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1

21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

2

21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.  

Code of Federal Regulations, 2013 CFR

...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...

2013-04-01

3

THE SOLUBILITY OF CALCIUM CITRATE HYDRATE IN SODIUM PERCHLORATE SOLUTIONS  

Microsoft Academic Search

The solubility, at 25C, of calcium citrate, Ca3(C6H5O7)2. 4H2O, in NaClO4 solutions in the molality (m) range 03.5, has been determined by potentiometric titration with EDTA, using the Hg\\/Hg half-cell. The increase of solubility with m has been explained with the specific interaction theory by assuming, for Ca3(C6 H5 O7)2.4 H2 O(s) ?3Ca + 26H55O7 , log Ks0= ?17.81

Liberato Ciavatta; Gaetano De Tommaso; Mauro Iuliano

2001-01-01

4

Comparison of two hydrated sodium calcium aluminosilicate compounds to experimentally protect growing barrows from aflatoxicosis.  

PubMed

Two formulations of hydrated sodium calcium aluminosilicate (HSCAS-1 and HSCAS-3), anti-caking agents for mixed feed, were added to the diets of growing barrows and were evaluated for their potential to diminish the clinical signs of aflatoxicosis. The experimental design consisted of 8 barrows (2 replicates of 4 each/treatment) assigned to 1 of the following 6 treatment diets (total of 48): 1) 0 g of HSCAS-1 or HSCAS-3 and 0 mg of aflatoxin (AF)/kg of feed (control); 2) 5 g HSCAS-1/kg of feed; 3) 5 g HSCAS-3/kg of feed; 4) 3 mg AF/kg of feed; 5) 3 mg AF plus 5 g HSCAS-1/kg of feed; or 6) 3 mg AF plus 5 g HSCAS-3/kg of feed. Barrows were maintained in indoor concrete-floored pens, with feed and water available for 28 days (from 8 to 12 weeks of age). Barrows were observed twice daily and weighed weekly, and blood samples were collected at day 28 for hematologic, immunologic, and serum biochemical measurements. At the termination of the study, barrows were euthanized and necropsied. Barrow body weight gains were diminished, compared to those of controls, by consumption of AF alone and both of the AF plus HSCAS diets; however, the AF plus HSCAS-1 and AF plus HSCAS-3 barrow body weight gains were significantly greater (P < 0.05) than those of the AF-alone barrows.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8011787

Harvey, R B; Kubena, L F; Elissalde, M H; Corrier, D E; Phillips, T D

1994-01-01

5

Generalized structural description of calcium-sodium aluminosilicate hydrate gels: the cross-linked substituted tobermorite model.  

PubMed

Structural models for the primary strength and durability-giving reaction product in modern cements, a calcium (alumino)silicate hydrate gel, have previously been based solely on non-cross-linked tobermorite structures. However, recent experimental studies of laboratory-synthesized and alkali-activated slag (AAS) binders have indicated that the calcium-sodium aluminosilicate hydrate [C-(N)-A-S-H] gel formed in these systems can be significantly cross-linked. Here, we propose a model that describes the C-(N)-A-S-H gel as a mixture of cross-linked and non-cross-linked tobermorite-based structures (the cross-linked substituted tobermorite model, CSTM), which can more appropriately describe the spectroscopic and density information available for this material. Analysis of the phase assemblage and Al coordination environments of AAS binders shows that it is not possible to fully account for the chemistry of AAS by use of the assumption that all of the tetrahedral Al is present in a tobermorite-type C-(N)-A-S-H gel, due to the structural constraints of the gel. Application of the CSTM can for the first time reconcile this information, indicating the presence of an additional activation product that contains highly connected four-coordinated silicate and aluminate species. The CSTM therefore provides a more advanced description of the chemistry and structure of calcium-sodium aluminosilicate gel structures than that previously established in the literature. PMID:23534827

Myers, Rupert J; Bernal, Susan A; San Nicolas, Rackel; Provis, John L

2013-04-30

6

Comparison of hydrated sodium calcium aluminosilicate and yeast cell wall on counteracting aflatoxicosis in broiler chicks.  

PubMed

The objective of this research was to determine the efficacy of 2 types of adsorbents [hydrated sodium calcium aluminosilicates (HSCAS) vs. a combination of clay and yeast cell wall] in preventing aflatoxicosis in broilers. A total of 275 one-day-old birds were randomly divided into 11 treatments, with 5 replicate pens per treatment and 5 chicks per pen. The 11 treatments included 3 diets without any adsorbent containing either 0, 1, or 2 mg/kg of aflatoxin B1 (AFB1) plus 8 additional treatments employing 2 dietary levels of AFB1 (1 or 2 mg/kg), 2 different adsorbents [Solis (SO) and MTB-100 (MTB)], and 2 different levels of each absorbent (0.1 and 0.2%) in a 222 factorial arrangement. Solis is a mixture of different HSCAS and MTB is a combination of clay and yeast cell wall. Feed and water were provided ad libitum throughout the 21-d study period. Body weight gain and feed intake were depressed and relative liver weight was increased in chicks fed AFB1 compared with the positive control (P<0.05). Severe liver damage was observed in chicks fed 2 mg/kg of AFB1 with lesions consistent with aflatoxicosis, including fatty liver and vacuolar degeneration. Serum glucose, albumin, total protein, Ca, P, and alkaline phosphatase concentrations were reduced by AFB1 (P<0.05). The addition of either SO or MTB ameliorated the negative effects of 1 mg/kg of AFB1 on growth performance and liver damage (P<0.05). However, supplemental MTB failed to diminish the negative effects of 2 mg/kg of AFB1, whereas SO was more effective compared with MTB at 2 mg/kg of AFB1 (P<0.05). These data indicate that the HSCAS product effectively ameliorated the negative effect of AFB1 on growth performance and liver damage, whereas the yeast cell wall product was less effective especially at the higher AFB1 concentration. PMID:20852106

Zhao, J; Shirley, R B; Dibner, J D; Uraizee, F; Officer, M; Kitchell, M; Vazquez-Anon, M; Knight, C D

2010-10-01

7

Hydration modeling of calcium sulphates  

Microsoft Academic Search

The CEMHYD3D model has been extended at the University of Twente in the last ten years [1,2]. At present the cement hydration model is extended for the use of gypsum. Although gypsum was present in the model already, the model was not suitable for high contents of gypsum and did not include the transitions between the different calcium sulphate phases

Korte de A. C. J; H. J. H. Brouwers; Hashem Al-Mattarneh; Kamal N. Mustapha; Muhd Fadhil Nuruddin

2008-01-01

8

Hydration modelling of Calcium Sulphates  

Microsoft Academic Search

The CEMHYD3D model has been extended at the University of Twente in last ten years1,2. At present the cement hydration model is extended for the use of gypsum. Although gypsum was present in the model already, the model was not suitable for high contents of gypsum and did not include the transitions between the different calcium sulphate phases (anhydrite, hemihydrate

Korte de Arin; R. Eligehausen; C. Gehlen

2008-01-01

9

Comparison of the sequestering properties of yeast cell wall extract and hydrated sodium calcium aluminosilicate in three in vitro models accounting for the animal physiological bioavailability of zearalenone.  

PubMed

The sequestration/inactivation of the oestrogenic mycotoxin zearalenone (ZEA) by two adsorbents--yeast cell wall extract (YCW) and hydrated sodium calcium aluminosilicate (HSCAS)--was studied in three laboratory models: (1) an in vitro model was adapted from referenced methods to test for the sequestrant sorption capabilities under buffer conditions at two pH values using liquid chromatography coupled to a fluorescence detector for toxin quantification; (2) a second in vitro model was used to evaluate the sequestrant sorption stability according to pH variations and using H-labelled ZEA at low toxin concentration; and (3) an original, ex vivo Ussing chamber model was developed to further understand the transfer of ZEA through intestinal tissue and the impact of each sequestrant on the mycotoxin bioavailability of H-labelled ZEA. YCW was a more efficient ZEA adsorbent than HSCAS in all three models, except under very acidic conditions (pH 2.5 or 3.0). The Ussing chamber model offered a novel, ex vivo, alternative method for understanding the effect of sequestrant on the bioavailability of ZEA. The results showed that compared with HSCAS, YCW was more efficient in sequestering ZEA and that it reduced the accumulation of ZEA in the intestinal tissue by 40% (p < 0.001). PMID:23844575

Yiannikouris, A; Kettunen, H; Apajalahti, J; Pennala, E; Moran, C A

2013-01-01

10

Hydration of calcium sulfate hemihydrate (CaSO 4 {1}/{2}H 2O) into gypsum (CaSO 42H 2O). The influence of the sodium poly(acrylate)/surface interaction and molecular weight  

NASA Astrophysics Data System (ADS)

The retarding influence of sodium poly(acrylate) (PANa) on the hydration of calcium sulfate hemihydrate (CaSO 4 {1}/{2}H 2O) was investigated. This study reports the influence of sodium poly(acrylate) on hemihydrate dissolution, on homogenous and heterogeneous gypsum (CaSO 42H 2O) nucleation as well as on gypsum growth. It is shown that adsorption of PANa does not hinder the dissolution of hemihydrate in the present experimental conditions. The specific interaction of PANa with gypsum can explain the oriented growth of gypsum crystal. The gypsum growth is slowed down but cannot be blocked by the adsorption of PANa. On the other hand, PANa can block the heterogeneous and homogenous gypsum nucleation. As soon as a critical surface density of PANa onto the hemihydrate surface is reached, the heterogeneous gypsum nucleation is prevented and hemihydrate hydration is indefinitely blocked. The interaction between PANa and the hemihydrate surface is of prime importance to control hydration. Also, the influence of the molecular weight of PANa on homogenous nucleation has been investigated. The precipitation of calcium polyacrylate can explain the differences between the two molecular weights used (2100 and 20 000). This work leads to the conclusion that heterogeneous nucleation is the key process that controls hydration of a system in which hemihydrate dissolution, gypsum nucleation and growth are all occurring at the same time in a continuous manner.

Boisvert, Jean-Philippe; Domenech, Marc; Foissy, Alain; Persello, Jacques; Mutin, Jean-Claude

2000-12-01

11

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

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

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

2013-01-01

12

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

PubMed

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

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

2014-08-01

13

Hydration of calcium sulfoaluminate cements - Experimental findings and thermodynamic modelling  

SciTech Connect

Calcium sulfoaluminate cements (CSA) are a promising low-CO{sub 2} alternative to ordinary Portland cements and are as well of interest concerning their use as binder for waste encapsulation. In this study, the hydration of two CSA cements has been investigated experimentally and by thermodynamic modelling between 1 h and 28 days at w/c ratios of 0.72 and 0.80, respectively. The main hydration product of CSA is ettringite, which precipitates together with amorphous Al(OH){sub 3} until the calcium sulfate is consumed after around 1-2 days of hydration. Afterwards, monosulfate is formed. In the presence of belite, straetlingite occurs as an additional hydration product. The pore solution analysis reveals that straetlingite can bind a part of the potassium ions, which are released by the clinker minerals. The microstructure of both cements is quite dense even after 16 h of hydration, with not much pore space available at a sample age of 28 days. The pore solution of both cements is dominated during the first hours of hydration by potassium, sodium, calcium, aluminium and sulfate; the pH is around 10-11. When the calcium sulfate is depleted, the sulfate concentration drops by a factor of 10. This increases pH to around 12.5-12.8. Based on the experimental data, a thermodynamic hydration model for CSA cements based on cement composition, hydration kinetics of clinker phases and calculations of thermodynamic equilibria by geochemical speciation has been established. The modelled phase development with ongoing hydration agrees well with the experimental findings.

Winnefeld, Frank, E-mail: Frank.Winnefeld@empa.c [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Concrete and Construction Chemistry, Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Concrete and Construction Chemistry, Duebendorf (Switzerland)

2010-08-15

14

Hydration water and microstructure in calcium silicate and aluminate hydrates  

Microsoft Academic Search

Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C3S, C2S) and aluminates (C3A, C4AF) were studied by

Emiliano Fratini; Francesca Ridi; Sow-Hsin Chen; Piero Baglioni

2006-01-01

15

Nanostructure of calcium silicate hydrates in cements.  

PubMed

Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. PMID:20866975

Skinner, L B; Chae, S R; Benmore, C J; Wenk, H R; Monteiro, P J M

2010-05-14

16

Calcium Carbonate and Its Hydrates  

Microsoft Academic Search

This paper is concerned with observations on the preparation of phases which may exist in the system CaCO3-H2O in the presence of 'additives', with a qualitative explanation of the appearance of unstable phases under such conditions. It has been found that the tendency for metastable phases of calcium carbonate to be precipitated from aqueous solutions is increased not only by

R. Brooks; L. M. Clark; E. F. Thurston

1950-01-01

17

The interaction of calcium nitrate and a Class C fly ash during hydration  

SciTech Connect

Different analytical techniques were used to study the hydration of a Class C fly ash in the presence of various concentrations of calcium nitrate. Calcium nitrate was found to accelerate the hydration of calcium aluminate phases in relationship to dosage. Hydration mechanisms were modified resulting in altered products. The new products consisted of calcium aluminate hydrate and nitrate. Evidence suggested that the modified nitrate-hydrates competed with or inhibited the formation of calcium aluminate sulfates hydrates.

Hill, R. [Monex Resources, San Antonio, TX (United States)] [Monex Resources, San Antonio, TX (United States); Daugherty, K. [Univ. of North Texas, Denton, TX (United States)] [Univ. of North Texas, Denton, TX (United States)

1996-07-01

18

Influence of the calcium sulphate source on the hydration mechanism of Portland cementcalcium sulphoaluminate clinkercalcium sulphate binders  

Microsoft Academic Search

Two different binders composed of Portland cement, calcium sulphoaluminate clinker and calcium sulphate were studied from early hydration to 28days, one containing gypsum and one containing anhydrite at equimolar CaSO4 amount. Sodium gluconate was used as retarder to obtain a sufficient fluidity to cast the samples. Solids were analyzed by X-ray diffraction, scanning electron microscopy and thermogravimetric analysis and quantified

Laure Pelletier-Chaignat; Frank Winnefeld; Barbara Lothenbach; Gwenn Le Saout; Christian Jrg Mller; Charlotte Famy

2011-01-01

19

Hydration of Portland cement with additions of calcium sulfoaluminates  

SciTech Connect

The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.

Le Saout, Gwenn, E-mail: gwenn.le-saout@mines-ales.fr [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)] [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany)] [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan)] [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)] [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)

2013-01-15

20

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

NASA Astrophysics Data System (ADS)

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 90C; 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 80C 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 80C. Monosulfate, ettringite, gypsum and a hydrogarnet phase (Ca3Al2O66H2O) 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 60C 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 80C 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 50C. 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.

Clark, Boyd Arthur

21

The nanostructure of calcium silicate hydrate  

NASA Astrophysics Data System (ADS)

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)28H 2O] and jennite [Ca9(Si6O18)(OH) 68H2O]. 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.

Chen, Jeffrey J.

22

Problem of the hydration resistance of calcium oxide  

SciTech Connect

A study was made of the hydration tendencies of lime of varying degrees of sinterability. Some ways are indicated of increasing the hydration resistance of CaO. The investigation used pure grade calcium oxide. The lime was calcined at 1300, 1750, and 1950/sup 0/C with a soak of 2 h. To change the hydration resistance of the lime the additives Y/sub 2/O/sub 3/, MnO/sub 2/, and Cr/sub 2/O/sub 3/ were incorporated in the composition. Specimens prepared from lime with additions of yttrium oxide formed solid solutions on the basis of CaO during firing at 1950/sup 0/C. This contributed to an increase in the hydration resistance. Specimens prepared from CaO with additions of manganese and chromium oxides, fired at 1750/sup 0/C, also had a high hydration resistance.

Pitak, N.V.; Turchinova, L.N.; Gavrish, A.M.; Gul'ko, N.V.; Romanenko, S.N.

1988-09-01

23

An Evaluation of Hydrated Calcium Aluminate Compounds as Energy Storage Media.  

National Technical Information Service (NTIS)

Calcium aluminate hydrates and calcium aluminate hydrates containing other ions were investigated to determine the feasibility of their utilization as energy storage media. A series of these compounds were fabricated and analyzed for purity. The energy li...

J. B. Ings P. W. Brown

1982-01-01

24

Effect of sodium gluconate on the solubility of calcium lactate  

Microsoft Academic Search

Calcium and lactate are present in excess of their solubility in Cheddar cheese. Consequently, calcium lactate crystals (CLC) are a common defect in Cheddar cheese. A novel approach for preventing CLC is the addition of sodium gluconate. Sodium gluconate has the potential to increase the solubility of calcium and lactate by forming soluble complexes with calcium and lactate ions, and

C. Phadungath; L. E. Metzger

2011-01-01

25

Sodium phosphate-derived calcium phosphate cements  

SciTech Connect

Calcium phosphate cements (CPC) were synthesized by the acid-base reaction between sodium phosphate, NaH[sub 2]PO[sub 4] or -(-NaPO[sub 3]-)-[sub n], as the acid solution, and calcium aluminate cements (CAC) as the base reactant at 25 C. The extent of reactivity of -(-NaPO[sub 3]-)-[sub n] with CAC was much higher than that of NaH[sub 2]PO[sub 4], thereby resulting in a compressive strength of > 20 MPa. Sodium calcium orthophosphate (SCOP) salts as amorphous reaction products were responsible for the development of this strength. When this CPC specimen as exposed in an autoclave, in-situ amorphous [r arrow] crystal conversions, such as SCOP [r arrow] hydroxyapatite (HOAp), and Al[sub 2]O[sub 3] [center dot] xH[sub 2]O [r arrow] [gamma]-AlOOH, occurred at [approx] 100 C, while the rate of reaction of the residual CAC with the phosphate reactant was increasingly accelerated by hydrothermal catalysis. Based upon this information, the authors prepared lightweight CPC specimens by hydrothermally treating a low-density cement slurry (1.28 g/cc) consisting of CAC powder, -(-NaPO[sub 3]-)-[sub n] solution, and mullite-hollow microspheres. The characteristics of the autoclaved lightweight specimens were a compressive strength of > 9.0 MPa, water permeability of [approx] 5.0 [times] 10[sup [minus]3] milli darcy, and a low rate of alkali carbonation. The reasons for such a low carbonation rate reflected the presence of a minimum amount of residual CAC, in conjunction with the presence of HOAp and [gamma]-AlOOH phases that are unsusceptible to wet carbonation.

Sugama, T.; Carciello, N.R. (Brookhaven National Lab., Upton, NY (United States))

1995-01-01

26

Reactions of Calcium and Sodium during Combustion of Lignite  

Microsoft Academic Search

Calcium and sodium are abundant elements in low rank coals that can play a major role in ash fouling and slagging processes that result in reduced boiler efficiency during combustion. This paper presents an analytical investigation of the reactions of calcium and sodium during combustion of a lignite in two different combustion facilities. The principal analytical technique used in the

A. D. Shah; G. P. Huffman; F. E. Huggins; N. Shah; J. J. Helble; T. W. Peterson; J. Wendt; A. F. Sarofim

27

75 FR 39025 - Determination That ACTONEL (Risendronate Sodium) Tablets, 75 Milligrams, and ACTONEL WITH CALCIUM...  

Federal Register 2010, 2011, 2012, 2013

...Tablets, 75 Milligrams, and ACTONEL WITH CALCIUM (Risendronate Sodium and Calcium Carbonate (Copackaged)) Tablets, 35 Milligrams...Tablets, 75 milligrams (mg), and ACTONEL WITH CALCIUM (risendronate sodium and calcium...

2010-07-07

28

Hydration number of calcium palmitate LB film deposited on a piezoelectric quartz crystal plate  

Microsoft Academic Search

The calcium palmitate monolayer formed from palmitic acid on calcium-containing substrate can be examined regarding the study of hydration by applying the quartz crystal microbalance (QCM) technique. Monolayers of calcium palmitate were deposited on piezoelectric crystal plate by the Langmuir-Blodgett (LB) technique. Analysis of complete conversion to calcium palmitate was performed by identification of its infrared spectra. The estimation of

B. I. Seo; H. Lee; J. J. Chung; S. H. Cha; K. H. Lee; W. J. Seo; Y. Cho; H. B. Park; W. S. Kim

1998-01-01

29

The role of hydraulic binders on magnesia containing refractory castables: Calcium aluminate cement and hydratable alumina  

Microsoft Academic Search

Previous work by the authors has shown that the effects of calcium aluminate cement (CAC) and hydratable alumina (HA) can modify the magnesia hydration behavior in aqueous suspensions. As a consequence of these studies, the present paper highlights how varying the content of these binders can affect magnesia hydration in refractory castables using pH, apparent volumetric expansion, mechanical strength and

R. Salomo; V. C. Pandolfelli

2009-01-01

30

Order and disorder in calcium-silicate-hydrate  

NASA Astrophysics Data System (ADS)

Despite advances in the characterization and modeling of cement hydrates, the atomic order in Calcium-Silicate-Hydrate (C-S-H), the binding phase of cement, remains an open question. Indeed, in contrast to the former crystalline model, recent molecular models suggest that the nanoscale structure of C-S-H is amorphous. To elucidate this issue, we analyzed the structure of a realistic simulated model of C-S-H, and compared the latter to crystalline tobermorite, a natural analogue of C-S-H, and to an artificial ideal glass. The results clearly indicate that C-S-H appears as amorphous, when averaged on all atoms. However, an analysis of the order around each atomic species reveals that its structure shows an intermediate degree of order, retaining some characteristics of the crystal while acquiring an overall glass-like disorder. Thanks to a detailed quantification of order and disorder, we show that, while C-S-H retains some signatures of a tobermorite-like layered structure, hydrated species are completely amorphous.

Bauchy, M.; Qomi, M. J. Abdolhosseini; Ulm, F.-J.; Pellenq, R. J.-M.

2014-06-01

31

Order and disorder in calcium-silicate-hydrate.  

PubMed

Despite advances in the characterization and modeling of cement hydrates, the atomic order in Calcium-Silicate-Hydrate (C-S-H), the binding phase of cement, remains an open question. Indeed, in contrast to the former crystalline model, recent molecular models suggest that the nanoscale structure of C-S-H is amorphous. To elucidate this issue, we analyzed the structure of a realistic simulated model of C-S-H, and compared the latter to crystalline tobermorite, a natural analogue of C-S-H, and to an artificial ideal glass. The results clearly indicate that C-S-H appears as amorphous, when averaged on all atoms. However, an analysis of the order around each atomic species reveals that its structure shows an intermediate degree of order, retaining some characteristics of the crystal while acquiring an overall glass-like disorder. Thanks to a detailed quantification of order and disorder, we show that, while C-S-H retains some signatures of a tobermorite-like layered structure, hydrated species are completely amorphous. PMID:24908022

Bauchy, M; Qomi, M J Abdolhosseini; Ulm, F-J; Pellenq, R J-M

2014-06-01

32

Characterization of white Portland cement hydration and the CSH structure in the presence of sodium aluminate by 27Al and 29Si MAS NMR spectroscopy  

Microsoft Academic Search

The effects of hydrating a white Portland cement (wPc) in 0.30 and 0.50 M solutions of sodium aluminate (NaAlO2) at 5 and 20 C are investigated by 27Al and 29Si magic-angle spinning (MAS) NMR spectroscopy. It is demonstrated that NaAlO2 accelerates the hydration of alite and belite and results in calcium-silicate-hydrate (C-S-H) phases with longer average chain lengths of SiO4\\/AlO4

Morten Daugaard Andersen; Hans J. Jakobsen; Joergen Skibsted

2004-01-01

33

Hydration patterns and salting effects in sodium chloride solution  

NASA Astrophysics Data System (ADS)

The salting effects of 2M sodium chloride electrolyte are studied based on a series of model solutes with properties ranging from hydrophobic to hydrophilic. Generally, hydrophobic solutes will be salted out and hydrophilic solutes will be salted in by NaCl solution. The solvation free energy changes are highly correlated with Kirkwood-Buff integrals. The underlying mechanism resorts to the preferential binding of ions and water to solutes. Our results demonstrate that the salting effect not only depends on the salt's position in Hofmeister series, but also on the solutes' specifics. Taking the hydration free energies of solutes and ions as independent variables, a schematic diagram of salting effects is suggested. The resolved multifaceted salting effects rely on the sensitive balance of the tripartite interaction among solutes, ions, and water.

Li, Weifeng; Mu, Yuguang

2011-10-01

34

Hydration studies of calcium sulfoaluminate cements blended with fly ash  

SciTech Connect

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.

Garca-Mat, M.; De la Torre, A.G. [Departamento de Qumica Inorgnica, Cristalografa y Mineraloga, Universidad de Mlaga, 29071 Mlaga (Spain)] [Departamento de Qumica Inorgnica, Cristalografa y Mineraloga, Universidad de Mlaga, 29071 Mlaga (Spain); Len-Reina, L. [Servicios Centrales de Apoyo a la Investigacin, Universidad de Mlaga, 29071 Mlaga (Spain)] [Servicios Centrales de Apoyo a la Investigacin, Universidad de Mlaga, 29071 Mlaga (Spain); Aranda, M.A.G. [Departamento de Qumica Inorgnica, Cristalografa y Mineraloga, Universidad de Mlaga, 29071 Mlaga (Spain) [Departamento de Qumica Inorgnica, Cristalografa y Mineraloga, Universidad de Mlaga, 29071 Mlaga (Spain); CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); Santacruz, I., E-mail: isantacruz@uma.es [Departamento de Qumica Inorgnica, Cristalografa y Mineraloga, Universidad de Mlaga, 29071 Mlaga (Spain)

2013-12-15

35

Calcium aluminates hydration in presence of amorphous SiO 2 at temperatures below 90 C  

Microsoft Academic Search

The hydration behaviour of Ca3Al2O6, Ca12Al14O33 and CaAl2O4 with added amorphous silica at 40, 65 and 90C has been studied for periods ranging from 1 to 31 days. In hydrated samples crystalline phases like katoite (Ca3Al2(SiO4)3?x(OH)4x) and gibbsite, Al(OH)3, were identified, likewise amorphous phases like Al(OH)x, calcium silicate hydrates, CSH, and calcium aluminosilicate hydrates, CSAH, were identified. The stoichiometry of

J. M. Rivas Mercury; X. Turrillas; A. H. de. Aza; P. Pena

2006-01-01

36

Colchicine in avian sodium urate and calcium pyrophosphate microcrystal arthritis  

Microsoft Academic Search

The effect of single doses of colchicine on the acute arthritis elicited by the injection of microcrystalline sodium urate, calcium pyrophosphate or talcum into one intertarsal joint of chickens was functionally assessed. Colchicine was significantly active against the urate challenge. The arthritic inflammation induced by calcium pyrophosphate or talcum was reduced to a lesser degree. Colchicine may thus particularly affect

George L. Floersheim; Kay Brune; Karl Seiler

1973-01-01

37

Sodium-calcium exchangers contribute to the regulation of cytosolic calcium levels in mouse taste cells  

PubMed Central

Taste cells use multiple signalling mechanisms to generate unique calcium responses to distinct taste stimuli. Some taste stimuli activate G-protein coupled receptors (GPCRs) that cause calcium release from intracellular stores while other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). We recently demonstrated that a constitutive calcium influx exists in taste cells that is regulated by mitochondrial calcium transport and that the magnitude of this calcium influx correlates with the signalling mechanisms used by the taste cells. In this study, we used calcium imaging to determine that sodiumcalcium exchangers (NCXs) also routinely contribute to the regulation of basal cytosolic calcium and that their relative role correlates with the signalling mechanisms used by the taste cells. RT-PCR analysis revealed that multiple NCXs and sodiumcalciumpotassium exchangers (NCKXs) are expressed in taste cells. Thus, a dynamic relationship exists between calcium leak channels and calcium regulatory mechanisms in taste cells that functions to keep cytosolic calcium levels in the appropriate range for cell function.

Laskowski, Agnieszka I; Medler, Kathryn F

2009-01-01

38

Surface hydration of aqueous calcium minerals as studied by Fourier transform Raman and infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Rapid hydration reactions of several calcium minerals are studied using Fourier transform (FT) Raman and infrared (IR) spectroscopy. Oleate adsorption over aqueous synthetic fluorite, calcite and gypsum (pH 9) is investigated and adsorption mechanisms are discussed.

Holmgren, Allan; Wu, Liuming; Forsling, Willis

1994-10-01

39

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

Code of Federal Regulations, 2010 CFR

...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. 872.3490 Section...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. (a) Identification...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive is a device...

2010-04-01

40

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

Code of Federal Regulations, 2011 CFR

...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. 872.3490 Section...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. (a) Identification...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive is a device...

2011-04-01

41

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

Code of Federal Regulations, 2012 CFR

...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. 872.3490 Section...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. (a) Identification...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive is a device...

2012-04-01

42

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

...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. 872.3490 Section...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. (a) Identification...polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive is a device...

2014-04-01

43

A model for the microstructure of calcium silicate hydrate in cement paste  

Microsoft Academic Search

A model is proposed for the structure of calcium silicate hydrate (C-S-H) as it is formed during the hydration of Portland cement. One purpose of the model is to move toward an ability to evaluate the microstructure quantitatively, so that it can be related to properties on the one hand and processing on the other hand. It is a hypothesis

Hamlin M. Jennings

2000-01-01

44

Regulation of the sodium permeability of the luminal border of toad bladder by intracellular sodium and calcium: role of sodium-calcium exchange in the basolateral membrane  

Microsoft Academic Search

Sodium movement across the luminal membrane of the toad bladder is the rate-limiting step for active transepitheliaI transport. Recent studies suggest that changes in intracellular sodium regulate the Na permeability of the luminal border, either directly or indirectly via increases in cell calcium induced by the high intracellular sodium. To test these proposals, we measured Na movement across the luminal

HERBERT S. CHASE; QAIS AL-AWQATI

1981-01-01

45

Multi-scale hydration modeling of calcium sulphates  

Microsoft Academic Search

Computer models for cement hydration has been proven to be a useful tool for\\u000aunderstanding the chemistry of cement hydration, simulating the microstructure\\u000adevelopment of hydrating paste and predicting the properties of the hydration process \\/1\\/.\\u000aOne of these advanced models is CEMHYD3D, which is used and extended within the\\u000aUniversity of Twente for the last 12 years with pore

Korte de A. C. J; H. J. H. Brouwers; H. B. Fischer; K. A. Bode

2009-01-01

46

Electrochemical characteristics of uranium ions in calcium chloride hydrate melts  

NASA Astrophysics Data System (ADS)

Redox reactions of tetravalent uranium ion in calcium chloride hexahydrate CaCl26H2O melt ([CaCl2] = 6.9 M) were studied electrochemically and spectrophotometrically. Cyclic voltammograms in CaCl26H2O melt containing UCl4 were measured with a pyro-graphite carbon working electrode. A cathodic peak corresponding to the reduction of U4+ to U3+ was observed, and it was found to be controlled by the diffusion of U4+ in the melt. Although the concentration of H+ in the melt was negligible, the redox reaction of U4+ was observed without the disturbance of hydrolysis. The formal potential of the U4+|U3+ couple was determined to be -0.483 0.005 V vs. NHE. The diffusion coefficient of U4+ in CaCl26H2O melt was determined to be 1.5 10-7 cm2 s-1 at 300 K. The anodic peak in the voltammogram was attributable to the oxidation of U4+ to UO22+, which was identified by using a technique based on the combination of electrolysis and spectrophotometry. Influences of the water content on chemical status of uranium ions in CaCl2 hydrate melts were studied.

Uehara, A.; Fujii, T.; Nagai, T.; Shirai, O.; Sato, N.; Yamana, H.

2010-03-01

47

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

Code of Federal Regulations, 2010 CFR

...sodium stearate. Feed-grade calcium stearate and sodium stearate...conditions: (a) Feed-grade calcium stearate and sodium stearate are the calcium or sodium salts of a fatty...acids in aggregate do not exceed 35 percent by weight of the...

2009-04-01

48

Zeta-Potential Study of Calcium Silicate Hydrates Interacting with Alkaline Cations  

Microsoft Academic Search

An investigation into the interaction between alkaline cations and calcium silicate hydrates (CSH) was conducted by electrokinetic measurements, which provided information on the nature of the interface between the solid and its equilibrium solution. Calcium constitutes for the CSH surface a potential-determining cation. A model of the CSH surface could be proposed, accounting for the experimental evolution of the CSH

Hlne Viallis-Terrisse; Andr Nonat; Jean-Claude Petit

2001-01-01

49

Effect of sodium gluconate on the solubility of calcium lactate.  

PubMed

Calcium and lactate are present in excess of their solubility in Cheddar cheese. Consequently, calcium lactate crystals (CLC) are a common defect in Cheddar cheese. A novel approach for preventing CLC is the addition of sodium gluconate. Sodium gluconate has the potential to increase the solubility of calcium and lactate by forming soluble complexes with calcium and lactate ions, and preventing them from being available for the formation of CLC. The objective of this study was to determine if sodium gluconate could increase the solubility of calcium lactate (CaL(2)). Seven CaL(2) solutions (5.31% wt/wt) with 7 levels of sodium gluconate (0, 0.5, 1, 1.5, 2, 3, and 4% wt/wt) were made in triplicate. Solutions were stored at 7 C for 21 d, and were visually inspected for CLC formation. Subsequently, they were filtered to remove CLC and the supernatant was analyzed for lactic acid and gluconic acid by HPLC and for calcium by atomic absorption spectroscopy. The visual inspection demonstrated that CLC were formed in the solution with 0% gluconate after the first day of storage and CLC continued to accumulate over time. A minute amount of CLC was also visible in the solution with 0.5% gluconate after 21 d of storage, whereas CLC were not visible in the other solutions. The HPLC results indicated a higher concentration of calcium and lactic acid in the filtrate from the solutions containing added gluconate. Thus, sodium gluconate can increase the solubility of CaL(2). PMID:21943735

Phadungath, C; Metzger, L E

2011-10-01

50

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

Code of Federal Regulations, 2013 CFR

...Feed-grade calcium stearate and sodium stearate are the calcium or sodium salts of a fatty acid mixture that is predominately stearic acid. Associated fatty acids, including palmitic acid and minor amounts of lauric, myristic, pentadecanoic,...

2013-04-01

51

Determination of Nitrogen, Sulphur, Phosphorus, Potassium, Sodium, Calcium, and Magnesium in Plant Material by Automatic Analysis.  

National Technical Information Service (NTIS)

Methods are proposed for the rapid determination of nitrogen, sulphur, phosphorus, potassium, sodium, calcium, and magnesium in plant material by automated chemical analysis. Phosphorus, potassium, calcium, magnesium, and sodium are determined in nitric-p...

C. H. Williams J. R. Twine

1967-01-01

52

Enhanced growth of methanepropane clathrate hydrate crystals with sodium dodecyl sulfate, sodium tetradecyl sulfate, and sodium hexadecyl sulfate surfactants  

Microsoft Academic Search

In the present study the effect of three commercially available anionic surfactants on the hydrate growth from a gas mixture of 90.5mol% methane\\/9.5mol% propane mixture was investigated. The surfactants used were sodium dodecyl sulfate (SDS), sodium tetradecyl sulfate (STS), and sodium hexadecyl sulfate (SHS). The morphology of the growing crystals and the gas consumption were observed during the experiments. The

Jeffry Yoslim; Praveen Linga; Peter Englezos

2010-01-01

53

Accelerating effects of colloidal nano-silica for beneficial calciumsilicatehydrate formation in cement  

Microsoft Academic Search

The hydration process of Ca3SiO5 (C3S) cement is investigated, and accelerating effects of adding colloidal silica (CS) are established. CS accelerates dissolution of the C3S phase, and renders a more rapid formation of the calciumsilicatehydrate (CSH) binding phase. The role of water is demonstrated. Water evaporation correlates with the appearance of a sharp IR band at 3650 cm?1 signifying non-hydrogen

J. Bjornstrom; A. Martinelli; A. Matic; L. Borjesson; I. Panas

2004-01-01

54

The microstructure of the hydration products of tri-calcium aluminate in the presence of gypsum  

Microsoft Academic Search

The hydration of tri-calcium aluminate in the presence of gypsum has been examined by electron optical methods as a function of pH and hydration time. The location of the alumino-sulphate phase has been related to the solubility of aluminate ions from the precursive platelet phase. At pH ~ 11.5 the alumino-sulphate precipitate is crystalline and precipitates from solution. When first

C. J. Hampson; J. E. Bailey

1983-01-01

55

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

SciTech Connect

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.

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

56

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

SciTech Connect

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.

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

1993-12-01

57

Chemical and physical effects of sodium lignosulfonate superplasticizer on the hydration of portland cement and solidification\\/stabilization consequences  

Microsoft Academic Search

The effects of sodium lignosulfonate superplasticizer on the hydration of Portland cement Type V have been investigated by XRD and FTIR techniques. The results of these studies indicate that the superplasticizer inhibits the hydration reaction as demonstrated by the reduced formation of Ca(OH)2 as well as a lower degree of polymerization of the silicate anions. The hydration reaction seems to

M. Yousuf; A. Mollah; Padmavathy Palta; Thomas R. Hess; Rajan K. Vempati; David L. Cocke

1995-01-01

58

Oxidative dimerization of methane over sodium-promoted calcium oxide  

Microsoft Academic Search

Sodium-promoted calcium oxides are active and selective catalysts for the partial oxidation of methane to ethane and ethylene using molecular oxygen as an oxidant. In a conventional fixed-bed flow reactor, operating at atmospheric pressure, a 45% C (sum of ethane and ethylene) selectivity was achieved at a 33% methane conversion over 2.0 g of 15 wt% Na\\/CaO catalyst at 725°C

C. Lin; J. Wang; J. H. Lunsford

1988-01-01

59

Accelerated growth of calcium silicate hydrates: Experiments and simulations  

SciTech Connect

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.

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

2011-12-15

60

Morphological forms of tobermorite in hydrothermally treated calcium silicate hydrate gels  

Microsoft Academic Search

The morphology of the calcium silicate hydrate phase, tobermorite, generally thought to be the bonding phase in ordinary portland cement, was studied. Tobermorite was hydrothermally synthesized at pH 12.6 at 150 C. The powder was characterized by XRD and SEM analysis. Modeling of the morphology was performed using the SHAPE and ATOMS programs. Two morphologies were produced: fibers and platelets.

Nelson S. Bell; Sridhar Venigalla; Petra M. Gill; James H. Adair

1996-01-01

61

On the structure of some precipitated calcium alumino-sulphate hydrates  

Microsoft Academic Search

The chemistry of the calcium alumino-sulphate hydrates has been reassessed using the methods developed in a previous paper [10]. Ettringite does not have a constant solubility product. The rise in the ionic activity product of solutions in equilibrium with ettringite as a function of pH and sulphate activity is attributed to disordering of the crystal structure. This is due to

C. J. Hampsoim; J. E. Bailey

1982-01-01

62

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

Microsoft Academic Search

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

Jacob Lemann; Richard W Gray; Joan A Pleuss

1989-01-01

63

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

PubMed Central

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 have shown conflicting results regarding the protective effect of sodium bicarbonate. The objective of this study was to assess the effectiveness of normal saline versus sodium bicarbonate for prevention of contrast-induced nephropathy. Methods The study searched MEDLINE, EMBASE, Cochrane databases, International Pharmaceutical Abstracts database, ISI Web of Science (until 15 December 2008), and conference proceedings for randomized controlled trials that compared normal saline with sodium bicarbonate-based hydration regimen regarding contrast-induced nephropathy. Random-effects models were used to calculate summary odds ratios. Results A total of 17 trials including 2,633 subjects were pooled. Pre-procedural hydration with sodium bicarbonate was associated with a significant decrease in the rate of contrast-induced nephropathy (odds ratios 0.52; 95% confidence interval 0.340.80, P = 0.003). Number needed to treat to prevent one case of contrast-induced nephropathy was 16 (95% confidence interval 1034). No significant differences in the rates of post-procedure hemodialysis (P = 0.20) or death (P = 0.53) was observed. Conclusion Sodium bicarbonate-based hydration was found to be superior to normal saline in prevention of contrast-induced nephropathy in this updated meta-analysis.

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

2009-01-01

64

Influence of calcium ions on the crystallization of sodium bicarbonate  

NASA Astrophysics Data System (ADS)

In industrial crystallization of sodium bicarbonate (sodium hydrogenocarbonate), the presence of calcium ions in solutions is unavoidable due to the production process. The understanding of the Ca 2+ role in NaHCO 3 crystallization would be helpful for improving the quality of the final products. The influence of calcium ions on NaHCO 3 crystallization was investigated in a 5-l mixed suspension mixed product removal crystallizer under controlled conditions. A density meter was used for continuous supersaturation monitoring. After a steady state had been reached, different CaCl 2 amounts were added at a constant flow rate. It was found that limited calcium ion levels in the system reduce drastically the nucleation frequency of NaHCO 3 and has a limited influence on crystal growth rate. The supersaturation measurements and other methods confirmed this phenomenon. The relationship between the Ca 2+ influence on NaHCO 3 crystallization, the calcium carbonate solubility and its metastable zone in concentrated NaHCO 3 solution was established. In fact, Ca 2+ has a maximum effect on NaHCO 3 crystallization kinetics when the saturation of calcium carbonate in NaHCO 3 solution has been reached, and the effect is constant in the metastable zone. The excess of Ca 2+ precipitates in NaHCO 3 solution as CaCO 3, as observed by energy dispersive X-ray and X-ray diffraction. This explained why an increasing Ca 2+ concentration in the solution has a limited influence on NaHCO 3 crystal size distribution and habit, but decreases the crystal purity. It is also confirmed that an impurity as Ca 2+ has no influence on the equilibrium NaHCO 3-Na 2CO 3.

Zhu, Yi; Demilie, Paul; Davoine, Perrine; Cartage, Thierry; Delplancke-Ogletree, Marie-Paule

2005-02-01

65

Synaptosomal calcium influx is activated by sodium fluoride  

SciTech Connect

Neuronal calcium channels can be modulated by changes in membrane potential or by activation of channel-associated receptors. The latter may be modulated by guanine nucleotide binding proteins. NaF, which activates guanine nucleotide binding proteins, caused a large stimulation of /sup 45/Ca/sup 2 +/ uptake by synaptosomes prepared from rat brain. Stimulation of /sup 45/Ca/sup 2 +/ influx by NaF (i) was apparent in media containing either 5 mM-K+ or 50 mM-K+, (ii) was slower than the fast-phase of voltage-dependent /sup 45/Ca/sup 2 +/ influx but continued for a longer period of time than did depolarization-induced /sup 45/Ca/sup 2 +/ influx, and (iii) was not mimicked or modified by a number of drugs, including ouabain, dinitrophenol, sodium azide or sodium vanadate. These results are consistent with the hypothesis that NaF activates a guanine nucleotide binding protein associated with receptor-coupled calcium channels, resulting in stimulation of calcium influx.

Jope, R.S.; Lally, K.M.

1988-03-15

66

Hydration and strength development of binder based on high-calcium oil shale fly ash  

SciTech Connect

The properties of high-calcium oil shale fly ash and low-calcium coal fly ash, which are produced in Israeli power stations, were investigated. High-calcium oil shale fly ash was found to contain a great amount of CaO{sub free} and SO{sub 3} in the form of lime and anhydrite. Mixtures of high-calcium oil shale fly ash and low-calcium coal fly ash, termed fly ash binder, were shown to cure and have improved strength. The influence of the composition and curing conditions on the compressive strength of fly ash binders was examined. The microstructure and the composition of fly ash binder after curing and long-term exposure in moist air, water and open air conditions were studied. It was determined that ettringite is the main variable in the strength and durability of cured systems. The positive effect of calcium silicate hydrates, CSH, which are formed by interaction of high-calcium oil shale fly ash and low-calcium coal fly ash components, on the carbonation and dehydration resistance of fly ash binder in open air is pronounced. It was concluded that high-calcium oil shale fly ash with high CaO{sub free} and SO{sub 3} content can be used as a binder for building products.

Freidin, C. [Ben-Gurion Univ. of the Negev, Sede-Boqer (Israel)] [Ben-Gurion Univ. of the Negev, Sede-Boqer (Israel)

1998-06-01

67

Crystal chemistry and structure refinement of five hydrated calcium borates  

USGS Publications Warehouse

The crystal structures of the five known members of the series Ca2B6O11??xH2O (x = 1, 5, 5, 7, 9, and 13) have been refined by full-matrix least-squares techniques, yielding bond distances and angles with standard errors of less than 0??01 A?? and 0??5??, respectively. The results illustrate the crystal chemical principles that govern the structures of hydrated borate compounds. The importance of hydrogen bonding in the ferroelectric transition of colemanite is confirmed by more accurate proton assignments. ?? 1964.

Clark, J. R.; Appleman, D. E.; Christ, C. L.

1964-01-01

68

Effect of Lime on Hydration of Pastes Containing Gypsum and Calcium Aluminates or Calcium Sulfoaluminate.  

National Technical Information Service (NTIS)

Chemical reactions responsible for ettringite formation in the commercial expansive cements are reviewed. X-ray diffraction analyses of the hydrated expansive compounds showed that in the presence of Ca(OH)2 and CaSO4 the tricalcium aluminate hydrated ver...

P. K. Mehta

1973-01-01

69

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

PubMed

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

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

2014-02-28

70

Calcium effect on the solubility of sodium dodecyl sulfate in sodium chloride solutions  

SciTech Connect

Interactions between calcium ions and anionic surfactants have recently attracted increased interest, particularly because of the development of enhanced oil recovery through the use of micellar solutions. The brine in crude oil reservoirs always contains a certain amount of polyvalent ions, especially calcium ions, which have pronounced effects on the properties of micellar solutions, varying with electrolyte concentration and surfactant type. To date, the surfactants most often used are anionic. Precipitation of anionic surfactants with calcium ions was investigated. It was found that surfactant precipitation is governed by a given mechanism when the supernatant liquid is a micellar solution, and by another when it is not. This work discusses the results of a series of experiments which indicate that this difference is a function of sodium chloride concentration. 10 references.

Baviere, M.; Bazin, B.; Aude, R.

1983-04-01

71

Modelling the effects of salt solutions on the hydration of calcium ions.  

PubMed

Classical molecular dynamics simulations of several aqueous alkali halide salt solutions have been used to determine the effect of electrolytes on the structure of water and the hydration properties of calcium ions. Compared with the simulations of Ca(2+) ions in pure liquid water, the frequency of water exchange in the first hydration shell of calcium, which is a fundamental process in controlling the reactivity of calcium(ii) aqua-ions, is drastically reduced in the presence of other electrolytes in solution. The strong stabilization of the hydration shell of Ca(2+) occurs not only when the halide anions are directly coordinated to calcium, but also when the alkali and halide ions are placed at or outside the second coordination shell of Ca(2+), suggesting that the reactivity of the first solvation shell of the calcium ion can be influenced by the specific affinity of other ions in solution for the water molecules coordinated to Ca(2+). Analysis of the hydrogen-bonded structure of water in the vicinity of the calcium ion shows that the average number of hydrogen bonds per water molecules, which is 1.8 in pure liquid water, decreases as the concentration of alkali-halide salts in solution increases, and that the temporal fluctuations of hydrogen bonds are significantly larger than those obtained for Ca(2+) in pure liquid water. This effect has been explained in terms of the dynamics of reorganization of the O-HX(-) (X = F, Cl and Br) hydrogen bond. This work shows the importance of solution composition in determining the hydrogen-bonding network and ligand-exchange dynamics around metal ions, both in solution and at the mineral-water interfaces, which in turn has implications for interactions occurring at the mineral-water interface, ultimately controlling the mobilization of ions in the environment as well as in industrial processes. PMID:24643252

Di Tommaso, Devis; Ruiz-Agudo, Encarnacin; de Leeuw, Nora H; Putnis, Andrew; Putnis, Christine V

2014-05-01

72

Caesium immobilization in hydrated calcium-silicate-aluminate systems  

SciTech Connect

A special field of application of cementitious materials in using cements for immobilization of low and medium level radioactive wastes. Clarification of mechanisms of binding is complicated by the multicomponent nature of the solidifying matrix. In the present work, interest is turned to one of the most difficult to confine, long half-life isotopes, the caesium isotope. The cement matrix for solidification of the radioactive waste can be considered, with simplification, as a CaO-SiO{sub 2}-Al{sub 2}O{sub 3}-H{sub 2}O system. The various compositions of hydrated cementitious assemblages were investigated with respect to their Cs sorption by measuring the Cs distribution ratios (R{sub d}) therein. Trends in sorption properties were detected, and the section of the ternary phase diagram with the best performance was identified.

Bagosi, S.; Csetenyi, L.J. [Univ. of Veszprem (Hungary). Dept. of Silicate and Materials Engineering] [Univ. of Veszprem (Hungary). Dept. of Silicate and Materials Engineering

1998-12-01

73

Amelioration of Cadmium Polluted Paddy Soils by Porous Hydrated Calcium Silicate  

Microsoft Academic Search

Porous hydrated calcium silicate (PS) is a by-product of autoclave light weight concrete and is being used as a silicon fertilizer\\u000a in Japan. The impacts of this amendment on the yield and cadmium content of rice (Orzya sativa L. var. Kokoromachi), soil pH and the extractability of soil cadmium assessed by 1M NH4OAc were compared with those of silica gel

Xiu-Lan Zhao; Saigusa Masaihiko

2007-01-01

74

Preparation, characterization and cytocompatibility of bioactive coatings on porous calcium-silicate-hydrate scaffolds  

Microsoft Academic Search

The major goal of this research was to investigate and characterize the deposition of a biomimetic apatite-like coating onto the surface of 3D porous calcium-silicate-hydrate scaffolds with suitable bioactivity for potential application in bone tissue engineering. Basically, Portland cement, water, sand and lime were mixed for preparing the slurry which was poured into molds, and fine aluminum powder was added

Alexandra A. P. Mansur; Herman S. Mansur

2010-01-01

75

A model for two types of calcium silicate hydrate in the microstructure of Portland cement pastes  

Microsoft Academic Search

A new physical basis for a previously published model for the structure of calcium silicate hydrate (C-S-H) as measured by nitrogen sorption is described. This refined model provides a method of predicting the density, the nitrogen accessible gel porosity, and associated surface area of C-S-H in Portland cement pastes. The basis for the model is that C-S-H forms as one

Paul D Tennis; Hamlin M Jennings

2000-01-01

76

Morphological forms of tobermorite in hydrothermally treated calcium silicate hydrate gels  

SciTech Connect

The morphology of the calcium silicate hydrate phase, tobermorite, generally thought to be the bonding phase in ordinary portland cement, was studied. Tobermorite was hydrothermally synthesized at pH 12.6 at 150 C. The powder was characterized by XRD and SEM analysis. Modeling of the morphology was performed using the SHAPE and ATOMS programs. Two morphologies were produced: fibers and platelets. Computer calculations of equilibrium particle shape suggest that growth occurs on the (110)-type planes for both morphologies.

Bell, N.S.; Venigalla, S. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Gill, P.M. [Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.; Adair, J.H. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering]|[Pennsylvania State Univ., University Park, PA (United States). Materials Research Lab.

1996-08-01

77

Early Strength Development and Hydration of Ordinary Portland Cement\\/Calcium Aluminate Cement Pastes  

Microsoft Academic Search

The early strength development of ordinary Portland cement (OPC)\\/calcium aluminate cement (CAC) pastes (92.5\\/7.5, 80\\/20, and 20\\/80) was studied. Conduction calorimetry, X-ray diffraction, and scanning electron microscopy methods were used to monitor the heat evolution and microstructural changes of these pastes. It is apparent that ettringite formation contributes to the early set strength in the 80\\/20 paste. The OPC hydration

Ping Gu; James J Beaudoin; Edmond G Quinn; Robert E Myers

1997-01-01

78

Application of X-ray computed tomography to characterise the early hydration of calcium aluminate cement  

Microsoft Academic Search

Techniques that monitor in situ the setting and hardening of calcium aluminate cements (CACs) are of interest to the engineering community. This paper focuses on one non-destructive technique, X-ray computed tomography (CT). The early hydration of the cement can be followed from a few minutes to a few hours after mixing. This technique is based on both X-ray absorption measurements

T. J Chotard; M. P Boncoeur-Martel; A Smith; J. P Dupuy; C Gault

2003-01-01

79

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

Microsoft Academic Search

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 wastecement 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 070 days. A physical model was applied to determine

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

2004-01-01

80

The active phase in sodium-doped calcium oxide catalysts for oxidative coupling of methane  

SciTech Connect

The reactivity of pure and sodium-promoted calcium catalysts toward the oxidative coupling of methane at 640{degree}C has been investigated. While the pure calcium oxide was essentially a combustion catalyst, sodium-promoted calcium oxide exhibited significant C{sub 2} productivity. Study of the deactivation of both pure and promoted catalysts demonstrated that the presence of calcium oxide was necessary for both catalysts to be active. This observation, combined with the effects of sodium doping on C{sub 2} selectivity, suggests that the active phase on Na/CaO catalysts toward C{sub 2} formation consists of sodium species associated with calcium oxide. This active phase was destroyed when calcium oxide was converted into calcium carbonate under reaction conditions.

Peng, X.D.; Stair, P.C. (Northwestern Univ., Evanston, IL (USA))

1991-03-01

81

Effects of Sivelestat Sodium Hydrate for Acute Lung Injury Complicated by Stroke  

Microsoft Academic Search

Sivelestat sodium hydrate(SSH) a selective neutrophil elastase inhibitor is effective in treating acute lung injury(ALI)or acute respiratory distress syndrome(ARDS)associated with systemic inflammatory response syndrome(SIRS) .?SSH was administered to 1 4 patients (11 males and 3 femal es ranging from 3 4 to 87 years of age)who were admitted between 2 0 0 2 and 2 0 0 8 due to

Naoki WAKUTA; Mitsutoshi IWAASA; Tooru INOUE; Taisuke KITAMURA; Hiroyasu ISHIKURA

2009-01-01

82

Duodenal calcium-binding-protein (CaBP) in the sodium deficient growing rat  

Microsoft Academic Search

ConclusionsSodium deficiency imposed for one week on growing rats with adequate vitamin D and calcium intake led to:a decrease of fractional\\u000a calcium absorption,an increase of intracellular calcium from duodenal mucosa (S100),the maintenance of peak B (CaBP) and an enhancement of its calcium binding activity.\\u000a \\u000a According to our results, the increase of calcium binding activity could be interpreted as one physiologic

M. Thomasset; P. Cuisinier-Gleizes; H. Mathieu

1975-01-01

83

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

USGS Publications Warehouse

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.

Erd, R. C.; Ohashi, Y.

1984-01-01

84

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

NASA Astrophysics Data System (ADS)

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 ?, the self-diffusion constant D, the average translational relaxation time , and the temperature dependence of confinement radius ? extracted from the elastic fraction of immobile water molecules p(Q) were obtained from the analyses of the low-Q spectra according to the relaxing cage model. Measurements were made using C-S-H of three different water contents, 10%, 17%, and 30%. Among the three samples of C-S-H gel with different water contents, the values of ? decrease with increasing water contents, while ? increases. The values of D and are insensitive to temperature for the two lower water contents, as opposed to the 30% case where a slight variation is observed. The trend for violation of the Stokes-Einstein relation is only visible in the case of 30% water content.

Li, Hua; Fratini, Emiliano; Chiang, Wei-Shan; Baglioni, Piero; Mamontov, Eugene; Chen, Sow-Hsin

2012-12-01

85

Effect of Sodium Silicate on Flocculation of Hematite with Starch in the Presence of Calcium  

Microsoft Academic Search

Sodium silicate is used as a dispersant in the selective flocculation of iron ores with starch as the polymeric floccullant. The mechanism of its dispersive effect on quartz has been reported to be related to its ability to remove coagulants, such as calcium and magnesium ions, from the process water. The interaction between iron oxides and calcium and sodium silicate,

Ali I. Arol; Iwao Iwasaki

2003-01-01

86

Determination of calcium in sodium by vacuum distillation-atomic absorption spectrophotometry.  

National Technical Information Service (NTIS)

A method for determing calcium in sodium at 2 ppm or more is described. The matrix sodium was removed by vacuum distillation at 360 deg C and 5 x 10(sup -3) Pa. The calcium in the residue was determined by atomic absorption spectrophotometry. The recovery...

X. Wen S. Su S. Sun J. Liu D. Ding

1990-01-01

87

Calcium absorption by fish intestine: The involvement of ATP-and sodium-dependent calcium extrusion mechanisms  

Microsoft Academic Search

Summary Measurements of unidirectional calcium fluxes in stripped intestinal epithelium of the tilapia,Oreochromis mossambicus, in the presence of ouabain or in the absence of sodium indicated that calcium absorption via the fish intestine is sodium dependent. Active Ca2+ transport mechanisms in the enterocyte plasma membrane were analyzed. The maximum capacity of the ATP-dependent Ca2+ pump (Vm:0.63 nmolmin-1 mg-1,Km: 27nm Ca2+)

Gert Flik; Theo J. M. Schoenmakers; Jack A. Groot; Carel H. van Os; Sjoerd E. Wendelaar Bonga

1990-01-01

88

Prediction of Incompatibility of Ceftriaxone Sodium with Calcium Ions Using the Ionic Product  

Microsoft Academic Search

The purpose of this study was to evaluate the incompatibility of ceftriaxone sodium with calcium-containing products using the ionic product of precipitation, and the measurement of insoluble microparticles using a light obscura- tion particle counter. Appropriate volumes of 2% (w\\/v) calcium chloride solution were added to 0.4? 2m g\\/ml ceftriaxone isotonic sodium chloride solution, to make solutions with anal calcium

Yuka NAKAI; Emi TOKUYAMA; Miyako YOSHIDA; Takahiro UCHIDA

2010-01-01

89

Efficacy of calcium sodium phosphosilicate in managing dentinal hypersensitivity.  

PubMed

A large number of home use products have been tested and used for managing dentinal hypersensitivity. This eight-week clinical trial compared the temporal efficacy of a commercially available toothpaste containing calcium sodium phosphosilicate to that of a toothpaste containing potassium nitrate. For this study, 20 subjects (age 18 - 65) were screened using a visual analog scale (VAS) for sensitivity to a cold stimulus. Baseline VAS sensitivity scores to tactile stimulus were recorded for a minimum of two teeth per patient. Dentifrices were prescribed for all patients and sensitivity scores were re-evaluated at two, four, and eight weeks. Though both groups showed significant reductions in sensitivity scores, only at eight weeks was there a marginally significant difference (p = 0.0551) in sensitivity scores between the test group and the positive control group. PMID:23032238

Surve, Sai M; Acharya, Anirudh B; Shetty, Ananya; Thakur, Srinath L

2012-01-01

90

Relations for the determination of the polymorphic composition of calcium carbonate precipitated in saturated sodium chloride solutions  

Microsoft Academic Search

The purification of concentrated sodium chloride solutions from calcium and magnesium ions is realized by precipitating them in the form of calcium carbonate and magnesium hydroxide using a reagent solution composed of sodium carbonate and sodium hydroxide. The functioning of the industrial process depends on the polymorphic composition of the precipitated calcium carbonate. The classical experimental design method is used

C. Berger; A. Dandeu; C. Carteret; B. Humbert; H. Muhr; E. Plasari; J. M. Bossoutrot

91

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

SciTech Connect

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.

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

92

Preparation and properties of calcium silicate hydrate-poly(vinyl alcohol) nanocomposite materials  

Microsoft Academic Search

SummaryA series of calcium silicate hydrate (C-S-H)-polymer nanocomposite (C-S-HPN) materials were prepared by incorporating poly(vinyl\\u000a alcohol) (PVA) into the inorganic layers of C-S-H during precipitation of quasicrystalline C-S-H from aqueous solution. The\\u000a as synthesized C-S-HPN materials were characterized by Fourier-transform infrared photoacoustic (FTIRPAS) spectroscopy, X-ray\\u000a diffraction (XRD), scanning electron microscopy\\/energy dispersed spectroscopy (SEM\\/EDS), thermogravimetric analysis (TG),\\u000a differential thermogravimetry (DTG) and

S. C. Mojumdar; L. Raki

2005-01-01

93

Integrin-mediated Membrane Blebbing Is Dependent on Sodium-Proton Exchanger 1 and Sodium-Calcium Exchanger 1 Activity*  

PubMed Central

Integrin signaling and membrane blebbing modulate cell adhesion, spreading, and migration. However, the relationship between integrin signaling and membrane blebbing is unclear. Here, we show that an integrin-ligand interaction induces both membrane blebbing and changes in membrane permeability. Sodium-proton exchanger 1 (NHE1) and sodium-calcium exchanger 1 (NCX1) are membrane proteins located on the bleb membrane. Inhibition of NHE1 disrupts membrane blebbing and decreases changes in membrane permeability. However, inhibition of NCX1 enhances cell blebbing; cells become swollen because of NHE1 induced intracellular sodium accumulation. Our study found that NHE1 induced sodium influx is a driving force for membrane bleb growth, while sodium efflux (and calcium influx) induced by NCX1 in a reverse mode results in membrane bleb retraction. Together, these findings reveal a novel function for NHE1 and NCX1 in membrane blebbing and permeability, and establish a link between membrane blebbing and integrin signaling.

Yi, Yung-Hsiang; Chang, Yu-Sun; Lin, Chi-Hung; Lew, Tien-Shen; Tang, Chih-Yung; Tseng, Wei-Lien; Tseng, Ching-Ping; Lo, Szecheng J.

2012-01-01

94

Interaction of hydration and subfornical organ lesions in sodium-depletion induced salt appetite.  

PubMed

The authors tested whether the level of hydration after furosemide diuresis and 22 hr of sodium depletion affects the amount of water or 0.3 M NaCl solution consumed by rats with intact brains or with lesions of the subfornical organ (SFO). Rats received 2 (underhydrated) or 10 (euhydrated) ml/kg water by gavage as the only fluid input 2, 4, and 20 hr after 10 mg/kg furosemide. These hydration treatments had little or no effect on the amount of saline consumed in 2 hr by intact rats. SFO lesions reduced water intake regardless of hydration condition. Euhydrated, SFO-lesioned rats drank a normal amount of saline, but underhydrated, lesioned rats drank less saline than any other group. Thus, euhydration may facilitate salt appetite in SFO-lesioned rats, and the deficits in salt appetite noted in SFO-lesioned rats may result from deficits in water ingestion rather than from a destruction of angiotensin II receptor sites that directly provoke salt appetite. PMID:9109639

Starbuck, E M; Lane, J R; Fitts, D A

1997-02-01

95

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

Code of Federal Regulations, 2010 CFR

...calcium or sodium salts of a fatty acid mixture that is predominately stearic acid. Associated fatty acids, including palmitic acid and minor amounts of lauric, myristic, pentadecanoic, margaric, arachidic, and other fatty acids may be...

2010-04-01

96

Equilibrium hydrate formation conditions for hydrogen sulfide, carbon dioxide, and ethane in aqueous solutions of ethylene glycol and sodium chloride  

SciTech Connect

Natural gas components such as hydrogen sulfide, carbon dioxide, and ethane form gas hydrates of structure I under suitable temperature and pressure conditions. Information on such conditions is vital to the oil and gas industry in order to design and operate processing equipment and pipelines so that hydrate formation is avoided. Incipient equilibrium hydrate formation conditions for hydrogen sulfide, carbon dioxide, and ethane in aqueous solutions of ethylene glycol and sodium chloride were experimentally obtained in the temperature range 264--290 K and the pressure range 0.23--3.18 MPa. A variable-volume sapphire cell was used for the measurements.

Majumdar, A.; Mahmoodaghdam, E.; Bishnoi, P.R.

2000-02-01

97

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

NASA Astrophysics Data System (ADS)

A sodium brittle mica with the ideal composition [Na4]inter[Mg6]oct[Si4Al4]tetO20F4 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.

Kalo, Hussein; Milius, Wolfgang; Bru, Michael; Breu, Josef

2013-02-01

98

Calcium Transient and Sodium-Calcium Exchange Current in Human versus Rabbit Sinoatrial Node Pacemaker Cells  

PubMed Central

There is an ongoing debate on the mechanism underlying the pacemaker activity of sinoatrial node (SAN) cells, focusing on the relative importance of the membrane clock and the Ca2+ clock in the generation of the small net membrane current that depolarizes the cell towards the action potential threshold. Specifically, the debate centers around the question whether the membrane clock-driven hyperpolarization-activated current, I f, which is also known as the funny current or pacemaker current, or the Ca2+ clock-driven sodium-calcium exchange current, I NaCa, is the main contributor to diastolic depolarization. In our contribution to this journal's Special Issue on Cardiac Electrophysiology, we present a numerical reconstruction of I f and I NaCa in isolated rabbit and human SAN pacemaker cells based on experimental data on action potentials, I f, and intracellular calcium concentration ([Ca2+]i) that we have acquired from these cells. The human SAN pacemaker cells have a smaller I f, a weaker [Ca2+]i transient, and a smaller I NaCa than the rabbit cells. However, when compared to the diastolic net membrane current, I NaCa is of similar size in human and rabbit SAN pacemaker cells, whereas I f is smaller in human than in rabbit cells.

Verkerk, Arie O.

2013-01-01

99

Calcium transient and sodium-calcium exchange current in human versus rabbit sinoatrial node pacemaker cells.  

PubMed

There is an ongoing debate on the mechanism underlying the pacemaker activity of sinoatrial node (SAN) cells, focusing on the relative importance of the "membrane clock" and the "Ca(2+) clock" in the generation of the small net membrane current that depolarizes the cell towards the action potential threshold. Specifically, the debate centers around the question whether the membrane clock-driven hyperpolarization-activated current, I f , which is also known as the "funny current" or "pacemaker current," or the Ca(2+) clock-driven sodium-calcium exchange current, I NaCa, is the main contributor to diastolic depolarization. In our contribution to this journal's "Special Issue on Cardiac Electrophysiology," we present a numerical reconstruction of I f and I NaCa in isolated rabbit and human SAN pacemaker cells based on experimental data on action potentials, I f , and intracellular calcium concentration ([Ca(2+)] i ) that we have acquired from these cells. The human SAN pacemaker cells have a smaller I f , a weaker [Ca(2+)] i transient, and a smaller I NaCa than the rabbit cells. However, when compared to the diastolic net membrane current, I NaCa is of similar size in human and rabbit SAN pacemaker cells, whereas I f is smaller in human than in rabbit cells. PMID:23606816

Verkerk, Arie O; van Borren, Marcel M G J; Wilders, Ronald

2013-01-01

100

Development of a novel calcium phosphate cement composed mainly of calcium sodium phosphate with high osteoconductivity.  

PubMed

Two novel calcium phosphate cements (CPC) have been developed using calcium sodium phosphate (CSP) as the main ingredient. The first of these cements, labeled CAC, contained CSP, ?-tricalcium phosphate (TCP), and anhydrous citric acid, whereas the second, labeled CABC, contained CSP, ?-TCP, ?-TCP, and anhydrous citric acid. Biopex()-R (PENTAX, Tokyo, Japan), which is a commercially available CPC (Com-CPC), and OSferion() (Olympus Terumo Biomaterials Corp., Tokyo, Japan), which is a commercially available porous ?-TCP, were used as reference controls for analysis. In vitro analysis showed that CABC set in 5.7 0.3 min at 22 C and had a compressive strength of 86.0 9.7 MPa after 5 days. Furthermore, this material had a compressive strength of 26.7 3.7 MPa after 2 h in physiologic saline. CAC showed a statistically significantly lower compressive strength in the presence of physiologic saline and statistically significantly longer setting times than those of CABC. CABC and CAC exhibited apatite-forming abilities in simulated body fluid that were faster than that of Com-CPC. Samples of the materials were implanted into the femoral condyles of rabbits for in vivo analysis, and subsequent histological examinations revealed that CABC exhibited superior osteoconductivity and equivalent bioresorbability compared with Com-CPC, as well as superior osteoconductivity and bioresorbability compared with CAC. CABC could therefore be used as an alternative bone substitute material. PMID:24671331

Tanaka, Masashi; Takemoto, Mitsuru; Fujibayashi, Shunsuke; Kawai, Toshiyuki; Tsukanaka, Masako; Takami, Kimiaki; Motojima, Satoshi; Inoue, Hikaru; Nakamura, Takashi; Matsuda, Shuichi

2014-06-01

101

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

PubMed

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 89mg PO4-P/L. After 20min mixing, 1.5g/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, nosignificant carbonate inhibition was observed with P removal by A-CSHs. Moreover, Premoved by A-CSHs showed better settleability, filterability, and dewaterability than Pprecipitated 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

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

2013-05-01

102

Mechanisms of sodium/calcium selectivity in sodium channels probed by cysteine mutagenesis and sulfhydryl modification.  

PubMed Central

A conserved lysine residue in the "P loop" of domain III renders sodium channels highly selective. Conversion of this residue to glutamate, to mimic the homologous position in calcium channels, enables Ca2+ to permeate sodium channels. Because the lysine-to-glutamate mutation converts a positively charged side chain to a negative one, it has been proposed that a positive charge at this position suffices for Na+ selectivity. We tested this idea by converting the critical lysine to cysteine (K1237C) in mu 1 rat skeletal sodium channels expressed in Xenopus oocytes. Selectivity of the mutant channels was then characterized before and after chemical modification to alter side-chain charge. Wild-type channels are highly selective for Na+ over Ca2+ (PCa/PNa < 0.01). The K1237C mutation significantly increases permeability to Ca2+ (PCa/PNa = 0.6) and Sr2+. Analogous mutations in domains I (D400C), II (E755C), and IV (A1529C) did not alter the selectivity for Na+ over Ca2+, nor did any of the domain IV mutations (G1530C, W1531C, and D1532C) that are known to affect monovalent selectivity. Interestingly, the increase in permeability to Ca2+ in K1237C cannot be reversed by simply restoring the positive charge to the side chain by using the sulfhydryl modifying reagent methanethiosulfonate ethylammonium. Single-channel studies confirmed that modified K1237C channels, which exhibit a reduced unitary conductance, remain permeable to Ca2+, with a PCa/PNa of 0.6. We conclude that the chemical identity of the residue at position 1237 is crucial for channel selectivity. Simply rendering the 1237 side chain positive does not suffice to restore selectivity to the channel. Images FIGURE 2 FIGURE 7

Perez-Garcia, M T; Chiamvimonvat, N; Ranjan, R; Balser, J R; Tomaselli, G F; Marban, E

1997-01-01

103

The effect of dietary sodium on calcium metabolism in premenopausal and postmenopausal women  

Microsoft Academic Search

Objective: To investigate the effects of high and low sodium diets on urinary calcium, bone turnover and calcium absorption in pre and postmenopausal women. Design: Experimental, prospective and longitudinal study. Setting: Samples were taken at the hospital and the diets were followed at home. Subjects: Volunteers were recruited from the hospital and were either hospital staff or post-graduate students. No

CEL Evans; AY Chughtai; A Blumsohn; M Giles; R Eastell

1997-01-01

104

Evaluation of the Health Aspects of Ascorbic Acid, Sodium Ascorbate, Calcium Ascorbate, Erythorbic Acid, Sodium Erythorbate, and Ascorbyl Palmitate as Food Ingredients.  

National Technical Information Service (NTIS)

The report, by a group of qualified scientists designated the Select Committee of GRAS Substances (SCOGS), provides an independent evaluation of the safety of ascorbic acid, sodium ascorbate, calcium ascorbate, erythorbic acid, sodium erythorbate, and asc...

1979-01-01

105

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

PubMed

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

Vavrusova, Martina; Skibsted, Leif H

2014-01-01

106

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

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.

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

2004-05-01

107

Anticaries effect of dentifrices with calcium citrate and sodium trimetaphosphate  

PubMed Central

Because of the growing concerns regarding fluoride ingestion by young children and dental fluorosis, it is necessary to develop new dentifrices. Objective The aim of this study was to evaluate the effect of dentifrices with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel demineralization. Material and Methods Enamel blocks (n=70), previously selected through surface hardness analysis, were submitted to daily treatment with dentifrices diluted in artificial saliva and to a pH-cycling model. The fluoride concentration in dentifrices was 0, 250, 450, 550, 1,000 and 1,100 g F/g. CrestTM was used as a positive control (1,100 mg F/g). Cacit (0.25%) and TMP (0.25%) were added to dentifrices with 450 and 1,000 g F/g. Surface hardness was measured again and integrated loss of subsurface hardness and fluoride concentration in enamel were calculated. Parametric and correlation tests were used to determine difference (p<0.05) and dose-response relationship between treatments. Results The addition of Cacit and TMP did not provide a higher fluoride concentration in enamel, however it reduced (p<0.05) mineral loss when compared to other dentifrices; the dentifrice with Cacit and TMP and a low fluoride concentration presented similar results when compared to a dentifrice with 1,100 mg F/g (p>0.05). Conclusions Dentifrices with 450 and 1,000 g F/g, Cacit and TMP were as effective as a gold standard one.

DELBEM, Alberto Carlos Botazzo; BERGAMASCHI, Mauricio; RODRIGUES, Eliana; SASSAKI, Kikue Takebayashi; VIEIRA, Ana Elisa de Mello; MISSEL, Emilene Macario Coimbra

2012-01-01

108

Effect of curing temperature in some hydration characteristics of calcium aluminate cement compared with those of portland cement  

Microsoft Academic Search

In the present paper the hydration of 1:3 Calcium Aluminate Cement (CAC) and Portland Cement (PC) mortars at temperatures of 5 C, 20 C, and 60 C have been studied. An evaluation of the compressive and flexural strengths obtained from different curing conditions is made. The evolution of phases presented was also studied from XRD spectra. The relationship between the

P. Garcs; E. G Alcocel; S. Chinchn; C. G Andreu; J. Alcaide

1997-01-01

109

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

Microsoft Academic Search

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

F. Girardi; E. Sabbioni

1968-01-01

110

Renal handling of calcium and sodium in metastatic and non-metastatic malignancy.  

PubMed Central

Investigation of the renal handling of calcium and sodium in rehydrated patients with hypercalcaemia associated with malignancy showed enhanced reabsorption of calcium in most cases. This was a feature of both metastatic and non-metastatic malignancy, and in this respect the patients were indistinguishable from patients with primary hyperparathyroidism. As the increased calcium reabsorption was inversely correlated with the rate of excretion of sodium modest salt loading can be used to inhibit this process. This is an important practical aspect of the treatment of patients with this type of hypercalcaemia.

Heller, S R; Hosking, D J

1986-01-01

111

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

NASA Astrophysics Data System (ADS)

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.

Ming, Jinfa; Zuo, Baoqi

2014-01-01

112

Preparation,thermal, spectral and microscopic studies of calcium silicate hydratepoly(acrylicacid) nanocomposite materials  

Microsoft Academic Search

A series of calcium silicate hydrate (CSH)-polymer nanocomposite\\u000a (CSHPN) materials were prepared by incorporating poly(acrylic\\u000a acid) (PAA) into the inorganic layers of CSH during precipitation\\u000a of quasicrystalline CSH from aqueous solution. The as-synthesized\\u000a CSHPN materials were characterized by X-ray fluorescence (XRF),\\u000a X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy\\u000a (SEM-EDS), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric\\u000a analysis (TG) and differential scanning

S. C. Mojumdar; L. Raki

2006-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

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

2010-11-01

114

Surfactant-assisted sonochemical synthesis of hollow calcium silicate hydrate (CSH) microspheres for drug delivery.  

PubMed

Hollow calcium silicate hydrate (CSH) microspheres with diameters around 1 microm were synthesized by a surfactant-assisted sonochemical route, and the products were characterized by XRD, SEM, FETEM and BET techniques. The results suggested that the ultrasound radiation, surfactant and Ca source were important factors which affected the formation of hollow microspheres. Based on the observation of products in different reaction systems, the possible mechanism for the formation of hollow CSH spheres was discussed. Furthermore, gentamicin, a typical anti-inflammatory drug, was used to investigate the drug loading and release behavior of the hollow spheres. The results indicated that CSH hollow spheres had high drug loading capacity and favorable drug release behavior, and might be used for preparation of bone grafts with drug delivery properties. PMID:20207574

Zhang, Meili; Chang, Jiang

2010-06-01

115

{sup 17}O MAS NMR investigation of the structure of calcium silicate hydrate gel  

SciTech Connect

This paper presents the results of a systematic investigation of the structure of hydrothermally synthesized calcium silicate hydrate gel using {sup 17}O MAS NMR at 11.7 T and MAS frequencies up to 12 kHz. The results support the previously proposed defect-tobermorite structural model for C-S-H. At least six O-sites have been identified, two NBO, BO, Ca-OH, Si-OH, and H{sub 2}O. The compositional variation of the relative intensities of the signal for different sites measured by {sup 17}O NMR is consistent with that calculated from {sup 29}Si NMR results for the same samples. The chemical shifts of the NBO and BO sites become more deshielded (more positive) with increasing C/S ratio.

Cong, X.; Kirkpatrick, R.J. [Univ. of Illinois, Urbana, IL (United States)

1996-06-01

116

Hydration kinetics of CA{sub 2} and CA-Investigations performed on a synthetic calcium aluminate cement  

SciTech Connect

Much is already known about the hydration of monocalcium aluminate (CA) in calcium aluminate cements (CACs). CA{sub 2} is known to be weakly hydraulic. Therefore, the hydration kinetics of CA{sub 2} were not of as great interest as those of the hydration of CAC. We were able to show that the hydration of CA{sub 2} begins as soon as the hydration rate of CA has reached its maximum and the first precipitation of C{sub 2}AH{sub 8} has started. The hydration of different CA/CA{sub 2} ratios was analyzed by the G-factor quantification. The individual contributions of the phases CA and CA{sub 2} to the heat flow were calculated based on the amounts dissolved by applying thermodynamic data. The heat flow as calculated from XRD data was then compared with the measured heat flow. It obtained a good consistency between the two. The very pronounced influence of CA{sub 2} during hydration of CAC can be clearly demonstrated.

Klaus, S.R., E-mail: klaus@geol.uni-erlangen.de; Neubauer, J., E-mail: juergen.neubauer@gzn.uni-erlangen.de; Goetz-Neunhoeffer, F., E-mail: friedlinde.goetz@gzn.uni-erlangen.de

2013-01-15

117

Phosphoprotein staining for sodium dodecyl sulfate-polyacrylamide gel electrophoresis using fluorescent reagent morin hydrate.  

PubMed

A fluorescence-based stain with 3,5,7,2',4'-pentahydroxyflavone (morin hydrate, MH) was designed to stain phosphoproteins in one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Al(3+) was applied as a "fixed bridge," providing an efficient energy transfer channel between phosphoprotein and MH, to produce a strong fluorescent complex for the determination of phosphoprotein. As little as 62.5ng of ?-casein (7 or 8 phosphates) and ?-casein (5 phosphates), 125ng of ovalbumin (2 phosphates), and ?-casein (1 phosphate) could be visualized with a wide linear dynamic range. In comparison with conventional methods, MH stain is a time-saving method that takes just 90min. It also has good compatibility with routine protein stainings such as Coomassie Brilliant Blue R (CBBR) and SYPRO Ruby for total protein analysis. PMID:23274386

Wang, Xu; Hwang, Sun-Young; Cong, Wei-Tao; Jin, Li-Tai; Choi, Jung-Kap

2013-04-01

118

Are micelles needed to form methane hydrates in sodium dodecyl sulfate solutions?  

PubMed

The possibility that methane hydrates form in sodium dodecyl sulfate (SDS) water solutions without the help of micelles formation has been investigated. To asses whether micelles are needed for the hydrate to form only one SDS molecule has been considered. To figure out the possible mechanism through which the SDS promotes the formation of methane clathrate the dynamics of CH(4) solvation in the presence and absence of the surfactant molecule is monitored. To carry out the dynamical calculations, the SDS-H(2)O, SDS-CH(4), and CH(4)-H(2)O interactions were described using a recently proposed model potential. The adopted model leverages both on the decomposition of the molecular polarizability in effective components associated with the interaction centers distributed on the molecular frame and on the use of an improved Lennard-Jones functional form to represent the effective pair interaction energies. Molecular dynamics simulations performed on such potential, contrary to some earlier assumptions, do not support mechanisms requiring the formation of micelles as suggested by the findings of more recent experiments. PMID:22448641

Albert, M; Costantini, A; Lagan, A; Pirani, F

2012-04-12

119

Study on Immobilization Activated Sludge by Polyvinyl Alcohol-sodium Alginate - Calcium Nitrate in Domestic Sewage Treatment  

Microsoft Academic Search

Preparation conditions of immobilization activated sludge were studied with polyvinyl alcohol-sodium alginate as carrier and calcium nitrate as cross linking agent. Physical properties and removal effect of immobilization activated sludge were also investigated, where cross linking agent was boric acid, calcium chloride, calcium nitrate, respectively. The effect of sewage treatment was compared with activated sludge cross optimum linker calcium nitrate

Nie Qian; Jian Peichao; Liu Zhibin; Gu Fang

2010-01-01

120

Interaction of Nanostructured Calcium Silicate Hydrate with Ibuprofen Drug Molecules: X-ray Absorption Near Edge Structure (XANES) Study at the Ca, Si and O K-edge  

NASA Astrophysics Data System (ADS)

Mesoporous calcium silicate hydrate (CSH) nanostructure has been proven to be bioactive and biocompatible, and has a bright future in the application of bone treatment among other applications. X-ray absorption near edge structure (XANES) is a powerful tool for the study of the interactions of calcium silicate hydrates with drug molecules because it is element specific and it probes the unoccupied electronic states. Herein, we report the use of the calcium, silicon and oxygen K-edge XANES spectroscopy to identify how drug molecules interact with different groups in calcium silicate hydrate mesoporous nano-carriers with different morphologies. Significant changes are observed in XANES spectra after drug loading into the calcium silicate hydrate system, especially at the Si and O K-edge. The implications of these findings are discussed.

Guo, X. X.; Sham, T. K.; Zhu, Y. J.; Hu, Y. F.

2013-04-01

121

Molecular dynamics study on the growth of structure I methane hydrate in aqueous solution of sodium chloride.  

PubMed

The structure, thermodynamic, and kinetic properties of methane hydrates formed from the aqueous solution of sodium chloride are investigated based on molecular dynamics simulations. A three-phase molecular model consisting of a slab of methane hydrate phase, a slab of liquid water containing sodium chloride, and a gas phase of methane molecules is used. The decrease in the three-phase coexisting temperatures (by 2-3 K) at different pressures (10-100 MPa) for aqueous NaCl solutions (about 2 mol %) confirms the thermodynamic inhibition of NaCl. The growth rate of methane hydrates in NaCl solution is found to be half to one-third of that in pure water. The kinetic inhibition of NaCl is found to be a result of the reduced water repelling at the growing interface due to the strong hydration of ions. Individual ions or NaCl ion pairs can replace water molecules to participate in the formation of the cage structures. The distortion of water cages due to the presence of ions may result in a reduced fraction of occupation of methane in the cage cavities. Our results provide useful insights into the mechanism of growth of methane hydrates in seawater and the desalination. PMID:23137227

Tung, Yen-Tien; Chen, Li-Jen; Chen, Yan-Ping; Lin, Shiang-Tai

2012-12-01

122

Unique extraction behavior of americium and curium in a system of TBP and calcium nitrate hydrate melt  

NASA Astrophysics Data System (ADS)

Extraction of Am(III) and Cm(III) between tri-n-butyl phosphate solution and molten calcium nitrate hydrate Ca(NO3)2RH2O was investigated radiochemically. In the range of water content R = 3.5-8.0, the distribution ratio was found to increase with the decrease of water activity. The dependence of the distribution ratios on the water activity in the hydrate melt changes at around log aH2O = -0.4, which corresponds to R = 5.0. The extraction behavior of Am(III) and Cm(III) was systematically discussed with the reported data of trivalent lanthanides.

Okude, G.; Fujii, T.; Uehara, A.; Sekimoto, S.; Minato, K.; Yamana, H.

2010-03-01

123

Crystal structure of usnic acid sodium salt 2 1\\/2 hydrate  

Microsoft Academic Search

Usnic acid, 1,3(2H,9bH)-dibenzofurandione-2,6-diacetyl-7,9-dihydroxy-8,9b-dimethyl, (1) was isolated from the lichenUsnea barbata by supercritical CO2 extraction. The corresponding sodium salt 2 1\\/2 hydrate was obtained by reacting the acid with sodium carbonate. (C18H15O7Na2.5 H2O) 2,Mr=822.68, triclinic,P1,a=14.179(8),b=7.369(4),c=9.109(6),a=88.47(2),=105.35(2),?=92.27(2),V=917(2)3,Z=1,Dx=1.490 g cm-3, ?(MoKa)=0.71073 ,=1.32 cm-1,F(000)=430,T=293(2)K. The structure was solved by direct methods and refined toR=0.038 for 3229 observed reflections. Both Na ions are pentacoordinated. Their

B. Ribr; A. Kapor; Gy. Argay; P. Engel; Z. Djarmati; R. M. Jankov

1993-01-01

124

Adsorption of sodium polyacrylate in high solids loading calcium carbonate slurries  

Microsoft Academic Search

The adsorption of sodium polyacrylate (NaPAA) in slurries with up to 75wt.% calcium carbonate was investigated with the use of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and adsorption of probe molecules. Analysis of the IR spectra demonstrated that the carboxylate groups of NaPAA adsorbed onto ground calcium carbonate (GCC) in three different modes. These modes were shown to be

Joshua J. Taylor; Wolfgang M. Sigmund

2010-01-01

125

Inhibitive effect of calcium gluconate and sodium molybdate on carbon steel  

Microsoft Academic Search

There is an increasing demand for eco-friendly inhibitors for use in cooling water systems. Both calcium gluconates and molybdate are eco-friendly, non-toxic chemicals. The corrosion inhibition of calcium gluconate and sodium molybdate on carbon steel in neutral aqueous media was evaluated by means of weight loss, electrochemical polarisation and impedance techniques. A synergistic effect was observed when these two eco-friendly

S. M. A. Shibli; V. Anitha Kumary

2004-01-01

126

Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines  

SciTech Connect

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.

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

2007-08-11

127

Calcium gluconate and sodium succinate for therapy of sodium fluoroacetate experimental intoxication in cats: clinical and electrocardiographic evaluation.  

PubMed

Sodium fluoroacetate (SFAC) or Compound 1080 is a potent rodenticide, largely used after 1946 for rodent and home pest control. The toxic effects of SFAC are caused by fluorocitrate action, a toxic metabolite, which has a competitive action with aconitase enzyme, leading to citrate accumulation and resulting in interference in energy production by Krebs cycle blockade. In the present study, domestic cats were intoxicated with oral doses of fluoroacetate (0.45 mg/kg). The intoxicated animals presented emesis, diarrhea with abdominal pain posture and an abdominal palpation, tachypnea, bilateral midriasis, hypothermia, hyperexcitability and convulsions. Blood gas analysis indicated decreased pH and bicarbonate levels. Serum ionized calcium was also decreased. ECG showed non-specific changes in ventricular repolarization and ventricular arrhythmias. The survival rate was 75% in the treated group with calcium gluconate and sodium succinate and 37.5% in the nontreated group. PMID:16696292

Collicchio-Zuanaze, R C; Sakate, M; Schwartz, D S; Trezza, E; Crocci, A J

2006-04-01

128

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

SciTech Connect

{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.

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

129

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

SciTech Connect

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.

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

1983-05-01

130

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

NASA Technical Reports Server (NTRS)

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..

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

2000-01-01

131

27Al and 29Si solid-state NMR characterization of calcium-aluminosilicate-hydrate.  

PubMed

Calcium silicate hydrate (C-S-H) is the main constituent of hydrated cement paste and determines its cohesive properties. Because of the environmental impact of cement industry, it is more and more common to replace a part of the clinker in cement by secondary cementitious materials (SCMs). These SCMs are generally alumina-rich and as a consequence some aluminum is incorporated into the C-S-H. This may have consequences on the cohesion and durability of the material, and it is thus of importance to know the amount and the location of Al in C-S-H and what the parameters are that control these features. The present paper reports the (29)Si and (27)Al MAS NMR analyses of well-characterized C-A-S-H samples (C-S-H containing Al). These samples were synthesized using an original procedure that successfully leads to pure C-A-S-H of controlled compositions in equilibrium with well-characterized solutions. The (27)Al MAS NMR spectra were quantitatively interpreted assuming a tobermorite-like structure for C-A-S-H to determine the aluminum location in this structure. For this purpose, an in-house written software was used which allows decomposing several spectra simultaneously using the same constrained spectral parameters for each resonance but with variable intensities. The hypothesis on the aluminum location in the C-A-S-H structure determines the proportion of each silicon site. Therefore, from the (27)Al NMR quantitative results and the chemical composition of each sample, the intensity of each resonance line in the (29)Si spectra was set. The agreement between the experimental and calculated (29)Si MAS NMR spectra corroborates the assumed C-A-S-H structure and the proposed Al incorporation mechanism. The consistency between the results obtained for all compositions provides another means to assess the assumptions on the C-A-S-H structure. It is found that Al substitutes Si mainly in bridging positions and moderately in pairing positions in some conditions. Al in pairing site is observed only for Ca/(Si+Al) ratios greater than 0.95 (equivalent to 4 mmol.L(-1) of calcium hydroxide). Finally, the results suggest that penta and hexa-coordinated aluminum are adsorbed on the sides of the C-A-S-H particles. PMID:22277014

Pardal, Xiaolin; Brunet, Francine; Charpentier, Thibault; Pochard, Isabelle; Nonat, Andr

2012-02-01

132

Studies on the influence of spent FCC catalyst on hydration of calcium aluminate cements at ambient temperature  

Microsoft Academic Search

The influence of spent catalyst from catalytic cracking in fluidized bed (FCC) on the hydration of two kinds of calcium aluminate\\u000a cements (of about 40 and 70% content of alumina) was studied. Cement pastes were prepared with constant ratio of water\\/binder=0.5\\u000a and with content of 0, 5 and 25% mass of addition as replacement of cement. The samples were stored

B. Pacewska; M. Nowacka; I. Wili?ska; W. Kubissa; V. Antonovich

2011-01-01

133

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

NASA Astrophysics Data System (ADS)

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, strtlingite 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.

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

2010-06-01

134

Calcium silicate hydrates investigated by solid-state high resolution {sup 1}H and {sup 29}Si nuclear magnetic resonance  

SciTech Connect

This work focuses on phases formed during cement hydration under high pressure and temperature: portlandite Ca(OH){sub 2} (CH); hillebrandite Ca{sub 2}(SiO{sub 3})(OH){sub 2} ({beta}-dicalcium silicate hydrate); calcium silicate hydrate (C-S-H); jaffeite Ca{sub 6}(Si{sub 2}O{sub 7})(OH){sub 6} (tricalcium silicate hydrate); {alpha}-C{sub 2}SH Ca{sub 2}(SiO{sub 3})(OH){sub 2} ({alpha}-dicalcium silicate hydrate); xonotlite Ca{sub 6}(Si{sub 6}O{sub 17})(OH){sub 2} and kilchoanite Ca{sub 6}(SiO{sub 4})(Si{sub 3}O{sub 10}). Portlandite and hillebrandite were synthesized and characterised by high resolution solid-state {sup 1}H and {sup 29}Si Nuclear Magnetic Resonance. In addition, information from the literature concerning the last five phases was gathered. In certain cases, a schematic 3D-structure could be determined. These data allow identification of the other phases present in a mixture. Their morphology was also observed by Scanning Electron Microscopy.

Meducin, Fabienne [Laboratoire de Physique et Mecanique des Milieux Heterogenes, Ecole Superieure de Physique et Chimie Industrielles, 75231 Paris Cedex 05 (France)]. E-mail: meducin@cnrs-orleans.fr; Bresson, Bruno [Laboratoire de Physique Quantique, ESPCI (France); Lequeux, Nicolas [Laboratoire de Physico-Chimie des polymeres et des milieux disperses, ESPCI (France); Noirfontaine, Marie-Noelle de [Laboratoire CECM-CNRS, 15, rue Georges Urbain, 94407 Vitry sur Seine (France); Zanni, Helene [Laboratoire de Physique et Mecanique des Milieux Heterogenes, Ecole Superieure de Physique et Chimie Industrielles, 75231 Paris Cedex 05 (France)

2007-05-15

135

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

PubMed

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, strtlingite, 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

Berger, Stphane; Cau Dit Coumes, Cline; Le Bescop, Patrick; Damidot, Denis

2011-10-30

136

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

SciTech Connect

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.

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

2004-02-01

137

Neonatal Parenteral Nutrition Containing Calcium Chloride and Sodium Phosphate: Mineral Intake and Aluminum Content  

Microsoft Academic Search

Objective. The authors objectives were to determine mineral as well as Al intakes for ?1000 g birth weight (ELBW) infants supported with parenteral nutrition (PN) solutions containing calcium chloride (CaCl) and sodium phosphate (NaPhos). Study design. This study was a prospective cohort study of 32 ELBW infants. Nutrient and Al intakes were recorded based on actual fluid intakes and concentrations

Robert K. Huston; Elizabeth A. McCulley; Andrea M. Markell; Carl F. Heisel; Patrick K. Lewallen

2012-01-01

138

Determination of Calcium, Magnesium, and Sodium in Wastewater by Inductively Coupled Plasma Spectroscopy.  

National Technical Information Service (NTIS)

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) has been used for the determination of calcium, magnesium, and sodium in industrial wastewater samples. The method developed employs the Qualitative mode of a Leeman Labs Plasma-Spec III In...

B. S. Barnes A. F. Volesky

1988-01-01

139

Sodium Sulfate Corrosion of Silicon Carbide Fiber-Reinforced Calcium Aluminosilicate Glass-Ceramic Matrix Composites.  

National Technical Information Service (NTIS)

Hot corrosion effects of Sodium Sulfate (NaSO4) coated Calcium Aluminosilicate (CAS)/Silicon Carbide (SiC) reinforced glass-ceramic matrix composite were investigated using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and X-r...

P. J. Newton

1994-01-01

140

Selective Measurement of Calcium and Sodium Ion Conductance Using Sub-Micropipette Probes with Ion Filters  

NASA Astrophysics Data System (ADS)

Selective ion currents in aqueous calcium chloride and sodium chloride solutions with concentrations of up to 1.0 M were observed with sub-micropipettes in which poly(vinyl chloride) (PVC) films containing ionophores selectively filtered cations. Calcium bis[4-(1,1,3,3-tetramethyl butyl)phenyl] phosphate (HDOPP-Ca) and bis[(12-crown-4)methyl]-2-dodecyl-2-methylmalonate [bis(12-crown-4)] were used as the ionophores to filter calcium and sodium ions, respectively. The selective ion current was observed using a low-current detection system developed from scanning tunneling microscopy. The approximate linear relationship between the ion concentration and ion current suggests that the sub-micropipette probe can be used to detect the intracellular local concentration of a specific ion up to 1.0 M.

Deng, Xiao Long; Takami, Tomohide; Son, Jong Wan; Kawai, Tomoji; Park, Bae Ho

2012-02-01

141

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

Microsoft Academic Search

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.

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

1984-01-01

142

Prediction of incompatibility of ceftriaxone sodium with calcium ions using the ionic product.  

PubMed

The purpose of this study was to evaluate the incompatibility of ceftriaxone sodium with calcium-containing products using the ionic product of precipitation, and the measurement of insoluble microparticles using a light obscuration particle counter. Appropriate volumes of 2% (w/v) calcium chloride solution were added to 0.4-2 mg/ml ceftriaxone isotonic sodium chloride solution, to make solutions with a final calcium ion concentration of 1.25 mmol/l. The solutions were gently agitated and stored at 37 degrees C for 24 h. The number of insoluble microparticles with a diameter less than 10 microm in the mixed sample solution, determined using a light obscuration particle counter, was increased when the ceftriaxone concentration was > or =0.8 mg/ml. The Saturation Index (defined as the ratio of the ionic product to the solubility product constant) of the prepared mixed solution was 1.1. A white precipitate could be observed visually when the ceftriaxone concentration of the sample solution was 7 mg/ml; the Saturation Index of the solution was 9.7. The effect of the calcium source on incompatibility with ceftriaxone sodium was also evaluated. The numbers of insoluble microparticles in sample solutions made by adding calcium chloride to the sample were significantly higher than those made by adding calcium gluconate. These results suggest that ceftriaxone should not be co-administered with calcium-containing products even if no precipitation is observed visually. There will still be insoluble microparticles caused by incompatibility in the sample solution when the Saturation Index of the solution is over 1.0. PMID:20046072

Nakai, Yuka; Tokuyama, Emi; Yoshida, Miyako; Uchida, Takahiro

2010-01-01

143

Collapse of sodium polyacrylate chains in calcium salt solutions  

Microsoft Academic Search

: The sodium salt of polyacrylic acid (NaPA) precipitates in the presence of Ca2+-ions. This phase behaviour can be represented by a phase diagram where the critical NaPA concentration is plotted versus the critical Ca2+ concentration resulting in a straight line as a phase boundary. The location of this phase boundary is influenced by the\\u000a presence of an inert monovalent

R. Schweins; K. Huber

2001-01-01

144

The effects of sodium lauryl sulphate and its oxidative breakdown products on calcium phosphate precipitation and transformation.  

PubMed

Most commercial dentifrices contain sodium lauryl sulphate, which oxidizes upon storage. The effects of aged sodium lauryl sulphate and its oxidative breakdown products on the conversion of amorphous calcium phosphate to hydroxyapatite were studied in vitro by a pH drop method. Hydroxyapatite was identified from its X-ray diffraction pattern. With storage time, the concentration of dodecanol [CH3(CH2)11OH], a breakdown product of sodium lauryl sulphate, increased. The storage dodecanol-containing sodium lauryl sulphate accelerated the conversion of amorphous calcium phosphate to hydroxyapatite. Dodecanol mixed with sodium lauryl sulphate accelerated the conversion when added both before and after initial formation of amorphous calcium phosphate. A stored commercial dentifrice also accelerated the conversion of amorphous calcium phosphate to hydroxyapatite. It was found that the concentration of dodecanol increased 2-fold over a 2-month period. PMID:1375020

Hidaka, S; Abe, K

1992-03-01

145

Toward a microscopic understanding of the calcium-silicate-hydrates/water interface  

NASA Astrophysics Data System (ADS)

Calcium-Silicate-Hydrates (C-S-H) are the main binding phases in most concrete which is the primarily used composite construction material in the world. However, a big lack is cleaving between the actual knowledge about C-S-H, compared to what could be reached using state-of-the-art technologies of modern research. In this article, the formation of a C-S-H phase on a native oxide covered silicon wafer is investigated by means of in-situ attenuated total reflection infrared (ATR-IR) and ex-situ surface-enhanced Raman spectroscopy (SERS). The total thickness of the C-S-H phase is determined by X-ray photoelectron spectroscopy (XPS) to be 3 nm. The formation appears to be reversible depending on the environment pH value and can be performed at room temperature. Based on density functional theory (DFT) calculations, it is shown that the C-S-H phase in the presence of water will change its chemical composition in order to reach the thermodynamic ground state of the system. This change is achieved by a metal-proton exchange reaction. The stoichiometry of these metal-proton exchange reactions is nearly independent of the environment pH value. Electrokinetic measurements yield isoelectric points of 2.0 and 2.6 for the native oxide covered silicon wafer (SiO2) and the C-S-H phase. This is consistent with a predominance of Si-O sites at the C-S-H/water interface.

Ebbert, Christoph; Grundmeier, Guido; Buitkamp, Nadine; Krger, Alexander; Messerschmidt, Florian; Thissen, Peter

2014-01-01

146

Amorphous calcium silicate hydrate/block copolymer hybrid nanoparticles: synthesis and application as drug carriers.  

PubMed

Amorphous calcium silicate hydrate (CSH)/block copolymer monomethoxy(polyethyleneglycol)-block-poly(lactide-co-glycolide) (mPEG-PLGA) (CSHP) hybrid nanoparticles have been prepared in aqueous solution via a facile coprecipitation route at room temperature. The block copolymer mPEG-PLGA micelles in aqueous solution serve as the templates, and the CSH links to the micelles by hydrogen bonding between the silanol groups and the hydrophilic mPEG segments. The obtained core/shell hybrid nanoparticles can be transformed to solid hybrid nanoparticles by washing with water. The drug ibuprofen (IBU) loading capacity of the CSHP hybrid nanoparticles is ultrahigh (~1.9 g drug per g carrier), and the IBU loading efficiency can reach as high as ~100%. The drug release of loaded IBU in the CSHP hybrid nanoparticles has been investigated in simulated body fluid (SBF). The loaded IBU drug in CSHP hybrid nanoparticles can release in SBF for a long period of time (about 300 h), during which the CSHP nanocarrier is completely transformed to hydroxyapatite, exhibiting a good bioactivity. The IBU drug release profile can be interpreted by the Higuchi model. The loading capacity for the anticancer drug docetaxel (DTX) in the CSHP hybrid nanoparticles is about 82 mg g(-1). More importantly, the release of the loaded DTX in phosphate buffer saline (PBS) at pH 5.5 is obviously faster than that at pH 7.4, which is promising for the application in cancer therapy. Human gastric carcinoma (SGC-7901) cells can be effectively killed in the presence of the DTX-loaded CSHP hybrid nanoparticles at appropriate concentrations. Thus, the CSHP hybrid nanoparticles are promising nanocarriers in drug delivery. Furthermore, the hemoglobin (Hb) loading capacity of CSHP hybrid nanoparticles can achieve an utrahigh value of 995 mg g(-1), suggesting that the as-prepared CSHP hybrid nanoparticles are excellent protein adsorbents. PMID:23511873

Wu, Jin; Zhu, Ying-Jie; Chen, Feng; Zhao, Xin-Yu; Zhao, Jing; Qi, Chao

2013-05-21

147

Adsorption of sodium polyacrylate in high solids loading calcium carbonate slurries.  

PubMed

The adsorption of sodium polyacrylate (NaPAA) in slurries with up to 75 wt.% calcium carbonate was investigated with the use of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and adsorption of probe molecules. Analysis of the IR spectra demonstrated that the carboxylate groups of NaPAA adsorbed onto ground calcium carbonate (GCC) in three different modes. These modes were shown to be dependent on the solids loading and age of the slurry. Further investigation lead to the determination of the chelating ability of NaPAA at high solids loading. PMID:19875128

Taylor, Joshua J; Sigmund, Wolfgang M

2010-01-15

148

Hydration and strength development of binder based on high-calcium oil shale fly ash  

Microsoft Academic Search

The properties of high-calcium oil shale fly ash and low-calcium coal fly ash, which are produced in Israeli power stations, were investigated. High-calcium oil shale fly ash was found to contain a great amount of CaOfree and SO3 in the form of lime and anhydrite. Mixtures of high-calcium oil shale fly ash and low-calcium coal fly ash, termed fly ash

C Freidin

1998-01-01

149

EFFECTS OF SODIUM AND CALCIUM IN LIGNITE ON THE PERFORMANCE OF ACTIVATED CARBON PRODUCTS  

SciTech Connect

Powdered activated carbon (PAC) has traditionally been used by the water treatment industry for the removal of compounds contributing to taste and odor problems. PAC also has the potential to remove naturally occurring organic matter (NOM) from raw waters prior to disinfection, thus controlling the formation of regulated disinfection by-products (DBPs). Many small water systems are currently using PAC for taste and odor control and have the potential to use PAC for controlling DBPs. The Energy & Environmental Research Center has been working on the development of a PAC product to remove NOM from surface water supplies to prevent the formation of carcinogenic DBPs during chlorination. During previous studies, the sodium and calcium content of the lignites showed a significant effect on the sorption capacity of the activated carbon product. As much as a 130% increase in the humic acid sorption capacity of a PAC produced from a high-sodium-content lignite was observed. During this study, activated carbons were prepared from three coals representing high-sodium, low-sodium--low-calcium, and high-calcium compositions in two steps, an initial char formation followed by mild activation with steam to avoid excessive burnout. This set of carbons was characterized with respect to physical and chemical properties. The BET (Brunauer-Emmett-Teller) nitrogen adsorption isotherms gave relatively low surface areas (ranging from 245 to 370 m{sup 2}/g). The lowest-BET area was obtained for the high-sodium carbon, which can be attributed to enlargement of micropores as a result of sodium-catalyzed gasification reaction of the carbon structure. This hypothesis is consistent with the scanning electron microscopy microprobe analyses, which show that in both the coal and the activated carbon from this coal, the sodium is distributed over both the carbon structure and the mineral particles. Thus it is initially associated with carboxylate groups on the coal and then as sodium oxide or other active form in close proximity to the carbon and is, therefore, readily available for catalysis of gasification. Humate adsorption isotherms for the high-sodium carbon gave superior results as defined by very high intercepts in modified Freundlich plots. Thus the high-sodium carbon will be considerably more effective in reducing the humate concentration for a given carbon dosage. Analysis of adsorption isotherms indicated the results were consistent with the hypothesis that only the larger pores are effective for binding the large humate molecules, and that the larger pores developed during activation of the high-sodium char give the appropriate macropore structure for humate binding. Toluene adsorption isotherms indicated that the high-calcium carbon and the low-calcium, low-sodium carbon were superior to the high-sodium carbon for small molecules in aqueous solution, but not as effective as a Calgon F-400 commercial activated carbon. This is consistent with the low-BET surface areas observed for the lignite-derived carbons, and thus there are a lower number of sites for binding the smaller toluene molecule in these carbons.

Edwin S. Olson; Kurt E. Eylands; Daniel J. Stepan

2001-12-01

150

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

NASA Astrophysics Data System (ADS)

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.

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

2011-08-01

151

Sodium-calcium exchanger and multiple sodium channel isoforms in intra-epidermal nerve terminals  

PubMed Central

Background Nociception requires transduction and impulse electrogenesis in nerve fibers which innervate the body surface, including the skin. However, the molecular substrates for transduction and action potential initiation in nociceptors are incompletely understood. In this study, we examined the expression and distribution of Na+/Ca2+ exchanger (NCX) and voltage-gated sodium channel isoforms in intra-epidermal free nerve terminals. Results Small diameter DRG neurons exhibited robust NCX2, but not NCX1 or NCX3 immunolabeling, and virtually all PGP 9.5-positive intra-epidermal free nerve terminals displayed NCX2 immunoreactivity. Sodium channel NaV1.1 was not detectable in free nerve endings. In contrast, the majority of nerve terminals displayed detectable levels of expression of NaV1.6, NaV1.7, NaV1.8 and NaV1.9. Sodium channel immunoreactivity in the free nerve endings extended from the dermal boundary to the terminal tip. A similar pattern of NCX and sodium channel immunolabeling was observed in DRG neurons in vitro. Conclusions NCX2, as well as NaV1.6, NaV1.7, NaV1.8 and NaV1.9, are present in most intra-epidermal free nerve endings. The presence of NCX2, together with multiple sodium channel isoforms, in free nerve endings may have important functional implications.

2010-01-01

152

Pore solution in alkali-activated slag cement pastes. Relation to the composition and structure of calcium silicate hydrate  

SciTech Connect

In this work, the relationship between the composition of pore solution in alkali-activated slag cement (AAS) pastes activated with different alkaline activator, and the composition and structure of the main reaction products, has been studied. Pore solution was extracted from hardened AAS pastes. The analysis of the liquids was performed through different techniques: Na, Mg and Al by atomic absorption (AA), Ca ions by ionic chromatography (IC) and Si by colorimetry; pH was also determined. The solid phases were analysed by XRD, FTIR, solid-state {sup 29}Si and {sup 27}Al NMR and BSE/EDX. The most significant changes in the ionic composition of the pore solution of the AAS pastes activated with waterglass take place between 3 and 24 h of reaction. These changes are due to the decrease of the Na content and mainly to the Si content. Results of {sup 29}Si MAS NMR and FTIR confirm that the activation process takes place with more intensity after 3 h (although at this age, Q{sup 2} units already exist). The pore solution of the AAS pastes activated with NaOH shows a different evolution to this of pastes activated with waterglass. The decrease of Na and Si contents progresses with time. The nature of the alkaline activator influences the structure and composition of the calcium silicate hydrate formed as a consequence of the alkaline activation of the slag. The characteristic of calcium silicate hydrate in AAS pastes activated with waterglass is characterised by a low structural order with a low Ca/Si ratio. Besides, in this paste, Q{sup 3} units are detected. The calcium silicate hydrate formed in the pastes activated with NaOH has a higher structural order (higher crystallinity) and contains more Al in its structure and a higher Ca/Si ratio than those obtained with waterglass.

Puertas, F.; Fernandez-Jimenez, A.; Blanco-Varela, M.T

2004-01-01

153

Detoxification of Cyanide in a Gold Processing Plant Tailings Water Using Calcium and Sodium Hypochlorite  

Microsoft Academic Search

In laboratory experiments, cyanide in waste water from the Muteh gold mine in Iran was oxidized by sodium and calcium hypochlorite\\u000a to cyanate (CNO?), which is 1,000 times less environmentally hazardous than cyanide. Experiments were conducted using waste water containing\\u000a 270mg\\/L cyanide over a pH range of 613 and temperatures between 25 and 50C. Cyanide was removed completely at a

A. Khodadad; P. Teimoury; M. Abdolahi; A. Samiee

2008-01-01

154

The effects of sodium hypochlorite and calcium hydroxide on tissue dissolution and root canal cleanliness  

Microsoft Academic Search

Summary In this in vitro study, we investigated the efficacy of sodium hypochlorite (NaOCl) and calcium hydroxide (Ca(OH) 2 ) in dissolving necrotic tissue and cleaning root canals. In the first part of the study, 0.5% NaOCl solution and Ca(OH) 2 paste and solution were tested with samples of necrotic bovine muscle in different treat- ment modes and for different

M. Turkun; T. Cengiz

1997-01-01

155

The determination of calcium, magnesium, and sodium in wastewater by inductively coupled plasma spectroscopy  

SciTech Connect

Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) has been used for the determination of calcium, magnesium, and sodium in industrial wastewater samples. The method developed employs the Qualitative mode of a Leeman Labs Plasma-Spec III Inductively Coupled Plasma (ICP) Spectrometer. Analytical results using the Qualitative mode were compared to those obtained using ICP Sequential analysis, flame atomic absorption spectrophotometry (AAS), and flame emission. 1 ref., 6 tabs.

Barnes, B.S.; Volesky, A.F.

1988-10-01

156

Kinetics of HCl reactions with calcium and sodium sorbents for IGCC fuel gas cleaning  

Microsoft Academic Search

Experiments for HCl sorption by calcium and sodium sorbents have been carried out with simulated gases of compositions typical for air-blown and oxygen-blown IGCC fuel gases. The concentration of CO2 affects the behaviour of HCl sorption by Ca-sorbents but does not influence the performance of Na-sorbents in the temperature range 300600C. The sorbent particle size has a slight effect on

J. H. A. Kiel; A. Bos; H. Den Uil

1996-01-01

157

Collapse of sodium polyacrylate chains in calcium salt solutions  

NASA Astrophysics Data System (ADS)

The sodium salt of polyacrylic acid (NaPA) precipitates in the presence of Ca^{2+}-ions. This phase behaviour can be represented by a phase diagram where the critical NaPA concentration is plotted versus the critical Ca^{2+} concentration resulting in a straight line as a phase boundary. The location of this phase boundary is influenced by the presence of an inert monovalent salt like NaCl. The present contribution focuses on the coil dimensions of NaPA chains in dilute aqueous solution corresponding to the one phase region of such a phase diagram. A variety of parameters with which the size and shape of the polyelectrolyte chains can be modulated are revealed. Approaching the phase boundary by decreasing the NaPA concentration at a constant Ca^{2+} content leads to a collapse of the NaPA chains. Combined static and dynamic light scattering suggests a compact spherical shape as the final state of this transition, both in 0.1 M NaCl and in 0.01 M NaCl. In the lower NaCl concentration, indication is presented for the existence of a cigar or pearl necklace like intermediate. Most strikingly, the collapsed chains can be reexpanded by increasing the concentration of inert NaCl at constant content of NaPA and Ca^{2+}. Clearly, excessive Na+-ions displace the Ca^{2+}-ions from the NaPA chains.

Schweins, R.; Huber, K.

158

Formation of Calcium Aluminate Hydrates in Reactions between Calcium Hydroxide Slurries and Al-Containing Minerals and Rocks.  

National Technical Information Service (NTIS)

The reactions between Ca(OH)2 and Al-containing minerals and rocks were examined. Tetracalcium aluminate hydrates and hydrogarnets were identified in the reaction products. The significance of this in relation to portland cement mortar and concrete was co...

J. H. P. van Aardt S. Visser

1983-01-01

159

The characterization of hardened alkali-activated blast-furnace slag pastes and the nature of the calcium silicate hydrate (CSH) phase  

Microsoft Academic Search

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

I. G. Richardson; A. R. Brough; G. W. Groves; C. M. Dobson

1994-01-01

160

Digoxin-like immunoreactive factor in rat plasma: effect of sodium and calcium intake.  

PubMed

Studies have been performed in rats to determine whether an endogenous material capable of binding to digoxin antibodies is present in the plasma. Such a material has been shown in other species and has been hypothesized to represent an endogenous ligand for the receptor on Na-K ATPase through which cardiac glycosides act. In rats consuming a normal rodent chow (1% calcium by weight) and drinking deionized water, endogenous binding of digoxin antibody in radioimmunoassay amounted to 23.1 +/- 4.6 fM digoxin equivalents/100 microliter of plasma (mean +/- SEM, n = 8). Since a hypothetical role for such an endogenous ligand is the regulation or renal sodium excretion by inhibition of renal Na-K ATPase, the effect of increased sodium intake on plasma levels of this digoxin-like immunoreactive factor (DLIF) was studied. Animals consuming the same chow, but drinking 0.5% NaCl solution in place of water for a 4 week period showed significantly greater DLIF in plasma which was measured at 109.2 +/- 20.3 fM digoxin equivalents/100 microliter of plasma (p less than 0.001). Because DLIF has been implicated in the pathogenesis of hypertension we also studied the effects of calcium intake on plasma levels of DLIF. In previous studies we have shown that rats allowed to drink 0.5% saline develop a moderate hypertension which can be reversed with calcium supplementation. In the present studies, 3 dietary calcium subgroups (0.01% Ca, 1.0% Ca and 4% Ca) were formed among animals drinking water or 0.5% saline for 4 weeks. No effect of low calcium intake on plasma DLIF was found either in water or saline drinkers. However, calcium supplementation produced a significant reduction in plasma DLIF in both water and saline drinking animals. PMID:2828804

Doris, P A

1988-01-01

161

Aspects on the Interaction between Sodium Carboxymethylcellulose and Calcium Carbonate and the Relationship to Specific Site Adsorption  

Microsoft Academic Search

The mechanisms of adsorption and association for sodium carboxymethylcellulose (NaCMC) in calcium carbonate suspensions have been determined from isothermal calorimetry and adsorption measurements. The equilibrium adsorption isotherms were determined by two different methods of separation; a depletion method and a serum exchange method. The enthalpy of dilution for NaCMC was determined on supernatants obtained from the calcium carbonate suspensions in

Kaj Backfolk; Serge Lagerge; Jarl B. Rosenholm; Dan Eklund

2002-01-01

162

Urinary sodium pump inhibitor raises cytosolic free calcium concentration in rat aorta  

SciTech Connect

We were able to purify two distinct sodium pump inhibitors to homogeneity from human urine based on ({sup 3}H)ouabain-displacing activity from intact human erythrocytes. The polar and less polar compounds were eluted off the C18 reverse-phase column with 18% and 31% acetonitrile, respectively. The polar compound cross-reacted very weakly with specific antidigoxin antibody and lacked a characteristic ultraviolet absorption peak between 190 and 300 nm. The less polar compound showed a prominent digoxinlike immunoreactivity and had an ultraviolet spectrum similar to that of digoxin. We examined the effects of these compounds on cytosolic free calcium concentration in cultured rat vascular smooth muscle cells (A10 cells) using the fluorescent calcium chelator fura-2. Only the polar ouabain-displacing compound caused a significant increase, from 108 +/- 7 to 162 +/- 8 nM (n = 6, p less than 0.01), in cytosolic free calcium concentration in A10 cells. The rise in cytosolic free calcium concentration induced by the polar ouabain-displacing compound tended to be slower in onset and more sustained than that induced by arginine vasopressin. In contrast, ouabain and bufalin had no appreciable effects on cytosolic free calcium concentration in A10 cells. These results suggest that the polar ouabain-displacing compound we isolated from human urine may possess a vasoactive property and may play an important role in the modulation of vascular tone.

Goto, A.; Yamada, K.; Ishii, M.; Yoshioka, M.; Ishiguro, T.; Eguchi, C.; Sugimoto, T. (Univ. of Tokyo (Japan))

1989-06-01

163

Comparative analysis of calcium gluconate and sodium gluconate techniques for the production of gluconic acid by Aspergillus niger  

Microsoft Academic Search

Sodium gluconate and calcium gluconate methods are important techniques available for gluconic acid fermentation. The comparative analysis of these fermentations has been addressed using Aspergillus niger. The techniques are equally influenced by the spores age in slant growth, inoculum level in germination and production media, different levels of Fe, Cu, Zn and Mn. Sodium gluconate method is promising with respect

D. Subba Rao; T. Panda

1993-01-01

164

Energetics of discrete selectivity bands and mutation-induced transitions in the calcium-sodium ion channels family.  

PubMed

We use Brownian dynamics (BD) simulations to study the ionic conduction and valence selectivity of a generic electrostatic model of a biological ion channel as functions of the fixed charge Q(f) at its selectivity filter. We are thus able to reconcile the discrete calcium conduction bands recently revealed in our BD simulations, M0 (Q(f)=1e), M1 (3e), M2 (5e), with a set of sodium conduction bands L0 (0.5e), L1 (1.5e), thereby obtaining a completed pattern of conduction and selectivity bands vs Q(f) for the sodium-calcium channels family. An increase of Q(f) leads to an increase of calcium selectivity: L0 (sodium-selective, nonblocking channel) ? M0 (nonselective channel) ? L1 (sodium-selective channel with divalent block) ? M1 (calcium-selective channel exhibiting the anomalous mole fraction effect). We create a consistent identification scheme where the L0 band is putatively identified with the eukaryotic sodium channel The scheme created is able to account for the experimentally observed mutation-induced transformations between nonselective channels, sodium-selective channels, and calcium-selective channels, which we interpret as transitions between different rows of the identification table. By considering the potential energy changes during permeation, we show explicitly that the multi-ion conduction bands of calcium and sodium channels arise as the result of resonant barrierless conduction. The pattern of periodic conduction bands is explained on the basis of sequential neutralization taking account of self-energy, as Q(f)(z,i)=ze(1/2+i), where i is the order of the band and z is the valence of the ion. Our results confirm the crucial influence of electrostatic interactions on conduction and on the Ca(2+)/Na(+) valence selectivity of calcium and sodium ion channels. The model and results could be also applicable to biomimetic nanopores with charged walls. PMID:24329301

Kaufman, I; Luchinsky, D G; Tindjong, R; McClintock, P V E; Eisenberg, R S

2013-11-01

165

Sodium induces simultaneous changes in cytosolic calcium and pH in salt-tolerant quince protoplasts.  

PubMed

Previous experiments with salt-resistant quince BA29 (Cydonia oblonga cv. Mill.) have shown that this cultivar takes up sodium transiently into the cytosol of shoot protoplasts only in the absence of calcium chloride, or at <1mM calcium chloride. Addition of NaCl > or =100mM to single protoplasts from in vitro-cultivated quince in the presence of 1.0mM calcium induced instant changes in the cytosolic concentrations of calcium and protons. These changes were investigated by use of tetra [acetoxymethyl] esters of the fluorescent stilbene chromophores Fura 2 and bis-carboxyethyl-carboxyfluorescein (BCECF), respectively. The cytosolic Ca(2+) dynamics in the protoplasts were dependent on the concentration of NaCl added. The changes in calcium differed in amplitude and final concentration and were correlated in time mainly with changes in pH. Addition of 100-400mM NaCl to the protoplasts caused an oscillating increase in the cytosolic level of calcium, and then a decrease. Addition of mannitol, of equiosmolar concentration to NaCl, did not increase the cytosolic calcium concentration. Moreover, there was no increase in cytosolic calcium when NaCl was added in the presence of calcium binding ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetra acetic acid (EGTA), or lantan or verapamil, two inhibitors of plasma membrane calcium channels. Therefore, we conclude that, in salt-resistant quince, sodium induces an influx of calcium into the cytosol by plasma membrane calcium channels, and a simultaneous increase in cytosolic pH. Because these changes were obtained in the presence of 1mM calcium in the medium, they were not due to sodium uptake into the cytosol. PMID:19556023

D'Onofrio, Cladio; Lindberg, Sylvia

2009-11-01

166

Physiological characterisation of a pH and calcium-dependent sodium uptake mechanism in the freshwater crustacean, Daphnia magna  

Microsoft Academic Search

Daphnia are highly sensitive to sodium metabolism disruption caused by aquatic acidification and ionoregulatory toxicants, due to their finely balanced ion homeostasis. Nine different water chemistries of varying pH (4, 6 and 8) and calcium concentration (0, 0.5 and 1mmoll -1 ) were used to delineate the mechanism of sodium influx in Daphnia magna. Lowering water pH severely inhibited sodium

Chris N. Glover; Chris M. Wood

2005-01-01

167

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

NASA Astrophysics Data System (ADS)

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 upon hydration of salts containing sodium and potassium ions are explained as a consequence of H-bonds formation and accompanied effects of charge redistribution. Our studies can be useful in searching for the derivatives of dichloroisocyanuric acid revealing higher antimicrobial activity.

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

2006-06-01

168

The regulation of corneal hydration by a salt pump requiring the presence of sodium and bicarbonate ions  

PubMed Central

1. The use of polyacrylamide gel salt bridges enables trans-membrane potentials to be measured to an accuracy of 20 ?V over long periods. 2. The technique is applied to measure electrical potentials across corneal endothelia of rabbits. 3. In de-epithelialized corneas which translocate water, a spontaneous potential of 550 ?V is found across the endothelium (tissue resistance 20 ? cm2). 4. This electrical potential (and water translocation) is reduced to zero when sodium is absent from the Ringer, and by about 80% when bicarbonate ions are absent. Removal of chloride has no such effect. 5. Under a variety of conditions, the potential correlates with the observed translocation of fluid across corneal endothelium. The translocated fluid is shown to be isotonic with sodium in the Ringer and therefore the potential correlates with `active' sodium transport. 6. The potential and water translocation are abolished in the presence of ouabain at concentrations greater than 10-5 M. 7. The potential (lens-side negative) is of the wrong polarity to explain the net sodium transport (into the lens-side) by a sodium ion `pump'. 8. The current does not equal the net sodium flux under short circuit conditions. They differ in magnitude and polarity. 9. A model is proposed where the endothelium `pumps' salt out of the corneal stroma into the aqueous humour. 10. Flux equations are derived for a condition where the membrane (corneal endothelium) separates an ion exchanger (corneal stroma) from free solution (aqueous humour), where the usual relationship for free-free solutions ?? = cs??s does not apply. 11. The model is of use only when the stroma is well stirred. It may be used in whole corneas retaining their epithelium but it may not be used in de-epithelialized corneas. 12. The model predicts that the presence of an `active' salt flux out across the endothelium would create passive water and salt fluxes. The passive water flux would also travel out of the stroma across the endothelium; the passive salt flux would travel, in the opposite direction, into the stroma across the endothelium. 13. The kinetics of the passive water efflux, as a swollen cornea reverts to physiological hydration (the temperature reversal phenomenon) are predicted extremely well if the `active' salt flux is chosen at 33 10-7 m-mole. cm-2 sec-1. 14. The value of the active salt flux which cannot be measured directly is extrapolated to be somewhat greater than 28 10-7 m-moles. cm-2 sec-1; in good agreement with that required by the model to explain the temperature reversal phenomenon. 15. The model is further used to calculate the salt concentration difference across the endothelium (which drives salt passively into the stroma) at various stromal hydrations. 16. When an appropriate salt concentration is applied across the endothelium of de-epithelialized cornea, it generates a potential of the same polarity and similar magnitude to that found across the endothelium of equilibrated whole cornea. The endothelium acts like a cation exchange membrane. 17. Additionally the calculated salt concentration difference across the endothelium correlates well with the measured transendothelial potentials in whole cornea as the corneal hydration varies. 18. It is concluded that the model of an endothelial neutral salt `pump' regulating corneal hydration is self consistent. The spontaneous potential found across the endothelium could be caused by the consequential passive flux of salt in the opposite direction.

Hodson, Stuart

1974-01-01

169

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

NASA Astrophysics Data System (ADS)

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.

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

1984-04-01

170

Role of calcium mobilization in sodium nitroprusside- induced increase of calcium-activated potassium currents in gastric antral circular myocytes of guinea pig1  

Microsoft Academic Search

AIM: To investigate the role of calcium mobilization in the calcium-activated potassium currents (IK(Ca)) increased by sodium nitroprusside (SNP), a nitric oxide (NO) donor, in gastric antral circular myocytes of the guinea pig. METHODS: A perforated patch-clamp technique was used, and the myocytes were isolated by collagenase. RESULTS: SNP 100 mol\\/L significantly increased IK(Ca), and enhanced the spontaneous transient outward

YU Yong-Chun; GUO Hui-Shu; LI Ying; PIAO Lin; LI Lin; LI Zai-Liu; XU Wen-Xie

171

Inhibition of ?-Cell Sodium-Calcium Exchange Enhances Glucose-Dependent Elevations in Cytoplasmic Calcium and Insulin Secretion  

PubMed Central

OBJECTIVE The sodium-calcium exchanger isoform 1 (NCX1) regulates cytoplasmic calcium (Ca2+c) required for insulin secretion in ?-cells. NCX1 is alternatively spliced, resulting in the expression of splice variants in different tissues such as NCX1.3 and -1.7 in ?-cells. As pharmacological inhibitors of NCX1 splice variants are in development, the pharmacological profile of ?-cell NCX1.3 and -1.7 and the cellular effects of NCX1 inhibition were investigated. RESEARCH DESIGN AND METHODS The patch-clamp technique was used to examine the pharmacological profile of the NCX1 inhibitor KB-R7943 on recombinant NCX1.3 and -1.7 activity. Ca2+ imaging and membrane capacitance were used to assess the effects of KB-R7943 on Ca2+c and insulin secretion in mouse and human ?-cells and islets. RESULTS NCX1.3 and -1.7 calcium extrusion (forward-mode) activity was ?16-fold more sensitive to KB-R7943 inhibition compared with cardiac NCX1.1 (IC50s = 2.9 and 2.4 vs. 43.0 ?mol/l, respectively). In single mouse/human ?-cells, 1 ?mol/l KB-R7943 increased insulin granule exocytosis but was without effect on ?-cell glucagon granule exocytosis. KB-R7943 also augmented sulfonylurea and glucose-stimulated Ca2+c levels and insulin secretion in mouse and human islets, although KB-R7943 was without effect under nonstimulated conditions. CONCLUSIONS Islet NCX1 splice variants display a markedly greater sensitivity to pharmacological inhibition than the cardiac NCX1.1 splice variant. NCX1 inhibition resulted in glucose-dependent increases in Ca2+c and insulin secretion in mouse and human islets. Thus, we identify ?-cell NCX1 splice variants as targets for the development of novel glucose-sensitive insulinotropic drugs for type 2 diabetes.

Hamming, Kevin S.C.; Soliman, Daniel; Webster, Nicola J.; Searle, Gavin J.; Matemisz, Laura C.; Liknes, David A.; Dai, Xiao-Qing; Pulinilkunnil, Thomas; Riedel, Michael J.; Dyck, Jason R.B.; MacDonald, Patrick E.; Light, Peter E.

2010-01-01

172

Effect of macromolecules and of sodium dodecyl sulphate upon precipitation of calcium oxalate and phosphate from whole urine.  

PubMed

Different proportions of mixtures of whole urine and its ultrafiltrate were evaporated to 1,250 mosm/kg to study crystal formation of calcium oxalate at pH 5.3 and calcium phosphate at pH 6.8. At both pH values there was a direct linear relationship between proportion of whole urine and crystal formation. When sodium dodecyl sulphate was added to whole urine before evaporation, calcium oxalate and calcium phosphate crystal formation were reduced to 64.3 and 53% respectively of the values of whole urine. This favours the proposition that crystal formation is promoted by polymeric uromucoid. PMID:6719637

Rose, G A; Sulaiman, S

1984-01-01

173

Characterisation of early stage calcium aluminate cement hydration by combination of non-destructive techniques: acoustic emission and X-ray tomography  

Microsoft Academic Search

Techniques that monitor in real time the setting and hardening of calcium aluminate cements (CAC) are now of interest to the engineering community. This paper focuses on the association of two in situ techniques, acoustic emission (AE) and X-rays computed tomography (CT). These non-destructive techniques make it possible to follow the cement hydration in the early stage from a few

T. J Chotard; A Smith; M. P Boncoeur; D Fargeot; C Gault

2003-01-01

174

Endurance Exercise Training Reduces Cardiac Sodium/Calcium Exchanger Expression in Animals Susceptible to Ventricular Fibrillation  

PubMed Central

Aim: Increased sodium/calcium exchanger activity (NCX1, an important regulator of cardiomyocyte cystolic calcium) may provoke arrhythmias. Exercise training can decrease NCX1 expression in animals with heart failure improving cytosolic calcium regulation, and could thereby reduce the risk for ventricular fibrillation (VF). Methods: To test this hypothesis, a 2-min coronary occlusion was made during the last minute of exercise in dogs with healed myocardial infarctions; 23 had VF (S, susceptible) and 13 did not (R, resistant). The animals were randomly assigned to either 10-week exercise training (progressively increasing treadmill running; S n?=?9; R n?=?8) or 10-week sedentary (S n?=?14; R n?=?5) groups. At the end of the 10-week period, the exercise?+?ischemia test provoked VF in sedentary but not trained susceptible dogs. On a subsequent day, cardiac tissue was harvested and NCX1 protein expression was determined by Western blot. Results: In the sedentary group, NCX1 expression was significantly (ANOVA, P?calcium regulation and could thereby reduce the risk for sudden death following myocardial infarction.

Kukielka, Monica; Holycross, Bethany J.; Billman, George E.

2010-01-01

175

Alginate-based pellets prepared by extrusion\\/spheronization: Effect of the amount and type of sodium alginate and calcium salts  

Microsoft Academic Search

Pellets containing microcrystalline cellulose (MCC), a model drug (theophylline) and a range of levels of sodium alginate (i.e., 1050% w\\/w) were prepared by extrusion\\/spheronization. Two types of sodium alginate were evaluated with and without the addition of either calcium acetate or calcium carbonate (0, 0.3, 3 and 10% w\\/w). The effects of amount and type of sodium alginate and calcium

Pornsak Sriamornsak; Jurairat Nunthanid; Manee Luangtana-anan; Yossanun Weerapol; Satit Puttipipatkhachorn

2008-01-01

176

Three types of muscles express three sodium-calcium exchanger isoforms.  

PubMed

The sodium-calcium exchanger (NCX) of plasma membrane is expressed in any animal cell. The specific role of its three isoforms (NCX1-3) is not yet established. Their levels vary considerably during murine postnatal development. In particular, in skeletal muscle, NCX1 expression decreases gradually upon aging while reciprocal changes take place for NCX3. NCX2 expression is restricted to brain and smooth muscles. The data on SDS-gel mobility shifts indicate that all three isoforms undergo Ca2+-dependent conformational changes, and that an exchanger regulatory Ca2+-binding domain interacts directly with mutually exclusive exons A and B inducing two different NCX1 conformations. PMID:17446462

Levitsky, Dmitri O

2007-03-01

177

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

NASA Astrophysics Data System (ADS)

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.

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

2000-05-01

178

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

NASA Astrophysics Data System (ADS)

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.

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

179

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

PubMed

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., CaCl22H2O 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

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

2014-06-11

180

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

PubMed

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

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

2007-06-01

181

Acoustic emission characterisation of calcium aluminate cement hydration at an early stage  

Microsoft Academic Search

In this paper, a new application of the acoustic emission (AE) technique is proposed. This non-destructive and in situ method, widely used in damage characterisation, permits us to follow the cement hydration at the early age from a few minutes to a few hours after mixing. The acoustic emission (AE) signals concerning a pure aluminous cement paste, (water to cement

T. J. Chotard; A. Smith; D. Rotureau; D. Fargeot; C. Gault

2003-01-01

182

principle method based dissolution minerals kinds food materials closed system microwave digestion method measurement sodium potassium calcium magnesium iron zinc phosphorus concentrations ICP-OS.  

EPA Pesticide Factsheets

Did you mean: principle method based dissolution minerals kinds food materials closed system microwave digestion method measurement sodium potassium calcium magnesium iron zinc phosphorus concentrations ICP-OS. ?

183

The Form of Sodium-Calcium Competition at the Frog Myoneural Junction  

PubMed Central

The times required for a steady rate of miniature end-plate potential discharge to be reached in response to changes in extracellular [K+], [Na+], and [Ca++] have been measured. In the presence of 15 mM KCl, Ca++ raises and Na+ lowers the steady-state mepp frequency; but the depressive effect on Na+ is not specific: Li+ can replace Na+ to a large extent. Mepp frequency has been found to depend on the ratio of [Cao++]/[Nao+]. It is assumed that in the steady state, intracellular sodium will change when extracellular sodium is changed. Because both intracellular and extracellular sodium at motor nerve endings affect acetylcholine release, it is proposed that mepp frequency depends on the ratio [Cao] [Nai]2/[Nao]2 Two models are proposed. Firstly, to account for the action of sodium and calcium a carrier is postulated for which Ca++ and Na+ compete. The carrier determines a maximum level of intracellular Ca++ far lower than predicted by the Nernst equation for Ca. Secondly, to account for activation of acetylcholine release by a small influx of Ca++, the ions are presumed to enter the nerve ending in a two stage process through a small intermediate compartment and to act on the acetylcholine release site in this region rather than after entering directly into the cell.

Birks, R. I.; Burstyn, P. G. R.; Firth, D. R.

1968-01-01

184

Compressibility of hydrated and anhydrous sodium silicate-based liquids and glasses, as analogues for natural silicate melts, by Brillouin scattering spectroscopy  

Microsoft Academic Search

A mathematical formalism was tested on compressibility studies of water, before applying it to the high pressure-temperature compressibility studies of hydrated and anhydrous sodium silicate-based liquids and glasses. The hypersonic sound velocity, refractive index and attenuation coefficient obtained using Brillouin light scattering spectroscopy technique were in agreement with literature data. From the measured sound velocities, the pressure dependence of the

Sergey Nikolayevich Tkachev

2005-01-01

185

Cation Hydration Constants by Proton NMR: A Physical Chemistry Experiment.  

ERIC Educational Resources Information Center

Studies the polarization effect on water by cations and anions. Describes an experiment to illustrate the polarization effect of sodium, lithium, calcium, and strontium ions on the water molecule in the hydration spheres of the ions. Analysis is performed by proton NMR. (MVL)

Smith, Robert L.; And Others

1988-01-01

186

Effect of different amounts of sodium intake for 4 months on calcium metabolism in normal and oophorectomized rats.  

PubMed

The effects of different amounts of salt intake on urinary calcium and hydroxyproline (OHP) excretion were studied in oophorectomized (O) and sham-operated (S) rats on normal calcium diet. Groups of O and S rats were given either tap water or 2, 6, or 18 g/liter of NaCl to drink. Urinary excretion of sodium, calcium, and OHP was monitored at 0, 2, and 4 months. Urinary excretion of calcium and OHP increased with increasing salt intake (P < 0.001 by ANOVA) in S and O groups. Oophorectomy did not have any additional effect on calcium or OHP excretion. We conclude that increased salt intake causes increased excretion of calcium and OHP and oophorectomy does not further aggravate the loss. PMID:8256655

Chan, E L; Swaminathan, R

1993-10-01

187

Alendronate sodium hydrate (oral jelly) for the treatment of osteoporosis: review of a novel, easy to swallow formulation  

PubMed Central

Osteoporosis is a skeletal disorder characterized by loss of bone mass, decreased bone strength, and an increased risk of bone fracture. The disease progresses with age, especially in postmenopausal women. Japan is one of the most rapidly aging societies worldwide. Japanese individuals over 65 years of age constituted 23.0% of the population in 2010 and 25.1% to 25.2% as of 2013. The estimated number of people with osteoporosis in Japan is currently 13 million. Bisphosphonates increase bone mineral density by inhibiting osteoclast-mediated bone resorption, thereby reducing the risk of fractures. Alendronate sodium hydrate (alendronate) is a bisphosphonate that potently inhibits bone resorption and is used to treat osteoporosis. Sufficient water is required to take an alendronate oral tablet; insufficient water could result in digestive system diseases, such as esophageal ulceration. Elderly patients with swallowing difficulty may choke on the tablet. Taking a tablet with oral jelly is a method to prevent digestive system disease and reduce the choking hazard. Once-weekly alendronate oral jelly was approved in 2012 by the Ministry of Health, Labour, and Welfare of Japan as the worlds first drug for osteoporosis in a jelly formulation. It consists of a jelly portion and an air portion. The jelly formulation is smoothly discharged by pushing the air portion. Therefore, elderly patients with physical disabilities are able to easily take all of the jelly formulation from the package. In this review, this new formulation of alendronate sodium hydrate (oral jelly) is introduced and discussed in terms of osteoporosis treatment. This new formulation provides an alternative so that patients may select a method of dosing tailored to their preferences. Management of osteoporosis involves assessing fracture risk and preventing fractures. Higher adherence to the treatment of patients with osteoporosis and prevention of osteoporotic fractures are issues to be resolved.

Imai, Kazuhiro

2013-01-01

188

Mercury Atmospheric and Surface Composition Spectrometer Observations of Sodium and Calcium in Mercury's Exosphere During the Second MESSENGER Flyby  

NASA Astrophysics Data System (ADS)

MESSENGER will make its second flyby of Mercury on October 6, 2008, with exospheric sodium and calcium being among several species that will be observed. The observations of sodium begin in the extended tail region ~ 100,000 km in the anti-sunward direction and continue up to ~ 5000 km from the planet. The spacecraft will oscillate back-and-forth about the spacecraft-Sun vector, resulting in scanning the field of view up and down in the Z direction (i.e., north/south) in a Mercury-fixed coordinate system. The extent of the scan in the Z direction will be five Mercury radii above and below the anti-sunward vector at the beginning of the tail sweep and decrease to 3 Mercury radii as the spacecraft nears the planet. Calcium observations begin in the extended tail region ~ 35,000 km behind the planet and continue along with the sodium observations. After the extended tail-region observations, MESSENGER will enter into the shadow of the planet where sodium and calcium nightside observations begin. The spacecraft will be rotated ~ 180 around the spacecraft-Sun vector, resulting in a fan-tail pattern that begins with the field of view pointing in the equatorial plane toward the dawn-side hemisphere of the planet, rotates to the northern polar region, and then continues rotating until pointing in the equatorial plane toward the dusk-side hemisphere of the planet. The field of view will then begin to intersect the planet on the nightside where the observations continue up to the dawn-side terminator region. As the line-of-sight moves out in front of the sub-solar point during the outbound leg of the flyby, dayside observations of sodium begin above a 1000-km tangent height and continue up to several thousand kilometers. A portion of these observations will provide measurements similar to those during the first Mercury flyby and will provide a basis to compare morphological similarities and differences in sodium and calcium between the two sets of observations. Observations performed during this flyby that were not performed previously include measurements of the sodium tail at a much greater distance from the planet, providing additional data on the extent of the sodium tail. Moreover, because calcium was observed on the nightside hemisphere of the planet during the first flyby, this flyby will include a search for calcium in the extended tail region that will provide information concerning the release energy and transport for calcium. Finally, this flyby will search for extended sodium on the dayside exosphere and possibly help to constrain the release processes for sodium on the dayside.

Bradley, E. T.; McClintock, W. E.; Izenberg, N. R.; Killen, R. M.; Kochte, M.; Lankton, M.; Mouawad, N.; Sprague, A. L.; Vervack, R. J.

2008-12-01

189

Magnesium, potassium, sodium and calcium in post-mortem vitreous humour from humans.  

PubMed

Levels of magnesium, potassium, sodium and calcium in post-mortem vitreous humour from human controls, fire fatalities and drowning victims have been determined. The effects of time-related internal changes, external environmental parameters and different causes of death are evaluated. Despite the positive correlation and marked increase of potassium and, to a lesser extent, of magnesium and calcium with the length of the post-mortem interval, individual biological variability severely limits the usefulness of predictions of post-mortem interval based on electrolyte metal data. At best, there is only a 2/3 chance of a prediction being within 12 h of the true value. Vitreous humour metal concentrations are affected by external influences, such as the elevated temperatures of fires which increase the rate of release of intracellular magnesium and potassium. In cases where drowning is suspected, establishment or exclusion of this cause of death is not possible on the basis of vitreous humour electrolyte metal data because of possible post-immersion diffusion across the permeable membrane of the eyeball. It appears, however, that magnesium in salt-water cases and sodium in fresh-water cases are related, albeit erratically, to the length of the immersion period. PMID:3988191

Farmer, J G; Benomran, F; Watson, A A; Harland, W A

1985-01-01

190

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

191

Removal of methyl orange from aqueous solutions through adsorption by calcium aluminate hydrates.  

PubMed

Methyl orange (MO) is a kind of anionic dye and widely used in industry. In this study, tricalcium aluminate hydrates (Ca-Al-LDHs) are used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The resulting products were studied by X-ray diffraction (XRD), infrared spectroscopy (MIR), thermal analysis (TG-DTA) and scanning electron microscope (SEM). The XRD results indicated that the MO molecules were successfully intercalated into the tricalcium aluminate hydrates, with the basal spacing of Ca-Al-LDH expanding to 2.48nm. The MIR spectrum for CaAl-MO-LDH shows obvious bands assigned to the NN, NH stretching vibrations and SO, SO3(-) group respectively, which are considered as marks to assess MO(-) ion intercalation into the interlayers of LDH. The overall morphology of CaAl-MO-LDH displayed a "honey-comb" like structure, with the adjacent layers expanded. PMID:24863763

Zhang, Ping; Wang, Tianqi; Qian, Guangren; Wu, Daishe; Frost, Ray L

2014-07-15

192

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

Microsoft Academic Search

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:

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

2001-01-01

193

Existence of a sodium-induced calcium release mechanism of frog skeletal muscle fibres.  

PubMed Central

1. The electrical and the mechanical activity of isolated frog muscle fibres have been simultaneously recorded in a physiological solution which allows the development of a large tubular sodium current. 2. Under such experimental conditions, fibres develop long-lasting action potentials and strong mechanical responses. 3. In voltage-clamp experiments a slow inward current is revealed for depolarizations higher than +20 mV from the resting potential. This current increases until +40 to +50 mV and then decreases to reverse near +90 mV. The amplitude of the mechanical response increases with the potential to reach an optimum value between +40 and +50 mV and then decreases to stabilize when the depolarization is near +90 mV. 4. In the presence of picrotoxin the slow inward current is reversibly inhibited and the tension-depolarization curve has an S-shape as found in normal physiological conditions. 5. The dependence of a part of the contraction upon the slow inward current is reinforced by the fact that in a 50% sodium solution the amplitude of the current and that of the contraction are reduced in the same proportion. 6. Detubulated fibres failed to generate such a sodium inward current. 7. When sodium ions are replaced by lithium ions a slow inward lithium current develops but it does not induce a mechanical response. 8. Tetracaine reversibly inhibits the current-dependent component of the contraction without affecting the potential-dependent one. 9. It is concluded that the contraction recorded in the present experimental conditions is the sum of two components: one is potential-dependent and the other depends on a sodium-induced calcium release mechanism. Images Plate 1

Potreau, D; Raymond, G

1982-01-01

194

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

SciTech Connect

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.

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

195

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

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Carboxymethylcellulose sodium and/or polyvinylmethylether...Devices § 872.3490 Carboxymethylcellulose sodium and/or polyvinylmethylether...Identification. A carboxymethylcellulose sodium and/or...

2009-04-01

196

Effect of Macromolecules and of Sodium Dodecyl Sulphate upon Precipitation of Calcium Oxalate and Phosphate from Whole Urine  

Microsoft Academic Search

Different proportions of mixtures of whole urine and its ultrafiltrate were evaporated to 1,250 mosm\\/kg to study crystal formation of calcium oxalate at pH 5.3 and calcium phosphate at pH 6.8. At both pH values there was a direct linear relationship between proportion of whole urine and crystal formation. When sodium dodecyl sulphate was added to whole urine before evaporation,

Alan Rose; S. Sulaiman

1984-01-01

197

Effect of ethylenediaminetetraacetic acid (di sodium salt) and aquasoft 330 on crystal growth and morphology of calcium oxalate  

Microsoft Academic Search

Calcium oxalate was synthesized from calcium chloride solution using oxalic acid in the presence of di sodium salt of ethylenediaminetetraacetic acid (EDTA) and commercially available1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aquasoft having chelating value 330 (AQ 330). The experiments were carried out at three different temperatures 60, 80 and 100C. The samples were characterized using scanning electron microscope (SEM), powder X-ray diffraction analysis

P. Vijaya; Shanmukhaprasad Gopi; Aushiq H. Wani; M. V. Rajasekharan; V. K. Subramanian

198

Impact of sodium polyacrylate on the amorphous calcium carbonate formation from supersaturated solution.  

PubMed

A detailed in situ scattering study has been carried out on the formation of amorphous calcium carbonate (ACC) particles modulated by the presence of small amounts of sodium polyacrylate chains. The work is aiming at an insight into the modulation of ACC formation by means of two polyacrylate samples differing in their molecular weight by a factor of 50. The ACC formation process was initiated by an in situ generation of CO(3)(2-) ions via hydrolysis of 10 mM dimethylcarbonate in the presence of 10 mM CaCl(2). Analysis of the formation process by means of time-resolved small-angle X-ray and light scattering in the absence of any additives provided evidence for a monomer addition mechanism for the growth of ACC particles. ACC formation under these conditions sets in after a lag-period of some 350 s. In the presence of sodium polyacrylate chains, calcium polyacrylate aggregates are formed during the lag-period, succeeded by a modulated ACC growth in a second step. The presence of anionic polyacrylate chains changed the shape of the growing particles toward loose and less homogeneous entities. In the case of low amounts (1.5-7.5 mg/L) of the long chain additive with 97 kDa, the size of the aggregates is comparable to the size of the successively formed hybrid particles. No variation of the lag-period has been observed in this case. Use of the short chain additive with 2 kDa enabled increase of the additive concentration up to 100 mg/L and resulted in a significant increase of the lag-period. This fact, together with the finding that the resulting hybrid particles remained stable in the latter case, identified short chain sodium polyacrylates as more efficient modulators than long chain polyacrylates. PMID:22256962

Liu, J; Pancera, S; Boyko, V; Gummel, J; Nayuk, R; Huber, K

2012-02-21

199

Salts of aliphatic carboxylic acids: Raman spectra and ion pairing in hydrothermal solutions containing sodium and calcium acetates  

Microsoft Academic Search

A 2.0 molal solution of sodium acetate and 0.1, 0.5, and 1.0 molal solutions of calcium acetate were investigated by Raman spectroscopy from 22 to 400C at 1000 and 2000 bar. Experiments were performed in a special hydrothermal pressure vessel fitted with conical diamond windows. In the case of the sodium acetate solution, perturbations of the internal vibrational modes of

John D Frantz

2000-01-01

200

Calcium  

MedlinePLUS

... calcium. Veggies. You'll also find calcium in broccoli and dark green, leafy vegetables (especially collard and ... of calcium such as dark green, leafy vegetables, broccoli, chickpeas, and calcium-fortified products, including orange juice, ...

201

X-ray diffraction: a powerful tool to probe and understand the structure of nanocrystalline calcium silicate hydrates  

PubMed Central

X-ray diffraction (XRD) patterns were calculated and compared to literature data with the aim of investigating the crystal structure of nanocrystalline calcium silicate hydrates (C-S-H), the main binding phase in hydrated Portland cement pastes. Published XRD patterns from C-S-H of Ca/Si ratios ranging from ??0.6 to ??1.7 are fully compatible with nanocrystalline and turbostratic tobermorite. Even at a ratio close or slightly higher than that of jennite (Ca/Si = 1.5) this latter mineral, which is required in some models to describe the structure of C-S-H, is not detected in the experimental XRD patterns. The 001 basal reflection from C-S-H, positioned at ??13.5? when the C-S-H structural Ca/Si ratio is low (< 0.9), shifts towards smaller d values and sharpens with increasing Ca/Si ratio, to reach ??11.2? when the Ca/Si ratio is higher than 1.5. Calculations indicate that the sharpening of the 001 reflection may be related to a crystallite size along c* (i.e. a mean number of stacked layers) increasing with the C-S-H Ca/Si ratio. Such an increase would contribute to the observed shift of the 001 reflection, but fails to quantitatively explain it. It is proposed that the observed shift could result from interstratification of at least two tobermorite-like layers, one having a high and the other a low Ca/Si ratio with a basal spacing of 11.3 and 14?, respectively.

Grangeon, Sylvain; Claret, Francis; Linard, Yannick; Chiaberge, Christophe

2013-01-01

202

Synthesis and hydration of calcium sulfoaluminate-belite cements with varied phase compositions  

Microsoft Academic Search

The production of portland cement is energy intensive and contributes significantly to greenhouse gas emissions. One method\\u000a of reducing the environmental impact of concrete production is the use of an alternative binder, such as calcium sulfoaluminate-belite\\u000a (CSAB) cement. The relatively low lime requirement of CSAB cement compared to portland cement reduces energy consumption and\\u000a carbon dioxide emissions from cement production.

Irvin A. ChenMaria; Maria C. G. Juenger

2011-01-01

203

Comparison of serum fluoride levels after administration of monofluorophosphate-calcium carbonate or sodium fluoride: differences in peak serum concentrations  

Microsoft Academic Search

Fluoride salts are widely used in Europe in the treatment of established osteoporosis with crush fractures for their ability to increase trabecular bone mass. However, in the United States fluorides are still regarded as an experimental drug. In a prospective, randomized study we compared the fluoride pharmacokinetics of enteric-coated sodium fluoride and disodium monofluorophosphate calcium carbonate (MFP-Ca) over the period

L. Erlacher; H. Teufelsbauer; P. Bernecker; P. Pietschmann; M. Weissel

1994-01-01

204

DELIQUESCENCE BEHAVIOR AND CHEMICAL STABILITY OF VITAMIN C FORMS (ASCORBIC ACID, SODIUM ASCORBATE, AND CALCIUM ASCORBATE) AND BLENDS  

Microsoft Academic Search

The stability and type of vitamin C added to foods is important for enhancing product quality, label claims, and shelf-life. To improve understanding of stability, the effects of deliquescence, storage RH, formulation, and addition of ascorbyl palmitate and dehydroascorbic acid on degradation of vitamin C at 25C were studied. Individual vitamin C forms (ascorbic acid, sodium and calcium ascorbate) and

Ashley N. Hiatt; Mario G. Ferruzzi; Lynne S. Taylor; Lisa J. Mauer

2010-01-01

205

Formation of inositol phosphates in synaptoneurosomes of guinea pig brain: stimulatory effects of receptor agonists, sodium channel agents and sodium and calcium ionophores.  

PubMed

Carbamylcholine, norepinephrine, histamine and glutamate stimulated the formation of [3H]inositol phosphates in [3H]inositol-labelled synaptoneurosomes obtained from the cortex, striatum and hippocampus of the guinea pig. Synaptoneurosomes prepared from the cerebellum did not respond to receptor agonists. Agents that enhance the influx of sodium ions through voltage-sensitive channels, such as batrachotoxin, scorpion venom and pumiliotoxin B, or a sodium ionophore, monensin, stimulated the formation of [3H]inositol phosphates in synaptoneurosomes from all four regions of the brain. Neither calcium channel blockers nor receptor antagonists reduced the responses to batrachotoxin. Ionomycin, a calcium ionophore, also stimulated the formation of [3H]inositol phosphates in synaptoneurosomes from all four regions of the brain. A phorbol ester inhibited the formation of [3H]inositol phosphates, elicited by either receptor agonists or by sodium channel agents. The major [3H]inositol-labelled lipid in the synaptoneurosomes was phosphatidylinositol as analyzed by thin layer chromatography. While the hydrolysis of phosphatidylinositol elicited by carbamylcholine resulted in an increase of lipid-labelling with [3H]inositol, sodium channel agents caused a decrease in the incorporation of [3H]inositol. The results indicate that intracellular sodium may have a regulatory role in the turnover of phosphatidylinositol, and that, unlike the receptor-mediated responses, this regulation is present in all regions of the brain. PMID:2451187

Gusovsky, F; Daly, J W

1988-01-01

206

Effect of temperature on the microstructure of calcium silicate hydrate (C-S-H)  

SciTech Connect

Temperature affects the properties of concrete through its effect on the hydration of cement and its associated microstructural development. This paper focuses on the modifications to C-S-H induced by isothermal curing between 5 and 60 C. The results show that as the temperature increases (within the range studied) the C/S ratio of C-S-H changes only slightly, with a higher degree of polymerisation of silicate chains, but there is a significant decrease in its bound water content and an increase of apparent density of 25%. This increase seems to come from a different packing of C-S-H at the nanoscale. As a consequence of these changes, the microstructure of the cement paste is much coarser and porous, which explains the lower final strengths obtained by curing at elevated temperatures. -- Highlights: C-S-H structure studied at the atomic level Multiple analytical techniques used Studies conducted at temperatures above and below normal temperatures.

Gallucci, E., E-mail: gallucci.emmanuel@ch.sika.com; Zhang, X.; Scrivener, K.L.

2013-11-15

207

No Calcium-Fluoride-Like Deposits Detected in Plaque Shortly after a Sodium Fluoride Mouthrinse  

PubMed Central

Plaque calcium-fluoride-like (CaF2-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 ?g/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF2-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitates containing known amounts of CaF2-like deposits. Nearly identical fluoride concentrations were found in both plaque aliquots. The extraction of the CaF2-like precipitates formed in vitro removed more than 80% of these deposits. The results suggest that either CaF2-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF2-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses.

Vogel, G.L.; Tenuta, L.M.A.; Schumacher, G.E.; Chow, L.C.

2010-01-01

208

Effect of biomedical organic compounds on the setting reaction of calcium phosphates  

Microsoft Academic Search

In the present study, the effect of biomedical organic compounds (starch, sodium alginate, chitosan and gelatin) on the hydration of calcium phosphates was studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and XPS analysis. Amorphous calcium phosphate (ACP) was prepared by a mechanochemical route and mixed with biomedical organic compounds. A solidification reaction occurred between ACP and dicalcium phosphate

Tao Yu; Jiandong Ye; Chengying Gao; Long Yu; Yingjun Wang

2010-01-01

209

Use of calcium caseinate in association with lecithin for masking the bitterness of acetaminophen--comparative study with sodium caseinate.  

PubMed

Owing to a variety of structural and functional properties, milk proteins are steadily studied for food and pharmaceutical applications. In the present study, calcium caseinate in association with lecithin was firstly investigated in order to encapsulate the acetaminophen through spray-drying for taste-masking purpose for pediatric medicines. A 2(4)-full factorial design revealed that the spray flow, the calcium caseinate amount and the lecithin amount had significant effects on the release of drug during the first 2 min. Indeed, increasing the spray flow and/or the calcium caseinate amount led to increase the released amount, whereas increasing the lecithin amount decreased the released amount. The "interaction" between the calcium caseinate amount and the lecithin amount was also shown to be statistically significant. The second objective was to compare the efficiency of two caseinate-based formulations, i.e. sodium caseinate and calcium caseinate, on the taste-masking effect. The characteristics of spray-dried powders determined by SEM and DSC were shown to depend on the caseinate/lecithin proportion rather than the type of caseinate. Interestingly, calcium caseinate-based formulations were found to lower the released amount of drug during the early time to a higher extent than sodium caseinate-based formulations, which indicates better taste-masking efficiency. PMID:24016744

Hoang Thi, Thanh Huong; Lemdani, Mohamed; Flament, Marie-Pierre

2013-11-18

210

Differential Hippocampal Protection when Blocking Intracellular Sodium and Calcium Entry during Traumatic Brain Injury in Rats  

PubMed Central

Abstract This study investigated the contributions of the reverse mode of the sodium-calcium exchanger (NCX) and the type 1 sodium-proton antiporter (NHE-1) to acute astrocyte and neuronal pathology in the hippocampus following fluid percussion traumatic brain injury (TBI) in the rat. KB-R7943, EIPA, or amiloride, which respectively inhibit NCX, NHE-1, or NCX, NHE-1, and ASIC1a (acid-sensing ion channel type 1a), was infused intraventricularly over a 60-min period immediately prior to TBI. Astrocytes were immunostained for glial fibrillary acidic protein (GFAP), and degenerating neurons were identified by Fluoro-Jade staining at 24?h after injury. Stereological analysis of the CA2/3 sub-regions of the hippocampus demonstrated that higher doses of KB-R7943 (2 and 20 nmoles) significantly reduced astrocyte GFAP immunoreactivity compared to vehicle-treated animals. EIPA (2200 nmoles) did not alter astrocyte GFAP immunoreactivity. Amiloride (100 nmoles) significantly attenuated the TBI-induced acute reduction in astrocyte GFAP immunoreactivity. Of the three compounds examined, only amiloride (100 nmoles) reduced hippocampal neuronal degeneration assessed with Fluoro-Jade. The results provide additional evidence of acute astrocyte pathology in the hippocampus following TBI, while suggesting that activation of NHE-1 and the reverse mode of NCX contribute to both astrocyte and neuronal pathology following experimental TBI.

Zhao, Xueren; Gorin, Fredric A.; Berman, Robert F.

2008-01-01

211

EFFECTS OF SODIUM AND CALCIUM IN LIGNITE ON THE PERFORMANCE OF ACTIVATED CARBON PRODUCTS  

SciTech Connect

New federal drinking water regulations have been promulgated to restrict the levels of disinfection by-products (DBPs) in finished public water supplies. DBPs are suspected carcinogens and are formed when organic material is partially oxidized by disinfectants commonly used in the water treatment industry. Additional federal mandates are expected in the near future that will also affect public water suppliers with respect to DBPs. These new federal drinking water regulations may require public water suppliers to adjust treatment practices or incorporate additional treatment operations into their existing treatment trains. Many options have been identified, including membrane processes, granular activated carbon, powered activated carbon (PAC), enhanced coagulation and/or softening, and alternative disinfectants (e.g., chlorine dioxide, ozone, and chloramines). Of the processes being considered, PAC appears to offer an attractive benefit-to-cost advantage for many water treatment plants, particularly small systems (those serving fewer than 10,000 customers). PAC has traditionally been used by the water treatment industry for the removal of compounds contributing to taste and odor problems. PAC also has the potential to remove naturally occurring organic matter (NOM) from raw waters prior to disinfection, thus controlling the formation of regulated DBPs. Many small water systems are currently using PAC for taste and odor control and have the potential to use PAC for controlling DBPs. Activated carbons can be produced from a variety of raw materials, including wood, peat, coconut husks, and numerous types of coal. The Energy & Environmental Research Center (EERC) has been working on the development of a PAC product to remove NOM from surface water supplies to prevent the formation of carcinogenic DBPs during chlorination. During that study, the sodium and calcium content of the lignites showed a significant effect on the sorption capacity of the activated carbon product. As much as a 130% increase in the humic acid sorption capacity of a PAC produced from a high-sodium-content lignite was observed. We hypothesize that the sodium and calcium content of the coal plays a significant role in the development of pore structures and pore-size distribution, ultimately producing activated carbon products that have greater sorption capacity for specific contaminants, depending on molecular size.

Edwin S. Olson; Kurt E. Eylands; Daniel J. Stepan

2001-12-01

212

The Crystal Structure of Hydrated Sodium Aluminate, NaAlO 2 5\\/4H 2O, and Its Dehydration Product  

Microsoft Academic Search

The crystal structure of hydrated sodium aluminate, NaAlO2 5\\/4H2O, has been determined ab initio from synchrotron powder diffraction data. The compound crystallizes in the acentric primitive tetragonal space group P4? 21m, with a = 10.53396(4) and c = 5.33635(3) at 27C, and Z = 8. The structure consists of single layers parallel to (001) made of corner-sharing

James A. Kaduk; Shiyou Pei

1995-01-01

213

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

Microsoft Academic Search

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

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

2006-01-01

214

Bones and Crohn's: No benefit of adding sodium fluoride or ibandronate to calcium and vitamin D  

PubMed Central

AIM: To compare the effect of calcium and cholecalciferol alone and along with additional sodium fluoride or ibandronate on bone mineral density (BMD) and fractures in patients with Crohns disease (CD). METHODS: Patients (n =148) with reduced BMD (T-score < -1) were randomized to receive cholecalciferol (1000 IU) and calcium citrate (800 mg) daily alone(group A, n = 32) or along with additional sodium fluoride (25 mg bid) (group B, n = 62) or additional ibandronate (1 mg iv/3-monthly) (group C, n = 54). Dual energy X-ray absorptiometry of the lumbar spine (L1-L4) and proximal right femur and X-rays of the spine were performed at baseline and after 1.0, 2.25 and 3.5 years. Fracture-assessment included visual reading of X-rays and quantitative morphometry of vertebral bodies (T4-L4). RESULTS: One hundred and twenty three (83.1%) patients completed the first year for intention-to-treat (ITT) analysis. Ninety two (62.2%) patients completed the second year and 71 (47.8%) the third year available for per-protocol (PP) analysis. With a significant increase in T-score of the lumbar spine by +0.28 0.35 [95% confidence interval (CI): 0.162-0.460, P < 0.01], +0.33 0.49 (95% CI: 0.109-0.558, P < 0.01), +0.43 0.47 (95% CI: 0.147-0.708, P < 0.01) in group A, +0.22 0.33 (95% CI: 0.125-0.321, P < 0.01); +0.47 0.60 (95% CI: 0.262-0.676, P < 0.01), +0.51 0.44 (95% CI: 0.338-0.682, P < 0.01) in group B and +0.22 0.38 (95% CI: 0.111-0.329, P < 0.01), +0.36 0.53 (95% CI: 0.147-0.578, P < 0.01), +0.41 0.48 (95% CI: 0.238-0.576, P < 0.01) in group C, respectively, during the 1.0, 2.25 and 3.5 year periods (PP analysis), no treatment regimen was superior in any in- or between-group analyses. In the ITT analysis, similar results in all in- and between-group analyses with a significant in-group but non-significant between-group increase in T-score of the lumbar spine by 0.38 0.46 (group A, P < 0.01), 0.37 0.50 (group B, P < 0.01) and 0.35 0.49 (group C, P < 0.01) was observed. Follow-up in ITT analysis was still 2.65 years. One vertebral fracture in the sodium fluoride group was detected. Study medication was safe and well tolerated. CONCLUSION: Additional sodium fluoride or ibandronate had no benefit over calcium and cholecalciferol alone in managing reduced BMD in CD.

Klaus, Jochen; Reinshagen, Max; Herdt, Katharina; Schroter, Christoph; Adler, Guido; von Boyen, Georg BT; von Tirpitz, Christian

2011-01-01

215

Removal of trichloroethylene from soil using the hydration of calcium oxide.  

PubMed

Quicklime addition to soil at a remediation site was observed to sufficiently reduce TCE levels, but the cause of the removal could not be confirmed with the field data collected. Potential mechanisms for CaO treatment of trichloroethylene (TCE) in soil include degradation and volatilization. Since earlier studies found TCE degradation to occur during the hydration of CaO under conditions where volatilization was limited, research was conducted on mechanisms of TCE removal from soil by CaO application under conditions where volatilization was allowed to occur. TCE volatilization in soil treated with 0%, 5%, 10%, and 20% CaO doses was measured in experiments where the degree of volatilization could be tracked. The total TCE removal from soil spiked with TCE at CaO doses from 5% to 20% ranged from 97% to 99% of the initial TCE mass. Volatilization accounted for 64.4-92.5% of the TCE removal, with unrecovered TCE and TCE degradation accounting for the remaining fraction. The greater heat encountered with higher CaO doses helped minimize obstacles to TCE volatilization, such as high soil organic and clay content. Treatment with a 20% CaO dose, however, led to the formation of byproducts such as dichloroacetylene. TCE degradation to dichloroacetylene at the 20% CaO dose ranged from 2.7% to 6.4% of the initial TCE. Volatilization was concluded to be the dominant process for TCE removal from soil during CaO treatment. PMID:21414713

Ko, Jae Hac; Musson, Steve; Townsend, Timothy

2011-07-01

216

Belite cements: modifications of calcium silicate hydrate (C-S-H) gel by alkaline hydrothermal activation  

SciTech Connect

The C-S-H gel of two types of fly ash belite cements (FABC) are studied at a nanoscale (1 to 100 nm (39.4 to 3940 nin.)) by means of the specific surface area and pore-size distribution, which were measured by the sorption isotherms of nitrogen gas and the BET method. The two belite cements were fabricated by the hydro-thermal-calcination route of Class C fly ash in NaOH 1M solution (FABC-2-N) and demineralized water (FABC-2-W). Two differentiated zones in the pore-size distribution of the C-S-H gel at similar to 12 and similar to 3 nm (similar to 473 and similar to 118 nin.) with different influences in the mechanical strength were produced. The proportion of both zones depends on the age of hydration and type of belite cement. At early ages, the C-S-H gel of FABC-2-N develops both zones in a greater proportion than those of FABC-2-W. At later ages, the behavior is opposite: the C-S-H gel of FABC-2-W develops high proportion of pores of 3 nin (118 nm.) of diameter. Important quantitative correlations were found among these nanostructure characteristics of the C-S-H gel and macrostructural engineering property.

Guerrero, A.; Goni, S.; Dolado, J.S. [CSIC, Eduardo Torroja Inst. Construct. Sci., Madrid (Spain)

2009-03-15

217

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

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.

Freidin, C.

1999-11-01

218

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

PubMed Central

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

Kennedy, H J; Thomas, R C

1995-01-01

219

The temperature dependence of the exchange enthalpy of calcium and sodium ions on polymethacrylic and polyacrylic cationites  

NASA Astrophysics Data System (ADS)

The influence of temperature on the exchange of calcium and sodium ions from solutions of 2.3 2.8 g-equiv/l concentrations on KB-2e4 gel polyacrylic cationite, KB-4P2 and KB-4 gel polymethacrylic cationites, and Purolite C104 polyacrylic cationite was studied over the temperature range 273 400 K. It was shown that, simultaneously with a substantial increase in selectivity with respect to calcium ions, the differential enthalpy of the ion exchange reaction increased linearly on all polyacrylic and polymethacrylic cationites as the temperature grew.

Ivanov, V. A.; Gavlina, O. T.; Ilyukhina, E. A.; Gorshkov, V. I.

2007-11-01

220

Molecular dynamics in hydrated sodium alginate by quasielastic and elastic neutron scattering  

NASA Astrophysics Data System (ADS)

We present the QENS measurements result obtained at LLB using the MIBEMOL-TOF neutron spectrometer devoted to the study of sodium alginate-heavy water molecular dynamics behaviour, in an observation time range of 15 ns-1 ps. The data analysis allowed us to reveal the molecular motion manner of the two components of the system, as well as the dynamical parameters associated with various types of diffusion performed by water molecules constrained to move in the confined spaces created by the biopolymer chains. The various molecular groups belonging to these chains perform, at their turn, rotational diffusion motions in restricted spaces that can be described in terms of jump diffusion in a spherical potential model. From the elastic intensity we have calculated the elastic incoherent structure factor, EISF which reveals a molecular diffusion motion in spherical potential. At the same time we have obtained the mean square displacement (MSD), which is an increasing function of temperature presenting two slope changes at 145 and 185 K, respectively. These transition temperatures were associated with the molecular rotations release and translation outset, respectively.

Tripadus, V.; Zanotti, J. M.; Statescu, M.; Constantinescu, O.; Mitra, S.; Aranghel, D.

2009-11-01

221

Sodium is the leading dietary factor associated with urinary calcium excretion in Hong Kong Chinese adults.  

PubMed

We conducted a cross-sectional population-based study comprising 1010 Hong Kong Chinese (500 men and 510 women) aged 25-74 years during 1995-6. The study examined the important dietary, lifestyle and anthropometric factors associated with urinary calcium excretion. Dietary intakes were assessed by means of food frequency questionnaire. Spot urine was collected to measure the urinary excretion profiles of calcium (Ca), sodium (Na), potassium (K) and creatinine (Cr). When expressed as ratios of cations to urinary Cr, significant relationships were noted between urinary Ca and Na (r: approximately 0.6), and between urinary Ca and K (r: 0.17-0.21). Stepwise multiple linear regression analyses were carried out separately in men and women aged below and above 50 years. We found that urinary Na/Cr was the leading independent factor associated with urinary Ca/Cr in all four age and sex groups. It accounted for 22% of urinary Ca/Cr variations in women aged below 50 years, and 35-43% in the other three age and sex groups. We estimated that urinary Ca excretion increased by about 1.4 (range 1.37-1.43) mmol per 100 mmol increase in urinary Na. Except in men aged 50 years and over, urinary K/Cr was inversely associated with urinary Ca/Cr in all groups. Age was independently and positively associated with urinary Ca/ Cr in subjects aged below 50 years. We did not observe any significant relation between urinary Ca/Cr and dietary protein, phosphorus, alcohol drinking and smoking. In conclusion, we found that urinary Na/Cr, but not dietary protein, Ca or phosphorus, is the most important factor influencing urinary Ca/Cr excretion in our population. Urinary K is a potential factor for Ca conservation. PMID:11605737

Ho, S C; Chen, Y M; Woo, J L; Leung, S S; Lam, T H; Janus, E D

2001-01-01

222

Erosion protection by calcium lactate/sodium fluoride rinses under different salivary flows in vitro.  

PubMed

This study investigated the effect of a calcium lactate prerinse on sodium fluoride protection in an in vitro erosion-remineralization model simulating two different salivary flow rates. Enamel and dentin specimens were randomly assigned to 6 groups (n = 8), according to the combination between rinse treatments - deionized water (DIW), 12 mM NaF (NaF) or 150 mM calcium lactate followed by NaF (CaL + NaF) - and unstimulated salivary flow rates - 0.5 or 0.05 ml/min - simulating normal and low salivary flow rates, respectively. The specimens were placed into custom-made devices, creating a sealed chamber on the specimen surface connected to a peristaltic pump. Citric acid was injected into the chamber for 2 min, followed by artificial saliva (0.5 or 0.05 ml/min) for 60 min. This cycle was repeated 4/day for 3 days. Rinse treatments were performed daily 30 min after the 1st and 4th erosive challenges, for 1 min each time. Surface loss was determined by optical profilometry. KOH-soluble fluoride and structurally bound fluoride were determined in specimens at the end of the experiment. Data were analyzed by 2-way ANOVA and Tukey tests (? = 0.05). NaF and CaL + NaF exhibited significantly lower enamel and dentin loss than DIW, with no difference between them for normal flow conditions. The low salivary flow rate increased enamel and dentin loss, except for CaL + NaF, which presented overall higher KOH-soluble and structurally bound fluoride levels. The results suggest that the NaF rinse was able to reduce erosion progression. Although the CaL prerinse considerably increased F availability, it enhanced NaF protection against dentin erosion only under hyposalivatory conditions. PMID:24480975

Borges, Alessandra B; Scaramucci, Tas; Lippert, Frank; Zero, Domenick T; Hara, Anderson T

2014-01-01

223

Final Report On the Safety Assessment of Glycolic Acid, Ammonium, Calcium, Potassium, and Sodium Glycolates, Methyl, Ethyl, Propyl, and Butyl Glycolates, and Lactic Acid, Ammonium, Calcium, Potassium, Sodium, and Tea-Lactates, Methyl, Ethyl, Isopropyl, and Butyl Lactates, and Lauryl, Myristyl, and Cetyl Lactates  

Microsoft Academic Search

This report provides a review of the safety of Glycolic Acid, Ammonium, Calcium, Potassium, and Sodium Glycolates, Methyl, Ethyl, Propyl, and Butyl Glycolates, Lactic Acid, Ammonium, Calcium, Potassium, Sodium, and TEA-Lactates, and Lauryl, Myristyl, and Cetyl Lactates. These ingredients belong to a group known as alpha-hydroxy acids (AHAs). Products containing these ingredients may be for consumer use, salon use, or

F. A. Andersen

1998-01-01

224

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

SciTech Connect

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?

Schumaker, Karen S [Professor] [Professor

2013-10-24

225

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

Microsoft Academic Search

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

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

2005-01-01

226

Equilibrium studies of sodium-ammonium potassium-ammonium, and calcium-ammonium exchanges on clinoptilolite zeolite  

SciTech Connect

Forward and reverse ion-exchange isotherms for the binary sodium-ammonium, potassium-ammonium, and calcium-ammonium systems on clinoptilolite have been measured in aqueous solutions at a total concentration of 0.1 equiv/dm{sup 3} and at 298 K. Prior to exchange experiments it was attempted to prepare homoionic forms of the zeolite by exhaustive treatments with appropriate salt solutions of cations. With no binary exchanges, full replacement of the cation by the ammonium ion is observed, which conflicts with some earlier work on clinoptilolite. Despite the observed partial exchange levels, clinoptilolite shows a very high preference for ammonium ion over sodium and calcium but not over potassium. Thermodynamic values for the exchanges were calculated and compared with data in the literature. Both the selectivity and thermodynamic affinity sequence, in agreement with previous work reported in the literature, are K{sup +} > NH{sub 4}{sup +} > Na{sup +} > Ca{sup 2+}.

Jama, M.A.; Yuecel, H. (Middle East Technical Univ., Ankara (Turkey))

1989-12-01

227

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

PubMed

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

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

2009-01-01

228

[Progress in the physiological and pathophysiological functions of sodium calcium exchangers].  

PubMed

Sodium calcium exchanger (NCX), which is widely expressed in the plasma membrane, mitochondrial membrane and secretory vesicles in diverse kinds of cells, belongs to a type of cation translocators. NCX works in two modes, the forward mode and reverse mode, to regulate the intracellular Ca(2+) concentration bi-directionally. In the forward mode, NCX carries Ca(2+) out of the cell against its electrochemical gradients coupled to the influx of Na+ down its electrochemical gradients; alternatively, Ca(2+) enters through the reverse mode of NCX, and Na+ is carried out of the cell. Exactly through the two-way modes, NCX can regulate intracellular Ca(2+) concentration fleetly and accurately, and plays a critical role in a series of physiological processes including intracellular signal transduction, growth and development of cells, excitation and its coupled functions of excitable cells. NCX are acknowledged to be involved in myofiber contraction, neurotransmission, migration and differentiation of neurogliocyte, activation of immune cells, secretion of cytokines and hormones etc. Moreover, abnormal activation of the reverse mode of NCX plays a vital role in many pathological processes including cell apoptosis, ischemia-reperfusion injury, insulin secretion, tumor etc. Here we reviewed the research status about the NCX's participation in some physiological and pathophysiological processes, so as to provide comprehensive understanding about its functions. PMID:24777416

Su, Jun-Jie; Qi, Ge-Yao; Dang, Xiao-Zhi; Yang, Nian; Zhang, Jun

2014-04-25

229

Interactions between mica surfaces in sodium polyacrylate solutions containing calcium ions  

SciTech Connect

Polyacrylic acid (PAA) and its salts find use in a number of different applications, such as in fluids for secondary oil recovery, as dispersing agents for mineral suspensions in, for example, ceramic and paper coating applications, and as flocculants for waste-water treatment. The forces acting between negatively charged muscovite mica surfaces immersed in solutions containing sodium polyacrylate (NaPAA) have been studied. No evidence for PAA adsorption in the absence of calcium ions in the solution was found. However, at a CaCl[sub 2] concentration of about 3 [times] 10[sup [minus]3] M a layer of PAA adsorbed on each surface. At large separations, the forces between the PAA-coated surfaces were dominated by repulsive double-layer forces. At separations below 50--80 [angstrom], depending on the solution conditions, an attractive force in excess of the van der Waals attraction was observed. The adhesion force between the layers was 7-8 mN / m at pH 6 and increased somewhat with increasing pH to about 9 mN/m at pH 10. The authors argue that both the long-range attraction and the adhesion force primarily are due to COO[sup [minus

Berg, J.M.; Claesson, P.M. (Royal Inst. of Tech., Stockholm (Sweden). Dept of Physical Chemistry); Neuman, R.D. (Auburn Univ., AL (United States). Dept. of Chemical Engineering)

1993-11-01

230

Calcium, magnesium, potassium and sodium intakes in Japanese children aged 3 to 5 years.  

PubMed

The present study aimed to evaluate in preschool children the intakes of Ca, Mg that possibly affect health and tooth formation and the intakes of K and Na that may affect lifestyle-related diseases. Information on dietary intake was collected from 90 preschool children (15 boys and 15 girls each in the 3-, 4- and 5-year old groups) on 3 separate days in the school fiscal year 1999 (April 1999 to March 2000) by the duplicate-diet technique. The Ca, Mg, K, and Na concentrations were determined by atomic absorption spectrometry using wet-ashed samples. The medians of mean daily intakes of Ca, Mg, K and Na in 3- to 5-year-old children were 432 mg, 110 mg, 1.18 g and 1.60 g, respectively, and no significant differences with regard to gender were observed. Seasonal varia-tion of intake was seen for each mineral. Calcium intake in most preschool children did not meet adequate intake (AI), probably due to low intakes of milk and dairy products in Japan. Magnesium intake was below the estimated average requirement (EAR) in 13.3% of the subjects, while the K intake met the AI. Sodium intake in a quarter of preschool children exceeded the tentative dietary goal. We concluded that in Japanese children aged 3-5 years; Ca intake is low, Na intake is high, and K intake is adequate, but some children could be at risk for Mg deficiency. PMID:18818164

Shibata, Tomiko; Murakami, Taeko; Nakagaki, Haruo; Narita, Naoki; Goshima, Miho; Sugiyama, Tomoko; Nishimuta, Mamoru

2008-01-01

231

Transuranium removal from Hanford high level waste simulants using sodium permanganate and calcium  

NASA Astrophysics Data System (ADS)

Plutonium and americium are present in the Hanford high level liquid waste complexant concentrate (CC) due to the presence of complexing agents including di-(2-ethylhexyl) phosphoric acid (D2EHPA), tributylphosphate (TBP), hydroxyethylene diamine triacetic acid (HEDTA), ethylene diamine tetraacetic acid (EDTA), citric acid, glycolic acid, and sodium gluconate. The transuranic concentrations approach 600 nCi/g and require processing prior to encapsulation into low activity glass. BNFL's (British Nuclear Fuels Limited's) original process was a ferric co-precipitation method based on earlier investigations by Herting and Orth, et al. Furthermore, flocculation and precipitation are widely used for clarification in municipal water treatment. Co-precipitation of Np, Am, and Pu with ferric hydroxide is also used within an analytical method for the sum of those analytes. Tests to evaluate BNFL's original precipitation process indicated the measured decontamination factors (DFs) and filter fluxes were too low. Therefore, an evaluation of alternative precipitation agents to replace ferric ion was undertaken. Agents tested included various transition metals, lanthanide elements, uranium species, calcium, strontium, and permanganate. .

Wilmarth, W. R.; Rosencrance, S. W.; Nash, C. A.; Fonduer, F. F.; Diprete, D. P.; Diprete, C. C.

2000-07-01

232

Polyunsaturated fatty acids modulate sodium and calcium currents in CA1 neurons.  

PubMed Central

Recent evidence indicates that long-chain polyunsaturated fatty acids (PUFAs) can prevent cardiac arrhythmias by a reduction of cardiomyocyte excitability. This was shown to be due to a modulation of the voltage-dependent inactivation of both sodium (INa) and calcium (ICa) currents. To establish whether PUFAs also regulate neuronal excitability, the effects of PUFAs on INa and ICa were assessed in CA1 neurons freshly isolated from the rat hippocampus. Extracellular application of PUFAs produced a concentration-dependent shift of the voltage dependence of inactivation of both INa and ICa to more hyperpolarized potentials. Consequently, they accelerated the inactivation and retarded the recovery from inactivation. The EC50 for the shift of the INa steady-state inactivation curve was 2.1 +/- 0.4 microM for docosahexaenoic acid (DHA) and 4 +/- 0.4 microM for eicosapentaenoic acid (EPA). The EC50 for the shift on the ICa inactivation curve was 2.1 +/- 0.4 for DHA and > 15 microM for EPA. Additionally, DHA and EPA suppressed both INa and ICa amplitude at concentrations > 10 microM. PUFAs did not affect the voltage dependence of activation. The monounsaturated oleic acid and the saturated palmitic acid were virtually ineffective. The combined effects of the PUFAs on INa and ICa may reduce neuronal excitability and may exert anticonvulsive effects in vivo.

Vreugdenhil, M; Bruehl, C; Voskuyl, R A; Kang, J X; Leaf, A; Wadman, W J

1996-01-01

233

Dual inhibition of sodium-mediated proton and calcium efflux triggers non-apoptotic cell death in malignant gliomas  

PubMed Central

Malignant glioma cells maintain an elevated intracellular pH (pHi) within hypoxic-ischemic tumor microenvironments through persistent activation of sodium-proton transport (McLean et al., 2000). Amiloride has been reported to selectively kill human malignant glioma cell lines but not primary astrocytes (Hegde et al., 2004). While amiloride reduces pHi of malignant gliomas by inhibiting isoform 1 of sodium-proton exchange (NHE1), direct acidification was shown to be cytostatic rather than cytotoxic. At cytotoxic concentrations, amiloride has multiple drug targets including inhibition of NHE1 and sodium calcium exchange. Amiloride's glioma cytotoxicity can be explained, at least in part, by dual inhibition of NHE1 and of Na+-dependent calcium efflux by isoform 1.1 of the sodium calcium exchanger (NCX1.1) , which increases [Ca2+]i and initiates glioma cell demise. As a result of persistent NHE1 activity, cytosolic free levels of sodium ([Na+]i) in U87 and C6 glioma cells are elevated 3-fold, as compared with normal astrocytes. Basal cytosolic free calcium levels ([Ca2+]i) also are increased 5-fold. 2?, 4?-dichlorobenzamil (DCB) inhibits the sodium-dependent calcium transporter (NCX1.1) much more potently than NHE1. DCB was employed in a concentration-dependent fashion in glioma cells to selectively inhibit the forward mode of NCX1.1 at ?1uM, while dually inhibiting both NHE1 and NCX1.1 at ?20uM. DCB (1uM) was not cytotoxic to glioma cells, while DCB (20?M) further increased basal elevated levels of [Ca2+]i in glioma cells that was followed by cell demise. Cariporide and SEA0400 are more specific inhibitors of NHE1 and NCX1.1 than amiloride or DCB, respectively. Individually, Cariporide and SEA0400 are not cytotoxic, but in combination induced glioma cell death. Like amiloride, the combination of Cariporide and SEA0400 produced glioma cell death in the absence of demonstrable caspase-activation.

Harley, William; Floyd, Candace; Dunn, Tamara; Zhang, Xiao-Dong; Chen, Tsung-Yu; Hegde, Manu; Palandoken, Hasan; Nantz, Michael H.; Leon, Leonardo; Carraway, K L; Lyeth, Bruce; Gorin, Fredric A.

2010-01-01

234

EFFECTS OF CALCIUM SODIUM ETHYLENEDIAMINETETRA - ACETATE ON THE KINETICS OF DISTRIBUTION AND EXCRETION OF LEAD IN THE RAT  

Microsoft Academic Search

The effects of calcium sodium ethylenediaminetetra-acetate (CaNa2EDTA) on the kinetics of distribution and excretion of lead (210Pb) have been studied in rats. When the chelant was given intravenously, at 50 mg.\\/rat daily after a single intravenous injection of 100 ?g. lead\\/rat, it greatly increased the urinary excretion of lead but reduced the faecal excretion. The greatest effects occurred in the

N. Castellino; S. Aloj

1965-01-01

235

I. Effect of acetylsalicylic acid upon gastric activity and the modifying action of calcium gluconate and sodium bicarbonate  

Microsoft Academic Search

Conclusions1. In some normal human subjects and normal dogs, single oral doses (12 gms.) of acetylsalicylic acid caused gastric retention;\\u000a the addition of calcium gluconate tended to increase the degree of retention while the addition of sodium bicarbonate increased\\u000a the rate of gastric evacuation.\\u000a \\u000a 2. In normal human subjects and normal dogs, single oral doses of acetylsalicylic acid increased the

J. G. Schnedorf; W. B. Bradley; A. C. Ivy

1936-01-01

236

Equilibrium Studies of Sodium-Ammonium, Potassium-Ammonium, and Calcium-Ammonium Exchanges on Clinoptilolite Zeolite  

Microsoft Academic Search

Forward and reverse ion-exchange isotherms for the binary sodium-ammonium, potassium-ammonium, and calcium-ammonium systems on clinoptilolite have been measured in aqueous solutions at a total concentration of 0.1 equiv\\/dm and at 298 K. Prior to exchange experiments it was attempted to prepare homoionic forms of the zeolite by exhaustive treatments with appropriate salt solutions of cations. With no binary exchanges, full

M. A. Jama; H. Yuecel

1989-01-01

237

Evaluation of the Health Aspects of Citric Acid, Sodium Citrate, Potassium Citrate, Calcium Citrate, Ammonium Citrate, Triethyl Citrate, Isopropyl Citrate, and Stearyl Citrate as Food Ingredients.  

National Technical Information Service (NTIS)

The report, by a group of qualified scientists designated the Select Committee on GRAS Substances (SCOGS), provides an independent evaluation of the safety of citric acid, sodium citrate, potassium citrate, calcium citrate, ammonium citrate, triethyl citr...

1977-01-01

238

Molecular cloning of a fourth member of the potassium-dependent sodium-calcium exchanger gene family, NCKX4.  

PubMed

We report here the identification and characterization of a fourth member of the potassium-dependent sodium-calcium exchanger gene family, NCKX4 (gene SLC24A4), which mapped to the chromosomal region 14q32. Human NCKX4 encoded a protein of 605 amino acids that displayed a high level of sequence identity to previously described family members, rod NCKX1 (gene SLC24A1), cone/neuronal NCKX2 (gene SLC24A2), and ubiquitous NCKX3 (gene SLC24A3), in the hydrophobic regions surrounding the alpha-repeat sequences thought to form the ion-binding pocket used for transport. The protein product of the NCKX4 gene shared the highest level of amino acid identity, as well as an almost identical arrangement of exon boundaries, with NCKX3, indicating that these two genes have arisen from a recent duplication event. NCKX4 transcripts were abundantly expressed in all brain regions, aorta, lung, and thymus, as well as at a lower level in many other tissues. The NCKX4 protein demonstrated potassium-dependent sodium calcium exchanger activity when assayed in transfected HEK293 cells using digital imaging of fura-2 fluorescence. The discovery of NCKX4, as far as can be ascertained from the current version of the human genome sequence, completes the mammalian potassium-dependent sodium-calcium exchanger gene family. PMID:12379639

Li, Xiao-Fang; Kraev, Alexander S; Lytton, Jonathan

2002-12-13

239

Effect of biomedical organic compounds on the setting reaction of calcium phosphates.  

PubMed

In the present study, the effect of biomedical organic compounds (starch, sodium alginate, chitosan and gelatin) on the hydration of calcium phosphates was studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and XPS analysis. Amorphous calcium phosphate (ACP) was prepared by a mechanochemical route and mixed with biomedical organic compounds. A solidification reaction occurred between ACP and dicalcium phosphate dihydrate (DCPD); the hydration product was poorly crystallized hydroxyapatite (HA). During the setting reaction of ACP and DCPD, the presence of biomedical organic compounds had an effect on the hydration product: the bonding energies of the primary elements (Ca, P) in the hydration product (HA) were changed; also different hydration morphologies, self-setting properties, rheological properties and mechanical strength of the cement were obtained. This work will allow advances in the synthesis of bionic composite calcium phosphate cement (CPC). PMID:19811895

Yu, Tao; Ye, Jiandong; Gao, Chengying; Yu, Long; Wang, Yingjun

2010-01-01

240

Simultaneous measurements of magnesium, calcium and sodium influxes in perfused squid giant axons under membrane potential control.  

PubMed Central

1. Giant axons from the squids Dosidicus gigas, Loligo forbesi and Loligo vulgaris were internally perfused with 550 or 275 mM KF plus sucrose and bathed in artificial sea water containing 45Ca, 28Mg or mixtures of 45Ca-28Mg or 45Ca-22Na. Resting influxes and extra influxes during voltage-clamp pulses were measured by collecting and counting the internal perfusate. 2. For Dosidicus axons in 10 mM-CaCl2 the resting influx of calcium was 0-016 +/- 0-007 p-mole/cm2 sec and a linear function of external concentration. For two experiments in 10 and 84-7 mM-CaCl2, 100 nM tetrodotoxin had no effect. Resting calcium influx in 10 mM-CaCl2 was 0-017 +/- 0-013 p-mole/cm2 sec for Loligo axons. 3. With 55 mM-MgCl2 outside the average resting magnesium influx was 0-124 +/- 0-080 p-mole/cm2 sec for Loligo axons. Discarding one aberrant point the value is 0-105 +/- 0-046 which is not significantly different from the resting calcium influx for Dosidicus fibres in 55 mM-CaCl2, given as 0-094 p-mole/cm2 sec by the regression line shown in Fig. 1. In two experiments 150 nM tetrodotoxin had no effect. 4. With 430 mM-NaCl outside 100 nM tetrodotoxin reduced the average resting influx of sodium in Dosidicus axon from 27-7 +/- 4-5 to 25-1 +/- 6-2 p-mole/cm2 sec and for Loligo fibres in 460 mM-NaCl from 50-5 +/- 4 to 20 +/- 8 p-mole/cm2 sec. 5. Using depolarizing pulses of various durations, the extra calcium influx occurred in two phases. The early phase was eliminated by external application of tetrodotoxin. The results of analysis are consistent with, but do not rigorously demonstrate, the conclusion that the tetrodotoxin sensitive calcium entry is flowing through the normal sodium channels (cf. Baker, Hodgkin & Ridgway, 1971). 6. Measurements of extra influxes using 22Na and 45Ca simultaneously indicate that the time courses of tetrodotoxin sensitive calcium and sodium entry are similar but not necessarily identical. It is very doubtful that any significant calcium entry occurs before the sodium or is involved in the activation of the sodium system. 7. These measurements confirm for Loligo, as previously shown for Dosidicus axons, that the magnitude and time course of the sodium entry during a depolarizing pulse deduced from electrical measurements is the same as that measured with 22Na. 8. Using 28Mg, or mixtures of 45Ca and 28Mg, we observed a single phase of magnesium entry which was insensitive to external tetrodotoxin or internal tetraethyl ammonium. The magnitude of the magnesium influx was considerably greater than the calcium extra entry and large enough to have been detected in the experiments of Meves & Vogel (1973) if it represented current. 9. We suggest the possibility that the calcium and magnesium extra influxes, after external treatment with tetrodotoxin, during a depolarizing pulse, do not contribute to the measured current.

Rojas, E; Taylor, R E

1975-01-01

241

Simultaneous measurements of magnesium, calcium and sodium influxes in perfused squid giant axons under membrane potential control.  

PubMed

1. Giant axons from the squids Dosidicus gigas, Loligo forbesi and Loligo vulgaris were internally perfused with 550 or 275 mM KF plus sucrose and bathed in artificial sea water containing 45Ca, 28Mg or mixtures of 45Ca-28Mg or 45Ca-22Na. Resting influxes and extra influxes during voltage-clamp pulses were measured by collecting and counting the internal perfusate. 2. For Dosidicus axons in 10 mM-CaCl2 the resting influx of calcium was 0-016 +/- 0-007 p-mole/cm2 sec and a linear function of external concentration. For two experiments in 10 and 84-7 mM-CaCl2, 100 nM tetrodotoxin had no effect. Resting calcium influx in 10 mM-CaCl2 was 0-017 +/- 0-013 p-mole/cm2 sec for Loligo axons. 3. With 55 mM-MgCl2 outside the average resting magnesium influx was 0-124 +/- 0-080 p-mole/cm2 sec for Loligo axons. Discarding one aberrant point the value is 0-105 +/- 0-046 which is not significantly different from the resting calcium influx for Dosidicus fibres in 55 mM-CaCl2, given as 0-094 p-mole/cm2 sec by the regression line shown in Fig. 1. In two experiments 150 nM tetrodotoxin had no effect. 4. With 430 mM-NaCl outside 100 nM tetrodotoxin reduced the average resting influx of sodium in Dosidicus axon from 27-7 +/- 4-5 to 25-1 +/- 6-2 p-mole/cm2 sec and for Loligo fibres in 460 mM-NaCl from 50-5 +/- 4 to 20 +/- 8 p-mole/cm2 sec. 5. Using depolarizing pulses of various durations, the extra calcium influx occurred in two phases. The early phase was eliminated by external application of tetrodotoxin. The results of analysis are consistent with, but do not rigorously demonstrate, the conclusion that the tetrodotoxin sensitive calcium entry is flowing through the normal sodium channels (cf. Baker, Hodgkin & Ridgway, 1971). 6. Measurements of extra influxes using 22Na and 45Ca simultaneously indicate that the time courses of tetrodotoxin sensitive calcium and sodium entry are similar but not necessarily identical. It is very doubtful that any significant calcium entry occurs before the sodium or is involved in the activation of the sodium system. 7. These measurements confirm for Loligo, as previously shown for Dosidicus axons, that the magnitude and time course of the sodium entry during a depolarizing pulse deduced from electrical measurements is the same as that measured with 22Na. 8. Using 28Mg, or mixtures of 45Ca and 28Mg, we observed a single phase of magnesium entry which was insensitive to external tetrodotoxin or internal tetraethyl ammonium. The magnitude of the magnesium influx was considerably greater than the calcium extra entry and large enough to have been detected in the experiments of Meves & Vogel (1973) if it represented current. 9. We suggest the possibility that the calcium and magnesium extra influxes, after external treatment with tetrodotoxin, during a depolarizing pulse, do not contribute to the measured current. PMID:1202193

Rojas, E; Taylor, R E

1975-10-01

242

Variation in crystal structure, ionic conductivity, and magnetic properties with the water uptake of a new hydrated sodium. beta. double prime ferrite  

SciTech Connect

The room temperature single-crystal x-ray data of Na{sub 1.5}(H{sub 3}O){sub 0.5}Fe{sub 10}ZnO{sub 17} + 0.3H{sub 2}O (hydrated sodium {beta}{double prime} alumina-like ferrite) were refined. The space group is R{anti 3}m and the hexagonal cell parameters are a = 5.940, c = 35.731 {angstrom}. Water molecules are localized in the conduction region and the total amount of absorbed water depends on hydration conditions, leading to different possible chemical compositions. By thermogravimetric methods the amount of the absorbed water could be measured. This compound is a poor ionic conductor in comparison with {beta}{minus}{double prime} aluminas. Two distinct types of magnetic behavior were observed for crystals of the same preparation, but in all cases water uptake leads to an enhancement of a ferromagnetic component.

Nicolopoulos, S.; Vincent, H.; Anne, M. (CNRS, Grenoble (France)); Joubert, J.C. (ENSPG, Saint Martin d'Heres (France))

1990-08-01

243

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

Microsoft Academic Search

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

Josephine Lutz

244

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

Microsoft Academic Search

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

Paul McMillan; Bernard Piriou; Alexandra Navrotsky

1982-01-01

245

Dehydration\\/recrystallization mechanisms, energetics, and kinetics of hydrated calcium silicate minerals: an in situ TGA\\/DSC and synchrotron radiation SAXS\\/WAXS study  

Microsoft Academic Search

The dehydration and recrystallization of the natural hydrated calcium silicates xonotlite [Ca6Si6O17(OH)2], 11 anomalous tobermorite [Ca5Si6O16(OH)24H2O], and hillebrandite [Ca2SiO3(OH)2] were studied in situ by dynamic heating (5C min?1) differential scanning calorimetry\\/thermogravimetric analysis (TGA\\/DSC) and synchrotron small- and wide-angle X-ray scattering (SAXS\\/WAXS). All have structures based on silicate chains with a repeat unit of three tetrahedra (dreierketten). Room-T infrared data for

S Shaw; C. M. B Henderson; B. U Komanschek

2000-01-01

246

Surfactant effects on gas hydrate formation  

Microsoft Academic Search

Micellar solutions were found to increase gas hydrate formation rate and alter formation mechanism for ethane and natural gas hydrates. A critical micellar concentration (CMC) of sodium dodecyl sulfate water solution was found to be 242 ppm at hydrate-forming conditions, where CMC was best determined by hydrate induction time. At surfactant concentrations above the CMC, hydrate formation rates in a

Y. Zhong; R. E. Rogers

2000-01-01

247

Selective inhibition of sodium-calcium exchanger by SEA-0400 decreases early and delayed afterdepolarization in canine heart  

PubMed Central

The sodiumcalcium exchanger (NCX) was considered to play an important role in arrhythmogenesis under certain conditions such as heart failure or calcium overload. In the present study, the effect of SEA-0400, a selective inhibitor of the NCX, was investigated on early and delayed afterdepolarizations in canine ventricular papillary muscles and Purkinje fibres by applying conventional microelectrode techniques at 37C. The amplitude of both early and delayed afterdepolarizations was markedly decreased by 1 ?M SEA-0400 from 26.62.5 to 14.81.8 mV (n=9, P<0.05) and from 12.51.7 to 5.91.4 mV (n=3, P<0.05), respectively. In enzymatically isolated canine ventricular myocytes, SEA-0400 did not change significantly the L-type calcium current and the intracellular calcium transient, studied using the whole-cell configuration of the patch-clamp technique and Fura-2 ratiometric fluorometry. It is concluded that, through the reduction of calcium overload, specific inhibition of the NCX current by SEA-0400 may abolish triggered arrhythmias.

Nagy, Zsolt A; Virag, Laszlo; Toth, Andras; Biliczki, Peter; Acsai, Karoly; Banyasz, Tamas; Nanasi, Peter; Papp, Julius Gy; Varro, Andras

2004-01-01

248

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

249

Seeing the Forest through the Trees: towards a Unified View on Physiological Calcium Regulation of Voltage-Gated Sodium Channels  

PubMed Central

Voltage-gated sodium channels (NaVs) underlie the upstroke of the action potential in the excitable tissues of nerve and muscle. After opening, NaVs rapidly undergo inactivation, a crucial process through which sodium conductance is negatively regulated. Disruption of inactivation by inherited mutations is an established cause of lethal cardiac arrhythmia, epilepsy, or painful syndromes. Intracellular calcium ions (Ca2+) modulate sodium channel inactivation, and multiple players have been suggested in this process, including the cytoplasmic NaV C-terminal region including two EF-hands and an IQ motif, the NaV domain III-IV linker, and calmodulin. Calmodulin can bind to the IQ domain in both Ca2+-bound and Ca2+-free conditions, but only to the DIII-IV linker in a Ca2+-loaded state. The mechanism of Ca2+ regulation, and its composite effect(s) on channel gating, has been shrouded in much controversy owing to numerous apparent experimental inconsistencies. Herein, we attempt to summarize these disparate data and propose a novel, to our knowledge, physiological mechanism whereby calcium ions promote sodium current facilitation due to Ca2+ memory at high-action-potential frequencies where Ca2+ levels may accumulate. The available data suggest that this phenomenon may be disrupted in diseases where cytoplasmic calcium ion levels are chronically high and where targeted phosphorylation may decouple the Ca2+ regulatory machinery. Many NaV disease mutations associated with electrical dysfunction are located in the Ca2+-sensing machinery and misregulation of Ca2+-dependent channel modulation is likely to contribute to disease phenotypes.

Van Petegem, Filip; Lobo, Paolo A.; Ahern, Christopher A.

2012-01-01

250

Gd3+ and Calcium Sensitive, Sodium Leak Currents Are Features of Weak Membrane-Glass Seals in Patch Clamp Recordings  

PubMed Central

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 M Gd3+, 100 M 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 M mibefradil or 100 M 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.

Chemin, Jean; Monteil, Arnaud; Spafford, J. David

2014-01-01

251

Diferentes tipos de hidratao durante o exerccio prolongado e sua influncia sobre o sdio plasmtico Different types of hydration during a lenghened exercise and their influence on plasmatic sodium  

Microsoft Academic Search

This study aims at identifying alterations in plasmatic sodium concentration, concerning four hydration procedures: a) water ad libitum; b) scheduled water; c) sport drink of type1 (SD-T1); d) and sport drink of type 2 (SD-T2). An intragroup (intranalysis) and an intergroup (interanalysis) were performed on hydration procedures during a physical work with a duration of 120 minutes and an intensity

Salvador Zamora Navarro

252

Effects of Sodium and Hydrogen Flourides on the Metabolism of Flourine, Calcium, and Phosphorus in Rats  

Microsoft Academic Search

Rats given 4 mg. fluoride\\/kg.\\/day for eight days excreted more calcium and phosphorus and retained less than the controls. In bone ash from rats given different fluoride doses for 40 days the calcium and phosphorus were maximal after a total dose of about 250 ?g. fluoride\\/rat, but fell to subnormal levels after higher doses. The calcium and phosphorus levels in

P. Macuch; J. Kortus; G. Balazova; J. Mayer

1968-01-01

253

Aqueous solubility diagrams for cementitious waste stabilization systems. 4. A carbonation model for Zn-doped calcium silicate hydrate by Gibbs energy minimization.  

PubMed

A thermodynamic Gibbs energy minimization (GEM) solid solution-aqueous solution (SSAS) equilibrium model was used to determine the solubility of Zn from calcium silicate hydrate (CSH) phases doped with 0, 0.1, 1, 5, and 10% Zn at a unity (Ca+Zn)/Si molar ratio. Both the stoichiometry and standard molar Gibbs energy (G(o)298) of the Zn-bearing end-member in the ideal ternary Zn-bearing calcium silicate hydrate (CZSH) solid solution were determined by a "dual-thermodynamic" (GEM-DT) estimation technique. The SSAS model reproduces a complex sequence of reactions suggested to occur in a long-term weathering scenario of cementitious waste forms at subsurface repository conditions. The GEM model of CZSH leaching at several Zn loadings and solid/water (s/w) ratios in a C02-free system showed that, upon complete dissolution of portlandite and calcium zincate phases at decreasing s/w < 0.01 mol x kg(H2O)(-1), the total dissolved concentrations Si(aq), Ca(aq), and Zn(aq) are controlled by a CZSH solid solution of changing composition, with a trough-like Znaq drop by 2-3 orders of magnitude. Carbonation was simulated in another GEM model run series by CO2 titration of the system with initial s/w approximately 0.9 mol/kg(H2O). Formation of (Ca,Zn)-CO3 nonideal solid solution was predicted already at early reaction stage in the presence of both portlandite and calcium zincate hydrate phases. Upon their disappearance, pH, Zn(aq), C(aq), and fCO2 were predicted to change due to the incongruent dissolution of two concurrent CZSH-I and CZSH-II solid solutions, until the total re-partitioning of Ca and Zn into a carbonate solid solution coexisting with amorphous silica at fCO2 > 0.1 bar. Along this solid-phase transition, dissolved Zn(aq) concentrations follow a highly nonlinear trend. The model results predict that at low to moderate Zn loading (< or = 1% per mole Si), CZSH-type compounds can efficiently immobilize Zn in the near field of a cement-stabilized waste repository. PMID:12144269

Kulik, Dmitrii A; Kersten, Michael

2002-07-01

254

Effect of sodium polyacrylate molecular weight on the crystallogenesis of calcium carbonate  

NASA Astrophysics Data System (ADS)

Aqueous solutions of sodium polyacrylates (NaPA) series having molecular weights ( Mw) ranging from 2540 to 9890 g mol -1 are used as precipitation media to control the size and shape of calcium carbonate (CaCO 3) particles. The retarding effect of polyacrylates on CaCO 3 nucleation is evidenced by the increase of the induction time, ?, of the precipitated CaCO 3, from ?=55 s in the absence of additives, to ? values in the range 100-2500 s in the presence of NaPA samples. The data also show the coexistence of two polymorphs, calcite and vaterite, for CaCO 3 particles as prepared in the presence of NaPA samples. The vaterite fraction, fv, varies in all instances with the polymer concentration, Cpoly (g. L -1), and reaches its maximum value, fv,max at optimal ratio, R (mol. g -1), of Ca ion to polymer (NaPA), R=[Ca]/([NaPA]=Cpoly). No simple general trend is found to explain the influence of the molecular weight ( Mw) of NaPA on the induction time, ?, and on the vaterite fraction, fv, since these two parameters are found to vary with Cpoly and Mw. However, under certain experimental conditions, an optimum polymer molecular weight ( Mw=5530 g mol -1) of the NaPA series, gives the highest values of fv,max and ?. Such optimum indicates the influence of Mw of NaPA on CaCO 3 nucleation and growth, and it is related to the surface density and the rate of adsorption of the polymer onto the growing crystal. The CaCO 3 particle size is reduced from about 20 ?m, as obtained in the control experiment, to sizes varying in the range 2-8 ?m in the presence NaPA samples. Polymers having low Mw values ( Mw<5000 g mol -1) are found to be more efficient in reducing the CaCO 3 particle size.

Jada, A.; Ait Akbour, R.; Jacquemet, C.; Suau, J. M.; Guerret, O.

2007-08-01

255

Apatite-forming ability and magnetic properties of glass-ceramics containing zinc ferrite and calcium sodium phosphate phases  

Microsoft Academic Search

Fine particles of zinc ferrite (ZnFe2O4) and calcium sodium phosphate [NaCaPO4] were crystallized in bulk x(ZnO, Fe2O3)(65?x)SiO220(CaO, P2O5)15Na2O (6?x?21mol %) glassy matrix by heat treatment. Initial magnetization curves reveal that samples with x=6 and 9 mol % zinciron oxide exhibit both ferrimagnetic and paramagnetic contributions, whereas, samples with x>9mol % zinciron oxide exhibit only ferrimagnetic contribution. This observation is supported

Rajendra Kumar Singh; A. Srinivasan

2010-01-01

256

Potential and tension changes induced by sodium removal in dog Purkinje fibres: role of an electrogenic sodium-calcium exchange.  

PubMed

1. Isolated dog Purkinje fibres were bathed in K-free media or in the presence of ouabain 10(-4) M in order to depress the electrogenic sodium pump activity. Membrane potential and mechanical tension were recorded in the presence of normal external sodium concentration and during lowering or removal of external Na. 2. Lowering or removal of external Na (Na being replaced by choline, Tris, sucrose or Li) induced a hyperpolarization and a contracture which reached a maximum after 1 or 2 min and then decreased progressively. Using Tris, Em increased from -40 +/- 3 to -72 +/- 10 mV (n = 39). The Na-free contracture and hyperpolarization did not occur in the absence of Na pump depression. 3. Tetrodotoxin (1.2 x 10(-5)M), Mn (4 mM), verapamil (1-4 x 10(-5) M) tetraethylammonium (5 mM), 4-aminopyridine (5 mM) and Cs (20 mM, in the presence of ouabain) did not alter the Na-free contracture and hyperpolarization. On the other hand Mn (20 mM), acid media (external pH less than 6.0) and low temperatures depressed or suppressed both the hyperpolarization and contracture. Lanthanum (0.4 mM) did not suppress the hyperpolarization and the contracture. On the contrary the Na-free contracture was generally increased in the presence of La. 4. Caffeine (10 mM) induced strong contractures with no changes in Em, thus demonstrating the possibility for the Purkinje fibers of developing contractures without concomitant hyperpolarizations. 5. It can be concluded that the Na-free contracture and hyperpolarization are not due to changes in passive conductances but are related to the functioning of an electrogenic Na-Ca exchange mechanism which carries inwardly 1 Ca and outwardly 3 or more Na. PMID:7264984

Croaboeuf, E; Gautier, P; Giuraudou, P

1981-02-01

257

Molecular dynamics modeling of the interface between surface functionalized graphitic structures and calcium-silicate-hydrate: interaction energies, structure, and dynamics.  

PubMed

Molecular dynamics simulations were performed to study the molecular-scale energetic, structural, and dynamic properties of the interface between surface functionalized graphitic structures and calcium-silicate-hydrate (C-S-H). The 9 A tobermorite structure was used as a model for C-S-H, the main building block ("the glue") that hold a cementitious matrix together. Six types of carbon surface structures were investigated: a pristine graphite plane and five graphite planes functionalized with hydroxyl (OH), carboxyl (COOH), carboxylate (COO(-), deprotonated carboxyl), carbonyl (CO), and amine (NH(2)) groups. Results demonstrated the dominant role of electrostatic forces in the interfacial interactions and indicated that the polarity of the functional group can be used as an indicator of affinity to C-S-H. MD simulations revealed that an optimal number of polar oxygen containing groups may exist for efficient graphitic structure/cement interaction and emphasized the mediating role of Ca(2+) counterions in the interfacial interactions. PMID:18486142

Sanchez, F; Zhang, L

2008-07-15

258

The Plasma Membrane Ca2+ ATPase and the Plasma Membrane Sodium Calcium Exchanger Cooperate in the Regulation of Cell Calcium  

PubMed Central

Calcium is an ambivalent signal: it is essential for the correct functioning of cell life, but may also become dangerous to it. The plasma membrane Ca2+ ATPase (PMCA) and the plasma membrane Na+/Ca2+ exchanger (NCX) are the two mechanisms responsible for Ca2+ extrusion. The NCX has low Ca2+ affinity but high capacity for Ca2+ transport, whereas the PMCA has a high Ca2+ affinity but low transport capacity for it. Thus, traditionally, the PMCA pump has been attributed a housekeeping role in maintaining cytosolic Ca2+, and the NCX the dynamic role of counteracting large cytosolic Ca2+ variations (especially in excitable cells). This view of the roles of the two Ca2+ extrusion systems has been recently revised, as the specific functional properties of the numerous PMCA isoforms and splicing variants suggests that they may have evolved to cover both the basal Ca2+ regulation (in the 100 nM range) and the Ca2+ transients generated by cell stimulation (in the ?M range).

Brini, Marisa; Carafoli, Ernesto

2011-01-01

259

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

SciTech Connect

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.

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

260

Occurrence of methane hydrate in saturated and unsaturated solutions of sodium chloride and water in dependence of temperature and pressure  

Microsoft Academic Search

Experimental results of the formation of methane hydrate in dependence of temperature and pressure in unsaturated solutions of NaCl in water will be presented in a temperature range from 261.85 to 285.98 K and pressure up to 11.0 MPa. Furthermore the four-phase equilibrium NaCl X 2HO \\/SUB s\\/ -CH X nHO \\/SUB s\\/ -L-G has been calculated from the experimental

J. L. de Roo; G. A. M. Diepen; R. N. Lichtenthaler; C. J. Peters

1983-01-01

261

Sodium-calcium exchanger complexed with GM1 ganglioside in nuclear membrane transfers calcium from nucleoplasm to endoplasmic reticulum  

PubMed Central

The inner membrane of the nuclear envelope (NE) was previously shown to contain a Na/Ca exchanger (NCX) tightly linked to GM1 ganglioside that mediates transfer of nucleoplasmic Ca2+ to the NE lumen and constitutes a cytoprotective mechanism. This transfer was initially observed with isolated nuclei and is now demonstrated in living cells in relation to subcellular Ca2+ dynamics. Four cell lines with varying expression of NCX and GM1 in the NE were transfected with cameleon-fluorescent Ca2+ indicators genetically targeted to NE/endoplasmic reticulum (ER) and nucleoplasm to monitor [Ca2+]ne/er and [Ca2+]n respectively. Cytosolic Ca2+ ([Ca2+]cyt) was indicated with fura-2. Thapsigargin caused progressive loss of [Ca2+]ne/er, which was rapidly replaced on addition of extrinsic Ca2+ to those cells containing fully functional NCX/GM1: differentiated NG10815 and C6 cells. Reduced elevation of [Ca2+]ne/er following thapsigargin depletion occurred in cells containing little or no GM1 in the NE: undifferentiated NG10815 and NG-CR72 cells. No change in [Ca2+]ne/er due to applied Ca2+ was seen in Jurkat cells, which entirely lack NCX. Ca2+ entry to NE/ER was also blocked by KB-R7943, inhibitor of NCX. [Ca2+]n and [Ca2+]cyt were elevated independent of [Ca2+]ne/er and remained in approximate equilibrium with each other. Ca2+ rise in the ER originated in the NE region and extended to the entire ER network. These results indicate the nuclear NCX/GM1 complex acts to gate Ca2+ transfer from cytosol to ER, an alternate route to the sarcoplasmic/endoplasmic reticulum calcium ATPase pump. They also suggest a possible contributory mechanism for independent regulation of nuclear Ca2+.

Wu, Gusheng; Xie, Xin; Lu, Zi-Hua; Ledeen, Robert W.

2009-01-01

262

Intraoral evaluation of mineralization of cosmetic defects by a toothpaste containing calcium, fluoride, and sodium bicarbonate.  

PubMed

New dual-phase fluoride toothpastes that contain soluble calcium, phosphate, and baking soda have recently been introduced into the market. These toothpastes are designed to fill in small surface defects in tooth enamel and thereby enhance tooth esthetics such as gloss. This two-part study was designed to assess these superficial mineralizing effects from using one of these products compared with an experimental calcium-containing, bicarbonate-free formulation and a conventional fluoride toothpaste using an intraoral model. Enamel specimens with 4 types of defects were mounted into an intraoral appliance and placed in the mouths of volunteers for 1 month. The four types of defects were whitening toothpaste abrasion, coarse abrasion, natural dimpling, and acid etching. Before and after intraoral exposure, scanning electron microscope photographs of the specimens were made. The surface microhardness of the acid-etched specimens also was determined. The volunteers brushed their specimens twice daily with one of three randomly assigned toothpastes. The toothpastes were a two-phase, calcium-containing, bicarbonate-based toothpaste; an experimental, two-phase, calcium-containing, bicarbonate-free toothpaste; and a conventional toothpaste. Only the calcium-containing toothpastes showed unequivocal signs of mineral deposition into surface defects, leading to smoothing of the enamel. All three products significantly increased the hardness of the etched enamel, presumably because of fluoride. However, only the two calcium-containing toothpastes gave significantly greater hardness increases than the conventional toothpaste; the specimens treated with a conventional toothpaste were indistinguishable from those treated with saliva. PMID:15645904

Litkowski, Leonard J; Quinlan, Kathleen B; Ross, David R; Ghassemi, Annahita; Winston, Anthony; Charig, Andrew; Flickinger, Mark; Vorwerk, Linda

2004-09-01

263

Calcium stone disease: a multiform reality  

Microsoft Academic Search

In calcium renal stones, calcium oxalate and calcium phosphate in various crystal forms and states of hydration can be identified. Calcium oxalate monohydrate (COM) or whewellite and calcium oxalate dihydrate (COD) or weddellite are the commonest constituents of calcium stones. Calcium oxalate stones may be pure or mixed, usually with calcium phosphate or sometimes with uric acid or ammonium urate.

Alberto Trinchieri; Chiara Castelnuovo; Renata Lizzano; Giampaolo Zanetti

2005-01-01

264

Effect of different calcium aluminate hydrates on ettringite formation and expansion of high alumina cement-based expansive cement pastes  

Microsoft Academic Search

Different hydrated high alumina cement (H-HAC) mixtures containing mainly CAH10, C2AH8 or C3AH6 obtained at different temperatures were studied with respect to their performance as the Al-bearing component in HAC-based expansive additives. Free expansion and ettringite formation potentials of expansive cement using the different H-HAC preparations were reported. It was shown that H-HAC containing predominantly CAH10 and C2AH8 reacted more

Yan Fu; Jian Ding; J. J. Beaudoin

1996-01-01

265

Antiplatelet and calcium inhibitory properties of eugenol and sodium eugenol acetate.  

PubMed

1. Eugenol (3-methoxy-4-hydroxy-propenylbenzene) or sodium eugenol acetate (4-O-acetic acid sodium-3-methoxy-1-propenylbenzene) (0.25, 0.5, 1 mM) concentration-dependently inhibited arachidonic acid (AA)-, collagen-, epinephrine- and ADP-induced platelet aggregation. 2. Eugenol or sodium eugenol acetate inhibited collagen-induced aggregation of washed rabbit platelets synergistically with creatine phosphate/creatine phosphokinase (CP/CPK, 5 mM/10 U/ml) or p-bromophenacyl bromide (p-BPB, 10 microM), and they also potentiated the inhibitory action of imidazole (0.5 mM) on AA-induced aggregation. 3. Eugenol or sodium eugenol acetate (0.25, 0.5, 1 mM) concentration-dependently inhibited AA-induced thromboxane B2 and prostaglandin E2 formation. 4. The rise of intracellular Ca2+ caused by collagen, epinephrine, ADP, and AA were inhibited by eugenol or sodium eugenol acetate (1 mM). PMID:8853295

Chen, S J; Wang, M H; Chen, I J

1996-06-01

266

Determination of sodium, potassium, calcium and magnesium content in milk products by flame atomic absorption spectrometry (FAAS): A joint ISO\\/IDF collaborative study  

Microsoft Academic Search

A flame atomic absorption spectrometry method to determine sodium, potassium, calcium and magnesium content in milk products using dry ashing or wet digestion was evaluated in an international collaborative trial. The study involved 18 participants from six countries. The method was tested on a total of eight milk products: whey protein concentrate, whole milk powder, two processed cheeses, whey powder,

Laurent Nol; Michael Carl; Christelle Vastel; Thierry Gurin

2008-01-01

267

Interactions between mica surfaces in sodium polyacrylate solutions containing calcium ions  

Microsoft Academic Search

Polyacrylic acid (PAA) and its salts find use in a number of different applications, such as in fluids for secondary oil recovery, as dispersing agents for mineral suspensions in, for example, ceramic and paper coating applications, and as flocculants for waste-water treatment. The forces acting between negatively charged muscovite mica surfaces immersed in solutions containing sodium polyacrylate (NaPAA) have been

J. M. Berg; P. M. Claesson; R. D. Neuman

1993-01-01

268

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

Microsoft Academic Search

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

S. E. Doty; R. C. Seagrave

1999-01-01

269

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

Microsoft Academic Search

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

S. E Doty; R. C Seagrave

2000-01-01

270

The epithelial sodium/proton exchanger, NHE3, is necessary for renal and intestinal calcium (re)absorption  

PubMed Central

Passive paracellular proximal tubular (PT) and intestinal calcium (Ca2+) fluxes have been linked to active sodium (re)absorption. Although the epithelial sodium/proton exchanger, NHE3, mediates apical sodium entry at both these sites, its role in Ca2+ homeostasis remains unclear. We, therefore, set out to determine whether NHE3 is necessary for Ca2+ (re)absorption from these epithelia by comparing Ca2+ handling between wild-type and NHE3?/? mice. Serum Ca2+ and plasma parathyroid hormone levels were not different between groups. However, NHE3?/? mice had increased serum 1,25-dihydroxyvitamin D3. The fractional excretion of Ca2+ was also elevated in NHE3?/? mice. Paracellular Ca2+ flux across confluent monolayers of a PT cell culture model was increased by an osmotic gradient equivalent to that generated by NHE3 across the PT in vivo and by overexpression of NHE3. 45Ca2+ uptake after oral gavage and flux studies in Ussing chambers across duodenum of wild-type and NHE3?/? mice confirmed decreased Ca2+ absorption in NHE3?/? mice compared with wild-type mice. Consistent with this, intestinal calbindin-D9K, claudin-2, and claudin-15 mRNA expression was decreased. Microcomputed tomography analysis revealed a perturbation in bone mineralization. NHE3?/? mice had both decreased cortical bone mineral density and trabecular bone mass. Our results demonstrate significant alterations of Ca2+ homeostasis in NHE3?/? mice and provide a molecular link between Na+ and Ca2+ (re)absorption.

Pan, Wanling; Borovac, Jelena; Spicer, Zachary; Hoenderop, Joost G.; Bindels, Rene J.; Shull, Gary E.; Doschak, Michael R.; Cordat, Emmanuelle

2012-01-01

271

Rheology investigations on the influence of addition sodium polyacrylate to calcium carbonate suspensions  

Microsoft Academic Search

The stability of concentrated CaCO3 suspensions (40wt%) on addition of sodium polyacrylate (NaPAA, PA20, with molar mass of 2100) has been investigated using rheological measurements. On addition of NaPAA to the suspension, there is a selective adsorption of PA fraction with molar mass of 20005000. This selective adsorption is due to entropic effects and heterogeneous charge distribution. The smaller sized

Deng Deng; Volodymyr Boyko; Sabrina Montero Pancera; Nikolaus Nestle; Tharwat Tadros

272

Transuranium removal from Hanford high level waste simulants using sodium permanganate and calcium  

Microsoft Academic Search

Plutonium and americium are present in the Hanford high level liquid waste complexant concentrate (CC) due to the presence of complexing agents including di-(2-ethylhexyl) phosphoric acid (D2EHPA), tributylphosphate (TBP), hydroxyethylene diamine triacetic acid (HEDTA), ethylene diamine tetraacetic acid (EDTA), citric acid, glycolic acid, and sodium gluconate. The transuranic concentrations approach 600 nCi\\/g and require processing prior to encapsulation into low

W. R. Wilmarth; S. W. Rosencrance; C. A. Nash; F. F. Fonduer; D. P. Diprete; C. C. Diprete

2000-01-01

273

Oral sustained delivery of diclofenac sodium using calcium chondroitin sulfate matrix.  

PubMed

Chondroitin sulfate (CS) is a potential candidate for colon-specific drug carriers. However, the readily water-soluble nature limits its application as a solid-state drug-delivery vehicle. In this study, the CS formation of a polyelectrolyte complex (PEC) with Ca2+ (CS-Ca) was adapted to retain CS in a solid form for use in a drug-delivery system. Pre-treated CS with poly(ethylene glycol) diglycidyl ether (EX-810) followed by complexation with Ca2+ was also tested (CS-Ca-EX). Diclofenac sodium was used as a drug probe to evaluate the performance of the drug-release behavior of the complexes. The amount of diclofenac sodium released was higher in simulated intestinal fluid (SIF) than in simulated gastric fluid (SGF) due to the anionic groups on CS or the higher solubility of drug itself in PBS. The release profile of diclofenac sodium from CS-Ca-EX was most notably sustained when compared to other groups. Enzymatic degradation by chondroitinase ABC of CS, CS-Ca and CS-Ca-EX exhibited a similar degradation mechanism and GPC revealed the dissolution rate of CS from the three matrix types was, in decreasing order: CS, CS-Ca, CS-Ca-EX. The synergy of the anti-inflammatory activity of diclofenac sodium in CS-based complexes was evaluated using the carrageenan-induced edema rat test. The percentage of swelling was lower for all experimental groups as compared to the control, untreated group. The anti-inflammatory activity of diclofenac in the CS matrix gradually increased up to 9 h but CS-Ca or CS-Ca-EX matrices showed less potency than the CS matrix in reducing inflammation. PMID:16268256

Tsai, Ming-Fung; Chiang, Ya-Ling; Wang, Li-Fang; Huang, Gao-Wei; Wu, Pao-Chu

2005-01-01

274

Use of aqueous solutions of sodium alginate and calcium acetate as quenching liquids  

Microsoft Academic Search

Aqueous solutions of SA are prepared from a film of it obtained from an algal extract. The algai extract is prepared from seaweed of the species Lc~inaria saccharina and digitata. For the quenching solution 1--3% of the dried seaweeds is infused for 3--5 days in a 1% aqueous sodium carbonate solution. To obtain the SA film sulfuric or hydrochloric acid

M. G. Kurmashov

1982-01-01

275

Occurrence of methane hydrate in saturated and unsaturated solutions of sodium chloride and water in dependence of temperature and pressure  

SciTech Connect

Experimental results of the formation of methane hydrate in dependence of temperature and pressure in unsaturated solutions of NaCl in water will be presented in a temperature range from 261.85 to 285.98 K and pressure up to 11.0 MPa. Furthermore the four-phase equilibrium NaCl X 2H/sub 2/O /SUB s/ -CH/sub 4/ X nH/sub 2/O /SUB s/ -L-G has been calculated from the experimental results. Also the heats of transformation of several other equilibria in the ternary system CH/sub 4/-H/sub 2/O-NaCl are obtained.

de Roo, J.L.; Diepen, G.A.M.; Lichtenthaler, R.N.; Peters, C.J.

1983-07-01

276

Sodium pump activity and calcium relaxation in vascular smooth muscle of deoxycorticosterone acetate-salt rats  

SciTech Connect

The Na/sup +/-K/sup +/ pump activity was determined in femoral arterial smooth muscle from deoxycorticosterone acetate (DOCA)-salt hypertensive rats using potassium relaxation and ouabain-sensitive /sup 86/Rb uptake as indices. The membrane-stabilizing effect of calcium and its relation to Na/sup +/-K/sup +/ pump activity also were examined. Femoral arteries from DOCA-salt rats exhibited a greater relaxation in response to potassium addition after contraction with norepinephrine in a low potassium (0.6 mM) Krebs solution. The concentration of potassium required to produce a 50% relaxation was significantly less in DOCA-salt rats. Ouabain-sensitive /sup 86/Rb uptake was significantly greater at 3, 10, and 20 minutes of /sup 86/Rb incubation in femoral arteries from DOCA-salt rats. Linear regression analysis revealed a significant correlation between the uptake of /sup 86/Rb and time of incubation in both control and DOCA-salt rats. A significant difference in the slopes of the regression lines showed that the rate of uptake was greater in DOCA-salt rats. No difference was observed in ouabain-insensitive /sup 86/Rb uptake. A dose-dependent relaxation in response to increasing concentrations of calcium following contraction to norepinephrine was observed in femoral arteries from control and DOCA-salt rats. The relaxation was directly dependent on the level of extracellular potassium and was blocked by ouabain. Femoral arteries from DOCA-salt rats relaxed to a significantly greater extent in response to calcium at each level of potassium when compared with controls. These results provide further evidence for an increase in Na/sup +/-K/sup +/ pump activity in vascular smooth muscle from DOCA-salt hypertensive rats.

Soltis, E.E.; Field, F.P.

1986-11-01

277

High-Power Arctic Lidar for observations of Sodium layer and Calcium Ion Cyclotron Resonance Heating  

NASA Astrophysics Data System (ADS)

The UCLA HIPAS Observatory is located at 64o 54' 22"N, 146o 50' 33" W. It passes under the auroral oval, has a 2.7 m diameter liquid mirror collector (LMT), and two bistatic laser illuminators; a Doubled YAG pumped dye laser and a Doubled (tunable) Alexandrite laser. The first emits 0.1 J - 10 ns pulses at 590nm (Na) at 20 Hz. The second laser emits 0.15 J -10 ns pulses at 393 nm (Ca+) and 391.4 nm (N2) at 10 Hz. New sporadic sodium layers have been observed during the passage of the electrojet and auroras in periods of 20-30 seconds, indicating that sodium is liberated from micrometeors during auroral precipitations. The Laser Induced Fluorescence techniques will be used to observe the acceleration of the Ca+ ions when they are driven by the 80 MW (ERP) 2.85MHz RF array, modulated at the Ca+ ion Cyclotron Frequency. 1. Ionospheric Modifaction and Enviromental Research in the Auroral Region in Plasma Science and the Environment. Publisher: AIP Press, Woodbury, NY. Editors: W. Manheimer, L. Sugiyama, T. Stix; Chapter 3, pgs. 41-75, 1997. Research supported by ONR N00014-96-C-0040

Wuerker, R. F.; Foley, J.; Kidd, P.; Wong, A. Y.

1998-11-01

278

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

PubMed

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

Guan, Wenqiang; Fan, Xuetong

2010-03-01

279

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)

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) 1226H 2O as the starting material; on heating, this decomposes at about 115 C to form monosulfate-14 and bassanite CaSO 40.5H 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.

Meller, Nicola; Kyritsis, Konstantinos; Hall, Christopher

2009-10-01

280

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

USGS Publications Warehouse

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 21-24C). 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).

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

1980-01-01

281

Complete Atrial-Specific Knockout of Sodium-Calcium Exchange Eliminates Sinoatrial Node Pacemaker Activity  

PubMed Central

The origin of sinoatrial node (SAN) pacemaker activity in the heart is controversial. The leading candidates are diastolic depolarization by funny current (If) through HCN4 channels (the Membrane Clock hypothesis), depolarization by cardiac Na-Ca exchange (NCX1) in response to intracellular Ca cycling (the "Calcium Clock" hypothesis), and a combination of the two (Coupled Clock). To address this controversy, we used Cre/loxP technology to generate atrial-specific NCX1 KO mice. NCX1 protein was undetectable in KO atrial tissue, including the SAN. Surface ECG and intracardiac electrograms showed no atrial depolarization and a slow junctional escape rhythm in KO that responded appropriately to ?-adrenergic and muscarinic stimulation. Although KO atria were quiescent they could be stimulated by external pacing suggesting that electrical coupling between cells remained intact. Despite normal electrophysiological properties of If in isolated patch clamped KO SAN cells, pacemaker activity was absent. Recurring Ca sparks were present in all KO SAN cells, suggesting that Ca cycling persists but is uncoupled from the sarcolemma. We conclude that NCX1 is required for normal pacemaker activity in murine SAN.

Groenke, Sabine; Larson, Eric D.; Alber, Sarah; Zhang, Rui; Lamp, Scott T.; Ren, Xiaoyan; Nakano, Haruko; Jordan, Maria C.; Karagueuzian, Hrayr S.; Roos, Kenneth P.; Nakano, Atsushi; Proenza, Catherine; Philipson, Kenneth D.; Goldhaber, Joshua I.

2013-01-01

282

Calcium-dependent regulation of the voltage-gated sodium channel hH1: Intrinsic and extrinsic sensors use a common molecular switch  

PubMed Central

The function of the human cardiac voltage-gated sodium channel NaV1.5 (hH1) is regulated in part by binding of calcium to an EF hand in the C-terminal cytoplasmic domain. hH1 is also regulated via an extrinsic calcium-sensing pathway mediated by calmodulin (CaM) via binding to an IQ motif immediately adjacent to the EF-hand domain. The intrinsic EF-hand domain is shown here to interact with the IQ motif, which controls calcium affinity. Remarkably, mutation of the IQ residues has only a minor effect on CaM affinity but drastically reduces calcium affinity of the EF-hand domain, whereas the Brugada mutation A1924T significantly reduces CaM affinity but has no effect on calcium affinity of the EF-hand domain. Moreover, the differences in the biochemical effects of the mutations directly correlate with contrasting effects on channel electrophysiology. A comprehensive model is proposed in which the hH1 IQ motif serves as a molecular switch, coupling the intrinsic and extrinsic calcium sensors.

Shah, Vikas N.; Wingo, Tammy L.; Weiss, Kevin L.; Williams, Christina K.; Balser, Jeffrey R.; Chazin, Walter J.

2006-01-01

283

EFFECTS OF CALCIUM SODIUM ETHYLENEDIAMINETETRA - ACETATE ON THE KINETICS OF DISTRIBUTION AND EXCRETION OF LEAD IN THE RAT  

PubMed Central

The effects of calcium sodium ethylenediaminetetra-acetate (CaNa2EDTA) on the kinetics of distribution and excretion of lead (210Pb) have been studied in rats. When the chelant was given intravenously, at 50 mg./rat daily after a single intravenous injection of 100 ?g. lead/rat, it greatly increased the urinary excretion of lead but reduced the faecal excretion. The greatest effects occurred in the rats treated with chelant shortly after the lead injection. When the chelant was given seven or more days after the lead the increase in lead excretion was negligible. CaNa2EDTA mobilized lead from every tissue, but the kinetic analysis of the disappearance of 210Pb showed the presence of two elimination phases. Lead ions weakly bound to the cells were rapidly removed by EDTA, whereas the lead fixed to endocellular constituents was only slowly removed. The chelant did not mobilize lead from bone. Probably CaNa2EDTA entered the extravascular space but not the cells. Hence it only accelerated the passage of lead from the cells by lowering the concentration of lead outside them. 210Pb was also given orally in doses of 500 ?g. lead/rat. About 18% of the dose was absorbed through the intestine to be distributed in all tissues. Rats treated orally with CaNa2EDTA showed an increase in urinary lead excretion and a reduction in lead fixed in the body.

Castellino, N.; Aloj, S.

1965-01-01

284

Blockade of the sodium calcium exchanger exhibits anticonvulsant activity in a pilocarpine model of acute seizures in rats  

PubMed Central

Recent evidence suggests that the sodium calcium exchanger (NCX) may contribute to the etiology of pentylenetetrazol-induced seizures. Here we further investigated the role of NCX in the etiology of seizures by quantifying the effects of KB-R7943 and SN-6, potent inhibitors of the reverse mode of NCX subtypes 3 (NCX3) and 1 (NCX1), respectively, on the occurrence of acute seizures and status epilepticus induced by intraperitoneal administration of pilocarpine, a muscarinic acetylcholine receptor agonist. Pretreatment with KB-R7943 significantly reduced the incidence of pilocarpine-induced seizures and status epilepticus in 2256% of treated animals. In the remaining animals that exhibited seizures, KB-R7943 pretreatment delayed the onset of seizures and status epilepticus, and reduced seizure severity. Delayed onset of seizures and reduced seizure severity also were seen following pretreatment with SN-6. These findings suggest that altered NCX activity may contribute to the pathophysiology of pilocarpine-induced seizures and status epilepticus.

Martinez, Yuris; N'Gouemo, Prosper

2010-01-01

285

Structure and properties of the sodium, potassium and calcium salts of 2-(2,3-dimethylphenyl)aminobenzoic acid  

NASA Astrophysics Data System (ADS)

The mefenamic acid sodium, potassium, and calcium salts with general formulae [Na(mef)(H 2O) 2] n nH 2O, [K(mef)(H 2O)] n and [Ca(mef) 2(H 2O) 2] n nH 2O have been synthesised, studied by X-ray crystallography, 1H and 13C NMR and IR spectroscopy. The complex salts are air stable and soluble in water. During heating the Na and K complexes melt in the complexed water and next recrystallise in anhydrous form. In the solid state all salts create one-dimensional coordination polymers. The central atoms are five, six and seven coordinated, respectively, for Na, K and Ca complexes. In all structures exist O sbnd H⋯O, N sbnd H⋯O and C sbnd H⋯O hydrogen bonds. The vibrational analysis has been carried out for mefenamic acid and its three coordination polymer compounds on the basis of experimental results as well as quantum mechanical calculations. The theoretical and experimental vibrational frequencies are similar and reveal characteristic vibrations for all IR active oscillators. In the IR spectra of salts exist strong bands at ca. 1365 and 1600 cm -1 typical for carboxylate groups.

Kruszynski, Rafal; Trzesowska-Kruszynska, Agata; Majewski, Piotr; ?ukaszewicz, Ewa; Majewska, Kamila; Siera?ski, Tomasz; Lewi?ski, Bart?omiej

2010-04-01

286

Analytical model of Sodium, Calcium and Hydrogen exospheres of CoRoT7b -like planets  

NASA Astrophysics Data System (ADS)

A parametric model of the elongated exospheres of CoRoT-7b -like planets is presented here. A numerical, Monte-Carlo model is used to determine the trajectories of ejected particles, calculated by using the full equation of motion. These are accumulated into a matrix to obtain the spatial distributions of exospheric particles. Then, an analytical model is obtained by fitting the numerical data with parametric functions. We focus on the Hydrogen, Sodium and Calcium exospheres that, due to the radiation pressure acceleration, extend in the anti-stellar direction and form a tail. We investigate the role of some physical parameters, like the planetary mass, radius, temperature and distance from the host star. Hence, we run several numerical simulations with different values of the planet-associated physical quantities, studying the effect on the morphology of the exosphere for the various analytical-model parameters. In this way, we can investigate the role of each physical source quantity separately. Since elongated exosphere may be detected in a occultation experiment, the results of such a study may be useful for a quick evaluation of the feasibility of such an observation.

Mura, Alessandro; Lammer, Helmut; Wurz, Peter; Schneider, Jean; Orsini, Stefano; Milillo, Anna; Griessmeier, Jean-Mathias; Odert, Petra; Leitzinger, Martin

2010-05-01

287

Photoresponsive Ion Extraction/Release Systems: Dynamic Ion Optodes for Calcium and Sodium Based on Photochromic Spiropyran  

PubMed Central

Photoresponsive ion extraction/release systems (PRIONERS) represent a highly interesting tool for the localized and time-controlled chemical perturbation of biological materials. We report here on our first results on phototriggered calcium and sodium exchanging materials. Such materials exist in two distinct states (on and off), depending on the wavelength of illumination. We used a combination of spectroscopic and electrochemical methods to obtain a better understanding of the dynamic processes involved in the triggered ion-exchange reaction upon activation of the photoactive compound. The driving force for the ion exchange is the light-induced acidity change of the chromoionophore. Activation with UV light generates a species in the membrane with an increased pKa. Protons are pulled into the membrane, and at the same time, ions are expelled. The selectivity of the system is determined by the employed ionophore. In contrast to photoresponsive ionophore-based systems, the concept presented here is applicable for virtually any ion of interest for which an ionophore exists.

2013-01-01

288

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

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

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

1964-01-01

289

Molecular Dynamics Simulation of the Structure of Calcium Silicate Hydrates. I. Ca 4+ xSi 6O 14+2 x(OH) 4-2 x(H 2O) 2(0 ? x? 1)  

NASA Astrophysics Data System (ADS)

Molecular dynamics has been used to simulate the structure of calcium silicate hydrates (CSH) having Ca/Si ratios of 0.66 and 0.83. In the absence of labile calcium, silicon nuclear magnetic resonance (NMR) shows that the tetrahedral chains move closer together than predicted by the tobermorite model initially adopted. This proximity may lead to bridging between the chains. In the presence of labile calcium, there is a partial rupture of the chains, as seen with NMR. The instability of the bridging tetrahedra in the initial structure causes this rupture. The dissociation of a water molecule releases the oxygen necessary for the reaction. The rupture of the chains creates two new types of tetrahedra in the structure (Q1(2H) and Q1(1H)).

Faucon, P.; Delaye, J. M.; Virlet, J.

1996-11-01

290

Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, C{sub 4}A{sub 3}S{sup }) in the presence of gypsum and varying amounts of calcium hydroxide  

SciTech Connect

Suspensions of synthetic ye'elimite (C{sub 4}A{sub 3}S{sup }) in a saturated gypsum (CS{sup }H{sub 2}) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C{sub 4}A{sub 3}S{sup }, 15% CS{sup }H{sub 2}, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO{sub 4}{sup 2?}/OH{sup ?}) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate.

Hargis, Craig W. [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States)] [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States); Kirchheim, Ana Paula [Department of Civil Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS (Brazil)] [Department of Civil Engineering, Federal University of Rio Grande do Sul, Porto Alegre, RS (Brazil); Monteiro, Paulo J.M., E-mail: monteiro@ce.berkeley.edu [Department of Civil and Environmental Engineering, University of California, Berkeley, CA (United States); Gartner, Ellis M. [Lafarge Centre de Recherche, St. Quentin Fallavier, Isere (France)] [Lafarge Centre de Recherche, St. Quentin Fallavier, Isere (France)

2013-06-15

291

Insight into elastic behavior of calcium silicate hydrated oxide (C-S-H) under pressure and composition effect  

SciTech Connect

The present work relates to the study of structural and elastic properties of Tobermorite 11 A as a function of external pressure and composition in terms of calcium to silicon ratio. Basing on the lattice dynamics method, the main aim of this work is precisely to shed light, for the first time, on the high pressure structural phase transition in Tobermorite 11 A and the possible correlation with some elastic quantities. In order to check the transferability of the potentials used we have, additionally, performed a single calculation based on the density functional theory (DFT) for a pressure of 15 GPa in the case of Ca/Si = 1. The variation of the unit cell parameters with pressure indicates that Tobermorite 11 A undergoes a structural instability around 15 GPa along b-axis and around 20 GPa along a-axis which is confirmed from our calculations of X-Rays diffraction patterns at various pressure values. We have also observed the anisotropic character of the Tobermorite structure for both cases (Ca/Si = 1 and Ca/Si = 0.83). Our results show that around 20 GPa an important change appears in the elastic behaviour of Tobermorite. As pressure increases the calculated elastic quantities for Ca/Si = 1 became closer to those evaluated for Ca/Si = 0.83, which may stimulate further experimental and theoretical research on the matter.

Zaoui, Ali, E-mail: azaoui@polytech-lille.fr

2012-02-15

292

THE BEHAVIOR OF ISOLATED HEARTS OF THE GRASSHOPPER, CHORTOPHAGA VIRIDIFASCIATA, AND THE MOTH, SAMIA WALKERI, IN SOLUTIONS WITH DIFFERENT CONCENTRATIONS OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM  

PubMed Central

1. The blood of Chortophaga viridifasciata was analyzed. The average concentrations of inorganic cations expressed as milligrams per cent are: sodium, 250.66; potassium, 13.52; calcium, 11.40; and magnesium, 51.15. The osmotic pressure of the blood at 0C. is 10.7 atmospheres. Protein and non-protein nitrogen, expressed as milligrams per cent, are 253.4 and 140.0, respectively. 2. The blood of Samia walkeri has an osmotic pressure of 13.36 atmospheres at 0C. Its protein nitrogen is 628.58, and its non-protein nitrogen, 441.20 milligrams per cent. 3. The effects of isotonic chloride solutions of sodium, potassium, calcium, and magnesium and of distilled water on the heart beat of these two species were determined. The heart of the grasshopper failed to beat in isotonic solutions of KCl, MgCl2, or in distilled water. For both insects, sodium was found to be the least toxic ion. In the case of the grasshopper, calcium ranks next in order. In the case of the moth, potassium ranks next after sodium and is followed by calcium and magnesium. 4. The ratio of sodium to potassium in milligrams per cent, necessary for maintaining the normal heart beat of Chortophaga viridifasciata is 3 to 1, but it may be increased to at least 34 to 1 without any appreciable effects. The ratio of potassium to calcium necessary for maintaining the normal heart beat of this insect is 1 to 1, and may be increased to as much as 3 to 1. 5. The ratio of sodium to potassium, in milligrams per cent, necessary for maintaining the normal heart beat of Samia walkeri was found to be equal to or to exceed 1 to 13.8. The sodium content may be increased so that the ratio of sodium to potassium is 34 to 1 without any toxic effects. The ratios of potassium to calcium required for normal heart beat in this insect may be 1 to 1, 2 to 1, or 3 to 1. 6. The hearts of the grasshoppers beat normally in isotonic solutions having an osmotic pressure of 10.7 atmospheres. They beat equally well in solutions having an osmotic pressure of 13.4 atmospheres. The hearts of the cynthia pupae beat normally in isotonic solutions having an osmotic pressure of 13.36 atmospheres. However, they also beat normally in solutions having an osmotic pressure of 10.02 atmospheres. Therefore, although the blood of the cynthia moth and of the grasshopper have different osmotic pressures, their hearts are tolerant to solutions having the same tonicity. Because of this, and since the ratios of potassium to calcium necessary for maintaining normal heart beats of both insects are the same, solutions favorable to the grasshopper may also be favorable to the cynthia moth.

Barsa, Mary C.

1954-01-01

293

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

Microsoft Academic Search

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

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

1999-01-01

294

The crystal structure of hydrated sodium aluminate, NaAlO{sub 2}{center_dot}5/4H{sub 2}O, and its dehydration product  

SciTech Connect

The crystal structure of hydrated sodium aluminate, NaAlO{sub 2} {circ} 5/4H{sub 2}O, has been determined ab initio from synchrotron powder diffraction data. The compound crystallizes in the acentric primitive tetragonal space group P42{sub 1}m, with a = 10.53396(4) {Angstrom} and c = 5.33635(3) {Angstrom} at 27{degrees}C, and Z = 8. The structure consists of single layers parallel to (001) made of corner-sharing AlO{sub 4} tetrahedra, joined into 4- and 8-rings. The topology of the layers is that of framework 18 of Smith and Rinaldi. The layers are held together by two types of Na: one 6-coordinate, with nearly ideal octahedral geometry, and the second 7-coordinate, with a capped octahedral coordination. Two independent water molecules also occupy the interlayer regions, forming hydrogen bonds to framework O atoms. One oxygen of each AlO{sub 4} coordination sphere is a hydroxyl group, which points into the interlayer region. Dehydration of NaAlO{sub 2} - 5/4H{sub 2}O causes a structural transformation to NaAlO{sub 2}, surprisingly involving no intermediate phases. The crystal structure of dehydrated NaAlO{sub 2} was refined by the Rietveld method using laboratory powder X-ray data. This compound crystallizes in Pna2{sub 1}, with a = 5.3871(2) {Angstrom}, b = 7.0320(2) {Angstrom}, and c = 5.2180(2) {Angstrom} at 25{sub 0}C, Z = 4. The structure is based on a three-dimensional framework of corner- linked AlO{sub 4} tetrahedra and is isostructural to {beta}-NaFeO{sub 2}. NaAlO{sub 2} can be rehydrated to form NaAlO{sub 2}-5/4H{sub 2}O; the dehydration process, which is accompanied by large changes in framework topology, is reversible.

Kaduk, J.A.; Pei, S. [Amoco Corp., Naperville, IL (United States)] [Amoco Corp., Naperville, IL (United States)

1995-02-15

295

Unmodified CdSe Quantum Dots Induce Elevation of Cytoplasmic Calcium Levels and Impairment of Functional Properties of Sodium Channels in Rat Primary Cultured Hippocampal Neurons  

PubMed Central

Background The growing applications of nanotechnologic products, such as quantum dots (QDs), increase the likelihood of exposure. Furthermore, their accumulation in the bioenvironment and retention in cells and tissues are arousing increasing worries about the potentially harmful side effects of these nanotechnologic products. Previous studies concerning QD cytotoxicity focused on the reactive oxygen species produced by QDs. Cellular calcium homeostasis dysregulation caused by QDs may be also responsible for QD cytotoxicity. Meanwhile the interference of QDs with voltage-gated sodium channel (VGSC) current (INa) may lead to changes in electrical activity and worsen neurotoxicologic damage. Objective We aimed to investigate the potential for neurotoxicity of cadmium selenium QDs in a hippocampal neuronal culture model, focusing on cytoplasmic calcium levels and VGSCs function. Methods We used confocal laser scanning and standard whole-cell patch clamp techniques. Results We found that a) QDs induced neuron death dose dependently; b) cytoplasmic calcium levels were elevated for an extended period by QD treatment, which was due to both extracellular calcium influx and internal calcium release from endoplasmic reticulum; and c) QD treatment enhanced activation and inactivation of INa, prolonged the time course of activation, slowed INa recovery, and reduced the fraction of available VGSCs. Conclusion Results in this study provide new insights into QD toxicology and reveal potential risks of their future applications in biology and medicine.

Tang, Mingliang; Xing, Tairan; Zeng, Jie; Wang, Huili; Li, Chenchen; Yin, Shuting; Yan, Dan; Deng, Hongmin; Liu, Jin; Wang, Ming; Chen, Jutao; Ruan, Di-Yun

2008-01-01

296

Sequential acquisition of cacophony calcium currents, sodium channels and voltage-dependent potassium currents affects spike shape and dendrite growth during postembryonic maturation of an identified Drosophila motoneuron.  

PubMed

During metamorphosis the CNS undergoes profound changes to accommodate the switch from larval to adult behaviors. In Drosophila and other holometabolous insects, adult neurons differentiate either from respecified larval neurons, newly born neurons, or are born embryonically but remain developmentally arrested until differentiation during pupal life. This study addresses the latter in the identified Drosophila flight motoneuron 5. In situ patch-clamp recordings, intracellular dye fills and immunocytochemistry address the interplay between dendritic shape, excitability and ionic current development. During pupal life, changes in excitability and spike shape correspond to a stereotyped, progressive appearance of voltage-gated ion channels. High-voltage-activated calcium current is the first current to appear at pupal stage P4, prior to the onset of dendrite growth. This is followed by voltage-gated sodium as well as transient potassium channel expression, when first dendrites grow, and sodium-dependent action potentials can be evoked by somatic current injection. Sustained potassium current appears later than transient potassium current. During the early stages of rapid dendritic growth, sodium-dependent action potentials are broadened by a calcium component. Narrowing of spike shape coincides with sequential increases in transient and sustained potassium currents during stages when dendritic growth ceases. Targeted RNAi knockdown of pupal calcium current significantly reduces dendritic growth. These data indicate that the stereotyped sequential acquisition of different voltage-gated ion channels affects spike shape and excitability such that activity-dependent calcium influx serves as a partner of genetic programs during critical stages of motoneuron dendrite growth. PMID:24620836

Ryglewski, Stefanie; Kilo, Lukas; Duch, Carsten

2014-05-01

297

High potency inhibition of hERG potassium channels by the sodium-calcium exchange inhibitor KB-R7943  

PubMed Central

BACKGROUND AND PURPOSE KB-R7943 is an isothiourea derivative that is used widely as a pharmacological inhibitor of sodiumcalcium exchange (NCX) in experiments on cardiac and other tissue types. This study investigated KB-R7943 inhibition of hERG (human ether--go-go-related gene) K+ channels that underpin the cardiac rapid delayed rectifier potassium current, IKr. EXPERIMENTAL APPROACH Whole-cell patch-clamp measurements were made of hERG current (IhERG) carried by wild-type or mutant hERG channels and of native rabbit ventricular IKr. Docking simulations utilized a hERG homology model built on a MthK-based template. KEY RESULTS KB-R7943 inhibited both IhERG and native IKr rapidly on membrane depolarization with IC50 values of ?89 and ?120 nM, respectively, for current tails at ?40 mV following depolarizing voltage commands to +20 mV. Marked IhERG inhibition also occurred under ventricular action potential voltage clamp. IhERG inhibition by KB-R7943 exhibited both time- and voltage-dependence but showed no preference for inactivated over activated channels. Results of alanine mutagenesis and docking simulations indicate that KB-R7943 can bind to a pocket formed of the side chains of aromatic residues Y652 and F656, with the compound's nitrobenzyl group orientated towards the cytoplasmic side of the channel pore. The structurally related NCX inhibitor SN-6 also inhibited IhERG, but with a markedly reduced potency. CONCLUSIONS AND IMPLICATIONS KB-R7943 inhibits IhERG/IKr with a potency that exceeds that reported previously for acute cardiac NCX inhibition. Our results also support the feasibility of benzyloxyphenyl-containing NCX inhibitors with reduced potential, in comparison with KB-R7943, to inhibit hERG.

Cheng, Hongwei; Zhang, Yihong; Du, Chunyun; Dempsey, Christopher E; Hancox, Jules C

2012-01-01

298

[Frequency-related blocking of sodium channels in the membrane of isolated rat cardiomyocytes by the calcium antagonist verapamil].  

PubMed

Use-dependent blocking of sodium current in the membrane of single rat cardiomyocytes by verapamil (in the concentration range of 5-50 mumol/l) has been observed. The data obtained suggest that verapamil binding with sodium channels which are in the open or inactivated state underlies suppression of sodium current. PMID:2542101

Pidoplichko, V I; Verkhratski?, A N

1989-01-01

299

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

NASA Astrophysics Data System (ADS)

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 crystal spectra are generally comparable, suggesting similar vibrational structures. These crystals have structures based on tetrahedral aluminosilicate frameworks, and a similar molecular structure is suggested for the glasses, although it is noted that the Raman spectra do not directly characterize the aluminate polyhedra. Within the three glass series, our interpretation of the unresolved high-frequency bands shows the appearance of discrete bands near 1120, 1000, 930 and 890 cm -1 as the silica content is decreased. This is compared with the behaviour of high-frequency bands in simple silicate systems, and used to suggest that the four bands in the aluminosilicate systems are due to stretching vibrations of silicate tetrahedra bound to one, two, three and four aluminium atoms. The spectra of calcium, sodium, potassium and lithium aluminosilicate glasses with similar silica contents are compared, and interpreted by the above model. This is used to construct a simple model for the effect of metal cation on aluminosilicate molecular groups in the glass structure, consistent with the results of calorimetric studies on similar systems.

McMillan, Paul; Piriou, Bernard; Navrotsky, Alexandra

1982-11-01

300

A novel class of sodium\\/calcium exchanger inhibitor: design, synthesis, and structureactivity relationships of 3,4-dihydro-2(1 H)-quinazolinone derivatives  

Microsoft Academic Search

Design, synthesis, and structureactivity relationships of 3,4-dihydro-2(1H)-quinazolinone derivatives as inhibitors of the sodium\\/calcium (Na+\\/Ca2+) exchanger are discussed. These studies, based on a lead compound 9a, which was identified in our library, involved systematic modification of three regions and revealed that (1) the 3,4-dihydro-2(1H)-quinazolinone having a tertiary amino alkyl side chain at the 3-position is essential for activity, (2) a nonsubstituted

Hirohiko Hasegawa; Masami Muraoka; Mikiko Ohmori; Kazuki Matsui; Atsuyuki Kojima

2005-01-01

301

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

PubMed Central

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.

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

1999-01-01

302

Resistance of sodium polyphosphate-modified fly ash/calcium aluminate blend cements to hot H{sub 2}SO{sub 4} solution  

SciTech Connect

Sodium polyphosphate-modified Class F fly ash/calcium aluminate blend (SFCB) cements were prepared at room temperature and their resistance to hot acid erosion was evaluated by submerging them in H{sub 2}SO{sub 4} solution (pH 1.6) at 90 C. Sodium polyphosphate preferentially reacted with calcium aluminate cement (CAC) to form amorphous Ca(HPO{sub 4}).xH{sub 2}O and Al{sub 2}O{sub 3}.xH{sub 2}O gel, rather than fly ash. These amorphous reaction products, which ground the partially reacted and unreacted CAC and fly ash particles into a coherent mass, were responsible for strengthening and densifying the SFCB specimens at room temperature, playing an essential role in mitigating their acid erosion. In these cements, the extent of acid erosion depended primarily on the ratio of fly ash/CAC; namely, those with a higher ratio underwent a severe erosion. This effect was due to the formation of a porous structure, which allowed acid to permeate the cement easily, diminishing the protective activity of Ca(HPO{sub 4}).xH{sub 2}O and Al{sub 2}O{sub 3}.xH{sub 2}O gel against H{sub 2}SO{sub 4}.

Sugama, T.; Weber, L.; Brothers, L.E.

1999-12-01

303

Clathrate hydrates  

SciTech Connect

Clathrate hydrates or gas hydrates are solid solutions. Water molecules are linked through hydrogen bonding and create cavities (host lattice) that can enclose a large variety of molecules (guests). There is no chemical bonding between the host water molecules and the enclosed guest molecule. The clathrate hydrate crystal may exist at temperatures below as well as above the normal freezing point of water. Clathrate hydrates have been a source of problems in the energy industry because the conditions at which oil and gas are produced, transported, and processed are frequently suitable for clathrate hydrate formation. Naturally occurring clathrate hydrates in the earth, containing mostly methane, are regarded as a future energy resource. These methane hydrates, however, are potentially threatening to the global environment if they decompose due to the greenhouse effect. Several innovative separations based on clathrate hydrate formation with applications in a variety of industrial sectors have been examined in the laboratory and pilot-plant stage. This paper reviews the status of current knowledge on clathrate hydrates. The emphasis is on the aspects related to technological problems and opportunities that arise from the artificial or natural formation and decomposition of clathrate hydrates. However, a description of the fundamentals of formation, properties, and structure is also presented, and aspects related to the molecular simulation are discussed. Studies on calorimetric properties, orientational disorder, guest-guest interactions, and nuclear magnetic resonance are not reviewed, but literature references are made. Clathrate hydrates arouse great interest within chemical and petroleum engineering, chemistry, earth, and environmental sciences.

Englezos, P. (Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Chemical Engineering)

1993-07-01

304

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

Microsoft Academic Search

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

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

2008-01-01

305

Effects of altering calcium in haemodiluted pump primes on sodium and potassium in children undergoing open-heart operations  

Microsoft Academic Search

SummaryThe effects of low or normal calcium ion concentrations in the haemodiluted prime on plasma levels and urinary excretion of\\u000a monovalent cations were contrasted in 32 children undergoing open-heart operations with cardiopulmonary bypass (CPB).\\u000a \\u000a In patients in whom ionic calcium had been maintained near normal during bypass (Groups B and D, CaCl2 in prime), the intra-operative incidence of hyperkalaemia and

A. E. Johnston; I. C. Radde; H. I. A. Nisbet; J. Taylor

1972-01-01

306

Effects of A Voltage Sensitive Calcium Channel Blocker and A Sodium-Calcium Exchanger Inhibitor on Apoptosis of Motor Neurons in Adult Spinal Cord Slices  

PubMed Central

Objective: The apoptosis of motor neurons is a critical phenomenon in spinal cord injuries. Adult spinal cord slices were used to investigate whether voltage sensitive calcium channels and Na+/Ca2+ exchangers play a role in the apoptosis of motor neurons. Materials and Methods: In this experimental research, the thoracic region of the adult mouse spinal cord was sliced using a tissue chopper and the slices were incubated in a culture medium in the presence or absence of N/L type voltage sensitive calcium channels blocker (loperamide, 100 M) or Na+/Ca2+ exchangers inhibitor(bepridil, 20 M) for 6 hours. 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyl tetrazolium (MTT) staining was used to assess slice viability while morphological features of apoptosis in motor neurons were studied using fluorescent staining. Results: After 6 hours in culture, loperamideand bepridil not only increased slice viability, but also prevented motor neuron apoptosis and significantly increased the percentage of viable motor neurons in the ventral horns of the spinal cord. Conclusion: The results of this study suggest that voltage sensitive calcium channels and Na+/Ca2+ exchanger might be involved in the apoptosis of motor neurons in adult spinal cord slices.

Momeni, Hamid Reza; Jarahzadeh, Mahsa

2012-01-01

307

Dissolution kinetics of granular calcium carbonate in concentrated aqueous sodium dichromate solution at pH 6.0-7.0 and 110-130 degrees C.  

PubMed

An understanding of the factors controlling calcite dissolution is important for modeling geochemical cycles and impacts of greenhouse gases on climate, diagenesis of sediments, and sedimentary rocks. It also has practical significance in the investigation of behavior of carbonates in petroleum and natural gas reservoirs and in the preservation of buildings and monuments constructed from limestone and marble. A large number of papers have been published on dissolution kinetics of calcium carbonate in aqueous solutions. But few involved the near-equilibrium region, especially at elevated temperatures and in concentrated solutions. In this paper, the dissolution kinetics of calcium carbonate in concentrated aqueous sodium dichromate solutions at pH 6.0-7.0 and 110-130 degrees C were studied in a 2-L autoclave. The results indicate that the dissolution reaction is mix-controlled, with surface reaction as the prevailing factor. The concentration of calcium ions in solution hardly affects the dissolution rate, but carbon dioxide in the vapor phase inhibits the dissolution reaction. The dissolution rate can be expressed by R = k(1)a(2)(H+) + k(2), and the apparent activation energy is 55-84 kJ mol(-1). PMID:15567388

Wang, Tiangui; Li, Zuohu

2005-01-01

308

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

PubMed

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 24h 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

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

2014-07-01

309

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

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.

Moezizadeh, Maryam; Alimi, Azar

2014-01-01

310

Terahertz spectroscopy of concrete for evaluating the critical hydration level  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

311

Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 1226H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxidecalcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction  

NASA Astrophysics Data System (ADS)

In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 42H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 1226H 2O, monosulfate, Ca 4Al 2O 6(SO 4)14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 719H 2O. Ettringite is formed if sufficient CaSO 42H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 42H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170C 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.

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

2004-06-01

312

XPS and EPMA studies on self-healing mechanism of a protective film composed of hydrated cerium(III) oxide and sodium phosphate on zinc  

Microsoft Academic Search

A thin, protective film was prepared on a zinc electrode by coverage with a hydrated Ce2O3 layer and 0.0552 mg\\/cm2 of a Na3PO412H2O deposit layer and by drying the layers at 90 C for 23 h, as has been reported in the preceding paper. This film was highly self-healing at the scratched electrode in an aerated 0.5 M NaCl solution

Kunitsugu Aramaki

2003-01-01

313

Modulating drug release and matrix erosion of alginate matrix capsules by microenvironmental interaction with calcium ion.  

PubMed

Effect of calcium gluconate (CG) content on release of dextromethorphan hydrobromide (DMP), model drug, from capsules containing low and medium viscosity grades of sodium alginate (SA) was investigated in different dissolution media. Matrix erosion of the SA matrix capsules in distilled water and pH 7.4 phosphate buffer was compared. Molecular interaction of SA with calcium ion in surface gel layer of the SA matrix capsules was examined using Fourier transform infrared spectroscopy and differential scanning calorimetry. In distilled water and pH 7.4 phosphate buffer, DMP release rate depended on the viscosity grade of SA, whereas a comparable DMP release rate was found in 0.1N HCl. Incorporation of CG into the SA matrix capsules caused a faster drug release in acidic medium because CG acted as a channeling agent in the hydrated insoluble gel matrix of alginic acid. Interaction of calcium ions with carboxyl groups of SA could be formed in surface gel layer of hydrated matrix capsules in distilled water. This led to a more rigid matrix gel structure that caused a slower drug release and matrix erosion. In contrast, the extent of this interaction in pH 7.4 phosphate buffer was less than that in distilled water because the common ion effect and high concentration of sodium ion retarded the hydration of SA and the binding of calcium ions with carboxyl groups of SA. Thus, a small change in drug release and matrix erosion was observed. This finding suggests that microenvironmental interaction between hydrated SA and calcium ion in distilled water could be created in the formulations prepared using low compression force. Moreover, incorporation of CG could moderate drug release and matrix erosion of the SA matrix capsules. PMID:17270407

Pongjanyakul, Thaned; Puttipipatkhachorn, Satit

2007-08-01

314

Behavior of impurity metals in the fusion of magmatic rocks with a mixture of sodium carbonate and calcium oxide  

Microsoft Academic Search

The method of physicochemical simulation is used to calculate the equilibrium compositions of SiO2-Al2O3-(TiO2)-CaO-MgO-Fe2O3-(MnO)-Na2O-(Cr2O3)-(V2O5) systems in the temperature range of 12731473 K at various ratios of (Na2CO3 + CaO): rock. It is shown that the impurity metals are present in fusion products in the form of calcium polytitanate (Ca3Ti2O7), manganese(II, III) oxide (Mn3O4), chromium(III) oxide (Cr2O3), and calcium orthovanadate (Ca3V2O8).

N. P. Dergacheva; I. Z. Babievskaya; N. F. Drobot; A. V. Steblevskii; S. V. Fomichev; V. A. Krenev

2011-01-01

315

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

SciTech Connect

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.

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

2008-07-08

316

Interplay of Ca(2+) and Mg (2+) in sodium-calcium exchanger and in other Ca(2+)-binding proteins: magnesium, watchdog that blocks each turn if able.  

PubMed

Sodium-calcium exchange across plasma membrane is regulated by intracellular calcium ions. The sodium-calcium exchanger (NCX1) is activated by successive saturation of numerous Ca(2+)-binding sites located in the intracellular loop of the protein. The progressive saturation of the binding domain CBD12 by Ca(2+) results in a series of conformational changes of CBD12 as well as of entire NCX1 molecule. Like other soluble and membrane Ca(2+)-binding proteins, NCX1 can also be regulated by Mg(2+) that antagonises Ca(2+) at the level of divalent cation-binding sites. This chapter summarises data on Mg(2+) impacts in the cells. Regulatory action of Mg(2+) on intracellular Ca(2+)-dependent processes can be achieved due to changes of its cytoplasmic level, which take place in the range of [Mg(2+)](i) from 0.5 to 3 mM. Under normal conditions, these changes are ensured by activation of plasmalemmal Mg(2+) transport systems and by variations in ATP level in cytoplasm. In heart and in brain, some pathological conditions, such as hypoxia, ischemia and ischemia followed by reperfusion, are associated with an important increase in intracellular Ca(2+). The tissue damage due to Ca(2+) overload may be prevented by Mg(2+). The protective actions of Mg(2+) can be achieved due to its ability to compete with Ca(2+) for the binding sites in a number of proteins responsible for the rise in intracellular free Ca(2+), including NCX1, in case when the reverse mode of Na(+)/Ca(2+) exchange becomes predominant. Saturation of CBD12 by Mg(2+) results in important changes of NCX1 conformation. Modulating actions of Mg(2+) on the conformation of NCX1 were detected at a narrow range of Mg(2+) concentration, from 0.5 to 1 mM. These data support an idea that variations of intracellular Mg(2+) could modify transmembrane Ca(2+) movements ensured by NCX1. PMID:23224871

Levitsky, Dmitri O; Takahashi, Masayuki

2013-01-01

317

The dynamics of the sodium, potassium, calcium, magnesium contents in the fresh water mollusc zebra mussel Dreissenia polymorpha during stress  

Microsoft Academic Search

The sodium and magnesium concentration in the hemolymph of the zebra musselDreissenia polymorpha decreased by 25.1 and 25.6%, respectively, in 7.5 h after catching and transportation. One day later, the content of all\\u000a four cations studied in the molluscan body was significantly reduced. After 7 days, the decrease in the tissue concentration,\\u000a as compared to initial levels, was 2.7, 2.5,

V. I. Martemyanov

2000-01-01

318

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

SciTech Connect

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.

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

1987-05-01

319

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2010 CFR

...lye. The empirical formula is NaOH. Sodium hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The...

2010-01-01

320

21 CFR 184.1763 - Sodium hydroxide.  

Code of Federal Regulations, 2010 CFR

...lye. The empirical formula is NaOH. Sodium hydroxide is prepared commercially by the electrolysis of sodium chloride solution and also by reacting calcium hydroxide with sodium carbonate. (b) The...

2009-04-01

321

Combustion synthesis of calcium aluminates  

Microsoft Academic Search

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.

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

1996-01-01

322

The crystallization of calcium carbonate on porcine and human cardiac valves and the antimineralization effect of sodium alginate  

NASA Astrophysics Data System (ADS)

The use of biprosthetic valves remains limited, due to poor long-term durability, primarily as a result of tissue calcification. Porcine and human cardiac valve leaflets were found to be a substrate favoring the deposition of vaterite crystals from stable supersaturated solution at pH 8.5 at 25C. The apparent order for vaterite crystallization reaction was found to be n=1, suggesting a surface diffusion controlled mechanism. The crystallization was studied by the constant composition technique, thus making it possible for relatively large amounts of the overgrowth phase to be formed and identified exclusively as vaterite. Analysis of the initial rates of the reaction as a function of the solution supersaturation, according to the classical nucleation theory, yielded a value of 23.4 mJ m -2 for the surface energy of the growing phase and a three-ion cluster forming the critical nucleus. A novel "in vitro" anticalcification process based on the treatment of porcine and human heart valves with sodium alginate has been developed. This anticalcification procedure reduced mineralization of porcine and human valves up to 53% and 45%, respectively. Kinetic analysis according to a Langmuir type adsorption isotherm lead to the calculation of an affinity constant K aff=19.3104 mol -1 dm 3 for the adsorption of sodium alginate to the substrate.

Kanakis, J.; Malkaj, P.; Petroheilos, J.; Dalas, E.

2001-03-01

323

Comparison of a dual-phase fluoride toothpaste containing calcium, phosphate, and sodium bicarbonate with a regular fluoride toothpaste on calculus formation.  

PubMed

This clinical study compared the effect on dental calculus formation of a dual-phase fluoride dentifrice containing sodium bicarbonate, calcium, and phosphate with that of a regular dentifrice using a short-term clinical model in which calculus formation was facilitated. A total of 87 adult volunteers completed this study, which was a double-blind, parallel-group design, consisting of 2-week pretrial and trial periods separated by a washout period. A partial-mouth technique was used wherein the lower anterior teeth were protected from brushing by a custom-fitted toothshield, which doubled as an applicator for an undiluted dentifrice, twice daily. Calculus was measured on the labial/lingual surfaces of six lower anterior teeth by the Volpe-Manhold Index (V-MI). Subjects used a non-tartar-control dentifrice during the pretrial period to determine calculus formation rates, and these V-MI scores were used as baseline data for random allocation to either a control or test product for the trial period. Subjects who were accepted into the study, based on existing tartar deposits, readily formed calculus during the pretrial period using the toothshield method. During the trial period, subjects who were assigned the test dentifrice had comparable amounts of calculus accumulation to those who used the control dentifrice. However, subjects in the test dentifrice group had significantly lower (16%) calculus scores on lingual surfaces than those in the control group. Intragroup comparisons of V-MI data from the pretrial period with those from the trial period provided similar overall results to the comparisons between groups. This study demonstrated that a dual-phase baking soda dentifrice containing calcium and phosphate did not increase calculus accumulation relative to a regular dentifrice when used by adults with a propensity for developing calculus. PMID:15645907

Putt, Mark S; Milleman, Kimberly R; Milleman, Jeffery L; Ghassemi, Annahita

2004-09-01

324

Chemical characteristics of mineral trioxide aggregate and its hydration reaction  

PubMed Central

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.

2012-01-01

325

Comparative efficacy of dentifrice containing sodium monofluorophosphate + calcium glycerophosphate and non-fluoridated dentifrice: A randomized, double-blind, prospective study  

PubMed Central

Background: The efficacy of fluoridated dentifrices in caries prevention has been well documented and research into various formulations continues for a more effective dentifrice. This study evaluated the anti-caries and anti-plaque efficacy of a dentifrice containing sodium monofluorophosphate (1000 ppm) and calcium glycerophosphate, and compared it with a non-fluoridated dentifrice. Materials and Methods: A total of 595 school children (1215 years) were divided into test (302 children) and control (293 children) groups. The test group used the dentifrice containing sodium monofluorophosphate (1000 ppm) and calcium glycerophosphate, whereas the control group was given a placebo dentifrice. Oral examination for dental caries and plaque assessment was carried out at the start of the study and the children were followed up semiannually up to 18 months. Data were analyzed using repeated-measure analysis of variance (ANOVA) followed by one-way ANOVA. Results: The values for decayed missing filled teeth (DMFT) increased from baseline to 18 month examination from 4.432.03 and 4.672.25 (P=0.175) to 5.842.29 and 5.132.30 (P=0.001) for control and test groups, respectively. Similarly, the increase in decayed missing filled surface (DMFS) values were from 6.424.10 and 7.064.77 (P=0.082) to 8.644.51 and 7.925.07 (P=0.095) for test and control groups, respectively. The mean DMFT and DMFS values increased for both the groups; however, the increase was less in test group as compared to control group. The baseline plaque score reduced from 2.940.72 and 2.910.72 (P=0.679), respectively, for control and test groups to 1.330.46 and 0.910.38 (P<0.001), respectively, at 18 month examination. Conclusion: Results revealed that the test dentifrice was effective in inhibiting the progression of plaque and control of dental caries as compared to the placebo dentifrice.

Damle, Satyawan G.; Deoyani, D; Bhattal, Hiteshwar; Yadav, Renu; Lomba, Ashish

2012-01-01

326

Simultaneous determination of timolol maleate, rosuvastatin calcium and diclofenac sodium in pharmaceuticals and physiological fluids using HPLC-UV.  

PubMed

A novel HPLC-UV method was developed for the simultaneous determination of timolol (TM), rosuvastatin (RST), and diclofenac sodium (DS) in pharmaceuticals, human plasma and aqueous humor using naproxen sodium as internal standard (IS). The target compounds were analyzed on Hypersil BDS C(18) column (250 mm 4.6 mm, 5 ?m), applying 0.2% triethylamine (TEA) and acetonitrile (ACN) (40:60, v/v), in isocratic mode as mobile phase, pH 2.75 adjusted with 85% phosphoric acid at a flow rate of 1 ml/min. The column oven temperature was kept at 45C and the peak response was monitored at 284 nm after injecting a 50 ?l sample into HPLC system. The direct liquid-liquid extraction procedure was applied to human plasma and bovine aqueous humor samples using mobile phase as an extraction solvent after deproteination with methanol. The different HPLC experimental parameters were optimized and the method was validated according to standard guidelines. The recoveries of the suggested method in human plasma were 98.72, 96.04, and 95.14%, for TM, RST, and DS, while in aqueous humor were 94.99, and 98.23%, for TM, and DS, respectively. The LOD values were found to be 0.800, 0.500, and 0.250 ng/ml, for TM, RST, and DS, respectively, while their respective LOQ values were 2.00, 1.50, and 1.00 ng/ml. The co-efficient of variation (CV) were in the range of 0.1492-1.1729% and 1.0516-4.0104%, for intra-day and inter-day studies, respectively. The method was found accurate in human plasma and bovine aqueous humor and will be applied for the quantification of these compounds in plasma, and aqueous humor samples using animal models and in pharmaceuticals. PMID:21963479

Nasir, Fazli; Iqbal, Zafar; Khan, Abad; Ahmad, Lateef; Shah, Yasar; Khan, Amir Zada; Khan, Jamshaid Ali; Khan, Salimullah

2011-11-15

327

Sodium- and Calcium-Dependent Spike Potentials in the Secretory Neuron Soma of the X-Organ of the Crayfish  

PubMed Central

Membrane characteristics of neuron somata in the medulla terminalis ganglionic X-organ of crayfish have been investigated with intracellular glass microelectrodes. The soma membrane developed action potentials with 1020 mv of overshoot. Delayed rectification appeared at 1020 mv above resting membrane potential. In 50% of the neuron somata examined, action potentials were observed in Na-free medium or TTX medium. The peak potential level of the spike in these media depended on the extracellular concentration of Ca ion. It increased with the Ca concentration. In low calcium media, the peak potential level of the spike varied with Na concentration. Action potentials of the X-organ-sinus gland tract disappeared after bathing in Na-free or TTX medium, suggesting that the conductive action potential was dependent on Na ions. From these results, it is concluded that there are two systems in the neuron soma, one of which responds to the Na ion and the other, to the Ca ion. Inhibitory innervation of the X-organ by the cerebral ganglion was manifested by IPSP's when the optic peduncle was stimulated. A postulated connection between the Ca-dependent spike and the release of hormone in X-organ neuron somata is discussed.

Iwasaki, Shizuko; Satow, Youko

1971-01-01

328

Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation  

NASA Astrophysics Data System (ADS)

Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR. Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.67.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg body weight. Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly ( p?0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly ( p?0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly ( p?0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly ( p?0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values. The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.

Zorbas, Yan G.; Kakurin, Vassily J.; Kuznetsov, Nikolai A.; Yarullin, Vladimir L.

2002-06-01

329

Involvement of the potassium-dependent sodium/calcium exchanger gene product NCKX2 in the brain insult induced by permanent focal cerebral ischemia.  

PubMed

Sodium/calcium exchangers are neuronal plasma membrane transporters, which by coupling Ca2+ and Na+ fluxes, may play a relevant role in brain ischemia. The exchanger gene superfamily comprises two arms: the K+-independent (NCX) and K+-dependent (NCKX) exchangers. In the brain, three different NCX (NCX1, NCX2, NCX3) and three NCKX (NCKX2, NCKX3, NCKX4) family members have been described. Up to now, no sutides about the role played by NCKX proteins in cerebral ischemia have been published. The aim of the present study was to investigate the role of NCKX2 in an in vivo model of permanent middle cerebral artery occlusion (pMCAO). The role of this protein in the development of ischemic damage was assessed by knocking-down its expression with an antisense oligodeoxynucleotide (AS-ODN), intracerebroventricularly infused by an osmotic minipump for 48 h, starting from 24 h before pMCAO. The results showed that NCKX2 knocking-down by using antisense strategy increased the extent of the ischemic lesion. The results of this study suggest that NCKX2 could exert a neuroprotective effect during ischemic injury. PMID:17446491

Cuomo, Ornella; Pignataro, Giuseppe; Gala, Rosaria; Boscia, Francesca; Tortiglione, Anna; Molinaro, Pasquale; Di Renzo, Gianfranco; Lytton, Jonathan; Annunziato, Lucio

2007-03-01

330

Hydrothermal treatment of naturally contaminated maize in the presence of sodium metabisulfite, methylamine and calcium hydroxide; effects on the concentration of zearalenone and deoxynivalenol.  

PubMed

Fusarium toxin-contaminated ground maize was hydrothermally treated in the presence of different combinations of chemicals in order to simultaneously reduce zearalenone (ZEA) and deoxynivalenol (DON) concentrations. Treatments were carried out in a laboratory conditioner at 80 C and 17 % moisture. Six different treatments were performed, consisting of 3 doses of methylamine (MMA; 2.5, 5 and 10 g/kg maize) at a constant dose of 5 g sodium metabisulfite (SBS)/kg, either with or without the addition of 20 g calcium hydroxide (Ca(OH)2)/kg. The used maize was contaminated with approximately 45.99 mg DON/kg and 3.46 mg ZEA/kg. Without the addition of Ca(OH)2, DON reductions reached approximately 82% after 1-min treatment and the toxin disappeared nearly completely after 10 min when 2.5 or 5 g MMA were applied. ZEA concentrations were only marginally affected. In the presence of Ca(OH)2, reductions in DON concentrations were lower, but were enhanced by increasing doses of MMA. ZEA concentrations were reduced by 72, 85 and 95% within the first 5 min of the treatment at MMA dosages of 2.5, 5 and 10 g/kg maize, respectively. The application of SBS in combination with a strong alkaline during hydrothermal treatment seems to be a promising approach to simultaneously decontaminate even high amounts of DON and ZEA in ground maize and may contribute to reduce the toxin load of diets. PMID:23536360

Rempe, Inga; Kersten, Susanne; Valenta, Hana; Dnicke, Sven

2013-08-01

331

Determination of calcium, magnesium, sodium, and potassium in foodstuffs by using a microsampling flame atomic absorption spectrometric method after closed-vessel microwave digestion: method validation.  

PubMed

This paper describes a validation process in compliance with the NFIEN ISO/IEC 17025 standard for the determination of the macrominerals calcium, magnesium, sodium, and potassium in foodstuffs by microsampling with flame atomic absorption spectrometry after closed-vessel microwave digestion. The French Standards Commission (Agence Francaise de Normalisation) standards NF V03-110, NF EN V03-115, and XP T-90-210 were used to evaluate this method. The method was validated in the context of an analysis of the 1322 food samples of the second French Total Diet Study (TDS). Several performance criteria (linearity, LOQ, specificity, trueness, precision under repeatability conditions, and intermediate precision reproducibility) were evaluated. Furthermore, the method was monitored by several internal quality controls. The LOQ values obtained (25, 5, 8.3, and 8.3 mg/kg for Ca, Mg, Na, and K, respectively) were in compliance with the needs of the TDS. The method provided accurate results as demonstrated by a repeatability CV (CVr) of < 7% and a reproducibility CV (CVR) of < 12% for all the elements. Therefore, the results indicated that this method could be used in the laboratory for the routine determination of these four elements in foodstuffs with acceptable analytical performance. PMID:21313817

Chekri, Rachida; Nol, Laurent; Vastel, Christelle; Millour, Sandrine; Kadar, Ali; Gurin, Thierry

2010-01-01

332

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

PubMed

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

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

2013-09-01

333

Thermodynamics of calcium silicate hydrates, development of a database to model concrete dissolution at 25C using the EQ3/6 geochemical modeling code  

SciTech Connect

Examination of the ability to model aqueous systems of interest to the repository proposed by the Yucca Mountain Project has revealed an historical deficit in the ability to model complex watermaterial systems that contain ordinary Portland cement (OPC) at elevated temperature (e.g., Bruton et al., 1994; Meike et al., 1994). One of the reasons is that cement chemistry typically concentrates on two issues of importance to the concrete industry: the hydration of cement powder, which contains reactive phases that do not persist in the cured concrete, and the causes of mechanical degradation at earth surface temperatures such as delayed ettringite formation and alkali silica reaction. Such modeling capability is not available in the open literature, even from applications that might have developed high temperature approaches, such as deep drilling for oil and geothermal resource recovery. The ability to simulate the interaction between concrete, as it evolves over time, and water has become more critical as repository designers begin to consider the incorporation of OPC materials in the emplacement drifts. The Yucca Mountain Project is unique among the high-level radioactive waste repository projects in the world in terms of the need to understand and predict processes in excess of 100C (see, e.g., Meike, 1997). Our aim has been to develop this capability in the area of aqueous chemistry.

Clodic, L.; Meike, A.

1997-08-18

334

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

...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...

2012-07-01

335

Hydration of purolite S950 ion exchanger in deprotonated forms  

NASA Astrophysics Data System (ADS)

A quantitative evaluation of the degree of hydration, including the ratios of water with different energies in the phase of the aminophosphonic exchanger Purolite S950 in sodium, copper, and nickel forms is conducted. The changes in the Gibbs free energy and enthalpies of hydration and dehydration are determined. It is found that the amount of bound water decreases upon the transition from nickel to copper, especially to the sodium forms of the ion exchanger, and that changes in the Gibbs energy and enthalpy are greatest upon the hydration of the sodium form of polyampholytes.

Gapeev, A. A.; Bondareva, L. P.; Buzin, M. I.; Kornienko, T. S.

2013-05-01

336

Effectiveness of a calcium sodium phosphosilicate containing prophylaxis paste in reducing dentine hypersensitivity immediately and 4 weeks after a single application: a double-blind randomized controlled trial  

PubMed Central

Aims The aim of this single-site, randomized, controlled, double-blind, 3-arm parallel study was to determine the effectiveness of a prophylaxis paste containing 15% calcium sodium phosphosilicate (CSPS; NovaMin) with and without fluoride in reducing dentine hypersensitivity immediately after a single application and 28 days following dental scaling and root planing. Materials & Methods Overall, 151 subjects were enrolled in this study. All subjects received a scaling and root planing procedure followed by a final prophylaxis step using one of three different prophylaxis pastes: Test-A (15% NovaMin and NaF), Test-B (15% NovaMin) and a control. Dentine hypersensitivity was assessed by tactile stimulus (Yeaple Probe) and by air blast (Schiff scale) at baseline, immediately after and 28 days after a prophylaxis procedure. One hundred and forty-nine subjects completed the study. Results Subjects having received the test prophylaxis pastes showed statistically lower (anova, p < 0.05) dentine hypersensitivity compared with the control group immediately after the prophylaxis procedure (Yeaple Probe: Test-A = 20.9 12.6, Test-B = 22.7 12.9, Control=11.2 3.1; Schiff score: Test-A = 1.1 0.6, Test-B = 1.1 0.6, Control = 2.0 0.7) and after 28 days (Yeaple probe: Test-A = 21.5 11.9, Test-B = 20.6 11.3, Control = 11.8 6.0; Schiff score: Test-A = 1.0 0.6, Test-B = 1.0 0.6, Control = 2.0 0.7). Conclusions In conclusion, the single application of both fluoridated and non-fluoridated prophylaxis pastes containing 15% CSPS (NovaMin) provided a significant reduction of dentine hypersensitivity up to at least 28 days.

Neuhaus, Klaus W; Milleman, Jeffery L; Milleman, Kimberly R; Mongiello, Kimberly A; Simonton, Thomas C; Clark, Courtney E; Proskin, Howard M; Seemann, Rainer

2013-01-01

337

Identification of the sodium-calcium exchanger as the major ricin-binding glycoprotein of bovine rod outer segments and its localization to the plasma membrane  

SciTech Connect

After neuraminidase treatment the Na{sup +}/Ca{sup 2+} exchanger of bovine rod outer segments was found to specifically bind Ricinus communis agglutinin. SDS gel electrophoresis and Western blotting of ricin-binding proteins purified from rod outer segment membranes by lectin affinity chromatography revealed the existence of two major polypeptides of M{sub r} 215K and 103K, the former of which was found to specifically react with PMe 1B3, a monoclonal antibody specific for the 230-kDa non-neuraminidase-treated Na{sup +}/Ca{sup 2+} exchanger. Reconstitution of the ricin affinity-purified exchanger into calcium-containing liposomes revealed that neuraminidase treatment had no significant effect on the kinetics of Na{sup +}/Ca{sup 2+} exchange activation by sodium. The authors further investigated the density of the Na{sup +}/Ca{sup 2+} exchanger in disk and plasma membrane preparations using Western blotting, radioimmunoassays, immunoelectron microscopy, and reconstitution procedures. The results indicate that the Na{sup +}/Ca{sup 2+} exchanger is localized in the rod photoreceptor plasma membrane and is absent or present in extremely low concentrations in disk membranes, as they have previously shown to be the case for the cGMP-gated cation channel. Previous reports describing the existence of Na{sup +}/Ca{sup 2+} exchange activity in rod outer segment disk membrane preparations may be due to the fusion of plasma membrane components and/or the presence of contaminating plasma membrane vesicles.

Reid, D.M.; Molday, R.S. (Univ. of British Columbia, Vancouver (Canada)); Friedel, U.; Cook, N.J. (Max-Planck Institut fur Biophysik, Frankfurt (West Germany))

1990-02-13

338

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

PubMed Central

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 1H15N 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 1H15N 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 (Y12I51) were affected, and with further additions of NaCl, residues near the C-terminus (L141T171) 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.

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

2009-01-01

339

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

PubMed

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

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

2013-08-01

340

Activation of sodium-dependent glutamate transporters regulates the morphological aspects of oligodendrocyte maturation via signaling through calcium/calmodulin-dependent kinase II?'s actin-binding/-stabilizing domain.  

PubMed

Signaling via the major excitatory amino acid glutamate has been implicated in the regulation of various aspects of the biology of oligodendrocytes, the myelinating cells of the central nervous system (CNS). In this respect, cells of the oligodendrocyte lineage have been described to express a variety of glutamate-responsive transmembrane proteins including sodium-dependent glutamate transporters. The latter have been well characterized to mediate glutamate clearance from the extracellular space. However, there is increasing evidence that they also mediate glutamate-induced intracellular signaling events. Our data presented here show that the activation of oligodendrocyte expressed sodium-dependent glutamate transporters, in particular GLT-1 and GLAST, promotes the morphological aspects of oligodendrocyte maturation. This effect was found to be associated with a transient increase in intracellular calcium levels and a transient phosphorylation event at the serine (S)(371) site of the calcium sensor calcium/calmodulin-dependent kinase type II? (CaMKII?). The potential regulatory S(371) site is located within CaMKII?'s previously defined actin-binding/-stabilizing domain, and phosphorylation events within this domain were identified in our studies as a requirement for sodium-dependent glutamate transporter-mediated promotion of oligodendrocyte maturation. Furthermore, our data provide good evidence for a role of these phosphorylation events in mediating detachment of CaMKII? from filamentous (F)-actin, and hence allowing a remodeling of the oligodendrocyte's actin cytoskeleton. Taken together with our recent findings, which demonstrated a crucial role of CaMKII? in regulating CNS myelination in vivo, our data strongly suggest that a sodium-dependent glutamate transporter-CaMKII?-actin cytoskeleton axis plays an important role in the regulation of oligodendrocyte maturation and CNS myelination. GLIA 2014;62:1543-1558. PMID:24866099

Martinez-Lozada, Zila; Waggener, Christopher T; Kim, Karam; Zou, Shiping; Knapp, Pamela E; Hayashi, Yasunori; Ortega, Arturo; Fuss, Babette

2014-09-01

341

Olefin hydration  

SciTech Connect

An improved process for the hydration of olefins to alcohols is described wherein the improvement comprises contacting said olefins with the catalytic composition comprising a perfluorinated ion-exchange polymer containing sulfonic acid groups supported on an inert carrier wherein said carrier comprises calcined shot coke with a mean pore diameter of about 1,000 Angstroms in the presence of water at a temperature of from about 180 C to about 250 C.

Butt, M.H.D.; Waller, F.J.

1993-08-03

342

Influence of A-type Zeolite on Methane Hydrate Formation  

Microsoft Academic Search

The porous medium has an important effect on hydrate formation. In this paper, the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system. The results show that A-type zeolite can influence methane hydrate formation. At the temperature of 273.5 K and pressure of 8.3

Xiaoya ZANG; Jianwei DU; Deqing LIANG; Shuanshi FAN; Cuiping TANG

2009-01-01

343

What drives the precipitation of long-chain calcium carboxylates (soaps) in aqueous solution?  

PubMed

The interaction of sodium octanoate, decanoate or dodecanoate with calcium(ii) in aqueous solutions has been studied using turbidity, conductivity and potentiometric measurements. These show a marked alkyl chain length dependence on the behaviour. At the calcium concentration used (1.0 mM), there is little interaction with the octanoate, the decanoate shows initially formation of a 1:1 complex, followed by precipitation, while the dodecanoate precipitates at low surfactant concentrations. The solid calcium carboxylates were prepared, and show lamellar, bilayer structures with planes of calcium(II) ions coordinated to carboxylate groups through bidentate chelate linkages. Thermogravimetry and elemental analyses indicate the presence of coordinated water with the calcium decanoate but not with longer chain carboxylates. The results of both the solution and solid state studies suggest that precipitation of long-chain carboxylates depends on a balance between hydration effects and hydrophobic (largely van der Waals') interactions. Electrostatic effects make little energetic contribution but play the important structural role of ordering the carboxylate anions before precipitation. Differences are observed in the interactions between calcium(II) and long chain alkylcarboxylates and alkylsulfates, and are interpreted in terms of stronger binding to the metal of the carboxylate group. A general mechanism is proposed for calcium carboxylate precipitation from aqueous solution based on this and previous studies. PMID:22513819

Pereira, Rui F P; Valente, Artur J M; Fernandes, Mariana; Burrows, Hugh D

2012-05-28

344

Standard enthalpies of formation of francium hydroxide hydrates  

Microsoft Academic Search

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

Burylev

1995-01-01

345

Effect of additives on formation of natural gas hydrate  

Microsoft Academic Search

The formation of natural gas hydrate (NGH) is studied in this work. Kinetics data of hydrate formation with no agitation were collected at various concentrations of the aqueous solutions with different additives such as alkylpolyglucside, sodium dodecyl benzene sulfonate and potassium oxalate monohydrate. Various kinds of additive increased the formation rates of NGH and its storage capacity and reduced the

C. S Zhang; S. S Fan; D. Q Liang; K. H Guo

2004-01-01

346

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

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?, UN+NSC, UN+Na?S?O? and UN+CaCl? and incubated at 22C 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? was accumulated over 50 d (maximum 93 mg kg?) 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

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

2011-03-01

347

Hydrates of hydrocarbons  

SciTech Connect

Gas hydrates are solid crystalline compounds of water and methane that are similar to snow. They form in and block gas wells and lines and cause fouling of heat exchangers when the gas is cooled. Here, finally, is long-awaited information detailing the successful methods for not only removing gas hydrates but also for preventing their reforming. This book addresses methods of hydrate removal and, most importantly, prevention of hydrate build-up. New topics of using hydrate properties for new technologies and production of gas from natural gas hydrate deposits are also discussed. Information specific to hydrate formation in gas includes: conditions and area of hydrate-carrying rock; estimating gas amounts in gas hydrate deposits; the role of natural gas hydrates in global changes; the physical principles and models of gas hydrate deposit development; results of the Messoyakhi gas hydrate field development; and hydrates in space. Contents includes: Physical-chemical aspects; Properties of hydrates; Mechanism of hydrate formation; Technological appellations of hydrates; Natural hydrates of gases; Conclusion; and Bibliography.

Makogon, Y.F. [Moscow Petroleum Inst. (Russian Federation)

1997-12-31

348

The influence of some amino acids on calcium oxalate dihydrate transformation  

NASA Astrophysics Data System (ADS)

The influence of histidine (His), serine (Ser), tryptophan (Trp), glutamic acid (Glu) and ornithine (Orn) on the formation of calcium oxalate hydrates and the transformation of calcium oxalate dihydrate (COD) to the thermodynamically stable monohydrate (COM) has been studied. Simultaneous production of two hydrates (COM and COD) was initiated by mixing sodium oxalate solutions containing the respective amino acid with equal volumes of calcium chloride solutions. A combination of optical microscopy, X-ray diffraction, thermogravimetric analysis, size distribution measurements and atomic absorption spectroscopy were used to characterize the processes involved. The examined amino acids have a specific effect on the nucleation of calcium oxalates: Trp and His promote the formation of COD over COM while the others favour the formation of COM. The presence of Trp and Ser influenced the morphology of COD crystals. The processes comprising the transformation, the dissolution of COD and the growth of COM, were examined separately. The corresponding growth and dissolution rates have been determined and it was found that Trp and Ser affected the transformation kinetics by changing the rate controlling mechanism of COD dissolution from diffusion to a surface controlled reaction.

Bre?evi?, Lj.; Kralj, D.

1986-12-01

349

Clathrate hydrates in nature.  

PubMed

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

Hester, Keith C; Brewer, Peter G

2009-01-01

350

The Dependence of the Dissociation Rate of Methane-SDS Hydrate below Ice Point on Its Manners of Forming and Processing  

Microsoft Academic Search

The dissociation rates of methane hydrates formed with and without the presence of sodium dodecylsulfate (methane-SDS hydrates), were measured under atmospheric pressure and temperatures below ice point toinvestigate the influence of the hydrate production conditions and manners upon its dissociation kinetic behavior. The experimental results demonstrated that the dissociation rate of methane hydrate below ice point is strongly dependent on

Xiulin WANG; Guangjin CHEN; Changyu SUN; Lanying YANG; Qinglan MA; Jun CHEN; Peng LIU; Xu-long TANG; Huanwei ZHAO; Weidong CHEN

2009-01-01

351

Reactions of fly ash with calcium aluminate cement and calcium sulphate  

Microsoft Academic Search

The hydration processes in the ternary system fly ash\\/calcium aluminate cement\\/calcium sulphate (FA\\/CAC\\/C$) at 20C were investigated; six compositions from the ternary system FA\\/CAC\\/C$ were selected for this study. The nature of the reaction products in these pastes were analysed by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). At four days reaction time, the main hydration reaction product in these

Luca Fernndez-Carrasco; E. Vzquez

2009-01-01

352

Stoichiometry of Calcium Medicines  

NASA Astrophysics Data System (ADS)

Students have a greater appreciation of the principles of chemistry if they can see the relevance to their lives. Calcium supplements provide an excellent context in which to review most of the core content of general chemistry, namely, stoichiometry, concentration units, hydration of salts, inorganic and organic salts, physiological importance of elements, resonance in ions, geometry of polyatomic ions, and isomerism. A set of questions covering the cited topics and the corresponding answers are presented to encourage the critical thinking by students.

Pinto, Gabriel

2005-10-01

353

Calcium stone disease: a multiform reality.  

PubMed

In calcium renal stones, calcium oxalate and calcium phosphate in various crystal forms and states of hydration can be identified. Calcium oxalate monohydrate (COM) or whewellite and calcium oxalate dihydrate (COD) or weddellite are the commonest constituents of calcium stones. Calcium oxalate stones may be pure or mixed, usually with calcium phosphate or sometimes with uric acid or ammonium urate. The aim of this study was to compare the clinical and urinary patterns of patients forming calcium stones of different composition according to infrared spectroscopic analysis in order to obtain an insight into their etiology. The stones of 84 consecutive calcium renal stone formers were examined by infrared spectroscopy. In each patient, a blood sample was drawn and analysed for serum biochemistry and a 24-h urine sample was collected and analysed for calcium, phosphate, oxalate, citrate and other electrolytes. We classified 49 patients as calcium oxalate monohydrate (COM) stone formers, 32 as calcium oxalate dihydrate (COD) stone formers and three as apatite stone formers according to the main component of their stones. Patients with COM stones were significantly older than patients with COD stones (P < 0.002). Mean daily urinary calcium and urinary saturation with respect to calcium oxalate were significantly lower in patients with COM than in those with COD stones (P < 0.000). Patients with calcium oxalate stones containing a urate component (< or = 10%) presented with higher saturation (P < 0.012) with respect to uric acid in their urine (and lower with respect to calcium oxalate and calcium phosphate, respectively P < 0.024 and P < 0.003) in comparison with patients without a urate component in the stone. Patients with calcium oxalate stones with a calcium phosphate component (> or = 15%) showed higher (P < 0.0016) urinary saturation levels with respect to calcium phosphate (and lower with respect to uric acid (P < 0.009), compared with patients forming stones without calcium phosphate or with a low calcium phosphate component. Patients with calcium stones mixed with urate had a significantly lower urinary pH (P < 0.002) and urinary calcium (P < 0.000), and patients with calcium phosphate >15%, higher urinary pH (P < 0.004) and urinary calcium (P < 0.000). In conclusion, in the evaluation of the individual stone patient, an accurate analysis of the stone showing its exact composition and the eventual presence of minor components of the stone is mandatory in order to plan the correct prophylactic treatment. Patients with "calcium stones" could require various approaches dependent on the form and hydration of the calcium crystals in their stones, and on the presence of "minor" crystalline components that could have acted as epitaxial factors. PMID:15714335

Trinchieri, Alberto; Castelnuovo, Chiara; Lizzano, Renata; Zanetti, Giampaolo

2005-06-01

354

Caffeine, urinary Calcium, Calcium Metabolism and Bone1'2  

Microsoft Academic Search

Oral doses of caffeine increase the urinary excretion of calcium, magnesium, sodium and chloride for at least 3 h after consumption. The hypercalciuric effect can be blocked by adenosine receptor agonists. The effect is proportional to dose per lean body mass and no adaptation to the urinary losses occurs with continuing consumption of caffeine. Uncompensated losses of calcium would be

LINDA K. MASSEY; ANDSUSAN J. WHITING

355

Current understanding of cellulose ethers impact on the hydration of C 3A and C 3A-sulphate systems  

Microsoft Academic Search

The impact of cellulose ethers (CE) on C3A hydration was examined to support the understanding of the retarding effect of CE on cement hydration. In this sense, we successively studied the CE adsorption on ettringite and calcium hydroaluminates, and then the CE influence during C3A hydration in presence or absence of calcium sulphate. We emphasized a phase-specific adsorption of CE

J. Pourchez; P. Grosseau; B. Ruot

2009-01-01

356

Effects of Calcium Chloride on Growth, Membrane Permeability and Root Hydraulic Conductivity in Two Atriplex Species Grown at High (Sodium Chloride) Salinity  

Microsoft Academic Search

Calcium (Ca) has an important role in plant physiology, including involvement in the responses to salt stress, and controls numerous processes. To overcome the negative impact of high salinity, the addition of supplemental Ca to the growth medium as an ameliorative agent could be necessary. Atriplex halimus subsp. schweinfurthii and Atriplex canescens subsp. linearis were grown in hydroponic conditions to

Bouzid Nedjimi; Youcef Daoud

2009-01-01

357

Inhibition of Reverse-Mode Sodium-Calcium Exchanger Activity and Apoptosis by Levosimendan in Human Cardiomyocyte Progenitor Cell-Derived Cardiomyocytes after Anoxia and Reoxygenation  

PubMed Central

Levosimendan, a known calcium sensitizer with positive inotropic and vasodilating properties, might also be cardioprotective during ischemia-reperfusion (I/R) insult. Its effects on calcium homeostasis and apoptosis in I/R injury remain unclear. Na+/Ca2+ exchanger (NCX) is a critical mediator of calcium homeostasis in cardiomyocytes, with reverse-mode NCX activity responsible for intracellular calcium overload and apoptosis of cardiomyocytes during I/R. We probed effects and underlying mechanisms of levosimendan on apoptosis and NCX activity in cultured human cardiomyocyte progenitor cells (CPC)-derived cardiomyocytes undergoing anoxia-reoxygenation (A/R), simulating I/R in vivo. Administration of levosimendan decreased apoptosis of CPC-derived cardiomyocytes induced by A/R. The increase in reverse-mode NCX activity after A/R was curtailed by levosimendan, and NCX1 was translocated away from the cell membrane. Concomitantly, endoplasmic reticulum (ER) stress response induced by A/R was attenuated in CPC-derived cardiomycytes treated with NCX-targeted siRNA or levosimendan, with no synergistic effect between treatments. Results indicated levosimendan inhibited reverse-mode NCX activity to protect CPC-derived cardiomyocytes from A/R-induced ER stress and cell death.

Li, Ping-Chun; Yang, Ya-Chi

2014-01-01

358

Clinical experience with sodium cellulose phosphate  

Microsoft Academic Search

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

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

1983-01-01

359

Co-Localization of Sodium Channel Na[v]1.6 and the Sodium--Calcium Exchanger at Sites of Axonal Injury in the Spinal Cord in EAE  

ERIC Educational Resources Information Center

Axonal degeneration contributes to the development of non-remitting neurological deficits and disability in multiple sclerosis, but the molecular mechanisms that underlie axonal loss in multiple sclerosis are not clearly understood. Studies of white matter axonal injury have demonstrated that voltage-gated sodium channels can provide a route for

Craner, Matthew J.; Hains, Bryan C.; Lo, Albert C.; Black, Joel A.; Waxman, Stephen G.

2004-01-01

360

Natural Gas Hydrates  

Microsoft Academic Search

This paper reports on gas clathrates (commonly called hydrates), which are crystalline compounds that occur when water form a cage-like structure around smaller guest molecules. Gas hydrates of interest to the natural gas hydrocarbon industry are composed of water and eight molecules: methane, ethane, propane, isobutane, normal butane, nitrogen, carbon dioxide, and hydrogen sulfide. Hydrate formation is possible in any

E. Sloan Jr.; E. D. Jr

1991-01-01

361

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

Microsoft Academic Search

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

Masakazu Iwamoto; Shinichiro Nakamura; Hideto Kusano; Shuichi Kagawa

1986-01-01

362

depth measurement temperature measurement pressure measurement conductivity measurement (Salinity measurement TDS measurement) Oxygen Concentration measurement (Oxygen saturation measurement) pH-value measurement Red-ox-potential ORP measurement turbidity measurement (TSS measurement) measurement ion selective electrode (nitrate chloride ammonium potassium calcium sodium fluoride gas ammonia) fluorescence measurements (chlorophyll a cyanobacteria rhodamine ) optical oxygen measurements.  

EPA Pesticide Factsheets

Did you mean: depth measurement temperature measurement pressure measurement conductivity measurement (Salinity measurement TDS measurement) Oxygen Concentration measurement (Oxygen saturation measurement) pH-value measurement Red-ox-potential ORP measurement turbidity measurement (TSS measurement) measurement ion selective electrode (nitrate chloride ammonium potassium calcium sodium fluoride gas ammonia) fluorescence measurements (chlorophyll a cyanobacteria rhodamine ) optical oxygen measurements. ?

363

21 CFR 184.1229 - Calcium stearate.  

Code of Federal Regulations, 2013 CFR

...stearate. (a) Calcium stearate (Ca(C17 H35 COO)2 , CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as a white precipitate by mixing calcium chloride and sodium stearate...

2013-04-01

364

A comparative study of antioxidative activity of calcium-D-glucarate, sodium-D-gluconate and D-glucono-1,4-lactone in a human blood platelet model.  

PubMed

D-glucono-1,4-lactone, sodium D-gluconate and calcium D-glucarate are non-toxic glucose derivatives occurring naturally in fruits and vegetables. Calcium D-glucarate is promoted as an orally bioavailability dietary supplement with potential chemopreventive activity without adverse effects. Despite many commercial applications in pharmaceutical and food industries the potential activity mechanisms of glucarate and gluconate are not clear. The purpose of this study was to investigate and compare the effects of these compounds on blood platelets under oxidative stress conditions and to examine their role in thrombin-induced platelet activation. Platelet activation is essential in haemostasis, tumor progression and allergic and non-allergic inflammation, where reactive oxygen species are involved. The antiplatelet and antioxidative activity was studied in vitro by measuring levels of specific oxidative stress markers: thiobarbituric acid reactive substances, superoxide anion, carbonyl groups, 3-nitrotyrosine, protein and low molecular weight thiols. All tested compounds significantly inhibited thrombin-induced arachidonic peroxidation, O??? production and also platelet protein oxidation/nitration induced by peroxynitrite, which is a strong oxidant formed intravascularly in vivo. Carbonyl group generation, thiol oxidation and nitrotyrosine formation were significantly decreased in the presence of glucose derivatives. The obtained results demonstrate that tested compounds may be helpful in the prevention of excessive platelet activation through the antioxidant mechanisms. Comparative studies indicate the predominant preventive activity of sodium D-gluconate. In general, the consumption of apples or apple juice as well as oranges, grapefruit and cruciferous vegetables, sources of large amounts of tested derivatives, have beneficial effects on platelets under oxidative stress. PMID:20873960

Saluk-Juszczak, Joanna

2010-01-01

365

The Effect of Sodium Chloride on the Corrosion of Concrete Reinforcing Steel and on the pH of Calcium Hydroxide Solution.  

National Technical Information Service (NTIS)

The electrical half-cell potential measurement is a valid technique for detecting the existence of corrosion in the steel reinforcement of chloride-containing concrete. The voltage which it measures is not directly affected by the presence of sodium chlor...

H. A. Berman

1974-01-01

366

Biliary calcium and bile acid secretion in intact and TPTX rats with varying plasma calcium concentration  

Microsoft Academic Search

Investigations of the effects of plasma calcium concentration on the relationship between biliary secretion of bile acid and calcium were performed in normocalcemic, calcium gluconate-induced hypercalcemie, thyroparathyroidectomy-induced hypocalcemic (TPTX) rats, and TPTX rats that received calcium gluconate to maintain normocalcemia. Studies were done at normal bile flow and at sodium taurocholate-stimulated bile flow. The results showed that biliary calcium secretion,

L. Limlomwongse; C. Deachapunya; N. Krishnamra

1988-01-01

367

General trends in the desolvation behavior of calcium salts and the characterization of mesomorphous calcium salts  

Microsoft Academic Search

The general objective of this project is to characterize, investigate and understand the physical and chemical properties of liquid crystals obtained from hydrated calcium salts upon dehydration. This work will also test the hypothesis that mesomorphous calcium salts are liquid crystals with intermediate physical and chemical properties between the corresponding crystalline and amorphous phases.^ The work described in this thesis

Faraj Atassi

2007-01-01

368

Thermodynamic modelling of the hydration of Portland cement  

SciTech Connect

A thermodynamic model is developed and applied to calculate the composition of the pore solution and the hydrate assemblage during the hydration of an OPC. The calculated hydration rates of the individual clinker phases are used as time dependent input. The modelled data compare well with the measured composition of pore solutions gained from OPC as well as with TGA and semi-quantitative XRD data. The thermodynamic calculations indicate that in the presence of small amounts of calcite typically included in OPC cements, C-S-H, portlandite, ettringite and calcium monocarbonates are the main hydration products. The thermodynamic model presented in this paper helps to understand the interactions between the different components and the environment and to predict the influence of changes in cement composition on the hydrate assemblage.

Lothenbach, Barbara [Empa, Laboratory for Concrete and Construction Chemistry, Uberlandstrasse 129, 8600 Duebendorf (Switzerland)]. E-mail: barbara.lothenbach@empa.ch; Winnefeld, Frank [Empa, Laboratory for Concrete and Construction Chemistry, Uberlandstrasse 129, 8600 Duebendorf (Switzerland)

2006-02-15

369

Modeling and simulation of cement hydration kinetics and microstructure development  

SciTech Connect

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.

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

370

Gas hydrate and humans  

USGS Publications Warehouse

The potential effects of naturally occurring gas hydrate on humans are not understood with certainty, but enough information has been acquired over the past 30 years to make preliminary assessments possible. Three major issues are gas hydrate as (1) a potential energy resource, (2) a factor in global climate change, and (3) a submarine geohazard. The methane content is estimated to be between 1015 to 1017 m3 at STP and the worldwide distribution in outer continental margins of oceans and in polar regions are significant features of gas hydrate. However, its immediate development as an energy resource is not likely because there are various geological constraints and difficult technological problems that must be solved before economic recovery of methane from hydrate can be achieved. The role of gas hydrate in global climate change is uncertain. For hydrate methane to be an effective greenhouse gas, it must reach the atmosphere. Yet there are many obstacles to the transfer of methane from hydrate to the atmosphere. Rates of gas hydrate dissociation and the integrated rates of release and destruction of the methane in the geo/hydro/atmosphere are not adequately understood. Gas hydrate as a submarine geohazard, however, is of immediate and increasing importance to humans as our industrial society moves to exploit seabed resources at ever-greater depths in the waters of our coastal oceans. Human activities and installations in regions of gas-hydrate occurrence must take into account the presence of gas hydrate and deal with the consequences of its presence.

Kvenvolden, K. A.

2000-01-01

371

Phase transitions in biogenic amorphous calcium carbonate  

NASA Astrophysics Data System (ADS)

Geological calcium carbonate exists in both crystalline phases and amorphous phases. Compared with crystalline calcium carbonate, such as calcite, aragonite and vaterite, the amorphous calcium carbonate (ACC) is unstable. Unlike geological calcium carbonate crystals, crystalline sea urchin spicules (99.9 wt % calcium carbonate and 0.1 wt % proteins) do not present facets. To explain this property, crystal formation via amorphous precursors was proposed in theory. And previous research reported experimental evidence of ACC on the surface of forming sea urchin spicules. By using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), we studied cross-sections of fresh sea urchin spicules at different stages (36h, 48h and 72h after fertilization) and observed the transition sequence of three mineral phases: hydrated ACC ? dehydrated ACC ? biogenic calcite. In addition, we unexpectedly found hydrated ACC nanoparticles that are surrounded by biogenic calcite. This observation indicates the dehydration from hydrated ACC to dehydrated ACC is inhibited, resulting in stabilization of hydrated ACC nanoparticles. We thought that the dehydration was inhibited by protein matrix components occluded within the biomineral, and we designed an in vitro assay to test the hypothesis. By utilizing XANES-PEEM, we found that SM50, the most abundant occluded matrix protein in sea urchin spicules, has the function to stabilize hydrated ACC in vitro.

Gong, Yutao

372

Evolution of iron speciation during hydration of C4AF.  

PubMed

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 C4AF 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 C4AF 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 C4AF 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 C4AF forms C3AH6 (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 C3AH6; iron does not seem to be incorporated in the AFm structure. PMID:16697177

Rose, J; Bnard, A; El Mrabet, S; Masion, A; Moulin, I; Briois, V; Olivi, L; Bottero, J-Y

2006-01-01

373

Combustion of Methane Hydrate  

NASA Astrophysics Data System (ADS)

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

Roshandell, Melika

374

Hydration Properties of Soybean Protein Isolates  

Microsoft Academic Search

Hydration properties of soybean isolates with different processing conditions (heat treatments, pH and protein concentrations) were studied. Degree of denaturation,, solubility in water, in 0.2mol\\/L NaCl, and in media of different sodium dodecyl sulfate concentrations, viscosity and water imbibing capacity of the different samples were determinated and correlated. Treatments at temperatures higher than 80C denatured 11S and 7S proteins, leading

Gabriel Remondetto; Maria Cristina Aon; Rolando Jose Gonzlez

2001-01-01

375

The growth rate of gas hydrate from refrigerant R12  

SciTech Connect

Experimental and theoretical investigations were presented dealing with three phase direct-contact heat transfer by evaporation of refrigerant drops in an immiscible liquid. Refrigerant R12 was used as the dispersed phase, while water and brine were the immiscible continuous phase. A numerical solution is presented to predict the formation rate of gas hydrates in test column. The solution provided an acceptable agreement when compared with experimental results. The gas hydrate growth rate increased with time. It increased with increasing dispersed phase flow rate. The presence of surface-active sodium chloride in water had a strong inhibiting effect on the gas hydrate formation rate. (author)

Kendoush, Abdullah Abbas; Jassim, Najim Abid [Centre of Engineering Physics, Ministry of Sciences and Technology, P.O. Box 765, Baghdad (Iraq); Joudi, Khalid A. [Al-Nahrain University, Baghdad (Iraq)

2006-07-15

376

Fluoride coatings make effective lubricants in molten sodium environment  

NASA Technical Reports Server (NTRS)

Coating bearing surfaces with calcium fluoride-barium fluoride film provides effective lubrication against sliding friction in molten sodium and other severe environments at high and low temperatures.

1966-01-01

377

Methane Hydrate Field Program  

SciTech Connect

This final report document summarizes the activities undertaken and the output from three primary deliverables generated during this project. This fifteen month effort comprised numerous key steps including the creation of an international methane hydrate science team, determining and reporting the current state of marine methane hydrate research, convening an international workshop to collect the ideas needed to write a comprehensive Marine Methane Hydrate Field Research Plan and the development and publication of that plan. The following documents represent the primary deliverables of this project and are discussed in summary level detail in this final report. Historical Methane Hydrate Project Review Report Methane Hydrate Workshop Report Topical Report: Marine Methane Hydrate Field Research Plan Final Scientific/Technical Report

None

2013-12-31

378

NaI(Tl) camera crystals: imaging capabilities of hydrated regions on the crystal surface  

Microsoft Academic Search

Sodium iodide (NaI(Tl)) camera crystals may become hydrated. Hydration results in small spots on the crystal surface that at first are white but later turn yellowish. The appearance of these spots--as any artifact--in a diagnostic image is to be avoided, and the crystal should be replaced. The image of the hydrated spots of an aged NaI(Tl) camera crystal has been

Keszthelyi-Landori

1986-01-01

379

Experiments on fast nucleation and growth of HCFC141b gas hydrate in static water columns  

Microsoft Academic Search

A major technical issue in the realization of refrigerants gas hydrates energy storage systems is to develop a practical means for rapid hydrate formation. In this paper, the nucleation and growth processes of HCFC141b (CH3CCl2F, HCFC141b) gas hydrate in a column of water added with 0.038wt% sodium dodecylbenzenesulfonate-6 and with a metal rod which was placed in the center of

Jinping Li; Kaihua Guo; Deqing Liang; Ruzhu Wang

2004-01-01

380

Estimation of ultra-stability of methane hydrate at 1 atm by thermal conductivity measurement  

Microsoft Academic Search

Thermal conductivity of methane hydrate was measured in hydrate dissociation self-preservation zone by means of the transient plane source (TPS) technique developed by Gustafsson. The sample was formed from 99.9% (volume ratio) methane gas with 280 ppm sodium dodecyl sulfate (SDS) solution under 6.6 MPa and 273.15 K. The methane hydrate sample was taken out of the cell and moved

Dongliang Li; Deqing Liang; Shuanshi Fan; Hao Peng

2010-01-01

381

The specific surface area of methane hydrate formed in different conditions and manners  

Microsoft Academic Search

The specific surface area of methane hydrates, formed both in the presence and absence of sodium dodecyl sulfate (SDS) and\\u000a processed in different manners (stirring, compacting, holding the hydrates at the formation conditions for different periods\\u000a of time, cooling the hydrates for different periods of time before depressurizing them), was measured under atmospheric pressure\\u000a and temperatures below ice point. It

XiuLin Wang; ChangYu Sun; GuangJin Chen; LanYing Yang; QingLan Ma; Jun Chen; XuLong Tang; Peng Liu

2009-01-01

382

Does SDS micellize under methane hydrate-forming conditions below the normal Krafft point?  

Microsoft Academic Search

Sodium dodecyl sulfate (SDS) can accelerate nucleation and growth of gas hydrates in a quiescent system. The objective of this paper is to investigate whether or not SDS micelles form in the meta-stable region of methane hydrates by the direct measurement of aqueous SDS concentration. The SDS solubility in water with high-pressure methane is identical to that under atmospheric pressure

J. S. Zhang; S. Lee; Jae W. Lee

2007-01-01

383

Microstructure development in mixes of calcium aluminate cement with silica fume or fly ash  

Microsoft Academic Search

The most widely identified degradation process suffered by calcium aluminate cement (CAC) is the so-called conversion of hexagonal\\u000a calcium aluminate hydrate to cubic form. This conversion is usually followed by an increase in porosity determined by the\\u000a different densities of these hydrates and the subsequent loss of strength. Mixes of calcium aluminate cement (CAC) and silica\\u000a fume (SF) or fly

Ana Hidalgo; J. L. Garca; Ma. Cruz Alonso; L. Fernndez; Carmen Andrade

2009-01-01

384

Sodium (Salt or Sodium Chloride)  

MedlinePLUS

... Fit-Friendly Worksites Program Requirements Fit-Friendly Resources Sodium and Salt Updated:Jun 23,2014 About Sodium Frequently Asked ... Dining Out Cookbooks and Health Guides Reduce Your Sodium Intake Receive Healthy Living news every month! First ...

385

Combustion synthesis of calcium aluminates  

SciTech Connect

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. The present work discusses a straightforward combustion synthesis technique to prepare submicron calcium aluminates using the corresponding metal nitrates-urea mixtures, at low temperature and short reaction times. The effect of the ratio oxidizer/fuel in the redox mixture was investigated, namely, to find out if urea contents below stoichiometry were enough to trigger the explosive combustion of the fuel and the subsequent decomposition of the salts, and how that ratio affected the phase formation and the characteristics, e.g., morphology and grain size, of the powder produced.

Fumo, D.A.; Segadaes, A.M. [Univ. of Aveiro (Portugal). Dept. Ceramics and Glass Engineering] [Univ. of Aveiro (Portugal). Dept. Ceramics and Glass Engineering; Morelli, M.R. [Federal Univ. Sao Carlos, Sao Paulo (Brazil). Dept. of Materials Engineering] [Federal Univ. Sao Carlos, Sao Paulo (Brazil). Dept. of Materials Engineering

1996-10-01

386

Gas hydrate measurements at Hydrate Ridge using Raman spectroscopy  

Microsoft Academic Search

Oceanic gas hydrates have been measured near the seafloor for the first time using a seagoing Raman spectrometer at Hydrate Ridge, Oregon, where extensive layers of hydrates have been found to occur near the seafloor. All of the hydrates analyzed were liberated from the upper meter of the sediment column near active gas venting sites in water depths of 770780m.

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

2007-01-01

387

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

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 5C 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.

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

2013-01-01

388

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

PubMed

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

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

2005-03-01

389

Inotropic effects and changes in sodium and calcium contents associated with inhibition of monovalent cation active transport by ouabain in cultured myocardial cells  

PubMed Central

Cultured monolayers of spontaneously contracting chick embryo ventricular cells were perfused with culture medium containing ouabain. Contractile state was monitored by an optical-video system recording amplitude and velocity of cell wall motion. Positive inotropic effects of 2.5 x 10(-7) to 10(-6) M ouabain were manifest within 1.5-2 min, and reached a stable plateau within 5-6 min. The inotropic effect was fully reversed within 5 min after washout of ouabain. Inhibition of uptake of 42K+ (or the K+ analog 86Rb+) and efflux of 24Na+ occurred 1.5-2 min after exposure to ouabain. The degree of inhibition of transport was closely related to the magnitude of the positive inotropic effect throughout the ouabain concentration range 10(-7) to 10(-6) M. After washout of ouabain from monolayers, the monovalent cation active transport rate returned to normal within 1 min. Thus, both the onset and offset of inotropic action of ouabain were closely related temporally to inhibition of the sodium pump. Exposure to ouabain caused significant increases in exchangeable Na and Ca contents that appeared to be developed within 5 min. These data support the hypothesis that inhibition of monovalent cation active transport by ouabain is causally related to the development of positive inotropy and are consistent with modulation of Ca content by intracellular Na+ via the Na+-Ca2+ exchange carrier mechanism.

1979-01-01

390

Ultrafine calcium aerosol: Generation and use of a sorbent for sulfur in coal combustion. Volume 2, Economics: Final report, August 1, 1988--October 31, 1991  

SciTech Connect

The goal of this study is to determine the cost effectiveness of using calcium-hydroxide powder sorbent in a commercial power plant flue gas desulfurization (FGD) application. The cost analysis methodology found herein is a direct application of the one found in the January 1986 report, ``Economic Evaluation of Dry-Injection Flue Gas Desulfurization Technology by the Electric Power Research Institute (EPRI). The EPRI study addresses the economic issue of installing a dry-injection FGD system on a 1000 MW (2-500 MW units) power plant using sodium-rich powder sorbents derived from nahcolite and trona ores. In this report`s treatment, the calcium-based derivatives of hydrated limestone are compared directly to nahcolite and trona for both low and high sulfur coals. This type of evaluation is allowable due to the similar material handling properties of 1/4 inch hydrated limestone in comparison to those properties for nahcolite and trona. Thus, this report repeats the EPRI cost analysis for a slightly modified limestone-based FGD design. Note that the calculation methodology is not discussed, in this report as it has already been outlined in the EPRI study. Instead, Appendices A and B contain copies of the calculation spreadsheets based on the EPRI method for the hydrated limestone system.

Alam, M.K.; Nahar, N.U.; Stewart, G.D.; Prudich, M.E. [comps.] [Ohio Coal Research Center, Athens, OH (United States)

1991-11-01

391

The efflux of potassium, sodium, chloride, calcium and sulphate ions and of sorbitol and glycerol during the cardiac cycle in frog's ventricle  

PubMed Central

1. The exchanges of potassium and various other substances have been measured in beating frog's ventricles, using both superfused and distended preparations. In both preparations the high fluid flow rates used (1 ml./sec) cleared the ventricular cavity with a half-time (T) of about 130 msec. 2. Histological sections show that the modal strand radius in the relaxed or contracted distended ventricle is 175 ?, and in the relaxed and contracted superfused ventricle is 175 and 275 ? respectively. 3. In quiescent ventricles the resting potassium influx and efflux are approximately equal at about 16 p-mole/cm2.sec. This figure is computed from Niedergerke's (1963b) estimate of a cell size of 35 ? taken from electron-micrographs. If the older figure of 92 ? from single isolated cells is used (Skramlik, 1921) then the fluxes are about 44 p-mole/cm2.sec. To allow for some cell damage in these preparations a further increase in flux of about 30% may be necessary. 4. Contraction leads to a diminution of both potassium influx and efflux. Measurements made at 100 msec intervals throughout the cardiac cycle have demonstrated (a) that this decreased K efflux occurs at the same time as the mechanical twitch, and (b) that the size of the decrease is dependent on the external calcium concentration. Other experiments show that a similar decrease can be obtained by inducing a contracture at a constant membrane potential. It is concluded that the decreased K efflux during contraction is due to mechanical distortion of the tissue. This leads to a further slowing of the K diffusion and allows considerable reabsorption of K to occur into the cells. 5. Efflux analysis suggests that normal K diffusion in the extracellular space may be about 1/10 of that in free solution. If this is correct the true membrane fluxes may be 5 those measured. 6. Phasic efflux measurements of Na, Ca, K, Cl, SO4, sorbitol and erythritol show that a peak of efflux occurs just after the point of maximum rate of contraction of the ventricle. The peak efflux of K is least but all the other substances show similar patterns. In calcium-free solutions these phasic changes are absent. It is concluded that these effects are mechanical. 7. Net K and Na changes were measured in ventricles poisoned by ouabain. The computed net changes for quiescent ventricles were a gain of 28 p-mole/cm2.sec of Na and a loss of 53 p-mole/cm2.sec of K. On stimulation a further increase in Na uptake of 8 p-mole/cm2 occurred with no further loss of potassium. These results are computed for a cell diameter of 35 ?, for the larger diameter of 92 ? appropriate values of Na and K are 74 and 134 p-mole/cm2.sec respectively for quiescent ventricles and an extra Na uptake of 21 p-mole/cm2 per action potential. These results: (a) show that no large degree of single-file interaction occurs on the K movements, (b) are in agreement with the hypothesis that the membrane K fluxes are underestimated and (c) show that sufficient Na enters the cells per action potential to discharge a capacity of about 4 ?F/cm2. 8. A general conclusion reached in these experiments is that ion movements during the long cardiac action potential cannot easily be measured because of mechanical artifacts.

Lamb, J. F.; McGuigan, J. A. S.

1968-01-01

392

Molecular silicate and aluminate species in anhydrous and hydrated cements.  

PubMed

The compositions and molecular structures of anhydrous and hydrated cements are established by using advanced solid-state nuclear magnetic resonance (NMR) spectroscopy methods to distinguish among different molecular species and changes that occur as a result of cement hydration and setting. One- and two-dimensional (2D) solid-state (29)Si and (27)Al magic-angle spinning NMR methodologies, including T(1)-relaxation-time- and chemical-shift-anisotropy-filtered measurements and the use of very high magnetic fields (19 T), allow resonances from different silicate and aluminate moieties to be resolved and assigned in complicated spectra. Single-pulse (29)Si and (27)Al NMR spectra are correlated with X-ray fluorescence results to quantify the different crystalline and disordered silicate and aluminate species in anhydrous and hydrated cements. 2D (29)Si{(1)H} and (27)Al{(1)H} heteronuclear correlation NMR spectra of hydrated cements establish interactions between water and hydroxyl moieties with distinct (27)Al and (29)Si species. The use of a (29)Si T(1)-filter allows anhydrous and hydrated silicate species associated with iron-containing components in the cements to be distinguished, showing that they segregate from calcium silicate and aluminate components during hydration. The different compositions of white Portland and gray oilwell cements are shown to have distinct molecular characteristics that are correlated with their hydration behaviors. PMID:20455533

Rawal, Aditya; Smith, Benjamin J; Athens, George L; Edwards, Christopher L; Roberts, Lawrence; Gupta, Vijay; Chmelka, Bradley F

2010-06-01

393

Adsorption of Gemini surfactants onto clathrate hydrates.  

PubMed

This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface. PMID:24144366

Salako, O; Lo, C; Couzis, A; Somasundaran, P; Lee, J W

2013-12-15

394

Hydrated silicas modified by nonsilane pro-adhesion compounds  

Microsoft Academic Search

The surface modification of hydrated silicas, precipitated from a solution of sodium metasilicate and gaseous carbon dioxide, was carried out. The modification was conducted in three ways (modification with evaporation of the solvent, heating of the silica-modifying compound solution system in a reflux condenser, and surface modification in a vacuum evaporator), using various amounts of pro-adhesion compounds, dissolved in organic

Andrzej Krysztafkiewicz; Bozena Rager

1999-01-01

395

Hydrate adhesive and tensile strengths  

NASA Astrophysics Data System (ADS)

The physical properties of hydrate-bearing sediments depend on the interaction between hydrates and minerals. In particular, hydrates prefer to nucleate on mineral surfaces, therefore, the hydrate-mineral adhesive strength and the tensile strength of the hydrate mass itself affect the mechanical response of hydrate-bearing sediments. In this study, ice and hydrates made with various guest molecules (CO2, CH4, and THF) are formed between mica and calcite substrates. Adhesive and tensile strengths are measured by applying an external pull-out force. Results show that tensile failure occurs in CO2 and CH4 hydrates when calcite is the substrate, while ice and all hydrates exhibit adhesive failure on mica. The debonding strength is higher when calcite substrates are involved rather than mica substrates. A nominal pull-out strength of 0.15 0.03 MPa can be adopted for mechanical analyses of hydrate-bearing sediments.

Jung, J. W.; Santamarina, J. Carlos

2011-08-01

396

Hydrothermal formation of the calcium silicate hydrates, tobermorite (Ca 5Si 6O 16(OH) 24H 2O) and xonotlite (Ca 6Si 6O 17(OH) 2): an in situ synchrotron study  

Microsoft Academic Search

In situ energy-dispersive X-ray diffraction (XRD) techniques have been employed to study the hydrothermal formation of crystalline tobermorite and xonotlite. Alkoxide gels of tobermorite composition with varying aluminium contents (Al\\/(Al+Si)=0 to 0.15) were reacted with a saturated calcium hydroxide solution at temperatures varying from 190C to 310C on the saturated vapour pressure curve. Reaction products consisted of tobermorite, xonotlite or

S Shaw; S. M Clark; C. M. B Henderson

2000-01-01

397

Hydrate morphology: Physical properties of sands with patchy hydrate saturation  

USGS Publications Warehouse

The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

Dai, S.; Santamarina, J. C.; Waite, William F.; Kneafsey, T. J.

2012-01-01

398

Hydrate morphology: Physical properties of sands with patchy hydrate saturation  

NASA Astrophysics Data System (ADS)

The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

Dai, S.; Santamarina, J. C.; Waite, W. F.; Kneafsey, T. J.

2012-11-01

399

Effect of sodium, potassium, magnesium, and calcium salt cations on pH, proteolysis, organic acids, and microbial populations during storage of full-fat Cheddar cheese.  

PubMed

Sodium reduction in cheese can assist in reducing overall dietary Na intake, yet saltiness is an important aspect of cheese flavor. Our objective was to evaluate the effect of partial substitution of Na with K on survival of lactic acid bacteria (LAB) and nonstarter LAB (NSLAB), pH, organic acid production, and extent of proteolysis as water-soluble nitrogen (WSN) and protein profiles using urea-PAGE, in Cheddar cheese during 9mo of storage. Seven Cheddar cheeses with molar salt contents equivalent to 1.7% salt but with different ratios of Na, K, Ca, and Mg cations were manufactured as well as a low-salt cheese with 0.7% salt. The 1.7% salt cheeses had a mean composition of 352g of moisture/kg, 259g of protein/kg and 50% fat-on-dry-basis, and 17.5g of salt/kg (measured as Cl(-)). After salting, a faster initial decrease in cheese pH occurred with low salt or K substitution and it remained lower throughout storage. No difference in intact casein levels or percentage WSN levels between the various cheeses was observed, with the percentage WSN increasing from 5% at d 1 to 25% at 9mo. A greater decrease in intact ?s1-casein than ?-casein was detected, and the ratio of ?s1-casein (f121-199) to ?s1-casein could be used as an index of ripening. Typical changes in bacteria microflora occurred during storage, with lactococci decreasing gradually and NSLAB increasing. Lowering the Na content, even with K replacement, extended the crossover time when NSLAB became dominant. The crossover time was 4.5mo for the control cheese and was delayed to 5.2, 6.0, 6.1, and 6.2mo for cheeses with 10, 25, 50, and 75% K substitution. Including 10% Mg or Ca, along with 40% K, further increased crossover time, whereas the longest crossover time (7.3mo) was for low-salt cheese. By 9mo, NSLAB levels in all cheeses had increased from initial levels of ?10(2) to approximately 10(6)cfu/g. Lactococci remained at 10(6) cfu/g in the low-salt cheese even after 9mo of storage. The propionic acid concentration in the cheese increased when NSLAB numbers were high. Few other trends in organic acid concentration were observed as a function of Na content. PMID:24913647

McMahon, D J; Oberg, C J; Drake, M A; Farkye, N; Moyes, L V; Arnold, M R; Ganesan, B; Steele, J; Broadbent, J R

2014-08-01

400

Investigation on MSW fly ash treatment by reactive calcium aluminates and phases formed  

Microsoft Academic Search

In this study hydration reactions of MSW fly ash with an experimental C12A7 \\/ C3A -cement are investigated. The fly ash has high contents of soluble calcium sulphates, alkali chlorides and heavy metals. During the first hours the calcium aluminates react with the calcium sulphate to form ettringite. On condition that the amount of added cement is sufficient, after complete

S. Auer; H.-J. Kuzel; H. Pllmann; F. Sorrentino

1995-01-01

401

Physical properties and self-setting mechanism of calcium phosphate cements from calcium bis-dihydrogenophosphate monohydrate and calcium oxide  

Microsoft Academic Search

An apatitic calcium phosphate cement was developed from calcium bis-dihydro-genophosphate monohydrate (or monocalcium phosphate monohydrate, MCPM) and calcium oxide (CaO). The powder had a Ca\\/P molar ratio of 1.67, and the liquid was either pure water or 0.25 M1 M sodium phosphate buffer, pH 7.4. The influence of the powder-to-liquid (P\\/L) ratio on the setting time and the mechanical strength

P. BOUDEVILLE; S. SERRAJ; J.-M. LELOUP; J. MARGERIT; B. PAUVERT; A. TEROL

1999-01-01

402

HYDRATE CORE DRILLING TESTS  

Microsoft Academic Search

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

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

2002-01-01

403

Vocal Fold Surface Hydration: A review  

PubMed Central

Vocal fold surface liquid homeostasis contributes to optimal vocal physiology. In this paper we review emerging evidence that vocal fold surface liquid is maintained in part by salt and water fluxes across the epithelium. Based on recent immunolocalization and electrophysiological findings, we describe a transcellular pathway as one mechanism for regulating superficial vocal fold hydration. We propose that the pathway includes the sodium-potassium pump, sodium-potassium-chloride cotransporter, epithelial sodium channels, cystic fibrosis transmembrane regulator chloride channels, and aquaporin water channels. By integrating knowledge of the regulating mechanisms underlying ion and fluid transport with observations from hydration challenges and treatments using in vitro and in vivo studies, we provide a theoretical basis for understanding how environmental and behavioral challenges and clinical interventions may modify vocal fold surface liquid composition. We present converging evidence that clinical protocols directed at facilitating vocal fold epithelial ion and fluid transport may benefit healthy speakers, those with voice disorders, and those at risk for voice disorders.

Leydon, Ciara; Sivasankar, Mahalakshmi; Falciglia, Danielle Lodewyck; Atkins, Christopher; Fisher, Kimberly V.

2009-01-01

404

Calcium measurements with electron probe X-ray and electron energy loss analysis.  

PubMed

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry, and various analytical modes such as static probing and X-ray imaging. Some common artifacts are beam damage and contamination. Inherent pitfalls of energy dispersive X-ray systems include Si escape peaks, doublets, background, and detector calibration shifts. Quantitative calcium analysis of thin cryosections is carried out in real time using a multiple least squares fitting program on filtered X-ray spectra and normalizing the calcium peak to a portion of the continuum. Recent work includes the development of an X-ray imaging system where quantitative data can be retrieved off-line. The minimum detectable concentration of calcium in biological cryosections is approximately 300 mumole kg dry weight with a spatial resolution of approximately 100 A. The application of electron energy loss (EELS) techniques to the detection of calcium offers the potential for greater sensitivity and spatial resolution in measurement and imaging. Determination of mass thickness with EELS can facilitate accurate calculation of wet weight concentrations from frozen hydrated and freeze-dried specimens. Calcium has multiple effects on cell metabolism, membrane transport and permeability and, thus, on overall cell physiology or pathophysiology. Cells can be rapidly frozen for EPXMA during basal or altered functional conditions to delineate the location and amount of calcium within cells and the changes in location and concentration of cations or anions accompanying calcium redistribution. Recent experiments in our laboratory document that EPXMA in combination with other biochemical and electrophysiological techniques can be used to study, for example, sodium and calcium compartmentation in cultured cardiac cells. Such analyses can also be used to clarify the role of calcium in anoxic renal cell injury and to evaluate proposed ionic defects in cells of individuals with cystic fibrosis. PMID:2190819

LeFurgey, A; Ingram, P

1990-03-01

405

Calcium measurements with electron probe X-ray and electron energy loss analysis.  

PubMed Central

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry, and various analytical modes such as static probing and X-ray imaging. Some common artifacts are beam damage and contamination. Inherent pitfalls of energy dispersive X-ray systems include Si escape peaks, doublets, background, and detector calibration shifts. Quantitative calcium analysis of thin cryosections is carried out in real time using a multiple least squares fitting program on filtered X-ray spectra and normalizing the calcium peak to a portion of the continuum. Recent work includes the development of an X-ray imaging system where quantitative data can be retrieved off-line. The minimum detectable concentration of calcium in biological cryosections is approximately 300 mumole kg dry weight with a spatial resolution of approximately 100 A. The application of electron energy loss (EELS) techniques to the detection of calcium offers the potential for greater sensitivity and spatial resolution in measurement and imaging. Determination of mass thickness with EELS can facilitate accurate calculation of wet weight concentrations from frozen hydrated and freeze-dried specimens. Calcium has multiple effects on cell metabolism, membrane transport and permeability and, thus, on overall cell physiology or pathophysiology. Cells can be rapidly frozen for EPXMA during basal or altered functional conditions to delineate the location and amount of calcium within cells and the changes in location and concentration of cations or anions accompanying calcium redistribution. Recent experiments in our laboratory document that EPXMA in combination with other biochemical and electrophysiological techniques can be used to study, for example, sodium and calcium compartmentation in cultured cardiac cells. Such analyses can also be used to clarify the role of calcium in anoxic renal cell injury and to evaluate proposed ionic defects in cells of individuals with cystic fibrosis.

LeFurgey, A; Ingram, P

1990-01-01

406

Calcium - urine  

MedlinePLUS

... from the kidneys, which causes calcium kidney stones Sarcoidosis Takiong too much calcium Too much production of ... metabolism. In: Goldman L, Ausiello D, eds. Cecil Medicine . 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap ...

407

Natriuretic and aquaretic effects of intravenously infused calcium in preascitic human cirrhosis: physiopathological and clinical implications  

Microsoft Academic Search

Background: Preascitic cirrhosis is characterised by subtle renal sodium retention. Calcium inhibits Na+K+2Cl? cotransport in the Henles loop and could potentially correct sodium-handling abnormalities at that site.Aim: To investigate the effects of calcium infusion on sodium handling in 10 patients with preascitic cirrhosis and nine healthy controls after 1 week of sodium loading of 200 mmol sodium\\/day.Methods: All patients underwent

G Sansoe?; F Wong

2007-01-01

408

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

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.

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

1986-10-09

409

Calcium tartrate gel.  

PubMed

A method for preparation of a gel for chromatography has been developed. The adsorbent is calcium tartrate treated with potassium phosphate. By changing the temperature of synthesis (10-65 degrees C) and concentration of the salts (calcium chloride and sodium potassium tartrate) from 0.3 to 3.0 M, we have been able to prepare adsorbent crystals of definite sizes in the range 35-200 microns. In all cases, for synthesis of adsorbent, the Ca2+/K+Na+ ratio was greater than 1. After treatment of calcium tartrate crystals with 0.075-1.5 M potassium phosphate at 80-100 degrees C and pH 8.5-9.0, an appropriate chromatographic adsorbent was prepared. The chromatographic properties of calcium tartrate gel have been studied. The adsorbent permits flow rates of 25-150 ml/h, depending on the particle size. The capacity of calcium tartrate gel for binding BSA, RNA, and DNA was similar to that of Tiselius' hydroxyapatite (A. Tiselius, S. Hjerten, O. Levin (1956) Arch. Biochem. Biophys. 65, 132-155). The spheric shape of gel particles permits uniform and compact packing of adsorbent under the conditions of column chromatography. PMID:2757203

Akhrem, A A; Drozhdenyuk, A P

1989-05-15

410

Comparison of amorphous TCP nanoparticles to micron-sized alpha-TCP as starting materials for calcium phosphate cements.  

PubMed

The development of degradable bone cements with a mineral composition similar to natural bone was investigated using highly reactive calcium phosphate phases as starting materials. Mixtures of XRD-amorphous, glassy tricalcium phosphate (amorphous-TCP) nanoparticles of 25-60 nm size and micron sized, milled alpha-TCP were set by hydration with sodium phosphate buffer and investigated for possible application as single component calcium phosphate cements (CPCs). Isothermal calorimetry allowed a precise tracking of the setting process. Amorphous-TCP nanoparticles converted into calcium deficient hydroxyapatite with cement setting times below 12 min. The total energy release by the material during hardening corroborated the importance of high specific surface area and phase composition, that is, amorphous state of the nanometric starting material as repeatedly suggested earlier. The phase composition of the resulting CPCs was characterized by X-ray diffraction before and after setting. The morphology was investigated by nitrogen adsorption, scanning, and transmission electron microscopy and revealed the formation of highly porous calcium deficient hydroxyapatite with specific surface areas of up to 160 m(2) g(-1) after setting. In contrast to the very fast reaction time and highest specific surface area, the mechanical stability of the resulting CPC is still insufficient and requires further improvement. PMID:17410573

Brunner, Tobias J; Bohner, Marc; Dora, Claudio; Gerber, Christian; Stark, Wendelin J

2007-11-01

411

Hydrothermal Transformation of the Calcium Aluminum Oxide Hydrates CaAl2O4 . 10H2O and Ca2Al2O. 8H2O to Ca3Al2(OH)12 Investigated by In Situ Synchrotron X-ray Powder Diffraction  

SciTech Connect

The hydrothermal transformation of calcium aluminate hydrates were investigated by in situ synchrotron X-ray powder diffraction in the temperature range 25 to 170 C. This technique allowed the study of the detailed reaction mechanism and identification of intermediate phases. The material CaAl{sub 2}O{sub 4}{center_dot}10H{sub 2}O converted to Ca{sub 3}Al{sub 2}(OH){sub 12} and amorphous aluminum hydroxide. Ca{sub 2}Al{sub 2}O{sub 5}{center_dot}8H{sub 2}O transformed via the intermediate phase Ca{sub 4}Al{sub 2}O{sub 7}{center_dot}13H{sub 2}O to Ca{sub 3}Al{sub 2}(OH){sub 12} and gibbsite, Al(OH){sub 3}. The phase Ca{sub 4}Al{sub 2}O{sub 7}{center_dot}19H{sub 2}O reacted via the same intermediate phase to Ca{sub 3}Al{sub 2}(OH){sub 12} and mainly amorphous aluminum hydroxide. The powder pattern of the intermediate phase is reported.

Jensen,T.; Christensen, A.; Hanson, J.

2005-01-01

412

The partition coefficients of ethylene between hydrate and vapor for methane + ethylene + water and methane + ethylene + SDS + water systems  

Microsoft Academic Search

The hydrate formation of CH4+C2H4 mixture was studied experimentally in two different cases, with and without the presence of sodium dodecyl sulfate (SDS) in water. The results manifested that the presence of SDS could not only accelerate the hydrate formation process, but also increase the partition coefficient of ethylene between hydrate and vapor drastically. The partition coefficients of ethylene between

L.-W. Zhang; G.-J. Chen; C.-Y. Sun; S.-S. Fan; Y.-M. Ding; X.-L. Wang; L.-Y. Yang

2005-01-01

413

Calcium metabolism and bone calcium content in normal and oophorectomized rats consuming various levels of saline for 12 months.  

PubMed

The effect of different intakes of salt for 12 mo on bone calcium content and urinary excretion of calcium and hydroxyproline were examined in sham operated and oophorectomized (OX) rats to determine the long term effects of high sodium intake and its interaction with estrogen deficiency. Sham operated (n = 24) and OX (n = 24) rats were divided into groups of six rats in a 2 x 4 design. One group of sham and one of OX rats were given 0, 2, 6 or 18 g/L sodium chloride to drink. Urine samples were collected at 0, 2, 4, 6, 10 and 12 mo for the measurement of sodium, calcium, creatinine and hydroxyproline. At the end of 12 mo, blood was taken for measurement of calcium, albumin, alkaline phosphatase and creatinine and the left femur was removed and analyzed for calcium and phosphate. Body weights of the OX rats were higher than the sham operated controls. At the start of the experiment (10 d after OX) urinary excretions of calcium and hydroxyproline were significantly higher in OX rats. However, after 4-6 mo, they were significantly lower in OX rats. Calcium excretion and hydroxyproline excretion were increased by high salt intake, and there was a significant correlation between sodium and calcium excretion (r = 0.962). Bone calcium content of OX rats was lower than their corresponding sham-operated controls. Sodium intake also had a significant effect on bone calcium content. Multiple regression analysis showed that OX and sodium intake explained 7.6% and 1.5% of the variation in bone calcium content. We conclude that high sodium intake causes increased loss of calcium and reduces bone calcium content in sham-operated as well as OX rats. PMID:9482774

Chan, E L; Swaminathan, R

1998-03-01

414

SPECTROGRAPHIC EXAMINATION OF SODIUM NITRITE FOR TRACE IMPURITIES  

Microsoft Academic Search

Development of methods for determining trace amounts of the lighter ; elements in sodium nitrite is described, Aluminums berylliums calciums and ; magnesium are determined by the iron flux procedure after preliminary separation ; from sodium on a cation exchange column. Beryllium, scandiums and titandium are ; similarly determined after separation from sodium by coprecipitation with iron ; hydroxide. Lithium

G. I. Goodfellow; Housley; A. P. S. f Seyfang; T. H. Boyd; M. Diggle

1952-01-01