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1

[Immobilization technology and mechanism of fly ash using H3PO4].  

PubMed

Chemical composition and toxicity leaching characteristics of fly ash was analyzed. The experiment results show that many heavy metals were contained; leaching concentration of Pb is 67.03 mg/L, which exceeds the limit of identification standard for hazardous wastes. Effect of input mass of H3PO4 on immobilization of heavy metals and its long-term environmental stability was studied. The results show that when input 8% - 14% (H3PO4 mass/ fly ash mass) of H3PO4 sound immobilization effect can be achieved; 8% and 12% of H3PO4 will bring a satisfactory environmental stability of heavy metals, while more H3PO4 led to less buffer capacity to acid conditions. In fly ash treated by 12% H3PO4, a small quantity of crystal Cr2P2O7, ZnP2, Pb3P4O13, Pb3P2O7, NaZnPO4, NaPbP3O9, Ca2ZnSi2O7 can be detected by XRD; many independent fly ash particles and bar-shaped Pb5 (PO4)3Cl with a diameter of 0.3 - 0.5 microm were observed by SEM; concentrated heavy metal materials were not obtained by CHBr3 floatation. Conclusions can be drawn that, through neutralization reaction of H3PO4 with strongly alkaline fly ash, stabilization reaction conditions were improved, entrapped heavy metals were chemically activated and PO4(3-) needed in stabilization was produced. Activated heavy metals combined with PO4(3-) on surface of fly ash,generated phosphates existing as forms of solid solution in SiO2, CaCO3, CaSO4, KCl, NaCl. PMID:17111636

Wang, Jun; Jiang, Jian-Guo; Sui, Ji-Chao; Yang, Shi-Jian

2006-08-01

2

New molecular crystals with nonlinear optical properties: 3-aminophenol-H 3PO 4 and 4-aminophenol-H 3PO 4  

NASA Astrophysics Data System (ADS)

The crystal structures of the 3-aminophenol-H 3PO 4 (3-amphph) and 4-aminophenol-H 3PO 4 (4-amphph) complexes were determined at 100 K. They both belong to the P2 12 12 1 space group of the orthorhombic system with Z=4. The lattice parameters for the 3-amphph crystal are a=4.493(2) Å, b=9.750(3) Å and c=18.328(4) Å and those for the 4-amphph crystal are a=6.116(2) Å, b=7.496(2) Å and c=18.739(4) Å. The SHG powder efficiencies relative to KDP were 0.86 for 3-amphph and 0.50 for 4-amphph, measured at 1064 nm using the Kurtz-Perry method. The infrared powder spectra of both complexes were obtained and the hydrogen bond vibrations are discussed.

G?owiak, Tadeusz; Debrus, Solange; May, Marie; Barnes, Austin J.; Ratajczak, Henryk

2001-09-01

3

Interaction model for the volumetric properties of weak electrolytes with application to H 3 PO 4  

Microsoft Academic Search

The Pitzer ion-interaction model for the thermodynamic properties of a weakly dissociating neutral solute is extended to include solution densities and compressibilities. Excellent agreement is obtained with the literature data for pure aqueous phosphoric acid to 8m. The first and second pressure derivatives of the interaction parameters for H+, H2PO4-, and H3PO4 are evaluated, in addition to the limiting partial

Leslie Barta; Daniel J. Bradley

1983-01-01

4

Inhibition of steel corrosion in 2 M H 3PO 4 by artemisia oil  

Microsoft Academic Search

Artemisia oil (Ar) is extracted from artemisia herba alba collected in Ain es-sefra-Algeria, and tested as corrosion inhibitor of steel in 2M H3PO4 using weight loss measurements, electrochemical polarisation and EIS methods. The naturally oil reduces the corrosion rate. The inhibition efficiency was found to increase with oil content to attain 79% at 6g\\/l. Ar acts as a cathodic inhibitor.

M. Benabdellah; M. Benkaddour; B. Hammouti; M. Bendahhou; A. Aouniti

2006-01-01

5

CO electrooxidation study on Pt and Pt-Ru in H3PO4 using MEA with PBI-H3PO4 membrane  

NASA Astrophysics Data System (ADS)

CO electrooxidation on Pt and Pt-Ru in H3PO4 was studied in the temperature range 120-180 °C using CO-N2-H2O gas mixtures of controlled composition. On Pt and Pt-Ru the voltammetry curves exhibited Tafel behavior in a wide potential range with a slope of 80-100 mV per decade. Replacement of Pt with Pt-Ru on the anode resulted mainly in a shift of CO electrooxidation voltammetry curves by approx. -0.3 V. Reaction order in respect to water vapor pressure was found close to unity with both electrocatalysts. Reaction order in respect to CO partial pressure was found negative, close to zero. Values of apparent activation energy of CO electrooxidation on these electrocatalysts were nearly equal, Ea app = 110 ± 15 kJ mol-1. The results were interpreted within the framework of Langmuir-Hinshelwood mechanism. An equation, which describes the observed features of CO electrooxidation on Pt and Pt-Ru, was suggested. Comparing results of the present study with results of earlier studies of CO tolerance of Pt and Pt-Ru electrocatalysts, it was concluded that CO electrooxidation can hardly play a significant role in CO tolerance of PEM FC with PBI-PA membranes.

Modestov, A. D.; Tarasevich, M. R.; Leykin, A. Y.

2011-03-01

6

A novel H 3PO 4\\/Nafion–PBI composite membrane for enhanced durability of high temperature PEM fuel cells  

Microsoft Academic Search

A novel phosphoric acid doped Nafion–polybenzimidazole (H3PO4\\/Nafion–PBI) composite membrane was prepared and the H2\\/O2 single cell durability was tested at 150°C without humidification. The durability was improved 55% compared with that of phosphoric acid doped polybenzimidazole (H3PO4\\/PBI). During the durability test, the hydrogen permeability of the membrane and the internal resistance of the single cell were detected using linear sweep

Yunfeng Zhai; Huamin Zhang; Yu Zhang; Danmin Xing

2007-01-01

7

Preparation and characterization of activated carbon from reedy grass leaves by chemical activation with H3PO4  

NASA Astrophysics Data System (ADS)

Activated carbons were produced from reedy grass leaves by chemical activation with H3PO4 in N2 atmosphere and their characteristics were investigated. The effects of activation temperature and time were examined. Adsorption capacity was demonstrated with BET and iodine number. Micropore volume and pore size distribution of activated carbons were characterized by N2 adsorption isotherms. The surface area and iodine number of the activated carbons produced at 500 °C for 2 h were 1474 m2/g and 1128 mg/g, respectively. Thermal decomposition of pure reedy grass leaves and H3PO4-impregnated reedy grass leaves have been investigated with thermogravimetric/mass spectroscopy (TG-MS) technique. It was found that the temperature and intensity of maximum evolution of H2O and CO2 of H3PO4-impregnated reedy grass leaves were lower than that of pure reedy grass leaves. This implies that H3PO4 as an activating reagent changed the thermal degradation of the reedy grass leaves, stabilized the cellulose structure, leading to a subsequent change in the evolution of porosity. The results of X-ray photoelectron spectroscopy and Fourier-infrared spectroscopy analysis indicate that the produced activated carbons have rich functional groups on surface.

Xu, Jianzhong; Chen, Lingzhi; Qu, Hongqiang; Jiao, Yunhong; Xie, Jixing; Xing, Guangen

2014-11-01

8

Standard Thermodynamic Properties of H 3 PO 4 (aq) over a Wide Range of Temperatures and Pressures  

Microsoft Academic Search

The densities and heat capacities of solutions of phosphoric acid, 0.05 to 1 mol kg -1, were measured using flow vibrating tube densitometry and differential Picker-type calorimetry at temperatures up to 623 K and at pressures up to 28 MPa. The standard molar volumes and heat capacities of molecular H3PO4(aq) were obtained, via the apparent molar properties corrected for partial

Karine Ballerat-Busserolles; Josef Sedlbauer; Vladimir Majer

2007-01-01

9

Characterization of H3PO4-Treated Rice Husk Adsorbent and Adsorption of Copper(II) from Aqueous Solution  

PubMed Central

Rice husk, a surplus agricultural byproduct, was applied to the sorption of copper from aqueous solutions. Chemical modifications by treating rice husk with H3PO4 increased the sorption ability of rice husk for Cu(II). This work investigated the sorption characteristics for Cu(II) and examined the optimum conditions of the sorption processes. The elemental compositions of native rice husk and H3PO4-treated rice husk were determined by X-ray fluorescence (XRF) analysis. The scanning electron microscopic (SEM) analysis was carried out for structural and morphological characteristics of H3PO4-treated rice husk. The surface functional groups (i.e., carbonyl, carboxyl, and hydroxyl) of adsorbent were examined by Fourier Transform Infrared Technique (FT-IR) and contributed to the adsorption for Cu(II). Adsorption isotherm experiments were carried out at room temperature and the data obtained from batch studies fitted well with the Langmuir and Freundlich models with R2 of 0.999 and 0.9303, respectively. The maximum sorption amount was 17.0358?mg/g at a dosage of 2?g/L after 180?min. The results showed that optimum pH was attained at pH 4.0. The equilibrium data was well represented by the pseudo-second-order kinetics. The percentage removal for Cu(II) approached equilibrium at 180?min with 88.9% removal. PMID:24678507

Zheng, Ru; Zhao, Jiaying; Ma, Fang; Zhang, Yingchao; Meng, Qingjuan

2014-01-01

10

Standard thermodynamic properties of H3PO4(aq) over a wide range of temperatures and pressures.  

PubMed

The densities and heat capacities of solutions of phosphoric acid, 0.05 to 1 mol kg-1, were measured using flow vibrating tube densitometry and differential Picker-type calorimetry at temperatures up to 623 K and at pressures up to 28 MPa. The standard molar volumes and heat capacities of molecular H3PO4(aq) were obtained, via the apparent molar properties corrected for partial dissociation, by extrapolation to infinite dilution. The data on standard derivative properties were correlated simultaneously with the dissociation constants of phosphoric acid from the literature using the theoretically founded SOCW model. This made it possible to describe the standard thermodynamic properties, particularly the standard chemical potential, of both molecular and ionized phosphoric acid at temperatures up to at least 623 K and at pressures up to 200 MPa. This representation allows one to easily calculate the first-degree dissociation constant of H3PO4(aq). The performance of the SOCW model was compared with the other approaches for calculating the high-temperature dissociation constant of the phosphoric acid. Using the standard derivative properties, sensitively reflecting the interactions between the solute and the solvent, the high-temperature behavior of H3PO4(aq) is compared with that of other weak acids. PMID:17201442

Ballerat-Busserolles, Karine; Sedlbauer, Josef; Majer, Vladimir

2007-01-11

11

Characterization of H3PO4-treated rice husk adsorbent and adsorption of copper(II) from aqueous solution.  

PubMed

Rice husk, a surplus agricultural byproduct, was applied to the sorption of copper from aqueous solutions. Chemical modifications by treating rice husk with H3PO4 increased the sorption ability of rice husk for Cu(II). This work investigated the sorption characteristics for Cu(II) and examined the optimum conditions of the sorption processes. The elemental compositions of native rice husk and H3PO4-treated rice husk were determined by X-ray fluorescence (XRF) analysis. The scanning electron microscopic (SEM) analysis was carried out for structural and morphological characteristics of H3PO4-treated rice husk. The surface functional groups (i.e., carbonyl, carboxyl, and hydroxyl) of adsorbent were examined by Fourier Transform Infrared Technique (FT-IR) and contributed to the adsorption for Cu(II). Adsorption isotherm experiments were carried out at room temperature and the data obtained from batch studies fitted well with the Langmuir and Freundlich models with R (2) of 0.999 and 0.9303, respectively. The maximum sorption amount was 17.0358 mg/g at a dosage of 2 g/L after 180 min. The results showed that optimum pH was attained at pH 4.0. The equilibrium data was well represented by the pseudo-second-order kinetics. The percentage removal for Cu(II) approached equilibrium at 180 min with 88.9% removal. PMID:24678507

Zhang, Ying; Zheng, Ru; Zhao, Jiaying; Ma, Fang; Zhang, Yingchao; Meng, Qingjuan

2014-01-01

12

Influence of HNO3/H3PO4-NANO2 mediated oxidation on the structure and properties of cellulose fibers.  

PubMed

The bamboo pulp cellulose fiber was oxidized with HNO3/H3PO4-NaNO2 mixture to obtain oxidized cellulose containing different levels of carboxyl content and with high yields. The effects of HNO3/H3PO4-NaNO2 mediated oxidation on structure and properties of the fiber were investigated. The results showed that an increase in carboxyl content and weight loss of oxidized fibers appeared with increasing oxidation time. Compared with the original cellulose, the oxidized fibers had lower crystallinity (29-40%) and thermal stability. The patterns of (13)C NMR, X-ray diffraction and other testing methods revealed that the oxidation mostly occurred at C6 primary hydroxyl groups of cellulose. Moreover, an oxidized fiber with 94.14-98.59% of high yields and 1.13-3.56% of carboxyl content was obtained in the range of oxidation time from 15 to 60 min, while its mechanical properties did not change significantly. This work presented some detailed information about structure-property correlations of oxidized bamboo pulp cellulose fibers and was useful in planning applications of these products. PMID:25037436

Xu, Yunhui; Liu, Xin; Liu, Xuelan; Tan, Jiulong; Zhu, Hongling

2014-10-13

13

Preparation and textural characterisation of activated carbon from vine shoots ( Vitis vinifera) by H 3PO 4—Chemical activation  

NASA Astrophysics Data System (ADS)

An abundant and low-cost agricultural waste as vine shoots ( Vitis vinifera) (VS), which is generated by the annual pruning of vineyards, has been used as raw material in the preparation of powder activated carbon (AC) by the method of chemical activation with phosphoric acid. After size reduction, VS were impregnated for 2 h with 60 wt.% H 3PO 4 solution at room temperature, 50 and 85 °C. The three impregnated products were carbonised at 400 °C. The product impregnated at 50 °C was heated either first at 150-250 °C and then at 400 °C or simply at 350-550 °C in N 2 atmosphere. The time of isothermal treatment after each dynamic heating was 2 h. The carbons were texturally characterised by gas adsorption (N 2, -196 °C), mercury porosimetry, and density measurements. FT-IR spectroscopy was also applied. Better developments of surface area and microporosity are obtained when the impregnation of VS with the H 3PO 4 solution is effected at 50 °C and for the products heated isothermally at 200 and 450 °C. The mesopore volume is also usually higher for the products impregnated and heated at intermediate temperatures.

Corcho-Corral, B.; Olivares-Marín, M.; Fernández-González, C.; Gómez-Serrano, V.; Macías-García, A.

2006-06-01

14

Systematic characterization of a PBI/H3PO4 sol-gel membrane-Modeling and simulation  

NASA Astrophysics Data System (ADS)

This work presents a three-dimensional, steady-state, non-isothermal model of a high-temperature polymer-electrolyte-membrane fuel cell (HTPEMFC) using a phosphoric acid-doped polybenzimidazole (PBI/H3PO4) sol-gel membrane. The model accounts for the gold-plated copper current collector plates, the bipolar plates, all gas flow channels (flow-field), the gas diffusion layers, the reaction layers, and the membrane. Electrochemical reactions are modeled using an agglomerate approach and include the gas diffusivity and the gas solubility. The conductivity of the membrane is modeled using the Arrhenius equation to describe the temperature dependence. Finite elements are used to discretize all computational subdomains, and a commercially available code is used to solve the problem. The predicted values are compared to typical operating conditions, and a good agreement is found. The current density, the solid- and fluid-(gas)-phase temperatures and other quantities are analyzed throughout the computational subdomains. It was observed that the Arrhenius approach is valid in a certain temperature range and may overpredict the PBI/H3PO4 sol-gel membrane conductivity at higher solid-phase temperatures. Moreover, it is shown how the fluid-(gas)-phase temperature influences the solid-phase temperature and the current density distribution. Concrete values are deduced from the simulations and discussed according to experimental test.

Siegel, C.; Bandlamudi, G.; Heinzel, A.

2011-03-01

15

Solid state 31P MAS NMR spectroscopy and conductivity measurements on NbOPO4 and H3PO4 composite materials  

NASA Astrophysics Data System (ADS)

A systematic study of composite powders of niobium oxide phosphate (NbOPO4) and phosphoric acid (H3PO4) has been performed in order to characterize the material's ability to perform as an electrolyte material in medium temperature fuel cells and electrolyzers. Powders of H3PO4 contents between 13.1 and 74.2 M% were produced and characterized with powder X-ray diffraction, 31P MAS NMR and impedance spectroscopy. NMR revealed that a significant degree of dehydration and vaporization of H3PO4 takes place above 200 °C, and increases with temperature. At 500 °C the NbOPO4 and H3PO4 has reacted to form niobium pyrophosphate (Nb2P4O15). Impedance spectroscopy showed an increase in conductivity with increasing acid concentration, whereas the conductivity decreased slightly with increasing temperature. The highest conductivity measured was 2.5·10-3 S/cm for a sample containing 74.2 M% of H3PO4. Lastly, it was shown that NbOPO4 has no significant conductivity of its own.

Risskov Sørensen, Daniel; Nielsen, Ulla Gro; Skou, Eivind M.

2014-11-01

16

Improvement in the etching performance of the acrylonitrile-butadiene-styrene resin by MnO2-H3PO4-H2SO4 colloid.  

PubMed

The present study aimed to evaluate the surface etching of the acrylonitrile-butadiene-styrene (ABS) resin in the MnO2-H3PO4-H2SO4 colloid. To enhance the soluble Mn(IV) ion concentration and improve the etching performance of ABS resin, H3PO4 was added as a complexing agent into the MnO2-H2SO4 etching system. The effects of the H2SO4 concentration and etching time on the surface topography, surface roughness, adhesion strength, and the surface chemistry of the ABS substrates were investigated. The optimal oxidation potentials of MnO2 in the colloids decreased from 1.426 to 1.369 V with the addition of H3PO4. Though the etching conditions changed from 70 °C for 20 min to 60 °C for 10 min, the adhesion strength between the ABS substrates and electroless copper film increased from 1.19 to 1.33 KN/m after etching treatment. This could be attributed to the significant increase of the soluble Mn(IV) ion concentration in the MnO2-H3PO4-H2SO4 colloid. The surface chemistry results demonstrated that the oxidation reaction of -C?C- bonds in the polybutadiene phase was accelerated in the etching process by the addition of H3PO4, and the abundant -COOH and -OH groups were formed rapidly on the ABS surface with the etching treatment. These results were in agreement with the results of surface scanning electron microscopic observations and adhesion strength measurement. The results suggested that the MnO2-H3PO4-H2SO4 colloid was an effective surface etching system for the ABS surface roughness. PMID:23611532

Zhao, Wenxia; Ding, Jie; Wang, Zenglin

2013-05-21

17

Studies on the identification of the heteropoly acid generated in the H 3PO 4–WO 3–Nb 2O 5 catalyst and its thermal transformation process  

Microsoft Academic Search

The precursor of the mixed metal oxide catalyst composed of H3PO4–WO3–Nb2O5, which exhibits excellent activity in Friedel–Crafts alkylations, was identified with 31P NMR. It was revealed that the Keggin-type mixed heteropoly acid, H4PNbW11O40, was spontaneously generated during preparation of the H3PO4–WO3–Nb2O5 catalyst. The partial decomposition of H4PNbW11O40 occurred in the temperature range of 673–823 K to give an amorphous oxide

Kazu Okumura; Katsuhiko Yamashita; Kazuhiro Yamada; Miki Niwa

2007-01-01

18

TECHNICAL NOTE: Preparation and characterization of activated carbons made up from different woods by chemical activation with H3PO4  

NASA Astrophysics Data System (ADS)

There are many known methods for the preparation of activated carbons. They are often classified as chemical and physical activation methods, a division widely used in the scientific literature. In this paper we study the preparation of activated carbons from different woods (chestnut, cedarwood, walnut) by chemical activation with different concentrations of phosphoric acid (36 and 85 wt%). The prepared activated carbons were characterized by the following techniques: physical adsorption of gases, mercury porosimetry, chemical analysis and measurement of density by helium and mercury displacement. The main conclusion obtained was that chemical activation with 36 wt% H3PO4 yields activated carbons with better textural properties than those prepared with 85 wt% H3PO4. The effects of activation on the textural properties of the activated carbons improve when the concentration of phosphoric acid is reduced.

Macías-García, A.; Díaz-Díez, M. A.; Gómez-Serrano, V.; Fernández González, M. C.

2003-12-01

19

Synergistic inhibition effect of 6-benzylaminopurine and iodide ion on the corrosion of cold rolled steel in H 3PO 4 solution  

Microsoft Academic Search

The synergistic inhibition effect of 6-benzylaminopurine (BAP) and iodide ion (I?) on the corrosion of cold rolled steel (CRS) in 1.0M H3PO4 solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) methods. The results show that BAP has a moderate inhibitive effect. However, incorporation of BAP with I? improves the inhibition performance significantly. The adsorption

Xianghong Li; Shuduan Deng; Hui Fu

2011-01-01

20

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal  

NASA Astrophysics Data System (ADS)

A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ?G and positive ?H. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-10-01

21

Investigation of the inhibitive effect of triphenyltin 2-thiophene carboxylate on corrosion of steel in 2 M H 3PO 4 solutions  

NASA Astrophysics Data System (ADS)

A new organic compound was synthesised and tested as corrosion inhibitor of steel in phosphoric acid medium using gravimetric, electrochemical polarisation and electrochemical impedance spectroscopy (EIS) measurements. Results obtained show that the inhibitor studied is a good cathodic inhibitor. EIS results show that the change in the impedance parameters ( RT and Cdl) with concentration of triphenyltin 2-thiophene carboxylate (TTC) is indicative of the adsorption of molecules leading to the formation of a protective layer on the surface of steel. The effect of the temperature on the steel corrosion in 2 M H 3PO 4 and with addition of various concentrations of TTC in the range of temperature 298-348 K was studied. The associated apparent activation corrosion energy has been determined.

Benabdellah, M.; Aouniti, A.; Dafali, A.; Hammouti, B.; Benkaddour, M.; Yahyi, A.; Ettouhami, A.

2006-09-01

22

Dye removal of activated carbons prepared from NaOH-pretreated rice husks by low-temperature solution-processed carbonization and H3PO4 activation.  

PubMed

A coupling of low-temperature sulfuric acid-assisted carbonization and H3PO4 activation was employed to convert NaOH-pretreated rice husks into activated carbons with extremely high surface area (2028 m(2) g(-1)) and integrated characteristics. The influences of the activation temperature and impregnation ratio on the surface area, pore volume of activated carbons were thoroughly investigated. The morphology and surface chemistry of activated carbons were characterized using N2 sorption, FTIR, XPS, SEM, TEM, etc. The adsorption capacity of resulting carbons obtained under optimum preparation conditions was systematically evaluated using methylene blue under various simulated conditions. The adsorption process can be well described by both Langmuir isotherm model and the pseudo-second order kinetics models; and the maximum monolayer capacity of methylene blue was ca. 578 mg g(-1). PMID:23892148

Chen, Yun; Zhai, Shang-Ru; Liu, Na; Song, Yu; An, Qing-Da; Song, Xiao-Wei

2013-09-01

23

Reduction of interpore distance of anodized aluminum oxide nano pattern by mixed H3PO4:H2SO4 electrolyte.  

PubMed

A self-formed and ordered anodized aluminum oxide (AAO) nano pattern has generated considerable interest in both scientific research and commercial application. However, the interpore distance obtainable by AAO is limited by 40-500 nm depending on electrolyte and anodizing voltage. It's believed that below-30 nm AAO pattern is a key technology in the fabrication semiconductor nano structures with enhanced quantum confinement effect, so we worked on the reduction of interpore distance of AAO with a novel electrolyte. AAO nano patterns were fabricated with mixed H2SO4 and H3PO4 as an electrolyte for various voltages and temperatures. The interpore distance and pore diameter of AAO were decreased with reduced anodizing voltage. As a result, an AAO nano pattern with the interpore distance of 27 nm and the pore diameter of 7 nm was obtained. This is the smallest pattern, as long as we know, reported till now with AAO technique. The fabricated AAO pattern could be utilized for uniform and high density quantum dots with increased quantum effect. PMID:18047152

Song, Kwang Min; Park, Joonmo; Ryu, Sang-Wan

2007-11-01

24

Structure-property interplay of proton conducting membranes based on PBI5N, SiO2-Im and H3PO4 for high temperature fuel cells.  

PubMed

Polybenzimidazoles (PBIs) are among the polymers of choice to prepare membranes for high temperature polymer fuel cells. Poly-2,2'(2,6-pyridine)-5,5'-bibenzimidazole (PBI5N), doped with H(3)PO(4), and acid-doped PBI5N containing 10 wt% of imidazole-functionalized silica membranes were studied with thermogravimetric analysis, differential scanning calorimetry, dynamic-mechanical analysis, infrared spectroscopy, and broadband electric spectroscopy to examine the structure-property relationships. Key results show that: (1) doped PBI5N membranes show thermal decomposition starting at 120 °C, while pristine PBI5N is stable up to 300 °C; (2) the presence of filler increases the acid uptake and decreases the crystallinity of PBI5N; (3) the addition of phosphoric acid reduces the mechanical properties of the membrane, while the addition of filler has the opposite effect; (4) acid-doped membranes have conductivity values on the order of 10(-2)-10(-3) S cm(-1); and (5) membranes exhibit a Vogel-Tamman-Fulcher (VTF) type proton conduction mechanism, where proton hopping is coupled with the segmental motion of the polymer chain. Infrared spectroscopy combined with DFT quantum mechanical calculations was used to assign the experimental spectrum of PBI5N. PMID:21594297

Di Noto, Vito; Piga, Matteo; Giffin, Guinevere A; Quartarone, Eliana; Righetti, Pierpaolo; Mustarelli, Piercarlo; Magistris, Aldo

2011-07-14

25

Preparation and physical properties of (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membrane for phosphoric acid – Fuel cells  

PubMed Central

A solid acid membranes based on poly (vinyl alcohol) (PVA), sodium bromide (NaBr) and phosphoric acid (H3PO4) were prepared by a solution casting method. The morphological, IR, electrical and optical properties of the (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membranes where x = 0.00, 0.85, 1.7, 3.4, 5.1 M were investigated. The variation of film morphology was examined by scanning electron microscopy (SEM) studies. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of phosphoric acid with host polymeric matrix. The temperature dependent nature of ionic conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The ionic conductivity at room temperature was found to be strongly depends on the H3PO4 concentration which it has been achieved to be of the order 4.3 × 10?3 S/cm at ambient temperature. Optical measurements showed a decrease in optical band gap and an increase in band tail width with the increase of phosphoric acid. The data shows that the (PVA)0.7(NaBr)0.3(H3PO4)xM solid acid membrane is promising for intermediate temperature phosphoric acid fuel cell applications. PMID:25685413

Ahmad, F.; Sheha, E.

2012-01-01

26

Preparation and physical properties of (PVA)0.7(NaBr)0.3(H3PO4) x M solid acid membrane for phosphoric acid - Fuel cells.  

PubMed

A solid acid membranes based on poly (vinyl alcohol) (PVA), sodium bromide (NaBr) and phosphoric acid (H3PO4) were prepared by a solution casting method. The morphological, IR, electrical and optical properties of the (PVA)0.7(NaBr)0.3(H3PO4) x M solid acid membranes where x = 0.00, 0.85, 1.7, 3.4, 5.1 M were investigated. The variation of film morphology was examined by scanning electron microscopy (SEM) studies. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of phosphoric acid with host polymeric matrix. The temperature dependent nature of ionic conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The ionic conductivity at room temperature was found to be strongly depends on the H3PO4 concentration which it has been achieved to be of the order 4.3 × 10(-3) S/cm at ambient temperature. Optical measurements showed a decrease in optical band gap and an increase in band tail width with the increase of phosphoric acid. The data shows that the (PVA)0.7(NaBr)0.3(H3PO4) x M solid acid membrane is promising for intermediate temperature phosphoric acid fuel cell applications. PMID:25685413

Ahmad, F; Sheha, E

2013-03-01

27

Quantification of competing H3PO4 versus HPO3 + H2O neutral losses from regioselective 18O-labeled phosphopeptides.  

PubMed

Abundant neutral losses of 98 Da are often observed upon ion trap CID-MS/MS of protonated phosphopeptide ions. Two competing fragmentation pathways are involved in this process, namely, the direct loss of H3PO4 from the phosphorylated residue and the combined losses of HPO3 and H2O from the phosphorylation site and from an additional site within the peptide, respectively. These competing pathways produce product ions with different structures but the same m/z values, potentially limiting the utility of CID-MS(3) for phosphorylation site localization. To quantify the relative contributions of these pathways and to determine the conditions under which each pathway predominates, we have examined the ion trap CID-MS/MS fragmentation of a series of regioselective (18)O-phosphate ester labeled phosphopeptides prepared using novel solution-phase amino acid synthesis and solid-phase peptide synthesis methodologies. By comparing the intensity of the -100 Da (-H3PO3 (18)O) versus -98 Da (-[HPO3 + H2O]) neutral loss product ions formed upon MS/MS, quantification of the two pathways was achieved. Factors that affect the extent of formation of the competing neutral losses were investigated, with the combined loss pathway predominantly occurring under conditions of limited proton mobility, and with increased combined losses observed for phosphothreonine compared with phosphoserine-containing peptides. The combined loss pathway was found to be less dominant under ion activation conditions associated with HCD-MS/MS. Finally, the contribution of carboxylic acid functional groups and backbone amide bonds to the water loss in the combined loss fragmentation pathway was determined via methyl esterification and by examination of a phosphopeptide lacking side-chain hydroxyl groups. PMID:24249041

Cui, Li; Yapici, Ipek; Borhan, Babak; Reid, Gavin E

2014-01-01

28

Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies  

NASA Astrophysics Data System (ADS)

Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ?G (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ?H (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

2014-02-01

29

Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.  

PubMed

FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data. PMID:24361798

Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

2014-01-30

30

Quantification of Competing H3PO4 Versus HPO3 + H2O Neutral Losses from Regioselective 18O-Labeled Phosphopeptides  

NASA Astrophysics Data System (ADS)

Abundant neutral losses of 98 Da are often observed upon ion trap CID-MS/MS of protonated phosphopeptide ions. Two competing fragmentation pathways are involved in this process, namely, the direct loss of H3PO4 from the phosphorylated residue and the combined losses of HPO3 and H2O from the phosphorylation site and from an additional site within the peptide, respectively. These competing pathways produce product ions with different structures but the same m/z values, potentially limiting the utility of CID-MS3 for phosphorylation site localization. To quantify the relative contributions of these pathways and to determine the conditions under which each pathway predominates, we have examined the ion trap CID-MS/MS fragmentation of a series of regioselective 18O-phosphate ester labeled phosphopeptides prepared using novel solution-phase amino acid synthesis and solid-phase peptide synthesis methodologies. By comparing the intensity of the -100 Da (-H3PO3 18O) versus -98 Da (-[HPO3 + H2O]) neutral loss product ions formed upon MS/MS, quantification of the two pathways was achieved. Factors that affect the extent of formation of the competing neutral losses were investigated, with the combined loss pathway predominantly occurring under conditions of limited proton mobility, and with increased combined losses observed for phosphothreonine compared with phosphoserine-containing peptides. The combined loss pathway was found to be less dominant under ion activation conditions associated with HCD-MS/MS. Finally, the contribution of carboxylic acid functional groups and backbone amide bonds to the water loss in the combined loss fragmentation pathway was determined via methyl esterification and by examination of a phosphopeptide lacking side-chain hydroxyl groups.

Cui, Li; Yapici, Ipek; Borhan, Babak; Reid, Gavin E.

2014-01-01

31

Review of HxPyOz-Catalyzed H + OH Recombination in Scramjet Nozzle Expansions; and Possible Phosphoric Acid Enhancement of Scramjet Flameholding, from Extinction of H3PO4 + H2 - Air Counterflow Diffusion Flames  

NASA Technical Reports Server (NTRS)

Recent detailed articles by Twarowski indicate that small quantities of phosphorus oxides and acids in the fuel-rich combustion products of H2 + phosphine (PH3) + air should significantly catalyze H, OH and O recombination kinetics during high-speed nozzle expansions -- to reform H2O, release heat, and approach equilibrium more rapidly and closely than uncatalyzed kinetics. This paper is an initial feasibility study to determine (a) if addition of phosphoric acid vapor (H3PO4) to a H2 fuel jet -- which is much safer than using PH3 -- will allow combustion in a high-speed scramjet engine test without adverse effects on localized flameholding, and (b) if phosphorus-containing exhaust emissions are environmentally acceptable. A well-characterized axisymmetric straight-tube opposed jet burner (OJB) tool is used to evaluate H3PO4 addition effects on the air velocity extinction limit (flame strength) of a H2 versus air counterflow diffusion flame. Addition of nitric oxide (NO), also believed to promote catalytic H-atom recombination, was evaluated for comparison. Two to five mass percent H3PO4 in the H2 jet increased flame strength 4.2%, whereas airside addition decreased it 1%. Adding 5% NO to the H2 caused a 2% decrease. Products of H-atom attack on H3PO4 produced an intense green chemiluminescence near the stagnation point. The resultant exothermic production of phosphorus oxides and acids, with accelerated H-atom recombination, released sufficient heat near the stagnation point to increase flame strength. In conclusion, the addition of H3PO4 vapor (or more reactive P sources) to hydrogen in scramjet engine tests may positively affect flameholding stability in the combustor and thrust production during supersonic expansion -- a possible dual benefit with system design / performance implications. Finally, a preliminary assessment of possible environmental effects indicates that scramjet exhaust emissions should consist of phosphoric acid aerosol, with gradual conversion to phosphate aerosol. This is compared to various natural abundances and sources.

Pellett, Gerald

2005-01-01

32

A study on electric conductivity of phosphoric acid supported on nano-pore rice husk silica in H2/Pt/H3PO4 / RHS/Pt/O2 fuel cells.  

PubMed

PEMFC (Polymer Electrolyte Membrane Fuel Cell) is widely considered as an energy conversion system from the chemical energy of hydrogen to electric energy. But, hydrogen fuel obtained from hydrocarbons has trace amount of carbon monoxide which is a potential poison for platinum electrode at the cell operating temperature approximately 100 degrees C and it becomes a huddle for the general usage of PEMFC. On the other hand PAFC (Phosphoric Acid Fuel Cell) operates at a higher temperature and the platinum electrode oxidizes carbon monoxide poison while there is a leakage problem of the liquid phase. To combine the advantages of two fuel cells, the electrolyte systems of phosphoric acid supported silica on ceramics are recently being tested. In this study, we investigated the nm pore rice husk silica as a support for phosphoric acid and tested the electric conductivity of the silica plate and the characteristics of a prototype fuel cell H2/Pt/H3PO4 / RHS/Pt/O2 at 100-200 degrees C. The conductivity of H3PO4/RHS was 8 mS cm(-1) above 175 degrees C under 200 torr H2O. In the fuel cell, the apparent conductance of the electrolyte from I-V characteristics was 2.45 mS/cm at 160 degrees C under 1 atm H2 and air at present. PMID:17252796

Hwang, Moon Jin; Lee, Soo Young; Han, Chong Soo

2006-11-01

33

Energy storage for a lunar base by the reversible chemical reaction: CaO+H2O reversible reaction Ca(OH)2  

NASA Technical Reports Server (NTRS)

A thermochemical solar energy storage concept involving the reversible reaction CaO + H2O yields Ca(OH)2 is proposed as a power system element for a lunar base. The operation and components of such a system are described. The CaO/H2O system is capable of generating electric power during both the day and night. The specific energy (energy to mass ratio) of the system was estimated to be 155 W-hr/kg. Mass of the required amount of CaO is neglected since it is obtained from lunar soil. Potential technical problems, such as reactor design and lunar soil processing, are reviewed.

Perez-Davis, Marla E.; Difilipo, Frank

1990-01-01

34

Stress-strain relationship of Ca(OH)2-activated Hwangtoh concrete.  

PubMed

This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (V agg) and the water-to-binder (W/B) ratio were selected as the main test variables. Two W/B ratios (25% and 40%) were used and the value of V agg varied between 0% and 40.0%, and 0% and 46.5% for W/B ratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in the W/B ratio and decrease in V agg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength and V agg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete. PMID:25147869

Yang, Keun-Hyeok; Mun, Ju-Hyun; Hwang, Hey-Zoo

2014-01-01

35

Stress-Strain Relationship of Ca(OH)2-Activated Hwangtoh Concrete  

PubMed Central

This study examined the stress-strain behavior of 10 calcium hydroxide (Ca(OH)2)-activated Hwangtoh concrete mixes. The volumetric ratio of the coarse aggregate (Vagg) and the water-to-binder (W/B) ratio were selected as the main test variables. Two W/B ratios (25% and 40%) were used and the value of Vagg varied between 0% and 40.0%, and 0% and 46.5% for W/B ratios of 25% and 40%, respectively. The test results demonstrated that the slope of the ascending branch of the stress-strain curve of Ca(OH)2-activated Hwangtoh concrete was smaller, and it displayed a steeper drop in stress in the descending branch, compared with those of ordinary Portland cement (OPC) concrete with the same compressive strength. This trend was more pronounced with the increase in the W/B ratio and decrease in Vagg. Based on the experimental observations, a simple and rational stress-strain model was established mathematically. Furthermore, the modulus of elasticity and strain at peak stress of the Ca(OH)2-activated Hwangtoh concrete were formulated as a function of its compressive strength and Vagg. The proposed stress-strain model predicted the actual behavior accurately, whereas the previous models formulated using OPC concrete data were limited in their applicability to Ca(OH)2-activated Hwangtoh concrete. PMID:25147869

Mun, Ju-Hyun; Hwang, Hey-Zoo

2014-01-01

36

Improvement of SO2 removal by the solubility change of Ca(OH)2 in the spray dryer system.  

PubMed

Experiments were carried out to verify the effect of the solubility change of the Ca(OH)2 sorbent on the removal of SO2 in a lab-scale spray dryer system. First, to identify the solubility effect, HNO3 was added into Ca(OH)2 slurry to increase the solubility of Ca(OH)2 by neutralization. The improvement of SO2 removal by 5-10% occurred under the condition of both 50% relative solubility and constant pH of slurry. But SO2 removal efficiency decreased steeply when the relative solubility approached 100% and the pH of the slurry decreased rapidly. For the practical application of the solubility effect, NH4Cl and NH4OH were selected as additives. Ammonium chloride (NH4Cl) which could improved Ca(OH)2 solubility removed more SO2 by 5-10% than NH4OH which showed no change in solubility. The optimal result was obtained when the slurry was fed at the ratio of 0.25mol NH4Cl/mol Ca(OH)2. The Ca(OH),/NH4Cl sorbent could remove more SO2 and improve Ca(OH)2 utilization than Ca(OH)2 sorbent in the Ca/S stoichiometric range of 1.0-1.4. It was concluded that the increase of sorbent solubility made the improvement in SO2 removal efficiency and Ca(OH)2 utilization. PMID:11816762

Song, H C; Park, J W

2001-09-01

37

New High-Pressure Phase and Pressure-Induced Amorphization of Ca(OH) 2: Grain Size Effect  

Microsoft Academic Search

In situhigh-pressure Raman spectroscopy was used to investigate the phase stability of powder and single crystal portlandite, Ca(OH)2, up to 22 GPa. Our results show that the room temperature, high-pressure behavior of this compound is strongly influenced by grain size. Compression of fine grained powder Ca(OH)2(<500 Å in thickness) leads to pressure-induced amorphization at around 11 GPa, as shown by

S. Ekbundit; K. Leinenweber; J. L. Yarger; J. S. Robinson; M. Verhelst-Voorhees; G. H. Wolf

1996-01-01

38

Dissolution and carbonation of Portlandite [Ca(OH)2] single crystals.  

PubMed

The dissolution and carbonation of portlandite (Ca(OH)2) single crystals was studied by a combination of in situ Atomic Force Microscopy, Scanning Electron Microscopy, and two-dimensional X-ray diffraction. The dissolution of portlandite {0001} surfaces in water proceeds by the formation and expansion of pseudohexagonal etch pits, with edges parallel to ?100? directions. Etch pits on {010} surfaces are elongated along ?001?, with edges parallel to ?101?. The interaction between carbonate-bearing solutions and portlandite results in the dissolution of the substrate coupled with the precipitation of thick islands of CaCO3 that appear oriented on the portlandite substrate. Ex situ carbonation of portlandite in contact with air results in the formation of pseudomorphs that fully preserve the external shape of the original portlandite single crystals. Our observations suggest that portlandite carbonation in contact with air and carbonate-bearing solutions occurs by a similar mechanism, i.e. coupled dissolution-precipitation. Calcite grows epitaxially on {0001} portlandite surfaces with the following orientation: ?001?Cc? ?001?Port. Apparently, no porosity is generated during the reaction, which progresses through the formation of fractures. Our results are of relevance to many processes in which the carbonation of portlandite takes place, such as CO2 capture and storage or the carbonation of cementitious materials. PMID:23915181

Ruiz-Agudo, Encarnación; Kud?acz, Krzysztof; Putnis, Christine V; Putnis, Andrew; Rodriguez-Navarro, Carlos

2013-10-01

39

Commercial Ca(OH)2 nanoparticles for the consolidation of immovable works of art  

NASA Astrophysics Data System (ADS)

Calcium hydroxide nanoparticles are effective components for the consolidation treatment of immovable works of art, such as carbonate stone and wall paintings that exhibit both surface and structural degradation. Several formulations have been recently developed, with different characteristics (dispersing solvent, particle size distribution and particle structure), which are expected to result in different long-term consolidating properties. In this contribution, the carbonation of a commercial Ca(OH)2 nanoparticle formulation (Nanorestore®) was characterized through Fourier transform infrared (FTIR) analysis. Nanoparticle films were laid on KBr pellets and stored at room temperature under controlled relative humidity and CO2 pressure. FTIR analysis was used to quantitatively detect the formation of calcium carbonate. Fitting of the experimental data allowed the description of the mechanism of carbonate nucleation and growth. The compatibility of the Nanorestore® formulation for wall painting consolidation was assessed through optical and electron microscopy, colorimetry and water absorption capillarity measurements. The formulation's effectiveness in consolidating powdering painted layers was assessed through application on site and on detached samples of Mesoamerican wall paintings belonging to the pre-Columbian archaeological sites of Ixcaquixtla and Calakmul (Mexico).

Baglioni, P.; Chelazzi, D.; Giorgi, R.; Carretti, E.; Toccafondi, N.; Jaidar, Y.

2014-03-01

40

Hydrolysis, acidification and dewaterability of waste activated sludge under alkaline conditions: combined effects of NaOH and Ca(OH)2.  

PubMed

Hydrolysis, acidification and dewaterability of waste activated sludge (WAS) were investigated at pH 10 controlled by the addition of NaOH, Ca(OH)2 or their mixtures at various ratios. Similar efficiency of WAS solublisation was observed in all cases, at 38-40%. High volatile fatty acid (VFA) production and good sludge dewaterability could not be achieved simultaneously by adding NaOH or Ca(OH)2 alone, but could be achieved by adding mixtures of NaOH and Ca(OH)2. VFA production in the case with the addition of Ca(OH)2 only (1201 mg(COD)/L) was lower than in the cases with the addition of NaOH or its mixtures with Ca(OH)2 (1813-1868 mg(COD)/L), and the lower VFA production with Ca(OH)2 addition alone could be related to the fact that a higher concentration of Ca(2+) was released into the fermentation liquid, which likely inhibited the hydrolysis process of protein. Furthermore, adding mixtures of NaOH and Ca(OH)2 was more economical for VFA production. PMID:23567686

Su, Gaoqiang; Huo, Mingxin; Yuan, Zhiguo; Wang, Shuying; Peng, Yongzhen

2013-05-01

41

Gas-solid carbonation of Ca(OH)2 and CaO particles under non-isothermal and isothermal conditions by using a thermogravimetric analyzer  

E-print Network

1 Gas-solid carbonation of Ca(OH)2 and CaO particles under non-isothermal and isothermal conditions Gas Control 11, 3 (2012) 172-180" DOI : 10.1016/j.ijggc.2012.08.009 #12;2 Abstract The gas-solid, quantify the gas-solid carbonation extent and the carbonation kinetics of Ca(OH)2 and CaO; and secondly

Boyer, Edmond

42

A note on the comparison of crack resistance of Ca(OH) 2 crystals of unmodified and polymer-modified mortars in carbonated atmosphere  

Microsoft Academic Search

The purpose of this paper is to study morphologically the effects of carbonation on Ca(OH)2 crystals in unmodified mortar and polymer-modified mortars (PMMs). For this purpose, unmodified mortar and PMMs with 25 mix proportions were prepared with various polymer–cement ratios (P\\/C) and subjected to a nonpressurizing accelerated carbonation test (NPACT). It was concluded that Ca(OH)2 crystals formed in unmodified mortar

M. U. K. Afridi; Y. Ohama; K. Demura; M. Z. Iqbal

2001-01-01

43

Short-term effects of Ca(OH) 2 additions on phytoplankton biomass: A comparison of laboratory and in situ experiments  

Microsoft Academic Search

To identify mechanisms by which Ca(OH)2 additions reduce phytoplankton biomass in the short term (<20 d), we investigated changes in concentrations of chlorophyll a (chl a), total phosphorus (TP) and calcium (Ca), and pH and turbidity in four eutrophic hardwater lakes, two dugouts and limnocorrals. We also tested the potential effects of high pH and turbidity on biomass of three

Y. Zhang; E. E. Prepas

1996-01-01

44

Bacterial Efficacy of Ca(oH)2 Against E.faecalis Compared with three Dental Lasers on Root Canal Dentin- An Invitro Study  

PubMed Central

Aim: The aim of this study was to evaluate bactericidal effect of Ca(OH)2 compared with 810 nm diode, 980 nm diode, and Nd:YAG lasers on root canal dentin against E.faecalis. Materials and Methods: Sixty five freshly extracted human mandibular single rooted teeth were selected for the study. The apical third of these roots was gradually enlarged until reaching the ISO 40- K file. The samples were divided into 4 groups, each containing 15 teeth and 5 teeth for control group. Group-1: 810 nm Diode; Group-2: 980 nm Diode; Group-3: Nd:YAG; Group-4: Ca(OH)2. 50?L of the E.faecalis ATCC 29212 strand was incubated in 1 mL of Brain Heart Infusion Broth (BHI) culture medium in37oC incubator for 4h. The concentration of the inoculation was then adjusted for a degree of turbidity which was adjusted to 0.5 McFarland scale. Later from the incubated broth, 10?L of E.faecalis culture was inoculated into the main canal and were sealed. Results: The incubated plates were checked for growth and the colony was counted using colony counter and the results are interpreted. There was statistically significant difference (p<0.05) amongst the Ca(OH)2 group regarding the laser groups. Conclusion: The teeth irradiated with the Nd:YAG laser had significantly higher bacterial reduction than all the other groups and the respective control groups. PMID:25584306

Subbaiah, Rama

2014-01-01

45

Improved polybenzimidazole films for H 3PO 4-doped PBI-based high temperature PEMFC  

Microsoft Academic Search

In this work, the influence of several parameters that seem to affect the polycondensation synthesis of PBI has been studied. A significant effect of the dosage of polyphosphoric acid on the resulting molecular weight of PBI was observed. Conversely, the addition of drying agent (P2O5) or catalyst (triphenyl phosphate) appeared not to be beneficial. Likewise, temperature increased strongly the molecular

J. Lobato; P. Cañizares; M. A. Rodrigo; J. J. Linares; J. A. Aguilar

2007-01-01

46

Numerical Modeling of In-situ Reaction Barrier by Injection of Ca(OH)2 Solution for CO2 Geological Storage  

NASA Astrophysics Data System (ADS)

Containment of CO2 in the storage reservoir is a very important issue. We present here an in-situ reaction barrier method to reduce the medium permeability along potential leakage paths of a deep CO2 storage reservoir in a saline formation. An aqueous solution will be injected into the fractures and rocks through injection wells. The solution will have a low viscosity and will not impact formation permeability as long as the solution is left as it is, but when the solution encounters dissolved CO2, precipitation will occur due to chemical reaction. As a result, the permeability will be reduced by filling the pores and fractures in the rocks with the precipitates. This concept has been successfully demonstrated previously through a laboratory experiment using Ca(OH)2 solution. The reduction of permeability in the laboratory experiment has been reproduced by reactive transport modeling using TOUGHREACT. The concept of the in-situ reaction barrier has been applied to a 2-D caprock-aquifer system under field physical and chemical conditions using the modeling tool. Calcite precipitation, permeability reduction, and CO2 leakage mitigation was achieved in the numerical experiment. This concept may be also applicable to prevent the leakage through abandoned wells, to mitigate well cement degradation, and to enhance CO2 mineral trapping.

Xu, T.; Ito, T.

2008-12-01

47

Grain-boundary migration in KCl bicrystals  

NASA Technical Reports Server (NTRS)

Boundary migration in melt-grown bicrystals of KCl containing pure twist boundaries was investigated. The experiments involve the use of bicrystal specimens in the shape of right-triangular prisms with the boundary parallel to one side.

Gibbon, C. F.

1968-01-01

48

In-vitro apatite formation on phosphorylated bamboo.  

PubMed

Natural self-reinforced composite, bamboo, was surface modified by phosphorylation with urea-H3PO4 and NaOH-H3PO4 methods; then precalcification was performed by immersing samples in saturated Ca(OH)2 solution. After that, calcium phosphate can be formed on the surface of bamboo samples in calcification media: simulated body fluid (1.5 SBF) and accelerated calcification solution (ACS). Experimental results reveal that pre-calcification is an inevitable step for the formation of calcium phosphate. The calcium phosphate formed in 1.5 SBF was identified by thin-film X-ray diffraction as apatite which was not well crystallized. Compared with the urea-H3PO4 method, the NaOH-H3PO4 method has the advantages of quicker and continuous apatite formation and stronger adhesive between apatite and bamboo. PMID:15348706

Li, S; Liu, Q; de Wijn, J; Wolke, J; Zhou, B; de Groot, K

1997-09-01

49

Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.  

PubMed

The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. PMID:25721981

Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

2015-05-01

50

Stress-Strain Curves and Slip Bands of KCl Whiskers  

Microsoft Academic Search

Tensile tests were made, at room temperature, on KCl whiskers grown on outer surfaces of thin cellophane bags containing saturated aqueous solution. It was found that their stress-strain curves consist of four deformation stages. Slip bands were straight in the early stage of deformation, but rumpled surfaces were observed in the later stages under an optical microscope. Deformed specimen showed

Kazuhiko Yoshida

1965-01-01

51

Photoelectric Hall Effect in KCl at Low Temperatures  

Microsoft Academic Search

The Hall effect for carriers released by light has been studied over a temperature range 4° to 114°K in additively colored crystals of KCl containing various concentrations of F centers. A negative Hall signal was observed corresponding to electrons released from F centers by light absorbed in the high-energy side of the F band. The Hall mobility rises steeply below

Frederick C. Brown; Nicolas Inchauspe

1961-01-01

52

Molecular dynamics simulations of the melting of KCl nanoparticles  

NASA Astrophysics Data System (ADS)

Molecular dynamics (MD) simulations are used to investigate the thermodynamic properties and structural changes of KCl spherical nanoparticles at various sizes (1064, 1736, 2800, 3648, 4224 and 5832 ions) upon heating. The melting temperature is dependent on both the size and shape of KCl models, and the behaviour of the first order phase transition is also found in the present work. The surface melting found here is different from the melting phenomena of KCl models or other alkali halides studied in the past. In the premelting stage, a mixed phase containing liquid and solid ions covers the surface of nanoparticles. The only peak of heat capacity spreads out a significant segment of temperature, probably exhibiting both heterogeneous melting on the surface and homogeneous melting in the core. The coexistence of two melting mechanisms, homogeneous and heterogeneous ones, in our model is unlike those considered previously. We also found that the critical Lindemann ratio of the KCl nanoparticle becomes much more stable when the size of the nanoparticle is of the order of thousands of ions. A picture of the structural evolution upon heating is studied in more detail via the radial distribution function (RDF) and coordination numbers. Our results are in a good agreement with previous MD simulations and experimental observations.

Sang, Le Van; Huong, Ta Thi Thuy; Minh, Le Nguyen Tue

2014-10-01

53

Studies of self-trapped exciton luminescence in KCl  

Microsoft Academic Search

Measurements have been made of the luminescence intensity, lifetime, emission spectra, and linear polarization of self-trapped exciton luminescence in KCl (2.31 eV) at temperatures of 7oK and above. Data are interpreted in terms of an exciton energy-level structure composed of a singlet state approximately 15 meV above a triplet state. The singlet state is populated only by thermal excitation from

A. E. Purdy; R. B. Murray; K. S. Song; A. M. Stoneham

1977-01-01

54

Theoretical and empirical investigations of KCl:Eu2+ for nearly water-equivalent radiotherapy dosimetry  

PubMed Central

Purpose: The low effective atomic number, reusability, and other computed radiography-related advantages make europium doped potassium chloride (KCl:Eu2+) a promising dosimetry material. The purpose of this study is to model KCl:Eu2+ point dosimeters with a Monte Carlo (MC) method and, using this model, to investigate the dose responses of two-dimensional (2D) KCl:Eu2+ storage phosphor films (SPFs). Methods: KCl:Eu2+ point dosimeters were irradiated using a 6 MV beam at four depths (5–20 cm) for each of five square field sizes (5×5–25×25 cm2). The dose measured by KCl:Eu2+ was compared to that measured by an ionization chamber to obtain the magnitude of energy dependent dose measurement artifact. The measurements were simulated using DOSXYZnrc with phase space files generated by BEAMnrcMP. Simulations were also performed for KCl:Eu2+ films with thicknesses ranging from 1 ?m to 1 mm. The work function of the prototype KCl:Eu2+ material was determined by comparing the sensitivity of a 150 ?m thick KCl:Eu2+ film to a commercial BaFBr0.85I0.15:Eu2+-based SPF with a known work function. The work function was then used to estimate the sensitivity of a 1 ?m thick KCl:Eu2+ film. Results: The simulated dose responses of prototype KCl:Eu2+ point dosimeters agree well with measurement data acquired by irradiating the dosimeters in the 6 MV beam with varying field size and depth. Furthermore, simulations with films demonstrate that an ultrathin KCl:Eu2+ film with thickness of the order of 1 ?m would have nearly water-equivalent dose response. The simulation results can be understood using classic cavity theories. Finally, preliminary experiments and theoretical calculations show that ultrathin KCl:Eu2+ film could provide excellent signal in a 1 cGy dose-to-water irradiation. Conclusions: In conclusion, the authors demonstrate that KCl:Eu2+-based dosimeters can be accurately modeled by a MC method and that 2D KCl:Eu2+ films of the order of 1 ?m thick would have minimal energy dependence. The data support the future research and development of a KCl:Eu2+ storage phosphor-based system for quantitative, high-resolution multidimensional radiation therapy dosimetry. PMID:20175476

Zheng, Yuanshui; Han, Zhaohui; Driewer, Joseph P.; Low, Daniel A.; Li, H. Harold

2010-01-01

55

Thiol-dependent passive K:Cl transport in sheep red blood cells: X. A hydroxylamine-oxidation induced K:Cl flux blocked by diethylpyrocarbonate  

Microsoft Academic Search

Summary Hydroxylamine, a potent oxidizing agent used to reverse carbethoxylation of histidine by diethylpyrocarbonate, activated Cl-dependent K flux (K:Cl cotransport) of low K sheep red blood cells almost sixfold. When K:Cl cotransport was already stimulated by N-ethylmaleimide, hydroxylamine caused an additional twofold activation suggesting modification of sites different from those thiol alkylated. This conclusion was supported by the finding that

P. K. Lauf

1990-01-01

56

Morphological and Structural Investigation of Sexithiophene Growth on KCl (100).  

PubMed

The morphology and structure of sexithiophene deposited on KCl (100) substrates was investigated by scanning force microscopy and specular X-ray diffraction measurements. Two different needle-like structures with {010} and {4?11} contact planes have been observed as well as islands of almost upright standing sexithiophene molecules with a {100} contact plane. Furthermore an azimuthal alignment of all three crystal orientations was observed by X-ray diffraction pole figure measurements, and the growth directions reflect the 4-fold rotational symmetry of the substrate surface. In addition the analysis of crystals with {4?11} and {100} contact planes unveiled that they share a common crystallographic direction which is explained by ledge directed epitaxy. PMID:23413362

Schwabegger, Günther; Djuric, Tatjana; Sitter, Helmut; Resel, Roland; Simbrunner, Clemens

2013-02-01

57

Concentration and precipitation of NaCl and KCl from salt cake leach solutions by electrodialysis  

SciTech Connect

Electrodialysis was investigated for cost-effective recovery of salt from salt cake leach solutions. (Salt cake is a waste stream generated by the aluminum industry during treatment of aluminum drosses and scrap.) We used a pilot-scale electrodialysis stack of 5 membrane pairs, each with an effective area of 0.02 m{sup 2}. The diluate stream contained synthetic NaCl, KCl,mixtures of NaCl and KCl, and actual salt cake leach solutions (mainly NaCl and KCl, with small amounts of MgCl{sub 2}). We concentrated and precipitated NaCl and KCl salts from the concentrate steam when the initial diluate stream concentration was 21.5 to 28.8 wt% NaCl and KCl. We found that water transferring through the membranes was a significant factor in overall efficiency of salt recovery by electrodialysis.

Sreenivasarao, K; Patsiogiannis, F.; Hryn, J.N.

1997-02-09

58

Radiation effects on beta /10.6/ of pure and europium doped KCl  

NASA Technical Reports Server (NTRS)

Changes in the optical absorption coefficient as the result of X-ray and electron bombardment of pure monocrystalline and polycrystalline KCl and of divalent europium doped polycrystalline KCl were determined. A constant heat flow calorimetric method was used to measure the optical absorption coefficients. Both 300 kV X-ray irradiation and 2 MeV electron irradiation produced increases in the optical absorption coefficient at room temperature. X-ray irradiation produced more significant changes in pure monocrystalline KCl than equivalent amounts of electron irradiation. Electron irradiation of pure and Eu-doped polycrystalline KCl produced increases in the absorption by as much as a factor of 20 over untreated material. Bleaching of the electron-irradiated doped KCl with 649 millimicron light produced a further increase.

Grimes, H. H.; Maisel, J. E.; Hartford, R. H.

1975-01-01

59

Polarized emission from KCl:Eu2+ single crystals  

NASA Astrophysics Data System (ADS)

The polarization emission spectrum and the angular dependence of polarization ratio of the blue emission from KCl:Eu2+ were investigated at 78.8 K. The polarized emission at 420 nm consisted of several components. The angular dependence of polarization ratio of each component is proportional to sin(2icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> ) or -cos(2icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> ), when the exciting light is polarized at icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> with respect to the z -axis for the [100]-[010] optical arrangement. The relaxed excited states (RESs) of Eu2+ responsible for the 420 nm emission are presented in terms of the adiabatic potential energy surface (APES), taking into account the Jahn-Teller effect (JTE) coupling to the Eg mode and the spin-orbit (SO) interaction. The charge-compensating cation vacancy (CCV, Vc - ) also causes an additive perturbation.

Kang, Jun-Gill; Sohn, Youngku; Nah, Min-Kook; Kim, Youn-Doo; Ogryzlo, Elmer A.

2000-04-01

60

KCl Mediates K+ Channel-Activated Mitogen-Activated Protein Kinases Signaling in Wound Healing  

PubMed Central

Background Wound healing is an interaction of a complex signaling cascade of cellular events, including inflammation, proliferation, and maturation. K+ channels modulate the mitogen-activated protein kinase (MAPK) signaling pathway. Here, we investigated whether K+ channel-activated MAPK signaling directs collagen synthesis and angiogenesis in wound healing. Methods The human skin fibroblast HS27 cell line was used to examine cell viability and collagen synthesis after potassium chloride (KCl) treatment by Cell Counting Kit-8 (CCK-8) and western blotting. To investigate whether K+ ion channels function upstream of MAPK signaling, thus affecting collagen synthesis and angiogenesis, we examined alteration of MAPK expression after treatment with KCl (channel inhibitor), NS1619 (channel activator), or kinase inhibitors. To research the effect of KCl on angiogenesis, angiogenesis-related proteins such as thrombospondin 1 (TSP1), anti-angiogenic factor, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), pro-angiogenic factor were assayed by western blot. Results The viability of HS27 cells was not affected by 25 mM KCl. Collagen synthesis increased dependent on time and concentration of KCl exposure. The phosphorylations of MAPK proteins such as extracellular-signal-regulated kinase (ERK) and p38 increased about 2.5-3 fold in the KCl treatment cells and were inhibited by treatment of NS1619. TSP1 expression increased by 100%, bFGF expression decreased by 40%, and there is no significant differences in the VEGF level by KCl treatment, TSP1 was inhibited by NS1619 or kinase inhibitors. Conclusions Our results suggest that KCl may function as a therapeutic agent for wound healing in the skin through MAPK signaling mediated by the K+ ion channel. PMID:25606484

Shim, Jung Hee; Lim, Jong Woo; Kim, Byeong Kyu; Park, Soo Jin; Kim, Suk Wha

2015-01-01

61

Concentration and precipitation of NaCl and KCl from salt cake leach solutions by electrodialysis  

Microsoft Academic Search

Electrodialysis was investigated for cost-effective recovery of salt from salt cake leach solutions. (Salt cake is a waste stream generated by the aluminum industry during treatment of aluminum drosses and scrap.) We used a pilot-scale electrodialysis stack of 5 membrane pairs, each with an effective area of 0.02 m². The diluate stream contained synthetic NaCl, KCl,mixtures of NaCl and KCl,

K Sreenivasarao; F. Patsiogiannis; J. N. Hryn

1997-01-01

62

A simplified model of TiH1.65\\/KClO4 pyrotechnic ignition  

Microsoft Academic Search

A simplified model was developed and is presented in this report for simulating thermal transport coupled with chemical reactions that lead to the pyrotechnic ignition of TiH1.65\\/KClO4 powder. The model takes into account Joule heating via a bridgewire, thermal contact resistance at the wire\\/powder interface, convective heat loss to the surroundings, and heat released from the TiH1.65- and KClO4-decomposition and

Ken Shuang

2009-01-01

63

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

USGS Publications Warehouse

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.

Potter, R.W., II; Clynne, M.A.

1980-01-01

64

Radiation effects on beta 10.6 of pure and europium doped KCl  

NASA Technical Reports Server (NTRS)

Changes in the optical absorption coefficient as a result of X-ray and electron bombardment of pure KCl (monocrystalline and polycrystalline), and divalent europium doped polycrystalline KCl were determined. The optical absorption coefficients were measured by a constant heat flow calorimetric method. Both 300 KV X-irradiation and 2 MeV electron irradiation produced significant increases in beta 10.6, measured at room temperature. The X-irradiation of pure moncrystalline KCl increased beta 10.6 by 0.005/cm for a 113 MR dose. For an equivalent dose, 2 MeV electrons were found less efficient in changing beta 10.6. However, electron irradiation of pure and Eu-doped polycrystalline KCl produced marked increases in adsorption. Beta increased to over 0.25/cm in Eu-doped material for a 30 x 10 to the 14th power electrons/sq cm dose, a factor of 20 increase over unirradiated material. Moreover, bleaching the electron irradiated doped KCl with 649 m light produced and additional factor of 1.5 increase. These findings will be discussed in light of known defect-center properties in KCl.

Grimes, H. H.; Maisel, J. E.; Hartford, R. H.

1975-01-01

65

Influence of partial replacement of NaCl with KCl on profiles of volatile compounds in dry-cured bacon during processing  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study investigated the influence of partial substitution of NaCl with KCl on the formation of volatile compounds in bacons during processing using a purge and trap dynamic headspace GC/MS system. Three substitutions were 0% KCl (I), 40% KCl (II), and 70% KCl (III). The profiles of the volatile ...

66

Calculation of the standard partial molal thermodynamic properties of KCl{sup 0} and activity coefficients of aqueous KCl at temperatures and pressures to 1000{degree}C and 5 kbar  

SciTech Connect

Regression of experimental activity coefficient and dissociation constant data reported in the literature with the Hueckel and Setchenow equations and the revised HKF equations of state generated parameters and thermodynamic properties of dissociated KCl and KCl{sup 0} at 25{degrees}C and bar that can be used to calculate the standard partial molal thermodynamic properties of KCl{sup 0} and the activity coefficients of KCl at temperatures and pressures to 1000{degrees}C and 5 kbar. 46 refs., 6 figs., 4 tabs.

Pokrovskii, V.A. [ETH Zentrum, Zuerich (Switzerland)] [ETH Zentrum, Zuerich (Switzerland); Helgeson, H.C. [Univ. of California, Berkeley, CA (United States)] [Univ. of California, Berkeley, CA (United States)

1997-06-01

67

KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7 × 7.  

PubMed

The growth of ultra-thin KCl films on the Si(111)7 × 7 reconstructed surface has been investigated as a function of KCl coverage and substrate temperature. The structure and morphology of the films were characterized by means of scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. Detailed analysis of the atomically resolved STM images of islands grown at room and high temperatures (400?K-430?K) revealed the presence of KCl(001) and KCl(111) islands with the ratio between both structures depending on the growth temperature. At room temperature, the growth of the first layer, which covers the initial Si(111)7 × 7 surface, contains double/triple atomic layers of KCl(001) with a small fraction of KCl(111) islands. The high temperature growth promotes the appearance of large KCl(111) areas, which are built up by three atomic layers. At room and high temperatures, flat and atomically well-defined ultra-thin KCl films can be grown on the Si(111)7 × 7 substrate. The formation of the above mentioned (111) polar films is interpreted as a result of the thermally activated dissociative adsorption of KCl molecules on Si(111)7 × 7, which produces an excess of potassium on the Si surface. PMID:25650038

Beinik, Igor; Barth, Clemens; Hanbücken, Margrit; Masson, Laurence

2015-01-01

68

KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7 × 7  

NASA Astrophysics Data System (ADS)

The growth of ultra-thin KCl films on the Si(111)7 × 7 reconstructed surface has been investigated as a function of KCl coverage and substrate temperature. The structure and morphology of the films were characterized by means of scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. Detailed analysis of the atomically resolved STM images of islands grown at room and high temperatures (400 K-430 K) revealed the presence of KCl(001) and KCl(111) islands with the ratio between both structures depending on the growth temperature. At room temperature, the growth of the first layer, which covers the initial Si(111)7 × 7 surface, contains double/triple atomic layers of KCl(001) with a small fraction of KCl(111) islands. The high temperature growth promotes the appearance of large KCl(111) areas, which are built up by three atomic layers. At room and high temperatures, flat and atomically well-defined ultra-thin KCl films can be grown on the Si(111)7 × 7 substrate. The formation of the above mentioned (111) polar films is interpreted as a result of the thermally activated dissociative adsorption of KCl molecules on Si(111)7 × 7, which produces an excess of potassium on the Si surface.

Beinik, Igor; Barth, Clemens; Hanbücken, Margrit; Masson, Laurence

2015-02-01

69

KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7 × 7  

PubMed Central

The growth of ultra-thin KCl films on the Si(111)7 × 7 reconstructed surface has been investigated as a function of KCl coverage and substrate temperature. The structure and morphology of the films were characterized by means of scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. Detailed analysis of the atomically resolved STM images of islands grown at room and high temperatures (400?K–430?K) revealed the presence of KCl(001) and KCl(111) islands with the ratio between both structures depending on the growth temperature. At room temperature, the growth of the first layer, which covers the initial Si(111)7 × 7 surface, contains double/triple atomic layers of KCl(001) with a small fraction of KCl(111) islands. The high temperature growth promotes the appearance of large KCl(111) areas, which are built up by three atomic layers. At room and high temperatures, flat and atomically well-defined ultra-thin KCl films can be grown on the Si(111)7 × 7 substrate. The formation of the above mentioned (111) polar films is interpreted as a result of the thermally activated dissociative adsorption of KCl molecules on Si(111)7 × 7, which produces an excess of potassium on the Si surface. PMID:25650038

Beinik, Igor; Barth, Clemens; Hanbücken, Margrit; Masson, Laurence

2015-01-01

70

Off-center position of the Li+ ion in the FA center in KCl  

NASA Astrophysics Data System (ADS)

The photostimulated reorientation of FA centers in KCl: Li+ is affected by the off-axis geometry of the dipoles and by the overlap between the FA1 and FA2 absorption bands at each pumping wavelength. A detailed model of such a process, so far successfully compared to experimental results of optical absorption and emission in stationary equilibrium conditions, has been applied to studies of transient effects. The results further confirm the value of the off-axis angle of FA (Li) centers in KCl.

Baldacchini, G.; Grassano, U. M.; Scacco, A.; Somma, F.

1988-03-01

71

Whisker growth by means of cellulose acetate membranes: NaCl and KCl  

NASA Astrophysics Data System (ADS)

NaCl and KCl whiskers were successfully grown from non-concentrated solutions by means of cellulose acetate (CA) membranes. Substantial growth was obtained within several hours on the part of the membrane not submerged in the solution. It is possible to do this with the mother liquor concentration barely affected by the whisker growth. The growth rate is controlled by water evaporation from the membrane. The driving force of the process in the case of NaCl and KCl solutions is the evaporation of water and the membrane affinity for it.

Yellin, N.; Zelingher, N.; Ben-Dor, L.

1985-04-01

72

Thermodynamics of neptunium in LiCl-KCl eutectic\\/liquid bismuth systems  

Microsoft Academic Search

Thermodynamic properties of neptunium in LiCl-KCl eutectic\\/liquid bismuth systems in the temperature range 400--500 C have been studied using a galvanic cell method for the pyrometallurgical reprocessing of nuclear spent fuels. The standard potential of the Np\\/Np(III) couple vs. the Ag\\/AgCl (1 wt% AgCl) reference electrode in LiCl-KCl eutectic was measured and given by the equation E{sub Np\\/Np(III)}° = -2.0667

Y. Sakamura; O. Shirai; T. Iwai; Y. Suzuki

2000-01-01

73

Life at high salt concentrations, intracellular KCl concentrations, and acidic proteomes  

PubMed Central

Extremely halophilic microorganisms that accumulate KCl for osmotic balance (the Halobacteriaceae, Salinibacter) have a large excess of acidic amino acids in their proteins. This minireview explores the occurrence of acidic proteomes in halophiles of different physiology and phylogenetic affiliation. For fermentative bacteria of the order Halanaerobiales, known to accumulate KCl, an acidic proteome was predicted. However, this is not confirmed by genome analysis. The reported excess of acidic amino acids is due to a high content of Gln and Asn, which yield Glu and Asp upon acid hydrolysis. The closely related Halorhodospira halophila and Halorhodospira halochloris use different strategies to cope with high salt. The first has an acidic proteome and accumulates high KCl concentrations at high salt concentrations; the second does not accumulate KCl and lacks an acidic proteome. Acidic proteomes can be predicted from the genomes of some moderately halophilic aerobes that accumulate organic osmotic solutes (Halomonas elongata, Chromohalobacter salexigens) and some marine bacteria. Based on the information on cultured species it is possible to understand the pI profiles predicted from metagenomic data from hypersaline environments. PMID:24204364

Oren, Aharon

2013-01-01

74

Life at high salt concentrations, intracellular KCl concentrations, and acidic proteomes.  

PubMed

Extremely halophilic microorganisms that accumulate KCl for osmotic balance (the Halobacteriaceae, Salinibacter) have a large excess of acidic amino acids in their proteins. This minireview explores the occurrence of acidic proteomes in halophiles of different physiology and phylogenetic affiliation. For fermentative bacteria of the order Halanaerobiales, known to accumulate KCl, an acidic proteome was predicted. However, this is not confirmed by genome analysis. The reported excess of acidic amino acids is due to a high content of Gln and Asn, which yield Glu and Asp upon acid hydrolysis. The closely related Halorhodospira halophila and Halorhodospira halochloris use different strategies to cope with high salt. The first has an acidic proteome and accumulates high KCl concentrations at high salt concentrations; the second does not accumulate KCl and lacks an acidic proteome. Acidic proteomes can be predicted from the genomes of some moderately halophilic aerobes that accumulate organic osmotic solutes (Halomonas elongata, Chromohalobacter salexigens) and some marine bacteria. Based on the information on cultured species it is possible to understand the pI profiles predicted from metagenomic data from hypersaline environments. PMID:24204364

Oren, Aharon

2013-01-01

75

Quantitative megavoltage radiation therapy dosimetry using the storage phosphor KCl:Eu2+  

PubMed Central

This work, for the first time, reports the use of europium doped potassium chloride (KCl:Eu2+) storage phosphor for quantitative megavoltage radiation therapy dosimetry. In principle, KCl:Eu2+ functions using the same photostimulatated luminescence (PSL) mechanism as commercially available BaFBr0.85I0.15:Eu2+ material that is used for computed radiography (CR) but features a significantly smaller effective atomic number—18 versus 49—making it a potentially useful material for nearly tissue-equivalent radiation dosimetry. Cylindrical KCl:Eu2+ dosimeters, 7 mm in diameter and 1 mm thick, were fabricated in-house. Dosimetric properties, including radiation hardness, response linearity, signal fading, dose rate sensitivity, and energy dependence, were studied with a laboratory optical reader after irradiation by a linear accelerator. The overall experimental uncertainty was estimated to be within ±2.5%. The findings were (1) KCl:Eu2+ showed satisfactory radiation hardness. There was no significant change in the stimulation spectra after irradiation up to 200 Gy when compared to a fresh dosimeter, indicating that this material could be reused at least 100 times if 2 Gy per use was assumed, e.g., for patient-specific IMRT QA. (2) KCl:Eu2+ exhibited supralinear response to dose after irradiation from 0 to 800 cGy. (3) After x ray irradiation, the PSL signal faded with time and eventually reached a fading rate of about 0.1%?h after 12 h. (4) The sensitivity of the dosimeter was independent of the dose rate ranging from 15 to 1000 cGy?min. (5) The sensitivity showed no beam energy dependence for either open x ray or megavoltage electron fields. (6) Over-response to low-energy scattered photons was comparable to radiographic film, e.g., Kodak EDR2 film. By sandwiching dosimeters between low-energy photon filters (0.3 mm thick lead foils) during irradiation, the over-response was reduced. The authors have demonstrated that KCl:Eu2+ dosimeters have many desirable dosimetric characteristics that make the material conducive to radiation therapy dosimetry. In the future, a large-area KCl:Eu2+-based CR plate with a thickness of the order of a few microns, created using modern thin film techniques, could provide a reusable, quantitative, high-resolution two-dimensional dosimeter with minimal energy dependence. PMID:19746808

Han, Zhaohui; Driewer, Joseph P.; Zheng, Yuanshui; Low, Daniel A.; Li, H. Harold

2009-01-01

76

KCl depolarization increases Ca2+ sensitivity of contractile elements in coronary arterial smooth muscle.  

PubMed

The effects of KCl depolarization on the Ca2+ sensitivity of contractile elements were studied using simultaneous measurement of intracellular Ca2+ concentration ([Ca2+]i) and force of contraction in isolated canine coronary artery. Perfusion with 90 mM KCl-2.5 mM CaCl2 physiological salt solution (PSS) (90K-2.5Ca) increased [Ca2+]i and elicited a contraction. The repolarization produced by 5 mM KCl-2.5 mM CaCl2 PSS (5K-2.5Ca) or the removal of extracellular Ca2+ ([Ca2+]o) and addition of 1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA; 90K-0Ca) induced decreases in [Ca2+]i and relaxations. The relaxation induced by 90K-0Ca was slower than that induced by 5K-2.5Ca without significant difference in the decrease in [Ca2+]i, suggesting that the Ca2+ sensitivity may be increased in depolarized muscles in 90K-0Ca. The reduction of extracellular Na+ concentration did not slow down the relaxation. The [Ca2+]i-force relation curve in 30K-0Ca was between that in 5K-0Ca and that in 90K-0Ca. The [Ca2+]i-force relationship curve obtained by changing the extracellular K+ concentration stepwise in 2.5 mM CaCl2 PSS was located to the right of that by changing [Ca2+]o in 90 mM KCl PSS. These results indicate that KCl depolarization increases the Ca2+ sensitivity of contractile elements. There may be a signal transduction system for the sarcolemma to regulate Ca2+ sensitivity of contractile elements by the level of membrane potential. PMID:8067417

Yanagisawa, T; Okada, Y

1994-08-01

77

Performance of KCl:Eu2+ storage phosphor dosimeters for low-dose measurements  

NASA Astrophysics Data System (ADS)

Recent research has demonstrated that europium doped potassium chloride (KCl:Eu2+) storage phosphor material has the potential to become the physical foundation of a novel and reusable dosimetry system using either film-like devices or devices similar to thermoluminescent dosimeter chips. The purposes of this work are to quantify the performance of KCl:Eu2+ prototype dosimeters for low-dose measurements and to demonstrate how it can be incorporated into clinical application for in vivo peripheral dose measurements. Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The dosimeters were read using a laboratory photostimulated luminescence detection system. KCl:Eu2+ prototype storage phosphor dosimeter was capable of measuring a dose-to-water as low as 0.01 cGy from a 6 MV photon beam with a signal-to-noise ratio greater than 6. A pre-readout thermal annealing procedure enabled the dosimeter to be read within an hour post-irradiation. After receiving large accumulated doses (˜10 kGy), the dosimeters retained linear response in the low-dose region with only a 20% loss of sensitivity comparing to a fresh sample (zero Gy history). The energy dependence encountered during low-dose peripheral measurements could be accounted for via a single point outside-field calibration per each beam quality. With further development the KCl:Eu2+--based dosimeter could become a versatile and durable dosimetry tool with large dynamic range (sub-cGy to 100 Gy).

Li, H. Harold; Xiao, Zhiyan; Hansel, Rachael; Knutson, Nels; Yang, Deshan

2013-06-01

78

Performance of KCl:Eu2+ storage phosphor dosimeters for low dose measurements  

PubMed Central

Recent research has demonstrated that europium doped potassium chloride (KCl:Eu2+) storage phosphor material has the potential to become the physical foundation of a novel and reusable dosimetry system using either film-like devices or devices similar to thermoluminescent dosimeter (TLD) chips. The purposes of this work are to quantify the performance of KCl:Eu2+ prototype dosimeters for low dose measurements and to demonstrate how it can be incorporated into clinical application for in vivo peripheral dose measurements. Pellet-style KCl:Eu2+ dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The dosimeters were read using a laboratory photostimulated luminescence detection system. KCl:Eu2+ prototype storage phosphor dosimeter was capable of measuring a dose-to-water as low as 0.01 cGy from a 6 MV photon beam with a signal-to-noise ratio greater than 6. A pre-readout thermal annealing procedure enabled the dosimeter to be read within an hour post irradiation. After receiving large accumulated doses (~10 kGy), the dosimeters retained linear response in the low dose region with only a 20 percent loss of sensitivity comparing to a fresh sample (zero Gy history). The energy-dependence encountered during low dose peripheral measurements could be accounted for via a single point outside-field calibration per each beam quality. With further development the KCl:Eu2+? based dosimeter could become a versatile and durable dosimetry tool with large dynamic range (sub-cGy to 100 Gy). PMID:23735856

Li, H. Harold; Hansel, Rachael; Knutson, Nels; Yang, Deshan

2013-01-01

79

Effect of KCl substitution on bacterial viability of Escherichia coli (ATCC 25922) and selected probiotics.  

PubMed

Excessive intake of NaCl has been associated with the increased risk of several diseases, particularly hypertension. Strategies to reduce sodium intake include substitution of NaCl with other salts, such as KCl. In this study, the effects of NaCl reduction and its substitution with KCl on cell membranes of a cheese starter bacterium (Lactococcus lactis ssp. lactis), probiotic bacteria (Bifidobacterium longum, Lactobacillus acidophilus, and Lactobacillus casei), and a pathogenic bacterium (Escherichia coli) were investigated using Fourier-transform infrared (FTIR) spectroscopy. A critical NaCl concentration that inhibited the viability of E. coli without affecting the viability of probiotic bacteria significantly was determined. To find the critical NaCl concentration, de Man, Rogosa, and Sharpe (MRS) broth was supplemented with a range of NaCl concentrations [0 (control), 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0%], and the effect on cell viability and FTIR spectra was monitored for all bacteria. A NaCl concentration of 2.5% was found to be the critical level of NaCl to inhibit E. coli without significantly affecting the viability of most of the probiotic bacteria and the cheese starter bacterium. The FTIR spectral analysis also highlighted the changes that occurred mainly in the amide regions upon increasing the NaCl concentration from 2.5 to 3.0% in most of the bacteria. Escherichia coli and B. longum were more sensitive to substitution of NaCl with KCl, compared with Lb. acidophilus, Lb. casei, and Lc. lactis ssp. lactis. To evaluate the effect of substitution of NaCl with KCl, substitution was carried out at the critical total salt concentration (2.5%, wt/vol) at varying concentrations (0, 25, 50, 75, and 100% KCl). The findings suggest that 50% substitution of NaCl with KCl, at 2.5% total salt, could inhibit E. coli without affecting the probiotic bacteria. PMID:25064650

Gandhi, Akanksha; Cui, Yuxiang; Zhou, Mingyang; Shah, Nagendra P

2014-10-01

80

Infrared and Raman spectra of [Re(CN)5NO]3- complex isolated in KCl matrix  

NASA Astrophysics Data System (ADS)

We report here the infrared and Raman spectra of [Re(CN)5NO]3- complex as guest diluted in the KCl crystal lattice. According to the chemical analysis, the anion concentration in the KCl host matrix is in excess of 2% (in mole). The solid state Raman spectrum of this complex is reported for the first time. The information obtained from the relative intensities of infrared and Raman bands affords a reexamination of vibration mode assignments. The observed bands splitting may be explained by the interactions of the guest complex with the host lattice, including the ways in which the K+ vacancies are distributed around [Re(CN)5NO]3- to achieve lattice charge neutrality.

Verón, M. G.; Castañeda Trujillo, L. D.; Piro, O. E.; Güida, J. A.

2014-11-01

81

Volume properties of melts of the KF-KCl-HfF/sub 4/ system  

SciTech Connect

Starting salts of purity grade cp were prepared; the hafnium fluoride was purified by double vacuum distillation. Experimental data were reduced using the method of least squares; results are presented for the measurements of the density of the fused mixtures of the KF-KCl-HfF/sub 4/. The highest concentration of hafnium fluoride in the mixtures was limited to 50 mole % due to the increase in the compressibility of its vapor. The density of the fused KF-KCl-HfF/sub 4/ salt mixtures increased with increased hafnium fluoride content. The concentrational dependence of the excess molar volumes is complex and indicates that on mixing the three components in the fused state, the interaction among the components is more complicated than for gas-phase interactions.

Darienko, S.E.; Katyshev, S.F.; Chervinskii, Yu.F.

1988-01-10

82

Electrochemical study of uranium cations in LiCl-KCl melt using a rotating disk electrode  

SciTech Connect

A rotating disk electrode (RDE) measurement technique was employed to investigate the electrochemical REDOX reactions of actinide (An) and lanthanide (Ln) ions in LiCl-KCl molten salt. By using RDE, it is possible to access more exact values of the diffusion coefficient, Tafel slope, and exchange current density. In this work, we constructed RDE setup and electrodes for RDE measurements in high temperature molten salt and measured the electrochemical parameters of the An and Ln ions. The RDE setup is composed of a Pine model MSRX rotator equipped with a rod type of W electrode. The active electrode area was confined to the planar part of the W rod by making meniscus at the LiCl-KCl melt surface.

Bae, Sang-Eun; Kim, Dae-Hyun; Kim, Jong-Yoon; Park, Tae-Hong; Cho, Young Hwan; Yeon, Jei-Won; Song, Kyuseok [Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute,989-111 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2013-07-01

83

The role of valence-band excitation in laser ablation of KCl  

NASA Technical Reports Server (NTRS)

We present recent measurements of excited-atom and ion emission from KCl surfaces illuminated by vacuum-ultraviolet synchrotron radiation (h-nu = 8-28 eV) and ultraviolet laser light (h-nu = 4 eV). At low intensities characteristic of the synchrotron experiments, excited atoms are desorbed by simple valence-band excitation process involving the metallization of the KCl surface. At the higher intensities typical of laser desorption and ablation, we observe a strong decrease in K emission as a function of the number of laser shots, but an essentially constant yield of Cl. K(+) and Cl(-) emission at high intensities show similar behavior. The energetics of these desorption phenomena can be treated in a bond-orbital model which shows that creation of a single valence hole is sufficient to excite an ion to an anti-bonding state.

Haglund, Richard F., Jr.; Tang, Kai; Bunton, Patrick H.; Wang, Ling-Jun

1991-01-01

84

Phase relations in the hydrous CMAS pyrolite in presence of KCl at 2 GPa  

NASA Astrophysics Data System (ADS)

In the upper mantle, chlorides are constituents of concentrated aqueous solutions (brines), as well as chloride-carbonate and carbonatite melts. Mineral assemblages coming from diverse depth levels show that mobile (K, Na)Cl-bearing fluids are able to provoke intensive metasomatism of the peridotitic mantle accompanied by melting. Scarce experimental studies on influence of brines on mineral equilibria in the peridotitic mantle (Stalder et al., 2008; Chu et al., 2011) indicate that influence of chlorides on water activity in a fluid equilibrated with forsterite enstatite at pressures above 2 GPa is very similar to their effect at lower "crustal" pressures (e.g. Aranovich, Newton, 1997): decrease of the H2O activity with an increase of the salt content results in an increase of the melting temperature of silicates. Nevertheless, these experiments were performed in the Al-free systems. Presence of Al would provoke an active interaction of alkali chlorides, namely KCl, with silicates with formation of new K-Al-bearing phases, such as phlogopite (in presence of H2O), which would influence on the melting of complex assemblages. In order to investigate an effect of KCl on phase relations in the Al2O3, CaO, Na2O-rich hydrous peridotite and on stability of garnet, pyroxenes, and amphiboles, in particular, experiments on interaction of the model CMAS pyrolite Fo57En17Prp14Di12 (+0.3 wt. % of Na2O) with the H2O-KCl fluid were performed at 2 GPa in the temperature interval 900-1200. Mixtures of synthetic forsterite, diopside, enstatite and pyrope in the above weight ratio were mixed with 14 wt. % of Mg(OH)2 corresponding to 4.4 wt. % of H2O in the system. 2.4, 3.7, 5 and 10 wt. % of KCl were added to silicate-H2O mixture. Experiments were performed using a piston-cylinder apparatus with ½-inch talc high-pressure cells calibrated via brucite = periclase + H2O and albite = jadeite + quartz equilibria curves. Temperature was controlled with accuracy ?1 with the W95Re5/W80Re20 thermocouple. Spherical and tube Pt capsules with 0.2 mm-thick walls were used in the experiments. Run products were analyzed using CamScan MV2300 (VEGA TS 5130MM) electron microscope equipped with EDS INCA-Energy-250. The subsolidus assemblage of the model pyrolite (< 1025OC) containing 4.4 wt. % of H2O at 2.5 GPa includes forsterite (Fo), low-Al2O3 (below 0.5 wt. %) clinopyroxene (Cpx), orthopyroxene (Opx) with up to 7 wt. % of Al2O3, pargasite-tschermackite amphibole (Amp), pyrope-grossular garnet (Grt), and minute spinel (Spl). It is consistent with the results of experiments with amphibole-bearing lherzolite (e.g. Niida, Green, 1999). Reaction relations 3/2Opx + 1/2Fo + 1/2Amp = Grt + Cpx + 1/2H2O are observed in the run samples. Melting apparently begins in the temperature interval 1025-1050 and results in gradual disappearance of amphibole. In general, similar relations are available in presence of 2.4 wt. % of KCl. However, reaction 6Opx + Fo + Amp + KCl = [Cl-Phl + Phl] + Grt + 2Cpx results in formation of Cl-bearing phlogopite solid solution, Phl (up to 1 wt. % of Cl). It seems to be stable at higher temperatures (apparently, above 1200) with respect to amphibole, consistently with the experimental data on melting of phlogopite and amphibole-bearing peridotites at pressures >1.5 GPa (Modreski, Boettcher, 1973; Mysen, Boettcher, 1975; Mengel, Green, 1989). Garnet, orthopyroxene, and amphibole, i.e. all alumina-rich phases of the "starting" KCl-free peridotite, are totally disappear with addition of 3.7 wt. % and more of KCl, while the assemblage of Cl-bearing phlogopite with Al-poor clinopyroxene and olivine is stable. The solidus temperature of the H2O-bearing pyrolite with addition of KCl is about 900 at 2.4 wt.% of KCl and seems to be much lower at 10 wt. % of KCl. Anyway, these temperatures are more than by 100 lower of the melting temperature of the H2O-bearing pyrolite without KCl, as well as Cl-free Di+Phl assemblage (Modreski, Boettcher, 1973). Apparently, decrease of the temperature is related to solubility of Cl in

Safonov, O.

2012-04-01

85

Temperature dependence of the photostimulated luminescence in KCl:Eu2+  

NASA Astrophysics Data System (ADS)

The goal of this work is to understand the physical mechanism behind the signal stabilization process in KCl:Eu2+, a storage phosphor material that has generated renewed interest due to its potential in radiation therapy dosimetry application. The temperature dependency of the photostimulated luminescence (PSL) spectra and intensity vs. time post X-ray irradiation was measured. Commercial BaFBr:Eu2+ materials were included in this study for comparison. Unlike BaFBr:Eu2+, broadening of the F(Cl-) stimulation band and red-shift of the peak were observed for KCl:Eu2+ with increasing temperature. For irradiations at temperatures lower than 200 K, PSL intensity of KCl:Eu2+ showed recuperation behavior in the first 2 h post-irradiation and stayed almost constant with time thereafter. Moreover, spatially-correlated storage centers increased from 24% for irradiation at 50 K to 31% at 195 K and almost 100% at room temperature. The data suggest that certain types of charge storage-centers were mobile and contribute to the fast fading in PSL.

Xiao, Zhiyan; Hansel, Rachael; Zhang, Lei; Li, H. Harold

2014-05-01

86

X-ray storage performance of KCl:Eu2+ with high cumulated dose  

NASA Astrophysics Data System (ADS)

The effects of high cumulative radiation dose on the luminescence properties of KCl:Eu2+ are investigated. Pellet samples of KCl:Eu2+ were given doses of up to 200 kGy at the Louisiana State University Synchrotron facility. After synchrotron irradiation, samples were optically bleached and given a clinical dose of 2 Gy from a 6 MV medical linear accelerator. Optical properties were evaluated using photostimulated luminescence (PSL), photoluminescence (PL), and temperature-dependent PSL measurements. For a cumulated dose of up to 5-10 kGy, the PSL emission intensity increased by 15% compared to the PSL signal with no radiation history. For doses higher than 10 kGy, the PSL emission intensity retained at least 70% of the original intensity. Spatial correlation of the charge storage centers increased for doses up to 5 kGy and then decreased for higher cumulative doses. Emission band at 975 nm was attributed to transitions of Eu1+. PL spectra showed an intense peak centered at 420 nm for all cumulative doses. The results of this work show that KCl:Eu2+ storage phosphors are excellent reusable materials for radiation therapy dosimetry.

Hansel, Rachael A.; Xiao, Zhiyan; Zhang, Lei; Li, H. Harold

2014-05-01

87

Supercooling of aqueous NaCl and KCl solutions under acoustic levitation.  

PubMed

The supercooling capability of aqueous NaCl and KCl solutions is investigated at containerless state by using acoustic levitation method. The supercooling of water is obviously enhanced by the alkali metal ions and increases linearly with the augmentation of concentrations. Furthermore, the supercooling depends on the nature of ions and is 2-3 K larger for NaCl solution than that for KCl solution in the present concentration range: Molecular dynamics simulations are performed to reveal the intrinsic correlation between supercoolability and microstructure. The translational and orientational order parameters are applied to quantitatively demonstrate the effect of ionic concentration on the hydrogen-bond network and ice melting point. The disrupted hydrogen-bond structure determines essentially the concentration dependence of supercooling. On the other hand, the introduced acoustic pressure suppresses the increase of supercooling by promoting the growth and coalescence of microbubbles, the effective nucleation catalysts, in water. However, the dissolved ions can weaken this effect, and moreover the degree varies with the ion type. This results in the different supercoolability for NaCl and KCl solutions under the acoustic levitation conditions. PMID:17042605

Lü, Y J; Wei, B

2006-10-14

88

Proteolysis of low-moisture Mozzarella cheese as affected by substitution of NaCl with KCl.  

PubMed

The proteolytic and ACE inhibitory activities of low-moisture Mozzarella cheese (LMMC) as affected by partial substitution of NaCl with KCl were investigated. Experimental LMMC were made and salted with 4 salt mixtures: NaCl only (control), 3NaCl:1KCl, 1NaCl:1KCl, and 1NaCl:3KCl, and then proteolytic activity and angiotensin-converting enzyme inhibitory activity were determined. Salt treatment significantly affected angiotensin-converting enzyme inhibitory activity and phosphotungstic acid-soluble N of LMMC during storage. Water-soluble N, trichloroacetic acid-soluble N, lactic acid bacteria population, and total free amino acids were unaffected during storage. Nonetheless, water-soluble N and trichloroacetic acid-soluble N increased significantly during storage within a salt treatment. Peptide profiles and urea-PAGE gels did not differ between experimental cheeses at the same storage time. PMID:21787913

Ayyash, M M; Shah, N P

2011-08-01

89

Temporal signal stability of KCl:Eu{sup 2+} storage phosphor dosimeters  

SciTech Connect

Purpose: Current KCl:Eu{sup 2+} prototype dosimeters require a wait time of 12 h between irradiation and dosimetric readout. Although irradiating the dosimeters in the evening and reading on the following day works well in the clinical schedule, reducing the wait time to few hours is desirable. The purposes of this work are to determine the origin of the unstable charge-storage centers and to determine if these centers respond to optical or thermal excitation prior to dosimetric readout. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters were fabricated in-house for this study. A 6 MV photon beam was used to irradiate the dosimeters. After x ray irradiation, dosimeters were subjected to external excitation with near-infrared (NIR) light, ultraviolet (UV) light, or thermal treatment. Photostimulated luminescence (PSL) signal's temporal stability was subsequently measured at room temperature over a few hours using a laboratory PSL readout system. The dosimeters were also placed in a cryostat to measure the temperature dependence of the temporal stability down to 10 K. Results: Strong F-band was present in the PSL stimulation spectrum, indicating that F-centers were the electron-storage centers in KCl:Eu{sup 2+} where an electron was stored at a chlorine anion vacancy. Due to deep energy-depth (2.2 eV), F-centers were probably not responsible for the fast fading in the first a few hours post x ray irradiation. In addition, weak NIR bands were present. However, there was no change in PSL stabilization rate with intense NIR excitation, suggesting that the NIR bands played no role in the PSL fading. At temperatures lower than 77 K there was almost no signal fading with time. Noticeable PSL was observed for undoped KCl samples at room temperature, suggesting that Cl{sub 2}{sup -} V{sub k} centers served as hole-storage centers for both undoped and doped KCl where a hole was trapped by a chlorine molecular ion. V{sub k} centers were stable at low temperature and became mobile at room temperature, probably causing the observed PSL fading with time. On the other hand, V{sub k} center could be stabilized by Eu{sup 2+} activator or oxygen in the lattice, leading to the stable component in the PSL. A thermal process at elevated temperatures (60 Degree-Sign C or higher) was able to significantly accelerate the migration process resulting in a fast stabilization of PSL. However, this could not be accomplished using intense UV excitation. Conclusions: Thermal treatment enables KCl:Eu{sup 2+} prototypes to be ready for readout in 1 h without the need of applying a large time-dependent correction factor. However, this cannot be achieved using optical preexcitation.

Xiao Zhiyan; Hansel, Rachael; Chen Haijian; Du Dongsu; Yang Deshan; Li, H. Harold [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)

2013-02-15

90

Thermal Properties of LiCl-KCl Molten Salt for Nuclear Waste Separation  

SciTech Connect

This project addresses both practical and fundamental scientific issues of direct relevance to operational challenges of the molten LiCl-KCl salt pyrochemical process, while providing avenues for improvements in the process. In order to understand the effects of the continually changing composition of the molten salt bath during the process, the project team will systematically vary the concentrations of rare earth surrogate elements, lanthanum, cerium, praseodymium, and neodymium, which will be added to the molten LiCl-KCl salt. They will also perform a limited number of focused experiments by the dissolution of depleted uranium. All experiments will be performed at 500 deg C. The project consists of the following tasks. Researchers will measure density of the molten salts using an instrument specifically designed for this purpose, and will determine the melting points with a differential scanning calorimeter. Knowledge of these properties is essential for salt mass accounting and taking the necessary steps to prevent melt freezing. The team will use cyclic voltammetry studies to determine redox potentials of the rare earth cations, as well as their diffusion coefficients and activities in the molten LiCl-KCl salt. In addition, the team will perform anodic stripping voltammetry to determine the concentration of the rare earth elements and their solubilities, and to develop the scientific basis for an on-line diagnostic system for in situ monitoring of the cation species concentration (rare earths in this case). Solubility and activity of the cation species are critically important for the prediction of the salt's useful lifetime and disposal.

Sridharan, Kumar [Univ. of Wisconsin, Madison, WI (United States); Allen, Todd [Univ. of Wisconsin, Madison, WI (United States); Anderson, Mark [Univ. of Wisconsin, Madison, WI (United States); Simpson, Mike [Idaho National Lab., (United States)

2012-11-30

91

Temperature dependence of fluorescence for EuCl3 in LiCl-KCl eutectic melt.  

PubMed

The fluorescence of EuCl(3) in LiCl-KCl eutectic melt according to temperature changes was investigated, and the spontaneous partial reduction of Eu(3+) to Eu(2+) at high temperature was confirmed by the fluorescence results. The fluorescence decreases when the temperature increases, and this was examined in detail. The studies of fluorescence provided information regarding the chemical and physical behavior of europium ions in the molten salt according to the temperature changes. It is applicable for monitoring species and concentrations and estimating the approximate chemical structure of the ions in molten salts. PMID:20678668

Im, Hee-Jung; Kim, Tack-Jin; Song, Kyuseok

2010-08-15

92

Trends in Resin and KCl-extractable Soil Nitrogen Across Landscape Gradients in Taylor Valley, Antarctica  

Microsoft Academic Search

Previous descriptions of soils in the McMurdo Dry Valleys, Antarctica, have focused on the dominance of abiotic controls rather\\u000a than on nutrient cycling. Although free-living N2-fixing and nitrifying microorganisms have been isolated in Antarctic soils, little is known about in situ nitrogen (N) cycling.\\u000a We measured KCl-extractable NH4\\u000a + and NO3\\u000a –, as well as anion resin exchangeable NO3\\u000a –,

John E. Barrett; Ross A. Virginia; Diana H. Wall

2002-01-01

93

A light induced configurational change of FA centres in Li doped KCl-KBr crystals  

NASA Astrophysics Data System (ADS)

Spectroscopic properties of FA centres in Li doped KCl-KBr mixed crystals were studied. At low temperature light induced spectral shifts, for the FA1 hand towards lower energy and for the FA2 band towards higher energy, were observed. The shifts are proposed to be due to a configurational change where the electron occupied vacancy finds a new location in relation to the neighbouring chlorine and bromine ions. The recovery to the original configuration, obtained in the F ? FA conversion, is a temperature activated process.

Ketolainen, P.; Silfsten, P.

1995-12-01

94

Deposition studies of lithium and bismuth at tungsten microelectrodes in LiCl:KCl eutectic  

NASA Astrophysics Data System (ADS)

Tungsten microelectrodes (diam = 25 microns) have been used to study the deposition and stripping behavior of Li/Li(+) and Bi/Bi(3+) in the LiCl:KCl eutectic at 400 C. The Li deposition current can be simulated assuming the growth of a single hemisphere of liquid metal on the microelectrode. High stripping current densities were observed and quantitated using standard electrochemical equipment. An inverted microscope assembly was employed for in situ observation of the Li/Li(+) deposition and stripping processes at the microelectrode. A precipitate appears to form in the melt surrounding the electrode during Li deposition.

Carlin, Richard T.; Osteryoung, Robert A.

1989-05-01

95

An investigation of the critical liquid-vapor properties of dilute KCl solutions  

USGS Publications Warehouse

The three parameters that define the critical point, temperature, pressure, and volume have been experimentally determined by means of filling studies in a platinum-lined system for five KCl solutions ranging from 0.006 to 0.568 m. The platinum-lined vessels were used to overcome the problems with corrosion experienced by earlier workers. The critical temperature (tc), pressure (Pc), and volume (Vc) were found to fit the equations {Mathematical expression} from infinite dilution to 1.0 m. ?? 1976 Plenum Publishing Corporation.

Potter, R.W., II; Babcock, R.S.; Czamanske, G.K.

1976-01-01

96

Effects of fully and partial substitution of NaCl by KCl on physico-chemical and sensory properties of white pickled cheese.  

PubMed

White pickled cheeses were produced with different salting treatments, vacuum-packed in polyethylene containers, and stored at 4 +/- 1 degree C for 90 days. Five different concentrations of NaC1, KC1 or NaCl/KCl mixtures (sample A, 100% NaCl; sample B, 100% KCl; sample C, 75% NaCl + 25% KCl; sample D, 50% NaC1+50% KCl; sample E, 25% NaCl+75% KCl) were applied in the production of cheeses. Some physical, chemical and sensory properties of the samples were monitored at 0, 15, 30, 60 and 90 days of ripening. The results obtained indicated that the cheese could be produced with the mixture of 75% NaCl + 25% KCl without negative effects on cheese quality. PMID:17852492

Karagözlu, Cem; Kinik, Ozer; Akbulut, Necati

2008-05-01

97

A simplified model of TiH1.65/KClO4 pyrotechnic ignition.  

SciTech Connect

A simplified model was developed and is presented in this report for simulating thermal transport coupled with chemical reactions that lead to the pyrotechnic ignition of TiH1.65/KClO4 powder. The model takes into account Joule heating via a bridgewire, thermal contact resistance at the wire/powder interface, convective heat loss to the surroundings, and heat released from the TiH1.65- and KClO4-decomposition and TiO2-oxidation reactions. Chemical kinetic sub-models were put forth to describe the chemical reaction rate(s) and quantify the resultant heat release. The simplified model predicts pyrotechnic ignition when heat from the pyrotechnic reactions is accounted for. Effects of six key parameters on ignition were examined. It was found that the two reaction-rate parameters and the thermal contact resistance significantly affect the dynamic ignition process whereas the convective heat transfer coefficient essentially has no effect on the ignition time. Effects of the initial/ambient temperature and electrical current load through the wire are as expected. Ignition time increases as the initial/ambient temperature is lowered or the wire current load is reduced. Lastly, critical needs such as experiments to determine reaction-rate and other model-input parameters and to measure temperature profiles, time to ignition and burn-rate data for model validation as well as efforts in incorporating reaction-rate dependency on pressure are pointed out.

Chen, Ken Shuang

2009-04-01

98

Effect of Aluminum Particle Surface Area and Morphology on the Combustion Properties of KClO4/Al Compositions  

NASA Astrophysics Data System (ADS)

Compositions of KClO4/Al are used in military applications as well as the pyrotechnics industry. The reaction rate as well as the ease of initiation depends on metal particle surface area as well as particle morphology. This factor is especially important for metal fuels having a melting point higher than the melting point of the oxidizer component in the energetic composition. Aluminum powder and turnings of various particle sizes were combined with KClO4 to form an energetic composition. The explosives mixtures were combusted in a rapid scanning calorimeter device (RSD). dP/dt and dT/dt results were measured and heats of reaction were calculated. The effect of Al particle surface area and particle morphology on the combustion properties of KClO4/Al is discussed.

Caulder, Stanley; Mackey, Joseph; Wilkinson, John

2009-06-01

99

Computer simulation of electron states of the isoelectronic substitutional impurities in quantum wire of KCl with edge dislocation  

NASA Astrophysics Data System (ADS)

The electron states of quantum wires KCl, KCl : Br, and KCl : I with an edge dislocations were investigated. The main problem was in study of dislocation influence on localized electron states connected with substitutional isoelectronic impurities Br? and I? in the neighborhood of edge dislocation line. The tight-binding semi-empirical band approximation, semi-empirical and non-empirical cluster approach were used. Semi-empirical calculations were carried out in framework of model [1,2]. Besides, the algorithms for electronic levels calculations of polar nanosystems with the partial self-consistency [3] were used. The computer simulation results lead to the conclusion that the substitutional isoelectronic impurity anions Br? and I? located near the dislocation line capture the holes more efficiently than in bulk of systems without dislocations.

Timoshenko, Yury K.; Shunina, Valentina A.; Shashkin, Alexander I.

2015-01-01

100

Urea and KCl have differential effects on enzyme activities in liver and muscle of estivating versus nonestivating species.  

PubMed

The effects of 300 mM urea or 300 mM KCl on the maximal activities of 25 enzymes of intermediary metabolism were assessed in extracts of liver and muscle from spadefoot toads (Scaphiopus couchii), leopard frogs (Rana pipiens), and rats to assess their sensitivity to these osmolytes. During estivation, toads can lose -50% of total body water, and urea, which is known for its action as a protein denaturant, accumulates to 200-300 mM. The data show that the maximal activities of toad liver enzymes were not affected when assayed in the presence of 300 mM urea in vitro whereas urea inhibited the activities of seven enzymes in frog and 11 enzymes in rat liver. High KCl affected 12 or 13 enzymes in liver of each species causing inhibition in eight or nine cases each, and for frog and rat enzymes, inhibition was frequently more pronounced than for urea. Both urea and KCl affected enzyme activities in muscle extracts of all three species, but whereas their effects were largely negative for frog and rat enzymes, the enzymes affected by urea or KCl in toad muscle were primarily activated by these osmolytes (six out of nine enzymes affected by urea and eight of 15 enzymes affected by KCl). Urea, KCl, and polyethylene glycol (a protein crowding agent) also had species-specific effects on the dissociation constant (Ka) for cAMP of protein kinase A. The data suggest that the accumulation of urea by water-stressed anurans not only contributes to minimizing cell volume reduction, but by doing so also limits the increase in intracellular ionic strength that occurs and thereby helps to minimize the potential inhibitory effects of high salts on metabolic enzymes. PMID:12555807

Cowan, Kyra J; Storey, Kenneth B

2002-01-01

101

(C6H14N2)2[VO(HPO4)5B2O] x H2O x -H3PO4, a novel borophosphate cluster containing a single vanadium centre and linked by hydrogen bonds into a three-dimensional framework.  

PubMed

The title novel vanadium borophosphate compound, bis(1,4-diazonia[2.2.2]octane) mu(3)-oxo-oxopenta-mu-phosphato-diboronvanadium monohydrate phosphoric acid solvate, containing the cluster anion [VO(PO(3)OH)(5)B(2)O](4-), has been synthesized under mild hydrothermal conditions. Extensive O-H...O and N-H...O hydrogen bonding is observed between the molecular units. PMID:12711766

Wikstad, Emma; Kritikos, Mikael

2003-03-01

102

Modulation of neuronal activity by phosphorylation of the K–Cl cotransporter KCC2  

PubMed Central

The K–Cl cotransporter KCC2 establishes the low intraneuronal Cl? levels required for the hyperpolarizing inhibitory postsynaptic potentials mediated by ionotropic g-aminobutyric acid receptors (GABAARs) and glycine receptors (GlyRs). Decreased KCC2-mediated Cl? extrusion and impaired hyperpolarizing GABAAR- and/or GlyR-mediated currents have been implicated in epilepsy, neuropathic pain, and spasticity. Recent evidence suggests that the intrinsic ion transport rate, cell surface stability, and plasmalemmal trafficking of KCC2 are rapidly and reversibly modulated by the (de)phosphorylation of critical serine, threonine, and tyrosine residues in the C terminus of this protein. Alterations in KCC2 phosphorylation have been associated with impaired KCC2 function in several neurological diseases. Targeting KCC2 phosphorylation directly or indirectly via upstream regulatory kinases might be a novel strategy to modulate GABA- and/or glycinergic signaling for therapeutic benefit. PMID:24139641

Silayeva, Liliya; Liang, Bo; Kaila, Kai; Moss, Stephen J.

2015-01-01

103

KA2 and KA1 bands in FA(II) KCl:Li crystals  

NASA Astrophysics Data System (ADS)

The strong dichroism photoinduced in an FA(II) KCl:Li crystal by radiation belonging only to the K band shows the writing anisotropy of this band. We suggest that the K band of FA centers is formed of two bands, KA1 and KA2, which characterize the transitions parallel to the axis of the center and the transitions polarized in a plane perpendicular, respectively. By numerically deconvolving the measured spectra of dichroism and assuming a Gaussian law for the dispersion of the absorption cross sections, we obtain the parameters of these two bands and demonstrate that their half-maximum widths vary as those of the FA1 and FA2 bands versus temperature.

May, Marie; Debrus, Solange; Quernet, Bruno

1991-02-01

104

Growth and characterization of pure and KCl doped zinc thiourea chloride (ZTC) single crystals  

NASA Astrophysics Data System (ADS)

Potassium Chloride (KCl) as an additive is added into zinc thiourea chloride solution in a small amount (1 M%) by the method of slow evaporation solution growth technique at room temperature to get a new crystal. Due to the doping of the impurities on the crystals, remarkable changes in the physical properties were obtained. The grown crystals have been subjected to different instrumentation methods. The incorporation of the amount of potassium and zinc in the crystal lattices has been determined by AAS method. The lattice dimensions have been identified from single crystal X-ray diffraction measurements. The presence of functional group for the grown crystals has been identified by FTIR analysis. The optical, thermal and mechanical behaviors have been assessed by UV-Vis, TG/DTA and Vickers hardness methods respectively. The presence of dislocations of atoms has been identified by etching studies.

Ruby Nirmala, L.; Thomas Joseph Prakash, J.

2013-02-01

105

Growth and characterization of pure and KCl doped zinc thiourea chloride (ZTC) single crystals.  

PubMed

Potassium Chloride (KCl) as an additive is added into zinc thiourea chloride solution in a small amount (1M%) by the method of slow evaporation solution growth technique at room temperature to get a new crystal. Due to the doping of the impurities on the crystals, remarkable changes in the physical properties were obtained. The grown crystals have been subjected to different instrumentation methods. The incorporation of the amount of potassium and zinc in the crystal lattices has been determined by AAS method. The lattice dimensions have been identified from single crystal X-ray diffraction measurements. The presence of functional group for the grown crystals has been identified by FTIR analysis. The optical, thermal and mechanical behaviors have been assessed by UV-Vis, TG/DTA and Vickers hardness methods respectively. The presence of dislocations of atoms has been identified by etching studies. PMID:23220671

Ruby Nirmala, L; Thomas Joseph Prakash, J

2013-02-01

106

Calorimetric study of the entropy relation in the NaCl–KCl system  

PubMed Central

The heat capacity of one Na-rich and two K-rich samples of the NaCl–KCl (halite–sylvite) crystalline solution was investigated between 5 and 300 K. It deviated positively from ideal behaviour with a maximum at 40 K. The thereby produced excess entropy at 298.15 K was described by a symmetric Margules mixing model yielding WmS = 8.73 J/mol/K. Using enthalpy of mixing data from the literature and our data on the entropy, the solvus was calculated for a pressure of 105 Pa and compared with the directly determined solvus. The difference between them can be attributed to the effect of Na–K short range ordering (clustering). PMID:24926102

Benisek, Artur; Dachs, Edgar

2013-01-01

107

Calorimetric study of the entropy relation in the NaCl-KCl system.  

PubMed

The heat capacity of one Na-rich and two K-rich samples of the NaCl-KCl (halite-sylvite) crystalline solution was investigated between 5 and 300 K. It deviated positively from ideal behaviour with a maximum at 40 K. The thereby produced excess entropy at 298.15 K was described by a symmetric Margules mixing model yielding [Formula: see text] = 8.73 J/mol/K. Using enthalpy of mixing data from the literature and our data on the entropy, the solvus was calculated for a pressure of 10(5) Pa and compared with the directly determined solvus. The difference between them can be attributed to the effect of Na-K short range ordering (clustering). PMID:24926102

Benisek, Artur; Dachs, Edgar

2013-07-01

108

Thermal positive ion production from KCl impinging upon Re: Comparison between theory and experiment  

SciTech Connect

On the basis of our theory on thermal ionization, the emission current of K/sup +/ ions produced from KCl molecules incident upon a polycrystalline rhenium surface is calculated as a function of surface temperature in the range 950--2100 K. Theoretical results thus obtained are in good agreement with experimental data. This agreement gives an additional evidence for our previous conclusions that below approx.1800 K the work function of the surface is increased from 5.5 up to approx.7 eV mainly by adsorption of residual gas molecules at approx.2 x 10/sup -7/ Torr and also that the dissociation of incident sample molecules is greatly promoted by the work function increase.

Kawano, H.; Kenpo, T.

1984-12-20

109

Development of high temperature transport technology for LiCl-KCl eutectic salt in pyroprocessing  

SciTech Connect

The development of high-temperature transport technologies for molten salt is a prerequisite and a key issue in the industrialization of pyro-reprocessing for advanced fuel cycle scenarios. The solution of a molten salt centrifugal pump was discarded because of the high corrosion power of a high temperature molten salt, so the suction pump solution was selected. An apparatus for salt transport experiments by suction was designed and tested using LiC-KCl eutectic salt. The experimental results of lab-scale molten salt transport by suction showed a 99.5% transport rate (ratio of transported salt to total salt) under a vacuum range of 100 mtorr - 10 torr at 500 Celsius degrees. The suction system has been integrated to the PRIDE (pyroprocessing integrated inactive demonstration) facility that is a demonstrator using non-irradiated materials (natural uranium and surrogate materials). The performance of the suction pump for the transport of molten salts has been confirmed.

Lee, Sung Ho; Lee, Hansoo; Kim, In Tae; Kim, Jeong-Guk [Korea Atomic Energy Research Institute, 1045 Daedeok-daaro, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2013-07-01

110

Corrosion resistance of steel materials in LiCl-KCl melts  

NASA Astrophysics Data System (ADS)

The corrosion behaviors of 304SS, 316LSS, and Q235A in LiCl-KCl melts were investigated at 450°C by Tafel curves and electrochemical impedance spectroscopy (EIS). 316LSS shows the best corrosion resistance behaviors among the three materials, including the most positive corrosion potential and the smallest corrosion current from the Tafel curves and the largest electron transfer resistance from the Nyquist plots. The results are in good agreement with the weight losses in the static corrosion experiments for 45 h. This may be attributed to the better corrosion resistance of Mo and Ni existing as alloy elements in 316LSS, which exhibit the lower corrosion current densities and more positive corrosion potentials than 316LSS in the same melts.

Wang, Le; Li, Bing; Shen, Miao; Li, Shi-yan; Yu, Jian-guo

2012-10-01

111

Molecular identification of K-CL cotransporter in dog erythroid progenitor cells.  

PubMed

KCC1 cDNA was cloned in dog erythroblasts that had differentiated from peripheral mononuclear cells. The size of the cDNA was 3,258 bp, the same as in pigs, but 3 bp longer than in humans and rodents. The dog KCC1 cDNA encodes for 1,086 amino acid residues with a calculated molecular mass of 120 kDa. The 560 bp cDNA fragment from position 679 to 1,238 in the full length cDNA from the dog erythroblasts was 100% identical to that in the kidney. Hydropathy analysis showed that the structure of dog KCC1 was similar to in other species; 12 trans membrane domains, four glycosylation sites in loop 5, and 17 consensus phosphorylation sites in the cytosol. However, there were variations in dog KCC1 compared to in other species; there was one CK2 phosphorylation site that was found only in dog KCC1. There were also substitutions of amino acids that affect pH sensitivity (His) and change acidic/basic residues or charged residues. In HEK 293 cells transfected with dog KCC1 cDNA (HEK-dKCC1), the Rb influx, which was ouabain-resistant, Cl-dependent, N-ethyl maleimide (NEM)- stimulative and Na-independent, was measured as for K-Cl cotransport, and the influx was found to be increased approximately 3 fold in HEK-dKCC1 compared to in the control. This ouabain-resistant Cl-dependent Rb influx was also volume-sensitive in hyposmotic medium, and the volume-sensitive component was inhibited by furosemide. Thus, the KCC1 cDNA cloned in dog erythroblasts encodes a volume-sensitive K-Cl cotransporter. PMID:15113835

Ochiai, Hideharu; Higa, Kazunari; Fujise, Hiroshi

2004-03-01

112

Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

2013-02-01

113

Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy landscapes: (KCl)32 and related systems  

E-print Network

Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy Available online 25 November 2011 Keywords: Clusters Interaction potentials Range of interactions Topography for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures

Berry, R. Stephen

114

Development and study of cement and a phosphocalciques ceramic as medical use  

NASA Astrophysics Data System (ADS)

The hydroxyapatite (Ca{10}(PO{4})6(OH){2}) has a structure and a chemical composition very close to those of the mineral phase of calcified tissues. It is thus used for a long time in orthopedic and odontological surgery. In the past few years, cements which evolve toward the hydroxyapatite have been the object of several studies. This communication reports the synthesis and the study of new phosphocalcic cement, which evolves after hardening, towards a hydroxyapatite. The cement is composed of tricalcium phosphate a type (? -Ca{3}(PO{4})2), calcium hydroxide (Ca(OH){2}) and phosphoric acid (H{3}PO{4}). The sintering of hardened cement, leads to ceramics having a structure and chemical composition close to those of the bone's mineral phase. The trisodium phosphate is used as melting agent to increase the hardness of ceramics and to decrease the sintering temperature, without affecting the physicochemical properties of ceramics.

Abbaoui, E.; Essaddek, A.; Mejdoubi, E.; Elansari, L. L.; Elgadi, M.; Hammouti, B.

2005-03-01

115

Corrosion and Microstructure Correlation in Molten LiCl-KCl Medium  

NASA Astrophysics Data System (ADS)

Pyrochemical reprocessing in molten chloride salt medium has been considered as one of the best options for the reprocessing of spent metallic fuels of future fast breeder reactors. The unit operations such as salt preparation, electrorefining, and cathode processing involve the presence of molten LiCl-KCl eutectic salt from 673 to 1373 K (400 to 1100 °C). The present work discusses the corrosion behavior of electroformed nickel (EF Ni) without and with nickel-tungsten (Ni-W) coating, 316L SS, and INCONEL 625 alloy in molten LiCl-KCl eutectic salt at 673 K, 773 K, and 873 K (400 °C, 500 °C, and 600 °C) in the presence of air. The weight percent loss of the exposed samples was determined by the weight loss method and surface morphology of the salt exposed, and product layers were examined by scanning electron microscopy (SEM). X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis were also carried out on the exposed and corrosion product layers to understand the phases present and the corrosion mechanism involved. The results of the present study indicated that INCONEL 625 alloy showed superior corrosion resistance compared to electroformed nickel (EF Ni), EF Ni with nickel-tungsten (Ni-W) coating (EF Ni-W), and 316L SS. The EF Ni with Ni-W coating exhibits better corrosion resistance than EF Ni without tungsten coating. Based on the surface morphology, XRD, and EDX analysis of corrosion product layers, the mechanism of corrosion of INCONEL 625 and 316L involves formation of chromium-rich compound at the surface and subsequent spallation. For the EF Ni, the porous thick NiO corrosion product allows the penetration of salt, thus accelerating the corrosion. Improved corrosion resistance of EF Ni-W was attributed to the W-rich NiO layer, while for INCONEL 625, the adherent and protective NiO layer improved the corrosion resistance. The article highlights the results of the present investigation.

Ravi Shankar, A.; Mathiya, S.; Thyagarajan, K.; Kamachi Mudali, U.

2010-07-01

116

Separation of plutonium from lanthanum by electrolysis in LiCl KCl onto molten bismuth electrode  

NASA Astrophysics Data System (ADS)

This work presents a study on the electroseparation of plutonium from lanthanum using molten bismuth electrodes in LiCl-KCl eutectic at 733 K. The reduction potentials of Pu3+ and La3+ ions were measured on a Bi thin film electrode using cyclic voltammetry (CV). A difference between the peak potentials for the formation of PuBi2 and LaBi2 of approximately 100 mV was found. Separation tests were then carried out using different current densities and salt phase compositions between a plutonium rod anode and an unstirred molten Bi cathode in order to evaluate the efficiency of an electrolytic separation process. At a current density of 12 mA/cm2/wt% (Pu3+), only Pu3+ ions are reduced into the molten Bi electrode, leaving La3+ ions in the salt melt. Similar results were found at two different Pu/La concentration ratios ([Pu]/[La] = 4 and 10). At a current density of 26 mA/cm2/wt% (Pu3+), co-reduction of Pu and La was observed as expected by the large negative potential of the Bi cathode during the separation test.

Serp, J.; Lefebvre, P.; Malmbeck, R.; Rebizant, J.; Vallet, P.; Glatz, J.-P.

2005-04-01

117

On the formation of U Al alloys in the molten LiCl KCl eutectic  

NASA Astrophysics Data System (ADS)

U-Al alloy formation has been studied in the temperature range of 400-550 °C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAl x alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl 3 and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl 2, UAl 3 and UAl 4) depending on the experimental conditions.

Cassayre, L.; Caravaca, C.; Jardin, R.; Malmbeck, R.; Masset, P.; Mendes, E.; Serp, J.; Soucek, P.; Glatz, J.-P.

2008-08-01

118

Protein-salt binding data from potentiometric titrations of lysozyme in aqueous solutions containing KCl  

SciTech Connect

An existing method for potentiometric titrations of proteins was improved, tested and applied to titrations of the enzyme hen-egg-white lysozyme in aqueous solutions containing KCl at ionic strengths from 0.1 M to 2.0 M at 25 C. Information about the protein`s net charge dependence on pH and ionic strength were obtained and salt binding numbers for the system were calculated using a linkage concept. For the pH range 2.5--11.5, the net charge slightly but distinctly increases with increasing ionic strength between 0.1 M and 2.0 M. The differences are most distinct in the pH region below 5. Above pH 11.35, the net charge decreases with increasing ionic strength. Preliminary calculation of binding numbers from titration curves at 0.1 M and 1.0 M showed selective association of chloride anions and expulsion of potassium ions at low pH. Ion-binding numbers from this work will be used to evaluate thermodynamic properties and to correlate crystallization or precipitation phase-equilibrium data in terms of a model based on the integral-equation theory of fluids which is currently under development.

Engmann, J.; Blanch, H.W.; Prausnitz, J.M. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.

1997-03-01

119

Methanol extracts of Hamelia patens containing oxindole alkaloids relax KCl-induced contraction in rat myometrium.  

PubMed

Hamelia patens JAQC. (Rubiaceae) is a medicinal bush widely distributed in tropical areas of the American continent. It is used in Mexican Traditional Medicine for the treatment of menstrual disorders, therefore suggesting that its chemical constituents may have some effect on myometrium contractility. Physiological effects might differ due to quantitative variations in the content of alkaloids arising from its wide geographical distribution. To test this hypothesis, the content of oxindole alkaloids in methanol extracts of five different samples collected in Mexico was quantified by GC-MS. Each extract was assayed on contractility of estrogen-primed rat myometrium. Variations in the content of alkaloids were observed among the different samples. All samples relaxed in a concentration-dependent manner the high KCl-induced contraction in rat myometrium. Those which lack rumberine and/or maruquine displayed a higher relaxant effect than samples containing them, suggesting that these alkaloids might counteract the effects of isopteropodine. However, in contrast with verapamil, Hamelia patens metanol extracts are poor relaxants. PMID:15467206

Reyes-Chilpa, Ricardo; Rivera, Jesús; Oropeza, Martha; Mendoza, Pilar; Amekraz, Badia; Jankowski, Christopher; Campos, Maria

2004-10-01

120

Electrochemical formation of Al-Tm intermetallics in eutectic LiCl-KCl melt containing Tm and Al ions  

NASA Astrophysics Data System (ADS)

This work focuses on investigating the electrochemical formation of Al-Tm and Al-Li-Tm alloys in LiCl-KCl-AlCl3-Tm2O3 melt on both W and Al electrodes. Thermodynamic calculation and electrochemical behavior of LiCl-KCl melt containing both AlCl3 and Tm2O3 showed that AlCl3 can chlorinate Tm2O3 to release Tm(III) ions. Three kinds of Al-Tm intermetallics at about -1.26, -1.32 and -1.43 V were detected by means of various electrochemical measurement techniques, i.e. cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were carried out on Al and W electrodes to prepare Al-Tm and Al-Li-Tm alloys, respectively. The composition of Al-Li-Tm alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES).

Li, Xing; Yan, Yong-De; Zhang, Mi-Lin; Tang, Hao; Ji, De-Bin; Han, Wei; Xue, Yun; Zhang, Zhi-Jian

2014-09-01

121

Activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic salt  

SciTech Connect

Using a numerical Gibbs free-energy minimization technique, the activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic at 450 C have been calculated. Laboratory tests of an electrochemical process for separating actinide metals from rare-earth metals in LiCl/KCl solvent at 450 C provided experimental concentration and cathode potential data. The generalized expansion by Wohl was used to express the concentration dependence of the excess Gibbs free energy. The activity coefficients were expressed in terms of the Wohl volume and interaction energy parameters. The Wohl parameters for the activity coefficient expansions were obtained by minimizing the total Gibbs free energy expressed in terms of the experimental mole fractions. This thermodynamic model will be valuable for process design and scale-up calculations.

Bechtel, T.B.; Storvick, T.S. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering] [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering

1999-04-01

122

ELECTRICAL CONDUCTANCE OF THE LiCl-KCl EUTECTIC MELT CONTAINING HALIDES AND ALKALI TITANIUM FLUORIDES AS SOLUTES  

Microsoft Academic Search

The electrical conductances over the temperature range 350 to 400 of ; the LiCl-KCl eutectic melt and solutions of NaCl, LiF, NaF, KF, LiâTiF\\/sub ; 6\\/, NaâTiFâ, and KâTiFâ in this melt are reported for the ; region of dilute concentrations of the solutes. A reduced total specific ; conductance is found on the addition of fluorides to the chloride

George J. Janz; C. T. Brown; H. J. Gardner; C. Solomons

1958-01-01

123

Thermal Bleaching of F Centers and Its Correlation to Thermoluminescence in X-Ray Colored KCl Crystals  

Microsoft Academic Search

A double-Dewar vacuum system, with an effective liquid-air trap close to the crystal inside it, is described. Undisturbed thermal-bleaching curves obtained with this system do not show any restoration of F centers when one warms KCl crystals x-irradiated at liquid-air temperature. The thermal-bleaching curves obtained show steep fall-offs at certain temperatures throughout the examined temperature range of 90-600°K. The temperatures

A. A. Braner; A. Halperin

1957-01-01

124

Influence of surface charge and surface structure on the molecular and ionic sublimation of KCl single crystal  

NASA Astrophysics Data System (ADS)

A mass spectrometric method was used to study a kinetics of potassium chloride single crystal sublimation in the form of neutral molecules and positive and negative ions. In electron-impact-ionization mass spectrum K +, KCl + and K 2Cl + ions originated from KCl and K 2Cl 2 molecular precursors were detected in the temperature range 780-900 K. The curvature exposed by the temperature dependencies of ion currents, ln IiT-1/ T, was interpreted as a result of surface charge influence on the rate of sublimation. Theoretical and experimental retardation factors were analyzed for free sublimation of KCl and NaCl crystals [J.E. Lester, G.A. Somorjai, J. Chem. Phys. 49 (1968) 2940]. In thermal ionization mass spectrum K +, K 2+, K 2Cl +, K 3Cl 2+ positive ions and Cl -, Cl 2-, and KCl 2- negative ions were identified in the ranges 710-1020 K and 950-1020 K, respectively; the negative ion currents were much weaker than positive ones. During an induction period, a gradual decrease of isothermal ion currents was observed. The temperature dependence, ln I(K +)-1/ T, measured at successive stages of vaporization revealed (i) the existence of knee temperature, above and below which the ion emission is characterized by different activation energies for ion desorption, E+, (ii) the values of E+ were found to be dependent on the time elapsed from the vaporization start, i.e., on the developing surface morphology. The comparison of mass spectra of both types obtained in this work with those measured under equilibrium conditions showed the similarity of the electron-impact-ionization mass spectra and the significant difference between the thermal ionization ones. All the results are discussed in light of terrace-ledge-kink model of vaporization and surface charge concept that are a corollary of defect theory.

Butman, M. F.; Smirnov, A. A.; Kudin, L. S.

1998-04-01

125

An optimal method for phosphorylation of rare earth chlorides in LiCl-KCl eutectic based waste salt  

NASA Astrophysics Data System (ADS)

A study on an optimal method for the phosphorylation of rare earth chlorides in LiCl-KCl eutectic waste salt generated the pyrochemical process of spent nuclear fuel was performed. A reactor with a pitched four blade impeller was designed to create a homogeneous mixing zone in LiCl-KCl eutectic salt. A phosphorylation test of NdCl3 in the salt was carried out by changing the operation conditions (operation temperature, stirring rate, agent injection amount). Based on the results of the test, a proper operation condition (450 °C, 300 rpm, 1 eq. of phosphorylation agent) for over a 0.99 conversion ratio of NdCl3 to NdPO4 was determined. Under this condition, multi-component rare earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Y) chlorides were effectively converted into phosphate forms. It was confirmed that the existing regeneration process of LiCl-KCl eutectic waste salt can be greatly improved and simplified through these phosphorylation test results.

Eun, H. C.; Kim, J. H.; Cho, Y. Z.; Choi, J. H.; Lee, T. K.; Park, H. S.; Park, G. I.

2013-11-01

126

Diffusional creep of multicomponent systems. Progress report, February 1, 1980-January 31, 1981. [Dislocation-crack interactions; photoplastic and electroplastic effects in KCl  

SciTech Connect

Topics for which significant results are reported include dislocation-crack interactions, impression creep of Al polycrystals, and photoplastic and electroplastic effects in additively colored KCl. 9 figures. (DLC)

Li, J.C.M.

1981-01-01

127

Investigation of a LiCl-KCl-UCl3 system using a combination of X-ray diffraction and differential thermal analyses  

NASA Astrophysics Data System (ADS)

Electrorefining is one of the main steps in pyroreprocessing where spent nuclear fuels are recycled. Electrorefining is conducted in a molten salt of a LiCl-KCl eutectic (59:41 mol%) containing actinide chlorides (AnCl3) at 773 K. In order to operate and maintain the electrorefiner, it is necessary to accumulate fundamental data on the LiCl-KCl-AnCl3 salt, such as its melting point. In this study, based on X-ray diffraction and differential thermal analyses, partial phase diagrams of (LiCl-KCl)eut.-UCl3 pseudo-binary and LiCl-KCl-UCl3 systems, in which the UCl3 concentration was up to 20 mol%, were developed.

Nakayoshi, Akira; Kitawaki, Shinichi; Fukushima, Mineo; Murakami, Tuyoshi; Kurata, Masaki

2013-10-01

128

The effect of substitution of NaCl with KCl on chemical composition and functional properties of low-moisture Mozzarella cheese.  

PubMed

The effect of NaCl substitution with KCl on chemical composition, organic acids profile, soluble calcium, and functionality of low-moisture Mozzarella cheese (LMMC) was investigated. Functionality (meltability and browning), organic acids profile, and chemical composition were determined. Chemical composition showed no significant difference between experimental cheeses at same storage period, and same salt treatment. Meltability of LMMC salted with 3NaCl:1KCl, 1NaCl:1KCl, and 1NaCl:3KCl was higher compared with only NaCl (control). The amount of soluble Ca and P increased significantly during storage, with no significant difference between salt treatments. Organic acids profile did not differ between salt treatments at the same storage time. PMID:21787912

Ayyash, M M; Shah, N P

2011-08-01

129

The phase diagrams and Pitzer model representations for the system KCl + MgCl2 + H2O at 50 and 75°C  

NASA Astrophysics Data System (ADS)

The solubilities in the KCl-MgCl2-H2O system were determined at 50 and 75°C and the phase diagrams and the diagram of refractive index vs composition were plotted. Two invariant point, three univariant curves, and three crystallization zones, corresponding to potassium chloride, hexahydrate (MgCl2 · 6H2O) and double salt (KCl · MgCl2 · 6H2O) showed up in the phase diagrams of the ternary system, The mixing parameters ?K, Ca and ?K, Ca, Cl and equilibrium constant K sp were evaluated in KCl-MgCl2-H2O system by least-squares optimization procedure, in which the single-salt Pitzer parameters of KCl and MgCl2 ?(0), ?(1), ?(2), and C ? were directly calculated from the literature. The results obtained were in good agreement with the experimental data.

Yang, Ji-min; Peng, Jing; Duan, Yu-xia; Tian, Chong; Ping, Mei

2012-12-01

130

Resonant Raman scattering and dynamics of the FA(Li+) modes in KCl  

NASA Astrophysics Data System (ADS)

By means of the behavior-type method, the polarized resonant Raman intensities of the three FA(Li+) modes in KCl are analyzed, taking into account the optically induced reorientation of the defect. The FA( 7Li+) center is known to possess two high-frequency Raman-active vibrations, at 216 and at 266 cm-1, which exhibit a regular Li+ isotope shift and a low-frequency resonance at 47 cm-1, which shows a small and anomalous isotope effect. The investigation of their polarized Raman data necessitated an extension of the behavior-type method to the case of resonant scattering. In spite of reorientation effects the Raman scattering excited at the wavelengths of the FA1 or FA2 band is found to be dominated by the resonant contribution of the defects which can still absorb the incident light. From the analysis of the polarized Raman intensities of the 216-cm-1 mode the defect is shown to have only a mirror-plane symmetry, which independently demonstrates the off-axis position of the Li+ ion in FA(Li+). This deviation from C4v[001] symmetry is not observed in the data for the 47- and the 266-cm-1 modes, but within the C1h symmetry group all the modes belong to the representation A', i.e., they are even under reflection. The polarized Raman study, together with the isotope shifts of the Raman modes and considerations of the normal modes of the defect, permits a more detailed description of the dynamics of the FA(Li+) center: The 266- and the 216-cm-1 vibrations strongly involve the Li+-ion motion within the mirror plane, essentially parallel and perpendicular to the defect axis, respectively. The low-frequency mode at 47 cm-1 is an activated band mode in which the Li+ ion hardly participates, similar to the 43-cm-1 mode of the naked Li+ impurity.

Leblans, M.; Joosen, W.; Goovaerts, E.; Schoemaker, D.

1987-02-01

131

Current view on the functional regulation of the neuronal K+-Cl? cotransporter KCC2  

PubMed Central

In the mammalian central nervous system (CNS), the inhibitory strength of chloride (Cl?)-permeable GABAA and glycine receptors (GABAAR and GlyR) depends on the intracellular Cl? concentration ([Cl?]i). Lowering [Cl?]i enhances inhibition, whereas raising [Cl?]i facilitates neuronal activity. A neuron's basal level of [Cl?]i, as well as its Cl? extrusion capacity, is critically dependent on the activity of the electroneutral K+-Cl? cotransporter KCC2, a member of the SLC12 cation-Cl? cotransporter (CCC) family. KCC2 deficiency compromises neuronal migration, formation and the maturation of GABAergic and glutamatergic synaptic connections, and results in network hyperexcitability and seizure activity. Several neurological disorders including multiple epilepsy subtypes, neuropathic pain, and schizophrenia, as well as various insults such as trauma and ischemia, are associated with significant decreases in the Cl? extrusion capacity of KCC2 that result in increases of [Cl?]i and the subsequent hyperexcitability of neuronal networks. Accordingly, identifying the key upstream molecular mediators governing the functional regulation of KCC2, and modifying these signaling pathways with small molecules, might constitute a novel neurotherapeutic strategy for multiple diseases. Here, we discuss recent advances in the understanding of the mechanisms regulating KCC2 activity, and of the role these mechanisms play in neuronal Cl? homeostasis and GABAergic neurotransmission. As KCC2 mediates electroneutral transport, the experimental recording of its activity constitutes an important research challenge; we therefore also, provide an overview of the different methodological approaches utilized to monitor function of KCC2 in both physiological and pathological conditions. PMID:24567703

Medina, Igor; Friedel, Perrine; Rivera, Claudio; Kahle, Kristopher T.; Kourdougli, Nazim; Uvarov, Pavel; Pellegrino, Christophe

2014-01-01

132

Measurements and Analysis of Oxygen Bubble Distributions in LiCl-KCl Molten Salt  

SciTech Connect

Transparent system experimental studies have been performed to provide measurement and analysis of oxygen bubble distributions and mass transfer coefficients at different sparging rates ranging from 0.05 to 0.20 L/min in LiCl-KCl molten salt at 500 degrees C using a high-speed digital camera and an oxygen sensor. The results reveal that bubble sizes and rise velocities increased with an increase in oxygen sparging rate. The bubbles observed were ellipsoidal in shape, and an equivalent diameter based on the ellipsoid volume was calculated. The average equivalent bubble diameters at 500 degrees C and these oxygen sparging rates range from 2.63 to 4.07 mm. Results show that the bubble equivalent diameters at each respective sparging rate are normally distributed. A Fanning friction factor correlation was produced to predict a bubble’s rise velocity based on its equivalent diameter. The oxygen mass transfer coefficients for four sparging rates were calculated using the oxygenation model. These calculated values were within the order of magnitude of 10-2 cm/sec and followed a decreasing trend corresponding to an increasing bubble size and sparging rate. The diffusivities were calculated based on two different types of mechanisms, one based on physics of the bubbles and the other on systematic properties. The results reveal that diffusivity values calculated from bubble physics are 1.65 to 8.40 x 10-5 cm2/sec, which are within the range suggested by literature for gases in liquids of a similar viscosity.

Ryan W. Bezzant; Supathorn Phongikaroon; Michael F. Simpson

2013-03-01

133

Calcite precipitation from CO2 H2O Ca(OH)2 slurry under high pressure of CO2  

Microsoft Academic Search

The formation of solid calcium carbonate (CaCO3) from aqueous solutions or slurries containing calcium and carbon dioxide (CO2) is a complex process of considerable importance in the ecological, geochemical and biological areas. Moreover, the demand for powdered CaCO3 has recently increased considerably in various fields of industry. The aim of this study was therefore to synthesize fine particles of calcite

G. Montes-Hernandez; F. Renard; N. Geoffroy; L. Charlet; J. Pironon

2007-01-01

134

Effect of storage conditions on handling and SO2 reactivity of CA(OH)2-based sorbents  

Microsoft Academic Search

The article gives results of an investigation of the effect of relative humidity (RH), time, and aeration during calcium hydroxide--Ca(OH)2--storage for its effect on sorbent handling and reactivity with sulfur dioxide (SO2). Investigated was the effect of sorbent storage conditions of time (1-24 hr), RH (zero-90%), silo wall material, and aeration on handling properties of flowability and floodability and their

W. Jozewicz; B. K. Gullett

1991-01-01

135

Purification of used eutectic (LiCl-KCl) salt electrolyte from pyroprocessing  

NASA Astrophysics Data System (ADS)

The separation characteristics of surrogate rare-earth fission products in a eutectic (LiCl-KCl) molten salt were investigated. This system is based on the eutectic salt used for the pyroprocessing treatment of used nuclear fuel (UNF). The investigation was performed using an integrated rare-earth separation apparatus comprising a precipitation reactor, a solid detachment device, and a layer separation device. To separate rare-earth fission products, a phosphate precipitation method using both Li3PO4 and K3PO4 as a precipitant was performed. The use of an equivalent phosphate precipitant composed of 0.408 molar ratio-K3PO4 and 0.592 molar ratio-Li3PO4 can preserve the original eutectic ratio, LiCl-0.592 molar ratio (or 45.2 wt%), as well as provide a high separation efficiency of over 99.5% under conditions of 550 °C and Ar sparging when using La, Nd, Ce, and Pr chlorides. The mixture of La, Nd, Ce, and Pr phosphate had a typical monoclinic (or monazite) structure, which has been proposed as a reliable host matrix for the permanent disposal of a high-level waste form. To maximize the reusability of purified eutectic waste salt after rare-earth separation, the successive rare-earth separation process, which uses both phosphate precipitation and an oxygen sparging method, were introduced and tested with eight rare-earth (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) chlorides. In the successive rare-earth separation process, the phosphate reaction was terminated within 1 h at 550 °C, and a 4-8 h oxygen sparging time were required to obtain over a 99% separation efficiency at 700-750 °C. The mixture of rare-earth precipitates separated by the successive rare-earth separation process was found to be phosphate, oxychloride, and oxide. Through the successive rare-earth separation process, the eutectic ratio of purified salt maintained its original value, and impurity content including the residual precipitant of purified salt can be minimized.

Cho, Yung-Zun; Lee, Tae-Kyo; Eun, Hee-Chul; Choi, Jung-Hoon; Kim, In-Tae; Park, Geun-Il

2013-06-01

136

EXPLORING IO'S ATMOSPHERIC COMPOSITION WITH APEX: FIRST MEASUREMENT OF {sup 34}SO{sub 2} AND TENTATIVE DETECTION OF KCl  

SciTech Connect

The composition of Io's tenuous atmosphere is poorly constrained. Only the major species SO{sub 2} and a handful of minor species have been positively identified, but a variety of other molecular species should be present, based on thermochemical equilibrium models of volcanic gas chemistry and the composition of Io's environment. This paper focuses on the spectral search for expected yet undetected molecular species (KCl, SiO, S{sub 2}O) and isotopes ({sup 34}SO{sub 2}). We analyze a disk-averaged spectrum of a potentially line-rich spectral window around 345 GHz, obtained in 2010 at the APEX 12 m antenna. Using different models assuming either extended atmospheric distributions or a purely volcanically sustained atmosphere, we tentatively measure the KCl relative abundance with respect to SO{sub 2} and derive a range of 4 × 10{sup –4}-8 × 10{sup –3}. We do not detect SiO or S{sub 2}O and present new upper limits on their abundances. We also present the first measurement of the {sup 34}S/{sup 32}S isotopic ratio in gas phase on Io, which appears to be twice as high as the Earth and interstellar medium reference values. Strong lines of SO{sub 2} and SO are also analyzed to check for longitudinal variations of column density and relative abundance. Our models show that, based on their predicted relative abundance with respect to SO{sub 2} in volcanic plumes, both the tentative KCl detection and SiO upper limit are compatible with a purely volcanic origin for these species.

Moullet, A. [National Radio Astronomy Observatory, Charlottesville, VA-22902 (United States); Lellouch, E.; Moreno, R. [LESIA-Observatoire de Paris, 5 place J. Janssen, F-92195 Meudon CEDEX (France); Gurwell, M. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA-02138 (United States); Black, J. H [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Butler, B. [National Radio Astronomy Observatory, Socorro, NM-87801 (United States)

2013-10-10

137

Study on a regeneration process of LiCl-KCl eutectic based waste salt generated from the pyrochemical process  

SciTech Connect

A regeneration process of LiCl-KCl eutectic waste salt generated from the pyrochemical process of spent nuclear fuel has been studied. This regeneration process is composed of a chemical conversion process and a vacuum distillation process. Through the regeneration process, a high efficiency of renewable salt recovery can be obtained from the waste salt and rare earth nuclides in the waste salt can be separated as oxide or phosphate forms. Thus, the regeneration process can contribute greatly to a reduction of the waste volume and a creation of durable final waste forms. (authors)

Eun, H.C.; Cho, Y.Z.; Choi, J.H.; Kim, J.H.; Lee, T.K.; Park, H.S.; Kim, I.T.; Park, G.I. [Nuclear Fuel Cycle Waste Treatment Research Division, Korea Atomic Energy Research Institute, 989-111 Daedeok-Daero, Yuseong-Gu, Daejeon 3054-353 (Korea, Republic of)

2013-07-01

138

Electroconductivity of molten mixtures of LiCl-KCl eutectics with chlorides of rare-earth elements  

NASA Astrophysics Data System (ADS)

The temperature dependences of the specific and molar electroconductivities of LiCl-KCl-LnCl3 (Ln-La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb) molten mixtures were studied. It was shown that the isotherms (1070 K) of molar electroconductivity (?) for most of the studied saline systems have an S-shaped form. The observed patterns of ? isotherms and their dependence on the ratio of components in the saline mixtures under investigation are explained in the context of complex structure of ionic melts.

Kovalevskii, A. V.; Shishalov, V. I.

2011-01-01

139

Transport of ions across bipolar membranes. 1. Theoretical and experimental examination of the membrane potential of KCl solutions  

SciTech Connect

A calculation method was derived for ionic transport across a bipolar membrane in dialysis systems of mixed salt solutions containing multivalent ions. The calculation of the total membrane potential in the solutions containing KCl alone by this method shows that the potential-salt concentration curve depends both on the direction of the arrangement of the membrane charged layers to the concentration gradient of the salt solutions and on the ratio of the charge densities of the two charged layers. The simulations based on experimentally determined parameters agree with the potential measurements for bipolar membranes produced so that the transport properties depend mainly on their charges. 40 refs., 4 figs., 1 tab.

Higa, Mitsuru; Kira, Akira [Inst. of Physical and Chemical Research (RIKEN), Saitama (Japan)

1995-04-06

140

Electrochemistry and Spectroelectrochemistry of Europium(III) chloride in 3 LiCl – 2KCl from 643 to 1123 K  

SciTech Connect

The electrochemical and spectroelectrochemical behavior of Europium(III) chloride in a molten salt eutectic, 3 LiCl – 2 KCl, over a temperature range of 643 – 1123 K using differential pulse voltammetry, cyclic voltammetry, potential step chronoabsorptometry, and thin-layer spectroelectrochemistry is reported. The electrochemical reaction was determined to be the one electron reduction of Eu3+ to Eu2+ at all temperatures. The redox potential of Eu3+/2+ shifts to more positive potentials and the diffusion coefficient for Eu3+ increases as temperature increases. The results for the number of electrons transferred, redox potential and diffusion coefficient are in good agreement between the electrochemical and spectroelectrochemical techniques.

Schroll, Cynthia A.; Chatterjee, Sayandev; Levitskaia, Tatiana G.; Heineman, William R.; Bryan, Samuel A.

2013-09-09

141

Plant growth and responses of antioxidants of Chenopodium album to long-term NaCl and KCl stress  

Microsoft Academic Search

The effects of long-term NaCl and KCl treatment on plant growth and antioxidative responses were investigated in Chenopodium album, a salt-resistant species widely distributed in semi-arid and light-saline areas of Xinjiang, China. Growth parameters [plant\\u000a height, branch number, leaf morphology and chlorophyll (Chl) content], the level of oxidative stress [superoxide anion radical\\u000a (O2\\u000a ?), hydrogen peroxide (H2O2) and malondialdehyde (MDA)

Shixiang Yao; Shasha Chen; Dongsheng Xu; Haiyan Lan

2010-01-01

142

E.S.R. studies of electron irradiated K3Ir(CN)6 in KCl single crystals  

NASA Astrophysics Data System (ADS)

E.S.R. studies of KCl single crystals doped with small amounts of K3Ir(CN)6 and submitted to a prolonged 2 MeV electron irradiation at room temperature reveal the presence of the species [Ir(CN)5Cl]4- and [Ir(CN)4Cl2]4-. Ligand spin densities and ligand field parameters are calculated from the experimental hyperfine and superhyperfine interactions and compared with previous data on the species [Ir(CN)5]4-.

Vugman, N. V.; Pinhal, N. M.

143

Effect of KCl on melting of the Mg2SiO4-MgSiO3-H2O system at 5 GPa  

NASA Astrophysics Data System (ADS)

Chlorine has been found as a major constituent of fluid inclusions in fibrous diamonds (Navon et al., 1988) and has been interpreted to associate with K to form a KCl-bearing brine (e.g., Klein-BenDavid et al., 2006). To examine the effect of such a KCl-bearing brine on the melting behavior of the Earth’s mantle, we conducted experiments in the Mg2SiO4-MgSiO3-H2O and Mg2SiO4-MgSiO3-KCl-H2O systems at 5 GPa and 1100-1700°C. In the Mg2SiO4-MgSiO3-H2O system, the temperature of the solidus is ~1230°C, and both forsterite and enstatite coexist with the liquid under supersolidus conditions. In the Mg2SiO4-MgSiO3-KCl-H2O systems with molar Cl/(Cl+H2O) ratios of 0.2, 0.4 and 0.6, the temperatures of the solidus are ~1430°C, ~1530°C and ~1580°C, respectively, and only forsterite coexists with liquid under supersolidus conditions. The increase in the temperature of the solidus demonstrates the significant effect of KCl on elevating the solidus of the Mg2SiO4-MgSiO3-H2O system by reducing the activity of H2O in the fluid. If KCl is present in the Earth’s mantle, it will prevent melting at the H2O-saturated solidus, and the KCl-bearing brine will be a robust agent for mantle metasomatism at temperatures greater than that of the H2O-saturated solidus. The change in the melting residues indicates that the incongruent melting of enstatite (enstatite = forsterite + silica-rich melt) could happen at pressures over 5 GPa in KCl-bearing systems, which needs to be verified by experiments on the MgSiO3-KCl-H2O system in future work. Klein-BenDavid, O., Richard, W. and Navon, O., 2006, TEM imaging and analysis of microinclusions in diamonds; a close look at diamond-growing fluids: American Mineralogist, v. 91, p. 353-365. Navon, O., Hutcheon, I.D., Rossman, G.R. and Wasserburg, G.J., 1988, Mantle-derived fluids in diamond micro-inclusions: Nature, v. 335, p. 784-789.

Chu, L.; Luth, R. W.; Enggist, A.

2009-12-01

144

Phase equilibria in the system H{sub 2}O-NaCl-KCl-MgCl{sub 2} relevant to salt cake processing  

SciTech Connect

One waste product in recycling of Al is salt cake, a mixture of Al, salts, and residue oxides. Several methods have been proposed to recycle salt cake, one involving high-temperature leaching of salts from the salt cake. The salt composition can be approximated as a mixture predominantly of NaCl and KCl salts, with lesser amounts of Mg chloride. In order to better assess the feasibility of recycling salt cake, an experimental study was conducted of phase equilibria in the system H{sub 2}O-NaCl-KCl-MgCl{sub 2} at pressure (P), temperature (T), and composition conditions appropriate for high- temperature salt cake recycling. These experiments were designed to evaluate the effect of small amounts (2-10 wt%) of MgCl{sub 2} on solubilities of halite (NaCl) and sylvite (KCl) in saturated solutions (30-50 wt% NaCl+KCl; NaCl:KCl = 1:1 and 3:1) at elevated P and T.

Bodnar, R.J.; Vityk, M.O. [Virginia Polytechnic Inst., Blacksburg, VA (United States)] [Virginia Polytechnic Inst., Blacksburg, VA (United States); Hryn, J.N. [Argonne National Lab., IL (United States)] [Argonne National Lab., IL (United States); Mavrogenes, J. [Australian National Univ., Canberra, ACT (Australia)] [Australian National Univ., Canberra, ACT (Australia)

1997-02-01

145

Phase relations in the system NaCl-KCl-H2O: V. Thermodynamic-PTX analysis of solid-liquid equilibria at high temperatures and pressures  

USGS Publications Warehouse

The Gibbs energies of mixing for NaCl-KCl binary solids and liquids and solid-saturated NaCl-KCl-H2O ternary liquids were modeled using asymmetric Margules treatments. The coefficients of the expressions were calibrated using an extensive array of binary solvus and solidus data, and both binary and ternary liquidus data. Over the PTX range considered, the system exhibits complete liquid miscibility among all three components and extensive solid solution along the anhydrous binary. Solid-liquid and solid-solid phase equilibria were calculated by using the resulting equations and invoking the equality of chemical potentials of NaCl and KCl between appropriate phases at equilibrium. The equations reproduce the ternary liquidus and predict activity coefficients for NaCl and KCl components in the aqueous liquid under solid-saturation conditions between 673 and 1200 K from vapor saturation up to 5 kbar. In the NaCl-KCl anhydrous binary system, the equations describe phase equilibria and predict activity coefficients of the salt components for all stable compositions of solid and liquid phases between room temperature and 1200 K and from 1 bar to 5 kbar. ?? 1992.

Sterner, S.M.; Chou, I.-Ming; Downs, R.T.; Pitzer, K.S.

1992-01-01

146

Evaluation of the KCl Denuder Method for Gaseous Oxidized Mercury using HgBr2 at an In-Service AMNet Site  

NASA Astrophysics Data System (ADS)

During the summer of 2013, we examined the performance of KCl-coated denuders for measuring gaseous oxidized mercury (GOM) by calibrating with a known source of GOM (i.e., HgBr2) at the North Birmingham SouthEastern Aerosol Research and Characterization (SEARCH) site. We found that KCl-coated denuders have near 95% collection efficiency for HgBr2 in zero air (i.e., air scrubbed of mercury and ozone). However, in ambient air, the efficiency of KCl-coated denuders in capturing HgBr2 dropped to 20-54%. We also found that absolute humidity and ozone each demonstrate a significant inverse correlation with HgBr2 recovery in ambient air. Subsequent laboratory tests with HgBr2 and the KCl-coated denuder show that ozone and absolute humidity cause the release of gaseous elemental Hg from the denuder and thus appear to explain the low recovery in ambient air. Based on these findings, we infer that the KCl denuder method underestimates atmospheric GOM concentrations. A calibration system is needed to accurately measure GOM. The system described in this paper for HgBr2 could be implemented with existing mercury speciation instrumentation and this would improve our knowledge of the response to one potentially important GOM compound.

McClure, Crystal

147

Influence of partial replacement of NaCl with KCl on profiles of volatile compounds in dry-cured bacon during processing.  

PubMed

This study investigated the influence of partial substitution of NaCl with KCl on the formation of volatile compounds in bacons during processing using a purge and trap dynamic headspace GC/MS system. Three substitutions were 0% KCl (I), 40% KCl (II), and 70% KCl (III). The profiles of the volatile compounds significantly changed during processing, particularly during the drying/ripening. At the end of process, the bacons from substitution III formed significantly higher levels of lipid-derived volatiles, such as straight chain aldehydes, hydrocarbons than bacons from substitution I and II, whereas the latter formed higher levels of volatiles from amino acid degradation such as 3-methylbutanal. There were very few differences in volatile formation between 0% and 40% KCl application. These results suggest that K(+) substitution of Na(+) by more than 40% may significantly change profiles of volatiles in finished dry-cured bacons and therefore would result in changes in the product aroma and/or flavour. PMID:25442569

Wu, Haizhou; Zhuang, Hong; Zhang, Yingyang; Tang, Jing; Yu, Xiang; Long, Men; Wang, Jiamei; Zhang, Jianhao

2015-04-01

148

A Density Model for Multicomponent Liquids Based on the Modified Quasichemical Model: Application to the NaCl-KCl-MgCl2-CaCl2 System  

NASA Astrophysics Data System (ADS)

A theoretical model based on the modified quasichemical model is presented for the density of multicomponent inorganic liquids such as molten salts. By introducing in the Gibbs energy of the liquid phase temperature-dependent molar volume expressions for the pure components and pressure-dependent excess parameters for the binary (and, if necessary, higher-order) interactions, it is possible to reproduce and eventually predict the molar volume and the density of the multicomponent liquid phase using standard interpolation methods. The model is applied to the NaCl-KCl-MgCl2-CaCl2 liquid solutions. No ternary pressure-dependent model parameters were required; the binary pressure-dependent parameters suffice to reproduce satisfactorily the experimental density data available for the NaCl-KCl-MgCl2, NaCl-KCl-CaCl2, NaCl-MgCl2-CaCl2, KCl-MgCl2-CaCl2, and NaCl-KCl-MgCl2-CaCl2 liquids. This is the first of two articles on the density model. In a subsequent article, the model is applied to the NaF-AlF3-CaF2-Al2O3 base electrolyte used for the electroreduction of alumina in Hall-Héroult cells.

Robelin, Christian; Chartrand, Patrice; Eriksson, Gunnar

2007-12-01

149

K-Cl cotransporter KCC2-a moonlighting protein in excitatory and inhibitory synapse development and function.  

PubMed

The K-Cl cotransporter KCC2 has two entirely independent biological actions as either an ion transporter or a structural protein orchestrating the organization of the cytoskeleton in neuronal structures. The K-Cl cotransport by KCC2 is central for hyperpolarizing inhibitory signaling, which is based on chloride currents mediated by ?-aminobutyric acid (GABA)- or glycine-gated receptor channels. In contrast, the structural role of KCC2 seems to be crucially involved in the maturation and regulation of excitatory glutamatergic synapses. This dual role at GABAergic/glycinergic and glutamatergic synapses makes KCC2 a key molecule in the regulation of inhibitory and excitatory signaling. Therefore, KCC2 is most likely involved in the synchronization of the two types of activity during network formation in the immature system and a similar synchronizing role might also be important under physiological and pathological conditions in mature neuronal networks. In this review, we explore new findings on the regulation of KCC2 by protease-mediated cleavage and on the structural role of KCC2 in spine morphogenesis and glutamate receptor clustering. We then discuss the implications of the putative interaction between the independent functions of the transporter and overlapping regulatory mechanisms in a neurophysiological context. In addition, we look at the multifunctional properties of KCC2 in the light of evolution and propose that KCC2 belongs to the group of moonlighting (multifunctional) proteins. PMID:24909111

Blaesse, Peter; Schmidt, Tobias

2015-04-01

150

In situ STM studies of electrochemically polished Cd(0001) electrode in aqueous electrolyte solutions  

NASA Astrophysics Data System (ADS)

The in situ STM studies of electrochemically polished Cd(0001) electrode in the H3PO4 aqueous solution have been performed under negative electrode potentials from - 1.4 to - 0.9 V (versus Ag|AgCl in sat. KCl aqueous solution) in the 0.1 M Na2SO4 + 1 × 10- 5 M H2SO4 aqueous solution. The atomic resolution parameters of Cd(0001) surface have been calculated. The in situ STM data show that there are no surface reconstruction processes and the surface structure of electrochemically polished Cd(0001) is stable within the potential region investigated.

Pikma, P.; Grozovski, V.; Kasuk, H.; Lust, E.

2014-10-01

151

Measurement and thermodynamic model study on equilibrium solubility in the ternary system KCl-KBr-H2O at 323.15 K  

NASA Astrophysics Data System (ADS)

The solubilities and the refractive indices of the KCl-KBr-H2O system at 323.15 K were studied with the isothermal dissolution method. The phase diagram and refractive index diagram were plotted for this system at 323.15 K. There is only one crystallization field of the solid solution K(Cl, Br). The system belongs to the solid solution type. The refractive indices of the equilibrium solution varies regularly with w(KCl) increasing. The calculated refractive index data are in good agreement with the experimental data. The parameter ?K, Cl, Br at 323.15 K was fitted using the measured solubility data in this study. The equilibrium constant equation for the equilibrium solids at 323.15 K were obtained using the different Pitzer parameters from the literature or this work with a method using the activity product constant. The calculated solubilities agree well with experimental values.

Meng, Ling-Zong; Li, Dan; Ma, Cun-Yun; Liu, Kai-Xuan

2014-12-01

152

Effect of KCl on melting in the Mg2SiO4-MgSiO3-H2O system at 5 GPa  

NASA Astrophysics Data System (ADS)

To examine the effect of KCl-bearing fluids on the melting behavior of the Earth's mantle, we conducted experiments in the Mg2SiO4-MgSiO3-H2O and Mg2SiO4-MgSiO3-KCl-H2O systems at 5 GPa. In the Mg2SiO4-MgSiO3-H2O system, the temperature of the fluid-saturated solidus is bracketed between 1,200-1,250°C, and both forsterite and enstatite coexist with the liquid under supersolidus conditions. In the Mg2SiO4-MgSiO3-KCl-H2O systems with molar Cl/(Cl + H2O) ratios of 0.2, 0.4, and 0.6, the temperatures of the fluid-saturated solidus are bracketed between 1,400-1,450°C, 1,550-1,600°C, and 1,600-1,650°C, respectively, and only forsterite coexists with liquid under supersolidus conditions. This increase in the temperature of the solidus demonstrates the significant effect of KCl on reducing the activity of H2O in the fluid in the Mg2SiO4-MgSiO3-H2O system. The change in the melting residues indicates that the incongruent melting of enstatite (enstatite = forsterite + silica-rich melt) could extend to pressures above 5 GPa in KCl-bearing systems, in contrast to the behavior in the KCl-free system.

Chu, Linglin; Enggist, Andreas; Luth, Robert W.

2011-09-01

153

Volatile products from the interaction of KCl/g/ with Cr2O3 and LaCrO3 in oxidizing environments. [gas turbine engines  

NASA Technical Reports Server (NTRS)

Based on cooled target collection methods and high pressure mass spectrometer sampling, oxidative vaporization rates and emanating volatile products were evaluated for interactions of KCl(g) with Cr2O3 and LaCrO3 in oxidizing environments. It was found that: (1) increased rates of oxidative vaporization upon exposure to the reactants are exhibited by chromia and fresh lanthanum chromite samples, and (2) these increased rates result from the heterogeneous formation of complex molecules such as KCl sub 1,2,3CrO3 and KOH sub 1,2CrO3. No increased rates were observed for lanthanum chromite subjected to prolonged oxidative vaporization.

Kohl, F. J.; Miller, R. A.; Stearns, C. A.; Fryburg, G. C.; Dillard, J. G.

1977-01-01

154

Time-resolved laser-induced fluorescence spectroscopy of Nd 3+ in molten LiCl-KCl eutectic  

NASA Astrophysics Data System (ADS)

The characteristics of the laser-induced fluorescence of Nd3+ in LiCl-KCl eutectic in the wavelength region of 360-900 nm were investigated for information concerning the chemical speciation of Nd-chloride complexes. When pumped at either 355 or 532 nm, Nd3+ in molten salt emits visible and near-IR fluorescence. The fluorescence peaks at 750 nm (4F7/2 + 4S3/2 ? 4I9/2) and 810 nm (4F5/2 + 2H9/2 ? 4I9/2) were particularly prominent at temperatures above the melting point. The fluorescence decay of these transition lines showed a bi-exponential behaviour of the fluorescence lifetime. These results provide evidence that two different chemical species of Nd3+ coexist in this system.

Jung, E. C.; Bae, S.-E.; Park, Y. J.; Song, K.

2011-11-01

155

Determination of uranium and rare-earth metals separation coefficients in LiCl KCl melt by electrochemical transient techniques  

NASA Astrophysics Data System (ADS)

The main step in the pyrometallurgical process of spent nuclear fuel recycling is a molten salt electrorefining. The knowledge of separation coefficients of actinides (U, Np, Pu and Am) and rare-earth metals (Y, La, Ce, Nd and Gd) is very important for this step. Usually the separation coefficients are evaluated from the formal standard potentials of metals in melts containing their own ions, values obtained by potentiometric method. Electrochemical experiments were carried out at 723-823 K in order to estimate separation coefficients in LiCl-KCl eutectic melt containing uranium and lanthanum trichlorides. It was shown that for the calculation of uranium and lanthanum separation coefficients it is necessary to determine the voltammetric peak potentials of U(III) and La(III), their concentration in the melt and the kinetic parameters relating to U(III) discharge such as transfer and diffusion coefficients, and standard rate constants of charge transfer.

Kuznetsov, S. A.; Hayashi, H.; Minato, K.; Gaune-Escard, M.

2005-09-01

156

Preparation of Mo nanopowders through electroreduction of solid MoS2 in molten KCl-NaCl.  

PubMed

Electrolysis of MoS2 to produce Mo nanopowders and elemental sulfur has been studied in an equimolar mixture of NaCl and KCl at 700 °C. The reduction mechanism was investigated by cyclic voltammetry (CV), potentiostatic and constant voltage electrolysis together with spectroscopic and scanning electron microscopic analyses. The reduction pathway was identified to be MoS2 ? LxMoS2 (x ? 1, L = Na or K) ? L3Mo6S8 and LMo3S3 ? Mo, and the last step to format metallic Mo was found to be relatively slow in kinetics. Electrolysis at a cell voltage of 2.7 V has led to a rapid reduction of MoS2 to nodular Mo nanoparticles (50-100 nm), with the current efficiency and energy consumption being about 92% and 2.07 kW h kg(-1)-Mo, respectively. PMID:25105181

Gao, Haiping; Tan, Mingsheng; Rong, Liangbin; Wang, Zhiyong; Peng, Junjun; Jin, Xianbo; Chen, George Z

2014-09-28

157

Ultrafast laser-induced molecular and morphological changes during spinodal demixing of water/2-butoxyethanol/KCl  

NASA Astrophysics Data System (ADS)

We initiated morphological and molecular level changes in the spinodal decomposition (SD) of H2O/2-butoxyethanol/KCl with a pulsed ir laser. Transient Raman spectra gave us a molecular level view of the early stage of this process that could be linked to later morphological events. Chemical changes during SD, such as reorganization of H bonds and forced hydrophobic interactions, ended after 1 ?s; however, phase domains continued to grow with self-similarity after 30 ?s. The growth of the phase domains satisfied the power law L(t)˜t0.55 and was consistent with the late stage of SD. The time scale for the onset of late stage SD is many orders of magnitude faster than previously reported in ionic and nonionic conditions.

Takamizawa, Atsushi; Kajimoto, Shinji; Hobley, Jonathan; Fukumura, Hiroshi; Tran-Cong, Qui

2003-08-01

158

Zr electrorefining process for the treatment of cladding hull waste in LiCl-KCl molten salts  

SciTech Connect

Zr electrorefining for the treatment of Zircaloy-4 cladding hull waste is demonstrated in LiCl-KCl-ZrCl{sub 4} molten salts. Although a Zr oxide layer thicker than 5 ?m strongly inhibits the Zr dissolution process, pre-treatment processes increases the dissolution kinetics. For 10 g-scale experiments, the purities of the recovered Zr were 99.54 wt.% and 99.74 wt.% for fresh and oxidized cladding tubes, respectively, with no electrical contact issue. The optimal condition for Zr electrorefining has been found to improve the morphological feature of the recovered Zr, which reduces the salt incorporation by examining the effect of the process parameters such as the ZrCl{sub 4} concentration and the applied potential.

Lee, Chang Hwa; Lee, You Lee; Jeon, Min Ku; Kang, Kweon Ho; Choi, Yong Taek; Park, Geun Il [Korea Atomic Energy Research Institute - KAERI, 989-111 Daeduk-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

2013-07-01

159

Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures  

PubMed Central

Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1?:?1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used. PMID:25210645

Porcayo-Calderón, J.; Sotelo-Mazón, O.; Casales-Diaz, M.; Ascencio-Gutierrez, J. A.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

2014-01-01

160

Effect of partial NaCl substitution with KCl on the texture profile, microstructure, and sensory properties of low-moisture mozzarella cheese.  

PubMed

The effect of partial substitution of NaCl with KCl on texture profile, soluble Ca, K, Na, and P, and microstructure of low-moisture mozzarella cheese (LMMC) was investigated. LMMC batches were prepared using four combinations of NaCl and KCl salt viz., NaCl only, NaCl:KCl, 3:1, 1:1 and 1:3 (w/w); all used at of 46 g/kg curd and plasticised in 4% brine containing the above salt mixtures. Texture profile, microstructure, and percentages of soluble Ca, K, Na, and P were determined. There were no significant differences in hardness, cohesiveness, adhesiveness, and gumminess among the experimental LMMC batches. Environmental scanning electron microscopy images showed compact and homogeneous structure of LMMC at day 27 of storage; however, no significant difference was observed among the experimental LMMC batches. Hardness increased significantly in all experimental LMMC during storage. LMMC salted with NaCl/KCl mixtures had almost similar sensory properties compared with the control. There was no significant difference in creaminess, bitterness, saltiness, sour-acid, and vinegary taste among the experimental LMMC at the same storage period. PMID:22998741

Ayyash, Mutamed M; Sherkat, Frank; Shah, Nagendra P

2013-02-01

161

Effect of partial substitution of NaCl with KCl on Halloumi cheese during storage: chemical composition, lactic bacterial count, and organic acids production.  

PubMed

The effect of partial substitution of NaCl with KCl on chemical composition, lactic bacterial count, and organic acids profile of Halloumi cheese was investigated. Halloumi cheeses were made and kept in 4 different brine solutions at 18% including NaCl only (HA), 3NaCl : 1KCl (HB), 1NaCl : 1KCl (HC), and 1NaCl : 3KCl (HD) and then stored at 4 degrees C for 56 d. No significant effect was observed between control and experimental cheeses in terms of moisture, fat, protein, lactic bacterial count, and pH values at the same storage period. There was a significant difference in ash, sodium, and potassium contents among experimental cheeses at the same storage period. Ash, sodium, and potassium contents increased significantly during storage at same salt treatment. There was no significant difference in lactic and citric acid contents among experimental cheeses and that of the control. In contrary, there was a significant difference in acetic acid among experimental cheeses. A strong positive correlation was observed between ash, Na, and K contents. An inverse correlation between organic acids and both Na and K contents was also observed. PMID:20722906

Ayyash, Mutamed M; Shah, Nagendra P

2010-08-01

162

Rate of activation and deactivation of K?Cl cotransport by changes in cell volume in hemoglobin SS, CC and AA red cells  

Microsoft Academic Search

Red blood cells (RBC) of subjects homozygous for hemoglobin A (AA), C (CC) and S (SS) exhibit different cell volumes which might be related to differences in cell volume regulation. We have investigated how rapidly K:Cl cotransport is activated and deactivated to regulate the cell volume in these cells. We measured the time course of net K+ efflux after step

M. Canessa; J. R. Romero; C. Lawrence; R. L. Nagel; M. E. Fabry

1994-01-01

163

Fluorescent Spectra of Sm2+ in KCl. III. Site-Symmetry Correlation of Lines by Crystal Comparison and the Thermal Dependence of Intensities and Lifetimes  

Microsoft Academic Search

In this final paper in the series on the fluorescent spectra of Sm2+ in KCl, the authors present results of studies on the spectra of two different crystals at different temperatures, together with detailed studies in one crystal of the intensity and lifetime behavior versus temperature. Three sets of lines are found corresponding to three different site symmetries for the

R. E. Bradbury; E. Y. Wong

1971-01-01

164

Influence of the mineralogical composition on the self-potential response to1 advection of KCl concentration fronts through sand.2  

E-print Network

concentration fronts through sand.2 3 Alexis Maineult, Laurence Jouniaux and Yves Bernabé4 5 Institut de of KCl12 concentration fronts through two laboratory-scale sand-bodies with different13 mineralogical composition. In pure quartz sand, the amplitude and polarity of the SP14 signals agreed with a previously

Paris-Sud XI, Université de

165

Experimental Determination of Calcite Solubility in H2O-KCl-NaCl-LiCl Solutions at 700 °C and 8 kbar  

NASA Astrophysics Data System (ADS)

Calcium carbonate minerals are an important reservoir for subducted carbon. Their stability and solubility plays a major role in mediating the loss of carbon from subducting lithosphere, and therefore in the balance between carbon returned to the surface via arc volcanism and carbon delivered to the mantle. Relatively little oxidized carbon is liberated by mineral transformations during H2O infiltration (e.g., Connolly and Kerrick, 2001, Nature, 411, 293); however, CaCO3 dissolution in alkali-halide brines may liberate significant carbon (Newton and Manning, 2002, Am. Min., 87, 1401). We built on the work of Newton and Manning (2002) by measuring the solubility of calcite in NaCl, KCl and LiCl brines at 700°C and 8 kbar. All experiments employed hydrothermal piston-cylinder and weight-loss methods. We first established solubility as a function of salt concentration for binary LiCl-, KCl-, and NaCl-H2O solutions. In all solutions, calcite solubility increases exponentially with increasing salt mole fraction. At a given salt concentration, calcite solubility increases as the dissolved cation becomes progressively lighter; i.e., solubility increases with salt identity as KClKCl, KCl-LiCl, NaCl-LiCl). Solubilities in salt mixtures increased linearly as a function of chemical hardness, with the solubilities of CaCO3 in the mixtures being bounded by the solubilities of the end-member salts. Observations imply that calcite solubility in salt solutions are predictable using Pearson's hard-soft acid-base rules. Our results demonstrate that fluid salinity exerts a strong control on carbon transport in high-pressure metasomatic environments, such as subduction zones.

Eguchi, J.; Manning, C. E.; Li, Y.

2013-12-01

166

The role of activator concentration and precipitate formation on optical and dosimetric properties of KCl:Eu2+ storage phosphor detectors  

PubMed Central

Purpose: The activator ion (Eu2+ in KCl:Eu2+) plays an important role in the photostimulated luminescence (PSL) mechanism of storage phosphor radiation detectors. In order to design an accurate, effective, and robust detector, it is important to understand how the activator ion concentration affects the structure and, consequently, radiation detection properties of KCl:Eu2+. Methods: Potassium chloride pellets were fabricated with various amounts of europium dopant (0.01–5.0 mol.% Eu2+). Clinical radiation doses were given with a 6 MV linear accelerator. Radiation doses larger than 100 Gy were given with a 137Cs irradiator. Dose response curves, radiation hardness, and temporal signal stability were measured using a laboratory PSL readout system. The crystal structure of the material was studied using x ray diffraction and luminescence spectroscopy. Results: The most intense PSL signal was from samples with 1.0 mol.% Eu. However, samples with concentrations higher than 0.05 mol.% Eu exhibited significant degradation in PSL intensity for cumulated doses larger than 3000 Gy. Structural and luminescence spectroscopy showed clear evidence of precipitate phases within the KCl lattice, especially for high activator concentrations. Analysis of PL emission spectra showed that interactions between Eu-Vc dipoles and Eu-Vc trimers could explain trends in PSL sensitivity and radiation hardness observations. Conclusions: The concentration of the activator ion (Eu2+) significantly affects radiation detection properties of the storage phosphor KCl:Eu2+. An activator concentration between 0.01 and 0.05 mol.% Eu in KCl:Eu2+ storage phosphor detectors is recommended for linear dose response, good PSL sensitivity, predictable temporal stability, and high reusability for megavoltage radiation detection. PMID:24007173

Hansel, Rachael A.; Xiao, Zhiyan; Hu, Yanle; Green, Olga; Yang, Deshan; Harold Li, H.

2013-01-01

167

The role of activator concentration and precipitate formation on optical and dosimetric properties of KCl:Eu{sup 2+} storage phosphor detectors  

SciTech Connect

Purpose: The activator ion (Eu{sup 2+} in KCl:Eu{sup 2+}) plays an important role in the photostimulated luminescence (PSL) mechanism of storage phosphor radiation detectors. In order to design an accurate, effective, and robust detector, it is important to understand how the activator ion concentration affects the structure and, consequently, radiation detection properties of KCl:Eu{sup 2+}.Methods: Potassium chloride pellets were fabricated with various amounts of europium dopant (0.01–5.0 mol.% Eu{sup 2+}). Clinical radiation doses were given with a 6 MV linear accelerator. Radiation doses larger than 100 Gy were given with a {sup 137}Cs irradiator. Dose response curves, radiation hardness, and temporal signal stability were measured using a laboratory PSL readout system. The crystal structure of the material was studied using x ray diffraction and luminescence spectroscopy.Results: The most intense PSL signal was from samples with 1.0 mol.% Eu. However, samples with concentrations higher than 0.05 mol.% Eu exhibited significant degradation in PSL intensity for cumulated doses larger than 3000 Gy. Structural and luminescence spectroscopy showed clear evidence of precipitate phases within the KCl lattice, especially for high activator concentrations. Analysis of PL emission spectra showed that interactions between Eu-V{sub c} dipoles and Eu-V{sub c} trimers could explain trends in PSL sensitivity and radiation hardness observations.Conclusions: The concentration of the activator ion (Eu{sup 2+}) significantly affects radiation detection properties of the storage phosphor KCl:Eu{sup 2+}. An activator concentration between 0.01 and 0.05 mol.% Eu in KCl:Eu{sup 2+} storage phosphor detectors is recommended for linear dose response, good PSL sensitivity, predictable temporal stability, and high reusability for megavoltage radiation detection.

Hansel, Rachael A.; Xiao, Zhiyan; Hu, Yanle; Green, Olga; Yang, Deshan; Harold Li, H. [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)] [Department of Radiation Oncology, Washington University School of Medicine, 4921 Parkview Place, Campus Box 8224, St. Louis, Missouri 63110 (United States)

2013-09-15

168

Effects of chromated-phosphate treatment process on the green color protection of ma bamboo ( Dendrocalamus latiflorus )  

Microsoft Academic Search

Ma bamboo (Dendrocalamus latiflorus Munro) treated with chromated phosphate (CP) exhibits an excellent green color. To understand the effects of the treatment\\u000a sequence of CrO3 and H3PO4 and their interactions regarding green color protection, CrO3-H3PO4 and H3PO4-CrO3 two-step treatments plus a H3PO4-CrO3-H3PO4 three-step treatment were carried out in this study. Results revealed that the treatment sequence of CrO3 and H3PO4

Shang-Tzen Chang; Jyh-Horng Wu; Ting-Feng Yeh

2002-01-01

169

Quantitative analysis of Eu 2+ and Eu 3+ in LiCl-KCl eutectic melt by spectrophotometry and electrochemistry  

NASA Astrophysics Data System (ADS)

The redox behavior of Eu 2+ and Eu 3+ in the LiCl-KCl eutectic at 773 K was investigated. Since the equilibrium potential of the melt is very close to the redox potential of the Eu 3+|Eu 2+ couple, the Eu 2+ and Eu 3+ species coexist. Quantitative analysis of Eu 2+ and Eu 3+ was performed by spectrophotometry and by potentiometry. Under the coexistence of Eu 2+ and Eu 3+, potentiometric titration of Eu ion using a yttria-stabilized zirconia membrane electrode (YSZME) was performed by changing the concentration of O 2-. The formation of the europium oxychloride, EuOCl, was confirmed by X-ray diffraction analysis, whiles no precipitation of the oxides, EuO and Eu 2O 3, was found. The equivalent point of the EuOCl formation ( x = [O 2-] added/[Eu] total) was shifted to a smaller value from the theoretical value ( x = 1) due to the coexisting Eu 2+. The contribution of the coexisting Eu 2+ to the formation of EuOCl was estimated by using [Eu 2+]/[Eu 3+] as determined by potentiometry and this was subtracted from the titration data. The solubility product of EuOCl was determined to be p ks(EuOCl) = 7.81 ± 0.10.

Kim, Tack-Jin; Uehara, Akihiro; Nagai, Takayuki; Fujii, Toshiyuki; Yamana, Hajimu

2011-02-01

170

Effect of intracellular magnesium and oxygen tension on K+-Cl- cotransport in normal and sickle human red cells.  

PubMed

In red cells from normal individuals (HbA cells), the K+-Cl- cotransporter (KCC) is inactivated by low O2 tension whilst in those from sickle cell patients (HbS cells), it remains fully active. Changes in free intracellular [Mg2+] have been proposed as a mechanism. In HbA cells, KCC activity was stimulated by Mg2+ depletion and inhibited by Mg2+ loading but the effect of O2 was independent of Mg2+. At all [Mg2+]is, the transporter was stimulated in oxygenated cells, minimally active in deoxygenated ones. By contrast, the stimulatory effects of O2 was abolished by inhibitors of protein (de)phosphorylation. HbS cells had elevated KCC activity, which was of similar magnitude in oxygenated and deoxygenated cells, regardless of Mg2+ clamping. In deoxygenated cells, the antisickling agent dimethyl adipimidate inhibited sickling, Psickle and KCC. Results indicate a role for protein phosphorylation in O2 dependence of KCC, with different activities of the relevant enzymes in HbA and HbS cells, probably dependent on Hb. PMID:16543728

Muzyamba, Morris C; Campbell, Elaine H; Gibson, John S

2006-01-01

171

Conservative management of cervical pregnancy with intramuscular administration of methotrexate and KCl injection: Case report and review of the literature  

PubMed Central

We report the case of a cervical pregnancy successfully treated with intramuscular injection of methotrexate (MTX) and intramniotic administration of potassium chloride. A 41-year-old woman was admitted to our Department with the suspicion of ectopic pregnancy. Transvaginal ultrasound revealed empty endometrial cavity, gestational sac within the cervical canal and embryonic echo measuring crown rump length 1.5 mm. Serum beta human chorionic gonadotropine (?-HCG) was measured 28590 IU/L. No cardiac activity was detected. The diagnosis of a cervical pregnancy was made. Patient was treated with intramuscular administration of methotrexate (50 mg/m2) in combination with ultrasound-guided intramniotic injection of KCl (2 meq/mL). Gradual decrease of ?-HCG levels as well as ultrasound observation of collapsed gestational sac was observed. No curettage was necessitated. Patient was discharged on day 10th and was set in follow-up on a weekly basis. ?-HCG values were measured < 10 IU/L on 56th day after MTX administration. Intramuscular administration of MTX may be effective in treatment of cervical pregnancy without additional interventional measures. PMID:25610854

Petousis, Stamatios; Margioula-Siarkou, Chrysoula; Kalogiannidis, Ioannis; Karavas, George; Palapelas, Vasileios; Prapas, Nikolaos; Rousso, David

2015-01-01

172

Electrochemical Study on the Electrodeposition of U, Nd, Ce, La and Y on a Liquid Cadmium Cathode in a LiCl-KCl Eutectic Salt  

SciTech Connect

Electro-depositions of U, Nd, Ce, La and Y on a liquid cadmium cathode in a LiCl-KCl eutectic salt were studied by using an electrolytic cell. For the LiCl-KCl-UCl{sub 3}- NdCl{sub 3}-CeCl{sub 3}-LaCl{sub 3}-YCl{sub 3}/Cd system, cyclic voltammograms and polarization curves were measured and the electrochemical properties of the system were discussed. From the results of the electro-depositions of U and rare earth metals on the LCC, separation factors and recovery ratios of U and REs were obtained and co-electro-depositions of U and REs were investigated. (authors)

Sung Bin Park; Jong Hyeon Lee; Sung Chan Hwang; Young Ho Kang; Joon Bo Shim; Han Soo Lee; Eung Ho Kim; Seong Won Park [Korea Atomic Energy Research Institute, 1045 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

2007-07-01

173

Volatile products from the interaction of KCl(g) with Cr2O3 and LaCrO3 in oxidizing environments  

NASA Technical Reports Server (NTRS)

Cooled target collection techniques and high pressure mass spectrometric sampling were used to measure the relative rates of oxidative vaporization and to identify the volatile products emanating from samples of chromia and Mg-doped lanthanum chromite. The materials were exposed to partial pressures of KCl with and without H2O in one atmosphere of slowly flowing oxygen at elevated temperatures. Chromia and fresh samples of lanthanum chromite exhibited enhanced rates of oxidative vaporization upon exposure to these reactants. Mass spectrometric identification showed that the enhancements resulted from the heterogeneous formation of complex molecules of the type KCl sub 1,2,3 CrO3 and KOH sub l,2 CrO3. Lanthanum chromite that had undergone prolonged oxidative vaporization exhibited no enhanced oxidation upon exposure to the reactants.

Kohl, F. J.; Miller, R. A.; Stearns, C. A.; Fryburg, G. C.; Dillard, J. G.

1977-01-01

174

Electrochemical and Thermodynamic Properties of EuCl3 and EuCl2 in an Equimolar NaCl-KCl Melt  

NASA Astrophysics Data System (ADS)

The electroreduction of EuCl3 in an equimolar NaCl-KCl mixture was studied at 973 -1123 K by different electrochemical methods. This reduction of Eu(III) in NaCl-KCl melt occurs via two successive reversible steps involving transfer of one and two electrons. The diffusion coefficients of Eu(III) and Eu(II) were measured by linear sweep voltammetry and chronopotentiometry. The values found by these methods are in a good agreement. The standard rate constants for the redox reaction Eu(III) + e~ Eu(II) were calculated from cyclic voltammetry data. The sluggish kinetics of this reaction is discussed in terms of substantial rearrangement of the europium coordination sphere. Special attention was paid to the choice of working electrodes for the study of electrode reactions. The formal standard potentials E*E u (^ /Ba, E* eU (hr/eu and the formal redox potentials ^*Eu(ni)/Eu(ii) were determined from open-circuit potentiometry and linear sweep voltammetry data. The free Gibbs energy changes for the reaction EuCl3(so1) EuCl2(SOi.) + 1/2 Cl2(g.) and the equilibrium constants of the metal-salt reaction 2Eu(III) + Eu 3 Eu(II) were calculated. The thermodynamics of the formation of dilute solutions of europium di-and trichloride in an equimolar NaCl-KCl melt were determined. It was shown that electrochemical transient techniques give the possibility of the determination of the relative partial molar mixing enthalpy of europium trichloride and dichloride in NaCl-KCl melt.

Kuznetsov, S. A.; Rycerz, L.; Gaune-Escard, M.

2001-11-01

175

Thermochemical properties of lanthanides (Ln = La, Nd) and actinides (An = U, Np, Pu, Am) in the molten LiCl KCl eutectic  

NASA Astrophysics Data System (ADS)

The electrochemical reduction of actinides (U, Pu, Np and Am) and lanthanides (La and Nd) chlorides was investigated by cyclic voltammetry and chronopotentiometry at different temperatures in LiCl-KCl eutectic. The diffusion coefficients of these metallic cations were estimated as well as their apparent standard potentials. These values of potentials are compared with existing data measured also by transient electrochemical techniques or e.m.f. measurements.

Masset, Patrick; Konings, Rudy J. M.; Malmbeck, Rikard; Serp, Jérôme; Glatz, Jean-Paul

2005-09-01

176

Effect of KCl and KNO3 on Partial Molal Volumes and Partial Molal Compressibilities of Some Amino Acids at Different Temperatures  

NASA Astrophysics Data System (ADS)

Density ( ?) and ultrasonic velocity ( u) values of amino acids l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and 2M aqueous KNO3 solutions have been measured as a function of amino acid concentration at different temperatures (298.15 K, 303.15 K, 308.15 K, 313.15 K, 318.15 K, and 323.15 K). Using the ? and u data, partial molal volume ({?_v^o}) and partial molal isentropic compressibility ({?_k^o }) values have been computed. The increase in partial molal volume with temperature has been attributed to the volume expansion of hydrated zwitterions. The {?_v^o} and {?_k^o} values of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO3 solutions have been found to be larger than the corresponding values in water. The larger partial molal volumes of l-alanine, l-proline, l-valine, and l-leucine in 2M aqueous KCl and KNO3 solutions have been ascribed to the formation of ‘zwitterion-K+/Cl-/NO{3/-}’ and ‘K+/Cl-/NO{3/-}-water dipole’ aggregates in solutions. The formation of these entities in solutions causes the release of water associated with zwitterions to the bulk water. The larger partial molal compressibilities of l-alanine-/ l-proline-/ l-valine-/ l-leucine-2M aqueous KCl/KNO3 solutions than the corresponding values in water have been attributed to the formation of ‘zwitterion-ion’ and ‘ion-water dipole’ incompressible entities in solutions.

Riyazuddeen; Khan, Imran

2009-04-01

177

Functional Role of RNA Polymerase II and P70 S6 Kinase in KCl Withdrawal-induced Cerebellar Granule Neuron Apoptosis.  

PubMed

KCl withdrawal-induced apoptosis in cerebellar granule neurons is associated with aberrant cell cycle activation, and treatment with cyclin-dependent kinase (Cdk) inhibitors protects cells from undergoing apoptosis. Because the Cdk inhibitor flavopiridol is known to inhibit RNA polymerase II (Pol II)-dependent transcription elongation by inhibiting the positive transcription elongation factor b (P-TEFb, a complex of CDK9 and cyclin T), we examined whether inhibition of RNA Pol II protects neurons from apoptosis. Treatment of neurons with 5, 6-dichloro-1-?-d-ribobenzimidazole (DRB), an RNA Pol II-dependent transcription elongation inhibitor, and flavopiridol inhibited phosphorylation and activation of Pol II and protected neurons from undergoing apoptosis. In addition to Pol II, neurons subjected to KCl withdrawal showed increased phosphorylation and activation of p70 S6 kinase, which was inhibited by both DRB and flavopiridol. Immunostaining analysis of the neurons deprived of KCl showed increased nuclear levels of phospho-p70 S6 kinase, and neurons protected with DRB and flavopiridol showed accumulation of the kinase into large spliceosome assembly factor-positive speckle domains within the nuclei. The formation of these foci corresponded with cell survival, and removal of the inhibitors resulted in dispersal of the speckles into smaller foci with subsequent apoptosis induction. Because p70 S6 kinase is known to induce translation of mRNAs containing a 5'-terminal oligopyrimidine tract, our data suggest that transcription and translation of this subset of mRNAs may contribute to KCl withdrawal-induced apoptosis in neurons. PMID:25568312

Padmanabhan, Jaya; Brown, Kristy R; Padilla, Amelia; Shelanski, Michael L

2015-02-27

178

Vacuum distillation of a mixture of LiCl-KCl eutectic salts and RE oxidative precipitates and a dechlorination and oxidation of RE oxychlorides.  

PubMed

In this study, a vacuum distillation of a mixture of LiCl-KCl eutectic salt and rare-earth oxidative precipitates was performed to separate a pure LiCl-KCl eutectic salt from the mixture. Also, a dechlorination and oxidation of the rare-earth oxychlorides was carried out to stabilize a final waste form. The mixture was distilled under a range of 710-759.5Torr of a reduced pressure at a fixed heating rate of 4 degrees C/min and the LiCl-KCl eutectic salt was completely separated from the mixture. The required time for the salt distillation and the starting temperature for the salt vaporization were lowered with a reduction in the pressure. Dechlorination and oxidation of the rare-earth oxychlorides was completed at a temperature below 1300 degrees C and this was dependent on the partial pressure of O2. The rare-earth oxychlorides (NdOCl/PrOCl) were transformed to oxides (Nd2O3/PrO2) during the dechlorination and oxidation process. These results will be utilized to design a concept for a process for recycling the waste salt from an electrorefining process. PMID:18440139

Eun, Hee Chul; Yang, Hee Chul; Cho, Yung Zun; Lee, Han Soo; Kim, In Tae

2008-12-30

179

The effect of ovariectomy on depressed contractions to phenylephrine and KCl and increased relaxation to acetylcholine in isolated aortic rings of female compared to male rabbits.  

PubMed Central

1. Differences in vascular responses to phenylephrine, acetylcholine (ACh) and potassium chloride (KCl) were studied in rabbit aorta from female and male rabbits, in the absence and presence of an inhibitor of nitric oxide (NO) production, NG-nitro-L-arginine methyl ester (L-NAME, 100 microM). 2. Phenylephrine and KCl-induced contractions, were significantly reduced in amplitude (P < 0.01) in the rings from female rabbits compared to those from male rabbits. 3. ACh-induced relaxation was greater (P < 0.01) in aortic rings from females than from males. 4. Incubation of the rings with L-NAME abolished the phenylephrine-induced contraction differences between rings from male and female rabbits. 5. Ovariectomy eliminated the differences in vascular responses to phenylephrine, KCl and ACh of aortic rings from the female rabbits. 6. Both basal and ACh-stimulated release of nitrites from aortic rings was greater (P < 0.01) in vascular tissue from female than male rabbits. 7. These results indicate that differences in vascular reactivity in aortic rings from male and female rabbits may be associated with a higher release of NO, resulting in an increased vasodilator response in the female rabbits. PMID:8864537

Sánchez, A.; Gómez, M. J.; Dorantes, A. L.; Rosales, J. L.; Pastelín, G.; Díaz, V.; Posadas, F.; Escalante, B.

1996-01-01

180

Evaluation of 2.25Cr-1Mo Alloy for Containment of LiCl/KCl Eutectic during the Pyrometallurgical Processing of Used Nuclear Fuel  

SciTech Connect

Recovery of uranium from the Mk-IV and Mk-V electrorefiner vessels containing a LiCl/KCl eutectic salt has been on-going for 14 and 12 years, respectively, during the pyrometallurgical processing of used nuclear fuel. Although austenitic stainless steels are typically utilized for LiCl/KCl salt systems, the presence of cadmium in the Mk-IV electrorefiner dictates an alternate material. A 2.25Cr-1Mo alloy (ASME SA-387) was chosen due to the absence of nickel in the alloy which has a considerable solubility in cadmium. Using the transition metal impurities (iron, chromium, nickel, molybdenum, and manganese) in the electrorefined uranium products, an algorithm was developed to derive values for the contribution of the transition metals from the various input sources. Weight loss and corrosion rate data for the Mk-V electrorefiner vessel were then generated based on the transition metal impurities in the uranium products. To date, the corrosion rate of the 2.25Cr-1Mo alloy in LiCl/KCl eutectic is outstanding assuming uniform (i.e. non-localized) conditions.

B.R. Westphal; S.X. Li; G.L. Fredrickson; D. Vaden; T.A. Johnson; J.C. Wass

2011-03-01

181

Automated Potentiometric Titrations in KCl/Water-Saturated Octanol: Method for Quantifying Factors Influencing Ion-Pair Partitioning  

PubMed Central

The knowledge base of factors influencing ion pair partitioning is very sparse, primarily because of the difficulty in determining accurate log PI values of desirable low molecular weight (MW) reference compounds. We have developed a potentiometric titration procedure in KCl/water-saturated octanol that provides a link to log PI through the thermodynamic cycle of ionization and partitioning. These titrations have the advantage of being independent of the magnitude of log P, while maintaining a reproducibility of a few hundredths of a log P in the calculated difference between log P neutral and log P ion pair (diff (log PN???I)). Simple model compounds can be used. The titration procedure is described in detail, along with a program for calculating pKa?? values incorporating the ionization of water in octanol. Hydrogen bonding and steric factors have a greater influence on ion pairs than they do on neutral species, yet these factors are missing from current programs used to calculate log PI and log D. In contrast to the common assumption that diff (log PN???I) is the same for all amines, they can actually vary more than 3 log units, as in our examples. A major factor affecting log PI is the ability of water and the counterion to approach the charge center. Bulky substituents near the charge center have a negative influence on log PI. On the other hand, hydrogen bonding groups near the charge center have the opposite effect by lowering the free energy of the ion pair. The use of this titration method to determine substituent ion pair stabilization values (IPS) should bring about more accurate log D calculations and encourage species-specific QSAR involving log DN and log DI. This work also brings attention to the fascinating world of nature’s highly stabilized ion pairs. PMID:19265385

2009-01-01

182

Thermal-gradient migration of brine inclusions in salt crystals. [Synthetic single crystals of NaCl and KCl  

SciTech Connect

It has been proposed that high-level nuclear waste be disposed in a geologic repository. Natural-salt deposits, which are being considered for this purpose, contain a small volume fraction of water in the form of brine inclusions distributed throughout the salt. Radioactive-decay heating of the nuclear wastes will impose a temperature gradient on the surrounding salt which mobilizes the brine inclusions. Inclusions filled completely with brine migrate up the temperature gradient and eventually accumulate brine near the buried waste forms. The brine may slowly corrode or degrade the waste forms which is undesirable. In this work, thermal gradient migration of both all-liquid and gas-liquid inclusions was experimentally studied in synthetic single crystals of NaCl and KCl using a hot-stage attachment to an optical microscope which was capable of imposing temperature gradients and axial compressive loads on the crystals. The migration velocities of the inclusions were found to be dependent on temperature, temperature gradient, and inclusion shape and size. The velocities were also dictated by the interfacial mass transfer resistance at brine/solid interface. This interfacial resistance depends on the dislocation density in the crystal, which in turn, depends on the axial compressive loading of the crystal. At low axial loads, the dependence between the velocity and temperature gradient is non-linear.At high axial loads, however, the interfacial resistance is reduced and the migration velocity depends linearly on the temperature gradient. All-liquid inclusions filled with mixed brines were also studied. For gas-liquid inclusions, three different gas phases (helium, air and argon) were compared. Migration studies were also conducted on single crystallites of natural salt as well as in polycrystalline natural salt samples. The behavior of the inclusions at large angle grain boundaries was observed. 35 figures, 3 tables.

Yagnik, S.K.

1982-09-01

183

a Modified Denitrifying Bacteria Method for Dual Stable Isotopic Analysis of of Soil Nitrate in Kcl Extracts: Identification of Bioindicators of Nitrogen Deposition Along a Gradient in the Sonoran Desert  

NASA Astrophysics Data System (ADS)

Previous studies performing dual isotopic analysis of nitrate in KCl soil extracts using denitrifying bacteria have not incorporated alterations in the method to compensate for the increased N2O blank produced when the bacteria are exposed to KCl in solution. When 1M KCl is used as a blank, the amount of N2O released from the concentrated bacteria solution is more than four times as high as when using a DI water blank. The excess N2O produced is not an artifact of nitrate impurity in the KCl, although the blank increases with the molarity of KCl up to 1M. The introduction of N2O gas is significant enough to alter the values of IAEA USGS standards (3 ?g in 3ml KCl) which in turn results in an inaccurate regression for unknown samples. We reduced the size of the KCl blank and its effect on the standards by adding 3ml of KCl to the bacteria solution prior to purging the sample with He gas. This removes the N2O gas which is released by the bacteria when they initially come in contact with the KCl, and allows for standards to be calibrated to a precision of ± 0.1 % ?15N and ± 0.2 % ?18O. Using this new method, we measured ?15N and ?18O of nitrate in 1M KCl soil extracts taken from surface soil (5cm cores) along a nitrogen deposition gradient spanning the Coachella Valley in the western Sonoran Desert during the summer. Early germinating winter annual plant species (Schismus barbatus, Chaenactic fremontii, and Malacothrix glabrata) were collected as seedlings early in the growing season and again in late spring before senescence. Leaves from the dominant shrub, Larrea tridentata, were also collected from each site. Soil nitrogen from sites on the eastern edge of the valley had ?18O values between +30 and +41%, indicating an influence of atmospheric nitrate in plant available nitrate. There was an inverse correlation (r2=0.907) between soil ?18O and the ?15N of the C.fremontii leaf tissue, which suggests that in areas of high N deposition, some seedlings are able to take up excess nitrogen deposited to the soil surface in the summer. Leaf tissue from L. tridentata had a similar relationship with calculated summer atmospheric nitrogen deposition. These results indicate anthropogenic nitrate is only evident in the soils in areas of high deposition and that isotopic composition of the leaf tissue of some widespread species may be able to be used as a bioindicator of deposition.

Bell, M. D.; Sickman, J. O.; Allen, E. B.

2011-12-01

184

The WNK-regulated SPAK/OSR1 kinases directly phosphorylate and inhibit the K+–Cl? co-transporters  

PubMed Central

Precise homoeostasis of the intracellular concentration of Cl? is achieved via the co-ordinated activities of the Cl? influx and efflux. We demonstrate that the WNK (WNK lysine-deficient protein kinase)-activated SPAK (SPS1-related proline/alanine-rich kinase)/OSR1 (oxidative stress-responsive kinase 1) known to directly phosphorylate and stimulate the N[K]CCs (Na+–K+ ion co-transporters), also promote inhibition of the KCCs (K+–Cl? co-transporters) by directly phosphorylating a recently described C-terminal threonine residue conserved in all KCC isoforms [Site-2 (Thr1048)]. First, we demonstrate that SPAK and OSR1, in the presence of the MO25 regulatory subunit, robustly phosphorylates all KCC isoforms at Site-2 in vitro. Secondly, STOCK1S-50699, a WNK pathway inhibitor, suppresses SPAK/OSR1 activation and KCC3A Site-2 phosphorylation with similar efficiency. Thirdly, in ES (embryonic stem) cells lacking SPAK/OSR1 activity, endogenous phosphorylation of KCC isoforms at Site-2 is abolished and these cells display elevated basal activity of 86Rb+ uptake that was not markedly stimulated further by hypotonic high K+ conditions, consistent with KCC3A activation. Fourthly, a tight correlation exists between SPAK/OSR1 activity and the magnitude of KCC3A Site-2 phosphorylation. Lastly, a Site-2 alanine KCC3A mutant preventing SPAK/OSR1 phosphorylation exhibits increased activity. We also observe that KCCs are directly phosphorylated by SPAK/OSR1, at a novel Site-3 (Thr5 in KCC1/KCC3 and Thr6 in KCC2/KCC4), and a previously recognized KCC3-specific residue, Site-4 (Ser96). These data demonstrate that the WNK-regulated SPAK/OSR1 kinases directly phosphorylate the N[K]CCs and KCCs, promoting their stimulation and inhibition respectively. Given these reciprocal actions with anticipated net effects of increasing Cl? influx, we propose that the targeting of WNK–SPAK/OSR1 with kinase inhibitors might be a novel potent strategy to enhance cellular Cl? extrusion, with potential implications for the therapeutic modulation of epithelial and neuronal ion transport in human disease states. PMID:24393035

delos Heros, Paola; Alessi, Dario R.; Gourlay, Robert; Campbell, David G.; Deak, Maria; Macartney, Thomas J.; Kahle, Kristopher T.; Zhang, Jinwei

2014-01-01

185

Author's personal copy Journal of Power Sources 172 (2007) 908912  

E-print Network

Tin phosphates with various mesopore ratios were pre- pared by mixing various amounts of SnF2 and H3PO was added to the SnF2/H3PO4 solution. The molar ratio of SnF2/H3PO4 was fixed at 1.35, while CTAB/H3PO4

Park, Byungwoo

2007-01-01

186

Phorbol ester attenuates the KCl-induced increase in (Ca/sup 2 +/) and inhibits spontaneous sarcoplasmic reticulum Ca/sup 2 +/ release, in rat cardiac myocytes  

SciTech Connect

Partial membrane depolarization induced by increasing the KCl concentration of the medium bathing cardiac myocytes leads to an increase in cell (Ca/sup 2 +/), and accelerates the frequency of spontaneous contractile waves (W) caused by periodic sarcoplasmic reticulum (SR) Ca/sup 2 +/ release. In suspensions of myocytes bathed in 1.0mM Ca/sup 2 +/ at 37 (pH 7.4) and loaded with the fluorescent Ca/sup 2 +/ - indicator Fura-2, by incubation with 2 ..mu..M acetoxymethyl ester for 30 min, the addition of KCl to raise (K/sup +/) from 5 to 30 mM is associated with a rapid (< 10 sec) increase in fluorescence, corresponding to an increased cell (Ca/sup 2 +/). Prior exposure (3 min) to 10/sup -7/ M phorbol myristate acetate (PMA) diminishes this response to 44 +/- 10% of that in control suspensions (n = 9). Under the same conditions W frequency (min/sup -1/) in individual cells in 30 mM KCl averaged 8.3 +/- 0.6. Addition of PMA abolished W within 1 min. Diacylglycerol (10 ..mu..M L..cap alpha..-1,2-dioctanoylglycerol, di C8) had a similar effect on W frequency. The thesis is that PMA attenuates cell Ca/sup 2 +/ overload and its associated potentiation of spontaneous SR Ca/sup 2 +/ oscillations. In view of the efficacy of PMA and di C8, it is suggested that the effect is mediated by protein kinase c, and it may involve an alteration in the intracellular distribution of this enzyme.

Hansford, R.G.; Capogrossi, M.C.; Kaku, T.; Pelto, D.J.; Filburn, C.H.; Lakatta, E.G.

1986-03-01

187

Stimulation of Human Erythrocyte K-Cl Cotransport and Protein Phosphatase Type 2A by n-Ethylmaleimide: Role of Intracellular Mg ++  

Microsoft Academic Search

.   An increase in the activity of membrane-associated protein phosphatase type 1 (mb-PP1) is associated with stimulation of\\u000a erythrocyte K-Cl cotransport (KCC). We have recently proposed that membrane-associated protein phosphatase type 2A (mb-PP2A)\\u000a is also involved in KCC regulation by cell swelling (Bize et al., 1999. Am. J. Physiol.\\u000a \\u000a 277:C899–C912). We used two protein phosphatase inhibitors, okadaic acid (OA) and

I. Bize; B. Güvenç; G. Buchbinder; C. Brugnara

2000-01-01

188

Extensive Lesions in Rat Insular Cortex Significantly Disrupt Taste Sensitivity to NaCl and KCl and Slow Salt Discrimination Learning  

PubMed Central

While studies of the gustatory cortex (GC) mostly focus on its role in taste aversion learning and memory, the necessity of GC for other fundamental taste-guided behaviors remains largely untested. Here, rats with either excitotoxic lesions targeting GC (n = 26) or sham lesions (n = 14) were assessed for postsurgical retention of a presurgically LiCl-induced conditioned taste aversion (CTA) to 0.1M sucrose using a brief-access taste generalization test in a gustometer. The same animals were then trained in a two-response operant taste detection task and psychophysically tested for their salt (NaCl or KCl) sensitivity. Next, the rats were trained and tested in a NaCl vs. KCl taste discrimination task with concentrations varied. Rats meeting our histological inclusion criterion had large lesions (resulting in a group averaging 80% damage to GC and involving surrounding regions) and showed impaired postsurgical expression of the presurgical CTA (LiCl-injected, n = 9), demonstrated rightward shifts in the NaCl (0.54 log10 shift) and KCl (0.35 log10 shift) psychometric functions, and displayed retarded salt discrimination acquisition (n = 18), but eventually learned and performed the discrimination comparable to sham-operated animals. Interestingly, the degree of deficit between tasks correlated only modestly, if at all, suggesting that idiosyncratic differences in insular cortex lesion topography were the root of the individual differences in the behavioral effects demonstrated here. This latter finding hints at some degree of interanimal variation in the functional topography of insular cortex. Overall, GC appears to be necessary to maintain normal taste sensitivity to NaCl and KCl and for salt discrimination learning. However, higher salt concentrations can be detected and discriminated by rats with extensive damage to GC suggesting that the other resources of the gustatory system are sufficient to maintain partial competence in these tasks, supporting the view that such basic sensory-discriminative taste functions involve distributed processes among central gustatory structures. PMID:25658323

Blonde, Ginger D.; Bales, Michelle B.; Spector, Alan C.

2015-01-01

189

A comparison of the effects of various sex steroids on cholecystokinin- and KCl-induced tension in female guinea pig gallbladder strips.  

PubMed

Estrogen (E) has been shown to have an inhibitory effect on the contractility of gastrointestinal smooth muscle, including the gallbladder. During pregnancy E and progesterone (P) levels are elevated. A biliary stasis may develop during pregnancy that is characterized by an increase in the fasting and residual volumes and by a decrease in emptying capacity. This study investigates the effect of 17?-estradiol (E2), dihydrotestosterone (DHT), P, 17-hydroxyprogesterone (17-P), and a P metabolite, 20?-hydroxyprogesterone (20-P) on contraction in female guinea pig gallbladder strips. DHT, P, 17-P, 20-P, and E2 each induced a concentration-dependent relaxation of cholecystokinin octapeptide (CCK) induced tension. DHT, E2, and P also induced a concentration-dependent relaxation of KCl-induced tension. When the response to E2 was compared to strips from young female guinea pigs with those taken from guinea pigs in late pregnancy, there was no significant difference in the response to either 50 or 100 ?M E2; however, 10 ?M E2 caused a significant increase (p<0.05) in the amount of relaxation in strips from pregnant guinea pigs. Treatment of the strips from young guinea pigs with PKA inhibitor 14-22 amide myristolated had no significant effect on the E2-induced relaxation. Treatment of the strips with 2-APB, an inhibitor of IP3 induced Ca(2+) release, produced a significant (p<0.001) increase in the amount of E2-induced relaxation when either CCK or KCl were used. Neither KT5823, a PKG inhibitor, nor L-NMMA, a nitric oxide (NO) synthase inhibitor, had a significant effect on the E2-induced relaxation. Bisindolymaleimide IV and chelerythrine Cl(-), PKC blockers, were used in combination with no significant effect on the amount of CCK-induced tension, but significantly (p<0.01) increased the amount of E2-induced relaxation. When either E2 or P were added to the chambers 3 min prior to either CCK or KCl, a significant decrease (p<0.001) in the amount of tension generated was observed. The inhibition of extracellular Ca(2+) entry mediates both P-induced and E2-induced relaxation of CCK- and KCl-induced tension in female guinea pig gallbladder strips. PMID:23399969

Kline, Loren; Karpinski, Edward

2013-05-01

190

Precise coulometric titration of precious metals III. Determination of gold (III) with electrogenerated chlorocuprous ion in KCl-Cu-EDTA buffer medium.  

PubMed

A method for the precise coulometric titration of gold (III) with electrogenerated chlorocuprous ion in KCl-Cu-EDTA buffer medium is described. 7.45-16.8 mg of gold can be determined with potentiometric end-point detection (RSD = 0.04%). The method is applied to precise analysis of gold in pure gold, jewellery and gold alloys with good selectivity. The mechanism of electron exchange at the gold-plated platinum cathode-electrolyte interface during the process of titration and the reversibility of the electrode in the proposed electrolyte are discussed. PMID:18966587

Dong, S; Yang, X

1996-07-01

191

The role of F A1:Ag+ defects in laser light generation and coadsorption of CO and halogen atoms at the KCl and KBr surface sites. First principles calculations  

NASA Astrophysics Data System (ADS)

FA1:Ag+ color center at the low coordination (100) and (110) surface sites of KCl and KBr thin films play an important role in providing tunable laser oscillation and adsorbatesubstrate interactions. Double-well potentials at this site are investigated using ab initio molecular electronic structure calculations. The calculated Stokes shifted (optical transition bands), opticaloptical conversion efficiencies, the probability of orientational destruction, exciton (energy) transfer and Glasner-Tompkins empirical rule suggest that laser light generation is sensitive to (i) the lattice anion, (ii) the coordination number of surface ions, and (iii) the choice of the basis set centered on the anion vacancy. The adsorbate-substrate interactions were found to be dependent on the electronegativity of the adatom and on the lattice anion. Optimised geometries and the coadsorption of CO and (F, Cl, Br, I) on KCl and KBr (100) crystals are presented. Calculated chemisorption energies for CO on the (halogen atom/defect free sites of KCl and KBr (100) crystals) showed that the coadsorption of halogen atom tends to block other adsorbate-substrate interactions at the nearest neighbour sites. Thus if halogen atom coverage increases, the CO prefers to be adsorbed on the K+ site of the KCl and KBr (100) surfaces and on KBr relative to KCl.

Abdelrazik, Safaa; Shalabi, Ahmed

2007-12-01

192

Separation of CsCl from a Ternary CsCl-LiCl-KCl Salt via a Melt Crystallization Technique for Pyroprocessing Waste Minimization  

SciTech Connect

A parametric study has been conducted to identify the effects of several parameters on the separation of CsCl from molten LiCl-KCl salt via a melt crystallization process. A reverse vertical Bridgman technique was used to grow the salt crystals. The investigated parameters were: (1) the advancement rate, (2) the crucible lid configuration, (3) the amount of salt mixture, (4) the initial composition of CsCl, and (5) the temperature difference between the high and low furnace zones. From each grown crystal, samples were taken axially and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Results show that CsCl concentrations at the top of the crystals were low and increased to a maximum at the bottom of the salt. Salt (LiCl-KCl) recycle percentages for the experiments ranged from 50% to 75% and the CsCl composition in the waste salt was low. To increase the recycle percentage and the concentration of CsCl in the waste form, the possibility of using multiple crystallization stages was explored to further optimize the process. Results show that multiple crystallization stages are practical and the optimal experimental conditions should be operated at 5.0 mm/hr rate with a lid configuration and temperature difference of 200 °C for a total of five crystallization stages. Under these conditions, up to 88% of the salt can be recycled.

Ammon Williams; Supathorn Phongikaroon; Michael Simpson

2013-02-01

193

Design of highly sensitive phosphorescence sensor for determination of procaterol hydrochloride based on inhibition of KClO3 oxidation fluorescein isothiocyanate.  

PubMed

Procaterol hydrochloride (Prh) can inhibit KClO3 oxidation of fluorescein isothiocyanate (FITC) to form a non-phosphorescent compound, which causes room temperature phosphorescence (RTP) of FITC in the system to enhance sharply the linear relationship between ?Ip and the Prh content. Thus, a rapid response and highly sensitive phosphorescence sensor for the determination of Prh has been developed based on the inhibiting effect of Prh on KClO3 oxidation of FITC. This simple, high sensitivity (detection limit (LD) calculated by 3Sb /k was 0.019 fg/spot, sample volume 0.40 µl, corresponding concentration 4.8?×?10(-14) g ml(-1) ) and selective sensor with a wide linear range (0.080-11.20 g/spot) has been applied to detect Prh in blood samples, and the results were consistent with those obtained by high-performance liquid chromatography (HPLC). Simultaneously, the mechanism of the phosphorescence sensor for the detection of Prh was also investigated using infrared spectroscopy. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25044504

Liu, Jia-Ming; Huang, Qitong; Liu, Zhen-Bo; Zhang, Li-Hong; Zheng, Zhi-Yong; Lin, Chang-Qing

2015-06-01

194

Synthesis of rare earth phosphates in molten LiCl KCl eutectic: Application to preliminary treatment of chlorinated waste streams containing fission products  

NASA Astrophysics Data System (ADS)

The precipitation of rare earth phosphates (RE = La, Ce, Pr, Nd, and Lu), from RECl 3 was investigated in molten LiCl-KCl eutectic at 500 °C in air. Ammonium dihydrogenphosphate (NH 4H 2PO 4) was used as the phosphorus precursor. X-ray diffraction analysis indicated the formation of compounds with monazite (La, Ce, Pr, and Nd) or xenotime (Lu) structures. 31P NMR spectroscopy measurements confirmed that lanthanum formed pure monazite, which indicates a LaCl 3 ? LaPO 4 conversion factor near 100%. These results demonstrate that the stoichiometric addition of NH 4H 2PO 4 is sufficient to obtain quantitative precipitation at 500 °C of anhydrous rare earth phosphates in molten LiCl-KCl. The use of this type of precursor, which has the advantage of not modifying the chemical composition of the medium after recovery of the rare earth phosphates, could be considered during the first step of purification of chlorinated baths containing fission products arising from spent fuel reprocessing by a pyrochemical process.

Hudry, Damien; Bardez, Isabelle; Rakhmatullin, Aydar; Bessada, Catherine; Bart, Florence; Jobic, Stéphane; Deniard, Philippe

2008-11-01

195

Evaluation of the Electrochemical Behavior of CeCl3 in Molten LiCl-KCl Eutectic Utilizing Metallic Ce as an Anode  

SciTech Connect

A study of the electrochemical behavior of CeCl3 in LiCl-KCl eutectic was performed in the temperature range 653-973K to ascertain if CeCl3 is a suitable surrogate for UCl3 in the development of nuclear fuel cycle technologies. Reduction of cerium occurs in a single 3-electron step that is quasi-reversible. The diffusion coefficient of Ce(III) was determined by linear sweep voltammetry and chronopotentiometry. The standard potential of Ce(III)/Ce(0) was measured and used to calculate Gibbs free energy and the activity coefficient. The nucleation of cerium on a tungsten substrate was determined to be instantaneous with hemispherical nuclei whose growth is controlled by linear or hemispherical diffusion. The order of magnitude of the exchange current density was determined by the linear polarization method. The electrochemical characteristics of CeCl3 were compared with those of UCl3 in LiCl-KCl to evaluate the potential of cerium as a surrogate for uranium electrorefining development.

K. C. Marsden; B. Pesic

2011-04-01

196

Numerical Modeling of In-situ Reaction Barrier by Injection of Ca(OH)2 Solution for CO2 Geological Storage  

Microsoft Academic Search

Containment of CO2 in the storage reservoir is a very important issue. We present here an in-situ reaction barrier method to reduce the medium permeability along potential leakage paths of a deep CO2 storage reservoir in a saline formation. An aqueous solution will be injected into the fractures and rocks through injection wells. The solution will have a low viscosity

T. Xu; T. Ito

2008-01-01

197

An experimental study of the solubility of molybdenum in H[subscript 2]O and KCl?H2O solutions from 500 [degrees]C to 800 [degrees]C, and 150 to 300 MPa  

SciTech Connect

The solubility of molybdenum (Mo) was determined at temperatures from 500 C to 800 C and 150 to 300 MPa in KCl-H{sub 2}O and pure H{sub 2}O solutions in cold-seal experiments. The solutions were trapped as synthetic fluid inclusions in quartz at experimental conditions, and analyzed by laser ablation inductively coupled plasma mass spectrometry (LA ICPMS). Mo solubilities of 1.6 wt% in the case of KCl-bearing aqueous solutions and up to 0.8 wt% in pure H{sub 2}O were found. Mo solubility is temperature dependent, but not pressure dependent over the investigated range, and correlates positively with salinity (KCl concentration). Molar ratios of {approx}1 for Mo/Cl and Mo/K are derived based on our data. In combination with results of synchrotron X-ray absorption spectroscopy of individual fluid inclusions, it is suggested that Mo-oxo-chloride complexes are present at high salinity (>20 wt% KCl) and ion pairs at moderate to low salinity (<11 wt% KCl) in KCl-H{sub 2}O aqueous solutions. Similarly, in the pure H{sub 2}O experiments molybdic acid is the dominant species in aqueous solution. The results of these hydrothermal Mo experiments fit with earlier studies conducted at lower temperatures and indicate that high Mo concentrations can be transported in aqueous solutions. Therefore, the Mo concentration in aqueous fluids seems not to be the limiting factor for ore formation, whereas precipitation processes and the availability of sulfur appear to be the main controlling factors in the formation of molybdenite (MoS{sub 2}).

Ulrich, Thomas; Mavrogenes, John (Australian National University)

2008-04-22

198

Vapor-liquid phase equilibria of potassium chloride-water mixtures: Equation-of-state representation for KCl-H2O and NaCl-H2O  

USGS Publications Warehouse

Measurements of isothermal vapor-liquid compositions for KCl-H2O as a function of pressure are reported. An equation of state, which was originally proposed by Pitzer and was improved and used by Tanger and Pitzer to fit the vapor-liquid coexistence surface for NaCl-H2O, has been used for representation of the KCl-H2O system from 300 to 410??C. Improved parameters are also reported for NaCl-H2O from 300 to 500??C. ?? 1990 American Chemical Society.

Hovey, J.K.; Pitzer, K.S.; Tanger, J.C., IV; Bischoff, J.L.; Rosenbauer, R.J.

1990-01-01

199

Vapor-liquid phase equilibria of potassium chloride-water mixtures: Equation-of-state representation for KCl-H sub 2 O and NaCl-H sub 2 O  

SciTech Connect

Measurements of isothermal vapor-liquid compositions for KCl-H{sub 2}O as a function of pressure are reported. An equation of state, which was originally proposed by Pitzer and was improved and used by Tanger and Pitzer to fit the vapor-liquid coexistence surface for NaCl-H{sub 2}O, has been used for representation of the KCl-H{sub 2}O system from 300 to 410{degree}C. Improve parameters are also reported for NaCl-H{sub 2}O from 300 to 500{degree}C.

Hovey, J.K.; Pitzer, K.S.; Tanger, J.C. IV (Lawrence Berkeley Lab., CA (USA)); Bischoff, J.L.; Rosenbauer, R.J. (Geological Survey, Menlo Park, CA (USA))

1990-02-08

200

Flexible electromagnetic wave sensor operating at GHz frequencies for instantaneous concentration measurements of NaCl, KCl, MnCl2 and CuCl solutions  

NASA Astrophysics Data System (ADS)

A novel electromagnetic wave sensor operating at GHz frequencies for real-time chlorides concentration analysis is reported. The sensor response to deionized water, NaCl, KCl, MnCl2 and CuCl solutions at various concentrations was tested. The sensing element, in the form of a silver pattern antenna that emits an electromagnetic field, was printed on a polyimide flexible laminate substrate to form a sensor to suit a broad range of applications, where a sensor could be placed in water reservoirs or fluid-carrying pipes for continuous analysis. The developed system confirmed the viability of using microwaves for real-time chloride solutions monitoring as the reflected signals represented by S11 parameters were unique with clearly observed shifts in the resonant frequencies and amplitude changes when placed in direct contact with 20 µl of each solution. This paper was an invited article at the Sensors and Applications XVII conference.

Korostynska, O.; Ortoneda-Pedrola, M.; Mason, A.; Al-Shamma'a, A. I.

2014-06-01

201

The Resveratrol-induced Relaxation of Cholecystokinin Octapeptide- or KCl-induced Tension in Male Guinea Pig Gallbladder Strips Is Mediated Through L-type Ca2+ Channels  

PubMed Central

Background/Aims Resveratrol (3,5,4?-trihydroxystilbene) is a polyphenolic compound (stilbene) and a phytoalexin. The purpose of this study was to determine the mechanism which mediated the resveratrol-induced relaxation of cholecystokinin octapeptide- or KCl-induced tension in male guinea pig gallbladder strips. Methods Gallbladder strips were prepared and suspended in in vitro chambers filled with Krebs-Henseleit solution. The strips were attached to force displacement transducers, and the changes in tension were recorded on a polygraph. All reagents were added directly into the chambers. Results To determine if intracellular Ca2+ release mediated the resveratrol-induced relaxation of cholecystokinin octapeptide-induced tension, 2-aminoethoxydiphenylborane (2-APB) was used. 2-APB significantly (P < 0.01) decreased the amount of RSVL-induced relaxation. To determine if protein kinase A (PKA) mediated the resveratrol-induced relaxation, PKA inhibitor 14-22 amide myristolated (PKA-IM) was used. PKA-IM had no effect on resveratrol-induced relaxation. Neither KT5823, NG-methyl-L-arginine acetate salt, a nitric oxide synthase inhibitor, nor fulvestrant had a significant effect on the amount of resveratrol-induced relaxation. Genistein, a protein tyrosine kinase inhibitor, significantly (P < 0.01) increased the RSVL-induced relaxation. To determine if protein kinase C mediated the RSVL-induced relaxation, the protein kinase C inhibitors bisindolymaleimide IV and chelerythrine Cl- were used together, and a significant (P < 0.05) increase in resveratrol-induced relaxation was observed. The pretreatment of the strips with resveratrol significantly (P < 0.001) decreased the amount of KCl- and cholecystokinin octapep-tide-induced tension. Conclusions Resveratrol-induced relaxation is mediated by its effects on L-type Ca2+ channels and intracellular Ca2+ release. PMID:25537678

Kline, Loren W; Karpinski, Edward

2015-01-01

202

High temperature decomposition of synthetic hydroxyapatite in vacuum  

NASA Astrophysics Data System (ADS)

Starting hydroxyapatite (HA) powders were prepared by chemical synthesis at 40 °C using analytical-grade reagents: Ca(OH)2 and H3PO4. The process of thermal decomposition of HA powders was followed by thermo-XRD in vacuum 10-4 torr. The results show that synthetic HA with a CaP ratio=1.67 is stable below 1100 °C. Beyond 1100 °C HA gradually is transformed into Oxiapatite. In the region of 1400 °C a thermal structural configuration Monoclinic-P was detected with the following parameters: d=3.095x, 2.9593, 2.8602, 3.9521, 2.7161, 2.6121, 2.8541, etc. During the cooling process in normal atmosphere, this configuration is transformed into Ca2P2O7, Ca3(PO4)2 and Ca4P2O9. It can be considered as an important element for the interpretation of HA decomposition mechanism.

Prieto Valdés, J. J.; Gomez, G.; Pacheco, G.; Montoya, J. A.

1996-07-01

203

Fibrous growth of tricalcium phosphate ceramics.  

PubMed

Structural transformation and sintering processes of tricalcium phosphate (TCP) ceramics prepared from defective hydroxyapatite (Ca9HPO4(PO4)5OH) were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). Starting powders with Ca/P ratio approximately 1.5 were obtained by adding 0.5 l of 0.3 M H3PO4 solution to an equal volume of 0.45 M Ca(OH)2. In the prepared ceramics, the onset temperature for transformation of defective hydroxyapatite into TCP (witlokite) agrees with the onset temperature for sintering (800 degrees C). Sintering occurs through the formation of a fibrous structure, which resembles biological hard tissue. In the 1000-1200 degrees C range, these fibres coalesce into grains of up to 0.6 microm in size with a fibrous-laminar morphology. At the end of this sintering stage witlokite transforms into alphaTCP. At about 1450 degrees C, partial decomposition of alphaTCP into Ca2P2O7+Ca4P2O9 is observed. AFM observations suggest that Ca2P2O7 is segregated in the liquid state and increases the velocity of grain growth (up to 12 microm). PMID:15348752

Prieto Valdés, J J; Ortiz López, J; Rueda Morales, G; Pacheco Malagon, G; Prieto Gortcheva, V

1997-05-01

204

Synthesis of fluorine substituted hydroxyapatite nanopowders and application of the central composite design for determination of its antimicrobial effects  

NASA Astrophysics Data System (ADS)

Synthetic biomaterials based on fluorine substituted hydroxyapatite are potentially attractive for orthopedic and dental implant applications. The new synthesis of fluorine substituted hydroxyapatite samples were done by neutralization, which consists of adding the solution of HF and H3PO4 in suspension of Ca(OH)2. Characterization studies from XRD, SEM and FTIR spectra showed that crystals are obtained with apatite structure and those particles of all samples are nano size, with an average length of 80 nm and about 15-25 nm in diameter. The central composite design was used in order to determine the optimal conditions for the antimicrobial activity of the synthesized samples. In order to evaluate the influence of operating parameters on the percent of viable cell reduction of Streptococcus mutans, three independent variables were chosen: exposure time, pH of saline and floride concentration in apatite samples. The experimental and predicted antimicrobial activities were in close agreement. Antimicrobial activity of the samples increases with the increase of fluoride concentration and the decreased pH of saline. The maximum antimicrobial activity was achieved at the initial pH of 4.

Stani?, Vojislav; Dimitrijevi?, Suzana; Antonovi?, Dušan G.; Joki?, Bojan M.; Zec, Slavica P.; Tanaskovi?, Sladjana T.; Rai?evi?, Slavica

2014-01-01

205

Thermoluminescence response of new KCl(X)Br(1-X):EuCl3 sintered phosphors exposed to beta and gamma radiation.  

PubMed

Alkali halides crystals have been the subject of intense research for an understanding of their radiation-induced defects and luminescence properties. They exhibit noteworthy thermoluminescence (TL) properties when exposed to ionising radiation. Currently, these materials are grown employing expensive and rather complicated techniques. In this work, the results on the TL properties of new alkali halides phosphors fabricated by a simple and inexpensive procedure are presented. The samples were made by mixing KCl, KBr and EuCl3 salts, and compressing them at a pressure of 3.2 x 10(7) Pa during 3 min, followed by sintering at 700 degrees C during 24 h under air atmosphere. The dosimetric response of the samples showed an increase with radiation dose in the 1.5-20.0 Gy dose range for beta and gamma radiation. The TL glow curves in sintered samples presented significant differences in their peak structures compared with monocrystalline samples, indicating that the nature of the trapping states and the recombination mechanisms may be different. PMID:16702244

Bernal, R; Cruz-Zaragoza, E; Cruz-Vázquez, C; Burruel-Ibarra, S E; Rivera-Flores, M J; Barboza-Flores, M

2006-01-01

206

The Electrochemical Formation of Ni-Tb Intermetallic Compounds on a Nickel Electrode in the LiCl-KCl Eutectic Melts  

NASA Astrophysics Data System (ADS)

The work presents an electrochemical study on the formation of Ni-Tb intermetallic compounds in the LiCl-KCl-TbCl3 melts on tungsten and nickel electrodes at 773 K (500 °C) by electrochemical techniques. For a tungsten electrode, cyclic voltammetry and square-wave voltammetry showed that the electrochemical reduction of Tb(III) proceeded in a one-step process involving three electrons at -2.06 V ( vs Ag/AgCl). For a nickel electrode, the reduction potential of Tb(III)/Tb was observed at more positive values than those on W electrode by cyclic voltammetry, due to the formation of Ni-Tb intermetallic compounds. Square-wave voltammetry and open-circuit chronopotentiometry put into evidence the formation of intermetallic compounds at around -1.27, -1.63, and -1.88 V, respectively. Three alloy samples were obtained by potentiostatic electrolysis on a Ni electrode at various potentials and analyzed by X-ray diffraction, scanning electron micrograph, and energy-dispersive spectrometry. The analysis results confirmed the formation of Ni17Tb2, Ni5Tb, and Ni2Tb alloy compounds.

Han, Wei; Sheng, Qingnan; Zhang, Milin; Li, Mei; Sun, Tingting; Liu, Yaochen; Ye, Ke; Yan, Yongde; Wang, Yingcai

2014-06-01

207

Determination of the E-pO 2- stability diagram of plutonium in the molten LiCl-KCl eutectic at 450 °C  

NASA Astrophysics Data System (ADS)

Plutonium trichloride solution in the molten LiCl-KCl eutectic was prepared by carbochlorination of plutonium oxide. Kinetics of this reaction was compared in different conditions in the range of 443-550 °C. Using this molten salt solution, the redox potential of the Pu(III)/Pu couple at inert tungsten electrode was measured at 450 °C by electromotive force measurement and was found to be E' ? = -2.76 V vs. the Cl 2(g)(1 atm)/Cl - reference electrode (molar fraction scale). Reaction between plutonium trichloride and oxide ions was studied by potentiometric titration, using yttria stabilized electrodes. In our experimental conditions, the titration curves indicate the precipitation of the sesquioxide Pu 2O 3. The solubility product cologarithm calculated from these curves is found to be p Ks(Pu 2O 3) = 22.8 ± 1.1 (molality scale). Using the experimentally obtained values for E' ?, activity coefficient and p Ks joined to the published thermodynamic data, the stability phase diagram of the Pu-O species was then drawn.

Caravaca, Concha; Laplace, Annabelle; Vermeulen, Jackie; Lacquement, Jérôme

2008-07-01

208

Mechanisms Underlying a Decrease in KCl-Induced Contraction after Long-Term Serum-Free Organ Culture of Rat Isolated Mesenteric Artery  

PubMed Central

ABSTRACT Organ culture of blood vessel is a better technique to investigate the long-term effects of drugs. However, some functional changes may occur from freshly isolated vessel (Fresh). Mammalian/mechanistic target of rapamycin (mTOR) regulates smooth muscle differentiation and Ca2+ mobilization. We thus investigated mechanisms of alteration in smooth muscle contractility after serum-free organ culture focusing on mTOR. Rat isolated mesenteric arteries were cultured for 5 days without (0% serum) or with rapamycin. In 0% serum, absolute contraction by KCl significantly decreased from Fresh, which was significantly rescued by rapamycin. In 0% serum, mTOR expression significantly increased from Fresh, which was significantly rescued by rapamycin. In 0% serum, expression of myocardin, a key regulator of smooth muscle differentiation markers, significantly decreased from Fresh, which was significantly rescued by rapamycin. However, the decrease in expression of contractile proteins, including SM22? and calponin, was not changed by rapamycin. Basal phosphorylation of calmodulin-dependent protein kinase II significantly increased in 0% serum, which was significantly rescued by rapamycin. In 0% serum, absolute contraction by caffeine significantly decreased from Fresh, which was significantly rescued by rapamycin. In conclusion, expression of mTOR increased during serum-free organ culture of rat isolated mesenteric artery for 5 days, which may be at least partly responsible for the decreased smooth muscle contractility perhaps due to the decrease in the stored Ca2+ in smooth muscle. PMID:24694942

MORITA, Tomoka; OKADA, Muneyoshi; YAMAWAKI, Hideyuki

2014-01-01

209

Convective solution transport -- An improved technique for the growth of big crystals of the superconducting {alpha}-FeSe using KCl as solvent  

SciTech Connect

An improved technique of convective solution transport using KCl as solvent at 840-790 deg. C (where mass transport takes place across a vertical temperature gradient) is described for the growth of crystals of the recently discovered superconductor {alpha}-FeSe{sub x} (x = 1-0.8). The crystals were annealed in situ at 400-350 deg. C for 20-30 h to improve the superconducting properties. Hexagonal plate like crystals measuring 5-6 mm across and 0.25-0.5 mm thick were obtained. High resolution transmission electron microscopy (HRTEM) measurements show good crystallinity and the energy dispersive x-ray analysis (EDX) gives a composition very close to the starting powders. The zero resistance temperature of the crystals was found to increase from 6.5 to 9 K as the composition is decreased from x = 0.95 to 0.9 and decrease thereafter. Similar behavior was also observed in the powder x-ray diffraction (XRD) patterns and Raman spectra with the main peak shifting to higher value until 0.9 and decrease thereafter. In addition the XRD patterns show reducing hexagonal phase reflections as x decreases to 0.9. Anisotropic magnetic behavior was observed when the magnetic field is applied parallel and perpendicular to the (101) face.

Rao, S. M.; Ling, M. C.; Ke, C. T.; Chen, T. C.; Chen, C. L.; Huang, T. W.; Wu, M. K. [Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Mok, B. H.; Wu, T. B. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Tsai, I.-M.; Lin, Y.-L.; Liu, H. L. [Department of Physics, National Taiwan Normal University, Taipei, Taiwan (China); Hsu, F. C. [Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China)

2011-12-01

210

Ovariectomy modulation of morphine analgesia of neuropathic pain is associated with the change of K(+)-Cl(-) cotransporter 2 protein level in spinal dorsal horn.  

PubMed

Sex differences in opioid analgesia have been confirmed both in clinical and experimental studies. Gonadal hormones (estrogens in particular) have a great role in this process. However, the mechanisms that underlie these sex differences are not very clear. In this study, we used K(+)-Cl(-) cotransporter 2 (KCC2) as a molecule target to investigate the mechanism underlying the phenomenon. Sprague-Dawley rats were randomly assigned to ovariectomy (OVX)+morphine group, OVX+Saline group, sham surgery (OVX-sham)+morphine group and OVX-sham+saline group. All the rats received SNI surgery three weeks after ovariectomy. We used von Frey values as a sign of neuropathic pain. On PO day 14, 1 ?g morphine or the vehicle saline was administered intrathecally via a PE-10 catheter formerly implanted. Hindpaw withdrawal threshold was determined before and 30, 60, 90, 120, 150, 180 min after drugs injection. The L4-L5 segments of the spinal cord were removed and immunoblotted for KCC2 protein at the time of 2 and 3 h after drugs administration. We find that ovariectomy can regulate the sensitivity to morphine analgesia of neuropathic pain and KCC2 protein level will change in the spinal dorsal horn. PMID:25419384

Shen, Weijun; Shen, Liang; Chen, Guoqiang; Wang, Fen; Li, Cheng; Lin, Fuqing; Yang, Xiaohu; Fu, Shukun

2014-01-01

211

Effet de sel sur l'équilibre liquide-liquide des systèmes eau-phénol-sel (KCl, NaCl, LiCl, CaCl2 et MgCl2)  

NASA Astrophysics Data System (ADS)

Phase diagrams of the Water-Phenol-Salt systems (KCl, NaCl, LiCl, CaCl2 and MgCl2) have been studied. The influence of the cation concentration and ionic radius on the binodal curves and the maxima critical point coordinates bas been shown. Les diagrammes de phases de l'équilibre liquide-liquide des systèmes Eau-Phénol-Sel (KCl, NaCl, LiCl, CaCl2 et MgCl2) ont été étudiés. Nous avons mis en évidence l'influence de la concentration et du rayon ionique du cation du sel ajouté sur l'allure des courbes binodales et les coordonnées des points critiques maxima de miscibilité.

Belhachemi, B.; Gotouk, A. A.

1999-07-01

212

Thermodynamic evaluation and optimization of the LiCl-NaCl-KCl-RbCl-CsCl-MgCl2-CaCl2 system using the modified quasi-chemical model  

NASA Astrophysics Data System (ADS)

A complete critical evaluation of all available phase-diagram and thermodynamic data has been performed for all condensed phases of the LiCl-NaCl-KCl-RbCl-CsCl-MgCl2-CaCl2 system, and optimized model parameters have been found. The model parameters obtained for binary and ternary subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent system. The modified quasi-chemical model for short-range ordering was used for the molten salt phase. Particularly in solutions with MgCl2 and KCl, RbCl, or CsCl, the calculations indicate a large dregree of ordering on the cationic sublattice, with Mg-Alkali second-nearest-neighbor pairs being favored.

Pelton, Arthur D.; Chartrand, Patrice

2001-06-01

213

Molecular dynamics simulations of aqueous NaCl and KCl solutions: Effects of ion concentration on the single-particle, pair, and collective dynamical properties of ions and water molecules  

Microsoft Academic Search

We have performed a series of molecular dynamics simulations of aqueous NaCl and KCl solutions at different concentrations, ranging from 0 M to 4.5 M, to investigate the effects of ion concentration on the single-particle, pair, and collective dynamical properties of aqueous electrolyte solutions. The SPC\\/E model is used for water and the ions are modeled as charged Lennard-Jones particles.

Snehasis Chowdhuri; Amalendu Chandra

2001-01-01

214

Thiol-dependent passive K:Cl transport in sheep red blood cells: IX. Modulation by pH in the presence and absence of DIDS and the effect of NEM  

Microsoft Academic Search

Summary Recently we proposed that cytoplasmic acidification of low K+ (LK) sheep erythrocytes may stimulate ouabain-resistant Cl--dependent K+ flux (K+:Cl- cotransport), also known to be activated by cell swelling, treatment with N-ethylmaleimide (NEM), or removal of cellular bivalent cations. Here we studied the dependence of K+ transport on intracellular and extracellular pH (pHi, pHo) varied either simultaneously or independently using

A. M. M. Zade-Oppen; P. K. Lauf

1990-01-01

215

Metastable phase equilibria in the systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K  

NASA Astrophysics Data System (ADS)

Experimental studies on the metastable solubilities and physicochemical properties (density and refractive index) in the ternary systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K were determined with the method of isothermal evaporation. According to the experimental results, the phase diagrams of the two ternary systems were plotted. In the phase diagrams, there are both two isotherm evaporation curves, one eutectic point corresponding to K2SO4 + K2B4O7 · 4H2O, and KCl + K2B4O7 · 4H2O, respectively. Both of the ternary systems belong to a simple eutectic type, and neither double salts nor solid solutions formed in the ternary systems. A comparison of the stable and metastable phase diagrams of the ternary systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O shows that the supersaturated phenomenon of potassium borate tetrahydrate is significant and easier to appear the metastable behavior.

Li, Dong-chan; Yuan, Jun-sheng; Wang, Shi-qiang

2014-01-01

216

The relationship of KCl- and prostaglandin F2 alpha-mediated increases in tension of the porcine coronary artery with changes in intracellular Ca2+ measured with fura-2.  

PubMed Central

1. Changes in intracellular free Ca2+ concentration ([Ca2+]i) were measured simultaneously with changes in muscle tension by use of the fluorescent Ca2+ indicator, fura-2, in coronary arterial rings of the pig. 2. Changes in [Ca2+]i were measured by monitoring the ratio of fluorescence due to excitation at 340 nm (F340) to that at 380 nm (F380). 3. Increases in tension of the porcine coronary artery induced by prostaglandin F2 alpha (PGF2 alpha) (2-30 microM) and KCl (25-70 mM) were accompanied by increases in the F340/F380 fluorescence ratio of fura-2. 4. KCl-induced increases in muscle tension, equivalent to those produced by PGF2 alpha, were observed to occur in the presence of a higher [Ca2+]i. 5. Nearly complete relaxation of KCl-induced contractions by sodium nitroprusside (SNP) was accompanied by only a partial reversal of the increase in [Ca2+]i that occurred during contraction. 6. Complete relaxation of the PGF2 alpha-contracted coronary artery by cromakalim (BRL 34915) was accompanied by a nearly complete reversal of the increase in [Ca2+]i caused by the contractile agent. 7. The contractile state of smooth muscle is not an indicator of [Ca2+]i. The [Ca2+]i-tension relationship is dependent upon the type of pharmacological agent that is used to change muscle tension. PMID:1797304

Balwierczak, J. L.

1991-01-01

217

Effect of Chemical Stabilization by Phosphate Amendment on the Desorption of P and Pb From a Contaminated Soil  

E-print Network

contaminated soil treated with H3PO4 synthetic hydroxyapatite (HA), and HCl + K3PO4 was investigated using. Ranking of amendments based on total P desorbed was HCl + K3PO4 > H3PO4 > HA > untreated soil, while the reverse ranking was observed for total Pb desorption. For HCl + K3PO4- and H3PO4-amended soil, P

Sparks, Donald L.

218

I-NERI ANNUAL TECHNICAL PROGRESS REPORT: 2006-002-K, Separation of Fission Products from Molten LiCl-KCl Salt Used for Electrorefining of Metal Fuels  

SciTech Connect

An attractive alternative to the once-through disposal of electrorefiner salt is to selectively remove the active fission products from the salt and recycle the salt back to the electrorefiner (ER). This would allow salt reuse for some number of cycles before ultimate disposal of the salt in a ceramic waste form. Reuse of ER salt would, thus, greatly reduce the volume of ceramic waste produced during the pyroprocessing of spent nuclear fuel. This final portion of the joint I-NERI research project is to demonstrate the separation of fission products from molten ER salt by two methods previously selected during phase two (FY-08) of this project. The two methods selected were salt/zeolite contacting and rare-earth fission product precipitation by oxygen bubbling. The ER salt used in these tests came from the Mark-IV electrorefiner used to anodically dissolved driver fuel from the EBR-II reactor on the INL site. The tests were performed using the Hot Fuel Dissolution Apparatus (HFDA) located in the main cell of the Hot Fuels Examination Facility (HFEF) at the Materials and Fuels complex on the INL site. Results from these tests were evaluated during a joint meeting of KAERI and INL investigators to provide recommendations as to the future direction of fission product removal from electrorefiner salt that accumulate during spent fuel treatment. Additionally, work continued on kinetic measurements of surrogate quaternary salt systems to provide fundamental kinetics on the ion exchange system and to expand the equilibrium model system developed during the first two phases of this project. The specific objectives of the FY09 I-NERI research activities at the INL include the following: • Perform demonstration tests of the selected KAERI precipitation and INL salt/zeolite contacting processes for fission product removal using radioactive, fission product loaded ER salt • Continue kinetic studies of the quaternary Cs/Sr-LiCl-KCl system to determine the rate of ion exchange during the salt/zeolite contacting process • Compare the adsorption models to experimentally obtained, ER salt results • Evaluate results obtained from the oxygen precipitation and salt/zeolite ion exchange studies to determine the best processes for selective fission-product removal from electrorefiner salt.

S. Frank

2009-09-01

219

Burn rates of TiH2/KClO4/Viton and output testing of NASA SKD26100098-301 pressure cartridges  

NASA Technical Reports Server (NTRS)

The burn rates of the pyrotechnic TiH2/KClO4/Viton with a mass ratio of 30/65/5 have been measured as a function of pressure in nitrogen up to 312 MPa(45 Kpsi). The burn rates were fit to R = a pn, with a = 2.055 cm/sec/MPan and n = 0.472 between 0.15 MPa (22 psi) and 21.6 MPa (3.13 Kpsi) and a = 4.38 cm/sec/MPan and n = 0.266 between 70 MPa (10.15 Kpsi) and 312 MPa (45.25 Kpsi). The decrease in slope at the higher pressures is attributed to a diffusion limited reaction. No acoustically driven flame instabilities or large conductive-to-convective burn transitions were observed. Solid reaction products were analyzed by x-ray diffraction and scanning electron microscopy (SEM). X-ray diffraction detected only TiO2 and KC1. SEM showed that the particle size of the reaction products increased as the nitrogen pressure increased. There were no anomalous characteristics of the burn of this pyrotechnic that could be interpreted as a cause of the o-ring blow-by problem in the forward shear bolt assembly. Three NASA SKD26100098-301 pressure cartridges were fired into a fixed volume vessel that was sealed with an O-ring. A maximum pressure of 181.7 MPa(26,350 psi) was reached in around 100 ,mu sec for two shots fired into a volume of 16.3 cm3(0.996 in3). A maximum pressure of 33,460 psi was reached for one shot fired into a volume of 9.55 cm3(0.583 in3). The O-ring burned through on one shot in the larger volume and leaked on the other two thereby simulating the effects of an O-ring leak. The results imply that the piston in the shear bolt assembly would receive a large impulse even if there was a leak in an O-ring seal.

Holy, John A.

1993-01-01

220

Dilong prevents the high-KCl cardioplegic solution administration-induced apoptosis in H9c2 cardiomyoblast cells mediated by MEK.  

PubMed

Infusion of high-KCl cardioplegic solution (High-KCS) is the most common method used to induce asystole before cardiac surgery. However, our previous study showed the High-KCS can cause the apoptosis of cardiomyocytes in patients who were administered High-KCS prior to undergoing coronary artery bypass graft (CABG) to treat coronary artery disease (CAD). Therefore, it is urgent today to find a complementary medicine to reduce this damage. Dilong (earthworm) has been used as a traditional medicine in China for several thousand years, and extract from the dilong has been empirically used in Asia for the treatment of vascular disorders. In this study, we applied dilong extract to reduce myocardial cell damage from High-KCS infusion and further investigated the mechanisms. H9c2 cardiomyoblast cells were cultured in serum-free medium for 4 h and then treated with dilong at 31.25, 62.5, 125, and 250 mg/mL for 24 h, which was then followed by High-KCS treatment for 3 h to detect the protective mechanisms of dilong behind cardiomyocyte apoptosis and cardiac fibrosis. Cells were harvested for MTT assay, TUNEL assay, and western blot analysis. We found that High-KCS-induced cardiomyocyte apoptosis, enhanced the protein level of pro-apoptotic Bad, released cytochrome c, and activated caspase-3 in H9c2 cells. The IGF-I/IGF-IR/ERK pathway involved in non-cardiomyocyte proliferation, and the expression/activation of uPA, Sp-1 and CTGF, which are implicated in the development of cardiac fibrosis were up-regulated, but the Akt for cardiomyocyte survival was greatly deactivated in postcardioplegic H9c2 cardiomyoblast cells. However, dilong was highly protective and totally reversed the apoptosis and cardiac fibrosis effects induced by High-KCS. Chemical inhibitors P38 (SB203580), JNK (SP600125), MEK (U0126), IGF-1 (AG1024), and PI3K (LY294002) were applied to investigate which is the mediator for dilong attenuated High-KCS stimulated caspase 3 activation. MEK (U0126) inhibitor completely blocked dilong inhibited caspase 3 activation in High-KCS treated H9c2 cells. The MEK siRNA was further applied to knockdown MEK to confirm our finding. We found dilong worked through MEK to inhibit caspase 3 activity induced by High-KCS in H9c2 cells. Furthermore, we used the pure component of dilong, Lumbrokinase, to block the High-KCS effect. Using the microscope to observe the cell viability, we found Lumbrokinase could reverse the High-KCS effect. Lumbrokinase could also reduce the protein levels of caspase 8, caspase 9, and caspase 3, and enhance the survival related proteins PI3K/Akt and Bcl2. These results demonstrate that dilong could be used as a potential agent to block the side effects caused by High-KCS in CABG surgery patients. PMID:25482676

Han, Chien-Kuo; Kuo, Wei-Wen; Shen, Chia-Yao; Chen, Tung-Sheng; Pai, Peiying; Tsai, Chang-Hai; Lo, Feng-Yueh; Ju, Da-Tong; Huang, Chih-Yang

2014-01-01

221

LABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture  

E-print Network

to semi-automatic volumetric analysis and potentiometric titrations. Phosphoric Acid, H3PO4 (pK1= 2.16, pLABORATORY EXPERIMENT 4 Alkalimetric Titration of an Acid Mixture In this experiment triprotic acid (H3PO4) will be determined by pH- potentiometric methods. This experiment will introduce you

Nazarenko, Alexander

222

QUARTERLY PROGRESS REPORT October 1, 2001 -December 31, 2001  

E-print Network

is more effective for Pb immobilization than phosphate rock alone 6. H3PO4 synchro-acidification of soluble P relative to pre-acidification and post- acidification 7. The 2:1 ratio of PR:H3PO4 is best

Ma, Lena

223

Phosphate-induced metal immobilization in a contaminated site Rocky X. Caoa  

E-print Network

Phosphate-induced metal immobilization in a contaminated site Rocky X. Caoa , Lena Q. Maa, *, Ming Received 15 April 2002; accepted 11 July 2002 ``Capsule'': A mixture of H3PO4 and phosphate rock Florida. Phosphate was applied at a P/Pb molar ratio of 4.0 with three treatments: 100% of P from H3PO4

Ma, Lena

224

The effect of NaCl substitution with KCl on Akawi cheese: chemical composition, proteolysis, angiotensin-converting enzyme-inhibitory activity, probiotic survival, texture profile, and sensory properties.  

PubMed

The effect of partial substitution of NaCl with KCl on Akawi cheese with probiotic bacteria was investigated during 30 d of storage at 4 °C. Chemical composition, the survival of probiotic and lactic acid bacteria, proteolytic activity, and texture profile analysis were analyzed and sensory analysis was carried out to determine the effects of substitution. No significant differences were observed in moisture, protein, fat, and ash contents among the experimental Akawi cheeses at the same storage period. Significant differences were observed in water-soluble nitrogen and phosphotungstic-soluble nitrogen between experimental cheeses at the same of storage period. No significant difference was observed in the growth of Lactobacillus delbrueckii ssp. bulgaricus between experimental cheeses at the same storage period. However, the growth of Streptococcus thermophilus, Lactobacillus casei, and Lactobacillus acidophilus was significantly affected among experimental cheeses. A significant difference was observed in soluble Ca among experimental cheeses at the same storage period. In general, no significant differences existed in hardness and adhesiveness among experimental cheeses at the same storage period. No significant differences existed in sensory attributes, including creaminess, bitterness, saltiness, sour-acid, and vinegar taste among experimental Akawi cheeses at the same storage period. PMID:22916878

Ayyash, M M; Sherkat, F; Shah, N P

2012-09-01

225

Influence of partial replacement of NaCl with KCl, CaCl2 and MgCl2 on lipolysis and lipid oxidation in dry-cured ham.  

PubMed

Sodium intake above nutritional recommendations may involve harmful consequences to health such as the increased risk of cardiovascular diseases. Dry-cured ham constitutes a product with a relatively large amount of sodium. Thus, to obtain a healthier product for consumers with reduced sodium content, two formulations containing KCl alone (formulation II) or mixed with CaCl2 and MgCl2 (formulation III) have been proposed to partially replace NaCl. Lipolysis and lipid oxidation occurring in hams processed with these formulations have been studied since they have direct influence on the final flavor. No significant differences in acid lipase activity or lipid oxidation were found at the end of the process between the alternative formulations and formulation I (control with 100% NaCl). Differences in some free fatty acids, generated along the processing, were detected among treatments and at the end of dry-curing. Data suggests a slight trend towards a major lipolysis during treatment III. PMID:21531513

Ripollés, Susana; Campagnol, Paulo Cezar Bastianello; Armenteros, Mónica; Aristoy, M Concepción; Toldrá, Fidel

2011-09-01

226

LIDAR nleasurenlents of \\vind turbine wake Ineanderi ng J)l'j',lillllL'nl ul \\kcl1~lI1i('al Engineering. Fluid \\kchanic~. \\ills Koppcls /l.ik. DTU-I)uildll1,lC ..jil3.ll'llJ:1il':i1  

E-print Network

LIDAR nleasurenlents of \\vind turbine wake Ineanderi ng J)l'j',lillllL'nl ul \\kcl1~lI1iW wind turbine [1]. The wake dynamics was resol\\cd using a LIDAR based wind speed scanning system. Recent is locatcd inside a small wind Lmn cOllsi:,ting of 7 x 2 MW wind turbines. The LIDAR will be mounted

227

Internal friction in KCl single crystals  

Microsoft Academic Search

It is shown that line tension, phonon damping and charge-cloud interactions all contribute to amplitude-independent mechanical damping, while depinning and charge-cloud stretching both contribute to amplitude dependence. A theory is developed for the complete model, specifically recognizing that, following depinning, repinning does not occur later in the stress cycle. The ultrasonic composite oscillator technique is used to measure mechanical damping

M. Tanibayashi; J. L. Tallon

1986-01-01

228

Effect of the ZrCl4 concentration in the (NaCl-KCl)eqiv-UO2Cl2-ZrCl4 melt and the electrolysis current density on the quantitative composition of UO2-ZrO2 cathode deposits. Calculation and experiment  

NASA Astrophysics Data System (ADS)

A method is proposed for calculating the ZrO2 content in the (NaCl-KCl)eqiv-UO2Cl2-ZrCl4 melt. Based on the known composition of a UO2-ZrO2 cathode deposit, the content is calculated at current densities of 0.08-0.63 A/cm2 and ZrCl4 concentrations of 0-12.3 wt %. The calculated and experimental ZrO2 contents in UO2-ZrO2 cathode deposits are in qualitative and adequate quantitative agreement.

Krotov, V. E.; Filatov, E. C.

2014-08-01

229

An Experimental Study of Magnetite Solubility as a Function of Pressure Along the Dewpoint Curve in the NaCl-, KCl-, HCl-H2O-Melt System.  

NASA Astrophysics Data System (ADS)

Magnetite (Mt) is a ubiquitous phase in magmatic-hydrothermal ore deposits and, thus, any model which aims to predict the evolving physical chemistry of porphyry-ore deposit environments must incorporate data on the equilibria that control the precipitation of Mt in such systems. Extant experimental data indicate that Mt solubility is controlled via the equilibrium Fe3O4Mt + 6HClV + H2V = 3FeCl2V + 4H2OV (Chou and Eugster, 1977, AJS, p 1296); however their experiments were performed at T=500-650° C by equilibrating Mt with a HCl-bearing supercritical aqueous fluid (NaCl-, KCl-free). Conversely, data from some natural Fe-bearing fluid inclusions have evinced that initial temperatures of magmatic volatile phases (MVP) in magmatic-hydrothermal environments may exceed 800° C, possibly even approaching 900° C, in the presence of melt (Clark and Arancibia, 1995, Giant Ore Deposits-II Conference, p. 511). Thus, there currently are no data constraining Mt solubility in the high-temperature regime obtained in natural magmatic systems. Additionally, there are no data on Mt solubility as a function of changes in the chemistry of the MVP. In the system NaCl-H2O, the composition and, thus, the density of brine-saturated vapor change significantly as a function of pressure along a given isotherm and the components KCl and HCl act to shift the limbs of the solvii (Bodnar et al., 1985, GCA, p 1861; Anderko and Pitzer, 1993, GCA, p 1657; Shinohara and Fujimoto, 1994, GCA, p 4857). The absence of data constraining Mt solubility as a function of pressure along a given isotherm, the resultant change in composition and density, as well as deviations in the Na:K:H ratio of the MVP hinder the development of forward models of magmatic-hydrothermal systems. In order to provide these critical data constraining Mt solubility in geologically reasonable magmatic systems we have performed a set of experiments as a function of pressure in the vapor-only field near the 800° C isotherm in the NaCl-H2O system. Natural Mt (aFe3O4 ~1), a synthetic haplogranitic minimum melt (100 MPa) and an aqueous phase (molar K:Na:H=1) were reacted in Au capsules in rapid-quench Stellite-25 vessels, using water as the pressure medium, at 800° C, log fO2 controlled by the NNO buffer, pressures of 100 and 120 MPa, and aqueous salinities of 1.8 and 3.0 wt. % NaCl equivalent, respectively. In all experiments the mass ratio of Mt:melt:fluid was 1:1:4. Detailed petrographic examination of run products did not reveal the presence of brine inclusions; however, fluid inclusions do contain opaque phases. Using the newly determined mFeCl2 (0.0345 at 100 MPa and 0.0359 at 120 MPa) and mHCl (0.0769 at 100 MPa and 0.0947 at 120 MPa) in the quenched MVP and the known fugacities of H2O (? =1) and H2 (? =1) at P and T, apparent equilibrium constants were calculated as log K' = (CFeCl2)3 \\times (fH2O)4 \\div (CHCl)6 \\times fH2. The values of log K' are 1.605 at 100 MPa and 13.01 at 120 MPa. K is fixed for a given P and T except for the effect of activity coefficients for HCl and FeCl2. The values of log K obtained in this study will facilitate more detailed characterization of the chemistry of magmatic-hydrothermal MVPs; both fossil MVPs and those that obtain in modern geothermal reservoirs. Determination of P, T, fH2 and mFeCl2 in fluid inclusions will allow for the direct calculation of a model HCl concentration in the MVP.

Simon, A. C.

2001-12-01

230

Porous, Biphasic CaCO3-Calcium Phosphate Biomedical Cement Scaffolds from Calcite (CaCO3) Powder  

E-print Network

mixed, for 80­90 s, with an orthophosphoric acid (H3PO4) solution, which was partially neutralized to p, and implanting the bioactive bone substitute material on a patient-specific base, in real time in the surgery

Tas, A. Cuneyt

231

Rayon-based activated carbon fibers treated with both alkali metal salt and Lewis acid  

Microsoft Academic Search

Rayon precursors marinated by mixture aqueous solution containing NaCl and H3PO4 are activated by steam for manufacture of activated carbon fibers (ACF) in this work. It is interesting to find that mesopores (2nm50nm) are greatly developed on ACF surface, which indicates that NaCl+H3PO4 aqueous solution is an effectual pore size-enlarging impregnant. The influences of

Yuhan Chen; Qilin Wu; Pan Ning; Gong Jinghua; Pan Ding

2008-01-01

232

Influence of the organic solvents on the properties of the phosphoric acid dopant emulsion deposited on multicrystalline silicon wafers  

Microsoft Academic Search

This study is devoted to the formation of an n+p emitter for multicrystalline silicon (mc-Si) solar cells for photovoltaic (PV) application. The atomization technique has been used to make the emitter from H3PO4 phosphoric acid as a doping source. The doping emulsion has been optimized using several organic solvents. H3PO4 was mixed with one of these solutions: ethanol, 2-butanol, isopropanol

D. Bouhafs; A. Moussi; M. Boumaour; S. E. K. Abaïdia; L. Mahiou; A. Messaoud

2007-01-01

233

Modification of surface pretreatment of white spot lesions to improve the safety and efficacy of resin infiltration  

PubMed Central

Objective A low-viscosity resin (infiltrant) was used to inhibit the progression of white spot lesions (WSLs) and resolve associated esthetic issues. An alternative pretreatment was explored to increase the pore volume of the surface layer of the WSLs. Also, the penetration effects of the infiltrant were evaluated for various pretreatments. Methods Sixty two artificial lesions were fabricated on bovine teeth. As a positive control, 15% HCl gel was applied for 120 seconds. Further, 37% H3PO4 gel was applied for 30 seconds using three methods. The samples were divided as follows: H3PO4 only group, H3PO4 sponge group, and H3PO4 brush group. The acid was gently rubbed with the applicators (i.e., a sponge or brush) throughout the application time. To compare the effects of resin infiltration, twenty paired halves of specimens were treated with an infiltrant (ICON®). Results Thicknesses of the removed surface layers and infiltrated areas were evaluated by confocal laser scanning microscope. The positive control and the 37% H3PO4 brush group failed to show significant differences in the removed thickness (p > 0.05); however, the mean percentage of the infiltrated area was higher in the 37% H3PO4 brush group (84.13 ± 7.58%) than the positive control (63.51 ± 7.62%, p < 0.001). Scanning electron microscope observations indicate higher pore volumes for the 37% H3PO4 brush group than for the positive control. Conclusions Application of 37% H3PO4 with a brush for 30 seconds increased the pore volume of WSL surface layers and the percentage of infiltrated areas in comparison to the use of 15% HCl for 120 seconds. PMID:25133134

Yim, Hyun-Kyung; Min, Ji-Hyun; Kwon, Ho-Keun

2014-01-01

234

Effects of operating factors on the particle size distribution and particle shape of synthesized precipitated CaCO 3: effect of reaction temperature, blowing rate of CO 2 gas and initial slurry concentration of Ca(OH) 2 on reaction completion time  

Microsoft Academic Search

This study was carried out to investigate the mechanism and effects of experimental factors on the particle size distribution and particle morphology of synthesized precipitated CaCO3 in the carbonation process in which CaCO3 is formed by blowing rate of CO2 gas into lime milk. The changes of pH and temperature occurred during the carbonation process for determining the dependence of

So Yoon Park; Woo Sik Choi

2004-01-01

235

Nanotube Array  

NASA Astrophysics Data System (ADS)

A TiO2 nanotube array was grown electrochemically by using single and mixed electrolyte/s with 20 V constant potential at room temperature. Anodization was carried out for 120 min using five different electrolytes, e.g., H3PO4, NH4F, HF, NH4F with H3PO4 and HF with H3PO4. Structural characterizations of the grown titania nanotubes were conducted by using x-ray diffraction and field emission scanning electron microscopy. Optical properties of the grown nanotubes were investigated through photoluminescence (PL) spectroscopy. In the case of the 4 M H3PO4 electrolyte, no perceptible growth of nanotubes was observed. The individual electrolytes of 0.3 M NH4F and 1 M HF resulted into the formation of the wall-connected nanotubes. In contrast, the mixed electrolytes comprising the strong (NH4F, HF) and weak (H3PO4) electrolytes have been found to be efficient for the growth of wall-separated titania nanotubes. The results of the PL spectroscopy have demonstrated that the free-standing nanotubes offer low PL intensity compared to its connected counterpart owing to the lower carrier recombination rate of free-standing nanotubes.

Hazra, A.; Dutta, K.; Bhowmik, B.; Manjuladevi, V.; Gupta, R. K.; Chattopadhyay, P. P.; Bhattacharyya, P.

2014-09-01

236

High-temperature proton-exchange-membrane fuel cells using an ether-containing polybenzimidazole membrane as electrolyte.  

PubMed

Herein, poly[2,2'-(p-oxydiphenylene)-5,5'-benzimidazole] (PBI) is synthesized from 3,3'-diaminobenzidine and 4,4'-oxybisbenzoic acid, and the membrane is prepared by solvent casting. The main characteristics of PBI are studied. In the preparation of the PBI/H(3) PO(4) composite membrane, the absorbing temperature of H(3) PO(4) is 120?°C, which leads to a membrane with a high content of H(3) PO(4) . Membrane electrode assemblies (MEAs) are fabricated from PBI/H(3) PO(4) membranes with the catalyst layer made of Pt/C, PBI, and polyvinylidene fluoride (230:12:7 w/w). The fabricated MEA is tested at 150?°C with dry hydrogen and oxygen gas at 0.2 MPa for both anode and cathode feeds. No degradation of voltage is seen during stability testing of the PBI/H(3) PO(4) membrane at a constant current for 100 h. The maximum power density is 1.17 W cm(-2) , and the maximum current density is 6.0 A cm(-2) with a Pt loading of 0.5 mg cm(-2) . The high performance of these membrane materials demonstrates that PBI can be regarded as an alternative membrane material for high-temperature proton-exchange-membrane fuel cells. PMID:22529063

Li, Jin; Li, Xiaojin; Zhao, Yun; Lu, Wangting; Shao, Zhigang; Yi, Baolian

2012-05-01

237

www.kcl.ac.uk/connect Main College address  

E-print Network

and College administration are based in the nearby James Clerk Maxwell Building . Students and staff alike desks located on the ground floors of both the Franklin-Wilkins and James Clerk Maxwell Buildings. #12

Applebaum, David

238

Gravity and General Relativity at KCL D C Robinson  

E-print Network

carried out at King's since the nineteenth cen- tury. James Clerk Maxwell considered, and rejected on the history of research into gravity at King's, from Maxwell until about 1980, which will focus primarily

Bushnell, Colin J.

239

Combinatorial Mathematicians based in Britain. Abdullah, M. KCL  

E-print Network

-Seraji, Najm Sussex Al-Zengana, Emad Sussex Anderson, Dr. Ian Glasgow Anthony, Prof. Martin LSE Appa, Prof. G J. QMUL Camina, Prof. Alan R. UEA Campbell, Dr. Colin M. St. Andrews Candela Pokorna, Dr. P

240

Physicochemical properties of phosphate ester from palm kernel oil  

NASA Astrophysics Data System (ADS)

The physicochemical properties of phosphate ester from palm kernel oil have been studied. The phosphate ester was synthesized via ring-opening of epoxidized palm kernel oil with phosphoric acid. The amount of phosphoric acid (H3PO4) was varied at 0, 2.5, 5.0 and 7.5 wt%. Acid values of PKO and EPKO were 1.85 and 1.87 mg KOH/g respectively. However, the acid values increased with increasing amount of H3PO4 with values of 10.62 mg KOH/g, 31.34 mg KOH/g and 110.95 mg KOH/g respectively. The hydrolysis of the EPKO has successfully converted it to PEPKO with hydroxyl value of 16.16 mg KOH/g, 26.90 and 35.33 mg KOH/g at H3PO4 of 2.5, 5.0, and 7.5wt%.

Adawiyah Norzali, Nor Rabbi'atul; Badri, Khairiah Haji; Ahmad, Ishak

2013-12-01

241

Adsorption characteristics of malachite green on activated carbon derived from rice husks produced by chemical-thermal process.  

PubMed

Phosphoric acid (H(3)PO(4)) and sodium hydroxide (NaOH) treated rice husks, followed by carbonization in a flowing nitrogen were used to study the adsorption of malachite green (MG) in aqueous solution. The effect of adsorption on contact time, concentration of MG and adsorbent dosage of the samples treated or carbonized at different temperatures were investigated. The results reveal that the optimum carbonization temperature is 500 degrees C in order to obtain adsorption capacity that is comparable to the commercial activated carbon for the husks treated by H(3)PO(4). It is interesting to note that MG adsorbed preferably on carbon-rich than on silica rich-sites. It is found that the behaviour of H(3)PO(4) treated absorbent followed both the Langmuir and Freundlich models while NaOH treated best fitted to only the Langmuir model. PMID:15978990

Rahman, I A; Saad, B; Shaidan, S; Sya Rizal, E S

2005-09-01

242

Technology development for phosphoric acid fuel cell powerplant, phase 2  

NASA Technical Reports Server (NTRS)

A technique for producing an acid inventory control member by spraying FEP onto a partially screened carbon paper backing is discussed. Theoretical analysis of the acid management indicates that the vapor composition of 103% H3PO4 is approximately 1.0 ppm P4O10. An SEM evaluation of corrosion resistance of phenolic resins and graphite/phenolic resin composites in H3PO4 at 185 C shows specific surface etching. Carbonization of graphite/phenolic bipolar plates is achieved without blistering.

Christner, L.

1979-01-01

243

EQUILIBRIUM AND KINETICS OF DISPERSE DYE ADSORPTION ON ACTIVATED CARBON PREPARED FROM RATTAN SAWDUST BY CHEMICAL ACTIVATION  

Microsoft Academic Search

The liquid-phase adsorption of C.I. Disperse Orange 30 (DO30) onto activated carbon prepared from rattan sawdust by chemical activation with H3PO4. The rattan sawdust was carbonized at 500oC, 2h and impregnated ratio weight with H3PO4 at 1:4.5. The effects of various parameters such as contact time, initial DO30 concentration and pH were investigated at temperature 30±1oC. Langmuir, Freundlich, Temkin and

A. A. AHMAD; B. H. HAMEED; A. L. AHMAD

2008-01-01

244

Investigation of the phosphoric acid -N,N-dimethylformamide system as potential solvent for cellulose  

Microsoft Academic Search

Viscosity, density, conductivity, solution and mixing enthalpies of the phosphoric acid - N,N-dimethylformamide system were measured over the whole concentration range at temperatures of 25–65°C. The conclusions on the dissociation of phosphoric acid and formation of complexes of H3PO4\\/DMF=21 in the system under investigation were performed.

J. Fadeeva; L. Shmukler; L. Safonova

2003-01-01

245

Polyvinylpyrrolidone and polyethylenimine as inhibitors for the corrosion of a low carbon steel in phosphoric acid  

Microsoft Academic Search

Polarization and weight loss studies showed that both polyvinylpyrrolidonc and polyethylenimine are effective for the inhibition of low carbon steel over a wide concentration range of aqueous phosphoric acid (H3PO4) solutions. Both polymers retard the anodic and cathodic corrosion reactions with emphasis on the former. The results for uninhibited acid confirm the kinetic expression proposed by Mathur and Vasudevan.

Y. Jianguo; W. Lin; V. Otieno-Alego; D. P. Schweinsberg

1995-01-01

246

Production of ethanol and furfural from corn stover  

Technology Transfer Automated Retrieval System (TEKTRAN)

Corn stover has potential for economical production of biofuels and value-added chemicals. The conversion of corn stover to sugars involves pretreatment and enzymatic hydrolysis. We have optimized hydrothermal, dilute H2SO4 and dilute H3PO4 pretreatments of corn stover for enzymatic saccharificati...

247

Polysaccharides isolated from sugar beet pulp by quaternization under acidic conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sugar beet pulp was extracted and chemically modified under acidic conditions using glycidyltrimethylammonium chloride in the presence of trifuoroacetic (TFA), HCl or H3PO4. The goal was to find out how the type of acid used and quaternization could affect the yield of soluble polysaccharide, its mo...

248

Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soft drink consumption may have adverse effects on BMD, but studies have shown mixed results. In addition to displacing healthier beverages, colas contain caffeine and phosphoric acid (H3PO4), which may adversely affect bone. We hypothesized that consumption of cola is associated with lower BMD. BMD...

249

USE OF VATERITE AND CALCITE IN FORMING CALCIUM PHOSPHATE CEMENT A. Cuneyt Tas  

E-print Network

scaffolds were prepared by acid-base neutralization of concentrated H3PO4 and NaOH. 0.5 M phosphate buffer for synthesizing spheroidal vaterite powders has also been developed. Setting solutions for calcite-based cement as the biomineralization phases in forming their hard tissues, due to the scarcity of dissolved phosphorus (

Tas, A. Cuneyt

250

O Isotopic Composition of CaCO3 Measured by Continuous Flow Isotope Ratio Mass Spectrometry: Statistical Evaluation and  

E-print Network

XL continuous flow isotope ratio mass spectrometer. Conditions for which the H3 PO4 ­ CaCO3 reactiond13 C and d18 O Isotopic Composition of CaCO3 Measured by Continuous Flow Isotope Ratio Mass the stable carbon and oxygen isotope ratios of small samples (400±20 µg) of calcium carbonate. This new

251

LABORATORY EXPERIMENT 7 The Iodometric Determination of Copper in Brass  

E-print Network

acid. An excess of potassium iodide is added, and the liberated iodine is titrated with standard of the complex just disappears, and then add 1 mL of 85% H3PO4. Cool to room temperature. Treat each sample

Nazarenko, Alexander

252

Analysis of Protein Phosphorylation by Hypothesis-Driven Multiple-Stage Mass  

E-print Network

using tandem mass spectrometry (MS2) in a vacuum MALDI ion trap mass spectrometer, where the neutral, such as cell cycle progression, signal transduction cascades, and gene expression.1,2 To understand,13 In tandem MS (MS2), phosphorylated peptide ions undergo preferential neutral loss of the elements H3PO4

Chait, Brian T.

253

Acid hydrolysates of acorn polysaccharides as substrates for Candida utilis growth  

Microsoft Academic Search

Summary Acorn starchy endosperm was saccharified by dilute HCZ, H2SO4 and H3PO4, and the hydrolysates were used as substrates forC. utilis growth. The effects of acid on both stages were investigated and optimized. Biomass yields up to 27.3% on acorn or 83% of theoretical value are reported.

D. Kekos; E. G. Koukios

1985-01-01

254

Enhanced xylose recovery from oil palm empty fruit bunch by efficient acid hydrolysis.  

PubMed

Oil palm empty fruit bunch (EFB) is abundantly available in Malaysia and it is a potential source of xylose for the production of high-value added products. This study aimed to optimize the hydrolysis of EFB using dilute sulfuric acid (H2SO4) and phosphoric acid (H3PO4) via response surface methodology for maximum xylose recovery. Hydrolysis was carried out in an autoclave. An optimum xylose yield of 91.2 % was obtained at 116 °C using 2.0 % (v/v) H2SO4, a solid/liquid ratio of 1:5 and a hydrolysis time of 20 min. A lower optimum xylose yield of 24.0 % was observed for dilute H3PO4 hydrolysis at 116 °C using 2.4 % (v/v) H3PO4, a solid/liquid ratio of 1:5 and a hydrolysis time of 20 min. The optimized hydrolysis conditions suggested that EFB hydrolysis by H2SO4 resulted in a higher xylose yield at a lower acid concentration as compared to H3PO4. PMID:23709290

Tan, Hooi Teng; Dykes, Gary A; Wu, Ta Yeong; Siow, Lee Fong

2013-08-01

255

Response surface optimization of corn stover pretreatment using dilute phosphoric acid for enzymatic hydrolysis and ethanol production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Dilute H3PO4 (0.0 - 2.0%, v/v) was used to pretreat corn stover (10%, w/w) for conversion to ethanol. Pretreatment conditions were optimized for temperature, acid loading, and time using a central composite design. Optimal pretreatment conditions were chosen to promote sugar yields following enzym...

256

Antimicrobial effect of calcium hydroxide as an intracanal medicament in root canal treatment: a literature review - Part I. In vitro studies  

PubMed Central

The goal of endodontic treatment is the prevention and control of pulpal and periradicular infections. Calcium hydroxide (Ca(OH)2) has been widely used in endodontics as an intracanal medicament to eliminate the remaining microorganisms after chemomechanical preparation. The purpose of this article is to review the antimicrobial properties of Ca(OH)2 as an intracanal medicament in root canal treatment. The first part of this review details the characteristics of Ca(OH)2 and summarizes the results of in vitro studies related to its antimicrobial effect. The antimicrobial effect of Ca(OH)2 results from the release of hydroxyl ions when it comes into contact with aqueous fluids. Ca(OH)2 has a wide range of antimicrobial effects against common endodontic pathogens, but is less effective against Enterococcus faecalis and Candida albicans. The addition of vehicles or other agents might contribute to the antimicrobial effect of Ca(OH)2. PMID:25383341

2014-01-01

257

A titration model for evaluating calcium hydroxide removal techniques  

PubMed Central

Objective Calcium hydroxide (Ca(OH)2) has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH)2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH)2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH)2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH)2 followed by gross Ca(OH)2 removal using hand files and randomized treatment of either: 1) Syringe irrigation; 2) Syringe irrigation with use of an apical file; 3) Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI), or 4) Syringe irrigation with apical file and PUI (n=12/group). Residual Ca(OH)2 was dissolved with glycerin and titrated to measure residual Ca(OH)2 left in the root. Results No method completely removed all residual Ca(OH)2. The addition of 30 s PUI with or without apical file use removed Ca(OH)2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH)2. The use of PUI (with or without apical file) resulted in significantly lower Ca(OH)2 residue compared to irrigation alone. PMID:25760272

PHILLIPS, Mark; McCLANAHAN, Scott; BOWLES, Walter

2015-01-01

258

Evaluation of calcium hydroxide contents in pozzolanic cement pastes by a chemical extraction method  

Microsoft Academic Search

The aim of the study is to investigate the calcium hydroxide (Ca(OH)2) contents in pozzolanic cement pastes analyzed by the chemical extraction method and thermal analysis (DTA\\/TG). The second part of the study involves the carbonation of pozzolanic cement pastes and its influence on Ca(OH)2 reduction. The Ca(OH)2 contents in cement pastes after being subjected to accelerated carbonation were investigated

Kritsada Sisomphon; Lutz Franke

2011-01-01

259

Development and Pilot Plant Evaluation of Silica Enhanced Lime Sorbents for Dry Flue Gas Desulfurization  

Microsoft Academic Search

EPA’s efforts to develop low cost, retrofitable flue gas cleaning technology include the development of highly reactive sorbents. Recent work addressing lime enhancement and testing at the bench-scale followed by evaluation of the more promising sorbents in a pilot plant are discussed here.The conversion of Ca(OH)2 with SO2 increased several-fold compared with Ca(OH)2 alone when Ca(OH)2 was slurrled with fly

Wojciech Jozewicz; Claus Jorgensen; John C. S. Chang; Charles B. Sedman; Theodore G. Brna

1988-01-01

260

Measurement of shift in K X-ray peak energies of potassium and calcium in different compounds using EDXRF  

NASA Astrophysics Data System (ADS)

Energy shifts in K X-ray peaks of potassium and calcium in different chemical compounds have been determined from their X-ray spectra recorded in an energy dispersive X-ray fluorescence (EDXRF) set-up. The set-up comprises low-power X-ray tube photon source and Si(PIN) detector (AMPTEK model XR-100 CR). A statistical procedure has been followed to determine the shifts and t-test was applied to find the statistical significance of the results. The shifts were determined in potassium compounds; KCl, KBr, KI, K2CO3, K2Cr2O7, K2CrO4, K2SO4, K3Fe(CN)6, K4Fe(CN)6, KHSO4, KMnO4 and KSCN with KNO3 as reference and in calcium compounds; Ca(NO3)2 · 4H2O, Ca(OH)2, CaCl2, CaCO3, CaSO3 and CaSO4 · 2H2O with CaO as reference and correlated with differences in electro-negativity, number of ligands, structural changes, type of bonding, axial distances, etc. in the compounds. The shifts in potassium compounds have been evaluated for the first time while the same for calcium compounds almost agree well with the earlier reported measurements in literature.

Kaur, Kamaldip; Mittal, Raj

2014-12-01

261

Chemical characterization of combustion deposits by TOF-SIMS  

NASA Astrophysics Data System (ADS)

We have investigated the potential usefulness of TOF-SIMS for chemical analysis of deposits formed in combustion reactors. By using TOF-SIMS, it was possible to (i) identify inorganic chemical compounds in the deposits, (ii) semi-quantitatively estimate the relative concentrations of the main constituents and (iii) obtain images showing the lateral distribution of the main constituents, on the surface and in cross-sections of deposit samples. It was found that the main components in the deposit samples were KCl and K 2SO 4, while K 2CO 3, NaCl, Na 2SO 4, Ca(OH) 2 and CaCl 2 were present in smaller concentrations. In addition, deposits from combustion of recycled wood chips contained considerable amounts of ZnCl 2, PbCl 2, ZnO and PbO. Large variations in the chemical composition were observed for different samples and throughout the cross-section of a single sample. The chlorides, in particular NaCl, were present mainly as particles, while the sulfates were more homogeneously distributed in the deposit. The results from this study show that TOF-SIMS analysis of combustion deposits can contribute significantly to an increased understanding of the formation and growth of deposits in combustion reactors.

Sjövall, P.; Lausmaa, J.; Tullin, C.; Högberg, J.

2003-01-01

262

By-Products Utilization  

E-print Network

paste. The hcp is composed of solids and voids. The major solids are crystals of calcium silicate hydrates (C-S-H), calcium hydroxide (Ca(OH)2), calcium sulfoaluminates (C6AS3H32), and unhydrated portland% for Ca(OH)2, and 15 to 20% for calcium sulfoaluminates of total volumes of solids in a completely

Wisconsin-Milwaukee, University of

263

Dark fermentative hydrogen production from neutralized acid hydrolysates of conifer pulp.  

PubMed

Concentrated acid hydrolysis of cellulosic material results in high dissolution yields. In this study, the neutralization step of concentrated acid hydrolysate of conifer pulp was optimized. Dry conifer pulp hydrolysis with 55 % H(2)SO(4) at 45 °C for 2 h resulted in total sugar yields of 22.3-26.2 g/L. The neutralization step was optimized for solid Ca(OH)(2), liquid Ca(OH)(2) or solid CaO, mixing time, and water supplementation. The highest hydrogen yield of 1.75 mol?H(2)/mol glucose was obtained with liquid Ca(OH)(2), while the use of solid Ca(OH)(2) or CaO inhibited hydrogen fermentation. Liquid Ca(OH)(2) removed sulfate to below 30 mg SO(4) (2-)/L. Further optimization of the neutralization conditions resulted in the yield of 2.26 mol?H(2)/mol glucose. PMID:23065404

Nissilä, Marika E; Li, Ya-Chieh; Wu, Shu-Yi; Puhakka, Jaakko A

2012-12-01

264

Laser Fired Local Back Contact C-Si Solar Cells Using Phosphoric Acid for Back Surface Field  

NASA Astrophysics Data System (ADS)

We report on a laser doping process for the formation of a local back surface field (BSF) using phosphoric acid (H3PO4) for n-type passivated emitter rear totally diffused silicon solar cells. The sheet resistance of the BSF layer was varied by changing the H3PO4 concentration. The BSF layer was passivated using SiN x . With the passivated BSF, the LBC solar cell shows an improved open circuit voltage. A laser power of 44 mW with 10 kHz resulted in a 45-?/sq BSF layer with effective lifetime of 290 ?s and a higher V oc of 623 mV. With the optimized laser parameters, devices with the best electrical results yielded a short circuit current density of 36 mA/cm2 and an efficiency of 18.26%.

Balaji, Nagarajan; Park, Cheolmin; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Chung, Sungyoun; Raja, Jayapal; Yi, Junsin

2015-04-01

265

Influence of the experimental conditions on porosity and structure of adsorbents elaborated from Moroccan oil shale of Timahdit by chemical activation.  

PubMed

This study records experiments undertaken to determine the suitable conditions for the use of the oil shale of Timahdit, as an adsorbent for water treatment. A simple process was proposed based on chemical activation. The preparation has been carried out by carbonization after impregnation of the precursor with phosphoric acid. The effect of different conditions of preparation on the specific surface area is discussed. These parameters are H3PO4/shale weight ratio, carbonization temperature, carbonization time and concentration of H3PO4. The properties and surface structure of the adsorbent were investigated by XPS and FT-IR. Their total surface acidity and basicity were also determined. The retention process of methylene blue (MB) by adsorbents has been studied. It was found that MHP2 and MHP7 have relatively high retention ability as compared to activated carbons. PMID:15721527

Ichcho, S; Khouya, E; Fakhi, S; Ezzine, M; Hannache, H; Pallier, R; Naslain, R

2005-02-14

266

Scandium separation from tungsten crucibles : preliminary investigation into the separation of scandium metal from tungsten metal crucibles using an acid soak process.  

SciTech Connect

The first step in an attempt to isolate Sco from a Wo crucible was explored by soaking the samples in a series of organic (HOAc) and inorganic (HCl, H2SO4, H3PO4, HNO3) acids. All samples, except the HOAc, yielded a powder. The weight loss suggests that HNO3 is the most efficient solvent; however, the powders were tentatively identified by PXRD and found to contain both W and Sc by-products. The higher weight loss may also indicate dissolution of the Wo crucible, which was further evidenced upon visual inspection of the crucible. The H3PO4 acid soak yielded the cleanest removal of Sc from the crucible. More work to understand the separation of the Sco from the Wo crucible is necessary but the acid routes appear to hold promise under not as of yet established criteria.

Boyle, Timothy J.; Hess, Ryan Falcone; Neville, Michael Luke; Howard, Panit Clifton

2013-02-01

267

Laser Fired Local Back Contact C-Si Solar Cells Using Phosphoric Acid for Back Surface Field  

NASA Astrophysics Data System (ADS)

We report on a laser doping process for the formation of a local back surface field (BSF) using phosphoric acid (H3PO4) for n-type passivated emitter rear totally diffused silicon solar cells. The sheet resistance of the BSF layer was varied by changing the H3PO4 concentration. The BSF layer was passivated using SiN x . With the passivated BSF, the LBC solar cell shows an improved open circuit voltage. A laser power of 44 mW with 10 kHz resulted in a 45-?/sq BSF layer with effective lifetime of 290 ?s and a higher V oc of 623 mV. With the optimized laser parameters, devices with the best electrical results yielded a short circuit current density of 36 mA/cm2 and an efficiency of 18.26%.

Balaji, Nagarajan; Park, Cheolmin; Ju, Minkyu; Lee, Seunghwan; Kim, Jungmo; Chung, Sungyoun; Raja, Jayapal; Yi, Junsin

2015-02-01

268

Effect of preparation conditions of activated carbon from bamboo waste for real textile wastewater.  

PubMed

This study deals with the use of activated carbon prepared from bamboo waste (BMAC), as an adsorbent for the removal of chemical oxygen demand (COD) and color of cotton textile mill wastewater. Bamboo waste was used to prepare activated carbon by chemical activation using phosphoric acid (H(3)PO(4)) as chemical agent. The effects of three preparation variables activation temperature, activation time and H(3)PO(4):precursor (wt%) impregnation ratio on the color and COD removal were investigated. Based on the central composite design (CCD) and quadratic models were developed to correlate the preparation variables to the color and COD. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum condition was obtained by using temperature of 556 degrees C, activation time of 2.33 h and chemical impregnation ratio of 5.24, which resulted in 93.08% of color and 73.98% of COD. PMID:19765899

Ahmad, A A; Hameed, B H

2010-01-15

269

Preparation of a novel rape pollen shell microencapsulation and its use for protein adsorption and pH-controlled release.  

PubMed

This study aims to synthesize hollow microspheres (HMS) from rape pollen via H3PO4 hydrothermal carbonization. The rape pollen hollow shell was used as the carrier and bovine serum albumin as a model protein. The properties of HMS were characterized by scanning electron microscope (SEM), solid-state nuclear magnetic resonance and elemental analysis. The SEM images clearly showed that the HMS had perfect spherical morphology and porous hollow surface. In the separated filtrate, a large number of sucroses were detected by high-performance liquid chromatography, suggesting that the hydrolysis of starch molecules occurred during the hydrothermal process. The formation of HMS was that the rape pollen inclusion was removed from rape pollen shell to preserve integral HMS by H3PO4 hydrothermal. The HMS possessed amphiphilic surfaces, which was suitable for protein adsorpion and pH-controlled release application. PMID:24963958

Ma, Hongbo; Zhang, Peiqi; Wang, Jidong; Xu, Xianju; Zhang, Hui; Zhang, Zhenhua; Zhang, Yongchun; Ning, Yunwang

2014-01-01

270

Preliminary surface analysis of etched, bleached, and normal bovine enamel  

SciTech Connect

X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness.

Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C. (Univ. of Toronto, Ontario (Canada))

1990-09-01

271

Synergistic inhibition effect of rare earth cerium(IV) ion and sodium oleate on the corrosion of cold rolled steel in phosphoric acid solution  

Microsoft Academic Search

The synergistic inhibition effect of rare earth cerium(IV) ion (Ce4+) and sodium oleate (SO) on the corrosion of cold rolled steel (CRS) in 3.0M phosphoric acid (H3PO4) has been investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM) methods. The results reveal that SO has a moderate inhibitive effect and its adsorption obeys Temkin

Xianghong Li; Shuduan Deng; Hui Fu; Guannan Mu

2010-01-01

272

Corrosion protection of NdFeB magnets by surface coatings - Part 2: Electrochemical behaviour in various solutions  

Microsoft Academic Search

Various surface modification techniques, including single and bimetallic electroplating, and chemical vapour deposition (CVD), have been applied to improve the poor corrosion resistance of NdFeB magnets. The corrosion resistance of the surface-treated samples has been compared with that of some commercially available coated samples including nickel, zinc, gold coatings. Potentiokinetic polarisation behaviour in 1N H2SO4, 10% H3PO4 and Ringer's solution

H. H. Man; H. C. Man; L. K. Leung

1996-01-01

273

The Use of Activated Carbon Prepared from Jackfruit (Artocarpus heterophyllus) Peel Waste for Methylene Blue Removal  

Microsoft Academic Search

Jackfruit peel waste which has no economic value has been utilized for activated carbon preparation. The preparation of the activated carbon was carried out using chemical activation with phosphoric acid as activating agent. The impregnation ratio was 4:1 (g H3PO4\\/g raw material) and semi carbonization process was conducted at 200oC and followed with carbonization at 550oC. The applicability of this

Devarly PRAHAS; Yoga KARTIKA; Nani INDRASWATI; Suryadi ISMADJI

274

31 P and 51 V MAS-NMR Characterisation of Mixed Vanadium and Titanium Phosphates Prepared from Molecular Precursors  

Microsoft Academic Search

Coprecipitation of mixed vanadium and titanium phosphates has been performed by reacting a mixed solution of vanadium alkoxide (VO(OPrn)3) and titanium alkoxide (Ti(OPrn)4) with anhydrous phosphoric acid (H3PO4). The goal is to obtain a mixture at a molecular level of phosphates with both acidic and redox properties. In protic solvents, such as propanol, the vanadium phosphate precipitation is slow, so,

S. A. Ennaciri; C. R’kha; P. Barboux; J. Livage; J. Maquet

2005-01-01

275

Synthesis of hydroxyapatite by using calcium carbonate and phosphoric acid in various water-ethanol solvent systems  

Microsoft Academic Search

The purpose of the present study is to synthesize hydroxyapatite by using CaCO3 and H3PO4 in various water-ethanol solvent systems. It was observed from experiments that formation of ammonium phosphate compounds\\u000a hindered the formation of calcium phosphates in ethanol medium. Although the reactivity was better in aqueous medium, the\\u000a carbonate contents of the products obtained were above 8.5%. Best results

Arzu Engin; ?smail Girgin

2009-01-01

276

USO DE DIFERENTES MATERIAS PRIMAS PARA LA PRODUCCIÓN BIOTECNOLÓGICA DE XILITOL USE OF DIFFERENT RAW MATERIALS FOR BIOTECHNOLOGICAL XYLITOL PRODUCTION USO DE DIFERENTES MATERIAS PRIMAS PARA Á PRODUCCIÓN BIOTECNOLÓXICA DE XILITOL  

Microsoft Academic Search

This work deals with the biotechnological production of xylitol from xylose of hemicellulosic hydrolysates of sugarcane bagasse, eucalyptus, rice straw and wheat straw, by the yeast Candida guilliermondii FTI 20037. The hydrolysates were evaporated under vacuum in order to achieve a xylose concentration about 100 g\\/L and then treated with CaO until pH 7.0 and H3PO4 until pH 5.5, followed

E. A. Martinez; M. L. M. Villarreal; J. B. Almeida e Silva; A. I. N. Solenzal; L. Canilha; S. I. Mussatto

2002-01-01

277

Improvement of the preparation method of “ship-in-the-bottle” type 12-molybdophosphoric acid encaged Y-type zeolite catalysts  

Microsoft Academic Search

In this work, efforts were made to improve the preparation method of “ship-in-the-bottle” type 12-molybdophosphoric acid (PMo12) encaged Y-type zeolite catalysts. First, the possibilities of modifying other popular heteropoly acid synthesis methods to prepare encaged catalysts were examined. It was found that only the conventional method, which uses MoO3 and H3PO4 for PMo12 synthesis, led to a significant amount of

Shin R Mukai; Mitsutaka Shimoda; Litsu Lin; Hajime Tamon; Takao Masuda

2003-01-01

278

The Unexpected Role of Aldehydes and Ketones in the Standard Preparation Method for Vanadium Phosphate Catalysts  

Microsoft Academic Search

VO(H2PO4)2 is formed as the exclusive product from the reaction of aldehydes or ketones with V2O5 and H3PO4 whether aqueous (85%) or crystalline (100%) orthophosphoric acid is used. This exclusive product formation has been observed with a broad range of aldehydes and ketones (C4–C10). This finding casts doubt on the current commercial preparation of vanadium phosphate catalysts used for the

Jonathan K. Bartley; Richard P. K. Wells; Graham J. Hutchings

2000-01-01

279

Adsorption characteristics of malachite green on activated carbon derived from rice husks produced by chemical–thermal process  

Microsoft Academic Search

Phosphoric acid (H3PO4) and sodium hydroxide (NaOH) treated rice husks, followed by carbonization in a flowing nitrogen were used to study the adsorption of malachite green (MG) in aqueous solution. The effect of adsorption on contact time, concentration of MG and adsorbent dosage of the samples treated or carbonized at different temperatures were investigated. The results reveal that the optimum

I. A. Rahman; B. Saad; S. Shaidan; E. S. Sya Rizal

2005-01-01

280

A microleakage study of gutta-percha/AH Plus and Resilon/Real self-etch systems after different irrigation protocols  

PubMed Central

The development and maintenance of the sealing of the root canal system is the key to the success of root canal treatment. The resin-based adhesive material has the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls. Moreover, the irrigation protocols may have an influence on the adhesiveness of resin-based sealers to root dentin. Objective The objective of the present study was to evaluate the effect of different irrigant protocols on coronal bacterial microleakage of gutta-percha/AH Plus and Resilon/Real Seal Self-etch systems. Material and Methods One hundred ninety pre-molars were used. The teeth were divided into 18 experimental groups according to the irrigation protocols and filling materials used. The protocols used were: distilled water; sodium hypochlorite (NaOCl)+eDTA; NaOCl+H3PO4; NaOCl+eDTA+chlorhexidine (CHX); NaOCl+H3PO4+CHX; CHX+eDTA; CHX+ H3PO4; CHX+eDTA+CHX and CHX+H3PO4+CHX. Gutta-percha/AH Plus or Resilon/Real Seal Se were used as root-filling materials. The coronal microleakage was evaluated for 90 days against Enterococcus faecalis. Data were statistically analyzed using Kaplan-Meier survival test, Kruskal-Wallis and Mann-Whitney tests. Results No significant difference was verified in the groups using chlorhexidine or sodium hypochlorite during the chemo-mechanical preparation followed by eDTA or phosphoric acid for smear layer removal. The same results were found for filling materials. However, the statistical analyses revealed that a final flush with 2% chlorhexidine reduced significantly the coronal microleakage. Conclusion A final flush with 2% chlorhexidine after smear layer removal reduces coronal microleakage of teeth filled with gutta-percha/AH Plus or Resilon/Real Seal SE. PMID:25025557

PRADO, Maíra; SIMÃO, Renata Antoun; GOMES, Brenda Paula Figueiredo de Almeida

2014-01-01

281

A Reduced Polyoxomolybdenum Borophosphate Anion Related to the Wells-Dawson Clusters  

E-print Network

3N2H4, H3PO4, HCl, and H2O, in the molar ratio 1:0.13:1.67:3:3.33:1:74 (pH 1.5), heated for 5 days obtained as a pure phase in nearly 80% yield. Small changes of the pH or the ratio of the reactants led anions known for molybdenum and tungsten phosphates no such borophosphate compound was reported before

282

TiO2 nanotubes: H+insertion and strong electrochromic effects  

Microsoft Academic Search

The present work studies H+ intercalation and electrochromic effects on anodic TiO2 nanotube layers. The nanotube layers were fabricated by anodization of titanium in 1 M (H3PO4) + 1 M (NaOH) + 0.5 wt% HF electrolyte at 20 V, this results in nanotubular layers with a thickness of 1 ± 0.1 ?m with individual tube diameter of 100 ± 10

Andrei Ghicov; Hiroaki Tsuchiya; Robert Hahn; Jan M. Macak; Andres G. Muñoz; Patrik Schmuki

2006-01-01

283

Agave sisalana, a biosorbent for the adsorption of Reactive Red 120 from aqueous solution  

Microsoft Academic Search

The textile industry is one of the largest producers of dye effluent. Treatment of these effluents has to be cost effective hence a number of precursors have been studied as a viable alternative adsorbent. Sisal fibre was converted to activated carbon by chemical methods. Sisal fibre was activated with different activating agents such as H3PO4, HCl, HNO3, NaOH and KOH.

Venkateshwarapuram Rengaswami Giri Dev; Jayarama Reddy Venugopal; Thamdiannan Senthil Kumar; Lima Rose Miranda; Seeram Ramakrishna

2010-01-01

284

Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration  

Microsoft Academic Search

Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H3PO4) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC

Jie Wei; Jiecheng Wang; Xiaochen Liu; Jian Ma; Changsheng Liu; Jing Fang; Shicheng Wei

2011-01-01

285

In situ soil treatments to reduce the phyto- and bioavailability of lead, zinc, and cadmium.  

PubMed

A study was established near a former Zn and Pb smelter to test the ability of soil amendments to reduce the availability of Pb, Zn, and Cd in situ. Soil collected from the field was amended in the lab with P added as 1% P-H3PO4, biosolids compost added at 10% (referred to hereafter as "compost"), and a high-Fe by-product (referred to hereafter as "Fe") + P-triple superphosphate (TSP) (2.5% Fe + 1% P-TSP) and incubated under laboratory conditions at a constant soil pH. Changes in Pb bioavailability were measured with an in vitro test and a feeding study with weanling rats. Field-amended and incubated soils using these plus additional treatments were evaluated using the in vitro extraction and tall fescue (Festuca arundinacea Schreb. cv. Kentucky-31) metal concentration. Reductions were observed across all parameters but were not consistent. In the feeding study, the 1% P-H3PO4 and compost treatments resulted in a decrease of 26% in rat tissue Pb concentration compared with the control soil. The 2.5% Fe + 1% P-TSP showed a 39% decrease. The 1% P-H3PO4 treatment caused the greatest reduction in in vitro extractable Pb from field samples (pH 2.2) with a measured reduction of 66%, while the compost treatment had a 39% reduction and the 2.5% Fe + 1% P-TSP treatment a 50% reduction. The in vitro extraction (pH 1.5) run on field samples showed no reduction in the compost or Fe treatments. The 1% P-H3PO4 treatment was the most effective at reducing plant Pb, Zn, and Cd. PMID:15074803

Brown, Sally; Chaney, Rufus; Hallfrisch, Judith; Ryan, James A; Berti, William R

2004-01-01

286

Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn;  

E-print Network

; Cu; Ag; Ti; GaAs; GaN Sulfuric Acid (H2SO4): C; Cu; GaAs; Fe; Pb; Ni; Ti Aqua Regia (3 HCl : 1 HNO3 : hydrofluoric acid (49%, aq) HNO3 : nitric acid (70%, aq) H2SO4 : sulfuric acid (96%, aq) H3PO4 : phosphoricAcetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In

Garmestani, Hamid

287

Ion-sculpting of nanopores in amorphous metals, semiconductors, and insulators  

E-print Network

of photolithography and wet etching steps, 2 milling of pores in the free-standing mem- branes using a 50 keV Ga2, the samples used were 200- nm-thick low-pressure chemical vapor deposition LPCVD grown nonstoichiometric Si was dissolved in hot H3PO4 to expose the oxide surface, prior to pore milling. The free-standing oxide membranes

288

Surface texturing of p-GaN layer for efficient GaN LED by maskless selective etching  

Microsoft Academic Search

The maskless selective wet etching of p-GaN layer with KOH in ethylene glycol (KE) and H3PO4\\/H2SO4 (HH) acids was developed for the highly efficient light-emitting diodes (LEDs). The p-GaN surfaces textured by the selective wet etching process without using etch mask showed hexagonal and stripe shapes in the KE and HH solutions, respectively. The current-voltage (I-V) characteristics of the LED

Seok-In Na; Dae-Seob Han; Seok-Soon Kim; Jae-Hong Lim; Ja-Yeon Kim; Seong-Ju Park

2005-01-01

289

Carbon-coated Fe3O4 microspheres with a porous multideck-cage structure for highly reversible lithium storage.  

PubMed

A novel H3PO4 etching strategy together with subsequent carbon coating has been developed for the synthesis of carbon-coated Fe3O4 microspheres with a porous multideck-cage structure. These carbon-coated Fe3O4 microspheres manifest high specific capacity (?1100 m h g(-1) at 200 mA g(-1)) and excellent cycling stability for lithium storage. PMID:25794361

Wang, Yanrong; Zhang, Lei; Wu, Yali; Zhong, Yijun; Hu, Yong; Lou, Xiong Wen David

2015-04-25

290

LONG-TERM RESPONSES OF THE KUPARUK RIVER ECOSYSTEM TO PHOSPHORUS FERTILIZATION  

Microsoft Academic Search

A long-term stream fertilization experiment was performed to evaluate the potential eutrophication of an arctic stream ecosystem. During 16 years of summer phos- phorus (H3PO4) fertilization, we observed a dramatic change in the community structure of the Kuparuk River on the North Slope of Alaska. A positive response to fertilization was observed at all trophic levels with increases in epilithic

K. Slavik; B. J. Peterson; L. A. Deegan; W. B. Bowden; A. E. Hershey; J. E. Hobbie

2004-01-01

291

Impact of surface characteristics of activated carbon on adsorption of BTEX  

Microsoft Academic Search

Five residues of botanical origin were tested as potential activated carbon precursors; these are: date pits (DP), cotton stalks (CS), peach stones (PS), almond shells (ALS), and olive stones (OS). A standard activation procedure was followed (impregnation with 50% H3PO4 and heat treatment at 773 K) for the sake of comparison. Texture characteristics were determined by analysis of the N2\\/77

A. A. M Daifullah; B. S Girgis

2003-01-01

292

Hydrogen\\/oxygen polymer electrolyte membrane fuel cell (PEMFC) based on acid-doped polybenzimidazole (PBI)  

Microsoft Academic Search

The potential-current characteristics of a H2\\/O2 polymer electrolyte membrane fuel cell using H2SO4 or H3PO4 doped PBI were studied for the first time. The conditions involved in the doping of PBI with sulphuric acid or phosphoric acid and the preparation of a membrane electrode assembly (MEA) using these membranes were determined. The potential-current fuel-cell characteristics of MEAs using H2SO4-doped PBI

O. Savadogo; B. Xing

293

Electrochemical Behavior of Polyaniline, Poly(o-Anisidine) and Their Copolymer Thin Films in Inorganic and Organic Supporting Electrolytes  

Microsoft Academic Search

The influence of inorganic and organic supporting electrolytes on electrochemical, optical, and conducting properties of polyaniline, poly(o-anisidine), and poly(aniline-co-o-anisidine) thin films were investigated. Homo- and copolymer thin films were synthesized electrochemically, under cyclic voltammetric conditions in aqueous solutions of inorganic acids, viz., H2SO4, HCl, HNO3, H3PO4, and HClO4 and organic acids, viz., benzoic acid, cinnamic acid, oxalic acid, malonic acid,

D. D. Borole; U. R. Kapadi; P. P. Mahulikar; D. G. Hundiwale

2005-01-01

294

Beneficial effects of phosphoric acid as an additive in the preparation of activated carbon fibers from Nomex aramid fibers by physical activation  

Microsoft Academic Search

Activated carbon fibers (ACFs) were prepared by CO2 activation of chars obtained by pyrolyzing Nomex [poly (m-phenylene isophthalamide)], either alone or pre-impregnated with phosphoric acid (impregnation ratio of 7 wt.% H3PO4). The resulting materials were characterized by elemental analysis, X-ray diffraction, SEM-EDX, thermogravimetry and N2 (77 K) and CO2 (273 K) adsorption. Nomex impregnation with phosphoric acid produced an increase

F Suárez-Garc??a; A Mart??nez-Alonso; J. M. D Tascón

2002-01-01

295

Removal of ammonia from waste air streams with clinoptilolite tuff in its natural and treated forms  

Microsoft Academic Search

Natural and impregnated clinoptilolite tuffs were studied to assess their potential to remove ammonia from air and, in a subsequent\\u000a application, to use the spent adsorbent as a fertilizer. H2SO4, H3PO4 and HNO3, as agents containing important plant nutrients compatible with soil, were selected for impregnation to enhance sorption\\u000a capacity of the natural clinoptilolite tuffs for ammonia removal. Sorbents were

Karel Ciahotný; Lenka Melenová; Hana Jirglová; Olga Pachtová; Milan Ko?i?ík; Mladen Ei?

2006-01-01

296

Simultaneous removal of acetaldehyde, ammonia and hydrogen sulphide from air by active carbon impregnated with p -aminobenzoic acid, phosphoric acid and metal compounds  

Microsoft Academic Search

Simultaneous removal of acetaldehyde, ammonia, and hydrogen sulphide from air by the impregnated active carbon was studied at 25‡C. p-Aminobenzoic acid (PABA), phosphoric acid (H3PO4), and metal compound such as copper (II) chloride dihydrate (CuCl2·2H2O), copper (II) nitrate trihydrate (Cu(NO3)2·3H2O), and potassium iodide (KI) were investigated as impregnation ingredients. Acetaldehyde and ammonia were simultaneously removed from air by the active

M. Sugiura; K. Fukumoto

1994-01-01

297

Encapsulation of strontium aluminate phosphors to enhance water resistance and luminescence  

Microsoft Academic Search

Strontium aluminate SrAl2O4:Eu2+,Dy3+ phosphors are chemically unstable against water or even moisture. To enhance the water resistance of the phosphors, an encapsulation was performed by direct surface reactions with phosphoric acid (H3PO4). The morphology, surface structure, surface element composition, water resistance, luminescence, and photoacoustic spectrum of the phosphors before and after encapsulation were discussed. Experimental results showed that phosphors were

Yong Zhu; Jianghua Zeng; Wenyu Li; Li Xu; Qiu Guan; Yingliang Liu

2009-01-01

298

Comparison of the Inhibitory Action of KCl and Guanidine Hydrochloride Solutions on Montmorillonite Swelling  

Microsoft Academic Search

This study compares the effectiveness of potassium chloride with guanidine chlorhydrate in the prevention of clay swelling. The results given on various swelling tests on calcic montmorillonite led to the conclusions that (1) guanidine chlorhydrate is more effective than potassium chloride, especially in low concentrations, and (2) water immersion of samples treated by both solutions shows the permanent feature of

M. Iltis; G. Didier; P. Lareal

1982-01-01

299

Selective Reduction of Active Metal Chlorides from Molten LiCl-KCl using Lithium Drawdown  

SciTech Connect

In support of optimizing electrorefining technology for treating spent nuclear fuel, lithium drawdown has been investigated for separating actinides from molten salt electrolyte. Drawdown reaction selectivity is a major issue that needs to be investigated, since the goal is to remove actinides while leaving the fission products in the salt. A series of lithium drawdown tests with surrogate fission product chlorides was run to obtain selectivity data with non-radioactive salts, develop a predictive model, and draw conclusions about the viability of using this process with actinide-loadd salt. Results of tests with CsCl, LaCl3, CeCl3, and NdCl3 are reported here. An equilibrium model has been formulated and fit to the experimental data. Excellent fits to the data were achieved. Based on analysis and results obtained to date, it is concluded that clean separation between minor actinides and lanthanides will be difficult to achieve using lithium drawdown.

Michael F. Simpson; Daniel LaBrier; Michael Lineberry; Tae-Sic Yoo

2012-10-01

300

Supramolecular assemblies of 1,4-benzene diboronic acid on KCl(001)  

E-print Network

by means of non-contact Atomic Force Microscopy. When depositing the molecules on the freshly cleaved the intermolecular H-bonds, while avoiding the intermolecular steric hindrance. This work is the first experimental energy, intermolecular interactions and, in most cases, planar adsorption of the tectons. The less

Boyer, Edmond

301

A study of some effects of magnetic and electric fields on LiF and KCl  

E-print Network

the Nat- ional Aeronautics and Space Administration. ACCEPTANCE PAGE ACKNONLEDGEMENTS LIST OF FIGURES Chapter I. INTRODUCTION TABLE OF CONTENTS Page II. MAGNETIC FIELD STUDIES A. Crystals B. Apparatus 1. Suspension System and Optics 2. Field... of magnetic anisotropies ~ In an ideal single crystal of an alkali halide the susceptibilities in the directions of the crystalline axes, g? and g?, would be equal and no torque would be found if the crystal were hung verti- cally along its symmetry axis...

Miller, James Edward

1966-01-01

302

Anodic dissolution of irradiated metallic fuels in LiCl-KCl melt  

NASA Astrophysics Data System (ADS)

Electrorefining is the main step in pyro-process of spent nuclear fuels, where actinides are recovered and separated from fission products. In the present study, electrorefining of irradiated metallic fuels called METAPHIX-1 (U-19 wt%Pu-10 wt%Zr alloy irradiated at PHENIX reactor, approximate maximum burn-up 2.5 at%) was performed. A major focus was on minimization of Zr co-dissolution from spent metallic fuels to reduce the burden to the pyro-process. Based on the ICP-MS analysis results and the SEM-EDX observations, the anodic dissolution behavior of the irradiated metallic fuels and the mass balances of actinides and fission products during the electrorefining were evaluated.

Murakami, T.; Kato, T.; Rodrigues, A.; Ougier, M.; Iizuka, M.; Koyama, T.; Glatz, J.-P.

2014-09-01

303

Exposure damage mechanisms for KCl windows in high power laser systems  

NASA Technical Reports Server (NTRS)

An experimental study of the 10.6 micrometer and 0.6328 micrometer optical properties of single crystal and europium doped polycrystal is described. Significant variations in the optical properties are observed over periods of exposure up to 100 hours. Models are proposed to predict the 10.6 micrometer absorptivity for long exposure periods. Mechanical creep has been detected in both materials at high temperature.

Blaszuk, P. R.; Woody, B. A.; Hulse, C. O.; Davis, J. W.; Waters, J. P.

1976-01-01

304

Time-resolved picosecond spectroscopy of the resonant secondary radiation of F centers in KCl  

NASA Astrophysics Data System (ADS)

The linear polarization (P HL) of hot luminescence (HL) composing of the resonant secondary radiation of the F centers has been measured using a time-resolved picosecond spectroscopy over the whole Stokes wavenumber ? range. The P HL holds constant value of about 40% until the onset of ordinary luminescence (OL), from where it decreases to vanishingly small with decrease of ? This implies that the optically excited F center relaxes down along the 2p-like adiabatic potential energy surface (APES) trough, and transits to the 2s-like APES trough to form the relaxed excited state (RES). The lattice relaxation time and the dynamical transition time are ultra fast estimated to be less than 15 psec.

Akiyama, N.; Nakahara, F.; Ohkura, H.

1995-12-01

305

Mutations in the K+/Cl- cotransporter gene kazachoc (kcc) increase seizure susceptibility in Drosophila  

E-print Network

CG9925 gene was responsible for the strain’s recessive BSrecessive lethal phenotypes, indicating that kcc is an essential gene.recessive eas PC80 allele carries a frameshift mutation and probably constitutes a null allele. The bss gene

Hekmat-Scafe, Daria S; Lundy, Miriam Y; Ranga, Rakhee; Tanouye, Mark A

2006-01-01

306

Advances in Environmental Monitoring and Modelling http://www.kcl.ac.uk/advances  

E-print Network

Island and Erta `Ale may have otherwise gone unreported because of their inaccessibility. Monthly MODIS, volcano monitoring, Nyamuragira, Erta `Ale, Kilauea, Howard Island 1.0 INTRODUCTION The use of satellites

Wright, Robert

307

Characteristics of microporous/mesoporous carbons prepared from rice husk under base- and acid-treated conditions.  

PubMed

The study reports the preparation of activated carbon with a high surface area from rice husk using chemical activation with H(3)PO(4) and ZnCl(2). Activated carbon prepared from rice husk usually exhibits low specific surface areas due to its high ash content. However, experimental results show that base-leaching and acid-washing processes can effectively enhance the adsorption capacity of rice-husk carbon. The study also investigates the effects of preparation parameters on the surface characteristics of the carbon. These parameters include the kind of activating agent, before and after treatment procedures, impregnation ratio and activation temperature. The chemical and physical properties of samples were examined by EA, ICP-MS, XRD, FTIR, SEM and a N(2)-adsorption meter. The surface areas obtained from ZnCl(2) and H(3)PO(4) activation are as high as 2434 and 1741 m(2)/g, respectively. These values are higher than that of activated carbon treated with neither base nor acid (1262 and 508 m(2)/g for ZnCl(2) and H(3)PO(4) activation). Thermogravimetric analysis shows that the activation process can be divided into three parts based on temperature zones. The results of this study will be useful in developing resource recovery systems for agricultural biomass. PMID:19595505

Liou, Tzong-Horng; Wu, Shao-Jung

2009-11-15

308

A novel photodiode made of hybrid organic/inorganic nanocomposite  

NASA Astrophysics Data System (ADS)

Novel hybrid organic/inorganic nanocomposites made of metal oxide and conjugated polymer nanocomposite and its application in bulk-heterojunction solar cells were studied. The composite was composed of different concentrations of strontium titanate (SrTiO3) and polyaniline doped phosphoric acid. The optimum concentration of strontium titanate was found to be 0.2 v/v. An inorganic-organic photovoltaic device with a structure of Ag/Pani-H3PO4-SrTiO3/Al has been fabricated. The ideality factor value of the diode was found to be 1.8. This n value of the diode implies a deviation from ideal junction behaviour. The barrier height phib value for the diode was found to be 0.56 eV. The Ag/Pani-H3PO4-SrTiO3/Al diode shows a photovoltaic behaviour with a maximum open-circuit voltage Voc of 2.49 V, and short-circuit current Isc of 5.6 mA under light illumination ? = 460 nm. The conversion efficiency was found to be 5.2%. It is evaluated that the Ag/Pani-H3PO4-SrTiO3/Al diode is a good photodiode with calculated electronic parameters.

Mahmoud, Waleed E.

2009-08-01

309

[Separation of drugs cephalexin, ampicillin, and their biosynthetic precursors L-Phe-L-Cys-D-Val and D-Phe-L-Cys-D-Val by capillary zone electrophoresis].  

PubMed

The separation of drugs cephalexin, ampicillin and their biosynthetic precursors L-Phe-L-Cys-D-Val and D-Phe-L-Cys-D-Val was investigated by using capillary zone electrophoresis in acidic Tris-H3PO4 buffer at pH 2.3. With 50 mmol/L Tris-H3PO4 (pH 2.3) buffer, L-Phe-L-Cys-D-Val and D-Phe-L-Cys-D-Val were only partially separated whereas near baseline separation was achieved between cephalexin and ampicillin. The experiments showed that the addition of beta-type cyclodextrins (beta-CD) to the running buffer can influence the separation selectivity. When beta-CD was used as buffer additives at 12 mmol/L, the separation between L-Phe-L-Cys-D-Val and D-Phe-L-Cys-D-Val was much improved, however, the separation between cephalexin and ampicillin was impaired. When using 50 mmol/L Tris-H3PO4 containing 12 mmol/L DM-beta-CD (pH 2.3) buffer system, all compounds investigated were completely separated. This separation method is simple, fast and easy to operate. It involves only the conventional reagents with a much lower run cost than using HPLC. It is expected to be used in the synthetic process monitoring. PMID:15739483

Wang, Z; Sun, Y; Wang, D

1997-09-01

310

Microscopic cleanliness evaluation of the apical root canal after using calcium hydroxide mixed with chlorhexidine, propylene glycol, or antibiotic paste.  

PubMed

This study evaluated cleaning of the dentinal wall after removal of different calcium hydroxide pastes. Sixty-eight single-rooted teeth were prepared using the step-back technique and randomly divided into 4 groups according to medication used: Ca(OH)2 with 0.2% chlorhexidine solution (Group 1), Ca(OH)2 with propylene glycol (Group 2), Ca(OH)2 with antibiotic paste (ciprofloxacin, metronidazole) and distilled water (Group 3), and Ca(OH)2 with antibiotic paste and propylene glycol (Group 4). The samples were stored at 37 °C and 100% relative humidity for 21 days. The medicaments were removed using 5 mL 1% NaOCl, instrumentation with master apical file, 5 mL 1% NaOCl, patency with the K-file #10, ultrasonic instrumentation, and 10 mL 17% EDTA-T. The specimens were analyzed using scanning electron microscopy and chemical analysis. The Kruskal-Wallis (? = 5%) test showed that were no differences between the experimental groups when comparing Ca(OH)2 removal (P = .0951). The chi-square test (? = 5%) indicated a predominance of Ca(OH)2 obstructing dental tubules in all groups. On the basis of the methodology applied, it was concluded that the apical dentine surface remained equally covered by Ca(OH)2, regardless of the vehicle used. PMID:21168349

da Silva, Juliana M; Andrade Junior, Carlos V; Zaia, Alexandre A; Pessoa, Oscar F

2011-02-01

311

Activation and reactivity of novel calcium-based sorbents for dry SO2 control in boilers (journal article)  

Microsoft Academic Search

Chemically modified Ca(OH)2 sorbents for SO2 control in utility boilers were tested in an electrically heated, bench-scale isothermal flow reactor, operated at between 700 and 1000 C and residence times of from 0.6 to 2 sec calculated from bulk gas flowrates. Novel surfactant-modified Ca(OH)2 (SM-Ca(OH)2) sorbents were compared to conventional Ca(OH)2 produced by dry hydration (DH-Ca(OH)2). Sorbents were activated in

W. Jozewicz; D. A. Kirchgessner

1989-01-01

312

Host-finding behavior of Strongyloides stercoralis infective larvae to sodium cation, human serum, and sweat.  

PubMed

The host-finding behavior of Strongyloides stercoralis infective larvae was examined by in vitro agarose assay method. As human body fluid contains 0.85% (ca 0.15 molar) NaCl, various concentrations of sodium chloride, from 0.5M to 0.01M (7 steps), were examined. Many larvae were attracted at concentrations between 0.5 and 0.05M of sodium chloride. The concentration of 0.05M attracted the most larvae. The concentration of 0.02M of sodium chloride showed greatly reduced larval attraction compared with 0.05M. Therefore, the threshold concentration was determined as 0.05M. Then, 0.05M of chemicals were examined in a further experiment. Chloride compounds (NaCl, KCl, CaCl2, MgCl2) were investigated. These chemicals are components of human body fluids. Distilled water was used as the control in all experiments. Only sodium chloride attracted the larvae. Next, alkaline compounds were examined [NaOH, KOH, Ca(OH)2, and Mg(OH)2]. Larvae accumulated only at the NaOH site. The results suggested that the Na cation is important for larval attraction. A high pH value did not influence attraction at all. Next, human serum was tested. The human serum used was from normal serum to 1:32 diluted sera by distilled water (7 steps). Hierarchical attraction was seen according to serum concentration. Next, human sweat was collected from a limited zone of chest skin where only eccrine glands were distributed. Non-diluted sweat attracted the most larvae. Sweat might act as one of the most probable factors for infection by this skin-penetrating nematode. PMID:16438188

Koga, Masataka; Nuamtanong, Supaporn; Dekumyoy, Paron; Yoonuan, Tippayarat; Maipanich, Wanna; Rojekittikhun, Wichit; Waikagul, Jitra

2005-01-01

313

Preparation of ultrafine calcium carbonate particles with micropore dispersion method  

Microsoft Academic Search

Ultrafine particles of CaCO3 were synthesized by dispersing the mixture of CO2 and N2 into the Ca(OH)2\\/H2O slurry with a micropore-plate. Because the micropore is micrometers scale, process of momentum transfer, mass transfer and reaction was significantly enhanced. The carbonation process of Ca(OH)2\\/H2O system was monitored with pH and conductivity. Operation conditions were investigated on the specific surface area of

Guohua Wu; Yujun Wang; Shenlin Zhu; Jiading Wang

2007-01-01

314

Effects of alkalis, oxidants and urea on the nutritive value of rhodes grass ( Chloris gayana cv. Callide)  

Microsoft Academic Search

Two in sacco experiments were conducted to evaluate the impact on the nutritive value of rhodes grass hay (Chloris gayana cv. Callide) of treatment with alkalis or oxidants. In Experiment 1, three alkalis (Ca(OH)2, NaOH, CaO) and two oxidants (NaOCl and H2O2) were applied at levels of 0, 20, 40, 60 or 80g\\/kg of dry matter (DM). NaOH, Ca(OH)2 and

B. C Granzin; G. McL Dryden

2003-01-01

315

Sonochemical Formation of CaCO3 Nanoparticles with Controlled Particle Size Distribution  

Microsoft Academic Search

The effect of operating parameters such as flow rate of CO2 and concentration of Ca(OH)2 on the particle size distribution, crystallite size, and induction period of nano calcium carbonate synthesis in a sonochemical carbonization process has been investigated. Synthesis of calcium carbonate was carried out by bubbling CO2 gas (40, 50, 60 L\\/h) through Ca(OH)2 slurry (4%, 5%, 6% by

S. H. Sonawane; C. V. Kapadnis; Satish Meshram; S. P. Gumfekar; P. K. Khanna

2010-01-01

316

The experimental investigation of concrete carbonation depth  

Microsoft Academic Search

Phenolphthalein indicator has traditionally been used to determine the depth of carbonation in concrete. This investigation uses the thermalgravimetric analysis (TGA) method, which tests the concentration distribution of Ca(OH)2 and CaCO3, while the X-ray diffraction analysis (XRDA) tests the intensity distribution of Ca(OH)2 and CaCO3. The Fourier transformation infrared spectroscopy (FTIR) test method detects the presence of C–O in concrete

Cheng-Feng Chang; Jing-Wen Chen

2006-01-01

317

Partial Replacement of Portland Cement with Fly Ashes and Kiln Dusts Using Supercritical Carbon Dioxide Processing  

Microsoft Academic Search

The natural curing reactions which occur in a standard portland cement involve the formation of portlandite, Ca(OH)2, and calcium silicate hydrates, CSH. Over time, a cured cement absorbs carbon dioxide (CO2) from the air, converting the portlandite and some of the CSH to calcium carbonate, CaCO3. Although this carbonation reaction is thermodynamic ally-favorable, the conversion of Ca(OH)2 to CaCO3 results

James B. Rubin; Craig M. V. Taylor

318

Zentrum fur Technomathematik  

Microsoft Academic Search

Abstract. The reaction CO2 + Ca(OH)2 ! H2O + CaCO3 takes place in unsaturated porous concrete-based materials with separated reactants, where CO2 and H2O are diusing,and Ca(OH) 2 can be assumed as immobile. The process (called carbonation) plays an important,role in the service life of concrete-based structures. Our aims are threefold: (1) We study via a matched-asymptotics approach the occurrence

Adrian Muntean; Michael Bohm

2006-01-01

319

Preparation of nanoparticles with a semi-batch gas–liquid membrane contactor  

Microsoft Academic Search

Nanosized calcium carbonate particles were prepared with a semi-batch gas–liquid membrane contactor. A mathematical model of the semi-batch operated contactor was given, and the effects of Ca(OH)2 concentration, CO2 partial pressure and additives on the absorption rate were estimated theoretically. The predicted data were consistent with the experimental results. The Ca(OH)2 concentration and CO2 pressure have no apparent effects on

Zhiqian Jia; Qing Chang; Aynur Mamat

2011-01-01

320

Effect of the addition of calcium hydroxide on the hydrothermal-mechanochemical treatment of Eucalyptus.  

PubMed

The effect of Ca(OH)2 addition on optimization of hydrothermal-mechanochemical pretreatment, which combines hydrothermal and milling treatments, was examined. The highest glucose yield of 90% was achieved in the ball-milled specimen previously treated at 170°C in the presence of 20% Ca(OH)2 per substrate weight. The specific surface area of the substrate was closely correlated with glucose yield, and a larger specific surface area was obtained when treating the specimen at 170°C in the presence of Ca(OH)2 compared to treatment at 170°C without Ca(OH)2. Although the Ca(OH)2-treated specimen was relatively unaffected by delignification, the cleavage of the ester bonds between lignin and hemicellulose was confirmed by FT-IR. This suggests that Ca(OH)2 weakens the substrate structure by loosening the bonds between lignin and hemicellulose as the mechanism to increase the specific surface area regardless of the high lignin content, facilitating the fibrillation of fibers with mechanical milling. PMID:25496951

Ishiguro, Maki; Endo, Takashi

2015-02-01

321

Alkali-treated konjac glucomannan film as a novel wound dressing.  

PubMed

To investigate the potential medical application of konjac glucomannan (KGM), we treated KGM film with potassium hydroxide (KOH) or calcium hydroxide (Ca(OH)2), and evaluated its use as a wound dressing. The Ca(OH)2-treated KGM (Ca(OH)2-KGM) film exhibited more favorable properties of swelling, tensile strength, and elongation compared with the KOH-treated KGM (KOH-KGM) film, and also had a suitable water vapor transmission rate. Results from in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay further indicated the biocompatibility of the Ca(OH)2-KGM film with L929 fibroblast cells and HaCaT keratinocyte cells. The Ca(OH)2-KGM film inhibited the absorption and activation of platelets, and effectively promoted wound contractility in vivo, particularly at an early healing stage. Histological examination revealed considerably collagen secretion and advanced development of granulation tissue and epithelial coverage by Days 7 and 14 postsurgery in wounds treated with Ca(OH)2-KGM film. Our study results indicate the potential use of alkali-treated KGM film as a novel wound dressing. PMID:25498700

Huang, Yi-Cheng; Chu, Hao-Wen; Huang, Chih-Ching; Wu, Wen-Ching; Tsai, Jenn-Shou

2015-03-01

322

CRYOSCOPY OF THE LiCl-KCl EUTECTIC MELT CONTAINING ALKALI HALIDES AND ALKALI TITANIUM FLUORIDES AS SOLUTES  

Microsoft Academic Search

The cryoscopic behavior of NaCl, LiF, NaF, KF, LiâTiFâ, Na\\/; sub 2\\/TiFâ, and KâTiFâ in the LiCl--KC l eutectic melt is ; reported. In the regions of dilute concentrations. the behavior of the alkali ; halides is in accord with complete dissociation, the deviations from ; thermodynamic ideality being attributed to solid solution formation, and for LiF, ; in addition,

G. J. Janz; C. Solomons; H. J. Gardner; J. Goodkin; C. T. Brown

1958-01-01

323

Activation of 5-HT2A receptors upregulates the function of the neuronal K-Cl cotransporter KCC2  

PubMed Central

In healthy adults, activation of ?-aminobutyric acid (GABA)A and glycine receptors inhibits neurons as a result of low intracellular chloride concentration ([Cl–]i), which is maintained by the potassium-chloride cotransporter KCC2. A reduction of KCC2 expression or function is implicated in the pathogenesis of several neurological disorders, including spasticity and chronic pain following spinal cord injury (SCI). Given the critical role of KCC2 in regulating the strength and robustness of inhibition, identifying tools that may increase KCC2 function and, hence, restore endogenous inhibition in pathological conditions is of particular importance. We show that activation of 5-hydroxytryptamine (5-HT) type 2A receptors to serotonin hyperpolarizes the reversal potential of inhibitory postsynaptic potentials (IPSPs), EIPSP, in spinal motoneurons, increases the cell membrane expression of KCC2 and both restores endogenous inhibition and reduces spasticity after SCI in rats. Up-regulation of KCC2 function by targeting 5-HT2A receptors, therefore, has therapeutic potential in the treatment of neurological disorders involving altered chloride homeostasis. However, these receptors have been implicated in several psychiatric disorders, and their effects on pain processing are controversial, highlighting the need to further investigate the potential systemic effects of specific 5-HT2AR agonists, such as (4-bromo-3,6-dimethoxybenzocyclobuten-1-yl)methylamine hydrobromide (TCB-2). PMID:23248270

Bos, Rémi; Sadlaoud, Karina; Boulenguez, Pascale; Buttigieg, Dorothée; Liabeuf, Sylvie; Brocard, Cécile; Haase, Georg; Bras, Hélène; Vinay, Laurent

2013-01-01

324

Temperature dependence of laser-induced fluorescence of Tb3+Tb3+ in molten LiCl-KCl eutectic  

NASA Astrophysics Data System (ADS)

Fluorescence spectra and lifetimes originated from both 5D3?7FJ and 5D4?7FJ transitions of Tb were measured using time-resolved laser fluorescence spectroscopy in order to investigate the excited state relaxation in a molten salt medium. A cross-relaxation energy transfer of 5D3?5D4 resulted in rise and decay behaviors in fluorescence signal waveforms of 5D4?7FJ transitions. The fluorescence intensity ratios of 5D4?7F5 to 5D3?7F4 decreased drastically when the temperature of molten salt increased. This result suggests that the cross-relaxation effect becomes weakened with increasing temperature. In addition, a strong increase of the 5D4 emission over the 5D3 emission was observed at high Tb concentration.

C., E.; -E., Jung | S.; | W., Bae; Cha | I., A.; Bae | Y., J.; | K., Park; Song

2011-01-01

325

Fermentable sugars recovery from lignocellulosic waste-newspaper by catalytic hydrolysis.  

PubMed

The urgent need for alternative renewable energies to supplement petroleum-based fuels and the reduction of landfill sites for disposal of solid wastes makes it increasingly attractive to produce inexpensive biofuels from the organic fraction of the municipal solid waste. Therefore, municipal waste in the form of newspaper was investigated as a potential feedstock for fermentable sugars production. Hydrolysis of newspaper by dilute phosphoric acid was carried out in autoclave Parr reactor, where reactor temperature and acid concentration were examined. Xylose concentration reached a maximum value of 14 g/100 g dry mass corresponding to a yield of 94% at the best identified conditions of 2.5 wt% H3PO4, 135 degrees C, 120 min reaction time, and at 2.5 wt% H3PO4, 150 degrees C, and 60 min reaction time. For glucose, an average yield of 26% was obtained at 2.5 wt% H3PO4, 200 degrees C, and 30 min. Furfural and 5-hydroxymethylfurfural (HMF) formation was clearly affected by reaction temperature, where the higher the temperature the higher the formation rate. The maximum furfural formed was an average of 3 g/100 g dry mass, corresponding to a yield of 28%. The kinetic study of the acid hydrolysis was also carried out using the Saeman and the two-fraction models. It was found for both models that the kinetic constants (K) depend on the acid concentration and temperature. The degradation of HMF to levulinic acid is faster than the degradation of furfural to formic acid. Also, the degradation rate is higher than the formation rate for both inhibitors when degradation is observed. PMID:24617059

Orozco, Angela M; Al-Muhtaseb, Ala'a H; Rooney, David; Walker, Gavin M; Aiouache, Farid; Ahmad, Mohammad

2013-01-01

326

Unblocking the Sink: Improved CID-Based Analysis of Phosphorylated Peptides by Enzymatic Removal of the Basic C-Terminal Residue  

NASA Astrophysics Data System (ADS)

A one-step enzymatic reaction for improving the collision-induced dissociation (CID)-based tandem mass spectrometry (MS/MS) analysis of phosphorylated peptides in an ion trap is presented. Carboxypeptidase-B (CBP-B) was used to selectively remove C-terminal arginine or lysine residues from phosphorylated tryptic/Lys-C peptides prior to their MS/MS analysis by CID with a Paul-type ion trap. Removal of this basic C-terminal residue served to limit the extent of gas-phase neutral loss of phosphoric acid (H3PO4), favoring the formation of diagnostic b and y ions as determined by an increase in both the number and relative intensities of the sequence-specific product ions. Such differential fragmentation is particularly valuable when the H3PO4 elimination is so predominant that localizing the phosphorylation site on the peptide sequence is hindered. Improvement in the quality of tandem mass spectral data generated by CID upon CBP-B treatment resulted in greater confidence both in assignment of the phosphopeptide primary sequence and for pinpointing the site of phosphorylation. Higher Mascot ion scores were also generated, combined with lower expectation values and higher delta scores for improved confidence in site assignment; Ascore values also improved. These results are rationalized in accordance with the accepted mechanisms for the elimination of H3PO4 upon low energy CID and insights into the factors dictating the observed dissociation pathways are presented. We anticipate this approach will be of utility in the MS analysis of phosphorylated peptides, especially when alternative electron-driven fragmentation techniques are not available.

Lanucara, Francesco; Chi Hoo Lee, Dave; Eyers, Claire E.

2013-12-01

327

Surface phenomena of HA\\/TiN coatings on the nanotubular-structured beta Ti–29Nb–5Zr alloy for biomaterials  

Microsoft Academic Search

Surface phenomena of HA\\/TiN coatings on the nanotubular-structured beta Ti–29Nb–5Zr alloy for biomaterials have been investigated by several experimental methods. The nanotubular structure was formed by anodizing the Ti–29Nb–5Zr alloy in 1M H3PO4 electrolytes with 1.0wt.% NaF at room temperature. Hydroxyapatite (HA)\\/titanium nitride (TiN) films were deposited on Ti–29Nb–5Zr alloy specimens using a magnetron sputtering system. The HA target was

Eun-Ju Kim; Yong-Hoon Jeong; Han-Cheol Choe; William A. Brantley

328

HPLC determination and steady-state bioavailability study of levodropropizine sustained-release tablets in dogs  

Microsoft Academic Search

A simple HPLC method using UV detection was developed and validated for the determination of levodropropizine (LDP) in dog\\u000a plasma. The sample was prepared for injection using a liquid-liquid extraction method with 1-phenypiperazine as the internal\\u000a standard. The mobile phase was methanol—diethylamine solution (0.05 M) (20?80, v\\/v, pH adjusted to 3.0 with H3PO4) with a detection wavelength of 240 nm.

Lin Yan; Tongling Li; Rongqin Zhang; Xiaohong Xu; Pengcheng Zheng

2006-01-01

329

Study on the solubility and morphology of calcium sulfate dihydrate in nitric acid and phosphoric acid aqueous medium  

Microsoft Academic Search

In order to investigate the solubility of CaSO4·2H2O at different contents of H3PO4 and HNO3 aqueous medium, a series of tests was designed for determining the solubility of CaSO4·2H2O at 25°C and 65°C in different acidic concentration solvents, the crystal morphology of the deposition solid-phase after liquid-solid equilibrium was examined by microscope, and the crystalline of the deposition solid-phase was

Xiaoxia Zheng; Hongjian Jing; Junqiang Feng; Caimei Fan; Guangyue Ding; Yunfang Wang

2010-01-01

330

10-um thin GaAs membrane manufactured by nonselective etching  

NASA Astrophysics Data System (ADS)

The aim of this paper is to determine an optimum nonselective etching solution in order to manufacture an as thin as possible, uniform and high quality GaAs membrane. Three different etching systems in various proportions of the components were analyzed. A high quality 10 micrometer thin GaAs membrane was obtained using the [1(H3PO4)]: [1(CH3OH)]: [3(H2O2)] etching solution. The micromachined GaAs membranes are manufactured to be used as support for microwave circuits as well as in high temperature sensor applications.

Mueller, Alexandru; Petrini, Ioana; Avramescu, Viorel; Iordanescu, Sergiu A.; Marcelli, Romolo; Foglietti, Vittorio; Dragoman, M.

1997-09-01

331

Solvent-free synthesis, spectral correlations and antimicrobial activities of some aryl E 2-propen-1-ones  

NASA Astrophysics Data System (ADS)

Totally 38 aryl E 2-propen-1-ones including nine substituted styryl 4-iodophenyl ketones have been synthesised using solvent-free SiO2-H3PO4 catalyzed Aldol condensation between respective methyl ketones and substituted benzaldehydes under microwave irradiation. The yields of the ketones are more than 80%. The synthesised chalcones were characterized by their analytical, physical and spectroscopic data. The spectral frequencies of synthesised substituted styryl 4-iodophenyl ketones have been correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. The antimicrobial activities of 4-iodophenyl chalcones have been studied using Bauer-Kirby method.

Sathiyamoorthi, K.; Mala, V.; Sakthinathan, S. P.; Kamalakkannan, D.; Suresh, R.; Vanangamudi, G.; Thirunarayanan, G.

2013-08-01

332

Simple and sensitive high-performance liquid chromatographic method for the determination of 1,5-benzodiazepine clobazam and its active metabolite N-desmethylclobazam in human serum and urine with application to 1,4-benzodiazepines analysis  

Microsoft Academic Search

A HPLC–UV determination of clobazam and N-desmethylclobazam in human serum and urine is presented. After simple liquid–liquid extraction with dichloromethane the compounds and an internal standard diazepam were separated on a Supelcosil LC-8-DB column at ambient temperature under isocratic conditions using the mobile phase: CH3CN–water–0.5 M KH2PO4–H3PO4 (440:540:20:0.4, v\\/v and 360:580:60:0.4, v\\/v for serum and urine, respectively). The detection was

Pawe? K Kunicki

2001-01-01

333

Analysis and confirmation of synthetic anorexics in adulterated traditional Chinese medicines by high-performance capillary electrophoresis  

Microsoft Academic Search

Six synthetic anorexics, clobenzorex, diethylpropion, fenfluramine, methamphetamine, phenylpropanolamine and phentermine, which can be found as adulterants in traditional Chinese medicines were assayed simultaneously by high-performance capillary electrophoresis. The electrolyte was a buffer solution containing 120 mM phosphate buffer (NaH2PO4\\/H3PO4, pH 2.0) and 15% acetonitrile. Applied voltage was 16 kV and temperature was 30°C. Fluoren-2,7-diammonium chloride was used as an internal

Yoe-Ray Ku; Yuan-Shiun Chang; Kuo-Ching Wen; Li-Kang Ho

1999-01-01

334

Propane fuel cells using phosphoric-acid-doped polybenzimidazole membranes.  

PubMed

Propane fuel cells using H(3)PO(4)-doped polybenzimidazole polymer membranes produce low and unsustainable current densities at temperatures up to 250 degrees C under anhydrous conditions. Stable intermediate species blocked the surface of noble metal anode catalysts, and the intermediate species could not react further into desorbable final products. In contrast, when water was introduced by light humidification (S(r) 0.08%) of the propane stream, sustainable and higher current densities were achieved. Water participated in the reaction sequence to form surface-bound hydrocarbon and then oxygen-containing intermediates and thereby generated CO and CO(2) as the only carbon-containing products. PMID:16852618

Cheng, Chin Kui; Luo, Jing Li; Chuang, Karl T; Sanger, Alan R

2005-07-01

335

Chemical synthesis of poly(lactic-co-glycolic acid)\\/hydroxyapatite composites for orthopaedic applications  

Microsoft Academic Search

Hydroxyapatite-biodegradable polymer composites were synthesized by a colloidal non-aqueous chemical precipitation technique at room temperature. The starting materials used for synthesizing hydroxyapatite (HA, Ca10(PO4)6(OH)2) were Ca(NO3)2·4H2O and H3PO4, resulting in single phase HA while poly(d,l-lactic-co-glycolic acid) (PLGA) was used as the biodegradable polymer component. The composites were prepared containing 10, 20, and 30wt.% HA in the presence of the dissolved

Sarah E. Petricca; Kacey G. Marra; Prashant N. Kumta

2006-01-01

336

Effect of Poly (Sodium 4-Styrene Sulfonate) on the Morphology of Hydroxyapatite Particles  

PubMed Central

Nanorods hydroxyapatite, (HAP) Ca10(PO4)6(OH)2 is successfully prepared by water in oil microemulsion using, CaCL2 and H3PO4 (water phase), poly(sodium 4-styrene sulfonate) (PSSS) as template and cyclohexane as oil phase. The nano-structure of the product was studied by means of X-ray diffraction (XRD), Fourier transmission infrared spectrometer (FT-IR), scanning electron microscopy (SEM), and atomic force microscope (AFM). With this system, we could synthesize nano-particles of hydroxyapatite with high crystallinity and least agglomeration. PMID:19763237

Esmaeilian Tari, Nesa; Kashani Motlagh, Mohammad Mahdi

2009-01-01

337

Electrochemical behavior of AZ91D magnesium alloy in phosphate medium—part I. Effect of pH  

Microsoft Academic Search

The influence of pH on the corrosion behavior of Mg-based AZ91D alloy was investigated in a constant composition phosphate\\u000a medium using various electrochemical techniques, complemented with surface analysis data. The studied solutions were 0.1 M\\u000a H3PO4, NaH2PO4, Na2HPO4 and Na3PO4 having pH values of 1.8, 4.5, 9.1 and 11.8, respectively. Spontaneous passivation was substantiated from monitoring the continuous\\u000a positive shift of

Fakiha El-Taib Heakal; Amany Mohammed Fekry; Mohammed Ziad Fatayerji

2009-01-01

338

Study of the properties of electromembrane systems in a steady magnetic field  

NASA Astrophysics Data System (ADS)

The paper investigates the steady magnetic field influence on the redox reaction in the red/membrane/ox system. The systems hydrazine/membrane/ KMnO_{4}+H_{3}PO_{4} and hydrazine/membrane/Fe^{3+}+sulfosalicylic acid were investigated by the method of voltammetric characteristics. The EMF (difference of potentials) is induced in crossed electric and magnetic fields. To measure EMF, besides metal (Au, Ni, Cu, Pt) electrodes, a measuring system - "a membrane with two taps" - connected to two Ag/AgCl electrodes (for comparison) was proposed. Tables 2, Figs 5, Refs 8.

Licis, J.; Dindune, A.; Shishko, A.

2003-12-01

339

Synthesis of TiO 2 using different hydrolysis catalysts and doped with Zn for efficient degradation of aqueous phase pollutants under UV light  

Microsoft Academic Search

In this work, various TiO2 and TiO2 doped with 0.1, 1.0, and 5.0 mol% of Zn were prepared by the sol–gel method varying different hydrolysis catalysts (HNO3, OHAc, H3PO4) in order to be used as photocatalysts for environmental applications. The X-ray diffraction results showed that the different\\u000a TiO2 samples have presented the anatase as main phase, However, the acid nature has

O. Vázquez-Cuchillo; A. Cruz-López; L. M. Bautista-Carrillo; A. Bautista-Hernández; L. M. Torres Martínez; S. Wohn Lee

2010-01-01

340

Ion-exchange properties of a novel layered titanium(IV) phosphate  

Microsoft Academic Search

A novel layered titanium(IV) phosphate, Ti2O2H(PO4)[(NH4)2PO4]2 (1), was synthesized in the system TiCl4-H3PO4-(NH2)2CO-H2O under mild hydrothermal conditions. The ion-exchange behavior of 1 towards alkali, alkaline earth and some divalent metal cations in individual and complex solutions was studied. It was found that, unlike other known titanium phosphates, 1 exhibits an unusually high affinity for the mercury ion, which makes it

O. A. Khainakova; A. Espina; C. Trobajo; S. A. Khainakov; J. R. García; A. I. Bortun

2002-01-01

341

Defect selective etching of GaAsyP1-y photovoltaic materials  

NASA Astrophysics Data System (ADS)

Rapid and accurate threading dislocation density (TDD) characterization of direct-gap GaAsyP1-y photovoltaic materials using molten KOH defect selective etching (DSE) is demonstrated. TDDs measured using molten KOH DSE show close agreement with those from both electron beam-induced current mapping and planar view transmission electron microscopy, provided TDD<107 cm-2. H3PO4 DSE is also demonstrated as an accurate method for characterizing TDD of GaP substrates. Taken together, the DSE methods described here enable TDD characterization over large areas (>105 ?m2) from substrate to GaAsyP1-y device layer.

Yaung, Kevin Nay; Tomasulo, Stephanie; Lang, Jordan R.; Faucher, Joseph; Lee, Minjoo Larry

2014-10-01

342

Counter-current extraction process for recovery of U(IV) from phosphoric acid using octylphenyl acid phosphate (OPAP) extractant  

Microsoft Academic Search

The extraction of U(IV) from phosphoric acid by octylphenyl acid phosphate (OPAP) in kerosene was investigated. Parameters affecting the extraction of U(IV) from phosphoric acid were investigated. The effects of H3PO4, H2SO4, H2O2, Na2CO3 and (NH4)2CO3 concentrations, phase ratio and temperature on the stripping of uranium from the organic phase were studied. Based on the bench-scale results, a continuous counter-current

A. M. I. Ali; J. A. Daoud; M. M. Zeid; H. F. Aly

2002-01-01

343

SIMULTANEOUS DETERMINATION OF LOSARTAN POTASSIUM AND HYDROCHLOROTHIAZIDE FROM TABLETS AND HUMAN SERUM BY RP-HPLC  

Microsoft Academic Search

A new, simple, precise, rapid, and accurate RP-HPLC method has been developed for the simultaneous determination of losartan potassium and hydrochlorothiazide from tablets and human serum. Chromatography was carried out on a C18 reversed-phase column using a mixture of 0.01 M KH2PO4: acetonitrile (65:35; v\\/v) adjusted to pH 3.1 with H3PO4 at a flow rate 1.0 mL\\/min.Detection was realised at

Sibel A. Özkan

2001-01-01

344

Fabrication of porous calcite using chopped nylon fiber and its evaluation using rats.  

PubMed

Although porous calcite has attracted attention as bone substitutes, limited studies have been made so far. In the present study, porous calcite block was fabricated by introducing chopped nylon fiber as porogen. Ca(OH)2 powder containing 10 wt% chopped nylon fiber was compacted at 150 MPa, and sintered to burn out the fiber and to carbonate the Ca(OH)2 under stream of 1:2 O2-CO2. Sintering of Ca(OH)2 at 750 °C or lower temperature resulted in incomplete burning out of the fiber whereas sintering at 800 °C or higher temperature resulted in the formation of CaO due to the thermal decomposition of Ca(OH)2. However, sintering at 770 °C resulted in complete burning out of the fiber and complete carbonation of Ca(OH)2 to calcite without forming CaO. Macro- and micro-porosities of the porous calcite were approximately 23 and 16 %, respectively. Diameter of the macropores was approximately 100 ?m which is suitable for bone tissue penetration. Porous calcite block fabricated by this method exhibited good tissue response when implanted in the bone defect in femur of 12-weeks-old rat. Four weeks after implantation, bone bonded on the surface of calcite. Furthermore, bone tissue penetrated interior to the macropore at 8 weeks. These results demonstrated the good potential value of porous calcite as artificial bone substitutes. PMID:25649514

Ishikawa, Kunio; Tram, Nguyen Xuan Thanh; Tsuru, Kanji; Toita, Riki

2015-02-01

345

Phosphoric acid and sodium fluoride: a novel etching combination on titanium.  

PubMed

We investigate whether a novel and inexpensive etching method, H3PO4 + NaF, on titanium could obtain both a lower hydrogen content and superior calcium phosphate deposition performance, while achieving similar surface roughness in comparison with the traditional etching method. Pure titanium samples were treated with different concentrations of H3PO4 + NaF at ambient temperature without auxiliary implementations (groups A, B and C), and were treated using the traditional method (group T). The samples were then maintained in simulated body fluid for 10 and 20 days. The surface morphology and chemistry, as well as the hydrogen content and distribution, were studied. The hydrogen content of the new groups are in the range of 31 (3.6)-86.9 (7.2) ppm, and that of group T is 287 (13.5) ppm. The amount of deposited calcium phosphates increases as the hydrogen content approaches 90 ppm; however, this trend does not apply as the hydrogen content exceeds 90 ppm. The surface roughnesses of groups A, B and C are in the range of 0.47 (0.01)-0.92 (0.05) µm. The new surface topography regularly transforms, and the surfaces with round pits exert a better effect on the deposition of calcium phosphates than the surfaces with sharp cusps. PMID:24704898

Jia, Fang; Zhou, Lei; Li, Shaobin; Lin, Xi; Wen, Binxue; Lai, Chunhua; Ding, Xianglong

2014-06-01

346

High-temperature supercapacitor with a proton-conducting metal pyrophosphate electrolyte  

PubMed Central

Expanding the range of supercapacitor operation to temperatures above 100°C is important because this would enable capacitors to operate under the severe conditions required for next-generation energy storage devices. In this study, we address this challenge by the fabrication of a solid-state supercapacitor with a proton-conducting Sn0.95Al0.05H0.05P2O7 (SAPO)-polytetrafluoroethylene (PTFE) composite electrolyte and a highly condensed H3PO4 electrode ionomer. At a temperature of 200°C, the SAPO-PTFE electrolyte exhibits a high proton conductivity of 0.02?S cm?1 and a wide withstanding voltage range of ±2?V. The H3PO4 ionomer also has good wettability with micropore-rich activated carbon, which realizes a capacitance of 210 F g?1 at 200°C. The resulting supercapacitor exhibits an energy density of 32?Wh kg?1 at 3?A g?1 and stable cyclability after 7000 cycles from room temperature to 150°C. PMID:25600936

Hibino, Takashi; Kobayashi, Kazuyo; Nagao, Masahiro; Kawasaki, Shinji

2015-01-01

347

Chemical extraction of arsenic from contaminated soil.  

PubMed

A series of batch extraction experiments were conducted using a fortified soil with different extracting solutions such as inorganic acids (hydrochloric acid (HCl), sulfuric acid (H2SO4), phosphoric acid (H3PO4), perchloric acid (HClO4), or nitric acid (HNO3)), organic acids (acetic acid (C2H4O2), citric acid (C6H8O7)) and alkaline agent (NaOH). Various concentrations were used to investigate the removal efficiency and to optimise the concentration of each extractant. In the present investigation a Kuroboku soil contaminated with arsenite (As(III)) was used as a model soil. Arsenic was extracted most efficiently by 5% H3PO4 with a maximum of more than 99% from the model soil. Sulfuric acid also showed high percentage extraction efficiency. On the other hand, C2H4O2 and oxidizing acids such as HNO3 and HClO4 showed low efficiency of As extraction compared with C6H8O7. Although, NaOH also showed higher extraction efficiencies compared with organic and oxidizing acids but mainly arsenate (As(V)) was found to be the major component. A significant fraction of the As(III) was oxidized to As(V) during mineral acid and alkaline extraction and extraction efficiency also varied with the concentration of the acid and alkali solution. PMID:16779937

Alam, G M; Tokunaga, S

2006-01-01

348

Blue luminescence in porous anodic alumina films  

NASA Astrophysics Data System (ADS)

We have investigated the luminescence property of anodic alumina membranes (AAM) with ordered nanopore arrays prepared by electrochemically anodizing aluminium in oxalic acid, sulfuric acid and phosphoric acid solutions. The photoluminescence (PL) intensity of AAM prepared in C2H2O4 is much higher than that of AAMs prepared in H2SO4 and H3PO4. The PL spectra obtained show that there are two optical centres for the AAMs prepared in H2SO4 and H3PO4, of which the first originates from the F+ centres, and the second is associated with the F centres. It is found that the oxalic impurities incorporated in the AAMs should have important influences on the optical properties of AAM prepared in C2H2O4. The blue emission band in the AAM prepared in C2H2O4 originates from the coactions of the F+ centres, the F centre and the luminescent centres transformed from oxalic impurities.

Li, Zhaojian; Huang, Kelong

2007-05-01

349

Catalytic fast pyrolysis of cellulose and biomass to produce levoglucosenone using magnetic SO4(2-)/TiO2-Fe3O4.  

PubMed

Magnetic superacid (SO4(2-)/TiO2-Fe3O4) was prepared for catalytic fast pyrolysis of cellulose and poplar wood to produce levoglucosenone (LGO). Its catalytic activity was evaluated via pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments, and compared with the non-magnetic SO4(2-)/TiO2, phosphoric acid (H3PO4) and sulfur acid (H2SO4) catalysts. Moreover, the LGO yield was quantitatively determined. The results indicated that the magnetic SO4(2-)/TiO2-Fe3O4 was effective to selectively produce LGO from both cellulose and poplar wood. Its catalytic capability was a little better than the non-magnetic SO4(2-)/TiO2 and H3PO4, and much better than the H2SO4. The maximal LGO yields from both cellulose and poplar wood were obtained at 300 °C with the feedstock/catalyst ratio of 1/1, reaching as high as 15.43 wt% from cellulose and 7.06 wt% from poplar wood, respectively. PMID:25173471

Lu, Qiang; Ye, Xiao-ning; Zhang, Zhi-bo; Dong, Chang-qing; Zhang, Ying

2014-11-01

350

Two-dimensional correlation analysis to study variation of near-infrared water absorption bands in the presence of inorganic acids  

NASA Astrophysics Data System (ADS)

Two-dimensional (2D) correlation analysis has been utilized to investigate NIR water bands perturbed by the presence of four different inorganic acids individually: HCl, H2SO4, H3PO4, and HNO3. The observed spectral variation in the 9000-7700 cm-1 range was mainly due to interaction of dissociated H3O+ and corresponding anions with the vibration of water in a hydrogen bonding network. 2D correlation analysis of NIR spectra acquired from sample solutions (concentration range: 0.2-1.0 M) showed that individual acids differently influenced water vibration. In addition, unforeseen spectral variations under the water band that were difficult to identify with corresponding raw NIR spectra were clearly observed. Based on the asynchronous correlation analysis, three underlying individual variations occurred for HCl under the 8718 cm-1 band. Only two asynchronous correlations were observed for H2SO4 and H3PO4. The 2D correlation features of HNO3 were distinctly different from those of the other three acids due to an additional spectral feature caused by direct absorption by NO3-. The dissimilar influence of the selected acids on water vibration was confirmed by NIR spectroscopy combined with 2D correlation analysis. Partial least squares (PLS) loadings from each case were compared to examine the difference in weights that were constructed to follow the corresponding concentration changes.

Chang, Kyeol; Jung, Young Mee; Chung, Hoeil

2014-07-01

351

Effect of phosphoric acid pretreatment of corncobs on the fermentability of Clostridium beijerinckii TISTR 1461 for biobutanol production.  

PubMed

Corncobs pretreated with H2SO4, HNO3, and H3PO4 were compared to evaluate the fermentation ability of Clostridium beijerinckii TISTR 1461 to produce biobutanol via acetone-butanol-ethanol (ABE) fermentation. It was found that the hydrolysate from H3PO4 pretreatment could be used as a substrate without any inhibitor removal methods. However, in terms of sugar yield, it gave the lowest total sugars in both pretreatment and enzymatic hydrolysis. Response surface methodology was applied to optimize enzymatic hydrolysis of the pretreated corncobs. The optimized conditions reduced the consumption of enzymes and hydrolysis time to 7.68 FPU/g biomass and 63.88 hr, respectively, and yielded 51.82 g/L reducing sugars. The Celluclast 1.5 L and Novozyme 188 enzyme ratio were varied to maximize the hydrolyzed sugars. The ABE fermentation, using substrate from phosphoric acid pretreatment of corncobs, with 10 g/L glucose supplementation produced 11.64 g/L of total ABE, which was close to the control experiment using synthetic medium. This study showed that corncobs pretreated with phosphoric acid could potentially be used as a substrate without using a detoxification process. PMID:24678653

Boonsombuti, Akarin; Luengnaruemitchai, Apanee; Wongkasemjit, Sujitra

2015-01-01

352

Utilization of landfill leachate parameters for pretreatment by Fenton reaction and struvite precipitation--a comparative study.  

PubMed

This paper reports results of laboratory studies on two pretreatment methods, struvite precipitation using aeration with H(3)PO(4) and Fenton oxidation. These methods utilized specific properties of the leachate: high magnesium content (172 mg L(-1)) for struvite precipitation and a high iron concentration (56 mg L(-1)) for Fenton treatment. Struvite precipitation (H(3)PO(4), 700 mg L(-1)) removed 36% of NH(3)-N and 24% of SCOD. Fenton treatment (at pH 3.5) required 650 mg L(-1) of H(2)O(2) and removed 66% of SCOD. The effect of each pretreatment on the returned activated sludge (RAS) was evaluated using respirometry. Both methods reduced the inhibitory effect of the leachate and substantially increased biokinetic parameters. The BOD(5)/SCOD ratio increased from 0.63 for raw leachate to 0.82 (struvite) and 0.88 (Fenton). Estimation of capital and operational costs of the total leachate treatment indicated that aeration with struvite precipitation, followed by biological treatment, would be the preferred option. PMID:19097692

Kochany, J; Lipczynska-Kochany, E

2009-07-15

353

Influence d'une substitution partielle du ciment par du laitier de hauts fourneaux sur la résistance des mortiers en milieu acide  

NASA Astrophysics Data System (ADS)

Le stockage de produits chimiques dans du béton présente souvent des problèmes de durabilité dus aux attaques chimiques. Inévitablement les concentrations élevées sont les plus dangereuses. Le but de notre étude est de déterminer les changements de phases qui apparaissent dans le béton lorsqu'on substitue une partie du ciment par du laitier de haut fourneaux. Les échantillons sont conservés dans des solutions acides différents anions (HCl, H{2}SO{4}, H{3}PO{4} et CH{3}COOH) et différentes concentrations (0,1; 0,25 et 0,5M). Les formations qui apparaissent sont déterminées par diffraction X et observées au MEB. Les solutions sulfatiques conduisent à une formation de gypse en surface et d'ettringite au contact de la matrice cimentaire. Avec l'acide acétique, il y a formation de calcium acétate hydrate sous forme spongieuse tandis que, avec l'acide phosphatique, la formation de calcium hydrogeno phosphate hydrate est très superficielle. Enfin, avec l'acide chlorhydrique, la surface du mortier est recouverte de chlorure de calcium dihydrate et d'hydroxyde de fer. Les résistances mécaniques sont plus ou moins affectées par la concentration mais aussi et surtout par la nature des acides avec dans l'ordre le plus agressif H{2}SO{4} puis HCl et CH{3}COOH enfin peu de modification pour H{3}PO{4}.

Achoura, D.; Lanos, Ch.; Jauberthie, R.; Redjel, B.

2004-11-01

354

A novel controllable synthesis of silica nanotube arrays with ultraviolet photoluminescence  

NASA Astrophysics Data System (ADS)

The synthesis of large-scale one-dimensional silica nanotube (SNT) arrays embedded in Si substrate is demonstrated by using the combination of AAO template mask and Ar ion milling technique. The geometry of the SNTs could be precisely controlled by the process parameters, which included that the SNT diameter and the interpore distance were controlled by AAO anodization voltage and H 3PO 4 pore widening time, while the length of SNT was controlled by ion milling time and AAO aspect ratio. Also, the SNT fabrication parameters could be related to their photoluminescence (PL) emitting properties, when anodized at 40 V, pore widening in H 3PO 4 acid for 70 min and ion milled for 5 min, a strong intensity and stable ultraviolet (UV) light of 3.25 eV (381 nm) emitted from the SNTs under the excitation of 266 nm laser, which could be assumed arising from twofold coordinated silicon lone pair centers in the oxygen deficiency SNTs. The present fabrication of SNT arrays presents a novel method for intensity and frequency adjustable ultraviolet optoelectronic devices.

Hu, Mingzhe; Liu, Yinglin; Gu, Haoshuang; Yu, Rong; MacManus-Driscoll, Judith L.; Robinson, Adam P.

2009-07-01

355

Printed all-solid flexible microsupercapacitors: towards the general route for high energy storage devices  

NASA Astrophysics Data System (ADS)

A novel method for fabricating all-solid flexible microsupercapacitors (MSCs) was proposed and developed by utilizing screen printing technology. A typical printed MSC is composed of a printed Ag electrode, MnO2/onion-like carbon (MnO2/OLC) as active material and a polyvinyl alcohol:H3PO4 (PVA:H3PO4) as solid electrolyte. A capacity of 7.04 mF cm-2 was achieved for the screen printed MnO2/OLC MSCs at a current density of 20 ?A cm-2. It also showed an excellent cycling stability, with 80% retention of the specific capacity after 1000 cycles. The printed all-solid flexible MSCs exhibited remarkably high mechanical flexibility when the devices were bent to a radius of 3.5 mm. In addition, all-solid MSCs were successfully demonstrated by screen printing technique on various substrates, such as silicon, glass and conventional printing paper. Moreover, the screen printing technique can be extended to other active materials, such as OLC and carbon nanotubes. This method provides a general route for printable all-solid flexible MSCs, which is compatible with the roll-to-roll process for various high performance active materials.

Wang, Ye; Shi, Yumeng; Zhao, Cheng Xi; Wong, Jen It; Sun, Xiao Wei; Yang, Hui Ying

2014-03-01

356

A composite membrane of caesium salt of heteropolyacids/quaternary Diazabicyclo-octane polysulfone with poly (tetrafluoroethylene) for intermediate temperature fuel cells.  

PubMed

Inorganic-organic composite electrolyte membranes were fabricated from CsXH3-XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting by using a relatively low phosphoric acid loading, which benefits the stability of the membrane conductivity and the mechanical strength. The casting method was used in order to build a thin and robust composite membrane. The resulting composite membrane films were characterised in terms of the elemental composition, membrane structure and morphology by EDX, FTIR and SEM. The proton conductivity of the membrane was 0.04 S cm-1 with a H3PO4 loading level of 1.8 PRU (amount of H3PO4 per repeat unit of polymer QDPSU). The fuel cell performance with the membrane gave a peak power density of 240 mW cm-2 at 150 °C and atmospheric pressure. PMID:24958287

Xu, Chenxi; Wang, Xu; Wu, Xu; Cao, Yuancheng; Scott, Keith

2012-01-01

357

Enhancement of the fuel cell performance of a high temperature proton exchange membrane fuel cell running with titanium composite polybenzimidazole-based membranes  

NASA Astrophysics Data System (ADS)

The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm-2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 m? cm2 h-1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs.

Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Pinar, F. Javier

2011-10-01

358

Ab initio modeling of proton transfer in phosphoric acid clusters.  

PubMed

Development of superior electrolytes for fuel cells that enable operation at temperatures above 120 degrees C without external humidification will benefit from molecular-level understanding of proton conduction mechanisms in neat acid systems possessing little or no water. The energetics and collective molecular effects associated with proton transfer in clusters consisting of two to six phosphoric acid (H3PO4) molecules are examined with electronic structure calculations. Global minimum-energy structures are determined at the B3LYP/6-311G** level for each cluster from many chemically rational initial configurations. Binding energies are computed and found to correlate with the number and type of hydrogen bonds present in the cluster and show an increase in the strength of the interactions up to and including (H3PO4)6. This suggests that more than six molecules may be required to fully encompass the binding in bulk phosphoric acid. Potential energy profiles and associated energetic penalties for proton transfer are determined at the B3LYP/6-31G** level under four different constraints on the positions of surrounding atoms. The endothermicities decrease with increasing cluster size, suggesting that several molecules facilitate proton transfer. Calculation of partial atomic charges with the CHELPG scheme both prior to and following proton transfer indicates a higher degree of charge delocalization in the larger clusters and thereby a smaller energetic penalty. PMID:19569665

Vilciauskas, Linas; Paddison, Stephen J; Kreuer, Klaus-Dieter

2009-08-13

359

Influence of phosphate anion adsorption on the kinetics of oxygen electroreduction on low index Pt(hkl) single crystals.  

PubMed

The detrimental effects of phosphate anion adsorption on the oxygen reduction reactions (ORR) on low index Pt single crystal electrodes were studied in 0.1 M perchloric acid by using a hanging meniscus rotating disk electrode in the presence of varied concentrations of H(3)PO(4). The kinetic current for ORR decreased dramatically on Pt(100), Pt(110), Pt(111), and PtSn(111) even with the addition of a small amount (1 mM) of H(3)PO(4) into the perchloric acid solution, most probably due to the adsorption of phosphate anions onto the Pt active sites that impeded the electroreduction of O(2). Remarkably, the extent of decline was found to vary with the specific single crystal surface, following the order of Pt(111) > PtSn(111) > Pt(110) ? Pt(100). Consistent behaviors were also observed in Tafel analysis and in electrochemical impedance spectroscopic measurements. Within the present experimental context, Pt(110) was found to be the optimal crystal surface for ORR in phosphoric acid fuel cells with the smallest charge transfer resistance, whereas the poisoning effects of phosphate anion adsorption were the most pronounced on Pt(111), most likely because the phosphate anions primarily adsorbed on the 3-fold sites on the Pt(111) faces, as manifested in in situ X-ray absorption spectroscopic measurements. PMID:20725683

He, Qinggang; Yang, Xiaofang; Chen, Wei; Mukerjee, Sanjeev; Koel, Bruce; Chen, Shaowei

2010-10-21

360

Anhydrous Proton-Conducting Polymers  

NASA Astrophysics Data System (ADS)

Anhydrous proton-conducting polymers usually consist of a more or less inert polymer matrix that is swollen with an appropriate proton solvent (in most cases, phosphoric acid). An outline of the different materials is provided, with a focus on PBI/H3PO4 blends that are currently most suitable for fuel cell applications. Also discussed are alternative concepts for fully polymeric materials, which establish proton conductivity as an intrinsic property using amphoteric heterocycles such as imidazole as a proton solvent. The development of some of the first polymers is described, and the fundamental relations between their material properties and conductivity are discussed. Closely related to this relatively new concept are mechanistic investigations focusing on intermolecular proton transfer and diffusion of (protonated) solvent molecules, the contributions of both transport processes to conductivity, and the dependence of these ratios on composition, charge carrier density, etc. Although the development of fully polymeric proton conductors is inseparably related to mechanistic considerations, relatively little attention has been paid to these concepts in the field of conventional membranes (hydrated ionomers, H3PO4-based materials). Consequently, their general relevance is emphasized, and according investigations are summarized to provide a more comprehensive picture of proton transport processes within proton exchange membranes.

Schuster, Martin F. H.; Meyer, Wolfgang H.

2003-08-01

361

Aripiprazole salts IV. Anionic plus solvato networks defining molecular conformation  

NASA Astrophysics Data System (ADS)

Five new examples of aripiprazole (arip) salts are presented, viz., the Harip phthalate [Harip+·C8H5O4-(I)], homophthalate [Harip+·C9H7O4-(II)] and thiosalicilate [Harip+·C7H4O2S-(III)] salts on one side, and two different dihidrogenphosphates, Harip+·H2PO4-·2(H3PO4)·H2O (IV) and Harip+·H2PO4-·H3PO4(V). Regarding the internal structure of the aripH+ cations, they do not differ from the already known moieties in bond distances and angles, while interesting differences in conformation can be observed, setting them apart in two groups: those in I, II and III present similar conformations to those in the so far reported arip salts presenting the same centrosymmetric R(8)22 dimeric synthon, but different to those in IV and V. In parallel, the anion (+ acid) groups define bulky systems of different dimensionality (1D in the former group, 2D in the latter). The correlation between arip molecular conformation and anionic network type is discussed. An interesting feature arises with the water solvato molecule in IV, disordered around an inversion center, in regard with its interaction with an (also disordered) phosphato O-H, in a way that an “orderly disordered” H-bonding scheme arises, complying with the S.G. symmetry requirements only on average.

Freire, Eleonora; Polla, Griselda; Baggio, Ricardo

2014-06-01

362

Effect of the Basic Residue on the Energetics and Dynamics of Dissociation of Phosphopeptides  

SciTech Connect

Time- and collision-energy-resolved surface-induced dissociation (SID) of protonated peptides containing phosphoserine (s) was studied using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer configured for SID experiments. We examined fragmentation of three singly protonated peptides: GGGsGGG, KGGsGGG, and RGGsGGG. Fragmentation of GGGsGGG occurs under the mobile proton condition, while the ionizing proton is sequestered by the basic residue, resulting in the nonmobile proton condition in dissociation of the two basic peptides: KGGsGGG and RGGsGGG. RRKM modeling of the experimental data demonstrates that the energetics and dynamics of H3PO4 loss are different under mobile and nonmobile proton conditions. Specifically, fragmentation of GGGsGGG is characterized by a higher dissociation barrier, 1.68 eV, and higher activation entropy, 11 e.u. (e.u. = entropy unit), than fragmentation of the basic peptides. Similar threshold energies of 1.36 eV and 1.40 eV and activation entropies of -4.9 e.u. and 0.3 e.u. were obtained for KGGsGGG and RGGsGGG, respectively. We propose that the loss of H3PO4 from phosphoserine is a two-step process, in which the phosphate abstraction from the phosphorylated side chain is followed by dissociation of the ion-molecule complex.

Laskin, Julia; Kong, Ricky; Song, Tao; Chu, Ivan K.

2012-12-15

363

Repetitive injection field-amplified sample stacking for cationic compounds determination.  

PubMed

The development of a field-amplified sample stacking technique is presented. Sensitivity enhancement in this technique was obtained by repetitive injections of a sample followed by steps of sample matrix removal through the application of counter-pressure. Under optimized conditions the background electrolyte (BGE) was composed of 80 mM H3PO4 while the sample matrix contained 0.5mM H3PO4 and 30% (v/v) methanol. The elaborated method enabled a 4-fold effective injection of the sample (53 s, 0.5 psi). Each injection was followed by a focusing step during which the application of a voltage (2 kV) and counter-pressure (-1 psi) was performed for 0.65 min. The method was developed for the determination of six psychiatric drugs (opipramol, hydroxyzine, promazine, amitriptyline, fluoxetine, and thioridazine). The elaborated method was applied for analysis of human urine samples after a simple liquid-liquid extraction procedure. The detection limits obtained were in the range of 2.23-6.21 ng/mL. PMID:24840407

Dziomba, Szymon; Biernacki, Micha?; Ol?dzka, Ilona; Skrzydlewska, El?bieta; B?czek, Tomasz; Kowalski, Piotr

2014-07-01

364

High-temperature supercapacitor with a proton-conducting metal pyrophosphate electrolyte  

NASA Astrophysics Data System (ADS)

Expanding the range of supercapacitor operation to temperatures above 100°C is important because this would enable capacitors to operate under the severe conditions required for next-generation energy storage devices. In this study, we address this challenge by the fabrication of a solid-state supercapacitor with a proton-conducting Sn0.95Al0.05H0.05P2O7 (SAPO)-polytetrafluoroethylene (PTFE) composite electrolyte and a highly condensed H3PO4 electrode ionomer. At a temperature of 200°C, the SAPO-PTFE electrolyte exhibits a high proton conductivity of 0.02 S cm-1 and a wide withstanding voltage range of +/-2 V. The H3PO4 ionomer also has good wettability with micropore-rich activated carbon, which realizes a capacitance of 210 F g-1 at 200°C. The resulting supercapacitor exhibits an energy density of 32 Wh kg-1 at 3 A g-1 and stable cyclability after 7000 cycles from room temperature to 150°C.

Hibino, Takashi; Kobayashi, Kazuyo; Nagao, Masahiro; Kawasaki, Shinji

2015-01-01

365

A Composite Membrane of Caesium Salt of Heteropolyacids/Quaternary Diazabicyclo-Octane Polysulfone with Poly (Tetrafluoroethylene) for Intermediate Temperature Fuel Cells  

PubMed Central

Inorganic-organic composite electrolyte membranes were fabricated from CsXH3?XPMo12O40 (CsPOMo) and quaternary diazabicyclo-octane polysulfone (QDPSU) using a polytetrafluoroethylene (PTFE) porous matrix for the application of intermediate temperature fuel cells. The CsPOMo/QDPSU/PTFE composite membrane was made proton conducting by using a relatively low phosphoric acid loading, which benefits the stability of the membrane conductivity and the mechanical strength. The casting method was used in order to build a thin and robust composite membrane. The resulting composite membrane films were characterised in terms of the elemental composition, membrane structure and morphology by EDX, FTIR and SEM. The proton conductivity of the membrane was 0.04 S cm?1 with a H3PO4 loading level of 1.8 PRU (amount of H3PO4 per repeat unit of polymer QDPSU). The fuel cell performance with the membrane gave a peak power density of 240 mW cm?2 at 150 °C and atmospheric pressure. PMID:24958287

Xu, Chenxi; Wang, Xu; Wu, Xu; Cao, Yuancheng; Scott, Keith

2012-01-01

366

All-solid-state reduced graphene oxide supercapacitor with large volumetric capacitance and ultralong stability prepared by electrophoretic deposition method.  

PubMed

Portable energy storage devices have gained special attention due to the growing demand for portable electronics. Herein, an all-solid-state supercapacitor is successfully fabricated based on a poly(vinyl alcohol)-H3PO4 (PVA-H3PO4) polymer electrolyte and a reduced graphene oxide (RGO) membrane electrode prepared by electrophoretic deposition (EPD). The RGO electrode fabricated by EPD contains an in-plane layer-by-layer alignment and a moderate porosity that accommodate the electrolyte ions. The all-solid-state RGO supercapacitor is thoroughly tested to give high specific volumetric capacitance (108 F cm(-3)) and excellent energy and power densities (7.5 Wh cm(-3) and 2.9 W cm(-3), respectively). In addition, the all-solid-state RGO supercapacitor exhibits an ultralong lifetime for as long as 180 days (335?000 cycles), which is an ultrahigh cycling capability for a solid-state supercapacitor. The RGO is also tested for being used as a transparent supercapacitor electrode demonstrating its possible use in various transparent optoelectronic devices. Due to the facile scale-up capability of the EPD process and RGO dispersion, the developed all-solid-state supercapacitor is highly applicable to large-area portable energy storage devices. PMID:25545033

Wang, Mei; Duong, Le Dai; Mai, Nguyen Thi; Kim, Sanghoon; Kim, Youngjun; Seo, Heewon; Kim, Ye Chan; Jang, Woojin; Lee, Youngkwan; Suhr, Jonghwan; Nam, Jae-Do

2015-01-21

367

The adsorption of chromium (VI) from industrial wastewater by acid and base-activated lignocellulosic residues.  

PubMed

This study deals with the adsorption of Cr(VI) from synthetic and industrial wastewater, produced by a sewage plant. The activated carbons were prepared from a lignocellulosic raw material by thermal treatment at 450 and 650 degrees C in the presence of acid (AlCl(3), HCl, H(3)PO(4) and H(2)SO(4)) and base (NaOH) agents. To optimize the adsorption of Cr(VI), the chemical modifications caused by each activating agent (related to the capability of Cr(VI) removal), and the optimal experimental conditions of the pH, Cr(VI) concentration, adsorbent dose and residence time, were studied. Thus, treatment with H(3)PO(4) gives rise to carbons with a high surface area and high efficiency for Cr(VI) removal at short equilibrium times. In contrast, the generation of active surface sites by means of NaOH requires longer equilibrium times, the adsorption being less effective than in the former case. The adsorption isotherms obey the Langmuir equation only in the first stages of the reaction but fit the Freundlich equations over the whole range studied, so the heat of adsorption can be easily calculated. The results also show that the activated carbons obtained can be recovered by filtration with an efficiency of 30% in the third cycle. PMID:17126488

Alvarez, Patricia; Blanco, Clara; Granda, Marcos

2007-06-01

368

Noninvasive in situ visualization of supported catalyst preparations using multinuclear magnetic resonance imaging.  

PubMed

Multinuclear magnetic resonance imaging (MRI) is employed as a new noninvasive tool for monitoring supported catalyst preparation by visualizing precursor transport within the porous support. In particular, liquid phase 31P MRI experiments were used to visualize the dynamics of H3PO4 penetration into an alumina pellet and have revealed a strong interaction of H3PO4 with the support. Solid state 31P MRI was applied to map the distribution of the adsorbed phosphate inside the support after its drying. Comparison of the liquid phase and solid phase MRI results confirms the correlation of the phosphate distribution in the liquid phase during impregnation and the phosphate adsorbed on the support. The possibility to monitor the transport of metal atoms within the support by a direct detection of their NMR signal is demonstrated for 195Pt nucleus during impregnation of an alumina pellet with an aqueous solution of H2PtCl6. Other possible strategies for the utilization of MRI to characterize in situ the preparation of supported catalysts and other supported materials are briefly discussed. PMID:16117511

Lysova, Anna A; Koptyug, Igor V; Sagdeev, Renad Z; Parmon, Valentin N; Bergwerff, Jaap A; Weckhuysen, Bert M

2005-08-31

369

Optimization of the Alkaline Pretreatment of Rice Straw for Enhanced Methane Yield  

PubMed Central

The lime pretreatment process for rice straw was optimized to enhance the biodegradation performance and increase biogas yield. The optimization was implemented using response surface methodology (RSM) and Box-Behnken experimental design. The effects of biodegradation, as well as the interactive effects of Ca(OH)2 concentration, pretreatment time, and inoculum amount on biogas improvement, were investigated. Rice straw compounds, such as lignin, cellulose, and hemicellulose, were significantly degraded with increasing Ca(OH)2 concentration. The optimal conditions for the use of pretreated rice straw in anaerobic digestion were 9.81% Ca(OH)2 (w/w TS), 5.89?d treatment time, and 45.12% inoculum content, which resulted in a methane yield of 225.3?mL/g VS. A determination coefficient (R2) of 96% was obtained, indicating that the model used to predict the anabolic digestion process shows a favorable fit with the experimental parameters. PMID:23509824

Song, Zilin; Yang, Gaihe; Han, Xinhui; Feng, Yongzhong; Ren, Guangxin

2013-01-01

370

Alcohol dispersions of calcium hydroxide nanoparticles for stone conservation.  

PubMed

Alcohol dispersions of Ca(OH)2 nanoparticles, the so-called nanolimes, are emerging as an effective conservation material for the consolidation of stone, mortars, and plasters present in old masonry and/or mural paintings. To better understand how this treatment operates, to optimize its performance and broaden its applications, here we study the nano and microstructural characteristics, carbonation behavior, and consolidation efficacy of colloidal alcohol dispersions of Ca(OH)2 nanoparticles produced by both homogeneous (commercial nanolime) and heterogeneous phase synthesis (aged slaked lime and carbide lime putties). We observe that the alcohol not only provides a high colloidal stability to Ca(OH)2 particles, but also affects the kinetics of carbonation and CaCO3 polymorph selection. This is due to the pseudomorphic replacement of Ca(OH)2 particles by calcium alkoxides upon reaction with ethanol or 2-propanol. The extent of this replacement reaction depends on Ca(OH)2 size and time. Hydrolysis of alkoxides speeds up the carbonation process and increases the CaCO3 yield. The higher degree of transformation into calcium alkoxide of both the commercial nanolime and the carbide lime fosters metastable vaterite formation, while calcite precipitation is promoted upon carbonation of the aged slaked lime due its lower reactivity, which limits calcium alkoxide formation. A higher consolidation efficacy in terms of strength gain of treated porous stone is achieved in the latter case, despite the fact that the carbonation is much faster and reaches a higher yield in the former ones. Formation of alkoxides, which has been neglected in previous studies, needs to be considered when applying nanolime treatments. These results show that the use Ca(OH)2 nanoparticle dispersions prepared with either aged slaked lime or carbide lime putties is an economical and effective conservation alternative to commercial nanolimes produced by homogeneous phase synthesis. Ultimately, this study contributes to show that nanotechnology can help saving the built and sculptural heritage. PMID:23919634

Rodriguez-Navarro, Carlos; Suzuki, Amelia; Ruiz-Agudo, Encarnacion

2013-09-10

371

Titanium subhydride potassium perchlorate (TiH1.65/KClO4) burn rates from hybrid closed bomb-strand burner experiments.  

SciTech Connect

A hybrid closed bomb-strand burner is used to measure the burning behavior of the titanium subhydride potassium perchlorate pyrotechnic with an equivalent hydrogen concentration of 1.65. This experimental facility allows for simultaneous measurement of the closed bomb pressure rise and pyrotechnic burn rate as detected by electrical break wires over a range of pressures. Strands were formed by pressing the pyrotechnic powders to bulk densities between 60% and 90% theoretical maximum density. The burn rate dependance on initial density and vessel pressure are measured. At all initial strand densities, the burn is observed to transition from conductive to convective burning within the strand. The measured vessel pressure history is further analyzed following the closed bomb analysis methods developed for solid propellants.

Cooper, Marcia A.; Oliver, Michael S.

2012-08-01

372

Varying effects of calcium on the oxidation of palmitate and alpha-ketoglutarate in isolated rat liver mitochondria incubated in KCl-based and sucrose-based media.  

PubMed

Isolated mitochondria from rat liver were incubated in the presence of [U-14C]palmitate, ATP, CoA, carnitine, EGTA (ethylene glycol bis (beta-aminoethyl ether) N,N'-tetraacetic acid) and varying amounts of calcium. When a KC1-based incubation medium was used, the oxidation of palmitate was inhibited when the concentration of free calcium was increased from about 0.1-10 microM. When a sucrose-based incubation medium was used, the basal rate of palmitate oxidation was about half of that observed with the KC1-medium and calcium had a stimulatory effect. With the KC1-medium the rate of oxygen consumption was inhibited by calcium with alpha-ketoglutarate as well as palmitate as the respiratory substrate. No inhibitory effect of calcium was observed with succinate or beta-hydroxybutyrate. With the KC1-medium and with alpha-ketoglutarate as the respiratory substrate, state 3 respiration but not state 4 respiration was inhibited by calcium. When the sucrose-medium was used, state 3 respiration was first inhibited by calcium, but this inhibition was gradually relieved and the respiratory rate finally became higher than it was before calcium addition. PMID:6724102

Borrebaek, B; Dolva, K; Singh, B

1984-01-01

373

Thiol-dependent passive K\\/Cl transport in sheep red cells: VII. Volume-independent freezing by iodoacetamide, and sulfhydryl group heterogeneity  

Microsoft Academic Search

Summary The sulfhydryl (SH) reagent iodoacetamide (IAAM) inhibits stimulation of Cl-dependent K transport in low K (LK) sheep red cells by another SH reagent, N-ethylmaleimide (NEM), without itself activating this transport pathway (J. Membrane Biol., 1983,73:257–261). We now report that IAAM alone, acting with a kinetic slower than NEM, sharply reduced the capability of the Cl-dependent K transport system to

P. K. Lauf

1987-01-01

374

Thiol-dependent passive K\\/Cl transport in sheep red cells: I. Dependence on chloride and external K + [Rb + ] ions  

Microsoft Academic Search

Summary Treatment with 2mm N-ethylmaleimide (NEM) caused a marked increase in K+ permeability of low K+ but not of high K+ sheep red cells suspended in isosmotic Cl- media with 10-4m ouabain. The Na+ permeability was unaltered. Kinetic analysis by K+ efflux and K+ or Rb+ influx measurements suggests that NEM primarily increased the bidirectional fluxes of K+ and Rb+,

P. K. Lauf

1983-01-01

375

Thiol-dependent passive K\\/Cl transport in sheep red cells: II. Loss of Cl ? and N-ethylmaleimide sensitivity in maturing high K + cells  

Microsoft Academic Search

Summary A fraction of the passive, ouabain-insensitive K+ fluxes in mature low K+ (LK) but not in high K+ (HK) sheep red cells requires the presence of Cl- anions and can be stimulated by volume expansion (Dunham, P.B., Ellory, J.C.,J. Physiol. (London)318:511–530, 1981) or treatment with 2mm N-ethylmaleimide (NEM) (Lauf, P.K., Theg., B.E.,Biochem. Biophys. Res. Commun.92:1422–1428, 1980). In the present

P. K. Lauf

1983-01-01

376

Thiol-dependent passive K\\/Cl transport in sheep red cells: III. Differential reactivity of membrane SH groups with N-ethylmaleimide and iodoacetamide  

Microsoft Academic Search

Summary Treatment with N-ethylmaleimide (NEM) is known to stimulate ouabain-insensitive, Cl--dependent K+ transport in low K+ (LK) but not in high K+ (HK) sheep red cells (Lauf, P.K., and Theg, B.E., 1980,Biophys. Biochem. Res. Commun.921422–1428). The dependence of this effect on the pH of pretreatment with NEM and\\/or iodoacetamide (IAA) was studied. Maximum stimulation of Cl--dependent K+ transport in LK

J. Bauer; P. K. Lauf

1983-01-01

377

Thiol-Dependent passive K\\/Cl transport in sheep red cells: IV. Furosemide inhibition as a function of external Rb + , Na + , and Cl ?  

Microsoft Academic Search

Summary The effect of the loop diuretic furosemide (4-chloro-N-furfuryl-5-sulfamoyl-anthranilic acid) on the thiol-dependent, ouabain-insensitive K(Rb)\\/Cl transport in low K+ sheep red cells was studied at various concentrations of extracellular Rb+, Na+ and Cl-. In Rb+-free NaCl media, 2×10-3m furosemide inhibited only one-half of thiol-dependent K+ efflux. In the presence of 23mm RbCl, however, the concentration of furosemide to produce 50%

P. K. Lauf

1984-01-01

378

Excretion of NaCl and KCl loads in mosquitoes. 2. Effects of the small molecule Kir channel modulator VU573 and its inactive analog VU342.  

PubMed

The effect of two small molecules VU342 and VU573 on renal functions in the yellow fever mosquito Aedes aegypti was investigated in vitro and in vivo. In isolated Malpighian tubules, VU342 (10 ?M) had no effect on the transepithelial secretion of Na(+), K(+), Cl(-), and water. In contrast, 10 ?M VU573 first stimulated and then inhibited the transepithelial secretion of fluid when the tubules were bathed in Na(+)-rich or K(+)-rich Ringer solution. The early stimulation was blocked by bumetanide, suggesting the transient stimulation of Na-K-2Cl cotransport, and the late inhibition of fluid secretion was consistent with the known block of AeKir1, an Aedes inward rectifier K(+) channel, by VU573. VU342 and VU573 at a hemolymph concentration of about 11 ?M had no effect on the diuresis triggered by hemolymph Na(+) or K(+) loads. VU342 at a hemolymph concentration of 420 ?M had no effect on the diuresis elicited by hemolymph Na(+) or K(+) loads. In contrast, the same concentration of VU573 significantly diminished the Na(+) diuresis by inhibiting the urinary excretion of Na(+), Cl(-), and water. In K(+)-loaded mosquitoes, 420 ?M VU573 significantly diminished the K(+) diuresis by inhibiting the urinary excretion of K(+), Na(+), Cl(-), and water. We conclude that 1) the effects of VU573 observed in isolated Malpighian tubules are overwhelmed in vivo by the diuresis triggered with the coinjection of Na(+) and K(+) loads, and 2) at a hemolymph concentration of 420 ?M VU573 affects Kir channels systemically, including those that might be involved in the release of diuretic hormones. PMID:25056106

Rouhier, Matthew F; Hine, Rebecca M; Park, Seokhwan Terry; Raphemot, Rene; Denton, Jerod; Piermarini, Peter M; Beyenbach, Klaus W

2014-10-01

379

Acid and alkali doped PBI electrolyte in electrochemical system  

NASA Astrophysics Data System (ADS)

In this work the conductivity of blank PBI membrane, acid doped PBI and alkaline doped PBI was systematically studied. A new methodology for sorption kinetics study in electrolyte solution has been established by monitoring the conductivity change during the sorption process. The model of the doping process and mechanism of conductivity are proposed. The performance of PBI (doped under optimum conditions) in fuel cell as PEM was evaluated. The experimental results show that the blank PBI in acid solution is an ionic insulator. It clarified the long time confusion in this area. The acid doped PBI membrane is an ionic conductor. The conductivity increases with the concentration of the acid solution. In high concentration acid solution, the conductivity increases with the type of acid in the order: H2SO 4 > H3PO4 > HClO4 > HNO3 > HCl. The kinetics of the doping process was studied, by a continuous method. The ionic conductivity mechanism was established. The PBI membranes doped with H2SO4 and H3PO4 exhibit better performance than NafionRTM. The doped FBI has more resistance to CO poison. 3% CO in H2 has little effect on the H3PO 4 doped PBI membrane at 185°C. The conductivity of the alkali doped PBI membrane changes with the concentration of the alkaline solution and the type of the alkalis. The conductivity has a maximum in KOH and NaOH solution. The maximum conductivity in KOH is higher than in NaOH and LiOH. It is about 5 times of that of NafionRTM in alkaline solution. The two-step sorption process in alkaline solution was observed. The first step is the permeation process of the alkalis in the PBI membrane. The permeation is the results of diffusion and interaction. It is concluded that the permeation process is controlled by the rate of interaction between the alkali and PBI molecule. The second step is the relaxation process in the membrane. This step contributes more to the conductivity for the membrane than the first step. The ionic conductivity mechanism was established. In solution the cations and OH- all participate in the transport of current. It is the OH- that breaks the bonds between PBI molecules and enables the cations pass through the membrane. The performance of alkali doped PBI (doped under optimum conditions) in fuel cell as PEM is as good as NafionRTM.

Xing, Baozhong

380

Hydrogeochemical contrasts between low and high arsenic groundwater and its implications for arsenic mobilization in shallow aquifers of the northern Yinchuan Basin, P.R. China  

NASA Astrophysics Data System (ADS)

Little is known about hydrogeochemical contrasts between low and high As groundwaters and their connection to As mobilization in the Yinchuan Basin. Investigations were carried out to evaluate As distribution and geochemical processes for As mobilization in three regions, including piedmont proluvial fans (PA), dry farmland (DF) and paddy farmland (PF). Ninety-two groundwater samples, 4 surface water samples, and 66 sediments samples were collected and analyzed for chemical and isotopic components. Results show that low As groundwater is generally found in PA. However, high As concentrations (up to 105 ?g L-1) are mainly observed in groundwaters from DF and PF, which are associated with reducing conditions. High As groundwater is characterized by high concentrations of NH4+, dissolved Mn, dissolved Fe and Fe(II), and low concentrations of NO3- and SO42-. The intensive irrigation in PF recharges the aquifers by vertical infiltration of the diverted Yellow River water, and leads to the higher redox potentials and the lower dissolved As in comparison with those in DF. Environmental isotopes (?18O and ?D) show that evaporation due to the intensive irrigation plays a minor role in As enrichment. The positive correlation between As and dissolved Fe suggests that groundwater As would result from the reductive dissolution of Fe oxides. Besides, dissolved P may be involved in competing with As for binding sites on Fe oxide minerals. Sediment As ranges between 3.94 and 75.2 mg kg-1. HCl-leached As accounts for 60% of total As in the sediments, while H3PO4-leached As accounts for 5%. Depth-matched samples show a good correlation between dissolved As and H3PO4-leached As in sediments. Arsenic distribution coefficient (Kd), calculated from H3PO4-leached As and dissolved As, ranges between 5.08 and 17.3 cm3 g-1, which generally depends on groundwater redox potentials. In reducing conditions, low values are found with As being preferentially partitioned into groundwater.

Guo, Qi; Guo, Huaming; Yang, Yuance; Han, Shuangbao; Zhang, Fucun

2014-10-01

381

Cytotoxicity and genotoxicity in vitro and irritation potency in vivo of two red phosphorus-based pyrotechnic smokes.  

PubMed

Two red phosphorus (RP)-based smokes (P60 and RPB), differing from each other mainly in RP content and in type of additive, were evaluated for in vitro cytotoxicity (cell viability by the trypan-blue exclusion method) and genotoxicity (comet assay) by exposing BEAS 2B human bronchial epithelial cells to the smokes in a laboratory-scale chamber for 5 min. The irritation potency of RPB smoke was studied in mice. A hexachloroethane-based smoke (HC/Zn/TNT) was used as a reference in the studies. A 5-min exposure of BEAS 2B cells to P60 smoke (1.1, 2.2 and 4.4 g/m(3), measured as H(3)PO(4)) did not induce any cytotoxic effects, while RPB smoke (1.3, 2.6 and 5.1g/m(3), measured as H(3)PO(4)) caused a mild decrease in cell viability at higher concentrations, without a clear dose-dependent effect. Neither of the RP smokes showed a genotoxic response in the comet assay with BEAS 2B cells, while HC/Zn/TNT was clearly genotoxic (0.9-3.5 g/m(3) as ZnCl(2)). In the mouse bioassay, head-only exposure to RPB smoke (20-450 mg/m(3) for 30 min as a single exposure, or 65-90 and 25-110 mg/m(3) - measured as H(3)PO(4) - for 30 min/day during 5 days) caused a concentration-dependent sensory irritation, which was evident as a decrease in respiratory rate and an increase in time-of-pause after inspiration, in a similar manner as with HC/Zn/TNT smoke. The concentration that caused a 50% decrease in respiratory frequency (RD(max)50) was calculated to be 1140 mg/m(3) for the RPB smoke and 145 mg/m(3) for the HC/Zn/TNT smoke. No pulmonary irritation was observed. PMID:20601099

Hemmilä, Matti; Hihkiö, Maija; Kasanen, Jukka-Pekka; Turunen, Mari; Järvelä, Merja; Suhonen, Satu; Pasanen, Anna-Liisa; Norppa, Hannu

2010-08-30

382

Journal of Crystal Growth 310 (2008) 29462953 Textural properties of synthetic nano-calcite produced by hydrothermal  

E-print Network

-calcite produced by hydrothermal carbonation of calcium hydroxide G. Montes-Hernandeza,Ã, A. Ferna´ ndez carbonation of calcium hydroxide (Ca(OH)2) at high pressure of CO2 (initial PCO2 ¼ 55 bar) and moderate conditions have a strong influence on the crystal size and surface area of the synthesized calcite crystals

Montes-Hernandez, German

2008-01-01

383

Journal of Crystal Growth ] (  

E-print Network

by hydrothermal carbonation of calcium hydroxide G. Montes-Hernandeza,Ã, A. Ferna´ ndez-Marti´neza,b , L. Charleta 2008 Communicated by S. Veesler Abstract The hydrothermal carbonation of calcium hydroxide (Ca(OH)2 and surface area of the synthesized calcite crystals. The present study is focused on the estimation

384

EINDHOVEN UNIVERSITY OF TECHNOLOGY Department of Mathematics and Computer Science  

E-print Network

carbonation reaction mechanism, namely CO2(g aq) + Ca(OH)2(s aq) CaCO3(aq s) + H2O. (1) In o and Applications Department of Mathematics and Computer Science Eindhoven University of Technology P.O. Box 513 Muntean December 19, 2011 Abstract We investigate the fast-reaction asymptotics for a one

Eindhoven, Technische Universiteit

385

Nutrient Availability from Douglas Fir Bark in Response to Substrate pH  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two studies were conducted to determine the influence of substrate pH on nutrient availability in douglas fir bark (DFB). Douglas fir bark was amended with either calcium carbonate (CaCO3) or calcium hydroxide [Ca(OH)2] at 13 rates to generate substrates with low to high pH. A non-amended control ...

386

A Simple Recipe for Whitening Old Newspaper Clippings.  

ERIC Educational Resources Information Center

Describes a method for experimenting with both whitening and deacidifying old newspaper clippings using sodium borohydride bleaching. Clippings are soaked in distilled water then immersed in sodium borohydride for 15-20 minutes. After rinsing with distilled water, the paper is washed with saturated Ca(OH)2 solution. Readers should not begin…

Carter, Henry A.

1995-01-01

387

DEVELOPMENT OF INFRARED METHODS FOR CHARACTERIZATION OF INORGANIC SULFUR SPECIES RELATED TO INJECTION DESULFURIZATION PROCESSES  

EPA Science Inventory

The report gives results of using photoacoutsic (PA) and diffuse reflectance (DR) detection methods in Fourier transform infrared spectroscopy (FTIRS) to evaluate the reactions of particulate CaO, CaCO3, and Ca(OH)2 samples with S02 at temperatures of 25-900 C. he work involved t...

388

A preliminary study of the carbon-isotopic content of ambient formic acid and two selected sources: Automobile exhaust and formicine ants  

Microsoft Academic Search

Relatively large quantities (˜1 mg) of formic acid have been collected from the atmosphere and subjected to carbon-isotopic analysis, as a means of source discrimination. Ambient formic acid was captured on Ca(OH)2-treated filters using a high-volume sampler. The collection method was not only efficient (>96%), but also appears to have low artifact production.

Bryan J. Johnson; George A. Dawson

1993-01-01

389

Process Engineering Thermodynamics 424304 E (4 sp)  

E-print Network

reaction is used to regenerate the CaO by Ca(OH)2 CaO + H2O. Thermodynamic data for the species involvedProcess Engineering Thermodynamics 424304 E (4 sp) Exam 20-3-2013 All support material is allowed output of the generator 25% is needed for the two pumps at the upper and lower levels (the energy input

Zevenhoven, Ron

390

Journal of Crystal Growth 308 (2007) 228236 Calcite precipitation from CO2H2OCa(OH)2 slurry under high  

E-print Network

efficiency (Ca(OH)2­CaCO3 conversion) was not significantly affected by pressure­temperature (PT) conditions after 24 h of reaction. In contrast, the initial rate of calcium carbonate precipitation increased from temperatures (30 and 90 1C). The morphology of precipitated particles was identified by transmission electron

Montes-Hernandez, German

2007-01-01

391

EFFECT OF RELATIVE HUMIDITY AND ADDITIVES ON THE REACTION OF SULFUR DIOXIDE WITH CALCIUM HYDROXIDE  

EPA Science Inventory

The paper gives results of a study of the reaction of SO2 with Ca(OH)2 at conditions similar to those of commercial-scale bag filters: 19-74 percent relative humidity (RH), 30.4-95 C, and 300-4000 ppm SO2. The study was carried out in a bench-scale reactor with powder reagent Ca(...

392

STRUCTURAL CHANGES IN SURFACTANT-MODIFIED SORBENTS DURING FURNACE INJECTION  

EPA Science Inventory

A calcium hydroxide [Ca(OH)2] sorbent modified by the addition of calcium lignosulfonate has recently been developed for use in the Environmental Protection Agency's limestone injection multistage burner process. The increased reactivity with sulfur dioxide (SO2) displayed by thi...

393

ACTIVATION AND REACTIVITY OF NOVEL CALCIUM-BASED SORBENTS FOR DRY SO2 CONTROL IN BOILERS  

EPA Science Inventory

Chemically modified calcium hydroxide (Ca(OH)2) sorbents developed in the U.S. Environmental Protection Agency's Air and Energy Engineering Research Laboratory (AEERL) for sulfur dioxide (SO2) control in utility boilers were tested in an electrically heated, bench-scale isotherma...

394

ENHANCEMENT OF REACTIVITY IN SURFACTANT-MODIFIED SORBENTS FOR SULFUR DIOXIDE CONTROL  

EPA Science Inventory

The paper discusses the enhancement of reactivity in surfactant-modified sorbents for S02 control. Injecting calcium-based sorbents into the post-flame zone of utility boilers can achieve S02 captures of 50-60% at a stoichiometry of 2. Calcium hydroxide-- Ca(OH)2--appears to be t...

395

LIGNOSULFONATE-MODIFIED CALCIUM HYDROXIDE FOR SULFUR DIOXIDE CONTROL  

EPA Science Inventory

The article discusses the use of lignosulfonate-modified calcium hydroxide Ca(OH)2 for sulfur dioxide (SO2) control. The limestone injection multistage burner (LIMB) process is currently being developed at the U.S. EPA as a low cost retrofittable technology for controlling oxides...

396

ENHANCEMENT OF REACTIVITY IN SURFACTANT-MODIFIED SORBENTS FOR SULFUR DIOXIDE CONTROL  

EPA Science Inventory

Injection of calcium-based sorbents into the postflame zone of utility boilers is capable of achieving sulfur dioxide (SO2) captures of 50-60% at a stoichiometry of 2. Calcium hydroxide [Ca(OH)2] appears to be the most effective commercially available sorbent. Recent attempts to ...

397

SOX OUT ON A LIMB (LIMESTONE INJECTION MULTISTAGE BURNER)  

EPA Science Inventory

The paper describes the most recent results from the Limestone Injection Multistage Burner (LIMB) program, covering results from the wall-fired demonstration. Tests were conducted to determine the efficacy of commercial calcium hydroxide (Ca(OH)2) and of calcium-lignosulfonate-mo...

398

Interactive Effects of Soil ph, Halosulfuron Rate, and Application Method on Carryover to Turnip Green and Cabbage.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field studies were conducted in 2006 and 2007 to evaluate the tolerance of autumn-planted cabbage and turnip green to halosulfuron applied the previous spring to cantaloupe. Main plots were three levels of soil pH; maintained at a natural pH level, pH raised with Ca(OH)2, and pH lowered with Al2(SO...

399

THE CHARACTERIZATION OF A SOLID SORBENT WITH CRYSTALLITE SIZE AND STRAIN DATA FROM X-RAY DIFFRACTION LINE BROADENING  

EPA Science Inventory

The paper gives results of the characterization of a solid sorbent with crystallite size and strain data from x-ray diffraction line broadening, as part of an EPA investigation of the injection of dry Ca(OH)2 into coal-fired electric power plant burners for the control of SO2 emi...

400

Synthesis of a Se0 /Calcite Composite Using Hydrothermal  

E-print Network

Synthesis of a Se0 /Calcite Composite Using Hydrothermal Carbonation of Ca(OH)2 Coupled in a batch system by hydrothermal carbonation of calcium hydroxide under high CO2-Ar pressure (90 bar of Geological Processes, UniVersity of Oslo, Norway, LCABIE, IPREM, UMR CNRS 5254, UniVersite´ de Pau et des

Montes-Hernandez, German

401

CALCINATION OF CALCIUM HYDROXIDE SORBENT IN THE PRESENCE OF SO2 AND ITS EFFECT ON REACTIVITY  

EPA Science Inventory

The paper discusses the calcination of Ca(OH)2 sorbent in the presence of SO2 and its effect on reactivity. When Ca(0H)2 is calcined in an isothermal flow reactor with 300 ppm or less SO2, the structure of the sorbent is characterized by retention of higher pore volumes and surfa...

402

REACTION MECHANISMS OF DRY CA-BASED SORBENTS WITH GASEOUS HCL  

EPA Science Inventory

The paper discusses an investigation of the mechanisms of HCl reaction with dry Ca(OH)2 or CaO sorbents in flue gas cleaning applications using differential scanning calorimetry (DSC), thermogravimetry (TGA), and X-ray diffraction (XRD). hort-time differential reactor (STDR) was ...

403

FURNACE SORBENT REACTIVITY TESTING FOR CONTROL OF SO2 EMISSIONS FROM ILLINOIS COALS  

EPA Science Inventory

Research was undertaken to evaluate the potential of furnai sorbent injection (FSI) for sulf dioxide (S02) emission controlcoal-fired boilers utilizing coals indigenous to Illinois. Tests were run using four coals from the Illinois Basin and six calcium hydroxide [Ca(OH)2], sorbe...

404

FURNACE SURBENT REACTIVITY TESTING FOR CONTROL OF SO2 EMISSIONS FROM ILLINOIS COALS  

EPA Science Inventory

Research was undertaken to evaluate the potential of furnai sorbent injection (FSI) for sulf dioxide (S02) emission controlcoal-fired boilers utilizing coals indigenous to Illinois. Tests were run using four coals from the Illinois Basin and six calcium hydroxide [Ca(OH)2], sorbe...

405

Dentinal tubule disinfection with 2% chlorhexidine, garlic extract, and calcium hydroxide against Enterococcus faecalis by using real-time polymerase chain reaction: In vitro study  

PubMed Central

Aim: To compare the efficacy of garlic extract with 2% chlorhexidine (CHX) and calcium hydroxide Ca(OH)2 in disinfection of dentinal tubules contaminated with Enterococcus faecalis by using real-time polymerase chain reaction (PCR). Materials and Methods: Agar diffusion test was done to evaluate the minimum inhibitory concentration of garlic extract against E. faecalis. Forty human extracted mandibular premolar teeth were selected for this study, access cavity was prepared and cleaning and shaping was done. Middle third of the root was cut using a rotary diamond disc. The teeth specimens were inoculated with E. faecalis for 21 days. Specimens were divided into four groups---Group 1: 2% CHX, Group 2: Garlic extract, Group 3: Ca(OH)2, and Group 4: Saline (negative control). The intracanal medicaments were packed inside the tooth specimens and incubated for 5 days. The dentinal chips were collected at 400 ?m depth using a Gates-Glidden drill, following which DNA isolation was done. The specimens were analyzed using real-time PCR. The results were then statistically analyzed using one-way analysis of variance, followed by post hoc Tukey's honestly significant difference (HSD) multiple comparison of means. Results: Threshold cycle (Ct) values of 2% CHX was found to be 32.4, garlic extract to be 27.5, and Ca(OH)2 to be 25.6. Conclusion: A total of 2% CHX showed the maximum efficacy against E. faecalis, followed by garlic extract and Ca(OH)2. PMID:23833449

Eswar, Kandaswamy; Venkateshbabu, Nagendrababu; Rajeswari, Kalaiselvam; Kandaswamy, Deivanayagam

2013-01-01

406

REACTION MECHANISMS OF DRY CA-BASED SORBENTS WITH GASEOUS HCL  

EPA Science Inventory

The mechanisms of HC1 reaction with dry Ca(OH)2 or CaO sorbents in flue gas cleaning applications were investigated by differential scanning calorimetry (DSC), thermogravimetry, and X-ray diffraction. A short-time differential reactor (STDR) was used to contact 1000 ...

407

Pozzolanic Activity of Volcanic Tuff and Suevite: Effects of Calcination  

Microsoft Academic Search

The pozzolanic activity of two volcanic tuffs (Rhenish Trass) and the impact breccia Suevite (Bavarian Trass) were studied experimentally. Analcite, phillipsite and smectite present in the pozzolanas were investigated seperately. All samples were calcined at 500 and 800°C, respectively. Both the untreated and calcined materials were mixed with a Ca(OH)2 solution, CH, and with a lime mortar. The amounts of

E. Liebig; E. Althaus

1998-01-01

408

FUNDAMENTAL STUDIES OF DRY INJECTION OF CALCIUM-BASED SORBENTS FOR S02 CONTROL IN UTILITY BOILERS  

EPA Science Inventory

The report describes research to determine the mechanisms which limit the extent of reaction between SO2 and calcium-based sorbents (CaCO3 and Ca(OH)2) by measuring the in situ physical structure and reactivity of sorbent injected into a combustion environment for residence times...

409

Activation and reactivity of novel calcium-based sorbents for dry SO2 control in boilers (journal article)  

SciTech Connect

Chemically modified Ca(OH)2 sorbents for SO2 control in utility boilers were tested in an electrically heated, bench-scale isothermal flow reactor, operated at between 700 and 1000 C and residence times of from 0.6 to 2 sec calculated from bulk gas flowrates. Novel surfactant-modified Ca(OH)2 (SM-Ca(OH)2) sorbents were compared to conventional Ca(OH)2 produced by dry hydration (DH-Ca(OH)2). Sorbents were activated in the flow reactor. The gas composition was 5 vol % oxygen with the balance nitrogen. Activated sorbents, SM-CaO and DH-CaO, were size classified with an inertial cascade impactor downstream of the flow reactor. The structure of each separated fraction (six trays plus preimpactor, D50 from 0.74 to > 11.9 micrometers) was characterized by nitrogen adsorption. For each size fraction measured, the surface area was higher for SM-CaO than for DH-CaO. The effect of thermal sintering was the increase of median pore size as a result of eliminating fine pores (below 100 A). Changes in the pore structure of Ca(OH)2 sorbents reacting with SO2 were also investigated. The effect of thermal sintering on pore structure of sorbents reacting with SO2 was eliminated. The degree of conversion was controlled by varying gas-phase mass transfer resistance (SO2 concentrations from 50 to 3000 ppm).

Jozewicz, W.; Kirchgessner, D.A.

1989-01-01

410

Zentrum f ur Technomathematik Fachbereich 3 --Mathematik und Informatik  

E-print Network

places. But using such fine grid everywhere, the computation will get very slow, especially two and three everywhere, because slowly varying concentration fields can easily approximated a relatively coarse mesh carbonation concrete, involving the concentrations 1 c CO 2 and liquid phases, c Ca(OH) 2 water, and total

Bremen, Universität

411

INVESTIGATION OF PRODUCT-LAYER DIFFUSIVITY FOR CAO SULFATION  

EPA Science Inventory

The paper gives results of comparisons of the sulfation rates of CaO prepared from Ca(OH)2 and CaCO3, using six types of each precursor derived from the same natural limestones. The particles were small enough to eliminate all transport resistances except diffusion through the Ca...

412

SUMMARY REPORT: SULFUR OXIDES CONTROL TECHNOLOGY SERIES: FLUE GAS DESULFURIZATION - SPRAY DRYER PROCESS  

EPA Science Inventory

Described spray dryer flue gas desulfurization (FGD), which is a throwaway process in which sulfur dioxide (SO2) is removed from flue gas by an atomized lime slurry [Ca(OH)2]. he hot flue gas dries the droplets to form a dry waste product, while the absorbent reacts with sulfur d...

413

CALCINATION AND SINTERING MODELS FOR APPLICATION TO HIGH-TEMPERATURE, SHORT-TIME SULFATION OF CALCIUM-BASED SORBENTS  

EPA Science Inventory

To simulate the staged availability of transient high surface area CaO observed in high-temperature flow-reactor data, the rate of calcination of CaCO3 or Ca(OH)2 is described by an empirical modification of the shrinking-core model. The physical model depicts particle decomposi...

414

CALCIUM OXIDE SINTERING IN ATMOSPHERES CONTAINING WATER AND CARBON DIOXIDE  

EPA Science Inventory

The paper gives results of measurements of the effects of water vapor and CO2 on the sintering rate of nascent CaO, as a function of partial pressure and temperature using CaO prepared by rapid decomposition of CaCO3 and CA(OH)2. Each gas strongly catalyzed the sintering process ...

415

Evaluation of Mineral Trioxide Aggregate and Calcium Hydroxide Cement as Pulp-capping Agents in Human Teeth  

Microsoft Academic Search

This study evaluated the histomorphologic response of human dental pulps capped with mineral trioxide aggregate (MTA) and Ca(OH)2 cement (CH). Pulp exposures were performed on the occlusal floor of 40 human permanent premolars. After that, the pulp was capped either with CH or MTA and restored with composite resin. After 30 and 60 days, teeth were extracted and processed for

Maria de Lourdes R. Accorinte; Roberto Holland; Alessandra Reis; Marcelo C. Bortoluzzi; Sueli S. Murata; Eloy Dezan; Valdir Souza; Loguercio Dourado Alessandro

2008-01-01

416

Valorization of phosphogypsum as hydraulic binder.  

PubMed

Phosphogypsum (calcium sulfate) is a naturally occurring part of the process of creating phosphoric acid (H(3)PO(4)), an essential component of many modern fertilizers. For every tonne of phosphoric acid made, from the reaction of phosphate rock with acid, commonly sulfuric acid, about 3t of phosphogypsum are created. There are three options for managing phosphogypsum: (i) disposal or dumping, (ii) stacking, (iii) use-in, for example, agriculture, construction, or landfill. This paper presents the valorization of two Tunisian phosphogypsums (referred as G and S) in calcium sulfoaluminate cement in the following proportions: 70% phosphogypsum-30% calcium sulfoaluminate clinker. The use of sample G leads to the production of a hydraulic binder which means that it is not destroyed when immersed in water. The binder including sample S performs very well when cured in air but is not resistant in water. Formation of massive ettringite in a rigid body leads to cracking and strength loss. PMID:18433998

Kuryatnyk, T; Angulski da Luz, C; Ambroise, J; Pera, J

2008-12-30

417

Theoretical calculation of p Kas of phosphoric (V) acid in the polarisable continuum and cluster-continuum models  

NASA Astrophysics Data System (ADS)

The accuracy of the polarisable continuum model (PCM) and the mixed cluster-continuum model in the prediction of the absolute values of the three consecutive p Kas of phosphoric (V) acid has been checked. PCM calculations at the MP2/6-31+G(d,p) level reproduce the first p Ka with an acceptable error. However, they fail significantly for the next two p Kas and increasing the level of theory to G3B3 compound method does not provide any improvement. On the other hand, cluster-continuum calculations at the same MP2 level adequately predict all three dissociation constants of H 3PO 4. The number of necessary solvating water molecules depends on the polarising power of the anion and increases with the charge of the phosphate group. The obtained results indicate the validity of the cluster-continuum approach for the prediction of reliable p Ka values of polyprotic inorganic acids.

?miechowski, Maciej

2009-04-01

418

Mechanism of the protonation of azulenes in aqueous solutions of acids  

NASA Astrophysics Data System (ADS)

In aqueous solutions of strong acids (H2SO4, H3PO4, and HCl) containing azulene, the fast reversible protonation of azulene is accompanied by the slow formation of a disperse dark violet dye insoluble in acids, alcohol, and heptane. On the basis of the kinetic specifics of this reaction and the nonlinear (nearly reciprocal quadratic) dependence of the concentrations ratio of their cationic and neutral forms on the Hammett acidity function known for azulene and 14 of its derivatives, azulene is shown not to be a Hammett base. A mechanism for the reversible reactions of the azulenium cation is proposed that considers supramolecular dimers to be the basic state of azulene and its derivatives. The scheme includes reactions of the unstable intermediate ? complexes formed from the dimers and hydrated hydrogen cations; the complexes quickly dissociate in the opposite direction and react with the hydrated protons to yield azulenium cations and unstable molecules that induce polymerization of the dimers.

Mikheev, Yu. A.; Guseva, L. N.; Ershov, Yu. A.

2013-10-01

419

Redetermination of AgPO3  

PubMed Central

Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ?). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure. PMID:21522230

Terebilenko, Katherina V.; Zatovsky, Igor V.; Ogorodnyk, Ivan V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

2011-01-01

420

Redetermination of AgPO(3).  

PubMed

Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ?). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure. PMID:21522230

Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

2011-01-01

421

Effects of acid and alkali promoters on compressed liquid hot water pretreatment of rice straw.  

PubMed

In this study, effects of homogeneous acid and alkali promoters on efficiency and selectivity of LHW pretreatment of rice straw were studied. The presences of acid (0.25%v/v H2SO4, HCl, H3PO4, and oxalic acid) and alkali (0.25 w/v NaOH) efficiently promoted hydrolysis of hemicellulose, improved enzymatic digestibility of the solids, and lower the required LHW temperature. Oxalic acid was a superior promoter under the optimal LHW conditions at 160 °C, leading to the highest glucose yield from enzymatic hydrolysis (84.2%) and the lowest formation of furans. Combined with hydrolyzed glucose in the liquid, this resulted in the maximal 91.6% glucose recovery from the native rice straw. This was related to changes in surface area and crystallinity of pretreated biomass. The results showed efficiency of external promoters on increasing sugar recovery and saving energy in LHW pretreatment. PMID:25181697

Imman, Saksit; Arnthong, Jantima; Burapatana, Vorakan; Champreda, Verawat; Laosiripojana, Navadol

2014-11-01

422

Fabrication of Monolithic Sapphire Membranes for High Tc Bolometer Array Development  

NASA Technical Reports Server (NTRS)

This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in r-plane sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to hot H2SO4:H3PO4 etchant, will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask system to: (1) changes in the surface morphology and elemental concentration of the Pt/Cr thin film layers and (2) etch pit formation on the sapphire surface will be presented.

Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L.

2003-01-01

423

Fabrication of Monolithic Sapphire Membranes for High T(sub c) Bolometer Array Development  

NASA Technical Reports Server (NTRS)

This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in r-plane single crystal sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to boiling H2SO4:H3PO4 etchant will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask system to: (1) changes in the surface morphology (2) elemental concentration of the Pt/Cr thin film layers and (3) etch pit formation on the sapphire surface will be presented.

Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L.

2004-01-01

424

Properties of nanostructures obtained by anodization of aluminum in phosphoric acid at moderate potentials  

NASA Astrophysics Data System (ADS)

The influence of the process duration, anodizing potential and methanol addition on the structural features of porous anodic alumina formed in a 0.3 M H3PO4 solutions by twostep self-organized anodizing was investigated for potentials ranging from 100 to 170 V. The structural features of porous structures including pore diameter and interpore distance were evaluated from FE-SEM top-view images for samples anodized in the presence and absence of methanol. For the highest studied anodizing time and methanol volume fraction, an excellent agreement between experimental values of the interpore distance and theoretical predictions was observed. The pore arrangement regularity was analyzed for various electrolyte compositions and anodizing potentials. It was found that the regularity ratio of porous alumina increases linearly with increasing anodizing potential and time. The addition of methanol improves the quality of nanostructures and especially better uniformity of pore sizes is observed in the presence of the highest studied methanol content.

Zaraska, L.; Sulka, G. D.; Jasku?a, M.

2009-01-01

425

CO2 Adsorption on Activated Carbon Honeycomb-Monoliths: A Comparison of Langmuir and Tóth Models  

PubMed Central

Activated carbon honeycomb-monoliths with different textural properties were prepared by chemical activation of African palm shells with H3PO4, ZnCl2 and CaCl2 aqueous solutions of various concentrations. The adsorbents obtained were characterized by N2 adsorption at 77 K, and their carbon dioxide adsorption capacities were measured at 273 K and 1 Bar in volumetric adsorption equipment. The experimental adsorption isotherms were fitted to Langmuir and Tóth models, and a better fit was observed to Tóth equation with a correlation coefficient of 0.999. The maximum experimental values for adsorption capacity at the highest pressure (2.627–5.756 mmol·g?1) are between the calculated data in the two models. PMID:22942710

Vargas, Diana P.; Giraldo, Liliana; Moreno-Piraján, Juan C.

2012-01-01

426

Molecular emission and temperature measurements from single-bubble sonoluminescence.  

PubMed

Single-bubble sonoluminescence (SBSL) spectra in H2O show featureless continuum emission. From an acoustically driven, moving bubble in phosphoric acid (H3PO4), we observe very strong molecular emission from excited OH radicals (?310??nm), which can be used as a spectroscopic thermometer by fitting the experimental SBSL spectra to the OH A?2?+ - X?2? rovibronic transitions. The observed emission temperature (T(em)) ranges from 6200 to 9500 K as the acoustic pressure (P(a)) varies from 1.9 to 3.1 bar and from 6000 to >10,000??K as the dissolved monatomic gas varies over the series from He to Xe. PMID:20867304

Xu, Hangxun; Suslick, Kenneth S

2010-06-18

427

Simple and sensitive high-performance liquid chromatographic method for the determination of 1,5-benzodiazepine clobazam and its active metabolite N-desmethylclobazam in human serum and urine with application to 1,4-benzodiazepines analysis.  

PubMed

A HPLC-UV determination of clobazam and N-desmethylclobazam in human serum and urine is presented. After simple liquid-liquid extraction with dichloromethane the compounds and an internal standard diazepam were separated on a Supelcosil LC-8-DB column at ambient temperature under isocratic conditions using the mobile phase: CH3CN-water-0.5 M KH2PO4-H3PO4 (440:540:20:0.4, v/v and 360:580:60:0.4, v/v for serum and urine, respectively). The detection was performed at 228 nm with limits of quantification of 2 ng/ml for serum and 1 ng/ml for urine. Relative standard deviations for intra- and inter-assay precision were found below 8% for both compounds for all the tested concentrations. The described procedure may be easily adapted for several 1,4-benzodiazepines. PMID:11204222

Kunicki, P K

2001-01-01

428

Novel Application of ZSM-5 Zeolite: Corrosion-Resistant Coating in Chemical Process Industry  

NASA Astrophysics Data System (ADS)

As-synthesized zeolite ZSM-5 containing the structure-directing agent, tetrapropyl ammonium bromide, when used as a coating material on mild steel substrate material, has been found to offer a promising corrosion resisting results against HCl, HNO3, H3PO4, and H2SO4 of various concentrations at temperatures up to 60 °C under stagnant and stirred conditions. Stable and continuous coated layer is observed under the conditions studied in this work by weight loss and electrochemical methods. Encouraging results in terms of corrosion inhibition efficiency indicate high potential with zeolite (Si/Al ratio 25) material. Material costs compare favorably for zeolite coating against the conventionally used materials. Summarily, zeolite offers an environment-friendly and cost-effective alternate to the other toxic and carcinogenic materials as corrosion-resistant coating.

Pande, H. B.; Parikh, P. A.

2013-01-01

429

Shallow Etching of GaAs/AlGaAs Heterostructures in Context of HEMT Fabrication  

NASA Astrophysics Data System (ADS)

Gate recess etching is a key step in the fabrication process of high electron mobility transistors (HEMTs). The thin n+ cap layer needs to be etched without destroying the underlying supply layer. Conventional GaAs etch solutions based on H2SO4 or H3PO4 acids have high etch rates and hence present difficulties in the control of etch rates for shallow etches. Etches using Citric acid (CA) based solutions have been reported to have potential in such applications. Such etches with varying ratio of CA:H2O2:H2O are compared. A suitable recipe has been obtained for shallow gate recess etch and a HEMT is fabricated using the process.

Kumar, Ch. Ravi; Rajaram, G.

2011-07-01

430

Adsorption of phenols from wastewater.  

PubMed

The present work involves an investigation of the possible use of coal, residual coal, and residual coal treated with H3PO4 as a means of removal of phenol from wastewater. The study was realized using batch experiments, with synthetic wastewater having phenol concentration of 1000 ppm. Other low-cost adsorbents such as petroleum coke, coke breeze, rice husk, and rice husk char have also been used. The effect of system variables such as pH, contact time, and temperature has been investigated. The suitability of the Freundlich, Langmuir, and Redlich-Peterson adsorption models to the equilibrium data was investigated for each phenol-adsorbent system. The results showed that the equilibrium data for all the phenol-sorbent systems fitted the Redlich-Peterson model best. Kinetic modeling of removal of phenols was done using the Lagergren first-order rate expression. A series of column experiments were performed to determine the breakthrough curves. PMID:15914144

Ahmaruzzaman, M; Sharma, D K

2005-07-01

431

Chemical aminoacylation of transfer ribonucleic acid. The reaction of Escherichia coli tRNA with ethyl N-benzyloxycarbonylorthoglycinate.  

PubMed

The alpha-carbethoxypentadecyltrimethylammonium (Septonex) salt of tRNA (Ib) was condensed with ethyl N-benzyloxycarbonylorthoglycinate (II) in dimethylformamide in vacuo and in the presence of H3PO4 as catalyst. Pancreatic RNAase degradation and phenylalanine acceptor activity showed a 55--60% conversion to the 2',3'-cyclic orthoglycinate derivative of tRNA (IIIb). The orthoester grouping of IIIb was quantitatively hydrolyzed in 80% formic acid at 0 degrees C for 15 min to give 2'(3')-O-(N-benzyloxycarbonyl)glycyl tRNA (IVb). The latter was stripped at pH 8.8 to give tRNA whose behavior on DEAE cellulose column and gel electrophoresis was similar to that of starting tRNA. The phenylalanine acceptor activity amounted to almost 80% of the starting tRNA. PMID:336095

Hwang, J S; Bhuta, P; Zemlicka, J

1977-11-16

432

Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy.  

PubMed

Synchrotron-based X-ray tomographic microscopy is investigated for imaging the local distribution and concentration of phosphoric acid in high-temperature polymer electrolyte fuel cells. Phosphoric acid fills the pores of the macro- and microporous fuel cell components. Its concentration in the fuel cell varies over a wide range (40-100?wt% H3PO4). This renders the quantification and concentration determination challenging. The problem is solved by using propagation-based phase contrast imaging and a referencing method. Fuel cell components with known acid concentrations were used to correlate greyscale values and acid concentrations. Thus calibration curves were established for the gas diffusion layer, catalyst layer and membrane in a non-operating fuel cell. The non-destructive imaging methodology was verified by comparing image-based values for acid content and concentration in the gas diffusion layer with those from chemical analysis. PMID:25343801

Eberhardt, S H; Marone, F; Stampanoni, M; Büchi, F N; Schmidt, T J

2014-11-01

433

Preparation and properties of titanium oxide film on NiTi alloy by micro-arc oxidation  

NASA Astrophysics Data System (ADS)

Titanium oxide ceramic coatings were prepared by micro-arc oxidation (MAO) in galvanostatic regime on biomedical NiTi alloy in H3PO4 electrolyte using DC power supply. The surface of the coating exhibited a typical MAO porous and rough structure. The XPS analysis indicated that the coatings were mainly consisted of O, Ti, P, and a little amount of Ni, and the concentration of Ni was greatly reduced compared to that of the NiTi substrate. The TF-XRD analysis revealed that MAO coating was composed of amorphous titanium oxide. The coatings were tightly adhesive to the substrates with the bonding strength more than 45 MPa, which was suitable for medical applications. The curves of potentiodynamic porlarization indicated that the corrosion resistance of NiTi alloy was significantly improved due to titanium oxide formation on NiTi alloy by MAO.

Wang, H. R.; Liu, F.; Zhang, Y. P.; Yu, D. Z.; Wang, F. P.

2011-04-01

434

Anodized titania: Processing and characterization to improve cell-materials interactions for load bearing implants  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate in vitro cell-materials interactions using human osteoblast cells on anodized titanium. Titanium is a bioinert material and, therefore, gets encapsulated after implantation into the living body by a fibrous tissue that isolates them from the surrounding tissues. In this work, bioactive nonporous and nanoporous TiO2 layers were grown on commercially pure titanium substrate by anodization process using different electrolyte solutions namely (1) H3PO 4, (2) HF and (3) H2SO4, (4) aqueous solution of citric acid, sodium fluoride and sulfuric acid. The first three electrolytes produced bioactive TiO2 films with a nonporous structure showing three distinctive surface morphologies. Nanoporous morphology was obtained on Ti-surfaces from the fourth electrolyte at 20V for 4h. Cross-sectional view of the nanoporous surface reveals titania nanotubes of length 600 nm. It was found that increasing anodization time initially increased the height of the nanotubes while maintaining the tubular array structure, but beyond 4h, growth of nanotubes decreased with a collapsed array structure. Human osteoblast (HOB) cell attachment and growth behavior were studied using an osteoprecursor cell line (OPC 1) for 3, 7 and 11 days. Colonization of the cells was noticed with distinctive cell-to-cell attachment on HF anodized surfaces. TiO2 layer grown in H2SO4 electrolyte did not show significant cell growth on the surface, and some cell death was also noticed. Good cellular adherence with extracellular matrix extensions in between the cells was noticed for samples anodized with H3PO 4 electrolyte and nanotube surface. Cell proliferation was excellent on anodized nanotube surfaces. An abundant amount of extracellular matrix (ECM) between the neighboring cells was also noticed on nanotube surfaces with filopodia extensions coming out from cells to grasp the nanoporous surface for anchorage. To better understand and compare cell-materials interactions, anodized nanoporous sample surfaces were etched with different patterns. Preferential cell attachment was noticed on nanotube surfaces compared to no cells on etched patterned surface. Cell adhesions and differentiation were more pronounced with vinculin protein and alkaline phosphatase, respectively, on anodized surfaces. MTT assays showed increase in living cell density and higher proliferation on H3PO4, HF and nanotube surfaces. When anodized surfaces were compared for cell materials interaction, it was noticed that each of the surfaces has different surface properties that led to variations in cell-materials interactions. It was clear that rough surface morphology, high surface energy, and low value of the contact angles were important factors for better cell materials interaction. Mineralization study was done in simulated body fluid (SBF) with ion concentration nearly equal to human blood plasma to further understand biomimetic apatite deposition behavior. Similar to cell-materials interaction, variation in mineral deposition behavior was also noticed for films grown with different electrolytes. These results clearly show that nonporous titania in H3PO4, HF electrolytes and nanotubes can significantly increase biocompatibility of Ti implants, which has the potential to reduce the healing time and increase in vivo lifetime for these implants.

Das, Kakoli

435

[Determination of antidangdruff agent salicylic acid, zinc pyrithione, octopirox, climbazole and ketoconazole in shampoo by high performance liquid chromatography].  

PubMed

A high performance liquid chromatography method was established for determination of antidangdruff agent salicylic acid,zinc pyrithione, octopirox, climbazole and ketoconazole in shampoo on a C18 column using acetonitrile-metholaqueous solution (10 mmol/L KH2 PO4 and 5 mmol/L EDTANa2, pH is adjusted to 4.0 with H3 PO4) (50:10:40) as mobile phase at a flow rate of 1.0 ml/min, with the column temperature 25 degrees C and detection wave 230nm. The precision was less than 3.8% and recovery varied from 92.7% to 104.9%. The experimental results showed that the method was simple, precise and accurate. PMID:16329615

Yang, Yan-Wei; Zhu, Ying; Su, Xiao-Qing

2005-09-01

436

Electrochemical behavior and voltammetric determination of vanillin based on an acetylene black paste electrode modified with graphene-polyvinylpyrrolidone composite film.  

PubMed

The graphene-polyvinylpyrrolidone composite film modified acetylene black paste electrode (GR-PVP/ABPE) was fabricated and used to determine vanillin. In 0.1M H3PO4 solution, the oxidation peak current of vanillin increased significantly at GR-PVP/ABPE compared with bare ABPE, PVP/ABPE and GR/ABPE. The oxidation mechanism was discussed. The experimental conditions that exert influence on the voltammetric determination of vanillin, such as supporting electrolytes, pH values, accumulation potential and accumulation time, were optimized. Besides, the interference, repeatability, reproducibility and stability measurements were also evaluated. Under the optimal experimental conditions, the oxidation peak current was proportional to vanillin concentration in the range of 0.02-2.0?M, 2.0-40?M and 40-100?M. The detection limit was 10nM. This sensor was used successfully for vanillin determination in various food samples. PMID:25766813

Deng, Peihong; Xu, Zhifeng; Zeng, Rongying; Ding, Chunxia

2015-08-01

437

Investigation by infrared absorption spectroscopy into the chemical mechanisms of the wet process synthesis of some calcium phosphates  

NASA Astrophysics Data System (ADS)

The present work describes the reactions of wet process synthesis, of some calcium phosphates, such as tricalcium phosphate (Ca{3}(PO{4})2) and hydroxyapatite (Ca{10}(PO{4})6(OH){2}). These reactions of synthesis are acido-basic reactions between the phosphoric acid (H{3}PO{4}) and calcium carbonates (CaCO{3}).The evolution of these reactions (and the concerned chemical mechanisms) were followed by mid infrared spectroscopy absorption. Indeed, in the first stage of these three reactions in which the medium is strongly acidic, favours the formation of a stable intermediate compound, which is the brushite.During the reaction, the concentration of phosphoric acid decreases, the pH increases and the brushite becomes unstable, thus it evolves to a more stable calcium phosphate under these new pH conditions. This later product was either the tricalcium phosphate or hydroxyapatite, according to the pH solution.

Essaddek, A.; Elgadi, M.; Mejdoubi, E.; Elansari, L. L.; Moradi, K.; Karroua, M.

2005-03-01

438

Fabrication of highly ordered nanoporous alumina films by stable high-field anodization  

NASA Astrophysics Data System (ADS)

Stable high-field anodization (1500-4000 A m-2) for the fabrication of highly ordered porous anodic alumina films has been realized in a H3PO4-H2O-C2H5OH system. By maintaining the self-ordering voltage and adjusting the anodizing current density, high-quality self-ordered alumina films with a controllable inter-pore distance over a large range are achieved. The high anodizing current densities lead to high-speed film growth (4-10 µm min-1). The inter-pore distance is not solely dependent on the anodizing voltage, but is also influenced by the anodizing current density. This approach is simple and cost-effective, and is of great value for applications in diverse areas of nanotechnology.

Li, Yanbo; Zheng, Maojun; Ma, Li; Shen, Wenzhong

2006-10-01

439

On the surface diffusion of Pt adatoms in acidic solutions  

NASA Astrophysics Data System (ADS)

Surface diffusion coefficients, Ds, of platinum adatoms were determined by means of in situ electrochemical methods on columnar-structured Pt electrodes immersed in 1M HClO 4, 1M H 3PO 4 and 0.5M H 2SO 4 electrolytic solutions. Measurements were made at different potential values covering the range from hydrogen coverage formation to that in which platinum oxides begin to be formed. The Ds values observed confirm an adsorbate induced relaxation of the Pt surface atoms and could explain why restructuring of Pt electrodes has been observed under some experimental conditions. A study of the variation of D s with temperature leads to values of ?H?f and ?S? at three potentials, which can be explained according to interactions between adsorbates and Pt surface sites. According to the data obtained, a surface diffusion mechanism in three steps is formulated, in which different steps become rate determining at different potential ranges.

Jubrías, J. J. Martínez; Hidalgo, M.; Marcos, M. L.; Velasco, J. González

1996-10-01

440

N-polar GaN etching and approaches to quasi-perfect micro-scale pyramid vertical light-emitting diodes array  

NASA Astrophysics Data System (ADS)

N-polar GaN etching process and mechanism has been investigated in detail by varying the etching parameter (etchant temperature, etchant concentration, and etching duration) in KOH and H3PO4. Quasi-perfect micro-scale hexagonal pyramids vertical light emitting diodes (?-HP VLEDs) array with least active area loss (<12%) has been fabricated by N-polar etching. The ?-HP VLEDs shows massively improved crystal quality with X-ray diffraction full width at half maxima decreased from 442 s to 273 s, and the room temperature minority carriers decay time increased from 252 ps to 747 ps. Temperature dependence of photoluminescence result reveals a ˜30% improved internal quantum efficiency, and transmission electron microscope further reveals its quasi-perfect crystalline quality clearly.

Wang, Liancheng; Ma, Jun; Liu, Zhiqiang; Yi, Xiaoyan; Yuan, Guodong; Wang, Guohong

2013-10-01

441

Synthesis and structural characterisation using Rietveld and pair distribution function analysis of layered mixed titanium-zirconium phosphates  

NASA Astrophysics Data System (ADS)

Crystalline metal (IV) phosphates with variable zirconium-to-titanium molar ratios of general formula (Ti 1- xZr x)(HPO 4) 2·H 2O have been prepared by precipitation of soluble salts of the metals with phosphoric acid and heating the amorphous solids in 12 M H 3PO 4 in an autoclave. The new materials are structurally characterised by Rietveld analysis of synchrotron X-ray powder diffraction data and pair distribution function (PDF) analysis of high energy synchrotron X-ray total scattering data. A broad range of zirconium-titanium phosphate solid solutions were formed showing isomorphous substitution of titanium by zirconium in the ?-titanium phosphate lattice and vice versa for titanium substitution into the ?-zirconium phosphate lattice. In both cases the solubility is partial with the coexistence of two substituted phases observed in samples with nominal compositions between the solubility limits.

Burnell, Victoria A.; Readman, Jennifer E.; Tang, Chiu C.; Parker, Julia E.; Thompson, Stephen P.; Hriljac, Joseph A.

2010-09-01

442

The effect of phosphoric acid concentration on the synthesis of nano-whiskers of calcium metaphosphate by chemical precipitation Method  

NASA Astrophysics Data System (ADS)

Calcium metaphosphate (CMP) nano-whiskers were produced by a chemical precipitation method. In order to produce nano-powders, CMP was prepared by the mixing of two precursors, calcium oxide (CaO) and phosphate acid (H3PO4). Sparingly soluble chemicals, the Ca/P ratio of the mixture was set to be 0.50 to produce stoichiometric CMP, were chemical agitated in phosphate acid solution. At least 3 hours of pre-hydrolysis of phosphorus precursor were required to obtain CMP phase. The CMP powders were dried in a drying oven at 60 °C for 7 days and then followed by a heat treatment at 390 °C for 8hours. The obtained powder was analyzed using XRD, XRF, FT-IR, SEM, TG-DTA, Zeta Potential Meter, Specific Surface Area, and Particle Size Analyzer. The results showed that obtained CMP nano-whiskers have a significantly powder characteristics.

Yao, Nengjian; Zhang, Yin; Kong, Deshuang; Zhu, Jianping; Tao, Yaqiu; Qiu, Tai

2011-10-01

443

Removal of scratch on the surface of MgO single crystal substrate in chemical mechanical polishing process  

NASA Astrophysics Data System (ADS)

Etching and chemical mechanical polishing (CMP) experiments of the MgO single crystal substrate with an artificial scratch on its surface are respectively performed with the developed polishing slurry mainly containing 2 vol.% phosphoric acid (H 3PO 4) and 10-20 nm colloidal silica particles, through observing the variations of the scratch topography on the substrate surface in experiments process, the mechanism and effect of removing scratch during etching and polishing are studied, some evaluating indexes for effect of removing scratch are presented. Finally, chemical mechanical polishing experiments of the MgO substrates after lapped are conducted by using different kinds of polishing pads, and influences of the polishing pad hardness on removal of the scratches on the MgO substrate surface are discussed.

Kang, R. K.; Wang, K.; Wang, J.; Guo, D. M.

2008-05-01

444

Production of activated carbon from bagasse and rice husk by a single-stage chemical activation method at low retention times.  

PubMed

The production of activated carbon from bagasse and rice husk by a single-stage chemical activation method in short retention times (30-60min) was examined in this study. The raw materials were subjected to a chemical pretreatment and were fed to the reactor in the form of a paste (75% moisture). Chemicals examined were ZnCl2, NaOH and H3PO4, for temperatures of 600, 700 and 800 degrees C. Of the three chemical reagents under evaluation only ZnCl2 produced activated carbons with high surface areas. BET surface areas for rice husk were up to 750m2/g for 1:1 ZnCl2:rice husk ratio. BET surface areas for bagasse were up to 674m2/g for 0.75:1 ZnCl2:bagasse ratio. Results were compared to regular two-stage physical activation methods. PMID:18364254

Kalderis, Dimitrios; Bethanis, Sophia; Paraskeva, Panagiota; Diamadopoulos, Evan

2008-10-01

445

Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes  

NASA Astrophysics Data System (ADS)

In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current-voltage measurements. The zero-bias resistance area product R0A above 4 × 105 ? cm2 at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.

Chaghi, R.; Cervera, C.; Aït-Kaci, H.; Grech, P.; Rodriguez, J. B.; Christol, P.

2009-06-01

446

Ab initio calculations of proton transfer in dimethylformamide-phosphoric acid complexes of 1 : 1 composition  

NASA Astrophysics Data System (ADS)

The energy parameters of the reactions that result from adding protons to phosphoric acid, its dimer, and dimethylformamide; the reactions of the formation of phosphoric acid dimers and dimethylformamide-phosphoric acid complexes; and reactions involving the protonated forms of dimethylformamide and acid are calculated by means of DFT B3LYP using the 6-31++G( d, p) basis set. The structural characteristics of the complexes and transitional states are calculated along with the change in energy upon proton transfer. The effect media have on the energy characteristics of proton transfer is studied. It is found the energy barrier of proton transfer grows upon an increase in the O⋯O distance. It is concluded that the lowest energy barriers of proton transfer are expected for DMFH+⋯DMF and H3PO4⋯H2PO{4/-} complexes.

Krestyaninov, M. A.; Kiselev, M. G.; Safonova, L. P.

2015-04-01

447

Titrimetric micro determination of some phenothiazine neuroleptics with potassium hexacyanoferrate(III).  

PubMed

Three simple, rapid and accurate titrimetric procedures using potassium hexacyanoferrate(III) have been developed for the micro determination of five phenothiazine drugs in pure form and in dosage forms. The procedures are based on the oxidation of phenothiazines in an acid medium to colourless sulphoxides via orange or purple coloured products. In the first procedure, phenothiazines are titrated directly in H(2)SO(4)-H(3)PO(4) medium to a colourless end point. In the second method, a known excess of the oxidant is added and after a specified time, the residual oxidant is determined iodometrically. The third method employs electrometric end-point detection. The optimum reactions conditions and other analytical parameters are evaluated. The influence of the substrates commonly employed as excipients with phenothiazine drugs has been studied. Statistical comparison of the results with those of an official method shows excellent agreement and indicates no significant difference in precision. PMID:18967303

Basavaiah, K; Krishnamurthy, G

1998-09-01

448

Influence of activated carbon upon the photocatalytic degradation of methylene blue under UV-vis irradiation.  

PubMed

Photodegradation of methylene blue (MB) was studied on TiO2 in the presence of activated carbon (AC) prepared from the sawdust of a soft wood by physical activation under CO2 flow, by pyrolysis under N2 flow, and by chemical activation with ZnCl2 and H3PO4 under N2 flow. MB photodegradation was performed under UV and UV-visible irradiation to verify the scaling-up of the present TiO2-AC binary materials. It was verified that oxygenated surface groups on carbon were intrinsically photoactive, and a synergy effect between both solids has been estimated from the first-order apparent rate constants in the photodegradation of MB. This effect enhances the photoactivity of TiO2 up to a factor of about 9 under visible irradiation, and it was associated to the surface properties of AC. PMID:24788930

Matos, Juan; Montaña, Ricmary; Rivero, Eliram

2015-01-01

449

Temperature dependence of the electrode kinetics of oxygen reduction at the platinum/Nafion interface - A microelectrode investigation  

NASA Technical Reports Server (NTRS)

Results of a study of the temperature dependence of the oxygen reduction kinetics at the Pt/Nafion interface are presented. This study was carried out in the temperature range of 30-80 C and at 5 atm of oxygen pressure. The results showed a linear increase of the Tafel slope with temperature in the low current density region, but the Tafel slope was found to be independent of temperature in the high current density region. The values of the activation energy for oxygen reduction at the platinum/Nafion interface are nearly the same as those obtained at the platinum/trifluoromethane sulfonic acid interface but less than values obtained at the Pt/H3PO4 and Pt/HClO4 interfaces. The diffusion coefficient of oxygen in Nafion increases with temperature while its solubility decreases with temperature. These temperatures also depend on the water content of the membrane.

Parthasarathy, Arvind; Srinivasan, Supramanian; Appleby, A. J.; Martin, Charles R.

1992-01-01

450

Characterization of native and anodic oxide films formed on commercial pure titanium using electrochemical properties and morphology techniques  

NASA Astrophysics Data System (ADS)

Potentiostatically anodized oxide films on the surface of commercial pure titanium (cp-Ti) formed in sulfuric (0.5 M H 2SO 4) and in phosphoric (1.4 M H 3PO 4) acid solutions under variables anodizing voltages were investigated and compared with the native oxide film. Potentiodynamic polarization and electrochemical impedance spectroscopy, EIS, were used to predicate the different in corrosion behavior of the oxide film samples. Scanning electron microscope, SEM, and electron diffraction X-ray analysis, EDX, were used to investigate the difference in the morphology between different types of oxide films. The electrochemical characteristics were examined in phosphate saline buffer solution, PSB (pH 7.4) at 25 °C. Results have been shown that the nature of the native oxide film is thin and amorphous, while the process of anodization of Ti in both acid solutions plays an important role in changing the properties of passive oxide films. Significant increase in the corrosion resistance of the anodized surface film was recorded after 3 h of electrode immersion in PSB. On the other side, the coverage ( ?) of film formed on cp-Ti was differed by changing the anodized acid solution. Impedance results showed that both the native film and anodized film formed on cp-Ti consist of two layers. The resistance of the anodized film has reached to the highest value by anodization of cp-Ti in H 3PO 4 and the inner layer in the anodized film formed in both acid solutions is also porous.

Fadl-allah, Sahar A.; Mohsen, Q.

2010-08-01

451

Simultaneous separation of eight beta-adrenergic drugs using titanium dioxide nanoparticles as additive in capillary electrophoresis.  

PubMed

The analysis is described for separating seven beta-adrenergic blocking agents (atenolol, celiprolol, clorprenaline, fenoterol, metoprolol, propranolol, terbutaline) and clenbuterol (sympathomimetic beta-2 receptor stimulating agonist, decongestant and bronchodilator, illicit anabolic used in athletics) by CE with UV detection. In order to simultaneously separate all analytes, Tris-H3PO4 solution was applied containing titanium dioxide nanoparticles (TiO2 NPs) as BGEs. The effects of important factors, such as concentration of TiO2 NPs, optimum pH, run buffer concentration, and separation voltage, were investigated so as to achieve best CE separation. The eight analytes could be well separated applying a separation voltage of 15 kV in 75 mM Tris-H3PO4 buffer at a pH of 2.40, containing 6.0 x 10(-6) g/mL TiO2 NPs. Under these optimal conditions, the RSDs for peak areas and for migration times were less than 2.7 and 2.3%, respectively. The detection limits were 0.1 microg/mL for celiprolol, 0.1 microg/mL for propranolol, 0.2 microg/mL for fenoterol, 1.0 microg/mL for atenolol, 1.0 microg/mL for clenbuterol, 1.0 microg/mL for clorprenaline, 1.0 microg/mL for metoprolol, and 1.0 microg/mL for terbutaline. The proposed method was successfully applied for the rapid CE determination of the frequently applied antihypertensive beta-blocking compounds atenolol, metoprolol, terbutaline, and propranolol in pharmaceutical tablets. PMID:18435493

Zhou, Shanshan; Wang, Yanqing; De Beer, Thomas; Baeyens, Willy R G; Fei, Guang Tao; Dilinuer, Malike; Ouyang, Jin

2008-06-01

452

Immobilization of Cu, Pb and Zn in mine-contaminated soils using reactive materials.  

PubMed

Immobilization processes were used to chemically stabilize soil contaminated with Cu, Pb and Zn from mine tailings and industrial impoundments. We examined the effectiveness of ordinary Portland cement (OPC), phosphoric acid and MgO at immobilizing Cu, Pb and Zn in soil contaminated by either mine tailings or industrial and mine wastes. The effectiveness was evaluated using column leaching experiments and geochemical modelling, in which we assessed possible mechanisms for metal immobilization using PHREEQC and Medusa numerical codes. Experimental results showed that Cu was mobilized in all the experiments, whereas Pb immobilization with H(3)PO(4) may have been related to the precipitation of chloropyromorphite. Thus, the Pb concentrations of leachates of pure mining and industrial contaminated soils (32-410 ?g/l and 430-1000 ?g/l, respectively) were reduced to 1-60 and 3-360 ?g/l, respectively, in the phosphoric acid experiment. The mobilization of Pb at high alkaline conditions, when Pb(OH)(4)(-) is the most stable species, may be the main obstacle to the use of OPC and MgO in the immobilization of this metal. In the mining- and industry-contaminated soil, Zn was retained by OPC but removed by MgO. The experiments with OPC showed the Zn decrease in the leachates of mining soil from 226-1960 ?g/l to 92-121 ?g/l. In the industrial contaminated soil, the Zn decrease in the leachates was most elevated, showing >2500 ?g/l in the leachates of contaminated soil and 76-173 ?g/l in the OPC experiment. Finally, when H(3)PO(4) was added, Zn was mobilized. PMID:21190796

Navarro, Andrés; Cardellach, Esteve; Corbella, Mercé

2011-02-28

453

Solid state NMR studies of materials for energy technology  

NASA Astrophysics Data System (ADS)

Presented in this dissertation are NMR investigations of the dynamical and structural properties of materials for energy conversion and storage devices. 1H and 2H NMR was used to study water and methanol transportation in sulfonated poly(arylene ether ketone) based membranes for direct methanol fuel cells (DMFC). These results are presented in chapter 3. The amount of liquid in the membrane and ion exchange capacity (IEC) are two main factors that govern the dynamics in these membranes. Water and methanol diffusion coefficients also are comparable. Chapters 4 and 5 are concerned with 31P and 1H NMR in phosphoric acid doped PBI membranes (para-PBI and 2OH-PBI) as well as PBI membranes containing ionic liquids (H3PO4/PMIH2PO4/PBI). These membranes are designed for higher-temperature fuel cell operation. In general, stronger short and long range interactions were observed in the 2OH-PBI matrix, yielding reduced proton transport compared to that of para-PBI. In the case of H3PO4/PMIH2PO 4/PBI, both conductivity and diffusion are higher for the sample with molar ratio 2/4/1. Finally, chapter 6 is devoted to the 31P NMR MAS study of phosphorus-containing structural groups on the surfaces of micro/mesoporous activated carbons. Two spectral features were observed and the narrow feature identifies surface phosphates while the broad component identifies heterogeneous subsurface phosphorus environments including phosphate and more complex structure multiple P-C, P-N and P=N bonds.

Nambukara Kodiweera Arachchilage, Chandana K.

454

Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage.  

PubMed

Micro-supercapacitors are promising energy storage devices that can complement or even replace batteries in miniaturized portable electronics and microelectromechanical systems. Their main limitation, however, is the low volumetric energy density when compared with batteries. Here, we describe a hierarchically structured carbon microfibre made of an interconnected network of aligned single-walled carbon nanotubes with interposed nitrogen-doped reduced graphene oxide sheets. The nanomaterials form mesoporous structures of large specific surface area (396 m(2) g(-1)) and high electrical conductivity (102 S cm(-1)). We develop a scalable method to continuously produce the fibres using a silica capillary column functioning as a hydrothermal microreactor. The resultant fibres show a specific volumetric capacity as high as 305 F cm(-3) in sulphuric acid (measured at 73.5 mA cm(-3) in a three-electrode cell) or 300 F cm(-3) in polyvinyl alcohol (PVA)/H(3)PO(4) electrolyte (measured at 26.7 mA cm(-3) in a two-electrode cell). A full micro-supercapacitor with PVA/H(3)PO(4) gel electrolyte, free from binder, current collector and separator, has a volumetric energy density of ?6.3 mWh cm(-3) (a value comparable to that of 4 V-500 µAh thin-film lithium batteries) while maintaining a power density more than two orders of magnitude higher than that of batteries, as well as a long cycle life. To demonstrate that our fibre-based, all-solid-state micro-supercapacitors can be easily integrated into miniaturized flexible devices, we use them to power an ultraviolet photodetector and a light-emitting diode. PMID:24813695

Yu, Dingshan; Goh, Kunli; Wang, Hong; Wei, Li; Jiang, Wenchao; Zhang, Qiang; Dai, Liming; Chen, Yuan

2014-07-01

455

Resin–dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding  

PubMed Central

Objective To compare resin–dentin bond strengths and the micropermeability of hydrophobic vs. hydrophilic resins bonded to acid-etched or EDTA-treated dentin, using the ethanol wet-bonding technique. Methods Flat dentin surfaces from extracted human third molars were conditioned before bonding with: 37% H3PO4 (15 s) or 0.1 M EDTA (60 s). Five experimental resin blends of different hydrophilicities and one commercial adhesive (SBMP: Scotchbond Multi-Purpose) were applied to ethanol wet-dentin (1 min) and light-cured (20 s). The solvated resins were used as primers (50% ethanol/50% comonomers) and their respective neat resins were used as the adhesive. The resin-bonded teeth were stored in distilled water (24 h) and sectioned in beams for microtensile bond strength testing. Modes of failure were examined by stereoscopic light microscopy and SEM. Confocal tandem scanning microscopy (TSM) interfacial characterization and micropermeability were also performed after filling the pulp chamber with 1 wt% aqueous rhodamine-B. Results The most hydrophobic resin 1 gave the lowest bond strength values to acid-etched dentin and all beams failed prematurely when the resin was applied to EDTA-treated dentin. Resins 2 and 3 gave intermediate bond strengths to both conditioned substrates. Resin 4, an acidic hydrophilic resin, gave the highest bond strengths to both EDTA-treated and acid-etched dentin. Resin 5 was the only hydrophilic resin showing poor resin infiltration when applied on acid-etched dentin. Significance The ethanol wet-bonding technique may improve the infiltration of most of the adhesives used in this study into dentin, especially when applied to EDTA-treated dentin. The chemical composition of the resin blends was a determining factor influencing the ability of adhesives to bond to EDTA-treated or 37% H3PO4 acid-etched dentin, when using the ethanol wet-bonding technique in a clinically relevant time period. PMID:20074787

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H.; Tay, Franklin R.; Watson, Timothy F.; Osorio, Raquel

2013-01-01

456

[Preparation, characterization and adsorption performance of mesoporous activated carbon with acidic groups].  

PubMed

Mesoporous activated carbons containing acidic groups were prepared with cotton stalk based fiber as raw mate