Fast and accurate determination of K, Ca, and Mg in human serum by sector field ICP-MS.

PubMed

Yu, Lee L; Davis, W Clay; Nuevo Ordonez, Yoana; Long, Stephen E

2013-11-01

Electrolytes in serum are important biomarkers for skeletal and cellular health. The levels of electrolytes are monitored by measuring the Ca, Mg, K, and Na in blood serum. Many reference methods have been developed for the determination of Ca, Mg, and K in clinical measurements; however, isotope dilution thermal ionization mass spectrometry (ID-TIMS) has traditionally been the primary reference method serving as an anchor for traceability and accuracy to these secondary reference methods. The sample matrix must be separated before ID-TIMS measurements, which is a slow and tedious process that hindered the adoption of the technique in routine clinical measurements. We have developed a fast and accurate method for the determination of Ca, Mg, and K in serum by taking advantage of the higher mass resolution capability of the modern sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). Each serum sample was spiked with a mixture containing enriched (44)Ca, (26)Mg, and (41)K, and the (42)Ca(+):(44)Ca(+), (24)Mg(+):(26)Mg(+), and (39)K(+):(41)K(+) ratios were measured. The Ca and Mg ratios were measured in medium resolution mode (m/Δm ≈ 4 500), and the K ratio in high resolution mode (m/Δm ≈ 10 000). Residual (40)Ar(1)H(+) interference was still observed but the deleterious effects of the interference were minimized by measuring the sample at K > 100 ng g(-1). The interferences of Sr(++) at the two Ca isotopes were less than 0.25 % of the analyte signal, and they were corrected with the (88)Sr(+) intensity by using the Sr(++):Sr(+) ratio. The sample preparation involved only simple dilutions, and the measurement using this sample preparation approach is known as dilution-and-shoot (DNS). The DNS approach was validated with samples prepared via the traditional acid digestion approach followed by ID-SF-ICP-MS measurement. DNS and digested samples of SRM 956c were measured with ID-SF-ICP-MS for quality assurance, and the results (mean �

Na+/Ca2+ exchange and Na+/K+-ATPase in the heart

PubMed Central

Shattock, Michael J; Ottolia, Michela; Bers, Donald M; Blaustein, Mordecai P; Boguslavskyi, Andrii; Bossuyt, Julie; Bridge, John H B; Chen-Izu, Ye; Clancy, Colleen E; Edwards, Andrew; Goldhaber, Joshua; Kaplan, Jack; Lingrel, Jerry B; Pavlovic, Davor; Philipson, Kenneth; Sipido, Karin R; Xie, Zi-Jian

2015-01-01

This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field. PMID:25772291

The existence and stability of the anions matching the MFk+2- formula (M = Li, Na, K, Be, Mg, Ca, B, Al, Ga)

NASA Astrophysics Data System (ADS)

Marchaj, Marzena; Freza, Sylwia; Skurski, Piotr

2013-02-01

The electronic stabilities of the MFk+2- anions (where M = Li, Na, K, Be, Mg, Ca, B, Al, Ga; and k is the maximal formal valence of atom M) were investigated at the OVGF/6-311 + G(3df) level. The vertical electron detachment energies (VDE) of the anions examined were found to be large (7.1-10.1 eV) albeit not significantly exceeding those for the corresponding MFk+1- superhalogen anions. Even though all the MFk+2- species studied were predicted to be both geometrically and electronically stable, some of them turned out to be thermodynamically unstable (i.e., susceptible to the F atom loss).

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

NASA Astrophysics Data System (ADS)

Jakymiw, Clément; Vočadlo, Lidunka; Dobson, David P.; Bailey, Edward; Thomson, Andrew R.; Brodholt, John P.; Wood, Ian G.; Lindsay-Scott, Alex

2018-04-01

ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth's deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure ( Cmcm; commonly referred to as the "post-perovskite" structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 ( P63/ mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 ( P21/ m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/ mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2

High-temperature properties of (La,Ca)(Fe,Mg,Mo)O3-δ perovskites as prospective electrode materials for symmetrical SOFC

NASA Astrophysics Data System (ADS)

Istomin, S. Ya.; Morozov, A. V.; Abdullayev, M. M.; Batuk, M.; Hadermann, J.; Kazakov, S. M.; Sobolev, A. V.; Presniakov, I. A.; Antipov, E. V.

2018-02-01

La1-yCayFe0.5+x(Mg,Mo)0.5-xO3-δ oxides with the orthorhombic GdFeO3-type perovskite structure have been synthesized at 1573 K. Transmission electron microscopy study for selected samples shows the coexistence of domains of perovskite phases with ordered and disordered B-cations. Mössbauer spectroscopy studies performed at 300 K and 573 K show that while compositions with low Ca-content (La0.55Ca0.45Fe0.5Mg0.2625Mo0.2375O3-δ and La0.5Ca0.5Fe0.6Mg0.175Mo0.225O3-δ) are nearly oxygen stoichiometric, La0.2Ca0.8Fe0.5Mg0.2625Mo0.2375O3-δ is oxygen deficient with δ ≈ 0.15. Oxides are stable in reducing atmosphere (Ar/H2, 8%) at 1173 K for 12 h. No additional phases have been observed at XRPD patterns of all studied perovskites and Ce1-xGdxO2-x/2 electrolyte mixtures treated at 1173-1373K, while Fe-rich compositions (x≥0.1) react with Zr1-xYxO2-x/2 electrolyte above 1273 K. Dilatometry studies reveal that all samples show rather low thermal expansion coefficients (TECs) in air of 11.4-12.7 ppm K-1. In reducing atmosphere their TECs were found to increase up to 12.1-15.4 ppm K-1 due to chemical expansion effect. High-temperature electrical conductivity measurements in air and Ar/H2 atmosphere show that the highest conductivity is observed for Fe- and Ca-rich compositions. Moderate values of electrical conductivity and TEC together with stability towards chemical interaction with typical SOFC electrolytes make novel Fe-containing perovskites promising electrode materials for symmetrical solid oxide fuel cell.

A powder neutron diffraction study of the crystal structure of the fluoroperovskite NaMgF3 (neighborite) from 300 to 3.6 K

NASA Astrophysics Data System (ADS)

Mitchell, Roger H.; Alexander, Malcolm; Cranswick, Lachlan M. D.; Swainson, Ian P.

2007-12-01

The cell dimensions and crystal structures of the fluoroperovskite NaMgF3 (neighborite), synthesized by solid state methods, have been determined by powder neutron diffraction and Rietveld refinement over the temperature range 300 3.6 K using Pt metal as an internal standard for calibration of the neutron wavelength. These data show that Pbnm NaMgF3 does not undergo any phase transitions to structures of lower symmetry with decreasing temperature. The cell dimensions and atomic coordinates together with polyhedron volumes and distortion indices are given for Pbnm NaMgF3 at 25 K intervals from 300 to 3.6 K. Decreases in the a and c cell dimensions reach a saturation point at 50 K, whereas the b dimension becomes saturated at 150 K. The distortion of the structure of Pbnm NaMgF3 from the aristotype cubic Pmifmmodeexpandafterbarelseexpandafter\\=fi{3}m structure is described in terms of the tilting of the MgF6 octahedra according to the tilt scheme a - a - c + . With decreasing temperature the antiphase tilt ( a -) increases from 14.24° to 15.39°, whereas the in-phase tilt ( c + ) remains effectively constant at ˜10.7°. Changes in the tilt angles are insufficient to cause changes in the coordination sphere of Na that might induce a low temperature phase transition. The structure of Pbnm NaMgF3 is also described in terms of normal mode analysis and displacements of the condensed normal modes are compared with those of Pbnm KCaF3.

Luminescence characteristics of Dy3+ activated Na 2Sr 2Mg (BO 3)2F 2: Dy 3+ phosphor

NASA Astrophysics Data System (ADS)

Wani, Javaid A.; Dhoble, N. S.; Dhoble, S. J.

2012-11-01

In this paper, we have reported a new Na 2Sr 2Mg (BO 3)2F 2:Dy 3+ thermoluminescence (TL) phosphor prepared via the wet chemical method. Prepared phosphor was characterized by X-ray powder diffraction, photoluminescence (PL), TL and scanning electronmicroscopy techniques. The scanning electronmicroscopic image of Na 2Sr 2Mg (BO 3)2F 2:Dy 3+ phosphor confirms the micron size of particles. Under the PL study, the characteristic emission spectrum of Dy 3+ corresponding to 4F 9/2→6H 15/2 (481 nm) and 4F 9/2→6H 13/2 (576 nm) transitions was observed. The TL property of the as prepared phosphor was also found to be good. TL intensity of Na 2Sr2Mg(BO 3)F 2:Dy 3+ phosphors at 0.99 kGy exposure of γ-irradiations was compared with standard CaSO 4:Dy phosphor. It was seen that TL intensity of Na 2Sr 2Mg (BO 3)2F 2: Dy 3+ phosphors is 1.1 times less compared with the standard CaSO 4:Dy TL dosimeter phosphor. The kinetic parameters are also discussed in detail. The values of activation energy E (eV) and frequency factor S (s -1) were found to be 0.57 eV and 1.25×106 s-1, respectively.

High-pressure transitions of diopside and wollastonite: phase equilibria and thermochemistry of CaMgSi 2O 6, CaSiO 3 and CaSi 2O 5-CaTiSiO 5 system

NASA Astrophysics Data System (ADS)

Akaogi, M.; Yano, M.; Tejima, Y.; Iijima, M.; Kojitani, H.

2004-06-01

Phase transitions of CaMgSi 2O 6 diopside and CaSiO 3 wollastonite were examined at pressures to 23 GPa and temperatures to 2000 °C, using a Kawai-type multiavil apparatus. Enthalpies of high-pressure phases in CaSiO 3 and in the CaSi 2O 5-CaTiSiO 5 system were also measured by high-temperature calorimetry. At 17-18 GPa, diopside dissociates to CaSiO 3-rich perovskite + Mg-rich (Mg,Ca)SiO 3 tetragonal garnet (Gt) above about 1400 °C. The solubilities of CaSiO 3 in garnet and MgSiO 3 in perovskite increase with temperature. At 17-18 GPa below about 1400 °C, diopside dissociates to Ca-perovskite + β-Mg 2SiO 4 + stishovite. The Mg, Si-phases coexisting with Ca-perovskite change to γ-Mg 2SiO 4 + stishovite, to ilmenite, and finally to Mg-perovskite with increasing pressure. CaSiO 3 wollastonite transforms to the walstromite structure, and further dissociates to Ca 2SiO 4 larnite + CaSi 2O 5 titanite. The latter transition occurs at 9-11 GPa with a positive Clapeyron slope. At 1600 °C, larnite + titanite transform to CaSiO 3 perovskite at 14.6±0.6 GPa, calibrated against the α-β transition pressure of Mg 2SiO 4. The enthalpies of formation of CaSiO 3 walstromite and CaSi 2O 5 titanite from the mixture of CaO and SiO 2 quartz at 298 K have been determined as -76.1±2.8, and -27.8±2.1 kJ/mol, respectively. The latter was estimated from enthalpy measurements of titanite solid solutions in the system CaSi 2O 5-CaTiSiO 5, because CaSi 2O 5 titanite transforms to a triclinic phase upon decompression. The enthalpy difference between titanite and the triclinic phase is only 1.5±4.8 kJ/mol. Using these enthalpies of formation and those of larnite and CaSiO 3 perovskite, the transition boundaries in CaSiO 3 have been calculated. The calculated boundaries for the wollastonite-walstromite-larnite + titanite transitions are consistent with the experimental determinations within the errors. The calculated boundary between larnite + titanite and Ca-perovskite has a slope of

Interpretation of Na-K-Mg relations in geothermal waters

USGS Publications Warehouse

Fournier, R.O.

1990-01-01

When using a Na-K-???Mg triangular diagram as an aid in the interpretation of a geothermal water, the estimated temperature of last water-rock equilibration may change by as much as 50??C, depending on which of the many Na/K geothermometers one assumes is correct. A particular geothermometer may work well in one place and not in another because of differences in the mineralogy of the phases that are in contact with the reservoir fluid. The position of the full equilibrium line that is used for geothermometry and for assessing degrees of departure from equilibrium also changes as the assumed K/???Mg geothermometer equation changes. The degree of ambiguity can be evaluated by utilizing the results of all the recently published Na/K geothermometers on a single Na-K-???Mg triangular plot.

A study on alkaline heat treated Mg-Ca alloy for the control of the biocorrosion rate.

PubMed

Gu, X N; Zheng, W; Cheng, Y; Zheng, Y F

2009-09-01

To reduce the biocorrosion rate by surface modification, Mg-Ca alloy (1.4wt.% Ca content) was soaked in three alkaline solutions (Na(2)HPO(4), Na(2)CO(3) and NaHCO(3)) for 24h, respectively, and subsequently heat treated at 773K for 12h. Scanning electron microscopy and energy-dispersive spectroscopy results revealed that magnesium oxide layers with the thickness of about 13, 9 and 26microm were formed on the surfaces of Mg-Ca alloy after the above different alkaline heat treatments. Atomic force microscopy showed that the surfaces of Mg-Ca alloy samples became rough after three alkaline heat treatments. The in vitro corrosion tests in simulated body fluid indicated that the corrosion rates of Mg-Ca alloy were effectively decreased after alkaline heat treatments, with the following sequence: NaHCO(3) heated<Na(2)HPO(4) heated<Na(2)CO(3) heated. The cytotoxicity evaluation revealed that none of the alkaline heat treated Mg-Ca alloy samples induced toxicity to L-929 cells during 7days culture.

The Density and Compressibility of BaCO3-SrCO3-CaCO3-K2CO3-Na2CO3-Li2CO3 Liquids: New Measurements and a Systematic Trend with Cation Field Strength

NASA Astrophysics Data System (ADS)

Hurt, S. M.; Lange, R. A.; Ai, Y.

2015-12-01

The volumetric properties of multi-component carbonate liquids are required to extend thermodynamic models that describe partial melting of the deep mantle (e.g. pMELTS; Ghiorso et al., 2003) to carbonate-bearing lithologies. Carbonate in the mantle is an important reservoir of carbon, which is released to the atmosphere as CO2 through volcanism, and thus contributes to the carbon cycle. Although MgCO3 is the most important carbonate component in the mantle, it is not possible to directly measure the 1-bar density and compressibility of MgCO3 liquid because, like other alkaline-earth carbonates, it decomposes at a temperature lower than its melting temperature. Despite this challenge, Liu and Lange (2003) and O'Leary et al. (2015) showed that the one bar molar volume, thermal expansion and compressibility of the CaCO3 liquid component could be obtained by measuring the density and sound speeds of stable liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system at one bar. In this study, this same strategy is employed on SrCO3- and BaCO3-bearing alkali carbonate liquids. The density and sound speed of seven liquids in the SrCO3-Li2CO3-Na2CO3-K2CO3 quaternary and three liquids in the BaCO3-Li2CO3-Na2CO3-K2CO3 quaternary were measured from 739-1367K, with SrCO3 and BaCO3 concentrations ranging from 10-50 mol%. The density measurements were made using the double-bob Archimedean method and sound speeds were obtained with a frequency-sweep acoustic interferometer. The molar volume and sound speed measurements were used to calculate the isothermal compressibility of each liquid, and the results show the volumetric properties mix ideally with composition. The partial molar volume and compressibility of the SrCO3 and BaCO3 components are compared to those obtained for the CaCO3 component as a function of cation field strength. The results reveal a systematic trend that allows the partial molar volume and compressibility of the MgCO3 liquid component to be estimated.

Tetragonal Almandine, (Fe,Mg,Ca,Na)3(Al,Si,Mg)2Si3O12, a New High-Pressure Mineral from the Shergotty Impact on Mars: an Integrated FESEM-EPMA-Synchrotron Diffraction Investigation

NASA Astrophysics Data System (ADS)

Ma, C.; Tschauner, O. D.

2016-12-01

The combination of FESEM-EDS-EBSD, EPMA, and synchrotron microdiffraction is developing into a powerful tool for identification of micron-scale minerals in rocks such as high-pressure phases in shocked meteorites. During a nanomineralogy investigation of the Shergotty meteorite using this approach, we have identified a new shock-induced high-pressure silicate, majoritic almandine with a tetragonal I41/a structure, in an impact melt pocket. The Shergotty meteorite, which fell in the Gaya district, Bihar, India in 1865, is a Martian basaltic shergottite with shock features. Tetragonal almandine in Shergotty occurs as aggregates of subhedral crystals, 0.8 - 2.5 µm in diameter, along with stishovite in the central region of a shock melt pocket, showing an empirical formula of (Fe1.16Ca0.75Mg0.61Na0.42Mn0.03K0.01)(Al1.16Si0.63Mg0.19Ti0.02)Si3O12. Its general formula is (Fe,Mg,Ca,Na)3(Al,Si,Mg)2Si3O12. EBSD indicated this phase has a garnet-related structure. Synchrotron X-ray diffraction revealed that this garnet has actually a tetragonal structure (I41/a) with unit cell dimensions: a = 11.585(9) Å, c = 11.63(4) Å, V = 1561(7) Å3, and Z = 8. Tetragonal almandine is the polymorph of cubic almandine, a new high-pressure garnet mineral, formed by shock metamorphism via the Shergotty impact event on Mars. It apparently crystallized from Fe-rich shock-induced melt under high-pressure and high-temperature conditions.

First-Principles Study of Chemical Mixtures of CaCl2 and MgCl2 Hydrates for Optimized Seasonal Heat Storage

PubMed Central

2017-01-01

Chloride-based salt hydrates form a promising class of thermochemical materials (TCMs), having high storage capacity and fast kinetics. In the charging cycles of these hydrates however hydrolysis might appear along with dehydration. The HCl produced during the hydrolysis degrades and corrodes the storage system. Our GGA-DFT results show that the enthalpy charge during proton formation (an important step in hydrolysis) is much higher for CaCl2·2H2O (33.75 kcal/mol) than for MgCl2·2H2O (19.55 kcal/mol). This is a strong indicator that hydrolysis can be minimized by appropriate chemical mixing of CaCl2 and Mg Cl2 hydrates, which is also confirmed by recent experimental studies. GGA-DFT calculations were performed to obtain and analyze the optimized structures, charge distributions, bonding indicators and harmonic frequencies of various chemical mixtures hydrates and compared them to their elementary salts hydrates. We have further assessed the equilibrium products concentration of dehydration/hydrolysis of the chemical mixtures under a wide range of operating conditions. We observed that chemical mixing leads to an increase of the onset hydrolysis temperature with a maximum value of 79 K, thus increasing the resistance against hydrolysis with respect to the elementary salt hydrates. We also found that the chemical mixing of CaCl2 and MgCl2 hydrates widens the operating dehydration temperature range by a maximum value of 182 K (CaMg2Cl6·2H2O) and lowers the binding enthalpy with respect to the physical mixture by ≈65 kcal/mol for TCM based heat storage systems. PMID:28983386

Adsorption of acetanilide herbicides on soil and its components. II. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite.

PubMed

Liu, W P; Fang, Z; Liu, H J; Yang, W C

2001-04-01

Adsorption and catalytic hydrolysis of the herbicide diethatyl-ethyl [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester] on homoionic Na(+)-, K(+)-, Ca(2+)-, and Mg(2+)-montmorillonite clays were investigated in water solution. The Freundlich adsorption coefficient, Ki, got from isotherms on clay followed the order of Na+ approximately K+ > Mg2+ approximately Ca2+. Analysis of FT-IR spectra of diethatyl-ethyl adsorbed on clay suggests probable bonding at the carboxyl and amide carbonyl groups of the herbicide. The rate of herbicide hydrolysis in homoionic clay suspensions followed the same order as that for adsorption, indicating that adsorption may have preceded and thus caused hydrolysis. Preliminary product identification showed that hydrolysis occurred via nucleophilic substitution at the carboxyl carbon, causing the cleavage of the ester bond and formation of diethatyl and its dechlorinated derivative, and at the amide carbon, yielding an ethyl ester derivative and its acid. These pathways also suggest that hydrolysis of diethatyl-ethyl was catalyzed by adsorption on the clay surface.

Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: Water activity >0.6 below 200 K

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.

2016-05-01

Perchlorate salts found on Mars are extremely hygroscopic and form low eutectic temperature aqueous solutions, which could allow liquid water to exist on Mars despite cold and dry conditions. The formation, dynamics, and potential habitability of perchlorate salt solutions can be broadly understood in terms of water activity. Water activity controls condensation and evaporation of water vapor in brines, deliquescence and efflorescence of crystalline salts, and ice formation during freezing. Furthermore, water activity is a basic parameter defining the habitability of aqueous solutions. Despite the importance of water activity, its value in perchlorate solutions has only been measured at 298.15 K and at the freezing point of water. To address this lack of data, we have determined water activities in NaClO4, Ca(ClO4)2, and Mg(ClO4)2 solutions using experimental heat capacities measured by Differential Scanning Calorimetry. Our results include concentrations up to near-saturation and temperatures ranging from 298.15 to 178 K. We find that water activities in NaClO4 solutions increase with decreasing temperature, by as much as 0.25 aw from 298.15 to 178 K. Consequently, aw reaches ∼0.6-0.7 even for concentrations up to 15 molal NaClO4 below 200 K. In contrast, water activities in Ca(ClO4)2 and Mg(ClO4)2 solutions generally decrease with decreasing temperature. The temperature dependence of water activity indicates that low-temperature NaClO4 solutions will evaporate and deliquesce at higher relative humidity, crystallize ice at higher temperature, and potentially be more habitable for life (at least in terms of water activity) compared to solutions at 298.15 K. The opposite effects occur in Ca(ClO4)2 and Mg(ClO4)2 solutions.

Metallic elements (Ca, Hg, Fe, K, Mg, Mn, Na, Zn) in the fruiting bodies of Boletus badius.

PubMed

Kojta, Anna K; Falandysz, Jerzy

2016-06-01

The aim of this study was to investigate and compare the levels of eight metallic elements in the fruiting bodies of Bay Bolete (Boletus badius; current name Imleria badia) collected from ten sites in Poland to understand better the value of this popular mushroom as an organic food. Bay Bolete fruiting bodies were collected from the forest area near the towns and villages of Kętrzyn, Poniatowa, Bydgoszcz, Pelplin, Włocławek, Żuromin, Chełmno, Ełk and Wilków communities, as well as in the Augustów Primeval Forest. Elements such as Ca, Fe, K, Mg, Mn, Na and Zn were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-OES), and mercury by cold vapor atomic absorption spectrometry (CV-AAS). This made it possible to assess the nutritional value of the mushroom, as well as possible toxicological risks associated with its consumption. The results were subjected to statistical analysis (Kruskal-Wallis test, cluster analysis, principal component analysis). Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical measurements of Na-Ca-K exchange currents in intact outer segments isolated from bovine retinal rods

PubMed Central

1991-01-01

The properties of Na-Ca-K exchange current through the plasma membrane of intact rod outer segments (ROS) isolated from bovine retinas were studied with the optical probe neutral red. Small cellular organelles such as bovine ROS do not offer an adequate collecting area to measure Na-Ca-K exchange currents with electrophysiological techniques. This study demonstrates that Na-Ca-K exchange current in bovine ROS can be measured with the dye neutral red and dual-wavelength spectrophotometry. The binding of neutral red is sensitive to transport of cations across the plasma membrane of ROS by the effect of the translocated cations on the surface potential of the intracellular disk membranes (1985. J. Membr. Biol. 88: 249-262). Electrogenic Na+ fluxes through the ROS plasma membrane were measured with a resolution of 10(5) Na+ ions/ROS per s, equivalent to a current of approximately 0.01 pA; maximal electrogenic Na-Ca-K exchange flux in bovine ROS was equivalent to a maximal exchange current of 1-2 pA. Electrogenic Na+ fluxes were identified as Na-Ca-K exchange current based on a comparison between electrogenic Na+ flux and Na(+)-stimulated Ca2+ release with respect to flux rate, Na+ dependence, and ion selectivity. Neutral red monitored the net entry of a single positive charge carried by Na+ for each Ca2+ ion released (i.e., monitored the Na-Ca-K exchange current). Na-Ca-K exchange in the plasma membrane of bovine ROS had the following properties: (a) Inward Na-Ca-K exchange current required internal Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 0.9 microM), whereas outward Na-Ca-K exchange current required both external Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 1.1 microM) and external K+. (b) Inward Na-Ca-K exchange current depended in a sigmoidal manner on the external Na+ concentration, identical to Na(+)-stimulated Ca2+ release measured with Ca(2+)- indicating dyes. (c) The neutral red method was modified to measure Ca(2

Enhancement of the mechanoluminescence properties on Ca2MgSi2O7:Dy3+ phosphor by co-doping of charge compensator ions

NASA Astrophysics Data System (ADS)

Sahu, Ishwar Prasad

2016-08-01

In the present article, effect of charge compensator ions (R+ = Li+, Na+ and K+) on dysprosium-doped di-calcium magnesium di-silicate (Ca2MgSi2O7:Dy3+) phosphors were investigated. The Ca2MgSi2O7:Dy3+ and Ca2MgSi2O7:Dy3+, R+ phosphors, were prepared by solid-state reaction method. The crystal structures of sintered phosphors were an akermanite-type structure which belongs to the tetragonal crystallography. The peaks of mechanoluminescence (ML) intensity were increased linearly with increasing impact velocity of the moving piston. Thus, present investigation indicates that the piezoelectricity was responsible to produce ML in prepared phosphors. The time of the peak ML intensity and the decay rate did not change significantly with respect to increasing impact velocity. Addition of charge compensator ions enhances the luminescence intensity of prepared Ca2MgSi2O7:Dy3+ phosphors, because they neutralize the charge generated by Dy3+ substitution for Ca2+ ions. The role of Li+ ions among all charge compensator ions (Na+ or K+) used was found to be most effective for enhanced Dy3+ ion emission. These ML materials can be used in the devices such as stress sensor, fracture sensor, impact sensor, damage sensors, safety management monitoring system and fuse system for army warheads.

Effect of the cation size on the framework structures of magnesium tungstate, A4Mg(WO4)3 (A = Na, K), R2Mg2(WO4)3 (R = Rb, Cs).

PubMed

Han, Shujuan; Wang, Ying; Jing, Qun; Wu, Hongping; Pan, Shilie; Yang, Zhihua

2015-03-28

A series of alkali metal magnesium tungstates, A4Mg(WO4)3 (A = Na, K), R2Mg2(WO4)3 (R = Rb, Cs), were synthesized from a high temperature solution, and their structures were determined by single-crystal X-ray diffraction. Interestingly, Na4Mg(WO4)3 crystallizes in the monoclinic space group C2/c, while K4Mg(WO4)3 having an identical stoichiometry with Na4Mg(WO4)3, exhibits a different framework structure belonging to triclinic symmetry with the space group P1[combining macron]. Isostructural Rb2Mg2(WO4)3 and Cs2Mg2(WO4)3 crystallize in the space group P213 of cubic symmetry and reveal a three dimensional framework composed of isolated WO4 tetrahedra, MgO6 octahedra and RO12 (R = Rb, Cs) polyhedra. The effect of the alkali metal cation size on the framework structures of magnesium tungstate has been discussed in detail. In addition, the infrared spectra, as well as the UV-Vis-NIR diffuse reflectance spectroscopy data, are reported. The first-principles theoretical studies are also carried out to aid the understanding of electronic structures and linear optical properties.

The system Na2CO3-CaCO3 at 3 GPa

NASA Astrophysics Data System (ADS)

Podborodnikov, Ivan V.; Shatskiy, Anton; Arefiev, Anton V.; Rashchenko, Sergey V.; Chanyshev, Artem D.; Litasov, Konstantin D.

2018-04-01

It was suggested that alkali-alkaline earth carbonates may have a substantial role in petrological processes relevant to metasomatism and melting of the Earth's mantle. Because natrite, Na2CO3, Na-Ca carbonate (shortite and/or nyerereite), and calcite, CaCO3, have been recently reported from xenoliths of shallow mantle (110-115 km) origin, we performed experiments on phase relations in the system Na2CO3-CaCO3 at 3 GPa and 800-1300 °C. We found that the system has one intermediate compound, Na2Ca3(CO3)4, at 800 °C, and two intermediate compounds, Na2Ca(CO3)2 and Na2Ca3(CO3)4, at 850 °C. CaCO3 crystals recovered from experiments at 950 and 1000 °C are aragonite and calcite, respectively. Maximum solid solution of CaCO3 in Na2CO3 is 20 mol% at 850 °C. The Na-carbonate-Na2Ca(CO3)2 eutectic locates near 860 °C and 56 mol% Na2CO3. Na2Ca(CO3)2 melts incongruently near 880 °C to produce Na2Ca3(CO3)4 and a liquid containing about 51 mol% Na2CO3. Na2Ca3(CO3)4 disappears above 1000 °C via incongruent melting to calcite and a liquid containing about 43 mol% Na2CO3. At 1050 °C, the liquid, coexisting with Na-carbonate, contains 87 mol% Na2CO3. Na-carbonate remains solid up to 1150 °C and melts at 1200 °C. The Na2CO3 content in the liquid coexisting with calcite decreases to 15 mol% as temperature increases to 1300 °C. Considering the present and previous data, a range of the intermediate compounds on the liquidus of the Na2CO3-CaCO3 join changes as pressure increases in the following sequence: Na2Ca(CO3)2 (0.1 GPa) → Na2Ca(CO3)2, Na2Ca3(CO3)4 (3 GPa) → Na4Ca(CO3)3, Na2Ca3(CO3)4 (6 GPa). Thus, the Na2Ca(CO3)2 nyerereite stability field extends to the shallow mantle pressures. Consequently, findings of nyerereite among daughter phases in the melt inclusions in olivine from the sheared garnet peridotites are consistent with their mantle origin.

K-shell Photoionization of Na-like to Cl-like Ions of Mg, Si, S, Ar, and Ca

NASA Technical Reports Server (NTRS)

Witthoeft, M. C.; Garcia, J.; Kallman, T. R.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

2010-01-01

We present R-matrix calculations of photoabsorption and photoionization cross sections across the K edge of Mg, Si, S, Ar, and Ca ions with more than 10 electrons. The calculations include the effects of radiative and Auger damping by means of an optical potential. The wave functions are constructed from single-electron. orbital bases obtained using a Thomas-Fermi-Dirac statistical model potential. Configuration interaction is considered among all states up to n = 3. The damping processes affect the resonances converging to the K-thresholds causing them to display symmetric profiles of constant width that smear the otherwise sharp edge at the photoionization threshold. These data are important for the modeling of features found in photoionized plasmas.

On the entropy of glaucophane Na2Mg3Al2Si8O22(OH)2

USGS Publications Warehouse

Robie, R.A.; Hemingway, B.S.; Gillet, P.; Reynard, B.

1991-01-01

The heat capacity of glaucophane from the Sesia-Lanza region of Italy having the approximate composition (Na1.93Ca0.05Fe0.02) (Mg2.60Fe0.41) (Al1.83Fe0.15Cr0.01) (Si7.92Al0.08)O22(OH)2 was measured by adiabatic calorimetry between 4.6 and 359.4 K. After correcting the Cp0data to values for ideal glaucophane, Na2Mg3Al2Si8O22(OH)2 the third-law entropy S2980-S00was calculated to be 541.2??3.0 J??mol-1??K-1. Our value for S2980-S00is 12.0 J??mol-1??K-1 (2.2%) smaller than the value of Likhoydov et al. (1982), 553.2??3.0, is within 6.2 J??mol-1??K-1 of the value estimated by Holland (1988), and agrees remarkably well with the value calculated by Gillet et al. (1989) from spectroscopic data, 539 J??mol-1??K-1. ?? 1991 Springer-Verlag.

Increased oxidative stress and decreased activities of Ca2+/Mg2+-ATPase and Na+/K+-ATPase in the red blood cells of the hibernating black bear

USGS Publications Warehouse

Chauhan, V.P.S.; Tsiouris, J.A.; Chauhan, A.; Sheikh, A.M.; Brown, W. Ted; Vaughan, M.

2002-01-01

During hibernation, animals undergo metabolic changes that result in reduced utilization of glucose and oxygen. Fat is known to be the preferential source of energy for hibernating animals. Malonyldialdehyde (MDA) is an end product of fatty acid oxidation, and is generally used as an index of lipid peroxidation. We report here that peroxidation of lipids is increased in the plasma and in the membranes of red blood cells in black bears during hibernation. The plasma MDA content was about four fold higher during hibernation as compared to that during the active, non-hibernating state (P < 0.0001). Similarly, MDA content of erythrocyte membranes was significantly increased during hibernation (P < 0.025). The activity of Ca2+/Mg2+-ATPase in the erythrocyte membrane was significantly decreased in the hibernating state as compared to the active state. Na+/K+-ATPase activity was also decreased, though not significant, during hibernation. These results suggest that during hibernation, the bears are under increased oxidative stress, and have reduced activities of membrane-bound enzymes such as Ca2+/Mg2+-ATPase and Na+/K+-ATPase. These changes can be considered part of the adaptive for survival process of metabolic depression. ?? 2002 Elsevier Science Inc. All rights reserved.

K(Ca)3.1 channels facilitate K+ secretion or Na+ absorption depending on apical or basolateral P2Y receptor stimulation.

PubMed

Palmer, Melissa L; Peitzman, Elizabeth R; Maniak, Peter J; Sieck, Gary C; Prakash, Y S; O'Grady, Scott M

2011-07-15

Human mammary epithelial (HME) cells express several P2Y receptor subtypes located in both apical and basolateral membranes. Apical UTP or ATP-γ-S stimulation of monolayers mounted in Ussing chambers evoked a rapid, but transient decrease in short circuit current (I(sc)), consistent with activation of an apical K+ conductance. In contrast, basolateral P2Y receptor stimulation activated basolateral K+ channels and increased transepithelial Na+ absorption. Chelating intracellular Ca2+ using the membrane-permeable compound BAPTA-AM, abolished the effects of purinoceptor activation on I(sc). Apical pretreatment with charybdotoxin also blocked the I(sc) decrease by >90% and similar magnitudes of inhibition were observed with clotrimazole and TRAM-34. In contrast, iberiotoxin and apamin did not block the effects of apical P2Y receptor stimulation. Silencing the expression of K(Ca)3.1 produced ∼70% inhibition of mRNA expression and a similar reduction in the effects of apical purinoceptor agonists on I(sc). In addition, silencing P2Y2 receptors reduced the level of P2Y2 mRNA by 75% and blocked the effects of ATP-γ-S by 65%. These results suggest that P2Y2 receptors mediate the effects of purinoceptor agonists on K+ secretion by regulating the activity of K(Ca)3.1 channels expressed in the apical membrane of HME cells. The results also indicate that release of ATP or UTP across the apical or basolateral membrane elicits qualitatively different effects on ion transport that may ultimately determine the [Na+]/[K+] composition of fluid within the mammary ductal network.

Study of the quaternary Na+, K+//F-, Br-, NO 3 - reciprocal system using an innovative methodology

NASA Astrophysics Data System (ADS)

Morgunova, O. E.; Ukhanov, A. S.; Katasonova, E. A.; Trunin, A. S.; Surinskii, K. D.

2016-08-01

The topological structure of the quaternary Na+, K+//F-, Br-, NO 3 - system is studied using a computer-assisted research system. A tree of phases is constructed, and the eutectic characteristics of the secant triangle NaNO3-KBr-NaF, (equiv. %) 84.6 NaNO3-9.1 KBr-6.3 NaF, at 255.3°C are determined.

Calibration strategies for the direct determination of Ca, K, and Mg in commercial samples of powdered milk and solid dietary supplements using laser-induced breakdown spectroscopy (LIBS).

PubMed

Dos Santos Augusto, Amanda; Barsanelli, Paulo Lopes; Pereira, Fabiola Manhas Verbi; Pereira-Filho, Edenir Rodrigues

2017-04-01

This study describes the application of laser-induced breakdown spectroscopy (LIBS) for the direct determination of Ca, K and Mg in powdered milk and solid dietary supplements. The following two calibration strategies were applied: (i) use of the samples to calculate calibration models (milk) and (ii) use of sample mixtures (supplements) to obtain a calibration curve. In both cases, reference values obtained from inductively coupled plasma optical emission spectroscopy (ICP OES) after acid digestion were used. The emission line selection from LIBS spectra was accomplished by analysing the regression coefficients of partial least squares (PLS) regression models, and wavelengths of 534.947, 766.490 and 285.213nm were chosen for Ca, K and Mg, respectively. In the case of the determination of Ca in supplements, it was necessary to perform a dilution (10-fold) of the standards and samples to minimize matrix interference. The average accuracy for powdered milk ranged from 60% to 168% for Ca, 77% to 152% for K and 76% to 131% for Mg. In the case of dietary supplements, standard error of prediction (SEP) varied from 295 (Mg) to 3782mgkg -1 (Ca). The proposed method presented an analytical frequency of around 60 samples per hour and the step of sample manipulation was drastically reduced, with no generation of toxic chemical residues. Copyright © 2017 Elsevier Ltd. All rights reserved.

The antiepileptic effect of Centella asiatica on the activities of Na+/K+, Mg2+ and Ca2+-ATPases in rat brain during pentylenetetrazol–induced epilepsy

PubMed Central

G., Visweswari; K., Siva Prasad; V., Lokanatha; Rajendra, W.

2010-01-01

Background: To study the anticonvulsant effect of different extracts of Centella asiatica (CA) in male albino rats with reference to Na+/K+, Mg2+ and Ca2+-ATPase activities. Materials and Methods: Male Wistar rats (150±25 g b.w.) were divided into seven groups of six each i.e. (a) control rats treated with saline, (b) pentylenetetrazol (PTZ)-induced epileptic group (60 mg/kg, i.p.), (c) epileptic group pretreated with n-hexane extract (n-HE), (d) epileptic group pretreated with chloroform extract (CE), (e) epileptic group pretreated with ethyl acetate extract (EAE), (f) epileptic group pretreated with n-butanol extract (n-BE), and (g) epileptic group pretreated with aqueous extract (AE). Results: The activities of three ATPases were decreased in different regions of brain during PTZ-induced epilepsy and were increased in epileptic rats pretreated with different extracts of CA except AE. Conclusion: The extracts of C. asiatica, except AE, possess anticonvulsant and neuroprotective activity and thus can be used for effective management in treatment of epileptic seizures. PMID:20711371

Melting phase relations in the MgSiO3-CaSiO3 system at 24 GPa

NASA Astrophysics Data System (ADS)

Nomura, Ryuichi; Zhou, Youmo; Irifune, Tetsuo

2017-12-01

The Earth's lower mantle is composed of bridgmanite, ferropericlase, and CaSiO3-rich perovskite. The melting phase relations between each component are key to understanding the melting of the Earth's lower mantle and the crystallization of the deep magma ocean. In this study, melting phase relations in the MgSiO3-CaSiO3 system were investigated at 24 GPa using a multi-anvil apparatus. The eutectic composition is (Mg,Ca)SiO3 with 81-86 mol% MgSiO3. The solidus temperature is 2600-2620 K. The solubility of CaSiO3 component into bridgmanite increases with temperature, reaching a maximum of 3-6 mol% at the solidus, and then decreases with temperature. The same trend was observed for the solubility of MgSiO3 component into CaSiO3-rich perovskite, with a maximum of 14-16 mol% at the solidus. The asymmetric regular solutions between bridgmanite and CaSiO3-rich perovskite and between MgSiO3 and CaSiO3 liquid components well reproduce the melting phase relations constrained experimentally. [Figure not available: see fulltext.

Microstructures and Mechanical Study of Mg Alloy Foam Based on Mg-Zn-Ca-CaCO3 System

NASA Astrophysics Data System (ADS)

Erryani, A.; Pramuji, F.; Annur, D.; Amal, M. I.; Kartika, I.

2017-05-01

Magnesium alloy, a material that has potential to use some applications such as aerospace components, computer parts, and mobile phones. Magnesium alloy can also be a popular candidate as an orthopedic implant material for biodegradability, non-toxicity, and mechanical and physical properties that are excellent. Magnesium, one of the main macro elements required for the proper functioning of the human organism, is used to test the materials for biodegradable implants. The main objective of this study was to find out the microstructure, and mechanical characteristics of the Mg-Ca-Zn-CaCO3 alloy as porous implant materials are biodegradable. The presence of CaCO3 on the alloy functions as a foaming agent expected to produce gas bubbles during manufacturing process taken place that will form pores in the alloy. Mg-Ca-Zn-CaCO3 alloy was made by powder metallurgy method with three variations of composition (96Mg-Ca-3Zn-CaCO3, 91Mg-Ca-3Zn-5CaCO3, and 86Mg-Ca-3Zn-10CaCO3 wt%). Milling process was by using a shaker mill for 2 hours to produce a powder size distribution which was more homogeneous. The mixed powder was uniaxially pressed at a pressure of 100 MPa for 2 minutes and 200 MPa for 3 minutes into green compacts with dimensions of 10 mm in diameter and 10 mm in length. The sintering process was carried out at 650°C with a variation of holding time of 10 and 15 hours, and then the specimens were cooled down at room temperature. Microstructural analysis was performed by using X-Ray diffraction technique and Scanning electron microscopy equipped with an energy disperse spectrometry (EDS). The mechanical characteristics were analyzed by using Universal Testing Machine. The density and porosity of specimen were further measured by using Archimedes method. The results show that the optimum microstructure and mechanical characteristics are the holding time of 10 hours. The value of compression was 208.398 N/mm2, the density was 1.63 g/cc and a porosity was 18% on the

A Galinstan-Filled Capillary Probe for Thermal Conductivity Measurements and Its Application to Molten Eutectic {KNO}_3-{NaNO}_3-{NO}_2 (HTS) up to 700 K

NASA Astrophysics Data System (ADS)

Le Brun, Niccolò; Markides, Christos N.

2015-11-01

The successful measurement of the thermal conductivity of molten salts is a challenging undertaking due to the electrically conducting and possibly also aggressive nature of the materials, as well as the elevated temperatures at which these data are required. For accurate and reproducible measurements, it is important to develop a suitable experimental apparatus and methodology. In this study, we explore a modified version of the transient hot-wire method, which employs a molten-metal-filled capillary in order to circumvent some of the issues encountered in previous studies. Specifically, by using a novel flexible U-shaped quartz-capillary, filled with a eutectic mixture of gallium, indium and tin, commercially known as Galinstan, we proceed to measure the thermal conductivity of molten eutectic {KNO}_3-{NaNO}_3-{NaNO}_2. The new probe is demonstrated as being able to measure the thermal conductivity of this molten salt, which is found to range from 0.48 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} at 500 K to 0.47 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} at close to 700 K, with an overall expanded uncertainty (95 % confidence) of 3.1 %. The quartz is found to retain its electrically insulating properties and no current leakage is detected in the sample over the investigated temperature range. The thermal conductivity data reported in the present study are also used to elucidate a partial disagreement found in the literature for this material.

Interaction of peridotite with Ca-rich carbonatite melt at 3.1 and 6.5 GPa: Implication for merwinite formation in upper mantle, and for the metasomatic origin of sublithospheric diamonds with Ca-rich suite of inclusions

NASA Astrophysics Data System (ADS)

Sharygin, Igor S.; Shatskiy, Anton; Litasov, Konstantin D.; Golovin, Alexander V.; Ohtani, Eiji; Pokhilenko, Nikolay P.

2018-03-01

We performed an experimental study, designed to reproduce the formation of an unusual merwinite + olivine-bearing mantle assemblage recently described as a part of a Ca-rich suite of inclusions in sublithospheric diamonds, through the interaction of peridotite with an alkali-rich Ca-carbonatite melt, derived from deeply subducted oceanic crust. In the first set of experiments, we studied the reaction between powdered Mg-silicates, olivine and orthopyroxene, and a model Ca-carbonate melt (molar Na:K:Ca = 1:1:2), in a homogeneous mixture, at 3.1 and 6.5 GPa. In these equilibration experiments, we observed the formation of a merwinite + olivine-bearing assemblage at 3.1 GPa and 1200 °C and at 6.5 GPa and 1300-1400 °C. The melts coexisting with this assemblage have a low Si and high Ca content (Ca# = molar 100 × Ca/(Ca + Mg) > 0.57). In the second set of experiments, we investigated reaction rims produced by interaction of the same Ca-carbonate melt (molar Na:K:Ca = 1:1:2) with Mg-silicate, olivine and orthopyroxene, single crystals at 3.1 GPa and 1300 °C and at 6.5 GPa and 1400 °C. The interaction of the Ca-carbonate melt with olivine leads to merwinite formation through the expected reaction: 2Mg2SiO4 (olivine) + 6CaCO3 (liquid) = Ca3MgSi2O8 (merwinite) + 3CaMg(CO3)2 (liquid). Thus, our experiments confirm the idea that merwinite in the upper mantle may originate via interaction of peridotite with Ca-rich carbonatite melt, and that diamonds hosting merwinite may have a metasomatic origin. It is remarkable that the interaction of the Ca-carbonate melt with orthopyroxene crystals does not produce merwinite both at 3.1 and 6.5 GPa. This indicates that olivine grain boundaries are preferable for merwinite formation in the upper mantle.

Vasoconstriction triggered by hydrogen sulfide: Evidence for Na+,K+,2Cl-cotransport and L-type Ca2+ channel-mediated pathway.

PubMed

Orlov, Sergei N; Gusakova, Svetlana V; Smaglii, Liudmila V; Koltsova, Svetlana V; Sidorenko, Svetalana V

2017-12-01

This study examined the dose-dependent actions of hydrogen sulfide donor sodium hydrosulphide (NaHS) on isometric contractions and ion transport in rat aorta smooth muscle cells (SMC). Isometric contraction was measured in ring aortas segments from male Wistar rats. Activity of Na + /K + -pump and Na + ,K + ,2Cl - cotransport was measured in cultured endothelial and smooth muscle cells from the rat aorta as ouabain-sensitive and ouabain-resistant, bumetanide-sensitive components of the 86 Rb influx, respectively. NaHS exhibited the bimodal action on contractions triggered by modest depolarization ([K + ] o =30 mM). At 10 -4 M, NaHS augmented contractions of intact and endothelium-denuded strips by ~ 15% and 25%, respectively, whereas at concentration of 10 -3  M it decreased contractile responses by more than two-fold. Contractions evoked by 10 -4  M NaHS were completely abolished by bumetanide, a potent inhibitor of Na + ,K + ,2Cl - cotransport, whereas the inhibition seen at 10 -3  M NaHS was suppressed in the presence of K + channel blocker TEA. In cultured SMC, 5×10 -5  M NaHS increased Na + ,K + ,2Cl - - cotransport without any effect on the activity of this carrier in endothelial cells. In depolarized SMC, 45 Ca influx was enhanced in the presence of 10 -4  M NaHS and suppressed under elevation of [NaHS] up to 10 -3  M. 45 Ca influx triggered by 10 -4  M NaHS was abolished by bumetanide and L-type Ca 2+ channel blocker nicardipine. Our results strongly suggest that contractions of rat aortic rings triggered by low doses of NaHS are mediated by activation of Na + ,K + ,2Cl - cotransport and Ca 2+ influx via L-type channels.

Dependence of renal (Na+ + k+)-adenosine triphosphatase activity on thyroid status.

PubMed

Lo, S C; August, T R; Liberman, U A; Edelman, I S

1976-12-25

In thyroidectomized rats, a single injection of L-2,,5,2'-triiodothyronine (T3) (50mug/100 g body weight) elicited at 45% increase in (Na+ + k+)-dependent adenosine triphosphatase (NaK-ATPase) activity of the membrane-rich fraction of renal cortex at the optimal time of response, 48 h after injection. Three successive doses of T3 (50 mug/100 g body weight), given on alternate days, increased NaK-ATPase by 67% in the renal cortex but had no significant effect on the outer medulla or the papilla. Moreover, T3 had no effect on Mg2+-dependent adenosine trisphatase (MgATPase) in cortex, cedulla, or papilla. Three doses of T3 (50 mug/100 g body weight) given on alternate days to thyroidectomized rats elecited a 134, 79, and 46% increase in Vmax for ATP, Na4, and K+, respectively. There were no changes in the Km for ATP or the K1/2 values for Na+ and K+. Two methods were used to estimate the effect of T3 on the number of NaK-ATPase units (assumed to represent the number of Na+ pump sites); rat renal plasma membrane fractions were incubated with [gamma-32P]ATP, Mg2+, and Na+; the 32P-labeled membrane protein yeild was quantitatively dependent on Na+ and was hydrolyzed on addition of K+. There was a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of phosphorylated intermediate formed, in renal cortical membrane fractions from thyroidectomized rats given T3 or the diluent. There was also a linear correlation between the specific activity of NaK-ATPase (Vmax) and the amount of [3H]ouabain specifically bound (Na+-, Mg2+-, APT-dependent) to the NaK-ATPase preparation. Injection of T3 resulted in a 70% increase in NaK-ATPase activity, a 79% increase in formation of the phosphorylated intermediate, and a 65% increase in the [H]ouabain specifically bound to the NaK-ATPase system. The T3-dependent increases in Vmax for ATP, Na+, and K+ and the proportionate increases in the phosphorylated intermediate and in the amount of [3H]ouabain bound

K{sub 2}Mg{sub 5-x}Sn{sub 3} and K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, pb) with two types of Mg-Sn/Pb frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Xiao-Wu, E-mail: xwlei10@163.co

2011-04-15

K{sub 2}Mg{sub 5-x}Sn{sub 3} (x=0.28) and K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, Pb) have been synthesized by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction studies. K{sub 2}Mg{sub 5-x}Sn{sub 3} (x=0.28) is isostructural with Ni{sub 7-x}SbQ{sub 2} (Q=Se, Te) series and features 2D corrugated [Mg{sub 5-x}Sn{sub 3}] layers that are separated by K{sup +} cations. The structure of K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, Pb) is closely related to the Ho{sub 2}Rh{sub 12}As{sub 7} structural type and features 3D [Mg{sub 18}Tt{sub 11}] framework composed of 1D [Mg{sub 18}Tt{sub 11}] columns that aremore » interconnected via Mg-Tt bonds, forming 1D hexagonal tunnels occupied by the K+ cations. Electronic structure calculations indicate that Mg atoms can function as either electron donor or as a participator in the network along with Tt atoms. Magnetic property measurements and band structure calculations indicate that these compounds are metallic. -- Graphical abstract: Two new K-Mg-Tt phases, K{sub 2}Mg{sub 5-x}Sn{sub 3} (x=0.28) and K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, Pb), have been synthesized and structurally characterized. K{sub 2}Mg{sub 5-x}Sn{sub 3} is isostructural with Ni{sub 7-x}SbQ{sub 2} (Q=Se, Te) and features a 2D corrugated [Mg{sub 5}Sn{sub 3}] layer that is separated by K{sup +} cations, and K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, Pb) is closely related to the Ho{sub 2}Rh{sub 12}As{sub 7} structure type and features a 3D [Mg{sub 18}Tt{sub 11}] network with 1D hexagonal tunnels along the c-axis occupied by K{sup +} cations. Display Omitted Research highlights: Two new polar intermetallics, K{sub 2}Mg{sub 5-x}Sn{sub 3} (x=0.28) and K{sub 3}Mg{sub 18}Tt{sub 11} (Tt=Sn, Pb). Electronic structure calculations were performed by both TB-LMTO and EHTB methods. Mg atom can function as either electron donor or participator in the network.« less

The acute toxicity of major ion salts to Ceriodaphnia dubia: III. Mathematical models for mixture toxicity

EPA Science Inventory

Based on previous research on the acute toxicity of major ions (Na+, K+, Ca2+, Mg2+, Cl, SO42, and HCO3/CO32) to C. dubia, two mathematical models were developed for predicting the LC50 for any ion mixture, excluding those dominated by K toxicity. One model addresses a mechanism...

Inositol phosphates influence the membrane bound Ca/sup 2 +//Mg/sup 2 +/ stimulated ATPase from human erythrocyte membranes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kester, M.; Ekholm, J.; Kumar, R.

1986-03-01

The modulation by exogenous inositol phosphates of the membrane Ca/sup 2 +//Mg/sup 2 +/ ATPase from saponin/EGTA lysed human erythrocytes was determined in a buffer (pH 7.6) containing histidine, 80 mM, MgCl/sub 2/, 3.3 mM, NaCl, 74 mM, KCl, 30 mM, Na/sub 2/ATP, 2.3 mM, ouabain, 0.83 mM, with variable amounts of CaCl/sub 2/ and EGTA. The ATPase assay was linear with time at 44/sup 0/C. The inositol phosphates were commercially obtained and were also prepared from /sup 32/P labeled rabbit platelet inositol phospholipids. Inositol triphosphate (IP/sub 3/) elevated the Ca/sup 2 +//Mg/sup 2 +/ ATPase activity over basal levelsmore » in a dose, time, and calcium dependent manner and were increased up to 85% of control values. Activities for the Na/sup +//K/sup +/-ATPase and a Mg/sup 2 +/ ATPase were not effected by IP/sub 3/. Ca/sup 2 +//Mg/sup 2 +/APTase activity with IP/sub 2/ or IP/sub 3/ could be synergistically elevated with calmodulin addition. The activation of the ATPase with IP/sub 3/ was calcium dependent in a range from .001 to .02 mM. The apparent Km and Vmax values were determined for IP/sub 3/ stimulated Ca/sup 2 +//Mg/sup 2 +/ ATPase.« less

Efficient rare-earth free red-emitting Ca2YSbO6:Mn4+,M(M = Li+, Na+, K+, Mg2+) phosphors for white light-emitting diodes.

PubMed

Zhong, Jiasong; Chen, Daqin; Chen, Xiao; Wang, Keyuan; Li, Xinyue; Zhu, Yiwen; Ji, Zhenguo

2018-05-08

Owing to its low-cost and satisfactory luminescent-emission performance in warm white light-emitting diodes (w-LEDs), the non-rare-earth Mn4+-activated red phosphor has become a promising competitor of commercial rare-earth doped phosphor. In this study, a series of novel red-light emitting phosphors based on Ca2YSbO6:Mn4+ have been developed successfully by a conventional solid-state reaction. The structural and luminescent properties of these phosphors are systematically investigated. The as-prepared Ca2YSbO6:Mn4+ product exhibits a broad excitation band ranging from 250 to 600 nm and an abnormal intense deep-red emission centered at 680 nm with a full width at half maximum (FWHM) of ∼46 nm. The optimal Mn4+ doping concentration is about 0.3 mol%, and the concentration quenching mechanism is determined to be a dipole-dipole interaction. Impressively, the Ca2YSbO6:0.003Mn4+ phosphor shows an outstanding quantum efficiency of 62.6% and an excellent thermal stability. In addition, the effect of Li+, Mg2+, Na+ and K+ dopants on the luminescent properties of Mn4+-doped Ca2YSbO6 phosphors is elucidated. Furthermore, by employing the as-prepared Ca2YSbO6:Mn4+ as a red component, a warm w-LED with high color rendering index (Ra = 87.5) and low correlated color temperature (CCT = 3255 K) can be acquired. It is believed that the present phosphor has a potential application as a supplement of the red component for warm w-LEDs.

The Electrochemical Co-reduction of Mg-Al-Y Alloys in the LiCl-NaCl-MgCl2-AlF3-YCl3 Melts

NASA Astrophysics Data System (ADS)

Li, Mei; Liu, Yaochen; Han, Wei; Wang, Shanshan; Zhang, Milin; Yan, Yongde; Shi, Weiqun

2015-04-01

The electrochemical formation of Mg-Al-Y alloys was studied in the LiCl-NaCl-MgCl2 melts by the addition of AlF3 and YCl3 on a molybdenum electrode at 973 K (700 °C). In order to reduce the volatilization of salt solvent in the electrolysis process, the volatile loss of LiCl-NaCl-MgCl2 and LiCl-KCl-MgCl2 melts was first measured in the temperature range from 873 K to 1023 K (600 °C to 750 °C). Then, the electrochemical behaviors of Mg(II), Al(III), Y(III) ions and alloy formation processes were investigated by cyclic voltammetry, chronopotentiometry, and open circuit chronopotentiometry. The cyclic voltammograms indicate that the under-potential deposition of magnesium and yttrium on pre-deposited Al leads to formation of Mg-Al and Al-Y intermetallic compounds. The Mg-Al-Y alloys were prepared by galvanostatic electrolysis in the LiCl-NaCl-MgCl2-AlF3-YCl3 melts and characterized by X-ray diffraction and scanning electron microscopy with energy dispersive spectrometry. Composition of the alloys was analyzed by inductively coupled plasma-atomic emission spectrometer, and current efficiency was also determined by the alloy composition.

Structural, optoelectronic, and thermoelectric properties of AZn13 (A=Na, K, Ca, Sr, Ba) compounds

NASA Astrophysics Data System (ADS)

Basit, Abdul; Murtaza, G.; Mahmood, Asif; Yar, Abdullah; Muhammad, S.

2016-08-01

We report the structural, electronic, optical, and thermoelectric properties of the five cubic alkali-earth transition-metals AZn13 (A-Na, K, Ca, Sr, Ba) using density functional theory. Structural properties, electronic structures and optical behaviors are calculated explicitly via highly accurate contemporary full potential-linearized augmented plane wave (FP-LAPW) method. The investigated ground state data of these materials is quite close to the experimental information. The modified Becke-Johnson (mBJ) predicts the intermetallic nature of AZn13 (A-Na, K, Ca, Sr, Ba) materials. The complex dielectric function of these intermetallic compounds has been calculated and the observed noticeable peaks are examined through mBJ. With the help of complex dielectric function, the other important optical parameters like reflectivities, conductivities and refractive indices of AZn13 (A-Na, K, Ca, Sr, Ba) have been calculated as a function of energy. The optical response suggests that AZn13 (A-Na, K, Ca, Sr, Ba) compounds can be used for the optoelectronic devices. Further, the thermoelectric properties have been calculated through BoltzTraP program, the calculated values for different thermoelectric parameters recommend that these AZn13 (A-Na, K, Ca, Sr, Ba) materials are the suitable candidates for thermoelectric applications.

First-principles investigation for some physical properties of some fluoroperovskites compounds ABF3 (A = K, Na; B = Mg, Zn)

NASA Astrophysics Data System (ADS)

Bakri, Badis; Driss, Zied; Berri, Saadi; Khenata, Rabah

2017-12-01

In this work, the structural, electronic and optical properties of fluoroperovskite ABF3 (A = K, Na; B = Mg, Zn) were studied using two different approaches: the full-potential linearized augmented plane wave method and the pseudo-potential plane wave scheme in the frame of generalized gradient approximation features such as the lattice constant, bulk modulus and its pressure derivative are reported. The ground state properties of these compounds such as the equilibrium lattice constant and the bulk modulus are in good agreement with the experimental results. The first principles calculations were performed to study the electronic structures of ABF3(A = K, Na; B = Mg, Zn) compounds and the results indicated that these four compounds are indirect band gap insulators. The optical properties are analysed and the source of some peaks in the spectra is discussed. Besides, the dielectric function, refractive index and extinction coefficient for radiation up to 25 eV have also been reported and discussed.

Physiological responses to salt stress of salt-adapted and directly salt (NaCl and NaCl+Na2SO4 mixture)-stressed cyanobacterium Anabaena fertilissima.

PubMed

Swapnil, Prashant; Rai, Ashwani K

2018-05-01

Soil salinity in nature is generally mixed type; however, most of the studies on salt toxicity are performed with NaCl and little is known about sulfur type of salinity (Na 2 SO 4 ). Present study discerns the physiologic mechanisms responsible for salt tolerance in salt-adapted Anabaena fertilissima, and responses of directly stressed parent cells to NaCl and NaCl+Na 2 SO 4 mixture. NaCl at 500 mM was lethal to the cyanobacterium, whereas salt-adapted cells grew luxuriantly. Salinity impaired gross photosynthesis, electron transport activities, and respiration in parent cells, but not in the salt-adapted cells, except a marginal increase in PSI activity. Despite higher Na + concentration in the salt mixture, equimolar NaCl appeared more inhibitive to growth. Sucrose and trehalose content and antioxidant activities were maximal in 250 mM NaCl-treated cells, followed by salt mixture and was almost identical in salt-adapted (exposed to 500 mm NaCl) and control cells, except a marginal increase in ascorbate peroxidase activity and an additional fourth superoxide dismutase isoform. Catalase isoform of 63 kDa was induced only in salt-stressed cells. Salinity increased the uptake of intracellular Na + and Ca 2+ and leakage of K + in parent cells, while cation level in salt-adapted cells was comparable to control. Though there was differential increase in intracellular Ca 2+ under different salt treatments, ratio of Ca 2+ /Na + remained the same. It is inferred that stepwise increment in the salt concentration enabled the cyanobacterium to undergo priming effect and acquire robust and efficient defense system involving the least energy.

Ca-Al-rich chondrules and inclusions in ordinary chondrites

NASA Technical Reports Server (NTRS)

Bischoff, A.; Keil, K.

1983-01-01

Ca-Al-rich objects, hitherto mostly found in carbonaceous chondrites, are shown to be widespread, albeit rare, constituents of type 3 ordinary chondrites. Widespread occurrence and textural similarities of Ca-Al-rich chondrules to common, Mg-Fe-rich chondrules suggest that they formed by related processes. It is suggested in this article that Ca-Al-rich chondrules were formed by total melting and crystallization of heterogeneous, submillimeter- to submillimeter-sized dustballs made up of mixtures of high-temperature, Ca-Al-rich and lower-temperature, Na-K-rich components.

Effect of Mg/Ca ratios on microbially induced carbonate precipitation

NASA Astrophysics Data System (ADS)

Balci, Nurgul; Demirel, Cansu; Seref Sonmez, M.; Kurt, M. Ali

2016-04-01

Influence of Mg/Ca ratios on microbially induced carbonate mineralogy were investigated by series of experiments carried out under various environmental conditions (Mg/Ca ratio, temperature and salinity). Halophilic bacterial cultures used for biomineralization experiments were isolated from hypersaline Lake Acıgöl (Denizli, SW Turkey), displaying extreme water chemistry with an average pH around 8.6 (Balci eta l.,2015). Enriched bacterial culture used in the experiments consisted of Halomonas saccharevitans strain AJ275, Halomonas alimentaria strain L7B; Idiomarina sp. TBZ29, 98% Idiomarina seosensis strain CL-SP19. Biomineralization experiments were set up using above enriched culture with Mg/Ca ratios of 0.05, 1, 4 and 15 and salinity of 8% and 15% experiments at 30oC and 10oC. Additionally, long-term biomineralization experiments were set up to last for a year, for Mg/Ca=4 and Mg/Ca=15 experiments at 30oC. For each experimental condition abiotic experiments were also conducted. Solution chemistry throughout incubation was monitored for Na, K, Mg, Ca, bicarbonate, carbonate, ammonium and phosphate for a month. At the end of the experiments, precipitates were collected and morphology and mineralogy of the biominerals were investigated and results were evaluated using the software DIFFRAC.SUITE EVA. Overall the preliminary results showed chemical precipitation of calcite, halite, hydromagnesite and sylvite. Results obtained from biological experiments indicate that, low Mg/Ca ratios (0.05 and 1) favor chlorapatite precipitation, whereas higher Mg/Ca ratios favor struvite precipitation. Biomineralization of dolomite, huntite and magnesite is favorable at high Mg/Ca ratios (4 and 15), in the presence of halophilic bacteria. Moreover, results indicate that supersaturation with respect to Mg (Mg/Ca=15) combined with NaCl (15%) inhibits biomineralization and forms chemical precipitates. 15% salinity is shown to favor chemical precipitation of mineral phases more than

Mg- and K-bearing borates and associated evaporites at Eagle Borax spring, Death Valley, California: A spectroscopic exploration

USGS Publications Warehouse

Crowley, J.K.

1996-01-01

, although the high solubility of Mg borate minerals may prevent their formation in lacustrine settings and certainly inhibits their geologic preservation. The occurrence of Mg borates in borax-kernite deposits is also related to fractionation processes and points to the operation of an Mg borate chemical divide, characterized by Mg borate precipitation ahead of Mg carbonate. All of these considerations imply that Mg is a significant chemical component of many borate-depositing ground waters, even though Mg borate minerals may not be strongly evident in borate orebodies. The Eagle Borax spring borates and other evaporite minerals were studied using spectroscopic and X-ray powder diffraction methods, which were found to be highly complementary. Spectral reflectance measurements provide a sensitive means for detecting borates present in mixtures with other evaporites and can be used to screen samples rapidly for X-ray diffraction analysis. The apparently limited occurrence of Mg and K borate minerals compared to Ca and Na borates may stem partly from the inefficiency of X-ray diffraction methods for delineating the mineralogy of large and complex deposits. Spectral reflectance measurements can be made in the laboratory, in the field, on the mine face, and even remotely. Reflectance data should have an important role in studies of existing deposit mineralogy and related chemical fractionation processes, and perhaps in the discovery of new borate mineral resources.

Na+,K+-ATPase functionally interacts with the plasma membrane Na+,Ca2+ exchanger to prevent Ca2+ overload and neuronal apoptosis in excitotoxic stress.

PubMed

Sibarov, Dmitry A; Bolshakov, Artemiy E; Abushik, Polina A; Krivoi, Igor I; Antonov, Sergei M

2012-12-01

Using a fluorescent viability assay, immunocytochemistry, patch-clamp recordings, and Ca(2+) imaging analysis, we report that ouabain, a specific ligand of the Na(+),K(+)-ATPase cardiac glycoside binding site, can prevent glutamate receptor agonist-induced apoptosis in cultured rat cortical neurons. In our model of excitotoxicity, a 240-min exposure to 30 μM N-methyl-d-aspartate (NMDA) or kainate caused apoptosis in ∼50% of neurons. These effects were accompanied by a significant decrease in the number of neurons that were immunopositive for the antiapoptotic peptide Bcl-2. Apoptotic injury was completely prevented when the agonists were applied together with 0.1 or 1 nM ouabain, resulting in a greater survival of neurons, and the percentage of neurons expressing Bcl-2 remained similar to those obtained without agonist treatments. In addition, subnanomolar concentrations of ouabain prevented the increase of spontaneous excitatory postsynaptic current's frequency and the intracellular Ca(2+) overload induced by excitotoxic insults. Loading neurons with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or inhibition of the plasma membrane Na(+),Ca(2+)-exchanger by 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate (KB-R7943) eliminated ouabain's effects on NMDA- or kainite-evoked enhancement of spontaneous synaptic activity. Our data suggest that during excitotoxic insults ouabain accelerates Ca(2+) extrusion from neurons via the Na(+),Ca(2+) exchanger. Because intracellular Ca(2+) accumulation caused by the activation of glutamate receptors and boosted synaptic activity represents a key factor in triggering neuronal apoptosis, up-regulation of Ca(2+) extrusion abolishes its development. These antiapoptotic effects are independent of Na(+),K(+)-ATPase ion transport function and are initiated by concentrations of ouabain that are within the range of an endogenous analog, suggesting a novel functional role for Na(+),K(+)-ATPase in

An improved model for the calculation of CO2 solubility in aqueous solutions containing Na+, K+, Ca2+, Mg2+, Cl-, and SO42-

USGS Publications Warehouse

Duan, Zhenhao; Sun, R.; Zhu, Chen; Chou, I.-Ming

2006-01-01

An improved model is presented for the calculation of the solubility of carbon dioxide in aqueous solutions containing Na+, K+, Ca2+, Mg2+, Cl-, and SO42- in a wide temperature-pressure-ionic strength range (from 273 to 533 K, from 0 to 2000 bar, and from 0 to 4.5 molality of salts) with experimental accuracy. The improvements over the previous model [Duan, Z. and Sun, R., 2003. An improved model calculating CO2 solubility in pure water and aqueous NaCl solutions from 273 to 533K and from 0 to 2000 bar. Chemical Geology, 193: 257-271] include: (1) By developing a non-iterative equation to replace the original equation of state in the calculation of CO 2 fugacity coefficients, the new model is at least twenty times computationally faster and can be easily adapted to numerical reaction-flow simulator for such applications as CO2 sequestration and (2) By fitting to the new solubility data, the new model improved the accuracy below 288 K from 6% to about 3% of uncertainty but still retains the high accuracy of the original model above 288 K. We comprehensively evaluate all experimental CO2 solubility data. Compared with these data, this model not only reproduces all the reliable data used for the parameterization but also predicts the data that were not used in the parameterization. In order to facilitate the application to CO2 sequestration, we also predicted CO2 solubility in seawater at two-phase coexistence (vapor-liquid or liquid-liquid) and at three-phase coexistence (CO2 hydrate-liquid water-vapor CO2 [or liquid CO2]). The improved model is programmed and can be downloaded from the website http://www.geochem-model.org/programs.htm. ?? 2005 Elsevier B.V. All rights reserved.

Davinciite, Na12K3Ca6Fe{3/2+}Zr3(Si26O73OH)Cl2, a New K,Na-Ordered mineral of the eudialyte group from the Khibiny Alkaline Pluton, Kola Peninsula, Russia

NASA Astrophysics Data System (ADS)

Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.; Rozenberg, K. A.

2013-12-01

This paper presents a description of a new zirconosilicate of the eudialyte group, which was named davinciite in honor of Leonardo da Vinci (1452-1519), a famous Italian scientist, painter, sculptor and architect. The new mineral has been found in hyperagpaitic pegmatite at the Rasvumchorr Mountain, Khibiny Pluton, Kola Peninsula, as relict inclusions, up to 1-2 mm in size in a rastsvetaevite matrix. It is associated with nepheline, sodalite, potassium feldspar, delhayelite, aegirine, shcherbakovite, villiaumite, nitrite, nacaphite, rasvumite, and djerfisherite. Davinciite is dark lavender and transparent, with a vitreous luster and white streak. The new mineral is brittle, with conchoidal fracture; the Mohs' hardness is 5. No indications of cleavage or parting were observed. The measured density is 2.82(2) g/cm3 (volumetric method); the calculated density is 2.848 g/cm3. Davinciite is optically uniaxial, positive; ω = 1.603(2), ɛ = 1.605(2). It is nonpleochroic and nonfluorescent in UV light. The new mineral slowly breaks down and gelates in 50% HCl and HNO3. It is trigonal, space group R3m. The unit-cell dimensions are a = 14.2956(2), c = 30.0228(5) Å, V=5313.6(2) Å3. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are as follows: 2.981(100)(315), 2.860(96)(404), 4.309(66)(205), 3.207(63)(208), 6.415(54)(104), 3.162(43)(217). The chemical composition (electron microprobe, H2O calculated from X-ray diffraction data) is as follows, wt %: 12.69 Na2O, 3.53 K2O, 11.02 CaO, 0.98 SrO, 0.15 BaO, 5.33 FeO, 0.37 MnO, 0.07 Al2O3, 51.20 SiO2, 0.39 TiO2, 11.33 ZrO2, 0.21HfO2, 0.09 Nb2O5, 1.89 Cl, 0.93H2O, -O = Cl2 0.43; total is 99.75. The empirical formula calculated on the basis of Si + Al + Zr + Hf + Ti + Nb = 29 ( Z = 3) is (Na1l.75Sr0.29Ba0.03)Σ12.07(K2.28Na0.72)Σ3Ca5.99(Fe2.26Mn0.16)Σ2.42(Zr2.80Ti0.15Hf0.03Nb0.02) Σ3(Si1.96Al0.04)Σ2[Si3O9]2 [Si9O27]2[(OH)1.42O0.58]Σ2[Cl1.62(H2O)0.38]Σ2 · 0.48H2O. The simplified

Synthesis and crystal structures of nitratocobaltates Na2[Co(NO3)4], K2[Co(NO3)4], and Ag[Co(NO3)3] and potassium nitratonickelate K2[Ni(NO3)4

NASA Astrophysics Data System (ADS)

Morozov, I. V.; Fedorova, A. A.; Albov, D. V.; Kuznetsova, N. R.; Romanov, I. A.; Rybakov, V. B.; Troyanov, S. I.

2008-03-01

The cobalt(II) and nickel(II) nitrate complexes with an island structure (Na2[Co(NO3)4] ( I) and K2[Co(NO3)4] ( II)] and a chain structure [Ag[Co(NO3)3] ( III) and K2[Ni(NO3)4] ( IV)] are synthesized and investigated using X-ray diffraction. In the anionic complex [Co(NO3)4]2- of the crystal structure of compound I, the Co coordination polyhedron is a twisted tetragonal prism formed by the O atoms of four asymmetric bidentate nitrate groups. In the anion [Co(NO3)4]2- of the crystal structure of compound II, one of the four NO3 groups is monodentate and the other NO3 groups are bidentate (the coordination number of the cobalt atom is equal to seven, and the cobalt coordination polyhedron is a monocapped trigonal prism). The crystal structures of compounds III and IV contain infinite chains of the compositions [Co(NO3)2(NO3)2/2]- and [Ni(NO3)3(NO3)2/2]2-, respectively. In the crystal structure of compound III, seven oxygen atoms of one monodentate and three bidentate nitrate groups form a dodecahedron with an unoccupied vertex of the A type around the Co atom. In the crystal structure of compound IV, the octahedral polyhedron of the Ni atom is formed by five nitrate groups, one of which is terminal bidentate. The data on the structure of Co(II) coordination polyhedra in the known nitratocobaltates are generalized.

First investigations on the quaternary system Na2O-K2O-CaO-SiO2: synthesis and crystal structure of the mixed alkali calcium silicate K1.08Na0.92Ca6Si4O15

NASA Astrophysics Data System (ADS)

Kahlenberg, Volker; Mayerl, Michael Jean-Philippe; Schmidmair, Daniela; Krüger, Hannes; Tribus, Martina

2018-04-01

In the course of an exploratory study on the quaternary system Na2O-K2O-CaO-SiO2 single crystals of the first anhydrous sodium potassium calcium silicate have been obtained from slow cooling of a melt in the range between 1250 and 1050 °C. Electron probe micro analysis suggested the following idealized molar ratios of the oxides for the novel compound: K2O:Na2O:CaO:SiO2 = 1:1:12:8 (or KNaCa6Si4O15). Single-crystal diffraction measurements on a crystal with chemical composition K1.08Na0.92Ca6Si4O15 resulted in the following basic crystallographic data: monoclinic symmetry, space group P 21/ c, a = 8.9618(9) Å, b = 7.3594(6) Å, c = 11.2453(11) Å, β= 107.54(1)°, V = 707.2(1) Å3, Z = 2. Structure solution was performed using direct methods. The final least-squares refinement converged at a residual of R(|F|) = 0.0346 for 1288 independent reflections and 125 parameters. From a structural point of view, K1.08Na0.92Ca6Si4O15 belongs to the group of mixed-anion silicates containing [Si2O7]- and [SiO4]-units in the ratio 1:2. The mono- and divalent cations occupy a total of four crystallographically independent positions located in voids between the tetrahedra. Three of these sites are exclusively occupied by calcium. The fourth site is occupied by 54(1)% K and 46%(1) Na, respectively. Alternatively, the structure can be described as a heteropolyhedral framework based on corner-sharing silicate tetrahedra and [CaO6]-octahedra. The network can build up from kröhnkite-like [Ca(SiO4)2O2]-chains running along [001]. A detailed comparison with other A2B6Si4O15-compounds including topological and group-theoretical aspects is presented.

Ca removal and Mg recovery from flue gas desulfurization (FGD) wastewater by selective precipitation.

PubMed

Xia, Min; Ye, Chunsong; Pi, Kewu; Liu, Defu; Gerson, Andrea R

2017-11-01

Selective removal of Ca and recovery of Mg by precipitation from flue gas desulfurization (FGD) wastewater has been investigated. Thermodynamic analysis of four possible additives, Na 2 CO 3 , Na 2 C 2 O 4 , NaF and Na 2 SO 4 , indicated that both carbonate and oxalate could potentially provide effective separation of Ca via precipitation from Mg in FGD wastewater. However, it was found experimentally that the carbonate system was not as effective as oxalate in this regard. The oxalate system performed considerably better, with Ca removal efficiency of 96% being obtained, with little Mg inclusion at pH 6.0 when the dosage was ×1.4 the stoichiometric requirement. On this basis, the subsequent recovery process for Mg was carried out using NaOH with two-step precipitation. The product was confirmed to be Mg(OH) 2 (using X-ray diffraction and thermo gravimetric analysis) with elemental analysis suggesting a purity of 99.3 wt.%.

Mineral solubilities in the Na-K-Mg-Ca-Cl-SO 4-H 2O system: a re-evaluation of the sulfate chemistry in the Spencer-Møller-Weare model

NASA Astrophysics Data System (ADS)

Marion, Giles M.; Farren, Ronald E.

1999-05-01

The Spencer-Møller-Weare (SMW) (1990) model is parameterized for the Na-K-Mg-Ca-Cl-SO 4-H 2O system over the temperature range from -60° to 25°C. This model is one of the few complex chemical equilibrium models for aqueous solutions parameterized for subzero temperatures. The primary focus of the SMW model parameterization and validation deals with chloride systems. There are problems with the sulfate parameterization of the SMW model, most notably with sodium sulfate and magnesium sulfate. The primary objective of this article is to re-estimate the Pitzer-equation parameters governing interactions among sodium, potassium, magnesium, and calcium with sulfate in the SMW model. A mathematical algorithm is developed to estimate 22 temperature-dependent Pitzer-equation parameters. The sodium sulfate reparameterization reduces the overall standard error (SE) from 0.393 with the SMW Pitzer-equation parameters to 0.155. Similarly, the magnesium sulfate reparameterization reduces the SE from 0.335 to 0.124. In addition to the sulfate reparameterization, five additional sulfate minerals are included in the model, which allows a more complete treatment of sulfate chemistry in the Na-K-Mg-Ca-Cl-SO 4-H 2O system. Application of the model to seawater evaporation predicts gypsum precipitation at a seawater concentration factor (SCF) of 3.37 and halite precipitation at an SCF of 10.56, which are in good agreement with previous experimental and theoretical estimates. Application of the model to seawater freezing helps explain the two pathways for seawater freezing. Along the thermodynamically stable "Gitterman pathway," calcium precipitates as gypsum and the seawater eutectic is -36.2°C. Along the metastable "Ringer-Nelson-Thompson pathway," calcium precipitates as antarcticite and the seawater eutectic is -53.8°C.

NO levels in diabetes mellitus: Effects of l-NAME and insulin on LCAT, Na(+)/K(+) ATPase activity and lipid profile.

PubMed

Tekin, Neslihan; Akyüz, Fahrettin; Temel, Halide Edip

2011-01-01

Diabetes mellitus (DM) is a chronic disease and one of the most important health problems. Several factors may be responsible for the complications of diabetes mellitus including alterations in the activities of sodium-potassium adenosine triphosphatase (Na(+)/K(+) ATPase) and lecithin:cholesterol acyltransferase (LCAT) and also levels of nitric oxide (NO). We have investigated the effects of alterations in serum NO levels on activities of erythrocyte membran Na/K ATPase and serum LCAT enzymes. The experiments were performed on male rats divided into four groups: group 1, control (standart diet); group 2, diabetic control (single dose of 65mg/kg of streptozotocin (STZ), i.p); group 3, STZ+insulin (8IU/kg/day s.c.); group 4 (STZ+l-NAME 5mg/kg/day orally). Streptozotocin-induced diabetic rats, showed a significant increase in blood glucose and serum cholesterol (C) and triglyceride (TG). Compared to the control group with diabetic group plasma LCAT concentrations and erythrocyte membrane Na(+)/K(+) ATPase were found to be decreased. Activities of Na(+)/K(+) ATPase and serum NO level were decreased with the administration of l-NAME. We observed that insulin was ameliorated in all parameters. Serum NO levels is related to erythrocyte membrane Na(+)/K(+) ATPase activity. But serum NO levels did not affect the plasma LCAT activity and serum lipid profiles. Copyright © 2010 Diabetes India. Published by Elsevier Ltd. All rights reserved.

Hydrothermal synthesis and characterization of the first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortner, Teresa S.; Wurst, Klaus; Perfler, Lukas

2015-01-15

The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} was synthesized under hydrothermal conditions from Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}O and K{sub 2}B{sub 4}O{sub 7}·4H{sub 2}O using KNO{sub 3} as a nitrate source. The compound crystallizes in the space group Pnnm (no. 58) with the lattice parameters a=1320.8(3), b=910.7(2), and c=1232.5(3) pm (Z=4). Isolated Sechserrings formed by BO{sub 4} and BO{sub 3} groups are linked through hydrogen bridges to form a three-dimensional network. - Graphical abstract: The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} was synthesized under hydrothermal conditions from Na{sub 2}B{sub 4}O{sub 7}·10H{sub 2}Omore » and K{sub 2}B{sub 4}O{sub 7}·4H{sub 2}O using KNO{sub 3} as a nitrate source. - Highlights: • The first mixed alkali borate-nitrate K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3} is reported. • Hydrothermal conditions (240 °C, 3d) were used for the synthesis of K{sub 3}Na[B{sub 6}O{sub 9}(OH){sub 3}]NO{sub 3}. • Borate Sechserrings are interconnected through hydrogen-bonding.« less

Synthesis and structural characterization of the Zintl phases Na{sub 3}Ca{sub 3}TrPn{sub 4}, Na{sub 3}Sr{sub 3}TrPn{sub 4}, and Na{sub 3}Eu{sub 3}TrPn{sub 4} (Tr=Al, Ga, In; Pn=P, As, Sb)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yi; Suen, Nian-Tzu; College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002

15 new quaternary Zintl phases have been synthesized by solid-state reactions from the respective elements, and their structures have been determined by single-crystal X-ray diffraction. Na{sub 3}E{sub 3}TrPn{sub 4} (E=Ca, Sr, Eu; Tr=Al, Ga, In; Pn=P, As, Sb) crystallize in the hexagonal crystal system with the non-centrosymmetric space group P6{sub 3}mc (No. 186). The structure represents a variant of the K{sub 6}HgS{sub 4} structure type (Pearson index hP22) and features [TrPn{sub 4}]{sup 9–} tetrahedral units, surrounded by Na{sup +} and Ca{sup 2+}, Sr{sup 2+}, Eu{sup 2+} cations. The nominal formula rationalization [Na{sup +}]{sub 3}[E{sup 2+}]{sub 3}[TrPn{sub 4}]{sup 9–} follows themore » octet rule, suggesting closed-shell configurations for all atoms and intrinsic semiconducting behavior. However, structure refinements for several members hint at disorder and mixing of cations that potentially counteract the optimal valence electron count. - Graphical abstract: The hexagonal, non-centrosymmetric structure of Na{sub 3}E{sub 3}TrPn{sub 4} (E=Ca, Sr, Eu; Tr=Al, Ga, In; Pn=P, As, Sb) features [TrPn{sub 4}]{sup 9–} tetrahedral units, surrounded by Na{sup +} and Ca{sup 2+}, Sr{sup 2+}, Eu{sup 2+} cations. - Highlights: • 15 quaternary phosphides, arsenides, and antimonides are synthesized and structurally characterized. • The structure is a variant of the hexagonal K{sub 6}HgS{sub 4}-type, with distinctive pattern for the cations. • Occupational and/or positional disorder of yet unknown origin exists for some members of the series.« less

Theoretical study of 'Mixed' ligands superhalogens: Cl-M-NO3 (M = Li, Na, K)

NASA Astrophysics Data System (ADS)

Zhao, Xinghua; Liu, Weihui; Wang, Jiesheng; Li, Chun; Yuan, Guang

2016-08-01

MCl2-, M(NO3)2-, and (Cl-M-NO3)- (M = Li, Na, K) species are systematically investigated using the density functional theory. In all the cases studied, the vertical detachment energies (VDEs) exceed the electron affinity of chlorine atom, leading to the conclusion that MCl2-, M(NO3)2- and (Cl-M-NO3)- are superhalogens. The VDEs of (Cl-M-NO3)- are between that of MCl2- and M(NO3)2-, showing that replacing one ligand with a larger electronegative ligand leads to the higher VDE. Superhalogens with suitable VDEs can be built by using different ligands.

K+ and NH4(+) modulate gill (Na+, K+)-ATPase activity in the blue crab, Callinectes ornatus: fine tuning of ammonia excretion.

PubMed

Garçon, D P; Masui, D C; Mantelatto, F L M; McNamara, J C; Furriel, R P M; Leone, F A

2007-05-01

To better comprehend the mechanisms of ionic regulation, we investigate the modulation by Na+, K+, NH4(+) and ATP of the (Na+, K+)-ATPase in a microsomal fraction from Callinectes ornatus gills. ATP hydrolysis obeyed Michaelis-Menten kinetics with KM=0.61+/-0.03 mmol L(-1) and maximal rate of V=116.3+/-5.4 U mg(-1). Stimulation by Na+ (V=110.6+/-6.1 U mg(-1); K0.5=6.3+/-0.2 mmol L(-1)), Mg2+ (V=111.0+/-4.7 U mg(-1); K0.5=0.53+/-0.03 mmol L(-1)), NH4(+) (V=173.3+/-6.9 U mg(-1); K0.5=5.4+/-0.2 mmol L(-1)) and K+ (V=116.0+/-4.9 U mg(-1); K0.5=1.5+/-0.1 mmol L(-1)) followed a single saturation curve, although revealing site-site interactions. In the absence of NH4(+), ouabain (K(I)=74.5+/-1.2 micromol L(-1)) and orthovanadate inhibited ATPase activity by up to 87%; the inhibition patterns suggest the presence of F0F1 and K+-ATPases but not Na+-, V- or Ca2+-ATPase as contaminants. (Na+, K+)-ATPase activity was synergistically modulated by K+ and NH4(+). At 10 mmol L(-1) K+, increasing NH4(+) concentrations stimulated maximum activity to V=185.9+/-7.4 U mg(-1). However, at saturating NH4(+) (50 mmol L(-1)), increasing K+ concentrations did not stimulate activity further. Our findings provide evidence that the C. ornatus gill (Na+, K+)-ATPase may be particularly well suited for extremely efficient active NH4(+) excretion. At elevated NH4(+) concentrations, the enzyme is fully active, regardless of hemolymph K+ concentration, and K+ cannot displace NH4(+) from its exclusive binding sites. Further, the binding of NH4(+) to its specific sites induces an increase in enzyme apparent affinity for K+, which may contribute to maintaining K+ transport, assuring that exposure to elevated ammonia concentrations does not lead to a decrease in intracellular potassium levels. This is the first report of modulation by ammonium ions of C. ornatus gill (Na+, K+)-ATPase, and should further our understanding of NH4(+) excretion in benthic crabs.

Comparison between Mg II k and Ca II H images recorded by SUNRISE/SuFI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Danilovic, S.; Hirzberger, J.; Riethmüller, T. L.

2014-03-20

We present a comparison of high-resolution images of the solar surface taken in the Mg II k and Ca II H channels of the Filter Imager on the balloon-borne solar observatory SUNRISE. The Mg and Ca lines are sampled with 0.48 nm and 0.11 nm wide filters, respectively. The two channels show remarkable qualitative and quantitative similarities in the quiet Sun, in an active region plage and during a small flare. However, the Mg filtergrams display 1.4-1.7 times higher intensity contrast and appear more smeared and smoothed in the quiet Sun. In addition, the fibrils in a plage are wider.more » Although the exposure time is 100 times longer for Mg images, the evidence suggests that these differences cannot be explained only with instrumental effects or the evolution of the solar scene. The differences at least partially arise because of different line-formation heights, the stronger response of Mg k emission peaks to the higher temperatures, and the larger height range sampled by the broad Mg filter used here. This is evidently manifested during the flare when a surge in Mg evolves differently than in Ca.« less

Thermo and mechanoluminescence of Dy3+ activated K2Mg2(SO4)3 phosphor

NASA Astrophysics Data System (ADS)

Panigrahi, A. K.; Dhoble, S. J.; Kher, R. S.; Moharil, S. V.

2003-08-01

A solid state diffusion method for the preparation of (K2 : Dy)Mg2(SO4)3 and (K2 : Dy,P)Mg2(SO4)3 phosphors is reported. Thermoluminescence (TL) and mechanoluminescence (ML) characteristics are studied. TL, shown by the (K2 : Dy,P)Mg2(SO4)3 phosphor is 60% as intense as the conventional CaSO4 : Dy phosphor used in the TLD of ionization radiation. It has a linear TL dose response and a negligible fading. These properties of (K2 : Dy,P)Mg2(SO4)3 should be suitable in dosimetry of ionization radiation using TL technique. ML of (K2 : Dy)Mg2(SO4)3 shows one peak which has been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radicals (anion radicals produced by γ-irradiation) released from traps during the mechanical pressure applied on the Dy activated K2Mg2(SO4)3 phosphor. This ML mechanism is proposed for γ-irradiated sulfate based phosphors. It has been found that the total light output, i.e. ML intensity, increases with concentration of dopant, strain rate and irradiation dose of the phosphor. Mechanoluminescence and ML emission spectra of (K2 : Dy)Mg2(SO4)3 were recorded for better understanding of the ML process. The TL and ML measurements have also been performed to elucidate the mechanism of ML. Some correlation between ML and TL has also been found.

Phase transition behavior of (K,Na)NbO3-based high-performance lead-free piezoelectric ceramic composite with different phase compositions depending on Na fraction

NASA Astrophysics Data System (ADS)

Yamada, Hideto; Matsuoka, Takayuki; Yamazaki, Masato; Ohbayashi, Kazushige; Ida, Takashi

2018-01-01

The structures of the main (K1- x Na x )NbO3 perovskite in a high-performance lead-free piezoelectric ceramic composite (K1- x Na x )0.86Ca0.04Li0.02Nb0.85O3-δ-K0.85Ti0.85Nb1.15O5-BaZrO3-MgO-Fe2O3 (x = 0.52 and 0.70) with trace amounts of LiMgFeTiO4 inverse spinel and (Li,K)2(Mg,Fe,Ti,Nb)6O13 layered structure have been investigated by transmission electron microscopy (TEM) and synchrotron powder X-ray diffractometry (XRD) with varying temperatures. The bright-field TEM images have shown tetragonal 90°-domain contrasts at 80 and 40 °C, and the XRD profile has been simulated by adding an average structure of two differently oriented tetragonal structures bound by a 90°-domain wall for the x = 0.52 sample. Aggregates of tilted NbO6 nanodomains have been observed in a high-resolution TEM image, and the crossover of P4mm-Amm2 features from 60 to 20 °C and diffuse 2 × 2 × 2 superlattice reflections of the tilted NbO6 Imm2 structure have been observed in XRD data for the x = 0.70 sample.

Partitioning of Mg, Ca, and Na between carbonatite melt and hydrous fluid at 0.1-0.2 GPa

NASA Astrophysics Data System (ADS)

Veksler, Ilya V.; Keppler, Hans

Experimental studies of the element distribution between carbonatite melts and hydrous fluids are hampered by the fact that neither the fluid nor the melt can be isochemically quenched in conventional high-pressure vessels. In order to overcome this problem, we used a double-capsule technique to separate immiscible fluid and melt phases during and after the runs. The inner platinum capsules were charged with carbonate mixtures (CaCO3, MgCO3 and Na2CO3) and placed inside the outer capsules charged with distilled water and diamond powder. The latter was used as an inert trap for solids precipitating from the fluid on quenching. Carbonate melt and hydrous fluid equilibrated through a small hole left in the upper end of the inner capsule. The runs were performed in rapid-quench cold-seal pressure vessels at 0.1-0.2 GPa and 700-900°C in the two-phase (fluid+melt) stability region. Both quenched melt and quenched fluid were dissolved in dilute HCl and analysed by inductively coupled plasma atomic emission spectroscopy. The results show that under all conditions investigated, fluid/melt partition coefficients for Ca and Mg are similar and several times smaller than those for Na. At 0.1 GPa and a water/carbonatite ratio of 1 (by weight), the partition coefficients are DNa= 0.35+/- 0.02, DCa=0.09+/-0.02, and DMg=0.13+/- 0.01. Between 700 and 900°C, the effect of temperature on partitioning is negligible. However, DNa increases significantly with decreasing water/carbonatite ratio in the system. Our data show that the release of a hydrous fluid enriched in sodium and simultaneous crystallisation of calcite can transform an alkaline, vapour-saturated carbonatite melt into a body of pure calcite surrounded by zones of sodium metasomatism. Thus, it is quite possible that carbonate magmas with substantial amounts of alkalies were common parental liquids of plutonic carbonatites.

Kinetics of Reduction of CaO-FeO x -MgO-PbO-SiO2 Slags by CO-CO2 Gas Mixtures

NASA Astrophysics Data System (ADS)

Jahanshahi, Sharif; Wright, Steven

2017-08-01

Kinetics of the reaction of lead slags (PbO-CaO-SiO2-FeO x -MgO) with CO-CO2 gas mixtures was studied by monitoring the changes in the slag composition when a stream of CO-CO2 gas mixture was blown on the surface of thin layers of slags (3 to 10 mm) at temperatures in the range of 1453 K to 1593 K (1180 °C to 1320 °C). These measurements were carried out under conditions where mass transfer in the gas phase was not the rate-limiting step and the reduction rates were insensitive to factors affecting mass transfer in the slag phase. The results show simultaneous reduction of PbO and Fe2O3 in the slag. The measured specific rate of oxygen removal from the melts varied from about 1 × 10-6 to 4 × 10-5 mol O cm-2 s-1 and was strongly dependent on the slag chemistry and its oxidation state, partial pressure of CO in the reaction gas mixture, and temperature. The deduced apparent first-order rate constant increased with increasing iron oxide content, oxidation state of the slag, and temperature. The results indicate that under the employed experimental conditions, the rate of formation of CO2 at the gas-slag interface is likely to be the rate-limiting step.

Effect of K+ and Na+ on calcium-dependent electron-dense particles in the monoaminergic synaptic vesicles of rat pineal nerves fixed in Ca2+-containing solutions.

PubMed

Pellegrino de Iraldi, A; Corazza, J P

1983-01-01

The effect of K+ and Na+ on the Ca2+ binding site in the dense core of monoaminergic vesicles of pineal nerves was investigated in the rat. Rat pineal glands, bisected immediately after decapitation, were incubated at room temperature in solutions containing high K+ or high Na+ in the presence or absence of Ca2+. Fixation was performed in glutaraldehyde-osmium tetroxide in collidine buffer, with and without CaCl2. It was confirmed that, after fixation in Ca2+-containing solutions, an electron-dense particle, located in the vesicle core, which can be considered a calcium deposit, appears within the synaptic vesicles. It was observed that this Ca2+ deposit may be modified by incubation in a high K+ or high Na+ milieu before fixation in Ca2+ containing solutions. When the incubation was carried out with high K+ and high Ca2+ simultaneously, Ca2+ deposits were considerably increased. With K+ alone, no Ca2+ deposits were apparent, as when electrical stimulation is applied before fixation. This effect was not observed when the incubation was done in high Na+. Consecutive incubations in high K+ and high Na+, respectively, restored the capability of the vesicle cores to bind Ca2+. Prolonged incubation in high Na+ before fixation increased Ca2+ deposits within the vesicles. These findings are in line with data on the effect of these ions upon the storage and release of biogenic amines and suggest that these ions modify the capability of synaptic vesicles to bind Ca2+.

A Comparative Study of the Corrosion Behavior of Three Stainless Steels in an Eutectic (Li,Na,K)2CO3 Melt with and without (Na,K)Cl Additives at 973K in Air

NASA Astrophysics Data System (ADS)

Zeng, C. L.; Liu, Y.

2011-04-01

The ternary carbonate eutectic mixture of Li2CO3, K2CO3 and Na2CO3 as a heat transfer and storage medium has excellent thermophysical properties, but with high viscidity as compared with some other inorganic salts such as chlorides and nitrates. The addition of chlorides or fluorides to molten carbonates may improve their fluidity, but possibly making the melt become more corrosive. In this study, the corrosion behavior of type 304, 310 and 316 stainless steels in an eutectic (Li,Na,K)2CO3 melt with and without an eutectic mixture of NaCl and KCl at 973K in air have been examined. The experimental results indicated that 310 steel shows a much better corrosion resistance in molten carbonates than both 304 and 316 steels, due to the formation of a continuous LiCrO2 scale. The addition of chlorides to carbonates melt accelerated the corrosion of the steels, especially 310 steel, producing scales with more porosity.

Structural and electrical properties of 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Tae-Ho; Lee, Sung-Gap, E-mail: lsgap@gnu.ac.kr; Yeo, Jin-Ho

2014-10-15

Highlights: • We fabricated lead-free (Na{sub 0.5}K{sub 0.5})NbO{sub 3} ceramics. • We studied the structural and electrical properties of 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics. • The structural and electrical properties improved with increasing amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3}. - Abstract: In this study, 1 − x(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–x(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} ceramics were fabricated using the conventional mixed oxide method. The effects of the addition of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} on the structural and electrical properties of the specimens were investigated for their application in piezoelectric devices. As the results of X-ray diffractionmore » analysis show, all specimens display the typical polycrystalline perovskite structure without the presence of the second phase. Sintered densities increased with an increase in the amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} added and the specimen with 0.08 mol% of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} added showed the maximum value of 4.54 g/cm{sup 3}. Both average grain size and densification increased with an increase in the amount of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3}. The electromechanical coupling factor, dielectric constant ϵ{sub r}, dielectric loss tan δ, d{sub 33} and Curie temperature of the 0.92(Na{sub 0.5}K{sub 0.5})NbO{sub 3}–0.08(Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} specimens doped with 0.08 mol% of (Sr{sub 0.5}Ca{sub 0.5})TiO{sub 3} were 0.31, 1338, 0.021, 138 and 445 °C, respectively.« less

Recombination luminescence of CaSO4:Tb3+ and CaSO4:Gd3+phosphors

NASA Astrophysics Data System (ADS)

Kudryavtseva, Irina; Lushchik, Aleksandr; Maaroos, Aarne; Azmaganbetova, Zhannur; Nurakhmetov, Turlybek; Salikhoja, Zhussupbek

2012-08-01

A comparative study of the excitation of luminescence by VUV radiation as well as of thermally and photostimulated luminescence has been carried out for CaSO4:Tb3+ and CaSO4:Gd3+ phosphors, where Na+ or F- ions are used for charge compensation. The distinction in hole processes for the phosphors with Na+ or F- compensators is determined by the differing thermal stability of the holes localized at/near Tb3+Na+ and Gd3+Na+ (up to 100-160 K) or at/near Tb3+F- V Ca and Gd3+F- V Ca centers involving also a cation vacancy (up to 400-550 K). Tunnel luminescence in the pairs of localized electrons and holes nearby Tb3+ or Gd3+ has been detected. The mechanisms of electron-hole, hole-electron and tunnel recombination luminescence as well as a subsequent released energy transfer to RE3+ ions are considered.

The stability of Cl-CO3-scapolite relative to plagioclase + CaCO3 + CaSO4 in the presence of NaCl brines as a function of P-T-XNaCl

NASA Astrophysics Data System (ADS)

Harlov, D. E.; Budzyn, B.

2008-12-01

Cl-CO3-scapolite [(Na,Ca)4[Al3 (Al,Si) 3 Si3 O24](Cl, CO3 , SO4 )] occurs as a common partial to total alteration of plagioclase in deep-crustal xenoliths, skarns, marbles, gabbros, metabasites, calc-silicate gneisses, as well as in quartzofeldspathic granulite-facies rocks in general (Moecher and Essene, 1990, J Petrol 31, 997). Alteration of plagioclase to Cl-CO3-scapolite is presumed due to metasomatism by CO2-NaCl-H2O fluids (Satish-Kumar and Santosh, 1998, Geol Mag 135, 27). Previous experimental work on CO3-scapolite has focused on reversing the equilibrium 3 CaAl2 Si2 O8 + CaCO3 = Ca4 Al6 Si6 O24 CO3 in either pure CO2 (Goldschmidt and Newton, 1977, Am Mineral 62, 1063) or in CO2-H2O (Huckenholz and Seiberl, 1989 Abs IGC 28, 2.79). These experiments have determined that the anorthite- calcite-scapolite equilibrium is nearly pressure-invariant in P-T space (200 to 1500 MPa) occurring at approximately 790 to 820 °C (Huckenholz and Seiberl, 1989). In this study, a series of experiments, involving the equilibrium 3 Plagioclase(An60) + 0.5 CaCO3 + 0.5 CaSO4 = [(Na,Ca)4[Al3 (Al,Si)3 Si3 O24](Cl, CO3, SO4 )] plus an NaCl brine (10/90, 20/80, 30/70, and 50/50 molar NaCl/H2O) have been done at 500, 1000, and 1500 MPa and 600 to 900 °C. Natural plagioclase and scapolite, along with synthetic calcite and anhydrite, were lightly ground together in equi-molar amounts in ethanol. The mineral mix (10 mg) + NaCl brine (5 mg), or pure H2O (1.5 mg), were loaded into 3 mm diameter/1.3 mm long Pt capsules which were arc-welded shut, folded, and placed horizontally in a CaF2 setup (with graphite oven), such that the thermocouple tip touched the Pt capsule, or placed in a hydrothermal autoclave (600 and 700 °C; 500 MPa) with an internal thermocouple. A series of duplicate experiments for the same mineral mix, at the same P-T conditions, were done utilizing pure H2O as the flux. The H2O-only experiments duplicated the P-T reversals of Huckenholz and Seiberl (1989). In contrast

Effects of Fe-Enrichment on the Equation of State and Stability of (Mg,Fe)SiO3 Perovskite and Post-Perovskite

NASA Astrophysics Data System (ADS)

Dorfman, S. M.; Holl, C. M.; Meng, Y.; Prakapenka, V.; Duffy, T. S.

2010-12-01

Fe-enrichment in the deep lower mantle has been proposed as an explanation for seismic anomalies such as large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs). In order to resolve the effect of Fe on the stability and equation of state of the lower mantle’s dominant constituent, (Mg,Fe)SiO3 perovskite, we have studied Fe-rich natural orthopyroxenes, (Mg0.61Fe0.37Ca0.02)SiO3 and (Mg0.25Fe0.70Ca0.05)SiO3 (compositions determined by microprobe analysis), at lower mantle P-T conditions. Pyroxene starting materials were mixed with Au (pressure calibrant and laser absorber) and loaded with NaCl or Ne (pressure medium and thermal insulator) in a symmetric diamond anvil cell. X-ray diffraction experiments at pressures up to 122 GPa with in-situ laser heating were performed at the GSECARS (13-ID-D) and HPCAT (16-ID-B) sectors of the Advanced Photon Source. Heating samples to 2000 K produced single-phase orthorhombic GdFeO3-type perovskite at 63 GPa for the Mg# 61 composition and at 72 GPa for the Mg# 25 composition. At lower pressures (56 GPa for Mg# 61, 67 GPa for Mg# 25), heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression to 93 GPa and higher pressures with laser heating, Mg# 25 perovskite transformed to a two-phase mixture of perovskite and post-perovskite. This is consistent with previous findings that Fe substitution destabilizes (Mg,Fe)SiO3 perovskite relative to (Mg,Fe)SiO3 post-perovskite (Mao et al. 2004, Caracas and Cohen 2005). The bulk modulus at 80 GPa (K80) is ~550 GPa for both Fe-rich perovskites, comparable to values measured for MgSiO3 perovskite (Lundin et al. 2008). However, the volume of Fe-rich perovskites increases linearly with Fe-content. The (Mg0.25Fe0.70Ca0.05)SiO3 perovskite is 3% greater at 80 GPa than V80 for the Mg end

Heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(s)

NASA Technical Reports Server (NTRS)

Leu, Ming-Taun; Timonen, Raimo S.; Keyser, Leon F.; Yung, Yuk L.

1995-01-01

The heterogeneous reactions of HNO3(g) + NaCl(s) yields HCl(g) + NaNO3(s) (eq 1) and N2O5(g) + NaCl(s) yields ClNO2(g) + NaNO3(S) (eq 2) were investigated over the temperature range 223-296 K in a flow-tube reactor coupled to a quadrupole mass spectrometer. Either a chemical ionization mass spectrometer (CIMS) or an electron-impact ionization mass spectrometer (EIMS) was used to provide suitable detection sensitivity and selectivity. In order to mimic atmospheric conditions, partial pressures of HNO3 and N2O5 in the range 6 x 10(exp -8) - 2 x 10(exp -6) Torr were used. Granule sizes and surface roughness of the solid NaCl substrates were determined by using a scanning electron microscope. For dry NaCl substrates, decay rates of HNO3 were used to obtain gamma(1) = 0.013 +/- 0.004 (1sigma) at 296 K and > 0.008 at 223 K, respectively. The error quoted is the statistical error. After all corrections were made, the overall error, including systematic error, was estimated to be about a factor of 2. HCl was found to be the sole gas-phase product of reaction 1. The mechanism changed from heterogeneous reaction to predominantly physical adsorption when the reactor was cooled from 296 to 223 K. For reaction 2 using dry salts, gamma(2) was found to be less than 1.0 x 10(exp -4) at both 223 and 296 K. The gas-phase reaction product was identified as ClNO2 in previous studies using an infrared spectrometer. An enhancement in reaction probability was observed if water was not completely removed from salt surfaces, probably due to the reaction of N2O5(g) + H2O(s) yields 2HNO3(g). Our results are compared with previous literature values obtained using different experimental techniques and conditions. The implications of the present results for the enhancement of the hydrogen chloride column density in the lower stratosphere after the El Chichon volcanic eruption and for the chemistry of HCl and HNO3 in the marine troposphere are discussed.

Calcium-activated K(+) channel (K(Ca)3.1) activity during Ca(2+) store depletion and store-operated Ca(2+) entry in human macrophages.

PubMed

Gao, Ya-dong; Hanley, Peter J; Rinné, Susanne; Zuzarte, Marylou; Daut, Jurgen

2010-07-01

STIM1 'senses' decreases in endoplasmic reticular (ER) luminal Ca(2+) and induces store-operated Ca(2+) (SOC) entry through plasma membrane Orai channels. The Ca(2+)/calmodulin-activated K(+) channel K(Ca)3.1 (previously known as SK4) has been implicated as an 'amplifier' of the Ca(2+)-release activated Ca(2+) (CRAC) current, especially in T lymphocytes. We have previously shown that human macrophages express K(Ca)3.1, and here we used the whole-cell patch-clamp technique to investigate the activity of these channels during Ca(2+) store depletion and store-operated Ca(2+) influx. Using RT-PCR, we found that macrophages express the elementary CRAC channel components Orai1 and STIM1, as well as Orai2, Orai3 and STIM2, but not the putatively STIM1-activated channels TRPC1, TRPC3-7 or TRPV6. In whole-cell configuration, a robust Ca(2+)-induced outwardly rectifying K(+) current inhibited by clotrimazole and augmented by DC-EBIO could be detected, consistent with K(Ca)3.1 channel current (also known as intermediate-conductance IK1). Introduction of extracellular Ca(2+) following Ca(2+) store depletion via P2Y(2) receptors induced a robust charybdotoxin (CTX)- and 2-APB-sensitive outward K(+) current and hyperpolarization. We also found that SOC entry induced by thapsigargin treatment induced CTX-sensitive K(+) current in HEK293 cells transiently expressing K(Ca)3.1. Our data suggest that SOC and K(Ca)3.1 channels are tightly coupled, such that a small Ca(2+) influx current induces a much large K(Ca)3.1 channel current and hyperpolarization, providing the necessary electrochemical driving force for prolonged Ca(2+) signaling and store repletion. Copyright 2010 Elsevier Ltd. All rights reserved.

Surface characterization, in vitro and in vivo biocompatibility of Mg-0.3Sr-0.3Ca for temporary cardiovascular implant.

PubMed

Bornapour, M; Mahjoubi, H; Vali, H; Shum-Tim, D; Cerruti, M; Pekguleryuz, M

2016-10-01

Magnesium-based alloys are attractive candidate materials for medical applications. Our earlier work showed that the ternary Mg-0.3Sr-0.3Ca alloy exhibits slower degradation rates than both binary Mg-Sr and Mg-Ca alloys. The ternary alloy immersed in simulated body fluid (SBF) forms a compact surface layer of corrosion products that we hypothesized to be a Sr-substituted hydroxyapatite (HA). The main objectives of the current work are to understand the bio-degradation mechanism of Mg-0.3Sr-0.3Ca, to identify the exact nature of its protective layer and to evaluate the in vitro and in vivo biocompatibility of the alloy for cardiovascular applications. To better simulate the physiological environment, the alloy was immersed in SBF which was daily refreshed. Raman spectroscopy and X-Ray photoelectron spectroscopy (XPS) confirmed the formation of a thin, Sr-substituted HA layer at the interface between the alloy and the corrosion products. In vitro biocompatibility evaluated via indirect cytotoxicity assays using HUVECs showed no toxicity effect and ions extracted from Mg-0.3Sr-0.3Ca in fact increased the viability of HUVECs after one week. In vivo tests were performed by implanting a tubular Mg-0.3Sr-0.3Ca stent along with a WE43 control stent into the right and left femoral artery of a dog. Post implantation and histological analyses showed no thrombosis in the artery with Mg-0.3Sr-0.3Ca stent after 5weeks of implantation while the artery implanted with WE43 stent was extensively occluded and thrombosed. Microscopic observation of the Mg-0.3Sr-0.3Ca implant-tissue interface confirmed the in situ formation of Sr-substituted HA on the surface during in vivo test. These results show that the interfacial layer protects the surface of the Mg-0.3Sr-0.3Ca alloy both in vitro and in vivo, and is the key factor in the bio-corrosion resistance of the alloy. Copyright © 2016 Elsevier B.V. All rights reserved.

Thyroid thermogenesis. Relationships between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in rat skeletal muscle.

PubMed Central

Asano, Y; Liberman, U A; Edelman, I S

1976-01-01

The effect of thyroid status on QO2, QO2 (t) and NaK-ATPase activity was examined in rat skeletal muscle. QO2(t) (i.e. Na+-transport-dependent respiration) was estimated with ouabain or Na+-free media supplemented with K+. In contrast to the effects of ouabain on ion composition, intracellular K+ was maintained at about 125 meq/liter, and intracellular Na+ was almost nil in the Na+-free media. The estimates of QO2(t) were independent of the considerable differences in tissue ion concentrations. The increase in QO2(t) account for 47% of the increase in QO2 in the transition from the hypothyroid to the euthyroid state and 84% of the increase in the transition from the euthyroid to the hyperthyroid state. Surgical thyroidectomy lowered NaK-ATPase activity of the microsomal fraction (expressed per milligram protein) 32%; injections of triodothyronine (T3) increased this activity 75% in initially hypothyroid rats and 26% in initially euthyroid rats. Thyroidectomy was attended by significant falls in serum Ca and Pi concentrations. Administration of T3 resulted in further declines in serum Ca and marked increases in serum Ps concentrations. Similar effects were seen in 131I-treated rats, but the magnitude of the declines in serum Ca were less. The effects of T3 on QO2, QO2(t), and NaK-ATPase activity of skeletal muscle were indistinguishable in the 131I-ablated and surgically thyroidectomized rats. In thyroidectomized or euthyroid rats given repeated doses of T3, QO2(t) and NaA-ATPase activity increased proportionately. In thyroidectomized rats injected with single doses of T3, either 10, 50, or 250 mug/100 g body wt, QO2(t) increased linearly with NaK-ATPase activity. The kinetics of the NaK-ATPase activity was assessed with an ATP-generating system. T3 elicited a significant increase in Vmax with no change in Km for ATP. PMID:130385

The development of binary Mg-Ca alloys for use as biodegradable materials within bone.

PubMed

Li, Zijian; Gu, Xunan; Lou, Siquan; Zheng, Yufeng

2008-04-01

Binary Mg-Ca alloys with various Ca contents were fabricated under different working conditions. X-ray diffraction (XRD) analysis and optical microscopy observations showed that Mg-xCa (x=1-3 wt%) alloys were composed of two phases, alpha (Mg) and Mg2Ca. The results of tensile tests and in vitro corrosion tests indicated that the mechanical properties could be adjusted by controlling the Ca content and processing treatment. The yield strength (YS), ultimate tensile strength (UTS) and elongation decreased with increasing Ca content. The UTS and elongation of as-cast Mg-1Ca alloy (71.38+/-3.01 MPa and 1.87+/-0.14%) were largely improved after hot rolling (166.7+/-3.01 MPa and 3+/-0.78%) and hot extrusion (239.63+/-7.21 MPa and 10.63+/-0.64%). The in vitro corrosion test in simulated body fluid (SBF) indicated that the microstructure and working history of Mg-xCa alloys strongly affected their corrosion behaviors. An increasing content of Mg2Ca phase led to a higher corrosion rate whereas hot rolling and hot extrusion could reduce it. The cytotoxicity evaluation using L-929 cells revealed that Mg-1Ca alloy did not induce toxicity to cells, and the viability of cells for Mg-1Ca alloy extraction medium was better than that of control. Moreover, Mg-1Ca alloy pins, with commercial pure Ti pins as control, were implanted into the left and right rabbit femoral shafts, respectively, and observed for 1, 2 and 3 months. High activity of osteoblast and osteocytes were observed around the Mg-1Ca alloy pins as shown by hematoxylin and eosin stained tissue sections. Radiographic examination revealed that the Mg-1Ca alloy pins gradually degraded in vivo within 90 days and the newly formed bone was clearly seen at month 3. Both the in vitro and in vivo corrosion suggested that a mixture of Mg(OH)2 and hydroxyapatite formed on the surface of Mg-1Ca alloy with the extension of immersion/implantation time. In addition, no significant difference (p>0.05) of serum magnesium was detected

Simultaneous observations of Ca II K and Mg II k in T Tauri stars

NASA Technical Reports Server (NTRS)

Calvet, N.; Basri, G.; Imhoff, C. L.; Giampapa, M. S.

1985-01-01

The first simultaneous, calibrated observations of the Ca II K and Mg II k resonance lines in T Tauri stars are presented. It is found that for T Tauri stars with mass greater than 1.5 solar mass, which have radiative cores and tend to be fast rotators, the k line seems to arise in an extended region (probably also responsible for the H-alpha emission), whereas the K line apparently originates closer to the highly inhomogeneous stellar surface. The lower mass stars, which are fully convective and tend to be slow rotators, are more easily described by a largely chromospheric model, consistent with main-sequence activity structures but at greater values of the nonradiative flux. The strongest emission-line stars in the low-mass group, however, are also likely to have extended k line regions.

Role of Y2O3, CaO, MgO additives on structural and microstructural behavior of zirconia/mullite aggregates

NASA Astrophysics Data System (ADS)

Mishra, D. K.; Prusty, Sasmita; Mohapatra, B. K.; Singh, S. K.; Behera, S. N.

2012-07-01

Zirconia mullite (MUZ), Y2O3-MUZ, CaO-MUZ and MgO-MUZ composites, synthesized through plasma fusion technique, are becoming important due to their commercial scale of production within five minutes of plasma treatment from sillimanite, zircon and alumina mixture. The X-ray diffraction studies reveal the monoclinic zirconia phase in MUZ composite whereas mixed monoclinic, tetragonal and cubic phases of zirconia have been observed in Y2O3, CaO, MgO added MUZ composites. The Y2O3, CaO and MgO additives act as sintering aids to favour the transformation and stabilisation of tetragonal and cubic zirconia phases at room temperature. These additives also play a key role in the development of various forms of microstructure to achieve dense MUZ composites.

Laser-induced chemiluminescence of NaMg

NASA Astrophysics Data System (ADS)

Benard, D. J.; Michels, H. H.

1982-03-01

An unstructured continuum emission around 670 nm was observed when Mg was added to an optically pumped heat pipe containing Na and K vapor, in good agreement with ab initio calculations of the NaMg potential energy curves. The corresponding excitation spectrum showed that the incident radiation was observed by NaK molecules (X → C transitions).

Quantifying Na(I)-insulin and K(I)-insulin non-covalent complexes by ESI-MS method and calculation of their equilibrium constants.

PubMed

Gülfen, Mustafa; Özdemir, Abdil; Lin, Jung-Lee; Chen, Chung-Hsuan

2017-10-01

In this study, the dissociation and formation equilibrium constants of Na(I)-insulin and K(I)-insulin complexes have been calculated after the quantifying them on ESI mass spectrometer. The ESI-MS spectra of the complexes were measured by using the solvents as 50% MeOH in water and 100% water. The effect of pH on the Na(I)-insulin and K(I)-insulin complex formation were examined. Serial binding of Na(I) and K(I) ions to the insulin molecule were observed in the ESI-MS measurements. The first formation equilibrium constants were calculated as K f1 : 5.48×10 3 1/M for Na(I)-insulin complex and K f1 : 4.87×10 3 1/M for K(I)-insulin in water. The binding capability of Na(I) ions to insulin molecule is higher than the capability of K(I) ions. In case of a comparison together with Ca(II)-insulin and Mg(II)-insulin, the formation equilibrium constants (K f1 ) are in order of Ca(II)-insulin>Mg(II)-insulin>Na(I)-insulin>K(I)-insulin in water. The results showed that Na(I) and K(I) ions are involved in the formation of the non-covalent complexes with insulin molecule, since high extracellular and intracellular concentrations of them in the body. Copyright © 2017 Elsevier B.V. All rights reserved.

Formation of hydroxyapatite onto glasses of the CaO-MgO-SiO2 system with B2O3, Na2O, CaF2 and P2O5 additives.

PubMed

Agathopoulos, S; Tulyaganov, D U; Ventura, J M G; Kannan, S; Karakassides, M A; Ferreira, J M F

2006-03-01

New bioactive glasses with compositions based on the CaO-MgO-SiO(2) system and additives of B(2)O(3), P(2)O(5), Na(2)O, and CaF(2) were prepared. The in vitro mineralization behaviour was tested by immersion of powders or bulk glasses in simulated body fluid (SBF). Monitoring of ionic concentrations in SBF and scanning electron microscopy (SEM) observations at the surface of the glasses were conducted over immersion time. Raman and infrared (IR) spectroscopy shed light on the structural evolution occurring at the surface of the glasses that leads to formation of hydroxyapatite.

Ehimeite, NaCa2Mg4CrSi6Al2O22(OH)2: The first Cr-dominant amphibole from the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan

NASA Astrophysics Data System (ADS)

Nishio-Hamane, Daisuke; Ohnishi, Masayuki; Minakawa, Tetsuo; Yamaura, Jun-Ichi; Saito, Shohei; Kadota, Ryo

The first Cr-dominant amphibole, ehimeite, ideally NaCa2Mg4CrSi6Al2O22(OH)2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kämmererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2Vcalc. = 53°. It has a Mohs’ hardness of 6 and densities of 3.08(3) g/cm3 (measured using heavy liquids) and 3.121 g/cm3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na0.88K0.07)Σ0.95(Ca1.89Na0.02Mg0.09)Σ2.00(Mg4.03Cr0.62Al0.19Fe3+0.07Fe2+0.07Ti0.03)Σ5.00(Si6.14Al1.86)Σ8.00O22(OH)2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa2Mg4(Cr, Al)Si6Al2O22(OH)2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) Å, b = 18.0009(12) Å, c = 5.2850(7) Å, β = 105.400(7)°, V = 909.6 (17) Å3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (Å), I/I0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.

Compositional dependence of bioactivity of glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2.

PubMed

Brink, M; Turunen, T; Happonen, R P; Yli-Urpo, A

1997-10-01

The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing < 59 mol % SiO2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and < 59 mol % SiO2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far.

Effect of zinc supplementation on the status of thyroid hormones and Na, K, And Ca levels in blood following ethanol feeding.

PubMed

Pathak, R; Dhawan, D; Pathak, A

2011-05-01

The influence of zinc (Zn) on the serum levels of triiodothyronine (T(3)), thyroxine (T(4)), thyroid-stimulating hormone (TSH) and sodium (Na), potassium (K), and calcium (Ca) was evaluated following ethanol toxicity to the rats. To achieve this, male Wistar rats (150-195 g) were given 3 ml of 30% ethanol orally, and zinc was given in the form of zinc sulfate (227 mg/l) in their drinking water daily for 8 weeks. Ethanol feeding resulted in a slight decrease in T(3) and T(4) levels and a significant increase in thyroid-stimulating hormone concentration, which may be due to the direct stimulatory effect of ethanol on thyroid. Interestingly, when zinc was given to these rats, all the above levels were brought quite close to their normal levels, thus indicating the positive role of zinc in thyroid hormone metabolism. Serum Zn and Ca levels were found to be reduced, but Na levels were raised upon ethanol feeding. Restoration of normal levels of these metals upon zinc supplementation to ethanol fed rats confirms that zinc has potential in alleviating some of the altered thyroid functions following ethanol administration.

Thermodynamic description of Tc(iv) solubility and hydrolysis in dilute to concentrated NaCl, MgCl2 and CaCl2 solutions.

PubMed

Yalçıntaş, Ezgi; Gaona, Xavier; Altmaier, Marcus; Dardenne, Kathy; Polly, Robert; Geckeis, Horst

2016-06-07

We present the first systematic investigation of Tc(iv) solubility, hydrolysis and speciation in dilute to concentrated NaCl, MgCl2 and CaCl2 systems, and comprehensive thermodynamic and activity models for the system Tc(4+)-H(+)-Na(+)-Mg(2+)-Ca(2+)-OH(-)-Cl(-)-H2O using both SIT and Pitzer approaches. The results are advancing the fundamental scientific understanding of Tc(iv) solution chemistry and are highly relevant in the applied context of nuclear waste disposal. The solubility of Tc(iv) was investigated in carbonate-free NaCl-NaOH (0.1-5.0 M), MgCl2 (0.25-4.5 M) and CaCl2 (0.25-4.5 M) solutions within 2 ≤ pHm≤ 14.5. Undersaturation solubility experiments were performed under an Ar atmosphere at T = 22 ± 2 °C. Strongly reducing conditions (pe + pHm≤ 2) were imposed with Na2S2O4, SnCl2 and Fe powder to stabilize technetium in the +IV redox state. The predominance of Tc(iv) in the aqueous phase was confirmed by solvent extraction and XANES/EXAFS spectroscopy. Solid phase characterization was accomplished after attaining thermodynamic equilibrium using XRD, SEM-EDS, XANES/EXAFS, TG-DTA and quantitative chemical analysis, and indicated that TcO2·0.6H2O(s) exerts solubility-control in all evaluated systems. The definition of the polyatomic Tc3O5(2+) species instead of TcO(2+) is favoured under acidic conditions, consistently with slope analysis (mTcvs. pHm) of the solubility data gained in this work and spectroscopic evidence previously reported in the literature. The additional formation of Tc(iv)-OH/O-Cl aqueous species in concentrated chloride media ([Cl(-)] = 9 M) and pHm≤ 4 is suggested by solubility and EXAFS data. The pH-independent behaviour of the solubility observed under weakly acidic to weakly alkaline pHm conditions can be explained with the equilibrium reaction TcO2·0.6H2O(s) + 0.4H2O(l) ⇔ TcO(OH)2(aq). Solubility data determined in dilute NaCl systems with pHm≥ 11 follow a well-defined slope of +1, consistent with the predominance of

Mechanisms for monovalent cation-dependent depletion of intracellular Mg2+:Na(+)-independent Mg2+ pathways in guinea-pig smooth muscle.

PubMed

Nakayama, Shinsuke; Nomura, Hideki; Smith, Lorraine M; Clark, Joseph F; Uetani, Tadayuki; Matsubara, Tatsuaki

2003-09-15

It has been suggested that magnesium deficiency is correlated with many diseases. 31P NMR experiments were carried out in order to investigate the effects of Na+ substitution on Mg2+ depletion in smooth muscle under divalent cation-free conditions. In the taenia of guinea-pig caeci, the intracellular free Mg2+ concentration ([Mg2+]i) was estimated from the chemical shifts of (1) the beta-ATP peak alone and (2) beta- and gamma-ATP peaks. Both estimations indicated that [Mg2+]i decreased only very slowly in Mg(2+)-free, Ca(2+)-free solutions in which Na+ was substituted with large cations such as NMDG (N-methyl-D-glucamine) and choline. Furthermore, the measurements of tension development supported the suggestion of preservation of intracellular Mg2+ with NMDG substitution. Substituting extracellular Na+ with the small cation, Li+, also shifted the beta-ATP peak towards a lower frequency, but the frequency shift was significantly less than that seen upon Na+ substitution with K+. The estimated [Mg2+]i depletion was, however, comparable with that seen after Na+ substitution with K+ using the titration curves of metal-free and Mg(2+)-bound ATP obtained in Li(+)-based model solutions. It was concluded that Mg2+ rapidly decreases only when small cations were the major electrolyte of the extracellular medium. Na+ substitutions with NMDG, choline or Li+ had little effect on intracellular ATP concentration after 100 min treatment.

Lead-free piezoelectric (K,Na)NbO3-based ceramic with planar-mode coupling coefficient comparable to that of conventional lead zirconate titanate

NASA Astrophysics Data System (ADS)

Ohbayashi, Kazushige; Matsuoka, Takayuki; Kitamura, Kazuaki; Yamada, Hideto; Hishida, Tomoko; Yamazaki, Masato

2017-06-01

We developed a (K,Na)NbO3-based lead-free piezoelectric ceramic with a KTiNbO5 system, (K1- x Na x )0.86Ca0.04Li0.02Nb0.85O3-δ-K0.85Ti0.85Nb1.15O5-BaZrO3-Fe2O3-MgO (K1- x N x N-NTK-FM). K1- x N x N-NTK-FM ceramic exhibits a very dense microstructure and a coupling coefficient of k p = 0.59, which is almost comparable to that of conventional lead zirconate titanate (PZT). The (K,Na)NbO3-based ceramic has the Γ15 mode for a wide x range. The nanodomains of orthorhombic (K,Na)NbO3 with the M3 mode coexist within the tetragonal Γ15 mode (K,Na)NbO3 matrix. Successive phase transition cannot occur with increasing x. The maximum k p is observed at approximately the minimum x required to generate the M3 mode phase. Unlike the behavior at the morphotropic phase boundary (MPB) in PZT, the characteristics of K1- x N x N-NTK-FM ceramic in this region changed moderately. This gentle phase transition seems to be a relaxor, although the diffuseness degree is not in line with this hypothesis. Furthermore, piezoelectric properties change from “soft” to “hard” upon the M3 mode phase aggregation.

Role of Na+/Ca2+ Exchangers in Therapy Resistance of Medulloblastoma Cells.

PubMed

Pelzl, Lisann; Hosseinzadeh, Zohreh; Al-Maghout, Tamer; Singh, Yogesh; Sahu, Itishri; Bissinger, Rosi; Schmidt, Sebastian; Alkahtani, Saad; Stournaras, Christos; Toulany, Mahmoud; Lang, Florian

2017-01-01

Alterations of cytosolic Ca2+-activity ([Ca2+]i) are decisive in the regulation of tumor cell proliferation, migration and survival. Transport processes participating in the regulation of [Ca2+]i include Ca2+ extrusion through K+-independent (NCX) and/or K+-dependent (NCKX) Na+/Ca2+-exchangers. The present study thus explored whether medulloblastoma cells express Na+/Ca2+-exchangers, whether expression differs between therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells, and whether Na+/Ca2+-exchangers participate in the regulation of cell survival. In therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells transcript levels were estimated by RT-PCR, protein abundance by Western blotting, cytosolic Ca2+-activity ([Ca2+]i) from Fura-2-fluorescence, Na+/ Ca2+-exchanger activity from the increase of [Ca2+]i (Δ[Ca2+]i) and from whole cell current (Ica) following abrupt replacement of Na+ containing (130 mM) and Ca2+ free by Na+ free and Ca2+ containing (2 mM) extracellular perfusate as well as cell death from PI -staining and annexin-V binding in flow cytometry. The transcript levels of NCX3, NCKX2, and NCKX5, protein abundance of NCX3, slope and peak of Δ[Ca2+]i as well as Ica were significantly lower in therapy sensitive D283 than in therapy resistant UW228-3 medulloblastoma cells. The Na+/Ca2+-exchanger inhibitor KB-R7943 (10 µM) significantly blunted Δ[Ca2+]i, and augmented the ionizing radiation-induced apoptosis but did not significantly modify clonogenicity of medulloblastoma cells. Apoptosis was further enhanced by NCX3 silencing. Na+/Ca2+-exchanger activity significantly counteracts apoptosis but does not significantly affect clonogenicity after radiation of medulloblastoma cells. © 2017 The Author(s). Published by S. Karger AG, Basel.

The Mg II h and k lines. II - Comparison with synthesized profiles and Ca II K. [solar spectra

NASA Technical Reports Server (NTRS)

Ayres, T. R.; Linsky, J. L.

1976-01-01

Measured high-dispersion center and limb profiles of the solar Mg II h and k resonance lines are compared with synthetic spectra computed with a partial-redistribution formalism and based on several upper-photosphere and lower-chromosphere temperature distributions. Profiles of the analogously formed Ca II K resonance line are also synthesized for the same atmospheric models. The spectrum-synthesis approach is outlined, and the collisional and fixed radiative rates appropriate to the adopted model atoms and solar atmosphere are discussed. It is found that the HSRA and VAL models predict systematically lower intensities in the h, k, and K inner wings than observed and that models with a somewhat higher minimum temperature (about 4450 K) can reproduce the measured inner wings and limb darkening. A 'Ca II' solar model with a minimum temperature of 4450 K is proposed as an alternative to the class of models based on continuum observations.

Modulation of K(Ca)3.1 channels by eicosanoids, omega-3 fatty acids, and molecular determinants.

PubMed

Kacik, Michael; Oliván-Viguera, Aida; Köhler, Ralf

2014-01-01

Cytochrome P450- and ω-hydrolase products (epoxyeicosatrienoic acids (EETs), hydroxyeicosatetraeonic acid (20-HETE)), natural omega-3 fatty acids (ω3), and pentacyclic triterpenes have been proposed to contribute to a wide range of vaso-protective and anti-fibrotic/anti-cancer signaling pathways including the modulation of membrane ion channels. Here we studied the modulation of intermediate-conductance Ca(2+)/calmodulin-regulated K(+) channels (K(Ca)3.1) by EETs, 20-HETE, ω3, and pentacyclic triterpenes and the structural requirements of these fatty acids to exert channel blockade. We studied modulation of cloned human hK(Ca)3.1 and the mutant hK(Ca)3.1(V275A) in HEK-293 cells, of rK(Ca)3.1 in aortic endothelial cells, and of mK(Ca)3.1 in 3T3-fibroblasts by inside-out and whole-cell patch-clamp experiments, respectively. In inside-out patches, Ca(2+)-activated hK(Ca)3.1 were inhibited by the ω3, DHA and α-LA, and the ω6, AA, in the lower µmolar range and with similar potencies. 5,6-EET, 8,9-EET, 5,6-DiHETE, and saturated arachidic acid, had no appreciable effects. In contrast, 14,15-EET, its stable derivative, 14,15-EEZE, and 20-HETE produced channel inhibition. 11,12-EET displayed less inhibitory activity. The K(Ca)3.1(V275A) mutant channel was insensitive to any of the blocking EETs. Non-blocking 5,6-EET antagonized the inhibition caused by AA and augmented cloned hK(Ca)3.1 and rK(Ca)3.1 whole-cell currents. Pentacyclic triterpenes did not modulate K(Ca)3.1 currents. Inhibition of K(Ca)3.1 by EETs (14,15-EET), 20-HETE, and ω3 critically depended on the presence of electron double bonds and hydrophobicity within the 10 carbons preceding the carboxyl-head of the molecules. From the physiological perspective, metabolism of AA to non-blocking 5,6,- and 8,9-EET may cause AA-de-blockade and contribute to cellular signal transduction processes influenced by these fatty acids.

Effect of MgO on Liquidus Temperatures in the ZnO-"FeO"-Al2O3-CaO-SiO2-MgO System in Equilibrium with Metallic Iron

NASA Astrophysics Data System (ADS)

Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

2011-06-01

The phase equilibria in the ZnO-"FeO"-Al2O3-CaO-SiO2-MgO system have been determined experimentally in equilibrium with metallic iron. Synthetic slags were equilibrated at a high temperature, quenched, and then the compositions of the phases in equilibrium were measured using electron probe X-ray microanalysis. Pseudoternary sections of the form ZnO-"FeO"-(Al2O3 + CaO + SiO2) for CaO/SiO2 = 0.71, (CaO + SiO2)/Al2O3 = 5 and fixed MgO concentrations of 2, 4, and 6 wt pct have been constructed. Wustite (Fe2+,Mg,Zn)O and spinel (Fe2+,Mg,Zn)O·(Al,Fe3+)2O3 are the major primary phases in the temperature and composition ranges investigated. The liquidus temperatures are increased by 140 K in the wustite primary phase field and by 70 K in the spinel primary phase field with the addition of 6 wt pct MgO in the slag. The partitioning of MgO and ZnO between the solid and liquid phases has been discussed.

Adjustment of the ratio of Ca/P in the ceramic coating on Mg alloy by plasma electrolytic oxidation

NASA Astrophysics Data System (ADS)

Yao, Zhongping; Li, Liangliang; Jiang, Zhaohua

2009-04-01

The ceramic coatings containing Ca and P were prepared on AZ91D Mg alloy by plasma electrolytic oxidation technique in NaOH system and Na 2SiO 3 system, respectively. The phase composition, morphology and the element distribution of the coatings was studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The corrosion resistance of the coatings was examined by polarizing curve methods in a 0.9% NaCl solution. In NaOH system, there were a large number of micro-holes distributing evenly on the surface of the coating, and the coating was mainly composed of Mg, Al, P and Ca. In Na 2SiO 3 system, the micro-holes in the coatings were reduced greatly in number and the distribution of the micro-holes was uneven, and the coating was mainly composed of Mg, Al, Si, P and Ca. The ratio of Ca/P in the coating can be controlled by the adjustment of the technique parameters to a certain extent. The adjustment of the concentration of Ca 2+ in the electrolyte was an effective method to change the ratio of Ca/P in the coating in both systems; the reaction time and the working voltage for the adjustment of the ratio of Ca/P in the coating was more suitable for the NaSi 2O 3 system than the NaOH system. The polarizing curve tests showed the coatings improved the corrosion resistance of the AZ91D Mg alloy in 0.9% NaCl solution by nearly two orders of magnitude.

Synthesis of Al₂Ca Dispersoids by Powder Metallurgy Using a Mg-Al Alloy and CaO Particles.

PubMed

Fujita, Junji; Umeda, Junko; Kondoh, Katsuyoshi

2017-06-28

The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4.7-at % Al atoms formed a supersaturated solid solution in the α-Mg matrix. Transmission electron microscopy-EDS and X-ray diffraction analyses on the AZ61B composite precursor with 10-vol % CaO particles obtained by heat treatment confirmed that CaO additives were thermally decomposed in the Mg-Al alloy, and the solid-soluted Ca atoms diffused along the α-Mg grain boundaries. Al atoms also diffused to the grain boundaries because of attraction to the Ca atoms resulting from a strong reactivity between Al and Ca. As a result, needle-like (Mg,Al)₂Ca intermetallics were formed as intermediate precipitates in the initial reaction stage during the heat treatment. Finally, the precipitates were transformed into spherical Al₂Ca particles by the substitution of Al atoms for Mg atoms in (Mg,Al)₂Ca after a long heat treatment.

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

NASA Astrophysics Data System (ADS)

Zöll, Klaus; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2018-02-01

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1-5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2. In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400 °C. By increasing the temperature up to 1425 °C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450 °C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35 μm in size could be retrieved from the 1425 °C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P 1 ̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1. Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium

Luminescence properties of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} (R{sup +}=Li{sup +}, Na{sup +}, and K{sup +}) red emission phosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Renping, E-mail: jxcrp@163.com; Chen, Guo; Yu, Xiaoguang

2014-12-15

A series of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, R{sup +}, and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} (R{sup +}=Li{sup +}, Na{sup +}, and K{sup +}) phosphors are synthesized by solid-state reaction method in air. All phosphors show bright red emissions centered at ∼617 nm upon excitation with UV light of 397 nm. Bi{sup 3+} is a sensitizer for the luminescence of Eu{sup 3+}, and can improve significantly the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} phosphor due to energy transfer between Bi{sup 3+} andmore » Eu{sup 3+} ions. The sensitization mechanism is investigated and discussed by energy level diagrams of Bi{sup 3+} and Eu{sup 3+} ions. R{sup +} ion is used as the charge compensator to improve the luminescence intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphors, and their PL intensities are enhanced in the sequence K{sup +}→Na{sup +}→Li{sup +}. These phosphors can be promising red emitting candidate for white LED with a ∼397 nm near UV chip excitation owing to the high brightness. - Graphical abstract: Energy transfer and charge compensation can enhance PL intensity of phosphors obviously. - Highlights: • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor is synthesized. • Energy transfer between Eu{sup 3+} and Bi{sup 3+} ions benefit PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Alkaline metal ions can further improve the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} phosphor may be promising red emitting candidate for white LED.« less

The measurement of sulfate mineral solubilities in the Na-K-Ca-Cl-SO 4-H 2O system at temperatures of 100, 150 and 200°C

NASA Astrophysics Data System (ADS)

Freyer, Daniela; Voigt, Wolfgang

2004-01-01

At T > 100°C development of thermodynamic models suffers from missing experimental data, particularly for solubilities of sulfate minerals in mixed solutions. Solubilities in Na +-K +-Ca 2+-Cl --SO 42-/H 2O subsystems were investigated at 150, 200°C and at selected compositions at 100°C. The apparatus used to examine solid-liquid phase equilibria under hydrothermal conditions has been described. In the system NaCl-CaSO 4-H 2O the missing anhydrite (CaSO 4) solubilities at high NaCl concentrations up to halite saturation have been determined. In the system Na 2SO 4-CaSO 4-H 2O the observed glauberite (Na 2SO 4 · CaSO 4) solubility is higher than that predicted by the high temperature model of Greenberg and Møller (1989), especially at 200°C. At high salt concentrations, solubilities of both anhydrite and glauberite increase with increasing temperature. Stability fields of the minerals syngenite (K 2SO 4 · CaSO 4 · H 2O) and goergeyite (K 2SO 4 · 5 CaSO 4 · H 2O) were determined, and a new phase was found at 200°C in the K 2SO 4-CaSO 4-H 2O system. Chemical and single crystal structure analysis give the formula K 2SO 4 · CaSO 4. The structure is isostructural with palmierite (K 2SO 4 · PbSO 4). The glaserite ("3 K 2SO 4 · Na 2SO 4") appears as solid solution in the system Na 2SO 4-K 2SO 4-H 2O. Its solubility and stoichiometry was determined as a function of solution composition.

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

NASA Astrophysics Data System (ADS)

Zolotov, Mikhail Yu.

2012-08-01

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance

Effects of NH4+, K+, Mg2+, and Ca2+ on the Cesium Adsorption/Desorption in Binding Sites of Vermiculitized Biotite.

PubMed

Yin, Xiangbiao; Wang, Xinpeng; Wu, Hao; Takahashi, Hideharu; Inaba, Yusuke; Ohnuki, Toshihiko; Takeshita, Kenji

2017-12-05

The reversibility of cesium adsorption in contaminated soil is largely dependent on its interaction with micaceous minerals, which may be greatly influenced by various cations. Herein, we systematically investigated the effects of NH 4 + , K + , Mg 2+ , and Ca 2+ on the adsorption/desorption of Cs + into different binding sites of vermiculitized biotite (VB). Original VB was initially saturated by NH 4 + , K + , or Mg 2+ ; we then evaluated the adsorption of Cs + on three treated VBs, and the desorption by extraction with NH 4 + , K + , Mg 2+ , or Ca 2+ was further evaluated. Our structural analysis and Cs + extractability determinations showed that NH 4 + and K + both collapsed the interlayers of VB, resulting in the dominant adsorption of Cs + to external surface sites on which Cs + was readily extracted by NH 4 + , K + , Mg 2+ , or Ca 2+ irrespective of their species, whereas Mg 2+ maintained the VB with expanded interlayers, leading to the overwhelming adsorption of Cs + in collapsed interlayer sites on which the Cs + desorption was difficult and varied significantly by the cations used in extraction. The order of Cs + extraction ability from the collapsed interlayers was K + ≫ Mg 2+ ≈ Ca 2+ ≫ NH 4 + . These results could provide important insights into Cs migration in soil and its decontamination for soil remediation.

Pressure probe and isopiestic psychrometer measure similar turgor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nonami, H.; Boyer, J.S.; Steudle, E.

1987-03-01

Turgor measured with a miniature pressure probe was compared to that measured with an isopiestic thermocouple psychrometer in mature regions of soybean (Glycine max (L.) Merr.) stems. The probe measured turgor directly in cells of intact stems whereas the psychrometer measured the water potential and osmotic potential of excised stem segments and turgor was calculated by difference. When care was taken to prevent dehydration when working with the pressure probe, and diffusive resistance and dilution errors with the psychrometer, both methods gave similar values of turgor whether the plants were dehydrating or rehydrating. This finding, together with the previously demonstratedmore » similarity in turgor measured with the isopiestic psychrometer and a pressure chamber, indicates that the pressure probe provides accurate measurements of turgor despite the need to penetrate the cell. On the other hand, it suggest that as long as precautions are taken to obtain accurate values for the water potential and osmotic potential, turgor can be determined by isopiestic psychrometry in tissues not accessible to the pressure probe for physical reasons.« less

Pressure probe and isopiestic psychrometer measure similar turgor.

PubMed

Nonami, H; Boyer, J S; Steudle, E

1987-03-01

Turgor measured with a miniature pressure probe was compared to that measured with an isopiestic thermocouple psychrometer in mature regions of soybean (Glycine max [L.] Merr.) stems. The probe measured turgor directly in cells of intact stems whereas the psychrometer measured the water potential and osmotic potential of excised stem segments and turgor was calculated by difference. When care was taken to prevent dehydration when working with the pressure probe, and diffusive resistance and dilution errors with the psychrometer, both methods gave similar values of turgor whether the plants were dehydrating or rehydrating. This finding, together with the previously demonstrated similarity in turgor measured with the isopiestic psychrometer and a pressure chamber, indicates that the pressure probe provides accurate measurements of turgor despite the need to penetrate the cell. On the other hand, it suggests that as long as precautions are taken to obtain accurate values for the water potential and osmotic potential, turgor can be determined by isopiestic psychrometry in tissues not accessible to the pressure probe for physical reasons.

Phase Diagram of Quaternary System NaBr-KBr-CaBr2-H2O at 323 K

NASA Astrophysics Data System (ADS)

Cui, Rui-Zhi; Wang, Wei; Yang, Lei; Sang, Shi-Hua

2018-03-01

The phase equilibria in the system NaBr-KBr-CaBr2-H2O at 323 K were studied using the isothermal dissolution equilibrium method. Using the experimental solubilities of salts data, phase diagram was constructed. The phase diagram have two invariant points, five univariant curves, and four crystallization fields. The equilibrium solid phases in the system are NaBr, NaBr · 2H2O, KBr, and CaBr2 · 4H2O. The solubilities of salts in the system at 323 K were calculated by Pitzer's equation. There is shown that the calculated solubilities agree well with experimental data.

Crystal structure and europium luminescence of NaMgH3-xFx

NASA Astrophysics Data System (ADS)

Pflug, Christian; Franz, Alexandra; Kohlmann, Holger

2018-02-01

The solid solution series NaMgH3-xFx (x = 0, 0.5, 1, 1.5, 2, 2.5, 3) was synthesized by solid-state reactions under hydrogen gas pressure from binary ionic hydrides, fluorides and magnesium. Rietveld refinement based on X-ray powder diffraction data revealed the GdFeO3-structure type for all compounds and a trend of lattice parameters according to Vegard's law. The anion distribution in NaMgD2F and NaMgD1.5F1.5 was found to be statistical by Rietveld refinement based on neutron powder diffraction data. Photoluminescence measurements on europium(II) substituted NaMgH3-xFx revealed a strong red shift of the emission wavelength (λem = 665 nm for NaMgH2F:Eu) in comparison to violet emitting NaMgF3:Eu.

A Structural Molar Volume Model for Oxide Melts Part I: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 Melts—Binary Systems

NASA Astrophysics Data System (ADS)

Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

2016-04-01

A structural molar volume model was developed to accurately reproduce the molar volume of molten oxides. As the non-linearity of molar volume is related to the change in structure of molten oxides, the silicate tetrahedral Q-species, calculated from the modified quasichemical model with an optimized thermodynamic database, were used as basic structural units in the present model. Experimental molar volume data for unary and binary melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system were critically evaluated. The molar volumes of unary oxide components and binary Q-species, which are model parameters of the present structural model, were determined to accurately reproduce the experimental data across the entire binary composition in a wide range of temperatures. The non-linear behavior of molar volume and thermal expansivity of binary melt depending on SiO2 content are well reproduced by the present model.

Effect of Bath Temperature on Cooling Performance of Molten Eutectic NaNO3-KNO3 Quench Medium for Martempering of Steels

NASA Astrophysics Data System (ADS)

Pranesh Rao, K. M.; Narayan Prabhu, K.

2017-10-01

Martempering is an industrial heat treatment process that requires a quench bath that can operate without undergoing degradation in the temperature range of 423 K to 873 K (150 °C to 600 °C). The quench bath is expected to cool the steel part from the austenizing temperature to quench bath temperature rapidly and uniformly. Molten eutectic NaNO3-KNO3 mixture has been widely used in industry to martemper steel parts. In the present work, the effect of quench bath temperature on the cooling performance of a molten eutectic NaNO3-KNO3 mixture has been studied. An Inconel ASTM D-6200 probe was heated to 1133 K (860 °C) and subsequently quenched in the quench bath maintained at different temperatures. Spatially dependent transient heat flux at the metal-quenchant interface for each bath temperature was calculated using inverse heat conduction technique. Heat transfer occurred only in two stages, namely, nucleate boiling and convective cooling. The mean peak heat flux ( q max) decreased with increase in quench bath temperature, whereas the mean surface temperature corresponding to q max and mean surface temperature at the start of convective cooling stage increased with increase in quench bath temperature. The variation in normalized cooling parameter t 85 along the length of the probe increased with increase in quench bath temperature.

Seawater Mg/Ca controls polymorph mineralogy of microbial CaCO3: a potential proxy for calcite-aragonite seas in Precambrian time.

PubMed

Ries, J B; Anderson, M A; Hill, R T

2008-03-01

A previously published hydrothermal brine-river water mixing model driven by ocean crust production suggests that the molar Mg/Ca ratio of seawater (mMg/Ca(sw)) has varied significantly (approximately 1.0-5.2) over Precambrian time, resulting in six intervals of aragonite-favouring seas (mMg/Ca(sw) > 2) and five intervals of calcite-favouring seas (mMg/Ca(sw) < 2) since the Late Archaean. To evaluate the viability of microbial carbonates as mineralogical proxy for Precambrian calcite-aragonite seas, calcifying microbial marine biofilms were cultured in experimental seawaters formulated over the range of Mg/Ca ratios believed to have characterized Precambrian seawater. Biofilms cultured in experimental aragonite seawater (mMg/Ca(sw) = 5.2) precipitated primarily aragonite with lesser amounts of high-Mg calcite (mMg/Ca(calcite) = 0.16), while biofilms cultured in experimental calcite seawater (mMg/Ca(sw) = 1.5) precipitated exclusively lower magnesian calcite (mMg/Ca(calcite) = 0.06). Furthermore, Mg/Ca(calcite )varied proportionally with Mg/Ca(sw). This nearly abiotic mineralogical response of the biofilm CaCO3 to altered Mg/Ca(sw) is consistent with the assertion that biofilm calcification proceeds more through the elevation of , via metabolic removal of CO2 and/or H+, than through the elevation of Ca2+, which would alter the Mg/Ca ratio of the biofilm's calcifying fluid causing its pattern of CaCO3 polymorph precipitation (aragonite vs. calcite; Mg-incorporation in calcite) to deviate from that of abiotic calcification. If previous assertions are correct that the physicochemical properties of Precambrian seawater were such that Mg/Ca(sw) was the primary variable influencing CaCO3 polymorph mineralogy, then the observed response of the biofilms' CaCO3 polymorph mineralogy to variations in Mg/Ca(sw), combined with the ubiquity of such microbial carbonates in Precambrian strata, suggests that the original polymorph mineralogy and Mg/Ca(calcite )of well

Investigation of properties of the Ca2+ influx and of the Ca2+-activated K+ efflux (Gárdos effect) in vanadate-treated and ATP-depleted human red blood cells.

PubMed

Kaiserová, K; Lakatos, B; Peterajová, E; Orlický, J; Varecka, L'

2002-12-01

In this study the properties of the 45Ca2+ influx in human red blood cells (RBC) induced by NaVO3 or ATP-depletion were compared. Both NaVO3-induced and ATP-depletion-induced 45Ca2+ influxes were in the range 10(-6)-10(-5) mol Ca2+ x l(-1)cells x h(-1). The saturatability of ATP-depletion-induced 45Ca2+ influx with Ca2+ was much less pronounced than that of NaVO3-induced 45Ca2+ influx. The NaVO3-induced Ca2+ influx was sensitive to nifedipine (IC50 = 50 micromol/l) and Cu2+ (IC50 = 9 micromol/l) but these inhibitors had only a marginal effect when ATP-depletion was used as the Ca2+ influx inducer. On the other hand, polymyxin B (PXB) (1-5 mg/ml) strongly stimulated the ATP-depletion-induced 45Ca2+ influx whereas its effect on the NaVO3-induced Ca2+ influx was biphasic, with about 10% stimulation at lower PXB concentrations and an inhibition of 40% at higher concentrations. SDS-PAGE revealed that both NaVO3 and PXB induced changes in the protein phosphorylation pattern in the presence of Ca2+. NaVO3 stimulated the phosphorylation of several proteins and this effect was counteracted by PXB. The comparison of the kinetics and temperature dependencies of the Gárdos effect induced by NaVO3 and the ATP-depletion showed marked differences. The ability of NaVO3 to induce the Gárdos effect dramatically increased in ATP-depleted cells. These findings indicate that the 45Ca2+ influxes preceding the activation of the Ca2+-activated K+ efflux (Gárdos effect) stimulated by NaVO3 and by ATP-depletion, are mediated by different transport pathways. In addition, obtained results demonstrate that ATP-depletion and NaVO3-treatment exert additive action in triggering the Gárdos effect.

Thermodynamic modeling of hydrogen storage capacity in Mg-Na alloys.

PubMed

Abdessameud, S; Mezbahul-Islam, M; Medraj, M

2014-01-01

Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.

[Properties and localization of Mg- and Ca-ATpase activities in wheat embryo cell nuclei].

PubMed

Vasil'eva, N A; Belkina, G G; Stepanenko, S Y; Atalykova, F I; Oparin, A I

1978-05-01

The isolated nuclei of wheat embryo possess the ATPase activity. The addition of Mg2+ and Ca2+ significantly increases the activities of nuclear ATPases, whereas Hg2+, Cu2+ and Mn2+ inhibit the activity. The activating effect of Mg2+ is enhanced by an addition of Na and K ions. The activity of wheat embryo nuclear Mg-ATPase is higher than its Ca-ATPase activity; both ATPases also differ in their pH optima. Separation of total nuclear protein according to the solubility of its individual protein components in wheat and strong salt solutions, using the detergents, as well as ammonium sulfate precipitation and dialysis do not result in separation of Mg-activated and Ca-activated ATPases, although their levels of activities and ratios change in the course of fractionation. The Mg- and Ca-ATPase activities of the wheat embryo nuclei were found in the nuclear fraction of albumin, in nonhistone proteins and nuclear membranes. In the albumin nuclear fraction and subfractions of non-histone proteins the higher level of activity is observed in Ca-ATPase, whereas in the nuclei and soluble fractions of residual proteins in Mg-ATPase.

Involvement of dominant-negative spliced variants of the intermediate conductance Ca2+-activated K+ channel, K(Ca)3.1, in immune function of lymphoid cells.

PubMed

Ohya, Susumu; Niwa, Satomi; Yanagi, Ayano; Fukuyo, Yuka; Yamamura, Hisao; Imaizumi, Yuji

2011-05-13

The intermediate conductance Ca(2+)-activated K(+) channel (IK(Ca) channel) encoded by K(Ca)3.1 is responsible for the control of proliferation and differentiation in various types of cells. We identified novel spliced variants of K(Ca)3.1 (human (h) K(Ca)3.1b) from the human thymus, which were lacking the N-terminal domains of the original hK(Ca)3.1a as a result of alternative splicing events. hK(Ca)3.1b was significantly expressed in human lymphoid tissues. Western blot analysis showed that hK(Ca)3.1a proteins were mainly expressed in the plasma membrane fraction, whereas hK(Ca)3.1b was in the cytoplasmic fraction. We also identified a similar N terminus lacking K(Ca)3.1 variants from mice and rat lymphoid tissues (mK(Ca)3.1b and rK(Ca)3.1b). In the HEK293 heterologous expression system, the cellular distribution of cyan fluorescent protein-tagged hK(Ca)3.1a and/or YFP-tagged hK(Ca)3.1b isoforms showed that hK(Ca)3.1b suppressed the localization of hK(Ca)3.1a to the plasma membrane. In the Xenopus oocyte translation system, co-expression of hK(Ca)3.1b with hK(Ca)3.1a suppressed IK(Ca) channel activity of hK(Ca)3.1a in a dominant-negative manner. In addition, this study indicated that up-regulation of mK(Ca)3.1b in mouse thymocytes differentiated CD4(+)CD8(+) phenotype thymocytes into CD4(-)CD8(-) ones and suppressed concanavalin-A-stimulated thymocyte growth by down-regulation of mIL-2 transcripts. Anti-proliferative effects and down-regulation of mIL-2 transcripts were also observed in mK(Ca)3.1b-overexpressing mouse thymocytes. These suggest that the N-terminal domain of K(Ca)3.1 is critical for channel trafficking to the plasma membrane and that the fine-tuning of IK(Ca) channel activity modulated through alternative splicing events may be related to the control in physiological and pathophysiological conditions in T-lymphocytes.

Surface tensions of inorganic multicomponent aqueous electrolyte solutions and melts.

PubMed

Dutcher, Cari S; Wexler, Anthony S; Clegg, Simon L

2010-11-25

A semiempirical model is presented that predicts surface tensions (σ) of aqueous electrolyte solutions and their mixtures, for concentrations ranging from infinitely dilute solution to molten salt. The model requires, at most, only two temperature-dependent terms to represent surface tensions of either pure aqueous solutions, or aqueous or molten mixtures, over the entire composition range. A relationship was found for the coefficients of the equation σ = c(1) + c(2)T (where T (K) is temperature) for molten salts in terms of ion valency and radius, melting temperature, and salt molar volume. Hypothetical liquid surface tensions can thus be estimated for electrolytes for which there are no data, or which do not exist in molten form. Surface tensions of molten (single) salts, when extrapolated to normal temperatures, were found to be consistent with data for aqueous solutions. This allowed surface tensions of very concentrated, supersaturated, aqueous solutions to be estimated. The model has been applied to the following single electrolytes over the entire concentration range, using data for aqueous solutions over the temperature range 233-523 K, and extrapolated surface tensions of molten salts and pure liquid electrolytes: HCl, HNO(3), H(2)SO(4), NaCl, NaNO(3), Na(2)SO(4), NaHSO(4), Na(2)CO(3), NaHCO(3), NaOH, NH(4)Cl, NH(4)NO(3), (NH(4))(2)SO(4), NH(4)HCO(3), NH(4)OH, KCl, KNO(3), K(2)SO(4), K(2)CO(3), KHCO(3), KOH, CaCl(2), Ca(NO(3))(2), MgCl(2), Mg(NO(3))(2), and MgSO(4). The average absolute percentage error between calculated and experimental surface tensions is 0.80% (for 2389 data points). The model extrapolates smoothly to temperatures as low as 150 K. Also, the model successfully predicts surface tensions of ternary aqueous mixtures; the effect of salt-salt interactions in these calculations was explored.

Comparative evaluation of some commercially available brands of pharmaceutical preparations for Na, K and Mg concentrations.

PubMed

Hayat, Sikander; Chughtai, Muhammad Ismail; Ansari, Tariq Mahmood; Kamal, Ghulam Mustafa

2012-04-01

A study was carried out to investigate the concentrations of macro-elements (Na(+), K(+) and Mg(+2)) in twelve commercially available pharmaceutical preparations used as sex stimulant, by Atomic Absorption Spectrophotometer. A wet digestion method was adopted to prepare the samples. The results indicated that sodium concentration was maximum (3702 ± 29 μg g(-1)) in LB and minimum (495 ± 06 μg g(-1)) in H-E-H. Potassium concentration was maximum (6337 ± 13 μg g(-1)) in NBA while minimum (150 ± 06 μg g(-1)) in ZGRA. Magnesium concentration was maximum in V-100 (9226 ± 11 μg g(-1)) and minimum in FGRA (1194 ± 25 μg g(-1)). The concentration of macro-elements in the imported herbal preparations was in the order of Mg and in the local herbal preparations as follows: Mg. Some of these herbal preparations contain high level of macro-elements than the recommended daily dietary allowances. The excessive use of such preparations may cause severe allergic reactions, kidney damage and pulmonary atherosclerosis.

Effects of Processing Parameters on the Synthesis of (K0.5Na0.5)NbO3 Nanopowders by Reactive High-Energy Ball Milling Method

PubMed Central

Duc Van, Nguyen

2014-01-01

The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C. PMID:24592146

Effects of processing parameters on the synthesis of (K0.5Na0.5)NbO3 nanopowders by reactive high-energy ball milling method.

PubMed

Nguyen, Duc Van

2014-01-01

The effects of ball milling parameters, namely, the ball-to-powder mass ratio and milling speed, on the synthesis of (K0.5Na0.5)NbO3 nanopowders by high-energy ball milling method from a stoichiometric mixture containing Na2CO3, K2CO3, and Nb2O5 were investigated in this paper. The results indicated that the single crystalline phase of (K0.5Na0.5)NbO3 was received in as-milled samples synthesized using optimized ball-to-powder mass ratio of 35 : 1 and at a milling speed of 600 rpm for 5 h. In the optimized as-milled samples, no remaining alkali carbonates that can provide the volatilizable potassium-containing species were found and (K0.5Na0.5)NbO3 nanopowders were readily obtained via the formation of an intermediate carbonato complex. This complex was mostly transformed into (K0.5Na0.5)NbO3 at temperature as low as 350°C and its existence was no longer detected at spectroscopic level when calcination temperature crossed over 700°C.

Enhanced heavy metal immobilization in soil by grinding with addition of nanometallic Ca/CaO dispersion mixture.

PubMed

Mallampati, Srinivasa Reddy; Mitoma, Yoshiharu; Okuda, Tetsuji; Sakita, Shogo; Kakeda, Mitsunori

2012-10-01

This study investigated the use of a nanometallic Ca and CaO dispersion mixture for the immobilization of heavy metals (As, Cd, Cr and Pb) in contaminated soil. Simple grinding achieved 85-90% heavy metal immobilization, but it can be enhanced further to 98-100% by addition of a nanometallic Ca/CaO dispersion mixture produced by grinding. Observations using SEM-EDS elemental maps and semi-quantitative analysis showed that the amounts of As, Cd, Cr, and Pb measurable on the soil particle surface decrease after nanometallic Ca/CaO treatment. The leachable heavy metal concentrations were reduced after nanometallic Ca/CaO treatment to concentrations lower than the Japan soil elution standard regulatory threshold: <0.01 mg L(-1) for As, Cd, and Pb; and 0.05 mg L(-1) for Cr. Effects of soil moisture and pH on heavy metal immobilization were not strongly influenced. The most probable mechanisms for the enhancement of heavy metal immobilization capacity with nanometallic Ca/CaO treatment might be due to adsorption and entrapment of heavy metals into newly formed aggregates, thereby prompting aggregation of soil particles and enclosure/binding with Ca/CaO-associated immobile salts. Results suggest that the nanometallic Ca/CaO mixture is suitable for use in immobilization of heavy-metal-contaminated soil under normal moisture conditions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Feshbach spectroscopy and dual-species Bose-Einstein condensation of 23Na-39K mixtures

NASA Astrophysics Data System (ADS)

Schulze, Torben A.; Hartmann, Torsten; Voges, Kai K.; Gempel, Matthias W.; Tiemann, Eberhard; Zenesini, Alessandro; Ospelkaus, Silke

2018-02-01

We present measurements of interspecies Feshbach resonances and subsequent creation of dual-species Bose-Einstein condensates of 23Na and 39K. We prepare both optically trapped ensembles in the spin state |f =1 ,mf=-1 > and perform atom loss spectroscopy in a magnetic field range from 0 to 700 G . The observed features include several s -wave poles and a zero crossing of the interspecies scattering length as well as inelastic two-body contributions in the M =mNa+mK=-2 submanifold. We identify and discuss the suitability of different magnetic field regions for the purposes of sympathetic cooling of 39K and achieving dual-species degeneracy. Two condensates are created simultaneously by evaporation at a magnetic field of about 150 G , which provides sizable intra- and interspecies scattering rates needed for fast thermalization. The impact of the differential gravitational sag on the miscibility criterion for the mixture is discussed. Our results serve as a promising starting point for the magnetoassociation into quantum degenerate 23Na39K Feshbach molecules.

Manipulating the alkali metal charge compensation and tungsten oxide to continuously enhance the red fluorescence in (Li,Na,K)Ca(Mo,W)O4:Eu3+ solid solution compounds

NASA Astrophysics Data System (ADS)

Xie, Wei; Li, Jiaxin; Tian, Canxin; Wang, Zesong; Xie, Mubiao; Zou, Changwei; Sun, Guohuan; Kang, Fengwen

2018-02-01

When compared to other phosphors typically the blue and green phosphors, red phosphors, which can be used for white light-emitting diodes (wLEDs), always suffer from various problems such as higher cost, lower luminescence efficiency and bad thermal stability. And thus, great interests have been paid to how to enhance the red fluorescence intensity in the recent years. Here we report on a red-emitting solid solutions, (Li,Na,K)Ca(Mo,W)O4:Eu3+, which enable exhibiting continuous Eu3+ emission enhancement through manipulating the alkali metal ions and the relative content ratios between tungsten and molybdenum oxides. X-ray powder diffraction (XRD) has been employed to check the phase purity, and results show that all samples crystallize in a scheelite structure with space group of I41/a (No.88). A regular blue-shifting of XRD peaks, which indicates the increase of crystal plane spacing, appears as the alkali cationic radius increases from 0.92 Å (for Li), 1.18 Å (for Na) and to 1.38 Å (for K). Replacing Mo ion (0.41 Å) by W ion (0.42 Å) enables not only forming the solid solution compounds (Li,Na,K)Ca(Mo,W)O4:Eu3+, but also blue-shifting the XRD position. Similar to the XRD position shifting, our samples also exhibit the regular change in the photoluminescence (PL) spectra, in which the charge transfer (CT) band position as the alkali cationic radii increase from Li, Na and to K and further from Mo to W shows a continuous red-shifting behavior. As for the CT and Eu3+ intensity, our experimental results show that the alkali ion that corresponds to the maximum intensity is Li, and this intensity can be further enhanced by adding W. In coincidence with the change in the excitation spectral intensity, the continuous enhanced Eu3+ emission intensity can be observed up excitation at the CT band and Eu3+ lines. We have discussed the above CT band shifting and Eu3+ fluorescence enhancement and give a feasible mechanism profile that base on the energy transfer from CT

Effects of Partial Substitutions of NaCl with KCl, CaSO4 and MgSO4 on the Quality and Sensorial Properties of Pork Patties.

PubMed

Davaatseren, Munkhtugs; Chun, Ji-Yeon; Cho, Hyung-Yong; Min, Sang-Gi; Choi, Mi-Jung

2014-01-01

This study investigated the effects of NaCl replacers (KCl, CaSO4, and MgSO4) on the quality and sensorial properties of pork patty. In the characteristics of spray-dried salt particles, KCl showed the largest particle size with low viscosity in solution. Meanwhile CaSO4 treatment resulted in the smallest particle size and the highest viscosity (p<0.05). In comparison of the qualities of pork patties manufactured by varying level of Na replacers, MgSO4 treatment exhibited low cooking loss comparing to control (p<0.05). Textural properties of KCl and MgSO4 treatments showed similar pattern, i.e., low level of the replacers caused harder and less adhesive texture than those of control (p<0.05), whereas the hardness of these products was not different with control when the replacers were added more than 1.0%. The addition of CaSO4 also manifested harder and less adhesive than control (p<0.05), but the textural properties of CaSO4 treatment was not affected by level of Ca-salt. Eventually, sensorial properties indicated that KCl and CaSO4 influenced negative effects on pork patties. In contrast, MgSO4 showed better sensorial properties in juiciness intensity, tenderness intensity as well as overall acceptability than control, reflecting that MgSO4 was an effective Na-replacer in meat product formulation.

The role of sodium hydrosulfide in attenuating the aging process via PI3K/AKT and CaMKKβ/AMPK pathways.

PubMed

Chen, Xubo; Zhao, Xueyan; Cai, Hua; Sun, Haiying; Hu, Yujuan; Huang, Xiang; Kong, Wen; Kong, Weijia

2017-08-01

Age-related dysfunction of the central auditory system, known as central presbycusis, is characterized by defects in speech perception and sound localization. It is important to determine the pathogenesis of central presbycusis in order to explore a feasible and effective intervention method. Recent work has provided fascinating insight into the beneficial function of H 2 S on oxidative stress and stress-related disease. In this study, we investigated the pathogenesis of central presbycusis and tried to explore the mechanism of H 2 S action on different aspects of aging by utilizing a mimetic aging rat and senescent cellular model. Our results indicate that NaHS decreased oxidative stress and apoptosis levels in an aging model via CaMKKβ and PI3K/AKT signaling pathways. Moreover, we found that NaHS restored the decreased activity of antioxidants such as GSH, SOD and CAT in the aging model in vivo and in vitro by regulating CaMKKβ and PI3K/AKT. Mitochondria function was preserved by NaHS, as indicated by the following: DNA POLG and OGG-1, the base excision repair enzymes in mitochondrial, were upregulated; OXPHOS activity was downregulated; mitochondrial membrane potential was restored; ATP production was increased; and mtDNA damage, indicated by the common deletion (CD), declined. These effects were also achieved by activating CaMKKβ/AMPK and PI3K/AKT signaling pathways. Lastly, protein homeostasis, indicated by HSP90 alpha, was strengthened by NaHS via CaMKKβ and PI3K/AKT. Our findings demonstrate that the ability to resist oxidative stress and mitochondria function are both decreased as aging developed; however, NaHS, a novel free radical scavenger and mitochondrial protective agent, precludes the process of oxidative damage by activating CaMKKβ and PI3K/AKT. This study might provide a therapeutic target for aging and age-related disease. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Pressure Probe and Isopiestic Psychrometer Measure Similar Turgor 1

PubMed Central

Nonami, Hiroshi; Boyer, John S.; Steudle, Ernst

1987-01-01

Turgor measured with a miniature pressure probe was compared to that measured with an isopiestic thermocouple psychrometer in mature regions of soybean (Glycine max [L.] Merr.) stems. The probe measured turgor directly in cells of intact stems whereas the psychrometer measured the water potential and osmotic potential of excised stem segments and turgor was calculated by difference. When care was taken to prevent dehydration when working with the pressure probe, and diffusive resistance and dilution errors with the psychrometer, both methods gave similar values of turgor whether the plants were dehydrating or rehydrating. This finding, together with the previously demonstrated similarity in turgor measured with the isopiestic psychrometer and a pressure chamber, indicates that the pressure probe provides accurate measurements of turgor despite the need to penetrate the cell. On the other hand, it suggests that as long as precautions are taken to obtain accurate values for the water potential and osmotic potential, turgor can be determined by isopiestic psychrometry in tissues not accessible to the pressure probe for physical reasons. PMID:16665293

Preparation of MgO-SnO2-TiO2 Materials and Their Corrosion in Na3AlF6-AlF3-K3AlF6 Bath

NASA Astrophysics Data System (ADS)

Xu, Yibiao; Li, Yawei; Sang, Shaobai; Ren, Bo; Qin, Qingwei; Yang, Jianhong

2015-01-01

New types of refractory materials need to be developed for designing the so-called ledge-free sidewalls of the Hall-Héroult cell for aluminum extraction, which are currently constructed using Si3N4 bonded SiC refractories. In the present paper, MgO-based materials as potential candidate sidewalls were prepared using fused magnesia, tin dioxide, and anatase powder as starting materials. The reaction sintering process of the MgO-SnO2-TiO2 materials was investigated by means of X-ray diffraction and scanning electron microscope (SEM). All the specimens were corroded in a Na3AlF6-AlF3-K3AlF6 bath to assess the electrolyte corrosion resistance. The results show that reaction sintering occurs in the MgO-SnO2-TiO2 system in the range of 1373 K to 1873 K (1100 °C to 1600 °C). Firstly, MgO reacts separately with TiO2 and SnO2 to produce the Mg2TiO4 and Mg2SnO4 phases at 1373 K (1100 °C), which in turn react to form the Mg2Ti x Sn1-x O4 composite spinel at temperatures above 1373 K (1100 °C). All the specimens prepared are composed of the composite spinel and periclase phases. Increasing the SnO2 addition from 2 to 10 wt pct enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed composite spinels in the MgO matrix, but the density of the specimen decreases when the amount of SnO2 added is higher than 10 wt pct due to larger volume expansion and agglomeration of the composite spinel. The MgO-SnO2-TiO2 refractories prepared exhibit good corrosion resistance to the electrolyte melts owing to their high density and formation of the composite spinel in the specimens. Their corrosion resistance increases progressively with the increase in the SnO2 addition owing to the formation of more chemically stable composite spinel.

Nitrogen conservation in simulated food waste aerobic composting process with different Mg and P salt mixtures.

PubMed

Li, Yu; Su, Bensheng; Liu, Jianlin; Du, Xianyuan; Huang, Guohe

2011-07-01

To assess the effects of three types of Mg and P salt mixtures (potassium phosphate [K3PO4]/magnesium sulfate [MgSO4], potassium dihydrogen phosphate [K2HPO4]/MgSO4, KH2PO4/MgSO4) on the conservation of N and the biodegradation of organic materials in an aerobic food waste composting process, batch experiments were undertaken in four reactors (each with an effective volume of 30 L). The synthetic food waste was composted of potatoes, rice, carrots, leaves, meat, soybeans, and seed soil, and the ratio of C and N was 17:1. Runs R1-R3 were conducted with the addition of K3PO4/ MgSO4, K2HPO4/MgSO4, and KH2PO4/MgSO4 mixtures, respectively; run R0 was a blank performed without the addition of Mg and P salts. After composting for 25 days, the degrees of degradation of the organic materials in runs R0-R3 were 53.87, 62.58, 59.14, and 49.13%, respectively. X-ray diffraction indicated that struvite crystals were formed in runs R1-R3 but not in run R0; the gaseous ammonia nitrogen (NH3-N) losses in runs R0-R3 were 21.2, 32.8, 12.6, and 3.5% of the initial total N, respectively. Of the tested Mg/P salt mixtures, the K2HPO4/ MgSO4 system provided the best combination of conservation of N and biodegradation of organic materials in this food waste composting process.

Near-UV and blue wavelength excitable Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} high efficiency red phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khanna, A.; Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180; Dutta, P.S., E-mail: duttap@rpi.edu

Red phosphors with narrow emission around 615 nm (with FWHM~5–10 nm) having chemical compositions of A{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} (A=Mg, Sr) have been found to exhibit the highest luminescence amongst the molybdate–tungstate family when excited by sources in the 380–420 nm wavelength range. Thus they are most suitable for enhancing color rendering index and lowering color temperature in phosphor converted white LEDs (pc-WLEDs) with near-UV/blue LED excitation sources. The excitation band edge in the near UV/blue wavelength in the reported phosphor has been attributed to the coordination environment of the transition metal ionmore » (Mo{sup 6+}, W{sup 6+}) and host crystal structure. Furthermore the quantum efficiency of the phosphors has been enhanced by adjusting activator concentration, suitable compositional alloying using substitutional alkaline earth metal cations and charge compensation mechanisms. - Graphical abstract: The charge transfer excitation of orthorhombic Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} is significantly higher than tetragonal CaMoO{sub 4}: Eu{sup 3+} phosphors making Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} prime candidates for fabrication of warm white phosphor-converted LEDs. - Highlights: • LED excitable Mg{sub 0.6}Ca{sub 2.16}Mo{sub 0.2}W{sub 0.8}O{sub 6}: Eu{sub 0.12}{sup 3+}/Na{sub 0.12}{sup +} phosphors were synthesized. • These phosphors are 10 times more intense than CaMoO{sub 4}: Eu{sup 3+} red phosphors. • Their intensity and efficiency were enhanced by materials optimization techniques. • Such techniques include compositional alloying, charge compensation, etc.« less

Description and crystal structure of albrechtschraufite, MgCa4F2[UO2(CO3)3]2ṡ17-18H2O

NASA Astrophysics Data System (ADS)

Mereiter, Kurt

2013-04-01

Albrechtschraufite, MgCa4F2[UO2(CO3)3]2ṡ17-18H2O, triclinic, space group Pī, a = 13.569(2), b = 13.419(2), c = 11.622(2) Å, α = 115.82(1), β = 107.61(1), γ = 92.84(1)° (structural unit cell, not reduced), V = 1774.6(5) Å3, Z = 2, D c = 2.69 g/cm3 (for 17.5 H2O), is a mineral that was found in small amounts with schröckingerite, NaCa3F[UO2(CO3)3](SO4)ṡ10H2O, on a museum specimen of uranium ore from Joachimsthal (Jáchymov), Czech Republic. The mineral forms small grain-like subhedral crystals (≤ 0.2 mm) that resemble in appearance liebigite, Ca2[UO2(CO3)3]ṡ ~ 11H2O. Colour pale yellow-green, luster vitreous, transparent, pale bluish green fluorescence under ultraviolet light. Optical data: Biaxial negative, nX = 1.511(2), nY = 1.550(2), nZ = 1.566(2), 2 V = 65(1)° ( λ = 589 nm), r < v weak. After qualitative tests had shown the presence of Ca, U, Mg, CO2 and H2O, the chemical formula was determined by a crystal structure analysis based on X-ray four-circle diffractometer data. The structure was later on refined with data from a CCD diffractometer to R1 = 0.0206 and wR2 = 0.0429 for 9,236 independent observed reflections. The crystal structure contains two independent [UO2(CO3)3]4- anions of which one is bonded to two Mg and six Ca while the second is bonded to only one Mg and three Ca. Magnesium forms a MgF2(Ocarbonate)3(H2O) octahedron that is linked via the F atoms with three Ca atoms so as to provide each F atom with a flat pyramidal coordination by one Mg and two Ca. Calcium is 7- and 8-coordinate forming CaFO6, CaF2O2(H2O)4, CaFO3(H2O)4 and CaO2(H2O)6 coordination polyhedra. The crystal structure is built up from MgCa3F2[UO2(CO3)3]ṡ8H2O layers parallel to (001) which are linked by Ca[UO2(CO3)3]ṡ5H2O moieties into a framework of the composition MgCa4F2[UO2(CO3)3]ṡ13H2O. Five additional water molecules are located in voids of the framework and show large displacement parameters. One of the water positions is partly vacant, leading to a

FTIR spectra of the solid solutions (Na0.88K0.12)VO3, (Na0.5K0.5)VO3, and Na(V0.66P0.34)O3

NASA Astrophysics Data System (ADS)

de Waal, D.; Heyns, A. M.

1992-03-01

It is known that three different solid solutions, (Na0.88K0.12)VO3, (Na0.5K0.5)VO3 and Na(V0.66P0.34)O3, form in the (Na,K)(V,P)O3 system. These compounds all have monoclinic crystal structures similar to the pure alkali metal metavanadates containing small cations, e.g. Li+ and Na+ (Space group C2/c). Metavanadates with large cations like K+, Rb+, C+s and NH+4 form orthorhombic crystals, space group Pbcm. All those are structurally related to the silicate pyroxenes. Na(V0.66P0.34)O3 and (Na0.88K0.12)VO3 have the same modified diopside structure as (alpha) - NaVO3 while (Na0.5K0.5)VO3 adopts the true diopside structure. The infrared spectra of the three solid solutions are reported here in comparison with those of (alpha) -NaVO3 and KVO3. The results are also correlated with those obtained in two independent high pressure Raman studies of NH4VO3 and RbVO3 as the introduction of a larger cation like K+ should increase the pressure in the structure.

Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

PubMed Central

Abdessameud, S.; Mezbahul-Islam, M.; Medraj, M.

2014-01-01

Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems. PMID:25383361

A High Pressure Post-Perovskite Phase Transition in NaMgF3--a MgSiO3 Analog Material

NASA Astrophysics Data System (ADS)

Martin, C.; Liu, H.; Crichton, W.; Parise, J. B.

2005-12-01

Since Murakami et al. (2004) identified a perovskite (pv, Pbnm) to post-perovskite (ppv, Cmcm) structural phase transition in MgSiO3, the transition has been reported to occur in many oxides at ultra-high pressures (>60 GPa). The layered ppv structure is rapidly shaping a better understanding of seismic anisotropy in the controversial D" region of the lower mantle. While the ppv unit cell may be derived from indexing of the powder pattern, the structure adopted at high pressure is experimentally ill-constrained due to compromised powder diffraction statistics typically obtained from small sample volumes at extreme conditions in the diamond anvil cell. NaMgF3, a structural analog material to MgSiO3 pv, exhibits a large compressibility and presents the possibility of reducing the pv-ppv transition pressure, allowing for improved powder statistics from a larger sample volume. In accordance with our previous theoretical and experimental evidence (Liu et al., 2005; Parise et al., 2004), we have observed a phase transition in NaMgF3 during two recent independent high pressure trials utilizing monochromatic x-ray diffraction and in-situ laser heating in the diamond anvil cell at pressures as low as 30 GPa. From our analysis thus far, we have found the unit cell of the high pressure phase cannot be indexed according to pv (Pbnm) or close permutations of ppv (Cmcm) unit cells predicted for NaMgF3 or unit cells observed for ppv MgSiO3 and MgGeO3. In addition, we have precluded a breakdown to high pressure phases of NaF and MgF3 as an explanation for the observed data. Upon pressure release, we observe diffraction peaks from the high pressure phase in the absence of pv NaMgF3, suggesting the high pressure structure is quenchable to ambient conditions. The results of the work in progress will be presented at the meeting.

K(Ca)3.1 channel downregulation and impaired endothelium-derived hyperpolarization-type relaxation in pulmonary arteries from chronically hypoxic rats.

PubMed

Kroigaard, Christel; Kudryavtseva, Olga; Dalsgaard, Thomas; Wandall-Frostholm, Christine; Olesen, Søren-Peter; Simonsen, Ulf

2013-04-01

Calcium-activated potassium channels of small (K(Ca)2, SK) and intermediate (K(Ca)3.1, IK) conductance are involved in endothelium-dependent relaxation of pulmonary arteries. We hypothesized that the function and expression of K(Ca)2 and K(Ca)3.1 increase as a compensatory mechanism to counteract hypoxia-induced pulmonary hypertension in rats. For functional studies, pulmonary arteries were mounted in microvascular myographs for isometric tension recordings. The K(Ca) channel expression was evaluated by immunoblotting and quantitative PCR. Although ACh induced similar relaxations, the ACh-induced relaxations were abolished by the combined inhibition of nitric oxide synthase (by L-nitro-arginine, L-NOARG), cyclo-oxygenase (by indomethacin) and soluble guanylate cyclase (by ODQ) in pulmonary arteries from hypoxic rats, whereas 20 ± 6% (n = 8) maximal relaxation in response to ACh persisted in arteries from normoxic rats. Inhibiting Na(+),K(+)-ATPase with ouabain or blocking K(Ca)2 and K(Ca)3.1 channels reduced the persisting ACh-induced relaxation. In the presence of L-NOARG and indomethacin, a novel K(Ca)2 and K(Ca)3.1 channel activator, NS4591, induced concentration- and endothelium-dependent relaxations, which were markedly reduced in arteries from chronically hypoxic rats compared with arteries from normoxic rats. The mRNA levels of K(Ca)2.3 and K(Ca)3.1 were unaltered, whereas K(Ca)2.3 protein expression was upregulated and K(Ca)3.1 protein expression downregulated in pulmonary arteries from rats exposed to hypoxia. In conclusion, endothelium-dependent relaxation was conserved in pulmonary arteries from chronically hypoxic rats, while endothelium-derived hyperpolarization (EDH)-type relaxation was impaired in chronically hypoxic pulmonary small arteries despite upregulation of K(Ca)2.3 channels. Since impaired EDH-type relaxation was accompanied by K(Ca)3.1 channel protein downregulation, these findings suggest that K(Ca)3.1 channels are important for the

Crystallization Behavior of the CaO-Al2O3-MgO System Studied with a Confocal Laser Scanning Microscope

NASA Astrophysics Data System (ADS)

Jung, Sung Suk; Sohn, Il

2012-12-01

The crystallization behavior of a calcium-aluminate system with various MgO content from 2.5 to 7.5 wt pct and CaO/Al2O3 ratios between 0.8 and 1.2 has been examined using a confocal laser scanning microscope (CLSM). CCT (continuous cooling transformation) and time temperature transformation (TTT) diagrams were constructed to identify the primary crystal phase of slag at different compositions and at cooling rates between 25 and 800 K/minutes. In the slag at a CaO/Al2O3 ratio of 1.0, crystallization temperature increased during isothermal and continuous cooling with higher MgO content, and the shortest incubation time was observed at 5 wt pct MgO. When MgO content was fixed to be 5 wt pct, crystallization temperature increased with lower CaO/Al2O3 ratio. According to the slag composition, cooling rates and temperature, the primary phase could be CA, or C5A3, or C3A, or C3MA2, or MgO, and the crystal morphology changes from dendrites to faceted crystals to columnar crystals in this composition range.

Dachiardite-K, (K2Ca)(Al4Si20O48) · 13H2O, a new zeolite from Eastern Rhodopes, Bulgaria

NASA Astrophysics Data System (ADS)

Chukanov, N. V.; Encheva, S.; Petrov, P.; Pekov, I. V.; Belakovskiy, D. I.; Britvin, S. N.; Aksenov, S. M.

2016-12-01

Dachiardite-K (IMA No. 2015-041), a new zeolite, is a K-dominant member of the dachiardite series with the idealized formula (K2Ca)(Al4Si20O48) · 13H2O. It occurs in the walls of opal-chalcedony veinlets cutting hydrothermally altered effusive rocks of the Zvezdel paleovolcanic complex near the village of Austa, Momchilgrad Municipality, Eastern Rhodopes, Bulgaria. Chalcedony, opal, dachiardite-Ca, dachiardite-Na, ferrierite-Mg, ferrierite-K, clinoptilolite-Ca, clinoptilolite-K, mordenite, smectite, celadonite, calcite, and barite are associated minerals. The mineral forms radiated aggregates up to 8 mm in diameter consisting of split acicular individuals. Dachiardite-K is white to colorless. Perfect cleavage is observed on (100). D meas = 2.18(2), D calc = 2.169 g/cm3. The IR spectrum is given. Dachiardite-K is biaxial (+), α = 1.477 (calc), β = 1.478(2), γ = 1.481(2), 2 V meas = 65(10)°. The chemical composition (electron microprobe, mean of six point analyses, H2O determined by gravimetric method) is as follows, wt %: 4.51 K2O, 3.27 CaO, 0.41 BaO, 10.36 A12O3, 67.90 SiO2, 13.2 H2O, total is 99.65. The empirical formula is H26.23K1.71Ca1.04Ba0.05Al3.64Si20.24O61. The strongest reflections in the powder X-ray diffraction pattern [ d, Å (I, %) (hkl)] are: 9.76 (24) (001), 8.85 (58) (200), 4.870 (59) (002), 3.807 (16) (202), 3.768 (20) (112, 020), 3.457 (100) (220), 2.966 (17) (602). Dachiardite-K is monoclinic, space gr. C2/m, Cm or C2; the unit cell parameters refined from the powder X-ray diffraction data are: a = 18.670(8), b = 7.511(3), c = 10.231(4) Å, β = 107.79(3)°, V= 1366(1) Å3, Z = 1. The type specimen has been deposited in the Earth and Man National Museum, Sofia, Bulgaria, with the registration number 23927.

Multiphase oxidation of SO2 by NO2 on CaCO3 particles

NASA Astrophysics Data System (ADS)

Zhao, Defeng; Song, Xiaojuan; Zhu, Tong; Zhang, Zefeng; Liu, Yingjun; Shang, Jing

2018-02-01

Heterogeneous/multiphase oxidation of SO2 by NO2 on solid or aqueous particles is thought to be a potentially important source of sulfate in the atmosphere, for example, during heavily polluted episodes (haze), but the reaction mechanism and rate are uncertain. In this study, in order to assess the importance of the direct oxidation of SO2 by NO2 we investigated the heterogeneous/multiphase reaction of SO2 with NO2 on individual CaCO3 particles in N2 using Micro-Raman spectroscopy. In the SO2 / NO2 / H2O / N2 gas mixture, the CaCO3 solid particle was first converted to the Ca(NO3)2 droplet by the reaction with NO2 and the deliquescence of Ca(NO3)2, and then NO2 oxidized SO2 in the Ca(NO3)2 droplet forming CaSO4, which appeared as needle-shaped crystals. Sulfate was mainly formed after the complete conversion of CaCO3 to Ca(NO3)2, that is, during the multiphase oxidation of SO2 by NO2. The precipitation of CaSO4 from the droplet solution promoted sulfate formation. The reactive uptake coefficient of SO2 for sulfate formation is on the order of 10-8, and RH enhanced the uptake coefficient. We estimate that the direct multiphase oxidation of SO2 by NO2 is not an important source of sulfate in the ambient atmosphere compared with the SO2 oxidation by OH in the gas phase and is not as important as other aqueous-phase pathways, such as the reactions of SO2 with H2O2, O3, and O2, with or without transition metals.

Phase Transformation and Creep of Mg-Al-Ca Based Die-Cast Alloys

NASA Astrophysics Data System (ADS)

Suzuki, Akane; Saddock, Nicholas D.; Jones, J. Wayne; Pollock, Tresa M.

The microstructure and microstructural stability of die-cast AC53 (Mg-5Al-3Ca) and AXJ530 (Mg-5Al-3Ca-0.15Sr) have been investigated in detail by transmission electron microscopy (TEM). Both alloys have an as-cast microstructure of α-Mg with (Mg, Al)2Ca (dihexagonal C36) eutectic at grain boundaries. During aging at 573 K, the C36 phase transforms to Al2Ca (cubic Cl5) phase. These two phases have a crystallographic orientation relationship of (0001)C36//{111}C15 and [2110]C36//[011]C15, and the transformation from C36 to C15 occurs by a shear-assisted process. Despite this change in the phase constitution, the network structure of the intermetallic compound(s) surrounding α-Mg grains is fairly stable, morphologically, even after prolonged exposure at elevated temperature. In the α-Mg matrix phase, precipitation of Al2Ca was observed after aging for 360 ks at 573 K. The precipitates are disc-shaped with a habit plane of {111}C15//(0001)α. AXJ530 shows higher creep resistance than AC53. The dislocation substructure that evolved during creep deformation was investigated in both alloys, and the basal and non-basal slip of a-dislocation and other slip modes of a+c- dislocations were observed. The relationship between creep properties and microstructure is discussed.

New positive Ca2+-activated K+ channel gating modulators with selectivity for KCa3.1.

PubMed

Coleman, Nichole; Brown, Brandon M; Oliván-Viguera, Aida; Singh, Vikrant; Olmstead, Marilyn M; Valero, Marta Sofia; Köhler, Ralf; Wulff, Heike

2014-09-01

Small-conductance (KCa2) and intermediate-conductance (KCa3.1) calcium-activated K(+) channels are voltage-independent and share a common calcium/calmodulin-mediated gating mechanism. Existing positive gating modulators like EBIO, NS309, or SKA-31 activate both KCa2 and KCa3.1 channels with similar potency or, as in the case of CyPPA and NS13001, selectively activate KCa2.2 and KCa2.3 channels. We performed a structure-activity relationship (SAR) study with the aim of optimizing the benzothiazole pharmacophore of SKA-31 toward KCa3.1 selectivity. We identified SKA-111 (5-methylnaphtho[1,2-d]thiazol-2-amine), which displays 123-fold selectivity for KCa3.1 (EC50 111 ± 27 nM) over KCa2.3 (EC50 13.7 ± 6.9 μM), and SKA-121 (5-methylnaphtho[2,1-d]oxazol-2-amine), which displays 41-fold selectivity for KCa3.1 (EC50 109 nM ± 14 nM) over KCa2.3 (EC50 4.4 ± 1.6 μM). Both compounds are 200- to 400-fold selective over representative KV (KV1.3, KV2.1, KV3.1, and KV11.1), NaV (NaV1.2, NaV1.4, NaV1.5, and NaV1.7), as well as CaV1.2 channels. SKA-121 is a typical positive-gating modulator and shifts the calcium-concentration response curve of KCa3.1 to the left. In blood pressure telemetry experiments, SKA-121 (100 mg/kg i.p.) significantly lowered mean arterial blood pressure in normotensive and hypertensive wild-type but not in KCa3.1(-/-) mice. SKA-111, which was found in pharmacokinetic experiments to have a much longer half-life and to be much more brain penetrant than SKA-121, not only lowered blood pressure but also drastically reduced heart rate, presumably through cardiac and neuronal KCa2 activation when dosed at 100 mg/kg. In conclusion, with SKA-121, we generated a KCa3.1-specific positive gating modulator suitable for further exploring the therapeutical potential of KCa3.1 activation. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Dynamic redistribution of calcium sensitive potassium channels (hK(Ca)3.1) in migrating cells.

PubMed

Schwab, Albrecht; Nechyporuk-Zloy, Volodymyr; Gassner, Birgit; Schulz, Christoph; Kessler, Wolfram; Mally, Sabine; Römer, Michael; Stock, Christian

2012-02-01

Calcium-sensitive potassium channels (K(Ca)3.1) are expressed in virtually all migrating cells. Their activity is required for optimal cell migration so that their blockade leads to slowing down. K(Ca)3.1 channels must be inserted into the plasma membrane in order to elicit their physiological function. However, the plasma membrane of migrating cells is subject to rapid recycling by means of endo- and exocytosis. Here, we focussed on the endocytic internalization and the intracellular transport of the human isoform hK(Ca)3.1. A hK(Ca)3.1 channel construct with an HA-tag in the extracellularly located S3-S4 linker was transfected into migrating transformed renal epithelial MDCK-F cells. Channel internalization was visualized and quantified with immunofluorescence and a cell-based ELISA. Movement of hK(Ca)3.1 channel containing vesicles as well as migration of MDCK-F cells were monitored by means of time lapse video microscopy. hK(Ca)3.1 channels are endocytosed during migration. Most of the hK(Ca)3.1 channel containing vesicles are moving at a speed of up to 2 µm/sec in a microtubule-dependent manner towards the front of MDCK-F cells. Our experiments indicate that endocytosis of hK(Ca)3.1 channels is clathrin-dependent since they colocalize with clathrin adaptor proteins and since it is impaired when a C-terminal dileucine motif is mutated. The C-terminal dileucine motif is also important for the subcellular localization of hK(Ca)3.1 channels in migrating cells. Mutated channels are no longer concentrated at the leading edge. We therefore propose that recycling of hK(Ca)3.1 channels contributes to their characteristic subcellular distribution in migrating cells. Copyright © 2011 Wiley Periodicals, Inc.

Phase diagram of the LiNO3-NaNO3-NaCl-Sr(NO3)2 salt system

NASA Astrophysics Data System (ADS)

Rasulov, A. I.; Gasanaliev, A. M.; Mamedova, A. K.; Gamataeva, B. Yu.

2015-04-01

The phase diagram of the quaternary LiNO3-NaNO3-NaCl-Sr(NO3)2 system is studied by means of differential thermal analysis, and the compositions and crystallization temperatures of nonvariant equilibrium phases are revealed. The temperature dependence of conductivity in eutectic and peritectic salt compositions is investigated.

Electrosynthesis of Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 from Ti-Bearing Blast Furnace Slag in Molten CaCl2

NASA Astrophysics Data System (ADS)

Li, Shangshu; Zou, Xingli; Zheng, Kai; Lu, Xionggang; Chen, Chaoyi; Li, Xin; Xu, Qian; Zhou, Zhongfu

2018-04-01

Ti5Si3, Ti5Si3/TiC, and Ti5Si3/Ti3SiC2 have been electrochemically synthesized from the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors at a cell voltage of 3.8 V and 1223 K to 1273 K (950 °C to 1000 °C) in molten CaCl2. The pressed porous mixture pellets were used as the cathode, and a solid oxide oxygen-ion-conducting membrane (SOM)-based anode was used as the anode. The phase composition and morphologies of the cathodic products were systematically characterized. The final products possess a porous nodular microstructure due to the interconnection of particles. The variations of impurity elements, i.e., Ca, Mg, and Al, have been analyzed, and the result shows that Ca and Mg can be almost completely removed; however, Al cannot be easily removed from the pellet due to the formation of Ti-Al alloys during the electroreduction process. The electroreduction process has also been investigated by the layer-depended phase composition analysis of the dipped/partially reduced pellets to understand the detailed reaction process. The results indicate that the electroreduction process of the Ti-bearing blast furnace slag/TiO2 and/or C mixture precursors can be typically divided into four periods, i.e., (i) the decomposition of initial Ca(Mg,Al)(Si,Al)2O6, (ii) the reduction of Ti/Si-containing intermediate phases, (iii) the removal of impurity elements, and (iv) the formation of Ti5Si3, TiC, and Ti3SiC2. It is suggested that the SOM-based anode process has great potential to be used for the direct and facile preparation of Ti alloys and composites from cheap Ti-containing ores.

Quantitative Analysis of Ca, Mg, and K in the Roots of Angelica pubescens f. biserrata by Laser-Induced Breakdown Spectroscopy Combined with Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Wang, J.; Shi, M.; Zheng, P.; Xue, Sh.; Peng, R.

2018-03-01

Laser-induced breakdown spectroscopy has been applied for the quantitative analysis of Ca, Mg, and K in the roots of Angelica pubescens Maxim. f. biserrata Shan et Yuan used in traditional Chinese medicine. Ca II 317.993 nm, Mg I 517.268 nm, and K I 769.896 nm spectral lines have been chosen to set up calibration models for the analysis using the external standard and artificial neural network methods. The linear correlation coefficients of the predicted concentrations versus the standard concentrations of six samples determined by the artificial neural network method are 0.9896, 0.9945, and 0.9911 for Ca, Mg, and K, respectively, which are better than for the external standard method. The artificial neural network method also gives better performance comparing with the external standard method for the average and maximum relative errors, average relative standard deviations, and most maximum relative standard deviations of the predicted concentrations of Ca, Mg, and K in the six samples. Finally, it is proved that the artificial neural network method gives better performance compared to the external standard method for the quantitative analysis of Ca, Mg, and K in the roots of Angelica pubescens.

Structural characteristics of Mg-doped (1-x)(K0.5Na0.5)NbO3-xLiSbO3 lead-free ceramics as revealed by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Zhu, W. L.; Zhu, J. L.; Meng, Y.; Wang, M. S.; Zhu, B.; Zhu, X. H.; Zhu, J. G.; Xiao, D. Q.; Pezzotti, G.

2011-12-01

This paper presents a Raman spectroscopic study of compositional-change-induced structure variation and of the related mechanism of Mg doping in LiSbO3 (LS)-modified (K0.5Na0.5)NbO3 (KNN) ceramics. With increasing LS content from 0 to 0.06, a discontinuous shift towards higher wavenumbers was found for the band position of the A1g(v1) stretching mode of KNN, accompanied by a clearly nonlinear broadening of this band and a decrease in its intensity. Such morphological changes in the Raman spectrum result from two factors: (i) changes in polarizability/binding strength of the O-Nb-O vibration upon incorporation of Li ions in the KNN perovskitic structure and (ii) a polymorphic phase transition (PPT) from orthorhombic to tetragonal (O → T) phase at x > 0.04. Upon increasing the amount, w, of Mg dopant incorporated into the (1-x)KNN-xLS ceramic structure, the intensity of the Raman bands are enhanced, while the peak position and the full width at half maximum of the A1g(v1) mode was found to experience a clear dependence on both w and x. Raman characterization revealed that the mechanism of Mg doping is strongly correlated with the concentration of Li in the perovskite structure: Mg2+ ions will preferentially replace Li+ ions for low Mg doping while replace K/Na ions for higher doping of Mg. The PPT O → T was also found to be altered by the introduction of Mg and the critical value of LS concentration, xO-T, for incipient O → T transition in the KNN-xLS-wMT system was strongly dependent on Mg content, with xO → T being roughly equal to 0.04 + 2w, for the case of dilute Mg alloying.

Low pH and calcium effects on net Na+ and K+ fluxes in two catfish species from the Amazon River (Corydoras: Callichthyidae).

PubMed

Matsuo, A Y; Val, A L

2002-03-01

The present study analyzes Na+ and K+ disturbances caused by low pH in two catfish species from the Amazon River. Corydoras adolfoi inhabits ion-poor, black-stained, low pH (3.5-4.0) waters, while C. schwartzi is native to ion-rich waters at circumneutral pH. Fish were exposed to pH 3.5 Ca2+-free, and Ca2+-enriched (approximately 500 micromol/l) water to determine the protective effects of calcium. Net Na+ and K+ fluxes were measured in the water collected from the fish experimental chambers. C. adolfoi was unable to control the Na+ efflux at low pH, exhibiting Na+ loss up to -594 +/- 84 nmol g(-1) h(-1) during the first hour. After 3 and 6 h, net Na+ flux increased by 7- and 23-fold, respectively. In C. schwartzi, at pH 3.5, the initial high Na+ loss (-1,063 +/- 73 nmol g(-1) h(-1)) was gradually attenuated. A K+ loss occurred in both species, but remained relatively constant throughout exposure. High [Ca2+] affected ion losses in both species. C. adolfoi had 70% loss attenuation, indicating incapacity to control Na+ efflux. In C. schwartzi, elevated [Ca2+] completely prevented the Na+ losses caused by exposure to low pH. Rather different patterns were seen for K+ fluxes, with C. adolfoi showing no K+ disruption when exposed to low pH/high [Ca2+]. Thus, C. adolfoi loses Na+ during acid exposure, but has the ability to control K+ loss, while C. schwartzi controls diffusive Na+ loss but exhibits a slightly higher K+ loss. Ion balance was influenced by [Ca2+] at low pH in C. schwartzi but not in C. adolfoi.

Enhanced photoluminescence and thermal stability of divalent ions (Zn2+, Mg2+) assisted CaTiO3:Eu3+ perovskite phosphors for lighting applications

NASA Astrophysics Data System (ADS)

Singh, Dhananjay Kumar; Manam, J.

2018-03-01

Current study proposes the improved red emission of Zn2+ and Mg2+ ions incorporated CaTiO3:Eu3+ phosphors synthesized via the well-known solid-state reaction method. Under the 397 nm UV excitation, the Zn2+- and Mg2+-incorporated CaTiO3:0.15Eu3+ phosphor having orthorhombic structure with space group Pbnm exhibited an intense red emission at 619 nm. This can be credited to the hypersensitive 5D0 → 7F2 transition of Eu3+ ions, which is also indicative of the fact that the Eu3+ ions populated the non-inversion symmetry sites in the CaTiO3 lattices. The optimized composition CaTiO3:0.15Eu3+, 0.20Zn2+ and CaTiO3:0.15Eu3+, 0.10Mg2+ phosphors, pronounces in a magnificent enhancement of PL intensity by 5.5 and 2.5 times, respectively, as compared to CaTiO3:0.15 Eu3+ phosphor. From the temperature-dependent emission spectra, ΔEa were enunciated to be 0.101 and 0.086 eV for CaTiO3:0.15Eu3+, 0.20Zn2+ and CaTiO3:0.15Eu3+, 0.10Mg2+ phosphors, respectively, for thermal quenching. In addition, it can be better understood as related to the adequate thermal stability of 60% even at 450 and 420 K, respectively. Furthermore, the Judd-Ofelt theory was used to study the radiative intensity parameters of Eu3+ ions in the CaTiO3 lattices. The experimental results incited the bright prospects of synthesized ceramics as a promising candidate for lighting applications.

Impact of a long-term fire retardant (Fire Trol 931) on the leaching of Ca, Mg, and K from a Mediterranean forest loamy soil.

PubMed

Michalopoulos, Charalampos; Koufopoulou, Sofia; Tzamtzis, Nikolaos; Pappa, Athina

2016-03-01

The present laboratory study was conducted in pot soil taken from forest. The leaching of calcium (Ca), magnesium (Mg), and potassium (K) (plant macronutrients) due to the application of a nitrogen phosphate-based long-term fire retardant (LTFR) (Fire Trol 931) was investigated. The concentrations of Ca(2+), Mg(2+), and K(+) were measured in the resulting leachates from pots with forest soil and pine tree alone and in combination with fire. Magnesium is a minor component of Fire Trol 931. The leaching of Ca(2+), Mg(2+), and K(+) from treated soils with the retardant pots was significantly greater than that from control pots. The leaching of Mg(2+) was found to be of small percentage of the initially applied Mg quantities. Fire Trol 931 application resulted in the leaching of Ca(2+), Mg(2+), and K(+) from a typical Mediterranean forest soil in pots, following the application of simulated annual precipitation probably due to ammonium (one of the major retardant components) soil deposition that mobilizes base cations from the soil. It seems that LTFR application may result in chemical leaching from the soil to the drainage water.

Synthetic water soluble di-/tritopic molecular receptors exhibiting Ca2+/Mg2+ exchange.

PubMed

Lavie-Cambot, Aurélie; Tron, Arnaud; Ducrot, Aurélien; Castet, Frédéric; Kauffmann, Brice; Beauté, Louis; Allouchi, Hassan; Pozzo, Jean-Luc; Bonnet, Célia S; McClenaghan, Nathan D

2017-05-23

Structural integration of two synthetic water soluble receptors for Ca 2+ and Mg 2+ , namely 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and o-aminophenol-N,N,O-triacetic acid (APTRA), respectively, gave novel di- and tritopic ionophores (1 and 2). As Mg 2+ and Ca 2+ cannot be simultaneously complexed by the receptors, allosteric control of complexation results. Potentiometric measurements established stepwise protonation constants and showed high affinity for Ca 2+ (log K = 6.08 and 8.70 for 1 and 2, respectively) and an excellent selectivity over Mg 2+ (log K = 3.70 and 5.60 for 1 and 2, respectively), which is compatible with magnesium-calcium ion exchange. While ion-exchange of a single Mg 2+ for a single Ca 2+ is possible in both 1 and 2, the simultaneous binding of two Mg 2+ by 2 appears prohibitive for replacement of these two ions by a single Ca 2+ . Ion-binding and exchange was further rationalized by DFT calculations.

[Alleviation effects of melatonin and Ca2+ on melon seedlings under salt stress].

PubMed

Gao, Qing Hai; Guo, Yuan Yuan; Wu, Yan; Jia, Shuang Shuang

2017-06-18

To assess the role of exogenous melatonin (MT) and Ca 2+ in melon under salt stress, the content of mineral elements (Cl - , Na + , K + , Mg 2+ , Ca 2+ ), the values of Na + /K + , Na + /Ca 2+ , Na + /Mg 2+ , the activity of H + -ATP, the accumulation of osmotic substances and membrane lipid peroxidation in melon under salt stress were investigated in the environmental conditions (day/night 25/18 ℃) controlled by artificial climate chamber. The results showed that salt stress significantly inhibited growth of the melon seedlings with the increased contents of Cl - and Na + in roots and lea-ves, and the decreased contents of K + , Mg 2+ and Ca 2+ , compared with the control. Under salt stress, exogenous application of MT or Ca 2+ remarkably reduced the contents of Cl - and Na + in roots and leaves, increased the contents of K + , Mg 2+ and Ca 2+ , and decreased values of Na + /K + , Na + /Ca 2+ and Na + /Mg 2+ . Additionally, exogenous melatonin or Ca 2+ increased H + -ATP activity and osmotic adjustments, and further alleviated cell membrane injuries imposed by salt stress, displaying lower MDA content and relative conductivity. Collectively, this work suggested that single or combined applications of exogenous MT and Ca 2+ effectively reduced the content of Cl - and Na + , improved ion balance by enhancing H + -ATP activity, and increased the content of osmotic adjustment substances for ameliorating membrane lipid peroxidation, thereby enhancing plant adaptation to salt stress, especially combined applications of exogenous MT and Ca 2+ . Our results further showed that the combined application of exogenous MT and Ca 2+ resulted in a synergistic effect on increasing salt tolerance in melon seedlings.

Gastrointestinal transport of Ca2+ and Mg2+ during the digestion of a single meal in the freshwater rainbow trout.

PubMed

Bucking, Carol; Wood, Chris M

2007-04-01

A diet containing an inert marker (ballotini beads, quantified by X-radiography) was used to quantify the transport of two essential minerals, Ca(2+) and Mg(2+) from the diet during the digestion and absorption of a single meal of commercial trout food (3% ration). Initially, net uptake of Ca(2+) was observed in the stomach followed by subsequent Ca(2+) fluxes along the intestine which were variable, but for the most part secretory. This indicated a net secretion of Ca(2+) along the intestinal tract resulting in a net assimilation of dietary Ca(2+) of 28%. Similar handling of Ca(2+) and Mg(2+) was observed along the gastrointestinal tract (GI), although net assimilation differed substantially between the cations, with Mg(2+) assimilation being close to 60%, mostly a result of greater uptake by the stomach. The stomach displayed the highest net uptake rates for both cations (1.5 and 1.3 mmol kg(-1) fish body mass for Ca(2+) and Mg(2+), respectively), occurring within 2 h following ingestion of the meal. Substantial secretions of both Ca(2+) and Mg(2+) were observed in the anterior intestine, which were attributed to bile and other intestinal secretions, while fluxes in the mid and posterior intestine were small and variable. The overall patterns of Ca(2+) and Mg(2+) handling in the GI tract were similar to those observed for Na(+) and K(+) (but not Cl(-)) in a previous study. Overall, these results emphasize the importance of dietary electrolytes in ionoregulatory homeostasis.

Oxidative stress and Na,K-ATPase activity differential regulation in brainstem and forebrain of Wistar Audiogenic rats may lead to increased seizure susceptibility.

PubMed

Parreira, Gabriela Machado; Resende, Maria Daniela Aparecida; Garcia, Israel José Pereira; Sartori, Daniela Bueno; Umeoka, Eduardo Henrique de Lima; Godoy, Lívea Dornela; Garcia-Cairasco, Norberto; Barbosa, Leandro Augusto; Santos, Hérica de Lima; Tilelli, Cristiane Queixa

2018-01-15

The Wistar Audiogenic Rat (WAR) is a well-characterized seizure-prone, inbred rodent strain that, when acutely stimulated with high-intensity sounds, develops brainstem-dependent tonic-clonic seizures that can evolve to limbic-like, myoclonic (forebrain) seizures when the acoustic stimuli are presented chronically (audiogenic kindling). In order to investigate possible mechanisms underlying WAR susceptibility to seizures, we evaluated Na,K-ATPase activity, Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and oxidative stress markers in whole forebrain and whole brainstem samples of naïve WAR, as compared to samples from control Wistar rats. We also evaluated the expression levels of α1 and α3 isoforms of Na,K-ATPase in forebrain samples. We observed increased Na,K-ATPase activity in forebrain samples and increased oxidative stress markers (lipid peroxidation, glutathione peroxidase and superoxide dismutase) in brainstem samples of WAR. The Ca-ATPase activity, Mg-ATPase activity, lipid membrane composition and expression levels of α1 and α3 isoforms of Na,K-ATPase were unaltered. In view of previous data showing that the membrane potentials from naïve WAR's neurons are less negative than that from neurons from Wistar rats, we suggest that Na,K-ATPase increased activity might be involved in a compensatory mechanism necessary to maintain WAR's brains normal activity. Additionally, ongoing oxidative stress in the brainstem could bring Na,K-ATPase activity back to normal levels, which may explain why WAR's present increased susceptibility to seizures triggered by high-intensity sound stimulation. Copyright © 2017 Elsevier B.V. All rights reserved.

Model study of ATP and ADP buffering, transport of Ca(2+) and Mg(2+), and regulation of ion pumps in ventricular myocyte

NASA Technical Reports Server (NTRS)

Michailova, A.; McCulloch, A.

2001-01-01

We extended the model of the ventricular myocyte by Winslow et al. (Circ. Res 1999, 84:571-586) by incorporating equations for Ca(2+) and Mg(2+) buffering and transport by ATP and ADP and equations for MgATP regulation of ion transporters (Na(+)-K(+) pump, sarcolemmal and sarcoplasmic Ca(2+) pumps). The results indicate that, under normal conditions, Ca(2+) binding by low-affinity ATP and diffusion of CaATP may affect the amplitude and time course of intracellular Ca(2+) signals. The model also suggests that a fall in ATP/ADP ratio significantly reduces sarcoplasmic Ca(2+) content, increases diastolic Ca(2+), lowers systolic Ca(2+), increases Ca(2+) influx through L-type channels, and decreases the efficiency of the Na(+)/Ca(2+) exchanger in extruding Ca(2+) during periodic voltage-clamp stimulation. The analysis suggests that the most important reason for these changes during metabolic inhibition is the down-regulation of the sarcoplasmic Ca(2+)-ATPase pump by reduced diastolic MgATP levels. High Ca(2+) concentrations developed near the membrane might have a greater influence on Mg(2+), ATP, and ADP concentrations than that of the lower Ca(2+) concentrations in the bulk myoplasm. The model predictions are in general agreement with experimental observations measured under normal and pathological conditions.

Fluoride gastrointestinal absorption from Na2FPO3/CaCO3- and NaF/SiO2-based toothpastes.

PubMed

Falcão, A; Tenuta, L M A; Cury, J A

2013-01-01

Depending on toothpaste formulation, part of the fluoride is insoluble and would not be totally absorbable in the gastrointestinal tract, thus changing dental fluorosis risk estimation. This hypothesis was tested with formulations with either all fluoride in a soluble form (NaF/SiO2-based toothpaste, 1,100 µg F/g as labeled, 1,129.7 ± 49.4 µg F/g soluble fluoride as analyzed) or with around 20% of insoluble fluoride (Na2FPO3/CaCO3-based toothpaste, 1,450 µg F/g as labeled, 1,122.4 ± 76.4 µg F/g soluble fluoride as analyzed). Toothpastes were evaluated either fresh or after accelerated aging, which increased insoluble fluoride to 40% in the Na2FPO3/CaCO3-based toothpaste. In a blind, crossover clinical trial conducted in five legs, 20 adult volunteers ingested 49.5 µg of total fluoride/kg body weight from each formulation or purified water (control). Whole saliva and urine were collected as bioavailability indicators, and pharmacokinetics parameters calculated showed significantly (p < 0.05) lower fluoride bioavailability for Na2FPO3/CaCO3 toothpaste, which was reduced further after aging. A significant correlation between the amount of soluble fluoride ingested, but not total fluoride, and fluoride bioavailability was found (r = 0.57, p < 0.0001). The findings suggest that the estimated fluorosis risk as a result of ingestion of Na2FPO3/CaCO3-based toothpastes should be calculated based on the toothpaste's soluble rather than total fluoride concentration. Copyright © 2012 S. Karger AG, Basel.

Mechanochemical synthesis of MgF2 - MF2 composite systems (M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Scholz, G.; Breitfeld, S.; Krahl, T.; Düvel, A.; Heitjans, P.; Kemnitz, E.

2015-12-01

The capability of mechanochemical synthesis for the formation of MgF2-MF2 (M: Ca, Sr, Ba) composites, solid solutions or well-defined compounds was tested applying a fluorination of different fluorine-free metal sources with NH4F directly at milling. No evidence was found for a substitution of Mg2+ with Ca2+ (Sr2+, Ba2+) ions, or vice versa, in rutile or fluorite structure. However, an equimolar ratio of Mg2+ to the second cation allows the mechanochemical synthesis of tetrafluoromagnesates, MMgF4, which is more and more hampered the smaller the radius of the cation M2+ is. BaMgF4 is formed even phase pure from the acetates, SrMgF4 can only be observed in a mixture accompanied by the binary fluorides. In addition, 19F MAS NMR spectra along with calculations of 19F isotropic chemical shift values according to the superposition model point to the formation of a metastable phase of CaMgF4, which disappears at thermal treatment and decomposes into the binary fluorides CaF2 and MgF2.

Experimental and theoretical insight into the cooperativity effect in composite wax powder and ternary complex of coronene with CH4 and Mn+ (Mn+ = Li+, Na+, K+, Be2+, Mg2+ or Ca2+)

NASA Astrophysics Data System (ADS)

Jiang, Le-tao; Bai, Pei-kang; Wang, Jian-hong; Liu, Bin; Li, Yu-xin

2018-01-01

The experimental infrared (IR) spectrum of composite wax powder was investigated. The frequency shifts of the C=C anti-symmetrical stretching mode were observed and the experimental cooperativity effect involving Na+...π interaction was suggested. In order to further reveal the nature of cooperativity effect, the interaction energies in Mn+...coronene...CH4 (Mn+ = Li+, Na+, K+, Be2+, Mg2+ or Ca2+) as the model systems of composite wax powder were calculated by using the B3LYP, M06-2X and MP2 methods with 6-311++G** basis set. The results show that the Mn+...π interactions were strengthened upon the formation of ternary complexes. Although the changes of absolute values of the interactions between CH4 and coronene were not obvious, the relative values were considerably significant upon the formation of ternary complexes. The cooperativity effect was perhaps the reason for the formation of notable advantage of composite wax powder upon the introduction of surfactant with cation into wax powder. Reduced density gradient and atoms-in-molecules analysis confirm the cooperativity effect in Mn+...coronene...CH4, and reveal the nature of the formation of the predominant advantage of composite wax powder.

Electron microprobe analyses of Ca, S, Mg and P distribution in incisors of Spacelab-3 rats

NASA Technical Reports Server (NTRS)

Rosenberg, G. D.; Simmons, D. J.

1985-01-01

The distribution of Ca, S, Mg and P was mapped within the incisors of Spacelab-3 rats using an electron microprobe. The data indicate that Flight rats maintained in orbit for 7 days have significantly higher Ca/Mg ratios in dentin due to both higher Ca and lower Mg content than in dentin of ground-based Controls. There is no statistical difference in distribution of either P or S within Fligth animals and Controls, but there is clear indication that, for P at least, the reason is the greater variability of the Control data. These results are consistent with those obtained on a previous NASA/COSMOS flight of 18.5 days duration, although they are not pronounced. The results further suggest that continuously growing rat incisors provide useful records of the effects of weightlessness on Ca metabolism.

Effect of charge compensator ions (R+ = Li+, Na+ and K+) on Sr2MgSi2O7:Dy3+ phosphors by solid-state reaction method

NASA Astrophysics Data System (ADS)

Sahu, Ishwar Prasad

2016-09-01

The Sr2MgSi2O7:Dy3+ and Sr2MgSi2O7:Dy3+, R+ (R+ = Li+, Na+ and K+) phosphors were prepared by solid-state reaction method. The crystal structures of sintered phosphors were an akermanite-type structure which belongs to the tetragonal crystallography. The prepared phosphors were excited at 350 nm, and their corresponding emission spectrum were recorded at blue (482 nm) and yellow (575 nm) region due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively, of Dy3+ ions. Commission Internationale de L'Eclairage coordinates have been calculated for each sample and its value exhibited that overall emission is near white light. The possible mechanisms of discussed white light emitting phosphors were also investigated. In order to investigate the suitability of the samples as white color light sources for industrial uses, color purity, correlated color temperature (CCT) and color rendering index (CRI) were calculated. Values of color purity, CCT and CRI were found well within the defined acceptable range. With incorporating (R+ = Li+, Na+ and K+) as charge compensator ions, the emission intensity of Sr2MgSi2O7:Dy3+ can be obviously enhanced. The results indicate that prepared phosphors may be a potential application in display devices.

Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+.

PubMed

Michailova, Anushka; Saucerman, Jeffrey; Belik, Mary Ellen; McCulloch, Andrew D

2005-03-01

Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.

Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+

NASA Technical Reports Server (NTRS)

Michailova, Anushka; Saucerman, Jeffrey; Belik, Mary Ellen; McCulloch, Andrew D.

2005-01-01

Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.

An improvement to the ligand optimisation method (LOM) for measuring the apparent dissociation constant and ligand purity in Ca2+ and Mg2+ buffer solutions.

PubMed

McGuigan, John A S; Kay, James W; Elder, Hugh Y

2014-01-01

In Ca(2+)/Mg(2+) buffers the calculated ionised concentrations ([X(2+)]) can vary by up to a factor of seven. Since there are no defined standards it is impossible to check calculated [X(2+)], making measurement essential. The ligand optimisation method (LOM) is an accurate method to measure [X(2+)] in Ca(2+)/Mg(2+) buffers; independent estimation of ligand purity extends the method to pK(/) < 4. To simplify calculation, Excel programs ALE and AEC were compiled for LOM and its extension. This paper demonstrates that the slope of the electrode in the pX range 2.000-3.301 deviates from Nernstian behaviour as it depends on the value of the lumped interference, Σ. ALE was modified to include this effect; this modified program SALE, and the programs ALE and AEC were used on simulated data for Ca(2+)-EGTA and Mg(2+)-ATP buffers, to calculate electrode and buffer characteristics as a function of Σ. Ca(2+)-electrodes have a Σ < 10(-6) mol/l and there was no difference amongst the three methods. The Σ for Mg(2+)-electrodes lies between 10(-5) and 1.5 (∗) 10(-5) mol/l and calculated [Mg(2+)] with ALE were around 3% less than the true value. SALE and AEC correctly predicted [Mg(2+)]. SALE was used to recalculate K(/) and pK(/) on measured data for Ca(2+)-EGTA and Mg(2+)-EDTA buffers. These results demonstrated that it is pK(/) that is normally distributed. Until defined standards are available, [X(2+)] in Ca(2+)/Mg(2+) buffers have to be measured. The most appropriate method is to use Ca(2+)/Mg(2) electrodes combined with the Excel programs SALE or AEC. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pyruvate kinase activity as an indicator of the level of K(+), Mg(2+), and Ca(2+) in leaves and fruits of the cucumber: the role of potassium fertilization.

PubMed

Ruiz, J M; Moreno, D A; Romero, L

1999-03-01

Little is known about the effects of K(+) fertilization on pyruvate kinase (PK) activities in cucumber (Cucumis sativus L. cv. Brunex) grown in the greenhouse on calcareous soils. Here, the effect of K rates on the concentrations of K(+), Mg(2+), and Ca(2+) and on the PK activity as a possible indicator of the levels of these cations in the leaves and fruits of cucumber plants has been studied. The treatments consisted of applications of three rates of K in the form of K(2)SO(4) (K1 = 0.075 mg mL(-)(1), K2 = 0.15 mg mL(-)(1), and K3 = 0.30 mg mL(-)(1)). In general, K(+) application in calcareous soils proved beneficial. The highest application of K(+) (K3) to the culture medium reduced, in both the leaves and fruits, the foliar concentrations of Mg(2+) and Ca(2+). These results are reflected by the lowest basal PK activities and the highest differences between the basal PK activity and activities stimulated by these two cations. The opposite effect resulted with K2, with maximal basal PK activity and minimal differences between this activity and activities stimulated by the cations, indicating a better balance in this treatment between the different cations under the experimental conditions. Finally, this trend might partly account for the highest commercial yield in plants treated with K2.

Profound regulation of Na/K pump activity by transient elevations of cytoplasmic calcium in murine cardiac myocytes

PubMed Central

Lu, Fang-Min; Deisl, Christine; Hilgemann, Donald W

2016-01-01

Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activation of Ca influx by reverse Na/Ca exchange enhances pump currents and attenuates current decay, while repeated Ca elevations suppress pump currents. Pump current enhancement reverses over 3 min, and results are similar in myocytes lacking the regulatory protein, phospholemman. Classical signaling mechanisms, including Ca-activated protein kinases and reactive oxygen, are evidently not involved. Electrogenic signals mediated by intramembrane movement of hydrophobic ions, such as hexyltriphenylphosphonium (C6TPP), increase and decrease in parallel with pump currents. Thus, transient Ca elevation and Na/K pump inactivation cause opposing sarcolemma changes that may affect diverse membrane processes. DOI: http://dx.doi.org/10.7554/eLife.19267.001 PMID:27627745

Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

NASA Astrophysics Data System (ADS)

Dolejš, David; Wagner, Thomas

2008-01-01

We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic

Investigation of thermoluminescence and kinetic parameters of CaMgB{sub 2}O{sub 5}: Dy{sup 3+} nanophosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manhas, M.; Kumar, Vinay, E-mail: vinaykumar@smvdu.ac.in; Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300

2016-05-06

In this paper, thermoluminescence (TL) properties of Dy{sup 3+} (1.5 mol %) doped CaMgB{sub 2}O{sub 5} nanophosphor after being exposed to ultraviolet (UV) radiations (λ=254nm) were investigated. In UV exposed samples, the thermoluminescence glow curve consists of a broad glow peak located at 380 K with a small shoulder at 507 K. A shift in glow peak temperature from 367 K to 380 K after the UV exposure for 80 min was observed, which clearly shows that glow peaks follow the second order kinetics. The TL intensity of the peaks increases with an increase in the exposure time of UV rays (10-180 min). The TL Anal programmore » was used to analyze the glow curve. The kinetic parameters such as activation energy (E), the frequency factor (s) and the order of kinetics (b) were calculated for CaMgB{sub 2}O{sub 5}: Dy{sup 3+} nanophosphors.« less

Na(+)/Ca(2+) exchange regulates Ca(2+)-dependent duodenal mucosal ion transport and HCO(3)(-) secretion in mice.

PubMed

Dong, Hui; Sellers, Zachary M; Smith, Anders; Chow, Jimmy Y C; Barrett, Kim E

2005-03-01

Stimulation of muscarinic receptors in duodenal mucosa raises intracellular Ca(2+), which regulates ion transport, including HCO(3)(-) secretion. However, the underlying Ca(2+) handling mechanisms are poorly understood. The aim of the present study was to determine whether Na(+)/Ca(2+) exchanger (NCX) plays a role in the regulation of duodenal mucosal ion transport and HCO(3)(-) secretion by controlling Ca(2+) homeostasis. Mouse duodenal mucosa was mounted in Ussing chambers. Net ion transport was assessed as short-circuit current (I(sc)), and HCO(3)(-) secretion was determined by pH-stat. Expression of NCX in duodenal mucosae was analyzed by Western blot, and cytosolic Ca(2+) in duodenocytes was measured by fura 2. Carbachol (100 muM) increased I(sc) in a biphasic manner: an initial transient peak within 2 min and a later sustained plateau starting at 10 min. Carbachol-induced HCO(3)(-) secretion peaked at 10 min. 2-Aminoethoxydiphenylborate (2-APB, 100 muM) or LiCl (30 mM) significantly reduced the initial peak in I(sc) by 51 or 47%, respectively, and abolished the plateau phase of I(sc) without affecting HCO(3)(-) secretion induced by carbachol. Ryanodine (100 muM), caffeine (10 mM), and nifedipine (10 muM) had no effect on either response to carbachol. In contrast, nickel (5 mM) and KB-R7943 (10-30 muM) significantly inhibited carbachol-induced increases in duodenal mucosal I(sc) and HCO(3)(-) secretion. Western blot analysis showed expression of NCX1 proteins in duodenal mucosae, and functional NCX in duodenocytes was demonstrated in Ca(2+) imaging experiments where Na(+) depletion elicited Ca(2+) entry via the reversed mode of NCX. These results indicate that NCX contributes to the regulation of Ca(2+)-dependent duodenal mucosal ion transport and HCO(3)(-) secretion that results from stimulation of muscarinic receptors.

Ca2Mg(NO3)6×12H2O-structural investigations on a new compound retrieved from chimney deposits of a combined heat and power plant

NASA Astrophysics Data System (ADS)

Kahlenberg, Volker; Tessadri, Richard; Tribus, Martina; Schmidmair, Daniela; Perfler, Lukas; Haefeker, Udo

2014-10-01

Phase analysis of incrustations retrieved from chimney deposits of a combined heat and power plant in Malchow/Germany by X-ray powder diffraction gave evidence for the existence of a previously unknown hydrous calcium magnesium nitrate. Optical investigations of the sample showed the presence of colorless platy crystals with a maximum diameter of about 250 μm embedded in a partly polycrystalline and partly glassy matrix. Aided by EDX-analysis and Raman spectroscopy, a single-crystal diffraction study performed at ambient conditions demonstrated that the material represents a phase with composition Ca2Mg(NO3)6×12H2O. Basic crystallographic data are as follows: trigonal symmetry, space group type R , a = 10.5583(5) Å, c = 19.5351(10) Å, V = 1885.97(16) Å3, Z = 3, ( R(| F|) = 0.0248). The magnesium ions are coordinated by water molecules to form distorted Mg(H2O)6-octahedra. The calcium atoms are surrounded by nine ligands. The resulting CaO9 tricapped trigonal prisms involve oxygen atoms from additional water moieties as well as from three different bidentate nitrate groups, respectively. Hydrogen bonds link one octahedron with two adjacent prisms into trimers. The trimers in turn are stacked in columns running parallel to [001]. Further hydrogen bonding between neighboring columns results in the formation of a three-dimensional network. To our best knowledge, Ca2Mg(NO3)6×12H2O represents a new structure type. However, column-like topologies with rods consisting of different types of polyhedra have been also observed in other trigonal hydrous nitrates. The structural relationships between these compounds are discussed. It is interesting to note that in previous phase equilibrium studies on the ternary system Ca(NO3)2-Mg(NO3)2-H2O no other hydrous double salt has been described. Finally, the results of the structure analysis allowed a qualitative and quantitative phase analysis of the crystalline part of the chimney deposit by the Rietveld method.

Comparative Dielectric and Ferroelectric Characteristics of Bi0.5Na0.5TiO3, CaCu3Ti4O12, and 0.5Bi0.5Na0.5TiO3-0.5CaCu3Ti4O12 Electroceramics

NASA Astrophysics Data System (ADS)

Singh, Laxman; Yadava, Shiva Sundar; Sin, Byung Cheol; Rai, Uma Shanker; Mandal, K. D.; Lee, Youngil

2016-06-01

The dielectric and ferroelectric characteristics of Bi0.5Na0.5TiO3 (BNT), CaCu3Ti4O12 (CCTO), and 0.5Bi0.5Na0.5TiO3-0.5CaCu3Ti4O12 (BNT/CCTO) ceramics are compared. X-ray diffraction patterns confirmed the formation of single phase of all the ceramics after sintering at 950°C for 15 h. Scanning electron microscopy images of the sintered ceramics reveal average grain sizes in the range from 200 nm to 2.5 μm. Energy-dispersive x-ray mapping and x-ray photoelectron spectroscopy show the presence of the elements Bi, Na, Ca, Cu, Ti, and O with uniform distribution in the ceramics. BNT/CCTO exhibits high dielectric constant ( ɛ r ˜ 6.9 × 104) compared with BNT ( ɛ r ˜ 0.13 × 104) and CCTO ( ɛ r ˜ 1.68 × 104) ceramics at 1 kHz and 503 K. The high dielectric constant of BNT/CCTO compared with BNT and CCTO is associated with a major contribution from grain boundaries, as confirmed by impedance and modulus analyses. The P- E hysteresis loop of all the ceramics measured at room temperature and 50°C exhibited typical ferroelectric nature. The remanent polarization ( P r) of BNT (1.58 μC/cm2) and CCTO (0.654 μC/cm2) ceramics are higher than that of BNT/CCTO (0.267 μC/cm2) ceramic.

Energy dispersive X-ray analyses of organelles of NaCI-treated maize root cells

NASA Astrophysics Data System (ADS)

Stelzer, Ralf

1984-04-01

NaCl sensitive plants of Zea mays cv. ADOUR were grown in nutrient solutions with or without NaCl. Frozen, hydrated root-tip tissues were investigated by means of an ETEC scanning electron microscope fitted with a KEVEX energy dispersive X-ray analyser. Morphological details of the gently etched but non-coated surface of the cross fractured specimen were easy to identify and to analyse using an electron beam with a low intensity at 10 kV. X-ray data obtained from cell compartments and organelles as nuclei, nucleoli and mitochondria within individual cells establish typical X-ray spectra. Comparisons of these spectra support the hypothesis that Na + ions are predominantly localized in vacuoles and also to a lesser extent in the cytoplasm, e.g. in small vesicles, but not in other cell organelles. Furthermore the analysed cell compartments show differences in the distribution of Mg, P, S, Cl, K and Ca effected by the addition of NaCl to the growth medium. The X-ray data are discussed in relation to the physiological meaning of a NaCl induced redistribution of elements within individual maize root cells.

Selective inhibition of K(+)-stimulation of Na,K-ATPase by bretylium.

PubMed Central

Tiku, P. E.; Nowell, P. T.

1991-01-01

1. The effects of bretylium were investigated on purified Na,K-ATPase from guinea-pig heart and on the Na/K pump in trout erythrocytes, with a view to further identifying the mechanism(s) associated with its antiarrhythmic effects. 2. Na,K-ATPase activity of the thiocyanate-dispersed enzyme was determined by the measurement of inorganic phosphate produced by ATP hydrolysis. 3. When the concentrations of each of the Na,K-ATPase activating components were varied in turn, bretylium (1-5 mmol l-1) exhibited competitive-type effects against K+ with a Ki of 1.4 mmol l-1 and noncompetitive-type effects against Na+, Mg2+ and ATP. 4. In K+ influx studies in trout erythrocytes with 86Rb+ used as the marker, the inhibition of total influx observed with bretylium (5 and 10 mmol l-1) was attributable to the bretylium cation selectively inhibiting the Na/K pump-mediated influx with the associated tosylate anion inhibiting Na/K cotransport. 5. The observed inhibition kinetics indicated that the bretylium cation (2-15 mmol l-1) competitively inhibited K+ stimulation of the Na/K pump at 6 and 1.25 mmol l-1 external K+ with a mean K1 of 2.3 mmol l-1. 6. The effects demonstrated on the functioning Na/K pump in erythrocytes confirmed the Na,K-ATPase findings, with bretylium selectively inhibiting K+ stimulation of the pump mechanism in both cases. 7. It is suggested that Na,K-ATPase inhibition may contribute to the antiarrhythmic and positive inotropic effects of bretylium with the cardiac accumulation of bretylium also possibly being a further important factor. PMID:1667290

Synthesis, energy transfer and luminescence properties of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Renping, E-mail: jxcrp@163.com; Xu, Haidong; Luo, Wenjie

Graphical abstract: PL spectra of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} and Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphors with excitation at 407 nm, and the corresponding CIE chromaticity diagram and chromaticity coordinates. - Highlights: • Novel Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is synthesized by solid-state reaction method in air. • Emission intensity of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor is enhanced ∼2 times after co-doped Bi{sup 3+} ion. • Charge compensation and energy transfer may be explained via luminescence properties. • Luminous mechanism is analyzed by energy level diagrams of WO{sub 6}{sup 6−} group, Sm{sup 3+} and Bi{sup 3+} ions.more » - Abstract: Novel Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is synthesized by solid-state reaction method in air. Host Ca{sub 2}MgWO{sub 6} with excitation 300 nm emits blue light. Ca{sub 2}MgWO{sub 6}:Bi{sup 3+} phosphor with excitation 300 and 338 nm emits yellow light. Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor with excitation 300 nm exhibits tunable emission from blue to red light by increasing Sm{sup 3+} doping concentration from 0 to 8 mol%, however, only emits red light with excitation 407 nm. Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor with excitation 300 and 338 nm emits red light. The optimal Sm{sup 3+} doping concentration is ∼5 mol% in Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor. After Bi{sup 3+} ion is co-doped, luminescence properties of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+} phosphor can be improved obviously because of Bi{sub 2}O{sub 3} as fluxing agent role and energy transfer from Bi{sup 3+} to Sm{sup 3+} ions. The possible luminous mechanism of Ca{sub 2}MgWO{sub 6}:Sm{sup 3+}, Bi{sup 3+} phosphor is analyzed and explained by simplified energy level diagrams of WO{sub 6}{sup 6−} group, Bi{sup 3+} and Sm{sup 3+} ions.« less

Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine.

PubMed

Pillans, Richard D; Good, Jonathan P; Anderson, W Gary; Hazon, Neil; Franklin, Craig E

2005-01-01

This study examined the osmoregulatory status of the euryhaline elasmobranch Carcharhinus leucas acclimated to freshwater (FW) and seawater (SW). Juvenile C. leucas captured in FW (3 mOsm l(-1) kg(-1)) were acclimated to SW (980-1,000 mOsm l(-1) kg(-1)) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l(-1) kg(-1). In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l(-1) kg(-1)) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na(+), Cl(-), K(+), Mg(2+), Ca(2+), urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na(+)/K(+)-ATPase activity. Na(+)/K(+)-ATPase activity in the gills and intestine was less than 1 mmol Pi mg(-1) protein h(-1) and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na(+)/K(+)-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na(+)/K(+)-ATPase activity was 5.6+/-0.8 and 9.2+/-0.6 mmol Pi mg(-1) protein h(-1), respectively. Na(+)/K(+)-ATPase activity in the kidney of FW and SW acclimated animals was 8.4+/-1.1 and 3.3+/-1.1 Pi mg(-1) protein h(-1), respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint.

The effect of Sinabung volcanic ash and rock phosphate nanoparticle on CEC (cation exchange capacity) base saturation exchange (K, Na, Ca, Mg) and base saturation at Andisol soils Ciater, West Java

NASA Astrophysics Data System (ADS)

Yuniarti, Anni; Arifin, Mahfud; Sofyan, Emma Trinurasi; Natalie, Betty; Sudirja, Rija; Dahliani, Dewi

2018-02-01

Andisol, soil orders which covers an upland area dominantly. The aim of this research is to know the effect between the ameliorant of Sinabung volcanic ashes with the ameliorant of rock phosphatenanoparticle towards CEC and base saturation exchange (K, Na, Ca, Mg) and the base saturation on Ciater's Andisols, West Java. A randomized complete block design (RCBD) factorial with two factors was used in this research. The first factor is the volcanic ash and the second factor is rock phosphate which consists of four levels each amount of 0%, 2.5%, 5%, 7.5% with three replications. The result showed that there was no interaction between volcanic ash and rock phosphate nanoparticle formed in first month and fourth month towards the improvement of CEC and saturation base exchange rate unless magnesium cation exchange increased in fourth month. There was independent effect of volcanic ash formed nanoparticles towards base saturation exchange increased for 5% dose. There was independent effect of rock phosphate formed nanoparticles towards base saturation exchange and increased for 5% dose. The dose combination of volcanic ashes 7.5% with phosphate rock, 5% increased the base saturation in the first month incubation.

Spatial and mineralogic variation of Na-Ca alteration in Laramide porphyry systems of Arizona

NASA Astrophysics Data System (ADS)

Runyon, S.; Seedorff, E.; Barton, M. D.; Mazdab, F. K.; Lecumberri-Sanchez, P.; Steele-MacInnis, M.

2017-12-01

Na-Ca alteration is characterized by the metasomatic addition of Ca ± Na and the loss of K. Minor volumes of Na-Ca alteration in Laramide porphyry systems develops from 3 to 8 km paleodepth. Mineral assemblages, mineral compositions, hydrogen isotopes, whole-rock analyses, and reconnaissance fluid inclusion characteristics have been documented for Na-Ca alteration in Laramide porphyry systems such as Tea Cup and Sierrita. Volumetrically minor Na-Ca alteration in Laramide porphyry systems documented in this study commonly takes the form of one of three mineral assemblages: albite-epidote-chlorite, Na-plagioclase-actinolite ± epidote, and garnet- or diopside-stable Na-plagioclase-actinolite ± epidote. These different Na-Ca mineral assemblages have broad spatial relationships, from shallow albite-chlorite-epidote to deeper Na-plagioclase-actinolite within a given district. Hydrogen isotope data on Na-Ca alteration minerals shows consistently distinct δD compositions of Na-Ca alteration minerals compared to igneous minerals in a given district. Further, calculated hydrogen isotope composition of fluids in equilibrium with Na-Ca alteration minerals are consistently enriched in δD compared to magmatic-hydrothermal fluids. Whole-rock analyses show consistent losses of K and variable addition of Na and Ca across different Na-Ca alteration assemblages. Na-Ca alteration has been well documented associated with the Jurassic arc. Previous studies demonstrated through mass balance, timing and spatial relationships, isotopic, and fluid inclusion studies that Na-Ca alteration associated with the Jurassic arc likely formed from the circulation of external, highly saline, non-magmatic fluids (e.g., Battles and Barton, 1995; Dilles et al., 1995). Na-Ca alteration documented in Laramide systems is generally similar to Na-Ca alteration documented along the Jurassic arc in mineral assemblages, compositions, and timing, but the volume of Na-Ca alteration in the Laramide systems is

The bovine TRPV3 as a pathway for the uptake of Na+, Ca2+, and NH4+

PubMed Central

Liebe, Franziska; Liebe, Hendrik

2018-01-01

Absorption of ammonia from the gastrointestinal tract results in problems that range from hepatic encephalopathy in humans to poor nitrogen efficiency of cattle with consequences for the global climate. Previous studies on epithelia and cells from the native ruminal epithelium suggest functional involvement of the bovine homologue of TRPV3 (bTRPV3) in ruminal NH4+ transport. Since the conductance of TRP channels to NH4+ has never been studied, bTRPV3 was overexpressed in HEK-293 cells and investigated using the patch-clamp technique and intracellular calcium imaging. Control cells contained the empty construct. Divalent cations blocked the conductance for monovalent cations in both cell types, with effects higher in cells expressing bTRPV3. In bTRPV3 cells, but not in controls, menthol, thymol, carvacrol, or 2-APB stimulated whole cell currents mediated by Na+, Cs+, NH4+, and K+, with a rise in intracellular Ca2+ observed in response to menthol. While only 25% of control patches showed single-channel events (with a conductance of 40.8 ± 11.9 pS for NH4+ and 25.0 ± 5.8 pS for Na+), 90% of bTRPV3 patches showed much larger conductances of 127.8 ± 4.2 pS for Na+, 240.1 ± 3.6 pS for NH4+, 34.0 ± 1.7 pS for Ca2+, and ~ 36 pS for NMDG+. Open probability, but not conductance, rose with time after patch excision. In conjunction with previous research, we suggest that bTRPV3 channels may play a role in the transport of Na+, K+, Ca2+ and NH4+ across the rumen with possible repercussions for understanding the function of TRPV3 in other epithelia. PMID:29494673

The bovine TRPV3 as a pathway for the uptake of Na+, Ca2+, and NH4.

PubMed

Schrapers, Katharina T; Sponder, Gerhard; Liebe, Franziska; Liebe, Hendrik; Stumpff, Friederike

2018-01-01

Absorption of ammonia from the gastrointestinal tract results in problems that range from hepatic encephalopathy in humans to poor nitrogen efficiency of cattle with consequences for the global climate. Previous studies on epithelia and cells from the native ruminal epithelium suggest functional involvement of the bovine homologue of TRPV3 (bTRPV3) in ruminal NH4+ transport. Since the conductance of TRP channels to NH4+ has never been studied, bTRPV3 was overexpressed in HEK-293 cells and investigated using the patch-clamp technique and intracellular calcium imaging. Control cells contained the empty construct. Divalent cations blocked the conductance for monovalent cations in both cell types, with effects higher in cells expressing bTRPV3. In bTRPV3 cells, but not in controls, menthol, thymol, carvacrol, or 2-APB stimulated whole cell currents mediated by Na+, Cs+, NH4+, and K+, with a rise in intracellular Ca2+ observed in response to menthol. While only 25% of control patches showed single-channel events (with a conductance of 40.8 ± 11.9 pS for NH4+ and 25.0 ± 5.8 pS for Na+), 90% of bTRPV3 patches showed much larger conductances of 127.8 ± 4.2 pS for Na+, 240.1 ± 3.6 pS for NH4+, 34.0 ± 1.7 pS for Ca2+, and ~ 36 pS for NMDG+. Open probability, but not conductance, rose with time after patch excision. In conjunction with previous research, we suggest that bTRPV3 channels may play a role in the transport of Na+, K+, Ca2+ and NH4+ across the rumen with possible repercussions for understanding the function of TRPV3 in other epithelia.

In vitro degradation and cytotoxicity of Mg/Ca composites produced by powder metallurgy.

PubMed

Zheng, Y F; Gu, X N; Xi, Y L; Chai, D L

2010-05-01

Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg(2)Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco's modified Eagle's medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg-1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO(3), MgCO(3)x3H(2)O, HA and Mg(OH)(2) after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity (p>0.05) to L-929 cells, whereas Mg/10Ca composite extract induced approximately 40% reduced cell viability. Copyright (c) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Different thermostabilities of sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPases from rabbit and trout muscles.

PubMed

de Toledo, F G; Albuquerque, M C; Goulart, B H; Chini, E N

1995-05-01

Trout and rabbit (Ca2+ + Mg2+)-ATPases from sarcoplasmic reticulum were compared for differences in thermal inactivation and susceptibility to trypsin digestion. The trout ATPase is more heat-sensitive than the rabbit ATPase and is stabilized by Ca2+, Na+, K+ and nucleotides. Solubilization of both ATPases shows that the two ATPases have different protein-intrinsic inactivation kinetics. When digested by trypsin, the two ATPases display different cleavage patterns. The present results indicate that the trout and rabbit ATPases have dissimilarities in protein structure that may explain the differences in thermal inactivation kinetics.

Phase Equilibria in the System "FeO"-CaO-SiO2-Al2O3-MgO at Different CaO/SiO2 Ratios

NASA Astrophysics Data System (ADS)

Jang, Kyoung-oh; Ma, Xiaodong; Zhu, Jinming; Xu, Haifa; Wang, Geoff; Zhao, Baojun

2017-06-01

The "FeO"-containing slags play an important role in the operation of an ironmaking blast furnace (BF), in particular the primary slags such as the system "FeO"-CaO-SiO2-Al2O3-2 mass pct MgO with CaO/SiO2 weight ratios of 1.3, 1.5, and 1.8 saturated with metallic iron. To investigate the characteristics of such a slag system and its behavior in BF, the phase equilibria and liquidus temperatures in the slag system have been experimentally determined using the high-temperature equilibration and quenching technique followed by an electron probe X-ray microanalysis (EPMA). Isotherms between 1553 K and 1603 K (1280 °C and 1330 °C) were determined in the primary phase fields of dicalcium silicate, melilite, spinel, and monoxide [(Mg,Fe2+)O]. Pseudo-ternary phase diagrams of (CaO + SiO2)-Al2O3-"FeO" with a fixed MgO concentration at 2 mass pct and at CaO/SiO2 ratios of 1.3, 1.5, and 1.8 have been discussed, respectively, simplifying the complexity of the slag system for easy understanding and applying in BF operation. It was found that the liquidus temperatures increase in melilite and spinel primary phase fields, but decrease in dicalcium silicate and monoxide primary phase fields with increasing Al2O3/(CaO + SiO2) ratio. In addition, the liquidus temperatures decrease with increasing "FeO" concentration in dicalcium silicate and melilite primary phase fields, while showing an increasing trend in the spinel and monoxide primary phase fields. The data resulted from this study can be used to improve and optimize currently available database of thermodynamic models used in FactSage.

Synthesis, bioactivity and preliminary biocompatibility studies of glasses in the system CaO-MgO-SiO2-Na2O-P2O5-CaF2.

PubMed

Tulyaganov, D U; Agathopoulos, S; Valerio, P; Balamurugan, A; Saranti, A; Karakassides, M A; Ferreira, J M F

2011-02-01

New compositions of bioactive glasses are proposed in the CaO-MgO-SiO(2)-Na(2)O-P(2)O(5)-CaF(2) system. Mineralization tests with immersion of the investigated glasses in simulated body fluid (SBF) at 37°C showed that the glasses favour the surface formation of hydroxyapatite (HA) from the early stages of the experiments. In the case of daily renewable SBF, monetite (CaHPO(4)) formation competed with the formation of HA. The influence of structural features of the glasses on their mineralization (bioactivity) performance is discussed. Preliminary in vitro experiments with osteoblasts' cell-cultures showed that the glasses are biocompatible and there is no evidence of toxicity. Sintering and devitrification studies of glass powder compacts were also performed. Glass-ceramics with attractive properties were obtained after heat treatment of the glasses at relatively low temperatures (up to 850°C).

A possible width-luminosity correlation of the Ca II K1 and Mg II k1 features. [of stellar atmospheres

NASA Technical Reports Server (NTRS)

Ayres, T. R.; Shine, R. A.; Linsky, J. L.

1975-01-01

Existing high resolution stellar profiles of the Ca II and Mg II resonance lines suggest a possible width-luminosity correlation of the K1 minimum features. It is shown that such a correlation can be simply understood if the continuum optical depth of the stellar temperature minimum is relatively independent of surface gravity as suggested by three stars studied in detail.

Effects of Pb plus Cd mixtures on toxicity, and internal electrolyte and osmotic balance in the rainbow trout (Oncorhynchus mykiss).

PubMed

Clemow, Yvonne H; Wilkie, Michael P

2015-04-01

The physiological and toxicological effects of Cd and Pb have been thoroughly studied, but relatively little work has been done to determine how mixtures of these metals affect fishes in soft (<100 μmol L(-1)Ca(2+)) slightly acidic (pH ∼6) waters typical of many lakes in the Canadian Shield and other regions. Recently, it has been suggested that acute exposure to Cd plus Pb mixtures (3h) had greater than additive effects on both Ca(2+) and Na(+) influx, which could potentially exacerbate disturbances to ion balance and result in greater toxicity in rainbow trout (Oncorhynchus mykiss). The goal of the present study was to test this hypothesis by assessing the physiological and toxicological effects of Cd plus Pb mixtures over longer time periods (3-5 days), but at relatively low, more environmentally relevant concentrations of these metals. Accordingly, toxicity and measurements of blood acid-base regulation (PaO2, pHa), hematology (Ht, Hb, MCHC, and Protein), ionic composition (body ions and plasma Ca(2+), Na(+), Cl(-), osmolality), unidirectional Na(+) fluxes and branchial Na(+)/K(+)-ATPase activity were measured in rainbow trout exposed to Cd plus Pb mixtures. Experiments on rainbow trout, implanted with dorsal aortic catheters for repetitive blood sampling, demonstrated that exposure to Pb alone (26 nmol PbL(-1)) was less toxic than Cd alone (6 nmol CdL(-1)), which was much less toxic to the fish than a Cd plus Pb mixture (7 nmol CdL(-1) plus 45 nmol PbL(-1)), which led to greater than additive 80% mortality by 5d. Both Cd and Pb inhibited Na(+) influx over 3d exposure to the metals, which was partially offset by decreases in the diffusive efflux (outflux) of Na(+) across the gill. Despite an absence of detectable effects of Pb alone on plasma ion balance, Cd plus Pb mixtures exacerbated Cd-induced reductions in plasma Ca(2+) concentration, and resulted in pronounced reductions in plasma Na(+), Cl(-), and osmolality. No effects on Na(+)/K(+)-ATPase activity

Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

NASA Astrophysics Data System (ADS)

Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

2017-04-01

There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

Synthesis and thermoluminescence characteristics of γ-irradiated K3Ca2(SO4)3F:Eu or Ce fluoride

NASA Astrophysics Data System (ADS)

Poddar, Anuradha; Gedam, S. C.; Dhoble, S. J.

2015-05-01

New halophosphor K3Ca2(SO4)3F activated by Eu and Ce has been synthesized by a co-precipitation method and characterized according to its thermoluminescence. The formation of traps in rare earth doped K3Ca2(SO4)3F and the effects of γ-radiation dose on the glow curve are discussed. The glow curve of K3Ca2(SO4)3F:Ce shows a prominent single peak at 150°C, whereas K3Ca2(SO4)3F:Eu and K3Ca2(SO4)3F:Ce,Eu at 142°C and 192°C, respectively. A single glow peak indicates that there is only one set of trap being activated within the particular temperature range. The presented phosphors are also studied because of its fading, reusability and trapping parameters. There was just 2% fading during a period of 10 days, indicating no serious fading problem. Trapping parameters such as order of kinetics (b), activation energy (E) and frequency factor (S) were calculated by using Chen's half-width method. The observations presented in this paper are good for lamp phosphors as well as solid-state dosimeter.

Close Association of Carbonic Anhydrase (CA2a and CA15a), Na+/H+ Exchanger (Nhe3b), and Ammonia Transporter Rhcg1 in Zebrafish Ionocytes Responsible for Na+ Uptake

PubMed Central

Ito, Yusuke; Kobayashi, Sayako; Nakamura, Nobuhiro; Miyagi, Hisako; Esaki, Masahiro; Hoshijima, Kazuyuki; Hirose, Shigehisa

2013-01-01

Freshwater (FW) fishes actively absorb salt from their environment to tolerate low salinities. We previously reported that vacuolar-type H+-ATPase/mitochondrion-rich cells (H-MRCs) on the skin epithelium of zebrafish larvae (Danio rerio) are primary sites for Na+ uptake. In this study, in an attempt to clarify the mechanism for the Na+ uptake, we performed a systematic analysis of gene expression patterns of zebrafish carbonic anhydrase (CA) isoforms and found that, of 12 CA isoforms, CA2a and CA15a are highly expressed in H-MRCs at larval stages. The ca2a and ca15a mRNA expression were salinity-dependent; they were upregulated in 0.03 mM Na+ water whereas ca15a but not ca2a was down-regulated in 70 mM Na+ water. Immunohistochemistry demonstrated cytoplasmic distribution of CA2a and apical membrane localization of CA15a. Furthermore, cell surface immunofluorescence staining revealed external surface localization of CA15a. Depletion of either CA2a or CA15a expression by Morpholino antisense oligonucleotides resulted in a significant decrease in Na+ accumulation in H-MRCs. An in situ proximity ligation assay demonstrated a very close association of CA2a, CA15a, Na+/H+ exchanger 3b (Nhe3b), and Rhcg1 ammonia transporter in H-MRC. Our findings suggest that CA2a, CA15a, and Rhcg1 play a key role in Na+uptake under FW conditions by forming a transport metabolon with Nhe3b. PMID:23565095

Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

PubMed Central

Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

1979-01-01

Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent

Relationship between Na+-dependent respiration and Na+ + K+-adenosine triphosphatase activity in the action of thyroid hormone on rat jejunal mucosa.

PubMed

Liberman, U A; Asano, Y; Lo, C S; Edelman, I S

1979-07-01

Administration of three successive doses of triiodothyronine (T3) (50 micrograms/100 g body wt), given on alternate days to thyroidectomized and euthyroid rats, stimulated oxygen consumption (QO2) and Na+ transport-dependent respiration (QO2 [5]) in the stripped jejunal mucosa, a preparation that consisted mostly of epithelial cells. The increase in QO2(t) accounted for 57% of the increment in QO2 in the transition from the hypothyroid to the euthyroid state and for 29% of the increment in the transition from the euthyroid to the hyperthyroid state. Administration of T3 to hypothyroid rats also increased the yield of epithelial cells. Injection of T3 into thyroidectomized and euthyroid rats increased the specific activity (at Vmax) of the (Na+ + K+)-dependent adenosine triphosphatase (NaK-ATPase) in jejunal crude membrane preparations. No significant change was recorded in the activity of Mg-ATPase in the same preparation. The ratio of QO2/NaK-ATPase and QO2(t)/NaK-ATPase in the various thyroid states remained constant, indicating proportionate increased in the respiratory and enzymatic indices. The effect of administration of T3 to thyroidectomized rats on the number of NaK-ATPase units (recovered in the crude membrane preparation) was estimated by: (a) Na+ + Mg++ + ATP-dependent binding of [3H]-ouabain to crude membrane fractions, and (b) the amount of the phosphorylated intermediate formed in the NaK-ATPase reaction from AT32P(gamma). Estimates were obtained of the maximal number of [3H]ouabain binding sites (Nm) and dissociation constants (Kd). Nm for [3H]ouabain and Nak-ATPase specific activity increased to about the same extent after T3 administration to thyroidectomized rats, with no change in the apparent Kd values. The amount of phosphorylated intermediate formed in jejunal crude membrane preparations also increased significantly. Thus, thyroid hormone administration may increase the number of active Na+pump sites in the plasma membrane. The apparent

The effectiveness of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) on the impurities removal of saturated salt solution

NASA Astrophysics Data System (ADS)

Pujiastuti, C.; Ngatilah, Y.; Sumada, K.; Muljani, S.

2018-01-01

Increasing the quality of salt can be done through various methods such as washing (hydro-extraction), re-crystallization, ion exchange methods and others. In the process of salt quality improvement by re-crystallization method where salt product diluted with water to form saturated solution and re-crystallized through heating process. The quality of the salt produced is influenced by the quality of the dissolved salt and the crystallization mechanism applied. In this research is proposed a concept that before the saturated salt solution is recrystallized added a chemical for removal of the impurities such as magnesium ion (Mg), calcium (Ca), potassium (K) and sulfate (SO4) is contained in a saturated salt solution. The chemical reagents that used are sodium hydroxide (NaOH) 2 N and sodium carbonate (Na2CO3) 2 N. This research aims to study effectiveness of sodium hydroxide and sodium carbonate on the impurities removal of magnesium (Mg), calcium (Ca), potassium (K) and sulfate (SO4). The results showed that the addition of sodium hydroxide solution can be decreased the impurity ions of magnesium (Mg) 95.2%, calcium ion (Ca) 45%, while the addition of sodium carbonate solution can decreased magnesium ion (Mg) 66.67% and calcium ion (Ca) 77.5%, but both types of materials are not degradable sulfate ions (SO4). The sodium hydroxide solution more effective to decrease magnesium ion than sodium carbonate solution, and the sodium carbonate solution more effective to decrease calcium ion than sodium hydroxide solution.

Improvement of Corrosion Resistance of Binary Mg-Ca Alloys Using Duplex Aluminum-Chromium Coatings

NASA Astrophysics Data System (ADS)

Daroonparvar, Mohammadreza; Yajid, Muhamad Azizi Mat; Yusof, Noordin Mohd; Bakhsheshi-Rad, Hamid Reza; Adabi, Mohsen; Hamzah, Esah; Kamali, Hussein Ali

2015-07-01

Al-AlCr was coated on Mg-Ca and Mg-Zn-Ce-La alloys using physical vapor deposition method. The surface morphology of the specimens was characterized by x-ray diffraction, scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and atomic force microscopy (AFM). The AFM results indicated that the average surface roughness of Al-AlCr coating on the Mg-Ca alloy is much lower than that of Al-AlCr coating on the Mg-Zn-Ce-La alloy. However, Al-AlCr coating on the Mg-Ca alloy presented a more compact structure with fewer pores, pinholes, and cracks than Al-AlCr coating on the Mg-Zn-Ce-La alloy. Electrochemical studies revealed that the novel coating (Al-AlCr) can remarkably reduce the corrosion rate of the Mg-Ca alloy in 3.5 wt.% NaCl solution. It was seen that the anodic current density of the Al-AlCr-coated Mg-Ca alloy was very small when compared to the Al-AlCr-coated Mg-Zn-Ce-La and uncoated alloys. Impedance modulus ( Z) of the Al-AlCr-coated samples was higher than that of the bare Mg alloys. Z of Al-AlCr-coated Mg-Ca alloy was higher than that of the Al-AlCr-coated Mg-Zn-Ce-La alloy at low frequency.

Temporal variation of aqueous-extractable Ca, Mg and K in acidified forest mountainous soils under different vegetation cover

NASA Astrophysics Data System (ADS)

Tejnecky, V.; Bradová, M.; Boruvka, L.; Vasat, R.; Nemecek, K.; Ash, C.; Sebek, O.; Rejzek, J.; Drabek, O.

2012-12-01

Acidification of forest soils is a natural degradation process which can be significantly enhanced by anthropogenic activities. Inputs of basic cations (BC - Ca, Mg and K) via precipitation, litter and soil organic matter decomposition and also via inter-soil weathering may partially mitigate the consequences of this degradation process. The aim of this study is to assess the temporal variation of aqueous-extractable Ca, Mg and K in acidified forest mountainous soils under different vegetation cover. The Jizera Mountains region (Czech Republic, northern Bohemia) was chosen as a representative soil mountainous ecosystem strongly affected by acidification. Soil and precipitation samples were collected at monthly basis from April till October/ November during the years 2009-2011. Study spots were delimited under two contrasting vegetation covers - beech and spruce monoculture. Prevailing soil types were classified as Alumic Cambisols under beech and Entic Podzols under spruce stands (according to FAO classification). Soil samples were collected from surface fermentation (F) and humified (H) organic horizons and subsurface B horizons (cambic or spodic). The collected soil samples were analyzed immediately under laboratory condition in a "fresh" state. Unsieved fresh samples were extracted by deionised water. The content of main elements (Ca, Mg, K, Al and Fe) was determined by ICP-OES. The content of major anions (SO42-, NO3-, Cl- and F-) was determined by ion-exchange chromatography (IC). Content of major anions and main elements were determined in the precipitation samples (throughfall, stemflow and bulk) as well. Besides computing the basic statistical parameters (mean, median, variance, maximum, minimum, etc.) we also employed other statistical methods such as T-test and ANOVA to assess the differences between beech and spruce vegetation spots. To carry out the temporal variability in the data we used the time series analysis and short-term forecasting by Holt

Na and K Dependence of the Na/K Pump in Cystic Fibrosis Fibroblasts

NASA Astrophysics Data System (ADS)

Reznik, Vivian M.; Schneider, Jerry A.; Mendoza, Stanley A.

1981-11-01

The Na and K dependence of the Na/K pump was measured in skin fibroblasts from patients with cystic fibrosis and age/sex-matched controls. Under basal conditions, there was no difference between control and cystic fibrosis cells in protein per cell, intracellular Na and K content, or Na/K pump activity (measured as ouabain-sensitive 86Rb uptake). There was no difference in the Na dependence of the Na/K pump between cystic fibrosis cells and control cells. In cells from patients with cystic fibrosis, the Na/K pump had a significantly lower affinity for K (Km = 1.6 mM) when compared to normals (Km = 0.9 mM). This difference was demonstrated by using two independent experimental designs.

Dolomite-II: A new high pressure polymorph of CaMg(CO3)2

NASA Astrophysics Data System (ADS)

Santillan, J.; Williams, Q.; Knittle, E.

2002-12-01

We have measured the infrared spectra and x-ray diffraction of CaMg(CO3)2-dolomite to pressures of 50 GPa at 300 K. We observe both splittings and disappearances of x-ray diffraction peaks between 15 and 20 GPa, as well as new bands in the infrared spectrum of dolomite. The onset of the changes in both the x-ray and infrared data appears to be gradual, and thus kinetically impeded: this is consistent with previous shock results. The infrared and x-ray data are consistent with dolomite adopting a calcite-III-like structure. The net volume change associated with the transition based on a calcite-III monoclinic unit cell is ~4 percent. We calculate that the high pressure phase of dolomite has a volume virtually indistinguishable from that of magnesite plus aragonite. Similarly, an assemblage of the high pressure phase of dolomite and magnesium silicate perovskite has an essentially volume to a magnesite plus calcium silicate perovskite assemblage. Our results thus indicate that high-pressure polymorphism in dolomite could stabilize CaMg(CO3)2 in the deep mantle, and thus that high-pressure polymorphs of dolomite could represent the main reservoir for carbon storage within Earth's lower mantle.

Insight into Ca-Substitution Effects on O3-Type NaNi1/3 Fe1/3 Mn1/3 O2 Cathode Materials for Sodium-Ion Batteries Application.

PubMed

Sun, Liqi; Xie, Yingying; Liao, Xiao-Zhen; Wang, Hong; Tan, Guoqiang; Chen, Zonghai; Ren, Yang; Gim, Jihyeon; Tang, Wan; He, Yu-Shi; Amine, Khalil; Ma, Zi-Feng

2018-04-18

O3-type NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NaNFM) is well investigated as a promising cathode material for sodium-ion batteries (SIBs), but the cycling stability of NaNFM still needs to be improved by using novel electrolytes or optimizing their structure with the substitution of different elements sites. To enlarge the alkali-layer distance inside the layer structure of NaNFM may benefit Na + diffusion. Herein, the effect of Ca-substitution is reported in Na sites on the structural and electrochemical properties of Na 1- x Ca x /2 NFM (x = 0, 0.05, 0.1). X-ray diffraction (XRD) patterns of the prepared Na 1- x Ca x /2 NFM samples show single α-NaFeO 2 type phase with slightly increased alkali-layer distance as Ca content increases. The cycling stabilities of Ca-substituted samples are remarkably improved. The Na 0.9 Ca 0.05 Ni 1/3 Fe 1/3 Mn 1/3 O 2 (Na 0.9 Ca 0.05 NFM) cathode delivers a capacity of 116.3 mAh g -1 with capacity retention of 92% after 200 cycles at 1C rate. In operando XRD indicates a reversible structural evolution through an O3-P3-P3-O3 sequence of Na 0.9 Ca 0.05 NFM cathode during cycling. Compared to NaNMF, the Na 0.9 Ca 0.05 NFM cathode shows a wider voltage range in pure P3 phase state during the charge/discharge process and exhibits better structure recoverability after cycling. The superior cycling stability of Na 0.9 Ca 0.05 NFM makes it a promising material for practical applications in sodium-ion batteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Na-doped La0.7Ca0.3MnO3 compounds exhibiting a large magnetocaloric effect near room temperature

NASA Astrophysics Data System (ADS)

Chi Linh, Dinh; Thi Ha, Nguyen; Huu Duc, Nguyen; Giang Nam, Le Huu; Bau, Le Viet; Manh An, Nguyen; Yu, Seong-Cho; Dang Thanh, Tran

2018-03-01

In this work, we have investigated the magnetic properties and the magnetocaloric effect of La0.7-xNaxCa0.3MnO3 compounds, which were prepared by a conventional solid-state reaction technique. The Rietveld refinement results suggested that the samples are single phase belonging to an orthorhombic structure (space group Pnma). Analyzing temperature dependence of magnetization M(T) revealed that the Curie temperature (TC) increases with increasing Na content (x). Their TC value is found to be 260-298 K for x=0.0-0.1, respectively. Base on M(T) data measured at different applied magnetic fields (H), temperature dependence of magnetic entropy change ΔSm(T) data for all the samples was calculated by using a phenomenological model. In the vicinity of TC, -ΔSm(T) curve reaches a maximum value (denoted as |ΔSmax|), which gradually increases with increasing H. Under 12 kOe, the value of |ΔSmax| is in a range of 1.47-5.19 J/kg K corresponding to the relative cooling power RCP=57.12-75.88 J/kg. Applied the universal master curve method for the magnetic entropy change, we concluded that Na-doped in La0.7-xNaxCa0.3MnO3 compounds leads to modification the nature of the magnetic phase transition from the first- to the second-order.

A thermodynamic model for the prediction of phase equilibria and speciation in the H 2O-CO 2-NaCl-CaCO 3-CaSO 4 system from 0 to 250 °C, 1 to 1000 bar with NaCl concentrations up to halite saturation

NASA Astrophysics Data System (ADS)

Li, Jun; Duan, Zhenhao

2011-08-01

A thermodynamic model is developed for the calculation of both phase and speciation equilibrium in the H 2O-CO 2-NaCl-CaCO 3-CaSO 4 system from 0 to 250 °C, and from 1 to 1000 bar with NaCl concentrations up to the saturation of halite. The vapor-liquid-solid (calcite, gypsum, anhydrite and halite) equilibrium together with the chemical equilibrium of H+,Na+,Ca, CaHCO3+,Ca(OH)+,OH-,Cl-, HCO3-,HSO4-,SO42-, CO32-,CO,CaCO and CaSO 4(aq) in the aqueous liquid phase as a function of temperature, pressure and salt concentrations can be calculated with accuracy close to the experimental results. Based on this model validated from experimental data, it can be seen that temperature, pressure and salinity all have significant effects on pH, alkalinity and speciations of aqueous solutions and on the solubility of calcite, halite, anhydrite and gypsum. The solubility of anhydrite and gypsum will decrease as temperature increases (e.g. the solubility will decrease by 90% from 360 K to 460 K). The increase of pressure may increase the solubility of sulphate minerals (e.g. gypsum solubility increases by about 20-40% from vapor pressure to 600 bar). Addition of NaCl to the solution may increase mineral solubility up to about 3 molality of NaCl, adding more NaCl beyond that may slightly decrease its solubility. Dissolved CO 2 in solution may decrease the solubility of minerals. The influence of dissolved calcite on the solubility of gypsum and anhydrite can be ignored, but dissolved gypsum or anhydrite has a big influence on the calcite solubility. Online calculation is made available on www.geochem-model.org/model.

Quantification of the functional expression of the Ca2+ -activated K+ channel KCa 3.1 on microglia from adult human neocortical tissue.

PubMed

Blomster, Linda V; Strøbaek, Dorte; Hougaard, Charlotte; Klein, Jessica; Pinborg, Lars H; Mikkelsen, Jens D; Christophersen, Palle

2016-12-01

The K Ca 3.1 channel (KCNN4) is an important modulator of microglia responses in rodents, but no information exists on functional expression on microglia from human adults. We isolated and cultured microglia (max 1% astrocytes, no neurons or oligodendrocytes) from neocortex surgically removed from epilepsy patients and employed electrophysiological whole-cell measurements and selective pharmacological tools to elucidate functional expression of K Ca 3.1. The channel expression was demonstrated as a significant increase in the voltage-independent current by NS309, a K Ca 3.1/K Ca 2 activator, followed by full inhibition upon co-application with NS6180, a highly selective K Ca 3.1 inhibitor. A major fraction (79%) of unstimulated human microglia expressed K Ca 3.1, and the difference in current between full activation and inhibition (ΔK Ca 3.1) was estimated at 292 ± 48 pA at -40 mV (n = 75), which equals at least 585 channels per cell. Serial K Ca 3.1 activation/inhibition significantly hyperpolarized/depolarized the membrane potential. The isolated human microglia were potently activated by lipopolysaccharide (LPS) shown as a prominent increase in TNF-α production. However, incubation with LPS neither changed the K Ca 3.1 current nor the fraction of K Ca 3.1 expressing cells. In contrast, the anti-inflammatory cytokine IL-4 slightly increased the K Ca 3.1 current per cell, but as the membrane area also increased, there was no significant change in channel density. A large fraction of the microglia also expressed a voltage-dependent current sensitive to the K Ca 1.1 modulators NS1619 and Paxilline and an inward-rectifying current with the characteristics of a K ir channel. The high functional expression of K Ca 3.1 in microglia from epilepsy patients accentuates the need for further investigations of its role in neuropathological processes. GLIA 2016;64:2065-2078. © 2016 Wiley Periodicals, Inc.

L alpha, L beta /of H I/, K and H /of MG II/, K and H /of CA II/ observations in a quiescent prominence with the OSO-8 LPSP instrument

NASA Astrophysics Data System (ADS)

Vial, J. C.; Martres, M. J.; Salm-Platzer, J.

1981-04-01

A sequence of images taken at different positions in the resonance lines of Ca II, Mg II, and H I was obtained over a quiescent prominence with the LPSP instrument on OSO-8. Ca II K (and H) profiles are reconstructed at different locations in the prominence with a (10 × 5) arc sec2 resolution. Significant variations of FWHM and line shifts are found: FWHM range from 0.14 Å to 0.5 Å; blue shifts reach about 14 km s-1. The ratio of K to H absolute intensities shows a large spread around the average value of 1.2. The same ratio for the Mg II lines in the whole prominence is higher (1.7), a fact already noticed at the edge of an active prominence (Vial et al., 1979). The ionization degree, as measured by the Lα/Ca K ratio, shows noticeable variations within the prominence. The La intensity is about 0.3 times the intensity measured in the quiet Sun, and the Lα/Lβ ratio is less than one half the disk value. These results indicate important variations of the thermal conditions inside the prominence.

Inhibitory effects of purified antibody against α-1 repeat (117-137) on Na(+)-Ca(2+) exchange and L-type Ca(2+) currents in rat cardiomyocytes.

PubMed

Feng, Qi-Long; Wu, Dong-Mei; Cui, Xiang-Li; Zhao, Hua-Chen; Lin, Yuan-Yuan; Zhao, Lu-Ying; Wu, Bo-Wei

2010-10-25

Considering that α-1 repeat region may be involved in the ion binding and translocation of Na(+)-Ca(2+) exchanger (NCX), it is possible that the antibodies against NCX α-1 repeat may have a crucial action on NCX activity. The aim of the present study is to investigate the effect of antibody against α-1 repeat (117-137), designated as α-1(117-137), on NCX activity. The antibody against the synthesized α-1(117-137) was prepared and affinity-purified. Whole-cell patch clamp technique was used to study the change of Na(+)-Ca(2+) exchange current (I(Na/Ca)) in adult rat cardiomyocytes. To evaluate the functional specificity of this antibody, its effects on L-type Ca(2+) current (I(Ca,L)), voltage-gated Na(+) current (I(Na)) and delayed rectifier K(+) current (I(K)) were also observed. The amino acid sequences of α-1(117-137) in NCX and residues 1 076-1 096 within L-type Ca(2+) channel were compared using EMBOSS Pairwise Alignment Algorithms. The results showed that outward and inward I(Na/Ca) were decreased by the antibody against α-1(117-137) dose-dependently in the concentration range from 10 to 160 nmol/L, with IC(50) values of 18.9 nmol/L and 22.4 nmol/L, respectively. Meanwhile, the antibody also decreased I(Ca,L) in a concentration-dependent manner with IC(50) of 22.7 nmol/L. No obvious effects of the antibody on I(Na) and I(K) were observed. Moreover, comparison of the amino acid sequences showed there was 23.8% sequence similarity between NCX α-1(117-137) and residues 1 076-1 096 within L-type Ca(2+) channel. These results suggest that antibody against α-1(117-137) is a blocking antibody to NCX and can also decrease I(Ca,L) in a concentration-dependent manner, while it does not have obvious effects on I(Na) and I(K).

The mechanism of the calorigenic action of thyroid hormone. Stimulation of Na plus + K plus-activated adenosinetriphosphatase activity.

PubMed

Ismail-Beigi, F; Edelman, I S

1971-06-01

In an earlier study, we proposed that thyroid hormone stimulation of energy utilization by the Na(+) pump mediates the calorigenic response. In this study, the effects of triiodothyronine (T(3)) on total oxygen consumption (Q(OO2)), the ouabain-sensitive oxygen consumption [Q(OO2)(t)], and NaK-ATPase in liver, kidney, and cerebrum were measured. In liver, approximately 90% of the increase in Q(OO2) produced by T(3) in either thyroidectomized or euthyroid rats was attributable to the increase in Q(OO2)(t). In kidney, the increase in Q(OO2)(t) accounted for 29% of the increase in Q(OO2) in thyroidectomized and 46% of the increase in Q(OO2) in euthyroid rats. There was no demonstrable effect of T(3) in euthyroid rats on Q(OO2) or Q(OO2)(t) of cerebral slices. The effects of T(3) on NaK-ATPase activity in homogenates were as follows: In liver +81% from euthyroid rats and +54% from hypothyroid rats. In kidney, +21% from euthyroid rats and +69% from hypothyroid rats. T(3) in euthyroid rats produced no significant changes in NaK-ATPase or Mg-ATPase activity of cerebral homogenates. Liver plasma membrane fractions showed a 69% increase in NaK-ATPase and no significant changes in either Mg-ATPase or 5'-nucleotidase activities after T(3) injection. These results indicate that thyroid hormones stimulate NaK-ATPase activity differentially. This effect may account, at least in part, for the calorigenic effects of these hormones.

The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

DOE PAGES

Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

2018-05-09

In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

The relative viscosity of NaNO 3 and NaNO 2 aqueous solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynolds, Jacob G.; Mauss, Billie M.; Daniel, Richard C.

In aqueous solution, both nitrate and nitrite are planar, monovalent, and have the same elements but different sizes and charge densities. Comparing the viscosity of NaNO 2 and NaNO 3 aqueous solutions provides an opportunity to determine the relative importance of anion size versus strength of anion interaction with water. The viscosity of aqueous NaNO 2 and NaNO 3 were measured over a temperature and concentration range relevant to nuclear waste processing. The viscosity of NaNO 2 solutions was consistently larger than NaNO 3 under all conditions, even though nitrate is larger than nitrite. This was interpreted in terms ofmore » quantum mechanical charge field molecular dynamics calculations that indicate that nitrite forms more and stronger hydrogen bonds with water per oxygen atom than nitrate. Furthermore, these hydrogen bonds inhibit rotational motion required for fluid flow, thus increasing the nitrite solution viscosity relative to that of an equivalent nitrate solution.« less

High-pressure synthesis and structural, physical properties of CaIr1-xPtxO3 and CaIr1-xRhxO3

NASA Astrophysics Data System (ADS)

Hirai, S.; Bromiley, G. D.; Klemme, S.; Irifune, T.; Ohfuji, H.; Attfield, P.; Nishiyama, N.

2010-12-01

Since the discovery of the perovskite to post-perovskite transition in MgSiO3 in a laser-heated DAC, wide attention has been focussed on the post-perovskite phase of MgSiO3. This is because the post-perovskite phase is likely to play a key role in Earth’s lowermost mantle, and because the perovskite to post-perovskite transition can explain many features of the D” seismic discontinuity. While it is meaningful to conduct further studies of MgSiO3, the post-perovskite phase of MgSiO3 cannot be quenched to ambient pressure/temperature conditions. Thus, further studies must be conducted using analogue compounds of MgSiO3 post-perovskite, which are quenchable to ambient pressure/temperature conditions. The post-perovskite phase of MgSiO3 crystallizes in a layered structure with CaIrO3-structure. Therefore, it is useful to investigate compounds with CaIrO3-structure. There are only four quenchable oxides with CaIrO3-structure reported to date: CaIrO3, CaPtO3, CaRhO3 and CaRuO3. CaIrO3 can be synthesized at ambient pressure, whilst the other three oxides can only be obtained at high pressure/temperature conditions using a multi-anvil apparatus. Further studies on these materials have revealed structural phase transitions at high P-T and a metal-insulator transition by hole doping. In the case of CaIrO3, The post-perovskite phase of CaIrO3 synthesized at 2GPa, 1373K transforms into a perovskite phase at 2GPa, 1673K. In other words, the perovskite phase can be synthesized at temperatures higher than those needed for synthesizing the post-perovskite phase. This is also the case for CaRhO3 (6GPa, 1873K) and CaRuO3 (23GPa, 1343K), while CaPtO3 remained post-perovskite at higher temperatures. We have succeeded in synthesizing solid solutions between CaIrO3, CaPtO3 and CaRhO3. We have found the systematic change in structural and physical properties of post-perovskite oxides, with composition and P-T, which broadens the future opportunity for studying post-perovskite systems

Highly efficient red-emitting BaMgBO3F:Eu3+,R+ (R: Li, Na, K, Rb) phosphor for near-UV excitation synthesized via glass precursor solid-state reaction

NASA Astrophysics Data System (ADS)

Shinozaki, Kenji; Akai, Tomoko

2017-09-01

Eu3+-doped fluoroborate crystals of BaMgBO3F were synthesized by a solid-state reaction using a glassy precursor material, and their photoluminescence (PL) was investigated. To compensate for the incorporation of Eu3+ into Ba2+ sites, samples codoped with alkali ions (Li+, Na+, K+, Rb+) were also prepared. The Eu3+-doped sample showed red PL with a quantum yield (QY) of 65% caused by near-UV excitation (λ = 393 nm), and PL intensity and QY increased with the codoping of Eu3+ and alkali ions. It was found that the Eu3+,Li+-codoped sample showed the highest PL intensity and a QY of 83%.

The intermediate-conductance Ca2+ -activated K+ channel (KCa3.1) in vascular disease.

PubMed

Tharp, D L; Bowles, D K

2009-01-01

The intermediate-conductance Ca(2+)-activated K(+) channel (K(Ca)3.1) was first described by Gardos in erythrocytes and later confirmed to play a significant role in T-cell activation and the immune response. More recently, K(Ca)3.1 has been characterized in numerous cell types which contribute to the development of vascular disease, such as T-cells, B-cells, endothelial cells, fibroblasts, macrophages, and dedifferentiated smooth muscle cells (SMCs). Physiologically, K(Ca)3.1 has been demonstrated to play a role in acetylcholine and endothelium-derived hyperpolarizing factor (EDHF) induced hyperpolarization, and thus control of blood pressure. Pathophysiologically, K(Ca)3.1 contributes to proliferation of T-cells, B-cells, fibroblasts, and vascular SMCs, as well as the migration of SMCs and macrophages and platelet coagulation. Recent studies have indicated that blockade of K(Ca)3.1, by specific blockers such as TRAM-34, could prove to be an effective treatment for vascular disease by inhibiting T-cell activation as well as preventing proliferation and migration of macrophages, endothelial cells, and SMCs. This vasculoprotective potential of K(Ca)3.1 inhibition has been confirmed in both rodent and swine models of restenosis. In this review, we will discuss the physiological and pathophysiological role of K(Ca)3.1 in cells closely associated with vascular biology, and the effect of K(Ca)3.1 blockers on the initiation and progression of vascular disease.

A new nonlinear optical silicate carbonate K2Ca[Si2O5](CO3) with a hybrid structure of kalsilite and soda-like layered fragments

NASA Astrophysics Data System (ADS)

Belokoneva, Elena L.; Stefanovich, Sergey Yu.; Volkov, Anatoly S.; Dimitrova, Olga V.

2016-10-01

Single crystals of a new silicate carbonate, K2Ca[Si2O5](CO3), have been synthesized in a multi-components hydrothermal solution with a pH value close to neutral and a high concentration of a carbonate mineralizer. The new compound has an axial structure (s.g. P6322) with unit cell parameters a = 5.04789 (15), c = 17.8668 (6) Å. Pseudosymmetry of the structure corresponds to s.g. P63/mmc which is broken only by one oxygen position. The structure consists of two layered fragments: one of the type of the mineral kalsilite (KAlSiO4) and the other of the high-temperature soda-like α-Na2CO3, Ca substituting for Na. The electro-neutral layer K2[Si2O5] (denoted K) as well as the layer Ca(CO3) (denoted S) may separately correspond to individual structures. In K2Ca[Si2O5](CO3) the S-K layers are connected together via Ca-O interactions between Ca atoms from the carbonate layer and apical O atoms from the silicate one, and also via K-O interlayer interactions. A hypothetical acentric structure, sp.gr. P-62c, is predicted on the basis of the order-disorder theory. It presents another symmetrical option for the arrangement of K-layers relative to S-layers. The K,Ca-silicate-carbonate powder produces a moderate SHG signal that is two times larger that of the α-quartz powder standard and close to other silicates with acentric structures and low electronic polarizability.

Giant dielectric constant in CaCu3Ti4O12-MgB2 composites near the percolation threshold

NASA Astrophysics Data System (ADS)

Mukherjee, Rupam; Fernandez, Lucia; Lawes, Gavin; Nadgorny, Boris

2013-03-01

We have investigated the enhancement of the dielectric constant K in CaCu3Ti4O12 (CCTO)-MgB2 composite near the percolation threshold. To optimize the dielectric properties of pure CCTO we have sintered the samples at variuos temperatures. We will present the results of the measurements of K in a broad frequency for pure CCTO for the samples sintered at 1100°C and 500°C. Commercially available MgB2 powder was mixed with different weight fractions of CCTO and the pressure of 1GPa was applied to form composite pellets. Near the percolation threshold PC, CCTO/MgB2 composite system exhibit a dramatic increase of the dielectric constant K by several orders of magnitude, compared to pure CCTO. We will also discuss the magnetic field dependence of the capacitance of CCTO composite powders.

Coupled gating of skeletal muscle ryanodine receptors is modulated by Ca2+, Mg2+, and ATP

PubMed Central

Porta, Maura; Diaz-Sylvester, Paula L.; Neumann, Jake T.; Escobar, Ariel L.; Fleischer, Sidney

2012-01-01

Coupled gating (synchronous openings and closures) of groups of skeletal muscle ryanodine receptors (RyR1), which mimics RyR1-mediated Ca2+ release underlying Ca2+ sparks, was first described by Marx et al. (Marx SO, Ondrias K, Marks AR. Science 281: 818–821, 1998). The nature of the RyR1-RyR1 interactions for coupled gating still needs to be characterized. Consequently, we defined planar lipid bilayer conditions where ∼25% of multichannel reconstitutions contain mixtures of coupled and independently gating RyR1. In ∼10% of the cases, all RyRs (2–10 channels; most frequently 3–4) gated in coupled fashion, allowing for quantification. Our results indicated that coupling required cytosolic solutions containing ATP/Mg2+ and high (50 mM) luminal Ca2+ (Calum) or Sr2+ solutions. Bursts of coupled activity (events) started and ended abruptly, with all channels activating/deactivating within ∼300 μs. Coupled RyR1 were heterogeneous, where highly active RyR1 (“drivers”) seemed open during the entire coupled event (Po = 1), while other RyR1s (“followers”) displayed abundant flickering and smaller amplitude. Drivers mean open time increased with cytosolic Ca2+ (Cacyt) or caffeine, whereas followers flicker frequency was Cacyt independent and more sensitive to inhibition by cytosolic Mg2+. Coupled events were insensitive to varying lumen-to-cytosol Ca2+ fluxes from ∼1 to 8 pA, which does not corroborate coupling of neighboring RyR1 by local Ca2+-induced Ca2+ release. However, coupling requires specific Calum sites, as it was lost when Calum was replaced by luminal Ba2+ or Mg2+. In summary, coupled events reveal complex interactions among heterogeneous RyR1, differentially modulated by cytosolic ATP/Mg2+, Cacyt, and Calum, which under cell-like ionic conditions may parallel synchronous RyR1 gating during Ca2+ sparks. PMID:22785120

Synthesis and characterization of porous CaCO3 micro/nano-particles

NASA Astrophysics Data System (ADS)

Achour, A.; Arman, A.; Islam, M.; Zavarian, A. A.; Basim Al-Zubaidi, A.; Szade, J.

2017-06-01

Porous CaCO3 particles, both micro and nano sized, were synthesized in a mixture of Ca(OH)2, hyaluronic acid (HA), glycine, NaOH and NaCl solution with supercritical carbon dioxide. The particles were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscope, Raman spectroscope (RS), X-ray photoelectron spectroscope (XPS) and scanning electron microscope techniques. All these techniques showed that the particles crystallize into only one CaCO3 structure, namely the vaterite phase. In addition, FTIR, RS and XPS indicated the presence of residual reactive species i.e. glycine, NaCl, and HA. The XRD results confirmed the presence of NaCl and γ-glycine, which is a crystalline material. Moreover, the HA seems to be mostly embedded in the bulk of the micro-particles. Such materials are promising for biomedical applications such as drug delivery.

Experimental Determination of Solubilities of Tri-calcium Di-Citrate Tetrahydrate [Ca 3[C 3H 5O(COO) 3] 2•4H 2O] Earlandite in NaCl and MgCl 2 Solutions to High Ionic Strengths and Its Pitzer Model: Applications to Nuclear Waste Isolation and Other Low Temperature Environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Yongliang; Kirkes, Leslie Dawn; Westfall, Terry

In this study, solubility measurements on tri-calcium di-citrate tetrahydrate [Ca 3[C 3H 5O(COO) 3]2•4H 2O, abbreviated as Ca 3[Citrate] 2•4H 2O] as a function of ionic strength are conducted in NaCl solutions up to I = 5.0 mol•kg –1 and in MgCl 2 solutions up to I = 7.5 mol•kg –1, at room temperature (22.5 ± 0.5°C). The solubility constant (log Kmore » $$0\\atop{sp}$$) for Ca 3[Citrate] 2•4H 2O and formation constant (logβ$$0\\atop{1}$$) for Ca[C 3H 5O(COO) 3] –Ca 3[C 3H 5O(COO) 3] 2•4H 2O (earlandite) = 3Ca 2+ + 2[C 3H 5O(COO) 3] 3– + 4H 2O (1) Ca 2+ + [C 3H 5O(COO) 3] 3– = Ca[C 3H 5O(COO) 3] – (2) are determined as –18.11 ± 0.05 and 4.97 ± 0.05, respectively, based on the Pitzer model with a set of Pitzer parameters describing the specific interactions in NaCl and M gCl 2 media.« less

In vitro corrosion behavior and in vivo biodegradation of biomedical β-Ca3(PO4)2/Mg-Zn composites.

PubMed

Yu, Kun; Chen, Liangjian; Zhao, Jun; Li, Shaojun; Dai, Yilong; Huang, Qiao; Yu, Zhiming

2012-07-01

In this study 5, 10 and 15% β-Ca(3)(PO(4))(2)/Mg-Zn composites were prepared through powder metallurgy methods, and their corrosion behavior and mechanical properties were studied in simulated body fluid (SBF) at 37°C. The 10% β-Ca(3)(PO(4))(2)/Mg-Zn composite was selected for cytocompatibility assessment and in vivo biodegradation testing. The results identified the α-Mg, MgZn and β-Ca(3)(PO(4))(2) phases in these sintered composites. The density and elastic modulus of the β-Ca(3)(PO(4))(2)/Mg-6% Zn composite match those of natural bone, and the strength is approximately double that of natural bone. The 10% β-Ca(3)(PO(4))(2)/Mg-6% Zn composites exhibit good corrosion resistance, as determined by a 30 day immersion test and electrochemical measurements in SBF at 37°C. The 10% β-Ca(3)(PO(4))(2)/Mg-6% Zn composite is safe for cellular applications, with a cytotoxicity grade of ∼0-1 against L929 cells in in vitro testing. The β-Ca(3)(PO(4))(2)/Mg-6% Zn composite also exhibits good biocompatibility with the tissue and the important visceral organs the heart, kidney and liver of experimental rabbits. The composite has a suitable degradation rate and improves the concrescence of a pre-broken bone. The corrosion products, such as Mg(OH)(2) and Ca(5)(PO(4))(6)(OH)(2), can improve the biocompatibility of the β-Ca(3)(PO(4))(2)/Mg-Zn composite. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Age-dependent changes in diastolic Ca{sup 2+} and Na{sup +} concentrations in dystrophic cardiomyopathy: Role of Ca{sup 2+} entry and IP{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mijares, Alfredo; Altamirano, Francisco; Kolster, Juan

2014-10-03

Highlights: • Age-dependent increase in [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in mdx cardiomyocytes. • Gadolinium significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. • IP{sub 3}-pathway inhibition reduced cations concentrations in dystrophic cardiomyocytes. - Abstract: Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca{sup 2+} concentration ([Ca{supmore » 2+}]{sub d}) and diastolic Na{sup +} concentration ([Na{sup +}]{sub d}) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd{sup 3+})-sensitive Ca{sup 2+} entry and inositol triphosphate (IP{sub 3}) signaling pathways in abnormal [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} were investigated. Our results showed an age-dependent increase in both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd{sup 3+} treatment significantly reduced both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages. In addition, blockade of the IP{sub 3}-pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd{sup 3+} normalized both [Ca{sup 2+}]{sub d} and [Na{sup +}]{sub d} at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca{sup 2+} and Na{sup +} overload mediated at least in part by enhanced Ca{sup 2+} entry through Gd{sup 3+} sensitive transient receptor potential channels (TRPC), and by IP{sub 3

The Na+/Ca2+, K+ exchanger NCKX4 is required for efficient cone-mediated vision.

PubMed

Vinberg, Frans; Wang, Tian; De Maria, Alicia; Zhao, Haiqing; Bassnett, Steven; Chen, Jeannie; Kefalov, Vladimir J

2017-06-26

Calcium (Ca 2+ ) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca 2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca 2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na + /Ca 2+ , K + exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca 2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival.

Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aboussatar, Mohamed; Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax; Mbarek, Aïcha

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1),more » c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F

Formation process of micro arc oxidation coatings obtained in a sodium phytate containing solution with and without CaCO3 on binary Mg-1.0Ca alloy

NASA Astrophysics Data System (ADS)

Zhang, R. F.; Zhang, Y. Q.; Zhang, S. F.; B. Qu; Guo, S. B.; Xiang, J. H.

2015-01-01

Micro arc oxidation (MAO) is an effective method to improve the corrosion resistance of magnesium alloys. In order to reveal the influence of alloying element Ca and CaCO3 electrolyte on the formation process and chemical compositions of MAO coatings on binary Mg-1.0Ca alloy, anodic coatings after different anodizing times were prepared on binary Mg-1.0Ca alloy in a base solution containing 3 g/L sodium hydroxide and 15 g/L sodium phytate with and without addition of CaCO3. The coating formation was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results show that Mg-1.0Ca alloy is composed of two phases, the Mg phase and Mg2Ca phase. After treating for 5 s, the coating began to develop and was preferentially formed on the area nearby Mg2Ca phase, which may be resulted from the intrinsic electronegative potential of the Mg phase than that of Mg2Ca phase. Anodic coatings unevenly covered the total surface after 20 s. After 80 s, the coatings were uniformly developed on Mg-1.0Ca alloy with micro pores. During MAO process, some sodium phytate molecules are hydrolyzed into inorganic phosphate. CaCO3 has minor influence on the calcium content of the obtained MAO coatings.

Sperm Na+, K+-ATPase and Ca2+-ATPase activity: A preliminary study of comparison of swim up and density gradient centrifugation methods for sperm preparation

NASA Astrophysics Data System (ADS)

Lestari, Silvia W.; Larasati, Manggiasih D.; Asmarinah, Mansur, Indra G.

2018-02-01

As one of the treatment for infertility, the success rate of Intrauterine Insemination (IUI) is still relatively low. Several sperm preparation methods, swim-up (SU) and the density-gradient centrifugation (DGC) are frequently used to select for better sperm quality which also contribute to IUI failure. Sperm selection methods mainly separate the motile from the immotile sperm, eliminating the seminal plasma. The sperm motility involves the structure and function of sperm membrane in maintaining the balance of ion transport system which is regulated by the Na+, K+-ATPase, and Ca2+-ATPase enzymes. This study aims to re-evaluate the efficiency of these methods in selecting for sperm before being used for IUI and based the evaluation on sperm Na+,K+-ATPase and Ca2+-ATPase activities. Fourteen infertile men from couples who underwent IUI were involved in this study. The SU and DGC methods were used for the sperm preparation. Semen analysis was performed based on the reference value of World Health Organization (WHO) 2010. After isolating the membrane fraction of sperms, the Na+, K+-ATPase activity was defined as the difference in the released inorganic phosphate (Pi) with and without the existence of 10 mM ouabain in the reaction, while the Ca2+-ATPase was determined as the difference in Pi contents with and without the existence of 55 µm CaCl2. The prepared sperm demonstrated a higher percentage of motile sperm compared to sperm from the whole semen. Additionally, the percentage of motile sperm of post-DGC showed higher result than the sperm from post-SU. The velocity of sperm showed similar pattern with the percentage of motile sperm, in which the velocity of prepared sperm was higher than the sperm from whole semen. Furthermore, the sperm velocity of post-DGC was higher compared to the sperm from post-SU. The Na+, K+-ATPase activity of prepared sperm was higher compared to whole semen, whereas Na+, K+-ATPase activity in the post DGC was higher than post SU. The Ca2

Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

NASA Astrophysics Data System (ADS)

Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

2017-04-01

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

Removal of Carbon Dioxide from Gas Mixtures Using Ion-Exchanged Silicoaluminophosphates

NASA Technical Reports Server (NTRS)

Hernandez-Maldonado, Arturo J (Inventor); Rivera-Ramos, Milton E (Inventor); Arevalo-Hidalgo, Ana G (Inventor)

2017-01-01

Na+-SAPO-34 sorbents were ion-exchanged with several individual metal cations for CO2 absorption at different temperatures (273-348 K) and pressures (<1 atm). In general, the overall adsorption performance of the exchanged materials increased as follows: Ce3+3+<Mg2+<Ca2+Na+mixtures, especially at low concentrations.

μ SR study of NaCaNi2F7 in zero field and applied longitudinal magnetic field

NASA Astrophysics Data System (ADS)

Cai, Yipeng; Wilson, Murray; Hallas, Alannah; Liu, Lian; Frandsen, Benjamin; Dunsiger, Sarah; Krizan, Jason; Cava, Robert; Uemura, Yasutomo; Luke, Graeme

Rich physics of abundant magnetic ground states has been realized in the A2B2X7 geometrically frustrated magnetic pyrochlores. Recently, a new spin-1 Ni2+ pyrochlore, NaCaNi2F7, was synthesized and shown to have spin freezing at 3.6 K with a frustration index of f 36 and antiferromagnetic exchange interactions [1] . This structure has chemical disorder on the A site caused by randomly distributed Ca and Na ions, which causes bond disorder around the magnetic Ni sites. We present Zero Field (ZF) and Longitudinal Field (LF) muon spin rotation (μSR) measurements on this single crystal pyrochlore. Our data shows that the Ni2+ spins start freezing around 4 K giving a static local field of 140 G. The data show no oscillations down to 75 mK which indicates no long range magnetic order. They are well described by the dynamic Gaussian Kubo-Toyabe function with a non-zero hopping rate that is not easily decoupled with an applied longitudinal field, which implies persistent spin dynamics down to 75 mK.

Emission analysis of Tb3+ -and Sm3+ -ion-doped (Li2 O/Na2 O/K2 O) and (Li2 O + Na2 O/Li2 O + K2 O/K2 O + Na2 O)-modified borosilicate glasses.

PubMed

Naveen Kumar Reddy, B; Sailaja, S; Thyagarajan, K; Jho, Young Dahl; Sudhakar Reddy, B

2018-05-01

Four series of borosilicate glasses modified by alkali oxides and doped with Tb 3+ and Sm 3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B 2 O 3 + 10SiO 2 + 5MgO + R + 0.5(Tb 2 O 3 /Sm 2 O 3 ) [where R = 10(Li 2 O /Na 2 O/K 2 O) for series A and C, and R = 5(Li 2 O + Na 2 O/Li 2 O + K 2 O/K 2 O + Na 2 O) for series B and D]. The X-ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5 D 4 → 7 F 5 (543 nm) transition of the Tb 3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm 3+ ions with the series C and D glasses showed strong reddish-orange emission at 600 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength λ exci = 404 nm ( 6 H 5/2 → 4 F 7/2 ). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb 3+ and Sm 3+ ions was studied to optimize the potential alkali-oxide-modified borosilicate glass. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of Mg2+ on the control of Ca2+ release in skeletal muscle fibres of the toad.

PubMed Central

Lamb, G D; Stephenson, D G

1991-01-01

1. The effect of myoplasmic Mg2+ on Ca2+ release was examined in mechanically skinned skeletal muscle fibres, in which the normal voltage-sensor control of Ca2+ release is preserved. The voltage sensors could be activated by depolarizing the transverse tubular (T-) system by lowering the [K+] in the bathing solution. 2. Fibres spontaneously contracted when the free [Mg2+] was decreased from 1 to 0.05 mM, with no depolarization or change of total ATP, [Ca2+] or pH (pCa 6.7, 50 microM-EGTA). After such a 'low-Mg2+ response' the sarcoplasmic reticulum (SR) was depleted of Ca2+ and neither depolarization nor caffeine (2 mM) could induce a response, unless the [Mg2+] was raised and the SR reloaded with Ca2+. Exposure to 0.05 mM-Mg2+ at low [Ca2+] (2 mM-free EGTA, pCa greater than 8.7) also induced Ca2+ release and depleted the SR. 3. The response to low [Mg2+] was unaffected by inactivation of the voltage sensors, but was completely blocked by 2 microM-Ruthenium Red indicating that it involved Ca2+ efflux through the normal Ca2+ release channels. 4. In the absence of ATP (and creatine phosphate), complete removal of Mg2+ (i.e. no added Mg2+ with 1 mM-EDTA) did not induce Ca2+ release. Depolarization in the absence of Mg2+ and ATP also did not induce Ca2+ release. 5. Depolarization in 10 mM-Mg2+ (pCa 6.7, 50 microM-EGTA, 8 mM-total ATP) did not produce any response. In the presence of 1 mM-EGTA to chelate most of the released Ca2+, depolarizations in 10 mM-Mg2+ did not noticeably deplete the SR of Ca2+, whereas a single depolarization in 1 mM-Mg2+ (and 1 mM-EGTA) resulted in marked depletion. Depolarization in the presence of D600 and 10 mM-Mg2+ produced use-dependent 'paralysis', indicating that depolarization in 10 mM-Mg2+ did indeed activate the voltage sensors. 6. Depolarization in the presence of 10 mM-Mg2+ and 25 microM-ryanodine neither interfered with the normal voltage control of Ca2+ release nor caused depletion of the Ca2+ in the SR even after returning to 1 mM-Mg

Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

NASA Astrophysics Data System (ADS)

Anawati, Asoh, Hidetaka; Ono, Sachiko

2016-04-01

Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

Two-week inhalation of budesonide increases muscle Na,K ATPase content but not endurance in response to terbutaline in men.

PubMed

Hostrup, M; Jessen, S; Onslev, J; Clausen, T; Porsbjerg, C

2017-07-01

While chronic systemic administration of glucocorticoids increases muscle Na + ,K + ATPase content, such effect is unexplored after therapeutic inhalation. We investigated the effect of therapeutic inhalation of the glucocorticoid budesonide on Na + ,K + ATPase content of skeletal muscle in men. Ten healthy trained subjects, aged 23 ± 4 years (mean ± 95% CI), participated in the study. Before and after 2 weeks of daily inhalation of budesonide (1.6 mg/day), a biopsy was taken from the vastus lateralis muscle for measurement of Na + ,K + ATPase content and blood samples were drawn for determination of plasma budesonide, cortisol, and K + . Subjects' performance during cycling to fatigue at 90% of incremental peak power output (iPPO) was measured in response to 4 mg inhaled terbutaline to maximally stimulate Na + ,K + ATPase activity. Plasma concentrations of budesonide rose to 5.0 ± 1.6 nM with the intervention, whereas no changes were observed in plasma cortisol. Muscle Na + ,K + ATPase content increased (P ≤ 0.01) by 46 ± 34 pmol/(g wet wt) (17% increase) with the intervention. Cycling performance at 90% of iPPO did not change (P = 0.21) with the intervention (203 vs 214 s) in response to terbutaline. The present observations show that therapeutic inhalation of glucocorticoids increases muscle Na + ,K + ATPase content, but does not enhance high-intensity cycling endurance in response to terbutaline. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Structural, magnetic and magnetocaloric properties of La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} manganites (0≤x≤0.2)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choura Maatar, S.; M’nassri, R.; Institut NEEL, CNRS, B.P.166, 38042 Grenoble Cedex 9

2015-05-15

In this work, we report the effect of Na doping on the structural, magnetic and magnetocaloric properties in La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} powder samples. Our polycristalline samples have been synthesized using the solid-state reaction method at high temperatures. The parent compound La{sub 0.8}Ca{sub 0.2}MnO{sub 3} crystallizes in the orthorhombic system with Pbnm space group. Na doping induces a structural transition from orthorhombic (Pbnm space group) to rhombohedral (R-3C space group) symmetry. Magnetization measurements versus temperature in a magnetic applied field of 50 mT showed that all our investigated samples display a paramagnetic-ferromagnetic transition with decreasing temperature. The Curie temperaturemore » T{sub C} increases with Na content from 240 K for x=0 to 330 K for x=0.2. A large magnetocaloric effect has been observed in all samples, the maximum entropy change, |∆S{sub M}|{sub max}, shifts to smaller values with increasing Na content, from4.56 J/kg K (x=0.05) to 2.3 J/kg K (x=0.2) under a magnetic field change ∆µ{sub 0}H of 2 T. For the same applied magnetic field of 2 T, the Relative Cooling Power (RCP) values are found to be constant around 91 J/kg. - Graphical abstract: Sodium doping induces an increase of T{sub C} from 240 K for x=0 to 330 K for x=0.2. - Highlights: • La{sub 0.8}Ca{sub 0.2−x}Na{sub x}MnO{sub 3} are synthesized using the ceramic method at high temperatures. • Na doping induces a structural transition from Pbnm to R-3C space group. • T{sub C} increases with Na content from 240 K for x=0 to 330 K for x=0.2. • RCP is constant around 91 J/kg for all compounds under 2 T.« less

Investigations on the Crystal Structure and the Stability Field of FCAM-I (Ca3MgAl6Fe10O28), an Iso-structure to SFCA-I

NASA Astrophysics Data System (ADS)

Zöll, Klaus; Manninger, Tanja; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2017-08-01

In a study on parts of the system Fe2O3-CaO-Al2O3-MgO, the previously unknown compound Ca3MgAl6Fe10O28 or FCAM-I (iso-structural with SFCA-I) has been synthesized. The two principal aims of our investigations have been (i) analysis of the stability field of the new phase as a function of T and fO2 and (ii) determination of its crystal structure. Two experimental series in air and under controlled oxygen fugacity via the hematite-magnetite buffer were conducted. Pure polycrystalline FCAM-I has been obtained at 1463.15 K (1190 °C) in air. While increasing the temperature from 1573.15 K to 1673.15 K (1300 °C to 1400 °C), the FCAM-I phase breaks down forming a variety of new compounds depending on T and fO2. Ca3MgAl6Fe10O28 has a triclinic crystal structure (space group P \\overline{1} ). Basic crystallographic data are as follows: a = 10.2980(4) Å, b = 10.4677(4) Å, c = 11.6399(4) Å, α = 94.363(3)°, β = 111.498(3)°, γ = 109.744(3)°, V = 1069.81(7) Å3, Z = 2.

Composition, response to pressure, and negative thermal expansion in M IIB IVF 6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in A IIB IVF 6; A - Ca, Mg, B - Zr, Nb

DOE PAGES

Hester, Brett R.; Hancock, Justin C.; Lapidus, Saul H.; ...

2016-12-27

CaZrF 6 has recently been shown to combine strong negative thermal expansion (NTE) over a very wide temperature range (at least 10–1000 K) with optical transparency from mid-IR into the UV range. Variable-temperature and high-pressure diffraction has been used to determine how the replacement of calcium by magnesium and zirconium by niobium(IV) modifies the phase behavior and physical properties of the compound. Similar to CaZrF 6, CaNbF 6 retains a cubic ReO 3-type structure down to 10 K and displays NTE up until at least 900 K. It undergoes a reconstructive phase transition upon compression to ~400 MPa at room temperature and pressure-induced amorphization above ~4 GPa. Prior to the first transition, it displays very strong pressure-induced softening. MgZrF 6 adopts a cubic ( Fmmore » $$\\bar{3}$$m) structure at 300 K and undergoes a symmetry-lowering phase transition involving octahedral tilts at ~100 K. Immediately above this transition, it shows modest NTE. Its’ thermal expansion increases upon heating, crossing through zero at ~500 K. Unlike CaZrF 6 and CaNbF 6, it undergoes an octahedral tilting transition upon compression (~370 MPa) prior to a reconstructive transition at ~1 GPa. Cubic MgZrF 6 displays both pressure-induced softening and stiffening upon heating. MgNbF 6 is cubic ( Fm$$\\bar{3}$$m) at room temperature, but it undergoes a symmetry-lowering octahedral tilting transition at ~280 K. It does not display NTE within the investigated temperature range (100–950 K). Furthermore the replacement of Zr(IV) by Nb(IV) leads to minor changes in phase behavior and properties, the replacement of the calcium by the smaller and more polarizing magnesium leads to large changes in both phase behavior and thermal expansion.« less

Composition, response to pressure, and negative thermal expansion in M IIB IVF 6 (M = Ca, Mg; B = Zr, Nb) [Composition, response to pressure, and negative thermal expansion in A IIB IVF 6; A - Ca, Mg, B - Zr, Nb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hester, Brett R.; Hancock, Justin C.; Lapidus, Saul H.

CaZrF 6 has recently been shown to combine strong negative thermal expansion (NTE) over a very wide temperature range (at least 10–1000 K) with optical transparency from mid-IR into the UV range. Variable-temperature and high-pressure diffraction has been used to determine how the replacement of calcium by magnesium and zirconium by niobium(IV) modifies the phase behavior and physical properties of the compound. Similar to CaZrF 6, CaNbF 6 retains a cubic ReO 3-type structure down to 10 K and displays NTE up until at least 900 K. It undergoes a reconstructive phase transition upon compression to ~400 MPa at room temperature and pressure-induced amorphization above ~4 GPa. Prior to the first transition, it displays very strong pressure-induced softening. MgZrF 6 adopts a cubic ( Fmmore » $$\\bar{3}$$m) structure at 300 K and undergoes a symmetry-lowering phase transition involving octahedral tilts at ~100 K. Immediately above this transition, it shows modest NTE. Its’ thermal expansion increases upon heating, crossing through zero at ~500 K. Unlike CaZrF 6 and CaNbF 6, it undergoes an octahedral tilting transition upon compression (~370 MPa) prior to a reconstructive transition at ~1 GPa. Cubic MgZrF 6 displays both pressure-induced softening and stiffening upon heating. MgNbF 6 is cubic ( Fm$$\\bar{3}$$m) at room temperature, but it undergoes a symmetry-lowering octahedral tilting transition at ~280 K. It does not display NTE within the investigated temperature range (100–950 K). Furthermore the replacement of Zr(IV) by Nb(IV) leads to minor changes in phase behavior and properties, the replacement of the calcium by the smaller and more polarizing magnesium leads to large changes in both phase behavior and thermal expansion.« less

Experimental Determination of the Phase Diagram of the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 System

NASA Astrophysics Data System (ADS)

Shi, Junjie; Sun, Lifeng; Zhang, Bo; Liu, Xuqiang; Qiu, Jiyu; Wang, Zhaoyun; Jiang, Maofa

2016-02-01

Ti-bearing CaO-SiO2-MgO-Al2O3-TiO2 slags are important for the smelting of vanadium-titanium bearing magnetite. In the current study, the pseudo-melting temperatures were determined by the single-hot thermocouple technique for the specified content of 5 to 25 pct TiO2 in the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 phase diagram system. The 1573 K to 1773 K (1300 °C to 1500 °C) liquidus lines were first calculated based on the pseudo-melting temperatures according to thermodynamic equations in the specific primary crystal field. The phase equilibria at 1573 K (1300 °C) were determined experimentally using the high-temperature equilibrium and quench method followed by X-ray fluorescence, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscope analysis; the liquid phase, melilite solid solution phase (C2MS2,C2AS)ss, and perovskite phase of CaO·TiO2 were found. Therefore, the phase diagram was constructed for the specified region of the CaO-SiO2-5 pctMgO-10 pctAl2O3-TiO2 system.

PPARα induced NOS1 phosphorylation via PI3K/Akt in guinea pig antral mucous cells: NO-enhancement in Ca(2+)-regulated exocytosis.

PubMed

Tanaka, Saori; Hosogi, Shigekuni; Sawabe, Yukinori; Shimamoto, Chikao; Matsumura, Hitoshi; Inui, Toshio; Marunaka, Yoshinori; Nakahari, Takashi

2016-01-01

A PPARα (peroxisome proliferation activation receptor α) agonist (GW7647) activates nitric oxide synthase 1 (NOS1) to produce NO leading to cGMP accumulation in antral mucous cells. In this study, we examined how PPARα activates NOS1. The NO production stimulated by GW7647 was suppressed by inhibitors of PI3K (wortmannin) and Akt (AKT 1/2 Kinase Inhibitor, AKT-inh), although it was also suppressed by the inhibitors of PPARα (GW6471) and NOS1 (N-PLA). GW7647 enhanced the ACh (acetylcholine)-stimulated exocytosis (Ca(2+)-regulated exocytosis) mediated via NO, which was abolished by GW6471, N-PLA, wortmannin, and AKT-inh. The Western blotting revealed that GW7647 phosphorylates NOS1 via phosphorylation of PI3K/Akt in antral mucous cells. The immunofluorescence examinations demonstrated that PPARα existing with NOS1 co-localizes with PI3K and Akt in the cytoplasm of antral mucous cells. ACh alone and AACOCF3, an analogue of arachidonic acid (AA), induced the NOS1 phosphorylation via PI3K/Akt to produce NO, which was inhibited by GW6471. Since AA is a natural ligand for PPARα, ACh stimulates PPARα probably via AA. In conclusion, PPARα activates NOS1 via PI3K/Akt phosphorylation to produce NO in antral mucous cells during ACh stimulation.

Ameloblast Modulation and Transport of Cl−, Na+, and K+ during Amelogenesis

PubMed Central

Bronckers, A.L.J.J.; Lyaruu, D.; Jalali, R.; Medina, J.F.; Zandieh-Doulabi, B.; DenBesten, P.K.

2015-01-01

Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na+K+-dependent calcium transporter NCKX4 and the Na+-dependent HPO42– (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr, Ae2a,b, and Amelx, according to quantitative x-ray electron probe microanalysis. Immunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-2b and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl− was strongly reduced; 2) K+ and Na+ accumulated (Na+ not in Amelx-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na+K+-dependent calcium transporter (likely NCKX4) and a Na+-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca2+, Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport

Inhibiting Na+/K+ ATPase can impair mitochondrial energetics and induce abnormal Ca2+ cycling and automaticity in guinea pig cardiomyocytes.

PubMed

Li, Qince; Pogwizd, Steven M; Prabhu, Sumanth D; Zhou, Lufang

2014-01-01

Cardiac glycosides have been used for the treatment of heart failure because of their capabilities of inhibiting Na+/K+ ATPase (NKA), which raises [Na+]i and attenuates Ca2+ extrusion via the Na+/Ca2+ exchanger (NCX), causing [Ca2+]i elevation. The resulting [Ca2+]i accumulation further enhances Ca2+-induced Ca2+ release, generating the positive inotropic effect. However, cardiac glycosides have some toxic and side effects such as arrhythmogenesis, confining their extensive clinical applications. The mechanisms underlying the proarrhythmic effect of glycosides are not fully understood. Here we investigated the mechanisms by which glycosides could cause cardiac arrhythmias via impairing mitochondrial energetics using an integrative computational cardiomyocyte model. In the simulations, the effect of glycosides was mimicked by blocking NKA activity. Results showed that inhibiting NKA not only impaired mitochondrial Ca2+ retention (thus suppressed reactive oxygen species (ROS) scavenging) but also enhanced oxidative phosphorylation (thus increased ROS production) during the transition of increasing workload, causing oxidative stress. Moreover, concurrent blocking of mitochondrial Na+/Ca2+ exchanger, but not enhancing of Ca2+ uniporter, alleviated the adverse effects of NKA inhibition. Intriguingly, NKA inhibition elicited Ca2+ transient and action potential alternans under more stressed conditions such as severe ATP depletion, augmenting its proarrhythmic effect. This computational study provides new insights into the mechanisms underlying cardiac glycoside-induced arrhythmogenesis. The findings suggest that targeting both ion handling and mitochondria could be a very promising strategy to develop new glycoside-based therapies in the treatment of heart failure.

Fluorcanasite, K3Na3Ca5Si12O30(F,OH)4 · H2O, a new mineral species from the Khibiny alkaline pluton, Kola Peninsula, Russia, and new data on canasite

NASA Astrophysics Data System (ADS)

Khomyakov, A. P.; Nechelyustov, G. N.; Krivokoneva, G. K.; Rastsvetaeva, R. K.; Rozenberg, K. A.; Rozhdestvenskaya, I. V.

2009-12-01

Fluorcanasite is described, a new mineral species found in dumps of the Kirovsk apatite mine, Mt. Kukisvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. The new mineral is associated with microcline, nepheline, aegirine, scherbakovite, lamprophyllite, pectolite, mosandrite, villiaumite, rasvumite, and molybdenite. It occurs as prismatic crystals up to 0.2-0.3 × 1-2 mm in size extending along [010]. Fluorcanasite is purple, transparent, with white streak and vitreous luster. The fracture is hackly along the extension and stepped in other directions. The mineral is brittle. The cleavage is eminent parallel to {100} and {201} and perfect parallel to {001}. D(meas) = 2.68(2) g/cm3 (volumetric method); D(calc) = 2.69 g/cm3. Fluorcanasite is biaxial, negative, n α = 1.538(1), n β = 1.546(1), n γ = 1.549(1), 2 V(meas) = 60(2)°, 2 V(calc) = 63°. Dispersion r > v. The new mineral is pleochroic according to the scheme N β > N γ > N α; N β is purple, N γ is lilac, and N α is amber-yellow. Orientation is as follows: b = N β, a∧ N γ = 3°, c∧ N α = 19°. Fluorcanasite is not luminescent in UV light and slowly decomposes in acid. The new mineral is monoclinic, space group Cm, a = 18.846(4), b = 7.242(1), c = 12.650(2) Å, β = 111.84(2)°, V = 1602.6(4) Å3, Z = 2. The strongest reflections [ d, Å( I)] in the X-ray powder pattern of a grainoriented sample are 2.915(100), 4.204(40), 5.872(36), 4.712(36), 2.358(32), 3.012(24), 2.310(24), 3.082(24) and the same reflections in a randomly oriented sample are 3.082(100), 2.915(85), 4.712(46), 4.204(41), 3.340(35), 5.872(33), 2.658(30). The chemical composition, determined with an electron microprobe, is as follows, wt %: 7.19 Na2O, 10.91 K2O, 19.55 CaO, 0.27 FeO, 2.08 MnO, 55.84 SiO2, 4.10 F, 2.22 H2O (determined on the basis of structural data), 1.73-O = F2; the total is 100.43. The empirical formula, calculated on the basis of Si = 12, is K2.99Na3.00(Ca4.50Mn0.38·Fe{0.05/2+})Σ4.93Si12O29.93(F2.79OH1

Functional significance of co-occurring mutations in PIK3CA and MAP3K1 in breast cancer.

PubMed

Avivar-Valderas, Alvaro; McEwen, Robert; Taheri-Ghahfarokhi, Amir; Carnevalli, Larissa S; Hardaker, Elizabeth L; Maresca, Marcello; Hudson, Kevin; Harrington, Elizabeth A; Cruzalegui, Francisco

2018-04-20

The PI3Kα signaling pathway is frequently hyper-activated in breast cancer (BrCa), as a result of mutations/amplifications in oncogenes (e.g. HER2 ), decreased function in tumor suppressors (e.g. PTEN ) or activating mutations in key components of the pathway. In particular, activating mutations of PIK3CA (~45%) are frequently found in luminal A BrCa samples. Genomic studies have uncovered inactivating mutations in MAP3K1 (13-20%) and MAP2K4 (~8%), two upstream kinases of the JNK apoptotic pathway in luminal A BrCa samples. Further, simultaneous mutation of PIK3CA and MAP3K1 are found in ~11% of mutant PIK3CA tumors. How these two alterations may cooperate to elicit tumorigenesis and impact the sensitivity to PI3K and AKT inhibitors is currently unknown. Using CRISPR gene editing we have genetically disrupted MAP3K1 expression in mutant PIK3CA cell lines to specifically create in vitro models reflecting the mutational status of PIK3CA and MAP3K1 in BrCa patients. MAP3K1 deficient cell lines exhibited ~2.4-fold increased proliferation rate and decreased sensitivity to PI3Kα/δ(AZD8835) and AKT (AZD5363) inhibitors (~2.61 and ~5.23-fold IC 50 increases, respectively) compared with parental control cell lines. In addition, mechanistic analysis revealed that MAP3K1 disruption enhances AKT phosphorylation and downstream signaling and reduces sensitivity to AZD5363-mediated pathway inhibition. This appears to be a consequence of deficient MAP3K1-JNK signaling increasing IRS1 stability and therefore promoting IRS1 binding to p85, resulting in enhanced PI3Kα activity. Using 3D-MCF10A-PI3Kα H1047R models, we found that MAP3K1 depletion increased overall acinar volume and counteracted AZD5363-mediated reduction of acinar growth due to enhanced proliferation and reduced apoptosis. Furthermore, in vivo efficacy studies revealed that MAP3K1-deficient MCF7 tumors were less sensitive to AKT inhibitor treatment, compared with parental MCF7 tumors. Our study provides

Binder-jetting 3D printing and alloy development of new biodegradable Fe-Mn-Ca/Mg alloys.

PubMed

Hong, Daeho; Chou, Da-Tren; Velikokhatnyi, Oleg I; Roy, Abhijit; Lee, Boeun; Swink, Isaac; Issaev, Ilona; Kuhn, Howard A; Kumta, Prashant N

2016-11-01

3D printing of various biomaterials including titanium and stainless steel has been studied for treating patients with cranio-maxillofacial bone defect. The potential long term complications with use of inert biometals have opened the opportunities for use of biodegradable metals in the clinical arena. The authors previously reported that binder-jet 3D printing technique enhanced the degradation rates of biodegradable Fe-Mn alloy by creating engineered micropores rendering the system attractive as biodegradable implantable devices. In the present study, the authors employed CALPHAD modeling to systematically study and modify the Fe-Mn alloy composition to achieve enhanced degradation rates. Accordingly, Ca and Mg addition to Fe-35wt% Mn solid solution predicted increase in degradation rates. In order to validate the CALPHAD results, Fe - (35-y)wt% Mn - ywt% X (X=Ca, Mg, and y=0, 1, 2) were synthesized by using high energy mechanical alloying (HEMA). Sintered pellets of Fe-Mn-Ca and Fe-Mn-Mg were then subjected to potentiodynamic polarization (PDP) and live/dead cell viability tests. Sintered pellets of Fe-Mn, Fe-Mn-Ca, and Fe-Mn-Mg also exhibited MC3T3 murine pre-osteoblast cells viability in the live/dead assay results. Fe-Mn and Fe-Mn-1Ca were thus accordingly selected for 3D printing and the results further confirmed enhanced degradation of Ca addition to 3D printed constructs validating the theoretical and alloy development studies. Live/dead and MTT cell viability results also confirmed good cytocompatibility of the 3D-printed Fe-Mn and Fe-Mn-1Ca constructs. Bone grafting is widely used for the treatment of cranio-maxillofacial bone injuries. 3D printing of biodegradable Fe alloy is anticipated to be advantageous over current bone grafting techniques. 3D printing offers the fabrication of precise and tailored bone grafts to fit the patient specific bone defect needs. Biodegradable Fe alloy is a good candidate for 3D printing synthetic grafts to regenerate bone

Thermodynamic properties of Na2O-SiO2-CaO melts at 1000 to 1100 °C

NASA Astrophysics Data System (ADS)

Neudorf, D. A.; Elliott, J. F.

1980-12-01

The thermodynamic properties of Na2O-SiO2 and Na2O-SiO2-CaO melts have been measured using the galvanic cellbegin{array}{*{20}c} {O_2 (g), (Na_2 O), Pt} \\ {Na_2 O - WO_3 liq} \\ left| begin{gathered} Na^ + \\ β - alumina \\ right| begin{array}{*{20}c} {Pt,(Na_2 O), O_2 (g)} \\ {Na_2 O - SiO_2 - CaO liq} \\ Activities of Na2O were calculated from the reversible emf of the cell. This is possible because the activity of Na2O in the Na2O-WO3 liquid is known from previous work. Data for the binary Na2O-SiO2 system were obtained between 1000 and 1100 °C and for compositions ranging from 25 wt pct to 40 wt pct Na2O. At 1050 °C, Loga_{Na_2 O} varied from approximately 10.2 at 25 wt pct Na2O to approximately -8.3 at 40 wt pct Na2O, the dependence with respect to composition being nearly linear. The Gibbs-Duhem equation was used to calculate the activities of SiO2(s), and the integral mixing properties, G M, HM, and S M, were derived. At the di-silicate composition, G M = -83 kJ/mol, H M = -41 kJ mol and S M = 33 J/mol K at 1000 °C. (Standard states are pure, liquid Na2O and pure, solid tridymite.) The activity data are interpreted in terms of the polymeric nature of silicate melts. Activities of Na2O in the Na2O-CaO-SiO2 system were measured for the 25, 30 and 35 wt pct Na2O binary compositions with up to 10 wt pct CaO added. The addition of CaO caused an increase in the activity of Na2O at constantN_{Na_2 O} /N_{SiO_2 } . The experimental data agree well with the behavior predicted by Richardson’s ternary mixing model.

Analysis of the Na+/Ca2+ Exchanger Gene Family within the Phylum Nematoda

PubMed Central

He, Chao; O'Halloran, Damien M.

2014-01-01

Na+/Ca2+ exchangers are low affinity, high capacity transporters that rapidly transport calcium at the plasma membrane, mitochondrion, endoplasmic (and sarcoplasmic) reticulum, and the nucleus. Na+/Ca2+ exchangers are widely expressed in diverse cell types where they contribute homeostatic balance to calcium levels. In animals, Na+/Ca2+ exchangers are divided into three groups based upon stoichiometry: Na+/Ca2+ exchangers (NCX), Na+/Ca2+/K+ exchangers (NCKX), and Ca2+/Cation exchangers (CCX). In mammals there are three NCX genes, five NCKX genes and one CCX (NCLX) gene. The genome of the nematode Caenorhabditis elegans contains ten Na+/Ca2+ exchanger genes: three NCX; five CCX; and two NCKX genes. Here we set out to characterize structural and taxonomic specializations within the family of Na+/Ca2+ exchangers across the phylum Nematoda. In this analysis we identify Na+/Ca2+ exchanger genes from twelve species of nematodes and reconstruct their phylogenetic and evolutionary relationships. The most notable feature of the resulting phylogenies was the heterogeneous evolution observed within exchanger subtypes. Specifically, in the case of the CCX exchangers we did not detect members of this class in three Clade III nematodes. Within the Caenorhabditis and Pristionchus lineages we identify between three and five CCX representatives, whereas in other Clade V and also Clade IV nematode taxa we only observed a single CCX gene in each species, and in the Clade III nematode taxa that we sampled we identify NCX and NCKX encoding genes but no evidence of CCX representatives using our mining approach. We also provided re-annotation for predicted CCX gene structures from Heterorhabditis bacteriophora and Caenorhabditis japonica by RT-PCR and sequencing. Together, these findings reveal a complex picture of Na+/Ca2+ transporters in nematodes that suggest an incongruent evolutionary history of proteins that provide central control of calcium dynamics. PMID:25397810

Extraction of Mg(OH)2 from Mg silicate minerals with NaOH assisted with H2O: implications for CO2 capture from exhaust flue gas.

PubMed

Madeddu, Silvia; Priestnall, Michael; Godoy, Erik; Kumar, R Vasant; Raymahasay, Sugat; Evans, Michael; Wang, Ruofan; Manenye, Seabelo; Kinoshita, Hajime

2015-01-01

The utilisation of Mg(OH)2 to capture exhaust CO2 has been hindered by the limited availability of brucite, the Mg(OH)2 mineral in natural deposits. Our previous study demonstrated that Mg(OH)2 can be obtained from dunite, an ultramafic rock composed of Mg silicate minerals, in highly concentrated NaOH aqueous systems. However, the large quantity of NaOH consumed was considered an obstacle for the implementation of the technology. In the present study, Mg(OH)2 was extracted from dunite reacted in solid systems with NaOH assisted with H2O. The consumption of NaOH was reduced by 97% with respect to the NaOH aqueous systems, maintaining a comparable yield of Mg(OH)2 extraction, i.e. 64.8-66%. The capture of CO2 from a CO2-N2 gas mixture was tested at ambient conditions using a Mg(OH)2 aqueous slurry. Mg(OH)2 almost fully dissolved and reacted with dissolved CO2 by forming Mg(HCO3)2 which remained in equilibrium storing the CO2 in the aqueous solution. The CO2 balance of the process was assessed from the emissions derived from the power consumption for NaOH production and Mg(OH)2 extraction together with the CO2 captured by Mg(OH)2 derived from dunite. The process resulted as carbon neutral when dunite is reacted at 250 °C for durations of 1 and 3 hours and CO2 is captured as Mg(HCO3)2.

The Na+/Ca2+, K+ exchanger NCKX4 is required for efficient cone-mediated vision

PubMed Central

Vinberg, Frans; Wang, Tian; De Maria, Alicia; Zhao, Haiqing; Bassnett, Steven; Chen, Jeannie; Kefalov, Vladimir J

2017-01-01

Calcium (Ca2+) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na+/Ca2+, K+ exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival. DOI: http://dx.doi.org/10.7554/eLife.24550.001 PMID:28650316

Effects of hyper- and hypothyroidism on acetylcholinesterase, (Na(+), K (+))- and Mg ( 2+ )-ATPase activities of adult rat hypothalamus and cerebellum.

PubMed

Carageorgiou, Haris; Pantos, Constantinos; Zarros, Apostolos; Stolakis, Vasileios; Mourouzis, Iordanis; Cokkinos, Dennis; Tsakiris, Stylianos

2007-03-01

Thyroid hormones (THs) are recognized as key metabolic hormones, and the metabolic rate increases in hyperthyroidism, while it decreases in hypothyroidism. The aim of this work was to investigate how changes in metabolism induced by THs could affect the activities of acetylcholinesterase (AChE), (Na(+), K(+))- and Mg(2+)-ATPase in the hypothalamus and the cerebellum of adult rats. Hyperthyroidism was induced by subcutaneous administration of thyroxine (25 microg/100 g body weight) once daily for 14 days, while hypothyroidism was induced by oral administration of propylthiouracil (0.05%) for 21 days. All enzyme activities were evaluated spectrophotometrically in the homogenated brain regions of 10 three-animal pools. Neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE (-23%, p < 0.001) and the Na(+), K(+)-ATPase activities (-26%, p < 0.001). Moreover, hypothyroidism had a similar effect on the examined enzyme activities: AChE (-17%, p < 0.001) and Na(+), K(+)-ATPase (-27%, p < 0.001). Mg(2+)-ATPase activity was found unaltered in both the hyper- and the hypothyroid brain regions. neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE and the Na(+), K(+)-ATPase activities. The decreased (by the THs) Na(+), K(+)-ATPase activities may increase the synaptic acetylcholine release, and thus, could result in a decrease in the cerebellar AChE activity. Moreover, the above TH-induced changes may affect the monoamine neurotransmitter systems.