WorldWideScience

Sample records for calcium sodium silicate

  1. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    Science.gov (United States)

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers Hectorite was nonirritating to the skin of rabbits in a Draize primary skin irritation study. Magnesium Aluminum Silicate and Sodium Magnesium Silicate caused minimal eye irritation in a Draize eye irritation test. Bentonite caused severe iritis after injection into the anterior chamber of the eyes of rabbits and when injected intralamellarly, widespread corneal infiltrates and retrocorneal membranes were recorded. In a primary eye irritation study in rabbits, Hectorite was moderately irritating without washing and practically nonirritating to the eye with a washout. Rats tolerated a single dose of Zeolite A without any adverse reaction in the eye. Calcium Silicate had no discernible effect on nidation or on maternal or fetal survival in rabbits. Magnesium Aluminum Silicate had neither a teratogenic nor adverse effects on the mouse fetus. Female rats receiving a 20% Kaolin diet exhibited maternal anemia but no significant reduction in birth weight of the pups was

  2. The effect of calcium ions and sodium silicate on the adsorption of a model anionic flotation collector on magnetite studied by ATR-FTIR spectroscopy.

    Science.gov (United States)

    Potapova, E; Grahn, M; Holmgren, A; Hedlund, J

    2010-05-01

    Previous studies have shown that agglomeration of the magnetite concentrate after reverse flotation of apatite is negatively affected by the collector species adsorbed on the surface of magnetite. In this work, the effect of ionic strength, calcium ions and sodium silicate on the unwanted adsorption of a model anionic flotation collector on synthetic magnetite was studied in situ using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The amount of collector adsorbed was found to increase with increasing ionic strength at pH 8.5 providing evidence to the contribution of electrostatic forces to the adsorption of the collector. Adding sodium silicate to the system resulted in a threefold decrease in the amount of collector adsorbed compared to when no sodium silicate was added, confirming the depressing activity of sodium silicate on magnetite. Calcium ions were shown to increase the adsorption of both the collector and sodium silicate on magnetite. The depressing effect of sodium silicate on collector adsorption was completely suppressed in the presence of calcium ions under the conditions studied. Furthermore, the amount of collector adsorbed on magnetite from the silicate-collector solution increased 14 times upon addition of calcium ions suggesting that calcium ions in the process water may increase undesired adsorption of the collector on the iron oxide. PMID:20153478

  3. 21 CFR 573.260 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does...

  4. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    International Nuclear Information System (INIS)

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (5(PO4)2SiO4 and Na3Ca6(PO4)5 in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L2,3-edge and calcium (Ca) K-edge XANES. Si L2,3-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L2,3-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and β-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na3Ca6(PO4)5 in a silicate matrix indicating that it is more soluble compared to the other compositions.

  5. MODIFICATION OF PRECIPITATED CALCIUM CARBONATE FILLER USING SODIUM SILICATE/ZINC CHLORIDE BASED MODIFIERS TO IMPROVE ACID-RESISTANCE AND USE OF THE MODIFIED FILLER IN PAPERMAKING

    Directory of Open Access Journals (Sweden)

    Jing Shen

    2009-11-01

    Full Text Available In order to improve the acid-resistant property of papermaking grade precipitated calcium carbonate filler and to obtain modified filler in powder form, sodium silicate/zinc chloride based modifiers were used in filler modification, and the use of modified filler in papermaking of deinked pulp derived from recycled newspaper was also preliminarily investigated. Under the preliminarily optimized experimental conditions, when sodium silicate, zinc chloride, sodium hexametaphosphate, and phosphoric acid with dosages of 10 wt%, 3 wt%, 1 wt% and 0.2 wt%, respectively, were used as modifiers, and when the temperature, aging time, and PCC concentration during the filler modification process was 70 oC, 7 h and 9.1 wt%, respectively, the acid-resistant property of filler was significantly improved after modification, as evaluated using alum consumption and pH methods. The use of modified precipitated calcium carbonate filler prepared under the optimized conditions provided considerably more brightness and light scattering improvement in comparison to unmodified filler, and filler modification was found to have only negligible influence on tensile and burst strength of the paper, air permeability of the paper, and retention performance of the filler. Surface analysis of the modified filler using XPS and SEM confirmed the occurring of surface encapsulation and modification of precipitated calcium carbonate filler when the relevant modifiers were used in filler modification. The encapsulating effect of modifiers on filler was thought to be favorable to improvement in acid-resistant property, and optical properties of the filled paper.

  6. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Graduate Student, Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States); Hu Yongfeng; Zuin, Lucia [Beamline Scientist, Canadian Light Source, Saskatoon, SK (Canada); Appathurai, Narayana [Beamline Scientist, Synchrotron Radiation Center, Madison, WI (United States); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States)

    2011-03-12

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (< 5 wt.%) of Bioglass (registered) 45S5 was added it behaved as a sintering aid and also enhanced the decomposition of hydroxyapatite to {beta}-tricalcium phosphate. However when 10 wt.% and 25 wt.% Bioglass (registered) 45S5 was used it resulted in the formation of Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} and Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L{sub 2,3}-edge and calcium (Ca) K-edge XANES. Si L{sub 2,3}-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L{sub 2,3}-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and {beta}-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in a silicate matrix indicating that it is more soluble compared to the other compositions.

  7. 21 CFR 182.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2227 Calcium silicate. (a) Product. Calcium silicate....

  8. 21 CFR 582.2227 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  9. Tunable luminescence and white light emission of novel multiphase sodium calcium silicate nanophosphors doped with Ce3+, Tb3+, and Mn2+ ions

    International Nuclear Information System (INIS)

    This study reports the sol–gel synthesis of sodium calcium multiphase silicate (SCMS) nanophosphors. X-ray powder diffraction indicated the crystallization of devitrite (Na2Ca3Si6O16), wollastonite-2M (CaSiO3), and cristobalite (SiO2) phases that consistently occurred together upon repeated syntheses. The multiphase silicate system was used as a host matrix for varied concentrations of Ce3+, Tb3+, and Mn2+ dopant ions which resulted in tunable photoluminescence. A broad violet/UV emission band of Ce3+ (350–425 nm) combined with blue-green emissions of Tb3+ (488 and 545 nm) and a yellow-orange emission of Mn2+ (560 nm) resulted in the observance of white light (x=0.31, y=0.32, TC=6624 K) under midwave UV excitation (300–340 nm). Energy transfer from Ce3+→Tb3+ and Ce3+→Mn2+ was confirmed by steady state and time-resolved emission spectra, lifetime, and quantum yield measurements. The structural properties, morphology, and elemental composition of the nanophosphors were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). -- Highlights: • White light-emitting multiphase silicate nanophosphors were prepared for the first time. • Multiple crystalline silicate phases were reproduced consistently by repeated syntheses. • Energy transfer from Ce3+→Tb3+ and Ce3+→Mn2+ was confirmed by PL, lifetime, and QY measurements

  10. Calcium and magnesium silicate hydrates

    International Nuclear Information System (INIS)

    Deep geological disposals are planed to discard long-lived intermediate-level and high-level radioactive wastes. Clay-based geological barriers are expected to limit the ingress of groundwater and to reduce the mobility of radioelements. In the interaction zone between the cement and the clay based material alteration can occur. Magnesium silicate hydrates (M-S-H) have been observed due to the reaction of magnesium sulfate containing groundwater with cements or in the interaction zone between low-pH type cement and clays. M-S-H samples synthesized in the laboratory showed that M-S-H has a variable composition within 0.7 ≤ Mg/Si ≤ 1.5. TEM/EDS analyses show an homogeneous gel with no defined structure. IR and 29Si NMR data reveal a higher polymerization degree of the silica network in M-S-H compared to calcium silicate hydrates (C-S-H). The presence of mainly Q3 silicate tetrahedrons in M-S-H indicates a sheet like or a triple-chain silica structure while C-S-H is characterised by single chain-structure. The clear difference in the silica structure and the larger ionic radius of Ca2+ (1.1 Angstrom) compared to Mg2+ (0.8 Angstrom) make the formation of an extended solid solution between M-S-H and C-S-H gel improbable. In fact, the analyses of synthetic samples containing both magnesium and calcium in various ratios indicate the formation of separate M-S-H and C-S-H gels with no or very little uptake of magnesium in CS-H or calcium in M-S-H

  11. Behavior of calcium silicate hydrate in aluminate solution

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-bin; ZHAO Zhuo; LIU Gui-hua; ZHOU Qiu-sheng; PENG Zhi-hong

    2005-01-01

    Using calcium hydroxide and sodium silicate as starting materials, two kinds of calcium silicate hydrates, CaO · SiO2 · H2O and 2CaO · SiO2 · 1.17H2O, were hydro-thermally synthesized at 120 ℃. The reaction rule of calcium silicate hydrate in aluminate solution was investigated. The result shows that CaO · SiO2 · H2O is more stable than 2CaO · SiO2 · 1.17H2 O in aluminate solution and its stability increases with the increase of reaction temperature but decreases with the increase of caustic concentration. The reaction between calcium silicate hydrate and aluminate solution is mainly through two routes. In the first case, Al replaces partial Si in calcium silicate hydrate, meanwhile 3CaO · Al2 O3 · xSiO2 · (6-2x) H2 O (hydro-garnet) is formed and some SiO2 enters the solution. In the second case, calcium silicate hydrate can react directly with aluminate solution, forming hydro-garnet and Na2O · Al2O3 · 2SiO2 · nH2O (DSP). The desilication reaction of aluminate solution containing silicate could contribute partially to forming DSP.

  12. Structural and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from alite hydration in the presence of sodium and potassium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Oscar, E-mail: oamendoz@unal.edu.co [Grupo del Cemento y Materiales de Construcción (CEMATCO). Universidad Nacional de Colombia, Facultad de Minas, Medellín (Colombia); Giraldo, Carolina [Cementos Argos S.A., Medellín (Colombia); Camargo, Sergio S. [Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro/COPPE, Rio de Janeiro (Brazil); Tobón, Jorge I. [Grupo del Cemento y Materiales de Construcción (CEMATCO). Universidad Nacional de Colombia, Facultad de Minas, Medellín (Colombia)

    2015-08-15

    This research evaluates the effect of sodium and potassium hydroxide on the structure and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from the hydration of pure alite. Monoclinic (MIII) alite was synthesized and hydrated, using water-to-alite ratios of 0.5 and 0.6 and additions of 10% NaOH and KOH by weight of alite. Based on results of X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, Nuclear Magnetic Resonance and nanoindentation, two different effects of the alkaline hydroxides on the hydration reaction of alite, both at early and later ages, can be identified: (i) a differentiated hydration process, attributed to an enhancement in calcium hydroxide (CH) precipitation and a stimulation of the C-S-H nuclei; and (ii) an increase in the elastic modulus of the C-S-H aggregations, attributed to an electrostatic attraction between positive charges from the alkaline cations and negative charges from the C-S-H structure.

  13. Structural and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from alite hydration in the presence of sodium and potassium hydroxide

    International Nuclear Information System (INIS)

    This research evaluates the effect of sodium and potassium hydroxide on the structure and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from the hydration of pure alite. Monoclinic (MIII) alite was synthesized and hydrated, using water-to-alite ratios of 0.5 and 0.6 and additions of 10% NaOH and KOH by weight of alite. Based on results of X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, Nuclear Magnetic Resonance and nanoindentation, two different effects of the alkaline hydroxides on the hydration reaction of alite, both at early and later ages, can be identified: (i) a differentiated hydration process, attributed to an enhancement in calcium hydroxide (CH) precipitation and a stimulation of the C-S-H nuclei; and (ii) an increase in the elastic modulus of the C-S-H aggregations, attributed to an electrostatic attraction between positive charges from the alkaline cations and negative charges from the C-S-H structure

  14. 21 CFR 172.410 - Calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Anticaking Agents § 172.410 Calcium...

  15. LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2004-12-01

    Full Text Available The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact with divalent ions present at the surface of the shale. Also, silicates prevent the dispersion and washouts when drilling soft chalk by reacting with the Ca2+ ions present on chalk surfaces of cutting and wellbore to form a protective film. The silicate-based drilling fluid can be used during drilling hole section through shale interbeded anhydrite formations because of its superior shale stabilizing characteristics. However, drilling through the anhydrite can decrease the silicate concentration and change rheological and filtration fluid properties. So, the critical concentration of calcium ions should be investigated by lab tests. This paper details the mechanism of shale inhibition using silicate-based drilling fluid, and presents results of lab tests conducted to ascertain the effect of Ca2+ ions on silicate level in the fluid and the fluid properties.

  16. Synthesis and reaction behavior of calcium silicate hydrate in basic system

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 贺强; 李小斌; 彭志宏; 周秋生

    2004-01-01

    At the molar ratio of CaO to SiO2 of 1, with calcium hydroxide and sodium silicate, calcium silicate hydrate was synthesized at 50, 100, 170 ℃, respectively. The results show that temperature favors the formation of calcium silicate hydrate with perfect structure. When calcium silicate hydrate reacts with caustic solution, the decomposition rate of calcium silicate hydrate increases with the increasing caustic concentration and decreases with the raising synthesis temperature and the prolongation of reaction time. The decomposition rate is all less than 1.2 % in caustic solution, and XRD pattern of the residue after reaction with caustic solution is found as the same as that of original calcium silicate hydrate, which indicates the stable existence of calcium silicate hydrate in caustic solution.When reacted with soda solution, the decomposition rate increases with the increasing soda concentration and reaction time, while decreases with the synthesis temperature. The decomposition rate is more than 2% because CaO · SiO2 · H2O(CSH( Ⅰ )), except Ca5 (OH)2Si6O16 · 4H2O and Ca6Si6O17 (OH)2, is decomposed. So the synthesis temperature and soda concentration should be controlled in the process of transformation of sodium aluminosilicate hydrate into calcium silicate hydrate.

  17. Synthesis of pure zeolite P2 from calcium silicate hydrate; tobermorite

    OpenAIRE

    Nasser Y. Mostafa; Rasha A. Garib; Z. K. Heiba; Abd-Elkader, Omar H.; M. M. Al-Majthoub

    2015-01-01

    Calcium silicate hydrate phases offer the possibility to become potential zeolites precursors due to its high silica contents. Pure calcium silicate hydrate phase; tobermorite (Ca5Si6O16(OH)2·4H2O), was prepared by hydrothermal method at 175°C. Tobermorite was sucssefully converted to Zeolite P2 for the first time via refluxing in 3 M NaOH solution and in the presence of Al source. Sodium hydroxide removed calcium ions from the interlayers of calcium silicate phase and form mesoporous zeolite...

  18. 21 CFR 182.2122 - Aluminum calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  19. 21 CFR 582.2122 - Aluminum calcium silicate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent....

  20. Preparation of TiO2 nanotubes/mesoporous calcium silicate composites with controllable drug release.

    Science.gov (United States)

    Xie, Chunling; Li, Ping; Liu, Yan; Luo, Fei; Xiao, Xiufeng

    2016-10-01

    Nanotube structures such as TiO2 nanotube (TNT) arrays produced by self-ordering electrochemical anodization have been extensively explored for drug delivery applications. In this study, we presented a new implantable drug delivery system that combined mesoporous calcium silicate coating with nanotube structures to achieve a controllable drug release of water soluble and antiphlogistic drug loxoprofen sodium. The results showed that the TiO2 nanotubes/mesoporous calcium silicate composites were successfully fabricated by a simple template method and the deposition of mesoporous calcium silicate increased with the soaking time. Moreover, the rate of deposition of biological mesoporous calcium silicate on amorphous TNTs was better than that on anatase TNTs. Further, zinc-incorporated mesoporous calcium silicate coating, produced by adding a certain concentration of zinc nitrate into the soaking system, displayed improved chemical stability. A significant improvement in the drug release characteristics with reduced burst release and sustained release was demonstrated. PMID:27287140

  1. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    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. © 2010 The American Physical Society.

  2. Aggregation of Calcium Silicate Hydrate Nanoplatelets.

    Science.gov (United States)

    Delhorme, Maxime; Labbez, Christophe; Turesson, Martin; Lesniewska, Eric; Woodward, Cliff E; Jönsson, Bo

    2016-03-01

    We study the aggregation of calcium silicate hydrate nanoplatelets on a surface by means of Monte Carlo and molecular dynamics simulations at thermodynamic equilibrium. Calcium silicate hydrate (C-S-H) is the main component formed in cement and is responsible for the strength of the material. The hydrate is formed in early cement paste and grows to form platelets on the nanoscale, which aggregate either on dissolving cement particles or on auxiliary particles. The general result is that the experimentally observed variations in these dynamic processes generically called growth can be rationalized from interaction free energies, that is, from pure thermodynamic arguments. We further show that the surface charge density of the particles determines the aggregate structures formed by C-S-H and thus their growth modes. PMID:26859614

  3. NMR study of hydrated calcium silicates

    International Nuclear Information System (INIS)

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.)

  4. Premixed calcium silicate cement for endodontic applications

    OpenAIRE

    Persson, Cecilia; Engqvist, Håkan

    2011-01-01

    Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and am...

  5. Sealing of cracks in cement using microencapsulated sodium silicate

    Science.gov (United States)

    Giannaros, P.; Kanellopoulos, A.; Al-Tabbaa, A.

    2016-08-01

    Cement-based materials possess an inherent autogenous self-healing capability allowing them to seal, and potentially heal, microcracks. This can be improved through the addition of microencapsulated healing agents for autonomic self-healing. The fundamental principle of this self-healing mechanism is that when cracks propagate in the cementitious matrix, they rupture the dispersed capsules and their content (cargo material) is released into the crack volume. Various healing agents have been explored in the literature for their efficacy to recover mechanical and durability properties in cementitious materials. In these materials, the healing agents are most commonly encapsulated in macrocontainers (e.g. glass tubes or capsules) and placed into the material. In this work, microencapsulated sodium silicate in both liquid and solid form was added to cement specimens. Sodium silicate reacts with the calcium hydroxide in hydrated cement paste to form calcium-silicate-hydrate gel that fills cracks. The effect of microcapsule addition on rheological and mechanical properties of cement is reported. It is observed that the microcapsule addition inhibits compressive strength development in cement and this is observed through a plateau in strength between 28 and 56 days. The improvement in crack-sealing for microcapsule-containing specimens is quantified through sorptivity measurements over a 28 day healing period. After just seven days, the addition of 4% microcapsules resulted in a reduction in sorptivity of up to 45% when compared to specimens without any microcapsule addition. A qualitative description of the reaction between the cargo material and the cementitious matrix is also provided using x-ray diffraction analysis.

  6. Calcium silicate hydrates: Solid and liquid phase composition

    International Nuclear Information System (INIS)

    This paper presents a review on the relationship between the composition, the structure and the solution in which calcium silicate hydrate (C–S–H) is equilibrated. The silica chain length in C–S–H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space, preferentially at low calcium concentrations and thus by low Ca/Si C–S–H. Aluminium uptake in C–S–H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si, aluminium substitutes silica in the bridging position, at Ca/Si > 1 aluminium is bound in TAH. Recently developed thermodynamic models are closely related to the structure of C–S–H and tobermorite, and able to model not only the solubility and the chemical composition of the C–S–H, but also to predict the mean silica chain length and the uptake of aluminium

  7. Calcium silicate hydrates: Solid and liquid phase composition

    Energy Technology Data Exchange (ETDEWEB)

    Lothenbach, Barbara, E-mail: Barbara.lothenbach@empa.ch [Laboratory Concrete & Construction Chemistry, Empa (Switzerland); Nonat, André [ICB, UMR CNRS 6303 CNRS-Université de Bourgogne, Faculté des Sciences et Techniques, BP47870, 21078 Dijon Cedex (France)

    2015-12-15

    This paper presents a review on the relationship between the composition, the structure and the solution in which calcium silicate hydrate (C–S–H) is equilibrated. The silica chain length in C–S–H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space, preferentially at low calcium concentrations and thus by low Ca/Si C–S–H. Aluminium uptake in C–S–H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si, aluminium substitutes silica in the bridging position, at Ca/Si > 1 aluminium is bound in TAH. Recently developed thermodynamic models are closely related to the structure of C–S–H and tobermorite, and able to model not only the solubility and the chemical composition of the C–S–H, but also to predict the mean silica chain length and the uptake of aluminium.

  8. Effects of Silicate, Phosphate, and Calcium on the Stability of Aldopentoses

    Science.gov (United States)

    Nitta, Sakiko; Furukawa, Yoshihiro; Kakegawa, Takeshi

    2016-06-01

    Ribose is an important constituent of RNA: ribose connects RNA bases and forms a strand of sugar phosphates. Accumulation of ribose on prebiotic Earth was difficult because of its low stability. Improvement in the yield of ribose by the introduction of borate or silicate in a formose-like reaction has been proposed. The effects of borates have been further analyzed and confirmed in subsequent studies. Nonetheless, the effects of silicates and phosphates remain unclear. In the present study, we incubated aldopentoses in a highly alkaline aqueous solution at a moderate temperature to determine the effects of silicate or phosphate on the degradation rates of ribose and its isomeric aldopentoses. The formation of a complex of silicate (or phosphate) with ribose was also analyzed in experiments with 29Si and 31P nuclear magnetic resonance (NMR). We found that silicate or phosphate complexes of ribose were not detectable under our experimental conditions. The stability of ribose and lyxose improved after addition of 40-fold molar excess (relative to a pentose) of sodium silicate or sodium phosphate to the alkaline solution. The stability was not improved further when an 80-fold molar excess of sodium silicate or sodium phosphate was added. Calcium was removed from these solutions by precipitation of calcium salts. The drop in Ca2+ concentration might have improved the stability of ribose and lyxose, which are susceptible to aldol addition. The improvement of ribose stability by the removal of Ca2+ and by addition of silicate or phosphate was far smaller than the improvement by borate. Furthermore, all aldopentoses showed similar stability in silicate- and phosphate-containing solutions. These results clearly show that selective stabilization of ribose by borate cannot be replaced by the effects of silicate or phosphate; this finding points to the importance of borate in prebiotic RNA formation.

  9. Effects of Silicate, Phosphate, and Calcium on the Stability of Aldopentoses.

    Science.gov (United States)

    Nitta, Sakiko; Furukawa, Yoshihiro; Kakegawa, Takeshi

    2016-06-01

    Ribose is an important constituent of RNA: ribose connects RNA bases and forms a strand of sugar phosphates. Accumulation of ribose on prebiotic Earth was difficult because of its low stability. Improvement in the yield of ribose by the introduction of borate or silicate in a formose-like reaction has been proposed. The effects of borates have been further analyzed and confirmed in subsequent studies. Nonetheless, the effects of silicates and phosphates remain unclear. In the present study, we incubated aldopentoses in a highly alkaline aqueous solution at a moderate temperature to determine the effects of silicate or phosphate on the degradation rates of ribose and its isomeric aldopentoses. The formation of a complex of silicate (or phosphate) with ribose was also analyzed in experiments with (29)Si and (31)P nuclear magnetic resonance (NMR). We found that silicate or phosphate complexes of ribose were not detectable under our experimental conditions. The stability of ribose and lyxose improved after addition of 40-fold molar excess (relative to a pentose) of sodium silicate or sodium phosphate to the alkaline solution. The stability was not improved further when an 80-fold molar excess of sodium silicate or sodium phosphate was added. Calcium was removed from these solutions by precipitation of calcium salts. The drop in Ca(2+) concentration might have improved the stability of ribose and lyxose, which are susceptible to aldol addition. The improvement of ribose stability by the removal of Ca(2+) and by addition of silicate or phosphate was far smaller than the improvement by borate. Furthermore, all aldopentoses showed similar stability in silicate- and phosphate-containing solutions. These results clearly show that selective stabilization of ribose by borate cannot be replaced by the effects of silicate or phosphate; this finding points to the importance of borate in prebiotic RNA formation. PMID:26559965

  10. LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM

    OpenAIRE

    Nediljka Gaurina-Međimurec; Katarina Simon; Davorin Matanović

    2004-01-01

    The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact ...

  11. Study on silicate-calcium phosphate composite bone cement modified by sodium carbonate solution%碳酸钠液相改性硅-磷酸钙复合骨水泥研究

    Institute of Scientific and Technical Information of China (English)

    李青林; 杨帮成

    2014-01-01

    以质量分数70%的硅酸三钙(Ca3 SiO5,C3 S)和30%磷酸氢钙(CaHPO4·2H2 O,DCPD)复合得到的 DCP30粉体材料为固相,以不同浓度碳酸钠溶液为液相,得到碳酸钠改性骨水泥材料。使用 X 射线衍射(XRD)、扫描电镜(SEM)、万能材料试验机等手段对不同浓度改性材料进行表征。结果显示:添加碳酸钠液相,骨水泥初、终凝时间分别缩短至16和55 min;调控碳酸钠液相浓度,可以实现短期抗压强度优化;使用碳酸钠后,固化自发生成羟基磷灰石(HA)。浸泡模拟体液(SBF)7天,材料表面覆盖 HA 沉积层,生物活性优越。碳酸钠液相改性硅-磷酸钙复合骨水泥体系的水化性能、短期力学性能以及生物活性均优于Ca3 SiO5水泥和未改性硅-磷酸钙复合骨水泥,是一种良好的生物活性骨修复材料。%Sodium carbonate solution modified bone cement materials have been prepared using sodium carbonate solution with dif-ferent concentration as liquid phase and DCP30 powder material obtained by 70% mass fraction tricalcium silicate (Ca3 SiO5 ,C3 S) and 30% dicalcium phosphate (CaHPO4 ·2H2 O,DCPD)as the solid phase.The materials were characterized by the means of X-ray diffraction (XRD),scanning electron microscope (SEM)and mechanical test.The results show that the initial and final set-ting time of bone cement is reduced to 16 and 55 min by the addition of sodium carbonate solution.The short-term mechanical strength can be optimized by controlling the concentration of sodium carbonate solution.Hydroxyapatite (HA)can spontaneously form after the use of sodium carbonate solution.HA forms on the surface of bone-cement after immersion in SBF for 7 days,indi-cating its good bioactivity.The modified system shows better hydraulic property,bioactivity and mechanical strength than Ca3 SiO5 cement and unmodifiled silicate-calcium phosphate composite bone cement,suggesting the new system is a

  12. Properties of sodium silicate bonded sand hardened by microwave heating

    Institute of Scientific and Technical Information of China (English)

    Wang Jina; Fan Zitian; Zan Xiaolei; Pan Di

    2009-01-01

    The sodium silicate bonded sand hardened by microwave heating has many advantages,such as low sodium silicate adding quantity,fast hardening speed,high room temperature strength,good collapsibility and certain surface stability. However,it has big moisture absorbability in the air,which would lead to the compression strength and the surface stability of the sand molds being sharply reduced. In this study,the moisture absorbability of the sodium silicate bonded sand hardened by microwave heating in different humidity conditions and the effect factors were investigated. Meanwhile,the reasons for the big moisture absorbability of the sand were analyzed.Some measures to overcome the problems of high moisture absorbability,bad surface stability and sharply reducing strength in the air were discussed. The results of this study establish the foundation of green and clean foundry technology based on the microwave heating hardening sodium silicate sand process.

  13. Preparation of Hollow Calcium Silicate Microparticles by Simple Emulsion

    OpenAIRE

    Eiichi Toorisaka; Syotaro Nagamatsu; Yasunobu Saruwatari; Makoto Hirata; Tadashi Hano

    2014-01-01

    Hollow calcium silicate microparticles were prepared by mixing a water-in-oil (W/O) emulsion containing silicate ions in aqueous phase with an oil phase containing a calcium/di-2-ethylhexyl phosphoric acid (D2EHPA) complex. The inorganic precipitation reaction at the oil-water interface was accelerated by using a simple W/O emulsion. Hollow microparticles were obtained when the mole ratio of D2EHPA and calcium in the oil phase was nearly 2:1. The shell formation of the par-ticles depended on ...

  14. Immobilization of active concrete debris using soluble sodium silicates

    International Nuclear Information System (INIS)

    Demolition of biological shields will generate large quantities of active concrete debris. Sodium silicate solutions have already been shown capable of immobilizing such debris in a pellet form; this new study investigates debris immobilization via a silicate solution/debris slurry. A study of the physical and chemical properties of demolition debris has been undertaken. Laboratory scale trials have shown that only the finer (''less than''5mm) debris fractions set satisfactorily when mixed with a sodium silicate solution. Debris from ordinary portland cement concrete set more quickly than that containing a 30% pulverized fuel ash cement replacement. The particle size of the debris is a major factor in the setting process, but chemical interactions are also significant. A ratio of 1.2:1 debris:sodium silicate solution (SiO2/Na2O = 3.30), produced an optimum mix. A brief study of the logistics of a full scale process plant has also been made. (author)

  15. Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

    International Nuclear Information System (INIS)

    The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating 200 kt of carbon dioxide emissions per year, considering only the PCC used in the pulp and paper industry. A preliminary investigation of the feasibility to produce PCC from calcium silicates and the potential to replace calcium carbonate as the raw material was made. Calcium carbonate can be manufactured from calcium silicates by various methods, but only a few have been experimentally verified. The possibility and feasibility of these methods as a replacement for the current PCC production process was studied by thermodynamic equilibrium calculations using HSC software and process modelling using Aspen Plus[reg]. The results from the process modelling showed that a process that uses acetic acid for extraction of the calcium ions is a high potential option for sequestering carbon dioxide by mineral carbonation. The main obstacle seems to be the limited availability and relatively high price of wollastonite, which is a mineral with high calcium silicate content. An alternative is to use the more common, but also more complex, basalt rock instead

  16. In vitro macrophage cytotoxicity of five calcium silicates.

    OpenAIRE

    Skaug, V; Davies, R.; Gylseth, B

    1984-01-01

    Five calcium silicate minerals (two naturally occurring and three synthetic compounds) with defined morphology and chemical composition were compared for their cytotoxic and lysosomal enzyme releasing effects on unstimulated mouse peritoneal macrophages in vitro. One synthetic material, a fibrous tobermorite, was cytotoxic towards the cells, and two naturally occurring wollastonites induced selective release of beta-glucuronidase from the cells.

  17. SINTERING AND SULFATION OF CALCIUM SILICATE-ALUMINATE

    Science.gov (United States)

    The effect of sintering on the reactivity of solids at high temperature was studied. The nature of the interaction was studied with calcium silicate-aluminate reacting with SO2 between 665 and 800 C. The kinetics of the sintering and sulfation processes were measured independentl...

  18. Cementing properties of steel slag activated by sodium silicates and sodium hydroxide

    Institute of Scientific and Technical Information of China (English)

    Wen Ni; En Wang; Jianping Li; Han Sun

    2005-01-01

    Steel slag which is mainly composed of γ-CasSiO4 and other silicates or alumino-silicates is activated by sodium silicates and sodium hydroxide. The powders of such steel slag are usually inert to hydrate and subsequently have very low ability of cementing. But when sodium silicates and sodium hydroxide are used as activators the steel slag shows very good properties of cementing. When activated with NaOH solution the hardened slurry of the steel slag has a compressive strength of 11.13 MPa after being cured for 28 days. When activated with Na2SiO3 solution the samples after being cured for 28 days have an average compressive strength of 40.23 MPa. While the steel slag slurry which is only mixed with water has a compressive of 0.88 MPa after being cured for 28 days.

  19. 77 FR 21676 - Silicic Acid, Sodium Salt etc.; Tolerance Exemption

    Science.gov (United States)

    2012-04-11

    ... human skin. Since Silicic acid, sodium salt, reaction products with chlorotrimethylsilane and iso-propyl... Register of Thursday, December 8, 2011 (76 FR 76674) (FRL-9328-8), EPA issued a notice pursuant to section... human health. In order to determine the risks from aggregate exposure to pesticide inert...

  20. Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

    Directory of Open Access Journals (Sweden)

    Fedosov Sergey Viktorovich

    2014-01-01

    Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

  1. Synthesis of pure zeolite P2 from calcium silicate hydrate; tobermorite

    Directory of Open Access Journals (Sweden)

    Nasser Y. Mostafa

    2015-06-01

    Full Text Available Calcium silicate hydrate phases offer the possibility to become potential zeolites precursors due to its high silica contents. Pure calcium silicate hydrate phase; tobermorite (Ca5Si6O16(OH2·4H2O, was prepared by hydrothermal method at 175°C. Tobermorite was sucssefully converted to Zeolite P2 for the first time via refluxing in 3 M NaOH solution and in the presence of Al source. Sodium hydroxide removed calcium ions from the interlayers of calcium silicate phase and form mesoporous zeolite. The pure zeolite was obtained after extraction of Ca(OH2 with sugar solution. The zeolite products were characterized by using X-ray diffraction spectroscopy (XRD and Scanning Electron Microscopy (SEM with microanalysis (EDX. The Si/Al molar ratio of zeolite P can be controlled by vering the initinal Si/Al molar ratio. The cation-exchange capacity (CEC of the produced zeolite P was higher than those produced from fly ash.

  2. Potassium silicate and calcium silicate on the resistance of soybean to Phakopsora pachyrhizi infection

    OpenAIRE

    Maria Fernanda Cruz; Fabrício Ávila Rodrigues; Ana Paula Cardoso Diniz; Maurilio Alves Moreira; Everaldo Gonçalves de Barros

    2013-01-01

    The control of Asian Soybean Rust (ASR), caused by Phakopsora pachyrhizi, has been difficult due to the aggressiveness of the pathogen and the lack of resistant cultivars. The objective of this study was to evaluate the effects of spray of potassium silicate (PS) and soil amendment with calcium silicate (CS) on soybean resistance to ASR. The PS solution was sprayed to leaves 24 hours prior to fungal inoculation while CS was amended to the soil at thirty-five days before sowing. The infection ...

  3. Structural characterization of gel-derived calcium silicate systems.

    Science.gov (United States)

    Meiszterics, Anikó; Rosta, László; Peterlik, Herwig; Rohonczy, János; Kubuki, Shiro; Henits, Péter; Sinkó, Katalin

    2010-09-30

    The main aim of this study is to synthesize calcium silicate ceramics that exhibit suitable properties to be used for biomedical applications. In the present work, attention was paid to the understanding of processing-structure relationships. A particular effort was made to clarify the identification of Ca-O-Si bonds by means of spectroscopy. The calcium silicate systems were prepared via a sol-gel route, varying the chemical compositions, the catalyst concentration, and the temperature and time of aging and heat treatment. The processes and the phases evolved during the sol-gel procedure were determined. The bond systems were investigated by Fourier transform infrared (FTIR) and (29)Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and the aggregate structures by scanning electron microscopy (SEM), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and X-ray diffraction (XRD) measurements. PMID:20828114

  4. Dentin-cement Interfacial Interaction: Calcium Silicates and Polyalkenoates

    OpenAIRE

    Atmeh, A.R.; Chong, E. Z.; Richard, G; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline c...

  5. Characterization of modified calcium-silicate cements exposed to acidic environment

    Energy Technology Data Exchange (ETDEWEB)

    Camilleri, Josette, E-mail: josette.camilleri@um.edu.mt

    2011-01-15

    Portland cement which is used as a binder in concrete in the construction industry has been developed into a biomaterial. It is marketed as mineral trioxide aggregate and is used in dentistry. This material has been reported to be very biocompatible and thus its use has diversified. The extended use of this material has led to developments of newer versions with improved physical properties. The aim of this study was to evaluate the effect of acidic environments found in the oral cavity on fast setting calcium silicate cements with improved physical properties using a combination of techniques. Two fast setting calcium silicate cements (CSA and CFA) and two cement composites (CSAG and CFAG) were assessed by subjecting the materials to lactic acid/sodium lactate buffer gel for a period of 28 days. At weekly intervals the materials were viewed under the tandem scanning confocal microscope (TSM), and scanning electron microscope (SEM). The two prototype cements exhibited changes in their internal chemistry with no changes in surface characteristics. Since the changes observed were mostly sub-surface evaluation of surface characteristics of cement may not be sufficient in the determination of chemical changes occurring. - Research Highlights: {yields} An acidic environment affects modified fast setting calcium silicate-based cements. {yields} No surface changes are observed in acidic environment. {yields} An acidic environment causes sub-surface changes in the material chemistry which are only visible in fractured specimens. {yields} A combination of techniques is necessary in order to evaluate the chemical changes occurring.

  6. Characterization of modified calcium-silicate cements exposed to acidic environment

    International Nuclear Information System (INIS)

    Portland cement which is used as a binder in concrete in the construction industry has been developed into a biomaterial. It is marketed as mineral trioxide aggregate and is used in dentistry. This material has been reported to be very biocompatible and thus its use has diversified. The extended use of this material has led to developments of newer versions with improved physical properties. The aim of this study was to evaluate the effect of acidic environments found in the oral cavity on fast setting calcium silicate cements with improved physical properties using a combination of techniques. Two fast setting calcium silicate cements (CSA and CFA) and two cement composites (CSAG and CFAG) were assessed by subjecting the materials to lactic acid/sodium lactate buffer gel for a period of 28 days. At weekly intervals the materials were viewed under the tandem scanning confocal microscope (TSM), and scanning electron microscope (SEM). The two prototype cements exhibited changes in their internal chemistry with no changes in surface characteristics. Since the changes observed were mostly sub-surface evaluation of surface characteristics of cement may not be sufficient in the determination of chemical changes occurring. - Research Highlights: → An acidic environment affects modified fast setting calcium silicate-based cements. → No surface changes are observed in acidic environment. → An acidic environment causes sub-surface changes in the material chemistry which are only visible in fractured specimens. → A combination of techniques is necessary in order to evaluate the chemical changes occurring.

  7. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    Science.gov (United States)

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  8. Hardening of calcium hydroxide and calcium silicate binders due to carbonation and hydration

    OpenAIRE

    Cizer, Özlem; Campforts, J; Balen, Koenraad Van; Elsen, Jan; Gemert, Dionys van

    2006-01-01

    Hardening of calcium hydroxide and calcium silicate binders composed of cement, rice husk ash (RHA) and lime in different compositions were studied with mechanical strength, mercury intrusion porosimetry, thermal analysis and SEM. When cement is partially replaced with RHA and lime, hardening occurs as a result of combined hydration, pozzolanic reaction and carbonation reaction. While hydration of cement contributes to the early strength development of the mortars, carbonation is much more pr...

  9. Preparation and fluorescence property of red-emitting Eu3+-activated amorphous calcium silicate phosphor

    International Nuclear Information System (INIS)

    This paper describes the energy efficient synthesis of a red-emitting Eu3+-activated amorphous calcium silicate phosphor produced by heating a Eu3+-activated calcium silicate hydrate phosphor. Concentration quenching of the Eu3+-activated calcium silicate hydrate phosphor was not observed and the emission intensity did not decrease up to a Eu/(Ca+Eu) atomic ratio of 0.46. Heating of the Eu3+-activated calcium silicate hydrate (Eu/(Ca+Eu) atomic ratio = 0.32) phosphor produced an amorphous Eu3+-activated calcium silicate phosphor, which had a maximum emission intensity at 870 oC and emitted in the red under near-ultraviolet irradiation (395 nm). The emission intensity of the Eu3+-activated amorphous calcium silicate phosphor was about half that of a commercial BaMgAl10O17:Eu2+ phosphor, and shows great potential for application in white light-emitting diodes.

  10. Immobilisation and solidification of cesium on 11 A calcium silicate hydroxy hydrate column

    International Nuclear Information System (INIS)

    Calcium silicate hydrate closely resembling silicate mineral 11 A tobermorite has been synthesised by hydrothermal treatment of lime and silica at 175 degC. The synthetic mineral exhibits selectivity for Cs+ in the presence of strong solutions of alkali and alkaline earth cations, viz, Na+, K+, Mg2+, Ca2+, Sr2+, etc. The Al-substituted form of this mineral effectively separates cesium ion when used as an exchanger in column of size 35x5 mm (hxr). It is possible to remove 98.65±0.5%Cs+ from a mixed solution of cesium and sodium (0.0001N Cs+ + 0.5N Na+). Column separation of cesium from simulated intermediate level waste solution shows that from the first run ∼ 76% Cs+ can be immobilised on a small column, 18x10mm (hxr), having 2.0 g of exchanger. (author)

  11. EXAFS studies of sodium silicate glasses containing dissolved actinides

    International Nuclear Information System (INIS)

    Sodium silicate glasses containing dissolved Th, U, Np, and Pu have been studied using the EXAFS technique. Th4+, U4+, Np4+, and Pu4+ ions in the silicate glasses are 8-fold coordinated to oxygen neighbors. The higher valent U6+ and Np5+ ions have complex local symmetries. The U6+ ions appear in a uranyl configuration with 2 oxygen atoms at 1.85A and 4 at 2.25A from the U ion. The Np5+ local symmetry is more complex and difficult to determine uniquely. The U6+ glasses show substantial clustering of the uranium atoms. A structural model, with nearly planar uranyl sheets sandwiched between alkali and silica layers, is used to explain the U6+ EXAFS data. This model allows us to understand why U6+ ions are much more soluble in the glasses than the actinide 4+ ions. 4 references, 2 figures

  12. Synthesis of Calcium Silicate (Casio3 Using Calcium Fluoride, Quartz and Microbes

    Directory of Open Access Journals (Sweden)

    B. Gopal Krishna

    2015-09-01

    Full Text Available Microbes like bacteria, algae, fungi and virus play an important role to catalyst chemical reactions. In Nature, ores or minerals of different compounds are formed due to microbial environment and other factors like weathering. Microbial environment is also instrumental in forming calcium containing silicate minerals. Chemical reactions occur under microbial environment because microbes have the ability to control or modify different factors like pH, chemical potential and temperature during reactions. In this paper, synthesis of calcium silicate (CaSiO3 using calcium fluoride (CaF2 and quartz (SiO2 under microbial environment in a laboratory is being adopted to produce the required material. XRD technique is used to confirm the formation of CaSiO3.

  13. Comparative study on the change in index of refraction in ion-exchange interdiffusion in alkali-silicate glasses containing calcium, strontium, barium and titanium oxides

    International Nuclear Information System (INIS)

    Different ability to ion exchange from the salts of lithium-sodium-silicate glass melt containing calcium (or strontium, or barium) and titanium oxides in addition has been shown. CaO, SrO and BaO have negative effect, but TiO2 -positive one on the fullness of ion exchange of lithium-sodium and on the rate of interdiffusion in alkali-silicate glass. The value of change in index of refraction of glass with TiO2 is twice higher than glass with calcium oxide (or strontium, or barium) as the fourth component

  14. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates.

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations' setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05). PMID:26787304

  15. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    Directory of Open Access Journals (Sweden)

    Rajan Choudhary

    2015-06-01

    Full Text Available The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7 using eggshell biowaste (as calcium source, magnesium nitrate and tetraethyl orthosilicate (TEOS as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesium silicate was carried out by powder X-ray diffraction (XRD, Fourier transform infrared (FTIR and scanning electron microscopy (SEM techniques. Calcium magnesium silicate crystallite size was observed in nano regime which can effectively mimic natural bone apatite composition. In-vitro bioactivity was investigated by immersing calcium magnesium silicate pellet in simulated body fluid (SBF for three weeks. Results show effective deposition of crystallized hydroxyapatite (HAP layer on its surface and predicting its possibilities for applications in hard tissue regeneration.

  16. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    OpenAIRE

    Rajan Choudhary; Sivasankar Koppala; Sasikumar Swamiappan

    2015-01-01

    The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7) using eggshell biowaste (as calcium source), magnesium nitrate and tetraethyl orthosilicate (TEOS) as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent) and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesiu...

  17. A low-temperature sol-gel route for the synthesis of bioactive calcium silicates

    Institute of Scientific and Technical Information of China (English)

    Yong-Sen Sun; Ai-Ling Li; Fu-Jian Xu; Dong Qiu

    2013-01-01

    Sol-gel-derived bioactive calcium silicates,synthesized from calcium nitrate tetrahydrate and calcium 2-methoxyethoxide as calcium precursor respectively,were calcified under different temperatures.A series of techniques including SEM,TGA,solid 29Si NMR,nitrogen adsorption,and simulated body fluids (SBF) soaking were employed to study their textural features and in vitro bioactivity.It was confirmed that calcium 2-methoxyethoxide is a promising candidate of calcium precursor for bioactive calcium silicates stabilized under low temperatures.This has implications in fabrication of organic-inorganic hybrid composites.

  18. CO2 sequestration using calcium-silicate concrete

    International Nuclear Information System (INIS)

    This study examined the feasibility of sequestering carbon dioxide (CO2) using calcium silicate while developing a strong and durable concrete building product. In addition to offering a solution for a safe, environmentally sound manner to sequester carbon dioxide, the carbonation curing of concrete has the potential to provide a permanent storage for exhaust CO2. The calcium compounds in cement react with CO2 through the early-age carbonation curing, forming geologically stable calcium carbonates. In this study, both type 10 and type 30 Portland cements were used as CO2 binders in concretes with 0, 25, 50, and 75 per cent quartz aggregates and lightweight aggregates. The sequestration took place in a chamber under 0.5 MPa pressure at ambient temperature for a duration of 2 hours. The recovered CO2 from flue gas was simulated using a 100 per cent concentration of CO2. The CO2 uptake was quantified by direct mass gain and by an infrared-based carbon analyzer. The performance of the carbonated concrete was evaluated by its strength. In 2 hours, a CO2 uptake of 9 to 16 per cent by binder mass was achieved. The carbonation curing of concrete was found to provide better strength, stability, permeability and abrasion resistance in concrete products without steel reinforcement. 10 refs., 4 tabs., 10 figs

  19. Productivity and nutritive value of bluestem grass fertilized with calcium and magnesium silicate

    OpenAIRE

    Cinthya Souza Santana; Laura Souza Santos; Greiciele de Morais; Luiz Arnaldo Fernandes; Luciana Castro Geraseev

    2016-01-01

    This study evaluated the effect of application of calcium and magnesium silicate on the productivity, chemical composition and in situ ruminal degradation of bluestem grass (Andropogon gayanus Kunth, cv. Baeti; Embrapa 23) during the rainy and dry seasons. The design consisted of completely randomized blocks in a 6x2 factorial scheme (six silicate doses and two cutting seasons), arranged in plots subdivided over time. The plots were the calcium and magnesium silicate doses (0, 200, 400, 600, ...

  20. Synthesis of Calcium Silicate (Casio3) Using Calcium Fluoride, Quartz and Microbes

    OpenAIRE

    B. Gopal Krishna; M. Jagannadha Rao

    2015-01-01

    Microbes like bacteria, algae, fungi and virus play an important role to catalyst chemical reactions. In Nature, ores or minerals of different compounds are formed due to microbial environment and other factors like weathering. Microbial environment is also instrumental in forming calcium containing silicate minerals. Chemical reactions occur under microbial environment because microbes have the ability to control or modify different factors like pH, chemical potential and tempera...

  1. Synthesis and Characterization of Different Crystalline Calcium Silicate Hydrate: Application for the Removal of Aflatoxin B1 from Aqueous Solution

    OpenAIRE

    Lu Zeng; Ligang Yang; Shuping Wang; Kai Yang

    2014-01-01

    Different crystalline calcium silicate hydrates (CSH) were synthesized under specific hydrothermal conditions and several methods were used to analyze samples. Amorphous calcium silicate hydrates (ACSH) mainly consists of disordered calcium silicate hydrate gel (C-S-H gel) and crystalline calcium silicate hydrates (CCSH) consists of crystallized tobermorite. The adsorption of carcinogenic aflatoxin B1 (AFB1) onto ACSH and CCSH was investigated. The adsorption kinetics was studied using pseudo...

  2. Discrete element modeling of calcium-silicate-hydrate

    International Nuclear Information System (INIS)

    The discrete element method (DEM) was used to model calcium-silicate-hydrate (C-S-H) at the nanoscale. The C-S-H nanoparticles were modeled as spherical particles with diameters of approximately 5 nm. Interparticle forces included traditional mechanical contact forces, van der Waals forces and ionic correlation forces due to negatively charged C-S-H nanoparticles and ion species in the nanopores. Previous work by the authors demonstrated the DEM method was feasible in studying the properties of the C-S-H nanostructures. In this work, the simulations were performed to look into the effects of nanoparticle packing, nanoparticle morphology, interparticle forces and nanoparticle properties on the deformation mechanisms and mechanical properties of the C-S-H matrix. This work will provide insights into possible ways to improve the properties of the C-S-H matrix. (paper)

  3. Thermodynamics and kinetics of the sulfation of porous calcium silicate

    Science.gov (United States)

    Miller, R. A.; Kohl, F. J.

    1981-01-01

    The sulfation of plasma sprayed calcium silicate in flowing SO2/air mixtures at 900 and 1000 C was investigated thermogravimetrically. Reaction products were analyzed using electron microprobe and X-ray diffraction analysis techniques, and results were compared with thermodynamic predictions. The percentage, by volume, of SO2 in air was varied between 0.036 and 10 percent. At 10 percent SO2 the weight gain curve displays a concave downward shoulder early in the sulfation process. An analytical model was developed which treats the initial process as one which decays exponentially with increasing time and the subsequent process as one which decays exponentially with increasing weight gain. At lower SO2 levels the initial rate is controlled by the reactant flow rate. At 1100 C and 0.036 percent SO2 there is no reaction, in agreement with thermodynamic predictions.

  4. Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.

  5. Shrinking core models applied to the sodium silicate production process

    Directory of Open Access Journals (Sweden)

    Stanković Mirjana S.

    2007-01-01

    Full Text Available The sodium silicate production process, with the molar ratio SiO2/Na2O = 2, for detergent zeolite 4A production, is based on quartz sand dissolving in NaOH aqueous solution, with a specific molality. It is a complex process performed at high temperature and pressure. It is of vital importance to develop adequate mathematical models, which are able to predict the dynamical response of the process parameters. A few kinetic models were developed within this study, which were adjusted and later compared to experimental results. It was assumed that SiO2 particles are smooth spheres, with uniform diameter. This diameter decreases during dissolving. The influence of particle diameter, working temperature and hydroxide ion molality on the dissolution kinetics was investigated. It was concluded that the developed models are sufficiently correct, in the engineering sense, and can be used for the dynamical prediction of process parameters.

  6. Potassium silicate and calcium silicate on the resistance of soybean to Phakopsora pachyrhizi infection

    Directory of Open Access Journals (Sweden)

    Maria Fernanda Cruz

    2013-01-01

    Full Text Available The control of Asian Soybean Rust (ASR, caused by Phakopsora pachyrhizi, has been difficult due to the aggressiveness of the pathogen and the lack of resistant cultivars. The objective of this study was to evaluate the effects of spray of potassium silicate (PS and soil amendment with calcium silicate (CS on soybean resistance to ASR. The PS solution was sprayed to leaves 24 hours prior to fungal inoculation while CS was amended to the soil at thirty-five days before sowing. The infection process of P. pachyrhizi was investigated by scanning electron microscopy. The uredia on leaves of plants sprayed with PS were smaller and more compact than those observed on the leaves of plants grown in soil amended with CS or in soil non-amended with CS (control treatment. On leaves of plants from the control treatment, uredia produced many urediniospores at 9 days after inoculation, and the ASR severity was 15, 8 and 9%, respectively, for plants from control, PS and CS treatments. In conclusion, the spray of PS contributed to reduce the number of uredia per cm² of leaf area and both PS spray and CS resulted in lower ASR symptoms.

  7. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral, E-mail: obuyuk@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Yip, Sidney [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  8. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    International Nuclear Information System (INIS)

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces

  9. Intracellular calcium ions as regulators of renal tubular sodium transport.

    Science.gov (United States)

    Windhager, E; Frindt, G; Yang, J M; Lee, C O

    1986-09-15

    This review addresses the putative role of intracellular calcium ions in the regulation of sodium transport by renal tubules. Cytoplasmic calcium-ion activities in proximal tubules of Necturus are less than 10(-7) M and can be increased by lowering the electrochemical potential gradient for sodium ions across the peritubular cell membrane, or by addition of quinidine or ionomycin to peritubular fluid. Whereas lowering of the peritubular Na concentration increases cytosolic [Ca++] and [H+], ionomycin, a calcium ionophore, raises intracellular [Ca++] without decreasing pHi. The intracellular calcium-ion level is maintained by transport processes in the plasma membrane and membranes of intracellular organelles, as well as by calcium-binding proteins. Calcium ions inhibit net transport of sodium by reducing the rate of sodium entry across the luminal cell membrane. In the collecting tubule this inhibition is caused, at least in part, by an indirect reduction in the activity of the amiloride-sensitive sodium channel. PMID:2430134

  10. Biocompatibility and bioactivity of calcium silicate-based endodontic sealers in human dental pulp cells

    OpenAIRE

    Leticia Boldrin MESTIERI; GOMES-CORNÉLIO, Ana Lívia; RODRIGUES, Elisandra Márcia; SALLES, Loise Pedrosa; BOSSO-MARTELO, Roberta; Juliane Maria GUERREIRO-TANOMARU; TANOMARU-FILHO, Mário

    2015-01-01

    Mineral Trioxide Aggregate (MTA) is a calcium silicate-based material. New sealers have been developed based on calcium silicate as MTA Fillapex and MTA Plus. Objective The aim of this study was to evaluate biocompatibility and bioactivity of these two calcium silicate-based sealers in culture of human dental pulp cells (hDPCs). Material and Methods The cells were isolated from third molars extracted from a 16-year-old patient. Pulp tissue was sectioned into fragments with approximately 1 mm3...

  11. In vitro osteoblast-like and endothelial cells' response to calcium silicate/calcium phosphate cement

    International Nuclear Information System (INIS)

    This study aims to investigate the interaction between calcium silicate/calcium phosphate cement (CS/CPC) and osteogenesis, in particular the in vitro osteoblast-like and endothelial cells' response to CS/CPC. The effect of CS/CPC on cell attachment, proliferation and differentiation of murine osteoblast-like cell MC3T3-E1, as well as the influence on the cell attachment and proliferation of human umbilical vein endothelial cell (HUVEC), was studied in detail. Our results indicated that CS/CPC exhibited excellent biocompatibility to the osteoblast-like cells. Moreover, the morphology and cytoskeleton organization of MC3T3-E1 cultured on the CS/CPC disks suggested that CS/CPC induced better cell adhesion and cell spreading. Simultaneously, cell proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 were significantly improved after 3 and 7 days of culture on CS/CPC disks in comparison with CPC disks. Additionally, on CS/CPC disks, HUVEC attached well on day 1 and cell proliferation was also greatly enhanced by day 7. Collectively, these results suggest that the introduction of calcium silicate may improve the cell response involved in the osteogenesis and thus may be beneficial to further modify CPC as a better bone repairing material.

  12. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill − Part 1

    Directory of Open Access Journals (Sweden)

    M. Kermani

    2015-06-01

    Full Text Available In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investigated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF. The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The mechanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength and physical (water retention properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  13. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill L Part 1

    Institute of Scientific and Technical Information of China (English)

    M. Kermani; F.P. Hassani; E. Aflaki; M. Benzaazoua; M. Nokken

    2015-01-01

    In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investi-gated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF). The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The me-chanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength) and physical (water retention) properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP) revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  14. Preparation of calcium silicate absorbent from iron blast furnace slag.

    Science.gov (United States)

    Brodnax, L F; Rochelle, G T

    2000-09-01

    Calcium silicate hydrate (CSH) solids were prepared from hydrated lime and iron blast furnace slag in an aqueous agitated slurry at 92 degrees C. While it was hoped a minimal lime/slag ratio could be used to create near-amorphous CSH, the surface area of the product improved by increasing the lime/slag weight ratio to 2. The addition of gypsum to the lime/slag system dramatically improved the formation of surface area, creating solids with 139 m2/g after 30 hr of reaction when only a minimal amount of lime was present. The SO2 reactivity of solids prepared with gypsum greatly exceeded that of hydrated lime, achieving greater than 70-80% conversion of the alkalinity after 1 hr of reaction with SO2. The use of CaCl2 as an additive to the lime/slag system, in lieu of gypsum, also produced high-surface-area solids, 115 m2/g after 21 hr of reaction. However, the SO2 reactivity of these sorbents was relatively low given the high surface area. This emphasized that the correlation between surface area and SO2 reactivity was highly dependent on the solid phase, which was subsequently dependent on slurry composition. PMID:11055162

  15. Distribution of Water in Synthetic Calcium Silicate Hydrates.

    Science.gov (United States)

    Roosz, C; Gaboreau, S; Grangeon, S; Prêt, D; Montouillout, V; Maubec, N; Ory, S; Blanc, P; Vieillard, P; Henocq, P

    2016-07-12

    Understanding calcium silicate hydrates (CSHs) is of paramount importance for understanding the behavior of cement materials because they control most of the properties of these man-made materials. The atomic scale water content and structure have a major influence on their properties, as is analogous with clay minerals, and we should assess these. Here, we used a multiple analytical approach to quantify water distribution in CSH samples and to determine the relative proportions of water sorbed on external and internal (interlayer) surfaces. Water vapor isotherms were used to explain the water distribution in the CSH microstructure. As with many layered compounds, CSHs have external and internal (interlayer) surfaces displaying multilayer adsorption of water molecules on external surfaces owing to the hydrophilic surfaces. Interlayer water was also quantified from water vapor isotherm, X-ray diffraction (XRD), and thermal gravimetric analyses (TGA) data, displaying nonreversible swelling/shrinkage behavior in response to drying/rewetting cycles. From this quantification and balance of water distribution, we were able to explain most of the widely dispersed data already published according to the various relative humidity (RH) conditions and measurement techniques. Stoichiometric formulas were proposed for the different CSH samples analyzed (0.6 < Ca/Si < 1.6), considering the interlayer water contribution. PMID:27281114

  16. Biocompatibility of a new nanomaterial based on calcium silicate implanted in subcutaneous connective tissue of rats

    OpenAIRE

    Petrović Violeta; Opačić-Galić Vanja; Jokanović V.; Jovanović M.; Basta-Jovanović Gordana; Živković S.

    2012-01-01

    The aim of the study was to investigate rat connective tissue response to a new calcium silicate system 7, 15, 30 and 60 days after implantation. Twenty Wistar albino male rats received two tubes half-filled with a new calcium silicate system (NCSS) or MTA in subcutaneous tissue. The empty half of the tubes served as controls. Five animals were sacrificed after 7, 15, 30 and 60 days and samples of the subcutaneous tissue around implanted material were submi...

  17. Determine the Compressive Strength of Calcium Silicate Bricks by Combined Nondestructive Method

    OpenAIRE

    2014-01-01

    The paper deals with the application of combined nondestructive method for assessment of compressive strength of calcium silicate bricks. In this case, it is a combination of the rebound hammer method and ultrasonic pulse method. Calibration relationships for determining compressive strength of calcium silicate bricks obtained from nondestructive parameter testing for the combined method as well as for the L-type Schmidt rebound hammer and ultrasonic pulse method are quoted here. Calibration ...

  18. Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

    Science.gov (United States)

    Zhang, Na; Li, Hongxu; Zhao, Yazhao; Liu, Xiaoming

    2016-04-01

    Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities. PMID:26691955

  19. Aqueous deposition of calcium phosphates and silicate substituted calcium phosphates on magnesium alloys

    International Nuclear Information System (INIS)

    Attempts were made to deposit homogeneous films of calcium phosphates (CaPs) on two magnesium alloy systems, AZ31 and Mg–4Y, through an aqueous phosphating bath method. The deposition of silicate substituted CaPs by this aqueous method was also explored as silicate substitution is believed to increase the bioactivity of CaPs. The effect of doped and undoped coatings on the in vitro degradation and bioactivity of both alloy systems was studied. FTIR and EDX confirmed the deposition of Ca, P, and Si on both alloys and the coatings appeared to consist primarily biphasic mixtures of hydroxyapatite and β-TCP. These largely inhomogeneous coatings, as observed by SEM, were not shown to have any significant effect on maintaining the physiological pH of the culture medium in comparison to the uncoated samples, as the pH remained approximately in the 8.4–8.7 range. Interestingly, despite similar pH profiles between the coated and uncoated samples, CaP coatings affected the degradation of both alloys. These doped and undoped calcium phosphate coatings were observed to decrease the degradation of AZ31 whereas they increased the degradation of Mg–4Y. In vitro studies on cell attachment using MC3T3-E1 mouse osteoblasts showed that between the uncoated alloys, Mg–4Y appeared to be the more biocompatible of the two. Silicate substituted CaP coatings were observed to increase the cell attachment on AZ31 compared to bare and undoped CaPs coated samples, but did not have as great of an effect on increasing cell attachment on Mg–4Y.

  20. The natural hydrous sodium silicates from the northern bank of Lake Chad : occurrence, petrology and genesis

    OpenAIRE

    Sebag, D.; Verrecchia, Eric P.; Lee, Seong-Joo; Durand, A

    2005-01-01

    Hydrous sodium silicates sometimes associated with zeolites, form in an alkaline environment, in which there is a high concentration of dissolved silica. Such an environment existed during the Holocene in N'Guigmi interdunal depressions (Lake Chad), which led to the precipitation of various types of hydrous sodium silicates, including magadiite, kenyaite, and zeolites. Scanning electron and optical microscope observations allow several microstructures to be distinguished. These microstructure...

  1. The flame photometric determination of calcium in phosphate, carbonate, and silicate rocks

    Science.gov (United States)

    Kramer, H.

    1957-01-01

    A flame photometric method of determining calcium in phosphate, carbonate, and silicate locks has been developed Aluminum and phosphate interference was overcome by the addition of a large excess of magnesium. The method is rapid and suitable for routine analysis Results obtained are within ?? 2% of the calcium oxide content. ?? 1957.

  2. Sodium silicate solutions from dissolution of glasswastes. Statistical analysis

    Directory of Open Access Journals (Sweden)

    Torres-Carrasco, M.

    2014-05-01

    Full Text Available It has studied the solubility process of four different waste glasses (with different particle sizes, 125 µm in alkaline solutions (NaOH and NaOH/Na₂CO₃ and water as a reference and under different conditions of solubility (at room temperature, at 80°C and a mechano-chemical process. Have established the optimal conditions of solubility and generation of sodium silicates solutions, and these were: the smaller particle size (Se ha estudiado el proceso de solubilidad de cuatro diferentes residuos vítreos (con distintas granulometrías, 125 µm en disoluciones alcalinas de NaOH y NaOH/Na₂CO₃ y agua como medio de referencia y bajo distintas condiciones de solubilidad (a temperatura ambiente, a 80°C y con un proceso mecano-químico. Se han establecido las condiciones óptimas de solubilidad y generación de disoluciones de silicato sódico, y estas son: menor tamaño de partícula del residuo vítreo (inferior a 45 µm, con la disolución de NaOH/Na₂CO₃ y tratamiento térmico a 80°C durante 6 horas de agitación. El análisis estadístico realizado a los resultados obtenidos da importancia a las variables estudiadas y a las interacciones de las mismas. A través de ²⁹Si RMN MAS se ha confirmado la formación, tras los procesos de disolución, de un silicato monomérico, apto para su utilización como activador en la preparación de cementos y hormigones alcalinos.

  3. Effects of modulus and dosage of sodium silicate on limestone flotation

    OpenAIRE

    Danda S. Rao

    2010-01-01

    Sodium silicates are probably one of the oldest and most widely used industrial chemicals. Among a wide variety of applications, an important one is as a depressant in flotation. In this investigation, the effectiveness of sodium silicates of different values of modulus (silica-to-soda ratio) and dosage was investigated on a low-grade siliceous limestone sample having CaO = 45.10%, SiO2 = 15.60% and LOI = 36.03% from Jayantipuram mine of Andhra Pradesh, India. Direct flotation (flotation of c...

  4. Sorption of caesium and strontium onto calcium silicate hydrate in saline groundwater

    International Nuclear Information System (INIS)

    Full text of publication follows: In the concept for radioactive waste disposal in Japan, cement is a potential waste packaging and backfilling material and is expected to provide chemical containment. The sorption of radionuclides onto cement materials, which controls the aqueous concentrations of elements in the pore-water, is a very important parameter when considering the release of radionuclides from the near field of a cementitious radioactive waste repository. Many safety assessment calculations currently assume radionuclide retardation as linear sorption equilibrium and describe it with a distribution ratio (Rd value). In this study, the sorption mechanism is discussed by measuring the sorption isotherm of caesium, strontium (10-5 ∼ 10-2 mol dm-3) and sodium (10-4 ∼ 10-1 mol dm-3) onto Calcium Silicate Hydrate (C-S-H gel, Ca/Si 0.65 ∼ 1.2) at a liquid:solid ratio of 100:1, to support the assumption. In addition, the competitive sorption between caesium or strontium, and sodium is studied by sorption measurements using a range of sodium chloride concentration to simulate different ionic strengths in saline groundwater. The initial and equilibrated aqueous compositions were measured in the sorption experiments and it was found that caesium, strontium and sodium were sorbed by substitution for Ca in C-S-H phases by examining the mass balance. Based on the experimental results, we propose a modelling approach in which the ion-exchange model is employed and the presence of some calcium sites with different ion-exchange log K values in C-S-H is assumed by considering the composition and the structure of C-S-H. The modelling calculation results predict the measured Rd values well and also describe the competition of sorption of caesium or strontium, and sodium in the experiments. The log K values for sorption of each cation element decreased as Ca/Si ratio of C-S-H gel increased. This agrees with the trend that C-S-H gel is negatively charged at low Ca

  5. Hydration water and microstructure in calcium silicate and aluminate hydrates

    International Nuclear Information System (INIS)

    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 quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and near-infrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm-1 monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the 1H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small angle neutron scattering (USANS) and wide angle x

  6. Creating of highly active calcium-silicate phases for application in endodontics

    OpenAIRE

    Čolović B.; Jokanović V.; Jović N.

    2013-01-01

    The synthesis of active silicate phases by combined sol gel and high-temperature selfpropagating wave method, is described in this paper. They show a significant decrease of setting time and good mechanical properties, which are very important for its potential application in endodontic practice. Particularly, process of hydration of calcium silicate phases is carefully analyzed, from the aspect of phase changes during their soaking in water for 1, 3, 7 and...

  7. Kinetics and Mechanism of Adsorption of Phosphate on Fluorine-containing Calcium Silicate

    Institute of Scientific and Technical Information of China (English)

    ZHU Xinhua; ZHANG Zhao; SHEN Jun

    2016-01-01

    The nanowires-reticulated calcium silicate with a speciifc surface area more than 100 m2/g was prepared by a hydrothermal process using hydrated lime (Ca(OH)2, HL) and silica containing soluble lfuoride, which was a by-product of lfuorine industry, and the soluble lfuoride in raw silica was ifxed as CaSiF6 at the same time. The kinetic characteristics and mechanism of adsorbing phosphate by lfuorine-containing calcium silicate were investigated in the experiments of phosphorus (P) removal from aqueous solution. The results show that the prepared lfuorine-containing calcium silicate has excellent performance for adsorbing phosphate, the adsorption process appears to follow pseudo-second-order reaction kinetics and the process is mainly controlled by chemisorption. The product resulted from P adsorption is mainly composed of hydroxyapatite (HAP) and lfuorapatite (FAP), which are further used as adsorbents of heavy metal ion Cd2+ in aqueous solution and display excellent performance.

  8. Alleviating aluminum toxicity in an acid sulfate soil from Peninsular Malaysia by calcium silicate application

    Science.gov (United States)

    Elisa, A. A.; Ninomiya, S.; Shamshuddin, J.; Roslan, I.

    2016-03-01

    In response to human population increase, the utilization of acid sulfate soils for rice cultivation is one option for increasing production. The main problems associated with such soils are their low pH values and their associated high content of exchangeable Al, which could be detrimental to crop growth. The application of soil amendments is one approach for mitigating this problem, and calcium silicate is an alternative soil amendment that could be used. Therefore, the main objective of this study was to ameliorate soil acidity in rice-cropped soil. The secondary objective was to study the effects of calcium silicate amendment on soil acidity, exchangeable Al, exchangeable Ca, and Si content. The soil was treated with 0, 1, 2, and 3 Mg ha-1 of calcium silicate under submerged conditions and the soil treatments were sampled every 30 days throughout an incubation period of 120 days. Application of calcium silicate induced a positive effect on soil pH and exchangeable Al; soil pH increased from 2.9 (initial) to 3.5, while exchangeable Al was reduced from 4.26 (initial) to 0.82 cmolc kg-1. Furthermore, the exchangeable Ca and Si contents increased from 1.68 (initial) to 4.94 cmolc kg-1 and from 21.21 (initial) to 81.71 mg kg-1, respectively. Therefore, it was noted that calcium silicate was effective at alleviating Al toxicity in acid sulfate, rice-cropped soil, yielding values below the critical level of 2 cmolc kg-1. In addition, application of calcium silicate showed an ameliorative effect as it increased soil pH and supplied substantial amounts of Ca and Si.

  9. A Novel Synthesis Method of Porous Calcium Silicate Hydrate Based on the Calcium Oxide/Polyethylene Glycol Composites

    OpenAIRE

    Wei Guan; Fangying Ji; Yong Cheng; Zhuoyao Fang; Dexin Fang; Peng Yan; Qingkong Chen

    2013-01-01

    This paper proposed a novel method to prepare porous calcium silicate hydrate (CSH) based on the calcium oxide/polyethylene glycol (CaO/PEG2000) composites as the calcium materials. The porosity formation mechanism was revealed via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET), and Fourier transformed infrared spectroscopy (FT-IR). The reactivity of silica materials (SiO2) enhanced by increasing pH value. Ca2+ could not sustain rele...

  10. Effects of calcium hydroxide addition on the physical and chemical properties of a calcium silicate-based sealer

    OpenAIRE

    KUGA, Milton Carlos; DUARTE Marco Antonio Hungaro; SANT'ANNA-JÚNIOR, Arnaldo; KEINE, Kátia Cristina; FARIA, Gisele; Andrea Abi Rached DANTAS; GUIOTTI, Flávia Angélica

    2014-01-01

    Recently, various calcium silicate-based sealers have been introduced for use in root canal filling. The MTA Fillapex is one of these sealers, but some of its physicochemical properties are not in accordance with the ISO requirements. Objective: The aim of this study was to evaluate the flowability, pH level and calcium release of pure MTA Fillapex (MTAF) or containing 5% (MTAF5) or 10% (MTAF10) calcium hydroxide (CH), in weight, in comparison with AH Plus sealer. Material and Methods: The...

  11. Electrophoretic deposition of calcium silicate-reduced graphene oxide composites on titanium substrate

    DEFF Research Database (Denmark)

    Mehrali, Mehdi; Akhiani, Amir Reza; Talebian, Sepehr;

    2016-01-01

    silicate-reduced graphene oxide (CS-rGO) composites were synthesized, using an in situ hydrothermal method. CS nanowires were uniformly decorated on the rGO, with an appropriate interfacial bonding. The CS-rGO composites behaved like hybrid composites when deposited on a titanium substrate by cathodic......Calcium silicate (CS)/graphene coatings have been used to improve the biological and mechanical fixation of metallic prosthesis. Among the extraordinary features of graphene is its very high mechanical strength, which makes it an attractive nanoreinforcement material for composites. Calcium...

  12. Structure and elasticity of sodium magnesium fluoride and calcium iridium oxide at high pressures and temperatures---The perovskite and post-perovskite structure model of magnesium silicate investigated with Rietveld structure refinement and ultrasonic interferometry

    Science.gov (United States)

    Martin, Charles David

    Perovskite-structured MgSiO3 dominates the mineralogy of Earth's lower mantle. As a result, the physical properties and phase transitions of this mineral are key to understanding anomalous seismic observations of the mantle's lowermost 150-300 km---the D'' region. Recent literature suggests a post-perovskite phase of MgSiO3, experimentally observed at pressures and temperatures consistent with those expected to exist at D'', is responsible for the observed discontinuity in seismic velocity. While characterizing the crystal-chemistry, structure, and elastic properties of these two mineral enigmatic region of the Earth, many conventional experimental apparatus are unable to reproduce these extreme conditions in the laboratory. Thus, measurements of the solubility of trace elements, the elastic changes with pressure and temperature, and the Clapeyron slope between perovskite and post-perovskite phases are in desperate need; however difficult or impossible to perform on MgSiO3 directly. This dissertation addresses structure changes at high pressure and temperature occurring in materials analogous to MgSiO 3 with perovskite and post-perovskite structure, considering that conclusions drawn from this research will prove useful to a subsequent understanding of the elastic, rheological, and crystal-chemical properties of MgSiO3. Neighborite (NaMgF3) is isostructural to orthorhombic ( Pbnm) MgSiO3 perovskite. On the basis of X-ray diffraction data, previous research by Yusheng Zhao has shown that increasing temperature, or potassium substitution for sodium in the structure, drives an evolution in the average structure (> 100 A) towards a perovskite with cubic ( Pm3m) symmetry. Through utilization of pair-distribution function analysis and nuclear magnetic resonance spectroscopy, experimental techniques sensitive to short-range structure (CaIrO3 is isostructural to the post-perovskite structure of MgSiO3 (Cmcm). Utilizing X-ray powder diffraction we identify the

  13. Extraction of Soluble Sodium Silicate using Corn Cob Ash as a Silica Source

    Directory of Open Access Journals (Sweden)

    B.A. Ajayi

    2015-09-01

    Full Text Available Extraction of soluble sodium silicate was carried out in this study using corn cob ash as silica source and alkali as soda source. Initially, received corn cob was burnt in open air to obtain the corn cob ash. The obtained corn cob ash was then placed inside refractory crucible and further heating was carried out inside muffle furnace at the temperature of 6000C for 5hrs. The thermally treated corn cob ash was mixed with 3M conc. NAOH and boiled with a constant stirring in a heating glass vessel placed inside a thermostatic water bath at 800C for 4hrs and 900C for 3hrs respectively. Various analyses such as PH value, specific gravity, electrical conductivity, viscosity were conducted on the produced sodium silicate and the results were compared with the reference sodium silicate sample.

  14. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

    OpenAIRE

    Selen Küçükkaya; Mehmet Ömer Görduysus; Naciye Dilara Zeybek; Sevda Fatma Müftüoğlu

    2016-01-01

    The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM) cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After i...

  15. Growth of a bonelike apatite on chitosan microparticles after a calcium silicate treatment

    OpenAIRE

    Leonor, I. B.; Baran, E. T.; Kawashita, M.; Reis, R. L.; T Kokubo; Nakamura, T

    2008-01-01

    Bioactive chitosan microparticles can be prepared successfully by treating them with a calcium silicate solution and then subsequently soaking them in simulated body fluid (SBF). Such a combination enables the development of bioactive microparticles that can be used for several applications in the medical field, including injectable biomaterial systems and tissue engineering carrier systems. Chitosan microparticles, 0.6 lm in average size, were soaked either for 12 h in fresh calcium...

  16. Calcium Silicate-Based Cements Associated with Micro- and Nanoparticle Radiopacifiers: Physicochemical Properties and Bioactivity

    OpenAIRE

    BOSSO-MARTELO, Roberta; Juliane Maria GUERREIRO-TANOMARU; Viapiana, Raqueli; Berbert, Fábio Luis Camargo Vilella; Basso Bernardi, Maria Inês; Tanomaru-Filho, Mario

    2015-01-01

    Objective. The aim of this study was to evaluate the physicochemical properties and bioactivity of two formulations of calcium silicate-based cements containing additives (CSCM) or resin (CSCR), associated with radiopacifying agents zirconium oxide (ZrO2) and niobium oxide (Nb2O5) as micro- and nanoparticles; calcium tungstate (CaWO4); and bismuth oxide (Bi2O3). MTA Angelus was used as control. Methods. Surface features and bioactivity were evaluated by scanning electron microscopy and the ch...

  17. Sodium Silicate Behavior in Porous Media Applied for In-Depth Profile Modifications

    Directory of Open Access Journals (Sweden)

    Hossein A. Akhlaghi Amiri

    2014-03-01

    Full Text Available This paper addresses alkaline sodium silicate (Na-silicate behavior in porous media. One of the advantages of the Na-silicate system is its water-like injectivity during the placement stage. Mixing Na-silicate with saline water results in metal silicate precipitation as well as immediate gelation. This work demonstrated that low salinity water (LSW, sea water diluted 25 times could be used as a pre-flush in flooding operations. A water override phenomenon was observed during gel formation which is caused by gravity segregation. Dynamic adsorption tests in the sand-packed tubes showed inconsiderable adsorbed silicon density (about 8.5 × 10−10 kg/cm3 for a solution with 33 mg/L silicon content, which is less than the estimated mono-layer adsorption density of 1.4 × 10−8 kg/cm3. Na-silicate enhanced water sweep efficiency after application in a dual-permeability sand-pack system, without leak off into the oil-bearing low permeability (LP zone. Field-scale numerical sensitivity studies in a layered reservoir demonstrated that higher permeability and viscosity contrasts and lower vertical/horizontal permeability ratio result in lower Na-silicate leakoff into the matrix. The length of the mixing zone between reservoir water and the injected Na-silicate solution, which is formed by low salinity pre-flush, acts as a buffer zone.

  18. Thermal conductivity measurements on xonotlite-type calcium silicate by the transient hot-strip method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The experimental results of the thermal conductivities of xonotlite-type calcium silicate insulation materials were presented at different temperatures and pressures.Two appropriative surroundings,i.e.an elevated temperature surrounding from ambient temperature to 1450 K and a vacuum surrounding from atmosphere pressure to 10-3 Pa,were designed for the transient hot-strip (THS) method.The thermal conduetivities of xonotlite-type calcium silicate with four densities from ambient temperature to 1000 K and 0.045 Pa to atmospheric pressure were measured.The results show that the thermal conductivity of xunotlite-type calcium silicate decreases apparently with the fall of density,and decreases apparently with the drop of pressure,and reaches the least value at about 100 Pa.The thermal conductivity of xonotlite-type calcium silicate increases almost linearly with T3,and increases more abundantly with low density than with high density.The thermal conductivity measurement uncertainty is estimated to be approximately 3% at ambient temperature,and 6% at 800 K.

  19. Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

    Energy Technology Data Exchange (ETDEWEB)

    White, Claire E., E-mail: whitece@princeton.edu [Department of Civil and Environmental Engineering, Princeton University, Princeton (United States); Andlinger Center for Energy and the Environment, Princeton University, Princeton (United States); Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos (United States); Physics and Chemistry of Materials, Los Alamos National Laboratory, Los Alamos (United States); Daemen, Luke L.; Hartl, Monika; Page, Katharine [Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos (United States)

    2015-01-15

    The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO{sub 2} alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C{sub 3}S), blended C{sub 3}S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C{sub 3}S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.

  20. Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

    International Nuclear Information System (INIS)

    The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO2 alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C3S), blended C3S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C3S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements

  1. Photoelectron, nuclear gamma-ray and infrared absorption spectroscopic studies of neptunium in sodium silicate glass

    International Nuclear Information System (INIS)

    The valence state of neptunium ions in sodium silicate glasses prepared under reducing and oxidizing conditions has been investigated by the x-ray photoelectron, Moessbauer and optical absorption spectroscopic techniques. Results indicate that the Np ions are tetravalent in glasses prepared under reducing conditions and pentavalent in glasses prepared under oxidizing conditions

  2. On the nature of structural disorder in calcium silicate hydrates with a calcium/silicon ratio similar to tobermorite

    OpenAIRE

    Grangeon, Sylvain; Claret, Francis; Lerouge, Catherine; Warmont, Fabienne; SATO, Tsutomo; ANRAKU, Sohtoru; Numako, Chiya; LINARD, Yannick; Lanson, Bruno

    2013-01-01

    Four calcium silicate hydrates (C-S-H) with structural calcium/silicon (Ca/Si) ratios ranging from 0.82 +/- 0.02 to 0.87 +/- 0.02 were synthesized at room temperature, 50, 80, and 110 degrees C. Their structure was elucidated by collating information from electron probe micro-analysis, transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, and powder X-ray diffraction (XRD). A modeling approach specific to defective minerals was used because sample turbostrat...

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

    Science.gov (United States)

    Erd, Richard C.; Ohashi, Y.

    1984-01-01

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

  4. Structure alteration of C-S-H (calcium silicate hydrated phases) caused by sorption of caesium

    International Nuclear Information System (INIS)

    The sorption behavior of Cs onto C-S-H (calcium silicate hydrated phases) was investigated by evaluating the effect of sorption on the C-S-H structure. The C-S-H have a tobermorite-type layer structure. Each layer consists of central calcium and oxygen atoms sandwiched by silicate tetrahedral chains. Additional calcium and water are located in interlayer zones. The XRD spectra showed that the tobermorite-type layer degraded and that the sorption of Cs made the fragments of layer intergrowths much smaller. The fragmentation of the tobermorite-type layer was observed for C-S-H in contact with CsCl solution or with CsOH solution, but not for the C-S-H in contact with Na solution. Furthermore, 29Si NMR spectroscopy revealed that the sorption of Cs onto C-S-H induced cleavages of silicate chains in C-S-H. It was also suggested that the OH- ion contributed to breaking the silicate chains. (orig.)

  5. Attributes of the soil fertilized with sewage sludge and calcium and magnesium silicate

    OpenAIRE

    Geraldo R. Zuba Junio; Regynaldo A. Sampaio; Altina L. Nascimento; Luiz A. Fernandes; Natália N. de Lima; João P. Carneiro

    2015-01-01

    ABSTRACTThis study aimed to evaluate the chemical attributes of an Inceptisol cultivated with castor bean (Ricinus communis L.), variety ‘BRS Energia’, fertilized with sewage sludge compost and calcium (Ca) and magnesium (Mg) silicate. The experiment was conducted at the ICA/UFMG, in a randomized block design, using a 2 x 4 factorial scheme with three replicates, and the treatments consisted of two doses of Ca-Mg silicate (0 and 1 t ha-1) and four doses of sewage sludge compost (0, 23.81, 47....

  6. Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

    Science.gov (United States)

    Miladinovich, Daniel S.; Zhu, Dongming

    2011-01-01

    Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

  7. XPS study of CaO in sodium silicate glass

    International Nuclear Information System (INIS)

    This paper shows that CaO added to silicate glasses behaves much like Na2O in converting bridging oxygen sites to nonbridging sites. Good correspondence with model predictions was obtained but deviations were still sufficiently large to warrant attention. We speculate that some CaO may remain unreacted or that small-scale phase separation may occur. XPS core level shifts were monitored and possible charge-transfer effects were considered. Preliminary theoretical calculations utilizing a molecular-cluster approach were presented. XPS spectra for various glass compositions were simulated by appropriately combining local densities of state calculated for individual atoms. Dominant spectral features observed experimentally were found in the simulations. In conjunction with experiments, more carefully refined calculations will be subsequently examined. 7 figures

  8. Phase transformations, microstructure formation and in vitro osteoblast response in calcium silicate/brushite cement composites.

    Science.gov (United States)

    Sopcak, T; Medvecky, L; Giretova, M; Kovalcikova, A; Stulajterova, R; Durisin, J

    2016-01-01

    Self-setting simple calcium silicate/brushite (B) biocements with various Ca/P ratios were prepared by mutual mixing of both monocalcium silicate hydrate (CSH) or β-wollastonite (woll) powders with B and the addition of 2 wt% NaH2PO4 solution as a hardening liquid. The phase composition of the final composites and the texture of the surface calcium phosphate/silica layer were controlled by the starting Ca/P ratio in composites and the pH during setting. It was verified that the presence of continuous bone-like calcium phosphate coating on the surface of the samples was not essential for in vitro osteoblast proliferation. The nanocrystalline calcium deficient hydroxyapatite and amorphous silica were found as the main setting products in composite mixtures with a Ca/P ratio close to the region of the formation of deficient hydroxyapatite-like calcium phosphates. No CSH phase with a lower Ca/Si ratio was identified after transformation. The results confirmed a small effect of the monocalcium silicate addition on the compressive strength (CS) of cements up to 30 wt% (around 20-25 MPa) and a significant rise of the value in 50 woll/B cement (65 MPa). The final setting times of the cement composites varied between 5 and 43 min depending on the P/L ratio and the type of monocalcium silicate phase in the cement mixture. 10CSH/B and 50 woll/B cements with different textures but free of both the needle-like and perpendicularly-oriented hydroxyapatite particles on the surface of the samples had low cytotoxicity. PMID:27509265

  9. Sodium silicate gel induced self-mineralization of different compact and porous polymeric structures

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, A.L.; Malafaya, P.B.; Reis, R.L. [Universidade do Minho, Braga (Portugal). Dept. of Polymer Engineering

    2001-07-01

    In the present work a new methodology to produce bioactive coatings on the surface of starch based or other polymeric biomaterials is proposed. A sodium silicate gel is employed as an alternative nucleating agent to the more typical bioactive glasses, for inducing the formation of a calcium-phosphate (Ca-P) layer. The method has the advantage of being able to coat compact materials and porous 3D architectures to be used on tissue replacement and as tissue engineering scaffolds. By using this treatment, only after 6 hours of SBF immersion, it is already possible to observe the formation of very cohesive apatite-like layers that became then fragmented due to the swelling of the polymers. For the porous materials, this layer could be also observed inside the pores, clearing covering the cell walls. Furthermore, it was observed an increase of the surface hydrophilicity raising the amount of polar groups in the surface that might contribute to the formation of silanol groups that also act as apatite inductors. After 30 days of SBF immersion, the apatite-like films exhibit a partially amorphous nature and the Ca/P ratios became very closer to the value attributed to hydroxyapatite (1.67). These results are very promising for the developing of cancellous bone replacement materials and for pre-calcifying bone tissue engineering scaffolds. The present methodology can be used to coat biodegradable polymers in spite of all the correspondent difficulties arising from the continuous pH and surface changes as function of time. (orig.)

  10. A Novel Synthesis Method of Porous Calcium Silicate Hydrate Based on the Calcium Oxide/Polyethylene Glycol Composites

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2013-01-01

    Full Text Available This paper proposed a novel method to prepare porous calcium silicate hydrate (CSH based on the calcium oxide/polyethylene glycol (CaO/PEG2000 composites as the calcium materials. The porosity formation mechanism was revealed via X-ray diffraction (XRD, field-emission scanning electron microscopy (FESEM, Brunauer-Emmett-Teller (BET, and Fourier transformed infrared spectroscopy (FT-IR. The reactivity of silica materials (SiO2 enhanced by increasing pH value. Ca2+ could not sustain release from CaO/PEG2000 and reacted with caused by silica to form CSH until the hydrothermal temperature reached to 170°C, avoiding the hardly dissolved intermediates formation efficiently. The as-prepared CSH, due to the large specific surface areas, exhibited excellent release capability of Ca2+ and OH−. This porous CSH has potential application in reducing the negative environmental effects of continual natural phosphate resource depletion.

  11. Immobilisation of active concrete debris using soluble sodium silicates

    International Nuclear Information System (INIS)

    Demolition of concrete biological shields will generate large quantities of active demolition debris. The size distribution of such concrete may range from pieces of size less than one tonne down to dust. Handling and disposal methods for this material are still the subject of current research. Although the literature indicates that the mechanisms of silicate/concrete interaction are not well understood, successful setting of the smaller size fraction of concrete demolition debris can be achieved at laboratory scale. Hardened properties of the set slurry are also acceptable. A study of the full scale process has resulted in an outline design for a suitable on-site plant. Estimated capital costs of the equipment are of the order of pounds 1.1M. The project has shown that the material of less than 5mm particle size can be set by this technique. Whilst this meets the original objectives of immobilising dust, it had been hoped that the 10mm size material, (which will require removal from the larger debris before grouting can take place) could also be disposed of by the slurry setting technique. Co-disposal of slurry and large active items in the same container is unlikely to be worthwhile. 14 tabs., 5 figs., 30 refs

  12. Synthetic crystalline calcium silicate hydrate (I): cation exchange and caesium selectivity

    International Nuclear Information System (INIS)

    Solid crystalline calcium silicate hydrate (I) synthesized from equimolar amounts of Ca and Si under hydrothermal conditions at 120 oC shows cation exchange properties towards divalent metal cations such as Ni, Cu, Cd, or Hg. It also exhibits caesium selectivity in the presence of Na+. The exchange capacity and selectivity of the solid can be increased by 10 and 28 %, respectively, upon substitution of 0.01 mol of the Ca2+ in its structure by Na+. The ability of metal cation uptake by the solid was found to obey the order Ni2+ > Hg2+ > Cu2+ > Cd2+. The different affinities of calcium silicate hydrate (I) towards these ions can be used for their separation from solutions and also in nuclear waste treatment. The mechanism of the exchange reaction is discussed. (author)

  13. Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

    Directory of Open Access Journals (Sweden)

    Ana Lívia GOMES-CORNÉLIO

    2016-01-01

    Full Text Available Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA. The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2 of pure calcium silicate-based cements (CSC and modified formulations: modified calcium silicate-based cements (CSCM and three resin-based calcium silicate cements (CSCR1 (CSCR 2 (CSCR3. The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT, apoptosis/necrosis assay and comet assay. The negative control (CT- was performed with untreated cells, and the positive control (CT+ used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni’s posttest (p < 0.05, and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05. The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

  14. Effects of Calcium Lignosulfonate and Silicic Acid on Ammonium Nitrate Degradation

    Directory of Open Access Journals (Sweden)

    Ahmet Ozan Gezerman

    2014-01-01

    Full Text Available Ammonium nitrate salts are the most commonly used nitrogenous fertilizers in industry. However, storage of ammonium nitrate is problematic, since its initial properties can decline because of environmental factors, leading to large economic losses. In this study, in order to prevent the caking and degradation of ammonium nitrate, an alternative composition with additional calcium lignosulfonate and silicic acid was studied. The resulting fertilizer was analyzed by screening analysis, ion chromatography, and electron microscopy methods.

  15. Influence of Hydrothermal Temperature on Phosphorus Recovery Efficiency of Porous Calcium Silicate Hydrate

    OpenAIRE

    Wei Guan; Fangying Ji; Qingkong Chen; Peng Yan; Weiwei Zhou

    2013-01-01

    Porous calcium silicate hydrate (PCSH) was synthesized by carbide residue and white carbon black. The influence of hydrothermal temperature on phosphorus recovery efficiency was investigated by Field Emission Scanning Electron Microscopy (FESEM), Brunauer-Emmett-Teller (BET), and X-Ray Diffraction (XRD). Hydrothermal temperature exerted significant influence on phosphorus recovery performance of PCSH. Hydrothermal temperature 170°C for PCSH was more proper to recover phosphorus. PCSH could re...

  16. Study on selective sorption of 137Cs on Al-substituted calcium silicate hydroxy hydrate

    International Nuclear Information System (INIS)

    Sorption properties have been investigated by radiometric (tracer) technique at room temperature for aluminium substituted calcium silicate hydroxy hydrate, known as tobermorite. The 137Cs selectivity has been examined in presence of 1000 times concentrated solution of Na+, Ca2+, and Ba2+. The results suggest that the title phase could be used for immobilization of radioactive cesium. Cation exchange reaction takes place mainly from edge and planar surface sites along with interlayer Ca2+ sites. (author)

  17. Biomimetic apatite deposition on polymeric microspheres treated with a calcium silicate solution

    OpenAIRE

    Leonor, I. B.; Balas, F.; Kawashita, M.; Reis, R. L.; T Kokubo; Nakamura, T

    2009-01-01

    Bioactive polymeric microspheres can be prepared by means of coating them with a calcium silicate solution and subsequently soaking in a simulated body fluid (SBF). Such combination should allow for the development of bioactive microspheres for several applications in the medical field including tissue engineering carriers. Four types of polymeric microspheres, with different sizes, were used in this work: (i) ethylene-vinyl alcohol copolymer (20–30 µm), (ii) polyamide 12 with 10% magnetite (...

  18. Solubility of a new calcium silicate-based root-end filling material

    OpenAIRE

    Shishir Singh; Rajesh Podar; Shifali Dadu; Gaurav Kulkarni; Rucheet Purba

    2015-01-01

    Introduction: The purpose of this study was to compare solubility of a new calcium silicate-based cement, Biodentine with three commonly used root-end filling materials viz. glass-ionomer cement (GIC), intermediate restorative material (IRM), and mineral trioxide aggregate (MTA). Materials and Methods: Twenty stainless steel ring molds were filled with cements corresponding to four groups (n = 5). The weight of 20 dried glass bottles was recorded. Samples were transferred to bottles conta...

  19. Biomimetic apatite formation on different polymeric microspheres modified with calcium silicate solutions

    OpenAIRE

    Leonor, I. B.; Balas, F.; Kawashita, M.; Reis, R. L.; T Kokubo; Nakamura, T

    2006-01-01

    Bioactive polymeric microspheres can be produced by pre-coating them with a calcium silicate solution and the subsequent soaking in a simulated body fluid (SBF). Such combination should allow for the development of bioactive microspheres for several applications in the medical field including tissue engineering. In this work, three types of polymeric microspheres with different sizes were used: (i) ethylene-vinyl alcohol co-polymer (20-30 'm), (ii) polyamide 12 (10-30 'm) and (...

  20. Alleviating aluminum toxicity in an acid sulfate soil from Peninsular Malaysia by calcium silicate application

    OpenAIRE

    A. A. Elisa; Ninomiya, S.; J. Shamshuddin; Roslan, I.

    2016-01-01

    In response to human population increase, the utilization of acid sulfate soils for rice cultivation is one option for increasing production. The main problems associated with such soils are their low pH values and their associated high content of exchangeable Al, which could be detrimental to crop growth. The application of soil amendments is one approach for mitigating this problem, and calcium silicate is an alternative soil amendment that could be used. Therefore, the ma...

  1. Raman thresholds and rigid to floppy transitions in calcium silicate glasses

    OpenAIRE

    Micoulaut, M.; Malki, M.; Simon, P.; Canizares, A.

    2004-01-01

    Alkaline earth silicate glasses $xCaO-(1-x)SiO_2$ exhibit a well marked threshold in Raman lineshapes which can be related to the onset of network rigidity as the concentration of calcium oxide $x$ is decreased. The present results are analyzed by constraint counting algorithms and more deeply characterized by a size increasing cluster approximation that allows to perform Maxwell mechanical constraint counting beyond the usual mean-field treatment. This permits to discuss under which structur...

  2. Alleviating aluminium toxicity on an acid sulphate soils in Peninsular Malaysia with application of calcium silicate

    OpenAIRE

    A. A. Elisa; Ninomiya, S.; J. Shamshuddin; Roslan, I.

    2015-01-01

    A study was conducted to alleviate Al toxicity of an acid sulphate soils collected from paddy cultivation area in Kedah, Peninsular Malaysia. For this purpose, the collected acid sulphate soils were treated with calcium silicate. The treated soils were incubated for 120 days in submerged condition in a glasshouse. Subsamples were collected every 30 days throughout the incubation period. Soil pH and exchangeable Al showed positive effect; soil pH increased from ...

  3. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement

    Directory of Open Access Journals (Sweden)

    Marina Angelica Marciano

    2013-07-01

    Full Text Available The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO, determined by weight. Mineral trioxide aggregate (MTA was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p 3 mm equivalent of Al. The MTA group was statistically similar to the CSC / 30% BO group (p > 0.05. In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC / 50% BO group (p < 0.05. The comparison between 24 hours and 7 days showed higher ΔE for the MTA group, with statistical differences for the CSC / 15% BO and CSC / 50% BO groups (p < 0.05. After 30 days, CSC showed statistically higher ΔE values than CSC / 30% BO and CSC / 50% BO (p < 0.05. In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  4. Hydrothermal Synthesis of Xonotlite-type Calcium Silicate Insulation Material Using Industrial Zirconium Waste Residue

    Institute of Scientific and Technical Information of China (English)

    JIANG Jinguo; CUI Chong; LIU Jinqiang; LIAO Wenli

    2011-01-01

    Xonotlite-type insulation material was prepared by hydrothermal synthesis technology using industrial zirconium waste residue in this paper, and the phase analysis together with the observation of micro-morphology were also carried out by XRD, SEM and TEM. The density and thermal conductivity were measured finally. The results indicate, chlorine ion impurity contained in zirconium waste residue can be removed effectively via water washed process, and the reactive activity of silicon dioxide is almost not affected,which make it be a good substitution of silicon material for the preparation of calcium silicate insulation material by hydrothermal synthesis technique. The density and thermal conductivity of xonotlite-type calcium silicate insulation material obtained by hydrothermal synthesis technique can reach 159 kg/m3, 0.049 W/(m·°C), respectively, meeting with National Standard well, when synthesis conditions are selected as follows: Ca/Si molar ratio equal to 1, synthesis temperature at 210 ℃ and kept for 8 hrs. It provides a new approach to realize lightweight and low thermal conductivity of calcium silicate insulation material.

  5. Vibrational investigation of calcium-silicate cements for endodontics in simulated body fluids

    Science.gov (United States)

    Taddei, Paola; Modena, Enrico; Tinti, Anna; Siboni, Francesco; Prati, Carlo; Gandolfi, Maria Giovanna

    2011-05-01

    Calcium-silicate MTA (Mineral Trioxide Aggregate) cements have been recently developed for oral and endodontic surgery. This study was aimed at investigating commercial (White ProRoot MTA, White and Grey MTA-Angelus) and experimental (wTC-Bi) accelerated calcium-silicate cements with regards to composition, hydration products and bioactivity upon incubation for 1-28 days at 37 °C, in Dulbecco's Phosphate Buffered Saline (DPBS). Deposits on the surface of the cements and the composition changes during incubation were investigated by micro-Raman and ATR/FT-IR spectroscopy, and pH measurements. Vibrational techniques disclosed significant differences in composition among the unhydrated cements, which significantly affected the bioactivity as well as pH, and hydration products of the cements. After one day in DPBS, all the cements were covered by a more or less homogeneous layer of B-type carbonated apatite. The experimental cement maintained a high bioactivity, only slightly lower than the other cements and appears a valid alternative to commercial cements, in view of its adequate setting time properties. The bioactivity represents an essential property to favour bone healing and makes the calcium-silicate cements the gold standard materials for root-apical endodontic surgery.

  6. Silicate anion structural change in calcium silicate hydrate gel on dissolution of hydrated cement

    International Nuclear Information System (INIS)

    High pH conditions of aqueous solutions in a radioactive waste repository can be brought about by dissolution of cementitious materials. In order to clarify the mechanisms involved in maintaining this high pH for long time, we investigated the dissolution phenomena of OPC hydrate. In the present research, leaching tests on powdered cement hydrates were conducted by changing the ratio of mass of leaching water to mass of OPC hydrate (liquid/solid ratio) from 10 - 2,000 (wt/wt). Ordinary Portland Cement hydrate was contacted with deionized water and placed in a sealed bottle. After a predetermined period, the solid was separated from the solution. From the results of XRD analysis on the solid phase and the Ca concentration in the aqueous phase, it was confirmed that Ca(OH)2 was preferentially dissolved when the liquid/solid ratio was 10 or 100 (wt/wt), and that C-S-H gel as well as Ca(OH)2 were dissolved when the liquid/solid ratio was 500 (wt/wt) or larger. 29Si-NMR results showed that the silicate anion chain of the C-S-H gel became longer when the liquid/solid ratio was 500 (wt/wt) or greater. This indicates that leaching of OPC hydrate results in a structural change of C-S-H gel. (author)

  7. Quantitative Evaluation by Glucose Diffusion of Microleakage in Aged Calcium Silicate-Based Open-Sandwich Restorations

    OpenAIRE

    Camps, J.; Tassery, H.; Koubi, G.; Elmerini, H.; Koubi, S.

    2012-01-01

    This study compared the in vitro marginal integrity of open-sandwich restorations based on aged calcium silicate cement versus resin-modified glass ionomer cement. Class II cavities were prepared on 30 extracted human third molars. These teeth were randomly assigned to two groups ( = 1 0 ) to compare a new hydraulic calcium silicate cement designed for restorative dentistry (Biodentine, Septodont, Saint Maur des Fossés, France) with a resin-modified glass ionomer cement (Ionolux, Voco, Cuxh...

  8. The sealing of excavation damaged zones in salt formations using sodium silicate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Engelhardt, Hans-Joachim; Schmidt, Holger; Borstel, Lieselotte von [DBE TECHNOLOGY GmbH, Peine (Germany). Dept. of Repository Safety

    2015-07-01

    Since many decades, pressure grouting is an effective technique of civil engineering for sealing and stabilization purposes. Due to the potential contamination of fluids, grouting is of particular importance in repositories of radioactive waste. Traditional grouts for the sealing of fine fractures are sodium silicate solutions. Laboratory and field investigations prove that the particle-free solutions can be used to permanently seal excavation damaged zones (EDZ) in salt formations, because the solid reaction products are inert or almost insoluble. EDZ permeabilities of 10{sup -17} m{sup 2} can be achieved and were determined on the basis of the injection pressures and flow rates. High grouting pressures were realized as local test loadings. Laboratory tests show the fixation of Co{sup 2+}, Ni{sup 2+}, Sr{sup 2+}, Ba{sup 2+}, [UO{sub 2}]{sup 2+} and illustrate that sodium silicates may act additionally as a chemical barrier.

  9. The sealing of excavation damaged zones in salt formations using sodium silicate solutions

    International Nuclear Information System (INIS)

    Since many decades, pressure grouting is an effective technique of civil engineering for sealing and stabilization purposes. Due to the potential contamination of fluids, grouting is of particular importance in repositories of radioactive waste. Traditional grouts for the sealing of fine fractures are sodium silicate solutions. Laboratory and field investigations prove that the particle-free solutions can be used to permanently seal excavation damaged zones (EDZ) in salt formations, because the solid reaction products are inert or almost insoluble. EDZ permeabilities of 10-17 m2 can be achieved and were determined on the basis of the injection pressures and flow rates. High grouting pressures were realized as local test loadings. Laboratory tests show the fixation of Co2+, Ni2+, Sr2+, Ba2+, [UO2]2+ and illustrate that sodium silicates may act additionally as a chemical barrier.

  10. On the nature of structural disorder in calcium silicate hydrates with a calcium/silicon ratio similar to tobermorite

    International Nuclear Information System (INIS)

    Four calcium silicate hydrates (C-S-H) with structural calcium/silicon (Ca/Si) ratios ranging from 0.82 ± 0.02 to 0.87 ± 0.02 were synthesized at room temperature, 50, 80, and 110 °C. Their structure was elucidated by collating information from electron probe micro-analysis, transmission electron microscopy, extended X-ray absorption fine structure spectroscopy, and powder X-ray diffraction (XRD). A modeling approach specific to defective minerals was used because sample turbostratism prevented analysis using usual XRD refinement techniques (e.g. Rietveld analysis). It is shown that C-S-H with Ca/Si ratio of ∼ 0.8 are structurally similar to nano-crystalline turbostratic tobermorite, a naturally occurring mineral. Their structure thus consists of sheets of calcium atoms in 7-fold coordination, covered by ribbons of silicon tetrahedra with a dreierketten (wollastonite-like) organization. In these silicate ribbons, 0.42 Si per bridging tetrahedron are missing. Random stacking faults occur systematically between successive layers (turbostratic stacking). Layer-to-layer distance is equal to 11.34 Å. Crystallites have a mean size of 10 nm in the a–b plane, and a mean number of 2.6–2.9 layers stacked coherently along the c* axis

  11. In vitro osteoblast-like and endothelial cells' response to calcium silicate/calcium phosphate cement

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Qinghui; Qian Jiangchao [State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhou Huanjun; Yuan Yuan; Mao Yuhao; Liu Changsheng, E-mail: jiangchaoqian@ecust.edu.c, E-mail: csliu@sh163.ne [Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China)

    2010-06-01

    This study aims to investigate the interaction between calcium silicate/calcium phosphate cement (CS/CPC) and osteogenesis, in particular the in vitro osteoblast-like and endothelial cells' response to CS/CPC. The effect of CS/CPC on cell attachment, proliferation and differentiation of murine osteoblast-like cell MC3T3-E1, as well as the influence on the cell attachment and proliferation of human umbilical vein endothelial cell (HUVEC), was studied in detail. Our results indicated that CS/CPC exhibited excellent biocompatibility to the osteoblast-like cells. Moreover, the morphology and cytoskeleton organization of MC3T3-E1 cultured on the CS/CPC disks suggested that CS/CPC induced better cell adhesion and cell spreading. Simultaneously, cell proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 were significantly improved after 3 and 7 days of culture on CS/CPC disks in comparison with CPC disks. Additionally, on CS/CPC disks, HUVEC attached well on day 1 and cell proliferation was also greatly enhanced by day 7. Collectively, these results suggest that the introduction of calcium silicate may improve the cell response involved in the osteogenesis and thus may be beneficial to further modify CPC as a better bone repairing material.

  12. Interaction of calcium silicate hydrates (C-S-H), the main components of cement, with alkaline chlorides, analogy with clays

    International Nuclear Information System (INIS)

    This work, belonging to a more general study on the structure and reactivity of cement, deals with the experimental and theoretical analysis of the interaction of alkaline chlorides with calcium silicate hydrates (C-S-H), the main components of cement paste. The interaction of alkaline cations with C-S-H is interfacial, involving both electrostatic and surface complexation mechanisms. The C-S-H surface is constituted of silanol sites, partially dissociated due to the high pH of the interstitial solution. The calcium ions, present in large amounts in the equilibrium solution of C-S-H, constitute potential determining ions for the C-S-H surface. The alkaline ions seem to compete with calcium for the same surface sites. The adsorption isotherms show that caesium presents a better affinity than sodium and lithium for the C-S-H surface. Moreover, solid-state NMR suggests that caesium forms with the surface sites inner-sphere complexes, whereas sodium seems to keep its hydration sphere. These results are in agreement with zeta potential measurements, which let suppose a specific adsorption of caesium ions, and an indifferent behaviour of both other alkaline ions. A model for the C-S-H surface was proposed, from the electric double layer model, and mass action laws expressing the complexation of the different ionic species with the silanol sites. The whole study relies on a structural analogy with smectites, some clays presenting well-known cationic adsorption properties. The structural similarity between both minerals is enhanced by some similarities of reactivity, though significant behaviour differences could also be noted. (author)

  13. Scientific Opinion on the safety evaluation of the active substances, sodium carbonate peroxyhydrate coated with sodium carbonate and sodium silicate, bentonite, sodium chloride, sodium carbonate for use in active food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2013-04-01

    Full Text Available This scientific opinion of the Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety evaluation of the powder mixture of the active substances sodium carbonate peroxyhydrate coated with sodium carbonate and sodium silicate (FCM substance No 1009, bentonite (CAS No 1302-78-9, FCM No 393, sodium chloride (CAS No 7647-14-5, FCM No 985, sodium carbonate (CAS No 497-19-8, FCM No 1008 which are intended to be used as combined oxygen generator and carbon dioxide absorber in packaging containing whole fresh fruits. The powder mixture is placed in a nonwoven polyethylene sachet separated from the food by a pad. In the presence of moisture, sodium carbonate peroxyhydrate first decomposes into sodium carbonate and hydrogen peroxide which decomposes into water and oxygen. Sodium carbonate reacts with carbon dioxide to form sodium bicarbonate. Because the sachet is not placed in direct contact with the food or food exudates, only hydrogen peroxide which decomposes to water and oxygen may be released with no other potential migration of volatile compounds. Based on the conclusion drawn in the EU Risk Assessment Report that hydrogen peroxide is not classified as a mutagen and the results from a subchronic toxicity study with hydrogen peroxide, the Panel concluded that hydrogen peroxide does not raise a safety concern under the intended conditions of use. Therefore the CEF Panel concluded that sodium carbonate peroxyhydrate coated with sodium carbonate and sodium silicate, bentonite, sodium chloride and sodium carbonate do not raise a safety concern for the consumer when used as combined oxygen generator and carbon dioxide absorber, for packaging of whole fruits. The substances should be used in sachets which prevent the release of the powder mixture into the food. Sachets should not be in direct contact with food or food exudates.

  14. Use of Sodium Silicate from Rice Husk Ash Basic Materials for Coating Electrolytes in the Synthesis of Magnetite Nanoparticles22

    OpenAIRE

    Syahrul, Muh

    2013-01-01

    Magnetite nanoparticles had a measurement about 6,76 nm was synthesized through electrochemical technique in the synthetic sodium silicate solution which was gained through the extraction process of silica which content in the rice husk ash by using NaOH 1,5 M. Sodium silicate functions as electrolyte and simultaneously as a coated to maintain the size of the magnetite particle which was formed through electrolysis process. The synthesis of magnetite nanoparticles was implemented in the varia...

  15. Effects of calcium hydroxide addition on the physical and chemical properties of a calcium silicate-based sealer

    Directory of Open Access Journals (Sweden)

    Milton Carlos KUGA

    2014-06-01

    Full Text Available Recently, various calcium silicate-based sealers have been introduced for use in root canal filling. The MTA Fillapex is one of these sealers, but some of its physicochemical properties are not in accordance with the ISO requirements. Objective: The aim of this study was to evaluate the flowability, pH level and calcium release of pure MTA Fillapex (MTAF or containing 5% (MTAF5 or 10% (MTAF10 calcium hydroxide (CH, in weight, in comparison with AH Plus sealer. Material and Methods: The flowability test was performed according to the ISO 6876:2001 requirements. For the pH level and calcium ion release analyses, the sealers were placed individually (n=10 in plastic tubes and immersed in deionized water. After 24 hours, 7 and 14 days, the water in which each specimen had been immersed was evaluated to determine the pH level changes and calcium released. Flowability, pH level and calcium release data were analyzed statistically by the ANOVA test (α=5%. Results: In relation to flowability: MTAF>AH Plus>MTAF5>MTAF10. In relation to the pH level, for 24 h: MTAF5=MTAF10=MTAF>AH Plus; for 7 and 14 days: MTAF5=MTAF10>MTAF>AH Plus. For the calcium release, for all periods: MTAF>MTAF5=MTAF10>AH Plus. Conclusions: The addition of 5% CH to the MTA Fillapex (in weight is an alternative to reduce the high flowability presented by the sealer, without interfering in its alkalization potential.

  16. A cubic calcium oxynitrido-silicate, Ca2.89Si2N1.76O4.24

    OpenAIRE

    Ali Sharafat; Pedro Berastegui; Saeid Esmaeilzadeh; Lars Eriksson; Jekabs Grins

    2011-01-01

    The title compound, tricalcium oxynitride silicate, with composition Ca3-xSi2N2-2xO4+2x (x ≃ 0.12), is a perovskite-related calcium oxynitrido silicate containing isolated oxynitrido silicate 12-rings. The N atoms are statistically disordered with O atoms (occupancy ratio N:O = 0.88:0.12) and occupy the bridging positions in the 12 ring oxynitrido silicate anion, while the remaining O atoms are located at the terminal positions of the Si(O,N)4 tetrahedra. The majority of the Ca2+ ca...

  17. Development of an immobilization process for heavy metal containing galvanic solid wastes by use of sodium silicate and sodium tetraborate

    International Nuclear Information System (INIS)

    Highlights: • A new physico-chemical process below 1000 °C for immobilization of galvanic sludges. • Sodium tetraborate and sodium silicate have been used as additives. • A strategy for adjustment of solid waste/additive mixture composition is presented. • Strategy is valid for wastes of hydrometallurgical and electro-plating processes. • Lower energy consumption and treated waste volume, shorter process time are provided. - Abstract: Heavy metal containing sludges from wastewater treatment plants of electroplating industries are designated as hazardous waste since their improper disposal pose high risks to environment. In this research, heavy metal containing sludges of electroplating industries in an organized industrial zone of Istanbul/Turkey were used as real-sample model for development of an immobilization process with sodium tetraborate and sodium silicate as additives. The washed sludges have been precalcined in a rotary furnace at 900 °C and fritted at three different temperatures of 850 °C, 900 °C and 950 °C. The amounts of additives were adjusted to provide different acidic and basic oxide ratios in the precalcined sludge-additive mixtures. Leaching tests were conducted according to the toxicity characteristic leaching procedure Method 1311 of US-EPA. X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and flame atomic absorption spectroscopy (FAAS) have been used to determine the physical and chemical changes in the products. Calculated oxide molar ratios in the precalcined sludge-additive mixtures and their leaching results have been used to optimize the stabilization process and to determine the intervals of the required oxide ratios which provide end-products resistant to leaching procedure of US-EPA. The developed immobilization-process provides lower energy consumption than sintering-vitrification processes of glass–ceramics

  18. The activity of NaOH buffered by silicate solids in molten sodium acetate-water at 317 degree C

    International Nuclear Information System (INIS)

    Silica and sodium acetate are present in the steam generator tube sheet crevices of many nuclear power plants. Trace solutes in the condensate are tremendously concentrated in the crevices by boiling. Sparingly soluble sodium silicates and other solids precipitate from the crevice liquid, leaving an extremely concentrated molten mixture of water, sodium acetate and other salts. The precipitates buffer the activity of sodium hydroxide in the superheated liquid that remains. The activity of NaOH corresponding to the buffers quartz/sodium disilicate and sodium disilicate/sodium metasilicate at 317 degree C has been determined experimentally. The sodium hydroxide content of a sodium acetate-water melt buffered by these reactions was determined by chemical analysis, and the corresponding activity of NaOH at temperature was calculated using the recently published Pitzer-Simonson Model of molten salt-water mixtures. The molten mixture of sodium acetate and water plays the role of solvent in these experiments and calculations. The free energies of formation of solid sodium silicates at 317 degree C were also determined. The activity of NaOH corresponding to other silicate and phosphate buffers was calculated using published thermodynamic data and estimated from phase diagrams

  19. DFT simulation of the adsorption of sodium silicate species on kaolinite surfaces

    Science.gov (United States)

    Han, Yonghua; Liu, Wenli; Chen, Jianhua

    2016-05-01

    The adsorption of Si(OH)4 molecules and the SiO(OH)3- anion on kaolinite surfaces was studied using density functional theory (DFT) calculations to investigate the dispersion mechanism of sodium silicate on kaolinite particles. The calculated results demonstrate that Si(OH)4 and SiO(OH)3- primarily adsorb on kaolinite Al-terminated (0 0 1) surfaces. Both Si(OH)4 and SiO(OH)3- bond with the Al-terminated surface by hybridization of the O2p orbital and H1s orbital. The unbonded O atom of SiO(OH)3- is notably active. The SiO(OH)3- anion can add more electrons and form a stronger electrostatic interaction with the Al surface. The adsorption of SiO(OH)3- is more stable than the adsorption of Si(OH)4. After adsorption of sodium silicate, the surfaces of kaolinite can become more hydrophilic and carry more negative charge. Therefore, the adsorption of silicate species makes the fine particles of kaolinite disperse in aqueous solution more easily.

  20. 40 CFR 721.10018 - Calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Calcium hydroxide oxide silicate (Ca6... New Uses for Specific Chemical Substances § 721.10018 Calcium hydroxide oxide silicate (Ca6(OH)2O2... substance identified as calcium hydroxide oxide silicate (Ca6(OH)2O2(Si2O5)3) (PMN P-01-442; CAS No....

  1. Biocompatibility and bioactivity of calcium silicate-based endodontic sealers in human dental pulp cells

    Directory of Open Access Journals (Sweden)

    Leticia Boldrin MESTIERI

    2015-10-01

    Full Text Available Mineral Trioxide Aggregate (MTA is a calcium silicate-based material. New sealers have been developed based on calcium silicate as MTA Fillapex and MTA Plus.Objective The aim of this study was to evaluate biocompatibility and bioactivity of these two calcium silicate-based sealers in culture of human dental pulp cells (hDPCs.Material and Methods The cells were isolated from third molars extracted from a 16-year-old patient. Pulp tissue was sectioned into fragments with approximately 1 mm3 and kept in supplemented medium to obtain hDPCs adherent cultures. Cell characterization assays were performed to prove the osteogenic potential. The evaluated materials were: MTA Plus (MTAP; MTA Fillapex (MTAF and FillCanal (FC. Biocompatibility was evaluated with MTT and Neutral Red (NR assays, after hDPCs exposure for 24 h to different dilutions of each sealer extract (1:2, 1:3 and 1:4. Unexposed cells were the positive control (CT. Bioactivity was assessed by alkaline phosphatase (ALP enzymatic assay in cells exposed for one and three days to sealer extracts (1:4 dilution. All data were analyzed by ANOVA and Tukey post-test (p≤0.05%.Results MTT and NR results showed suitable cell viability rates for MTAP at all dilutions (90-135%. Cells exposed to MTAF and FC (1:2 and 1:4 dilutions showed significant low viability rate when compared to CT in MTT. The NR results demonstrated cell viability for all materials tested. In MTAP group, the cells ALP activity was similar to CT in one and three days of exposure to the material. MTAF and FC groups demonstrated a decrease in ALP activity when compared to CT at both periods of cell exposure.Conclusions The hDPCs were suitable for the evaluation of new endodontic materialsin vitro. MTAP may be considered a promising material for endodontic treatments.

  2. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    International Nuclear Information System (INIS)

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m1/2) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability

  3. Biocompatibility of a new nanomaterial based on calcium silicate implanted in subcutaneous connective tissue of rats

    Directory of Open Access Journals (Sweden)

    Petrović Violeta

    2012-01-01

    Full Text Available The aim of the study was to investigate rat connective tissue response to a new calcium silicate system 7, 15, 30 and 60 days after implantation. Twenty Wistar albino male rats received two tubes half-filled with a new calcium silicate system (NCSS or MTA in subcutaneous tissue. The empty half of the tubes served as controls. Five animals were sacrificed after 7, 15, 30 and 60 days and samples of the subcutaneous tissue around implanted material were submitted to histological analysis. The intensity of inflammation was evaluated based on the number of inflammatory cells present. Statistical analysis was performed using one way ANOVA and Holm Sidak's multiple comparison tests. Mild to moderate inflammatory reaction was observed after 7, 15 and 30 days around a NCSS while mild inflammatory reaction was detected after 60 days of implantation. In the MTA group, mild to moderate inflammatory reaction was found after 7 and 15 days while mild inflammatory reaction was present after 30 and 60 days. There was no statistically significant difference in the intensity of inflammatory reactions between the tested materials and control groups in any experimental period (ANOVA p>0.05. Regarding the intensity of inflammatory reactions at different experimental periods, a statistically significant difference was observed between 7 and 30 days, 7 and 60 days and 15 to 60 days for both materials. For the controls, a statistically significant difference was found between 7 and 60 days and 15 and 60 days of the experiment (Holm Sidak < p 0.001. Subcutaneous tissue of rats showed good tolerance to a new calcium silicate system. Inflammatory reaction was similar to that caused by MTA. [Projekat Ministarstva nauke Republike Srbije, br. 172026

  4. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Pei [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Wei, Pingpin [Cancer Research Institute, Central South University, Changsha 410078 (China); Li, Pengjian; Gao, Chengde [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Shuai, Cijun, E-mail: shuai@csu.edu.cn [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, PR China, (China); Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425 (United States); Peng, Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha 410078 (China)

    2014-11-15

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

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

    Science.gov (United States)

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

    2013-05-01

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

  6. Characterization of ion distributions near the surface of sodium-containing and sodium-depleted calcium aluminosilicate glass melts

    International Nuclear Information System (INIS)

    The distribution of cation and anion components of sodium containing calcium aluminosilicate glass was studied by classical molecular dynamics simulations in a high temperature melt in the bulk and at the vacuum-melt interface. A significant redistribution of the sodium and non-bridging oxygen ions was observed. Subsequently, a sodium depleted calcium aluminosilicate glass melt was simulated to determine the sensitivity of the redistribution of ions near the vacuum-melt interface to the presence of sodium ions. It is found that the thermodynamic equilibrium condition near a surface favors the enrichment of non-bridging oxygen ions that is closely associated with enrichment of the sodium ions

  7. Specific interaction of cesium with the surface of calcium silicate hydrates

    International Nuclear Information System (INIS)

    The sorption of cesium at the calcium silicate hydrates (CSH) surface was investigated, both through sorption isotherm data and by solid-state NMR experiments. The sorption ability of CSH towards cesium is favored for low solid Ca/Si molar ratios, in agreement with the negative surface charge they develop then. A significant proportion of these sorbed cesium cations remains tightly bound to the surface sites forming, in dehydrated CSH, inner-sphere complexes, which can not be removed by alcohol washing. Chloride seems to present a lower affinity for CSH, even for high Ca/Si molar ratios, where the surface charge becomes positive. (orig.)

  8. Sorption study of 137Cs on Al-substituted calcium silicate hydroxy hydrate

    International Nuclear Information System (INIS)

    Calcium silicate hydroxy hydrate is also known as tobermorite and it is similar to Ca5AlxSi6-xO18H24.nH2O (where x = 0.025) in composition. Sorption studies have been investigated by radiometric technique at room temperature. The 137Cs selectivity has been examined in presence of 1000 times concentrated solution of Na+, Ca2+ and Ba2+. The data suggests that tobermorite could be used for immobilisation of radioactive caesium. (author)

  9. The Performance of Calcium Silicate Board Partition Fireproof Drywall Assembly with Junction Box under Fire

    OpenAIRE

    Yinuo Wang; Ying-Ji Chuang; Ching-Yuan Lin

    2015-01-01

    This study uses a metal stud partition fireproof drywall measuring 83 mm in thickness as a test specimen to explore the impact of an embedded junction box on the firefighting performance of the wall through one time of standard fire test on a 300 cm × 300 cm area and five times of standard fire test on a 120 cm × 120 cm area. The results show that the quality of calcium silicate board plays a big role in the fireproof effectiveness. The embedded junction box located on the backside of the f...

  10. 21 CFR 872.3490 - Carboxymethylcellulose sodium and/or polyvinylmethylether maleic acid calcium-sodium double salt...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Carboxymethylcellulose sodium and/or... DENTAL DEVICES Prosthetic Devices § 872.3490 Carboxymethylcellulose sodium and/or polyvinylmethylether maleic acid calcium-sodium double salt denture adhesive. (a) Identification. A...

  11. Simple preparation and initial characterization of semi-amorphous hollow calcium silicate hydrate nanoparticles by ammonia-hydrothermal-template techniques

    International Nuclear Information System (INIS)

    Semi-amorphous hollow calcium silicate hydrate nanoparticles (CS10d120Hac) were successfully synthesized via simple ammonia-hydrothermal-template approach (AHT) followed by acid treatment. Results revealed that the newly synthesized samples had homogenous hollow nano-interior wherein the shell wall contained semi-amorphous calcium silicate hydrate. The AHT intensified the formation of a stronger electrostatic interaction (Si–O–Ca) from the weaker electrostatic contact composed of silicate wall-calcium hydroxide interaction (Si–OH–Ca) forming a thin semi-amorphous calcium silicate hydrate shell wall. This is also a convenient way for structural stability of the hollow CS10d120Hac. The CS10d120Hac showed a relatively higher surface area, which is uniquely rare especially if compared with bulk calcium silicate particles. This CS10d120Hac can be selectively functionalized with multiple organic and inorganic groups. Hence, this work may open a new route for the formation of hybrid hollow bio-active particles.

  12. Fluorescent properties of a blue-to green-emitting Ce3+, Tb3+ codoped amorphous calcium silicate phosphors

    International Nuclear Information System (INIS)

    Ce3+, Tb3+ codoped amorphous calcium silicate phosphor was prepared by heating (830 °C for 30 min) Ce3+, Tb3+ codoped calcium silicate hydrate phosphor formed by liquid-phase reaction. The excitation peak wavelength of the resulting phosphor was 330 nm and the emission peak wavelengths were at 544 nm, attributed to the 5D4→7F5 transition of Tb3+, and at 430–470 mm, attributed to Ce3+. The intensity ratio of the two peaks could be freely controlled by varying the Tb/Ca atomic ratio of the Ce3+, Tb3+ codoped amorphous calcium silicate phosphor, allowing light to be emitted over a wide range from blue to green. It was clarified that energy transfer exists from Ce3+ to Tb3+. - Graphical abstract: Ce3+, Tb3+ codoped calcium silicate hydrate phosphor was synthesized by liquid-phase reaction. This was heated at 830 °C to obtain a Ce3+, Tb3+ codoped amorphous calcium silicate phosphor. Under 330 nm excitation, this phosphor showed emission peaks at 430–470 nm and 542 nm. The luminescent color could be continuously changed blue to green with increasing Tb/Ca atomic ratio. It was clarified that electron transfer from Ce3+ to Tb3+ is occurring.

  13. Synthesis and characterization of calcium-alumino-silicate hydrates from oil shale ash - Towards industrial applications

    Energy Technology Data Exchange (ETDEWEB)

    Janek Reinik; Ivo Heinmaa; Jyri-Pekka Mikkola; Uuve Kirso [National Institute of Chemical Physics and Biophysics, Tallinn (Estonia)

    2008-08-15

    The influence of the alkaline medium on the hydrothermal activation of the oil shale fly ash with NaOH and KOH was studied using SEM/EDX, XRD, {sup 29}Si and {sup 27}Al high-resolution MAS-NMR spectra. In the presence of NaOH the silicon in the original fly ash was completely converted into calcium-aluminum-silicate-hydrates, mainly into 1.1 nm tobermorite structure during 24-h treatment at 160{sup o}C. At similar reaction conditions, the activation with KOH resulted only to the formation of amorphous calcium-silica-hydrate gel on the surface of ash particles at temperature. The results obtained in this study indicate that the oil shale fly ash can be used for production of Al-substituted tobermorites when strongly alkaline media (NaOH) is applied. The synthesized product was used in a catalytic d-lactose isomerization reaction. 29 refs., 7 figs., 2 tabs.

  14. Apatite precipitation on a novel fast-setting calcium silicate cement containing fluoride

    Science.gov (United States)

    Ranjkesh, Bahram; Chevallier, Jacques; Salehi, Hamideh; Cuisinier, Frédéric; Isidor, Flemming; Løvschall, Henrik

    2016-01-01

    Abstract Aim: Calcium silicate cements are widely used in endodontics. Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in teeth crowns including cavity lining and cementation. Objective: To evaluate the surface apatite-forming ability of Protooth compositions as a function of fluoride content and immersion time in phosphate-buffered saline (PBS). Material and methods: Three cement compositions were tested: Protooth (3.5% fluoride and 10% radiocontrast), ultrafast Protooth (3.5% fluoride and 20% radiocontrast), and high fluoride Protooth (15% fluoride and 25% radiocontrast). Powders were cap-mixed with liquid, filled to the molds and immersed in PBS. Scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy were used to characterize the precipitations morphology and composition after 1, 7, 28, and 56 days. Apatite/belite Raman peak height indicated the apatite thickness. Results: Spherical calcium phosphate precipitations with acicular crystallites were formed after 1-day immersion in PBS and Raman spectra disclosed the phosphate band at 965 cm−1, supporting the apatite formation over Protooth compositions. The apatite deposition continued and more voluminous precipitations were observed after 56 days over the surface of all cements. Raman bands suggested the formation of β-type carbonated apatite over Protooth compositions. High fluoride Protooth showed the most compact deposition with significantly higher apatite/belite ratio compared to Protooth and ultrafast Protooth after 28 and 56 days. Conclusions: Calcium phosphate precipitations (apatite) were formed over Protooth compositions after immersion in PBS with increasing apatite formation as a function of time. High fluoride Protooth exhibited thicker apatite deposition. PMID:27335901

  15. Determining the rational technological parameters of heatresistant concrete produced with sodium silicate binder

    OpenAIRE

    Manturov Z.A.

    2012-01-01

    Heat-resistant concrete is one of the most effective refractory materials. Using such concrete reduces the time of construction by 3-4 times, it decreases the labor costs during the construction of thermal units by 2-3 times, increases the working life of the thermal unit and, therefore, reduces the costs of maintenance and major repairs.This paper deals with heat-resistant concrete based on a sodium-silicate composite binder, regarded as an alternative to refractory concrete based on liquid ...

  16. Influence of sodium silicate concentration on structural and tribological properties of microarc oxidation coatings on 2017A aluminum alloy substrate

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Aytekin, E-mail: apolat@nigde.edu.t [Department of Mechanical Engineering, Nigde University, Nigde 51100 (Turkey); Makaraci, Murat [Department of Mechanical Engineering, Kocaeli University, Kocaeli (Turkey); Usta, Metin [Department of Materials Science and Engineering, Gebze Institute of Technology, Kocaeli (Turkey)

    2010-08-20

    In this paper, thick and hard oxide coatings resistant to wear were produced on 2017A-T6 Al alloy by the microarc oxidation (MAO) technique in an alkali electrolyte consisting of different sodium silicate concentrations (0-8 g/l). The coatings were characterized by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometry. Microhardness, scratch adhesion and pin-on-disk sliding wear tests were also performed to evaluate the tribological properties of the coatings. The influence of sodium silicate concentration on the structural and tribological properties of the MAO coatings was discussed. Results reveal that increasing sodium silicate concentration from 0 to 8 g/l in the electrolyte caused an increase in the electrolyte conductivity (from 7.71 to 18.1 mS/cm) and a decrease in positive final voltage (from 627 to 590 V) in the MAO process. In response to the increase in sodium silicate concentration, the thickness, surface roughness (R{sub a}) and critical load (L{sub c}) corresponding to adhesive failure of the coatings were increased simultaneously from 74 to 144 {mu}m, and 4.4 to 6.58 {mu}m, and 127.76 to 198.54 N, respectively. At the same time, the phase structure and composition of the coatings also varied by the participation of silicate ions in the reactions and their incorporation into the coating structure. Moreover, it was observed that the coating formed in the low sodium silicate concentration (4 g/l) had higher surface hardness (2020 HV) and improved wear resistance than the one (1800 HV) formed in the high sodium silicate concentration (8 g/l). The coatings produced in three different electrolytic solutions provided an excellent wear resistance and a load carrying capacity compared to the uncoated aluminum alloy.

  17. Bond strength of a calcium silicate-based sealer tested in bulk or with different main core materials

    OpenAIRE

    Nagas, Emre; Cehreli, Zafer; Mehmet Ozgur UYANIK; Veli DURMAZ

    2014-01-01

    The aim of this study was to evaluate the influence of a calcium silicate-based sealer (iRoot SP), with or without a core material, on bond strength to radicular dentin, in comparison with various contemporary root filling systems. Root canals of freshly extracted single-rooted teeth (n = 60) were instrumented using rotary instruments. The roots were randomly assigned to one of the following experimental groups: (1) a calcium silicate-based sealer without a core material (bulk-fill); (2) a ca...

  18. Insight into sodium silicate glass structural organization by multinuclear NMR combined with first-principles calculations

    International Nuclear Information System (INIS)

    Short and medium range order of silica and sodium silicate glasses have been investigated from a quantitative analysis of 29Si MAS NMR and 23Na, 17O MQMAS NMR spectra. The method described enables the extraction of the underlying 17O NMR parameter distributions of bridging oxygens (BOs) and non-bridging oxygens (NBOs), and yields site populations which are confirmed by 29Si NMR data. The extracted NMR parameter distributions and their variations with respect to the glass chemical composition can then be analyzed in terms of local structural features (bond angles and bond lengths, coordination numbers) with the help of molecular dynamics simulations combined with first-principles calculations of NMR parameters. Correlations of relevant structural parameters with 23Na, 29Si and 17O NMR interactions (isotropic chemical shift δ(iso), quadrupolar coupling constant C(Q) and quadrupolar asymmetry parameter ηQ are re-examined and their applicability is discussed. These data offer better insights into the structural organization of the glass network, including both chemical and topological disorder. Adding sodium to pure silica significantly diminishes the Si-O-Si bond angles and leads to a longer mean Si-O bond length with a slight decrease of the mean Na-O bond length. Moreover, the present data are in favor of a homogeneous distribution of Na around both oxygen species in the silicate network. Finally, our approach was found to be sensitive enough to investigate the effect of addition of a small quantity of molybdenum oxide (about 1 mol%) on the 17O MAS spectrum, opening new possibilities for investigating the Mo environment in silicate glasses. (authors)

  19. 21 CFR 573.280 - Feed-grade calcium stearate and sodium stearate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Feed-grade calcium stearate and sodium stearate... SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.280 Feed-grade calcium stearate and sodium...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-06-01

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

  1. Quantitative kinetic and structural analysis of geopolymers. Part 2. Thermodynamics of sodium silicate activation of metakaolin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zuhua, E-mail: zuhua.zhang2@usq.edu.au [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350 (Australia); Provis, John L. [Department of Materials Science and Engineering, The University of Sheffield, Mappin St, Sheffield S1 3JD (United Kingdom); Wang, Hao; Bullen, Frank [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350 (Australia); Reid, Andrew [Halok Pty Ltd. West End, QLD 4101 (Australia)

    2013-08-10

    Highlights: • ICC is confirmed again to be useful in studying the thermodynamics of geopolymerization. • Na-silicate activation of metakaolin at 25 °C processes an extent of ∼0.20, far from the final structure. • Na/Al has a more pronounced influence on the reaction extent of metakaolin than do temperature and Si/Al ratio. • ICC is expected to be a powerful technique in quantifying the reactivity of various aluminosilicate precursors. - Abstract: The paper describes the outcomes of a study using isothermal conduction calorimetry (ICC) to characterize the geopolymerization kinetics of metakaolin activated with sodium silicate. Two exothermic peaks are observed in the calorimetric curves for all systems reacting within the temperature range 20–40 °C. The peaks are assigned to the dissolution of metakaolin, and the formation of geopolymeric gels with disordered structure, respectively. Compared with the use of NaOH solution to activate metakaolin, the presence of soluble silicate in the activator hinders the reorganization of the local structure of geopolymeric gels and also suppresses the formation of zeolites or zeolite precursors. The ICC data are used via a thermochemical model to quantify the reaction kinetics of geopolymerization, by assuming that the geopolymeric gels have an analcime-like local structure and taking into account the speciation of the silicate monomers and dimers in the activator. Decreasing the modulus from 1.6 to 1.0 increases the fractional reaction extent from 0.12 to 0.26 after 72 h at 25 °C. When the modulus is 1.2, increasing the reaction temperature from 20 °C to 35 °C results in an improved reaction extent from 0.24 to 0.35. The rapid polymerization that occurs at 40 °C appears to hinder the further reaction of MK and consequently results in a lower reaction extent than at 35 °C. Combined with the findings from previous analysis of systems where NaOH was used to activate MK, the concentration of available Na

  2. Fluorescent properties of a green- to red-emitting Eu3+, Tb3+ codoped amorphous calcium silicate phosphor

    International Nuclear Information System (INIS)

    A Eu3+, Tb3+ codoped amorphous calcium silicate phosphor was prepared by heating a Eu3+, Tb3+ codoped calcium silicate hydrate phosphor formed by liquid-phase reaction for 30 min at 900 °C. The excitation peak wavelength of the resulting phosphor was 379 nm and the emission peak wavelengths were at 542 nm, attributed to the 5D4→7F5 transition of Tb3+, and at 613 mm, attributed to the 5D0→7F1 transition of Eu3+. The intensity ratio of the two peaks could be freely controlled by varying the Eu/Tb atomic ratio of the Eu3+, Tb3+ codoped amorphous calcium silicate phosphor, allowing light to be emitted over a wide range from green to red. It was clarified that electron transfer from Tb3+ to Eu3+ is occurring. - Highlights: ► A Eu3+, Tb3+ codoped CSH phosphor was synthesized by liquid-phase reaction. ► CSH phosphor was heated at 900 °C to obtain Eu3+, Tb3+ codoped amorphous calcium silicate phosphor. ► Under 379 nm excitation, this phosphor showed emission peaks at 542 nm and 613 nm. ► The luminescent color could be continuously changed from green to red with increasing Eu/Tb atomic ratio. ► It was clarified that electron transfer from Tb3+ to Eu3+ is occurring.

  3. A chemical activity evaluation of two dental calcium silicate-based materials

    Directory of Open Access Journals (Sweden)

    Chalas Renata

    2015-06-01

    Full Text Available Calcium silicate-based materials are interesting products widely used in dentistry. The study was designed to compare the chemical reaction between analyzed two preparates and dentin during cavity lining. In our work, dentinal discs were prepared from human extracted teeth filled with Biodentine and MTA+. The samples were then analyzed by way of SEM, EDS and Raman spectroscopy. The obtained results revealed differences in elemental composition between both materials. Biodentine showed higher activity in contact with dentine. Moreover, the interfacial layer in the tooth filled by Biodentine was wider than that in the tooth filled with MTA+. The applied methods of analysis confirmed that both materials have a bioactive potential which is a promising ability.

  4. Influence of Hydrothermal Temperature on Phosphorus Recovery Efficiency of Porous Calcium Silicate Hydrate

    Directory of Open Access Journals (Sweden)

    Wei Guan

    2013-01-01

    Full Text Available Porous calcium silicate hydrate (PCSH was synthesized by carbide residue and white carbon black. The influence of hydrothermal temperature on phosphorus recovery efficiency was investigated by Field Emission Scanning Electron Microscopy (FESEM, Brunauer-Emmett-Teller (BET, and X-Ray Diffraction (XRD. Hydrothermal temperature exerted significant influence on phosphorus recovery performance of PCSH. Hydrothermal temperature 170°C for PCSH was more proper to recover phosphorus. PCSH could recover phosphorus with content of 18.51%. The law of Ca2+ and OH− release was the key of phosphorus recovery efficiency, and this law depended upon the microstructure of PCSH. When the temperature of synthesis reached to 170°C, the reactions between CaO and amorphous SiO2 were more efficient. Solubility of SiO2 was a limiting factor.

  5. Study of caesium adsorption on hydrated calcium-silicate-aluminate systems

    International Nuclear Information System (INIS)

    Immobilization of caesium in cementitious matrixes was studied in the present paper which is a key issue of handling radioactive caesium containig wastes for caesium does not form stabile compounds therefor it can not be readily immobilized. Model matrices were prepared to map up the calcium-silicate-aluminate system considering caesium immobilization, which were of different starting compositions. To caracterize Cs sorption, distribution ratios were determined. Based on the results obtained the model matrix compositions were prepared using industrial grade materials and their caesium retardation and trapping were examined by means of leaching and sorption experiments. In the light of the results obtained, it can be established that immobilization of caesium significantly depend on the starting composition of the used matrix. (orig.)

  6. Influence of Hydrothermal Temperature on Phosphorus Recovery Efficiency of Porous Calcium Silicate Hydrate

    International Nuclear Information System (INIS)

    Porous calcium silicate hydrate (PCSH) was synthesized by carbide residue and white carbon black. The influence of hydrothermal temperature on phosphorus recovery efficiency was investigated by Field Emission Scanning Electron Microscopy (FESEM), Brunauer-Emmett-Teller (BET), and X-Ray Diffraction (XRD). Hydrothermal temperature exerted significant influence on phosphorus recovery performance of PCSH. Hydrothermal temperature 170°C for PCSH was more proper to recover phosphorus. PCSH could recover phosphorus with content of 18.51%. The law of Ca2+ and OH− release was the key of phosphorus recovery efficiency, and this law depended upon the microstructure of PCSH. When the temperature of synthesis reached to 170°C, the reactions between CaO and amorphous SiO2 were more efficient. Solubility of SiO2 was a limiting factor.

  7. Optical properties and Judd–Ofelt analysis of Eu3+ activated calcium silicate

    International Nuclear Information System (INIS)

    Eu3+ activated calcium silicate was synthesized in stoichiometric ratio using the co-precipitation technique. The phosphors were characterized using X-ray diffraction and photoluminescence technique. Based on Judd–Ofelt (J–O) analysis, the intensity parameters Ω2 and Ω4 were calculated from the emission spectra for various Europium concentrations. The determined values indicate higher hypersensitive behavior of the 5D0→7F2 transition of Eu3+ ions in the host matrix and a stronger covalency. Different radiative properties have been discussed as the function of Eu3+ concentration. The lifetime decay pattern recorded for these samples indicated single exponential behavior. The quantum efficiency has been calculated to be 62% from the emission spectrum and the fluorescence lifetime was found to be 2.9 ms

  8. Thermal conductivity of the gadolinium calcium silicate apatites: Effect of different point defect types

    International Nuclear Information System (INIS)

    The apatite crystal structure of the gadolinium calcium silicates can accommodate a wide range of point defects, including oxygen and cation vacancies, as well as anti-site defects, depending on the Gd/Ca ratio. Compositions having only cation or oxygen vacancies were identified and the thermal diffusivity and conductivity were measured up to 1000 deg. C. All the compositions, including the stoichiometric composition, exhibit low thermal conductivities from room temperature to high temperature with the defect-containing compositions having even lower thermal conductivities. The high-temperature thermal conductivity, at temperatures below the onset of significant radiative heat transport, decreases with the inverse square root of the cation and anion vacancy concentration, consistent with simple defect scattering models. Based on the data, it is concluded that the oxygen vacancies are slightly more effective in reducing thermal conductivity.

  9. Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu3+) as a drug carrier.

    Science.gov (United States)

    Fan, Yong; Huang, Shanshan; Jiang, Jinhua; Li, Guogang; Yang, Piaoping; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2011-05-15

    Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu) was successfully synthesized. The obtained MCS: Eu(3+) was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as the model drug. The structural, morphological, textural, and optical properties were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption/desorption, and photoluminescence (PL) spectra, respectively. The results reveal that the MCS: Eu exhibits the typical ordered characteristics of the mesostructure. This composite shows a sustained release profile with IBU as the model drug. The IBU-loaded samples still present red luminescence of Eu(3+) ((5)D(0)-(7)F(1,2)) under UV irradiation. The emission intensities of Eu(3+) in the drug carrier system vary with the amount of released IBU, making the drug release easily tracked and monitored. The system demonstrates a great potential for drug delivery and disease therapy. PMID:21376337

  10. Optical properties and Judd–Ofelt analysis of Eu{sup 3+} activated calcium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Barve, R.A., E-mail: rujuta_barve2003@yahoo.com; Suriyamurthy, N.; Panigrahi, B.S.; Venkatraman, B.

    2015-10-15

    Eu{sup 3+} activated calcium silicate was synthesized in stoichiometric ratio using the co-precipitation technique. The phosphors were characterized using X-ray diffraction and photoluminescence technique. Based on Judd–Ofelt (J–O) analysis, the intensity parameters Ω{sub 2} and Ω{sub 4} were calculated from the emission spectra for various Europium concentrations. The determined values indicate higher hypersensitive behavior of the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition of Eu{sup 3+} ions in the host matrix and a stronger covalency. Different radiative properties have been discussed as the function of Eu{sup 3+} concentration. The lifetime decay pattern recorded for these samples indicated single exponential behavior. The quantum efficiency has been calculated to be 62% from the emission spectrum and the fluorescence lifetime was found to be 2.9 ms.

  11. Distinctive microstructural features of aged sodium silicate-activated slag concretes

    Energy Technology Data Exchange (ETDEWEB)

    San Nicolas, Rackel [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Bernal, Susan A. [Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD (United Kingdom); School of Materials Engineering, Composite Materials Group, Universidad del Valle, Cali (Colombia); Mejía de Gutiérrez, Ruby [School of Materials Engineering, Composite Materials Group, Universidad del Valle, Cali (Colombia); Deventer, Jannie S.J. van [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012 (Australia); Provis, John L., E-mail: j.provis@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin St, Sheffield S1 3JD (United Kingdom)

    2014-11-15

    Electron microscopic characterisation of 7-year old alkali-activated blast-furnace slag concretes enabled the identification of distinct microstructural features, providing insight into the mechanisms by which these materials evolve over time. Backscattered electron images show the formation of Liesegang-type ring formations, suggesting that the reaction at advanced age is likely to follow an Oswald supersaturation–nucleation–depletion cycle. Segregation of Ca-rich veins, related to the formation of Ca(OH){sub 2}, is observed in microcracked regions due to the ongoing reaction between the pore solution and available calcium from remnant slag grains. A highly dense and uniform interfacial transition zone is identified between siliceous aggregate particles and the alkali activated slag binders, across the concretes assessed. Alkali-activated slag concretes retain a highly dense and stable microstructure at advanced ages, where any microcracks induced at early ages seem to be partially closing, and the remnant slag grains continue reacting.

  12. In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Yinfu; Huang, Yanlin; Qi, Shuyun [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Chen, Cuili [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-10-01

    A novel calcium silicate borate Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics were also measured, which indicate that the biomaterials based on Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si–OH) and B–OH groups can be easily induced on the surface of Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics soaked in SBF solutions. - Highlights: • Calcium silicate borate Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} ceramics were developed as a new biomaterial. • Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} shows a superior in vitro bioactivity by inducing bone-like apatite. • Ca{sub 11}Si{sub 4}B{sub 2}O{sub 22} has good mechanical properties as potential candidate biomaterials. • The structure with SiO{sub 4} and BO{sub 3} groups is favorable for hydroxyapatite formation.

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

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiu-lan; Saigusa Masaihiko

    2007-01-01

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

  14. In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics

    International Nuclear Information System (INIS)

    A novel calcium silicate borate Ca11Si4B2O22 ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca11Si4B2O22 ceramics were also measured, which indicate that the biomaterials based on Ca11Si4B2O22 ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si–OH) and B–OH groups can be easily induced on the surface of Ca11Si4B2O22 ceramics soaked in SBF solutions. - Highlights: • Calcium silicate borate Ca11Si4B2O22 ceramics were developed as a new biomaterial. • Ca11Si4B2O22 shows a superior in vitro bioactivity by inducing bone-like apatite. • Ca11Si4B2O22 has good mechanical properties as potential candidate biomaterials. • The structure with SiO4 and BO3 groups is favorable for hydroxyapatite formation

  15. Determination of Iron in Layered Crystal Sodium Disilicate and Sodium Silicate by Flame Atomic Absorption Spectrometry with Boric Acid as a Matrix Modifier

    Institute of Scientific and Technical Information of China (English)

    Zhi Hua WANG; Min CAI; Shu Jun WANG

    2006-01-01

    The effects of matrix silicate and experimental conditions on the determination of iron in flame atomic absorption spectrometry (FAAS) were investigated. It was found that boric acid as a matrix modifier obviously eliminated silicate interference. Under the optimum operating conditions, the determination results of iron in layered crystal sodium disilicate and sodium silicate samples by FAAS were satisfactory. The linear range of calibration curve is 0-10.5 μg.mL-1, the relative standard deviation of method is 1.2%-2.2%, the recovery of added iron is 96.0%-101%, the of iron of the standard curve method, standard addition calibration and colorimetry method was the same, but the first has the merits of rapid sample preparation, reduced contamination risks and fast analysis.

  16. The effect of electron beam irradiation on silver-sodium ion exchange in silicate glasses

    Science.gov (United States)

    Sidorov, Alexander I.; Prosnikov, Mikhail A.

    2016-04-01

    It is shown experimentally that electron irradiation of sodium-silicate glasses makes possible the control of the subsequent ion exchange Ag+ ↔ Na+ process in a salt melt. The reason of this effect is the negatively charged regions formation in a glass volume during electron irradiation. The electric field, produced by these regions in glass volume, results in positive Na+ ions field migration into them. The spatial redistribution of Na+ ions results in the decrease of the ion exchange efficiency, or the ion exchange can be even blocked. This led to the decrease of the luminescence intensity of neutral silver molecular clusters in the irradiated zone, and effect on the silver nanoparticles formation during the subsequent thermal treatment. The observed effects can be used for the control of ion exchange processes during integrated optics devices fabrication, and for the electron-beam recording of optical information.

  17. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A., E-mail: ivan_melendez380@hotmail.com [Centro de Investigacion en Quimica Aplicada, Bldv. Enrique Reyna Hermosillo No. 140, Saltillo 25294, Coahuila (Mexico)

    2013-08-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na{sub 2}SiO{sub 3}) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO{sub 2} molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO{sub 2} molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  18. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    International Nuclear Information System (INIS)

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na2SiO3) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  19. Hydrothermal Synthesis of SBA-15 Using Sodium Silicate Derived from Coal Gangue

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2013-01-01

    Full Text Available Well-ordered SBA-15 was prepared with a hydrothermal route by sodium silicate derived from coal gangue. The as-prepared sample was analyzed by SAXRD, BET, TEM, and SEM, respectively. The results indicate that at a low hydrothermal temperature of 100∘C the well-ordered mesoporous SBA-15 could be synthesized. The surface area, pore volume, and pore size of the sample are 552 m2/g, 0.54 cm3/g, and 7.0 nm, respectively. It is suggested that coal gangue could be used in obtaining an Si source to prepare mesoporous materials, such as SBA-15.

  20. Experimental Evaluation of Sodium Silicate-Based Nanosilica against Chloride Effects in Offshore Concrete

    Directory of Open Access Journals (Sweden)

    Kyoung-Min Kim

    2014-01-01

    Full Text Available This study investigates the effect of a new pore filling material, named sodium silicate-based nanosilica (SS, on resisting the diffusion of the chloride ions. The proposed SS is chosen, mainly due to its smaller particle size, compared to the conventional ethyl silicate-based nanosilica. Each particle of SS is chemically treated to have the negative (− charge on its surface. Four types of mixes with different amounts of partial replacement with fly ash and slag are prepared. Effect of water to binder ratios (0.35, 0.40, and 0.45 is also examined. Test results showed that the inclusion of SS was significantly beneficial for protecting the concrete from chloride attack. At a given strength, the SS inclusion in concrete was up to three times more effective than the control concrete without SS. It is believed that these excellent results are attributed to the small particle size and the chemical surface treatment of SS. In this study, experiments of compressive strength, hydration heat, accelerated neutralization, and sulfate erosion tests were also conducted to find the general effect of SS inclusion on the fundamental properties and durability of concrete.

  1. A Comprehensive Study of Osteogenic Calcium Phosphate Silicate Cement: Material Characterization and In Vitro/In Vivo Testing.

    Science.gov (United States)

    Gong, Tianxing; Wang, Zhiqin; Zhang, Yixi; Zhang, Yubiao; Hou, Mingxiao; Liu, Xinwei; Wang, Yu; Zhao, Lejun; Ruse, N Dorin; Troczynski, Tom; Häfeli, Urs O

    2016-02-18

    Vertebral compression fractures can be successfully restored by injectable bone cements. Here the as-yet unexplored in vitro cytotoxicity, in vivo biodegradation, and osteoconductivity of a new calcium phosphate silicate cements (CPSC) are studied, where monocalcium phosphate (MCP; 5, 10, and 15 wt%) is added to calcium silicate cement (CSC). Setting rate and compressive strength of CPSC decrease with the addition of MCP. The crystallinity, microstructure, and porosity of hardened CPSC are evaluated by X-ray diffractometer, Fourier transform infrared spectroscopy, and microcomputed tomography (CT). It is found that MCP reacts with calcium hydroxide, one of CSC hydration products, to precipitate apatite. While the reaction accelerates the hydration of CSC, the formation of calcium silicate hydrate gel is disturbed and highly porous microstructures form, resulting in weaker compressive strength. In vitro studies demonstrate that CPSC is noncytotoxic to osteoblast cells and promotes their proliferation. In the rabbit tibia implantation model, clinical X-ray and CT scans demonstrate that CPSC biodegrades slower and osseointegrates better than clinically used calcium phosphate cement (CPC). Histological studies demonstrate that CPSC is osteoconductive and induces higher bone formation than CPC, a finding that might warrant future clinical studies. PMID:26677175

  2. Effect of drying technique on the physicochemical properties of sodium silicate-based mesoporous precipitated silica

    International Nuclear Information System (INIS)

    The conventional drying (oven drying) method used for the preparation of precipitated mesoporous silica with low surface area (>300 m2/g) and small pore volume is often associated with a high production cost and a time consuming process. Therefore, the main goal of this study was to develop a cost-effective and fast drying process for the production of precipitated mesoporous silica using inexpensive industrial grade sodium silicate and spray drying of the precipitated wet-gel silica slurry. The precipitated wet-gel silica slurry was prepared from an aqueous sodium silicate solution through the drop-wise addition of sulfuric acid. Mesoporous precipitated silica powder was prepared by drying the wet-gel slurry with different drying techniques. The effects of the oven drying (OD), microwave drying (MD), and spray drying (SD) techniques on the physical (oil, water absorption, and tapping density), and textural properties (specific BET surface area, pore volume, pore size, and % porosity) of the precipitated mesoporous silica powder were studied. The dried precipitated mesoporous silica powders were characterized with field-emission scanning electron microscopy; Brunauer, Emmett and Teller and BJH nitrogen gas adsorption/desorption methods; Fourier-transform infrared spectroscopy; thermogravimetric and differential analysis; N2 physisorption isotherm; pore size distribution and particle size analysis. There was a significant effect of drying technique on the textural properties, such as specific surface area, pore size distribution and cumulative pore volume of the mesoporous silica powder. Additionally, the effect of the microwave-drying period on the physicochemical properties of the precipitated mesoporous silica powder was investigated and discussed.

  3. Push-out bond strength of CPP-ACP-modified calcium silicate-based cements.

    Science.gov (United States)

    Dawood, Alaa E; Manton, David J; Parashos, Peter; Wong, Rebecca H k; Palamara, Joseph E A; Reynolds, Eric C

    2015-01-01

    This study evaluated the push-out bond strength of 0%, 0.5%, 1.0%, 2.0% and 3.0% (w/w) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified calcium silicate-based cements (CSCs). The push-out bond strength of a trial MTA was also compared with two CSCs (Biodentine(™) and Angelus(®) MTA). Three hundred 1 mm thick horizontal root sections were prepared from 60 singlerooted human teeth. The canal space of each section was enlarged and filled with the cements. The sections were stored in a phosphate buffer solution. After incubation for 2 months, the push-out bond strength was measured and the data were analyzed using one way analysis of variance followed by Tukey's test. The addition of CPP-ACP to the test cements increased the push-out bond strength (p<0.05). The push-out bond strength of Biodentine(™) was higher than the other cements (p<0.05). There was no statistically significant difference between Angelus(®) MTA and the trial MTA with most of CPP-ACP concentrations. PMID:26235714

  4. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials.

    Science.gov (United States)

    Küçükkaya, Selen; Görduysus, Mehmet Ömer; Zeybek, Naciye Dilara; Müftüoğlu, Sevda Fatma

    2016-01-01

    The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM) cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P > 0.05). MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P Biodentine showed significantly less cell viability (73%) after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P Biodentine and CEM can be considered as alternative materials for root-end surgery procedures. PMID:26904364

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

    International Nuclear Information System (INIS)

    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 as foaming agent resulting on the formation of porous 3D structures. After aging for 28 days, these porous inorganic scaffolds were immersed in calcium chloride supersaturated solution in PBS for 7 days at 37 deg. C for the biomimetic layer deposition. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier Transformed Infrared Spectroscopy (FTIR) techniques were used in order to characterize the porous scaffolds and the apatite-like biomimetic coating. The results have showed that 3D constructs were successfully produced with interconnected porosity, compressive strength and cytocompatibility appropriate for potential use as an alternative in trabecular bone repair.

  6. Physical characteristics, antimicrobial and odontogenesis potentials of calcium silicate cement containing hinokitiol.

    Science.gov (United States)

    Huang, Ming-Hsien; Shen, Yu-Fang; Hsu, Tuan-Ti; Huang, Tsui-Hsien; Shie, Ming-You

    2016-08-01

    Hinokitiol is a natural material and it has antibacterial and anti-inflammatory effects. The purpose of this study was to evaluate the material characterization, cell viability, antibacterial and anti-inflammatory abilities of the hinokitiol-modified calcium silicate (CS) cement as a root end filling material. The setting times, diametral tensile strength (DTS) values and XRD patterns of CS cements with 0-10mM hinokitiol were examined. Then, the antibacterial effect and the expression levels of cyclooxygenase 2 (COX-2) and interleukin-1 (IL-1) of the hinokitiol-modified CS cements were evaluated. Furthermore, the cytocompatibility, the expression levels of the markers of odontoblastic differentiation, mineralized nodule formation and calcium deposition of human dental pulp cells (hDPCs) cultured on hinokitiol-modified CS cements were determined. The hinokitiol-modified CS cements had better antibacterial and anti-inflammatory abilities and cytocompatibility than non-modified CS cements. Otherwise, the hinokitiol-modified CS cements had suitable setting times and better odontoblastic potential of hDPCs. Previous report pointed out that the root-end filling materials may induce inflammatory cytokines reaction. In our study, hinokitiol-modified CS cements not only inhibited the expression level of inflammatory cytokines, but also had better cytocompatibility, antimicrobial properties and active ability of odontoblastic differentiation of hDPCs. Therefore, the hinokitiol-modified CS cement may be a potential root end filling material for clinic. PMID:27157721

  7. Nanostructural Deformation Analysis of Calcium Silicate Hydrate in Portland Cement Paste by Atomic Pair Distribution Function

    Directory of Open Access Journals (Sweden)

    Hiroshi Suzuki

    2016-01-01

    Full Text Available The deformation of nanostructure of calcium silicate hydrate (C-S-H in Portland cement (PC paste under compression was characterized by the atomic pair distribution function (PDF, measured using synchrotron X-ray diffraction. The PDF of the PC paste exhibited a unique deformation behavior for a short-range order below 2.0 nm, close to the size of the C-S-H globule, while the deformation for a long-range order was similar to that of a calcium hydroxide phase measured by Bragg peak shift. The compressive deformation of the C-S-H nanostructure was comprised of three stages with different interactions between globules. This behavior would originate from the granular nature of C-S-H, which deforms with increasing packing density by slipping the interfaces between globules, rearranging the overall C-S-H nanostructure. This new approach will lead to increasing applications of the PDF technique to understand the deformation mechanism of C-S-H in PC-based materials.

  8. Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

    International Nuclear Information System (INIS)

    There exists limited information regarding the effect of temperature on the structure and solubility of calcium aluminosilicate hydrate (C–A–S–H). Here, calcium (alumino)silicate hydrate (C–(A–)S–H) is synthesised at Ca/Si = 1, Al/Si ≤ 0.15 and equilibrated at 7–80 °C. These systems increase in phase-purity, long-range order, and degree of polymerisation of C–(A–)S–H chains at higher temperatures; the most highly polymerised, crystalline and cross-linked C–(A–)S–H product is formed at Al/Si = 0.1 and 80 °C. Solubility products for C–(A–)S–H were calculated via determination of the solid-phase compositions and measurements of the concentrations of dissolved species in contact with the solid products, and show that the solubilities of C–(A–)S–H change slightly, within the experimental uncertainty, as a function of Al/Si ratio and temperature between 7 °C and 80 °C. These results are important in the development of thermodynamic models for C–(A–)S–H to enable accurate thermodynamic modelling of cement-based materials

  9. Mechanistic study and modeling of radionuclides retention by the hydrated calcium silicates (HCS) of cements

    International Nuclear Information System (INIS)

    This work attempts to investigate the modelling of radioisotopes (Cs+, Pb2+, Eu3+) immobilization in cement matrix, in the frame of the design of engineered barrier of a deep radwaste repository. The model development concept consists of three major steps: - surface chemistry modelling of the calcium silicate hydrate CSH, used to simulate hydrated cement behaviour; - solid analysis of the batch sorption experiments: identification of the uptake mechanism; - both previous steps are used, with isotherm data, in the modelling of the radioisotopes immobilization in the CSH matrix. Final results: (all modelling are available for all the range of studied Ca/Si ratios and have been validated with predictive calculations). - A thermodynamic modelling of the CSH surface chemistry has been developed. The labile calcium and proton sorption constants on silanol sites (>SiOH) have been extracted. - Cs+ is sorbed on two sites. The silanol site (weak site) has a high site density (10 sites.nm-2), which accounts for the CSH unsaturation in high [CS+]. A strong site is also identified. - Pb2+ immobilization in CSH matrix is modelled with surface equilibria and solubility equilibrium. - Eu3+ fixation has been investigated with solid analysis: Site-Selective anti Time-Resolved Luminescence Spectroscopy, XPS and SEM-EDS. Eu3+ thus does not precipitate in CSH water but is sorbed on the CSH surface (high hydroxylated environment). Europium is also (minority site) inserted in the CSH framework. (author)

  10. Development of a novel fluorapatite-forming calcium phosphate cement with calcium silicate: in vitro and in vivo characteristics.

    Science.gov (United States)

    Suzuki, Yusuke; Hayashi, Makoto; Yasukawa, Takuya; Kobayashi, Hiroshi; Makino, Kosuke; Hirano, Yoriyuki; Takagi, Shozo; Chow, Laurence C; Ogiso, Bunnai

    2015-01-01

    Aim of this study was to develop a novel fluorapatite-forming calcium phosphate cement (FA-CPC) with tricalcium silicate (TCS) for endodontic applications and to examine its in vitro and in vivo characteristics. The FA-CPC powder consisted of 62.8% CaHPO4, 30.8% CaCO3, and 6.4% NaF. One part of TCS was combined with 9 parts of FA-CPC powder (FA-CPC with TCS). A 1.5 M phosphate solution was used as cement liquid. Setting time (ST), diametral tensile strength (DTS), phase composition by X-ray diffraction (XRD), and cement alkalinity were analyzed. Cement biocompatibility was assessed using rat subcutaneous model. Cement ST was 10.3±0.6 min and DTS was 3.89±0.76 MPa. XRD patterns showed that highly crystalline apatitic material was the only significant phase present and pH value was approximate 11.0. FA-CPC with TCS demonstrated similar biocompatibility as that of mineral trioxide aggregate control. These results suggest that FA-CPC with TCS may be useful for endodontic applications. PMID:25740309

  11. Apatite formation on bioactive calcium-silicate cements for dentistry affects surface topography and human marrow stromal cells proliferation.

    Science.gov (United States)

    Gandolfi, Maria Giovanna; Ciapetti, Gabriela; Taddei, Paola; Perut, Francesca; Tinti, Anna; Cardoso, Marcio Vivan; Van Meerbeek, Bart; Prati, Carlo

    2010-10-01

    The effect of ageing in phosphate-containing solution of bioactive calcium-silicate cements on the chemistry, morphology and topography of the surface, as well as on in vitro human marrow stromal cells viability and proliferation was investigated. A calcium-silicate cement (wTC) mainly based on dicalcium-silicate and tricalcium-silicate was prepared. Alpha-TCP was added to wTC to obtain wTC-TCP. Bismuth oxide was inserted in wTC to prepare a radiopaque cement (wTC-Bi). A commercial calcium-silicate cement (ProRoot MTA) was tested as control. Cement disks were aged in DPBS for 5 h ('fresh samples'), 14 and 28 days, and analyzed by ESEM/EDX, SEM/EDX, ATR-FTIR, micro-Raman techniques and scanning white-light interferometry. Proliferation, LDH release, ALP activity and collagen production of human marrow stromal cells (MSC) seeded for 1-28 days on the cements were evaluated. Fresh samples exposed a surface mainly composed of calcium-silicate hydrates CSH (from the hydration of belite and alite), calcium hydroxide, calcium carbonate, and ettringite. Apatite nano-spherulites rapidly precipitated on cement surfaces within 5 h. On wTC-TCP the Ca-P deposits appeared thicker than on the other cements. Aged cements showed an irregular porous calcium-phosphate (Ca-P) coating, formed by aggregated apatite spherulites with interspersed calcite crystals. All the experimental cements exerted no acute toxicity in the cell assay system and allowed cell growth. Using biochemical results, the scores were: fresh cements>aged cements for cell proliferation and ALP activity (except for wTC-Bi), whereas fresh cements

  12. 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

    International Nuclear Information System (INIS)

    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.

  13. The dynamics of melts containing mobile ions: computer simulations of sodium silicates

    International Nuclear Information System (INIS)

    We present the results of large-scale computer simulations in order to discuss the structural and dynamic properties of sodium silicate melts with the compositions (Na2O)2(SiO2) (NS2) and (Na2O)20(SiO2) (NS20). We show that, compared to silica (SiO2), these systems exhibit additional intermediate range order on intermediate length scales that stem from the tetrahedral network structure. By means of intermediate-scattering functions, we characterize the dynamics of sodium in the system under consideration. Whereas in NS2 the incoherent scattering functions for Na decay much faster to zero than the coherent ones for Na-Na, in NS20 this different behaviour of the incoherent and coherent functions is not very pronounced. On the other hand, the incoherent functions of the two systems share a very peculiar feature: their long-time decay can be described by a Kohlrausch law with a constant exponent β for q > qth where qth is significantly below the location of the main peak in the static structure factor for the Na-Na correlations

  14. Fluorescence Properties and Synthesis of Green-Emitting Tb3+-Activated Amorphous Calcium Silicate Phosphor by Ultraviolet Irradiation of 378 nm

    OpenAIRE

    Yoshiyuki Kojima; Masaaki Numazawa; Shinnosuke Kamei; Nobuyuki Nishimiya

    2012-01-01

    The excitation wavelength of conventional Tb3+-activated phosphor is near 270 nm. This study describes novel green-emitting Tb3+-activated amorphous calcium silicate by ultraviolet excitation at 378 nm. The Tb3+-activated amorphous calcium silicate was prepared by heating a sample of Tb3+-activated calcium silicate hydrate (CSH) at 900°C for 30 minutes. The emission wavelength of the resulting phosphor was 544 nm. The optimum excitation wavelength within the range 300–400 nm was 378 nm. The T...

  15. Anticaries effect of dentifrices with calcium citrate and sodium trimetaphosphate

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Botazzo Delbem

    2012-02-01

    Full Text Available 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 µg 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 µg 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 (p0.05. CONCLUSIONS: Dentifrices with 450 and 1,000 µg F/g, Cacit and TMP were as effective as a gold standard one.

  16. Graphene-reinforced calcium silicate coatings for load-bearing implants

    International Nuclear Information System (INIS)

    Owing to the superior mechanical properties and low coefficient of thermal expansion, graphene has been widely used in the reinforcement of ceramics. In the present study, various ratios of graphene (0.5 wt%, 1.5 wt% and 4 wt%) were reinforced into calcium silicate (CS) coatings for load-bearing implant surface modification. Surface characteristics of the graphene/calcium silicate (GC) composite coatings were characterized by scanning electron microscopy. Results show that the graphene plates (less than 4 wt% in the coatings) were embedded in the CS matrix homogeneously. The surfaces of the coatings showed a hierarchical hybrid nano-/microstructure, which is believed to be beneficial to the behaviors of the cell and early bone fixation of the implants. Wear resistance measured by a pin-on-disc model exhibited an obvious enhancement with the adoption of graphene plates. The weight losses of the GC coatings decreased with the increase of graphene content. However, too high graphene content (4 wt% or more) made the composite coatings porous and the wear resistance decreased dramatically. The weight loss was only 1.3 ± 0.2 mg for the GC coating containing 1.5 wt% graphene (denoted as GC1.5) with a load of 10 N and sliding distance of 500 m, while that of the pure CS coating reached up to 28.6 ± 0.5 mg. In vitro cytocompatibility of the GC1.5 coating was evaluated using a human marrow stem cell (hMSC) culture system. The proliferation and alkaline phosphatase, osteopontin and osteocalcin (OC) osteogenesis-related gene expression of the cells on the GC1.5 coating did not deteriorate with the adoption of graphene. Conversely, even better adhesion of the hMSCs was observed on the GC1.5 coating than on the pure CS coating. All of the results indicate that the GC1.5 coating is a good candidate for load-bearing implants. (paper)

  17. Activity diagrams for calcium/hydrogen, sodium/hydrogen, and potassium/hydrogen, and H4SiO4 and their relation to reactions in systems containing radioactive waste forms, cement, and rock in the presence of water

    International Nuclear Information System (INIS)

    In order to identify reactions which can occur in systems containing nuclear waste forms, cement, and repository rock in the presence of water, activity diagrams were calculated from free energies for aluminosilicates and calcium silicates. Groundwater compositions from candidate repository sites in the Palo Duro Basin of Texas, the Delaware Basin of New Mexico, and the Nevada Test Site were plotted on these diagrams. Essentially all of these are shown to be in the calcium zeolite field as shown on the diagram for calcium in the absence of other cations. Chlorite is shown to be stable in this region at the Mg and pH level of the Ogallala if the chlorite is high in iron, and at the Mg and pH level of the Wolfcamp low- or high-Fe chlorites are stable. Potassium and sodium mineral relationships fall in two categories, dilute waters and saline waters. Boreholes at Yucca Flat and Mercury Valley at the Nevada Test Site, and shallow ground water from the Rolling Plains north and east of the Palo Duro Basin are in equilibrium with kaolinite. The brines from the Salado and Rustler formations are in equilibrium with kaolinite and possibly also with sodium-potassium zeolite and illite. Leachates of cement and water, and cement, waste, and water were plotted on the calcium silicate activity diagram. These solutions are in equilibrium with calcium silicate hydrate hydrolysis reactions, with grossular and possibly with Ca-zeolites. Among the calcium silicates, calcium-silicate-hydrate gel (C-S-H gel) and tobermorite are the most likely candidates, but the thermodynamic data are not adequate to distinguish all the possibilities. 37 references, 4 figures, 3 tables

  18. Co-production of biodiesel and hydrogen from rapeseed and Jatropha oils with sodium silicate and Ni catalysts

    International Nuclear Information System (INIS)

    Graphical abstract: Sodium silicate was an effective catalyst for the microwave-irradiated production of biodiesel and hydrothermal production of hydrogen from by-product glycerol combined with Ni catalyst. Highlights: ► Calcined sodium silicate was used for microwave-irradiated transesterification. ► Biodiesel yield of 95.8% was achieved from rapeseed oil at 400 W in 5 min. ► Biodiesel yield of 92.8% was achieved from Jatropha oil at 400 W in 5 min. ► The fourth cycled catalyst was utilized to gasify by-product glycerol at 350 °C. ► H2 yield of 82.8% (purity 73.6%) was achieved with the used and Ni catalysts. - Abstract: Calcined sodium silicate was used to rapidly catalyze the transesterification of rapeseed and Jatropha oils to biodiesel under microwave irradiation. Biodiesel yields of 95.8% and 92.8% were achieved from rapeseed and Jatropha oils, respectively (microwave power of 400 W, methanol/oil molar ratio of 11/1, catalyst amount of 4 wt.% and reaction time of 5 min). The catalyst was recycled, and biodiesel yield reduced to 83.6% at the fourth cycle. Fresh and reused sodium silicate catalysts were charaterized by BET (Brunauer, Emmett and Teller) surface area, XRD (X-ray diffraction), SEM (scanning electron microscope) and CO2-TPD (temperature programmed desorption), and it was found that the agglomeration and leaching of basic species resulted in the loss of catalytic activity. The reused catalyst was collected and utilized for hydrothermal gasification of glycerol to hydrogen. A maximum H2 yield of 82.8% with a concentration of 73.6% was obtained in the presence of the fourth-cycled sodium silicate and Ni catalysts at 350 °C. Sodium silicate was an effective catalyst for the microwave-irradiated production of biodiesel and hydrothermal production of hydrogen from by-product glycerol combined with Ni catalyst

  19. Preparation and in vitro evaluation of strontium-doped calcium silicate/gypsum bioactive bone cement

    International Nuclear Information System (INIS)

    The combination of two or more bioactive components with different biodegradability could cooperatively improve the physicochemical and biological performances of the biomaterials. Here we explore the use of α-calcium sulfate hemihydrate (α-CSH) and calcium silicate with and without strontium doping (Sr-CSi, CSi) to fabricate new bioactive cements with appropriate biodegradability as bone implants. The cements were fabricated by adding different amounts (0–35 wt%) of Sr-CSi (or CSi) into the α-CSH-based pastes at a liquid-to-solid ratio of 0.4. The addition of Sr-CSi into α-CSH cements not only led to a pH rise in the immersion medium, but also changed the surface reactivity of cements, making them more bioactive and therefore promoting apatite mineralization in simulated body fluid (SBF). The impact of additives on long-term in vitro degradation was evaluated by soaking the cements in Tris buffer, SBF, and α-minimal essential medium (α-MEM) for a period of five weeks. An addition of 20% Sr-CSi to α-CSH cement retarded the weight loss of the samples to 36% (in Tris buffer), 43% (in SBF) and 54% (in α-MEM) as compared with the pure α-CSH cement. However, the addition of CSi resulted in a slightly faster degradation in comparison with Sr-CSi in these media. Finally, the in vitro cell-ion dissolution products interaction study using human fetal osteoblast cells demonstrated that the addition of Sr-CSi improved cell viability and proliferation. These results indicate that tailorable bioactivity and biodegradation behavior can be achieved in gypsum cement by adding Sr-CSi, and such biocements will be of benefit for enhancing bone defect repair. (paper)

  20. Photo-luminescent properties of a green or red emitting Tb3+ or Eu3+ doped calcium magnesium silicate phosphors

    International Nuclear Information System (INIS)

    This study describes green-emitting Tb3+ or red-emitting Eu3+ doped calcium magnesium silicate phosphors by ultraviolet excitation at 335 nm. The rare earth activated amorphous calcium silicate was prepared by a solution–combustion process at 600 °C for 5–10 min. The Ca2MgSi2O7 prepared using urea and ammonium nitrate has a tetragonal crystal structure. The resulting Tb3+-doped phosphor emitted green light centered at 544 nm. The optimum excitation wavelength within the range 300–400 nm was 335 nm. The intensity and emitting wavelength of the Eu3+ doped samples can be controlled by annealing in a reducing or oxidizing environment, allowing light to be emitted as green or red. When the reducing environment is optimized, the emission spectrum of Ca2MgSi2O7:Eu2+ is a broad band at 497 nm.

  1. Biological Assessment of a Calcium Silicate Incorporated Hydroxyapatite-Gelatin Nanocomposite: A Comparison to Decellularized Bone Matrix

    OpenAIRE

    Dong Joon Lee; Ricardo Padilla; He Zhang; Wei-Shou Hu; Ching-Chang Ko

    2014-01-01

    Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS). Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD). Twelve Sprague-Dawley rats were randomized to four groups: control (defect only), decellularized bone matrix (DECBM), and HGCS with and without multipotent adult progenitor cells (MAPCs). DECBM was prepared by removing all the cells using ...

  2. Structural models of random packing of spheres extended to bricks. Simulation of the nanoporous Calcium-Silicate-Hydrates.

    OpenAIRE

    Morales-Florez, Victor; BRUNET, Fabrice

    2009-01-01

    Abstract Structure simulation algorithms of random packing of spheres and bricks have been developed. These algorithms were used to reproduce the nanostructure of the cementitius calcium-silicate-hydrates. The textural parameters (specific surface area, porosity, pore size, etc.) of a C-S-H sample, the main binding phase of cements, have been derived from N2-physisorption experiments. In the same time, these parameters have been simulated by using a sphere-based structural model wh...

  3. Effects of graphene plates’ adoption on the microstructure, mechanical properties, and in vivo biocompatibility of calcium silicate coating

    OpenAIRE

    Xie YT; Li HQ; Ding CX; Zheng XB; Li K

    2015-01-01

    Youtao Xie, Hongqin Li, Chuanxian Ding, Xuebin Zheng, Kai Li Shanghai Institute of Ceramics, Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences, Shanghai, People’s Republic of China Abstract: Calcium silicate (CS) ceramic is a good coating candidate for biomedical implants to improve biocompatibility and accelerate early osseo-integration. However, the poor fracture toughness and wear resistance of this ceramic material restricts the long-term performance of impl...

  4. Solubility of a new calcium silicate-based root-end filling material

    Directory of Open Access Journals (Sweden)

    Shishir Singh

    2015-01-01

    Full Text Available Introduction: The purpose of this study was to compare solubility of a new calcium silicate-based cement, Biodentine with three commonly used root-end filling materials viz. glass-ionomer cement (GIC, intermediate restorative material (IRM, and mineral trioxide aggregate (MTA. Materials and Methods: Twenty stainless steel ring molds were filled with cements corresponding to four groups (n = 5. The weight of 20 dried glass bottles was recorded. Samples were transferred to bottles containing 5 ml of distilled water and stored for 24 h. The bottles were dried at 105΀C and weighed. This procedure was repeated for 3, 10, 30, and 60 days. Data was analyzed with one-way analysis of variance (ANOVA test (P < 0.05. Results: Biodentine demonstrated significantly higher solubility than MTA for 30- and 60-day immersion periods. Statistical difference was noted between the solubility values of Biodentine samples amongst each of the five time intervals. Conclusions: Biodentine exhibited higher solubility in comparison with all other cements.

  5. A novel titania/calcium silicate hydrate hierarchical coating on titanium.

    Science.gov (United States)

    Huang, Qianli; Liu, Xujie; Elkhooly, Tarek A; Zhang, Ranran; Shen, Zhijian; Feng, Qingling

    2015-10-01

    Recently, surface micron/nano-topographical modifications have attracted a great deal of attention because it is capable of mimicking the hierarchical characteristics of bone. In the current work, a novel titania/calcium silicate hydrate (CSH) bi-layer coating with hierarchical surface topography was successfully prepared on titanium substrate through micro-arc oxidation (MAO) and subsequent hydrothermal treatment (HT). MAO treatment could lead to a micron-scale topographical surface with numerous crater-like protuberances. The subsequent HT process enables the in situ nucleation and growth of CSH nanoplates on MAO-fabricated titania surface. The nucleation of CSH nanoplates is considered to follow a dissolution-precipitation mechanism. Compared to MAO-fabricated coating with single-scale surface topography, MAO-HT-fabricated coating with hierarchical surface topography exhibits enhanced hydrophilicity, fibronectin adsorption and initial MG-63 cell attachment. The process of cell-material interactions is considered to be triggered by surface properties of the coated layer and indirectly mediated by protein adsorption on coating surface. These results suggest that MAO-HT treatment is an efficient way to prepare coatings with hierarchical surface topography on titanium surface, which is essential for altering protein adsorption and initial cell attachment. PMID:26196089

  6. Electrodeposition of porous hydroxyapatite/calcium silicate composite coating on titanium for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yong; Han, Shuguang [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); Pang, Xiaofeng, E-mail: pxf2012@yahoo.com.cn [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China); International Centre for Materials Physics, Chinese Academy of Science, Shenyang 110015 (China); Ding, Qionqion; Yan, Yajing [Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2013-04-15

    A novel method of electrolytic porous hydroxyapatite/calcium silicate (HA/CaSiO{sub 3}) composite coating was conducted on pure titanium in a mixed solution of nano-SiO{sub 2}, Ca(NO{sub 3}){sub 2} and NH{sub 4}H{sub 2}PO{sub 4}. SEM observation showed that the composite layer was porous, thereby providing abundant sites for the osteoblast adhesion. XRD results showed that the composite coating was mainly composed of HA and CaSiO{sub 3}. Bond strength testing exhibited that HA-CaSiO{sub 3}/Ti had higher bond strength than HA/Ti. The HA/CaSiO{sub 3} coating was more corrosion resistant than the HA coating based on the polarization tests. In vitro cell experiments demonstrated that both the HA and HA/CaSiO{sub 3} coatings showed better cell response than the bared titanium. In addition, the proliferation of MC3T3-E1 osteoblast cells grown on the HA/CaSiO{sub 3} coating were remarkably higher than those on the bared Ti and pure HA coating.

  7. Electrodeposition of porous hydroxyapatite/calcium silicate composite coating on titanium for biomedical applications

    Science.gov (United States)

    Huang, Yong; Han, Shuguang; Pang, Xiaofeng; Ding, Qionqion; Yan, Yajing

    2013-04-01

    A novel method of electrolytic porous hydroxyapatite/calcium silicate (HA/CaSiO3) composite coating was conducted on pure titanium in a mixed solution of nano-SiO2, Ca(NO3)2 and NH4H2PO4. SEM observation showed that the composite layer was porous, thereby providing abundant sites for the osteoblast adhesion. XRD results showed that the composite coating was mainly composed of HA and CaSiO3. Bond strength testing exhibited that HA-CaSiO3/Ti had higher bond strength than HA/Ti. The HA/CaSiO3 coating was more corrosion resistant than the HA coating based on the polarization tests. In vitro cell experiments demonstrated that both the HA and HA/CaSiO3 coatings showed better cell response than the bared titanium. In addition, the proliferation of MC3T3-E1 osteoblast cells grown on the HA/CaSiO3 coating were remarkably higher than those on the bared Ti and pure HA coating.

  8. The Performance of Calcium Silicate Board Partition Fireproof Drywall Assembly with Junction Box under Fire

    Directory of Open Access Journals (Sweden)

    Yinuo Wang

    2015-01-01

    Full Text Available This study uses a metal stud partition fireproof drywall measuring 83 mm in thickness as a test specimen to explore the impact of an embedded junction box on the firefighting performance of the wall through one time of standard fire test on a 300 cm × 300 cm area and five times of standard fire test on a 120 cm × 120 cm area. The results show that the quality of calcium silicate board plays a big role in the fireproof effectiveness. The embedded junction box located on the backside of the fire can reduce the effectiveness of the wall, especially the area above the socket. The thickness of rock wool may increase the performance, but in a limited rate. External junction box may not impact the fireproofing performance of the wall but it still possesses some safety risks. An embedded junction box measuring 101 × 55 mm could already damage the fire compartment, and in reality there may be more complicated situations that should be noted and improved.

  9. Combination of simvastatin, calcium silicate/gypsum, and gelatin and bone regeneration in rabbit calvarial defects

    Science.gov (United States)

    Zhang, Jing; Wang, Huiming; Shi, Jue; Wang, Ying; Lai, Kaichen; Yang, Xianyan; Chen, Xiaoyi; Yang, Guoli

    2016-03-01

    The present study was performed to determine whether simvastatin improves bone regeneration when combined with calcium silicate/gypsum and gelatin (CS-GEL). The surface morphology was determined using field-emission scanning electron microscopy (FSEM). Degradation in vitro was evaluated by monitoring the weight change of the composites soaked in phosphate buffered saline (PBS). Drug release was evaluated using high-performance liquid chromatography (HPLC). Cytotoxicity testing was performed to assess the biocompatibility of composites. Four 5 mm-diameter bone defects were created in rabbit calvaria. Three sites were filled with CS-GEL, 0.5 mg simvastatin-loaded CS-GEL (SIM-0.5) and 1.0 mg simvastatin-loaded CS-GEL (SIM-1.0), respectively, and the fourth was left empty as the control group. Micro-computed tomography (micro-CT) and histological analysis were carried out at 4 and 12 weeks postoperatively. The composites all exhibited three-dimensional structures and showed the residue with nearly 80% after 4 weeks of immersion. Drug release was explosive on the first day and then the release rate remained stable. The composites did not induce any cytotoxicity. The results in vivo demonstrated that the new bone formation and the expressions of BMP-2, OC and type I collagen were improved in the simvastatin-loaded CS-GEL group. It was concluded that the simvastatin-loaded CS-GEL may improve bone regeneration.

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

    International Nuclear Information System (INIS)

    The stability of the cement minerals ettringite, monosulfate, and calcium silicate hydrate (C-S-H) was investigated to better understand the uptake of contaminants in waste-cement mixes. Suspensions were spiked with radioisotopes of components (45Ca and 35SO4 for ettringite and monosulfate and 45Ca and 32Si for C-S-H) to observe their uptake behaviour within 0-70 days. A physical model was applied to determine 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 10-11.5 to 10-12.2 mol m-2 s-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

  11. Mechanical and microstructure of reinforced hydroxyapatite/calcium silicate nano-composites materials

    International Nuclear Information System (INIS)

    Highlights: ► Nano sized of HA and CS powders were prepared. ► Mechanical of HACS composites enhanced with content of CS. ► The apatite formation onto the composites is proved. -- Abstract: In this study, the nano sized hydroxyapatite (HA) and calcium silicate (CS) powders prepared by both chemical precipitation and sol–gel methods respectively. Biphasic nano-composites materials containing different ratios of HA and CS were fabricated and assessed using X-ray diffraction (XRD), Fourier transmission infrared reflectance (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The effect of variation of ratios between HA and CS on mechanical properties, microstructure and in vitro study was studied. The results proved that the mechanical properties were enhanced with increasing the CS ratio in the composite. In vitro study proved the formation and nucleation of apatite onto composites surfaces which contain low content of CS after one week of immersion. Finally, it is concluded that the HACS composites containing high HA content at the expense of CS content will be promising for bone substitute’s applications, especially in load bearing sites.

  12. Low-to-Medium-Frequency AC Impedance Spectroscopy Investigations of Nanocrystalline Calcium Silicate Hydrate Dried Powders

    International Nuclear Information System (INIS)

    Low-to-medium-frequency range impedance spectroscopy was used to investigate two series of dried calcium silicate hydrates with or without aluminum atoms, C-S-H and C-A-S-H. Over four decades in frequency, sample Nyquist plots were fitted by adopting an equivalent circuit using constant phase elements (CPE). Conductivity values of the order of 10-9-10-10 S/cm were obtained at 316 K. The presence of CPE characteristic of the depleted semicircle at high frequency was related to a fractal dimension ranging from 2.4 up to 2.7. Above 316 K, the impedance spectra behaved unpredictably due to the dehydration process, while below 316 K the behavior was followed by adopting the modulus loss factor. The associated peak maximum variation is of the Arrhenius-type. The entire behavior may be interpreted by ionic motion and charge accumulation in addition to dielectric polarization at the grain boundaries associated to low fractal surface. (authors)

  13. Interaction grand potential between calcium-silicate-hydrate nanoparticles at the molecular level.

    Science.gov (United States)

    Bonnaud, Patrick A; Labbez, Christophe; Miura, Ryuji; Suzuki, Ai; Miyamoto, Naoto; Hatakeyama, Nozomu; Miyamoto, Akira; Van Vliet, Krystyn J

    2016-02-21

    Calcium-silicate-hydrate (or C-S-H), an inosilicate, is the major binding phase in cement pastes and concretes and a porous hydrated material made up of a percolated and dense network of crystalline nanoparticles of a mean apparent spherical diameter of ∼5 nm that are each stacks of multiple C-S-H layers. Interaction forces between these nanoparticles are at the origin of C-S-H chemical, physical, and mechanical properties at the meso- and macroscales. These particle interactions and the resulting properties may be affected significantly by nanoparticle density and environmental conditions such as the temperature, relative humidity, or concentration of chemical species in the bulk solution. In this study, we combined grand canonical Monte Carlo simulations and an extension of the mean force integration method to derive the pair potentials. This approach enables realistic simulation of the physical environment surrounding the C-S-H particles. We thus constructed the pair potentials for C-S-H nanoparticles of defined chemical stoichiometry at 10% relative humidity (RH), varying the relative crystallographic orientations at a constant particle density of ρpart ∼ 2.21 mmol L(-1). We found that cohesion between nanoparticles is affected strongly by both the aspect ratio and the crystallographic misorientation of interacting particles. This method and the findings underscore the importance of accounting for relative dimensions and orientation among C-S-H nanoparticles in descriptions of physical and simulated multiparticle aggregates or mesoscale systems. PMID:26866999

  14. Electrodeposition of porous hydroxyapatite/calcium silicate composite coating on titanium for biomedical applications

    International Nuclear Information System (INIS)

    A novel method of electrolytic porous hydroxyapatite/calcium silicate (HA/CaSiO3) composite coating was conducted on pure titanium in a mixed solution of nano-SiO2, Ca(NO3)2 and NH4H2PO4. SEM observation showed that the composite layer was porous, thereby providing abundant sites for the osteoblast adhesion. XRD results showed that the composite coating was mainly composed of HA and CaSiO3. Bond strength testing exhibited that HA-CaSiO3/Ti had higher bond strength than HA/Ti. The HA/CaSiO3 coating was more corrosion resistant than the HA coating based on the polarization tests. In vitro cell experiments demonstrated that both the HA and HA/CaSiO3 coatings showed better cell response than the bared titanium. In addition, the proliferation of MC3T3-E1 osteoblast cells grown on the HA/CaSiO3 coating were remarkably higher than those on the bared Ti and pure HA coating.

  15. Combination of simvastatin, calcium silicate/gypsum, and gelatin and bone regeneration in rabbit calvarial defects.

    Science.gov (United States)

    Zhang, Jing; Wang, Huiming; Shi, Jue; Wang, Ying; Lai, Kaichen; Yang, Xianyan; Chen, Xiaoyi; Yang, Guoli

    2016-01-01

    The present study was performed to determine whether simvastatin improves bone regeneration when combined with calcium silicate/gypsum and gelatin (CS-GEL). The surface morphology was determined using field-emission scanning electron microscopy (FSEM). Degradation in vitro was evaluated by monitoring the weight change of the composites soaked in phosphate buffered saline (PBS). Drug release was evaluated using high-performance liquid chromatography (HPLC). Cytotoxicity testing was performed to assess the biocompatibility of composites. Four 5 mm-diameter bone defects were created in rabbit calvaria. Three sites were filled with CS-GEL, 0.5 mg simvastatin-loaded CS-GEL (SIM-0.5) and 1.0 mg simvastatin-loaded CS-GEL (SIM-1.0), respectively, and the fourth was left empty as the control group. Micro-computed tomography (micro-CT) and histological analysis were carried out at 4 and 12 weeks postoperatively. The composites all exhibited three-dimensional structures and showed the residue with nearly 80% after 4 weeks of immersion. Drug release was explosive on the first day and then the release rate remained stable. The composites did not induce any cytotoxicity. The results in vivo demonstrated that the new bone formation and the expressions of BMP-2, OC and type I collagen were improved in the simvastatin-loaded CS-GEL group. It was concluded that the simvastatin-loaded CS-GEL may improve bone regeneration. PMID:26996657

  16. In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics.

    Science.gov (United States)

    Pu, Yinfu; Huang, Yanlin; Qi, Shuyun; Chen, Cuili; Seo, Hyo Jin

    2015-10-01

    A novel calcium silicate borate Ca11Si4B2O22 ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca11Si4B2O22 ceramics were also measured, which indicate that the biomaterials based on Ca11Si4B2O22 ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si-OH) and B-OH groups can be easily induced on the surface of Ca11Si4B2O22 ceramics soaked in SBF solutions. PMID:26117746

  17. Preparation and characterization of high-strength calcium silicate boards from coal-fired industrial solid wastes

    Institute of Scientific and Technical Information of China (English)

    Zhao Cao; Yong-dan Cao; Jin-shan Zhang; Chun-bao Sun; Xian-long Li

    2015-01-01

    To realize the comprehensive utilization of coal-fired industrial solid wastes, a novel high-strength board was prepared from cal-cium silicate slag, fly ash, and flue gas desulfurization (FGD) gypsum. The changes in mineral phases, chemical structure, and morphology during hydration were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron mi-croscopy (SEM). A traditional board made from quartz and lime was prepared as a reference. The novel board not only consumes a lot of solid wastes, but also meets the strength requirement of the class-five calcium silicate board according to the Chinese Standard JC/T 564.2—2008. Microanalysis showed that hydrated calcium silicate gel (C−S−H(I)), ettringite, tobermorite, and xonotlite were successivelygenerated in the novel board by synergistic hydration of the mixed solid wastes. The board strength was improved by the formation of tobermorite and xonotlite but decreased by unhydrated quartz. It was demonstrated that quartz was not completely hydrated in the traditional board. As a re-sult, the flexural strength of the traditional board was much lower than that of the novel board.

  18. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO3 formulation were differ from the previous study due CaO/SiO2 amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO2 and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO2 content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure

  19. Preparation and characterization of high-strength calcium silicate boards from coal-fired industrial solid wastes

    Science.gov (United States)

    Cao, Zhao; Cao, Yong-dan; Zhang, Jin-shan; Sun, Chun-bao; Li, Xian-long

    2015-08-01

    To realize the comprehensive utilization of coal-fired industrial solid wastes, a novel high-strength board was prepared from calcium silicate slag, fly ash, and flue gas desulfurization (FGD) gypsum. The changes in mineral phases, chemical structure, and morphology during hydration were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). A traditional board made from quartz and lime was prepared as a reference. The novel board not only consumes a lot of solid wastes, but also meets the strength requirement of the class-five calcium silicate board according to the Chinese Standard JC/T 564.2—2008. Microanalysis showed that hydrated calcium silicate gel (C-S-H(I)), ettringite, tobermorite, and xonotlite were successively generated in the novel board by synergistic hydration of the mixed solid wastes. The board strength was improved by the formation of tobermorite and xonotlite but decreased by unhydrated quartz. It was demonstrated that quartz was not completely hydrated in the traditional board. As a result, the flexural strength of the traditional board was much lower than that of the novel board.

  20. Effects of Zn Content on Crystal Structure, Cytocompatibility, Antibacterial Activity, and Chemical Stability in Zn-Modified Calcium Silicate Coatings

    Science.gov (United States)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2013-08-01

    In our previous study, Zn-modified calcium silicate coatings possess not only excellent chemical stability but also well antibacterial activity. Still, effects of zinc content on these properties and cytocompatibility remain unclear. In this paper, two kinds of Zn-modified calcium silicate coatings (ZC0.3, ZC0.5) were fabricated on Ti-6Al-4V substrates via plasma spraying technology. X-ray diffraction results and transmission electron microscopy observations showed that the ZC0.5 coating was composed of pure hardystonite (Ca2ZnSi2O7) phase, while, besides Ca2ZnSi2O7 phase, the amorphous CaSiO3 phase was also detected in the ZC0.3 coating. Chemical stability in Tris-HCl buffer solution and antibacterial activity of the Zn-modified calcium silicate coatings increased with an increase in zinc content. In vitro cytocompatibility evaluation demonstrated that the proliferation and alkaline phosphatase activity and collagen type I (COLI) secretion of osteoblast-like MC3T3-E1 cells on Zn-modified coatings were significantly enhanced compared to the Zn-free coating and Ti-6Al-4V control, and no cytotoxicity appeared on Zn-modified coatings. The better antibacterial activity and the enhanced capability to promote MC3T3-E1 cells differentiation of Zn-modified coatings should be attributed to the slow and constant Zn2+ releasing from the coatings.

  1. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Farah ' Atiqah bt Abdul; Shamsudin, Roslinda, E-mail: linda@ukm.edu.my [School of Applied Physics, Faculty of Science and Technology Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia)

    2015-09-25

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO{sub 3} formulation were differ from the previous study due CaO/SiO{sub 2} amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO{sub 2} and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO{sub 2} content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure.

  2. Preliminary study of raw material for calcium silicate/PVA coating on Ti-6Al-4V alloy

    Science.gov (United States)

    Azam, Farah Atiqah bt Abdul; Shamsudin, Roslinda

    2015-09-01

    Calcium silicate bioceramic was prepared from the rice husk and limestone resources using the sol gel method. The preparations of CaSiO3 formulation were differ from the previous study due CaO/SiO2 amount with 45:55 ratio. X-Ray Fluorescence analysis was carried out to clarify the amount of SiO2 and CaO content in the limestone and rice husk ash. The high amount of CaO was found in the limestone with the percentages of 97.22%, whereby 89% of SiO2 content of the rice husk ash. Several milling time were studied to obtain the optimized milling ti me and speed in progress to obtain nano size particle. The particle size analysis result confirms that increase in milling time does not certainly reduce the size of particle. The addition of 0.05% polyvinyl alcohol as a binder did not change the phases or composition of calcium silicates after examined by X-Ray diffraction analysis which make it suitable to be used as a binder for calcium silicate coating without changing the chemical structure.

  3. Fluoride-containing nanoporous calcium-silicate MTA cements for endodontics and oral surgery: Early fluorapatite formation in a phosphate-containing solution

    OpenAIRE

    Gandolfi, M.G.; Taddei, P.; Siboni, F.; Modena, E.; Ginebra Molins, Maria Pau; Prati, Claudio

    2011-01-01

    Gandolfi MG, Taddei P, Siboni F, Modena E, Ginebra MP, Prati C. Fluoride-containing nanoporous calcium-silicate MTA cements for endodontics and oral surgery: early fluorapatite formation in a phosphate-containing solution. International Endodontic Journal, 44, 938–949, 2011. Aim To test the chemical–physical properties and apatite-forming ability of experimental fluoride-doped calcium silicate cements designed to create novel bioactive materials for use in endodontics ...

  4. Spontaneous and CRH-Induced Excitability and Calcium Signaling in Mice Corticotrophs Involves Sodium, Calcium, and Cation-Conducting Channels.

    Science.gov (United States)

    Zemkova, Hana; Tomić, Melanija; Kucka, Marek; Aguilera, Greti; Stojilkovic, Stanko S

    2016-04-01

    Transgenic mice expressing the tdimer2(12) form of Discosoma red fluorescent protein under control of the proopiomelanocortin gene's regulatory elements are a useful model for studying corticotrophs. Using these mice, we studied the ion channels and mechanisms controlling corticotroph excitability. Corticotrophs were either quiescent or electrically active, with a 22-mV difference in the resting membrane potential (RMP) between the 2 groups. In quiescent cells, CRH depolarized the membrane, leading to initial single spiking and sustained bursting; in active cells, CRH further facilitated or inhibited electrical activity and calcium spiking, depending on the initial activity pattern and CRH concentration. The stimulatory but not inhibitory action of CRH on electrical activity was mimicked by cAMP independently of the presence or absence of arachidonic acid. Removal of bath sodium silenced spiking and hyperpolarized the majority of cells; in contrast, the removal of bath calcium did not affect RMP but reduced CRH-induced depolarization, which abolished bursting electrical activity and decreased the spiking frequency but not the amplitude of single spikes. Corticotrophs with inhibited voltage-gated sodium channels fired calcium-dependent action potentials, whereas cells with inhibited L-type calcium channels fired sodium-dependent spikes; blockade of both channels abolished spiking without affecting the RMP. These results indicate that the background voltage-insensitive sodium conductance influences RMP, the CRH-depolarization current is driven by a cationic conductance, and the interplay between voltage-gated sodium and calcium channels plays a critical role in determining the status and pattern of electrical activity and calcium signaling. PMID:26901094

  5. Characterization and leach investigations of sodium silicate matrices used for immobilization of radioactive waste

    International Nuclear Information System (INIS)

    In this study, simulated liquid waste and radioactive tracers of Cs-137 and Co-60 were used to represent the high-level liquid waste (HLLW). immobilization of the liquid waste was performed by its interaction with commercial sodium silicate hydrosol to the gel point, at room temperature. The candidate waste forms forms were fabricated from the obtained hydrogel through several steps including: drying the hydrogel to a solid gel form, crushing the solid to be in a powder from, pressing the powder to the green disk form using a cold pressing technique and finally the heat treatment of the green disks to the sintered form. Characterization for the obtained waste forms was carried out using: thermal analysis (TGA and DTA), X-ray powder diffraction (XRD) techniques and porosity investigation. The leach tests for the prepared forms were conducted according to the international atomic energy agency (IAEA) standard test (static and accelerated). The static test was carried out for simulated and radioactive waste in distilled, bidistilled and ground water for 28 days. The accelerated (Soxhlet) test was conducted for simulated waste in deionized water for 72 hours. 4 figs., 7 tabs

  6. Formation of magnesium silicate hydrate (M-S-H) cement pastes using sodium hexametaphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tingting [Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024 (China); Department of Materials, Centre for Advanced Structural Ceramics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Vandeperre, Luc J. [Department of Materials, Centre for Advanced Structural Ceramics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Cheeseman, Christopher R., E-mail: c.cheeseman@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

    2014-11-15

    Magnesium silicate hydrate (M-S-H) gel is formed by the reaction of brucite with amorphous silica during sulphate attack in concrete and M-S-H is therefore regarded as having limited cementing properties. The aim of this work was to form M-S-H pastes, characterise the hydration reactions and assess the resulting properties. It is shown that M-S-H pastes can be prepared by reacting magnesium oxide (MgO) and silica fume (SF) at low water to solid ratio using sodium hexametaphosphate (NaHMP) as a dispersant. Characterisation of the hydration reactions by x-ray diffraction and thermogravimetric analysis shows that brucite and M-S-H gel are formed and that for samples containing 60 wt.% SF and 40 wt.% MgO all of the brucites react with SF to form M-S-H gel. These M-S-H cement pastes were found to have compressive strengths in excess of 70 MPa.

  7. Formation of magnesium silicate hydrate (M-S-H) cement pastes using sodium hexametaphosphate

    International Nuclear Information System (INIS)

    Magnesium silicate hydrate (M-S-H) gel is formed by the reaction of brucite with amorphous silica during sulphate attack in concrete and M-S-H is therefore regarded as having limited cementing properties. The aim of this work was to form M-S-H pastes, characterise the hydration reactions and assess the resulting properties. It is shown that M-S-H pastes can be prepared by reacting magnesium oxide (MgO) and silica fume (SF) at low water to solid ratio using sodium hexametaphosphate (NaHMP) as a dispersant. Characterisation of the hydration reactions by x-ray diffraction and thermogravimetric analysis shows that brucite and M-S-H gel are formed and that for samples containing 60 wt.% SF and 40 wt.% MgO all of the brucites react with SF to form M-S-H gel. These M-S-H cement pastes were found to have compressive strengths in excess of 70 MPa

  8. Synthesis and characterization of hollow silica particles from tetraethyl orthosilicate and sodium silicate.

    Science.gov (United States)

    Kim, Jiwoong; Lee, Jinwoo; Choi, Jeong-Woo; Jang, Hee Dong

    2013-03-01

    We herein introduce an effective method to synthesize hollow silica particles (HSPs) from tetraethyl orthosilicate (TEOS) and sodium silicate (Na2SiO3) as silica sources using a sacrificial template method with a simple modification. The advantage of the method is that it can be applied to synthesize HSPs from not only TEOS but also Na2SiO3 silica sources without changing the method adopted to obtain the sacrificial polymeric templates. Polystyrene particles are adopted as sacrificial templates to synthesize the HSPs, and a conventional dispersion polymerization method is used to synthesis polystyrene particles in an oil medium. Size control of HSPs is enabled by modulation of the polymerization initiator content (2,2'-Azoisobutyronitrile). The particle size, shell thickness, and morphology are analyzed. Light reflection spectra are measured to obtain the light reflection properties of the HSPs. The results indicate that the hollow architecture is the most important factor in determining the light reflection properties of the particles. Such particles are potential candidates for use in light reflectors and heat insulators, as they may reduce energy consumption in heating and cooling applications. PMID:23755680

  9. Effect of concentration of sodium silicate solution in the synthesis of silica-coated magnetite nanoparticles by ultrasonication

    Science.gov (United States)

    Fajaroh, Fauziatul; Sumari, Nazriati

    2016-02-01

    An ex-situ silica coating of magnetite nanoparticles synthesized electrochemically had been successfully carried out by ultrasonication. An aqueous solution of sodium silicate had been used as silica source.The Si-O-Si, Si-O and Fe-O-Si bonds on the surface of the silica-coated magnetite had been successfully identified using FTIR. Reduction in particle size due to the influence of ultrasound was studied using SEM. Enhancement in the specific surface area of the particles due to the silica coating and reduction in particle size was learned through BET analysis. The Characters of the resulting silica-coated magnetite were influenced by the concentration of sodium silicate solution. The greater the concentration of sodium silicate solution, the smaller the particle crystallinity and the larger the particles surface area was produced. The resulting silica-coated magnetite has a surface area of 38.171 to 67.993 m2/g, otherwise the non-coated particles only has a surface area of 27.894 m2/g. This silica-coated magnetite nanoparticles has more potent as an adsorbent than that of the bare magnetite. Besides that, the presence of silanol groups on its surface makes an opportunity for further functionalization needed for some applications.

  10. Intake of protein, calcium and sodium in public child day care centers

    Directory of Open Access Journals (Sweden)

    Giovana Longo-Silva

    2014-06-01

    Full Text Available OBJECTIVE:To assess calcium, protein and sodium intake, of children that attend public day-care centers and to compare it with the recommended one.METHODS:Cross-sectional descriptive study in seven public day care centers of São Paulo city, Southeast Brazil, which enrolled 366 children between 12 and 36 months of age. The data collection occurred between September and December 2010. Each day care center was evaluated for three non-consecutive days, totaling 42 days and 210 meals. Dietary intake was assessed by a direct food weighing method. For the nutritional calculation, DietWin(r Profissional 2.0 was used, and the adequacy was calculated according to the recommendations of the National School Feeding Program for energy, protein, calcium and sodium. The calcium/protein relation was also calculated, as well as calcium density (mg/1,000kcal.RESULTS: The energy (406.4kcal, protein (18.2g and calcium (207.6mg consumption did not reach the recommended values ​​in all the evaluated day care centers. Sodium intake exceeded up to three times the recommendation. The calcium/protein ratio of 11.7mg/g was less than the adequate one (20mg/g.CONCLUSIONS: There was inadequacy of calcium, protein and sodium dietary intake, in children attending public day-care centers.

  11. Scientific Opinion on the safety assessment of the active substances, sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulphate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, for use as active system in food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2014-02-01

    Full Text Available This scientific opinion of EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety assessment of the active substances sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulfate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water, used in mixture which is packed into sachets for absorbing oxygen/carbon dioxide emitting from/into the headspace surrounding packed food. All substances of this formulation have been evaluated and approved for use as additives in plastic food contact materials or as food additives. No migration of calcium, iron and sodium ions was detected. No volatile organic compounds other than carbon dioxide were detected at the limit of detection of 0.5 μg/l. The CEF Panel concluded that the use of the substances sodium erythorbate, sodium carbonate, sodium bicarbonate, iron sulfate, activated carbon, cellulose, calcium hydroxide, calcium chloride and water does not raise a safety concern when used in oxygen absorber/carbon dioxide emitter systems, in sachets that prevent the physical release of their contents into the food. The sachets are to be placed in the headspace of the packaging and as such may come into occasional contact with the food, e.g. during handling. The sachet should not come into direct contact with liquid foods or foods that have and external aqueous liquid phase on the surface (liquid or exudates.

  12. Sodium/Calcium Exchangers Selectively Regulate Calcium Signaling in Mouse Taste Receptor Cells

    OpenAIRE

    Szebenyi, Steven A.; Laskowski, Agnieszka I.; Medler, Kathryn F.

    2010-01-01

    Taste cells use multiple signaling mechanisms to generate appropriate cellular responses to discrete 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). While the signaling mechanisms that initiate calcium signals have been described in taste cells, the calcium clearance mechanisms (CCMs) that contrib...

  13. Effect of calcium silicate slag application on radium-226 concentrations in plant tissues

    International Nuclear Information System (INIS)

    A greenhouse pot experiment was conducted to determine if plants absorb Ra from slag applied to soil. Slag at rates equivalent to 0 and 22 mt/ha was mixed with Mountview silt loam (Typic Paleudults) limed to pH 5.8 and 7.2. Three clippings each of fescue (Festuca arundiancea Schreb.), and Swiss chard (Beta vulgaris L.), and one harvest of wheat (Triticum aestivum L.) for grain and straw were grown on separate series of treated soil, and plant samples were analyzed for radioactivity due to 226Ra uptake. Samples of sugarcane (Saccharum officinarum L.) forage and extracted juice from field experiments in Florida testing this slage as a Si source also were analyzed for radioactivity. Dry forage yields of fescue and wheat were not affected by slag applications, but those of Swiss chard were somewhat higher on slag-treated soil at pH 5.8. Wheat grain and straw yields were higher on soil at pH 7.2 than at pH 5.8 regardless of slag treatment. Uptake of 226Ra by fescue forage and wheat grain and straw was not affected by slag application. Concentrations of 226Ra were similar in forage and extracted juice from untreated sugarcane or that treated with slag at rates up to 5.6 mt/ha. These results suggest that plant uptake of radionuclides is negligible from calcium silicate slag applied at the recommended rates for liming acid soils or as a source of Si for sugarcane

  14. Luminescence properties of dysprosium doped calcium magnesium silicate phosphor by solid state reaction method

    International Nuclear Information System (INIS)

    Dysprosium doped calcium magnesium silicate (CaMgSi2O6:Dy3+) white light emitting phosphor was synthesized by solid state reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi2O6:Dy3+ phosphor was confirmed by EDX. The prepared CaMgSi2O6:Dy3+ phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 transitions of Dy3+ ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi2O6:Dy3+ phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi2O6:Dy3+ phosphor. - Highlights: • The crystal structure of CaMgSi2O6:Dy3+ phosphor is consistent with standard monoclinic structure. • CIE coordinates of CaMgSi2O6:Dy3+ phosphor is suitable as white light emitting phosphor. • The local piezoelectricity-induced electron bombardment model is responsible to produce ML in CaMgSi2O6:Dy3+ phosphor

  15. Luminescence properties of dysprosium doped di-calcium di-aluminium silicate phosphors

    Science.gov (United States)

    Tiwari, Geetanjali; Brahme, Nameeta; Sharma, Ravi; Bisen, D. P.; Sao, Sanjay K.; Tigga, Shalinta

    2016-08-01

    A Dysprosium doped di-calcium di-aluminium silicate phosphor emitting long-lasting white light was prepared and investigated. Phosphors were synthesized by combustion-assisted method. The effect of doping concentration on the crystal structure and luminescence properties of Ca2Al2SiO7:Dy3+ phosphors were investigated. The phase structure, surface morphology, particle size, elemental analysis was analyzed by using X-ray diffraction (XRD), transmission electron microscope (TEM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) techniques. X-ray diffraction (XRD) profiles showed that all peaks could be attributed to the tetragonal Ca2Al2SiO7 phase when the sample was annealed at 1100 °C. The increase in TL intensity indicates that the concentration of traps increases with UV irradiation. Under the UV-excitation, the Thermoluminescence (TL) emission spectra of Ca2Al2SiO7:Dy3+ phosphor shows the characteristic emission of Dy3+ peaking at 484 nm (blue), 583 nm (yellow) and 680 nm (red), originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2. Photoluminescence (PL) decay has also reported and it indicates that Ca2Al2SiO7:Dy3+ phosphor contains fast decay and slow decay process. The peak of Mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. The possible mechanism of Thermoluminescence (TL), Photoluminescence (PL) and Mechanoluminescence (ML) of this white light emitting long lasting phosphor is also investigated.

  16. Improvement of in vitro physicochemical properties and osteogenic activity of calcium sulfate cement for bone repair by dicalcium silicate

    International Nuclear Information System (INIS)

    Highlights: • Dicalcium silicate can improve osteogenic activity of calcium sulfate cement. • The higher the calcium sulfate content, the shorter the setting time in the composite cement. • The results were useful for designing calcium-based cement with optimal properties. -- Abstract: An ideal bone graft substitute should have the same speed of degradation as formation of new bone tissue. To improve the properties of calcium sulfate hemihydrate (CSH) featured for its rapid resorption, a low degradation material of dicalcium silicate (DCS) was added to the CSH cement. This study examined the effect of DCS (20, 40, 60 and 80 wt%) on the in vitro physicochemical properties and osteogenic activities of the calcium-based composite cements. The diametral tensile strength, porosity and weight loss of the composite cements were evaluated before and after soaking in a simulated body fluid (SBF). The osteogenic activities, such as proliferation, differentiation and mineralization, of human mesenchymal stem cells (hMSCs) seeded on cement surfaces were also examined. As a result, the greater the DCS amount, the higher the setting time was in the cement. Before soaking in SBF, the diametral tensile strength of the composite cements was decreased due to the introduction of DCS. On 180-day soaking, the composite cements containing 20, 40, 60 and 80 wt% DCS lost 80%, 69%, 61% and 44% in strength, respectively. Regarding in vitro bioactivity, the DCS-rich cements were covered with clusters of apatite spherulites after soaking for 7 days, while there was no formation of apatite spherulites on the CSH-rich cement surfaces. The presence of DCS could reduce the degradation of the CSH cements, as evidenced in the results of weight loss and porosity. More importantly, DCS may promote effectively the cell proliferation, proliferation and mineralization. The combination of osteogenesis of DCS and degradation of CSH made the calcium-based composite cements an attractive choice for

  17. Effect of natural fiber types and sodium silicate coated on natural fiber mat/PLA composites: Tensile properties and rate of fire propagation

    Science.gov (United States)

    Thongpin, C.; Srimuk, J.; hipkam, N.; Wachirapong, P.

    2015-07-01

    In this study, 3 types of natural fibres, i.e. jute, sisal and abaca, were plain weaved to fibre mat. Before weaving, the fibres were treated with 5% NaOH to remove hemi cellulose and lignin. The weaving was performed by hand using square wooden block fit with nails for weaving using one and two types of natural fibres as weft and warp fibre to produce natural fibre mat. The fibre mat was also impregnated in sodium silicate solution extracted from rich husk ash. The pH of the solution was adjusted to pH 7 using H2SO4 before impregnation. After predetermined time, sodium silicate was gelled and deposited on the mat. The fabric mat and sodium silicate coated mat were then impregnated with PLA solution to produce prepreg. Dried pepreg was laminated with PLA sheet using compressing moulding machine to obtain natural fibre mat/PLA composite. The composite containing abaca aligned in longitudinal direction with respect to tension force enhanced Young's modulus more than 300%. Fibre mat composites with abaca aligned in longitudinal direction also showed tensile strength enhancement nearly 400% higher than neat PLA. After coating with sodium silicate, the tensile modulus of the composites was found slightly increased. The silicate coating was disadvantage on tensile strength of the composite due to the effect of sodium hydroxide solution that was used as solvent for silicate extraction from rice husk ash. However, sodium silicate could retard rate of fire propagation about 50%compare to neat PLA and about 10% reduction compared to fibre mat composites without sodium silicate coated fibre mat.

  18. One-step synthesis of silica-coated magnetite nanoparticles by electrooxidation of iron in sodium silicate solution

    International Nuclear Information System (INIS)

    Silica-coated magnetite nanoparticles have been synthesized successfully using a one-step electrochemical method. In this method, pure iron in a dilute aqueous sodium silicate solution that served as a silica precursor was electrooxidized. We show that the presence of silicate can significantly enhance the purity of the magnetite formed. Impurities in the form of FeOOH (found in the magnetite prepared in water) are not found. The magnetite nanoparticles produced by this method are nearly spherical with a mean size ranging from 6 to 10 nm, which is lower than the size of particles prepared in water, and this size range depends on the applied voltage and the sodium silicate concentration. The magnetite nanoparticles exhibit superparamagnetic properties with saturation magnetization ranging from 15 to 22 emu g−1, which is lower than the saturation magnetization of the Fe3O4 bulk materials (Ms = 92 emu g−1). This facile method appears to be promising as a synthetic route for producing silica-coated magnetite nanoparticles.

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

    Science.gov (United States)

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

    2010-06-01

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

  20. Direct determination of calcium, sodium and potassium in fermented milk products

    Directory of Open Access Journals (Sweden)

    Kravić Snežana Ž.

    2012-01-01

    Full Text Available The aim of this study was the investigation of the possibilities of direct determination of calcium, sodium and potassium in the commercial and kombucha-based fermented milk products by flame photometry. Two procedures were used for sample preparation: simple dilution with water (direct method and extraction with mineral acid. Calcium, sodium and potassium levels determined after mentioned sample preparation methods were compared. The results showed that the differences between the values obtained for the different sample treatment were within the experimental error at the 95% confidence level. Compared to the method based on extraction with mineral acid, the direct method is efficient, faster, simpler, cheaper, and operates according to the principles of Green Chemistry. Consequently, the proposed method for the direct determination of calcium, sodium and potassium could be applied for the rapid routine analysis of the mineral content in the fermented dairy products. [Projekat Ministarstva nauke Republike Srbije, br. III 46009

  1. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    Science.gov (United States)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  2. Changes on the nanostructure of cementitius calcium silicate hydrates (C-S-H) induced by aqueous carbonation

    OpenAIRE

    Morales-Florez, Víctor; Findling, N.; F. Brunet

    2015-01-01

    The nanostructure of the main binding phase of the hydrated cements, the calcium silicate hydrates (C-S-H), and their structural changes due to aqueous carbonation have been characterized using TEM, nitrogen physisorption, and SAXS. Synthetic C-S-H has been used for this purpose. Two different morphologies were identified, similar to the high density and low density C-S-H types. When submitting the sample to a CO 2 flux, the low density phase was completely carbonated. The carbonation by-prod...

  3. Clinical and Radiographic Assessment of the Efficacy of Calcium Silicate Indirect Pulp Capping

    Science.gov (United States)

    Hashem, D.; Mannocci, F.; Patel, S.; Manoharan, A.; Brown, J.E.; Watson, T.F.

    2015-01-01

    The aims of this study were to assess the effectiveness of calcium silicate cement (Biodentine) versus glass ionomer cement (GIC; control group) as indirect pulp capping materials in patients with reversible pulpitis and to compare the effectiveness of cone beam computed tomography (CBCT) versus periapical (PA) radiographs in detecting PA changes at baseline (T0) and at 12 mo (T12) postoperatively. Seventy-two restorations (36 Biodentine, 36 Fuji IX) were placed randomly in 53 patients. CBCT/PA radiographs were taken at T0 and T12. Two calibrated examiners assessed the presence/absence and increase/decrease in the size of existing PA radiolucencies under standardized conditions. The Kappa coefficient evaluated statistically the effectiveness of CBCT versus PA radiographs in detecting PA changes. Chi-square/Mann-Whitney tests were used to evaluate the association between PA changes in CBCT with various clinical measures. Significance was predetermined at α = 0.05. Clinical success rates for Biodentine and Fuji IX GIC were 83.3%. CBCT was significantly more effective in detecting PA radiolucencies compared with radiographs (P = 0.0069). Of the teeth, 65.4% and 90.4% were deemed healthy using CBCT and PA radiographs, respectively, at T12. Healing/healed rates were 17.3%/0%, while new/progressed radiolucency were 30.8%/9.6% with CBCT/PA radiographs, respectively. Seventy-one percent of healed lesions had received Biodentine; 88% of new/progressed lesions received Fuji IX GIC. Teeth presenting with an initial CBCT PA lesion had a failure rate of 63%, whereas teeth with no initial lesion had a failure rate of 16%. Although no statistically significant difference was detected in the clinical efficacy of Biodentine/Fuji IX when used as indirect pulp capping materials in patients with reversible pulpitis, CBCT showed a significant difference in that most healed CBCT lesions had received Biodentine while most that did not heal received Fuji IX. Longer-term follow-up is

  4. Luminescence properties of dysprosium doped calcium magnesium silicate phosphor by solid state reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Ishwar Prasad, E-mail: ishwarprasad1986@gmail.com [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Chandrakar, Priya; Baghel, R.N.; Bisen, D.P.; Brahme, Nameeta [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Tamrakar, Raunak Kumar [Department of Applied Physics, Bhilai Institute of Technology, Durg, C.G. 491001 (India)

    2015-11-15

    Dysprosium doped calcium magnesium silicate (CaMgSi{sub 2}O{sub 6}:Dy{sup 3+}) white light emitting phosphor was synthesized by solid state reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was confirmed by EDX. The prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 11/2} transitions of Dy{sup 3+} ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor. - Highlights: • The crystal structure of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is consistent with standard monoclinic structure. • CIE coordinates of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is suitable as white light emitting phosphor. • The local piezoelectricity-induced electron bombardment model is responsible to produce ML in CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor.

  5. Comparison of sodium and calcium heparin in prevention of venous thromboembolism.

    Science.gov (United States)

    Cade, J F; Andrews, J T; Stubbs, A E

    1982-10-01

    The relative efficacy of sodium and calcium heparin in preventing venous thromboembolism and their relative side-effects were studied in 234 high-risk patients in a randomised, double-blind, placebo-controlled trial. The two heparin preparations were from the same batch and in the same concentration, and were given in a dose of 5000 U 12 hourly. Positive leg scans were found in 19% after placebo, 12% after sodium heparin and 8% after calcium heparin. Bruising at the injection site was more common after calcium heparin (66%) than after sodium heparin (53%) or placebo (38%). Pain at the injection site was also more common after calcium heparin (26%) than after sodium heparin (8%) or placebo (6%). Changes in the activated partial thromboplastin time were small and did not correlate with leg scan results or bruising. While there was a tendency for calcium heparin to be possibly more effective, it was followed by significantly more local haematoma and pain. PMID:6758747

  6. Sodium calcium orthovanadate, NaCa4(VO4)3.

    Science.gov (United States)

    Ben Yahia, Hamdi; Gaudin, Etienne; Darriet, Jacques

    2005-07-01

    Single crystals of sodium tetracalcium trivanadium dodecaoxide were prepared by melting a powder sample of NaCa4(VO4)3 at 1673 K, followed by slow cooling to room temperature. The compound crystallizes in the Pnma space group and is isostructural with the mineral silicocarnotite, Ca5(PO4)2SiO4. The structure is composed of isolated VO4 tetrahedra linked by sodium and calcium cations disordered over eight- and seven-coordinated sites. PMID:15997052

  7. Microanalyses of the hydroxyl—poly—calcium sodium phosphate coatings produced by ion beam assisted deposition

    Institute of Scientific and Technical Information of China (English)

    LIUZhong-Yang; WANGChang-Xing; 等

    2002-01-01

    Thin calcium phosphate catings on titanium alloy substrates were prepared by Ar+ ion beam assisted deposition(IBAD) from hydroxyl-poly-calcium sodium phosphate(HPPA) target.The coatings were analyzed by XRD,FTIR,XPS,These analyses revealed that the as-deposited films were amorphous or no apparent crystallinity.No distinct absorption band of the hydroxyl group was observed in FTIR spectra of the coatings but new absorption bands were presented for CO3-2,The calcium to phosphorous ratio of these catings in different IBAD conditions varied from 0.46 to 3.36.

  8. Interaction of calcium silicate hydrates (C-S-H), the main components of cement, with alkaline chlorides, analogy with clays; Interaction des silicates de calcium hydrates, principaux constituants du ciment, avec les chlorures d'alcalins. Analogie avec les argiles

    Energy Technology Data Exchange (ETDEWEB)

    Viallis-Terrisse, H

    2000-10-06

    This work, belonging to a more general study on the structure and reactivity of cement, deals with the experimental and theoretical analysis of the interaction of alkaline chlorides with calcium silicate hydrates (C-S-H), the main components of cement paste. The interaction of alkaline cations with C-S-H is interfacial, involving both electrostatic and surface complexation mechanisms. The C-S-H surface is constituted of silanol sites, partially dissociated due to the high pH of the interstitial solution. The calcium ions, present in large amounts in the equilibrium solution of C-S-H, constitute potential determining ions for the C-S-H surface. The alkaline ions seem to compete with calcium for the same surface sites. The adsorption isotherms show that caesium presents a better affinity than sodium and lithium for the C-S-H surface. Moreover, solid-state NMR suggests that caesium forms with the surface sites inner-sphere complexes, whereas sodium seems to keep its hydration sphere. These results are in agreement with zeta potential measurements, which let suppose a specific adsorption of caesium ions, and an indifferent behaviour of both other alkaline ions. A model for the C-S-H surface was proposed, from the electric double layer model, and mass action laws expressing the complexation of the different ionic species with the silanol sites. The whole study relies on a structural analogy with smectites, some clays presenting well-known cationic adsorption properties. The structural similarity between both minerals is enhanced by some similarities of reactivity, though significant behaviour differences could also be noted. (author)

  9. Structural study and crystallography of the major compound of anhydrous cement: tri-calcium silicate; Etude structurale et cristallographie du compose majoritaire du ciment anhydre: le silicate tricalcique

    Energy Technology Data Exchange (ETDEWEB)

    Noirfontaine, M.N. de

    2000-01-01

    Anhydrous (Portland) cement is mainly composed of a synthetic material, the clinker, whose major compound is tri-calcium silicate (Ca{sub 3}SiO{sub 5}), often referred as C{sub 3}S with the compact oxides notations, C = CaO et S = SiO{sub 2}. The polymorphism of C{sub 3}S, still not well known, is the main subject of the thesis. Various crystal structures (rhombohedral R, monoclinic M1, M2, M3 and triclinic T1, T2, T3) can be found, depending on temperature and impurities. The only known structures are T1, M1 and M3, involving large unit cells with an orientational disorder of silicate tetrahedra. The single crystal studies exhibit no clear relation between the various polymorphs. Starting from known results from literature single crystal experiments, we establish the metric and structural relations between the different structures. Averaged structures for the T1, M1 and M3 polymorphs are proposed, together with all the matrices of transformation between the unit cells. We also introduce new 1-D, 2-D, and 3-D structural units, which make easier the understanding of the structures of C{sub 3}S, with the result of a better description of the orientational disorder. The effects of impurities on the structure are discussed. In industrial clinkers, impurities stabilize mainly M1 and M3 monoclinic forms. We propose a space group (Pc) and two structural models (a superstructure and an approximate averaged structure) for the M1 form. All the models are validated on synthetic compounds (M3, M2, M1 et T1) and industrial clinkers analysed by X-Ray powder diffraction with Rietveld analysis. (author)

  10. Preparation and rebinding properties of protein-imprinted polysiloxane using mesoporous calcium silicate grafted non-woven polypropylene as matrix.

    Science.gov (United States)

    Kan, Bohong; Feng, Lingzhi; Zhao, Kongyin; Wei, Junfu; Zhu, Dunwan; Zhang, Linhua; Ren, Qian

    2016-03-01

    Calcium silicate particle containing mesoporous SiO2 (CaSiO3@SiO2) was grafted on the surface of non-woven polypropylene. The PP non-woven grafted calcium silicate containing mesoporous SiO2 (PP-g-CaSiO3@SiO2) was used as the matrix to prepare bovine serum albumin (BSA) molecularly imprinted polysiloxane (MIP) by using silanes as the functional monomers and BSA as the template. PP non-woven grafted BSA-imprinted polysiloxane (PP-g-CaSiO3@SiO2 MIP) was characterized by scanning electron microscope (SEM), Fourier transform infrared spectometry (FTIR) and drilling string compensator (DSC). Influence factors on the rebinding capacity of the MIP were investigated, such as grafting degree, the pH in treating CaSiO3 and the type and proportion of silanes. The rebinding properties of BSA on PP-g-CaSiO3@SiO2 and MIP were investigated under different conditions. The results indicated that the rebinding capacity of MIP for BSA reached 56.32 mg/g, which was 2.65 times of NIP. The non-woven polypropylene grafted BSA-imprinted polysiloxane could recognize the template protein and the selectivity factor (β) was above 2.4 when using ovalbumin, hemoglobin and γ-globulin as control proteins. The PP-g-CaSiO3@SiO2 MIP has favorable reusability. PMID:25726930

  11. Determination of simvastatin, pravastatin sodium and rosuvastatin calcium in tablet dosage forms by HPTLC

    Directory of Open Access Journals (Sweden)

    Chaudhari B

    2007-01-01

    Full Text Available Simple and reproducible HPTLC method was developed for the separation and quantitation of simvastatin, pravastatin sodium and rosuvastatin calcium, cholesterol lowering agents in pharmaceutical dosage forms. The stationary phase used was precoated silica gel 60F 254 . The mobile phase used was a mixture of chloroform:methanol:toluene (6:2:2, v/v/v. The method has been completely validated and proved to be rugged. Calibration curves were linear over the studied ranges with correlation coefficients grater than 0.999. All the drugs were extracted from the respective tablets using methanol. The percentage recoveries ranged from 100 to 101 for simvastatin, 98 to 101 for pravastatin sodium and 98 to 102 for rosuvastatin calcium. The LOD for simvastatin, pravastatin sodium and rosuvastatin calcium were found to be 15, 9 and 8 ng/spot, respectively and LOQ were 200 ng/spot for simvastatin and 100 ng/spot for pravastatin sodium and rosuvastatin calcium. The method can be useful in the quality control of bulk manufacturing and tablet dosage forms.

  12. Preparation and Characterization of Ni-Doped Calcium Silicate Hydrate Based on Steel Slag: Adsorption Capacity for Rhodamine B from Aqueous Solution

    OpenAIRE

    2015-01-01

    Calcium silicate hydrate based on steel slag (SCSH) and Ni-doped SCSH (NSCSH) were synthesized under specific hydrothermal conditions at saturated vapor pressure and 185°C for 7 hours. The structure and morphology of SCSH and NSCSH were characterized by XRD, SEM, and N2 adsorption/desorption. SCSH mainly consisted of amorphous calcium silicate hydrate gel (C-S-H gel) together with some flake-like tobermorite and NSCSH consisted of crystalline tobermorite and xonotlite. The addition of Ni(NO3)...

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

    Science.gov (United States)

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

    2012-02-01

    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-tetramethylbutyl)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.

  14. Continuous production of biodiesel from cottonseed oil and methanol using a column reactor packed with calcined sodium silicate base catalyst☆

    Institute of Scientific and Technical Information of China (English)

    Xia Gui; Sichen Chen; Zhi Yun

    2016-01-01

    Sodium silicate and that calcined at 400 °C for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate (CSS) catalyst exhibited much higher catalytic activity and stability. A maximum biodiesel yield of 98.9%was achieved at methanol/oil mole ratio of 12:1, reaction temperature 65 °C, reaction time 3.0 h, and CSS/oil mass ratio of 2 wt%. After 7 consecutive reactions without any treatment, biodiesel yield reduced to 82.5%. Considering technological and economic feasibility, CSS base catalyst supported onθrings was prepared for continuous transesterification. The maximum yield was 99.1%under optimum conditions (reaction temperature 55 °C, methanol velocity 1 ml·min−1, oil velocity 3 ml·min−1, and 5 tower sec-tions). These results indicate that this new continuous biodiesel production process and apparatus present a great potential for industrial application in biodiesel.

  15. Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

    Energy Technology Data Exchange (ETDEWEB)

    Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it [Dipartimento di Ingegneria " Enzo Ferrari" , Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy); Romagnoli, Marcello [Dipartimento di Ingegneria " Enzo Ferrari" , Università degli studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41125 Modena (Italy); Pollastri, Simone; Gualtieri, Alessandro F. [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, Via S. Eufemia 19I, I-41121 Modena (Italy)

    2015-01-15

    Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed.

  16. Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

    International Nuclear Information System (INIS)

    Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for construction purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed

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

    Science.gov (United States)

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

    1990-06-01

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

  18. Physical properties of sodium silicate based silica aerogels prepared by single step sol-gel process dried at ambient pressure

    International Nuclear Information System (INIS)

    The experimental results on physical properties of water glass (sodium silicate) based silica aerogels prepared by single step sol-gel process, dried at atmospheric pressure are reported. The hydrolysis and condensation reactions of the sodium silicate precursor proceeded with tartaric acid as a catalyst. The hydrogel was vapour passed in order to remove sodium salt from the gel network. Solvent exchange was carried out using methanol and hexane as a solvents. Finally, surface chemical modification of the gel was done using trimethylchlorosilane (TMCS) followed by ambient pressure drying of the gel up to the temperature 200 deg. C. To get good quality aerogels various sol-gel parameters such as water vapour passing period varied from 0.5 to 2 h, gel aging from 1 to 4 h, Na2SiO3/H2O molar ratio from 3 x 10-3 to 1.5 x 10-2, tartaric acid/Na2SiO3 molar ratio from 0.3 to 1.9 and TMCS/Na2SiO3 molar ratio from 4.8 to 12. The aerogels were characterized by percentage of volume shrinkage, bulk density, porosity and hydrophobicity. The hydrophobicity of the aerogel was confirmed by Fourier Transform Infrared (FTIR) Spectroscopy and contact angle measurements. Microstructural studies have been carried out by Scanning Electron Microscopy (SEM) and nitrogen adsorption BET analysis. From the TGA-DTA studies of the aerogels, it was found that the aerogels were thermally stable up to 470 oC. Low density (∼0.066 g/cm3), high hydrophobicity (∼145 deg.), high porosity (∼97 %), high pore volume, surface area of 510 m2/g aerogels have been obtained for Na2SiO3:H2O:tartaric acid (C4H6O6):TMCS molar ratio at 1:166.6:2.5:12 respectively with half an hour water vapour passing.

  19. Formation of Na1+xV3O8 Nanoribbon Thin Film from V2O5 Xerogel on Sodium Silicate Glass Substrate

    Institute of Scientific and Technical Information of China (English)

    GUO Yi; XU Jin-jie; LI Jun; YANG Wen-sheng

    2007-01-01

    Na1+xV3O8 nanoribbon thin film was successfully fabricated by annealing the V2O5 xerogel film on sodium silicate glass substrate at 450 ℃. It has been identified that the amount of sodium ions diffused into the V2O5 xerogel film increases with the high temperature of annealing treatment. The sodium glass substrate serves as a limited sodium source to induce the transformation from V2O5 to Na1+xV3O8.

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

    Science.gov (United States)

    Matsui, Masaki; Mizukoshi, Fumikazu; Imanishi, Nobuyuki

    2015-04-01

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

  1. Spontaneous and CRH-Induced Excitability and Calcium Signaling in Mice Corticotrophs Involves Sodium, Calcium, and Cation-Conducting Channels

    Czech Academy of Sciences Publication Activity Database

    Zemková, Hana; Tomič, M.; Kučka, M.; Aguilera, G.; Stojilkovic, S. S.

    2016-01-01

    Roč. 157, č. 4 (2016), s. 1576-1589. ISSN 0013-7227 R&D Projects: GA ČR(CZ) GBP304/12/G069; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : action potential * background sodium conductance * bursting activity * cation-conducting channels * cytosolic calcium concentration * resting membrane potential Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 4.503, year: 2014

  2. Characterisation and determination of the neutron transmission properties of sodium-calcium and sodium borates from different regions in Turkey

    International Nuclear Information System (INIS)

    In this study, ulexite, probertite found within sodium-calcium borates and borax, and tincalconite found within sodium borates retrieved from different regions in Turkey are evaluated for their neutron irradiation performances. Characterisations were performed using XRD, FT-IR, Raman spectroscopy. B2O3 contents were determined experimentally, structural water contents and surface morphologies were determined using DTA/TG and SEM. Neutron transmission values and total macroscopic cross-sections were determined using 239Pu-Be source moderated in a howitzer. Neutron transmission values from lowest to highest were found to be as follows: secondary ulexite (Kirka), tincalconite (Kirka), ulexite (Kestelek), ulexite (Kirka), borax (Kirka), probertite (Kestelek) and ulexite (Bigadic). (author)

  3. Effect of calcium/sodium ion exchange on the osmotic properties and structure of polyelectrolyte gels.

    Science.gov (United States)

    Horkay, Ferenc; Basser, Peter J; Hecht, Anne-Marie; Geissler, Erik

    2015-12-01

    We discuss the main findings of a long-term research program exploring the consequences of sodium/calcium ion exchange on the macroscopic osmotic and elastic properties, and the microscopic structure of representative synthetic polyelectrolyte (sodium polyacrylate, (polyacrylic acid)) and biopolymer gels (DNA). A common feature of these gels is that above a threshold calcium ion concentration, they exhibit a reversible volume phase transition. At the macroscopic level, the concentration dependence of the osmotic pressure shows that calcium ions influence primarily the third-order interaction term in the Flory-Huggins model of polymer solutions. Mechanical tests reveal that the elastic modulus is practically unaffected by the presence of calcium ions, indicating that ion bridging does not create permanent cross-links. At the microscopic level, small-angle neutron scattering shows that polyacrylic acid and DNA gels exhibit qualitatively similar structural features in spite of important differences (e.g. chain flexibility and chemical composition) between the two polymers. The main effect of calcium ions is that the neutron scattering intensity increases due to the decrease in the osmotic modulus. At the level of the counterion cloud around dissolved macroions, anomalous small-angle X-ray scattering measurements made on DNA indicate that divalent ions form a cylindrical sheath enveloping the chain, but they are not localized. Small-angle neutron scattering and small-angle X-ray scattering provide complementary information on the structure and interactions in polymer solutions and gels. PMID:26614803

  4. Calcium silicate structure and carbonation shrinkage of a tobermorite-based material

    International Nuclear Information System (INIS)

    Carbonated autoclaved aerated concretes (AACs) show no shrinkage at a degree of carbonation approximately less than 20%. The 29Si MAS NMR spectrum showed that at a degree of carbonation less than 25%, the typical double-chain silicate anion structure of tobermorite-11A was well maintained and interlayer Ca ions were exchanged with protons. This corresponded to the absence of carbonation shrinkage at a degree of carbonation less than 20%. When the degree of carbonation increased from 25% to 50% up to 60%, the double-chain silicate anion structure of tobermorite-11A was decomposed and Ca ions in the Ca-O layers were dissolved, showing a possible mechanism of carbonation shrinkage

  5. Influence of sodium pentosan polysulphate and certain inhibitors on calcium oxalate crystal growth.

    Science.gov (United States)

    Senthil, D; Subha, K; Saravanan, N; Varalakshmi, P

    1996-03-01

    Calcium oxalate crystal growth and aggregation leads to the formation of renal calculi. It is known to be inhibited by several compounds both in vitro and in vivo conditions. The present study highlights the inhibitory potential of sodium pentosan polysulphate (SPP), a semi-synthetic glycosaminoglycan (GAG) on calcium oxalate crystal growth in vitro. Its efficacy was compared with those of known inhibitors like pyrophosphate, heparin and chondroitin-4-sulphate. Of the above compounds pyrophosphate was found to be the most potent inhibitor. Among the GAGs, SPP exhibited 80% inhibitory activity as compared to heparin. A lesser degree of inhibition was observed with chondroitin-4-sulphate. PMID:8709973

  6. Indium sulfide precipitation from hydrochloric acid solutions of calcium and sodium chlorides

    International Nuclear Information System (INIS)

    The effect of precipitation duration, acid concentration, indium complexing with chloride ions on the process of indium sulfide chemical precipitation in hydrochloric acid solutions, precipitate composition and dispersity are studied. It is established that indium sulfide solubility increases in solutions with acid concentration exceeding 0.40-0.45 mol/l. Calcium and indium chloride addition to diluted hydrochloric solutions greatly increases the solubility of indium sulfide. The effect of calcium chloride on In2S3 solubility is higher than that of sodium chloride

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

    Science.gov (United States)

    Taylor, Joshua J; Sigmund, Wolfgang M

    2010-01-15

    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

  8. Preparation and characterization of bioactive and degradable composites containing ordered mesoporous calcium-magnesium silicate and poly(L-lactide)

    International Nuclear Information System (INIS)

    Highlights: • Mesoporous calcium-magnesium silicate and poly(L-lactide) composite was fabricated. • The composite has good hydrophilicity, in vitro degradation and bioactivity. • The composite could support cell attachment, proliferation and differentiation. - Abstract: Polylactide (PLA) and its copolymers have been widely used for bone tissue regeneration. In this study, a bioactive composite of ordered mesoporous calcium–magnesium silicate (m-CMS) and poly(L-lactide) (PLLA) was fabricated by melt blending method. The results indicated that the m-CMS particles were entrapped by polymer phase, and crystallinity of PLLA significantly decreased while the thermal stability of the m-CMS/PLLA composites was not obviously affected by addition of the m-CMS into PLLA. In addition, compared to PLLA, incorporation of the m-CMS into PLLA significantly improved the hydrophilicity, in vitro degradability and bioactivity (apatite-formation ability) of the m-CMS/PLLA composite, which were m-CMS content dependent. Moreover, it was found that incorporation of the m-CMS into PLLA could neutralize the acidic degradation by-products and thus compensated for the decrease of pH value. In cell culture experiments, the results showed that the composite enhanced attachment, proliferation and alkaline phosphatase activity (ALP) of MC3T3-E1 cells, which were m-CMS content dependent. The results indicated that the addition of bioactive materials to PLLA could result in a composite with improved properties of hydrophilicity, degradability, bioactivity and cytocompatibility

  9. Preparation and characterization of bioactive and degradable composites containing ordered mesoporous calcium-magnesium silicate and poly(L-lactide)

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Jiajin [Key Shanghai Key Laboratory of Advanced Polymeric Materials, East China University of Science and Technology, Shanghai 200237 (China); Dong, Xieping, E-mail: jxzhyxh@163.com [Department of Orthopaedic Surgery, Jiangxi People' s Hospital, Nanchang 330006 (China); Ma, Xuhui [Polymer Science (Shenzhen) New Materials Co., Ltd., Shenzhen 518101 (China); Tang, Songchao, E-mail: schtang@ecust.edu.cn [Key Shanghai Key Laboratory of Advanced Polymeric Materials, East China University of Science and Technology, Shanghai 200237 (China); Wu, Zhaoying; Xia, Ji; Wang, Quanxiang; Wang, Yutao; Wei, Jie [Key Shanghai Key Laboratory of Advanced Polymeric Materials, East China University of Science and Technology, Shanghai 200237 (China)

    2014-10-30

    Highlights: • Mesoporous calcium-magnesium silicate and poly(L-lactide) composite was fabricated. • The composite has good hydrophilicity, in vitro degradation and bioactivity. • The composite could support cell attachment, proliferation and differentiation. - Abstract: Polylactide (PLA) and its copolymers have been widely used for bone tissue regeneration. In this study, a bioactive composite of ordered mesoporous calcium–magnesium silicate (m-CMS) and poly(L-lactide) (PLLA) was fabricated by melt blending method. The results indicated that the m-CMS particles were entrapped by polymer phase, and crystallinity of PLLA significantly decreased while the thermal stability of the m-CMS/PLLA composites was not obviously affected by addition of the m-CMS into PLLA. In addition, compared to PLLA, incorporation of the m-CMS into PLLA significantly improved the hydrophilicity, in vitro degradability and bioactivity (apatite-formation ability) of the m-CMS/PLLA composite, which were m-CMS content dependent. Moreover, it was found that incorporation of the m-CMS into PLLA could neutralize the acidic degradation by-products and thus compensated for the decrease of pH value. In cell culture experiments, the results showed that the composite enhanced attachment, proliferation and alkaline phosphatase activity (ALP) of MC3T3-E1 cells, which were m-CMS content dependent. The results indicated that the addition of bioactive materials to PLLA could result in a composite with improved properties of hydrophilicity, degradability, bioactivity and cytocompatibility.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-01

    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

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

    Directory of Open Access Journals (Sweden)

    Gasser Andreas

    2010-11-01

    Full Text Available Abstract 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.

  12. Collapse of sodium polyacrylate chains in calcium salt solutions

    Science.gov (United States)

    Schweins, R.; Huber, K.

    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.

  13. Effect of different concentrations of potassium silicate, nano-silicon and calcium chloride on concentration of potassium, calcium and magnesium, chlorophyll content and number of florets of Asiatic lily cv. ‘Brunello’

    OpenAIRE

    N. Mirabbasi; A. Nikbakht; N. Etemadi; M.R. Sabzalian

    2013-01-01

    Production of many cut flowers, such as lilium, is very common in Iran. Flower quality has special importance in lilium flower production process, and proper nutrition is one of the major effective factors. This research was conducted to investigate the effect of different concentrations of potassium silicate, nano-silicon and calcium chloride on concentration of potassium, calcium and magnesium, chlorophyll index and number of florets of Asiatic lily 'Brunello'. The experiment was carried ou...

  14. The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium: A study from ash evaporating to condensing

    International Nuclear Information System (INIS)

    The high contents of sodium and calcium in Zhundong coal induce severe slagging and ash deposition in boilers. In this study, the ash deposition mechanism was investigated based on the results obtained from a full-scale boiler (350 MW) burning Zhundong coal, and a fixed bed reactor used for ash evaporating-condensing. In the full-scale boiler, the condensing and depositing of sodium and calcium sulfates play an important role on ash depositing on convection heating surfaces. Sulfates start to significantly condense and deposit at the flue gas temperature of about 850 °C on the medium and high temperature reheater surfaces. Ash evaporating tests proved that, with the increasing in temperature from 400 °C to 1200 °C, the ash evaporating process is divided into three stages: 1) 400–800 °C, 80% of sodium, and 100% of chlorine are released; 2) 800–1000 °C, all the left sodium evaporates and sulfur starts to be released with the formation of partial aluminosilicates; 3) 1000–1200 °C, all the left sulfur is released through the decomposition of calcium sulfates and then calcium starts to evaporate, while silicon oxides disappear due to the formation of new complex silicates. Ash condensing tests further proved that, the sodium in Zhundong coal was released mainly in the forms of atom, oxide, and chloride, in which sodium chloride account for about 50%. When the evaporating temperature increased higher than 1000 °C, partial alkali and alkaline earth metals were released as gaseous sulfates, and afterward condense and deposit on the heating surfaces. At last, a temperature-dependent ash deposition mechanism in Zhundong coal combustion was proposed. - Highlights: • The ash deposition of coal with high Na/Ca content was studied in full-scale and lab-scale furnaces. • The deposition mechanism was demonstrated from ash evaporating to condensing. • Sulfate condensing at about 850 °C plays an important role in ash deposition of Zhundong coal. • A

  15. The influence of calcium magnesium, and sodium on the spectrographic analysis of natural waters

    International Nuclear Information System (INIS)

    The influences of 1000 μg/ml of calcium and sodium and 300 μg/ml of magnesium, on the spectrographic determination of Al, Ba, Cr, Fe, Li , Mn, Ni, Pb, Sr and Ti, minor constituents in natural waters, have been studied, In order to eliminate them, the elements Ga, In, La, Ti and Zn, as well as a mixture containing 30 % Tl-70 % In, have been tested as spectrochemical buffers. (Author) 7 refs

  16. Effects of surface application of calcium-magnesium silicate and gypsum on soil fertility and sugarcane yield

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre Costa Crusciol

    2014-12-01

    Full Text Available Lime application recommendations for amendment of soil acidity in sugarcane were developed with a burnt cane harvesting system in mind. Sugarcane is now harvested in most areas without burning, and lime application for amendment of soil acidity in this system in which the sugarcane crop residue remains on the ground has been carried out without a scientific basis. The aim of this study was to evaluate the changes in soil acidity and stalk and sugar yield with different rates of surface application of calcium, magnesium silicate, and gypsum in ratoon cane. The experiment was performed after the 3rd harvest of the variety SP 81-3250 in a commercial green sugarcane plantation of the São Luiz Sugar Mill (47º 25' 33" W; 21º 59' 46" S, located in Pirassununga, São Paulo, in southeast Brazil. A factorial arrangement of four Ca-Mg silicate rates (0, 850, 1700, and 3400 kg ha-1 and two gypsum rates (0 and 1700 kg ha-1 was used in the experiment. After 12 months, the experiment was harvested and technological measurements of stalk and sugar yield were made. After harvest, soil samples were taken at the depths of 0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m in all plots, and the following determinations were made: soil pH in CaCl2, organic matter, P, S, K, Ca, Mg, H+Al, Al, Si, and base saturation. The results show that the application of gypsum reduced the exchangeable Al3+ content and Al saturation below 0.05 m, and increased the Ca2+ concentration in the whole profile, the Mg2+ content below 0.10 m, K+ below 0.4 m, and base saturation below 0.20 m. This contributed to the effect of surface application of silicate on amendment of soil acidity reaching deeper layers. From the results of this study, it may be concluded that the silicate rate recommended may be too low, since the greater rates used in this experiment showed greater reduction in soil acidity, higher levels of nutrients at greater depths and an increase in stalk and sugar

  17. Application of reference point indentation for micro-mechanical surface characterization of calcium silicate based dental materials.

    Science.gov (United States)

    Antonijević, Djordje; Milovanović, Petar; Riedel, Christoph; Hahn, Michael; Amling, Michael; Busse, Björn; Djurić, Marija

    2016-04-01

    The objective of this study was to elucidate micromechanical properties of Biodentine and two experimental calcium silicate cements (CSCs) using Reference Point Indentation (RPI). Biomechanical characteristics of the cement type and the effects of a radiopacifier, liquid components, acid etching treatment and bioactivation in simulated body fluid (SBF) were investigated by measuring the microhardness, average unloading slope (Avg US) and indentation distance increase (IDI). Biodentine had a greater microhardness than the experimental CSCs, while the Avg US and IDI values were not significantly different among investigated materials. There was a statistically significant difference in microhardness and IDI values between pure CSCs and radiopacified cements (p < 0.05). Micromechanical properties were not affected by different liquid components used. Acid-etching treatment reduced Biodentine's microhardness while cements' immersion in SBF resulted in greater microhardness and higher IDI values compared to the control group. Clearly, the physiological environment and the cements' composition affect their surface micromechanical properties. The addition of calcium chloride and CSCs' immersion in SBF are beneficial for CSCs' micromechanical performance, while the addition of radiopacifiers and acid etching treatment weaken the CSCs' surface. Application of RPI aids with the characterization of micromechanical properties of synthetic materials' surfaces. PMID:26888441

  18. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    International Nuclear Information System (INIS)

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorly crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay

  19. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    Energy Technology Data Exchange (ETDEWEB)

    Champenois, Jean-Baptiste; Dhoury, Mélanie [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Mercier, Cyrille [LMCPA, Université de Valenciennes et du Hainaut Cambrésis, 59600 Maubeuge (France); Revel, Bertrand [Centre Commun de Mesure RMN, Université Lille1 Sciences Technologies, Cité Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Le Bescop, Patrick [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Damidot, Denis [Ecole des Mines de Douai, LGCgE-GCE, 59508 Douai (France)

    2015-04-15

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorly crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.

  20. Characterization of silicates and calcium carbonates applied to high-dose dosimetry

    International Nuclear Information System (INIS)

    The predominant isomorphous form in the biominerals studied in this work (oyster shell, coral, mother of pearl and shell) was aragonite. The appearance of the calcite phase occurred at 500 deg C at a heating rate of 10 deg C/s for all samples except for the coral sample, which was 400 deg C, independent of the heating rate. The most abundant element in the biominerals samples was Ca in the CaO form, and in the silicates (tremolite, diopside and rhodonite) Si in the SiO form. The most common trace element observed in the biominerals samples was Fe. The analyses of electron paramagnetic resonance showed lines of Mn2+ in the coral and mother-of-pearl samples before irradiation. In the case of the irradiated samples, the defects found were CO2-, CO33-, CO3- and SO2-, in the g range between 2.0010 and 2.0062. In the analyses by optical absorption of biominerals, transitions due to the presence of Mn in the samples were found. A thermoluminescent (TL) peak at approximately 140 deg C was found for the biominerals and at 180 deg C for silicates, which intensity depends directly on the dose. For samples exposed to different types of radiation, the TL peak occurred at lower temperatures. From the dose-response curves obtained for these materials, it was possible to determine a linear range for which their application in high dose dosimetry becomes possible. Taking into account the radiation type, among biominerals and silicates, the lowest detectable dose (40mGy) to gamma radiation was achieved for oyster shell samples using the measuring technique of optically stimulated luminescence (OSL). Using beta radiation, for diopside and tremolite samples the lowest detectable dose of 60mGy was obtained. For all samples, using the TL, OSL and thermally stimulated exoelectron emission (TSEE) techniques in alpha, beta and gamma radiation beans a good response reproducibility was obtained. Therefore, the samples characterized in this work are suitable to be used as high dose detectors

  1. Effects of surface application of dolomitic limestone and calcium-magnesium silicate on soybean and maize in rotation with green manure in a tropical region

    Directory of Open Access Journals (Sweden)

    Gustavo Spadotti Amaral Castro

    2015-01-01

    Full Text Available Although lime is currently the material most frequently used to ameliorate soil acidity in Brazil, silicate could efficiently replace this source because of its greater solubility and its greater silicon content, which are beneficial for plant development. This study aimed to evaluate the effects of superficial lime and silicate application on soil chemical attributes as well as on soybean and maize nutrition and grain yields when these crops are grown in rotation with green manure. The experimental design was a complete randomized block with sixteen replicates. Plots were treated with one of two materials for acidity correction (dolomitic lime and calcium/magnesium silicate or with no soil correction, as a control. Silicate corrected soil acidity and increased exchangeable base levels in soil at greater depths faster than does liming. The application of both acidity-correcting materials increased N, Ca and Mg leaf concentrations, and all yield components and grain yield in soybean; but in maize, just silicate also increased N and Si when compared with lime, whereas both acidity-correcting increased just two yield components: grains per ear and mass of 100 grains, resulting in highest grain yield. The application of both acidity-correcting materials increased dry matter production of green manures, but for pigeon pea the silicate provided the best result in this dry-winter region.

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

    Science.gov (United States)

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

    2013-11-01

    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 Qf at its selectivity filter. We are thus able to reconcile the discrete calcium conduction bands recently revealed in our BD simulations, M0 (Qf=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 Qf for the sodium-calcium channels family. An increase of Qf 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 Qf(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 Ca2+/Na+ valence selectivity of calcium and sodium ion channels. The model and results could be also applicable to biomimetic nanopores with charged walls.

  3. Mechanistic study and modeling of radionuclides retention by the hydrated calcium silicates (HCS) of cements; Etude mecanistique et modelisation de la retention de radionucleides par les silicates de calcium hydrates (CSH) des ciments

    Energy Technology Data Exchange (ETDEWEB)

    Pointeau, I

    2000-09-01

    This work attempts to investigate the modelling of radioisotopes (Cs{sup +}, Pb{sup 2+}, Eu{sup 3+}) immobilization in cement matrix, in the frame of the design of engineered barrier of a deep radwaste repository. The model development concept consists of three major steps: - surface chemistry modelling of the calcium silicate hydrate CSH, used to simulate hydrated cement behaviour; - solid analysis of the batch sorption experiments: identification of the uptake mechanism; - both previous steps are used, with isotherm data, in the modelling of the radioisotopes immobilization in the CSH matrix. Final results: (all modelling are available for all the range of studied Ca/Si ratios and have been validated with predictive calculations). - A thermodynamic modelling of the CSH surface chemistry has been developed. The labile calcium and proton sorption constants on silanol sites (>SiOH) have been extracted. - Cs{sup +} is sorbed on two sites. The silanol site (weak site) has a high site density (10 sites.nm{sup -2}), which accounts for the CSH unsaturation in high [CS{sup +}]. A strong site is also identified. - Pb{sup 2+} immobilization in CSH matrix is modelled with surface equilibria and solubility equilibrium. - Eu{sup 3+} fixation has been investigated with solid analysis: Site-Selective anti Time-Resolved Luminescence Spectroscopy, XPS and SEM-EDS. Eu{sup 3+} thus does not precipitate in CSH water but is sorbed on the CSH surface (high hydroxylated environment). Europium is also (minority site) inserted in the CSH framework. (author)

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

    International Nuclear Information System (INIS)

    The structure of nanocrystalline calcium silicate hydrates (C-S-H) was studied using X-ray diffraction and literature data. It is proposed that C-S-H of Ca/Si ratio ranging between ∼ 0.6 and ∼ 1.7 can be described as nanocrystalline tobermorite affected by turbostratic disorder. The broadening and shift of the basal reflection positioned between ∼ 13.5 and ∼ 11.2 Å (depending on the Ca/Si ratio) arises from nanocrystallinity and possibly from an interstratification phenomenon. 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 Å 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 Å 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 Å, respectively

  5. The Role of an Impurity in Ceftriaxone Sodium Preparation for Injection in Determining Compatibility with Calcium-Containing Solutions.

    Science.gov (United States)

    Tange, Mio; Yoshida, Miyako; Nakai, Yuka; Uchida, Takahiro

    2016-01-01

    Ceftriaxone sodium preparation for injection is known to form insoluble microparticles with calcium. The purpose of this study was to evaluate the role of an impurity in the ceftriaxone sodium preparation on this incompatibility. Firstly, using HPLC, two impurities were identified in the ceftriaxone sodium solution. The major impurity (impurity 1) was identified as tetrahydro-2-methyl-3-thioxo-1,2,4-triazine-5,6-dione by LC/MS. Secondly, the role played by this impurity in the incompatibility with calcium was examined. Using seven different ceftriaxone preparations for injection, the effect of adding impurity 1 to mixed solutions of ceftriaxone sodium and calcium chloride on the appearance of insoluble microparticles, was examined using a light obscuration particle counter. Although incompatibility was not completely suppressed by the addition of impurity 1, the number of insoluble microparticles formed with calcium chloride solution was decreased in proportion to the concentration of impurity 1, and the concentration of calcium ion decreased as the concentration of added impurity 1 increased. These results show that impurity 1 plays a concentration-dependent role in incompatibility between ceftriaxone sodium preparation for injection and calcium-containing solutions. PMID:26936047

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

    International Nuclear Information System (INIS)

    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

  7. Clarification of sodium silicate solutions derived from diatomites, to improve their industrial expectations

    International Nuclear Information System (INIS)

    solutions of soluble silicates synthesized have been clarified in Costa Rica from diatomite in almost 50% of their initial coloration. Clarification and removal of iron oxides have been achieved in a higher order of 50% m/m expressed as Fe2 O3. Activated carbon treatment has clarified the scope of [31-57]%, but not significantly decreases the iron content. The application of NaClO to 3% m/m clarifies the scope of [28-51]%, and reduced iron by 48% m/m. The land alone has been shown that is not very effective filter to clarify, [0-14]%, but is effective for the stripping of iron by 68% m/m. Other procedures are effective in clarifying the scope of [42-51]% and reduced the amount of iron in the field of [48-66]%. The synthesis of soluble glasses is possible to clarify for conditioning with commercial purposes diverse, treatment methodologies and analytical control, simple and economical. (author)

  8. Odontogenic differentiation of human dental pulp cells by calcium silicate materials stimulating via FGFR/ERK signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chao-Hsin [School of Dentistry, Chung Shan Medical University, Taichung City, Taiwan (China); Hung, Chi-Jr; Huang, Tsui-Hsien [School of Dentistry, Chung Shan Medical University, Taichung City, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung City, Taiwan (China); Lin, Chi-Chang [Department of Chemical and Materials Engineering, Tunghai University, Taichung City, Taiwan (China); Kao, Chia-Tze [School of Dentistry, Chung Shan Medical University, Taichung City, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung City, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [Department of Chemical and Materials Engineering, Tunghai University, Taichung City, Taiwan (China)

    2014-10-01

    Bone healing needs a complex interaction of growth factors that establishes an environment for efficient bone formation. We examine how calcium silicate (CS) and tricalcium phosphate (β-TCP) cements influence the behavior of human dental pulp cells (hDPCs) through fibroblast growth factor receptor (FGFR) and active MAPK pathways, in particular ERK. The hDPCs are cultured with β-TCP and CS, after which the cells' viability and odontogenic differentiation markers are determined by using PrestoBlue® assay and western blot, respectively. The effect of small interfering RNA (siRNA) transfection targeting FGFR was also evaluated. The results showed that CS promoted cell proliferation and enhances FGFR expression. It was also found that CS increases ERK and p38 activity in hDPCs, and furthermore, raises the expression and secretion of DSP, and DMP-1. Additionally, statistically significant differences (p < 0.05) have been found in the calcium deposition in si-FGFR transfection and ERK inhibitor between CS and β-TCP; these variations indicated that ERK/MAPK signaling is involved in the silicon-induced odontogenic differentiation of hDPCs. The current study shows that CS substrates play a key role in odontoblastic differentiation of hDPCs through FGFR and modulate ERK/MAPK activation. - Highlights: • CS influences the behavior of hDPCs through fibroblast growth factor receptor. • CS increases ERK and p38 activity in hDPCs. • ERK/MAPK signaling is involved in the Si-induced odontogenic differentiation of hDPCs. • Ca staining shows that FGFR regulates hDPC differentiation on CS, but not on β-TCP.

  9. Odontogenic differentiation of human dental pulp cells by calcium silicate materials stimulating via FGFR/ERK signaling pathway

    International Nuclear Information System (INIS)

    Bone healing needs a complex interaction of growth factors that establishes an environment for efficient bone formation. We examine how calcium silicate (CS) and tricalcium phosphate (β-TCP) cements influence the behavior of human dental pulp cells (hDPCs) through fibroblast growth factor receptor (FGFR) and active MAPK pathways, in particular ERK. The hDPCs are cultured with β-TCP and CS, after which the cells' viability and odontogenic differentiation markers are determined by using PrestoBlue® assay and western blot, respectively. The effect of small interfering RNA (siRNA) transfection targeting FGFR was also evaluated. The results showed that CS promoted cell proliferation and enhances FGFR expression. It was also found that CS increases ERK and p38 activity in hDPCs, and furthermore, raises the expression and secretion of DSP, and DMP-1. Additionally, statistically significant differences (p < 0.05) have been found in the calcium deposition in si-FGFR transfection and ERK inhibitor between CS and β-TCP; these variations indicated that ERK/MAPK signaling is involved in the silicon-induced odontogenic differentiation of hDPCs. The current study shows that CS substrates play a key role in odontoblastic differentiation of hDPCs through FGFR and modulate ERK/MAPK activation. - Highlights: • CS influences the behavior of hDPCs through fibroblast growth factor receptor. • CS increases ERK and p38 activity in hDPCs. • ERK/MAPK signaling is involved in the Si-induced odontogenic differentiation of hDPCs. • Ca staining shows that FGFR regulates hDPC differentiation on CS, but not on β-TCP

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

    Science.gov (United States)

    D'Onofrio, Cladio; Lindberg, Sylvia

    2009-11-01

    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 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

  11. Study of corrosion of sodium-zirconium-silicate glass in sodium hydroxide and sodium carbonate solutions at 90-150 deg C

    International Nuclear Information System (INIS)

    Examined are the time- and temperature dependencies of glass corrosion (glass composition: 20.48% mole Na2Ox6.65% molexZrO2x72.87% mole SiO2) in aqueous solutions of sodium hydrate and sodium carbonate with concentrations of 2g-equiv/l at 90-150 deg C. The measurements are made by two methods: estimation of glass weight losses in the course of corrosion; and estimation of the amounts of SiO2 and ZrO2 that had passed from the glass surface to the solution. Glass dissolution in NaOH was found to occur non-uniformly. Increased alkali-stability was caused not only by low ZrO2 solubility, but also by formation on the glass surface of a hydrolysis film, chiefly composed of zirconium hydroxide. A leached layer containing a considerable amount of zirconium dioxide in hydrolyzed state was noted to form on the glass surface when the glass interacted with the sodium carbonate solution. The presence of this layer made the glass increasingly resistant to sodium carbonate and had a positive effect on the kinetic characteristics of the corrosion process

  12. THERMOANALYTICAL EVENTS AND ENTHALPIES OF SELECTED PHASES AND SYSTEMS OF THE CHEMISTRY AND TECHNOLOGY OF CONCRETE PART I. CALCIUM-SILICATE-ALUMINATE-SULFATE HYDRATES

    OpenAIRE

    Milan Drabik; Lubica Galikova; Scholtzova Eva; Hadzimova Eva

    2014-01-01

    Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - (delta)H, of natural minerals of calcium-silicate-sulfate-aluminate hydrates. The thermoanalytical curves of thaumasite and ettringite are fully in line with that reported in reference sources. The values of (delta)H calculated from DSC curves in the intervals of key decomposition steps ranging from 50 to 250 C, achieve (1215 +/- 60) J g-1 for thaumasite and (930 +/- 40) J g...

  13. Present and future of glass-ionomers and calcium-silicate cements as bioactive materials in dentistry: Biophotonics-based interfacial analyses in health and disease

    OpenAIRE

    Watson, Timothy F; Atmeh, Amre R.; Sajini, Shara; Cook, Richard J.; Festy, Frederic

    2014-01-01

    Objective Since their introduction, calcium silicate cements have primarily found use as endodontic sealers, due to long setting times. While similar in chemistry, recent variations such as constituent proportions, purities and manufacturing processes mandate a critical understanding of service behavior differences of the new coronal restorative material variants. Of particular relevance to minimally invasive philosophies is the potential for ion supply, from initial hydration to mature set i...

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

    Directory of Open Access Journals (Sweden)

    GeorgeEBillman

    2011-02-01

    Full Text Available 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 min. 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-wk exercise training (progressively increasing treadmill running (S n = 9; R n = 8 or 10-wk sedentary (S n = 14; R n = 5 groups. At the end of the 10-wk 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<0.05 higher in susceptible compared to resistant dogs. In contrast, NCX1 levels were similar in the exercise trained resistant and susceptible animals. Conclusion: These data suggest that exercise training can restore a more normal NCX1 level in dogs susceptible to ventricular fibrillation, improving cystolic calcium regulation and could thereby reduce the risk for sudden death following myocardial infarction.

  15. Biological Assessment of a Calcium Silicate Incorporated Hydroxyapatite-Gelatin Nanocomposite: A Comparison to Decellularized Bone Matrix

    Directory of Open Access Journals (Sweden)

    Dong Joon Lee

    2014-01-01

    Full Text Available Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS. Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD. Twelve Sprague-Dawley rats were randomized to four groups: control (defect only, decellularized bone matrix (DECBM, and HGCS with and without multipotent adult progenitor cells (MAPCs. DECBM was prepared by removing all the cells using SDS and NH4OH. After 12 weeks, the CSD specimens were harvested to evaluate radiographical, histological, and histomorphometrical outcomes. The in vitro osteogenic effects of the materials were studied by focal adhesion, MTS, and alizarin red. Micro-CT analysis indicated that the DECBM and the HGCS scaffold groups developed greater radiopaque areas than the other groups. Bone regeneration, assessed using histological analysis and fluorochrome labeling, was the highest in the HGCS scaffold seeded with MAPCs. The DECBM group showed limited osteoinductivity, causing a gap between the implant and host tissue. The group grafted with HGCS+MAPCs resulting in twice as much new bone formation seems to indicate a role for effective bone regeneration. In conclusion, the novel HGCS scaffold could improve bone regeneration and is a promising carrier for stem cell-mediated bone regeneration.

  16. Biological assessment of a calcium silicate incorporated hydroxyapatite-gelatin nanocomposite: a comparison to decellularized bone matrix.

    Science.gov (United States)

    Lee, Dong Joon; Padilla, Ricardo; Zhang, He; Hu, Wei-Shou; Ko, Ching-Chang

    2014-01-01

    Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS). Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD). Twelve Sprague-Dawley rats were randomized to four groups: control (defect only), decellularized bone matrix (DECBM), and HGCS with and without multipotent adult progenitor cells (MAPCs). DECBM was prepared by removing all the cells using SDS and NH4OH. After 12 weeks, the CSD specimens were harvested to evaluate radiographical, histological, and histomorphometrical outcomes. The in vitro osteogenic effects of the materials were studied by focal adhesion, MTS, and alizarin red. Micro-CT analysis indicated that the DECBM and the HGCS scaffold groups developed greater radiopaque areas than the other groups. Bone regeneration, assessed using histological analysis and fluorochrome labeling, was the highest in the HGCS scaffold seeded with MAPCs. The DECBM group showed limited osteoinductivity, causing a gap between the implant and host tissue. The group grafted with HGCS+MAPCs resulting in twice as much new bone formation seems to indicate a role for effective bone regeneration. In conclusion, the novel HGCS scaffold could improve bone regeneration and is a promising carrier for stem cell-mediated bone regeneration. PMID:25054149

  17. Anticorrosive effects and in vitro cytocompatibility of calcium silicate/zinc-doped hydroxyapatite composite coatings on titanium

    Science.gov (United States)

    Huang, Yong; Zhang, Honglei; Qiao, Haixia; Nian, Xiaofeng; Zhang, Xuejiao; Wang, Wendong; Zhang, Xiaoyun; Chang, Xiaotong; Han, Shuguang; Pang, Xiaofeng

    2015-12-01

    This work elucidated the corrosion resistance and cytocompatibility of electroplated Zn- and Si-containing bioactive calcium silicate/zinc-doped hydroxyapatite (ZnHA/CS) ceramic coatings on commercially pure titanium (CP-Ti). The formation of ZnHA/CS coating was investigated through Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray and inductively coupled plasma analyses. The XRD image showed that the reaction layer was mainly composed of HA and CaSiO3. The fabricated ZnHA/CS coatings presented a porous structure and appropriate thickness for possible applications in orthopaedic surgery. Potentiodynamic polarization tests showed that ZnHA/CS coatings exhibited higher corrosion resistance than CP-Ti. Dissolution tests on the coating also revealed that Si4+ and Zn2+ were leached at low levels. Moreover, MC3T3-E1 cells cultured on ZnHA/CS featured improved cell morphology, adhesion, spreading, proliferation and expression of alkaline phosphatase than those cultured on HA. The high cytocompatibility of ZnHA/CS could be mainly attributed to the combination of micro-porous surface effects and ion release (Zn2+ and Si4+). All these results indicate that ZnHA/CS composite-coated CP-Ti may be a potential material for orthopaedic applications.

  18. In vivo evaluation of the effects of hydraulic calcium silicate dental cements on plasma and liver aluminium levels in rats.

    Science.gov (United States)

    Demirkaya, Kadriye; Can Demirdöğen, Birsen; Öncel Torun, Zeynep; Erdem, Onur; Çetinkaya, Serdar; Akay, Cemal

    2016-02-01

    Our aim was to test whether the presence of three hydraulic calcium silicate dental cements--MTA Angelus, MTA Fillapex, and Theracal LC--in the dental extraction socket of an in vivo model, would affect the levels of aluminium (Al) in the plasma and liver. Following anesthesia, the right upper incisor of each male Wistar albino rat was extracted and polyethylene tubes filled with MTA Angelus, MTA Fillapex, or Theracal LC were inserted into the depth of the extraction socket and gingival tissue was sutured. The rats were killed 7, 30, or 60 d after the operation. Blood and liver samples were obtained from the rats before they were killed, and the levels of Al were measured by atomic absorption spectrometry. Plasma Al levels were higher in the rats in which the mineral trioxide aggregate (MTA) cements were implanted, especially MTA Angelus and MTA Fillapex, compared with control rats. In liver samples, however, the differences in Al level were not statistically significant. Our results show that Al might have been released into the circulation from the three dental cements tested, especially MTA Angelus and MTA Fillapex. Further research should be carried out on the possible biological effects of Al liberated from dental cements. PMID:26706154

  19. Push-out bond strength of MTA HP, a new high-plasticity calcium silicate-based cement.

    Science.gov (United States)

    Silva, Emmanuel Jnl; Carvalho, Nancy Kudsi; Zanon, Mayara; Senna, Plínio Mendes; DE-Deus, Gustavo; Zuolo, Mário Luis; Zaia, Alexandre Augusto

    2016-06-14

    This study was designed to investigate the resistance to dislodgment provided by MTA HP, a new high-plasticity calcium silicate-based cement. Biodentine and White MTA Angelus were used as reference materials for comparison. Three discs 1 ± 0.1 mm thick were obtained from the middle third of the roots of 5 maxillary canines. Three 0.8-mm-wide holes were drilled on the axial surface of each root disc. Standardized irrigation was performed. Then the holes were dried with paper points and filled with one of the three tested cements. The filled dental slices were immersed in a phosphate-buffered saline (PBS) solution (pH 7.2) for 7 days before the push-out assessment. The Kruskal-Wallis test was applied to assess the effect of each endodontic cement on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. All specimens had measurable push-out values and no premature failure occurred. There were significant differences among the materials (p <0.05). The Biodentine specimens had the highest push-out bond strength values (p < 0.05). MTA HP had significantly higher bond strength than White MTA (p < 0.05). MTA HP showed better push-out bond strength than its predecessor, White MTA; however, Biodentine had higher dislodgment resistance than both MTA formulations. PMID:27305515

  20. Synthesis and Enhanced Phosphate Recovery Property of Porous Calcium Silicate Hydrate Using Polyethyleneglycol as Pore-Generation Agent

    Directory of Open Access Journals (Sweden)

    Ling Pei

    2013-07-01

    Full Text Available The primary objective of this paper was to synthesize a porous calcium silicate hydrate (CSH with enhanced phosphate recovery property using polyethyleneglycol (PEG as pore-generation agent. The formation mechanism of porous CSH was proposed. PEG molecules were inserted into the void region of oxygen–silicon tetrahedron chains and the layers of CSH. A steric hindrance layer was generated to prevent the aggregation of solid particles. A porous structure was formed due to the residual space caused by the removal of PEG through incineration. This porous CSH exhibited highly enhanced solubility of Ca2+ and OH− due to the decreased particle size, declined crystalline, and increased specific surface area (SBET and pore volume. Supersaturation was increased in the wastewater with the enhanced solubility, which was beneficial to the formation of hydroxyapatite (HAP crystallization. Thus, phosphate can be recovered from wastewater by producing HAP using porous CSH as crystal seed. In addition, the regenerated phosphate-containing products (HAP can be reused to achieve sustainable utilization of phosphate. The present research could provide an effective approach for the synthesis of porous CSH and the enhancement of phosphate recovery properties for environmental applications.

  1. The Effect of Calcium Sodium Phosphosilicate on Dentin Hypersensitivity: A Systematic Review and Meta-Analysis.

    Directory of Open Access Journals (Sweden)

    Mengjiao Zhu

    Full Text Available To investigate the effect of calcium sodium phosphosilicate (CSPS in treating dentin hypersensitivity (DH and to compare this effect to that of a negative (placebo control.Several databases, including Medline, EMBASE, Web of Science, The Cochrane Library, and the Chinese Biomedical Literature Database, were searched to identify relevant articles published through January 2015; grey literature (i.e., academic literature that is not formally published was also searched. Two authors performed data extraction independently and jointly using data collection forms. The primary outcome was the DH pain response to routine activities or to thermal, tactile, evaporative, or electrical stimuli, and the secondary outcome was the side effects of CSPS use. Each study was evaluated using the Cochrane Collaboration tool for assessing risk bias. Meta-analysis of studies with the same participant demographics, interventions, controls, assessment methods and follow-up periods was performed. The Grading of Recommendations Assessment Development and Evaluation System was used to assess the quality of the evidence and the risk of bias across studies.Meta-analysis demonstrated that toothpaste containing 5% CSPS was more effective than the negative control at relieving dentin sensitivity, with the level of evidence classified as "moderate". In addition, prophylaxis paste containing 15% calcium sodium phosphosilicate was favored over the negative control at reducing post-periodontal therapy hypersensitivity, with the level of evidence categorized as "low". Only two studies reported side effects of CSPS use.The majority of studies found that calcium sodium phosphosilicate was more effective than the negative control at alleviating DH. Because strong evidence is scarce, high-quality, well-designed clinical trials are required in the future before definitive recommendations can be made.

  2. Intake of protein, calcium and sodium in public child day care centers

    OpenAIRE

    Giovana Longo-Silva; Toloni, Maysa Helena de A.; de Menezes, Risia Cristina E.; Tatiane Leocádio Temteo; Oliveira, Maria Alice A.; Leiko Asakura; Emília Chagas Costa; Taddei, José Augusto de A. C.

    2014-01-01

    OBJECTIVE: To assess calcium, protein and sodium intake, of children that attend public day-care centers and to compare it with the recommended one. METHODS: Cross-sectional descriptive study in seven public day care centers of São Paulo city, Southeast Brazil, which enrolled 366 children between 12 and 36 months of age. The data collection occurred between September and December 2010. Each day care center was evaluated for three non-consecutive days, totaling 42 days and 210 meals. Dietary i...

  3. Modifications on the properties of a calcium phosphate cement by additions of sodium alginate

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, W.T.; Fernandes, J.M.; Vieira, R.S.; Thurmer, M.B.; Santos, L.A., E-mail: trajano@ufrgs.br, E-mail: julianafernandes2@yahoo.com.br, E-mail: rsvieira.eng@gmail.com, E-mail: monicathurmer@yahoo.com.br, E-mail: luis.santos@ufrgs.br [Universidade Federal do Rio Grande do Sul (PPG/LABIOMAT/UFRGS), RS (Brazil)

    2012-07-01

    The Calcium Phosphate Cement (CPC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry due to its biocompatibility, bioactivity and osteoconductivity, and form a paste that can be easily shaped and placed into the surgical site. However, CPCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. In order to assess the strength and time to handle a CPC composed primarily of alpha phase, were added sodium alginate (1%, 2% and 3% wt) and an accelerator in an aqueous solution. The cement powder was mixed with liquid of setting, shaped into specimens and evaluated for apparent density and porosity by Archimedes method, X-ray diffraction and compressive strength. A significant increase in compressive strength by adding sodium alginate was verified. (author)

  4. Modifications on the properties of a calcium phosphate cement by additions of sodium alginate

    International Nuclear Information System (INIS)

    The Calcium Phosphate Cement (CPC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry due to its biocompatibility, bioactivity and osteoconductivity, and form a paste that can be easily shaped and placed into the surgical site. However, CPCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. In order to assess the strength and time to handle a CPC composed primarily of alpha phase, were added sodium alginate (1%, 2% and 3% wt) and an accelerator in an aqueous solution. The cement powder was mixed with liquid of setting, shaped into specimens and evaluated for apparent density and porosity by Archimedes method, X-ray diffraction and compressive strength. A significant increase in compressive strength by adding sodium alginate was verified. (author)

  5. Effect of Er2O3 dopant on electrical and optical properties of potassium sodium niobate silicate glass-ceramics

    International Nuclear Information System (INIS)

    Highlights: • The KNN–SiO2 doped Er2O3 glass-ceramics was prepared by incorporation method. • High dielectric constant (458.41 at 100 kHz) and low loss (0.0005) could be obtained. • TEM and SEM confirmed the existence of KNN crystals embedded in glass matrix. • The Er2O3 dopant causes insignificant effect on modifying Eg value. - Abstract: In this study, transparent glass-ceramics from potassium sodium niobate (KNN)-silicate glass system doped with erbium oxide (Er2O3) were successfully prepared by incorporation method. KNN was added in glass batches as heterogeneous nucleating agent. The KNN powder was mixed with SiO2 and Er2O3 dopant with KNN and Er2O3 content varied between 70–80 and 0.5–1.0 mol%, respectively. Each batch was subsequently melted at 1300 °C for 15 min in a platinum crucible using an electric furnace. The quenched glasses were then subjected to heat treatment at various temperatures for 4 h. XRD results showed that the prepared glass ceramics contained crystals of KNN solid solution. In contrary, dielectric constant (ϵr) and dielectric loss (tan δ) were found to increase with increasing heat treatment temperature. Additionally, optical properties such as absorbance and energy band gap have been investigated

  6. Sodium titanium silicate as ion exchanger: synthesis, characterization and application in separation of 90Y from 90Sr

    International Nuclear Information System (INIS)

    Full text: Solid phase extraction is a well-established sample pretreatment technique in pharmaceutical and environmental, biomedical and environmental field because it demands less organic solvents and can remove interferences and preconcentrates the objective simultaneously. There are considerable interests in developing new selective sorbents for extracting and isolating components from complicated matrices, and also for the separation of short-lived radio-nuclides from radionuclide generators in an inexpensive method. Many successful studies of site-specific monoclonal antibody labeling involving 90Y have been applied in radioimmuno-therapy. A newly designed and well characterized inorganic ion exchanger, sodium titanium silicate (Na2TiSiO5, H2O) has been employed in the separation of carrier free 90Y from its parent 90Sr from an equilibrium mixture at pH 7.0. The absorbed daughter was recovered by 1.0% EDTA solution as eluting agent successfully. The decay curve of the eluate and the Feather analysis confirmed the presence of carrier free 90Y. This material is quite stable up to 600 deg C. The study of the radiation stability of the exchanger by checking the crystallinity of the material by XRD spectra showed that the exchanger is stable up to a total dose of 64 KGy

  7. Improvement of bioactivity, degradability, and cytocompatibility of biocement by addition of mesoporous magnesium silicate into sodium-magnesium phosphate cement.

    Science.gov (United States)

    Wu, Yingyang; Tang, Xiaofeng; Chen, Jie; Tang, Tingting; Guo, Han; Tang, Songchao; Zhao, Liming; Ma, Xuhui; Hong, Hua; Wei, Jie

    2015-09-01

    A novel mesoporous magnesium-based cement (MBC) was fabricated by using the mixed powders of magnesium oxide, sodium dihydrogen phosphate, and mesoporous magnesium silicate (m-MS). The results indicate that the setting time and water absorption of the MBC increased as a function of increasing m-MS content, while compressive strength decreased. In addition, the degradability of the MBC in a solution of Tris-HCl and the ability of apatite formation on the MBC were significantly improved with the increase in m-MS content. In cell culture experiments, the results show that the attachment, proliferation, and alkaline phosphatase activity of the MC3T3-E1 cells on the MBC were significantly enhanced with the increase of the content of m-MS. It can be suggested that the MBC with good cytocompatibility could promote the proliferation and differentiation of the MC3T3-E1 cells. In short, our findings indicate that the MBC containing m-MS had promising potential as a new biocement for bone regeneration and repair applications. PMID:26395363

  8. Reuse of waste foundry sand through interaction with sodium silicate binder; Reutilizacao da areia descartada da fundicao, a partir da sua interacao com agente ligante silicato de sodio

    Energy Technology Data Exchange (ETDEWEB)

    Souza, J.C.; Chinelatto, A.S.A.; Chinelatto, A.L., E-mail: josi3souza@gmail.com [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil); Oliveira, I.L. [Universidade Tecnologica Federal do Parana (UTFPR), Ponta Grossa, PR (Brazil)

    2012-07-01

    Green sand molds are used in metal casting process. However, after heating, activated bentonite present in green sand lose the binding properties, and part of the foundry sand has to be discarded from the process. The ABNT NBR 15.984/2011 establishes the management of waste foundry sand (WFS) avoiding disposal in landfills. The objective of this work was to investigate the possibility of reusing the WFS from the study of their interaction with sodium silicate binder. Studies with silica sand and new green sand was performed to compare the results obtained with the WFS. The characterizations of the samples were performed by measures the compressive strength, X-ray diffraction, optical microscopy and scanning electron microscopy. The results showed that there is interaction of the sodium silicate with the WFS as well as with the silica sand and green sand. (author)

  9. Effects of temperature and sodium carboxylate additives on mineralization of calcium oxalate in silica gel systems

    Institute of Scientific and Technical Information of China (English)

    OUYANG; Jianming; DENG; Suiping; LI; Xiangping; TAN; Yanh

    2004-01-01

    [1]Ouyang, J. M., Yao, X. Q., Su, Z. X. et al., Simulation of calcium oxalate stone in Vitro, Science in China, Ser. B, 2003, 46(3):234-242.[2]Xu, S. H., Chen, J. Q., Zhou, H., Nepidemiological study of renal calculus in Shenshen region, Chin. J. Urol. (in Chinese), 1999,20(11): 655-657.[3]Bretherton, T., Rodgers, A., Crystallization of calcium oxalate in minimally diluted urine, J. Crystal Growth, 1998, 192: 448-455.[4]Grover, P. K., Ryall, R. L., Effect of seed crystals of uric acid and monosodium urate on the crystallization of CaOxa in undiluted human urine in vitro, Clin. Sci., 1997, 92: 205-213.[5]Laube, N., Mohr, B., Hesse, A., Laser-probe-based investigation of the evolution of particle size distributions of calcium oxalate particles formed in artificial urines, J. Crystal Growth, 2001, 233:367-374.[6]Tunik, L., Fueredi-Milhofer, H., Garti, N., Adsorption of sodium diisooctyl sulfosuccinate onto calcium oxalate crystals, Langmuir,1998, 14: 3351-3355.[7]Cody, A. M., Cody, R. D., Calcium oxalate trihydrate phase control by structurally-specific carboxylic acids, J. Cryst. Growth,1994, 135: 234-245.[8]Ouyang, J. M., Duan, L., Tieke, B., Effects of carboxylic acids on the crystal growth of calcium oxalate nanoparticles in lecithin-water liposome systems, Langmuir, 2003, 19: 8980-8985.[9]Guo, S., Ward, M. D., Wesson, J. A., Direct visualization of calcium oxalate monohydrate crystallization and dissolution with atomic force microscopy and the role of polymeric additives,Langmuir, 2002, 18:4284-4291.[10]Yasui, T., Sato, M., Fujita, K., Effects of citrate on renal stone formation and osteopontin expression in a rat urolithiasis model,Urol. Res., 2001,29: 50-56.[11]Ouyang, J. M., Deng, S. P., Controlled and uncontrolled crystallization of calcium oxalate monohydrate in the presence of citric acid, Dalton Transactions, 2003, (14): 2846-2851.[12]Khan, S. R., Whalen, P. O., Glenton, P. A., Heterogeneous nucleation of

  10. Scientific Opinion on the safety and efficacy of vitamin C (ascorbic acid, sodium ascorbate, calcium ascorbate, ascorbyl palmitate, sodium calcium ascorbyl phosphate and sodium ascorbyl phosphate) as a feed additive for all animal species based on a dossier submitted by DSM Nutritional Products Ltd

    OpenAIRE

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP)

    2013-01-01

    Vitamin C is essential for primates, guinea pigs and fish. Vitamin C, in the form of ascorbic acid and its calcium and sodium salts, ascorbyl palmitate, sodium calcium ascorbyl phosphate and sodium ascorbyl phosphate, is safe for all animal species. Setting a maximum content in feed and water for drinking is not considered necessary. Data on the vitamin C consumption of consumers are based on the levels of vitamin C in foodstuffs, including food of animal origin, produced in accordance with c...

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

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

    2012-02-21

    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

  13. Using calcium silicate to regulate the physicochemical and biological properties when using β-tricalcium phosphate as bone cement

    International Nuclear Information System (INIS)

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Regarding the formation of bone-like apatite, the diametral tensile strength as well as the ion release and weight loss of composites were compared both before and after immersions in simulated body fluid (SBF). In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on β-TCP/CS composites. The results show that the apatite deposition ability of the β-TCP/CS composites improves as the CS content is increased. For composites with more than a 60% CS content, the samples become completely covered by a dense bone-like apatite layer. At the end of the immersion period, weight losses of 24%, 32%, 34%, 38%, 41%, and 45% were observed for the composites containing 0%, 20%, 40%, 80%, 80% and 100% β-TCP cements, respectively. In addition, the antibacterial activity of CS/β-TCP composite improves as the CS-content is increased. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 60%, the quantity of cells and osteogenesis protein of hDPCs is stimulated by Si released from the β-TCP/CS composites. The degradation of β-TCP and the osteogenesis of CS give strong reason to believe that these calcium-based composite cements will prove to be effective bone repair materials. - Highlights: • CS improved the physicochemical properties and osteogenic activity of β-TCP. • Higher CS in the composite, the shorter setting time and the higher DTS was found. • With a CS more than 40%, the osteogenesis and angiogenesis proteins were promoted by

  14. Using calcium silicate to regulate the physicochemical and biological properties when using β-tricalcium phosphate as bone cement

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Chia-Tze; Huang, Tsui-Hsien [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Chen, Yi-Jyun [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Dental Department, Taichung Hospital, Ministry of Health and Welfare, Taichung City, Taiwan (China); Hung, Chi-Jr [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Lin, Chi-Chang, E-mail: chichang31@gmail.com [Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan (China)

    2014-10-01

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Regarding the formation of bone-like apatite, the diametral tensile strength as well as the ion release and weight loss of composites were compared both before and after immersions in simulated body fluid (SBF). In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on β-TCP/CS composites. The results show that the apatite deposition ability of the β-TCP/CS composites improves as the CS content is increased. For composites with more than a 60% CS content, the samples become completely covered by a dense bone-like apatite layer. At the end of the immersion period, weight losses of 24%, 32%, 34%, 38%, 41%, and 45% were observed for the composites containing 0%, 20%, 40%, 80%, 80% and 100% β-TCP cements, respectively. In addition, the antibacterial activity of CS/β-TCP composite improves as the CS-content is increased. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 60%, the quantity of cells and osteogenesis protein of hDPCs is stimulated by Si released from the β-TCP/CS composites. The degradation of β-TCP and the osteogenesis of CS give strong reason to believe that these calcium-based composite cements will prove to be effective bone repair materials. - Highlights: • CS improved the physicochemical properties and osteogenic activity of β-TCP. • Higher CS in the composite, the shorter setting time and the higher DTS was found. • With a CS more than 40%, the osteogenesis and angiogenesis proteins were promoted by

  15. Hydrothermal synthesis and characterization of Si and Sr co-substituted hydroxyapatite nanowires using strontium containing calcium silicate as precursors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Na [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhai, Dong; Chen, Lei [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Zou, Zhaoyong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Lin, Kaili, E-mail: lklsic@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Chang, Jiang, E-mail: jchang@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2014-04-01

    In the absence of any organic surfactants and solvents, the silicon (Si) and strontium (Sr) co-substituted hydroxyapatite [Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, Si/Sr-HAp] nanowires were synthesized via hydrothermal treatment of the Sr-containing calcium silicate (Sr-CS) powders as the precursors in trisodium phosphate (Na{sub 3}PO{sub 4}) aqueous solution. The morphology, phase, chemical compositions, lattice constants and the degradability of the products were characterized. The Si/Sr-HAp nanowires with diameter of about 60 nm and up to 2 μm in length were obtained after hydrothermal treatment of the Sr-CS precursors. The Sr and Si substitution amount of the HAp nanowires could be well regulated by facile tailoring the Sr substitution level of the precursors and the reaction ratio of the precursor/solution, respectively. The SiO{sub 4} tetrahedra and Sr{sup 2+} ions occupied the crystal sites of the HAp, and the lattice constants increased apparently with the increase of the substitution amount. EDS mapping also suggested the uniform distribution of Si and Sr in the synthetic nanowires. Moreover, the Si/Sr-substitution apparently improved the degradability of the HAp materials. Our study suggested that the precursor transformation method provided a facile approach to synthesize the Si/Sr co-substituted HAp nanowires with controllable substitution amount, and the synthetic Si/Sr-HAp nanowires might be used as bioactive materials for hard tissue regeneration applications. - Highlights: • Si/Sr-HAp nanowires were hydrothermally transformed from Sr{sub x}-CaSiO{sub 3} precursors. • The Si/Sr-substitution level could be facilely regulated. • The nanowire-like morphology and composition could be simultaneously regulated.

  16. The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

    Science.gov (United States)

    Hsu, T.-T.; Kao, C.-T.; Chen, Y.-W.; Huang, T.-H.; Yang, J.-J.; Shie, M.-Y.

    2015-05-01

    Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm2, and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

  17. Reproducibility of the uptake of U(VI) onto degraded cement pastes and calcium silicate hydrate phases

    International Nuclear Information System (INIS)

    The U(VI) uptake in degraded cement pastes was undertaken in the laboratories of CEA/L3MR and SUBATECH in order to check the reproducibility of the study. Two well hydrated cement pastes, CEM I (ordinary portland cement, OPC) and CEM V (blast furnace slag (BFS) and fly ash added to OPC) were degraded using similar protocols. Equilibrium solutions and solid materials were characterised for three degradation states for each paste. All samples are free of portlandite and the pH of the equilibrated cement solutions vary in the range 9.8-12.2. Three calcium silicate hydrate phases (C-S-H) were synthesised in order to compare the sorption properties of degraded cement pastes and of hydrate phases in similar pH conditions. In order to avoid precipitation processes, the operational solubility limit was evaluated before batch experiments. These solubility values vary significantly in the pH range [9-13] with a 2.4 x 10-7 mol L-1 minimum at pH close to 10.5. In batch sorption experiments, the distribution ratio Rd values are high: 3 x 104 - 1.5 x 105 mL g-1. The uptake of U(VI) increases when comparing the least and the most degraded cement pastes whereas the initial composition of cement has relatively insensitive effect. Sorption isotherms, expressed as a log [U(VI)solid]/log[U(VI)solution] plots are linear. A slope of 1 is calculated indicating the predominance of sorption processes. As sorption and desorption values are close, the uptake mechanism seems reversible. The Rd values measured in C-S-H suspensions are in good agreement with Rd values of degraded cement pastes, and C-S-H materials could be one of the cementitious phases which control U(VI) uptake in cement pastes. (orig.)

  18. Hydrothermal synthesis and characterization of Si and Sr co-substituted hydroxyapatite nanowires using strontium containing calcium silicate as precursors

    International Nuclear Information System (INIS)

    In the absence of any organic surfactants and solvents, the silicon (Si) and strontium (Sr) co-substituted hydroxyapatite [Ca10(PO4)6(OH)2, Si/Sr-HAp] nanowires were synthesized via hydrothermal treatment of the Sr-containing calcium silicate (Sr-CS) powders as the precursors in trisodium phosphate (Na3PO4) aqueous solution. The morphology, phase, chemical compositions, lattice constants and the degradability of the products were characterized. The Si/Sr-HAp nanowires with diameter of about 60 nm and up to 2 μm in length were obtained after hydrothermal treatment of the Sr-CS precursors. The Sr and Si substitution amount of the HAp nanowires could be well regulated by facile tailoring the Sr substitution level of the precursors and the reaction ratio of the precursor/solution, respectively. The SiO4 tetrahedra and Sr2+ ions occupied the crystal sites of the HAp, and the lattice constants increased apparently with the increase of the substitution amount. EDS mapping also suggested the uniform distribution of Si and Sr in the synthetic nanowires. Moreover, the Si/Sr-substitution apparently improved the degradability of the HAp materials. Our study suggested that the precursor transformation method provided a facile approach to synthesize the Si/Sr co-substituted HAp nanowires with controllable substitution amount, and the synthetic Si/Sr-HAp nanowires might be used as bioactive materials for hard tissue regeneration applications. - Highlights: • Si/Sr-HAp nanowires were hydrothermally transformed from Srx-CaSiO3 precursors. • The Si/Sr-substitution level could be facilely regulated. • The nanowire-like morphology and composition could be simultaneously regulated

  19. Preparation and luminescence characteristics of Eu-doped calcium chloride silicate Ca7Si2O8Cl6

    International Nuclear Information System (INIS)

    Highlights: • Ca7Si2O8Cl6: Eu prepared in a reducing atmosphere contains Eu2+ and Eu3+ centers. • With increasing Eu-doping Eu2+ emission decrease and Eu3+ f–f transitions increase. • Luminescence color can be tunable Upon an excitation with near UV-light. • QE of Ca7Si2O8Cl6: 0.04Eu is 47.5% under excitation of 390 nm. -- Abstract: Eu-activated (0.1–5.0 mol%) calcium chloride silicate Ca7Si2O8Cl6 phosphors were prepared by means of ceramic method, which were characterized by X-ray powder diffraction and SEM measurements. The luminescence properties were investigated by the photoluminescence excitation and emission spectra, the luminescence decay lifetimes, the color coordinates and the internal quantum efficiency. Ca7Si2O8Cl6:Eu contains two kinds of Eu-emission centers, i.e., Eu2+ and Eu3+ ions, even it was prepared in a reducing atmosphere. Eu2+ and Eu3+ ions which present the characteristic broad band (5d → 4f) and narrow 4f → 4f luminescent features, respectively. The luminescence mechanism was discussed by analyzing the spectra, concentration-dependent emission intensity and lifetimes. With increasing Eu-doping, the energy transfer happens from Eu2+ to Eu3+ centers. Upon an excitation with near UV light, the luminescence color can be tunable from green to orange with increasing the Eu-doping because of the changes of the luminescence components from Eu3+ and Eu2+ ions in Ca7Si2O8Cl6 host. This is a potential phosphor combining both luminescence effects of Eu2+ and Eu3+ ions

  20. Functionalized calcium silicate nanofibers with hierarchical structure derived from oyster shells and their application in heavy metal ions removal.

    Science.gov (United States)

    You, Weijie; Hong, Mingzhu; Zhang, HaiFeng; Wu, Qiuping; Zhuang, Zanyong; Yu, Yan

    2016-06-21

    Inorganic hierarchical nanostructures have remarkable potential applications in environmental metal remediation; however, their applications usually suffer from low capacity, high cost, and difficulties in the recycling of adsorbents. We previously reported a facile strategy to synthesize acid-insoluble calcium silicate hydrates (CSH) from oyster shells, a representative kind of biowaste. However, little is known of the structure, size, and morphology of the as-prepared CSH, which hampers the improvement of their adsorption capacities. In this work, systematic investigation of the structures of as-generated CSH demonstrate that they have a hierarchically porous structure composed of thin nano-sheets, where each nano-sheet is assembled by nano-fibers with width of around ten nanometers. The hierarchical nanostructures with pore size of ∼12 nm provide a significant amount of active sites to graft polyethyleneimine (PEI), which enables the efficient extraction of both Cu(ii) cations and Cr(vi) anions from the aqueous solution. Batch experiments further indicate that the PEI-modified PCSH exhibit a maximum adsorption capacity of 203 and 256 mg g(-1) for Cu(ii) and Cr(vi), respectively, much higher than that of CSH, OS and many other adsorbents in literature. The adsorption of Cu(ii) and Cr(vi) proved to be spontaneous and exothermic. Combining the pH-dependent experiments with X-ray photoelectron spectroscopy analysis, the underlying mechanism is discussed. PCSH derived from OS biowaste maintains an efficient extraction ability toward Cu(ii) and Cr(vi) after five adsorption-desorption cycles. It is also applicable for treating various kinds of heavy metal ions and organic pollutants, showing potentially wide applications in water treatment. PMID:27221228

  1. Preparation and Evaluation of Solid Dispersion Tablets by a Simple and Manufacturable Wet Granulation Method Using Porous Calcium Silicate.

    Science.gov (United States)

    Fujimoto, Yumi; Hirai, Nobuaki; Takatani-Nakase, Tomoka; Takahashi, Koichi

    2016-01-01

    The aim of this study was to prepare and evaluate solid dispersion tablets containing a poorly water-soluble drug using porous calcium silicate (PCS) by a wet granulation method. Nifedipine (NIF) was used as the model poorly water-soluble drug. Solid dispersion tablets were prepared with the wet granulation method using ethanol and water by a high-speed mixer granulator. The binder and disintegrant were selected from 7 and 4 candidates, respectively. The dissolution test was conducted using the JP 16 paddle method. The oral absorption of NIF was studied in fasted rats. Xylitol and crospovidone were selected as the binder and disintegrant, respectively. The dissolution rates of NIF from solid dispersion formulations were markedly enhanced compared with NIF powder and physical mixtures. Powder X-ray diffraction (PXRD) confirmed the reduced crystallinity of NIF in the solid dispersion formulations. Fourier transform infrared (FT-IR) showed the physical interaction between NIF and PCS in the solid dispersion formulations. NIF is present in an amorphous state in granules prepared by the wet granulation method using water. The area under the plasma concentration-time curve (AUC) and peak concentration (Cmax) values of NIF after dosing rats with the solid dispersion granules were significantly greater than those after dosing with NIF powder. The solid dispersion formulations of NIF prepared with PCS using the wet granulation method exhibited accelerated dissolution rates and superior oral bioavailability. This method is very simple, and may be applicable to the development of other poorly water-soluble drugs. PMID:27039831

  2. Different response of osteoblastic cells to Mg(2+), Zn(2+) and Sr(2+) doped calcium silicate coatings.

    Science.gov (United States)

    Hu, Dandan; Li, Kai; Xie, Youtao; Pan, Houhua; Zhao, Jun; Huang, Liping; Zheng, Xuebin

    2016-03-01

    Mg(2+), Zn(2+) and Sr(2+) substitution for Ca(2+) in plasma sprayed calcium silicate (Ca-Si) coatings have been reported to impede their degradation in physiological environment and, more importantly, to improve their biological performance. The reason for the improved biological performance is still elusive and, especially, the contribution of the dopant ions is lack of obvious and direct evidence. In this study, we aim to identify the effect of Mg(2+), Zn(2+) and Sr(2+) incorporation on the osteogenic ability of Ca-Si based coatings (Ca2MgSi2O7, Ca2ZnSi2O7 and Sr-CaSiO3) by minimizing the influence of Ca and Si ions release and surface physical properties. Similar surface morphology, crystallinity and roughness were achieved for all samples by optimizing the spray parameters. As expected, Ca and Si ions release from all the coatings showed the comparable concentration with immersing time. The response of MC3T3-E1 cells onto Mg(2+), Zn(2+) and Sr(2+) doped Ca-Si coatings were studied in terms of osteoblastic adhesion, proliferation, differentiation and mineralization. The results showed that the level of cell adhesion and proliferation increased the most on the surface of Mg-modified coating. Gene expressions of early markers of osteoblast differentiation (COL-I and ALP mRNA) were obviously improved on Zn-modified coating. Gene expressions of later markers for osteoblast differentiation (OPN and OC mRNA) and mineralized nodules formation were obviously accelerated on the surface of Sr-modified coating. Since Mg(2+), Zn(2+) and Sr(2+) play a regulatory role in different stages of osteogenesis, it may be possible to utilize this in the development of new coating materials for orthopedic application. PMID:26787488

  3. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate

    OpenAIRE

    Ivanov, Vadim; Ivanova, Svetlana; KALINOVSKY, TATIANA; NIEDZWIECKI, ALEKSANDRA; RATH, MATTHIAS

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition...

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

    CERN Document Server

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

    2013-01-01

    We use Brownian dynamics simulations to study the permeation properties of a generic electrostatic model of a biological ion channel as a function of the fixed charge Q_f at its selectivity filter. We reconcile the recently-discovered discrete calcium conduction bands M0 (Q_f=1e), M1 (3e), M2 (5e) with the set of sodium conduction bands L0 (0.5-0.7e), L1 (1.5-2e) thereby obtaining a completed pattern of conduction and selectivity bands v Q_f for the sodium-calcium channels family. An increase of Q_f leads to an increase of calcium selectivity: L0 (sodium selective, non-blocking channel) -> M0 (non-selective 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 L1 band is identified with the eukaryotic (DEKA) sodium channel, and L0 (speculatively) with the bacterial NaChBac channel. The scheme created is able to account for the experimentally observed mutation-induced ...

  5. 水化硅酸钙的制备及磷回收性能表征%Preparation and phosphorus recovery performance of calcium silicate hydrate

    Institute of Scientific and Technical Information of China (English)

    关伟; 吉芳英; 陈晴空; 晏鹏; 张千

    2012-01-01

    Calcium silicate hydrate with phosphorus recovery efficiency was synthesized by carbide residue and silica. Effect of prepared method on phosphorus recovery efficiency of calcium silicate hydrate was studied. Mechanism of phosphorus recovery was revealed by XRD. Microstructure of calcium silicate hydrate was characterized by BET and SEM. Capacity of Ca^2+ and OH release was investigated. The considerable preparation conditions are obtained on the condition of Ca/Si molar ratio 1.6 - 1, reaction temperature 170℃, reaction time 4.5h, stirring intensity 90r/min. Phosphorus content of product of phosphorus recovery reached 18.64. The prepared calcium silicate hydrate has a high BET surface area 113. 3572m^2/g with porous structure. Concentration of Ca^2+ release reached 3.52mg/g. This material could recover phosphorus from wastewater in the form of hydroxyl calcium phosphate on the condition of pH=9.%以电石渣和白碳黑分别作为钙质和硅质原料,采用水热法制备具有磷回收特性的水化硅酸钙。研究了制备条件对水化硅酸钙磷回收性能的影响,采用XRD揭示了水化硅酸钙的磷回收机制。通过BET、SEM表征了水化硅酸钙的微观结构,考察了水化硅酸钙的溶钙供碱能力。钙硅摩尔比为1.6∶1,水热反应温度为170℃,水热反应时间为4.5h,搅拌强度为90r/min的条件下所制备的水化硅酸钙,其磷回收产品中的磷含量达到18.64%。该材料具有多孔结构,比表面积达到113.3572m2/g,能够溶出的Ca2+浓度为3.52mg/g,这些溶钙供碱特性使得该材料能够在pH值=9.0的环境下以羟基磷酸钙的形式从污水中回收磷。

  6. Synthesis and characterization of a novel layered sodium titanium silicate Na2TiSi2O7·2H2O

    International Nuclear Information System (INIS)

    A novel layered sodium titanium silicate Na2TiSi2O7·2H2O has been synthesized by the reaction of a titanium-hydrogen peroxide complex and silicic acid in alkaline media under mild hydrothermal conditions (200 degree C). The product was characterized by elemental analysis, TGA, FT-IR, MAS 29Si and 23Na NMR and X-ray spectroscopy. The intercalation reaction of n-alkylamines from the gaseous phase and the ion exchange behavior of Na2TiSi2O7·2H2O towards alkali, alkaline earth and some transition metal ions in model individual and complex solutions were studied. It was found that the layered sodium titanium silicate contains acidic hydroxyl functional groups, which results in cation uptake at pH>1.5. The high affinity of the exchanger for cesium in weakly acid and neutral solutions makes it a promising material for the treatment of some types of nuclear wastes, contaminated ground water and different biological liquors. 20 refs., 10 figs., 6 tabs

  7. The effect of sodium silicate concentration on microstructure and corrosion properties of MAO-coated magnesium alloy AZ31 in simulated body fluid

    Directory of Open Access Journals (Sweden)

    B. Salami

    2014-03-01

    Full Text Available In recent years, magnesium and its alloys are considered as biodegradable implants. However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed. In this investigation, micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid. Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current. The effects of silicate concentration and conductivity of electrolyte solution on microstructure and corrosion properties of coating were evaluated. Scanning electron microscopy showed that a thick and condensed coating is formed after enough anodizing period. Energy dispersive spectroscopy showed that Si, O and Mg are the main components of the coating. Corrosion resistance of the coated and uncoated samples was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy tests in SBF at 37 °C and pH of 7.4. Maximum corrosion resistance was achieved at 30 g/L concentration of sodium silicate in anodizing solution. It was observed that further increase in silicate concentration decreased the corrosion resistance.

  8. Haemorrhagic effects of sodium heparin and calcium heparin prophylaxis in patients undergoing mastectomy.

    Science.gov (United States)

    Lee, R E; Ho, K N; Karran, S J; Taylor, I

    1989-06-01

    In a double-blind prospective clinical trial 75 consecutive patients undergoing mastectomy were randomly allocated to one of three groups. Twenty-five patients received perioperative anti-thromboembolic therapy with sodium heparin and 25 with calcium heparin. The remaining 25 patients were given anti-embolism stockings but no heparin. The total postoperative blood loss and period of drainage did not differ between the two groups given heparin, but a total of 10 of these 50 patients suffered haemorrhagic complications in the form of severe bruising or haematoma postoperatively. Of the patients given no heparin, none suffered haemorrhagic complications and the blood loss following the first 24-hour postoperative period was significantly less than in the groups given heparin. PMID:2681717

  9. SMALL-SCALE PILOT EVALUATION OF CALCIUM- AND SODIUM-BASED SORBENTS FOR DRY SO2 REMOVAL

    Science.gov (United States)

    The paper discusses a 100 cu m/h pilot facility (consisting of a spray dryer, a sorbent injection system, a duct section, and a pulse-jet baghouse or cyclone separator) used for testing the reaction at low temperature between various calcium- and sodium-based sorbents and SO2 in ...

  10. Statement on the exposure assessment of sodium stearoyl-2-lactylate and calcium stearoyl-2-lactylate including exposure resulting from extension of the authorisation of sodium stearoyl-2-lactylates

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to food (ANS)

    2013-01-01

    Following a request by the European Commission, the Scientific Panel on Food Additives and Nutrient Sources added to Food (ANS) carried out an exposure assessment of sodium stearoyl-2-lactylate (E 481) and calcium stearoyl-2-lactylate (E 482) as a food additive, including an extension of the uses to use the additives in emulsified cooked meat products (e.g. mortadella, paté). Reflecting the data on actual use levels provided by food industry, the combined exposure to sodium stearoyl-2-lactyla...

  11. Influence of sodium, calcium, magnesium, and ammonium in the sorption of cadmium in a zeolite rock

    International Nuclear Information System (INIS)

    The cadmium is one of the more toxic heavy metals and the water pollution by this metal, is originated by industries whose turn is the production of batteries, electroplating processes, the production of pigments and in the refinement process of others metals. The objective of this work was to evaluate the ion exchange of cadmium using natural zeolite, obtained from the Arroyo zone, La Haciendita Municipality, in the State of Chihuahua. The parameters considered in this investigation were: the sorption time, the pH, the initial concentration of cadmium and the influence of sodium, calcium, magnesium and ammonium on the sorption of cadmium in the natural zeolite. Also, the theoretical pattern for kinetics and isotherm that better it is adjusted to those experimental results it was determined. The experimentation results allowed to establish the following conclusions: the sorption of the cadmium doesn't depend on the pH in an interval between 4 and 6; the pattern that better it describes the kinetics it is that of Pseudo-second order of Ho and Mc Kay; the Langmuir-Freundlich pattern is the one that better it describes the sorption isotherm and the calcium is the component that interferes in an important manner in the sorption of cadmium. The carried out investigation contributes to the definition of some of the parameters that should be considered in the development of ion exchangers for the cadmium removal. (Author)

  12. Clinical and radiographic assessment of the efficacy of calcium silicate indirect pulp capping: a randomized controlled clinical trial.

    Science.gov (United States)

    Hashem, D; Mannocci, F; Patel, S; Manoharan, A; Brown, J E; Watson, T F; Banerjee, A

    2015-04-01

    The aims of this study were to assess the effectiveness of calcium silicate cement (Biodentine) versus glass ionomer cement (GIC; control group) as indirect pulp capping materials in patients with reversible pulpitis and to compare the effectiveness of cone beam computed tomography (CBCT) versus periapical (PA) radiographs in detecting PA changes at baseline (T0) and at 12 mo (T12) postoperatively. Seventy-two restorations (36 Biodentine, 36 Fuji IX) were placed randomly in 53 patients. CBCT/PA radiographs were taken at T0 and T12. Two calibrated examiners assessed the presence/absence and increase/decrease in the size of existing PA radiolucencies under standardized conditions. The Kappa coefficient evaluated statistically the effectiveness of CBCT versus PA radiographs in detecting PA changes. Chi-square/Mann-Whitney tests were used to evaluate the association between PA changes in CBCT with various clinical measures. Significance was predetermined at α = 0.05. Clinical success rates for Biodentine and Fuji IX GIC were 83.3%. CBCT was significantly more effective in detecting PA radiolucencies compared with radiographs (P = 0.0069). Of the teeth, 65.4% and 90.4% were deemed healthy using CBCT and PA radiographs, respectively, at T12. Healing/healed rates were 17.3%/0%, while new/progressed radiolucency were 30.8%/9.6% with CBCT/PA radiographs, respectively. Seventy-one percent of healed lesions had received Biodentine; 88% of new/progressed lesions received Fuji IX GIC. Teeth presenting with an initial CBCT PA lesion had a failure rate of 63%, whereas teeth with no initial lesion had a failure rate of 16%. Although no statistically significant difference was detected in the clinical efficacy of Biodentine/Fuji IX when used as indirect pulp capping materials in patients with reversible pulpitis, CBCT showed a significant difference in that most healed CBCT lesions had received Biodentine while most that did not heal received Fuji IX. Longer-term follow-up is

  13. Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements

    Science.gov (United States)

    GUERREIRO-TANOMARU, Juliane Maria; VÁZQUEZ-GARCÍA, Fernando Antonio; BOSSO-MARTELO, Roberta; BERNARDI, Maria Inês Basso; FARIA, Gisele; TANOMARU, Mario

    2016-01-01

    ABSTRACT Objective Mineral Trioxide Aggregate (MTA) is a calcium silicate cement composed of Portland cement (PC) and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2) and hydroxyapatite nanoparticles (HAn). Material and Methods White MTA (Angelus, Brazil); PC (70%)+ZrO2 (30%); PC (60%)+ZrO2 (30%)+HAn (10%); PC (50%)+ZrO2 (30%)+HAn (20%) were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1) in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. Results There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p>0.05) and these cements presented higher pH levels than MTA (p<0.05). The highest solubility was observed in PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p<0.05). MTA had the shortest initial setting time (p<0.05). All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05). Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05) after the post-manipulation period of 2 days. Conclusions The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%), the final setting time

  14. Calmodulin and calcium differentially regulate the neuronal Nav1.1 voltage-dependent sodium channel

    International Nuclear Information System (INIS)

    Highlights: → Both Ca++-Calmodulin (CaM) and Ca++-free CaM bind to the C-terminal region of Nav1.1. → Ca++ and CaM have both opposite and convergent effects on INav1.1. → Ca++-CaM modulates INav1.1 amplitude. → CaM hyperpolarizes the voltage-dependence of activation, and increases the inactivation rate. → Ca++ alone antagonizes CaM for both effects, and depolarizes the voltage-dependence of inactivation. -- Abstract: Mutations in the neuronal Nav1.1 voltage-gated sodium channel are responsible for mild to severe epileptic syndromes. The ubiquitous calcium sensor calmodulin (CaM) bound to rat brain Nav1.1 and to the human Nav1.1 channel expressed by a stably transfected HEK-293 cell line. The C-terminal region of the channel, as a fusion protein or in the yeast two-hybrid system, interacted with CaM via a consensus C-terminal motif, the IQ domain. Patch clamp experiments on HEK1.1 cells showed that CaM overexpression increased peak current in a calcium-dependent way. CaM had no effect on the voltage-dependence of fast inactivation, and accelerated the inactivation kinetics. Elevating Ca++ depolarized the voltage-dependence of fast inactivation and slowed down the fast inactivation kinetics, and for high concentrations this effect competed with the acceleration induced by CaM alone. Similarly, the depolarizing action of calcium antagonized the hyperpolarizing shift of the voltage-dependence of activation due to CaM overexpression. Fluorescence spectroscopy measurements suggested that Ca++ could bind the Nav1.1 C-terminal region with micromolar affinity.

  15. Calmodulin and calcium differentially regulate the neuronal Nav1.1 voltage-dependent sodium channel

    Energy Technology Data Exchange (ETDEWEB)

    Gaudioso, Christelle; Carlier, Edmond; Youssouf, Fahamoe [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Clare, Jeffrey J. [Eaton Pharma Consulting, Eaton Socon, Cambridgeshire PE19 8EF (United Kingdom); Debanne, Dominique [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France); Alcaraz, Gisele, E-mail: gisele.alcaraz@univmed.fr [INSERM U641, Institut Jean Roche, Marseille F-13344 (France); Universite de la Mediterranee, Faculte de Medecine Secteur Nord, IFR 11, Marseille F-13344 (France)

    2011-07-29

    Highlights: {yields} Both Ca{sup ++}-Calmodulin (CaM) and Ca{sup ++}-free CaM bind to the C-terminal region of Nav1.1. {yields} Ca{sup ++} and CaM have both opposite and convergent effects on I{sub Nav1.1}. {yields} Ca{sup ++}-CaM modulates I{sub Nav1.1} amplitude. {yields} CaM hyperpolarizes the voltage-dependence of activation, and increases the inactivation rate. {yields} Ca{sup ++} alone antagonizes CaM for both effects, and depolarizes the voltage-dependence of inactivation. -- Abstract: Mutations in the neuronal Nav1.1 voltage-gated sodium channel are responsible for mild to severe epileptic syndromes. The ubiquitous calcium sensor calmodulin (CaM) bound to rat brain Nav1.1 and to the human Nav1.1 channel expressed by a stably transfected HEK-293 cell line. The C-terminal region of the channel, as a fusion protein or in the yeast two-hybrid system, interacted with CaM via a consensus C-terminal motif, the IQ domain. Patch clamp experiments on HEK1.1 cells showed that CaM overexpression increased peak current in a calcium-dependent way. CaM had no effect on the voltage-dependence of fast inactivation, and accelerated the inactivation kinetics. Elevating Ca{sup ++} depolarized the voltage-dependence of fast inactivation and slowed down the fast inactivation kinetics, and for high concentrations this effect competed with the acceleration induced by CaM alone. Similarly, the depolarizing action of calcium antagonized the hyperpolarizing shift of the voltage-dependence of activation due to CaM overexpression. Fluorescence spectroscopy measurements suggested that Ca{sup ++} could bind the Nav1.1 C-terminal region with micromolar affinity.

  16. EFFECTS OF SODIUM AND CALCIUM IN LIGNITE ON THE PERFORMANCE OF ACTIVATED CARBON PRODUCTS; TOPICAL

    International Nuclear Information System (INIS)

    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 and 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-12-01

    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

  18. Sodium fluoride and casein phosphopeptide-amorphous calcium phosphate cream plus sodium fluoride efficacy in preventing enamel erosion in a simulated oral environment study model

    OpenAIRE

    Cristiane Mariote Amaral; Maria Elisa da Silva NG Miranda; Danielly S Correa; Eduardo M. Silva

    2014-01-01

    Aim: The aim of this study was to evaluate the effectiveness of dentifrices containing high concentrations of sodium fluoride (NaF) and casein phosphopeptide-amorphous calcium phosphate cream plus fluoride (CPP-ACPF) in prevention of the erosion in a simulated oral environment study model. Subjects and Methods: Fifteen flat human enamel specimens were polished and half of the surfaces were protected with adhesive tape. Initial Knoop microhardness (KHN) and surface roughness (SR) were meas...

  19. Bones and Crohn's: No benefit of adding sodium fluoride oribandronate to calcium and vitamin D

    Institute of Scientific and Technical Information of China (English)

    Jochen Klaus; Max Reinshagen; Katharina Herdt; Christoph Schr(o)ter; Guido Adler; Georg BT von Boyen; Christian von Tirpitz

    2011-01-01

    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 Crohn's 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 femurand 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 thesecond 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, duringthe 1.0, 2.25 and 3.5 year periods (PP analysis), no treatment regimen was superior in any in- or betweengroup analyses. In the ITT analysis, similar results in allin- and between-group analyses with a significant ingroup 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

  20. A short introduction to the new principle of binding ration calcium with sodium zeolite

    DEFF Research Database (Denmark)

    Jørgensen, R J; Bjerrum, M J; Classen, H;

    2003-01-01

    This paper summarise the development of the new principle of preventing parturient hypocalcaemia by reducing the bioavailability of ration calcium with calcium binders, based on the idea that a negative calcium balance would stimulate natural defence mechanisms against threatening hypocalcaemia. ...

  1. Scientific Opinion on the safety and efficacy of vitamin C (ascorbic acid, sodium ascorbate, calcium ascorbate, ascorbyl palmitate, sodium calcium ascorbyl phosphate and sodium ascorbyl phosphate as a feed additive for all animal species based on a dossier submitted by DSM Nutritional Products Ltd

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-02-01

    Full Text Available Vitamin C is essential for primates, guinea pigs and fish. Vitamin C, in the form of ascorbic acid and its calcium and sodium salts, ascorbyl palmitate, sodium calcium ascorbyl phosphate and sodium ascorbyl phosphate, is safe for all animal species. Setting a maximum content in feed and water for drinking is not considered necessary. Data on the vitamin C consumption of consumers are based on the levels of vitamin C in foodstuffs, including food of animal origin, produced in accordance with current EU legislation on the supplementation of feed with vitamin C. The exposure is far below the guidance level. Any potential contribution of the use of vitamin C in feed is therefore already considered in the above data. Consequently, the use of vitamin C in animal nutrition is not of concern for consumer safety. In the absence of inhalation toxicity studies it would be prudent to assume that inhalation of dust from the additives presents a health hazard to workers. Sodium calcium ascorbyl phosphate is not an irritant to skin and eyes and is unlikely to be a skin sensitiser. This conclusion is extrapolated to sodium ascorbyl phosphate. In the absence of data, ascorbic acid, sodium ascorbate, calcium ascorbate and ascorbyl palmitate should be considered as irritant to skin and eyes and as dermal sensitisers. The supplementation of feed with vitamin C does not pose a risk to the environment. Ascorbic acid, sodium calcium ascorbyl phosphate and sodium ascorbyl phosphate are regarded as effective sources of vitamin C when added to feed or water for drinking. Since ascorbic acid, sodium ascorbate, calcium ascorbate and ascorbyl palmitate are authorised for use as antioxidants in food and their function in feed is essentially the same as that in food, no further demonstration of efficacy is considered necessary.

  2. Recovery of phosphorus from wastewater by calcium silicate hydrate%水化硅酸钙回收污水中磷的试验研究

    Institute of Scientific and Technical Information of China (English)

    王鑫永; 陈雪初; 何圣兵; 李春杰; 孔海南; 李思劫

    2011-01-01

    Taking simulation wastewater as the research object, a test on phosphorus removal from waste-water by synthesized calcium silicate hydrate was carried out, and the influences of contact time, Ca2+ concentration, initial pH value, interfering ion and some other factors on phosphorus removal were investigated. The results of the test on phosphorus recovery from actual wastewater by calcium silicate hydrate showed that, after 8 hours of reaction, the amount of phosphorus recovery reached 101 mg/g; the phosphorus content of the wastewater, converted into P2O5, was larger then that of the common water-soluble phosphate fertilizer: calcium superphosphate; furthermore, phosphorus was released rapidly after the product had been treated by acid, and the release rate was nearly 100% within 1 hour, which indicated that, the said material could enrich and reclaim phosphorus from actual wastewater, and would have good application prospect.%采用合成水化硅酸钙进行污水除磷试验,以模拟污水为研究对象,考察了接触时间、Ca2+浓度、初始pH值、干扰离子等因素对除磷效果的影响,在利用水化硅酸钙回收实际污水中磷的试验发现,在处理8h后除磷量达到101 mg/g,折合P2O5含量超过常用的水溶性磷肥过磷酸钙,且产物经酸处理后将快速释磷,在1h后磷释放率接近100%,显示该材料能富集回收实际污水中的磷,具有较好的应用前景.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schumaker, Karen S [Professor

    2013-10-24

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

  4. Synthesis, characterization, and in vitro release of diclofenac sodium from hybrid nanostructured magnetite-calcium pectinate

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Raj Kumar, E-mail: duttafcy@iitr.ernet.in; Sahu, Saurabh, E-mail: saurabhsahu12@gmail.com [Indian Institute of Technology Roorkee, Analytical Chemistry Laboratory, Department of Chemistry (India); Reddy, V. R., E-mail: vrreddy@csr.res.in [UGC-DAE Consortium for Scientific Research (India)

    2012-08-15

    A stable spherical nanostructured calcium pectinate loaded with diclofenac sodium (DS) and functionalized by superparamagnetic iron oxide nanoparticles, referred as MCPDS, was developed as a potential magnetically targeted drug delivery system. The sizes of the MCPDS were in the range of 100-200 nm in dried condition, confirmed by scanning electron microscopy and transmission electron microscopy. In the aqueous medium, the sizes of MCPDS were in the range 300 {+-} 50 nm, measured by dynamic light scattering technique. The X-ray diffraction and {sup 57}Fe Moessbauer spectroscopy confirmed magnetite phase in MCPDS. The magnetic property of the MCPDS nanostructures was confirmed from high saturation magnetization (44.05 emu/g), measured using a vibrating sample magnetometer. The superparamagnetic property of MCPDS was characterized by superconducting quantum unit interference device magnetometry and corroborated by Moessbauer spectroscopy. The loading efficiency of DS in MCPDS was measured by UV-Vis spectrophotometry and corroborated by thermal analysis. The in vitro release of the drug from MCPDS in simulated gastrointestinal fluids and in phosphate buffer solution was found to be pH sensitive and exhibited sustained release property. The cumulative drug release agreed well with that of swelling controlled diffusion mechanism, given by the Korsemeyer Peppas model.

  5. Experimental studies on the anticoagulant and antithrombotic effects of sodium and calcium pentosan polysulphate.

    Science.gov (United States)

    Giedrojć, J; Radziwon, P; Klimiuk, M; Bielawiec, M; Breddin, H K; Kłoczko, J

    1999-03-01

    In the present study we have compared the antithrombotic and anticoagulant properties of sodium and calcium derivatives of pentosan polysulphate (Na-PPS, Ca-PPS). The antithrombotic effect of these agents have been investigated in an experimental thrombosis model in which rat mesenteric venules diameter of 20-30 microm were injured by well defined Argon laser lesions. Furthermore, the in vivo and in vitro anticoagulant activities (aPTT, Heptest) of these agents have been studied. Thrombus formation was significantly inhibited after s.c. injection of Na-PPS and Ca-PPS in doses above 10 mg/kg. The duration of the antithrombotic effect lasted 8 h for Na-PPS and 12 h for Ca-PPS. After oral administration of Na-PPS an antithrombotic effect was not observed. Oral application of Ca-PPS in doses higher than 20 mg/kg significantly inhibited thrombus formation. Na-PPS and Ca-PPS markedly prolonged clotting time in aPTT and Heptest in concentrations ranging from 0.01 to 0.2 mg/ml rat PTT. Two h after s.c. administration of these agents in a dose 10 mg/kg, the aPTT increased 3-fold and Heptest 2.5-fold compared to controls. After oral application of 50 mg/kg Na-PPS and Ca-PPS no effect on coagulation test could be measured. PMID:10210159

  6. Large-scale expression of recombinant cardiac sodium-calcium exchange in insect larvae.

    Science.gov (United States)

    Hale, C C; Zimmerschied, J A; Bliler, S; Price, E M

    1999-02-01

    Recombinant bovine cardiac sodium-calcium exchange (NCX1) in a baculovirus construct was used to infect cabbage looper larvae (Trichoplusia ni). Infected larvae were homogenized and larvae membrane vesicles were purified. Western blot analysis indicated the presence of recombinant NCX1 protein in vesicles from infected larvae but not in controls. Vesicles from infected larvae expressed high levels of NCX1 activity (1.7 nmol Ca2+/mg protein/s) while vesicles from control larvae had no activity. NCX1 in larvae vesicles was bidirectional. Kinetic analysis yielded a Vmax of 3.6 nmol Ca2+/mg protein/s and a Km for Ca of 4.2 microM. NCX1 activity was inhibited by the exchange inhibitory peptide with an IC50 of 4 microM. These data demonstrate a novel and efficient method for the expression of large amounts of active recombinant NCX1 protein that has general application for expression and analysis of recombinant membrane proteins. PMID:10024479

  7. Molecular Modeling of Ammonium, Calcium, Sulfur, and Sodium Lignosulphonates in Acid and Basic Aqueous Environments

    Science.gov (United States)

    Salazar Valencia, P. J.; Bolívar Marinez, L. E.; Pérez Merchancano, S. T.

    2015-12-01

    Lignosulphonates (LS), also known as lignin sulfonates or sulfite lignin, are lignins in sulfonated forms, obtained from the "sulfite liquors," a residue of the wood pulp extraction process. Their main utility lies in its wide range of properties, they can be used as additives, dispersants, binders, fluxing, binder agents, etc. in fields ranging from food to fertilizer manufacture and even as agents in the preparation of ion exchange membranes. Since they can be manufactured relatively easy and quickly, and that its molecular size can be manipulated to obtain fragments of very low molecular weight, they are used as transport agents in the food industry, cosmetics, pharmaceutical and drug development, and as molecular elements for the treatment of health problems. In this paper, we study the electronic structural and optical characteristics of LS incorporating ammonium, sulfur, calcium, and sodium ions in acidic and basic aqueous media in order to gain a better understanding of their behavior and the very interesting properties exhibit. The studies were performed using the molecular modeling program HyperChem 5 using the semiempirical method PM3 of the NDO Family (neglect of differential overlap), to calculate the structural properties. We calculated the electronic and optical properties using the semiempirical method ZINDO / CI.

  8. Preparation of calcium fluoroaluminosilicate glasses containing sodium and phosphorus by the nonhydrolytic sol-gel method

    International Nuclear Information System (INIS)

    Aluminum and silicon oxide-based inorganic matrices have been extensively studied because of their countless applications. Dental cements consist of aluminum and silicon-based amorphous polymeric materials containing fluoride, sodium, phosphorus and calcium, which are also good candidates for bone replacement. The nonhydrolytic sol-gel method has emerged as an alternative route for the preparation of these materials under milder conditions than those employed in traditional methods, such as oxide fusion. The main advantages of the nonhydrolytic sol-gel method include the use of low temperatures and the ready availability and easy purification of the precursors. Together, these factors have contributed to the production of highly pure materials with controlled porosity and nanometric particles. Dental restorations based on aluminosilicate matrices are known as glass ionomer cements. These materials have interesting physical and dental properties, mainly because they display anticariogenic activity and exhibit prolonged adhesiveness to the dental structure. The base of the ionomer is an aluminosilicate that is industrially synthesized by the fusion of SiO2, Al2O3, AlF3, CaF2, NaF and AlPO4, in various concentrations. The characterizations conducted in this study reveal that this ionomer displays interesting properties, so its use as a precursor of dental cement and a biomaterial for bone replacement is highly recommended

  9. Levels of ammonium, sulfate, chloride, calcium, and sodium in snow and ice from southern Greenland

    International Nuclear Information System (INIS)

    Chemical analysis of surface snows and dated ice core samples from Dye 3, Greenland, suggests that the ammonium cation is a major constituent in all samples and that the annual ammonium levels present in the south Greenland samples have varied from 3.3 to 26.3 μg/kg between the seventeenth century and the present time. The annual range of 1974--1975 surface samples was between 3.8 and 8.8 μg/kg, while the mean was 5.7 +- 1.8 μ/kg. The recent large-scale uses of fixed nitrogen fertilizers and industrial pollution have apparently not affected the levels of ammonia reaching southern Greenland. The sodium and chloride present are predominantly derived from ocean spray, while more than 90% of the calcium is of continental origin. The levels of these three elements have not apparently been affected by human activity since the industrial revolution. Sulfate levels have increased dramatically since the industrial revolution, suggesting that sulfate of anthropogenic origin is the most important source of sulfate in modern snows from southern Greenland. The amount of the sulfuric acid neutralized by the ammonium cations was approximately 100% in the seventeenth and eighteenth centuries, dropping to approximately 20% in the 1974--1975 samples. These figures imply that there has been in increase in the acidity of precipitation in southern Greenland since the end of the eighteenth ce

  10. Determination of calcium, copper, chromium, iron, magnesium, manganese, potassium, sodium and zinc in ethanol by atomic absorption spectrometry

    International Nuclear Information System (INIS)

    The direct determinacao of calcium, copper, chomium, iron, magnesium, manganese, potassium, sodium and zinc in ethanol by atomic absorption spectrometry with, air-acetylene flame is proposed. Effects of fuel/oxidant ratio, burner height and water content in the samples were investigated in detail. The method allows the determition of the elements with good precision (r.s.d. -1 for the elements tested. (author)

  11. Determination of sodium, potassium, calcium, magnesium, iron, copper, zinc and mercury in contaminated wheat and wheat flour

    International Nuclear Information System (INIS)

    The wheat and wheat flour samples from district Khairpur, were dissolved in acids and analyzed spectrophotometrically for mercury contents, using dithiozone method. Mercury was found in 0.92-5.8 mg/ kg range, above the safe limits for human consumption, samples were also analysed for sodium, potassium, calcium, magnesium, iron, copper and zinc, after dry ashing, followed by acid dissolution and flame atomic absorption determination. Metal ions were found within the normal limits reported for wheat and wheat flour. (author)

  12. Effects of two fast-setting calcium-silicate cements on cell viability and angiogenic factor release in human pulp-derived cells.

    Science.gov (United States)

    Chung, Chooryung J; Kim, Euiseong; Song, Minju; Park, Jeong-Won; Shin, Su-Jung

    2016-05-01

    Mineral trioxide aggregate (MTA) is considered a pulp-capping agent of choice, but has the drawback of a long setting time. This study aimed to assess two different types of calcium-silicate cements as pulp-capping agents, by investigating their in vitro cytotoxicity and angiogenic effects in human pulp cells. ProRoot MTA, Endocem Zr, and Retro MTA were prepared as set or freshly mixed pellets. Human pulp-derived cells were grown in direct contact with these three cements, Dycal, or no cement, for 7 days. Initial cell attachment, viability, calcium release, and the levels of vascular endothelial growth factor (VEGF), angiogenin, and basic fibroblast growth factor (FGF-2) were evaluated statistically using a linear mixed model (P calcium concentration compared with the control group (P  0.05). We demonstrate that Retro MTA, which has a short setting time, has similar biocompatibility and angiogenic effects on human pulp cells, and can therefore potentially be as effective in pulp capping as ProRoot MTA. Endocem Zr showed intermittent cytotoxicity and elicited lower levels of VEGF and angiogenin expression. PMID:25596932

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

    Science.gov (United States)

    Rojas, E; Taylor, R E

    1975-10-01

    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

  14. In-situ tracing of calcium silicate hydrate precipitation from high pH leachates by micro FT-IR

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Cementitious grout materials will be used to seal conductive fractures in the construction of a repository for the geological disposal of high-level radioactive waste. Expected reactions between groundwater and cementitious grouts will result in the formation and release of a chemically aggressive high pH plume. Such a high pH plume will likely cause the dissolution of primary and precipitation of secondary mineral phases in other barrier components. On the spatial and temporal scales of laboratory experiments, however, these mineral changes tend to be only slight and so their detection is problematic. The current study presents a new methodology of analyzing these mineral changes in-situ by micro Fourier transform infrared (FT-IR) spectroscopy. Under the experimental conditions tested, primary quartz dissolution and secondary calcium silicate hydrate (C-S-H) precipitation was observed and described in context of their reaction kinetics. An in-situ hydrothermal cell was constructed from titanium alloy with a diamond window to allow the transmission of an IR beam. The cell can be operated over a temperature range of 25-200 deg. C, a pressure range of 0.1-30 MPa, and can either be left sealed or connected to a fluid circulator. In the present study, a 0.0015-0.0038 g mixture of Ca(OH)2 and quartz (SiO2) powders were placed in the in-situ hydrothermal cell at a molar ratio = 1:1, with the remaining space filled with a Ca(OH)2 saturated solution (pH ≅ 12.5 at 25 deg. C, Ca ≅ 22 mM) to give a powder (g):solution (ml) ratio ∼ 1:1. The in-situ hydrothermal cell was then sealed and heated at 100, 120, 130, or 140 deg. C at a pressure of 3 MPa with IR spectra collected in the mid region every 5 minutes for 3.8-91 hours using a Jasco MFT 2000. An IR absorption band at 790 cm-1 was assigned to stretching vibration of Si-O in primary quartz and at 970 cm-1 to the stretching vibration of silanol (Si-OH) groups in

  15. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics

    International Nuclear Information System (INIS)

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C2S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C2S (27–30 nm) was prepared by solid state reaction at 1450 °C, while biphasic compound TCP/HAp (7–15 nm) was synthesized from an aqueous solution of Ca(NO3)2·4H2O and (NH4)2HPO4·12H2O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C2S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way. - Highlights: • The dissolution and hydration of β-C2S and TCP/HAp in distilled water and saline solution were studied. • TCP/HAp did not show mechanical strength, while β-C2S showed good mechanical strength. • The use of saline solution did enhances the dissolution & hydration rate. • An increase in pH values was detected when using saline solution. • Both materials showed a moderate cytotoxicity in no significant way

  16. Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

    Science.gov (United States)

    Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

    2016-06-01

    In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients ( L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient ( β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

  17. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Radwan, M.M., E-mail: mmahmoudradwan@yahoo.com [Ceramics Dept, National Research Centre, Cairo (Egypt); Abd El-Hamid, H.K. [Ceramics Dept, National Research Centre, Cairo (Egypt); Mohamed, A.F. [The Holding Company for Production of Vaccines, Sera and Drugs (EGYVAC) (Egypt)

    2015-12-01

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C{sub 2}S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C{sub 2}S (27–30 nm) was prepared by solid state reaction at 1450 °C, while biphasic compound TCP/HAp (7–15 nm) was synthesized from an aqueous solution of Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}·12H{sub 2}O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C{sub 2}S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way. - Highlights: • The dissolution and hydration of β-C{sub 2}S and TCP/HAp in distilled water and saline solution were studied. • TCP/HAp did not show mechanical strength, while β-C{sub 2}S showed good mechanical strength. • The use of saline solution did enhances the dissolution & hydration rate. • An increase in pH values was detected when using saline solution. • Both materials showed a moderate cytotoxicity in no significant way.

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

    Science.gov (United States)

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

    2014-06-01

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

  19. Electron Solvation in Liquid Ammonia: Lithium, Sodium, Magnesium, and Calcium as Electron Sources.

    Science.gov (United States)

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-03-10

    A free electron in solution, known as a solvated electron, is the smallest possible anion. Alkali and alkaline earth atoms serve as electron donors in solvents that mediate outer-sphere electron transfer. We report herein ab initio molecular dynamics simulations of lithium, sodium, magnesium, and calcium in liquid ammonia at 250 K. By analyzing the electronic properties and the ionic and solvation structures and dynamics, we systematically characterize these metals as electron donors and ammonia molecules as electron acceptors. We show that the solvated metal strongly modifies the properties of its solvation shells and that the observed effect is metal-specific. Specifically, the radius and charge exhibit major impacts. The single solvated electron present in the alkali metal systems is distributed more uniformly among the solvent molecules of each metal's two solvation shells. In contrast, alkaline earth metals favor a less uniform distribution of the electron density. Alkali and alkaline earth atoms are coordinated by four and six NH3 molecules, respectively. The smaller atoms, Li and Mg, are stronger electron donors than Na and Ca. This result is surprising, as smaller atoms in a column of the periodic table have higher ionization potentials. However, it can be explained by stronger electron donor-acceptor interactions between the smaller atoms and the solvent molecules. The structure of the first solvation shell is sharpest for Mg, which has a large charge and a small radius. Solvation is weakest for Na, which has a small charge and a large radius. Weak solvation leads to rapid dynamics, as reflected in the diffusion coefficients of NH3 molecules of the first two solvation shells and the Na atom. The properties of the solvated electrons established in the present study are important for radiation chemistry, synthetic chemistry, condensed-matter charge transfer, and energy sources. PMID:26886153

  20. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill e Part 2:Effects of mixing time and curing temperature

    Institute of Scientific and Technical Information of China (English)

    M. Kermani; F.P. Hassani; E. Aflaki; M. Benzaazoua; M. Nokken

    2015-01-01

    The effects of mixing time and curing temperature on the uniaxial compressive strength (UCS) and microstructure of cemented hydraulic fill (CHF) and sodium silicate-fortified backfill (Gelfill) were investigated in the laboratory. A series of CHF and Gelfill samples was mixed for time periods ranging from 5 min to 60 min and cured at temperatures ranging from 5 ?C to 50 ?C for 7 d, 14 d or 28 d. Increasing the mixing time negatively influenced the UCS of Gelfill samples, but did not have a detectable effect on CHF samples. The curing temperature had a strong positive impact on the UCSs of both Gelfill and CHF. An elevated temperature caused rapid UCS development over the first 14 d of curing. Mercury intrusion porosimetry (MIP) indicated that the pore size distribution and total porosity of Gelfill were altered by curing temperature.

  1. Atributos químicos de solos influenciados pela substituição do carbonato por silicato de cálcio Soil chemical properties influenced by the substitution of calcium carbonate by calcium silicate

    Directory of Open Access Journals (Sweden)

    Renato Ferreira de Souza

    2008-08-01

    ácia do silicato de Ca foi inferior à de carbonato de Ca na melhoria das condições químicas do solo.The application of silicates to soils can result in increased soil cation exchange capacity (CEC, displace anions, especially H2PO4- (diacid phosphate, neutralize the pH and Al toxicity and, in general, increase the nutrient availability to plants. However, calcium silicates may be less efficient than calcium carbonates. To evaluate the effect of calcium carbonate substitution by calcium silicate on the soil chemical properties, especially on phosphorus availability, four experiments were conducted in an entirely randomized design with four replications, in a greenhouse. The treatments consisted of five levels (0, 25, 50, 75, and 100 % of calcium carbonate substitution by calcium silicate, with a 4:1 Ca:Mg stoichiometric and the same amount of CaO, enough to reach a 60 % base saturation. The treatments were applied to 4 dm³ samples of a sandy orthic Quartzarenic Neosol (Quartzpsament, a sandy loam dystrophic Red-Yellow Latosol (Oxisol, sandy clay loam dystrophic Red-Yellow Latosol (Oxisol and a clayey dystrophic Red Latosol (Oxisol; each soil represented one experiment. The pH values in H2O, P, phosphorus in the equilibrium solution (P-rem, K, Ca, Mg, Si, Al, H + Al, organic matter (OM, Cu, Mn, Zn and B, sum of bases (S, effective (t ant total (T CEC, base saturation (V and Al saturation (m were submitted to analysis of variance and simple regression models fitted as a function of CaCO3 substitution by CaSiO3 levels. It was observed that carbonate substitution by silicate promoted significant increases in the values of Si, Al, H + Al and m and reduction in the values of P-rem, pH, S, t and V. The values of Mehlich 1 P, K, Mg, OM, T, Mn, Cu, and B were not influenced significantly. A reduction in Zn availability was verified in the dystrophic orthic Quartzarenic Neosol only. Calcium silicate was less efficient than calcium carbonate in the improvement of soil chemical

  2. Synthesis and nano-mechanical characterization of calcium-silicate-hydrate (C-S-H) made with 1.5 CaO/SiO2 mixture

    International Nuclear Information System (INIS)

    In this study, calcium silicate hydrate (C-S-H) is synthesized and characterized. C-S-H slurry was made with calcium oxide (CaO) to micro-silica (SiO2) mixture ratio of 1.5 and enough deionized water. The slurry was continuously mixed for 7 days, then the excess water was removed. Two methods of drying were implemented: one method used the standard d-dry technique and the other was equilibrated to 11% relative humidity (RH). The dried powders were characterized using thermo gravimetric analysis (TGA), X-ray diffraction analysis (XRDA), and 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The stoichiometric formulas of synthetic C-S-H powders dried to d-dry and 11% RH in this study were approximated as C1.2SH0.7 and C1.2SH2.4 respectively. The powders were then compacted to create specimens with porosities similar to C-S-H in hydrated cement. The specimens underwent nanoindentation to mechanically characterize C-S-H. The experiments provide insight on the nanoscale mechanical characteristics of C-S-H.

  3. Search for an exosphere in sodium and calcium in the transmission spectrum of exoplanet 55 Cancri e

    CERN Document Server

    Ridden-Harper, A R; Keller, C U; de Kok, R J; Di Gloria, E; Hoeijmakers, H J; Brogi, M; Fridlund, M; Vermeersen, B L A; van Westrenen, W

    2016-01-01

    [Abridged] The aim of this work is to search for an absorption signal from exospheric sodium (Na) and singly ionized calcium (Ca$^+$) in the optical transmission spectrum of the hot rocky super-Earth 55 Cancri e. Although current best-fitting models to the planet mass and radius require a possible atmospheric component, uncertainties in the radius exist, making it possible that 55 Cnc e could be a hot rocky planet without an atmosphere. High resolution (R$\\sim$110000) time-series spectra were analysed of five transits of 55 Cancri e, obtained with three different telescopes (UVES/VLT, HARPS/ESO 3.6m & HARPS-N/TNG). Targeting the sodium D lines and the calcium H and K lines the potential planet exospheric signal was filtered out from the much stronger stellar and telluric signals, making use of the change of the radial component of the orbital velocity of the planet over the transit from -57 to +57 km/sec. Combining all five transit data sets we detect a signal potentially associated with sodium in the pla...

  4. Statement on the exposure assessment of sodium stearoyl-2-lactylate and calcium stearoyl-2-lactylate including exposure resulting from extension of the authorisation of sodium stearoyl-2-lactylates

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS

    2013-03-01

    Full Text Available Following a request by the European Commission, the Scientific Panel on Food Additives and Nutrient Sources added to Food (ANS carried out an exposure assessment of sodium stearoyl-2-lactylate (E 481 and calcium stearoyl-2-lactylate (E 482 as a food additive, including an extension of the uses to use the additives in emulsified cooked meat products (e.g. mortadella, paté. Reflecting the data on actual use levels provided by food industry, the combined exposure to sodium stearoyl-2-lactylate and calcium stearoyl-2-lactylate is in the range 6-55 mg/kg bw/day for toddlers, 14-54 mg/kg bw/day for children, 13-27 mg/kg bw/day for adolescents, 4-16 mg/kg bw/day for adults, and 3-13 mg/kg bw/day for the elderly at the mean level. For exposure at high levels, ranges of 22-109 mg/kg bw/day for toddlers, 28-107 mg/kg bw/day for children, 21-46 mg/kg bw/day for adolescents, 15-33 mg/kg bw/day for adults, and 9-30 mg/kg bw/day were calculated for the elderly. The extension of the authorisation for the use of sodium stearoyl-2-lactylate in emulsified cooked meat products (e.g. mortadella, paté would not lead to an increase of exposure based on the approach taken for the exposure assessment for the two food additives.

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

    Science.gov (United States)

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

    2007-08-01

    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, τ, of the precipitated CaCO 3, from τ=55 s in the absence of additives, to τ 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, τ, 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 τ. 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 μm, as obtained in the control experiment, to sizes varying in the range 2-8 μm 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.

  6. Ecological comparison of calcium hydroxide and sodium hydrogen carbonate as sorbents; Oekologischer Vergleich der Sorptionsmittel Calciumhydroxid und Natriumhydrogencarbonat

    Energy Technology Data Exchange (ETDEWEB)

    Pacher, Christian; Weber-Blaschke, Gabriele [Technische Univ. Muenchen, Freising (Germany). Lehrstuhl fuer Rohstoff- und Energietechnologie; Mocker, Mario [ATZ Entwicklungszentrum, Sulzbach-Rosenberg (Germany); Faulstich, Martin [Technische Univ. Muenchen, Straubing (Germany). Wissenschaftszentrum Straubing

    2009-07-01

    Lime products have long been used with success for flue gas purification in waste incineration plants, where they serve to eliminate acid gas pollutants such as sulphur dioxide, hydrogen chloride and hydrogen fluoride. This article presents excerpts of a study commissioned by the German lime industry association for the purpose of obtaining an unbiased well-founded comparison of the environmental impact of the two sorbents calcium hydroxide and sodium hydrogen carbonate. The following questions were addressed by the study: Which of the two flue gas additives provides greater environmental benefit under specified conditions? What parameters influence the outcome? How can the results be viewed in regard to different plant configurations?.

  7. Adsorption of sodium polyacrylate at interface of dicalcium silicate-sodium aluminate solution%聚丙烯酸钠在硅酸二钙-铝酸钠溶液界面的吸附行为

    Institute of Scientific and Technical Information of China (English)

    于海燕; 潘晓林; 丁婷婷; 张武; 刘涵; 毕诗文

    2011-01-01

    The adsorption isotherm of sodium polyacrylate on dicalcium silicate (2CaO·SiO2) in sodium aluminate solution at 80 ℃ was studied.The type of surface adsorption of sodium polyacrylate is saturated adsorption,and the adsorption behavior belongs to L-type,according with the monolayer adsorption model of Langmuir equation.The surface coverage of sodium polyacrylate is 1.06 mol/μm2.The relation curve between the surface pressure and the molecular area of adsorption film was obtained by Gibbs formula.The variation of interracial energy caused by adsorption as well as the relationship between the relation curve and the type of adsorption was discussed.%测定了80℃时2CaO·SiO2 (C2S)在铝酸钠溶液中吸附聚丙烯酸钠(AY)的吸附量等温线.结果表明:AY在C2S表面的吸附类型为饱和吸附,吸附行为属“L”型,符合Langmuir方程单分子层吸附模型.结合C2S的比表面积可求出AY饱和吸附时表面覆盖度为1.06 mol/μm2.同时,运用Gibbs公式处理C2S在固-液界面的吸附结果,研究吸附膜的表面压力和分子面积的关系曲线,并讨论因吸附引起的固-液界面能变化规律以及曲线与吸附类型的关系.

  8. NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  9. Comparative evaluation of a dentifrice containing calcium sodium phosphosilicate to a dentifrice containing potassium nitrate for dentinal hypersensitivity: A clinical study

    Directory of Open Access Journals (Sweden)

    Tanya Satyapal

    2014-01-01

    Full Text Available Background: Calcium sodium phosphosilicate is a recently introduced desensitizing agent which acts by occluding the dentinal tubules and also resists acid decalcification. This study was designed to assess the efficacy of a new toothpaste containing 5% calcium sodium phosphosilicate for the treatment of dentinal hypersensitivity and also compare it with 5% potassium nitrate. Materials and Methods: Sixty patients with the chief complaint of dentinal hypersensitivity were enrolled and randomly divided into two groups. The visual analog scale (VAS scores were taken for water and air stimuli at baseline, 3 weeks after usage of the respective toothpaste, and 3 weeks after discontinuation of the respective toothpaste. Results: Both the groups showed reduction in hypersensitivity scores at 3 weeks and 6 weeks for air stimulus and cold water. The calcium sodium phosphosilicate group, however, showed significantly reduction in hypersensitivity compared to the potassium nitrate group at any time point for both measures of hypersensitivity. Conclusion: The 5% calcium sodium phosphosilicate group showed immense reduction in dentinal hypersensitivity symptoms. The 5% calcium sodium phosphosilicate showed prolonged effects even after discontinuation as compared to 5% potassium nitrate, due to its dentinal tubular occlusion property.

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

    Energy Technology Data Exchange (ETDEWEB)

    Morandeau, Antoine E.; White, Claire E. [Princeton

    2015-04-21

    Calcium–silicate–hydrate (C–S–H) gel is the main binder component in hydrated ordinary Portland cement (OPC) paste, and is known to play a crucial role in the carbonation of cementitious materials, especially for more sustainable alternatives containing supplementary cementitious materials. However, the exact atomic structural changes that occur during carbonation of C–S–H gel remain unknown. Here, we investigate the local atomic structural changes that occur during carbonation of a synthetic calcium–silicate–hydrate gel exposed to pure CO₂ vapour, using in situ X-ray total scattering measurements and subsequent pair distribution function (PDF) analysis. By analysing both the reciprocal and real-space scattering data as the C–S–H carbonation reaction progresses, all phases present during the reaction (crystalline and non-crystalline) have been identified and quantified, with the results revealing the emergence of several polymorphs of crystalline calcium carbonate (vaterite and calcite) in addition to the decalcified C–S–H gel. Furthermore, the results point toward residual calcium being present in the amorphous decalcified gel, potentially in the form of an amorphous calcium carbonate phase. As a result of the quantification process, the reaction kinetics for the evolution of the individual phases have been obtained, revealing new information on the rate of growth/dissolution for each phase associated with C–S–H gel carbonation. Moreover, the investigation reveals that the use of real space diffraction data in the form of PDFs enables more accurate determination of the phases that develop during complex reaction processes such as C–S–H gel carbonation in comparison to the conventional reciprocal space Rietveld analysis approach.

  11. Compositional Evolution of Calcium Silicate Hydrate (C-S-H) Structures by Total X-Ray Scattering

    KAUST Repository

    Soyer-Uzun, Sezen

    2011-12-09

    High-energy X-ray diffraction was employed to study the structural characteristics of a set of C-S-H samples with 0.6 ≤ C/S a;circ 1.75. It has been observed that Si is tetrahedrally coordinated to O for all samples irrespective of chemical composition and the Ca-O coordination number gradually decreases from ∼7 to ∼6 with increasing C/S ratio. This suggests that the C-S-H structure evolves from a tobermorite-like structure into a jennite-like structure as a function of increasing C/S ratio as the interlayer space decreases from ∼1.3 to ∼1 nm. Evolution of these short- and medium-range order structural characteristics in the C-S-H system is associated with the alteration of the Ca-O layers and silicate depolymerization with increasing C/S. © 2011 The American Ceramic Society.

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

    Science.gov (United States)

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

  13. The effect of calcium silicate on in vitro physiochemical properties and in vivo osteogenesis, degradability and bioactivity of porous β-tricalcium phosphate bioceramics

    International Nuclear Information System (INIS)

    Porous β-tricalcium phosphate(TCP)/calcium silicate(CS) composite bioceramics with different weight proportions were prepared to investigate the in vitro effects of CS on the physiochemical properties of TCP and the in vivo effects of CS on the degradability, osteogenesis and bioactivity of TCP. The physiochemical results showed that the addition of CS to porous TCP resulted in a looser and rougher surface and a lower solid density, compressive strength and Young's modulus and a lower pH value as compared to pure CS without any chemical interaction between the TCP and the CS. The in vivo study showed that the material degradation of porous TCP/CS composite bioceramics was slower than that of pure CS, although the osteogenesis, degradability and bioactivity were significantly increased in the long term. Thereafter, the introduction of CS into porous TCP bioceramics is an effective way to prepare bioactive bone grafting scaffolds for clinical use and to control properties such as in vivo degradability and osteoinduction of TCP. (paper)

  14. ToF-SIMS images and spectra of biomimetic calcium silicate-based cements after storage in solutions simulating the effects of human biological fluids

    Science.gov (United States)

    Torrisi, A.; Torrisi, V.; Tuccitto, N.; Gandolfi, M. G.; Prati, C.; Licciardello, A.

    2010-01-01

    ToF-SIMS images were obtained from a section of a tooth, obturated by means of a new calcium-silicate based cement (wTCF) after storage for 1 month in a saline solutions (DPBS), in order to simulate the body fluid effects on the obturation. Afterwards, ToF-SIMS spectra were obtained from model samples, prepared by using the same cement paste, after storage for 1 month and 8 months in two different saline solutions (DPBS and HBSS). ToF-SIMS spectra were also obtained from fluorine-free cement (wTC) samples after storage in HBSS for 1 month and 8 months and used for comparison. It was found that the composition of both the saline solution and the cement influenced the composition of the surface of disks and that longer is the storage greater are the differences. Segregation phenomena occur both on the cement obturation of the tooth and on the surface of the disks prepared by using the same cement. Indirect evidences of formation of new crystalline phases are supplied.

  15. A comparison in mechanical properties of cermets of calcium silicate with Ti-55Ni and Ti-6Al-4V alloys for hard tissues replacement.

    Science.gov (United States)

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Shirazi, Seyed Farid Seyed; Mehrali, Mehdi; Yau, Yat-Huang; Abu Osman, Noor Azuan

    2014-01-01

    This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements. PMID:25538954

  16. Improvements in the synthesis of zeolites with low Si/Al ratio from Venezuelan sodium silicate for an environmentally friendly process

    Directory of Open Access Journals (Sweden)

    A. García

    2016-04-01

    Full Text Available LTA and FAU zeolites were successfully synthesized from a Venezuelan sodium silicate solution, by hydrothermal crystallization under autogenous pressure at 100°C, with 2–24h crystallization times. The synthesized materials were characterized by XRD, BET specific surface area and SEM. A series of synthesis tests were performed to study the influence of the molar composition of the starting mixture over zeolites crystallization. The effect of crystallization time for a particular synthesis mixture composition was studied for both zeolites types. The reuse as alkaline medium of the mother liquor separated during filtration, and the effect of the aging before crystallization were additionally studied. The experimental result are in agreement with the crystallization mechanism proposed for zeolites synthesis in liquid phase. The use of a 2SiO2:Al2O3:6.Na2O:240H2O synthesis mixture composition allows obtaining LTA zeolite within 2h of crystallization. For FAU zeolite, no aging period was needed when starting with a 4SiO2:Al2O3:6.6Na2O:264H2O composition. It was possible to synthesize both zeolites with high purity and crystallinity and with adequate water adsorption properties.

  17. A continuous production process for silica aerogel powders based on sodium silicate by fluidized bed drying of wet-gel slurry

    International Nuclear Information System (INIS)

    The present study described a continuous process for the production of hydrophobic silica aerogel powders based on an inexpensive precursor such as sodium silicate. Fluidization technique was employed for the drying of wet-gel slurry at an ambient pressure. The fluidization column was fed with the silylated wet-gel slurry in a continuous mode and the fluidization was carried out at 220 C. The aerogel powder collected in Trap-I was fluidized twice at room temperature in order to separate the lighter aerogel particles from the first trap. The tapping density of the aerogel powder decreased from 0.09 to 0.05 g/cm3 for Trap-II, however, the microstructure did not differ significantly. Using this process, hydrophobic silica aerogel powders exhibiting tapping density as low as 0.05 g/cm3, high specific surface area of 783 m2/g and cumulative pore volume of 1.79 cm3/g have been obtained. The aerogels were characterized by Field-Emission Scanning Electron Microscopy (FE-SEM), BET specific surface area, N2 physi-sorption isotherms, pore size distribution and particle size analyses. The results have been compared with aerogel powders obtained by ambient pressure drying of the wet-gel slurry in a furnace. (authors)

  18. Functioning of catfish electroreceptors: Influence of calcium and sodium concentration on the skin potential

    OpenAIRE

    Schouten, V.J.A.; Bretschneider, F.

    1980-01-01

    1. 1. The skin potential of catfish was measured in order to test the hypothesis that it controls electroreceptor sensitivity. 2. 2. The skin potential depends on the “milieu extérieur” in the same way as reported lor goldfish (Fig. 2). 3. 3. The variation of the skin potential is very large compared with the normal stimulus range of electroreceptors. 4. 4. Calcium strongly influences the skin potential, but the latter “adapts” to calcium concentrations of 0.3-3.0 mM (Fig. 3). 5. 5. Ion-depen...

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

    International Nuclear Information System (INIS)

    The present work relates to the study of structural and elastic properties of Tobermorite 11 Å 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 Å 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 Å 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.

  20. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    OpenAIRE

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Robert J. Flatt; D'Espinose De Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measuremen...

  1. [Local tolerance of subcutaneous heparin. Double-blind comparison of calcium and sodium heparins (author's transl)].

    Science.gov (United States)

    Blard, J M; Rincon, F; Nakache, J P; Chastang, C

    One hundred and twelve subcutaneous injections of concentrated heparin (25,000 IU/ml), half in sodium heparin and half in calciparine, both with an identical heparin cation, were given in doses varying from 0.2 ml to 0.5 ml by a single operator in a double-blind study to assess the comparative local tolerance of the two heparin salts. The occurrence of bruising at the point of injection, more frequent with sodium heparin than with Calciparine, proved to be the distinguishing factor. Overall after 48 hours, 31 hematomas were observed with the sodium salt versus 20 with calciparine. McNemar's test of comparing matched proportions confirms this result (p = 0.03) and, with the order of the two treatments taken into consideration, J.J. Gart's exact test gives p = 0.0101. PMID:218296

  2. The Practice of Organic Ester Sodium Silicate Self-Hardening-Sand Technical Transformation%有机酯水玻璃自硬砂技术改造实践

    Institute of Scientific and Technical Information of China (English)

    朱童斌; 张良红; 王黎明

    2001-01-01

    本文介绍了有机酯水玻璃自硬砂技术改造的车间设计要点。成功开发出一种独具特色的非再生旧砂回收利用技术,该技术克服了水玻璃砂再生难的“瓶颈”制约,使生产成本大幅下降。通过对技术改造后的效果效益对比分析,证明了有机酯水玻璃自硬砂比原水玻璃七砂具有无可比拟的优势,是当今铸造车间技术改造的主导方向之一。%In this paper,the main design points of organic ester sodium silicate self-hardening-sand casting shop technical transfomation are introduced,anunusual technology of using no-reclamed sand is successfully developedm. It overcomes the “vaes-neck" restrict of sodium silicate sand reclamation, it maks the cost of productuon drop sharply, through analgsis comparison with benefit and resiut afrer technical transformation, it confirms organic estre sodium silicate self-hardening-sand has the great advantage than the old 70 sand,and it is one of the main technical transfomation direction of todays casting shop

  3. The Polarized Effect of Intracellular Calcium on the Renal Epithelial Sodium Channel Occurs as a Result of Subcellular Calcium Signaling Domains Maintained by Mitochondria.

    Science.gov (United States)

    Thai, Tiffany L; Yu, Ling; Galarza-Paez, Laura; Wu, Ming Ming; Lam, Ho Yin Colin; Bao, Hui Fang; Duke, Billie Jeanne; Al-Khalili, Otor; Ma, He-Ping; Liu, Bingchen; Eaton, Douglas C

    2015-11-27

    The renal epithelial sodium channel (ENaC) provides regulated sodium transport in the distal nephron. The effects of intracellular calcium ([Ca(2+)]i) on this channel are only beginning to be elucidated. It appears from previous studies that the [Ca(2+)]i increases downstream of ATP administration may have a polarized effect on ENaC, where apical application of ATP and the subsequent [Ca(2+)]i increase have an inhibitory effect on the channel, whereas basolateral ATP and [Ca(2+)]i have a stimulatory effect. We asked whether this polarized effect of ATP is, in fact, reflective of a polarized effect of increased [Ca(2+)]i on ENaC and what underlying mechanism is responsible. We began by performing patch clamp experiments in which ENaC activity was measured during apical or basolateral application of ionomycin to increase [Ca(2+)]i near the apical or basolateral membrane, respectively. We found that ENaC does indeed respond to increased [Ca(2+)]i in a polarized fashion, with apical increases being inhibitory and basolateral increases stimulating channel activity. In other epithelial cell types, mitochondria sequester [Ca(2+)]i, creating [Ca(2+)]i signaling microdomains within the cell that are dependent on mitochondrial localization. We found that mitochondria localize in bands just beneath the apical and basolateral membranes in two different cortical collecting duct principal cell lines and in cortical collecting duct principal cells in mouse kidney tissue. We found that inhibiting mitochondrial [Ca(2+)]i uptake destroyed the polarized response of ENaC to [Ca(2+)]i. Overall, our data suggest that ENaC is regulated by [Ca(2+)]i in a polarized fashion and that this polarization is maintained by mitochondrial [Ca(2+)]i sequestration. PMID:26451045

  4. Final report of the safety assessment of L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate as used in cosmetics.

    Science.gov (United States)

    Elmore, Amy R

    2005-01-01

    L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate function in cosmetic formulations primarily as antioxidants. Ascorbic Acid is commonly called Vitamin C. Ascorbic Acid is used as an antioxidant and pH adjuster in a large variety of cosmetic formulations, over 3/4 of which were hair dyes and colors at concentrations between 0.3% and 0.6%. For other uses, the reported concentrations were either very low (Ascorbate and Magnesium Ascorbate are described as antioxidants and skin conditioning agents--miscellaneous for use in cosmetics, but are not currently used. Sodium Ascorbyl Phosphate functions as an antioxidant in cosmetic products and is used at concentrations ranging from 0.01% to 3%. Magnesium Ascorbyl Phosphate functions as an antioxidant in cosmetics and was reported being used at concentrations from 0.001% to 3%. Sodium Ascorbate also functions as an antioxidant in cosmetics at concentrations from 0.0003% to 0.3%. Related ingredients (Ascorbyl Palmitate, Ascorbyl Dipalmitate, Ascorbyl Stearate, Erythorbic Acid, and Sodium Erythorbate) have been previously reviewed by the Cosmetic Ingredient Review (CIR) Expert Panel and found "to be safe for use as cosmetic ingredients in the present practices of good use." Ascorbic Acid is a generally recognized as safe (GRAS) substance for use as a chemical preservative in foods and as a nutrient and/or dietary supplement. Calcium Ascorbate and Sodium Ascorbate are listed as GRAS substances for use as chemical preservatives. L-Ascorbic Acid is readily and reversibly oxidized to L-dehydroascorbic acid and both forms exist in equilibrium in the body. Permeation rates of Ascorbic Acid through whole and stripped mouse skin were 3.43 +/- 0.74 microg/cm(2)/h and 33.2 +/- 5.2 microg/cm(2)/h. Acute oral and parenteral studies in mice, rats, rabbits, guinea pigs, dogs, and cats demonstrated little toxicity. Ascorbic Acid and Sodium Ascorbate acted

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

    Science.gov (United States)

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

  6. Regulation of physicochemical properties, osteogenesis activity, and fibroblast growth factor-2 release ability of β-tricalcium phosphate for bone cement by calcium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ching-Chuan [Antai Medical Care Cooperation Antai Tian-Sheng Memorial Hospital, Pingtung, Taiwan (China); Kao, Chia-Tze; Hung, Chi-Jr [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Chen, Yi-Jyun [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Dental Department, Taichung Hospital, Ministry of Health and Welfare, Taichung City, Taiwan (China); Huang, Tsui-Hsien, E-mail: thh@csmu.edu.tw [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [Institute of Oral Science, Chung Shan Medical University, Taichung, Taiwan (China)

    2014-04-01

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Formation of bone-like apatite, the diametral tensile strength, and weight loss of composites were considered before and after immersion in simulated body fluid (SBF). In addition, we also examined the effects of fibroblast growth factor-2 (FGF-2) released from β-TCP/CS composites and in vitro human dental pulp cell (hDPC) and studied its behavior. The results showed that the apatite deposition ability of the β-TCP/CS composites was enhanced as the CS content was increased. For composites with more than 50% CS contents, the samples were completely covered by a dense bone-like apatite layer. At the end of the immersion point, weight losses of 19%, 24%, 33%, 42%, and 51% were observed for the composites containing 0%, 30%, 50%, 70% and 100% β-TCP cements, respectively. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 70%, the amount of cells and osteogenesis protein of hDPCs was stimulated by FGF-2 released from β-TCP/CS composites. The combination of FGF-2 in degradation of β-TCP and osteogenesis of CS gives a strong reason to believe that these calcium-based composite cements may prove to be promising bone repair materials. - Highlights: • CS improved physicochemical properties and osteogenic activity of β-TCP. • The higher the CS in the cement, the shorter the setting time and the higher the DTS. • The cell behavior was stimulated by FGF-2 released from composite containing 50% CS. • β-TCP/CS composite with FGF-2 has optimal properties for

  7. Regulation of physicochemical properties, osteogenesis activity, and fibroblast growth factor-2 release ability of β-tricalcium phosphate for bone cement by calcium silicate

    International Nuclear Information System (INIS)

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Formation of bone-like apatite, the diametral tensile strength, and weight loss of composites were considered before and after immersion in simulated body fluid (SBF). In addition, we also examined the effects of fibroblast growth factor-2 (FGF-2) released from β-TCP/CS composites and in vitro human dental pulp cell (hDPC) and studied its behavior. The results showed that the apatite deposition ability of the β-TCP/CS composites was enhanced as the CS content was increased. For composites with more than 50% CS contents, the samples were completely covered by a dense bone-like apatite layer. At the end of the immersion point, weight losses of 19%, 24%, 33%, 42%, and 51% were observed for the composites containing 0%, 30%, 50%, 70% and 100% β-TCP cements, respectively. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 70%, the amount of cells and osteogenesis protein of hDPCs was stimulated by FGF-2 released from β-TCP/CS composites. The combination of FGF-2 in degradation of β-TCP and osteogenesis of CS gives a strong reason to believe that these calcium-based composite cements may prove to be promising bone repair materials. - Highlights: • CS improved physicochemical properties and osteogenic activity of β-TCP. • The higher the CS in the cement, the shorter the setting time and the higher the DTS. • The cell behavior was stimulated by FGF-2 released from composite containing 50% CS. • β-TCP/CS composite with FGF-2 has optimal properties for

  8. Acid-resistant calcium silicate-based composite implants with high-strength as load-bearing bone graft substitutes and fracture fixation devices.

    Science.gov (United States)

    Wei, Chung-Kai; Ding, Shinn-Jyh

    2016-09-01

    To achieve the excellent mechanical properties of biodegradable materials used for cortical bone graft substitutes and fracture fixation devices remains a challenge. To this end, the biomimetic calcium silicate/gelatin/chitosan oligosaccharide composite implants were developed, with an aim of achieving high strength, controlled degradation, and superior osteogenic activity. The work focused on the effect of gelatin on mechanical properties of the composites under four different kinds of mechanical stresses including compression, tensile, bending, and impact. The evaluation of in vitro degradability and fatigue at two simulated body fluid (SBF) of pH 7.4 and 5.0 was also performed, in which the pH 5.0 condition simulated clinical conditions caused by bacterial induced local metabolic acidosis or tissue inflammation. In addition, human mesenchymal stem cells (hMSCs) were sued to examine osteogenic activity. Experimental results showed that the appropriate amount of gelatin positively contributed to failure enhancement in compressive and impact modes. The 10wt% gelatin-containing composite exhibits the maximum value of the compressive strength (166.1MPa), which is within the reported compressive strength for cortical bone. The stability of the bone implants was apparently affected by the in vitro fatigue, but not by the initial pH environments (7.4 or 5.0). The gelatin not only greatly enhanced the degradation of the composite when soaked in the dynamic SBF solution, but effectively promoted attachment, proliferation, differentiation, and formation of mineralization of hMSCs. The 10wt%-gelatin composite with high initial strength may be a potential implant candidate for cortical bone repair and fracture fixation applications. PMID:27254281

  9. Mechanical and physical behavior of newly developed functionally graded materials and composites of stainless steel 316L with calcium silicate and hydroxyapatite.

    Science.gov (United States)

    Ataollahi Oshkour, Azim; Pramanik, Sumit; Mehrali, Mehdi; Yau, Yat Huang; Tarlochan, Faris; Abu Osman, Noor Azuan

    2015-09-01

    This study aimed to investigate the structural, physical and mechanical behavior of composites and functionally graded materials (FGMs) made of stainless steel (SS-316L)/hydroxyapatite (HA) and SS-316L/calcium silicate (CS) employing powder metallurgical solid state sintering. The structural analysis using X-ray diffraction showed that the sintering at high temperature led to the reaction between compounds of the SS-316L and HA, while SS-316L and CS remained intact during the sintering process in composites of SS-316L/CS. A dimensional expansion was found in the composites made of 40 and 50 wt% HA. The minimum shrinkage was emerged in 50 wt% CS composite, while the maximum shrinkage was revealed in samples with pure SS-316L, HA and CS. Compressive mechanical properties of SS-316L/HA decreased sharply with increasing of HA content up to 20 wt% and gradually with CS content up to 50 wt% for SS-316L/CS composites. The mechanical properties of the FGM of SS-316L/HA dropped with increase in temperature, while it was improved for the FGM of SS-316L/CS with temperature enhancement. It has been found that the FGMs emerged a better compressive mechanical properties compared to both the composite systems. Therefore, the SS-316L/CS composites and their FGMs have superior compressive mechanical properties to the SS-316L/HA composites and their FGMs and also the newly developed FGMs of SS-316L/CS with improved mechanical and enhanced gradation in physical and structural properties can potentially be utilized in the components with load-bearing application. PMID:26072197

  10. Effects of adsorbed and templated nanosilver in mesoporous calcium-silicate nanoparticles on inhibition of bacteria colonization of dentin

    Directory of Open Access Journals (Sweden)

    Fan W

    2014-11-01

    Full Text Available Wei Fan,1,* Daming Wu,1,* Franklin R Tay,2 Tengjiao Ma,1 Yujie Wu,1 Bing Fan1 1The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, People’s Republic of China; 2Department of Endodontics, Georgia Regents University, Augusta, Georgia, USA *These authors contributed equally to this work Abstract: Mesoporous calcium-silicate nanoparticles (MCSNs are advanced biomaterials for controlled drug delivery and mineralization induction. Nanosilver-incorporated MCSNs (Ag-MCSNs were prepared in the present study using both the adsorption and template methods. Both versions of Ag-MCSNs showed characteristic morphology of mesoporous materials and exhibited sustained release of ions over time. In antibacterial testing against planktonic Enterococcus faecalis, Ag-MCSNs showed significantly better antibacterial effects when compared with MCSNs (P<0.05. The Ag-MCSNs aggregated on the dentin surface of root canal walls and infiltrated into dentinal tubules after ultrasound activation, significantly inhibiting the adherence and colonization of E. faecalis on dentin (P<0.05. Despite this, Ag-MCSNs with templated nanosilver showed much lower cytotoxicity than Ag-MCSNs with adsorbed nanosilver (P<0.05. The results of the present study indicated that nanosilver could be incorporated into MCSNs using the template method. The templated nanosilver could release silver ions and inhibit the growth and colonization of E. faecalis both in the planktonic form and as biofilms on dentin surfaces as absorbed nanosilver. Templated Ag-MCSNs may be developed into a new intracanal disinfectant for root canal disinfection due to their antibacterial ability and low cytotoxicity, and as controlled release devices for other bioactive molecules to produce multifunctional biomaterials. Keywords: antibacterial effect, mesoporosity

  11. Chemical alteration of cement materials in a radioactive waste repository environment. 3. Development of reactive transport computational code combined with incongruent dissolution model of calcium silicate hydrates

    International Nuclear Information System (INIS)

    For long-term performance assessment of a cementitious disposal system for TRU waste, a so-called reactive transport computational code, being a numerical simulation code coupled a geochemical model suited to the system includes cement hydrate and a solute transport model, so-called reactive transport computational code, has been developed. The thermodynamic model previously developed in our institute for incongruent dissolution of calcium silicate hydrate (C-S-H) gel, which is a principal product of hydrated cement phase, was incorporated into a geochemical code, Harphrq, to evaluate chemical equilibrium conditions containing cement hydrates. This modification of the code enables a user to evaluate adequately the chemical equilibrium of a system including cement hydrate, such as a dissolution/precipitation of C-S-H gel and/or a change of Ca/Si ratio in C-S-H gel. The modified geochemical code was coupled onto a simplified solute transport code using a compartment model. The coupled code could simulate the processes where various chemical species in aqueous phase migrate through the homogeneous porous materials while locally maintaining chemical equilibrium. The developed reactive transport computational code was verified by comparison with experimental results on batch-type dissolution tests and column-type alteration tests under flow-through conditions of ordinary Portland cement hydrate. Predictive calculation results by the developed code were reasonably accordant with the experimental results, e.g. the distribution of constituent minerals and the composition of pore water in altered ordinary Portland cement hydrate. The validity of the developed code was therefore verified. Analysis on the results by the calculation could indicates special features such as a distribution of Ca/Si ratio in C-S-H gel along the water-flow in the column, and a re-precipitation of C-S-H gel in the downstream side of the dissolution front of C-S-H gel. (author)

  12. Effect of polymers on the nanostructure and on the carbonation of calcium silicate hydrates: a scanning transmission X-ray microscopy study

    KAUST Repository

    Ha, J.

    2011-09-07

    This study investigated the effects of organic polymers (polyethylene glycol and hexadecyltrimethylammonium) on structures of calcium silicate hydrates (C-S-H) which is the major product of Portland cement hydration. Increased surface areas and expansion of layers were observed for all organic polymer modified C-S-H. The results from attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic measurements also suggest lowered water contents in the layered structures for the C-S-H samples that are modified by organic polymers. Scanning transmission X-ray microscopy (STXM) results further supports this observation. We also observed difference in the extent of C-S-H carbonation due to the presence of organic polymers. No calcite formed in the presence of HDTMA whereas formation of calcite was observed with C-S-H sample modified with PEG. We suggest that the difference in the carbonation reaction is possibly due to the ease of penetration and diffusion of the CO 2. This observation suggests that CO 2 reaction strongly depends on the presence of organic polymers and the types of organic polymers incorporated within the C-S-H structure. This is the first comprehensive study using STXM to quantitatively characterize the level of heterogeneity in cementitious materials at high spatial and spectral resolutions. The results from BET, XRD, ATR-FTIR, and STXM measurements are consistent and suggest that C-S-H layer structures are significantly modified due to the presence of organic polymers, and that the chemical composition and structural differences among the organic polymers determine the extent of the changes in the C-S-H nanostructures as well as the extent of carbonation reaction. © 2011 Springer Science+Business Media, LLC.

  13. Interfacial Kinetics of High-Al-Containing Ultra-Lightweight Steels with Calcium Silicate-Based Molten Oxides at High Temperature

    Science.gov (United States)

    Kim, Gi Hyun; Sohn, Il

    2016-06-01

    The kinetics of the high-temperature reaction between high-Al- and -Mn-containing steels and synthesized molten calcium silicate-based fluxes from 1623 K to 1643 K (1350 °C to 1370 °C) was studied. Cylindrical steel rods were rotated in the molten fluxes for 300 to 1200 seconds at various temperatures below the melting point of the steels. The rods were connected to a rheometer, and the initial reaction rates were estimated from the torque variations. The dissolution of the steel into the molten slag was correlated to the variation in torque. The kinetics of the reaction between the rods and the slag estimated from the torque and subsequently from the viscosity were confirmed from the mass balance and from the variation in the chemical compositions of the rods and the molten slags, respectively. The liquid-phase mass transfer coefficient of Al2O3 was calculated to be 1.14 × 10-2 cm/s at 1623 K (1350 °C) and 1.52 × 10-2 cm/s at 1633 K (1360 °C). The kinetics calculated assuming liquid-phase mass transfer control was observed to be similar to the aforementioned kinetics determined from the dynamic viscosity variations. On the basis of dimensionless analysis of the Sherwood number (Sh = 0.05·Re0.65Sc0.31), liquid-phase mass transfer from the metal/flux interface was observed to be the rate-controlling step.

  14. Comparative evaluation of the remineralizing efficacy of calcium sodium phosphosilicate agent and fluoride based on quantitative and qualitative analysis

    Directory of Open Access Journals (Sweden)

    Saranya Mony

    2015-01-01

    Full Text Available Background: Calcium sodium phosphosilicate (NovaMin is an agent that is claimed to release calcium and phosphate ions intraorally to help the self-repair process of enamel. It is used extensively as a desensitizing agent, but the chemical reactions that occur may promote apatite formation enhancing remineralization. The present study was undertaken to evaluate the ability of NovaMin to remineralize an experimentally induced demineralized lesion. The evaluation was done based on the quantitative and qualitative analysis of enamel over the period of 15 and 30 days. Materials and Methods: A sample of 120 noncarious premolar teeth extracted for orthodontic reasons were used for the study. Baseline data for hardness, Ca/PO 4 , and surface characteristics before and after demineralization process was obtained. All the teeth were brushed twice daily at 12 h interval with the test agents using a powered toothbrush for 2 min. The samples were tested on the 15 th and 30 th day. Results: Calcium phosphate ratio and hardness in both the groups improved during the study period. Fluoride group showed higher values for Ca/PO 4 and hardness but was not statistically significant with the P > 0.05. Scanning electron microscope pictures showed that the deposition of the material over the decalcified enamel is more smoother and uniform with NovaMin and more irregular with fluoride. Relevance: NovaMin is found to be as effective in improving the Ca/PO 4 ratio and hardness in a demineralized enamel as fluoride. Hence, it can be a new alternate material for remineralization of enamel with less toxic effects compared to fluorides.

  15. Effect of Er{sub 2}O{sub 3} dopant on electrical and optical properties of potassium sodium niobate silicate glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yongsiri, Ploypailin [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sirisoonthorn, Somnuk [National Metal and Materials Technology Center, Pathumthani 12120 (Thailand); Pengpat, Kamonpan, E-mail: kamonpan.p@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-09-15

    Highlights: • The KNN–SiO{sub 2} doped Er{sub 2}O{sub 3} glass-ceramics was prepared by incorporation method. • High dielectric constant (458.41 at 100 kHz) and low loss (0.0005) could be obtained. • TEM and SEM confirmed the existence of KNN crystals embedded in glass matrix. • The Er{sub 2}O{sub 3} dopant causes insignificant effect on modifying E{sub g} value. - Abstract: In this study, transparent glass-ceramics from potassium sodium niobate (KNN)-silicate glass system doped with erbium oxide (Er{sub 2}O{sub 3}) were successfully prepared by incorporation method. KNN was added in glass batches as heterogeneous nucleating agent. The KNN powder was mixed with SiO{sub 2} and Er{sub 2}O{sub 3} dopant with KNN and Er{sub 2}O{sub 3} content varied between 70–80 and 0.5–1.0 mol%, respectively. Each batch was subsequently melted at 1300 °C for 15 min in a platinum crucible using an electric furnace. The quenched glasses were then subjected to heat treatment at various temperatures for 4 h. XRD results showed that the prepared glass ceramics contained crystals of KNN solid solution. In contrary, dielectric constant (ϵ{sub r}) and dielectric loss (tan δ) were found to increase with increasing heat treatment temperature. Additionally, optical properties such as absorbance and energy band gap have been investigated.

  16. Obtaining calcium silicates by using solid residues as precursors. Influence of water in the process of mixing reagents; Obtencin de silicatos de calcio empleando como precursores residuos solidos. Influencia del mezclado de reactivos en fase seca o fase humeda

    Energy Technology Data Exchange (ETDEWEB)

    Felipe-Sese, M.; Eliche-Quesada, D.; Corpas-Iglesias, F. A.

    2011-07-01

    The suitability of re-using residues marble, remaining from cutting marble, as a source of calcium-oxide, as well as the resultant ashes from the combustion of the wastes generated in the process of manufacturing boards from derivates of wood, as a source of silica, as raw material for the production of calcium silicate products has been determined. First of all, the influence of water has been studied in the initial phase of mixing residues. Marble and ashes have been mixed in molar relation CaO:SiO{sub 2} of 1:1 using two different ways: using a planetary ball mill (while in solid state) or agitating at 90 degree centigrade (2 h) using a 60 wt% of water (while in humid state). Later, both mixtures were sintered at 1100 degree centigrade (24 h). In order to use the obtained calcium-silicates as ceramic insulating thermal materials, the samples were compressed at 15 Tm obtaining bricks from which the technological properties have been studied. The ceramic materials obtained from mixing the residues in dry phase, as well as those obtained in the wet phase, can be used as thermal insulators, showing values of conductivity of 0.18 and 0.12 w/m{sup 2}K, with an elevated resistance to compressive strength. (Author) 14 refs.

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

    Science.gov (United States)

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

    1998-11-01

    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

  18. Quantitative study on La3+ influx mediated by sodium-calcium exchanger in human lymphocytes

    Institute of Scientific and Technical Information of China (English)

    WEI; Chunying(魏春英); YANG; Pin(杨频)

    2002-01-01

    Whether La3+ can enter human peripheral blood lymphocytes by the Na+/Ca2+ exchanger or not and the effect of La3+ on the Na+/Ca2+ exchanger activity are examined by fura-2 technique. And that whether La3+ is sequestered by intracellular organelles (mainly endoplasmic reticulum and mitochondria) is studied by this method. La3+ uptake is obviously stimulated by pretreating the cells with ouabain and by removing extracellular Na+, and intracellular La3+ concentration ([La3+]i) is directly proportional to its extracellular concentration ([La3+]o). But when [La3+]o exceeds 0.4 mmol/L, the 340/380 nm ratio of fluorescence is no longer varied and the maximum [La3+]i is 1.5×10-12 mol@L-1. The higher concentration of La3+ (0.1 mmol/L) increases Na+/Ca2+ exchange-mediated calcium influx, but lower concentration (10 mmol/L) appears to block calcium influx. The results also suggest that cytosolic La3+ is transported by the ATP-dependent Ca2+ pump. Intracellular Ca2+ stores are depleted by ionomycin, and then ionomycin is added again during the period of La3+ uptake, the 340/380 nm ratio of fluorescence is also increased, these results indicate that La3+ is sequestered by intracellular organelles. A characterization of fura-2-La3+ interaction in solution simulating intracellular ionic composition (pH 7.05) shows that La3+ forms a 1:1 fura-2-La3+complex, and the apparent dissociation constant of La3+ for fura-2 (Kd) is 1.7×10-12 mol@L-1. In addition, the limit of detection of fura-2 for La3+ and Ca2+ is 10?12 and 10?8 mol@L-1 respectively.

  19. COMPARISON OF SOL-GEL SILICATE COATINGS ON Ti SUBSTRATE

    Directory of Open Access Journals (Sweden)

    DIANA HORKAVCOVÁ

    2012-12-01

    Full Text Available The objective of the submitted work was to prepare and to characterize two types of silicate coatings prepared by the sol-gel method using the dip-coating technique on a titanium substrate. Efforts have been made to use mechanical properties of bio-inert titanium and bioactive properties of a silicate layer enriched with an admixture of compounds identified below. The first group consisted of silicate coatings containing silver, brushite and monetite. The other group of silicate coatings contained calcium nitrate and triethyl phosphate. Mechanically and chemically treated titanium substrates were dipped into sols and dried and fired. Silicate coatings from the first group were also chemically treated in 10 mol.l-1 solution of sodium hydroxide. All coatings were measured to determine their adhesive and bioactive properties and furthermore the antibacterial properties were tested in the case of first group. Surfaces of the coated substrates were investigated after the firing and after the individual tests with optical and electron microscopy and X-ray microdiffraction. A tape test demonstrated excellent adhesive property of all coatings to the substrate, classified with degree 5. A static in vitro test demonstrated bioactivity of nearly all the coatings. The basic silicate coating from the first group and one type of coating from the second group were identified as inert. Antibacterial properties of silicate coatings containing silver showed to be different when tested against Escherichia coli bacteria. A complete inhibition of the growth of bacteria under our experimental conditions was observed for the coating containing silver and monetite and a partial inhibition of the growth of bacteria for coatings containing silver and silver in combination with brushite.

  20. Influence of the redox state on the neptunium sorption under alkaline conditions. Batch sorption studies on titanium dioxide and calcium silicate hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Tits, Jan; Laube, Andreas; Wieland, Erich [Paul Scherrer Institute (PSI), Villigen (Switzerland). Lab. for Waste Management; Gaona, Xavier [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

    2014-07-01

    Wet chemistry experiments were carried out to investigate the effect of the redox state and aqueous speciation on the uptake of neptunium by titanium dioxide (TiO{sub 2}) and by calcium silicate hydrates (C-S-H) under alkaline conditions. TiO{sub 2} was chosen as a reference sorbent to determine the surface complexation behaviour of neptunium under alkaline conditions. C-S-H phases are important constituents of cement and concrete. They may contribute significantly to radionuclide retention due to their high recrystallization rates making incorporation the dominating sorption mechanism for many radionuclides (e.g. the actinides) on these materials. The sorption of neptunium on both solids was found to depend strongly on the degree of hydrolysis. On TiO{sub 2}R{sub d} values for Np(IV), Np(V) and Np(VI) are identical at pH = 10 and decrease with progressing hydrolysis in case of Np(V) and Np(VI). On C-S-H phases, R{sub d} values for the three redox states are also identical at pH = 10. While the R{sub d} values for Np(VI) sorption on C-S-H phases decrease with progressing hydrolysis, the R{sub d} values for Np(IV) and Np(V) sorption are not affected by the pH. In addition to the effect of hydrolysis, the presence of Ca is found to promote Np(V) and Np(VI) sorption on TiO{sub 2} whereas on C-S-H phases, the present wet chemistry data do not give unambiguous evidence. Thus, the aqueous speciation appears to have a similar influence on the sorption of the actinides on both types of solids despite the different sorption mechanism. The similar R{sub d} values for Np(IV,V,VI) sorption at pH = 10 can be explained qualitatively by invoking inter-ligand electrostatic repulsion between OH groups in the coordination sphere of Np(V) and Np(VI). This mechanism was proposed earlier in the literature for the prediction of actinide complexation constants with inorganic ligands. A limiting coordination number for each Np redox state, resulting from the inter-ligand electrostatic

  1. Influence of the redox state on the neptunium sorption under alkaline conditions. Batch sorption studies on titanium dioxide and calcium silicate hydrates

    International Nuclear Information System (INIS)

    Wet chemistry experiments were carried out to investigate the effect of the redox state and aqueous speciation on the uptake of neptunium by titanium dioxide (TiO2) and by calcium silicate hydrates (C-S-H) under alkaline conditions. TiO2 was chosen as a reference sorbent to determine the surface complexation behaviour of neptunium under alkaline conditions. C-S-H phases are important constituents of cement and concrete. They may contribute significantly to radionuclide retention due to their high recrystallization rates making incorporation the dominating sorption mechanism for many radionuclides (e.g. the actinides) on these materials. The sorption of neptunium on both solids was found to depend strongly on the degree of hydrolysis. On TiO2Rd values for Np(IV), Np(V) and Np(VI) are identical at pH = 10 and decrease with progressing hydrolysis in case of Np(V) and Np(VI). On C-S-H phases, Rd values for the three redox states are also identical at pH = 10. While the Rd values for Np(VI) sorption on C-S-H phases decrease with progressing hydrolysis, the Rd values for Np(IV) and Np(V) sorption are not affected by the pH. In addition to the effect of hydrolysis, the presence of Ca is found to promote Np(V) and Np(VI) sorption on TiO2 whereas on C-S-H phases, the present wet chemistry data do not give unambiguous evidence. Thus, the aqueous speciation appears to have a similar influence on the sorption of the actinides on both types of solids despite the different sorption mechanism. The similar Rd values for Np(IV,V,VI) sorption at pH = 10 can be explained qualitatively by invoking inter-ligand electrostatic repulsion between OH groups in the coordination sphere of Np(V) and Np(VI). This mechanism was proposed earlier in the literature for the prediction of actinide complexation constants with inorganic ligands. A limiting coordination number for each Np redox state, resulting from the inter-ligand electrostatic repulsion, allows the weaker sorption of the highest

  2. Chemical alteration of cement materials in a radioactive waste repository environment. 1. Thermodynamic modelling for the dissolution and precipitation of calcium silicate hydrates

    International Nuclear Information System (INIS)

    Cementitious material, a potential waste packaging and backfilling material for the disposal of radioactive waste, is expected to provide both physical and chemical containment. In particular the ability to provide high-pH conditions, which depends on the solubility of the constituent hydrated minerals in cement matrices, is a very important parameter when considering the release of radionuclides from radio active wastes. For long-term safety assessment, it is necessary to develop a series of predictive calculation models. Several models have been proposed for the incongruent dissolution of calcium silicate hydrate (C-S-H) gel, which is the principal product of hydrated cement phases. In the repository, the re-precipitation of minerals would follow their dissolution when an equilibrated solution moves to the other regions and equilibrates with the constituent minerals there. However, previous models have not yet adequately quantitatively evaluated the re-precipitation or interaction of other minerals with the dissolution of C-S-H gel. In this study, therefore, a thermodynamic dissolution and precipitation model of C-S-H gel is proposed assuming a binary non-ideal solid solution of Ca(OH)2 and Si02. Dissolution and precipitation experiments on C-S-H gel were performed. C-S-H precipitates were prepared using two techniques. One was based on hydrolysis in a mixture of Ca and Si solutions and produced homogeneous gels. With the other technique, precipitates were prepared by contacting Ca(OH)2 solution with C-S-H gel with low Ca/Si ratios (0.47, 0.65, 0.9). The results were well predicted by the proposed model. Dissolution experiments on C-S-H gel coexisting with ettringite were also carried out. At Ca/Si>l.2 in C-S-H gel, the equilibrated pH and Ca and Si concentrations are nearly the same as those for C-S-H gel alone. At lower Ca/Si, interaction between ettringite and C-S-H dissolution was observed more clearly. The measured pH and Ca and Si concentrations were

  3. Evaluation of a new calcium containing cardioplegic solution in the isolated rabbit heart in comparison to a calcium-free, low sodium solution.

    Science.gov (United States)

    Mori, F; Suzuki, K; Noda, H; Kato, T; Tsuboi, H; Miyamoto, M; Esato, K; Imamura, A; Kawahara, S; Uchiyama, J

    1991-03-01

    Isolated perfused rabbit hearts were studied to compare the effects of 3 hour ischemic arrest following either calcium-free or calcium-containing cardioplegia, on the recovery of isovolumic function of the left ventricle, coronary flow, release of creatine phosphokinase and myocardial water content. The hearts perfused with the calcium-containing solution (Ca 0.5 mmol/L) showed better recovery of the developed pressure in the left ventricle, and its first derivative and compliance. Coronary flow at a constant perfusion pressure was better restored during reperfusion in the hearts with calcium-containing solution. The release of less CPK and a lower water content were also observed in the hearts reperfused with calcium-containing solution. We concluded that calcium-containing cardioplegic solution with a high concentration of magnesium (10 mmol/L) was superior to calcium-free solution for myocardial protection. PMID:2051666

  4. Preparation and Phosphorus Recovery Properties of Porous Calcium Silicate Hydrate%多孔水化硅酸钙的制备及其磷回收特性

    Institute of Scientific and Technical Information of China (English)

    吉芳英; 关伟; 周卫威; 姜宁; 陈晴空; 晏鹏

    2013-01-01

    In order to sustainably utilize phosphorus,Carbide residue (as calcium material) and white carbon black (as silica material) was used to synthesize calcium silicate hydrate (CSH).As a crystal seed,CSH was used to recover phosphorus from wastewater by producing hydroxyapatite (HAP).The effect of Ca/Si molar ratio on the phosphorus recovery properties of CSH was studied.It was found that there were effects of Ca/Si molar ratio on the structure of CSH.When the Ca/Si molar ratio was 1.8∶ 1,the surface of prepared CSH presented porous structure.A good solubility of Ca2+ was obtained when the large area was used.The best operating condition to recover phosphorus by CSH were CSH dosage of 4 g/L,reaction time of 60 minutes,stirring intensity of 40 r/min.Under the optimum condition,the phosphorus content of regenerated products reached 17.56% after 15 times of circulation of phosphorus removal.This result indicated that the CSH material possessed good phosphorus recovery properties.According to X-ray diffraction and FTIR analysis,HAP has been formed on the surface of CSH during the phosphorus recovery process.In order to recover phosphorus,the CSH can be used to deal with the high phosphorus-contenting wastewater,including industrial wastewater and anaerobic rich phosphate supernatant.In addition,the regenerated phosphorus-containing products (HAP),instead of precious and depleting phosphorus resource,can be reused as phosphorus rock and phosphorus fertilizer.%为实现磷资源的可持续利用,以环境废弃物电石渣为钙质材料,以白碳黑为硅质材料合成CSH(水化硅酸钙),以该材料为晶种,以结晶形成羟基磷灰石的形式从含磷废水中回收磷,重点研究了不同钙硅比[c(CaO) /c(SiO2)]条件下制备的CSH对含磷废水中磷的回收特性.结果表明,钙硅比为1.8∶1时所得的CSH结构更疏松、表面分布有较多的孔隙,较大的比表面积使其具有较好的溶钙能力.钙硅比为1.8∶1的CSH最佳磷回

  5. Midbrain dopaminergic neurons generate calcium and sodium currents and release dopamine in the striatum of pups

    Directory of Open Access Journals (Sweden)

    Constance Hammond

    2012-03-01

    Full Text Available Midbrain dopaminergic neurons (mDA neurons are essential for the control of diverse motor and cognitive behaviors. However, our understanding of the activity of immature mDA neurons is rudimentary. Rodent mDA neurons migrate and differentiate early in embryonic life and dopaminergic axons enter the striatum and contact striatal neurons a few days before birth, but when these are functional is not known. Here, we recorded Ca2+ transients and Na+ spikes from embryonic (E16-E18 and early postnatal (P0-P7 mDA neurons with dynamic two photon imaging and patch clamp techniques in slices from tyrosine hydroxylase-GFP mice, and measured evoked dopamine release in the striatum with amperometry. We show that half of identified E16-P0 mDA neurons spontaneously generate non-synaptic, intrinsically-driven Ca2+ spikes and Ca2+ plateaus mediated by N- and L-type voltage-gated Ca2+ channels. Starting from E18-P0, half of the mDA neurons also reliably generate overshooting Na+ spikes with an abrupt maturation at birth (P0 = E19. At that stage (E18-P0, dopaminergic terminals release dopamine in a calcium-dependent manner in the striatum in response to local stimulation. We propose that the intrinsic spontaneous activity of mouse mDA neurons may impact the development/activity of the striatal network from birth.

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

    Science.gov (United States)

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

    1980-01-01

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

  7. Effects of surface application of dolomitic limestone and calcium-magnesium silicate on soybean and maize in rotation with green manure in a tropical region

    OpenAIRE

    2015-01-01

    Although lime is currently the material most frequently used to ameliorate soil acidity in Brazil, silicate could efficiently replace this source because of its greater solubility and its greater silicon content, which are beneficial for plant development. This study aimed to evaluate the effects of superficial lime and silicate application on soil chemical attributes as well as on soybean and maize nutrition and grain yields when these crops are grown in rotation with green manure. The exper...

  8. The effect of sodium silicate concentration on microstructure and corrosion properties of MAO-coated magnesium alloy AZ31 in simulated body fluid

    OpenAIRE

    B. Salami; Afshar, A.; Mazaheri, A.

    2014-01-01

    In recent years, magnesium and its alloys are considered as biodegradable implants. However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed. In this investigation, micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid. Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current. The effects of silicate concentration and conductivity...

  9. Biochemistry of the normal dura mater of the human brain determination of water, sodium, potassium, calcium, phosphorus, magnesium, copper, iron, sulfur and nitrogen contents

    Directory of Open Access Journals (Sweden)

    Horacio M. Canelas

    1969-06-01

    Full Text Available The concentrations of water, sodium, potassium, calcium, phosphorus, magnesium, copper, iron, sulfur, and nitrogen were determined in samples of apparently normal dura mater removed from 18 subjects recently dead by craniocerebral trauma. The average concentrations expressed in dry weight were: water 79.55 g/100 g ± 2.52; sodium 1.63 mequiv/100 g ±0.27; potassium 3.68 mequiv/100 g ± 0.66; calcium 119.84 mg/100 g ± 107.40; phosphorus 68.2 mg/100 g ± 34.5; magnesium 0.61 mequiv/100 g ± 0.37; copper 249.8 /xg/100 g ± 109.4; iron 0.82 mg/100 g ± 0.28; sulfur 490.7 mg/100 g ± 22.5; nitrogen 3.33 g/100 g ± 0.17.

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

    Science.gov (United States)

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

    2015-09-01

    We map out calcium II and sodium I absorption (Fraunhofer H, K & D lines) induced by both the interstellar medium and the circumgalactic medium of the Milky Way. Our measurements cover more than 9000 deg2 and make use of about 300 000 extragalactic spectra from the Sloan Digital Sky Survey. We present absorption maps for these two species and then compare their distributions to those of neutral hydrogen and dust. We show that the abundance of Na I with respect to neutral hydrogen stays roughly constant in different environments, while that of Ca II decreases with hydrogen column density. Studying how these tracers vary as a function of velocity, we show that, on average, the NNaI/NCaII ratio decreases at higher velocity with respect to the local standard of rest, similar to the local Routly-Spitzer effect but seen on Galactic scale. We show that it is likely caused by higher gas/dust density at lower velocity. Finally, we show that Galactic Ca II and Na I absorption needs to be taken into account for precision photometry and, more importantly, for photometric redshift estimation with star-forming galaxies. Our maps of Ca II and Na I absorption are publicly available.

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

    International Nuclear Information System (INIS)

    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 ≤ 21 mol %) glassy matrix by heat treatment. Initial magnetization curves reveal that samples with x = 6 and 9 mol % zinc-iron oxide exhibit both ferrimagnetic and paramagnetic contributions, whereas, samples with x > 9 mol % zinc-iron oxide exhibit only ferrimagnetic contribution. This observation is supported by the disappearance of the electron paramagnetic resonance (EPR) absorption line centered at g ∼ 4.3 in samples with x > 9 mol % zinc-iron oxide. Apatite-forming ability of the glass-ceramic samples was investigated by examining apatite formation on the surface of the samples treated in simulated body fluid (SBF). Increase in apatite-forming ability was observed with an increase in zinc-iron oxide content. The results obtained have been used to understand the evolution of the apatite surface layer as a function of immersion time in SBF and glass-ceramic composition. A good correlation has also been observed between the magnetic nature of the samples and their apatite-forming ability. These materials are expected to find application as thermo-seeds in hyperthermia treatment of bone cancer.

  12. Effect of Compounding of Sodium Tripolyphosphate and Super Plasticizers on the Hydration of α-calcium Sulfate Hemihydrate

    Institute of Scientific and Technical Information of China (English)

    PAN Wei; WANG Peiming

    2011-01-01

    The inhibition and its mechanism of sodium tripolyphosphate(STP)composited with super plasticizers(SPs)on hydration of α-calcium sulfate hemihydrate were studied by setting time,strength,hydration heat,X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),electronic probe micro analysis (EPMA),scanning electron microscopy(SEM)and differential scanning calorimeter(DSC)measurements.The experimental results show that compared with STP addition,compositing STP with polycarboxylate(PC)plasticizer,the final setting time is prolonged from 0.5h to 2hs.While formulating STP with naphthalene-based plasticizer(NAP)or sulfonate melamine formaldehyde plasticizer(SMF),the final setting time is reduced to quarter of an hour Similar changes can also be found in the rate of exothermic hydration and hydration degree.Formulating STP with suitable addition of PC can enhance the strength,while compositing STP and NAP or SMF weakens the strength.Besides,adding STP or STP and SMF,obvious movement(more than lev)of binding energy of Ca2p1/2 and Ca2p3/2 is detected.Compared with STP addition,content of the characteristic element(P)of STP is cut down form 1.1% to 0.49% by compositing STP with SMF.Furthermore,as hydration age increases,hydration inhibition in the presence of admixtures weakens and even disappears within 56 h.

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

    CERN Document Server

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

    2015-01-01

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

  14. Ab Initio Discovery of Novel Crystal Structure Stability in Barium and Sodium-Calcium Compounds under Pressure using DFT

    CERN Document Server

    Taillon, Joshua A; Hennig, Richard G

    2012-01-01

    Group I/II materials exhibit unexpected structural phase transitions at high pressures, providing potential insight into the origins of elemental superconductivity. We present here a computational study of elemental barium and binary sodium-calcium alloys to identify both known and unknown phases of barium under pressure, as well as stable high-pressure compounds in the immiscible Na-Ca system. To predict stability, we performed density functional theory calculations on randomly generated structures and evolved them using a genetic algorithm. For barium, we observed all of the expected phases and a number of new metastable structures, excluding the incommensurate Ba-IV structure. We also observed a heretofore unreported structure (\\alpha-Sm) predicted to be the ground state from 30-42 GPa. In the Na-Ca system, we demonstrate feasibility of our search method, but have been unable to predict any stable compounds. These results have improved the efficacy of the genetic algorithm, and should provide many promisin...

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

    OpenAIRE

    Maryam Moezizadeh; Azar Alimi

    2014-01-01

    Aim: The purpose was to compare the effect of 0.2% sodium fluoride mouthwash and casein phosphopeptide-amorphous calcium phosphate paste on prevention of dentin erosion. Materials and Methods: Buccal surfaces of 36 sound premolar teeth were ground flat and polished with abrasive discs. Half the polished surfaces were covered with tape to maintain a reference surface. Samples were randomly allocated into three groups. Group A was pretreated with tooth mousse (TM) 4 times a day for 5 days. ...

  16. Subcutaneous calcium heparin versus intravenous sodium heparin in treatment of established acute deep vein thrombosis of the legs: a multicentre prospective randomised trial.

    OpenAIRE

    Walker, M. G.; Shaw, J W; Thomson, G J; Cumming, J G; Thomas, M. L.

    1987-01-01

    One hundred patients with phlebographically proved acute deep vein thrombosis of the legs were prospectively randomised into two treatment groups to compare the safety and efficacy of subcutaneous calcium heparin versus intravenous sodium heparin administered by constant infusion pump. The dose of heparin was determined by daily measurement of the kaolin cephalin clotting time. Treatment was maintained for up to 14 days, after which phlebography was repeated. Of 49 patients who received subcu...

  17. Subcutaneous calcium heparin versus intravenous sodium heparin in treatment of established acute deep vein thrombosis of the legs: a multicentre prospective randomised trial.

    Science.gov (United States)

    Walker, M G; Shaw, J W; Thomson, G J; Cumming, J G; Thomas, M L

    1987-05-01

    One hundred patients with phlebographically proved acute deep vein thrombosis of the legs were prospectively randomised into two treatment groups to compare the safety and efficacy of subcutaneous calcium heparin versus intravenous sodium heparin administered by constant infusion pump. The dose of heparin was determined by daily measurement of the kaolin cephalin clotting time. Treatment was maintained for up to 14 days, after which phlebography was repeated. Of 49 patients who received subcutaneous calcium heparin, two showed an increase in thrombus size, while eight showed complete lysis. In the 47 patients who received intravenous sodium heparin thrombus increased in size in 13 while only one showed evidence of complete lysis. These differences were significant. There were no significant differences between the two groups in the incidence of serious complications, although almost half of those receiving intravenous heparin had some minor problem with the constant infusion pump and just over half of those receiving subcutaneous heparin had some bruising at the injection site. This study showed that subcutaneous calcium heparin was more effective in helping lyse existing thrombus and preventing its propagation than intravenous sodium heparin. PMID:3109574

  18. Scientific Opinion on the safety assessment of the active substances iron powder, activated carbon, calcined kaolin, sodium chloride, polyacrylic acid, sodium salt, crosslinked and calcium chloride, for use as active system in food contact materials

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2014-05-01

    Full Text Available This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety assessment of the active substances iron powder, activated carbon, calcined kaolin, sodium chloride, polyacrylic acid, sodium salt, crosslinked and calcium chloride, used in mixture which is packed into labels, for absorbing oxygen from the headspace surrounding packed food. All substances of this formulation have been evaluated and approved for use as additives in plastic food contact materials or as food supplements. Migration of substances from the labels and formation and release of volatile constituents are not expected under the intended conditions of use. The CEF Panel concluded that the use of substances iron powder, activated carbon, calcined kaolin, sodium chloride, polyacrylic acid, sodium salt, crosslinked and calcium chloride does not raise a safety concern when used in oxygen absorbers in labels, which prevent the physical release of their content into the food. When placed in the headspace of the packaging or when used in direct contact with foods, the labels should not intentionally or unintentionally come into direct contact with liquid foods or foods that have an external aqueous phase on the surface such as sliced fruits.

  19. NON-AUTOCLAVE SILICATE BRICK

    Directory of Open Access Journals (Sweden)

    V. N. Yaglov

    2015-01-01

    Full Text Available The paper proposes a technology for obtaining bricks on the basis of lime-silica mixtures where chemical interactions are practically completely realized in dispersive state at the stage of preparation of binding contact maturing and raw mixture as a whole. The role of forming operation (moulding is changed in principle because in this case conversion of dispersive system into a rock-like solid occurs and due to this the solid obtains complete water-resistance in contact with water immediately after forming operation. Theoretical basis for the developed technology is capability of silicate dispersive substances (hydrated calcium silicate to transit in non-stable state, to form a rock-like water-resistant solid in the moment of mechanical load application during forming process. Specific feature of the proposed method is an exclusion of additional operations for autoclaving of products from the process of obtaining a silicate brick.Synthetic hydrated calcium silicate in contrast to natural ones are more uniform in composition and structure, they contain less impurities and they are characterized by dispersive composition and due to the mentioned advantages they find wider practical application. Contact-condensation binders permit to manipulate product properties on their basis and ensure maximum correspondence to the requirements of the concrete application. Raw material sources for obtaining synthetic hydrated calcium silicates are practically un-limited because calcium-silicon containing substances are found as in various technogenic wastes so in natural compounds as well. So the problem for obtaining hydrated calcium silicates having contact-condensation ability for structure formation becomes more and more actual one. This transition is considered as dependent principally on arrangement rate of substance particles which determined the level of its instability.

  20. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk;

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...... affected the ash chemistry and the ash sintering tendency but much less the char reactivity. Thermo balance test are made and high-temperature X-ray diffraction measurements are performed, the experimental results indicate that with calcium addition major inorganic¿inorganic reactions take place very late...... calcium binds silicon primarily as calcium silicates and less as potassium calcium silicates....

  1. Genetic control and transgressive segregation of zinc, iron, potassium, phosphorus, calcium, and sodium accumulation in cowpea (Vigna unguiculata) seeds.

    Science.gov (United States)

    Fernandes Santos, C A; Boiteux, L S

    2015-01-01

    Cowpea crop, through combining a range of essential minerals with high quality proteins, plays an important role in providing nutritional security to human population living in semi-arid regions. Studies on genetics of biofortification with essential minerals are still quite scarce, and the major objective of the present study was to provide genetic information on development of cowpea cultivars with high seed mineral contents. Genetic parameters heritability and minimum number of genes were estimated for seed accumulation of zinc (Zn), iron (Fe), calcium (Ca), phosphorus (P), potassium (K), and sodium (Na). Generation mean and variance analyses were conducted using contrasting parental lines, F₁, F₂, and backcross populations derived from IT97K-1042-3 x BRS Tapaihum and IT97K-1042-3 x Canapu crosses. High narrow-sense heritability (h²) values were found for accumulation of Fe (65-86%), P (74-77%), and K (77-88%), whereas moderate h(2) values were observed for accumulation of Ca (41-56%), Zn (51-83%), and Na (50-55%) in seeds. Significant additive genetic effects as well as parental mean effects were detected in both crosses for all minerals, whereas epistasis was important genetic component in Zn content. The minimum number of genes controlling the accumulation of minerals ranged from two (K) to 11 (P). Transgressive segregation was observed in F2 populations of both crosses for all minerals analyzed. The results suggest that, although under either oligogenic or polygenic control, the seed content of these six minerals in cowpea can be improved via standard breeding methods largely used for self-pollinated crops. PMID:25729958

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

    International Nuclear Information System (INIS)

    Metabolic balance studies were undertaken to determine whether sodium bicarbonate (NaHCO3) supplements (4.5 mmol/day) altered 7-day cumulative calcium (Ca) phosphorus (P) balances in growing rats consuming either a basal diet providing 0.6% Ca and 0.3% P, or this diet plus 1,25-dihydroxycholecalciferol [40 ng 1,25(OH)2D3/day]. Feeding bicarbonate lowered urinary Ca but raised fecal Ca so that Ca balance became less positive. However, 1,25(OH)2D3 increased net absorption of Ca and P to the same degree when given to control rats and rats consuming bicarbonate. Nevertheless, bicarbonate-fed rats had lower net Ca absorption than controls, even when treated with high doses of 1,25(OH)2D3. Changes in net Ca absorption induced by bicarbonate may occur at a point in the gut distal to the duodenum since duodenal 45Ca absorption was decreased by bicarbonate feeding. The present results show that bicarbonate consumption depressed net Ca absorption in the rat. The effect appears to be independent of changes in 1,25(OH)2D3 metabolism because it is manifest in animals receiving high doses of 1,25(OH)2D3, which stimulate alimentary Ca absorption maximally, and because bicarbonate-fed rats are able to respond normally to exogenous 1,25(OH)2D3 by increasing their net absorption of Ca and P. In view of this demonstration that NaHCO3 supplements elevate fecal Ca loss in the rat, it is suggested that studies should be undertaken to determine whether bicarbonate exerts similar adverse effects on Ca balance in humans

  3. Dealkalization of calcium silicate slag and study of using it as cement admixture%硅钙渣脱碱处理及作水泥混合材的研究

    Institute of Scientific and Technical Information of China (English)

    刘江; 张建波; 孙俊民; 王宏霞; 叶家元; 史迪

    2012-01-01

    Orthogonal experiment method is applied to research on dealkalization of calcium silicate slag, and properties of non-dealkalizated and dealkalizated calcium slag cement have been analyzed. Effects of temperature, holding time, content of lime milk and washing times were discussed, the results show that the optimum dealkalization combination of the four factors is as follows:content of lime milk is 10%,temperature 85 X. and holding time 3 hours,washing twice,then an alkali content of 0.83% will be acquired; compressive strength of non梔ealkalizated calcium slag cement is higher than dealkalizated calcium slag cement during the early hydration, the advantages of dealkalizated calcium slag cement will gradually appear as time goes and will be more significantly as calcium slag content increase; Microscopic analysis shows that non-dealkalizated calcium slag cement generates large amount of C-S-H gel during early hydration and its hydration products are more compact than dealkalizated calcium slag cement, little difference of the compactness has been found between them when the hydration time is 28 days.%采用正交试验法对硅钙渣进行脱碱处理,对脱碱前后的硅钙渣水泥性能进行了研究.通过调整温度、保温时间、石灰乳掺量和水洗次数,得出最佳脱碱组合为:石灰乳掺量10%,温度85℃,保温时间3h,水洗2次,处理后碱含量为0.83%:强度试验结果表明,水化早期未脱碱硅钙渣水泥抗压强度要高于脱碱硅钙渣水泥,但随着龄期逐渐增长,脱碱硅钙渣水泥优势逐渐显现,掺量越大优势越明显;微观形貌分析表明,未脱碱硅钙渣水泥水化早期生成大量C-S-H凝胶,水化产物较脱碱硅钙渣水泥更致密,水化28d时两者水化产物的致密性相当.

  4. Calcium and potassium silicates and the growth of Eucalyptus grandis seedlings Aplicação de silicatos de cálcio e de potássio e o crescimento de mudas de Eucalyptus grandis

    Directory of Open Access Journals (Sweden)

    Itamar Antonio Bognola

    2011-06-01

    Full Text Available

    The use of silicate is a practice that has been frequently adopted in annual crops, although few studies have been conducted in order to verify its efficiency in forest tree species. The main objective of this research was to evaluate the effect of calcium and potassium silicates in the growth of seedlings of Eucalyptus grandis. The experiment was conducted in a greenhouse, in Alambari county, State of São Paulo. A completely randomized experimental design was adopted, with eight treatments, three replications and 25 plants per plot, maintained at the field capacity moisture level. Seedlings were planted in plastic tubes using local substrate, basic fertilization and silicates. Diameter, height and fresh and dry biomass of the seedlings were determined 150 days after silicates treatments were applied. The use of silicates either in the substrate or through foliar application, in the production of eucalypt seedlings has proven to be inadequate when the substrate presents a balanced basic composition in terms of nutrients and pH.

    doi: 10.4336/2011.pfb.31.66.83

    O uso de silicato é uma prática que vem sendo adotada com frequência em culturas anuais, muito embora poucos trabalhos tenham sido realizados com intuito de verificar sua eficiência em espécies florestais arbóreas. O objetivo principal desta pesquisa foi avaliar o efeito da aplicação de silicatos de cálcio e de potássio no crescimento de mudas de Eucalyptus grandis. O experimento foi conduzido em casa de vegetação, no Município de Alambari, SP. O delineamento usado foi inteiramente ao acaso, com oito tratamentos, três repetições e 25 plantas por parcela, sendo mantidas na umidade de capacidade de campo. As mudas foram plantadas em tubetes de plástico, utilizando substrato local, com adubação básica e silicatos. Diâmetro de colo, altura e biomassa verde e seca das mudas foram determinados 150 dias após a

  5. SODIUM ENVIRONMENTS IN GLASS

    OpenAIRE

    Greaves, G.

    1981-01-01

    Sodium environments have been measured directly in several oxide glasses using EXAFS at the sodium K edge. The existence of local structure around sodium in glass contradicts the conventional Zachariasen model. Analysis of the EXAFS indicates there are significant differences relating to the glass modifier : glass former chemistry - the details of which demonstrate similarities with crystalline silicates and borates.

  6. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate.

    Science.gov (United States)

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition to the side effects mentioned above by different channel blockers, these drugs can cause arterial wall damage, thereby contributing to vascular wall structure destabilization and promoting events facilitating rupture of plaques. Collagen synthesis is regulated by ascorbic acid, which is also essential for its optimum structure as a cofactor in lysine and proline hydroxylation, a precondition for optimum crosslinking of collagen and elastin. Therefore, the main objective in this study was to evaluate effects of various types of channel blockers on intracellular accumulation and cellular functions of ascorbate, specifically in relation to formation and extracellular deposition of major collagen types relevant for vascular function. Effects of select Na- and Ca- channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen I ECM deposition. Nifedipine (50 µM), a representative of channel blockers tested, significantly reduced ascorbic acid and ascorbyl palmitate-dependent ECM deposition of collagen type l and collagen type lV by cultured aortic smooth muscle cells. In addition, nifedipine (50 µM) significantly reduced ascorbate-dependent collagen type l and type lV synthesis by cultured aortic smooth

  7. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate

    Science.gov (United States)

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition to the side effects mentioned above by different channel blockers, these drugs can cause arterial wall damage, thereby contributing to vascular wall structure destabilization and promoting events facilitating rupture of plaques. Collagen synthesis is regulated by ascorbic acid, which is also essential for its optimum structure as a cofactor in lysine and proline hydroxylation, a precondition for optimum crosslinking of collagen and elastin. Therefore, the main objective in this study was to evaluate effects of various types of channel blockers on intracellular accumulation and cellular functions of ascorbate, specifically in relation to formation and extracellular deposition of major collagen types relevant for vascular function. Effects of select Na- and Ca- channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen I ECM deposition. Nifedipine (50 µM), a representative of channel blockers tested, significantly reduced ascorbic acid and ascorbyl palmitate-dependent ECM deposition of collagen type l and collagen type lV by cultured aortic smooth muscle cells. In addition, nifedipine (50 µM) significantly reduced ascorbate-dependent collagen type l and type lV synthesis by cultured aortic smooth

  8. Use of sodium or calcium salts of fatty acids as sources of energy in buffalo rations during late pregnancy

    International Nuclear Information System (INIS)

    Thirty pregnant buffaloes expected to calve within 60-75 days were divided into three groups balanced by bodyweight and expected date of parturition. The first group received a control ration consisting of concentrate diet (75% concentrate feed mixture with 25% yellow corn) plus berseem (Trifolim alexandrinum) hay and rice straw. In the second and third groups, yellow corn was replaced with either sodium salts of fatty acids (Na-SFA) or calcium salts of fatty acids (Ca-SFA). The content of acid ether extract (AEE) in Ca-SFA was lower than that of Na-SFA, while TFA's in Ca-SFA were higher. Degradability rates of dry matter (DM), organic matter (OM), crude protein (CP), effective degradability (ED) and potential degradability (PD) decreased with the ration containing Na-SFA. Undegradable values of DM, OM and CP increased with adding Na-SFA compared with adding Ca-SFA or the control diet. Digestion coefficients of DM, OM, CP and cell wall constituents (CWC) were lower with feeding the ration containing Na-SFA compared with that containing Ca-SFA, while no significant differences were found between the control and Ca-SFA-containing rations. Values for total digestible nutrients (TDN) and digestible crude protein (DCP) were reduced (P < 0.05) with the ration contained Na-SFA compared with Ca-SFA. Feed intake was not affected by feeding rations containing Na-SFA or Ca-SFA, but bodyweight (BWt) was higher after feeding rations containing Ca-SFA or Na-SFA compared with the control. pH values, propionic acid and free fatty acids (FFA's) in the rumen were higher (P < 0.05) when feeding the ration containing Na-SFA compared with that containing Ca-SFA or the control, while total volatile fatty acids (TVFAs), acetic, Ac:Pr ratio and NH3-N were significantly decreased. Adding Na-SFA in the ration decreased glucose and total protein concentrations in blood compared with Ca-SFA or in the control. Concentrations of albumin, globulin and their ratio were not affected with feeding

  9. Scientific Opinion on the safety and efficacy of malic acid and a mixture of sodium and calcium malate when used as technological additives for all animal species

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2014-02-01

    Full Text Available An application has been made for the re-authorisation of malic acid as a preservative in feed and an acidity regulator in feed for cats and dogs and for the authorisation of a mixture of sodium and calcium salts of malic acid to be used as an acidity regulator in feed for all animal species. Evidence from feeding studies with dogs, poultry, piglets, veal calves and ruminants showed that the highest typical use level of 1 600 mg malic acid/kg complete feedingstuffs (supplied as acid or salts is safe for all animal species. Setting a maximum content was not considered as necessary. Malic acid and its sodium and calcium salts are permitted food additives without limit in the EU. The use of malic acid and its sodium and calcium salts in animal nutrition is safe for the consumer. Malic acid and its salts are considered as strongly irritant to the skin and mucosa and as a particular risk to the eyes. Exposure via inhalation for those handling the additives is also considered to present a risk. Malates are components of the diet of humans and animals and are rapidly and completely metabolised to CO2. Consequently, their use in animal production would not pose a risk to the environment. Malic acid is used in food as a preservative. It is reasonable to expect that the effect seen in food will be observed in feed when it is used at comparable concentrations and under similar conditions. However, the FEEDAP Panel has reservations about the effectiveness of malic acid as a preservative in complete feedingstuffs with a moisture content of ≤ 12 %. The ability of malic acid and its salts to act as acidity regulators in feed has not been demonstrated.

  10. Reduction of sodium and increment of calcium and ω-3 PUFA in dry fermented sausages: effects on the mineral content, lipid profile and sensory quality

    OpenAIRE

    Garcia-Iñiguez-de-Ciriano, M. (Mikel); Berasategi, I. (Izaskun); Navarro-Blasco, I. (Íñigo); Astiasaran, I. (Iciar); D. Ansorena

    2012-01-01

    BACKGROUND: A combined technological approach was applied in the development of healthier dry fermented sausages: a partial substitution of the pork back fat by pre-emulsified linseed oil and a partial replacement of sodium chloride with calcium ascorbate at two different levels, leading to low amounts of salt (14gSalt and 10gSalt, with 14 g and 10 g NaCl per kg of mixture, respectively). RESULTS: The developed products (14gSalt and 10gSalt) showed adequate results for a(w) (0.85 and...

  11. Scientific Opinion on the re-evaluation of sodium stearoyl-2-lactylate (E 481) and calcium stearoyl-2-lactylate (E 482) as food additives

    OpenAIRE

    EFSA Panel on Food Additives and Nutrient Sources added to food (ANS)

    2013-01-01

    Following a request by the European Commission, the Panel of Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion on the safety of sodium stearoyl-2-lactylate (E 481, SSL) and calcium stearoyl-2-lactylate (E 482, CSL) when used as food additives. SSL and CSL are used as emulsifiers and stabilizers. An Acceptable Daily Intake (ADI) of 20 mg/kg bw/day for SSL and CSL (either singly or in combination) was established in 1974 by the Joint FAO/WHO Exper...

  12. 基于电位法的水玻璃模数自动测定方法及仪器%Automatically determining modulus of sodium silicate and its instrument using potentiometry

    Institute of Scientific and Technical Information of China (English)

    刘蒙; 樊自田; 汪华方

    2011-01-01

    Method and instrument were introduced which could automatically determine the modulus of the sodium silicates based on potentiometry. The potential signals were collected by signal acquisition unit consisted of the antimony electrode and the temperature sensor.Micro-peristaltic pump was used to liquid fill and titrate solution.The STM32F103 microcontroller was exploited to control the titration process and carry out the data processing.Magnetic heating stirrer was applied to heat and mix the solution.The results show that the method and instrument can determine the modulus of the sodium silicate automatically,fleetly and accurately.%在遵循水玻璃模数测定原理的基础上,提出了一种基于电位法的水玻璃模数自动测定方法并设计了相关仪器,采用金属锑电极和温度传感器组成的信号采集单元采集到的电位信号取代传统的指示剂判断滴定终点;采用微型蠕动泵对待测溶液进行精确加液滴定代替手工加液滴定;采用STM32F103微控制器控制整个滴定过程并进行数据处理;采用磁力加热搅拌器对整个滴定过程进行加热搅拌.试验结果表明采用该方法及仪器可以自动、快速、准确测定水玻璃模数.

  13. A contribution of research by chlorination from nickel silicate and nickel ferrite in the presence of calcium chloride and coke with possibilities of their intensification

    OpenAIRE

    Krstev, Boris

    1988-01-01

    The previous investigations in the field of the metal compounds chlorination of the refractory nickel minerals: garnierite and nontronite, by the chlorine, Cl2, HCl, NaCl or CaCl2, were determined directions, confirming the perspective of the mentioned process for the treatment of the low grade and complex minerals-laterites. The existing combined methods for enriching of the oxide-silicate nickel ores are these through which by heating the ore with coke and CaCl2 at high temperature reduced...

  14. A PRELIMINARY INVESTIGATION INTO THE USE OF ACID-TOLERANT PRECIPITATED CALCIUM CARBONATE FILLERS IN PAPERMAKING OF DEINKED PULP DERIVED FROM RECYCLED NEWSPAPER

    Directory of Open Access Journals (Sweden)

    Jing Shen

    2009-08-01

    Full Text Available The use of acid-tolerant precipitated calcium carbonate fillers, including phosphoric acid/sodium hexametaphosphate modified precipitated CaCO3 filler, and sodium silicate/phosphoric acid/sodium hexametaphos-phate modified precipitated CaCO3 filler in papermaking of deinked pulp derived from recycled newspaper was explored. These two acid-tolerant fillers provided considerably more brightness improvement in papers in comparison the unmodified filler, presumably indicating alleviated pulp darkening achieved as a result of better acid-resistant properties. The addition of acid-tolerant fillers into the furnish slurries gave lower system pH as compared with unmodified filler. Among the three fillers used in this work, the effect on retention of modification of the filler with sodium silicate/phosphoric acid/sodium hexametaphosphate was probably the best, as evaluated from ash content measurements. For air permeability of the paper, the use of acid-tolerant fillers provided slightly more improvement in comparison to the unmodified filler. For tensile and burst strength of the paper, the use of sodium silicate/phosphoric acid/sodium hexameta-phosphate modified precipitated calcium carbonate filler gave better results as compared with the other two fillers. Additionally, the improving effect of acid-tolerant fillers on furnish static drainage was found to be slightly weaker than that of unmodified filler.

  15. Avaliação de cultivares de alface adubadas com silicato de cálcio em casa-de-vegetação Evaluation of lettuce cultivars fertilized with calcium silicate in greenhouse

    Directory of Open Access Journals (Sweden)

    Regina Lúcia Félix Ferreira

    2010-10-01

    Full Text Available O experimento foi conduzido no Departamento de Ciência do Solo da Universidade Federal de Lavras - UFLA, no período de junho a agosto de 2002. Objetivou-se avaliar a produtividade, o estado nutricional e a qualidade (classe de tamanho de cultivares de alface cultivadas com doses de silicato de cálcio em vasos sob casa-de-vegetação. O delineamento experimental foi em blocos casualizados, com quatro repetições, com 1 planta/vaso, em esquema fatorial 3 x 4 + 3, sendo três cultivares de alface (Raider, Regina e Vera e quatro doses de silicato de cálcio (0, 410, 1,000 e 2,000 mg dm-3; os tratamentos adicionais foram compostos pela aplicação de 820 mg dm-3 de carbonato de cálcio, para as três cultivares. O estado nutricional das plantas de alface foi avaliado pelo Sistema Integrado de Diagnose e Recomendação (DRIS. A aplicação da fonte silicato de cálcio não aumentou o crescimento das plantas e não aumentou o teor dos nutrientes nas plantas de alface, mas melhorou a nutrição das plantas para Si e aumentou a porcentagem de plantas sadias. A aplicação também aumentou a concentração de Mn, devido ao alto conteúdo de Mn no fertilizante aplicado (Silifértil®. As três variedades de alface comportaram-se como plantas não acumuladoras de Si.The experiment was carried out at the Department of Soil Sciences of the Universidade Federal de Lavras - UFLA, from June to August 2002, with the objective to evaluate the productivity, the nutritional state and the quality (size class of lettuce cultivars grown with calcium silicate in greenhouse. The experimental design was disposed in blocks with four replicates, in factorial arrangement with additional treatments: 3 x 4 +3, composed by three lettuce cultivars: Raider (group crisphead lettuce; Regina (group butterhead lettuce and Vera (group looseleaf lettuce and four calcium silicate rates (0, 410, 1.000 and 2.000 mg dm-3, additional treatments were composed of the application of

  16. Silicate fertilizer and irrigation depth in corn production

    OpenAIRE

    Edvaldo Eloy Dantas Júnior; Lucia Helena Garófala Chaves; Fernando Antônio Melo da Costa; Hans Raj Gheyi

    2013-01-01

    Calcium-magnesium silicates improve the soil physicochemical properties and provide benefits to plant nutrition, since they are sources of silica, calcium and magnesium. The objective of this study was to evaluate the grain yield of irrigated corn fertilized with calcium-magnesium silicate. The experiment was carried out in a greenhouse in Campina Grande - PB, Brazil, using plastic pots containing 80 kg of soil. The treatments consisted of the combination of four irrigation depths, related to...

  17. Characterization of silicates and calcium carbonates applied to high-dose dosimetry; Caracterizacao de silicatos e carbonatos de calcio aplicados a dosimetria de doses altas

    Energy Technology Data Exchange (ETDEWEB)

    Vila, Gustavo Barreto

    2012-07-01

    The predominant isomorphous form in the biominerals studied in this work (oyster shell, coral, mother of pearl and shell) was aragonite. The appearance of the calcite phase occurred at 500 deg C at a heating rate of 10 deg {sup C}/s for all samples except for the coral sample, which was 400 deg C, independent of the heating rate. The most abundant element in the biominerals samples was Ca in the CaO form, and in the silicates (tremolite, diopside and rhodonite) Si in the SiO form. The most common trace element observed in the biominerals samples was Fe. The analyses of electron paramagnetic resonance showed lines of Mn{sup 2+} in the coral and mother-of-pearl samples before irradiation. In the case of the irradiated samples, the defects found were CO{sub 2}{sup -}, CO{sub 3}{sup 3-}, CO{sub 3}{sup -} and SO{sub 2}{sup -}, in the g range between 2.0010 and 2.0062. In the analyses by optical absorption of biominerals, transitions due to the presence of Mn in the samples were found. A thermoluminescent (TL) peak at approximately 140 deg C was found for the biominerals and at 180 deg C for silicates, which intensity depends directly on the dose. For samples exposed to different types of radiation, the TL peak occurred at lower temperatures. From the dose-response curves obtained for these materials, it was possible to determine a linear range for which their application in high dose dosimetry becomes possible. Taking into account the radiation type, among biominerals and silicates, the lowest detectable dose (40mGy) to gamma radiation was achieved for oyster shell samples using the measuring technique of optically stimulated luminescence (OSL). Using beta radiation, for diopside and tremolite samples the lowest detectable dose of 60mGy was obtained. For all samples, using the TL, OSL and thermally stimulated exoelectron emission (TSEE) techniques in alpha, beta and gamma radiation beans a good response reproducibility was obtained. Therefore, the samples characterized

  18. Experimental study on preparation of sodium silicate by purification of gangue and alkali melting activation%煤矸石除杂及碱融活化制取硅酸钠的实验研究

    Institute of Scientific and Technical Information of China (English)

    孔德顺; 吴红

    2013-01-01

    研究利用煤矸石中的硅元素制取硅酸钠,先将煤矸石粉在750℃下煅烧2h,除去有机质并破坏了煤矸石中的高岭石等矿物的晶型结构,再将煅烧过的煤矸石粉在95℃、液固比(mL/g)为8:1、质量分数为40%的硫酸中酸浸5h,煤矸石煅烧粉中的铁和铝等金属杂质离子的总去除率为86.93%;还研究了碱融活化条件对硅元素溶出率的影响,获得了适宜的碱融活化条件:m(酸浸粉):m(碳酸钠)=1:1.5、碱融温度为800 ℃、碱融时间为2h.在此条件下,硅元素溶出率大于75%,最终获得了硅酸钠溶液.%In order to utilize silicon in the coal gangue to prepare sodium silicate,the gangue powder was calcined at 750 ℃for 2 h firstly,then the organic matters were removed and the crystal structures of the minerals,such as kaolin in the gangue were destroyed.The calcined gangue powder was leached in sulfuric acid with mass fraction of 40% and liquid to solid ratio of 8:l at 95 ℃ for 5 h.The total removal ratio of impurity metal ions,such as iron and aluminum was 86.93%;the influences of the alkali melting activation conditions on the dissolution ratios of silicon element were investigated,then the suitable activation conditions were obtained:the mass ratio of acid leaching powder to sodium carbonate was 1:1.5,the alkali melting temperature was 800 ℃,and the alkali melting time was 2 h.Under these conditions silicon element dissolution ratio was more than 75% and the sodium silicate solution was obtained finally.

  19. Alleviating negative effects of irrigation-water salinity on growth and vase life of gerbera by foliar spray of calcium chloride and potassium silicate

    OpenAIRE

    A. Mohammadi Torkashvand

    2015-01-01

    The required water for greenhouses in Kishestan, Soume-e-Sara town, Guilan province, Iran, is mainly provided by underground resources that have inappropriate quality. One way to reduce the impact of salinity an plant growth is proper nutrition. This greenhouse research was conducted to evaluate the effect of water salinity and foliar spray of calcium (Ca) and silicon (Si) on growth and vase life of gerbera in a factorial experiment based on compeletly randomized design with two factors. The ...

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

    Directory of Open Access Journals (Sweden)

    Maryam Moezizadeh

    2014-01-01

    Full Text Available 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.

  1. 活性硅酸钙在高填料文化用纸中的应用研究%Application research of activated calcium silicate in high ifller ifne paper

    Institute of Scientific and Technical Information of China (English)

    崔樵夫; 刘廷志; 杨波

    2015-01-01

    研究了活性硅酸钙作为填料在高填料文化用纸中的应用。所用硅酸钙填料来源于电厂粉煤灰,平均粒径为31.90µm,是一种偏碱性、带有较强负电荷、高分散新型硅酸盐产品。以针叶木浆和阔叶木浆为纤维原料,在打浆度45°S R情况下,以40/60的比例进行混合,采用阳离子玉米淀粉和两性聚丙烯酰胺的双元增强助留体系,抄造出来的纸样在活性硅酸钙填料的添加量为35%时,各项指标均达到了国家静电复印纸标准(GB/T 24988-2010)规定要求。在针叶木浆与废纸浆的混合比例达到50/50时,采用同样的抄造方法也可以达到以上标准要求。在此基础上,在小长网试验纸机上,以针叶木浆/阔叶木浆(40/60)为原料进行抄纸试验,按照CS (1.5%)、AmCPAM(0.8%)、CPAM(0.03%)、AKD(0.5%)、填料(74%)的顺序加入各种助剂,抄造出的纸样在活性硅酸钙填料的添加量达到35%时,其白度、紧度、施胶度、不透明度、撕裂度、耐折度、抗张强度、弯曲挺度等各项指标均能够满足国家标准要求。%Application of activated calcium silicate as papermaking ifller for high ifller ifne papers was studied in this article. The activated calcium silicate was extracted from fine coal ash which is produced from thermal power plant. Calcium silicate ifller is a kind of negatively charged, alkaline, high dispersion product with mean particle diameter of 31.90µm. The performances of the handsheet could meet the requirements of the national standards for copy paper(GB/T 24988-2010), while the bleached soft wood KP pulp and hard wood pulp (40/60) was used as ifber stock and the ash content of the handsheet was 35%. The same results were obtained when the bleached softwood kraft pulp and deinked pulp (ratio 50/50) was used. Cationic starch and AmCPAM, comprising a binary retention system, were employed in handsheet making. The pilot

  2. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates.

    Science.gov (United States)

    Pustovgar, Elizaveta; Sangodkar, Rahul P; Andreev, Andrey S; Palacios, Marta; Chmelka, Bradley F; Flatt, Robert J; d'Espinose de Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of (29)Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966

  3. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    Science.gov (United States)

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; D'Espinose de Lacaillerie, Jean-Baptiste

    2016-03-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.

  4. Flotabilidade da apatita e minerais de ganga provenientes de minério sílico-carbonatado com oleato de sódio Floatability of apatite and gangue minerals from silicate-carbonate ores with sodium oleate

    Directory of Open Access Journals (Sweden)

    Michelly dos Santos Oliveira

    2010-09-01

    Full Text Available O beneficiamento dos minérios fosfáticos com ganga silicatada e carbonatada é estritamente necessário para aumentar a produção de concentrados fosfáticos e para suprir a demanda nacional de fertilizantes. Visando a processar esses minérios, esse trabalho estudou, através de testes de microflotação e medidas de potencial zeta, o efeito do oleato de sódio, do amido de milho e da carboximetilcelulose (CMC na superfície dos minerais puros originários do minério sílico-carbonatado de Catalão/GO. Os resultados obtidos mostraram a possibilidade de separação seletiva da apatita, por flotação direta em pH igual a 9, usando-se oleato de sódio como coletor, na ausência de depressores, o que seria inviável industrialmente. Tanto a CMC como o amido deprimem a dolomita, mas não são seletivos, pois deprimem, também, a apatita. O amido apresenta ação depressora sobre a apatita mais forte que a CMC.The processing of phosphate ores containing silicates and carbonates in the gangue is strictly necessary to increase phosphate rock production to meet the Brazilian demand for fertilizers. Aiming at the processing of these ores, this investigation addressed, via microfl otation and zeta potential determinations, the effect of sodium oleate, corn starch and carboxymethylcellulose (CMC on the surfaces of pure minerals from the Catalão/GO silicate-carbonate deposit. The results suggested the possibility of selective apatite concentration via direct fl otation at pH = 9, using sodium oleate as collector, in the absence of depressants; a route that would be industrially unfeasible. Both, CMC and starch, act as dolomite depressants, but the action is not selective, for apatite is also depressed by these reagents. Starch is a stronger apatite depressant than CMC.

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

    Directory of Open Access Journals (Sweden)

    Sonali Taneja

    2014-01-01

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

  6. Effect of temperature on hydration kinetics and polymerization of tricalcium silicate in stirred suspensions of CaO-saturated solutions

    International Nuclear Information System (INIS)

    Tricalcium silicate was hydrated at 274, 278, 283, 298, and 313 K in stirred suspensions of saturated CaO solutions under a nitrogen-gas atmosphere until the end of deceleratory period. The suspension conductivities and energy flows were measured continuously. The individual reaction rates for tricalcium silicate dissolution, calcium silicate hydrate precipitation, and calcium hydroxide precipitation were calculated from these measurements. The results suggest that the proportion of tricalcium silicate dissolved was determined by the rate of tricalcium silicate dissolution and the time to very rapid calcium hydroxide precipitation. The time to very rapid calcium hydroxide precipitation was more sensitive to changes in temperature than was the rate of tricalcium silicate dissolution, so that the proportion of tricalcium silicate hydration dissolved by the deceleratory period increased with decreasing temperature. The average chain length of the calcium silicate hydrate ascertained by magic-angle spinning nuclear magnetic resonance spectroscopy increased with increasing temperature

  7. Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of fast breeder reactors

    International Nuclear Information System (INIS)

    Highlights: • Concrete aggregates were exposed to liquid sodium exposure at 550 °C. • Thermal and chemical effects were studied using megascopic and micro-analytical techniques. • Aggregates underwent significant thermo-chemical degradation upon exposure. • Limestone found more suitable for sodium environment than siliceous aggregate. - Abstract: Sodium is used as an efficient coolant in fast breeder reactor (FBR) for extracting nuclear heat from its high power density core to steam generator, to produce electricity. Accidentally spilled Sodium at elevated temperatures of 550 °C or above may interact with concrete leading to its deterioration. A sacrificial concrete layer is provided on the structural concrete to mitigate the harmful impacts of these interactions. Locally available crushed rocks like limestone and granite are employed as aggregates in sacrificial and structural concrete respectively. Rocks are naturally occurring multi-mineral and multiphase inorganic systems of the earth. Aggregates are the main constituents of concrete accounting for 70–80% of its mass. In this paper, an attempt is made to study the physico-chemical modifications that may occur in the aggregates during the interactions between liquid sodium and the aggregates of concrete. The experimental strategy consists of heating of granite, limestone and river sand aggregates at 550 °C for 30 min and further treating them with 1 Normal aqueous solution of NaOH, to differentiate thermal and chemical effects. Furthermore, sodium-aggregate interaction study at 550 °C was conducted to characterize the combined effects of heat and sodium. Siliceous aggregates (granite and river sand) were found to be easily attacked by ferric oxidation during heating in air and also subjected to rapid chemical reactions with liquid NaOH, producing mineral phases of sodium silicate, sodium orthosilicates, calcium orthosilicates and sodium carbonates. Initiation and propagation of cracking in the

  8. Development and in vitro evaluation of an oral floating matrix tablet formulation of calcium di-sodium EDTA using gamma scintigraphy

    International Nuclear Information System (INIS)

    Full text: Heavy metal poisoning remains a widespread problem in most industrial nations. People exposed to these heavy metal while come in contact heavy metal industries. Toxicity is more likely to result through inhalation or ingestion route. It affects a number of important body functions including central nervous and haematopoietic systems, besides hepatic and renal functions. Metal toxicity has also been reported to cause oxidative stress, leading to various physiological malfunctions. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. In order to overcome above mentioned problem we have developed a floating drug delivery system of Calcium disodium edetate (CaNa2EDTA) to provide prolong chelation therapy against various heavy metals. Floating matrix tablets of Ca Na2EDTA were found to attain prolonged gastric residence time. A radiolabeling procedure of Ca-disodium-EDTA with 99mTc was standardized using stannous chloride as reducing agent. The radiolabeled complex was added to the optimized tablet. Floating tablets were prepared by wet granulation technique, using polymers such as Hydroxy propyl methyl cellulose (HPMC, Methocel K100M CR), sodium alginate, Chitosan alone or in combination and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. The effects of sodium bicarbonate and poly vinyl alcohol on drug release profile and floating properties were investigated. Dissolution studies were performed to ensure that there was no leaching of radioactivity from the capsules. Gamma scintigraphy was performed in healthy human volunteers to assess the buoyancy of the optimized formulation. The optimized formulation remained buoyant during 4 hours of gamma scintigraphic studies in rabbits

  9. Effect of Soaking on Calcium, Phosphorus, Magnesium and Sodium Contents of Chickpea (Cicer aritinum L.)

    OpenAIRE

    Reza Mahdavi; Anita Kazem Shayan; Seyed Jamal Ghaemmaghami; Elnaz Faramarzi

    2012-01-01

    The aim of this study was to evaluate the effect of soaking on peas minerals. Raw peas were soaked for 8, 12 and 24 h in tap water. After drying and acid digestion, 70 samples in 4 groups of raw, 8, 12 and 24 h soaked and also soaking waters of all soaking hours, minerals were measured and compared. The result of present study showed that after 12 and 24 soaking hours, calcium content of peas and after 8, 12 and 24 h soaking time, magnesium and phosphorus content of samples were decreased and...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-05-01

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

  11. Alleviating negative effects of irrigation-water salinity on growth and vase life of gerbera by foliar spray of calcium chloride and potassium silicate

    Directory of Open Access Journals (Sweden)

    A. Mohammadi Torkashvand

    2015-11-01

    Full Text Available The required water for greenhouses in Kishestan, Soume-e-Sara town, Guilan province, Iran, is mainly provided by underground resources that have inappropriate quality. One way to reduce the impact of salinity an plant growth is proper nutrition. This greenhouse research was conducted to evaluate the effect of water salinity and foliar spray of calcium (Ca and silicon (Si on growth and vase life of gerbera in a factorial experiment based on compeletly randomized design with two factors. The first factor was salinity of irrigation water at two levels (0 and 1.5 dS/m and the second factor was foliar spray at seven levels (without spray, twice Ca spray, four times Ca spray, two times Ca spray + once Si spray, twice Ca spray + twice Si spray, four times Ca spray + once Si spray, and four times Ca spray + twice Si spray, each with three replications. Results showed that four times Ca foliar spray led to an increase in stem hight, stem and neck diameter, postharvest life and Ca concentration of shoots. In all spray treatments, number of flowers in zero salinity was more than 1.5 dS/m treatments. In general, in case of using low-quality water (electrical conductivity of 1.5 dS/m, the effects of salinity on dry and fresh weights of gerbera plant and vase life of its flowers can be reduced by foliar application of Ca and Si. Since inappropriate water quality in Rasht Greenhouse Complex, Soume-e-Sara town, is one of the main problems of the farmers, especially in growing the ornamental plants, effects of salinity on plant growth could be alleviated with foliar spray of nutrients, especially Ca and Si. In this respect, four times spray of Ca and also twice spray of Ca + twice spray of Si are recommended.

  12. Evolution of trees and mycorrhizal fungi intensifies silicate mineral weathering

    OpenAIRE

    Quirk, J; D. J. Beerling; S. A. Banwart; Kakonyi, G.; Romero-Gonzalez, M. E.; Leake, J.R.

    2012-01-01

    Forested ecosystems diversified more than 350 Ma to become major engines of continental silicate weathering, regulating the Earth's atmospheric carbon dioxide concentration by driving calcium export into ocean carbonates. Our field experiments with mature trees demonstrate intensification of this weathering engine as tree lineages diversified in concert with their symbiotic mycorrhizal fungi. Preferential hyphal colonization of the calcium silicate-bearing rock, basalt, progressively increase...

  13. Scientific Opinion on the re-evaluation of sodium stearoyl-2-lactylate (E 481 and calcium stearoyl-2-lactylate (E 482 as food additives

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS

    2013-05-01

    Full Text Available Following a request by the European Commission, the Panel of Food Additives and Nutrient Sources added to Food (ANS was asked to deliver a scientific opinion on the safety of sodium stearoyl-2-lactylate (E 481, SSL and calcium stearoyl-2-lactylate (E 482, CSL when used as food additives. SSL and CSL are used as emulsifiers and stabilizers. An Acceptable Daily Intake (ADI of 20 mg/kg bw/day for SSL and CSL (either singly or in combination was established in 1974 by the Joint FAO/WHO Expert Committee on Food Additives (JECFA. The Scientific Committee on Food (SCF endorsed this ADI of 20 mg/kg bw/day in 1978. The biological fate of CSL is comparable in rodent and non-rodent species. The acute oral toxicity in rats is low. Subacute and subchronic oral toxicity studies with SSL and CSL in rats and dogs revealed a NOAEL of 5 % in the diet. Neither SSL and CSL nor their breakdown products stearic and lactic acid raise concern for genotoxicity. The NOAEL in a one-year oral toxicity study with SSL in rats was 2214 mg/kg bw/day for males and 2641 mg/kg bw/day for females. No data on reproductive toxicity and carcinogenicity were available. However, no reproductive or carcinogenic effects are expected since the products of hydrolysis, stearic and lactic acid are constituents of natural food and part of endogenous metabolism in mammals. The Panel concluded that based on the NOAEL of 2200 mg/kg bw/day derived from the one-year toxicity study in rats and an uncertainty factor of 100, an ADI of 22 mg/kg bw/day for sodium stearoyl-2-lactylate (E 481 and calcium stearoyl-2-lactylate (E 482 either singly or in combination can be established. The estimated exposure to SSL and CSL occurs mainly via the consumption of flavoured fermented milk products including heat treated products, bread and rolls and fine bakery wares and is below the ADI of 22 mg/kg bw/day for all the adult population including the elderly, but exceeds the ADI for other groups of the population

  14. Effect of Tartaric Acid on Hydration of a Sodium-Metasilicate-Activated Blend of Calcium Aluminate Cement and Fly Ash F

    Directory of Open Access Journals (Sweden)

    Tatiana Pyatina

    2016-05-01

    Full Text Available An alkali-activated blend of aluminum cement and class F fly ash is an attractive solution for geothermal wells where cement is exposed to significant thermal shocks and aggressive environments. Set-control additives enable the safe cement placement in a well but may compromise its mechanical properties. This work evaluates the effect of a tartaric-acid set retarder on phase composition, microstructure, and strength development of a sodium-metasilicate-activated calcium aluminate/fly ash class F blend after curing at 85 °C, 200 °C or 300 °C. The hardened materials were characterized with X-ray diffraction, thermogravimetric analysis, X-ray computed tomography, and combined scanning electron microscopy/energy-dispersive X-ray spectroscopy and tested for mechanical strength. With increasing temperature, a higher number of phase transitions in non-retarded specimens was found as a result of fast cement hydration. The differences in the phase compositions were also attributed to tartaric acid interactions with metal ions released by the blend in retarded samples. The retarded samples showed higher total porosity but reduced percentage of large pores (above 500 µm and greater compressive strength after 300 °C curing. Mechanical properties of the set cements were not compromised by the retarder.

  15. The clinical significance of testing serum calcium and sodium in children with febrile convulsion%热性惊厥患儿血清钙、钠检测及其临床意义

    Institute of Scientific and Technical Information of China (English)

    王刚

    2014-01-01

    To investigate the variation of Serum calcium and sodium concentration in children with febrile convulsion and its significance.Methods:Detect the serum calcium and sodium levels using automatic biochemical analyzer in 76 cases of children with febrile convulsion and 69 cases of the control group with fever,and compared it.Results:Serum calcium and sodium in febrile convulsion group were significantly lower than those of the control group(P<0.05).Conclusion:Children with febrile convulsion is in low calcium and low blood sodium.Reciprocal causation between febrile convulsion and low calcium and low sodium.For the treatment of febrile seizure,we should pay attention to correct the low calcium hyponatremia in addition to conventional anti convulsion and cooling,in order to prevent repeated attack of convulsion,and alleviate the damage on brain and other important organs.%目的:探讨热性惊厥患儿血清钙、钠浓度变化及其意义。方法:采用全自动生化测定仪检测76例热性惊厥患儿和对照组69例发热患儿的血清钙、钠水平,并进行比较分析。结果:热性惊厥组血清钙、钠明显低于对照组(P<0.05)。结论:热性惊厥患儿存在低血钙、低血钠。热性惊厥与低钙、低钠之间互为因果,针对热性惊厥治疗时除常规止惊、降温外应注意纠正低钙低钠血症,预防惊厥反复发作,减轻脑组织和其他重要脏器的损害。

  16. Scientific Opinion on the safety and efficacy of vitamin C (ascorbic acid and sodium calcium ascorbyl phosphate) as a feed additive for all animal species based on a dossier submitted by VITAC EEIG

    OpenAIRE

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP)

    2013-01-01

    Vitamin C (formerly known as antiscorbutic vitamin) is essential for primates, guinea pigs and fish. Vitamin C, in the form of ascorbic acid and sodium calcium ascorbyl phosphate, is safe for all animal species. Setting a maximum content in feed and water for drinking is not considered necessary. Data on the vitamin C consumption of consumers are based on the levels of vitamin C in foodstuffs, including food of animal origin, produced in accordance with current EU legislation on the supplemen...

  17. The effect of melt composition on the partitioning of oxidized sulfur between silicate melts and magmatic volatiles

    Science.gov (United States)

    Zajacz, Zoltán

    2015-06-01

    Experiments were conducted at 500 MPa and 1240 °C in a piston cylinder apparatus to assess the effect of melt composition on the melt/volatile partition coefficient of sulfur (DSmelt/volatile) , which was used as a measure of the silicate melt's capacity to dissolve oxidized sulfur species. Iron-free, three- and four-component silicate melts were equilibrated with H2O-S fluids with sulfur concentrations ⩽2 mol% at an oxygen fugacity imposed by the Re-ReO2 buffer (1.4 log units above the Ni-NiO buffer). At these conditions, SO2 (S4+) is predicted to be the dominant sulfur species in the volatile phase and sulfate (S6+) is the dominant sulfur species in the silicate melt. The values of DSmelt /volatile were calculated by mass balance. The results show that DSmelt /volatile values increase exponentially with decreasing the degree of polymerization of the silicate melt structure. For example, in calcium-aluminosilicate melts, DSmelt /volatile changes from 0.005 to 0.3 as the degree of melt polymerization changes from the equivalent of a rhyolite to the equivalent of a basalt. At a constant degree of melt polymerization, DSmelt /volatile in equilibrium with sodium-aluminosilicate (NAS) melts is more than an order of magnitude higher than in equilibrium with calcium-aluminosilicate (CAS) melts, and more than two orders of magnitude higher than in equilibrium with magnesium-aluminosilicate (MAS) melts. The value of DSmelt /volatile changes from 0.014 in MAS glasses to 3.4 in NAS glasses for the most depolymerized compositions in each series. Potassium has a similar effect on sulfate dissolution to that of Na. The variation of DSmelt /volatile in equilibrium with various calcium-sodium aluminosilicate (CNAS), magnesium-sodium aluminosilicate (MNAS) and magnesium-potassium aluminosilicate (MKAS) melts indicates that alkalis are only available for sulfate complexation when they are present in excess compared to the required amount to charge balance for the Si4+ to Al3

  18. Scientific Opinion on the safety and efficacy of vitamin C (ascorbic acid and sodium calcium ascorbyl phosphate as a feed additive for all animal species based on a dossier submitted by VITAC EEIG

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-02-01

    Full Text Available Vitamin C (formerly known as antiscorbutic vitamin is essential for primates, guinea pigs and fish. Vitamin C, in the form of ascorbic acid and sodium calcium ascorbyl phosphate, is safe for all animal species. Setting a maximum content in feed and water for drinking is not considered necessary. Data on the vitamin C consumption of consumers are based on the levels of vitamin C in foodstuffs, including food of animal origin, produced in accordance with current EU legislation on the supplementation of feed with vitamin C. The exposure is far below the guidance level. Any potential contribution of the use of vitamin C in feed is therefore already considered in the above data. Consequently, the use of vitamin C in animal nutrition is not of concern for consumer safety. In the absence of inhalation toxicity studies it would be prudent to assume that inhalation of dust from the additives presents a health hazard to workers and measures should be taken to minimise inhalation exposure. In the absence of data, ascorbic acid and sodium calcium ascorbyl phosphate should be considered as irritant to skin and eyes and as dermal sensitisers. The supplementation of feed with vitamin C does not pose a risk to the environment. Ascorbic acid and sodium calcium ascorbyl phosphate are regarded as effective sources of vitamin C when added to feed or water for drinking.

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

    Science.gov (United States)

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

    2015-04-01

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

  20. Silicate grout curtains behaviour for the protection of coastal aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Elektorowicz, M.; Chifrina, R.; Hesnawi, R. [Concordia Univ., Montreal, Quebec (Canada)

    1997-12-31

    Tests were performed to evaluate the behaviour of silicate grout with different reagents (ethylacetate - formamide SA and calcium chloride SC) in pure silica sand and natural soils from coastal areas containing organic matter, clayey soil and silica sand. The grouted specimens were tested with simulated fresh and salt water. The setting process during chemical grouting in the soil and sand was studied. The grouting of soil and sand with SA caused a transfer to the environment of some compounds: sodium formate, sodium acetate, ammonia and part of the initial ethylacetate and formamide. This process had a tendency to decrease for approximately 4 months. The stability of specimens was low. The grouting of soil and sand with SC caused no significant contamination of the environment. The increase of pH of environmental water was even less than with SA grouting. Also, the stability of specimens is higher in comparison with SA grouting. Salt water protected the specimens grouted with SA and SC from destruction and prevented contamination.

  1. Mechanical loss associated with silicate bonding of fused silica

    International Nuclear Information System (INIS)

    We report on mechanical loss associated with hydroxy-catalysis (or 'silicate') bonding between fused silica substrates in the presence of potassium hydroxide or sodium silicate. We measured the mechanical quality factor of three fused silica samples, each composed of two half-rods bonded together on their flat surfaces and compared them to that of an unbonded half-rod. The measurements show a significant reduction of quality factor due to mechanical loss associated with the silicate bonds. We calculate the loss factor of the bonded region φbond and estimate that the effect of silicate bonding on thermal noise in the Advanced LIGO interferometers will be small

  2. Behavior of calcium silicate in leaching process

    Institute of Scientific and Technical Information of China (English)

    刘桂华; 李小斌; 彭志宏; 周秋生

    2003-01-01

    Based on the thermodynamic calculation, the mole ratio of CaO to SiO2, temperature and A/S of bauxitehave a profound influence on the mole ratio of 2CaO @ SiO2 to CaO @ SiO2 in sinter. CaO @ SiO2 and β-2CaO @ SiO2appear stable in caustic solution but unstable in soda solution, and CaO @ SiO2 is more stable than β-2CaO @ SiO2 un-der the same leaching condition. Compared with the conventional sinter, the rate of alumina extraction of the newsinter is large and the secondary reaction is restricted in the leaching, which might be mainly due to the more contentof CaO @ SiO2 in sinter and better stability of CaO @ SiO2 in leaching.

  3. Calcium silicate hydrate: Crystallisation and alkali sorption

    International Nuclear Information System (INIS)

    Homogeneous single C-S-H gels has been prepared for the investigation of alkali binding potential and crystallisation. A distribution coefficient, Rd, was introduced to express the partition of alkali between solid and aqueous phases at 25 deg. C. Rd is independent of alkali hydroxide concentration and depends only on Ca:Si ratio over wide ranges of alkali concentration. The trend of numerical values of Rd indicates that alkali bonding into the solid improves as its Ca:Si ratio decreases. Reversibility is demonstrated, indicating a possibility of constant Rd value of the material. Al has been introduced to form C-A-S-H gels and their alkali sorption properties also determined. Al substituted into C-S-H markedly increases Rd, indicating enhancement of alkali binding. However, the dependence of Rd on alkali concentration is non-ideal with composition. A two-site model for bonding is presented. Crystallisation both under saturated steam and 1 bar vapour pressure has been investigated. It has been shown that heat treatment by saturated steam causes crystallisation of gels. The principal minerals obtained were (i) C-S-H gel and Ca(OH)2 at -55 deg. C, (ii) 1.1 nm tobermorite, jennite and afwillite at 85 -130 deg. C, and (iii) xonotlite, foshagite and hillebrandite at 150-180 deg. C. Properties of crystalline C-S-H were also reported for reversible phase transformation, pH conditioning ability, seeding effect and solubility. At 1 bar pressure, crystallisation is slower than in saturated steam due to lower water activity. Tobermorite-like nanodomains develop during reaction at low Ca/Si ratios. In some Ca-rich compositions, Ca(OH)2 is exsolved and occurs as nano-sized crystallites. (author)

  4. Scientific Opinion on the re-evaluation of propionic acid (E 280, sodium propionate (E 281, calcium propionate (E 282 and potassium propionate (E 283 as food additives

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Additives and Nutrient Sources added to food (ANS

    2014-07-01

    Full Text Available The EFSA ANS Panel provides a scientific opinion re-evaluating the safety of propionic acid (E 280, sodium propionate (E 281, calcium propionate (E 282 and potassium propionate (E 283 which are authorised as food additives in the EU and have been previously evaluated by the SCF and JECFA. JECFA allocated an ADI “not limited”. The SCF concluded that potassium propionate could be added to the list of preservatives and established an ADI ”not specified”. Propionates are naturally occurring substances in the normal diet. The Panel considered that forestomach hyperplasia reported in long-term studies in rodents is not a relevant endpoint for humans because humans lack this organ. Based on the reported presence of reversible diffuse epithelial hyperplasia in the oesophagus the LOAEL for a 90-day study in dogs was considered by the Panel to be 1 % propionic acid in the diet and the NOAEL to be 0.3 % propionic acid in the diet. The Panel considered that there is no concern with respect to genotoxicity and carcinogenicity. The Panel concluded that the present database did not allow allocation of an ADI for propionic acid - propionates. The overall mean and 95th percentile exposures to propionic acid - propionates resulting from their use as food additives (major contributor to exposure ranged from 0.7-21.1 and 3.6-40.8 mg/kg bw/day, respectively. The Panel noted that the concentration provoking site of contact effect in the 90-day study in dogs (1 % propionic acid in the diet is a factor of three higher than the concentration of propionic acid - propionates in food at the highest permitted level and concluded that for food as consumed, there would not be a safety concern from the maximum concentrations of propionic acid and its salts at their currently authorised uses and use levels as food additives.

  5. Silicate fertilizer and irrigation depth in corn production

    Directory of Open Access Journals (Sweden)

    Edvaldo Eloy Dantas Júnior

    2013-08-01

    Full Text Available Calcium-magnesium silicates improve the soil physicochemical properties and provide benefits to plant nutrition, since they are sources of silica, calcium and magnesium. The objective of this study was to evaluate the grain yield of irrigated corn fertilized with calcium-magnesium silicate. The experiment was carried out in a greenhouse in Campina Grande - PB, Brazil, using plastic pots containing 80 kg of soil. The treatments consisted of the combination of four irrigation depths, related to water replacement of 50, 75, 100 and 125% of the crop evapotranspiration, with fertilizer levels of 0, 82, 164 and 246 g of calcium-magnesium silicate, with three replications. The experimental design was in randomized blocks, with the irrigation depths distributed in bands while the silicon levels constituted the subplots. Corn yield was influenced by calcium-magnesium silicate and by irrigation depth, obtaining the greatest grain yield with the dose of 164 g pot-1 irrigated at the highest water level. The water-use efficiency of in corn production tended to decrease when the irrigation depth was increased. The best water-use efficiency was observed when the irrigation level was between 87 and 174 mm, and the dose of silicate was 164 g pot-1.

  6. Suprimento do silicato de cálcio e a eficiência nutricional de variedades de cafeeiro Effect of calcium silicate suplly and the nutritional efficiency of coffee cultivars

    Directory of Open Access Journals (Sweden)

    Adélia Aziz Alexandre Pozza

    2009-12-01

    Full Text Available Embora não seja considerado nutriente essencial às plantas, o Si é classificado como elemento benéfico ou útil, mas pode alterar a dinâmica nutricional das plantas. Objetivando comparar a eficiência nutricional de variedades de cafeeiro (Catuaí, Mundo Novo e Icatu em resposta à adubação silicatada, realizou-se um experimento em blocos casualizados, com as três variedades de mudas em tubetes combinadas com seis doses de CaSiO3 (T0 = 0, T1 = 0,063, T2 = 0,125, T3 = 0,25, T4 = 0,5 e T5 = 1,0 g dm-3 de substrato. A variedade Icatu teve a maior eficiência de absorção (EA de Cu, Zn, Fe e Si, maior eficiência de uso (EU de N, K, Ca, B e Mn, não diferindo da Mundo Novo com relação aos nutrientes N, Ca e Mn, e maior eficiência de translocação (ET de N, S, Zn e de Fe. A Catuaí teve maior EA de P, K, B e Mn, não diferindo da Mundo Novo com relação aos nutrientes P, K e Mn, maior EU para Mg, S, Cu, Zn, Fe e Si, provavelmente devido à melhor ET desses nutrientes, exceto para Fe e Si. A Mundo Novo foi mais eficiente na absorção de N, K, Ca, Mg, Mn e Si, teve maior EU de P e Mn e maior ET de K, Ca, B, Mn e Si.Silicon is classified as a beneficial nutrient and can improve the nutritional dynamics of plants, although it is not considered an essential nutrient for plants. In an experiment in a randomized block design, three coffee cultivars (Catuaí, Mundo Novo and Icatu were planted in plastic tubes, combined with six doses of calcium silicate (T0=0, T1=0.063, T2=0.125, T3=0.25, T4=0.5 and T5=1.0 g dm-3 substrate, to compare the nutritional efficiency of the cultivars in response to silicon fertilization. Cultivar Icatu showed the higher uptake efficiency (UE of Cu, Zn, Fe, and Si, and efficiency of use (EU of N, K, Ca, B, and Mn, but the later did not differ from Mundo Novo cultivar (N, Ca, and Mn. The efficiency of translocation (ET was higher for N, S, Zn, and Fe. For Catuaí the uptake efficiency of P, K, B, and Mn was higher

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

    OpenAIRE

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

    2013-01-01

    The effect of modified atmosphere packaging (MAP; 30% CO2+70% N2 or 100% N2) and an additive mixture (500 ppm rosemary extract, 3,000 ppm sodium acetate and 1,500 ppm calcium lactate) on the quality of pre-cooked hamburger patties during storage at 5°C for 14 d was evaluated. The addition of the additive mixture reduced aerobic and anaerobic bacteria counts in both 30% CO2-MAP (30% CO2+70% N2) and 100% N2-MAP (p

  8. Low-temperature fabrication of macroporous scaffolds through foaming and hydration of tricalcium silicate paste and their bioactivity

    OpenAIRE

    Huan, Z.; Chang, J.; Zhou, J.

    2009-01-01

    A low-temperature fabrication method for highly porous bioactive scaffolds was developed. The two-step method involved the foaming of tricalcium silicate cement paste and hydration to form calcium silicate hydrate and calcium hydroxide. Scaffolds with a combination of interconnected macro- and micro-sized pores were fabricated by making use of the decomposition of a hydrogen peroxide (H2O2) solution that acted as a foaming agent and through the hydration of tricalcium silicate cement. It was ...

  9. Nanostructured silicate polymer concrete

    Directory of Open Access Journals (Sweden)

    Figovskiy Oleg L'vovich

    2014-03-01

    Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

  10. 21 CFR 184.1763 - Sodium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... solution and also by reacting calcium hydroxide with sodium carbonate. (b) The ingredient meets the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium hydroxide. 184.1763 Section 184.1763 Food... Specific Substances Affirmed as GRAS § 184.1763 Sodium hydroxide. (a) Sodium hydroxide (NaOH, CAS Reg....

  11. Review of concrete performance at elevated temperature and hot sodium exposure applications in nuclear industry

    International Nuclear Information System (INIS)

    Highlights: ► Hot liquid sodium and concrete interactions in fast breeder reactors are reviewed. ► Thermal and sodium effects are discussed separately in this paper. ► Concrete experiences chemical and thermal instability due to hot sodium. ► Uncertainties still persist in assessing the basic phenomena during the exposure. ► Microstructural study is required to understand fundamental degradation mechanisms. -- Abstract: In the normal operating conditions of fast breeder reactors [FBRs], liquid sodium is used as heat transfer medium at the maximum temperature of 550 °C. Sodium leakage accidents pose various safety issues related to loss in structural integrity and performance characteristics of concrete structures. Thermo-chemical interactions of liquid sodium with concrete at 550 °C and above result in degradation of concrete in several ways. Concrete is a composite material and exhibits instability due to thermal and chemical loading of hot sodium. The increase in concrete temperature leads to a sequence of events – dehydration of cement paste above 100 °C, crack formation in the range of 400–1000 °C, decomposition of hydrated cement products like calcium hydroxide [Ca(OH)2] at 450 °C, mineralogical changes in aggregates above 500 °C, disintegration of calcium silicate hydrates [CSHs] above 600 °C and formation of glassy powder around 1200 °C. Thermo-chemical interaction of concrete with sodium consists of three phases, namely, initiation, propagation and termination. Initiation phase is accompanied with liberation of moisture from the interior of concrete and its subsequent reactions with sodium resulting in the formation of sodium hydroxide [NaOH], hydrogen gas [H2], sodium oxide [Na2O] and sodium hydride [NaH]. Propagation and termination phase are governed by total sodium leaked, temperature at the reaction interface and types of aggregate used. To protect the structural concrete from deterioration, generally a sacrificial layer of cement

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

    Science.gov (United States)

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

    2000-12-01

    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 4·2H 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.

  13. Method of chemical analysis of silicate rocks (1962)

    International Nuclear Information System (INIS)

    A rapid method of analysis for the physical and chemical determination of the major constituents of silicate rocks is described. Water losses at 100 deg. C and losses of volatile elements at 1000 deg. C are estimated after staying in oven for these temperatures, or by mean of a thermo-balance. The determination of silica is made by a double insolubilization with hydrochloric acid on attack solution with sodium carbonate; total iron and aluminium, both with calcium and magnesium, after ammoniacal precipitation of Fe and Al, are determined on the filtration product of silica by titrimetry-photometry of their complexes with EDTA. The alkalis Na and K by flame spectrophotometry, Mn by colorimetry of the permanganate, and Ti by mean of his complex with H2O2, are determined on fluosulfuric attack solution. Phosphorus is determined by his complex with 'molybdenum blue' on a fluoro-nitro-boric attack solution; iron is estimated by potentiometry, with the help of bichromate on hydrofluoric solution. (author)

  14. Calcium transport in turtle bladder

    International Nuclear Information System (INIS)

    Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa). Ouabain reversed JnetCa to an absorptive flux. Amiloride reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory. When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was ≅30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa

  15. The effect of sodium humate upon phosphorus nutrition of plants with variable doses of iron and calcium in tomato water cultures

    Directory of Open Access Journals (Sweden)

    M. J. Lisiak

    2015-05-01

    Full Text Available Studies were carried out on the effect of sodium humate upon content of P, Fe, Ca, and dry weight yield of tomato seedlings in water cultures. Nutrient solutions contained 10 times more or 10 times less P, Fe, and Ca than the control (nutrient solution according to Hampe. Sodium humate was effective only in relation to phosphorus at lowered amount of Fe, and supplied the plants with Fe when phosphorus content remained in excess. At lowered Ca content humate was not more effective in relation to phosphorus. Sodium humate protected the plants against inhibiting effects of excessive Ca content, and supplied them with phosphorus.

  16. Artrodese na coluna cervical utilizando SICAP como substituto de enxerto ósseo Artrodesis en la columna cervical utilizando SICAP como sustituto de injerto óseo Cervical spine fusion utilizing silicated calcium phosphate bone graft substitute (SICAP

    Directory of Open Access Journals (Sweden)

    Juliano Fratezi

    2011-01-01

    Tech EE.UU, Reino Unido es un injerto óseo compuesto de calcio-fosfato con una sustitución de silicato en la estructura química, con una estructura tridimensional que parece hueso natural. MÉTODOS: 19 pacientes fueron sometidos a fusión ósea cervical y analizados retrospectivamente. La evaluación radiográfica y la evaluación clínica fueron realizadas utilizandose el cuestionario Neck Disability Index y la escala análoga del dolor (VAS pre y postoperación. RESULTADOS: El período promedio de seguimiento postoperatorio fue de 14 meses ± 5 meses (7-30 meses. Once pacientes fueron sometidos a fusión vía anterior; 5 pacientes vía posterior y 3 pacientes vía anterior y posterior. La revisión radiográfica mostró 19/19 (100% de fusión ósea, ningún caso presentó subsidencia, rotura o soltura de material de implante o movimiento en los niveles fusionados. Ningún ejemplo de osificación heterotópica o de crecimiento óseo intracanal fue observado. Clínicamente, el promedio de las puntuaciones del Neck Disability disminuyeron 13,3 puntos (promedio preop. de 34,5, postop. de 21,2, mejora de 39%, el promedio de VAS para dolor cervical disminuyó 2 puntos (2,7 preop. para 0,7 postop.; mejora de 74,1%. No fueron observadas complicaciones como infección, osteólisis o edema excesivo de las partes blandas. CONCLUSIÓN: Los resultados preliminares obtenidos en esta serie feuron estimulantes con el uso de SICaP como injerto óseo, con sólida fusión ósea obtenida en todos los casos y sin formación de osificación heterotópica o crecimiento de hueso intracanal. SIcaP demuestra ser un sustituto confiable para el injerto óseo autólogo en la columna cervical.OBJECTIVE: Bone graft substitutes have been developed to obviate the need for autograft from the iliac crest and its resultant complications. SiCaP (Actifuse, ApaTech US, UK is a calcium phosphate bone graft substitute with selective controlled silicate substitution in a patented 3-dimensional structure

  17. FFTF vertical sodium storage tank preliminary thermal analysis

    International Nuclear Information System (INIS)

    In the FFTF Shutdown Program, sodium from the primary and secondary heat transport loops, Interim Decay Storage (IDS), and Fuel Storage Facility (FSF) will be transferred to four large storage tanks for temporary storage. Three of the storage tanks will be cylindrical vertical tanks having a diameter of 28 feet, height of 22 feet and fabricated from carbon steel. The fourth tank is a horizontal cylindrical tank but is not the subject of this report. The storage tanks will be located near the FFTF in the 400 Area and rest on a steel-lined concrete slab in an enclosed building. The purpose of this work is to document the thermal analyses that were performed to ensure that the vertical FFTF sodium storage tank design is feasible from a thermal standpoint. The key criterion for this analysis is the time to heat up the storage tank containing frozen sodium at ambient temperature to 400 F. Normal operating conditions include an ambient temperature range of 32 F to 120 F. A key parameter in the evaluation of the sodium storage tank is the type of insulation. The baseline case assumed six inches of calcium silicate insulation. An alternate case assumed refractory fiber (Cerablanket) insulation also with a thickness of six inches. Both cases assumed a total electrical trace heat load of 60 kW, with 24 kW evenly distributed on the bottom head and 36 kW evenly distributed on the tank side wall

  18. Effect of silicate fertilization on soil and on palisade grass plants under grazing intensities

    OpenAIRE

    Pedro Henrique de Cerqueira Luz; Letícia de Abreu Faria; Felipe Barros Macedo; Valdo Rodrigues Herling; Antonio Batista Sanches; Rosane Cláudia Rodrigues

    2011-01-01

    Application of calcium silicate (SiCa) as soil acidity corrective was evaluated in a Rhodic Hapludox soil with palisade grass conducted under pasture rotation system with different grazing intensities. Experimental design was complete randomized blocks with four grazing intensities - grazing intensities were imposed by forage supply (50, 100, 150 and 200 kg t-1 of DM per LW) - in experimental plots with four replicates and, in the subplots, with seven doses of calcium silicate combined with l...

  19. Effect of calcium and magnesium silicate on the growth of the castor oil plant subjected to salinity levels Efeito de silicato de cálcio e magnésio sobre o crescimento de plantas de mamoneira submetidas a níveis de salinidade

    Directory of Open Access Journals (Sweden)

    José Félix Brito Neto

    2012-12-01

    Full Text Available Salt stress decreases the osmotic potential of soil solution causing water stress, causing toxic effects in the plants resulting in injuries on the metabolism and nutritional disorders, thus compromising the plant growth, resulting in lower production. The calcium silicate and magnesium can perform the same function as limestone, besides providing silicon to plants, may also contribute to the resistance of plants to salt stress. Thus, the objective of this study was to evaluate the effect of calcium and magnesium silicate on the growth of the castor oil plant BRS Energia cultivated under saline conditions. This study evaluated plant height, stem diameter, number of leaves, leaf area, dry weight of shoot and root, and soil chemical characteristics. There was no interaction between factors of salinity level and of silicate level regarding the evaluated variables. There was a direct relationship between salinity levels and plant growth in height and stem diameter. The K concentration in soil were affected by salinity levels. O estresse salino diminui o potencial osmótico da solução do solo causando estresse hídrico, provocando efeitos tóxicos nas plantas que resultam em injúrias no metabolismo e desordens nutricionais, comprometendo assim o crescimento das plantas, resultando em menor produção. O silicato de cálcio e magnésio pode desempenhar a mesma função do calcário, além de fornecer silício para as plantas, podendo ainda, contribuir para a resistência de plantas ao estresse salino. Nesse sentido, objetivou-se com esse trabalho avaliar o efeito do silicato de cálcio e magnésio no crescimento da mamoneira BRS Energia cultivada sob condições salinas. Avaliou-se a altura da planta, diâmetro do caule, número de folhas, área foliar, massa seca da parte aérea e da raiz e as características químicas do solo. Não houve interação entre os fatores níveis de salinidade e silicato sobre as variáveis analisadas. Houve rela

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  1. Influence of portland cement replacement in high calcium fly ash geopolymer paste

    Directory of Open Access Journals (Sweden)

    Tanakorn Phoo-ngernkham

    2014-03-01

    Full Text Available This article presents the influence of ordinary Portland cement (OPC replacement in high calcium fly ash (FA geopolymer paste. FA was used to replace OPC at the rate of 5, 10 and 15% by mass of binder. Sodium silicate (Na2SiO3 and 10 molar sodium hydroxide (NaOH solutions were used as the alkaline solution in the reaction. The Na2SiO3/NaOH ratio of 2.0 and the liquid/binder (L/B ratio of 0.60 were used in all mixtures. The results of increase OPC replacement, the setting time and compressive strain capacity decreased while the compressive strength and modulus of elasticity increased. The compressive strength and modulus of elasticity at 28 days of geopolymer pastes with 15% OPC replacement were 36.7 MPa and 13,300 MPa, respectively.

  2. 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

    Science.gov (United States)

    Craner, Matthew J.; Hains, Bryan C.; Lo, Albert C.; Black, Joel A.; Waxman, Stephen G.

    2004-01-01

    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…

  3. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Science.gov (United States)

    2013-03-06

    ... AGENCY Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl Sodium... the registration review of cyromazine, silica silicates (silica dioxide and silica gel), glufosinate..., consistent with the notice published in the Federal Register of August 17, 2012, (77 FR 49792)...

  4. Silicate Urolithiasis during Long-Term Treatment with Zonisamide

    Directory of Open Access Journals (Sweden)

    Satoru Taguchi

    2013-01-01

    Full Text Available Silicate urinary calculi are rare in humans, with an incidence of 0.2% of all urinary calculi. Most cases were related to excess ingestion of silicate, typically by taking magnesium trisilicate as an antacid for peptic ulcers over a long period of time; however, there also existed unrelated cases, whose mechanism of development remains unclear. On the other hand, zonisamide, a newer antiepileptic drug, is one of the important causing agents of iatrogenic urinary stones in patients with epilepsy. The supposed mechanism is that zonisamide induces urine alkalinization and then promotes crystallization of urine components such as calcium phosphate by inhibition of carbonate dehydratase in renal tubular epithelial cells. Here, we report a case of silicate urolithiasis during long-term treatment with zonisamide without magnesium trisilicate intake and discuss the etiology of the disease by examining the silicate concentration in his urine.

  5. The effect of a high-protein, high-sodium diet on calcium and bone metabolism in postmenopausal women stratified by hormone replacement therapy use

    DEFF Research Database (Denmark)

    Harrington, M.; Bennett, T.; Jakobsen, Jette; Ovesen, L.; Brot, C.; Flynn, A.; Cashman, K. D.

    2004-01-01

    The objective of this study was to investigate the influence of a high-sodium, high-protein diet on bone metabolism in postmenopausal women ( aged 49 - 60 y) stratified by hormone replacement therapy (HRT) use. In a crossover trial, 18 women (n = 8 HRT users (+HRT) and n = 10 nonusers (-HRT)) were...

  6. Prostaglandin E2 release from dermis regulates sodium permeability of frog skin epithelium

    DEFF Research Database (Denmark)

    Rytved, Klaus A.; Brodin, Birger; Nielsen, Robert

    1995-01-01

    Arachidonic acid, cAMP, epithelium, frog skin, intracellular calcium, prostaglandin E*U2, sodium transport, tight epithelium.......Arachidonic acid, cAMP, epithelium, frog skin, intracellular calcium, prostaglandin E*U2, sodium transport, tight epithelium....

  7. Electric field-induced softening of alkali silicate glasses

    International Nuclear Information System (INIS)

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown

  8. Electric field-induced softening of alkali silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    McLaren, C.; Heffner, W.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Tessarollo, R.; Raj, R. [Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)

    2015-11-02

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  9. Influence of sodium, calcium, magnesium, and ammonium in the sorption of cadmium in a zeolite rock; Influencia del sodio, calcio, magnesio y amonio en la sorcion de cadmio en una roca zeolitica

    Energy Technology Data Exchange (ETDEWEB)

    Teutli S, E.A

    2007-07-01

    The cadmium is one of the more toxic heavy metals and the water pollution by this metal, is originated by industries whose turn is the production of batteries, electroplating processes, the production of pigments and in the refinement process of others metals. The objective of this work was to evaluate the ion exchange of cadmium using natural zeolite, obtained from the Arroyo zone, La Haciendita Municipality, in the State of Chihuahua. The parameters considered in this investigation were: the sorption time, the pH, the initial concentration of cadmium and the influence of sodium, calcium, magnesium and ammonium on the sorption of cadmium in the natural zeolite. Also, the theoretical pattern for kinetics and isotherm that better it is adjusted to those experimental results it was determined. The experimentation results allowed to establish the following conclusions: the sorption of the cadmium doesn't depend on the pH in an interval between 4 and 6; the pattern that better it describes the kinetics it is that of Pseudo-second order of Ho and Mc Kay; the Langmuir-Freundlich pattern is the one that better it describes the sorption isotherm and the calcium is the component that interferes in an important manner in the sorption of cadmium. The carried out investigation contributes to the definition of some of the parameters that should be considered in the development of ion exchangers for the cadmium removal. (Author)

  10. Study of thermal effects of silicate-containing hydroxyapatites

    Science.gov (United States)

    Golovanova, O. A.; Zaits, A. V.; Berdinskaya, N. V.; Mylnikova, T. S.

    2016-02-01

    The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 0C that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state.

  11. Removal of Co (Ⅱ)and Radioactive Transition Metal Ions by Adsorption on Fly Ash-Derived Mesoporous Calcium-Silicate Material%粉煤灰衍生介孔硅钙材料吸附去除Co(Ⅱ)及放射性过渡金属离子性能研究

    Institute of Scientific and Technical Information of China (English)

    雷雪飞; 祁光霞; 孙应龙; 李磊; 袁超; 王毅; 孙俊民

    2014-01-01

    To meet the needs of treatment of waste water containing low-level radioactive transition metal ions,using Co (Ⅱ)as a representative,the sorption ability of Co (Ⅱ)on calcium-silicate material,which is produced at the pre-desilication stage during the alumina extraction from the high-alumina fly ash by pre-desilication-soda-lime sintering technique,was studied.The results indicate that the calcium-silicate material,with hydration calcium silicate (C—S—H(Ⅰ))as the main mineral,is one of those mesoporous materials with high specific surface area(733 m2/g)and developed void space structure.The material also has good acid and alkali buffer performance(pH=2-10)and cation exchange capacity(Ca2+/H+).The adsorption capacity can reach 209-296 mg/g in the temperature range of 35-60 ℃for Co(Ⅱ).The adsorption process is endothermic and consistent with Langmuir monolayer chemical adsorption.The adsorption equilibrium can be reached quickly within 3 h.Our results show that the main adsorption mechanism is most ion exchange(84.5%).Moreover, the adsorption results for nuclear power plant overhaul wastewater show that more than 98.6% of the radioactive cobalt as well as other radioactive transition metal ions are removed.Speaking from the perspective of practical application,the mesoporous calcium-silicate material not only has high compatibility with cement which is good to the radionu-clide stabilization,but also can replace part of cement to achieve the reduction of the radioac-tive solidification blocks.Because of the above mentioned environmental and economic bene-fits,the mesoporous calcium-silicate material evidently has potential application in radioac-tive transition nuclide removal of wastewater.%针对含低水平放射性过渡金属离子废水的处理需求,本工作以 Co(Ⅱ)为代表,研究了粉煤灰衍生介孔硅钙材料对Co(Ⅱ)的吸附去除性能。研究结果表明,高铝粉煤灰“预脱硅-碱石灰烧结提铝”工艺在预脱硅阶

  12. Sodium Azide

    Science.gov (United States)

    ... Matters What's New A - Z Index Facts About Sodium Azide What sodium azide is Sodium azide is a rapidly acting, ... give people sufficient warning of the danger. Where sodium azide is found and how it is used ...

  13. THE ALUMINA-SILICATES IN STABILIZATION PROCESSES IN FLUIDIZED-BED ASH

    Directory of Open Access Journals (Sweden)

    IVANA PERNA

    2011-03-01

    Full Text Available Presented study of coal fluidized-bed ash solidification was accompanied with specific studies of alumino-silicates residues in ashes. The specific technology of fluid coal burning and its relatively low temperature combustion combines coal burning and decomposition of calcium carbonate added to the fluid layer in the main endeavor to capture all sulfur oxides. The burning temperature seems be decisive to the behavior of clayed residues and calcium carbonate decomposition in connection for the future solidification of fluidized bed ash. The calcareous substances in combination with alumino-silicate residues form solid bodies where silicates play decisive role of long-term stability and insolubility of obtained solids. The position of aluminum ions in clayed residues of burned coal were studied by MAS-NMR with attention on aluminum ion coordination to oxygen and formation of roentgen amorphous phase of poly-condensed calcium alumina-silicate.

  14. Hyperosmolar sodium chloride is toxic to cultured neurons and causes reduction of glucose metabolism and ATP levels, an increase in glutamate uptake, and a reduction in cytosolic calcium.

    Science.gov (United States)

    Morland, Cecilie; Pettersen, Mi Nguyen; Hassel, Bjørnar

    2016-05-01

    Elevation of serum sodium, hypernatremia, which may occur during dehydration or treatment with sodium chloride, may cause brain dysfunction and damage, but toxic mechanisms are poorly understood. We found that exposure to excess NaCl, 10-100mmol/L, for 20h caused cell death in cultured cerebellar granule cells (neurons). Toxicity was due to Na(+), since substituting excess Na(+) with choline reduced cell death to control levels, whereas gluconate instead of excess Cl(-) did not. Prior to cell death from hyperosmolar NaCl, glucose consumption and lactate formation were reduced, and intracellular aspartate levels were elevated, consistent with reduced glycolysis or glucose uptake. Concomitantly, the level of ATP became reduced. Pyruvate, 10mmol/L, reduced NaCl-induced cell death. The extracellular levels of glutamate, taurine, and GABA were concentration-dependently reduced by excess NaCl; high-affinity glutamate uptake increased. High extracellular [Na(+)] caused reduction in intracellular free [Ca(2+)], but a similar effect was seen with mannitol, which was not neurotoxic. We suggest that inhibition of glucose metabolism with ensuing loss of ATP is a neurotoxic mechanism of hyperosmolar sodium, whereas increased uptake of extracellular neuroactive amino acids and reduced intracellular [Ca(2+)] may, if they occur in vivo, contribute to the cerebral dysfunction and delirium described in hypernatremia. PMID:26994581

  15. Efeito do silicato de cálcio e da autoclavagem na supressividade e na conducividade de dois solos à Rhizoctonia solani Influence of calcium silicate and sterilization on the natural suppressiveness and on the conduciveness of two soils to Rhizoctonia solani

    Directory of Open Access Journals (Sweden)

    Fabrício de Ávila Rodrigues

    1999-08-01

    Full Text Available Objetivou-se verificar o efeito da aplicação de silicato de cálcio e da esterilização na supressividade natural de um Latossolo Vermelho-Escuro (LEa álico textura muito argilosa e na conducividade natural de uma Terra Roxa Estruturada eutrófica (TRe ao fungo Rhizoctonia solani, em condições de casa de vegetação. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 2 x 3 x 2. Os fatores foram: duas classes de solo (LEa e TRe - 0-20 cm; três tratamentos (esterilização ou não por autoclavagem, aplicação de silicato e testemunha e infestação ou não com R. solani, com três repetições e 16 plântulas de feijoeiro por parcela. A aplicação de silicato foi feita incorporando 0,63 g do produto em 1 kg de cada material de solo, seguido de incubação por 30 dias. Para promover a infestação artificial, foram colocados 800 mg de inóculo em 1 kg de cada material de solo. O silicato de cálcio aumentou os teores de Ca trocável e a soma de bases nos dois solos. Um decréscimo na saturação por Al de 70 para 19% e um aumento na saturação por bases de 9 para 21% alteraram significativamente a supressividade natural do LEa à R. solani. Com relação à TRe, a aplicação de silicato não teve nenhum efeito na sua conducividade, dado ao seu natural caráter eutrófico, o qual já é favorável ao desenvolvimento deste fungo. A esterilização não influiu no desenvolvimento de R. solani, o que sugere que os fatores abióticos foram os responsáveis pela supressividade ou conducividade desses solos.The effect of calcium silicate slag and soil sterilization on the natural suppressiveness of a Typic Acrustox (clay Dark Red Latosol -- LEa and the natural conduciveness of an Oxic Haplustoll (TRe to Rhizoctonia solani were studied under greenhouse conditions. The experimental design was a three-replicate completely randomized one, with 2 x 3 x 2 factorial combination of the following treatments: two soil kinds (LEa and

  16. Method of chemical analysis of silicate rocks (1962); Methode d'analyse chimique des roches silicatees (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Pouget, R. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1962-07-01

    A rapid method of analysis for the physical and chemical determination of the major constituents of silicate rocks is described. Water losses at 100 deg. C and losses of volatile elements at 1000 deg. C are estimated after staying in oven for these temperatures, or by mean of a thermo-balance. The determination of silica is made by a double insolubilization with hydrochloric acid on attack solution with sodium carbonate; total iron and aluminium, both with calcium and magnesium, after ammoniacal precipitation of Fe and Al, are determined on the filtration product of silica by titrimetry-photometry of their complexes with EDTA. The alkalis Na and K by flame spectrophotometry, Mn by colorimetry of the permanganate, and Ti by mean of his complex with H{sub 2}O{sub 2}, are determined on fluosulfuric attack solution. Phosphorus is determined by his complex with 'molybdenum blue' on a fluoro-nitro-boric attack solution; iron is estimated by potentiometry, with the help of bichromate on hydrofluoric solution. (author) [French] Une methode d'analyse rapide est decrite pour la determination physico-chimique des constituants principaux des roches silicatees. Les pertes en eau a 100 deg. C et en matieres volatiles a 1000 deg. C sont evaluees apres passage au four a ces temperatures, ou a l'aide d'une thermobalance. La determination de la silice se fait par double insolubilisation a l'acide chlorhydrique, sur une attaque au carbonate de sodium; le fer total et l'aluminium ainsi que le calcium et le magnesium, apres precipitation a l'ammoniaque des deux premiers metaux, sont determines sur le filtrat de la silice par titrimetrie-photometrie de leurs complexes avec l'E.D.T.A. Les alcalins sodium et potassium par spectrophotometrie de flamme, le manganese par colorimetrie du permanganate, le titane a l'aide de son complexe avec l'eau oxygenee, sont determines sur une attaque fluosulfurique. Le phosphore est determine par son

  17. Durability Study on High Calcium Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Ganesan Lavanya

    2015-01-01

    Full Text Available This study presents an investigation into the durability of geopolymer concrete prepared using high calcium fly ash along with alkaline activators when exposed to 2% solution of sulfuric acid and 5% magnesium sulphate for up to 45 days. The durability was also assessed by measuring water absorption and sorptivity. Ordinary Portland cement concrete was also prepared as control concrete. The grades chosen for the investigation were M20, M40, and M60. The alkaline solution used for present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 2.50. The molarity of sodium hydroxide was fixed as 12. The test specimens were 150×150×150 mm cubes, 100×200 mm cylinders, and 100×50 mm discs cured at ambient temperature. Surface deterioration, density, and strength over a period of 14, 28, and 45 days were observed. The results of geopolymer and ordinary Portland cement concrete were compared and discussed. After 45 days of exposure to the magnesium sulfate solution, the reduction in strength was up to 12% for geopolymer concrete and up to 25% for ordinary Portland cement concrete. After the same period of exposure to the sulphuric acid solution, the compressive strength decrease was up to 20% for geopolymer concrete and up to 28% for ordinary Portland cement concrete.

  18. EXAFS studies of silicate glasses containing uranium

    International Nuclear Information System (INIS)

    Sodium silicate glasses containing hexavalent uranium ions have been studied using the EXAFS technique. The U6+ ions appear in the uranyl configuration with two oxygen atoms at 1.85 A and four to five at 2.2-2.3 A. In the glasses (0.25Na2O.0.75SiO2)sub(1-x)(UO3)sub(x) with x = 0.02 to x = 0.1, planar (or nearly planar) uranium containing clusters, with U-U distances of 3.3 A, are observed. A layered model is proposed to describe these glasses. (Auth.)

  19. Adsorption of Free Fatty Acid from Crude Palm Oil on Magnesium Silicate Derived from Rice Husk

    OpenAIRE

    Pornsawan Assawasaengrat; Prakob Kitchaiya; Weerawat Clowutimon

    2011-01-01

    Magnesium silicate with various silica and magnesium oxide ratios (SiO2/MgO ratios) was used as the adsorbent for a study of adsorption of free fatty acid (FFA) in crude palm oil (CPO). Magnesium silicate was prepared from magnesium nitrate or magnesium sulfate solution precipitated with a solution of sodium silicate derived from rice husk. SiO2/MgO ratios of the magnesium silicate synthesized from magnesium nitrate and magnesium sulfate were 3.93, 3.75, 2.74, 2.40, 1.99 and 3.96, 3.61, 3.51,...

  20. Tin-Containing Silicates

    DEFF Research Database (Denmark)

    Tolborg, Søren; Meier, Sebastian; Sádaba, I.;

    2016-01-01

    Inorganic glycolytic systems, capable of transforming glucose through a cascade of catalytic steps, can lead to efficient chemical processes utilising carbohydrates as feedstock. Tin-containing silicates, such as Sn-Beta, are showing potential for the production of lactates from sugars through a ...