Sample records for hydrated sodium calcium

  1. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729 Section...Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  2. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Sodium calcium aluminosilicate, hydrated. 182...Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  3. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Sodium calcium aluminosilicate, hydrated. 182...Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  4. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Sodium calcium aluminosilicate, hydrated. 182...Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  5. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Sodium calcium aluminosilicate, hydrated. 182...Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  6. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729 Section...Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  7. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729 Section...Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  8. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729 Section...Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  9. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729 Section...Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  10. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Sodium calcium aluminosilicate, hydrated. 182...Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  11. Dietary Hydrated Sodium Calcium Aluminosilicate Reduction of Aflatoxin M, Residue in Dairy Goat Milk and Effects on Milk Production and Components'r2

    Microsoft Academic Search

    Ernest E. Smith; Timothy D. Phillips; Jeffery A. Ellis; Roger B. Harvey; Leon F. Kubena; Jennifer Thompson; Gary Newton

    2009-01-01

    Lactating dairy goats were exposed to aflatoxin (100 and 200 ppb) and hydrated sodium calcium aluminosilicate at 1, 2, and 4% in two separate experiments. Naturally occurring low levels of aflatoxin M1 (.009 ppb) were found in the milk of the control diet, whereas there were no detectable levels of aflatoxin M1 in the milk of diets containing hydrated sodium

  12. Efficacy of hydrated sodium calcium aluminosilicate and activated charcoal in reducing the toxicity of dietary aflatoxin to mink

    Microsoft Academic Search

    R. J. Bonna; R. J. Aulerich; S. J. Bursian; R. H. Poppenga; W. E. Braselton; G. L. Watson

    1991-01-01

    Mink were fed diets that contained 0, 34, or 102 ppb (µg\\/kg) aflatoxins with or without 0.5% hydrated sodium calcium aluminosilicate (HSCAS) and\\/or 1.0% activated charcoal (AC) for 77 days. Consumption of the diet that contained 34 ppb aflatoxins was lethal to 20% of the mink, while 102 ppb dietary aflatoxins resulted in 100% mortality within 53 days. The addition

  13. Thermochemistry of hydrated calcium borates

    Microsoft Academic Search

    Jun Li; Shiyang Gao; Shuping Xia; Bing Li; Rongzu Hu

    1997-01-01

    The enthalpies of solution of five hydrated calcium borates in approximately 1 mol·dm?3aqueous hydrochloric acid were determined. From a combination of these results with measured enthalpies of solution of H3BO3in HCl(aq) and of CaO in (hydrochloric acid+boric acid) (aq), together with the standard molar enthalpies of formation of CaO(s), H3BO3(S), and H2O(l), the standard molar enthalpies of formation of the

  14. Efficiency of hydrated sodium calcium aluminosilicate to ameliorate the adverse effects of graded levels of aflatoxin B1 in broiler chicks.

    PubMed

    Chen, X; Horn, N; Applegate, T J

    2014-08-01

    The objective of this study was to evaluate the efficiency of a hydrated sodium calcium aluminosilicate (HSCAS) adsorbent to ameliorate the adverse effects of 0.5 to 2 mg of aflatoxin B1 (AFB1)/kg in broiler chicks. The study consisted of 8 dietary treatments, including 4 concentrations of AFB1 (0, 0.5, 1, and 2 mg/kg) with or without HSCAS (0.5%) fed to 8 replicate cages per diet (6 males chicks per cage) from 0 to 21 d of age. Cumulative feed intake, BW gain (P < 0.0001), and G:F (P = 0.004) of birds fed the 2 mg of AFB1/kg of diet were significantly lower in comparison with birds fed 0 to 1 mg of AFB1/kg. Relative liver weight was increased in the 2 mg of AFB1/kg group (P < 0.0001). Dietary HSCAS improved cumulative BW gain (main effect P = 0.06), particularly from 14 to 21 d of age (P = 0.037). Dietary HSCAS also reversed the increase in relative liver weight for birds fed AFB1 (P = 0.019). Dietary AFB1 negatively affected major serum parameters (albumin, total protein, globulin, phosphorus, glucose, alkaline phosphatase, and creatine phosphokinase), whereas supplementation with HSCAS partially alleviated the affected serum biochemistry. In addition, serum complement activity and liver gene expression were negatively affected by 2 mg of AFB1/kg. The HSCAS supplement increased the liver expression of catalase and superoxide dismutase (P < 0.05). Results from this study indicate that dietary supplementation with HSCAS can effectively improve BW gain and partially ameliorate aflatoxicosis for broiler chicks fed AFB1-contaminated feeds. PMID:24894529

  15. In vitro and in vivo efficacy of a hydrated sodium calcium aluminosilicate to bind and reduce aflatoxin residues in tissues of broiler chicks fed aflatoxin B1.

    PubMed

    Neeff, D V; Ledoux, D R; Rottinghaus, G E; Bermudez, A J; Dakovic, A; Murarolli, R A; Oliveira, C A F

    2013-01-01

    The aim of this study was to determine the binding capacity of a hydrated sodium calcium aluminosilicate (HSCAS) for aflatoxin B(1) (AFB(1)), and the efficacy of the HSCAS to reduce the concentrations of residual AFB(1) and its metabolites in the liver and kidney of broilers fed AFB(1). One hundred 1-d-old male broilers (Ross 708) were maintained in chick batteries and allowed ad libitum access to feed and water. A completely randomized design was used with 5 replicate pens of 5 chicks assigned to each of 4 dietary treatments from hatch to 21 d. Dietary treatments included the following: A) basal diet (BD), with no HSCAS or AFB(1), B) BD supplemented with 0.5% HSCAS only, C) BD supplemented with 2.5 mg of AFB(1)/kg of feed, and D) BD supplemented with 2.5 mg of AFB(1)/kg of feed and 0.5% HSCAS. On d 21, 5 chicks from each treatment were anesthetized with carbon dioxide, killed by cervical dislocation, and samples of liver and kidney were collected for analysis of AFB(1) residues. The percentage of AFB(1) bound for each concentration of adsorbent (100, 10, 1, 0.5, 0.25, and 0.05 mg/10 mL) was 100, 91.1, 81.8, 75.4, 40.1, and 8.8%, respectively. Concentrations of aflatoxin residues (AFB(1), aflatoxicol, aflatoxins B(2) and G(1)) were lower (P < 0.05) in livers and kidneys of birds fed AFB(1) plus HSCAS (diet D), when compared with birds fed AFB(1) alone (diet C). However, histopathology data from the in vivo study indicated that HSCAS did not prevent lesions associated with aflatoxicosis. The decrease in the bioavailability of AFB(1) caused by the HSCAS reduced aflatoxin residues in liver and kidney, but not enough to completely prevent the toxic effects of AFB(1) in broilers. PMID:23243239

  16. Halting the calcium aluminate cement hydration process

    Microsoft Academic Search

    A. P. Luz; V. C. Pandolfelli

    2011-01-01

    Calcium aluminate cement reactions with water result in anhydrous phases dissolution, followed by nucleation and crystal growth of hydrate compounds. Due to the dynamic characteristics of this process and in order to evaluate the phase transformation kinetics of such materials, suitable methods to halt hydration are required. In this work, the use of acetone and microwave drying, aiming to withdraw

  17. MICROCALORIMETRIC STUDY ON CALCIUM ALUMINATE CEMENT HYDRATION

    Microsoft Academic Search

    Neven Ukrainczyk; Pero Dabi?

    Calcium aluminate cement (CAC) is very versatile special cement used for specific applications. During the hydration of CAC a large quantity of heat is liberated within one day that causes a considerable increase of temperature in material. This paper examines the hydration of three samples (A, B and aged B) of commercial CAC ISTRA 40 (producer: Istra Cement, Pula, Croatia).

  18. Characterization of hydrated sodium molybdenum bronzes

    SciTech Connect

    Sotani, Noriyuki; Eda, Kazuo; Kunitomo, Masakazu (Kobe Univ. (Japan))

    1990-11-01

    Two kinds of hydrated sodium molybdenum bronzes, an air-dried bronze (AD) and a vacuum dried one (VD), are characterized using x-ray diffraction, TG-DTA, IR spectroscopy, and NMR. According to NMR results, the paired protons and a small amount of isolated protons fixed in position are included both in AD and VD. It is found that the hydrate-water (HW) in VD exists basically in the form of hydrated sodium ion, Na{sup +}(H{sub 2}O){sub 2}, where Na{sup +} coordinates with four terminal oxygens of an (MoO{sub 6}) octahedron of MoO{sub 3} and two oxygens of hydrate-water (HW-2). The composition of VD has been determined as (Na(H{sub 2}O){sub 1.95}){sub 0.22}H{sub 0.03}MoO{sub 3.11}. In addition to HW-2, AD includes another hydrate-water (HW-1), which is easily removed by drying in vacuo and/or by standing in air. The composition of AD has been determined as (Na(H{sub 2}O){sub 2+2.26}){sub 0.23}H{sub 0.02}MoO{sub 3.10}.

  19. Electronic structure calculations of calcium silicate hydrates

    SciTech Connect

    Sterne, P.A. [Univ. of California, Davis, CA (United States). Dept. of Physics]|[Lawrence Livermore National Lab., CA (United States); Meike, A. [Lawrence Livermore National Lab., CA (United States)

    1995-11-01

    Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO{sub 3}) and xonotlite (Ca{sub 6}Si{sub 6}O{sub 17}(OH){sub 2}), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases.

  20. Hydroxyapatite formation from a hydrated calcium monohydrogen phosphate precursor

    Microsoft Academic Search

    Marion D. Francis; Ned C. Webb

    1970-01-01

    Hydrated calcium monohydrogen phosphate is proposed as the logical precursor in the formation of hydroxyapatite and a unifying theory for the formation of low calcium, or defect apatites, is presented. Structural relationships between calcium monohydrogen phosphate dihydrate and hydroxyapatite indicate that either material can provide the atomic arrangment for the epitaxial growth of one on the other. The formation of

  1. The hydration of interstitial Portland cement phases in sodium hydroxide and magnesium sulfate solutions

    NASA Astrophysics Data System (ADS)

    Clark, Boyd Arthur

    Formation of sulfoaluminate compounds was investigated by isothermal calorimetry and X-ray diffraction (XRD). Tricalcium aluminate/gypsum mixtures with a molar ratio of 1:1 sulfate-to-aluminate were hydrated at constant temperatures from 30 to 90°C; in de-ionized water, in 200mM and in 500mM sodium hydroxide (NaOH) solutions. Hydration in de-ionized water produced ettringite and monosulfate as the dominant crystalline phases, regardless of temperature. Complex assemblages of phases formed in 200mM and 500mM sodium hydroxide including ettringite, monosulfate and U-phase, at all temperatures. Hydration of monosulfate and gypsum was also carried out at constant temperatures from 30° to 80°C using de-ionized water and 0.2M, 0.5M, and 1.0M sodium hydroxide (NaOH) solutions. Ettringite was found to be the dominant crystalline phase over the entire temperature range and at all sodium hydroxide concentrations. A sodium-substituted monosulfate phase was formed as a hydration product in the 1.0M sodium hydroxide solution regardless of temperature. Sulfoaluminate compounds formed by tricalcium aluminate hydration in magnesium sulfate solution were investigated by isothermal calorimetry, XRD, and scanning electron microscopy (SEM). Hydration was carried out in 0.5, 1.0 and 3.0M magnesium sulfate solutions and isothermally at temperatures from 30 to 80°C. Monosulfate, ettringite, gypsum and a hydrogarnet phase (Ca3Al2O6·6H2O) were all observed as hydration products. Monosulfate and hydrogarnet were the only phases observed for hydration in 0.5 and 1.0M magnesium sulfate solutions. Ettringite was the dominant crystalline phase after hydration in 3.0M solution, regardless of temperature. To investigate the rate of hydration, reactions at 60°C in 3.0M magnesium sulfate solution were quenched after 26 minutes, 73 minutes, 2.5 hours and 12 hours to establish the evolution of hydrated phases. Depending on hydration times ettringite, monosulfate, gypsum, hydrogarnet and residual tricalcium aluminate were observed. No crystalline magnesium-rich phases were detected by XRD. The products formed by hydration of tetracalcium aluminoferrite (Ca 2AlFeO5) and magnesium sulfate solutions were investigated by isothermal calorimetry, XRD and SEM analyses. Hydration reactions were carried out isothermally at temperatures from 25 to 80°C in 0.25M, 0.5M, 1.0M, 2.0M, and 3.0M magnesium sulfate solutions. Gypsum was the initial hydration product in all magnesium sulfate concentrations and was the only crystalline hydration product in 2.0M and 3.0M magnesium sulfate solutions. Monosulfate was the dominant crystalline phase produced over the entire temperature range when hydration was carried out in magnesium sulfate concentrations between 0.25M and 1.0M. No crystalline phases incorporating iron were observed regardless of magnesium sulfate concentration or temperature. Hydration in 1.0M MgSO 4 solution was more extensively investigated at 50°C. SEM observations indicated gypsum formed initially, consisting of fine particles (<5 mum). Complex phase assemblages including gypsum, ettringite, and monosulfate were present at intermediate times. Monosulfate was the final crystalline hydration product. Amorphous solids produced include a calcium/iron-rich gel and a magnesium/aluminum/sulfate-rich phase. The calcium/iron-rich gel is the only iron-rich phase observed in the hydrated phase assemblage.

  2. The nanostructure of calcium silicate hydrate

    NASA Astrophysics Data System (ADS)

    Chen, Jeffrey J.

    The nanostructure of C-S-H, the principle binding phase of hydrated cements in concrete, is examined through classical and spectroscopic methods such as solubility, 29Si MAS NMR, inelastic neutron scattering (INS), and small-angle neutron scattering (SANS). A more comprehensive understanding of the nanostructure is proposed. The central finding of this thesis is that variations in Ca/Si ratio, silicate structure, and Ca-OH content of C-S-H are systematically related to previously undiscovered variations in solubility in the CaO-SiO2-H 2O system at room temperature. These relationships show how C-S-H resembles disordered forms of the calcium silicate hydrate minerals 1.4-nm tobermorite [Ca5Si6O16(OH)2·8H 2O] and jennite [Ca9(Si6O18)(OH) 6·8H2O]. For example, in solids lacking Ca-OH groups, the structure resembles a purely tobermorite-like structure, which, when equilibrated in aqueous solutions saturated in Ca(OH)2, has a Ca/Si ratio of 1.5 and a minimum mean silicate chain length of 2; with increasing Ca-OH contents, the structure becomes increasingly jennite-like while showing higher Ca/Si ratios and higher mean chain lengths at saturation in Ca(OH)2. These relationships appear to reconcile the broad variations in the literature. 29Si NMR on concrete specimens aged 43--96 years show that the mean silicate chain length of C-S-H gel ultimately converges to a value of 5. With supporting evidence from chemical analysis and from high Ca-OH contents measured by INS, it is concluded that C-S-H gel formed in Ca3SiO5 pastes eventually equilibrates to a purely jennite-like structure. A Ca/Si ratio of 1.2 in C-S-H gel marks the composition at which Ca-OH groups are eliminated (or introduced) and below which spontaneous silicate polymerization occurs. Leaching studies on cement pastes show that when C-S-H is decalcified below Ca/Si ˜ 1.2, the induced silicate polymerization occurring in situ leads to macroscopic polymerization shrinkage. Cement pastes blended with high contents of mineral additions may be more susceptible to this mechanism. SANS measurements on leached Ca3SiO5 and cement pastes show dramatic variations in surface area with Ca/Si ratio. These variations are attributed to transformations between low- and high-density morphologies of C-S-H.

  3. Dynamic behavior of hydration water in calcium-silicate-hydrate gel: A quasielastic neutron scattering spectroscopy investigation

    E-print Network

    Li, Hua

    The translational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel was studied by quasielastic neutron scattering spectroscopy in the temperature range from 280 to 230 K. The stretch exponent ...

  4. Sodium Removal from Hanford Waste Simulants Using Hydrated Antimony Pentoxide

    Microsoft Academic Search

    Tovo

    1999-01-01

    Sodium has been removed from each of the three Hanford waste simulants with Hydrated Antimony Pentoxide (HAP) to facilitate technetium measurement by ICP-MS. Technetium was successfully measured in simulants A and B with small dilutions of the simulants (10x). Matrix interference, probably due to organic components, prevented the accurate measurement of Tc in simulant C. HAP has been used for

  5. 21 CFR 573.280 - Feed-grade calcium stearate and sodium stearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Feed-grade calcium stearate and sodium stearate. 573.280...Additive Listing § 573.280 Feed-grade calcium stearate and sodium stearate. Feed-grade calcium stearate and sodium stearate may be...

  6. 21 CFR 573.280 - Feed-grade calcium stearate and sodium stearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Feed-grade calcium stearate and sodium stearate. 573.280...Additive Listing § 573.280 Feed-grade calcium stearate and sodium stearate. Feed-grade calcium stearate and sodium stearate may be...

  7. 21 CFR 573.280 - Feed-grade calcium stearate and sodium stearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Feed-grade calcium stearate and sodium stearate. 573.280...Additive Listing § 573.280 Feed-grade calcium stearate and sodium stearate. Feed-grade calcium stearate and sodium stearate may be...

  8. 21 CFR 573.280 - Feed-grade calcium stearate and sodium stearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 false Feed-grade calcium stearate and sodium stearate. 573.280...Additive Listing § 573.280 Feed-grade calcium stearate and sodium stearate. Feed-grade calcium stearate and sodium stearate may be...

  9. The role of calcium ions and lignosulphonate plasticiser in the hydration of cement

    SciTech Connect

    Grierson, L.H.; Knight, J.C.; Maharaj, R

    2005-04-01

    Experiments involving equilibrium dialysis, conductivity, X-ray diffraction analysis (XRD), differential thermal analysis (DTA) and isothermal titration calorimetry (ITC) have been carried out to investigate the role of calcium ions and polymeric plasticisers in cement/admixture hydration. Results from a study of lignosulphonic acid, sodium salt, acetate as a plasticiser shows that a plasticiser has dual role; one mainly as a kinetic inhibitor (poison) in cement hydration mechanism and the other as a dispersant. Evidence of a weak Ca{sup 2+} binding to lignosulphonate sulphonic moieties was found at low ionic strengths of 0.1 M using ITC. No evidence of formal Ca{sup 2+} binding to lignosulphonate sulphonic acid moieties was found using equilibrium dialysis at higher ionic strength of 1 M (ionic strengths of 0.4 M are typically found in Portland cement pore solution), as is often suggested in cement/admixture literature.

  10. Uptake of chloride and carbonate ions by calcium monosulfoaluminate hydrate

    SciTech Connect

    Mesbah, Adel [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); Cau-dit-Coumes, Celine, E-mail: celine.cau-dit-coumes@cea.fr [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Renaudin, Guillaume [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, F-63177 Aubiere (France); Frizon, Fabien [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Leroux, Fabrice [Clermont Universite, Universite Blaise Pascal, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, F-63177 Aubiere (France)

    2012-08-15

    Decommissioning of old nuclear reactors may produce waste streams containing chlorides and carbonates, including radioactive {sup 36}Cl{sup -} and {sup 14}CO{sub 3}{sup 2-}. Their insolubilization by calcium monosulfoaluminate hydrate was investigated. Carbonates were readily depleted from the solution, giving at thermodynamic equilibrium monocarboaluminate, monocarboaluminate + calcite, or calcite only, depending on the initial ratio between the anion and calcium monosulfoaluminate hydrate. Chloride ions reacted more slowly and were precipitated as Kuzel's salt, Kuzel's and Friedel's salts, or Friedel's salt only. Rietveld refinement of X-Ray powder diffraction patterns was successfully used to quantify the phase distributions, which were compared to thermodynamic calculations. Moreover, analysing the lattice parameters of Kuzel's salt as a function of its chloride content showed the occurrence of a restricted solid solution towards the sulfate side with general formula 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}xCaCl{sub 2}{center_dot}(1 - x)CaSO{sub 4}{center_dot}(12 - 2x){center_dot}H{sub 2}O (0.36 {<=} x {<=} 0.50).

  11. Calcium and sodium bentonite for hydraulic containment applications

    Microsoft Academic Search

    Mark H. Gleason; David E. Daniel; Gerald R. Eykholt

    1997-01-01

    The hydraulic conductivity of calcium and sodium bentonites was investigated for sand-bentonite mixtures, a thin bentonite layer simulating a geosynthetic clay liner (GCL), and bentonite-cement mixtures simulating backfill for a vertical cutoff wall. The permeant liquids were tap water and distilled water containing 0.25 M calcium chloride. In general, the hydraulic performance of calcium bentonite was not significantly better than

  12. Hydration studies of calcium sulfoaluminate cements blended with fly ash

    SciTech Connect

    García-Maté, M.; De la Torre, A.G. [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga (Spain)] [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga (Spain); León-Reina, L. [Servicios Centrales de Apoyo a la Investigación, Universidad de Málaga, 29071 Málaga (Spain)] [Servicios Centrales de Apoyo a la Investigación, Universidad de Málaga, 29071 Málaga (Spain); Aranda, M.A.G. [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga (Spain) [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga (Spain); CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); Santacruz, I., E-mail: isantacruz@uma.es [Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga (Spain)

    2013-12-15

    The main objective of this work is to study the hydration and properties of calcium sulfoaluminate cement pastes blended with fly ash (FA) and the corresponding mortars at different hydration ages. Laboratory X-ray powder diffraction, rheological studies, thermal analysis, porosimetry and compressive strength measurements were performed. The analysis of the diffraction data by Rietveld method allowed quantifying crystalline phases and overall amorphous contents. The studied parameters were: i) FA content, 0, 15 and 30 wt.%; and ii) water addition, water-to-CSA mass ratio (w/CSA = 0.50 and 0.65), and water-to-binder mass ratio (w/b = 0.50). Finally, compressive strengths after 6 months of 0 and 15 wt.% FA [w/CSA = 0.50] mortars were similar: 73 ± 2 and 72 ± 3 MPa, respectively. This is justified by the filler effect of the FA as no strong evidences of reactivity of FA with CSA were observed. These results support the partial substitution of CSA cements with FA with the economic and environmental benefits.

  13. Effect on the Hydration and Orientation of the Phosphate Group of DPPC at Air-Water and Air-Hydrated Silica Interfaces

    E-print Network

    with surface pressure measurements. In the LE phase, both sodium and calcium affect the phosphate group hydration. In the LC phase, however, sodium ions affect the phosphate hydration subtly, while calcium ionsNa+ and Ca2+ Effect on the Hydration and Orientation of the Phosphate Group of DPPC at Air

  14. Kinetics of tricalcium aluminate and tetracalcium aluminoferrite hydration in the presence of calcium sulfate

    Microsoft Academic Search

    Paul Wencil Brown

    1993-01-01

    Hydration reactions of C[sub 3]A with C[sub 4]AF with calcium sulfate hemihydrate and gypsum were investigated and the kinetics of the reactions compared. The rates of C[sub 3]A and C[sub 4]AF hydration, as determined by heat evolution, vary depending on whether the sulfate-containing reactant is gypsum or calcium sulfate hemihydrate. The following sequence of reactions involving C[sub 4]AF occurs when

  15. Sodium sulfate heptahydrate: a synchrotron energy-dispersive diffraction study of an elusive metastable hydrated salt 

    E-print Network

    Hamilton, Andrea; Hall, Christopher

    2008-01-01

    We describe an unusual application of synchrotron energy-dispersive diffraction with hard X-rays to obtain structural information on metastable sodium sulfate heptahydrate. This hydrate was often mentioned in nineteenth ...

  16. Influence of crystal hydration on the mechanical properties of sodium naproxen

    Microsoft Academic Search

    Etienne Joiris; Piera Di Martino; Ledjan Malaj; Roberta Censi; Christine Barthélémy; Pascal Odou

    2008-01-01

    The aim of this work is to establish a correlation between water uptake by anhydrous sodium naproxen (ASN) at two different relative humidities and modifications in tableting and densification behaviour under hydration. Water uptake was evaluated at different relative humidities. Models for the hydration kinetics of ASN at 55% and 86%, corresponding to the formation of the dihydrated and tetrahydrated

  17. Pressure induced reactions amongst calcium aluminate hydrate phases

    SciTech Connect

    Moon, Ju-hyuk [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States); Oh, Jae Eun [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan Metropolitan City, 689-798 (Korea, Republic of); Balonis, Magdalena; Glasser, Fredrik P. [Department of Chemistry, Meston Building, University of Aberdeen, Aberdeen, AB24 3UE Scotland (United Kingdom); Clark, Simon M. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA20015 (United States); Department of Earth and Planetary Sciences, University of California, Berkeley, CA94720 (United States); Monteiro, Paulo J.M., E-mail: monteiro@berkeley.ed [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2011-06-15

    The compressibilities of two AFm phases (straetlingite and calcium hemicarboaluminate hydrate) and hydrogarnet were obtained up to 5 GPa by using synchrotron high-pressure X-ray powder diffraction with a diamond anvil cell. The AFm phases show abrupt volume contraction regardless of the molecular size of the pressure-transmitting media. This volume discontinuity could be associated to a structural transition or to the movement of the weakly bound interlayer water molecules in the AFm structure. The experimental results seem to indicate that the pressure-induced dehydration is the dominant mechanism especially with hygroscopic pressure medium. The Birch-Murnaghan equation of state was used to compute the bulk modulus of the minerals. Due to the discontinuity in the pressure-volume diagram, a two stage bulk modulus of each AFm phase was calculated. The abnormal volume compressibility for the AFm phases caused a significant change to their bulk modulus. The reliability of this experiment is verified by comparing the bulk modulus of hydrogarnet with previous studies.

  18. Interactive effects of sodium chloride, sodium sulfate, calcium sulfate, and calcium chloride on snapbean growth, photosynthesis, and ion uptake

    Microsoft Academic Search

    S. Awada; W. F. Campbell; L. M. Dudley; J. J. Jurinak; M. A. Khan

    1995-01-01

    Excessive sodium (Na) accumulation in soil, which can be a problem for production agriculture in arid and semiarid regions, may be ameliorated by calcium (Ca). The mechanisms of Ca amelioration of Na stress in plants have received much more attention than has the effect of the anion of the Ca salt. Our objective was to determine the relative effects of

  19. Sodium entry through endothelial store-operated calcium entry channels: regulation by Orai1.

    PubMed

    Xu, Ningyong; Cioffi, Donna L; Alexeyev, Mikhail; Rich, Thomas C; Stevens, Troy

    2015-02-15

    Orai1 interacts with transient receptor potential protein of the canonical subfamily (TRPC4) and contributes to calcium selectivity of the endothelial cell store-operated calcium entry current (ISOC). Orai1 silencing increases sodium permeability and decreases membrane-associated calcium, although it is not known whether Orai1 is an important determinant of cytosolic sodium transitions. We test the hypothesis that, upon activation of store-operated calcium entry channels, Orai1 is a critical determinant of cytosolic sodium transitions. Activation of store-operated calcium entry channels transiently increased cytosolic calcium and sodium, characteristic of release from an intracellular store. The sodium response occurred more abruptly and returned to baseline more rapidly than did the transient calcium rise. Extracellular choline substitution for sodium did not inhibit the response, although 2-aminoethoxydiphenyl borate and YM-58483 reduced it by ?50%. After this transient response, cytosolic sodium continued to increase due to influx through activated store-operated calcium entry channels. The magnitude of this sustained increase in cytosolic sodium was greater when experiments were conducted in low extracellular calcium and when Orai1 expression was silenced; these two interventions were not additive, suggesting a common mechanism. 2-Aminoethoxydiphenyl borate and YM-58483 inhibited the sustained increase in cytosolic sodium, only in the presence of Orai1. These studies demonstrate that sodium permeates activated store-operated calcium entry channels, resulting in an increase in cytosolic sodium; the magnitude of this response is determined by Orai1. PMID:25428882

  20. Synthesis and single crystal structure refinement of the one-layer hydrate of sodium brittle mica

    SciTech Connect

    Kalo, Hussein; Milius, Wolfgang [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)] [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany); Braeu, Michael [BASF Construction Chemicals GmbH, 83308 Trostberg (Germany)] [BASF Construction Chemicals GmbH, 83308 Trostberg (Germany); Breu, Josef, E-mail: Josef.Breu@uni-bayreuth.de [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)] [Lehrstuhl fuer Anorganische Chemie I, University of Bayreuth, D-95440 Bayreuth (Germany)

    2013-02-15

    A sodium brittle mica with the ideal composition [Na{sub 4}]{sup inter}[Mg{sub 6}]{sup oct}[Si{sub 4}Al{sub 4}]{sup tet}O{sub 20}F{sub 4} was synthesized via melt synthesis in a gas tight crucible. This mica is unusual inasmuch as the known mica structure holds only room for two interlayer cations per unit cell and inasmuch as it readily hydrates despite the high layer charge while ordinary micas and brittle micas are non-swelling. The crystal structure of one-layer hydrate sodium brittle mica was determined and refined from single crystal X-ray data. Interlayer cations reside at the center of the distorted hexagonal cavities and are coordinated by the three inner basal oxygen atoms. The coordination of the interlayer cation is completed by three interlayer water molecules residing at the center of the interlayer region. The relative position of adjacent 2:1-layers thus is fixed by these octahedrally coordinated interlayer cations. Pseudo-symmetry leads to extensive twinning. In total five twin operations generate the same environment for the interlayer species and are energetically degenerate. - Graphical abstract: The sodium brittle mica has been successfully synthesized by melt synthesis and the crystal structure of the one-layer hydrate of sodium brittle mica was determined from single crystal X-ray diffraction data. Highlights: Black-Right-Pointing-Pointer Melt synthesis yielded coarse grained sodium brittle mica which showed little disorder. Black-Right-Pointing-Pointer Sodium brittle mica hydrated completely to the state of one-layer hydrate. Black-Right-Pointing-Pointer Structure of one-layer hydrate of sodium brittle mica could therefore be determined and refined. Black-Right-Pointing-Pointer Arrangement of upper and lower tetrahedral sheet encompassing interlayer cation were clarified.

  1. Kinetics of tricalcium aluminate and tetracalcium aluminoferrite hydration in the presence of calcium sulfate

    SciTech Connect

    Brown, P.W. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering)

    1993-12-01

    Hydration reactions of C[sub 3]A with C[sub 4]AF with calcium sulfate hemihydrate and gypsum were investigated and the kinetics of the reactions compared. The rates of C[sub 3]A and C[sub 4]AF hydration, as determined by heat evolution, vary depending on whether the sulfate-containing reactant is gypsum or calcium sulfate hemihydrate. The following sequence of reactions involving C[sub 4]AF occurs when hemihydrate is the reactant: gypsum formation during the first hour, ettringite formation between 20 and 36 hours, and the conversion of ettringite to monosulfate over a period of about 12 hours. Monosulfate formation initiates prior to the complete consumption of gypsum. The onset of this conversion occurs at a shorter hydration time when hemihydrate is a reactant and the total amount of heat evolved is lower. The hydration reactions in saturated calcium hydroxide solution occur more slowly than those in water. Based on heat liberation, C[sub 4]AF reacts at a much higher rate than C[sub 3]A. Ettringite formation occurs during the first 8 to 9 days of C[sub 3]A hydration. Once the gypsum is consumed, ettringite converts to monosulfate during two additional days. Compared to gypsum, hemihydrate decreases the rates of hydration of both C[sub 3]A and C[sub 4]AF. The effects on the hydration characteristics of C[sub 4]AF are significant. The hydration of C[sub 3]A with gypsum in water, in saturated Ca(OH)[sub 2] solution, and in 0.3M NaOH solution were compared. Heat evolution is the lowest for hydration in 0.3M NaOH. The onset of monosulfate formation occurs prior to the complete reaction between gypsum and C[sub 3]A in the NaOH solution.

  2. The hydration of interstitial Portland cement phases in sodium hydroxide and magnesium sulfate solutions

    Microsoft Academic Search

    Boyd Arthur Clark

    2001-01-01

    Formation of sulfoaluminate compounds was investigated by isothermal calorimetry and X-ray diffraction (XRD). Tricalcium aluminate\\/gypsum mixtures with a molar ratio of 1:1 sulfate-to-aluminate were hydrated at constant temperatures from 30 to 90°C; in de-ionized water, in 200mM and in 500mM sodium hydroxide (NaOH) solutions. Hydration in de-ionized water produced ettringite and monosulfate as the dominant crystalline phases, regardless of temperature.

  3. Potassium bicarbonate, but not sodium bicarbonate, reduces urinary calcium excretion and improves calcium balance in healthy men

    Microsoft Academic Search

    Jacob Lemann; Richard W Gray; Joan A Pleuss

    1989-01-01

    Potassium bicarbonate, but not sodium bicarbonate, reduces urinary calcium excretion and improves calcium balance in healthy men. Previous studies demonstrated that the administration of NaHCO3 or sodium citrate had either only a small effect to reduce urinary Ca excretion or no effect, but that potassium citrate significantly reduced urinary Ca excretion. In order to further evaluate and compare the effects

  4. RLE DES IONS SODIUM DANS L'ABSORPTION GASTRIQUE DU CALCIUM CHEZ LES RUMINANTS

    E-print Network

    Paris-Sud XI, Université de

    RÔLE DES IONS SODIUM DANS L'ABSORPTION GASTRIQUE DU CALCIUM CHEZ LES RUMINANTS D. TIMET D. EMANOVI ABSORPTION OF CALCIUM IN RUMINANTS. - The influence of sodium ions on gastric absorption of calcium in ruminants was studied with regard to the accompanying anions. Bags made of the surviving mucous membrane

  5. Reaction of sodium calcium borate glasses to form hydroxyapatite.

    PubMed

    Han, Xue; Day, Delbert E

    2007-09-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape. PMID:17486301

  6. Aqueous solutions of calcium ions: hydration numbers and the effect of temperature.

    PubMed

    Zavitsas, Andreas A

    2005-11-01

    Hydration numbers of calcium ions are determined from extensive measurements of colligative properties of water solutions of calcium salts. The hydration numbers reported refer to the average number of water molecules that are bound sufficiently strongly to calcium ions so as to be removed from the solvent and become part of the solute. Contrary to common descriptions of deviations from ideal behavior for concentrated solutions, ideal behavior is demonstrated when mole fractions are calculated by taking account of such bound water. Measurements over wide concentration and temperature ranges are used to obtain the effect of temperature on the average hydration number of Ca(2+). Freezing point depression measurements yield a hydration number of 12.0 +/- 0.8. Boiling point elevations yield 6.7 +/- 0.6. Consistent with this, vapor pressure measurements from 0 to 200 degrees C show a gradual decrease in hydration number with increasing temperature, with a value of 5.0 at 200 degrees C. PMID:16853671

  7. Accelerated growth of calcium silicate hydrates: Experiments and simulations

    SciTech Connect

    Nicoleau, Luc, E-mail: luc.nicoleau@basf.com

    2011-12-15

    Despite the usefulness of isothermal calorimetry in cement analytics, without any further computations this brings only little information on the nucleation and growth of hydrates. A model originally developed by Garrault et al. is used in this study in order to simulate hydration curves of cement obtained by calorimetry with different known hardening accelerators. The limited basis set of parameters used in this model, having a physical or chemical significance, is valuable for a better understanding of mechanisms underlying in the acceleration of C-S-H precipitation. Alite hydration in presence of four different types of hardening accelerators was investigated. It is evidenced that each accelerator type plays a specific role on one or several growth parameters and that the model may support the development of new accelerators. Those simulations supported by experimental observations enable us to follow the formation of the C-S-H layer around grains and to extract interesting information on its apparent permeability.

  8. Reaction of sodium calcium borate glasses to form hydroxyapatite

    Microsoft Academic Search

    Xue Han; Delbert E. Day

    2007-01-01

    This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction\\u000a was between either 1CaO · 2Na2O · 6B2O3 or 2CaO · 2Na2O · 6B2O3 glass and a 0.25 M phosphate (K2HPO4) solution at 37, 75 and 200 °C. Glass samples in the form of irregular particles (125–180 ?m) and microspheres (45–90 and\\u000a 125–180 ?m) were used in order to understand the reaction mechanism. The effect

  9. Sodium-calcium exchange influences the response to endothelin-1 in lens epithelium.

    PubMed

    Okafor, Mansim; Tamiya, Shigeo; Delamere, Nicholas A

    2003-09-01

    Studies were conducted to examine the possible involvement of Na+-Ca2+ exchanger in determining the magnitude of the endothelin-1 (ET-1)-receptor-mediated calcium signal in porcine lens epithelial cells. Cytoplasmic calcium concentration was measured in primary cultured cells loaded with Fura-2. ET-1 (100 nM) caused cytoplasmic calcium to increase transiently to approximately 250 nM from a baseline of approximately 65 nM. The calcium increase decayed to a sustained plateau 35-45 nM above the baseline. Both the peak and plateau component of the ET-1 calcium response were abolished by PD145065, an ET receptor antagonist, and by cyclopiazonic acid (CPA) (10 microM). In calcium-free bathing solution, only the plateau was abolished. In the presence of ouabain, low-sodium bathing solution or bepridil, a sodium-calcium exchange inhibitor, peak height more than doubled. Bepridil also increased the peak height of the calcium response to ATP. The half-time for decay of the ET-1 and ATP calcium peak was increased several folds by bepridil, ouabain and low-sodium conditions. Measurements of ionomycin-releasable calcium suggested calcium store size was not increased in bepridil-treated cells. Taken together findings suggest inhibition of sodium-calcium exchange increases the magnitude of the receptor-initiated store-release phase of the ET-1 calcium signaling response as the result of impaired calcium clearance from the cytoplasm. PMID:12887970

  10. Controlling local packing and growth in calcium-silicate-hydrate gels.

    PubMed

    Ioannidou, Katerina; Pellenq, Roland J-M; Del Gado, Emanuela

    2014-02-28

    We investigate the development of gels under out-of-equilibrium conditions, such as calcium-silicate-hydrate (C-S-H) gels that form during cement hydration and are the major factor responsible for cement mechanical strength. We propose a new model and numerical approach to follow the gel formation upon precipitation and aggregation of nano-scale colloidal hydrates, whose effective interactions are consistent with forces measured in experiments at fixed lime concentrations. We use Grand Canonical Monte Carlo to mimic precipitation events during Molecular Dynamics simulations, with their rate corresponding to the hydrate production rate set by the chemical environment. Our results display hydrate precipitation curves that indeed reproduce the acceleration and deceleration regime typically observed in experiments and we are able to correctly capture the effect of lime concentration on the hydration kinetics and the gel morphology. Our analysis of the evolution of the gel morphology indicates that the acceleration is related to the formation of an optimal local crystalline packing that allows for large, elongated aggregates to grow and that is controlled by the underlying thermodynamics. The defects produced during precipitation favor branching and gelation that end up controlling the deceleration. The effects on the mechanical properties of C-S-H gels are also discussed. PMID:24652466

  11. Obsidian hydration profiles measured by sputter-induced optical emission

    Microsoft Academic Search

    I. S. T. Tsong; C. A. Houser; N. A. Yusef; R. F. Messier; W. B. White; J. W. MICHELS

    1978-01-01

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the

  12. Dissolution-precipitation behaviour of ettringite, monosulfate, and calcium silicate hydrate

    Microsoft Academic Search

    Isabel Baur; Peter Keller; Denis Mavrocordatos; Bernhard Wehrli; C. Annette Johnson

    2004-01-01

    The stability of the cement minerals ettringite, monosulfate, and calcium silicate hydrate (C-S-H) was investigated to better understand the uptake of contaminants in waste–cement mixes. Suspensions were spiked with radioisotopes of components (45Ca and 35SO4 for ettringite and monosulfate and 45Ca and 32Si for C-S-H) to observe their uptake behaviour within 0–70 days. A physical model was applied to determine

  13. Atomistic structure of sodium and calcium silicate intergranular films in alumina

    E-print Network

    Garofalini, Stephen H.

    and strong. The Lucalox® process uses MgO as an additive to produce envelopes for sodium vapor lamps.3Atomistic structure of sodium and calcium silicate intergranular films in alumina David A. Litton March 1998; accepted 21 October 1998) Sodium silicate intergranular films (IGF) in contact

  14. Sodium-calcium ion exchange in the weathering of shales: Implications for global weathering budgets

    Microsoft Academic Search

    T. E. Cerling; B. L. Pederson; K. L. Von Damm

    1989-01-01

    Unpolluted rivers and streams that drain marine shales show an excess of sodium compared to chloride and a deficiency of calcium and magnesium compared to sulfate and alkalinity. This is due in part to cation exchange of sodium for divalent cations on clay minerals. Consideration of the global weathering budget suggest that up to 34% of the sodium in the

  15. Influence of crystal hydration on the mechanical properties of sodium naproxen.

    PubMed

    Joiris, Etienne; Di Martino, Piera; Malaj, Ledjan; Censi, Roberta; Barthélémy, Christine; Odou, Pascal

    2008-09-01

    The aim of this work is to establish a correlation between water uptake by anhydrous sodium naproxen (ASN) at two different relative humidities and modifications in tableting and densification behaviour under hydration. Water uptake was evaluated at different relative humidities. Models for the hydration kinetics of ASN at 55% and 86%, corresponding to the formation of the dihydrated and tetrahydrated forms, respectively, were evaluated assuming Eyring's dependence on temperature. Tabletability, compressibility, compactibility, and densification behaviour were determined using an instrumented single punch tablet machine. Kinetic data are consistent with a model where water molecules enter the crystal preferentially along hydrophilic tunnels existing in the crystal structure and corresponding to the propionate side chain. Water inclusion perturbs the crystallographic structure, causing slight structural changes according to the amount and associated to an increase in entropy. The interposition of water molecules between sodium naproxen molecules weakens intermolecular bonds, and these sites can behave like sliding planes under compression. Such structural changes may explain the improved compression behaviour and modified densification propensity mechanism. Kinetic data describing the water hydration mechanism of ASN explain in an original way the improved tableting and densification properties under hydration. PMID:18539444

  16. Structural Basis for Pharmacology of Voltage-Gated Sodium and Calcium Channels.

    PubMed

    Catterall, William A; Swanson, Teresa M

    2015-07-01

    Voltage-gated sodium channels initiate action potentials in nerve, muscle, and other electrically excitable cells. Voltage-gated calcium channels are activated by depolarization during action potentials, and calcium influx through them is the key second messenger of electrical signaling, initiating secretion, contraction, neurotransmission, gene transcription, and many other intracellular processes. Drugs that block sodium channels are used in local anesthesia and the treatment of epilepsy, bipolar disorder, chronic pain, and cardiac arrhythmia. Drugs that block calcium channels are used in the treatment of epilepsy, chronic pain, and cardiovascular disorders, including hypertension, angina pectoris, and cardiac arrhythmia. The principal pore-forming subunits of voltage-gated sodium and calcium channels are structurally related and likely to have evolved from ancestral voltage-gated sodium channels that are widely expressed in prokaryotes. Determination of the structure of a bacterial ancestor of voltage-gated sodium and calcium channels at high resolution now provides a three-dimensional view of the binding sites for drugs acting on sodium and calcium channels. In this minireview, we outline the different classes of sodium and calcium channel drugs, review studies that have identified amino acid residues that are required for their binding and therapeutic actions, and illustrate how the analogs of those key amino acid residues may form drug-binding sites in three-dimensional models derived from bacterial channels. PMID:25848093

  17. Santaclaraite, a new calcium-manganese silicate hydrate from California.

    USGS Publications Warehouse

    Erd, Richard C.; Ohashi, Y.

    1984-01-01

    Santaclaraite, ideally CaMn4(Si5O14(OH))(OH).H2O, occurs as pink and tan veins and masses in Franciscan chert in the Diablo Range, Santa Clara and Stanislaus counties, California. It is associated with four unidentified Mn silicates, Mn-howieite, quartz, braunite, calcite, rhodochrosite, kutnahorite, baryte, harmotome, chalcopyrite and native copper. Santaclaraite is triclinic, space group B1, a 15.633(1), b 7.603(1) , c 12.003(1) A, alpha 109.71(1)o, beta 88.61(1)o, gamma 99.95(1) o, V 1322.0(3) A3; Z = 4. The strongest lines of the X-ray pattern are 7.04(100), 3.003(84), 3.152(80), 7.69(63), 3.847(57) A. Crystals are lamellar to prismatic (flattened on (100)), with good cleavage on (100) and (010); H. 61/2 Dcalc. 3.398 g/cm3, Dmeas. 3.31 (+ or -0.01); optically biaxial negative, alpha 1.681, beta 1.696, gamma 1.708 (all + or - 0.002), 2Valpha 83 (+ or -1)o. Although chemically a hydrated rhodonite, santaclaraite dehydrates to Mn-bustamite at approx 550oC (in air) . Santaclaraite is a five-tetrahedral-repeat single-chain silicate and has structural affinities with rhodonite, nambulite, marsturite, babingtonite and inesite.-J.A.Z.

  18. Obsidian hydration profiles measured by sputter-induced optical emission.

    PubMed

    Tsong, I S; Houser, C A; Yusef, N A; Messier, R F; White, W B; Michels, J W

    1978-07-28

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the phenomena underlying the obsidian hydration dating technique. PMID:17793728

  19. Composition and density of nanoscale calcium?silicate?hydrate in cement

    SciTech Connect

    Allen, Andrew J.; Thomas, Jeffrey J.; Jennings, Hamlin M. (NIST); (NWU)

    2009-08-26

    Although Portland cement concrete is the world's most widely used manufactured material, basic questions persist regarding its internal structure and water content, and their effect on concrete behaviour. Here, for the first time without recourse to drying methods, we measure the composition and solid density of the principal binding reaction product of cement hydration, calcium-silicate-hydrate (C-S-H) gel, one of the most complex of all gels. We also quantify a nanoscale calcium hydroxide phase that coexists with C-S-H gel. By combining small-angle neutron and X-ray scattering data, and by exploiting the hydrogen/deuterium neutron isotope effect both in water and methanol, we determine the mean formula and mass density of the nanoscale C-S-H gel particles in hydrating cement. We show that the formula, (CaO){sub 1.7}(SiO{sub 2})(H{sub 2}O){sub 1.80}, and density, 2.604 Mg m{sup -3}, differ from previous values for C-S-H gel, associated with specific drying conditions. Whereas previous studies have classified water within C-S-H gel by how tightly it is bound, in this study we classify water by its location - with implications for defining the chemically active (C-S-H) surface area within cement, and for predicting concrete properties.

  20. The coexistence of geopolymeric gel and calcium silicate hydrate at the early stage of alkaline activation

    SciTech Connect

    Yip, C.K. [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Lukey, G.C. [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Deventer, J.S.J. van [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia)]. E-mail: jannie@unimelb.edu.au

    2005-09-01

    Scanning electron microscopy was used to study the effects of the addition of ground granulated blast furnace slag (GGBFS) on the microstructure and mechanical properties of metakaolin (MK) based geopolymers. It was found that it is possible to have geopolymeric gel and calcium silicate hydrate (CSH) gel forming simultaneously within a single binder. The coexistence of these two phases is dependent on the alkalinity of the alkali activator and the MK / GGBFS mass ratio. It has been found that the formation of CSH gel together with the geopolymeric gel occurs only in a system at low alkalinity. In the presence of high concentrations of NaOH (> 7.5 M), the geopolymeric gel is the predominant phase formed with small calcium precipitates scattered within the binder. The coexistence of the two phases is not observed unless a substantial amount of a reactive calcium source is present initially. It is thought that voids and pores within the geopolymeric binder become filled with the CSH gel. This helps to bridge the gaps between the different hydrated phases and unreacted particles; thereby resulting in the observed increase in mechanical strength for these binders.

  1. Changes in the solid state of anhydrous and hydrated forms of sodium naproxen under different grinding and environmental conditions: Evidence of the formation of new hydrated forms.

    PubMed

    Censi, Roberta; Rascioni, Riccardo; Di Martino, Piera

    2015-05-01

    The aim of the present work was to investigate the solid state change of the anhydrous and hydrate solid forms of sodium naproxen under different grinding and environmental conditions. Grinding was carried out manually in a mortar under the following conditions: at room temperature under air atmosphere (Method A), in the presence of liquid nitrogen under air atmosphere (Method B), at room temperature under nitrogen atmosphere (Method C), and in the presence of liquid nitrogen under nitrogen atmosphere (Method D). Among the hydrates, the following forms were used: a dihydrate form (DSN) obtained by exposing the anhydrous form at 55% RH; a dihydrate form (CSN) obtained by crystallizing sodium naproxen from water; the tetrahydrate form (TSN) obtained by exposing the anhydrous form at 75% RH. The metastable monohydrate form (MSN), previously described in the literature, was not used because of its high physical instability. The chemical stability during grinding was firstly assessed and proven by HPLC. Modification of the particle size and shape, and changes in the solid state under different grinding methods were evaluated by scanning electron microscopy, and X-ray powder diffractometry and thermogravimetry, respectively. The study demonstrated the strong influence of starting form, grinding and environmental conditions on particle size, shape and solid state of recovered sodium naproxen forms. In particular, it was demonstrated that in the absence of liquid nitrogen (Methods A and C), either at air or at nitrogen atmosphere, the monohydrate form (MSN) was obtained from any hydrates, meaning that these grinding conditions favored the dehydration of superior hydrates. The grinding process carried out in the presence of liquid nitrogen (Method B) led to further hydration of the starting materials: new hydrate forms were identified as one pentahydrate form and one hexahydrate form. The hydration was caused by the condensation of the atmospheric water on sodium naproxen particles by liquid nitrogen and by the grinding forces that created a close contact between water and drug. The simultaneous disruption of the crystals, occurring during grinding, and their close contact with water molecules promoted the conversion in higher hydrates. Under the Method D, it was possible to highlight a certain tendency to hydration probably due to a rearrangement of water already present into the hydrates, but results were substantially different from Method B. Thus, summarizing, the different SN forms behave differently under different grinding and environmental conditions. PMID:25796350

  2. Spontaneous supersaturation of calcium D-gluconate during isothermal dissolution of calcium L-lactate in aqueous sodium D-gluconate.

    PubMed

    Vavrusova, Martina; Skibsted, Leif H

    2014-01-01

    Continuing dissolution of solid calcium L-lactate pentahydrate in saturated aqueous solutions following addition of solid sodium D-gluconate corresponding to a gluconate/lactate ratio around three was found to result in homogeneous solutions supersaturated with calcium D-gluconate by a factor of seven, from which calcium D-gluconate monohydrate precipitated only slowly. In contrast, dissolution of calcium D-gluconate monohydrate by sodium L-lactate in aqueous solution with the reverse lactate/gluconate ratio also around three did not result in similar homogeneous solutions on the route to solid calcium L-lactate pentahydrate. This increasing supersaturation of calcium D-gluconate during dissolution of calcium L-lactate in aqueous sodium D-gluconate may enhance calcium bioavailability. The dissolution overshooting depends on competitive kinetics and is also of interest in modeling biomineralization and in designing novel food products with increased calcium bioavailability. PMID:24281051

  3. Synergistic fire retardancy of colemanite, a natural hydrated calcium borate, in high-impact polystyrene containing brominated epoxy and antimony oxide

    Microsoft Academic Search

    Cevdet Kaynak; Nihat Ali Isitman

    2011-01-01

    This study explores for the first time the synergistic fire retardant action of natural hydrated calcium borate, namely the mineral colemanite, which partially replaces antimony oxide in brominated flame retardant high-impact polystyrene compounds. Various antimony oxide to hydrated calcium borate ratios were employed keeping the brominated flame retardant additive at a constant loading level. With partial colemanite substitution for antimony

  4. Calcium-aluminum-silicate-hydrate “cement” phases and rare Ca-zeolite association at Colle Fabbri, Central Italy

    Microsoft Academic Search

    Francesco Stoppa; Fernando Scordari; Ernesto Mesto; Victor V. Sharygin; Giorgio Bortolozzi

    2010-01-01

    Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite\\u000a metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization\\u000a several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate\\u000a (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) — “cement” phases - i.e., thaumasite,

  5. Crystal growth of calcium carbonate in silk fibroin/sodium alginate hydrogel

    NASA Astrophysics Data System (ADS)

    Ming, Jinfa; Zuo, Baoqi

    2014-01-01

    As known, silk fibroin-like protein plays a pivotal role during the formation of calcium carbonate (CaCO3) crystals in the nacre sheets. Here, we have prepared silk fibroin/sodium alginate nanofiber hydrogels to serve as templates for calcium carbonate mineralization. In this experiment, we report an interesting finding of calcium carbonate crystal growth in the silk fibroin/sodium alginate nanofiber hydrogels by the vapor diffusion method. The experimental results indicate calcium carbonate crystals obtained from nanofiber hydrogels with different proportions of silk fibroin/sodium alginate are mixture of calcite and vaterite with unusual morphologies. Time-dependent growth study was carried out to investigate the crystallization process. It is believed that nanofiber hydrogels play an important role in the process of crystallization. This study would help in understanding the function of organic polymers in natural mineralization, and provide a novel pathway in the design and synthesis of new materials related unique morphology and structure.

  6. Effects of anesthetics pentobarbital sodium and chloral hydrate on urine proteome

    PubMed Central

    Zhao, Mindi; Li, Xundou; Li, Menglin

    2015-01-01

    Urine can be a better source than blood for biomarker discovery since it accumulates many changes. The urine proteome is susceptible to many factors, including anesthesia. Pentobarbital sodium and chloral hydrate are commonly used anesthetics in animal experiments. This study demonstrated the effects of these two anesthetics on the rat urine proteome using liquid chromatography–tandem mass spectrometry (LC-MS/MS). With anesthesia, the urinary protein-to-creatinine ratio of all rats increased twofold. The relative abundance of 22 and 23 urinary proteins were changed with pentobarbital sodium or chloral hydrate anesthesia, respectively, as determined by label-free quantification. Among these changed proteins, fifteen had been considered as candidate biomarkers such as uromodulin, and sixteen had been considered stable in healthy human urine, which are more likely to be considered as potential biomarkers when changed, such as transferrin. The pattern of changed urinary proteins provides clues to the discovery of urinary proteins regulatory mechanisms. When determining a candidate biomarker, anesthetic-related effects can be excluded from future biomarker discovery studies. Since anesthetics take effects via nervous system, this study is the first to provide clues that the protein handling function of the kidney may possibly be regulated by the nervous system. PMID:25789206

  7. Acidosis and hypercalciuria: renal mechanisms affecting calcium, magnesium and sodium excretion in the sheep

    PubMed Central

    Stacy, B. D.; Wilson, B. W.

    1970-01-01

    1. Observations were made on the excretion of calcium and magnesium by the sheep's kidney following manipulation of the acid—base status. 2. Intravascular administration of a synthetic solution resembling saliva abolished the naturally occurring acidosis in sheep during feeding, and it also prevented the normal onset of post-prandial hypercalciuria and hypermagnesiuria. 3. Non-respiratory acidosis (induced by infusion of hydrochloric acid) and respiratory acidosis arising from inhalation of 6% (v/v) CO2 in air both caused an acute increase in calcium excretion. 4. Measurement of filtered loads showed that feeding exerted an effect on the functional characteristics of the sheep's kidney. The renal clearances of calcium and magnesium increased, whereas sodium clearance decreased. 5. Experimental conditions were arranged so that variations in acid—base status could be imposed at a time when the filtered load of calcium was declining. 6. With hydrochloric acid-acidosis the renal excretion of calcium increased, despite a steady fall in the filtered load. With sodium bicarbonate alkalosis, the filtered load and the renal excretion of calcium decreased in unison. 7. These variations in calcium excretion were not accompanied by corresponding changes in the excretion of sodium. 8. It is concluded that the renal tubules in the sheep are sensitive to acid—base status and that they respond to a lowering of the blood pH by decreasing the tubular reabsorption of filtered calcium. PMID:5499811

  8. Novel technique for phosphorus recovery from aqueous solutions using amorphous calcium silicate hydrates (A-CSHs).

    PubMed

    Okano, Kenji; Uemoto, Masahide; Kagami, Jumpei; Miura, Keiichi; Aketo, Tsuyoshi; Toda, Masaya; Honda, Kohsuke; Ohtake, Hisao

    2013-05-01

    A novel technique for phosphorus (P) recovery from aqueous solutions was developed using amorphous calcium silicate hydrates (A-CSHs). A-CSHs, which have a high Ca/Si molar ratio of 2.0 or greater, could be synthesized using unlimitedly available, inexpensive materials such as siliceous shale and calcium hydroxide. A-CSHs showed high performance for P recovery from an anaerobic sludge digestion liquor (ASDL) and the synthetic model liquor (s-ASDL) containing 89 mg PO4-P/L. After 20 min mixing, 1.5 g/L A-CSHs could remove approximately 69 and 73% PO4-P from ASDL and s-ASDL, respectively. By contrast, autoclaved lightweight concrete particles, which contained crystalline calcium silicate hydrates as a principal component, removed only 10 and 6% PO4-P from ASDL and s-ASDL, respectively, under the same experimental conditions. When A-CSHs were washed with deionized water to remove free Ca(OH)2, P removability was significantly improved (up to 82%) despite the reduction in the amount of Ca(2+) released. Unlike in the case of Ca(OH)2, no significant carbonate inhibition was observed with P removal by A-CSHs. Moreover, P removed by A-CSHs showed better settleability, filterability, and dewaterability than P precipitated with conventional CaCl2 and Ca(OH)2. The present study demonstrated that A-CSHs have great potential as a novel, beneficial material for P recovery and recycling. PMID:23497975

  9. Characterization of white Portland cement hydration and the C-S-H structure in the presence of sodium aluminate by {sup 27}Al and {sup 29}Si MAS NMR spectroscopy

    SciTech Connect

    Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Joergen

    2004-05-01

    The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium aluminate (NaAlO{sub 2}) at 5 and 20 deg. C are investigated by {sup 27}Al and {sup 29}Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO{sub 2} accelerates the hydration of alite and belite and results in calcium-silicate-hydrate (C-S-H) phases with longer average chain lengths of SiO{sub 4}/AlO{sub 4} tetrahedra. The C-S-H phases are investigated in detail and it is shown that the Al/Si ratio for the chains of tetrahedra is quite constant during the time studied for the hydration (6 h to 2 years) but increases for higher concentration of the NaAlO{sub 2} solution. The average chain lengths of 'pure' silicate and SiO{sub 4}/AlO{sub 4} tetrahedra demonstrate that Al acts as a linker for the silicate chains, thereby producing aluminosilicate chains with longer average chain lengths. Finally, it is shown that NaAlO{sub 2} reduces the quantity of ettringite and results in larger quantities of monosulfate and a calcium aluminate hydrate phase.

  10. Selective removal of radio-sodium from neutron-activated materials by retention on hydrated antimony pentoxide

    Microsoft Academic Search

    F. Girardi; E. Sabbioni

    1968-01-01

    A new method is presented to remove sodium interferences from neutron-activated materials. The method is based on passage\\u000a of the samples, dissolved in a concentrated acid solution on a column of hydrated antimony pentoxide (HAP). The retention\\u000a is quantitative with a maximum capacity of 31 mg Na\\/g HAP. Only tantalum, in addition to sodium, was retained by HAP out of

  11. Effect of sodium and calcium ingestion on thermoregulation during exercise in man

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Brock, P. J.; Morse, J. T.; Van Beaumont, W.; Montgomery, L. D.; Convertino, V. A.; Mangseth, G. R.

    1978-01-01

    The effects of hypertonic sodium and calcium ingestion on body temperature during exercise in cool and hot environments are investigated. Rectal and mean skin temperatures, sweat rates and arm and leg total blood flows were measured in men during periods of rest, submaximal exercise and recovery at temperatures of 26.5 C and 39.4 C after ingestion of NaCl and CaCl2 solutions. In both environments, higher rectal temperatures are observed after hypertonic sodium ingestion, which is also associated with attenuated blood flow in the extremities, lower sweat rates and slightly higher skin temperature in the heat, indicating significant thermoregulatory responses. Hypertonic calcium and isotonic sodium cause no temperature change, although calcium caused a reduction of blood flow in the extremities.

  12. [Monitoring of formation of diclofenac sodium salt hydrates and their influence on the drug dissolution from prepared tablets].

    PubMed

    Doležel, Petr; Muselík, Jan; Králová, Michaela; Vetchý, David

    2013-12-01

    NIR spectroscopy together with multivariate data analysis were used to analyze the hydrates of diclofenac sodium prepared from the non-aqueous solvents tetrahydrofuran and methanol under standard laboratory conditions at 20 °C and relative humidity less than 60%. It was confirmed that the developed PLS regression model can monitor the process of formation of hydrates. It was also found that the hydrated form of diclofenac sodium arises during the preparation of the dosage form the using technology of impregnating the solid carrier by non-aqueous solvents, which resulted in reducing of the drug release rate from prepared tablets up to twice. NIR spectroscopy was confirmed as one of the effective PAT (Process Analytical Technology) methods. PMID:24393114

  13. Influences of additives on the gas hydrate cool storage process in a new gas hydrate cool storage system

    Microsoft Academic Search

    Yuehong Bi; Tingwei Guo; Tingying Zhu; Liang Zhang; Lingen Chen

    2006-01-01

    Experimental research on the crystallization process of the gas hydrate HCFC141b is performed for this paper. The influences of different proportions of calcium hypochlorite or benzenesulfonic acid sodium salt on the crystallization process are studied. The results show that the degree of subcooling of formation is obviously decreased, and the formation rate of the gas hydrate is greatly accelerated by

  14. Fracture toughness of calcium–silicate–hydrate from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Bauchy, M.; Laubie, H.; Abdolhosseini Qomi, M. J.; Hoover, C. G.; Ulm, F.-J.; Pellenq, R. J.-M.

    2015-07-01

    Cement is the most widely used manufacturing material in the world and improving its toughness would allow for the design of slender infrastructure, requiring less material. To this end, we investigate by means of molecular dynamics simulations the fracture of calcium-silicate-hydrate (C-S-H), the binding phase of cement, responsible for its mechanical properties. For the first time, we report values of the fracture toughness, critical energy release rate, and surface energy of C-S-H grains. This allows us to discuss the brittleness of the material at the atomic scale. We show that, at this scale, C-S-H breaks in a ductile way, which prevents from using methods based on linear elastic fracture mechanics. Knowledge of the fracture properties of C-S-H at the nanoscale opens the way for an upscaling approach to the design of tougher cement.

  15. Hydrothermal Formation Of Hemi-hydrate Calcium Sulfate Whiskers In The Presence Of Additives

    NASA Astrophysics Data System (ADS)

    Luo, K. B.; Li, C. M.; Xiang, L.; Li, H. P.; Ning, P.

    2010-11-01

    The influence of addictives on the hydrothermal formation of hemi-hydrate calcium sulfate (CaSO4?0.5H2O) whiskers were discussed in this paper, using CaCl2 and Na2SO4 as the reactants. The presence of NaCl, CaCl2 or Na2SO4 increased the concentrations of Ca2+ and SO42-, leading to the formation of CaSO4?0.5H2O whiskers with aspect ratio lower than 50. The one dimensional growth of CaSO4?0.5H2O whiskers was enhanced in water with no additives owing to the low super-saturation, leading to the formation of uniform whiskers with a length of 200-2000 ?m and an aspect ratio higher than 100.

  16. Fractionation and solubility of cadmium in paddy soils amended with porous hydrated calcium silicate.

    PubMed

    Zhao, Xiu-Lan; Masaihiko, Saigusa

    2007-01-01

    Previous studies have shown that porous hydrated calcium silicate (PS) is very effective in decreasing cadmium (Cd) content in brown rice. However, it is unclear whether the PS influences cadmium transformation in soil. The present study examined the effect of PS on pH, cadmium transformation and cadmium solubility in Andosol and Alluvial soil, and also compared its effects with CaCO3, acidic porous hydrated calcium silicate (APS) and silica gel. Soil cadmium was operationally fractionationed into exchangeable (Exch), bound to carbonates (Carb), bound to iron and manganese oxides (FeMnO(x)), bound to organic matters (OM) and residual (Res) fraction. Application of PS and CaCO3 at hig rates enhanced soil pH, while APS and silica gel did not obviously change soil pH. PS and CaCO3 also increased the FeMnO(x)-Cd in Andosol and Carb-Cd in Alluvial soil, thus reducing the Exch-Cd in the tested soils. However, PS was less effective than CaCO3 at the same application rate. Cadmium fractions in the two soils were not changed by the treatments of APS and silica gel. There were no obvious differences in the solubility of cadmium in soils treated with PS, APS, silica gel and CaCO3 except Andosol treated 2.0% CaCO3 at the same pH of soil-CaCl2 suspensions. These findings suggested that the decrease of cadmium availability in soil was mainly attributed to the increase of soil pH caused by PS. PMID:17918598

  17. Calcium reduces the sodium permeability of luminal membrane vesicles from toad bladder. Studies using a fast-reaction apparatus

    SciTech Connect

    Chase, H.S. Jr.; Al-Awqati, Q.

    1983-05-01

    Regulation of the sodium permeability of the luminal membrane is the major mechanism by which the net rate of sodium transport across tight epithelia is varied. Previous evidence has suggested that the permeability of the luminal membrane might be regulated by changes in intracellular sodium or calcium activities. To test this directly, we isolated a fraction of the plasma membrane from the toad urinary bladder, which contains a fast, amiloride-sensitive sodium flux with characteristics similar to those of the native luminal membrane. Using a flow-quench apparatus to measure the initial rate of sodium efflux from these vesicles in the millisecond time range, we have demonstrated that the isotope exchange permeability of these vesicles is very sensitive to calcium. Calcium reduces the sodium permeability, and the half-maximal inhibitory concentration is 0.5 microM, well within the range of calcium activity found in cells. Also, the permeability of the luminal membrane vesicles is little affected by the ambient sodium concentration. These results, when taken together with studies on whole tissue, suggest that cell calcium may be an important regulator of transepithelial sodium transport by its effect on luminal sodium permeability. The effect of cell sodium on permeability may be mediated by calcium rather than by sodium itself.

  18. Distribution of magnesium, calcium, sodium and potassium in tissues of the hip joint.

    PubMed

    Brodziak-Dopiera?a, Barbara; Kwapuli?ski, Jerzy; Sobczyk, Krzysztof; Wiechu?a, Danuta

    2013-01-01

    The aim of this study was to determine the distribution of magnesium, calcium, sodium and potassium in tissues of the hip joint and to look for any correlations between these minerals. The study was performed using hip joint samples taken from people living in the Upper Silesian Industrial Region in Poland. Ninety one subjects, 66 women and 25 men, were included in this study. The samples were obtained intra-operatively during hip joint replacement procedures. The concentrations of magnesium, calcium, sodium and potassium were measured by atomic absorption spectrophotometry (AAS). Our results showed that these minerals are most abundant in the cancellous bone of the hip joint. They were found next more abundantly in the cortical bone and the cancellous bone from the intertrochanteric area. Levels of magnesium, potassium and calcium were lower in articular cartilage compared with other parts of the hip joint; however, sodium levels were at their highest in this tissue. The lowest levels of these minerals were found in the articular capsule. Those patients with fractures of the femoral neck had lower levels of magnesium, potassium, and calcium, but higher levels of sodium compared with the group with degenerative changes. We can also confirm that in the population studied, calcium levels in cancellous bone of the head of the femur decreased with age. PMID:24153328

  19. Immobilization of Pseudomonas sp. DG17 onto sodium alginate–attapulgite–calcium carbonate

    PubMed Central

    Wang, Hong Qi; Hua, Fei; Zhao, Yi Cun; Li, Yi; Wang, Xuan

    2014-01-01

    A strain of Pseudomonas sp. DG17, capable of degrading crude oil, was immobilized in sodium alginate–attapulgite–calcium carbonate for biodegradation of crude oil contaminated soil. In this work, proportion of independent variables, the laboratory immobilization parameters, the micromorphology and internal structure of the immobilized granule, as well as the crude oil biodegradation by sodium alginate–attapulgite–calcium carbonate immobilized cells and sodium alginate–attapulgite immobilized cells were studied to build the optimal immobilization carrier and granule-forming method. The results showed that the optimal concentrations of sodium alginate–attapulgite–calcium carbonate and calcium chloride were 2.5%–3.5%, 0.5%–1%, 3%–7% and 2%–4%, respectively. Meanwhile, the optimal bath temperature, embedding cell amount, reaction time and multiplication time were 50–60 °C, 2%, 18 h and 48 h, respectively. Moreover, biodegradation was enhanced by immobilized cells with a total petroleum hydrocarbon removal ranging from 33.56% ± 3.84% to 56.82% ± 3.26% after 20 days. The SEM results indicated that adding calcium carbonate was helpful to form internal honeycomb-like pores in the immobilized granules. PMID:26019567

  20. Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines

    SciTech Connect

    Rebak, R B; Ilevbare, G O; Carranza, R M

    2007-08-11

    A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.

  1. Thermodynamic behaviour of sodium and calcium based sorbents in the emission control of waste incinerators.

    PubMed

    Verdone, Nicola; De Filippis, Paolo

    2004-02-01

    The dry treatment of flue gas produced by incineration processes is discussed thermodynamically. The study investigates the theoretical limits achieved by sodium and calcium based sorbents in the removal of the pollutant species HCl, NOx and SO2. Calculations were performed varying the temperature and the molar ratio between the amount of the injected alkaline sorbent and the content of the pollutant gaseous species in the flue gas. Results show that sodium cation based sorbents are more efficient than calcium based ones in the whole investigated temperature range (100-600 degrees C). The higher effectiveness of sodium based sorbents is particularly remarkable towards hydrogen chloride, whose concentration can always be reduced below the values set by the environmental regulations. Possible improvements in the treatment efficiency of combustion fumes obtainable with sodium based sorbents can be mainly summarised in a lower concentration of HCl in the treated gas and in a partial reduction of NOx concentration. PMID:14637355

  2. Formation of hydroxyapatite in soils using calcium citrate and sodium phosphate for control of strontium migration.

    SciTech Connect

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Sanchez, Charles Anthony (University of Arizona, Yuma, AZ); Zhao, Hongting; Salas, Fred Manuel; Hasan, Mahmoud A. (Egyptian Atomic Energy Authority, Cairo, Egypt); Holt, Kathleen Caroline

    2003-08-01

    {sup 90}Sr contamination is a major problem at several U.S. sites. At some sites, {sup 90}Sr has migrated deep underground making site remediation difficult. In this paper, we describe a novel method for precipitation of hydroxyapatite, a strong sorbent for {sup 90}Sr, in soil. The method is based on mixing a solution of calcium citrate and sodium phosphate in soil. As the indigenous soil microorganisms mineralize the citrate, the calcium is released and forms hydroxyapatite. Soil, taken from the Albuquerque desert, was treated with a sodium phosphate solution or a sodium phosphate/calcium citrate solution. TEM and EDS were used to identify hydroxyapatite with CO{sub 3}{sup 2-} substitutions, with a formula of (Ca{sub 4.8}Na{sub 0.2})[(PO{sub 4}){sub 2.8}(CO{sub 3}){sub 0.2}](OH), in the soil treated with the sodium phosphate/calcium citrate solution. Untreated and treated soils were used in batch sorption experiments for Sr uptake. Average Sr uptake was 19.5, 77.0 and 94.7% for the untreated soil, soil treated with sodium phosphate, and soil with apatite, respectively. In desorption experiments, the untreated soil, phosphate treated soil and apatite treated soil released an average of 34.2, 28.8 and 4.8% respectively. The results indicate the potential of forming apatite in soil using soluble reagents for retardation of radionuclide migration.

  3. Dietary Sodium Effects on Bone Loss and Calcium Metabolism During Bed Rest

    NASA Technical Reports Server (NTRS)

    Smith, Scott M.; Arnaud, Sara B.; Abrams, Steven A.; Paloski, W. H. (Technical Monitor)

    2000-01-01

    The acceleration of age-related bone loss is one of the most detrimental effects of space flight. The ability to understand and counteract this loss will be critical for crew health and safety during and after long-duration missions. Studies in healthy ambulatory individuals have linked high salt (sodium) diets, hypercalciuria, and increased renal stone risk. Dietary salt may modulate bone loss through changes in calcium metabolism and the calcium endocrine system. The research proposed here will determine the role of dietary salt in the loss of bone during simulated space flight. Calcium metabolism will be determined through calcium kinetics studies, endocrine and biochemical measurements; and estimates of the mass, distribution and mechanical properties of bone, in subjects fed low (100 mmol sodium/day) or high (250 mmol sodium/day) levels of dietary salt during 28 days of headdown tilt bedrest. This research addresses the role of dietary salt in the loss of bone and calcium in space flight, and integrates the changes in calcium metabolism with those occurring in other physiologic systems. These data will be critical for both countermeasure development, and in determination of nutritional requirements for extended-duration space flight. The potential countermeasures resulting from this research will reduce health risks due to acceleration of age-related osteoporosis and increased risk of renal stone formation..

  4. The DASH Diet and Sodium Reduction Improve Markers of Bone Turnover and Calcium Metabolism in Adults1,2

    Microsoft Academic Search

    Pao-Hwa Lin; Fiona Ginty; Lawrence J. Appel; Mikel Aickin; Arline Bohannon; Patrick Garnero; Denis Barclay; Laura P. Svetkey

    Dietary strategies to prevent and treat osteoporosis focus on increased intake of calcium and vitamin D. Modification of whole dietary patterns and sodium reduction may also be effective. We examined the effects of two dietary patterns and three sodium levels on bone and calcium metabolism in a randomized feeding study. A total of 186 adults, aged 23-76 y, participated. After

  5. Effect of Sodium Fluoride on Calcium Metabolism of Human Beings

    Microsoft Academic Search

    Clayton Rich; John Ensinck

    1961-01-01

    ALTHOUGH bones of human subjects become abnormally dense after several years of industrial exposure to fluorides1,2, no work on the effect of fluoride on calcium balance of human beings has been carried out. Roholm1 and others2 have shown that the severity of skeletal changes is correlated approximately with the extent and duration of exposure to fluoride : moderate exposure resulting

  6. Fermentation of cucumbers brined with calcium chloride instead of sodium chloride

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Generation of waste water containing sodium chloride from cucumber fermentation tank yards could be eliminated if cucumbers were fermented in brines that did not contain this salt. To determine if this is feasible, cucumbers were fermented in brines that contained only calcium chloride to maintain f...

  7. Parabrachial lesions in rats disrupt sodium appetite induced by furosemide but not by calcium deprivation.

    PubMed

    Grigson, P S; Colechio, E M; Power, M L; Schulkin, J; Norgren, R

    2015-03-01

    An appetite for CaCl2 and NaCl occurs in young rats after they are fed a diet lacking Ca or Na, respectively. Bilateral lesions of the parabrachial nuclei (PBN) disrupt normal taste aversion learning and essentially eliminate the expression of sodium appetite. Here we tested whether similar lesions of the PBN would disrupt the calcium-deprivation-induced appetite for CaCl2 or NaCl. Controls and rats with PBN lesions failed to exhibit a calcium-deprivation-induced appetite for CaCl2. Nevertheless, both groups did exhibit a significant calcium-deprivation-induced appetite for 0.5M NaCl. Thus, while damage to the second central gustatory relay in the PBN disrupts the appetite for 0.5M NaCl induced by furosemide, deoxycorticosterone acetate, and polyethylene glycol, the sodium appetite induced by dietary CaCl2 depletion remains intact. PMID:25540931

  8. Calcium-Silicate-Hydrate in cementitious systems : chemomechanical correlations, extreme temperature behavior, and kinetics and morphology of in-situ formation

    E-print Network

    Jagannathan, Deepak

    2013-01-01

    Concrete, the second most used material on the planet, is a multi-scale heterogeneous material. A fundamental component known as Calcium-Silicate-Hydrate which forms from the reaction between cement and water is the binding ...

  9. Effects of Dietary Sodium Bicarbonate and Calcium Chloride on Physiological Responses of Lactating Dairy Cows in Hot Weather

    Microsoft Academic Search

    A. Escobosa; C. E. Coppock; L. D. Rowe Jr; W. L. Jenkins; C. E. Gates

    1984-01-01

    Twenty-four lactating cows were as- signed randomly to three treatments to evaluate responses to large differences of dietary sodium and chloride. Treatments were corn-cottonseed meal-corn silage based complete rations with either: 1) .23% sodium chloride (control), 2) control plus 2.28% calcium chloride, or 3) control plus 1.70% sodium bicarbonate.

  10. Calcium reduces the sodium permeability of luminal membrane vesicles from toad bladder. Studies using a fast-reaction apparatus

    Microsoft Academic Search

    HERBERT S. CHASE; Q. Al-Awqati

    1983-01-01

    Regulation of the sodium permeability of the luminal membrane is the major mechanism by which the net rate of sodium transport across tight epithelia is varied. Previous evidence has suggested that the permeability of the luminal membrane might be regulated by changes in intracellular sodium or calcium activities. To test this directly, we isolated a fraction of the plasma membrane

  11. [Sodium, potassium and calcium content in regional dishes consumed in Sonora, Mexico].

    PubMed

    Grijalva Haro, M I; Valencia, M E; Wyatt, J

    1990-06-01

    The content of sodium, potassium and calcium was determined in 15 regional dishes, by atomic absorption spectrophotometry. The Na:K ratio was high in most of the dishes due to the high sodium content and low content of potassium found. The higher sources of the studied minerals were "tortilla de harina" with 1,372.8 mg/100 g of sodium; "chorizo con papas" with 466 mg/100 g of potassium, and "calabacitas con queso" with 244.1 mg/100 g of calcium. Two of the dishes considered as desserts, "capirotada" and "arroz con leche" showed the lowest Na:K ratio (0.66 and 0.81, respectively). PMID:2133188

  12. A clinical study of the effect of calcium sodium phosphosilicate on dentin hypersensitivity

    PubMed Central

    Surve, Sai M.; Thakur, Srinath L.

    2013-01-01

    Objective: Dentinal hypersensitivity is a commonly encountered problem with varied treatment options for its management. A large number of home use products have been tested and used for the management of dentinal hypersensitivity. This 8 week clinical trial investigates the temporal efficacy of commercially available calcium sodium phosphosilicate containing toothpaste in comparison to a potassium nitrate containing toothpaste. Methods: A total 20 subjects between the ages of 18 to 65 years were screened for a visual analogue score (VAS) for sensitivity of 5 or more by testing with a cold stimulus and randomly divided into test and positive control groups. Baseline sensitivity VAS scores to air evaporative stimulus were recorded for minimum two teeth. The subjects were prescribed respective dentifrices and revaluated for sensitivity scores at 2, 4 and 8 weeks. Results:The study demonstrated reduction in symptoms for all treatment groups from baseline to 2, 4 and 8 weeks. The calcium sodium phosphosilicate group showed a higher degree of effectiveness at reducing hypersensitivity to air evaporative stimulus at 2 weeks, than commercially available potassium nitrate. However, there was no significant difference in scores of subjects using the calcium sodium phosphosilicate toothpaste as compared to potassium nitrate at 4 weeks and 8 weeks. Conclusion: Calcium sodium phosphosilicate showed greater reduction in sensitivity compared to potassium nitrate at an earlier stage which is of high clinical value. However, based on the findings of the present study long term effects of calcium sodium phosphosilicate seem to be less promising than previously claimed. Key words:Dentinal desensitizing agents, dentinal hypersensitivity, toothpaste, pain measurement. PMID:24455046

  13. Calcium-aluminum-silicate-hydrate "cement" phases and rare Ca-zeolite association at Colle Fabbri, Central Italy

    NASA Astrophysics Data System (ADS)

    Stoppa, F.; Scordari, F.; Mesto, E.; Sharygin, V.; Bortolozzi, G.

    2010-06-01

    Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) — "cement" phases - i.e., thaumasite, strätlingite and an ettringite-like phase and several different species of zeolites: chabazite-Ca, willhendersonite, gismon-dine, three phases bearing Ca with the same or perhaps lower symmetry of phillipsite-Ca, levyne-Ca and the Ca-rich analogue of merlinoite. In addition, apophyllite-(KF) and/or apophyllite-(KOH), Ca-Ba-carbonates, portlandite and sulphates were present. A new polymorph from the pyrrhotite group, containing three layers of sphalerite-type structure in the unit cell, is reported for the first time. Such a complex association is unique. Most of these minerals are specifically related to hydration processes of: (1) pyrometamorphic metacarbonate/metapelitic rocks (natural analogues of cement clinkers); (2) mineralization between intrusive stocks and slates; and (3) high-calcium, alkaline igneous rocks such as melilitites and foidites as well as carbonatites. The Colle Fabbri outcrop offers an opportunity to study in situ complex crystalline overgrowth and specific crystal chemistry in mineral phases formed in igneous to hydrothermal conditions.

  14. Improved cycling performance of P2-type layered sodium cobalt oxide by calcium substitution

    NASA Astrophysics Data System (ADS)

    Matsui, Masaki; Mizukoshi, Fumikazu; Imanishi, Nobuyuki

    2015-04-01

    P2-type Na2/3-xCaxCoO2 is synthesized via a conventional solid-state reaction. The substituted calcium ions occupy the sodium ion layer and eliminate the lattice mismatches of the two phases in Na2/3-xCaxCoO2. Several voltage steps typically observed in the voltage profiles of NaxCoO2 are mostly disappeared associated with the expansion of single-phase regions, because the substituted calcium ions hinder the ordering of sodium ions and vacancies. Furthermore the Na2/3-xCaxCoO2 shows improved cycling performance especially at high charging-discharging rate. During the cycling test, the calcium-free Na0.74CoO2 shows phase separation to form an inactive sodium poor phase, while the Na5/8Ca1/24CoO2 maintained the single phase, suggesting that the calcium substitution suppress the structural change of the P2-type NaxCoO2 to prevent the phase separation, resulting in the improved cycling performance.

  15. Structural basis for the transformation pathways of the sodium naproxen anhydrate–hydrate system

    PubMed Central

    Bond, Andrew D.; Cornett, Claus; Larsen, Flemming H.; Qu, Haiyan; Raijada, Dhara; Rantanen, Jukka

    2014-01-01

    Crystal structures are presented for two dihydrate polymorphs (DH-I and DH-II) of the non-steroidal anti-inflammatory drug sodium (S)-naproxen. The structure of DH-I is determined from twinned single crystals obtained by solution crystallization. DH-II is obtained by solid-state routes, and its structure is derived using powder X-ray diffraction, solid-state 13C and 23Na MAS NMR, and molecular modelling. The validity of both structures is supported by dispersion-corrected density functional theory (DFT-D) calculations. The structures of DH-I and DH-II, and in particular their relationships to the monohydrate (MH) and anhydrate (AH) structures, provide a basis to rationalize the observed transformation pathways in the sodium (S)-naproxen anhydrate–hydrate system. All structures contain Na+/carboxylate/H2O sections, alternating with sections containing the naproxen molecules. The structure of DH-I is essentially identical to MH in the naproxen region, containing face-to-face arrangements of the naphthalene rings, whereas the structure of DH-II is comparable to AH in the naproxen region, containing edge-to-face arrangements of the naphthalene rings. This structural similarity permits topotactic transformation between AH and DH-II, and between MH and DH-I, but requires re-organization of the naproxen molecules for transformation between any other pair of structures. The topotactic pathways dominate at room temperature or below, while the non-topotactic pathways become active at higher temperatures. Thermochemical data for the dehydration processes are rationalized in the light of this new structural information. PMID:25295174

  16. In situ X-ray pair distribution function analysis of accelerated carbonation of a synthetic calcium-?silicate?-hydrate gel

    SciTech Connect

    Morandeau, Antoine E.; White, Claire E. (Princeton)

    2015-01-01

    Calcium–silicate–hydrate (C–S–H) gel is the main binder component in hydrated ordinary Portland cement (OPC) paste, and is known to play a crucial role in the carbonation of cementitious materials, especially for more sustainable alternatives containing supplementary cementitious materials. However, the exact atomic structural changes that occur during carbonation of C–S–H gel remain unknown. Here, we investigate the local atomic structural changes that occur during carbonation of a synthetic calcium–silicate–hydrate gel exposed to pure CO? vapour, using in situ X-ray total scattering measurements and subsequent pair distribution function (PDF) analysis. By analysing both the reciprocal and real-space scattering data as the C–S–H carbonation reaction progresses, all phases present during the reaction (crystalline and non-crystalline) have been identified and quantified, with the results revealing the emergence of several polymorphs of crystalline calcium carbonate (vaterite and calcite) in addition to the decalcified C–S–H gel. Furthermore, the results point toward residual calcium being present in the amorphous decalcified gel, potentially in the form of an amorphous calcium carbonate phase. As a result of the quantification process, the reaction kinetics for the evolution of the individual phases have been obtained, revealing new information on the rate of growth/dissolution for each phase associated with C–S–H gel carbonation. Moreover, the investigation reveals that the use of real space diffraction data in the form of PDFs enables more accurate determination of the phases that develop during complex reaction processes such as C–S–H gel carbonation in comparison to the conventional reciprocal space Rietveld analysis approach.

  17. Stabilization of ZnCl2-containing wastes using calcium sulfoaluminate cement: cement hydration, strength development and volume stability.

    PubMed

    Berger, Stéphane; Cau Dit Coumes, Céline; Le Bescop, Patrick; Damidot, Denis

    2011-10-30

    The potential of calcium sulfoaluminate (CSA) cement was investigated to solidify and stabilize wastes containing large amounts of soluble zinc chloride (a strong inhibitor of Portland cement hydration). Hydration of pastes and mortars prepared with a 0.5 mol/L ZnCl(2) mixing solution was characterized over one year as a function of the gypsum content of the binder and the thermal history of the material. Blending the CSA clinker with 20% gypsum enabled its rapid hydration, with only very small delay compared with a reference prepared with pure water. It also improved the compressive strength of the hardened material and significantly reduced its expansion under wet curing. Moreover, the hydrates assemblage was less affected by a thermal treatment at early age simulating the temperature rise and fall occurring in a large-volume drum of cemented waste. Fully hydrated materials contained ettringite, amorphous aluminum hydroxide, strätlingite, together with AFm phases (Kuzel's salt associated with monosulfoaluminate or Friedel's salt depending on the gypsum content of the binder), and possibly C-(A)-S-H. Zinc was readily insolubilized and could not be detected in the pore solution extracted from cement pastes. PMID:21889260

  18. Hydrothermal Formation Of Hemi-hydrate Calcium Sulfate Whiskers In The Presence Of Additives

    SciTech Connect

    Luo, K. B. [Department of Chemical Engineering, Kunming University of Science and Technology, Kunming 650224 (China); Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Li, C. M.; Li, H. P.; Ning, P. [Department of Chemical Engineering, Kunming University of Science and Technology, Kunming 650224 (China); Xiang, L. [Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-11-24

    The influence of addictives on the hydrothermal formation of hemi-hydrate calcium sulfate (CaSO{sub 4{center_dot}}0.5H{sub 2}O) whiskers were discussed in this paper, using CaCl{sub 2} and Na{sub 2}SO{sub 4} as the reactants. The presence of NaCl, CaCl{sub 2} or Na{sub 2}SO{sub 4} increased the concentrations of Ca{sup 2+} and SO{sub 4}{sup 2-}, leading to the formation of CaSO{sub 4{center_dot}}0.5H{sub 2}O whiskers with aspect ratio lower than 50. The one dimensional growth of CaSO{sub 4{center_dot}}0.5H{sub 2}O whiskers was enhanced in water with no additives owing to the low super-saturation, leading to the formation of uniform whiskers with a length of 200-2000 {mu}m and an aspect ratio higher than 100.

  19. Dissolution-precipitation behaviour of ettringite, monosulfate, and calcium silicate hydrate

    SciTech Connect

    Baur, Isabel; Keller, Peter; Mavrocordatos, Denis; Wehrli, Bernhard; Johnson, C. Annette

    2004-02-01

    The stability of the cement minerals ettringite, monosulfate, and calcium silicate hydrate (C-S-H) was investigated to better understand the uptake of contaminants in waste-cement mixes. Suspensions were spiked with radioisotopes of components ({sup 45}Ca and {sup 35}SO{sub 4} for ettringite and monosulfate and {sup 45}Ca and {sup 32}Si for C-S-H) to observe their uptake behaviour within 0-70 days. A physical model was applied to determine dissolution-precipitation rates. An initial fast uptake was observed to occur in most systems, so the data obtained between 7 and 70 days were chosen for analysis. Dissolution-precipitation rates were in the range of 10{sup -11.5} to 10{sup -12.2} mol m{sup -2} s{sup -1} for all minerals. The whole solids would be dissolved and reprecipitated within 1-4 years. The measured dissolution-precipitation rates of pure cement minerals give the maximum rate for ion substitution processes with contaminants and are distinguishable from faster processes such as surface complexation and ion exchange processes.

  20. Development of montelukast sodium loaded niosomal carriers by film hydration technique.

    PubMed

    Kumar, Sumit; Awasthi, Rajendra

    2015-01-01

    The aim of this study was to develop and characterize montelukast sodium loaded niosomal drug carrier systems. The vesicles were prepared by film hydration technique using different surfactants. The optimized formulation was selected on the basis of results obtained from drug entrapment, morphology and in vitro drug release studies, and further evaluated for possible drug-excipient interaction, thermal behavior and drug physical state, before and after formulation using Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction analysis methods, respectively. The morphological characterization of vesicles was done using Transmission electron microscopy. Energy-dispersive X-ray spectroscopy system was used for elemental and dimensional analysis of developed vesicles. The vesicle surface charge was determined using zeta potential measurements. The results suggested that the optimized formulation had small size (103±6.01 nm) and high drug entrapment (72.20±2.10%). No chemical interaction was observed between the drug and excipients. The study revealed that Span 60 is a good nonionic surfactant for vesicle formulation. After 3 months storage at 2-8°C, the optimized formulation preserved stability in terms of formulation colour, drug amount and percent drug release. After 3 months, flocculation occured and hard cake was not formed on the settlement of vesicles. The preliminary results of this study suggest that the designed vesicles could enhance drug entrapment, reduce the initial burst release of drug and modulate the drug release. PMID:25910042

  1. Imaging of drug loading distributions in individual microspheres of calcium silicate hydrate - an X-ray spectromicroscopy study

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxuan; Wang, Zhiqiang; Wu, Jin; Wang, Jian; Zhu, Ying-Jie; Sham, Tsun-Kong

    2015-04-01

    Imaging is one of the most direct and ideal ways to track drug loading distributions in drug carriers on the molecular level, which will facilitate the optimization of drug carriers and drug loading capacities. Herein, we report the mapping of an individual mesoporous calcium silicate hydrate (CSH) microsphere before and after the loading of ibuprofen (IBU) and the interactions between drug carriers and drug molecules simultaneously by scanning transmission X-ray microscopy (STXM). Nanoscaled X-ray absorption near edge structure (XANES) spectroscopy clearly indicates that IBU is bonded to calcium and silicate sites via carboxylic acid groups. More importantly, STXM has been successfully used to determine the absolute thickness of IBU, revealing its distribution in the CSH microsphere.Imaging is one of the most direct and ideal ways to track drug loading distributions in drug carriers on the molecular level, which will facilitate the optimization of drug carriers and drug loading capacities. Herein, we report the mapping of an individual mesoporous calcium silicate hydrate (CSH) microsphere before and after the loading of ibuprofen (IBU) and the interactions between drug carriers and drug molecules simultaneously by scanning transmission X-ray microscopy (STXM). Nanoscaled X-ray absorption near edge structure (XANES) spectroscopy clearly indicates that IBU is bonded to calcium and silicate sites via carboxylic acid groups. More importantly, STXM has been successfully used to determine the absolute thickness of IBU, revealing its distribution in the CSH microsphere. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07471h

  2. High Dietary Sodium Intake Assessed by 24-hour Urine Specimen Increase Urinary Calcium Excretion and Bone Resorption Marker

    PubMed Central

    Park, Sun Mi; Jee, Jaehwan; Joung, Ji Young; Cho, Yoon Young; Sohn, Seo Young; Jin, Sang-Man; Hur, Kyu Yeon; Kim, Jae Hyeon; Kim, Sun Wook; Chung, Jae Hoon; Lee, Moon Kyu

    2014-01-01

    Background The average dietary sodium intake of Koreans is 2.6 times higher than the World Health Organization's recommended amount. The effect of a diet high in sodium on the skeletal system, especially osteoporosis, has not previously been examined in Korean postmenopausal women with low bone mass. We assessed the daily sodium intake, and determined the impact of sodium intake on urinary calcium excretion and bone resorption marker. Methods A retrospective review of medical records was performed for 86 postmenopausal subjects who were initially diagnosed with osteopenia or osteoporosis at the health promotion center. They were subsequently referred to the Division of Endocrinology and Metabolism between 2010 and 2013. All subjects completed a modified food frequency questionnaire. Twenty-four hour urine collection for sodium, calcium and creatinine excretion, and serum C-terminal telopeptides of type I collagen (CTX-I) were also obtained. Results The average amount of daily sodium and calcium intake were 3,466 mg and 813 mg, respectively. Average dietary sodium intake and 24-hour urinary sodium excretion showed significant positive linear correlation (r=0.29, P=0.006). There was also a significant positive linear correlation between 24-hour urine sodium and calcium excretion (r=0.42, P<0.001); CTX-I and 24-hour urinary calcium excretion (r=0.29, P=0.007). Conclusions Excessive sodium intake assessed by 24-hour urine specimen is associated with high calcium excretion in urine. High calcium excretion is also related to increasing bone resorption marker. PMID:25247156

  3. Non-decay type fast-setting calcium phosphate cement: composite with sodium alginate

    Microsoft Academic Search

    Kunio Ishikawa; Youji Miyamoto; Masayuki Kon; Masaru Nagayama; Kenzo Asaoka

    1995-01-01

    Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was prepared by introducing sodium alginate (0–2.0 wt%) into the liquid phase of FSCPC. nd-FSCPC was stable even when the cement paste was immersed in distilled water immediately after mixing, whereas conventional FSCPC (c-FSCPC) decayed completely within 1 min upon immersion. The setting time of the cement, approximately 5 min, was not dependent

  4. Economic comparison of calcium fumarate and sodium fumarate production by Rhizopus arrhizus

    Microsoft Academic Search

    Irene C. Gangl; William A. Weigand; Frederick A. Keller

    1990-01-01

    The economics of using Na2CO3 rather than CaCO3 as the neutralizing agent in fumaric acid production byRhizopus arrhizus is investigated and compared with the benzene route. Because sodium fumarate, unlike calcium fumarate, is soluble, downstream\\u000a processing is simplified by requiring less equipment and no heat, and also allows the reuse of cells. In spite of a fumaric\\u000a acid productivity (g\\/L\\/h)

  5. Involvement of the sodium-calcium exchanger 3 (NCX3) in ziram-induced calcium dysregulation and toxicity.

    PubMed

    Jin, J; Lao, A J; Katsura, M; Caputo, A; Schweizer, F E; Sokolow, S

    2014-12-01

    Ziram is a dimethyldithiocarbamate fungicide which can cause intraneuronal calcium (Ca(2+)) dysregulation and subsequently neuronal death. The signaling mechanisms underlying ziram-induced Ca(2+) dyshomeostasis and neurotoxicity are not fully understood. NCX3 is the third isoform of the sodium-calcium exchanger (NCX) family and plays an important role in regulating Ca(2+) homeostasis in excitable cells. We previously generated a mouse model deficient for the sodium-calcium exchanger 3 and showed that NCX3 is protective against ischemic damage. In the present study, we aim to examine whether NCX3 exerts a similar role against toxicological injury caused by the pesticide ziram. Our data show baby hamster kidney (BHK) cells stably transfected with NCX3 (BHK-NCX3) are more susceptible to ziram toxicity than cells transfected with the empty vector (BHK-WT). Increased toxicity in BHK-NCX3 was associated with a rapid rise in cytosolic Ca(2+) concentration [Ca(2+)]i induced by ziram. Profound mitochondrial dysfunction and ATP depletion were also observed in BHK-NCX3 cells following treatment with ziram. Lastly, primary dopaminergic neurons lacking NCX3 (NCX3(-/-)) were less sensitive to ziram neurotoxicity than wildtype control dopaminergic neurons. These results demonstrate that NCX3 genetic deletion protects against ziram-induced neurotoxicity and suggest NCX3 and its downstream molecular pathways as key factors involved in ziram toxicity. Our study identifies new molecular events through which pesticides (e.g. ziram) can lead to pathological features of degenerative diseases such as Parkinson's disease and indicates new targets to slow down neuronal degeneration. PMID:25284465

  6. The Thermodynamic Activity of Calcium Ion in Sodium Chloride-Calcium Chloride Electrolytes

    PubMed Central

    Butler, James N.

    1968-01-01

    Experimental data on the mean activity coefficient of CaCl2 in NaCl-CaCl2 mixtures at ionic strengths below 1 m have been used to prepare a table of activity coefficients for Ca++ in solutions of physiological interest. The establishment of an empirical calcium ion activity scale is discussed, and a number of possible assumptions are examined. The assumption ?++ = (?±)2 is suggested as being the simplest with a theoretical basis. PMID:5713452

  7. PHYTOTOXICITY OF SALTS IN COMPOSTED SEWAGE SLUDGE AND CORRELATION WITH SODIUM CHLORIDE, CALCIUM NITRATE, AND MAGNESIUM NITRATE

    Microsoft Academic Search

    Hong Cai; Ding Gao

    2011-01-01

    The phytotoxicity of salts in composted sewage sludge (CSS) was evaluated. Concentrations of sodium (Na), chloride (Cl), calcium (Ca), and magnesium (Mg) were present at levels that would induce salt stress in plants. Nutrient imbalances were also found that would adversely affect the use of CSS as a growth medium. To further understand the phytotoxic nature of these salts, sodium

  8. Ternary phase behaviour and vesicle formation of a sodium N-lauroylsarcosinate hydrate/1-decanol/water system

    NASA Astrophysics Data System (ADS)

    Akter, Nasima; Radiman, Shahidan; Mohamed, Faizal; Rahman, Irman Abdul; Reza, Mohammad Imam Hasan

    2011-08-01

    The phase behaviour of a system composed of amino acid-based surfactant (sodium N-lauroylsarcosinate hydrate), 1-decanol and deionised water was investigated for vesicle formation. Changing the molar ratio of the amphiphiles, two important aggregate structures were observed in the aqueous corner of the phase diagram. Two different sizes of microemulsions were found at two amphiphile-water boundaries. A stable single vesicle lobe was found for 1?2 molar ratios in 92 wt% water with vesicles approximately 100 nm in size and with high zeta potential value. Structural variation arises due to the reduction of electrostatic repulsions among the ionic headgroups of the surfactants and the hydration forces due to adsorbed water onto monolayer's. The balance of these two forces determines the aggregate structures. Analysis was followed by the molecular geometrical structure. These findings may have implications for the development of drug delivery systems for cancer treatments, as well as cosmetic and food formulations.

  9. SIK1/SOS2 networks: decoding sodium signals via calcium-responsive protein kinase pathways.

    PubMed

    Bertorello, Alejandro Mario; Zhu, Jian-Kang

    2009-07-01

    Changes in cellular ion levels can modulate distinct signaling networks aimed at correcting major disruptions in ion balances that might otherwise threaten cell growth and development. Salt-inducible kinase 1 (SIK1) and salt overly sensitive 2 (SOS2) are key protein kinases within such networks in mammalian and plant cells, respectively. In animals, SIK1 expression and activity are regulated in response to the salt content of the diet, and in plants SOS2 activity is controlled by the salinity of the soil. The specific ionic stress (elevated intracellular sodium) is followed by changes in intracellular calcium; the calcium signals are sensed by calcium-binding proteins and lead to activation of SIK1 or SOS2. These kinases target major plasma membrane transporters such as the Na(+),K(+)-ATPase in mammalian cells, and Na(+)/H(+) exchangers in the plasma membrane and membranes of intracellular vacuoles of plant cells. Activation of these networks prevents abnormal increases in intracellular sodium concentration. PMID:19247687

  10. Intracellular sodium-calcium dissociation in early contractile failure in hypoxic ferret papillary muscles.

    PubMed Central

    Guarnieri, T

    1987-01-01

    1. Intracellular sodium activity (aNai) and intracellular calcium activity (aCai) were measured in isolated quiescent right-ventricular ferret muscle: aNai = 9.8 +/- 2.2 mM and aCai = 71 +/- 19 nM. 2. When the muscles were exposed to 10(-5) M-ouabain, aNai increased to 20.4 +/- 3.1 mM while aCai increased to 260 +/- 99 nM. Twitch tension approximately doubled. 3. During prolonged hypoxia with glucose in the perfusate, aNai and twitch tension were unchanged. 4. During prolonged hypoxia with sucrose (substrate free) in the perfusate aNai increased to 18.9 +/- 3.1 mM, but aCai did not change. Twitch tension declined by 50%. 5. The addition of 10(-5) M-ouabain to the substrate-free hypoxic perfusate caused aNai to increase to 31.6 +/- 2.8 mM and aCai to increase to 150 +/- 35 nM. Twitch tension was unchanged. 6. These data indicate that only during prolonged substrate-free hypoxia does aNai increase. Despite the increase in aNai, no change in aCai is seen, unless the sodium-potassium pump is concomitantly inhibited. The lack of rise of aCai is consistent with inhibition of the sodium-calcium exchange, although other avenues of calcium exchange cannot be excluded. PMID:2443694

  11. Sodium bicarbonate-based hydration prevents contrast-induced nephropathy: a meta-analysis

    Microsoft Academic Search

    Pascal Meier; Dennis T Ko; Akira Tamura; Umesh Tamhane; Hitinder S Gurm

    2009-01-01

    BACKGROUND: Contrast-induced nephropathy is the leading cause of in-hospital acute renal failure. This side effect of contrast agents leads to increased morbidity, mortality, and health costs. Ensuring adequate hydration prior to contrast exposure is highly effective at preventing this complication, although the optimal hydration strategy to prevent contrast-induced nephropathy still remains an unresolved issue. Former meta-analyses and several recent studies

  12. Human water, sodium, and calcium regulation during space flight and exercise

    NASA Astrophysics Data System (ADS)

    Doty, S. E.; Seagrave, R. C.

    2000-05-01

    When one is exposed to microgravity, fluid which is normally pooled in the lower extremities is redistributed headward and weight bearing bones begin to demineralize due to reduced mechanical stresses. The kidney, which is the primary regulator of body fluid volume and composition, responds to the fluid shift and bone demineralization by increasing the urinary output of water, sodium, and calcium. This research involves developing a mathematical description of how water and electrolytes are internally redistributed and exchanged with the environment during space flight. This model consequently involves kidney function and the associated endocrine system. The model agrees well with actual data, including that a low sodium diet can prevent bone demineralization. Therefore, assumptions made to develop the model are most likely valid. Additionally, various levels of activity are also considered in the model since exercise may help to eliminate some of the undesired effects of space flight such as muscle atrophy and bone demineralization.

  13. Human water, sodium, and calcium regulation during space flight and exercise

    NASA Astrophysics Data System (ADS)

    Doty, S. E.; Seagrave, R. C.

    When one is exposed to microgravity, fluid which is normally pooled in the lower extremities is redistributed headward and weight bearing bones begin to demineralize due to reduced mechanical stresses. The kidney, which is the primary regulator of body fluid volume and composition, responds to the fluid shift and bone demineralization by increasing the urinary output of water, sodium, and calcium. This research involves developing a mathematical description of how water and electrolytes are internally redistributed and exchanged with the environment during space flight. This model consequently involves kidney function and the associated endocrine system. The model agrees well with actual data, including that a low sodium diet can prevent bone demineralization. Therefore, assumptions made to develop the model are most likely valid. Additionally, various levels of activity are also considered in the model since exercise may help to eliminate some of the undesired effects of space flight such as muscle atrophy and bone demineralization.

  14. Effect of intravenous calcium and oral sodium phosphate in cows with parturient paresis.

    PubMed

    Braun, U; Dumelin, J; Siegwart, N; Bleul, U; Hässig, M

    2007-06-01

    The goal of this study was to determine whether oral administration of sodium phosphate in conjunction with intravenous calcium is more efficaceous than intravenous calcium alone for the treatment of parturient paresis. Thirty cows with parturient paresis were examined and treated by the same veterinarian. The cows were divided randomly into two groups of 15 cows each. Cows in group A received 500 ml of a 40 per cent calcium borogluconate solution containing 15.65 g calcium gluconate and borogluconate, with a supplement of 6 per cent magnesium hypophosphite (9.85 g magnesium hypophosphite) intravenously over a period of approximately 15 min. Cows in group B received the same treatment as well as 350 g of monobasic sodium phosphate (70 g inorganic phosphate, NaH2PO4 2 H2O, Streuli) dissolved in 0.5 litres of distilled water orally via a stomach tube. After treatment, the heart rate, respiratory rate, rectal temperature, superficial body temperature, rumen motility, appetite and defecation of the cows were monitored every hour for eight h. The cows' attempts to rise and their ability to stand were also noted. Initially, the results of clinical examination and serum electrolyte analyses did not differ between the two groups of cows. Within one hour of treatment, stupor was not observed in any of the cows. The general demeanour after treatment did not differ significantly between the two groups. In both groups, the average rectal temperature increased within two hours of the initiation of treatment, from 38.0 +/- 0.95 degrees C to 38.5 +/- 0.40 degrees C. There was no significant difference in the recovery rate between the groups. Of the 30 cows, 22 (73.3 per cent) stood within eight hours of treatment (10 cows from group A and 12 cows from group B). The type of treatment did not affect the time required to stand: cows in group A stood within 47.3 +/- 44 minutes and cows in group B stood within 24.2 +/- 32 minutes after the start of treatment. Our findings do not support the hypothesis that oral treatment with 350 g of sodium phosphate together with intravenous infusion of calcium in cows with parturient paresis results in an improved outcome, even though all the cows had hypophosphataemia as well as hypocalcaemia. PMID:17645035

  15. X-ray microanalysis of calcium in fixed and in shock-frozen hydrated green algal cells: Mougeotia, Spirogyra and Zygnema

    NASA Astrophysics Data System (ADS)

    Rossbacher, Roland; Wagner, Gottfried; Pallaghy, Charles K.

    1984-04-01

    X-ray microanalysis, widely used for ionic detection in cell tissues, was performed on 0.5 ?m thick glutaraldehyde-osmiumtetroxide fixed cell sections. Calcium in a water-insoluble state was found in membrane bound vesicles of about 0.5 ?m in diameter. No other cell compartment showed a comparable calcium accumulation. In vivo staining by the fluorescent calcium indicator dye chlorotetracycline revealed a vesicular calcium pattern in Mougeotia matching the results by X-ray microanalysis: a dense population of calcium vesicles is located close to the chloroplast edge where the actin filaments are attached. The data find further support from X-ray microanalysis of shock-frozen hydrated Mougeotia cells and of the closely related green algal cells Spirogyra and Zygnema (Zygnemaceae). X-ray microanalysis as performed in this study seems a reliable tool for the detection of water-insoluble calcium stored by membrane-covered cytoplasmic compartments.

  16. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    NASA Astrophysics Data System (ADS)

    Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin; Wang, Xue-Lin

    2013-07-01

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.

  17. Mineral content of infant formula after treatment with sodium polystyrene sulfonate or calcium polystyrene sulfonate.

    PubMed

    Fassinger, N; Dabbagh, S; Mukhopadhyay, S; Lee, D Y

    1998-01-01

    Options for the management of infants with hyperkalemia secondary to renal insufficiency are limited for infants not maintained on dialysis. Precipitation of potassium (K+) from infant formula with sodium polystyrene sulfonate (KX) prior to feeding has been reported. However, its effect on calcium (Ca2+) and sodium (Na+) has not been quantitatively defined. The purpose of this study was to examine the effects of two K+ exchange resins: KX and calcium polystyrene sulfonate (RC) on Na+, K+, and Ca2+. Infant formula powder (Similac PM 60/40, Ross Laboratories, Columbus, OH, USA) was prepared with deionized water (DW) and KX or RC (1 g/mEq of K+) was added. The formula was decanted after 50 minutes and Na+, K+, and Ca2+ were assayed in the supernatant. Na+ and K+ were also assayed in ready-to-feed PM 60/40 (RTF). KX decreased the K+ concentration by 4.5 fold (P < 0.001) and increased the Na+ content by 3.8 fold (P < 0.001). In RC there was a 1.6-fold increase in Ca2+ content (P < 0.001), and a 13% decrease in K+ concentrations (P < 0.05). Preparation of the formula with DW reduced the K+ concentration by 30% compared to ready-to-feed formula (P < 0.001). We conclude that, although KX significantly reduces the K+ content of formulas, DW may be a more practical and convenient method of preparing formula for the hyperkalemic infant. PMID:10649740

  18. Modulation of the sodium-calcium exchanger in the rat kidney by different sequential stressors.

    PubMed

    Hudecova, S; Sedlakova, B; Kvetnansky, R; Ondrias, K; Krizanova, O

    2010-01-01

    Stress, if exaggerated, modulates a variety of metabolic pathways and results in development of serious health consequences. The cell membrane sodium-calcium exchanger (NCX) is a major calcium extrusion system and is also modulated by stress. It has been shown previously that mRNA, protein levels and activity of the type 1 NCX (NCX1) in the left ventricle of the rat heart are increased by stressors, such as immobilization or hypoxia. In this study we investigated whether exposure to a subsequent different stressor can affect gene expression, protein level and activity of the NCX1 in rat kidney compared to exposure to only one type of stressor. In these experiments, we used immobilization and cold as the model stressors.We found that cold exposure at 4 degrees C for 24 h, when applied after immobilization repeated seven times, completely abolished the immobilization-induced increase in NCX mRNA level and after 7 days cold exposure the increases in NCX1 protein and activity in rat kidney were also abolished. Permanently increased NCX1 expression can result in imbalance of cellular calcium homeostasis and thus contribute to kidney dysfunction. Based on our results, we conclude that exposure to a cold stressor can have a protective effect on the kidney in rats exposed previously to repeated immobilization stress. This might be explained by differential stimulation of sympathetic neural and adrenal medullary responses by these different stressors. PMID:19658027

  19. Hot alkali carbonation of sodium metaphosphate modified fly ash/calcium aluminate blend hydrothermal cements

    SciTech Connect

    Sugama, T. [Brookhaven National Lab., Upton, NY (United States). Energy Efficiency and Conservation Div.] [Brookhaven National Lab., Upton, NY (United States). Energy Efficiency and Conservation Div.

    1996-11-01

    Sodium metaphosphate-modified fly ash/calcium aluminate blend (SFCB) cements were prepared by autoclaving for 1 day at 300 C and their resistance was evaluated in a highly concentrated Na{sub 2}CO{sub 3} solution at 300 C. The hydroxyapatite and analcime phases formed in the autoclaved SFCB cements played an essential role in conferring resistance to the degradation of cements caused by alkali carbonation. Although the carbonating reaction of the analcime phase led to the formation of cancrinite, this analcime cancrinite transformation did not show any influence on the changes in the mechanical and physical properties of the cements. Additionally, there was no formation of the water-soluble calcium bicarbonate in the cements exposed for 28 days. Contrarily, the conventional class G cement systems were very vulnerable to a hot alkali carbonation. The major reason for the damage caused by carbonation of the cements was the fact that the xonotlite phase formed in the 300{degree} autoclaved cements was converted into two carbonation products, calcite and pectolite. Furthermore, the reaction between calcite and carbonic acid derived from Na{sub 2}CO{sub 3} led to the formation of water-soluble calcium bicarbonate, thereby causing the alteration of dense structures into porous ones and the loss of strength of cements.

  20. EXAFS study of Nd(III) uptake by amorphous calcium silicate hydrates (CSH) P. Mandaliev a,b,*, R. Dhn a

    E-print Network

    Wehrli, Bernhard

    EXAFS study of Nd(III) uptake by amorphous calcium silicate hydrates (C­S­H) P. Mandaliev a,b,*, R­S­H) phases Extended X-ray absorption fine structure (EXAFS) spectroscopy Cementitious materials Radionuclides (EXAFS) spectroscopy. The structural parameters derived from EXAFS were compared with those predicted

  1. Calcium-43 chemical shift and electric field gradient tensor interplay: a sensitive probe of structure, polymorphism, and hydration.

    PubMed

    Widdifield, Cory M; Moudrakovski, Igor; Bryce, David L

    2014-07-14

    Calcium is the 5th most abundant element on earth, and is found in numerous biological tissues, proteins, materials, and increasingly in catalysts. However, due to a number of unfavourable nuclear properties, such as a low magnetogyric ratio, very low natural abundance, and its nuclear electric quadrupole moment, development of solid-state (43)Ca NMR has been constrained relative to similar nuclides. In this study, 12 commonly-available calcium compounds are analyzed via(43)Ca solid-state NMR and the information which may be obtained by the measurement of both the (43)Ca electric field gradient (EFG) and chemical shift tensors (the latter of which are extremely rare with only a handful of literature examples) is discussed. Combined with density functional theory (DFT) computations, this 'tensor interplay' is, for the first time for (43)Ca, illustrated to be diagnostic in distinguishing polymorphs (e.g., calcium formate), and the degree of hydration (e.g., CaCl2·2H2O and calcium tartrate tetrahydrate). For Ca(OH)2, we outline the first example of (1)H to (43)Ca cross-polarization on a sample at natural abundance in (43)Ca. Using prior knowledge of the relationship between the isotropic calcium chemical shift and the calcium quadrupolar coupling constant (CQ) with coordination number, we postulate the coordination number in a sample of calcium levulinate dihydrate, which does not have a known crystal structure. Natural samples of CaCO3 (aragonite polymorph) are used to show that the synthetic structure is present in nature. Gauge-including projector augmented-wave (GIPAW) DFT computations using accepted crystal structures for many of these systems generally result in calculated NMR tensor parameters which are in very good agreement with the experimental observations. This combination of (43)Ca NMR measurements with GIPAW DFT ultimately allows us to establish clear correlations between various solid-state (43)Ca NMR observables and selected structural parameters, such as unit cell dimensions and average Ca-O bond distances. PMID:24874995

  2. Lead and zinc retention during hydration of tri-calcium silicate: A study by sorption isotherms and {sup 29}Si nuclear magnetic resonance spectroscopy

    SciTech Connect

    Moulin, I.; Bottero, J.Y. [CEREGE, Aix-en-Provence (France)] [CEREGE, Aix-en-Provence (France); Stone, W.E.E. [CEREGE, Aix-en-Provence (France)] [CEREGE, Aix-en-Provence (France); [MRAC, Bruxelles (Belgium). Section de Physico-Chimie Minerale; Sanz, J. [CSIC Cantoblanco, Madrid (Spain). Inst. Cienca de Materiales] [CSIC Cantoblanco, Madrid (Spain). Inst. Cienca de Materiales; Mosnier, F. [SITA, Paris (France)] [SITA, Paris (France); Haehnel, C. [ATILH, Paris La Defense (France)] [ATILH, Paris La Defense (France)

    1999-04-13

    In cement-based materials heavy metals contents are rarely larger than a few hundred parts per million. Sorption isotherms of Zn(II) and Pb(II) carried out on nonhydrated (C{sub 3}S) and hydrated (C-S-H) calcium silicate show t hat lead and zinc have different affinities for calcium silicate in a concentration range lower than the saturation concentration values of PbO and calcium zinc hydroxide. Lead has a much higher affinity than zinc for both nonhydrated and hydrated calcium silicate. Furthermore, the different retention sites of zinc and lead in hydrated calcium silicate have been investigated by {sup 29}Si nuclear magnetic resonance (NMR) spectroscopy. A spectral line analysis clearly shows that structural retention mechanisms are involved for both ions. Indeed, the additional lines at {minus}85.6 or {minus}85.9 ppm that appear in the NMR spectra have been attributed to Q{sub 1Me} sites involving Si-O-Pb and Si-O-Zn bonds, respectively.

  3. Evaluation of genotoxic effects of sodium propionate, calcium propionate and potassium propionate on the root meristem cells of Allium cepa

    Microsoft Academic Search

    ?ifa Türko?lu

    2008-01-01

    The effects of different treatments with food preservatives, sodium propionate (SP), calcium propionate (CP) and potassium propionate (PP), on the cytology and DNA content of Allium cepa were investigated. Five concentrations of these additives – 1000, 1500, 2000, 2500, and 3000ppm – were applied for 24, 48, and 72h. All concentrations of these chemicals showed an inhibitory effect on cell

  4. Combination of sodium chlorite and calcium propionate reduces enzymatic browning and microbial population of fresh-cut ‘Granny Smith’ apples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tissue browning and microbial growth are the main concerns associated with fresh-cut apples. In this study, effects of sodium chlorite (SC) and calcium propionate (CP), individually and combined, on quality and microbial population of apple slices were investigated. ‘Granny Smith’ apple slices, dipp...

  5. Application of ultrasonic testing to describe the hydration of calcium aluminate cement at the early age

    Microsoft Academic Search

    T Chotard; N Gimet-Breart; A Smith; D Fargeot; J. P Bonnet; C Gault

    2001-01-01

    Nondestructive and in situ characterisation techniques, such as ultrasonic measurements, permit to follow cement hydration at the early age from a few minutes to a few hours after mixing. The technique reported in this paper is based on measurements in reflection modes. Results concerning an aluminous cement, Secar71, are presented (water-to-cement weight ratio (W\\/C): 0.3 and 0.4; temperature of measurement:

  6. Calcium

    MedlinePLUS

    ... Consumer Datos en español Health Professional Other Resources Calcium Fact Sheet for Consumers What is calcium and what does it do? Calcium is a ... find out more about calcium? Disclaimer How much calcium do I need? The amount of calcium you ...

  7. SIK1 is part of a cell sodium-sensing network that regulates active sodium transport through a calcium-dependent process.

    PubMed

    Sjöström, Mattias; Stenström, Karin; Eneling, Kristina; Zwiller, Jean; Katz, Adrian I; Takemori, Hiroshi; Bertorello, Alejandro M

    2007-10-23

    In mammalian cells, active sodium transport and its derived functions (e.g., plasma membrane potential) are dictated by the activity of the Na(+),K(+)-ATPase (NK), whose regulation is essential for maintaining cell volume and composition, as well as other vital cell functions. Here we report the existence of a salt-inducible kinase-1 (SIK1) that associates constitutively with the NK regulatory complex and is responsible for increases in its catalytic activity following small elevations in intracellular sodium concentrations. Increases in intracellular sodium are paralleled by elevations in intracellular calcium through the reversible Na(+)/Ca(2+) exchanger, leading to the activation of SIK1 (Thr-322 phosphorylation) by a calcium calmodulin-dependent kinase. Activation of SIK1 results in the dephosphorylation of the NK alpha-subunit and an increase in its catalytic activity. A protein phosphatase 2A/phosphatase methylesterase-1 (PME-1) complex, which constitutively associates with the NK alpha-subunit, is activated by SIK1 through phosphorylation of PME-1 and its dissociation from the complex. These observations illustrate the existence of a distinct intracellular signaling network, with SIK1 at its core, which is triggered by a monovalent cation (Na(+)) and links sodium permeability to its active transport. PMID:17939993

  8. Intracellular calcium and its sodium-independent regulation in voltage-clamped snail neurones.

    PubMed Central

    Kennedy, H J; Thomas, R C

    1995-01-01

    1. We have used both Ca(2+)-sensitive microelectrodes and fura-2 to measure the intracellular free calcium ion concentration ([Ca2+]i or its negative log, pCai) of snail neurones voltage clamped to -50 or -60 mV. Using Ca(2+)-sensitive microelectrodes, [Ca2+]i was found to be approximately 174 nM and pCai, 6.76 +/- 0.09 (mean +/- S.E.M.; n = 11); using fura-2, [Ca2+]i was approximately 40 nM and pCai, 7.44 +/- 0.06 (mean +/- S.E.M., n = 10). 2. Depolarizations (1-20 s) caused an increase in [Ca2+]i which was abolished by removal of extracellular Ca2+, indicating that the rise in [Ca2+]i was due to Ca2+ influx through voltage-activated Ca2+ channels. 3. Caffeine (10-20 mM) caused an increase in [Ca2+]i in the presence or absence of extracellular Ca2+. The effects of caffeine on [Ca2+]i could be prevented by ryanodine. 4. Thapsigargin, an inhibitor of the endoplasmic reticulum Ca(2+)-ATPase, caused a small increase in resting [Ca2+]i and slowed the rate of recovery from Ca2+ loads following 20 s depolarizations. 5. Neither replacement of extracellular sodium with N-methyl-D-glucamine (NMDG), nor loading the cells with intracellular sodium, had any effect on resting [Ca2+]i or the rate of recovery of [Ca2+]i following depolarizations. 6. The mitochondrial uncoupling agent carbonyl cyanide m-chlorophenylhydrazone (CCmP) caused a small gradual rise in resting [Ca2+]i. Removal of extracellular sodium during exposure to CCmP had no further effect on [Ca2+]i. 7. Intracellular orthovanadate caused an increase in resting [Ca2+]i and prevented the full recovery of [Ca2+]i following small Ca2+ loads, but removal of extracellular sodium did not cause a rise in [Ca2+]i. We conclude that there is no Na(+)-Ca2+ exchanger present in the cell body of these neurones and that [Ca2+]i is maintained by an ATP-dependent Ca2+ pump. Images Figure 1 PMID:7623274

  9. Crystallization kinetics of calcium oxalate hydrates studied by scanning confocal interference microscopy

    NASA Astrophysics Data System (ADS)

    Grohe, Bernd; Rogers, Kem A.; Goldberg, Harvey A.; Hunter, Graeme K.

    2006-10-01

    Scanning confocal interference microscopy (SCIM) is an optical technique that allows the visualization of structures below the limits of classical optical microscopy (?250 nm). This study represents the first use of SCIM to analyze the formation of calcium oxalate crystals, the major constituent of kidney stones. Crystals were nucleated and grown on the glass bottom of Petri dishes in the presence and absence of the polyelectrolyte inhibitor poly- L-aspartic acid (poly-asp). In the absence of poly-asp, monoclinic calcium oxalate monohydrate (COM) nucleated from {1 0 0} or {0 1 0} faces. The first observed particles were 70-120 nm in diameter and grew by a step-like progression in the [0 0 1] and [0 1 0] directions. Addition of poly-asp had several effects on calcium oxalate formation. First, the number of particles was increased, but their sizes were decreased. Second, the rate of COM growth in the [0 0 1] direction was decreased to a greater extent than the rate along [0 1 0]. Third, the formation of tetragonal calcium oxalate dihydrate (COD) crystals was favored. Fourth, the rates of COD growth along <1 1 0> and allied directions were decreased, whereas that parallel to <0 0 1> is increased. Sequences of highly resolved growth fronts show step displacement for COM and moving crystal edges for COD. Analysis of image sequences suggested that growth is strongly affected by competing and alternating processes, in which diffusion processes are rate-limiting and induce nonlinear growth. This study shows that SCIM is a powerful technique for the quantitative analysis of crystallization processes and for determining the mode of action of inhibitors.

  10. Calcium

    MedlinePLUS

    ... of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, but is absorbed best when taken ... antacid products, such as Tums® and Rolaids®, contain calcium carbonate. Each pill or chew provides 200–400 mg ...

  11. Sodium and potassium salts of dichloroisocyanuric acid and their hydrates as antimicrobials agents studied by 35Cl-NQR spectroscopy and DFT calculations

    Microsoft Academic Search

    A. Walczak; B. Brycki; M. Kaczmarek; O. Kh. Poleshchuk; M. Ostafin; B. Nogaj

    2006-01-01

    The electronic structure of dichloroisocyanuric acid derivatives was analysed by 35Cl-NQR spectroscopy and DFT calculations. Here we concentrate our attention on three different factors: type of metallic substituent (sodium and potassium), temperature of the sample (liquid nitrogen and room) and degree of hydration (an amount of water molecules attached to analysed compounds). In particular, all the variations in 35Cl-NQR frequencies

  12. Composition-solubility-structure relationships in calcium (alkali) aluminosilicate hydrate (C-(N,K-)A-S-H).

    PubMed

    Myers, Rupert J; L'Hôpital, Emilie; Provis, John L; Lothenbach, Barbara

    2015-07-21

    The interplay between the solubility, structure and chemical composition of calcium (alkali) aluminosilicate hydrate (C-(N,K-)A-S-H) equilibrated at 50 °C is investigated in this paper. The tobermorite-like C-(N,K-)A-S-H products are more crystalline in the presence of alkalis, and generally have larger basal spacings at lower Ca/Si ratios. Both Na and K are incorporated into the interlayer space of the C-(N,K-)A-S-H phases, with more alkali uptake observed at higher alkali and lower Ca content. No relationship between Al and alkali uptake is identified at the Al concentrations investigated (Al/Si ? 0.1). More stable C-(N,K-)A-S-H is formed at higher alkali content, but this factor is only significant in some samples with Ca/Si ratios ?1. Shorter chain lengths are formed at higher alkali and Ca content, and cross-linking between (alumino)silicate chains in the tobermorite-like structure is greatly promoted by increasing alkali and Al concentrations. The calculated solubility products do not depend greatly on the mean chain length in C-(N,K-)A-S-H at a constant Ca/(Al + Si) ratio, or the Al/Si ratio in C-(N,K-)A-S-H. These results are important for understanding the chemical stability of C-(N,K-)A-S-H, which is a key phase formed in the majority of cements and concretes used worldwide. PMID:26134354

  13. Similarities and peculiarities between the crystal structures of the hydrates of sodium sulfate and selenate.

    PubMed

    Kamburov, Stoyan; Schmidt, Horst; Voigt, Wolfgang; Balarew, Christo

    2014-08-01

    The crystal structures of the two hydrates Na2SeO4·10H2O and Na2SeO4·7.5H2O are studied for the first time. The structures of Na2SO4·10H2O and Na2SO4·7H2O are reinvestigated as a function of temperature with respect to the degree of disorder of the O atoms of SO4(2-) in the decahydrate and the O atom of water in the heptahydrate. For Na2SO4·10H2O, the unit site occupancy factor (SOF) of O atoms of SO4(2-) was determined at 120?K. After the temperature dependence of the lattice parameters was studied from 120 to 260?K, it was shown that SOF decreased from 1.0 at 120?K to 0.247 at room temperature. The interesting fact that two salts with different chemical compositions and different crystal structures (Na2SO4·7H2O, tetragonal, space group P4(1)2(1)2 and Na2SeO4·7.5H2O, monoclinic, space group C2/c) can act mutually as a crystal nucleus is accounted for by similarities in certain fragments of their crystal structures. This phenomenon is attributed to similarities between particular elements of their structures. PMID:25080250

  14. Calcium-Mediated Regulation of Proton-Coupled Sodium Transport - Final Report

    SciTech Connect

    Schumaker, Karen S [Professor] [Professor

    2013-10-24

    The long-term goal of our experiments was to understand mechanisms that regulate energy coupling by ion currents in plants. Activities of living organisms require chemical, mechanical, osmotic or electrical work, the energy for which is supplied by metabolism. Adenosine triphosphate (ATP) has long been recognized as the universal energy currency, with metabolism supporting the synthesis of ATP and the hydrolysis of ATP being used for the subsequent work. However, ATP is not the only energy currency in living organisms. A second and very different energy currency links metabolism to work by the movement of ions passing from one side of a membrane to the other. These ion currents play a major role in energy capture and they support a range of physiological processes from the active transport of nutrients to the spatial control of growth and development. In Arabidopsis thaliana (Arabidopsis), the activity of a plasma membrane Na+/H+ exchanger, SALT OVERLY SENSITIVE1 (SOS1), is essential for regulation of sodium ion homeostasis during plant growth in saline conditions. Mutations in SOS1 result in severely reduced seedling growth in the presence of salt compared to the growth of wild type. SOS1 is a secondary active transporter coupling movement of sodium ions out of the cell using energy stored in the transplasma membrane proton gradient, thereby preventing the build-up of toxic levels of sodium in the cytosol. SOS1 is regulated by complexes containing the SOS2 and CALCINEURIN B-LIKE10 (CBL10) or SOS3 proteins. CBL10 and SOS3 (also identified as CBL4) encode EF-hand calcium sensors that interact physically with and activate SOS2, a serine/threonine protein kinase. The CBL10/SOS2 or SOS3/SOS2 complexes then activate SOS1 Na+/H+ exchange activity. We completed our studies to understand how SOS1 activity is regulated. Specifically, we asked: (1) how does CBL10 regulate SOS1 activity? (2) What role do two putative CBL10-interacting proteins play in SOS1 regulation? (3) Are there differences in the regulation and/or activity of SOS1 in plants differing in their adaptation to salinity?

  15. Selectivity filters and cysteine-rich extracellular loops in voltage-gated sodium, calcium, and NALCN channels

    PubMed Central

    Stephens, Robert F.; Guan, W.; Zhorov, Boris S.; Spafford, J. David

    2015-01-01

    How nature discriminates sodium from calcium ions in eukaryotic channels has been difficult to resolve because they contain four homologous, but markedly different repeat domains. We glean clues from analyzing the changing pore region in sodium, calcium and NALCN channels, from single-cell eukaryotes to mammals. Alternative splicing in invertebrate homologs provides insights into different structural features underlying calcium and sodium selectivity. NALCN generates alternative ion selectivity with splicing that changes the high field strength (HFS) site at the narrowest level of the hourglass shaped pore where the selectivity filter is located. Alternative splicing creates NALCN isoforms, in which the HFS site has a ring of glutamates contributed by all four repeat domains (EEEE), or three glutamates and a lysine residue in the third (EEKE) or second (EKEE) position. Alternative splicing provides sodium and/or calcium selectivity in T-type channels with extracellular loops between S5 and P-helices (S5P) of different lengths that contain three or five cysteines. All eukaryotic channels have a set of eight core cysteines in extracellular regions, but the T-type channels have an infusion of 4–12 extra cysteines in extracellular regions. The pattern of conservation suggests a possible pairing of long loops in Domains I and III, which are bridged with core cysteines in NALCN, Cav, and Nav channels, and pairing of shorter loops in Domains II and IV in T-type channel through disulfide bonds involving T-type specific cysteines. Extracellular turrets of increasing lengths in potassium channels (Kir2.2, hERG, and K2P1) contribute to a changing landscape above the pore selectivity filter that can limit drug access and serve as an ion pre-filter before ions reach the pore selectivity filter below. Pairing of extended loops likely contributes to the large extracellular appendage as seen in single particle electron cryo-microscopy images of the eel Nav1 channel. PMID:26042044

  16. Selectivity filters and cysteine-rich extracellular loops in voltage-gated sodium, calcium, and NALCN channels.

    PubMed

    Stephens, Robert F; Guan, W; Zhorov, Boris S; Spafford, J David

    2015-01-01

    How nature discriminates sodium from calcium ions in eukaryotic channels has been difficult to resolve because they contain four homologous, but markedly different repeat domains. We glean clues from analyzing the changing pore region in sodium, calcium and NALCN channels, from single-cell eukaryotes to mammals. Alternative splicing in invertebrate homologs provides insights into different structural features underlying calcium and sodium selectivity. NALCN generates alternative ion selectivity with splicing that changes the high field strength (HFS) site at the narrowest level of the hourglass shaped pore where the selectivity filter is located. Alternative splicing creates NALCN isoforms, in which the HFS site has a ring of glutamates contributed by all four repeat domains (EEEE), or three glutamates and a lysine residue in the third (EEKE) or second (EKEE) position. Alternative splicing provides sodium and/or calcium selectivity in T-type channels with extracellular loops between S5 and P-helices (S5P) of different lengths that contain three or five cysteines. All eukaryotic channels have a set of eight core cysteines in extracellular regions, but the T-type channels have an infusion of 4-12 extra cysteines in extracellular regions. The pattern of conservation suggests a possible pairing of long loops in Domains I and III, which are bridged with core cysteines in NALCN, Cav, and Nav channels, and pairing of shorter loops in Domains II and IV in T-type channel through disulfide bonds involving T-type specific cysteines. Extracellular turrets of increasing lengths in potassium channels (Kir2.2, hERG, and K2P1) contribute to a changing landscape above the pore selectivity filter that can limit drug access and serve as an ion pre-filter before ions reach the pore selectivity filter below. Pairing of extended loops likely contributes to the large extracellular appendage as seen in single particle electron cryo-microscopy images of the eel Nav1 channel. PMID:26042044

  17. Structural Insight into the Ion-Exchange Mechanism of the Sodium/Calcium Exchanger

    SciTech Connect

    Liao, Jun; Li, Hua; Zeng, Weizhong; Sauer, David B.; Belmares, Ricardo; Jiang, Youxing (UTSMC)

    2012-06-19

    Sodium/calcium (Na{sup +}/Ca{sup 2+}) exchangers (NCX) are membrane transporters that play an essential role in maintaining the homeostasis of cytosolic Ca{sup 2+} for cell signaling. We demonstrated the Na{sup +}/Ca{sup 2+}-exchange function of an NCX from Methanococcus jannaschii (NCX{_}Mj) and report its 1.9 angstrom crystal structure in an outward-facing conformation. Containing 10 transmembrane helices, the two halves of NCX{_}Mj share a similar structure with opposite orientation. Four ion-binding sites cluster at the center of the protein: one specific for Ca{sup 2+} and three that likely bind Na{sup +}. Two passageways allow for Na{sup +} and Ca{sup 2+} access to the central ion-binding sites from the extracellular side. Based on the symmetry of NCX{_}Mj and its ability to catalyze bidirectional ion-exchange reactions, we propose a structure model for the inward-facing NCX{_}Mj.

  18. Herbal extracts of Tribulus terrestris and Bergenia ligulata inhibit growth of calcium oxalate monohydrate crystals in vitro

    Microsoft Academic Search

    V. S. Joshi; B. B. Parekh; M. J. Joshi; A. B. Vaidya

    2005-01-01

    A large number of people in this world are suffering from urinary stone problem. Calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) containing stones (calculi) are commonly found. In the present study, COM crystals were grown by a double diffusion gel growth technique using U-tubes. The gel was prepared from hydrated sodium metasilicate solution. The gel framework acts like

  19. Hydration and strength development of binder based on high-calcium oil shale fly ash. Part 2: Influence of curing conditions on long-term stability

    SciTech Connect

    Freidin, C.

    1999-11-01

    The distinguishing feature of high-calcium oil shale fly ash (HCOSFA) used in experiments is the high amount of free CaO and SO{sub 3} in form of lime and anhydrite. Strength development as well as the microstructure and composition of the new formations of fly ash binder (FAB) based on HCOSFA and low-calcium coal fly ash after curing in different conditions and long-term exposure in various environments were studied. It was determined that moist air and water are the most favorable conditions for aging processes of FAB. In atmospheric air three stages in strength change of cured FAB are observed: increase of compressive strength over 1 month; sharp drop after 1 month up to the 3 to months; stabilization or slowdown of loss in strength after 3 to 6 months of exposure. The duration of the second and third stages depends on HCOSFA content and does not depend on curing conditions. One of the hydration products of FAB is ettringite. Its instability in air could be a reason for the decrease in strength of FAB and some disintegration of the hardened system. In the presence of low-calcium coal fly ash, additional amounts of stable calcium silicate hydrates are formed during FAB curing especially during steam curing. This has a positive effect on compressive strength and stability of FAB in atmospheric air.

  20. Preparation, crystal structures and rapid hydration of P2- and P3-type sodium chromium antimony oxides

    SciTech Connect

    Pospelov, A.A. [Southern Federal University, 7 ul. Zorge, Rostov-na-Donu 344090 (Russian Federation); Nalbandyan, V.B., E-mail: vbn@sfedu.r [Southern Federal University, 7 ul. Zorge, Rostov-na-Donu 344090 (Russian Federation)

    2011-05-15

    Two new Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2} compounds have been prepared by solid-state reactions in argon. Their structures have been determined by the X-ray Rietveld method. Both new phases together with NaCrO{sub 2}-based solid solution comprise brucite-like layers of edge-shared (Cr,Sb)O{sub 6} octahedra but differ by packing mode of the layers and coordination of the interlayer Na{sup +} ions. A P3 phase exists at x{approx}0.5-0.58. It is rhombohedral (R3-bar m), a=2.966, c=16.937 A at x{approx}0.58, with 29% Na{sup +} occupancy of trigonal prisms. A P2 phase exists at x{approx}0.6-0.7. It is hexagonal (P6{sub 3}/mmc), a=2.960, c=11.190 A at x{approx}0.7, with 37% and 33% Na{sup +} occupancy of two non-equivalent trigonal prisms. Both P2 and P3 phases rapidly absorb moisture in air; packing mode is preserved, the a parameter changes slightly but c increases by 24-25%. Very high sodium ion conductivity is predicted for both P2 and P3 anhydrous phases. -- Graphical Abstract: Polyhedral presentation of layered structures of Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2}. (Cr,Sb)O{sub 6} octahedra are green. Part of the sodium prisms are open to show short distances between sodium sites which cannot be occupied simultaneously. Display Omitted highlights: > Two new layered Na{sub x}[Cr{sub (1+x)/2}Sb{sub (1-x)/2}]O{sub 2} phases, P2 and P3, have been prepared in argon. > Interlayer O-O distances are larger than in Na{sub x}(M,Ti)O{sub 2} analogs (M=Cr,Ni,Li). > As a result, both rapidly hydrate in air with c-axis expansion of 24-25%. > Bottleneck radii are also larger, and this predicts very high Na{sup +}-ion conductivity.

  1. 21 CFR 872.3490 - Carboxymethylcellulose sodium and/or polyvinylmethylether maleic acid calcium-sodium double salt...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...3490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3490 Carboxymethylcellulose sodium and/or polyvinylmethylether...

  2. A Raman spectroscopic study of glasses along the joins silica-calcium aluminate, silica-sodium aluminate, and silica-potassium aluminate

    Microsoft Academic Search

    Paul McMillan; Bernard Piriou; Alexandra Navrotsky

    1982-01-01

    Aluminosilicate glasses with compositions along the joins silica-calcium aluminate, silica sodium aluminate and silica-potassium aluminate have been prepared by conventional and solar melting techniques and studied by Raman spectroscopy. The Raman spectra of crystalline calcium aluminate, anorthite and silica polymorphs are discussed in relation to their crystal structures, and compared with the spectra of the corresponding glasses. The glass and

  3. Prophylactic and therapeutic properties of a sodium citrate preparation in the management of calcium oxalate urolithiasis: randomized, placebo-controlled trial

    Microsoft Academic Search

    Shameez Allie-Hamdulay; Allen L. Rodgers

    2005-01-01

    The purpose of this study was to investigate the prophylactic and therapeutic effects of a hitherto untested preparation containing sodium citrate in the management of calcium oxalate urolithiasis. In this study, a host of calcium oxalate kidney stone risk factors was investigated using a randomised, placebo controlled, “within-patient” clinical trial. The trial involved four groups of subjects: healthy male controls,

  4. Calcium balance and acid-base status of women as affected by increased protein intake and by sodium bicarbonate ingestion13

    Microsoft Academic Search

    Josephine Lutz

    Six women, aged 38 to 62 yr. participated in a 40-day metabolic study to investigate the effect of level of protein intake and of sodium bicarbonate ingestion on urinary calcium, net calcium balance, net renal acid excretion, and arterialized venous blood pH and bicarbonate ion concentration. The diet contained 44 g protein during the first 16 days and 102 g

  5. The effect of Portuguese Man-of-war ( Physalia physalis) venom on calcium, sodium and potassium fluxes of cultured embryonic chick heart cells

    Microsoft Academic Search

    Lincoln Edwards; Eva Luo; Raymond Hall; Ramon R Gonzalez; David A Hessinger

    2000-01-01

    Portuguese Man-of-war venom markedly increases calcium (45Ca2+) influx into primary, cultured, embryonic chick heart cells. This action is dose-dependent, but is unaffected by organic calcium blockers (diltiazem, verapamil, nifedipine, nimodipine and mibefradil). On the other hand, certain trivalent (La3+, Gd3+) and divalent (Zn2+, Ni2+, Cu2+, Mn2+) metals inhibit venom-induced calcium influx. Sodium (22Na+) influx into chick heart cells is also

  6. Formation of leadhillite and calcium lead silicate hydrate (C-Pb-S-H) in the solidification/stabilization of lead contaminants.

    PubMed

    Lee, Dongjin

    2007-01-01

    In this study, we have investigated the structure of Pb-doped solidified waste forms (SWF) for assessment of lead fixation. A large quantity of lead precipitates produced during the S/S, based upon the results of cement-water solution analysis, X-ray diffraction and electron probe microanalysis/electron dispersive spectroscopy investigations, have been shown to be principally leadhillite (lead carbonate sulfate hydroxide, Pb(4)SO(4)(CO(3))(2)(OH)(2)), lead carbonate hydroxide hydrate (3PbCO(3).2Pb(OH)(2).H(2)O) and two other unidentified lead salts. In the long curing, the lead species dissolved from the lead precipitates are fixed into the cement matrix, forming a gelling calcium lead silicate hydrate during cement-based solidification. On leaching the lead precipitates such as leadhillite were markedly dissolved/released and some dissolved lead species were adsorbed to silicate-rich surface of leached SWF with the subsequent formation of mainly amorphous gel of calcium lead silicate hydrate. PMID:16934855

  7. Synthesis of sodium caseinate-calcium carbonate microspheres and their mineralization to bone-like apatite

    NASA Astrophysics Data System (ADS)

    Xu, Zhewu; Liang, Guobin; Jin, Lin; Wang, Zhenling; Xing, Chao; Jiange, Qing; Zhang, Zhiguang

    2014-06-01

    Phosphoproteins can induce and stabilize calcium carbonate (CaCO3) vaterite, which has desirable features for high reactivity. The purpose of this study was to synthesize bioactive CaCO3 microspheres for bone regeneration. Sodium caseinate (NaCas)-containing CaCO3 microspheres, with the crystal phase of vaterite, were synthesized by fast precipitation in an aqueous solution of CaCl2, Na2CO3, and 2 mg/mL of NaCas. The uniform microspheres exhibited rougher surfaces and lower negative charges than CaCO3 particles without NaCas addition. Fourier-transform infrared spectroscopy (FT-IR) of the microspheres showed characteristic peaks or bands corresponding to phosphate and hydroxyl groups. Thermogravimetric analysis (TGA) curves exhibited approximately 5% weight loss below 600 °C due to the decomposition of NaCas. Scanning electron microscope (SEM) images showed lath-like hydroxyapatite (HAp) on the surface after soaking in simulated body fluid (SBF) at 37 °C for 5 and 10 days. Energy dispersive X-ray spectrometry (EDS) revealed that the agglomerates were composed of Ca, C, O, P, Na, and Mg elements, and the Ca/P ratios ranged from 1.53 to 1.56. X-ray diffraction (XRD) patterns exhibited peaks characteristic of hydroxyapatite. The results of this study demonstrated that the addition of NaCas induced the formation of vaterite microspheres which possesses an enhanced apatite formation after soaking in SBF at 37 °C for 5 and 10 days. These NaCas-CaCO3 microspheres may be a potential biomaterial for bone regeneration.

  8. Calcium

    MedlinePLUS

    ... you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with soft bones that you eat, such as canned sardines and salmon Calcium-enriched foods such as breakfast ... tofu. Check the product labels. The exact amount of calcium you need ...

  9. Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy.

    PubMed

    Houston, Jacqueline R; Maxwell, Robert S; Carroll, Susan A

    2009-01-01

    Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline calcium (alumino-)silicate hydrate (Al-CSH) forms as a precursor solid to the cement mineral tobermorite. Rate constants for tobermorite growth were found to be k = 0.6 (+/- 0.1) x 10(-5) s(-1) for a solution:solid of 10:1 and 1.6 (+/- 0.8) x 10(-4) s(-1) for a solution:solid of 5:1 (batch mode; T = 150 degrees C). This data indicates that reaction rates for tobermorite growth are faster when the solution volume is reduced by half, suggesting that rates are dependent on solution saturation and that the Gibbs free energy is the reaction driver. However, calculated solution saturation indexes for Al-CSH and tobermorite differ by less than one log unit, which is within the measured uncertainty. Based on this data, we consider both heterogeneous nucleation as the thermodynamic driver and internal restructuring as possible mechanistic pathways for growth. We also use NMR spectroscopy to characterize the site symmetry and bonding environment of Al and Si in a reacted tobermorite sample. We find two [4]Al coordination structures at delta iso = 59.9 ppm and 66.3 ppm with quadrupolar product parameters (PQ) of 0.21 MHz and 0.10 MHz (+/- 0.08) from 27Al 3Q-MAS NMR and speculate on the Al occupancy of framework sites by probing the protonation environment of Al metal centers using 27Al{1H}CP-MAS NMR. PMID:19144195

  10. Gd3+ and calcium sensitive, sodium leak currents are features of weak membrane-glass seals in patch clamp recordings.

    PubMed

    Boone, Adrienne N; Senatore, Adriano; Chemin, Jean; Monteil, Arnaud; Spafford, J David

    2014-01-01

    The properties of leaky patch currents in whole cell recording of HEK-293T cells were examined as a means to separate these control currents from expressed sodium and calcium leak channel currents from snail NALCN leak channels possessing both sodium (EKEE) and calcium (EEEE) selectivity filters. Leak currents were generated by the weakening of gigaohm patch seals by artificial membrane rupture using the ZAP function on the patch clamp amplifier. Surprisingly, we found that leak currents generated from the weakened membrane/glass seal can be surprisingly stable and exhibit behavior that is consistent with a sodium leak current derived from an expressible channel. Leaky patch currents differing by 10 fold in size were similarly reduced in size when external sodium ions were replaced with the large monovalent ion NMDG+. Leaky patch currents increased when external Ca2+ (1.2 mM) was lowered to 0.1 mM and were inhibited (>40% to >90%) with 10 µM Gd3+, 100 µM La3+, 1 mM Co2+ or 1 mM Cd2+. Leaky patch currents were relatively insensitive (<30%) to 1 mM Ni2+ and exhibited a variable amount of block with 1 mM verapamil and were insensitive to 100 µM mibefradil or 100 µM nifedipine. We hypothesize that the rapid changes in leak current size in response to changing external cations or drugs relates to their influences on the membrane seal adherence and the electro-osmotic flow of mobile cations channeling in crevices of a particular pore size in the interface between the negatively charged patch electrode and the lipid membrane. Observed sodium leak conductance currents in weak patch seals are reproducible between the electrode glass interface with cell membranes, artificial lipid or Sylgard rubber. PMID:24945283

  11. Tolperisone-type drugs inhibit spinal reflexes via blockade of voltage-gated sodium and calcium channels.

    PubMed

    Kocsis, Pál; Farkas, Sándor; Fodor, László; Bielik, Norbert; Thán, Márta; Kolok, Sándor; Gere, Anikó; Csejtei, Mónika; Tarnawa, István

    2005-12-01

    The spinal reflex depressant mechanism of tolperisone and some of its structural analogs with central muscle relaxant action was investigated. Tolperisone (50-400 microM), eperisone, lanperisone, inaperisone, and silperisone (25-200 microM) dose dependently depressed the ventral root potential of isolated hemisected spinal cord of 6-day-old rats. The local anesthetic lidocaine (100-800 microM) produced qualitatively similar depression of spinal functions in the hemicord preparation, whereas its blocking effect on afferent nerve conduction was clearly stronger. In vivo, tolperisone and silperisone as well as lidocaine (10 mg/kg intravenously) depressed ventral root reflexes and excitability of motoneurons. However, in contrast with lidocaine, the muscle relaxant drugs seemed to have a more pronounced action on the synaptic responses than on the excitability of motoneurons. Whole-cell measurements in dorsal root ganglion cells revealed that tolperisone and silperisone depressed voltage-gated sodium channel conductance at concentrations that inhibited spinal reflexes. Results obtained with tolperisone and its analogs in the [3H]batrachotoxinin A 20-alpha-benzoate binding in cortical neurons and in a fluorimetric membrane potential assay in cerebellar neurons further supported the view that blockade of sodium channels may be a major component of the action of tolperisone-type centrally acting muscle relaxant drugs. Furthermore, tolperisone, eperisone, and especially silperisone had a marked effect on voltage-gated calcium channels, whereas calcium currents were hardly influenced by lidocaine. These data suggest that tolperisone-type muscle relaxants exert their spinal reflex inhibitory action predominantly via a presynaptic inhibition of the transmitter release from the primary afferent endings via a combined action on voltage-gated sodium and calcium channels. PMID:16126840

  12. Role of intracellular calcium and sodium in light adaptation in the retina of the honey bee drone (Apis mellifera, L)

    PubMed Central

    1976-01-01

    In the honey bee drone, the decrease in sensitivity to light of a retinula cell exposed to background illumination was found to be accurately reflected by the difference in amplitude between the initial transient depolarization and the lowest steady depolarization evoked by the background light. It is shown that both the decrease in sensitivity to light and the accompanying drop in potential from the transient to the plateau can be prevented by injecting EGTA intracellularly. A decrease in duration and amplitude of responses to short test flashes such as observed immediately after illumination was found to occur too when Ca or Na, but not K, Li, or Mg injected into dark-adapted retinula cells. Injection of EGTA into a retinula cell maintained a steady state of light adaptation, was found to cause an increase in amplitude and duration of the response to a short test flash, thus producing the effects of dark adaptation. It is suggested that, in the retina of the honey bee drone, an increase in intracellular calcium concentration plays a central role in light adaptation and that an increase in intracellular sodium concentration, resulting from the influx of sodium ions during the responses to light, could lead to this increase in intracellular free calcium. PMID:818341

  13. Role of intracellular calcium and sodium in light adaptation in the retina of the honey bee drone (Apis mellifera, L).

    PubMed

    Bader, C; Baumann, F; Bertrand, D

    1976-04-01

    In the honey bee drone, the decrease in sensitivity to light of a retinula cell exposed to background illumination was found to be accurately reflected by the difference in amplitude between the initial transient depolarization and the lowest steady depolarization evoked by the background light. It is shown that both the decrease in sensitivity to light and the accompanying drop in potential from the transient to the plateau can be prevented by injecting EGTA intracellularly. A decrease in duration and amplitude of responses to short test flashes such as observed immediately after illumination was found to occur too when Ca or Na, but not K, Li, or Mg injected into dark-adapted retinula cells. Injection of EGTA into a retinula cell maintained a steady state of light adaptation, was found to cause an increase in amplitude and duration of the response to a short test flash, thus producing the effects of dark adaptation. It is suggested that, in the retina of the honey bee drone, an increase in intracellular calcium concentration plays a central role in light adaptation and that an increase in intracellular sodium concentration, resulting from the influx of sodium ions during the responses to light, could lead to this increase in intracellular free calcium. PMID:818341

  14. Phylogeny Unites Animal Sodium Leak Channels with Fungal Calcium Channels in an Ancient, Voltage-Insensitive Clade

    PubMed Central

    Liebeskind, Benjamin J.; Hillis, David M.; Zakon, Harold H.

    2012-01-01

    Proteins in the superfamily of voltage-gated ion channels mediate behavior across the tree of life. These proteins regulate the movement of ions across cell membranes by opening and closing a central pore that controls ion flow. The best-known members of this superfamily are the voltage-gated potassium, calcium (Cav), and sodium (Nav) channels, which underlie impulse conduction in nerve and muscle. Not all members of this family are opened by changes in voltage, however. NALCN (NA+ leak channel nonselective) channels, which encode a voltage-insensitive “sodium leak” channel, have garnered a growing interest. This study examines the phylogenetic relationship among Nav/Cav voltage-gated and voltage-insensitive channels in the eukaryotic group Opisthokonta, which includes animals, fungi, and their unicellular relatives. We show that NALCN channels diverged from voltage-gated channels before the divergence of fungi and animals and that the closest relatives of NALCN channels are fungal calcium channels, which they functionally resemble. PMID:22821012

  15. Hydrate modifications of the non-steroidal anti-inflammatory drug diclofenac sodium: Solid-state characterisation of a trihydrate form.

    PubMed

    Bartolomei, Monica; Rodomonte, Andrea; Antoniella, Eleonora; Minelli, Giuliano; Bertocchi, Paola

    2007-11-01

    Diclofenac sodium is a non-steroidal anti-inflammatory drug widely used in painful and inflammatory diseases. It can exist in different hydrate phases. By exposure to different conditions of temperature and relative humidity can be isolated a trihydrate form never described in literature. The methods of preparation of the trihydrate form (named DSH3) were described and its physico-chemical properties were investigated. Data from FTIR spectroscopy, X-ray powder diffraction and thermal analysis were used for identification and characterisation of DSH3 in comparison with the anhydrous form (DS, the commercial form) and the hydrate form DSH (obtained by exposure of DS to relative humidity even below 60% and already described and characterised in a previous article of the same authors). Intrinsic dissolution studies were performed to compare the pharmaceutical properties of DS and DSH with DSH3, since this form was accidentally found on the Italian market as active pharmaceutical ingredient (API). This work stresses the importance of assessing the correct crystalline form also in API of well-established use to guarantee quality, safety and efficacy of the final dosage form. Furthermore, this study suggests that isomorphic hydrate forms with a different dislocation of water within the crystal structures can exist. PMID:17709225

  16. Vinpocetine blockade of sodium channels inhibits the rise in sodium and calcium induced by 4-aminopyridine in synaptosomes.

    PubMed

    Sitges, María; Galván, Emilio; Nekrassov, Vladimir

    2005-06-01

    The objective of this study was to get a more understandable picture of the mechanism underlying the anticonvulsant action of vinpocetine. The question of how the cerebral excitability is affected was investigated by determining the effect of vinpocetine on the changes on the internal concentrations of Na(+) (Na(i)) and Ca(2+) (Ca(i)) induced by different concentrations of the convulsing agent 4-aminopyridine (4-AP) in striatal isolated nerve endings. The cytosolic concentrations of Na(i) and Ca(i) were detected fluorimetrically with sodium-binding benzofuran isophthalate (SBFI) and fura-2, respectively. Vinpocetine, like the Na(+) channel blocker, tetrodotoxin, abolished the increase in Na(i) induced by 0.1 mM 4-AP and only inhibited in 30% the rise in Na(i) induced by 1mM 4-AP. In contrast with the different sensitivity of the rise in Na(i) induced by 0.1 and 1mM 4-AP to vinpocetine and tetrodotoxin, the rise in Ca(i) induced by the two concentrations of 4-AP was markedly inhibited by vinpocetine (and tetrodotoxin), indicating that only the voltage-sensitive sodium channels (VSSC)-mediated fraction of the rise in Na(i) induced by 4-AP is linked with the activation of pre-synaptic Ca(2+) channels. The elevation of Ca(2+) induced by high K(+) (30 mM) does not require a Na(+) gradient and is vinpocetine and tetrodotoxin insensitive. In contrast, the elevation of Ca(i) induced by 4-AP, requires a physiological (out/in) Na(+) gradient and is vinpocetine and tetrodotoxin-sensitive. It is concluded that by blocking the tetrodotoxin-sensitive fraction of the rise in Na(i) induced by 4-AP, vinpocetine inhibits the concomitant rise in Ca(i) induced by 4-AP. The inhibitory effect of vinpocetine on pre-synaptic voltage-sensitive sodium channels may underlie the in vivo anticonvulsant action of vinpocetine. PMID:15843047

  17. Calcium

    MedlinePLUS

    ... prevent falls in women, but not in men. Metabolic syndrome. Some evidence suggests that getting more calcium from ... vitamin D, might lower the risk of developing metabolic syndrome. Cancer. Research shows that healthy older women who ...

  18. Influence of Pyrethroid Insecticides on Sodium and Calcium Influx in Neocortical Neurons

    EPA Science Inventory

    Pyrethroid insecticides bind to voltage-gated sodium channels and modify their gating kinetics, thereby disrupting neuronal function. Using murine neocortical neurons in primary culture, we have compared the ability of 11 structurally diverse pyrethroid insecticides to evoke Na+ ...

  19. The substitution of sodium for calcium in the mineral nutrition of cotton 

    E-print Network

    Whitenberg, David Calvin

    1959-01-01

    the -Ca -Na plants weighed 75. 4 grams. Unfortunately, the iinal replication of the -Ca -Na treatment of the Deltapine 10 variety was lost in the forty-five-day old plants. Because of this, no valid conclusions can be made concerning the trends... plants contained a higher concentration of calcium than the -Ca -Na plants at the final harvest, however. At that time the control plants exhibited a concentration of 112. 4 milliequivalents of calcium per 100 grams of dry tissue as compared to 135. 7...

  20. Interactions of Organic Additives with Ionic Crystal Hydrates

    NASA Astrophysics Data System (ADS)

    Füredi-Milhofer, H.; Sikiri?, M.; Tunik, L.; Filipovi?-Vincekovi?, N.; Garti, N.

    The interactions of two groups of hydrated model crystals, calcium hydrogenphosphate dihydrate (DCPD) vs. octacalcium phosphate (OCP) and calcium oxalate monohydrate (COM) vs. calcium oxalate dihydrate (COD) with different organic additives are considered. DCPD precipitates as platelet-like crystals with the dominant faces shielded by hydrated layers and charged lateral faces. In the second system COM has charged surfaces, while all faces of COD are covered with layers containing water molecules. The organic molecules tested include negatively charged, flexible and rigid small and macromolecules (glutamic and aspartic acid, citrate, hexaammonium polyphosphate, phytate and polyaspartate) and anionic surfactants (sodium dodecyl sulphate, SDS, sodium diisooctyl sulfosuccinate, AOT, sodium cholate NaC and disodium oleoamido PEG-2 sulfosuccinate, PEG). Two types of effects have been demonstrated: (1) Effect on crystal growth morphology: Flexible organic molecules with high charge density and anionic surfactants affected the growth morphology of DCPD and COM by selectively interacting with the charged lateral faces while rigid molecules (phytate, polyaspartate) specifically recognized the dominant (010) face of DCPD due to structural and stereochemical compatibility. (2) Effect on phase composition: Anionic surfactants at concentrations above the cmc promoted growth of OCP and COD respectively by selectively adsorbing at, and inhibiting growth oif nuclei of DCPD and/or COM, which were dominant in the respective control systems. The effect was especially pronounced in the calcium oxalate precipitation system, where in some cases complete reversal of the phase composition occurred. The important role of the hydrated layer, as part of the structure of the investigated crystal hydrates, in the above crystal additive interactions is discussed.

  1. Models of thermospheric sodium, calcium and magnesium at the magnetic equator

    Microsoft Academic Search

    William J McNeil; Shu T Lai; Edmond Murad

    1998-01-01

    In attempting to interpret recent observations of metals in the lower thermosphere, we have developed several comprehensive models. These models explicitly include the deposition of the metal atoms from ablation of cosmic dust, time-dependant chemical reactions, and transport both by diffusion and by electric fields. The modeling presented here focuses on the depletion of the mesospheric column density of calcium

  2. Solid-state {sup 27}Al and {sup 29}Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

    SciTech Connect

    Pena, P.; Rivas Mercury, J.M. [Instituto de Ceramica y Vidrio, C.S.I.C., C/ Kelsen, 5, 28049 Cantoblanco-Madrid (Spain); Aza, A.H. de [Instituto de Ceramica y Vidrio, C.S.I.C., C/ Kelsen, 5, 28049 Cantoblanco-Madrid (Spain)], E-mail: aaza@icv.csic.es; Turrillas, X. [Instituto de Ciencias de la Construccion Eduardo Torroja, C.S.I.C., C/ Serrano Galvache, 4, 28032 Madrid (Spain); Sobrados, I.; Sanz, J. [Instituto de Ciencia de Materiales, C.S.I.C., C/ Sor Juana Ines de la Cruz, 3, 28049 Cantoblanco-Madrid (Spain)

    2008-08-15

    Partially deuterated Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub y}(OH){sub 12-4y}-Al(OH){sub 3} mixtures, prepared by hydration of Ca{sub 3}Al{sub 2}O{sub 6} (C{sub 3}A), Ca{sub 12}Al{sub 14}O{sub 33} (C{sub 12}A{sub 7}) and CaAl{sub 2}O{sub 4} (CA) phases in the presence of silica fume, have been characterized by {sup 29}Si and {sup 27}Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca{sub 3}Al{sub 2}(OH){sub 12} and Al(OH){sub 3} phases were detected. From the quantitative analysis of {sup 27}Al NMR signals, the Al(OH){sub 3}/Ca{sub 3}Al{sub 2}(OH){sub 12} ratio was deduced. The incorporation of Si into the katoite structure, Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-x}(OH){sub 4x}, was followed by {sup 27}Al and {sup 29}Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of {sup 27}Al MAS-NMR components associated with Al(OH){sub 6} and Al(OSi)(OH){sub 5} environments. The {sup 29}Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From {sup 29}Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures. - Graphical abstract: Transmission electron micrograph of CaAl{sub 2}O{sub 4}-microsilica mixture hydrated at 90 deg. C for 31 days showing a cubic Ca{sub 3}Al{sub 2.0{+-}}{sub 0.2}(SiO{sub 4}){sub 0.9{+-}}{sub 0.2}(OH){sub 1.8} crystal surrounded by unreacted amorphous silica spheres.

  3. Use of Calcium, Potassium, and Sodium Lactates to Control Germination and Outgrowth of Clostridium perfringens Spores during Chilling of Injected Pork

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inhibition of Clostridium perfringens spore germination and outgrowth by calcium (CaL), potassium (KL) or sodium (NaL) lactate in injected pork during abusive chilling regimes was investigated. Lactates (Ca, K, or Na) were incorporated into injected pork at various concentrations (1.0, 2.0, 3.0 and...

  4. Pilot Study of Bioaccumulation and Distribution of Cesium, Potassium, Sodium and Calcium in King Oyster Mushroom (Pleurotus Eryngii) Grown Under Controlled Conditions

    Microsoft Academic Search

    Gra?yna Bystrzejewska-Piotrowska; Dariusz Pianka; Micha? A. Baza?a; Romuald St?borowski; José L. Manjón; Pawel L. Urban

    2008-01-01

    This pilot study presents preliminary results on interrelations between alkali and alkaline earth elements during their transfer to mycelium and fruitbodies of saprophytic fungi. The accumulation and distribution of four elements (cesium, potassium, sodium, and calcium) was evaluated in king oyster mushroom (Pleurotus eryngii) cultivated under controlled conditions. Elemental composition of caps, stipes, and the substrate was analyzed by atomic

  5. Propionic Acid, Sodium Propionate and Calcium Propionate as Inhibitors of Mold Growth. II. Studies Pertaining to the Active Agent Responsible for the Inhibitory Effect of the Propionates

    Microsoft Academic Search

    J. C. Olson Jr.; H. Macy

    1946-01-01

    Recent studies (4, 9, 11) have shown that aqueous solutions of sodium or calcium propionate, when used in treating parchment paper for wrapping prints of butter, were effective in restraining the growth of mold on the butter surface. Investigators in several branches of biology have been interested in the action of organic acids and their ~alts on microorganisms and many.

  6. Changes in Sodium, Calcium, and Magnesium Ion Concentrations That Inhibit Geobacillus Biofilms Have No Effect on Anoxybacillus flavithermus Biofilms.

    PubMed

    Somerton, B; Lindsay, D; Palmer, J; Brooks, J; Flint, S

    2015-08-01

    This study investigated the effects of varied sodium, calcium, and magnesium concentrations in specialty milk formulations on biofilm formation by Geobacillus spp. and Anoxybacillus flavithermus. The numbers of attached viable cells (log CFU per square centimeter) after 6 to 18 h of biofilm formation by three dairy-derived strains of Geobacillus and three dairy-derived strains of A. flavithermus were compared in two commercial milk formulations. Milk formulation B had relatively high sodium and low calcium and magnesium concentrations compared with those of milk formulation A, but the two formulations had comparable fat, protein, and lactose concentrations. Biofilm formation by the three Geobacillus isolates was up to 4 log CFU cm(-2) lower in milk formulation B than in milk formulation A after 6 to 18 h, and the difference was often significant (P ? 0.05). However, no significant differences (P ? 0.05) were found when biofilm formations by the three A. flavithermus isolates were compared in milk formulations A and B. Supplementation of milk formulation A with 100 mM NaCl significantly decreased (P ? 0.05) Geobacillus biofilm formation after 6 to 10 h. Furthermore, supplementation of milk formulation B with 2 mM CaCl2 or 2 mM MgCl2 significantly increased (P ? 0.05) Geobacillus biofilm formation after 10 to 18 h. It was concluded that relatively high free Na(+) and low free Ca(2+) and Mg(2+) concentrations in milk formulations are collectively required to inhibit biofilm formation by Geobacillus spp., whereas biofilm formation by A. flavithermus is not impacted by typical cation concentration differences of milk formulations. PMID:26002898

  7. The hydrothermal decomposition of calcium monosulfoaluminate 14-hydrate to katoite hydrogarnet and beta-anhydrite: An in-situ synchrotron X-ray diffraction study

    SciTech Connect

    Meller, Nicola; Kyritsis, Konstantinos [School of Engineering and Centre for Science at Extreme Conditions, University of Edinburgh, The King's Buildings, Edinburgh EH9 3JZ (United Kingdom); Hall, Christopher, E-mail: christopher.hall@ed.ac.u [School of Engineering and Centre for Science at Extreme Conditions, University of Edinburgh, The King's Buildings, Edinburgh EH9 3JZ (United Kingdom)

    2009-10-15

    We apply in-situ synchrotron X-ray diffraction to study the transformation of calcium monosulfoaluminate 14-hydrate Ca{sub 4}Al{sub 2}O{sub 6}(SO{sub 4}).14H{sub 2}O [monosulfate-14] to hydrogarnet Ca{sub 3}Al{sub 2}(OH){sub 12} on the saturated water vapor pressure curve up to 250 deg. C. We use an aqueous slurry of synthetic ettringite Ca{sub 6}Al{sub 2}(SO{sub 4}){sub 3}(OH){sub 12}.26H{sub 2}O as the starting material; on heating, this decomposes at about 115 deg. C to form monosulfate-14 and bassanite CaSO{sub 4}.0.5H{sub 2}O. Above 170 deg. C monosulfate-14 diffraction peaks slowly diminish in intensity, perhaps as a result of loss of crystallinity and the formation of an X-ray amorphous meta-monosulfate. Hydrogarnet nucleates only at temperatures above 210 deg. C. Bassanite transforms to beta-anhydrite (insoluble anhydrite) at about 230 deg. C and this transformation is accompanied by a second burst of hydrogarnet growth. The transformation pathway is more complex than previously thought. The mapping of the transformation pathway shows the value of rapid in-situ time-resolved synchrotron diffraction. - Graphical abstract: We use in-situ synchrotron diffraction to observe the decomposition of layer compound calcium monosulfoaluminate 14-hydrate (left) to form hydrogarnet (right)and beta-anhydrite under hydrothermal conditions.

  8. The characterization of hardened alkali-activated blast-furnace slag pastes and the nature of the calcium silicate hydrate (C-S-H) phase

    SciTech Connect

    Richardson, I.G.; Brough, A.R.; Groves, G.W.; Dobson, C.M. (Univ. of Oxford (United Kingdom))

    1994-01-01

    Calcium silicate hydrate (C-S-H) gel is the principal binding phase in hardened OPC pastes and concretes, and also when the OPC has been partially replaced by pozzolanic by-products such as ground granulated blast-furnace slag (GGBFS) and pulverized fuel ash. The C-S-H gels present in commercial blast-furnace slag and synthetic-slag glass pastes produced by hydrating with 5M KOH solution have been studied by a combination of transmission electron microscopy (TEM) and [sup 29]Si and [sup 27]Al nuclear magnetic resonance (NMR) spectroscopy. They are related by both composition and morphology to the C-S-H gels present in slag-OPC paste but are more crystalline. The inner product C-S-H is intermixed on a fine scale with a Mg,Al-rich phase with a Mg/Al ratio of [approximately]2.5. The C-S-H in both inner and outer product contains substituted Al in tetrahedral co-ordination sites. The data are analyzed in terms of a model for the structure of C-S-H gel.

  9. Voltage-dependent calcium block of normal and tetramethrin-modified single sodium channels.

    PubMed Central

    Yamamoto, D; Yeh, J Z; Narahashi, T

    1984-01-01

    The mechanisms by which external Ca ions block sodium channels were studied by a gigaohm seal patch clamp method using membranes excised from N1E-115 neuroblastoma cells. Tetramethrin was used to prolong the open time of single channels so that the current-voltage relationship could be readily determined over a wide range of membrane potentials. Comparable experiments were performed in the absence of tetramethrin. Increasing external Ca ions from 0.18 to 9.0 mM reduced the single channel conductance without causing flickering. From the dose-response relation the dissociation constant for Ca block at 0 mV was estimated to be 32.4 +/- 1.05 mM. The block was intensified by hyperpolarization. The voltage dependence indicates that Ca ions bind to sodium channels at a site located 37 +/- 2% of the electrical distance from the outside. The current increased with increasing external Na concentrations but showed a saturation; the concentration for half-maximal saturation was estimated to be 185 mM at -50 mV and 204 mM at 0 mV. A model consisting of a one-ion pore with four barriers and three wells can account for the observations that deviate from the independence principle, namely, the saturation of current, block by Ca ions, and rectification in current-voltage relationship. The results suggest that the Ca-induced decrease of the macroscopic sodium current results from a reduced single sodium channel conductance. PMID:6324913

  10. Histrionicotoxins: Effects on binding of radioligands for sodium, potassium, and calcium channels in brain membranes

    Microsoft Academic Search

    T. Lovenberg; J. W. Daly

    1986-01-01

    A series of eight histrionicotoxins and two synthetic analogs inhibit binding of [3H]batrachotoxinin B to sites on voltage dependent sodium channels in brain membranes. Perhydrohistrionicotoxin (IC50 0.33 µM) and octahydrohistrionicotoxin (IC50 1.2 µM) are comparable in activities to potent local anesthetics. Histrionicotoxin (IC50 17 µM) and the other histrionicotoxins are much less potent. The histrionicotoxins also inhibit binding of [3H]phencyclidine

  11. 2010 Minerals Yearbook U.S. Department of the Interior

    E-print Network

    calcium borate), kernite (hydrated sodium borate), tincal, and ulexite (hydrated sodium calcium borate, the calcium borate colemanite, and the sodium-calcium borate ulexite. Borate deposits are associated

  12. Combination of sodium chlorite and calcium propionate reduces enzymatic browning and microbial population of fresh-cut "Granny Smith" apples.

    PubMed

    Guan, Wenqiang; Fan, Xuetong

    2010-03-01

    Tissue browning and microbial growth are the main concerns associated with fresh-cut apples. In this study, effects of sodium chlorite (SC) and calcium propionate (CP), individually and combined, on quality and microbial population of apple slices were investigated. "Granny Smith" apple slices, dipped for 5 min in CP solutions at 0%, 0.5%, 1%, and 2% (w/v) either alone or in combination with 0.05% (w/v) SC, were stored at 3 and 10 degrees C for up to 14 d. Color, firmness, and microflora population were measured at 1, 7, and 14 d of storage. Results showed that CP alone had no significant effect on the browning of cut apples. Even though SC significantly inhibited tissue browning initially, the apple slices turned brown during storage at 10 degrees C. The combination of CP and SC was able to inhibit apple browning during storage. Samples treated with the combination of SC with CP did not show any detectable yeast and mold growth during the entire storage period at 3 degrees C. At 10 degrees C, yeast and mold count increased on apple slices during storage while CP reduced the increase. However, high concentrations of CP reduced the efficacy of SC in inactivating E. coli inoculated on apples. Overall, our results suggested that combination of SC with 0.5% and 1% CP could be used to inhibit tissue browning and maintain firmness while reducing microbial population. Practical Application: Apple slices, which contain antioxidants and other nutrient components, have emerged as popular snacks in food service establishments, school lunch programs, and for family consumption. However, the further growth of the industry is limited by product quality deterioration caused by tissue browning, short shelf-life due to microbial growth, and possible contamination with human pathogens during processing. Therefore, this study was conducted to develop treatments to reduce microbial population and tissue browning of "Granny Smith" apple slices. Results showed that an antimicrobial compound, sodium chlorite, is effective in not only eliminating microbes but also inhibiting tissue browning of apple slices. However, the compound caused tissue softening and its antibrowning effect was short-lived, lasting only for a few days. Combination of the compound with a calcium-containing food additive was able to improve firmness and freshness of apple slices while reducing population of Escherichia coli artificially inoculated on samples and inhibiting the growth of yeast and mold during storage. PMID:20492244

  13. EFFECTS OF DIFFERENT CALCIUM FORMS ON GAS EXCHANGE ACTIVITIES, WATER USAGE AND MACRONUTRIENT UPTAKE BY STRAWBERRY PLANTS UNDER SODIUM CHLORIDE STRESS

    Microsoft Academic Search

    M. Khayyat; S. Khanizadeh; E. Tafazoli; S. Rajaee; B. Kholdebarin; Y. Emam

    2011-01-01

    Strawberry cv. ‘Selva’ was grown in soilless culture under greenhouse conditions to study the effects of supplementary calcium added to nutrient solution and applied to the plants grown under sodium chloride (NaCl) (35 mM) salinity. Treatments were: 1) commercial nutrient solution or control [expressed as (N)]; 2) N+NaCl (35 mM) [expressed as (NS)]; 3) NS+CaCl2 (5 mM) [expressed as (NS1)];

  14. Effect of Sodium and Calcium Carbonates on Milk Production and Composition of Milk, Blood, and Rumen Contents of Cows Fed Grain Ad Libitum with Restricted Roughage1

    Microsoft Academic Search

    R. S. Emery; L. D. Brown; J. W. Thomas

    1964-01-01

    SUMMARY Six cows were used in a Latin square design consisting of three periods of 28 days each and three treatments, grain plus sodium bicarbonate (1 lb\\/day), grain plus calcium carbonate (0.6 lb\\/day), and grain alone. Roughage was restricted to 2 lb hay\\/day and grain was fed ad libitum. Similarly, two groups of five cows each were used in a

  15. Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

    USGS Publications Warehouse

    Tommasso J.R., Wright, M. I.; Simco, B.A.; Davis, K.B.

    1980-01-01

    Environmental chloride has been shown to inhibit methemoglobin formation in fish, thereby offering a protective effect against nitrite toxicity. Channel catfish (Ictalurus punctatus) were simultaneously exposed to various environmental nitrite and chloride levels (as either CaCl2 or NaCl) in dechlorinated tap water (40 mg/L total hardness, 47 mg/L alkalinity, 4 mg/L chloride, pH = 6.9-7.1, and temperature 21-24°C). Methemoglobin levels in fish simultaneously exposed to 2.5 mg/L nitrite and up to 30 mg/L chloride as either CaCl2 or NaCl were similar but significantly lower than in unprotected fish. Exposure to 10 mg/L nitrite and 60 mg/L chloride resulted in methemoglobin levels similar to those of the controls; most unprotected fish died. Fish exposed to 10 mg/L nitrite had significantly lower methemoglobin levels when protected with 15.0 mg/L chloride as CaCl2 than with NaCl. Fish exposed to nitrite in the presence of 60 mg/L chloride (as either CaCl2 or NaCl) had similar 24-h LC50 values that were significantly elevated above those obtained in the absence of chloride. Calcium had little effect on tolerance to nitrite toxicity in channel catfish in contrast to its large effect reported in steelhead trout (Salmo gairdneri).

  16. Conditional knockout of smooth muscle sodium calcium exchanger type?1 lowers blood pressure and attenuates Angiotensin II?salt hypertension

    PubMed Central

    Wang, Youhua; Chen, Ling; Li, Meng; Cha, Helen; Iwamoto, Takahiro; Zhang, Jin

    2015-01-01

    Abstract The functions of smooth muscle sodium calcium exchanger (NCX) in the vasculature are controversial and poorly understood. To determine the possible roles of NCX in the vascular phenotype and function, we developed a novel mouse model (SM?NCX1 KO) in which the smooth muscle?specific NCX type?1 (NCX1) was conditionally knocked out using tamoxifen?inducible Cre?loxP recombination technique. SM?NCX1 KO mice exhibit significantly lower blood pressure and attenuated angiotensin II (Ang II)?salt?induced hypertension (measured by radio telemetry and intra?arterial catheterization). Isolated, pressurized mesenteric small resistance arteries from SM?NCX1 KO mice, compared to control arteries, were characterized by the following: (1) ~90% reduced NCX1 protein expression; (2) impaired functional responses to (i) acute NCX inhibition by SEA0400 or SN?6, (ii) NCX activation by low [Na+]o, and (iii) Na+ pump inhibition by ouabain; (3) attenuated myogenic reactivity; and (4) attenuated vasoconstrictor response to phenylephrine but not Ang II. These results provided direct evidence that arterial NCX1 normally mediates net Ca2+ influx that helps maintain basal vascular tone in small resistance arteries and blood pressure under physiological conditions. Importantly, NCX1 contributes to blood pressure elevation in Ang II?salt hypertension, possibly by regulating ??adrenergic receptor activation. PMID:25626872

  17. A preliminary study of enamel remineralization by dentifrices based on Recalden (CPP-ACP) and Novamin (calcium-sodium-phosphosilicate).

    PubMed

    Gjorgievska, Elizabeta S; Nicholson, John W

    2010-01-01

    The purpose of this study was to investigate the enamel remineralization potential of two toothpastes, one of which was based on Recaldent (CPP- ACP) and the other on NovaMin (Calcium-sodium-phosphosilicate). Human permanent molar teeth were subjected to three consecutive demineralization cycles. These cycles were followed by remineralization of the experimental groups by toothpastes containing Recalden and NovaMin respectively. The samples were analyzed by Scanning Electron Microscope, (SEM) and energy-dispersive X-ray spectroscopy analysis (EDX). Extensive demineralization was noted in the control group (without remineralization) while the groups treated with the dentifices demonstrated various degrees of remineralization, as shown by formation of different types of deposits on the enamel surface. The EDX analysis showed increased amounts of Ca, P Si and Zn in the enamel of the experimental groups, compared to the control one. Toothpastes containing Recalden and especially NovaMin have the potential to remineralize enamel, a property which might be important in finding a substitute to pit and fissure sealing. PMID:21638965

  18. Calcium H & K and sodium D absorption induced by the interstellar and circumgalactic media of the Milky Way

    E-print Network

    Murga, Maria; Ménard, Brice; Lan, Ting-Wen

    2015-01-01

    We map out calcium II & sodium I absorption (Fraunhofer H, K & D lines) induced by both the interstellar medium and the circumgalactic medium of the Milky Way. Our measurements cover more than $9000$ deg$^2$ and make use of about $300,000$ extragalactic spectra from the Sloan Digital Sky Survey. We present absorption maps for these two species and then compare their distributions to those of neutral hydrogen and dust. We show that the abundance of Na I with respect to neutral hydrogen stays roughly constant in different environments, while that of Ca II decreases with hydrogen column density. Studying how these tracers vary as a function of velocity, we show that, on average, the N(Na I)/N(Ca II) ratio decreases at higher velocity with respect to the local standard of rest, similar to the local Routly-Spitzer effect but seen on Galactic scale. We show that it is likely caused by higher gas/dust density at lower velocity. Finally, we show that Galactic Ca II and Na I absorption needs to be taken into a...

  19. Microstructural, textural, and sensory characteristics of probiotic yogurts fortified with sodium calcium caseinate or whey protein concentrate.

    PubMed

    Akal?n, A S; Unal, G; Dinkci, N; Hayaloglu, A A

    2012-07-01

    The influence of milk protein-based ingredients on the textural characteristics, sensory properties, and microstructure of probiotic yogurt during a refrigerated storage period of 28 d was studied. Milk was fortified with 2% (wt/vol) skim milk powder as control, 2% (wt/vol) sodium calcium caseinate (SCaCN), 2% (wt/vol) whey protein concentrate (WPC) or a blend of 1% (wt/vol) SCaCN and 1% (wt/vol) WPC. A commercial yogurt starter culture and Bifidobacterium lactis Bb12 as probiotic bacteria were used for the production. The fortification with SCaCN improved the firmness and adhesiveness. Higher values of viscosity were also obtained in probiotic yogurts with SCaCN during storage. However, WPC enhanced water-holding capacity more than the caseinate. Addition of SCaCN resulted in a coarse, smooth, and more compact protein network; however, WPC gave finer and bunched structures in the scanning electron microscopy micrographs. The use of SCaCN decreased texture scores in probiotic yogurt; probably due to the lower water-holding capacity and higher syneresis values in the caseinate-added yogurt sample. Therefore, the textural characteristics of probiotic yogurts improved depending on the ingredient variety. PMID:22720919

  20. A graphene loading heterogeneous hydrated forms iron based fluoride nanocomposite as novel and high-capacity cathode material for lithium/sodium ion batteries

    NASA Astrophysics Data System (ADS)

    Shen, Yongqiang; Wang, Xianyou; Hu, Hai; Jiang, Miaoling; Yang, Xiukang; Shu, Hongbo

    2015-06-01

    A graphene loading heterogeneous hydrated forms iron based fluoride (abbreviated as FeF3·xH2O/G) nanocomposite is successfully designed and synthesized for the first time by a sol-gel method. It found that the FeF3·xH2O nanoparticles distribute randomly on the surface of the graphene, stacking together to form a nanocomposite with high specific surface and abundant mesporous structure. The FeF3·xH2O was consisted of FeF3·3H2O and FeF2.5·0.5H2O with pyrochlore phase structure and FeF3·0.33H2O with hexagonal-tungsten-bronze-type structure (HTB). The FeF3·xH2O/G was used as cathode materials of rechargeable lithium/sodium batteries, respectively. It has been found that it can deliver a large reversible capacity exceeding 200 mAh g-1 and excellent cyclic performance with a residual capacity of 183 mAh g-1 after 100 cycles at 0.2C and 149 mAh g-1 after 200 cycles at 1C, especially, an outstanding rate performance exceeding 130 mAh g-1 at 5C in the voltage range of 1.5-4.5 V for Li-ion batteries. Moreover, when FeF3·xH2O/G is used as cathode material of Na-ion batteries, it exhibits also a high reversible capacity of 101 mAh g-1 after 30 cycles in the voltage range of 1.0-4.0 V at 0.1C. Therefore, FeF3·xH2O/G will a promising cathode material for high-performance lithium/sodium ion batteries.

  1. The hydrothermal decomposition of calcium monosulfoaluminate 14-hydrate to katoite hydrogarnet and ?-anhydrite: An in-situ synchrotron X-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Meller, Nicola; Kyritsis, Konstantinos; Hall, Christopher

    2009-10-01

    We apply in-situ synchrotron X-ray diffraction to study the transformation of calcium monosulfoaluminate 14-hydrate Ca 4Al 2O 6(SO 4)·14H 2O [monosulfate-14] to hydrogarnet Ca 3Al 2(OH) 12 on the saturated water vapor pressure curve up to 250 °C. We use an aqueous slurry of synthetic ettringite Ca 6Al 2(SO 4) 3(OH) 12·26H 2O as the starting material; on heating, this decomposes at about 115 °C to form monosulfate-14 and bassanite CaSO 4·0.5H 2O. Above 170 °C monosulfate-14 diffraction peaks slowly diminish in intensity, perhaps as a result of loss of crystallinity and the formation of an X-ray amorphous meta-monosulfate. Hydrogarnet nucleates only at temperatures above 210 °C. Bassanite transforms to ?-anhydrite (insoluble anhydrite) at about 230 °C and this transformation is accompanied by a second burst of hydrogarnet growth. The transformation pathway is more complex than previously thought. The mapping of the transformation pathway shows the value of rapid in-situ time-resolved synchrotron diffraction.

  2. Light and Calcium Interactions in Chlorella Inhibited by Sodium Chloride 12

    PubMed Central

    Chimiklis, Phrosene E.; Karlander, Edward P.

    1973-01-01

    Analysis of NaCl toxicity in Chlorella sorokiniana showed decreased growth rates, increased dry weight per cell, increased intracellular Na+ and Cl?, more total chlorophyll per cell, a decreased chlorophyll a to chlorophyll b ratio, increased rates of O2 evolution, and decreased rates of CO2 fixation when the extracellular concentration of NaCl was increased from zero to 0.3 m. Cultures did not grow at concentrations greater than 0.3 m NaCl unless 10 mm calcium salts were present. Inclusion of that concentration of Ca2+ extended the tolerance to 0.5 m NaCl before growth stopped. Increasing the light intensity from 1.2 to 9.4 mw/cm2 increased growth rates for cultures in 0.10 to 0.45 m NaCl. At 14 mw/cm2 added Ca2+ reduced growth rates of cultures in 0.3 m NaCl compared to controls without added Ca2+. Maximal growth rates for cultures in NaCl media were achieved by addition of 10 mm CaSO4 and maintenance of the light intensity at 9.4 mw/cm2. The maximal growth rate of the organism was 9.6 doublings/day achieved at 2.7 mw/cm2 for control cultures. In 0.3 m NaCl the growth rate was 4.3 doublings/day at 2.7 mw/cm2 and 8.2 doublings/day at 9.4 mw/cm2 with 10 mm CaSO4 added. Increasing light intensities from 2.7 to 9.4 to 14 mw/cm2 decreased intracellular Na+ in cells cultured in 0.3 m NaCl medium without added Ca2+ and increased Cl? uptake in cells cultured in 0.3 m NaCl medium with and without added Ca2+. For cells cultured in 0.3 m NaCl medium at 14 mw/cm2 intracellular Na+ was 0.68 meq/g dry weight with Ca2+ added and 0.81 meq/g dry weight without Ca2+ added. Addition of Ca2+ at 2.7 mw/cm2 reduced intracellular Na+ to similar values. It is postulated that energy requirements for active Na+ exclusion were reduced by addition of Ca2+ allowing more energy to be used for cell growth resulting in increased growth rates. O2 evolution and CO2 fixation studies indicated that increased photosynthetic energy, probably actuated by a high proton gradient accompanying Cl? influx and uncoupled from CO2 fixation, was available for maintenance of cellular integrity and active control of intracellular ionic ratios. The O2 evolving capacity was destroyed at 12 and 29 mw/cm2 for cells cultured in 0.3 m NaCl medium respectively with and without the addition of Ca2+. Control cultures continued producing O2 at light intensities up to 115 mw/cm2. PMID:16658295

  3. Effects of sodium bicarbonate and 1,25-dihydroxy-cholecalciferol on calcium and phosphorus balances in the rat

    SciTech Connect

    Goulding, A.; McIntosh, J.; Campbell, D.

    1984-04-01

    Metabolic balance studies were undertaken to determine whether sodium bicarbonate (NaHCO/sub 3/) supplements (4.5 mmol/day) altered 7-day cumulative calcium (Ca) phosphorus (P) balances in growing rats consuming either a basal diet providing 0.6% Ca and 0.3% P, or this diet plus 1,25-dihydroxycholecalciferol (40 ng 1,25(OH)/sub 2/D/sub 3//day). Feeding bicarbonate lowered urinary Ca but raised fecal Ca so that Ca balance became less positive. However, 1,25(OH)/sub 2/D/sub 3/ increased net absorption of Ca and P to the same degree when given to control rats and rats consuming bicarbonate. Nevertheless, bicarbonate-fed rats had lower net Ca absorption than controls, even when treated with high doses of 1,25(OH)/sub 2/D/sub 3/. Changes in net Ca absorption induced by bicarbonate may occur at a point in the gut distal to the duodenum since duodenal /sup 45/Ca absorption was decreased by bicarbonate feeding. The present results show that bicarbonate consumption depressed net Ca absorption in the rat. The effect appears to be independent of changes in 1,25(OH)/sub 2/D/sub 3/ metabolism because it is manifest in animals receiving high doses of 1,25(OH)/sub 2/D/sub 3/, which stimulate alimentary Ca absorption maximally, and because bicarbonate-fed rats are able to respond normally to exogenous 1,25(OH)/sub 2/D/sub 3/ by increasing their net absorption of Ca and P. In view of this demonstration that NaHCO/sub 3/ supplements elevate fecal Ca loss in the rat, it is suggested that studies should be undertaken to determine whether bicarbonate exerts similar adverse effects on Ca balance in humans.

  4. Hydration behaviour of some mono-, di-, and tri-saccharides in aqueous sodium gluconate solutions at (288.15, 298.15, 308.15 and 318.15)K: volumetric and rheological approach.

    PubMed

    Banipal, Parampaul K; Singh, Vickramjeet; Aggarwal, Neha; Banipal, Tarlok S

    2015-02-01

    Thermodynamic and transport properties are very useful in providing valuable information regarding the hydration characteristics of saccharides and play a pivotal role in the study of taste behaviour of saccharides in mixed aqueous solutions. The effects of sodium gluconate and other sodium salts on the hydration behaviour and the basic taste quality of saccharides have been studied from measured apparent molar volumes (V2,?), partial molar volumes (V2(°)) at infinite-dilution, and viscosity B-coefficients, of eight monosaccharides, six disaccharides and two trisaccharides in (0.25, 0.50, 1.00 and 1.50)molkg(-1) aqueous sodium gluconate solutions over a temperature range of (288.15-318.15)K and at atmospheric pressure. Partial molar volumes of transfer (?tV2(°)) and viscosity B-coefficients of transfer (?tB) of saccharides and other parameters such as isobaric expansion coefficients, interaction coefficients (using McMillan-Mayer theory), and dB/dT parameters have also been determined and discussed in terms of solute (saccharide)-cosolute (sodium gluconate) interactions. PMID:25172693

  5. Hydration-Coupled Dynamics in Proteins Studied by Neutron Scattering and NMR: The Case of the Typical EF-Hand Calcium-Binding Parvalbumin

    Microsoft Academic Search

    Jean-Marc Zanotti; Marie-Claire Bellissent-Funel; Joseph Parello

    1999-01-01

    The influence of hydration on the internal dynamics of a typical EF-hand calciprotein, parvalbumin, was investigated by incoherent quasi-elastic neutron scattering (IQNS) and solid-state 13C-NMR spectroscopy using the powdered protein at different hydration levels. Both approaches establish an increase in protein dynamics upon progressive hydration above a threshold that only corresponds to partial coverage of the protein surface by the

  6. Trace Element Analysis as an Exploration Tool for Unconfined Class 2 Hydrate Deposits

    NASA Astrophysics Data System (ADS)

    Johnson, A. D.; Max, M. P.; Osegovic, J. P.; Brazel, L.; Tatro, S.

    2007-12-01

    Hydrate system analysis, analogous to hydrocarbon system analysis, is based on confirming significant gas flux, suitable thickness of hydrate stability zone, and suitably porous and permeable hydrate 'trap' beds in which economically significant hydrate crystallization may take place. Unconfined Class 2 hydrate deposits, which form by crystallization of dissolved natural gas in more porous and permeable sediments whose pore fluids may vent from the seafloor carry the dissolved rejected material. Analysis of superficial pore or vent water may provide a sensitive means of suggesting whether the water was once associated with hydrate crystallization. The rejection of dissolved ions and compounds during carbon dioxide hydrate precipitation on a chilled surface was determined to quantify the reject rate of specific materials from the hydrate matrix. Seawater and seawater doped with boric acid (H3BO3, MW 61.83 g/mol) and sodium borate decahydrate (Na2B4O7*10H2O, MW 381.37 g/mol) were used as crystallization solvents. Initial boron concentrations ranged from 4.1 to 27mg/L. Hydrate formation occurred with significant rejection of boron from the hydrate matrix, increasing the concentration in the crystallizing fluid. The initial boron concentration level did not affect the rejection efficiency, determined by comparing the initial concentration of boron to the concentration in the hydrate melt water. In addition to boron, naturally occurring calcium and magnesium concentration levels were also studied and showed a similar concentration reduction. Our experiments have shown that non-ionic dissolved species that occur in sediment pore water, in which hydrate may form, are rejected and concentrated during hydrate formation. The measurement of NaCl may provide a clue to the water having once been involved in subjacent hydrate formation, but other species that do not have additional crystallization opportunities in the sediment may be better clues to the extent of a hydrate formation. Identification of characteristic indicators of hydrate system participation would allow rapid sampling and analysis of seafloor water samples to be used as an exploration tool.

  7. Sodium/calcium exchanger is upregulated by sulfide signaling, forms complex with the ?1 and ?3 but not ?2 adrenergic receptors, and induces apoptosis.

    PubMed

    Markova, Jana; Hudecova, Sona; Soltysova, Andrea; Sirova, Marta; Csaderova, Lucia; Lencesova, Lubomira; Ondrias, Karol; Krizanova, Olga

    2014-07-01

    Hydrogen sulfide (H2S) as a novel gasotransmitter regulates variety of processes, including calcium transport systems. Sodium calcium exchanger (NCX) is one of the key players in a regulation calcium homeostasis. Thus, the aims of our work were to determine effect of sulfide signaling on the NCX type 1 (NCX1) expression and function in HeLa cells, to investigate the relationship of ?-adrenergic receptors with the NCX1 in the presence and/or absence of H2S, and to determine physiological importance of this potential communication. As a H2S donor, we used morpholin-4-ium-4-methoxyphenyl(morpholino) phosphinodithioate-GYY4137. We observed increased levels of the NCX1 mRNA, protein, and activity after 24 h of GYY4137 treatment. This increase was accompanied by elevated cAMP due to the GYY4137 treatment, which was completely abolished, when NCX1 was silenced. Increased cAMP levels would point to upregulation of ?-adrenergic receptors. Indeed, GYY4137 increased expression of ?1 and ?3 (but not ?2) adrenergic receptors. These receptors co-precipitated, co-localized with the NCX1, and induced apoptosis in the presence of H2S. Our results suggest that sulfide signaling plays a role in regulation of the NCX1, ?1 and ?3 adrenergic receptors, their co-localization, and stimulation of apoptosis, which might be of a potential importance in cancer treatment. PMID:24114174

  8. The effect of casein phosphopeptide-amorphous calcium phosphate paste and sodium fluoride mouthwash on the prevention of dentine erosion: An in vitro study

    PubMed Central

    Moezizadeh, Maryam; Alimi, Azar

    2014-01-01

    Aim: The purpose was to compare the effect of 0.2% sodium fluoride mouthwash and casein phosphopeptide-amorphous calcium phosphate paste on prevention of dentin erosion. Materials and Methods: Buccal surfaces of 36 sound premolar teeth were ground flat and polished with abrasive discs. Half the polished surfaces were covered with tape to maintain a reference surface. Samples were randomly allocated into three groups. Group A was pretreated with tooth mousse (TM) 4 times a day for 5 days. Group B was pretreated with 0.2% sodium fluoride mouthwash 4 times a day for 5 days. Group C was considered as the control group with no pretreatment. In the next step, the samples were exposed to Coca-Cola 4 times a day for 3 days. After each erosive cycle, the samples were rinsed with deionized water and stored in artificial saliva. The surface loss was determined using profilometry. Results: The erosion in both Groups A and B was less than the control group. The surface loss in mouthwash group was significantly lower than in the control group. Erosion in TM group was more than the mouthwash group and less than the control group. Conclusion: Sodium fluoride mouthwash is more effective for prevention of dentin erosion. PMID:24944448

  9. Hydration-coupled dynamics in proteins studied by neutron scattering and NMR: the case of the typical EF-hand calcium-binding parvalbumin.

    PubMed Central

    Zanotti, J M; Bellissent-Funel, M C; Parello, J

    1999-01-01

    The influence of hydration on the internal dynamics of a typical EF-hand calciprotein, parvalbumin, was investigated by incoherent quasi-elastic neutron scattering (IQNS) and solid-state 13C-NMR spectroscopy using the powdered protein at different hydration levels. Both approaches establish an increase in protein dynamics upon progressive hydration above a threshold that only corresponds to partial coverage of the protein surface by the water molecules. Selective motions are apparent by NMR in the 10-ns time scale at the level of the polar lysyl side chains (externally located), as well as of more internally located side chains (from Ala and Ile), whereas IQNS monitors diffusive motions of hydrogen atoms in the protein at time scales up to 20 ps. Hydration-induced dynamics at the level of the abundant lysyl residues mainly involve the ammonium extremity of the side chain, as shown by NMR. The combined results suggest that peripheral water-protein interactions influence the protein dynamics in a global manner. There is a progressive induction of mobility at increasing hydration from the periphery toward the protein interior. This study gives a microscopic view of the structural and dynamic events following the hydration of a globular protein. PMID:10233057

  10. Adsorption of polyelectrolytes and its influence on the rheology, zeta potential, and microstructure of various cement and hydrate phases

    Microsoft Academic Search

    Anatol Zingg; Frank Winnefeld; Lorenz Holzer; Joachim Pakusch; Stefan Becker; Ludwig Gauckler

    2008-01-01

    In this study the influence of polycarboxylate-based polyelectrolytes on the particle interaction among tricalcium silicate (C3S, main clinker phase), calcium silicate hydrates (CSH), and calcium aluminate sulfate hydrates (ettringite) (main hydration phases) has been examined. These phases are the constituents of major concern during early hydration of cement suspensions. The results of zeta potential measurements on single mineral phase experiments

  11. Circadian models of serum potassium, sodium, and calcium concentrations in healthy individuals and their application to cardiac electrophysiology simulations at individual level.

    PubMed

    Fijorek, Kamil; Puskulluoglu, Miroslawa; Polak, Sebastian

    2013-01-01

    In the article a brief description of the biological basis of the regulation of human biological clocks was presented in order to introduce the role of circadian rhythms in physiology and specifically in the pharmacological translational tools based on the computational physiology models to motivate the need to provide models of circadian fluctuation in plasma cations. The main aim of the study was to develop statistical models of the circadian rhythm of potassium, sodium, and calcium concentrations in plasma. The developed ion models were further tested by assessing their influence on QT duration (cardiac endpoint) as simulated by the biophysically detailed models of human left ventricular cardiomyocyte. The main results are model equations along with an electronic supplement to the article that contains a fully functional implementation of all models. PMID:24078832

  12. Determination of ammonium, calcium, magnesium, potassium and sodium in drinking waters by capillary zone electrophoresis on a column-coupling chip.

    PubMed

    Masár, Marián; Sydes, Daniel; Luc, Milan; Kaniansky, Dusan; Kuss, Heinz-Martin

    2009-08-21

    This work deals with simultaneous determination of ammonium, calcium, magnesium, sodium and potassium in drinking waters by capillary zone electrophoresis (CZE) on a column-coupling (CC) chip with suppressed hydrodynamic and electroosmotic transports. CZE separations were carried out in a propionate background electrolyte at a low pH (3.2) containing 18-crown-6-ether (18-crown-6) to reach a complete resolution of the cations. In addition, triethylenetetramine (TETA) coated the inner wall surface of the chip channels. The concentration limits of detection (cLOD) for the studied cations ranged from 4.9 to 11.5 microg/l concentrations using a 900 nl volume of the sample injection channel. 93-106% recoveries of the cations in drinking waters indicate a good predisposition of the present method to provide accurate analytical results. PMID:19616216

  13. Comparative evaluation of human pulp tissue dissolution by different concentrations of chlorine dioxide, calcium hypochlorite and sodium hypochlorite: An in vitro study

    PubMed Central

    Taneja, Sonali; Mishra, Neha; Malik, Shubhra

    2014-01-01

    Introduction: Irrigation plays an indispensable role in removal of tissue remnants and debris from the complicated root canal system. This study compared the human pulp tissue dissolution by different concentrations of chlorine dioxide, calcium hypochlorite and sodium hypochlorite. Materials and Methods: Pulp tissue was standardized to a weight of 9 mg for each sample. In all,60 samples obtained were divided into 6 groups according to the irrigating solution used- 2.5% sodium hypochlorite (NaOCl), 5.25% NaOCl, 5% calcium hypochlorite (Ca(OCl)2), 10% Ca(OCl)2, 5%chlorine dioxide (ClO2) and 13% ClO2. Pulp tissue was placed in each test tube carrying irrigants of measured volume (5ml) according to their specified subgroup time interval: 30 minutes (Subgroup A) and 60 minutes (Subgroup B). The solution from each sample test tube was filtered and was left for drying overnight. The residual weight was calculated by filtration method. Results: Mean tissue dissolution increases with increase in time period. Results showed 5.25% NaOCl to be most effective at both time intervals followed by 2.5% NaOCl at 60 minutes, 10%Ca(OCl)2 and 13% ClO2 at 60 minutes. Least amount of tissue dissolving ability was demonstrated by 5% Ca(OCl)2 and 5% ClO2 at 30 minutes. Distilled water showed no pulp tissue dissolution. Conclusion: Withinthe limitations of the study, NaOCl most efficiently dissolved the pulp tissue at both concentrations and at both time intervals. Mean tissue dissolution by Ca(OCl)2 and ClO2 gradually increased with time and with their increase in concentration. PMID:25506141

  14. A realistic molecular model of cement hydrates

    E-print Network

    Ulm, Franz-Josef

    Despite decades of studies of calcium-silicate-hydrate (C-S-H), the structurally complex binder phase of concrete, the interplay between chemical composition and density remains essentially unexplored. Together these ...

  15. Terahertz spectroscopy of concrete for evaluating the critical hydration level

    NASA Astrophysics Data System (ADS)

    Dash, Jyotirmayee; Ray, Shaumik; Nallappan, Kathirvel; Sasmal, Saptarshi; Pesala, Bala

    2014-03-01

    Concrete, a mixture of cement, coarse aggregate, sand and filler material (if any), is widely used in the construction industry. Cement, mainly composed of Tricalcium Silicate (C3S) and Dicalcium Silicate (C2S) reacts readily with water, a process known as hydration. The hydration process forms a solid material known as hardened cement paste which is mainly composed of Calcium Silicate Hydrate (C-S-H), Calcium Hydroxide and Calcium Carbonate. To quantify the critical hydration level, an accurate and fast technique is highly desired. However, in conventional XRD technique, the peaks of the constituents of anhydrated and hydrated cement cannot be resolved properly, where as Mid-infrared (MIR) spectroscopy has low penetration depth and hence cannot be used to determine the hydration level of thicker concrete samples easily. Further, MIR spectroscopy cannot be used to effectively track the formation of Calcium Hydroxide, a key by-product during the hydration process. This paper describes a promising approach to quantify the hydration dynamics of cement using Terahertz (THz) spectroscopy. This technique has been employed to track the time dependent reaction mechanism of the key constituents of cement that react with water and form the products in the hydrated cement, viz., C-S-H, Calcium Hydroxide and Calcium Carbonate. This study helps in providing an improved understanding on the hydration kinetics of cement and also to optimise the physio-mechanical characteristics of concrete.

  16. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food...

  17. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food...

  18. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food...

  19. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food...

  20. 21 CFR 184.1721 - Sodium acetate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the specifications of the Food...

  1. Lab Procedure Sodium Borate Crystals

    E-print Network

    Pike, Robert D.

    Lab Procedure Sodium Borate Crystals Materials: Plastic cup, marked for 50 mL Styrofoam cup 50 m a styrofoam cup, Sodium Borate solution. 2. Place 2 teaspoons of sodium borate in the Styrofoam cup. 3. Place hydrate Plastic cup, marked for 50 mL Styrofoam cup 50 mL of deionized water Plastic spoon String

  2. Separation of sodium-22 from irradiated targets

    DOEpatents

    Taylor, Wayne A. (Los Alamos, NM); Jamriska, David (Los Alamos, NM)

    1996-01-01

    A process for selective separation of sodium-22 from an irradiated target including dissolving an irradiated target to form a first solution, contacting the first solution with hydrated antimony pentoxide to selectively separate sodium-22 from the first solution, separating the hydrated antimony pentoxide including the separated sodium-22 from the first solution, dissolving the hydrated antimony pentoxide including the separated sodium-22 in a mineral acid to form a second solution, and, separating the antimony from the sodium-22 in the second solution.

  3. Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxide—calcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Christensen, Axel Nørlund; Jensen, Torben R.; Hanson, Jonathan C.

    2004-06-01

    In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 4·2H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 12·26H 2O, monosulfate, Ca 4Al 2O 6(SO 4)·14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 7·19H 2O. Ettringite is formed if sufficient CaSO 4·2H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 4·2H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170°C using in situ synchrotron X-ray powder diffraction. This technique allows the study of very fast chemical reactions that are observed here under hydrothermal conditions. A new experimental approach was developed to perform in situ mixing of the reactants during X-ray data collection.

  4. Regulation of the sodium/potassium/chloride cotransporter by calcium and cyclic AMP in cultured vascular smooth muscle cells

    SciTech Connect

    Higgins, B.L.; Smith, L.; Smith, J.B.

    1987-05-01

    The activity of the Na/K/Cl cotransporter in smooth muscle cells cultured from rat aorta was assayed by measuring the initial rate of furosemide-inhibitable /sup 86/Rb influx or efflux. Five uM furosemide or 0.2 uM bumetanide inhibited influx by 50%. Furosemide-inhibitable /sup 86/Rb influx depended on the presence of all 3 ions in the external medium. The dependence on Na and K was hyperbolic with apparent Km values of 45 and 5 mM, respectively. The dependence on Cl was sigmoidal. Assuming a stoichiometry of 1:1:2 for Na:K:Cl, a Km for Cl of 60 mM was obtained from a Hofstee plot of the data. Rapidly growing cells had 3 fold higher cotransport activity than quiescent cells. Angiotensin II (ANG) stimulated furosemide-inhibitable /sup 86/Rb efflux by 2 fold. An ANG receptor antagonist prevented ANG from increasing cotransport activity. Two calcium ionophores, A23187 and ionomycin, increased cotransport activity by 2 fold. Phorbol myristate acetate had no effect on cotransport activity. Isoproterenol, dibutyryl cyclic AMP, cholera toxin, or methylisobutylxanthine inhibited furosemide-sensitive /sup 86/Rb influx by 35 to 50%. From these findings they conclude that increasing cytoplasmic free calcium stimulates cotransport activity, whereas increasing cellular cyclic AMP inhibits the cotransporter.

  5. Slurry Consistency and In-situ Synchrotron X-ray Diffraction during the Early Hydration of Portland Cements with Calcium Chloride

    SciTech Connect

    Jupe, A.C.; Wilkinson, A.P.; Luke, K.; Funkhouser, G.P. (Halliburton); (GIT)

    2008-07-08

    Class A and H oil well cements are compared at 25 and 50 C with 0%, 1%, 2%, and 4% CaCl{sub 2}. Up to 4% CaCl{sub 2} accelerated Class A thickening, but 4% led to slower thickening than 2% for Class H. C{sub 3}S hydration in the two cements responded differently to CaCl{sub 2}. CaCl{sub 2} always accelerated aluminate hydration. For Class A, CaCl{sub 2} accelerated early Ca(OH){sub 2} precipitation, but sometimes reduced the amount at longer times. This may be coupled to C-S-H gel composition changes. For Class H, Ca(OH){sub 2} precipitation changes nonlinearly with CaCl{sub 2} concentration. Ettringite to monosulfate conversion and Friedel's salt formation were sometimes seen.

  6. Gas hydrates

    SciTech Connect

    Not Available

    1985-04-01

    There is a definite need for the US government to provide leadership for research in gas hydrates and to coordinate its activities with academia, industry, private groups, federal agencies, and their foreign counterparts. In response to this need, the DOE Morgantown Energy Technology Center implemented a gas hydrates R and D program. Understanding the resource will be achieved through: assessment of current technology; characterization of gas hydrate geology and reservoir engineering; and development of diagnostic tools and methods. Research to date has focused on geology. As work progressed, areas where gas hydrates are likely to occur were identified, and specific high potential areas were targeted for future detailed investigation. Initial research activities involved the development of the Geologic Analysis System (GAS); which will provide, through approximately 30 software packages, the capability to manipulate and correlate several types of geologic and petroleum data into maps, graphics, and reports. Preliminary mapping of hydrate prospects for the Alaskan North Slope is underway. Geological research includes physical system characterization which focuses on creating synthetic methane hydrates and developing synthetic hydrate cores using tetrahydrofuran, consolidated rock cores, frost base mixtures, water/ice base mixtures, and water base mixtures. Laboratory work produced measurements of the sonic velocity and electrical resistivity of these synthetic hydrates. During 1983, a sample from a natural hydrate core recovered from the Pacific coast of Guatemala was tested for these properties by METC. More recently, a natural hydrate sample from the Gulf of Mexico was also acquired and testing of this sample is currently underway. In addition to the development of GAS, modeling and systems analysis work focused on the development of conceptual gas hydrate production models. 16 figs., 6 tabs.

  7. Combustion synthesis of calcium aluminates

    Microsoft Academic Search

    D. A. Fumo; M. R. Morelli; A. M. Segadães

    1996-01-01

    Commercial calcium aluminate cements for refractory use are known to contain various phases, the hydration behavior of which is interdependent and not fully understood. Hydration studies normally require that pure oxides be synthesized. Solid-state synthesis of single aluminates requires high temperatures and full conversion is not guaranteed. Moreover, it is difficult to obtain a compositionally homogeneous product with this method.

  8. Effect of dietary moisture and sodium content on urine composition and calcium oxalate relative supersaturation in healthy miniature schnauzers and labrador retrievers.

    PubMed

    Stevenson, A E; Hynds, W K; Markwell, P J

    2003-04-01

    The aim of this series of studies was to evaluate two possible feeding strategies as methods for reducing the risk of calcium oxalate (CaOx) formation in two breeds of healthy dog. The studies compared the effect of dietary moisture (Study 1) and dietary sodium (Na), (Study 2) on urine composition of labrador retrievers (LR) and miniature schnauzers (MS). A nutritionally complete dry dog food was fed to 16 dogs (eight LR, eight MS; Study 1) and 15 dogs (seven LR, eight MS; Study 2) for 24 days (Study 1), or 36 days (Study 2). The dogs were fed the diet alone (7% moisture, 0.06 g Na/100 kcal), or supplemented with deionised water to 73% moisture (Study 1), or dietary Na, to deliver 0.20 or 0.30 g Na per 100 kcal (Study 2). Urine pH, volume, specific gravity, and concentrations of 12 analytes were measured for each dog. Urinary relative supersaturations (RSS) with CaOx were calculated from these values. The effects of supplemental Na or water were established using t tests (Study 1) or analysis of variance, and multiple range tests (least significant difference) (Study 2); P<0.05 was considered significant. Increasing dietary moisture significantly increased total moisture intake (P=0.001), and reduced urine specific gravity (P=0.003), urinary oxalate concentration (P=0.04), and CaOx relative supersaturation (P=0.04) in the MS. Urinary parameters remained unchanged in the LR, indicating that feeding a high moisture diet may reduce the risk of CaOx formation in high-risk breeds. Increasing dietary Na led to production of urine with a significantly lower CaOx RSS in both breeds, indicating that sodium supplementation to dry diet formats may reduce the risk of CaOx formation. These feeding strategies should be considered when evaluating methods for preventing CaOx formation within high-risk groups. PMID:12589739

  9. Sodium Phosphate Rectal

    MedlinePLUS

    ... widening of the intestine), dehydration, low levels of calcium, sodium, magnesium, or potassium in your blood, or kidney disease.tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding.

  10. Chemically mimicked hypoxia modulates gene expression and protein levels of the sodium calcium exchanger in HEK 293 cell line via HIF-1?.

    PubMed

    Hudecova, Sona; Lencesova, Lubomira; Csaderova, Lucia; Sirova, Marta; Cholujova, Dana; Cagala, Martin; Kopacek, Juraj; Dobrota, Dusan; Pastorekova, Silvia; Krizanova, Olga

    2011-06-01

    Up to now a little is known about the effect of hypoxia on the sodium calcium exchanger type 1 (NCX1) expression and function. Therefore, we studied how dimethyloxallyl glycine (DMOG), an activator and stabilizer of the hypoxia-inducible factor (HIF)-1?, could affect expression of the NCX1 in HEK 293 cell line. We also tried to determine whether this activation can result in the induction of apoptosis in HEK 293 cells. We have found that DMOG treatment for 3 hours significantly increased gene expression and also protein levels of the NCX1. This increase was accompanied by a decrease in intracellular pH. Wash-out of DMOG did not result in reduction of the NCX1 mRNA and protein to original - control levels, although pH returned to physiological values. Using luciferase reporter assay we observed increase in the NCX1 promoter activity after DMOG treatment and using wild-type mouse embryonic fibroblast (MEF)-HIF-1(+/+) and HIF-1-deficient MEF-HIF-1(-/-) cells we have clearly shown that in the promoter region, HIF-1? is involved in DMOG induced upregulation of the NCX1. Moreover, we also showed that an increase in the NCX1 mRNA due to the apoptosis induction is not regulated by HIF-1?. PMID:21613675

  11. 40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...acetate, calcium magnesium potassium sodium salt. 721.2076 Section 721.2076 Protection...acetate, calcium magnesium potassium sodium salt. (a) Chemical substance and significant...acetate, calcium magnesium potassium sodium salt (PMN P-00-7; CAS...

  12. 40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...acetate, calcium magnesium potassium sodium salt. 721.2076 Section 721.2076 Protection...acetate, calcium magnesium potassium sodium salt. (a) Chemical substance and significant...acetate, calcium magnesium potassium sodium salt (PMN P-00-7; CAS...

  13. Isoproterenol accelerates apoptosis through the over-expression of the sodium/calcium exchanger in HeLa cells.

    PubMed

    Hudecova, Sona; Lencesova, Lubomira; Csaderova, Lucia; Sedlak, Jan; Bohacova, Viera; Laukova, Marcela; Krizanova, Olga

    2013-09-01

    Apoptosis induction causes over-expression of the Na+/Ca2+ exchanger of type 1 (NCX1) in the HeLa cell line. During induction of apoptosis and in the presence of isoproterenol hydrochloride (I; ?-adrenergic agonist), increase in the NCX1 is even more pronounced. Anti-apoptotic Bcl-2 mRNA and protein is markedly reduced during apoptosis and in the presence of I, which causes a rapid increase in the Bax/Bcl-2 ratio. During apoptosis induction by apoptosis inducing kit (A), both with and without I, the active form of caspase-3, which is the executive enzyme in apoptosis, becomes visible on Western blots. Silencing NCX1 resulted in the reversal of the Bax/Bcl-2 ratio, it prevented a decrease in mitochondrial membrane potential compared to the AI group and it decreased the level of AI-induced apoptosis in HeLa cells. Based on the experiments with single apoptotic inducers camptothecin, cycloheximide and dexamethasone, it might be proposed that potentiated apoptotic effect in I-treated cells is due to the inhibition of nuclear topoisomerase. As illustrated in immunofluorescence and Western blot analysis, calnexin increased significantly during induction of the apoptosis in the presence of I. In addition, further decrease in sarco/endoplasmic ATPase 2 (SERCA2), decrease in reticular calcium and mitochondrial membrane potential was observed, which suggests development of the endoplasmic reticulum (ER) stress. Based on these results, we propose that I further enhanced NCX1 expression in apoptotic cells through the development of ER stress. PMID:23817639

  14. Deep formation waters of Western Europe, Russia and North America characterised by sodium, calcium, magnesium and chloride concentrations

    NASA Astrophysics Data System (ADS)

    Bozau, Elke; Hemme, Christina; Sattler, Carl-Diedrich; van Berk, Wolfgang

    2015-04-01

    Deep formation water can be classified according to depth, temperature, and salinity (e.g., Graf et al. 1966, Kharaka & Hanor 2007). Most of the deep formation waters contain dissolved solids in excess of sea water. The hydrogeochemical development of formation water has been discussed for a long time. It is widely accepted that deep aquifers are influenced by the meteoric cycle and geochemical processes within the crust (e.g., Hebig et al. 2012). Similar hydrogeochemical signatures are found in deep formation waters of all continents and can be explained by general geochemical processes within the deep reservoirs (e.g., Land 1995). Therefore, data of deep formation waters from Western Europe, Russia, and North America are collected and classified by the major water components. The data are used to identify important hydrogeochemical processes (e.g., halite dissolution and albitisation) leading to different compositions of formation water. Two significant water types are identified: Na-Cl water and Na-Ca-Cl water. Based on the collected hydrogeochemical data, development trends are stated for the formation waters, and albitisation is favoured as the main process for calcium enrichment. Furthermore, differences of formation water according to stratigraphical units are shown for deep reservoirs of the North German Basin and the North Sea. References: Graf, D.L., 1982. Chemical osmosis, reverse chemical osmosis, and the origin of subsurface brines. Geochimica Cosmochimica Acta 46, 1431-1448. Hebig, K.H., Ito, N., Scheytt, T., Marui, A., 2012. Review: Deep groundwater research with focus on Germany. Hydrogeology Journal 20, 227-243. Kharaka, Y.K., Hanor, J.S., 2007. Deep fluids in continents: I. Sedimentary Basins. Treatise on Geochemistry 5, 1-48. Land, L.S., 1995. The role of saline formation water in the crustal cycling. Aquatic Geochemistry 1, 137-145. Acknowledgements: The presented data are results of the collaborative research program "gebo" (Geothermal energy and high performance drilling), financed by the Ministry of Science and Culture of the Federal State of Lower Saxony and industry partner Baker Hughes Celle.

  15. Final Report on the Safety Assessment of Aluminum Silicate, Calcium Silicate, Magnesium Aluminum

    E-print Network

    Ahmad, Sajjad

    Final Report on the Safety Assessment of Aluminum Silicate, Calcium Silicate, Magnesium Aluminum Sodium Silicate, Montmorillonite, Pyrophyllite, and Zeolite1 This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium

  16. Integration time in a subset of spinal lamina I neurons is lengthened by sodium and calcium currents acting synergistically to prolong subthreshold depolarization.

    PubMed

    Prescott, Steven A; De Koninck, Yves

    2005-05-11

    Lamina I of the spinal dorsal horn plays an important role in processing and relaying nociceptive information to the brain. It comprises physiologically distinct cell types that process information in fundamentally different ways: tonic neurons fire repetitively during stimulation and display prolonged EPSPs, suggesting operation as integrators, whereas single-spike neurons act like coincidence detectors. Using whole-cell recordings from a rat spinal slice preparation, we set out to determine the basis for prolonged EPSPs in tonic cells and the implications for signal processing. Kinetics of synaptic currents could not explain differences in EPSP kinetics. Instead, tonic neurons were found to express a persistent sodium current, I(Na,P), that amplified and prolonged depolarization in response to brief stimulation. Tonic neurons also expressed a persistent calcium current, I(Ca,P), that contributed to prolongation but not to amplification. Simulations using NEURON software demonstrated that I(Na,P) was necessary and sufficient to explain amplification, whereas I(Na,P) and I(Ca,P) acted synergistically to prolong depolarization: initial activation of the slower current (I(Ca,P)) depended on the faster current (I(Na,P)) but maintained activation of the faster current likewise depended on the slower current. Additional investigation revealed that I(Na,P) and I(Ca,P) could dramatically increase integration time (>30x) and thereby encourage temporal summation but at the expense of spike time precision. Thus, by prolonging subthreshold depolarization, intrinsic inward currents allow tonic neurons in spinal lamina I to specialize as integrators that are optimally suited to encode stimulus intensity. PMID:15888650

  17. Effects of a Fusarium toxin-contaminated maize treated with sodium metabisulphite, methylamine and calcium hydroxide in diets for female piglets.

    PubMed

    Rempe, Inga; Brezina, Ulrike; Kersten, Susanne; Dänicke, Sven

    2013-08-01

    Deoxynivalenol (DON) and zearalenone (ZEN) contaminated maize was hydrothermally treated in the presence of sodium metabisulphite (SBS), methylamine and calcium hydroxide (Ca(OH)2) and included into diets for female piglets to evaluate effects on performance, organ weights, development of hyperestrogenism, serum biochemical parameters, stimulation of peripheral blood mononuclear cells and toxin residues in serum. For this purpose, both uncontaminated maize (CON) and Fusarium toxin-contaminated maize (FUS) were included into diets either untreated (-) or treated (+) according to a 2 by 2-factorial design. One-hundred female weaned piglets were assigned to one of the four treatment groups (n = 25) CON-, CON+, FUS- and FUS+ with DON/ZEN concentrations of 0.43/0.03, 0.04/0.0, 3.67/0.32 and 0.36/0.08 mg per kg diet, respectively. After a feeding period of 27 days, 20 piglets (n = 5) were slaughtered. Performance parameters such as feed intake, live weight gain and feed-to-gain ratio remained unaffected by the treatments. Uterus weights were significantly reduced in group FUS+ compared to FUS- (p = 0.028), while visceral organ weights were not influenced. Vulva width in relation to body weight was highest in group FUS- at the end of the trial, while hydrothermal treatment significantly reduced the parameter (p < 0.01). The highest toxin and toxin metabolite concentrations in serum were detected in group FUS-, whereas ingestion of diet FUS+ reduced the concentrations to the level of the control groups. Serum biochemical and haematological parameters were mainly within the given reference ranges and showed no treatment-related alterations. Stimulation of peripheral blood mononuclear cells was not affected. An effective detoxification of maize by hydrothermal treatment in the presence of SBS, methylamine and Ca(OH)2 could be demonstrated by means of serum toxin analyses. No undesired side effects of the treated-feed stuff or the chemicals themselves on the health of piglets were detected. PMID:23859352

  18. A Solution NMR Investigation into the Early Events of Amelogenin Nanosphere Self-Assembly Initiated with Sodium Chloride or Calcium Chloride†

    PubMed Central

    Buchko, Garry W.; Tarasevich, Barbara J.; Bekhazi, Jacky; Snead, Malcolm L.; Shaw, Wendy J.

    2009-01-01

    Using solution-state NMR spectroscopy, new insights into the early events governing amelogenin supramolecular self-assembly have been identified using sodium chloride and calcium chloride to trigger the association. Two-dimensional 1H–15N HSQC spectra were recorded for 15N- and 13C-labeled murine amelogenin as a function of increasing NaCl and CaCl2 concentration beginning with solution conditions of 2% acetic acid at pH 3.0, where amelogenin was monomeric. Residue specific changes in molecular dynamics, manifested by the reduction in intensity and disappearance of 1H–15N HSQC cross-peaks, were observed with the addition of either salt to the protein. With increasing NaCl concentrations, residues between T21 and R31 near the N-terminus were affected first, suggesting that these residues may initiate amelogenin dimerization, the first step in nanosphere assembly. At higher NaCl concentrations, more residues near the N-terminus (Y12–I51) were affected, and with further additions of NaCl, residues near the C-terminus (L141–T171) began to show a similar change in molecular dynamics. With increasing CaCl2 concentrations, a similar stepwise change in molecular dynamics involving essentially the same set of amelogenin residues was observed. As the concentration of either salt was increased, a concomitant increase in the estimated overall rotational correlation time (?c) was observed, consistent with assembly. Self-assembly into a dimer or trimer was established with dynamic light scattering studies under similar conditions that showed an increase in diameter of the smallest species from 4.1 nm in the absence of salt to ~10 nm in the presence of salt. These results suggest a possible stepwise interaction mechanism, starting with the N-terminus and followed by the C-terminus, leading to amelogenin nanosphere assembly. PMID:19086270

  19. Thiosulfate Reduces Calcium Phosphate Nephrolithiasis

    PubMed Central

    Asplin, John R.; Donahue, Susan E.; Lindeman, Christina; Michalenka, Anne; Strutz, Kelly Laplante; Bushinsky, David A.

    2009-01-01

    An uncontrolled trial reported that sodium thiosulfate reduces formation of calcium kidney stones in humans, but this has not been established in a controlled human study or animal model. Using the genetic hypercalciuric rat, an animal model of calcium phosphate stone formation, we studied the effect of sodium thiosulfate on urine chemistries and stone formation. We fed genetic hypercalciuric rats normal food with or without sodium thiosulfate for 18 wk and measured urine chemistries, supersaturation, and the upper limit of metastability of urine. Eleven of 12 untreated rats formed stones compared with only three of 12 thiosulfate-treated rats (P < 0.002). Urine calcium and phosphorus were higher and urine citrate and volume were lower in the thiosulfate-treated rats, changes that would increase calcium phosphate supersaturation. Thiosulfate treatment lowered urine pH, which would lower calcium phosphate supersaturation. Overall, there were no statistically significant differences in calcium phosphate supersaturation or upper limit of metastability between thiosulfate-treated and control rats. In vitro, thiosulfate only minimally affected ionized calcium, suggesting a mechanism of action other than calcium chelation. In summary, sodium thiosulfate reduces calcium phosphate stone formation in the genetic hypercalciuric rat. Controlled trials testing the efficacy and safety of sodium thiosulfate for recurrent kidney stones in humans are needed. PMID:19369406

  20. Effect of Azadirachta indica (neem), sodium thiosulphate and calcium chloride on changes in nitrogen transformations and inhibition of nitrification in soil incubated under laboratory conditions.

    PubMed

    Abbasi, M Kaleem; Hina, Munazza; Tahir, Majid Mahmood

    2011-03-01

    A laboratory experiment was conducted to examine the effects of nitrification inhibitors (NIs) neem seed-cake (Azadirachta indica) (NSC), sodium thiosulphate (Na?S?O?) and calcium chloride (CaCl?) on changes in NH?(+)?N, inhibition of nitrification and recovery of applied nitrogen (N) in soil. Surface soil samples of 0-15 cm were collected from an arable field, amended with urea N (UN) at the rate 200 mg N kg?¹, UN+NSC, UN+Na?S?O? and UN+CaCl? and incubated at 22°C periodically over 50 d. Soil without any amendment was used as check (control). Results indicated that more than 58% of N applied as NH?? disappeared over a period of 50 d from the soil mineral-N pool. Some of this N (21%) was accumulated as NO??-N while the remaining N was unaccounted for. Addition of nitrification inhibitors NSC, Na?S?O?, and CaCl? resulted in a decrease in the extent of NH?(+) disappearance by 35%, 44% and 30%, respectively. In the treatment receiving UN alone, 56 mg NO??-N kg?¹ was accumulated over 50 d (maximum 93 mg kg?¹) indicated an active nitrification. Application of nitrification inhibitors NSC, Na?S?O?, and CaCl? with UN inhibited nitrification by 54%, 64%, and 59%, respectively. Apparent N recovery (ANR) in the treatment receiving UN alone was 63% that substantially increased to 83%, 89% and 76% in the treatments receiving UN+NSC, UN+Na?S?O?, and UN+CaCl?, respectively indicating 32%, 41% and 20% increase in N recovery. Among three NIs tested, Na?S?O? proved superior in inhibiting nitrification and increasing ANR. The study demonstrated that application of NSC, Na?S?O?, and CaCl? which are cheap and easily available NIs inhibited nitrification and improved N recovery efficiency of applied N in an arable soil very effectively. It is suggested that these inhibitors should be tested under field conditions for increasing NUE and improving crop productivity. PMID:21146192

  1. The nature of the hydration products in hardened cement pastes

    Microsoft Academic Search

    I. G Richardson

    2000-01-01

    An understanding of the performance of portland cement-based materials requires knowledge at the microstructural level. Developments in the instrumentation of several techniques have led to improved understanding of the composition, morphology, and spatial distribution of the various products of cement hydration. In particular, our understanding of the nature of the nearly amorphous calcium silicate hydrate (C–S–H) phases – which are

  2. Standard enthalpies of formation of francium hydroxide hydrates

    Microsoft Academic Search

    Burylev

    1995-01-01

    Available experimental data on standard enthalpies of formation of alkali metal hydroxide hydrates have been summarized. Using equations derived, the authors have calculated previously unknown enthalpies of formation of some lithium, sodium, potassium, rubidium, and cesium hydroxide hydrates. Taking into account the contribution of water to the enthalpies of formation of monohydrates, the authors have estimated the enthalpies of formation

  3. Nonenzymatic Transformation of Amorphous CaCO3 into Calcium Phosphate Mineral after Exposure to Sodium Phosphate in Vitro: Implications for in Vivo Hydroxyapatite Bone Formation.

    PubMed

    Müller, Werner E G; Neufurth, Meik; Huang, Jian; Wang, Kui; Feng, Qingling; Schröder, Heinz C; Diehl-Seifert, Bärbel; Muñoz-Espí, Rafael; Wang, Xiaohong

    2015-06-15

    Studies indicate that mammalian bone formation is initiated at calcium carbonate bioseeds, a process that is driven enzymatically by carbonic anhydrase (CA). We show that amorphous calcium carbonate (ACC) and bicarbonate (HCO3 (-) ) cause induction of expression of the CA in human osteogenic SaOS-2 cells. The mineral deposits formed on the surface of the cells are rich in C, Ca and P. FTIR analysis revealed that ACC, vaterite, and aragonite, after exposure to phosphate, undergo transformation into calcium phosphate. This exchange was not seen for calcite. The changes to ACC, vaterite, and aragonite depended on the concentration of phosphate. The rate of incorporation of phosphate into ACC, vaterite, and aragonite, is significantly accelerated in the presence of a peptide rich in aspartic acid and glutamic acid. We propose that the initial CaCO3 bioseed formation is driven by CA, and that the subsequent conversion to calcium phosphate/calcium hydroxyapatite (exchange of carbonate by phosphate) is a non-enzymatic exchange process. PMID:25871446

  4. Identifying inhibitors of hydrate formation rate with viscometric experiments

    SciTech Connect

    Kalbus, J.S.; Christiansen, R.L.; Sloan, D. Jr.

    1995-12-31

    Inhibiting the rate of hydrate formation with low concentration additives is an economically and environmentally attractive alternative to prevention of hydrates with large doses of methanol. Here, a method for screening possible rate inhibitors is described. In the method, a viscometer is used to follow the development of hydrate formation for water-THF solutions and for water-gas solutions at conditions favoring hydrate formation. The method was applied to about 30 different chemicals, plus binary combinations of many of these chemicals. The best chemical additives included BASF F-127, Mirawet ASC, Surfynol-465, sodium dodecyl sulfate(SDS), Mirataine CBS with polyvinylpyrrolidone(PVP), and SDS with PVP.

  5. Clinical experience with sodium cellulose phosphate

    Microsoft Academic Search

    Charles Y. C. Pak; Michael J. Nicar; Faye Britton

    1983-01-01

    There is currently no treatment program which is capable of correcting the basic abnormality of absorptive hypercalciuria, although several drugs are available which have been shown to restore normal calcium excretion. Sodium cellulose phosphate best meets the criteria for optimum therapy. When given orally, this non-absorbable ion exchange resin binds calcium and inhibits calcium absorption. However, this inhibition is caused

  6. Calcium supplements

    MedlinePLUS

    ... The two main forms of calcium pills are: Calcium carbonate: Over-the-counter antacid products, such as Tums and Rolaids contain calcium carbonate. These sources of calcium carbonate do not cost ...

  7. Pilot investigation of the hydrating effects of topical acne medications.

    PubMed

    Zhen, Yaxian; Stoudemayer, Marianne; Vamvakias, George; Kligman, Albert M

    2007-08-01

    Topical therapies are effective in managing acne vulgaris but are associated with local adverse effects such as irritation and dryness. This 4-week pilot study compared skin hydration in 36 healthy adult women randomized to treatment with 1 of 4 topical therapies: 2 different (jar and tube) clindamycin 1%/benzoyl peroxide 5% gels, sodium sulfacetamide 10% lotion, or over-the-counter (OTC) moisturizing cream. Subjects treated with OTC moisturizer or sodium sulfacetamide exhibited decreased water loss, increased water retention, similar or improved levels of skin hydration, and decreased desorption rates. In contrast, subjects treated with jar or tube clindamycin/benzoyl peroxide had increased water loss, decreased water retention, decreased hydration, and increased desorption rates. Skin dryness decreased slightly in the moisturizer group. No serious adverse events occurred. Overall, the OTC moisturizer had the best skin hydration profile. Sodium sulfacetamide demonstrated some moisturizing characteristics, and no clinically relevant differences were noted between jar and tube clindamycin/benzoyl peroxide gels. PMID:17763612

  8. Clathrate hydrates in nature.

    PubMed

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves. PMID:21141039

  9. Neurotransmitters Calcium ions

    E-print Network

    Cai, Long

    Actin Nerve terminal Active zone Neurotransmitters Calcium ions Sodium ions Ultrafast endocytosis.These`bouton-type'ter- minalscontainapproximately200synapticves- icles (30­40 nanometres across), each packed with about 2,000 neurotransmitter). It is thought that one to three of those docked vesicles are primed to release neurotransmitters by a process

  10. The healthy newborn hydration model: a new model for understanding newborn hydration immediately after birth.

    PubMed

    Mulder, Pamela J; Gardner, Sue E

    2015-01-01

    The normal small volume of breast milk produced in the first 2 days following birth may raise concerns about adequate hydration in breast-fed newborns. These concerns are further magnified when breast-fed infants lose ?7% of their birth weight within 2 days postnatally. Weight loss following birth is presumably mostly water loss that could result in hypohydration and subsequent hypernatremic dehydration. However, excess fluid loss immediately following birth is a normal and necessary process. Furthermore, newborns exposed to excess fluid intake during labor may need to lose ?7% of birth weight in the first 2 days following birth in order to achieve euhydration. Normal newborn fluid loss following birth confounds the use of weight loss as the sole measure of newborn hydration. We thus propose the healthy newborn hydration model that highlights the normalcy of newborn weight loss immediately following birth and the healthy newborn's compensatory mechanisms for preserving adequate hydration. We also recommend the use of serum sodium to measure intravascular osmolarity in addition to monitoring weight loss to obtain a more comprehensive newborn hydration assessment. Research is necessary in healthy newborns to identify relationships among fluids received in utero, newborn weight loss, and hydration, as evaluated with laboratory measures, in the first 2 days following birth. This information will guide clinicians in correctly identifying newborns with inadequate hydration who are in need of supplementary fluids versus newborns with adequate hydration for whom exclusive breast-feeding can be supported and encouraged. PMID:25504955

  11. Does a glycine sodium nitrite crystal exist?

    E-print Network

    Dhavskar, Kiran T

    2015-01-01

    The glycine sodium nitrite crystal reported by Khandpekar and Pati in the paper entitled, Synthesis and characterisation of glycine sodium nitrite crystals having non linear optical behaviour, Opt Commun 285, 2012 288-293 is actually gamma-glycine. In addition, we show that glycine barium ammonium nitrate, glycine sodium zinc sulfate, glycine barium calcium nitrate, glycine acetamide and glycine dimer are dubious crystals.

  12. Conservation of body calcium by increased dietary intake of potassium: A potential measure to reduce the osteoporosis process during prolonged exposure to microgravity

    NASA Technical Reports Server (NTRS)

    Nechay, Bohdan R.

    1989-01-01

    During the 1988 NASA Summer Faculty Fellowship Program, it was proposed that the loss of skeletal calcium upon prolonged exposure to microgravity could be explained, in part, by a renal maladjustment characterized by an increased urinary excretion of calcium. It was theorized that because the conservation of body fluids and electrolytes depends upon the energy of adenosine triphosphate and enzymes that control the use of its energy for renal ion transport, an induction of renal sodium and potassium-dependent adenosine triphosphatase (Na + K ATPase) by oral loading with potassium would increase the reabsorption of sodium directly and that of calcium indirectly, leading to improved hydration and to reduced calcium loss. Preliminary studies showed the following. Rats drinking water containing 0.2 M potassium chloride for six to 13 days excreted in urine 22 muEq of calcium and 135 muEq of sodium per 100 grams of body weight per day. The corresponding values for control rats drinking tap water were 43 muEq and 269 muEq respectively. Renal Na + K ATPase activity in potassium loaded rats was higher than in controls. Thus, oral potassium loading resulted in increased Na + K ATPase activity and diminished urinary excretion of calcium and of sodium as predicted by the hypothesis. An extension of these studies to humans has the potential of resulting in development of harmless, non-invasive, drug-free, convenient measures to reduce bone loss and other electrolyte and fluid problems in space travelers exposed to prolonged periods of microgravity.

  13. Quadrupole splitting in sodium ferrocyanide

    Microsoft Academic Search

    M. J. Evans; P. J. Black

    1970-01-01

    Mossbauer spectra from a single crystal of hydrated sodium ferrocyanide indicate a shift in line position with crystal orientation which is consistent with a quadrupole splitting of 0.56 gamma o. Voigt profile analysis of spectra from powders indicates a smaller broadening of the Lorentz component, 0.27 Gamma o; the inconsistency is explained by preferred orientation in the absorber samples.

  14. Simultaneous determination of free calcium, magnesium, sodium and potassium ion concentrations in simulated milk ultrafiltrate and reconstituted skim milk using the Donnan Membrane Technique

    Microsoft Academic Search

    R. Gao; E. J. M. Temminghoff; H. P. van Leeuwen; H. J. F. van Valenberg; M. D. Eisner

    2009-01-01

    This study focused on determination of free Ca2+, Mg2+, Na+ and K+ concentrations in a series of CaCl2 solutions, simulated milk ultrafiltrate and reconstituted skim milk using a recently developed Donnan Membrane Technique (DMT). A calcium ion selective electrode was used to compare the DMT results. The study showed that the free Ca2+ concentrations measured by the DMT agreed well

  15. Reactivity of iron carbonyl complexes in a hydrated sodium-Y zeolite matrix and catalysis of the resulting hydride anion HFeâ(CO)âââ» for water-gas-shift reaction

    Microsoft Academic Search

    Masakazu Iwamoto; Shinichiro Nakamura; Hideto Kusano; Shuichi Kagawa

    1986-01-01

    Iron carbonyls Fe(CO)â, Feâ(CO)â, and Feâ(CO)ââ have been introduced into a hydrated Na-Y zeolite. Fe(CO)â was only weakly adsorbed on the zeolite. Feâ(CO)â and Feâ(CO)ââ were reactive in the hydrated zeolite cages to yield a hydride anion species HFeâ(CO)âââ» which was characterized by IR absorption bands at 2044, 1987, 1950, and 1645 cm⁻¹, UV-vis spectrum at 540 nm, and gas-phase

  16. Hydrate-phobic surfaces

    E-print Network

    Smith, Jonathan David, S.M. Massachusetts Institute of Technology

    2011-01-01

    Clathrate hydrate formation and subsequent plugging of deep-sea oil and gas pipelines represent a significant bottleneck for ultra deep-sea production. Current methods for hydrate mitigation focus on injecting thermodynamic ...

  17. Calcium Carbonate

    MedlinePLUS

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  18. Heat evolution in hydrating expansive cement systems

    Microsoft Academic Search

    W. Nocu?-Wczelik; A. Stok; Z. Konik

    2010-01-01

    Calorimetry was applied to follow the hydration of special cement mixtures exhibiting expansion or shrinkage compensation.\\u000a The standard, common cements show generally less or more visible shrinkage on setting and hardening but mixed with and expansive\\u000a agent, usually of aluminate and sulfate nature, they can exhibit the increase of volume. The calcium aluminate cement CAC\\u000a 40 was ground together with

  19. Hydration of obsidian

    Microsoft Academic Search

    T. Laursen; W. A. Lanford

    1978-01-01

    The hydration of obsidian is studied by measuring hydrogen concentration profiles of natural samples hydrated at 90°C, using the 15N resonance nuclear reaction method. The results of this study are well reproduced by the interdiffusion model of Doremus. The importance of the non-amorphous phase of obsidian is discussed. It is pointed out that the precision methods of measuring hydration profiles

  20. Modeling and simulation of cement hydration kinetics and microstructure development

    SciTech Connect

    Thomas, Jeffrey J., E-mail: jthomas39@slb.com [Schlumberger-Doll Research, Cambridge, MA 02139 (United States); Biernacki, Joseph J. [Department of Chemical Engineering, Tennessee Tech University, Cookeville, TN (United States); Bullard, Jeffrey W. [Materials and Construction Research Division, National Institute of Standards and Technology, Gaithersburg, MD (United States); Bishnoi, Shashank [Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi (India); Dolado, Jorge S. [Center for Nanomaterials Application in Construction, LABEIN-Tecnalia, Bilbao (Spain); Scherer, George W. [Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ (United States); Luttge, Andreas [Department of Chemistry, Rice University, Houston, TX (United States)

    2011-12-15

    Efforts to model and simulate the highly complex cement hydration process over the past 40 years are reviewed, covering different modeling approaches such as single particle models, mathematical nucleation and growth models, and vector and lattice-based approaches to simulating microstructure development. Particular attention is given to promising developments that have taken place in the past few years. Recent applications of molecular-scale simulation methods to understanding the structure and formation of calcium-silicate-hydrate phases, and to understanding the process of dissolution of cement minerals in water are also discussed, as these topics are highly relevant to the future development of more complete and fundamental hydration models.

  1. [Calcium--essential for everybody].

    PubMed

    Cichosz, Grazyna; Czeczot, Hanna

    2014-06-01

    Calcium regulates majority of metabolic processes within human organism and its optimal intake decreases risk of metabolic illnesses conditioned by diet. Deficiency of calcium results in higher body max index, increase risk of insulin resistance, diabetes type 2 and osteoporosis. Diet delivering full calcium load diminished impendency of hypertension; calcium regulates tension of smooth muscles of blood vessels, limits neurotransmitters activity and also diminish hazardous activity of sodium chloride. Anticancerogenic activity of calcium results from formation insoluble bile acids and fat acids salts, and most of all, from inhibition of intestine mucosa cells hyper proliferation. Due to presence of vitamin D3, CLA, proteins and bioactive peptides emerging from them, milk is more efficient in prophylaxis of diet conditioned illnesses than calcium supplements. Efficiency of milk and dairy products in treatment of obesity, sclerosis and hypertension has been proved by DASH diet. PMID:25095643

  2. Differential scanning calorimetry study of hydrated ground granulated blast-furnace slag

    Microsoft Academic Search

    W. Sha; G. B. Pereira

    2001-01-01

    The present work involves using differential scanning calorimetry (DSC) in an investigation of the thermal behaviour of hydration products in ground granulated blast-furnace slag (ggbs). The two-step loss of water from calcium silicate hydrates and dehydroxylation of calcium hydroxide (Ca(OH)2) contribute, respectively, to the two major peaks in the DSC curves. Peaks due to the formation of ettringite and Fe2O3

  3. Hydrate characterization research overview

    SciTech Connect

    Malone, R.D.

    1993-06-01

    Gas hydrate research has been focused primarily on the development of a basic understanding of hydrate formation and dissociation in the laboratory, as well as in the field. Laboratory research on gas hydrates characterized the physical system, which focused on creating methane hydrates samples, tetrahydrofuran (THF) hydrate samples, consolidated rock samples, frost base mixtures, water/ice-base mixtures, and water-base mixtures. Laboratory work produced measurements of sonic velocity and electrical resistivity of hydrates. As work progressed, areas, such as the Gulf of Mexico and the Guatemala Trench, where gas hydrates are likely to occur were identified, and specific high potential areas were targeted for detailed investigation. The testing of samples and recovered cores from such areas provided information for detection of hydrate formations in the natural environment. Natural gas hydrate samples have been tested for thermal properties, dissociation properties, fracture mechanics, and optical properties. Acoustical properties were investigated both in the laboratory and, as possible, in the field. Sonic velocity and electrical resistivity measurements will continue to be obtained. These activities have been undertaken in hydrate deposits on Alaska`s North Slope, the Gulf of Mexico and the US East coast offshore, as well as other gas hydrate target areas.

  4. CONTROL OF SOX EMISSIONS BY IN-FURNACE SORBENT INJECTION: CARBONATES VS HYDRATES

    EPA Science Inventory

    The paper provides high-temperature isothermal data on SO2 capture by calcium-based sorbents, obtained in a dispersed-phase reactor for limestones, dolomites, hydrated calcitic limes, and hydrated dolomitic limes as a function of Ca/S molar ratio, temperature, and SO2 partial pre...

  5. 2008 Minerals Yearbook U.S. Department of the Interior

    E-print Network

    most often under the name anhydrous boric acid. Colemanite (hydrated calcium borate), kernite (hydrated sodium borate), tincal, and ulexite (hydrated sodium calcium borate) were the minerals of most commercial worldwide: the sodium borates borax and kernite, the calcium borate colemanite, and the sodium-calcium

  6. 2011 Minerals Yearbook U.S. Department of the Interior

    E-print Network

    , and special quality grades as granules or powder. Colemanite (hydrated calcium borate), kernite (hydrated sodium borate), tincal, and ulexite (hydrated sodium calcium borate) were the minerals of most commercial by industry worldwide: the sodium borates tincal and kernite, the calcium borate colemanite, and the sodium-calcium

  7. The Effect of Modified Atmosphere Packaging and Addition of Rosemary Extract, Sodium Acetate and Calcium Lactate Mixture on the Quality of Pre-cooked Hamburger Patties during Refrigerated Storage

    PubMed Central

    Muhlisin; Kang, Sun Moon; Choi, Won Hee; Lee, Keun Taik; Cheong, Sung Hee; Lee, Sung Ki

    2013-01-01

    The effect of modified atmosphere packaging (MAP; 30% CO2+70% N2 or 100% N2) and an additive mixture (500 ppm rosemary extract, 3,000 ppm sodium acetate and 1,500 ppm calcium lactate) on the quality of pre-cooked hamburger patties during storage at 5°C for 14 d was evaluated. The addition of the additive mixture reduced aerobic and anaerobic bacteria counts in both 30% CO2-MAP (30% CO2+70% N2) and 100% N2-MAP (p<0.05). The 30% CO2-MAP was more effective to suppress the microbial growth than 100% N2-MAP, moreover the 30% CO2-MAP combined with additive mixture resulted in the lowest bacterial counts. The hamburger patties with additive mixture showed lower CIE L* and CIE a*, and higher CIE b* than those with no additive mixture. The 30% CO2-MAP tended to decrease the TBARS during storage regardless of the addition of additives. The use of 30% CO2-MAP in combination with additives mixture was effective for maintaining the quality and extending the shelf-life of pre-cooked hamburger patties. PMID:25049716

  8. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding from the experimental component of the research was that hydrates can burn completely, and that they burn most rapidly just after ignition and then burn steadily when some of the water in the dissociated zone is allowed to drain away. Excessive surfactant in the water creates a foam layer around the hydrate that acts as an insulator. The layer prevents sufficient heat flux from reaching the hydrate surface below the foam to release additional methane and the hydrate flame extinguishes. No self-healing or ice-freezing processes were observed in any of the combustion experiments. There is some variability, but a typical hydrate flame is receiving between one and two moles of water vapor from the liquid dissociated zone of the hydrate for each mole of methane it receives from the dissociating solid region. This limits the flame temperature to approximately 1800 K. In the theoretical portion of the study, a physical model using an energy balance from methane combustion was developed to understand the energy transfer between the three phases of gas, liquid and solid during the hydrate burn. Also this study provides an understanding of the different factors impacting the hydrate's continuous burn, such as the amount of water vapor in the flame. The theoretical study revealed how the water layer thickness on the hydrate surface, and its effect on the temperature gradient through the dissociated zone, plays a significant role in the hydrate dissociation rate and methane release rate. Motivated by the above mentioned observation from the theoretical analysis, a 1-D two-phase numerical simulation based on a moving front model for hydrate dissociation from a thermal source was developed. This model was focused on the dynamic growth of the dissociated zone and its effect on the dissociation rate. The model indicated that the rate of hydrate dissociation with a thermal source is a function of the dissociated zone thickness. It shows that in order for a continuous dissociation and methane release, some of the water from the dissociated zone needs to be drained. The results

  9. Hydration of mechanically activated granulated blast furnace slag

    NASA Astrophysics Data System (ADS)

    Kumar, Rakesh; Kumar, Sanjay; Badjena, S.; Mehrotra, S. P.

    2005-12-01

    Ground granulated blast furnace slag (GGBFS) is known to possess latent hydraulic activity, i.e., it shows cementitious properties when in contact with water over a long period of time. Results are presented in this article to show that, in sharp contrast to published literature on the hydration of neat GGBFS, the complete hydration of slag is possible in a short time (days), even without a chemical activator. This is achieved if the slag used for hydration is mechanically activated, using an attrition mill. The nature of the hydration product of the mechanically activated slag depends not only on the initial specific surface area (SSA) of the slag but also on the surface activation, as manifested by the change in the zeta potential ( ?) of the slag during the milling process. Depending upon the SSA and the ?, the hydration product changed from nonreacted slag with high porosity (slag SSA < 0.3 m2/g, ?>-29 mV) to hydrated slag with a compact structure (SSA=0.3 to 0.4 m2/g, ?=-29 to -31 mV), and, finally, to fully hydrated slag with high porosity (SSA>0.4 m2/g, ? ˜ 26 mV). Unlike the poorly crystalline hydration product formed by the nonactivated slag, even after prolonged hydration for years, the hydration product of mechanically activated slag was crystalline in nature. The crystallinity of the product improved as the duration of the mechanical activation increased. The calcium-silicate-hydrate (C-S-H) phases present in the slag hydration product, characterized by a Ca/Si ratio of 0.7 to 1.5, were similar to those found for the hydraulic cement binder, except for the presence of Mg and Al as impurities. In addition, the presence of a di-calcium-silicate-hydrate phase ( ?-C2SH), which normally forms under hydrothermal conditions, and a Ca-deficient and Si-Al-rich phase (average Ca/Si mole ratio < 0.1 and Si/Al ˜ 3) is indicated, especially in the hydration product of slag that was activated for a longer time.

  10. Dietary Sodium

    MedlinePLUS

    Table salt is made up of the elements sodium and chlorine - the technical name for salt is sodium chloride. Your body needs some sodium to work properly. ... to healthy eating is choosing foods low in salt and sodium. Doctors recommend you eat less than ...

  11. Vibrational spectra of the two hydrates of strontium oxalate.

    PubMed

    D'Antonio, Maria C; Torres, María M; Palacios, Daniel; González-Baró, Ana C; Baran, Enrique J

    2015-02-25

    The infrared and Raman spectra of the two hydrates of strontium oxalate, SrC2O4?H2O and SrC2O4?2H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the related calcium oxalates and other previously investigated metallic oxalates. PMID:25238188

  12. Calcium oxalate crystallization kinetics from calorimetric measurements

    Microsoft Academic Search

    O. Söhnel; M. Kroupa; G. Franková; V. Velich

    1997-01-01

    The kinetics of calcium oxalate monohydrate precipitation effected by mixing aqueous solutions of calcium chloride and sodium oxalate together in the stoichiometric ratio at 25 and 37°C, were studied using an isoperibolic reaction twin calorimeter. A method for inferring the crystal growth kinetic parameters from experimental progress curve giving the time development of the integral heat evolved during the precipitation

  13. EFFECTS OF pH AND OF VARIOUS CONCENTRATIONS OF SODIUM, POTASSIUM, AND CALCIUM CHLORIDE ON MUSCULAR ACTIVITY OF THE ISOLATED CROP OF PERIPLANETA AMERICANA (ORTHOPTERA)

    PubMed Central

    Griffiths, James T.; Tauber, Oscar E.

    1943-01-01

    1. Twenty-five solutions which contained KCl (0.0, 0.2, 0.4, 0.6, and 0.8 gm. per liter), in combination with CaCl2 (0.0, 0.2, 0.4, 0.6, and 0.8 gm. per liter), 10.0 gm. of NaCl, and 0.2 gm. of NaHCO3 per liter of solution were tested in order to determine satisfactory KCl/CaCl2 ratios in an insect physiological salt mixture for the maintenance of muscular activity by the isolated crop of the American roach. Satisfactory activity products (0.390 to 0.549) were obtained in seven mixtures with KCl/CaCl2 ratios of 0.2/0.2, 0.4/0.4, 0.6/0.6, 0.8/0.8, 0.2/0.4, 0.4/0.6, and 0.6/0.8, expressed as gram per liter. These ratios lie between 0.50 and 1.00. In solutions which contained calcium, but no potassium, approximately 50 per cent of the crops exhibited an initial tone increase and were arrested in rigor. See Fig. 2. In solutions which contained potassium, but no calcium, all crops showed an initial loss of tone and arrest in relaxation. See Fig. 2. 2. Seven KCl/CaCl2 ratios (see paragraph 1 above) were tested with eight NaCl concentrations (1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, and 1.8 per cent) at a pH of 8.0. In these mixtures, the ones with KCl/CaCl2 ratios of less than 1.0 produced higher activity products than those with ratios equal to 1.00. The highest average activity product (0.849) was obtained in the solutions with 0.2 gm. of KCl and 0.4 gm. of CaCl2 per liter. 3. Four KCl/CaCl2 ratios (0.2/0.2, 0.4/0.4, 0.2/0.4, and 0.4/0.6 gm. per liter) were tested with 1.4, 1.5, and 1.6 per cent NaCl at a pH of 7.5. When analyzed with data from comparable solutions at a pH of 8.0, it was found that 1.4 per cent NaCl afforded an optimum environment for isolated crop activity. 4. Effects of hydrogen and hydroxyl ion concentrations were studied at pH values of 6.8, 7.5, 8.0, and 8.9. The highest average activity product, 1.011, was produced at a pH of about 8.0. 5. A satisfactory physiological salt solution for the isolated foregut of the American roach, Periplaneta americana, would contain 14.0 gm. of NaCl, 0.4 gm. of CaCl2, 0.2 gm. of KCl, and 0.2 gm. of NaHCO3 per liter of solution. This mixture should have a pH value between 7.8 and 8.2. 6. Durations of crop activity extending over periods as long as 25 hours were quite common, and several crops maintained contractions for more than 30 hours. The greatest longevity was for crop 814, from a female, which continued activity for slightly more than 47 hours. 7. A significant difference between the activity products of the crops from males and the crops from females was recorded. Although there was not a significant difference in the amount of food ingested by males and females, 12 hours after feeding there was more food in the females' crops, and the food progressed more rapidly through the males' crops than through the females'. In addition, crops from the two sexes reacted differently to the effects of day old solutions. This sex difference is apparently related to an inherently increased activity of the crop from the male roach. PMID:19873366

  14. c-Fos expression in ouabain-treated vascular smooth muscle cells from rat aorta: evidence for an intracellular-sodium-mediated, calcium-independent mechanism

    PubMed Central

    Taurin, Sebastien; Dulin, Nickolai O; Pchejetski, Dimitri; Grygorczyk, Ryszard; Tremblay, Johanne; Hamet, Pavel; Orlov, Sergei N

    2002-01-01

    In this study, we examined the effect of Na+–K+ pump inhibition on the expression of early response genes in vascular smooth muscle cells (VSMC) as possible intermediates of the massive RNA synthesis and protection against apoptosis seen in ouabain-treated VSMC in our previous experiments. Incubation of VSMC with ouabain resulted in rapid induction of c-Fos protein expression with an approximately sixfold elevation after 2 h of incubation. c-Jun expression was increased by approximately fourfold after 12 h, whereas expression of activating transcription factor 2, cAMP/Ca2+ response element binding protein (CREB)-1 and c-Myc was not altered. Markedly augmented c-Fos expression was also observed under Na+–K+ pump inhibition in potassium-depleted medium. Na+–K+ pump inhibition triggered c-Fos expression via elevation of the [Na+]i/[K+]i ratio. This conclusion follows from experiments showing the lack of effect of ouabain on c-Fos expression in high-potassium-low-sodium medium and from the comparison of dose responses of Na+–K+ pump activity, [Na+]i and [K+]i content and c-Fos expression to ouabain. A fourfold increment of c-Fos mRNA was revealed 30 min following addition of ouabain to the incubation medium. At this time point, treatment with ouabain resulted in an approximately fourfold elevation of [Na+]i but did not affect [K+]i. Augmented c-Fos expression was also observed under VSMC depolarization in high-potassium medium. Increments in both c-Fos expression and 45Ca uptake in depolarized VSMC were abolished under inhibition of L-type Ca2+ channels with 0.1 ?M nicardipine. Ouabain did not affect the free [Ca2+]i or the content of exchangeable [Ca2+]i. Ouabain-induced c-Fos expression was also insensitive to the presence of nicardipine and [Ca2+]o, as well as chelators of [Ca2+]o (EGTA) and [Ca2+]i (BAPTA). The effect of ouabain and serum on c-Fos expression was additive. In contrast to serum, however, ouabain failed to activate the Elk-1, serum response factor, CREB and activator protein-1 transcription factors identified within the c-Fos promoter. These results suggest that Na+–K+ pump inhibition triggers c-Fos expression via [Na+]i-sensitive [Ca2+]i-independent transcription factor(s) distinct from factors interacting with known response elements of this gene promoter. PMID:12231642

  15. The cardiac sodium pump: structure and function

    Microsoft Academic Search

    Alicia A. McDonough; Jeffrey B. Velotta; Robert H. G. Schwinger; Kenneth D. Philipson; Robert A. Farley

    2002-01-01

    Cardiac sodium pumps (Na,K-ATPase) influence cell calcium and contractility by generating the Na + gradient driving Ca ++ extrusion via the Na +\\/Ca ++ exchanger (NCX), and are the receptors for cardiac glycosides such as digitalis which increases cardiac contractility by decreasing the Na + gradient driving Ca ++ extrusion. There are multiple isoforms of the sodium pump expressed in

  16. Jejunal calcium permeability in laying hens during egg formation

    E-print Network

    Paris-Sud XI, Université de

    Jejunal calcium permeability in laying hens during egg formation Y. NYS, P. MONGIN Station de to water, calcium, potassium, sodium and chloride was measured in the immature pullet and then in the laying hen before and during egg-shell calcification by an in vivo perfusion procedure. Jejunal calcium

  17. The influence of additives and metal rods on the nucleation and growth of gas hydrates.

    PubMed

    Li, Jinping; Liang, Deqing; Guo, Kaihua; Wang, Ruzhu

    2005-03-01

    A major technical issue in industrial applications of the gas hydrate storage process is to develop a practical means for rapid hydrate formation. In this paper, the formation processes of HCFC141b (CH(3)CCl(2)F) gas hydrate in a column of water with additives and with an iron rod that was placed in the center of the column have been studied to reveal the influence of the additives and the iron rod on the nucleation and growth of the gas hydrate. The water solution column, in a cylindrical glass container, was placed in a thermostatic bath at 274.15-280.15 K and under atmospheric pressure. The experimental results show that, compared to the pure water and the HCFC141b system, the properly placed iron rod combined with proper concentrations of lauryl sodium sulfonate, lauryl sodium sulfate, and sodium dodecylbenzenesulfonate-6 considerably reduces the hydrate nucleation time and promotes formation speed. The formation rate of HCFC141b gas hydrate increases with increasing concentration of sodium dodecylbenzenesulfonate-6 in the water solution, while the addition of potassium oxalate monohydrate in water has shown no effect on the nucleation and growth of HCFC141b gas hydrate. Under the experimental conditions, both the anion surfactants and the iron rod strongly induce the first nucleation of HCFC141b gas hydrate, while the following growth of the HCFC141b gas hydrate is primarily influenced by the anion surfactant. This experiment suggests a new way of fast formation of clathrate hydrate, which may be much easier for practical application of the gas hydrate for cold storage in air conditioning systems. PMID:15694442

  18. Mallik Gas Hydrate Sample

    USGS Multimedia Gallery

    A sample of gas hydrates collected from Mallik, Canada. Gas hydrates are naturally-occurring “ice-like” combinations of natural gas and water that have the potential to provide an immense resource of natural gas from the world’s oceans and polar regions....

  19. Gas Hydrates Burning

    USGS Multimedia Gallery

    An image of gas hydrates burning. Gas hydrates are naturally-occurring “ice-like” combinations of natural gas and water that have the potential to provide an immense resource of natural gas from the world’s oceans and polar regions....

  20. 40 CFR 721.2076 - D-Glucuronic acid, polymer with 6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium salt. 721...6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium salt. ...6-deoxy-L-mannose and D-glucose, acetate, calcium magnesium potassium sodium salt...

  1. Hydration rate of obsidian.

    PubMed

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years. PMID:17782901

  2. Excitation-Contraction Coupling and Extracellular Calcium Transients in Rabbit Atrium: Reconstruction of Basic Cellular Mechanisms

    Microsoft Academic Search

    D. W. Hilgemann; D. Noble

    1987-01-01

    Interactions of electrogenic sodium-calcium exchange, calcium channel and sarcoplasmic reticulum in the mammalian heart have been explored by simulation of extracellular calcium transients measured with tetramethylmurexide in rabbit atrium. The approach has been to use the simplest possible formulations of these mechanisms, which together with a minimum number of additional mechanisms allow reconstruction of action potentials, intracellular calcium transients and

  3. Reactivity of iron carbonyl complexes in a hydrated sodium-Y zeolite matrix and catalysis of the resulting hydride anion HFe/sub 3/(CO)/sub 11//sup -/ for water-gas-shift reaction

    SciTech Connect

    Iwamoto, M.; Nakamura, S.; Kusano, H.; Kagawa, S.

    1986-10-09

    Iron carbonyls Fe(CO)/sub 5/, Fe/sub 2/(CO)/sub 9/, and Fe/sub 3/(CO)/sub 12/ have been introduced into a hydrated Na-Y zeolite. Fe(CO)/sub 5/ was only weakly adsorbed on the zeolite. Fe/sub 2/(CO)/sub 9/ and Fe/sub 3/(CO)/sub 12/ were reactive in the hydrated zeolite cages to yield a hydride anion species HFe/sub 3/(CO)/sub 11//sup -/ which was characterized by IR absorption bands at 2044, 1987, 1950, and 1645 cm/sup -1/, UV-vis spectrum at 540 nm, and gas-phase analyses. The red shift of absorption band of the bridging carbonyl indicated ionic interaction of a bridging carbonyl with an Al/sup 3 +/ ion in the zeolite matrix. The formation of the anion species was not observed in a dehydrated Na-Y zeolite, indicating the importance of water or a surface hydroxyl group n the reaction. The reaction course from di- or trinuclear iron carbonyl to the hydride anion has been studied by an ESR technique. Fe/sub 2/(CO)/sub 8//sup -/, Fe(CO)/sub 4//sup -/, and Fe/sub 3/(CO)/sub 11//sup -/ species were detected as intermediates, and reaction schemes have been proposed. The resulting HFe/sub 3/(CO)/sub 11//sup -/ was stable at or below 413 K both in a vacuum or in a CO atmosphere. Above this temperature it was gradually decomposed. Catalytic activity of the HFe/sub 3/(CO)/sub 11//sup -/ species was examined for water-gas-shift reaction at 333-453 K and atmospheric pressure. The activity was very high and comparable to that reported in the homogeneous phase at high pressure. Kinetics and spectroscopic studies indicated that the reaction between HFe/sub 3/(CO)/sub 11//sup -/ and H/sub 2/O would be rate-determining.

  4. New high-capacity, calcium-based sorbents, calcium silicate sorbents. Final report

    SciTech Connect

    Kenney, M.E.

    1996-02-28

    A search is being carried out for new calcium-based SO{sub 2} sorbents for induct injection. More specifically, a search is being carried out for induct injection calcium silicate sorbents that are highly cost effective. The current year objectives include the study of sorbents made by hydrating ordinary or Type I portland cement or portland cement clinker (a cement intermediate) under carefully selected conditions. Results of this study show that an excellent portland cement sorbent can be prepared by milling cement at 120{degrees}C at 600 rpm for 15 minutes with MgO-stabilized ZrO{sub 2} beads. They also show that clinker, which is cheaper than cement can be used interchangeably with cement as a starting material. Further, it is clear that while a high surface area may be a desirable property of a good sorbent, it is not a requisite property. Among the hydration reaction variables, milling time is highly important, reaction temperature is important and stirring rate and silicate-to-H{sub 2}O ratio are moderately important. The components of hydrated cement sorbent are various combinations of C-S-H, calcium silicate hydrate:Ca(OH){sub 2};AFm. a phase in hydrated cement.

  5. Transformations in methane hydrates.

    PubMed

    Chou, I M; Sharma, A; Burruss, R C; Shu, J; Mao, H; Hemley, R J; Goncharov, A F; Stern, L A; Kirby, S H

    2000-12-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A and volume V = 5051.3(13) A(3); structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A, c = 9.992(3) A, and V = 1241.9(5) A(3). The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins. PMID:11087836

  6. NCLX: The Mitochondrial Sodium Calcium Exchanger

    PubMed Central

    Boyman, Liron; Williams, George S. B.; Khananshvili, Daniel; Sekler, Israel; Lederer, W. J.

    2013-01-01

    The free Ca2+ concentration within the mitochondrial matrix ([Ca2+]m) regulates the rate of ATP production and other [Ca2+]m sensitive processes. It is set by the balance between total Ca2+ influx (through the mitochondrial Ca2+ uniporter (MCU) and any other influx pathways) and the total Ca2+ efflux (by the mitochondrial Na+/Ca2+ exchanger and any other efflux pathways). Here we review and analyze the experimental evidence reported over the past 40 years which suggest that in the heart and many other mammalian tissues a putative Na+/Ca2+ exchanger is the major pathway for Ca2+ efflux from the mitochondrial matrix. We discuss those reports with respect to a recent discovery that the protein product of the human FLJ22233 gene mediates such Na+/Ca2+ exchange across the mitochondrial inner membrane. Among its many functional similarities to other Na+/Ca2+ exchanger proteins is a unique feature: it efficiently mediates Li+/Ca2+ exchange (as well as Na+/Ca2+ exchange) and was therefore named NCLX. The discovery of NCLX provides both the identity of a novel protein and new molecular means of studying various unresolved quantitative aspects of mitochondrial Ca2+ movement out of the matrix. Quantitative and qualitative features of NCLX are discussed as is the controversy regarding the stoichiometry of the NCLX Na+/Ca2+ exchange, the electrogenicity of NCLX, the [Na+]i dependency of NCLX and the magnitude of NCLX Ca2+ efflux. Metabolic features attributable to NCLX and the physiological implication of the Ca2+ efflux rate via NCLX during systole and diastole are also briefly discussed. PMID:23538132

  7. Nitric oxide production by mouse renal tubules can be increased by a sodium-dependent mechanism

    Microsoft Academic Search

    Stephen Kempson; Nathan Thompson; Laura Pezzuto; H. Glenn Bohlen

    2007-01-01

    Renal tubules process large amounts of NaCl that other investigators indicate increases tubular generation of nitric oxide. We questioned whether medullary or superficial cortical tubules would have the greater increase in nitric oxide concentration, [NO], when stressed by sodium and if the sodium\\/calcium exchanger was involved. Sodium stress in proximal tubules is due to the large amount of sodium absorbed

  8. Maintenance of serum calcium after total thyroparathyroidectomy.

    PubMed

    Kerr, D; Skinner, D W; Hosking, D J; Bradley, P J; Salama, F D

    1990-10-01

    We have studied calcium regulation in 11 consecutive patients undergoing radical surgery for upper aerodigestive tract malignancy. Eight patients received postoperative parenteral nutrition including calcium (19 mmol/day) and tri-iodothyronine (30 micrograms/day) supplementation. Three patients received enteral nutrition with calcium (70 mmol/day), 1.25 dihydroxycholecalciferol (1 microgram) and thyroxine (150 micrograms/day) via a nasogastric tube. Mean (SEM) corrected calcium fell from 2.42 (0.013) to 2.03 (0.036) mmol/l after 24 h (P less than 0.01). Replacement therapy generally maintained the serum calcium above 2.0 mmol/l. However, values were associated with only one episode of tetany. Phosphate increased from 1.10 (0.05) to 1.79 (0.11) mmol/l, 7-9 days postoperatively (P less than 0.001). Tubular calcium reabsorption fell and urinary calcium excretion rose, consistent with loss of parathyroid hormone (PTH) action on the distal nephron. However, the renal leak of calcium can be considerably reduced by concomitant salt depletion. This enhances proximal tubular sodium and calcium reabsorption thereby limiting calcium delivery to the distal nephron. This offsets the consequences of the loss of PTH which normally regulates distal calcium reabsorption. PMID:2120083

  9. Improved evidence for the existence of an intermediate phase during hydration of tricalcium silicate

    SciTech Connect

    Bellmann, Frank, E-mail: frank.bellmann@uni-weimar.d [Institute for Building Materials Science, Bauhaus University Weimar, 99423 Weimar (Germany); Damidot, Denis [Ecole des Mines de Douai, Civil and Environmental Engineering Department, 941 rue Charles Bourseul, BP 10838, 59508 Doua cedexi (France); Moeser, Bernd [Institute for Building Materials Science, Bauhaus University Weimar, 99423 Weimar (Germany); Skibsted, Jorgen [Instrument Center for Solid-State NMR Spectroscopy and Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University DK-8000 Aarhus C (Denmark)

    2010-06-15

    Tricalcium silicate (Ca{sub 3}SiO{sub 5}) with a very small particle size of approximately 50 nm has been prepared and hydrated for a very short time (5 min) by two different modes in a paste experiment, using a water/solid-ratio of 1.20, and by hydration as a suspension employing a water/solid-ratio of 4000. A phase containing uncondensed silicate monomers close to hydrogen atoms (either hydroxyl groups or water molecules) was formed in both experiments. This phase is distinct from anhydrous tricalcium silicate and from the calcium-silicate-hydrate (C-S-H) phase, commonly identified as the hydration product of tricalcium silicate. In the paste experiment, approximately 79% of silicon atoms were present in the hydrated phase containing silicate monomers as determined from {sup 29}Sileft brace{sup 1}Hright brace CP/MAS NMR. This result is used to show that the hydrated silicate monomers are part of a separate phase and that they cannot be attributed to a hydroxylated surface of tricalcium silicate after contact with water. The phase containing hydrated silicate monomers is metastable with respect to the C-S-H phase since it transforms into the latter in a half saturated calcium hydroxide solution. These data is used to emphasize that the hydration of tricalcium silicate proceeds in two consecutive steps. In the first reaction, an intermediate phase containing hydrated silicate monomers is formed which is subsequently transformed into C-S-H as the final hydration product in the second step. The introduction of an intermediate phase in calculations of the early hydration of tricalcium silicate can explain the presence of the induction period. It is shown that heterogeneous nucleation on appropriate crystal surfaces is able to reduce the length of the induction period and thus to accelerate the reaction of tricalcium silicate with water.

  10. Optimizing the calcium content of a copolymer acrylamide gel matrix for dark-grown seedlings.

    PubMed

    Myers, P N; Mitchell, C A

    1998-11-01

    A copolymer acrylamide acrylate gel was investigated as the sole root matrix for dark-grown seedlings of soybean (Glycine max Merr. 'Century 84'). Increasing Ca2+ in the hydrating solution of the hydrogel from 1 to 10 mM decreased its water-holding capacity from 97 to 46 mL g-1, yet water potential of the medium remained high, sufficient for normal plant growth at all Ca2+ concentrations tested. Elongation rate of dark-grown soybean seedlings over a 54-hour period was 0.9, 1.5, and 1.8 mm h-1 with 1.0, 2.5, or 5.0 mM Ca2+, respectively, but did not increase with further increases in Ca2+ concentration. Further study revealed that Na+ was released from the hydrogel medium and was taken up by the seedlings as Ca2+ increased in the medium. In dry hypocotyl tissue, sodium content correlated negatively with calcium content. Despite the presence of Na+ in the hydrogel, seedling growth was normal when adequate Ca2+ was added in the hydrating solution. Acrylamide hydrogels hold good potential as a sole growth matrix for short-term experiments with dark-grown seedlings without irrigation. PMID:11542673

  11. Control of SO\\/subx\\/ emissions by in-furnace sorbent injection: Carbonates vs. hydrates

    Microsoft Academic Search

    G. H. Newton; D. J. Harrison; G. D. Silcox; D. W. Pershing

    1986-01-01

    High temperature, isothermal data on SOâ capture by calcium based sorbents were obtained in a dispersed-phase reactor for limestones, dolomites, hydrated calcitic limes, and hydrated dolomitic lines as a function of Ca\\/S molar ratio, temperature, and SOâ partial pressure. The experimental results indicate that SOâ capture is approximately linearly dependent on Ca\\/S molar ratio and relatively insensitive to SOâ partial

  12. A kinetic study of delayed ettringite formation in hydrated portland cement paste

    Microsoft Academic Search

    Yan Fu; Ping Gu; Ping Xie; J. J. Beaudoin

    1995-01-01

    Results of a kinetic study of delayed ettringite formation in hydrated Portland cement paste by XRD analysis over the temperature range 5 to 85 °C are reported. Two competitive reactions in terms of gypsum consumption are discussed. These involve both C?S?H gel and the hydrated calcium aluminates. An increase in temperature apparently accelerates sulphate absorption rate by C? S?H gel.

  13. Initial hydration reactions and mechanisms of delayed ettringite formation in Portland cements

    Microsoft Academic Search

    H.-J. Kuzel

    1996-01-01

    The aluminate hydration reactions in Portland cements were followed by X-ray diffraction. Using a computerized focusing Huber-Guinier diffractometer, the patterns were obtained from the pastes directly, without preliminary drying or grinding. It is shown that the widely accepted theories on the hydration of C3A in the presence of calcium sulfate cannot be applied generally to commercial Portland cements. Only in

  14. Impact of admixtures on the hydration kinetics of Portland cement

    SciTech Connect

    Cheung, J., E-mail: Josephine.H.Cheung@grace.com [W.R. Grace, 62 Whittemore Avenue, Cambridge MA 02140 (United States); Jeknavorian, A. [W.R. Grace, 62 Whittemore Avenue, Cambridge MA 02140 (United States); Roberts, L. [Roberts Consulting Group LLC, 44 Windsor Avenue, Acton MA 01720 (United States); Silva, D. [W.R. Grace, 62 Whittemore Avenue, Cambridge MA 02140 (United States)

    2011-12-15

    Most concrete produced today includes either chemical additions to the cement, chemical admixtures in the concrete, or both. These chemicals alter a number of properties of cementitious systems, including hydration behavior, and it has been long understood by practitioners that these systems can differ widely in response to such chemicals. In this paper the impact on hydration of several classes of chemicals is reviewed with an emphasis on the current understanding of interactions with cement chemistry. These include setting retarders, accelerators, and water reducing dispersants. The ability of the chemicals to alter the aluminate-sulfate balance of cementitious systems is discussed with a focus on the impact on silicate hydration. As a key example of this complex interaction, unusual behavior sometimes observed in systems containing high calcium fly ash is highlighted.

  15. Dalteparin sodium.

    PubMed

    Pineo, G F; Hull, R D

    2001-08-01

    Dalteparin sodium (Fragmin, Pharmacia Corporation) is a low molecular weight heparin (LMWH) with a mean molecular weight of approximately 5000 Da. As with the other LMWHs, dalteparin sodium has certain advantages over unfractionated heparin (UFH), most important of which are improved bio-availability by sc. injection, a prolonged antithrombotic activity which is highly correlated with body weight permitting the o.d. administration of the drug. Dalteparin sodium has been subjected to a large number of well-designed randomised clinical trials for the prevention and treatment of thrombotic disorders. Based on data from the randomised clinical trials, dalteparin sodium has been approved internationally for a wide spectrum of clinical indications (e.g., prevention of thromboembolic events after surgery). Dalteparin sodium has also been studied in randomised controlled trials in the maintenance of graft patentcy following peripheral vascular surgery, in place of warfarin for the long-term treatment of patients presenting with deep vein thrombosis (DVT), in the prevention of upper extremity thrombosis in patients with indwelling portacath devices and in pregnant patients with a history of previous venous thromboembolism with or without thrombophilia. Dalteparin sodium has been compared with heparin for the prevention of thrombotic complications during haemodyalisis and haemofiltration. These studies have shown promising results but further work is required before dalteparin sodium can be recommended for these indications. PMID:11585001

  16. HYDRATE CORE DRILLING TESTS

    SciTech Connect

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

    2002-11-01

    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate formation comprised of coarse, large-grain sand in ice. Results with this core showed that the viscosity of the drilling fluid must also be carefully controlled. When coarse sand was being cored, the core barrel became stuck because the drilling fluid was not viscous enough to completely remove the large grains of sand. These tests were very valuable to the project by showing the difficulties in coring permafrost or hydrates in a laboratory environment (as opposed to a field environment where drilling costs are much higher and the potential loss of equipment greater). Among the conclusions reached from these simulated hydrate coring tests are the following: Frozen hydrate core samples can be recovered successfully; A spring-finger core catcher works best for catching hydrate cores; Drilling fluid can erode the core and reduces its diameter, making it more difficult to capture the core; Mud must be designed with proper viscosity to lift larger cuttings; and The bottom 6 inches of core may need to be drilled dry to capture the core successfully.

  17. Effect of sodium salt of naphthalene-formaldehyde polycondensate on ettringite formation

    Microsoft Academic Search

    Eisa E. Hekal; Essam A. Kishar

    1999-01-01

    The suspension hydration of C3A with gypsum (in the molar ratio of 1:3) was investigated at room temperature and water\\/solid ratio of 4. The hydration was carried out in presence of 0, 1, and 3% sodium salt of naphthalene-formaldehyde polycondensate and the mixes were designated as I, II, and III, respectively. The only hydration product formed in the presence and

  18. Gas Hydrates: It's A Gas!

    NSDL National Science Digital Library

    In this activity, students will investigate the occurrence of gas hydrates on the ocean floor. They will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is gas hydrates. Students will discover that Earth's climate changes, and how the greenhouse effect works. They will also learn about the potential of hydrates as a major new energy resource and explore the conditions under which hydrates form.

  19. Calcium - urine

    MedlinePLUS

    ... much calcium Too much production of parathyroid hormone (PTH) by the parathyroid glands in the neck (hyperparathyroidism) ... glands in the neck do not produce enough PTH (hypoparathyroidism) Use of a water pill called a ...

  20. Calcium orthophosphates

    PubMed Central

    Dorozhkin, Sergey V.

    2011-01-01

    The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. This type of materials is of special significance for human beings, because they represent the inorganic part of major normal (bones, teeth and antlers) and pathological (i.e., those appearing due to various diseases) calcified tissues of mammals. For example, atherosclerosis results in blood vessel blockage caused by a solid composite of cholesterol with calcium orthophosphates, while dental caries and osteoporosis mean a partial decalcification of teeth and bones, respectively, that results in replacement of a less soluble and harder biological apatite by more soluble and softer calcium hydrogenphosphates. Therefore, the processes of both normal and pathological calcifications are just an in vivo crystallization of calcium orthophosphates. Similarly, dental caries and osteoporosis might be considered an in vivo dissolution of calcium orthophosphates. Thus, calcium orthophosphates hold a great significance for humankind, and in this paper, an overview on the current knowledge on this subject is provided. PMID:23507744

  1. Calcium Hydroxylapatite

    PubMed Central

    Yutskovskaya, Yana Alexandrovna; Philip Werschler, WM.

    2015-01-01

    Background: Calcium hydroxylapatite is one of the most well-studied dermal fillers worldwide and has been extensively used for the correction of moderate-to-severe facial lines and folds and to replenish lost volume. Objectives: To mark the milestone of 10 years of use in the aesthetic field, this review will consider the evolution of calcium hydroxylapatite in aesthetic medicine, provide a detailed injection protocol for a global facial approach, and examine how the unique properties of calcium hydroxylapatite provide it with an important place in today’s market. Methods: This article is an up-to-date review of calcium hydroxylapatite in aesthetic medicine along with procedures for its use, including a detailed injection protocol for a global facial approach by three expert injectors. Conclusion: Calcium hydroxylapatite is a very effective agent for many areas of facial soft tissue augmentation and is associated with a high and well-established safety profile. Calcium hydroxylapatite combines high elasticity and viscosity with an ability to induce long-term collagen formation making it an ideal agent for a global facial approach. PMID:25610523

  2. 2007 Minerals Yearbook U.S. Department of the Interior

    E-print Network

    minerals of commercial importance in the United States were colemanite (hydrated calcium borate), kernite (hydrated sodium borate), tincal, and ulexite (hydrated sodium calcium borate) (table 2). Boron compounds% of the borates used by industry worldwide, the sodium borates, borax and kernite; the calcium borate, colemanite

  3. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  4. Selective electrochemical reactions of an alumina hydrate crystallization inhibitor

    Microsoft Academic Search

    Nicolas-Alexandre Bouchard; Anne Brisach-Wittmeyer; Raymond Breault; Hugues Ménard

    2007-01-01

    Selective reactions of catechol have been studied in regard to its inhibition properties towards alumina hydrate crystallization.\\u000a Electrochemical reactions of the inhibitor leading to products without inhibition behaviour have been obtained using different\\u000a conditions. First, a pure sodium hydroxide solution (1.0 M NaOH) was used to electrochemically react the catechol. The inhibitor\\u000a reactions were then carried out in both saturated and

  5. Expansive properties of ettringite in a mixture of calcium aluminate cement, Portland cement and ?-calcium sulfate hemihydrate

    Microsoft Academic Search

    Cecilie Evju; Staffan Hansen

    2001-01-01

    The hydration of a paste consisting of 25 wt.% calcium aluminate cement, 12.5 wt.% Portland cement, 12.5 wt.% ?-calcium sulfate hemihydrate and 50 wt.% water was studied at 20°C and 100% relative humidity, using in-situ synchrotron X-ray powder diffraction, isothermal conduction calorimetry and dilatometric measurements. Initially, gypsum and ettringite form, while hemihydrate is consumed (0–45 min). Ettringite then continues forming

  6. Allosteric sodium in class A GPCR signaling

    PubMed Central

    Katritch, Vsevolod; Fenalti, Gustavo; Abola, Enrique E.; Roth, Bryan L.; Cherezov, Vadim; Stevens, Raymond C.

    2014-01-01

    Despite their functional and structural diversity, G protein-coupled receptors (GPCRs) share a common mechanism of signal transduction via conformational changes in the seven-transmembrane (7TM) helical domain. New major insights into this mechanism come from the recent crystallographic discoveries of a partially hydrated sodium ion that is specifically bound in the middle of the 7TM bundle of multiple class A GPCRs. This review discusses the remarkable structural conservation and distinct features of the Na+ pocket in this most populous GPCR class, as well as the conformational collapse of the pocket on receptor activation. New insights help to explain allosteric effects of sodium on GPCR agonist binding and activation, and sodium’s role as a potential co-factor in class A GPCR function. PMID:24767681

  7. The real-time, in situ monitoring of calcium oxalate and brushite precipitation using magnetoelastic sensors

    Microsoft Academic Search

    Nikolaos Bouropoulos; Dimitris Kouzoudis; Craig Grimes

    2005-01-01

    Reactions resulting in the precipitation of calcium oxalate, and brushite formation were monitored in situ using magnetoelastic sensors. These salts frequently occur in pathological precipitation in higher mammals. Calcium oxalate hydrates and brushite were formed by mixing anionic and cationic reactant solutions, with the resulting precipitation reaction starting immediately and mass loading the sensor. Magnetoelastic sensors operate on a remote

  8. Ris-R-1143(EN) Modelling Calcium Carbonate Deposition

    E-print Network

    Risø-R-1143(EN) CRACK2 - Modelling Calcium Carbonate Deposition from Bicarbonate Solution in Cracks of bicarbonate solution in a crack connecting the ends of a row of such columns. The cementitious material is simulated as calcium hydroxide mixed with inert material but with sodium hydroxide dissolved in the pore

  9. FORMULATION OF ORAL SUSTAINED RELEASE ACECLOFENAC SODIUM MICROBEADS

    Microsoft Academic Search

    Shivakumar. B

    ABSTACT: The objective of the present study was microencapsulate the Aceclofenac sodium ( NSAIDs) by ionotropic gelation technique by using sodium alginate as hydrophilic carrier in various proportions and examines the influences of various process parameters like drug: polymer ratio, concentration of calcium chloride, stirring speed and cross-linking time on physicochemical properties of drug loaded microbeads. This system was able

  10. Proper use of sodium bisulfite with minimal salt penetration during brine immersion freezing of shrimp 

    E-print Network

    Broussard, Suzanne Rene

    1988-01-01

    produced undesirable shrimp. Acceptability of flavor, texture and overall acceptability as determined by consumer taste tests for shrimp frozen in calcium/sodium chloride mixtures decreased with storage time. Shrimp frozen in calcium/sodium chloride.... Preliminary data indicates shrimp may absorb up to 3% salt from the brine during freezing, decreasing the sodium chloride concentration of the brine. uptake of salt by shrimp is important not only organoleptically because of the salty taste, but also...

  11. Nutrition, Hydration & Health

    NSDL National Science Digital Library

    2010-01-01

    The following resource is a NFL sponsored, National Science Foundation funded program intended to teach students about scientific concepts by using the popular sport of Football. Each lesson is accompanied by an informative and fast paced video. In this lesson, athletic trainers from the Pittsburgh Steelers explain what NFL players must do to stay hydrated and replenish the essential nutrients needed to maintain good health during rigorous practices.

  12. Methane Recovery from Hydrate-bearing Sediments

    Microsoft Academic Search

    J. Carlos Santamarina; Costas Tsouris

    2011-01-01

    Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. Methane hydrate can be an energy resource, contribute to global warming, or cause seafloor instability. This study placed emphasis on gas recovery from hydrate bearing sediments and related

  13. Hydration-dependent dynamic crossover phenomenon in protein hydration water

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Fratini, Emiliano; Li, Mingda; Le, Peisi; Mamontov, Eugene; Baglioni, Piero; Chen, Sow-Hsin

    2014-10-01

    The characteristic relaxation time ? of protein hydration water exhibits a strong hydration level h dependence. The dynamic crossover is observed when h is higher than the monolayer hydration level hc=0.2-0.25 and becomes more visible as h increases. When h is lower than hc, ? only exhibits Arrhenius behavior in the measured temperature range. The activation energy of the Arrhenius behavior is insensitive to h, indicating a local-like motion. Moreover, the h dependence of the crossover temperature shows that the protein dynamic transition is not directly or solely induced by the dynamic crossover in the hydration water.

  14. Methane Clathrate Hydrate Prospecting

    NASA Technical Reports Server (NTRS)

    Duxbury, N.; Romanovsky, V.

    2003-01-01

    A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas hydrate (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-hydrate sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas hydrate, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.

  15. Controls on calcium isotope fractionation in sedimentary porewaters

    Microsoft Academic Search

    Barbara M. A. Teichert; Nikolaus Gussone; Marta E. Torres

    2009-01-01

    The calcium isotopic composition of porewaters and authigenic carbonates in the anoxic sediments of a convergent continental margin drilled during Ocean Drilling Program (ODP) provides first insight into the different processes that control Ca geochemistry in clastic marine, organic-rich sedimentary environments. In 4 sites drilled during Leg 204 at Hydrate Ridge (Cascadia Margin, offshore Oregon\\/USA), sulfate is consumed during anaerobic

  16. Meteoric calcium

    NASA Astrophysics Data System (ADS)

    Plane, John M. C.

    2011-11-01

    Calcium is found throughout the solar system, the Earth's crust and oceans, and is an essential constituent of cells, shells and bones -- yet it is curiously scarce in the upper atmosphere. John Plane ponders on this 25-year-old mystery.

  17. Project Calcium

    SciTech Connect

    Hurley, J.P.; Benson, S.A.; Erickson, T.A.; Allan, S.E.; Bieber, J.

    1992-09-01

    Fouling problems in utility boilers have been classified into two principal types: high-temperature and low-temperature fouling. A multiclient-sponsored program was initiated at the Energy and Environmental Research Center (EERC) to better understand the causes of low-temperature fouling when burning high-calcium western US coals. The goals of Project Calcium were to define the low-temperature deposition problem, identify the calcium-based components that are responsible for the formation of the deposits, develop ways to predict their formation, and identify possible methods to mitigate the formation of these deposits. To achieve the goals of Project Calcium, detailed sampling of utility boilers and laboratory-scale studies coupled with state-of-the-art methods to determine the inorganic components in coals and coal ash-derived materials were conducted. Boiler Sampling was also performed. The work involved sampling coal, entrained ash, deposits and slags from five full-scale utility boilers combined with detailed advanced characterization of the materials. The results of this work aided in identifying the key phenomena to focus the laboratory studies and in model verification. Field testing was conducted at three utilities.

  18. Rapid gas hydrate formation process

    DOEpatents

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  19. Sodium-calcium interactions under salinity stress 205 SODIUM-CALCIUM INTERACTIONS UNDER SALINITY STRESS

    E-print Network

    Cramer, Grant R.

    level of salinity is dependent upon the concentration and composition of the ions in solution as well as the genotype that is exposed to the salinity. Once the importance of Ca in the external solution was fully in solution (e.g. NaCl). Saline soils are commonly defined as those soils having an EC of 4 dS m-1 or greater

  20. Gas hydrates: technology status report

    SciTech Connect

    Not Available

    1986-01-01

    The DOE Morgantown Energy Technology Center (METC) implemented a gas hydrates R and D program that emphasized an understanding of the resource through (1) an assessment of current technology, (2) the characterization of gas hydrate geology and reservoir engineering, and (3) the development of diagnostic tools and methods. Recovery of natural gas from gas hydrates will be made possible through (1) improved instrumentation and recovery methods, (2) developing the capability to predict production performance, and (3) field verification of recovery methods. Gas hydrates research has focused primarily on geology. As work progressed, areas where gas hydrates are likely to occur were identified, and specific high potential areas were targeted for detailed investigation. A Geologic Analysis System (GAS) was developed. GAS contains approximately 30 software packages and can manipulate and correlate several types of geologic and petroleum data into maps, graphics, and reports. The system also contains all well information currently available from the Alaskan North Slope area. Laboratory research on gas hydrates includes the characterization of the physical system, which focuses on creating synthetic methane hydrates and developing synthetic hydrate cores using tetrahydrofuran (THF), consolidated rock cores, frost base mixtures, water/ice-base mixtures, and water-base mixtures. Laboratory work produced measurements of the sonic velocity and electrical resistivity of these synthetic hydrates. During 1983, a sample from a natural hydrate core recovered from the Pacific coast of Guatemala was tested for these properties by DOE/METC. More recently, natural hydrate samples acquired from the Gulf of Mexico are being tested. Modeling and systems analysis work has focused on the development of GAS and preliminary gas hydrate production models. 23 refs., 18 figs., 6 tabs.

  1. Original article Availability of calcium from skim milk, calcium sulfate

    E-print Network

    Paris-Sud XI, Université de

    Original article Availability of calcium from skim milk, calcium sulfate and calcium carbonate; accepted 19 November 1999) Abstract --Dairy products provide abundant, accessible calcium for humans, while some calcium sulfate-rich mineral waters could provide appreciable amounts of calcium

  2. Investigation of the modulation of glutamate release by sodium channels using neurotoxins

    Microsoft Academic Search

    A. F. X Bicalho; C Guatimosim; M. A. M Prado; M. V Gomez; M. A Romano-Silva

    2002-01-01

    The modulation of neurotransmitter release by calcium channels is well established, yet, sodium channels were regarded mainly as charge carriers. Many lines of evidence suggest a more fine-tuning role played by sodium channels. Using rat cerebrocortical isolated nerve endings (synaptosomes) and two toxins that have separate sites of action on sodium channels and provoke distinct changes in channel kinetics, we

  3. Nutrient effects on the calcium economy: emphasizing the potassium controversy.

    PubMed

    Rafferty, Karen; Heaney, Robert P

    2008-01-01

    The calcium economy is a dynamic state influenced by fluxes in dietary calcium intake, intestinal calcium absorption, and renal calcium conservation. The relationship of selected bone-related nutrients to these calcium fluxes exhibits both constructive and destructive interactions that affect the overall state of calcium balance. The basis of the calcium requirement and the impact of vitamin D, protein, phosphorus, sodium, and caffeine on the calcium economy are reviewed. Against this background, emerging data on potassium are presented. Data from balance studies of healthy white women at midlife were reviewed to assess the effect of diet potassium on the calcium economy under steady-state conditions. Potassium was inversely associated with both urinary calcium excretion and intestinal calcium absorption, yielding no significant net change in calcium balance. In the population reported on here, dairy, meat, and cereal grains together contributed 56%, and fruits and vegetables 44%, of total dietary potassium. To the extent that fruit and vegetable potassium is a surrogate for high bicarbonate, this cohort did not have a dietary intake pattern allowing for measurement or interpretation of the potential effect of a high-bicarbonate-containing diet on long-term steady-state calcium balance. Potassium itself is uniformly well absorbed regardless of the dietary source. Mean 24-h urinary potassium averaged 92% of dietary intake. According to nationwide food consumption surveys, milk is the number 1 single food source of potassium in all age groups in the United States. PMID:18156419

  4. Measuring and modeling thermal conductivity of gas hydrate-bearing sand

    NASA Astrophysics Data System (ADS)

    Huang, Duzi; Fan, Shuanshi

    2005-01-01

    Effective thermal conductivity (ETC) of both tetrahydrofuran (THF) and methane hydrate-bearing sandy porous media was measured by the Hot Disk Thermal Constant Analyser. Thermal conductivity of methane hydrate is 0.575 W m-1 K-1 at 0°C and 6.6 MPa (methane gas pressure), which is close to THF hydrate's 0.51 W m-1 K-1 at 0°C and 0.1 MPa (atmosphere pressure). However, the measured 1 W m-1 K-1 ETC of methane hydrate-bearing sand is significantly lower than that of THF hydrate-bearing sand at ˜2 W m-1 K-1. This is because the methane hydrate formed with a sodium dodecyl sulfate (SDS) solution in sand at our laboratory has a "wall creeping" growth characteristic and consequently a large part of the pores were filled with methane free gas. ETCs of sand containing gas hydrates were also calculated using a renormalization method. The process involves sample partitioning, labeling, initial value assignments, and renormalization calculations. A Monte Carlo analysis was applied to sample laboratory-scale gas hydrate-bearing sand assemblies. We found that the renormalization modeling results agreed well with measured ETCs when each photo of a 1.3 mm × 1.3 mm subsample was divided into 16 or more blocks.

  5. Observation directe de la croissance d'hydrosilicate de calcium sur des surfaces d'alité et de silice par microscopie à force atomique

    NASA Astrophysics Data System (ADS)

    Gauffinet, Sandrine; Finot, Éric; Lesniewska, Eric; Nonat, André

    1998-08-01

    Direct observation of the growth of calcium silicate hydrates, the tricalcium silicate hydration products, at the solid-solution interface were performed by atomic force microscopy. The covering of the surface of alite or silica by a three-dimensional oriented aggregation of nano particles of calcium silicate hydrate is always observed whatever the sample. All observations and quantifications made on calcium silicate growth at the submicronic level are in agreement with the data deduced from the study of the system evolution at the macroscopic level.

  6. Hydration characteristics of tricalcium aluminate phase in mixes containing {beta}-hemihydate and phosphogypsum

    SciTech Connect

    Radwan, M.M. [National Research Center, Dokki, Cairo (Egypt); Heikal, M. [Chemistry Department, Faculty of Science, Zagazig University, Benha Branch, Benha (Egypt)]. E-mail: ayaheikal@hotmail.com

    2005-08-01

    The tricalcium aluminte phase was prepared from pure chemicals on a laboratory scale. Five mixes were formulated from the prepared C{sub 3}A phase, {beta}-hemihydate, phosphogypsum, calcium hydroxide and quartz. Different mixes were hydrated at various time intervals, namely, 6, 24, 72 and 168 h. The kinetics of hydration was measured from chemically combined water and combined lime contents. The phase compositions and microstructures of the hydrated products were studied by X-ray diffraction (XRD), differential thermal analysis (DTA)/TG, scanning electron microscopy (SEM) techniques and FT-IR spectroscopy. This work aimed to study the effect of partial to full substitution of phosphogypsum by {beta}-hemihydate on the hydration characteristics and microstructures of tricalcium aluminte phase. The results showed that the combined lime slightly increases with the increase of amounts of phosphogypsum. The XRD patterns showed the increase in the intensities of monosulphate and different forms of calcium aluminate (C{sub 4}AH{sub 13} and C{sub 4}AH{sub 19}) with phosphogypsum content. Ettringite is less stable than monosulphoaluminate, so it transformed into monosulpho-aluminate after 24 h, which persisted up to 168 h. The mechanism of the hydration process of C{sub 3}A phase in the presence of phosphogypsum proceeds in a similar path as with {beta}-hemihydate. Phosphogypsum reacts with C{sub 3}A in the presence of Ca(OH){sub 2} forming sulphoaluminate hydrates, which are responsible for setting regulation in cementitious system.

  7. Dysbalance of Astrocyte Calcium under Hyperammonemic Conditions

    PubMed Central

    Haack, Nicole; Dublin, Pavel; Rose, Christine R.

    2014-01-01

    Increased brain ammonium (NH4+/NH3) plays a central role in the manifestation of hepatic encephalopathy (HE), a complex syndrome associated with neurological and psychiatric alterations, which is primarily a disorder of astrocytes. Here, we analysed the influence of NH4+/NH3 on the calcium concentration of astrocytes in situ and studied the underlying mechanisms of NH4+/NH3-evoked calcium changes, employing fluorescence imaging with Fura-2 in acute tissue slices derived from different regions of the mouse brain. In the hippocampal stratum radiatum, perfusion with 5 mM NH4+/NH3 for 30 minutes caused a transient calcium increase in about 40% of astrocytes lasting about 10 minutes. Furthermore, the vast majority of astrocytes (?90%) experienced a persistent calcium increase by ?50 nM. This persistent increase was already evoked at concentrations of 1–2 mM NH4+/NH3, developed within 10–20 minutes and was maintained as long as the NH4+/NH3 was present. Qualitatively similar changes were observed in astrocytes of different neocortical regions as well as in cerebellar Bergmann glia. Inhibition of glutamine synthetase resulted in significantly larger calcium increases in response to NH4+/NH3, indicating that glutamine accumulation was not a primary cause. Calcium increases were not mimicked by changes in intracellular pH. Pharmacological inhibition of voltage-gated sodium channels, sodium-potassium-chloride-cotransporters (NKCC), the reverse mode of sodium/calcium exchange (NCX), AMPA- or mGluR5-receptors did not dampen NH4+/NH3-induced calcium increases. They were, however, significantly reduced by inhibition of NMDA receptors and depletion of intracellular calcium stores. Taken together, our measurements show that sustained exposure to NH4+/NH3 causes a sustained increase in intracellular calcium in astrocytes in situ, which is partly dependent on NMDA receptor activation and on release of calcium from intracellular stores. Our study furthermore suggests that dysbalance of astrocyte calcium homeostasis under hyperammonemic conditions is a widespread phenomenon, which might contribute to the disturbance of neurotransmission during HE. PMID:25153709

  8. Removal of phosphate from greenhouse wastewater using hydrated lime.

    PubMed

    Dunets, C Siobhan; Zheng, Youbin

    2014-01-01

    Phosphate (P) contamination in nutrient-laden wastewater is currently a major topic of discussion in the North American greenhouse industry. Precipitation of P as calcium phosphate minerals using hydrated lime could provide a simple, inexpensive method for retrieval. A combination of batch experiments and chemical equilibrium modelling was used to confirm the viability of this P removal method and determine lime addition rates and pH requirements for greenhouse wastewater of varying nutrient compositions. Lime: P ratio (molar ratio of CaMg(OH)?: PO??P) provided a consistent parameter for estimating lime addition requirements regardless of initial P concentration, with a ratio of 1.5 providing around 99% removal of dissolved P. Optimal P removal occurred when lime addition increased the pH from 8.6 to 9.0, suggesting that pH monitoring during the P removal process could provide a simple method for ensuring consistent adherence to P removal standards. A Visual MINTEQ model, validated using experimental data, provided a means of predicting lime addition and pH requirements as influenced by changes in other parameters of the lime-wastewater system (e.g. calcium concentration, temperature, and initial wastewater pH). Hydrated lime addition did not contribute to the removal of macronutrient elements such as nitrate and ammonium, but did decrease the concentration of some micronutrients. This study provides basic guidance for greenhouse operators to use hydrated lime for phosphate removal from greenhouse wastewater. PMID:25176490

  9. Some thermodynamical aspects of protein hydration water

    NASA Astrophysics Data System (ADS)

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H. Eugene; Chen, Sow-Hsin

    2015-06-01

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature.

  10. Some thermodynamical aspects of protein hydration water.

    PubMed

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H Eugene; Chen, Sow-Hsin

    2015-06-01

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature. PMID:26049527

  11. Hydration of small peptides

    NASA Astrophysics Data System (ADS)

    Wyttenbach, Thomas; Liu, Dengfeng; Bowers, Michael T.

    2005-02-01

    The results for the sequential hydration of small peptides (<15 residues) obtained in our group are reviewed and put in perspective with other work published in the literature where appropriate. Our findings are based on hydration equilibrium measurements in a high-pressure drift cell inserted into an electrospray mass spectrometer and on calculations employing molecular mechanics and density functional theory methods. It is found that the ionic functional groups typically present in peptides, the ammonium, guanidinium, and carboxylate groups, are the primary target of water molecules binding to peptides. Whereas the water-guanidinium binding energy is fairly constant at 9 +/- 1 kcal/mol, the water binding energy of an ammonium group ranges from 7 to 15 kcal/mol depending on how exposed the ammonium group is. A five-residue peptide containing an ammonium group is in favorable cases large enough to fully self-solvate the charge, but a pentapeptide containing a guanidinium group is too small to efficiently shield the charge of this much larger ionic group. The water-carboxylate interaction amounts to 13 kcal/mol with smaller values for a shielded carboxylate group. Both water bound to water in a second solvation shell and charge remote water molecules on the surface of the peptide are bound by 7-8 kcal/mol. The presence of several ionic groups in multiply charged peptides increases the number of favorable hydration sites, but does not enhance the water-peptide binding energy significantly. Water binding energies measured for the first four water molecules bound to protonated bradykinin do not show the declining trend typically observed for other peptides but are constant at 10 kcal/mol, a result consistent with a molecule containing a salt bridge with several good hydration sites. Questions regarding peptide structural changes as a function of number of solvating water molecules are discussed. Not much is known at present about the effect of individual water molecules on the conformation of peptides and on the stability of peptide zwitterions.

  12. Modulation of the voltage-gated sodium- and calcium-dependent potassium channels in rat vestibular and facial nuclei after unilateral labyrinthectomy and facial nerve transsection: an in situ hybridization study

    Microsoft Academic Search

    T. Patk; I. Vassias; P. P. Vidal; C. De Waele

    2003-01-01

    We investigated whether the expression in the vestibular and facial nuclei of the voltage-dependent Na ?I and Na ?III channels and of the Ca2+-activated K+-channel subunits, small-conductance (SK) 1, SK2 and SK3, is affected by unilateral inner-ear lesion including both labyrinthectomy and transsection of the facial nerve. Specific sodium (Na ?I, Na ?III) and potassium (SK1, SK2, SK3) radioactive oligonucleotides

  13. Mallik Gas Hydrates Test Well

    USGS Multimedia Gallery

    A test-well for collecting gas hydrates in Mallik, Canada. Gas hydrates are naturally-occurring “ice-like” combinations of natural gas and water that have the potential to provide an immense resource of natural gas from the world’s oceans and polar regions....

  14. Bubble migration during hydrate formation

    NASA Astrophysics Data System (ADS)

    Shagapov, V. Sh.; Chiglintseva, A. S.; Rusinov, A. A.

    2015-03-01

    A model of the process of migration of methane bubbles in water under thermobaric conditions of hydrate formation is proposed. The peculiarities of the temperature field evolution, migration rate, and changes in the radius and volume fraction of gas hydrate bubbles are studied. It is shown that, with a constant mass flow of gas from the reservoir bottom, for all parameters of the surfacing gas hydrate disperse system, there is a quasistationary pattern in the form of a "step"-like wave. Depending on the relationship of the initial gas bubble density with the average gas density in the hydrate composition determined by the depth from which bubbles rise to the surface, the final radius of hydrate particles may be larger or smaller than the initial gas bubble radii. It is established that the speed at which gas hydrate inclusions rise to the surface decreases by several times due to an increase in their weight during hydrate formation. The influence of the depth of the water reservoir whose bottom is a gas flow source on the dynamics of hydrate formation is studied.

  15. Characterisation of ice and THF hydrate slurry crystal size distribution by microscopic observation method

    Microsoft Academic Search

    Anthony Delahaye; Laurence Fournaison; Jacques Guilpart

    2010-01-01

    The objective of the present work is to characterise, using an experimental microscopic observation device, the crystal size distribution (CSD) of ice and tetrahydrofuran (THF) hydrate slurries, which can be used as two-phase refrigerant fluids for cold transportation and storage in the field of secondary refrigeration. Three different solutes (ethanol, propylene glycol and sodium chloride) were used to form ice

  16. Gas Hydrate Petroleum System Analysis

    NASA Astrophysics Data System (ADS)

    Collett, T. S.

    2012-12-01

    In a gas hydrate petroleum system, the individual factors that contribute to the formation of gas hydrate accumulations, such as (1) gas hydrate pressure-temperature stability conditions, (2) gas source, (3) gas migration, and (4) the growth of the gas hydrate in suitable host sediment can identified and quantified. The study of know and inferred gas hydrate accumulations reveal the occurrence of concentrated gas hydrate is mostly controlled by the presence of fractures and/or coarser grained sediments. Field studies have concluded that hydrate grows preferentially in coarse-grained sediments because lower capillary pressures in these sediments permit the migration of gas and nucleation of hydrate. Due to the relatively distal nature of the deep marine geologic settings, the overall abundance of sand within the shallow geologic section is usually low. However, drilling projects in the offshore of Japan, Korea, and in the Gulf of Mexico has revealed the occurrence of significant hydrate-bearing sand reservoirs. The 1999/2000 Japan Nankai Trough drilling confirmed occurrence of hydrate-bearing sand-rich intervals (interpreted as turbidite fan deposits). Gas hydrate was determined to fill the pore spaces in these deposits, reaching saturations up to 80% in some layers. A multi-well drilling program titled "METI Toaki-oki to Kumano-nada" also identified sand-rich reservoirs with pore-filling hydrate. The recovered hydrate-bearing sand layers were described as very-fine- to fine-grained turbidite sand layers measuring from several centimeters up to a meter thick. However, the gross thickness of the hydrate-bearing sand layers were up to 50 m. In 2010, the Republic of Korea conducted the Second Ulleung Basin Gas Hydrate (UBGH2) Drilling Expedition. Seismic data clearly showed the development of a thick, potential basin wide, sedimentary sections characterized by mostly debris flows. The downhole LWD logs and core data from Site UBGH2-5 reveal that each debris flows is characterized by basal silt- to sand-rich clay dominated stratigraphic units. The upper most debris flow at Site UBGH2-5 extends into the overlying gas hydrate stability zone and IR core scans indicate that this section contains some amount of gas hydrate. The UBGH2 LWD and coring program also confirmed the occurrence of numerous volcaniclastic and siliciclastic sand reservoirs that were deposited as part of local to basin-wide turbidite events. Gas hydrate saturations within the turbidite sands ranged between 60-80 percent. In 2009, the Gulf of Mexico (GOM) Joint Industry Project (JIP) drilled seven wells at three sites, finding gas hydrate at high concentration in sands in four wells, with suspected gas hydrate at low to moderate saturations in two other wells. In the northern GOM, high sedimentation rates in conjunction with salt tectonism, has promoted the formation of complex seafloor topography. As a result, coarse-grained deposition can occur as gravity-driven sedimentation traversing the slope within intra-slope "ponded" accommodation spaces.

  17. The geochemical evolution of aqueous sodium in the Black Creek Aquifer, Horry and Georgetown counties, South Carolina

    USGS Publications Warehouse

    Zack, Allen L.; Roberts, Ivan

    1988-01-01

    The Black Creek aquifer contains dilute seawater near the North Carolina State line, probably the result of incomplete flushing of ancient seawater. Data do not indicate that the dilute seawater has migrated toward areas of fresh ground-water withdrawals. The concentration of chloride in ground-water samples ranges from 5 to 720 milligrams per liter and that of sodium from 160 to 690 milligrams per liter. Ion-exchange reactions (sodium for calcium and fluoride for hydroxyl) occur with the calcium carbonate dissolution reaction which produces calcium, bicarbonate, and hydroxyl ions. The reaction sequence and stoichiometry result in an aqueous solution in which the sum of bicarbonate and chloride equivalents per liter is equal to the equivalents per liter of sodium. Calcium ions are exchanged for sodium ions derived from sodium-rich clays upgradient of the dilute seawater. The cation-exchange reaction equilibrates at a sodium concentration of 280 milligrams per liter. Amounts of sodium greater than 280 milligrams per liter are contributed from dilute seawater. The cation-exchange reaction approaches an equilibrium which represents a mass-action limit in terms of the ratio of sodium to calcium in solution versus the ratio of exchangeable sodium to calcium on clay surfaces. Where the limit of calcium carbonate solubility is approached and dissolution ceases, some precipitation of calcite probably takes place. The dissolution of calcite exposes fossil shark teeth which release fluoride ions to the ground water through anion exchange with aqueous hydroxyl ions.

  18. Herbal extracts of Tribulus terrestris and Bergenia ligulata inhibit growth of calcium oxalate monohydrate crystals in vitro

    NASA Astrophysics Data System (ADS)

    Joshi, V. S.; Parekh, B. B.; Joshi, M. J.; Vaidya, A. B.

    2005-02-01

    A large number of people in this world are suffering from urinary stone problem. Calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) containing stones (calculi) are commonly found. In the present study, COM crystals were grown by a double diffusion gel growth technique using U-tubes. The gel was prepared from hydrated sodium metasilicate solution. The gel framework acts like a three-dimensional crucible in which the crystal nuclei are delicately held in the position of their formation, and nutrients are supplied for the growth. This technique can be utilized as a simplified screening static model to study the growth, inhibition and dissolution of urinary stones in vitro. The action of putative litholytic medicinal plants, Tribulus terrestris Linn. ( T.t) and Bergenia ligulata Linn. ( B.l.), has been studied in the growth of COM crystals. Tribulus terrestris and Bergenia ligulata are commonly used as herbal medicines for urinary calculi in India. To verify the inhibitive effect, aqueous extracts of Tribulus terrestris and Bergenia ligulata were added along with the supernatant solutions. The growth was measured and compared, with and without the aqueous extracts. Inhibition of COM crystal growth was observed in the herbal extracts. Maximum inhibition was observed in Bergenia ligulata followed by Tribulus terrestris. The results are discussed.

  19. Calcium and Vitamin D

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium is required for the bone formation phase of bone remodeling. Typically about 5 nmol (200 mg) of calcium is removed from the adult skeleton and replaced each day. To supply this amount, one would need to consume about 600 mg of calcium, since calcium is not very efficiently absorbed. Calcium ...

  20. Molecular simulation study of hydrated Na-rectorite.

    PubMed

    Zhou, Jinhong; Boek, Edo S; Zhu, Jianxi; Lu, Xiancai; Sprik, Michiel; He, Hongping

    2015-02-17

    The swelling behavior of clay minerals is an important issue in industrial processes and environmental applications. Mixed-layer clay minerals containing a smectite fraction, such as rectorite, are neglected even though they could swell and exist in nature widely. The hydration of rectorite has not been well comprehended even though they are meaningful to mineralogy and industry. This study combines molecular dynamics (MD) and Monte Carlo (MC) simulations to disclose the swelling behavior of rectorite and compare with montmorillonite. From grand canonical Monte Carlo (GCMC) and MD simulations, we obtain swelling curves and swelling free-energy curves of rectorite with a relative humidity of 100%. With the comparisons of swelling free-energy minima, we find that the bilayer hydrate of Na-rectorite is more thermodynamically stable than the monolayer hydrate, which is similar to Na-montmorillonite. However, the interlayer sodium ions in rectorite show an asymmetrical distribution quite different from the symmetrical distribution in montmorillonite. Because of unequal layer charges between the smectite part and illite part of retorite, sodium ions prefer to distribute close to the illite part surface. PMID:25625308

  1. Calcium entry via connexin hemichannels in lens epithelium.

    PubMed

    Mandal, Amritlal; Shahidullah, Mohammad; Delamere, Nicholas A

    2015-03-01

    Exposure to hyposmotic solution causes release of ATP from lens cells via hemichannels. Because hemichannel opening feasibly could swamp the cells with calcium, we carried out studies to measure the magnitude of the increase in cytoplasmic calcium concentration caused by hemichannel opening. In studies on porcine lens epithelial cells in primary culture, propidium iodide (PI) uptake was measured as an index of hemichannel opening. PI uptake was increased significantly in cells exposed to hyposmotic solution. The PI increase under hyposmotic conditions was suppressed by GAP 27, a connexin inhibitor peptide. In studies on cells loaded with Fura-2, continuous exposure to hyposmotic solution caused a cytoplasmic calcium concentration increase that peaked within ?30 s then remained elevated at or below the peak response for more than 60 min. The peak calcium concentration was 186 ± 2.3 nM compared to a baseline value of 98.0 ± 1.4 nM. The calcium concentration increased a lot further in cells exposed to A23187 (2.5 ?M) or the sodium-calcium exchange inhibitor SN-6 (10 ?M) added after the onset of the calcium rise in hyposmotic solution. The cytoplasmic calcium increase in hyposmotic solution was abolished by GAP 27. Calcium returned to baseline in cells exposed to hyposmotic solution then treated with GAP 27 starting 2 min after the onset of the calcium rise. The calcium increase in hyposmotic solution did not occur when calcium was eliminated from the bathing medium. The responses to hyposmotic and hyperosmotic stress were different. There was no detectable increase in calcium or PI entry in cells exposed to hyperosmotic solution (500mOsm). In summary, GAP 27-sensitive accumulation of PI by cultured lens epithelium points to connexin hemichannel opening and associated calcium entry. Even though connexins form channels with a large carrying capacity, calcium entry does not increase the cytoplasmic calcium concentration beyond a tolerable physiological range. PMID:25597520

  2. Get Enough Calcium

    MedlinePLUS

    ... Physical Activity > Nutrition > Get Enough Calcium Get Enough Calcium The Basics Take Action! Ver en español Content ... June 26, 2015 The Basics Your body needs calcium to build strong bones when you are young ...

  3. Calcium and bones (image)

    MedlinePLUS

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  4. Coronary Calcium Scan

    MedlinePLUS

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  5. In Situ Raman Analyses of Natural Gas and Gas Hydrates at Hydrate Ridge, Oregon

    Microsoft Academic Search

    E. T. Peltzer; S. N. White; R. M. Dunk; P. G. Brewer; A. D. Sherman; K. Schmidt; K. C. Hester; E. D. Sloan

    2004-01-01

    During a July 2004 cruise to Hydrate Ridge, Oregon, MBARI's sea-going laser Raman spectrometer was used to obtain in situ Raman spectra of natural gas hydrates and natural gas venting from the seafloor. This was the first in situ analysis of gas hydrates on the seafloor. The hydrate spectra were compared to laboratory analyses performed at the Center for Hydrate

  6. Calcium precursors for the production of CaO sorbents for multicycle CO2 capture.

    PubMed

    Liu, Wenqiang; Low, Nathanael W L; Feng, Bo; Wang, Guoxiong; Diniz da Costa, João C

    2010-01-15

    A screening of potential calcium precursors for the production of CaO sorbents for CO(2) capture at high temperature was conducted in this work. The precursors studied include microsized calcium carbonate (CC-CaO), calcium hydroxide (CH-CaO), nanosized (<70 nm) calcium carbonate (CC70 nm-CaO), nanosized (<160 nm) calcium oxide (CaO160 nm-CaO), calcium acetate hydrate (CA-CaO), calcium l-lactate hydrate (CL-CaO), calcium formate (CF-CaO), calcium citrate tetrahydrate (CCi-CaO), and calcium d-gluconate monohydrate (CG-CaO). The capture capability of these sorbents was investigated using a thermogravimetric analyzer (TGA) for multiple capture cycles. CG-CaO exhibited the best capacity for capturing CO(2) with a 1-min conversion of 65.9% and a 30-min conversion of 83.8% at the ninth cycle. Subsequently, a further parametric study was conducted to examine the effect of reaction conditions such as reaction temperature (550-750 degrees C) and CO(2) gas concentration (1-15%) on the capture capacity of CG-CaO. The sorbent CG-CaO also showed a much lower decomposition temperature and higher predicted residual conversion after prolonged cycles, compared with CC-CaO. PMID:20030311

  7. Water, Hydration and Health

    PubMed Central

    Popkin, Barry M.; D’Anci, Kristen E.; Rosenberg, Irwin H.

    2010-01-01

    This review attempts to provide some sense of our current knowledge of water including overall patterns of intake and some factors linked with intake, the complex mechanisms behind water homeostasis, the effects of variation in water intake on health and energy intake, weight, and human performance and functioning. Water represents a critical nutrient whose absence will be lethal within days. Water’s importance for prevention of nutrition-related noncommunicable diseases has emerged more recently because of the shift toward large proportions of fluids coming from caloric beverages. Nevertheless, there are major gaps in knowledge related to measurement of total fluid intake, hydration status at the population level, and few longer-term systematic interventions and no published random-controlled longer-term trials. We suggest some ways to examine water requirements as a means to encouraging more dialogue on this important topic. PMID:20646222

  8. Hydrates represent gas source, drilling hazard

    SciTech Connect

    Bagirov, E. [Azerbaijan Academy of Sciences, Baku (Azerbaijan); Lerche, I. [Univ. of South Carolina, Columbia, SC (United States)

    1997-12-01

    Gas hydrates look like ordinary ice. However, if a piece of such ice is put into warm water its behavior will be different from the ordinary melting of normal ice. In contrast, gas hydrates cause bubbles in the warm water, which indicates the high content of gas in the hydrate crystals. The presence of four components is required: gas itself, water, high pressure, and low temperature. The paper discusses how hydrates form, hydrates stability, South Caspian hydrates, and hydrates hazards for people, ships, pipelines, and drilling platforms.

  9. Dynamics of Protein Hydration Water

    E-print Network

    M. Wolf; S. Emmert; R. Gulich; P. Lunkenheimer; A. Loidl

    2014-12-08

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range including the so-called No Man's Land (160 - 235 K). The obtained results prove the bimodality of the hydration shell dynamics and are discussed in the context of the highly-debated fragile-to-strong transition of water.

  10. Gas Hydrates: It's a Gas

    NSDL National Science Digital Library

    In this activity, students will discover the importance of carbon, where carbon is stored on Earth, and that the largest reservoir of carbon is in the form of gas hydrates where methane and other hydrocarbon gases are trapped in a lattice of water molecules in deep sea sediments. Students will learn how climate change is related to the greenhouse effect. They will also learn about the potential of hydrates as a major new energy resource, and explore the conditions under which hydrates form. In addition, students will understand the use of acoustics for mapping the sea floor and sub-sea floor.

  11. Doped with Sodium Acetate and Metallic Sodium

    NASA Astrophysics Data System (ADS)

    Tada, Satoki; Isoda, Yukihiro; Udono, Haruhiko; Fujiu, Hirofumi; Kumagai, Shunji; Shinohara, Yoshikazu

    2014-06-01

    We have investigated the thermoelectric properties of p-type Na-doped Mg2 Si0.25Sn0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na was introduced into Mg2Si0.25Sn0.75 by using either sodium acetate (CH3COONa) or metallic sodium (2 N). The samples doped with sodium acetate consisted of phases with antifluorite structure and a small amount of MgO as revealed by x-ray diffraction, whereas the sample doped with metallic sodium contained the Sn, MgO, and Mg2SiSn phases. The hole concentrations of Mg1.975Na0.025Si0.25Sn0.75 doped by sodium acetate and metallic sodium were 1.84 × 1025 m-3 and 1.22 × 1025 m-3, respectively, resulting in resistivities of 4.96 × 10-5 ? m (sodium acetate) and 1.09 × 10-5 ? m (metallic sodium). The Seebeck coefficients were 198 ?V K-1 (sodium acetate) and 241 ?V K-1 (metallic sodium). The figures of merit for Mg1.975Na0.025Si0.25Sn0.75 were 0.40 × 10-3 K-1 (sodium acetate) and 0.25 × 10-3 K-1 (metallic sodium) at 400 K. Thus, sodium acetate is a suitable Na dopant for Mg2Si1- x Sn x .

  12. Obsidian hydration dates glacial loading?

    USGS Publications Warehouse

    Friedman, I.; Pierce, K.L.; Obradovich, J.D.; Long, W.D.

    1973-01-01

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming . The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  13. Obsidian hydration dates glacial loading?

    PubMed

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow. PMID:17806883

  14. Obsidian Hydration: A New Paleothermometer

    SciTech Connect

    Anovitz, Lawrence {Larry} M [ORNL; Riciputi, Lee R [ORNL; Cole, David R [ORNL; Fayek, Mostafa [ORNL; Elam, J. Michael [University of Tennessee, Knoxville (UTK)

    2006-01-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  15. Hydration kinetics of cement composites with varying water-cement ratio using terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Ray, Shaumik; Dash, Jyotirmayee; Devi, Nirmala; Sasmal, Saptarshi; Pesala, Bala

    2015-03-01

    Cement is mixed with water in an optimum ratio to form concrete with desirable mechanical strength and durability. The ability to track the consumption of major cement constituents, viz., Tri- and Dicalcium Silicates (C3S, C2S) reacting with water along with the formation of key hydration products, viz., Calcium-Silicate-Hydrate (C-S-H) which gives the overall strength to the concrete and Calcium Hydroxide (Ca(OH)2), a hydration product which reduces the strength and durability, using an efficient technique is highly desirable. Optimizing the amount of water to be mixed with cement is one of the main parameters which determine the strength of concrete. In this work, THz spectroscopy has been employed to track the variation in hydration kinetics for concrete samples with different water-cement ratios, viz., 0.3, 0.4, 0.5 and 0.6. Results show that for the sample with water-cement ratio of 0.3, significant amount of the C3S and C2S remain unreacted even after the initial hydration period of 28 days while for the cement with water-cement ratio of 0.6, most of the constituents get consumed during this stage. Analysis of the formation of Ca(OH)2 has been done which shows that the concrete sample with water-cement ratio of 0.6 produces the highest amount of Ca(OH)2 due to higher consumption of C3S/C2S in presence of excess water which is not desirable. Samples with water-cement ratio of 0.4 and 0.5 show more controlled reaction during the hydration which can imply formation of an optimized level of desired hydration products resulting in a more mechanically strong and durable concrete.

  16. Hydration and Temperature in Tennis - A Practical Review

    PubMed Central

    Kovacs, Mark S.

    2006-01-01

    Competitive tennis is typically played in warm and hot environments. Because hypohydration will impair tennis performance and increases the risk of heat injury, consumption of appropriate fluid levels is necessary to prevent dehydration and enhance performance. The majority of research in this area has focused on continuous aerobic activity - unlike tennis, which has average points lasting less than ten seconds with rest periods dispersed between each work period. For this reason, hydration and temperature regulation methods need to be specific to the activity. Tennis players can sweat more than 2.5 L·h-1 and replace fluids at a slower rate during matches than in practice. Latter stages of matches and tournaments are when tennis players are more susceptible to temperature and hydration related problems. Sodium (Na+) depletion, not potassium (K+), is a key electrolyte in tennis related muscle cramps. However, psychological and competitive factors also contribute. CHO drinks have been shown to promote fluid absorption to a greater degree than water alone, but no performance benefits have been shown in tennis players in short matches. It is advisable to consume a CHO beverage if practice or matches are scheduled longer than 90-120 minutes. Key Points Although substantial research has been performed on temperature and hydration concerns in aerobic activities, there is little information with regard to tennis performance and safety Tennis athletes should be on an individualized hydration schedule, consuming greater than 200ml of fluid every changeover (approximately 15 minutes). Optimum hydration and temperature regulation will reduce the chance of tennis related muscle cramps and performance decrements. PMID:24198676

  17. Hydrate control in deepwater drilling

    SciTech Connect

    NONE

    1997-09-01

    Gas-hydrate formation during deepwater offshore drilling and production is a well-recognized operational hazard. In water depths greater than 1,000 ft, seabed conditions of pressure and temperature become conducive to gas-hydrate formation. In a well-control situation, although the kick fluid leaves the formation at a high temperature, it can cool to seabed temperature with an extended shut-in period. With high enough hydrostatic pressure at the mudline, hydrates could form in the blowout-preventer (BOP) stack and choke and kill lines, as has been observed in field operations. The current practice in deepwater drilling is to suppress the hydrate-formation temperature by use of highly saline drilling fluids formulated from NaCl or other salts. This solution is applicable for the Gulf of Mexico but insufficient for the conditions encountered in Norwegian deep waters. At extreme water depths or extremely low mudline temperatures, this thermodynamic inhibition alone may not be sufficient to prevent hydrate formation. Instead, the use of kinetic inhibitors or crystal modifiers, in conjunction with thermodynamic inhibitors, may allow successful operations in such an environment. The definition of kinetic inhibitors (to distinguish them from the classic thermodynamic inhibitors, such as polar compounds and electrolytes) comes from the effect of the chemicals on the nucleation and growth of natural gas hydrates, both of which are time-dependent, stochastic processes. The paper describes deepwater drilling fluids, polar and surface-active additives, kinetic inhibition and crystal modifiers, laboratory measurements, and test results.

  18. Evolution of iron speciation during hydration of C{sub 4}AF

    SciTech Connect

    Rose, J. [CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France) and ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France)]. E-mail: rose@cerege.fr; Benard, A. [ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); INERIS, Domaine du Petit Arbois, BP 33, 13545 Aix en Provence (France); El Mrabet, S. [CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); Masion, A. [CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); Moulin, I. [LERM, 10, rue Mercoeur, 75011 Paris (France); Briois, V. [LURE Laboratoire pour l'Utilisation du Rayonnement Electromagnetique, Universite Paris-Sud, Orsay, France European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); Olivi, L. [ELETTRA Sincrotrone Trieste S.c.p.A. S. S. 14, Km. 163.5 in AREA Science Park, I-34012 Basovizza, TS (Italy); Bottero, J.-Y. [CEREGE Equipe physico-chimie des interfaces, UMR 6635 CNRS/Universite Paul Cezanne Aix-MarseilleIII-IFRE PSME 112, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France); ARDEVIE, Europole Mediterraneen de l'Arbois, BP 80, 13545 Aix en Provence Cedex 4 (France)

    2006-07-01

    It is now well accepted and demonstrated that calcium silicate, calcium aluminate and calcium sulfo aluminate (ettringite, AFm) phases exhibit a good capability to fix metals and metalloids. Unfortunately the role of minor phases and especially calcium-ferric aluminate phase, shorthand C{sub 4}AF is not well defined. In other systems like in soils or sediments iron phases play a key role in the fixation of pollutant. In cement sorption isotherms, indicated that various metals can be retained by the C{sub 4}AF hydrated products. Therefore the capabilities of those phase to retain heavy metal should not be neglected. Previous investigations have shown that the minerals formed during the hydration of C{sub 4}AF are similar to those formed from C3A (pure tri-calcium aluminate) under comparable conditions. Nevertheless no investigation was conducted at the molecular level and there is still a controversy whether Fe substitutes for Al in the hydrated minerals in whole or in part, or if it forms FeOOH clusters scattered throughout the matrix. In this context we have conducted XAS experiments using synchrotron radiation. It was found that the hydration of C{sub 4}AF forms C{sub 3}AH{sub 6} (hydrogarnet) in which Fe randomly substitutes for Al as well as an amorphous FeOOH phase. Intermediate products like AFm (i.e., an ill organized lamellar phase) are also formed but rapidly evolve to C{sub 3}AH{sub 6}; iron does not seem to be incorporated in the AFm structure.

  19. Carbonation Behavior of Pure Cement Hydrates under Supercritical Carbon Dioxide Conditions - 12199

    SciTech Connect

    Hirabayashi, Daisuke; Enokida, Youichi [Graduate School of Engineering, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya-shi, Aichi-ken, 464-8603 (Japan); Sawada, Kayo [EcoTopia Science Institute, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya-shi, Aichi-ken, 464-8603 (Japan); Hertz, Audrey; Charton, Frederic [CEA, DEN, Marcoule, DTCD/SPDE/L2ED, BP 17171, F-30207 Bagnols-sur-Ceze (France); Frizon, Fabien [CEA, DEN, Marcoule, DTCD/SPDE/LFSM, BP 17171, F-30207 Bagnols-sur-Ceze (France); Brouno, Fournel [CEA, DEN, Marcoule, DTCD, BP 17171, F-30207 Bagnols-sur-Ceze (France)

    2012-07-01

    Carbonation of cement-based waste forms using a supercritical carbon dioxide (SCCO{sub 2}) is a developing technology for the waste immobilization of radioactive and non-radioactive wastes. However, the detail carbonation behaviors of cement matrices under the SCCO{sub 2} condition are unknown, since cement matrices forms very complex phases. In this study, in order to clarify the crystal phases, we synthesized pure cement hydrate phases as each single phases; portlandite (Ca(OH){sub 2}), ettringite (Ca{sub 6}Al{sub 2}(SO{sub 4}){sub 3}(OH){sub 12}.26H{sub 2}O), and calcium silicate hydrate (n CaO---m SiO{sub 2} ---x H{sub 2}O), using suspensions containing a stoichiometric mixture of chemical regents, and performed carbonation experiments using an autoclave under supercritical condition for carbon dioxide. The XRD results revealed both the carbonate phases and co-product phases depending on the initial hydrate phases; gypsum for Ettringite, amorphous or crystalline silica for calcium silicate hydroxide. Thermogravimetric analysis was also performed to understand carbonation behaviors quantitatively. According to the experimental results, it was found that the major reaction was formation of calcium carbonate (CaCO{sub 3}) in all cases. However, the behaviors of H{sub 2}O and CO{sub 2} content were quietly different: Portlandite was most reactive for carbonation under SCCO{sub 2} conditions, and the CO{sub 2} content per one molar CaO was ranged from 0.96 ? 0.98. In the case of Ettringite, the experiment indicates partial decomposition of ettringite phase during carbonation. Ettringite was comparatively stable even under the SCCO{sub 2} conditions. Therefore, a part of ettringite remained and formed similar phases after the ettringite carbonation. The CO{sub 2} content for ettringite showed almost constant values around 0.86 ? 0.87. In the case of calcium silicate hydrate, the carbonation behavior was significantly influenced by the condition of SCCO{sub 2}. The CO{sub 2} content for the calcium silicate hydrate had values that ranged from 0.51 ? 1.01. The co-products of the carbonation were gypsum (CaSO{sub 4}) for ettringite, silica gel (SiO{sub x}) and silica (SiO{sub 2}) for calcium silicate hydrate, which also contributed to the densification of the particles. The production of co-products enhanced the change to their morphology after the carbonation. (authors)

  20. Transport Properties of Sodium Silicate Glasses with High Water Contents

    NASA Astrophysics Data System (ADS)

    Molinelli, Joyce E.

    Sodium disilicate and sodium tetrasilicate glasses with water contents ranging up to approximately eleven weight percent water were prepared by a hydrothermal method. They contain water as hydroxyls bonded to the silica network and molecular water located within the glass structure in non-network sites. Conduction and diffusion measurements were performed on these glasses to see the effects of the sample compositions on such properties as ionic conductivity, dielectric relaxation and sodium diffusion. Water hydration measurements were performed on sodium trisilicate glasses as well. It was found that ionic conductivity is due mainly to the motion of sodium ions. The conductivity, static dielectric constant, and sodium diffusion coefficient go through a minimum with increasing water content. This is attributed to the predominance of each of the two "types" of water in a part of the range of water contents studied. For any given water content, the conductivity and diffusion coefficient increase with increasing sodium oxide content. From the water hydration measurements, the diffusion coefficient of molecular water in the glass was estimated and was found to increase with increasing water content in the glasses studied. The hydration was found to be controlled by either of two mechanisms, the usual Fickian diffusion of molecular water due to the chemical potential gradient or Case II diffusion due to the stress gradient. Most compositions studied were predominantly controlled by one of these types, although there are expected to be compositions in which both types contribute significantly. It is believed that the hydroxyl content prevents ionic motion in these glasses. On the other hand, it is believed that the molecular water content contributes to the motion by a general loosening of the network, increasng conductivity and diffusion.

  1. Optimal Intracellular Calcium Signaling

    Microsoft Academic Search

    J. W. Shuai; P. Jung

    2002-01-01

    In many cell types, calcium is released from internal stores through calcium release channels upon external stimulation (e.g., pressure or receptor binding). These channels are clustered with a typical cluster size of about 20 channels, generating stochastic calcium puffs. We find that the clustering of the release channels in small clusters increases the sensitivity of the calcium response, allowing for

  2. Europa's sodium atmosphere

    NASA Astrophysics Data System (ADS)

    Cassidy, T. A.; Johnson, R. E.; Leblanc, F.

    2007-08-01

    Jupiter's moon Europa is exposed to intense ion and electron flux that erodes the surface, launching atoms and molecules into ballistic trajectories to form a tenuous atmosphere (e.g., Johnson et al., "Jupiter," book, 2004). One component of that atmosphere is neutral atomic sodium, which has been observed many times by Earth-based telescopes (e.g., Leblanc et al., Icarus, 2005). When the Cassini spacecraft viewed Europa during an eclipse by Jupiter its visible camera revealed spatially nonuniform emission (Porco et al., Science, 2003, Supporting Online Material). The Cassini eclipse observations were performed with the Narrow Angle Camera (NAC) and clear filters (Porco et al., 2003). Clear filters provide sensitivity to the wavelength range 200-1050 nm, with maximum sensitivity at 611 nm (Porco et al., 2004). Within that wavelength range there are a number of lines that might contribute to the observed glow. These include the electron impact-induced excitation of Na (Kim, Phys. Rev. A, 2001), O (Fig. 4 Smyth and Marconi, Icarus, 2006), K, and SO2 (Ajello et al., J. Geophys. Res., 1992). Ions may also make a small contribution to these same processes (e.g., Allen et al., Phys. Rev. A, 1988). Of these, electron excitation of Na D line emission is likely the dominant emission in eclipse. Using an atmospheric model described by Cassidy et al. (2007), we successfully model those emissions by assuming that the Na atoms are ejected preferentially from Europa's trailing hemisphere dark terrain, which may be rich in Na-containing salt hydrates. We will discuss those results and, if available, discuss similar observations by the recent New Horizons Jupiter flyby.

  3. Chloride- and alkali-containing calcium phosphates as basic materials to prepare calcium phosphate cements.

    PubMed

    Bermúdez, O; Boltong, M G; Driessens, F C; Ginebra, M P; Fernández, E; Planell, J A

    1994-10-01

    Combinations of an alkali-containing calcium phosphate-like rhenanite, sodium whitlockite or calcium potassium phosphate and a chloride-containing calcium phosphate-like spodiosite or chloroapatite with or without additions of other calcium phosphates like monocalcium phosphate monohydrate, dicalcium phosphate or dicalcium phosphate dihydrate were made and mixed with water into pastes. The setting time of these pastes was determined. After soaking for a day in Ringer's solution at 37 degrees C the compressive strength and the diametral tensile strength were determined. Two of the combinations tried in this study resulted in the formation of cements at room temperature. One cement was of the type dicalcium phosphate, whereas the other gave octocalcium phosphate as the solid reaction product. The byproducts formed were an aqueous solution of NaCl and one of K2HPO4, respectively. Applications for bone repair and augmentation are envisaged. PMID:7841290

  4. Immobilization hypercalcaemia responding to intravenous pamidronate sodium therapy.

    PubMed Central

    McIntyre, H. D.; Cameron, D. P.; Urquhart, S. M.; Davies, W. E.

    1989-01-01

    A 16 year old male developed symptomatic hypercalcaemia of immobilization on day 47 following a diving accident which had resulted in incomplete C4 tetraplegia. Following initial reduction in serum calcium with salmon calcitonin 100 U/day, symptomatic hypercalcaemia recurred. A single dose of 30 mg pamidronate sodium, given intravenously, caused serum calcium to fall within 48 hours. Initial mild, asymptomatic hypocalcaemia was followed by a return to sustained normocalcaemia. No major adverse reaction was encountered, and if further clinical experience confirms its efficacy, pamidronate sodium will warrant consideration as first-line therapy for immobilization hypercalcaemia. PMID:2594602

  5. Update on Calcium Signaling Calcium Signaling through Protein Kinases. The

    E-print Network

    Sheen, Jen

    Update on Calcium Signaling Calcium Signaling through Protein Kinases. The Arabidopsis Calcium protein kinase activities occur through calcium-dependent protein kinases (CDPKs). These novel calcium provides a valuable opportunity to understand the plant calcium-signaling network. Calcium is a ubiquitous

  6. Effects of thyroid status on renal calcium and magnesium handling.

    PubMed Central

    McCaffrey, C; Quamme, G A

    1984-01-01

    Renal calcium and magnesium handling was studied in rats with chronic thyroid hormone deficiency or excess, hyperthyroidism. Mean kidney weight of the thyroid deficient rats was 42% of age matched, euthyroid and hyperthyroid animals and glomerular filtration rate was 71% of normal. Fractional sodium excretion was consistently elevated in thyroid deficient rats (0.26%) as compared to euthyroid (0.07%) and hyperthyroid animals (0.07%). Urinary calcium excretion (0.39%) was also elevated and parallel to sodium excretion in thyroid deficiency. Despite this renal leak of sodium and calcium, thyroid deficient animals conserved magnesium much more efficiently than either euthyroid or hyperthyroid rats (5.7% vs 17.4% respectively). Plasma magnesium concentration was elevated by acute MgCl2 infusions to determine the reabsorptive capacity of magnesium. Thyroid deficient rats reabsorbed 15-30% more of the filtered magnesium at any given plasma concentration. Although these effects on electrolyte reabsorption are modest compared to the hemodynamic alterations, the data suggest that thyroid hormone has a direct effect on the tubule which if chronically absent results in subtle sodium and calcium wasting and renal retention of magnesium. Administration of thyroid hormone to euthyroid or thyroid deficient rats twenty-four hours prior to experimentation had no effect on calcium and magnesium handling. PMID:6713257

  7. Morphology study of methane-propane clathrate hydrates on the bubble surface in the presence of SDS or PVCap

    NASA Astrophysics Data System (ADS)

    Lee, So Young; Kim, Hyoung Chan; Lee, Ju Dong

    2014-09-01

    The characteristics of methane-propane hydrate crystal growth on the surface of gas bubble in pure water were investigated using optical microscope and compared with those in aqueous solutions of sodium dodecyl sulfate (SDS) or poly-N-vinylcaprolactam (PVCap). Most of morphology works in literature mainly focused on the hydrate crystal growth at the gas/water interface or surface of water droplets. However, this study monitors crystal growth at the bubble surface. In the case of pure water, smooth hydrate film was formed initially and the film surface on the bubble became rough as experiment proceeded. It was also observed that the hydrate crystals developed as the dendritic shape from the surface of hydrate film. In the presence of SDS, drastic changes in morphology were observed in that smoke-like crystals appeared from the top of the bubble. Besides, the gas bubble was not fully covered by hydrate film when the SDS concentration increased. In the PVCap solution, seed-like or small spot of hydrate crystals occurred sparsely on the bubble surface and spread out the whole surface as experiment progressed. The experimental results showed that the presence of SDS or PVCap affect morphological characteristics of methane-propane hydrate crystal on the surface of gas bubble.

  8. A realistic molecular model of cement hydrates

    PubMed Central

    Pellenq, Roland J.-M.; Kushima, Akihiro; Shahsavari, Rouzbeh; Van Vliet, Krystyn J.; Buehler, Markus J.; Yip, Sidney; Ulm, Franz-Josef

    2009-01-01

    Despite decades of studies of calcium-silicate-hydrate (C-S-H), the structurally complex binder phase of concrete, the interplay between chemical composition and density remains essentially unexplored. Together these characteristics of C-S-H define and modulate the physical and mechanical properties of this “liquid stone” gel phase. With the recent determination of the calcium/silicon (C/S = 1.7) ratio and the density of the C-S-H particle (2.6 g/cm3) by neutron scattering measurements, there is new urgency to the challenge of explaining these essential properties. Here we propose a molecular model of C-S-H based on a bottom-up atomistic simulation approach that considers only the chemical specificity of the system as the overriding constraint. By allowing for short silica chains distributed as monomers, dimers, and pentamers, this C-S-H archetype of a molecular description of interacting CaO, SiO2, and H2O units provides not only realistic values of the C/S ratio and the density computed by grand canonical Monte Carlo simulation of water adsorption at 300 K. The model, with a chemical composition of (CaO)1.65(SiO2)(H2O)1.75, also predicts other essential structural features and fundamental physical properties amenable to experimental validation, which suggest that the C-S-H gel structure includes both glass-like short-range order and crystalline features of the mineral tobermorite. Additionally, we probe the mechanical stiffness, strength, and hydrolytic shear response of our molecular model, as compared to experimentally measured properties of C-S-H. The latter results illustrate the prospect of treating cement on equal footing with metals and ceramics in the current application of mechanism-based models and multiscale simulations to study inelastic deformation and cracking. PMID:19805265

  9. Sodium in diet

    MedlinePLUS

    Diet - sodium (salt) ... salt is 40% sodium; 1 teaspoon of table salt contains 2,300 mg of sodium. Healthy adults should limit sodium intake to 2,300 mg per day. Adults with high blood pressure should have no more than 1,500 mg ...

  10. Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

    NASA Technical Reports Server (NTRS)

    Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

  11. Calcium and nitrogen balance, experiment M007

    NASA Technical Reports Server (NTRS)

    Whedon, G. D.; Lutwak, L.; Neuman, W. F.; Lachance, P. A.

    1971-01-01

    The collection of data on the response of the skeletal and muscular systems to 14-day space flights was evaluated for loss of calcium, nitrogen, and other metabolically related elements. Considerable interindividual variability was demonstrated in all experimental factors that were measured. Calcium balance became less positive and urinary phosphate excretion increased substantially in flight despite a reduction in phosphate intake. Patterns of excretion of magnesium, sodium, potassium, and chloride were different for each subject, and, in part, could be correlated with changes in adrenocortical steroid production. The principal hormonal change was a striking decrease during flight in the urinary excretion of 17-hydroxycortocosteroids. Dermal losses of calcium, magnesium, sulfate, and phosphate were insignificant during all three phases.

  12. EFFECT OF QUARTZ/MULLITE BLEND CERAMIC ADDITIVE ON IMPROVING RESISTANCE TO ACID OF SODIUM SILICATE-ACTIVATED SLAG CEMENT. CELCIUS BRINE.

    SciTech Connect

    SUGAMA, T.; BROTHERS, L.E.; VAN DE PUTTE, T.R.

    2006-06-01

    We evaluated the usefulness of manufactured quartz/mullite blend (MQMB) ceramic powder in increasing the resistance to acid of sodium silicate-activated slag (SSAS) cementitious material for geothermal wells. A 15-day exposure to 90{sup o} CO{sub 2}-laden H{sub 2}SO{sub 4} revealed that the MQMB had high potential as an acid-resistant additive for SSAS cement. Two factors, the appropriate ratio of slag/MQMB and the autoclave temperature, contributed to better performance of MQMB-modified SSAS cement in abating its acid erosion. The most effective slag/MQMB ratio in minimizing the loss in weight by acid erosion was 70/30 by weight. For autoclave temperature, the loss in weight of 100 C autoclaved cement was a less than 2%, but at 300 C it was even lower. Before exposure to acid, the cement autoclaved at 100 C was essentially amorphous; increasing the temperature to 200 C led to the formation of crystalline analcime in the zeolitic mineral family during reactions between the mullite in MQMB and the Na from sodium silicate. In addition, at 300 C, crystal of calcium silicate hydrate (1) (CSH) was generated in reactions between the quartz in MQMB and the activated slag. These two crystalline phases (CSH and analcime) were responsible for densifying the autoclaved cement, conveying improved compressive strength and minimizing water permeability. The CSH was susceptible to reactions with H{sub 2}SO{sub 4}, forming two corrosion products, bassanite and ionized monosilicic acid. However, the uptake of ionized monosilicic acid by Mg dissociated from the activated slag resulted in the formation of lizardite as magnesium silicate hydrate. On the other hand, the analcime was barely susceptible to acid if at all. Thus, the excellent acid resistance of MQMB-modified SSAS cement was due to the combined phases of lizardite and analcime.

  13. Passing gas through the hydrate stability zone at southern Hydrate Ridge, offshore Oregon

    Microsoft Academic Search

    Xiaoli Liu; Peter B. Flemings

    2006-01-01

    We present an equilibrium model of methane venting through the hydrate stability zone at southern Hydrate Ridge, offshore Oregon. Free gas supplied from below forms hydrate, depletes water, and elevates salinity until pore water is too saline for further hydrate formation. This system self-generates local three-phase equilibrium and allows free gas migration to the seafloor. Log and core data from

  14. Polymorphs and hydrates of acyclovir.

    PubMed

    Lutker, Katie M; Quiñones, Rosalynn; Xu, Jiadi; Ramamoorthy, Ayyalusamy; Matzger, Adam J

    2011-03-01

    Acyclovir (ACV) has been commonly used as an antiviral for decades. Although the crystal structure of the commercial form, a 3:2 ACV/water solvate, has been known since 1980s, investigation into the structure of anhydrous ACV has been limited. Here, we report the characterization of four anhydrous forms of ACV and a new hydrate in addition to the known hydrate. Two of the anhydrous forms appear as small needles and are stable to air exposure, whereas the third form is morphologically similar but quickly absorbs water from the atmosphere and converts back to the commercial form. The high-temperature modification is achieved by heating anhydrous form I above 180 °C. The crystal structures of anhydrous form I and a novel hydrate are reported for the first time. PMID:21280051

  15. CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  16. SLAM: a sodium-limestone concrete ablation model

    SciTech Connect

    Suo-Anttila, A.J.

    1983-12-01

    SLAM is a three-region model, containing a pool (sodium and reaction debris) region, a dry (boundary layer and dehydrated concrete) region, and a wet (hydrated concrete) region. The model includes a solution to the mass, momentum, and energy equations in each region. A chemical kinetics model is included to provide heat sources due to chemical reactions between the sodium and the concrete. Both isolated model as well as integrated whole code evaluations have been made with good results. The chemical kinetics and water migration models were evaluated separately, with good results. Several small and large-scale sodium limestone concrete experiments were simulated with reasonable agreement between SLAM and the experimental results. The SLAM code was applied to investigate the effects of mixing, pool temperature, pool depth and fluidization. All these phenomena were found to be of significance in the predicted response of the sodium concrete interaction. Pool fluidization is predicted to be the most important variable in large scale interactions.

  17. Hydration of highly charged ions

    PubMed Central

    Hofer, Thomas S.; Weiss, Alexander K.H.; Randolf, Bernhard R.; Rode, Bernd M.

    2011-01-01

    Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of hydrates of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the hydrates appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results. PMID:22298911

  18. Gas Hydrate and Pore Pressure

    NASA Astrophysics Data System (ADS)

    Tinivella, Umberta; Giustiniani, Michela

    2014-05-01

    Many efforts have been devoted to quantify excess pore pressures related to gas hydrate dissociation in marine sediments below the BSR using several approaches. Dissociation of gas hydrates in proximity of the BSR, in response to a change in the physical environment (i.e., temperature and/or pressure regime), can liberate excess gas incrising the local pore fluid pressure in the sediment, so decreasing the effective normal stress. So, gas hydrate dissociation may lead to excess pore pressure resulting in sediment deformation or failure, such as submarine landslides, sediment slumping, pockmarks and mud volcanoes, soft-sediment deformation and giant hummocks. Moreover, excess pore pressure may be the result of gas hydrate dissociation due to continuous sedimentation, tectonic uplift, sea level fall, heating or inhibitor injection. In order to detect the presence of the overpressure below the BSR, we propose two approachs. The fist approach models the BSR depth versus pore pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas hydrate stability is deeper with respect to the hydrostatic case. This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas hydrate and free gas concentrations and pore pressure, considering the approximation of the Biot theory in case of low frequency, i.e. seismic frequency. Knowing the P and S seismic velocity from seismic data analysis, it is possibile to jointly estimate the gas hydrate and free gas concentrations and the pore pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson ratio. Our modeling suggests that the areas characterized by shallow waters (i.e., areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition. Moreover, the knoweledge of seismic velocities can be considered an powerful tool to detect the overpressure in case that the pore pressure is equal to the hydrostatic pressure plus the 50% of the difference between the lithostatic and the hydrostatic pressure. In conclusions, an accurate analysis of the BSR nature and the pore pressure are required to improve the reliability of the gas-phase estimation for different target, such as gas hydrate and free gas exploitations and environmental studies.

  19. Dehydration of plutonium trichloride hydrate

    SciTech Connect

    Foropoulos, J. Jr.; Avens, L.R.; Trujillo, E.A.

    1991-12-31

    A process of preparing anhydrous actinide metal trichlorides of plutonium or neptunium by reacting an aqueous solution of an actinide metal trichloride selected from the group consisting of plutonium trichloride or neptunium trichloride with a reducing agent capable of converting the actinide metal from an oxidation state of +4 to +3 in a resultant solution, evaporating essentially all the solvent from the resultant solution to yield an actinide trichloride hydrate material, dehydrating the actinide trichloride hydrate material by heating the material in admixture with excess thionyl chloride, and recovering anhydrous actinide trichloride is provided.

  20. Heat stability and calcium bioavailability of calcium-fortified milk

    Microsoft Academic Search

    G. Singh; S. Arora; G. S. Sharma; J. S. Sindhu; V. K. Kansal; R. B. Sangwan

    2007-01-01

    The objective of the study was to fortify calcium in cow milk in order to prepare calcium-enriched heat-stable milk for individuals who may not ingest enough calcium to meet minimum daily requirements. Therefore, cow milk was fortified with calcium at the rate of 50mg\\/100ml using three salts of calcium, viz. calcium chloride, calcium lactate and calcium gluconate. Upon addition of

  1. Aerosol mass spectrometric measurements of stable crystal hydrates of oxalates and inferred relative ionization efficiency of water

    Microsoft Academic Search

    A. A. Mensah; A. Buchholz; Th. F. Mentel; R. Tillmann; A. Kiendler-Scharr

    2011-01-01

    We investigated the crystal hydrates of ammonium oxalate, potassium oxalate and oxalic acid as well as sodium oxalate. By taking advantage of the different crystal water contents we determined for the first time the relative ionization efficiency of water (RIEH2O) in an Aerodyne Aerosol Mass Spectrometer (AMS). The RIE is a key parameter for the quantitative measurement of a compounds’

  2. Hydration properties of Na, K, Mg gluconates and gluconate\\/sucrose mixtures and their possible taste effect

    Microsoft Academic Search

    V Aroulmoji; M Mathlouthi; G. G Birch

    2000-01-01

    Density and ultrasonic velocity were measured in aqueous solutions of sodium, potassium and magnesium gluconate as a function of increasing concentration. Apparent molar volume (AMV), apparent specific volume (ASV), isentropic apparent molar (IAMC) compressibility and hydration numbers were calculated from the experimental data. The results show that AMV and ASV increase as the concentration of gluconates is increased. This is

  3. The effect of sodium bicarbonate ingestion on 1500?m racing time

    Microsoft Academic Search

    S. R. Bird; J. Wiles; J. Robbins

    1995-01-01

    Twelve athletes, all of whom regularly participated in middle? or long?distance running races at club to national standard, competed in simulated 1500?m races under three conditions: following ingestion of 300 mg sodium bicarbonate per kg of body mass (B); following ingestion of a placebo (100 mg sodium chloride per kg of body mass and 200 mg calcium carbonate per kg

  4. “Late sodium current: a mechanism for angina, heart failure, and arrhythmia”

    PubMed Central

    Makielski, Jonathan C.

    2015-01-01

    The peak sodium current underlies excitability and conduction in heart muscle, but a late sodium current flowing after the peak contributes to maintaining and prolonging the action potential plateau, and also to intracellular sodium loading, that in turn increases intracellular calcium with consequent effects on arrhythmia and diastolic function. Late sodium current is pathologically increased in both genetic and acquired heart disease, making it an attractive target for therapy to treat arrhythmia, heart failure, and angina. This review provides an overview of the underlying bases for the clinical implications of late sodium current block. PMID:19333133

  5. Caveolae and calcium handling, a review and a hypothesis

    PubMed Central

    Daniel, E E; El-Yazbi, A; Cho, W J

    2006-01-01

    Caveolae are associated with molecules crucial for calcium handling. This review considers the roles of caveolae in calcium handling for smooth muscle and interstitial cells of Cajal (ICC). Structural studies showed that the plasma membrane calcium pump (PMCA), a sodium-calcium exchanger (NCX1), and a myogenic nNOS appear to be colocalized with caveolin I, the main constituent of these caveolae. Voltage dependent calcium channels (VDCC) are associated but not co-localized with caveolin 1, as are proteins of the peripheral sarcoplasmic reticulum (SR) such as calreticulin. Only the nNOS is absent from caveolin 1 knockout animals. Functional studies in calcium free media sugest that a source of calcium in tonic smooth muscles exists, partly sequestered from extracellular EGTA. This source supported sustained contractions to carbachol using VDCC and dependent on activity of the SERCA pump. This source is postulated to be caveolae, near peripheral SR. New evidence, presented here, suggests that a similar source exists in phasic smooth muscle of the intestine and its ICC. These results suggest that caveolae and peripheral SR are a functional unit recycling calcium through VDCC and controlling its local concentration. Calcium handling molecules associated with caveolae in smooth muscle and ICC were identified and their possible functions also reviewed. PMID:16796818

  6. Gemini near-infrared observations of Europa's Hydrated Surface Materials

    NASA Astrophysics Data System (ADS)

    Tsang, C.; Spencer, J. R.; Grundy, W. M.; Dalton, J. B.

    2012-12-01

    Europa is a highly dynamic icy moon of Jupiter. It is thought the moon harbors a subsurface ocean, with the potential to sustain life, with Europa being a key target of ESA's forthcoming Jupiter Icy Moons Orbiter (JUICE) mission. However, much is not known concerning the chemistry of the subsurface ocean. The surface is dominated by water ice, with a hydrated non-ice material component providing the distinctive albedo contrasts seen at visible and near-infrared wavelengths. These non-ice materials are concentrated at disrupted surface regions, providing a diagnostic probe for the chemistry and characteristics of the liquid ocean beneath. Leading but potentially competing theories on the composition of these hydrated non-ice materials suggest either sulfuric acid-water mixtures (Carlson et al., 1999) or hydrated magnesium/sodium salts (McCord et al., 1999). Recent reanalysis of Galileo-NIMS observations suggest a mixture of both - hydrated salts are present at all longitudes but the sulfuric acid hydrates are localized on the trailing side. We present preliminary analysis of new ground-based Gemini disk-resolved spectroscopy of Europa using the Near-Infrared Integrated Field Spectrometer (NIFS), taken in late 2011, at H (1.49 - 1.80 ?m) and K bands (1.99 - 2.40 ?m) with spectral resolving powers of ~ 5300. At these NIR wavelengths, with spectral resolution much better than Galileo-NIMS, the spectral absorption and continuum characteristics of these ice and non-ice materials can be separated out. In addition, the spatial resolution potentially allows identification of localized materials whose signature would be diluted in disk-integrated spectra. These observations of the trailing hemisphere use Altair adaptive optics to achieve spatial resolutions of 0.1" (~310 km per pixel) or better, potentially leading to better identification of the non-ice materials and their spatial distributions. References Carlson, R.W., R.E. Johnson, and M.S. Anderson 1999. Sulfuric acid on Europa and the radiolytic sulfur cycle. Science 286, 97-99. McCord, T. et al. 1999. Hydrated salt minerals on Europa's surface from the Galileo Near- Infrared Mapping Spectrometer (NIMS) investigation. J. Geophys. Res. 104, 11827

  7. Calcium and Mitosis

    NASA Technical Reports Server (NTRS)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  8. Thermal properties of methane gas hydrates

    USGS Publications Warehouse

    Waite, William F.

    2007-01-01

    Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, ?: if ? is high, heat travels easily through the material. - Thermal diffusivity, ?: if ? is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to raise the temperature of the material.

  9. Effects of hydration with salt repletion on renal toxicity of conventional amphotericin B empirical therapy: a prospective study in patients with hematological malignancies

    Microsoft Academic Search

    Corrado Girmenia; Giuseppe Cimino; Francesca Cristofano; Alessandra Micozzi; Giuseppe Gentile; Pietro Martino

    2005-01-01

    Objective: Several studies have suggested that hydration and sodium load might reduce nephro- toxicity related to amphotericin B-deoxycholate (AmB-d). However, a schedule of these nephroprotective measures has not been standardized until now. A protocol of hydration and electrolyte supplementation was used prospectively in patients with hematological malignancies receiving empirical AmB-d treatment to evalu- ate its effect on AmB-d-related renal toxicity.

  10. RESEARCH ARTICLE CALCIUM CHANNEL STRUCTURE

    E-print Network

    Napp, Nils

    RESEARCH ARTICLE CALCIUM CHANNEL STRUCTURE Structural basis for a pH-sensitive calcium leak across,3 Wayne A. Hendrickson,1,2,4,5 Qun Liu1,4 * Calcium homeostasis balances passive calcium leak and active calcium uptake. Human Bax inhibitor­1 (hBI-1) is an antiapoptotic protein that mediates a calcium leak

  11. Calcium Secretion into Milk

    Microsoft Academic Search

    Margaret C. Neville

    2005-01-01

    Ionized calcium ([Ca2+]) is present in milk at concentrations around 3 mM, a concentration that drives the formation of complexes with citrate, phosphate, and casein, thereby generating compounds that carry the major portion of calcium in milk. In humans and cows, where it has been studied, changes in milk calcium appear to be regulated by the amount of citrate and

  12. Hydration rind dates rhyolite flows

    USGS Publications Warehouse

    Friedman, I.

    1968-01-01

    Hydration of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago.

  13. Hydration rind dates rhyolite flows.

    PubMed

    Friedman, I

    1968-02-23

    Hydration of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago. PMID:17768978

  14. Attraction between hydrated hydrophilic surfaces

    NASA Astrophysics Data System (ADS)

    Kandu?, Matej; Schneck, Emanuel; Netz, Roland R.

    2014-08-01

    According to common knowledge, hydrophilic surfaces repel via hydration forces while hydrophobic surfaces attract, but mounting experimental evidence suggests that also hydrophilic surfaces can attract. Using all-atom molecular dynamics simulations at prescribed water chemical potential we study the crossover from hydration repulsion to hydrophobic attraction for planar polar surfaces of varying stiffness and hydrogen-bonding capability. Rescaling the partial charges of the polar surface groups, we cover the complete spectrum from very hydrophobic surfaces (characterized by contact angles ? ? 135°) to hydrophilic surfaces exhibiting complete wetting (? = 0°). Indeed, for a finite range ?adh < ? < 90°, we find a regime where hydrophilic surfaces attract at sub-nanometer separation and stably adhere without intervening water. The adhesive contact angle ?adh depends on surface type and lies in the range 65° < ?adh < 80°, in good agreement with experiments. Analysis of the total number of hydrogen bonds (HBs) formed by water and surface groups rationalizes this crossover between hydration repulsion and hydrophilic attraction in terms of a subtle balance: Highly polar surfaces repel because of strongly bound hydration water, less polar hydrophilic surfaces attract because water-water HBs are preferred over surface-water HBs. Such solvent reorganization forces presumably underlie also other important phenomena, such as selective ion adsorption to interfaces as well as ion pair formation.

  15. SIMULTANEOUS CONTROL OF HGO, SO2, AND NOX BY NOVEL OXIDIZED CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of an investigation of two classes of calcium (Ca)-based sorbents (hydrated limes and silicate compounds). (NOTE: Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents...

  16. SIMULTANEOUS CONTROL OF HG(0), SO2, AND NOX BY NOVEL OXIDIZED CALCIUM-BASED SORBENTS

    EPA Science Inventory

    The paper gives results of an investigation of two classes of calcium (Ca)-based sorbents (hydrated limes and silicate compounds). {NOTE: Efforts to develop multipollutant control strategies have demonstrated that adding certain oxidants to different classes of Ca-based sorbents ...

  17. CO2 hydrate nucleation kinetics enhanced by an organo-mineral complex formed at the montmorillonite-water interface.

    PubMed

    Kyung, Daeseung; Lim, Hyung-Kyu; Kim, Hyungjun; Lee, Woojin

    2015-01-20

    In this study, we investigated experimentally and computationally the effect of organo-mineral complexes on the nucleation kinetics of CO2 hydrate. These complexes formed via adsorption of zwitter-ionic glycine (Gly-zw) onto the surface of sodium montmorillonite (Na-MMT). The electrostatic attraction between the ?NH3(+) group of Gly-zw, and the negatively charged Na-MMT surface, provides the thermodynamic driving force for the organo-mineral complexation. We suggest that the complexation of Gly-zw on the Na-MMT surface accelerates CO2 hydrate nucleation kinetics by increasing the mineral–water interfacial area (thus increasing the number of effective hydrate-nucleation sites), and also by suppressing the thermal fluctuation of solvated Na(+) (a well-known hydrate formation inhibitor) in the vicinity of the mineral surface by coordinating with the ?COO(–) groups of Gly-zw. We further confirmed that the local density of hydrate-forming molecules (i.e., reactants of CO2 and water) at the mineral surface (regardless of the presence of Gly-zw) becomes greater than that of bulk phase. This is expected to promote the hydrate nucleation kinetics at the surface. Our study sheds new light on CO2 hydrate nucleation kinetics in heterogeneous marine environments, and could provide knowledge fundamental to successful CO2 sequestration under seabed sediments. PMID:25532462

  18. Controlling nitrogen oxide and sulfur dioxide emissions with modified calcium hydroxide

    Microsoft Academic Search

    J. B. L. Harkness; R. D; W. I. Wilson

    1986-01-01

    Nitrogen oxides have been removed from simulated flue gases typical of coal firing by treating hydrated lime with a variety of additives. Benchscale experiments with a fixed-bed reactor were used to screen sodium hydroxide, sodium sulfite, aluminum sulfate, Fe(II) EDTA (complex of ferrous and ethylenediaminetetraacetic acid), and Al\\/CIT (a complex of aluminum and citric acid), and three other reagents of

  19. Sodium blood test

    MedlinePLUS

    ... of diuretics, or burns Too much salt or sodium bicarbonate in the diet Use of certain medicines, including birth control pills, corticosteroids, laxatives, lithium, and ... than normal sodium level is called hyponatremia. It may be due ...

  20. Sodium in Drinking Water

    MedlinePLUS

    ... To reduce my sodium intake, should I buy bottled water instead of using tap water? For more information. ... To reduce my sodium intake, should I buy bottled water instead of using tap water? It is not ...

  1. Sodium Polystyrene Sulfonate

    MedlinePLUS

    Sodium polystyrene sulfonate is used to treat increased amounts of potassium in the body. ... Sodium polystyrene sulfonate comes as a powder and suspension to take by mouth. It may also be used as a ...

  2. Diclofenac sodium overdose

    MedlinePLUS

    Diclofenac sodium is a prescription medicine used to relieve pain and swelling. It is a nonsteroidal anti-inflammatory drug (NSAID). Diclofenac sodium overdose occurs when someone accidentally or intentionally ...

  3. Handbook of gas hydrate properties and occurrence

    SciTech Connect

    Kuustraa, V.A.; Hammershaimb, E.C.

    1983-12-01

    This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

  4. Effect of dietary salt intake on circadian calcium metabolism, bone turnover, and calcium oxalate kidney stone risk in postmenopausal women

    Microsoft Academic Search

    Linda K. Massey

    2005-01-01

    Increasing dietary salt (sodium chloride) increases urinary calcium excretion, which may increase the risk of developing osteoporosis and kidney stones. Ten postmenopausal women without osteoporosis or kidney stones who were not undergoing hormone replacement therapy ate all meals in a metabolic unit for 14 days: 7 days at each salt level in a crossover design. The 2 diets differed only

  5. Thermal conductivity of hydrate-bearing sediments

    USGS Publications Warehouse

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

  6. Out-Of-Drum Grout Mixer Testing With Simulated Liquid Effluents Originating From Sodium-Bearing Waste at the Idaho Nuclear Technology and Engineering Center

    Microsoft Academic Search

    B. A. Scholes; A. K. Herbst; S. V. Raman; S. H. Hinckley

    2003-01-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is considering several optional processes for disposal of liquid sodium-bearing waste. During fiscal year 2003, alternatives were evaluated for grout formulation development and associated mixing for the Sodium-Bearing Waste cesium ion exchange process. The neutralization agents calcium or sodium hydroxide and the solidification agents Portland cement, with or without blast furnace slag

  7. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    NASA Astrophysics Data System (ADS)

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  8. Mercury's sodium exosphere

    Microsoft Academic Search

    F. Leblanc; R. E. Johnson

    2003-01-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to

  9. Preparation of tadpole-shaped calcium alginate microparticles with sphericity control.

    PubMed

    Dang, T D; Joo, S W

    2013-02-01

    Monosized sodium alginate microdroplets are prepared using a flow-focusing microdevice by adjusting the flow rate of the continuous phase (soybean oil) and the dispersed phase (sodium alginate solution). The gelation process of the semi-product, sodium alginate microdroplets, occurs outside the channel in a calcium chloride solution to form tadpole-shaped calcium alginate microparticles. The microparticles prepared are in the range of 100-250 ?m in diameter, depending on the experimental conditions. The shape, size and size distribution of these calcium alginate microparticles depend strongly on the calcium solution concentration and the stirring mode. The shaping mechanism of the microparticles and the impact of the experimental conditions on particle shape and size are investigated. PMID:23107954

  10. Hydration strategies, weight change and performance in a 161 km ultramarathon.

    PubMed

    Hoffman, Martin D; Stuempfle, Kristin J

    2014-01-01

    To examine controversies about hydration strategies, participants (383 starters) of a 161 km ultramarathon (maximum temperature 39.0°C) underwent body weight measurements before, during and after the race; and completed a post-race questionnaire on drinking strategies and sodium supplementation use during 4 race segments. Drinking to thirst was the most common (p < 0.01) drinking strategy (used by 67.0% during at least one segment) and most runners (95.6%) used sodium supplementation during at least one segment. There was no difference in the extent of weight loss (mean 2.0-3.1%) or the weight change pattern when comparing groups using different hydration strategies. Among top-10 finishers, half had lost more than 2% of starting body weight by 90 km. We conclude that weight loss greater than 2% does not necessarily have adverse consequences on performance, and use of sodium supplements or drinking beyond thirst is not required to maintain hydration during ultra-endurance events with high thermal stress. PMID:24950110

  11. Alternative technique for calcium phosphate coating on titanium alloy implants.

    PubMed

    Le, Van Quang; Pourroy, Geneviève; Cochis, Andrea; Rimondini, Lia; Abdel-Fattah, Wafa I; Mohammed, Hadeer I; Carradò, Adele

    2014-01-01

    As an alternative technique for calcium phosphate coating on titanium alloys, we propose to functionalize the metal surface with anionic bath containing chlorides of palladium or silver as activators. This new deposition route has several advantages such as controlled conditions, applicability to complex shapes, no adverse effect of heating, and cost effectiveness. A mixture of hydroxyapatite and calcium phosphate hydrate is deposited on the surface of Ti-6Al-4V. Calcium phosphate coating is built faster compared with the one by Simulated Body Fluid. Cell morphology and density are comparable to the control one; and the results prove no toxic compound is released into the medium during the previous seven days of immersion. Moreover, the cell viability is comparable with cells cultivated with the virgin medium. These experimental treatments allowed producing cytocompatible materials potentially applicable to manufacture implantable devices for orthopedic and oral surgeries. PMID:24646569

  12. Aluminum Citrate Prevents Renal Injury from Calcium Oxalate Crystal Deposition

    PubMed Central

    Besenhofer, Lauren M.; Cain, Marie C.; Dunning, Cody

    2012-01-01

    Calcium oxalate monohydrate crystals are responsible for the kidney injury associated with exposure to ethylene glycol or severe hyperoxaluria. Current treatment strategies target the formation of calcium oxalate but not its interaction with kidney tissue. Because aluminum citrate blocks calcium oxalate binding and toxicity in human kidney cells, it may provide a different therapeutic approach to calcium oxalate-induced injury. Here, we tested the effects of aluminum citrate and sodium citrate in a Wistar rat model of acute high-dose ethylene glycol exposure. Aluminum citrate, but not sodium citrate, attenuated increases in urea nitrogen, creatinine, and the ratio of kidney to body weight in ethylene glycol–treated rats. Compared with ethylene glycol alone, the addition of aluminum citrate significantly increased the urinary excretion of both crystalline calcium and crystalline oxalate and decreased the deposition of crystals in renal tissue. In vitro, aluminum citrate interacted directly with oxalate crystals to inhibit their uptake by proximal tubule cells. These results suggest that treating with aluminum citrate attenuates renal injury in rats with severe ethylene glycol toxicity, apparently by inhibiting calcium oxalate’s interaction with, and retention by, the kidney epithelium. PMID:23138489

  13. Aluminum citrate prevents renal injury from calcium oxalate crystal deposition.

    PubMed

    Besenhofer, Lauren M; Cain, Marie C; Dunning, Cody; McMartin, Kenneth E

    2012-12-01

    Calcium oxalate monohydrate crystals are responsible for the kidney injury associated with exposure to ethylene glycol or severe hyperoxaluria. Current treatment strategies target the formation of calcium oxalate but not its interaction with kidney tissue. Because aluminum citrate blocks calcium oxalate binding and toxicity in human kidney cells, it may provide a different therapeutic approach to calcium oxalate-induced injury. Here, we tested the effects of aluminum citrate and sodium citrate in a Wistar rat model of acute high-dose ethylene glycol exposure. Aluminum citrate, but not sodium citrate, attenuated increases in urea nitrogen, creatinine, and the ratio of kidney to body weight in ethylene glycol-treated rats. Compared with ethylene glycol alone, the addition of aluminum citrate significantly increased the urinary excretion of both crystalline calcium and crystalline oxalate and decreased the deposition of crystals in renal tissue. In vitro, aluminum citrate interacted directly with oxalate crystals to inhibit their uptake by proximal tubule cells. These results suggest that treating with aluminum citrate attenuates renal injury in rats with severe ethylene glycol toxicity, apparently by inhibiting calcium oxalate's interaction with, and retention by, the kidney epithelium. PMID:23138489

  14. Discovery of calcium in Mercury's atmosphere.

    PubMed

    Bida, T A; Killen, R M; Morgan, T H

    2000-03-01

    The composition and evolutionary history of Mercury's crust are not well determined. The planet as a whole has been predicted to have a refractory, anhydrous composition: rich in Ca, Al, Mg and Fe, but poor in Na, K, OH, and S. Its atmosphere is believed to be derived in large part from the surface materials. A combination of effects that include impact vaporization (from infalling material), volatile evaporation, photon-stimulated desorption and sputtering releases material from the surface to form the atmosphere. Sodium and potassium have already been observed in Mercury's atmosphere, with abundances that require a volatile-rich crust. The sodium probably results from photon-stimulated desorption, and has a temperature of 1,500 K (ref. 10). Here we report the discovery of calcium in the atmosphere near Mercury's poles. The column density is very low and the temperature is apparently very high (12,000 K). The localized distribution and high temperature, if confirmed, suggest that the atmospheric calcium may arise from surface sputtering by ions, which enter Mercury's auroral zone. The low abundance of atmospheric Ca may indicate that the regolith is rarefied in calcium. PMID:10724161

  15. Interaction of H2S with Calcium Permeable Channels and Transporters

    PubMed Central

    Zhang, Weihua; Xu, Changqing; Wu, Lingyun; Wang, Rui

    2015-01-01

    A growing amount of evidence has suggested that hydrogen sulfide (H2S), as a gasotransmitter, is involved in intensive physiological and pathological processes. More and more research groups have found that H2S mediates diverse cellular biological functions related to regulating intracellular calcium concentration. These groups have demonstrated the reciprocal interaction between H2S and calcium ion channels and transporters, such as L-type calcium channels (LTCC), T-type calcium channels (TTCC), sodium/calcium exchangers (NCX), transient receptor potential (TRP) channels, ?-adrenergic receptors, and N-methyl-D-aspartate receptors (NMDAR) in different cells. However, the understanding of the molecular targets and mechanisms is incomplete. Recently, some research groups demonstrated that H2S modulates the activity of calcium ion channels through protein S-sulfhydration and polysulfide reactions. In this review, we elucidate that H2S controls intracellular calcium homeostasis and the underlying mechanisms.

  16. Multiple stage multiple filter hydrate store

    DOEpatents

    Bjorkman, Jr., Harry K. (Birmingham, MI)

    1983-05-31

    An improved hydrate store for a metal halogen battery system is disclosed which employs a multiple stage, multiple filter means or separating the halogen hydrate from the liquid used in forming the hydrate. The filter means is constructed in the form of three separate sections which combine to substantially cover the interior surface of the store container. Exit conduit means is provided in association with the filter means for transmitting liquid passing through the filter means to a hydrate former subsystem. The hydrate former subsystem combines the halogen gas generated during the charging of the battery system with the liquid to form the hydrate in association with the store. Relief valve means is interposed in the exit conduit means for controlling the operation of the separate sections of the filter means, such that the liquid flow through the exit conduit means from each of the separate sections is controlled in a predetermined sequence. The three separate sections of the filter means operate in three discrete stages to provide a substantially uniform liquid flow to the hydrate former subsystem during the charging of the battery system. The separation of the liquid from the hydrate causes an increase in the density of the hydrate by concentrating the hydrate along the filter means.

  17. Deliquescence of calcium perchlorate: A route to liquid water on Mars and other possibly habitable planets

    NASA Astrophysics Data System (ADS)

    Tolbert, M.; Nuding, D.; Gough, R. V.

    2013-05-01

    The Wet Chemistry Laboratory (WCL) aboard the Phoenix Mars Lander identified the presence of 0.5% perchlorate (ClO4-). Reanalysis of the Viking gas chromatography-mass spectrometry results also suggests perchlorate was present in the soil and the Mars Science Laboratory (MSL) rover has potentially found perchlorate as well. Perchlorate salts are known to readily absorb water vapor from the atmosphere and deliquesce into an aqueous solution. We have previously performed laboratory studies to better understand the deliquescence (crystalline solid to aqueous salt) and also efflorescence (aqueous salt to crystalline solid) of several perchlorate salts at low temperatures. We found that NaClO4 and Mg(ClO4)2 are highly deliquescent, forming aqueous solutions at humidity values as low as 40% RH and at temperatures as low as 223 K. We also observed a significant hysteresis that occurs during efflorescence of these salt solutions, expected due to the kinetic inhibition of crystal nucleation. The efflorescence relative humidity values of sodium and magnesium perchlorate solutions are 13% RH and 19% RH, respectively, indicating that perchlorate salts could exist as stable or metastable aqueous solutions over a wide range of Martian RH and temperature conditions. Although the low temperature deliquescence of several perchlorate salts is now well characterized, instruments onboard Phoenix and MSL have identified calcium perchlorate (Ca(ClO4)2) as the likely parent salt. Calcium perchlorate is known for its highly deliquescent properties and low eutectic point; however, the deliquescence and efflorescence of this salt have not yet been quantified as a function of temperature. We have used Raman microscopy to examine the deliquescence and efflorescence of Ca(ClO4)2 under relevant Martian temperatures. A extremely low DRH of ~1% for the anhydrous Ca(ClO4)2 at 273 K was observed, which could allow for formation of aqueous solutions under very low RH environmental conditions. Hydrated calcium perchlorate deliquesces at higher RHs from 25-45%RH. In all cases studied, however, the aqueous solutions remain liquid until the RH decreases to a much lower value where the particle eventually effloresces. At 273 K, the ERH is less than 1% RH and on average, less than 15% RH for all temperatures studied. Understanding RH phase transition range for Ca(ClO4)2 aqueous solutions, or any briny mixture, is important for characterizing the present-day water on Mars and has implications for the availability of liquid water and the habitability of other similar planets.

  18. Formation of the anion structure of calcium hydrosilicates in hardening of slag cements

    Microsoft Academic Search

    N. S. Nikonova; V. V. Mityushin; I. N. Tikhomirova; V. I. Prikhno

    1993-01-01

    The characteristics of formation of the phase composition and anion structure of hydrate formations in hardening of composites\\u000a based on granulated electrothermal phosphorus slag and self-slaking ferrochrome slag mixed with a solution of sodium sulfate\\u000a were examined.

  19. Immediate acceptance of minerals and HCl by calcium-deprived rats: brief exposure tests.

    PubMed

    Coldwell, S E; Tordoff, M G

    1996-07-01

    We conducted two experiments to test the hypothesis that calcium consumption by calcium-deprived rats is unlearned and guided by oral cues. In experiment 1, we gave 23.5-h water-deprived control and calcium-deprived rats 30-min tests with water and various taste solutions. Relative to controls, calcium-deprived rats licked significantly less water and more 300 mM Ca.lactate in the first minute, more 50 mM HCl and 125 mM HCl in the first 10 min, and more 75 mM CaCl2, 150 mM CaCl2, and 300 mM CaCl2 by the end of the 30-min session. There was no difference between the groups at any time in lick rates for sodium solutions, quinine hydrochloride, sucrose octaacetate, or saccharin. In experiment 2, we gave 23-h water-deprived control, calcium-deprived, and sodium-deprived rats 10-min tests. During the first minute, calcium-deprived rats licked more than did control and sodium-deprived rats for 100 mM CaCl2, 100 mM FeCl2, and 20 mM Pb.acetate. Sodium-deprived rats licked more than did control and calcium-deprived rats for 600 mM NaCl and less than did controls for 200 mM L-histidine. At the end of the 10-min session, sodium-deprived rats had higher lick rates for 100 mM FeCl2 than did control rats. There were no differences between the groups in lick rates for 1 mM quinine hydrochloride, 100 mM SrCl2, or 20 mM citric acid. The results suggest that calcium-deprived rats use innate oral factors to guide consumption of calcium and other solutions. PMID:8760198

  20. Production of Lactic Acid from Raw Sweet Potato Powders by Rhizopus Oryzae Immobilized in Sodium Alginate Capsules

    Microsoft Academic Search

    Hong-Wei Yen; Yi-Chih Lee

    2010-01-01

    Rhizopus oryzae immobilized in calcium alginate was applied in lactic acid fermentation with unhydrolyzed raw sweet potato powders as the\\u000a sole carbon source. The effects of sodium alginate concentration, calcium chloride concentration, and the immobilized bead\\u000a diameter on lactic acid production were investigated. Increase in sodium alginate concentration during the gelation process\\u000a would harden the immobilized capsule, which led to

  1. Compressive strength and hydration of wastepaper sludge ash-ground granulated blastfurnace slag blended pastes

    SciTech Connect

    Bai, J.; Chaipanich, A.; Kinuthia, J.M.; O'Farrell, M.; Sabir, B.B.; Wild, S.; Lewis, M.H

    2003-08-01

    Compressive strength and hydration characteristics of wastepaper sludge ash-ground granulated blastfurnace slag (WSA-GGBS) blended pastes were investigated at a water to binder (w/b) ratio of 0.5. The strength results are compared to those of normal Portland cement (PC) paste and relative strengths are reported. Early relative strengths (1 day) of WSA-GGBS pastes were very low but a marked gain in relative strength occurred between 1 and 7 days and this increased further after 28 and 90 days. For the 50% WSA-50% GGBS blended paste, the strength achieved at 90 days was nearly 50% of that of the PC control paste. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric (TG) analysis were carried out to identify the mineral components in the WSA and the hydration products of WSA and WSA-GGBS pastes. The principal crystalline components in the WSA are gehlenite, calcium oxide, bredigite and {alpha}'-C{sub 2}S (stabilised with Al and Mg) together with small amounts of anorthite and calcium carbonate and traces of calcium hydroxide and quartz. The {alpha}'-C{sub 2}S and bredigite, which phase separate from liquid phase that forms a glass on cooling, are difficult to distinguish by XRD. The hydration products identified in WSA paste are CH, C{sub 4}AH{sub 13}, C{sub 3}A.0.5CC-bar.0.5CH.H{sub 11.5} and C-S-H gel plus possible evidence of small amounts of C{sub 2}ASH{sub 8} and C{sub 3}A.3CS-bar.H{sub 32}. Based upon the findings, a hydration mechanism is presented, and a model is proposed to explain the observed strength development.

  2. Molecular Structure of Acyclovir hydrate

    NSDL National Science Digital Library

    2002-09-12

    Acyclovir hydrate is used in the treatment of shingles and herpes simplex virus and as well as other types of herpes viral infections. This may help people co-infected with HIV and herpes simplex live longer. High dose acyclovir is used to treat hairy leukoplakia, a viral infection which usually shows up on both sides of the tongue. Possible side effects of this therapeutic substance are stomach pain, headache, nausea and/or hair-loss.

  3. Gas hydrates: Technology status report

    SciTech Connect

    Not Available

    1987-01-01

    In 1983, the US Department of Energy (DOE) assumed the responsibility for expanding the knowledge base and for developing methods to recover gas from hydrates. These are ice-like mixtures of gas and water where gas molecules are trapped within a framework of water molecules. This research is part of the Unconventional Gas Recovery (UGR) program, a multidisciplinary effort that focuses on developing the technology to produce natural gas from resources that have been classified as unconventional because of their unique geologies and production mechanisms. Current work on gas hydrates emphasizes geological studies; characterization of the resource; and generic research, including modeling of reservoir conditions, production concepts, and predictive strategies for stimulated wells. Complementing this work is research on in situ detection of hydrates and field tests to verify extraction methods. Thus, current research will provide a comprehensive technology base from which estimates of reserve potential can be made, and from which industry can develop recovery strategies. 7 refs., 3 figs., 6 tabs.

  4. Gas hydrates thermomechanics: Final report

    SciTech Connect

    Corlett, R.C.

    1988-04-01

    Solid CH4 hydrate samples can be built up by pulses of water spray onto a solid surface in a CH4 atmosphere at temperature and pressure within the hydrate stability domain. By pulse spraying into a cylindrical well, clean cylindrical samples approximately 4 cm diameter by 2.5 cm long can be obtained. There have been found experimentally simple means to achieve for such a cylindrical sample axial stress in excess above the radial and azimuthal stress imposed by gas pressure on the lateral face or excess radial and azimuthal stress above axial stress imposed by gas pressure on the end face. When uniaxially loaded on the end faces, the samples have very little strength, crushing or fracturing at excess axial stress less than 0.2 MPa, at temperatures above 0 deg C, but can withstand at least 2 MPa at temperatures below 0 deg C. These results suggest that stress anisotropy is not a significant factor in the thermomechanics behavior of gas hydrates at temperatures above 0 deg C. Samples can be temporarily depressurized below the stability envelope at temperatures below 0 deg C and then be repressurized and have temperature raised above 0 deg C without any change of appearance, whereas, at temperatures above 0 deg C, samples decompose and dramatically alter in appearance upon depressurization below the stability envelope. 6 refs., 10 figs.

  5. Study of Formation Mechanisms of Gas Hydrate

    NASA Astrophysics Data System (ADS)

    Yang, Jia-Sheng; Wu, Cheng-Yueh; Hsieh, Bieng-Zih

    2015-04-01

    Gas hydrates, which had been found in subsurface geological environments of deep-sea sediments and permafrost regions, are solid crystalline compounds of gas molecules and water. The estimated energy resources of hydrates are at least twice of that of the conventional fossil fuel in the world. Gas hydrates have a great opportunity to become a dominating future energy. In the past years, many laboratory experiments had been conducted to study chemical and thermodynamic characteristics of gas hydrates in order to investigate the formation and dissociation mechanisms of hydrates. However, it is difficult to observe the formation and dissociation of hydrates in a porous media from a physical experiment directly. The purpose of this study was to model the dynamic formation mechanisms of gas hydrate in porous media by reservoir simulation. Two models were designed for this study: 1) a closed-system static model with separated gas and water zones; this model was a hydrate equilibrium model to investigate the behavior of the formation of hydrates near the initial gas-water contact; and 2) an open-system dynamic model with a continuous bottom-up gas flow; this model simulated the behavior of gas migration and studied the formation of hydrates from flowed gas and static formation water in porous media. A phase behavior module was developed in this study for reservoir simulator to model the pressure-volume-temperature (PVT) behavior of hydrates. The thermodynamic equilibriums and chemical reactions were coupled with the phase behavior module to have functions modelling the formation and dissociation of hydrates from/to water and gas. The simulation models used in this study were validated from the code-comparison project proposed by the NETL. According to the modelling results of the closed-system static model, we found that predominated location for the formation of hydrates was below the gas-water contact (or at the top of water zone). The maximum hydrate saturation observed was located just below the gas-water contact. The open-system dynamic model showed that the hydrates were basically uniformly distributed in a homogeneous porous media at a constant gas migration rate. However, if the gas migration rate was extremely low, the hydrates will tend to concentrate at the bottom of water zone (i.e. at the first contact of the water and the flowed gas) and finally blocked the vertical flow of gas. The models we designed can be scaled up to a field scale, and the research findings from this study can be contributed to the dispersion analysis of an in-situ hydrate reservoir.

  6. Hydrate-phobic surfaces: fundamental studies in clathrate hydrate adhesion reduction

    E-print Network

    Smith, J. David

    Clathrate hydrate formation and subsequent plugging of deep-sea oil and gas pipelines represent a significant bottleneck for deep-sea oil and gas operations. Current methods for hydrate mitigation are expensive and energy ...

  7. Development of Alaskan gas hydrate resources

    SciTech Connect

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  8. HYDRATION OF GELATIN IN SOLUTION.

    PubMed

    Kunitz, M

    1927-05-20

    1. It was shown that the high viscosity of gelatin solutions as well as the character of the osmotic pressure-concentration curves indicates that gelatin is hydrated even at temperatures as high as 50 degrees C. 2. The degree of hydration of gelatin was determined by means of viscosity measurements through the application of the formula See PDF for Equation. 3. When the concentration of gelatin was corrected for the volume of water of hydration as obtained from the viscosity measurements, the relation between the osmotic pressure of various concentrations of gelatin and the corrected concentrations became linear, thus making it possible to determine the apparent molecular weight of gelatin through the application of van't Hoff's law. The molecular weight of gelatin at 35 degrees C. proved to be 61,500. 4. A study was made of the mechanism of hydration of gelatin and it was shown that the experimental data agree with the theory that the hydration of gelatin is a pure osmotic pressure phenomenon brought about by the presence in gelatin of a number of insoluble micellae containing a definite amount of a soluble ingredient of gelatin. As long as there is a difference in the osmotic pressure between the inside of the micellae and the outside gelatin solution the micellae swell until an equilibrium is established at which the osmotic pressure inside of the micellae is balanced by the total osmotic pressure of the gelatin solution and by the elasticity pressure of the micellae. 5. On addition of HCl to isoelectric gelatin the total activity of ions inside of the micellae is greater than in the outside solution due to a greater concentration of protein in the micellae. This brings about a further swelling of the micellae until a Donnan equilibrium is established in the ion distribution accompanied by an equilibrium in the osmotic pressure. Through the application of the theory developed here it was possible actually to calculate the osmotic pressure difference between the inside of the micellae and the outside solution which was brought about by the difference in the ion distribution. 6. According to the same theory the effect of pH on viscosity of gelatin should diminish with increase in concentration of gelatin, since the difference in the concentration of the protein inside and outside of the micellae also decreases. This was confirmed experimentally. At concentrations above 8 gm. per 100 gm. of H(2)O there is very little difference in the viscosity of gelatin of various pH as compared with that of isoelectric gelatin. PMID:19872362

  9. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    Microsoft Academic Search

    T. Kwon; G. Cho; J. Santamarina; H. Kim; J. Lee

    2009-01-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling\\/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution

  10. Gas hydrates in the Gulf of Mexico 

    E-print Network

    Cox, Henry Benjamin

    1986-01-01

    matter. High organic carbon (& 2%) and total sulfur (& 0. 8%) were also associated with thermogenic gas hydrate containing cores. Biogenic gas hydrates were mostly white flat sheets containing 99% methane that was isotopically light. The associated... sediment had no iv visible oil stains with bitumen levels of ( 0. 05% and total sulfur and organic carbon averaging 0. 8 and 1. 0%, respectively. Sediments of both gas hydrate types contained authigenic carbonate in the upper 1. 0 meter of the core...

  11. Study of modified calcium hydroxides for enhancing SO 2 removal during sorbent injection in pulverized coal boilers

    Microsoft Academic Search

    Juan Adánez; Vanessa Fierro; Francisco García-Labiano; JoséMaría Palacios

    1997-01-01

    Several modified calcium hydroxides were prepared by lime hydration using NaCl, KCl, calcium lignosulfonate, ethanol-water solutions and combinations of them, to obtain sorbents with enhanced capacity to remove SO2. The sorbents were characterized in a drop tube reactor in similar conditions to those existing during sorbent injection in pulverized coal boilers. The greatest increases in SO2 retention were obtained with

  12. CALCIUM EQUILIBRIUM IN MUSCLE

    PubMed Central

    Gilbert, Daniel L.; Fenn, Wallace O.

    1957-01-01

    1. A study of the calcium equilibrium in isolated frog muscle has been attempted. 2. When sartorius muscles were immersed in Ca45 Ringer's solution, the surface phase took up the Ca45 in about 1 minute; the extracellular water space and connective tissue in about 30 minutes; and the intracellular space in about 300 minutes. 3. The percentages of total calcium in the whole muscle immersed in Ringer's solution was as follows: 10 per cent in the surface phase; 12 per cent in the extracellular water space; 17 per cent in the dry connective tissue; 24 per cent in the intracellular space; and 37 per cent as non-exchangeable calcium. 4. The exchange constants of isolated frog sartorius muscle to calcium has been determined. The flux of intracellular calcium in the steady state was approximately 0.8 mM/(liter hr). 5. It appears that there is a calcium pump pushing calcium out of the cell against an electrochemical gradient of about 4 cal./mM of calcium. However, since the flux is low, the maximum energy required per hour to pump calcium out of the cell against this high gradient is only about 2 cal./kg. muscle or about 1 per cent of the resting energy. PMID:13398571

  13. Physical Properties of Gas Hydrates: A Review

    DOE PAGESBeta

    Gabitto, Jorge F.; Tsouris, Costas

    2010-01-01

    Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately1016?m3of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical datamore »collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.« less

  14. Desalination utilizing clathrate hydrates (LDRD final report).

    SciTech Connect

    Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy (Sandia National Laboratories, Albuquerque, NM); Greathouse, Jeffery A. (Sandia National Laboratories, Albuquerque, NM); Majzoub, Eric H. (University of Missouri, Columbia, MO)

    2008-01-01

    Advances are reported in several aspects of clathrate hydrate desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of hydrate guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate hydrate growth, control the morphology of the solid hydrate material formed, and facilitate separation of hydrate solids from concentrated brine. The rate of R141b hydrate formation was determined and found to depend only on the degree of supercooling. The rate of R141b hydrate formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b hydrates from brine. Preliminary experiments using the guest species, difluoromethane, showed that hydrate formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II hydrate. Additionally, the hydrate of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer hydrate. Molecular dynamics simulations show that R141b hydrate is stable at temperatures up to 265K, while the isomer hydrate is only stable up to 150K. Despite hydrogen bonding between guest and host, R141b molecules rotated freely within the water cage. The Raman spectrum of R141b in both the pure and hydrate phases was also compared with vibrational analysis from both computational methods. In particular, the frequency of the C-Cl stretch mode (585 cm{sup -1}) undergoes a shift to higher frequency in the hydrate phase. Raman spectra also indicate that this peak undergoes splitting and intensity variation as the temperature is decreased from 4 C to -4 C.

  15. Effective hydration temperature of obsidian: a diffusion theory analysis of time-dependent hydration rates

    Microsoft Academic Search

    Alexander K. Rogers

    2007-01-01

    An estimate of effective hydration temperature (EHT) is needed for chronological use of obsidian hydration data. This paper describes a method for calculating EHT by the practicing archaeologist, replacing three techniques that are in general use today: estimates based on mean temperature, numerical integration of models of diurnal and annual temperature variations, and use of temperature cells. The hydration (or

  16. The conversion process of hydrocarbon hydrates into CO2 hydrates and vice versa: thermodynamic considerations.

    PubMed

    Schicks, J M; Luzi, M; Beeskow-Strauch, B

    2011-11-24

    Microscopy, confocal Raman spectroscopy and powder X-ray diffraction (PXRD) were used for in situ investigations of the CO(2)-hydrocarbon exchange process in gas hydrates and its driving forces. The study comprises the exposure of simple structure I CH(4) hydrate and mixed structure II CH(4)-C(2)H(6) and CH(4)-C(3)H(8) hydrates to gaseous CO(2) as well as the reverse reaction, i.e., the conversion of CO(2)-rich structure I hydrate into structure II mixed hydrate. In the case of CH(4)-C(3)H(8) hydrates, a conversion in the presence of gaseous CO(2) from a supposedly more stable structure II hydrate to a less stable structure I CO(2)-rich hydrate was observed. PXRD data show that the reverse process requires longer initiation times, and structural changes seem to be less complete. Generally, the exchange process can be described as a decomposition and reformation process, in terms of a rearrangement of molecules, and is primarily induced by the chemical potential gradient between hydrate phase and the provided gas phase. The results show furthermore the dependency of the conversion rate on the surface area of the hydrate phase, the thermodynamic stability of the original and resulting hydrate phase, as well as the mobility of guest molecules and formation kinetics of the resulting hydrate phase. PMID:21928801

  17. Microbial Community Structure and Diversity in Hydrate Ridge Gas Hydrates (Cascadia Margin)

    Microsoft Academic Search

    T. Lösekann; K. Knittel; A. Boetius; R. Amann

    2003-01-01

    Here, we present the first quantitative study investigating microorganisms physically associated with Hydrate Ridge gas hydrates. Previous studies have shown that the anaerobic oxidation of methane (AOM) in methane enriched surface sediments of Hydrate Ridge is apparently mediated by highly structured microbial consortia (Boetius et al., 2000). These AOM consortia consist of an inner core of methane-oxidizing archaea (ANME2-group) and

  18. Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

    ERIC Educational Resources Information Center

    Barlag, Rebecca; Nyasulu, Frazier

    2011-01-01

    The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

  19. Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments

    USGS Publications Warehouse

    Lee, J.Y.; Yun, T.S.; Santamarina, J.C.; Ruppel, C.

    2007-01-01

    The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth behavior of gas hydrates in natural sediments. Hydrate of tetrahydrofuran (THF) has long been used for laboratory studies of gas hydrate-bearing sediments to provide close control on hydrate concentrations and to overcome the long formation history of methane hydrate from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule) compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of hydrate-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF hydrate is similar to that between water and methane hydrate. The processes that researchers choose for forming hydrate in sediments in laboratory settings (e.g., from gas, liquid, or ice) and the pore-scale distribution of the hydrate that is produced by each of these processes likely have a more pronounced effect on the measured macroscale properties of hydrate-bearing sediments than do differences between THF and methane hydrates themselves.

  20. Observations related to tetrahydrofuran and methane hydrates for laboratory studies of hydrate-bearing sediments

    NASA Astrophysics Data System (ADS)

    Lee, J. Y.; Yun, T. S.; Santamarina, J. C.; Ruppel, C.

    2007-06-01

    The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth behavior of gas hydrates in natural sediments. Hydrate of tetrahydrofuran (THF) has long been used for laboratory studies of gas hydrate-bearing sediments to provide close control on hydrate concentrations and to overcome the long formation history of methane hydrate from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule) compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of hydrate-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF hydrate is similar to that between water and methane hydrate. The processes that researchers choose for forming hydrate in sediments in laboratory settings (e.g., from gas, liquid, or ice) and the pore-scale distribution of the hydrate that is produced by each of these processes likely have a more pronounced effect on the measured macroscale properties of hydrate-bearing sediments than do differences between THF and methane hydrates themselves.

  1. The system water-sodium oxide-silicon dioxide at 200, 250, and 300??

    USGS Publications Warehouse

    Rowe, J.J.; Fournier, R.O.; Morey, G.W.

    1967-01-01

    Studies were made of the H2O-Na2O-SiO2 system at its vapor pressure at 200, 250, and 300??. Three different sodium trisilicate hydrates were encountered in the investigation. At 300??, Na2Si3O7??5H2O is found: at 250??, Na2Si3O7??6H2O; and at 200??, Na2Si3O7??11H2O. The liquid immiscibility previously reported to exist in the system was found to be a quenching phenomenon caused by the decomposition of the hydrates to unstable, supersaturated, viscous liquids. Under conditions where equilibrium is maintained, as temperature is lowered, the hydrates decompose to quartz, sodium disilicate, and liquid. The retrograde solubility of sodium disilicate and its tendency to form supersaturated solutions during heating from 25 to 250?? account for higher solubilities reported by others than were found in this study. The solubility of sodium disilicate in water is 26% at 200??, 9% at 250??, and 5% at 300??. Sodium metasilicate solubility is 38% at 200?? and 34% at 250??; this compound is incongruently soluble at 300??.

  2. Natural gas hydrates - issues for gas production and geomechanical stability 

    E-print Network

    Grover, Tarun

    2008-10-10

    Natural gas hydrates are solid crystalline substances found in the subsurface. Since gas hydrates are stable at low temperatures and moderate pressures, gas hydrates are found either near the surface in arctic regions or in deep water marine...

  3. Dietary Factors and Medullary Sponge Kidneys as Causes of the So-Called Idiopathic Renal Leak of Calcium

    Microsoft Academic Search

    Philippe Jaeger; Luc Portmann; Jean-Marie Ginalski; Michel Campiche; Peter Burckhardt

    1987-01-01

    Out of 89 stone formers with idiopathic hypercalciuria, 51 remained hypercalciuric on a low calcium diet over 5 days: a renal leak of calcium could thus have been suspected in them. Dietary factors such as high sodium or high animal protein intake, and metabolic factors such as obesity with or without hyperinsulinemia, which all might account for the hypercalciuria of

  4. Survival of Bifidobacterium longum Immobilized in Calcium Alginate Beads in Simulated Gastric Juices and Bile Salt Solution

    Microsoft Academic Search

    KI-YONG LEE; TAE-RYEON HEO

    2000-01-01

    Bifidobacterium longum KCTC 3128 and HLC 3742 were independently immobilized (entrapped) in calcium alginate beads containing 2, 3, and 4% sodium alginate. When the bifidobacteria entrapped in calcium alginate beads were exposed to simulated gastric juices and a bile salt solution, the death rate of the cells in the beads decreased proportionally with an increase in both the alginate gel

  5. Painful peripheral neuropathy and sodium channel mutations.

    PubMed

    Hoeijmakers, Janneke G J; Faber, Catharina G; Merkies, Ingemar S J; Waxman, Stephen G

    2015-06-01

    Peripheral neuropathy can lead to neuropathic pain in a subset of patients. Painful peripheral neuropathy is a debilitating disorder, reflected by a reduced quality of life. Therapeutic strategies are limited and often disappointing, as in most cases targeted treatment is not available. Elucidating pathogenetic factors for pain might provide a target for optimal treatment. Voltage-gated sodium channels NaV1.7-NaV1.9 are expressed in the small-diameter dorsal root ganglion neurons and their axons. By a targeted gene approach, missense gain-of-function mutations of NaV1.7-NaV1.9 have been demonstrated in painful peripheral neuropathy. Functional analyses have shown that these mutations produce a spectrum of pro-excitatory changes in channel biophysics, with the shared outcome at the cellular level of dorsal root ganglion hyperexcitability. Reduced neurite outgrowth may be another consequence of sodium channel mutations, and possible therapeutic strategies include blockade of sodium channels or block of reverse operation of the sodium-calcium exchanger. Increased understanding of the pathophysiology of painful peripheral neuropathy offers new targets that may provide a basis for more effective treatment. PMID:25556685

  6. Calcium and sodium distribution and movements in smooth muscle.

    PubMed

    Somlyo, A P; Wasserman, A J; Kitazawa, T; Bond, M; Shuman, H; Somlyo, A V

    1985-08-15

    Electron probe microanalysis (EPMA) has been used to study the subcellular distribution of Ca, Na, K, Cl, and Mg in smooth muscle. The EPMA results indicate that the sarcoplasmic reticulum (SR) is the major intracellular source and sink of activator Ca: norepinephrine decreases the Ca content of the junctional SR in portal vein smooth muscle. Mitochondria do not play a significant role in regulating cytoplasmic free Ca2+, but mitochondrial Ca content can be altered to a degree compatible with suggestions that fluctuations in matrix Ca contribute to the control of mitochondrial metabolism. The rise in total cytoplasmic Ca during a maintained, maximal contraction is very much greater than the rise in free Ca2+, and is probably in excess of the known binding sites available on calmodulin and myosin. Cell Ca is not increased in normal cells that are Na-loaded. The non-Donnan distribution of Cl is not due to compartmentalization, but reflects high cytoplasmic Cl. Na-loading of smooth muscle in K-free solutions is temperature dependent, and may exhibit cellular heterogeneity undetected by conventional techniques. The total cell Mg is equivalent to approximately 12 mM, and less than 50% of it can be accounted for by binding to ATP and to actin. Mitochondrial monovalent cations in smooth muscle are relatively rapidly exchangeable. PMID:2990996

  7. A sodium calcium arsenate, NaCa(AsO4)

    PubMed Central

    Lin, Jinru; Sun, Wei; Mi, Jin-Xiao; Pan, Yuanming

    2011-01-01

    The title compound, NaCa(AsO4), was synthesized using a hydro­thermal method at 633–643?K. It has a dense structure composed of alternating layers of distorted [CaO6] octa­hedra and layers of [AsO4] tetra­hedra and distorted [NaO6] octa­hedra, stacked along the a axis. The As, Ca and two O atoms lie on the mirror plane at y = 1/4 (i.e. 4c), while the Na atom lies on an inversion centre (1/2, 1/2, 0) (i.e. 4b). Each distorted [CaO6] octa­hedron shares four equatorial common O vertices with four neighboring octa­hedra, forming a layer parallel to (100), whereas each distorted [NaO6] octa­hedron shares two opposite edges with two neighboring ones, forming a chain running along [010]. Each isolated [AsO4] tetra­hedron shares two edges with two different [NaO6] octa­hedra in one [NaO6] chain and a vertex with another chain. Simultaneously the above [AsO4] tetra­hedron located in a four-membered [CaO6] ring shares one edge of its base facet with one [CaO6] octa­hedron and three corners with three other [CaO6] octa­hedra of one [CaO6] layer, and the remaining apex is shared with another [CaO6] layer. [NaO6] octa­hedra and [CaO6] octa­hedra are linked to each other by sharing edges and vertices. PMID:22199467

  8. Sodium/calcium exchange in smooth-muscle microsomal fractions.

    PubMed Central

    Morel, N; Godfraind, T

    1984-01-01

    The existence of Na+ -dependent Ca2+ transport was investigated in microsomal fractions from the longitudinal smooth muscle of the guinea-pig ileum and from the rat aorta, and its activity was compared with that of the plasmalemmal ATP-dependent Ca2+ pump previously identified in these preparations. The rate of Ca2+ release from plasmalemmal vesicles previously loaded with Ca2+ through the ATP-dependent Ca2+ pump was transiently faster in the presence of 150 mM-NaCl in the medium than in the presence of 150 mM-KCl or -LiCl or 300 mM-sucrose. Na+-loaded vesicles took up Ca2+ when an outwardly directed Na+ gradient was formed across the membrane. The Ca ionophore A23187 induced a rapid release of 85% of the sequestered Ca2+, whereas only 15% was displaced by La3+. Ca2+ accumulated by the Na+-induced Ca2+ transport was released by the addition of NaCl, but not KCl, to the medium. Ca2+ uptake in Na+-loaded vesicles was inhibited in the presence of increasing NaCl concentration in the medium. Half-maximum inhibition was observed with 28 mM-NaCl. Data fitted the Hill equation, with a Hill coefficient (h) of 1.9. Na+-induced Ca2+ uptake was a saturable function of Ca2+ concentration in the medium. Half-maximum activity was obtained with 18 microM-Ca2+ in intestinal-smooth-muscle microsomal fraction and with 50 microM-Ca2+ in aortic microsomal fraction. The results suggest that in these membrane preparations a transmembrane movement of Ca2+ can be driven by a Na+ gradient. However, the Na+-induced Ca2+ transport had a lower capacity, a lower affinity and a slower rate than the ATP-dependent Ca2+ pump. PMID:6712624

  9. Experimental observations of hydrate formation in a convection tank

    Microsoft Academic Search

    C. F. Chen; Cho Lik Chan

    2003-01-01

    Clathrate hydrates (generally abbreviated to hydrates) are crystalline compounds formed by cage-like structure of hydrogen-bonded water molecules enclosing a guest molecule of a hydrate-forming substance. Many substances such as gases and fluorocarbon refrigerants are hydrate formers. Priestly first made hydrates in water saturated with SO2 gas at 7°C in 1778. Hydrates became industrially important in 1930's when their formation caused

  10. Development of an in vitro model using calcium imaging to investigate antidotal efficacy against saxitoxin. Report September 1994September 1996

    Microsoft Academic Search

    J. A. Doebler; B. C. Dant; F. C. T. Chang

    1997-01-01

    Studies were conducted to investigate the utility of a novel in vitro system to monitor the efficacy of potential antidotes against sodium channel neurotoxins. Intracellular free calcium levels were measured in PC-12 (rat adrenal pheochromocytoma) cells utilizing a calcium imaging system with Fura-2 as the ratiometric calcium-sensitive indicator. Elevations in Ca(++) induced by high extracellular potassium (K(+)) and 4-aminopyridine (4-AP)

  11. Depolarization and calcium entry in squid giant axons.

    PubMed

    Baker, P F; Hodgkin, A L; Ridgway, E B

    1971-11-01

    1. Changes in ionized calcium in giant axons were followed by recording the light produced by injected aequorin.2. From the effect of injecting calcium buffers the internal concentration of ionized calcium was found to be about the same as in a mixture of 45 Ca EGTA:55 free EGTA, i.e. about 0.3 muM.3. After an axon had been exposed to cyanide for 50-100 min the velocity of the aequorin reaction increased about 500 times. This effect, which could be reversed rapidly by removing cyanide, was probably brought about by release of calcium from an internal store.4. Injecting 30 mumole ATP per litre of axoplasm into a cyanide-poisoned axon caused a transient lowering of light intensity; oligomycin blocked the effect.5. Raising external calcium or replacing external sodium by choline or lithium reversibly increased the light produced by axons injected with aequorin.6. Stimulation at 50-200 impulses/sec in a solution containing 112 mM-Ca caused the light intensity to increase to a new steady level; after stimulation the light intensity returned to its original level with a time constant of 10-30 sec. Similar but smaller effects were seen in solutions containing less external calcium. The recovery after stimulation is probably due to uptake of calcium by the internal store.7. Injecting 3 m-mole EGTA per litre axoplasm lowered the resting glow and abolished the aequorin response to stimulation.8. There was no light response to stimulation immediately after an axial injection of aequorin and the effect increased to a ;steady' level with a half-time of about 5 min. The conclusion is that the rise in calcium concentration resulting from stimulation is confined to the peripheral part of the axon and that the diffusion coefficient of aequorin in axoplasm is about 4 x 10(-7) cm(2)/sec.9. The increment in light per impulse often increased markedly during the course of a long experiment and there was also considerable variation between axons.10. If the light response to stimulation was small it was proportional to the frequency of stimulation; if large to the square of the frequency.11. Voltage-clamp experiments showed that the calcium entry associated with a depolarizing pulse could be divided into an early component which was abolished by tetrodotoxin (TTX), and a late component which was unaffected by this inhibitor.12. The time relations of the early calcium entry were consistent with its being a leak of calcium ions through the sodium channel; the permeability of the sodium channel to calcium was about 1% of the permeability to sodium.13. The late entry of calcium was little changed by injecting enough tetraethylammonium (TEA) to block the outward potassium current; it was greatly reduced by external concentrations of manganese which had little effect on the maximum potassium conductance.14. The voltage-response curve for the late entry of calcium had a well defined maximum and was similar in shape to the curve relating calcium entry to depolarization at the presynaptic ending (Katz & Miledi, 1969, 1970). PMID:5133953

  12. Renal Failure and Nephrocalcinosis Associated With Oral Sodium Phosphate Bowel Cleansing Clinical Patterns and Renal Biopsy Findings

    Microsoft Academic Search

    Gulfiliz Gonlusen; Hulya Akgun; Atilla Ertan; Juan Olivero; Luan D. Truong

    c Acute renal failure (ARF) is rarely reported after bowel preparation with sodium phosphate. We report a patient with mild Crohn disease (in remission), without history of renal disease, and with normal baseline renal function, who developed ARF 14 days after bowel preparation for colonoscopy with oral sodium phosphate. A renal biopsy showed multifocal calcium phosphate deposition in the re-

  13. Effect of sodium chloride on growth, ion content, and hydrogen ion extrusion activity of sunflower and jojoba roots

    Microsoft Academic Search

    P. A. Burgos; M. Roldan; I. Agui; J. P. Donaire

    1993-01-01

    The effect of sodium chloride (NaCl) on growth, internal ion content, and proton release of sunflower (Helianthus annuus L. cv. Enano) and jojoba [Simmondsia chinensis (Link) Schneid.] roots was studied in order to understand the relationship between the above parameters and salt tolerance. The increase in sodium (Na) ions concentration and the decrease in calcium (Ca) ion concentration in sunflower

  14. Disorders of Calcium Metabolism

    Microsoft Academic Search

    John F. O’Toole

    2011-01-01

    The genetic contribution to calcium metabolism is well recognized. Many of the proteins that contribute to calcium homeostasis through intestinal absorption, bone deposition and resorption, renal reabsorption and the molecules regulating these processes have been identified. Mutations in many of the genes coding for these proteins have been identified and often have clear clinical phenotypes. These mutations are generally rare

  15. Calcium signaling in neurodegeneration

    PubMed Central

    Marambaud, Philippe; Dreses-Werringloer, Ute; Vingtdeux, Valérie

    2009-01-01

    Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases. PMID:19419557

  16. Calcium Nutrition in Adolescence

    Microsoft Academic Search

    Marta Mesías; Isabel Seiquer; M. Pilar Navarro

    2011-01-01

    Adolescence is an important period of nutritional vulnerability due to increased dietary requirements for growth and development and special dietary habits. Calcium needs are elevated as a result of the intensive bone and muscular development and thus adequate calcium intake during growth is extremely important to reach the optimum peak bone mass and to protect against osteoporosis in the adult

  17. Lead in calcium supplements.

    PubMed Central

    Scelfo, G M; Flegal, A R

    2000-01-01

    Intercalibrated measurements of lead in calcium supplements indicate the importance of rigorous analytical techniques to accurately quantify contaminant exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, by as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 136 brands of supplements that were purchased in 1996. The calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesized and/or refined (chelated and nonchelated calcium). The dried products were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit of quantitation averaged 0.06 microg/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of those calcium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 microg/daily dose of calcium) in consumer products. The nonchelated synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nondetectable to 2.9 microg Pb/g calcium, and had the largest proportion of brands meeting the new criteria (85% of the antacids and 100% of the infant formulas). Images Figure 1 Figure 2 PMID:10753088

  18. Mercury Control with Calcium-Based Sorbents and Oxidizing Agents

    SciTech Connect

    Thomas K. Gale

    2005-07-01

    This Final Report contains the test descriptions, results, analysis, correlations, theoretical descriptions, and model derivations produced from many different investigations performed on a project funded by the U.S. Department of Energy, to investigate calcium-based sorbents and injection of oxidizing agents for the removal of mercury. Among the technologies were (a) calcium-based sorbents in general, (b) oxidant-additive sorbents developed originally at the EPA, and (c) optimized calcium/carbon synergism for mercury-removal enhancement. In addition, (d) sodium-tetrasulfide injection was found to effectively capture both forms of mercury across baghouses and ESPs, and has since been demonstrated at a slipstream treating PRB coal. It has been shown that sodium-tetrasulfide had little impact on the foam index of PRB flyash, which may indicate that sodium-tetrasulfide injection could be used at power plants without affecting flyash sales. Another technology, (e) coal blending, was shown to be an effective means of increasing mercury removal, by optimizing the concentration of calcium and carbon in the flyash. In addition to the investigation and validation of multiple mercury-control technologies (a through e above), important fundamental mechanism governing mercury kinetics in flue gas were elucidated. For example, it was shown, for the range of chlorine and unburned-carbon (UBC) concentrations in coal-fired utilities, that chlorine has much less effect on mercury oxidation and removal than UBC in the flyash. Unburned carbon enhances mercury oxidation in the flue gas by reacting with HCl to form chlorinated-carbon sites, which then react with elemental mercury to form mercuric chloride, which subsequently desorbs back into the flue gas. Calcium was found to enhance mercury removal by stabilizing the oxidized mercury formed on carbon surfaces. Finally, a model was developed to describe these mercury adsorption, desorption, oxidation, and removal mechanisms, including the synergistic enhancement of mercury removal by calcium.

  19. Cast Stone Formulation At Higher Sodium Concentrations

    SciTech Connect

    Fox, K. M.; Roberts, K. A.; Edwards, T. B.

    2014-02-28

    A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, including production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leachability indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the l

  20. Cast Stone Formulation At Higher Sodium Concentrations

    SciTech Connect

    Fox, K. M.; Roberts, K. A.; Edwards, T. B.

    2013-09-17

    A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, including production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leach indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the limited

  1. Cast Stone Formulation At Higher Sodium Concentrations

    SciTech Connect

    Fox, K. M.; Edwards, T. A.; Roberts, K. B.

    2013-10-02

    A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, including production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leach indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the limited

  2. Extended hydrates interaction model: Hydrate formation and the energetics of binary homogeneous nucleation

    NASA Astrophysics Data System (ADS)

    Kulmala, Markku; Lazaridis, Mihalis; Laaksonen, Ari; Vesala, Timo

    1991-06-01

    The classical hydrates interaction model presented by Jaecker-Voirol et al. is extended into systems where the gas-phase number concentrations of acid and water molecules are of the same order of magnitude. Besides the sulfuric acid-water system, the hydrogen iodide-water and the nitric acid-water systems are considered. The distribution Nh,k of hydrates containing h water and k acid molecules has been calculated as a function of relative humidity and relative acidity. An extended formula for the Gibbs free energy of droplet formation is derived. The fraction of free molecules to the total number of molecules (free molecules+hydrates) is solved numerically and therefore the equilibrium constants of hydrate formation are not needed. Hydrate formation often has a significant effect on energetics of nucleation in the acid-water systems and the extended hydrates interaction model represents a definite improvement over the older hydrates interaction model.

  3. Le calcium et le magnsium dans la secrtion gastrique du lapin, A. SALSE, F. CRAMPES, M. BEAUVILLE, P. RAYNAUD, Laboratoire de Physiologie de la Digestion et de la Nutrition, Institut

    E-print Network

    Boyer, Edmond

    Le calcium et le magnésium dans la secrétion gastrique du lapin, A. SALSE, F. CRAMPES, M. BEAUVILLE) (Beauville, Raynaud et Vernay, 1974). Nous voulons connaître l'origine et les variations du calcium et du magnésium dans cette sécrétion. Le calcium, le magnésium ainsi que le sodium, le potassium, le chlore et l

  4. The origin of high sodium bicarbonate waters in the Atlantic and Gulf Coastal Plains

    USGS Publications Warehouse

    Foster, M.D.

    1950-01-01

    Some sodium bicarbonate waters at depth in the Atlantic and Gulf Coastal Plains have the same bicarbonate content as the shallower calcium bicarbonate waters in the same formation and appear to be the result of replacement of calcium by sodium through the action of base-exchange minerals. Others, however, contain several hundred parts per million more of bicarbonate than any of the calcium bicarbonate waters and much more bicarbonate than can be attributed to solution of calcium carbonate through the action of carbon dioxide derived from the air and soil. As the waters in the Potomac group (Cretaceous) are all low in sulphate and as the environmental conditions under which the sediments of the Potomac group were deposited do not indicate that large amounts of sulphate are available for solution, it does not seem probable that carbon dioxide generated by chemical or biochemical breakdown of sulphate is responsible for the high sodium bicarbonate waters in this area. Sulphate as a source of oxygen is not necessary for the generation of carbon dioxide by carbonaceous material. Oxygen is an important constituent of carbonaceous material and carbon dioxide is a characteristic decomposition product of such material-as, for example, peat and lignite. Experimental work showed that distilled water, calcium bicarbonate water, and sodium bicarbonate water, after contact with lignite, calcium carbonate, and permutite (a base-exchange material), had all increased greatly in sodium bicarbonate content and had become similar in chemical character and in mineral content to high sodium bicarbonate waters found in the Coastal Plain. The tests indicated that carbonaceous material can act as a source of carbon dioxide, which, when dissolved in water, enables it to take into solution more calcium carbonate. If base-exchange materials are also present to replace calcium with sodium, a still greater amount of bicarbonate can be held in solution. The presence of carbonaceous material, together with calcium carbonate and base-exchange minerals in a formation is, therefore, sufficient to account for the occurrence in it of high sodium bicarbonate waters. ?? 1950.

  5. Gas Hydrates Research Project in Japan

    USGS Multimedia Gallery

    Scientists from AIST, JOGMEC, Georgia Tech, and the USGS prepare to analyze pressure cores as part of a multi-year gas hydrates research project in Japan. This photo shows the pressure core storage chambers, which contain hydrate-bearing sediment samples obtained from the Nankai Trough offshore Japa...

  6. Dissociation Rate of THF-methane Hydrates

    Microsoft Academic Search

    C. Giavarini; F. Maccioni; M. L. Santarelli

    2008-01-01

    A number of papers and research projects suggest that stranded natural gas can be transported in a solid hydrate state at higher temperatures or lower pressures compared to conventional transportation systems (LNG and CNG). The self-preservation effect of methane hydrate can probably be improved by the use of a third component besides CH4 and water. Tetrahydrofuran (THF) is a promoter

  7. Nutrition and hydration in the terminal patient.

    PubMed

    Ahronheim, J C

    1996-05-01

    Artificial nutrition and hydration (ANH) may be provided parenterally or enterally. Hydration alone can be provided intravenously (vein) or subcutaneously (hypodermocylsis). This article explores the medical myths surrounding ANH, especially the enteral route ("tube feeding"), and discusses alternative approaches. PMID:8799355

  8. The Fractal Ratio as a Metric of Nanostructure Development in Hydrating Cement Paste

    NASA Astrophysics Data System (ADS)

    Livingston, R. A.; Bumrongjaroen, W.; Allen, A. J.

    It is necessary to have appropriate metrics to quantify the development of the nanostructure in Portland cement paste. The fractal ratio, calculated from Small Angle Neutron Scattering (SANS) data, serves as such a metric. It expresses the proportion of the volume-fractal surface area of calcium-silicate-hydrate gel (C-S-H) to the surface-fractal surface area. The volume fractal develops in the scale range from ? 5 nm to ? 100 nm, and it is associated with the formation of outer product in the capillary pore space by the through-solution mechanism. The surface fractal is attributed to the surface structure formed by colloidal particles on solid substrates such as the Portland cement grains and fly ash particles. The evolution of this ratio over time provides insight into which types of hydration processes are dominant. Applied to study of the hydration of fly ash/Portland cement mixes at later ages, the fractal ratio method showed that in every case, except two, there was a reduced hydration rate due to the dilution effect. The two exceptions involved fly ash fractions with sufficient CaO to generate significant C-S-H gel by the alkali-activated reaction. In all cases the fractal ratio increased with time, indicating the production of additional C-S-H through the topochemical reaction.

  9. Effect of massive gas hydrate formation on the water isotopic fractionation of the gas hydrate system at Hydrate Ridge, Cascadia margin, offshore Oregon

    Microsoft Academic Search

    Hitoshi Tomaru; Marta E. Torres; Ryo Matsumoto; Walter S. Borowski

    2006-01-01

    Because gas hydrate is preferentially enriched in the heavy water isotopes, the ?18O and ?D values of pore waters collected from gas hydrate–bearing sediment can provide information on the abundance and mechanisms of gas hydrate formation. Pore waters sampled from deep-seated (40 to 125 mbsf) gas hydrate deposits in Hydrate Ridge during ODP Leg 204 show depletion in dissolved Cl?

  10. Effect of Varying Dietary Ratio of Sodium and Chloride on the Responses of Lactating Dairy Cows in Hot Weather

    Microsoft Academic Search

    C. E. Coppock; P. A. Grant; S. J. Portzer; Adrian Escobosa; T. E. Wehrly

    1982-01-01

    Twenty-four lactating Holstein and Jersey cows were fed concentrate mixtures formulated to supplement total diets with 1) no added sodium chloride, 2) 1.0% sodium chloride, 3) 1.14% calcium chloride, and 4) 1.45% sodium bicarbonate during a 9-wk continuous trial, Experi- ment 1. Responses measured were body temperature, respiration rate, milk yield, milk composition, and 15 blood variables to evaluate acid-base

  11. Nutrient intake and urine composition in calcium oxalate stone-forming dogs: comparison with healthy dogs and impact of dietary modification.

    PubMed

    Stevenson, Abigail E; Blackburn, Judith M; Markwell, Peter J; Robertson, William G

    2004-01-01

    Nutrient intake and urine composition were analyzed in calcium oxalate (CaOx)stone-forming and healthy control dogs to identify factors that contribute to CaOx urolithiasis. Stone-forming dogs had significantly lower intake of sodium, calcium, potassium, and phosphorus and significantly higher urinary calcium and oxalate concentrations, calcium excretion, and CaOx relative supersaturation (RSS). Feeding a diet used in the treatment of canine lower urinary tract disease for 1 month was associated with increased intake of moisture, sodium, and fat; reduced intake of potassium and calcium; and decreased urinary calcium and oxalate concentrations, calcium excretion, and CaOx RSS. No clinical signs of disease recurrence were observed in the stone-forming dogs when the diet was fed for an additional 11 months. The results suggest that hypercalciuria and hyperoxaluria contribute to the formation of CaOx uroliths in dogs and show that dietary modifications can alter this process. PMID:15578454

  12. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    SciTech Connect

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the revolutionary and new Arctic Drilling Platform in search of gas hydrate and free gas accumulations at depths of approximately 1200 to 2500 ft MD. A secondary objective was the gas-charged sands of the uppermost Campanian interval at approximately 3000 ft. Summary results of geophysical analysis of the well are presented in this report.

  13. Variation of corneal refractive index with hydration

    NASA Astrophysics Data System (ADS)

    Kim, Young L.; Walsh, Joseph T., Jr.; Goldstick, Thomas K.; Glucksberg, Matthew R.

    2004-03-01

    We report the effect of changes in the corneal hydration on the refractive index of the cornea. Using optical coherence tomography (OCT), the geometrical thickness and the group refractive index of the bovine cornea were derived simultaneously as the corneal hydration was varied. The corneal hydration was then calculated from the corneal thickness. The group refractive index of the cornea increased non-linearly as the cornea dehydrated. In addition, a simple mathematical model was developed, based on the assumption that changes in corneal hydration occur only in the interfibrilar space with constant water content within the collagen fibrils. Good agreement between the experimental results and the mathematical model supports the assumption. The results also demonstrate that the measurement of refractive index is a quantitative indicator of corneal hydration.

  14. Low temperature preparation of calcium phosphate structure via phosphorization of 3D-printed calcium sulfate hemihydrate based material

    Microsoft Academic Search

    J. Suwanprateeb; W. Suvannapruk; K. Wasoontararat

    2010-01-01

    The conversion of newly developed three dimensionally printed calcium sulfate hemihydrate (70–90% wt\\/wt CaSO4·0.5·H2O) based materials to calcium phosphate bioceramics by phosphorization in di-sodium hydrogen phosphate solution at 80°C for\\u000a 4, 8, 16 and 24 h was studied. It was found that transformation rate, phase composition and mechanical properties were influenced\\u000a by porosity in the fabricated samples and by the duration of

  15. CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING ON LEFT, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT OF CENTER WITH TOP OF SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  16. Observation of dynamic crossover and dynamic heterogeneity in hydration water confined in aged cement paste

    SciTech Connect

    Zhang, Y [Massachusetts Institute of Technology (MIT); Lagi, M [Massachusetts Institute of Technology (MIT); Ridi, F [University of Florence; Fratini, E [University of Florence; Baglioni, P [University of Florence; Mamontov, Eugene [ORNL; Chen, SH [Massachusetts Institute of Technology (MIT)

    2008-11-01

    High resolution quasi-elastic neutron scattering is used to investigate the slow dynamics of hydration water confined in calcium silicate hydrate gel in an aged cement paste at supercooled temperatures. A super-Arrhenius to Arrhenius dynamic crossover of the average translational relaxation time <{tau}> as a function of the inverse temperature is observed at T{sub L} = 231 {+-} 5 K, which coincides with a prominent peak in the differential scanning calorimetry cooling scan. The dynamic susceptibility {chi}{sub T}({tau}) calculated using the experimentally determined temperature dependence of the self-intermediate scattering function shows direct evidence of the enhanced dynamic fluctuations and the associated growth in size of the dynamic heterogeneity in the confined water on approaching T{sub L}.

  17. Mercury's sodium exosphere

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Johnson, R. E.

    2003-08-01

    Mercury's neutral sodium exosphere is simulated using a comprehensive 3D Monte Carlo model following sodium atoms ejected from Mercury's surface by thermal desorption, photon stimulated desorption, micro-meteoroid vaporization and solar wind sputtering. The evolution of the sodium surface density with respect to Mercury's rotation and its motion around the Sun is taken into account by considering enrichment processes due to surface trapping of neutrals and ions and depletion of the sodium available for ejection from the surfaces of grains. The change in the sodium exosphere is calculated during one Mercury year taking into account the variations in the solar radiation pressure, the photo-ionization frequency, the solar wind density, the photon and meteoroid flux intensities, and the surface temperature. Line-of-sight column densities at different phase angles, the supply rate of new sodium, average neutral and ion losses over a Mercury year, surface density distribution and the importance of the different processes of ejection are discussed in this paper. The sodium surface density distribution is found to become significantly nonuniform from day to night sides, from low to high latitudes and from morning to afternoon because of rapid depletion of sodium atoms in the surfaces of grains mainly driven by thermal depletion. The shape of the exosphere, as it would be seen from the Earth, changes drastically with respect to Mercury's heliocentric position. High latitude column density maxima are related to maxima in the sodium surface concentration at high latitudes in Mercury's surface and are not necessarily due to solar wind sputtering. The ratio between the sodium column density on the morning side of Mercury's exosphere and the sodium column density on the afternoon side is consistent with the conclusions of Sprague et al. (1997, Icarus 129, 506-527). The model, which has no fitting parameters, shows surprisingly good agreement with recent observations of Potter et al. (2002, Meteor. Planet. Sci. 8, 3357-3374) successfully explaining their velocity and column density profiles vs. heliocentric distance. Comparison with this data allows us to constrain the supply rate of new sodium atoms to the surface. We also discuss the possible origins of the strong high latitude emissions (Potter and Morgan, 1990, Science 248, 835-838; 1997a, Adv. Space Res. 19, 1571-1576; 1997b, Planet. Space Sci. 45, 95-100; Sprague et al., 1998, Icarus 135, 60-68) and the strong variations of the total content of the sodium exosphere on short (Potter et al., 1999, Planet. Space Sci. 47, 1441-1449) and long time scales (Sprague et al., 1997, Icarus 129, 506-527).

  18. Gas Hydrate Storage of Natural Gas

    SciTech Connect

    Rudy Rogers; John Etheridge

    2006-03-31

    Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a lower heat transfer rate in the internal heat exchanger than was designed. It is believed that the fins on the heat-exchanger tubes did not make proper contact with the tubes transporting the chilled glycol, and pairs of fins were too close for interior areas of fins to serve as hydrate collection sites. A correction of the fabrication fault in the heat exchanger fin attachments could be easily made to provide faster formation rates. The storage success with the POC process provides valuable information for making the process an economically viable process for safe, aboveground natural-gas storage.

  19. Clathrate hydrate tuning for technological purposes

    NASA Astrophysics Data System (ADS)

    di Profio, Pietro; Germani, Raimondo; Savelli, Gianfranco

    2010-05-01

    Gas hydrates are being increasingly considered as convenient media for gas storage and transportation as the knowledge of their properties increases, in particular as relates to methane and hydrogen. Clathrate hydrates may also represent a feasible sequestration technology for carbon dioxide, due to a well defined P/T range of stability, and several research programs are addressing this possibility. Though the understanding of the molecular structure and supramolecular interactions which are responsible of most properties of hydrates have been elucitated in recent years, the underlying theoretical physico-chemical framework is still poor, especially as relates to the role of "conditioners" (inhibitors and promoters) from the molecular/supramolecular point of view. In the present communication we show some results from our research approach which is mainly focused on the supramolecular properties of clathrate hydrate systems - and their conditioners - as a way to get access to a controlled modulation of the formation, dissociation and stabilization of gas hydrates. In particular, this communication will deal with: (a) a novel, compact apparatus for studying the main parameters of formation and dissociation of gas hydrates in a one-pot experiment, which can be easily and rapidly carried out on board of a drilling ship;[1] (b) the effects of amphiphile molecules (surfactants) as inhibitors or promoters of gas hydrate formation;[2] (c) a novel nanotechnology for a reliable and quick production of hydrogen hydrates, and its application to fuel cells;[3,4] and (d) the development of a clathrate hydrate tecnology for the sequestration and geological storage of man-made CO2, possibly with concomitant recovery of natural gas from NG hydrate fields. Furthermore, the feasibility of catalyzing the reduction of carbon dioxide to energy-rich species by hydrates is being investigated. [1] Di Profio, P., Germani, R., Savelli, G., International Patent Application PCT/IT2006/000274 [2] Di Profio P., Arca S., Germani R., Savelli G., 2005, "Surfactant promoting effects on clathrate hydrate formation: are micelles really involved?", Chem. Eng. Sci., 60, pp. 4141-4145 [3] Di Profio P., Arca S., Germani R., Savelli G., 2006, "Novel Nanostructured Media for Gas Storage and Transport: Clathrate Hydrates of Methane and Hydrogen", J. Fuel Cell Sci. & Tech., February 2007, vol. 4. [4] Di Profio, P., Germani, R., Savelli, G., EP07010346.

  20. The B-DNA Dodecamer at High Resolution Reveals a Spine of Water on Sodium, Xiuqi Shui, Lori McFail-Isom, Gary G. Hu, and Loren Dean Williams*

    E-print Network

    Williams, Loren

    The B-DNA Dodecamer at High Resolution Reveals a Spine of Water on Sodium, Xiuqi Shui, Lori Mc. Biol. 151, 535-556] that the spine of hydration in AT tract DNA is two layers deep. However, our results suggest that the primary spine is partially occupied by sodium ions. We suggest that many sequence

  1. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    USGS Publications Warehouse

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  2. [Determination of hydration number of methane hydrates using micro-laser Raman spectroscopy].

    PubMed

    Liu, Chang-Ling; Ye, Yu-Guang; Meng, Qing-Guo

    2010-04-01

    Methane hydrates are clathrate compounds that are formed by methane molecules and water molecules under low temperature and high pressure conditions. It was found that methane hydrates exist widely in sea-shelf floor and permafrost, and are considered as a potential energy resource. In the crystal lattice of clathrate hydrate, the water molecules form both large cages (5(12)6(2)) and small cages (5(12)) under the interaction of the hydrogen-hydrogen bond. In this paper, the authors designed a set of experimental apparatus for methane hydrates formation. Based on this equipment, the authors synthesized a series of methane hydrates in various systems in laboratory, including SDS solution (3% Wt) and methane, powdered ice and methane, and powdered ice and methane and natural sand with various sizes (i. e. 250-350, 180-250, 125-180 and 63-90 microm), under different temperature and pressure. The authors also designed a small device which was proved to be convenient for Raman determination of the methane hydrates. Raman spectroscopy was used to analyze the methane hydrates and to measure the structural parameters such as hydration numbers and cage occupancies. The results show that the methane hydrate samples are all in structure I type, and hydration numbers and cage occupancies are almost independent of the sediment sizes. In the three systems, the large cages of methane hydrate samples are nearly full occupied, with the occupancy ratios larger than 97%, whereas the small cages between 80% and 86%. The hydration numbers of these methane hydrate samples are between 6.05 and 6.15. PMID:20545140

  3. Models for Amorphous Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Sinha, Sourabh

    Many species e.g. sea urchin form amorphous calcium carbonate (ACC) precursor phases that subsequently transform into crystalline CaCO3. It is certainly possible that the biogenic ACC might have more than 10 wt% Mg and ˜3 wt% of water. The structure of ACC and the mechanisms by which it transforms to crystalline phase are still poorly understood. In this dissertation our goal is to determine an atomic structure model that is consistent with diffraction and IR measurements of ACC. For this purpose a calcite supercell with 24 formula units, containing 120 atoms, was constructed. Various configurations with substitution of Ca by 6 Mg ions (6 wt.%) and insertion of 3-5 H 2O molecules (2.25-3.75 wt.%) in the interstitial positions of the supercell, were relaxed using a robust density function code VASP. The most noticeable effects were the tilts of CO3 groups and the distortion of Ca sub-lattice, especially in the hydrated case. The distributions of Ca-Ca nearest neighbor distance and CO3 tilts were extracted from various configurations. The same methods were also applied to aragonite. Sampling from the calculated distortion distributions, we built models for amorphous calcite/aragonite of size ˜ 1700 nm3 based on a multi-scale modeling scheme. We used these models to generate diffraction patterns and profiles with our diffraction code. We found that the induced distortions were not enough to generate a diffraction profile typical of an amorphous material. We then studied the diffraction profiles from several nano-crystallites as recent studies suggest that ACC might be a random array of nano-cryatallites. It was found that the generated diffraction profile from a nano-crystallite of size ˜ 2 nm3 is similar to that from the ACC.

  4. Calcium oxyhalide batteries - a review

    Microsoft Academic Search

    Peled

    1983-01-01

    The electrochemistry, safety aspects and performance of calcium-thionyl chloride (TC) and calcium sulfuryl chloride (SC) batteries containing lithium or calcium based electrolytes are reviewed. In Ca -oxyhalide solutions, the calcium anode is covered by CaClâ passivating layer which is a good ionic conductor and good electronic insulator. Therefore it is called Solid Electrolyte Interphase (SEI) and these batteries are called

  5. Rare earth element geochemistry in cold-seep pore waters of Hydrate Ridge, northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Himmler, Tobias; Haley, Brian A.; Torres, Marta E.; Klinkhammer, Gary P.; Bohrmann, Gerhard; Peckmann, Jörn

    2013-07-01

    The concentrations of rare earth elements (REEs), sulphate, hydrogen sulphide, total alkalinity, calcium, magnesium and phosphate were measured in shallow (<12 cm below seafloor) pore waters from cold-seep sediments on the northern and southern summits of Hydrate Ridge, offshore Oregon. Downward-decreasing sulphate and coevally increasing sulphide concentrations reveal sulphate reduction as dominant early diagenetic process from ~2 cm depth downwards. A strong increase of total dissolved REE (?REE) concentrations is evident immediately below the sediment-water interface, which can be related to early diagenetic release of REEs into pore water resulting from the re-mineralization of particulate organic matter. The highest pore water ?REE concentrations were measured close to the sediment-water interface at ~2 cm depth. Distinct shale-normalized REE patterns point to particulate organic matter and iron oxides as main REE sources in the upper ~2-cm depth interval. In general, the pore waters have shale-normalized patterns reflecting heavy REE (HREE) enrichment, which suggests preferential complexation of HREEs with carbonate ions. Below ~2 cm depth, a downward decrease in ?REE correlates with a decrease in pore water calcium concentrations. At this depth, the anaerobic oxidation of methane (AOM) coupled to sulphate reduction increases carbonate alkalinity through the production of bicarbonate, which results in the precipitation of carbonate minerals. It seems therefore likely that the REEs and calcium are consumed during vast AOM-induced precipitation of carbonate in shallow Hydrate Ridge sediments. The analysis of pore waters from Hydrate Ridge shed new light on early diagenetic processes at cold seeps, corroborating the great potential of REEs to identify geochemical processes and to constrain environmental conditions.

  6. Copper, aluminum, iron and calcium inhibit human acetylcholinesterase in vitro.

    PubMed

    Pohanka, Miroslav

    2014-01-01

    Acetylcholinesterase (AChE) is an important part of cholinergic nerves where it participates in termination of neurotransmission. AChE can be inhibited by e.g. some Alzheimer disease drugs, nerve agents, and secondary metabolites. In this work, metal salts aluminum chloride, calcium chloride, cupric chloride, ferric chloride, potassium chloride, magnesium chloride and sodium chloride were tested for their ability to inhibit AChE. Standard Ellman assay based on human recombinant AChE was done and inhibition was measured using Dixon plot. No inhibition was proved for sodium, potassium and magnesium ions. However, aluminum, cupric, ferric and calcium ions were able to inhibit AChE via noncompetitive mechanism of inhibition. Though the inhibition is much weaker when compared to e.g. drugs with noncompetitive mechanism of action, biological relevance of the findings can be anticipated. PMID:24473150

  7. Production of caseinophosphopeptides (CPPs) from sodium caseinate using a range of commercial protease preparations

    Microsoft Academic Search

    David McDonagh; Richard J FitzGerald

    1998-01-01

    Sodium caseinate hydrolysates were generated at laboratory-scale using 28 commercial protease preparations of bacterial, fungal, plant and animal origin. Caseinophosphopeptides (CPPs) were enriched from these hydrolysates by calcium chloride aggregation at pH 7.5 followed by ethanol precipitation of the aggregates. CPP yield ranged from 3.4 to 16.0% (w\\/w) of the original protein. The calcium binding and solubilising abilities of the

  8. Mechanisms for thermal conduction in hydrogen hydrate

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Gorman, Paul D.; MacElroy, J. M. D.

    2012-01-01

    Extensive equilibrium molecular dynamics simulations have been performed to investigate thermal conduction mechanisms via the Green-Kubo approach for (type II) hydrogen hydrate, at 0.05 kbar and between 30 and 250 K, for both lightly filled H2 hydrates (1s4l) and for more densely filled H2 systems (2s4l), in which four H2 molecules are present in the large cavities, with respective single- and double-occupation of the small cages. The TIP4P water model was used in conjunction with a fully atomistic hydrogen potential along with long-range Ewald electrostatics. It was found that substantially less damping in guest-host energy transfer is present in hydrogen hydrate as is observed in common type I clathrates (e.g., methane hydrate), but more akin in to previous results for type II and H methane hydrate polymorphs. This gives rise to larger thermal conductivities relative to common type I hydrates, and also larger than type II and H methane hydrate polymorphs, and a more crystal-like temperature dependence of the thermal conductivity.

  9. Gas Hydrates Research Programs: An International Review

    SciTech Connect

    Jorge Gabitto; Maria Barrufet

    2009-12-09

    Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource. There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration. The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included.

  10. [Sodium and hypertension].

    PubMed

    de Wardener, H E

    1996-09-01

    Over several million years the human race was programmed to eat a diet which contained about 15 mmol of sodium (1 g of sodium chloride) per day. It is only five to ten thousand years ago that we became addicted to salt. Today we eat about 150 mmol of sodium (9-12 g of salt) per day. It is now apparent that this sudden rise in sodium intake (in evolutionary terms) is the most likely cause for the rise in blood pressure with age that occurs in the majority of the world's population. Those which consume less than 60 mmol/day do not develop hypertension. The reason for the rise in sodium intake is not known but it is probable that an important stimulus was the discovery that meat could be preserved by immersion into a concentrated salt solution. This seemingly miraculous power endowed salt with such magical and medicinal qualities that it became a symbol of goodness and health. It was not until 1904 Ambard and Beaujard suggested that on the contrary dietary salt could be harmful and raise the blood pressure. At first the idea did not prosper and it continues to be opposed by a diminishing band. The accumulated evidence that sodium intake is related to the blood pressure in normal man and animals and in inherited forms of hypertension has been obtained from experimental manipulations and studies of human populations. The following observation links sodium and hypertension. An increase in sodium intakes raises the blood pressure of the normal rat, dog, rabbit, baboon, chimpanzee and man. Population studies have demonstrated a significant correlation between sodium intake and the customary rise in blood pressure with age. The development of hypertensive strains of rats has revealed that the primary genetic lesion which gives rise to hypertension resides in the kidney where it impairs the urinary excretion of sodium. There is similar but less convincing evidence in essential hypertension. The kidney in both essential hypertension and hypertensive strains of rats share a number of functional abnormalities most of which are capable of impairing sodium excretion. Essential hypertension would appear to be as much a renal disturbance related to the intake of sodium as hypertension secondary to renal disease. PMID:8952809

  11. Submersible sodium pump

    DOEpatents

    Brynsvold, G.V.; Lopez, J.T.; Olich, E.E.; West, C.W.

    1989-11-21

    An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates. 14 figs.

  12. An Altered Mode of Calcium coordination in methionine-oxidized calmodulin

    SciTech Connect

    Jones, Eric M.; Squier, Thomas C.; Sacksteder, Colette A.

    2008-08-15

    Oxidation of methionine residues in calmodulin (CaM) under oxidative stress diminishes the productive association of CaM with targets and lowers the affinity for calcium. To define the structural consequences of CaM oxidation, we have used infrared difference spectroscopy to identify oxidation-dependent changes in both CaM conformation and calcium coordination. An oxidation-induced increase in the hydration of ?-helices is reflected in the downshift of the amide I’ band of both apo- and Ca2+ CaM, however the overall native fold is retained upon calcium binding. Shifts in the antisymmetric carboxylate band upon CaM oxidation indicate differential modification of calcium liganding by two classes of aspartates consistant with a model where: an Asp, at position 1 of the EF-loop, experiences diminished hydrogen bonding with the polypeptide backbone; while the second, at position 3 or 5 in the EF-loop, forms a pseudobridging coordination with a calcium-bound water molecule. The bidentate coordination of calcium by conserved glutamates is unaffected by oxidation. The observed changes in calcium ligation are discussed in terms of the placement of methionine side chains relative to the calcium binding sites, which suggests that varying sensitivities of the binding sites to oxidation may underlie the loss of CaM function upon oxidation.

  13. Carbon dioxide clathrate hydrates: selective role of intermolecular interactions and action of the SDS catalyst.

    PubMed

    Albertí, M; Pirani, F; Laganà, A

    2013-08-15

    The ability of a single sodium dodecyl sulfate (SDS) molecule to promote the formation of CO2 clathrate hydrates in water (as it does for methane) has been investigated at the microscopic level. For this purpose, the components of the related force field were carefully formulated and assembled following the procedure previously adopted for methane. The properties of the whole system (as well as those of its components) were analyzed by carrying out extended molecular dynamics calculations. Contrary to what happens for methane, the calculations singled out the propensity of CO2 (pure) water clusters to form clathrate hydrate-like structures and the disappearance of such propensity when a single SDS molecule is added to the clusters. This feature was found to be due to the strong interaction of carbon dioxide with the additive that makes the SDS molecule lose its shape together with its ability to drive water molecules to form a suitable cage. PMID:23635031

  14. Influence of Förster-type energy transfer on the vibrational relaxation of anionic hydration shells

    NASA Astrophysics Data System (ADS)

    Lotze, Stephan; Bakker, Huib J.

    2013-07-01

    We study the influence of Förster energy transfer on the vibrational relaxation dynamics of anionic hydration shells by performing time-resolved mid-infrared spectroscopy on the OH-stretch vibration of water molecules in aqueous solutions of sodium iodide. We observe that the Förster energy transfer leads to a pronounced acceleration of the vibrational relaxation. We describe the observed dynamics with a model in which we include the Förster vibrational energy transfer between the different hydroxyl groups in solution. With this model we can quantitatively describe the experimental data over a wide range of isotopic compositions and salt concentrations. Our results show that resonant energy transfer is an efficient mechanism assisting in the vibrational relaxation of anionic hydration shells.

  15. Assessment of phase formation in alkali activated low and high calcium fly ashes in building materials

    Microsoft Academic Search

    Frank Winnefeld; Andreas Leemann; Martin Lucuk; Pavel Svoboda; Markus Neuroth

    2010-01-01

    The alkali activation of one low calcium hard coal fly ash and four high calcium lignite coal fly ashes was studied by means of conduction calorimetry, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy to assess their potential for mortar and concrete production. The ashes were activated by different additions of sodium silicate with a molar SiO2\\/Na2O ratio of 1.0.

  16. Spreading of human endothelial cells on fibronectin or vitronectin triggers elevation of intracellular free calcium

    Microsoft Academic Search

    Martin Alexander Schwartz

    1993-01-01

    Intracellular calcium ((Ca2+)i) was measured in FURA 2-loaded endothelial cells plated on fibronectin or vitronectin. Average values for (Ca2+)i increased totwofold above basal levels by ~1 h after plating, and then declined. The increase in (Ca2+)i re- quired extracellular calcium. Substituting potassium for sodium in the medium reduced the elevation of (Ca2+)i, a result that rules out the involvement of

  17. Calcium magnesium acetate production and cost reduction

    SciTech Connect

    Leuschner, A.P.

    1988-02-01

    The New York State Energy Research and Development Authority (Energy Authority), Consolidated Edison Company of New York, Inc. (ConEd), the New York State Department of Transportation (NYSDOT), the New York State Thruway Authority (NYSTA), Chevron Chemical Company, the National Corn Growers Association (NCGA), and the Massachusetts Department of Public Works (MDPW) sponsored a research program to develop technology capable of producing Calcium Magnesium Acetate (CMA), an alternative road deicer, at a quality and cost which will allow its increased use. The objectives of this program were to determine the feasibility of: (1) producing CMA from regionally available waste and low grade organic feedstocks via biochemical engineering technologies; (2) operating the fermentation at concentrated product levels to reduce energy requirements and minimize drying process costs; (3) using this production approach to produce an environmentally acceptable CMA product; and (4) using and adapting an existing facility for a CMA commercial demonstration plant. The experimental program included:(1) selection of microorganisms for their ability to grow in the absence of sodium chloride and to tolerate high concentrations of calcium, magnesium, and acetate ions; (2) analysis of waste feedstocks for their potential conversion to acetate; (3) analysis of waste organic material for impurities in CMA that could carry over into the environment; (4) batch experiments to determine pH tolerance, growth in the absence of sodium chloride (NaCl), tolerance to magnesium, calcium and acetate ions, effect of substrate concentration, acid distribution, and acid production; and (5) semi-continuous laboratory scale anaerobic digestion experiments to determine loading rates, conversion efficiencies, and other design data. 67 refs., 33 figs., 66 tabs.

  18. A study of the hydration of the alkali metal ions in aqueous solution.

    PubMed

    Mähler, Johan; Persson, Ingmar

    2012-01-01

    The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR measurements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O-D stretching bands of partially deuterated water bound to these metal ions and the O-D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M-O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. A thorough analysis of M-O bond distances in solid alkali metal compounds with ligands binding through oxygen has been made from available structure databases. There is relatively strong correlation between M-O bond distances and coordination numbers also for the alkali metal ions even though the M-O interactions are weak and the number of complexes of potassium, rubidium and cesium with well-defined coordination geometry is very small. The mean M-O bond distance in the hydrated sodium, potassium, rubidium and cesium ions in aqueous solution have been determined to be 2.43(2), 2.81(1), 2.98(1) and 3.07(1) Å, which corresponds to six-, seven-, eight- and eight-coordination. These coordination numbers are supported by the linear relationship of the hydration enthalpies and the M-O bond distances. This correlation indicates that the hydrated lithium ion is four-coordinate in aqueous solution. New ionic radii are proposed for four- and six-coordinate lithium(I), 0.60 and 0.79 Å, respectively, as well as for five- and six-coordinate sodium(I), 1.02 and 1.07 Å, respectively. The ionic radii for six- and seven-coordinate K(+), 1.38 and 1.46 Å, respectively, and eight-coordinate Rb(+) and Cs(+), 1.64 and 1.73 Å, respectively, are confirmed from previous studies. The M-O bond distances in dimethyl sulfoxide solvated sodium, potassium, rubidium and cesium ions in solution are very similar to those observed in aqueous solution. PMID:22168370

  19. A Study of the Hydration of the Alkali Metal Ions in Aqueous Solution

    PubMed Central

    2011-01-01

    The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR measurements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O–D stretching bands of partially deuterated water bound to these metal ions and the O–D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M–O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. A thorough analysis of M–O bond distances in solid alkali metal compounds with ligands binding through oxygen has been made from available structure databases. There is relatively strong correlation between M–O bond distances and coordination numbers also for the alkali metal ions even though the M–O interactions are weak and the number of complexes of potassium, rubidium and cesium with well-defined coordination geometry is very small. The mean M–O bond distance in the hydrated sodium, potassium, rubidium and cesium ions in aqueous solution have been determined to be 2.43(2), 2.81(1), 2.98(1) and 3.07(1) Å, which corresponds to six-, seven-, eight- and eight-coordination. These coordination numbers are supported by the linear relationship of the hydration enthalpies and the M–O bond distances. This correlation indicates that the hydrated lithium ion is four-coordinate in aqueous solution. New ionic radii are proposed for four- and six-coordinate lithium(I), 0.60 and 0.79 Å, respectively, as well as for five- and six-coordinate sodium(I), 1.02 and 1.07 Å, respectively. The ionic radii for six- and seven-coordinate K+, 1.38 and 1.46 Å, respectively, and eight-coordinate Rb+ and Cs+, 1.64 and 1.73 Å, respectively, are confirmed from previous studies. The M–O bond distances in dimethyl sulfoxide solvated sodium, potassium, rubidium and cesium ions in solution are very similar to those observed in aqueous solution. PMID:22168370

  20. Clathrate hydrates in cometary nuclei and porosity

    NASA Technical Reports Server (NTRS)

    Smoluchowski, R.

    1988-01-01

    Possible mechanisms of formation and decomposition of CO2-clathrate hydrate in cometary nuclei are discussed. As far as it is known, this is the only clathrate hydrate which is unstable at low temperatures. Calculation shows that, in accord with other evidence, neither volume nor grain boundary diffusion in the clathrate lattice can be responsible for the rate of these reactions and that a surface mechanism with the attendant sensitivity to pressure must play a crucial role. Density changes accompanying CO2-clathrate decomposition and formation can lead to microporosity and enhanced brittleness or even to fracture of cometary nuclei at low temperatures. Other clathrate hydrates and mixed clathrates are also discussed.

  1. Seismic imaging of gas hydrate reservoir heterogeneities

    NASA Astrophysics Data System (ADS)

    Huang, Jun-Wei

    Natural gas hydrate, a type of inclusion compound or clathrate, are composed of gas molecules trapped within a cage of water molecules. The presence of gas hydrate has been confirmed by core samples recovered from boreholes. Interests in the distribution of natural gas hydrate stem from its potential as a future energy source, geohazard to drilling activities and their possible impact on climate change. However the current geophysical investigations of gas hydrate reservoirs are still too limited to fully resolve the location and the total amount of gas hydrate due to its complex nature of distribution. The goal of this thesis is twofold, i.e., to model (1) the heterogeneous gas hydrate reservoirs and (2) seismic wave propagation in the presence of heterogeneities in order to address the fundamental questions: where are the location and occurrence of gas hydrate and how much is stored in the sediments. Seismic scattering studies predict that certain heterogeneity scales and velocity contrasts will generate strong scattering and wave mode conversion. Vertical Seismic Profile (VSP) techniques can be used to calibrate seismic characterization of gas hydrate expressions on surface seismograms. To further explore the potential of VSP in detecting the heterogeneities, a wave equation based approach for P- and S-wave separation is developed. Tests on synthetic data as well as applications to field data suggest alternative acquisition geometries for VSP to enable wave mode separation. A new reservoir modeling technique based on random medium theory is developed to construct heterogeneous multi-variable models that mimic heterogeneities of hydrate-bearing sediments at the level of detail provided by borehole logging data. Using this new technique, I modeled the density, and P- and S-wave velocities in combination with a modified Biot-Gassmann theory and provided a first order estimate of the in situ volume of gas hydrate near the Mallik 5L-38 borehole. Our results suggest a range of 528 to 768x10 6 m3/km2 of natural gas trapped within hydrate, nearly an order of magnitude lower than earlier estimates which excluded effects of small-scale heterogeneities. Further, the petrophysical models are combined with a 3-D Finite Difference method to study seismic attenuation. Thus a framework is built to further tune the models of gas hydrate reservoirs with constraints from well logs other disciplinary data.

  2. Tapping methane hydrates for unconventional natural gas

    USGS Publications Warehouse

    Ruppel, Carolyn

    2007-01-01

    Methane hydrate is an icelike form of concentrated methane and water found in the sediments of permafrost regions and marine continental margins at depths far shallower than conventional oil and gas. Despite their relative accessibility and widespread occurrence, methane hydrates have never been tapped to meet increasing global energy demands. With rising natural gas prices, production from these unconventional gas deposits is becoming economically viable, particularly in permafrost areas already being exploited for conventional oil and gas. This article provides an overview of gas hydrate occurrence, resource assessment, exploration, production technologies, renewability, and future challenges.

  3. Calcium, Bone, and Life

    Microsoft Academic Search

    Robert P. Heaney

    \\u000a Calcium is a divalent mineral cation that functions as an intracellular messenger in virtually all life forms. In multicellular\\u000a organisms it functions also as an integrator tying body systems together, and in land-living vertebrates it provides the principal\\u000a mineral component of the endoskeleton (bone). Calcium cannot be synthesized and must be ingested, first to build an adult\\u000a skeleton and then

  4. Methane hydrate formation in partially water-saturated Ottawa sand

    USGS Publications Warehouse

    Waite, W.F.; Winters, W.J.; Mason, D.H.

    2004-01-01

    Bulk properties of gas hydrate-bearing sediment strongly depend on whether hydrate forms primarily in the pore fluid, becomes a load-bearing member of the sediment matrix, or cements sediment grains. Our compressional wave speed measurements through partially water-saturated, methane hydrate-bearing Ottawa sands suggest hydrate surrounds and cements sediment grains. The three Ottawa sand packs tested in the Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI) contain 38(1)% porosity, initially with distilled water saturating 58, 31, and 16% of that pore space, respectively. From the volume of methane gas produced during hydrate dissociation, we calculated the hydrate concentration in the pore space to be 70, 37, and 20% respectively. Based on these hydrate concentrations and our measured compressional wave speeds, we used a rock physics model to differentiate between potential pore-space hydrate distributions. Model results suggest methane hydrate cements unconsolidated sediment when forming in systems containing an abundant gas phase.

  5. Calcium ion binding to a soil fulvic acid using a donnan potential model

    USGS Publications Warehouse

    Marinsky, J.A.; Mathuthu, A.; Ephraim, J.H.; Reddy, M.M.

    1999-01-01

    Calcium ion binding to a soil fulvic acid (Armadale Bh Horizon) was evaluated over a range of calcium ion concentrations, from pH 3.8 to 7.3, using potentiometric titrations and calcium ion electrode measurements. Fulvic acid concentration was constant (100 milligrams per liter) and calcium ion concentration varied up to 8 X 10-4 moles per liter. Experiments discussed here included: (1) titrations of fulvic acid-calcium ion containing solutions with sodium hydroxide; and (2) titrations of fully neutralized fulvic acid with calcium chloride solutions. Apparent binding constants (expressed as the logarithm of the value, log ??app) vary with solution pH, calcium ion concentration, degree of acid dissociation, and ionic strength (from log ??app = 2.5 to 3.9) and are similar to those reported by others. Fulvic acid charge, and the associated Donnan Potential, influences calcium ion-fulvic acid ion pair formation. A Donnan Potential corrrection term allowed calculation of intrinsic calcium ion-fulvic acid binding constants. Intrinsic binding constants vary from 1.2 to 2.5 (the average value is about log??= 1.6) and are similar to, but somewhat higher than, stability constants for calcium ion-carboxylic acid monodentate complexes. ?? by Oldenbourg Wissenschaftsverlag, Mu??nchen.

  6. The effect of external sodium concentration on sodium–calcium exchange in frog olfactory receptor cells

    PubMed Central

    Antolin, Salome; Matthews, Hugh R

    2007-01-01

    During the response of vertebrate olfactory receptor cells to stimulation, Ca2+ enters the cilia via cyclic nucleotide-gated channels and is extruded by Na+–Ca2+ exchange. The rise in Ca2+ concentration opens a Ca2+-activated Cl? conductance which carries most of the inward receptor current. The dependence of Ca2+ extrusion upon external Na+ concentration was studied by using the falling phase of the Ca2+-activated Cl? current following a brief exposure to the phosphodiesterase inhibitor IBMX to monitor indirectly the decay in intraciliary Ca2+ concentration. External Na+ concentration was reduced by partial substitution with guanidinium, an ion which permeates the cyclic nucleotide-gated channel but does not support Na+–Ca2+ exchange. The time constant describing the decay in current following IBMX stimulation was surprisingly little affected by substitution of external Na+, being substantially retarded only when its concentration was reduced to a third or less of its normal value in Ringer solution. When the cilia were returned to Ringer solution after a period in reduced-Na+ solution, the time constant for the final decay of current was similar to that seen when returning immediately to IBMX-free Ringer solution. This observation suggests that Ca2+ extrusion via Na+–Ca2+ exchange dominates the falling phase of the response to IBMX, which can therefore be used to assess exchanger activity. Rate constants derived from the time constants for current decay at different external Na+ concentrations could be fitted by the Hill equation with a Kd of 54 ± 4 mm and Hill coefficient of 3.7 ± 0.4. The cooperativity of the dependence upon external Na+ concentration indicates that at least three Na+ ions enter for each exchanger cycle, while the high affinity for external Na+ contrasts with the photoreceptor and cardiac exchangers. The functional importance of this observation is that the relative insensitivity of the Na+–Ca2+ exchanger to external Na+ concentration allows normal response termination even following partial dilution or concentration of the olfactory mucus. PMID:17379630

  7. Control of ammonia toxicity to Hyalella azteca by sodium, potassium and pH

    Microsoft Academic Search

    Uwe Borgmann; Anne I. Borgmann

    1997-01-01

    The toxicity of ammonia to Hyalella azteca at constant pH in artificial media was controlled by sodium and potassium, and not by calcium, magnesium, or anions. Small increases in the LC50 for total ammonia (from 0.15 to 0.5 mM) occurred as sodium was increased from 0.1 to 1 mM and above, but major increases in the LC50 (to over 10

  8. Types of Gas Hydrates in Marine Environments and Their Thermodynamic Characteristics

    Microsoft Academic Search

    Duo-Fu Chen; Zheng Su; Lawrence M. Cathles

    2006-01-01

    The hydrates in marine environment can be grouped into two categories, diffusion gas hydrates and vent gas hydrates. The diffusion gas hydrates occur widely in an area where bottom simulation reflector (BSR) was re- corded in seismic profiles, and is a thermodynamic equilibrium system of hydrates and water with dissolved methane within gas hydrate stability zone (GHSZ). The hydrates are

  9. Distribution of near-surface gas hydrates and associated features on Hydrate Ridge, offshore Oregon

    NASA Astrophysics Data System (ADS)

    Klaucke, I.; Weinrebe, W.; Bohrmann, G.

    2003-04-01

    Detailed measurements of backscatter intensity of the seafloor on Hydrate Ridge (offshore Oregon) using 75 kHz sidescan sonar allowed the determination of the distribution of near-surface gas hydrates and associated features such as carbonate crusts and clam fields. The sidescan sonar data consist of seven parallel, N-S trending profiles of 1500 m swath width. They are processed with a pixel size of 0.75 m. The sidescan data are complemented by multibeam bathymetry data and echosounder profiles. Ground-truthing is possible through numerous video observations and short sediment cores. Carbonate crusts are easily recognised by high backscatter intensity while pure clam fields show lower backscatter than the surrounding seafloor. Near-surface gas hydrates are believed to be represented by irregular, patchy areas of high and low backscatter intensity. All these features are concentrated on local summits that appear to concentrate upward fluid flow. Hydrate Ridge also appears to be highly faulted and small, isolated manifestations of fluid venting are aligned along these faults. Carbonate crusts are the most prominent features of fluid venting with diameters of individual high backscatter patches on the order of several hundreds of metres. They seem to be more randomly distributed and are absent on the southern summit of Hydrate Ridge. This could reflect that prominent carbonate crusts are features of relict fluid venting sites. All these features related to gas hydrates and fluid venting are widespread on Hydrate Ridge. As a first rough estimate more than half of the surface of Hydrate Ridge shows features related to gas hydrates. This figure drops to around 10% away from the two summits of Hydrate Ridge. Knowing the extent of gas hydrate related facies it is possible to combine these data with measurements of gas hydrate content and fluid flux in order to derive regional reservoir estimates and flux rates.

  10. 21 CFR 184.1733 - Sodium benzoate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...as GRAS § 184.1733 Sodium benzoate. (a) Sodium benzoate is the chemical benzoate of soda (C7 ...produced by the neutralization of benzoic acid with sodium bicarbonate, sodium carbonate, or sodium hydroxide. The salt is...

  11. 21 CFR 184.1733 - Sodium benzoate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...as GRAS § 184.1733 Sodium benzoate. (a) Sodium benzoate is the chemical benzoate of soda (C7 ...produced by the neutralization of benzoic acid with sodium bicarbonate, sodium carbonate, or sodium hydroxide. The salt is...

  12. 21 CFR 184.1733 - Sodium benzoate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...as GRAS § 184.1733 Sodium benzoate. (a) Sodium benzoate is the chemical benzoate of soda (C7 ...produced by the neutralization of benzoic acid with sodium bicarbonate, sodium carbonate, or sodium hydroxide. The salt is...

  13. 21 CFR 184.1733 - Sodium benzoate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...as GRAS § 184.1733 Sodium benzoate. (a) Sodium benzoate is the chemical benzoate of soda (C7 ...produced by the neutralization of benzoic acid with sodium bicarbonate, sodium carbonate, or sodium hydroxide. The salt is...

  14. Hydration kinetics of phosphorus slag-cement paste

    Microsoft Academic Search

    Xia Chen; Kunhe Fang; Huaquan Yang; Hua Peng

    2011-01-01

    Hydration characteristics of Portland cement paste with phosphorus slag powder incorporated and hydration kinetics was investigated\\u000a with SEM, X-ray diffraction, DTA-TG and calorimeter II 80. Results showed that phosphorus slag powder could reduce total amount\\u000a of hydration products yet had little influence on the type of hydration products. The total amount of heat of hydration was\\u000a decreased by 49.11% and

  15. Physical properties of sediment containing methane gas hydrate

    USGS Publications Warehouse

    Winters, W.J.; Waite, W.F.; Mason, D.H.; Gilbert, L.Y.

    2005-01-01

    A study conducted by the US Geological Survey (USGS) on the formation, behavior, and properties of mixtures of gas hydrate and sediment is presented. The results show that the properties of host material influence the type and quantity of hydrates formed. The presence of hydrate during mechanical shear tests affects the measured sediment pore pressure. Sediment shear strength may be increased more than 500 percent by intact hydrate, but greatly weakened if the hydrate dissociates.

  16. Elemental Content of Calcium Oxalate Stones from a Canine Model of Urinary Stone Disease

    PubMed Central

    Killilea, David W.; Westropp, Jodi L.; Shiraki, Ryoji; Mellema, Matthew; Larsen, Jennifer; Kahn, Arnold J.; Kapahi, Pankaj; Chi, Thomas; Stoller, Marshall L.

    2015-01-01

    One of the most common types of urinary stones formed in humans and some other mammals is composed of calcium oxalate in ordered hydrated crystals. Many studies have reported a range of metals other than calcium in human stones, but few have looked at stones from animal models such as the dog. Therefore, we determined the elemental profile of canine calcium oxalate urinary stones and compared it to reported values from human stones. The content of 19 elements spanning 7-orders of magnitude was quantified in calcium oxalate stones from 53 dogs. The elemental profile of the canine stones was highly overlapping with human stones, indicating similar inorganic composition. Correlation and cluster analysis was then performed on the elemental profile from canine stones to evaluate associations between the elements and test for potential subgrouping based on elemental content. No correlations were observed with the most abundant metal calcium. However, magnesium and sulfur content correlated with the mineral hydration form, while phosphorous and zinc content correlated with the neuter status of the dog. Inter-elemental correlation analysis indicated strong associations between barium, phosphorous, and zinc content. Additionally, cluster analysis revealed subgroups within the stones that were also based primarily on barium, phosphorous, and zinc. These data support the use of the dog as a model to study the effects of trace metal homeostasis in urinary stone disease. PMID:26066810

  17. Elemental Content of Calcium Oxalate Stones from a Canine Model of Urinary Stone Disease.

    PubMed

    Killilea, David W; Westropp, Jodi L; Shiraki, Ryoji; Mellema, Matthew; Larsen, Jennifer; Kahn, Arnold J; Kapahi, Pankaj; Chi, Thomas; Stoller, Marshall L

    2015-01-01

    One of the most common types of urinary stones formed in humans and some other mammals is composed of calcium oxalate in ordered hydrated crystals. Many studies have reported a range of metals other than calcium in human stones, but few have looked at stones from animal models such as the dog. Therefore, we determined the elemental profile of canine calcium oxalate urinary stones and compared it to reported values from human stones. The content of 19 elements spanning 7-orders of magnitude was quantified in calcium oxalate stones from 53 dogs. The elemental profile of the canine stones was highly overlapping with human stones, indicating similar inorganic composition. Correlation and cluster analysis was then performed on the elemental profile from canine stones to evaluate associations between the elements and test for potential subgrouping based on elemental content. No correlations were observed with the most abundant metal calcium. However, magnesium and sulfur content correlated with the mineral hydration form, while phosphorous and zinc content correlated with the neuter status of the dog. Inter-elemental correlation analysis indicated strong associations between barium, phosphorous, and zinc content. Additionally, cluster analysis revealed subgroups within the stones that were also based primarily on barium, phosphorous, and zinc. These data support the use of the dog as a model to study the effects of trace metal homeostasis in urinary stone disease. PMID:26066810

  18. Influences of Dilute Organic Adsorbates on the Hydration of Low-Surface-Area Silicates.

    PubMed

    Sangodkar, Rahul P; Smith, Benjamin J; Gajan, David; Rossini, Aaron J; Roberts, Lawrence R; Funkhouser, Gary P; Lesage, Anne; Emsley, Lyndon; Chmelka, Bradley F

    2015-07-01

    Competitive adsorption of dilute quantities of certain organic molecules and water at silicate surfaces strongly influence the rates of silicate dissolution, hydration, and crystallization. Here, we determine the molecular-level structures, compositions, and site-specific interactions of adsorbed organic molecules at low absolute bulk concentrations on heterogeneous silicate particle surfaces at early stages of hydration. Specifically, dilute quantities (?0.1% by weight of solids) of the disaccharide sucrose or industrially important phosphonic acid species slow dramatically the hydration of low-surface-area (?1 m(2)/g) silicate particles. Here, the physicochemically distinct adsorption interactions of these organic species are established by using dynamic nuclear polarization (DNP) surface-enhanced solid-state NMR techniques. These measurements provide significantly improved signal sensitivity for near-surface species that is crucial for the detection and analysis of dilute adsorbed organic molecules and silicate species on low-surface-area particles, which until now have been infeasible to characterize. DNP-enhanced 2D (29)Si{(1)H}, (13)C{(1)H}, and (31)P{(1)H} heteronuclear correlation and 1D (29)Si{(13)C} rotational-echo double-resonance NMR measurements establish hydrogen-bond-mediated adsorption of sucrose at distinct nonhydrated and hydrated silicate surface sites and electrostatic interactions with surface Ca(2+) cations. By comparison, phosphonic acid molecules are found to adsorb electrostatically at or near cationic calcium surface sites to form Ca(2+)-phosphonate complexes. Although dilute quantities of both types of organic molecules effectively inhibit hydration, they do so by adsorbing in distinct ways that depend on their specific architectures and physicochemical interactions. The results demonstrate the feasibility of using DNP-enhanced NMR techniques to measure and assess dilute adsorbed molecules and their molecular interactions on low-surface-area materials, notably for compositions that are industrially relevant. PMID:26029958

  19. Phase equilibrium of gas hydrate: Implications for the formation of hydrate in the deep sea floor

    NASA Astrophysics Data System (ADS)

    Zatsepina, Olga Ye.; Buffett, Bruce A.

    We calculate the solubility of methane gas over a range of pressure and temperature. The gas is dissolved in liquid water, which coexists with free gas at high temperature or solid hydrate at low temperature and high pressure. We show that solubility is significantly altered by the presence or absence of the hydrate phase. When hydrate is absent at high temperatures, our calculations reproduce experimentally observed increases in solubility with decreasing temperature. When hydrate is present, however, we find that the gas solubility decreases sharply with decreasing temperature. Such an abrupt decrease in solubility permits hydrate to crystallize directly from the aqueous solution, without the need of any free gas. This result has important implications for the formation of gas hydrate in marine environments, where the gas supply may not be sufficient to provide free gas. We apply our calculations at typical pressure and temperature conditions in marine sediments to establish the gas concentration needed to stabilize hydrate. Estimates of the vertical distribution of hydrate in marine sediments and the rate of accumulation are obtained using simple models of hydrate formation.

  20. Effect of Ligand Structural Isomerism in Formation of Calcium Coordination Networks

    SciTech Connect

    Plonka A. M.; Parise J.; Banerjee, D.

    2012-03-28

    Using different structural isomers (2,5-; 2,4-; 2;6-; 3,4-; 3,5-) of pyridinedicarboxylic acid, nine calcium-based coordination networks were synthesized under hydro-/solvothermal conditions and/or were produced via solvent recrystallization of previously synthesized compounds. The coordination networks reported were characterized using single crystal X-ray diffraction and thermal methods. They show diverse structural topologies, depending on the ligand geometry and coordinated solvent molecules, with inorganic connectivity motifs ranging from isolated octahedra to infinite chains, layer and a three-dimensional dense framework. The as-synthesized and desolvated networks further show structural transformation to hydrated phases through dissolution/reformation pathways. The process is likely driven by the high hydration energy of the calcium metal center.