Detection Of Na Research Articles

Low-temperature aqueous alteration of crystalline pyrochlore: correspondence between nature and experiment

AbstractPyrochlore has been considered as a waste form to immobilize high-level nuclear waste such as excess weapons-grade plutonium. In order to study the aqueous stability of pyrochlore, we have carried out hydrothermal experiments with a natural microlite (Nb + Ta > 2Ti; Ta ⩾ Nb) at 175°C in a neutral and acidic solution for 14 days. The starting material and the experimental products were studied by electron microprobe, backscattered electron (BSE) imaging, powder infrared (IR) and micro-Raman spectroscopy, and powder X-ray diffractrometry (XRD). The microlite has small U (∼200 ppm) and Th (∼800 ppm) contents and is crystalline. The hydrothermal treatment in a solution containing l mol/l HCl and l mol/l CaCl2 causes the partial replacement of the microlite (up to ∼10 μm) by a new pyrochlore phase. This new phase is characterized by a larger unit-cell volume and contains a large number of vacancies at the A site (A = Ca, Na) as well as anion vacancies, molecular water, and possibly OH groups. Analyses of the experimental fluid further revealed that U was also selectively lost to the solution. Treatment in pure water did not produce reaction zones detectable by BSE imaging or powder XRD. However, significant spectral changes in powder IR spectra of the reaction product and the detection of Na and Ca in the solution indicate that the microlite has also reacted in pure water. The experimental alteration features bear a remarkable resemblance to those seen in naturally altered microlite samples, suggesting that short-term experimental results can be applied to natural systems and vice versa in order to evaluate the long-term stability of a pyrochlore waste form.

Effect of salt stress on growth and cation compartmentation in leaves of two plant species differing in salt tolerance

Salinity can cause toxic symptoms, especially in mature leaves after long-term exposure. Thus, Na+ accumulation in leaves could be responsible for salt toxicity. The infiltration-centrifugation technique was employed for the isolation of apoplastic washing fluids (AWF) from leaves and the detection of Na+, K+ and Ca2+ was carried out by ion chromatography. The Na+ concentrations in the leaf apoplast of salt-sensitive corn and salt-tolerant cotton plants significantly increased with higher Na+ supply. Nevertheless, the apoplastic Na+ concentration did not exceed 10 and 30 mmol/L, respectively, after salt exposure up to 150 mmol/L in the medium in short- and long-term salt treatments. Higher Na+ concentrations were found in the leaf apoplast of salt-tolerant cotton in comparison to those of salt-sensitive corn, particularly in fully expanded leaves. No bound Na+ was found in the leaf apoplast. The Na+ concentration in the leaf apoplast did not reach high enough concentrations to be responsible for the decline in leaf growth under salinity. Supplemental Ca2+ did not affect Na+ concentration in the leaf apoplast under salinity. Apoplastic Ca2+ concentration remained constant, while K+ concentrations increased in the leaf apoplast under salinity. Our results do not support the hypothesis by Oertli (1968) who proposed that salt accumulation in the leaf apoplast could be responsible for the death of leaves in plants exposed to salinity.

Simultaneous determination of Pseudomonas aeruginosa elastase, human leukocyte elastase and cathepsin G activities by micellar electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC) is a new method for analysing proteolytic activities simultaneously present in incubation mixtures. Here we demonstrate that MEKC differentiates between the enzymatic activities of Pseudomonas aeruginosa elastase (PsE) and human leukocyte elastase (HLE) or cathepsin G (Cat G) in assays using the chromogenic peptide substrates Suc–Ala–Ala–Ala–NA or Suc–Ala–Ala–Pro–Phe–NA, respectively (where Suc=succinyl and NA=4-nitroaniline/u-nitroanilide). When PsE and Cat G were incubated at equimolar ratio with Suc–Ala–Ala–Pro–Phe–NA, the PsE-specific cleavage products PheNA and Suc–Ala–Ala–Pro were detected whereas inhibition of the metalloproteinase PsE with EDTA resulted in detection of NA and Suc–Ala–Ala–Pro–Phe only. Similarly, when PsE and HLE were incubated at equimolar ratio with Suc–Ala–Ala–Ala–NA, the PsE-specific cleavage products Suc–Ala and Ala–Ala–NA were detected whereas at an PsE-HLE ratio 1:50, both the PsE-specific and the HLE-specific cleavage products NA and Suc–Ala–Ala–Ala were separated. MEKC also allowed determination of the kinetic constants for the interactions of PsE, Cat G and HLE with the substrates considered.

Electrochemical microsensor for the detection of Na+ ions

Abstract Thin vitreous films were elaborated by microelectronic techniques (vacuum evaporation, r.f. sputtering) and structural and electrical properties were characterized respectively by X-ray diffractometry and complex impedance spectroscopy measurements. Morphology and composition of thin films were examined by scanning electron microscopy with energy dispersive spectroscopic microprobe. Based on these thin films, Na + -selective microsensors were built up with a sodium aluminosilicate glass as the sensitive membrane and thin film of borophosphate as the ionic bridge acting as an interfacial layer providing an ionic and electronic exchange between the collector and the sensitive membrane. Electrochemical behaviour and sensitivity results regarding the microsensor were investigated. Microsensors exhibit near-Nerstian response in the Na + -concentration range of 10 −1 –10 −4 mol/l with a detection limit close to 5 × 10 −4 M and good reproducibility.

Interstellar gas phase abundance of carbon, oxygen, nitrogen, copper, gallium, germanium, and krypton toward Zeta Ophiuchi

An analysis of weak (less than 10 mA) UV interstellar absorption line data obtained for the line of sight to the O9.5 IV star Zeta Oph is presented. Measurements of weak semiforbidden lines of N I, O I, Cu II, and a new UV detection of Na I are reported along with a small upper limit for C II. Interstellar detections of Ga II, Ge II, and Kr I are also presented. Ga, Ge, and Kr represent the heaviest elements detected in the ISM. A comparison of the derived column densities to cosmic abundances shows Ga to be depleted by about -1.2 dex while Ge is overabundant by +0.2 dex. Assuming Kr to be undepleted, a logarithmic cosmic abundance of Kr/H = 2.95 is obtained on the scale where H = 12.00.

Detection of Na +/H + exchanger mRNA in human neutrophils and lymphocytes using the polymerase chain reaction

Using the reverse polymerase chain reaction (RT-PCR), we have examined the expression of Na +/H + exchanger mRNA in human buffy coat preparations, lymphocytes and neutrophils. Total RNA from all cell types was reverse transcribed specifically and then amplified by PCR. The identity of the PCR products was confirmed by restriction enzyme analysis and hybridization with a specific oligonucleotide probe. The detection or low abundance Na +/H + antiporter specific transcripts by RT-PCR in different human blood cells ex vivo should facilitate future studies on regulatory and pathophysiological aspects of Na +/H + exchanger mRNA expression in human cells and tissue samples.

Expression of amino acid transport systems in cultured human umbilical vein endothelial cells.

1. Nutrient transport in cultured human umbilical vein endothelial cells was characterized using a rapid dual-isotope dilution technique. Microcarrier beads with confluent endothelial cells were perfused in small columns, and uptake and efflux were assessed relative to D-mannitol (extracellular tracer) during a single transit through the column. 2. At tracer concentrations significant unidirectional uptakes were measured for L-leucine (53 +/- 2%), L-phenylalanine (73 +/- 2%), L-serine (40 +/- 4%), L-arginine (42 +/- 3%) and L-ornithine (26 +/- 3%). Uptake for L-proline, D-glucose, dopamine and serotonin was lower (6-10%), whereas uptake for the system A analogue 2-methylaminoisobutyric acid (2-MeAIB) was negligible. Uptakes rapidly decreased with time due to tracer efflux. 3. Endothelial cell transport of L-leucine was markedly inhibited during perfusion with 1 mM-BCH (beta-2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid, system L analogue), L-leucine, D-leucine, L-phenylalanine, L-methionine and L-DOPA. 2-MeAIB, L-cysteine, glycine, L-proline, hydroxy-L-proline, L-aspartate and beta-alanine were poor inhibitors, while L-serine and the cationic substrates L-lysine and L-arginine inhibited uptake by 10-35%. 4. When the kinetics of L-leucine transport were examined over a wide range of substrate concentrations (0.025-1 mM) transport was saturable. A single entry site analysis gave a half-maximal saturation constant Kt = 0.24 +/- 0.08 mM (mean +/- S.E.M., n = 5) and a Vmax = 27.8 +/- 4.6 nmol/min per column (approximately 3 x 10(6) cells). 5. Removal of sodium from the perfusate inhibited tracer uptake of L-leucine, L-serine and L-arginine by respectively 20 +/- 5% (n = 3), 77 +/- 5% (n = 3) and 35 +/- 4% (n = 3). 6. Our results provide the first evidence that cultured human endothelial cells of venous origin express a saturable transport system for large neutral amino acids resembling system L described in brain microvascular endothelium. Detection of Na+-dependent and Na+-independent L-arginine uptake is of interest in view of recent reports that this cationic amino acid may be the physiological precursor for nitric oxide released by endothelium.

Detection of Na, K-ATPase α2 and α3 subunits in rat brain by [formula omitted] hybridization

Detection of Na, K-ATPase α2 and α3 subunits in rat brain by [formula omitted] hybridization

Detection of Na +/K + adenosine triphosphatase messenger RNA in preimplantation rabbit and mouse blastocysts

Detection of Na +/K + adenosine triphosphatase messenger RNA in preimplantation rabbit and mouse blastocysts

Detection of Na+ and K+ in the Rat Adrenal Cortex with the Electron Microprobe

1. In order to demonstrate whether modification of aldosterone secretion is mediated by parallel changes of K+ in the adrenal zona glomerulosa, the total (intracellular+extracellular) Na+ and K+ content of the rat adrenal cortex was determined with the electron microprobe. 2. Groups of rats were submitted to one of the following dietary regimens: standard, low Na+, high K+ or high Na+. 3. Distribution of Na+ and K+ across the zona glomerulosa and zona fasciculata was compared. Standards of known electrolyte concentration were also analysed. 4. The [Na+] was found to be greater in the zona glomerulosa than in the zona fasciculata but K+ was distributed evenly in both zones. This was independent of dietary regimen. 5. Aldosterone production, assessed by plasma aldosterone concentrations, could not be correlated with zona glomerulosa K+ content.

Presence of sodium-potassium-stimulated ATPase in boar epididymal spermatozoon.

SINCE Skou1 reported that an adenosine triphosphatase (ATPase) stimulated by sodium and potassium in the presence of magnesium (Na–K ATPase) is present in submicroscopic fraction of crab nerve, many investigators have reported the presence of the same ATPase in various tissues2–6 (see also Hokin and Hokin's recent review7), and it was suggested that it plays an important part in the process of active transport of potassium and sodium ions. However, information concerning the presence of such an ATPase in spermatozoa is not, as yet, available. It seems very likely that active ion transport mechanism is also present in the spermatozoon, as its motility is affected by ionic environment. This communication reports our detection of Na–K ATPase activity in boar epididymal spermatozoon.