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1

Sluka 8 / 2012 / 746 Vodn ptactvo rybnicn oblasti Hjek  

E-print Network

), polák chocho- lacka (Aythya fuligula) a racek chechtavý (Larus ridibundus). Vzácnými zatou- lanci byli platyrhynchos), Common Pochard (Aythya ferina), Tufted Duck (Aythya fuligula) and Black-headed Gull (Larus cerná (Fulica atra); po ní následovali: kachna divoká (Anas platyrhynchos), polák velký (Aythya ferina

Miksik, Ivan

2

P?KLAD VYUIT TECHNOLOGI GPS A GIS P?I STUDIU KRYOPLANA?NCH TERAS NA LU?N A STUDNI?N HO?E Example of utilization GPS and GIS technologies by study of cryoplanation terraces on the Lu?n Mt. and Studni?n Mt  

Microsoft Academic Search

V poslednch n?kolika letech velmi intenzivn? pronikaj do oblasti vzkumu tvar? povrchu Zem? a geomorfologick analzy technologie GNSS (globln naviga?n satelitn systmy) a GIS (geografick informa?n systm), kter umo?uj velmi efektivn zskvn a zpracovn dat v kvalit? a mnostv, kterch nebylo d?ve mon doshnout. V p?sp?vku jsou uvedeny monosti vyuit t?chto systm? p?i studiu vybranch fenomn? v oblasti Krkono, a

IGOR JAN; KOCINOV MILENA; PRKOV LUCIE

3

\\  

Microsoft Academic Search

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

Gorazd BAJC

4

NaF Documentation  

Cancer.gov

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

5

Transitions in Na IIITransitions in Na III  

Microsoft Academic Search

The work of Blackford and Hibbert (1994 At.Data Nucl.Data Tables58 101-64) has been extended to provide oscillator strengths and transition probabilities for J?J' transitions amongst n = 2 and n = 3 levels of Na III. Configuration interaction wavefunctions, obtained with the code CIV3 in the Breit-Pauli approximation, and with additional correlation effects, have been constructed. Further semi-empirical corrections to

D. McPeake; A. Hibbert

2000-01-01

6

Results from NA57  

E-print Network

The NA57 experiment has measured the production of strange and multi-strange hadrons in heavy-ion collisions at the CERN SPS. After briefly introducing the NA57 apparatus and analysis procedures, we present recent results on strangeness enhancement in Pb-Pb relative to p-Be collisions, on the study of the m_T distributions of strange particles, and on central-to-peripheral nuclear modification factors in Pb-Pb collisions at top SPS energy.

Andrea Dainese

2005-09-30

7

Na Cauda do Cometa  

NASA Astrophysics Data System (ADS)

Quando viam um cometa, os antigos gregos imaginavam uma estrela com uma vasta cabeleira. No toa, a palavra deriva do termo koma, que significa cabelo. Constitudos por fragmentos de gelo e gases, os cometas possuem um ncleo slido, que pode ter vrios quilmetros de dimetro, e uma cauda que sempre aponta na direo contrria ao Sol, devido aos ventos solares. Graas aparncia de pontos luminosos em movimento (ao contrrio de outros astros, que parecem estticos), esses corpos celestes foram interpretados por diferentes povos com muito misticismo, inspirando mitos tanto de boas-novas como de maus pressgios. Conhea algumas dessas histrias:

Voelzke, M. R.

2009-01-01

8

Obesidade infantil: excessos na sociedade  

Microsoft Academic Search

1 Resumo: A obesidade representa um grave problema de sade pblica, caracterizada por um contexto de epidemia mundial. A especificidade da obesidade infantil se estabelece a partir das conseqncias fsicas e emocionais da doena, alm da elevao dos riscos da molstia na vida adulta. Atravs de encontros grupais com familiares de crianas obesas, identificaram-se aspectos relevantes na vida social que

Andria Mendes dos Santos

9

Challenges for Na-ion Negative Electrodes  

E-print Network

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

Chevrier, V. L.

10

Determination of the (Na+) Sternheimer antishielding factor by 23Na NMR spectroscopy on sodium oxide chloride, Na3OCl.  

PubMed

The (Na+) Sternheimer antishielding factor gammainifinity (Na+) was determined by 23Na NMR spectroscopy on sodium oxide-chloride, Na3OCl. The quadrupolar coupling constant of the sodium ion in Na3OCI was determined to QCC = 11.34 MHz, which presents the largest coupling constant of a sodium nucleus observed so far. Applying a simple point charge model, the largest principal value of the electric field gradient at the sodium site was calculated to V(zz) = -6.76762 x 10(20) V/m2. From these values we calculated the (Na+) Sternheimer antishielding factor to gammainifinity (Na+)= -5.36. In sodium oxide, Na2O, we observed an isotropic chemical shift of deltaCS = 55.1 ppm, referenced to 1 M aqueous NaCI (delta = 0 ppm). PMID:10928632

Klsters, G; Jansen, M

2000-07-01

11

Original article Soybean impairs Na  

E-print Network

Original article Soybean impairs Na + -dependent glucose absorption and Cl ­ secretion in porcine -- Recent evidence indicates that soybean, which is widely used in animal nutrition, could directly alter of the study was to investigate the effect of three differently treated soybean prod- ucts on the glucose

Boyer, Edmond

12

BREAKFAST MENU (665 MG NA)  

E-print Network

) Garden Vegetable (80 MG) Beef Broth(140 MG) Cottage Cheese (410 MG) Tossed Salad (O MG) (Oil & Vinegar SODIUM (2000 GM NA) COLD ENTREES: Chicken Caesar Salad (440 MG) (Oil & Vinegar/Lowfat Italian EACH) Baked Potato Chips (170 MG) ACCOMPANIMENTS: (Limit 1 Starch 1 Veg) Green Beans(6 MG) Broccoli

Oliver, Douglas L.

13

NA61/SHINE ion program  

E-print Network

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

Maja Mackowiak for the NA61 Collaboration

2010-09-06

14

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

2009-02-01

15

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 stensen; ystein Mathisen; Fredrik Kiil

1986-01-01

16

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

17

Na+ Tolerance and Na+ Transport in Higher Plants  

PubMed Central

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

TESTER, MARK; DAVENPORT, ROMOLA

2003-01-01

18

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. PMID:20691102

2010-01-01

19

Phase transitions and equations of state for the sodium halides: NaF NaCl, NaBr, and NaI  

NASA Astrophysics Data System (ADS)

Phase changes and equations of state of four sodium halides, NaF, NaCl, NaBr, and NaI, have been studied up to 60 GPa at room temperature with the use of a diamond anvil cell. NaF and NaCl transform from the B1 phase to the B2 phase at 23 GPa and 29 GPa, respectively. At 33 GPa, NaBr transforms from the B1 phase to an unidentified phase with a lower symmetry than the B2 phase. NaI also transforms at 32 GPa to a new phase which seems to have the same structure as that of the high-pressure phase of NaBr. The B2 phase of NaF has bulk modulus K0 = 103 (19) GPa and volume ratio at 1 atm Vo2/Vo1 = 0.811 (0.025), and the B2 phase of NaCl has K0 = 121 (23) GPa and V02/V01 = 0.734 (0.022). The volume change across the transition was estimated to be ?V/V1 ? -10.4% for NaF and -5.8% for NaCl.

Sato-Sorensen, Yosiko

1983-04-01

20

NA  

E-print Network

Information regarding the chemical identity of benzene is located in Table 4-1. Although the term benzol is found in older literature for the commercial product, benzene is the name presently approved by the International Union of Pure and Applied Chemistry (IUPAC), the Chemical Manufacturers Association (CMA), and the American Society for Testing and Materials (ASTM) for the pure product.

unknown authors

21

Aithisg Bhliadhnail Coilltearachd na h-Alba  

E-print Network

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

22

Photoabsorption windows for Na and Na{sub 2}{sup +}  

SciTech Connect

There exist absorption windows (i.e., Cooper-minima) in the photoabsorption cross sections of some atomic systems because of the relative phase shifts between the initial and final state wave functions due to the atomic screening potentials in contrast to the Coulomb potentials. Such window positions are sensitive to the accuracy of the initial and final state wave functions. Using our modified Breit-Pauli R-matrix code, the photoionization cross sections of ground Na are calculated. Our calculated cross sections and minimum position in the low photoelectron energy range (<9 eV) are in excellent agreement with the experimental results. In the high energy range (>9 eV), there is an abnormal bump in the experimental measurements, which is a long-standing experimental puzzle. It is interesting to note that there is also an absorption window in the photoabsorption (i.e., photodissociation) cross sections of Na{sub 2}{sup +}. Such an absorption window provides an answer to the puzzle.

Han Xiaoying [Key Laboratory of Atomic and Molecular Nanosciences of Education Ministry, Department of Physics, Tsinghua University, Beijing 100084 (China); Gao Xiang [Department of Physics, Shanghai Jiao Tong University, Shanghai 200230 (China); Li Jiaming [Department of Physics, Shanghai Jiao Tong University, Shanghai 200230 (China); Key Laboratory of Atomic and Molecular Nanosciences of Education Ministry, Department of Physics, Tsinghua University, Beijing 100084 (China); Voky, Lan; Feautrier, Nicole [LERMA, UMR 8112 du CNRS, Observatoire de Paris, 92915 Meudon Cedex (France)

2006-12-15

23

Na + ,K + ATPase Na + Affinity in Rat Skeletal Muscle Fiber Types  

Microsoft Academic Search

Previous studies in expression systems have found different ion activation of the Na+\\/K+-ATPase isozymes, which suggest that different muscles have different ion affinities. The rate of ATP hydrolysis was used\\u000a to quantify Na+,K+-ATPase activity, and the Na+ affinity of Na+,K+-ATPase was studied in total membranes from rat muscle and purified membranes from muscle with different fiber types. The\\u000a Na+ affinity

Michael Kristensen; Carsten Juel

2010-01-01

24

Relationship between intracellular Na+ concentration and reduced Na+ affinity in Na+,K+-ATPase mutants causing neurological disease.  

PubMed

The neurological disorders familial hemiplegic migraine type 2 (FHM2), alternating hemiplegia of childhood (AHC), and rapid-onset dystonia parkinsonism (RDP) are caused by mutations of Na(+),K(+)-ATPase ?2 and ?3 isoforms, expressed in glial and neuronal cells, respectively. Although these disorders are distinct, they overlap in phenotypical presentation. Two Na(+),K(+)-ATPase mutations, extending the C terminus by either 28 residues ("+28" mutation) or an extra tyrosine ("+Y"), are associated with FHM2 and RDP, respectively. We describe here functional consequences of these and other neurological disease mutations as well as an extension of the C terminus only by a single alanine. The dependence of the mutational effects on the specific ? isoform in which the mutation is introduced was furthermore studied. At the cellular level we have characterized the C-terminal extension mutants and other mutants, addressing the question to what extent they cause a change of the intracellular Na(+) and K(+) concentrations ([Na(+)]i and [K(+)]i) in COS cells. C-terminal extension mutants generally showed dramatically reduced Na(+) affinity without disturbance of K(+) binding, as did other RDP mutants. No phosphorylation from ATP was observed for the +28 mutation of ?2 despite a high expression level. A significant rise of [Na(+)]i and reduction of [K(+)]i was detected in cells expressing mutants with reduced Na(+) affinity and did not require a concomitant reduction of the maximal catalytic turnover rate or expression level. Moreover, two mutations that increase Na(+) affinity were found to reduce [Na(+)]i. It is concluded that the Na(+) affinity of the Na(+),K(+)-ATPase is an important determinant of [Na(+)]i. PMID:24356962

Toustrup-Jensen, Mads S; Einholm, Anja P; Schack, Vivien R; Nielsen, Hang N; Holm, Rikke; Sobrido, Mara-Jess; Andersen, Jens P; Clausen, Torben; Vilsen, Bente

2014-02-01

25

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

26

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

PubMed Central

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

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

2014-01-01

27

UltraHigh NA Structured Illumination Microscopy  

Microsoft Academic Search

We measure the three-dimensional point-spread function and compare the resolution of three high numerical aperture objectives (NA) in a structured illumination fluorescence microscope using three-dimensional images of single quantum dots. Compared with conventional 1.30 and 1.42 NA objectives, the ultra-high 1.65 NA TIRF objectives offer significantly improved lateral spatial resolution of better than 75 nm using 488 nm excitation.

Michael Beversluis; Stephan Stranick

2007-01-01

28

Modeling Na clusters in Ar matrices  

Microsoft Academic Search

We present a microscopic model for Na clusters embedded in raregas matrices. The valence electrons of the Na cluster are described by time-dependent density-functional theory at the level of the local-density approximation (LDA). Particular attention is paid to the semi-classical picture in terms of Vlasov-LDA. The Na+ ions and Ar atoms are handled as classical particles whereby the Ar atoms

F. Fehrer; M. Mundt; P.-G. Reinhard; E. Suraud

2005-01-01

29

Painful Na-channelopathies: an expanding universe.  

PubMed

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

Waxman, Stephen G

2013-07-01

30

Cerebral Na concentration, Na appetite and thirst of sheep: influence of somatostatin and losartan.  

PubMed

Na and water intakes of Na-depleted sheep are influenced by changes in cerebral Na concentration. The effect of intracerebroventricular infusion of somatostatin or losartan, the ANG II type 1 receptor antagonist, on the Na appetite and thirst of Na-depleted sheep during infusions that decrease (intracerebroventricular hypertonic mannitol) or increase (intracerebroventricular or systemic hypertonic NaCl) cerebral Na concentration was investigated. Na intake was increased but water intake was unchanged during intracerebroventricular infusion of hypertonic mannitol. The increased Na appetite caused by intracerebroventricular infusion of hypertonic mannitol was decreased by concurrent intracerebroventricular infusion of either somatostatin or losartan, with somatostatin being most effective. Water intake was increased during intracerebroventricular infusion of hypertonic mannitol and somatostatin. Na intake was decreased and water intake was increased during systemic or intracerebroventricular infusion of hypertonic NaCl. Intracerebroventricular infusion of losartan blocked both (Na and water intake), whereas somatostatin did not influence either of these changes in intake. The results further consolidate a role for somatostatin and ANG II in the central mechanisms controlling Na appetite and thirst of sheep. PMID:11171646

Weisinger, R S; Blair-West, J R; Burns, P; Denton, D A; Purcell, B

2001-03-01

31

Epithelial Na(+) channels are regulated by flow.  

PubMed

Na(+) absorption in the renal cortical collecting duct (CCD) is mediated by apical epithelial Na(+) channels (ENaCs). The CCD is subject to continuous variations in intraluminal flow rate that we speculate alters hydrostatic pressure, membrane stretch, and shear stress. Although ENaCs share limited sequence homology with putative mechanosensitive ion channels in Caenorhabditis elegans, controversy exists as to whether ENaCs are regulated by biomechanical forces. We examined the effect of varying the rate of fluid flow on whole cell Na(+) currents (I(Na)) in oocytes expressing mouse alpha,beta,gamma-ENaC (mENaC) and on net Na(+) absorption in microperfused rabbit CCDs. Oocytes injected with mENaC but not water responded to the initiation of superfusate flow (to 4-6 ml/min) with a reversible threefold stimulation of I(Na) without a change in reversal potential. The increase in I(Na) was variable among oocytes. CCDs responded to a threefold increase in rate of luminal flow with a twofold increase in the rate of net Na(+) absorption. An increase in luminal viscosity achieved by addition of 5% dextran to the luminal perfusate did not alter the rate of net Na(+) absorption, suggesting that shear stress does not influence Na(+) transport in the CCD. In sum, our data suggest that flow stimulation of ENaC activity and Na(+) absorption is mediated by an increase in hydrostatic pressure and/or membrane stretch. We propose that intraluminal flow rate may be an important regulator of channel activity in the CCD. PMID:11352841

Satlin, L M; Sheng, S; Woda, C B; Kleyman, T R

2001-06-01

32

Interfering Rydberg wave packets in Na  

Microsoft Academic Search

This paper presents an experimental and theoretical analysis of quantum interference between Rydberg wave packets in Na. Pairs of phase-locked wave packets manipulate the total orbital angular momentum of Na Rydberg atoms. Initially, the wave packet is composed of a superposition of s and d Rydberg series. Exploitation of the difference between the quantum defects of the two series allows

R. E. Carley; E. D. Bolat; R. S. Minns; R. Patel; H. H. Fielding

2005-01-01

33

Regulation of Na+ fluxes in plants  

PubMed Central

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

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

2014-01-01

34

Substrate interactions of the electroneutral Na+-coupled inorganic phosphate cotransporter (NaPi-IIc)  

PubMed Central

The SLC34 solute carrier family comprises the electrogenic NaPi-IIa/b and the electroneutral NaPi-IIc, which display Na+ : Pi cotransport stoichiometries of 3 : 1 and 2 : 1, respectively. We previously proposed that NaPi-IIc lacks one of the three Na+ interaction sites hypothesised for the electrogenic isoforms, but, unlike NaPi-IIa/b, its substrate binding order is undetermined. By expressing NaPi-IIc in Xenopus oocytes, isotope influx and efflux assays gave results consistent with Na+ being the first and last substrate to bind. To further investigate substrate interactions, we applied a fluorometry-based technique that uses site-specific labelling with a fluorophore to characterize substrate-induced conformational changes. A novel Cys was introduced in the third extracellular loop of NaPi-IIc that could be labelled with a reporter fluorophore (MTS-TAMRA). Although labelling resulted in suppression of cotransport as previously reported for the electrogenic isoforms, changes in fluorescence were induced by changes in extracellular Na+ concentration in the absence of Pi and by changes in extracellular Pi concentration in presence of Na+. These data, combined with 32P uptake data, also support a binding scheme in which Na+ is the first substrate to interact. Moreover, the apparent Pi affinity from fluorometry agreed with that from 32P uptake, confirming the applicability of the fluorometric technique for kinetic studies of electroneutral carriers. Analysis of the fluorescence data showed that like the electrogenic NaPi-IIb, 2 Na+ ions interact cooperatively with NaPi-IIc before Pi binding, which implies that only one of these is translocated. This result provides compelling evidence that SLC34 proteins share common motifs for substrate interaction and that cotransport and substrate binding stoichiometries are not necessarily equivalent. PMID:19596895

Ghezzi, Chiara; Murer, Heini; Forster, Ian C

2009-01-01

35

On the formation of transient (Na19)2 and (Na20)2 cluster dimers from molecular dynamics simulations  

Microsoft Academic Search

By using distance-dependent tight-binding molecular dynamics simulations, we discuss the possibilities to form (Na19)2 and (Na20)2 cluster dimers in sodium cluster-cluster collisions. In the case of Na19+Na19, we show that the formation of a prolate dimer-like (Na19)2 may depend on the initial relative orientations of the colliding clusters. A similar study for Na20+Na20 does not seen to show the same

F. S. Zhang; F. Spiegelmann; E. Suraud; V. Frayss; R. Poteau; R. Glowinski; F. Chatelin

1994-01-01

36

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

NASA Astrophysics Data System (ADS)

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

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

1986-02-01

37

Race and sex differences in erythrocyte Na+, K+, and Na+-K+-adenosine triphosphatase.  

PubMed Central

Several reports indicate that erythrocytes (RBCs) from blacks and men have higher sodium concentrations than those from whites and women. One possible mechanism to explain this finding is a difference in the activity of Na+-K+-ATPase. To explore this possibility, we have studied the Na+ and K+ kinetics of RBC Na+-K+-ATPase and RBC Na+ and K+ concentrations in 37 normotensive blacks and whites, both males and females. The maximal initial reaction velocity (Vmax) values for RBC Na+-K+-ATPase were lower in blacks and men as compared with whites and women. Higher RBC Na+ levels were observed in blacks and males vs. whites and females. Significant inverse correlations were noted between the Na+-K+-ATPase activity and RBC Na+ concentrations. These findings indicate that cellular Na+ homeostasis is different in blacks and men as compared with whites and women. Since higher RBC Na+ concentrations have also been observed in patients with essential hypertension as compared with normotensive subjects, the higher intracellular Na+ concentrations in blacks and men may contribute to the greater predisposition of these groups to essential hypertension. PMID:2989333

Lasker, N; Hopp, L; Grossman, S; Bamforth, R; Aviv, A

1985-01-01

38

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

NASA Astrophysics Data System (ADS)

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

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

1996-07-01

39

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

40

Gasotransmitters: Novel Regulators of Epithelial Na+ Transport?  

PubMed Central

The vectorial transport of Na+ across epithelia is crucial for the maintenance of Na+ and water homeostasis in organs such as the kidneys, lung, or intestine. Dysregulated Na+ transport processes are associated with various human diseases such as hypertension, the salt-wasting syndrome pseudohypoaldosteronism type 1, pulmonary edema, cystic fibrosis, or intestinal disorders, which indicate that a precise regulation of epithelial Na+ transport is essential. Novel regulatory signaling molecules are gasotransmitters. There are currently three known gasotransmitters: nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S). These molecules are endogenously produced in mammalian cells by specific enzymes and have been shown to regulate various physiological processes. There is a growing body of evidence which indicates that gasotransmitters may also regulate Na+ transport across epithelia. This review will summarize the available data concerning NO, CO, and H2S dependent regulation of epithelial Na+ transport processes and will discuss whether or not these mediators can be considered as true physiological regulators of epithelial Na+ transport biology. PMID:22509167

Althaus, Mike

2012-01-01

41

Gasotransmitters: novel regulators of epithelial na(+) transport?  

PubMed

The vectorial transport of Na(+) across epithelia is crucial for the maintenance of Na(+) and water homeostasis in organs such as the kidneys, lung, or intestine. Dysregulated Na(+) transport processes are associated with various human diseases such as hypertension, the salt-wasting syndrome pseudohypoaldosteronism type 1, pulmonary edema, cystic fibrosis, or intestinal disorders, which indicate that a precise regulation of epithelial Na(+) transport is essential. Novel regulatory signaling molecules are gasotransmitters. There are currently three known gasotransmitters: nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H(2)S). These molecules are endogenously produced in mammalian cells by specific enzymes and have been shown to regulate various physiological processes. There is a growing body of evidence which indicates that gasotransmitters may also regulate Na(+) transport across epithelia. This review will summarize the available data concerning NO, CO, and H(2)S dependent regulation of epithelial Na(+) transport processes and will discuss whether or not these mediators can be considered as true physiological regulators of epithelial Na(+) transport biology. PMID:22509167

Althaus, Mike

2012-01-01

42

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

E-print Network

The voltage-gated Na channel NaVBP has a role in motility, chemotaxis, and pH homeostasis, is a voltage-gated Na channel potentiated by alkaline pH. NaVBP has roles in motility, chemotaxis, and pH homeostasis at high pH. Reduced motility of bacteria lacking functional NaVBP was reversed by restoration

Clapham, David E.

43

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

PubMed

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

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

2013-07-01

44

Catalysis of Na+ permeation in the bacterial sodium channel NaVAb  

PubMed Central

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

Chakrabarti, Nilmadhab; Ing, Christopher; Payandeh, Jian; Zheng, Ning; Catterall, William A.; Pomes, Regis

2013-01-01

45

Rastafari : identidade e hibridismo cultural na Jamaica, 1930-1981.  

E-print Network

??Tese(doutorado)Universidade de Braslia/Departamento de Histria, 2006. Na Jamaica, o passado colonial baseado na plantation escravista, produziu uma sociedade estratificada na qual a cor mais clara (more)

Rabelo, Danilo

2006-01-01

46

An Update on NA50 and LUCIFER  

E-print Network

Recent analysis of both new (1998) and old (1995,1996) data obtained by the NA50 Collaboration on J/Psi suppression in Pb+Pb are examined in light of our already existing calculations with the relativistic heavy ion simulation LUCIFER. In particular we comment on the unexplained change of transverse energy scale by NA50 and the apparent disappearance from the data of discontinuities in the suppression with transverse energy.

D. E. Kahana; S. H. Kahana

1999-08-20

47

An Update on NA50 and LUCIFER  

E-print Network

Recent analysis of both new (1998) and old (1995,1996) data obtained by the NA50 Collaboration on J/Psi suppression in Pb+Pb are examined in light of our already existing calculations with the relativistic heavy ion simulation LUCIFER. In particular we comment on the unexplained change of transverse energy scale by NA50 and the apparent disappearance from the data of discontinuities in the suppression with transverse energy.

Kahana, D E

1999-01-01

48

Kako natan?na je lahko transkripcija  

E-print Network

analysis. Ur. Deborah Schiffrin, Deborah Tannen, Heidi E. Hamilton. Oxford: Blackwell. 321348. Michael Alexander Kirkwood HALLIDAY, 1998: An Introduction To Functional Grammar. 6th impression. London. 292308. Klaus von HEUSINGER, 1999: Intonation... 2000. 6 Glej dalje zgled mh mh mh. 163 Kako natan?na je lahko transkripcija Tak je na primer Hallidayev pristop (Halliday 1998: 292308) k pojmovanju intonacije oz. tonskega poteka, ki je predmet avtorjevih raziskav poleg ritma in tona. Za...

Ivi?, Mira Krajnc

2010-02-01

49

Electrogenic Na +\\/Ca 2+-exchange of nerve and muscle cells  

Microsoft Academic Search

The plasma membrane Na+\\/Ca2+-exchanger is a bi-directional electrogenic (3Na+:1Ca2+) and voltage-sensitive ion transport mechanism, which is mainly responsible for Ca2+-extrusion. The Na+-gradient, required for normal mode operation, is created by the Na+-pump, which is also electrogenic (3Na+:2K+) and voltage-sensitive. The Na+\\/Ca2+-exchanger operational modes are very similar to those of the Na+-pump, except that the uncoupled flux (Na+-influx or -efflux?) is

Tams L. Trk

2007-01-01

50

Vibrational signatures of sodiated oligopeptides (GG-Na+, GGG-Na+, AA-Na+ and AAA-Na+) in the gas phase  

NASA Astrophysics Data System (ADS)

The structures of the sodium complexes of oligoglycines (GG-Na+, GGG-Na+) and oligoalanines (AA-Na+, AAA-Na+) have been studied by infrared spectroscopy in the gas phase. Two different experimental set-ups have been used to generate, trap and analyze the ions. In the first, the complexes were generated by MALDI and analyzed in the cell of a home built FT-ICR mass spectrometer. In the second an external electrospray source was coupled to a Paul type ion trap. Following their trapping, the ions are irradiated in both cases with intense, tunable infrared light in the 1000-2000 cm-1 range, leading to sodium ion detachment and ion fragmentation via the absorption of multiple photons. The resulting experimental spectra are compared to theoretical linear absorption spectra to assign structures. In agreement with calculations, peptide attachment to Na+ is found to have a strong structuring effect: the lowest energy structures involve binding of all carbonyl oxygens to the cation. Detailed comparison of experimental and computed spectra shows that the IRMPD spectroscopy of such gaseous ions allows the differentiation between structures which do not have the same number of carbonyl oxygens bound to Na+, and structures in which the peptide is either wrapped around the ion or capped by it.

Balaj, O. P.; Kapota, C.; Lemaire, J.; Ohanessian, G.

2008-02-01

51

Modeling Na clusters in Ar matrices  

E-print Network

We present a microscopic model for Na clusters embedded in raregas matrices. The valence electrons of the Na cluster are described by time-dependent density-functional theory at the level of the local-density approximation (LDA). Particular attention is paid to the semi-classical picture in terms of Vlasov-LDA. The Na ions and Argon atoms are handled as classical particles whereby the Ar atoms carry two degrees of freedom, position and dipole polarization. The interaction between Na ions and electrons is mediated through local pseudo-potentials. The coupling to the Ar atoms is described by (long-range) polarization potentials and (short-range) repulsive cores. The ingredients are taken from elsewhere developed standards. A final fine-tuning is performed using the NaAr molecule as benchmark. The model is then applied to embedded systems Na8ArN. By close comparison with quantum-mechanical results, we explore the capability of the Vlasov-LDA to describe such embedded clusters. We show that one can obtain a reaso...

Fehrer, F; Reinhard, P G; Suraud, E

2005-01-01

52

Modeling Na clusters in Ar matrices  

NASA Astrophysics Data System (ADS)

We present a microscopic model for Na clusters embedded in raregas matrices. The valence electrons of the Na cluster are described by time-dependent density-functional theory at the level of the local-density approximation (LDA). Particular attention is paid to the semi-classical picture in terms of Vlasov-LDA. The Na+ ions and Ar atoms are handled as classical particles whereby the Ar atoms carry two degrees of freedom, position and dipole polarization. The interaction between Na+ ions and electrons is mediated through local pseudo-potentials. The coupling to the Ar atoms is described by (long-range) polarization potentials and (short-range) repulsive cores. The ingredients are taken from elsewhere developed standards. A final fine-tuning is performed using the NaAr molecule as benchmark. The model is then applied to embedded systems Na8ArN. By close comparison with quantum-mechanical results, we explore the capability of the Vlasov-LDA to describe such embedded clusters. We show that one can obtain a reasonable description by appropriate adjustments in the fine-tuning phase of the model.

Fehrer, F.; Mundt, M.; Reinhard, P.-G.; Suraud, E.

2005-07-01

53

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

54

Determination of Na 2O from sodium aluminate NaAlO 2  

Microsoft Academic Search

The aim of the work was to find a suitable method and conditions for determining Na2O wt.% from NaAlO2. Problems were encountered while titrating NaAlO2 with hydrochloric acid. The problematic area was the pH range 410 where aluminum precipitates as hydroxides. The different species of the aluminate solution were determined using potentiometric and complexometric titrations. The equivalent point of the

Teemu Nykki; Anttila Raimo; Permki Paavo; Kurikka Antero; Nikula Pivi

2000-01-01

55

Na+, K+, and Cl- transport in resting pancreatic acinar cells  

PubMed Central

To understand the role of Na+, K+, and Cl- transporters in fluid and electrolyte secretion by pancreatic acinar cells, we studied the relationship between them in resting and stimulated cells. Measurements of [Cl-]i in resting cells showed that in HCO3(-)-buffered medium [Cl- ]i and Cl- fluxes are dominated by the Cl-/HCO3- exchanger. In the absence of HCO3-, [Cl-]i is regulated by NaCl and NaK2Cl cotransport systems. Measurements of [Na+]i showed that the Na(+)-coupled Cl- transporters contributed to the regulation of [Na+]i, but the major Na+ influx pathway in resting pancreatic acinar cells is the Na+/H+ exchanger. 86Rb influx measurements revealed that > 95% of K+ influx is mediated by the Na+ pump and the NaK2Cl cotransporter. In resting cells, the two transporters appear to be coupled through [K+]i in that inhibition of either transporter had small effect on 86Rb uptake, but inhibition of both transporters largely prevented 86Rb uptake. Another form of coupling occurs between the Na+ influx transporters and the Na+ pump. Thus, inhibition of NaK2Cl cotransport increased Na+ influx by the Na+/H+ exchanger to fuel the Na+ pump. Similarly, inhibition of Na+/H+ exchange increased the activity of the NaK2Cl cotransporter. The combined measurements of [Na+]i and 86Rb influx indicate that the Na+/H+ exchanger contributes twice more than the NaK2Cl cotransporter and three times more than the NaCl cotransporter and a tetraethylammonium-sensitive channel to Na+ influx in resting cells. These findings were used to develop a model for the relationship between the transporters in resting pancreatic acinar cells. PMID:8786358

1995-01-01

56

FXYD Proteins Stabilize Na,K-ATPase  

PubMed Central

FXYD proteins are a family of seven small regulatory proteins, expressed in a tissue-specific manner, that associate with Na,K-ATPase as subsidiary subunits and modulate kinetic properties. This study describes an additional property of FXYD proteins as stabilizers of Na,K-ATPase. FXYD1 (phospholemman), FXYD2 (? subunit), and FXYD4 (CHIF) have been expressed in Escherichia coli and purified. These FXYD proteins associate spontaneously in vitro with detergent-soluble purified recombinant human Na,K-ATPase (?1?1) to form ?1?1FXYD complexes. Compared with the control (?1?1), all three FXYD proteins strongly protect Na,K-ATPase activity against inactivation by heating or excess detergent (C12E8), with effectiveness FXYD1 > FXYD2 ? FXYD4. Heating also inactivates E1 ? E2 conformational changes and cation occlusion, and FXYD1 protects strongly. Incubation of ?1?1 or ?1?1FXYD complexes with guanidinium chloride (up to 6 m) causes protein unfolding, detected by changes in protein fluorescence, but FXYD proteins do not protect. Thus, general protein denaturation is not the cause of thermally mediated or detergent-mediated inactivation. By contrast, the experiments show that displacement of specifically bound phosphatidylserine is the primary cause of thermally mediated or detergent-mediated inactivation, and FXYD proteins stabilize phosphatidylserine-Na,K-ATPase interactions. Phosphatidylserine probably binds near trans-membrane segments M9 of the ? subunit and the FXYD protein, which are in proximity. FXYD1, FXYD2, and FXYD4 co-expressed in HeLa cells with rat ?1 protect strongly against thermal inactivation. Stabilization of Na,K-ATPase by three FXYD proteins in a mammalian cell membrane, as well the purified recombinant Na,K-ATPase, suggests that stabilization is a general property of FXYD proteins, consistent with a significant biological function. PMID:21228272

Mishra, Neeraj Kumar; Peleg, Yoav; Cirri, Erica; Belogus, Talya; Lifshitz, Yael; Voelker, Dennis R.; Apell, Hans-Juergen; Garty, Haim; Karlish, Steven J. D.

2011-01-01

57

Reconstitution of intestinal Na(+)-phosphate cotransporter.  

PubMed

The rabbit intestinal brush-border membrane Na(+)-phosphate cotransporter was purified from sodium dodecyl sulfate (SDS)-brush-border membrane vesicles (BBMV) protein (SDS-treated Ca(2+)-precipitated BBMV) by a three-column chromatography protocol. The purification included a preparative scale chromatofocusing chromatography column over the pH range from 7.4 to 4 after solubilization in 3-[(3-cholamidopropyl)-diamethylammonia]-1-propanesulfonate (CHAPS), a chromatofocusing column over the pH range from 5.6 to 4 after solubilization in n-octyl glucoside, and gel filtration chromatography on a Sephacryl S-200 column. Verification of Na(+)-phosphate cotransporter purification involved substrate affinities, substrate stoichiometry, and inhibitor sensitivity after proteoliposome reconstitution and SDS-polyacrylamide gel electrophoresis (PAGE). After gel filtration Na(+)-dependent phosphate uptake was 3,300-fold enriched compared with the cell homogenate. A single 130-kDa polypeptide was visualized by SDS-PAGE under reducing conditions using silver stain. The coenrichment of this 130-kDa polypeptide and proteoliposome reconstituted Na(+)-dependent phosphate uptake suggest that the intestinal brush-border membrane Na(+)-phosphate cotransporter has been purified and proteoliposome reconstituted. PMID:8476048

Peerce, B E; Cedilote, M; Seifert, S; Levine, R; Kiesling, C; Clarke, R D

1993-04-01

58

Brief Communications Inwardly Permeating Na Ions Generate the Voltage  

E-print Network

Brief Communications Inwardly Permeating Na Ions Generate the Voltage Dependence of Resurgent Na measured voltage-clamped currents in different Na gradients to test the role of permeating ionsNaionsoccupyingtheexternalpore.Thelackofvoltagesensitivityoftheblockingproteinsuggeststhattheblocker'sbinding site lies outside the membrane field, in the permeation pathway. Introduction Resurgent Na current

Raman, Indira M.

59

Interpretation of the photoelectron spectra of superalkali species: Na3O and Na3O-  

NASA Astrophysics Data System (ADS)

Recently measured photoelectron spectra of the Na3O- anion have been interpreted with the aid of ab initio electron propagator calculations. As in the case of the Li3O-, we propose that the photoionization of ground and excited neutral states, in a sequential two photon absorption mechanism, plays a role in the interpretation of the observed spectrum. The lowest vertical electron detachment energy of Na3O- corresponds to a Dyson orbital that is composed chiefly of diffuse Na s functions and connects a D3h singlet anion to an uncharged species with the same point group. Electron binding energies of isomers of the anion with different point groups or multiplicities have been considered. The relative magnitudes of the ionization energies of the neutral Li3O and Na3O species are also discussed. Whereas the most recent experimental data hold that Na3O has the higher ionization energy, this work asserts the opposite trend.

Zein, S.; Ortiz, J. V.

2012-06-01

60

FLORISTICK POMERY, ICHTYOFAUNA A MAKROZOOBENTOS AKO POTRAVN BZA RB V ?AOBNCH JAMCH LATORICE V OBLASTI ?I?AROVCE - BEA  

Microsoft Academic Search

In July 2005 the fish communities inhabiting 6 artificial pools were investigated in the floodplain along the lower reaches of the River Latorica between Bea and ?i?arovce villages. The pools were rather shallow with submersed macrophytes. The macroinvertebrate communities represent the good trophical base for the most of fish species. In the habitats under study, evidence has been obtained of

PAVOL BALZS; PETER MANKO

61

Na+/K+-ATPase: Activity and inhibition  

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

62

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

PubMed

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

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

1990-11-01

63

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

PubMed

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

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

1996-11-01

64

Optics and Interferometry with Na2 Molecules  

Microsoft Academic Search

We have produced an intense, pure beam of sodium molecules (Na2) by using light forces to separate the atomic and molecular species in a seeded supersonic beam. We used diffraction from a microfabricated grating to study the atomic and molecular sodium in the beam. Using three of these gratings, we constructed a molecule interferometer with fully separated beams and high

Michael S. Chapman; Christopher R. Ekstrom; Troy D. Hammond; Richard A. Rubenstein; Jrg Schmiedmayer; Stefan Wehinger; David E. Pritchard

1995-01-01

65

Binding to Na+ exchanger regulatory factor 2  

E-print Network

Binding to Na+ /H+ exchanger regulatory factor 2 (NHERF2) affects trafficking and function in order to colonize and multiply in the human gut. Map, EspI and NleH1 are conserved EPEC effectors the trafficking of EspI to the Golgi and diminished the anti-apoptotic activity of NleH1. The binding of multiple

Hall, Randy A

66

master's degree NaNotechNology  

E-print Network

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

Twente, Universiteit

67

IV laser spectroscopy on NaI  

NASA Astrophysics Data System (ADS)

Using frequency-double laser radiation, fragmentary rotational fine structure was observed and assigned in the electronic transition 0 + - X 1? + of NaI for the first time. Adopting the semiclassical model of Child for predissociating states, molecular parameters were determined for the limiting diabatic and adiabatc states above the dissociation energy.

Schaefer, S. H.; Bender, D.; Tiemann, E.

1982-10-01

68

Single ionization of Na(3s) and Na*(3p) by low energy ion impact  

NASA Astrophysics Data System (ADS)

Single ionization cross sections for He2+ and O6+ impact on Na*(3p) in the 2-10 keV amu-1 energy range have been measured using recoil-ion momentum spectroscopy of cold Na atoms. The present results are compared with our previous data on Na(3s). It is found that ionization of these weakly bound alkali systems yields larger cross sections than predicted from scaling laws derived from H and He targets. Also information on the ejected electron momenta could be obtained from the recoil spectra.

Knoop, S.; Hasan, V. G.; Ott, H.; Morgenstern, R.; Hoekstra, R.

2006-04-01

69

Luminescence of NaCl:Tl and NaCl:In at high pressure  

NASA Astrophysics Data System (ADS)

The effects of pressure up to 40 kbar and temperatures down to 100 K on the intensity and lifetime of NaCa:Tl+ and NaCl:In has been studied. A kinetic model describing these luminescent properties has been proposed. The 3Tlu level is in thermal equilibrium with 3Alu. Both 3Tlu and 3Alu have nonradiative pathways to the ground state 1Alg. In addition 3Tlu is radiatively coupled to the ground state. Increasing pressure increases the radiative rate from 3Tlu to 1Alg and has no effect on the equilibrium between 3Tlu and 3Alu. The back feeding rate from 3Alu to 3Tlu is temperature sensitive for NaCl:Tl but not for NaCl:In.

Littman, J. E.; Drickamer, H. G.

1982-03-01

70

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

PubMed Central

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

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

1998-01-01

71

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

NASA Technical Reports Server (NTRS)

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

Cherng, Jing-Yih; Bennion, Douglas N.

1987-01-01

72

Amino group modification of (Na + +K + )ATPase  

Microsoft Academic Search

The effects of three amino group reagents on the activity of (Na++K+)-ATPase3 and its component K+-stimulatedp-nitrophenylphosphatase activity from rabbit kidney outer medulla have been studied. All three reagents cause inactivation of the enzyme. Modification of amino groups with trinitrobenzene sulfonic acid yields kinetics of inactivation of both activities, which depend on the type and concentration of the ligands present. In

J. J. H. H. M. De Pont; S. E. Emst-De Vries; S. L. Bonting

1984-01-01

73

LA GACETA 107 RESE ~NA DE LIBROS  

E-print Network

LA GACETA 107 RESE ~NA DE LIBROS DYNAMICAL SYSTEMS WITH APPLICATIONS USING MAPPLE Autor: Stephen libro publicado por alg´un autor ruso, no siempre f´acil de desci- frar. En los ´ultimos a~nos, sin los muchos libros que existen en el mercado y que van apareciendo cada d´ia. Una buena elecci´on ser

Rey Juan Carlos, Universidad

74

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

75

An enhancement to the NA4 gear vibration diagnostic parameter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

76

An enhancement to the NA4 gear vibration diagnostic parameter  

NASA Astrophysics Data System (ADS)

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

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

1994-07-01

77

Progress of the NA62 RICH detector  

NASA Astrophysics Data System (ADS)

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

Lenti, Massimo

2014-01-01

78

Resonances production from the NA60 experiment  

NASA Astrophysics Data System (ADS)

The NA60 experiment at the CERN SPS has studied light vector meson production in In-In collisions at 158A GeV. The ? meson was detected via both the K+K- and the ?+?- decay channels. The yields and inverse slope parameters of the mT spectra observed in the two channels are compatible within errors, different from the large discrepancies seen in Pb-Pb collisions between the hadronic (NA49) and dimuon (NA50) decay channels. In the invariant mass region 0.2 < M?? < 2.6 GeV, a strong excess of pairs above the sources that describe the mass spectrum in p-A collisions is observed. The mass spectrum for M?? < 1 GeV is consistent with a dominant contribution from the pion annihilation process ? + ? ? ? ? ?+?-. For M?? > 1 GeV, the excess is found to be prompt, with remarkable differences with respect to the Drell-Yan process. The Teff slope parameter, extracted from the transverse mass spectra, shows a rise with mass up to the ?, followed by a sudden decline for higher masses. The former is consistent with radial flow of a hadronic source, while the latter suggests a dominantly partonic emission source.

De Falco, A.

2012-11-01

79

Determining Neutron Multiplicity in MoNA  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array, located at the NSCL at Michigan State University, is used in conjunction with the MSU/FSU Sweeper Magnet to study the breakup of neutron-rich nuclei. Fragmentation reactions create particle-unstable nuclei near the neutron dripline which spontaneously breakup by the decay of one or two neutrons with energies that reflect the nuclear structure of unbound excited and ground states. The neutrons continue forward into MoNA where their position and time are recorded, and the charged fragments' position and energy are measured by the array of detectors following the Sweeper Magnet. The neutron decay energies can then be determined using kinematic reconstruction of the breakup. It is important to distinguish between one- and two-neutron decays in MoNA. We have therefore developed an algorithm that helps determine neutron multiplicity, based on energy and momentum conservation restrictions for single neutrons scattering multiple times in MoNA. Results of this approach to the analysis of ^12Be and ^11Be decay will be presented.

Gillette, J.; Gardner, M.; Reed, A.; Rogers, W. F.; Mosby, S.

2007-10-01

80

A 23Na magic angle spinning nuclear magnetic resonance, XANES, and high-temperature X-ray diffraction study of NaUO3, Na4UO5, and Na2U2O7.  

PubMed

The valence state of uranium has been confirmed for the three sodium uranates NaU(V)O3/[Rn](5f(1)), Na4U(VI)O5/[Rn](5f(0)), and Na2U(VI)2O7/[Rn](5f(0)), using X-ray absorption near-edge structure (XANES) spectroscopy. Solid-state (23)Na magic angle spinning nuclear magnetic resonance (MAS NMR) measurements have been performed for the first time, yielding chemical shifts at -29.1 (NaUO3), 15.1 (Na4UO5), and -14.1 and -19 ppm (Na1 8-fold coordinated and Na2 7-fold coordinated in Na2U2O7), respectively. The [Rn]5f(1) electronic structure of uranium in NaUO3 causes a paramagnetic shift in comparison to Na4UO5 and Na2U2O7, where the electronic structure is [Rn]5f(0). A (23)Na multi quantum magic angle spinning (MQMAS) study on Na2U2O7 has confirmed a monoclinic rather than rhombohedral structure with evidence for two distinct Na sites. DFT calculations of the NMR parameters on the nonmagnetic compounds Na4UO5 and Na2U2O7 have permitted the differentiation between the two Na sites of the Na2U2O7 structure. The linear thermal expansion coefficients of all three compounds have been determined using high-temperature X-ray diffraction: ?a = 22.7 10(-6) K(-1), ?b = 12.9 10(-6) K(-1), ?c = 16.2 10(-6) K(-1), and ?vol = 52.8 10(-6) K(-1) for NaUO3 in the range 298-1273 K; ?a = 37.1 10(-6) K(-1), ?c = 6.2 10(-6) K(-1), and ?vol = 81.8 10(-6) K(-1) for Na4UO5 in the range 298-1073 K; ?a = 6.7 10(-6) K(-1), ?b = 14.4 10(-6) K(-1), ?c = 26.8 10(-6) K(-1), ?? = -7.8 10(-6) K(-1), and ?vol = -217.6 10(-6) K(-1) for Na2U2O7 in the range 298-573 K. The ? to ? phase transition reported for the last compound above about 600 K was not observed in the present studies, either by high-temperature X-ray diffraction or by differential scanning calorimetry. PMID:24350659

Smith, A L; Raison, P E; Martel, L; Charpentier, T; Farnan, I; Prieur, D; Hennig, C; Scheinost, A C; Konings, R J M; Cheetham, A K

2014-01-01

81

Na+/H+ and Na+/NH+4 activities of zebrafish NHE3b expressed in Xenopus oocytes.  

PubMed

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

Ito, Yusuke; Kato, Akira; Hirata, Taku; Hirose, Shigehisa; Romero, Michael F

2014-03-01

82

Angiotensin II-induced hypertension increases plasma membrane Na pump activity by enhancing Na entry in rat thick ascending limbs.  

PubMed

Thick ascending limbs (TAL) reabsorb 30% of the filtered NaCl load. Na enters the cells via apical Na-K-2Cl cotransporters and Na/H exchangers and exits via basolateral Na pumps. Chronic angiotensin II (ANG II) infusion increases net TAL Na transport and Na apical entry; however, little is known about its effects on the basolateral Na pump. We hypothesized that in rat TALs Na pump activity is enhanced by ANG II-infusion, a model of ANG II-induced hypertension. Rats were infused with 200 ngkg(-1)min(-1) ANG II or vehicle for 7 days, and TAL suspensions were obtained. We studied plasma membrane Na pump activity by measuring changes in 1) intracellular Na (Nai) induced by ouabain; and 2) ouabain-sensitive oxygen consumption (QO2). We found that the ouabain-sensitive rise in Nai in TALs from ANG II-infused rats was 12.8 0.4 arbitrary fluorescent units (AFU)mg(-1)min(-1) compared with only 9.9 1.1 AFUmg(-1)min(-1) in controls (P < 0.024). Ouabain-sensitive oxygen consumption was 17 5% (P < 0.043) greater in tubules from ANG II-treated than vehicle rats. ANG II infusion did not alter total Na pump expression, the number of Na pumps in the plasma membrane, or the affinity for Na. When furosemide (1.1 mgkg(-1)day(-1)) was coinfused with ANG II, no increase in plasma membrane Na pump activity was observed. We concluded that in ANG II-induced hypertension Na pump activity is increased in the plasma membrane of TALs and that this increase is caused by the chronically enhanced Na entry occurring in this model. PMID:23986517

Gonzalez-Vicente, Agustin; Garvin, Jeffrey L

2013-11-01

83

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

2013-07-01

84

Advanced Intermediate-Temperature Na-S Battery  

SciTech Connect

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

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

2013-01-01

85

Influence of Salt Purity on Na+ and Palmitic Acid Interactions  

E-print Network

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

86

Rigidification of the autolysis loop enhances Na+ binding to thrombin  

E-print Network

Rigidification of the autolysis loop enhances Na+ binding to thrombin Nicola Pozzi, Raymond Chen April 2011 Keywords: Thrombin Na+ binding Allostery X-ray crystallography Binding of Na+ to thrombin+ with thrombin and possibly increase catalytic activity under physiological conditions have so far been

Di Cera, Enrico

87

Electrochemical Properties of Monoclinic NaNiO2  

E-print Network

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

Vassilaras, Plousia E.

88

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

89

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

PubMed Central

A single Na+/K+-ATPase pumps three Na+ outwards and two K+ inwards by alternately exposing ion-binding sites to opposite sides of the membrane in a conformational sequence coupled to pump autophosphorylation from ATP and auto-dephosphorylation. The larger flow of Na+ than K+ generates outward current across the cell membrane. Less well understood is the ability of Na+/K+ pumps to generate an inward current of protons. Originally noted in pumps deprived of external K+ and Na+ ions, as inward current at negative membrane potentials that becomes amplified when external pH is lowered, this proton current is generally viewed as an artifact of those unnatural conditions. We demonstrate here that this inward current also flows at physiological K+ and Na+ concentrations. We show that protons exploit ready reversibility of conformational changes associated with extracellular Na+ release from phosphorylated Na+/K+ pumps. Reversal of a subset of these transitions allows an extracellular proton to bind an acidic side chain and to be subsequently released to the cytoplasm. This back-step of phosphorylated Na+/K+ pumps that enables proton import is not required for completion of the 3 Na+/2 K+ transport cycle. However, the back-step occurs readily during Na+/K+ transport when external K+ ion binding and occlusion are delayed, and it occurs more frequently when lowered extracellular pH raises the probability of protonation of the externally accessible carboxylate side chain. The proton route passes through the Na+-selective binding site III and is distinct from the principal pathway traversed by the majority of transported Na+ and K+ ions that passes through binding site II. The inferred occurrence of Na+/K+ exchange and H+ import during the same conformational cycle of a single molecule identifies the Na+/K+ pump as a hybrid transporter. Whether Na+/K+ pumpmediated proton inflow may have any physiological or pathophysiological significance remains to be clarified. PMID:24688018

Vedovato, Natascia

2014-01-01

90

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

E-print Network

Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the lower Doppler lidars measure wind and temperature simultaneously in the meso- sphere and lower thermosphere [1-edge magneto-optic filter is proposed for incorporation into the receiver of a three-frequency Na Doppler lidar

Chu, Xinzhao

91

Determination of Na(2)O from sodium aluminate NaAlO(2).  

PubMed

The aim of the work was to find a suitable method and conditions for determining Na(2)O wt.% from NaAlO(2). Problems were encountered while titrating NaAlO(2) with hydrochloric acid. The problematic area was the pH range 4-10 where aluminum precipitates as hydroxides. The different species of the aluminate solution were determined using potentiometric and complexometric titrations. The equivalent point of the potentiometric titration was detected using Gran's plotting method. Precipitation of aluminum hydroxides did not interfere with titrations, because in potentiometric titrations the pH value was over 10 and in complexometric titrations the pH was 4. The results were accurate and determinations were easy to carry out. Sodium was also determined by DCP-AES. PMID:18968035

Nykki, T; Raimo, A; Paavo, P; Antero, K; Pivi, N

2000-07-31

92

Shank2 redistributes with NaPilla during regulated endocytosis  

PubMed Central

Serum phosphate levels are acutely impacted by the abundance of sodium-phosphate cotransporter IIa (NaPiIIa) in the apical membrane of renal proximal tubule cells. PSD-95/Disks Large/Zonula Occludens (PDZ) domain-containing proteins bind NaPiIIa and likely contribute to the delivery, retention, recovery, and trafficking of NaPiIIa. Shank2 is a distinctive PDZ domain protein that binds NaPiIIa. Its role in regulating NaPiIIa activity, distribution, and abundance is unknown. In the present in vivo study, rats were maintained on a low-phosphate diet, and then plasma phosphate levels were acutely elevated by high-phosphate feeding to induce the recovery, endocytosis, and degradation of NaPiIIa. Western blot analysis of renal cortical tissue from rats given high-phosphate feed showed NaPiIIa and Shank2 underwent degradation. Quantitative immunofluorescence analyses, including microvillar versus intracellular intensity ratios and intensity correlation quotients, showed that Shank2 redistributed with NaPiIIa during the time course of NaPiIIa endocytosis. Furthermore, NaPiIIa and Shank2 trafficked through distinct endosomal compartments (clathrin, early endosomes, lysosomes) with the same temporal pattern. These in vivo findings indicate that Shank2 is positioned to coordinate the regulated endocytic retrieval and downregulation of NaPiIIa in rat renal proximal tubule cells. PMID:20810910

Dobrinskikh, Evgenia; Giral, Hector; Caldas, Yupanqui A.; Levi, Moshe

2010-01-01

93

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

PubMed

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

Sato, Y; Yamada, T; Hasegawa, T

2014-05-01

94

O Teatro Brasileiro na Dcada de Oitenta  

E-print Network

Buenos Aires. O crepsculo da dcada de setenta e o raiar dos anos oitenta tambm testemunharam as primeiras edies e/ou encenaes de vrios tratamentos dramticos de um dos pilares da ditadura-a tortura. Milagre na cela, de Jorge Andrade, estreou... dcada de oitenta explica-se, ao menos em parte, pelas experincias dos que foram mais de perto atingidos pela censura da ditadura. Com a liberalizao poltica, Boal voltou ao Brasil pela primeira vez em oito anos para dar palestras e dirigir...

Albuquerque, Severino Joã o

1992-04-01

95

High [Na+]i in cardiomyocytes from rainbow trout.  

PubMed

Intracellular Na(+)-concentration, [Na(+)](i) modulates excitation-contraction coupling of cardiac myocytes via the Na(+)/Ca(2+) exchanger (NCX). In cardiomyocytes from rainbow trout (Oncorhyncus mykiss), whole cell patch-clamp studies have shown that Ca(2+) influx via reverse-mode NCX contributes significantly to contraction when [Na(+)](i) is 16 mM but not 10 mM. However, physiological [Na(+)](i) has never been measured. We recorded [Na(+)](i) using the fluorescent indicator sodium-binding benzofuran isophthalate in freshly isolated atrial and ventricular myocytes from rainbow trout. We examined [Na(+)](i) at rest and during increases in contraction frequency across three temperatures that span those trout experience in nature (7, 14, and 21 degrees C). Surprisingly, we found that [Na(+)](i) was not different between atrial and ventricular cells. Furthermore, acute temperature changes did not affect [Na(+)](i) in resting cells. Thus, we report a resting in vivo [Na(+)](i) of 13.4 mM for rainbow trout cardiomyocytes. [Na(+)](i) increased from rest with increases in contraction frequency by 3.2, 4.7, and 6.5% at 0.2, 0.5, and 0.8 Hz, respectively. This corresponds to an increase of 0.4, 0.6, and 0.9 mM at 0.2, 0.5, and 0.8 Hz, respectively. Acute temperature change did not significantly affect the contraction-induced increase in [Na(+)](i). Our results provide the first measurement of [Na(+)](i) in rainbow trout cardiomyocytes. This surprisingly high [Na(+)](i) is likely to result in physiologically significant Ca(2+) influx via reverse-mode NCX during excitation-contraction coupling. We calculate that this Ca(2+)-source will decrease with the action potential duration as temperature and contraction frequency increases. PMID:17507438

Birkedal, Rikke; Shiels, Holly A

2007-08-01

96

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

Microsoft Academic Search

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

L. O. Sillerud; J. W. Heyser

1984-01-01

97

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

2013-08-01

98

Neutron Multiplicity Discrimination in MoNA  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) is a high-efficiency neutron detector at the National Superconducting Cyclotron Laboratory at MSU, used in conjunction with the NSCL/FSU sweeper magnet to investigate the loss of one or more neutrons from particle-unbound nuclei near and beyond the neutron drip-line. In order to properly analyze data from these experiments it is important to distinguish neutron multiplicity in MoNA. We've developed an algorithm that produces scatter plots of neutron velocity change vs. scattering angle and energy deposition vs. scattering angle, each of which results in a locus of events corresponding (largely) to single neutron multiple-scatter events, and each of which can be used to gate the other for cross-correlation. Challenges to accurate neutron trajectory mapping include sub-threshold neutron scattering from carbon (which changes neutron trajectories in unpredictable ways) and the discrete nature of the array, which (especially for shorter scattering lengths) results in scattering angles not necessarily reflective of actual neutron trajectories. Results for experiments involving one and two neutron decays will be presented.

Rogers, W. F.; Gillette, J.; Gardner, M.; Reed, A.; Mosby, S.

2007-10-01

99

Luminescence of NaCl:Tl and NaCl:In at high pressure  

SciTech Connect

The effects of pressure up to 40 kbar and temperatures down to 100 /sup 0/K on the intensity and lifetime of NaCa:Tl/sup +/ and NaCl:In has been studied. A kinetic model describing these luminescent properties has been proposed. The /sup 3/T/sub lu/ level is in thermal equilibrium with /sup 3/A/sub lu/. Both /sup 3/T/sub lu/ and /sup 3/A/sub lu/ have nonradiative pathways to the ground state /sup 1/A/sub lg/. In addition /sup 3/T/sub lu/ is radiatively coupled to the ground state. Increasing pressure increases the radiative rate from /sup 3/T/sub lu/ to /sup 1/A/sub lg/ and has no effect on the equilibrium between /sup 3/T/sub lu/ and /sup 3/A/sub lu/. The back feeding rate from /sup 3/A/sub lu/ to /sup 3/T/sub lu/ is temperature sensitive for NaCl:Tl but not for NaCl:In.

Littman, J.E.; Drickamer, H.G.

1982-03-01

100

Theoretical calculation of low-lying states of NaAr and NaXe  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

101

Na-O Anticorrelation And HB I. The Na-O anticorrelation in NGC 2808  

E-print Network

We derived atmospheric parameters and elemental abundances of Fe, O and Na for about 120 red giant stars in the Galactic globular cluster NGC 2808. Our results are based on the analysis of medium-high resolution (R=22000-24000) GIRAFFE spectra acquired with the FLAMES spectrograph at VLT-UT2 as a part of a project aimed at studying the Na-O anticorrelation as a function of physical parameters in globular clusters. We present here the anticorrelation of Na and O abundances in NGC 2808, and we discuss the distribution function of stars along this relation. Besides a bulk of O-normal stars, with composition typical of field halo stars, NGC 2808 seems to host two other groups of O-poor and super O-poor stars. In this regard, NGC 2808 is similar to M 13, the template cluster for the Na-O anticorrelation. However, at variance with M 13, most stars in NGC 2808 are O-rich. This might be related to the horizontal branch morphologies which are very different in these two clusters. The average metallicity we found for NGC 2808 is [Fe/H]=-1.10 (rms=0.065 dex, from 123 stars). We also found some evidence of a small intrinsic spread in metallicity, but more definitive conclusions are hampered by the presence of a small differential reddening.

Eugenio Carretta; Angela Bragaglia; Raffaele Gratton; Francesco Leone; Alejandra Recio-Blanco; Sara Lucatello

2005-11-30

102

Na-O anticorrelation and HB. I. The Na-O anticorrelation in NGC 2808  

NASA Astrophysics Data System (ADS)

We derived the atmospheric parameters and elemental abundances of Fe, O, and Na for about 120 red giant stars in the Galactic globular cluster NGC 2808. Our results are based on the analysis of medium-high resolution (R=22 000{-}24 000) GIRAFFE spectra acquired with the FLAMES spectrograph at VLT-UT2 as a part of a project aimed at studying the Na-O anticorrelation as a function of physical parameters in globular clusters. We present the anticorrelation of Na and O abundances in NGC 2808 here, and discuss the distribution function of stars along this relation. Besides a bulk of O-normal stars with the typical composition of field halo stars, NGC 2808 seems to host two other groups of O-poor and super O-poor stars. In this regard, NGC 2808 is similar to M 13, the template cluster for the Na-O anticorrelation. However, in contrast to M 13, most stars in NGC 2808 are O-rich. This might be related to the horizontal branch morphologies that are very different in these two clusters. The average metallicity we found for NGC 2808 is [Fe/H]=-1.10 (rms = 0.065 dex, from 123 stars). We also found some evidence of a small intrinsic spread in metallicity, but more definitive conclusions are hampered by the presence of a small differential reddening.

Carretta, E.; Bragaglia, A.; Gratton, R. G.; Leone, F.; Recio-Blanco, A.; Lucatello, S.

2006-05-01

103

Minimizing Load Effects on NA4 Gear Vibration Diagnostic Parameter  

NASA Technical Reports Server (NTRS)

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

Dempsey, Paula J.; Zakrajsek, James J.

2001-01-01

104

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

105

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

PubMed

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

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

2014-08-01

106

Ionic Liquid Electrolytes with Various Sodium Solutes for Rechargeable Na/NaFePO4 Batteries Operated at Elevated Temperatures.  

PubMed

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

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

2014-10-22

107

Pyrophosphate-Fueled Na+ and H+ Transport in Prokaryotes  

PubMed Central

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

Malinen, Anssi M.; Luoto, Heidi H.

2013-01-01

108

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

PubMed Central

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

Despa, Sanda; Bers, Donald M.

2013-01-01

109

Cosmic Muon Tracking with MoNA  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) consists of 144 2-meter long scintillating bar detectors arranged in a structure 9 bars deep and 16 bars high. Each detector has a photo-multiplier tube attached at each end, allowing for position determination of events based on timing difference. The array is housed at the National Superconducting Cyclotron Laboratory at Michigan State University and will be used to study exotic nuclei near the neutron dripline. The array is tested and calibrated using cosmic muons, and an algorithm has been developed to extract high multiplicity muon events from the datastream to enable precise tracking for use in position calibration of the detectors. This method represents a superior calibration procedure since in addition to correcting for differential time response between the PMTs at the ends of each bar, it also accounts for any relative physical misalignment of the detectors in the array.

Watters, Kyle; Elliott, Lance; Strongman, Michael; Rogers, Warren

2004-10-01

110

Lakota na Dakota Wowapi Oti Kin  

NSDL National Science Digital Library

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

111

Function of FXYD Proteins, Regulators of Na, K-ATPase  

Microsoft Academic Search

In this short review, we summarize our work on the role of members of the FXYD protein family as tissue-specific modulators\\u000a of Na, K-ATPase. FXYD1 or phospholemman, mainly expressed in heart and skeletal muscle increases the apparent affinity for\\u000a intracellular Na+ of Na, K-ATPase and may thus be important for appropriate muscle contractility. FXYD2 or ? subunit and FXYD4 or

Kthi Geering

2005-01-01

112

Human myocardial Na,K-ATPase concentration in heart failure  

Microsoft Academic Search

The Na,K-ATPase is of major importance for active ion transport across the sarcolemma and thus for electrical as well as contractile function of the myocardium. Furthermore, it is receptor for digitalis glycosides. In human studies of the regulatory aspects of myocardial Na,K-ATPase concentration a major problem has been to obtain tissue samples. Methodological accomplishments in quantification of myocardial Na,K-ATPase using

Henning Bundgaard; Keld Kjeldsen

1996-01-01

113

Sodium superionic conduction in Na2B12H12.  

PubMed

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

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

2014-04-11

114

Magnesium correction to the NaKCa chemical geothermometer  

USGS Publications Warehouse

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

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

1979-01-01

115

Na+ interactions with the neutral amino acid transporter ASCT1.  

PubMed

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

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

2014-06-20

116

Kinetics of 9-aminoacridine block of single Na channels  

Microsoft Academic Search

The kinetics of 9-aminoacridine (9-AA) block of single Na chan- nels in neuroblastoma N 1 E-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

DAISUKE YAMAMOTO; JAY Z. YEH

1984-01-01

117

CaMKII-dependent regulation of cardiac Na+ homeostasis  

PubMed Central

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

Grandi, Eleonora; Herren, Anthony W.

2014-01-01

118

Mercury's Na Exosphere from MESSENGER Data  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

119

Questes mais freqentes na rea de astronomia  

NASA Astrophysics Data System (ADS)

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

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

2003-08-01

120

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 80C 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

121

Reconstitution of a bacterial Na+/H+ antiporter  

SciTech Connect

Membrane proteins from alkalophilic Bacillus firmus RAB were extracted with octylglucoside, reconstituted into liposomes made from alkalophile lipids. The proteoliposomes were loaded with SSNa . Imposition of a valinomycin-mediated potassium diffusion potential, positive out, resulted in very rapid efflux of radioactive Na against its electrochemical gradient. That the Na efflux was mediated by the electrogenic Na /H antiporter is indicated by the following characteristics that had been established for the porter in previous studies: dependence upon an electrical potential; pH sensitivity, with activity dependent upon an alkaline pH; inhibition by Li ; and an apparent concentration dependence upon Na that correlated well with measurements in cells and membrane vesicles.

Seto-Young, D.; Garcia, M.L.; Krulwich, T.A.

1985-09-25

122

Association reactions of Na(+) and some implications for interstellar chemistry  

NASA Astrophysics Data System (ADS)

Three-body association reactions of Na+ with a variety of neutral gases in the presence of He as third body have been studied in a Selected Ion Flow Tube at 80K. The measured rate coefficients have been utilized to estimate radiative association rate coefficients at 20K. It is shown that Na+-neutral radiative association reactions play a role in the depletion of Na+ in dense interstellar clouds and can produce a sufficient amount of NaOH to explain its observed tentative abundance in Sgr B2.

Smith, D.; Adams, N. G.; Alge, E.; Herbst, E.

1983-09-01

123

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

PubMed

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

Sillerud, L O; Heyser, J W

1984-05-01

124

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

SciTech Connect

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

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

1984-05-01

125

Electrode potential studies of liquid-solid equilibrium in Na{sub 3}Bi-saturated Na-Bi melts  

SciTech Connect

Liquid binary Na-Bi alloys have been studied extensively because of the interest in possible uses as electrochemically active couples in regenerative electrochemical cells, in high-energy batteries, and as potential heat-transfer media in nuclear reaction processes. Techniques used previously for thermodynamic measurements on the system have included the transpiration method, quasi-static and boiling point methods, the electromotive force (emf) method using molten salt mixtures and various solid electrolytes, and thermal analysis. Most of the thermodynamic data on Bi-Na alloys were recently assessed by Sangster and Pelton. However, no experimental thermodynamic data for liquid-solid equilibrium in liquid Na-Bi alloys saturated with solid Na{sub 3}Bi have been reported in the literature. The aim of the present work was to investigate experimentally the equilibrium between Na-Bi melts and solid Na{sub 3}Bi by the emf method in the range 638 to 973 K.

Yan, X.Y.; Langberg, D.E.; Rankin, W.J.

2000-04-01

126

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

PubMed Central

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

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

2014-01-01

127

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

128

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

NASA Astrophysics Data System (ADS)

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

Nafisi, Shohreh; Manouchehri, Firouzeh; Montazeri, Maryam

2011-12-01

129

Conductance and gating of epithelial Na channels from rat cortical collecting tubule. Effects of luminal Na and Li  

Microsoft Academic Search

The behavior of individual Na channels in the apical membrane of the rat cortical collecting tubule (CCT) was studied at different concentrations of the permeant ions Na and Li. Tubules were opened to expose their luminal sur- faces and bathed in K-gluconate medium to minimize tubule-to-tubule variation in cell membrane potential and intracellular Na concentration. The patch-clamp technique was used

LAWRENCE G. PALMER; GUSTAVO FRINDT

1988-01-01

130

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

E-print Network

/informativos/os-universitarios-da-coruna-comparten-unha-xornada-de- gastronomia-solar-573783 http://www.lavozdegalicia.es/noticia/coruna/2013/04/24/cocina-universitaria-energiaCr�nica I Encontro Solar na UDC O pasado m�rcores 24 de abril tivo lugar na Praza da Fraga (Campus da Zapateira) a primeira edici�n do Encontro Solar na UDC. Esta era a terceira das actividades

Fraguela, Basilio B.

131

Solubility of MgO in MgCl{sub 2}-NaCl-NaF melts  

SciTech Connect

The solubility of MgO in MgCl{sub 2}-NaCl-NaF melts has been measured for melts with varying NaF concentration for x{sub MgCl{sub 2}} = 0.10 and 0.63 and for x{sub MgCl{sub 2}}/x{sub NaCl} = 1.70. Melt samples have been analyzed by carbothermal reduction (Leco TC-436) for total oxide content. The oxide content in the binary melt MgCl{sub 2}-NaCl was also analyzed by Iodometric titration. The results indicate two different oxide-containing species, denoted MgOCl and MgOF, in the solidified samples withdrawn from the melt. The latter appears only in fluoride-containing melts, but may, however, also contain chloride ions. The oxide solubility is increasing with increasing concentration of Mg{sup 2+} in both MgCl{sub 2}-NaCl and MgCl{sub 2}-NaCl-NaF melts. The solubility of MgO is always higher in fluoride containing melts at the same Mg{sup 2+} concentration. In the systems concentrated in MgCl{sub 2}, the increase in oxide solubility as function of x{sub NaF} is more pronounced than what is predicted from a simple model calculation. The increase is much smaller in the x{sub NaF} < 0.2 range for small MgCl{sub 2} contents than predicted from the same model calculation. The introduction of 1.7 mol% NaF to an industrial electrolyte does not seem to change the oxide solubility significantly. In such an electrolyte, where x{sub MgCl{sub 2}} {approx_equal} 0.1, the data gives a constant oxide solubility around 10 ppm O up to 5 mol% NaF.

Mediaas, H.; Vinstad, J.E.; Oestvold, T. [Norwegian Inst. of Tech., Trondheim (Norway). Inst. of Inorganic Chemistry

1996-10-01

132

Propagac ~ao acustica em aguas profundas na presenca de massas d'aguas de mesoescala na costa sudoeste de Portugal  

E-print Network

Propagac¸ ~ao ac´ustica em ´aguas profundas na presenc¸a de massas d'´aguas de mesoescala na costa trabalho baseia-se no estudo da propagac¸ ~ao sonora em ´aguas oce^anicas profundas na costa Portuguesa massa d'´agua de mesosescala. Mostraremos que tal massa d'´agua d´a origem `a um acoplamento entre dois

Jesus, Sérgio M.

133

EDITORIAL: TaCoNa-Photonics 2008 TaCoNa-Photonics 2008  

Microsoft Academic Search

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

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

2009-01-01

134

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

PubMed

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

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

2014-12-01

135

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

136

Cryptography in NaCl Daniel J. Bernstein  

E-print Network

Cryptography in NaCl Daniel J. Bernstein Department of Computer Science (MC 152) The University against espionage and sabotage. Programmers can use lower-level functions but are encouraged to use crypto is expressed as a step-by-step procedure for Alice to encrypt and authenticate a packet; NaCl might compute

Bernstein, Daniel

137

Branching ratios for the beta decay of Na-21  

E-print Network

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

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

2006-01-01

138

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

E-print Network

Thyroid Na /I Symporter MECHANISM, STOICHIOMETRY, AND SPECIFICITY* (Received for publication, May College of Medicine, Bronx, New York 10461 The rat thyroid Na /I symporter (NIS) was expressed in Xenopus. It is now firmly established that active accumulation of io- dide (I ) by the thyroid gland epithelium

Eskandari, Sepehr

139

Adaptation of Tobacco Cells to NaCl 1  

PubMed Central

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

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

1985-01-01

140

Hydrothermal Synthesis of (K,Na)NbO3 Particles  

NASA Astrophysics Data System (ADS)

(K,Na)NbO3 (KNN) particles were successfully prepared by hydrothermal synthesis. The results showed that Na+ reacted more readily with Nb to form NaNbO3 than K+. For the purpose of obtaining KNN particles with K/Na=1, a mixed alkaline solution with K+/Na+ ratios ranging from 3.5/1 to 4/1 was required as a starting solution. The morphology and size of KNN particles synthesized strongly depended on K/Na ratio in the KNN particles. The KNN particles synthesized from the starting alkaline solution with K+/Na+=3.5/1 were the smallest with a pelletlike morphology affected by NaNbO3- and KNbO3-based particles. Surfactants such as sodium dodecylbenzenesulfonate (SDBS) and sodium hexametaphosphate (SH) were used to synthesize well dispersed and small KNN particles. Platelike KNN particles with 100 nm thickness and 1.5 m width were obtained in this study.

Zhang, Fan; Han, Lu; Bai, Shan; Sun, Tiedong; Karaki, Tomoaki; Adachi, Masatoshi

2008-09-01

141

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

NASA Astrophysics Data System (ADS)

The present paper gives an account of investigations of the polarizability of the alkali atoms Li, Na, diatomics homonuclear and heteronuclear Li2, Na2 and NaLi at SCF (Self Consistent Field) level of approximation and at correlated level, using a time Time-Dependent Gauge Invariant method (TDGI). Our static polarizability values agree with the best experimental and theoretical determinations. The Van der Waals C6 coefficients for the atom-atom, atom-dimer and dimer-dimer interactions have been evaluated. Les polarisabilits des atomes alcalins Li, Na, et des molcules diatomiques homonuclaires et htronuclaire Li2, Na2 et NaLi, ont t calcules au niveau SCF (Self Consistent Field) et au niveau corrl partir d'une mthode invariante de jauge dpendante du temps(TDGI). Nos valeurs des polarisabilits statiques sont en accord avec les meilleurs dterminations exprimentales et thoriques. Les coefficients C6 de Van de Waals pour les interactions atome-atome, atome-dimre et dimre-dimre ont galement t valus.

Mrawa, M.; Dargelos, A.

1998-07-01

142

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

PubMed

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

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

2013-12-20

143

[Catalytic properties of solubilized brain Na+,K+-ATPase].  

PubMed

The results are presented of a kinetic study of solubilized Na+, K+-ATPase obtained by 0.2+ digitonin from the NaI treated microsome fraction of the bull brain. It is shown that in main kinetic parameters (KmATP, V, pH-optimum, optimal [Na+]/[K+] ratio, etc.) the solubilized Na+, K+-ATPase does not differ essentially from membrane-bound enzyme. These results evidence for the absence of changes in principle for the kinetic behaviour of Na+,K+-ATPase when solubilized with digitonin. Simultaneously there are certain differences for a temperature dependence (the bend position in the Arrhenius anamorphosis) of the solubilized enzyme and its sensitivity to the action of strophanthin K. PMID:219575

Kravtsov, A V

1978-01-01

144

Dissociation of Methane Hydrate in Aqueous NaCl Solutions.  

PubMed

Molecular dynamics simulations of the dissociation of methane hydrate in aqueous NaCl solutions are performed. It is shown that the dissociation of the hydrate is accelerated by the formation of methane bubbles both in NaCl solutions and in pure water. We find two significant effects on the kinetics of the hydrate dissociation by NaCl. One is slowing down in an early stage before bubble formation, and another is swift bubble formation that enhances the dissociation. These effects arise from the low solubility of methane in NaCl solution, which gives rise to a nonuniform spatial distribution of solvated methane in the aqueous phase. We also demonstrate that bubbles form near the hydrate interface in dense NaCl solutions and that the hydrate dissociation proceeds inhomogeneously due to the bubbles. PMID:25237735

Yagasaki, Takuma; Matsumoto, Masakazu; Andoh, Yoshimichi; Okazaki, Susumu; Tanaka, Hideki

2014-10-01

145

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

146

NA60 results on thermal dimuons  

NASA Astrophysics Data System (ADS)

The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In-In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2< M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from ? + ? -? ?? ? + ? - annihilation. The associated ? spectral function shows a strong broadening, but essentially no shift in mass. For M>1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell-Yan pairs. The slope parameter T eff associated with the transverse momentum spectra rises with mass up to the ?, followed by a sudden decline above. The rise for M<1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M>1 GeV and its relation to parton-hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Planck-like shape of the mass spectra at low p T and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on ? in-medium effects.

Arnaldi, R.; Banicz, K.; Borer, K.; Castor, J.; Chaurand, B.; Chen, W.; Cical, C.; Colla, A.; Cortese, P.; Damjanovic, S.; David, A.; de Falco, A.; Devaux, A.; Ducroux, L.; En'yo, H.; Fargeix, J.; Ferretti, A.; Floris, M.; Frster, A.; Force, P.; Guettet, N.; Guichard, A.; Gulkanian, H.; Heuser, J. M.; Keil, M.; Kluberg, L.; Li, Z.; Loureno, C.; Lozano, J.; Manso, F.; Martins, P.; Masoni, A.; Neves, A.; Ohnishi, H.; Oppedisano, C.; Parracho, P.; Pillot, P.; Poghosyan, T.; Puddu, G.; Radermacher, E.; Ramalhete, P.; Rosinsky, P.; Scomparin, E.; Seixas, J.; Serci, S.; Shahoyan, R.; Sonderegger, P.; Specht, H. J.; Tieulent, R.; Usai, G.; Veenhof, R.; Whri, H. K.

2009-06-01

147

Electrochemical Migration Characteristics of Eutectic Sn-Pb Solder Alloy in NaCl and Na2SO4 Solutions  

NASA Astrophysics Data System (ADS)

Anodic dissolution and the electrochemical migration characteristics of eutectic Sn-Pb solder alloy in deaerated 0.001% NaCl and Na2SO4 solutions were investigated using anodic polarization and water drop tests. Anodic polarization results revealed that a Pb-rich phase was preferentially ionized in deaerated 0.001% NaCl solution and an Sn-rich phase was predominantly ionized in deaerated 0.001% Na2SO4 solution, which coincides well with the composition of the dendrites formed during water drop tests. X-ray diffraction and photoelectron spectroscopy results showed that the surface oxide film formed on pure Sn in deaerated 0.001% NaCl solution is more stable than that formed on pure Sn in deaerated 0.001% Na2SO4 solution. The surface oxide film formed on pure Pb in deaerated 0.001% Na2SO4 solution is more stable than that formed on pure Sn in deaerated 0.001% NaCl solution. Therefore, the quality of the surface film of eutectic Sn-Pb solder in a chemical environment seems to be critical not only for corrosion resistance, but also for electrochemical migration resistance.

Jung, Ja-Young; Lee, Shin-Bok; Lee, Ho-Young; Joo, Young-Chang; Park, Young-Bae

2009-05-01

148

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

149

Regulation of Cardiac Ca2+ Channel by Extracellular Na+  

PubMed Central

Hyponatremia is a predictor of poor cardiovascular outcomes during acute myocardial infarction and in the setting of preexisting heart failure [1]. There are no definitive mechanisms as to how hyponatremia suppresses cardiac function. In this report we provide evidence for direct down-regulation of Ca2+ channel current in response to low serum Na+. In voltage-clamped rat ventricular myocytes or HEK 293 cells expressing the L-type Ca2+ channel, a 15 mM drop in extracellular Na+ suppressed the Ca2+ current by ~15%; with maximal suppression of ~30% when Na+ levels were reduced to 100 mM or less. The suppressive effects of low Na+ on ICa, in part, depended on the substituting monovalent species (Li+, Cs+, TEA+), but were independent of phosphorylation state of the channel and possible influx of Ca2+ on Na+/Ca2+ exchanger. Acidification sensitized the Ca2+ channel current to Na+ withdrawal. Collectively our data suggest that Na+ and H+ may interact with regulatory site(s) at the outer recesses of the Ca2+ channel pore thereby directly modulating the electro-diffusion of the permeating divalents (Ca2+, Ba2+). PMID:21349579

Movafagh, Shahrzad; Cleemann, Lars; Morad, Martin

2011-01-01

150

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. PMID:21536369

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

2011-01-01

151

Two-frequency lidar technique for mesospheric Na temperature measurements  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

152

Slovenski terminoloki sistemi na primeru pravne terminologije  

E-print Network

motivirajo- ?ega pomena omogo?a natan?nost in nedvoumnost motiviranega. 4 Pogodba o Ustavi za Evropo (PUE) Za pravni red ES (acquis communautaire) 1#4; velja na?elo primarnosti, kar pomeni, da pravna pravila, sprejeta na ravni EU, prevladajo nad pravnimi... tudi PUE postala del pri- marne zakonodaje. Njena priprava je bila napovedana v Izjavi o prihodnosti Unije (Laeken, decem- ber 2001), ki je bila dodana Pogodbi iz Nice. 1#4; V skladu z Laekensko izjavo se je o prihodnosti EU odlo?alo na Konvenciji o...

Fajfar, Tanja

2007-01-01

153

Ion Program of Na61/Shine at the CERN SPS  

E-print Network

The NA61/SHINE experiment at the CERN SPS aims to discover the critical point of strongly interacting matter and study properties of the onset of deconfinement. These goals will be reached by measurements of hadron production properties in nucleus-nucleus, proton-proton and proton-lead interactions as a function of collision energy and size of the colliding nuclei. Furthermore, NA61/SHINE will perform numerous precision measurements needed for neutrino (T2K) and cosmic-ray (Pierre Auger Observatory and KASCADE) experiments. This paper summarizes physics arguments for the NA61/SHINE ion program and presents the status and plans of the experiment.

M. Gazdzicki; for the NA61/SHINE Collaboration

2008-12-23

154

Dianion formation from anion-alkali metal charge exchange reactions: TCNQ^- + Na -> TCNQ^-- + Na^+  

NASA Astrophysics Data System (ADS)

The interaction of an electron with an anion is characterized by a long-range coulomb repulsion and a short range polarizability attraction giving rise to a coulomb barrier. The permanent addition of an extra electron to a negatively charged anion requires tunneling through the barrier or attachment of the electron over the top of this coulomb barrier followed by disposal of the excess energy. Charge-exchange collisions of an anion with an alkali atom utilize the latter channel to produce permanent dianions with cross sections of 1 ^2. We have previously examined the reaction TCNQ-F4^- + Xe -> TCNQ-F4^-- + Xe^+ and reported a delayed threshold and quantum phase interference effects in the charge exchange cross section.ootnotetextS. Yu. Ovchinnikov, et al. Phys. Rev. A, 73, 64704(2006) Employing sodium as the collision partner, the cross section is seen to increase with decreasing energy with a threshold below 180 eV (com). A new apparatus has been constructed to allow measurements down to energies below the expected threshold (41 eV, laboratory energy based upon a 1 eV second electron affinity). This method has been used to study the reaction TCNQ^- + NA -> TCNQ^-- + Na^+ and will provide one of the first measurements of second electron affinities for molecular anions.

Smith, Byron; Compton, Robert; Ovchinnikov, Serge; Holm, Anne; Nielsen, Steen

2011-10-01

155

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

PubMed Central

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

Billen, Bert; Debaveye, Sarah; Beress, Laszlo; Tytgat, Jan

2010-01-01

156

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

157

Determinants of substrate and cation transport in the human Na+/dicarboxylate cotransporter NaDC3.  

PubMed

Metabolic intermediates, such as succinate and citrate, regulate important processes ranging from energy metabolism to fatty acid synthesis. Cytosolic concentrations of these metabolites are controlled, in part, by members of the SLC13 gene family. The molecular mechanism underlying Na(+)-coupled di- and tricarboxylate transport by this family is understood poorly. The human Na(+)/dicarboxylate cotransporter NaDC3 (SLC13A3) is found in various tissues, including the kidney, liver, and brain. In addition to citric acid cycle intermediates such as ?-ketoglutarate and succinate, NaDC3 transports other compounds into cells, including N-acetyl aspartate, mercaptosuccinate, and glutathione, in keeping with its dual roles in cell nutrition and detoxification. In this study, we construct a homology structural model of NaDC3 on the basis of the structure of the Vibrio cholerae homolog vcINDY. Our computations are followed by experimental testing of the predicted NaDC3 structure and mode of interaction with various substrates. The results of this study show that the substrate and cation binding domains of NaDC3 are composed of residues in the opposing hairpin loops and unwound portions of adjacent helices. Furthermore, these results provide a possible explanation for the differential substrate specificity among dicarboxylate transporters that underpin their diverse biological roles in metabolism and detoxification. The structural model of NaDC3 provides a framework for understanding substrate selectivity and the Na(+)-coupled anion transport mechanism by the human SLC13 family and other key solute carrier transporters. PMID:24808185

Schlessinger, Avner; Sun, Nina N; Colas, Claire; Pajor, Ana M

2014-06-13

158

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

NASA Astrophysics Data System (ADS)

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

Smirnov, A. D.

2014-09-01

159

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

PubMed

A Na double-edge magneto-optic filter is proposed for incorporation into the receiver of a three-frequency Na Doppler lidar to extend its wind and temperature measurements into the lower atmosphere. Two prototypes based on cold- and hot-cell designs were constructed and tested with laser scanning and quantum mechanics modeling. The hot-cell filter exhibits superior performances over the cold-cell filter containing buffer gas. Lidar simulations, metrics, and error analyses show that simultaneous wind and temperature measurements are feasible in the altitude range of 20-50 km using the hot-cell filter and reasonable Na lidar parameters. PMID:19148254

Huang, Wentao; Chu, Xinzhao; Williams, B P; Harrell, S D; Wiig, Johannes; She, C-Y

2009-01-15

160

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

E-print Network

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

MacLean, B T; Lattanzio, J

2014-01-01

161

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

162

Na decorated B6 cluster and its hydrogen storage properties  

NASA Astrophysics Data System (ADS)

The structures and hydrogen storage properties of sodium atoms decorated B6 clusters are investigated by the B3LYP method with a 6-311+G (d, p) basis set. For NamB6 (m = 1-3) clusters, Na atoms are always inclined to separate far enough from each other and not cluster together on a B6 cluster surface so that each Na atom has sufficient space to bind hydrogen molecules. The hydrogen storage gravimetric density of a two Na atoms decorated B6 cluster is 17.91 wt% with an adsorption energy per H2 molecule (AAE/H2) of 0.6851 kcalmol-1. The appropriate AAE/H2 and preferable gravimetric density of the two Na atoms decorated B6 cluster complex indicate that it is feasible for hydrogen storage application in ambient conditions.

Ruan, Wen; Wu, Dong-Lan; Luo, Wen-Lang; Yu, Xiao-Guang; Xie, An-Dong

2014-02-01

163

Regulation of Na v channels in sensory neurons.  

PubMed

Voltage-gated Na(+) channels have an essential role in the biophysical properties of nociceptive neurons. Factors that regulate Na(+) channel function are of interest from both pathophysiological and therapeutic perspectives. Increasing evidence indicates that changes in expression or inappropriate modulation of these channels leads to electrical instability of the cell membrane and the inappropriate spontaneous activity that is observed following nerve injury, and that this might contribute to neuropathic pain. The role of Na(v) channels in nociception depends on modulation by factors such as auxiliary beta-subunits, cytoskeletal proteins and the phosphorylation state of neurons. In this review we describe the modulation of Na(v) channels on sensory neurons by auxiliary beta-subunits, protein kinases and cytoskeletal proteins. PMID:16125256

Chahine, Mohamed; Ziane, Rahima; Vijayaragavan, Kausalia; Okamura, Yasushi

2005-10-01

164

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 Grdes (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 lk

2004-01-01

165

1674 -XIV Encuentro de Latinoamericanistas Espaoles DITADURA MILITAR NA  

E-print Network

1674 - XIV Encuentro de Latinoamericanistas Españoles DITADURA MILITAR NA AM?RICA LATINA E O, significativas decisões sobre o legado autoritário das ditaduras militares na América Latina das décadas de 1970 transição. No entanto, no Brasil, não só não houve responsabilização pelos crimes da ditadura, como há uma

Paris-Sud XI, Université de

166

Measurement of Na +,K +ATPase Activity in Human Skeletal Muscle  

Microsoft Academic Search

There are few published measures of Na+,K+-ATPase activity in human skeletal muscle. This study investigated the suitability of the K+-stimulated 3-O-methylfluorescein phosphatase assay for measurement of Na+,K+-ATPase activity in human skeletal muscle. Factors investigated include enzyme kinetics, sample treatment, and ligand concentration. The addition of ouabain blocked maximal K+-stimulated 3-O-methylfluorescein phosphatase (3-O-MFPase) activity, confirming the specificity of the assay. Activity

Steve F. Fraser; Michael J. McKenna

1998-01-01

167

Vanadate stimulates the pumped movements of Na in skeletal muscle  

Microsoft Academic Search

We have measured the effects of concentrations of vanadate ranging between 0.01 and 10 mM on the22Na efflux of frog sartorius muscles. The addition of vanadate had no effects when concentrations lower than 0.5 mM were used; higher concentrations increased Na efflux. The increase was abolished by the addition of ouabain (10-5M). In muscles pretreated with ouabain vanadate did not

David Erlij

1984-01-01

168

In vivo modification of Na +,K +ATPase activity in Drosophila  

Microsoft Academic Search

We have constructed and characterized transgenic Drosophila lines with modified Na+,K+-ATPase activity. Using a temperature dependent promoter from the hsp70 gene to drive expression of wild-type ? subunit cDNA, we can conditionally rescue bang-sensitive paralysis and ouabain sensitivity of a Drosophila Na+,K+-ATPase ? subunit hypomorphic mutant, 2206. In contrast, a mutant ? subunit (?D369N) leads to increased bang-sensitive paralysis and

Banghua Sun; Peizhang Xu; Weiya Wang; Paul M. Salvaterra

2001-01-01

169

g State of Na2: Vibrational Numbering and Hyperfine Structure  

E-print Network

The 43 g State of Na2: Vibrational Numbering and Hyperfine Structure G. Lazarov,* A. M. Lyyra,*,1 The Na2 43 g state has been studied by continuous-wave (cw) perturbation-facilitated optical of the 43 g (v, N) 4 b3 u (vb, J ) A1 u (vA, J ) 4 X1 g (v , J ) transitions show hyperfine splittings

Huennekens, John

170

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 E22K+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. PMID:21708939

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

2011-01-01

171

Stabilization of Na,KATPase by ionic interactions  

Microsoft Academic Search

The effect of ions on the thermostability and unfolding of Na,KATPase from shark salt gland was studied and compared with that of Na,KATPase from pig kidney by using differential scanning calorimetry (DSC) and activity assays. In 1mM histidine at pH 7, the shark enzyme inactivates rapidly at 20C, as does the kidney enzyme at 42C (but not at 20C). Increasing

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

2008-01-01

172

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

173

The thermopower of liquid Na-Sn alloys  

Microsoft Academic Search

The thermopower, Q, of liquid Na-Sn alloys has been measured as a function of temperature and composition. This alloys system shows a non-NFE behaviour in large parts of the composition range. For dilute Na-Sn alloys, it is shown that the measurements are consistent with a very simple phase-shift calculation. For concentrated alloys, a theoretical interpretation is complicated by the existence

J. A. Meijer; W. van der Lugt

1991-01-01

174

Effect of dronedarone on Na + , Ca 2+ and HCN channels  

Microsoft Academic Search

Previous studies showed that amiodarone causes state-dependent inhibition of Na+ channels thereby mediating an atrial-selective drug effect. The aim of the present study was to investigate the impact of\\u000a the new antiarrhythmic compound dronedarone on Na+, Ca2+ and hyperpolarization-activated cyclic nucleotide-gated ion channels. Monophasic action potentials (MAP) and effective refractory\\u000a period (ERP) were studied in arterially perfused left atria and

Roman Bogdan; Heinz Goegelein; Hartmut Ruetten

2011-01-01

175

A stable Na + \\/H + antiporter of thermophilic bacterium PS3  

Microsoft Academic Search

As a first step in the isolation of a stable Na+\\/H+ antiporter, its reaction in sonicated membrane vesicles of thermophilic bacterium PS3 has been characterized. The sonicated vesicles showed quenching of quinacrine fluorescence in either NADH oxidation or ATP hydrolysis. The quenching was reversed by the addition of Na+, Li+, Mn2+, Cd2+, and Co2+, but not of choline+ or Ca2+,

Kimihiko Goto I; Hajime Hirata; Yasuo Kagawa

1980-01-01

176

Reactions of NaCl with Gaseous SO3, SO2, and O2  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

177

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

PubMed

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

Tan, Hui Lin; McGrath, Kathryn M

2012-09-01

178

Band gap engineering for graphene by using Na+ ions  

NASA Astrophysics Data System (ADS)

Despite the noble electronic properties of graphene, its industrial application has been hindered mainly by the absence of a stable means of producing a band gap at the Dirac point (DP). We report a new route to open a band gap (Eg) at DP in a controlled way by depositing positively charged Na+ ions on single layer graphene formed on 6H-SiC(0001) surface. The doping of low energy Na+ ions is found to deplete the ?* band of graphene above the DP, and simultaneously shift the DP downward away from Fermi energy indicating the opening of Eg. The band gap increases with increasing Na+ coverage with a maximum E g ? 0.70 eV. Our core-level data, C 1s, Na 2p, and Si 2p, consistently suggest that Na+ ions do not intercalate through graphene, but produce a significant charge asymmetry among the carbon atoms of graphene to cause the opening of a band gap. We thus provide a reliable way of producing and tuning the band gap of graphene by using Na+ ions, which may play a vital role in utilizing graphene in future nano-electronic devices.

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

2014-08-01

179

MoNA and initial measurements with 7He Resonance *  

NASA Astrophysics Data System (ADS)

Of recent interest in the study of exotic nuclei are neutron rich nuclei near and beyond the drip line. Using radioactive beams produced at the National Superconducting Cyclotron Laboratory (NSCL), the Modular Neutron Array (MoNA) detector, and a 4 Tesla sweeper magnet it is possible to study these nuclei. MoNA is a large area, high-efficiency neutron detector consisting of 144 plastic scintillating bars. When used in tandem with the series of detectors and scintillators in the sweeper setup MoNA is capable of detecting neutrons in coincidence with reaction fragments detected at the sweeper. As an initial experiment to test the tandem setup of MoNA and the sweeper a secondary beam of 8Li was produced in the coupled cyclotron facility and the reaction of interest, stripping off a proton to observe the resonance of 7He immediately decaying to 6He+n, was studied with MoNA and the sweeper. The ground state of 7He resonance was observed in the relative velocities of 6He and the neutron. *MoNA collaboration is supported by the NSF. TP, RP acknowledge the support from the NSF Research Experience for Undergraduates program.

Pike, Tina; Pepin, Robert

2004-10-01

180

Clusters of axonal Na+ channels adjacent to remyelinating Schwann cells.  

PubMed

Rat sciatic nerve fibres were demyelinated by injection of lysolecithin and examined at several stages as Schwann cells proliferated, adhered, and initiated remyelination. Immunoperoxidase EM has been used to follow the clustering of Na+ channels that represents an early step in the formation of new nodes of Ranvier. At the peak of demyelination, 1 week post-injection, only isolated sites, suggestive of the original nodes, were labelled. As Schwann cells adhered and extended processes along the axons, regions of axonal Na+ channel immunoreactivity were often found just beyond their leading edges. These channel aggregates were associated only with the axolemma and Na+ channels were not detected on glial membranes. Sites with more than one cluster in close proximity and broadly labelled aggregates between Schwann cells suggested that new nodes of Ranvier formed as neighbouring Na+ channel groups merged. Schwann cells thus seem to play a major role in ion channel distributions in the axolemma. In all of these stages Na+ channel label was found primarily just outside the region of close contact between axon and Schwann cell. This suggests that Schwann cell adherence acts in part to exclude Na+ channels, or that diffusible substances are involved and can act some distance from regions of direct contact. PMID:8835788

Novakovic, S D; Deerinck, T J; Levinson, S R; Shrager, P; Ellisman, M H

1996-06-01

181

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 , 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

182

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

Microsoft Academic Search

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

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

1994-01-01

183

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

PubMed Central

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

Babes, A; Fendler, K

2000-01-01

184

Na/Ca Exchange and Na/K-ATPase Function Are Equally Concentrated in Transverse Tubules of Rat Ventricular Myocytes  

PubMed Central

Formamide-induced detubulation of rat ventricular myocytes was used to investigate the functional distribution of the Na/Ca exchanger (NCX) and Na/K-ATPase between the t-tubules and external sarcolemma. Detubulation resulted in a 32% decrease in cell capacitance, whereas cell volume was unchanged. Thus, the surface-to-volume ratio was used to assess the success of detubulation. NCX current (INCX) and Na/K pump current (Ipump) were recorded using whole-cell patch clamp, as Cd-sensitive and K-activated currents, respectively. Both inward and outward INCX density was significantly reduced by ?40% in detubulated cells. INCX density at 0 mV decreased from 0.19 0.03 to 0.10 0.03 pA/pF upon detubulation. Ipump density was also lower in detubulated myocytes over the range of voltages (?50 to +100 mV) and internal [Na] ([Na]i) investigated (722 mM). At [Na]i = 10 mM and ?20 mV, Ipump density was reduced by 39% in detubulated myocytes (0.28 0.02 vs. 0.17 0.03 pA/pF), but the apparent Km for [Na]i was unchanged (16.9 0.4 vs. 17.0 0.3 mM). These results indicate that although thet-tubules represent only ?32% of the total sarcolemma, they contribute ?60% to the total INCX and Ipump. Thus, the functional density of NCX and Na/K pump in the t-tubules is 33.5-fold higher than in the external sarcolemma. PMID:14581240

Despa, S.; Brette, F.; Orchard, C. H.; Bers, D. M.

2003-01-01

185

Early Age Strength and Workability of Slag Pastes Activated by NaOH and Na 2CO 3  

Microsoft Academic Search

This paper reports the results of an investigation on activation of blast furnace slag with the emphasis on achievement of equivalent one-day strength to Portland cement at normal curing temperatures and reasonable workability. The effects of varying dosages of activators NaOH and Na2CO3 are discussed in terms of strength of mini cylinders and also workability by the mini slump method.

F. Collins; J. G. Sanjayan

1998-01-01

186

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 qualityspecific thresholds that are likely to represent differences in peripheral taste responsiveness. The strain differences in NaCl taste sensitivity found in this study provide a basis for genetic analysis of this phenotype. PMID:22293936

Ishiwatari, Yutaka

2012-01-01

187

A kinetic analysis of Na-Li countertransport in human red blood cells  

PubMed Central

We examined the kinetic properties of the interactions between inner and outer cation sites of the Na-Li countertransport system in human red blood cells. Li-stimulated Na efflux [V(Na)] was measured as a function of external Li [(Li)o] and internal Na [(Na)i] contents. At each (Li)o, a Hanes plot of (Na)i/V(Na) vs. (Na)i allowed us to calculate the apparent dissociation constant for internal Na (KiNa) and the maximal rate of Na efflux [Vmax(Na)]. In erythrocytes from 10 different subjects, the Vmax(Na)/KiNa ratios were independent of the external Li concentrations. In other experiments, Na-stimulated Li efflux [V(Li)] was measured as a function of external Na and internal Li contents. In three subjects studied, the Vmax(Li)/KiLi ratios were independent of the external Na concentrations. The data strongly suggest that the countertransport mechanism is consecutive ("ping- pong"). PMID:2420916

1986-01-01

188

Requirement of the Na+/H+ exchanger for tumor growth.  

PubMed

The Na+/H+ exchanger is involved in a variety of cellular processes, including regulation of intracellular pH and possibly the control of cell growth and proliferation. To study the role of the Na+/H+ exchanger in tumor growth, human sodium proton exchanger-deficient (HSPD) mutants were derived from the human bladder carcinoma cell line MGH-U1 (EJ) by the proton suicide selection technique (J. Pouyssegur et al., Proc. Natl. Acad. Sci. USA, 81: 4833-4837, 1984). The HSPD cells were approximately 40% larger and contained approximately 70% more DNA than the parental cells. They were unable to grow in vitro in the absence of bicarbonate at pH less than 7.0, whereas the parental cells grew well at pH greater than or equal to 6.6. This difference in acid sensitivity was abolished in the presence of bicarbonate. In contrast to the parental MGH-U1 cells, the Na+/H+-deficient HSPD cells either failed to grow tumors, or showed severely retarded tumor growth when implanted into immune-deprived mice. This difference in tumor growth was not attributed to differences in cell size and DNA content, because Na+/H+ exchange-competent large cells (HLC), derived during the same proton suicide selection process as the HSPD cells, grew tumors at a rate close to that of the parental cells. Cells derived from the few tumors which grew after implantation of HSPD mutant cells were revertants which had regained Na+/H+ activity. HSPD cells also failed to form spheroids in culture, and the only spheroid formed consisted of revertant cells which had regained both Na+/H+ exchange activity and tumorigenic capacity. These results suggest that the Na+/H+ exchanger is important for tumor growth. PMID:2535690

Rotin, D; Steele-Norwood, D; Grinstein, S; Tannock, I

1989-01-01

189

Increased Na/H antiporter and Na/3HCO3 symporter activities in chronic hyperfiltration. A model of cell hypertrophy  

PubMed Central

The effect of chronic hyperfiltration, a model of cell hypertrophy, on H/HCO3 transporters was examined in the in vivo microperfused rat proximal tubule. Hyperfiltration was induced by uninephrectomy with subsequent increased dietary protein. After 2 wk the hyperfiltration group had a higher glomerular filtration rate (2.21 +/- 0.13 vs. 1.48 +/- 0.12 ml/min), associated with increased kidney weight (1.71 +/- 0.05 vs. 1.23 +/- 0.04 g). HCO3 absorptive rate measured in tubules perfused with an ultrafiltrate-like solution (25 mM HCO3) was higher in the hyperfiltration group (183 +/- 17 vs. 109 +/- 16 pmol/mm per min). The activities of the apical membrane Na/H antiporter and basolateral membrane Na/3HCO3 symporter were assayed using the measurement of cell pH [(2'7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein] in the doubly microperfused tubule in the absence of contact with native fluids. After 2 wk of hyperfiltration Na/H antiporter activity, assayed as the effect of luminal Na removal on cell pH, was increased 114%. Basolateral membrane Na/3HCO3 symporter activity, assayed as the effect of a decrease in peritubular [HCO3] (25 to 5 mM) or in peritubular [Na] (147 to 25 mM) in the absence of luminal and peritubular chloride, was increased 77 and 113%, respectively, in the hyperfiltration group. Steady-state cell pH, measured with physiologic, ultrafiltrate-like luminal and peritubular perfusates, was significantly higher in the hyperfiltration group (7.27 +/- 0.02 vs. 7.14 +/- 0.03). In similar studies, performed 24 h after uninephrectomy and protein feeding, kidney weight was increased 10%, Na/H antiporter activity 39%, and Na/3HCO3 symporter activity 46%. At this time cell pH was not different between the two groups. The results demonstrate that chronic hyperfiltration is associated with parallel increases in Na/H antiporter and Na/3HCO3 symporter activities. If a decrease in cell pH is the signal that triggers these adaptations, it occurs early, and the adaptations can be maintained in the absence of sustained cell acidification. PMID:1849958

1991-01-01

190

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

PubMed

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

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

1990-01-01

191

Links between hydrothermal environments, pyrophosphate, na(+), and early evolution.  

PubMed

The discovery that photosynthetic bacterial membrane-bound inorganic pyrophosphatase (PPase) catalyzed light-induced phosphorylation of orthophosphate (Pi) to pyrophosphate (PPi) and the capability of PPi to drive energy requiring dark reactions supported PPi as a possible early alternative to ATP. Like the proton-pumping ATPase, the corresponding membrane-bound PPase also is a H(+)-pump, and like the Na(+)-pumping ATPase, it can be a Na(+)-pump, both in archaeal and bacterial membranes. We suggest that PPi and Na(+) transport preceded ATP and H(+) transport in association with geochemistry of the Earth at the time of the origin and early evolution of life. Life may have started in connection with early plate tectonic processes coupled to alkaline hydrothermal activity. A hydrothermal environment in which Na(+) is abundant exists in sediment-starved subduction zones, like the Mariana forearc in the W Pacific Ocean. It is considered to mimic the Archean Earth. The forearc pore fluids have a pH up to 12.6, a Na(+)-concentration of 0.7mol/kg seawater. PPi could have been formed during early subduction of oceanic lithosphere by dehydration of protonated orthophosphates. A key to PPi formation in these geological environments is a low local activity of water. PMID:21461648

Holm, Nils G; Baltscheffsky, Herrick

2011-10-01

192

Na+/H+ Antiport Is Essential for Yersinia pestis Virulence  

PubMed Central

Na+/H+ antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na+/H+ antiport in Yersinia pestis virulence and found that Y. pestis strains lacking the major Na+/H+ antiporters, NhaA and NhaB, are completely attenuated in an in vivo model of plague. The Y. pestis derivative strain lacking the nhaA and nhaB genes showed markedly decreased survival in blood and blood serum ex vivo. Complementation of either nhaA or nhaB in trans restored the survival of the Y. pestis nhaA nhaB double deletion mutant in blood. The nhaA nhaB double deletion mutant also showed inhibited growth in an artificial serum medium, Opti-MEM, and a rich LB-based medium with Na+ levels and pH values similar to those for blood. Taken together, these data strongly suggest that intact Na+/H+ antiport is indispensable for the survival of Y. pestis in the bloodstreams of infected animals and thus might be regarded as a promising noncanonical drug target for infections caused by Y. pestis and possibly for those caused by other blood-borne bacterial pathogens. PMID:23774602

Minato, Yusuke; Ghosh, Amit; Faulkner, Wyatt J.; Lind, Erin J.; Schesser Bartra, Sara; Plano, Gregory V.; Jarrett, Clayton O.; Hinnebusch, B. Joseph; Winogrodzki, Judith; Dibrov, Pavel

2013-01-01

193

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-Jrgen; Clarke, Ronald J

2012-08-22

194

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

195

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

PubMed Central

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

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

2011-01-01

196

Schistosome Na,K-ATPase as a therapeutic target.  

PubMed

Na,K-ATPases are ubiquitous membrane-bound enzymes comprising ? and ? subunits. Here we clone a Na,K-ATPase ? homolog (designated SNaK1?) from the human parasitic platyhelminth, Schistosoma mansoni. The predicted protein is about 33 kDa, and contains a single transmembrane domain and multiple conserved motifs. SNaK1? and its previously cloned ?-subunit counterpart (SNaK1?) are both expressed throughout the schistosome life cycle. In adults, both subunits are detected in the tegumental membrane, likely functioning at the host-parasite interface in Na/K exchange. Both SNaK1 genes can be suppressed by RNAi using target-specific small inhibitory RNAs (siRNAs), and this severely debilitates the parasites both in vitro and in vivo. However, treating schistosomiasis by delivering the siRNAs hydrodynamically to infected mice has no detectable impact on worms. Additionally, treating schistosome-infected mice with the Na,K-ATPase inhibitor, ouabain, is ineffective. Nonetheless, since schistosomes are very susceptible to perturbation in SNaK1 expression, further work to identify other Na,K-ATPase inhibitors as anti-schistosome agents is warranted. PMID:23222953

Da'dara, Akram A; Faghiri, Zahra; Krautz-Peterson, Greice; Bhardwaj, Rita; Skelly, Patrick J

2013-02-01

197

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

NASA Astrophysics Data System (ADS)

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

Holm, Nils G.; Baltscheffsky, Herrick

2011-10-01

198

Biosensor Consists of Na -- Doped Hydroxyapatite Thin Film  

NASA Astrophysics Data System (ADS)

Hydroxyapatite (HAp) surface has an excellent ability of adsorption for functional biomolecules such as protein, DNA and so on. We have investigated the application of the HAp as a suitable material for biosensor. Thin film of the sodium -- doped HAp (Na -- HAp) is prepared in order to decrease the electric resistivity. We have studied variation of the resistance for the Na -- HAp thin films with the adsorption of the functional biomolecules. The sample were prepared by a pulsed laser deposition technique on porous alumina substrate. After the deposition, sample was post -- annealed in O2 / H2O atmosphere in order to crystallize the Na -- HAp. The powder X ray diffraction pattern shows the sample has a pure HAp structure. The gold comb electrodes were evaporated on the sample for the resistance measurement. The sample was set in pure water of 100 ml in a beaker. When Fetal Bovine Serum of 100 ?l was dropped in the beaker, the Na -- HAp shows the drastic change of the AC resistance (at 120 kHz). This result shows that the Na -- HAp will be one of the most effective materials for the biosensor applications.

Nishikawa, Hiroaki; Kawashima, Masami; Kawai, Tomoji

2005-03-01

199

Highly bright multicolor tunable ultrasmall ?-Na(Y,Gd)F?:Ce,Tb,Eu/?-NaYF? core/shell nanocrystals.  

PubMed

Herein, we report highly bright multicolor-emitting ?-Na(Y,Gd)F?:Ce,Tb,Eu/?-NaYF? nanoparticles (NPs) with precise color tunability. First, highly bright sub-20 nm ?-Na(Y,Gd)F?:Ce,Tb,Eu NPs were synthesized via a heating-up method. By controlling the ratio of Eu(3+) to Tb(3+), we generated green, yellow-green, greenish yellow, yellow, orange, reddish orange, and red emissions from the NP solutions via energy transfer of Ce(3+)? Gd(3+)? Tb(3+) (green) and Ce(3+)? Gd(3+)? Tb(3+)? Eu(3+) (red) ions under ultraviolet light illumination (254 nm). Because of Ce(3+) and Gd(3+) sensitization, Tb(3+) ions exhibited strong green emission. The decay time of Tb(3+) emission decreased from 4.0 to 1.4 ms as the Eu(3+) concentration was increased, suggesting that energy was transferred from Tb(3+) to Eu(3+). As a result, Eu(3+) emission peaks were generated and the emission color was transformed from green to red. Monodisperse sub-6 nm ?-Na(Y,Gd)F?:Ce,Tb,Eu NPs were synthesized through a simple reduction of the reaction temperature. Although fine color tunability was retained, their brightness was considerably decreased owing to an increase in the surface-to-volume ratio. The formation of a ?-NaYF? shell on top of the sub-6 nm NP core to produce ?-Na(Y,Gd)F?:Ce,Tb,Eu/?-NaYF? significantly increased the emission intensity, while maintaining the sub-10 nm sizes (8.7-9.5 nm). Quantum yields of the ultrasmall NPs increased from 1.1-6.9% for the core NPs to 6.7-44.4% for the core/shell NPs. Moreover, highly transparent core/shell NP-polydimethylsiloxane (PDMS) composites featuring a variety of colors, excellent color tunability, and high brightness were also prepared. PMID:23945563

Kim, Su Yeon; Woo, Kyoungja; Lim, Kipil; Lee, Kwangyeol; Jang, Ho Seong

2013-10-01

200

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

PubMed

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

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

2014-11-01

201

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

202

Molecular analysis of the Na+ channel blocking actions of the novel  

E-print Network

Molecular analysis of the Na+ channel blocking actions of the novel class I anti-arrhythmic agent of the Na+ channel, and that the drug may produce potent local anaesthetic or anti-arrhythmic action under; RSD 921; class I anti-arrhythmic; Xenopus oocytes; Na+ channel Abbreviations: rBIIA, rat brain IIA Na

Goldin, Alan L.

203

Growth and electronic properties of NaCl on HOPG  

NASA Astrophysics Data System (ADS)

We report the growth of cross-shaped islands of NaCl on highly oriented pyrolytic graphite (HOPG) and discuss the mechanism of formation and growth kinetics within the framework of diffusion limited aggregation (DLA). These structures are investigated using scanning probe microscopy. The shape and structure of these islands can be finely controlled by the deposition conditions. The islands exhibit large atomically flat surfaces which are ideal supports for investigations of the fundamental properties of deposited atoms, molecules or clusters. Bismuth nanostructures were deposited on the NaCl islands and were investigated via scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The tunneling spectra recorded for particles on NaCl are surprisingly similar to those measured for similar particles on HOPG. We suggest that this is due to a 'dead' layer commonly observed for Bi thin films.

Mahapatra, O.; Kowalczyk, P. J.; Brown, S. A.

2014-02-01

204

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

205

Intrinsic energy resolution of NaI(Tl)1  

NASA Astrophysics Data System (ADS)

The light output for ?10 mm10 mm and ?75 mm75 mm NaI(Tl) crystals and energy resolution were measured for ?-ray energies ranging from 16-1333 keV. These measurements enabled the observation of the light yield nonproportionality behavior and allowed the determination of the intrinsic resolution after correcting for the measured resolution for photomultiplier tube (PMT) statistics. The intrinsic resolution was then compared with the nonproportionality component. The latter was calculated using measured electron response, Monte Carlo N Particle code (MCNP4B), and the simplified cascade sequence for NaI(Tl). This comparison allowed the identification of the intrinsic resolution component associated with ?-rays. Consequently, it was shown that the ?-ray component is the most dominant component of the NaI(Tl) intrinsic resolution.

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

2002-05-01

206

Characterization of the Na?/H? antiporter from Yersinia pestis.  

PubMed

Yersinia pestis, the bacterium that historically accounts for the Black Death epidemics, has nowadays gained new attention as a possible biological warfare agent. In this study, its Na?/H? antiporter is investigated for the first time, by a combination of experimental and computational methodologies. We determined the protein's substrate specificity and pH dependence by fluorescence measurements in everted membrane vesicles. Subsequently, we constructed a model of the protein's structure and validated the model using molecular dynamics simulations. Taken together, better understanding of the Yersinia pestis Na?/H? antiporter's structure-function relationship may assist in studies on ion transport, mechanism of action and designing specific blockers of Na?/H? antiporter to help in fighting Yersinia pestis -associated infections. We hope that our model will prove useful both from mechanistic and pharmaceutical perspectives. PMID:22102858

Ganoth, Assaf; Alhadeff, Raphael; Kohen, Dovrat; Arkin, Isaiah T

2011-01-01

207

Superconducting properties and electronic structure of NaBi.  

PubMed

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

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

2014-05-28

208

High-NA HPCS optical fibers for medical diagnosis and treatment  

NASA Astrophysics Data System (ADS)

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

Skutnik, Bolesh J.

2010-02-01

209

Electrogenic 2 Na+/1 H+ exchange in crustaceans.  

PubMed

Hepatopancreatic brush border membrane vesicles of the freshwater prawn, Macrobrachium rosenbergii and the marine lobster, Homarus americanus exhibited 22Na uptake which was Cl-independent, amiloride sensitive, and stimulated by a transmembrane H gradient (Hi greater than Ho). Sodium influx by vesicles of both species were sigmoidal functions of [Na]o, yielding Hill coefficients that were not significantly different (P greater than 0.5) than 2.0. Estimations of half-saturation constants (KNa) were 82.2 mM (prawn) and 280.1 mM (lobster), suggesting a possible adaptation of this transporter to environmental salinity. Trans-stimulation and cis-inhibition experiments involving variable [H] suggested that the exchangers in both species possessed single internal cation binding sites (pK 6.5-6.7) and two external cation binding sites (prawn, pK 4.0 and 5.7; lobster pK 3.5 and 6.1). Similar cis inhibition studies using amiloride as a competitive inhibitor of Na uptake supported the occurrence of dual external sites (prawn, Ki50 and 1520 microM; lobster Ki9 and 340 microM). Electrogenic Na/H exchange by vesicles from both crustaceans was demonstrated using equilibrium shift experiments where a transmembrane potential was used as the only driving force for the transport event. Transport stoichiometries of the antiporters were determined using Static Head analysis where driving forces for cation transfer were balanced using a 10:1 Na gradient, a 100:1 H gradient, and a stoichiometry of 2.0. These electrogenic 2 Na/1 H exchangers appear thermodynamically capable of generating sufficient gastric acidification for organismic digestive activities. PMID:2167376

Ahearn, G A; Franco, P; Clay, L P

1990-07-01

210

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

NASA Astrophysics Data System (ADS)

Sodium superoxide (NaO2) is believed to be a major sink for meteor-ablated Na in the upper atmosphere. However, the rate constant for the reaction between NaO2 and O is not known, and its determination is the subject of this study. NaO2 was produced by the reaction between Na vapor, an excess of O2, and the carrier gas N2 in the upstream section of a fast flow tube reactor. Excess atomic O was then added, so that a steady state developed in which the sodium was partitioned between its atomic form and a variety of oxides. The steady state fraction of atomic Na, monitored by laser-induced fluorescence, was then observed as a function of [O] and [O2], from which it was deduced that k(NaO2 + O) = (2.2 1.0) 10-11 cm3 molecule-1 s-1 at 300 K (3? uncertainty). As a prelude to this experiment, the recombination reaction between O2 and Na was studied by the conventional flow tube technique, yielding k(Na + O2 + N2) = (3.14 0.20) 10-30 (300/T)-(1.520.27) cm6 molecule-2 s-1. These experimental results were then incorporated into a one-dimensional model of sodium in the upper atmosphere between 65 and 110 km. It is shown that formation of NaHCO3 rather than NaO2 is the dominant removal process for atomic Na below 90 km. This new model, whose only important assumption is the rate constant for the reaction NaHCO3 + H ? Na + H2CO3, predicts a seasonal variation of the atomic Na layer in excellent agreement with recent lidar observations at 40 and 69N and also demonstrates that temperature fluctuations produced by gravity waves should induce significant chemical responses in the Na layer below 88 km.

Helmer, Magdalena; Plane, John M. C.

1993-12-01

211

Possible selective adsorption of enantiomers by Na-montmorillonite  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

212

Tb/Na tobermorite: Thermal behaviour and high temperature products  

NASA Astrophysics Data System (ADS)

By heating a sample of Tb/Na tobermorite we obtained a phase which was identified through its X-ray diffraction (XRD) pattern, as terbium silicate apatite. Subsequently this compound has been directly prepared by solid state reaction and we carried out a structural refinement from XRD data in space group P6 3/ m obtaining cell parameters a=9.39199(4) and c=6.84041(5) . Terbium silicate apatite heated in melted NaF led to Tb 4O 7 crystals.

Garra, Walter; Marchetti, Fabio; Merlino, Stefano

2009-06-01

213

Supporting Information to "Influence of Salt Purity on Na+  

E-print Network

.5 1.0 1.5 2.0 decrease with time a PA on UP grade 0.6 M NaCl 10-15 min 20-25 min 35-40 min 45-50 min 55-60 min VSFGIntensity(a.u.) increase with time b PA on ACS grade 0.6 M NaCl 10-15 min 20-25 min 35-40 min 45-50 min 55-60 min VSFGIntensity(a.u.) Wavenumber (cm -1 ) 1350 1400 1450 1500 1550 1600 0.0 0

214

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

215

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. PMID:6090578

1984-01-01

216

NA62 experiment: Measurement of BR(K+ ? ?+?nubar)  

NASA Astrophysics Data System (ADS)

The NA62 experiment aims to measure the very rare kaon decay K+ ? ?+?nubar at the CERN SPS. The expected branching ratio has been recently estimated within the Standard Model to be (8.22 0.84) 10-11. From the experimental side, 7 events has been found by E787/949 experiments at BNL providing a measurement of the branching ratio of (1.73+1.15-1.05) 10-10. The aim of NA62 is to collect ~100 events in two years of data taking with a 10% background. A description of the setup and the R&D program is presented.

Cortina Gil, Eduardo

2009-06-01

217

Complex microwave conductivity of Na-DNA powders  

E-print Network

We report the complex microwave conductivity, $\\sigma=\\sigma_1-i\\sigma_2$, of Na-DNA powders, which was measured from 80 K to 300 K by using a microwave cavity perturbation technique. We found that the magnitude of $\\sigma_1$ near room temperature was much larger than the contribution of the surrounding water molecules, and that the decrease of $\\sigma_1$ with decreasing temperature was sufficiently stronger than that of the conduction of counterions. These results clearly suggest that the electrical conduction of Na-DNA is intrinsically semiconductive.

H. Kitano; K. Ota; A. Maeda

2006-08-01

218

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.

2011-10-01

219

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

220

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. PMID:11916841

Pandit, Sagar A; Berkowitz, Max L

2002-01-01

221

Beta-Gamma-Angular Correlation in Na-20  

E-print Network

Station, Texas 77843 D. P. May and D. M. Tanner Cyclotron Institute, Texas A AM University, College Station, Texas 77843 (Received 19 November 1980) The P-y angular correlation for the decay of "Na has been measured using a symmetric four detector... for the two correlations, we find 2245 1981 The American Physical Society 2246 R. K. YRIBBLK, D. P. MAY, AND D. M. TANNER (5) 6165 C (7) where a'(E,)=E,("Na)+E,("F)=16.6 MeV. By invoking the conserved vector current (CVC) hypothesis, ' the weak...

Tribble, Robert E.; May, D. P.; Tanner, D. M.

1981-01-01

222

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

223

Differential effects of substrates on three transport modes of the Na+/K(+)-ATPase.  

PubMed

With a purified Na+/K(+)-ATPase preparation reconstituted into phospholipid vesicles, Na+/K+, Na+/Na+, and uncoupled Na+ transport were studied using three nucleotides and five substrates of the K(+)-phosphatase reaction that this enzyme also catalyzes. For Na+/K+ exchange, CTP was half as effective as ATP and GTP one-twentieth; of the phosphatase substrates only carbamyl phosphate and 3-O-methylfluorescein phosphate produced significant transport and at merely 1% of the rate with ATP. For Na+/Na+ exchange, comparable rates of transport were produced by ATP, CTP, carbamyl phosphate and acetyl phosphate, although the actual rate of transport with ATP was only 2.4% of that for Na+/K+ exchange; slower rates occurred with GTP (69%), 3-O-methylfluorescein phosphate (51%), and nitrophenyl phosphate (33%). Only umbelliferone phosphate was ineffective. For uncoupled Na+ transport results similar to those for Na+/Na+ exchange were obtained, but the actual rate of transport was still slower, 1.4% of that for Na+/K+ exchange. Thus, not only nucleotides but a variety of phosphatase substrates (which are phosphoric acid mixed anhydrides) can phosphorylate the enzyme at the high-affinity substrate site to form the E1P intermediate of the reaction sequence. Oligomycin inhibited Na+/K+ exchange with ATP by half, but with carbamyl phosphate not at all; with CTP the inhibition was intermediate, one-fourth. By contrast, oligomycin inhibited Na+/Na+ exchange by one-fifth with all three substrates. A quantitative, steady-state kinetic model accounts for the relative magnitudes of Na+/K+ and Na+/Na+ exchanges with ATP, CTP, and carbamyl phosphate as substrates, as well as the extents of inhibition by oligomycin. The model requires that even when Na+ substitutes for K+ a slow step in the reaction sequence is the E2 to E1 conformational transition. PMID:2156564

Guerra, M; Robinson, J D; Steinberg, M

1990-03-30

224

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

Microsoft Academic Search

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

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

2009-01-01

225

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

E-print Network

In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3 Jong at high temperatures. After dehydration at 288 °C, the Na2Nb2O6-H2O becomes significantly destabilized

Wang, Zhong L.

226

Synthesis, photophysical properties, and photocatalytic applications of Bi doped NaTaO3 and Bi doped Na2Ta2O6 nanoparticles  

NASA Astrophysics Data System (ADS)

Phase formation and photophysical properties of bismuth doped sodium tantalum oxide (perovskite, defect pyrochlore) nanoparticles prepared by a hydrothermal method were studied in detail. It was revealed that the synthesis conditions like NaOH concentration and bismuth precursor (NaBiO32H2O) markedly affect the crystal structure of sodium tantalum oxide. At low NaOH concentration and high bismuth precursor (NaBiO32H2O) content, Bi doped Na2Ta2O6 (defect pyrochlore) phase was predominantly formed, while at higher NaOH concentration, Bi doped NaTaO3 (perovskite) phase was formed. It was observed that the defect pyrochlore (Bi doped Na2Ta2O6) phase was formed and stabilized by the presence of dopant precursor (NaBiO32H2O). The chemical analysis of the samples confirmed the doping of Bi3+ cations in both phases. Doping of bismuth enabled visible light absorption up to 500 nm in perovskite and defect pyrochlore type sodium tantalum oxide. Bi doped NaTaO3 samples showed better performance for the photocatalytic degradation of rhodamine B than that of Bi doped Na2Ta2O6, under visible light irritation (?>420 nm). The present results shed light on phase formation of sodium tantalate and these results are useful in understanding properties of NaTaO3 based compounds, synthesized by the hydrothermal method.

Kanhere, Pushkar; Tang, Yuxin; Zheng, Jianwei; Chen, Zhong

2013-12-01

227

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

228

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

PubMed

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

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

2014-08-01

229

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

PubMed

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

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

2011-03-01

230

Electron transfer and ionization in collisions of He-like ions with Na(3s) and Na(3p)  

NASA Astrophysics Data System (ADS)

Single electron transfer and ionization in collisions of He-like ions (N5+, O6+, Ne8+) and Na has been investigated both experimentally and theoretically at energies around the matching velocity of the valence electron (2 to 10 keV/amu). State selective cross sections and scattering angle distributions were obtained using recoil-ion momentum spectroscopy in combination with a magneto-optically cooled Na atom target. A strong dependence of the relative cross sections on the collision energy is observed. The results are compared with Classical-Trajectory Monte Carlo (CTMC) calculations and show an overall very good agreement.

Blank, I.; Otrantcr, S.; Meinema, C.; Olson, R. E.; Hoekstra, R.

2012-11-01

231

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

PubMed

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

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

2005-06-01

232

Optimization of Automated Float Glass Lines Byungsoo Na, Shabbir Ahmed  

E-print Network

Optimization of Automated Float Glass Lines Byungsoo Na, Shabbir Ahmed , George Nemhauser and Joel of Scope and Purpose Flat glass is approximately a $20 billion/year industry worldwide, with almost all flat glass products being manufactured on float glass lines. New technologies are allowing float glass

Ahmed, Shabbir

233

Stainless Steel NaK Circuit Integration and Fill Submission  

NASA Technical Reports Server (NTRS)

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

Garber, Anne E.

2006-01-01

234

New Measurement of ?-? Angular Correlation in ^22Na  

NASA Astrophysics Data System (ADS)

We have measured the ?-? directional correlation in the hindered decay ^22 Na (3^+) arrow ^22Ne (2^+) using the Gammasphere array at LBNL. Our measurement contributes to determining a complete set of weak form factors for the ^22Na ? decay, testing corrections to allowed ? decay to second recoil order. The aim is to resolve a long-standing discrepancy between experiment and allowed-order theory in the electron capture to positron emission ratios. We used a 6 ?Ci source of ^22Na in the center of Gammasphere, a spherical array of 110 Ge detectors. The ?^+ is detected with a 3 mm thick plastic scintillator with 8% solid angle. The ?^+ decay is followed by a 1.275 MeV ? from the ^22Ne 2^+ state. We search for a directional dependence of the emitted ?'s detected in coincidence with a ? of form 1 + A\\cos^2 ?, with ? the angle between the ? and the individual Ge detectors, and A of order 10-3. Variable Ge detector efficiency is normalized by dividing coincident ? counts by single 1.275 MeV ?'s. Fitting the results versus ? - ? angle using gates on the ?^+ energy yields the energy-dependent A, which is sensitive to a linear combination of second-order form factors. Current data and analysis, and implications for ^22Na form factors will be presented.

Vetter, Paul; Bowers, Chris; Freedman, Stuart; Fujikawa, Brian; Reich, Jurgen; Shang, Song; Wasserman, Eric

1997-10-01

235

Free Energy for the Permeation of Na+ Ions and Their  

E-print Network

Free Energy for the Permeation of Na+ and Cl- Ions and Their Ion-Pair through a Zwitterionic-mail: ikhavru@mccammon.ucsd.edu Abstract: Understanding the mechanism of ion permeation across lipid bilayers for the ion permeation in disagreement with predictions from the simple electrostatic models. In this paper we

Lu, Benzhuo

236

High precision measurements of Na-26 beta(-) decay  

E-print Network

High-precision measurements of the half-life and beta-branching ratios for the beta(-) decay of Na-26 to Mg-26 have been measured in beta-counting and gamma-decay experiments, respectively. A 4 pi proportional counter and fast tape transport system...

Grinyer, GF; Svensson, CE; Andreoiu, C.; Andreyev, AN; Austin, RAE; Ball, GC; Chakrawarthy, RS; Finlay, P.; Garrett, PE; Hackman, G.; Hardy, John C.; Hyland, B.; Iacob, VE; Koopmans, KA; Kulp, WD; Leslie, JR; Macdonald, JA; Morton, AC; Ormand, WE; Osborne, CJ; Pearson, CJ; Phillips, AA; Sarazin, F.; Schumaker, MA; Scraggs, HC; Schwarzenberg, J.; Smith, MB; Valiente-Dobon, JJ; Waddington, JC; Wood, JL; Zganjar, EF.

2005-01-01

237

Transport of aromatic molecules in NaY zeolite powders  

SciTech Connect

This paper reports on Xenon-120 NMR that is used to probe macroscopic distributions of aromatic molecules adsorbed in a packed bed of 1-{mu}m NaY zeolite particles. Relative rates of guest transport through the intracrystalline (micro) and intercrystalline (macro) pores play a unique role in the axial distribution of sorbate molecules, such as hexamethylbenzene, in a zeolite powder. Xenon-129 NMR spectra show that a sharp HMB adsorption front advances through a bed of dehydrated NaY crystallites at 523 K. However, at 573 K or in the presence of coadsorbed water, HMB species disperse through the bed without forming a sharp boundary between adsorption zones. When guest transport is controlled by pseudosteady-state diffusion in the macropores, axial penetration of the bed by vapor-phase guest species occurs in a sharp adsorption front. A shrinking-core transport model then quantitatively estimates the intracrystalline diffusivities of HMB in dehydrated and partially hydrated NaY zeolite of 10{sup {minus}11} and 10{sup {minus}13} m{sup 2}/s, respectively, at 523 K. Xenon- 129 NMR proves to be a powerful tool for probing adsorbed guest distribution in zeolites, allowing relative time scales to be established for transport of molecular guests in NaY powders.

Chmelka, B.F.; Gillis, J.V.; Petersen, E.E.; Radke, C.J.

1990-10-01

238

FEORAGAN RUADH NA GAIDHEALTACHD Scottish Squirrel Group Update September 2011  

E-print Network

FEORAGAN RUADH NA GAIDHEALTACHD Scottish Squirrel Group Update September 2011 Strongholds Guidance is in production. Pilot sites are underway, Julia Garritt to update the meeting. Grey squirrel news No further records since Skye in December 2010. Plan to set up network of grey squirrel `panic bags' around

239

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

E-print Network

Education: Expanding arts learning opportunities for children and teens in school and beyond; (5) AudienceGrant Title: WALLACE FOUNDATION Funding Opportunity Number: N/A Agency/Department: The Wallace this approach strengthens the effectiveness of their funding. But it also means Wallace rarely funds unsolicited

Farritor, Shane

240

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

E-print Network

of significant promise. Special funding priorites are given to: education, human services, arts, humanities its capital in support of people through education, human services, the arts, the humanitiesGrant Title: COOPER FOUNDATION Funding Opportunity Number: N/A Agency/Department: Cooper Foundation

Farritor, Shane

241

Benefiting from Polarization: Effects at High-NA Imaging  

E-print Network

157nm F2 Laser Mirror MirrorMirror Illuminator Mask Projection Lens Wafer Polarizer F2 Laser Mirror MirrorMirror Illuminator Mask Projection Lens Wafer Polarizer linearly polarized output beam unpolarizedBenefiting from Polarization: Effects at High-NA Imaging Bruce W. Smith L. Zavyalova, A. Estroff, Y

Zanibbi, Richard

242

National Aeronautics and Space Administration NaNotechNology Roadmap  

E-print Network

National Aeronautics and Space Administration · NaNotechNology Roadmap Technology Area 10 Michael A of fourteen technology area roadmaps, recommending the overall technology investment strategy in these areas, NASA plans updates to its integrated technology roadmap on a regular basis. #12;exeCuTive Summary

Waliser, Duane E.

243

Isolation of22Na for intense positron sources  

NASA Astrophysics Data System (ADS)

A method of removing22Na from Al via distillation is investigated. Distillation is rapid (?10 minutes) and nearly quantitative. When the distilled vapor is directed by a flow of He gas the deposit may be localized fairly well and easily recovered with water.

Griffin, H. C.; Steiger, T. D.; van House, J.; Skalsey, M.; Conti, R.; Rich, A.; Zitzewitz, P. W.

1989-03-01

244

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

E-print Network

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

Brand, Paul H.

245

Exploring Neutron-Rich Oxygen Isotopes with MoNA  

E-print Network

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

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

2007-08-20

246

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

247

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

E-print Network

Grant Title: STARR FOUNDATION Funding Opportunity Number: N/A Agency/Department: Starr Foundation: The Foundation funds organizations that provide need-based financial aid to students seeking to attend secondary. The Foundation makes significant grants to large cultural institutions, smaller arts organizations, community

Farritor, Shane

248

Synthesis of Na-zeolites from fly ash  

Microsoft Academic Search

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

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

1997-01-01

249

A Lepton Universality Test at CERN NA62 Experiment  

E-print Network

The NA62 experiment at CERN collected a large sample of K+ --> enu decays during a dedicated run in 2007, aiming at a precise test of lepton universality by measurement of the helicity suppressed ratio RK = BR(K+ --> enu)/BR(K+ --> munu). A preliminary result of the analysis of a partial data sample of 51089 K+ --> enu candidates is presented.

Evgueni Goudzovski

2010-05-07

250

POWER FROM NA COOLED REACTOR REACTOR DESIGN AND FEASIBILITY PROBLEM  

Microsoft Academic Search

Work done on the study of a Na cooled, graphite moderated nuclear ; reactor for power production is summarized. The preliminary design calculations ; and results are described for a heterogeneous, thermal reactor using rod type ; fuel elements of slightly enriched U. The total heat capacity is 300,000 kw with ; a nominal electric power producing capacity of 75,000

D. R. Bennion; R. L. Hickmott; N. A. Krohn; W. J. McCarthy; R. A. Moore; H. J. Stumpf; L. A. Waldman

1952-01-01

251

Monitorizao eletroencefalogrfica ambulatorial na epilepsia de difcil controle da infncia  

Microsoft Academic Search

RESUMO - O objetivo deste estudo foi analisar atravs da monitorizao eletroencefalogrfica ambulatorial contnua e prolongada a distribuio temporal de descargas paroxsticas em sono e em viglia de crianas e adolescentes com epilepsia de difcil controle medicamentoso. Foram selecionadas 21 pacientes na faixa etria de 4 a 17 anos de idade com epilepsia de difcil controle medicamentoso, sendo 52,3 %

Sueli Rizzutti; Mauro Muszkat; Carlos Jos Reis de Campos

2001-01-01

252

Adolescncia e violncia: a psicanlise na prtica social  

Microsoft Academic Search

Este projeto foi iniciado em 1994, culminando em 97 com a publicao do livro Adolescncia e Violncia: Conseqncias da Rea- lidade Brasileira (Levisky,1997a). Damos continuidade a esta iniciativa, abordando o binmio ado- lescncia e violncia a partir da apreenso psicanaltica destes fenme- nos e seus desdobramentos na prtica social. So trabalhos oriundos da experincia clnica de psicanalistas, em sua maioria,

David Lo Levisky

253

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

254

Global structure of small Na clusters in different approaches  

Microsoft Academic Search

We compare the shapes of small Na clusters as they result from the jellium model, the cylindrically averaged pseudopotential scheme, and the distance-dependent tight-binding approach. Although these are three distinctively different approaches, we find a good agreement amongst the results, showing that all three models, taken in their appropriate domain of descriptive power, give an equally reliable picture of metal

F. Spiegelmann; R. Poteau; B. Montag; P.-G. Reinhard

1998-01-01

255

Purification of the cardiac Na+-Ca2+ exchange protein.  

PubMed

We have used fractionation procedures to enrich solubilized cardiac sarcolemma in the Na+-Ca2+ exchange protein. Sarcolemma is extracted with an alkaline medium to remove peripheral proteins and is then solubilized with decylmaltoside. Next, the exchanger is applied to DEAE-Sepharose and eluted with high salt. The DEAE fraction is applied to WGA-agarose, and a small fraction of protein, enriched in the exchanger, can be eluted by changing the detergent to Triton X-100. This fraction is reconstituted into asolectin proteoliposomes for measurement of Na+-Ca2+ exchange activity and gel electrophoresis. The purified fraction has a Na+-Ca2+ exchange activity of 600 nmol Ca2+/mg of protein per s at 10 microM Ca2+ and a purification factor of about 30 as compared with control reconstituted sarcolemmal vesicles. Ca2+-Ca2+ exchange and Na+-Ca2+ exchange activities were both present in the same final reconstituted vesicles indicating that the same protein is responsible for both transport activities. SDS-PAGE reveals two prominent protein bands at 70 and 120 kDa. After mild chymotrypsin treatment (1 microgram/ml), there is no loss of exchange activity, but the 120 kDa band disappears and the 70 kDa band becomes more dense. This suggests that the 70 kDa band is due to an active proteolytic fragment of the 120 kDa protein. Under non-reducing gel conditions, only a single protein band is seen with an apparent molecular weight of 160 kDa. Antibodies to the purified exchanger preparation are able to immunoprecipitate exchange activity and confirm that the 70 kDa protein derives from the 120 kDa protein. We propose that both the 70 and 120 kDa proteins are associated with the Na+-Ca2+ exchanger. PMID:3191125

Philipson, K D; Longoni, S; Ward, R

1988-11-22

256

Surface color centers on NaCl(001)  

NASA Astrophysics Data System (ADS)

Charging effects and probe induced damage usually render impossible the investigation of ionic crystal surfaces by means of many of the conventional surface science tools, like e.g. low-energy electron diffraction (LEED). A way out of this dilemma is using low current densities on surfaces of thin epitaxial insulator films grown on a conducting substrate. We studied the creation of color centers in and on epitaxial NaCl on Ge(001) by means of ELS-LEED, a unique combination of high resolution LEED and energy loss spectroscopy (ELS). Surface color centers determine the chemical reactivity of the NaCl(001) surface as will be demonstrated for the adsorption of water. - Different kinetics of formation permit the identification of different types of surface color centers. At temperatures below 200 K prolonged low-energy electron bombardment creates predominantly surface F- and M-centers appearing as randomly distributed static point defects. Only at room temperature does diffusion lead to the formation of Na clusters and colloids. When water is present anion vacancies are transformed into OH^--centers. During the formation of the two-dimensional condensed phase of H_2O on NaCl(001), OH^--centers act as nucleation centers for H_2O clusters. These limit the long-range order of the 2D-phase, reducing the superstructure from a c(2x12) symmetry as formed on annealed NaCl films to c(2x4). As a model we present an ice-like bilayer with a vertical modulation.

Zielasek, V.; Hildebrandt, T.; Henzler, M.

1998-03-01

257

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

PubMed Central

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

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

2013-01-01

258

Stoichiometric relationship between Na(+) ions transported and glucose consumed in human erythrocytes: Bayesian analysis of (23)Na and (13)C NMR time course data.  

PubMed

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

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

2013-04-16

259

Synthesis of Li (x)Na (2-x)Mn 2S 3 and LiNaMnS 2 through redox-induced ion exchange reactions  

NASA Astrophysics Data System (ADS)

Na 2Mn 2S 3 was oxidatively deintercalated using iodine in acetonitrile to yield Na 1.3Mn 2S 3, with lattice constants nearly identical to that of the reactant. Lithium was then reductively intercalated into the oxidized product to yield Li 0.7Na 1.3Mn 2S 3. When heated, this metastable compound decomposed to form a new crystalline compound, LiNaMnS 2, along with MnS and residual Na 2Mn 2S 3. Single crystal X-ray diffraction structural analysis of LiNaMnS 2 revealed that this compound crystallizes in P-3 m1 with cell parameters a=4.0479(6) , c=6.7759(14) , V=96.15(3) 3 ( Z=1, w R2=0.0367) in the NaLiCdS 2 structure-type.

Luthy, Joshua A.; Goodman, Phillip L.; Martin, Benjamin R.

2009-03-01

260

Two novel Zintl compounds Na 12Ge 8Sn and Na 15Ge 8SnP: Single crystal and electronic structures  

NASA Astrophysics Data System (ADS)

Two mixed anionic Zintl phases, Na 12Ge 8Sn and Na 15Ge 8SnP, have been synthesized and structurally characterized. Na 12Ge 8Sn crystallizes in the tetragonal space group P4 12 12 (#92, a = 14.1172(2) , c = 21.8483(7) , V = 4354.3(2) 3, Z = 8, and R/ wR = 0.0481/0.1213) and Na 15Ge 8SnP crystallizes in the orthorhombic space group Cmcm (#63, a = 17.517(4) , b = 12.890(3) , c = 11.111(2) , V = 2508.7(9) 3, Z = 4, and R/ wR = 0.0313/0.0669). Both compounds adopt new structure types and are made up of isolated Na + cations, anionic (Ge 4) 4- tetrahedral clusters, and Sn 4- or P 3- anions. The structure of Na 12Ge 8Sn can be described as a square packing of two kinds of columns, highly distorted Sn centered Na icosahedra chains ([NaSn]5+?1) and highly distorted Na(1) centered anti-rectangular prism (four (Ge 4) 4- and four Na, [Na()2]5-?1) chains. The structure of Na 15Ge 8SnP is composed of cationic [NaSnP]8+?1 saw tooth-like chains, which are made up of Sn centered Na bicapped hexagonal prisms and P centered tricapped trigonal prisms, extending along the c axis with anionic (Ge 4) 4- tetrahedral clusters between the chains. The electronic structures have been studied using density functional theory.

Dong, Yongkwan; Ranjan, Chinmoy; DiSalvo, Francis J.

2008-05-01

261

ber den Fremdionengehalt einiger Alkalihalogenid- phosphore  

Microsoft Academic Search

Zusammenfassung Auer den in der Zusammenfassung genannten Ergebnissen enthlt die Arbeit noch folgende experimentelle Tatsachen. 1. Den Einflu steigender Konzentration auf die Absorptionsspektra von Tl-haltigen Phosphoren (Fig. 4 a bis c). 2. Die Absorptions-spektra der Chloride und Bromide von Tl und Pb in wsseriger Lsung, teils frei, teils nach Bildung von Komplexsalzen (Fig. 6 a, b; 7 a, b; 8

Werner Koch

1929-01-01

262

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

E-print Network

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

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

2007-01-08

263

Na-O anticorrelation and horizontal branches. V. The Na-O anticorrelation in NGC 6441 from Giraffe spectra  

NASA Astrophysics Data System (ADS)

Aims:We present an analysis of FLAMES-Giraffe spectra for several bright giants in NGC 6441, to investigate the presence and extent of the Na-O anticorrelation in this anomalous globular cluster. Methods: The field of NGC 6441 is very crowded, with severe contamination by foreground (mainly bulge) field stars. Appropriate membership criteria were devised to identify a group of 25 likely cluster members among the about 130 stars observed. Combined with the UVES data obtained with the same observations (Gratton et al. 2006), high dispersion abundance analyses are now available for a total of 30 stars in NGC 6441, 29 of them having data for both O and Na. The spectra were analyzed by a standard line analysis procedure; care was taken to minimize the impact of the differential interstellar reddening throughout the cluster, and to extract reliable information from crowded, and moderately high S/N (30-70), moderately high resolution (R 23 000) spectra. Results: NGC 6441 has the typical abundance pattern seen in several other globular clusters. It is very metal-rich ([Fe/H] = -0.34 0.02 0.04 dex). There is no clear sign of star-to-star scatter in the Fe-peak elements. The ?-elements Mg, Si, Ca, and Ti are overabundant by rather large factors, suggesting that the cluster formed from material enriched by massive core collapse SNe. The O-Na anticorrelation is well defined, with about 1/4 of the stars being Na-rich and O-poor. One of the stars is a Ba-rich and moderately C-rich star. Such stars are rare in globular clusters. Conclusions: .The distribution of [Na/O] ratios among RGB stars in NGC 6441 appears similar to the distribution of colors of stars along the horizontal branch. The fraction of Na-poor, O-rich stars found in NGC 6441 agrees well with that of stars on the red horizontal branch of this cluster (in both cases about 80%), with a sloping distribution toward lower values of [O/Na] (among RGB stars) and bluer colors (among HB stars). Based on data collected at the European Southern Observatory with the VLT-UT2, Paranal, Chile (ESO Program 073.D-0211). Full Table [see full text] is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/464/953

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

2007-03-01

264

Energetics of phosphate frameworks containing zinc and cobalt: NaZnPO 4, NaH(ZnPO 4) 2, NaZnPO 4H 2O, NaZnPO 4 {4}/{3}H 2O, and NaCo xZn 1-xPO 4 {4}/{3}H 2O  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry and high temperature oxide melt solution calorimetry were used to study the enthalpy of the ?- ? phase transformation of NaZnPO 4 and enthalpies of formation of ?-NaZnPO 4, NaH(ZnPO 4) 2, NaZnPO 4H 2O, and NaCo xZn 1-xPO 4 {4}/{3}H 2O ( x=0, 0.1, 0.2, 0.3). The enthalpies of formation from the oxides of cobalt substituted in NaZnPO 4 {4}/{3}H 2O do not depend on cobalt content, confirming similar acid-base interactions for Zn-PO 4 and Co-PO 4. While water molecules stabilize zinc phosphate frameworks through solvating a cation or forming extra hydrogen bonds, the partial substitution of water for sodium oxide to form NaH(ZnPO 4) 2 represents the formation of an acidic compound with weaker acid-base interactions and less exothermic enthalpy of formation from oxides than Na 2(ZnPO 4) 2.

Le, So-Nhu; Navrotsky, Alexandra

2007-09-01

265

Quantum mechanical calculation of 23 Na NMR shieldings in silicates and aluminosilicates  

Microsoft Academic Search

To assist in the assignment and interpretation of 23Na NMR spectra in silicate and aluminosilicate minerals and glasses we have calculated the 23Na NMR shieldings and the electric field gradients (EFG) at the Na for a number of Na-containing species. Included are Na(OH2)\\u000a n\\u000a \\u000a +, n?=?1, 2, 4, 5, 6 and 8, and Na+ complexes with SiH3OH, SiH3ONa and O(SiH3)2.

J. A. Tossell

1999-01-01

266

INTEX-NA: Intercontinental Chemical Transport Experiment - North America  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

267

Stabilization of Na,K-ATPase by ionic interactions.  

PubMed

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

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

2008-04-01

268

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

PubMed

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

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

2014-03-01

269

Performance comparison of MoNA and LISA neutron detectors  

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

270

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

271

Na,K-ATPase: Isoform structure, function, and expression  

Microsoft Academic Search

An interesting feature of the Na,K-ATPase is the multiplicity of a and isoforms. Three isoforms exist for the a subunit, a1, a2, and a3, as well for the subunit, 1, 2, and 3. The functional significance of these isoforms is unknown, but they are expressed in a tissue- and developmental-specific manner. For example, all three isoforms of the

Jerry B. Lingrel

1992-01-01

272

Background understanding and improvement in NaI scintillators  

NASA Astrophysics Data System (ADS)

Sodium Iodide scintillators are very interesting particle and radiation detectors. Low background requirements could limit their application in a variety of fields. We report the e.orts to understand and reduce the background in a set of 14 NaI detectors, stored underground since 1988, undertaken in the frame of the ANAIS experiment [1] in several directions, including PSD techniques, Monte Carlo simulations and detector upgrading.

Amar, J.; Beltrn, B.; Carmona, J. M.; Cebrin, S.; Garca, E.; Gmez, H.; Irastorza, I. G.; Luzn, G.; Martnez, M.; Morales, J.; Ortiz de Solrzano, A.; Pobes, C.; Puimedn, J.; Rodrguez, A.; Ruz, J.; Sarsa, M. L.; Torres, L.; Villar, J. A.

2006-05-01

273

Radiation-induced creep of confined NaCI  

Microsoft Academic Search

Samples of pure single crystals of NaC1 and of a natural rock salt were simultaneously gamma-irradiated at an approximate constant dose rate (15 kGy\\/h) and a constant temperature (100C) and for different lengths of time, resulting in integrated doses ranging from 0.02 to 44.6 MGy. Microstructural analysis showed that both incipient deformation structures and very advanced recovery structures develop during

A. Garca Celma; H. Donker

1994-01-01

274

Mode coupling in low NA plastic optical fibers  

NASA Astrophysics Data System (ADS)

Using the power flow equation and experimental measurements, investigated in this article is the state of mode coupling in low NA (0.3) step-index plastic optical fibers for laser beam launch. Results show the coupling length Lc at which the equilibrium mode distribution is achieved and the length zs of the fiber required for achieving the steady-state mode distribution. Numerical results obtained using the power flow equation agree well with experimental measurements.

Savovi?, Svetislav; Kova?evi?, Milan S.; Djordjevich, Alexandar; Baji?, Jovan S.; Stupar, Dragan Z.; Stepniak, Grzegorz

2014-08-01

275

Third-Order Elastic Constants of NaF  

Microsoft Academic Search

The complete set of third-order elastic constants for single crystals of NaF was determined from the hydrostatic-pressure and uniaxial-stress derivatives of natural sound velocities measured with a two-crystal ultrasonic-interference technique. There appeared to be no dislocation motion during the uniaxial measurements since changes in the natural sound velocities with stress were linear, and data recorded before and after a gamma

W. A. Bensch

1972-01-01

276

Two-frequency lidar technique for mesospheric Na temperature measurements  

Microsoft Academic Search

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

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

1990-01-01

277

NaCl-induced accelerated oxidation of a titanium alloy  

Microsoft Academic Search

The effect of a surface deposit of NaCl on the oxidation characteristics of a high-temperature titanium alloy was studied in the temperature range of 400600C. The influence of the water vapor content in the oxidizing environment was examined in the light of an existing electrochemical mechanism proposed for the hot-salt stress-corrosion-cracking phenomenon found in titanium alloys. It was established that

P. Dumas; C. St. John

1976-01-01

278

Na+ channel aggregation in remyelinating mouse sciatic axons following transection.  

PubMed

Mouse sciatic nerves from the degeneration-resistant strain C57BL/6/Wld (Ola) were surgically injected with lysolecithin to induce focal demyelination. Three days later they were transected adjacent to the spinal cord to eliminate contact of the axons with their cell bodies. The Na+ channel distribution was assessed by immunocytochemistry and followed at several stages of remyelination. Control experiments were performed on nerves that were injected but not cut. At (3 + 4) days, namely, nerves cut 3 days post-injection and examined 4 days after cutting, axons contained fully demyelinated regions. Na+ channel clusters appeared only at heminodes and at isolated sites that are likely to represent original nodes of Ranvier. During the next few days proliferating Schwann cells adhered to the axons and extended their processes. Clusters of Na+ channels appeared at their edges, and as the Schwann cells elongated the distance between these aggregates increased. A few clusters associated with neighboring Schwann cells approached each other and appeared to coalesce at sites where presumably new nodes of Ranvier would be formed. Beyond (3 + 6) days excessive degeneration of the transected axons precluded further observations. In the uncut controls, the spatio-temporal sequence of Schwann cell proliferation and channel patch formation and movement was similar to that described above, although myelin formation was somewhat faster than in the cut axons. It is concluded that Na+ channel aggregation associated with the early stages of remyelination is not dependent upon continuous communication of the axon with its cell body and is under local control. PMID:8567070

Tzoumaka, E E; Novakovi?, S D; Levinson, S R; Shrager, P

1995-10-01

279

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

280

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

E-print Network

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

Farritor, Shane

281

Factors influencing skeletal muscle Na+, K+-ATPase and Plasma [K+] during exercise in humans.  

E-print Network

??The sodium-potassium adenosine triphosphatase enzyme (Na+,K+ -ATPase) regulates muscle cell [Na+],[K+] and muscle membrane potential, therefore playing a fundamental role in muscle excitability. This dissertation (more)

Fraser, Steven Francis

2000-01-01

282

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

EPA Science Inventory

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

283

Subunit Dependence of Na Channel Slow Inactivation and Open Channel Block in Cerebellar Neurons  

E-print Network

inactivation, slow inactivation, and open-channel block, we recorded voltage-clamped, tetrodotoxin-sensitive Na firing depends on specialized voltage-gated channels. These include tetrodotoxin (TTX)- sensitive Na

Raman, Indira M.

284

Solvation of Na+, K+, and their dimers in helium.  

PubMed

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

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

2012-04-01

285

The local distribution of Na I interstellar gas  

NASA Technical Reports Server (NTRS)

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, Nu(sub ETA) = 2 x 10(exp 19) cm(exp -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.

1994-01-01

286

Xylanase recovery by ethanol and Na2SO4 precipitation.  

PubMed

Xylans are the major components of the hemicellulosic fraction of lignocellulosic biomass and their hydrolysis can be obtained using xylanases from Penicillium janthinellum. In this work, sugarcane bagasse hemicellulosic hydrolysate was used as the substrate for producing xylanase. The precipitation of these enzymes was studied using ethanol and Na2SO4 as precipitating agents. Ethanol precipitation experiments were performed batchwise in concentrations ranging from 10 to 80%, pH 4.0 to 7.0, at 4 degrees C. The concentrations used in the precipitations with Na2SO4 were from 5 to 60% at pH 5.5 and 25 degrees C. Solubility curves as a function of xylanase activity and total protein for both precipitating agents were made. According to the results, Na2SO4 is not appropriate for precipitating xylanases in this medium since at salt concentrations higher than 25%, the enzyme was denaturated and at this concentration less than 80% of the enzyme and total protein were precipitated. Because of differences in xylanase and total protein solubility, a fractionated precipitation using ethanol can be performed, since with 40% ethanol, 49% of the total protein was precipitated and more than 95% of the enzyme was kept in solution. On the other hand approx 100% of the xylanases were recovered by precipitation after adding 80% ethanol. PMID:18576030

Cortez, E V; Pessoa, A; Assis, A N

1998-01-01

287

Aldosterone Regulates Na,K-ATPase and Increases Lung Edema Clearance in Rats  

Microsoft Academic Search

Aldosterone increases the Na,K-ATPase function in renal cells involved in active Na 1 transport. Be- cause the alveolar type 2 (AT2) cells participate in active Na 1 transport, we studied whether aldoster- one regulates the Na,K-ATPase in rat AT2 cells and whether aldosterone delivered by aerosols to spontaneously breathing rats affects edema clearance in a model of isolated-perfused lungs. The

WALTER G. OLIVERA; DAVID E. CICCOLELLA; NORA BARQUIN; KAREN M. RIDGE; DAVID H. RUTSCHMAN; DONOVAN B. YEATES; JACOB I. SZNAJDER

2000-01-01

288

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

Microsoft Academic Search

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

ANA M. CORREA; RAMON LATORRE; FRANCISCO BEZANILLA

1991-01-01

289

The effect of NaCl on proline accumulation in rice leaves  

Microsoft Academic Search

The regulation of proline accumulation in detached leaves of rice(Oryza sativa cv. Taichung Native 1) was investigated.Increasing concentrations of NaCl from 50 to 200 mM progressivelyincreased proline content in detached rice leaves. NaCl induced prolineaccumulation was mainly due to the effect of both Na+ andCl- ions. Proline accumulation caused by NaCl was related toprotein proteolysis, an increase in ornithine-d-aminotransferaseactivity,a decrease

Chuan Chi Lin; Yi Ting Hsu; Ching Huei Kao

2002-01-01

290

Cryptosin induces backbone structural changes in cardiac Na+ and K+ dependent adenosinetriphosphatase.  

PubMed

Cryptosin, a new cardenolide, was found to preferentially bind to Na,K-ATPase enzyme (7), which is believed to be the ouabain binding site on cardiac sarcolemmal membrane. CD spectral studies revealed that cryptosin, in the presence of Na+ and Mg++ ions, bind to Na,K-ATPase and induce a dose-dependent change in the backbone structure of cardiac Na,K-ATPase. PMID:1965277

Venkateswara, R R; Dipak, D; Banning, J W; Vaidyanathan, C S

1990-10-01

291

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

292

Differential blockade of neuronal voltage-gated Na + and K + channels by antidepressant drugs  

Microsoft Academic Search

The effects of a range of antidepressants were investigated on neuronal voltage-gated Na+ and K+ channels. With the exception of phenelzine, all antidepressants inhibited batrachotoxin-stimulated 22Na+ uptake, most likely via negative allosteric inhibition of batrachotoxin binding to neurotoxin receptor site-2 on the Na+ channel. Imipramine also produced a differential action on macroscopic Na+ and K+ channel currents in acutely dissociated

Graham M Nicholson; Tim Blanche; Kylie Mansfield; Yvonne Tran

2002-01-01

293

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

NASA Astrophysics Data System (ADS)

The Na-rich part (~30% Na) of the Na-Au-Ga system between NaAu2, NaGa4, and Na22Ga39 has been found to contain the ternary phases Na8Au9.8(4)Ga7.2 (I) and Na17Au5.87(2)Ga46.63 (II), according to the results of single crystal X-ray diffraction measurements. I is orthorhombic, Cmcm, a=5.3040(1), b=24.519(5), c=14.573(3) , and contains a network of clusters with local 5-fold symmetry along the a-axis. Such clusters are frequent building units in decagonal quasicrystals and their approximants. II is rhombohedral, R3m, a=16.325(2), c=35.242(7) , and contains building blocks that are structurally identical to the Bergman-type clusters as well as fused icosahedral units known with active metals, triels and late transition elements. II also contains a polycationic network with elements of the clathrate V type structure. Tight-binding electronic structure calculations using linear muffin-tin-orbital (LMTO) methods on idealized models of I and II indicate that both compounds are metallic with evident pseudogaps at the corresponding Fermi levels. The overall Hamilton bond populations are generally dominated by Au-Ga and Au-Au bonds in I and by Ga-Ga bonds in II; moreover, the Na-Au and Na-Ga contributions in I are unexpectedly large, ~20% of the total. A similar involvement of sodium in covalent bonding has also been found in the electron-richer i-Na13Au12Ga15 quasicrystal approximant.

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

2013-11-01

294

Na+-transport modulation induces isoform-specific expression of Na+,K+ATPase ?-subunit isoforms in C2C12 skeletal muscle cell  

Microsoft Academic Search

Changes in demands for Na+ transport alter expression of the Na+,K+-ATPase subunit isoforms. In skeletal muscle, the effects of these changes on expression the a2 isoform, the major isoform expressed in differentiated muscle cell, is not known. Therefore, this study examines regulation of the a-subunit isoforms by Na+ in the C2C12 skeletal muscle cell that expresses the a1 and a2

Richard Ladka; Yuk-Chow Ng

2000-01-01

295

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

PubMed Central

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

2012-01-01

296

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

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

297

On the locus of action of Na + at site I of oxidative phosphorylation  

Microsoft Academic Search

The effect of octylguanidine on the Na+ stimulated oxygen uptake of rat liver mitochondria and bovine heart submitochondrial particles and on the Na+ induced efflux of K from the mitochondria has been examined. The results indicate that the action of Na+ is inhibited by octylguanidine, but that the degree of inhibition depends on the concentration of the cation. Apparently, a

A. Gmez-Puyou; F. Sandoval; M. Tuena De Gmez-Puyou; E. Chvez; E. Pinto

1972-01-01

298

Expression of Cardiac Na Channels with Appropriate Physiological and Pharmacological Properties in Xenopus Oocytes  

Microsoft Academic Search

The objective of this study was to determine whether the Xenopus laevis oocyte can express an exogenous cardiac Na channel that retains its normal physiological and pharmacological properties. Cardiac Na channels were expressed in oocytes following injection of RNA from guinea pig, rat, and human heart and detailed analysis was performed for guinea pig cardiac Na channels. Average current amplitudes

D. S. Krafte; W. A. Volberg; K. Dillon; A. M. Ezrin

1991-01-01

299

Glycosaminoglycan polymerization may enable osmotically inactive Na+ storage in the skin.  

PubMed

Osmotically inactive skin Na(+) storage is characterized by Na(+) accumulation without water accumulation in the skin. Negatively charged glycosaminoglycans (GAGs) may be important in skin Na(+) storage. We investigated changes in skin GAG content and key enzymes of GAG chain polymerization during osmotically inactive skin Na(+) storage. Female Sprague-Dawley rats were fed a 0.1% or 8% NaCl diet for 8 wk. Skin GAG content was measured by Western blot analysis. mRNA content of key dermatan sulfate polymerization enzymes was measured by real-time PCR. The Na(+) concentration in skin was determined by dry ashing. Skin Na(+) concentration during osmotically inactive Na(+) storage was 180-190 mmol/l. Increasing skin Na(+) coincided with increasing GAG content in cartilage and skin. Dietary NaCl loading coincided with increased chondroitin synthase mRNA content in the skin, whereas xylosyl transferase, biglycan, and decorin content were unchanged. We conclude that osmotically inactive skin Na(+) storage is an active process characterized by an increased GAG content in the reservoir tissue. Inhibition or disinhibition of GAG chain polymerization may regulate osmotically inactive Na(+) storage. PMID:14975935

Titze, Jens; Shakibaei, Mehdi; Schafflhuber, Markus; Schulze-Tanzil, Gundula; Porst, Markus; Schwind, Karl H; Dietsch, Peter; Hilgers, Karl F

2004-07-01

300

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

E-print Network

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

Chu, Xinzhao

301

Elevated levels of glucose and L-fucose reduce 22Na+ uptake and whole cell Na+ current in cultured neuroblastoma cells.  

PubMed

Na+ flux was studied in cultured neuroblastoma cells grown in medium containing increased glucose or L-fucose concentrations. Chronic exposure of neuroblastoma cells to 30 mM glucose or 30 mM L-fucose caused a decrease in ouabain-sensitive and veratridine-stimulated 22Na+ uptake compared with cells cultured in unsupplemented medium. The Na+ current, determined by using whole-cell configuration of the patch clamp, was also decreased in these cells. Tetrodotoxin (3 microM), which blocked whole cell Na+ currents, also blocked veratridine-stimulated 22Na+ accumulation. Culturing cells in medium containing 30 mM fructose as an osmotic control had no effect on Na+ flux. Specific [3H]saxitoxin binding was not affected by 30 mM glucose or 30 mM L-fucose compared with cells grown in unsupplemented medium, suggesting that the number of Na+ channels was not decreased. These studies suggest that exposing cultured neuronal cells to conditions that occur in the diabetic milieu alters Na+ transport and Na(+)-channel activity. PMID:8263545

Yorek, M A; Stefani, M R; Wachtel, R E

1994-01-01

302

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

SciTech Connect

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

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

1993-12-01

303

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 (41N, 105W) 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

304

Diffusion and the dynamics of displacive phase transitions in cryolite (Na 3 AlF 6 ) and chiolite (Na 5 Al 3 F 14 ): Multinuclear NMR studies  

Microsoft Academic Search

Cryolite is a mixed-cation perovskite (Na2(NaAl)F6) which undergoes a monoclinic to orthorhombic displacive phase transition at ~550 C. Chiolite (Na5Al3F14) is associated with cryolite in natural deposits, and consists of sheets of corner sharing [AlF6] octahedra interlayered with edge-sharing [NaF6] octahedra. Multi-nuclear NMR line shape and relaxation time (T1) studies were performed on cryolite and chiolite in order to gain

Dane R. Spearing; Jonathan F. Stebbins; Ian Farnan

1994-01-01

305

Reactivity of NASICON with water and interpretation of the detection limit of a NASICON based Na + ion selective electrode  

Microsoft Academic Search

The leaching of Na+ ions from NASICON of composition Na3Zr2Si2PO12 to the aqueous solution was evidenced. The origin of the Na+ leaching was studied using Na+ concentration and pH measurements as well as solution and X-ray analyses. The Na+ released was mainly attributed to the dissolution of a second phase, predominantly amorphous. The rate of Na+ release was found to

F. Mauvy; E. Siebert; P. Fabry

1999-01-01

306

Modeling the sorption dynamics of NaH using a reactive force field  

SciTech Connect

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

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

2008-04-28

307

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

308

In vitro, ethanol (ETOH) stimulates or inhibits Na/sup +/, K/sup +/-ATPase depending on Na/sup +//K/sup +/ ratios  

SciTech Connect

Effects of pharmacologically relevant levels of ETOH on porcine brain enzyme (PBE) and rat brain enzyme (RBE) were investigated. While varying Na/sup +/ and K/sup +/ levels, yet keeping their sum at 150mM, ETOH at 500mg/dL stimulated PBE when K/sup +/ > Na/sup +/ but inhibited when Na/sup +/ > K/sup +/. When Na/sup +//K/sup +/ = 15/90mM (intracellular conc.), ETOH stimulated PBE 48% but when Na/sup +//K/sup +/ = 144/6mM (extracellular conc.) ETOH inhibited 45%. For RBE, ETOH at 100, 300, and 450mg/dL stimulated 4%, 33%, and 20%, respectively, when Na/sup +//K/sup +/ = 15/88mM (intracellular) but inhibited 28%, 28%, and 25%, respectively, when Na/sup +//K/sup +/ = 142/4mM (extracellular). When Na/sup +/ is rate limiting, thus controlling enzyme activity from its high affinity site, ETOH is stimulatory but when K/sup +/ is rate limiting (controlling from its high affinity site) ETOH is inhibitory. These data could be explained by a tandem model for Na/sup +/ and K/sup +/ activation where ETOH promotes a shift from an intracellular to an extracellular facing conformation. Moreover, these data also strongly indicate that intoxicating levels of ETOH may affect the Na/sup +/, K/sup +/ -pump in vivo, especially in neurons which experience varying Na/sup +/ and K/sup +/ levels on each side of the cell membrane.

Foster, D.M.; Klemm, W.R.

1986-05-01

309

Temperature-Dependent Solubility Transition of Na2SO4 in Water and the Effect of NaCl Therein: Solution Structures and Salt Water Dynamics.  

PubMed

Dual, aqueous solubility behavior of Na2SO4 as a function of temperatures is still a natural enigma lying unresolved in the literature. The solubility of Na2SO4 increases up to 32.38 C and decreases slightly thereafter at higher temperatures. We have thrown light on this phenomenon by analyzing the Na2SO4-water clusters (growth and stability) detected from temperature-dependent dynamic light scattering experiments, solution compressibility changes derived from the density and speed of sound measurements, and water structural changes/Na2SO4 (ion pair)-water interactions observed from the FT-IR and 2D DOSY (1)H NMR spectroscopic investigations. It has been observed that Na2SO4-water clusters grow with an increase in Na2SO4 concentration (until the solubility transition temperature) and then start decreasing afterward. An unusual decrease in cluster size and solution compressibility has been observed with the rise in temperature for the Na2SO4 saturated solutions below the solubility transition temperature, whereas an inverse pattern is followed thereafter. DOSY experiments have indicated different types of water cluster species in saturated solutions at different temperatures with varying self-diffusion coefficients. The effect of NaCl (5-15 wt %) on the solubility behavior of Na2SO4 at different temperatures has also been examined. The studies are important from both fundamental and industrial application points of view, for example, toward the clean separation of NaCl and Na2SO4 from the effluent streams of textile and tannery industries. PMID:25313635

Bharmoria, Pankaj; Gehlot, Praveen Singh; Gupta, Hariom; Kumar, Arvind

2014-11-01

310

Inhibition and activation of Na/sup +/-Ca/sup 2 +/ exchange activity by quinacrine  

SciTech Connect

Quinacrine either inhibited or stimulated Na-Ca exchange in cardiac sarcolemmal vesicles, depending on the experimental conditions. When present in the assay medium for Na-Ca exchange, quinacrine inhibited both Na/sub i/-dependent Ca/sup 2 +/ uptake (K/sub i/ = 50 ..mu..M) and Na/sub 0/-dependent Ca/sup 2 +/ efflux. Quinacrine's inhibition of Ca/sub 2//sup +/ efflux was attenuated by high concentrations of Na/sup +/. Quinacrine also blocked Na-Na and Ca-Ca exchange activities in the vesicles. The inhibitory effects of quinacrine on Na-Ca exchange activity are qualitatively similar to those reported previously for amiloride derivatives. When Na-loaded vesicles were preincubated with quinacrine and then assayed for Na-Ca exchange in a quinacrine-free medium, stimulation of exchange activity was observed. This stimulation was reversible on the removal of bound quinacrine and involved a reduction in the apparent K/sub m/ for extravesicular Ca/sup 2 +/. Stimulation of exchange activity under these conditions was also observed with the lipophilic cations tetraphenylphosphonium. Since Ca/sup 2 +/, quinacrine and tetraphenylphosphonium all bind strongly to sarcolemmal membranes it is suggested that the observed stimulation of exchange activity involves a local electrostatic effect of the bound cations in accelerating a rate-limiting step in the reaction mechanism for Na-Ca exchange.

de la Pena, P.; Reeves, J.P.

1987-01-01

311

Reversible stimulation of the Na+/K+ pump by monensin in cultures of vascular smooth muscle.  

PubMed

Two ionophores, monensin and salinomycin, increased total cell Na+ and ouabain-sensitive 86Rb+ uptake in cultures of smooth muscle cells from rat aorta. Monensin was used to produce graded increases in cell Na+ in order to assess the Na+ dependence of the Na+/K+ pump in the intact cell. The relationship between internal Na+ and ouabain-sensitive 86Rb+ uptake was hyperbolic (K'Na = 3 mM). Monensin did not stimulate 86Rb+ uptake in the absence of external Na+. Loading the cells with Na+ by exposing cultures to a K+-free medium for 3 hr maximally increased cell Na+ and ouabain-sensitive 86Rb+ uptake to the same extent as monensin. Total cell Na+ and pump activity in monensin-treated cells returned to the initial values after removing the ionophore. Monensin was then able to increase total cell Na+ and ouabain-sensitive 86Rb+ uptake to the same extent as the initial treatment with the ionophore. PMID:7132555

Brock, T A; Smith, J B

1982-09-01

312

Composite PEOn:NaTFSI polymer electrolyte: Preparation, thermal andelectrochemical characterization  

NASA Astrophysics Data System (ADS)

Membranes of sodium bis(trifluoromethanesulfonate) imide (NaTFSI) complexed with poly(ethylene oxide) (PEO) salt have been prepared by a solvent-free hot-pressing technique with different EO:Na molar ratio. All membranes show good ionic conductivities in the range of 10-3Scm-1 above 70C. However, the more NaTFSI-concentrated samples are sticky gums due to the plasticizing nature of the anion. The PEO20:NaTFSI sample exhibits the compromise of conductivity, thermal and mechanical properties. The addition of nanometric SiO2 to the PEO20:NaTFSI membranes further enhances their mechanical properties. Moreover, the PEO20:NaTFSI+5wt.% SiO2 membranes show similar ionic conductivity and similar anodic electrochemical stability in comparison to the ceramic free PEO20:NaTFSI sample. In a Na(s)/polymer electrolyte/Na(s) symmetrical cell followed up to 30 days, the presence of the ceramic filler slightly increased the interface resistance in comparison to the ceramic-free membrane. Nuclear magnetic resonance determinations of anion diffusion coefficients and Na+ mobility suggest that presence of filler may have a positive affect on the cation transference number that is in accordance with the tNa+ transference number measurement.

Serra Moreno, J.; Armand, M.; Berman, M. B.; Greenbaum, S. G.; Scrosati, B.; Panero, S.

2014-02-01

313

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

PubMed

Influence of 100 mM NaCl and 50 microM salicylic acid (SA) and their combination on the metabolism of chamomile (Matricaria chamomilla) during 7 days was studied. NaCl reduced growth and selected physiological parameters and SA in combined treatment (NaCl + SA) reversed majority of these symptoms. Application of SA reduced NaCl-induced increase of Na+ in the rosettes, but not in the roots. Accumulation of total amino acids was stimulated in NaCl-treated roots, especially due to exceptional increase of proline (4.4-fold). Among phenolic acids, accumulation of protocatechuic acid was the most enhanced in NaCl-exposed leaf rosettes (ca. 3-fold) while chlorogenic and caffeic acids in the roots (2.4- and 2.8-fold, respectively). Total soluble phenols increased after NaCl and SA treatments, but root lignin content was not affected. Activity of phenylalanine ammonia-lyase and shikimate dehydrogenase increased in response to NaCl, but cinnamyl alcohol dehydrogenase was not affected and polyphenol oxidase decreased. Stress parameters were elevated by NaCl treatment (superoxide radical and malondialdehyde content, activities of catalase, ascorbate- and guaiacol-peroxidase) and substantially prevented by SA, while accumulation of hydrogen peroxide decreased. Overall, SA showed strong beneficial properties against NaCl-induced negative symptoms. Protective effect of SA was the most visible at the level of guaiacol-peroxidase and through amelioration of stress parameters and mineral nutrient contents. PMID:19381803

Kovcik, Jozef; Klejdus, Borivoj; Hedbavny, Josef; Backor, Martin

2009-07-01

314

Ca/Na montmorillonite: structure, forces and swelling properties.  

PubMed

Ca/Na montmorillonite and natural Wyoming bentonite (MX-80) have been studied experimentally and theoretically. For a clay system in equilibrium with pure water, Monte Carlo simulations predict a large swelling when the clay counterions are monovalent, while in presence of divalent counterions a limited swelling is obtained with an aqueous layer between the clay platelets of about 10 A. This latter result is in excellent agreement with X-ray scattering data, while dialysis experiments give a significantly larger swelling for Ca montmorillonite in pure water. Obviously, there is one "intra-lamellar" and a second "extra-lamellar" swelling. Montmorillonite in contact with a salt reservoir containing both Na(+) and Ca(2+) counterions will only show a modest swelling unless the Na(+) concentration in the bulk is several orders of magnitude larger than the Ca(2+) concentration. The limited swelling of clay in presence of divalent counterions is a consequence of ion-ion correlations, which reduce the entropic repulsion as well as give rise to an attractive component in the total osmotic pressure. Ion-ion correlations also favor divalent counterions in a situation with a competition with monovalent ones. A more fundamental result of ion-ion correlations is that the osmotic pressure as a function of clay sheet separation becomes nonmonotonic, which indicates the possibility of a phase separation into a concentrated and a dilute clay phase, which would correspond to the "extra-lamellar" swelling found in dialysis experiments. This idea also finds support in the X-ray scattering spectra, where sometimes two peaks corresponding to different lamellar spacings appear. PMID:20235552

Segad, M; Jnsson, Bo; Akesson, T; Cabane, B

2010-04-20

315

Excimer lasers for superhigh NA 193-nm lithography  

NASA Astrophysics Data System (ADS)

Excimer lasers are widely used as the light source for microlithography scanners. The volume shipment of scanner systems using 193nm is projected to begin in year 2003. Such tools will directly start with super high numerical aperture (NA) in order to take full advantage of the 193nm wavelength over the advanced 248nm systems. Reliable high repetition rate laser light sources enabling high illumination power and wafer throughput are one of the fundamental prerequisites. In addition these light sources must support a very high NA imaging lens of more than 0.8 which determines the output spectrum of the laser to be less than 0.30 pm FWHM. In this paper we report on our recent progress in the development of high repetition rate ultra-narrow band lasers for high NA 193nm microlithography scanners. The laser, NovaLine A4003, is based on a Single Oscillator Ultral Line-narrowed (SOUL) design which yields a bandwidth of less than 0.30pm FWHM. The SOUL laser enables superior optical performance without adding complexity or cost up to the 4 kHz maximum repetition rate. The A4003's high precision line-narrowing optics used in combination with the high repetition rate of 4 kHz yields an output power of 20 W at an extremely narrow spectral bandwidth of less than 0.30 pm FWHM and highest spectral purity of less than 0.75 pm for the 95% energy content. We present performance and reliability data and discuss the key laser parameters. Improvements in the laser-internal metrology and faster regulation control result in better energy stability and improved overall operation behavior. The design considerations for line narrowing and stable laser operation at high repetition rates are discussed.

Paetzel, Rainer; Albrecht, Hans S.; Lokai, Peter; Zschocke, Wolfgang; Schmidt, Thomas; Bragin, Igor; Schroeder, Thomas; Reusch, Christian; Spratte, Stefan

2003-06-01

316

Andrade's Milagre na Cela: Theatrical Space and Body Movement  

E-print Network

, Milagre na Cela (1978), presents a decisive shift in both theme and structure. In a work about the torture of a prisoner of con science in a setting which is at the same time both highly contemporary and imbued with mythical resonance, the traditional... coherent present. In Marta, a Arvore e o Relgio, a collection of ten plays written between 1951 and 1970, he develops several recurrent themes: the search for identity in the aftermath of the fall of the fazendeiro economy, the effects upon the human...

Unruh, Vicky

1981-10-01

317

Project ELaNa and NASA's CubeSat Initiative  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the NASA program to use expendable lift vehicles (ELVs) to launch nanosatellites for the purpose of enhancing educational research. The Education Launch of Nanosatellite (ELaNa) project, run out of the Launch Services Program is requesting proposals for CubeSat type payload to provide information that will aid or verify NASA Projects designs while providing opportunities for higher educational research. Some of the challenges involved with the program are discussed, and there is brief discussion about requirements for participation in the program, and the number of flight opportunities available for the launch of the Poly Picosatellite Orbital Deployer (PPOD).

Skrobot, Garrett Lee

2010-01-01

318

Polarizabilities of Li and Na in Debye plasmas  

SciTech Connect

We have carried out calculations to investigate the effect of Debye plasmas on the dipole, quadrupole, octupole polarizabilities of lithium and sodium atoms using the symplectic algorithm in the framework of the pseudo-state summation technique. The polarizabilities of alkali-metal atoms for various Debye lengths are reported for the first time in the literature. The behavior of the transition energies and oscillator strengths for Li and Na in plasma environments is also presented. In free atomic cases, our calculated results are in good agreement with the reported theoretical and experimental results.

Li, H. W. [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150080 (China); Kar, Sabyasachi [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China)

2012-07-15

319

Analysis of Cl and Na in Hyperimmune Sera by NAA  

NASA Astrophysics Data System (ADS)

The Cl and Na concentration values in four types of hyperimmune sera (anti-Bothrops, anti-Diphtheria, anti-Rabies and anti-Tetanus) used for immunological therapy were determined using Neutron Activation Analysis (NAA). These data were compatible with the specifications established by the Word Health Organization (WHO-OMS) and with the Brazilian Official Pharmacopea (Pharmaceutical Code Official of the Country). These data are an important support for quality control of hyperimmune sera production at Butantan Institute (So Paulo city, Brazil), responsible for supplying the Brazilian market.

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

2011-08-01

320

Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution  

PubMed Central

Desulfovibrio vulgaris Hildenborough strains with significantly increased tolerance to NaCl were obtained via experimental evolution. A NaCl-evolved strain, ES9-11, isolated from a population cultured for 1200 generations in medium amended with 100?mM NaCl, showed better tolerance to NaCl than a control strain, EC3-10, cultured for 1200 generations in parallel but without NaCl amendment in medium. To understand the NaCl adaptation mechanism in ES9-11, we analyzed the transcriptional, metabolite and phospholipid fatty acid (PLFA) profiles of strain ES9-11 with 0, 100- or 250?mM-added NaCl in medium compared with the ancestral strain and EC3-10 as controls. In all the culture conditions, increased expressions of genes involved in amino-acid synthesis and transport, energy production, cation efflux and decreased expression of flagellar assembly genes were detected in ES9-11. Consistently, increased abundances of organic solutes and decreased cell motility were observed in ES9-11. Glutamate appears to be the most important osmoprotectant in D. vulgaris under NaCl stress, whereas, other organic solutes such as glutamine, glycine and glycine betaine might contribute to NaCl tolerance under low NaCl concentration only. Unsaturation indices of PLFA significantly increased in ES9-11. Branched unsaturated PLFAs i17:1 ?9c, a17:1 ?9c and branched saturated i15:0 might have important roles in maintaining proper membrane fluidity under NaCl stress. Taken together, these data suggest that the accumulation of osmolytes, increased membrane fluidity, decreased cell motility and possibly an increased exclusion of Na+ contribute to increased NaCl tolerance in NaCl-evolved D. vulgaris. PMID:23575373

Zhou, Aifen; Baidoo, Edward; He, Zhili; Mukhopadhyay, Aindrila; Baumohl, Jason K; Benke, Peter; Joachimiak, Marcin P; Xie, Ming; Song, Rong; Arkin, Adam P; Hazen, Terry C; Keasling, Jay D; Wall, Judy D; Stahl, David A; Zhou, Jizhong

2013-01-01

321

Na,K-ATPase activity in mouse muscle is regulated by AMPK and PGC-1?.  

PubMed

Na,K-ATPase activity, which is crucial for skeletal muscle function, undergoes acute and long-term regulation in response to muscle activity. The aim of the present study was to test the hypothesis that AMP kinase (AMPK) and the transcriptional coactivator PGC-1? are underlying factors in long-term regulation of Na,K-ATPase isoform (?,? and PLM) abundance and Na(+) affinity. Repeated treatment of mice with the AMPK activator AICAR decreased total PLM protein content but increased PLM phosphorylation, whereas the number of ?- and ?-subunits remained unchanged. The K(m) for Na(+) stimulation of Na,K-ATPase was reduced (higher affinity) after AICAR treatment. PLM abundance was increased in AMPK kinase-dead mice compared with control mice, but PLM phosphorylation and Na,K-ATPase Na(+) affinity remained unchanged. Na,K-ATPase activity and subunit distribution were also measured in mice with different degrees of PGC-1? expression. Protein abundances of ?1 and ?2 were reduced in PGC-1? +/- and -/- mice, and the ?(1)/?(2) ratio was increased with PGC-1? overexpression (TG mice). PLM protein abundance was decreased in TG mice, but phosphorylation status was unchanged. Na,K-ATPase V (max) was decreased in PCG-1? TG and KO mice. Experimentally in vitro induced phosphorylation of PLM increased Na,K-ATPase Na(+) affinity, confirming that PLM phosphorylation is important for Na,K-ATPase function. In conclusion, both AMPK and PGC-1? regulate PLM abundance, AMPK regulates PLM phosphorylation and PGC-1? expression influences Na,K-ATPase ?(1) and ?(2) content and ?(1)/?(2) isoform ratio. Phosphorylation of the Na,K-ATPase subunit PLM is an important regulatory mechanism. PMID:21687978

Ingwersen, Maria S; Kristensen, Michael; Pilegaard, Henriette; Wojtaszewski, Jrgen F P; Richter, Erik A; Juel, Carsten

2011-07-01

322

An in vitro investigation of gastrointestinal Na(+) uptake mechanisms in freshwater rainbow trout.  

PubMed

In vitro gut-sac preparations of all four sections (stomach, anterior, mid, and posterior intestine) of the gastrointestinal tract (GIT) of freshwater rainbow trout, together with radiotracer ((22)Na) techniques, were used to study unidirectional Na(+) uptake rates (UR, mucosal?blood space) and net absorptive fluid transport rates (FTR) under isosmotic conditions (mucosal=serosal osmolality). On an area-specific basis, unidirectional Na(+) UR was highest in the mid-intestine, but when total gut area was taken into account, the three intestinal sections contributed equally, with very low rates in the stomach. The theoretical capacity for Na(+) uptake across the whole GIT is sufficient to supply all of the animal's nutritive requirements for Na(+). Transport occurs by low affinity systems with apparent K m values 2-3 orders of magnitude higher than those in the gills, in accord with comparably higher Na(+) concentrations in chyme versus fresh water. Fluid transport appeared to be Na(+)-dependent, such that treatments which altered unidirectional Na(+) UR generally altered FTR in a comparable fashion. Pharmacological trials (amiloride, EIPA, phenamil, bafilomycin, furosemide, hydrochlorothiazide) conducted at a mucosal Na(+) concentration of 50mmolL(-1) indicated that GIT Na(+) uptake occurs by a variety of apical mechanisms (NHE, Na(+) channel/H(+) ATPase, NCC, NKCC) with relative contributions varying among sections. However, at a mucosal Na(+) concentration of 10mmolL(-1), EIPA, phenamil, bafilomycin, and hydrochlorothiazide were no longer effective in inhibiting unidirectional Na(+) UR or FTR, suggesting the contribution of unidentified mechanisms under low Na(+) conditions. A preliminary model is presented. PMID:25183198

Nadella, Sunita R; Patel, Dhanisha; Ng, Allen; Wood, Chris M

2014-12-01

323

Hydrothermal crystallization of Na2Ti6O13, Na2Ti3O7, and Na16Ti10O28 in the NaOH-TiO2-H2O system at a temperature of 500C and a pressure of 0.1 GPa: The structural mechanism of self-assembly of titanates from suprapolyhedral clusters  

NASA Astrophysics Data System (ADS)

An increase in the NaOH concentration in the NaOH-TiO2 (rutile)-H2O system at a temperature of 500C and a pressure of 0.1 GPa leads to the crystallization R-TiO2 + Na2Ti6O13 ? Na2Ti3O7 ? Na16Ti10O28. Crystals of the Na2Ti6O13 titanate (space group C2/m) have the three-dimensional framework structure Ti6O13. The structure of the Na2Ti3O7 titanate (space group P2 1/ m) contains the two-dimensional layers Ti3O7. The structure of the Na16Ti10O28 titanate (space group P-1) is composed of the isolated ten-polyhedron cluster precursors Ti10O28. In all the structures, the titanium atoms have an octahedral coordination ( MTiO6). The matrix self-assembly of the Na2Ti6O13 and Na2Ti3O7 (Na4Ti6O14) crystal structures from Na4 M 12 invariant precursors is modeled. These precursors are clusters consisting of twelve M polyhedra linked through the edges. It is demonstrated that the structurally rigid precursors Na4 M 12 control all processes of the subsequent evolution of the crystal-forming titanate clusters. The specific features of the self-assembly of the Na2Ti3O7 structure that result from the additional incorporation of twice the number of sodium atoms into the composition of the high-level clusters are considered.

Hyushin, G. D.

2006-07-01

324

The inhibitory effect of hormones associated with stress on Na appetite of sheep.  

PubMed

Stress is a large stimulus of Na appetite in rabbits, rats, and mice. This study investigated the influence of some peptides implicated in stress, i.e., adrenocorticotropin (ACTH), corticotropin-releasing factor (CRF), and the recently discovered member of the CRF family, urocortin, on the ingestive behavior of sheep. Intracerebroventricular infusion of these peptides over 4 days decreased the need-free Na intake of Na-repleted sheep. Intracerebroventricular infusion of urocortin, however, did not alter Na intake of Na-depleted sheep. Systemic infusion of ACTH increased, whereas systemic infusion of either urocortin or CRF decreased, Na intake of Na-repleted sheep. The increase in Na intake caused by the peripheral infusion of ACTH was blocked by concurrent i.v. infusion of urocortin, substantiating the inhibitory role of this peptide on Na appetite. Central administration of all peptides and i.v. administration of urocortin or urocortin and ACTH combined decreased food intake. Water intake was not directly influenced by the peptides. Rather, decreased water intake, when observed, was secondary to decreased food intake, as determined by pair-feeding experiments. Whereas systemic infusion of ACTH mimics the increase in Na intake observed in several different stressful situations, CRF and urocortin actually inhibit Na intake, indicating a direct central action overriding any effect of these peptides on ACTH release. Indeed, the inhibition of Na intake by urocortin occurred despite its stimulation of ACTH release and the subsequent increase in peripheral level of cortisol. Thus it would appear that hormones associated with stress have both excitatory and inhibitory influences on Na intake. Presumably, other physiological processes entrained by stress also will be important in determining the quantitative outcome on Na appetite. PMID:10717005

Weisinger, R S; Blair-West, J R; Burns, P; Denton, D A; McKinley, M J; Purcell, B; Vale, W; Rivier, J; Sunagawa, K

2000-03-14

325

Na2Ni2TeO6: Evaluation as a cathode for sodium battery  

NASA Astrophysics Data System (ADS)

The sodium layered oxides Na2Ni2TeO6, Na2Co2TeO6 and Na1.6Sr0.2Ni2TeO6 have been synthesized by conventional solid-state method. The samples were characterized by X-ray diffractometry (XRD), cyclic voltammetry (CV), scanning electron microscopy (SEM) and charge-discharge measurements. The results show that all the samples crystallize in a hexagonal unit cell without impurity. The electrochemical Na+ extraction (i.e., the charge profile) for Na2Ni2TeO6 exhibits two voltage plateaus at 3.6 and 4.4 V, the first corresponds to Na+ ordering at extraction of 1/3 of the sodium ions per formula unit, the second to the onset of SEI formation. Detailed XPS analysis confirms that the Ni(III) does not disproportionate into Ni(III) and Ni(IV). The process of Na extraction/insertion in the interlayers of Na2Ni2TeO6 is highly reversible with a capacity of 100 mAh g-1 at slow cycling rate (0.03 C) in the 4.35 to 3 V voltage range versus Na+/Na. The lattice constant and the unit-cell volume increase with the substitution of Na+ by Sr2+. In the presence of Sr2+, the appearance of a step in the charge-discharge profile of Na1.6Sr0.2Ni2TeO6 is suppressed. Na2Co2TeO6 showed little Na extraction/insertion.

Gupta, Asha; Buddie Mullins, C.; Goodenough, John B.

2013-12-01

326

The gasotransmitter hydrogen sulphide decreases Na? transport across pulmonary epithelial cells.  

PubMed

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

Althaus, M; Urness, K D; Clauss, W G; Baines, D L; Fronius, M

2012-07-01

327

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

PubMed Central

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

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

2012-01-01

328

Quantification of Na+,K+ pumps and their transport rate in skeletal muscle: functional significance.  

PubMed

During excitation, muscle cells gain Na(+) and lose K(+), leading to a rise in extracellular K(+) ([K(+)]o), depolarization, and loss of excitability. Recent studies support the idea that these events are important causes of muscle fatigue and that full use of the Na(+),K(+)-ATPase (also known as the Na(+),K(+) pump) is often essential for adequate clearance of extracellular K(+). As a result of their electrogenic action, Na(+),K(+) pumps also help reverse depolarization arising during excitation, hyperkalemia, and anoxia, or from cell damage resulting from exercise, rhabdomyolysis, or muscle diseases. The ability to evaluate Na(+),K(+)-pump function and the capacity of the Na(+),K(+) pumps to fill these needs require quantification of the total content of Na(+),K(+) pumps in skeletal muscle. Inhibition of Na(+),K(+)-pump activity, or a decrease in their content, reduces muscle contractility. Conversely, stimulation of the Na(+),K(+)-pump transport rate or increasing the content of Na(+),K(+) pumps enhances muscle excitability and contractility. Measurements of [(3)H]ouabain binding to skeletal muscle in vivo or in vitro have enabled the reproducible quantification of the total content of Na(+),K(+) pumps in molar units in various animal species, and in both healthy people and individuals with various diseases. In contrast, measurements of 3-O-methylfluorescein phosphatase activity associated with the Na(+),K(+)-ATPase may show inconsistent results. Measurements of Na(+) and K(+) fluxes in intact isolated muscles show that, after Na(+) loading or intense excitation, all the Na(+),K(+) pumps are functional, allowing calculation of the maximum Na(+),K(+)-pumping capacity, expressed in molar units/g muscle/min. The activity and content of Na(+),K(+) pumps are regulated by exercise, inactivity, K(+) deficiency, fasting, age, and several hormones and pharmaceuticals. Studies on the ?-subunit isoforms of the Na(+),K(+)-ATPase have detected a relative increase in their number in response to exercise and the glucocorticoid dexamethasone but have not involved their quantification in molar units. Determination of ATPase activity in homogenates and plasma membranes obtained from muscle has shown ouabain-suppressible stimulatory effects of Na(+) and K(+). PMID:24081980

Clausen, Torben

2013-10-01

329

Quantification of Na+,K+ pumps and their transport rate in skeletal muscle: Functional significance  

PubMed Central

During excitation, muscle cells gain Na+ and lose K+, leading to a rise in extracellular K+ ([K+]o), depolarization, and loss of excitability. Recent studies support the idea that these events are important causes of muscle fatigue and that full use of the Na+,K+-ATPase (also known as the Na+,K+ pump) is often essential for adequate clearance of extracellular K+. As a result of their electrogenic action, Na+,K+ pumps also help reverse depolarization arising during excitation, hyperkalemia, and anoxia, or from cell damage resulting from exercise, rhabdomyolysis, or muscle diseases. The ability to evaluate Na+,K+-pump function and the capacity of the Na+,K+ pumps to fill these needs require quantification of the total content of Na+,K+ pumps in skeletal muscle. Inhibition of Na+,K+-pump activity, or a decrease in their content, reduces muscle contractility. Conversely, stimulation of the Na+,K+-pump transport rate or increasing the content of Na+,K+ pumps enhances muscle excitability and contractility. Measurements of [3H]ouabain binding to skeletal muscle in vivo or in vitro have enabled the reproducible quantification of the total content of Na+,K+ pumps in molar units in various animal species, and in both healthy people and individuals with various diseases. In contrast, measurements of 3-O-methylfluorescein phosphatase activity associated with the Na+,K+-ATPase may show inconsistent results. Measurements of Na+ and K+ fluxes in intact isolated muscles show that, after Na+ loading or intense excitation, all the Na+,K+ pumps are functional, allowing calculation of the maximum Na+,K+-pumping capacity, expressed in molar units/g muscle/min. The activity and content of Na+,K+ pumps are regulated by exercise, inactivity, K+ deficiency, fasting, age, and several hormones and pharmaceuticals. Studies on the ?-subunit isoforms of the Na+,K+-ATPase have detected a relative increase in their number in response to exercise and the glucocorticoid dexamethasone but have not involved their quantification in molar units. Determination of ATPase activity in homogenates and plasma membranes obtained from muscle has shown ouabain-suppressible stimulatory effects of Na+ and K+. PMID:24081980

2013-01-01

330

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

PubMed

Hypertonic NaCl solutions have been used for small-volume resuscitation from hypovolemic shock. We sought to identify osmolality- and Na(+)-dependent components of the effects of the hyperosmotic NaCl solution (85 mOsm/kg increment) on contraction and cytosolic Ca(2+) concentration ([Ca(2+)](i)) in isolated rat ventricular myocytes. The biphasic change in contraction and Ca(2+) transient amplitude (decrease followed by recovery) was accompanied by qualitatively similar changes in sarcoplasmic reticulum (SR) Ca(2+) content and fractional release and was mimicked by isosmotic, equimolar increase in extracellular [Na(+)] ([Na(+)](o)). Raising osmolality with sucrose, however, augmented systolic [Ca(2+)](i) monotonically without change in SR parameters and markedly decreased contraction amplitude and diastolic cell length. Functional SR inhibition with thapsigargin abolished hyperosmolality effects on [Ca(2+)](i). After 15-min perfusion, both hyperosmotic solutions slowed mechanical relaxation during twitches and [Ca(2+)](i) decline during caffeine-evoked transients, raised diastolic and systolic [Ca(2+)](i), and depressed systolic contractile activity. These effects were greater with sucrose solution, and were not observed after isosmotic [Na(+)](o) increase. We conclude that under the present experimental conditions, transmembrane Na(+) redistribution apparently plays an important role in determining changes in SR Ca(2+) mobilization, which markedly affect contractile response to hyperosmotic NaCl solutions and attenuate the osmotically induced depression of contractile activity. PMID:17680266

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

2008-01-01

331

Uptake and Loss of Na+, Rb+, and Cs+ in Relation to an Active Mechanism for Extrusion of Na+ in Scenedesmus 1  

PubMed Central

The mechanism for extrusion of Na+ from Scenedesmus cells is characterized physiologically. It is stimulated by phosphate but oxygen is not necessary. Rb+ and Cs+ may also be extruded, but in the presence of Na+ they cannot compete for the sites on the inside of the transport system. When Na+ is extruded, Rb+ and, by inference, K+ seems to be transported as counter ion from the outside, and sodium ions compete only weakly for this external site. The parallelism between these findings and the Na+-K+-activated adenosine triphosphatases known from animal tissues is pointed out. With low additions of phosphate, the extrusion mechanism can keep the cells practically free from Na+. Increasing the concentrations of external phosphate stimulates uptake more than extrusion, and a net uptake occurs. As for Rb+ and Cs+, they are taken up in the absence of external phosphate, but additions of P will greatly enhance the amounts absorbed. Two different ways of uptake are indicated. PMID:5932402

Kylin, Anders

1966-01-01

332

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

PubMed

Na-ion batteries are gaining an increased recognition as the next generation low cost energy storage devices. Here, we present a characterization of Na3FePO4CO3 nanoplates as a novel cathode material for sodium ion batteries. First-principles calculations reveal that there are two paths for Na ion migration along b and c axis. In-situ and ex-situ Fe K-edge X-ray absorption near edge structure (XANES) point out that in Na3FePO4CO3 both Fe(2+)/Fe(3+) and Fe(3+)/Fe(4+) redox couples are electrochemically active, suggesting also the existence of a two-electron intercalation reaction. Ex-situ X-ray powder diffraction data demonstrates that the crystalline structure of Na3FePO4CO3 remains stable during the charging/discharging process within the range 2.0-4.55?V. PMID:24595232

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

2014-01-01

333

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

PubMed

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

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

2014-02-01

334

Properties of Na2SiF6:Mn4+ and Na2GeF6:Mn4+ red phosphors synthesized by wet chemical etching  

NASA Astrophysics Data System (ADS)

We report a simple method of synthesizing red phosphors, Na2SiF6:Mn4+ and Na2GeF6:Mn4+, by wet chemical etching of Si wafers and Ge shots in aqueous HF solution with the addition of an oxidizing agent NaMnO4. The x-ray diffraction analysis suggests that the red phosphors have the trigonal structure (space group=D32-P321). The optical properties of these phosphors are investigated using photoluminescence, photoluminescence excitation, optical absorption, and diffuse reflectance spectroscopy. The spectral features show no clear difference between Na2SiF6:Mn4+ and Na2GeF6:Mn4+ phosphors. They are well explained by the Tanabe-Sugano energy-level diagram with the crystal-field and Racah parameters of Dq 1970 cm-1, B 775 cm-1, and C 3490 cm-1 with C /B4.5.

Xu, Yan Kai; Adachi, Sadao

2009-01-01

335

Covering surface nanobubbles with a NaCl nanoblanket.  

PubMed

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

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

2013-09-10

336

First results and future perspectives of the NA60 experiment  

NASA Astrophysics Data System (ADS)

The NA60 experiment at the CERN SPS studies the production of open charm and prompt dimuons in collisions induced by proton and heavy ion beams on nuclear targets. The experimental setup includes a silicon vertex telescope, placed inside a dipole magnetic field, to match charged particle tracks with the muon tracks measured by a muon spectrometer. In p-A collisions the vertex telescope is mostly made of silicon microstrip planes, whereas in A-A interactions the higher multiplicity imposes the use of high granularity silicon pixel detectors. The high interaction rate required for the study of rare processes imposes the use of radiation tolerant pixel detectors. NA60 took its first data in the year 2002, with 400 GeV protons and with Pb ions of 20 and 30 GeV per nucleon. The proton data have been used for the study of dimuon production, while the heavy ion data were devoted to the commissioning of the pixel detectors and to the study of charged particle pseudorapidity densities. After an overview of the detector concept, this paper presents the first results obtained with the 2002 data.

Oppedisano, C.; NA60 Collaboration; Arnaldi, R.; Banicz, K.; Borer, K.; Buytaert, J.; Castor, J.; Chaurand, B.; Chen, W.; Cheynis, B.; Cicalo, C.; Colla, A.; Cortese, P.; David, A.; de Falco, A.; de Marco, N.; Devaux, A.; Drees, A.; Ducroux, L.; En'yo, H.; Ferretti, A.; Floris, M.; Force, P.; Grigorian, A.; Grossiord, J.-Y.; Guettet, N.; Guichard, A.; Gulkanian, H.; Heuser, J.; Keil, M.; Kluberg, L.; Li, Z.; Loureno, C.; Lozano, J.; Manso, F.; Masoni, A.; Neves, A.; Ohnishi, H.; Puddu, G.; Radermacher, E.; Rosinsky, P.; Scomparin, E.; Seixas, J.; Serci, S.; Shahoyan, R.; Sonderegger, P.; Usai, G.; Vardanyan, H.; Whri, H.

2004-01-01

337

Radiation-induced creep of confined NaCI  

NASA Astrophysics Data System (ADS)

Samples of pure single crystals of NaC1 and of a natural rock salt were simultaneously gamma-irradiated at an approximate constant dose rate (15 kGy/h) and a constant temperature (100C) and for different lengths of time, resulting in integrated doses ranging from 0.02 to 44.6 MGy. Microstructural analysis showed that both incipient deformation structures and very advanced recovery structures develop during irradiation. This shows that gamma-irradiation does not only cause dislocations to develop, but also to migrate and interfere. It is also shown that Na-colloids do not only develop attached to dislocations, but migrate, accumulate and annihilate together with them. Microstructural criteria are established to distinguish between three different types of colloid-depleted areas that develop with increasing irradition: a) bleached areas produced by dislocation rearrangement and migration; b) bleached areas produced by diffusion along the dislocation rearrangements; and c) (in polycrystals) white areas produced by migration of wet (brine containing) high-angle boundaries.

Celma, A. Garca; Donker, H.

1994-11-01

338

Tolerance of soil flagellates to increased NaCl levels.  

PubMed

The ability of heterotrophic flagellates to survive and adapt to increasing salinities was investigated in this study. Whole soil samples were subjected to salinities corresponding to marine conditions and clonal cultures were used to perform growth and adaptation experiments at a wide range of different salinities (0-50 ppm). More morphotypes tolerant to elevated NaCl levels were found in road verge soil that was heavily exposed to de-icing salt than in less exposed soils, though there were fewer tolerant than intolerant morphotypes in all soils examined. Heterotrophic flagellates isolated on a freshwater medium from a non-exposed soil were unable to thrive at salinities above 15 ppt, and showed reduced growth rates even at low salt salinities (1-5 ppt). The findings suggest that heterotrophic soil flagellates are less tolerant to NaCl than their aquatic relatives, possibly due to their long evolutionary history in soil, and support the idea that identical morphospecies may differ considerably with respect to physiology PMID:12188223

Ekelund, Flemming

2002-01-01

339

Iron oxide nanoparticles in NaA zeolite cages  

NASA Astrophysics Data System (ADS)

Zeolite NaA samples with varying concentration of Fe3+ ions have been prepared by wet chemical method. Based on powder X-ray diffraction, 29Si and 27Al MAS NMR and Fe3+ EPR investigations, the formation of nano-sized ferric oxide particles inside the larger ?-cages of zeolite NaA has been established. Both Mssbauer effect and magnetization measurements carried out down to 4.5 K established the superparamagnetic behaviour of these Fe2O3 particles with a blocking temperature of ?20 K, where the magnetization values showed deviation for the zero field cooled and field cooled samples and the appearance of a very narrow magnetic hysteresis loop below this temperature. For all Fe3+ containing samples the room temperature Mssbauer spectrum is a broad quadrupole doublet with chemical shift, ? ? 0.33 mm/s and quadrupole splitting, ?Eq ? 0.68 mm/s. Variable temperature 57Fe Mssbauer effect measurements exhibited magnetic features below the blocking temperature and at 4.5 K, the observed spectrum is a broad magnetic sextet characterized by an internal hyperfine field value of ?504 kOe along with a very weak central superparamagnetic quadrupole doublet.

Kulshreshtha, S. K.; Vijayalakshmi, R.; Sudarsan, V.; Salunke, H. G.; Bhargava, S. C.

2013-07-01

340

Mask-induced polarization effects at high NA  

NASA Astrophysics Data System (ADS)

It is important to understand how a photomask will polarize incident radiation. This paper presents data collected on binary mask and various attenuated phase shifting mask materials, feature sizes, duty ratios, and illumination schemes via rigorous coupled wave analysis, extinction spectroscopy, and 193nm lithographic evaluation. Additionally, the result of polarization effects due to the photomask on imaging has been studied. It was found that in the majority of the cases, higher NA led to greater polarization effects. All mask materials predominantly pass the TM polarization state for the 0 order, whereas different materials and duty ratios affect the polarization of the first diffracted orders differently. The polarization effects contributed by mask materials being considered for use in high NA imaging systems need to be examined. The degree of polarization as a function of n and k is presented, providing an introduction to the desirable properties of future mask materials. Materials with higher refractive indices and lower extinction coefficients tend to pass more of the TM polarization state, which is undesirable. Materials with lower indices and relatively wide range of extinction coefficients pass more TE polarized radiation. The duty ratio, critical dimension, mask material, material thickness, and illumination scheme all influence mask induced polarization effects.

Estroff, Andrew; Fan, Yongfa; Bourov, Anatoly; Smith, Bruce; Foubert, Philippe; Leunissen, L. H. A.; Philipsen, Vicky; Aksenov, Yuri

2005-05-01

341

Coulomb excitation of the proton-dripline nucleus Na20  

NASA Astrophysics Data System (ADS)

The low-energy structure of the proton dripline nucleus Na20 has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV/nucleon Na20 beam of ~5106 ions/s was Coulomb excited by a 0.5-mg/cm2natTi target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while ? rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2+ ground state to the first excited 3+ and 4+ states was observed, and B(?L) values were determined using the 2+?0+ de-excitation in Ti48 as a reference. The resulting B(?L)? values are B(E2;3+?2+)=556e2fm4 (17.01.9 W.u.), B(E2;4+?2+)=35.75.7e2fm4 (11.11.8 W.u.), and B(M1;4+?3+)=0.1540.030?N2 (0.0860.017 W.u.). These measurements provide the first experimental determination of B(?L) values for this proton dripline nucleus of astrophysical interest.

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

2009-10-01

342

Tetrodotoxin Sensitivity of the Vertebrate Cardiac Na+ Current  

PubMed Central

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

Vornanen, Matti; Hassinen, Minna; Haverinen, Jaakko

2011-01-01

343

Purinergic activation of rat skeletal muscle membranes increases Vmax and Na+ affinity of the Na,K-ATPase and phosphorylates phospholemman and ?1 subunits.  

PubMed

Muscle activity is associated with an increase in extracellular purines (ATP, ADP), which are involved in signalling mechanisms. The present study investigates the effect of purines on the function of Na,K-ATPase (Na,K-pump) in rat skeletal muscle. Na,K-ATPase activity was quantified by measuring the release of inorganic phosphate in the presence of ATP and variable Na(+) concentrations. In membranes purified from glycolytic muscle fibres, purinergic stimulation increases V (max) and decreases the K (m) (higher Na(+) affinity) of the Na,K-ATPase. Stimulatory effects were obtained using ATP, ADP, 2-methylthio-ADP and UPT, but not UDP and adenosine. The effect of ADP on V (max) can be inhibited by the non-specific P2Y receptor antagonists, suramin and PPADS. Moreover, the P2Y(13) receptor antagonist MRS 2211 strongly inhibited the response to ADP, whereas the specific P2Y(1) receptor antagonist MRS 2500 had less effect. Based on results from these agonists and antagonists, we conclude that P2Y(13) receptors mediate the main effects observed, that P2Y1 receptors are also involved and that some P2Y(2)/P2Y(4) receptors also appear to be involved. Receptor antagonists had no effect on ADP-induced subunit (phospholemman and ?1) phosphorylation and changes in K (m) (Na(+) affinity). Thus, the stimulatory effects of purines are mediated by two independent mechanisms: P2Y receptor-mediated increase in Na,K-ATPase capacity (increased V (max)) and P2Y receptor-independent phosphorylation of Na,K-ATPase phospholemman and ?1 subunits, which induce changes in ion affinity. These mechanisms may contribute to up-regulation of Na,K-ATPase during muscle activity. PMID:22057585

Walas, Helle; Juel, Carsten

2012-02-01

344

Na-doped hydroxyapatite coating on carbon/carbon composites: Preparation, in vitro bioactivity and biocompatibility  

NASA Astrophysics Data System (ADS)

Na-doped hydroxyapatite (Na-HA) coating was directly prepared onto carbon/carbon (C/C) composites using electrochemical deposition (ECD) and the mean thickness of the coating is approximately 10 2 ?m. The formed Na-HA crystals which are Ca-deficient, are rod-like with a hexagonal cross section. The Na/P molar ratios of the coating formed on C/C substrate is 0.097. During the deposition, the Na-HA crystals grow in both radial and longitudinal directions, and faster along the longitudinal direction. The pattern formation of crystal growth leads to dense coating which would help to increase the bonding strength of the coating. The average shear bonding strength of Na-HA coating on C/C is 5.55 0.77 MPa. The in vitro bioactivity of the Na-HA coated C/C composites were investigated by soaking the samples in a simulated body fluid (SBF) for 14 days. The results indicate that the Na-HA coated C/C composites can rapidly induce bone-like apatite nucleation and growth on its surface in SBF. The in vitro cellular biocompatibility tests reveal that the Na-HA coating was better to improve the in vitro biocompatibility of C/C composites compared with hydroxyapatite (HA) coating. It was suggested that the Na-HA coating might be an effective method to improve the surface bioactivity and biocompatibility of C/C composites.

Li, Hejun; Zhao, Xueni; Cao, Sheng; Li, Kezhi; Chen, Mengdi; Xu, Zhanwei; Lu, Jinhua; Zhang, Leilei

2012-12-01

345

Morphological, physiological, and structural responses of two species of artemisia to NaCl stress.  

PubMed

Effects of salt stress on Artemisia scoparia and A. vulgaris "Variegate" were examined. A. scoparia leaves became withered under NaCl treatment, whereas A. vulgaris "Variegate" leaves were not remarkably affected. Chlorophyll content decreased in both species, with a higher reduction in A. scoparia. Contents of proline, MDA, soluble carbohydrate, and Na(+) increased in both species under salt stress, but A. vulgaris "Variegate" had higher level of proline and soluble carbohydrate and lower level of MDA and Na(+). The ratios of K(+)/Na(+), Ca(2+)/Na(+), and Mg(2+)/Na(+) in A. vulgaris "Variegate" under NaCl stress were higher. Moreover, A. vulgaris "Variegate" had higher transport selectivity of K(+)/Na(+) from root to stem, stem to middle mature leaves, and upper newly developed leaves than A. scoparia under NaCl stress. A. vulgaris "Variegate" chloroplast maintained its morphological integrity under NaCl stress, whereas A. scoparia chloroplast lost integrity. The results indicated that A. scoparia is more sensitive to salt stress than A. vulgaris "Variegate." Salt tolerance is mainly related to the ability of regulating osmotic pressure through the accumulation of soluble carbohydrates and proline, and the gradient distribution of K(+) between roots and leaves was also contributed to osmotic pressure adjustment and improvement of plant salt tolerance. PMID:24235883

Guan, Zhi-Yong; Su, Yi-Ji; Teng, Nian-Jun; Chen, Su-Mei; Sun, Hai-Nan; Li, Chu-Ling; Chen, Fa-Di

2013-01-01

346

ANG-2 for quantitative Na(+) determination in living cells by time-resolved fluorescence microscopy.  

PubMed

Sodium ions (Na(+)) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na(+) concentrations ([Na(+)]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na(+)-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na(+)-sensitivity appropriate for recordings in living cells. The Na(+)-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na(+)]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na(+)]i rise in cockroach salivary gland cells, which was dependent on a Na(+)-K(+)-2Cl(-) cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems. PMID:25311309

Roder, Phillip; Hille, Carsten

2014-12-12

347

Cell Degradation of a Na-NiCl2 (ZEBRA) Battery  

SciTech Connect

In this work, the parameters influencing the degradation of a Na-NiCl2 (ZEBRA) battery were investigated. Planar Na-NiCl2 cells using ?-alumina solid electrolyte (BASE) were tested with different C-rates, Ni/NaCl ratios, and capacity windows, in order to identify the key parameters for the degradation of Na-NiCl2 battery. The morphology of NaCl and Ni particles were extensively investigated after 60 cycles under various test conditions using a scanning electron microscope. A strong correlation between the particle size (NaCl and Ni) and battery degradation was observed in this work. Even though the growth of both Ni and NaCl can influence the cell degradation, our results indicate that the growth of NaCl is a dominant factor in cell degradation. The use of excess Ni seems to play a role in tolerating the negative effects of particle growth on degradation since the available active surface area of Ni particles can be still sufficient even after particle growth. For NaCl, a large cycling window was the most significant factor, of which effects were amplified with decrease in Ni/NaCl ratio.

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.

2013-11-01

348

Mechanism of Na+/H+ exchange by Escherichia coli NhaA in reconstituted proteoliposomes.  

PubMed

Purified NhaA, a Na+/H+ antiporter from Escherichia coli, reconstituted into proteoliposomes was used to study partial reactions catalyzed by this protein. Homologous Na+/Na+ exchange as well as Na+/Li+ exchange via NhaA were detected by monitoring the effects of external Li+ and Na+ ions on the delta pH-driven sodium uptake into NH4 Cl-loaded vesicles. Furthermore, a sodium counterflow reaction was demonstrated in proteoliposomes preloaded with non-radioactive Na+ and placed into the experimental buffer containing low amounts of 22Na+ under experimental conditions when both components of protonmotive force generated by the antiporter. delta psi and delta pH, were dissipated by corresponding ionophores. The apparent Km for sodium counterflow is 1.1 mM, and Vmax is 80 mumol/min/mg of protein. External Na+ accelerates the downhill efflux of 22Na+ suggesting that the translocation of the Na(+)-loaded form of the carrier is faster than the rest of the catalytic cycle. PMID:8282121

Dibrov, P A; Taglicht, D

1993-12-28

349

High sodium ion conductivity of glass-ceramic electrolytes with cubic Na3PS4  

NASA Astrophysics Data System (ADS)

Sulfide solid electrolytes with cubic Na3PS4 phase has relatively high sodium ion conductivity of over 10-4Scm-1 at room temperature, and all-solid-state sodium batteries Na-Sn/TiS2 with the electrolyte operated as a secondary battery at room temperature. To improve battery performance, conductivity enhancement of sulfide electrolytes is important. In this study, we have succeeded in enhancing conductivity by optimizing preparation conditions of Na3PS4 glass-ceramic electrolytes. By use of crystalline Na2S with high purity of 99.1%, cubic Na3PS4 crystals were directly precipitated by ball milling process at the composition of 75Na2S25P2S5 (mol%). The glass-ceramic electrolyte prepared by milling for 1.5h and consecutive heat treatment at 270C for 1h showed the highest conductivity of 4.6נ10-4Scm-1, which is twice as high as the conductivity of the cubic Na3PS4 glass-ceramic prepared in a previous report. All-solid-state Na-Sn/NaCrO2 cells with the newly prepared electrolyte exhibited charge-discharge cycles at room temperature and kept about 60mAh per gram of NaCrO2 for 15 cycles.

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

2014-07-01

350

Nonselective Conduction in a Mutated NaK Channel with Three Cation-Binding Sites  

PubMed Central

The NaK channel is a cation-selective protein with similar permeability for K+ and Na+ ions. Crystallographic structures are available for the wild-type and mutated NaK channels with different numbers of cation-binding sites. We have performed a comparison between the potentials of mean force governing the translocation of K+ ions and mixtures of one Na+ and three K+ ions in a mutated NaK channel with only three cation-binding sites (NaK-CNG). Since NaK-CNG is not selective for K+ over Na+, analysis of its multi-ion potential energy surfaces can provide clues about how selectivity originates. Comparison of the potentials of mean force of NaK-CNG and K+-selective channels yields observations that strongly suggest that the number of contiguous ion binding sites in a single-file mechanism is the key determinant of the channels selectivity properties, as already proposed by experimental studies. We conclude that the presence of four binding sites in K+-selective channels is essential for highly selective and efficient permeation of K+ ions, and that a key difference between K+-selective and nonselective channels is the absence/presence of a binding site for Na+ ions at the boundary between S2 and S3 in the context of multi-ion permeation events. PMID:23200044

Furini, Simone; Domene, Carmen

2012-01-01

351

Gill microsomal (Na+,K+)-ATPase from the blue crab Callinectes danae: Interactions at cationic sites.  

PubMed

Euryhaline crustaceans tolerate exposure to a wide range of dilute media, using compensatory, ion regulatory mechanisms. However, data on molecular interactions occurring at cationic sites on the crustacean gill (Na+,K+)-ATPase, a key enzyme in this hyperosmoregulatory process, are unavailable. We report that Na+ binding at the activating site leads to cooperative, heterotropic interactions that are insensitive to K+. The binding of K+ ions to their high affinity sites displaces Na+ ions from their sites. The increase in Na+ ion concentrations increases heterotropic interactions with the K+ ions, with no changes in K0.5 for K+ ion activation at the extracellular sites. Differently from mammalian (Na+,K+)-ATPases, that from C. danae exhibits additional NH4+ ion binding sites that synergistically activate the enzyme at saturating concentrations of Na+ and K+ ions. NH4+ binding is cooperative, and heterotropic NH4+ ion interactions are insensitive to Na+ ions, but Na+ ions displace NH4+ ions from their sites. NH4+ ions also displace Na+ ions from their sites. Mg2+ ions modulate enzyme stimulation by NH4+ ions, displacing NH4+ ion from its sites. These interactions may modulate NH4+ ion excretion and Na+ ion uptake by the gill epithelium in euryhaline crustaceans that confront hyposmotic media. PMID:16055367

Masui, D C; Furriel, R P M; Silva, E C C; Mantelatto, F L M; McNamara, J C; Barrabin, H; Scofano, H M; Fontes, C F L; Leone, F A

2005-12-01

352

Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells  

PubMed Central

This paper describes the kinetics and stoichiometry of a tightly coupled Na-Li exchange transport system in human red cells. The system is inhibited by phloretin and furosemide but not by ouabain. Li influx by this system increases and saturates with increasing concentrations of external Li and internal Na and is inhibited competitively by external Na. Comparable functions relate Li efflux and Na efflux to internal and external Li and Na concentrations. Analysis of these relations yields the following values for the ion concentrations required to half-maximally activate the transport system: internal Na and Li 9.0 and 0.5 mM, respectively, external Na and Li 25 and 1.5 mM, respectively. The system performs a 1:1 exchange of Na and Li moving in opposite directions across the red cell membrane. We found no evidence for a simultaneous transport of more than one Na and Li by the system. The maximum transport rate of Na-dependent Li transport varied between 0.1 and 0.37 mmol/(liter of cells X h) in the red cells of the five normal male subjects studied. No significant variations between individual subjects were observed for bicarbonate-stimulated Li transport and for the residual Li fluxes which occur in the absence of bicarbonate and in the presence of ouabain plus phloretin. PMID:690598

1978-01-01

353

NaOH-modified ceramic honeycomb with enhanced formaldehyde adsorption and removal performance.  

PubMed

NaOH-modified ceramic honeycombs (Na-CH) were simply prepared by impregnating ceramic honeycombs (CH) into NaOH aqueous solution. It was clearly shown that the surface modification incurs higher specific surface area and smaller grain sizes of the CH without destruction of their integrity. Moreover, the introduced surface NaOH can trigger Cannizzaro disproportionation of surface-absorbed formaldehyde (HCHO) on Na-CH, resulting in catalytic transformation of HCHO into less-toxic formate and methoxy salts. The NaOH concentration during impregnating treatment has a great influence on HCHO adsorption and removal efficiency, while the impregnation time and temperature have little influence on the efficiency. When the CH was impregnated in 1 M NaOH aqueous solution for 0.5 h at room temperature, the HCHO removal efficiency at ambient temperature can reach about 80% with an initial HCHO concentration of 250 ppm. Moreover, the used Na-CH can be facilely regenerated via 1 min blow using a common electric hair dryer, with the generation of less toxic HCOOH and CH3OH and recovery of NaOH. Using such a mild, fast, and practical regeneration method, the regenerated Na-CH showed slight degradation in adsorption and removal capability toward HCHO. The enhanced performance of Na-CH obtained was attributed to the presence of NaOH and increase of specific surface area and surface hydroxyl groups. Considering no demand of noble metal for HCHO removal at ambient temperature and practical reusable capability of Na-CH under mild conditions, this work may provide some new insights into the design and fabrication of advanced catalysts for indoor air purification. PMID:23895134

Yu, Jiaguo; Li, Xinyang; Xu, Zhihua; Xiao, Wei

2013-09-01

354

Hormonal regulation of Na(+)-Ca2+ exchange in osteoblast-like cells.  

PubMed

We proposed a role for Na-Ca exchange in hormonally mediated bone resorption and recently characterized Na-dependent Ca transport in an osteoblast-like rat osteosarcoma cell line (UMR-106). To test whether calcemic agents alter Na(+)-Ca2+ exchange in osteoblasts, UMR cells were treated acutely or cultured in the absence or presence of calcemic agent for 24 h. Cells were then loaded with the Ca-sensitive dye fura-2 in the presence of 140 mM NaCl, no Ca, and the absence or presence of 0.3 mM ouabain. Cells were resuspended at 22 degrees C, and the fluorescence ratio at excitation wavelength of 340 and 380 nm was measured. An outward Na gradient was generated by removing extracellular Na and maintaining isotonicity with choline chloride. Na(+)-Ca2+ exchange was demonstrated by enhanced Ca uptake in ouabain-treated (Na-loaded) cells after the addition of 1.5 mM Ca. Acute addition of 10(-7) M PTH or 10(-6) M PGE2 had no effect on Na-dependent Ca uptake. However, 24 h treatment of cells with PTH, PGE2, or 1,25(OH)2D3 caused a dose-dependent inhibition of Na(+)-Ca2+ exchange. Using the Na-sensitive dye, SBFI, we also demonstrated that the effect was bidirectional; PTH inhibited Ca-dependent Na uptake comparably to its inhibition of Na-dependent Ca uptake. The effects of the calcemic agents were mimicked by 24 h treatment of the cells with 1 microM forskolin or 2 microM PMA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7976498

Short, C L; Monk, R D; Bushinsky, D A; Krieger, N S

1994-08-01

355

Energetics of Na+-dependent amino acid co-transport in Ehrlich ascites tumor cells.  

PubMed

The energy available from the Na+ electrochemical potential gradient (delta mu Na) has been evaluated in Ehrlich ascites tumor cells during accumulation of 2-aminoisobutyric acid. Cells were incubated in media of varying [Na+] (25-154 mM) in the presence of 0.25 mM 2-aminoisobutyric acid to establish maximum steady-state accumulation of the amino acid. Membrane potential (Vm) and intracellular Na+ activity (aNa) were estimated using standard electrophysiological techniques. In physiological saline ([Na+] = 154 mM) aNa is 4.4 +/- 0.6 mM, giving an apparent Na+ activity coefficient (gamma app) in the cytoplasm of 0.17 +/- 0.02. Vm under these conditions is -20.8 +/- 2.1 mV. From these values, delta mu Na = 9.9 +/- 0.8 kJ/mol. Concomitant determinations of 2-aminoisobutyric acid (AIB) accumulation show an energy requirement (delta mu AIB) of 8.5 +/- 0.5 kJ/mol. Stepwise reductions in extracellular [Na+] give parallel reductions in aNa, Vm and 2-aminoisobutyric acid accumulation. However, under all conditions tested the energy available from the Na+ electrochemical potential gradient exceeds that needed to drive 2-aminoisobutyric acid uptake. The effects of 2-aminoisobutyric acid on Vm have also been determined. Addition of AIB (10 mM) to steady-state cells leads to membrane depolarization (resting Vm = -22.1 +/- 1.3 mV; plus AIB Vm = -16.2 +/- 1.2 mV) within 1 min. Subsequent repolarization of the membrane to resting levels occurs within 10 min. The repolarization phase is blocked in the presence of ouabain (2 mM). The results establish that the energy available from the Na+ gradient is sufficient to serve as a source for 2-aminoisobutyric acid accumulation. PMID:3801480

Dawson, W D; Smith, T C

1987-02-12

356

Differential regulation of the renal sodium-phosphate cotransporters NaPi-IIa, NaPi-IIc, and PiT-2 in dietary potassium deficiency.  

PubMed

Dietary potassium (K) deficiency is accompanied by phosphaturia and decreased renal brush border membrane (BBM) vesicle sodium (Na)-dependent phosphate (P(i)) transport activity. Our laboratory previously showed that K deficiency in rats leads to increased abundance in the proximal tubule BBM of the apical Na-P(i) cotransporter NaPi-IIa, but that the activity, diffusion, and clustering of NaPi-IIa could be modulated by the altered lipid composition of the K-deficient BBM (Zajicek HK, Wang H, Puttaparthi K, Halaihel N, Markovich D, Shayman J, Beliveau R, Wilson P, Rogers T, Levi M. Kidney Int 60: 694-704, 2001; Inoue M, Digman MA, Cheng M, Breusegem SY, Halaihel N, Sorribas V, Mantulin WW, Gratton E, Barry NP, Levi M. J Biol Chem 279: 49160-49171, 2004). Here we investigated the role of the renal Na-P(i) cotransporters NaPi-IIc and PiT-2 in K deficiency. Using Western blotting, immunofluorescence, and quantitative real-time PCR, we found that, in rats and in mice, K deficiency is associated with a dramatic decrease in the NaPi-IIc protein abundance in proximal tubular BBM and in NaPi-IIc mRNA. In addition, we documented the presence of a third Na-coupled P(i) transporter in the renal BBM, PiT-2, whose abundance is also decreased by dietary K deficiency in rats and in mice. Finally, electron microscopy showed subcellular redistribution of NaPi-IIc in K deficiency: in control rats, NaPi-IIc immunolabel was primarily in BBM microvilli, whereas, in K-deficient rats, NaPi-IIc BBM label was reduced, and immunolabel was prevalent in cytoplasmic vesicles. In summary, our results demonstrate that decreases in BBM abundance of the phosphate transporter NaPi-IIc and also PiT-2 might contribute to the phosphaturia of dietary K deficiency, and that the three renal BBM phosphate transporters characterized so far can be differentially regulated by dietary perturbations. PMID:19493963

Breusegem, Sophia Y; Takahashi, Hideaki; Giral-Arnal, Hector; Wang, Xiaoxin; Jiang, Tao; Verlander, Jill W; Wilson, Paul; Miyazaki-Anzai, Shinobu; Sutherland, Eileen; Caldas, Yupanqui; Blaine, Judith T; Segawa, Hiroko; Miyamoto, Ken-ichi; Barry, Nicholas P; Levi, Moshe

2009-08-01

357

Beta-decay asymmetry and nuclear magnetic moment of 24Na m(T {1}/{2} = 20 ms)  

NASA Astrophysics Data System (ADS)

Polarized isomeric 24Na m(T {1}/{2} = 20 ms, I ? = 1 +) nuclei were produced by capture of polarized thermal neutrons in a NaF single crystal at room temperature. The asymmetric ?-decay radition of 24Na m was used to detect nuclear magnetic resonance signals yielding the magnetic moment |?( 24Na m)| = 1.930 (3) n.m. (uncorrected).

Heitjans, P.; Grupp, H.; Buttler, W.; Fujara, F.; Ackermann, H.; Drr, K.; Kiese, G.; Krblein, A.; Stckmann, H.-J.

1980-07-01

358

Involvement of Na+ in Active Uptake of Pyruvate in Mesophyll Chloroplasts of Some C4 Plants 1  

PubMed Central

An artificial Na+ gradient across the envelope (Na+ jump) enhanced pyruvate uptake in the dark into mesophyll chloroplasts of a C4 plant, Panicum miliaceum (NAD-malic enzyme type) (J Ohnishi, R Kanai [1987] FEBS Lett 219:347). In the present study, 22Na+ and pyruvate uptake were examined in mesophyll chloroplasts of several species of C4 plants. Enhancement of pyruvate uptake by a Na+ jump in the dark was also seen in mesophyll chloroplasts of Urochloa panicoides and Panicum maximum (phosphoenolpyruvate carboxykinase types) but not in Zea mays or Sorghum bicolor (NADP-malic enzyme types). In mesophyll chloroplasts of P. miliaceum and P. maximum, pyruvate in turn enhanced Na+ uptake in the dark when added together with Na+. When flux of endogenous Na+ was measured in these mesophyll chloroplasts preincubated with 22Na+, pyruvate addition induced Na+ influx, and the extent of the pyruvate-induced Na+ influx positively correlated with that of pyruvate uptake. A Na+/H+ exchange ionophore, monensin, nullified all the above mutual effects of Na+ and pyruvate in mesophyll chloroplasts of P. miliaceum, while it accelerated Na+ uptake and increased equilibrium level of chloroplast 22Na+. Measurements of initial uptake rates of pyruvate and Na+ gave a stoichiometry close to 1:1. These results point to Na+/pyruvate cotransport into mesophyll chloroplasts of some C4 plants. PMID:16667876

Ohnishi, Jun-ichi; Flugge, Ulf-Ingo; Heldt, Hans W.; Kanai, Ryuzi

1990-01-01

359

LABORATORY DETECTION AND SUBMILLIMETER SPECTRUM OF NaCCH (X~ 1 B. Z. LI AND L. M. ZIURYS1  

E-print Network

, Fujitaki, & Hirota 1989), NaH (Sastry, Herbst, & DeLucia 1981), and NaOH (e.g., Pearson & Trueblood 1973 Department of Chemistry, Arizona State University, Tempe, AZ 85287-1604 Received 1997 February 10; accepted these data, highly accurate rotational constants were determined. The detection of NaCN and Na

Ziurys, Lucy M.

360

SLC4A11 is an EIPA-sensitive Na+ permeable pHi regulator  

PubMed Central

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

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

2013-01-01

361

Actinic EUV mask inspection beyond 0.25 NA  

SciTech Connect

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

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

2008-08-06

362

Monensin Inhibition of Na+-Dependent HCO3- Transport Distinguishes It from Na+-Independent HCO3- Transport and Provides Evidence for Na+/HCO3- Symport in the Cyanobacterium Synechococcus UTEX 625.  

PubMed Central

The effect of monensin, an ionophore that mediates Na+/H+ exchange, on the activity of the inorganic carbon transport systems of the cyanobacterium Synechococcus UTEX 625 was investigated using transport assays based on the measurement of chlorophyll a fluorescence emission or 14C uptake. In Synechococcus cells grown in standing culture at about 20 [mu]M CO2 + HCO3-, 50 [mu]M monensin transiently inhibited active CO2 and Na+-independent HCO3- transport, intracellular CO2 and HCO3- accumulation, and photosynthesis in the presence but not in the absence of 25 mM Na+. These activities returned to near-normal levels within 15 min. Transient inhibition was attributed to monensin-mediated intracellular alkalinization, whereas recovery may have been facilitated by cellular mechanisms involved in pH homeostasis or by monensin-mediated H+ uptake with concomitant K+ efflux. In air-grown cells grown at 200 [mu]M CO2 + HCO3- and standing culture cells, Na+-dependent HCO3- transport, intracellular HCO3- accumulation, and photosynthesis were also inhibited by monensin, but there was little recovery in activity over time. However, normal photosynthetic activity could be restored to air-grown cells by the addition of carbonic anhydrase, which increased the rate of CO2 supply to the cells. This observation indicated that of all the processes required to support photosynthesis only Na+-dependent HCO3- transport was significantly inhibited by monensin. Monensin-mediated dissipation of the Na+ chemical gradient between the medium and the cells largely accounted for the decline in the HCO3- accumulation ratio from 751 to 55. The two HCO3- transport systems were further distinguished in that Na+-dependent HCO3- transport was inhibited by Li+, whereas Na+-independent HCO3- transport was not. It is suggested that Na+-dependent HCO3- transport involves an Na+/HCO3- symport mechanism that is energized by the Na+ electrochemical potential. PMID:12232177

Espie, G. S.; Kandasamy, R. A.

1994-01-01

363

Monensin Inhibition of Na+-Dependent HCO3- Transport Distinguishes It from Na+-Independent HCO3- Transport and Provides Evidence for Na+/HCO3- Symport in the Cyanobacterium Synechococcus UTEX 625.  

PubMed

The effect of monensin, an ionophore that mediates Na+/H+ exchange, on the activity of the inorganic carbon transport systems of the cyanobacterium Synechococcus UTEX 625 was investigated using transport assays based on the measurement of chlorophyll a fluorescence emission or 14C uptake. In Synechococcus cells grown in standing culture at about 20 [mu]M CO2 + HCO3-, 50 [mu]M monensin transiently inhibited active CO2 and Na+-independent HCO3- transport, intracellular CO2 and HCO3- accumulation, and photosynthesis in the presence but not in the absence of 25 mM Na+. These activities returned to near-normal levels within 15 min. Transient inhibition was attributed to monensin-mediated intracellular alkalinization, whereas recovery may have been facilitated by cellular mechanisms involved in pH homeostasis or by monensin-mediated H+ uptake with concomitant K+ efflux. In air-grown cells grown at 200 [mu]M CO2 + HCO3- and standing culture cells, Na+-dependent HCO3- transport, intracellular HCO3- accumulation, and photosynthesis were also inhibited by monensin, but there was little recovery in activity over time. However, normal photosynthetic activity could be restored to air-grown cells by the addition of carbonic anhydrase, which increased the rate of CO2 supply to the cells. This observation indicated that of all the processes required to support photosynthesis only Na+-dependent HCO3- transport was significantly inhibited by monensin. Monensin-mediated dissipation of the Na+ chemical gradient between the medium and the cells largely accounted for the decline in the HCO3- accumulation ratio from 751 to 55. The two HCO3- transport systems were further distinguished in that Na+-dependent HCO3- transport was inhibited by Li+, whereas Na+-independent HCO3- transport was not. It is suggested that Na+-dependent HCO3- transport involves an Na+/HCO3- symport mechanism that is energized by the Na+ electrochemical potential. PMID:12232177

Espie, G. S.; Kandasamy, R. A.

1994-04-01

364

Na8Au9.8(4)Ga7.2 and Na17Au15.87(2)Ga46.63: The diversity of pseudo 5-fold 0 Cross Mark symmetries in the Na-Au-Ga system  

SciTech Connect

The Na-rich part (similar to 30% Na) of the Na-Au-Ga system between NaAu2, NaGa4, and Na(22)Ga39 has been found to contain the ternary phases NasAug(8)(4)Ga-7.2 (I) and NavAu(5.87(2))Ga46.63 (II), according to the results of single crystal X-ray diffraction measurements. I is orthorhombic, Cmcm, a= 5.3040(1), b=24.519(5), c=14.573(3) A, and contains a network of clusters with local 5-fold symmetry along the a-axis. Such clusters are frequent building units in decagonal quasicrystals and their approximants. II is rhombohedral, a =16.325(2), c=35.242(7) A, and contains building blocks that are structurally. identical to the Bergman-type clusters as well as fused icosahedral units known with active metals, triels and late transition elements. II also contains a polycationic network with elements of the clathrate V type structure. Tight-binding electronic structure calculations using linear muffin-tin-orbital (LMTO) methods on idealized models of I and II indicate that both compounds are metallic with evident pseudogaps at the corresponding Fermi levels. The overall Hamilton bond populations are generally dominated by Au-Ga and Au-Au bonds in I and by Ga-Ga bonds in II; moreover, the Na-Au and Na-Ga contributions in I are unexpectedly large, 20% of the total. A similar involvement of sodium in covalent bonding has also been found in the electron-richer i-Nai(3)Aui(2)Gai(5) quasicrystal approximant. (C) 2013 Elsevier Inc. All rights reserved.

Smetana, Volodymyr [Ames Laboratory; Corbett, John D.; Miller, Gordon J. [Ames Laboratory

2013-08-29

365

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

SciTech Connect

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

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

2010-03-15

366

Mechanism of proximal NaCl reabsorption in the proximal tubule of the mammalian kidney.  

PubMed

In the mammalian proximal tubule NaCl reabsorption occurs by both passive and active transport processes. Passive NaCl reabsorption occurs in the presence of a high luminal chloride and a low luminal bicarbonate concentration. These anion gradients provide the driving forces for diffusive Na and Cl movement. Na is driven by the lumen positive PD effected by the greater permeability of the tubular wall to Cl than to HCO3. Cl is driven by its high tubular concentration. Passive NaCl reabsorption accounts for only about 10% to 15% of total proximal NaCl transport. The remaining proximal NaCl is reabsorbed by active transport processes and occurs both in the presence or absence of anion gradients reabsorption. Two mechanisms of active NaCl reabsorption participate in active NaCl reabsorption along the proximal tubule. Firstly, active NaCl reabsorption is electrogenic. In the early proximal tubule Na enters to cell coupled to organic solute transport. This Na reabsorption generates a lumen negative PD and effects "coupled" electrogenic NaCl reabsorption. This mechanism is limited by the supply of organic solutes and is blunted by the greater Na than Cl permeability in the proximal tubule; it probably can account for no more than 10% of proximal NaCl reabsorption. In the terminal proximal tubule, the proximal straight tubule, the apical membrane appears to possess a channel for Na entry. This Na reabsorption also generates a lumen negative PD and effects "simple" electrogenic NaCl reabsorption. This mechanism is limited by the low transport capacity of this segment and probably accounts for no more than 5% to 10% of total proximal NaCl reabsorption. The great bulk of proximal NaCl reabsorption occurs along the entire proximal tubule by active, transcellular electroneutral NaCl reabsorption. The precise cellular transport mechanisms responsible for this process are only recently being defined. At the apical membrane parallel ion exchangers are responsible for NaCl entry into the cell. Na enters via the apical membrane Na-H antiporter. Cl most likely crosses the apical membrane by some combination of Cl-OH and Cl-HCO2 exchangers but not via a Cl-HCO3 exchanger. The relative contributions of Cl-OH and Cl-HCO2 exchange have not been defined. There are two important considerations in this question. First is the availbility of OH versus HCO2. Although there is an infinite supply of OH and a small equilibrium supply of HCO2, it is possible that the luminal concentration of HCO2 could be increased by an USL that raises the concentration of HCO2 to a degree sufficient to supply H2CO2 recycling for physiological transcellular Cl transport rates.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2034928

Berry, C A; Rector, F C

1991-03-01

367

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

368

Elastic softening of alloy negative electrodes for Na-ion batteries  

NASA Astrophysics Data System (ADS)

Accurate description of the mechanical behavior of crystalline Na alloys is essential in establishing their electrochemical performance as well as their viability as anodes in Na-ion batteries. Using first principles simulations, we have investigated the intrinsic elastic properties of crystalline Na-M (M = Sn, Pb, Si and Ge) phases observed during Na intercalation. We have obtained the complete set of concentration-dependent anisotropic elastic constants as well as the average macroscopic elastic moduli of polycrystalline structures. We find that sodiation of pure M phases leads to a remarkable elastic softening that results in up to 75% deterioration of the elastic moduli. Our analysis of the electronic charge distribution demonstrates that the elastic softening during sodiation originates from a transition to weaker ionic interatomic bonding. Our results highlight the significance of the concentration dependence of the elastic moduli for the analysis of deformation behavior of Na alloy anodes of Na-ion batteries during sodiation and desodiation.

Mortazavi, Majid; Deng, Junkai; Shenoy, Vivek B.; Medhekar, Nikhil V.

2013-03-01

369

Crystal structure of alluaudite-type Na4Co(MoO4)3  

PubMed Central

The title compound, tetrasodium cobalt(II) tris[molybdate(IV)], was prepared by solid-state reactions. The structure is isotypic with Na3In2(AsO4)3 and Na3In2(PO4)3. The main structural feature is the presence of infinite chains of edge-sharing X 2O10 (X = Co/Na) dimers, which are linked by MoO4 tetrahedra, forming a three-dimensional framework enclosing two types of hexagonal tunnels in which Na+ cations reside. In this alluaudite structure, Co and Na atoms are located at the same general site with occupancies of 0.503?(5) and 0.497?(6), respectively. The other three Na and one of the two Mo atoms lie on special positions (site symmetries 2, -1, 2 and 2, respectively). The structure is compared with similar structures and other members of alluaudite family.

Nasri, Rawia; Fakhar Bourguiba, Noura; Zid, Mohamed Faouzi; Driss, Ahmed

2014-01-01

370

Structural Response of P2-Type NaxMnO2 against Na+ Intercalation  

NASA Astrophysics Data System (ADS)

P2-type NaxMnO2 (P63/mmc, Z = 2) with a layered rock-salt structure is a promising cathode material for low-cost sodium ion secondary batteries (SIBs). Here, we performed an ex situ synchrotron radiation x-ray structural analysis of NaxMnO2 (0.43 ? x ? 0.71) against Na+ concentration (x). We found that the thicknesses (dNaO\\scale70%2) of the NaO2 layer is nearly independent of x, in a sharp contrast to the rapid decrease observed in isostructural NaxCoO2. In addition, the site energy differences [?? = ?1 - ?2; ?1 (?2) is the site energy at Na1 (Na2)] in NaxMnO2 are much smaller than those in NaxCoO2. These observations are interpreted in terms of the screening effect of the Na+ charge in NaxMnO2.

Shimono, Takahiro; Tanabe, Daiki; Kobayashi, Wataru; Moritomo, Yutaka

2013-08-01

371

Cu2Sb thin films as anode for Na-ion batteries  

SciTech Connect

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

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

2013-01-01

372

Enhancement of enzymatic digestibility of Eucalyptus grandis pretreated by NaOH catalyzed steam explosion.  

PubMed

NaOH catalyzed steam explosion was applied to improve the enzymatic digestibility of Eucalyptus grandis. The impregnation of wood chip with NaOH solutions before steam explosion was carried out to investigate the effects of alkaline catalysis on solid recovery, enzymatic digestibility, and glucose recovery. The lignin removal was significantly affected by NaOH as a catalyst and the glucose recovery increased with increased severity index. The use of NaOH showed higher enzymatic digestibility than the use of water at most severity indexes due to the delignification of biomass and the increase of accessibility to cellulose of enzyme. The maximum glucose recovery was 65.55% having 4.4361 of severity index with 7wt.% of NaOH catalyzed steam explosion at 210C during 9min. NaOH catalyzed steam explosion was effective to enhance the enzymatic digestibility due to the removal of lignin. PMID:22939603

Park, Ji-Yeon; Kang, Minsu; Kim, Jun Seok; Lee, Joon-Pyo; Choi, Won-Il; Lee, Jin-Suk

2012-11-01

373

Inhibition of voltage-gated Na+ current by nanosecond pulsed electric field (nsPEF) is not mediated by Na+ influx or Ca2+ signaling  

PubMed Central

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 (INa) 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 Ca2+-dependent mechanism. We found that a single 300 ns electric pulse at 1.65.3 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 increase was efficiently buffered by the pipette solution so that the increase in the intracellular concentration of Na+ ([Na]i) did not exceed 23 mM. [Na]i increased uniformly over the cell volume and showed no additional peaks immediately below the plasma membrane. Concurrently, nsPEF reduced VG INa by 3060% (at 4 and 5.3 kV/cm). In control experiments, an even greater increase of Na+ in the pipette (by 5 mM) did not attenuate VG INa, thereby indicating that the nsPEF-induced Na+ influx was not the cause of VG INa inhibition. Similarly, adding 20 mM of a fast Ca2+ 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 INa by nsPEF. These findings point to possible Ca2+-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.

2012-01-01

374

Ethoxyzolamide Differentially Inhibits CO2 Uptake and Na+-Independent and Na+-Dependent HCO3- Uptake in the Cyanobacterium Synechococcus sp. UTEX 625.  

PubMed Central

The effects of ethoxyzolamide (EZ), a carbonic anhydrase inhibitor, on the active CO2 and Na+-independent and Na+-dependent HCO3- transport systems of the unicellular cyanobacterium Synechococcus sp. UTEX 625 were examined. Measurements of transport and accumulation using radiochemical, fluorometric, and mass spectrometric assays indicated that active CO2 transport and active Na+-independent HCO3- transport were inhibited by EZ. However, Na+-independent HCO3- transport was about 1 order of magnitude more sensitive to EZ inhibition than was CO2 transport (50% inhibition = 12 [mu]M versus 80 [mu]M). The data suggest that both the active CO2 (G.D. Price, M.R. Badger [1989] Plant Physiol 89: 37-43) and the Na+ -independent HCO3 - transport systems possessed carbonic anhydrase-like activity as part of their mechanism of action. In contrast, Na+-dependent HCO3- transport was only partially (50% inhibition = 230 [mu]M) and noncompetitively inhibited by EZ. The collective evidence suggested that EZ inhibition of Na+ -dependent HCO3- transport was an indirect consequence of the action of EZ on the CO2 transport system, rather than a direct effect on HCO3- transport. A model is presented in which the core of the inorganic carbon translocating system is formed by Na+-dependent HCO3- transport and the CO2 transport system. It is argued that the Na+-independent HCO3 - utilizing system was not directly involved in translocation, but converted HCO3- to CO2 for use in CO2 transport. PMID:12226376

Tyrrell, P. N.; Kandasamy, R. A.; Crotty, C. M.; Espie, G. S.

1996-01-01

375

Ethoxyzolamide Differentially Inhibits CO2 Uptake and Na+-Independent and Na+-Dependent HCO3- Uptake in the Cyanobacterium Synechococcus sp. UTEX 625.  

PubMed

The effects of ethoxyzolamide (EZ), a carbonic anhydrase inhibitor, on the active CO2 and Na+-independent and Na+-dependent HCO3- transport systems of the unicellular cyanobacterium Synechococcus sp. UTEX 625 were examined. Measurements of transport and accumulation using radiochemical, fluorometric, and mass spectrometric assays indicated that active CO2 transport and active Na+-independent HCO3- transport were inhibited by EZ. However, Na+-independent HCO3- transport was about 1 order of magnitude more sensitive to EZ inhibition than was CO2 transport (50% inhibition = 12 [mu]M versus 80 [mu]M). The data suggest that both the active CO2 (G.D. Price, M.R. Badger [1989] Plant Physiol 89: 37-43) and the Na+ -independent HCO3 - transport systems possessed carbonic anhydrase-like activity as part of their mechanism of action. In contrast, Na+-dependent HCO3- transport was only partially (50% inhibition = 230 [mu]M) and noncompetitively inhibited by EZ. The collective evidence suggested that EZ inhibition of Na+ -dependent HCO3- transport was an indirect consequence of the action of EZ on the CO2 transport system, rather than a direct effect on HCO3- transport. A model is presented in which the core of the inorganic carbon translocating system is formed by Na+-dependent HCO3- transport and the CO2 transport system. It is argued that the Na+-independent HCO3 - utilizing system was not directly involved in translocation, but converted HCO3- to CO2 for use in CO2 transport. PMID:12226376

Tyrrell, P. N.; Kandasamy, R. A.; Crotty, C. M.; Espie, G. S.

1996-09-01

376

NaV1.5 Na? channels allosterically regulate the NHE-1 exchanger and promote the activity of breast cancer cell invadopodia.  

PubMed

The degradation of the extracellular matrix by cancer cells represents an essential step in metastatic progression and this is performed by cancer cell structures called invadopodia. NaV1.5 (also known as SCN5A) Na(+) channels are overexpressed in breast cancer tumours and are associated with metastatic occurrence. It has been previously shown that NaV1.5 activity enhances breast cancer cell invasiveness through perimembrane acidification and subsequent degradation of the extracellular matrix by cysteine cathepsins. Here, we show that NaV1.5 colocalises with Na(+)/H(+) exchanger type 1 (NHE-1) and caveolin-1 at the sites of matrix remodelling in invadopodia of MDA-MB-231 breast cancer cells. NHE-1, NaV1.5 and caveolin-1 co-immunoprecipitated, which indicates a close association between these proteins. We found that the expression of NaV1.5 was responsible for the allosteric modulation of NHE-1, rendering it more active at the intracellular pH range of 6.4-7; thus, it potentially extrudes more protons into the extracellular space. Furthermore, NaV1.5 expression increased Src kinase activity and the phosphorylation (Y421) of the actin-nucleation-promoting factor cortactin, modified F-actin polymerisation and promoted the acquisition of an invasive morphology in these cells. Taken together, our study suggests that NaV1.5 is a central regulator of invadopodia formation and activity in breast cancer cells. PMID:23902689

Brisson, Lucie; Driffort, Virginie; Benoist, Lauriane; Poet, Mallorie; Counillon, Laurent; Antelmi, Ester; Rubino, Rosa; Besson, Pierre; Labbal, Fabien; Chevalier, Stphan; Reshkin, Stephan J; Gore, Jacques; Roger, Sbastien

2013-11-01

377

Regulation of Na+,K(+)-ATPase and the Na+/K+/Cl- co-transporter in the renal epithelial cell line NBL-1 under osmotic stress.  

PubMed

The long-term adaptation of the Na+,K(+)-ATPase to hypertonicity was studied using the bovine renal epithelial cell line NBL-1. Na+,K(+)-ATPase activity measured in intact cells as the ouabain-sensitive fraction of Rb+ uptake was stimulated (40% above controls) after incubating the cells in hypertonic medium. This stimulation was not correlated with significant changes in the amount of Na+,K(+)-ATPase alpha 1 subunit protein. Nevertheless, the amount of alpha 1 but not beta 1 subunit mRNA progressively increased after hypertonic shock (3-4-fold above basal values). These results suggest that the alpha 1 subunit gene is modulated by medium osmolarity, although this does not necessarily involve enhanced translation of the mRNA into active alpha 1 protein. Indeed, the increase in the biological activity of the Na+,K(+)-ATPase is abolished when the electrochemical Na+ transmembrane gradient is depleted by monensin, which is consistent with a post-translational effect on the activity of the sodium pump. A furosemide-sensitive component of Rb+ uptake, attributable to Na+/K+/Cl- co-transporter activity, was very low when cells were cultured in a regular medium, but was greatly induced after hypertonic shock. This induction could not be blocked by cycloheximide. Colcemide addition slightly reduced the absolute increase in Na+/K+/Cl- co-transporter activity, while cytochalasin B significantly potentiated the effect triggered by hypertonic shock. It is concluded: (i) that in NBL-1 cells the alpha 1 but not the beta 1 subunit of the Na+,K(+)-ATPase is encoded by an osmotically sensitive gene, and (ii) that the Na+/K+/Cl- co-transporter, although an osmotically sensitive carrier, is induced by a mechanism that is independent of protein synthesis but may rely, in an undetermined manner, on the structure of the cytoskeletal network. PMID:8912665

Ferrer-Martinez, A; Casado, F J; Felipe, A; Pastor-Anglada, M

1996-10-15

378

Resonance production at SPS energies: CERES and NA49  

NASA Astrophysics Data System (ADS)

We present results on resonance production by the NA49 and CERES collaborations. The measurement of the differential yields and spectral distributions of the K*(892), ?(1232), ?, ? and ?(1520) resonances from their leptonic and hadronic decay channels at different C.M.S. energies and for various colliding systems allows us to study in-medium modifications of the resonance mass, width and yield and constrains the properties of the hadronic phase. For K*(892)0, a strong system size dependence of the yield relative to kaon production is found. The production of the ?(1232) resonance is consistent with thermal model expectations. ? meson spectra and yields reconstructed in the leptonic and hadronic decay channels are in agreement. Low-mass dilepton spectra indicate significant regeneration of the ? meson and a strong modification of the ? spectral function.

Busch, O.

2012-11-01

379

Na/Ca exchange and contraction of the heart  

PubMed Central

Sodium-calcium exchange (NCX) is the major calcium (Ca) efflux mechanism of ventricular cardiomyocytes. Consequently the exchanger plays a critical role in the regulation of cellular Ca content and hence contractility. Reductions in Ca efflux by the exchanger, such as those produced by elevated intracellular sodium (Na) in response to cardiac glycosides, raise sarcoplasmic reticulum (SR) Ca stores. The result is an increased Ca transient and cardiac contractility. Enhanced Ca efflux activity by the exchanger, for example during heart failure, may reduce diadic cleft Ca and excitation-contraction (EC) coupling gain. This aggravates the impaired contractility associated with SR Ca ATPase dysfunction and reduced SR Ca load in failing heart muscle. Recent data from our laboratories indicate that NCX can also impact the efficiency of EC coupling and contractility independent of SR Ca load through diadic cleft priming with Ca during the upstroke of the action potential. PMID:23770352

Ottolia, Michela; Torres, Natalia; Bridge, John H. B.; Philipson, Kenneth D.; Goldhaber, Joshua I.

2013-01-01

380

Physical Manipulation of the Na/K Pump  

NASA Astrophysics Data System (ADS)

It has been demonstrated that a well-designed oscillating electric field can synchronize and modulate the functions of the Na+/K+ ATPase pump, a ubiquitous active transporter in the cell membrane. Current work aims to improve this technique in order to synchronize the individual steps in the pumping cycle, allowing all of the individual pumps to run simultaneously. Using frog skeletal muscle fibers and the double Vaseline-gap voltage clamp technique, we are working to design wave pulses, which will isolate the voltage dependent steps of the active ion transport. This will improve the signal-to-noise ratio and provide insight into the protein conformation changes that occur during active transport.

Eve, David; Mathis, Clausell; Chen, Wei

2012-02-01

381

Two-Photon Cooperative Absorption in Colliding Cold Na Atoms  

NASA Astrophysics Data System (ADS)

Two-photon cooperative absorption is common in solid-state physics. In a sample of trapped cold atoms, this effect may open up new possibilities for the study of nonlinear effects. The experiment described herein starts with two colliding Na atoms in the S hyperfine ground state. The pair absorb two photons, resulting in both a P1/2 and a P3/2 atom. This excitation is observed by ionization using an external light source. A simple model that considers only dipole-dipole interactions between the atoms allows us to understand the basic features observed in the experimental results. Both the pair of generated atoms and the photons originating from their decay are correlated and may have interesting applications that remain to be explored.

Pedrozo-Peafiel, E.; Paiva, R. R.; Vivanco, F. J.; Bagnato, V. S.; Farias, K. M.

2012-06-01

382

Photoassociation of NaRb with an asymmetric laser pulse  

NASA Astrophysics Data System (ADS)

We investigate the photoassociation dynamics of cold NaRb molecule controlled by an asymmetric laser pulse called slowly-turned-on and rapidly-turned-off (STRT) laser pulse. This new shaped laser pulse has a remarkable merit, compared with the typical Gauss-type pulses, so that we can efficiently associate molecules with the state expected instead of going back to the continuum state. Using the three-state model, we solve the quantum mechanical equation with the "split operator-Fourier transform" method under the rotating-wave approximation (RWA) in propagation of the wave packet. By the projection of the obtained wave function onto each vibrational state, we can get the vibrational population of the ground electronic state. The results reveal that, with the STRT laser pulse, an efficient photoassociation process can be achieved and the vibrational distribution in the ground state can be controlled by the laser parameters.

Zhang, ChangZhe; Zheng, Bin; Niu, YuQuan; Wei, Wei; Meng, QingTian

2014-10-01

383

Nanoindentation Study of Na-Geopolymers Exposed to High Temperatures  

NASA Astrophysics Data System (ADS)

This paper reports the usefulness of nanoindentation as a characterization and monitoring tool for studying thermal behaviour of Geopolymer materials. The influence of the manufacturing process of Na-Geopolymers in their micro-mechanical properties and thermal behaviour has been studied. Two types of metakaolin-based geopolymer panels with almost identical composition were prepared by injection and pouring methods. Micro-mechanical properties of the two samples exposed to high temperatures up to 1000 C were studied by nanoindentation technique, supplemented by X-ray diffraction (XRD), Nuclear magnetic resonance (NMR), Thermogravimetric analysis (TGA) and Microscopy. Remarkable differences in micro-mechanical properties and thermal behaviour between the two samples were found. Statistical nanoindentation has been successfully used to provide information about the micro-mechanical properties of different phases in the material and their volume distributions.

Belea, I.; Zhu, W.

384

An Automated Relative Time Calibration for the MoNA  

NASA Astrophysics Data System (ADS)

The Modular Neutron Array (MoNA) is a highly efficient time-of-flight neutron detector consisting of 144 individual plastic scintillation bars. It is used in conjunction with a sweeper magnet and charged particle detectors at the National Superconducting Cyclotron Laboratory to reconstruct neutron separation energies of neutron unbound nuclei from the velocities of the ejected neutrons and residual fragments. The PMT signals from each bar in the array have slightly different transit times. An offset to calibrate the bars relative to each other must be calculated using cosmic ray muons. The current relative calibration employs a labor intensive and imprecise method. A more precise procedure for finding the weighted average of the time difference between any two bars and calculating the calibration values was developed and automated. Details of the procedure will be presented.

Albertson, Daniel

2006-10-01

385

Long Life Na/NiCl2 Cells  

NASA Technical Reports Server (NTRS)

The premature capacity failure of Na/NiCl2 secondary cells due to agglomeration of nickel particles on the surface of the NiCl2 cathode is prevented by addition of a minor amount such as 10 percent by weight of a transition metal such as Co, Fe or Mn to the cathode. The chlorides of the transition metals have lower potentials than nickel chloride and chlorinate during charge. A uniform dispersion of the transition metals in the cathodes prevents agglomeration of nickel, maintains morphology of the electrode, maintains the electrochemical area of the electrode and thus maintains capacity of the electrode. The additives do not effect sintering. The addition of sulfur to the liquid catholyte is expected to further reduce agglomeration of nickel in the cathode.

Bugga, Ratnakumar V. (Inventor); Surampudi, Subbarao (Inventor); Halpert, Gerald (Inventor)

1996-01-01

386

Investigations of Semileptonic Kaon Decays at the NA48 Experiment  

NASA Astrophysics Data System (ADS)

Semileptonic decays of charged and neutral kaons, KL --> ?+/-e-/+?e (Ke30), KL --> ?+/-?-/+?? (K?30) and K+/- --> ?0e+/-?e (Ke3+/-), were used to study the strangeness-changing weak interactions of hadrons. High statistics data samples of reconstructed events recorded by the NA48 experiment were analyzed to obtain the Dalitz plot densities. Investigations of all possible Lorentz-covariant couplings were performed and vector f+(q2), f0(q2), scalar fS and tensor fT contributions to the weak interaction were measured. Assuming only vector-axial couplings both the linear and quadratic terms of the momentum transferred expansion of the vector form factors were obtained. Alternatively, a fit to a pole form factor was performed.

Dyulendarova, Milena

2007-04-01

387

Structure and Function of Na+-Symporters with Inverted Repeats  

PubMed Central

Summary Symporters are membrane proteins that couple energy stored in electrochemical potential gradients to drive the cotransport of molecules and ions into cells. Traditionally, proteins are classified into gene families based on sequence homology and functional properties, e.g. the sodium glucose (SLC5 or Sodium Solute Symporter Family, SSS or SSF) and GABA (SLC6 or Neurotransmitter Sodium Symporter Family, NSS or SNF) symporter families [1-4]. Recently, it has been established that four Na+-symporter proteins with unrelated sequences have a common structural core containing an inverted repeat of 5 transmembrane (TM) helices [5-8]. Analysis of these four structures reveals that they reside in different conformations along the transport cycle providing atomic insight into the mechanism of sodium solute cotransport. PMID:19631523

Abramson, Jeff; Wright, Ernest M.

2009-01-01

388

A facile route for the preparation of morphology-controlled NaTaO 3 films  

Microsoft Academic Search

Ternary metal oxide films have being attracting increasing attention because of their special properties and potential applications in many important areas. In this paper, we report a facile hydrothermal route for the preparation of NaTaO3 thin films on tantalum foils with controlled morphology. In the NaOH solution, the morphology of crystals in the resultant NaTaO3 film changed from nanocubes to

Xingfu Zhou; Ying Chen; Hua Mei; Zhaolin Hu; Yiqun Fan

2008-01-01

389

Evidence for an amiloride sensitive Na + pathway in the amphibian diluting segment induced by K + adaptation  

Microsoft Academic Search

The effect of amiloride on cell membrane potentials and intracellular Na activity (Nai) was tested in early distal tubules of the isolated perfused kidney of control and of K-adapted (high-K diet)Amphiuma. Conventional and Na-sensitive liquid ion-exchanger microelectrodes were employed to measure the peritubular cell membrane potential (PDpt), the transepithelial potential difference (PDte) and the Na electrochemical gradient across the peritubular

Hans Oberleithner; Florian Lang; Wenhui Wang; Georg Messner; Peter Deetjen

1983-01-01

390

Na,K-ATPase Activity in Mouse Muscle is Regulated by AMPK and PGC1?  

Microsoft Academic Search

Na,K-ATPase activity, which is crucial for skeletal muscle function, undergoes acute and long-term regulation in response\\u000a to muscle activity. The aim of the present study was to test the hypothesis that AMP kinase (AMPK) and the transcriptional\\u000a coactivator PGC-1? are underlying factors in long-term regulation of Na,K-ATPase isoform (?,? and PLM) abundance and Na+ affinity. Repeated treatment of mice with

Maria S. Ingwersen; Michael Kristensen; Henriette Pilegaard; Jrgen F. P. Wojtaszewski; Erik A. Richter; Carsten Juel

2011-01-01

391

Ischemia-induced phosphorylation of phospholemman directly activates rat cardiac Na\\/K ATPase  

Microsoft Academic Search

Regulation of the Na\\/K ATPase by protein kinases is model-specific. We have observed a profound activation of the sarcolemmal Na\\/K ATPase during cardiac ischemia, which is masked by an inhibitor of the enzyme in the cytosol. The aim of these studies was to characterize the pathways involved in this activation in the Langendorff-perfused rat heart. Na\\/K ATPase activity was determined

William Fuller; Philip Eaton; James R. Bell; Michael J. Shattock

2004-01-01

392

Regulation of durum wheat Na + \\/H + exchanger TdSOS1 by phosphorylation  

Microsoft Academic Search

We have identified a plasma membrane Na+\\/H+ exchanger from durum wheat, designated TdSOS1. Heterologous expression of TdSOS1 in a yeast strain lacking endogenous Na+ efflux proteins showed complementation of the Na+- and Li+-sensitive phenotype by a mechanism involving cation efflux. Salt tolerance conferred by TdSOS1 was maximal when co-expressed\\u000a with the Arabidopsis protein kinase complex SOS2\\/SOS3. In vitro phosphorylation of

Kaouthar Feki; Francisco J. Quintero; Jose M. Pardo; Khaled Masmoudi

393

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

Microsoft Academic Search

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

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

1994-01-01

394

Contrasting role of Na + ions in modulating Cu +2 or Cd +2 induced hepatocyte toxicity  

Microsoft Academic Search

Previously we showed that hepatocyte lysis induced by Cu+2\\/Cd+2 could be partly attributed to membrane lipid peroxidation induced by Cu+2 or mitochondrial toxicity induced by Cd+2[5]. Changes in Na+ and Ca+2 homeostasis induced when Cu+2 was incubated with hepatocytes markedly differed from that induced by Cd+2. Na+ omission from the media or addition of the Na+\\/H+ exchange inhibitor 5-(N,N-dimethyl)-amiloride markedly

Jalal Pourahmad; Peter J. OBrien

2000-01-01

395

Developmental changes in ?-subunit composition of Na,K-ATPase in the Drosophila eye  

Microsoft Academic Search

The Drosophila genome contains at least three loci for the Na,K-ATPase ?-subunit; however, only the protein products of nrv1 and nrv2 have been characterized hitherto. Here, we provide evidence that nrv3 also encodes for a functional Na,K-ATPase ?-subunit, as its protein product co-precipitates with the Na,K-ATPase ?-subunit.\\u000a Nrv3 expression in adult flies is restricted to the nervous system in which

Otto Baumann; Paul M. Salvaterra; Kunio Takeyasu

2010-01-01

396

Thermal and carbothermic decomposition of Na 2 CO 3 and Li 2 CO 3  

Microsoft Academic Search

In order to elucidate the decomposition mechanism of Na2CO3 and Li2CO3 in mold-powder systems employed in the continuous casting of steel, decompositions of Na2CO3 and Li2CO3 were investigated using thermogravimetric (TG) and differential scanning calorimetric (DSC) methods at temperatures up to\\u000a 1200 C, under a flow of argon gas. For the case of pure Na2CO3, the thermal decomposition started from

Jong-Wan Kim; Hae-Geon Lee

2001-01-01

397

Physiological responses to NaCl stress in three wild species of potato in vitro  

Microsoft Academic Search

In this study, responses of wild species of potato to NaCl stress were investigated in vitro. In S. stoloniferum and S. bulbosum, length of the shoot, fresh and dry weight, photosynthetic pigments, K+ concentration, K+\\/Na+ ratio, ascorbate pool, anthocyanin, and phenolic and flavonoid compounds were decreased in response to salinity. In these\\u000a species, salinity increased the level of Na+, lipid

Fatemeh Daneshmand; Mohammad Javad Arvin; Khosrow Manouchehri Kalantari

2010-01-01

398

Further evidence for an inverse relationship between macula densa NaCl concentration and filtration rate  

Microsoft Academic Search

It has been concluded that tubulo-glomerular feedback mechanism is triggered by changes in NaCl concentration ([NaCl]) at the macula densa. This conclusion is based on the demonstration that changes in filtration rate produced during retrograde perfusion of the loop of Henle depend upon the perfusate [NaCl]. Experiments were performed to evaluate whether the effect on glomerular function of orthograde perfusion

Josephine Briggs; Gisela Schubert; Jtirgen Schnermann

1982-01-01

399

Structure, function and regulation of Na,K-ATPase in the kidney  

Microsoft Academic Search

All zones of mammalian kidney, except the papilla, are abundant sources of Na,K-ATPase. The inner stripe of the red outer medulla of rabbit or pig kidney served as the starting material for the first successful purification of the Na,K-pump or Na,K-ATPase [1]. In this tissue the basolateral cell membranes of the predominant structure, the medullary thick ascending limb of Henle

Peter L Jrgensen

1986-01-01

400

Trehalose-Producing Enzymes MTSase and MTHase in Anabaena 7120 Under NaCl Stress  

Microsoft Academic Search

Salt tolerance, a multigenic trait, necessitates knowledge about biosynthesis and function of candidate gene(s) at the cellular\\u000a level. Among the osmolytes, trehalose biosynthesis in cyanobacteria facing NaCl stress is little understood. Anabaena 7120 filaments exposed to 150mm NaCl fragmented and recovered on transfer to NaCl medium with the increased heterocysts frequency (7%) over the control\\u000a (4%). Cells failed to retain

Ravi K. Asthana; Subhasha Nigam; Archana Maurya; Arvind M. Kayastha; Sureshwar P. Singh

2008-01-01

401

Sex Differences in Electrophysiological and Behavioral Responses to NaCl Taste  

Microsoft Academic Search

We tested the hypothesis that sex differences in preference for NaCl are attributable to estrogen-mediated alterations in gustatory processing. Electrophysiological responses of the chorda tympani nerve to NaCl were blunted by estrogen treatment in ovariectomized female rats, suggesting that females are less sensitive to concentrated NaCl solutions during high estrogen conditions. In contrast, after a taste aversion was conditioned to

Kathleen S. Curtis; Robert J. Contreras

2006-01-01

402

Determination of the composition of H2 O-NaCl-CaCl2  

E-print Network

-Jones and Samson, 1990; Naden, 1996; Bakker, 2003; Chi and Ni, 2007). While each model appears to work well over) -25 -20 -15 -10 -5 0 20 25 30 35 This study Bakker (2003) Experimental Salinity Calculated Temperature NaClCaCl2 H2O E CaCl2·4H2O NaClCaCl2 H2O_NaCl_CaCl2 (Chi and Ni, 2007) + Aqso1e (Bakker, 2003) Calcic

Bodnar, Robert J.

403

Die wirkung steigender konzentrationen von natriumhydrogenkarbonat in wasserkulturen und die gegenwirkung des na-humats  

Microsoft Academic Search

\\u000a AbstraktDie Wirkung steigender Konzentrationen von NaHCO3 auf die Ausfllung des Eisens in einer Nhrlsung sowie die durch das Hydrogenkarbonat bedingte Hemmung des Wachstums der\\u000a Pflanzen (begleitet von Chlorose) und zugleich die Gegenwirkung des Na-Humats wurden erforscht. Unter der Einwirkung von NaHCO3 wurde eine Verminderung des Eisengehaltes und eine Erhhung des Verhltnisses P\\/Fe in den Sprossen festgestellt; in Anwesenheit\\u000a von Humat

Maria Badurowa; S. Gumi?ski; Anna Suder-Moraw

1967-01-01

404

Effect of diphenyl diselenide, diphenyl ditelluride and ebselen on cerebral Na +, K +ATPase activity in rats  

Microsoft Academic Search

In the present study, we investigated the in vitro effect of diphenyl ditelluride, diphenyl diselenide and ebselen on Na+, K+-ATPase activity of rat brain. The results demonstrated that all compounds significantly inhibited (in the ?M range) Na+, K+-ATPase activity. Diphenyl ditelluride, at low concentrations, provoked an increase in Na+, K+-ATPase activity. Dithiothreitol (DTT), at 3mM, protected the inhibition caused by

V. C. Borges; J. B. T. Rocha; C. W. Nogueira

2005-01-01

405

NaCl induced changes in ionically bound peroxidase activity in roots of rice seedlings  

Microsoft Academic Search

The changes in ionically bound peroxidase activity in roots of NaCl-stressed rice seedlings and their correlation with root\\u000a growth were investigated. Increasing concentrations of NaCl from 50 to 150 mM progressively decreases root growth. The reduction\\u000a of root growth by NaCl is closely correlated with the increase in ionically bound peroxidase activity. Since proline and ammonium\\u000a accumulations are associated with

Chuan Chi Lin; Ching Huei Kao

1999-01-01

406

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

Microsoft Academic Search

This work investigated whether the preference for NaCl solution is shifted to more palatable solutions in the adult male sodium-depleted rat (n=610 per group). Animals had daily access to three bottles, one containing water, another 1.8% NaCl (300 mM), and a third containing 0.9% NaCl (150 mM), Gatorade (orangeOG or grape flavoredGG), orange juice (sweetened or unsweetened, from concentrate), or

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

2002-01-01

407

NaF Activates MAPKs and Induces Apoptosis in Odontoblast-like Cells  

Microsoft Academic Search

The cytotoxic effects of fluoride on odontoblasts are not clear. In this study, we examined whether NaF induces apoptosis in MDPC-23 odontoblast-like cells and the involvement of mitogen-activated protein kinase (MAPK) signaling pathways in NaF-induced apoptosis. MDPC-23 cells incubated with 5 mM NaF for 24 hrs exhibited caspase-3 activation, cleavage of poly(ADP-ribose) polymerase, DNA fragmentation, and an increase in cytoplasmic

H. Karube; G. Nishitai; K. Inageda; H. Kurosu; M. Matsuoka

2009-01-01

408

Pulsed-laser mode competition with a Na-colored intracavity flame  

Microsoft Academic Search

A mode competition effect is observed with a Na-colored H2-O2-Ar flame located inside the cavity of a pulsed tunable dye laser tuned near one of the D-lines. When the Na-concentration is sufficiently high, laser action in the dominant mode is temporarily suppressed and develops in an adjacent mode. Meantime, the saturation of the Na-vapor progresses and, ultimately, laser action in

C. A. van Dijk; C. T. J. Alkemade; P. J. T. Zeegers

1978-01-01

409

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

PubMed Central

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

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

2013-01-01

410

The oxidation of MAR M247 superalloy with Na 2SO 4 coating  

Microsoft Academic Search

Tungsten-bearing and Al2O3-forming superalloy, MAR M247, with and without Na2SO4 coatings were oxidized in still air at 1000, 1100 and 1200K for 4120h to investigate the oxidation and hot corrosion behaviors. The results showed that the deposition of Na2SO4 accelerated the oxidation of alloy at all temperatures tested. The weight losses of specimens with and without Na2SO4 coating take place

Chaur-Jeng Wang; Jiann-Sheng Lin

2002-01-01

411

Structural and functional analysis of the Na+/H+ exchanger  

PubMed Central

The mammalian NHE (Na+/H+ exchanger) is a ubiquitously expressed integral membrane protein that regulates intracellular pH by removing a proton in exchange for an extracellular sodium ion. Of the nine known isoforms of the mammalian NHEs, the first isoform discovered (NHE1) is the most thoroughly characterized. NHE1 is involved in numerous physiological processes in mammals, including regulation of intracellular pH, cell-volume control, cytoskeletal organization, heart disease and cancer. NHE comprises two domains: an N-terminal membrane domain that functions to transport ions, and a C-terminal cytoplasmic regulatory domain that regulates the activity and mediates cytoskeletal interactions. Although the exact mechanism of transport by NHE1 remains elusive, recent studies have identified amino acid residues that are important for NHE function. In addition, progress has been made regarding the elucidation of the structure of NHEs. Specifically, the structure of a single TM (transmembrane) segment from NHE1 has been solved, and the high-resolution structure of the bacterial Na+/H+ antiporter NhaA has recently been elucidated. In this review we discuss what is known about both functional and structural aspects of NHE1. We relate the known structural data for NHE1 to the NhaA structure, where TM IV of NHE1 shows surprising structural similarity with TM IV of NhaA, despite little primary sequence similarity. Further experiments that will be required to fully understand the mechanism of transport and regulation of the NHE1 protein are discussed. PMID:17209804

Slepkov, Emily R.; Rainey, Jan K.; Sykes, Brian D.; Fliegel, Larry

2007-01-01

412

Mechanisms of renal NaCl retention in proteinuric disease.  

PubMed

In diseases with proteinuria, for example nephrotic syndrome and pre-eclampsia, there often are suppression of plasma renin-angiotensin-aldosterone system components, expansion of extracellular volume and avid renal sodium retention. Mechanisms of sodium retention in proteinuria are reviewed. In animal models of nephrotic syndrome, the amiloride-sensitive epithelial sodium channel ENaC is activated while more proximal renal Na(+) transporters are down-regulated. With suppressed plasma aldosterone concentration and little change in ENaC abundance in nephrotic syndrome, the alternative modality of proteolytic activation of ENaC has been explored. Proteolysis leads to putative release of an inhibitory peptide from the extracellular domain of the ? ENaC subunit. This leads to full activation of the channel. Plasminogen has been demonstrated in urine from patients with nephrotic syndrome and pre-eclampsia. Urine plasminogen correlates with urine albumin and is activated to plasmin within the urinary space by urokinase-type plasminogen activator. This agrees with aberrant filtration across an injured glomerular barrier independent of the primary disease. Pure plasmin and urine samples containing plasmin activate inward current in single murine collecting duct cells. In this study, it is shown that human lymphocytes may be used to uncover the effect of urine plasmin on amiloride- and aprotinin-sensitive inward currents. Data from hypertensive rat models show that protease inhibitors may attenuate blood pressure. Aberrant filtration of plasminogen and conversion within the urinary space to plasmin may activate ? ENaC proteolytically and contribute to inappropriate NaCl retention and oedema in acute proteinuric conditions and to hypertension in diseases with chronic microalbuminuria/proteinuria. PMID:23216619

Svenningsen, P; Friis, U G; Versland, J B; Buhl, K B; Mller Frederiksen, B; Andersen, H; Zachar, R M; Bistrup, C; Sktt, O; Jrgensen, J S; Andersen, R F; Jensen, B L

2013-03-01

413

Preparation, characterization and electrochemical corrosion studies on environmentally friendly waterborne polyurethane\\/Na +-MMT clay nanocomposite coatings  

Microsoft Academic Search

In this study, we present the first practical evaluation for the corrosion protection effect of waterborne polyurethane (WPU)\\/Na+-montmorillonite (Na+-MMT) clay nanocomposite coating. Typically, a series of waterborne polyurethane (WPU)\\/Na+-montmorillonite (Na+-MMT) clay nanocomposite materials have been successfully prepared by effectively dispersing the inorganic nanolayers of commercially purified Na+-MMT clay in WPU matrix through direct aqueous solution dispersion technique. First of all,

Jui-Ming Yeh; Chia-Tseng Yao; Chi-Fa Hsieh; Li-Hwa Lin; Pei-Li Chen; Jinn-Chern Wu; Hsing-Chung Yang; Chi-Phi Wu

2008-01-01

414

Direct measurement of the masses of 11Li and 26-32Na with an on-line mass spectrometer  

Microsoft Academic Search

The use of an on-line mass spectrometer to make direct mass measurements of short-lived isotopes far from the stability line has been improved to yield more accurate mass measurements for 27-30Na, new mass measurements for 11Li, 31,32Na, and to remove a discrepancy between existing mass measurements of 26Na. The mass excesses (keV) measured are: 11Li, 40940+\\/-80 26Na, -6901+\\/-25 27Na, -5620+\\/-60

C. Thibault; R. Klapisch; C. Rigaud; A. M. Poskanzer; R. Prieels; L. Lessard; W. Reisdorf

1975-01-01

415

A facile route for the preparation of morphology-controlled NaTaO 3 films  

NASA Astrophysics Data System (ADS)

Ternary metal oxide films have being attracting increasing attention because of their special properties and potential applications in many important areas. In this paper, we report a facile hydrothermal route for the preparation of NaTaO 3 thin films on tantalum foils with controlled morphology. In the NaOH solution, the morphology of crystals in the resultant NaTaO 3 film changed from nanocubes to irregular nanoparticles, and then to meshwork of connected nanobranches as the synthesis temperature increased. The evolution of the NaTaO 3 crystal morphology was different when hydrogen peroxide (H 2O 2) was added to the NaOH solution as an oxidizer. In the H 2O 2-added NaOH solution, the resultant NaTaO 3 crystal morphology evolved from nanopyramids to nanoplates, and then to nanospheres with increasing the hydrothermal treatment temperature. The results of this study indicated that the synthesis temperature and the presence of H 2O 2 collaboratively strongly affected the NaTaO 3 particle morphology in the films. The change of the NaTaO 3 particle morphology was explained by the two dissolution-crystallization processes and the Oswald ripening effect.

Zhou, Xingfu; Chen, Ying; Mei, Hua; Hu, Zhaolin; Fan, Yiqun

2008-12-01

416

Organophosphate inhibition of avian salt gland Na, K-ATPase activity.  

PubMed

1. Adult black ducks (Anas rubripes) were given freshwater or saltwater (1.5% NaCl) for 11 days and half of each group was also given an organophosphate (17 p.p.m. fenthion) in the diet on days 6-11. 2. After 11 days, ducks drinking saltwater had lost more weight and had higher plasma Na and uric acid concentrations and osmolalities than birds drinking freshwater. 3. Saltwater treatment stimulated the salt gland to increased weight and Na, K-ATPase activity. 4. Fenthion generally reduced plasma and brain cholinesterase activity and depressed cholinesterase and Na, K-ATPase activities in salt glands of birds drinking saltwater. PMID:6128165

Eastin, W C; Fleming, W J; Murray, H C

1982-01-01

417

Mutant N143P Reveals How Na[superscript +] Activates Thrombin  

SciTech Connect

The molecular mechanism of thrombin activation by Na{sup +} remains elusive. Its kinetic formulation requires extension of the classical Botts-Morales theory for the action of a modifier on an enzyme to correctly account for the contribution of the E*, E, and E:Na{sup +} forms. The extended scheme establishes that analysis of k{sub cat} unequivocally identifies allosteric transduction of Na{sup +} binding into enhanced catalytic activity. The thrombin mutant N143P features no Na{sup +}-dependent enhancement of k{sub cat} yet binds Na{sup +} with an affinity comparable to that of wild type. Crystal structures of the mutant in the presence and absence of Na{sup +} confirm that Pro{sup 143} abrogates the important H-bond between the backbone N atom of residue 143 and the carbonyl O atom of Glu{sup 192}, which in turn controls the orientation of the Glu{sup 192}-Gly{sup 193} peptide bond and the correct architecture of the oxyanion hole. We conclude that Na{sup +} activates thrombin by securing the correct orientation of the Glu{sup 192}-Gly{sup 193} peptide bond, which is likely flipped in the absence of cation. Absolute conservation of the 143-192 H-bond in trypsin-like proteases and the importance of the oxyanion hole in protease function suggest that this mechanism of Na{sup +} activation is present in all Na{sup +}-activated trypsin-like proteases.

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

2010-01-12

418

Physiological Characterization of Two Genes for Na+ Exclusion in Durum Wheat, Nax1 and Nax21  

PubMed Central

Durum wheat (Triticum turgidum L. subsp. durum Desf.) Line 149 contains two novel major genes for excluding Na+ from leaf blades, named Nax1 and Nax2. The genes were separated into families containing a single gene and near-isogenic homozygous lines were selected. Lines containing either Nax1 or Nax2 had lower rates of Na+ transport from roots to shoots than their near-isogenic pairs due to lower rates of net loading of the xylem, not to lower rates of net uptake from the soil or higher rates of retranslocation in the phloem. Nax1 and Nax2 lines also had higher rates of K+ transport from root to shoot, resulting in an enhanced discrimination of K+ over Na+. Lines containing Nax1 differed from those containing Nax2 by unloading Na+ from the xylem as it entered the shoot so that Na+ was retained in the base of the leaf, leading to a high sheath to blade ratio of Na+ concentration. Gradients in tissue concentrations of Na+ along the leaf suggested that Na+ was continually removed from the xylem. The Nax2 line did not retain Na+ in the base of the leaf, suggesting that it functioned only in the root. The Nax2 gene therefore has a similar function to Kna1 in bread wheat (Triticum aestivum). PMID:17028150

James, Richard A.; Davenport, Romola J.; Munns, Rana

2006-01-01

419

The use of Na-22 as a tracer for long-term bone mineral turnover studies.  

NASA Technical Reports Server (NTRS)

Sodium-22 has been studied as a tracer for bone mineral metabolism in rats and dogs. When incorporated into bone during growth from birth to adulthood, the bone becomes uniformly tagged with Na-22, which is released through the metabolic turnover of the bone. The Na-22 not incorporated in the bone matrix is rapidly excreted within a few days when animals are fed high, but nontoxic levels of NaCl. The Na-22 tracer can be used to measure bone mineral loss in animals during space flight and in research on bone disease.

Palmer, H. E.; Rieksts, G. A.; Palmer, R. F.; Gillis, M. F.

1979-01-01

420

CRMP2 Protein SUMOylation Modulates NaV1.7 Channel Trafficking*  

PubMed Central

Voltage-gated sodium channel (NaV) trafficking is incompletely understood. Post-translational modifications of NaVs and/or auxiliary subunits and protein-protein interactions have been posited as NaV-trafficking mechanisms. Here, we tested if modification of the axonal collapsin response mediator protein 2 (CRMP2) by a small ubiquitin-like modifier (SUMO) could affect NaV trafficking; CRMP2 alters the extent of NaV slow inactivation conferred by the anti-epileptic (R)-lacosamide, implying NaV-CRMP2 functional coupling. Expression of a CRMP2 SUMOylation-incompetent mutant (CRMP2-K374A) in neuronal model catecholamine A differentiated (CAD) cells did not alter lacosamide-induced NaV slow inactivation compared with CAD cells expressing wild type CRMP2. Like wild type CRMP2, CRMP2-K374A expressed robustly in CAD cells. Neurite outgrowth, a canonical CRMP2 function, was moderately reduced by the mutation but was still significantly higher than enhanced GFP-transfected cortical neurons. Notably, huwentoxin-IV-sensitive NaV1.7 currents, which predominate in CAD cells, were significantly reduced in CAD cells expressing CRMP2-K374A. Increasing deSUMOylation with sentrin/SUMO-specific protease SENP1 or SENP2 in wild type CRMP2-expressing CAD cells decreased NaV1.7 currents. Consistent with a reduction in current density, biotinylation revealed a significant reduction in surface NaV1.7 levels in CAD cells expressing CRMP2-K374A; surface NaV1.7 expression was also decreased by SENP1 + SENP2 overexpression. Currents in HEK293 cells stably expressing NaV1.7 were reduced by CRMP2-K374A in a manner dependent on the E2-conjugating enzyme Ubc9. No decrement in current density was observed in HEK293 cells co-expressing CRMP2-K374A and NaV1.1 or NaV1.3. Diminution of sodium currents, largely NaV1.7, was recapitulated in sensory neurons expressing CRMP2-K374A. Our study elucidates a novel regulatory mechanism that utilizes CRMP2 SUMOylation to choreograph NaV1.7 trafficking. PMID:23836888

Dustrude, Erik T.; Wilson, Sarah M.; Ju, Weina; Xiao, Yucheng; Khanna, Rajesh

2013-01-01

421

Sodium selenite pentahydrate, Na2SeO35H2O  

PubMed Central

In the crystal structure of Na2SeO35H2O [disodium selenate(IV) pentahydrate], two Se, two selenite O atoms and one water O atom are located on a mirror plane, and one water O atom is located on a twofold rotation axis. The coordination of one Na+ cation is distorted trigonal bipyramidal, formed by three equatorial H2O ligands and two axial selenite O atoms. The other Na+ cation has an octahedral coordination by six water molecules. The two independent SeO3 groups form almost undistorted trigonal pyramids, with SeO bond lengths in the range 1.6856?(7)1.7202?(10)? and OSeO angles in the range 101.98?(3)103.11?(5), and both are ?2-O:O-bonded to a pair of Na+ cations. Hydrogen bonds involving all water molecules and selenite O atoms consolidate the crystal packing. Although anhydrous Na2SeO3 and Na2TeO3 are isotypic, the title compound is surprisingly not isotypic with Na2TeO35H2O. In the tellurite hydrate, all Na+ cations have an octahedral coordination and the TeO3 groups are bonded to Na+ only via one of their three O atoms. PMID:24454013

Mereiter, Kurt

2013-01-01

422

Sodium selenite penta-hydrate, Na2SeO35H2O.  

PubMed

In the crystal structure of Na2SeO35H2O [disodium selen-ate(IV) penta-hydrate], two Se, two selenite O atoms and one water O atom are located on a mirror plane, and one water O atom is located on a twofold rotation axis. The coordination of one Na(+) cation is distorted trigonal bipyramidal, formed by three equatorial H2O ligands and two axial selenite O atoms. The other Na(+) cation has an octa-hedral coordination by six water mol-ecules. The two independent SeO3 groups form almost undistorted trigonal pyramids, with Se-O bond lengths in the range 1.6856?(7)-1.7202?(10)? and O-Se-O angles in the range 101.98?(3)-103.11?(5), and both are ?2-O:O-bonded to a pair of Na(+) cations. Hydrogen bonds involving all water molecules and selenite O atoms consolidate the crystal packing. Although anhydrous Na2SeO3 and Na2TeO3 are isotypic, the tit