Effect Of Na Ions Research Articles

Influence of Wrinkle Structure on Properties of Na-doped ZnO Films

Un-doped ZnO and Na-doped ZnO (NZO) thin films with various Na doping concentrations were successfully fabricated on glass substrates by a sol-gel process. The effect of Na ions at concentrations of 0, 1, 2, 3, 4, and 5% on the crystalline structure, surface morphology, and optoelectronic properties of ZnO films was studied using appropriate measurement techniques. XRD analysis revealed a polycrystalline hexagonal wurtzite structure in the NZO films. The NZO films' average crystal size ranged from 17.7 nm to 19.6 nm. SEM micrographs showed that wrinkle network appeared in the pure and doped ZnO films due to solvent evaporation during the thermal annealing process. UV-Vis spectroscopy pointed out that the average transmittance of NZO films is as large as ca. 78%. The optical bandgap of the films varied slightly between 3.235 eV for the pure ZnO and 3.246 eV for the Na 5% doped NZO film. When Na ions were doped into the NZO films, the electrical conductivity improved. Moreover, the absorption figure of merit exhibited the largest value of 0.981 Ω-1cm-1 for the fabricated NZO films, which enables the use of these films for solar cells and for other optoelectronic applications.

Effect of Na ion on Cu2O:Co nanocrystals and subsequent attributes in structural and optical characteristics

Cuprous oxide-based nanocrystals were synthesized by conventional sol-gel techniques under an ambient environment. Herein, we systematically examined how Na ion influences the optical and structural characteristics of the nanocrystal. The X-ray diffraction exhibits Cu2O and Cu2O:Co nanocrystals have cubic structure (Pn-3m) with average crystallite sizes of 41.70 and 43.00 nm, respectively. Photoluminescence and FT-IR spectra clearly show the existence of CuO phase due to Na, Co doping. HR-TEM micrograph exhibits that the particle size ranges between 0.89–1.11 μm, and that agglomeration diminishes with Na, Co doping concentration. The optical bandgap of Cu2O based nanocrystals were found to be reduced and improves optical absorption in the visible region. Eventually, XPS measurement gives us the existence of several oxidation states of Cu and Co and a single oxidation state of Na.

Effect of Na and Cl Ions on Coercivity of Electroplated Fe-Pt Film-Magnets

Recently, we investigated the effect of Na ion concentration in plating baths on the coercivity of L10 ordered Fe-Pt thick-film magnets prepared by an electroplating method and pointed out that a possibility of enhancement in the coercivity by the Na ion. In the present study, we electroplated Fe-Pt films on Cu substrates from plating baths with various concentrations of the NaCl for obtaining further evidence of the coercivity enhancement, focusing on the L10 ordering process of the film. From an x-ray diffraction analysis, we found that the Δ2θ, which has a diffraction peak split between (002) and (200) of the L10 ordered phase (fct structure), increased with increasing NaCl concentration under the same annealing conditions, and confirmed that the annealed films with large Δ2θ tend to show high coercivity. When varying the amount of NaCl in the plating bath, not only the Na ion concentration but also the Cl ion one varies, suggesting that the Cl ion also has a possibility of coercivity enhancement. In order not to vary the Cl ion concentration, we changed the reagent, which supplies the Na ions into the plating bath, from NaCl to Na2SO4. Consequently, the coercivity of the films for the baths with Na2SO4 (the Na ion) showed higher value compared with those for the baths without Na2SO4. From these results, we concluded that Na ion effectively works to enhance the L10 ordering and the coercivity for the electroplated Fe-Pt thick film-magnets.

Effect of bias voltage application on potential-induced degradation for crystalline silicon photovoltaic modules

To analyze the dynamic behavior of Na ions in the p–n junction of crystalline Si photovoltaic (PV) cells during potential-induced degradation (PID), a bias voltage was applied between the electrodes of the testing PV modules. During the PID test with a negative high voltage stress (HVS), PID was suppressed by the simultaneous loading of a forward bias voltage, although that of a reverse bias voltage accelerated the progression of PID. However, in the recovery stage after the PID test, the opposite loading effects of the bias voltage with a positive HVS were found. In other words, the extent of recovery from PID was suppressed or enhanced by forward or reverse bias loading, respectively. Similar effects of bias loading were observed even under the recovery conditions without the positive HVS. The effect of Na ions within a depletion layer on the evolution of PID will be discussed for the interpretation of these results.

The Effect of Na-Ion on the Growth and Hydrogen Generation of Hydrogen-Producing Bacteria Yuan-3

Hydrogen-producing zymogenous bacteria YUAN-3 (Ethanoligenens harbinense) is used as the study object, on which the intermittent hydrogen production test is applied to examine the influence of Na-ion concentration on the growth and gas generation of YUAN-3. Research results show that when Na ion concentration is 1.5g/L, cell concentration reaches the maximum level 0.892g/L; when Na-ion concentration is maintained at 2.0~3.0g/L, culture medium is applicable for hydrogen generation of YUAN-3.

The Effect of Na-Ion on the Growth and Hydrogen Generation of Hydrogen-Producing Bacteria Yuan-3

Hydrogen-producing zymogenous bacteria YUAN-3 (Ethanoligenens harbinense) is used as the study object, on which the intermittent hydrogen production test is applied to examine the influence of Na-ion concentration on the growth and gas generation of YUAN-3. Research results show that when Na ion concentration is 1.5g/L, cell concentration reaches the maximum level 0.892g/L; when Na-ion concentration is maintained at 2.0~3.0g/L, culture medium is applicable for hydrogen generation of YUAN-3.

The effects of sodium in ITO by pulsed laser deposition on organic light-emitting diodes

The depth profile of ITO on glass was measured by the time-of-flight secondary ion mass spectroscopy (TOFSIMS) which revealed high sodium (Na) ion concentration at the ITO surface as well as at the ITO–glass interface as a result of out diffusion with substrate heating. Effects of Na ions on the performance of organic light-emitting diode (OLED) were studied by etching away a few tens of nanometers off the ITO surface with a dilute aquaregia solution of HNO3:HCl:H2O. A single-layer, molecularly doped ITO/(PVK+TPD+Alq3)/Al OLEDs were fabricated on bare and etched ITO samples. Although the removal of a 10-nm layer of ITO surface increased the voltage range, brightness, and lifetime, it was insufficient to correlate these improvements with solely to the Na ion reduction without considering the surface roughness.

Fermi Surface Topology of Na0.5CoO2 from the HybridDensity Functional

The Fermi surface topology of Na0.5CoO2 is studied using thehybrid density functional theory. We first study a single(CoO2)0.5− layer model with the percentage of thenonlocal Hartree–Fock exchange changing from 0% to 20%. The resultsshow that only when the mixed nonlocal Hartree–Fock exchange isbetween 1% and 5%, the Fermi surface topology is similar to theexperimental one. With 3% HF exchange in the hybrid densityfunctional, considering the effects of Na ions in theNa0.5CoO2 system, we find that the Fermi surface is splitto double holes and small gaps open near the intersections between theBrillouin zone and the Fermi surface. Our results show that both theamounts of the nonlocal Hartree–Fock exchange in the hybrid densityfunctional and the Na ions have much influence on the Fermi surfacetopology.

Sodium dependency of the photosynthetic electron transport in the alkaliphilic cyanobacterium Arthrospira platensis.

Arthrospira (Spirulina) platensis (A. platensis) is a model organism for investigation of adaptation of photosynthetic organisms to extreme environmental conditions: the cell functions in this cyanobacterium are optimized to high pH and high concentration (150-250 mM) of Na+. However, the mechanism of the possible fine-tuning of the photosynthetic functions to these extreme conditions and/or the regulation of the cellular environment to optimize the photosynthetic functions is poorly understood. In this work we investigated the effect of Na-ions on different photosynthetic activities: linear electron transport reactions (measured by means of polarography and spectrophotometry), the activity of photosystem II (PS II) (thermoluminescence and chlorophyll a fluorescence induction), and redox turnover of the cytochrome b6f complex (flash photolysis); and measured the changes of the intracellular pH (9-aminoacridine fluorescence). It was found that sodium deprivation of cells in the dark at pH 10 inhibited, within 40 min, all measured photosynthetic reactions, and led to an alkalinization of the intracellular pH, which rose from the physiological value of about 8.3-9.6. These were partially and totally restored by readdition of Na-ions at 2.5-25 mM and about 200 mM, respectively. The intracellular pH and the photosynthetic functions were also sensitive to monensin, an exogenous Na+/H+ exchanger, which collapses both proton and sodium gradients across the cytoplasmic membrane. These observations explain the strict Na+-dependency of the photosynthetic electron transport at high extracellular pH, provide experimental evidence on the alkalization of the intracellular environment, and support the hypothesized role of an Na+/H+ antiport through the plasma membrane in pH homeostasis (Schlesinger et al. (1996). J. Phycol. 32, 608-613). Further, we show that (i) the specific site of inactivation of the photosynthetic electron transport at alkaline pH is to be found at the water splitting enzyme; (ii) in contrast to earlier reports, the inactivation occurs in the dark and, for short periods, without detectable damage in the photosynthetic apparatus; and (iii) in contrast to high pH, Na+ dependency in the neutral pH range is shown not to originate from PSII, but from the acceptor side of PSI. These data permit us to conclude that the intracellular environment rather than the machinery of the photosynthetic electron transport is adjusted to the extreme conditions of high pH and high Na+ concentration.

The effects of Na ions on the properties of calcined rare-earths Y (CREY) zeolites

FTIR spectroscopy of pyridine thermal desorption, nitrogen sorption, powder X-ray diffraction (XRD), together with elemental analysis have been used to study the physicochemical properties of a family of rare earth (RE) containing faujasite (REY) crystals having different composition, unit cell dimension, acidity and hydrothermal stability (at 760°C with 100% steam, 1 atm). The calcined REY (CREY) was prepared by ion-exchanging Na ions in NH 4Y with a mixture of RE chlorides prepared by acid-leaching bastneasite. At 70°C, a 2M NH 4NO 3 solution can reduce the CREY Na 2O level from 3.3% to 0.41% in only 1 h and after an intermediate calcination step at 500°C/h, a second ion-exchange reaction can further reduce the Na 2O level to 0.06% without severely affecting crystals properties. De-alumination after the intermediate calcination step, is believed responsible for minor losses of La and for unit cell contraction. The selective removal of framework of Na ions, change the distribution of Bronsted ( B) and Lewis ( L) acid sites as well as acid site strength. In CREY with 3.3% Na 2O, acidity is mainly of the B-type and at 200°C the B/ L ratio is 21.1. The B/ L ratio monotonically decreases to 4.36 from 21.1 when the %Na 2O decreases to 0.06% from 3.30% and the crystals's Si/Al molar ratio increases to 2.83 from 2.38. Acidity, hydrothermal stability and resistance to vanadium deactivation in CREY crystals having Si/Al=2.83 and containing trace amounts of Na, are similar to those observed for silicon-enriched HY with Si/Al in the 5.0–10.0 range.

PEIERLS PHASE TRANSITION AND NONLINEAR TRANSPORT STUDY OF DOPED BLUE BRONZES K0.3-xNaxMoO3

Temperature dependence of Ohmic resistance, and nonlinear current–voltage (I–V) characteristics at 77 K were systematically studied in pure potassium blue bronze K 0.3 MoO 3 and Na-doped alloy bronzes K 0.3-x Na x MoO 3(x = 0.02, 0.05, 0.10). No considerable influence of Na ions doping in K 0.3 MoO 3 was found on the Peierls transition temperature, while obvious enchancement on semiconductor gap and remarkable influence on the first threshold field were observed. We attribute the first phenomenon to two opposite effects of Na ions, and the depinning model is proposed to account for the latter. The analytical form of nonlinear charge-density wave current I CDW in a moderate field range fits the power-law relation, i.e. I CDW ∝ (V/V T -1)α, where the exponent α is about 3/2 and slightly enhanced by Na ions doping.

Stress and salt intake: experimental data on Dahl salt­resistant and salt­sensitive rats

The objective of the study was to evaluate the susceptibility of genetically predisposed to salt sensitivity Dahl rats to psychological stress and the effect of sodium ion on stress development. After weaning, Dahl salt-resistant (DR) and two groups of salt-sensitive (DS) rats were fed low-Na (0.5 per cent NaCI) and high-Na (8 per cent NaCI) diets for 2 months. A constellation of sensorimotor and behavioural tests were employed. The psychological stress was produced using a new model of acoustic startle device. DS weanling rats showed significantly increased sensorimotor reactivity, increased emotionality and increased sensitivity to acoustic stress, as compared to DR weanling rats. All the above parameters were exaggerated after 2-month Na loading: there was a significant decrease in the latency of the stressful response and increased magnitude of the hypertensive response to auditory stress. Blood pressure of Na-loaded DS rats increased by 43 per cent after auditory stress, as compared to 18 per cent increase in the Na-restricted rats. The effect of Na ion was mediated by an increased activity of the sympathetic nervous system (SNS). The chronic effect of Na restriction showed reduced SNS responsiveness and diminished neurohumoral reserve to maintain cardiovascular homeostasis. Risks of both Na loading and Na depletion in sodium sensitivity were discussed.

Thermal characterization of commercial alumina with different preparation histories by emanation thermal analysis using Ra-226 parent isotope

Emanation thermal analysis (ETA) using the Ra-226 parent isotope, was applied in the range 25–1450°C for the characterization of commerical alumina powders with various preparation histories. The gas-release stages in the ETA curves for α-alumina prepared by a Bayer process were broadly grouped into two parts: peak I maximizing at 100–550 °C (Ia at about 270–300°C and Ib at 450–500°C) and peak II starting at about 800°C (IIa maximizing at 950°C and IIb at about 1200°C). The effects of Na ions, heating and grinding on the ETA behaviors were discussed.