Na+/glucose cotransporter (SGLT1). The mutant protein Q457C was able to transport sugar, but transport was abolished after alkylation by methanethiosulfonate reagents. Alkylation blocked sugar translocation but not sugar binding. Accessibility of Q457C to alkylating reagents required external Na+ and was blocked by external sugar and phlorizin. The voltage dependence of accessibility was directly correlated with the presteady–state charge movement of SGLT1. Voltage-jump experiments with rhodamine-6-maleimide-labeled Q457C showed that the time course and level of changes in fluorescence closely followed the presteady–state charge movement. We conclude that conformational changes are responsible for the coupling of Na+ and sugar transport and that Q457 plays a critical role in sugar translocation by SGLT1.

Loo, Donald D. F.; Hirayama, Bruce A.; Gallardo, Elsa M.; Lam, Jason T.; Turk, Eric; Wright, Ernest M.

1998-01-01

103

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

104

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.

Vedovato, Natascia

2010-01-01

105

23Na multiple quantum filtered NMR characterisation of Na+ binding and dynamics in animal cells: a comparative study and effect of Na+/Li + competition.  

PubMed

Double quantum and triple quantum filtered (23)Na nuclear magnetic resonance techniques were used to characterise in detail the isotropic and anisotropic binding and dynamics of intra- and extracellular Na(+) in different cellular systems, in the absence and presence of Li(+). The kinetics of Li(+) influx by different cell types was evaluated. At steady state, astrocytes accumulated more Li(+) than red blood cells (RBCs), while a higher intracellular Li(+) concentration was found in chromaffin than in SH-SY5Y cells. Anisotropic and isotropic motions were detected for extracellular Na(+) in all cellular systems studied. Isotropic intracellular Na(+) motions were observed in all types of cells, while anisotropic Na(+) motions in the intracellular compartment were only detected in RBCs. (23)Na triple quantum signal efficiency for intracellular Na(+) was SH-SY5Y > chromaffin > RBCs, while the reverse order was observed for the extracellular ions. (23)Na double quantum signal efficiency for intracellular Na(+) was non-zero only in RBCs, and for extracellular Na(+) the order RBCs > chromaffin > SH-SY5Y cells was observed. Li(+) loading generally decreased intracellular Na(+) isotropic movements in the cells, except for astrocytes incubated with a low Li(+) concentration and increased anisotropic intracellular Na(+) movements in RBCs. Li(+) effects on the extracellular signals were more complex, reflecting Li(+)/Na(+) competition for isotropic and anisotropic binding sites at the extracellular surface of cell membranes and also at the surface of the gel used for cell immobilisation. These results are relevant and contribute to the interpretation of the in vivo pharmacokinetics and sites of Li(+) action. PMID:23563802

Fonseca, Carla P; Fonseca, Luís L; Montezinho, Liliana P; Alves, Paula M; Santos, Helena; Castro, M Margarida C A; Geraldes, Carlos F G C

2013-04-06

106

Igneous origin for the NA in the cloud of Io  

NASA Astrophysics Data System (ADS)

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

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

1990-06-01

107

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

Microsoft Academic Search

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

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

1989-01-01

108

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)

2013-01-01

109

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

110

Effects of Na 2CO 3 and NaOH on DSC thermal profiles of selected native cereal starches  

Microsoft Academic Search

The effects of Na2CO3 and NaOH (at a concentration of 1 g alkalising agent\\/100 g dry starch) on the gelatinisation properties of 1:4 and 2:3 starch\\/water mixtures were studied using differential scanning calorimetry (DSC). The starches studied included wheat, rice, waxy rice, corn and waxy corn. The addition of Na2CO3 or NaOH resulted in significant increases in transition temperatures (onset,

L. N. Lai; A. Abd Karim; M. H. Norziah; C. C. Seow

2002-01-01

111

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

PubMed Central

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

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

2012-01-01

112

Kinetics of Na(+) transport in necturus proximal tubule  

PubMed Central

The dependence of proximal tubular sodium and fluid readsorption on the Na(+) concentration of the luminal and peritubular fluid was studied in the perfused necturus kidney. Fluid droplets, separated by oil from the tubular contents and identical in composition to the vascular perfusate, were introduced into proximal tubules, reaspirated, and analyzed for Na(+) and [(14)C]mannitol. In addition, fluid transport was measured in short-circuited fluid samples by observing the rate of change in length of the split droplets in the tubular lumen. Both reabsorptive fluid and calculated Na fluxes were simple, storable functions of the perfusate Na(+) concentration (K(m) = 35-39 mM/liter, V(max) = 1.37 control value). Intracellular Na(+), determined by tissue analysis, and open-circuit transepithelial electrical potential differences were also saturable functions of extracellular Na(+). In contrast, net reabsorptive fluid and Na(+) fluxes were linearly dependent on intracellular Na(+) and showed no saturation, even at sharply elevated cellular sodium concentrations. These concentrations were achieved by addition of amphotericin B to the luminal perfusate, a maneuver which increased the rate of Na(+) entry into the tubule cells and caused a proportionate rise in net Na(+) flux. It is concluded that active peritubular sodium transport in proximal tubule cells of necturus is normally unsaturated and remains so even after amphotericin-induced enhancement of luminal Na(+) entry. Transepithelial movement of NaCl may be described by a model with a saturable luminal entry step of Na(+) or NaCl into the cell and a second, unsaturated active transport step of Na(+) across the peritubular cell boundary.

Spring, KR; Giebisch, G

1977-01-01

113

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

2013-07-25

114

Hydration valve controlled non-selective conduction of Na + and K + in the NaK channel  

Microsoft Academic Search

The Na+ and K+ channels are essential to neural signaling, but our current knowledge at the atomic level is mainly limited to the conducting mechanism of K+. Unlike a K+ channel having four equivalent K+-binding sites in its selectivity filter, a NaK channel has a vestibule in the middle part of its selectivity filter, and can conduct both Na+ and

Rong Shen; Wanlin Guo; Wenyu Zhong

2010-01-01

115

Sympathetic Cooling of Na+ Ions by Ultra-cold Na Atoms in a Hybrid trap  

NASA Astrophysics Data System (ADS)

Closed shell ions like Na+, as well as many molecular ions, cannot be easily laser cooled, for spectroscopy, quantum gates, and near zero-K reaction studies. We report on experiments studying collisions between trapped ions and trapped cold atoms. The ion-atom interaction is dominated by long-range polarization forces, principally a term V ˜-? /R^4, ? being the dipole polarizability of the neutral. The Hybrid trap consists of a linear Paul ion trap, set to trap Na+ ions, centered on a sodium magneto-optical trap (MOT). We investigate the sympathetic cooling of the (equal atomic mass) Na+ ion cloud concentric with the MOT, using either the 3s F=2->3p F^'=3 or the 3s F=2->3p F^'= 2 MOT transitions. The lifetime of the ions in the Paul trap is observed to be detectably longer when they are sympathetically cooled by the cold neutral MOT atoms, consistent with simulations via SIMION.

Sivarajah, Ilamaran; Goodman, Douglas; Wells, James; Smith, Winthrop

2011-11-01

116

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

SciTech Connect

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

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

1989-11-01

117

23Na NMR studies of doped nasicon systems  

NASA Astrophysics Data System (ADS)

The positions of sodium ions in two doped nasicon systems were investigated by using 23Na solid state NMR techniques. The 23Na NMR spectra with a characteristic powder pattern of quadrupole interaction in the Na 1- XZr 2- XNb XP 3O 12 system indicated that sodium ions occupy Na(1) sites in the crystal structure. For the Na 1 + 2 XZr 2- XMg XP 3O 12 system, excepting the compound with X = 0.1, Gaussian lineshapes were observed due to the distribution of quadrupole parameters and the occupation of both Na(1) and Na(2) sites in the crystal structure. Two sodium sites can be distinguished by applying an inversion-recovery experiment.

Yue, Yong; Deng, Feng; Hu, Hongbin; Ye, Choahui

1995-03-01

118

Strange particle measurements at the CERN SPS - NA49 and NA61/SHINE experiments  

NASA Astrophysics Data System (ADS)

Strangeness production in heavy-ion collisions has always been an important observable for probing the state of matter created in these collisions. In particular, relative strangeness production, its event-by-event fluctuations as well as their dependence on the collision energy and centrality are sensitive probes of the deconfinement phase transition.This contribution presents selected NA49 and NA61/SHINE results on strangeness production in central Pb + Pb collisions and p + p interactions in the SPS energy range. Special attention is given to data on particle ratios and ratio fluctuations as well as K*, K resonance production.

Stefanek, Grzegorz

2013-09-01

119

Polarization and velocity dependence of associative ionization in Na(3 p)+Na(3 p) collisions  

NASA Astrophysics Data System (ADS)

We have excited Na atoms of two counterrunning thermal beams by means of linearly polarized laser light and have investigated associative ionization processes. To this end we measured the total ionization signal as a function of the angle ? between light polarization and the relative collision velocity. Velocities of the excited atoms were selected by exploiting the Doppler effect. We found an increasing polarization dependence at increasing collision velocities. At all velocities the preparation of the collision partners in the | M j |=1/2 sublevel of the Na2 P 3/2 state is most efficient in producing ionization.

Meijer, H. A. J.; van der Meulen, H. P.; Morgenstern, R.

1987-12-01

120

0 and 1 ?? shell model description of the 22Na and 23Na isotopes  

NASA Astrophysics Data System (ADS)

The USD shell model interaction has been very successful to describe the properties of positive parity states in sd nuclei using sd model space and 16O core. Recently, we have developed in Strasbourg a new interaction called PSDPF in the complete p-sd-pf valence space with 4He core, with the aim to extend the shell model description to negative parity states throughout the sd shell. As an example, results are presented for the 22Na and 23Na isotopes. Calculated energy spectra are compared to the most recent experimental results for well known normal 0 ?? and intruder 1 ?? states.

Haouam, M. R.; Bouhelal, M.; Haas, F.; Caurier, E.; Nowacki, F.

2012-06-01

121

Gill (Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in the gilthead bream (Sparus auratus L.).  

PubMed

1. Gilthead gill 10(-3) M ouabain-inhibited (Na+ + K+)-ATPase and 10(-2) M ouabain-insensitive Na+-ATPase require the optimal conditions of pH 7.0, 160 mM Na+, 20 mM K+, 5 mM MgATP and pH 4.8-5.2, 75 mM Na+, 2.5 mM Mg2+, 1.0 mM ATP, respectively. 2. The main distinctive features between the two activities are confirmed to be optimal pH, the ouabain-sensitivity and the monovalent cation requirement, Na+ plus another cationic species (K+, Rb+, Cs+, NH4+) in the (Na+ + K+)-ATPase and only one species (Na+, K+, Li+, Rb+, Cs+, NH4+ or choline+) in the Na+-ATPase. 3. The aspecific Na+-ATPase activation by monovalent cations, as well as by nucleotide triphosphates, opposed to the (Na+ + K+)-ATPase specificity for ATP and Na+, relates gilthead gill ATPases to lower organism ATPases and differentiates them from mammalian ones. 4. The discrimination between the two activities by the sensitivity to ethacrynic acid, vanadate, furosemide and Ca2+ only partially agrees with the literature. 5. Present findings are viewed on the basis of the ATPase's presumptive physiological role(s) and mutual relationship. PMID:2158872

Ventrella, V; Trombetti, F; Pagliarani, A; Trigari, G; Borgatti, A R

1990-01-01

122

Na(+),K (+)-ATPase as a docking station: protein-protein complexes of the Na(+),K (+)-ATPase.  

PubMed

The Na(+),K(+)-ATPase, or sodium pump, is well known for its role in ion transport across the plasma membrane of animal cells. It carries out the transport of Na(+) ions out of the cell and of K(+) ions into the cell and thus maintains electrolyte and fluid balance. In addition to the fundamental ion-pumping function of the Na(+),K(+)-ATPase, recent work has suggested additional roles for Na(+),K(+)-ATPase in signal transduction and biomembrane structure. Several signaling pathways have been found to involve Na(+),K(+)-ATPase, which serves as a docking station for a fast-growing number of protein interaction partners. In this review, we focus on Na(+),K(+)-ATPase as a signal transducer, but also briefly discuss other Na(+),K(+)-ATPase protein-protein interactions, providing a comprehensive overview of the diverse signaling functions ascribed to this well-known enzyme. PMID:22695678

Reinhard, Linda; Tidow, Henning; Clausen, Michael J; Nissen, Poul

2012-06-14

123

Effect of a high NaCl diet on the active mechanisms of Na+ extrusion in rat kidney.  

PubMed

Healthy male rats were exposed to a chronic ingesta of an isotonic NaCl solution during a period of four months. Two different preparations were utilized to study the effect of this treatment on the active mechanisms of Na+ reabsorption of kidney proximal tubular cells: outermost kidney cortex slices (rich in proximal tubules) and inside-out basolateral plasma membrane vesicles prepared from the same tissue. It was found that the activity of the ouabain-insensitive, Na-pump of basolateral plasma membranes of kidney proximal tubular cells was increased in about 70%, whereas the ouabain-sensitive, Na,K-pump activity did not change with the experimental treatment. These results represent a strong support to the two Na-pump's hypothesis since the treatment affected the Na-pump differentially without affecting the Na,K-pump. PMID:2431190

Marín, R; Obando, M A; Proverbio, T; Proverbio, F

1986-10-01

124

Dependence of the NaCl/Au(111) interface state on the thickness of the NaCl layer.  

PubMed

We investigated the growth and the electronic properties of crystalline NaCl layers on Au(111) surfaces by means of cryogenic scanning tunneling microscopy and spectroscopy under ultra-high vacuum conditions. Deposition of NaCl on Au(111) at room temperature yields bilayer NaCl islands, which can be transformed into trilayer NaCl islands by post-annealing. Upon NaCl adsorption, the Au(111) Shockley surface state becomes an interface state (IS) at the NaCl/Au(111) interface. Using Fourier-transform images of maps of the local density of states, the energy versus wave vector dispersions of the IS and the Au(111) bulk states are determined. The dispersion of both states is found to depend strongly on the thickness of the adsorbed NaCl layer. PMID:23110874

Lauwaet, Koen; Schouteden, Koen; Janssens, Ewald; Van Haesendonck, Chris; Lievens, Peter

2012-10-31

125

Na? transport in the normal and failing heart - remember the balance.  

PubMed

In the heart, intracellular Na(+) concentration ([Na(+)]i) is a key modulator of Ca(2+) 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(+)/Ca(2+) 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. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes." PMID:23608603

Despa, Sanda; Bers, Donald M

2013-04-19

126

Anion reorientation in Na3PO4  

NASA Astrophysics Data System (ADS)

The reorientational motion of phosphate anions in the high-temperature phase of Na3PO4 has been investigated with a coherent quasielastic neutron-scattering experiment. Our study aimed at clarifying the relevance of the so-called ``paddle-wheel'' mechanism, i.e., the influence of the anion motion on the translational Na+ ion conduction. In the Q range between 0.3 and 2.3 Å-1, the data could be fitted by the sum of a ? function and a single Lorentzian whose width exhibits an Arrhenius behavior with an activation energy of 0.184 eV. We have calculated Sq(Q,?), the coherent quasielastic structure factor of the oxygen ions, based on several models. A comparison of the model predictions with our experimental data shows that only three oxygen atoms per anion are rotationally mobile. The experiment yields an additional small maximum around 1.5 Å-1, which appears more pronounced at higher temperatures. Its position on the Q scale suggests that sodium ions, further away from the center of rotation, are involved in the reorientational anion motion.

Wilmer, D.; Banhatti, R. D.; Fitter, J.; Funke, K.; Jansen, M.; Korus, G.; Lechner, R. E.

1998-04-01

127

[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

128

Theoretical calculation of low-lying states of NaAr and NaXe  

NASA Astrophysics Data System (ADS)

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.

1981-07-01

129

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.

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

2012-01-01

130

Hydrogen sulfide induced disruption of Na+ homeostasis in the cortex.  

PubMed

Maintenance of ionic balance is essential for neuronal functioning. Hydrogen sulfide (H(2)S), 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 H(2)S 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 H(2)S 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 H(2)S-induced Na(+) influx, suggesting that H(2)S-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

2012-04-02

131

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

PubMed Central

The ? subunits of voltage-gated Na channels (Scnxb) regulate the gating of pore-forming ? subunits, as well as their trafficking and localization. In heterologous expression systems, ?1, ?2, and ?3 subunits influence inactivation and persistent current in different ways. To test how the ?4 protein regulates Na channel gating, we transfected ?4 into HEK cells stably expressing NaV1.1. Unlike a free peptide with a sequence from the ?4 cytoplasmic domain, the full-length ?4 protein did not block open channels. Instead, ?4 expression favored open states by shifting activation curves negative, decreasing the slope of the inactivation curve, and increasing the percentage of non-inactivating current. Consequently, persistent current tripled in amplitude. Expression of ?1 or chimeric subunits including the ?1 extracellular domain, however, favored inactivation. Co-expressing NaV1.1 and ?4 with ?1 produced tiny persistent currents, indicating that ?1 overcomes the effects of ?4 in heterotrimeric channels. In contrast, ?1C121W, which contains an extracellular epilepsy-associated mutation, did not counteract the destabilization of inactivation by ?4, and also required unusually large depolarizations for channel opening. In cultured hippocampal neurons transfected with ?4, persistent current was slightly but significantly increased. Moreover, in ?4-expressing neurons from Scn1b and Scn1b/Scn2b null mice, entry into inactivated states was slowed. These data suggest that ?1 and ?4 have antagonistic roles, the former favoring inactivation and the latter favoring activation. Because increased Na channel availability may facilitate action potential firing, these results suggest a mechanism for seizure susceptibility of both mice and humans with disrupted ?1 subunits.

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

2009-01-01

132

Associação entre trauma por perda na infância e depressão na vida adulta Association between childhood loss trauma and depression in adulthood  

Microsoft Academic Search

Observações clínicas efetuadas por psicanalistas sugerem que psicopatologias da idade adulta podem ter sido originadas na infância. Estudos publicados na última década identificaram associação entre trauma na infância e depressão na vida adulta. Vivências traumáticas na infância, como a perda de vínculos afetivos devido à morte de pais ou de irmãos ou, ainda, a privação de um ou de ambos

Maria Lucrécia; Scherer Zavaschia; Fabíola Satlerb; Daniela Poesterc; Cláudia Ferrão; Rafael Piazenskib Vargasd; Luís Augusto Paim Rohdee; Cláudio Laks Eizirikf

133

NA Nonlinear Equation-of-state Inversion  

NASA Astrophysics Data System (ADS)

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

Jackson, I.; Kennett, B. L.

2008-12-01

134

Coordinated regulation of cardiac Na(+)/Ca (2+) exchanger and Na (+)-K (+)-ATPase by phospholemman (FXYD1).  

PubMed

Phospholemman (PLM) is the founding member of the FXYD family of regulators of ion transport. PLM is a 72-amino acid protein consisting of the signature PFXYD motif in the extracellular N terminus, a single transmembrane (TM) domain, and a C-terminal cytoplasmic tail containing three phosphorylation sites. In the heart, PLM co-localizes and co-immunoprecipitates with Na(+)-K(+)-ATPase, Na(+)/Ca(2+) exchanger, and L-type Ca(2+) channel. The TM domain of PLM interacts with TM9 of the ?-subunit of Na(+)-K(+)-ATPase, while its cytoplasmic tail interacts with two small regions (spanning residues 248-252 and 300-304) of the proximal intracellular loop of Na(+)/Ca(2+) exchanger. Under stress, catecholamine stimulation phosphorylates PLM at serine(68), resulting in relief of inhibition of Na(+)-K(+)-ATPase by decreasing K(m) for Na(+) and increasing V(max), and simultaneous inhibition of Na(+)/Ca(2+) exchanger. Enhanced Na(+)-K(+)-ATPase activity lowers intracellular Na(+), thereby minimizing Ca(2+) overload and risks of arrhythmias. Inhibition of Na(+)/Ca(2+) exchanger reduces Ca(2+) efflux, thereby preserving contractility. Thus, the coordinated actions of PLM during stress serve to minimize arrhythmogenesis and maintain inotropy. In acute cardiac ischemia and chronic heart failure, either expression or phosphorylation of PLM or both are altered. PLM regulates important ion transporters in the heart and offers a tempting target for development of drugs to treat heart failure. PMID:23224879

Cheung, Joseph Y; Zhang, Xue-Qian; Song, Jianliang; Gao, Erhe; Chan, Tung O; Rabinowitz, Joseph E; Koch, Walter J; Feldman, Arthur M; Wang, JuFang

2013-01-01

135

Pyrophosphate-fueled Na+ and H+ transport in prokaryotes.  

PubMed

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

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

2013-06-01

136

Interaction between Na and Li in ZnO  

NASA Astrophysics Data System (ADS)

The interaction between group-Ia elements in ZnO have been studied by implanting Na into hydrothermally grown ZnO samples containing ~4×1017 Li/cm3 and employing secondary ion mass spectrometry for sample analysis. Postimplantation annealing above 500 °C results in a diffusion of Na and concurrently Li is efficiently depleted from the regions occupied by Na. The data show unambiguously that Na and Li compete for the same trapping site and the results provide strong experimental evidence for that the formation energies of Na on Zn site together with that of interstitial Li are lower than those of Li on Zn site and interstitial Na in highly resistive ZnO. This conclusion is also supported by recent theoretical estimates of the formation energies of these species as a function of the Fermi-level position in ZnO.

Neuvonen, Pekka T.; Vines, Lasse; Kuznetsov, Andrej Yu.; Svensson, Bengt G.; Du, Xiaolong; Tuomisto, Filip; Hallén, Anders

2009-12-01

137

Symbiodinium isolation by NaOH treatment.  

PubMed

The presence of photosynthetic zooxanthellae (dinoflagellates) in the tissue of many cnidarians is the main reason for their ecological success (i.e. coral reefs). It could also be the main cause of their demise, as the worldwide bleaching of reef-building coral is nothing less than the breakdown of this symbiotic association. The stability of this relationship is the principal marker for the biomonitoring of cnidarian health. We have therefore developed a new, simple method to isolate zooxanthellae in a few steps using NaOH solution. The protocol was validated in three symbiotic cnidarian species: a sea anemone, a gorgonian and a coral. Our method allows the isolation of intact and viable zooxanthellae with better yields than classic methods, especially for species with a calcareous skeleton. Moreover, the isolated zooxanthellae were free of host nucleic contaminants, facilitating subsequent specific molecular analyses. PMID:22972880

Zamoum, Thamilla; Furla, Paola

2012-09-12

138

The NA62 experiment at CERN  

NASA Astrophysics Data System (ADS)

The Branching Ratio (BR) of the rare decay K+ ? ?+?bar nu is predicted with a small error in the framework of the standard model (SM). The contribution of long distance terms is suppressed thanks to the GIM mechanism and the short distance dynamics is almost completely described by well measured semileptonic operators. The cleanness of the SM prediction together with the small BR (~ 10-10) makes this decay an interesting opportunity to describe the presence and the contribution of the new physics using relatively low energy processes. The NA62 experiment at CERN aims at measuring O(100) events in two years of data taking with 10% background. From an experimental point of view this measurement is very challenging because the weakness of the signal signature and the huge amount of background processes. In this paper the key points of the experiment will be described after a brief introduction on theoretical aspects and present results.

Lamanna, Gianluca

2011-12-01

139

Pion and kaon freezeout in NA44  

SciTech Connect

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

NA44 Collaboration

1994-12-01

140

Influence of pellicle on hyper-NA imaging  

Microsoft Academic Search

In the case of hyper-NA (NA>1) imaging with the lens magnification keeping 1\\/4, the angle of light incidence on pellicle becomes bigger. For example, it is up to 19 degrees for NA=1.3 lens. It is already known that the effect of multiple reflections of the light inside the pellicle film becomes obvious, in that the effect contains transmission variation across

Kazuya Sato; Satoshi Nagai; Nakagawa Shinichiro; Takashi Sato; Masamitsu Itoh

2008-01-01

141

Ionic dissociation of NaCl on frozen water  

Microsoft Academic Search

Low-energy reactive ion scattering (RIS) experiments show that NaCl dissociates almost completely on condensed ice surfaces prepared on Ru(001) even at 100 K forming solvated ions. NaCl by itself does not dissociate on a Ru(001) substrate; however, submonolayer coverages of water sets-in dissociation. Na+ ions thus created are immobile such that they do not migrate across one water bilayer (BL)

Seong-Chan Park; T. Pradeep; H. Kang

2000-01-01

142

Continuum radiation and potentials of Na-noble gas molecules  

Microsoft Academic Search

The normalized emission spectra resulting from the perturbation of Na atoms by 1-1000 Torr of noble gas have been measured in the range 10-150 nm about the 589 nm resonance line. This spectrum, due to the A-X and B-X transitions of the Na-noble gas molecules, was measured with 1.5 nm resolution. The Na, in a cell at a temperature of

George York; Richard Scheps; Alan Gallagher

1975-01-01

143

Effect of nitroso compounds on Na\\/K-ATPase  

Microsoft Academic Search

Thiol containing NO?-derivatives were found to inhibit the activity of brain and kidney Na\\/K-ATPase. S-Nitrosogluthatione demonstrated only minor inhibiting activity, while dinitrosyl iron complexes (DNIC) with cysteine or glutathione were much more effective. Brain Na\\/K-ATPase is more vulnerable to inhibiting action than kidney Na\\/K-ATPase. Inhibition of the activity is accompanied by a decrease in amount of protein thiol groups and

Alexander A Boldyrev; Elena R Bulygina; Galina G Kramarenko; Anatoly F Vanin

1997-01-01

144

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, II, R. W.

1979-01-01

145

Thermodynamic Properties of NaCl Solutions at Subzero Temperatures  

Microsoft Academic Search

Heat capacities at infinite dilution of NaCl (aq) for the temperature range 0 to -25°C and apparent molar volumes at infinite dilution for 0 to -15°C have been estimated from a synthesis of experimental data collected at subzero temperatures. The parameters of the Helgeson–Kirkham–Flowers (HKF) equation for Na+ (aq) have been obtained, from which the Gibbs energies of Na+ and

Nikolai N. Akinfiev; Mikhail V. Mironenko; Steven A. Grant

2001-01-01

146

Mercury's Na Exosphere from MESSENGER data  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

147

Topology of the type IIa Na+/P(i) cotransporter.  

PubMed

The type IIa Na(+)/P(i) cotransporter (NaPi-IIa) plays a key role in the reabsorption of inorganic phosphate (P(i)) in the renal proximal tubule. The rat NaPi-IIa isoform is a protein of 637 residues for which different algorithms predict 8-12 transmembrane domains (TMDs). Epitope tagging experiments demonstrated that both the N and the C termini of NaPi-IIa are located intracellularly. Site-directed mutagenesis revealed two N-glycosylation sites in a large putative extracellular loop. Results from structure-function studies suggested the assembly of two similar opposed regions that possibly constitute part of the substrate translocation pathway for one phosphate ion together with three sodium ions. Apart from these topological aspects, other structural features of NaPi-IIa are not known. In this study, we have addressed the topology of NaPi-IIa using in vitro transcription/translation of HK-M0 and HK-M1 fusion vectors designed to test membrane insertion properties of cDNA sequences encoding putative NaPi-IIa TMDs. Based on the results of in vitro transcription/translation analyses, we propose a model of NaPi-IIa comprising 12 TMDs, with both N and C termini orientated intracellularly and a large hydrophilic extracellular loop between the fifth and sixth TMDs. The proposed model is in good agreement with the prediction of the NaPi-IIa structure obtained by the hidden Markov algorithm HMMTOP. PMID:17206517

Radanovic, Tamara; Gisler, Serge M; Biber, Jürg; Murer, Heini

2007-01-06

148

Atomistic mechanisms of phase separation and formation of solid solutions: model studies of NaCl, NaCl-NaF, and Na(Cl1-xBrx) crystallization from the melt.  

PubMed

The crystallization of sodium chloride from its melt and mixtures with other sodium halides is investigated by means of transition path sampling molecular dynamics simulations. From this we explore the nucleation mechanisms of both the solidification and the melting process at the atomistic level of detail. By incorporation of impurities the nucleation picture of the eutectic mixtures changes considerably. Doping the NaCl crystal with fluoride ions, we observed the substitutional defects to act as favored nucleation centers for the melting transition. This phenomenon plays a critical role during the solidification process of NaCl-NaF melts of low NaF concentration and is demonstrated to account for the segregation of fluoride ions. While NaCl-NaF corresponds to a eutectic system, we also investigated NaCl-NaBr mixtures. The bromide ions were observed to behave very similarly to chloride ions. As a consequence, no phase separation occurs and Na(Cl1-xBrx) solid solutions are formed. At the example of these two prototypes we demonstrate the study of the atomistic mechanisms related to phase separation processes and solid solution formation during the nucleation and growth of crystals from multinary melts. PMID:17439270

Zahn, Dirk

2007-04-18

149

Study of OSL in NaF: Ca,Cu  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

150

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

151

The Physiological Relevance of Na+-Coupled K+-Transport.  

PubMed Central

Plant roots utilize at least two distinct pathways with high and low affinities to accumulate K+. The system for high-affinity K+ uptake, which takes place against the electrochemical K+ gradient, requires direct energization. Energization of K+ uptake via Na+ coupling has been observed in algae and was recently proposed as a mechanism for K+ uptake in wheat (Triticum aestivum L.). To investigate whether Na+ coupling has general physiological relevance in energizing K+ transport, we screened a number of species, including Arabidopsis thaliana L. Heynh. ecotype Columbia, wheat, and barley (Hordeum vulgare L.), for the presence of Na+-coupled K+ uptake. Rb+-flux analysis and electrophysiological K+-transport assays were performed in the presence and absence of Na+ and provided evidence for a coupling between K+ and Na+ transport in several aquatic species. However, all investigated terrestrial species were able to sustain growth and K+ uptake in the absence of Na+. Furthermore, the addition of Na+ was either without effect or inhibited K+ absorption. The latter characteristic was independent of growth conditions with respect to Na+ status and pH. Our results suggest that in terrestrial species Na+-coupled K+ transport has no or limited physiological relevance, whereas in certain aquatic angiosperms and algae this type of secondary transport energization plays a significant role.

Maathuis, FJM.; Verlin, D.; Smith, F. A.; Sanders, D.; Fernandez, J. A.; Walker, N. A.

1996-01-01

152

Formation of ultracold fermionic NaLi Feshbach molecules  

NASA Astrophysics Data System (ADS)

We describe the formation of fermionic NaLi Feshbach molecules from an ultracold mixture of bosonic 23Na and fermionic 6Li. Precise magnetic field sweeps across a narrow Feshbach resonance at 745 G result in a molecule conversion fraction of 5% for our experimental densities and temperatures, corresponding to a molecule number of 5×104. The observed molecular decay lifetime is 1.3 ms after removing free Li and Na atoms from the trap. Due to its extremely low reactivity, NaLi molecules in the ground state will have a much longer lifetime than KRb.

Heo, Myoung-Sun; Wang, Tout T.; Christensen, Caleb A.; Rvachov, Timur M.; Cotta, Dylan A.; Choi, Jae-Hoon; Lee, Ye-Ryoung; Ketterle, Wolfgang

2012-08-01

153

Mutant N143P Reveals How Na+ Activates Thrombin*  

PubMed Central

The molecular mechanism of thrombin activation by Na+ remains elusive. Its kinetic formulation requires extension of the classical Botts-Morales theory for the action of a modifier on an enzyme to correctly account for the contribution of the E*, E, and E:Na+ forms. The extended scheme establishes that analysis of kcat unequivocally identifies allosteric transduction of Na+ binding into enhanced catalytic activity. The thrombin mutant N143P features no Na+-dependent enhancement of kcat yet binds Na+ with an affinity comparable to that of wild type. Crystal structures of the mutant in the presence and absence of Na+ confirm that Pro143 abrogates the important H-bond between the backbone N atom of residue 143 and the carbonyl O atom of Glu192, which in turn controls the orientation of the Glu192-Gly193 peptide bond and the correct architecture of the oxyanion hole. We conclude that Na+ activates thrombin by securing the correct orientation of the Glu192-Gly193 peptide bond, which is likely flipped in the absence of cation. Absolute conservation of the 143–192 H-bond in trypsin-like proteases and the importance of the oxyanion hole in protease function suggest that this mechanism of Na+ activation is present in all Na+-activated trypsin-like proteases.

Niu, Weiling; Chen, Zhiwei; Bush-Pelc, Leslie A.; Bah, Alaji; Gandhi, Prafull S.; Di Cera, Enrico

2009-01-01

154

The dissociation of phosphoric acid in NaCl and NaMgCl solutions at 25°C  

Microsoft Academic Search

The pK1*, pK1* and pK3* for the dissociation of H3PO4 have been measured in NaCl solutions from 0.5 to 6m at 25°C. The results have been used to evaluate Pitzer interaction parameters ?(NaClH2PO4)=-0.028±0.005, ?(NaH3PO4)=-0.075±0.025, ?(HPO4Cl)=0.105±0.009, ?(PO4Cl)=-0.59±0.02 and ?(NaClHPO4)=-0.003±0.004, ?(PO4NaClH)=0.110±0.008. These parameters yield values of pK1*, pK2* and pK3* in NaCl that agree with the measured values with average deviations of

J. Peter Hershey; Marino Fernandez; Frank J. Millero

1989-01-01

155

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

PubMed

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

Guerra, Denis Lima; Pinto, Alane Azevedo; de Souza, Janaína Azevedo; Airoldi, Claudio; Viana, Rúbia Ribeiro

2008-12-09

156

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

PubMed

The ability of Na2CO3 and NaCl to enhance the sulfur capture capacity of three limestones was evaluated via fixed-bed calcination and sulfation experiments. The tested limestones represent three different sulfation morphologies: unreacted-core, network, and uniformly sulfated. Treatment with aqueous or powdered Na2CO3 significantly increased the Ca-utilization for two stones which normally sulfate in an unreacted-core pattern (20% to 45%) and network pattern (33% to 49%). The increase was lower for the uniformly sulfated stone (44% to 48%). Na2CO3 treatment increased the number of macropores leading to uniform sulfation of all particles, nearly eliminating the normal strong dependence of utilization on limestone type and particle size. The effect of Na2CO3 is believed to be associated with formation of a eutectic melt which enhances ionic diffusion and accelerates molecular rearrangement of the CaO. Treatment with aqueous NaCl solution caused a decrease in utilization, probably due to formation of large grains and plugging of pores caused by formation of a large amount of eutectic melt. The effect of Na2CO3 is less sensitive than that of NaCl to the amount added and the combustion environment (temperature and gas composition). In addition, Na2CO3 neither promotes corrosion nor forms chlorinated byproducts, which are main concerns associated with NaCl. Thus, Na2CO3 appears to have significant advantages over NaCl for enhancement of limestone sulfur capture capacity in fluidized-bed combustors. PMID:11718362

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

2001-11-01

157

(2 × 1)Na surface reconstruction induced by NaCl dissociation on Ag(1 1 0) during LEED analysis  

Microsoft Academic Search

This study first reports the initial growth stages of sodium chloride (NaCl) on Ag(110) at room temperature. NaCl grows in bi-layer mode along its [100] axis and gives rise to (4×1) and (1×2) reconstructed domains for coverages lower than two monolayers (ML), a minimal thickness inducing a bi-dimensional closed film. In addition, a 10ML NaCl film has been examined by

K. Aït-Mansour; M. Bielmann; O. Gröning; P. Ruffieux; R. Fasel; P. Gröning

2006-01-01

158

Changes in Na + , K + ATPase Activity and Alpha 3 Subunit Expression in CNS After Administration of Na + , K + ATPase Inhibitors  

Microsoft Academic Search

The expression of Na+, K+-ATPase ?3 subunit and synaptosomal membrane Na+, K+-ATPase activity were analyzed after administration of ouabain and endobain E, respectively commercial and endogenous Na+, K+-ATPase inhibitors. Wistar rats received intracerebroventricularly ouabain or endobain E dissolved in saline solution or Tris–HCl,\\u000a respectively or the vehicles (controls). Two days later, animals were decapitated, cerebral cortex and hippocampus removed\\u000a and

María Geraldina Bersier; Clara Peña; Georgina Rodríguez de Lores Arnaiz

2011-01-01

159

Hypocalciuric Effects of Hydrochlorothiazide in the Rat during NaHCO3, NaCl and NH4C1 Loading  

Microsoft Academic Search

Hydrochlorothiazide (HCTZ) and NaHCO3 each lower urinary calcium excretion, while NaCl and NH4Cl each increase urinary calcium. This study examines the ability of HCTZ to lower urinary calcium during NaHCO3, NaCl and NH4Cl loading in the rat. We show that HCTZ lowers urinary calcium in rats treated with NaHCO3, NaCl and NH4Cl. We demonstrate that urinary calcium excretion is depressed

Ailsa Goulding; Dianne Campbell

1984-01-01

160

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

Microsoft Academic Search

The self-wetting properties of ionic crystal surfaces are studied, using NaCl(100) as a prototype case. The anomalously large contact angle measured long ago by Mutaftschiev [Surf. Sci. 47 (1975) 723; J. Cryst. Growth 182 (1997) 205] is well reproduced by realistic molecular dynamics simulations. Based on these results, and on independent determinations of the liquid–vapor (?LV) and the solid–vapor interface

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

2004-01-01

161

NaCl nanodroplet on NaCl(100) at the melting point  

Microsoft Academic Search

The self-wetting properties of ionic crystal surfaces are studied, using NaCl(100) as a prototype case. The anomalously large contact angle measured long ago by Mutaftschiev is well reproduced by realistic molecular dynamics simulations. Based on these results, and on independent determinations of the liquid-vapor and the solid-vapor interface free energy, an estimate of the solid-liquid interface free energy is extracted.

T. Zykovatiman

2004-01-01

162

NaCl nanodroplet on NaCl(100) at the melting point  

Microsoft Academic Search

The self-wetting properties of ionic crystal surfaces are studied, using NaCl(100) as a prototype case. The anomalously large contact angle measured long ago by Mutaftschiev (1,2) is well reproduced by realistic molecular dynamics simulations. Based on these results, and on independent determinations of the liquid-vapor (LV) and the solid-vapor interface free energy (SV) (3), an estimate of the solid-liquid interface

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

2008-01-01

163

Measurement of the quenching factor of Na recoils in NaI(Tl)  

Microsoft Academic Search

Measurements of the quenching factor for sodium recoils in a 5 cm diameter NaI(Tl) crystal at room temperature have been made at a dedicated neutron facility at the University of Sheffield. The crystal has been exposed to 2.45 MeV mono-energetic neutrons generated by a Sodern GENIE 16 neutron generator, yielding nuclear recoils of energies between 10 and 100 keVnr. A

H. Chagani; P. Majewski; E. J. Daw; V. A. Kudryavtsev; N. J. C. Spooner

2008-01-01

164

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

SciTech Connect

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

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

1995-06-01

165

A Putative Multisubunit Na+/H+ Antiporter from Staphylococcus aureus  

PubMed Central

We cloned several genes encoding an Na+/H+ antiporter of Staphylococcus aureus from chromosomal DNA by using an Escherichia coli mutant, lacking all of the major Na+/H+ antiporters, as the host. E. coli cells harboring plasmids for the cloned genes were able to grow in medium containing 0.2 M NaCl (or 10 mM LiCl). Host cells without the plasmids were unable to grow under the same conditions. Na+/H+ antiport activity was detected in membrane vesicles prepared from transformants. We determined the nucleotide sequence of the cloned 7-kbp region. We found that seven open reading frames (ORFs) were necessary for antiporter function. A promoter-like sequence was found in the upstream region from the first ORF. One inverted repeat followed by a T-cluster, which may function as a terminator, was found in the downstream region from the seventh ORF. Neither terminator-like nor promoter-like sequences were found between the ORFs. Thus, it seems that the seven ORFs comprise an operon and that the Na+/H+ antiporter consists of seven kinds of subunits, suggesting that this is a novel type of multisubunit Na+/H+ antiporter. Hydropathy analysis of the deduced amino acid sequences of the seven ORFs suggested that all of the proteins are hydrophobic. As a result of a homology search, we found that components of the respiratory chain showed sequence similarity with putative subunits of the Na+/H+ antiporter. We observed a large Na+ extrusion activity, driven by respiration in E. coli cells harboring the plasmid carrying the genes. The Na+ extrusion was sensitive to an H+ conductor, supporting the idea that the system is not a respiratory Na+ pump but an Na+/H+ antiporter. Introduction of the plasmid into E. coli mutant cells, which were unable to grow under alkaline conditions, enabled the cells to grow under such conditions.

Hiramatsu, Toshiaki; Kodama, Kazuyo; Kuroda, Teruo; Mizushima, Tohru; Tsuchiya, Tomofusa

1998-01-01

166

Moderate temperature rechargeable NaNiS2 cells  

Microsoft Academic Search

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.

K. M. Abraham

1983-01-01

167

Moderate temperature rechargeable NaNiS2 cells  

NASA Astrophysics Data System (ADS)

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.

1983-10-01

168

Vacancy Migration and Spin Lattice Relaxation in NaF.  

National Technical Information Service (NTIS)

The author reports preliminary results of measurements of spin lattice relaxation time (T1) of Na23 nucleus in NaF single crystals. The measurement of relaxation times was carried out on a phase coherent pulsed NMR spectrometer at a resonant frequency of ...

K. L. Murty

1969-01-01

169

Differential Expression of Ileal Na +\\/H + Exchanger Isoforms after Enterectomy  

Microsoft Academic Search

Background. Na+\\/H+ exchangers (NHE) are transporters involved in the absorption of NaCl along the gastrointestinal tract. The aim of this study was to determine the expression pattern of the intestinal brush border NHE isoforms 2 and 3 following massive small bowel resection (SBR). Additionally, the effect of epidermal growth factor (EGF) and salivarectomy (removal of the primary source of EGF)

Richard A. Falcone; Cathy E. Shin; Lawrence E. Stern; Zhaohui Wang; Christopher R. Erwin; Manoocher Soleimani; Brad W. Warner

1999-01-01

170

Functional and Molecular Characteristics of Na+-dependent Nucleoside Transporters  

Microsoft Academic Search

Nucleoside transporters play a critical role in the absorption, disposition, and targeting of therapeutically used nucleosides and nucleoside analogs. This review is focused on the Na+-dependent, concentrative nucleoside transporters which are found in a variety of cells including renal, intestinal and hepatic epithelia. Five major Na+-dependent nucleoside transporter subtypes have been characterized in isolated tissue preparations: Nl is purine selective;

Juan Wang; Marci E. Schaner; Silja Thomassen; Sheng-Fang Su; Micheline Piquette-Miller; Kathleen M. Giacomini

1997-01-01

171

The Origin of Mah?y?na Buddhism  

Microsoft Academic Search

Mah?y?na is a field of Buddhism accepted widely throughout northern and eastern Asia. Much of the western adepts and practitioners also perceive its significance. This article, therefore, is written and aimed to elaborate the origin of Mah?y?na Buddhism by means of \\

Sumalee Mahanarongchai

172

Comparative studies of etching mechanisms of CR-39 in NaOH/H2O 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/H2O). 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/H2O. In the present work, mass spectrometry results have shown that the same etched products are present in the etchants of NaOH/H2O 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/H2O 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

173

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

SciTech Connect

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

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

1990-01-01

174

Binding energy and geometry of e^+Na  

NASA Astrophysics Data System (ADS)

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

Shertzer, Janine; Ward, S. J.

2010-03-01

175

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

2012-10-13

176

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.

Murphy, Elizabeth; Eisner, David A.

2009-01-01

177

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

178

The Kinetics of Ca-Na Exchange in Excitable Tissue  

PubMed Central

A model is proposed to describe the Na-Ca exchange in excitable tissues. The present scheme requires a carrier mechanism that exchanges 3Na for 1Ca across the membrane under the electrochemical gradient of Na. The carriers, assumed to be trivalent anions, have monovalent and divalent sites; Ca and Na can compete only at the second site. The partially and fully loaded carrier-ion complexes are mobile and diffusible across the membrane. Subsequently, analytical expressions for Na and Ca unidirectional flux at steady state are derived in terms of intracellular concentration (Nai and Cai) and extracellular concentration (Nao and Cao) as well as membrane potential, EM. Published experimental flux data on cardiac muscle, squid axon, and rat synaptosomes can be satisfactorily fitted with the flux equation simply by adjusting the numerical constants.

Wong, Alan Y. K.; Bassingthwaighte, James B.

2010-01-01

179

Mesospheric Na layer at extreme high latitudes in summer  

NASA Astrophysics Data System (ADS)

Summertime observations of the mesospheric Na layer at high latitudes are reported from the 1993 Airborne Noctilucent Cloud (ANLC-93) campaign in the Canadian Arctic and at the Amundsen-Scott South Pole Station. Measurements at the South Pole reveal a layer that has a smaller column abundance and is significantly higher and thinner than at midlatitudes. Using a model that was essentially optimized to wintertime conditions at high northern latitudes, the South Pole layer can be modeled satisfactorily if the rate coefficient for the reaction between sodium bicarbonate and atomic hydrogen is set to k(NaHCO3 + H ? Na + H2O + CO2) = 1.1 × 10-11 exp (-910/T) cm3 molecule-1 s-1. In particular, the model is able to reproduce the small scale height of about 2 km observed on the underside of the layer. It is then shown that this steep gradient in the atomic Na mixing ratio can be sustained against vertical eddy diffusion because of the sufficiently rapid chemical cycling between Na its major reservoir, NaHCO3. This justifies the assumption in the model that the vertical transport of Na species can be treated in terms of a single continuity equation describing total sodium. The observations from the campaigns in both hemispheres show that the Na abundance has a temperature dependence of about 2 × 108 cm-2 K-1 at temperatures below 170 K, in good accord with the model. About 40% of this dependence appears to be caused by the activation energies of the reactions that partition sodium between atomic Na and NaHCO3, and the remainder by the temperature dependence of the odd-oxygen/odd-hydrogen chemistry in the upper mesosphere.

Plane, John M. C.; Cox, Rachel M.; Qian, Jun; Pfenninger, William M.; Papen, George C.; Gardner, Chester S.; Espy, Patrick J.

1998-03-01

180

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

181

KIDNEY AND URINARY BLADDER RESPONSES OF FRESHWATER RAINBOW TROUT TO ISOSMOTIC NaCI AND NaHCO3 INFUSION  

Microsoft Academic Search

Summary The relative roles of the kidney and urinary bladder in ion, fluid and acid-base regulation were examined in freshwater rainbow trout chronically infused with either 140mmoll~' NaCI or 140mmoll-' NaHCCb (3 ml kg\\

B. JAMES CURTIS; CHRIS M. WOOD

1992-01-01

182

Equations of state for solid NaCl-KCl and liquid NaCl-KCl-H(sub 2)O.  

National Technical Information Service (NTIS)

The equilibrium between the solid solution of NaCl-KCl and the ternary liquid NaCl-KCl-H(sub 2)O is both scientifically interesting and geologically important. Equations of the Margules type have been derived for the two phases that accurately reproduce t...

K. S. Pitzer S. M. Sterner

1991-01-01

183

Physico-Chemical Properties of NaF-AlF3-BaCl2-NaCl Electrolyte System.  

National Technical Information Service (NTIS)

To reduce energy consumption, the physico-chemical properties of NaF-AlF3-BaCl2-NaCl system were systematically studied. The mathematical models of the liquidus temperature and electrical conductivity were obtained and the density was also studied about t...

G. H. Li D. Li

1994-01-01

184

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

PubMed

In Necturus gallbladder epithelium, lowering serosal [Na+] ([Na+]s) reversibly hyperpolarized the basolateral cell membrane voltage (Vcs) and reduced the fractional resistance of the apical membrane (fRa). Previous results have suggested that there is no sizable basolateral Na+ conductance and that there are apical Ca(2+)-activated K+ channels. Here, we studied the mechanisms of the electrophysiological effects of lowering [Na+]s, in particular the possibility that an elevation in intracellular free [Ca2+] hyperpolarizes Vcs by increasing gK+. When [Na+]s was reduced from 100.5 to 10.5 mM (tetramethylammonium substitution), Vcs hyperpolarized from -68 +/- 2 to a peak value of -82 +/- 2 mV (P less than 0.001), and fRa decreased from 0.84 +/- 0.02 to 0.62 +/- 0.02 (P less than 0.001). Addition of 5 mM tetraethylammonium (TEA+) to the mucosal solution reduced both the hyperpolarization of Vcs and the change in fRa, whereas serosal addition of TEA+ had no effect. Ouabain (10(-4) M, serosal side) produced a small depolarization of Vcs and reduced the hyperpolarization upon lowering [Na+]s, without affecting the decrease in fRa. The effects of mucosal TEA+ and serosal ouabain were additive. Neither amiloride (10(-5) or 10(-3) M) nor tetrodotoxin (10(-6) M) had any effects on Vcs or fRa or on their responses to lowering [Na+]s, suggesting that basolateral Na+ channels do not contribute to the control membrane voltage or to the hyperpolarization upon lowering [Na+]s. The basolateral membrane depolarization upon elevating [K+]s was increased transiently during the hyperpolarization of Vcs upon lowering [Na+]s. Since cable analysis experiments show that basolateral membrane resistance increased, a decrease in basolateral Cl- conductance (gCl-) is the main cause of the increased K+ selectivity. Lowering [Na+]s increases intracellular free [Ca2+], which may be responsible for the increase in the apical membrane TEA(+)-sensitive gK+. We conclude that the decrease in fRa by lowering [Na+]s is mainly caused by an increase in intracellular free [Ca2+], which activates TEA(+)-sensitive maxi K+ channels at the apical membrane and decreases apical membrane resistance. The hyperpolarization of Vcs is due to increase in: (a) apical membrane gK+, (b) the contribution of the Na+ pump to Vcs, (c) basolateral membrane K+ selectivity (decreased gCl-), and (d) intraepithelial current flow brought about by a paracellular diffusion potential. PMID:1613485

Altenberg, G A; Stoddard, J S; Reuss, L

1992-02-01

185

Raman spectroscopic study of synthesized Na-bearing majoritic garnets  

NASA Astrophysics Data System (ADS)

Majoritic garnets in diamond have been considered as the sample from mantle transition zone (e.g. Moore and Gurney, 1985). For non-destructive, in-situ Raman analysis, Gillet et al. (2002) systematically checked chemistry and Raman peak of various majoritic garnets in diamond. They treated majoritic component as number of excess-silica than 3.0 per formula unit. However, in the basaltic system, majorite garnets also have significant amounts of Na. Na substitution is coupled with Si and Ti as follows; Na +Ti = Ca +Al (Ringwood and Lovering, 1970), Na +Si = Ca + Al (Sobolev and Labrentav, 1971; Ringwood and Major, 1971) or Na + Si = Mg + Al (Gasparik, 1989). Each component in garnet is defined as follows; Mj (majorite) component = ((Si-3)-Na)/2), NaSi (Na2MSi5O12 where M= Ca, Mg, Fe2+) component = (Na-T)/2, and NaTi component = Ti/2. Okamoto and Maruyama (2003) conducted UHP experiments in the MORB + H2O system (KNCFMATSH) at 10-19 GPa. They show that 1) Mj and NaTi component are constant and lower than 0.1 at T = 900 \\deg C, and 2) NaSi component increases drastically above 15 GPa although it is neglibly small at P<15 GPa. Raman spectra was newly analyzed using Okamoto and Maruyama (2003)'s run charges. Above 15 GPa, there is a characteristic sharp peak at 910 cm-1 and broad shoulder between 800 and 900 cm-1 as well as broad band near 960 cm-1. Gillet et at (2002) concluded that the former peak at 910cm-1 is the only reliable signature for the majoritic garnet (Si>3). They also implied that the latter two broad peaks are diagnostic feature for Ti rich garnet (> 1wt% of TiO2) as well as peak at 1030 cm-1. However, in all P range (10-19 GPa) of the present study, TiO2 is higher than 1wt%, and there is a peak at 1030 cm-1. Additional Ti-free experiment at 16 GPa, 1200 \\deg C clearly revealed that Na-bearing majoritic garnet has a significant shoulder at 800-900 cm-1. Ref; Gasparik (1989) CMP, 102,389, Gillet et al. (2002) Am.Min., 87, 312, Moore and Gurney (1985)Nature, 318, 553, Okamoto and Maruyama (2003)PEPI, in press, Ringwood and Lovering (1970) EPSL, 7, 371, Ringwood and Major (1971)EPSL, 12, 411, Sobolev and Labrentav (1971)CMP, 31, 1.

Okamoto, K.

2003-12-01

186

Effects of dietary Pi on the renal Na+-dependent Pi transporter NaPi-2 in thyroparathyroidectomized rats.  

PubMed Central

Dietary Pi and parathyroid hormone (PTH) are two most important physiological and pathophysiological regulators of Pi re-absorption in the renal proximal tubule. Effects of dietary Pi on Na+/Pi co-transporter NaPi-2 were investigated in thyroparathyroidectomized (TPTX) rats. NaPi-2 protein and mRNA in the kidney cortex of TPTX rats were increased approximately 3.8- and 2.4-fold in amount respectively compared with those in the sham-operated animals. Administration of PTH to the TPTX rats resulted in a decrease in the amount of NaPi-2 protein, but not in the abundance of NaPi-2 mRNA. Deprivation of dietary Pi in the TPTX rats did not affect the amount of NaPi-2 mRNA and protein. In the Pi-deprived TPTX rats, feeding of a high-Pi diet resulted in marked decreases in Pi transport activity and the amount of NaPi-2 protein in the superficial nephrons. Immunohistochemical analysis demonstrated that administration of PTH to TPTX rats resulted in a decrease in NaPi-2 immunoreactivity from both superficial and juxtamedullary nephrons within 4 h. Switching TPTX animals from a low-Pi diet to the high-Pi diet decreased NaPi-2 immunoreactivity from superficial nephrons, but not from juxtamedullary nephrons, within 4 h. These results suggest that dietary Pi could regulate the amount of NaPi-2 protein in the superficial nephrons in a PTH-independent manner.

Takahashi, F; Morita, K; Katai, K; Segawa, H; Fujioka, A; Kouda, T; Tatsumi, S; Nii, T; Taketani, Y; Haga, H; Hisano, S; Fukui, Y; Miyamoto, K I; Takeda, E

1998-01-01

187

Activation of the Na+, K(+)-ATPase in Narcine brasiliensis.  

PubMed Central

The in vivo activation and turnover rates of the sodium pump (Na+, K(+)-ATPase) were investigated in the electrocytes of the electric organ of the elasmobranch Narcine brasiliensis. The Narcine electric organ appears to be an excellent model for the study of sodium pump activation in an excitable tissue. The sodium transmembrane gradient and high-energy phosphagens were concurrently measured by 23Na and 31P NMR spectroscopy. The resting electric organ, which depends primarily on anaerobic metabolism, displays a high concentration of phosphocreatine (PCr). It has an intracellular sodium concentration ([Na+]i) of 20 +/- 10 milliequivalents/liter as estimated by NMR. Electrical stimulation of the nerves innervating the electric organ results in an increase in [Na+]i in the electrolyte and rapid depletion of PCr. Ouabain causes an 85% decrease in utilization of high-energy phosphagens, indicating that rapid PCr turnover in this tissue is mainly due to Na+, K(+)-ATPase activity. From these data we can determine that the rate of sodium pump turnover increases by greater than 3 orders of magnitude within several hundred milliseconds. In excised unstimulated electric organ slices, changes in [Na+]i equivalent to those occurring with stimulation, but induced by hyperosmolar conditions, do not result in increased PCr hydrolysis. We conclude that cholinergic stimulation of the electric organ causes a rapid and extremely large increase in sodium pump turnover, which is regulated predominantly by factors other than [Na+]i. Images

Blum, H; Nioka, S; Johnson, R G

1990-01-01

188

Rigidification of the autolysis loop enhances Na+ binding to thrombin  

PubMed Central

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

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

2011-01-01

189

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

PubMed Central

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

Lu, Chin-Chih; Hilgemann, Donald W.

1999-01-01

190

NaXe potentials from interference structures in optical collisions  

NASA Astrophysics Data System (ADS)

Experimental differential cross sections for the optical collision process Na(3 s)2S + Xe + h? ? Na(3 p)2P + Xe are presented. By comparison with the results of accurate quantum calculations, the observed oscillatory structure is used to investigate the X2? and B2? potential curves of the NaXe van der Waals molecule. The repulsive branches of both curves are probed in addition to the binding minimum of the ground state. A value of 92 cm-1 is obtained for the dissociation energy.

Hoffmann, O.; Grosser, J.; Rebentrost, F.

2011-09-01

191

New glass-ceramic sealants for Na\\/S battery  

Microsoft Academic Search

The sodium sulfur (Na\\/S) battery is one of the most promising candidates for energy storage applications developed since the\\u000a 1980s. However, the seal between the alpha-alumina and beta-alumina in the Na\\/S battery presents a challenge. In this work,\\u000a the new glass-ceramic sealants for the Na\\/S battery have been developed. The borosilicate glass was chosen as the basic glass\\u000a and TiO2

Shufeng Song; Zhaoyin Wen; Yu Liu; Jiu Lin; Xiaogang Xu; Qunxi Zhang

2010-01-01

192

Influence of NaCl and NaNO3 on sinigrin hydrolysis by foodborne bacteria.  

PubMed

The glucosinolate sinigrin (SNG) is converted by endogenous plant myrosinase or by bacterial myrosinase-like activity to form the potent antimicrobial allyl isothiocyanate. In order to use SNG as a natural antimicrobial precursor in food, it became important to better understand the ability of bacteria to synthesize the enzyme(s) and understand factors influencing this synthesis at a constant SNG concentration. Eight spoilage, pathogenic, or starter culture bacteria were grown separately in medium containing individual or combined salts with SNG. SNG degradation by the bacteria and the formation of its major degradation product, allyl isothiocyanate, were followed for 12 days at 30 or 35°C. The bacterial strains varied in their ability to metabolize SNG, and this was enhanced by NaCl and/or NaNO(3). SNG hydrolysis took place after 4 days, and the greatest amount occurred by day 12. At 12 days, Escherichia coli O157:H7 showed the greatest capacity to hydrolyze SNG (45.3% degradation), followed by Staphylococcus carnosus (44.57%), while Pseudomonas fluorescens was not active against SNG. The ability of tested strains to metabolize SNG, in decreasing order, was as follows: Escherichia coli O157:H7 > Staphylococcus carnosus > Staphylococcus aureus > Pediococcus pentosaceus > Salmonella Typhimurium > Listeria monocytogenes > Enterococcus faecalis > Pseudomonas fluorescens. PMID:22186059

Herzallah, S; Lledó, M Lara; Holley, R

2011-12-01

193

Characterization of Na-X, NaA, and coal fly ash zeolites and their amorphous precursors by IR, MAS NMR and XPS  

Microsoft Academic Search

By fusion with sodium hydroxide followed by a hydrothermal reaction, fly ash and Alenriched fly ash were converted into Na-X and Na-A zeolites, respectively. The authentic Na-X, Na-A and fly ash zeolites as well as their amorphous precursors have been characterized by IR, 29Si and 27Al MAS NMR, XPS\\/AES, TG, and comparative ion-exchange studies of Cs and K with Na

N. Shigemoto; S. Sugiyama; H. Hayashi; K. Miyaura

1995-01-01

194

Processing of NaBH 4 from NaBO 2 with MgH 2 by ball milling and usage as hydrogen carrier  

Microsoft Academic Search

In this paper, NaBH4 is synthesized from NaBO2 and MgH2 under inert gas via ball milling, without applying high temperature or pressure. Developments in the recycling of NaBO2 will make NaBH4 usage more feasible. To obtain the optimum recycling conditions of NaBO2 with MgH2 via solid phase reaction under inert atmosphere, 3 sets of experiments were performed. With additives such

Çetin Çakany?ld?r?m; Metin Gürü

2010-01-01

195

Structure and superconductivity in YBa 2Cu 3O y with additives of NaNO 3 and NaCl  

Microsoft Academic Search

YBa2Cu3Oy (YBCO) cuprates with the additives of NaNO3 and NaCl were synthesized by the standard solid-state reaction technique. For the samples with addition of NaNO3, the superconducting transition temperature Tc0 remains almost unchanged although the lattice constants of the unit cell decrease monotonically with an increase in the additive of NaNO3. The superconducting transition temperature Tc0 for NaCl doping in

X. S Wu; F. Z Wang; S. Nie; J. S Liu; L. Yang; S. S. Jiang

2000-01-01

196

Regulation of the Basolateral Na(+), K(+)-ATPase in the Activation of Electrogenic Na(+) Absorption Induced by Isoproterenol in the Rat Distal Colon.  

PubMed

We investigated the effects of cAMP on the basolateral Na(+), K(+)-ATPase and apical amiloride-sensitive Na(+) channel in the rat distal colon. Under mucosal treatment with nystatin, isoproterenol and forskolin increased the basolateral Na(+) pump current. Under serosal treatment with ouabain, both agents slightly increased the amiloride-sensitive Na current, but not to a significant level. We concluded that cAMP activates the basolateral Na(+), K(+)-ATPase in the rat distal colon. PMID:24018672

Tsuchiya, Yo; Suzuki, Yuichi

2013-09-07

197

Establishment of stable NaCl-resistant rice plant lines from anther culture: distribution pattern of K+\\/Na+ in callus and plant cells  

Microsoft Academic Search

Soil salinity markedly suppresses the growth of rice (Oryza sativa L.). We established rice anther culture to select for rice callus lines adapted to NaCl stress and regenerated plant progenies\\u000a resistant to a NaCl stress of E.C. 16–18?mS. When exposed to NaCl, NaCl-adapted rice calli lost K+ and accumulated little Na+. Conversely, plant cells lost relatively little K+ and accumulated

P. Sathish; O. L. Gamborg; M. W. Nabors

1997-01-01

198

K+-induced natriuresis is preserved during Na+ depletion and accompanied by inhibition of the Na+-Cl- cotransporter.  

PubMed

During hypovolemia and hyperkalemia, the kidneys defend homeostasis by Na(+) retention and K(+) secretion, respectively. Aldosterone mediates both effects, but it is unclear how the same hormone can evoke such different responses. To address this, we mimicked hypovolemia and hyperkalemia in four groups of rats with a control diet, low-Na(+) diet, high-K(+) diet, or combined diet. The low-Na(+) and combined diets increased plasma and kidney ANG II. The low-Na(+) and high-K(+) diets increased plasma aldosterone to a similar degree (3-fold), whereas the combined diet increased aldosterone to a greater extent (10-fold). Despite similar Na(+) intake and higher aldosterone, the high-K(+) and combined diets caused a greater natriuresis than the control and low-Na(+) diets, respectively (P < 0.001 for both). This K(+)-induced natriuresis was accompanied by a decreased abundance but not phosphorylation of the Na(+)-Cl(-) cotransporter (NCC). In contrast, the epithelial Na(+) channel (ENaC) increased in parallel with aldosterone, showing the highest expression with the combined diet. The high-K(+) and combined diets also increased WNK4 but decreased Nedd4-2 in the kidney. Total and phosphorylated Ste-20-related kinase were also increased but were retained in the cytoplasm of distal convoluted tubule cells. In summary, high dietary K(+) overrides the effects of ANG II and aldosterone on NCC to deliver sufficient Na(+) to ENaC for K(+) secretion. K(+) may inhibit NCC through WNK4 and help activate ENaC through Nedd4-2. PMID:23986520

van der Lubbe, Nils; Moes, Arthur D; Rosenbaek, Lena L; Schoep, Sharon; Meima, Marcel E; Danser, Alexander H J; Fenton, Robert A; Zietse, Robert; Hoorn, Ewout J

2013-08-28

199

A study of the reaction between NaHCO3 and H: Apparent closure on the chemistry of mesospheric Na  

Microsoft Academic Search

The reaction between sodium bicarbonate (NaHCO3) and atomic H is the only likely route (apart possibly from daytime photolysis) for recycling this major sodium reservoir back to atomic Na in the upper mesosphere. The rate coefficient was determined for the first time by reacting NaHCO3 in a known excess of H in a fast flow tube, yielding k(227K)=(1.7+\\/-0.6)×10-13 and k(307K)=(5.2+\\/-2.5)×10-13cm-3molecule-1s-1.

Rachel M. Cox; Daniel E. Self; John M. C. Plane

2001-01-01

200

On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination  

SciTech Connect

Photoelectron spectroscopy was combined with ab initio calculations to elucidate the structure and bonding in Si62- and NaSi6-. Well-resolved electronic transitions were observed in the photoelectron spectra of Si6- and NaSi6- at three photon energies (355, 266, and 193 nm). The spectra of NaSi6- were observed to be similar to those of Si6- except that the electron binding energies of the former are lower, suggesting that the Si6 motif in NaSi6- is structurally and electronically similar to that of Si6-. The electron affinity of Si6 and NaSi6 were measured fairly accurately to be 2.23 ± 0.03 eV and 1.80 ± 0.05 eV, respectively. Global minimum structure searches for Si62- and NaSi6- were performed using Gradient Embedded Genetic Algorithm followed by B3LYP, MP2 and CCSD(T) calculations. Vertical electron detachment energies (VDEs) were calculated for the lowest Si6- and NaSi6- structures at the CCSD(T)/6-311+G(2df), ROVGF/6-311+G(2df), UOVGF/6-311+G(2d), TD B3LYP/6-311+G(2df) levels of theory. Experimental VDEs were used to verify the global minimum structure for NaSi6-. Though the octahedral Si62-, analogous to the closo-form of borane B6H62-, is the most stable form for the bare hexa-silicon dianion, it is not the kernel for the NaSi6- global minimum. The most stable isomer of NaSi6- is based on a Si62- motif, which is distorted into C2v symmetry similar to the ground state structure of Si6-. The octahedral Si62- coordinated by a Na+ is a low-lying isomer and was also observed experimentally. The chemical bonding in Si62- and NaSi6- was understood using NBO, molecular orbital, and ELF analysis.

Zubarev, Dmitry Y.; Alexandrova, Anastassia N.; Boldyrev, Alexander I.; Cui, Lifeng; Li, Xi; Wang, Lai S.

2006-03-23

201

Resonant collisional dissociation of Na[sub 2][sup +] by Na(3[ital p]) in an effusive beam  

SciTech Connect

We observe the production of Na[sup +] ions in a single effusive sodium atomic beam via intrabeam dissociating collisions of laser-excited Na(3[ital p]) atoms with Na[sub 2][sup +] ions created by associative ionization. The rather large cross section for this collisional dissociation process has been experimentally determined to be 3([plus minus]1)[times]10[sup [minus]13] cm[sup 2] at a source temperature of [approx]530 K. A classical Langevin model gives an estimate based on long-range forces of about twice this value.

Tapalian, C.; Smith, W.W. (Physics Department, University of Connecticut, Storrs, Connecticut 06269 (United States))

1994-02-01

202

Control of presynaptic function by a persistent Na+ current  

PubMed Central

Little is known about ion channels that regulate the graded, subthreshold properties of nerve terminals. Using the calyx of Held, we demonstrate here a large presynaptic persistent Na+ current with unusually hyperpolarized activation voltage. This feature allowed the current to determine both the resting potential and resting conductance of the nerve terminal. Calyces express presynaptic glycine receptors whose activation depolarizes the synapse. We found that activation of the persistent Na+ current was an essential component in the response to glycine. This Na+ current originated at or very close to the terminal, and was sustained even after trains of large spike-like depolarizations. Because Na+ channels also underlie the presynaptic action potential, we conclude that their action both triggers and modulates exocytosis through control of presynaptic membrane voltage.

Huang, Hai; Trussell, Laurence O.

2009-01-01

203

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

204

NASICON-related Na?.?Mn?.?Fe?.?(PO?)?.  

PubMed

The solid solution, sodium [iron(III)/manganese(II)] tris-(orthophosphate), Na?.?Mn?.?Fe?.?(PO?)?, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)?(PO?)?] framework is built up from an (Mn/Fe)O?octa-hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO? tetra-hedron (site symmetry .2). The Na? cations are distributed over two partially occupied sites in the cavities of the framework. One Na? cation (site symmetry -3.) is surrounded by six O atoms, whereas the other Na? cation (site symmetry .2) is surrounded by eight O atoms. PMID:22807697

Yatskin, Michael M; Strutynska, Nataliya Yu; Baumer, Vyacheslav N; Ogorodnyk, Ivan V; Slobodyanik, Nikolay S

2012-06-23

205

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

206

Sinopse dos marcos em matéria de segurança alimentar na ...  

Center for Food Safety and Applied Nutrition (CFSAN)

... 1995 Seafood Hazard Analysis Critical Control Point (Ponto de controle crítico para análise de risco em frutos do mar, HACCP na sigla em inglês ... More results from www.fda.gov/food/guidanceregulation/fsma

207

Identification of new polymorphic microsatellite markers in the NA1 ...  

Treesearch

Due to the limited intralineage genetic variation, only a few polymorphic markers ... for use in studies involving the epidemiology and evolution of P. ramorum. ... NA2 lineage, demonstrating the power and flexibility of the screening technique.

208

Oxidation of reduced platinum clusters in Pt-NaY  

SciTech Connect

Raman spectroscopy and [sup 129]Xe NMR, in conjunction with hydrogen chemisorption and transmission electron microscopy, have been used to monitor the location and stability of metal clusters as a function of oxidation condition for NaY-zeolite-supported platinum. After initial calcination and reduction of Pt-NaY, subsequent reoxidation at temperatures up to 873 K induces no additional agglomeration of the metal species. Different Pt-NaY systems exhibit cluster-size-dependent responses to reoxidation treatment, consistent with the greater reactivities expected for small metal particles compared to larger aggregates. The authors present a summary of platinum dispersal chemistry in NaY zeolite based on these and recent corroborative results. 69 refs., 18 figs., 1 tab.

Chmelka, B.F. (Univ. of California, Santa Barbara, CA (United States) Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., Berkeley, CA (United States)); Went, G.T. (Curagen Corp., Branford, CT (United States)); Csencsits, R. (Argonne National Lab., IL (United States)); Petersen, E.E.; Bell, A.T.; Radke, C.J. (Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States))

1993-12-01

209

Silver, zinc, and copper exchange in a Na-clinoptilolite and resulting effect on antibacterial activity  

Microsoft Academic Search

Ag+–Na+, Zn2+–Na+, and Cu2+–Na+ equilibria for clinoptilolite-rich mineral from Gördes (Western Anatolia) were investigated at 25 °C and 0.1 N total solution normality. While silver exchange was favorable over the whole concentration range, zinc and copper were partially exchanged and preferred only at low concentrations. The standard free energies of exchanges for Ag+–Na+, Zn2+–Na+, and Cu2+–Na+ pairs were found as

Ayben Top; Semra Ülkü

2004-01-01

210

Na-Ca-Cl relations in basinal fluids  

SciTech Connect

A new mathematical transformation of Na, Ca, and Cl concentrations in numerous basinal fluids around the world produces a linear slope of unity between the milliequivalencies of Na and Ca cations. The transformation entails a simple milliequivalent comparison between the excess Ca and the Na deficit relative to seawater reference ratios. The relevant parameters are: Ca{sub excess} = [Ca{sub meas} - (Ca/Cl){sub SW}Cl{sub meas}] 2/40.08, Na{sub deficit} = [(Na/Cl){sub SW} Cl{sub meas} - Na{sub meas}] 1/22.99, where the concentrations (in mg/L) of the ions measured (meas) in a sample are referred to those in seawater (sw), and the numerical constants convert the results to meq/L. For >800 samples from numerous fluid reservoirs, with Cl concentrations that range from approximately 1-300 g/L and host lithologies from carbonates to granites, a highly correlated regression termed the Basinal Fluid Line (BFL) is found: Ca{sub excess} = 0.967 (Na{sub deficit}) + 140.3 R = 0.981. The unit slope of the BFL indicates a net cation exchange ratio of 2 Na for 1 Ca. The excess-deficit parameters show no correlation to Mg or K. If a single predominating reaction is presumed to control the BFL, only albitization of plagioclase by 2 Na for 1 Ca exchange is plausible. The BFL offers no support for a predominating reaction involving the 1:1 exchange of Na for Ca that has also been proposed for albitization reactions, nor for the hypothesis that dolomitization produces the elevated Ca contents of basinal fluids. The BFL may incorporate the effects of other water-rock reactions provided that they involve a net exchange of 2 Na for 1 Ca in sedimentary basins. The small y-intercept of 140.3 of the BFL is generally consistent with an origination of the brines from seawater, which would plot at the origin of an excess-deficit graph. 64 refs., 5 figs.

Davisson, M.L. [Lawrence Berkeley National Lab., CA (United States); Criss, R.E. [Washington Univ., St. Louis, MO (United States)

1996-08-01

211

An empirical NaKCa geothermometer for natural waters  

USGS Publications Warehouse

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

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

1973-01-01

212

Growth and Characterization of Na-doped KFeAs  

NASA Astrophysics Data System (ADS)

We grew mulitple dopings of Na-doped KFeAs, with a goal of observing an upward shift in the Tc from the KFeAs parent compound and a sharpening of the transistion phase curve. Using a VSM and PPMS to charecterize the magnetic transport, resistivity, and heat capacity, we have come to a conclusion on the sucess of Na-doping into the KFeAs family of FeAs superconductors.

Sims, Zachary; Tan, Guotai; Carr, Scott; Zhang, Chenglin; Dai, Pengcheng

2013-03-01

213

CuCl Nanocrystals in Monocrystalline NaCl Matrix  

Microsoft Academic Search

It is demonstrated that the growth of CuC1 crystals in a single crystal of NaC1 can be realized by the doping of the melted NaCl solution with copper. The absorption spectra in ambient exhibit peaks allotted to the excitonic transitions with a displacement towards great energies. The mean size of the crystallites is approximately 20 Å. From absorption spectra analysis,

M. Samah; S. Mahtout; M. Bouguerra; M. A. Belkhir

2004-01-01

214

Na + \\/H + exchange mediates postprandial ileal water and electrolyte transport  

Microsoft Academic Search

Feeding stimulates fluid and electrolyte absorption in the small intestine. Previous studies have suggested that Na+\\/glucose cotransport is important in initiating this response in the jejunum. The purpose of this study was to determine whether Na+\\/H+ exchange plays a role in meal-induced absorption. Exteriorized, neurovascularly intact jejunal and ileal loops (25 cm) were constructed in dogs. Following a two-week period

Oscar J. Hines; Anton J. Bilchik; David W. Mcfadden; Paula J. Rodgers; Norman Bautista; Michael J. Zinner; Stanley W. Ashley

1995-01-01

215

Regulation of the Na +\\/K + ATPase by Klotho  

Microsoft Academic Search

Klotho-hypomorphic (Klothohm) mice suffer from renal salt wasting and hypovolemia despite hyperaldosteronism. The present study explored the effect of Klotho on renal Na+\\/K+ ATPase activity. According to immunohistochemistry and confocal microscopy Na+\\/K+ ATPase protein abundance in isolated collecting ducts was lower in Klothohm mice than in their wild type littermates (Klotho+\\/+). Analysis with dual electrode voltage clamp recording showed that

Mentor Sopjani; Ioana Alesutan; Miribane Dërmaku-Sopjani; Shuchen Gu; Christine Zelenak; Carlos Munoz; Ana Velic; Michael Föller; Kevin P. Rosenblatt; Makoto Kuro-o; Florian Lang

2011-01-01

216

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

217

Metal Fluoride Complexes of Na,K-ATPase  

PubMed Central

The Na,K-ATPase belongs to the P-type ATPase family of primary active cation pumps. Metal fluorides like magnesium-, beryllium-, and aluminum fluoride act as phosphate analogues and inhibit P-type ATPases by interacting with the phosphorylation site, stabilizing conformations that are analogous to specific phosphoenzyme intermediates. Cardiotonic steroids like ouabain used in the treatment of congestive heart failure and arrhythmias specifically inhibit the Na,K-ATPase, and the detailed structure of the highly conserved binding site has recently been described by the crystal structure of the shark Na,K-ATPase in a state analogous to E2·2K+·Pi with ouabain bound with apparently low affinity (1). In the present work inhibition, and subsequent reactivation by high Na+, after treatment of shark Na,K-ATPase with various metal fluorides are characterized. Half-maximal inhibition of Na,K-ATPase activity by metal fluorides is in the micromolar range. The binding of cardiotonic steroids to the metal fluoride-stabilized enzyme forms was investigated using the fluorescent ouabain derivative 9-anthroyl ouabain and compared with binding to phosphorylated enzyme. The fastest binding was to the Be-fluoride stabilized enzyme suggesting a preformed ouabain binding cavity, in accord with results for Ca-ATPase where Be-fluoride stabilizes the E2-P ground state with an open luminal ion access pathway, which in Na,K-ATPase could be a passage for ouabain. The Be-fluoride stabilized enzyme conformation closely resembles the E2-P ground state according to proteinase K cleavage. Ouabain, but not its aglycone ouabagenin, prevented reactivation of this metal fluoride form by high Na+ demonstrating the pivotal role of the sugar moiety in closing the extracellular cation pathway.

Cornelius, Flemming; Mahmmoud, Yasser A.; Toyoshima, Chikashi

2011-01-01

218

Thermodynamics of NaOH(aq) in hydrothermal solutions  

Microsoft Academic Search

Apparent molar volumes and osmotic coefficients of NaOH solutions, calculated from critically evaluated literature data on volumes and vapor pressures, were used to fit the Pitzer equations to yield ion-interaction parameters as a function of temperature and pressure. These parameters allow the calculation of osmotic and activity coefficients from 0-350°C, saturation pressure to about 400 bars and 0-10 molal NaOH,

Roberto T. Pabalan; Kenneth S. Pitzer

1987-01-01

219

Thermodynamics of NaOH(aq) in hydrothermal solutions  

Microsoft Academic Search

Apparent molar volumes and osmotic coefficients of NaOH solutions, calculated from critically evaluated literature data on volumes and vapor pressures, were used to fit the Pitzer equations to yield ion-interaction parameters as a function of temperature and pressure. These parameters allow the calculation of osmotic activity coefficients from 0-350°C, saturation pressure to about 400 bars and 0-10 molal NaOH, and

R. T. Pabalan; K. S. Pitzer

1987-01-01

220

Kinetic characterization of Na,K-ATPase inhibition by Eosin.  

PubMed

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 (3 mM) the eosin IC(50) for Na pump inhibition was 19 microM. 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 microM FITC. With increasing eosin concentrations (0.1 microM-10 microM) 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 5 mM pNPP the eosin IC(50) for Na pump inhibition was 3.8+/-0.23 microM. 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 C(12)E(8) (0.1%) but the inhibition of ATPase remained mixed. PMID:17331759

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

2007-02-28

221

Reverse energy pooling in a K-Na mixture  

SciTech Connect

We report experimental rate coefficients for the reverse heteronuclear energy-pooling collisions K(5D)+Na(3S){r_arrow}K(4P)+Na(3P) and K(7S)+Na(3S){r_arrow}K(4P)+Na(3P) at thermal energies. Both reactions are exothermic and very high rates were observed showing that reverse exothermic energy-pooling is an order of magnitude more efficient than the corresponding forward endothermic energy-pooling reactions. This is in accordance with the general behavior of the exothermic and endothermic energy-pooling rate coefficients in alkali-metal atoms. In the experiment the potassium atoms were excited in two steps to either the 5D or 7S state via the 4P level using two broadband cw dye lasers. A double-modulation technique has been used to select the fluorescence contributions at the Na(3P{sub J}) exit channels due only to the above reactions. The ground-state sodium and potassium atom densities were measured by the absorption of lines from a K-Na hollow-cathode lamp. The measured densities and fluorescence intensities have been used to obtain absolute reverse energy-pooling rate coefficients. The contribution to the rate coefficients from other processes are discussed. {copyright} {ital 1998} {ital The American Physical Society}

De Filippo, G.; Guldberg-Kjaer, S.; Milosevic, S.; Pedersen, J.O. [Niels Bohr Institute, O/rsted Laboratory, Universitetsparken 5, DK-2100 Copenhagen O/ (Denmark); Allegrini, M. [Istituto Nazionale per la Fisica della Materia, Dipartimento di Fisica, Universita di Pisa, Piazza Torricelli 2, I-56126, Pisa (Italy)]|[Dipartimento di Fisica della Materia e Tecnologie Fisiche Avanzate, Universita di Messina, Salita Sperone 31, I-98166, SantAgata-Messina (Italy)

1998-01-01

222

Bacterial Na+-translocating ferredoxin:NAD+ oxidoreductase.  

PubMed

The anaerobic acetogenic bacterium Acetobacterium woodii carries out a unique type of Na(+)-motive, anaerobic respiration with caffeate as electron acceptor, termed "caffeate respiration." Central, and so far the only identified membrane-bound reaction in this respiration pathway, is a ferredoxin:NAD(+) oxidoreductase (Fno) activity. Here we show that inverted membrane vesicles of A. woodii couple electron transfer from reduced ferredoxin to NAD(+) with the transport of Na(+) from the outside into the lumen of the vesicles. Na(+) transport was electrogenic, and accumulation was inhibited by sodium ionophores but not protonophores, demonstrating a direct coupling of Fno activity to Na(+) transport. Results from inhibitor studies are consistent with the hypothesis that Fno activity coupled to Na(+) translocation is catalyzed by the Rnf complex, a membrane-bound, iron-sulfur and flavin-containing electron transport complex encoded by many bacterial and some archaeal genomes. Fno is a unique type of primary Na(+) pump and represents an early evolutionary mechanism of energy conservation that expands the redox range known to support life. In addition, it explains the lifestyle of many anaerobic bacteria and gives a mechanistic explanation for the enigma of the energetic driving force for the endergonic reduction of ferredoxin with NADH plus H(+) as reductant in a number of aerobic bacteria. PMID:20921383

Biegel, Eva; Müller, Volker

2010-10-04

223

23Na and (1)H NMR microimaging of intact plants.  

PubMed

(23)Na 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 (23)Na as well as (1)H NMR microimaging. Experiments were performed at 11.75 T with a double resonant (23)Na-(1)H probehead. The probehead was homebuilt and equipped with a climate chamber. T(1) and T(2) of (23)Na were measured in the cross section of the hypocotyl. Within 85 min (23)Na images with an in-plane resolution of 156 x 156 micrometer 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, (23)Na 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. PMID:10828197

Olt, S; Krötz, E; Komor, E; Rokitta, M; Haase, A

2000-06-01

224

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

2012-05-24

225

Chemicobiological effects of herbicide MCPA-Na on plasma proteins.  

PubMed

Under physiological conditions, the potential hematological toxicity of herbicide 2-methyl-4-chlorophenoxyacetic acid sodium (MCPA-Na) was discussed by fluorescence probe technology and spectroscopy methods including three-dimensional (3D) fluorescence, UV absorption and circular dichroism (CD) spectra. In vitro, MCPA-Na bound with bovine serum albumin (BSA) and formed new complex at ground state by electrostatic force and hydrogen bond. During the process, non-radiation energy transfer from BSA to MCPA-Na occurred and the distance r between donor and acceptor was obtained based on Förster theory. The binding site was investigated by fluorescence probe method and the results implied MCPA-Na was absorbed on domain II of BSA molecule. The enthalpy change (?H(?)), Gibbs free energy change (?G(?)) and entropy change (?S(?)) were calculated at four different temperatures according to Van't Hoff isobar equation and Gibbs-Helmholtz equation. Negative value of ?G(?) indicated the process of binding was a spontaneous and irreversible process, which gave a broad hint that MCPA-Na was likely to be poisonous. CD spectra exhibited significant changes of secondary structures in BSA molecule and three-dimensional fluorescence spectra indicated the tryptophan residue in BSA was placed in a less hydrophobic environment, which presented additional evidence to caution the danger of MCPA-Na residue in food. Meanwhile, the mechanism and geometry of the binding was analyzed at molecular level. PMID:21670962

Zhang, Hua-xin; Liu, Lin

2011-06-14

226

Voltage dependence of Na-Ca exchanger conformational currents.  

PubMed Central

Properties of a transient current (Icont) believed to reflect a conformational change of the Na-Ca exchanger molecules after Ca2+ binding were investigated. Intracellular Ca2+ concentration jumps in isolated cardiac myocytes were generated with flash photolysis of caged Ca2+ dimethoxynitrophenamine, and membrane currents were simultaneously measured using the whole-cell variant of the patch-clamp technique. A previously unresolved shallow voltage dependence of Icont was revealed after developing an experimental protocol designed to compensate for the photoconsumption of the caged compound. This voltage dependence can be interpreted to reflect the distribution of Na-Ca exchanger conformational states with the Ca2+ binding site exposed to the inside of the cell immediately before the flash. Analysis performed by fitting a Boltzmann distribution to the observed data suggests that under control conditions most exchanger molecules reside in states with the Ca2+ binding site facing the outside of the cell. Dialysis of the cytosol with 3',4'-dichlorobenzamil, an organic inhibitor of the Na-Ca exchange, increased the magnitude of Icont and changed the voltage dependence, consistent with a parallel shift of the charge/voltage curve. This shift may result from intracellular DCB interfering with an Na(+)-binding or Na(+)-translocating step. These observations are consistent with Icont arising from a charge movement mediated by the Na-Ca exchanger molecules after binding of Ca2+.

Niggli, E; Lipp, P

1994-01-01

227

A Complete Basis Set Estimate of Cation-p Bond Strengths: Na+(ethylene) and Na+(benzene)  

SciTech Connect

Large scale second order perturbation theory and couple cluster theory calculations were performed on the Na+(ethylene) and Na+(benzene) complexes in an effort to estimate binding enthalpies in the complete basis set limit. The resulting best estimates are DH0[Na+(ethylene)] = -13.7 ? 0.2 kcal/mol and DH0[Na+(benzene)] = -23.9 ? 0.3 kcal/mol, which include small corrections for core/valence correlation effects. The former value can be compared to a measurement of -10.3 ? 1.0 kcal/mol obtained from collision induced dissociation, while the latter value is approximately midway between the two existing experimental values which differed by 6.5 kcal/mol. For the basis sets considered in this study, the counterpoise-corrected binding energies were found to be in much worse agreement with the complete basis set limit than the raw values.

Feller, David F.

2000-06-02

228

Na*(3 p)-Formation under grazing scattering of Na+-ions at an Al(111) surface  

NASA Astrophysics Data System (ADS)

Excited Na*(3 p)-atoms are observed in grazing surface-collision experiments with Na+-beams. Such atoms can be formed beyond a certain threshold velocity via resonant electron transfer between atomic and metallic conduction band levels due to motion of the atom relative to the surface of the metal (“kinematic resonance”). This mechanism is studied here theoretically employing two different techniques: the nonperturbative “Coupled Angular Mode” (CAM) method and the approximate “Transfer Hamiltonian” (TH) method. The calculated Na*(3 p)-populations agree well with recent experimental results. Moreover, the complete density matrix of the Na*(3 p)-subspace has been computed with the TH-method for ion-energies between 10 and 300 keV.

Zimny, R.; Borisov, A. G.

1994-06-01

229

The K\\/Na and Ca\\/Na ratios and rapeseed yield, under soil salinity or sodicity  

Microsoft Academic Search

Rapeseed (Brassica napus) is a crop relatively tolerant to salt and sodium. Our objective was to study the interactions between Na, K and Ca and their relationship with its yield under the isolated effects of soil salinity or sodicity.

Claudia A. Porcelli; Flavio H. Gutierrez Boem; Ratil S. Lavado

1995-01-01

230

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

SciTech Connect

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

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

2008-11-28

231

Study on the transformation from NaCl-type Na2TiO3 to layered titanate  

NASA Astrophysics Data System (ADS)

NaCl-type crystal structure sodium titanate (Na2TiO3), which exhibits a unit cell parameter of a=4.49 Å, was obtained by high temperature molten salt reaction. An intermediate phase product with layered structure was prepared by leaching the obtained Na2TiO3. We propose that the layered titanate structure is composed of Na2TiO3 and H2O, corresponding to the host-layer and guest-substance, respectively. Furthermore, the crystal structures of layered titanate were optimized by the density functional theory (DFT). This indicates that water molecules are distributed in an orderly manner in the interlayer through the formation of hydrogen-bonded chain. Moreover, the position of the adjacent lamella translates to c/2 along the c-axis after the intercalation of water.

Liu, Y. H.; Zhao, W.; Wang, W. J.; Yang, X.; Chu, J. L.; Xue, T. Y.; Qi, T.; Wu, J. Y.; Wang, C. R.

2012-03-01

232

A Na\\/beta double prime-alumina\\/NaAlCl4, Cl2\\/C circulating cell  

Microsoft Academic Search

A Na\\/beta double prime-alumina\\/NaAlCl4, Cl2\\/C circulating cell at 200 C has been successfully demonstrated. A circulating system was operated for over two weeks to charge and discharge this cell. This cell can sustain continuous discharge at 9 mA\\/sq cm and an output cell voltage greater than 3.2 V for 42 hours. Linear sweep voltametry was used to characterize the cell

J. Y. Cherng; D. N. Bennion

1986-01-01

233

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

Microsoft Academic Search

NaHTi3O7 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 NaHTi3O7 nanotubes undergo a slight degradation and more degradation of the tubular shape, respectively at 300 and 500 ?C, and finally

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

2007-01-01

234

Ca2+/Na+ exchanger and Na+,K+ 2Cl- cotransporter in lens fiber plasma membrane vesicles.  

PubMed

When the Ca(2+)-sensitive fluorescent probe, Fura-2, or the Na(+)-sensitive probe, SBFI, in their cell permeable forms or the Cl(-)-specific probe, SPQ, were incubated with plasma membrane vesicles prepared from dogfish and bovine lenses fibers, there was a selective accumulation of the ion-specific probes within the vesicles. The SBFI and Fura-2 fluorescent excitation ratios of 340 nm to 380 nm (em: 505 nm) in the presence of an outwardly-directed Na+ gradient across the vesicles membrane, indicate that the influx of Ca2+ is increased by 152.5% and 147.4% for dogfish and bovine vesicles, respectively. The Na+ influx into the vesicles is also enhanced by 154.1% for dogfish and 149.1% for bovine lens when an outwardly-directed Ca2+ was present. This stimulation is not affected when either 50 microM valinomycin, or 50 mM K+ is present. The activity of this bidirectional Ca2+/Na+ exchanger could be inhibited by 100 microM bepridil or 200 microM La3+. The entrance behaviour of Cl- as monitored by the SPQ fluorescent signal indicates that, the Cl- influx is Na(+)-dependent. The Cl- influx is stimulated 152.8% and 187.6% for dogfish and bovine lens, respectively, when an inwardly-directed Na+ gradient is present, and is further enhanced when a K+ gradient is also present. The stoichiometry of Na+ to Cl- entering the vesicles was 1:2. This Na+,K+ 2Cl- cotransporter is not affected by 20 microM valinomycin or 50 mM K+. However, the transporter is completely inhibited by 50 microM furosemide.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1486938

Ye, J J; Zadunaisky, J A

1992-12-01

235

Implosions of NaF plasmas with a 3MA driver for a Na\\/Ne photopumped laser  

Microsoft Academic Search

Summary form only given. Implosions of NaF capillary-discharge plasmas with 3-MA driving current are being investigated to increase the power in this pump line in order to demonstrate lasing. Implosion experiments were carried out on the Double Eagle generator at Physics International. To match the 3-MA driving current of this generator, the mass per unit length of the NaF plasma

F. C. Young; D. D. Hinshelwood; C. Deeney; T. Nash; R. Prasad; M. Kirshnan

1990-01-01

236

Gibbs ensemble Monte Carlo simulation of supercritical CO2 adsorption on NaA and NaX zeolites  

Microsoft Academic Search

Adsorption of supercritical carbon dioxide on two kinds of zeolites with identical chemical composition but different pore structure (NaA and NaX) was studied using the Gibbs ensemble Monte Carlo simulation. The model frameworks for the two zeolites with Si\\/Al ratio being unity have been chosen as the solid structures in the simulation. The adsorption behaviors of supercritical CO2 on the

Shanshan Liu; Xiaoning Yang

2006-01-01

237

Na +–K +ATPase inhibition and depolarization induce glutamate release via reverse Na +-dependent transport in spinal cord white matter  

Microsoft Academic Search

Excitotoxic mechanisms involving ?-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA)\\/kainate receptors play an important role in mediating cellular damage in spinal cord injury. However, the precise cellular mechanisms of glutamate release from non-synaptic white matter are not well understood. We examined how the collapse of transmembrane Na+ and K+ gradients induces reverse operation of Na+-dependent glutamate transporters, leading to glutamate efflux and injury to rat

S Li; P. K Stys

2001-01-01

238

Na?Ca?Cl relations in basinal fluids  

NASA Astrophysics Data System (ADS)

A new mathematical transformation of Na, Ca, and Cl concentrations in numerous basinal fluids around the world produces a linear slope of unity between the mill iequivalencies of Na and Ca cations. The transformation entails a simple milliequivalent comparison between the excess Ca and the Na deficit relative to seawater reference ratios. The relevant parameters are: Caexcess = [ Cameans - ( Ca/Cl) swClmeans] 2/40.08, Nadeficit = [( Na/Cl) swClmeans - Nameans] 1/22.99, where the concentrations (in mg/L) of the ions measured (meas) in a sample are referred to those in seawater (sw), and the numerical constants convert the results to meq/L. For >800 samples from numerous fluid reservoirs, with Cl concentrations that range from approximately 1-300 g/L and host lithologies from carbonates to granites, a highly correlated regression termed the Basinal Fluid Line (BFL) is found: Ca excess = 0.967 (Na deficit) + 140.3 R = 0.981. The unit slope of the BFL indicates a net cation exchange ratio of 2 Na for 1 Ca. The excess-deficit parameters show no correlation to Mg or K. If a single predominating reaction is presumed to control the BFL, only albitization of plagioclase by 2 Na for 1 Ca exchange is plausible. The BFL offers no support for a predominating reaction involving the 1:1 exchange of Na for Ca that has also been proposed for albitization reactions, nor for the hypothesis that dolomitization produces the elevated Ca contents of basinal fluids. The BFL may incorporate the effects of other water-rock reactions provided that they involve a net exchange of 2 Na for 1 Ca in sedimentary basins. The small y-intercept of 140.3 of the BFL is generally consistent with an origination of the brines from seawater, which would plot at the origin of an excess-deficit graph. However, for regressions derived for fluids from individual basins, the y-intercepts increase with increasing salinity of their fluids, consistent with model predictions for dissolution of halite into either a seawater or freshwater parent, followed by 2 Na for 1 Ca exchange. Because the hydrosphere is dominated by seawater and the upper crust by feldspar minerals, the BFL arguably represents the overall product of cation exchange of high salinity fluids in deep continental environments.

Davisson, M. Lee; Criss, Robert E.

239

NaCl Taste Thresholds in 13 Inbred Mouse Strains  

PubMed Central

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

Ishiwatari, Yutaka

2012-01-01

240

(22)Ne(proton, gamma)(23)Na, (23)Na(proton, gamma)(24)Mg, and globular cluster abundance anomalies  

NASA Astrophysics Data System (ADS)

Anticorrelations between sodium and oxygen have been observed in red giant stars in globular clusters, contrary to expectations from the standard theory of stellar evolution. It has been proposed that the 23Na is being produced through the NeNa cycle operating in layers above the main hydrogen-burning shell. The (p, ?) reactions that produce and destroy sodium have large uncertainties because of the possible influence of several resonances. We have carried out measurements of the ( 3He, d) proton-stripping reaction on 22Ne and 23Na in order to study these resonances. The upper limits on the resonance strengths of two possible resonances at Ecm = 68 and 100 keV, that account for most of the uncertainty in 22Ne( p, ?)23Na, have been reduced by factors of 10 and 4, respectively. The reaction rate of 23Na(p, ?) 24Mg has been increased dramatically with the observation of the resonance at Ecm = 136 keV with an increased strength from 10 to 6300 times stronger than the previously used value. The effect of these changes is to establish the nuclear reactions that can produce sodium in the red giant hydrogen-burning shell. The production of sodium is seen to coincide with the destruction of oxygen, through the NeNa and the CNO cycle respectively.

Hale, Stephen Earl, Jr.

241

Magnetic and structural properties of NaLnMnWO6 and NaLnMgWO6 perovskites  

NASA Astrophysics Data System (ADS)

We have prepared 14 new AA?BB?O6 perovskites which possess a rock salt ordering of the B-site cations and a layered ordering of the A-site cations. The compositions obtained are NaLnMnWO6 (Ln=Ce, Pr, Sm, Gd, Dy, and Ho) and NaLnMgWO6 (Ln=Ce, Pr, Sm, Eu, Gd, Tb, Dy, and Ho). The samples were structurally characterized by powder X-ray diffraction which has revealed metrically tetragonal lattice parameters for compositions with Ln=Ce, Pr and monoclinic symmetry for compositions with smaller lanthanides. Magnetic susceptibility vs. temperature measurements have found that all six NaLnMnWO6 compounds undergo antiferromagnetic ordering at temperatures between 10 and 13 K. Several compounds show signs of a second magnetic phase transition. One sample, NaPrMnWO6, appears to pass through at least three magnetic phase transitions within a narrow temperature range. All eight NaLnMgWO6 compounds remain paramagnetic down to 2 K revealing that the ordering of the Ln3+ cations in the NaLnMnWO6 compounds is induced by the ordering of the Mn2+ sub-lattice.

King, Graham; Wayman, Lora M.; Woodward, Patrick M.

2009-06-01

242

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.

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

2012-01-01

243

Na/K/Cl cotransport in cultured human fibroblasts.  

PubMed

The transport characteristics and regulation of the Na/K/Cl cotransport system were investigated in cultured human fibroblasts (HSWP cells). The existence of the system was documented by the finding that digitoxin-insensitive K+ influx was dependent upon the presence of both Na+ and Cl- in the extracellular milieu. It was found that only Br- could partially substitute for Cl-, with SCN-, I-, acetate, and gluconate being ineffective. Li+ could partially substitute for Na+; however, choline was without effect. The shape of the titration curves for K+ influx versus extracellular Cl- concentration was dependent upon the substituted anion. Furthermore, the apparent Km for Cl- at saturating [K+]o and [Na+]o, was also dependent upon the substituted anion and ranged from 30 mM (gluconate substitution) to 100 mM (acetate substitution). The titration curves for K+ influx versus extracellular Na+ concentration displayed hyperbolic kinetics and the apparent Km = 15 mM at saturating [K+]o. The curve for K+ influx versus extracellular K+ concentration was a hyperbola and the apparent Km for K+ = 3 mM at saturating [Na+]o. The digitoxin-insensitive K+ flux was found to be sensitive to related 5-sulfamoylbenzoic acid derivatives, commonly known as "loop" diuretics and to be insensitive to both: amiloride (3,5-diamino-N-(aminoiminomethyl)-6-chloropyrazinecarboxamide++ +) and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid. The Na/K/Cl cotransport system was not stimulated by serum, but was slightly stimulated by two peptide mitogens. Furthermore, agents which cause an elevation in cellular cyclic AMP levels were found to be potent inhibitors of cotransport. PMID:2981857

Owen, N E; Prastein, M L

1985-02-10

244

New CsI:Na-selenium x-ray detector  

NASA Astrophysics Data System (ADS)

Digital x-ray imager known to flat-panel detector has been studied for the application of a various medical modalities. Currently, two types of detection methods have been realized in digital radiography. One is an indirect conversion method and the other is a direct conversion method. we have been developing a new x-ray detector that combines a columnar CsI:Na scintillation layer with a photosensitive a-Se with dielectric thin film. In this structure, an x-ray is converted to visible light in a CsI:Na scintillation layer and visible light is then converted to electric charges in a-Se layer. The electron-hole pairs can be also generated from x-ray interaction in the a-Se photoconductor, which can improve the detection efficiency of electric charge. We designed the thickness of CsI:Na scintillator by using computer simulation. MCNP is a general-purpose, continuous-energy, generalized-geometry, time-dependent, coupled neutron / photon / electron Monte Carlo transport code. The spectra of x-ray absorption was simulated by using MCNP 4C code. The morphology of the vacuum deposited CsI:Na scintillator and the parylene film were analyzed. Photoluminescence characterization of CsI:Na showed a light emission peak centered at 420nm as expected, which matched the absorption spectrum of amorphous selenium(a-Se). For an electric field of 10V/?m, the dark currents of our detector were below 370 pA/cm2 and the SNR of CsI:Na coupled a-Se detector with a dielectric layer was 1.8 times greater than that without CsI:Na layer.

Seok, Dae Woo; Choi, Jang Yong; Kang, Sang Sik; Jang, Gi Won; Mun, Chi Woong; Nam, Sang Hee

2004-05-01

245

Hypoxia induced by Na 2S 2O 4 increases [Na +] i in mouse glomus cells, an effect depressed by cobalt. Experiments with Na +-selective microelectrodes and voltage-clamping  

Microsoft Academic Search

The intracellular sodium concentration ([Na+]i) and resting potential (Em) of cultured mouse glomus cells (clustered and isolated) were simultaneously measured with intracellular Na+-sensitive and conventional, KCl-filled, microelectrodes. Results obtained in clustered and isolated cells were similar. During normoxia (PO2 122 Torr), [Na+]i was 12–13 mM corresponding to a Na+ equilibrium potential (ENa) of about 58 mV. Em was about ?42

R.-G Jiang; X.-Q Zhang; C Eyzaguirre

1998-01-01

246

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

Microsoft Academic Search

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

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

2011-01-01

247

The Effects of Na Movement on Surgical Myocardial Protection: The Role of the Na+-H+ Exchange System and Na-Channel in the Development of Ischemia and Reperfusion Injury  

Microsoft Academic Search

Objectives: We investigated whether the Na +-H+ exchange inhibitor, HOE642 (Hoe), and\\/or the Na channel blocker, mexiletine (Mex), enhance a cardioprotective effect on St. Thomas' Hospi- tal cardioplegic solution (STS) to clarify the mechanism by which intracellular Na + is accumu- lated after cardioplegic arrest. Materials and Methods: Isolated working rat hearts were perfused with Krebs-Henseleit bicar- bonate buffer (KHBB).

Ke-Xiang Liu; Fumio Yamamoto; Hiroshi Yamamoto; Tiance Wang; Zhicheng Zhu; Rihao Xu; Shudong Zhang

248

Actions of ATX-II and other gating-modifiers on Na(+) currents in HEK-293 cells expressing WT and DeltaKPQ hNa(V) 1.5 Na(+) channels.  

PubMed

Voltage-gated Na(+) channels underlie the action potential upstroke in excitable cells, and both natural and synthetic inactivation inhibitors prolong the Na(+) current (I(Na)). The effects of Na(+) channel mutations on these pharmacological actions are incompletely investigated. Therefore, I compared the effects of inactivation inhibitors on I(Na) in WT or mutant (DeltaKPQ) human cardiac Na(+) channels expressed in HEK-293 cells, by measuring difference currents sensitive to 50muM tetrodotoxin. Veratridine and the pyrethroid tefluthrin prolonged I(Na) in WT and DeltaKPQ without obvious differential effects, while a sea anemone toxin (ATX-II) and a synthetic inotrope (SDZ 201-106) prolonged WT I(Na), but apparently blocked I(Na) in the DeltaKPQ mutant. This block was due, at least in-part, to enhanced steady-state inactivation, with half-inactivation potentials shifted by up to -17mV. Inactivation enhancement by ATX-II also persisted when conditioning depolarizations were abbreviated, and was unaffected by the additional presence of SDZ 201-106 consistent with these agents having unique interactions with DeltaKPQ Na(+) channels. It is concluded that the toxin-binding sites for ATX-II and SDZ 201-106 have allosteric effects converging on a common path affecting steady-state inactivation of DeltaKPQ I(Na). Pharmacological modulation of this path to increase inactivation in mutant Na(+) channels could potentially produce therapeutic benefits. PMID:18996139

Spencer, C Ian

2008-11-01

249

EDITORIAL: TaCoNa-Photonics 2008 TaCoNa-Photonics 2008  

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

250

High Pressure Study of K-Na Hollandite Solid Solution  

NASA Astrophysics Data System (ADS)

(Na, K)AlSi3O8 aluminosilicates hollandite-type materials with their dense structure, in which all Si and Al are in six-fold coordination, are considered as a possible repository of potassium and sodium in the Earth's lower mantle. Phase relations in the system KAlSi3O8 - NaAlSi3O8 have been examined by other workers at pressures of 5 - 23 GPa and temperatures of 700 - 1200°C, indicating that the maximum solubility of NaAlSi3O8 component into KAlSi3O8 hollandite-type structure at 1000°C is about 40 mol%. At higher Na content the high pressure phase appears to be that of the calcium-ferrite type structure. However, in the last few years there have been a number of reports of natural occurrences of NaAlSi3O8 hollandite in shock-induced melt veins of chondrite. Aim of our research is, therefore, to extent the study of the phase relation of the K-Na system at higher temperature and to determine the physical-chemical properties and high-pressure behaviour of silicate hollandite-type structures containing K and Na in different concentrations. A series of synthesis experiments has been done with the multi-anvil presses at the Bayerisches Geoinstitut in the pressure range 13-25 GPa and 1700°C, using KxNa1-xAlSi3O8 (x = 1, 0.7, 0.5, 0.4) glasses as the starting materials. X-ray powder diffraction analysis and electron microprobe measurements of the run products show that at 20GPa, pure K0.7Na0.3AlSi3O8 hollandite has been synthesized, with the lattice parameters of a = 9.3133 (5) Å, c = 2.7226 (2) Å, V = 236.15 (2) Å3. At 22 GPa, pure K0.5Na0.5AlSi3O8 hollandite has been synthesized, with the lattice parameters of a = 9.2984 (4) Å, c = 2.71920 (17) Å, V = 235.103 (15) Å3. The pressure stability field of KxNa1-xAlSi3O8 hollandite appears therefore larger than in the study of privious work. High-pressure X-ray powder and single-crystal diffraction and Raman spectroscopy experiments for this composition are in progress. Preliminary experiments using a NaAlSi3O8 end-member glass yield no hollandite-type structure at 22.5GPa and 1700°C. Further synthesis experiments are planned to determine the experimental P-T stability field of NaAlSi3O8 hollandite.

Liu, J.; Boffa-Ballaran, T.; Dubrovinsky, L.; Frost, D.

2005-12-01

251

Oxidant-induced formation of a neutral flavosemiquinone in the Na+-translocating NADH:Quinone oxidoreductase (Na+-NQR) from Vibrio cholerae.  

PubMed

The Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) from the human pathogen Vibrio cholerae is a respiratory flavo-FeS complex composed of the six subunits NqrA-F. The Na(+)-NQR was produced as His(6)-tagged protein by homologous expression in V. cholerae. The isolated complex contained near-stoichiometric amounts of non-covalently bound FAD (0.78 mol/mol Na(+)-NQR) and riboflavin (0.70 mol/mol Na(+)-NQR), catalyzed NADH-driven Na(+) transport (40 nmol Na(+)min(-1) mg(-1)), and was inhibited by 2-n-heptyl-4-hydroxyquinoline-N-oxide. EPR spectroscopy showed that Na(+)-NQR as isolated contained very low amounts of a neutral flavosemiquinone (10(-3) mol/mol Na(+)-NQR). Reduction with NADH resulted in the formation of an anionic flavosemiquinone (0.10 mol/mol Na(+)-NQR). Subsequent oxidation of the Na(+)-NQR with ubiquinone-1 or O(2) led to the formation of a neutral flavosemiquinone (0.24 mol/mol Na(+)-NQR). We propose that the Na(+)-NQR is fully oxidized in its resting state, and discuss putative schemes of NADH-triggered redox transitions. PMID:18454933

Tao, Minli; Casutt, Marco S; Fritz, Günter; Steuber, Julia

2008-04-11

252

NMR Evidence for Complexing of Na+ in Muscle, Kidney, and Brain, and by Actomyosin. The Relation of Cellular Complexing of Na+ to Water Structure and to Transport Kinetics  

PubMed Central

The nuclear magnetic resonance (NMR) spectrum of Na+ is suitable for qualitative and quantitative analysis of Na+ in tissues. The width of the NMR spectrum is dependent upon the environment surrounding the individual Na+ ion. NMR spectra of fresh muscle compared with spectra of the same samples after ashing show that approximately 70% of total muscle Na+ gives no detectable NMR spectrum. This is probably due to complexation of Na+ with macromolecules, which causes the NMR spectrum to be broadened beyond detection. A similar effect has been observed when Na+ interacts with ion exchange resin. NMR also indicates that about 60% of Na+ of kidney and brain is complexed. Destruction of cell structure of muscle by homogenization little alters the per cent complexing of Na+. NMR studies show that Na+ is complexed by actomyosin, which may be the molecular site of complexation of some Na+ in muscle. The same studies indicate that the solubility of Na+ in the interstitial water of actomyosin gel is markedly reduced compared with its solubility in liquid water, which suggests that the water in the gel is organized into an icelike state by the nearby actomyosin molecules. If a major fraction of intracellular Na+ exists in a complexed state, then major revisions in most theoretical treatments of equilibria, diffusion, and transport of cellular Na+ become appropriate.

Cope, Freeman W.

1967-01-01

253

The renal electrogenic Na+:HCO-3 cotransporter.  

PubMed

The electrogenic Na+:HCO3- cotransporter (symporter) is the major transporter for HCO3- reabsorption across the basolateral membrane of the renal proximal tubule and also contributes significantly to Na+ reabsorption. We expression-cloned the salamander renal electrogenic Na+:Bicarbonate Cotransporter (NBC) in Xenopus laevis oocytes. After injecting poly(A)+ RNA, fractionated poly(A)+ RNA or cRNA, we used microelectrodes to monitor membrane potential (Vm) and intracellular pH (pHi) All solutions contained ouabain to block the Na+/K+ pump (P-ATPase). After applying 1.5% CO2/10 mmol l-1 HCO3- (pH 7.5) and allowing pHi to stabilize from the CO2-induced acidification, we removed Na+. In native oocytes or water-injected controls, removing Na+ hyperpolarized the cell by -5 mV and had no effect on pHi. In oocytes injected with poly(A)+ RNA, removing Na+ transiently depolarized the cell by -10 mV and caused pHi to decrease; both effects were blocked by 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS) and required HCO3-. We enriched the signal by electrophoretic fractionation of the poly(A)+ RNA, and constructed a size-selected cDNA library in pSPORT1 using the optimal fraction. Screening the Ambystoma library yielded a single clone (aNBC). Expression was first obvious 3 days after injection of NBC cRNA. Adding CO2/HCO3- induced a large (> 50 mV) and rapid hyperpolarization, followed by a partial relaxation as pHi stabilized. Subsequent Na+ removal depolarized the cell by more than 40 mV and decreased pHi. aNBC is a full-length clone with a start Met and a poly(A)+ tail; it encodes a protein with 1025 amino acids and several putative membrane-spanning domains. aNBC is the first member of a new family of Na(+)-linked HCO3- transporters. We used aNBC to screen a rat kidney cDNA library, and identified a full-length cDNA clone (rNBC) that encodes a protein of 1035 amino acids. rNBC is 86% identical to aNBC and can be functionally expressed in oocytes. PMID:9050234

Boron, V F; Hediger, M A; Boulpaep, E L; Romero, M F

1997-01-01

254

Kinetic comparisons of heart and kidney Na+,K(+)-ATPases.  

PubMed

Most kinetic measurements of the partial reactions of Na(+),K(+)-ATPase have been conducted on enzyme from mammalian kidney. Here we present a kinetic model that is based on the available equilibrium and kinetic parameters of purified kidney enzyme, and allows predictions of its steady-state turnover and pump current in intact cells as a function of ion and ATP concentrations and the membrane voltage. Using this model, we calculated the expected dependence of the pump current on voltage and extracellular Na(+) concentration. The simulations indicate a lower voltage dependence at negative potentials of the kidney enzyme in comparison with heart muscle Na(+),K(+)-ATPase, in agreement with experimental results. The voltage dependence is enhanced at high extracellular Na(+) concentrations. This effect can be explained by a voltage-dependent depopulation of extracellular K(+) ion binding sites on the E2P state and an increase in the proportion of enzyme in the E1P(Na(+))(3) state in the steady state. This causes a decrease in the effective rate constant for occlusion of K(+) by the E2P state and hence a drop in turnover. Around a membrane potential of zero, negligible voltage dependence is observed because the voltage-independent E2(K(+))(2) ? E1 + 2K(+) transition is the major rate-determining step. PMID:22947929

Garcia, Alvaro; Rasmussen, Helge H; Apell, Hans-Jürgen; Clarke, Ronald J

2012-08-22

255

Kinetic Comparisons of Heart and Kidney Na+,K+-ATPases  

PubMed Central

Most kinetic measurements of the partial reactions of Na+,K+-ATPase have been conducted on enzyme from mammalian kidney. Here we present a kinetic model that is based on the available equilibrium and kinetic parameters of purified kidney enzyme, and allows predictions of its steady-state turnover and pump current in intact cells as a function of ion and ATP concentrations and the membrane voltage. Using this model, we calculated the expected dependence of the pump current on voltage and extracellular Na+ concentration. The simulations indicate a lower voltage dependence at negative potentials of the kidney enzyme in comparison with heart muscle Na+,K+-ATPase, in agreement with experimental results. The voltage dependence is enhanced at high extracellular Na+ concentrations. This effect can be explained by a voltage-dependent depopulation of extracellular K+ ion binding sites on the E2P state and an increase in the proportion of enzyme in the E1P(Na+)3 state in the steady state. This causes a decrease in the effective rate constant for occlusion of K+ by the E2P state and hence a drop in turnover. Around a membrane potential of zero, negligible voltage dependence is observed because the voltage-independent E2(K+)2 ? E1 + 2K+ transition is the major rate-determining step.

Garcia, Alvaro; Rasmussen, Helge H.; Apell, Hans-Jurgen; Clarke, Ronald J.

2012-01-01

256

Correlation-bound anions of NaCl clusters.  

PubMed

In the past a variety of electron binding motifs has been identified for sodium chloride cluster anions. As for all of these clusters the excess electron is predicted to be bound in self-consistent-field calculations, the different binding mechanisms can be understood in terms of a one-electron potential largely due to the permanent multipole moments of the neutral cluster. Here we investigate a new class of (NaCl)(N)(-) anion that is predicted to be bound only after electron correlation has been taken into account. Correlation-bound states of the trimer, (NaCl)(3)(-), and tetramer, (NaCl)(4)(-), are characterized using Green's function and an equation-of-motion coupled-cluster method, and the computed electron binding energies as well as the distributions of the excess electrons as inferred from natural orbitals of the coupled-cluster calculations are compared with that of dipole-bound, quadrupole-bound, and defectlike (NaCl)(N)(-) anions. For the (NaCl)(4)(-) tetramer anion the correlation-bound state is predicted to represent the most stable isomer. Our results provide a sensitive test case for the development of improved one-electron model potentials for excess electrons bound to alkali halide clusters, and suggest that cluster abundance as inferred from peak intensities of photoelectron spectra is not directly related to the relative stability of the clusters. PMID:20866133

Sommerfeld, Thomas; Bhattarai, Bijay; Vysotskiy, Victor P; Cederbaum, Lorenz S

2010-09-21

257

Correlation-bound anions of NaCl clusters  

NASA Astrophysics Data System (ADS)

In the past a variety of electron binding motifs has been identified for sodium chloride cluster anions. As for all of these clusters the excess electron is predicted to be bound in self-consistent-field calculations, the different binding mechanisms can be understood in terms of a one-electron potential largely due to the permanent multipole moments of the neutral cluster. Here we investigate a new class of (NaCl)N- anion that is predicted to be bound only after electron correlation has been taken into account. Correlation-bound states of the trimer, (NaCl)3-, and tetramer, (NaCl)4-, are characterized using Green's function and an equation-of-motion coupled-cluster method, and the computed electron binding energies as well as the distributions of the excess electrons as inferred from natural orbitals of the coupled-cluster calculations are compared with that of dipole-bound, quadrupole-bound, and defectlike (NaCl)N- anions. For the (NaCl)4- tetramer anion the correlation-bound state is predicted to represent the most stable isomer. Our results provide a sensitive test case for the development of improved one-electron model potentials for excess electrons bound to alkali halide clusters, and suggest that cluster abundance as inferred from peak intensities of photoelectron spectra is not directly related to the relative stability of the clusters.

Sommerfeld, Thomas; Bhattarai, Bijay; Vysotskiy, Victor P.; Cederbaum, Lorenz S.

2010-09-01

258

NaIrO3—A pentavalent post-perovskite  

NASA Astrophysics Data System (ADS)

Sodium iridium (V) oxide, NaIrO3, was synthesized by a high pressure solid state method and recovered to ambient conditions. It is found to be isostructural with CaIrO3, the much-studied structural analog of the high-pressure post-perovskite phase of MgSiO3. Among the oxide post-perovskites, NaIrO3 is the first example with a pentavalent cation. The structure consists of layers of corner- and edge-sharing IrO6 octahedra separated by layers of NaO8 bicapped trigonal prisms. NaIrO3 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.Graphical abstractSodium iridium(V) oxide, NaIrO3, synthesized by a high pressure solid state method and recovered to ambient conditions is found to crystallize as the post-perovskite structure and is the first example of a pentavalent ABO3 post-perovskite.

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

2011-03-01

259

Na[superscript +] binding to meizothrombin desF1  

SciTech Connect

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

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

2009-06-10

260

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.

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

2012-01-01

261

Thermodynamics of NaOH(aq) in hydrothermal solutions  

SciTech Connect

Apparent molar volumes and osmotic coefficients of NaOH solutions, calculated from critically evaluated literature data on volumes and vapor pressures, were used to fit the Pitzer equations to yield ion-interaction parameters as a function of temperature and pressure. These parameters allow the calculation of osmotic activity coefficients from 0-350/sup 0/C, saturation pressure to about 400 bars and 0-10 molal NaOH, and volumetric properties at saturation pressure over the same temperature and concentration range. Because the parameters for osmotic and activity coefficients above 300/sup 0/C are based on less precise data, and because of possible ion-pairing above this temperature, calculated values above 300/sup 0/C are considered only as best estimates available at this time. Partial molar volumes at infinite dilution calculated for NaOH are combined with literature data for NaCl, HCl, and H/sub 2/O to yield the pressure dependence of the ionization of water to 200/sup 0/C, and are also combined with the potentiometric data of SWEETON et al. (1974) on the ionization of water to calculate the infinitely dilute partial molar volume of HCl to 300/sup 0/C. Specific volumes of NaOH solutions at saturation pressure and up to 350/sup 0/C are also calculated and tabulated.

Pabalan, R.T.; Pitzer, K.S.

1987-04-01

262

Thermodynamics of NaOH(aq) in hydrothermal solutions  

NASA Astrophysics Data System (ADS)

Apparent molar volumes and osmotic coefficients of NaOH solutions, calculated from critically evaluated literature data on volumes and vapor pressures, were used to fit the Pitzer equations to yield ion-interaction parameters as a function of temperature and pressure. These parameters allow the calculation of osmotic and activity coefficients from 0-350°C, saturation pressure to about 400 bars and 0-10 molal NaOH, and volumetric properties at saturation pressure over the same temperature and concentration range. Because the parameters for osmotic and activity coefficients above 300°C are based on less precise data, and because of possible ion-pairing above this temperature, calculated values above 300°C are considered only as best estimates available at this time. Partial molar volumes at infinite dilution calculated for NaOH are combined with literature data for NaCl, HCl, and H 2 O to yield the pressure dependence of the ionization of water to 200°C, and are also combined with the potentiometric data of Sweeton et al . (1974) on the ionization of water to calculate the infinitely dilute partial molar volume of HCl to 300°C. Specific volumes of NaOH solutions at saturation pressure and up to 350°C are also calculated and tabulated.

Pabalan, Roberto T.; Pitzer, Kenneth S.

1987-04-01

263

ANALISIS SIFAT FOTOSENSITIVITAS SENYAWA ANTIBAKTERI TURUNAN FLUOROKUINOLON BERDASARKAN DATA TRANSISI ELEKTRONIK DAN SELISIH ENERGI ORBITAL HOMO-LUMO PHOTOSENSITIVITY ANALYSIS OF FLUOROQUINOLONE ANTIBACTERIAL COMPOUNDS BASED ON ELECTRONIC TRANSITIONS DATA AND HOMO-LUMO ENERGY BAND GAP  

Microsoft Academic Search

INTISARI Telah dilakukan analisis sifat fotosensitivitas dari senyawa antibakteri fluorokuinolon berdasarkan karakteristik spektra elektronik dan selisih energi HOMO-LUMO. Perhitungan spektra elektronik dilakukan menggunakan metode semiempirik ZINDO\\/s untuk mengetahui sifat fotosensitivitasnya pada daerah ultraviolet (?=200-400 nm) untuk molekul pada fasa gas dalam bentuk ion zwitter-nya. Perhitungan selisih energi HOMO-LUMO dilakukan untuk memprediksikan kekuatan fotosensitivitas dari senyawa antibakteri tersebut. Kedua proses perhitungan

Iqmal Tahir; Faiz El Makky; Harno Dwi Pranowo; Karna Wijaya

264

The activity coefficients of Fe(III) hydroxide complexes in NaCl and NaClO4 solutions  

NASA Astrophysics Data System (ADS)

The osmotic coefficients of FeCl3 at 25 °C from 0.15 to 1.7 m [Rumyantsev et al., Z. Phys. Chem., 218, 1089 1127, 2004] have been used to determine the Pitzer parameters (?(0), ?(1) and C?) for FeCl3. Since the differences in the Pitzer coefficients of rare earths in NaCl and NaClO4 are small, the values of Fe(ClO4)3 have been estimated using the differences between La(ClO4)3 and LaCl3. The Pitzer coefficients for FeCl3 combined with enthalpy and heat capacity data for the rare earths can be used to estimate the activity coefficients of Fe3+ in NaCl over a wide range of temperatures (0 to 50 °C) and ionic strength (0 to 6 m). The activity coefficients of Fe3+ in NaCl and NaClO4 solutions have been used to determine the activity coefficients of Fe(OH)2+ in these solutions from the measured first hydrolysis constants of Fe3+ [Byrne et al., Mar. Chem., 97, 34 48, 2005]. The activity coefficients of Fe(OH)2+, Fe(OH)3 and Fe(OH)4- from 0 to 50 °C have also been determined from the solubility measurements of Fe(III) in NaCl solutions [Liu and Millero, Geochim. Cosmochim Acta, 63, 3487 3497, 1999]. These activity coefficients have been fitted to the Pitzer equations. These results can be used to estimate the speciation of Fe(III) with OH- in natural waters with high concentrations of NaCl from 0 to 50 °C.

Millero, Frank J.; Pierrot, Denis

2007-10-01

265

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

Microsoft Academic Search

Ion-selective microelectrodes are a powerful tool in studying adaptive responses of plant cells and tissues to various abiotic stresses. However, application of this technique in Na+ flux measurements was limited due to poor selectivity for Na+ ions of commercially available Na+ cocktails. Often, these cocktails cannot discriminate between Na+ and other interfering ions such as K+ and Ca2+, leading to

Maheswari Jayakannan; Olga Babourina; Zed Rengel

2011-01-01

266

NaOH Recovery from MEROX Tower Waste Stream Using the Electrodialysis Process  

Microsoft Academic Search

Electrodialysis with two different configurations was used for the recovery of NaOH from the waste stream of a MEROX tower. For this purpose, the effects of cell applied voltage and initial Na concentration in the feed solution on NaOH recovery and current efficiency were studied. Results showed that the recovery and current efficiency were improved by increasing the initial Na

Narjes Keramati; Ahmad Moheb; Mohammad Reza Ehsani

2010-01-01

267

Mechanism of control of Na,K-ATPase in principal cells of the mammalian collecting duct.  

PubMed

The collecting duct is the site of final Na reabsorption according to Na balance requirements. Using isolated rat cortical collecting ducts (CCD) and mpkCCD(cl4) cells, a mouse cortical collecting duct cell line, we have studied the physiological control of Na,K-ATPase, the key enzyme that energizes Na reabsorption. Aldosterone, a major regulator of Na transport by the collecting duct, stimulates Na,K-ATPase activity through both recruitment of intracellular pumps and increased total amounts of Na pump subunits. This effect is observed after a lag time of 1 hour and is independent of Na entry through ENaC, but requires de novo transcription and translation. Vasopressin and cAMP, its second messenger, stimulate Na,K-ATPase activity within minutes through translocation of Na pumps from a brefeldin A-sensitive intracellular pool to the plasma membrane. Dysregulation of collecting duct Na,K-ATPase activity is at least in part responsible of the Na retention observed in nephritic syndrome. In this setting, Na,K-ATPase activity and subunit synthesis are specifically increased in CCD. In conclusion, aldosterone, vasopressin, and intracellular Na control the cell surface expression of Na,K-ATPase and translocation from intracellular stores is a major mechanism of regulation of Na,K-ATPase activity in collecting duct principal cells. PMID:12763891

Féraille, Eric; Mordasini, David; Gonin, Sandrine; Deschênes, Georges; Vinciguerra, Manlio; Doucet, Alain; Vandewalle, Alain; Summa, Vanessa; Verrey, François; Martin, Pierre-Yves

2003-04-01

268

Time course of adaptation to low and high NaCl diets in the domestic fowl  

Microsoft Academic Search

White Plymouth Rock fowls (2.5–5.5 kg, mostly laying hens) were maintained onlow NaCl treatment (L: balanced ration and distilled water; mean Na+ intakes 0.2–0.3 m-mole\\/kg bw.d depending on experiment) orhigh NaCl treatment (H: balanced ration with 1% w\\/w NaCl+0.5% w\\/v NaCl drink; mean Na+ intakes 10–13.5 m-mole\\/kg d). DuringNaCl depletion (birds adapted to H, then switched to L for 1,

E. Skadhauge; D. H. Thomas; A. Chadwick; M. Jallageas

1983-01-01

269

Binding energy and structure of e+Na  

NASA Astrophysics Data System (ADS)

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

Shertzer, J.; Ward, S. J.

2010-06-01

270

Fast light of CsI(Na) crystals  

NASA Astrophysics Data System (ADS)

The responses of different common alkali halide crystals to alpha-rays and gamma-rays are tested in this research. It is found that only CsI(Na) crystals have significantly different waveforms between alpha and gamma scintillations, while others do not exhibit this phenomena. The rise time of the fast light is about 5 ns and the decay time is 17±12 ns. It is suggested that the fast light of CsI(Na) crystals arises from the recombination of free electrons with self-trapped holes of the host crystal CsI. Self-absorption limits the emission of fast light of CsI(Tl) and NaI(Tl) crystals.

Sun, Xi-Lei; Lü, Jun-Guang; Hu, Tao; Zhou, Li; Cao, Jun; Wang, Yi-Fang; Zhan, Liang; Yu, Bo-Xiang; Cai, Xiao; Fang, Jian; Xie, Yu-Guang; An, Zheng-Hua; Wang, Zhi-Gang; Xue, Zhen; Zhang, Ai-Wu; Lü, Qi-Wen; Ning, Fei-Peng; Ge, Yong-Shuai; Liu, Ying-Biao

2011-12-01

271

Theoretical simulation of the photoassociation process for NaCs  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

272

HARP and NA61 (SHINE) hadron production experiments  

SciTech Connect

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

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

2009-11-25

273

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

PubMed

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

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

2012-04-11

274

A study of the reaction between NaHCO3 and H: Apparent closure on the chemistry of mesospheric Na  

NASA Astrophysics Data System (ADS)

The reaction between sodium bicarbonate (NaHCO3) and atomic H is the only likely route (apart possibly from daytime photolysis) for recycling this major sodium reservoir back to atomic Na in the upper mesosphere. The rate coefficient was determined for the first time by reacting NaHCO3 in a known excess of H in a fast flow tube, yielding k(227 K) = (1.7 ± 0.6) × 10-13 and k(307 K) = (5.2 ± 2.5) × 10-13 cm3 molecule-1 s-1. These measurements are very well described by transition state theory, using ab initio quantum calculations of the saddle points on the reaction potential energy surface. The resulting temperature dependence of the rate coefficient is then given by k(100-400 K) = 1.84 × 10-13 T0.78exp -(1014+130-96/T) cm3 molecule-1 s-1. When k(T) is extrapolated to 180-220 K, there is excellent agreement with the value predicted from atmospheric models of the nighttime Na layer. Hence this measurement has, to a first order, demonstrated closure of the neutral chemistry governing the underside of the Na layer above 80 km.

Cox, Rachel M.; Self, Daniel E.; Plane, John M. C.

2001-01-01

275

Translated anti-sense product of the Na/phosphate co-transporter (NaPi-II).  

PubMed Central

The homeostasis of Pi in marine teleosts is maintained by renal Pi secretion as well as by Pi reabsorption. A Na/Pi co-transport system belonging to the NaPi-II protein family is instrumental in tightly controlled renal Pi handling in mammals and fish. We have isolated an NaPi-II related cDNA from winter flounder. It was cloned from a female gonad cDNA library and is 624 bp long. The transcript is expressed in female and male flounder gonads as well as in kidney and intestine, although at very low levels. RNase H digestion experiments revealed an opposite orientation of the transcript with regard to NaPi-II-related mRNA. The anti-sense orientation was confirmed by genomic sequence analysis and Southern blotting. Alluding to the sense transcript, the anti-sense transcript was denoted IPAN. The open reading frame of IPAN encodes a basic protein of 68 amino acid residues. Immunohistochemistry confined the anti-sense related protein, Ipan, to a submembranous compartment of immature oocytes, suggesting a role in oocyte development. In kidney and intestine Ipan is partly co-localized with the Na/Pi co-transporter, implying a regulatory function for the anti-sense protein. However, direct protein-protein interaction could not be established. The existence of a putative open reading frame in other species extends the biological significance of the novel protein.

Huelseweh, B; Kohl, B; Hentschel, H; Kinne, R K; Werner, A

1998-01-01

276

Differential sensitivity of stomatal and non-stomatal components to NaCl or Na2SO4 salinity in horsegram, Macrotyloma uniflorum (Lam.)  

Microsoft Academic Search

14CO2 assimilation rate (P), leaf diffusive conductance (gs), photosynthetic electron flow, and activities of enzymes of Calvin cycle were studied in a horsegram [Macrotyloma uniflorum (Lam.)] in response to salinity induced by NaCl or Na2SO4. A significant reduction in P and gs by both salt treatments was registered. Na2SO4 caused a greater reduction in gs than the NaCl salinity. Studies

P. Sreenivasulu Reddy; S. Ramanjulu; C. Sudhakar; K. Veeranjaneyulu

1998-01-01

277

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

Microsoft Academic Search

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

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

1999-01-01

278

Stimulation of Na+ transport by AVP is independent of PKA phosphorylation of the Na-K-ATPase in collecting duct principal cells.  

PubMed

Arginine-vasopressin (AVP) stimulates Na(+) transport and Na-K-ATPase activity via cAMP-dependent PKA activation in the renal cortical collecting duct (CCD). We investigated the role of the Na-K-ATPase in the AVP-induced stimulation of transepithelial Na(+) transport using the mpkCCD(c14) cell model of mammalian collecting duct principal cells. AVP (10(-9) M) stimulated both the amiloride-sensitive transepithelial Na(+) transport measured in intact cells and the maximal Na pump current measured by the ouabain-sensitive short-circuit current in apically permeabilized cells. These effects were associated with increased Na-K-ATPase cell surface expression, measured by Western blotting after streptavidin precipitation of biotinylated cell surface proteins. The effects of AVP on Na pump current and Na-K-ATPase cell surface expression were dependent on PKA activity but independent of increased apical Na(+) entry. Time course experiments revealed that in response to AVP, the cell surface expression of both endogenous Na-K-ATPase and hybrid Na pumps containing a c-myc-tagged wild-type human alpha(1)-subunit increased transiently. Na-K-ATPase cell surface expression was maximal after 30 min and then declined toward baseline after 60 min. Immunoprecipitation experiments showed that PKA activation did not alter total phosphorylation levels of the endogenous Na-K-ATPase alpha-subunit. In addition, mutation of the PKA phosphorylation site (S943A or S943D) did not alter the time course of increased cell surface expression of c-myc-tagged Na-K-ATPase in response to AVP or to dibutyryl-cAMP. Therefore, stimulation of Na-K-ATPase cell surface expression by AVP is dependent on PKA but does not rely on alpha(1)-subunit phosphorylation on serine 943 in the collecting duct principal cells. PMID:15972390

Mordasini, David; Bustamante, Mauro; Rousselot, Martine; Martin, Pierre-Yves; Hasler, Udo; Féraille, Eric

2005-06-21

279

Male\\/female differences in intracellular Na +regulation during ischemia\\/reperfusion in mouse heart  

Microsoft Academic Search

We previously showed that ?-adrenergic stimulation revealed male\\/female differences in susceptibility to ischemia\\/reperfusion (I\\/R) injury. To explore whether altered [Na+]i regulation is involved in the mechanism of this sex difference, we measured [Na+]i by 23Na NMR spectroscopy in isolated perfused mouse hearts. [Na+]i increased to 195 ± 3% (mean ± S.E.) of the pre-ischemic level at 20 min of ischemia in male hearts, whereas [Na+]i

Kenichi Imahashi; Robert E. London; Charles Steenbergen; Elizabeth Murphy

2004-01-01

280

Kinetic Mechanism of Na + Glucose Cotransport through the Rabbit Intestinal SGLT1 Protein  

Microsoft Academic Search

No consensus has yet been reached regarding the order of substrate addition to the high-affinity Na +-D-glucose cotransporter (SGLT1). This problem was addressed by computer-assisted derivation of the steady-state velocity equations characterizing the eight-state Na +:Na +:substrate (NNS) and Na +:substrate:Na +(NSN) mechanisms of cotransport. A notable difference was found in their denominator expressions and used to device a new

A. Berteloot

2003-01-01

281

Characterization of Na+ transport across the cell membranes of the ascending thin limb of Henle's loop  

Microsoft Academic Search

Characterization of Na+ transport across the cell membranes of the ascending thin limb of Henle's loop. In the ascending thin limb of Henle's loop (ATL), intracellular Na+ is extruded by Na+\\/K+ ATPase in the basolateral membrane. To further characterize Na+ transport across the cell membranes of the ATL, the intracellular sodium concentration ([Na+]i) was monitored using a sodium-sensitive fluorescent probe,

Nobuyuki Takahashi; Yoshiaki Kondo; Ikuma Fujiwara; Osamu Ito; Yutaka Igarashi; Keishi Abe

1995-01-01

282

Is potassium co-transported by the cardiac NaCa exchange?  

Microsoft Academic Search

It has been suggested that the stoichiometry of the electrogenic Na-Ca exchange is 3Na:1Ca. Recently, however, it was reported in rod outer segments that the stoichiometry of Na-Ca exchange is not 3Na:1Ca but 4Na:1Ca+1K. In cardiac cells, the reversal potential has always been measured in the absence of K or at a very low K concentration. We have, therefore, re-examined

K. Yasui; J. Kimura

1990-01-01

283

Hot corrosion of cordierite ceramics by Na and K-salts  

Microsoft Academic Search

The corrosion behavior of cordierite ceramics by Na-salts (NaCl and Na2SO4) and K-salts (KCl and K2SO4) was studied at high temperatures between 700 and 1200 °C. In case of the corrosion by Na-salts at 1000 °C, small idiomorphic crystals were formed on the surface of the sample. They were identified with MgO and Mg2SiO4 in the corrosion by NaCl and

Junichi Takahashi; Yoshie Kawai; Shiro Shimada

1998-01-01

284

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

285

Thermodynamics Properties of Oxymatrine in NaCl Solution  

NASA Astrophysics Data System (ADS)

The enthalpies of dissolution of oxymatrine in 0.9%NaCl solution were measured using a RD496-2000 Calvet Microcalorimeter at 309.65 K under atmospheric pressure. The differential enthalpy and molar enthalpy of oxymatrine dissolution in the 0.9%NaCl solution of were determined. The corresponding kinetic equation that described the dissolution process was elucidated. Moreover, the half-life, molar entropy, molar enthaply, and Gibbs free energy of the dissolution process were also obtained.

Li, Zong-xiao; Pu, Xiao-hua; Zhao, Wei-wei; Chen, Yan

2011-02-01

286

Kinetics of 9-aminoacridine block of single Na channels  

PubMed Central

The kinetics of 9-aminoacridine (9-AA) block of single Na channels in neuroblastoma N1E-115 cells were studied using the gigohm seal, patch clamp technique, under the condition in which the Na current inactivation had been eliminated by treatment with N-bromoacetamide (NBA). Following NBA treatment, the current flowing through individual Na channels was manifested by square-wave open events lasting from several to tens of milliseconds. When 9-AA was applied to the cytoplasmic face of Na channels at concentrations ranging from 30 to 100 microM, it caused repetitive rapid transitions (flickering) between open and blocked states within single openings of Na channels, without affecting the amplitude of the single channel current. The histograms for the duration of blocked states and the histograms for the duration of open states could be fitted with a single-exponential function. The mean open time (tau o) became shorter as the drug concentration was increased, while the mean blocked time (tau b) was concentration independent. The association (blocking) rate constant, kappa, calculated from the slope of the curve relating the reciprocal mean open time to 9-AA concentration, showed little voltage dependence, the rate constant being on the order of 1 X 10(7) M-1s-1. The dissociation (unblocking) rate constant, l, calculated from the mean blocked time, was strongly voltage dependent, the mean rate constant being 214 s-1 at 0 mV and becoming larger as the membrane being hyperpolarized. The voltage dependence suggests that a first-order blocking site is located at least 63% of the way through the membrane field from the cytoplasmic surface. The equilibrium dissociation constant for 9-AA to block the Na channel, defined by the relation of l/kappa, was calculated to be 21 microM at 0 mV. Both tau -1o and tau -1b had a Q10 of 1.3, which suggests that binding reaction was diffusion controlled. The burst time in the presence of 9-AA, which is the sum of open times and blocked times, was longer than the lifetime of open channels in the absence of drug. All of the features of 9-AA block of single Na channels are compatible with the sequential model in which 9-AA molecules block open Na channels, and the blocked channels could not close until 9-AA molecules had left the blocking site in the channels.

1984-01-01

287

Discrete breathers in crystals with the NaCl structure  

NASA Astrophysics Data System (ADS)

In the recent decade, the spatially localized large-amplitude vibrational modes in defect-free crystals, referred to as discrete breathers (DBs), are intensively investigated in the materials science. This review reports the main results on gap DBs in crystals with the NaCl structure. The experimental proof of their existence in a NaI crystal is described. A number of molecular dynamics simulation results are presented, including new so far unpublished data. The properties of crystals potentially affected by the DBs are discussed.

Baimova, J. A.; Dmitriev, S. V.; Kistanov, A. A.; Potekaev, A. I.

2013-07-01

288

Russian Scientific-Educational Project: Kazan-GeoNa-2017  

NASA Astrophysics Data System (ADS)

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

Gusev, A.; Alibekova, N.

2012-09-01

289

Molecular dynamics simulation of dipalmitoylphosphatidylserine bilayer with Na+ counterions.  

PubMed Central

We performed a molecular dynamics simulation of dipalmitoylphosphatidylserine (DPPS) bilayer with Na+ counterions. We found that hydrogen bonding between the NH group and the phosphate group leads to a reduction in the area per headgroup when compared to the area in dipalmitoylphosphatidylcholine bilayer. The Na+ ions bind to the oxygen in the carboxyl group of serine, thus giving rise to a dipolar bilayer similar to dipalmitoylphosphatidylethanolamine bilayer. The results of the simulation show that counterions play a crucial role in determining the structural and electrostatic properties of DPPS bilayer.

Pandit, Sagar A; Berkowitz, Max L

2002-01-01

290

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

291

Structural transitions in NaCN and KCN  

NASA Astrophysics Data System (ADS)

An account is presented of our studies of the order-disorder phase transitions in NaCN and KCN. These are based on parameter-free inter-ionic potentials based on the Gordon-Kim modified electron gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and reproduced two transitions known in each of these systems. We also calculated upper bounds to the barrier of rotation of a cyanide ion in a ground state of NaCN and KCN and discuss possible shortcomings of our model. .

Ossowski, M. M.; Hardy, J. R.; Smith, R. W.

2000-09-01

292

ARUPS Study of Na on MoS2  

NASA Astrophysics Data System (ADS)

Angle-resolved ultraviolet photoemission spectroscopy was used to investigate the changes to a MoS2 (0002) surface due to the deposition of a thin overlayer of Na. The Na atoms donate an electron to the MoS2 crystal creating a new density of states above the valance band maximum of the bare crystal. The work function of the crystal was found to decrease with the addition of this electron. The experimental results were compared with a theoretical model based on FLAPW-DFT and showed in good agreement.

Jayasinghe, Aroshan; Park, Kenneth; Ellis, Trinity; Manandhar, Kedar; Hulbert, Steven; Ulrich, Marc; Rowe, Jack

2004-10-01

293

ADP+orthophosphate (P(i)) stimulates an Na\\/K pump-mediated coefflux of P(i) and Na in human red blood cell ghosts  

Microsoft Academic Search

The Na\\/K pump in human red blood cells that normally exchanges 3 Nai for 2 Ko is known to continue to transport Na in a ouabain-sensitive and ATP-dependent manner when the medium is made free of both Nao and Ko. Although this Na efflux is called \\

R. Marin

1994-01-01

294

Na+ conductivity of the Na+-driven flagellar motor complex composed of unplugged wild-type or mutant PomB with PomA.  

PubMed

PomA and PomB form the stator complex, which functions as a Na(+) channel, in the Na(+)-driven flagellar motor of Vibrio alginolyticus. The plug region of PomB is thought to regulate the Na(+) flow and to suppress massive ion influx through the stator channel. In this study, in order to measure the Na(+) conductivity of the unplugged stator, we over-produced a plug-deleted stator of the Na(+)-driven flagellar motor in Escherichia coli. The over-production of the plug-deleted stator in E. coli cells caused more severe growth inhibition than in Vibrio cells and that growth inhibition depended on the Na(+) concentration in the growth medium. Measurement of intracellular Na(+) concentration by flame photometry and fluorescent analysis with a Na(+) indicator, Sodium Green, revealed that over-production of the plug-deleted stator increased the Na(+) concentration in cell. Some mutations in the channel region of PomB or in the cytoplasmic region of PomA suppressed both the growth inhibition and the increase in intracellular Na(+) concentration. These results suggest that the level of growth inhibition correlates with the intracellular Na(+) concentration, probably due to the Na(+) conductivity through the stator due to the mutations. PMID:23420849

Takekawa, Norihiro; Terauchi, Takashi; Morimoto, Yusuke V; Minamino, Tohru; Lo, Chien-Jung; Kojima, Seiji; Homma, Michio

2013-02-18

295

The relation between plasma Na concentration and salt gland Na?K ATPase content in the diamondback terrapin and the yellow-bellied sea snake  

Microsoft Academic Search

The Na-K ATPase activity of the diamondback terrapin (Malaclemys) lachrymal salt gland increased with a rise in Na concentration of the plasma. Considerable dehydration was necessary to obtain maximal stimulation of gland Na-K ATPase and some terrapins kept in sea water for many months may not have fully active glands. No changes occurred in lachrymal gland weight. The salt glands

Margaret K. Dunson; William A. Dunson

1975-01-01

296

The loss of Na and Cl during the pyrolysis of a NaCl-loaded brown coal sample  

SciTech Connect

A Victorian brown coal was physically loaded with NaCl and pyrolyzed in a quartz fluidized-bed reactor. The fluidized-bed reactor was equipped with a quartz frit in the freeboard zone to enable the total devolatilization of the coal particles. The introduction of NaCl into the coal has caused only minor reductions in the weight loss. A significant amount of chlorine was volatilized during pyrolysis at temperatures as low as 200 C. At temperatures around 400--500 C where the loss of sodium was not very significant, about 70% of chlorine was volatilized from the coal particles. With the volatilization of chlorine at this temperature level, sodium must have been bonded to the char matrix. With increasing temperature, the volatilization of chlorine decreased and then increased again, whereas the volatilization of sodium increased monotonically with increasing temperature. Almost all the Na in coal could be volatilized at temperatures higher than about 800 C. These experimental results clearly indicate that chlorine and Na interacted strongly with coal/char at high temperatures. Na and Cl in the coal did not volatilize as NaCl molecules. Significant amounts of species containing a COO-group such as acetate, formate and oxalate were observed in the pyrolysis products although the exact forms of these species (i.e., as acids, salts or esters) in the pyrolysis product remain unknown. The yields of the species containing a COO-group decreased with increasing temperature, possibly due to the intensified thermal cracking reactions at high temperatures.

Mody, D.; Li, C.Z.

1999-07-01

297

Rate coefficient for the chemi-ionization in slow Li*(n)+Li and Na*(n)+Na collisions  

SciTech Connect

The chemi-ionization processes in slow-atom-Rydberg-atom collisions are considered in this paper. A version of the semiclassical method of rate coefficient calculation that is free of the presumptions which significantly limited its applicability previously is presented. The method is applied to the cases of Li*(n)+Li and Na*(n)+Na collisions for the principal quantum numbers 5{<=}n{<=}25 and temperatures 600{<=}T{<=}1200 K. The results of calculation of the rate coefficients of the corresponding chemi-ionization processes are compared to the existing experimental data from the literature.

Ignjatovic, Lj.M.; Mihajlov, A.A. [Institute of Physics, P. O. Box 68, 11080 Zemun, Belgrade (Serbia and Montenegro)

2005-08-15

298

Magnetic structure and properties of NaFeSO4F and NaCoSO4F  

NASA Astrophysics Data System (ADS)

NaFeSO4F and NaCoSO4F crystallize in the maxwellite crystal structure and consist of one-dimensional chains of corner-sharing MO4F2 octahedra linked together through F atoms sitting in a trans configuration with respect to each other. Magnetic susceptibility measurements and low-temperature powder neutron diffraction indicate that both the Fe- and Co-based phases establish G-type antiferromagnetic ground states below 36 and 29 K, respectively. We discuss the obtained magnetic structure in the context of the local anisotropy of the two magnetic ions.

Melot, B. C.; Rousse, G.; Chotard, J.-N.; Kemei, M. C.; Rodríguez-Carvajal, J.; Tarascon, J.-M.

2012-03-01

299

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

300

Luminescence Properties and Analytical Figures of Merits of Benzo(a)Pyrene Guanosine Adduct Adsorbed on ?- ?- and ?-Cyclodextrin\\/NaCl, and Trehalose\\/NaCl Solid Matrices  

Microsoft Academic Search

Several cyclodextrin\\/NaCl and trehalose\\/NaCl mixtures were investigated as solid matrices for obtaining room-temperature luminescence from a benzo(a)pyrene (B(a)P) guanosine adduct. Room-temperature fluorescence (RTF) and room-temperature phosphorescence (RTP) intensities from the B(a)P-guanosine adduct were compared for different solid matrices. These results showed that 25% trehalose\\/NaCl, 1% ?-cyclodextrin\\/NaCl, and 1% ?-cyclodextrin\\/NaCl solid matrices yielded strong fluorescence signals and moderately strong phosphorescence signals

Yu Chu; Robert J. Hurtubise

1993-01-01

301

Jejunal epithelial glucose metabolism: effects of Na+ replacement.  

PubMed

The objective of this study was to characterize the effects of replacement of extracellular Na+ with a nontransportable cation, N-methyl-D-glucamine (NMDG+) on jejunal epithelial glucose metabolism. Jejunal epithelium isolated from male Sprague-Dawley rats was incubated in media containing 5 mM glucose, 0.5 mM glutamine, 0.5 mM beta-hydroxybutyrate, and 0.3 mM acetoacetate as the principal carbon sources. O2 consumption and total glucose utilization were reduced 30 and 50%, respectively, when Na+ was replaced with NMDG+. In both media, approximately 75% of utilized glucose carbon was converted to lactate. The rate of glucose metabolism via the hexose monophosphate shunt, as evaluated using specific 14CO2 yields from [1-14C]glucose and [6-14C]glucose, was not appreciably altered by Na+ replacement. Tricarboxylic acid (TCA) cycle flux was evaluated using 14CO2 production from [14C]glucose and [14C]pyruvate radioisotopes. Approximately 50% of TCA cycle flux was shunted into products other than CO2 in both media. The majority of the acetyl-CoA oxidized in the TCA cycle was derived from cytosolic pyruvate. It is concluded that removal of Na+ from the bathing medium substantially reduced glucose utilization via the Embden-Meyerhof pathway and TCA cycle in the jejunal epithelium. PMID:3777159

Mallet, R T; Jackson, M J; Kelleher, J K

1986-11-01

302

Altered erythrocyte Na-K pump in anorectic patients  

SciTech Connect

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

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

1985-07-01

303

High Temperature Performance of NaI(Tl) Detector.  

National Technical Information Service (NTIS)

The response of NaI(TI) has been studied in the temperature range 300-375deg K. The dependence of pulse height and counting efficiency on activator concentration and temperature has been investigated. The pulse height has a negative temperature coefficien...

S. C. Sabharwal B. Ghosh R. Y. Deshpande M. R. Phiske M. P. Navalkar

1979-01-01

304

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

305

Results from CERN experiment NA36 on strangeness production  

SciTech Connect

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

NA36 Collaboration

1991-12-01

306

Mesospheric Na layer at extreme high latitudes in summer  

Microsoft Academic Search

Summertime observations of the mesospheric Na layer at high latitudes are reported from the 1993 Airbome Noctilucent Cloud (ANLC-93) campaign in the Canadian Arctic and at the Amundsen-Scott South Pole Station. Measurements at the South Pole reveal a layer that has a smaller column abundance and is significantly higher and thinner than at midlatitudes. Using a model that was essentially

John M. C. Plane; Rachel M. Cox; Jun Qian; William M. Pfenninger; George C. Papen; Chester S. Gardner; Patrick J. Espy

1998-01-01

307

Direct sublimation of NaCl salt from carbon matrixes.  

National Technical Information Service (NTIS)

This report provides the theoretical groundwork for the design and operation of a system for sublimation of NaCl from carbon matrixes. The findings and recommendations summarized below are based on the results of computer modeling of momentum, heat and ma...

Y. Zundelevich

1990-01-01

308

Selection of a NaCl-tolerant Citrus plant  

Microsoft Academic Search

Summary  The objective of the work was to select Citrus plants more tolerant to elevated NaCl concentrations in the irrigation water. For this purpose, unfertilized Troyer citrange ovules treated with a chemical mutagenic agent (ethyl methane sulphonate) were cultured in vitro. Whole plants were regenerated from embryos developed in the nucellar tissue of the ovule. The screening for salt tolerance was

Pilar García-Agustín; Eduardo Primo-Millo

1995-01-01

309

Escola na Rede:construindo uma comunidade eletrônica de aprendizagem  

Microsoft Academic Search

This paper aims to present the environment of the distance education program, named Escola na Rede, o f t he Secretaria da Fazenda do Rio Grande do Su l, Brasil (SEFA\\/RS), developed by Escola Fazendária (EFAZ). This tool was completely designed and developed , as an o wner s ystem, to supply not only the SEFA\\/RS corporative qualification needs, but

Fernanda Carneiro; Leão Gonçalves; Bayardo Joaquin; Vega Morales

310

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

311

Hemorragia intracraniana na gravidez e puerpério: experiência com quinze casos  

Microsoft Academic Search

RESUMO - A hemorragia intracraniana que acontece na gravidez é um fenômeno raro, porém, apresenta mortalidade e morbidades elevadas. Analisamos 15 pacientes com hemorragia intracraniana que ocorreu durante a gravidez ou puerpério. Em cinco casos a hemorragia decorria da ruptura de aneurisma, em 6, de malformação. A mortalidade materna foi 20%, e a fetal 33%. Quando a causa do sangramento

Jose Carlos Lynch; Ricardo Andrade; Celestino Pereira

2002-01-01

312

Polishing large NaCl windows on a continuous polisher  

Microsoft Academic Search

The Helios and Antares CO fusion laser systems incorporate numerous large sodium chloride windows. These must be refinished periodically, making necessary a consistent and predictable polishing capability. A continuous polisher (or annular lap) which might at Kirtland's Developmental Optical Facility. Large NaCl windows had not been polished on this type of machine. The machine has proven itself capable of producing

1979-01-01

313

The ins and outs of Na(+) bioenergetics in Acetobacterium woodii.  

PubMed

The acetogenic bacterium Acetobacterium woodii uses a transmembrane electrochemical sodium ion potential for bioenergetic reactions. A primary sodium ion potential is established during carbonate (acetogenesis) as well as caffeate respiration. The electrogenic Na(+) pump connected to the Wood-Ljungdahl pathway (acetogenesis) still remains to be identified. The pathway of caffeate reduction with hydrogen as electron donor was investigated and the only membrane-bound activity was found to be a ferredoxin-dependent NAD(+) reduction. This exergonic electron transfer reaction may be catalyzed by the membrane-bound Rnf complex that was discovered recently and is suggested to couple exergonic electron transfer from ferredoxin to NAD(+) to the vectorial transport of Na(+) across the cytoplasmic membrane. Rnf may also be involved in acetogenesis. The electrochemical sodium ion potential thus generated is used to drive endergonic reactions such as flagellar rotation and ATP synthesis. The ATP synthase is a member of the F(1)F(O) class of enzymes but has an unusual and exceptional feature. Its membrane-embedded rotor is a hybrid made of F(O) and V(O)-like subunits in a stoichiometry of 9:1. This stoichiometry is apparently not variable with the growth conditions. The structure and function of the Rnf complex and the Na(+) F(1)F(O) ATP synthase as key elements of the Na(+) cycle in A. woodii are discussed. PMID:19167341

Schmidt, Silke; Biegel, Eva; Müller, Volker

2009-01-08

314

Stimulated formation of ultracold ground (NaCa)^+ molecular ions  

Microsoft Academic Search

Ultracold atomic systems in which electric charges play an important role are of particular interest. Futhermore, the recently proposed possibility of sympathetic cooling of ions by cold neutral atoms in the same trap has opened the way to new fundamental collision process studies [1]. We theoretically study the possibility of forming ultracold ground (NaCa)^+ molecular ions starting with a Ca^+

Philippe Pellegrini; Harvey Michels; Winthrop Smith; Robin Coté

2006-01-01

315

TEMPORALIDADE E POLÍTICA NA LITERATURA APOCALÍPTICA JUDAICA 1  

Microsoft Academic Search

Resumo Existem dois tipos de textos apocalípticos: os de orientação histórica que descrevem um julgamento de proporções cósmicas (Daniel, por exemplo) e as viagens celestiais que se centram no destino da alma após a morte (2 Enoch ou 3 Baruch). Este artigo se concentrará na investigação dos apocalipses histórico\\/cósmicos, primariamente nos textos judaicos, mas também no Livro de Apocalipse, que

John J. Collins

2005-01-01

316

The drift chamber electronics for the NA48 experiment  

Microsoft Academic Search

Drift chamber readout electronics for over 8000 channels with concurrent data recording and readout have been developed to update the NA48 experiment existing system. Drift times are measured in bins of 1.56 ns with respect to the continuously running 40 MHz experiment clock. The architecture is based on commercially available hardware for cost effectiveness and flexibility. The design of the

Roberta Arcidiacono; Nicolo Cartiglia; Stefano Chiozzi; Marco Clemencic; Angelo Cotta Ramusino; Chiara Damiani; Alberto Gianoli; Roberto Malaguti; Ferruccio Petrucci; Marcella Scarpa

2004-01-01

317

Superionicity in Na3 PO4 : A molecular dynamics simulation  

Microsoft Academic Search

Fast ionic conduction in solid Na3PO4 is studied by use of molecular dynamics simulation based on the modified Lu -Hardy approach. We obtain reasonable agreement with experiment for the structural transition and diffusion of the sodium ions. All the sodium ions are found to contribute comparably to the high ionic conductivity. The results of the simulation are discussed in terms

Wei-Guo Yin; Jianjun Liu; Chun-Gang Duan; Wai-Ning Mei; Robert W. Smith; John R. Hardy

2004-01-01

318

Search for Na+ Pickup Ion Generated Waves at Mercury  

Microsoft Academic Search

Telescopic observations by Potter et al. [2002] have discovered that Mercury's Sodium exosphere has a tail extending 10's of Mercury radii. Theory predicts that the shape of and the amount of Sodium [Smyth, 1986, 1995; Ip 1986, 1990] in this exospheric tail is highly dependent upon the true anomaly of Mercury. The exospheric Na that is not reabsorbed on Mercury's

S. A. Boardsen; J. A. Slavin

2007-01-01

319

Search for Na+ Pickup Ion Generated Waves at Mercury  

NASA Astrophysics Data System (ADS)

Telescopic observations by Potter et al. [2002] have discovered that Mercury's Sodium exosphere has a tail extending 10's of Mercury radii. Theory predicts that the shape of and the amount of Sodium [Smyth, 1986, 1995; Ip 1986, 1990] in this exospheric tail is highly dependent upon the true anomaly of Mercury. The exospheric Na that is not reabsorbed on Mercury's surface will be photo-ionized. Computations by Ip [1986] indicated that ionized exospheric Na could significantly mass load the plasma population in Mercury's magnetosphere. These freshly created ions will be rapidly energized by the convection electric field in Mercury's magnetosphere and sheath and should be highly unstable to the generation of plasma waves. These waves could play an important role in the thermalization and retention of the Na+. Because the gyro radii of Na+ can be comparable to the scale sizes in Mercury's geospace there is an open question whether Mercury's geospace can sustain such waves. After a brief review of what was observed in the Mariner 10 magnetometer data, we will present analytic calculations of the expected pickup ion distributions, the expected unstable waves, their frequencies, wavelengths and Doppler shifts, their variation with location in Mercury's geospace and Mercury's true anomaly for both high and low solar wind convection electric fields. We will assess if and when such waves can be generated and sustained.

Boardsen, S. A.; Slavin, J. A.

2007-05-01

320

Tubuloglomerular Feedback: Effect of Dietary NaCl Intake.  

National Technical Information Service (NTIS)

It has been suggested that tubuloglomerular feedback (TGF), a mechanism that relates changes in single-nephron glomerular filtration rate (SNGFR) to alterations in a tubule fluid signal at the macula densa, may be modified by the dietary NaCl intake of th...

J. S. Kaufman R. J. Hamburger W. Flamenbaum

1976-01-01

321

Na + :HCO 3 ? Cotransporters (NBC): Cloning and Characterization  

Microsoft Academic Search

The sodium bicarbonate cotransporter (NBC1) is essential for bicarbonate transport across plasma mem- branes in epithelial and nonepithelial cells. The direction of the NaHCO3 movement in secretory epithelia is op- posite to that in reabsorptive epithelia. In secretory epi- thelia (such as pancreatic duct cells) NBC is responsible for the transport of bicarbonate from blood to the cell for eventual

M. Soleimani; C. E. Burnham

2001-01-01

322

Particle spectra and HBT results from NA44  

SciTech Connect

Recent results on baryon spectra and interferometry from NA44 are compared to RQMD and a hydrodynamical model. The importance of flow and rescattering on the rapidity and transverse mass distributions is discussed. The yields of protons and antiprotons are compared as a function of system, rapidity and multiplicity. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

Michael Murray for The NA44 Collaboration

1995-07-20

323

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.

Bobulescu, I. Alexandru

2010-01-01

324

Thermodynamics of the system NaCl-AlCl3  

NASA Astrophysics Data System (ADS)

Heat capacities of melts were measured in the range 400 to 1100 K and 0.48 < NAlCl3 < 0.62, the results being expressed by Cp = 40.96 0.0295 T + 2.01 × 10-5 T 2 J K-1 g·atom-1 i.e., AlCl3 contains 4 atoms, and so forth). This equation was used in interpreting literature vapor pressure data. Measurements were made of the emf of the concentration cell 11663_2007_Article_BF02654140_TeX2GIFE1.gif ALleft| {_{AlCl_3 }^{NACl(sat)} } right.left| {_{(Na^ + )}^{Pyrex} } right.left| {_{AlCl_3 }^{NACl(sat)} } right.left| {_{AlCl_3 }^{NACl} } right.left| {AL} right. at temperatures 473 to 623 K, and the results were correlated with the vapor pressure data to yield activities of NaCl and AlCl3. Measurements with a sodium electrode confirmed the accepted values for the free energy of formation of A1C13 within about 1.5 kJ mol-1. The activities were used to analyze the phase diagram. Direct measurement of the eutectic temperature with a concentration-cell technique (which avoids supercooling) gave 386 K; the eutectic composition is 60.0 mol pct A1C13. The standard entropy of NaAlCl4(s) is S{298.15/°} = 199.1 J K-1 mol-1. The free energy for NaAlCl4(l) = NaAlCl4(g) is ?G° = 82740 -63.66T J mol-1 at around 950 K.

Dewing, E. W.

1981-12-01

325

Microscopic solvation of NaBO2 in water: anion photoelectron spectroscopy and ab initio calculations.  

PubMed

We investigated the microscopic solvation of NaBO(2) in water by conducting photoelectron spectroscopy and ab initio studies on NaBO(2)(-)(H(2)O)(n) (n = 0-4) clusters. The vertical detachment energy (VDE) of NaBO(2)(-) is estimated to be 1.00 ± 0.08 eV. The photoelectron spectra of NaBO(2)(-)(H(2)O)(1) and NaBO(2)(-)(H(2)O)(2) are similar to that of bare NaBO(2)(-), except that their VDEs shift to higher electron binding energies (EBE). For the spectra of NaBO(2)(-)(H(2)O)(3) and NaBO(2)(-)(H(2)O)(4), a low EBE feature appears dramatically in addition to the features observed in the spectra of NaBO(2)(-)(H(2)O)(0-2). Our study shows that the water molecules mainly interact with the BO(2)(-) unit in NaBO(2)(-)(H(2)O)(1) and NaBO(2)(-)(H(2)O)(2) clusters to form Na-BO(2)(-)(H(2)O)(n) type structures, while in NaBO(2)(-)(H(2)O)(3) and NaBO(2)(-)(H(2)O)(4) clusters, the water molecules can interact strongly with the Na atom, therefore, the Na-BO(2)(-)(H(2)O)(n) and Na(H(2)O)(n)···BO(2)(-) types of structures coexist. That can be seen as an initial step of the transition from a contact ion pair (CIP) structure to a solvent-separated ion pair (SSIP) structure for the dissolution of NaBO(2). PMID:21814667

Feng, Yuan; Cheng, Min; Kong, Xiang-Yu; Xu, Hong-Guang; Zheng, Wei-Jun

2011-08-03

326

Inhibition of voltage-gated Na(+) current by nanosecond pulsed electric field (nsPEF) is not mediated by Na(+) influx or Ca(2+) signaling.  

PubMed

In earlier studies, we found that permeabilization of mammalian cells with nsPEF was accompanied by prolonged inhibition of voltage-gated (VG) currents through the plasma membrane. This study explored if the inhibition of VG Na(+) current (I(Na)) resulted from (i) reduction of the transmembrane Na(+) gradient due to its influx via nsPEF-opened pores, and/or (ii) downregulation of the VG channels by a Ca(2+)-dependent mechanism. We found that a single 300 ns electric pulse at 1.6-5.3 kV/cm triggered sustained Na(+) influx in exposed NG108 cells and in primary chromaffin cells, as detected by increased fluorescence of a Sodium Green Dye. In the whole-cell patch clamp configuration, this influx was efficiently buffered by the pipette solution so that the increase in the intracellular concentration of Na(+) ([Na](i)) did not exceed 2-3 mM. [Na](i) increased uniformly over the cell volume and showed no additional peaks immediately below the plasma membrane. Concurrently, nsPEF reduced VG I(Na) by 30-60% (at 4 and 5.3 kV/cm). In control experiments, even a greater increase of the pipette [Na(+)] (by 5 mM) did not attenuate VG I(Na), thereby indicating that the nsPEF-induced Na(+) influx was not the cause of VG I(Na) inhibition. Similarly, adding 20 mM of a fast Ca(2+) chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) into the pipette solution did not prevent or attenuate the inhibition of the VG I(Na) by nsPEF. These findings point to possible Ca(2+)-independent downregulation of the VG Na(+) channels (e.g., caused by alteration of the lipid bilayer) or the direct effect of nsPEF on the channel. PMID:22234846

Nesin, Vasyl; Pakhomov, Andrei G

2012-01-10

327

Radiation damage in NaCl: General model of nucleation and aggregation processes in doped NaCl  

Microsoft Academic Search

The model presented here offers an extensive description of the nucleation and aggregation processes in irradiated NaCl. In particular the effect of impurities on the production of radiation damage has been studied. As compared to theoretical models in the literature the approach shows the following refinements:(1) The nucleation behaviour for aggregation of primary defects is included. Dislocation loops are formed

J. Seinen; J. C. Groote; J. R. W. Weerkamp; H. W. Den Hartog

1992-01-01

328

Radiation damage in NaCl: General model of nucleation and aggregation processes in doped NaCl  

Microsoft Academic Search

The model presented here offers an extensive description of the nucleation and aggregation processes in irradiated NaCl. In particular the effect of impurities on the production of radiation damage has been studied. As compared to theoretical models in the literature the approach shows the following refinements: (1) The nucleation behaviour for aggregation of primary defects is included. Dislocation loops are

J. Seinen; J. C. Groote; J. R. W. Weerkamp; H. W. den Hartog

1992-01-01

329

Identification and characterization of a NaCl-inducible vacuolar Na+/H+ antiporter in Beta vulgaris.  

PubMed

We have cloned, by RT-PCR and the use of degenerate oligonucleotide primers, a Na+/H+ antiporter from Beta vulgaris that is homologous to NHX1 of Arabidopsis thaliana and is a member of the family of recently cloned plant NHX-genes. This antiporter, BvNHX1, partially complements the salt-sensitive phenotype of a Deltaena1-4Deltanhx1 yeast strain. Antibodies were raised against a central portion of the BvNHX1 open reading frame that was predicted from the cloned cDNA. This antiporter was found to be highly enriched in tonoplast membranes isolated from plant tissues. BvNHX1 transcript abundance increased after salt treatments, in both suspension-cell cultures and whole plants. BvNHX1 protein abundance in the tonoplast-enriched membranes was also elevated after salt treatments. The vacuolar Na+/H+ antiporter activity increased up to 3-fold when the cell were exposed to 100 mM NaCl. The increase in protein abundance in response to the salt treatment, together with the salt-induced vacuolar Na+/H+ antiporter activity in B. vulgaris suggests that BvNHX1 plays an important role in salinity tolerance. PMID:12354197

Xia, Tao; Apse, Maris P.; Aharon, Gilad S.; Blumwald, Eduardo

2002-10-01

330

3% NaCl and 7.5% NaCl/dextran 70 in the resuscitation of severely injured patients.  

PubMed Central

Cardiovascular resuscitation of the severely injured patient in the field remains unsatisfactory because large volumes of intravenous fluid are needed to keep up with ongoing blood losses and because only small volumes of fluid can be given. In the first study reported here, small volumes (less than or equal to 12 mL/kg) of 3% NaCl were given to patients who were having surgery for severe injuries. The 3% NaCl restored blood pressure, pH, and urine output with approximately one half of the cumulative fluid requirement of patients who received isotonic fluids (p less than 0.05). In a second study, 7.5% NaCl/dextran 70, 250 mL, was given in a prospective, randomized, and double-blinded trial to injured patients in the field. Blood pressure in the hypertonic/hyperoncotic group increased 49 mmHg during transport (p less than 0.005); blood pressure in patients given lactated Ringer's solution increased 19 mmHg (NS). Survival favored the hypertonic/hyperoncotic group. The 7.5% NaCl/dextran 70 solution appears particularly promising for treatment of injured patients in the field.

Holcroft, J W; Vassar, M J; Turner, J E; Derlet, R W; Kramer, G C

1987-01-01

331

Luminescence and energy migration in Ba 3NaNbO 6 and Ba 3NaTaO 6  

NASA Astrophysics Data System (ADS)

The luminescence of Ba 3NabO 6 and Ba 3NaTaO 6 is reported and discussed. These compounds contain isolated niobate and tantalate octahedra. They show an efficient photoluminescence at low temperatures. At room temperature this luminescence is quenched by energy migration. A comparison with physically similar systems is made.

Blasse, G.; Dirksen, G. J.; Zhiwu, Pei; Wehrum, G.; Hoppe, R.

1993-12-01

332

Gibbs ensemble Monte Carlo simulation of supercritical CO2 adsorption on NaA and NaX zeolites  

NASA Astrophysics Data System (ADS)

Adsorption of supercritical carbon dioxide on two kinds of zeolites with identical chemical composition but different pore structure (NaA and NaX) was studied using the Gibbs ensemble Monte Carlo simulation. The model frameworks for the two zeolites with Si/Al ratio being unity have been chosen as the solid structures in the simulation. The adsorption behaviors of supercritical CO2 on the NaA and NaX zeolites, based on the adsorption isotherms and isosteric heats of adsorption, were discussed in detail and were compared with the available experimental results. A good agreement between the simulated and experimental results is obtained for both the adsorbed amount and the bulk phase density. The intermediate configurational snapshots and the radial distribution functions between zeolite and adsorbed CO2 molecules were collected in order to investigate the preferable adsorption locations and the confined structure behavior of CO2. The structure behaviors of the adsorbed CO2 molecules show various performances, as compared with the bulk phase, due to the confined effect in the zeolite pores.

Liu, Shanshan; Yang, Xiaoning

2006-06-01

333

Na sup + pump in renal tubular cells is regulated by endogenous Na sup + -K sup + -ATPase inhibitor from hypothalamus  

SciTech Connect

Bovine hypothalamus contains a high affinity, specific, reversible inhibitor of mammalian Na{sup +}-K{sup +}-ATPase. Kinetic analysis using isolated membrane fractions showed binding and dissociation rates of the hypothalamic factor (HF) to be (like ouabain) relatively long (off rate = 60 min). To determine whether the kinetics of inhibition in intact cells might be more consistent with regulation of physiological processes in vivo, binding and dissociation reactions of HF in intact renal epithelial cells (LLC-PK{sup 1}) were studied using {sup 86}Rb{sup +} uptake and ({sup 3}H)ouabain binding. As with membranes, a 60-min incubation with HF inhibited Na{sup +}-K{sup +}-ATPase in LLC-PK{sub 1} cells. In contrast to membrane studies, no prolonged incubation with LLC-PK{sub 1} was needed to observe inhibition of Na{sup +}-K{sup +}-ATPase. HF caused a 33% inhibition of ouabain-sensitive {sup 86}Rb{sup +} influx within 10 min. Incubation of cells with HF followed by washout showed rapid reversal of pump inhibition and a doubling of pump activity. The dose-response curve for HF inhibition of LLC-PK{sub 1} {sup 86}Rb{sup +} uptake showed a sigmoidal shape consistent with an allosteric binding reaction. Thus HF is a potent regulator of Na{sup +}-K{sup +}-ATPase activity in intact renal cells, with binding and dissociation reactions consistent with relevant physiological processes.

Cantiello, H.F.; Chen, E.; Ray, S.; Haupert, G.T. Jr. (Harvard medical School, Boston, MA (USA))

1988-10-01

334

PPARgamma agonists do not directly enhance basal or insulin-stimulated Na(+) transport via the epithelial Na(+) channel.  

PubMed

Selective agonists of peroxisome proliferator-activated receptor gamma (PPARgamma) are anti-diabetic drugs that enhance cellular responsiveness to insulin. However, in some patients, fluid retention, plasma volume expansion, and edema have been observed. It is well established that insulin regulates Na(+) reabsorption via the epithelial sodium channel (ENaC) located in the distal tubule. Therefore, we hypothesized that these agonists may positively modulate insulin-stimulated ENaC activity leading to increased Na(+) reabsorption and fluid retention. Using electrophysiological techniques, dose-response curves for insulin-mediated Na(+) transport in the A6, M-1, and mpkCCD(cl4) cell lines were performed. Each line demonstrated hormone efficacy within physiological concentration ranges and, therefore, can be used to monitor clinically relevant effects of pharmacological agents which may affect electrolyte transport. Immunodetection and quantitative PCR analyses showed that each cell line expresses viable and functional PPARgamma receptors. Despite this finding, two PPARgamma agonists, pioglitazone and GW7845 did not directly enhance basal or insulin-stimulated Na(+) flux via ENaC, as shown by electrophysiological methodologies. These studies provide important results, which eliminate insulin-mediated ENaC activation as a candidate mechanism underlying the fluid retention observed with PPARgamma agonist use. PMID:16170524

Nofziger, Charity; Chen, Lihong; Shane, Michael Anne; Smith, Chari D; Brown, Kathleen K; Blazer-Yost, Bonnie L

2005-09-17

335

The Putative Plasma Membrane Na ? \\/HAntiporter SOS1 Controls Long-Distance NaTransport in Plants  

Microsoft Academic Search

The salt tolerance locus SOS1 from Arabidopsis has been shown to encode a putative plasma membrane Na ? \\/Hanti- porter. In this study, we examined the tissue-specific pattern of gene expression as well as the Natransport activity and subcellular localization of SOS1. When expressed in a yeast mutant deficient in endogenous Natransporters, SOS1 was able to reduce Naaccumulation and improve

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

336

Genetic Variation of the Alpha Subunit of the Epithelial Na+ Channels Influences Exhaled Na+ in Healthy Humans  

PubMed Central

Epithelial Na+ Channels (ENaC) are located on alveolar cells and are important in ?2-adrenergic receptor-mediated lung fluid clearance through the removal of Na+ from the alveolar airspace. Previous work has demonstrated that genetic variation of the alpha subunit of ENaC at amino acid 663 is important in channel function: cells with the genotype resulting in alanine at amino acid 663 (A663) demonstrate attenuated function when compared to genotypes with at least one allele encoding threonine (T663, AT/TT). We sought to determine the influence of genetic variation at position 663 of ENaC on exhaled Na+ in healthy humans. Exhaled Na+ was measured in 18 AA and 13 AT/TT subjects (age=27±8 vs. 30±10yrs., ht.=174±12 vs. 171±10cm., wt=68±12 vs. 73±14kg., BMI=22±3 vs. 25±4kg/m2, mean±SD, for AA and AT/TT, respectively). Measurements were made at baseline and at 30, 60 and 90 minutes following the administration of a nebulized ?2-agonist (albuterol sulfate, 2.5mg diluted in 3ml normal saline). The AA group had a higher baseline level of exhaled Na+ and a greater response to ?2-agonist stimulation (baseline= 3.1±1.8 vs. 2.3±1.5mmol/l; 30min-post= 2.1±0.7 vs. 2.2±0.8mmol/l; 60min-post= 2.0±0.5 vs. 2.3±1.0mmol/l; 90min-post= 1.8±0.8 vs. 2.6±1.5mmol/l, mean±SD, for AA and AT/TT, respectively, p<0.05). The results are consistent with the notion that genetic variation of ENaC influences ?2-adrenergic receptor stimulated Na+ clearance in the lungs, as there was a significant reduction in exhaled Na+ over time in the AA group.

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

2011-01-01

337

Effects of Exogenous Silicon on Germination Characteristics of Cucumber Seeds under NaHCO3 Stress  

Microsoft Academic Search

The germination characteristics of cucumber seeds were determined after treatments of as follows: (1) the control (CK): distilled water; (2) Na: 70 mmol•L-1 NaHCO3; (3) S1 + Na: 0.01 mmol•L-1 silicon + 70 mmol•L-1 NaHCO3; (4) S2 + Na: 0.1 mmol•L-1 silicon + 70 mmol•L-1 NaHCO3. The results showed that the germination rate, germination potential, germination index, growing vigor index,

Yongdong Sun; Weirong Luo; Wenjie Zhang; Xiumei Zhou

2010-01-01

338

Electrowinning of cobalt from a sulphate bath containing H 3 BO 3 and NaF  

Microsoft Academic Search

Electrowinning of cobalt from a sulphate bath containing Na2SO4, NaF and H3BO3 individually and H3BO3 in combination with NaF and Na2SO4 was studied. From the preliminary study it was observed that a sulphate bath containing both NaF and H3BO3 gave the best results. The effects of various parameters, namely NaF, H3BO3 and cobalt concentrations, current density, bath temperature, bath pH,

S. C. Das; T. Subbaiah

1987-01-01

339

Electron impact excitation and ionization of laser-excited Na atoms  

Microsoft Academic Search

Electron spectra for 1.5 keV electron impact on Na are measured for one-step laser excitation to Na(3p32) and for two-step laser excitation to Na(4d52) or Na(5s). Auger states Na+ (2s2p6nl) with nl=3p, 4p, 5p; 5s, 6s, 7s; 4d, 5d, 6d are observed, most of them cannot be reached by ionization of the ground state atom Na(3s). State energies, shake probabilities,

A. Dorn; C. Winnewisser; M. Wetzstein; J. Nienhaus; A. N. Grum-Grzhimailo; O. I. Zatsarinny; W. Mehlhorn

1995-01-01

340

Fast Na+ ion conductivity in glass, intermediate and crystalline phases of Na4UO2(SO4)3  

NASA Astrophysics Data System (ADS)

The ac electrical conductivity, DSC calorimetry and density data for pure Na4UO2(SO4)3 and for compound incorporating guest ions Rb+, Cd2+, Gd3+, SiO{4/4-}in the glass, quasi-crystalline intermediate and crystalline phases are reported. The glass phase conductivity data show an increase in Na+ conductivity by a factor ?103 relative to pure crystalline Na2SO4 in the low temperature (LT) region, i.e. 180°C. There is no onset of phase transition up to ˜260°C. The distinct conductivity regimes prior to devitrification in the glass suggest that higher energy or excited structural states/configurations can exist in the glass phase. The apparent activation energy Q c value 76±5 kJ/mole for the glass state of all compositions is in excellent agreement with the Na2SO4 III Q c value. The conductivity regime immediately after devitrification with Q c of 40±3 kJ/mole represents the stable intermediate phase. The conductivity of the final product of devitrification on cooling resembles crystalline behavior except for (Na3.5Rb0.5)UO2(SO4)3. A gradual jump in conductivity accompanies the ??? transition in the crystalline sample. The Q c value is 75±5 kJ/mole for the ?(HT) phase conductivity in the heating mode but remains constant at 66±5 kJ/mole for the ? (LT) phase in the heating mode and for both ? and ? phases in the cooling mode. The excellent conductivity-volume, i.e. ??/?V correlation is consistent with the “free” volume contribution to conductivity enhancement and the percolation-type mechanism of transport.

Gundusharma, U. M.; Secco, E. A.

1990-07-01

341

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

342

Relationship between functional Na+ pumps and mitogenesis in cultured coronary artery smooth muscle cells.  

PubMed

An increase in functional sarcolemmal Na(+)-K(+)-ATPase (Na+ pump) precedes proliferation in vascular smooth muscle cells (VSMCs) seeded in 10% fetal bovine serum (FBS), but its role in mitogenesis is unresolved. Enzymatically dispersed canine coronary artery VSMCs were seeded in FBS and studied through confluence. Before a shift in cell cycle (G1-->S, G2 + M) and appearance of the nonmuscle isoform of myosin (MHCnm), intracellular Na+ content (Na+i) and cell volume (CV) increased (day 0 through day 3). Na+ pump number ([3H]-ouabain binding) increased at day 4 followed by a decrease in Na+i and CV. When Na+ pumps were inhibited by the addition of ouabain to FBS, VSMCs were arrested in G1, and MHCnm was not upregulated. Na+i increased similarly to that in FBS but failed to correct to day 0 levels. Withdrawal of ouabain at day 4 in culture led to an increase in Na+ pump number, a decrease in Na+i, entry of cells into S and G2 + M, and upregulation of MHCnm. These data suggest that Na+i, phenotypic modulation, and entry of cells into the cell cycle are temporally related, with Na+ pump-mediated correction of increased Na+i as a key event in the VSMC mitogenic process. PMID:8381588

Feltes, T F; Seidel, C L; Dennison, D K; Amick, S; Allen, J C

1993-01-01

343

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

344

Investigation of sodium distribution in phosphate glasses using spin-echo {sup 23}Na NMR  

SciTech Connect

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

Alam, T.M.; McLaughlin, J.; Click, C.C.; Conzone, S.; Brow, R.K.; Boyle, T.J.; Zwanziger, J.W.

2000-02-24

345

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

SciTech Connect

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

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

1999-09-16

346

Molecular cloning and functional characterization of the Aplysia FMRFamide-gated Na+ channel.  

PubMed

FMRFamide-gated Na+ channel (FaNaC) is the only known peptide-gated ion channel, which belongs to the epithelial Na+ channel/degenerin (ENaC/DEG) family. We have cloned a putative FaNaC from the Aplysia kurodai CNS library using PCR, and examined its characteristics in Xenopus oocytes. A. kurodai FaNaC (AkFaNaC) comprised with 653 amino acids, and the sequence predicts two putative membrane domains and a large extracellular domain as in other members of the ENaC/DEG family. In oocytes expressing AkFaNaC, FMRFamide evoked amiloride-sensitive Na+ current. Different from the known FaNaCs (Helix and Helisoma FaNaCs), AkFaNaC was blocked by external Ca2+ but not by Mg2+. Also, desensitization of the current was enhanced by Mg2+ but not by Ca2+. The FMRFamide-gated current was depressed in both low and high pH. These results indicate that AkFaNaC is an FaNaC of Aplysia, and that the channel has Aplysia specific functional domains. PMID:16133260

Furukawa, Yasuo; Miyawaki, Yoshiyuki; Abe, Genbu

2005-08-23

347

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

348

Phospholemman Overexpression Inhibits Na+-K+-ATPase in Adult Rat Cardiac Myocytes: Relevance to Decreased Na+ pump Activity in Post-Infarction Myocytes  

PubMed Central

Messenger RNA levels of phospholemman (PLM), a member of the FXYD family of small single-span membrane proteins with putative ion-transport regulatory properties, were increased in postinfarction (MI) rat myocytes. We tested the hypothesis that the previously observed reduction in Na+-K+-ATPase activity in MI rat myocytes was due to PLM overexpression. In rat hearts harvested 3 and 7 days post-MI, PLM protein expression was increased by 2- and 4-fold, respectively. To simulate increased PLM expression post-MI, PLM was overexpressed in normal adult rat myocytes by adenovirus-mediated gene transfer. PLM overexpression did not affect the relative level of phosphorylation on serine68 of PLM. Na+-K+-ATPase activity was measured as ouabain-sensitive Na+-K+ pump current (Ip). Compared to control myocytes overexpressing green fluorescent protein alone, Ip measured in myocytes overexpressing PLM was significantly (P<0.0001) lower at similar membrane voltages, pipette Na+ ([Na+]pip) and extracellular K+ concentrations ([K+]o). From ?70 to +60 mV, neither [Na+]pip nor [K+]o required to attain half-maximal Ip was significantly different between control and PLM myocytes. This phenotype of decreased Vmax without appreciable changes in Km for Na+ and K+ in PLM overexpressed myocytes was similar to that observed in MI rat myocytes. Inhibition of Ip by PLM overexpression was not due to decreased Na+-K+-ATPase expression since there were no changes in either protein or messenger RNA levels of either ?1 or ?2 isoforms of Na+-K+-ATPase. In native rat cardiac myocytes, PLM co-immunoprecipitated with ?-subunits of Na+-K+-ATPase. Inhibition of Na+-K+-ATPase by PLM overexpression, in addition to previously reported decrease in Na+-K+-ATPase expression, may explain altered Vmax but not Km of Na+-K+-ATPase in postinfarction rat myocytes.

Zhang, Xue-Qian; Moorman, J. Randall; Ahlers, Belinda A.; Carl, Lois L.; Lake, Douglas E.; Song, Jianliang; Mounsey, J. Paul; Tucker, Amy L.; Chan, Yiu-mo; Rothblum, Lawrence I.; Stahl, Richard C.; Carey, David J.; Cheung, Joseph Y.

2005-01-01

349

Cobalt Hexacyanoferrate as Cathode Material for Na+ Secondary Battery  

NASA Astrophysics Data System (ADS)

We investigated structural and electrochemical properties of thin film electrodes of cobalt hexacyanoferrate, NaxCo[Fe(CN)6]0.902.9H2O, against x. The compound exhibits a high capacity of 135 mAh/g and an average operating voltage of 3.6 V against Na, with a good cyclability. The discharge curve exhibits two plateaus at ?3.8 and ?3.4 V, which are ascribed to the reduction processes of Fe3+ and Co3+, respectively. The ex situ X-ray diffraction (XRD) profiles reveal the robust nature of the host framework against Na+ intercalation/deintercalation. Thus, cobalt hexacyanoferrate is a promising candidate for the cathode material of sodium-ion secondary battery (SIB).

Takachi, Masamitsu; Matsuda, Tomoyuki; Moritomo, Yutaka

2013-02-01

350

Dissociation energy of the ground state of NaH  

NASA Astrophysics Data System (ADS)

The dissociation energy of the ground state of NaH was determined by analyzing the observed near dissociation rovibrational levels. These levels were reached by stimulated emission pumping and fluorescence depletion spectroscopy. A total of 114 rovibrational levels in the ranges 9<=v''<=21 and 1<=J''<=14 were assigned to the X 1?+ state of NaH. The highest vibrational level observed was only about 40 cm-1 from the dissociation limit in the ground state. One quasibound state, above the dissociation limit and confined by the centrifugal barrier, was observed. Determining the vibrational quantum number at dissociation vD from the highest four vibrational levels yielded the dissociation energy De=15 815+/-5 cm-1. Based on new observations and available data, a set of Dunham coefficients and the rotationless Rydberg-Klein-Rees curve were constructed. The effective potential curve and the quasibound states were discussed.

Huang, Hsien-Yu; Lu, Tsai-Lien; Whang, Thou-Jen; Chang, Yung-Yung; Tsai, Chin-Chun

2010-07-01

351

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

352

Co[sup 2+] ion exchange with NaY  

SciTech Connect

Co[sup 2+] ion exchange from aqueous cobalt chloride-sodium chloride solutions with NaY zeolite has been investigated. The effect of contact time on the sorption of Co[sup 2+] by dehydrated Y zeolite at 150[degrees]C is unusual. A fast sorption uptake is observed in which 1.73 mequiv/g of zeolite of Na[sup +] ions is replaced by cobalt ions, followed by a desorption process where the uptake decreases to 1.56 mequiv/g of zeolite. This behavior is explained by the location and coordination of cobalt in Y zeolite sites. It is suggested that the maximum uptake corresponds to cobalt ions being simultaneously in two sites; tetrahedrally coordinated in the sodalite units and octahedrally coordinated in the large cavities. It is also suggested that the desorption process is a consequence of a reaction between Cl[sup [minus

Garcia, I.; Solache-Rios, M.; Bulbulian, S. (Instituto Nacional de Investigaciones Nucleares, Mexico City (Mexico)); Bosch, P. (Instituto Nacional de Investigaciones Nucleares, Mexico City (Mexico) Universidad Autonoma Metropolitana, Iztapalapa (Mexico))

1993-02-11

353

23Na magnetic resonance imaging: distribution of brine in muscle.  

PubMed

Magnetic resonance imaging (MRI) has been used to characterize tissues in morphological studies. Here, 23Na NMR imaging was used to study the distribution in muscle of brine (5 M NaCl), injected before onset of rigor mortis. First, the distribution of brine was monitored in excised muscle from rabbits for 6 hr following arterial brine injection. Immediately after injection, distribution was clearly heterogeneous. After 6 hr, a steady state was achieved but the observed brine distribution was not fully homogeneous. Second, the same was done for ham processed in various ways (tumbling, cooking). Tumbling increased the homogeneity of distribution in our experimental conditions but only cooking afforded full homogenization of brine in ham. Concentrations of NMR-visible sodium in the muscles were appreciably lower than the expected values calculated from the volume of injected brine. The invisible sodium presumably has T2 values which are too short compared with the echo time in our conventional spectrometer. PMID:8295500

Renou, J P; Benderbous, S; Bielicki, G; Foucat, L; Donnat, J P

1994-01-01

354

Homeostatic function of astrocytes: Ca(2+) and Na(+) signalling.  

PubMed

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, Ca(2+) 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 Ca(2+) and Na(+) signalling. PMID:23243501

Parpura, Vladimir; Verkhratsky, Alexei

2012-12-01

355

Production technology of an electrolyte for Na/S batteries  

NASA Astrophysics Data System (ADS)

A production method for a ceramic electrolyte for Na/S batteries was developed. The ceramic materials are based on MgO and MgAl2O4 (spinel). A dense MgO-ceramic (purity 99.5%) shows no damage after 100 hr at 1500 C in an Na2O-vapor atmosphere. Cartridges with a sintered density 340 g/cc achieve 50 burn cycles. A small scale production line for 1000 cartrigdes with a monthly output of 250 parts is described. Variations of powder properties cause high scrap rates and a large variation of sintered densities. A short quality test based on internal pressure was devised. Compared with MgO the nonhygroscopic spinel has production advantages, but is expensive.

Mayer, H.; Reckziegel, A.

1984-12-01

356

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.

Parpura, Vladimir; Verkhratsky, Alexei

2012-01-01

357

Thermal Activation Energies in NaCl and KCl Crystals  

Microsoft Academic Search

Thermal activation energies were computed from various glow peaks of NaCl and KCl single crystals. The method developed in the preceding paper has been used successfully in these calculations. Good agreement was obtained with the results calculated from the initial rise of the glow peaks. Activation energies varied from 0.3 to 1.5 ev for various peaks in the glow curve

A. Halperin; A. A. Braner; A. Ben-Zvi; N. Kristianpoller

1960-01-01

358

Elastic Properties of NaCl: OH at Low Temperatures  

Microsoft Academic Search

Low temperature behavior of elastic constants (C11-C12)\\/2, C44 and C11 of NaCl crystals with OH impurity ions of various concentrations up to 650 ppm has been studied by means of an ultrasonic method. Pronounced softenings of the elastic constants below 50 K with minimum points around 0.8 K have been observed. The interaction between the elastic strain and the quadrupolar

Eizaburo Kanda; Terutaka Goto; Hiroshi Yamada; Shozo Suto; Satoshi Tanaka; Toshizo Fujita; Tadao Fujimura

1985-01-01

359

Interaction of NaCl with solid water  

Microsoft Academic Search

The interaction of NaCl with solid water, deposited on tungsten at 80 K, was investigated with metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS) (He I). We have studied the ionization of Cl(3p) and the 1b1, 3a1, and 1b2 bands of molecular water. The results are supplemented by first-principles density functional theory (DFT) calculations of the electronic structure

A. Borodin; O. Höfft; U. Kahnert; V. Kempter; A. Poddey; P. E. Blöchl

2004-01-01

360

Characterization of Gastric Na +\\/I ?Symporter of the Rat  

Microsoft Academic Search

Characterization of gastric Na+\\/I?symporter (NIS) of the rat was carried out. Sequencing of the open reading frame of gastric NIS mRNA showed only three nucleotide changes when compared with FRTL-5 NIS cDNA, and two of these changes led to amino acid changes. The results of Northern blot analysis showed that abundant NIS mRNA was expressed in the stomach when compared

Tomio Kotani; Yoshikazu Ogata; Ikuo Yamamoto; Yatsuki Aratake; Jun-Ichi Kawano; Tatsuo Suganuma; Sachiya Ohtaki

1998-01-01

361

NaCl doping and the conductivity of agar phantoms  

Microsoft Academic Search

A recipe for manipulating the conductivity of agar impedance-imaging phantoms through their NaCl (salt) content is reexamined. The conductivities at frequencies 100kHz and below are characterized for phantoms created with the recipe. The data are compared against the recipe's predictive formula for conductivity as a function of salt content. Based on analysis of the data a modified version of the

D. Bennett

2011-01-01

362

Compartmental aspects of Na + saturation kinetics in prog skin a  

Microsoft Academic Search

Epithelial membranes are multicompartment structures of microscopic and submicroscopic dimensions. Therefore, interpretations\\u000a of kinetic data on solute fluxes, based on the standard three compartment model are open to criticism. We have obtained an\\u000a integrated view of the kinetics of Na+ transport in frog skin epidermis by application of the computer simulation method. Epidermis and whole skin models were designed\\u000a which

Ernst G. Huf; John R. Howell

1979-01-01

363

Electrogenic NaCa exchange in retinal rod outer segment  

Microsoft Academic Search

Previous work has suggested that a Na-Ca exchanger may have a key role in visual transduction in retinal rods1-10. This exchanger is thought to maintain a low internal free Ca2+ concentration in darkness4-10 and to contribute to the rod's recovery after light by removing any internally released Ca2+ (refs 1, 2, 6-8). Little else is known about this transport mechanism

King-Wai Yau; Kei Nakatani

1984-01-01

364

Ionophoretic model for NaCa counter transport  

Microsoft Academic Search

IN most mammalian cells the cytosolic concentration of free ionised Ca2+ is thought to approximate 10-6-10-7 M, whereas the extracellular Ca2+ concentration is close to 10-3 M (ref. 1). The efflux of Ca2+ across the cell membrane, which takes place against an electrochemical gradient, is apparently mediated either by a Ca2+-stimulated ATPase2 or by a Na-Ca counter transport process. In

W. J. Malaisse; E. Couturier

1978-01-01

365

In-beam -ray spectroscopy of ³Mg and ³³Na  

Microsoft Academic Search

Excited states in the very neutron-rich nuclei ³Mg and ³³Na were populated in the fragmentation of a ³Si projectile beam on a Be target at 83 MeV\\/u beam energy. We report on the first observation of -ray transitions in ³Mg, the odd-N neighbor of ³Mg and ³Mg, which are known to be part of the 'island of inversion' around N=20.

A. Gade; B. A. Brown; C. M. Campbell; J. M. Cook; T. Glasmacher; S. McDaniel; A. Ratkiewicz; J. R. Terry; D. Bazin; S. Ettenauer; A. Obertelli; D. Weisshaar; K. W. Kemper; T. Otsuka; Y. Utsuno

2011-01-01

366

The Offline Software Framework of the NA61/SHINE Experiment  

NASA Astrophysics Data System (ADS)

NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) is an experiment at the CERN SPS using the upgraded NA49 hadron spectrometer. Among its physics goals are precise hadron production measurements for improving calculations of the neutrino beam flux in the T2K neutrino oscillation experiment as well as for more reliable simulations of cosmic-ray air showers. Moreover, p+p, p+Pb and nucleus+nucleus collisions will be studied extensively to allow for a study of properties of the onset of deconfinement and search for the critical point of strongly interacting matter. Currently NA61/SHINE uses the old NA49 software framework for reconstruction, simulation and data analysis. The core of this legacy framework was developed in the early 1990s. It is written in different programming and scripting languages (C, pgi-Fortran, shell) and provides several concurrent data formats for the event data model, which includes also obsolete parts. In this contribution we will introduce the new software framework, called Shine, that is written in C++ and designed to comprise three principal parts: a collection of processing modules which can be assembled and sequenced by the user via XML files, an event data model which contains all simulation and reconstruction information based on STL and ROOT streaming, and a detector description which provides data on the configuration and state of the experiment. To assure a quick migration to the Shine framework, wrappers were introduced that allow to run legacy code parts as modules in the new framework and we will present first results on the cross validation of the two frameworks.

Sipos, Roland; Laszlo, Andras; Marcinek, Antoni; Paul, Tom; Szuba, Marek; Unger, Michael; Veberic, Darko; Wyszynski, Oskar

2012-12-01

367

Absence of Na+/sugar cotransport activity in Barrett's metaplasia  

PubMed Central

AIM: To evaluate the presence of Na+-dependent, active, sugar transport in Barrett's epithelia as an intestinal biomarker, based on the well-documented, morphological intestinal phenotype of Barrett's esophagus (BE). METHODS: We examined uptake of the nonmeta-bolizable glucose analogue, alpha-methyl-D-glucoside (AMG), a substrate for the entire sodium glucose cotransporter (SGLT) family of transport proteins. During upper endoscopy, patients with BE or with uncomplicated gastroesophageal reflux disease (GERD) allowed for duodenal, gastric fundic, and esophageal mucosal biopsies to be taken. Biopsies were incubated in bicarbonate-buffered saline (KRB) containing 0.1 mmol/L 14C-AMG for 60 min at 20°C. Characterized by abundant SGLT, duodenum served as a positive control while gastric fundus and normal esophagus, known to lack SGLT, served as negative controls. RESULTS: Duodenal biopsies accumulated 249.84 ± 35.49 (SEM) picomoles AMG/?g DNA (n = 12), gastric fundus biopsies 36.20 ± 6.62 (n = 12), normal esophagus 12.10 ± 0.59 (n = 3) and Barrett’s metaplasia 29.79 ± 5.77 (n = 8). There was a statistical difference (P < 0.01) between biopsies from duodenum and each other biopsy site but there was no statistically significant difference between normal esophagus and BE biopsies. 0.5 mmol/L phlorizin (PZ) inhibited AMG uptake into duodenal mucosa by over 89%, but had no significant effect on AMG uptake into gastric fundus, normal esophagus, or Barrett’s tissue. In the absence of Na+ (all Na+ salts replaced by Li+ salts), AMG uptake in duodenum was decreased by over 90%, while uptake into gastric, esophageal or Barrett’s tissue was statistically unaffected. CONCLUSION: Despite the intestinal enterocyte phenotype of BE, Na+-dependent, sugar transport activity is not present in these cells.

Murray, Lisa J; Tully, Owen; Rudolph, David S; Whitby, Marysue; Valenzano, Mary C; Mercogliano, Giancarlo; Thornton, James J; Mullin, James M

2008-01-01

368

In search of synaptosomal Na + , K + ATPase regulators  

Microsoft Academic Search

The arrival of the nerve impulse to the nerve endings leads to a series of events involving the entry of sodium and the exit\\u000a of potassium. Restoration of ionic equilibria of sodium and potassium through the membrane is carried out by the sodium\\/potassium\\u000a pump, that is the enzyme Na+,K+-ATPase. This is a particle-bound enzyme that concentrates in the nerve ending

Georgina Rodríguez de Lores Arnaiz

1992-01-01

369

An analysis of Na + currents in rat olfactory receptor neurons  

Microsoft Academic Search

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

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

1992-01-01

370

Redetermination of durangite, NaAl(AsO4)F  

PubMed Central

The crystal structure of durangite, ideally NaAl(AsO4)F (chemical name sodium aluminium arsenate fluoride), has been determined previously [Kokkoros (1938). Z. Kristallogr. 99, 38–49] using Weissenberg film data without reporting displacement parameters of atoms or a reliability factor. This study reports the redetermination of the structure of durangite using single-crystal X-ray diffraction data from a natural sample with composition (Na0.95Li0.05)(Al0.91Fe3+ 0.07Mn3+ 0.02)(AsO4)(F0.73(OH)0.27) from the type locality, the Barranca mine, Coneto de Comonfort, Durango, Mexico. Durangite is isostructural with minerals of the titanite group in the space group C2/c. Its structure is characterized by kinked chains of corner-sharing AlO4F2 octa­hedra parallel to the c axis. These chains are cross-linked by isolated AsO4 tetra­hedra, forming a three-dimensional framework. The Na+ cation (site symmetry 2) occupies the inter­stitial sites and is coordinated by one F? and six O2? anions. The AlO4F2 octa­hedron has symmetry -1; it is flattened, with the Al—F bond length [1.8457?(4)?Å] shorter than the Al—O bond lengths [1.8913?(8) and 1.9002?(9)?Å]. Examination of the Raman spectra for arsenate minerals in the titanite group reveals that the position of the band originating from the As—O symmetric stretching vibrations shifts to lower wavenumbers from durangite, maxwellite [ideally NaFe(AsO4)F], to tilasite [CaMg(AsO4)F].

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

2012-01-01

371

Protire?ivý vplyv WikiLeaks na diplomaciu  

Microsoft Academic Search

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

Laura Meri?ková

2012-01-01

372

Na + :HCO 3 ? Cotransporters (NBC): Cloning and Characterization  

Microsoft Academic Search

.   The sodium bicarbonate cotransporter (NBC1) is essential for bicarbonate transport across plasma membranes in epithelial\\u000a and nonepithelial cells. The direction of the NaHCO3 movement in secretory epithelia is opposite to that in reabsorptive epithelia. In secretory epithelia (such as pancreatic\\u000a duct cells) NBC is responsible for the transport of bicarbonate from blood to the cell for eventual secretion at

M. Soleimani; C. E. Burnham

2001-01-01

373

Molecular dynamics studies of molten NaI  

Microsoft Academic Search

Molecular dynamics simulations of molten NaI have been performed using rigid-ion and polarizable-ion models. The trajectories of the ions have been analysed to give the mass, charge and number currents. The frequency spectra of the current autocorrelation functions have been determined. The inelastic neutron scattering spectrum is reported. The following major features are noted.Ionic polarization leads to a substantial change

M. Dixon

1983-01-01

374

Acrylamide Mitigation in Potato Chips by Using NaCl  

Microsoft Academic Search

In April 2002, Swedish researchers shocked the world when they presented preliminary findings on the presence of acrylamide\\u000a in fried and baked foods, most notably potato chips and French fries, at levels of 30–2,300 ppb. The objective of this research\\u000a was to study the effect of immersing potato slices in a NaCl solution over the acrylamide formation in the resultant potato

Franco Pedreschi; Kit Granby; Jørgen Risum

2010-01-01

375

NorM of Vibrio parahaemolyticus Is an Na+-Driven Multidrug Efflux Pump  

PubMed Central

NorM of Vibrio parahaemolyticus apparently is a new type of multidrug efflux protein, with no significant sequence similarity to any known transport proteins. Based on the following experimental results, we conclude that NorM is an Na+-driven Na+/drug antiporter. (i) Energy-dependent ethidium efflux from cells possessing NorM was observed in the presence of Na+ but not of K+. (ii) An artificially imposed, inwardly directed Na+ gradient elicited ethidium efflux from cells. (iii) The addition of ethidium to cells loaded with Na+ elicited Na+ efflux. Thus, NorM is an Na+/drug antiporting multidrug efflux pump, the first to be found in the biological world. Judging from the similarity of the NorM sequence to those of putative proteins in sequence databases, it seems that Na+/drug antiporters are present not only in V. parahaemolyticus but also in a wide range of other organisms.

Morita, Yuji; Kataoka, Atsuko; Shiota, Sumiko; Mizushima, Tohru; Tsuchiya, Tomofusa

2000-01-01

376

Uptake and reaction of HOBr on frozen and dry NaCl/NaBr surfaces between 253 and 233 K  

NASA Astrophysics Data System (ADS)

The uptake and reaction of HOBr with frozen salt surfaces of variable NaCl / NaBr composition and temperature were investigated with a coated wall flow tube reactor coupled to a mass spectrometer for gas-phase analysis. HOBr is efficiently taken up onto the frozen surfaces at temperatures between 253 and 233 K where it reacts to form the di-halogens BrCl and Br2, which are subsequently released into the gas-phase. The uptake coefficient for HOBr reacting with a frozen, mixed salt surface of similar composition to sea-spray was 10-2. The relative concentration of BrCl and Br2 released to the gas-phase was found to be strongly dependent on the ratio of Cl- to Br - in the solution prior to freezing / drying. For a mixed salt surface of similar composition to sea-spray the major product at low conversion of surface reactants (i.e. Br - and Cl-) was Br2. Variation of the pH of the NaCl / NaBr solution used to prepare the frozen surfaces was found to have no significant influence on the results. The observations are explained in terms of initial formation of BrCl in a surface reaction of HOBr with Cl-, and conversion of BrCl to Br2 via reaction of surface Br -. Experiments on the uptake and reaction of BrCl with frozen NaCl / NaBr solutions served to confirm this hypothesis. The kinetics and products of the interactions of BrCl, Br2 and Cl2 with frozen salt surfaces were also investigated, and lower limits to the uptake coefficients of > 0.034, >0.025 and >0.028 respectively, were obtained. The uptake and reaction of HOBr on dry salt surfaces was also investigated and the results closely resemble those obtained for frozen surfaces. During the course of this study the gas diffusion coefficients of HOBr in He and H2O were also measured as (273 ± 1) Torr cm2 s-1 and (51 ± 1) Torr cm2 s-1, respectively, at 255 K. The implications of these results for modelling the chemistry of the Arctic boundary layer in springtime are discussed.

Adams, J. W.; Holmes, N. S.; Crowley, J. N.

2002-04-01

377

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

NASA Astrophysics Data System (ADS)

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

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

1999-09-01

378

Magnetic properties of Fe clusters in NaY zeolite  

NASA Astrophysics Data System (ADS)

Clusters of up to 28 Fe(0) atoms have been introduced into the 'supercages' of NaY zeolite by iron exchange of Fe(2+) for Na(+) followed by reduction to Fe(0) with solvated electrons and Na(-1) ions. The temperature-dependent ac and dc susceptibilities, which exhibit Curie-Weiss behavior before reduction, change to something approximating superparamagnetic behavior afterwards. The blocking temperature, T(sub b) shows a strong dependence on magnetic field but weak dependence on frequency. There is a best a very weak remanence and coercive field while the onset of irreversibility occurs at temperatures well above T(sub b). In addition, the real and imaginary parts of the ac susceptibility show essentially similar temperature dependence. Some of this anomalous behavior can be attributed to a distribution of particle sizes. To the best of our knowledge these preliminary data-while poorly understood-represent the first measurements fo the temperature, frequency, and field dependence of the magnetic properties of such small clusters.

Cowen, J. A.; Tsai, K. L.; Dye, J. L.

1994-11-01

379

The local distribution of NA I interstellar gas  

NASA Astrophysics Data System (ADS)

We present high-resolution absorption measurements (lambda/Delta lambda approximately 75,000) of the interstellar Na I D lines at 5890 A toward 80 southern hemisphere early-type stars located in the local interstellar medium (LISM). Combining these results with other sodium measurements taken from the literature, we produce galactic maps of the distribution of neutral sodium column density for a total of 293 stars generally lying within approximately 250 pc of the Sun. These maps reveal the approximate shape of the mid-plane contours of the rarefied region of interstellar space termed the Local Bubble. Its shape is seen as highly asymmetric, with a radius ranging from 30 to 300 pc, and with an average radius of 60 pc. Similar plots of the Galactic mid-plane distribution of sources emitting extreme ultraviolet radiation show that they also trace out similar contours of the Local Bubble derived from Na I absorption measurements. We conclude that the Local Bubble absorption interface can be represented by a hydrogen column density, NuETA = 2 x 1019 cm-2, which explains both the local distribution of Na I absorption and the observed galactic distribution of extreme ultraviolet sources. The derived mid-plane contours of the Bubble generally reproduce the large-scale features carved out in the interstellar medium by several nearby galactic shell structures.

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

1994-12-01

380

Optimization of BARC process for hyper-NA immersion lithography  

NASA Astrophysics Data System (ADS)

The extension of current 193nm immersion lithography technology is depending on increasing the numerical aperture (NA). High-resolution imaging requires the decrease of photoresist thickness to compensate for smaller depth of focus (DOF) and prevent pattern collapse. Poor etch selectivity between photoresist and BARC reads to the use of thinner BARC with faster etch-rate. Also, controlling reflectance over a wider range of incident angles for hyper-NA above 1.0 gives more challenge for thin BARC. To reduce substrate reflectivity, various material strategies (dual-layer BARC such as organic/inorganic BARC or organic/organic BARC, Si-based ARC/spin-on carbon (SOC), and so on) have been introduced through many papers. Organic dual-layer BARC is capable of suppressing reflectivity through wide range of incident angles. But, the inevitable increase of its thickness is not a desirable direction due to the decreasing trend of photoresist thickness. When amorphous carbon (a-C) is used as a hardmask for sub-stack, the combination of organic/inorganic BARC (i.e. SiON) is currently well known process. Si-ARC/SOC may be the promising candidates of hardmask because Si component of Si-ARC affords a high etch selectivity to photoresist and its combination with SOC decreases reflectance. The optical constants of above organic materials can be tuned to control the substrate reflectivity for hyper-NA.

Lee, Kilyoung; Lee, Junghyung; Lee, Sungkoo; Park, Dongheok; Bok, Cheolkyu; Moon, Seungchan

2008-04-01

381

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

382

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

383

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

384

New results on kaon decays from NA48  

NASA Astrophysics Data System (ADS)

We report on recent results on rare and semileptonic kaon decays from NA48 and NA48/2. Using data from a minimum bias run in 1999 we present a new measurement of the CP violating decay K??? with over 40000 selected events. We measured the ratio ?(K???)/?(K??e?)=(4.835±0.038)×10 leading to the precise determination of the CP violation parameter |?-|=(2.223±0.013)×10. From the same data we selected over 2×10K???? decays. Preliminary results from a dalitz plot fit yield the values for the form factors ?=0.0260±0.0007±0.0010 and ?=0.0120±0.0008±0.0015. In one month of data taking in 2003 the NA48/2 experiment collected over 2×10K???? decays. A measurement of the relative contributions of Inner Bremsstrahlung, Direct Emission, and their interference is presented which results in frac(DE)=(3.35±0.35±0.25)% and frac(INT)=(-2.67±0.81±0.73)% showing for the first time a non-zero value of the interference term.

Gersabeck, M.

2007-12-01

385

Red Blood Cell Na pump: Insights from Species Differences  

PubMed Central

The red blood cell membrane is specialized to exchange chloride and bicarbonate; usually the pH gradient, the chloride ratio, and the membrane potential are tightly coupled. We review the evidence that led to the ability to separately vary inside and outside pH in red cells. The effect of pH on Na pump activity and on the selectivity of the inside and the outside transport sites is reviewed. In red blood cells, at high pH, the outside site is not selective. An increase in protons leads to an increase in K+ affinity, thus making the site more selective. The pK for this site is different in rats and humans; because of the high conservation of residues in these two species, there are only a few possible residues that can account for this difference. On the inside, work from unsided preparations suggests that, at high pH, the transport site is highly selective for Na+. Once again, an increase in protons leads to an increase in K+ affinity, but now the result is a less selective site. During their maturation, reticulocytes lose many membrane proteins. The type and fractional loss is species dependent. For example, most reticulocytes lose most of their Na pumps, retaining about 100 pumps per cell, but animals from the order Carnivora lose all their pumps. We review some of the evidence that PKC phosphorylation of N-terminus serines is responsible for endocytosis in other cell types and species variation in this region.

Gatto, Craig

2009-01-01

386

Hydrogenation properties of KSi and NaSi Zintl phases.  

PubMed

The recently reported KSi-KSiH(3) system can store 4.3 wt% of hydrogen reversibly with slow kinetics of several hours for complete absorption at 373 K and complete desorption at 473 K. From the kinetics measured at different temperatures, the Arrhenius plots give activation energies (E(a)) of 56.0 ± 5.7 kJ mol(-1) and 121 ± 17 kJ mol(-1) for the absorption and desorption processes, respectively. Ball-milling with 10 wt% of carbon strongly improves the kinetics of the system, i.e. specifically the initial rate of absorption becomes about one order of magnitude faster than that of pristine KSi. However, this fast absorption causes a disproportionation into KH and K(8)Si(46), instead of forming the KSiH(3) hydride from a slow absorption. This disproportionation, due to the formation of stable KH, leads to a total loss of reversibility. In a similar situation, when the pristine Zintl NaSi phase absorbs hydrogen, it likewise disproportionates into NaH and Na(8)Si(46), indicating a very poorly reversible reaction. PMID:22930067

Tang, Wan Si; Chotard, Jean-Noël; Raybaud, Pascal; Janot, Raphaël

2012-10-14

387

CP Violation Results from the NA48 experiments  

NASA Astrophysics Data System (ADS)

The main goal of the NA48 experiments at the CERN SPS has been the search for direct CP violation (CPV) in kaon decays. In this article two selected results will be presented. In the neutral kaon sector, NA48 determined ?+-, related to the parameters of indirect and direct CPV (?+- = ?+?'), from data collected during a dedicated run in 1999 with a pure KL beam. Using a sample of 47000 KL-->?+?- and 5 million KL-->?+/-e-/+?, we extract |?+-| = (2.223+/-0.012)×10-3. In the charged kaon decays, NA48/2 has measured the asymmetry Ag = (g+-g-)/(g++g-). of the linear slope parameter g in the Dalitz plot of K+/--->3? decays from data collected in 2003 and 2004. Any non-zero value of Ag would be evidence for direct CPV. A new technique of asymmetry measurement, involving simultaneous K+ and K- beam and a large data sample allowed a result of unprecedented precision. The charge asymmetry parameter was measured to be Agc = (-1.5+/-2.1)×10-4 with 3.11×109 K+/--->?+/-?+?- decays, and Agn = (1.8+/-1.8)×10-4 with 9.13×107 K+/--->?+/-?0?0 decays. The results are compatible with the SM predictions, i.e. no evidence for direct CP violation at the order of 10-4 has been found.

Anzivino, Giuseppina

2007-11-01

388

Factors dominating adhesion of NaCl onto potato chips.  

PubMed

In this study, the adhesion factors examined were time between frying and coating, surface oil content, chip temperature, oil composition, NaCl size, NaCl shape, and electrostatic coating. Three different surface oil content potato chips, high, low, and no, were produced. Oils used were soybean, olive, corn, peanut, and coconut. After frying, chips were coated immediately, after 1 d, and after 1 mo. NaCl crystals of 5 different particle sizes (24.7, 123, 259, 291, and 388 microm) were coated both electrostatically and nonelectrostatically. Adhesion of cubic, dendritic, and flake crystals was examined. Chips were coated at different temperatures. Chips with high surface oil had the highest adhesion of salt, making surface oil content the most important factor. Decreasing chip temperature decreased surface oil and adhesion. Increasing time between frying and coating reduced adhesion for low surface oil chips, but did not affect high and no surface oil chips. Changing oil composition did not affect adhesion. Increasing salt size decreased adhesion. Salt size had a greater effect on chips with lower surface oil content. When there were significant differences, cubic crystals gave the best adhesion followed by flake crystals then dendritic crystals. For high and low surface oil chips, electrostatic coating did not change adhesion of small size crystals but decreased adhesion of large salts. For no surface oil content chips, electrostatic coating improved adhesion for small salt sizes but did not affect adhesion of large crystals. PMID:17995602

Buck, V E; Barringer, S A

2007-10-01

389

Structure of the intercalate NaWO2Cl2  

NASA Astrophysics Data System (ADS)

NaWO2Cl2, Fw = 309.74, is formed by the intercalation of sodium into WO2Cl2. The structure of the intercalate has been determined using a combination of constant wavelength and time-of flight powder neutron diffraction data. NaWO2Cl2 adopts orthorhombic symmetry, space group Ammm (No. 65), with a = 3.7943(3), b = 3.8006(4), and c = 15.739(1) Å Z = 2; V = 226.96 Å3 and Dcal = 4.53 g cm-3. The structure consists of blocks, each containing a layer of both W and O atoms sandwiched between two layers of Cl atoms. The trilayer blocks [Cl-WO2-Cl] are stacked in the direction perpendicular to the layers, i.e., parallel to the c-axis, and are separated by Na+ ions located in two sets of sites between adjacent chlorine layers. The basic structure is related to that of the parent material WO2Cl2 by a displacement of the [Cl-WO2-Cl] blocks in the basal plane.

Abrahams, I.; Nowinski, J. L.; Bruce, P. G.; Gibson, V. C.

1991-10-01

390

(Na) sub i modulates isoproterenol's effect on Ca permeability in cultured heart cells  

Microsoft Academic Search

Isoproterenol (ISO) augments the slow inward Ca current in cardiac muscle cells. The authors examined the role of intracellular Na (Na{sub i}) on ISO-mediated alterations in Ca uptake in cultured chick heart cells. In 140 mM Na medium, 1 μM ISO did not measurably alter ⁴⁵Ca uptake. When cells were first preincubated in Na-free medium for 5 min and then

D. Kim; T. W. Smith

1987-01-01

391

NaCl-stimulated proton efflux and cell expansion in sugar-beet leaf discs  

Microsoft Academic Search

The expansion of illuminated sugar-beet leaf discs floating on aqueous solutions is stimulated by 10 mM NaCl. During expansion, protons are pumped out of the cell and NaCl increases this proton flux by about 40%. The nett flux of K+ and Na+ into the discs was also evaluated. During the expansion period K+ decreases while Na+ increases markedly. The results

M. A. Nunes; M. M. Correia; M. D. Lucas

1983-01-01

392

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

393

Phospholemman-Phosphorylation Mediates the Adrenergic Effects on Na\\/K Pump Function in Cardiac Myocytes  

Microsoft Academic Search

Cardiac sympathetic stimulation activates -adrenergic (-AR) receptors and protein kinase A (PKA) phosphorylation of proteins involved in myocyte Ca regulation. The Na\\/K-ATPase (NKA) is essential in regulating intracellular (Na) ((Na)i), which in turn affects (Ca)i via Na\\/Ca exchange. However, how PKA modifies NKA function is unknown. Phospholemman (PLM), a member of the FXYD family of proteins that interact with NKA

Sanda Despa; Julie Bossuyt; Fei Han; Kenneth S. Ginsburg; Li-Guo Jia; Howard Kutchai; Amy L. Tucker; Donald M. Bers

2010-01-01

394

PLUGGING LEAKS BETWEEN WATER AND THIRD FLUID SYSTEM (NaK). Memo Report 117  

Microsoft Academic Search

An investigation was made to find a NaK additive which could be used to ; seal NaK-water leaks in systems such as the S2C evaporator and superheater. A ; mixture of 1 wt. % FeâOâ and 0.2 wt. % asbestos plugged a leak of ; 0.3 liter NaK\\/hr, but only partially plugged a 1.0 liter NaK\\/hr leak. The leak ;

S. J. Rodgers; J. W. Mausteller

1956-01-01

395

beta-delayed gamma spectroscopy of neutron rich Na27,28,29  

Microsoft Academic Search

The low-energy level structure of the exotic Na isotopes Na27,28,29 has been investigated through beta-delayed gamma spectroscopy. Detailed level structure of Na28,29 has been obtained through betagamma and betagammagamma coincidence measurements. The low-lying levels populated in Na27 by beta decay were found to corroborate well with the in-beam data from the literature. Half-lives of the parent nuclides, Ne27,28,29, were measured

Vandana Tripathi; S. L. Tabor; C. R. Hoffman; M. Wiedeking; A. Volya; P. F. Mantica; A. D. Davies; S. N. Liddick; W. F. Mueller; A. Stolz; B. E. Tomlin; T. Otsuka; Y. Utsuno

2006-01-01

396

Cation transport systems in mitochondria: Na + and K + uniports and exchangers  

Microsoft Academic Search

It is now well established that mitochondria contain three antiporters that transport monovalent cations. A latent, allosterically regulated K+\\/H+ antiport appears to serve as a cation-extruding device that helps maintain mitochondrial volume homeostasis. An apparently unregulated Na+\\/H+ antiport keeps matrix [Na+] low and the Na+-gradient equal to the H+-gradient. A Na+\\/Ca2+ antiport provides a Ca2+-extruding mechanism that permits the mitochondrion

Gerald P. Brierley; Kemal Baysal; Dennis W. Jung

1994-01-01

397

Na sup + -K sup + -ATPase-dependent sodium flux in cortical collecting tubule  

SciTech Connect

The instantaneous rate of efflux of intracellular Na was studied in rabbit isolated cortical collecting tubules (CCT) as a function of temperature and intracellular Na concentration ((Na){sub i}). (Na){sub i} of microdissected CCT was increased by cold and K-free exposure in the presence of {sup 22}Na and the extracellular tracer ({sup 3}H)sorbitol. (Na){sub i} rose rapidly to 40 mM at 30 min, after which it rose more slowly, reaching 120-140 mM at 6 h. Kinetics of Na efflux were studied after rapid rewarming, using a special device allowing measurements at 20-s intervals. Under control conditions, the total Na load was extruded in <8 min, whereas, in the presence of 10{sup {minus}4} M ouabain, only 50% of the load was extruded during this period of time. Ouabain-sensitive Na efflux was first evident at 13{degree}C and gradually increased between 13 and 35{degree}C. At 37{degree}C, Na{sup +}-K{sup +}-ATPase-dependent Na efflux was dependent on (Na){sub i}. This efflux gradually increased, from 0.05 to 0.5 peq{center dot}nl tubular volume{sup {minus}1}{center dot}s{sup {minus}1} as a function of (Na){sub i} and reached a plateau at 70 mM (Na){sub i}. It is concluded that (Na){sub i} is a major modulator of the pump activity in CCT; at normal levels of (Na){sub i}, the pump is operating at only a small fraction of its total capacity.

Blot-Chabaud, M.; Jaisser, F.; Gingold, M.; Bonvalet, J.P.; Farman, N. (CEntre d'Etudes Nucleaires de Saclay, Gif sur Yvette (France))

1988-10-01

398

Synthesis and spectroscopic characterization of P-doped Na 4Si 4  

Microsoft Academic Search

Na4Si4 is a Zintl salt composed of Na+ cations and Si44? tetrahedral anions and is a unique solid-state precursor to clathrate structures and nanomaterials. In order to provide opportunities for the synthesis of complex materials, phosphorus was explored as a possible substituent for silicon. Phosphorus doped sodium silicides Na4Si4?xPx (x?0.04) were prepared by reaction of Na with the mechanically alloyed

Jialing Wang; Sabyasachi Sen; Ping Yu; Nigel D. Browning; Susan M. Kauzlarich

2010-01-01

399

Modelling Dysregulated Na1 Absorption in Airway Epithelial Cells with Mucosal Nystatin Treatment  

Microsoft Academic Search

In cystic fibrosis (CF), the absence of functional CFTR leads to dysregulated Na1 absorption across airway epithelia. We estab- lished an in vitro model of dysregulated Na1 absorption by treating polarized normal human bronchial epithelial cells (HBEs) with nystatin(Nys),apolyeneantibioticthatenablesmonovalentcations to permeate biological membranes. Acute mucosal Nys produced a rapid increase in short circuit current (Isc) that reflected increased transepithelialNa1absorptionandrequiredNa1\\/K1ATPaseactivity. TheacuteincreaseinIscwasassociatedwithincreasedmucosalliquid

Alessandra Livraghi; Marcus Mall; Anthony M. Paradiso; Richard C. Boucher; Carla M. Pedrosa Ribeiro

400

Absolute neutron cross sections for the production of the 24Na isomer from magnesium and aluminium  

Microsoft Academic Search

The cross sections for the 24Mg(n,p)24mNa and 27Al (n, alpha)24mNa reactions were measured using the cyclic activation technique and a high-energy resolution Ge(Li) detector. The experimentally determined values of production cross sections are sigma[24Mg(n, p)24mNa] = 138+\\/-14 mbn and sigma[27Al(n, alpha)24mNa] = 65+\\/-6 mb.

G. N. Salaita

1971-01-01

401

NMR analysis of cellulose dissolved in aqueous NaOH solutions  

Microsoft Academic Search

Low molecular weight cellulose (degree of polymerization = ca 15) was dissolved in 4-- 30% NaOD\\/D2O, and relationships between 1H- and 13C-chemical shifts of the cellulose and NaOD concentrations were studied in terms of the dissociation of three hydroxyl groups of cellulose in aqueous NaOH solutions. All C---H proton resonances were shifted upfield linearly with an increase in the NaOD

AKIRA Isogai

1997-01-01

402

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

Microsoft Academic Search

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

H. Koepsell; J. Spangenberg

1994-01-01

403

A Na/beta double prime-alumina/NaAlCl4, Cl2/C circulating cell  

NASA Astrophysics Data System (ADS)

A Na/beta double prime-alumina/NaAlCl4, Cl2/C circulating cell at 200 C has been successfully demonstrated. A circulating system was operated for over two weeks to charge and discharge this cell. This cell can sustain continuous discharge at 9 mA/sq cm and an output cell voltage greater than 3.2 V for 42 hours. Linear sweep voltametry was used to characterize the cell at different charging and discharging states. The results of experiment and modeling show a typical I-R drop across the cell and the possibility of improving the discharge performance of the cell to over 150 mA/sq cm at 3.2 V.

Cherng, J. Y.; Bennion, D. N.

404

Evidence of sympathetic cooling of Na+ ions by a Na magneto-optical trap in a hybrid trap  

NASA Astrophysics Data System (ADS)

A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutral atoms. This system provides a general cooling method that can be applied to species that do not have optically accessible transitions and can also potentially cool internal degrees of freedom. The long-range polarization potentials (V?-?/r4) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling of trapped Na+ ions, which are closed shell and therefore do not have a laser-induced atomic transition from the ground state, by equal-mass cold Na atoms in a magneto-optical trap.

Sivarajah, I.; Goodman, D. S.; Wells, J. E.; Narducci, F. A.; Smith, W. W.

2012-12-01

405

[Na + ] i \\/[K + ] i -independent death of ouabain-treated renal epithelial cells is not mediated by Na + ,K + ATPase internalization and de novo gene expression  

Microsoft Academic Search

The cytotoxic effect of long-term exposure of renal epithelial cells to ouabain and other cardiotonic steroids (CTS) is mediated\\u000a by the interaction of these compounds with Na+,K+-ATPase but is independent of the inhibition of Na+,K+-ATPase-mediated ion fluxes. Sustained application of CTS also leads to Na+,K+-ATPase endocytosis and its translocation into the nuclei that might trigger the cell death machinery via

Olga A. Akimova; Pavel Hamet; Sergei N. Orlov

2008-01-01

406

NaCl effect on the excited-state proton dissociation reaction of naphthols: water structure in the presence of NaCl  

Microsoft Academic Search

The NaCl effect on the proton dissociation reaction in water at 300 K has been studied by means of nanosecond and picosecond spectroscopy with fluorimetry. The proton dissociation rate constant k⁠decreased with an increase of NaCl according to the equation k⁠= kâ((HâO)â)(1 - ..cap alpha..(NaCl)), where kâ denotes the second-order rate constant for the proton transfer from excited

H. Shizuka; T. Ogiwara; A. Narita; M. Sumitani; K. Yoshihara

1986-01-01

407

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

Microsoft Academic Search

Evidence for competition between Li+ and Na+ for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li+ upon the 23Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na+-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed

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

1999-01-01

408

NaCl interaction with interfacially polymerized polyamide films of reverse osmosis membranes: A solid-state 23Na NMR study  

Microsoft Academic Search

23Na nuclear magnetic resonance (NMR) spectroscopy of NaCl-exchanged polyamide (PA) films comparable to those of the active skin layer of many reverse osmosis (RO) membranes provides novel insight into the structural environments and dynamical behavior of Na+ in such films. Unsupported PA films were synthesized via interfacial polymerization of trimesoyl chloride in hexane and m-phenylenediamine in aqueous solution, and SEM,

Xiang Xu; R. James Kirkpatrick

2006-01-01

409

The transfer of titanium and boron to aluminium master alloys via Na 2 TiF 6 and NaBF 4  

Microsoft Academic Search

Na2TiF6 and NaBF4 are studied as alternatives to their potassium equivalents for use in aluminium master alloy manufacture and the transfer efficiencies of B and Ti in various systems reported. The compositions of the slags formed in the reactions are used, along with the phase diagrams for the KF-AlF3 and NaF-AlF3 systems, to discuss the nature of the reactions between

J. D. Donaldson; C. P. Squire; F. E. Stokes

1978-01-01

410

Regulation by endothelin-1 of Na +Ca 2+ exchange current (I NaCa) from guinea-pig isolated ventricular myocytes  

Microsoft Academic Search

Summary The cardiac Na+-Ca2+ exchanger participates in Ca homeostasis, and Na+-Ca2+ exchanger-mediated ionic current (INaCa) also contributes to the regulation of cardiac action potential duration. Moreover, INaCa can contribute to arrhythmogenesis under conditions of cellular Ca overload. Although it has been shown that the peptide hormone endothelin-1 (ET-1) can phosphorylate the cardiac Na+-Ca2+ exchanger via protein kinase C (PKC), little

Y. H. Zhang; A. F. James; J. C. Hancox

2001-01-01

411

Response of the 23Na-NMR double-quantum filtered signal to changes in Na+ ion concentration in model biological solutions and human erythrocytes.  

PubMed

Double quantum filtered (DQF) 23Na-NMR signals were evaluated as a function of [Na+] at constant temperature in two model systems (bovine serum albumin (BSA) and Ficoll 400) and in human red blood cells (RBCs). In model systems, the ratio of double quantum filtered to single quantum (SQ) signal intensities was independent of [Na+], even over a wide range of Na+/K+ ratios. Varying the DQF preparation time affected only the DQF signal intensity. In contrast, in human red blood cells (RBCs) the shape and phase of the DQF intracellular Na+ signal (Na+in) varied as a function of preparation time. Similar observations in cartilage [Eliav, U., Shinar, H. and Navon, G. (1992) J. Magn. Reson. 28, 223-229] have been attributed to the generation of a second- and a third-rank tensor by the DQF pulse sequence, resulting from Na+ ion ordering. By using a DQF sequence which isolates the second-rank tensor only, this component was found to originate from the intracellular Na+ ion pool in human RBCs, as well as from interactions of Na+ ions with the extracellular face of the plasma membrane. The residual quadrupolar splitting for the signal originating from the former environment was shown to be less than the SQ linewidth, explaining its absence in SQ spectra, and this was confirmed by two-dimensional DQF 23Na-NMR experiments. By isolating the contribution from the third-rank tensor exclusively, the ratio of DQF:SQ signal intensities for Na+in in human RBCs was shown to be constant over a 4-fold change in [Na+in] produced by addition of an ionophore (nystatin). This indicates that such changes in physiological state do not alter the efficiency of DQF signal generation in human RBCs. PMID:8399316

Tauskela, J S; Shoubridge, E A

1993-10-01

412

Abnormalities of Na/K ATPase in migraine with aura.  

PubMed

It has been previously shown from our laboratory that abnormal functioning of Na/K ATPase can cause spreading depression, the likely mechanism of migraine aura. We used lymphocytes to investigate whether or not membrane Na/K ATPase is altered in migraine with aura patients. Lymphocytes were prepared from such patients, aged 20-45 years, and from age-matched healthy volunteers (controls). The binding of 3H- ouabain was studied using increasing concentrations (0.5-25 nm) of this radioligand, specific for Na/K-ATPase. We studied 19 migraine with aura patients and 22 healthy volunteers, matched for age and sex. B(max) (fmol/mg protein) and K(D) (nM) were not different between patients and controls. However, their ratio (B(max)/K(D)) was higher in patients than in controls. B(max) was (mean +/- SD) 270 +/- 110 fmol/mg protein in controls, and 360 +/- 230 in migraine with aura patients (P = 0.10, t-test). K(D) was (mean +/- SD) 2.8 +/- 1.5 nm in controls, and 2.9 +/- 3.2 nm in migraine with aura patients (P = 0.88, t-test). B(max)/K(D) was (mean +/- SD) 120 +/- 78 in controls, and 210 +/- 190 in migraine patients (P = 0.046, t-test). Moreover, no control patient had a B(max)/K(D) ratio greater than 398, while three migraine patients had ratios of 417, 572 and 722, respectively. Ouabain binding is affected by Na/K ATPase structure (K(D)) and expression (B(max)). While these parameters were not altered in migraine with aura patients, the difference in their ratio suggests an imbalance between the enzyme's ouabain affinity and its expression, with higher-affinity subtypes being more expressed than normal. Moreover, single patients had values quite different from the control population. Our data suggest that (i) ouabain binding to lymphocyte membranes may be a useful tool in the diagnosis of migraine with aura and (ii) Na/K ATPase abnormalities may be involved in migraine aura. PMID:17257232

Scarrone, S; Podestà, M; Cupello, A; Finocchi, C; Frassoni, F; Gandolfo, C; Balestrino, M

2007-02-01

413

Na/beta-Alumina/NAALCL4, CL2/C Circulating Cell.  

National Technical Information Service (NTIS)

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 circ...

J. Cherng D. N. Bennion

1987-01-01

414

Determination of the driving force of the Na + pump in toad bladder by means of vasopressin  

Microsoft Academic Search

Summary Vasopressin stimulates Na+ transport across toad bladder largely or entirely by decreasing the resistance to Na+ entry into the transporting epithelial cells. Therefore, the hormone should induce proportional changes in short circuit current (IS) and tissue conductance; the ratio of these changes should equal the driving force (ENa) of the Na+ pump.

Jacob Yonath; Mortimer M. Civan

1971-01-01

415

Na+\\/H+Exchangers: Linking Osmotic Dysequilibrium to Modified Cell Function  

Microsoft Academic Search

The Na+\\/H+ exchangers (NHEs) are among the major ion transporters involved in cell volume regulation. NHE activation leads to a cellular influx of Na+ ions and extrusion of H+ ions, which are readily replenished from intracellular buffers. This will result in a net import of Na+. In many systems NHE operates in parallel to Cl–-\\/ HCO33– exchange, resulting in cellular

Markus Ritter; Johannes Fuerst; Ewald Wöll; Sabine Chwatal; Martin Gschwentner; Florian Lang; Peter Deetjen; Markus Paulmichl

2001-01-01

416

Distribution of (Na + +K + )ATPase and sodium channels in skeletal muscle and electroplax  

Microsoft Academic Search

Summary The distributions of (Na+ + K+)ATPase and sodium channels in skeletal muscle fibres and electrocytes were determined by immunofluorescent and immunoelectron microscopic techniques using antibodies against rat and eel (Na+ + K+)ATPase and the eel electric organ sodium channel. The extrajunctional sarcolemma of skeletal muscle was uniformly stained by polyclonal antibodies against (Na+ + K+)ATPase and the sodium channel.

R. G. Ariyasu; T. J. Deerinck; S. R. Levinson; M. H. Ellisman

1987-01-01

417

Thermodynamic Effects of Na on the Morphology of PbTe-PbS Nanostructured Thermoelectrics  

NASA Astrophysics Data System (ADS)

The creation of nanostructures via phase separation provides a mechanism for decreasing the lattice thermal conductivity and increasing the figure of merit of bulk thermoelectric materials like PbTe-PbS. The addition of Na to PbTe-PbS drastically alters the morphology of PbS precipitates in the system. To see if this change in morphology can be attributed to equilibrium thermodynamics, we use first-principles density functional theory (DFT) calculations to study the energetics of Na partitioning between PbTe and PbS and Na segregation at PbTe/PbS interfaces. We calculate a variety of Na defects in PbTe and PbS and find that the lowest energy defect in both PbTe and PbS is Na substituted for Pb. From the Na defect formation energies, we find the solubility limit of Na in PbTe and PbS, as well as the partitioning coefficient between PbTe and PbS. We find that Na partitions to PbS over PbTe, in agreement with experiment. We calculate Na segregation energies by substituting Na for Pb at the PbTe/PbS interface and find that Na segregates at the PbTe-side of the interface, in qualitative agreement with atom-probe tomography analysis. Applying the Gibbs adsorption isotherm to Na segregation, we find a corresponding decrease in interfacial energy leading to a change in morphology.

Doak, Jeff; He, Jiaqing; Blum, Ivan; Girard, Steven; Zhao, Li-Dong; Seidman, David; Kanatzidis, Mercouri; Dravid, Vinayak; Wolverton, Chris; Wang, Hui-Qiong; Zheng, Jin-Cheng; Casillas, Gilberto; Jose-Yacaman, Miguel

2013-03-01

418

Analytical models for the responses of the mesospheric OH* and Na layers to atmospheric gravity waves  

Microsoft Academic Search

Analytic models are developed to describe gravity wave induced perturbations in the high v OH* Meinel Band emissions and in atomic Na density. The results are used to predict the fluctuations in OH* intensity and rotational temperature, Na abundance, and the centroid heights of the OH* and Na layers. The OH* model depends critically on the assumed form for the

Gary R. Swenson; Chester S. Gardner

1998-01-01

419

Optical, phonon and structural analysis of Na doped ZnO nanostructures  

Microsoft Academic Search

We report optical properties and X- ray peak broadening analysis of the Na doped ZnO nanostructures. To prepare Na doped ZnO, simple room temperature wet chemical method is adopted. X ray diffraction pattern shows prepared particles are in hexagonal wurtzite structure. The individual contributions of small crystallite sizes and lattice strain to the peak broadening in undoped and Na doped

T. Pandiyarajan; B. Karthikeyan

2011-01-01

420

Relationship between L-glutamate-regulated intracellular Na + dynamics and ATP hydrolysis in astrocytes  

Microsoft Academic Search

Summary. Glutamate uptake into astrocytes and the resulting increase in intracellular Na + (Na + i) have been identified as a key signal coupling excitatory neuronal activity to increased glucose utilization. Arguments based mostly on mathematical modeling led to the conclusion that physiological concentrations of glutamate more than double astrocytic Na +\\/K +-ATPase activity, which should proportionally increase its ATP

P. J. Magistretti; J.-Y. Chatton

2005-01-01

421

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

PubMed

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

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

2012-10-12

422

Removal of Ca and Zn from aqueous solutions by zeolites NaP and KP  

Microsoft Academic Search

Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca) and zinc (Zn) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K with Na which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K on zeolite NaP was determined through

Alias Mohd Yusof; Nik Ahmad Nizam Nik Malek; Nurul Asyikin Kamaruzaman; Muhammad Adil

2010-01-01

423

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

National Technical Information Service (NTIS)

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 pr...

G. J. Sevigny M. S. Fountain S. Balagopal S. Bhavaraju

2009-01-01

424

Abertura Financeira e Vulnerabilidade Externa na América Latina: os impactos sobre Brasil, México e Argentina  

Microsoft Academic Search

Resumo: Este trabalho, na primeira seção, define o que costuma ser entendido como um processo de abertura financeira, identifica os níveis que compõem este processo, e lista as principais justificativas teóricas costumeiramente apresentadas para a implementação deste tipo de política. Na segunda seção, discute-se teoricamente o impacto dos processos de liberalização financeira na autonomia de política econômica e no grau

Juan Pablo Painceira; Marcelo Dias Carcanholo

425

Qualidade fisiológica de sementes de milho, feijão, soja e alface na presença de extrato de tiririca  

Microsoft Academic Search

RESUMO - A espécie Cyperus rotundus (tiririca) é perene e de difícil controle. Os órgãos subterrâneos dessa ciperácea produzem inibidores capazes de interferir na germinação e no crescimento de plântulas e de plantas de várias espécies, fenômeno chamado de alelopatia. A inibição na germinação de sementes pode estar associada à interferência de substâncias alelopáticas na atividade de enzimas chaves no

Fabiana Rezende Muniz; Maria das Graças Cardoso; Édila Vilela Resende Von Pinho; Michelle Vilela

2007-01-01

426

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

Microsoft Academic Search

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

B. Rajasekhar; John M. C. Plane

1993-01-01

427

Na + -dependent ionophore as part of the small polypeptide of the (Na + +K + )ATPase from eel electroplax membrane  

Microsoft Academic Search

Summary The (Na++K+)-ATPase from eel electroplax membranes is resolved into two polypeptides by means of sodium dodecyl sulfate (SDS) preparative gel electrophoresis. From the literature, the larger polypeptide has been known to have a molecular weight in the range of 85,000 to 135,000, while the molecular weight of the smaller polypeptide is known to be between 40,000 and 60,000. When

Adil E. Shamoo; Marjory Myers

1974-01-01

428

Electrochemical behavior of silicon compound in LiF–NaF–KF–Na 2 SiF 6 molten salt  

Microsoft Academic Search

The electrochemical reduction and nucleation process of Si4+ on an electrical steel electrode in the eutectic LiF–NaF–KF molten salt were investigated at 750 °C, by means of cyclic voltammetry\\u000a and chronoamperometry technique. Silicon was electrodeposited on steel, and Fe3Si was formed by the diffusivity of silicon on the electrode surface. The electrochemical reduction of Si4+ process in single-step charge transfer and

Zongying Cai; Yungang Li; Wei Tian

429

Electronic absorption spectra of nickel dichloride and nickel oxide solutions in the 2CsCl-NaCl and KCl-NaCl metls  

Microsoft Academic Search

The electronic absorption spectra of nickel dichloride and nickel oxide dilute solutions in the 2CsCl-NaCl and KCl-NaCl melts\\u000a have been measured by ultraviolet reflection absorption spectroscopy in the range 250–2500 nm. The spectroscopic data demonstrate\\u000a the formation of stable Ni(II)-based tetrahedral groups (NiCl\\u000a 4\\u000a 2?\\u000a ) in solutions of nickel dichloride in the 2CsCl-NaCl melt, whereas in the KCl-NaCl melt,

A. A. Khokhryakov; M. V. Mikhaleva; A. S. Paivin

2006-01-01

430

Lyman-. cap alpha. emission in collisions of H/sup +/ ions with Na(3s) and laser-excited Na(3p) atoms  

SciTech Connect

We report on an experimental study of Lyman-..cap alpha.. emission from H(2p) capture processes in collisions between H/sup +/ ions and Na(3s) as well as laser-excited aligned Na(3p) atoms. The impact energy lies between 0.5 and 10 keV. We observe a strong enhancement of capture from Na(3p) over capture from Na(3s), in agreement with recent calculations by R. Allan et al. and W. Fritsch, but at variance with earlier experimental and theoretical results (V. S. Kushawaha et al. and M. Kimura et al.).

Finck, K.; Wang, Y.; Roller-Lutz, Z.; Lutz, H.O.

1988-12-15

431

Seasonal variations of midlatitude mesospheric Na layer and their tidal period perturbations based on full diurnal cycle Na lidar observations of 2002-2008  

NASA Astrophysics Data System (ADS)

The Na lidar facility at Colorado State University (41°N, 105°W) started the full diurnal cycle observations of mesopause region temperature and zonal and meridional winds as well as mesospheric Na density in May 2002. In this paper, monthly means and seasonal variations of the density of mesospheric Na based on lidar observations from May 2002 to December 2008 are reported along with the amplitude and phase of tidal period perturbations. The revealed seasonal behaviors of mesospheric Na layer are generally consistent with published nocturnal climatology, with thick layers and high abundance in winter but thin layers and low abundance near summer. Tidal amplitudes of Na density are large in February-April and August-November with a dominant peak between 85 and 90 km; they are weak in summer months (May-July). The Na density tidal phase profiles, while showing downward progression, show a significant and abrupt phase shift (ideally 180 degrees). The center altitude of this phase shifting (termed switching altitude) is found to coincide with the fractional tidal amplitude (tidal amplitude over diurnal mean) minimum about 2-4 km above the centroid altitude of the associated Na layer. Taking advantage of the established temperature tidal climatology deduced from the same data set, the tidal phase behaviors between temperature and Na density and associated fractional Na density tidal amplitudes are discussed in terms of the theoretical prediction by Gardner and Shelton (1985).

Yuan, Tao; She, C.-Y.; Kawahara, Takuya D.; Krueger, D. A.

2012-06-01

432

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

433

Polarization and collision velocity dependence of associative ionization in cold Na(3 p)-Na(3 p) collisions  

NASA Astrophysics Data System (ADS)

We studied the polarization dependence of the associative ionization (AI) process Na(3 p) + Na(3 p) ? Na{2/+} at collision velocities between 100 and 700 m/s (5 and 200 K), using linearly and circularly polarized light for the excitation. We found that the polarization dependence varies strongly in the collision velocity range under study. At the high end of our scale preparation of both collision partners in the | m j |=1/2 substates yields the highest AI-rate, but at low velocities this ceases being so: the polarization dependence becomes less pronounced and at the low end of our scale the preparation | m j 2|, | m j 2|=3/2, 1/2 is most effective. All cross sections increase strongly at lower velocities. Combined with previous work this maps the detailed polarization dependence from 100 2400 m/s (5-2500 K). From these total results it is concluded that at collision velocities ?500 m/s mainly one molecular potential curve leads to AI, but that this changes considerably at lower collision velocities. The findings are compared with recent theoretical results by Geltman, and we find large discrepancies.

Meijer, H. A. J.

1990-12-01

434

Electron delocalization by polar molecules: Interaction of Na atoms with solid ammonia films studied with MIES and density functional theory  

Microsoft Academic Search

The interaction of Na and NH3 on tungsten was studied with metastable impact electron spectroscopy under UHV conditions. NH3(Na) films were grown at 90(+\\/-10) K on tungsten substrates and exposed to Na(NH3). No Na-induced reaction involving NH3 takes place. At small Na exposures a Na-induced shift of the NH3 spectral features is seen, in parallel with a decrease of the

A. Borodin; O. Höfft; V. Kempter; Y. Ferro; A. Allouche

2004-01-01

435

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