Magnesite Solubility at 800 ºC, 10 kbar, in H2O-CO2± NaCl solutions: implications for carbon transport in the mantle

NASA Astrophysics Data System (ADS)

Fineman, D.; Manning, C. E.

2017-12-01

Magnesite (MgCO3) is an important carbon reservoir in the upper mantle. It can be a product of interaction with mantle fluids, but its solubility has not been determined at high P and T. We measured magnesite solubility at 800 ºC, 10 kbar, in H2O-CO2± NaCl solutions. The NaCl mole fraction (XNaCl) ranged from 0 to 0.4. XCO2 = 0.05 was fixed by addition of hydrous oxalic acid and low fH2 generated by hematite or Mn oxide sealed in inner Pt capsules, added along with a crimped Pt capsule containing pure natural magnesite crystals to a larger Pt capsule containing H2O-CO2± NaCl fluid. Solubility was determined after quenching by the weight loss of the capsule containing magnesite. Magnesite solubility in pure water is 0.02 molal, nearly the same as calcite, 0.025 molal. Solubility rises to 0.37 molal with addition of NaCl to XNaCl =0.3. This value is 1/3 that of calcite at the same XNaCl. Graphite precipitated in experiments at XNaCl > 0.3 and resulted in inconsistent solubility measurements. There are two probable causes: (1) reduction of H2O activity and increase in CO2 activity via NaCl addition, or (2) exhaustion of the fO2 buffer. The experiments demonstrate that transport of Mg+2 and carbonate are substantially increased by saline solutions in the mantle.

Specific ion-protein interactions dictate solubility behavior of a monoclonal antibody at low salt concentrations.

PubMed

Zhang, Le; Zhang, Jifeng

2012-09-04

The perturbation of salt ions on the solubility of a monoclonal antibody was systematically studied at various pHs in Na(2)SO(4), NaNO(3), NaCl, NaF, MgSO(4), Mg(NO(3))(2) and MgCl(2) solutions below 350 mM. At pH 7.1, close to the pI, all of the salts increased the solubility of the antibody, following the order of SO(4)(2-) > NO(3)(-) > Cl(-) > F(-) for anions and Mg(2+) > Na(+) for cations. At pH 5.3 where the antibody had a net positive charge, the anions initially followed the order of SO(4)(2-) > NO(3)(-) > Cl(-) > F(-) for effectiveness in reducing the solubility and then switched to increasing the solubility retaining the same order. Furthermore, the antibody was more soluble in the Mg(2+) salt solutions than in the corresponding Na(+) salt solutions with the same anion. At pH 9.0 where the antibody had a net negative charge, an initial decrease in the protein solubility was observed in the solutions of the Mg(2+) salts and NaF, but not in the rest of the Na(+) salt solutions. Then, the solubility of the antibody was increased by the anions in the order of SO(4)(2-) > NO(3)(-) > Cl(-) > F(-). The above complex behavior is explained based on the ability of both cation and anion from a salt to modulate protein-protein interactions through their specific binding to the protein surface.

A Pyrophosphate Based Energy Generating Module

DTIC Science & Technology

2008-12-01

OMB control number. 1. REPORT DATE DEC 2008 2 . REPORT TYPE N/A 3 . DATES COVERED - 4. TITLE AND SUBTITLE A Pyrophosphate Based Energy...for each substrate (PPi, PEP, and AMP) using double reciprocal Lineweaver-Burk plots of saturation data. 10| 2 10| 3 10|4 10|5 10|6 10|7 10-11 10- 10...Partitioning 1 2 3 4 Bilayer - + + + α-Hemolysin - - + + Upper Reservoir +PPi, +PEP +PPi, +PEP +PPi, +PEP +PPi, +PEP, +Luc Lower Reservoir +AMP

The route of non-enzymic and enzymic breakdown of 5-phosphoribosyl 1-pyrophosphate to ribose 1-phosphate.

PubMed Central

Trembacz, H; Jezewska, M M

1990-01-01

Spontaneous decomposition of 5-phosphoribosyl 1-pyrophosphate at pH 5.5 was established to occur as follows: 5-Phosphoribosyl 1-pyrophosphate----5-phosphoribosyl 1,2-(cyclic)phosphate----ribose 1-phosphate----ribose Enzymic degradation of 5-phosphoribosyl 1-pyrophosphate by alkaline phosphatase from calf intestine and by acid phosphatases from potato and Aspergillus niger was found to proceed according to this pathway within the pH range 2.5-7.4 with accumulation of ribose 1-phosphate. In the case of alkaline phosphatase, Mg2+ ions inhibit the pyrophosphorolysis of 5-phosphoribosyl 1-pyrophosphate and stimulate the hydrolysis of ribose 1-phosphate. PMID:1700897

A mixed iron-manganese based pyrophosphate cathode, Na2Fe0.5Mn0.5P2O7, for rechargeable sodium ion batteries.

PubMed

Shakoor, Rana A; Park, Chan Sun; Raja, Arsalan A; Shin, Jaeho; Kahraman, Ramazan

2016-02-07

The development of secondary batteries based on abundant and cheap elements is vital. Among various alternatives to conventional lithium-ion batteries, sodium-ion batteries (SIBs) are promising due to the abundant resources and low cost of sodium. While there are many challenges associated with the SIB system, cathode is an important factor in determining the electrochemical performance of this battery system. Accordingly, ongoing research in the field of SIBs is inclined towards the development of safe, cost effective cathode materials having improved performance. In particular, pyrophosphate cathodes have recently demonstrated decent electrochemical performance and thermal stability. Herein, we report the synthesis, electrochemical properties, and thermal behavior of a novel Na2Fe0.5Mn0.5P2O7 cathode for SIBs. The material was synthesized through a solid state process. The structural analysis reveals that the mixed substitution of manganese and iron has resulted in a triclinic crystal structure (P1[combining macron] space group). Galvanostatic charge/discharge measurements indicate that Na2Fe0.5Mn0.5P2O7 is electrochemically active with a reversible capacity of ∼80 mA h g(-1) at a C/20 rate with an average redox potential of 3.2 V. (vs. Na/Na(+)). It is noticed that 84% of initial capacity is preserved over 90 cycles showing promising cyclability. It is also noticed that the rate capability of Na2Fe0.5Mn0.5P2O7 is better than Na2MnP2O7. Ex situ and CV analyses indicate that Na2Fe0.5Mn0.5P2O7 undergoes a single phase reaction rather than a biphasic reaction due to different Na coordination environment and different Na site occupancy when compared to other pyrophosphate materials (Na2FeP2O7 and Na2MnP2O7). Thermogravimetric analysis (25-550 °C) confirms good thermal stability of Na2Fe0.5Mn0.5P2O7 with only 2% weight loss. Owing to promising electrochemical properties and decent thermal stability, Na2Fe0.5Mn0.5P2O7, can be an attractive cathode for SIBs.

Solubility of NaCl in water by molecular simulation revisited.

PubMed

Aragones, J L; Sanz, E; Vega, C

2012-06-28

In this paper, the solubility of NaCl in water is evaluated by using computer simulations for three different force fields. The condition of chemical equilibrium (i.e., equal chemical potential of the salt in the solid and in the solution) is obtained at room temperature and pressure to determine the solubility of the salt. We used the same methodology that was described in our previous work [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] although several modifications were introduced to improve the accuracy of the calculations. It is found that the predictions of the solubility are quite sensitive to the details of the force field used. Certain force fields underestimate the experimental solubility of NaCl in water by a factor of four, whereas the predictions of other force fields are within 20% of the experimental value. Direct coexistence molecular dynamic simulations were also performed to determine the solubility of the salt. Reasonable agreement was found between the solubility obtained from free energy calculations and that obtained from direct coexistence simulations. This work shows that the evaluation of the solubility of salts in water can now be performed in computer simulations. The solubility depends on the ion-ion, ion-water, and water-water interactions. For this reason, the prediction of the solubility can be quite useful in future work to develop force fields for ions in water.

21 CFR 182.8223 - Calcium pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium pyrophosphate. 182.8223 Section 182.8223... FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use. This substance is generally recognized...

21 CFR 182.8223 - Calcium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pyrophosphate. 182.8223 Section 182.8223... FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use. This substance is generally recognized...

21 CFR 582.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium pyrophosphate. 582.6787 Section 582.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Condition of use. This substance is...

21 CFR 182.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium pyrophosphate. 182.6787 Section 182.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Conditions of use. This substance is...

21 CFR 582.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium pyrophosphate. 582.6787 Section 582.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Condition of use. This substance is...

21 CFR 182.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium pyrophosphate. 182.6787 Section 182.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Conditions of use. This substance is...

21 CFR 182.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium pyrophosphate. 182.6787 Section 182.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Conditions of use. This substance is...

21 CFR 182.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium pyrophosphate. 182.6787 Section 182.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Conditions of use. This substance is...

21 CFR 582.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium pyrophosphate. 582.6787 Section 582.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Condition of use. This substance is...

21 CFR 582.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium pyrophosphate. 582.6787 Section 582.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Condition of use. This substance is...

21 CFR 582.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium pyrophosphate. 582.6787 Section 582.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium pyrophosphate. (a) Product. Sodium pyrophosphate. (b) Condition of use. This substance is...

Treatment with pyrophosphate inhibits uremic vascular calcification

PubMed Central

O’Neill, W. Charles; Lomashvili, Koba A.; Malluche, Hartmut H.; Faugere, Marie-Claude; Riser, Bruce L.

2011-01-01

Pyrophosphate, which may be deficient in advanced renal failure, is a potent inhibitor of vascular calcification. To explore its use as a potential therapeutic, we injected exogenous pyrophosphate subcutaneously or intraperitoneally in normal rats and found that their plasma pyrophosphate concentrations peaked within 15 min. There was a single exponential decay with a half-life of 33 min. The kinetics were indistinguishable between the two routes of administration or in anephric rats. The effect of daily intraperitoneal pyrophosphate injections on uremic vascular calcification was then tested in rats fed a high-phosphate diet containing adenine for 28 days to induce uremia. Although the incidence of aortic calcification varied and was not altered by pyrophosphate, the calcium content of calcified aortas was significantly reduced by 70%. Studies were repeated in uremic rats given calcitriol to produce more consistent aortic calcification and treated with sodium pyrophosphate delivered intraperitoneally in a larger volume of glucose-containing solution to prolong plasma pyrophosphate levels. This maneuver significantly reduced both the incidence and amount of calcification. Quantitative histomorphometry of bone samples after double-labeling with calcein indicated that there was no effect of pyrophosphate on the rates of bone formation or mineralization. Thus, exogenous pyrophosphate can inhibit uremic vascular calcification without producing adverse effects on bone. PMID:21124302

Treatment with pyrophosphate inhibits uremic vascular calcification.

PubMed

O'Neill, W Charles; Lomashvili, Koba A; Malluche, Hartmut H; Faugere, Marie-Claude; Riser, Bruce L

2011-03-01

Pyrophosphate, which may be deficient in advanced renal failure, is a potent inhibitor of vascular calcification. To explore its use as a potential therapeutic, we injected exogenous pyrophosphate subcutaneously or intraperitoneally in normal rats and found that their plasma pyrophosphate concentrations peaked within 15 min. There was a single exponential decay with a half-life of 33 min. The kinetics were indistinguishable between the two routes of administration or in anephric rats. The effect of daily intraperitoneal pyrophosphate injections on uremic vascular calcification was then tested in rats fed a high-phosphate diet containing adenine for 28 days to induce uremia. Although the incidence of aortic calcification varied and was not altered by pyrophosphate, the calcium content of calcified aortas was significantly reduced by 70%. Studies were repeated in uremic rats given calcitriol to produce more consistent aortic calcification and treated with sodium pyrophosphate delivered intraperitoneally in a larger volume of glucose-containing solution to prolong plasma pyrophosphate levels. This maneuver significantly reduced both the incidence and amount of calcification. Quantitative histomorphometry of bone samples after double-labeling with calcein indicated that there was no effect of pyrophosphate on the rates of bone formation or mineralization. Thus, exogenous pyrophosphate can inhibit uremic vascular calcification without producing adverse effects on bone.

Experimental Determination of Solubilities of Sodium Polyborates In MgCl 2 Solutions: Solubility Constant of Di-Sodium Hexaborate Tetrahydrate, and Implications For the Diagenetic Formation of Ameghinite

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

Xiong, Yongliang; Kirkes, Leslie; KNOX, Jandi

In this paper, solubility measurements were conducted for sodium polyborates in MgCl 2 solutions at 22.5 ± 0.5 °C. According to solution chemistry and XRD patterns, di-sodium tetraborate decahydrate (borax) dissolves congruently, and is the sole solubility-controlling phase, in a 0.01 mol/kg MgCl 2 solution: Na 2B 4O 7•10H 2O(cr) ⇌ 2Na + + 4B(OH) 4 + 2H + + H 2O(l). However, in a 0.1 mol/kg MgCl 2 solution borax dissolves incongruently and is in equilibrium with di-sodium hexaborate tetrahydrate: 2Na 2B 6O 10•4H 2O(cr) + 2Na + + 23H 2O(l) ⇌ 3Na 2B 4O 7•10H 2O(cr) + 2Hmore » +. In this study, the equilibrium constant (log K 0) for Reaction 2 at 25 °C and infinite dilution was determined to be –16.44 ± 0.13 (2σ) based on the experimental data and the Pitzer model for calculations of activity coefficients of aqueous species. In accordance with the log K 0 for Reaction 1 from a previous publication from this research group, and log K 0 for Reaction 2 from this study, the equilibrium constant for dissolution of di-sodium hexaborate tetrahydrate at 25 °C and at infinite dilution, Na 2B 6O 10•4H 2O(cr) + 10H 2O(l) ⇌ 2Na + + 6B(OH) 4 - + 4H + was derived to be –45.42 ± 0.16 (2σ). The equilibrium constants determined in this study can find applications in many fields. For example, in the field of nuclear waste management, the formation of di-sodium hexaborate tetrahydrate in brines containing magnesium will decrease borate concentrations, making less borate available for interactions with Am(III). In the field of experimental investigations, based on the equilibrium constant for Reaction 2, the experimental systems can be controlled in terms of acidity around neutral pH by using the equilibrium assemblage of borax and di-sodium hexaborate tetrahydrate at 25 °C. As salt lakes and natural brines contain both borate and magnesium as well as sodium, the formation of sodium hexaborate tetrahydrate may influence the chemical evolution of salt lakes

Experimental Determination of Solubilities of Sodium Polyborates In MgCl 2 Solutions: Solubility Constant of Di-Sodium Hexaborate Tetrahydrate, and Implications For the Diagenetic Formation of Ameghinite

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie; KNOX, Jandi; ...

2017-11-01

In this paper, solubility measurements were conducted for sodium polyborates in MgCl 2 solutions at 22.5 ± 0.5 °C. According to solution chemistry and XRD patterns, di-sodium tetraborate decahydrate (borax) dissolves congruently, and is the sole solubility-controlling phase, in a 0.01 mol/kg MgCl 2 solution: Na 2B 4O 7•10H 2O(cr) ⇌ 2Na + + 4B(OH) 4 + 2H + + H 2O(l). However, in a 0.1 mol/kg MgCl 2 solution borax dissolves incongruently and is in equilibrium with di-sodium hexaborate tetrahydrate: 2Na 2B 6O 10•4H 2O(cr) + 2Na + + 23H 2O(l) ⇌ 3Na 2B 4O 7•10H 2O(cr) + 2Hmore » +. In this study, the equilibrium constant (log K 0) for Reaction 2 at 25 °C and infinite dilution was determined to be –16.44 ± 0.13 (2σ) based on the experimental data and the Pitzer model for calculations of activity coefficients of aqueous species. In accordance with the log K 0 for Reaction 1 from a previous publication from this research group, and log K 0 for Reaction 2 from this study, the equilibrium constant for dissolution of di-sodium hexaborate tetrahydrate at 25 °C and at infinite dilution, Na 2B 6O 10•4H 2O(cr) + 10H 2O(l) ⇌ 2Na + + 6B(OH) 4 - + 4H + was derived to be –45.42 ± 0.16 (2σ). The equilibrium constants determined in this study can find applications in many fields. For example, in the field of nuclear waste management, the formation of di-sodium hexaborate tetrahydrate in brines containing magnesium will decrease borate concentrations, making less borate available for interactions with Am(III). In the field of experimental investigations, based on the equilibrium constant for Reaction 2, the experimental systems can be controlled in terms of acidity around neutral pH by using the equilibrium assemblage of borax and di-sodium hexaborate tetrahydrate at 25 °C. As salt lakes and natural brines contain both borate and magnesium as well as sodium, the formation of sodium hexaborate tetrahydrate may influence the chemical evolution of salt lakes

Enhanced triterpene accumulation in Panax ginseng hairy roots overexpressing mevalonate-5-pyrophosphate decarboxylase and farnesyl pyrophosphate synthase.

PubMed

Kim, Yong-Kyoung; Kim, Yeon Bok; Uddin, Md Romij; Lee, Sanghyun; Kim, Soo-Un; Park, Sang Un

2014-10-17

To elucidate the function of mevalonate-5-pyrophosphate decarboxylase (MVD) and farnesyl pyrophosphate synthase (FPS) in triterpene biosynthesis, the genes governing the expression of these enzymes were transformed into Panax ginseng hairy roots. All the transgenic lines showed higher expression levels of PgMVD and PgFPS than that by the wild-type control. Among the hairy root lines transformed with PgMVD, M18 showed the highest level of transcription compared to the control (14.5-fold higher). Transcriptions of F11 and F20 transformed with PgFPS showed 11.1-fold higher level compared with control. In triterpene analysis, M25 of PgMVD produced 4.4-fold higher stigmasterol content (138.95 μg/100 mg, dry weight [DW]) than that by the control; F17 of PgFPS showed the highest total ginsenoside (36.42 mg/g DW) content, which was 2.4-fold higher compared with control. Our results indicate that metabolic engineering in P. ginseng was successfully achieved through Agrobacterium rhizogenes-mediated transformation and that the accumulation of phytosterols and ginsenosides was enhanced by introducing the PgMVD and PgFPS genes into the hairy roots of the plant. Our results suggest that PgMVD and PgFPS play an important role in the triterpene biosynthesis of P. ginseng.

Na(7)Mg(13)Nd(PO(4))(12).

PubMed

Jerbi, Hasna; Hidouri, Mourad; Mongi, Ben Amara

2012-06-01

Investigations of the quasi-ternary system Na(3)PO(4)-Mg(3)(PO(4))(2)-NdPO(4) allowed us to obtain the new phosphate hepta-sodium trideca-magnesium neodymium dodeca-kis-phosphate, Na(7)Mg(13)Nd(PO(4))(12), by applying a flux method. The crystal structure is isotypic with that of the previously reported Na(7)Mg(13)Ln(PO(4))(12) (Ln = Eu, La) compounds. It consists of a complex three-dimensional framework built up from an NdO(8) polyhedron (m symmetry), an MO(6) octa-hedron statistically occupied by M = Mg and Na, and eight MgO(x) (x = 5, 6) polyhedra (four with site symmetry m), linked either directely by sharing corners, edges and faces, or by one of the eight unique PO(4) tetra-hedra through common corners. Two of the PO(4) tetra-hedra are statisticaly disordered over a mirror plane. The whole structure can be described as resutling from an assembly of two types of structural units, viz [Mg(4)MP(4)O(22)](∞) (2) layers extending parallel to (100) and stacked along [100], and [Mg(4)NdP(4)O(36)](∞) (1) undulating chains running along the [010] direction. The six different Na(+) cations (five with site symmetry m and one with 0.5 occupancy) are situated in six distinct cavities delimited by the framework. The structure was refined from data of a racemic twin.

Thermodynamic description of Tc(iv) solubility and carbonate complexation in alkaline NaHCO3-Na2CO3-NaCl systems.

PubMed

Baumann, A; Yalçıntaş, E; Gaona, X; Polly, R; Dardenne, K; Prüßmann, T; Rothe, J; Altmaier, M; Geckeis, H

2018-03-28

The solubility of 99 Tc(iv) was investigated in dilute to concentrated carbonate solutions (0.01 M ≤ C tot ≤ 1.0 M, with C tot = [HCO 3 - ] + [CO 3 2- ]) under systematic variation of ionic strength (I = 0.3-5.0 M NaHCO 3 -Na 2 CO 3 -NaCl-NaOH) and pH m (-log[H + ] = 8.5-14.5). Strongly reducing conditions (pe + pH m ≈ 2) were set with Sn(ii). Carbonate enhances the solubility of Tc(iv) in alkaline conditions by up to 3.5 log 10 -units compared to carbonate-free systems. Solvent extraction and XANES confirmed that Tc was kept as +IV during the timeframe of the experiments (≤ 650 days). Solid phase characterization performed by XAFS, XRD, SEM-EDS, chemical analysis and TG-DTA confirmed that TcO 2 ·0.6H 2 O(am) controls the solubility of Tc(iv) under the conditions investigated. Slope analysis of the solubility data in combination with solid/aqueous phase characterization and DFT calculations indicate the predominance of the species Tc(OH) 3 CO 3 - at pH m ≤ 11 and C tot ≥ 0.01 M, for which thermodynamic and activity models are derived. Solubility data obtained above pH m ≈ 11 indicates the formation of previously unreported Tc(iv)-carbonate species, possibly Tc(OH) 4 CO 3 2- , although the likely formation of additional complexes prevents deriving a thermodynamic model valid for this pH m -region. This work provides the most comprehensive thermodynamic dataset available for the system Tc 4+ -Na + -Cl - -OH - -HCO 3 - -CO 3 2- -H 2 O(l) valid under a range of conditions relevant for nuclear waste disposal.

Modeling of glycine solubility in aqueous HCl-MgCl2 system and its application in phase transition of glycine by changing media and supersaturation

NASA Astrophysics Data System (ADS)

Ansari, Ziaul Haque; Zeng, Yan; Zhang, Yan; Demopoulos, George P.; Li, Zhibao

2017-06-01

The solubility of glycine in HCl and HCl-MgCl2 solutions was measured from 283.15 to 343.15 K and found to increase with temperature and increase linearly with the concentration of HCl. The MSE model integrated in the OLI platform was modified by regressing the experimental and literature solubility data through the adjustment of the middle-range interaction parameters. After parameterization, the model can accurately calculate the solubility with the average absolute deviation lower than 3.5% and thus be able to predict supersaturation of glycine. Crystallization of different polymorphs of glycine in water, HCl, NaOH, MgCl2, and HCl-MgCl2 aqueous solutions was performed. The effects of medium, temperature, supersaturation, and time on the crystallization were investigated. It was found that only in the HCl solution the formation of single α-glycine phase was achieved under all the investigated temperature and holding time. α-glycine or its mixture with γ-glycine or C4H18N2O4·HCl was produced in systems other than HCl solution depending on the conditions.

Solubility of KF and NaCl in water by molecular simulation.

PubMed

Sanz, E; Vega, C

2007-01-07

The solubility of two ionic salts, namely, KF and NaCl, in water has been calculated by Monte Carlo molecular simulation. Water has been modeled with the extended simple point charge model (SPC/E), ions with the Tosi-Fumi model and the interaction between water and ions with the Smith-Dang model. The chemical potential of the solute in the solution has been computed as the derivative of the total free energy with respect to the number of solute particles. The chemical potential of the solute in the solid phase has been calculated by thermodynamic integration to an Einstein crystal. The solubility of the salt has been calculated as the concentration at which the chemical potential of the salt in the solution becomes identical to that of the pure solid. The methodology used in this work has been tested by reproducing the results for the solubility of KF determined previously by Ferrario et al. [J. Chem. Phys. 117, 4947 (2002)]. For KF, it was found that the solubility of the model is only in qualitative agreement with experiment. The variation of the solubility with temperature for KF has also been studied. For NaCl, the potential model used predicts a solubility in good agreement with the experimental value. The same is true for the hydration chemical potential at infinite dilution. Given the practical importance of solutions of NaCl in water the model used in this work, whereas simple, can be of interest for future studies.

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

PubMed

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

2014-01-01

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

21 CFR 182.6789 - Tetra sodium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Tetra sodium pyrophosphate. 182.6789 Section 182.6789 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6789 Tetra sodium pyrophosphate. (a) Product. Tetra sodium pyrophosphate. (b) Conditions of use. This...

21 CFR 182.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium acid pyrophosphate. 182.1087 Section 182.1087 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b...

21 CFR 582.5306 - Ferric sodium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Dietary Supplements 1 § 582.5306 Ferric sodium pyrophosphate. (a) Product. Ferric sodium pyrophosphate. (b...

21 CFR 182.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium acid pyrophosphate. 182.1087 Section 182...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally...

21 CFR 582.6789 - Tetra sodium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Tetra sodium pyrophosphate. 582.6789 Section 582.6789 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....6789 Tetra sodium pyrophosphate. (a) Product. Tetra sodium pyrophosphate. (b) Conditions of use. This...

21 CFR 182.6789 - Tetra sodium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Tetra sodium pyrophosphate. 182.6789 Section 182...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 1 § 182.6789 Tetra sodium pyrophosphate. (a) Product. Tetra sodium pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when...

21 CFR 182.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium acid pyrophosphate. 182.1087 Section 182.1087 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b...

21 CFR 182.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium acid pyrophosphate. 182.1087 Section 182.1087 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b...

21 CFR 582.5223 - Calcium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use...

21 CFR 582.5223 - Calcium pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use...

21 CFR 582.5223 - Calcium pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use...

21 CFR 582.5223 - Calcium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use...

21 CFR 582.5223 - Calcium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5223 Calcium pyrophosphate. (a) Product. Calcium pyrophosphate. (b) Conditions of use...

21 CFR 582.5304 - Ferric pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use. This...

21 CFR 582.5304 - Ferric pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use. This...

21 CFR 582.5304 - Ferric pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use. This...

21 CFR 582.5304 - Ferric pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use. This...

21 CFR 582.5304 - Ferric pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5304 Ferric pyrophosphate. (a) Product. Ferric pyrophosphate. (b) Conditions of use. This...

Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

PubMed Central

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

2014-01-01

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

Electronic structure of lead pyrophosphate

NASA Astrophysics Data System (ADS)

Suewattana, Malliga; Singh, David

2007-03-01

Lead Pyrophosphate Pb2P2O7 is of interest for potential radiation detection applications and use in long term waste storage. It forms in triclinic P1 crystals and can also be grown as glasses. We performed electronic structure calculations using the crystal structure which determined by Mullica et. al (J. Solid State Chem (1986)) using x-ray diffraction and found large forces on atoms suggesting that the refined atomic positions were not fully correct. Here we report first principles structure relaxation and a revised crystal structure for this compound. We analyze the resulting structure using pair distribution functions and discuss the implications for the electronic properties. This work was supported by DOE NA22 and the Office of Naval Research.

24Mg(p, α) 21Na reaction study for spectroscopy of 21Na

DOE PAGES

Cha, S. M.; Chae, K. Y.; Kim, A.; ...

2015-11-03

The Mg-24(p, alpha)Na-21 reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain the spins and parities of the energy levels in Na-21 for the astrophysically important F-17(alpha, p)Ne-20 reaction rate calculation. 31-MeV proton beams from the 25-MV tandem accelerator and enriched Mg-24 solid targets were used. When recoiling He-4 particles from the Mg-24(p, alpha)Na-21 reaction we used a highly segmented silicon detector array to detect them; it measured the yields of He-4 particles over a range of angles simultaneously. A observed a new level at 6661 ± 5 keVmore » in the present work. The extracted angular distributions for the first four levels of Na-21 and the results from distorted wave Born approximation (DWBA) calculations were compared to verify and extract the angular momentum transfer.« less

Interpretation of Na-K-Mg relations in geothermal waters

USGS Publications Warehouse

Fournier, R.O.

1990-01-01

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

Crystal structure and europium luminescence of NaMgH3-xFx

NASA Astrophysics Data System (ADS)

Pflug, Christian; Franz, Alexandra; Kohlmann, Holger

2018-02-01

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

Stimulation of inorganic pyrophosphate elaboration by cultured cartilage and chondrocytes.

PubMed

Ryan, L M; Kurup, I; Rosenthal, A K; McCarty, D J

1989-08-01

Inorganic pyrophosphate elaboration by articular cartilage may favor calcium pyrophosphate dihydrate crystal deposition. Frequently crystal deposits form in persons affected with metabolic diseases. The cartilage organ culture system was used to model these metabolic conditions while measuring the influence on extracellular pyrophosphate elaboration. Alterations of ambient pH, thyroid stimulating hormone levels, and parathyroid hormone levels did not change pyrophosphate accumulation in the media. However, subphysiologic ambient calcium concentrations (25, 100, 500 microM) increased pyrophosphate accumulation about chondrocytes 3- to 10-fold. Low calcium also induced release of [14C]adenine-labeled nucleotides from chondrocytes, potential substrates for generation of extracellular pyrophosphate by ectoenzymes. Exposing cartilage to 10% fetal bovine serum also enhanced by 50% the egress of inorganic pyrophosphate from the tissue.

23Na NUCLEAR MAGNETIC RESONANCE RELAXATION STUDIES OF SODIUM ION INTERACTION WITH SOLUBLE RNA*

PubMed Central

James, Thomas L.; Noggle, Joseph H.

1969-01-01

Interactions between 23Na+ and soluble RNA in aqueous solution are studied with the use of 23Na nuclear magnetic resonance. At low concentrations of NaCl, the interactions obey a simple equilibrium model with a formation constant log (Kf)3 = 2.8 ± 0.3. The relaxation rate of the bound sodium is found to be T1B-1 = 222 ± 19 sec-1 compared to that of free sodium T1F-1 = 17.5 sec-1. At high NaCl concentrations, the system deviates from the model, possibly owing to aggregation of the soluble RNA. PMID:5256995

Solubility of NaCl and KCl in aqueous HCl from 20 to 85°C

USGS Publications Warehouse

Potter, Robert W.; Clynne, Michael A.

1980-01-01

The solubilities of NaCl and KCl in aqueous HCl solutions were determined from 20 to 85°C at concentrations ranging from 0 to 20 g of HCl/100 g of solution. Equations are given that describe the solubilities over the range of conditions studied. For NaCl and KCl respectively measured solubilities show an average deviation from these equations of ??0.10 and ??0.08 g/100 g of saturated solution.

21 CFR 182.8223 - Calcium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium pyrophosphate. 182.8223 Section 182.8223 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium pyrophosphate. (a) Product. Calcium...

21 CFR 582.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Additives § 582.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or...

21 CFR 582.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Additives § 582.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or...

21 CFR 582.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Additives § 582.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or...

21 CFR 582.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Additives § 582.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or...

21 CFR 582.1087 - Sodium acid pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Additives § 582.1087 Sodium acid pyrophosphate. (a) Product. Sodium acid pyrophosphate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or...

21 CFR 182.6787 - Sodium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium pyrophosphate. 182.6787 Section 182.6787 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Sequestrants 1 § 182.6787 Sodium pyrophosphate. (a) Product. Sodium...

Solubility of triuranyl diphosphate tetrahydrate (TDT) and Na autunite at 23 and 50 degrees C

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

Armstrong, Christopher R.; Felmy, Andrew R.; Clark, Sue B.

2010-11-01

In this report we present experimental solubility data for well-characterized triuranyl diphosphate tetrahydrate (TDT: (UO2)(3)(PO4)(2)center dot 4H(2)O) and Na autunite (Na[UO2PO4]center dot xH(2)O) at 23 and 50 degrees C in NaClO4-HClO4 solutions at pC(H+) = 2. Duplicate samples of TDT in 0.1, 0.5, 1.0, 2.0 and 5.0 in solutions were equilibrated at 23 and 50 degrees C. TDT solid was synthesized and characterized with ICP-OES, ATR-IR and powder XRD before and after solubility experiments. The pH of the suspensions were monitored throughout the experiments. Equilibrium was achieved from undersaturation with respect to TDT and oversaturation for Na autunite. Steady-state conditionsmore » were achieved in all cases within 82 d. TDT was unstable at ionic strengths above 0.1 m, where its complete conversion to Na autunite was observed. The ion-interaction model was used to interpret the experimental solubility data. The solubility product, log K-sp, for TDT was determined to be -49.7 and -51.3 at 23 and 50 degrees C respectively. log K for Na autunite was determined to be -24.4 (23 degrees C) and -24.1 +/- 0.2 (50 degrees C).« less

Enhancement of the Rate of Pyrophosphate Hydrolysis by Nonenzymatic Catalysts and by Inorganic Pyrophosphatase*

PubMed Central

Stockbridge, Randy B.; Wolfenden, Richard

2011-01-01

To estimate the proficiency of inorganic pyrophosphatase as a catalyst, 31P NMR was used to determine rate constants and thermodynamics of activation for the spontaneous hydrolysis of inorganic pyrophosphate (PPi) in the presence and absence of Mg2+ at elevated temperatures. These values were compared with rate constants and activation parameters determined for the reaction catalyzed by Escherichia coli inorganic pyrophosphatase using isothermal titration calorimetry. At 25 °C and pH 8.5, the hydrolysis of MgPPi2− proceeds with a rate constant of 2.8 × 10−10 s−1, whereas E. coli pyrophosphatase was found to have a turnover number of 570 s−1 under the same conditions. The resulting rate enhancement (2 × 1012-fold) is achieved entirely by reducing the enthalpy of activation (ΔΔH‡ = −16.6 kcal/mol). The presence of Mg2+ ions or the transfer of the substrate from bulk water to dimethyl sulfoxide was found to increase the rate of pyrophosphate hydrolysis by as much as ∼106-fold. Transfer to dimethyl sulfoxide accelerated PPi hydrolysis by reducing the enthalpy of activation. Mg2+ increased the rate of PPi hydrolysis by both increasing the entropy of activation and reducing the enthalpy of activation. PMID:21460215

Nitric oxide (NO), the only nitrogen monoxide redox form capable of activating soluble guanylyl cyclase.

PubMed

Dierks, E A; Burstyn, J N

1996-06-28

In the present study, we determined that of the redox forms of nitrogen monoxide, NO-, NO and NO+, only NO significantly activates soluble guanylyl cyclase (GTP pyrophosphate-lyase cyclizing, EC 4.6.1.2). Neither of the NO-donors tested, Angeli's salt (Na2N2O3) or Piloty's acid (C6H5SO2NHOH), caused a change in the guanylyl cyclase activity relative to the basal activity level. Interference by other reaction products was eliminated as a possible explanation for the lack of activation. To the extent that NO+ could be stabilized in aqueous solution, by dissolution of the nitrosonium salt NOPF6 in dry organic solvent prior to addition to the enzyme in buffer, NO+ had no effect on the activity of soluble guanylyl cyclase. The counter-ion, PF6-, had a minimal effect on the enzyme activity and, therefore was, not responsible for the lack of activation by NO+. These observations suggest that NO- is the natural activator of soluble guanylyl cyclase and is reasonably identical with endothelium-derived relaxing factor, the physiological regulator of soluble guanylyl cyclase activity.

Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0.5-2.79 GPa and 250-650 °C

NASA Astrophysics Data System (ADS)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; Chow, Paul; Xiao, Yuming; Hanchar, John M.; Tschauner, Oliver; Shen, Guoyin

2016-03-01

during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility.

High waterborne Mg does not attenuate the toxic effects of Fe, Mn, and Ba on Na+ regulation of Amazonian armored catfish tamoatá (Hoplosternum litoralle).

PubMed

Duarte, Rafael M; Benaduce, Ana Paula; Garcia, Luciano; Gomes, Levy C; Gomes, Adriana Chippari; Val, Adalberto L; Baldisserotto, Bernardo

2018-04-24

Formation water (FoW) is a by-product from oil and gas production and usually has high concentrations of soluble salts and metals. Calcium (Ca) and magnesium (Mg) have been shown to reduce the toxicity of metals to aquatic animals, and previous study showed that high waterborne Ca exerts mild effect against disturbances on Na + regulation in Amazonian armored catfish tamoatá (Hoplosternum littorale) acutely exposed to high Fe, Mn, and Ba levels. Here, we hypothesized that high Mg levels might also reduce the toxic effects of these metals on Na + regulation of tamoatá. The exposure to 5% FoW promoted an increase in Na + uptake and a rapid accumulation of Na + in all tissues analyzed (kidneyMg lowered Na + efflux rates and markedly inhibited Na + uptake, and also reduced both NKA activity and newly Na + accumulation in gills of fish. High Fe levels increased Na + net losses and inhibited Na + uptake in tamoatá. The diffusive Na + losses and the newly accumulated Na + in gills were reduced in fish exposed to high Mn and Ba. High waterborne Ba also inhibited NKA in gills, while both high Mn and Ba inhibited v-type H + -ATPase in kidney of tamoatá. High Mg did not lessen the toxic effect of Fe on Na + net fluxes, and reduced even more Na + uptake and the newly Na + accumulation in gills and plasma, and did not prevent the inhibition of both NKA and v-type H + -ATPases in kidney. Furthermore, Mg did not attenuate the effect of Mn on inhibition Na + uptake, keeping the activity of v-type H + -ATPase in kidney significantly lowered. High Mg levels mildly attenuated the effects of Ba in Na + balance by increasing the new accumulation of Na + in liver, and restore the activity of both NKA and v-type H + -ATPase in gills of tamoatá. Overall, high waterborne Mg does not have a strong contribution to, or have only minor effects, in protecting

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

PubMed

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

2003-09-15

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

Effect of dinucleoside pyrophosphates on the oligomerization of activated mononucleotides on Na(+)-montmorillonite: reaction of 5'-phosphoro-4-(dimethylamino)pyridinium [4-(CH3)2NpypA] with A5'ppA

NASA Technical Reports Server (NTRS)

Prabahar, K. J.; Ferris, J. P.

1997-01-01

The oligomerization of adenosine 5'-phosphoro-4-(dimethylamino)pyridinium (4-(CH3)2-NpypA) and diadenosine 5',5'-pyrophosphate (A5'ppA) (9:1) on Na(+)-montmorillonite was studied. The oligomers were isolated and analyzed by selective enzymatic hydrolyses and the oligomeric composition and the percent of 3',5'-phosphodiester linkages present in each fraction was determined. The longest oligomers formed (11-mers) are slightly shorter than those produced in the absence of A5'ppA (12-mers). Smaller amounts of A5'ppA are incorporated into the oligomers than in the ImpA/A5'ppA reaction. The regioselectivity of 3',5'-phosphodiester bond formation is comparable to that of the oligomerization of 4-(CH3)2NpypA alone. An explanation of these data is proposed and the possible effect of dinucleoside pyrophosphate on prebiotic RNA formation is discussed.

Formation of pyrophosphate on hydroxyapatite with thioesters as condensing agents

NASA Technical Reports Server (NTRS)

Weber, A. L.

1982-01-01

'Energy-rich' thioesters are shown to act as condensing agents in the formation of pyrophosphate on hydroxyapatite in the presence of water at ambient temperature. The yield of pyrophosphate based on thioester ranges from 2.5% to 11.4% and depends upon the pH and concentration of reactants. Reaction of 0.130 M hydroxyapatite suspended in a solution of 0.08 M sodium phosphate and 0.20 M imidazole hydrochloride (pH 7.0) with 0.10 M N,S-diacetylcysteamine for 6 days gives the highest yield of pyrophosphate (11.4%). Pyrophosphate formation requires the presence of hydroxyapatite, sodium phosphate and the thioester, N,S-diacetylcysteamine. The related thioester, N,S-diacetylcysteine, also yields pyrophosphate in reactions on hydroxyapatite.

Comparing soluble ferric pyrophosphate to common iron salts and chelates as sources of bioavailable iron in a Caco-2 cell culture model.

PubMed

Zhu, Le; Glahn, Raymond P; Nelson, Deanna; Miller, Dennis D

2009-06-10

Iron bioavailability from supplements and fortificants varies depending upon the form of the iron and the presence or absence of iron absorption enhancers and inhibitors. Our objectives were to compare the effects of pH and selected enhancers and inhibitors and food matrices on the bioavailability of iron in soluble ferric pyrophosphate (SFP) to other iron fortificants using a Caco-2 cell culture model with or without the combination of in vitro digestion. Ferritin formation was the highest in cells treated with SFP compared to those treated with other iron compounds or chelates. Exposure to pH 2 followed by adjustment to pH 7 markedly decreased FeSO(4) bioavailability but had a smaller effect on bioavailabilities from SFP and sodium iron(III) ethylenediaminetetraacetate (NaFeEDTA), suggesting that chelating agents minimize the effects of pH on iron bioavailability. Adding ascorbic acid (AA) and cysteine to SFP in a 20:1 molar ratio increased ferritin formation by 3- and 2-fold, respectively, whereas adding citrate had no significant effect on the bioavailability of SFP. Adding phytic acid (10:1) and tannic acid (1:1) to iron decreased iron bioavailability from SFP by 91 and 99%, respectively. The addition of zinc had a marked inhibitory effect on iron bioavailability. Calcium and magnesium also inhibited iron bioavailability but to a lesser extent. Incorporating SFP in rice greatly reduced iron bioavailability from SFP, but this effect can be partially reversed with the addition of AA. SFP and FeSO(4) were taken up similarly when added to nonfat dry milk. Our results suggest that dietary factors known to enhance and inhibit iron bioavailability from various iron sources affect iron bioavailability from SFP in similar directions. However, the magnitude of the effects of iron absorption inhibitors on SFP iron appears to be smaller than on iron salts, such as FeSO(4) and FeCl(3). This supports the hypothesis that SFP is a promising iron source for food fortification

pH-metric solubility. 2: correlation between the acid-base titration and the saturation shake-flask solubility-pH methods.

PubMed

Avdeef, A; Berger, C M; Brownell, C

2000-01-01

The objective of this study was to compare the results of a normal saturation shake-flask method to a new potentiometric acid-base titration method for determining the intrinsic solubility and the solubility-pH profiles of ionizable molecules, and to report the solubility constants determined by the latter technique. The solubility-pH profiles of twelve generic drugs (atenolol, diclofenac.Na, famotidine, flurbiprofen, furosemide, hydrochlorothiazide, ibuprofen, ketoprofen, labetolol.HCl, naproxen, phenytoin, and propranolol.HCl), with solubilities spanning over six orders of magnitude, were determined both by the new pH-metric method and by a traditional approach (24 hr shaking of saturated solutions, followed by filtration, then HPLC assaying with UV detection). The 212 separate saturation shake-flask solubility measurements and those derived from 65 potentiometric titrations agreed well. The analysis produced the correlation equation: log(1/S)titration = -0.063(+/- 0.032) + 1.025(+/- 0.011) log(1/S)shake-flask, s = 0.20, r2 = 0.978. The potentiometrically-derived intrinsic solubilities of the drugs were: atenolol 13.5 mg/mL, diclofenac.Na 0.82 microg/mL, famotidine 1.1 mg/ mL, flurbiprofen 10.6 microg/mL, furosemide 5.9 microg/mL, hydrochlorothiazide 0.70 mg/mL, ibuprofen 49 microg/mL, ketoprofen 118 microg/mL, labetolol.HCl 128 microg/mL, naproxen 14 microg/mL, phenytoin 19 microg/mL, and propranolol.HCl 70 microg/mL. The new potentiometric method was shown to be reliable for determining the solubility-pH profiles of uncharged ionizable drug substances. Its speed compared to conventional equilibrium measurements, its sound theoretical basis, its ability to generate the full solubility-pH profile from a single titration, and its dynamic range (currently estimated to be seven orders of magnitude) make the new pH-metric method an attractive addition to traditional approaches used by preformulation and development scientists. It may be useful even to discovery

Water soluble cations and the fluvial history of Mars

NASA Technical Reports Server (NTRS)

Silverman, M. P.; Munoz, E. F.

1975-01-01

The electrical conductivity and water soluble Na, K, Ca, and Mg of aqueous solutions of terrestrial soils and finely divided igneous and metamorphic rocks were determined. Soils from dry terrestrial basins with a history of water accumulation as well as soils from the topographic lows of valleys accumulated water soluble cations, particularly Na and Ca. These soils as a group can be distinguished from the rocks or a second group of soils (leached upland soils and soils from sites other than the topographic lows of valleys) by significant differences in their mean electrical conductivity and water-soluble Na + Ca content. Similar measurements on multiple samples from the surface of Mars, collected by an automated long-range roving vehicle along a highlands-to-basin transect at sites with morphological features resembling dry riverlike channels, are suggested to determine the fluvial history of the planet.

Investigating the influence of Na+ and Sr2+ on the structure and solubility of SiO2-TiO2-CaO-Na2O/SrO bioactive glass.

PubMed

Li, Y; Placek, L M; Coughlan, A; Laffir, F R; Pradhan, D; Mellott, N P; Wren, A W

2015-02-01

This study was conducted to determine the influence that network modifiers, sodium (Na+) and strontium (Sr2+), have on the solubility of a SiO2-TiO2-CaO-Na2O/SrO bioactive glass. Glass characterization determined each composition had a similar structure, i.e. bridging to non-bridging oxygen ratio determined by X-ray photoelectron spectroscopy. Magic angle spinning nuclear magnetic resonance (MAS-NMR) confirmed structural similarities as each glass presented spectral shifts between -84 and -85 ppm. Differential thermal analysis and hardness testing revealed higher glass transition temperatures (Tg 591-760 °C) and hardness values (2.4-6.1 GPa) for the Sr2+ containing glasses. Additionally the Sr2+ (~250 mg/L) containing glasses displayed much lower ion release rates than the Na+ (~1,200 mg/L) containing glass analogues. With the reduction in ion release there was an associated reduction in solution pH. Cytotoxicity and cell adhesion studies were conducted using MC3T3 Osteoblasts. Each glass did not significantly reduce cell numbers and osteoblasts were found to adhere to each glass surface.

An isopiestic study of aqueous NaBr and KBr at 50 °C: Chemical equilibrium model of solution behavior and solubility in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems to high concentration and temperature

NASA Astrophysics Data System (ADS)

Christov, Christomir

2007-07-01

The isopiestic method has been used to determine the osmotic coefficients of the binary solutions NaBr-H 2O (from 0.745 to 5.953 mol kg -1) and KBr-H 2O (from 0.741 to 5.683 mol kg -1) at the temperature t = 50 °C. Sodium chloride solutions have been used as isopiestic reference standards. The isopiestic results obtained have been combined with all other experimental thermodynamic quantities available in literature (osmotic coefficients, water activities, bromide mineral's solubilities) to construct a chemical model that calculates solute and solvent activities and solid-liquid equilibria in the NaBr-H 2O, KBr-H 2O and Na-K-Br-H 2O systems from dilute to high solution concentration within the 0-300 °C temperature range. The Harvie and Weare [Harvie C., and Weare J. (1980) The prediction of mineral solubilities in naturalwaters: the Na-K-Mg-Ca-Cl-SO 4-H 2O system from zero to high concentration at 25 °C. Geochim. Cosmochim. Acta44, 981-997] solubility modeling approach, incorporating their implementation of the concentration-dependent specific interaction equations of Pitzer [Pitzer K. (1973) Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem.77, 268-277] is employed. The model for binary systems is validated by comparing activity coefficient predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solutions model due to data insufficiencies are discussed. This model expands the variable temperature sodium-potassium model of Greenberg and Moller [Greenberg J., and Moller N. (1989) The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Cl-SO 4-H 2O system to high concentration from 0 to 250 °C. Geochim. Cosmochim. Acta53, 2503-2518] by evaluating Br - pure electrolyte and mixing solution parameters and the chemical potentials of three bromide solid phases: NaBr-2H 2O (cr), NaBr (cr) and KBr (cr).

Solubility of SC2O3 in NA3ALF6-K3ALF6-ALF3 Melts

NASA Astrophysics Data System (ADS)

Tian, Zhongliang; Hu, Xun; Lai, Yanqing; Yang, Shu; Ye, Shaolong; Li, Jie

The electrolyte with high solubility for Sc2O3 is very important to realize the preparation of Al-Sc master alloy by the molten salt electrolysis. The solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts is determined with an isothermal saturation method. The effects of KR (ratio of K3AlF6 to K3AlF6+Na3AlF6), the concentration of Al2O3 and the temperature on the solubility of Sc2O3 are also investigated. The results indicate that the solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts increases and then decreases with KR increasing. The solubility of Sc2O3 is 8.698 wt.% in (K3AlF6-Na3AlF6)(KR25%)-18 wt.%AlF3 melts at 940°C. The effect of temperature on the solubility is little, and the values are 8.575 wt.% and 8.762 wt.% respectively when the temperatures are 930°C and 960°C. The solubility decreases from 8.809 wt.% to 7.058 wt.% as the concentration of Al2O3 increases from 1.5 wt.% to 5.0 wt.% at 950°C.

Structure of Leishmania major Methionyl-tRNA Synthetase in Complex with Intermediate Products Methionyladenylate and Pyrophosphate

PubMed Central

Larson, Eric T.; Kim, Jessica E.; Zucker, Frank H.; Kelley, Angela; Mueller, Natascha; Napuli, Alberto J.; Verlinde, Christophe L.M.J.; Fan, Erkang; Buckner, Frederick S.; Van Voorhis, Wesley C.; Merritt, Ethan A.; Hol, Wim G.J.

2011-01-01

Leishmania parasites cause two million new cases of leishmaniasis each year with several hundreds of millions people at risk. Due to the paucity and shortcomings of available drugs, we have undertaken the crystal structure determination of a key enzyme from Leishmania major in hopes of creating a platform for the rational design of new therapeutics. Crystals of the catalytic core of methionyl-tRNA synthetase from L. major (LmMetRS) were obtained with the substrates MgATP and methionine present in the crystallization medium. These crystals yielded the 2.0 Å resolution structure of LmMetRS in complex with two products, methionyladenylate and pyrophosphate, along with a Mg2+ ion that bridges them. This is the first class I aminoacyl-tRNA synthetase (aaRS) structure with pyrophosphate bound. The residues of the class I aaRS signature sequence motifs, KISKS and HIGH, make numerous contacts with the pyrophosphate. Substantial differences between the LmMetRS structure and previously reported complexes of E. coli MetRS (EcMetRS) with analogs of the methionyladenylate intermediate product are observed, even though one of these analogs only differs by one atom from the intermediate. The source of these structural differences is attributed to the presence of the product pyrophosphate in LmMetRS. Analysis of the LmMetRS structure in light of the Aquifex aeolicus MetRS-tRNAMet complex shows that major rearrangements of multiple structural elements of enzyme and/or tRNA are required to allow the CCA acceptor triplet to reach the methionyladenylate intermediate in the active site. Comparison with sequences of human cytosolic and mitochondrial MetRS reveals interesting differences near the ATP- and methionine-binding regions of LmMetRS, suggesting that it should be possible to obtain compounds that selectively inhibit the parasite enzyme. PMID:21144880

Solubility relations in the ternary system NaCl-CsCl-H2O at 1 atm. 1. Solubilities of halite from 20 to 100 °C

USGS Publications Warehouse

Chou, I.-Ming; Lee, R.D.

1983-01-01

Solubilities of halite in the ternary system NaCl-CsCl-H2O have been determined by the visual polythermal method at 1 atm from 20 to 100??C along five constant CsCl/(CsCl + H2O) weight ratio lines. These five constant weight ratios are 0.1, 0.2, 0.3, 0.4, and 0.5. The maximum uncertainties in these measurements are ??0.02 wt % NaCl and ??0.15??C. The data along each constant CsCl/(CsCl + H2O) weight ratio line were regressed to a smooth curve. The maximum deviation of the measured solubilities from the smooth curves is 0.06 wt % NaCl. Isothermal solubilities of halite were calculated from smoothed curves at 25, 50, and 75??C.

Rutile solubility in NaF–NaCl–KCl-bearing aqueous fluids at 0.5–2.79GPa and 250–650°C

DOE PAGES

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; ...

2016-01-14

/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Investigating the pharmacodynamic and magnetic properties of pyrophosphate-bridged coordination complexes

NASA Astrophysics Data System (ADS)

Ikotun, Oluwatayo (Tayo) F.

The multidentate nature of pyrophosphate makes it an attractive ligand for complexation of metal cations. The participation of pyrophosphate in a variety of biological pathways and its metal catalyzed hydrolysis has driven our investigation into its coordination chemistry. We have successfully synthesized a library of binuclear pyrophosphate bridge coordination complexes. The problem of pyrophosphate hydrolysis to phosphate in the presence of divalent metal ions was overcome by incorporating capping ligands such as 1,10-phenanthroline and 2,2'-bipyridine prior to the addition of the pyrophosphate. The magnetic properties of these complexes was investigated and magneto-structural analysis was conducted. The biological abundance of pyrophosphate and the success of metal based drugs such as cisplatin, prompted our investigation of the cytotoxic properties of M(II) pyrophosphate dimeric complexes (where M(II) is CoII, CuII, and NiII) in adriamycin resistant human ovarian cancer cells. Thess compounds were found to exhibit toxicity in the nanomolar to picomolar range. We conducted in vitro stability studies and the mechanism of cytoxicity was elucidated by performing DNA mobility and binding assays, enzyme inhibition assays, and in vitro oxidative stress studies.

Calcium pyrophosphate dihydrate gout and other crystal deposition diseases.

PubMed

Reginato, A J

1991-08-01

The number of crystal or birefringent particles associated with arthritis is increasing, and a uniform taxonomy is needed. The term gout has been proposed as a generic term for these diseases based on historical, clinical, and crystallographic reasons. Calcium pyrophosphate dihydrate gout follows monosodium urate gout in frequency, and its spectrum of clinical manifestations continues to grow. Familial calcium pyrophosphate dihydrate gout was described for the first time in kindreds studied in England and Tunisia; new Jewish and Spanish kindreds were also reported. Type I collagen was shown to nucleate nativelike calcium pyrophosphate dihydrate crystals, and pyrophosphate elaboration was explored in cartilage explants in an attempt to reproduce the in vivo metabolic or endocrine disorders associated with calcium pyrophosphate dihydrate gout. The effect of pyrophosphatase and different cofactors such as magnesium in dissolving calcium pyrophosphate dihydrate crystals was investigated. High-resolution electron microscopy was used to study the interrelation between apatite and other basic calcium phosphate crystals in apatite gout. Raman microscopy was applied for the first time to identify crystals in biologic specimens. A simple and specific technique for basic calcium phosphate crystal identification is necessary to understand the relationship between different calcium phosphate crystals and osteoarthritis. Several reports about children and young patients with primary oxalate gout described the effect of oxalate on eyes, periodontal tissues, and bone. Multicenter studies showed poor results of renal transplantation, but favored combined liver and renal transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

The characteristics of pyrophosphate: D-fructose-6-phosphate 1-phosphotransferases from Sansevieria trifasciata leaves and Phaseolus coccineus stems.

PubMed

Kowalczyk, S

1987-01-01

Three different molecular forms of pyrophosphate-dependent phosphofructokinase have been isolated: one from Sansevieria trifasciata leaves and two from Phaseolus coccineus stems. The form isolated from S. trifasciata has the molecular weight of about 115,000. The apparent molecular weights for the two forms from mung bean were approximately 220,000 and 450,000. All three forms have the same pH optima, an absolute requirement for Mg2+ ions both in the forward and reverse reaction, but differ in their sensitivity toward fructose 2,6-bisphosphate. Kinetic properties of the partially purified enzymes have been investigated in the presence and absence of fructose 2,6-bisphosphate. Pyrophosphate-dependent phosphofructokinase from S. trifasciata exhibited hyperbolic kinetics with all substrates tested. The saturation curves of the enzyme (form A) from mung bean for pyrophosphate, fructose 6-phosphate and fructose 1,6-bisphosphate were sigmoidal in the absence of fructose 2,6-bisphosphate. In the presence of fructose 2,6-bisphosphate these kinetics became hyperbolic.

ALKYL PYROPHOSPHATE METAL SOLVENT EXTRACTANTS AND PROCESS

DOEpatents

Long, R.L.

1958-09-30

A process is presented for the recovery of uranium from aqueous mineral acidic solutions by solvent extraction. The extractant is a synmmetrical dialkyl pyrophosphate in which the alkyl substituents have a chain length of from 4 to 17 carbon atoms. Mentioned as a preferred extractant is dioctyl pyrophosphate. The uranium is precipitated irom the organic extractant phase with an agent such as HF, fluoride salts. alcohol, or ammonia.

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

NASA Astrophysics Data System (ADS)

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

2005-12-01

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

Co-intercalation of Mg(2+) and Na(+) in Na(0.69)Fe2(CN)6 as a High-Voltage Cathode for Magnesium Batteries.

PubMed

Kim, Dong-Min; Kim, Youngjin; Arumugam, Durairaj; Woo, Sang Won; Jo, Yong Nam; Park, Min-Sik; Kim, Young-Jun; Choi, Nam-Soon; Lee, Kyu Tae

2016-04-06

Thanks to the advantages of low cost and good safety, magnesium metal batteries get the limelight as substituent for lithium ion batteries. However, the energy density of state-of-the-art magnesium batteries is not high enough because of their low operating potential; thus, it is necessary to improve the energy density by developing new high-voltage cathode materials. In this study, nanosized Berlin green Fe2(CN)6 and Prussian blue Na(0.69)Fe2(CN)6 are compared as high-voltage cathode materials for magnesium batteries. Interestingly, while Mg(2+) ions cannot be intercalated in Fe2(CN)6, Na(0.69)Fe2(CN)6 shows reversible intercalation and deintercalation of Mg(2+) ions, although they have the same crystal structure except for the presence of Na(+) ions. This phenomenon is attributed to the fact that Mg(2+) ions are more stable in Na(+)-containing Na(0.69)Fe2(CN)6 than in Na(+)-free Fe2(CN)6, indicating Na(+) ions in Na(0.69)Fe2(CN)6 plays a crucial role in stabilizing Mg(2+) ions. Na(0.69)Fe2(CN)6 delivers reversible capacity of approximately 70 mA h g(-1) at 3.0 V vs Mg/Mg(2+) and shows stable cycle performance over 35 cycles. Therefore, Prussian blue analogues are promising structures for high-voltage cathode materials in Mg batteries. Furthermore, this co-intercalation effect suggests new avenues for the development of cathode materials in hybrid magnesium batteries that use both Mg(2+) and Na(+) ions as charge carriers.

Familial pyrophosphate arthropathy. Occurrence and Crystal Identification.

PubMed

Bjelle, A

1981-01-01

Hereditary pyrophosphate arthropathy has been observed in three Swedish families and in a few other caucasian populations. The inheritance is most probably autosomal dominant with a variable penetrance. The most severe cases have been found in homozygotes among isolates of immigrants in Slovakia and Chile. Studies on genetic and etio-pathogenetic factors in hereditary pyrophosphate arthropathy, and the utilization of new diagnostic techniques for crystal identification, are important approaches towards a further understanding of the disease.

Controllable Fabrication of Amorphous Co-Ni Pyrophosphates for Tuning Electrochemical Performance in Supercapacitors.

PubMed

Chen, Chen; Zhang, Ning; He, Yulu; Liang, Bo; Ma, Renzhi; Liu, Xiaohe

2016-09-07

Incorporation of two transition metals offers an effective method to enhance the electrochemical performance in supercapacitors for transition metal compound based electrodes. However, such a configuration is seldom concerned in pyrophosphates. Here, amorphous phase Co-Ni pyrophosphates are fabricated as electrodes in supercapacitors. Through controllably adjusting the ratios of Co and Ni as well as the calcination temperature, the electrochemical performance can be tuned. An optimized amorphous Ni-Co pyrophosphate exhibits much higher specific capacitance than monometallic Ni and Co pyrophosphates and shows excellent cycling ability. When employing Ni-Co pyrophosphates as positive electrode and activated carbon as a negative electrode, the fabricated asymmetric supercapacitor cell exhibits favorable capacitance and cycling ability. This study provides facile methods to improve the transition metal pyrophosphate electrodes for efficient electrodes in electrochemical energy storage devices.

Temperature-dependent solubility transition of Na₂SO₄ in water and the effect of NaCl therein: solution structures and salt water dynamics.

PubMed

Bharmoria, Pankaj; Gehlot, Praveen Singh; Gupta, Hariom; Kumar, Arvind

2014-11-06

Dual, aqueous solubility behavior of Na2SO4 as a function of temperatures is still a natural enigma lying unresolved in the literature. The solubility of Na2SO4 increases up to 32.38 °C and decreases slightly thereafter at higher temperatures. We have thrown light on this phenomenon by analyzing the Na2SO4-water clusters (growth and stability) detected from temperature-dependent dynamic light scattering experiments, solution compressibility changes derived from the density and speed of sound measurements, and water structural changes/Na2SO4 (ion pair)-water interactions observed from the FT-IR and 2D DOSY (1)H NMR spectroscopic investigations. It has been observed that Na2SO4-water clusters grow with an increase in Na2SO4 concentration (until the solubility transition temperature) and then start decreasing afterward. An unusual decrease in cluster size and solution compressibility has been observed with the rise in temperature for the Na2SO4 saturated solutions below the solubility transition temperature, whereas an inverse pattern is followed thereafter. DOSY experiments have indicated different types of water cluster species in saturated solutions at different temperatures with varying self-diffusion coefficients. The effect of NaCl (5-15 wt %) on the solubility behavior of Na2SO4 at different temperatures has also been examined. The studies are important from both fundamental and industrial application points of view, for example, toward the clean separation of NaCl and Na2SO4 from the effluent streams of textile and tannery industries.

Mechanism of Mg2+-Accompanied Product Release in Sugar Nucleotidyltransferases.

PubMed

Vithani, Neha; Ankush Jagtap, Pravin Kumar; Verma, Sunil Kumar; Tripathi, Ravi; Awasthi, Shalini; Nair, Nisanth N; Prakash, Balaji

2018-03-06

The nucleotidyl transfer reaction, catalyzed by sugar nucleotidyltransferases (SNTs), is assisted by two active site Mg 2+ ions. While studying this reaction using X-ray crystallography, we captured snapshots of the pyrophosphate (product) as it exits along a pocket. Surprisingly, one of the active site Mg 2+ ions remains coordinated to the exiting pyrophosphate. This hints at the participation of Mg 2+ in the process of product release, besides its role in catalyzing nucleotidyl transfer. These observations are further supported by enhanced sampling molecular dynamics simulations. Free energy computations suggest that the product release is likely to be rate limiting in SNTs, and the origin of the high free energy barrier for product release could be traced back to the "slow" conformational change of an Arg residue at the exit end of the pocket. These results establish a dual role for Mg 2+ , and propose a general mechanism of product release during the nucleotidyl transfer by SNTs. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Thiamin Pyrophosphate-Motif

NASA Technical Reports Server (NTRS)

Dominiak, P.; Ciszak, E.

2003-01-01

Using databases the authors have identified a common thiamin pyrophosphate (TPP)-motif in the family of functionally diverse TPP-dependent enzymes. This common motif consists of multimeric organization of subunits and two catalytic centers. Each catalytic center (PP:PYR) is formed at the interface of the PP-domain binding the magnesium ion, pyrophosphate and amhopyrimidine ring of TPP, and the PYR-domain binding the aminopyrimidine ring of that cofactor. A pair of these catalytic centers constitutes the catalytic core (PP:PYR)(sub 2) within these enzymes. Analysis of the structural elements of this catalytic core reveals novel definition of the common amino acid sequences, which are GXPhiX(sub 4)(G)PhiXXGQ and GDGX(sub 25-30)NN in the PP-domain, and the EX(sub 4)(G)PhiXXGPhi in the PYR-domain, where Phi corresponds to a hydrophobic amino acid. This TPP-motif provides a novel tool for annotation of TPP-dependent enzymes useful in advancing functional proteomics.

The Thiamin Pyrophosphate-Motif

NASA Technical Reports Server (NTRS)

Dominiak, Paulina M.; Ciszak, Ewa M.

2003-01-01

Using databases the authors have identified a common thiamin pyrophosphate (TPP)-motif in the family of functionally diverse TPP-dependent enzymes. This common motif consists of multimeric organization of subunits, two catalytic centers, common amino acid sequence, and specific contacts to provide a flip-flop, or alternate site, mechanism of action. Each catalytic center [PP:PYR] is formed at the interface of the PP-domain binding the magnesium ion, pyrophosphate and aminopyrimidine ring of TPP, and the PYR-domain binding the aminopyrimidine ring of that cofactor. A pair of these catalytic centers constitutes the catalytic core [PP:PYR]* within these enzymes. Analysis of the structural elements of this catalytic core reveals novel definition of the common amino acid sequences, which are GX@&(G)@XXGQ, and GDGX25-30 within the PP- domain, and the E&(G)@XXG@ within the PYR-domain, where Q, corresponds to a hydrophobic amino acid. This TPP-motif provides a novel tool for annotation of TPP-dependent enzymes useful in advancing functional proteomics.

Two inositol hexakisphosphate kinases drive inositol pyrophosphate synthesis in plants

USDA-ARS?s Scientific Manuscript database

Inositol pyrophosphates are novel cellular signaling molecules with newly discovered roles in energy sensing and metabolic control. Studies in eukaryotes have revealed that these compounds turn over rapidly, and thus only small amounts accumulate. Inositol pyrophosphates have not been the subject of...

Technetium-99m Pyrophosphate: Comparison of ED50 for Tetany and Acidosis with Acute LD500

DTIC Science & Technology

electrocardiogram and chemical analysis revealed that the hypocalcemic effect occurs at a much lower dosage than for the LD50. Polyphosphate was found to be more...toxic by the LD50 analysis than pyrophosphate. It is emphasized that the hypocalcemic toxic effects should be the determining factor in deciding what...to 1 with regard to the first signs of hypocalcemia by electrocardiographic measurements (i.e., 2 mg/kg). On this basis an injection of no more than 1 mg/kg is recommended to maintain a safety factor of around 10 to 1.

Characterization of a soluble phosphatidic acid phosphatase in bitter melon (Momordica charantia).

PubMed

Cao, Heping; Sethumadhavan, Kandan; Grimm, Casey C; Ullah, Abul H J

2014-01-01

Momordica charantia is often called bitter melon, bitter gourd or bitter squash because its fruit has a bitter taste. The fruit has been widely used as vegetable and herbal medicine. Alpha-eleostearic acid is the major fatty acid in the seeds, but little is known about its biosynthesis. As an initial step towards understanding the biochemical mechanism of fatty acid accumulation in bitter melon seeds, this study focused on a soluble phosphatidic acid phosphatase (PAP, 3-sn-phosphatidate phosphohydrolase, EC 3.1.3.4) that hydrolyzes the phosphomonoester bond in phosphatidate yielding diacylglycerol and P(i). PAPs are typically categorized into two subfamilies: Mg(2+)-dependent soluble PAP and Mg(2+)-independent membrane-associated PAP. We report here the partial purification and characterization of an Mg(2+)-independent PAP activity from developing cotyledons of bitter melon. PAP protein was partially purified by successive centrifugation and UNOsphere Q and S columns from the soluble extract. PAP activity was optimized at pH 6.5 and 53-60 °C and unaffected by up to 0.3 mM MgCl2. The K(m) and Vmax values for dioleoyl-phosphatidic acid were 595.4 µM and 104.9 ηkat/mg of protein, respectively. PAP activity was inhibited by NaF, Na(3)VO(4), Triton X-100, FeSO4 and CuSO4, but stimulated by MnSO4, ZnSO4 and Co(NO3)2. In-gel activity assay and mass spectrometry showed that PAP activity was copurified with a number of other proteins. This study suggests that PAP protein is probably associated with other proteins in bitter melon seeds and that a new class of PAP exists as a soluble and Mg(2+)-independent enzyme in plants.

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

PubMed

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

2015-01-01

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

Consensus on the solubility of NaCl in water from computer simulations using the chemical potential route.

PubMed

Benavides, A L; Aragones, J L; Vega, C

2016-03-28

The solubility of NaCl in water is evaluated by using three force field models: Joung-Cheatham for NaCl dissolved in two different water models (SPC/E and TIP4P/2005) and Smith Dang NaCl model in SPC/E water. The methodology based on free-energy calculations [E. Sanz and C. Vega, J. Chem. Phys. 126, 014507 (2007)] and [J. L. Aragones et al., J. Chem. Phys. 136, 244508 (2012)] has been used, except, that all calculations for the NaCl in solution were obtained by using molecular dynamics simulations with the GROMACS package instead of homemade MC programs. We have explored new lower molalities and made longer runs to improve the accuracy of the calculations. Exploring the low molality region allowed us to obtain an analytical expression for the chemical potential of the ions in solution as a function of molality valid for a wider range of molalities, including the infinite dilute case. These new results are in better agreement with recent estimations of the solubility obtained with other methodologies. Besides, two empirical simple rules have been obtained to have a rough estimate of the solubility of a certain model, by analyzing the ionic pairs formation as a function of molality and/or by calculating the difference between the NaCl solid chemical potential and the standard chemical potential of the salt in solution.

Anoxic Corrosion of Steel and Lead in Na - Cl ± Mg-Dominated Brines in Atmospheres Containing CO2

NASA Astrophysics Data System (ADS)

Roselle, G. T.; Johnsen, S.; Allen, C.; Roselle, R.

2009-12-01

The Waste Isolation Pilot Plant (WIPP) is a deep geologic repository developed by the U.S. Department of Energy for the disposal of transuranic radioactive waste in bedded salt (Permian Salado Fm.). In order to minimize radionuclide release from the repository it is desirable to maintain these species in their least-soluble form (i.e., low oxidation states). Post-closure conditions in the WIPP will control the speciation and solubility of radionuclides in the waste. Microbially-produced CO2 from cellulosic, plastic and rubber materials in the waste may acidify any brine present and increase the actinide solubilities. Thus, the DOE emplaces MgO in the repository to buffer fCO2 and pH within ranges favoring lower actinide solubilities. Large quantities of low-C steel and Pb present in the WIPP may also consume CO2. We present initial results from a series of multiyear experiments investigating the corrosion of steel and Pb alloys under WIPP-relevant conditions. The objective is to determine the extent to which these alloys consume CO2 via the formation of carbonates or other phases, potentially supporting MgO in CO2 sequestration. In these experiments steel and Pb coupons are immersed in brines under WIPP-relevant conditions using a continuous gas flow-through system. The experimental apparatus maintains the following conditions: pO2 < 5 ppm; temperature of 26 °C; relative humidity at 78%±10%; and a range of pCO2 values (0, 350, 1500 and 3500 ppm, balance N2). Four high-ionic-strength-brines are used: Generic Weep Brine (GWB), a Na-Mg-Cl dominated brine associated with the Salado Fm.; Energy Research and Development Administration WIPP Well 6 (ERDA-6), a predominately Na-Cl brine; GWB with organic ligands (EDTA, acetate, citrate, and oxalate); and ERDA-6 with the same organic ligands. Steel coupons removed after 6 months show formation of several phases dependent on the pCO2. SEM analysis with EDS shows the presence of a green Fe (±Mg)-chlori-hydroxide phase at p

Sensitivity of technetium-99m-pyrophosphate scintigraphy in diagnosing cardiac amyloidosis

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

Falk, R.H.; Lee, V.W.; Rubinow, A.

1983-03-01

To determine the value of technetium-99m-pyrophosphate myocardial scintigraphy in the diagnosis of amyloid heart disease this procedure was prospectively performed in 20 consecutive patients with biopsy-proven primary amyloidosis. Eleven patients had echocardiographic abnormalities compatible with amyloid cardiomyopathy, 9 of whom had congestive heart failure. Diffuse myocardial pyrophosphate uptake was of equal or greater intensity than that of the ribs in 9 of the 11 patients with echocardiograms suggestive of amyloidosis, but in only 2 of the 9 with normal echocardiograms, despite abnormal electrocardiograms (p less than 0.01). Increased wall thickness measured by M-mode echocardiography correlated with myocardial pyrophosphate uptake (rmore » . 0.68, p less than 0.01). None of 10 control patients with nonamyloid, nonischemic heart disease had a strongly positive myocardial pyrophosphate uptake. Thus, myocardial technetium-99m-pyrophosphate scanning is a sensitive and specific test for the diagnosis of cardiac amyloidosis in patients with congestive heart failure of obscure origin. It does not appear to be of value for the early detection of cardiac involvement in patients with known primary amyloidosis without echocardiographic abnormalities.« less

Spectroscopic investigation of new water soluble Mn(II)(2) and Mg(II)(2) complexes for the substrate binding models of xylose/glucose isomerases.

PubMed

Patra, Ayan; Bera, Manindranath

2014-01-30

In methanol, the reaction of stoichiometric amounts of Mn(OAc)(2)·4H(2)O and the ligand H(3)hpnbpda [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in the presence of NaOH, afforded a new water soluble dinuclear manganese(II) complex, [Mn2(hpnbpda)(μ-OAc)] (1). Similarly, the reaction of Mg(OAc)(2)·4H(2)O and the ligand H3hpnbpda in the presence of NaOH, in methanol, yielded a new water soluble dinuclear magnesium(II) complex, [Mg2(hpnbpda)(μ-OAc)(H2O)2] (2). DFT calculations have been performed for the structural optimization of complexes 1 and 2. The DFT optimized structure of complex 1 shows that two manganese(II) centers are in a distorted square pyramidal geometry, whereas the DFT optimized structure of complex 2 reveals that two magnesium(II) centers adopt a six-coordinate distorted octahedral geometry. To understand the mode of substrate binding and the mechanistic details of the active site metals in xylose/glucose isomerases (XGI), we have investigated the binding interactions of biologically important monosaccharides d-glucose and d-xylose with complexes 1 and 2, in aqueous alkaline solution by a combined approach of FTIR, UV-vis, fluorescence, and (13)C NMR spectroscopic techniques. Fluorescence spectra show the binding-induced gradual decrease in emission of complexes 1 and 2 accompanied by a significant blue shift upon increasing the concentration of sugar substrates. The binding modes of d-glucose and d-xylose with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for C1 and C2 carbon atoms. Copyright © 2013 Elsevier Ltd. All rights reserved.

MgO-templated carbon as a negative electrode material for Na-ion capacitors

NASA Astrophysics Data System (ADS)

Kado, Yuya; Soneda, Yasushi

2016-12-01

In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer-Emmett-Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.

Effects of NaBF4 + NaF on the Tensile and Impact Properties of Al-Si-Mg-Fe Alloys

NASA Astrophysics Data System (ADS)

Chen, Zongning; Wang, Tongmin; Zhao, Yufei; Zheng, Yuanping; Kang, Huijun

2015-05-01

NaBF4 + NaF were found to play three roles, i.e., Fe-eliminator, grain refiner, and eutectic modifier, in treating A356 alloy with a high Fe content. The joint effects led to significant improvement in both tensile and impact properties of thus treated alloy. The multiple reactions between the NaBF4 + NaF and Al-Si-Mg-Fe system are suggested to form Fe2B, AlB2, and Na in the melt, as per thermodynamic analysis. The three are responsible for Fe removal, grain refinement, and eutectic modification, respectively. When NaBF4 and NaF are mixed in weight ratio of 1:1, an optimum addition rate is in the range between 1.0 and 2.0 wt pct for treating AlSi7Mg0.3Fe0.65 alloy, based on the results of tensile and impact tests. Excessive addition of the salt may deteriorate the mechanical properties of the alloy, basically owing to overmodification of Si and contamination of salt inclusions.

Effect of NaCl addition during diafiltration on the solubility, hydrophobicity, and disulfide bonds of 80% milk protein concentrate powder.

PubMed

Mao, X Y; Tong, P S; Gualco, S; Vink, S

2012-07-01

We investigated the surface hydrophobicity index based on different fluorescence probes [1-anilinonaphthalene-8-sulfonic acid (ANS) and 6-propionyl-2-(N,N-dimethylamino)-naphthalene (PRODAN)], free sulfhydryl and disulfide bond contents, and particle size of 80% milk protein concentrate (MPC80) powders prepared by adding various amounts of NaCl (0, 50, 100, and 150 mM) during the diafiltration process. The solubility of MPC80 powder was not strictly related to surface hydrophobicity. The MPC80 powder obtained by addition of 150 mM NaCl during diafiltration had the highest solubility but also the highest ANS-based surface hydrophobicity, the lowest PRODAN-based surface hydrophobicity, and the least aggregate formation. Intermolecular disulfide bonds caused by sulfhydryl-disulfide interchange reactions and hydrophobic interactions may be responsible for the lower solubility of the control MPC80 powder. The enhanced solubility of MPC80 powder with addition of NaCl during diafiltration may result from the modified surface hydrophobicity, the reduced intermolecular disulfide bonds, and the associated decrease in mean particle size. Addition of NaCl during the diafiltration process can modify the strength of hydrophobic interactions and sulfhydryl-disulfide interchange reactions and thereby affect protein aggregation and the solubility of MPC powders. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Experimental determination of solubilities of magnesium borates: Solubility constants of boracite [Mg 3B 7O 13Cl(cr)] and aksaite [MgB 6O 7(OH) 6 ·2H 2O(cr)

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

Xiong, Yongliang; Kirkes, Leslie Dawn; Knox, Jandi

In this work, solubility measurements regarding boracite [Mg 3B 7O 13Cl(cr)] and aksaite [MgB 6O 7(OH) 6·2H 2O(cr)] from the direction of supersaturation were conducted at 22.5 ± 0.5 °C. The equilibrium constant (log 10K 0) for boracite in terms of the following reaction, Mg 3B 7O 13Cl(cr) + 15H 2O(l) ⇌ 3Mg 2+ + 7B(OH) 4 – + Cl – + 2H + is determined as -29.49 ± 0.39 (2σ) in this study. The equilibrium constant for aksaite according to the following reaction, MgB 6O 7(OH) 6•2H 2O(cr) + 9H 2O(l) ⇌ Mg 2+ + 6B(OH) 4 – + 4H + is determined as -44.41 ± 0.41 (2σ) in this work. This work recommends a set of thermodynamic properties for aksaite at 25 °C and 1 bar as follows: ΔHmore » $$0\\atop{f}$$ =-6063.70 ± 4.85 kJ·mol -1, ΔG =-5492.55 ± 2.32 kJ·mol -1, and S 0 = 344.62 ± 1.85 J·mol -1·K -1. Among them, ΔG$$0\\atop{f}$$ is derived from the equilibrium constant for aksaite determined by this study; ΔH$$0\\atop{f}$$ is from the literature, determined by calorimetry; and S 0 is computed in the present work from ΔG$$0\\atop{f}$$ and ΔH$$0\\atop{f}$$. This investigation also recommends a set of thermodynamic properties for boracite at 25 °C and 1 bar as follows: ΔH$$0\\atop{f}$$ =-6575.02 ± 2.25 kJ·mol -1, ΔG$$0\\atop{f}$$ =-6178.35 ± 2.25 kJ·mol -1, and S 0 = 253.6 ± 0.5 J·mol -1·K -1. Among them, ΔG$$0\\atop{f}$$ is derived from the equilibrium constant for boracite determined by this study; S 0 is from the literature, determined by calorimetry; and ΔH$$0\\atop{f}$$ is computed in this work from ΔG$$0\\atop{f}$$ and S 0. The thermodynamic properties determined in this study can find applications in many fields. For instance, in the field of material science, boracite has many useful properties including ferroelectric and ferroelastic properties. The equilibrium constant of boracite determined in this work will provide guidance for economic synthesis of boracite in an aqueous medium. Similarly, in the field of nuclear waste

Experimental determination of solubilities of magnesium borates: Solubility constants of boracite [Mg 3B 7O 13Cl(cr)] and aksaite [MgB 6O 7(OH) 6 ·2H 2O(cr)

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie Dawn; Knox, Jandi; ...

2018-02-03

In this work, solubility measurements regarding boracite [Mg 3B 7O 13Cl(cr)] and aksaite [MgB 6O 7(OH) 6·2H 2O(cr)] from the direction of supersaturation were conducted at 22.5 ± 0.5 °C. The equilibrium constant (log 10K 0) for boracite in terms of the following reaction, Mg 3B 7O 13Cl(cr) + 15H 2O(l) ⇌ 3Mg 2+ + 7B(OH) 4 – + Cl – + 2H + is determined as -29.49 ± 0.39 (2σ) in this study. The equilibrium constant for aksaite according to the following reaction, MgB 6O 7(OH) 6•2H 2O(cr) + 9H 2O(l) ⇌ Mg 2+ + 6B(OH) 4 – + 4H + is determined as -44.41 ± 0.41 (2σ) in this work. This work recommends a set of thermodynamic properties for aksaite at 25 °C and 1 bar as follows: ΔHmore » $$0\\atop{f}$$ =-6063.70 ± 4.85 kJ·mol -1, ΔG =-5492.55 ± 2.32 kJ·mol -1, and S 0 = 344.62 ± 1.85 J·mol -1·K -1. Among them, ΔG$$0\\atop{f}$$ is derived from the equilibrium constant for aksaite determined by this study; ΔH$$0\\atop{f}$$ is from the literature, determined by calorimetry; and S 0 is computed in the present work from ΔG$$0\\atop{f}$$ and ΔH$$0\\atop{f}$$. This investigation also recommends a set of thermodynamic properties for boracite at 25 °C and 1 bar as follows: ΔH$$0\\atop{f}$$ =-6575.02 ± 2.25 kJ·mol -1, ΔG$$0\\atop{f}$$ =-6178.35 ± 2.25 kJ·mol -1, and S 0 = 253.6 ± 0.5 J·mol -1·K -1. Among them, ΔG$$0\\atop{f}$$ is derived from the equilibrium constant for boracite determined by this study; S 0 is from the literature, determined by calorimetry; and ΔH$$0\\atop{f}$$ is computed in this work from ΔG$$0\\atop{f}$$ and S 0. The thermodynamic properties determined in this study can find applications in many fields. For instance, in the field of material science, boracite has many useful properties including ferroelectric and ferroelastic properties. The equilibrium constant of boracite determined in this work will provide guidance for economic synthesis of boracite in an aqueous medium. Similarly, in the field of nuclear waste

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

PubMed

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

2017-05-23

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

Experimental determination of solubilities of di-calcium ethylenediaminetetraacetic acid hydrate [Ca2C10H12N2O8·7H2O(s)] in NaCl and MgCl2 solutions to high ionic strengths and its Pitzer model: Applications to geological disposal of nuclear waste and other low temperature environments

DOE PAGES

Xiong, Yongliang; Kirkes, Leslie; Westfall, Terry

2017-04-01

In this study, solubility measurements on di-calcium ethylenediaminetetraacetic acid [Ca 2C 10H 12N 2O 8(s), abbreviated as Ca 2EDTA(s)] as a function of ionic strength are conducted in NaCl solutions up to I = 5.0 mol•kg –1 and in MgCl 2 solutions up to I = 7.5 mol•kg –1, at room temperature (22.5 ± 0.5oC).

Measurement and modeling of CO₂ solubility in natural and synthetic formation brines for CO₂ sequestration.

PubMed

Zhao, Haining; Dilmore, Robert; Allen, Douglas E; Hedges, Sheila W; Soong, Yee; Lvov, Serguei N

2015-02-03

CO2 solubility data in the natural formation brine, synthetic formation brine, and synthetic NaCl+CaCl2 brine were collected at the pressures from 100 to 200 bar, temperatures from 323 to 423 K. Experimental results demonstrate that the CO2 solubility in the synthetic formation brines can be reliably represented by that in the synthetic NaCl+CaCl2 brines. We extended our previously developed model (PSUCO2) to calculate CO2 solubility in aqueous mixed-salt solution by using the additivity rule of the Setschenow coefficients of the individual ions (Na(+), Ca(2+), Mg(2+), K(+), Cl(-), and SO4(2-)). Comparisons with previously published models against the experimental data reveal a clear improvement of the proposed PSUCO2 model. Additionally, the path of the maximum gradient of the CO2 solubility contours divides the P-T diagram into two distinct regions: in Region I, the CO2 solubility in the aqueous phase decreases monotonically in response to increased temperature; in region II, the behavior of the CO2 solubility is the opposite of that in Region I as the temperature increases.

Kinetic and thermodynamic factors controlling the distribution of SO32- and Na+ in calcites and selected aragonites

USGS Publications Warehouse

Busenberg, E.; Plummer, Niel

1985-01-01

Significant amounts of SO42-, Na+, and OH- are incorporated in marine biogenic calcites. Biogenic high Mg-calcites average about 1 mole percent SO42-. Aragonites and most biogenic low Mg-calcites contain significant amounts of Na+, but very low concentrations of SO42-. The SO42- content of non-biogenic calcites and aragonites investigated was below 100 ppm. The presence of Na+ and SO42- increases the unit cell size of calcites. The solid-solutions show a solubility minimum at about 0.5 mole percent SO42- beyond which the solubility rapidly increases. The solubility product of calcites containing 3 mole percent SO42- is the same as that of aragonite. Na+ appears to have very little effect on the solubility product of calcites. The amounts of Na+ and SO42- incorporated in calcites vary as a function of the rate of crystal growth. The variation of the distribution coefficient (D) of SO42- in calcite at 25.0??C and 0.50 molal NaCl is described by the equation D = k0 + k1R where k0 and k1 are constants equal to 6.16 ?? 10-6 and 3.941 ?? 10-6, respectively, and R is the rate of crystal growth of calcite in mg??min-1??g-1 of seed. The data on Na+ are consistent with the hypothesis that a significant amount of Na+ occupies interstitial positions in the calcite structure. The distribution of Na+ follows a Freundlich isotherm and not the Berthelot-Nernst distribution law. The numerical value of the Na+ distribution coefficient in calcite is probably dependent on the number of defects in the calcite structure. The Na+ contents of calcites are not very accurate indicators of environmental salinities. ?? 1985.

PREPARATION OF ALKYL PYROPHOSPHATE EXTRACTANTS

DOEpatents

Levine, C.A.; Skiens, W.E.; Moore, G.R.

1960-08-01

A process for providing superior solvent extractants for metal recovery processes is given wherein the extractant comprises an alkyl pyrophosphoric acid ester dissolved in an organic solvent diluent. Finely divided solid P/sub 2/O/ sub 5/ is slurried in an organic solvent-diluent selected from organic solvents such as kerosene, benzene, chlorobenzene, toluene, etc. An alcohol selected from the higher alcohols having 4 to 17 carbon atoms. e.g.. hexanol-1. heptanol-3, octanol-1. 2.6-dimethyl-heptanol-4, and decanol-1, is rapidly added to the P/sub 2/O/sub 5/ slurry in the amount of about 2 moles of alcohol to 1 mole of P/sub 2/ O/sub 5/. The temperature is maintained below about 110 deg C during the course of the P/sub 2/O/sub 5/-alcohol reaction. An alkyl pyrophosphate extractant compound is formed as a consequence of the reaction process. The alkyl pyrophosphate solvent-diluent extractant phase is useful in solvent extraction metal recovery processes.

Iron(III) solubility and speciation in aqueous solutions. experimental study and modelling: part 1. hematite solubility from 60 to 300°C in NaOH-NaCl solutions and thermodynamic properties of Fe(OH) 4 -(aq)

NASA Astrophysics Data System (ADS)

Diakonov, Igor I.; Schott, Jacques; Martin, Francois; Harrichourry, Jean-Claude; Escalier, Jocelyne

1999-08-01

The solubility of natural and synthetic hematite (α-Fe 2O 3) was measured in NaOH-NaCl solutions (0.007 ≤ m(NaOH) ≤ 2.0) between 60 and 300°C at saturated water vapour pressure and under excess oxygen. Solubility constants determined in the present study and by Yishan et al. (1986) at 300°C were combined with the thermodynamic properties of hematite (Hemingway, 1990) and water (SUPCRT92, Johnson et al., 1992) to generate within the framework of the revised Helgeson-Kirkham-Flowers (HKF) model the standard partial molal thermodynamic properties at 25°C and 1 bar, and the revised HKF equations of state parameters of Fe(OH) 4 -. The extrapolated value for the Gibbs energy of formation for Fe(OH) 4 - at 25°C is -201.97 kcal/mol. Thermodynamic calculations show that Fe(OH) 4 - exhibits a chemical behaviour different from that of Ga(OH) 4 - and Al(OH) 4 -.

Short communication: Effect of storage temperature on the solubility of milk protein concentrate 80 (MPC80) treated with NaCl or KCl.

PubMed

Sikand, V; Tong, P S; Walker, J; Wang, T; Rodriguez-Saona, L E

2016-03-01

A previous study in our laboratory showed that addition of 150 mM NaCl or KCl into diafiltration water improved the solubility of freshly made milk protein concentrate 80 (MPC80). In the present study, the objectives were (1) to evaluate the solubility of NaCl- or KCl-treated MPC80 samples kept at varying temperatures and then stored for extensive periods at room temperature (21 °C ± 1 °C); and (2) to determine if MPC80 samples stored at different temperatures and protein conformation can be grouped or categorized together. Freshly manufactured MPC80 samples were untreated (control), processed with NaCl, or processed with KCl. One set of sample bags was stored at 4 °C; second and third sets of bags were kept at 25 °C and 55 °C for 1 mo (31 d) and then transferred to room temperature (21 °C ± 1 °C) storage conditions for 1 yr (365 d). Samples were tested for nitrogen solubility index (NSI) and for protein changes by Fourier-transform infrared (FTIR) spectroscopy. Analysis of variance results for NSI showed 2 significantly different groupings of MPC80 samples. The more soluble group contained samples treated with NaCl or KCl and stored at either 4 °C or 25 °C. These samples had mean NSI >97.5%. The less soluble groups contained all control samples, regardless of storage temperature, and NaCl- or KCl-treated samples stored at 55 °C. These samples had mean NSI from 39.5 to 58%. Within each of these groups (more soluble and less soluble), no significant differences in solubility were detected. Pattern recognition analysis by soft independent modeling of class analogy (SIMCA) was used to assess protein changes during storage by monitoring the amide I and amide II (1,700(-1) to 1,300 cm(-1)) regions. Dominant bands were observed at 1,385 cm(-1) for control, 1,551 cm(-1) for KCl-treated samples, and 1,694 cm(-1) for NaCl-treated samples. Moreover, SIMCA clustered the MPC80 samples stored at 4 °C separately from samples stored at 25 °C and 55 °C. This study

Simplified sample treatment for the determination of total concentrations and chemical fractionation forms of Ca, Fe, Mg and Mn in soluble coffees.

PubMed

Pohl, Pawel; Stelmach, Ewelina; Szymczycha-Madeja, Anna

2014-11-15

A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of Mg/2+/ and Ca/2+/ on urea-catalyzed phosphorylation reactions

NASA Technical Reports Server (NTRS)

Handschuk, G. J.; Lohrmann, R.; Orgel, L. E.

1973-01-01

The effect of Mg(2+) and Ca(2+) on phosphorylation reactions catalyzed by urea is investigated, showing that Mg(2+) improves markedly the yield of products containing pyrophosphate bonds. Yields of up to 25% of uridine diphosphate can be obtained with struvite at temperatures as low as 65 C.

On the calculation of solubilities via direct coexistence simulations: Investigation of NaCl aqueous solutions and Lennard-Jones binary mixtures.

PubMed

Espinosa, J R; Young, J M; Jiang, H; Gupta, D; Vega, C; Sanz, E; Debenedetti, P G; Panagiotopoulos, A Z

2016-10-21

Direct coexistence molecular dynamics simulations of NaCl solutions and Lennard-Jones binary mixtures were performed to explore the origin of reported discrepancies between solubilities obtained by direct interfacial simulations and values obtained from the chemical potentials of the crystal and solution phases. We find that the key cause of these discrepancies is the use of crystal slabs of insufficient width to eliminate finite-size effects. We observe that for NaCl crystal slabs thicker than 4 nm (in the direction perpendicular to the interface), the same solubility values are obtained from the direct coexistence and chemical potential routes, namely, 3.7 ± 0.2 molal at T = 298.15 K and p = 1 bar for the JC-SPC/E model. Such finite-size effects are absent in the Lennard-Jones system and are likely caused by surface dipoles present in the salt crystals. We confirmed that μs-long molecular dynamics runs are required to obtain reliable solubility values from direct coexistence calculations, provided that the initial solution conditions are near the equilibrium solubility values; even longer runs are needed for equilibration of significantly different concentrations. We do not observe any effects of the exposed crystal face on the solubility values or equilibration times. For both the NaCl and Lennard-Jones systems, the use of a spherical crystallite embedded in the solution leads to significantly higher apparent solubility values relative to the flat-interface direct coexistence calculations and the chemical potential values. Our results have broad implications for the determination of solubilities of molecular models of ionic systems.

Experimental study of the astrophysically important Na 23 ( α , p ) Mg 26 and Na 23 ( α , n ) Al 26 reactions

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

Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.

The 23Na(α,p) 26Mg and 23Na(α,n) 26Al reactions are important for our understanding of the 26Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α,p) 26Mg and the 23Na(α,n) 26Al reactions are in good agreementmore » with previous experiments and with statistical-model calculations. As a result, the astrophysical reaction rate of the 23Na(α,n) 26Al reaction has been reevaluated and it was found to be larger than the recommended rate.« less

Experimental study of the astrophysically important Na 23 ( α , p ) Mg 26 and Na 23 ( α , n ) Al 26 reactions

DOE PAGES

Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; ...

2016-12-19

The 23Na(α,p) 26Mg and 23Na(α,n) 26Al reactions are important for our understanding of the 26Al abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α,p) 26Mg and the 23Na(α,n) 26Al reactions are in good agreementmore » with previous experiments and with statistical-model calculations. As a result, the astrophysical reaction rate of the 23Na(α,n) 26Al reaction has been reevaluated and it was found to be larger than the recommended rate.« less

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Efficacy of a microencapsulated iron pyrophosphate-fortified fruit juice: a randomised, double-blind, placebo-controlled study in Spanish iron-deficient women.

PubMed

Blanco-Rojo, Ruth; Pérez-Granados, Ana M; Toxqui, Laura; González-Vizcayno, Carmen; Delgado, Marco A; Vaquero, M Pilar

2011-06-01

Fe-deficiency anaemia is a worldwide health problem. We studied the influence of consuming an Fe-fortified fruit juice on Fe status in menstruating women. A randomised, double-blind, placebo-controlled study of 16 weeks of duration was performed. Subjects were randomised into two groups: the P group (n 58) or the F group (n 64), and consumed, as a supplement to their usual diet, 500 ml/d of a placebo fruit juice or an Fe-fortified fruit juice, respectively. The Fe-fortified fruit juice, containing microencapsulated iron pyrophosphate, provided 18 mg Fe/d (100 % of the RDA). At baseline and monthly, dietary intake, body weight and Fe parameters were determined: total erythrocytes, haematocrit, mean corpuscular volume (MCV), red blood cell distribution width (RDW), Hb, serum Fe, serum ferritin, serum transferrin, transferrin saturation, soluble transferrin receptor (sTfR) and zinc protoporphyrin (ZnPP). The fruit juice consumption involved increased intake of carbohydrates and vitamin C, and increased BMI within normal limits. Ferritin was higher in the F group after week 4 (P < 0·05) and became 80 % higher than in the P group after week 16 (P < 0·001), and transferrin decreased in the F group compared with the P group after week 4 (P < 0·001). RDW was higher at weeks 4 and 8 in the F group compared with the P group (P < 0·05). Transferrin saturation increased after week 8, and haematocrit, MCV and Hb increased after week 12, in the F group compared with the P group. Serum Fe did not change. sTfR and ZnPP decreased in the F group at week 16 (P < 0·05). Iron pyrophosphate-fortified fruit juice improves Fe status and may be used to prevent Fe-deficiency anaemia.

Correlation of published data on the solubility of methane in H/sub 2/O-NaCl solutions

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

Coco, L.T.; Johnson, A.E. Jr.; Bebout, D.G.

1981-01-01

A new correlation of the available published data for the solubility of methane in water was developed, based on fundamental thermodynamic relationships. An empirical relationship for the salting-out coefficient of NaCl for methane solubility in water was determined as a function of temperature. Root mean square and average deviations for the new correlation, the Haas correlation, and the revised Blount equation are compared.

Phase and Physicochemical Properties Diagrams of Quaternary System Li2B4O7 + Na2B4O7 + Mg2B6O11 + H2O

NASA Astrophysics Data System (ADS)

Wang, Shi-qiang; Du, Xue-min; Jing, Yan; Guo, Ya-fei; Deng, Tian-long

2017-12-01

The phase and physicochemical properties diagrams of the quaternary system (Li2B4O7 + Na2B4O7 + Mg2B6O11) at 288.15 K and 0.1 MPa were constructed using the solubilities, densities, and refractive indices measured. In the phase diagrams of the system there are one invariant point, three univariant isothermic dissolution curves, and three crystallization regions corresponding to Li2B4O7 · 3H2O, Na2B4O7 · 10H2O, and Mg2B6O11 · 15H2O, respectively. The solution density, refractive index of the quaternary system changes regularly with the increasing of Li2B4O7 concentration. The calculated values of density and refractive index using empirical equations of the quaternary system are in good agreement with the experimental values.

Combustion of Na 2B 4O 7 + Mg + C to synthesis B 4C powders

NASA Astrophysics Data System (ADS)

Guojian, Jiang; Jiayue, Xu; Hanrui, Zhuang; Wenlan, Li

2009-09-01

Boron carbide powder was fabricated by combustion synthesis (CS) method directly from mixed powders of borax (Na 2B 4O 7), magnesium (Mg) and carbon. The adiabatic temperature of the combustion reaction of Na 2B 4O 7 + 6 Mg + C was calculated. The control of the reactions was achieved by selecting reactant composition, relative density of powder compact and gas pressure in CS reactor. The effects of these different influential factors on the composition and morphologies of combustion products were investigated. The results show that, it is advantageous for more Mg/Na 2B 4O 7 than stoichiometric ratio in Na 2B 4O 7 + Mg + C system and high atmosphere pressure in the CS reactor to increase the conversion degree of reactants to end product. The final product with the minimal impurities' content could be fabricated at appropriate relative density of powder compact. At last, boron carbide without impurities could be obtained after the acid enrichment and distilled water washing.

Reversible hydrogen storage by NaAlH4 confined within a titanium-functionalized MOF-74(Mg) nanoreactor.

PubMed

Stavila, Vitalie; Bhakta, Raghunandan K; Alam, Todd M; Majzoub, Eric H; Allendorf, Mark D

2012-11-27

We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a "nanoreactor". Confining NaAlH(4) within these pores alters the decomposition pathway by eliminating the stable intermediate Na(3)AlH(6) phase observed during bulk decomposition and proceeding directly to NaH, Al, and H(2), in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH(4)@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH(4). However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H(2) desorption is reduced from 79.5 kJ mol(-1) in bulk Ti-doped NaAlH(4) to 57.4 kJ mol(-1) for nanoconfined NaAlH(4). The structural properties of nano-NaAlH(4)@MOF-74(Mg) were probed using (23)Na and (27)Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH(4)(-) anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage.

Constraining the astrophysical 23Mg(p, γ)24Al reaction rate using the 23Na(d,p)24Na reaction

NASA Astrophysics Data System (ADS)

Bennett, E. A.; Catford, W. N.; Christian, G.; Dede, S.; Hallam, S.; Lotay, G.; Ota, S.; Saastamoinen, A.; Wilkinson, R.

2017-09-01

The 23Mg(p, γ)24Al reaction provides an escape from the Ne-Na cycle in classical novae and is therefore important in understanding nova nucleosynthesis in the A > 20 mass range. Although several resonances may contribute to the overall rate at novae temperatures, the resonance at 475 keV is thought to be dominant. The strength of this resonance has been directly measured using a radioactive 23Mg beam impinging on a windowless H2 gas target; however, recent high-precision 24Al mass measurements have called this result into question. Here we make an indirect measurement using the 23Na(d,p)24Na reaction in inverse kinematics to study the mirror state of the 475 keV resonance in 24Na. The experiment, performed at the Texas A&M Cyclotron Institute, utilized the TIARA silicon array, four HPGe detectors, and the MDM spectrometer to measure the excited states of the 24Na nucleus. Preliminary results from the experiment will be presented along with progress from the ongoing analysis.

Predictive model for growth of Clostridium perfringens during cooling of cooked beef supplemented with NaCl, sodium nitrite and sodium pyrophosphate

USDA-ARS?s Scientific Manuscript database

This paper presents a model for predicting relative growth of C. perfringens in ground beef products at different percentages of salt (0%, 1%, 2% and 3%) and nitrite (0 and 200 ppm). Included in the experiments were different levels of sodium pyrophosphate (SPP). The results of the experiments indic...

Determination of pyrophosphate and sulfate using polyhexamethylene guanidine hydrochloride-stabilized silver nanoparticles.

PubMed

Terenteva, E A; Apyari, V V; Dmitrienko, S G; Garshev, A V; Volkov, P A; Zolotov, Yu A

2018-04-01

Positively charged polyhexamethylene guanidine hydrochloride-stabilized silver nanoparticles (PHMG-AgNPs) were prepared and applied as a colorimetric probe for single-step determination of pyrophosphate and sulfate. The approach is based on the nanoparticles aggregation leading to change in their absorption spectra and color of the solution. Due to both electrostatic and steric stabilization these nanoparticles show decreased sensitivity relatively to many common anions, which allows for simple and rapid direct single-step determination of pyrophosphate and sulfate. Effects of different factors (time of interaction, pH, concentrations of anions and the nanoparticles) on aggregation of PHMG-AgNPs and analytical performance of the procedure were investigated. The method allows for the determination of pyrophosphate and sulfate in the range of 0.16-2μgmL -1 and 20-80μgmL -1 with RSD of 2-5%, respectively. The analysis can be performed using either spectrophotometry or naked-eye detection. Practical application of the method was shown by the example of pyrophosphate determination in baking powder sample. Copyright © 2017 Elsevier B.V. All rights reserved.

21 CFR 182.8223 - Calcium pyrophosphate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium pyrophosphate. 182.8223 Section 182.8223 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium...

21 CFR 182.8223 - Calcium pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium pyrophosphate. 182.8223 Section 182.8223 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8223 Calcium...

Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

PubMed

Hilty, Florentine M; Knijnenburg, Jesper T N; Teleki, Alexandra; Krumeich, Frank; Hurrell, Richard F; Pratsinis, Sotiris E; Zimmermann, Michael B

2011-01-01

Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe

A pyrophosphate-responsive gadolinium(III) MRI contrast agent.

PubMed

Surman, Andrew J; Bonnet, Célia S; Lowe, Mark P; Kenny, Gavin D; Bell, Jimmy D; Tóth, Eva; Vilar, Ramon

2011-01-03

This study shows that the relaxivity and optical properties of functionalised lanthanide-DTPA-bis-amide complexes (lanthanide=Gd(3+) and Eu(3+) , DTPA=diethylene triamine pentaacetic acid) can be successfully modulated by addition of specific anions, without direct Ln(3+) /anion coordination. Zinc(II)-dipicolylamine moieties, which are known to bind strongly to phosphates, were introduced in the amide "arms" of these ligands, and the interaction of the resulting Gd-Zn(2) complexes with a range of anions was screened by using indicator displacement assays (IDAs). Considerable selectivity for polyphosphorylated species (such as pyrophosphate and adenosine-5'-triphosphate (ATP)) over a range of other anions (including monophosphorylated anions) was apparent. In addition, we show that pyrophosphate modulates the relaxivity of the gadolinium(III) complex, this modulation being sufficiently large to be observed in imaging experiments. To establish the binding mode of the pyrophosphate and gain insight into the origin of the relaxometric modulation, a series of studies including UV/Vis and emission spectroscopy, luminescence lifetime measurements in H(2) O and D(2) O, (17) O and (31) P NMR spectroscopy and nuclear magnetic resonance dispersion (NMRD) studies were carried out. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cross Section Measurements of the Reaction 23Na(p, γ)24Mg

NASA Astrophysics Data System (ADS)

Boeltzig, Axel; Deboer, Richard James; Macon, Kevin; Wiescher, Michael; Best, Andreas; Imbriani, Gianluca; Gyürky, György; Strieder, Frank

2017-09-01

The reaction 23Na(p, γ)24Mg can provide a link from the NeNa to the MgAl cycle in stellar burning and is therefore of interest in nuclear astrophysics. To determine the reaction rates at stellar temperatures, new cross section measurements at low proton energies have been performed recently, and further experiments are underway. The current cross section data implies that the reaction rate up to temperatures of 1 GK is determined by a few narrow resonances and direct capture. Complementary to these experimental efforts at low proton energies, cross section measurements at higher energies can help to constrain the direct capture and broad resonance contributions to the cross section and reduce the uncertainty of the extrapolation towards stellar energies. In this paper we report an experiment to measure the 23Na(p, γ)24Mg cross section with a solid target setup at the St. ANA 5U accelerator at the University of Notre Dame. The experiment and the current status of data analysis will be described. This work benefited from support by the National Science Foundation under Grant No. PHY-1430152 (JINA-CEE), the Nuclear Science Laboratory (NSL), the Istituto Nazionale di Fisica Nucleare (INFN), and the Gran Sasso Science Institute (GSSI).

Reversible changes of canavalin solubility controlled by divalent cation concentration in crude sword bean extract.

PubMed

Nishizawa, Kaho; Arii, Yasuhiro

2016-12-01

Canavalin is a vicilin-class (7S) storage protein found in sword bean (Canavalia gladiata). Our previous report indicated that canavalin is precipitated by the addition of 20 mM MgCl 2 to crude sword bean extract. Here, we examined the solubility changes induced by the addition of Mg 2+ and Ca 2+ at various concentrations. Canavalin tended to be insolubilized at relatively low concentrations of MgCl 2 (< 20 mM) and solubilized at relatively high concentrations (> 20 mM). In addition, canavalin was slightly insolubilized in the presence of NaCl. Overall, the results revealed that solubility changes are reversible and depend on the concentration of divalent cations. Therefore, we suggested a reaction scheme that describes the effects of divalent cations on the solubility of canavalin, which would facilitate the study of its physiological function and the application of canavalin in the food processing industry.

Bioactive calcium pyrophosphate glasses and glass-ceramics.

PubMed

Kasuga, Toshihiro

2005-01-01

Calcium phosphate glass-based materials in the pyrophosphate region are briefly reviewed. Calcium pyrophosphate glasses can be prepared by including a small amount of TiO(2) (

Solubility and Stability of Baclofen 3 mg/mL Intrathecal Formulation and Its Compatibility With Implantable Programmable Intrathecal Infusion Systems.

PubMed

Yue, Baohua; Brendel, Ron; Lukitsch, Amelia; Prentice, Thomas; Doty, Brian

2017-06-01

Commercial baclofen formulations used with infusion pumps are available at therapeutic concentrations of 0.5-2.0 mg/mL. However, patients who receive higher daily doses of baclofen may benefit from products with greater baclofen concentrations since their refill frequency would be reduced (up to a maximum of 180 days). We evaluated baclofen solubility, baclofen 3 mg/mL intrathecal (IT) formulation stability, and chemical and physical compatibility with Medtronic SynchroMed ® II and Codman Medstream ® programmable IT infusion pumps. For solubility evaluations, baclofen powder was dissolved into isotonic saline and tested at 5°C, 25°C, and 40°C. To demonstrate drug product stability, both physical and chemical stability attributes of baclofen 3 mg/mL in prefilled syringes were evaluated over 36 months with storage at 25°C. For a simulated in-use stability (compatibility) study, a 3 mg/mL baclofen IT formulation was placed in SynchroMed II and Codman Medstream pumps at 37ºC for study durations, and evaluated at different flow rates. Pump effluent was collected at various times and analyzed by high-performance liquid chromatography for baclofen content. On completion of the in-use stability study, pumps exposed to baclofen 3 mg/mL were dissected and visually evaluated for signs of deterioration. Baclofen solubility was found to be 3.2 mg/mL at 5°C, 3.6 mg/mL at 25°C, and 3.9 mg/mL at 40°C. During the 36-month stability study of prefilled syringes stored at 25°C, baclofen content remained unchanged and no precipitation was observed. The simulated in-use pump study performed at 37ºC showed that a baclofen 3 mg/mL IT formulation was stable at different flow rates and throughout different expected residence times for both pump models. Components from both pumps exhibited no noticeable deterioration after exposure to the 3 mg/mL formulation. Baclofen 3 mg/mL IT formulation was stable during long-term storage at 25°C and remained stable under conditions matching

Titanium Pyrophosphate for Removal of Trivalent Heavy Metals and Actinides Simulated by Retention of Europium

PubMed Central

Flores-Espinosa, Rosa María; Ordoñez-Regil, Eduardo; Fernández-Valverde, Suilma Marisela

2017-01-01

This work addresses the synthesis of titanium pyrophosphate, as well as the characterization and evaluation of the sorption process of europium, for removal of trivalent heavy metals and actinides simulate. The evaluation of the surface properties of titanium pyrophosphate was carried out determining the surface roughness and surface acidity constants. The values obtained from the determination of the surface roughness of the synthesized solid indicate that the surface of the material presents itself as slightly smooth. The FITEQL program was used to fit the experimental titration curves to obtain the surface acidity constants: log⁡K+ = 3.59 ± 0.06 and log⁡K− = −3.90 ± 0.05. The results of sorption kinetics evidenced that the pseudo-order model explains the retention process of europium, in which the initial sorption velocity was 8.3 × 10−4 mg g−1 min−1 and kinetic constant was 1.8 × 10−3 g mg min−1. The maximum sorption capacity was 0.6 mg g−1. The results obtained from sorption edge showed the existence of two bidentate complexes on the surface. PMID:28785720

Direct Coexistence Methods to Determine the Solubility of Salts in Water from Numerical Simulations. Test Case NaCl.

PubMed

Manzanilla-Granados, Héctor M; Saint-Martín, Humberto; Fuentes-Azcatl, Raúl; Alejandre, José

2015-07-02

The solubility of NaCl, an equilibrium between a saturated solution of ions and a solid with a crystalline structure, was obtained from molecular dynamics simulations using the SPC/E and TIP4P-Ew water models. Four initial setups on supersaturated systems were tested on sodium chloride (NaCl) solutions to determine the equilibrium conditions and computational performance: (1) an ionic solution confined between two crystal plates of periodic NaCl, (2) a solution with all the ions initially distributed randomly, (3) a nanocrystal immersed in pure water, and (4) a nanocrystal immersed in an ionic solution. In some cases, the equilibration of the system can take several microseconds. The results from this work showed that the solubility of NaCl was the same, within simulation error, for the four setups, and in agreement with previously reported values from simulations with the setup (1). The system of a nanocrystal immersed in supersaturated solution was found to equilibrate faster than others. In agreement with laser-Doppler droplet measurements, at equilibrium with the solution the crystals in all the setups had a slight positive charge.

Indoor/outdoor of PM10 relationships and its water-soluble ions composition in selected primary schools in Malaysia

NASA Astrophysics Data System (ADS)

Mohamad, Noorlin; Latif, Mohd Talib

2013-11-01

Measurements of PM10 and water-soluble ions were carried out on indoor and outdoor PM10 (particles > 10 μm in aerodynamic diameter) aerosols sampled at selected primary schools of Kuala Lumpur (S1) and Putrajaya (S2), respectively. Samples were collected using a low volume sampler on Teflon filters. The water-soluble ions chloride (Cl-), nitrate (NO3-), sulfate (SO42-), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+) and ammonium (NH4+) was analyzed using ion chromatography. The results showed that the indoor PM10 mass concentrations in S1 and S2 were 96.6 and 69.5 μg/m3, while the outdoor PM10 mass concentrations were 80.1 and 85.2 μg/m3, respectively. This indicated that NO3- were the most dominant ions, followed by SO42-, Ca2+, K+ and Na+, while Cl-, Mg2+ and Na+ were present at low concentrations. Pearson's correlation test applied to all the data showed high correlation between SO42- and NO3-, indicating a common anthropogenic origin. In addition, the correlations between Na+ and Ca2+ indicated crustal origins that significantly contributed to human exposure.

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

NASA Astrophysics Data System (ADS)

Freyer, Daniela; Voigt, Wolfgang

2004-01-01

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

Synthetic control of manganese birnessite: Impact of crystallite size on Li, Na, and Mg based electrochemistry

DOE PAGES

Yin, Jiefu; Takeuchi, Esther S.; Takeuchi, Kenneth J.; ...

2016-08-12

We demonstrated the synthesis and characterization of Mg-birnessite (Mg xMnO 2) with different crystallite sizes, prepared though low temperature precipitation and ion exchange. The influence of crystallite size on electrochemical performance of Mg-birnessite was studied for the first time, where material with smaller crystallite size was demonstrated to have enhanced capacity and rate capability in Li ion, Na ion, and Mg ion based electrolytes. Cation diffusion using GITT type testing demonstrated the ion diffusion coefficient of Mg 2+ was ~10× lower compared with Li + and Na +. This work illustrates that tuning of inorganic materials properties can lead tomore » significant enhancement of electrochemical performance in lithium, sodium as well as magnesium based batteries for materials such as Mg-birnessite and provides a deliberate approach to improve electrochemical performance.« less

21 CFR 582.5306 - Ferric sodium pyrophosphate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

21 CFR 582.5306 - Ferric sodium pyrophosphate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

21 CFR 582.5306 - Ferric sodium pyrophosphate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

21 CFR 582.5306 - Ferric sodium pyrophosphate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ferric sodium pyrophosphate. 582.5306 Section 582.5306 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or...

Conservation of the PTEN catalytic motif in the bacterial undecaprenyl pyrophosphate phosphatase, BacA/UppP.

PubMed

Bickford, Justin S; Nick, Harry S

2013-12-01

Isoprenoid lipid carriers are essential in protein glycosylation and bacterial cell envelope biosynthesis. The enzymes involved in their metabolism (synthases, kinases and phosphatases) are therefore critical to cell viability. In this review, we focus on two broad groups of isoprenoid pyrophosphate phosphatases. One group, containing phosphatidic acid phosphatase motifs, includes the eukaryotic dolichyl pyrophosphate phosphatases and proposed recycling bacterial undecaprenol pyrophosphate phosphatases, PgpB, YbjB and YeiU/LpxT. The second group comprises the bacterial undecaprenol pyrophosphate phosphatase, BacA/UppP, responsible for initial formation of undecaprenyl phosphate, which we predict contains a tyrosine phosphate phosphatase motif resembling that of the tumour suppressor, phosphatase and tensin homologue (PTEN). Based on protein sequence alignments across species and 2D structure predictions, we propose catalytic and lipid recognition motifs unique to BacA/UppP enzymes. The verification of our proposed active-site residues would provide new strategies for the development of substrate-specific inhibitors which mimic both the lipid and pyrophosphate moieties, leading to the development of novel antimicrobial agents.

Modelling the effect of pH, sodium chloride and sodium pyrophosphate on the thermal resistance of Escherichia coli O157:H7 in ground beef

USDA-ARS?s Scientific Manuscript database

A fractional factorial design was used to assess the combined effects of four internal temperatures (55.0, 57.5, 60.0 and 62.5C) and five concentrations of sodium chloride (NaCl) (0.0, 1.5, 3.0, 4.5 and 6.0 wt/wt%) and sodium pyrophosphate (SPP) (0.0, 0.1, 0.15, 0.2 and 0.3 wt/wt%) on the heat resis...

Osteoblast response to zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate

PubMed Central

Whited, Bryce M.; Skrtic, Drago; Love, Brian J.

2006-01-01

Calcium phosphate bioceramics, such as hydroxyapatite, have long been used as bone substitutes because of their proven biocompatibility and bone binding properties in vivo. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized, which is more soluble than hydroxyapatite and allows for controlled release of calcium and phosphate ions. These ions have been postulated to increase osteoblast differentiation and mineralization in vitro. The focus of this work is to elucidate the physicochemical properties of Zr-ACP and to measure cell response to Zr-ACP in vitro using a MC3T3-E1 mouse calvarial-derived osteoprogenitor cell line. Cells were cultured in osteogenic medium and mineral was added to culture at different stages in cell maturation. Culture in the presence of Zr-ACP showed significant increases in cell proliferation, alkaline phosphatase activity (ALP), and osteopontin (OPN) synthesis, whereas collagen synthesis was unaffected. In addition, calcium and phosphate ion concentrations and medium pH were found to transiently increase with the addition of Zr-ACP, and are hypothesized to be responsible for the osteogenic effect of Zr-ACP. PMID:16278876

Proton threshold states in the Na22(p,γ)Mg23 reaction and astrophysical implications

NASA Astrophysics Data System (ADS)

Comisel, H.; Hategan, C.; Graw, G.; Wolter, H. H.

2007-04-01

Proton threshold states in Mg23 are important for the astrophysically relevant proton capture reaction Na22(p,γ)Mg23. In the indirect determination of the resonance strength of the lowest states, which were not accessible by direct methods, some of the spin-parity-assignments remained experimentally uncertain. We have investigated these states with shell model, Coulomb displacement, and Thomas-Ehrman shift calculations. From the comparison of calculated and observed properties, we relate the lowest relevant resonance state at Ex=7643 keV to an excited 3/2+ state in accordance with a recent experimental determination by Jenkins From this we deduce significantly improved values for the Na22(p,γ)Mg23 reaction rate at stellar temperatures below T9=0.1 K.

Solubility of Anhydrite (CaSO4) in NaCl-H2O Fluids at High T and P

NASA Astrophysics Data System (ADS)

Newton, R. C.; Manning, C. E.

2003-12-01

Weight losses of single crystals of a very pure natural anhydrite exposed to NaCl solutions of 0-0.3 mol fraction were measured at 600-800 \\deg C and 6-14 kbar. Experimental charges were contained in welded Pt capsules in 1.91 cm-diameter piston-cylinder apparatus with NaCl pressure medium for 5-72 hr. Measurements in initially pure H2O were made with HM, NNO, and MnO2 buffers, as well as without buffering. At 800 \\deg C and 10 kbar, CaSO4 molalities are: MnO2, 0.014 mol/kg H2O; HM, 0.017; NNO, 0.148; and unbuffered, 0.026. Variation in oxygen fugacity thus has a large effect on CaSO4 solubility, increasing with H2S/SO2 in the fluid. Unbuffered (self-buffered) charges gave solubilities much closer to HM than NNO. Melting occurred in the NNO experiment at this P and T. NaCl increases CaSO4 solubility enormously, with m(CaSO4) reaching 5.4, or 23.5 wt. %, at 800 \\deg C, 10 kbar and X(NaCl)=0.3. There is also a very large increase with temperature. Regression of all the data give: log(m-mo) = -1.533 + 0.00291T + (1.441 + 0.00016T)logX(NaCl) + 0.0413(P-10) where mo is molality in pure H2O, P is in kbar, and T is in Kelvins. The very large carrying capacity for sulfate in even mildly saline fluids at high P and T, together with the high oxygen potential generated when these solutions react with FeO in rocks to yield pyrrhotite, indicates that such fluids should be considered as principal agents in S-rich, highly oxidizing processes such as Pinatubo-type volcanic eruptions, certain deep-crustal granulite facies metamorphism, as in Bamble, Norway and Shevaroy Hills, S. India, and the anhydrite-related, oxidized Au ore deposits like Abitibi, Ontario, and Kalgoorlie, Australia.

Sensor Function for Butyrophilin 3A1 in Prenyl Pyrophosphate Stimulation of Human Vγ2Vδ2 T Cells

PubMed Central

Wang, Hong; Morita, Craig T.

2016-01-01

Vγ2Vδ2 T cells play important roles in human immunity to pathogens and in cancer immunotherapy by responding to isoprenoid metabolites, such as (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate and isopentenyl pyrophosphate. The Ig superfamily protein butyrophilin (BTN)3A1 was shown to be required for prenyl pyrophosphate stimulation. We proposed that the intracellular B30.2 domain of BTN3A1 binds prenyl pyrophosphates, resulting in a change in the extracellular BTN3A1 dimer that is detected by Vγ2Vδ2 TCRs. Such B30.2 binding was demonstrated recently. However, other investigators reported that the extracellular BTN3A1 IgV domain binds prenyl pyrophosphates, leading to the proposal that the Vγ2Vδ2 TCR recognizes the complex. To distinguish between these mechanisms, we mutagenized residues in the two binding sites and tested the mutant BTN3A1 proteins for their ability to mediate prenyl pyrophosphate stimulation of Vγ2Vδ2 T cells to proliferate and secrete TNF-α. Mutagenesis of residues in the IgV site had no effect on Vγ2Vδ2 T cell proliferation or secretion of TNF-α. In contrast, mutagenesis of residues within the basic pocket and surrounding V regions of the B30.2 domain abrogated prenyl pyrophosphate-induced proliferation. Mutations of residues making hydrogen bonds to the pyrophosphate moiety also abrogated TNF-α secretion, as did mutation of aromatic residues making contact with the alkenyl chain. Some mutations further from the B30.2 binding site also diminished stimulation, suggesting that the B30.2 domain may interact with a second protein. These findings support intracellular sensing of prenyl pyrophosphates by BTN3A1 rather than extracellular presentation. PMID:26475929

A kinetic study of struvite precipitation recycling technology with NaOH/Mg(OH)2 addition.

PubMed

Yu, Rongtai; Ren, Hongqiang; Wang, Yanru; Ding, Lili; Geng, Jingji; Xu, Ke; Zhang, Yan

2013-09-01

Struvite precipitation recycling technology is received wide attention in removal ammonium and phosphate out of wastewater. While past study focused on process efficiency, and less on kinetics. The kinetic study is essential for the design and optimization in the application of struvite precipitation recycling technology. The kinetics of struvite with NaOH/Mg(OH)2 addition were studied by thermogravimetry analysis with three rates (5, 10, 20 °C/min), using Friedman method and Ozawa-Flynn-Wall method, respectively. Degradation process of struvite with NaOH/Mg(OH)2 addition was three steps. The stripping of ammonia from struvite was mainly occurred at the first step. In the first step, the activation energy was about 70 kJ/mol, which has gradually declined as the reaction progress. By model fitting studies, the proper mechanism function for struvite decomposition process with NaOH/Mg(OH)2 addition was revealed. The mechanism function was f(α)=α(α)-(1-α)(n), a Prout-Tompkins nth order (Bna) model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Study of orthophosphate, pyrophosphate, and pyrophosphatase in saliva with reference to calculus formation and inhibition.

PubMed

Pradeep, A R; Agarwal, Esha; P, Arjun Raju; Rao, M S Narayana; Faizuddin, Mohamed

2011-03-01

A large amount of calculus may hamper the efficacy of daily oral hygiene and thereby accelerate plaque formation. Salivary concentrations of orthophosphate and pyrophosphate are important in preventing calculus formation. Activity of orthophosphate, pyrophosphate, and pyrophosphatase was studied in whole saliva in calculus-forming groups and plaque-forming groups. The material for this study consists of 60 healthy individuals (age range: 15 to 30 years; mean age: 22 years). Depending on calculus index score, individuals were divided into four groups, each of 15 patients: Group 1, calculus index score 0 to 0.6; Group 2, calculus index score 0.7 to 1.8; Group 3, calculus index score 1.9 to 3; and Group 4, plaque group where index varied from 0 to 3. The saliva was collected and biochemically analyzed for concentration of orthophosphate, pyrophosphate, and pyrophosphatase. The mean values of orthophosphate in Groups 1, 2, 3, and 4 were 0.2559, 1.3639, 1.7311, and 0.1868 mM, respectively. The mean values of pyrophosphate in Groups 1, 2, 3, and 4 were 0.3258, 0.1091, 0.0314, and 0.3860 mM, respectively. The mean values of pyrophosphatase in Groups 1, 2, 3, and 4 were 10.7937, 15.4249, 27.2900, and 7.5427 units/ml, respectively. A holistic approach toward the control of periodontal disease should include antiplaque and anticalculus agents. The results are conclusive that the components orthophosphate, pyrophosphate, and pyrophosphatase present in saliva have a very significant role to play in formation and inhibition of calculus. This study reinforces the idea of using pyrophosphate and newer bisphosphonates as potential anticalculus agents.

Solubility of aluminum and silica in Spodic horizons as affected by drying and freezing

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

Simonsson, M.; Berggren, D.; Gustafsson, J.P.

The release of toxic Al{sup 3+} is one of the most serious consequences of anthropogenic soil acidification. Therefore, the mechanisms controlling Al solubility have been a topic of intense research for more than a decade. For convenience, soil samples are often dried before storage and experimental use. However, the literature offers examples of drying that results in changes in pH, solubility of organic matter, and dissolution rates of Al. In this study, the authors examined the solubility of Al and Si in fresh soil and in soil that had been dried or deep-frozen. Five Spodosol B horizon soils were subjectedmore » to batch titrations, where portions of each soil were equilibrated with solutions with varying concentrations of acid or base added. Extractions with acid oxalate and Na pyrophosphate indicated the presence of imogolite-type materials (ITM) in three of the soils. In the other two soils most secondary solid-phase Al was associated with humic substances. Deep-freezing did not significantly change pH nor the concentration of Al or Si as compared with fresh soil. Drying, on the other hand, yielded pH increases of up to 0.3 units at a given addition of acid or base, whereas Al{sup 3+} changed only slightly, implying a higher Al solubility in all of the soils. Furthermore, dissolved silica increased by up to 200% after drying, except in a soil that almost completely lacked oxalate-extractable Si. The authors suggest that drying enhanced the dissolution of ITM by disrupting soil organic matter, thus exposing formerly coated mineral surfaces. In the soil where dissolved Si did not change with drying, it has been demonstrated that Al-humus complexes controlled Al solubility. They suggest that fissures in the organic material caused by drying may have exposed formerly occluded binding sites that had a higher Al saturation than had sites at the surface of humus particles.« less

[Characterization and optimization of the NaOH-EDTA extracts for solution 31P-NMR analysis of organic phosphorus in river sediments].

PubMed

Zhang, Wen-Qiang; Shan, Bao-Qing; Zhang, Hong; Tang, Wen-Zhong

2014-01-01

Optimization and mechanism of NaOH-EDTA extraction solutions were studied in phosphorus (P) pollution river sediments, which were Fe, Al-rich sediment, by solution 31P nuclear magnetic resonance spectroscopy (31P-NMR). Different proportions of NaOH and EDTA showed different extraction efficiency on total P (TP) and organic P (Po) in the sediment. The concentration of Po in NaOH + EDTA extract was higher than that in NaOH extract. The mechanism was that the TP and Po were released under the conditions of EDTA chelating with Fe and Al. The concentration of TP and Po were the highest in 1.00 mol x L(-1) NaOH +75 mmol x L(-1) EDTA extract and 0.25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA extract, which were 3.88 mg x g(-1) and 0.24 mg x g(-1), respectively. The extractions of Fe, Mn, Ca, Mg, Al were increasing as the EDTA increased under the same NaOH concentration. Extraction efficiency of Fe, Mn, Ca showed negative correlation with the pH of the extracting solution (P < 0.01). Exponential relationship was found between the extraction of Al and the pH of the extraction solution (P < 0.01) because of the AlO2- and EDTA-Al complex. The quality of spectra of NaOH-EDTA extract was better than that of NaOH extract. Six P species were detected in different extractions, including phosphonates, orthophosphate, pyrophosphate, orthophosphate monoesters, phospholipids and deoxyribonucleic acids. Therefore, 0. 25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA was the optimization extraction solution for Po analysis in Fe and Al-rich river sediment by 31P-NMR.

Does ascorbic acid supplementation affect iron bioavailability in rats fed micronized dispersible ferric pyrophosphate fortified fruit juice?

PubMed

Haro-Vicente, Juan Francisco; Pérez-Conesa, Darío; Rincón, Francisco; Ros, Gaspar; Martínez-Graciá, Carmen; Vidal, Maria Luisa

2008-12-01

Food iron (Fe) fortification is an adequate approach for preventing Fe-deficiency anemia. Poorly water-soluble Fe compounds have good sensory attributes but low bioavailability. The reduction of the particle size of Fe fortificants and the addition of ascorbic acid might increase the bioavailability of low-soluble compounds. The present work aims to compare the Fe absorption and bioavailability of micronized dispersible ferric pyrophosphate (MDFP) (poorly soluble) to ferrous sufate (FS) (highly soluble) added to a fruit juice in presence or absence of ascorbic acid (AA) by using the hemoglobin repletion assay in rats. After a hemoglobin depletion period, four fruit juices comprised of (1) FS, (2) MDFP, (3) FS + AA, (4) MDFP + AA were produced and administered to a different group of rats (n = 18) over 21 days. During the repletion period, Fe balance, hemoglobin regeneration efficiency (HRE), relative bioavailability (RBV) and Fe tissue content were determined in the short, medium and long term. Fe absorption and bioavailability showed no significant differences between fortifying the fruit juice with FS or MDFP. The addition of AA to the juice enhanced Fe absorption during the long-term balance study within the same Fe source. HRE and Fe utilization increased after AA addition in both FS and MDFP groups in every period. Fe absorption and bioavailability from MDFP were comparable to FS added to a fruit juice in rats. Further, the addition of AA enhanced Fe absorption in the long term, as well as Fe bioavailability throughout the repletion period regardless of the Fe source employed.

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

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

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

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

Single- and repeated-dose oral toxicity studies of citicoline free-base (choline cytidine 5'-pyrophosphate) in Sprague-Dawley rats.

PubMed

Schauss, A G; Somfai-Relle, S; Financsek, I; Glavits, R; Parent, S C; Endres, J R; Varga, T; Szücs, Z; Clewell, A

2009-01-01

The dietary supplement Citicoline free-base (choline cytidine 5'-pyrophosphate) was toxicologically evaluated in Sprague-Dawley rats using oral gavage. In an acute 14-day study, 2000 mg/kg was well tolerated. In a 90-day study, 100, 350, and 1000 mg/kg/day doses resulted in no mortality. In males, slight significant increases in serum creatinine (350 and 1000 mg/kg/day), and decreases in urine volume (all treated groups) were observed. In females, slight significant increases in total white blood cell and absolute lymphocyte counts (1000 mg/kg/day), and blood urea nitrogen (BUN) (100 and 350, but not 1000 mg/kg/day) were noted. A dose-related increase in renal tubular mineralization, without degenerative or inflammatory reaction, was found in females (all treated groups) and two males (1000 mg/kg/day). Renal mineralization in rats (especially females) is influenced by calcium:phosphorus ratios in the diet. A high level of citicoline consumption resulted in increased phosphorus intake in the rats, and likely explains this result.

Hygroscopic Properties of Internally Mixed Particles Composed of NaCl and Water-Soluble Organic Acids

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

Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei V.

Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy and X-ray elemental microanalysis.Hygroscopic properties of inte rnally mixed NaCl and organic acid particles were distinctly differentmore » from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of Na-malonate and Na-glutarate salts resulted by HCl evaporation from dehydrating particles.« less

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

PubMed

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

1978-05-01

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

Distinguishing erosive osteoarthritis and calcium pyrophosphate deposition disease.

PubMed

Rothschild, Bruce M

2013-04-18

Erosive osteoarthritis is a term utilized to describe a specific inflammatory condition of the interphalangeal and first carpal metacarpal joints of the hands. The term has become a part of medical philosophical semantics and paradigms, but the issue is actually more complicated. Even the term osteoarthritis (non-erosive) has been controversial, with some suggesting osteoarthrosis to be more appropriate in view of the perspective that it is a non-inflammatory process undeserving of the "itis" suffix. The term "erosion" has also been a source of confusion in osteoarthritis, as it has been used to describe cartilage, not bone lesions. Inflammation in individuals with osteoarthritis actually appears to be related to complicating phenomena, such as calcium pyrophosphate and hydroxyapatite crystal deposition producing arthritis. Erosive osteoarthritis is the contentious term. It is used to describe a specific form of joint damage to specific joints. The damage has been termed erosions and the distribution of the damage is to the interphalangeal joints of the hand and first carpal metacarpal joint. Inflammation is recognized by joint redness and warmth, while X-rays reveal alteration of the articular surfaces, producing a smudged appearance. This ill-defined, joint damage has a crumbling appearance and is quite distinct from the sharply defined erosions of rheumatoid arthritis and spondyloarthropathy. The appearance is identical to those found with calcium pyrophosphate deposition disease, both in character and their unique responsiveness to hydroxychloroquine treatment. Low doses of the latter often resolve symptoms within weeks, in contrast to higher doses and the months required for response in other forms of inflammatory arthritis. Reconsidering erosive osteoarthritis as a form of calcium pyrophosphate deposition disease guides physicians to more effective therapeutic intervention.

Redox Additive-Improved Electrochemically and Structurally Robust Binder-Free Nickel Pyrophosphate Nanorods as Superior Cathode for Hybrid Supercapacitors.

PubMed

Sankar, Kalimuthu Vijaya; Seo, Youngho; Lee, Su Chan; Chan Jun, Seong

2018-03-07

For several decades, one of the great challenges for constructing a high-energy supercapacitor has been designing electrode materials with high performance. Herein, we report for the first time to our knowledge a novel hybrid supercapacitor composed of battery-type nickel pyrophosphate one-dimensional (1D) nanorods and capacitive-type N-doped reduced graphene oxide as the cathode and anode, respectively, in an aqueous redox-added electrolyte. More importantly, ex situ microscopic images of the nickel pyrophosphate 1D nanorods revealed that the presence of the battery-type redox additive enhanced the charge storage capacity and cycling life as a result of the microstructure stability. The nickel pyrophosphate 1D nanorods exhibited their maximum specific capacitance (8120 mF cm -2 at 5 mV s -1 ) and energy density (0.22 mWh cm -2 at a power density of 1.375 mW cm -2 ) in 1 M KOH + 75 mg K 3 [Fe(CN) 6 ] electrolyte. On the other side, the N-doped reduced graphene oxide delivered an excellent electrochemical performance, demonstrating that it was an appropriate anode. A hybrid supercapacitor showed a high specific capacitance (224 F g -1 at a current density of 1 A g -1 ) and high energy density (70 Wh kg -1 at a power density of 750 W kg -1 ), as well as a long cycle life (a Coulombic efficiency of 96% over 5000 cycles), which was a higher performance than most of those in recent reports. Our results suggested that the materials and redox additive in this novel design hold great promise for potential applications in a next-generation hybrid supercapacitor.

Enhancing anaerobic digestion of waste activated sludge by the combined use of NaOH and Mg(OH)2: Performance evaluation and mechanism study.

PubMed

Huang, Cheng; Lai, Jia; Sun, Xiuyun; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

2016-11-01

In this study, the combination treatment of NaOH and Mg(OH)2 was applied to anaerobic digestion of waste activated sludge (WAS) for simultaneously enhancement of volatile fatty acids (VFAs) production, nutrients removal and sludge dewaterability. The maximum VFAs production (461mg COD/g VSS) was obtained at the NaOH/Mg(OH)2 ratio of 75:25, which was much higher than that of the blank or sole NaOH. Moreover, nutrients removal and sludge dewaterability were improved by the combined using of NaOH and Mg(OH)2. Mechanism investigations revealed that the presence of Mg(OH)2 could maintain alkaline environment, which contributed to inhibit the activity of methanogens. Also, the bridging between Mg(2+) and extracellular polymeric substances (EPS) plays an important role in the solubilization and dewatering of sludge. High-throughput sequencing analysis demonstrated that the abundance of bacteria involved in sludge hydrolysis and VFAs accumulation was greatly enriched with the mixtures of NaOH and Mg(OH)2. Copyright © 2016 Elsevier Ltd. All rights reserved.

The 21 Na (p,γ) 22 Mg reaction from Ec.m. =200 to 1103 keV in novae and x-ray bursts

NASA Astrophysics Data System (ADS)

D'Auria, J. M.; Azuma, R. E.; Bishop, S.; Buchmann, L.; Chatterjee, M. L.; Chen, A. A.; Engel, S.; Gigliotti, D.; Greife, U.; Hunter, D.; Hussein, A.; Hutcheon, D.; Jewett, C. C.; José, J.; King, J. D.; Laird, A. M.; Lamey, M.; Lewis, R.; Liu, W.; Olin, A.; Ottewell, D.; Parker, P.; Rogers, J.; Ruiz, C.; Trinczek, M.; Wrede, C.

2004-06-01

The long-lived radioactive nuclide 22 Na ( t1/2 =2.6 yr) is an astronomical observable for understanding the physical processes of oxygen-neon novae. Yields of 22Na in these events are sensitive to the unknown total rate of the 21 Na (p,γ) 22 Mg reaction. Using a high intensity 21 Na beam at the TRIUMF-ISAC facility, the strengths of seven resonances in 22 Mg , of potential astrophysical importance, have been directly measured at center of mass energies from Ec.m. =200 to 1103 keV . We report the results obtained for these resonances and their respective contributions to the 21 Na (p,γ) 22 Mg rate in novae and x-ray bursts, and their impact on 22 Na production in novae.

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

PubMed

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

2012-04-01

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

Human recombinant soluble guanylyl cyclase: expression, purification, and regulation

NASA Technical Reports Server (NTRS)

Lee, Y. C.; Martin, E.; Murad, F.

2000-01-01

The alpha1- and beta1-subunits of human soluble guanylate cyclase (sGC) were coexpressed in the Sf9 cells/baculovirus system. In addition to the native enzyme, constructs with hexahistidine tag at the amino and carboxyl termini of each subunit were coexpressed. This permitted the rapid and efficient purification of active recombinant enzyme on a nickel-affinity column. The enzyme has one heme per heterodimer and was readily activated with the NO donor sodium nitroprusside or 3-(5'-hydroxymethyl-2'furyl)-1-benzyl-indazole (YC-1). Sodium nitroprusside and YC-1 treatment potentiated each other in combination and demonstrated a remarkable 2,200-fold stimulation of the human recombinant sGC. The effects were inhibited with 1H-(1,2, 4)oxadiazole(4,3-a)quinoxalin-1one (ODQ). The kinetics of the recombinant enzyme with respect to GTP was examined. The products of the reaction, cGMP and pyrophosphate, inhibited the enzyme. The extent of inhibition by cGMP depended on the activation state of the enzyme, whereas inhibition by pyrophosphate was not affected by the enzyme state. Both reaction products displayed independent binding and cooperativity with respect to enzyme inhibition. The expression of large quantities of active enzyme will facilitate structural characterization of the protein.

LEFPS1, a Tomato Farnesyl Pyrophosphate Gene Highly Expressed during Early Fruit Development1

PubMed Central

Gaffe, Joel; Bru, Jean-Philippe; Causse, Mathilde; Vidal, Alain; Stamitti-Bert, Linda; Carde, Jean-Pierre; Gallusci, Philippe

2000-01-01

Farnesyl pyrophosphate synthase (FPS) catalyzes the synthesis of farnesyl pyrophosphate, a key intermediate in sterol and sesquiterpene biosynthesis. Using a polymerase chain reaction-based approach, we have characterized LeFPS1, a tomato (Lycoperscion esculentum cv Wva 106) fruit cDNA, which encodes a functional FPS. We demonstrate that tomato FPSs are encoded by a small multigenic family with genes located on chromosomes 10 and 12. Consistent with farnesyl pyrophosphate requirement in sterol biosynthesis, FPS genes are ubiquitously expressed in tomato plants. Using an LeFPS1 specific probe, we show that the corresponding gene can account for most of FPS mRNA in most plant organs, but not during young seedling development, indicating a differential regulation of FPS genes in tomato. FPS gene expression is also under strict developmental control: FPS mRNA was mainly abundant in young organs and decreased as organs matured with the exception of fruits that presented a biphasic accumulation pattern. In this latter case in situ hybridization studies have shown that FPS mRNA is similarly abundant in all tissues of young fruit. Taken together our results suggest that several FPS isoforms are involved in tomato farnesyl pyrophosphate metabolism and that FPS genes are mostly expressed in relation to cell division and enlargement. PMID:10938353

Distinguishing erosive osteoarthritis and calcium pyrophosphate deposition disease

PubMed Central

Rothschild, Bruce M

2013-01-01

Erosive osteoarthritis is a term utilized to describe a specific inflammatory condition of the interphalangeal and first carpal metacarpal joints of the hands. The term has become a part of medical philosophical semantics and paradigms, but the issue is actually more complicated. Even the term osteoarthritis (non-erosive) has been controversial, with some suggesting osteoarthrosis to be more appropriate in view of the perspective that it is a non-inflammatory process undeserving of the “itis” suffix. The term “erosion” has also been a source of confusion in osteoarthritis, as it has been used to describe cartilage, not bone lesions. Inflammation in individuals with osteoarthritis actually appears to be related to complicating phenomena, such as calcium pyrophosphate and hydroxyapatite crystal deposition producing arthritis. Erosive osteoarthritis is the contentious term. It is used to describe a specific form of joint damage to specific joints. The damage has been termed erosions and the distribution of the damage is to the interphalangeal joints of the hand and first carpal metacarpal joint. Inflammation is recognized by joint redness and warmth, while X-rays reveal alteration of the articular surfaces, producing a smudged appearance. This ill-defined, joint damage has a crumbling appearance and is quite distinct from the sharply defined erosions of rheumatoid arthritis and spondyloarthropathy. The appearance is identical to those found with calcium pyrophosphate deposition disease, both in character and their unique responsiveness to hydroxychloroquine treatment. Low doses of the latter often resolve symptoms within weeks, in contrast to higher doses and the months required for response in other forms of inflammatory arthritis. Reconsidering erosive osteoarthritis as a form of calcium pyrophosphate deposition disease guides physicians to more effective therapeutic intervention. PMID:23610748

The selectivity of water-based pyrophosphate recognition is tuned by metal substitution in dimetallic receptors.

PubMed

Svane, Simon; Kjeldsen, Frank; McKee, Vickie; McKenzie, Christine J

2015-07-14

The three dimetallic compounds [Ga2(bpbp)(OH)2(H2O)2](ClO4)3, [In2(bpbp)(CH3CO2)2](ClO4)3 and [Zn2(bpbp)(HCO2)2](ClO4) (bpbp(-) = 2,6-bis((N,N'-bis(2-picolyl)amino)methyl)-4-tertbutylphenolate) were evaluated as stable solid state precursors for reactive solution state receptors to use for the recognition of the biologically important anion pyrophosphate in water at neutral pH. Indicator displacement assays using in situ generated complex-pyrocatechol violet adducts, {M2(bpbp)(HxPV)}(n+) M = Ga(3+), In(3+), Zn(2+), were tested for selectivity in their reactions with a series of common anions: pyrophosphate, phosphate, ATP, arsenate, nitrate, perchlorate, chloride, sulfate, formate, carbonate and acetate. The receptor employing Ga(3+) showed a slow but visually detectable response (blue to yellow) in the presence of one equivalent of pyrophosphate but no response to any other anion, even when they were present in much higher concentrations. The systems based on In(3+) or Zn(2+) show less selectivity in accord with visibly discernible responses to several of the anions. These results demonstrate a facile method for increasing anion selectivity without modification of an organic dinucleating ligand scaffold. The comfortable supramolecular recognition of pyrophosphate by the dimetallic complexes is demonstrated by the single crystal X-ray structure of [Ga2(bpbp)(HP2O7)](ClO4)2 in which the pyrophosphate is coordinated to the two gallium ions via four of its oxygen atoms.

Label-Free Pyrophosphate Recognition with Functionalized Asymmetric Nanopores.

PubMed

Ali, Mubarak; Ahmed, Ishtiaq; Ramirez, Patricio; Nasir, Saima; Niemeyer, Christof M; Mafe, Salvador; Ensinger, Wolfgang

2016-04-01

The label-free detection of pyrophosphate (PPi) anions with a nanofluidic sensing device based on asymmetric nanopores is demonstrated. The pore surface is functionalized with zinc complexes based on two di(2-picolyl)amine [bis(DPA)] moieties using carbodiimide coupling chemistry. The complexation of zinc (Zn(2+) ) ion is achieved by exposing the modified pore to a solution of zinc chloride to form bis(Zn(2+) -DPA) complexes. The chemical functionalization is demonstrated by recording the changes in the observed current-voltage (I-V) curves before and after pore modification. The bis(Zn(2+) -DPA) complexes on the pore walls serve as recognition sites for pyrophosphate anion. The experimental results show that the proposed nanofluidic sensor has the ability to sense picomolar concentrations of PPi anion in the surrounding environment. On the contrary, it does not respond to other phosphate anions, including monohydrogen phosphate, dihydrogen phosphate, adenosine monophosphate, adenosine diphosphate, and adenosine triphosphate. The experimental results are described theoretically by using a model based on the Poisson-Nernst-Planck equations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2015-03-28

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

Effect of heavy metals on pH buffering capacity and solubility of Ca, Mg, K, and P in non-spiked and heavy metal-spiked soils.

PubMed

Najafi, Sarvenaz; Jalali, Mohsen

2016-06-01

In many parts of the world, soil acidification and heavy metal contamination has become a serious concern due to the adverse effects on chemical properties of soil and crop yield. The aim of this study was to investigate the effect of pH (in the range of 1 to 3 units above and below the native pH of soils) on calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) solubility in non-spiked and heavy metal-spiked soil samples. Spiked samples were prepared by cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) as chloride salts and incubating soils for 40 days. The pH buffering capacity (pHBC) of each sample was determined by plotting the amount of H(+) or OH(-) added (mmol kg(-1)) versus the related pH value. The pHBC of soils ranged from 47.1 to 1302.5 mmol kg(-1) for non-spiked samples and from 45.0 to 1187.4 mmol kg(-1) for spiked soil samples. The pHBC values were higher in soil 2 (non-spiked and spiked) which had higher calcium carbonate content. The results indicated the presence of heavy metals in soils generally decreased the solution pH and pHBC values in spiked samples. In general, solubility of Ca, Mg, and K decreased with increasing equilibrium pH of non-spiked and spiked soil samples. In the case of P, increasing the pH to about 7, decreased the solubility in all soils but further increase of pH from 7, enhanced P solubility. The solubility trends and values for Ca, Mg, and K did not differed significantly in non-spiked and spiked samples. But in the case of P, a reduction in solubility was observed in heavy metal-spiked soils. The information obtained in this study can be useful to make better estimation of the effects of soil pollutants on anion and cation solubility from agricultural and environmental viewpoints.

Sensitivity of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) to MgSO4 and Na2SO4

NASA Astrophysics Data System (ADS)

Vellemu, E. C.; Mensah, P. K.; Griffin, N. J.; Odume, O. N.

2017-08-01

Acid mine drainage (AMD) continues to deteriorate water quality in freshwater ecosystems. Sulphates, a major salt component in AMD, can exacerbate AMD effects in freshwater because salts are toxic to aquatic life in high concentrations. Sulphates are predominant in South African AMD impacted freshwater ecosystems. In this study, the sensitivity of nymphs of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) was investigated by exposing the organisms to magnesium sulphate (MgSO4) and sodium sulphate (Na2SO4) as models of mining salinisation in short-term (96 h) and long-term (240 h) in static system tests. Short-term and long-term lethal concentrations of each salt were estimated using regression analyses. The results indicated that A. auriculata was more sensitive to MgSO4 (LC50 = 3.81 g/L) than Na2SO4 (LC50 = 8.78 g/L) after short-term exposures. However, this species became sensitive to Na2SO4 (LC10 = 0.19 g/L) but tolerant to MgSO4 (LC10 = 0.35 g/L) after long-term exposures. These results suggest that the 0.25 g/L sulphate compliance limit for South Africa is inadequate to protect A. auriculata from Na2SO4 toxicity in the long-term, yet it overprotects this species from MgSO4 exposures in the short-term. The findings of this study are an important major step in understanding the ecological effects of AMD to aquatic life.

SEPARATION OF PLUTONIUM IONS FROM SOLUTION BY ADSORPTION ON ZIRCONIUM PYROPHOSPHATE

DOEpatents

Stoughton, R.W.

1961-01-31

A method is given for separating plutonium in its reduced, phosphate- insoluble state from other substances. It involves contacting a solution containing the plutonium with granular zirconium pyrophosphate.

The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the Na-Ca-Cl-SO 4-H 2O system, to high temperature and concentration

NASA Astrophysics Data System (ADS)

Møller, Nancy

1988-04-01

This paper describes a chemical equilibrium model for the Na-Ca-Cl-SO 4-H 2O system which calculates solubilities from 25°C to 250°C and from zero to high concentration ( I ~ 18. m) within experimental uncertainty. The concentration and temperature dependence of the model were established by fitting available activity (solubility, osmotic and emf) data. A single ion complex, CaSO 04, which increases in strength with temperature, is included explicitly in the model. The validation of model accuracy by comparison to laboratory and field solubility data is included. Applications of the model are also given. Phase diagrams constructed for the Na-Ca-Cl-SO 4-H 2O system and predicted solubilities of anhydrite and hemihydrate in concentrated seawater at high temperature are in very good agreement with the data. Calculations of the temperature of gypsum-anhydrite coexistence as a function of water activity are compared to reported values, and are used to estimate the composition-temperature relation for gypsum-anhydrite transition in a natural brine evaporation. A preliminary model for barite solubility in sodium chloride solutions at high temperature (100°C to 250°C), based on this parameterization of the CaSO 4-NaCl-H 2O system, gives good agreement with the data.

Effect of cyclodextrin complexation on the aqueous solubility and solubility/dose ratio of praziquantel.

PubMed

Maragos, Stratos; Archontaki, Helen; Macheras, Panos; Valsami, Georgia

2009-01-01

Praziquantel (PZQ), the primary drug of choice in the treatment of schistosomiasis, is a highly lipophilic drug that possesses high permeability and low aqueous solubility and is, therefore, classified as a Class II drug according to the Biopharmaceutics Classification System (BCS). In this work, beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were used in order to determine whether increasing the aqueous solubility of a drug by complexation with CDs, a BCS-Class II compound like PZQ could behave as BCS-Class I (highly soluble/highly permeable) drug. Phase solubility and the kneading and lyophilization techniques were used for inclusion complex preparation; solubility was determined by UV spectroscopy. The ability of the water soluble polymer polyvinylpyrolidone (PVP) to increase the complexation and solubilization efficiency of beta-CD and HP-beta-CD for PZQ was examined. Results showed significant improvement of PZQ solubility in the presence of both cyclodextrins but no additional effect in the presence of PVP. The solubility/dose ratios values of PZQ-cyclodextrin complexes calculated considering the low (150 mg) and the high dose (600 mg) of PZQ, used in practice, indicate that PZQ complexation with CDs may result in drug dosage forms that would behave as a BCS-Class I depending on the administered dose.

Properties of complexes formed by Na(+), Mg(2+), and Fe(2+) binding with benzene molecules.

PubMed

Kolakkandy, Sujitha; Pratihar, Subha; Aquino, Adelia J A; Wang, Hai; Hase, William L

2014-10-09

A theoretical investigation was performed to study cation-π interactions in complexes of benzene (Bz) with cations, that is, M(z+)(Bz)n for M(z+) = Na(+), Mg(2+), Fe(2+) and n = 1-3, using MP2 theory with the 6-31+G* and 6-311++G** basis sets and the DFT/(B3LYP and B3LYP-D)/6-311++G** methods. Binding energies and structures of the complexes are reported. The splitting between the quintet and single states of the Fe(2+) complexes was found to depend on the number of benzene molecules in the complex and the complex's structure. All of the M(z+)(Bz) complexes prefer a half-sandwich geometry. A geometry with the cation sandwiched between the two benzene rings was found for the M(z+)(Bz)2 complexes, with the benzene rings either in an eclipsed or staggered conformation. An approximate cyclic structure, with the cation at its center, was found for three benzene molecules interacting with the cation. The cation-benzene binding energy is substantial and equal to 22, 108, and 151 kcal/mol for the Na(+)(Bz), Mg(2+)(Bz), and Fe(2+)(Bz) complexes, respectively. The strength of the interaction of the cation with an individual benzene molecule decreases as the number of benzene molecules bound to the cation increases; for example, it is 108 kcal/mol for Mg(2+)(Bz), but only 71 kcal/mol for Mg(2+)(Bz)3. There is a range of values for the M(z+)(Bz)n intermolecular vibrational frequencies; for example, they are ∼230-360 and ∼10-330 cm(-1) for the Mg(2+)(Bz) and Mg(2+)(Bz)3 complexes, respectively. Binding of the cation to benzene both red and blue shifts the benzene vibrational frequencies. This shifting is larger for the Mg(2+) and Fe(2+) complexes, as compared to those for Na(+), as a result of the former's stronger cation-benzene binding. The present study is an initial step to understand the possible importance of cation-π interactions for polycyclic aromatic hydrocarbon aggregation processes during soot formation.

Solubility of metal oxides in molten equimolar KBr-NaBr mixture at 973 K

NASA Astrophysics Data System (ADS)

Cherginets, V. L.; Rebrova, T. P.; Naumenko, V. A.

2014-09-01

Solubility products (p K s,MO, molality) are measured by potentiometric titration with a Pt(O2)|ZrO2(Y2O3) oxygen electrode in the molten KBr-NaBr equimolar mixture at 973 K for the following oxides: CaO (5.00 ± 0.3), MnO (7.85 ± 0.3), NiO (9.72 ± 0.04), PbO (5.20 ± 0.3), and SrO (3.81 ± 0.3). The correlation between p K s,MeO and the polarization of the corresponding cations by Goldschmidt is obtained.

Mineral contents and their solubility on calcium carbonat calcite nanocrystals from cockle shell powder (Anadara granosa Linn)

NASA Astrophysics Data System (ADS)

Widyastuti, S.; Pramushinta, I. A.

2018-03-01

Prepared and characterized calcium carbonat calcite nanocrystals improves solubility. Calcium carbonat calcite nanocrystals were synthesized using precipitation method from the waste of blood clam cockle shells (Anadara granosa Linn). This study was conducted to analyze mineral composition of nanocrystals calcium carbonat calcite cockle (Anadara granosa) shell for calcium fortification of food applications and to evaluate the solubilities of Calsium and Phospor. The sample of nanocrystals from cockle shells was evaluated to determine the content of 11 macro-and micro-elements. These elements are Calcium (Ca), Magnesium (Mg), Sodium (Na), Phosphorus (P), Potassium (K), Ferrum (Fe), Copper (Cu), Nickel (Ni), Zink (Zn), Boron (B) and Silica (Si)). Cockleshell powders were found to contain toxic elements below detectable levels. The solubilities of Calcium and Phospor were p<0.05.

Thermodynamic Study of Solid-Liquid Equilibrium in NaCl-NaBr-H2O System at 288.15 K

NASA Astrophysics Data System (ADS)

Li, Dan; Meng, Ling-zong; Deng, Tian-long; Guo, Ya-fei; Fu, Qing-Tao

2018-06-01

The solubility data, composition of the solid solution and refractive indices of the NaCl-NaBr-H2O system at 288.15 K were studied with the isothermal equilibrium dissolution method. The solubility diagram and refractive index diagram of this system were plotted at 288.15 K. The solubility diagram consists of two crystallization zones for solid solution Na(Cl,Br) · 2H2O and Na(Cl,Br), one invariant points cosaturated with two solid solution and two univariant solubility isothermal curves. On the basis of Pitzer and Harvie-Weare (HW) chemical models, the composition equations and solubility equilibrium constant equations of the solid solutions at 288.15 K were acquired using the solubility data, the composition of solid solutions, and binary Pitzer parameters. The solubilities calculated using the new method combining the equations are in good agreement with the experimental data.

Study of Np(V) Sorption by Ionic Exchange on Na, K, Ca and Mg-Montmorillonite

NASA Astrophysics Data System (ADS)

Benedicto, A.; Begg, J.; Zhao, P.; Kersting, A. B.; Zavarin, M.

2012-12-01

The transport behavior of actinides in soil and ground water are highly influenced by clay minerals due to their ubiquity in the environment, reactivity and colloidal properties. Neptunium(V) has been introduced in the environment as a result of nuclear weapons testing [e.g. 1, 2] and is a radionuclide of potential interest for safety assessment of high level radioactive waste disposal because its long half-life and high toxicity [3]. Surface complexation and ionic exchange have been identified as Np(V) sorption mechanisms onto montmorillonite. At pH below 5, Np(V) sorption is mainly attributed to ionic exchange. This study examines Np(V) ion exchange on Na, K, Ca and Mg forms of montmorillonite. Experiments were carried out using 237Np concentrations between 2 x 10-8 M and 5 x 10-6 M at three different ionic strengths 0.1, 0.01 and 0.001M. The pH was maintained at 4.5. Np(V) sorption to montmorillonite homoionized with monovalent cations (Na and K) demonstrated a markedly different behavior to that observed for montmorillonite homoionized with divalent cations (Ca and Mg). Np sorption to Na and K-montmorillonite was greater than Np sorption to Ca and Mg-montmorillonite. Isotherms with Na and K-montmorillonite showed a strong dependence on ionic strength: the percentage of Np adsorbed was near zero at 0.1M ionic strength, but increased to 30% at 0.001 M ionic strength. This suggests ionic exchange is the main Np adsorption mechanism under the experimental conditions investigated. Dependence on ionic strength was not observed in the Np sorption isotherms for Ca and Mg-montmorillonite indicating a low exchange capacity between Np and divalent cations. Modeling of the sorption experimental data will allow determination of the Na+↔NpO2+ and K+↔NpO2+ ionic exchange constants on montmorillonite. References: [1] A. R. Felmy; K. J. Cantrell; S. D. Conradson, Phys. Chem. Earth 2010, 35, 292-297 [2] D. K. Smith; D. L. Finnegan; S. M. Bowen, J. Environ. Radioact. 2003, 67

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

NASA Astrophysics Data System (ADS)

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

2018-04-01

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

Novel high/low solubility classification methods for new molecular entities.

PubMed

Dave, Rutwij A; Morris, Marilyn E

2016-09-10

This research describes a rapid solubility classification approach that could be used in the discovery and development of new molecular entities. Compounds (N=635) were divided into two groups based on information available in the literature: high solubility (BDDCS/BCS 1/3) and low solubility (BDDCS/BCS 2/4). We established decision rules for determining solubility classes using measured log solubility in molar units (MLogSM) or measured solubility (MSol) in mg/ml units. ROC curve analysis was applied to determine statistically significant threshold values of MSol and MLogSM. Results indicated that NMEs with MLogSM>-3.05 or MSol>0.30mg/mL will have ≥85% probability of being highly soluble and new molecular entities with MLogSM≤-3.05 or MSol≤0.30mg/mL will have ≥85% probability of being poorly soluble. When comparing solubility classification using the threshold values of MLogSM or MSol with BDDCS, we were able to correctly classify 85% of compounds. We also evaluated solubility classification of an independent set of 108 orally administered drugs using MSol (0.3mg/mL) and our method correctly classified 81% and 95% of compounds into high and low solubility classes, respectively. The high/low solubility classification using MLogSM or MSol is novel and independent of traditionally used dose number criteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2.

PubMed

Maitra, Urmimala; House, Robert A; Somerville, James W; Tapia-Ruiz, Nuria; Lozano, Juan G; Guerrini, Niccoló; Hao, Rong; Luo, Kun; Jin, Liyu; Pérez-Osorio, Miguel A; Massel, Felix; Pickup, David M; Ramos, Silvia; Lu, Xingye; McNally, Daniel E; Chadwick, Alan V; Giustino, Feliciano; Schmitt, Thorsten; Duda, Laurent C; Roberts, Matthew R; Bruce, Peter G

2018-03-01

The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li + -O(2p)-Li + interactions). Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg 2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg 2+ remains in Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 , which stabilizes oxygen.

Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2

NASA Astrophysics Data System (ADS)

Maitra, Urmimala; House, Robert A.; Somerville, James W.; Tapia-Ruiz, Nuria; Lozano, Juan G.; Guerrini, Niccoló; Hao, Rong; Luo, Kun; Jin, Liyu; Pérez-Osorio, Miguel A.; Massel, Felix; Pickup, David M.; Ramos, Silvia; Lu, Xingye; McNally, Daniel E.; Chadwick, Alan V.; Giustino, Feliciano; Schmitt, Thorsten; Duda, Laurent C.; Roberts, Matthew R.; Bruce, Peter G.

2018-03-01

The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li+-O(2p)-Li+ interactions). Na2/3[Mg0.28Mn0.72]O2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na2/3[Mg0.28Mn0.72]O2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg2+ remains in Na2/3[Mg0.28Mn0.72]O2, which stabilizes oxygen.

Measurement of the 21Na(p,{gamma})22Mg Reaction with the Dragon Facility at TRIUMF-ISAC

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

Chen, A.A.; Bishop, S.; D'Auria, J.M.

2003-08-26

The DRAGON recoil separator facility, designed to measure the rates of radiative proton and alpha capture reactions important for nuclear astrophysics, is now operational at the TRIUMF-ISAC radioactive beam facility in Vancouver, Canada. We report on first measurements of the 21Na(p,{gamma})22Mg reaction rate with radioactive beams of 21Na.

Proton threshold states in the {sup 22}Na(p,{gamma}){sup 23}Mg reaction and astrophysical implications

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

Comisel, H.; Hategan, C.; Graw, G.

Proton threshold states in {sup 23}Mg are important for the astrophysically relevant proton capture reaction {sup 22}Na(p,{gamma}){sup 23}Mg. In the indirect determination of the resonance strength of the lowest states, which were not accessible by direct methods, some of the spin-parity-assignments remained experimentally uncertain. We have investigated these states with shell model, Coulomb displacement, and Thomas-Ehrman shift calculations. From the comparison of calculated and observed properties, we relate the lowest relevant resonance state at E{sub x}=7643 keV to an excited 3/2{sup +} state in accordance with a recent experimental determination by Jenkins et al. From this we deduce significantly improvedmore » values for the {sup 22}Na(p,{gamma}){sup 23}Mg reaction rate at stellar temperatures below T{sub 9}=0.1 K.« less

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

NASA Astrophysics Data System (ADS)

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

2012-11-01

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

Temperature invariance of NaCl solubility in water: inferences from salt-water cluster behavior of NaCl, KCl, and NH4Cl.

PubMed

Bharmoria, Pankaj; Gupta, Hariom; Mohandas, V P; Ghosh, Pushpito K; Kumar, Arvind

2012-09-27

The growth and stability of salt-water clusters have been experimentally studied in aqueous solutions of NaCl, KCl, and NH(4)Cl from dilute to near-saturation conditions employing dynamic light scattering and zeta potential measurements. In order to examine cluster stability, the changes in the cluster sizes were monitored as a function of temperature. Compared to the other cases, the average size of NaCl-water clusters remained almost constant over the studied temperature range of 20-70 °C. Information obtained from the temperature-dependent solution compressibility (determined from speed of sound and density measurements), multinuclear NMR ((1)H, (17)O, (35)Cl NMR), and FTIR were utilized to explain the cluster behavior. Comparison of NMR chemical shifts of saturated salt solutions with solid-state NMR data of pure salts, and evaluation of spectral modifications in the OH stretch region of saturated salt solutions as compared to that of pure water, provided important clues on ion pair-water interactions and water structure in the clusters. The high stability and temperature independence of the cluster sizes in aqueous NaCl shed light on the temperature invariance of its solubility.

Independent modulation of the activity of alpha-ketoglutarate dehydrogenase complex by Ca2+ and Mg2+.

PubMed

Panov, A; Scarpa, A

1996-01-16

The activity of alpha-ketoglutarate dehydrogenase complex (KGDHC), an important enzyme regulating several metabolic pathways, could be regulated by changes in the environment within the mitochondrial matrix. It has been postulated that the activity of this and other dehydrogenases in vivo could be modulated by changes in the intramitochondrial concentrations of Ca2+ or Mg2+. Using a purified alpha-ketoglutarate dehydrogenase from pig hearts, the effect of Ca2+ and/or Mg2+ on the enzyme activity was investigated. Either Ca2+ or Mg2+ increased enzyme activity, and the effects were additive if the concentrations of free divalent cations were below 0.1 and 1 mM for Ca2+ and Mg2+, respectively. In the presence of 1 mM alpha-ketoglutarate and other cofactors, the KM for Mg2+ was 25 microM and less than 1 microM for Ca2+. The KM for alpha-ketoglutarate was a function of the divalent cation(s) present: 4 +/- 1.1 mM in the absence of Ca2+, with or without Mg2+; 2.2 mM in the presence of 1.8 microM Ca2+ alone; and 0.3 mM in the presence of both Ca2+ and Mg2+. Mg2+ increased KGDHC activity only in the presence of thiamine pyrophosphate (TPP) indicating that KGDHC requires both TPP and Mg2+ for enzyme's maximal activity. The affinity of KGDHC for NAD+ is significantly changed by either Mg2+ or Ca2+. The conclusions are that changes in both Ca2+ and Mg2+, in concentrations possibly occurring within mitochondria, could control KGDHC activity and that thiamine pyrophosphate is required for maximal enzyme activity.

The Solubility of Aluminum in Cryolite-Based Electrolyte-Containing KF

NASA Astrophysics Data System (ADS)

Zhang, Yu; Yu, Jiangyu; Gao, Bingliang; Liu, Yibai; Hu, Xianwei; Shi, Zhongning; Wang, Zhaowen

2016-04-01

The solubility of aluminum in NaF-AlF3-CaF2-KF-A12O3 electrolyte system at 1253 K (980 °C) has been measured by the analysis of quenched samples saturated with aluminum. The content of the dissolved metal in the quenched melt was determined by collecting the volume of hydrogen gas when a finely crushed sample is treated with HCl. Addition of 0 to 5 pct KF has no obvious effect on the solubility of aluminum in cryolite-based melts with molar ratio of NaF/AlF3 (cryolite ratio) ranging from 2.2 to 3.0. The solubility of aluminum increases from 0.015 to 0.026 wt pct with cryolite ratio increases from 2.2 to 4.0 in the NaF-AlF3-5 wt pct CaF2-3 wt pct A12O3 electrolyte at 1253 K (980 °C). Aluminum solubility was affected by both chemical replacement reaction of Al + 3NaF = AlF3 + 3Na and physical dissolution.

Crystallization and preliminary X-ray diffraction study of phosphoribosyl pyrophosphate synthetase from E. Coli

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

Timofeev, V. I., E-mail: inna@ns.crys.ras.ru; Abramchik, Yu. A., E-mail: tostars@mail.ru; Zhukhlistova, N. E., E-mail: ugama@yandex.ru

2015-09-15

Enzymes of the phosphoribosyl pyrophosphate synthetase family (PRPPS, EC 2.7.6.1) catalyze the formation of 5-phosphoribosyl pyrophosphate (5-PRPP) from adenosine triphosphate and ribose 5-phosphate. 5-Phosphoribosyl pyrophosphate is an important intermediate in the synthesis of purine, pyrimidine, and pyridine nucleotides, as well as of the amino acids histidine and tryptophan. The crystallization conditions for E. coli PRPPS were found by the vapor-diffusion technique and were optimized to apply the capillary counter-diffusion technique. The X-ray diffraction data set was collected from the crystals grown by the counter-diffusion technique using a synchrotron radiation source to 3.1-Å resolution. The crystals of PRPPS belong to sp.more » gr. P6{sub 3}22 and have the following unit-cell parameters: a = b = 104.44 Å, c = 124.98 Å, α = β = 90°, γ = 120°. The collected X-ray diffraction data set is suitable for the solution of the three-dimensional structure of PRPPS at 3.1-Å resolution.« less

A Micro-Polyethylene Glycol Precipitation Assay as a Relative Solubility Screening Tool for Monoclonal Antibody Design and Formulation Development.

PubMed

Toprani, Vishal M; Joshi, Sangeeta B; Kueltzo, Lisa A; Schwartz, Richard M; Middaugh, C Russell; Volkin, David B

2016-08-01

Adequate protein solubility is an important prerequisite for development, manufacture, and administration of biotherapeutic drug candidates, especially for high-concentration protein formulations. A previously established method for determining the relative apparent solubility (thermodynamic activity) of proteins using polyethylene glycol (PEG) precipitation is adapted for screening and comparing monoclonal antibody (mAb) candidates where only limited quantities (≤1 mg) are available. This micro-PEG assay is used to evaluate various broadly neutralizing mAb candidates to HIV-1 viral spike (gp120 and gp41 glycoproteins). Using ∼1 mg of VRC01-WT mAb per assay, the precision of the micro-PEG assay was established. A series of 7 different broadly neutralizing mAbs to the HIV-1 viral spike proteins were compared by curve shape (%PEG vs. protein concentration), %PEGmidpoint determinations, and extrapolated apparent solubility values. Numerous formulation conditions were then evaluated for their relative effects on the VRC01-WT mAb. The PEGmidpt and apparent solubility values of VRC01-WT mAb decreased as the solution pH increased and increased as NaCl and arginine were added. A final optimization of the micro-PEG assay established that amounts as low as 0.1-0.2 mg can be used. Thus, the micro-PEG assay has significant potential as a relative solubility screening tool during candidate selection and early formulation development. Copyright © 2016 American Pharmacists Association®. All rights reserved.

CRYSTALLINE INORGANIC PYROPHOSPHATASE ISOLATED FROM BAKER'S YEAST

PubMed Central

Kunitz, M.

1952-01-01

Crystalline inorganic pyrophosphatase has been isolated from baker's yeast. The crystalline enzyme is a protein of the albumin type with an isoelectric point near pH 4.8. Its molecular weight is of the order of 100,000. It contains about 5 per cent tyrosine and 3.5 per cent tryptophane. It is most stable at pH 6.8. The new crystalline protein acts as a specific catalyst for the hydrolysis of inorganic pyrophosphate into orthophosphate ions. It does not catalyze the hydrolysis of the pyrophosphate radical of such organic esters as adenosine di- and triphosphate, or thiamine pyrophosphate. Crystalline pyrophosphatase requires the presence of Mg, Co, or Mn ions as activators. These ions are antagonized by calcium ions. Mg is also antagonized by Co or Mn ions. The rate of the enzymatic hydrolysis of inorganic pyrophosphate is proportional to the concentration of enzyme and is a function of pH, temperature, concentration of substrate, and concentration of activating ion. The approximate conditions for optimum rate are: 40°C. and pH 7.0 at a concentration of 3 to 4 x 10–3 M Na4P2O7 and an equivalent concentration of magnesium salt. The enzymatic hydrolysis of Na4P2O7 or K4P2O7 proceeds to completion and is irreversible under the conditions at which hydrolysis is occurring. Details are given of the method of isolation of the crystalline enzyme. PMID:14898026

The apparent solubility of aluminum (III) in Hanford high-level waste.

PubMed

Reynolds, Jacob G

2012-01-01

The solubility of aluminum in Hanford nuclear waste impacts on the processability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity. Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono-, di- and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH)(4)-H(2)O system, and the NaOH-NaAl(OH)(4)-NaCl-H(2)O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than 2M. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems is small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above 2M. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect.

Synthesis, crystal structure and spectroscopy properties of Na 3AZr(PO 4) 3 ( A=Mg, Ni) and Li 2.6Na 0.4NiZr(PO 4) 3 phosphates

NASA Astrophysics Data System (ADS)

Chakir, M.; El Jazouli, A.; de Waal, D.

2006-06-01

Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li 2.6Na 0.4NiZr(PO 4) 3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO 4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni 2+ ions.

Crystal structure of the mineral (Na,Ca,K)2(Ca,Na)4(Mg,Fe)5(Mg,Fe,Ti)5[Si12Al4O44](F,O)4: a triclinic representative of the amphibole family

NASA Astrophysics Data System (ADS)

Rastsvetaeva, R. K.; Aksenov, S. M.

2012-05-01

A mineral belonging to the amphibole family found at the Rothenberg paleovolcano (Eifel, Germany) was studied by single-crystal X-ray diffraction. The triclinic pseudomonoclinic unit-cell parameters are a = 5.3113(1) Å, b = 18.0457(3) Å; c = 9.8684(2) Å, α = 90.016(2)°, β = 105.543(4)°, γ = 89.985(2)°. The structure was solved by direct methods in sp. gr. P1 and refined to the R factor of 2.7% based on 6432 reflections with | F| > 3σ( F) taking into account twinning. The mineral with the idealized formula (Na,Ca,K)2(Ca,Na)4(Mg,Fe)5(Mg,Fe,Ti)5[Si12Al4O44](F,O)4 has some symmetry and structural features that distinguish it from other minerals of this family.

Stabilized-solubilized ferric pyrophosphate as a new iron source for food fortification. Bioavailability studies by means of the prophylactic-preventive method in rats.

PubMed

Salgueiro, M J; Arnoldi, S; Kaliski, M A; Torti, H; Messeri, E; Weill, R; Zubillaga, M; Boccio, J

2009-02-01

The purpose of the present work was to evaluate the iron bioavailability of a new ferric pyrophosphate salt stabilized and solubilized with glycine. The prophylactic-preventive test in rats, using ferrous sulfate as the reference standard, was applied as the evaluating methodology both using water and yogurt as vehicles. Fifty female Sprague-Dawley rats weaned were randomized into five different groups (group 1: FeSO(4); group 2: pyr; group 3: FeSO(4) + yogurt; group 4: pyr + yogurt and group 5: control). The iron bioavailability (BioFe) of each compound was calculated using the formula proposed by Dutra-de-Oliveira et al. where BioFe % = (HbFef - HbFei) x 100/ToFeIn. Finally, the iron bioavailability results of each iron source were also given as relative biological value (RBV) using ferrous sulfate as the reference standard. The results showed that both BioFe % and RBV % of the new iron source tested is similar to that of the reference standard independently of the vehicle employed for the fortification procedure (FeSO(4) 49.46 +/- 12.0% and 100%; Pyr 52.66 +/- 15.02% and 106%; FeSO(4) + yogurth 54.39 +/- 13.92% and 110%; Pyr + yogurt 61.97 +/- 13.54% and 125%; Control 25.30 +/- 6.60, p < 0.05). Therefore, the stabilized and soluble ferric pyrophosphate may be considered as an optimal iron source for food fortification.

Molecular simulation of aqueous electrolyte solubility. 2. Osmotic ensemble Monte Carlo methodology for free energy and solubility calculations and application to NaCl.

PubMed

Moučka, Filip; Lísal, Martin; Škvor, Jiří; Jirsák, Jan; Nezbeda, Ivo; Smith, William R

2011-06-23

We present a new and computationally efficient methodology using osmotic ensemble Monte Carlo (OEMC) simulation to calculate chemical potential-concentration curves and the solubility of aqueous electrolytes. The method avoids calculations for the solid phase, incorporating readily available data from thermochemical tables that are based on well-defined reference states. It performs simulations of the aqueous solution at a fixed number of water molecules, pressure, temperature, and specified overall electrolyte chemical potential. Insertion/deletion of ions to/from the system is implemented using fractional ions, which are coupled to the system via a coupling parameter λ that varies between 0 (no interaction between the fractional ions and the other particles in the system) and 1 (full interaction between the fractional ions and the other particles of the system). Transitions between λ-states are accepted with a probability following from the osmotic ensemble partition function. Biasing weights associated with the λ-states are used in order to efficiently realize transitions between them; these are determined by means of the Wang-Landau method. We also propose a novel scaling procedure for λ, which can be used for both nonpolarizable and polarizable models of aqueous electrolyte systems. The approach is readily extended to involve other solvents, multiple electrolytes, and species complexation reactions. The method is illustrated for NaCl, using SPC/E water and several force field models for NaCl from the literature, and the results are compared with experiment at ambient conditions. Good agreement is obtained for the chemical potential-concentration curve and the solubility prediction is reasonable. Future improvements to the predictions will require improved force field models.

Hygroscopic properties of internally mixed particles composed of NaCl and water-soluble organic acids.

PubMed

Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei; Laskin, Alexander

2014-02-18

Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water-soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy, atomic force microscopy, and X-ray elemental microanalysis. Hygroscopic properties of internally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of sodium malonate and sodium glutarate salts resulted by HCl evaporation from dehydrating particles.

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

NASA Astrophysics Data System (ADS)

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

2007-12-01

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

Improving the Performance of Layered Oxide Cathode Materials with Football-Like Hierarchical Structure for Na-Ion Batteries by Incorporating Mg2+ into Vacancies in Na-Ion Layers.

PubMed

Li, Zheng-Yao; Wang, Huibo; Chen, Dongfeng; Sun, Kai; Yang, Wenyun; Yang, Jinbo; Liu, Xiangfeng; Han, Songbai

2018-04-09

The development of advanced cathode materials is still a great interest for sodium-ion batteries. The feasible commercialization of sodium-ion batteries relies on the design and exploitation of suitable electrode materials. This study offers a new insight into material design to exploit high-performance P2-type cathode materials for sodium-ion batteries. The incorporation of Mg 2+ into intrinsic Na + vacancies in Na-ion layers can lead to a high-performance P2-type cathode material for sodium-ion batteries. The materials prepared by the coprecipitation approach show a well-defined morphology of secondary football-like hierarchical structures. Neutron power diffraction and refinement results demonstrate that the incorporation of Mg 2+ into intrinsic vacancies can enlarge the space for Na-ion diffusion, which can increase the d-spacing of the (0 0 2) peak and the size of slabs but reduce the chemical bond length to result in an enhanced rate capability and cycling stability. The incorporation of Mg 2+ into available vacancies and a unique morphology make Na 0.7 Mg 0.05 Mn 0.8 Ni 0.1 Co 0.1 O 2 a promising cathode, which can be charged and discharged at an ultra-high current density of 2000 mA g -1 with an excellent specific capacity of 60 mAh g -1 . This work provides a new insight into the design of electrode materials for sodium-ion batteries. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple tools for assembling and searching high-density picolitre pyrophosphate sequence data.

PubMed

Parker, Nicolas J; Parker, Andrew G

2008-04-18

The advent of pyrophosphate sequencing makes large volumes of sequencing data available at a lower cost than previously possible. However, the short read lengths are difficult to assemble and the large dataset is difficult to handle. During the sequencing of a virus from the tsetse fly, Glossina pallidipes, we found the need for tools to search quickly a set of reads for near exact text matches. A set of tools is provided to search a large data set of pyrophosphate sequence reads under a "live" CD version of Linux on a standard PC that can be used by anyone without prior knowledge of Linux and without having to install a Linux setup on the computer. The tools permit short lengths of de novo assembly, checking of existing assembled sequences, selection and display of reads from the data set and gathering counts of sequences in the reads. Demonstrations are given of the use of the tools to help with checking an assembly against the fragment data set; investigating homopolymer lengths, repeat regions and polymorphisms; and resolving inserted bases caused by incomplete chain extension. The additional information contained in a pyrophosphate sequencing data set beyond a basic assembly is difficult to access due to a lack of tools. The set of simple tools presented here would allow anyone with basic computer skills and a standard PC to access this information.

Effects of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in Wistar rats.

PubMed

Olatunji, Lawrence A; Usman, Taofeek O; Adebayo, Joseph O; Olatunji, Victoria A

2012-09-01

To investigate the effects of oral administration of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in rats. The 25 and 50 mg/(kg·d) of aqueous extracts of H. sabdariffa were respectively given to rats in the experimental groups for 28 d, and rats in the control group received an appropriate volume of distilled water as vehicle. Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in the kidney were assayed by spectrophotometric method. Administrations of 25 and 50 mg/(kg·d) of aqueous extract of H. sabdariffa significantly decreased the Ca(2+)-Mg(2+)-ATPase activity in the kidney of rats (P<0.05). However, the renal Na(+)-K(+)-ATPase activity of the experimental rats was not affected by either dose of the extract. And the plasma Na(+), K(+) and Ca(2+) levels of the experimental rats had no significant changes. Administration of either dose of the extract did not result in any significant changes in body and kidney weights, the concentrations of plasma albumin and total protein, and alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase activities. However, concentrations of creatinine and urea were significantly reduced by 50 mg/kg of the extract (P<0.05). The present study indicates that oral administration of aqueous extract of H. sabdariffa may preserve the renal function despite a decreased renal Ca(2+)-Mg(2+)-ATPase activity.

The comparative clinical efficacy of pyrophosphate/triclosan, copolymer/triclosan and zinc citrate/triclosan dentifrices for the reduction of supragingival calculus formation.

PubMed

Fairbrother, K J; Kowolik, M J; Curzon, M E; Müller, I; McKeown, S; Hill, C M; Hannigan, C; Bartizek, R D; White, D J

1997-01-01

Three triclosan-containing "multi-benefit" dentifrices were compared for clinical efficacy in reducing supragingival calculus formation following a dental prophylaxis. A total of 544 subjects completed a double-blind parallel-group clinical study using the Volpe-Manhold Index (VMI) to record severity and occurrence of supragingival calculus. The study design included a pre-test period where the calculus formation rate was measured in subjects brushing with a placebo dentifrice. Following a prophylaxis, subjects were stratified for age, gender and VMI scores and assigned to one of four treatments: 1) a dentifrice containing 5.0% soluble pyrophosphate/0.145% fluoride as NaF/silica abrasive/0.28% triclosan (hereafter PPi/TCS-comparable to Crest Complete dentifrice, Procter & Gamble, UK); 2) a commercial dentifrice containing 2.0% Gantrez acid copolymer/ 0.145% fluoride as NaF/silica abrasive/0.30% triclosan (hereafter Gan/TCS-Colgate Total dentifrice, Colgate-Palmolive Company, UK); 3) a commercial dentifrice containing 0.5% zinc citrate trihydrate/0.15% fluoride as sodium monofluorophosphate/silica abrasive/0.20% triclosan (hereafter Zn/TCS-Mentadent P dentifrice, Unilever, UK); and 4) a control dentifrice comprised of 0.145% fluoride as NaF/silica abrasive (hereafter Control). Subjects were instructed to use their assigned dentifrice at least twice per day and to brush as they do normally. Supragingival calculus formation was assesed at two and four months using site-specific and whole-mouth VMI indices for both calculus severity and occurrence. Following four months of use, the PPi/TCS dentifrice provided statistically significant reductions in calculus severity (22-23%) and occurrence (15%) as compared with the Control dentifrice. The Zn/TCS dentifrice also provided significant reductions in calculus severity (17-19%) and occurrence (12-13%) as compared with the Control. The Gan/TCS produced no statistically significant reductions in calculus formation (occurrence

Structure analysis of geranyl pyrophosphate methyltransferase and the proposed reaction mechanism of SAM-dependent C-methylation.

PubMed

Ariyawutthiphan, Orapin; Ose, Toyoyuki; Minami, Atsushi; Shinde, Sandip; Sinde, Sandip; Tsuda, Muneya; Gao, Yong-Gui; Yao, Min; Oikawa, Hideaki; Tanaka, Isao

2012-11-01

In the typical isoprenoid-biosynthesis pathway, condensation of the universal C(5)-unit precursors isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) occurs via the common intermediates prenyl pyrophosphates (C(10)-C(20)). The diversity of isoprenoids reflects differences in chain length, cyclization and further additional modification after cyclization. In contrast, the biosynthesis of 2-methylisonorneol (2-MIB), which is responsible for taste and odour problems in drinking water, is unique in that it primes the enzymatic methylation of geranyl pyrophosphate (GPP) before cyclization, which is catalyzed by an S-adenosyl-L-methionine-dependent methyltransferase (GPPMT). The substrate of GPPMT contains a nonconjugated olefin and the reaction mechanism is expected to be similar to that of the steroid methyltransferase (SMT) family. Here, structural analysis of GPPMT in complex with its cofactor and substrate revealed the mechanisms of substrate recognition and possible enzymatic reaction. Using the structures of these complexes, methyl-group transfer and the subsequent proton-abstraction mechanism are discussed. GPPMT and SMTs contain a conserved glutamate residue that is likely to play a role as a general base. Comparison with the reaction mechanism of the mycolic acid cyclopropane synthase (MACS) family also supports this result. This enzyme represented here is the first model of the enzymatic C-methylation of a nonconjugated olefin in the isoprenoid-biosynthesis pathway. In addition, an elaborate system to avoid methylation of incorrect substrates is proposed.

Effects of a low severity prescribed fire on water-soluble elements in ash from a cork oak (Quercus suber) forest located in the northeast of the Iberian Peninsula

USGS Publications Warehouse

Pereira, P.; beda, X.; Martin, D.; Mataix-Solera, J.; Guerrero, C.

2011-01-01

Wildfire is the major disturbance in Mediterranean forests. Prescribed fire can be an alternative to reduce the amount of fuel and hence decrease the wildfire risk. However the effects of prescribed fire must be studied, especially on ash properties, because ash is an important nutrient source for ecosystem recovery. The aim of this study is to determine the effects of a low severity prescribed fire on water-soluble elements in ash including pH, electrical conductivity (EC), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), silica (SiO2) and total sulphur (TS). A prescribed fire was conducted in a cork oak (Quercus suber) (Q.S) forest located in the northeast part of the Iberian Peninsula. Samples were collected from a flat plot of 40??70m mainly composed of Q.S and Quercus robur (Q.R) trees. In order to understand the effects of the prescribed fire on the soluble elements in ash, we conducted our data analysis on three data groups: all samples, only Q.S samples and only Q.R samples. All three sample groups exhibited a significant increase in pH, EC (p<0.001), water-soluble Ca, Mg, Na, SiO2 and TS and a decrease in water-soluble Mn, Fe and Zn. Differences were identified between oak species for water-soluble K, Al and Fe. In Q.S samples we registered a significant increase in the first two elements p<0.001 and p<0.01, respectively, and a non-significant impact in the third, at p<0.05. In Q.R data we identified a non-significant impact on water-soluble K and Al and a significant decrease in water-soluble Fe (p<0.05). These differences are probably due to vegetation characteristics and burn severity. The fire induced a higher variability in the ash soluble elements, especially in Q.S samples, that at some points burned with higher severity. The increase of pH, EC, Ca, Mg, Na and K will improve soil fertility, mainly in the study area where soils are acidic. The application of this low severity prescribed

Effects of a low severity prescribed fire on water-soluble elements in ash from a cork oak (Quercus suber) forest located in the northeast of the Iberian Peninsula.

PubMed

Pereira, Paulo; Ubeda, Xavier; Martin, Deborah; Mataix-Solera, Jorge; Guerrero, César

2011-02-01

Wildfire is the major disturbance in Mediterranean forests. Prescribed fire can be an alternative to reduce the amount of fuel and hence decrease the wildfire risk. However the effects of prescribed fire must be studied, especially on ash properties, because ash is an important nutrient source for ecosystem recovery. The aim of this study is to determine the effects of a low severity prescribed fire on water-soluble elements in ash including pH, electrical conductivity (EC), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), silica (SiO(2)) and total sulphur (TS). A prescribed fire was conducted in a cork oak (Quercus suber) (Q.S) forest located in the northeast part of the Iberian Peninsula. Samples were collected from a flat plot of 40×70m mainly composed of Q.S and Quercus robur (Q.R) trees. In order to understand the effects of the prescribed fire on the soluble elements in ash, we conducted our data analysis on three data groups: all samples, only Q.S samples and only Q.R samples. All three sample groups exhibited a significant increase in pH, EC (p<0.001), water-soluble Ca, Mg, Na, SiO(2) and TS and a decrease in water-soluble Mn, Fe and Zn. Differences were identified between oak species for water-soluble K, Al and Fe. In Q.S samples we registered a significant increase in the first two elements p<0.001 and p<0.01, respectively, and a non-significant impact in the third, at p<0.05. In Q.R data we identified a non-significant impact on water-soluble K and Al and a significant decrease in water-soluble Fe (p<0.05). These differences are probably due to vegetation characteristics and burn severity. The fire induced a higher variability in the ash soluble elements, especially in Q.S samples, that at some points burned with higher severity. The increase of pH, EC, Ca, Mg, Na and K will improve soil fertility, mainly in the study area where soils are acidic. The application of this low severity

Prediction of halite, gypsum, and anhydrite solubility in natural brines under subsurface conditions

NASA Astrophysics Data System (ADS)

He, Shiliang; Morse, John W.

1993-01-01

Prediction of the solubility of the evaporite minerals halite, gypsum, and anhydrite in brines has numerous scientific and practical applications. This paper presents a Pitzer equation-based model for predicting the solubility of these minerals in Na +-K +-H +-Ca 2+-Mg 2+-Cl --OH --SO 42--H 2O solutions of varying composition as a function of temperature and pressure. Model predictions compare well with experimental observations. As an example of the utility of this program, the volume of CaSO 4 precipitated as a brine flows up a pipe from 6000 m depth is predicted. This is done as a function of flow distance for different cooling rates of the brine. Results indicate that if the brine can be cooled to near the geothermal gradient no precipitation will take place.

Phase relations in the system NaCl-KCl-H 2O. III: Solubilities of halite in vapor-saturated liquids above 445°C and redetermination of phase equilibrium properties in the system NaCl-H 2O to 1000°C and 1500 bars

NASA Astrophysics Data System (ADS)

Chou, I.-Ming

1987-07-01

Halite solubilities along the three-phase curve in the binary system NaCl-H 2O determined by DTA experiment can be represented by the equation Wt.% NaCl (±0.2) = 19.39 - 0.0364 t + 3.553 × 10 -4T2 - 2.298 × 10 -7T3, where 447≦ T ≦ 800° C. Even though these halite solubilities are up to ~7 wt.% higher than those reported in literature, extrapolated values at temperatures below 447°C merge with the literature values. It is considered that the equation adequately describes halite solubilities between 382 and 800°C. The newly established solubility data are believed to be more reliable because they are compatible with data obtained by using synthetic fluid inclusions and with the observed DTA signals and also because they were measured in a relatively corrosion-free system. In an earlier publication (GUNTER et al., 1983), we were puzzled greatly by multiple and rather unreproducible DTA peaks appearing during isobaric cooling (heating experiments were nondefinitive) at pressures below about 500 bars. These DTA signals apparently suggested that the "halite liquidus" swung sharply upward in temperature as pressure decreased from about 500 bars to that of the halite-saturated boiling curve. Further analysis of the data and helpful discussions with several individuals have revealed that the behavior is a consequence of the initial (precooling) separation of the fluid into NaCl-poor gas and NaCl-rich liquid that failed to homogenize in the short time encompassed by the DTA experiments. The present analysis is based on extrapolations of the dP/dT slopes from pressures above 500 bars. Through use of these new halite solubility data and the data from synthetic fluid inclusions [formed by healing fractures in inclusion-free Brazilian quartz in the presence of two coexisting, immiscible NaCl-H 2O fluids at various temperatures and pressures (Bodnar et al., 1985)], phase equilibria in the system NaCl-H 2O have been redetermined to 1000°C and 1500 bars.

Raman microspectroscopic study of effects of Na(I) and Mg(II) ions on low pH induced DNA structural changes.

PubMed

Muntean, C M; Segers-Nolten, G M J

2003-01-01

In this work a confocal Raman microspectrometer is used to investigate the influence of Na(+) and Mg(2+) ions on the DNA structural changes induced by low pH. Measurements are carried out on calf thymus DNA at neutral pH (7) and pH 3 in the presence of low and high concentrations of Na(+) and Mg(2+) ions, respectively. It is found that low concentrations of Na(+) ions do not protect DNA against binding of H(+). High concentrations of monovalent ions can prevent protonation of the DNA double helix. Our Raman spectra show that low concentrations of Mg(2+) ions partly protect DNA against protonation of cytosine (line at 1262 cm(-1)) but do not protect adenine and guanine N(7) against binding of H(+) (characteristic lines at 1304 and 1488 cm(-1), respectively). High concentrations of Mg(2+) can prevent protonation of cytosine and protonation of adenine (disruption of AT pairs). By analyzing the line at 1488 cm(-1), which obtains most of its intensity from a guanine vibration, high magnesium salt protect the N(7) of guanine against protonation. A high salt concentration can prevent protonation of guanine, cytosine, and adenine in DNA. Higher salt concentrations cause less DNA protonation than lower salt concentrations. Magnesium ions are found to be more effective in protecting DNA against binding of H(+) as compared with calcium ions presented in a previous study. Divalent metal cations (Mg(2+), Ca(2+)) are more effective in protecting DNA against protonation than monovalent ions (Na(+)). Copyright 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 000-000, 2003

Investigating the solubility and cytocompatibility of CaO-Na2 O-SiO2 /TiO2 bioactive glasses.

PubMed

Wren, Anthony W; Coughlan, Aisling; Smith, Courtney M; Hudson, Sarah P; Laffir, Fathima R; Towler, Mark R

2015-02-01

This study aims to investigate the solubility of a series of titanium (TiO2 )-containing bioactive glasses and their subsequent effect on cell viability. Five glasses were synthesized in the composition range SiO2 -Na2 O-CaO with 5 mol % of increments TiO2 substituted for SiO2 . Glass solubility was investigated with respect to (1) exposed surface area, (2) particle size, (3) incubation time, and (4) compositional effects. Ion release profiles showed that sodium (Na(+) ) presented high release rates after 1 day and were unchanged between 7 and 14 days. Calcium (Ca(2+) ) release presented a significant change at each time period and was also composition dependent, where a reduction in Ca(2+) release is observed with an increase in TiO2 concentration. Silica (Si(4+) ) release did not present any clear trends while no titanium (Ti(4+) ) was released. Cell numbers were found to increase up to 44%, compared to the growing control population, with a reduction in particle size and with the inclusion of TiO2 in the glass composition. © 2014 Wiley Periodicals, Inc.

Structural Basis for Flip-Flop Action of Thiamin Pyrophosphate-dependent Enzymes Revealed by Human Pyruvate Dehydrogenase

NASA Technical Reports Server (NTRS)

Ciszak, Ewa M.; Korotchkina, Lioubov G.; Dominiak, Paulina M.; Sidhu, Sukdeep; Patel, Mulchand S.

2003-01-01

The derivative of vitamin B1, thiamin pyrophosphate, is a cofactor of enzymes performing catalysis in pathways of energy production. In alpha (sub 2) beta (sub 2)-heterotetrameric human pyruvate dehydrogenase, this cofactor is used to cleave the C(sup alpha) -C(=O) bond of pyruvate followed by reductive acetyl transfer to lipoyl-dihydrolipoamide acetyltransferase. The dynamic nonequivalence of two, otherwise chemically equivalent, catalytic sites has not yet been understood. To understand the mechanism of action of this enzyme, we determined the crystal structure of the holo-form of human pyruvate dehydrogenase at 1.95-Angstrom resolution. We propose a model for the flip-flop action of this enzyme through a concerted approximately 2-Angstrom shuttle-like motion of its heterodimers. Similarity of thiamin pyrophosphate binding in human pyruvate dehydrogenase with functionally related enzymes suggests that this newly defined shuttle-like motion of domains is common to the family of thiamin pyrophosphate-dependent enzymes.

The apparent solubility of aluminum (III) in Hanford high-level waste

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

Reynolds, Jacob G.

2012-12-01

The solubility of aluminum in Hanford nuclear waste impacts on the process ability of the waste by a number of proposed treatment options. For many years, Hanford staff has anecdotally noted that aluminum appears to be considerably more soluble in Hanford waste than the simpler electrolyte solutions used as analogues. There has been minimal scientific study to confirm these anecdotal observations, however. The present study determines the apparent solubility product for gibbsite in 50 tank samples. The ratio of hydroxide to aluminum in the liquid phase for the samples is calculated and plotted as a function of total sodium molarity.more » Total sodium molarity is used as a surrogate for ionic strength, because the relative ratios of mono, di and trivalent anions are not available for all of the samples. These results were compared to the simple NaOH-NaAl(OH{sub 4})H{sub 2}O system, and the NaOH-NaAl(OH{sub 4})NaCl-H{sub 2}O system data retrieved from the literature. The results show that gibbsite is apparently more soluble in the samples than in the simple systems whenever the sodium molarity is greater than two. This apparent enhanced solubility cannot be explained solely by differences in ionic strength. The change in solubility with ionic strength in simple systems is small compared to the difference between aluminum solubility in Hanford waste and the simple systems. The reason for the apparent enhanced solubility is unknown, but could include. kinetic or thermodynamic factors that are not present in the simple electrolyte systems. Any kinetic explanation would have to explain why the samples are always supersaturated whenever the sodium molarity is above two. Real waste characterization data should not be used to validate thermodynamic solubility models until it can be confirmed that the apparent enhanced gibbsite solubility is a thermodynamic effect and not a kinetic effect.« less

Hyaline cartilage involvement in patients with gout and calcium pyrophosphate deposition disease. An ultrasound study.

PubMed

Filippucci, E; Riveros, M Gutierrez; Georgescu, D; Salaffi, F; Grassi, W

2009-02-01

The main aim of the present study was to determine the sensitivity, specificity and accuracy of ultrasonography (US) in detecting monosodium urate and calcium pyrophosphate dihydrate crystals deposits at knee cartilage level using clinical definite diagnosis as standard reference. A total of 32 patients with a diagnosis of gout and 48 patients with pyrophosphate arthropathy were included in the study. Fifty-two patients with rheumatoid arthritis (RA), psoriatic arthritis or osteoarthritis (OA) were recruited as disease controls. All diagnoses were made using an international clinical criterion. US examinations were performed by an experienced sonographer, blind to clinical and laboratory data. Hyaline cartilage was assessed to detect two US findings recently indicated as indicative of crystal deposits: hyperechoic enhancement of the superficial margin of the hyaline cartilage and hyperechoic spots within the cartilage layer not generating a posterior acoustic shadow. Hyperechoic enhancement of the chondrosynovial margin was found in at least one knee of 14 out of 32 (43.7%) patients with gout and in a single knee of only one patient affected by pyrophosphate arthropathy (specificity=99%). Intra-cartilaginous hyperechoic spots were detected in at least one knee of 33 out of 48 (68.7%) patients with pyrophosphate arthropathy and in two disease controls one with OA and the second with RA (specificity=97.6%). The results of the present study indicate that US may play a relevant role in distinguishing cartilage involvement in patients with crystal-related arthropathy. The selected US findings were found to be highly specific.

In vitro evaluation of iron solubility and dialyzability of various iron fortificants and of iron-fortified milk products targeted for infants and toddlers.

PubMed

Kapsokefalou, Maria; Alexandropoulou, Isidora; Komaitis, Michail; Politis, Ioannis

2005-06-01

The objectives of the present study were: to compare the solubility and dialyzability of various iron fortificants (iron pyrophosphate, ferrous bis-glycinate, ferrous gluconate, ferrous lactate, ferrous sulfate) added, in the presence of ascorbic acid, to pasteurized milk samples produced under laboratory conditions; and to compare the solubility and dialyzability of iron in commercial pasteurized, UHT and condensed milk products available in the Greek market fortified with various vitamins and minerals including iron and targeted towards infants (6-12 months old) and toddlers. Iron solubility and dialyzability were determined using a simulated gastrointestinal digestive system. Ferrous dialyzable iron (molecular weight lower than 8000) was used as an index for prediction of iron bioavailability. Ferrous dialyzable iron in pasteurized milk samples fortified with iron pyrophosphate, ferrous lactate and ferrous bis-glycinate was higher (P < 0.05) than that in milk samples fortified with ferrous sulfate and ferrous gluconate. In commercial liquid pasteurized or UHT milk products, formation of ferrous dialyzable iron in products fortified with ferrous lactate was not different (P > 0.05) from those fortified with ferrous sulfate. Ferrous dialyzable iron in four condensed commercial milk products was higher (P < 0.05) than the corresponding values of the liquid UHT milk samples fortified with the same fortificant (ferrous sulfate). Ferrous dialyzable iron was higher (P < 0.05) in products targeted for infants compared with those targeted for toddlers. In conclusion, the type of iron source, milk processing and the overall product composition affect formation of ferrous dialyzable iron and may determine the success and effectiveness of iron fortification of milk.

Inositol pyrophosphates promote tumor growth and metastasis by antagonizing liver kinase B1

PubMed Central

Rao, Feng; Xu, Jing; Fu, Chenglai; Cha, Jiyoung Y.; Gadalla, Moataz M.; Xu, Risheng; Barrow, James C.; Snyder, Solomon H.

2015-01-01

The inositol pyrophosphates, molecular messengers containing an energetic pyrophosphate bond, impact a wide range of biologic processes. They are generated primarily by a family of three inositol hexakisphosphate kinases (IP6Ks), the principal product of which is diphosphoinositol pentakisphosphate (IP7). We report that IP6K2, via IP7 synthesis, is a major mediator of cancer cell migration and tumor metastasis in cell culture and in intact mice. IP6K2 acts by enhancing cell-matrix adhesion and decreasing cell–cell adhesion. This action is mediated by IP7-elicited nuclear sequestration and inactivation of the tumor suppressor liver kinase B1 (LKB1). Accordingly, inhibitors of IP6K2 offer promise in cancer therapy. PMID:25617365

Influence of Na+ and Mg2+ ions on RNA structures studied with molecular dynamics simulations.

PubMed

Fischer, Nina M; Polêto, Marcelo D; Steuer, Jakob; van der Spoel, David

2018-06-01

The structure of ribonucleic acid (RNA) polymers is strongly dependent on the presence of, in particular Mg2+ cations to stabilize structural features. Only in high-resolution X-ray crystallography structures can ions be identified reliably. Here, we perform molecular dynamics simulations of 24 RNA structures with varying ion concentrations. Twelve of the structures were helical and the others complex folded. The aim of the study is to predict ion positions but also to evaluate the impact of different types of ions (Na+ or Mg2+) and the ionic strength on structural stability and variations of RNA. As a general conclusion Mg2+ is found to conserve the experimental structure better than Na+ and, where experimental ion positions are available, they can be reproduced with reasonable accuracy. If a large surplus of ions is present the added electrostatic screening makes prediction of binding-sites less reproducible. Distinct differences in ion-binding between helical and complex folded structures are found. The strength of binding (ΔG‡ for breaking RNA atom-ion interactions) is found to differ between roughly 10 and 26 kJ/mol for the different RNA atoms. Differences in stability between helical and complex folded structures and of the influence of metal ions on either are discussed.

On the solubility of gallium nitride in supercritical ammonia-sodium solutions

NASA Astrophysics Data System (ADS)

Griffiths, Steven; Pimputkar, Siddha; Speck, James S.; Nakamura, Shuji

2016-12-01

Due to the disparity between observed gallium nitride (GaN) growth under conditions for which literature reports normal solubility, GaN solubility in supercritical NH3-Na containing solutions was re-evaluated. Isothermal gravimetric experiments on polycrystalline GaN were performed in the temperature range (T =415-650 °C) for which retrograde growth of GaN routinely occurs (P ≈ 200 MPa, molar NH3:Na fill ratio =20:1). Two previously-unreported error contributions to the gravimetric determination of GaN solubility were identified: Ga-alloying of exposed Ni-containing components, and the presence of a dense, Ga-absorbing Na-rich, second phase under these conditions. Due to the inability to measure Ga-alloying of the exposed autoclave wall for each experiment, considerable scatter was introduced in the refined GaN solubility curve. No clear dependence of GaN solubility on temperature was resolvable, while most solubility values were determined to be within a band of 0.03-0.10 mol% GaN, normalized by fill NH3.

Changes in expression of soluble inorganic pyrophosphatases of Phaseolus vulgaris under phosphate starvation.

PubMed

Hernández-Domíguez, Eric E; Valencia-Turcotte, Lilián G; Rodríguez-Sotres, Rogelio

2012-05-01

Phosphorus is an essential element for all living cells, but its availability is often limiting in the soil. Plants have adapted to such limitation and respond to phosphorus deficiency. The soluble inorganic pyrophosphatases (PPase; EC 3.6.1.1) recycle the pyrophosphate produced by many biosynthetic reactions, and may play a role in the plant adaptation to phosphorus deficiency. In this work, three PPase mRNAs were identified from the Phaseolus vulgaris EST international database and their sequences were corroborated and completed using 3'RACE. After design and validation of the appropriate oligonucleotide primers, the PPase mRNA expression was measured by qRT-PCR in leaves, stems, and roots of bean plants grown with 1mM phosphate or under phosphate starvation. The plant tissues were classified according to their position on the plant, and some physiological signs of stress were recorded. qRT-PCR revealed changes in mRNA expression, but not for all isozymes under analysis, and not for all tissues. In addition, changes in the activity of some PPases were observed in zymograms. Our data are consistent with an important role for pyrophosphate in the adaptation of the plant to phosphate starvation. © 2012 Elsevier Ireland Ltd. All rights reserved.

Giant geode (subchondrial cyst) in calcium pyrophosphate deposition disease on the curist.

PubMed

Weinberg, S; Scott, R A

1981-09-01

It is important to be aware of the radiographic features of pyrophosphate arthropathy with or without associated chondrocalcinosis. Accordingly, when appropriate structural joint changes are present an extraordinarily large subchondral cyst should not prompt a misdiagnosis of cystic tumor.

A Novel Inositol Pyrophosphate Phosphatase in Saccharomyces cerevisiae: Siw14 PROTEIN SELECTIVELY CLEAVES THE β-PHOSPHATE FROM 5-DIPHOSPHOINOSITOL PENTAKISPHOSPHATE (5PP-IP5).

PubMed

Steidle, Elizabeth A; Chong, Lucy S; Wu, Mingxuan; Crooke, Elliott; Fiedler, Dorothea; Resnick, Adam C; Rolfes, Ronda J

2016-03-25

Inositol pyrophosphates are high energy signaling molecules involved in cellular processes, such as energetic metabolism, telomere maintenance, stress responses, and vesicle trafficking, and can mediate protein phosphorylation. Although the inositol kinases underlying inositol pyrophosphate biosynthesis are well characterized, the phosphatases that selectively regulate their cellular pools are not fully described. The diphosphoinositol phosphate phosphohydrolase enzymes of the Nudix protein family have been demonstrated to dephosphorylate inositol pyrophosphates; however, theSaccharomyces cerevisiaehomolog Ddp1 prefers inorganic polyphosphate over inositol pyrophosphates. We identified a novel phosphatase of the recently discovered atypical dual specificity phosphatase family as a physiological inositol pyrophosphate phosphatase. Purified recombinant Siw14 hydrolyzes the β-phosphate from 5-diphosphoinositol pentakisphosphate (5PP-IP5or IP7)in vitro. In vivo,siw14Δ yeast mutants possess increased IP7levels, whereas heterologousSIW14overexpression eliminates IP7from cells. IP7levels increased proportionately whensiw14Δ was combined withddp1Δ orvip1Δ, indicating independent activity by the enzymes encoded by these genes. We conclude that Siw14 is a physiological phosphatase that modulates inositol pyrophosphate metabolism by dephosphorylating the IP7isoform 5PP-IP5to IP6. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Soft-tissue sarcoma: imaged with technetium-99m pyrophosphate

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

Blatt, C.J.; Hayt, D.B.; Desai, M.

1977-11-01

A liposarcoma showed intense concentration of technetium-99m pyrophosphate. An angiogram demonstrated a highly vascular lesion, and it is suggested that blood flow played a major role in allowing the tumor to be demonstrated on scintiphotography. There was some histologic evidence of calcification which probably also contributed to bone-tracer disposition. Quantitative analysis of the specimen demonstrated that this calcification was located primarily in the areas of hemorrhage and necrosis.

Tc-99m pyrophosphate myocardial scanning in Chagas' disease

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

da Rocha, A.F.; Meguerian, B.A.; Harbert, J.C.

1981-04-01

Chagas' disease is a serious protozoan infection affecting up to 20% of populations in some endemic areas. Myocarditis and cardiomyopathy occur in 50% of patients who go on to develop chronic Chagas' disease. We have studied a patient with no overt cardiac symptoms who revealed intense myocardial uptake of Tc-99m pyrophosphate. The significance of this finding in relation to early detection and progress of therapy is explored.

Tc-99m pyrophosphate myocardial scanning in Chagas' disease

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

Goncalves da Rocha, A.F.; Meguerian, B.A.; Harbert, J.C.

1981-04-01

Chagas' disease is a serious protozoan infection affecting up to 20% of populations in some endemic areas. Myocarditis and cardiomyopathy occur in 50% of patients who go on to develop chronic Chagas's disease. We have studied a patient with no overt cardiac symptoms who revealed intense myocardial uptake of Tc-99m pyrophosphate. The significance of this finding in relation to early detection and progress of therapy is explored.

Insoluble zinc, cupric and tin pyrophosphates inhibit the formation of volatile sulphur compounds.

PubMed

Jonski, G; Young, A; Wåler, S M; Rölla, G

2004-10-01

Oral malodour is mainly a result of the production of volatile sulphur compounds (VSC). The present study was concerned with investigating the anti-VSC effect of insoluble pyrophosphates (PP) of zinc, copper(II) and tin(II). The hypothesis to be tested was that the sulphide anions produced when VSC are solubilized in water have a higher affinity for the respective metal ions than the PP anion. The anti-VSC effects of insoluble PP were compared with the corresponding soluble metal salts using three in vitro methods: saliva putrefaction; dialysis of a suspension of PP and saliva against water; and analysis of water containing hydrogen sulphide and methyl mercaptan gases, and gases in the headspace. The levels of VSC were analysed by gas chromatography in the first and third methods, and released metal ions were analysed by atomic absorption spectroscopy in the second. The results showed that: the insoluble metal PP inhibited VSC formation in saliva by 99-100%; under dialysis, only minute amounts of metal ions are released from the combination of PP and saliva; and the PP lost their metal cations in water containing dissolved gases and inhibited VSC formation. Hence, the results support the experimental hypothesis. Sulphide ions are obviously very strong ligands for these metal ions.

Constant Enthalpy Change Value during Pyrophosphate Hydrolysis within the Physiological Limits of NaCl*

PubMed Central

Wakai, Satoshi; Kidokoro, Shun-ichi; Masaki, Kazuo; Nakasone, Kaoru; Sambongi, Yoshihiro

2013-01-01

A decrease in water activity was thought to result in smaller enthalpy change values during PPi hydrolysis, indicating the importance of solvation for the reaction. However, the physiological significance of this phenomenon is unknown. Here, we combined biochemistry and calorimetry to solve this problem using NaCl, a physiologically occurring water activity-reducing reagent. The pyrophosphatase activities of extremely halophilic Haloarcula japonica, which can grow at ∼4 m NaCl, and non-halophilic Escherichia coli and Saccharomyces cerevisiae were maximal at 2.0 and 0.1 m NaCl, respectively. Thus, halophilic and non-halophilic pyrophosphatases exhibit distinct maximal activities at different NaCl concentration ranges. Upon calorimetry, the same exothermic enthalpy change of −35 kJ/mol was obtained for the halophile and non-halophiles at 1.5–4.0 and 0.1–2.0 m NaCl, respectively. These results show that solvation changes caused by up to 4.0 m NaCl (water activity of ∼0.84) do not affect the enthalpy change in PPi hydrolysis. It has been postulated that PPi is an ATP analog, having a so-called high energy phosphate bond, and that the hydrolysis of both compounds is enthalpically driven. Therefore, our results indicate that the hydrolysis of high energy phosphate compounds, which are responsible for biological energy conversion, is enthalpically driven within the physiological limits of NaCl. PMID:23965994

Laboratory and in-situ reductions of soluble phosphorus in swine waste slurries.

PubMed

Burns, R T; Moody, L B; Walker, F R; Raman

2001-11-01

Laboratory and field experiments were conducted using magnesium chloride (MgCl2) to force the precipitation of struvite (MgNH4PO4 x 6H2O) and reduce the concentration of soluble phosphorus (SP) in swine waste. In laboratory experiments, reductions of SP of 76% (572 to 135 mg P l(-1)) were observed in raw swine manure after addition of magnesium chloride (MgCl2) at a rate calculated to provide a 1.6:1 molar ratio of magnesium (Mg) to total phosphorus. Adjusting the pH of the treated manure to pH 9.0 with sodium hydroxide (NaOH) increased SP reduction to 91% (572 to 50 mg P l(-1)). X-ray diffraction of the precipitate recovered from swine waste slurry treated only with MgCl2 confirmed the presence ofstruvite. The molar N:P:Mg ratio of the recovered precipitate was 1:1.95:0.24, suggesting that compounds in addition to struvite were formed. In a field experiment conducted in a swine manure holding pond, a 90% reduction in SP concentration was observed in approximately 140,000 l of swine manure slurry treated before land application with 2,000 l MgCl2 (64% solution) at ambient slurry temperatures ranging from 5 to 10 degrees C.

Zircon: Free Energy of Formation by Aqueous Solubility Measurements at High T and P

NASA Astrophysics Data System (ADS)

Newton, R. C.; Manning, C. E.; Hanchar, J. M.

2002-12-01

We measured the silica solubility at 800 °C, 12 kbar, of small (~0.5 mg) limpid euhedral zircon crystals grown by a flux-melt method (Hanchar et al., Am. Min., 86, 667, 2001). Incongruent solution occurs according to ZrSiO4 = ZrO2 + SiO2,aq. Zircon lost ~0.1 mg after exposure of 1-2 mg of zircon to ~32 mg H2O in welded Pt envelopes for 90-120 hr in piston-cylinder apparatus using NaCl-graphite furnaces. The average solubility was 0.0645+/-0.007 molal (m), or a mole fraction (XS) of 0.00116. Reversibility was established by rerunning the baddeleyite-coated zircons with a fluid initially slightly SiO2-oversaturated, as determined by the forward experiments, resulting in weight gains of the composite crystals. Similar runs on sintered ZrO2 compacts yielded spontaneous surface nucleation and growth of zircons up to 1 mm. Concentrations were corrected for a small, measured solubility of ZrO2 (0.001 m). Nonideality of aqueous silica was calculated assuming that SiO2,aq consists of a mixture of monomers and dimers (Zotov and Keppler (Chem. Geol., 184, 71, 2002; Newton and Manning, GCA, in press). Our zircon solubility and that of quartz at the same conditions (XS=0.02634, Manning, GCA, 58, 4831, 1994) give activity coefficients at the two concentrations of 0.730 and 0.255, respectively. The activity coefficients and concentrations yield the free energy of formation of zircon from the oxides at 800 °C, 12 kbar of -18.46+/-0.96 kJ/mol, which translates to -11.91+/-0.96 kJ/mol at 800 °C, 1 bar. Our value is compatible with previous estimates based on experiment (Schuiling et al., Am. Min., 61, 166, 1976) and high-T oxide-melt calorimetry (Ellison and Navrotsky, J. Am. Ceram. Soc., 75, 1430, 1992), but is four times more precise than these estimates.

PVA/NaCl/MgO nanocomposites-microstructural analysis by whole pattern fitting method

NASA Astrophysics Data System (ADS)

Prashanth, K. S.; Mahesh, S. S.; Prakash, M. B. Nanda; Somashekar, R.; Nagabhushana, B. M.

2018-04-01

The nanofillers in the macromolecular matrix have displayed noteworthy changes in the structure and reactivity of the polymer nanocomposites. Novel functional materials usually consist of defects and are largely disordered. The intriguing properties of these materials are often attributed to defects. X-ray line profiles from powder diffraction reveal the quantitative information about size distribution and shape of diffracting domains which governs the contribution from small conventional X-ray diffraction (XRD) techniques to enumerate the microstructural information. In this study the MgO nanoparticles were prepared by solution combustion method and PVA/NaCl/MgO nanocomposite films were synthesized by the solvent cast method. Microstructural parameters viz crystal defects like stacking faults and twin faults, compositional inhomogeneity, crystallite size and lattice strain (g in %), were extracted using whole pattern fitting method.

Influence of dispersing agents and solution conditions on the solubility of crude kaolin.

PubMed

Zaman, Abbas A; Mathur, Sharad

2004-03-01

Experiments measuring the solubility of kaolin particles in terms of the concentration of aluminum and silicon ions in supernatant were carried out as a function of the pH of the slurry over a wide range of dosages of different dispersing agents varying from 0.5 to 12 mg/(g solids). The concentrations of the metal ions in supernatant were found to be strongly affected by the type and the dosage of the dispersants and pH of the solution. In this study, the mechanism of the reaction between the dispersing agents and kaolin particles was studied and the dissolution capacities of metal ions (aluminum and silicon) were identified from kaolin particles in the absence and presence of dispersing agents. The three anionic dispersing agents used were sodium polyacrylate (Na-PAA), sodium hexametaphosphate (Na-HMP), and sodium silicate (Na-silicate), based on the industrial application of these agents and their ability to produce a stable dispersion for this purpose.

Semi-Empirical Model to Estimate the Solubility of CO2 NaCl Brine in Conditions Representative of CO2 Sequestration

NASA Astrophysics Data System (ADS)

Mohammadian, E.; Hamidi, H.; Azdarpour, A.

2018-05-01

CO2 sequestration is considered as one of the most anticipated methods to mitigate CO2 concentration in the atmosphere. Solubility mechanism is one of the most important and sophisticated mechanisms by which CO2 is rendered immobile while it is being injected into aquifers. A semi-empirical, easy to use model was developed to calculate the solubility of CO2 in NaCl brines with thermodynamic conditions (pressure, temperature) and salinity gradients representative CO2 sequestration in the Malay basin. The model was compared to the previous more sophisticated models and a good consistency was found among the data obtained using the two models. A Sensitivity analysis was also conducted on the model to test its performance beyond its limits.

The 18Ne(α,p)21Na breakout reaction in x-ray bursts: Experimental determination of spin-parities for α resonances in 22Mg via resonant elastic scattering of 21Na+p

NASA Astrophysics Data System (ADS)

He, J. J.; Zhang, L. Y.; Parikh, A.; Xu, S. W.; Yamaguchi, H.; Kahl, D.; Kubono, S.; Hu, J.; Ma, P.; Chen, S. Z.; Wakabayashi, Y.; Sun, B. H.; Wang, H. W.; Tian, W. D.; Chen, R. F.; Guo, B.; Hashimoto, T.; Togano, Y.; Hayakawa, S.; Teranishi, T.; Iwasa, N.; Yamada, T.; Komatsubara, T.

2013-07-01

The 18Ne(α,p)21Na reaction provides a pathway for breakout from the hot CNO cycles to the rp process in type-I x-ray bursts. To better determine this astrophysical reaction rate, the resonance parameters of the compound nucleus 22Mg have been investigated by measuring the resonant elastic scattering of 21Na+p. An 89 MeV 21Na radioactive ion beam was produced at the CNS Radioactive Ion Beam Separator and bombarded an 8.8 mg/cm2 thick polyethylene target. The recoiled protons were measured at scattering angles of θc.m.≈175∘ and 152∘ by three ΔE-E silicon telescopes. The excitation function was obtained with a thick-target method over energies Ex(22Mg) = 5.5-9.2 MeV. The resonance parameters have been determined through an R-matrix analysis. For the first time, the Jπ values for ten states above the α threshold in 22Mg have been experimentally determined in a single consistent measurement. We have made three new Jπ assignments and confirmed seven of the ten tentative assignments in the previous work. The 18Ne(α,p)21Na reaction rate has been recalculated, and the astrophysical impact of our new rate has been investigated through one-zone postprocessing x-ray burst calculations. We find that the 18Ne(α,p)21Na rate significantly affects the peak nuclear energy generation rate and the onset temperature of this breakout reaction in these phenomena.

In-Situ and Real-time Monitoring of Mechanochemical Preparation of Li2 Mg(NH2 BH3 )4 and Na2 Mg(NH2 BH3 )4 and Their Thermal Dehydrogenation.

PubMed

Biliškov, Nikola; Borgschulte, Andreas; Užarević, Krunoslav; Halasz, Ivan; Lukin, Stipe; Milošević, Sanja; Milanović, Igor; Novaković, Jasmina Grbović

2017-11-16

For the first time, in situ monitoring of uninterrupted mechanochemical synthesis of two bimetallic amidoboranes, M 2 Mg(NH 2 BH 3 ) 4 (M=Li, Na), by means of Raman spectroscopy, has been applied. This approach allowed real-time observation of key intermediate phases, and a straightforward follow-up of the reaction course. Detailed analysis of time-dependent spectra revealed a two-step mechanism through MNH 2 BH 3 ⋅NH 3 BH 3 adducts as key intermediate phases which further reacted with MgH 2 , giving M 2 Mg(NH 2 BH 3 ) 4 as final products. The intermediates partially take a competitive pathway toward the oligomeric M(BH 3 NH 2 BH 2 NH 2 BH 3 ) phases. The crystal structure of the novel bimetallic amidoborane Li 2 Mg(NH 2 BH 3 ) 4 was solved from high-resolution powder diffraction data and showed an analogous metal coordination to Na 2 Mg(NH 2 BH 3 ) 4 , but a significantly different crystal packing. Li 2 Mg(NH 2 BH 3 ) 4 thermally dehydrogenates releasing highly pure H 2 in the amount of 7 wt.%, and at a lower temperature then its sodium analogue, making it significantly more viable for practical applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Iron Fortified Complementary Foods Containing a Mixture of Sodium Iron EDTA with Either Ferrous Fumarate or Ferric Pyrophosphate Reduce Iron Deficiency Anemia in 12- to 36-Month-Old Children in a Malaria Endemic Setting: A Secondary Analysis of a Cluster-Randomized Controlled Trial.

PubMed

Glinz, Dominik; Wegmüller, Rita; Ouattara, Mamadou; Diakité, Victorine G; Aaron, Grant J; Hofer, Lorenz; Zimmermann, Michael B; Adiossan, Lukas G; Utzinger, Jürg; N'Goran, Eliézer K; Hurrell, Richard F

2017-07-14

Iron deficiency anemia (IDA) is a major public health problem in sub-Saharan Africa. The efficacy of iron fortification against IDA is uncertain in malaria-endemic settings. The objective of this study was to evaluate the efficacy of a complementary food (CF) fortified with sodium iron EDTA (NaFeEDTA) plus either ferrous fumarate (FeFum) or ferric pyrophosphate (FePP) to combat IDA in preschool-age children in a highly malaria endemic region. This is a secondary analysis of a nine-month cluster-randomized controlled trial conducted in south-central Côte d'Ivoire. 378 children aged 12-36 months were randomly assigned to no food intervention ( n = 125; control group), CF fortified with 2 mg NaFeEDTA plus 3.8 mg FeFum for six days/week ( n = 126; FeFum group), and CF fortified with 2 mg NaFeEDTA and 3.8 mg FePP for six days/week ( n = 127; FePP group). The outcome measures were hemoglobin (Hb), plasma ferritin (PF), iron deficiency (PF < 30 μg/L), and anemia (Hb < 11.0 g/dL). Data were analyzed with random-effect models and PF was adjusted for inflammation. The prevalence of Plasmodium falciparum infection and inflammation during the study were 44-66%, and 57-76%, respectively. There was a significant time by treatment interaction on IDA ( p = 0.028) and a borderline significant time by treatment interaction on iron deficiency with or without anemia ( p = 0.068). IDA prevalence sharply decreased in the FeFum (32.8% to 1.2%, p < 0.001) and FePP group (23.6% to 3.4%, p < 0.001). However, there was no significant time by treatment interaction on Hb or total anemia. These data indicate that, despite the high endemicity of malaria and elevated inflammation biomarkers (C-reactive protein or α-1-acid-glycoprotein), IDA was markedly reduced by provision of iron fortified CF to preschool-age children for 9 months, with no significant differences between a combination of NaFeEDTA with FeFum or NaFeEDTA with FePP. However, there was no overall effect on anemia, suggesting

Three-dimensional structure of phosphoribosyl pyrophosphate synthetase from E. coli at 2.71 Å resolution

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

Timofeev, V. I., E-mail: inna@ns.crys.ras.ru, E-mail: tostars@mail.ru, E-mail: ugama@yandex.ru; Abramchik, Yu. A.; Zhukhlistova, N. E.

2016-01-15

Phosphoribosyl pyrophosphate synthetase from Escherichia coli was cloned, purified, and crystallized. Single crystals of the enzyme were grown under microgravity. The X-ray diffraction data set was collected at the Spring-8 synchrotron facility and used to determine the three-dimensional structure of the enzyme by the molecular-replacement method at 2.71 Å resolution. The active and regulatory sites in the molecule of E. coli phosphoribosyl pyrophosphate synthetase were revealed by comparison with the homologous protein from Bacillus subtilis, the structure of which was determined in a complex with functional ligands. The conformations of polypeptide-chain fragments surrounding and composing the active and regulatory sitesmore » were shown to be identical in both proteins.« less

Transition metals and water-soluble ions in deposits on a building and their potential catalysis of stone decay

NASA Astrophysics Data System (ADS)

McAlister, J. J.; Smith, B. J.; Török, A.

Atmospheric particulates (dust) deposited on buildings are a complex chemical and mineralogical mixture including transition metal oxide matrices that act as a significant medium for further surface reactions and provide efficient sinks for pollutants, especially in urban environments. Once deposited, their transformation by reaction with specific and often highly localised environmental conditions across building facades is related to their degree of exposure to rain-wash. These transformations are central to the soiling of buildings and the availability of salts that lead to stone decay. To investigate these relationships, samples were collected at high and low elevations and under highly and moderately sheltered conditions from a building located on a busy arterial route in Budapest. Selective extraction analysis highlights the mobility/availability of Fe, Mn, Zn, Cu, Cr, Pb and Ni, plus water-soluble Ca 2+, Mg 2+, Na +, K +, Cl -, SO 42- and NO 3- and their potential to take part in surface reactions that could enhance stone decay. Concentrations of water-soluble Fe, Mn and Zn in sheltered dust reach 126 mg kg -1, 80 mg kg -1 and 220 mg kg -1 respectively and under acidic environmental conditions and high humidity, similar levels of Mn and significantly higher concentrations of Fe, Zn, Cu and Pb may be released from the exchangeable/carbonate phase making these metals potentially available to catalyse surface reactions. Sulphate and nitrate coatings plus sufficient moisture increase metal solubility and active sites may be regenerated allowing mobile transition metals to become available and possibly catalyse further surface reactions.

The effect of change in pH on the solubility of iron bis-glycinate chelate and other iron compounds.

PubMed

García-Casal, M N; Layrisse, M

2001-03-01

The effect of a pH change from 2 to 6 was tested on the solubility of ferrous sulfate, ferrous fumarate, iron bis-glycine chelate (Ferrochel) and sodium-iron ethylenediaminetetraacetic acid (NaFeEDTA). It was found that at pH 2 ferrous sulfate, Ferrochel and NaFeEDTA were completely soluble and only 75% of iron from ferrous fumarate was soluble. When pH was raised to 6, iron from amino acid chelate and NaFeEDTA remained completely soluble while solubility from ferrous sulfate and ferrous fumarate decreased 64 and 74%, respectively compared to the amount of iron initially soluble at pH 2. These results suggest that iron solubility from iron bis-glycine chelate and NaFeEDTA is not affected by pH changes within the ranges tested, probably because iron remained associated to the respective compounds.

A method of calculating quartz solubilities in aqueous sodium chloride solutions

USGS Publications Warehouse

Fournier, R.O.

1983-01-01

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm3 of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, pe, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na+ as water of hydration. Generally, the hydration of water correction is negligible. The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting pe, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H2. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water. The average hydration number per molecule of dissolved SiO2 in liquid water and NaCl solutions decreases from about 2.4 at 200??C to about 2.1 at 350??C. This suggests that H4SiO4 may be the dominant aqueous silica species at 350??C, but other

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

NASA Astrophysics Data System (ADS)

Marion, Giles M.; Farren, Ronald E.

1999-05-01

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

The Solubility of Microcrystalline Cellulose in Sodium Hydroxide Solution Is Inconsistent with International Specifications.

PubMed

Kodama, Hanayo; Tamura, Yoshinaga; Kamei, Ichiro; Sato, Kyoko; Akiyama, Hiroshi

2017-01-01

Microcrystalline cellulose (MCC) is used globally as an inactive ingredient in food and nutraceutical products and is commonly used as a food additive. To confirm the conformity of MCC to the solubility requirements stipulated in international specifications, the solubilities of commercially available MCC products were tested in sodium hydroxide (NaOH) solution. All of the samples were insoluble in NaOH solution, which is inconsistent with the descriptions provided in international specifications. We also prepared celluloses with different degree of polymerization (DP) values by acid hydrolysis. Celluloses with lower DP were prepared using a three-step process, and their solubilities were tested in NaOH solution. These celluloses were found to be insoluble, which is inconsistent with the descriptions provided in international specifications. The present study suggests that the descriptions of the solubility of the celluloses in NaOH solution found in the current international specifications should be revised.

Response of aluminum solubility to elevated nitrification in soil of a red spruce stand in eastern Maine

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.

1997-01-01

Elevated concentrations of soluble Al can impair tree growth and be toxic to aquatic biota, but effects of acidic deposition on Al solubility in forest soils are only partially understood because of complex interactions with H+ and organic matter. We therefore evaluated Al solubility in two red spruce stands in eastern Maine, one of which received dry (NH4)2SO4 at a rate of 1800 equiv ha-1 yr-1 during 19891995. Samples of soil (Spodosol Oa and Bh horizons) and soil solution were collected on five dates from 1992 to 1995. The treatment elevated nitrification, causing an increase in acid input that led to inorganic Al concentrations of greater than 60 ??mol L-1 in both the Oa and Bh horizons. Solubility of Al was also lower in the Bh horizon of the treated stand than in the reference stand, a response related to higher DOC concentrations in the treated stand. Concentrations of CuCl2 and pyrophosphate-extractable Al were higher in the Oa horizon of the treated watershed than the reference stand, a result of accelerated weathering of mineral particles caused by lower solution pH in the treated stand (3.47) than in the reference stand (3.69). Dissolved Al concentrations in these soils are the result of complex mechanisms through which mineral matter, organic matter, and pH interact to control Al solubility; mechanisms that are not incorporated in current Al solubility models.

Experimental determination of the solubility product of dolomite at 50-253 °C

NASA Astrophysics Data System (ADS)

Bénézeth, Pascale; Berninger, Ulf-Niklas; Bovet, Nicolas; Schott, Jacques; Oelkers, Eric H.

2018-03-01

The 'dolomite problem', the scarcity of present-day dolomite formation near the Earth's surface, has attracted much attention over the past century. Solving this problem requires having reliable data on the stability and kinetics of formation of this mineral. Toward this goal, the solubility of natural dolomite (CaMg(CO3)2) has been measured from 50 to 253 °C in 0.1 mol/kg NaCl solutions using a hydrogen electrode concentration cell (HECC). The obtained apparent solubility products (Kapp-sp-dol), for the reaction: CaMg(CO3)2 = Ca2+ + Mg2+ + 2CO32-, were extrapolated to infinite dilution to generate the solubility product constants for this reaction (Ksp°-dol). The derived equilibrium constants were fit and can be accurately described by log10Ksp°-dol = a + b/T (K) + cT (K) where a = 17.502, b = -4220.119 and c = -0.0689. This equation and its first and second derivatives with respect to T were used together with corresponding aqueous species properties to calculate the revised standard state thermodynamic properties of dolomite at 25 °C and 1 bar, yielding a Gibbs energy of formation (Δf G298.15∘) equal to -2160.9 ± 2 kJ/mol, (log10Ksp°-dol = -17.19 ± 0.3); an enthalpy of formation (Δf H298.15∘) of -2323.1 ± 2 kJ/mol, an entropy (S298.15∘) of 156.9 ± 2 J/mol/K and heat capacity (Cp298.15∘) of 154.2 ± 2 J/mol/K (uncertainties are 3σ). The dolomite solubility product derived in this study is nearly identical to that computed using SUPCRT92 (Johnson et al., 1992) at 200 °C, but about one order of magnitude higher at 50 and 25 °C, suggesting that dolomite may be somewhat less stable than previously assumed at ambient temperatures.

The Effects of Acetate Buffer Concentration on Lysozyme Solubility

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Pusey, Marc L.

1996-01-01

The micro-solubility column technique was employed to systematically investigate the effects of buffer concentration on tetragonal lysozyme solubility. While keeping the NaCl concentrations constant at 2%, 3%, 4%, 5% and 7%, and the pH at 4.0, we have studied the solubility of tetragonal lysozyme over an acetate buffer concentration range of 0.01M to 0.5M as a function of temperature. The lysozyme solubility decreased with increasing acetate concentration from 0.01M to 0.1M. This decrease may simply be due to the net increase in solvent ionic strength. Increasing the acetate concentration beyond 0.1M resulted in an increase in the lysozyme solubility, which reached a peak at - 0.3M acetate concentration. This increase was believed to be due to the increased binding of acetate to the anionic binding sites of lysozyme, preventing their occupation by chloride. In keeping with the previously observed reversal of the Hoffmeister series for effectiveness of anions in crystallizing lysozyme, acetate would be a less effective precipitant than chloride. Further increasing the acetate concentration beyond 0.3M resulted in a subsequent gradual decrease in the lysozyme solubility at all NaCl concentrations.

The behaviour of myo-inositol hexakisphosphate in the presence of magnesium(II) and calcium(II): protein-free soluble InsP6 is limited to 49 microM under cytosolic/nuclear conditions.

PubMed

Veiga, Nicolás; Torres, Julia; Domínguez, Sixto; Mederos, Alfredo; Irvine, Robin F; Díaz, Alvaro; Kremer, Carlos

2006-11-01

Progress in the biology of myo-inositol hexakisphosphate (InsP(6)) has been delayed by the lack of a quantitative description of its multiple interactions with divalent cations. Our recent initial description of these [J. Torres, S. Dominguez, M.F. Cerda, G. Obal, A. Mederos, R.F. Irvine, A. Diaz, C. Kremer, J. Inorg. Biochem. 99 (2005) 828-840] predicted that under cytosolic/nuclear conditions, protein-free soluble InsP(6) occurs as Mg(5)(H(2)L), a neutral complex that exists thanks to a significant, but undefined, window of solubility displayed by solid Mg(5)(H(2)L).22H(2)O (L is fully deprotonated InsP(6)). Here we complete the description of the InsP(6)-Mg(2+)-Ca(2+) system, defining the solubilities of the Mg(2+) and Ca(2+) (Ca(5)(H(2)L).16H(2)O) solids in terms of K(s0)=[M(2+)](5)[H(2)L(10-)], with pK(s0)=32.93 for M=Mg and pK(s0)=39.3 for M=Ca. The concentration of soluble Mg(5)(H(2)L) at 37 degrees C and I=0.15M NaClO(4) is limited to 49muM, yet InsP(6) in mammalian cells may reach 100muM. Any cytosolic/nuclear InsP(6) in excess of 49muM must be protein- or membrane-bound, or as solid Mg(5)(H(2)L).22H(2)O, and any extracellular InsP(6) (e.g. in plasma) is surely protein-bound.

The solubility of quartz in aqueous sodium chloride solution at 350°C and 180 to 500 bars

USGS Publications Warehouse

Fournier, Robert O.; Rosenbauer, Robert J.; Bischoff, James L.

1982-01-01

The solubility of quartz in 2, 3, and 4 molal NaCl was measured at 350°C and pressures ranging from 180 to 500 bars. The molal solubility in each of the salt solutions is greater than that in pure water throughout the measured pressure range, with the ratio of solubility in NaCl solution to solubility in pure water decreasing as pressure is increased. The measured solubilities are significantly higher than solubilities calculated using a simple model in which the water activity in NaCl solutions decreases either in proportion to decreasing vapor pressure of the solution as salinity is increased or in proportion to decreasing mole fraction of water in the solvent.

Label-free electrical detection of pyrophosphate generated from DNA polymerase reactions on field-effect devices.

PubMed

Credo, Grace M; Su, Xing; Wu, Kai; Elibol, Oguz H; Liu, David J; Reddy, Bobby; Tsai, Ta-Wei; Dorvel, Brian R; Daniels, Jonathan S; Bashir, Rashid; Varma, Madoo

2012-03-21

We introduce a label-free approach for sensing polymerase reactions on deoxyribonucleic acid (DNA) using a chelator-modified silicon-on-insulator field-effect transistor (SOI-FET) that exhibits selective and reversible electrical response to pyrophosphate anions. The chemical modification of the sensor surface was designed to include rolling-circle amplification (RCA) DNA colonies for locally enhanced pyrophosphate (PPi) signal generation and sensors with immobilized chelators for capture and surface-sensitive detection of diffusible reaction by-products. While detecting arrays of enzymatic base incorporation reactions is typically accomplished using optical fluorescence or chemiluminescence techniques, our results suggest that it is possible to develop scalable and portable PPi-specific sensors and platforms for broad biomedical applications such as DNA sequencing and microbe detection using surface-sensitive electrical readout techniques.

Aqueous solubility of calcium L-lactate, calcium D-gluconate, and calcium D-lactobionate: importance of complex formation for solubility increase by hydroxycarboxylate mixtures.

PubMed

Vavrusova, Martina; Munk, Merete Bøgelund; Skibsted, Leif H

2013-08-28

Among the calcium hydroxycarboxylates important for cheese quality, D-lactobionate [Ksp = (7.0 ± 0.3) × 10(-3) mol(3) L(-3)] and L-lactate [Ksp = (5.8 ± 0.2) × 10(-3) mol(3) L(-3)] were found more soluble than D-gluconate [Ksp = (7.1 ± 0.2) × 10(-4) mol(3) L(-3)], as indicated by the solubility products determined electrochemically for aqueous 1.0 M NaCl at 25.0 °C. Still, solubility of calcium L-lactate increases by 45% in the presence of 0.50 M sodium D-gluconate and by 37% in the presence of 0.50 M sodium D-lactobionate, while solubility of calcium D-gluconate increases by 66 and 85% in the presence of 0.50 M sodium L-lactate and 0.50 M sodium D-lactobionate, respectively, as determined by complexometric titration. Sodium L-lactate and sodium D-gluconate have only little influence on solubility of calcium D-lactobionate. The increased solubility is described quantitatively by calcium binding to D-gluconate (K1 = 14 ± 3 mol(-1) L) in 1.0 M NaCl at 25 °C, D-lactobionate (K1 = 11 ± 2 mol(-1) L), and L-lactate (K1 = 8 ± 2 mol(-1) L), as indicated by the association constants determined electrochemically. In mixed hydroxycarboxylate solutions, calcium binding is quantitatively described by the geometric mean of the individual association constants for both aqueous 1.0 and 0.20 M NaCl, indicating a 1:1 stoichiometry for complex formation.

High-Capacity Mg-Organic Batteries Based on Nanostructured Rhodizonate Salts Activated by Mg-Li Dual-Salt Electrolyte.

PubMed

Tian, Jing; Cao, Dunping; Zhou, Xuejun; Hu, Jiulin; Huang, Minsong; Li, Chilin

2018-04-24

A magnesium battery is a promising candidate for large-scale transportation and stationary energy storage due to the security, low cost, abundance, and high volumetric energy density of a Mg anode. But there are still some obstacles retarding the wide application of Mg batteries, including poor kinetics of Mg-ion transport in lattices and low theoretical capacity in inorganic frameworks. A Mg-Li dual-salt electrolyte enables kinetic activation by dominant intercalation of Li-ions instead of Mg-ions in cathode lattices without the compromise of a stable Mg anode process. Here we propose a Mg-organic battery based on a renewable rhodizonate salt ( e. g., Na 2 C 6 O 6 ) activated by a Mg-Li dual-salt electrolyte. The nanostructured organic system can achieve a high reversible capacity of 350-400 mAh/g due to the existence of high-density carbonyl groups (C═O) as redox sites. Nanocrystalline Na 2 C 6 O 6 wired by reduced graphene oxide enables a high-rate performance of 200 and 175 mAh/g at 2.5 (5 C) and 5 A/g (10 C), respectively, which also benefits from a high intrinsic diffusion coefficient (10 -12 -10 -11 cm 2 /s) and pesudocapacitance contribution (>60%) of Na 2 C 6 O 6 for Li-Mg co-intercalation. The suppressed exfoliation of C 6 O 6 layers by a firmer non-Li pinning via Na-O-C or Mg-O-C and a dendrite-resistive Mg anode lead to a long-term cycling for at least 600 cycles. Such an extraordinary capacity/rate performance endows the Mg-Na 2 C 6 O 6 system with high energy and power densities up to 525 Wh/kg and 4490 W/kg (based on active cathode material), respectively, exceeding the level of high-voltage insertion cathodes with typical inorganic structures.

Molecular cloning and expression of Chimonanthus praecox farnesyl pyrophosphate synthase gene and its possible involvement in the biosynthesis of floral volatile sesquiterpenoids.

PubMed

Xiang, Lin; Zhao, Kaige; Chen, Longqing

2010-01-01

Farnesyl pyrophosphate (FPP) synthase catalyzes the biosynthesis of FPP, which is the precursors of sesquiterpenoids such as floral scent volatiles, from isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). cDNA encoding wintersweet (Chimonanthus praecox L.) FPP synthase was isolated by the RT-PCR and RACE methods. The deduced amino acid sequence showed a high identity to plant FPP synthases. Expression of the gene in Escherichia coli yielded FPPS activity that catalyzed the synthesis of FPP as a main product. Tissue-specific and developmental analyses of the mRNA levels of CpFPPS and volatile sesquiterpenoids levels in C. praecox flowers revealed that the FPPS may play a regulatory role in floral volatile sesquiterpenoids of wintersweet. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Experimental Work Conducted on MgO Inundated Hydration in WIPP-Relevant Brines

NASA Astrophysics Data System (ADS)

Deng, H.; Xiong, Y.; Nemer, M. B.; Johnsen, S.

2009-12-01

Magnesium oxide (MgO) is being emplaced in the Waste Isolation Pilot Plant (WIPP) as an engineered barrier to mitigate the effect of microbial CO2 generation on actinide mobility in a postclosure repository environment. MgO will sequester CO2 and consume water in brine or water vapor in the gaseous phase. Martin Marietta (MM) MgO is currently being emplaced in the WIPP. A fractional-factorial experiment has been performed to study the inundated-hydration of MM MgO as a function of its particle size, solid-to-liquid ratio, and brine type. MgO hydration experiments have been carried out with three MgO particle sizes and two solid-to-liquid ratios in three WIPP-related brines: ERDA-6, GWB and simplified GWB. ERDA-6 is a synthetic NaCl-rich brine typical of a Castile brine reservoir below the repository. GWB is a synthetic MgCl2- and NaCl-rich brine representative of intergranular brines from the Salado Formation at or near the stratigraphic horizon of the repository. Simplified GWB contains amounts of Mg, Na, and Cl similar to those in GWB without other minor constituents. The hydration products include brucite (Mg(OH)2) and phase 5 (Mg3(OH)5Cl4H2O). In addition to phase 5, MgO hydration in GWB or simplified GWB produces brucite, whereas MgO hydrated in ERDA-6 only produces brucite. The MgO particle size has had a significant effect on the formation of hydration products: small MgO particles have hydrated before the large particles. MgO has hydrated faster in simplified GWB than in the other two brines. In ERDA-6, the solid-to-liquid ratio has affected the brine pH due to the presence of CaO (~1 wt %) as an impurity in MM MgO. GWB has sufficient dissolved Mg to buffer pH despite small amounts of CaO. Both our results and thermodynamic modeling indicate that phase-5 is the stable Mg-OH-Cl phase in Mg-Na-Cl-dominated brines with ionic strengths and chemical compositions similar to that of GWB. In contrast, phase-3 (Mg2(OH)3Cl4H2O) is the stable phase in the MgCl2

Green thermal-assisted synthesis and characterization of novel cellulose-Mg(OH)2 nanocomposite in PEG/NaOH solvent.

PubMed

Ponomarev, Nikolai; Repo, Eveliina; Srivastava, Varsha; Sillanpää, Mika

2017-11-15

Synthesis of nanocomposites was performed using microcrystalline cellulose (MCC), MgCl 2 in PEG/NaOH solvent by a thermal-assisted method at different temperatures by varying time and the amount of MCC. Results of XRD, FTIR, and EDS mapping showed that the materials consisted of only cellulose (CL) and magnesium hydroxide (MH). According to FTIR and XRD, it was found that crystallinity of MH in cellulose nanocomposites is increased with temperature and heating time and decreased with increasing of cellulose amount. The PEG/NaOH solvent has a significant effect on cellulose and Mg(OH) 2 morphology. BET and BJH results demonstrated the effects of temperature and cellulose amount on the pore size corresponding to mesoporous materials. TG and DTG analyses showed the increased thermal stability of cellulose nanocomposites with increasing temperature. TEM and SEM analyses showed an even distribution of MH nanostructures with various morphology in the cellulose matrix. The cellulose presented as the polymer matrix in the nanocomposites. It was supposed the possible interaction between cellulose and Mg(OH) 2 . The novel synthesis method used in this study is feasible, cost-efficient and environmentally friendly. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dietary toxicity of soluble and insoluble molybdenum to northern bobwhite quail (Colinus virginianus).

PubMed

Stafford, Jennifer M; Lambert, Charles E; Zyskowski, Justin A; Engfehr, Cheryl L; Fletcher, Oscar J; Clark, Shanna L; Tiwary, Asheesh; Gulde, Cynthia M; Sample, Bradley E

2016-03-01

Limited data are available on the effects of molybdenum (Mo) on avian wildlife, which impairs evaluation of ecological exposure and risk. While Mo is an essential trace nutrient in birds, little is known of its toxicity to birds exposed to molybdenum disulfide (MoS2), the predominant form found in molybdenite ore. The chemical form and bioavailability of Mo is important in determining its toxicity. Avian toxicity tests typically involve a soluble form of Mo, such as sodium molybdate dihydrate (SMD, Na2MoO4·2H2O); however MoS2 is generally insoluble, with low bioaccessibility under most environmental conditions. The current study monitored survival and general health (body weight and food consumption) of 9-day old northern bobwhite exposed to soluble Mo (SMD) and ore-related Mo (MoS2) in their diet for 30 days. Toxicity and bioavailability (e.g. tissue distribution) of the two Mo forms were compared. Histopathology evaluations and serum, kidney, liver, and bone tissue sample analyses were conducted. Copper, a nutrient integrally associated with Mo toxicity, was also measured in the diet and tissue. No treatment-related mortality occurred and no treatment-related lesions were recorded for either Mo form. Tissue analyses detected increased Mo concentrations in serum, kidney, liver, and bone tissues following exposure to SMD, with decreasing concentrations following a post-exposure period. For the soluble form, a No-Observed-Adverse-Effect Concentration (NOAEC) of 1200 mg Mo as SMD/kg feed (134 mg SMD/kg body weight/day) was identified based on body weight and food consumption. No adverse effects were observed in birds exposed to MoS2 at the maximum dose of 5000 mg MoS2/kg feed (545 mg MoS2/kg body weight/day). These results show that effects associated with MoS2, the more environmentally prevalent and less bioavailable Mo form, are much less than those observed for SMD. These data should support more realistic representations of exposure and risks to avian receptors

The Thiamine-Pyrophosphate-Motif

NASA Technical Reports Server (NTRS)

Ciszak, Ewa; Dominiak, Paulina

2004-01-01

Thiamin pyrophosphate (TPP), a derivative of vitamin B1, is a cofactor for enzymes performing catalysis in pathways of energy production including the well known decarboxylation of a-keto acid dehydrogenases followed by transketolation. TPP-dependent enzymes constitute a structurally and functionally diverse group exhibiting multimeric subunit organization, multiple domains and two chemically equivalent catalytic centers. Annotation of functional TPP-dependcnt enzymes, therefore, has not been trivial due to low sequence similarity related to this complex organization. Our approach to analysis of structures of known TPP-dependent enzymes reveals for the first time features common to this group, which we have termed the TPP-motif. The TPP-motif consists of specific spatial arrangements of structural elements and their specific contacts to provide for a flip-flop, or alternate site, enzymatic mechanism of action. Analysis of structural elements entrained in the flip-flop action displayed by TPP-dependent enzymes reveals a novel definition of the common amino acid sequences. These sequences allow for annotation of TPP-dependent enzymes, thus advancing functional proteomics. Further details of three-dimensional structures of TPP-dependent enzymes will be discussed.

Solubility and modeling acid-base properties of adrenaline in NaCl aqueous solutions at different ionic strengths and temperatures.

PubMed

Bretti, Clemente; Cigala, Rosalia Maria; Crea, Francesco; De Stefano, Concetta; Vianelli, Giuseppina

2015-10-12

Solubility and acid-base properties of adrenaline were studied in NaCl aqueous solutions at different ionic strengths (0solubility of the ligand was calculated from simple mass balance equations, by using the free hydrogen concentration and the protonation constants of the ligand determined in the same experimental conditions of the solubility measurements. The salting-In or Out parameters and the activity coefficient of the neutral species were calculated by means of the Setschenow equation. The dependence of the protonation constants on the ionic strength was modeled by means of the Debye-Hückel type equation and of the SIT (Specific ion Interaction Theory) approach. The specific interaction parameters of the ion pairs were also reported. For the protonation constants, the following thermodynamic values at infinite dilution were obtained: T=298.15 K, logK1(H0)=10.674±0.018 and logK2(H0)=8.954±0.022; T=310.15K, logK1(H0)=10.355±0.018 and logK2(H0)=8.749±0.030. Copyright © 2015 Elsevier B.V. All rights reserved.