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Sample records for zirconium nitrates

  1. Determination of zirconium by amperometric titration of excess complexone III with bismuth nitrate at a bismuth electrode

    SciTech Connect

    Kozulina, M.M.; Lepin, Y.K.; Songina, O.A.

    1985-10-01

    Among the various methods for determining zirconium is the amperometric titration of excess EDTA with bismuth nitrate. Such a titration was first used with a dropping mercury electrode. Here the authors investigate the conditions for titrating with a bismuth indicator electrode because a number of difficulties -current oscillation, mercury toxicity -- arise in work with the dropping mercury electrode. It is determined that the bismuth indicator electrode can in fact be used to determine zirconium by inverse amperometric titration of excess EDTA with bismuth nitrate.

  2. Enhancement in gamma ray induced decomposition of zirconium and thorium nitrates in sulfate matrix in solid state

    NASA Astrophysics Data System (ADS)

    Joshi, N. G.; Garg, A. N.

    1994-12-01

    Gamma ray induced decomposition of zirconium and thorium nitrates in sulfate matrices doped with common cation and alkali metal (Na, K) cations at various concentrations has been studied. G(NO? 2) values of the nitrate salt are found to increase with the concentration of the sulfate in the binary mixture. Electron spin resonance (ESR), thermoluminescence (TL) and reflectance spectral studies suggest the formation of radical species SO? 4, SO? 3, O? 3, O? 2; which may be responsible for the energy transfer to nitrate. Efficiency of energy transfer follows the order K2SO4 > Na2SO4 > Zr/Th sulfate. A possible mechanism has been suggested.

  3. [Adsorption Characteristics of Nitrate and Phosphate from Aqueous Solution on Zirconium-Hexadecyltrimethylammonium Chloride Modified Activated Carbon].

    PubMed

    Zheng, Wen-jing; Lin, Jian-wei; Zhan, Yan-hui; Wang, Hong

    2015-06-01

    A novel adsorbent material, i.e., zirconium-cationic surfactant modified activated carbon (ZrSMAC) was prepared by loading zirconium hydroxide and hexadecyltrimethylammonium chloride (CTAC) on activated carbon, and was used as an adsorbent for nitrate and phosphate removal from aqueous solution. The adsorption characteristics of nitrate and phosphate on ZrSMAC from aqueous solution were investigated in batch mode. Results showed that the ZrSMAC was effective for nitrate and phosphate removal from aqueous solution. The pseudo-second-order kinetic model fitted both the nitrate and phosphate kinetic experimental data well. The equilibrium isotherm data of nitrate adsorption onto the ZrSMAC were well fitted to the Langmuir, Dubinin-Radushkevich (D-R) and Freundlich isotherm models. The equilibrium isotherm data of phosphate adsorption onto the ZrSMAC could be described by the Langmuir and,D- R isotherm models. According to the Langmuir isotherm model, the maximum nitrate and phosphate adsorption capacities for the ZrSMAC were 7.58 mg x g(-1) and 10.9 mg x g(-1), respectively. High pH value was unfavorable for nitrate and phosphate adsorption onto the ZrSMAC. The presence of Cl-, HCO3- and SO4(2-) in solution reduced the nitrate and phosphate adsorption capacities for the ZrSMAC. The nitrate adsorption capacity for the ZrSMAC was reduced by the presence of coexisting phosphate in solution, and the phosphate adsorption capacity for the ZrSMAC was also reduced by the presence of coexisting nitrate in solution. About 90% of nitrate adsorbed on the ZrSMAC could be desorbed in 1 mol x L(-1) NaCl solution, and about 78% of phosphate adsorbed on the ZrSMAC could be desorbed in 1 mol x L(-1) NaOH solution. The adsorption mechanism of nitrate on the ZrSMAC included the anion exchange interactions and electrostatic attraction, and the adsorption mechanism of phosphate on the ZrSMAC included the ligand exchange interaction, electrostatic attraction and anion exchange interaction. PMID:26387324

  4. Development of a continuous process for adjusting nitrate, zirconium, and free hydrofluoric acid concentrations in zirconium fuel dissolver product

    SciTech Connect

    Cresap, D.A.; Halverson, D.S.

    1993-04-01

    In the Fluorinel Dissolution Process (FDP) upgrade, excess hydrofluoric acid in the dissolver product must be complexed with aluminum nitrate (ANN) to eliminate corrosion concerns, adjusted with nitrate to facilitate extraction, and diluted with water to ensure solution stability. This is currently accomplished via batch processing in large vessels. However, to accommodate increases in projected throughput and reduce water production in a cost-effective manner, a semi-continuous system (In-line Complexing (ILC)) has been developed. The major conclusions drawn from tests demonstrating the feasibility of this concept are given in this report.

  5. PROCESS OF RECOVERING ZIRCONIUM VALUES FROM HAFNIUM VALUES BY SOLVENT EXTRACTION WITH AN ALKYL PHOSPHATE

    DOEpatents

    Peppard, D.F.

    1960-02-01

    A process of separating hafnium nitrate from zirconium nitrate contained in a nitric acid solution by selectively. extracting the zirconium nitrate with a water-immiscible alkyl phosphate is reported.

  6. Nitrate

    Integrated Risk Information System (IRIS)

    Nitrate ; CASRN 14797 - 55 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

  7. SEPARATION PROCESS FOR ZIRCONIUM AND COMPOUNDS THEREOF

    DOEpatents

    Crandall, H.W.; Thomas, J.R.

    1959-06-30

    The separation of zirconium from columbium, rare earths, yttrium and the alkaline earth metals, such mixtures of elements occurring in zirconium ores or neutron irradiated uranium is described. According to the invention a suitable separation of zirconium from a one normal acidic aqueous solution containing salts, nitrates for example, of tetravalent zirconium, pentavalent columbium, yttrium, rare earths in the trivalent state and alkaline earths can be obtained by contacting the aqueous solution with a fluorinated beta diketonc alone or in an organic solvent solution, such as benzene, to form a zirconium chelate compound. When the organic solvent is present the zirconium chelate compound is directly extracted; otherwise it is separated by filtration. The zirconium may be recovered from contacting the organic solvent solution containing the chelated compound by back extraction with either an aqueous hydrofluoric acid or an oxalic acid solution.

  8. DISSOLUTION OF ZIRCONIUM AND ALLOYS THEREFOR

    DOEpatents

    Swanson, J.L.

    1961-07-11

    The dissolution of zirconium cladding in a water solution of ammonium fluoride and ammonium nitrate is described. The method finds particular utility in processing spent fuel elements for nuclear reactors. The zirconium cladding is first dissolved in a water solution of ammonium fluoride and ammonium nitrate; insoluble uranium and plutonium fiuorides formed by attack of the solvent on the fuel materiai of the fuel element are then separated from the solution, and the fuel materiai is dissolved in another solution.

  9. METHOD OF IMPROVING CORROSION RESISTANCE OF ZIRCONIUM

    DOEpatents

    Shannon, D.W.

    1961-03-28

    An improved intermediate rinse for zirconium counteracts an anomalous deposit that often results in crevices and outof-the-way places when ordinary water is used to rinse away a strong fluoride etching solution designed to promote passivation of the metal. The intermediate rinse, which is used after the etching solution and before the water, is characterized by a complexing agent for fluoride ions such as aluminum or zirconium nitrates or chlorides.

  10. Method for calcining nuclear waste solutions containing zirconium and halides

    DOEpatents

    Newby, Billie J.

    1979-01-01

    A reduction in the quantity of gelatinous solids which are formed in aqueous zirconium-fluoride nuclear reprocessing waste solutions by calcium nitrate added to suppress halide volatility during calcination of the solution while further suppressing chloride volatility is achieved by increasing the aluminum to fluoride mole ratio in the waste solution prior to adding the calcium nitrate.

  11. PLUTONIUM-ZIRCONIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  12. Radiochemical separation of zirconium and hafnium from other radionuclides.

    PubMed

    Hahn, R B

    1972-11-01

    Radiozirconium and radiohafnium may be separated from all other radionuclides except scandium and protactinium by precipitation with mandelic acid from 5-10 M hydrochloric acid, using commercial zirconyl chloride as carrier. Scandium and protactinium are removed by dissolving the precipitate in sodium carbonate, then adding barium nitrate to precipitate barium carbonate which acts as a scavenger. Zirconium mandelate is finally reprecipitated and the sample weighed and counted in this form. The method was checked by analysing commercial zirconyl chloride and standard rock samples for zirconium and hafnium by neutron-activation analysis. PMID:18961201

  13. Nitrate reduction

    DOEpatents

    Dziewinski, Jacek J. (Los Alamos, NM); Marczak, Stanislaw (Los Alamos, NM)

    2000-01-01

    Nitrates are reduced to nitrogen gas by contacting the nitrates with a metal to reduce the nitrates to nitrites which are then contacted with an amide to produce nitrogen and carbon dioxide or acid anions which can be released to the atmosphere. Minor amounts of metal catalysts can be useful in the reduction of the nitrates to nitrites. Metal salts which are formed can be treated electrochemically to recover the metals.

  14. Nitrate and periplasmic nitrate reductases

    PubMed Central

    Sparacino-Watkins, Courtney; Stolz, John F.; Basu, Partha

    2014-01-01

    The nitrate anion is a simple, abundant and relatively stable species, yet plays a significant role in global cycling of nitrogen, global climate change, and human health. Although it has been known for quite some time that nitrate is an important species environmentally, recent studies have identified potential medical applications. In this respect the nitrate anion remains an enigmatic species that promises to offer exciting science in years to come. Many bacteria readily reduce nitrate to nitrite via nitrate reductases. Classified into three distinct types – periplasmic nitrate reductase (Nap), respiratory nitrate reductase (Nar) and assimilatory nitrate reductase (Nas), they are defined by their cellular location, operon organization and active site structure. Of these, Nap proteins are the focus of this review. Despite similarities in the catalytic and spectroscopic properties Nap from different Proteobacteria are phylogenetically distinct. This review has two major sections: in the first section, nitrate in the nitrogen cycle and human health, taxonomy of nitrate reductases, assimilatory and dissimilatory nitrate reduction, cellular locations of nitrate reductases, structural and redox chemistry are discussed. The second section focuses on the features of periplasmic nitrate reductase where the catalytic subunit of the Nap and its kinetic properties, auxiliary Nap proteins, operon structure and phylogenetic relationships are discussed. PMID:24141308

  15. ZIRCONIUM-CLADDING OF THORIUM

    DOEpatents

    Beaver, R.J.

    1961-11-21

    A method of cladding thorium with zirconium is described. The quality of the bond achieved between thorium and zirconium by hot-rolling is improved by inserting and melting a thorium-zirconium alloy foil between the two materials prior to rolling. (AEC)

  16. Process for separating zirconium isotopes

    SciTech Connect

    Chiang, P.T.; Lahoda, E.J.; Burgman, H.A.

    1986-04-22

    A method is described of separating a feed stream consisting essentially of an aqueous solution of a mixture of /sup 90/Zr and /sup 91 to 96/Zr salts selected from group consisting of thiocyanate, nitrate, sulfate, chloride, perchlorate, and mixtures thereof, into two aqueous product streams, each containing both a /sup 90/Zr isotopic portion and a /sup 91 to 96/Zr isotopic portion, but in different ratios. The method consists of: (A) contacting the feed stream with methylisobutyl ketone or an organic water-immiscible solvent containing an extractant medium selected from the group consisting of quaternary ammonium salts, organic phosphonates, organic phosphinates, organic phosphates, organic sulfonates, primary amines, tertiary amines, polyethers, betadiketones, and mixtures thereof, that preferentially extracts one of the isotopic portions, leaving an aqueous raffinate depleted in that isotopic portions and enriched in the other isotopic portion; (B) stripping the organic solvent of its zirconium with an aqueous acidic strip medium to produce a first aqueous product stream; (C) recycling the stripped organic solvent to step (A); (D) evaporating water from a portion of the aqueous raffinate to produce a concentrated aqueous raffinate and a second aqueous product stream; and (E) recycling the concentrated aqueous raffinate to the feed stream.

  17. Electroless deposition process for zirconium and zirconium alloys

    DOEpatents

    Donaghy, R. E.; Sherman, A. H.

    1981-08-18

    A method is disclosed for preventing stress corrosion cracking or metal embrittlement of a zirconium or zirconium alloy container that is to be coated on the inside surface with a layer of a metal such as copper, a copper alloy, nickel, or iron and used for holding nuclear fuel material as a nuclear fuel element. The zirconium material is etched in an etchant solution, desmutted mechanically or ultrasonically, oxidized to form an oxide coating on the zirconium, cleaned in an aqueous alkaline cleaning solution, activated for electroless deposition of a metal layer and contacted with an electroless metal plating solution. This method provides a boundary layer of zirconium oxide between the zirconium container and the metal layer. 1 fig.

  18. Electroless deposition process for zirconium and zirconium alloys

    DOEpatents

    Donaghy, Robert E.; Sherman, Anna H.

    1981-01-01

    A method is disclosed for preventing stress corrosion cracking or metal embrittlement of a zirconium or zirconium alloy container that is to be coated on the inside surface with a layer of a metal such as copper, a copper alloy, nickel, or iron and used for holding nuclear fuel material as a nuclear fuel element. The zirconium material is etched in an etchant solution, desmutted mechanically or ultrasonically, oxidized to form an oxide coating on the zirconium, cleaned in an aqueous alkaline cleaning solution, activated for electroless deposition of a metal layer and contacted with an electroless metal plating solution. This method provides a boundary layer of zirconium oxide between the zirconium container and the metal layer.

  19. Plasma arc melting of zirconium

    SciTech Connect

    Tubesing, P.K.; Korzekwa, D.R.; Dunn, P.S.

    1997-12-31

    Zirconium, like some other refractory metals, has an undesirable sensitivity to interstitials such as oxygen. Traditionally, zirconium is processed by electron beam melting to maintain minimum interstitial contamination. Electron beam melted zirconium, however, does not respond positively to mechanical processing due to its large grain size. The authors undertook a study to determine if plasma arc melting (PAM) technology could be utilized to maintain low interstitial concentrations and improve the response of zirconium to subsequent mechanical processing. The PAM process enabled them to control and maintain low interstitial levels of oxygen and carbon, produce a more favorable grain structure, and with supplementary off-gassing, improve the response to mechanical forming.

  20. Dopaminium nitrate

    PubMed Central

    Gatfaoui, Sofian; Marouani, Houda; Roisnel, Thierry; Dhaouadi, Hassouna

    2014-01-01

    The asymmetric unit of the title salt [systematic name: 2-(3,4-di­hydroxy­phen­yl)ethanaminium nitrate], C8H12NO2 +·NO3 −, contains two independent cations and two independent nitrate anions. The crystal structure consists of discrete nitrate ions stacked in layers parallel to (010). These layers are linked via the dopaminium cations by O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonds, forming a three-dimensional supra­molecular network. PMID:24860376

  1. SEPARATING HAFNIUM FROM ZIRCONIUM

    DOEpatents

    Lister, B.A.J.; Duncan, J.F.; Hutcheon, J.M.

    1956-08-21

    Substantially complete separation of zirconium from hafnium may be obtained by elution of ion exchange material, on which compounds of the elements are adsorbed, with an approximately normal solution of sulfuric acid. Preferably the acid concentration is between 0.8 N amd 1.2 N, amd should not exceed 1.5 N;. Increasing the concentration of sulfate ion in the eluting solution by addition of a soluble sulfate, such as sodium sulfate, has been found to be advantageous. The preferred ion exchange materials are sulfonated polystyrene resins such as Dowex 50,'' and are preferably arranged in a column through which the solutions are passed.

  2. ZIRCONIUM PHOSPHATE ADSORPTION METHOD

    DOEpatents

    Russell, E.R.; Adamson, A.S.; Schubert, J.; Boyd, G.E.

    1958-11-01

    A method is presented for separating plutonium values from fission product values in aqueous acidic solution. This is accomplished by flowing the solutlon containing such values through a bed of zirconium orthophosphate. Any fission products adsorbed can subsequently be eluted by washing the column with a solution of 2N HNO/sub 3/ and O.lN H/sub 3/PO/sub 4/. Plutonium values may subsequently be desorbed by contacting the column with a solution of 7N HNO/sub 3/ .

  3. Modification in band gap of zirconium complexes

    NASA Astrophysics Data System (ADS)

    Sharma, Mayank; Singh, J.; Chouhan, S.; Mishra, A.; Shrivastava, B. D.

    2016-05-01

    The optical properties of zirconium complexes with amino acid based Schiff bases are reported here. The zirconium complexes show interesting stereo chemical features, which are applicable in organometallic and organic synthesis as well as in catalysis. The band gaps of both Schiff bases and zirconium complexes were obtained by UV-Visible spectroscopy. It was found that the band gap of zirconium complexes has been modified after adding zirconium compound to the Schiff bases.

  4. Zirconium extraction into octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide and tributyl phosphate

    SciTech Connect

    Brewer, K.N.; Herbst, R.S.; Todd, T.A.; Christian, J.D.

    1998-07-01

    Classical slope analysis techniques were used to determine the octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and nitrate stoichiometries for the extraction of zirconium by CMPO diluted with diisopropylbenzene (DIPB). The equilibrium constant for the extraction of zirconium by CMPO was also determined using classical slope analysis techniques. The extraction of zirconium by TBP in n-dodecane was used as a control to verify the zirconium species as Zr{sup +4}, and to verify the experimental methodology. Equilibrium [CMPO]{sub org} and [TBP]{sub org} concentrations were determined by accounting for the extraction of HNO{sub 3} into both TBP and CMPO solvents. Nitric acid dissociation and aqueous phase activity coefficients were also taken into consideration. Organic activity coefficients, Zr{sup +4} activity coefficients, Zr{sup +4} hydrolysis, and consumption of TBP or CMPO by water were neglected. Nitrate and CMPO dependencies for the extraction of zirconium have been determined from this work to be: Zr{sub aq}{sup +4} + 4 NO{sub 3 aq}{sup {minus}} + 2 CMPO{sub org} {r_arrow} Zr(NO{sub 3}){sub 4} {sm_bullet} 2 CMPO{sub org}. An equilibrium constant of 1.13 {times} 10{sup 5} {+-} 1.48 {times} 10{sup 4} at 25 C was also determined for this reaction.

  5. Separation of zirconium and uranium. [Patent application

    SciTech Connect

    Henry, H.G.

    1981-05-27

    This invention relates to separation and recovery of zirconium from aqueous solutions containing zirconium and uranium. Separation of zirconium from uranium is, however, difficult since the uranium tends to accompany the zirconium in the solvent extraction and stripping steps. It is therefore desirable, and an object of the invention, to provide a simple and economical way of removing a major portion of the zirconium from the zirconium and uranium-containing strip solutions, with minimal removal of uranium. It has now been found, according to the present invention, that such a removal of zirconium may be accomplished by means of a process involving precipitation of zirconium from such zirconium and uranium-containing feed solutions by means of tartaric acid or a tartrate.

  6. Fine-grained zirconium-base material

    DOEpatents

    Van Houten, G.R.

    1974-01-01

    A method is described for making zirconium with inhibited grain growth characteristics, by the process of vacuum melting the zirconium, adding 0.3 to 0.5% carbon, stirring, homogenizing, and cooling. (Official Gazette)

  7. Ablation Resistant Zirconium and Hafnium Ceramics

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey (Inventor); White, Michael J. (Inventor); Kaufman, Larry (Inventor)

    1998-01-01

    High temperature ablation resistant ceramic composites have been made. These ceramics are composites of zirconium diboride and zirconium carbide with silicon carbide, hafnium diboride and hafnium carbide with silicon carbide and ceramic composites which contain mixed diborides and/or carbides of zirconium and hafnium. along with silicon carbide.

  8. PROCESS OF DISSOLVING ZIRCONIUM ALLOYS

    DOEpatents

    Shor, R.S.; Vogler, S.

    1958-01-21

    A process is described for dissolving binary zirconium-uranium alloys where the uranium content is about 2%. In prior dissolution procedures for these alloys, an oxidizing agent was added to prevent the precipitation of uranium tetrafluoride. In the present method complete dissolution is accomplished without the use of the oxidizing agent by using only the stoichiometric amount or slight excess of HF required by the zirconium. The concentration of the acid may range from 2M to 10M and the dissolution is advatageously carried out at a temperature of 80 deg C.

  9. An inorganic ion-exchanger: zirconium silicomolybdate

    SciTech Connect

    Soliev, L.

    1986-01-01

    The present paper is a continuation of a series of investigations devoted to obtaining and studying inorganic exchangers based on zirconium. Data show that zirconium silicomolybdate is well granulated and has both ion-exchange and oxidation-reduction properties. It was concluded that coprecipitation of zirconium, silicon and molybdenum results in zirconium ''silicomolybdate'' in granulated form, suitable for use in columns. Inestigation of zirconium silicomolybdate by the methods of IR spectroscopy and thermographic analysis has shown that in the synthesis of the sorbent, a heteropolyanion of silicomolybdic acid is formed.

  10. Process for producing zirconium based granules

    SciTech Connect

    Jade, S.S.

    1990-05-22

    This patent describes a process for the production f amorphous zirconium based granules. It comprises: adding about 2--15 wt % of a suitable phase stabilizer to an aqueous solutio, based upon the total weight of ZrO{sub 2} in solution, to produce an aqueous solution having a pH in the range of about 4 to 7 comprising a zirconium based complex and phase stabilizer and thereafter; drying the aqueous solution comprising the zirconium based complex and the phase stabilizer at a temperature below about 180{degrees} C. for a time sufficient to evaporate the aqueous solution thereby forming amorphous zirconium based granules containing the phase stabilizer.

  11. Spectrophotometric determination of zirconium with xylenol orange

    SciTech Connect

    Antepenko, R J

    1982-05-14

    High purity hydride forming metal films are used as hydrogen isotope occluders and function as electrodes in neutron generator tubes. This use of zirconium occluder films requires reliable analytical methods for routine determination of the zirconium film weight in a production environment. In this study, a spectrophotometric method was evaluated for the determination of zirconium films. The method is based upon the formation of a highly colored zirconium complex with xylenol orange in a dilute perchloric acid medium. Dilute hydrofluoric acid is used in this procedure to selectively dissolve the zirconium film off the substrate. A perchloric acid fuming step is used to remove hydrofluoric acid from the solution. The zirconium solutions are depolymerized before complex formation by heating in 2 N perchloric acid. The zirconium complex exhibits a maximum absorbance in 0.2 to 0.3 M perchloric acid at a wavelength of 531 nanometers. Beer's law is obeyed for zirconium concentrations through 2.1 parts per million. Molybdenum, at concentrations equal to zirconium, does not interfere with the xylenol orange method.

  12. Alkali metal nitrate purification

    DOEpatents

    Fiorucci, Louis C. (Hamden, CT); Morgan, Michael J. (Guilford, CT)

    1986-02-04

    A process is disclosed for removing contaminants from impure alkali metal nitrates containing them. The process comprises heating the impure alkali metal nitrates in solution form or molten form at a temperature and for a time sufficient to effect precipitation of solid impurities and separating the solid impurities from the resulting purified alkali metal nitrates. The resulting purified alkali metal nitrates in solution form may be heated to evaporate water therefrom to produce purified molten alkali metal nitrates suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of purified alkali metal nitrates.

  13. Method for preparing hydrous zirconium oxide gels and spherules

    DOEpatents

    Collins, Jack L.

    2003-08-05

    Methods for preparing hydrous zirconium oxide spherules, hydrous zirconium oxide gels such as gel slabs, films, capillary and electrophoresis gels, zirconium monohydrogen phosphate spherules, hydrous zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite sorbent, zirconium monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent having a desired crystallinity, zirconium oxide spherules having suspendable particles homogeneously embedded within to form a composite, hydrous zirconium oxide fiber materials, zirconium oxide fiber materials, hydrous zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, zirconium oxide fiber materials having suspendable particles homogeneously embedded within to form a composite and spherules of barium zirconate. The hydrous zirconium oxide spherules and gel forms prepared by the gel-sphere, internal gelation process are useful as inorganic ion exchangers, catalysts, getters and ceramics.

  14. DISSOLUTION OF ZIRCONIUM-CONTAINING FUEL ELEMENTS

    DOEpatents

    Horn, F.L.

    1961-12-12

    Uranium is recovered from spent uranium fuel elements containing or clad with zirconium. These fuel elements are placed in an anhydrous solution of hydrogen fluoride and nitrogen dioxide. Within this system uranium forms a soluble complex and zirconium forms an insoluble complex. The uranium can then be separated, treated, and removed from solution as uranium hexafluoride. (AEC)

  15. Tracing nitrate in watersheds

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-05-01

    Plants need nitrogen to grow, and nitrate is a common fertilizer ingredient, but high levels of nitrate contamination in drinking water sources can cause health problems. It is generally known that nitrogen flows through watersheds from upslope areas down to streams, but the relationships between upslope soil solution or groundwater nitrate concentrations and stream water nitrate levels—and the ways in which land use changes may alter this relationship—are not fully understood.

  16. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrate and potassium nitrate. 181.33... nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued... potassium nitrite, in the production of cured red meat products and cured poultry products....

  17. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued by the U.S. Department of Agriculture for use as sources...

  18. Method of making crack-free zirconium hydride

    DOEpatents

    Sullivan, Richard W.

    1980-01-01

    Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

  19. Method of etching zirconium diboride

    SciTech Connect

    Heath, L.S.; Kwiatkowski, B.

    1988-03-31

    The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon. This invention relates in general to a method of etching, zirconium diboride(ZrB/sub 2/) and, in particular, to a method of dry etching a thin film of ZrB/sub 2/ that has been deposited onto a substrate and patterned using photolithography. U.S. patent application S.N. 156, 124, filed 16 February, 1988, of Linda S. Heath for Method of Etching Titanium Diboride and assigned to a common assignee and with which this application is copending describes and claims a method of etching titanium diboride with a dry etch. Zirconium diboride, like titanium diboride, TiB/sub 2/, has become of interest in laboratory research because of its resistance to change or degradation at high temperatures. By adjusting the process parameters, one is able to attain etch rates of 67 to 140 A/min for ZrB/sub 2/. This is useful for patterning ZrB/sub 2/ as a diffusion barrier or a Schottky contact to semiconductors. The ZrB/sub 2/ film may be on a GaAs substrate.

  20. Influence of ultrasonic treatment of zirconium-containing solutions on precipitation of basic zirconium sulfate

    SciTech Connect

    Kurdyumov, G.M.; Davydova, I.N.; Sarukhanov, R.G.; Istomin-Kastrovskii, V.V.; Pokhodenko, V.N.

    1988-02-20

    The purpose of this work was to study the influence of ultrasonic (US) treatment of zirconium-containing solutions on the characteristics of hydrolytic precipitation of basic zirconium sulfate (BZS), and also on certain properties of BZS and of the zirconium dioxide obtained from it. It was shown that US treatment of zirconium-containing solutions results in depolymerization of polynuclear Zr(IV) complexes, as the result of which precipitation of basic zirconium sulfate from these solutions is more rapid and more complete. The influence of the conditions of US treatment on the particle size has been demonstrated; it is accordingly possible to obtain zirconium dioxide of regulated degree of dispersion from the precipitates.

  1. Clinical applications of oxidized zirconium.

    PubMed

    Sheth, Neil P; Lementowski, Peter; Hunter, Gordon; Garino, Jonathan P

    2008-01-01

    Total joint arthroplasty is being performed in younger, more active patients, which necessitates improved implant longevity and enhanced component performance. Over the past decade, there has been an increased focus on alternative bearing materials as a potential solution to these issues. Historically, cobalt-chromium has been the material of choice as a bearing surface for both the femoral component in total knee arthroplasty (TKA) and the femoral head articulation in total hip arthroplasty (THA). In recent years, oxidized zirconium (OxZr) has been introduced as a bearing surface with superior resistance to surface roughening, improved frictional characteristics, and excellent biocompatibility as compared with cobalt-chrome. This article demonstrates the use of OxZr as an alternate bearing in the setting of TKA, THA, and hip hemi-arthroplasty based on its biomaterial properties as it applies to polyethylene and native cartilage surface articulation. PMID:18284900

  2. Ageing of zirconium alloy components

    NASA Astrophysics Data System (ADS)

    Chatterjee, S.; Shah, Priti Kotak; Dubey, J. S.

    2008-12-01

    India has two types (pressurized heavy water reactors (PHWRs) and boiling water reactors (BWRs)) of commercial nuclear reactors in operation, in addition to research reactors. Many of the life limiting critical components in these reactors are fabricated from zirconium alloys. The progressive degradation of these components caused by the cumulative exposure of high energy neutron irradiation with increasing period of reactor operation was monitored to assess the degree of ageing. The components/specimens examined included fuel element claddings removed from BWRs, pressure tubes and garter springs removed from PHWRs and calandria tube specimens used in PHWRs. The tests included tension test (for cladding, garter spring), fracture toughness test (for pressure tube), crush test (for garter spring), and measurement of irradiation induced growth (for calandria tube). Results of various tests conducted are presented and applications of the test results are elaborated for residual life estimation/life extension of the components.

  3. Production of nuclear grade zirconium: A review

    NASA Astrophysics Data System (ADS)

    Xu, L.; Xiao, Y.; van Sandwijk, A.; Xu, Q.; Yang, Y.

    2015-11-01

    Zirconium is an ideal material for nuclear reactors due to its low absorption cross-section for thermal neutrons, whereas the typically contained hafnium with strong neutron-absorption is very harmful for zirconium as a fuel cladding material. This paper provides an overview of the processes for nuclear grade zirconium production with emphasis on the methods of Zr-Hf separation. The separation processes are roughly classified into hydro- and pyrometallurgical routes. The known pyrometallurgical Zr-Hf separation methods are discussed based on the following reaction features: redox characteristics, volatility, electrochemical properties and molten salt-metal equilibrium. In the present paper, the available Zr-Hf separation technologies are compared. The advantages and disadvantages as well as future directions of research and development for nuclear grade zirconium production are discussed.

  4. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium... nitrite, with or without sodium or potassium nitrite, in the production of cured red meat products...

  5. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium... nitrite, with or without sodium or potassium nitrite, in the production of cured red meat products...

  6. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium... nitrite, with or without sodium or potassium nitrite, in the production of cured red meat products...

  7. Cylodextrin Polymer Nitrate

    NASA Technical Reports Server (NTRS)

    Kosowski, Bernard; Ruebner, Anja; Statton, Gary; Robitelle, Danielle; Meyers, Curtis

    2000-01-01

    The development of the use of cyclodextrin nitrates as possible components of insensitive, high-energy energetics is outlined over a time period of 12 years. Four different types of cyclodextrin polymers were synthesized, nitrated, and evaluated regarding their potential use for the military and aerospace community. The synthesis of these novel cyclodextrin polymers and different nitration techniques are shown and the potential of these new materials is discussed.

  8. Stark broadening effect and zirconium conflict problem

    NASA Astrophysics Data System (ADS)

    Dimitrijević, Milan S.; Popović, Luka Č.; Milovanović, Nenad

    2001-04-01

    Using the Modified Semiempirical Method we have calculated the electron-impact widths for four singly and doubly ionized zirconium UV lines of astrophysical importance. Using the SYNTH and ATLAS9 codes for stellar atmospheres similar to that of the HgMn star χ Lupi we have synthesized the line profiles and found equivalent widths for these lines. The influence of the Stark broadening effect on abundance determination and its contribution to the so-called ``zirconium conflict'' are discussed. .

  9. Thermochemical nitrate destruction

    DOEpatents

    Cox, John L.; Hallen, Richard T.; Lilga, Michael A.

    1992-01-01

    A method is disclosed for denitrification of nitrates and nitrates present in aqueous waste streams. The method comprises the steps of (1) identifying the concentration nitrates and nitrites present in a waste stream, (2) causing formate to be present in the waste stream, (3) heating the mixture to a predetermined reaction temperature from about 200.degree. C. to about 600.degree. C., and (4) holding the mixture and accumulating products at heated and pressurized conditions for a residence time, thereby resulting in nitrogen and carbon dioxide gas, and hydroxides, and reducing the level of nitrates and nitrites to below drinking water standards.

  10. Field determination of nitrate using nitrate reductase

    SciTech Connect

    Campbell, E.R.; Corrigan, J.S.; Campbell, W.H.

    1997-12-31

    Nitrate is routinely measured in a variety of substrates - water, tissues, soils, and foods - both in the field and in laboratory settings. The most commonly used nitrate test methods involve the reduction of nitrate to nitrite via a copper-cadmium reagent, followed by reaction of the nitrite with the Griess dye reagents. The resulting color is translated into a nitrate concentration by comparison with a calibrated color chart or comparator, or by reading the absorbance in a spectrophotometer. This basic method is reliable and sufficiently sensitive for many applications. However, the cadmium reagent is quite toxic. The trend today is for continued increase in concern for worker health and safety; in addition, there are increasing costs and logistical problems associated with regulatory constraints on transport and disposal of hazardous materials. Some suppliers have substituted a zinc-based reagent powder for the cadmium in an effort to reduce toxicity. We describe here an enzyme-based nitrate detection method as an improvement on the basic Griess method that demonstrates equal or superior sensitivity, superior selectivity, and is more environmentally benign. Comparisons between the enzyme-based method and some standard field test kits being used today are made.

  11. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    SciTech Connect

    Dang, Y. Y.; Bhuiyan, M.S.; Paranthaman, M. P.

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide fi lm to fl ake off. Further studies are needed to defi ne the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  12. Purification of zirconium by electrotransport processing

    SciTech Connect

    Zee, R.H.; Carpenter, G.J.C.; Schmidt, F.A.

    1984-01-01

    To better understand what effects solutes have on the true intrinsic properties of zirconium, it is imperative to first prepare metal of extreme purity. This is of particular importance in their present studies concerning the effects of irradiation on the properties of creep and growth in zirconium. One of the most effective methods of preparing high purity metals is by electrotransport processing at high temperatures. In 1940, DeBoer and Fast reported that oxygen migrated toward the anode in zirconium when a dc current is passed through it at elevated temperatures. This was further substantiated by Claudson. Schmidt et al. measured the electric mobility, diffusivity and effect valence of carbon, nitrogen and oxygen in beta zirconium over the temperature range of 1900 K to 2075 K. It was the purpose of this study to utilize these previously determined electrotransport parameters and high vacuum technology to prepare a small amount of ultrapure zirconium for use in irradiation studies at the Chalk River Nuclear Laboratories.

  13. Synthesis of zirconium oxide nanoparticle by sol-gel technique

    SciTech Connect

    Lim, H. S.; Ahmad, A.; Hamzah, H.

    2013-11-27

    Zirconium oxide nanoparticle is synthesized using sol-gel technique. Various mole ratio of ammonia solution and nitric acid relative to zirconium propoxide is added in the reaction to study the effect on the crystallinity and particle size on zirconium oxide particle. Zirconium oxide synthesized with nitric acid have the smallest particle size under FESEM image and show the increasing formation of crystalline tetragonal phase under XRD diffractogram.

  14. The Chilean nitrate deposits.

    USGS Publications Warehouse

    Ericksen, G.E.

    1983-01-01

    The nitrate deposits in the arid Atacama desert of northern Chile consist of saline-cemented surficial material, apparently formed in and near a playa lake that formerly covered the area. Many features of their distribution and chemical composition are unique. The author believes the principal sources of the saline constituents were the volcanic rocks of late Tertiary and Quaternary age in the Andes and that the nitrate is of organic origin. Possible sources of the nitrate, iodate, perchlorate and chromate are discussed. -J.J.Robertson

  15. Thermochemical nitrate destruction

    DOEpatents

    Cox, J.L.; Hallen, R.T.; Lilga, M.A.

    1992-06-02

    A method is disclosed for denitrification of nitrates and nitrites present in aqueous waste streams. The method comprises the steps of (1) identifying the concentration nitrates and nitrites present in a waste stream, (2) causing formate to be present in the waste stream, (3) heating the mixture to a predetermined reaction temperature from about 200 C to about 600 C, and (4) holding the mixture and accumulating products at heated and pressurized conditions for a residence time, thereby resulting in nitrogen and carbon dioxide gas, and hydroxides, and reducing the level of nitrates and nitrites to below drinking water standards.

  16. Processing fissile material mixtures containing zirconium and/or carbon

    DOEpatents

    Johnson, Michael Ernest; Maloney, Martin David

    2013-07-02

    A method of processing spent TRIZO-coated nuclear fuel may include adding fluoride to complex zirconium present in a dissolved TRIZO-coated fuel. Complexing the zirconium with fluoride may reduce or eliminate the potential for zirconium to interfere with the extraction of uranium and/or transuranics from fission materials in the spent nuclear fuel.

  17. Review of zirconium-zircaloy pyrophoricity

    SciTech Connect

    Cooper, T.D.

    1984-11-01

    Massive zirconium metal scrap can be handled, shipped, and stored with no evidence of combustion or pyrophoricity hazards. Mechanically produced fine scrap such as shavings, turnings, or powders can burn but are not pyrophoric unless the particle diameter is less than 54 ..mu..m. Powders with particle diameters less than 54 ..mu..m can be both pyrophoric and explosive. Pyrophoric powders should be collected and stored underwater or under inert gas cover to reduce the flammability hazard. Opening sealed containers of zirconium stored underwater should be attempted with caution since hydrogen may be present. The factors that influence the ignition temperature have been explored in depth and recommendations are included for the safe handling, shipping, and storage of pyrophoric or flammable zirconium. 29 refs., 5 figs., 6 tabs.

  18. Radiation effects on corrosion of zirconium alloys

    SciTech Connect

    Johnson, A.B. Jr.

    1989-06-01

    From the wide use of zirconium alloys as components in nuclear reactors, has come clear evidence that reactor radiation is a major corrosion parameter. The evidence emerges from comparisons of zirconium alloy corrosion behavior in different reactor types, for example, BWRs versus PWRs and in corresponding reactor loop chemistries; also, oxidation rates differ with location along components such as fuel rods and reactor pressure tubes. In most respects, oxidation effects on power reactor components are paralleled by oxidation behavior on specimens exposed to radiation in reactor loops.

  19. In situ hydrogen loading on zirconium powder.

    PubMed

    Maimaitiyili, Tuerdi; Blomqvist, Jakob; Steuwer, Axel; Bjerkén, Christina; Zanellato, Olivier; Blackmur, Matthew S; Andrieux, Jérôme; Ribeiro, Fabienne

    2015-07-01

    For the first time, various hydride phases in a zirconium-hydrogen system have been prepared in a high-energy synchrotron X-ray radiation beamline and their transformation behaviour has been studied in situ. First, the formation and dissolution of hydrides in commercially pure zirconium powder were monitored in real time during hydrogenation and dehydrogenation, then whole pattern crystal structure analysis such as Rietveld and Pawley refinements were performed. All commonly reported low-pressure phases presented in the Zr-H phase diagram are obtained from a single experimental arrangement. PMID:26134803

  20. Thermochemical nitrate reduction

    SciTech Connect

    Cox, J.L.; Lilga, M.A.; Hallen, R.T.

    1992-09-01

    A series of preliminary experiments was conducted directed at thermochemically converting nitrate to nitrogen and water. Nitrates are a major constituent of the waste stored in the underground tanks on the Hanford Site, and the characteristics and effects of nitrate compounds on stabilization techniques must be considered before permanent disposal operations begin. For the thermochemical reduction experiments, six reducing agents (ammonia, formate, urea, glucose, methane, and hydrogen) were mixed separately with {approximately}3 wt% NO{sub 3}{sup {minus}} solutions in a buffered aqueous solution at high pH (13); ammonia and formate were also mixed at low pH (4). Reactions were conducted in an aqueous solution in a batch reactor at temperatures of 200{degrees}C to 350{degrees}C and pressures of 600 to 2800 psig. Both gas and liquid samples were analyzed. The specific components analyzed were nitrate, nitrite, nitrous oxide, nitrogen, and ammonia. Results of experimental runs showed the following order of nitrate reduction of the six reducing agents in basic solution: formate > glucose > urea > hydrogen > ammonia {approx} methane. Airnmonia was more effective under acidic conditions than basic conditions. Formate was also effective under acidic conditions. A more thorough, fundamental study appears warranted to provide additional data on the mechanism of nitrate reduction. Furthermore, an expanded data base and engineering feasibility study could be used to evaluate conversion conditions for promising reducing agents in more detail and identify new reducing agents with improved performance characteristics.

  1. Structural and electrical properties of zirconium doped yttrium oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Bahari, Ali; Ebrahimzadeh, Masoud; Gholipur, Reza

    2014-04-01

    A synthetic process for the formation of ZrxY1-xOy nanostructures is demonstrated by the reaction of yttrium nitrate hexahydrate with zirconium propoxide. The reactions are carried out at temperature 60°C and pressure 0.1 MPa. The energy dispersive X-ray (EDX) spectroscopy measurements confirm formation of ZrxY1-xOy nanostructures and the presence of carbonate and hydroxide species which are removed after high temperature anneals. It was found that the oxygen pressure during synthesis plays a determinant role on the structural properties of the nanostructure. This effect is further studied by atomic force microscopy (AFM) measurements and scanning electron microscope (SEM), which showed the formation of an isotopically organized structure. X-ray diffraction (XRD) measurement reveals that these changes in the nanostructural efficiency are associated with structural and compositional changes among the substrate. The dielectric constant as measured by the capacitance-voltage (C-V) technique is estimated to be around 39.05. C-V measurements taken at 1 MHz show the maximum capacitance for the Zr0.05Y0.95Oy film. The leakage current densities were below 10-5 A/cm2 for the Zr0.05Y0.95Oy film.

  2. METHOD AND ALLOY FOR BONDING TO ZIRCONIUM

    DOEpatents

    McCuaig, F.D.; Misch, R.D.

    1960-04-19

    A brazing alloy can be used for bonding zirconium and its alloys to other metals, ceramics, and cermets, and consists of 6 to 9 wt.% Ni, 6 to 9 wn~.% Cr, Mo, or W, 0 to 7.5 wt.% Fe, and the balance Zr.

  3. Electrochemical impedance spectroscopic study of passive zirconium

    NASA Astrophysics Data System (ADS)

    Ai, Jiahe; Chen, Yingzi; Urquidi-Macdonald, Mirna; Macdonald, Digby D.

    2008-09-01

    Spent, unreproccessed nuclear fuel is generally contained within the operational fuel sheathing fabricated from a zirconium alloy (Zircaloy 2, Zircaloy 4, or Zirlo) and is then stored in a swimming pool and/or dry storage facilities until permanent disposal in a licensed repository. During this period, which begins with irradiation of the fuel in the reactor during operation, the fuel sheathing is exposed to various, aggressive environments. The objective of the present study was to characterize the nature of the passive film that forms on pure zirconium in contact with an aqueous phase [0.1 M B(OH) 3 + 0.001 M LiOH, pH 6.94] at elevated temperatures (in this case, 250 °C), prior to storage, using electrochemical impedance spectroscopy (EIS) with the data being interpreted in terms of the point defect model (PDM). The results show that the corrosion resistance of zirconium in high temperature, de-aerated aqueous solutions is dominated by the outer layer. The extracted model parameter values can be used in deterministic models for predicting the accumulation of general corrosion damage to zirconium under a wide range of conditions that might exist in some repositories.

  4. Intercalation chemistry of zirconium 4-sulfophenylphosphonate

    SciTech Connect

    Svoboda, Jan; Zima, Vítězslav; Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava

    2013-12-15

    Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4′-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules. - Graphical abstract: Nitrogen-containing organic compounds can be intercalated into the interlayer space of zirconium 4-sulfophenylphosphonate. - Highlights: • Zirconium 4-sulfophenylphosphonate was examined as a host material in intercalation chemistry. • A wide range of nitrogen-containing organic compounds were intercalated. • Possible arrangement of the intercalated species is described.

  5. Superconductivity in zirconium-rhodium alloys

    NASA Technical Reports Server (NTRS)

    Zegler, S. T.

    1969-01-01

    Metallographic studies and transition temperature measurements were made with isothermally annealed and water-quenched zirconium-rhodium alloys. The results clarify both the solid-state phase relations at the Zr-rich end of the Zr-Rh alloy system and the influence upon the superconducting transition temperature of structure and composition.

  6. Zirconium modified nickel-copper alloy

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D. (Inventor)

    1977-01-01

    An improved material for use in a catalytic reactor which reduces nitrogen oxide from internal combustion engines is in the form of a zirconium-modified, precipitation-strengthened nickel-copper alloy. This material has a nominal composition of Ni-30 Cu-0.2 Zr and is characterized by improved high temperature mechanical properties.

  7. International strategic minerals inventory summary report; zirconium

    USGS Publications Warehouse

    Towner, R.R.

    1992-01-01

    Zircon, a zirconium silicate, is currently the most important commercial zirconium-bearing mineral. Baddeleyite, a natural form of zirconia, is less important but has some specific end uses. Both zircon and baddeleyite occur in hard-rock and placer deposits, but at present all zircon production is from placer deposits. Most baddeleyite production is from hard-rock deposits, principally as a byproduct of copper and phosphate-rock mining. World zirconium resources in identified, economically exploitable deposits are about 46 times current production rates. Of these resources, some 71 percent are in South Africa, Australia, and the United States. The principal end uses of zirconium minerals are in ceramic applications and as refractories, abrasives, and mold linings in foundries. A minor amount, mainly of zircon, is used for the production of hafnium-free zirconium metal, which is used principally for sheathing fuel elements in nuclear reactors and in the chemical-processing industry, aerospace engineering, and electronics. Australia and South Africa are the largest zircon producers and account for more than 70 percent of world output; the United States and the Soviet Union account for another 20 percent. South Africa accounts for almost all the world's production of baddeleyite, which is about 2 percent of world production of contained zirconia. Australia and South Africa are the largest exporters of zircon. Unless major new deposits are developed in countries that have not traditionally produced zircon, the pattern of world production is unlikely to change by 2020. The proportions, however, of production that come from existing producing countries may change somewhat.

  8. Electrospun cellulose nitrate nanofibers.

    PubMed

    Nartker, Steven; Drzal, Lawrence T

    2010-09-01

    Cellulose nitrate nonwoven mats of submicron-sized fibers (100-1200 nm in diameter) were obtained by electrospinning cellulose nitrate solutions. Two solvent systems were evaluated. A 70:30 (wt) ratio of ethanol to acetone and a 60:40 (wt) ratio of tetrahydrofuran (THF) to N,N-dimethylformamide (DMF) were studied. The effects of the two solvent systems, and type two different collectors; void gap, and steel drum coated with polyvinylidene dichloride (PVDC), were investigated. The PVDC layer applied to the rotating drum aided in fiber harvesting. Electron microscopy (FESEM and ESEM) studies of as-spun fibers revealed that the morphology of cellulose nitrate fibers depended on the collector type and solution viscosity. When a rotating steel drum was employed a random morphology was observed, while the void gap collector produced aligned fiber mats. Increases in viscosity lead to larger diameter fibers. PMID:21133109

  9. Intercalation chemistry of zirconium 4-sulfophenylphosphonate

    NASA Astrophysics Data System (ADS)

    Svoboda, Jan; Zima, Vt?zslav; Melnov, Klra; Bene, Ludvk; Trchov, Miroslava

    2013-12-01

    Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4?-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules.

  10. METHOD OF MAKING DELTA ZIRCONIUM HYDRIDE MONOLITHIC MODERATOR PIECES

    DOEpatents

    Vetrano, J.B.

    1962-01-23

    A method is given for preparing large, sound bodies of delta zirconium hydride. The method includes the steps of heating a zirconium body to a temperature of not less than l000 deg C, providing a hydrogen atmosphere for the zirconium body at a pressure not greater than one atmosphere, reducing the temperature slowly to 800 deg C at such a rate that cracks do not form while maintaining the hydrogen pressure substantially constant, and cooling in an atmosphere of hydrogen. (AEC)

  11. ELECTROLYTIC CLADDING OF ZIRCONIUM ON URANIUM

    DOEpatents

    Wick, J.J.

    1959-09-22

    A method is presented for coating uranium with zircoalum by rendering the uranium surface smooth and oxidefree, immersing it in a molten electrolytic bath in NaCI, K/sub 2/ZrF/sub 6/, KF, and ZrO/sub 2/, and before the article reaches temperature equilibrium with the bath, applying an electrolyzing current of 60 amperes per square dectmeter at approximately 3 volts to form a layer of zirconium metal on the uranium.

  12. Manufacturing process to reduce large grain growth in zirconium alloys

    DOEpatents

    Rosecrans, P.M.

    1984-08-01

    It is an object of the present invention to provide a procedure for desensitizing zirconium-based alloys to large grain growth (LGG) during thermal treatment above the recrystallization temperature of the alloy. It is a further object of the present invention to provide a method for treating zirconium-based alloys which have been cold-worked in the range of 2 to 8% strain to reduce large grain growth. It is another object of the present invention to provide a method for fabricating a zirconium alloy clad nuclear fuel element wherein the zirconium clad is resistant to large grain growth.

  13. The thermal stability of surface deformed zirconium

    NASA Astrophysics Data System (ADS)

    Hayes, T. A.; Kassner, M. E.; Amick, D.; Rosen, R. S.

    1997-07-01

    This study examined the microstructural and mechanical changes in shot-peened zirconium resulting from extended exposures to temperatures between 200 and 300°C. The peening hardens the surface region which extends to about 300 μm from the surface. It was discovered that the outermost (10-50 μm) shot-peened surface decreases in hardness from approximately 230 VHN (DPH) to about 220 VHN after 560 h at 200°C. The same drop in hardness was observed after about 5.5 h at 300°C. Further drops in hardness with time were observed at 300°C to a minimum surface hardness of 206 VHN after 560 h. Longer times at 200 and 300°C did not appear to significantly affect the hardness. These decreases in hardness were determined from hardness depth profiles before and after heat treating the zirconium to various times from 0.5 to 4458 h. The hardness between 150 and 300 μ (the less deformed region) was approximately unaffected by the thermal treatments. The grain dislocation structure of the shot-peened zirconium was examined in the as-peened as well as the annealed conditions using polarized light optical and transmission electron microscopy. These observations are consistent with an explanation of decreased hardness based on static recovery without any static recrystallization.

  14. High temperature behavior of zirconium germanates

    SciTech Connect

    Utkin, A.V.; Baklanova, N.I.; Vasilyeva, I.G.

    2013-05-01

    The high temperature behavior of zirconium germanates ZrGeO₄ and Zr₃GeO₈ up to 2300 °C has been studied using the original photoemission thermal analysis technique with the comprehensive physicochemical study of solid and gaseous intermediate and final products. The two-stage process of incongruent sublimation of GeO₂ was established and the phase boundary of the homogeneity range for ZrGeO₄ and Zr₃GeO₈ were deduced from the thermal analysis, X-ray diffraction and Raman spectroscopy studies. A high tendency to sintering of the final ZrO₂ product is discussed. - Graphical abstract: The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂ and occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. Highlights: •Thermal behavior of ZrGeO₄ and Zr₃GeO₈ was studied using the original thermal analysis technique in wide temperature range. •The decomposition occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. •The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂. •The temperature of decomposition is strongly depended on the total gas pressure.

  15. Fluorometric determination of zirconium in minerals

    USGS Publications Warehouse

    Alford, W.C.; Shapiro, L.; White, C.E.

    1951-01-01

    The increasing use of zirconium in alloys and in the ceramics industry has created renewed interest in methods for its determination. It is a common constituent of many minerals, but is usually present in very small amounts. Published methods tend to be tedious, time-consuming, and uncertain as to accuracy. A new fluorometric procedure, which overcomes these objections to a large extent, is based on the blue fluorescence given by zirconium and flavonol in sulfuric acid solution. Hafnium is the only element that interferes. The sample is fused with borax glass and sodium carbonate and extracted with water. The residue is dissolved in sulfuric acid, made alkaline with sodium hydroxide to separate aluminum, and filtered. The precipitate is dissolved in sulfuric acid and electrolysed in a Melaven cell to remove iron. Flavonol is then added and the fluorescence intensity is measured with a photo-fluorometer. Analysis of seven standard mineral samples shows excellent results. The method is especially useful for minerals containing less than 0.25% zirconium oxide.

  16. Interfacial reactions of zirconium and zirconium-alloy liquid metals with beryllia at elevated temperatures.

    SciTech Connect

    McDeavitt, S. M.; Billings, G. W.; Indacochea, J. E.; Chemical Engineering; Integrated Thermal Sciences, Inc.; Univ. of Illinois at Chicago

    2002-09-01

    Argonne National Laboratory and Integrated Thermal Sciences, Inc. are developing crucible materials for melting reactive metals. A major part of this effort involves identifying reusable materials because they would have little or no interaction with the molten metals at elevated temperatures. Sessile drop-type experiments have been performed using pure zirconium and stainless steel-zirconium alloys (e.g., HT9-15Zr) on beryllia (BeO) substrates. The system was heated in high-purity argon to about 2000{sup o}C, held for 5 minutes, and cooled to room temperature. An external video camera monitored the interfacial interaction and wetting behavior. The zirconium melted and wetted the BeO at 1600{sup o}C, far below its melting point (1855{sup o}C). Post-test examinations show beryllium and oxygen dissolving in the zirconium metal. In addition, zirconium infiltrated the BeO substrate. No third phase reaction product was present at the zirconium-beryllia interface either at the top of the substrate or in the infiltrated region. HT9-15Zr also reacted with BeO; the alloy infiltrated partially into the BeO and formed a reaction-like layer attached to the ceramic substrate at the interface with the solidified metal. The rest of the liquid metal alloy did not wet the reaction product band. The results indicate that BeO is a poor crucible for the present application, but the observed wetting and infiltration phenomena are relevant to understanding the behavior of the liquid metal-ceramic interfaces.

  17. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., described and defined as an oxidizer by the regulations of 49 CFR part 173 is handled, stored, stowed...) must be eliminated or plugged. Note: See 49 CFR 176.415 for permit requirements for nitro carbo nitrate... nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section...

  18. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., described and defined as an oxidizer by the regulations of 49 CFR part 173 is handled, stored, stowed...) must be eliminated or plugged. Note: See 49 CFR 176.415 for permit requirements for nitro carbo nitrate... nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section...

  19. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., described and defined as an oxidizer by the regulations of 49 CFR part 173 is handled, stored, stowed...) must be eliminated or plugged. Note: See 49 CFR 176.415 for permit requirements for nitro carbo nitrate... nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section...

  20. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., described and defined as an oxidizer by the regulations of 49 CFR part 173 is handled, stored, stowed...) must be eliminated or plugged. Note: See 49 CFR 176.415 for permit requirements for nitro carbo nitrate... nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section...

  1. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., described and defined as an oxidizer by the regulations of 49 CFR part 173 is handled, stored, stowed...) must be eliminated or plugged. Note: See 49 CFR 176.415 for permit requirements for nitro carbo nitrate... nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section...

  2. Purification of alkali metal nitrates

    DOEpatents

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

    A process is disclosed for removing heavy metal contaminants from impure alkali metal nitrates containing them. The process comprises mixing the impure nitrates with sufficient water to form a concentrated aqueous solution of the impure nitrates, adjusting the pH of the resulting solution to within the range of between about 2 and about 7, adding sufficient reducing agent to react with heavy metal contaminants within said solution, adjusting the pH of the solution containing reducing agent to effect precipitation of heavy metal impurities and separating the solid impurities from the resulting purified aqueous solution of alkali metal nitrates. The resulting purified solution of alkali metal nitrates may be heated to evaporate water therefrom to produce purified molten alkali metal nitrate suitable for use as a heat transfer medium. If desired, the purified molten form may be granulated and cooled to form discrete solid particles of alkali metal nitrates.

  3. Ammonium nitrate explosive systems

    DOEpatents

    Stinecipher, Mary M.; Coburn, Michael D.

    1981-01-01

    Novel explosives which comprise mixtures of ammonium nitrate and an ammonium salt of a nitroazole in desired ratios are disclosed. A preferred nitroazole is 3,5-dinitro-1,2,4-triazole. The explosive and physical properties of these explosives may readily be varied by the addition of other explosives and oxidizers. Certain of these mixtures have been found to act as ideal explosives.

  4. Nitrate Storage and Dissimilatory Nitrate Reduction by Eukaryotic Microbes

    PubMed Central

    Kamp, Anja; Høgslund, Signe; Risgaard-Petersen, Nils; Stief, Peter

    2015-01-01

    The microbial nitrogen cycle is one of the most complex and environmentally important element cycles on Earth and has long been thought to be mediated exclusively by prokaryotic microbes. Rather recently, it was discovered that certain eukaryotic microbes are able to store nitrate intracellularly and use it for dissimilatory nitrate reduction in the absence of oxygen. The paradigm shift that this entailed is ecologically significant because the eukaryotes in question comprise global players like diatoms, foraminifers, and fungi. This review article provides an unprecedented overview of nitrate storage and dissimilatory nitrate reduction by diverse marine eukaryotes placed into an eco-physiological context. The advantage of intracellular nitrate storage for anaerobic energy conservation in oxygen-depleted habitats is explained and the life style enabled by this metabolic trait is described. A first compilation of intracellular nitrate inventories in various marine sediments is presented, indicating that intracellular nitrate pools vastly exceed porewater nitrate pools. The relative contribution by foraminifers to total sedimentary denitrification is estimated for different marine settings, suggesting that eukaryotes may rival prokaryotes in terms of dissimilatory nitrate reduction. Finally, this review article sketches some evolutionary perspectives of eukaryotic nitrate metabolism and identifies open questions that need to be addressed in future investigations. PMID:26734001

  5. PROCESS FOR DISSOLVING BINARY URANIUM-ZIRCONIUM OR ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Jonke, A.A.; Barghusen, J.J.; Levitz, N.M.

    1962-08-14

    A process of dissolving uranium-- zirconium and zircaloy alloys, e.g. jackets of fuel elements, with an anhydrous hydrogen fluoride containing from 10 to 32% by weight of hydrogen chloride at between 400 and 450 deg C., preferably while in contact with a fluidized inert powder, such as calcium fluoride is described. (AEC)

  6. 40 CFR 721.10602 - Lead niobium titanium zirconium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lead niobium titanium zirconium oxide... Specific Chemical Substances § 721.10602 Lead niobium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead niobium...

  7. 40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead...

  8. 40 CFR 721.10598 - Lead strontium titanium zirconium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lead strontium titanium zirconium... Specific Chemical Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead...

  9. 40 CFR 721.10601 - Lanthanum lead titanium zirconium oxide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Lanthanum lead titanium zirconium... Specific Chemical Substances § 721.10601 Lanthanum lead titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lanthanum...

  10. 40 CFR 721.10601 - Lanthanum lead titanium zirconium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lanthanum lead titanium zirconium... Specific Chemical Substances § 721.10601 Lanthanum lead titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lanthanum...

  11. 40 CFR 721.10602 - Lead niobium titanium zirconium oxide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Lead niobium titanium zirconium oxide... Specific Chemical Substances § 721.10602 Lead niobium titanium zirconium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lead niobium...

  12. Electronic structure and charge density of zirconium diboride

    NASA Astrophysics Data System (ADS)

    Switendick, Alfred C.

    1991-07-01

    Self-consistent calculations of the electronic band structure of zirconium diboride, ZrB2, have been performed. The total and individual band charge densities are analyzed in terms of their site (zirconium or boron) symmetry and plotted. The total charge density shows very little charge asymmetry about either site.

  13. Electronic structure and charge density of zirconium diboride

    SciTech Connect

    Switendick, A.C.

    1990-01-01

    Self-consistent calculations of the electronic band structure of zirconium diboride, ZrB{sub 2}, have been performed. The total and individual band charge densities are analysed in terms of their site (zirconium or boron) symmetry and plotted. The total charge density shows very little charge asymmetry about either site. 6 refs., 6 figs., 37 tabs.

  14. Electronic structure and charge density of zirconium diboride

    SciTech Connect

    Switendick, A.C. )

    1991-07-01

    Self-consistent calculations of the electronic band structure of zirconium diboride, ZrB{sub 2}, have been performed. The total and individual band charge densities are analyzed in terms of their site (zirconium or boron) symmetry and plotted. The total charge density shows very little charge asymmetry about either site.

  15. NEUTRON REACTOR FUEL ELEMENT UTILIZING ZIRCONIUM-BASE ALLOYS

    DOEpatents

    Saller, H.A.; Keeler, J.R.; Szumachowski, E.R.

    1957-11-12

    This patent relates to clad fuel elements for use in neutronic reactors and is drawn to such a fuel element which consists of a core of fissionable material, comprised of an alloy of zirconium and U/sup 235/ enriched uranium, encased in a jacket of a binary zirconium-tin alloy in which the tin content ranges between 1 and 15% by weight.

  16. [The clinical application of zirconium-dioxide-ceramics. Case report].

    PubMed

    Somfai, Dóra; Zsigmond, Ágnes; Károlyházy, Katalin; Kispély, Barbara; Hermann, Péter

    2015-12-01

    Due to its outstanding physical, mechanical and esthetic properties, zirconium-dioxide is one of the most popular non-metal denture, capable of surpassing PFM in most cases. The recent advances of CAD/CAM technology makes it a good alternitve. Here we show the usefulness of zirconium-dioxide in everyday dental practice through three case reports. PMID:26863816

  17. Uranium-preextraction in zirconium/hafnium separations processs

    SciTech Connect

    Feuling, R.J.

    1990-04-03

    This patent describes an improvement in a process for recovering zirconium values from uranium containing zircon ore. The process comprising a fluidized bed carbochlorination of the zircon ore at 800{degrees}--1250{degrees} C., producing a relatively impure, hafnium-containing zirconium tetrachloride stream and by-product silicon tetrachloride, which silicon tetrachloride by-product is separated by differential condensation, and wherein uranium chloride is volatilized at the ore chlorinator temperature and follows as an impurity in the zirconium-hafnium tetrachloride stream, mixing the zirconium-hafnium tetrachloride with water to produce a zirconium-hafnium oxychloride solution, and removing iron impurities by liquid--liquid iron extraction with a methyl isobutyl ketone extractant.

  18. Zirconium fluoride glass - Surface crystals formed by reaction with water

    NASA Technical Reports Server (NTRS)

    Doremus, R. H.; Bansal, N. P.; Bradner, T.; Murphy, D.

    1984-01-01

    The hydrated surfaces of a zirconium barium fluoride glass, which has potential for application in optical fibers and other optical elements, were observed by scanning electron microscopy. Crystalline zirconium fluoride was identified by analysis of X-ray diffraction patterns of the surface crystals and found to be the main constituent of the surface material. It was also found that hydrated zirconium fluorides form only in highly acidic fluoride solutions. It is possible that the zirconium fluoride crystals form directly on the glass surface as a result of its depletion of other ions. The solubility of zirconium fluoride is suggested to be probably much lower than that of barium fluoride (0.16 g/100 cu cm at 18 C). Dissolution was determined to be the predominant process in the initial stages of the reaction of the glass with water. Penetration of water into the glass has little effect.

  19. Nitrate biosensors and biological methods for nitrate determination.

    PubMed

    Sohail, Manzar; Adeloju, Samuel B

    2016-06-01

    The inorganic nitrate (NO3‾) anion is present under a variety of both natural and artificial environmental conditions. Nitrate is ubiquitous within the environment, food, industrial and physiological systems and is mostly present as hydrated anion of a corresponding dissolved salt. Due to the significant environmental and toxicological effects of nitrate, its determination and monitoring in environmental and industrial waters are often necessary. A wide range of analytical techniques are available for nitrate determination in various sample matrices. This review discusses biosensors available for nitrate determination using the enzyme nitrate reductase (NaR). We conclude that nitrate determination using biosensors is an excellent non-toxic alternative to all other available analytical methods. Over the last fifteen years biosensing technology for nitrate analysis has progressed very well, however, there is a need to expedite the development of nitrate biosensors as a suitable alternative to non-enzymatic techniques through the use of different polymers, nanostructures, mediators and strategies to overcome oxygen interference. PMID:27130094

  20. In situ hydrogen loading on zirconium powder

    PubMed Central

    Maimaitiyili, Tuerdi; Blomqvist, Jakob; Steuwer, Axel; Bjerkén, Christina; Zanellato, Olivier; Blackmur, Matthew S.; Andrieux, Jérôme; Ribeiro, Fabienne

    2015-01-01

    For the first time, various hydride phases in a zirconium–hydrogen system have been prepared in a high-energy synchrotron X-ray radiation beamline and their transformation behaviour has been studied in situ. First, the formation and dissolution of hydrides in commercially pure zirconium powder were monitored in real time during hydrogenation and dehydrogenation, then whole pattern crystal structure analysis such as Rietveld and Pawley refinements were performed. All commonly reported low-pressure phases presented in the Zr–H phase diagram are obtained from a single experimental arrangement. PMID:26134803

  1. ZIRCONIUM-TITANIUM-BERYLLIUM BRAZING ALLOY

    DOEpatents

    Gilliland, R.G.; Patriarca, P.; Slaughter, G.M.; Williams, L.C.

    1962-06-12

    A new and improved ternary alloy is described which is of particular utility in braze-bonding parts made of a refractory metal selected from Group IV, V, and VI of the periodic table and alloys containing said metal as a predominating alloying ingredient. The brazing alloy contains, by weight, 40 to 50 per cent zirconium, 40 to 50 per cent titanium, and the balance beryllium in amounts ranging from 1 to 20 per cent, said alloy having a melting point in the range 950 to 1400 deg C. (AEC)

  2. Shell model description of zirconium isotopes

    SciTech Connect

    Sieja, K.; Nowacki, F.; Langanke, K.; Martinez-Pinedo, G.

    2009-06-15

    We calculate the low-lying spectra and several high-spin states of zirconium isotopes (Z=40) with neutron numbers from N=50 to N=58 using a large valence space with the {sup 78}Ni inert core, which a priori allows one to study the interplay between spherical and deformed configurations, necessary for the description of nuclides in this part of the nuclear chart. The effective interaction is derived by monopole corrections of the realistic G matrix. We reproduce essential nuclear properties, such as subshell closures in {sup 96}Zr and {sup 98}Zr. The spherical-to-deformed shape transition in {sup 100}Zr is addressed as well.

  3. Diffusion of hydrogen in zirconium foil

    SciTech Connect

    Schur, D.V.; Pishuk, V.K.; Adejev, V.M.; Zaginaichenko, S.Y.

    1998-12-31

    The authors of present research have used in experiments the atomic hydrogen and metallic foil 25--30 {micro}m thick. It has been supposed that these technical operations will permit excluding the influence of surface and diffusional processes on the rate of Me-H interaction. The series of experiments have been carried out and they confirm this assumption. It has been shown that hydrogenation reaction of zirconium foil in atomic hydrogen conforms to the topochemical model of volume segregation of interaction product, and the rate of its flow is independent of the surface processes and hydrogen diffusion in volume.

  4. Assimilation of nitrate by yeasts.

    PubMed

    Siverio, José M

    2002-08-01

    Nitrate assimilation has received much attention in filamentous fungi and plants but not so much in yeasts. Recently the availability of classical genetic and molecular biology tools for the yeast Hansenula polymorpha has allowed the advance of the study of this metabolic pathway in yeasts. The genes YNT1, YNR1 and YNI1, encoding respectively nitrate transport, nitrate reductase and nitrite reductase, have been cloned, as well as two other genes encoding transcriptional regulatory factors. All these genes lie closely together in a cluster. Transcriptional regulation is the main regulatory mechanism that controls the levels of the enzymes involved in nitrate metabolism although other mechanisms may also be operative. The process involved in the sensing and signalling of the presence of nitrate in the medium is not well understood. In this article the current state of the studies of nitrate assimilation in yeasts as well as possible venues for future research are reviewed. PMID:12165428

  5. dl-Asparaginium nitrate.

    PubMed

    Moussa Slimane, Nabila; Cherouana, Aouatef; Bendjeddou, Lamia; Dahaoui, Slimane; Lecomte, Claude

    2009-01-01

    In the title compound, C(4)H(9)N(2)O(3) (+)·NO(3) (-), alternatively called (1RS)-2-carbamoyl-1-carboxy-ethanaminium nitrate, the asymmetric unit comprises one asparaginium cation and one nitrate anion. The strongest cation-cation O-H⋯O hydrogen bond in the structure, together with other strong cation-cation N-H⋯O hydrogen bonds, generates a succession of infinite chains of R(2) (2)(8) rings along the b axis. Additional cation-cation C-H⋯O hydrogen bonds link these chains into two-dimensional layers formed by alternating R(4) (4)(24) and R(4) (2)(12) rings. Connections between these layers are provided by the strong cation-anion N-H⋯O hydrogen bonds, as well as by one weak C-H⋯O inter-action, thus forming a three-dimensional network. Some of the cation-anion N-H⋯O hydrogen bonds are bifurcated of the type D-H⋯(A(1),A(2)). PMID:21577586

  6. dl-Asparaginium nitrate

    PubMed Central

    Moussa Slimane, Nabila; Cherouana, Aouatef; Bendjeddou, Lamia; Dahaoui, Slimane; Lecomte, Claude

    2009-01-01

    In the title compound, C4H9N2O3 +·NO3 −, alternatively called (1RS)-2-carbamoyl-1-carboxy­ethanaminium nitrate, the asymmetric unit comprises one asparaginium cation and one nitrate anion. The strongest cation–cation O—H⋯O hydrogen bond in the structure, together with other strong cation–cation N—H⋯O hydrogen bonds, generates a succession of infinite chains of R 2 2(8) rings along the b axis. Additional cation–cation C—H⋯O hydrogen bonds link these chains into two-dimensional layers formed by alternating R 4 4(24) and R 4 2(12) rings. Connections between these layers are provided by the strong cation–anion N—H⋯O hydrogen bonds, as well as by one weak C—H⋯O inter­action, thus forming a three-dimensional network. Some of the cation–anion N—H⋯O hydrogen bonds are bifurcated of the type D—H⋯(A 1,A 2). PMID:21577586

  7. Protein nitration in cardiovascular diseases.

    PubMed

    Turko, Illarion V; Murad, Ferid

    2002-12-01

    There is growing evidence that cardiovascular disease is associated with progressive changes in the production of free radicals and radical-derived reactive species. These intermediates react with all major cellular constituents and may serve several physiological and pathophysiological functions. The nitration of protein tyrosine residues has been used as a footprint for in vivo production of radical and nonradical reactive species. Tyrosine nitration may alter protein function and metabolism and therefore, provides for further dysfunctional changes. This review focuses on an appearance of tyrosine nitrated proteins in cardiovascular tissues under different settings of cardiovascular disease. Sources of reactive species, putative mechanisms of protein nitration in vivo, as well as protein nitration under normal physiological conditions, are also described. The goal of this review is to attract more attention to identification of specific proteins, which undergo tyrosine nitration and to study a correlation between their altered function and pathology. Understanding how protein nitration affects disease progression may offer a unique option for design of antioxidant therapy for the treatment of cardiovascular complications. At the same time, protein nitration can be a biological marker of efficiency of antioxidant therapy. PMID:12429871

  8. Evaluation of nitrate destruction methods

    SciTech Connect

    Taylor, P.A.; Kurath, D.E.; Guenther, R.

    1993-03-30

    A wide variety of high nitrate-concentration aqueous mixed [radioactive and Resource Conservation and Recovery Act (RCRA) hazardous] wastes are stored at various US Department of Energy (DOE) facilities. These wastes will ultimately be solidified for final disposal, although the waste acceptance criteria for the final waste form is still being determined. Because the nitrates in the wastes will normally increase the volume or reduce the integrity of all of the waste forms under consideration for final disposal, nitrate destruction before solidification of the waste will generally be beneficial. This report describes and evaluates various technologies that could be used to destroy the nitrates in the stored wastes. This work was funded by the Department of Energy`s Office of Technology Development, through the Chemical/Physical Technology Support Group of the Mixed Waste Integrated Program. All the nitrate destruction technologies will require further development work before a facility could be designed and built to treat the majority of the stored wastes. Several of the technologies have particularly attractive features: the nitrate to ammonia and ceramic (NAC) process produces an insoluble waste form with a significant volume reduction, electrochemical reduction destroys nitrates without any chemical addition, and the hydrothermal process can simultaneously treat nitrates and organics in both acidic and alkaline wastes. These three technologies have been tested using lab-scale equipment and surrogate solutions. At their current state of development, it is not possible to predict which process will be the most beneficial for a particular waste stream.

  9. Crystal Structure of the ZrO Phase at Zirconium/Zirconium Oxide Interfaces**

    PubMed Central

    Nicholls, Rebecca J; Ni, Na; Lozano-Perez, Sergio; London, Andrew; McComb, David W; Nellist, Peter D; Grovenor, Chris RM; Pickard, Chris J; Yates, Jonathan R

    2015-01-01

    Zirconium-based alloys are used in water-cooled nuclear reactors for both nuclear fuel cladding and structural components. Under this harsh environment, the main factor limiting the service life of zirconium cladding, and hence fuel burn-up efficiency, is water corrosion. This oxidation process has recently been linked to the presence of a sub-oxide phase with well-defined composition but unknown structure at the metal–oxide interface. In this paper, the combination of first-principles materials modeling and high-resolution electron microscopy is used to identify the structure of this sub-oxide phase, bringing us a step closer to developing strategies to mitigate aqueous oxidation in Zr alloys and prolong the operational lifetime of commercial fuel cladding alloys. PMID:25892957

  10. Ballistic effectiveness of superdense solid composite propellants with zirconium or zirconium hydride

    NASA Astrophysics Data System (ADS)

    Lempert, D.; Manelis, G.; Nechiporenko, G.

    2011-10-01

    The ballistic effectiveness of propellants depends not only on the value of specific impulse but also on many other performances, primarily on the density. Despite the density itself does not enter the expression of the rocket velocity (W = Isp ln(Mlaunch/Mfinish) where Mlaunch and Mfinish are the rocket launch mass and its mass after the propellant is burnt, respectively), it in§uences the value Mlaunch/Mfinish of the specific rocket. If one charges the construction of fixed volume with a more dense propellant, the ratio Mlaunch/Mfinish increases and, consequently, W increases as well. In this paper, the possibility of creating solid composite propellants (SCP) with zirconium (density 6.49 g/cm3) and zirconium hydride (density 5.61 g/cm3 ) as energetic compounds instead of aluminum is considered. It was found for what kinds of engines these propellants have to be more effective than propellants based on aluminum.

  11. The use of oxidized zirconium alloy in knee arthroplasty.

    PubMed

    Heyse, Thomas J; Haas, Steven B; Efe, Turgay

    2012-07-01

    Polyethylene wear is a key contributor to long-term failure in total knee arthroplasty. Oxidized zirconium alloy was created as a bearing surface for total joint arthroplasty in an attempt to address this concern. Oxidized zirconium has shown considerable improvements over existing materials in several key areas related to component longevity, including resistance to roughening, wear reduction, frictional behavior and biocompatibility. This review aims to summarize the current use of oxidized zirconium alloy in knee arthroplasty, as well as the possible advantages and downsides of this material. PMID:22905845

  12. RECOVERY OF URANIUM FROM ZIRCONIUM-URANIUM NUCLEAR FUELS

    DOEpatents

    Gens, T.A.

    1962-07-10

    An improvement was made in a process of recovering uranium from a uranium-zirconium composition which was hydrochlorinated with gsseous hydrogen chloride at a temperature of from 350 to 800 deg C resulting in volatilization of the zirconium, as zirconium tetrachloride, and the formation of a uranium containing nitric acid insoluble residue. The improvement consists of reacting the nitric acid insoluble hydrochlorination residue with gaseous carbon tetrachloride at a temperature in the range 550 to 600 deg C, and thereafter recovering the resulting uranium chloride vapors. (AEC)

  13. SEPARATION OF URANIUM FROM ZIRCONIUM AND NIOBIUM BY SOLVENT EXTRACTION

    DOEpatents

    Voiland, E.E.

    1958-05-01

    A process for separation of the uranium from zirconium and/or niobium values contained in 3 to 7M aqueous nitric acid solutions is described. This is accomplished by adding phosphoric acid anions to the nitric acid solution containing the uranium, zirconium, and/or niobium in an amount sufficient to make the solution 0.05 to 0.2M in phosphate ion and contacting the solution with an organic water-immiscible solvent such as MEK, whereby the uranyl values are taken up by the extract phase while the zirconium and niobium preferentially remain in the aqueous raffinate.

  14. METHOD OF PREPARING SINTERED ZIRCONIUM METAL FROM ITS HYDRIDES

    DOEpatents

    Angier, R.P.

    1958-02-11

    The invention relates to the preparation of metal shapes from zirconium hydride by powder metallurgical techniques. The zirconium hydride powder which is to be used for this purpose can be prepared by rendering massive pieces of crystal bar zirconium friable by heat treatment in purified hydrogen. This any then be ground into powder and powder can be handled in the air without danger of it igniting. It may then be compacted in the normal manner by being piaced in a die. The compact is sintered under vacuum conditions preferably at a temperature ranging from 1200 to 1300 deg C and for periods of one to three hours.

  15. Some History of Nitrates

    NASA Astrophysics Data System (ADS)

    Barnum, Dennis W.

    2003-12-01

    The history of saltpeter is an interesting combination of chemistry, world trade, technology, politics, and warfare. Originally it was obtained from the dirt floors of stables, sheep pens, pigeon houses, caverns, and even peasants' cottages; any place manure and refuse accumulated in soil under dry conditions. When these sources became inadequate to meet demand it was manufactured on saltpeter plantations, located in dry climates, where piles of dirt, limestone, and manure were allowed to stand for three to five years while soil microbes oxidized the nitrogen to nitrate—an example of early bioengineering. Extensive deposits of sodium nitrate were mined in the Atacama Desert in northern Chile from 1830 until the mid 1920s when the mines were displaced by the Haber Ostwald process.

  16. Nitrate reductase from Rhodopseudomonas sphaeroides.

    PubMed Central

    Kerber, N L; Cardenas, J

    1982-01-01

    The facultative phototroph Rhodopseudomonas sphaeroides DSM158 was incapable of either assimilating or dissimilating nitrate, although the organism could reduce it enzymatically to nitrite either anaerobically in the light or aerobically in the dark. Reduction of nitrate was mediated by a nitrate reductase bound to chromatophores that could be easily solubilized and functioned with chemically reduced viologens or photochemically reduced flavins as electron donors. The enzyme was solubilized, and some of its kinetic and molecular parameters were determined. It seemed to be nonadaptive, ammonia did not repress its synthesis, and its activity underwent a rapid decline when the cells entered the stationary growth phase. Studies with inhibitors and with metal antagonists indicated that molybdenum and possibly iron participate in the enzymatic reduction of nitrate. The conjectural significance of this nitrate reductase in phototrophic bacteria is discussed. PMID:6978883

  17. TREATMENT OF AMMONIUM NITRATE SOLUTIONS

    DOEpatents

    Boyer, T.W.; MacHutchin, J.G.; Yaffe, L.

    1958-06-10

    The treatment of waste solutions obtained in the processing of neutron- irradiated uranium containing fission products and ammonium nitrate is described. The object of this process is to provide a method whereby the ammonium nitrate is destroyed and removed from the solution so as to permit subsequent concentration of the solution.. In accordance with the process the residual nitrate solutions are treated with an excess of alkyl acid anhydride, such as acetic anhydride. Preferably, the residual nitrate solution is added to an excess of the acetic anhydride at such a rate that external heat is not required. The result of this operation is that the ammonium nitrate and acetic anhydride react to form N/sub 2/ O and acetic acid.

  18. Determination of fracture strength of δ-zirconium hydrides embedded in zirconium matrix at high temperatures

    NASA Astrophysics Data System (ADS)

    Kubo, T.; Kobayashi, Y.; Uchikoshi, H.

    2013-04-01

    The fracture strength of δ-zirconium hydrides embedded in a zirconium matrix was determined at temperatures between 25 °C and 250 °C by ring tensile tests using Zircaloy-2 tubes. Essentially all of the present hydrides in the tubes were re-oriented in the radial direction by a temperature cycling treatment and then tensile stress was applied perpendicular to the hydrides to ensure that brittle fracture would occur at the hydrides. The hydrides failed in a brittle manner below 100 °C where-as the zirconium matrix itself underwent ductile fracture without hydride cracking at temperatures above 200 °C under plane stress condition. Brittle fracture of the hydrides continued to occur at temperatures up to 250 °C under plane strain condition, suggesting that the upper limit temperature for hydride fracture, Tupper, was raised by the triaxial stress state under the plane strain condition. The apparent fracture strength of the hydrides, σhydridef, was determined at temperatures below Tupper from the measured fracture strength of the tubes, making a correction for the compressive transformation stress in the hydrides. σhydridef was about 710 MPa at temperatures between 25 °C and 250 °C at both plane stress and plane strain conditions. The temperature dependency was very small in this temperature range. Tupper was almost equivalent to the cross-over temperature between σhydridef and the ultimate tensile strength (UTS), which suggests that, at temperatures above Tupper, the zirconium matrix would undergo ductile fracture before the stress in the hydride is raised above σhydridef, since UTS is smaller than σhydridef.

  19. Delayed hydride cracking of zirconium alloys

    SciTech Connect

    Yau, T.L.; Webster, R.T.

    1995-10-01

    High-strength zirconium alloys are susceptible to a mechanism for crack initiation and propagation termed delayed hydride cracking (DHC). In these alloys, it is possible to generate a large enough stress gradient so that hydrogen moves to the highly stressed areas. Therefore, hydrides precipitate and grow in these areas. When the tensile stress is sufficiently great, crack initiation starts at some of these hydrides. Crack propagation occurs by repeating the same process at the crack tip. Of concern for the chemical process industries is the DHC of Zr-2.5Nb welds. Results of long-term tests and case histories indicate that stress relieving is one of the major measures for preventing DHC, provided that ASME mechanical requirements are met.

  20. Zirconium Hydride Space Power Reactor design.

    NASA Technical Reports Server (NTRS)

    Asquith, J. G.; Mason, D. G.; Stamp, S.

    1972-01-01

    The Zirconium Hydride Space Power Reactor being designed and fabricated at Atomics International is intended for a wide range of potential applications. Throughout the program a series of reactor designs have been evaluated to establish the unique requirements imposed by coupling with various power conversion systems and for specific applications. Current design and development emphasis is upon a 100 kilowatt thermal reactor for application in a 5 kwe thermoelectric space power generating system, which is scheduled to be fabricated and ground tested in the mid 70s. The reactor design considerations reviewed in this paper will be discussed in the context of this 100 kwt reactor and a 300 kwt reactor previously designed for larger power demand applications.

  1. Resonance ionization spectroscopy of zirconium atoms

    SciTech Connect

    Page, R.H.; Dropinski, S.C.; Worden, E.F. Jr.; Stockdale, J.A.D.

    1992-05-01

    We have examined the stepwise-resonant three-photon-ionization spectrum of neutral zirconium atoms using three separately-tunable pulsed visible dye lasers. Lifetimes of even-parity levels (measured with delayed-photoionization technique) range from 10 to 100 nsec. Direct ionization cross sections appear to be less than 10{sup {minus}17} cm{sup 2}; newly-detected autoionizing levels give peak ionization cross sections (inferred from saturation fluences) up to 10{sup {minus}15} cm{sup 2}. Members of Rydberg series converging to the 315 and 1323 cm{sup {minus}1} levels of Zr{sup +} were identified. ``Clumps`` of autoionizing levels are thought to be due to Rydberg-valence mixing.

  2. Zirconium deformation behavior: insights from EBSD measurements.

    SciTech Connect

    Bingert, J. F.; Mason, T. A.; Kaschner, G. C.; Maudlin, P. J.; Gray, G. T. , III

    2001-01-01

    The deformation of crystal-bar zirconium was investigated as a function of strain and strain rate through electron back-scattered diffraction (EBSD) characterization. The resultant data provided spatially resolved information on microstructure and texture evolution, individual twin system activity, and subsequent strain partitioning between twinned volume and parent grains. A range of deformation conditions was represented through quasi-static compression, 4-point beam bend tests at room and cryogenic temperature, and Taylor cylinder impact experiments. Effects from the interplay between slip and twinning deformation modes on anisotropic plasticity are considered in order to address the apparent trend toward isotropy at high rates. The role of various length scales on deformation behavior will be considered, along with the implications of these length scales on the assumptions typically invoked for plasticity modeling.

  3. PRECIPITATION OF ZIRCONIUM AND FLUORIDE IONS FROM SOLUTIONS

    DOEpatents

    Newby, B.J.

    1963-06-11

    A process is given for removing zirconium and fluorine ions from aqueous solutions also containing uranium(VI). The precipitation is carried out with sodium formate, and the uranium remains in solution. (AEC)

  4. Investigation of Electrochemical Recovery of Zirconium from Spent Nuclear Fuels

    SciTech Connect

    Michael Simpson; II-Soon Hwang

    2014-06-01

    This project uses both modeling and experimental studies to design optimal electrochemical technology methods for recovery of zirconium from used nuclear fuel rods for more effective waste management. The objectives are to provide a means of efficiently separating zirconium into metallic high-level waste forms and to support development of a process for decontamination of zircaloy hulls to enable their disposal as low- and intermediate-level waste. Modeling work includes extension of a 3D model previously developed by Seoul National University for uranium electrorefining by adding the ability to predict zirconium behavior. Experimental validation activities include tests for recovery of zirconium from molten salt solutions and aqueous tests using surrogate materials. *This is a summary of the FY 2013 progress for I-NERI project # 2010-001-K provided to the I-NERI office.

  5. Nucleation Pathways For Freezing Of Two Grades Of Zirconium

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Rulison, Aaron; Bayuzick, Robert; Hofmeister, William; Morton, Craig

    1996-01-01

    Report discusses classical nucleation theory of freezing and describes experimental study of nucleation mechanisms that predominate during freezing of spherical specimens of initially molten zirconium levitated electrostatically in vacuum.

  6. Process for massively hydriding zirconium--uranium fuel elements

    DOEpatents

    Katz, N.H.

    1973-12-01

    A method is described of hydriding uranium-zirconium alloy by heating the alloy in a vacuum, introducing hydrogen and maintaining an elevated temperature until occurrence of the beta--delta phase transformation and isobarically cooling the composition. (Official Gazette)

  7. Nitrate concentrations under irrigated agriculture

    USGS Publications Warehouse

    Zaporozec, A.

    1983-01-01

    In recent years, considerable interest has been expressed in the nitrate content of water supplies. The most notable toxic effect of nitrate is infant methemoglobinemia. The risk of this disease increases significantly at nitrate-nitrogen levels exceeding 10 mg/l. For this reason, this concentration has been established as a limit for drinking water in many countries. In natural waters, nitrate is a minor ionic constituent and seldom accounts for more than a few percent of the total anions. However, nitrate in a significant concentration may occur in the vicinity of some point sources such as septic tanks, manure pits, and waste-disposal sites. Non-point sources contributing to groundwater pollution are numerous and a majority of them are related to agricultural activities. The largest single anthropogenic input of nitrate into the groundwater is fertilizer. Even though it has not been proven that nitrogen fertilizers are responsible for much of nitrate pollution, they are generally recognized as the main threat to groundwater quality, especially when inefficiently applied to irrigated fields on sandy soils. The biggest challenge facing today's agriculture is to maintain the balance between the enhancement of crop productivity and the risk of groundwater pollution. ?? 1982 Springer-Verlag New York Inc.

  8. Quercetin as colorimetric reagent for determination of zirconium

    USGS Publications Warehouse

    Grimaldi, F.S.; White, C.E.

    1953-01-01

    Methods described in the literature for the determination of zirconium are generally designed for relatively large amounts of this element. A good procedure using colorimetric reagent for the determination of trace amounts is desirable. Quercetin has been found to yield a sensitive color reaction with zirconium suitable for the determination of from 0.1 to 50?? of zirconium dioxide. The procedure developed involves the separation of zirconium from interfering elements by precipitation with p-dimethylaminoazophenylarsonic acid prior to its estimation with quercetin. The quercetin reaction is carried out in 0.5N hydrochloric acid solution. Under the operating conditions it is indicated that quercetin forms a 2 to 1 complex with zirconium; however, a 2 to 1 and a 1 to 1 complex can coexist under special conditions. Approximate values for the equilibrium constants of the complexes are K1 = 0.33 ?? 10-5 and K2 = 1.3 ?? 10-9. Seven Bureau of Standards samples of glass sands and refractories were analyzed with excellent results. The method described should find considerable application in the analysis of minerals and other materials for macro as well as micro amounts of zirconium.

  9. Zirconium alkoxide interfaces for adhesion enhancement and electrocatalysis

    NASA Astrophysics Data System (ADS)

    Vanderkam, Susan Killian

    Tetra(tert-butoxy)zirconium was chemisorbed onto the native oxide layers of aluminum, iron, copper, and porous silicon, forming surface bound di- or tri-alkoxy zirconium species. Poly(ethylene- co-acrylic acid) was subsequently reacted with the surface forming chemically bound copolymer through carboxyzirconium linkages. Copolymer bound through the zirconium complex adhered to the metal oxide surfaces better than without the zirconium alkoxide intermediate, as determined by FTIR spectroscopy. Copper substrates were subjected to a variety of stability tests, including exposure to ambient conditions, base washing, and chronocoulometry. The copper-zirconium-copolymer ensemble was shown to be very stable in all of these tests. Indium tin oxide (ITO) powder was titrated to determine surface hydroxyl content per unit area. ITO-coated glass slides were reacted with tetra( tert-butoxy)zirconium, and subsequently with both carboxylic acid and phenol derivatives. Ferrocene-carboxyzirconium-coated ITO was characterized electrochemically, and the surface loading of ferrocene was found to be approximately one monolayer. Phenoxyzirconium-coated ITO was also characterized electrochemically and tested for electrocatalytic properties for the oxidation of several compounds in solution. Phenoxyzirconium-coated ITO was found to improve the oxidation kinetics for ferrocene and tetramethylphenylenediamine in acetonitrile.

  10. Zirconium behaviour during electrorefining of actinide-zirconium alloy in molten LiCl-KCl on aluminium cathodes

    NASA Astrophysics Data System (ADS)

    Meier, R.; Souček, P.; Malmbeck, R.; Krachler, M.; Rodrigues, A.; Claux, B.; Glatz, J.-P.; Fanghänel, Th.

    2016-04-01

    A pyrochemical electrorefining process for the recovery of actinides from metallic nuclear fuel based on actinide-zirconium alloys (An-Zr) in a molten salt is being investigated. In this process actinides are group-selectively recovered on solid aluminium cathodes as An-Al alloys using a LiCl-KCl eutectic melt at a temperature of 450 °C. In the present study the electrochemical behaviour of zirconium during electrorefining was investigated. The maximum amount of actinides that can be oxidised without anodic co-dissolution of zirconium was determined at a selected constant cathodic current density. The experiment consisted of three steps to assess the different stages of the electrorefining process, each of which employing a fresh aluminium cathode. The results indicate that almost a complete dissolution of the actinides without co-dissolution of zirconium is possible under the applied experimental conditions.

  11. Nitrate assimilation in Lotus japonicus.

    PubMed

    Márquez, Antonio J; Betti, Marco; García-Calderón, Margarita; Pal'ove-Balang, Peter; Díaz, Pedro; Monza, Jorge

    2005-07-01

    This paper summarizes some recent advances in the understanding of nitrate assimilation in the model legume Lotus japonicus. First, different types of experimental evidence are presented that emphasize the importance of the root in the nitrate-reducing assimilatory processes in this plant. Secondly, the main results from an ethyl methanesulphonate mutagenesis programme are presented. In this programme, chlorate-resistant and photorespiratory mutants were produced and characterized. The phenotype of one particular chlorate-resistant mutant suggested the importance of a low-affinity nitrate transport system for growth of L. japonicus plants under nitrate nutrition. The phenotype of photorespiratory mutants, affected in all forms of plastid glutamine synthetase in leaves, roots, and nodules, indicated that plastid glutamine synthetase was not required for primary nitrate assimilation nor for the symbiotic associations of the plant (nodulation, mycorrhization), provided photorespiration was suppressed. However, the phenotype of these mutants confirmed that plastid glutamine synthetase was required for the reassimilation of ammonium released by photorespiration. Finally, different aspects of the relationship between nitrate assimilation and osmotic stress in L. japonicus are also discussed, with specific reference to the biosynthesis of proline as an osmolyte. PMID:15911564

  12. Understanding the Irradiation Behavior of Zirconium Carbide

    SciTech Connect

    Motta, Arthur; Sridharan, Kumar; Morgan, Dane; Szlufarska, Izabela

    2013-10-11

    Zirconium carbide (ZrC) is being considered for utilization in high-temperature gas-cooled reactor fuels in deep-burn TRISO fuel. Zirconium carbide possesses a cubic B1-type crystal structure with a high melting point, exceptional hardness, and good thermal and electrical conductivities. The use of ZrC as part of the TRISO fuel requires a thorough understanding of its irradiation response. However, the radiation effects on ZrC are still poorly understood. The majority of the existing research is focused on the radiation damage phenomena at higher temperatures (>450{degree}C) where many fundamental aspects of defect production and kinetics cannot be easily distinguished. Little is known about basic defect formation, clustering, and evolution of ZrC under irradiation, although some atomistic simulation and phenomenological studies have been performed. Such detailed information is needed to construct a model describing the microstructural evolution in fast-neutron irradiated materials that will be of great technological importance for the development of ZrC-based fuel. The goal of the proposed project is to gain fundamental understanding of the radiation-induced defect formation in zirconium carbide and irradiation response by using a combination of state-of-the-art experimental methods and atomistic modeling. This project will combine (1) in situ ion irradiation at a specialized facility at a national laboratory, (2) controlled temperature proton irradiation on bulk samples, and (3) atomistic modeling to gain a fundamental understanding of defect formation in ZrC. The proposed project will cover the irradiation temperatures from cryogenic temperature to as high as 800{degree}C, and dose ranges from 0.1 to 100 dpa. The examination of this wide range of temperatures and doses allows us to obtain an experimental data set that can be effectively used to exercise and benchmark the computer calculations of defect properties. Combining the examination of radiation-induced microstructures mapped spatially and temporally, microstructural evolution during post-irradiation annealing, and atomistic modeling of defect formation and transport energetics will provide new, critical understanding about property changes in ZrC. The behavior of materials under irradiation is determined by the balance between damage production, defect clustering, and lattice response. In order to predict those effects at high temperatures so targeted testing can be expanded and extrapolated beyond the known database, it is necessary to determine the defect energetics and mobilities as these control damage accumulation and annealing. In particular, low-temperature irradiations are invaluable for determining the regions of defect mobility. Computer simulation techniques are particularly useful for identifying basic defect properties, especially if closely coupled with a well-constructed and complete experimental database. The close coupling of calculation and experiment in this project will provide mutual benchmarking and allow us to glean a deeper understanding of the irradiation response of ZrC, which can then be applied to the prediction of its behavior in reactor conditions.

  13. 46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... total combustible material; (3) Ammonium nitrate with ammonium sulfate containing more than 45 percent... 46 Shipping 5 2011-10-01 2011-10-01 false Ammonium nitrate and ammonium nitrate fertilizers. 148... Materials § 148.205 Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...

  14. 46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Ammonium nitrate and ammonium nitrate fertilizers. 148... Materials § 148.205 Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to the stowage and transportation in bulk of ammonium nitrate and the following fertilizers composed of...

  15. 46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Ammonium nitrate and ammonium nitrate fertilizers. 148... Materials § 148.205 Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to the stowage and transportation in bulk of ammonium nitrate and the following fertilizers composed of...

  16. 46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Ammonium nitrate and ammonium nitrate fertilizers. 148... Materials § 148.205 Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to the stowage and transportation in bulk of ammonium nitrate and the following fertilizers composed of...

  17. Equilibrium properties of hcp titanium and zirconium

    NASA Astrophysics Data System (ADS)

    Lu, Zhi-Wei; Singh, David; Krakauer, Henry

    1987-11-01

    The electronic and structural properties of hexagonal-close-packed titanium and zirconium are determined from self-consistent linearized augmented-plane-wave (LAPW) calculations within the framework of the local-density-functional approximation (LDA). The equilibrium lattice parameters, bulk moduli, Poisson's ratios, and cohesive energies are obtained from the total energies calculated as functions of the a and c lattice parameters. As found in other LDA calculations, the cohesive energies are overestimated compared to experiment, but otherwise generally good agreement with experiment is obtained. The uncertainty in the results due to the particular choice of the LDA exchange-correlation potential is also examined by performing parallel calculations using the Kohn-Sham-Gaspar Xα (α=(2/3) exchange-only potential. We find that these calculations yield equilibrium volumes which differ by 6-8 % (with the Xα results in better agreement with experiment) with proportional differences in other structural properties, which we take to be an indication of the intrinsic reliability of the LDA.

  18. Residual stresses in steel and zirconium weldments

    SciTech Connect

    Root, J.H.; Coleman, C.E.; Bowden, J.W.; Hayashi, Makoto

    1995-10-01

    Three dimensional scans of residual stress within intact weldments provide insight into the consequences of various welding techniques and stress-relieving procedures. The neutron diffraction method for non-destructive evaluation of residual stresses has been applied to a circumferential weld in a ferritic steel pipe of outer diameter 114 mm and thickness 8.6 mm. The maximum tensile stresses, 250 MPa in the hoop direction, are found at mid-thickness of the fusion zone. The residual stresses approach zero within 20 mm from the weld center. The residual stresses caused by welding zirconium alloy components are partially to blame for failures due to delayed-hydride cracking. Neutron diffraction measurements in a GTA-welded Zr-2.5Nb plate have shown that heat treatment at 530 C for 1 h reduces the longitudinal residual strain by 60%. Neutron diffraction has also been used to scan the residual stresses near circumferential electron beam welds in irradiated and unirradiated Zr-2.5Nb pressure tubes. The residual stresses due to electron beam welding appear to be lower than 130 MPa, even in the as-welded state. No significant changes occur in the residual stress pattern of the electron-beam welded tube, during a prolonged exposure to thermal neutrons and the temperatures typical of an operating nuclear reactor.

  19. Residual stresses in steel and zirconium weldments

    SciTech Connect

    Root, J.H.; Coleman, C.E.; Bowden, J.W.; Hayashi, M.

    1997-05-01

    Three-dimensional scans of residual stress within intact weldments provide insight into the consequences of various welding techniques and stress-relieving procedures. The neutron diffraction method for nondestructive evaluation of residual stresses has been applied to a circumferential weld in a ferritic steel pipe of outer diameter 114 mm and thickness 8.6 mm. The maximum tensile stresses, 250 MPa in the hoop direction, are found at mid-thickness of the fusion zone. The residual stresses approach zero within 20 mm from the weld center. The residual stresses caused by welding zirconium alloy components are partially to blame for failures due to delayed-hydride cracking. Neutron diffraction measurements in a GTA-welded Zr-2.5 Nb plate have shown that heat treatment at 530 C for 1 h reduces the longitudinal residual strain by 60%. Neutron diffraction has also been used to scan the residual stresses near circumferential electron beam welds in irradiated and unirradiated Zr-2.5 Nb pressure tubes. The residual stresses due to electron beam welding appear to be lower than 130 MPa, even in the as-welded state. No significant changes occur in the residual stress pattern of the electron-beam welded tube, during a prolonged exposure to thermal neutrons and the temperatures typical of an operating nuclear reactor.

  20. In situ ion irradiation of zirconium carbide

    NASA Astrophysics Data System (ADS)

    Ulmer, Christopher J.; Motta, Arthur T.; Kirk, Mark A.

    2015-11-01

    Zirconium carbide (ZrC) is a candidate material for use in one of the layers of TRISO coated fuel particles to be used in the Generation IV high-temperature, gas-cooled reactor, and thus it is necessary to study the effects of radiation damage on its structure. The microstructural evolution of ZrCx under irradiation was studied in situ using the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory. Samples of nominal stoichiometries ZrC0.8 and ZrC0.9 were irradiated in situ using 1 MeV Kr2+ ions at various irradiation temperatures (T = 20 K-1073 K). In situ experiments made it possible to continuously follow the evolution of the microstructure during irradiation using diffraction contrast imaging. Images and diffraction patterns were systematically recorded at selected dose points. After a threshold dose during irradiations conducted at room temperature and below, black-dot defects were observed which accumulated until saturation. Once created, the defect clusters did not move or get destroyed during irradiation so that at the final dose the low temperature microstructure consisted only of a saturation density of small defect clusters. No long-range migration of the visible defects or dynamic defect creation and elimination were observed during irradiation, but some coarsening of the microstructure with the formation of dislocation loops was observed at higher temperatures. The irradiated microstructure was found to be only weakly dependent on the stoichiometry.

  1. Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide

    PubMed Central

    Mizrahy, Ortal; Bar-Dolev, Maya; Guy, Shlomit; Braslavsky, Ido

    2013-01-01

    The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications. PMID:23555701

  2. Mechanical properties of zirconium alloys and zirconium hydrides predicted from density functional perturbation theory.

    PubMed

    Weck, Philippe F; Kim, Eunja; Tikare, Veena; Mitchell, John A

    2015-11-21

    The elastic properties and mechanical stability of zirconium alloys and zirconium hydrides have been investigated within the framework of density functional perturbation theory. Results show that the lowest-energy cubic Pn3[combining macron]m polymorph of δ-ZrH1.5 does not satisfy all the Born requirements for mechanical stability, unlike its nearly degenerate tetragonal P42/mcm polymorph. Elastic moduli predicted with the Voigt-Reuss-Hill approximations suggest that mechanical stability of α-Zr, Zr-alloy and Zr-hydride polycrystalline aggregates is limited by the shear modulus. According to both Pugh's and Poisson's ratios, α-Zr, Zr-alloy and Zr-hydride polycrystalline aggregates can be considered ductile. The Debye temperatures predicted for γ-ZrH, δ-ZrH1.5 and ε-ZrH2 are θD = 299.7, 415.6 and 356.9 K, respectively, while θD = 273.6, 284.2, 264.1 and 257.1 K for the α-Zr, Zry-4, ZIRLO and M5 matrices, i.e. suggesting that Zry-4 possesses the highest micro-hardness among Zr matrices. PMID:26478228

  3. Nitrate transport is independent of NADH and NAD(P)H nitrate reductases in barley seedlings

    NASA Technical Reports Server (NTRS)

    Warner, R. L.; Huffaker, R. C.

    1989-01-01

    Barley (Hordeum vulgare L.) has NADH-specific and NAD(P)H-bispecific nitrate reductase isozymes. Four isogenic lines with different nitrate reductase isozyme combinations were used to determine the role of NADH and NAD(P)H nitrate reductases on nitrate transport and assimilation in barley seedlings. Both nitrate reductase isozymes were induced by nitrate and were required for maximum nitrate assimilation in barley seedlings. Genotypes lacking the NADH isozyme (Az12) or the NAD(P)H isozyme (Az70) assimilated 65 or 85%, respectively, as much nitrate as the wild type. Nitrate assimilation by genotype (Az12;Az70) which is deficient in both nitrate reductases, was only 13% of the wild type indicating that the NADH and NAD(P)H nitrate reductase isozymes are responsible for most of the nitrate reduction in barley seedlings. For all genotypes, nitrate assimilation rates in the dark were about 55% of the rates in light. Hypotheses that nitrate reductase has direct or indirect roles in nitrate uptake were not supported by this study. Induction of nitrate transporters and the kinetics of net nitrate uptake were the same for all four genotypes indicating that neither nitrate reductase isozyme has a direct role in nitrate uptake in barley seedlings.

  4. Experimental study on flames propagating through zirconium particle clouds.

    PubMed

    Yin, Yi; Sun, Jinhua; Ding, Yibin; Guo, Song; He, Xuechao

    2009-10-15

    To reveal the mechanisms of flame propagation through the hardly volatile metal dust clouds clearly, the flame propagating through zirconium particle clouds has been examined experimentally. A high-speed video camera was used to record the propagation process of the flame. Combustion zone temperature was detected by a fine thermocouple. Based on the experimental results, structure of flame and combustion courses of zirconium particles were analyzed, the combustion propagation in zirconium dust was investigated, and the velocity and temperature characteristics of the combustion zone were also elucidated. The combustion zone propagating through zirconium particle clouds consists of luminous particles. Particle concentration plays an important role in the combustion zone propagation process. With the increase of zirconium particle concentration, the maximum temperature of the combustion zone increases at the lower concentration, takes a maximum value, and then decreases at the higher concentration. It is also found that the propagation velocity of the combustion zone has a linear relationship with its maximum temperature. PMID:19477589

  5. Irradiation simulation of zirconium using high energy argon implantation

    NASA Astrophysics Data System (ADS)

    Peng, D. Q.; Bai, X. D.; Pan, F.

    2007-03-01

    In order to simulate the irradiation damage, the argon ion was implanted in the zirconium with fluence ranging from 1×10 16 to 1×10 17 ions/cm 2, using accelerating implanter at an extraction voltage of 190 kV at liquid nitrogen temperature. Then the effect of argon ion implantation on the aqueous corrosion behavior of zirconium was studied. The valence states of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy (XPS). Glancing angle X-ray diffraction (GAXRD) was employed to examine the phase transformation due to the argon ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zirconium in a 1 M H 2SO 4 solution. From XPS, there existed adsorbed carbon and a little of oxygen (depth less than 20 nm) in the surface of samples, zirconium changed from zirconia to metallic zirconium along the depth direction. From GAXRD, the argon-implanted samples are little oxidized. It was found that the corrosion resistance of implanted samples declined with increasing the fluence, which is attributed to the removing of oxide protection layer and the irradiation damage.

  6. Reduction of nitrate in Shewanella

    SciTech Connect

    Gao, Haichun; Yang, Zamin Koo; Barua, Sumitra; Reed, SB; Nealson, Kenneth H.; Fredrikson, JK; Tiedje, James; Zhou, Jizhong

    2009-01-01

    In the genome of Shewanella oneidensis, a napDAGHB gene cluster encoding periplasmic nitrate reductase (NapA) and accessory proteins and an nrfA gene encoding periplasmic nitrite reductase (NrfA) have been identified. These two systems seem to be atypical because the genome lacks genes encoding cytoplasmic membrane electron transport proteins, NapC for NAP and NrfBCD/NrfH for NRF, respectively. Here, we present evidence that reduction of nitrate to ammonium in S. oneidensis is carried out by these atypical systems in a two-step manner. Transcriptional and mutational analyses suggest that CymA, a cytoplasmic membrane electron transport protein, is likely to be the functional replacement of both NapC and NrfH in S. oneidensis. Surprisingly, a strain devoid of napB encoding the small subunit of nitrate reductase exhibited the maximum cell density sooner than the wild type. Further characterization of this strain showed that nitrite was not detected as a free intermediate in its culture and NapB provides a fitness gain for S. oneidensis to compete for nitrate in the environments. On the basis results from mutational analyses of napA, napB, nrfA and napBnrfA in-frame deletion mutants, we propose that NapB is able to favor nitrate reduction by routing electrons to NapA exclusively.

  7. Synthesis and characterization of a mesoporous hydrous zirconium oxide used for arsenic removal from drinking water

    SciTech Connect

    Bortun, Anatoly; Bortun, Mila; Pardini, James; Khainakov, Sergei A.; Garcia, Jose R.

    2010-02-15

    Powder (20-50 {mu}m) mesoporous hydrous zirconium oxide was prepared from a zirconium salt granular precursor. The effect of some process parameters on product morphology, porous structure and adsorption performance has been studied. The use of hydrous zirconium oxide for selective arsenic removal from drinking water is discussed.

  8. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges...

  9. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges...

  10. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges...

  11. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges...

  12. 40 CFR 421.330 - Applicability: Description of the primary zirconium and hafnium subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... primary zirconium and hafnium subcategory. 421.330 Section 421.330 Protection of Environment ENVIRONMENTAL... CATEGORY Primary Zirconium and Hafnium Subcategory § 421.330 Applicability: Description of the primary zirconium and hafnium subcategory. The provisions of this subpart are applicable to discharges...

  13. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  14. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  15. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  16. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Modified salicylic acid, zirconium... Specific Chemical Substances 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  17. Synthesis of micro-dispersed zirconium oxide for glass manufacturing

    NASA Astrophysics Data System (ADS)

    Goncharuk, V.; Starodubtsev, P.; Maslennikova, I.

    2016-01-01

    A rather simple and original method for processing of zirconium-containing raw material form Algoma deposit (Khabarovsk region, Russia) was suggested, which comprised fluorination of the initial sample with a diluted HF solution followed by the thermal treatment of fluorination products and pyrohydrolysis of zirconium tetrafluoride. Water vapors obtained by hydrogen and oxygen burning in a hydrogen torch as well as by simple evaporation were used for pyrohydrolysis. The feed rate of the water and its temperature were regulated. The temperature of water vapors reached 800-1200 °C. Zirconium dioxide with a purity of 99.97% or more and a dispersity of 0.1 gm or less was synthesized.

  18. METHOD OF FABRICATING A URANIUM-ZIRCONIUM HYDRIDE REACTOR CORE

    DOEpatents

    Weeks, I.F.; Goeddel, W.V.

    1960-03-22

    A method is described of evenly dispersing uranlum metal in a zirconium hydride moderator to produce a fuel element for nuclear reactors. According to the invention enriched uranium hydride and zirconium hydride powders of 200 mesh particle size are thoroughly admixed to form a mixture containing 0.1 to 3% by weight of U/sup 235/ hydride. The mixed powders are placed in a die and pressed at 100 tons per square inch at room temperature. The resultant compacts are heated in a vacuum to 300 deg C, whereby the uranium hydride deoomposes into uranium metal and hydrogen gas. The escaping hydrogen gas forms a porous matrix of zirconium hydride, with uramum metal evenly dispersed therethrough. The advantage of the invention is that the porosity and uranium distribution of the final fuel element can be more closely determined and controlled than was possible using prior methods of producing such fuel ele- ments.

  19. Studies on synthesis esterified zirconium glyphosates and their hydrophobic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yaqing; Li, Minglei; Ji, Xuemei; Xu, Qinghong

    2010-03-01

    A series of new organic-modified zirconium glyphosate compounds were synthesized based on the reactions between esterified glyphosates and ZrOCl 2. FT-IR spectra, solid-state 31P MAS NMR and elementary analysis proved the formation of these new compounds. Powder X-ray diffraction (PXRD) patterns and transmission electron microscope (TEM) images proved these compounds had lamellar structures. Scanning electronic microscope (SEM) images showed that solvents used in synthesis had great influence on the morphologies of products. Water contact angle measurements showed that the hydrophobic property of the products was a function of the number of carbon in esterified glyphosates, increased from 0° of zirconium glyphosate to 133° of dodecyl zirconium glyphosate. The present study offered a new route to synthesize organic-modified α-Zr(HPO 4) 2·H 2O (α-ZrP) materials with various morphology and controllable hydrophobic property.

  20. Process for electrolytic deposition of metals on zirconium materials

    DOEpatents

    Donaghy, Robert E.

    1979-01-30

    A process for the electrolytic deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electrolytic plating solution containing the metal to be deposited on the article in the presence of an electrode receiving current.

  1. Process for electroless deposition of metals on zirconium materials

    DOEpatents

    Donaghy, Robert E.

    1978-01-01

    A process for the electroless deposition of a metal layer on an article comprised of zirconium or a zirconium alloy is disclosed. The article is activated in an aged aqueous solution comprising from about 10 to about 20 grams per liter ammonium bifluoride and from about 0.75 to about 2 grams per liter of sulfuric acid. The solution is aged by immersion of pickled zirconium in the solution for at least about 10 minutes. The loosely adhering film formed on the article in the activating step is removed and the article is contacted with an electroless plating solution containing the metal to be deposited on the article upon sufficient contact with the article.

  2. Nitrate Trends in Minnesota Rivers

    USGS Publications Warehouse

    Wall, Dave; Christopherson, Dave; Lorenz, Dave; Martin, Gary

    2013-01-01

    The objective of this study was to assess long-term trends (30 to 35 years) of flow-adjusted concentrations of nitrite+nitrate-N (hereinafter referred to as nitrate) in a way that would allow us to discern changing trends. Recognizing that these trends are commonly different from one river to another river and from one part of the state to another, our objective was to examine as many river monitoring sites across the state as possible for which sufficient long term streamflow and concentration data were available.

  3. Thermophysical properties of reaction processed zirconium diboride

    NASA Astrophysics Data System (ADS)

    Lonergan, Jason Michael

    This dissertation focuses on the thermophysical properties of high purity zirconium diboride ceramics. These ceramics have shown promise for potential applications such as leading edge materials for next generation hypersonic vehicles. The overall goal of this work was to improve the understanding of the thermal properties and maximize the thermal conductivity of ZrB2 . Four main areas were investigated in this work. First, the sintering kinetics and the intrinsic thermal properties of reaction processed ZrB 2 were studied and compared to ZrB2 produced by hot pressing commercial powders. The reaction process produced ceramics with higher thermal conductivity and enhanced densification. Next, Hf impurity concentrations were varied showing that decreasing Hf content increased thermal conductivity. Finally, isotope enrichments were performed showing that lighter isotopes increased lattice frequency and subsequently thermal conductivity. Fully enriched Zr10B2 had a thermal conductivity of 145 W/m*K which is the highest value for ZrB2 reported to date. Scattering models based on quantum mechanics were used with density functional theory to analyze the effects of impurities and isotopes on the electron and phonon density of states. Overall, this work adds insight into the fundamental mechanisms behind the thermophysical properties of ZrB2. Tailoring compositions to reduce Hf content and adjusting boron isotope concentration has led to improved thermal properties at all temperatures. The processing conditions, reported properties, and insights gained from models will help the realization of ZrB2 as a leading edge material for the next generation of hypersonic vehicles.

  4. Hydrogen pickup mechanism of zirconium alloys

    NASA Astrophysics Data System (ADS)

    Couet, Adrien

    Although the optimization of zirconium based alloys has led to significant improvements in hydrogen pickup and corrosion resistance, the mechanisms by which such alloy improvements occur are still not well understood. In an effort to understand such mechanisms, a systematic study of the alloy effect on hydrogen pickup is conducted, using advanced characterization techniques to rationalize precise measurements of hydrogen pickup. The hydrogen pick-up fraction is accurately measured for a specially designed set of commercial and model alloys to investigate the effects of alloying elements, microstructure and corrosion kinetics on hydrogen uptake. Two different techniques to measure hydrogen concentrations were used: a destructive technique, Vacuum Hot Extraction, and a non-destructive one, Cold Neutron Prompt Gamma Activation Analysis. The results indicate that hydrogen pickup varies not only from alloy to alloy but also during the corrosion process for a given alloy. For instance Zircaloy type alloys show high hydrogen pickup fraction and sub-parabolic oxidation kinetics whereas ZrNb alloys show lower hydrogen pickup fraction and close to parabolic oxidation kinetics. Hypothesis is made that hydrogen pickup result from the need to balance charge during the corrosion reaction, such that the pickup of hydrogen is directly related to (and indivisible of) the corrosion mechanism and decreases when the rate of electron transport or oxide electronic conductivity sigmao xe through the protective oxide increases. According to this hypothesis, alloying elements (either in solid solution or in precipitates) embedded in the oxide as well as space charge variations in the oxide would impact the hydrogen pick-up fraction by modifying sigmaox e, which drives oxidation and hydriding kinetics. Dedicated experiments and modelling were performed to assess and validate these hypotheses. In-situ electrochemical impedance spectroscopy (EIS) experiments were performed on Zircaloy-4 tubes to directly measure the evolution of sigma oxe as function of exposure time. The results show that sigmao xe decreases as function of exposure time and that its variations are directly correlated to the instantaneous hydrogen pickup fraction variations. The electron transport through the oxide layer is thus altered as the oxide grows, reasons for which are yet to be exactly determined. Preliminary results also show that sigma oxe of ZrNb alloys would be much higher compared with Zircaloy-4. Thus, it is confirmed that sigmaox e is a key parameter in the hydrogen and oxidation mechanism. Because the mechanism whereby alloying elements are incorporated into the oxide layer is critical to changing sigmao xe, the evolution of the oxidation state of two common alloying elements, Fe and Nb, when incorporated into the growing oxide layers is investigated using X-Ray Absorption Near-Edge Spectroscopy (XANES) using micro-beam synchrotron radiation on cross sectional oxide samples. The results show that the oxidation of both Fe and Nb is delayed in the oxide layer compared to that of Zr, and that this oxidation delay is related to the variations of the instantaneous hydrogen pick-up fraction with exposure time. The evolution of Nb oxidation as function of oxide depth is also compatible with space charge compensation in the oxide and with an increase in sigmaox e of ZrNb alloys compared to Zircaloys. Finally, various successively complex models from the well-known Wagner oxidation theory to the more complex effect of space charge on oxidation kinetics have been developed. The general purpose of the modeling effort is to provide a rationale for the sub-parabolic oxidation kinetics and demonstrate the correlation with hydrogen pickup fraction. It is directly demonstrated that parabolic oxidation kinetics is associated with high sigmao xe and low space charges in the oxide whereas sub-parabolic oxidation kinetics is associated with lower sigmaox e and higher space charge in the oxide. All these observations helped us to propose a general corrosion mechanism of zirconium alloys involving both oxidation and hydrogen pickup mechanism to better understand and predict the effect of alloying additions on the behavior of zirconium alloys.

  5. In-situ stabilization of radioactive zirconium swarf

    DOEpatents

    Hess, Clay C.

    1999-01-01

    The method for treating ignitable cutting swarf in accordance with the present invention involves collecting cutting swarf in a casting mold underwater and injecting a binder mixture comprising vinyl ester styrene into the vessel to fill void volume; and form a mixture comprising swarf and vinyl ester styrene; and curing the mixture. The method is especially useful for stabilizing the ignitable characteristics of radioactive zirconium cutting swarf, and can be used to solidify zirconium swarf, or other ignitable finely divided material, underwater. The process could also be performed out of water with other particulate wastes.

  6. Stress corrosion cracking of zirconium in nitric acid

    SciTech Connect

    Beavers, J A; Griess, J C; Boyd, W K

    1980-01-01

    The susceptibility of zirconium and its common alloys to stress corrosion cracking (SCC) in nitric acid was investigated by slow strain-rate and constant deflection techniques. Cracking occurred at 25/sup 0/C over a wide range of acid concentrations and electrochemical potentials. The crack velocity increased slightly with increasing temperature. The failure mode was transgranular and the morphology was similar to SCC failures of zirconium alloys in other environments. The fracture was very orientation-dependent suggesting that it occurs on a single crystallographic plane in the material. The results of the study are not consistent with a hydrogen mechanism for cracking.

  7. Surface and corrosion study of laser-processed zirconium alloys

    SciTech Connect

    Rawers, J.; Bullard, S. ); Reitz, W. ); Roub, E.K. . Dept. of Mechanical Engineering)

    1991-10-01

    This paper discusses Reactor Grade Zirconium (Zircaloy 2) laser-glazed and laser alloyed with nickel (Ni) or chromium (Cr) powders. Laser alloying produced a surface that was macroscopically, chemically homogeneous. However, at the microscopic level the melt zone was a mixture of microcrystalline pure zirconium (Zr) and extremely fine, or possibly amorphous, solid solution regions of Zr and alloying elements. Corrosion tests (potentiodynamic and long-term immersion) were conducted in 10% FeCl{sub 3} solution. The potentiodynamic tests showed i{sub corr} and E{sub corr} were a strong function of surface conditioning, altered by gritblasting, laser processing, acid cleaning, and heat treating.

  8. In-situ stabilization of radioactive zirconium swarf

    DOEpatents

    Hess, C.C.

    1999-08-31

    The method for treating ignitable cutting swarf in accordance with the present invention involves collecting cutting swarf in a casting mold underwater and injecting a binder mixture comprising vinyl ester styrene into the vessel to fill void volume; and form a mixture comprising swarf and vinyl ester styrene; and curing the mixture. The method is especially useful for stabilizing the ignitable characteristics of radioactive zirconium cutting swarf, and can be used to solidify zirconium swarf, or other ignitable finely divided material, underwater. The process could also be performed out of water with other particulate wastes. 6 figs.

  9. A new conducting nanocomposite -- PPy-zirconium (IV) oxide

    SciTech Connect

    Bhattacharya, A.; De, A.; Sarkar, S.; Ganguly, K.M.

    1996-05-01

    Pyrrole was polymerized in the presence of ultrafine zirconium (IV) oxide (ZrO{sub 2}) particles which act as a dispersant for pyrrole. Room temperature conductivities of the resulting polypyrrole-zirconium (IV) oxide nanocomposites having different ZrO{sub 2} particle concentrations were measured and were compared with that of bare polypyrrole. It was observed that the conductivities of the nanocomposites were higher than that of the polypyrrole without ZrO{sub 2} and increased with ZrO{sub 2} concentration up to a certain limit. From transmission electron microscope studies, particle size and morphology of the nanocomposites and ZrO{sub 2} particles were obtained.

  10. Zirconium diboride nanofiber generation via microwave arc heating.

    PubMed

    Baldridge, Tyson; Gupta, Mool C

    2008-07-01

    Ultrahigh temperature zirconium diboride nanofibers were produced by microwave arc heating using micron-sized raw powder. While microwave heating the ZrB(2) powder, the development of local arcing led to rapid heating and solidification of the samples, along with the creation of nanofibers. The morphology of these high aspect ratio nanofibers was characterized using scanning electron microscopy and transmission electron microscopy. Energy dispersive x-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction showed the composition to contain zirconium, boron, nitrogen, aluminum and oxygen as well as the crystallographic orientation. ZrB(2) nanofiber applications include aerospace and other harsh environments. PMID:21828708

  11. Zirconium diboride nanofiber generation via microwave arc heating

    NASA Astrophysics Data System (ADS)

    Baldridge, Tyson; Gupta, Mool C.

    2008-07-01

    Ultrahigh temperature zirconium diboride nanofibers were produced by microwave arc heating using micron-sized raw powder. While microwave heating the ZrB2 powder, the development of local arcing led to rapid heating and solidification of the samples, along with the creation of nanofibers. The morphology of these high aspect ratio nanofibers was characterized using scanning electron microscopy and transmission electron microscopy. Energy dispersive x-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction showed the composition to contain zirconium, boron, nitrogen, aluminum and oxygen as well as the crystallographic orientation. ZrB2 nanofiber applications include aerospace and other harsh environments.

  12. In-situ stabilization of radioactive zirconium swarf

    SciTech Connect

    Hess, Clay C.

    1997-12-01

    The method for treating ignitable cutting swarf in accordance with the present invention involves collecting cutting swarf in a casting mold underwater and injecting a binder mixture comprising vinyl ester styrene into the vessel to fill void volume; and form a mixture comprising swarf and vinyl ester styrene; and curing the mixture. The method is especially useful for stabilizing the ignitable characteristics of radioactive zirconium cutting swarf, and can be used to solidify zirconium swarf, or other ignitable finely divided material, underwater. The process could also be performed out of water with other particulate wastes.

  13. Experiments on explosive interactions between zirconium-containing melt and water (ZREX).

    SciTech Connect

    Cho, D. H.

    1998-04-10

    The results of two series of experiments on explosive interactions between zirconium-containing melt and water are described. The first series of experiments involved dropping 1-kg batches of zirconium-zirconium dioxide mixture melt into a column of water while the second series employed 1.2-kg batches of zirconium-stainless steel mixture melt. Explosions took place only in those tests which were externally triggered. While the extent of zirconium oxidation in the triggered experiments was quite large, the explosion energies estimated from the experimental measurements were found to be small compared to the combined thermal and chemical energy available.

  14. Chemistry of zirconium related to the behavior of nuclear fuel cladding. Final report

    SciTech Connect

    Cubicciotti, D.

    1980-03-26

    Studies of the chemistry of the zirconium-iodine and zirconium-oxygen systems were undertaken to elucidate their thermodynamics and kinetics. It is anticipated that the results obtained will lead to an improved understanding of the chemical processes involved in chemically assisted fuel rod failures. This project not only has classified the thermodynamics of both the gas phase and the solids in the zirconium-iodine system, it has also provided valuable information on the chemisorption of iodine and of oxygen on zirconium surfaces at high temperatures. In addition, the kinetics of reactions on zirconium surfaces were studied. These results have already been helpful in understanding the stress corrosion cracking of Zircaloy.

  15. Zirconium nanoparticles prepared by the reduction of zirconium oxide using the RAPET method

    PubMed Central

    Eshed, Michal; Pol, Swati; Balasubramanian, Mahalingam

    2011-01-01

    Summary The aim of the current work is the synthesis and characterization of metallic Zr nanoparticles. The preparation is carried out by using the RAPET method (Reaction under Autogenic Pressure at Elevated Temperatures) developed in our lab. The RAPET reaction of commercial ZrO2 with Mg powder was carried out in a closed stainless steel cell, at 750 °C. On completion of the reaction, the additionally formed MgO is removed by treatment with acid. The characterization of the product was performed by XRD, X-ray absorption spectroscopy, SEM, TEM and elemental analysis. The XRD pattern reveals that the product is composed of pure metallic zirconium, without any traces of the MgO by-product. PMID:21977431

  16. Biological denitrification of high concentration nitrate waste

    DOEpatents

    Francis, Chester W.; Brinkley, Frank S.

    1977-01-01

    Biological denitrification of nitrate solutions at concentrations of greater than one kilogram nitrate per cubic meter is accomplished anaerobically in an upflow column having as a packing material a support for denitrifying bacteria.

  17. Sensing of NO2 with Zirconium Hydroxide via Electrical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Harris, Coleman; Soliz, Jennifer; Klevitch, Andrew; Rossin, Joseph; Fountain, Augustus, III; Peterson, Gregory; Hauser, Adam

    Nitrogen Dioxide (NO2) is a brown gas mainly produced as a byproduct of burning fossil fuels, such as automobiles and power plants. Nitrogen oxides can form acid rain and smog by reacting with air, can form toxic organic nitrates by reacting with soil, and can react with oxygen in water, destroying marine life due to a lack of breathable oxygen. Any concentration beyond 53 ppb (air quality standard) can cause irritation to the lungs and respiratory infections, and higher dosages can be fatal. As such, research in NO2 detection is incredibly important to human welfare. Zirconium hydroxide (Zr(OH)4) has been investigated as a candidate NO2 dielectric sensor using impedance spectroscopy analysis. Impedance changes of several orders of magnitude are seen down to our dosage minimum of 50 ppmhr. Changes in impedance correlate with nitrogen and oxygen atomic ratio increases observed via X-ray photoelectron spectroscopy (XPS). The results indicate that Zr(OH)4 may be a strong candidate for use in impedance-based NO2 detection devices. A.J.H., J.R.S., A.W.F. and G.W. P. acknowledge funding under Army Research Office STIR Award #W911F-15-1-0104. J.R.S. acknowledges funding under a NRC fellowship and is advised by Dr. Christopher Karwacki, ECBC.

  18. Influence of zirconium on microstructure and toughness of low-alloy steel weld metals

    NASA Astrophysics Data System (ADS)

    Trindade, V. B.; Mello, R. S. T.; Payão, J. C.; Paranhos, R. P. R.

    2006-06-01

    The influence of zirconium on microstructure and toughness of low-alloy steel weld metal was studied. Weld metals with different zirconium contents were obtained adding iron-zirconium alloy in the welding flux formulation. Weld metal chemical composition proved that zirconium was able to be transferred from the flux to the weld metal. The addition of zirconium refined the weld metal microstructure, increasing the acicular ferrite content. Weld metal toughness, determined by means of impact Charpy-V tests, showed that the zirconium addition is beneficial up to a content of 0.005 wt.%. Above this level, zirconium was not able to produce further microstructure refinement, although the toughness was reduced, possibly due to the formation of microconstituent such as the martensite-austenite constituent (M-A), which is considered to be deleterious to the weld metal toughness.

  19. Characterization of uranium and uranium-zirconium deposits produced in electrorefining of spent nuclear fuel

    SciTech Connect

    Totemeier, T.C.

    1997-09-01

    This paper describes the metallurgical characterization of deposits produced in molten salt electrorefining of uranium and uranium - 10.% zirconium alloy. The techniques of characterization are described with emphasis on considerations given to the radioactive and pyrophoric nature of the samples. The morphologies observed and their implications for deposit performance are also presented - samples from pure uranium deposits were comprised of chains of uranium crystals with a characteristic rhomboidal shape, while morphologies of samples from deposits containing zirconium showed more polycrystalline features. Zirconium was found to be present as a second, zirconium metal phase at or very near the uranium-zirconium dendrite surfaces. Higher collection efficiencies and total deposit weights were observed for the uranium-zirconium deposits; this performance increase is likely a result of better mechanical properties exhibited by the uranium-zirconium dendrite morphology. 18 refs., 10 figs., 1 tab.

  20. A Novel Chemical Nitrate Destruction Process

    SciTech Connect

    Dziewinski, J.; Marczak, S.

    1999-03-01

    Nitrates represent one of the most significant pollutant discharged to the Baltic Sea by the Sliiamae hydrometallurgical plant. This article contains a brief overview of the existing nitrate destruction technologies followed by the description of a new process developed by the authors. The new chemical process for nitrate destruction is cost effective and simple to operate. It converts the nitrate to nitrogen gas which goes to the atmosphere.

  1. Plasma nitrate and nitrite are increased by a high nitrate supplement, but not by high nitrate foods in older adults

    PubMed Central

    Miller, Gary D.; Marsh, Anthony P.; Dove, Robin W.; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S. Bruce; Kim-Shapiro, Daniel

    2012-01-01

    Little is known about the effect of dietary nitrate on the nitrate/nitrite/NO (nitric oxide) cycle in older adults. We examined the effect of a 3-day control diet vs. high nitrate diet, with and without a high nitrate supplement (beetroot juice), on plasma nitrate and nitrite kinetics, and blood pressure using a randomized four period cross-over controlled design. We hypothesized that the high nitrate diet would show higher levels of plasma nitrate/nitrite and blood pressure compared to the control diet, which would be potentiated by the supplement. Participants were eight normotensive older men and women (5 female, 3 male, 72.5±4.7 yrs) with no overt disease or medications that affect NO metabolism. Plasma nitrate and nitrite levels and blood pressure were measured prior to and hourly for 3 hours after each meal. The mean daily changes in plasma nitrate and nitrite were significantly different from baseline for both control diet+supplement (p<0.001 and =0.017 for nitrate and nitrite, respectively) and high nitrate diet+supplement (p=0.001 and 0.002), but not for control diet (p=0.713 and 0.741) or high nitrate diet (p=0.852 and 0.500). Blood pressure decreased from the morning baseline measure to the three 2 hr post-meal follow-up time-points for all treatments, but there was no main effect for treatment. In healthy older adults, a high nitrate supplement consumed at breakfast elevated plasma nitrate and nitrite levels throughout the day. This observation may have practical utility for the timing of intake of a nitrate supplement with physical activity for older adults with vascular dysfunction. PMID:22464802

  2. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed...

  3. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed...

  4. 21 CFR 172.170 - Sodium nitrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate. 172.170 Section 172.170 Food and... Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified... follows: (1) As a preservative and color fixative, with or without sodium nitrite, in smoked,...

  5. 21 CFR 172.170 - Sodium nitrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and... Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified... follows: (1) As a preservative and color fixative, with or without sodium nitrite, in smoked,...

  6. Nitration of Naphthol: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Mowery, Dwight F.

    1982-01-01

    Products of nitrations, upon distillation or steam distillation, may produce dermatitis in some students. A procedure for nitration of beta-naphthol producing a relatively non-volatile product not purified by steam distillation is described. Nitration of alpha-naphthol by the same procedure yields Martius Yellow dye which dyes wool yellow or

  7. Modeling nitrate removal in a denitrification bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Denitrification beds are being promoted to reduce nitrate concentrations in agricultural drainage water to alleviate the adverse environmental effects associated with nitrate pollution in surface water. In this system, water flows through a trench filled with a carbon media where nitrate is transfor...

  8. 21 CFR 172.160 - Potassium nitrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium nitrate. 172.160 Section 172.160 Food... ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely used as a curing agent in the processing of...

  9. 21 CFR 172.160 - Potassium nitrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Food Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely...

  10. 21 CFR 172.160 - Potassium nitrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Food Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely...

  11. Post-translational Regulation of Nitrate Reductase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrate reductase (NR) catalyzes the reduction of nitrate to nitrite, which is the first step in the nitrate assimilation pathway, but can also reduce nitrite to nitric oxide (NO), an important signaling molecule that is thought to mediate a wide array of of developmental and physiological processes...

  12. 21 CFR 172.160 - Potassium nitrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely used as a...

  13. 21 CFR 172.160 - Potassium nitrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Food Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely...

  14. 21 CFR 172.170 - Sodium nitrate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and... Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified... follows: (1) As a preservative and color fixative, with or without sodium nitrite, in smoked,...

  15. 21 CFR 172.170 - Sodium nitrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and... PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Food Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified foods in accordance with...

  16. 21 CFR 172.170 - Sodium nitrate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and... Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified... follows: (1) As a preservative and color fixative, with or without sodium nitrite, in smoked,...

  17. Method of producing thin cellulose nitrate film

    DOEpatents

    Lupica, S.B.

    1975-12-23

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent.

  18. Nitration of Naphthol: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Mowery, Dwight F.

    1982-01-01

    Products of nitrations, upon distillation or steam distillation, may produce dermatitis in some students. A procedure for nitration of beta-naphthol producing a relatively non-volatile product not purified by steam distillation is described. Nitration of alpha-naphthol by the same procedure yields Martius Yellow dye which dyes wool yellow or…

  19. Efflux Of Nitrate From Hydroponically Grown Wheat

    NASA Technical Reports Server (NTRS)

    Huffaker, R. C.; Aslam, M.; Ward, M. R.

    1992-01-01

    Report describes experiments to measure influx, and efflux of nitrate from hydroponically grown wheat seedlings. Ratio between efflux and influx greater in darkness than in light; increased with concentration of nitrate in nutrient solution. On basis of experiments, authors suggest nutrient solution optimized at lowest possible concentration of nitrate.

  20. The corrosion of zirconium under deep geologic repository conditions

    NASA Astrophysics Data System (ADS)

    Shoesmith, David W.; Zagidulin, Dmitrij

    2011-11-01

    Zirconium alloys are widely used in nuclear reactors as fuel cladding and as reactor structural elements (i.e., CANDU reactor pressure tubes), and are therefore a component of the waste materials that could be emplaced in a deep geologic repository. Therefore, the corrosion mechanisms and rates for relevant zirconium alloys under repository conditions have been reviewed. Since titanium and zirconium alloys have many similarities, and because the data base for the corrosion of titanium alloys under repository conditions is considerably more extensive than that for zirconium alloys, the electrochemical and corrosion behavior of both materials have been compared and evaluated. Although electrochemical studies suggest Zircaloy cladding could be susceptible to pitting, redox conditions within a failed waste container will remain reducing and unable to support pitting. This leaves passive corrosion as the only long-term corrosion mechanism. The available data indicates that the rate of passive corrosion will be very low. A rate of 20 nm/year would be a reasonable upper limit but it is likely the rate will be less than 1 nm/year.

  1. Scaling-down antibody radiolabeling reactions with zirconium-89.

    PubMed

    Knight, James C; Paisey, Stephen J; Dabkowski, Adam M; Marculescu, Cristina; Williams, Anwen S; Marshall, Christopher; Cornelissen, Bart

    2016-04-12

    The most widely cited procedures for radiolabeling antibodies with zirconium-89 for immuno-PET require multi-milligram amounts of antibody which can be cost-prohibitive, particularly during the research and development process. We therefore sought to develop a reliable (89)Zr-radiolabeling procedure that provides high radiochemical yields at the microgram scale. PMID:26986633

  2. Nanophase Nickel-Zirconium Alloys for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

    2008-01-01

    Nanophase nickel-zirconium alloys have been investigated for use as electrically conductive coatings and catalyst supports in fuel cells. Heretofore, noble metals have been used because they resist corrosion in the harsh, acidic fuel cell interior environments. However, the high cost of noble metals has prompted a search for less-costly substitutes. Nickel-zirconium alloys belong to a class of base metal alloys formed from transition elements of widely different d-electron configurations. These alloys generally exhibit unique physical, chemical, and metallurgical properties that can include corrosion resistance. Inasmuch as corrosion is accelerated by free-energy differences between bulk material and grain boundaries, it was conjectured that amorphous (glassy) and nanophase forms of these alloys could offer the desired corrosion resistance. For experiments to test the conjecture, thin alloy films containing various proportions of nickel and zirconium were deposited by magnetron and radiofrequency co-sputtering of nickel and zirconium. The results of x-ray diffraction studies of the deposited films suggested that the films had a nanophase and nearly amorphous character.

  3. Cr-Cu-Zr (Chromium-Copper-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Chromium-Copper-Zirconium.

  4. Cu-Si-Zr (Copper-Silicon-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Copper-Silicon-Zirconium.

  5. Cu-Mg-Zr (Copper-Magnesium-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Copper-Magnesium-Zirconium.

  6. Cu-Ni-Zr (Copper-Nickel-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Copper-Nickel-Zirconium.

  7. Cu-Ti-Zr (Copper-Titanium-Zirconium)

    NASA Astrophysics Data System (ADS)

    Materials Science International Team MSIT

    This document is part of Subvolume C3 'Non-Ferrous Metal Systems. Part 3: Selected Soldering and Brazing Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Copper-Titanium-Zirconium.

  8. Mineral resource of the month: zirconium and hafnium

    USGS Publications Warehouse

    Gambogi, Joseph

    2007-01-01

    Zirconium and hafnium are corrosion-resistant metals that are grouped in the same family as titanium on the periodic table. The two elements commonly occur in oxide and silicate minerals and have significant economic importance in everything from ink, ceramics and golf shoes to nuclear fuel rods.

  9. Surface modification of layered zirconium phosphate with PNIPAM.

    PubMed

    Wang, Xuezhen; Zhao, Di; Medina, Ilse B Nava; Diaz, Agustin; Wang, Huiliang; Clearfield, Abraham; Mannan, M Sam; Cheng, Zhengdong

    2016-04-01

    A new method was reported to modify layered zirconium phosphate (ZrP) with thermoresponsive polymer PNIPAM (poly N-isopropylacrylamide). PNIPAM was proved to be covalently grafted onto ZrP. (60)Co γ-rays irradiation produced peroxide groups on the surface which, upon heating, initiated free radical polymerization and subsequent attachment of PNIPAM. PMID:26966882

  10. Surface characterization of anodized zirconium for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sanchez, A. Gomez; Schreiner, W.; Duffó, G.; Ceré, S.

    2011-05-01

    Mechanical properties and corrosion resistance of zirconium make this material suitable for biomedical implants. Its good in vivo performance is mainly due to the presence of a protective oxide layer that minimizes corrosion rate, diminishes the amount of metallic ions released to the biological media and facilitates the osseointegration process. Since the implant surface is the region in contact with living tissues, the characteristics of the surface film are of great interest. Surface modification is a route to enhance both biocompatibility and corrosion resistance of permanent implant materials. Anodizing is presented as an interesting process to modify metal surfaces with good reproducibility and independence of the geometry. In this work the surface of zirconium before and after anodizing in 1 mol/L phosphoric acid solution at a fixed potential between 3 and 30 V, was characterized by means of several surface techniques. It was found that during anodization the surface oxide grows with an inhomogeneous coverage on zirconium surface, modifying the topography. The incorporation of P from the electrolyte to the surface oxide during the anodizing process changes the surface chemistry. After 30 days of immersion in Simulated Body Fluid (SBF) solution, Ca-P rich compounds were present on anodized zirconium.

  11. Phosphorus Recovery Using Zirconium-Loaded Saponified Orange Juice Residue

    NASA Astrophysics Data System (ADS)

    Harada, Hiroyuki; Kondo, Mitsunori; Biswas, Biplob K.; Ohura, Seichirou; Inoue, Katsutoshi; Ishikawa, Susumu; Kawakita, Hidetaka; Ohto, Keisuke

    Zirconium was immobilized to orange juice residue, to investigate the feasibility of using zirconium-loaded saponified orange juice residue (Zr-SOJR) for phosphorus recovery from secondary effluent and the extraction solution from incinerated sewage sludge ash by using H2SO4 and HCl. These had phosphorus concentrations of 68.2 mg/dm3 and 5.9 mg/dm3, respectively. The phosphorus removal rate secondary effluent increased with an increasing solid/liquid ratio in batch experiments. The adsorption capacity of Zr-SOJR was also compared with those obtained using a synthetic phosphorus solution and using zirconium-loaded ferrite. The prepared absorbent was effective for phosphorus removal and exhibited a reasonably high sorption capacity, twice that of zirconium ferrite. Secondary effluent was treated by packed column, and this reached break-through after 300 bed volumes. The results from phosphorous extraction from the ash indicate that can be treated with acid to efficiently recover phosphorous and thus can be absorbed by Zr-SOJR.

  12. Manufacturing process to reduce large grain growth in zirconium alloys

    DOEpatents

    Rosecrans, Peter M.

    1987-01-01

    A method of treating cold-worked zirconium alloys to reduce large grain gth during thermal treatment at temperatures above the recrystallization temperature of the alloy comprising heating the cold-worked alloy between about 1300.degree.-1350.degree. F. for 1 to 3 hours prior to treatment above its recrystallization temperature.

  13. Extraction of rare earth metal(III) nitrates with trialkylmethylammonium nitrate from multicomponent solutions containing ammonium nitrate

    SciTech Connect

    Pyartman, A.K.; Puzikov, E.A.; Bogatov, K.B.

    1994-10-20

    A study has been made of the extraction of rare earth elements (III) (praseodymium-lutetium, yttrium) by trialkylmethylammonium nitrate in kerosine (1.10 M) from binary and multicomponent solutions containing 1.0-3.0 M of ammonium nitrate. Physicochemical and mathematical models have been proposed for the distribution of individual lanthanides (III) depending on the composition of the initial raw material and on the total REE(III) and ammonium nitrate concentrations in the aqueous phase. The optimal concentration ranges for total REE and ammonium nitrate in the aqueous phase have been found for separating complex REE concentrates by using trialkylmethylammonium nitrate in the diluent.

  14. Nitrated fatty acids: Synthesis and measurement

    PubMed Central

    Woodcock, Steven R.; Bonacci, Gustavo; Gelhaus, Stacy L.; Schopfer, Francisco J.

    2012-01-01

    Nitrated fatty acids are the product of nitrogen dioxide reaction with unsaturated fatty acids. The discovery of peroxynitrite and peroxidase-induced nitration of biomolecules led to the initial reports of endogenous nitrated fatty acids. These species increase during ischemia reperfusion, but concentrations are often at or near the limits of detection. Here, we describe multiple methods for nitrated fatty acid synthesis, sample extraction from complex biological matrices, and a rigorous method of qualitative and quantitative detection of nitrated fatty acids by LC-MS. In addition, optimized instrument conditions and caveats regarding data interpretation are discussed. PMID:23200809

  15. Continuous flow nitration in miniaturized devices

    PubMed Central

    2014-01-01

    Summary This review highlights the state of the art in the field of continuous flow nitration with miniaturized devices. Although nitration has been one of the oldest and most important unit reactions, the advent of miniaturized devices has paved the way for new opportunities to reconsider the conventional approach for exothermic and selectivity sensitive nitration reactions. Four different approaches to flow nitration with microreactors are presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed. PMID:24605161

  16. Phytochrome, Nitrate Movement, and Induction of Nitrate Reductase in Etiolated Pea Terminal Buds 1

    PubMed Central

    Jones, Richard W.; Sheard, Robert W.

    1975-01-01

    The role of phytochrome in the induction of nitrate reductase of etiolated field peas (Pisum arvense L.) was examined. Terminal bud nitrate concentration increased in darkness, and the increase correlated with induction of nitrate reductase following brief exposure of intact plants to red, blue, far red, and white lights. Brief light exposure of intact plants stimulated nitrate uptake and induction of nitrate reductase by terminal buds subsequently excised and incubated on nitrate solution in darkness; exposure of excised buds in contact with nitrate led to less uptake but more induction. Nitrate and nitrate reductase activity both declined during incubation with water, irrespective of light treatment. Nitrate enrichment of intact terminal buds and uptake into excised buds and increases in nitrate reductase activity were all red/far red reversible. Dimethyl sulfoxide (1%, v/v) and sugars (sucrose 0.5%, glucose 1, w/v), although stimulating nitrate uptake into excised tissue in darkness, failed to enhance nitrate reductase activity over dark controls. Phytochrome may regulate nitrate reductase via both nitrate movement and a general mechanism such as enhancement of protein synthesis. PMID:16659226

  17. Deconstructing nitrate isotope dynamics in aquifers

    NASA Astrophysics Data System (ADS)

    Granger, J.

    2012-12-01

    The natural abundance N and O stable isotope ratios of nitrate provide an invaluable tool to differentiate N sources to the environment, track their dispersal, and monitor their attenuation by biological transformations. The interpretation of patterns in isotope abundances relies on knowledge of the isotope ratios of the source end-members, as well as on constraints on the isotope discrimination imposed on nitrate by respective biological processes. Emergent observations from mono-culture experiments of denitrifying bacteria reveal nitrate fractionation trends that appear at odds with trends ascribed to denitrification in soils and aquifers. This discrepancy raises the possibility that additional biological N transformations may be acting in tandem with denitrification. Here, the N and O isotope enrichments associated with nitrate removal by denitrification in aquifers are posited to bear evidence of coincident biological nitrate production - from nitrification and/or from anammox. Simulations are presented from a simple time-dependent one-box model of a groundwater mass ageing that is subject to net nitrate loss by denitrification with coincident nitrate production by nitrification or anammox. Within boundary conditions characteristic of freshwater aquifers, the apparent slope of the parallel enrichments in nitrate N and O isotopes associated with net N loss to denitrification can vary in proportion to the nitrate added simultaneous by oxidative processes. Pertinent observations from nitrate plumes in suboxic to anoxic aquifers are examined to validate this premise. In this perspective, nitrate isotope distributions suggest that we may be missing important N fluxes inherent to most aquifers.

  18. Nitrate Utilization by the Diatom Skeletonema costatum

    PubMed Central

    Serra, Juan L.; Llama, Maria J.; Cadenas, Eduardo

    1978-01-01

    Nitrate uptake has been studied in nitrogen-deficient cells of the marine diatom Skeletonema costatum. When these cells are incubated in the presence of nitrate, this ion is quickly taken up from the medium, and nitrite is excreted by the cells. Nitrite is excreted following classical saturation kinetics, its rate being independent of nitrate concentration in the incubation medium for nitrate concentration values higher than 3 micromolar. Nitrate uptake shows mixed-transfer kinetics, which can be attributed to the simultaneous contributions of mediated and diffusion transfer. Cycloheximide and p-hydroxymercuribenzoate inhibit the carrier-mediated contribution to nitrate uptake, without affecting the diffusion component. When cells are preincubated with nitrate, the net nitrogen uptake is increased. PMID:16660652

  19. High performance ammonium nitrate propellant

    NASA Technical Reports Server (NTRS)

    Anderson, F. A. (Inventor)

    1979-01-01

    A high performance propellant having greatly reduced hydrogen chloride emission is presented. It is comprised of: (1) a minor amount of hydrocarbon binder (10-15%), (2) at least 85% solids including ammonium nitrate as the primary oxidizer (about 40% to 70%), (3) a significant amount (5-25%) powdered metal fuel, such as aluminum, (4) a small amount (5-25%) of ammonium perchlorate as a supplementary oxidizer, and (5) optionally a small amount (0-20%) of a nitramine.

  20. Syntheses and structural characterization of zirconium-tin and zirconium-lead binary and ternary systems

    SciTech Connect

    Kwon, Y.U.

    1991-01-28

    The binary zirconium-tin system was reinvestigated. The A15 phase appears to be a line phase with a Zr{sub 4}Sn composition. The Zr{sub 5}Sn{sub 3} (Mn{sub 5}Si{sub 3}-type) and Zr{sub 5}Sn{sub 4} (Ti{sub 5}Ga{sub 4}-type) compounds are line phases below 1000{degree}C, the latter being a self-interstitial phase of the former. ZrSn{sub 2} is the tin-richest phase. There is an one-phase region between these phases with partial self-interstitials at high temperatures. The zirconium-lead system behaves similarly: there are an A15 phase with a Zr{sub {approximately}5.8}Pb composition, Zr{sub 5}Pb{sub 3} (Mn{sub 5}Si{sub 3}-type) and Zr{sub 5}Pb{sub 4} (Ti{sub 5}Ga{sub 4-type}) compounds, and a high temperature solid solution between Zr{sub 5}Pb{sub >3.5} and Zr{sub 5}Pb{sub 4} from below 1000{degree}C; however, the ZrSn{sub 2} analogue is not formed. The Mn{sub 5}Si{sub 3}-type phases in these systems can accommodate third elements interstitially to form stoichiometric compounds Zr{sub 5}Sn{sub 3}Z (Z = B, C, N, O, Al, Si, P, S, Cu, Zn, Ga, Ge, and As and Se) and Zr{sub 5}Pb{sub 3}Z (Z = Al, Si, P, S, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Ag, Cd, In, Sn, Sb and Te) as well as their self-interstitial derivatives. The systems Zr-Sn-T, T = Fe, Co and Ni, did not produce stoichiometric interstitial phases Zr{sub 5}Sn{sub 3}T. Instead, the interstitial phases for these elements are formed only with excess tin that partially occupies the interstitial site together with a T element. Reducing the amount of tin in these systems yields two new phases; Zr{sub 5}Sn{sub 2+x}Fe{sub 1-x} (0 {le} {times} {le} 0.28) (W{sub 5}Si{sub 3}-type) and Zr{sub 6}Sn{sub 2}Fe (Zr{sub 6}Al{sub 2}Co-type) as characterized by X-ray single crystal analyses. A cobalt analogue for the latter was also synthesized.

  1. Layered zirconium phosphonate with inorganic–organic hybrid structure: Preparation and its assembly with DNA

    SciTech Connect

    Liu, Li-Min; Lu, Guo-Yuan; Jiang, Li-Ping; Zhu, Jun-Jie

    2014-07-01

    An aminoethoxy-functionalized zirconium phosphonate (Zr(O{sub 3}POCH{sub 2}CH{sub 2}NH{sub 2}){sub 2}·3H{sub 2}O), abbreviated as ZrRP (R=OCH{sub 2}CH{sub 2}NH{sub 2}), with layered structure has been synthesized. This layered compound possesses the characteristic of inorganic–organic hybrid, due to the covalently linked aminoethoxy in the host layer. The anion exchanged property of this zirconium phosphonate is suitable for the direct intercalation of negatively charged DNA, which is different from these reported zirconium phosphates or zirconium phosphonates. As a precursor, this prepared zirconium phosphonate was utilized to fabricate a novel DNA/ZrRP binary hybrid via a delamination-reassembly procedure. The release behavior of DNA from the DNA/ZrRP composite was investigated at different medium pH, because the combination between zirconium phosphonate sheets and DNA was pH-dependent sensitively. Moreover, the helical conformation of DNA was almost retained after the intercalation and release process. These properties of the DNA/ZrRP composite suggested the potential application of layered zirconium phosphonate as a non-viral vector in gene delivery. - Graphical abstract: The intercalation of DNA into zirconium phosphonate and the release of DNA from the interlayer of zirconium phosphonate. - Highlights: ●A layered aminoethoxy-functionalized zirconium phosphonate has been synthesized. ●DNA was intercalated directly into the prepared zirconium phosphonate. ●A novel zirconium phosphonate/DNA binary hybrid was fabricated. ●DNA can be reversibly released from the interlayer of zirconium phosphonate. ●The intercalation/release processes do not induce the denaturalization of DNA.

  2. Catalyzed reduction of nitrate in aqueous solutions

    SciTech Connect

    Haas, P.A.

    1994-08-01

    Sodium nitrate and other nitrate salts in wastes is a major source of difficulty for permanent disposal. Reduction of nitrate using aluminum metal has been demonstrated, but NH{sub 3}, hydrazine, or organic compounds containing oxygen would be advantageous for reduction of nitrate in sodium nitrate solutions. Objective of this seed money study was to determine minimum conditions for reduction. Proposed procedure was batchwise heating of aqueous solutions in closed vessels with monitoring of temperatures and pressures. A simple, convenient apparatus and procedure were demonstrated for observing formation of gaseous products and collecting samples for analyses. The test conditions were 250{degree}C and 1000 psi max. Any useful reduction of sodium nitrate to sodium hydroxide as the primary product was not found. The nitrate present at pHs < 4 as HNO{sub 3} or NH{sub 4}NO{sub 3} is easily decomposed, and the effect of nitromethane at these low pHs was confirmed. When acetic acid or formic acid was added, 21 to 56% of the nitrate in sodium nitrate solutions was reduced by methanol or formaldehyde. With hydrazine and acetic acid, 73 % of the nitrate was decomposed to convert NaNO{sub 3} to sodium acetate. With hydrazine and formic acid, 36% of the nitrate was decomposed. If these products are more acceptable for final disposal than sodium nitrate, the reagents are cheap and the conversion conditions would be practical for easy use. Ammonium acetate or formate salts did not significantly reduce nitrate in sodium nitrate solutions.

  3. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  4. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  5. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  6. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  7. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  8. Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: implications for present and future nitrate optical depth

    NASA Astrophysics Data System (ADS)

    Paulot, F.; Ginoux, P.; Cooke, W. F.; Donner, L. J.; Fan, S.; Lin, M.; Mao, J.; Naik, V.; Horowitz, L. W.

    2015-09-01

    We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model (AM3). Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 %, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 %) or in the uptake of nitric acid on dust (13 %). Our best estimate for present-day fine nitrate optical depth at 550 nm is 0.006 (0.005-0.008). We only find a modest increase of nitrate optical depth (< 30 %) in response to the projected changes in the emissions of SO2 (-40 %) and ammonia (+38 %) from 2010 to 2050. Nitrate burden is projected to increase in the tropics and in the free troposphere, but to decrease at the surface in the midlatitudes because of lower nitric acid concentrations. Our results suggest that better constraints on the heterogeneous chemistry of nitric acid on dust, on tropical ammonia emissions, and on the transport of ammonia to the free troposphere are needed to improve projections of aerosol optical depth.

  9. Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: implications for present and future nitrate optical depth

    NASA Astrophysics Data System (ADS)

    Paulot, F.; Ginoux, P.; Cooke, W. F.; Donner, L. J.; Fan, S.; Lin, M.-Y.; Mao, J.; Naik, V.; Horowitz, L. W.

    2016-02-01

    We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model (AM3). Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 %, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 %) or in the uptake of nitric acid on dust (13 %). Our best estimate for fine nitrate optical depth at 550 nm in 2010 is 0.006 (0.005-0.008). In wintertime, nitrate aerosols are simulated to account for over 30 % of the aerosol optical depth over western Europe and North America. Simulated nitrate optical depth increases by less than 30 % (0.0061-0.010) in response to projected changes in anthropogenic emissions from 2010 to 2050 (e.g., -40 % for SO2 and +38 % for ammonia). This increase is primarily driven by greater concentrations of nitrate in the free troposphere, while surface nitrate concentrations decrease in the midlatitudes following lower concentrations of nitric acid. With the projected increase of ammonia emissions, we show that better constraints on the vertical distribution of ammonia (e.g., convective transport and biomass burning injection) and on the sources and sinks of nitric acid (e.g., heterogeneous reaction on dust) are needed to improve estimates of future nitrate optical depth.

  10. Effect of nitrate on microbial perchlorate reduction

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Coates, J. D.

    2007-12-01

    Over the last decade perchlorate has been recognized as an important emerging water contaminant that poses a significant public health threat. Because of its chemical stability, low ionic charge density, and significant water solubility microbial remediation has been identified as the most feasible method for its in situ attenuation. Our previous studies have demonstrated that dissimilatory perchlorate reducing bacteria (DPRB) capable of the respiratory reduction of perchlorate into innocuous chloride are ubiquitous in soil and sedimentary environments. As part of their metabolism these organisms reduce perchlorate to chlorite which is subsequently dismutated into chloride and molecular oxygen. These initial steps are mediated by the perchlorate reductase and chlorite dismutase enzymes respectively. Previously we found that the activity of these organisms is dependent on the presence of molybdenum and is inhibited by the presence of oxygen and to different extents nitrate. However, to date, there is little understanding of the mechanisms involved in the regulation of perchlorate reduction by oxygen and nitrate. As a continuation of our studies into the factors that control DPRB activity we investigated these regulatory mechanisms in more detail as a model organism, Dechloromonas aromatica strain RCB, transitions from aerobic metabolism through nitrate reduction to perchlorate reduction. In series of growth transition studies where both nitrate and perchlorate were present, preference for nitrate to perchlorate was observed regardless of the nitrate to perchlorate ratio. Even when the organism was pre-grown anaerobically in perchlorate, nitrate was reduced prior to perchlorate. Using non-growth washed cell suspension, perchlorate- grown D. aromatica was capable of reducing both perchlorate and nitrate concomitantly suggesting the preferentially utilization of nitrate was not a result of enzyme functionality. To elucidate the mechanism for preferential utilization of nitrate, transcripts of perchlorate reductase and chlorite dismutase were analyzed to determine possible transcriptional regulation from nitrate. During growth transition studies, increase in the level of transcripts necessary for nitrate reduction and perchlorate reduction was observed concomitantly with decrease in the concentration of nitrate and perchlorate respectively suggesting transcriptional regulation was involved in the preferential utilization of nitrate and that nitrate might be a transcriptional inhibitor of perchlorate reduction. Again, using non-growth washed cell suspensions of perchlorate grown D. aromatica, a decrease of transcript level of the perchlorate reductase but not the chlorite dismutase was observed after incubation with nitrate. In conclusion, from physiological and molecular evidence, nitrate negatively regulates transcription of perchlorate reductase thus inhibiting perchlorate reduction. This result is unexpected as it is in contrast to the accepted dogma that microorganisms regulate their metabolisms to utilize electron acceptors in a sequential manner based on thermodynamic optimization which would imply that perchlorate should be used preferentially to nitrate.

  11. Nitrate deposition and impact on Adirondack streams

    SciTech Connect

    Simonin, H.A.; Kretser, W.A.

    1997-12-31

    Acidic deposition has a great impact on water chemistry and fish populations in the Adirondack region. Although the Clean Air Act Amendments of 1990 have resulted in some reductions of sulfate deposition, nitrate deposition has not yet been well controlled, and continues to impact aquatic resources. As part of the USEPA funded Episodic Response Project four Adirondack headwater streams were intensively monitored over an 18 month period. Atmospheric deposition was also monitored at a centrally located station. The quantity of nitrate being deposited on the study watersheds was calculated based on monthly net deposition data which ranged from 0.6 kg/ha/month to 3.6 kg/ha/month. These data were then compared to the monthly export of nitrate from the watershed in these streams. Nitrate concentrations were highest in the streamwater during the spring snowmelt period prior to the time when forest vegetation actively utilizes nitrate. On an annual basis the amount of nitrate which left the watershed via stream water exceeded the amount which fell as nitrate deposition. These data are important in documenting the impact of nitrate in the acidification of Adirondack streams during the spring, which coincides with brook trout hatching. Control programs for nitrous oxide emissions are presently aimed at reducing ozone levels during the May-September period. These emissions control programs need to be expanded to also reduce nitrate deposition in the sensitive Adirondack region during the winter and spring periods when nitrate deposition has its greatest impact on aquatic resources.

  12. Nitrate deposition and impact of Adirondack streams

    SciTech Connect

    Simonin, H.A.; Kretser, W.

    1995-12-31

    Acidic deposition has a great impact on water chemistry and fish populations in the Adirondack region. Although the Clean Air Act Amendments of 1990 have resulted in some reductions of sulfur deposition, nitrate deposition has not yet been well controlled, and continues to impact aquatic resources. As part of the USEPA funded Episodic Response Project, four Adirondack headwater streams were intensively monitored over an 18 month period. Atmospheric deposition was also monitored at a centrally located station. The quantity of nitrate being deposited on the study watersheds was calculated based on monthly net deposition data, which ranged from 0.6 kg/ha/month to 3.6 kg/ha/month. These data were then compared to the monthly export of nitrate from the watershed in these streams. Nitrate concentrations were highest in the stream water during the spring snowmelt period prior to the time when forest vegetation actively utilizes nitrate. On an annual basis, the amount of nitrate that left the watershed via stream water was approximately equal to the amount that fell as nitrate deposition. These data are important in documenting the impact that nitrate has in acidifying Adirondack streams during the spring, which coincides with brook trout hatching. Control programs for nitrous oxide emissions are presently aimed at reducing ozone levels during the May--September period. These emissions control programs need to be expanded to also reduce nitrate deposition in the sensitive Adirondack region during the water and spring periods when nitrate deposition has its greatest impact on aquatic resources.

  13. Nuclear-grade zirconium prepared by combining combustion synthesis with molten-salt electrorefining technique

    NASA Astrophysics Data System (ADS)

    Li, Hui; Nersisyan, Hayk H.; Park, Kyung-Tae; Park, Sung-Bin; Kim, Jeong-Guk; Lee, Jeong-Min; Lee, Jong-Hyeon

    2011-06-01

    Zirconium has a low absorption cross-section for neutrons, which makes it an ideal material for use in nuclear reactor applications. However, hafnium typically contained in zirconium causes it to be far less useful for nuclear reactor materials because of its high neutron-absorbing properties. In the present study, a novel effective method has been developed for the production of hafnium-free zirconium. The process includes two main stages: magnesio-thermic reduction of ZrSiO 4 under a combustion mode, to produce zirconium silicide (ZrSi), and recovery of hafnium-free zirconium by molten-salt electrorefining. It was found that, depending on the electrorefining procedure, it is possible to produce zirconium powder with a low hafnium content: 70 ppm, determined by ICP-AES analysis.

  14. Experiments on interactions between zirconium-containing melt and water (ZREX): Hydrogen generation and chemical augmentation of energetics

    SciTech Connect

    Cho, D.H.; Armstrong, D.R.; Gunther, W.H.; Basu, S.

    1997-08-01

    The results of the first data series of experiments on interactions between zirconium-containing melt and water are described. These experiments involved dropping 1-kg batches of pure zirconium or zirconium-zirconium dioxide mixture melt into a column of water. A total of nine tests were conducted, including four with pure zirconium melt and five with Zr-ZrO{sub 2} mixture melt. Explosions took place only in those tests which were externally triggered. While the extent of zirconium oxidation in the triggered experiments was quite extensive, the estimated explosion energetics were found to be very small compared to the combined thermal and chemical energy available.

  15. Adhesion Improvement of Zirconium Coating on Polyurethane Modified by Plasmas

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Hao, Xiaofei; Liu, Jiwei

    2016-02-01

    In order to improve the adhesion of the middle frequency magnetic sputtered zirconium coating on a polyurethane film, an anode layer source was used to pretreat the polyurethane film with nitrogen and oxygen ions. SEMs and AFM roughness profiles of treated samples and the contrast groups were obtained. Besides, XPS survey spectrums and high resolution spectrums were also investigated. The adhesion test revealed that ion bombardment could improve the adhesion to the polyurethane coating substrate. A better etching result of oxygen ions versus nitrogen predicts a higher bonding strength of zirconium coating on polyurethane and, indeed, the highest bonding strengths are for oxygen ion bombardment upto 13.3 MPa. As demonstrated in X-ray photoelectron spectroscopy, the oxygen ion also helps to introduce more active groups, and, therefore, it achieves a high value of adhesion strength.

  16. Stress corrosion cracking of zirconium used in the reprocessing plant

    SciTech Connect

    Kato, Chiaki; Motooka, Takafumi; Yamamoto, Masahiro

    2007-07-01

    We investigated stress corrosion cracking (SCC) of zirconium by constant load test and the small-scale mock-up test simulated the fuel dissolve. These tests operated in the simulated solution, which substituted non-radioactive elements, i.e. V with radioactive elements such as Pu and Np. From the results of constant load test, the cracks were not observed on 150 MPa after 908 hours in approximately 3 % strain. However a lot of cracks caused by SCC were observed over 20 % strain under high tensile stress in the simulated solution and the heat-transfer condition having more corrosive circumstance and noble potential accelerated the susceptibility of SCC. The cracking behavior would be caused by the creep phenomena. The small-scale mock-up test had been operated for about 50000 hours during 7 year. From the results, zirconium showed excellent corrosion resistance and no SCC was observed during these long-term operations. (authors)

  17. Effects of solutes on damage production and recovery in zirconium

    SciTech Connect

    Zee, R.H.; Birtcher, R.C.; MacEwen, S.R.; Abromeit, C.

    1986-04-01

    Dilute zirconium-based alloys and pure zirconium were irradiated at 10 K with spallation neutrons at IPNS. Four types of alloys - Zr-Ti, Zr-Sn, Zr-Dy and Zr-Au - each with three concentration levels, were used. Low-temperature resistivity damage rates are enhanced by the presence of any of the four solutes. The greatest enhancement was produced by Au while the least by Dy. Within each alloy group, damage production also increased but at a decreasing rate, with increasing concentration. Post-irradiation annealing experiments, up to 400 K, showed that all four solutes suppress recovery due to interstitial migration, indicative of interstitial trapping by the solutes. Vacancy recovery is also suppressed by the presence of Sn, Dy or Au. The effect of Ti is to shift this stage to lower temperature. No clear correlation between the results with solute size was detected.

  18. A review on hydride precipitation in zirconium alloys

    NASA Astrophysics Data System (ADS)

    Bair, Jacob; Asle Zaeem, Mohsen; Tonks, Michael

    2015-11-01

    Nucleation and formation of hydride precipitates in zirconium alloys have been an important factor in limiting the lifetime of nuclear fuel cladding for over 50 years. This review provides a concise summary of experimental and computational studies performed on hydride precipitation in zirconium alloys since the 1960's. Different computational models, including density functional theory, molecular dynamics, phase field, and finite element models applied to study hydride precipitation are reviewed, with specific consideration given to the phase field model, which has become a popular and powerful computational tool for modeling microstructure evolution. The strengths and weaknesses of these models are discussed in detail. An outline of potential future work in this area is discussed as well.

  19. Alternative Processing of High Temperature Hafnium and Zirconium Based Materials

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew; Gusman, Michael; Ellerby, Don; Irby, Edward; Johnson, Sylvia M.

    2003-01-01

    The behavior of refractory hafnium and zirconium based materials are being investigated at NASA Ames as part of ongoing research aimed at developing superior heat resistant materials for aerospace applications. Hafnium and zirconium diboride based materials have shown high temperature capabilities in simulated reentry environments indicating that these materials may successfully operate as reusable oxidation resistant components for leading edge applications. Due to the refractory nature of these materials, processing of fine-grained uniform microstructures poses a number of challenges. To better understand the process-property-microstructure relationship, processing of these materials has been carried out with conventional hot pressing in addition to the novel approach of Spark Plasma Sintering (SPS). The two processing methods are compared and contrasted in an evaluation of the sintering behavior of high temperature diboride based materials and preliminary physical and mechanical properties are presented.

  20. Complex formation in the system zirconium-diantipyrylpropylmethane-acidic dye

    SciTech Connect

    Shtokalo, M.I.; Kostenko, E.E.

    1985-05-01

    Previously, the authors used a metal indicator method to examine the formation of complexes of zirconium with diantipyrylpropylmethane (DAPM) and have shown that two complexes, Zr (DAPM)/sup 4 +/ and Zr (DAPM) /sup 4 +//sub 2/ are formed in 0.1 and 1.0 M HC1, with stability constants of 5.10.10/sup 10/ and 3.80.10/sup 14/ respectively. Now the authors combine this complex with the acidic dye 2-(4-sulfonphenylazo)-1.8-dihydroxynaphthalene-3.6-disulfonic acid (SPADNS). The optimal conditions have been found for the formation of the heteroligand complex. It is shown that Zr (IV) ions are involved in coordination, giving the compound (Zr (DAPM) (HR) 2)/sup 2 -/. A method has been developed for the photometric determination of (0.202.0).10/sup -5/ M solutions of zirconium, and this has been used for the analysis of process water from the Rovensk nuclear power station.

  1. Modelling zirconium hydrides using the special quasirandom structure approach.

    PubMed

    Wang, H; Chroneos, A; Jiang, C; Schwingenschlögl, U

    2013-05-28

    The study of the structure and properties of zirconium hydrides is important for understanding the embrittlement of zirconium alloys used as cladding in light water nuclear reactors. Simulation of the defect processes is complicated due to the random distribution of the hydrogen atoms. We propose the use of the special quasirandom structure approach as a computationally efficient way to describe this random distribution. We have generated six special quasirandom structure cells based on face centered cubic and face centered tetragonal unit cells to describe ZrH(2-x) (x = 0.25-0.5). Using density functional theory calculations we investigate the mechanical properties, stability, and electronic structure of the alloys. PMID:23588997

  2. Magnetic susceptibility and Faraday rotation in zirconium based fluoride glasses

    NASA Astrophysics Data System (ADS)

    Hall, D. B.; Vogel, K. A.; Schroeder, J.

    1998-07-01

    The temperature dependences of the d.c. magnetic susceptibility and Verdet constant in two zirconium based fluoride glasses have been studied. One sample has as a minor constituent dysprosium which has a large magnetic moment that dominates the material's magnetic character. The second sample, containing a small amount of europium, shows both Van Vleck paramagnetism and a Curie-Weiss behaviour. The Curie-Weiss character is believed to come from small amounts of 0953-8984/10/26/024/img6 and/or 0953-8984/10/26/024/img7 produced during the sample's manufacturing process. An upper limit is placed on the amount of magnetic zirconium in the material.

  3. Nitrates

    MedlinePlus

    ... or interactions with other medicines and vitamin or herbal supplements. This information should not be used as medical ... your doctor about every medicine and vitamin or herbal supplement that you are taking, so he or she ...

  4. Polyimide nanocomposites based on cubic zirconium tungstate

    NASA Astrophysics Data System (ADS)

    Ramasubramanian Sharma, Gayathri

    2009-12-01

    In this research, cubic zirconium tungstate (ZrW2O8) was used as a filler to reduce the CTE of polyimides (PI), and the effect of ZrW2O8 nanoparticles on the bulk polymer properties was studied. Polyimides are high performance polymers with exceptional thermal stability, and there is a need for PIs with low CTEs for high temperature applications. The nanofiller, cubic ZrW2O8, is well known for its isotropic negative thermal expansion (NTE) over a wide temperature range from -272.7 to 777°C. The preparation of nanocomposites involved the synthesis of ZrW 2O8 nanofiller, engineering the polymer-filler interface using linker groups and optimization of processing strategies to prepare free-standing PI nanocomposite films. A hydrothermal method was used to synthesize ZrW 2O8 nanoparticles. Polyimide-ZrW2O8 interface interaction was enhanced by covalently bonding linker moieties to the surface of ZrW2O8 nanoparticles. Specifically, ZrW 2O8 nanoparticles were functionalized with two different linker groups: (1) a short aliphatic silane, and (2) low molecular weight PI. The surface functionalization was confirmed using X-ray photoelectron spectroscopy and thermal gravimetric analysis (TGA). Reprecipitation blending was used to prepare the freestanding PI-ZrW2O8 nanocomposite films with up to 15 volume% filler loading. SEM images showed the improvements in polymer-filler wetting behavior achieved using interface engineering. SEM images indicated that there was better filler dispersion in the PI matrix using reprecipitation blending, compared to the filler dispersion achieved in the nanocomposites prepared using conventional blending technique. The structure-property relationships in PI-ZrW2O8 nanocomposites were investigated by studying the thermal degradation, glass transition, tensile and thermal expansion properties of the nanocomposites. The properties were studied as a function of filler loading and interface linker groups. Addition of ZrW2O8 nanoparticles did not alter the thermal degradation and glass transition temperatures of the base PI. The addition of ZrW2O8 nanoparticles increased the Young's modulus of the polymer, indicating the stiffening of polyimide matrix. The modulus showed a steady increase with increase in filler loading. The increase was higher for nanocomposites with engineered interface due to the efficient load transfer achieved through the presence of linker groups. The strain at yield and the tensile strength decreased with the addition of ZrW2O8. The experimental results for the moduli of nanocomposites were compared with moduli predicted using theoretical models. The results for the nanocomposites with unmodified ZrW2O8 followed Hashin-Shtrikman (H-S) lower bound, which showed the presence of mechanical interactions between the polymer and filler. The moduli for nanocomposites with engineered interface fell between the H-S bounds, demonstrating the stiffening of PI matrix through efficient load transfer. The addition of ZrW2O8 reduced the in-plane CTE of the base PI at all loadings. The CTE of the nanocomposites decreased steadily with an increase in the filler loading. With the addition of 15 volume% APT-ZrW 2O8, the CTE of the base PI reduced from 64.3 +/- 1.3 ppm/°C to 51.9 +/- 0.9 ppm/°C. In other words, the CTE of the base PI was reduced by around 22% with the addition of ZrW2O 8 at 15 volume% loading. The CTE values were comparable for all samples at similar loadings irrespective of the interface groups. The experimental results for the CTEs of nanocomposites were compared with CTEs predicted using theoretical models. The data followed the Schapery upper bound, which was consistent with the results observed for the moduli data. The effect of ZrW2O8 particle size on the bulk properties of the polyimide was also investigated. The CTE of composites with micron particles at 5 volume% was comparable to that obtained for nanocomposites at the same filler loading. But, there were significant differences in the mechanical strength of composites. PI composites with ZrW2O 8 micron particles were extremely brittle and readily crumbled at as low as 5 volume%, while composites with ZrW2O8 nanofiller had good mechanical strength up to 15 volume% filler loading. The nanoparticles of ZrW2O8 exhibited autohydration under ambient conditions. Cubic ZrW2O8 nanoparticles continued to hydrate to the same extent even after incorporation into the polyimide matrix. Surface functionalization of ZrW2O8 with silane and PI oligomers did not alter the hydration behavior of ZrW 2O8. (Abstract shortened by UMI.)

  5. The effect of zirconium on the cyclic oxidation of NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.; Khan, A. S.; Lowell, C. E.

    1981-01-01

    This paper examines results with cyclic oxidation tests of Ni(9-20) Cr(15-30) Al-(x)Zr alloys carried out at 1100 C and 1200 C in static air. The concentration of zirconium varies from 0 to 0.63 atomic percent. Significant aluminum penetration is found in metallographic and electron microscopic examination of oxidized surfaces. Small amounts of zirconium lead to minimal penetration, and with increased zirconium content pronounced oxide penetration is observed.

  6. The Arabidopsis NRG2 Protein Mediates Nitrate Signaling and Interacts with and Regulates Key Nitrate Regulators.

    PubMed

    Xu, Na; Wang, Rongchen; Zhao, Lufei; Zhang, Chengfei; Li, Zehui; Lei, Zhao; Liu, Fei; Guan, Peizhu; Chu, Zhaohui; Crawford, Nigel M; Wang, Yong

    2016-02-01

    We show that NITRATE REGULATORY GENE2 (NRG2), which we identified using forward genetics, mediates nitrate signaling in Arabidopsis thaliana. A mutation in NRG2 disrupted the induction of nitrate-responsive genes after nitrate treatment by an ammonium-independent mechanism. The nitrate content in roots was lower in the mutants than in the wild type, which may have resulted from reduced expression of NRT1.1 (also called NPF6.3, encoding a nitrate transporter/receptor) and upregulation of NRT1.8 (also called NPF7.2, encoding a xylem nitrate transporter). Genetic and molecular data suggest that NRG2 functions upstream of NRT1.1 in nitrate signaling. Furthermore, NRG2 directly interacts with the nitrate regulator NLP7 in the nucleus, but nuclear retention of NLP7 in response to nitrate is not dependent on NRG2. Transcriptomic analysis revealed that genes involved in four nitrogen-related clusters including nitrate transport and response to nitrate were differentially expressed in the nrg2 mutants. A nitrogen compound transport cluster containing some members of the NRT/PTR family was regulated by both NRG2 and NRT1.1, while no nitrogen-related clusters showed regulation by both NRG2 and NLP7. Thus, NRG2 plays a key role in nitrate regulation in part through modulating NRT1.1 expression and may function with NLP7 via their physical interaction. PMID:26744214

  7. Oxidation characteristics of molybdenum-zirconium oxide cermets

    NASA Technical Reports Server (NTRS)

    Heitzinger, B.

    1984-01-01

    The oxidation of molybdenum is affected by the factors of temperature, the oxygen pressure in the oxidizing atmosphere, and the time of exposure. Studies of the oxidation characteristics of Mo show that the oxidation rate increases strongly when the temperature exceeds 600 C. Investigations of the behavior of cermets with various percentages of zirconium oxide are discussed, taking into account oxidation conditions at temperatures under and above the melting point of molybdenum trioxide.

  8. New Zirconium Phosphate Fluorides: Hydrothermal Synthesis and Crystal Structures

    NASA Astrophysics Data System (ADS)

    Wloka, M.; Troyanov, S. I.; Kemnitz, E.

    1998-02-01

    A series of zirconium phosphate fluorides were synthesized and structurally characterized using different amines as templates. The compounds have the general formulas [ amH n] 1/ n[Zr 2(HPO 4)(PO 4) 2F]·H 2O (1, am=ethylenediamine, n=2; 2. am= N-methylethylenediamine, n=2; 3, am=1,3-diaminopropane, n=2; 4, am=diethylenetriamine, n=3) and [ amH 2] 0.5[Zr 2(HPO 4) 2(PO 4)F 2]·0.5H 2O (5, am= N, N, N', N'-tetramethylethylenediamine). In the structures of 2-4 with a Zr:F ratio of 2:1, there exists a three-dimensional arrangement of zirconium octahedra (one ZrO 6and one ZrO 5F) and phosphate tetrahedra (two PO 4and one HPO 4) connected via common oxygen atoms, whereas fluorine atoms and OH groups are terminal. These compounds crystallize in the "ZrPO-1" structure type, which contains channels along the baxis formed by eight-membered rings of alternating PO 4tetrahedra and ZrO 6or ZrO 5F octahedra, respectively. The protonated disordered templates occupy the channels. Half the water molecules are situated in the positions alternatively left free by the disordered templates and the other half are bonded via hydrogen bridges to the terminal OH groups of the HPO 4tetrahedra. In contrast, the structure of 5 reveals a Zr:F ratio of 1:1, consequently forming a layer structure. The layers formed by ZrO 5F octahedra and PO 4or HPO 4tetrahedra, respectively, are linked by hydrogen bridges of type O-H···F and by weak H bonds over the protonated template. The similarities in connectivity pattern between Zr octahedra and P tetrahedra in all known zirconium phosphate fluorides and some zirconium phosphates are discussed.

  9. Phylogenomics of Mycobacterium Nitrate Reductase Operon.

    PubMed

    Huang, Qinqin; Abdalla, Abualgasim Elgaili; Xie, Jianping

    2015-07-01

    NarGHJI operon encodes a nitrate reductase that can reduce nitrate to nitrite. This process enhances bacterial survival by nitrate respiration under anaerobic conditions. NarGHJI operon exists in many bacteria, especially saprophytic bacteria living in soil which play a key role in the nitrogen cycle. Most actinomycetes, including Mycobacterium tuberculosis, possess NarGHJI operons. M. tuberculosis is a facultative intracellular pathogen that expands in macrophages and has the ability to persist in a non-replicative form in granuloma lifelong. Nitrogen and nitrogen compounds play crucial roles in the struggle between M. tuberculosis and host. M. tuberculosis can use nitrate as a final electron acceptor under anaerobic conditions to enhance its survival. In this article, we reviewed the mechanisms regulating nitrate reductase expression and affecting its activity. Potential genes involved in regulating the nitrate reductase expression in M. tuberculosis were identified. The conserved NarG might be an alternative mycobacterium taxonomic marker. PMID:25980349

  10. Methemoglobinemia by cerium nitrate poisoning.

    PubMed

    Attof, Rachid; Rachid, Attof; Magnin, Christophe; Christophe, Magnin; Bertin-Maghit, Marc; Marc, Bertin-Maghit; Olivier, Laure; Laure, Olivier; Tissot, Sylvie; Sylvie, Tissot; Petit, Paul; Paul, Petit

    2006-12-01

    Cerium nitrate is a topical antiseptic used with silver sulfadiazine (Flammacerium) for the treatment of serious burns. This topical agent can induce methemoglobinemia, but no cases have been reported in the recent literature. In this article, we present the case of a 16-year old girl, with third-degree burns over 95% of her body. After daily dressings of Flammacerium, on the sixth day she developed a bluish skin coloring. When tested for methemoglobinemia, levels of 31.8% were found. These returned to normal after classic treatment with Methylene blue. PMID:17027160

  11. SEPARATION OF PLUTONIUM IONS FROM SOLUTION BY ADSORPTION ON ZIRCONIUM PYROPHOSPHATE

    DOEpatents

    Stoughton, R.W.

    1961-01-31

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

  12. Laves intermetallics in stainless steel-zirconium alloys

    SciTech Connect

    Abraham, D.P.; McDeavitt, S.M.; Richardson, J.W. Jr.

    1997-05-01

    Laves intermetallics have a significant effect on properties of metal waste forms being developed at Argonne National Laboratory. These waste forms are stainless steel-zirconium alloys that will contain radioactive metal isotopes isolated from spent nuclear fuel by electrometallurgical treatment. The baseline waste form composition for stainless steel-clad fuels is stainless steel-15 wt.% zirconium (SS-15Zr). This article presents results of neutron diffraction measurements, heat-treatment studies and mechanical testing on SS-15Zr alloys. The Laves intermetallics in these alloys, labeled Zr(Fe,Cr,Ni){sub 2+x}, have both C36 and C15 crystal structures. A fraction of these intermetallics transform into (Fe,Cr,Ni){sub 23}Zr{sub 6} during high-temperature annealing; the authors have proposed a mechanism for this transformation. The SS-15Zr alloys show virtually no elongation in uniaxial tension, but exhibit good strength and ductility in compression tests. This article also presents neutron diffraction and microstructural data for a stainless steel-42 wt.% zirconium (SS-42Zr) alloy.

  13. Continuous ion exchange separation of zirconium and hafnium

    SciTech Connect

    Begovich, J.M.; Sisson, W.G.

    1981-01-01

    A pressurized continuous annular chromatograph (CAC) has been developed for truly continuous ion exchange preparative separations. This device utilizes a slowly rotating annular bed of sorbent material, fixed multiple feed points, and fixed withdrawal locations. Most of our investigations have been performed with a 28-cm-diam by 60-cm-long CAC, but a larger model has recently been designed and constructed. A detailed study has been made of the separation of copper, nickel, and cobalt components from a simulated carbonate leach liquor of the Caron process for recovering nickel and cobalt from laterite ores. Recent studies have investigated the ion exchange separation of zirconium and hafnium from a sulfate feed solution. Nuclear reactor-grade zirconium, containing < 0.01 wt % hafnium, and hafnium, containing < 1% zirconium, have been continuously prepared using cation exchange resin in the pressurized CAC. This device, because of its continuous feed and product withdrawal, its adaptability to largescale operations, and its ability to separate many components, is expected to make chromatography a more competitive process in the industrial sector.

  14. Trend Analyses of Nitrate in Danish Groundwater

    NASA Astrophysics Data System (ADS)

    Hansen, B.; Thorling, L.; Dalgaard, T.; Erlandsen, M.

    2012-04-01

    This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark. Are the Danish groundwater monitoring strategy obtimal for detection of nitrate trends? Will the nitrate concentrations in Danish groundwater continue to decrease or are the Danish nitrate concentration levels now appropriate according to the Water Framework Directive?

  15. Groundwater nitrate contamination: Factors and indicators

    PubMed Central

    Wick, Katharina; Heumesser, Christine; Schmid, Erwin

    2012-01-01

    Identifying significant determinants of groundwater nitrate contamination is critical in order to define sensible agri-environmental indicators that support the design, enforcement, and monitoring of regulatory policies. We use data from approximately 1200 Austrian municipalities to provide a detailed statistical analysis of (1) the factors influencing groundwater nitrate contamination and (2) the predictive capacity of the Gross Nitrogen Balance, one of the most commonly used agri-environmental indicators. We find that the percentage of cropland in a given region correlates positively with nitrate concentration in groundwater. Additionally, environmental characteristics such as temperature and precipitation are important co-factors. Higher average temperatures result in lower nitrate contamination of groundwater, possibly due to increased evapotranspiration. Higher average precipitation dilutes nitrates in the soil, further reducing groundwater nitrate concentration. Finally, we assess whether the Gross Nitrogen Balance is a valid predictor of groundwater nitrate contamination. Our regression analysis reveals that the Gross Nitrogen Balance is a statistically significant predictor for nitrate contamination. We also show that its predictive power can be improved if we account for average regional precipitation. The Gross Nitrogen Balance predicts nitrate contamination in groundwater more precisely in regions with higher average precipitation. PMID:22906701

  16. Sampling of nitrates in ambient air

    NASA Astrophysics Data System (ADS)

    Appel, B. R.; Tokiwa, Y.; Haik, M.

    Methods for the measurement of nitric acid, particulate nitrate and total inorganic nitrate (i.e. HNO 3 plus particulate nitrate) are compared using atmospheric samples from the Los Angeles Basin. Nitric acid was measured by (1) the nitrate collected on nylon or NaCl-impregnated cellulose filters after removal of particulate matter with Teflon prefilters, (2) long-path Fourier transform infrared spectroscopy (FTIR) performed by a collaborating investigator, and (3) the difference between total inorganic nitrate (TIN) and particulate nitrate (PN). TIN was measured by the sum of the nitrate collected with a Teflon prefilter and nylon or NaCl-impregnated after-filter. PN was measured by the nitrate able to penetrate a diffusion dénuder coated to remove acidic gases (e.g. HNO 3). Losses of nitrate from Teflon prefilters were determined by comparing the nitrate retained by these filters to the nitrate penetrating the acid gas denuder. TIN and the nitrate collected with glass fiber filters were compared to assess the origin of the artifact particulate nitrate on the latter. Nitric acid measurements using nylon or NaCl-impregnated after-filters were substantially higher than those by the difference technique. This correlated with losses of nitrate from the Teflon prefilters, which exceeded 50 % at high ambient temperature and low relative humidity. Nitric acid by the difference method exceeded that by FTIR by, on average, 20 %. Thus errors inferred in HNO 3 measurements by comparison to the difference measurements are considered minimum values. The high values for HNO 3 by the difference method are consistent with the partial loss of PN in the acid gas denuder. However, no loss of 0.1 μm to 3 μm diameter NH 4NO 3 particles was observed. Thus, if significant, such loss is restricted to coarse particulate nitrate. Heating the filter samplers was shown to increase sampling errors. Nitrate results obtained in short-term, low volume sampling with Gelman A glass fiber filters approximated those with the TIN samplers. Accordingly, these glass fiber filters retained essentially all the gaseous nitric acid sampled.

  17. Phase Diagram of Ammonium Nitrate

    NASA Astrophysics Data System (ADS)

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-06-01

    Ammonium Nitrate (AN) has often been subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood - resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety, in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN, in different chemical environments, at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 15 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 673 K. The present study has been supported by the U.S. DHS under Award Number 2008-ST-061-ED0001.

  18. Peroxyacetyl nitrate and peroxypropionyl nitrate in Porto Alegre, Brazil

    NASA Astrophysics Data System (ADS)

    Grosjean, Eric; Grosjean, Daniel; Woodhouse, Luis F.; Yang, Yueh-Jiun

    For 41 days between 25 May 1996 and 27 March 1997, peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN) have been measured by electron capture gas chromatography at Santa Rita near Porto Alegre, RS, Brazil, where light-duty vehicles used either ethanol or a gasoline-MTBE blend. Daily maximum concentrations ranged from 0.19 to 6.67 ppb for PAN and 0.06 to 0.72 ppb for PPN. Linear regression of maximum PPN vs. maximum PAN yielded a slope of 0.105±0.004 ( R2=0.974). Diurnal variations of ambient PAN often followed those of ozone with respect to time of day but not with respect to amplitude. This was reflected in the large relative standard deviations associated with the study-averaged PAN/ozone concentration ratio, 0.037±0.105 (ppb/ppb, n=789) and the maximum PAN/maximum ozone concentration ratio, 0.028±0.015 (ppb/ppb, range 0.005-0.078, n=41). On several days PAN accounted for large fractions of the total ambient NO x in the late morning and afternoon hours, e.g., PAN/NO x⩽0.58 and PAN/(NO x-NO) ⩽0.76 on 27 March 1997. The amount of PAN lost by thermal decomposition (TPAN) was comparable in magnitude to that present in ambient air. The ratios TPAN/(PAN+TPAN) were up to 0.53, 0.67 and 0.64 during the warm afternoons of 25, 26 and 27 March 1997, respectively. The highest calculated value of TPAN was 5.6 ppb on 27 March 1997. On that day the 24 h-averaged value of TPAN (1.01 ppb) was nearly the same as that of PAN (1.09 ppb). Using computer kinetic modeling (SAPRC 97 chemical mechanism) and sensitivity analysis of VOC incremental reactivity, we ranked VOC present in Porto Alegre ambient air for their importance as precursors to PAN and to PPN. Using as input data the averages of VOC concentrations measured in downtown Porto Alegre during the ca. 1 yr period March 1996-April 1997, we calculated that the most important precursors to PAN and PPN were the SAPRC 97 model species ARO2 (which includes the aromatics xylenes, trimethylbenzenes, ethyltoluenes, etc.), which accounted for ca. 17% of the total PAN and total PPN formation potentials. Overall, the results indicate a major role for aromatics and alkenes and a minor role for acetaldehyde and ethanol as precursors to peroxyacyl nitrates in the Porto Alegre urban area.

  19. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed with..., blasting, type B, and Explosives, blasting, type E, Division 1.5 compatibility group D. (f) No...

  20. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed with..., blasting, type B, and Explosives, blasting, type E, Division 1.5 compatibility group D. (f) No...

  1. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed with..., blasting, type B, and Explosives, blasting, type E, Division 1.5 compatibility group D. (f) No...

  2. REDUCTION OF NITRATE THROUGH THE USE OF NITRATE REDUCTASE FOR THE SMARTCHEM AUTOANALYZER

    EPA Science Inventory

    The standard method for the determination of nitrate in drinking water, USEPA Method 353.2 “Determination of Nitrate-Nitrite by Automated Colorimetry,” employs cadmium as the reductant for the conversion of nitrate to nitrite. The nitrite is then analyzed colorimetrically by way ...

  3. The NreA protein functions as a nitrate receptor in the staphylococcal nitrate regulation system.

    PubMed

    Niemann, Volker; Koch-Singenstreu, Mareike; Neu, Ancilla; Nilkens, Stephanie; Götz, Friedrich; Unden, Gottfried; Stehle, Thilo

    2014-04-01

    Staphylococci are able to use nitrate as an alternative electron acceptor during anaerobic respiration. The regulation of energy metabolism is dependent on the presence of oxygen and nitrate. Under anaerobic conditions, staphylococci employ the nitrate regulatory element (Nre) for transcriptional activation of genes involved in reduction and transport of nitrate and nitrite. Of the three proteins that constitute the Nre system, NreB has been characterized as an oxygen sensor kinase and NreC has been characterized as its cognate response regulator. Here, we present structural and functional data that establish NreA as a new type of nitrate receptor. The structure of NreA with bound nitrate was solved at 2.35Å resolution, revealing a GAF domain fold. Isothermal titration calorimetry experiments showed that NreA binds nitrate with low micromolar affinity (KD=22μM). Two crystal forms for NreA were obtained, with either bound nitrate or iodide. While the binding site is hydrophobic, two helix dipoles and polar interactions contribute to specific binding of the ions. The expression of nitrate reductase (NarGHI) was examined using a narG-lip (lipase) reporter gene assay in vivo. Expression was regulated by the presence of NreA and nitrate. Structure-guided mutations of NreA reduced its nitrate binding affinity and also affected the gene expression, thus providing support for the function of NreA as a nitrate receptor. PMID:24389349

  4. Safety in the Chemical Laboratory: Nitric Acid, Nitrates, and Nitro Compounds.

    ERIC Educational Resources Information Center

    Bretherick, Leslie

    1989-01-01

    Discussed are the potential hazards associated with nitric acid, inorganic and organic nitrate salts, alkyl nitrates, acyl nitrates, aliphatic nitro compounds, aromatic nitro compounds, and nitration reactions. (CW)

  5. Synthesis and characterization of mixed Fe-Cr oxide pillared {alpha}-zirconium phosphate materials

    SciTech Connect

    Perez-Reina, F.J.; Olivera-Pastor, P.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.

    1996-02-15

    Mixed Fe/Cr hydroxyacetate oligomers ranging in composition from 90/10 to 10/90 have been prepared by mixing Fe{sup 3+} and Cr{sup 3+} nitrate solutions and then adding n-propylammonium acetate up to an acetate/Cr{sup 3+} ratio of 2.8 and pH 4. The oligomers were intercalated into colloidal {alpha}-zirconium phosphate or precipitated with excess n-propylamine. The precipitates are all amorphous and show differential thermal behavior in comparison with the intercalates. Upon calcination in air, the precipitates become crystalline, showing the characteristic XRD peaks of mixed Fe/Cr oxides. These mixed oxides present unusually high BET surface areas (up to 276 m {sup 2}{center_dot}g{sup {minus}1}), especially those with low Fe/Cr ratios. The intercalates are poorly crystalline or amorphous at room temperature and upon calcination at 400{degrees}C in air or under N{sub 2}, which indicates that there is no oxide segregation from the interlayers. From these results it is suggested that mixed Fe/Cr oxides are cross-linked to the phosphate layer, forming a pillared structure. Significantly, the mixed oxides segregated from the phosphate surface at 1000{degrees}C present XRD patterns identical to the mixed oxides obtained from the precipitates with the same Fe/Cr ratios. The pillared materials show high BET surface areas, from 200 to 306 m{sup 2}/g, and narrow pore size distributions with pore radius ranging from 8.5 to 13.8 {Angstrom}. XPS analysis reveals a higher affinity of the phosphate surface for Cr{sup 3+} at high Fe/Cr ratios from 70/30 to 90/10. In these samples the partial oxidation of Cr(III) to Cr(VI) was observed in the XPS spectra, in spite of the materials being calcined under N{sub 2}.

  6. Nitrate Reduction Functional Genes and Nitrate Reduction Potentials Persist in Deeper Estuarine Sediments. Why?

    PubMed Central

    Papaspyrou, Sokratis; Smith, Cindy J.; Dong, Liang F.; Whitby, Corinne; Dumbrell, Alex J.; Nedwell, David B.

    2014-01-01

    Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are processes occurring simultaneously under oxygen-limited or anaerobic conditions, where both compete for nitrate and organic carbon. Despite their ecological importance, there has been little investigation of how denitrification and DNRA potentials and related functional genes vary vertically with sediment depth. Nitrate reduction potentials measured in sediment depth profiles along the Colne estuary were in the upper range of nitrate reduction rates reported from other sediments and showed the existence of strong decreasing trends both with increasing depth and along the estuary. Denitrification potential decreased along the estuary, decreasing more rapidly with depth towards the estuary mouth. In contrast, DNRA potential increased along the estuary. Significant decreases in copy numbers of 16S rRNA and nitrate reducing genes were observed along the estuary and from surface to deeper sediments. Both metabolic potentials and functional genes persisted at sediment depths where porewater nitrate was absent. Transport of nitrate by bioturbation, based on macrofauna distributions, could only account for the upper 10 cm depth of sediment. A several fold higher combined freeze-lysable KCl-extractable nitrate pool compared to porewater nitrate was detected. We hypothesised that his could be attributed to intracellular nitrate pools from nitrate accumulating microorganisms like Thioploca or Beggiatoa. However, pyrosequencing analysis did not detect any such organisms, leaving other bacteria, microbenthic algae, or foraminiferans which have also been shown to accumulate nitrate, as possible candidates. The importance and bioavailability of a KCl-extractable nitrate sediment pool remains to be tested. The significant variation in the vertical pattern and abundance of the various nitrate reducing genes phylotypes reasonably suggests differences in their activity throughout the sediment column. This raises interesting questions as to what the alternative metabolic roles for the various nitrate reductases could be, analogous to the alternative metabolic roles found for nitrite reductases. PMID:24728381

  7. COMPARTMENTAL MODEL OF NITRATE RETENTION IN STREAMS

    EPA Science Inventory

    A compartmental modeling approach is presented to route nitrate retention along a cascade of stream reach sections. A process transfer function is used for transient storage equations with first order reaction terms to represent nitrate uptake in the free stream, and denitrifica...

  8. NITRATE CONTAMINATION OF GROUND WATER (GW-761)

    EPA Science Inventory

    The occurrence of nitrate and related compounds in ground water is discussed from the perspectives of its natural as well as anthropogenic origins. A brief explanation of the nitrogen cycle touches on the production as well as utilization of ammonia, nitrite, nitrate, and nitrog...

  9. HEALTH EFFECTS OF NITRATES IN WATER

    EPA Science Inventory

    A multi faceted study of the health effects of nitrate in drinking water using epidemiological and toxicological techniques is reported. The results of the epidemiological studies indicate that infants consuming appreciable amounts of water high in nitrates in the form of powdere...

  10. 76 FR 62311 - Ammonium Nitrate Security Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-07

    ... FR 64280 (advance notice of proposed rulemaking); 76 FR 46908 (notice of proposed rulemaking... Program Web site in mid-October at http://www.dhs.gov/ files/ ] programs/ammonium-nitrate-security-program...; ] DEPARTMENT OF HOMELAND SECURITY Office of the Secretary 6 CFR Part 31 RIN 1601-AA52 Ammonium Nitrate...

  11. 76 FR 46907 - Ammonium Nitrate Security Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-03

    ... Federal Bureau of Investigation FR Federal Register HMR Hazardous Materials Regulations HMT Hazardous... ``Secure Handling of Ammonium Nitrate Program'' on October 29, 2008. See 73 FR 64280. The ANPRM solicited... interacting with state and local governments regarding ammonium nitrate security. ] See 73 FR 64280,...

  12. The contributions of nitrate uptake and efflux to isotope fractionation during algal nitrate assimilation

    NASA Astrophysics Data System (ADS)

    Karsh, K. L.; Trull, T. W.; Sigman, D. M.; Thompson, P. A.; Granger, J.

    2014-05-01

    In order to strengthen environmental application of nitrate N and O isotopes, we measured the N and O isotopic fractionation associated with cellular nitrate uptake and efflux in the nitrate-assimilating marine diatom Thalassiosira weissflogii. We isolated nitrate uptake and efflux from nitrate reduction by growing the cells in the presence of tungsten, which substitutes for molybdenum in assimilatory nitrate reductase, yielding an inactive enzyme. After growth on ammonium and then N starvation, cells were exposed to nitrate. Numerical models fit to the evolution of intracellular nitrate concentration and N and O isotopic composition yielded distinct N isotope effects (15ɛ) for nitrate uptake and nitrate efflux (2.0 ± 0.3‰ and 1.2 ± 0.4‰, respectively). The O isotope effects (18ɛ) for nitrate uptake and nitrate efflux were indistinguishable (2.8 ± 0.6‰), yielding a ratio of O to N isotopic fractionation for uptake of 1.4 ± 0.4 and for efflux of 2.3 ± 0.9. The 15ɛ for nitrate uptake can account for at most 40% of the organism-level N isotope effect (15ɛorg) measured in laboratory studies of T. weissflogii and in the open ocean (typically 5‰ or greater). This observation supports previous evidence that most isotope fractionation during nitrate assimilation is due to intracellular nitrate reduction, with nitrate efflux allowing the signal to be communicated to the environment. An O to N fractionation ratio (18ɛorg:15ɛorg) of ˜1 has been measured for nitrate assimilation in algal cultures and linked to the N and O isotope effects of nitrate reductase. Our results suggest that the ratios of O to N fractionation for both nitrate uptake and efflux may be distinct from a ratio of 1, to a degree that could cause the net 18ɛorg:15ɛorg to rise appreciably above 1 when 15ɛorg is low (e.g., yielding a ratio of 1.1 when 15ɛorg is 5‰). However, field and culture studies have consistently measured nearly equivalent fractionation of N and O isotopes in association with low isotope effects, calling for isotopic studies of nitrate transport by other phytoplankton strains.

  13. Extraction of rare-earth(III) nitrates by trialkylmethylammonium nitrate from multicomponent solutions

    SciTech Connect

    Pyartman, A.K.; Kopyrin, A.A.; Puzikov, E.A.

    1994-05-20

    Extraction of rare-earth metal(III) (REM) [praseodymium-lutetium, yttrium(III)] nitrates by solutions of trialkylmethylammonium nitrate in kerosene (0.4-1.0 M) was studied. It was established that di- and trisolvates are formed in the organic phase. Extraction constants were determined. Physicochemical and mathematical models were developed to describe the extraction of REM(III) nitrates from binary and multicomponent aqueous solutions. The range of REM nitrate concentrations in the aqueous providing optimal conditions for extraction separation of REM by trialkylmethylammonium nitrate solutions in kerosene was established.

  14. PREPARATION OF DIBASIC ALUMINUM NITRATE

    DOEpatents

    Gresky, A.T.; Nurmi, E.O.; Foster, D.L.; Wischow, R.P.; Savolainen, J.E.

    1960-04-01

    A method is given for the preparation and recovery of basic aluminum nltrates having an OH: Al ratio of at least two, comprising two steps. First, metallic aluminum is dissolved in aqueous Al(NO/sub 3/)/sub 3/, in the presence of a small quantity of elemental or ionic mercury, to increase its Al: NO/sub 3/ ratio into the range 1 to 1.2. The resulting aqueous solution is then added to an excess of a special organic solvent, typically a mixture of five parts methanol and six parts diethyl ether, whereupon the basic aluminum nitrate, e.g. Al/sub 6/(OH)/sub 13/-(NO/sub 3/)/sub 5/, recoverably precipitates.

  15. Phase diagram of ammonium nitrate.

    PubMed

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-12-01

    Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO-AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N2, N2O, and H2O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV' transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C. PMID:24320387

  16. Global distribution of peroxyacetyl nitrate

    NASA Technical Reports Server (NTRS)

    Singh, H. B.; Salas, L. J.; Viezee, W.

    1986-01-01

    Peroxyacetyl nitrate (PAN) atmospheric concentration samples were collected hourly from an ocean vessel 50 mi off the continental coast traveling from Seattle to Chile in 1984. Air concentration data for PAN and light hydrocarbons (LHC) were also taken by aircraft in the same period over Wyoming and Colorado and over the eastern Pacific. The PAN concentrations were higher and more variable in the Northern Hemisphere than in the Southern Hemisphere, increased with altitude, and were higher in the winter than in summer. The summer PAN concentrations were higher in the continental troposphere than in the marine troposphere. The results show that photochemical models of the atmosphere which do not account for the reaction between nonmethane hydrocarbons and PAN will probably overestimate the abundances of NO(x) and HNO3. The collection of further PAN concentration data is recommended as a means to characterizing the moderating role of PAN in the photochemistry of the troposphere.

  17. Nitrate removal from drinking water -- Review

    SciTech Connect

    Kapoor, A.; Viraraghavan, T.

    1997-04-01

    Nitrate concentrations in surface water and especially in ground water have increased in Canada, the US, Europe, and other areas of the world. This trend has raised concern because nitrates cause methemoglobiinemia in infants. Several treatment processes including ion exchange, biological denitrification, chemical denitrification, reverse osmosis, electrodialysis, and catalytic denitrification can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation. Available technical data, experience, and economics indicate that ion exchange and biological denitrification are more acceptable for nitrate removal than reverse osmosis. Ion exchange is more viable for ground water while biological denitrification is the preferred alternative for surface water. This paper reviews the developments in the field of nitrate removal processes.

  18. 40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for...

  19. 40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for...

  20. 40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for...

  1. 40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for...

  2. 40 CFR 721.10152 - Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-, hydrolysis products with alkanol zirconium(4+) salt and silica, acetates (generic). 721.10152 Section 721... Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4+) salt and silica... zirconium(4+) salt and silica, acetates (PMN P-07-674) is subject to reporting under this section for...

  3. 70. INTERIOR VIEW OF AMMONIUM NITRATE HOUSE, LOOKING AT AMMONIUM ...

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

    70. INTERIOR VIEW OF AMMONIUM NITRATE HOUSE, LOOKING AT AMMONIUM NITRATE IN STORAGE. APRIL 18, 1919. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  4. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  5. 21 CFR 700.16 - Use of aerosol cosmetic products containing zirconium.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Use of aerosol cosmetic products containing... SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol cosmetic products containing zirconium. (a) Zirconium-containing complexes have been used as an...

  6. 40 CFR 721.10089 - Modified salicylic acid, zirconium complex (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... complex (generic). 721.10089 Section 721.10089 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10089 Modified salicylic acid, zirconium complex (generic). (a) Chemical... as modified salicylic acid, zirconium complex (PMN P-00-552) is subject to reporting under...

  7. Zirconium carbide as an electrocatalyst for the chromous-chromic redox couple

    NASA Technical Reports Server (NTRS)

    Gahn, R. F.; Reid, M. A.; Yang, C. Y. (Inventor)

    1981-01-01

    Zirconium carbide is used as a catalyst in a REDOX cell for the oxidation of chromous ions to chromic ions and for the reduction of chromic ions to chromous ions. The zirconium carbide is coated on an inert electronically conductive electrode which is present in the anode fluid of the cell.

  8. Lithium aluminate/zirconium material useful in the production of tritium

    DOEpatents

    Cawley, W.E.; Trapp, T.J.

    1984-10-09

    A composition is described useful in the production of tritium in a nuclear reactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

  9. Lithium aluminate/zirconium material useful in the production of tritium

    DOEpatents

    Cawley, William E.; Trapp, Turner J.

    1984-10-09

    A composition is described useful in the production of tritium in a nuclear eactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

  10. Lithium aluminate/zirconium material useful in the production of tritium

    DOEpatents

    Cawley, W.E.; Trapp, T.J.

    A composition is described useful in the production of tritium in a nuclear reactor. Lithium aluminate particles are dispersed in a matrix of zirconium. Tritium produced by the reactor of neutrons with the lithium are absorbed by the zirconium, thereby decreasing gas pressure within capsules carrying the material.

  11. Solid-State Coexistance of (Zr12) and (Zr6) Zirconium Oxocarboxylate Clusters

    SciTech Connect

    Malaestean, Lurie; Alici, Meliha Kutluca; Besson, Claire; Ellern, Arkady; Kogerler, Paul

    2013-10-30

    Ligand metathesis, Co(II) coordination, and partial condensation reactions of an archetypal {Zr6} zirconium oxocarboxylate cluster result in the first example of the coexistence of the distinct zirconium oxide frameworks {Zr6O8} and {Zr12O22}. Even minor modifications to the reaction conditions push this apparent equilibrium towards the {Zr6O8}-based product.

  12. Solid-state coexistence of {Zr12} and {Zr6} zirconium oxocarboxylate clusters

    SciTech Connect

    Malaestean, Iurie L.; Alici, Meliha Kutluca; Besson, Claire; Ellern, Arkady; Kogerler, Paul

    2013-10-30

    Ligand metathesis, Co(II) coordination, and partial condensation reactions of an archetypal {Zr6} zirconium oxocarboxylate cluster result in the first example of the coexistence of the distinct zirconium oxide frameworks {Zr6O8} and {Zr12O22}. Even minor modifications to the reaction conditions push this apparent equilibrium towards the {Zr6O8}-based product.

  13. Efficient One-Pot Synthesis of Colloidal Zirconium Oxide Nanoparticles for High-Refractive-Index Nanocomposites.

    PubMed

    Liu, Chao; Hajagos, Tibor Jacob; Chen, Dustin; Chen, Yi; Kishpaugh, David; Pei, Qibing

    2016-02-24

    Zirconium oxide nanoparticles are promising candidates for optical engineering, photocatalysis, and high-κ dielectrics. However, reported synthetic methods for the colloidal zirconium oxide nanoparticles use unstable alkoxide precursors and have various other drawbacks, limiting their wide application. Here, we report a facile one-pot method for the synthesis of colloidally stable zirconium oxide nanoparticles. Using a simple solution of zirconium trifluoroacetate in oleylamine, highly stable zirconium oxide nanoparticles have been synthesized with high yield, following a proposed amidization-assisted sol-gel mechanism. The nanoparticles can be readily dispersed in nonpolar solvents, forming a long-term stable transparent solution, which can be further used to fabricate high-refractive-index nanocomposites in both monolith and thin-film forms. In addition, the same method has also been extended to the synthesis of titanium oxide nanoparticles, demonstrating its general applicability to all group IVB metal oxide nanoparticles. PMID:26824518

  14. Effects of intermetallic particles on the SCC initiation of zirconium alloys

    NASA Astrophysics Data System (ADS)

    Kubo, T.; Wakashima, Y.; Imahashi, H.; Nagai, M.

    1985-06-01

    In order to investigate effects of intermetallic particles on SCC initiation of zirconium alloys, tensile tests were conducted in an iodine atmosphere using zirconium plates with different amounts of impurities, and Zircaloy-2 plates. SCC susceptibility of zirconium increased significantly with its iron content. Even small amounts of iron could form the intermetallic compound ZrFe 2 whose particle size and number increased with iron content. In the case of Zircaloy-2, two different types of ternary compounds were detected, namely Zr(CrFe) 2 and Zr 2(NiFe). Metallographic examinations showed that the particles located at grain boundaries were important sites of SCC initiation in zirconium alloys. The initiation probability increased significantly with the amount of the particles, which supported the strong correlation between SCC susceptibility of zirconium and its iron content.

  15. Factors affecting the stress corrosion cracking susceptibility of zirconium in 90% nitric acid

    SciTech Connect

    Yau, T.L.

    1988-10-01

    U-band, C-ring, and slow strain rate tests were performed to evaluate the effects of texture, stress, surface condition, heat treatments electrochemical potential, and strain rate on stress corrosion cracking (SCC) of zirconium in 90% nitric acid at room temperature. Careful control of texture, surface condition (scratching, cleaning, and oxide coating), and/or applied stress was shown to effectively lead to the prevention of SCC of zirconium in 90% HNO/sub 3/. Heat treating at 760, 880, or 1000 C does not seem to improve the SCC resistance. However, if the potential of zirconium is maintained at 500 mV/sub SCE/ or lower, or 200 ppm of HF is added, zirconium's SCC susceptibility in 90% HNO/sub 3/ is eliminated. When adding HF, zirconium sponge must also be added to avoid corrosion rates.

  16. A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.

    1972-01-01

    A simple analytical procedure is described for accurately and precisely determining the zirconium or hafnium content of molybdenum-base alloys. The procedure is based on the reaction of the reagent Arsenazo III with zirconium or hafnium in strong hydrochloric acid solution. The colored complexes of zirconium or hafnium are formed in the presence of molybdenum. Titanium or rhenium in the alloy have no adverse effect on the zirconium or hafnium complex at the following levels in the selected aliquot: Mo, 10 mg; Re, 10 mg; Ti, 1 mg. The spectrophotometric measurement of the zirconium or hafnium complex is accomplished without prior separation with a relative standard deviation of 1.3 to 2.7 percent.

  17. Fundamental studies into zirconium modified phosphonic acid based ionic membranes

    NASA Astrophysics Data System (ADS)

    Schlichting, Gregory Joseph

    The demand for a sustainable energy economy requires the development of new solid stare electrochemical energy conversion devices. Ionic membranes are the bases for most of these devices. Solid super acids based on zirconium phosphonates show great promise for development into these membranes. Copolymers of vinyl phosphonic acid with zirconium vinyl phosphonate have been synthesized via UV free radical polymerization from immiscible mixtures into amorphous, transparent, water stable, flexible membranes. Ion exchange capacities range from 6 to 10 meq/g corresponding to equivalent weights well below 200 g/mol. A 20wt% loading of the VZP co-monomer is XRD amorphous. It is shown that 1.5 of the 2 protons in the beginning acidic groups are dissociated in the 20wt% VZP loaded ionomer allowing these materials to have high proton conductivities, up to and exceeding 0.1 S cm^-1 at 80°C and 80%RH. Water uptake measurementsshow very little swelling of the material below 70%RH and ca. 1 water per proton at low RH. Proton conductivity under dry conditions, roughly 0.05 S cm-1 with a lambda < 1, indicates that the material conducts protons under limiting hydration conditions and strongly implicates transport by a pure Grotthuss mechanism. Through this work, it has been demonstrated that zirconium vinyl phosphonate can, in fact, be dispersed and incorporated into a polymer to create new, hybrid organic-inorganic ionomers. High conductivities over 0.15 S/cm have been shown for multiple formulations of these ionomers, which is approaching conductivities that are comparable to liquid and molten phosphoric and phosphonic acids. Phosphonic acid functionalization yielded high proton conductivities, however the increased ionic character rendered the ionomer vulnerable to attack from water. Annealing provides a rise in conductivity at 150 degrees Celsius, but shows decreases after heating to 175 degrees Celsius, where the ionomer is obviously starting to degrade.

  18. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    SciTech Connect

    Hollis, Kendall J; Pena, Maria I

    2010-01-01

    Zirconium metal coatings applied by plasma spraying and electrospark deposition (ESD) have been investigated for use as diffusion barrier coatings on low enrichment uranium fuel for research nuclear reactors. The coatings have been applied to both stainless steel as a surrogate and to simulated nuclear fuel uranium-molybdenum alloy substrates. Deposition parameter development accompanied by coating characterization has been performed. The structure of the plasma sprayed coating was shown to vary with transferred arc current during deposition. The structure of ESD coatings was shown to vary with the capacitance of the deposition equipment.

  19. Bulk Hydrides and Delayed Hydride Cracking in Zirconium Alloys

    NASA Astrophysics Data System (ADS)

    Tulk, Eric F.

    Zirconium alloys are susceptible to engineering problems associated with the uptake of hydrogen throughout their design lifetime in nuclear reactors. Understanding of hydrogen embrittlement associated with the precipitation of brittle hydride phases and a sub-critical crack growth mechanism known as Delayed Hydride Cracking (DHC) is required to provide the engineering justifications for safe reactor operation. The nature of bulk zirconium hydrides at low concentrations (< 100 wt. ppm) is subject to several contradictory descriptions in the literature associated with the stability and metastability of gamma-phase zirconium hydride. Due to the differing volume expansions (12-17%) and crystallography between gamma and delta hydride phases, it is suggested that the matrix yield strength may have an effect on the phase stability. The present work indicated that although yield strength can shift the phase stability, other factors such as microstructure and phase distribution can be as or more important. This suggests that small material differences are the reason for the literature discrepancies. DHC is characterised by the repeated precipitation, growth, fracture of brittle hydride phases and subsequent crack arrest in the ductile metal. DHC growth is associated primarily the ability of hydrogen to diffuse under a stress induced chemical potential towards a stress raiser. Knowledge of the factors controlling DHC are paramount in being able to appropriately describe DHC for engineering purposes. Most studies characterise DHC upon cooling to the test temperature. DHC upon heating has not been extensively studied and the mechanism by which it occurs is somewhat controversial in the literature. This work shows that previous thermo-mechanical processing of hydrided zirconium can have a significant effect on the dissolution behaviour of the bulk hydride upon heating. DHC tests with gamma-quenched, furnace cooled-delta and reoriented bulk hydrides upon heating and DHC upon cooling suggest that the amount of hydrogen in solution is the primary factor controlling the occurrence of DHC and consistent with the postulation that the stress induced chemical potential is the driving force for DHC.

  20. Zirconium(IV) dilanthanum(III) penta­sulfide

    PubMed Central

    Raw, Adam D.; Ibers, James A.

    2011-01-01

    Zirconium(IV) dilanthanum(III) penta­sulfide, ZrLa2S5, crystallizes with four formula units in the space group Pnma in the U3S5 structure type. The asymmetric unit comprises one Zr, one La and four S atoms. The Zr and three S atoms are situated on mirror planes. The structure consists of LaS8 face-sharing bicapped distorted trigonal prisms and ZrS7 edge-sharing monocapped octa­hedra. PMID:22199468

  1. Mechanical Properties of Continuous Fiber Reinforced Zirconium Diboride Matrix Composites

    NASA Technical Reports Server (NTRS)

    Stuffle, Kevin; Creegan, Peter; Nowell, Steven; Bull, Jeffrey D.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    Continuous fiber reinforced zirconium diboride matrix composites, SCS-9a-(RBSiCZrB2)matrix, are being developed for leading edge, rocket nozzle and turbine engine applications. Recently, the composite materials have been characterized for tensile properties to 1250 C, the highest temperature tested. The tensile properties are fiber dominated as the matrix is microcracked on fabrication, but favorable failure characteristic are observed. Compression and shear mechanical testing results will be reported if completed. The effects of fiber volume fraction and matrix density on mechanical properties will be discussed. The target applications of the materials will be discussed. Specific testing being performed towards qualification for these applications will be included.

  2. Modeling nitrate removal in a denitrification bed.

    PubMed

    Ghane, Ehsan; Fausey, Norman R; Brown, Larry C

    2015-03-15

    Denitrification beds are promoted to reduce nitrate load in agricultural subsurface drainage water to alleviate the adverse environmental effects associated with nitrate pollution of surface water. In this system, drainage water flows through a trench filled with a carbon media where nitrate is transformed into nitrogen gas under anaerobic conditions. The main objectives of this study were to model a denitrification bed treating drainage water and evaluate its adverse greenhouse gas emissions. Field experiments were conducted at an existing denitrification bed. Evaluations showed very low greenhouse gas emissions (mean N2O emission of 0.12?gNm(-2)min(-1)) from the denitrification bed surface. Field experiments indicated that nitrate removal rate was described by Michaelis-Menten kinetics with the Michaelis-Menten constant of 7.2mgNL(-1). We developed a novel denitrification bed model based on the governing equations for water flow and nitrate removal kinetics. The model evaluation statistics showed satisfactory prediction of bed outflow nitrate concentration during subsurface drainage flow. The model can be used to design denitrification beds with efficient nitrate removal which in turn leads to enhanced drainage water quality. PMID:25638338

  3. Microbial Uranium Immobilization Independent of Nitrate Reduction

    SciTech Connect

    Madden, Andrew; Smith, April; Balkwill, Dr. David; Fagan, Lisa Anne; Phelps, Tommy Joe

    2007-01-01

    At many uranium processing and handling facilities, including sites in the U.S. Department of Energy (DOE) complex, high levels of nitrate are present as co-contamination with uranium in groundwater. The daunting prospect of complete nitrate removal prior to the reduction of uranium provides a strong incentive to explore bioremediation strategies that allow for uranium bioreduction and stabilization in the presence of nitrate. Typical in-situ strategies involving the stimulation of metal-reducing bacteria are hindered by low pH environments at this study site and require that the persistent nitrate must first and continuously be removed or transformed prior to uranium being a preferred electron acceptor. This project investigates the possibility of stimulating nitrate-indifferent, pH-tolerant microorganisms to achieve bioreduction of U(VI) despite nitrate persistence. Successful enrichments from U-contaminated sediments demonstrated nearly complete reduction of uranium with very little loss of nitrate from pH 4.9-5.6 using methanol or glycerol as a carbon source. Higher pH enrichments also demonstrated similar U reduction capacity with 5-30% nitrate loss within one week. Bacterial 16S rRNA genes were amplified from uranium-reducing enrichments (pH 5.7-6.7) and sequenced. Phylogenetic analyses classified the clone sequences into four distinct clusters. Data from sequencing and T-RFLP profiles indicated that the majority of the microorganisms stimulated by these enrichment conditions consisted of low G+C Gram-positive bacteria most closely related to Clostridium and Clostridium-like organisms. This research demonstrates that the stimulation of a natural microbial community to immobilize U through bioreduction is possible without the removal of nitrate.

  4. Photodegradation of Paracetamol in Nitrate Solution

    SciTech Connect

    Meng Cui; Qu Ruijuan; Liang Jinyan; Yang Xi

    2010-11-24

    The photodegradation of paracetamol in nitrate solution under simulated solar irradiation has been investigated. The degradation rates were compared by varying environmental parameters including concentrations of nitrate ion, humic substance and pH values. The quantifications of paracetamol were conducted by HPLC method. The results demonstrate that the photodegradation of paracetamol followed first-order kinetics. The photoproducts and intermediates of paracetamol in the presence of nitrate ions were identified by extensive GC-MS method. The photodegradation pathways involving. OH radicals as reactive species were proposed.

  5. Photodegradation of Paracetamol in Nitrate Solution

    NASA Astrophysics Data System (ADS)

    Meng, Cui; Qu, Ruijuan; Liang, Jinyan; Yang, Xi

    2010-11-01

    The photodegradation of paracetamol in nitrate solution under simulated solar irradiation has been investigated. The degradation rates were compared by varying environmental parameters including concentrations of nitrate ion, humic substance and pH values. The quantifications of paracetamol were conducted by HPLC method. The results demonstrate that the photodegradation of paracetamol followed first-order kinetics. The photoproducts and intermediates of paracetamol in the presence of nitrate ions were identified by extensive GC-MS method. The photodegradation pathways involving. OH radicals as reactive species were proposed.

  6. Nitrate dry deposition measurements with surrogate surfaces

    NASA Astrophysics Data System (ADS)

    Zhu, Xiang

    Nitrate dry deposition is one of the most important topics in the study of the dry deposition of acidic and acidifying substances. This study measured nitrate dry deposition to (1) a water surface sampler (WSS) which was recently developed in the Department of Chemical and Environmental Engineering at Illinois Institute of Technology, (2) a Nylasorb filter on a knife-edge surrogate surface and (3) a greased strip on a knife-edge surrogate surface. Airborne nitric acid (HNO3), nitrous acid (HNO2), and nitrogen dioxide (NO2) concentrations were also measured concurrently with the flux measurements. These measurements were then used to evaluate the utility of using surrogate surfaces, and in particular the WSS, to measure nitrate dry deposition. The nitrogen containing species that may be responsible for nitrate dry deposition to the WSS include nitrogen monoxide (NO), NO2, peroxyacetyl nitrate (PAN), ammonia (NH3) and ammonium (NH4+), HNO2,/ HNO3, and particulate nitrate. Theoretical calculations and experiments showed that HNO3 and particulate nitrate appear to be the major nitrate contributors to the water surface sampler. Nitrate dry deposition to the water surface, Nylasorb filter and the greased strip were measured during the daytime in June and July 1995 and during both the day and night time in September and October 1995. The results showed that during the daytime in June and July the average nitrate dry deposition to the WSS (36.28 mg/m2-day) was much higher than that to the Nylasorb filter (14.04 mg/m2-day). However, during September and October there is no statistically significant difference in nitrate deposition flux between the WSS (average 4.59 mg/m2-day for the nighttime and 10.58 mg/m2-day for the daytime) and the Nylasorb filter (average 4.53 mg/m2-day for the nighttime and 8.87 mg/m2-day). A set of three experiments showed that particulate nitrate fluxes measured with the greased strip were underestimated due to the loss of volatile particulate nitrate. These experiments included a comparison of nitrate fluxes from greased strip samples extracted immediately after sampling and extracted later, a heating experiment with the greased strip samples, and a comparison between short-term and long-term greased strip samples. After precautions were taken to prevent particulate nitrate loss during sampling, a new set of samples was taken in November of 1996. The results showed that there is no statistically significant difference between the mass transfer coefficient of HNO3 (average 1.68 cm/sec) and that of sulfur dioxide (SO2) (average 1.41 cm/sec) as expected from theory. The mass transfer coefficient of HNO3 was obtained by dividing HNO3 flux (obtained by subtracting the particulate nitrate flux measured with greased strip from total nitrate flux measured with the WSS) by HNO3 concentration.

  7. Kinetics of formation of a platelet-reinforced ceramic composite prepared by the directed reaction of zirconium with boron carbide

    SciTech Connect

    Johnson, W.B.; Nagelberg, A.S.; Breval, E. )

    1991-09-01

    In this paper the kinetics of formation of a new class of ceramic composite material, zirconium diboride platelet-reinforced zirconium carbides, are discussed. These materials are prepared by the directed reaction of molten zirconium with boron carbide to form a ceramic material composed of zirconium diboride platelets approximately uniformly distributed in a zirconium carbide matrix containing a controlled amount of residual zirconium metal. Results from interrupted growth studies, differential thermal analysis, adiabatic reaction temperature calculations, and kinetic measurements have been used to study the kinetics of the process. The reaction is very fast and proceeds parabolically with time with a rate constant between 1.6 {times} 10{sup {minus}2} and 3.9 {times} 10{sup {minus}2} cm{sup 2}/s. The proposed mechanism suggests that when molten zirconium contacts boron carbide, the molten zirconium exothermically reacts with the boron carbide to form a boron-rick liquid. Further reaction is sustained by the continuous dissolution of the boron carbide as the boron-rich liquid is drawn into the boron carbide. The product is a zirconium diboride/zirconium carbide/zirconium composite which homogenizes quickly at the reaction temperature to yield a uniform product microstructure throughout the composite. Two alternative rate-limiting steps are discussed and the implications of each are explored.

  8. Solidification of a Vacuum Arc-Remelted Zirconium Ingot

    NASA Astrophysics Data System (ADS)

    Revil-Baudard, Matthieu; Jardy, Alain; Combeau, Hervé; Leclerc, Faustine; Rebeyrolle, Véronique

    2013-10-01

    As the quality of vacuum arc-remelted (VAR) zirconium ingots is directly linked to their chemical homogeneity and their metallurgical structure after solidification, it is important to predictively relate these factors to the operating conditions. Therefore, a detailed modeling study of the solidification process during VAR has been undertaken. To this purpose, the numerical macromodel SOLAR has been used. Assuming axisymmetrical geometry, this model is based on the solution of the coupled transient heat, momentum, and solute transport equations, under turbulent flow conditions during the remelting, hot-topping, and cooling of a cylindrical ingot. The actual operating parameters are defined as inputs for the model. Each of them, mainly the melting current sequence, melting rate sequence, and stirring parameters (current and period), is allowed to vary with time. Solidification mechanisms recently implemented in the model include a full coupling between energy and solute transport in the mushy zone. This modeling can be applied to actual multicomponent alloys. In this article, the macrosegregation induced by solidification in a zirconium alloy ingot is investigated. In order to validate the model results, a full-scale homogeneous Zy4 electrode has been remelted, and the resulted ingot has been analyzed. The model results show a general good agreement with the chemistry analyses, as soon as thermosolutal convection is accounted for to simulate accurately the interdendritic fluid flow in the central part of the ingot.

  9. Nucleation and growth kinetics of zirconium-oxo-alkoxy nanoparticles.

    PubMed

    Labidi, Sana; Jia, Zixian; Amar, Mounir Ben; Chhor, Khay; Kanaev, Andrei

    2015-01-28

    Nucleation and growth of zirconium-oxo-alkoxy (ZOA) nanoparticles were studied in a sol-gel process in n-propanol solution at a hydrolysis ratio H between 1.0 and 2.7 and zirconium-n-propoxyde precursor concentrations between 0.10 and 0.15 mol l(-1). The chemical transformations were conducted in quasi-perfect micromixing conditions (Damköhler number Da ≤ 1) and the nanoparticle size evolution was monitored in situ with the light scattering method. The size of primary nanoparticles (nuclei) 2R0 = 3.6 nm was found to be almost independent of the preparation conditions. A remarkable similarity with the titanium-oxo-alkoxy (TOA) nanoparticles was observed. In particular, both systems show the induction stage of the sol-gel growth for a hydrolysis ratio H > 2.0 and stable oxometallate units for H≤ 2.0. However in contrast to TOA, no stable hierarchical ZOA units (clusters) with R0≥R≥ 1.0 nm were observed, which makes this system less stable against aggregation, leading to polydispersed nanoparticles. PMID:25502510

  10. Dispersion type zirconium matrix fuels fabricated by capillary impregnation method

    NASA Astrophysics Data System (ADS)

    Savchenko, A.; Konovalov, I.; Vatulin, A.; Morozov, A.; Orlov, V.; Uferov, O.; Ershov, S.; Laushkin, A.; Kulakov, G.; Maranchak, S.; Petrova, Z.

    2007-05-01

    Several novel dispersion fuel compositions with a high uranium content fuel (U9Mo, U5Zr5Nb, U3Si) and a zirconium alloy matrix with low melting point (1063-1133 K) have been developed at A.A. Bochvar Institute using a capillary impregnation fabrication method. The capillary impregnation method introduces fuel granules and granules of a zirconium alloy into a fuel element followed by a short-term anneal at a temperature above the melting temperature of alloy. The alloy melts down and under capillary forces moves into the joints between the fuel element components to form metallurgical bonds. The volume ratios between the components are: 55-65% fuel, 10-20% matrix, and 15-30% pores. Fuel elements produced by capillary impregnation method have a high uranium content (9-10 g cm-3) and a high thermal conductivity (18-22 W m-1 K-1), which, when used as PWR or BWR fuels allow the fuel temperature to be lowered to 723-773 K. They also feature porosity to accommodate swelling. The metallurgical fuel-cladding bond makes the fuel elements serviceable in power transients. The primary advantages for PWR, BWR and CANDU use of these fuels elements, would be the high uranium content, low fuel temperature and serviceability under transient conditions. Consideration is given to their applicability in Floating Nuclear Power Plants (FNPP) as well as for the feasibility of burning civil and weapon grade plutonium.

  11. Cluster Dynamics modelling of irradiation growth of zirconium single crystals

    NASA Astrophysics Data System (ADS)

    Christien, F.; Barbu, A.

    2009-08-01

    This paper aims at modelling irradiation growth of zirconium single crystals as a function of neutron fluence. The Cluster Dynamics approach is used, which makes it possible to describe the variation of irradiation microstructure (dislocation loops) with neutron fluence. From the irradiation microstructure, the strain can be calculated along the axes of the lattice structure. The model is applied to the growth of annealed zirconium single crystals at 553 K measured by Carpenter and Rogerson in 1981 and 1987. The model is found to fit the experimentally measured growth of Zr single crystals very nicely, even at large neutron fluence where the 'breakaway growth' occurs. This was made possible by considering in the model the growth of vacancy loops in the basal planes. This growth of vacancy loops in the basal planes could be modelled by taking into account that diffusion of self-interstitial atoms (SIA) is anisotropic and that there exist in the basal planes some nucleation sites for vacancy loops (iron clusters), the density of which is considered constant over time.

  12. Wear Analysis in THA Utilizing Oxidized Zirconium and Crosslinked Polyethylene

    PubMed Central

    Garvin, Kevin L.; Mangla, Jimmi; Murdoch, Nathan; Martell, John M.

    2008-01-01

    Oxidized zirconium, a material with a ceramic surface on a metal substrate, and highly cross-linked polyethylene are two materials developed to reduce wear. We measured in vivo femoral head penetration in patients with these advanced bearings. We hypothesized the linear wear rates would be lower than those published for cobalt-chrome and standard polyethylene. We retrospectively reviewed a select series of 56 THAs in a relatively young, active patient population utilizing oxidized zirconium femoral heads and highly cross-linked polyethylene acetabular liners. Femoral head penetration was determined using the Martell computerized edge-detection method. All patients were available for 2-year clinical and radiographic followup. True linear wear was 4 μm/year (95% confidence intervals, ± 59 μm/year). The early wear rates in this cohort of relatively young, active patients were low and we believe justify the continued study of these alternative bearing surfaces. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18946711

  13. Phase diagram of ammonium nitrate

    SciTech Connect

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2013-12-07

    Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO–AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N{sub 2}, N{sub 2}O, and H{sub 2}O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV{sup ′} transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

  14. Evaluation of the resistance of irradiated zirconium-liner cladding to iodine-induced stress corrosion cracking

    NASA Astrophysics Data System (ADS)

    Shimada, Sachio; Nagai, Masayuki

    1983-02-01

    An evaluation was made of irradiated zirconium-liner cladding for its resistance to iodine-induced stress corrosion cracking (SCC). Emphasis was put on irradiation-induced hardening in zirconium and SCC resistance in zirconium-liner cladding as compared with Zircaloy-2 cladding. The Vickers microhardness test revealed that crystal bar zirconium experienced less hardening than Zircaloy-2 during neutron exposure. The SCC resistance of zirconium-liner cladding was evaluated for failure strains under the tube pressurization SCC test, and compared with the results of Zircaloy-2 cladding. The failure strains of zirconium-liner cladding were significantly larger than those of Zircaloy-2 cladding over all neutron fluence ranges examined, e.g., more than ten times at 1.0 × 10 21n/ cm2 ( E > 1 MeV). Judging from our results on the Vickers microhardness and SCC tests, good SCC resistance of zirconium-liner cladding could be expected even at high fluences.

  15. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

    PubMed Central

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-01-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution. PMID:26980545

  16. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions.

    PubMed

    Nayak, Nadiya B; Nayak, Bibhuti B

    2016-01-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution. PMID:26980545

  17. Aqueous sodium borohydride induced thermally stable porous zirconium oxide for quick removal of lead ions

    NASA Astrophysics Data System (ADS)

    Nayak, Nadiya B.; Nayak, Bibhuti B.

    2016-03-01

    Aqueous sodium borohydride (NaBH4) is well known for its reducing property and well-established for the development of metal nanoparticles through reduction method. In contrary, this research paper discloses the importance of aqueous NaBH4 as a precipitating agent towards development of porous zirconium oxide. The boron species present in aqueous NaBH4 play an active role during gelation as well as phase separated out in the form of boron complex during precipitation, which helps to form boron free zirconium hydroxide [Zr(OH)4] in the as-synthesized condition. Evolved in-situ hydrogen (H2) gas-bubbles also play an important role to develop as-synthesized loose zirconium hydroxide and the presence of intra-particle voids in the loose zirconium hydroxide help to develop porous zirconium oxide during calcination process. Without any surface modification, this porous zirconium oxide quickly adsorbs almost hundred percentages of toxic lead ions from water solution within 15 minutes at normal pH condition. Adsorption kinetic models suggest that the adsorption process was surface reaction controlled chemisorption. Quick adsorption was governed by surface diffusion process and the adsorption kinetic was limited by pore diffusion. Five cycles of adsorption-desorption result suggests that the porous zirconium oxide can be reused efficiently for removal of Pb (II) ions from aqueous solution.

  18. Cobalt cluster effects in zirconium promoted Co/SiO{sub 2} Fischer-Tropsch catalysts

    SciTech Connect

    Feller, A.; Claeys, M.; Steen, E. van

    1999-07-01

    The effect of zirconium addition to the catalyst formulation of Co/SiO{sub 2} Fischer-Tropsch catalysts was investigated. With increasing zirconium content the strong interaction between silica and cobalt is reduced and a somewhat weaker cobalt-zirconium interaction is observed. Therefore the degree of reduction of catalysts, which were reduced at 400 C for 16 h, increases strongly. The cobalt crystallite size increases with increasing zirconium content, leading to smaller cobalt metal surface areas for the freshly reduced catalyst. Cobalt particles can be found in clusters on the silica support. The size of cobalt clusters decreases and thus the number of cobalt particles within a cluster decreases with increasing zirconium content. At steady-state conditions the CO-conversion of the promoted catalyst in the Fischer-Tropsch synthesis increases with increasing zirconium content. The C{sub 5+}-selectivity and the secondary hydrogenation activity pass a maximum with increasing zirconium content. The observed changes in activity and selectivity are explained in terms of an increase in the amount of metallic cobalt available under reaction conditions, leading to an increased activity, and a decrease in the cobalt cluster size, which diminishes the probability for secondary reactions. Furthermore, it was concluded that secondary double bond isomerization can be catalyzed to some extent by zirconia.

  19. Layered zirconium phosphonate with inorganic-organic hybrid structure: Preparation and its assembly with DNA

    NASA Astrophysics Data System (ADS)

    Liu, Li-Min; Lu, Guo-Yuan; Jiang, Li-Ping; Zhu, Jun-Jie

    2014-07-01

    An aminoethoxy-functionalized zirconium phosphonate (Zr(O3POCH2CH2NH2)2·3H2O), abbreviated as ZrRP (R=OCH2CH2NH2), with layered structure has been synthesized. This layered compound possesses the characteristic of inorganic-organic hybrid, due to the covalently linked aminoethoxy in the host layer. The anion exchanged property of this zirconium phosphonate is suitable for the direct intercalation of negatively charged DNA, which is different from these reported zirconium phosphates or zirconium phosphonates. As a precursor, this prepared zirconium phosphonate was utilized to fabricate a novel DNA/ZrRP binary hybrid via a delamination-reassembly procedure. The release behavior of DNA from the DNA/ZrRP composite was investigated at different medium pH, because the combination between zirconium phosphonate sheets and DNA was pH-dependent sensitively. Moreover, the helical conformation of DNA was almost retained after the intercalation and release process. These properties of the DNA/ZrRP composite suggested the potential application of layered zirconium phosphonate as a non-viral vector in gene delivery.

  20. Qualitative Determination of Nitrate with Triphenylbenzylphosphonium Chloride.

    ERIC Educational Resources Information Center

    Berry, Donna A.; Cole, Jerry J.

    1984-01-01

    Discusses two procedures for the identification of nitrate, the standard test ("Brown Ring" test) and a new procedure using triphenylbenzylphosphonium chloride (TPBPC). Effectiveness of both procedures is compared, with the TPBPC test proving to be more sensitive and accurate. (JM)

  1. Does thiosemicarbazide lead nitrate crystal exist?

    NASA Astrophysics Data System (ADS)

    Fernandes, Royle; Srinivasan, Bikshandarkoil R.

    2016-06-01

    The authors of a recent paper (Optik 125 (2014) 2022-2025) claim to have grown a so called thiosemicarbazide lead nitrate (TSLN) crystal by the slow evaporation method. In this comment we prove that TSLN is actually thiosemicarbazide.

  2. Microbial uranium immobilization independent of nitrate reduction.

    PubMed

    Madden, Andrew S; Smith, April C; Balkwill, David L; Fagan, Lisa A; Phelps, Tommy J

    2007-09-01

    At many uranium processing and handling facilities, including sites in the US Department of Energy (DOE) complex, high levels of nitrate are present as co-contamination with uranium in groundwater. The daunting prospect of complete nitrate removal prior to the reduction of uranium provides a strong incentive to explore bioremediation strategies that allow for uranium bioreduction and stabilization in the presence of nitrate. Typical in situ strategies involving the stimulation of metal-reducing bacteria are hindered by low-pH environments and require that the persistent nitrate must first and continuously be removed or transformed prior to uranium being a preferred electron acceptor. This work investigated the possibility of stimulating nitrate-indifferent, pH-tolerant microorganisms to achieve bioreduction of U(VI) despite nitrate persistence. Enrichments from U-contaminated sediments demonstrated nearly complete reduction of uranium with very little loss of nitrate from pH 5.7-6.2 using methanol or glycerol as a carbon source. Bacterial 16S rRNA genes were amplified from uranium-reducing enrichments (pH 5.7-6.2) and sequenced. Phylogenetic analyses classified the clone sequences into four distinct clusters. Data from sequencing and terminal-restriction fragment length polymorphism (T-RFLP) profiles indicated that the majority of the microorganisms stimulated by these enrichment conditions consisted of low G+C Gram-positive bacteria most closely related to Clostridium and Clostridium-like organisms. This research demonstrates that the stimulation of a natural microbial community to immobilize U through bioreduction is possible without the removal of nitrate. PMID:17686028

  3. Is beetroot juice more effective than sodium nitrate? The effects of equimolar nitrate dosages of nitrate-rich beetroot juice and sodium nitrate on oxygen consumption during exercise.

    PubMed

    Flueck, Joelle Leonie; Bogdanova, Anna; Mettler, Samuel; Perret, Claudio

    2016-04-01

    Dietary nitrate has been reported to lower oxygen consumption in moderate- and severe-intensity exercise. To date, it is unproven that sodium nitrate (NaNO3(-); NIT) and nitrate-rich beetroot juice (BR) have the same effects on oxygen consumption, blood pressure, and plasma nitrate and nitrite concentrations or not. The aim of this study was to compare the effects of different dosages of NIT and BR on oxygen consumption in male athletes. Twelve healthy, well-trained men (median [minimum; maximum]; peak oxygen consumption: 59.4 mL·min(-1)·kg(-1) [40.5; 67.0]) performed 7 trials on different days, ingesting different nitrate dosages and placebo (PLC). Dosages were 3, 6, and 12 mmol nitrate as concentrated BR or NIT dissolved in plain water. Plasma nitrate and nitrite concentrations were measured before, 3 h after ingestion, and postexercise. Participants cycled for 5 min at moderate intensity and further 8 min at severe intensity. End-exercise oxygen consumption at moderate intensity was not significantly different between the 7 trials (p = 0.08). At severe-intensity exercise, end-exercise oxygen consumption was ∼4% lower in the 6-mmol BR trial compared with the 6-mmol NIT (p = 0.003) trial as well as compared with PLC (p = 0.010). Plasma nitrite and nitrate concentrations were significantly increased after the ingestion of BR and NIT with the highest concentrations in the 12-mmol trials. Plasma nitrite concentration between NIT and BR did not significantly differ in the 6-mmol (p = 0.27) and in the 12-mmol (p = 0.75) trials. In conclusion, BR might reduce oxygen consumption to a greater extent compared with NIT. PMID:26988767

  4. Synthesis of a new energetic nitrate ester

    SciTech Connect

    Chavez, David E

    2008-01-01

    Nitrate esters have been known as useful energetic materials since the discovery of nitroglycerin by Ascanio Sobrero in 1846. The development of methods to increase the safety and utility of nitroglycerin by Alfred Nobel led to the revolutionary improvement in the utility of nitroglycerin in explosive applications in the form of dynamite. Since then, many nitrate esters have been prepared and incorporated into military applications such as double-based propellants, detonators and as energetic plasticizers. Nitrate esters have also been shown to have vasodilatory effects in humans and thus have been studied and used for treatments of ailments such as angina. The mechanism of the biological response towards nitrate esters has been elucidated recently. Interestingly, many of the nitrate esters used for military purposes are liquids (ethylene glycol dinitrate, propylene glycol dinitrate, etc). Pentaerythritol tetranitrate (PETN) is one of the only solid nitrate esters, besides nitrocellulose, that is used in any application. Unfortunately, PETN melting point is above 100 {sup o}C, and thus must be pressed as a solid for detonator applications. A more practical material would be a melt-castable explosive, for potential simplification of manufacturing processes. Herein we describe the synthesis of a new energetic nitrate ester (1) that is a solid at ambient temperatures, has a melting point of 85-86 {sup o}C and has the highest density of any known nitrate ester composed only of carbon, hydrogen, nitrogen and oxygen. We also describe the chemical, thermal and sensitivity properties of 1 as well as some preliminary explosive performance data.

  5. The UK Nitrate Time Bomb (Invited)

    NASA Astrophysics Data System (ADS)

    Ward, R.; Wang, L.; Stuart, M.; Bloomfield, J.; Gooddy, D.; Lewis, M.; McKenzie, A.

    2013-12-01

    The developed world has benefitted enormously from the intensification of agriculture and the increased availability and use of synthetic fertilizers during the last century. However there has also been unintended adverse impact on the natural environment (water and ecosystems) with nitrate the most significant cause of water pollution and ecosystem damage . Many countries have introduced controls on nitrate, e.g. the European Union's Water Framework and Nitrate Directives, but despite this are continuing to see a serious decline in water quality. The purpose of our research is to investigate and quantify the importance of the unsaturated (vadose) zone pathway and groundwater in contributing to the decline. Understanding nutrient behaviour in the sub-surface environment and, in particular, the time lag between action and improvement is critical to effective management and remediation of nutrient pollution. A readily-transferable process-based model has been used to predict temporal loading of nitrate at the water table across the UK. A time-varying nitrate input function has been developed based on nitrate usage since 1925. Depth to the water table has been calculated from groundwater levels based on regional-scale observations in-filled by interpolated river base levels and vertical unsaturated zone velocities estimated from hydrogeological properties and mapping. The model has been validated using the results of more than 300 unsaturated zone nitrate profiles. Results show that for about 60% of the Chalk - the principal aquifer in the UK - peak nitrate input has yet to reach the water table and concentrations will continue to rise over the next 60 years. The implications are hugely significant especially where environmental objectives must be achieved in much shorter timescales. Current environmental and regulatory management strategies rarely take lag times into account and as a result will be poorly informed, leading to inappropriate controls and conflicts between policy makers, environmentalists and industry.

  6. Protein Nitration in Placenta – Functional Significance

    PubMed Central

    Webster, RP; Roberts, VHJ; Myatt, L

    2009-01-01

    Crucial roles of the placenta are disrupted in early and mid-trimester pregnancy loss, preeclampsia, eclampsia and intrauterine growth restriction. The pathophysiology of these disorders includes a relative hypoxia of the placenta, ischemia/reperfusion injury, an inflammatory response and oxidative stress. Reactive oxygen species including nitric oxide (NO), carbon monoxide and superoxide have been shown to participate in trophoblast invasion, regulation of placental vascular reactivity and other events. Superoxide, which regulates expression of redox sensitive genes, has been implicated in up-regulation of transcription factors, antioxidant production, angiogenesis, proliferation and matrix remodeling. When superoxide and nitric oxide are present in abundance, their interaction yields peroxynitrite a potent pro-oxidant, but also alters levels of nitric oxide, which in turn affect physiological functions. The peroxynitrite anion is extremely unstable thus evidence of its formation in vivo has been indirect via the occurrence of nitrated moieties including nitrated lipids and nitrotyrosine residues in proteins. Formation of 3-nitrotyrosine (protein nitration) is a “molecular fingerprint” of peroxynitrite formation. Protein nitration has been widely reported in a number of pathological states associated with inflammation but is reported to occur in normal physiology and is thought of as a prevalent, functionally relevant post-translational modification of proteins. Nitration of proteins can give either no effect, a gain or a loss of function. Nitration of a range of placental proteins is found in normal pregnancy but increased in pathologic pregnancies. Evidence is presented for nitration of placental signal transduction enzymes and transporters. The targets and extent of nitration of enzymes, receptors, transporters and structural proteins may markedly influence placental cellular function in both physiologic and pathologic settings. PMID:18851882

  7. A search for nitrates in Martian meteorites

    NASA Astrophysics Data System (ADS)

    Grady, Monica M.; Wright, I. P.; Pillinger, C. T.

    1995-03-01

    Martian atmospheric nitrogen is highly enriched in N-15; nitrates formed by interaction of the atmosphere with the Martian regolith should therefore also be characterized by an elevated delta N-15 value. A search has been made for nitrates in two Martian meteorites, in order to determine the extent of possible regolith-atmosphere interaction. Shock-produced glass from the Elephant Moraine (EET) A79001 shergottite (E1,149) and a water-soluble extract from Nakhla were analyzed by Fourier transform infrared (FTIR) spectroscopy and stepped combustion-stable isotope mass spectrometry. FTIR of both meteorites had features at 1375/cm and 1630/cm, consistent with nitrates. On account of their low thermal stability, nitrates break down at temperatures below 600 C; in this temperature range, E1,149 yeilded approximately 1250 ppb nitrogen with delta N-15 -8 +/- 5%. If this nitrogen is from a nitrate, then it cannot be distinquished from terrestial salts by its isotopic composition. The water-soluble extract from Nakhla also released nitrogen at low temperatures, approximately 17 ppb with delta N-15 approximately -11 +/- 4%. Since Nakhla is an observed 'fall', this is unlikely to be a terrestial weathering product. Nitrates apparently occur in E1,149 and Nakhla, but in very low abundance, and their origin is unclear. The isotopic composition of the salts, which is within the range of that proposed for Martian magmatic volatiles, is far removed from that of nitrogen in the present-day Martian atmosphere. If the nitrates are Martian in origin, they did not form in recent times from reactions involving atmospheric gases. Rather, the nitrates could be the result of an earlier episode of atmospheric interaction with the regolith, or with implantation of magmatic volatiles introduced during degassing.

  8. Comparison of corrosion behavior of zirconium bombarded with self-ion and molybdenum ion

    SciTech Connect

    Peng, D.Q.; Bai, X.D.; Chen, X.W.; Zhou, Q.G.; Liu, X.Y.; Yu, R.H.; Deng, P.Y

    2004-08-03

    In order to study the effects of zirconium and molybdenum ion bombardment on the aqueous corrosion behavior of zirconium, one group of specimens was implanted with zirconium ions with ions surface densities ranging from 1 x 10{sup 15} to 2 x 10{sup 17} ions/cm{sup 2} at about 170 deg. C, using a metal vapor vacuum arc (MEVVA) source operated at an extraction voltage of 50 kV. The other group of specimens was bombarded with molybdenum ion with ions surface densities ranging from 1 x 10{sup 16} to 5 x 10{sup 17} ions/cm{sup 2} at about 160 deg. C, using a MEVVA source operated at an extraction voltage of 40 kV. The valence states and depth distribution of elements in the surface of the samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. Polarization curves measurement was employed to evaluate the aqueous corrosion resistance of the zirconium samples in a 1N H{sub 2}SO{sub 4} solution. It was found that the aqueous corrosion resistance of zirconium implanted with 5 x 10{sup 16} Zr ions/cm{sup 2} is the best in first group samples. For molybdenum ion implantation, the aqueous corrosion resistance of samples declined with raising ions surface densities. The natural corrosion potentials of zirconium samples bombarded with self-ions are more negative than that of the as-received zirconium. While, as for molybdenum ion implantation, the results are opposite. Finally, the mechanisms of the corrosion behavior of the zirconium samples implanted with zirconium and molybdenum ions are discussed.

  9. Nitrate inhibition of legume nodule growth and activity. II. Short term studies with high nitrate supply

    SciTech Connect

    Streeter, J.G.

    1985-02-01

    Soybean plants (Glycine max (L.) Merr) were grown in sand culture with 2 millimolar nitrate for 37 days and then supplied with 15 millimolar nitrate for 7 days. Control plants received 2 millimolar nitrate and 13 millimolar chloride and, after the 7-day treatment period, all plants were supplied with nil nitrate. The temporary treatment with high nitrate inhibited nitrogenase (acetylene reduction) activity by 80% whether or not Rhizobium japonicum bacteroids had nitrate reductase (NR) activity. The pattern of nitrite accumulation in nodules formed by NR/sup +/ rhizobia was inversely related to the decrease and recovery of nitrogenase activity. However, nitrite concentration in nodules formed by NR/sup -/ rhizobia appeared to be too low to explain the inhibition of nitrogenase. Nodules on plants treated with 15 millimolar nitrate contained higher concentrations of amino N and, especially, ureide N than control nodules and, after withdrawal of nitrate, reduced N content of treated and control nodules returned to similar levels. The accumulation of N/sub 2/ fixation products in nodules in response to high nitrate treatment was observed with three R. japonicum strains, two NR/sup +/ and one NR/sup -/.

  10. Specific electrochemical nitration of horse heart myoglobin.

    PubMed

    Kendall, G; Cooper, H J; Heptinstall, J; Derrick, P J; Walton, D J; Peterson, I R

    2001-08-15

    Earlier findings on electronitration of hen egg-white lysozyme demonstrated a product which was mononitrated at Tyr23, by ion-exchange chromatography, absorbance at 430 nm, dithionite reduction, and Edman sequencing of a nitrated proteolytic peptide. However, the whole protein was not sequenced; therefore, although the enzyme remained active upon nitration, reaction at other residues could not be completely eliminated. This study has now been extended to the redox protein myoglobin. We demonstrate the novel electronitration (electrooxidation in the presence of nitrite) of a specific tyrosine residue in horse heart myoglobin and also in apomyoglobin. Production of the yellow chromophore, 3-nitrotyrosine (3-NT), was apparent in apomyoglobin from A430 but was masked in holomyoglobin by the Soret band. In both cases, the presence of 3-NT in the electronitrated samples was further indicated by the binding of antibody to 3-NT in Western blots. High-resolution electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FTICR) mass spectrometry revealed a reaction product at [M + 45] (consistent with substitution of NO2 for H), indicating that the nitration reaction is the only reaction occurring which gives rise to a change in mass in the electrooxidation. Fragmentation mass spectrometry identified the nitration site as Tyr103, with no nitration at Tyr146. The procedure may be useful in preparing model nitrated proteins for the study of disease mechanisms. PMID:11488590

  11. [Photodegradation of atenolol in aqueous nitrate solution].

    PubMed

    Ji, Yue-Fei; Zeng, Chao; Meng, Cui; Yang, Xi; Gao, Shi-Xiang

    2012-02-01

    The aqueous photolysis of beta-blocker atenolol (ATL) using Xe lamp as simulated solar irradiation source was investigated in the presence of nitrate ions. The effects of nitrate ion concentration, solution pH value, and concentration of bicarbonate and humic substance on the photodegradation of ATL were studied. The results showed that photodegradation of ATL in nitrate solution followed pseudo-first-order kinetics. The increasing concentration of nitrate ion promoted the photodegradation rate of ATL. The first-order rate constant increased from 0.002 26 min(-1) to 0.009 4 min(-1) with nitrate concentration increasing from 0 to 5 mmol x L(-1). Acidic or alkaline condition of the solution favored the photodegradation of ATL. Different concentration of bicarbonate showed insignificant effect of the degradation while the increasing concentration of fulvic acid showed inhibiting effect. Hydroxyl radical was determined to be formed during the photolysis process of ATL using isopropanol as molecular probe. The main photoproducts of ATL were identified by using SPE-LC-MS techniques and possible photoinduced degradation pathways in nitrate solution were proposed. PMID:22509585

  12. Suppression of erythropoiesis by dietary nitrate.

    PubMed

    Ashmore, Tom; Fernandez, Bernadette O; Evans, Colin E; Huang, Yun; Branco-Price, Cristina; Griffin, Julian L; Johnson, Randall S; Feelisch, Martin; Murray, Andrew J

    2015-03-01

    In mammals, hypoxia-triggered erythropoietin release increases red blood cell mass to meet tissue oxygen demands. Using male Wistar rats, we unmask a previously unrecognized regulatory pathway of erythropoiesis involving suppressor control by the NO metabolite and ubiquitous dietary component nitrate. We find that circulating hemoglobin levels are modulated by nitrate at concentrations achievable by dietary intervention under normoxic and hypoxic conditions; a moderate dose of nitrate administered via the drinking water (7 mg NaNO3/kg body weight/d) lowered hemoglobin concentration and hematocrit after 6 d compared with nonsupplemented/NaCl-supplemented controls. The underlying mechanism is suppression of hepatic erythropoietin expression associated with the downregulation of tissue hypoxia markers, suggesting increased pO2. At higher nitrate doses, however, a partial reversal of this effect occurred; this was accompanied by increased renal erythropoietin expression and stabilization of hypoxia-inducible factors, likely brought about by the relative anemia. Thus, hepatic and renal hypoxia-sensing pathways act in concert to modulate hemoglobin in response to nitrate, converging at an optimal minimal hemoglobin concentration appropriate to the environmental/physiologic situation. Suppression of hepatic erythropoietin expression by nitrate may thus act to decrease blood viscosity while matching oxygen supply to demand, whereas renal oxygen sensing could act as a brake, averting a potentially detrimental fall in hematocrit. PMID:25422368

  13. Groundwater nitrate pollution in intensively farmed regions

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-12-01

    Intensified agricultural practices that have developed during the past century have helped improve food security for many people but have also added to nitrate pollution in water supply. Balancing the water needs for agriculture with the need for clean groundwater for drinking requires understanding factors such as the routes by which nitrate enters the water supply and how long nitrate remains in the water. The Thames River catchment provides a good study example because the water quality in the river, which supplies drinking water to millions of people, has been monitored for the past 140 years, and the region has undergone significant agricultural development over the past century. Howden et al. studied nitrate transport from agricultural land to water in the Thames basin using a simple model that considers an estimate of the amount of nitrate that could leach the groundwater based on land use practices along with an algorithm that determines the route nitrate would take to reach surface water or groundwater from agricultural areas.

  14. Compartmental model of nitrate retention in streams

    NASA Astrophysics Data System (ADS)

    Faulkner, B. R.; Campana, M. E.

    2007-02-01

    A compartmental modeling approach is presented to route nitrate retention along a cascade of stream reach sections. A process transfer function is used for transient storage equations with first-order reaction terms to represent nitrate uptake in the free stream and denitrification in the storage regions. In the context of a short-term nitrate injection we define nitrate assimilative capacity as 1 - ?, where the attenuation factor, ?, is the fraction of injected nitrate mass that is flushed past the outlet of stream. Net exchange with groundwater is modeled by allowing free stream discharge to vary from one reach section to the next. A Monte Carlo simulation was used to compare results of the compartmental model with the OTIS numerical model. Out of 350 Monte Carlo simulations of a stream consisting of five reach sections the highest relative percent difference was 15%, most being well below 10%, as determined using moment analysis on breakthrough curves. Moment analysis on published experimental breakthrough curves showed assimilative capacities did not differ from those determined with the compartmental model by more than about 0.035 and were well within the uncertainty due to possible errors in measured stream metrics and net exchange with groundwater. The results show that the compartmental modeling approach, commonly used in analysis of groundwater data, can also be useful in evaluating nitrate retention in streams.

  15. Protein tyrosine nitration in the cell cycle

    SciTech Connect

    Jia, Min; Mateoiu, Claudia; Souchelnytskyi, Serhiy

    2011-09-23

    Highlights: {yields} Enrichment of 3-nitrotyrosine containing proteins from cells synchronized in different phases of the cell cycle. {yields} Identification of 76 tyrosine nitrated proteins that change expression during the cell cycle. {yields} Nineteen identified proteins were previously described as regulators of cell proliferation. -- Abstract: Nitration of tyrosine residues in proteins is associated with cell response to oxidative/nitrosative stress. Tyrosine nitration is relatively low abundant post-translational modification that may affect protein functions. Little is known about the extent of protein tyrosine nitration in cells during progression through the cell cycle. Here we report identification of proteins enriched for tyrosine nitration in cells synchronized in G0/G1, S or G2/M phases of the cell cycle. We identified 27 proteins in cells synchronized in G0/G1 phase, 37 proteins in S phase synchronized cells, and 12 proteins related to G2/M phase. Nineteen of the identified proteins were previously described as regulators of cell proliferation. Thus, our data indicate which tyrosine nitrated proteins may affect regulation of the cell cycle.

  16. Stimulating nitrate removal processes of restored wetlands.

    PubMed

    Ballantine, Kate A; Groffman, Peter M; Lehmann, Johannes; Schneider, Rebecca L

    2014-07-01

    The environmental and health effects caused by nitrate contamination of aquatic systems are a serious problem throughout the world. A strategy proposed to address nitrate pollution is the restoration of wetlands. However, although natural wetlands often remove nitrate via high rates of denitrification, wetlands restored for water quality functions often fall below expectations. This may be in part because key drivers for denitrification, in particular soil carbon, are slow to develop in restored wetlands. We added organic soil amendments that range along a gradient of carbon lability to four newly restored wetlands in western New York to investigate the effect of carbon additions on denitrification and other processes of the nitrogen cycle. Soil carbon increased by 12.67-63.30% with the use of soil amendments (p ≤ 0.0001). Soil nitrate, the carbon to nitrogen ratio, and microbial biomass nitrogen were the most significant predictors of denitrification potential. Denitrification potential, potential net nitrogen nitrification and mineralization, and soil nitrate and ammonium, were highest in topsoil-amended plots, with increases in denitrification potential of 161.27% over control plots. While amendment with topsoil more than doubled several key nitrogen cycling processes, more research is required to determine what type and level of amendment application are most effective for stimulating removal of exogenous nitrate and meeting functional goals within an acceptable time frame. PMID:24915604

  17. Process for decomposing nitrates in aqueous solution

    DOEpatents

    Haas, Paul A.

    1980-01-01

    This invention is a process for decomposing ammonium nitrate and/or selected metal nitrates in an aqueous solution at an elevated temperature and pressure. Where the compound to be decomposed is a metal nitrate (e.g., a nuclear-fuel metal nitrate), a hydroxylated organic reducing agent therefor is provided in the solution. In accordance with the invention, an effective proportion of both nitromethane and nitric acid is incorporated in the solution to accelerate decomposition of the ammonium nitrate and/or selected metal nitrate. As a result, decomposition can be effected at significantly lower temperatures and pressures, permitting the use of system components composed of off-the-shelf materials, such as stainless steel, rather than more costly materials of construction. Preferably, the process is conducted on a continuous basis. Fluid can be automatically vented from the reaction zone as required to maintain the operating temperature at a moderate value--e.g., at a value in the range of from about 130.degree.-200.degree. C.

  18. Ligand exchange chromatography of free amino acids and proteins on porous microparticulate zirconium oxide

    SciTech Connect

    Blackwell, J.A. ); Carr, P.W. )

    1992-01-01

    The Lewis acid sites present on the underlying zirconium oxide particles are responsible for the unusual elution sequence for amino acids on copper loaded, phosphated zirconium oxide supports reported in an earlier study. To more thoroughly examine the effect of these strong Lewis acid sites in this paper. The authors have studied ligand exchange chromatography on copper loaded zirconium oxide particles. It is shown here that carboxylate functional groups on amino acid solutes strongly interact with surface Lewis acid sites. Addition of competing hard Lewis bases to the eluent attenuates these specific interactions. The result is a chromatographic system with high selectivity which is also suitable for ligand exchange chromatography of proteins.

  19. Phase transformation of oxide film in zirconium alloy in high temperature hydrogenated water

    SciTech Connect

    Kim, Taeho; Kim, Jongjin; Choi, Kyoung Joon; Yoo, Seung Chang; Kim, Seung Hyun; Kim, Ji Hyun

    2015-07-23

    The effect of the variation of the dissolved hydrogen concentration on the oxide phase transformation under high-temperature hydrogenated water conditions was investigated using in situ Raman spectroscopy. The Raman spectrum in 50 cm(3)/kg of dissolved hydrogen concentration indicated the formation of monoclinic and tetragonal zirconium oxide at the water-substrate interface. As the dissolved hydrogen concentration decreased to 30 cm(3)/kg, the Raman peaks corresponding to the zirconium oxide phase changed, indicating an oxide phase transformation. And, the results of SEM and TEM analyses were compared with those of in situ analyses obtained for the oxide structure formed on the zirconium alloy.

  20. Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress

    PubMed Central

    2015-01-01

    Abstract Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3′,-5′-monophosphate (cGMP) levels lead to an activation of the cGMP-dependent kinase I, thereby causing the relaxation of the vascular smooth muscle by decreasing intracellular calcium concentrations. The hemodynamic and anti-ischemic effects of organic nitrates are rapidly lost upon long-term (low-dose) administration due to the rapid development of tolerance and endothelial dysfunction, which is in most cases linked to increased intracellular oxidative stress. Enzymatic sources of reactive oxygen species under nitrate therapy include mitochondria, NADPH oxidases, and an uncoupled •NO synthase. Acute high-dose challenges with organic nitrates cause a similar loss of potency (tachyphylaxis), but with distinct pathomechanism. The differences among organic nitrates are highlighted regarding their potency to induce oxidative stress and subsequent tolerance and endothelial dysfunction. We also address pleiotropic effects of organic nitrates, for example, their capacity to stimulate antioxidant pathways like those demonstrated for PETN, all of which may prevent adverse effects in response to long-term therapy. Based on these considerations, we will discuss and present some preclinical data on how the nitrate of the future should be designed. Antioxid. Redox Signal. 23, 899–942. PMID:26261901

  1. Organic Nitrate Therapy, Nitrate Tolerance, and Nitrate-Induced Endothelial Dysfunction: Emphasis on Redox Biology and Oxidative Stress.

    PubMed

    Daiber, Andreas; Münzel, Thomas

    2015-10-10

    Organic nitrates, such as nitroglycerin (GTN), isosorbide-5-mononitrate and isosorbide dinitrate, and pentaerithrityl tetranitrate (PETN), when given acutely, have potent vasodilator effects improving symptoms in patients with acute and chronic congestive heart failure, stable coronary artery disease, acute coronary syndromes, or arterial hypertension. The mechanisms underlying vasodilation include the release of •NO or a related compound in response to intracellular bioactivation (for GTN, the mitochondrial aldehyde dehydrogenase [ALDH-2]) and activation of the enzyme, soluble guanylyl cyclase. Increasing cyclic guanosine-3',-5'-monophosphate (cGMP) levels lead to an activation of the cGMP-dependent kinase I, thereby causing the relaxation of the vascular smooth muscle by decreasing intracellular calcium concentrations. The hemodynamic and anti-ischemic effects of organic nitrates are rapidly lost upon long-term (low-dose) administration due to the rapid development of tolerance and endothelial dysfunction, which is in most cases linked to increased intracellular oxidative stress. Enzymatic sources of reactive oxygen species under nitrate therapy include mitochondria, NADPH oxidases, and an uncoupled •NO synthase. Acute high-dose challenges with organic nitrates cause a similar loss of potency (tachyphylaxis), but with distinct pathomechanism. The differences among organic nitrates are highlighted regarding their potency to induce oxidative stress and subsequent tolerance and endothelial dysfunction. We also address pleiotropic effects of organic nitrates, for example, their capacity to stimulate antioxidant pathways like those demonstrated for PETN, all of which may prevent adverse effects in response to long-term therapy. Based on these considerations, we will discuss and present some preclinical data on how the nitrate of the future should be designed. PMID:26261901

  2. Effect of nano-sized cerium-zirconium oxide solid solution on far-infrared emission properties of tourmaline powders

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Yang, Liqing; Hu, Weijie; Li, Wenlong; Wang, Haojing

    2015-10-01

    Far-infrared functional nanocomposites were prepared by the co-precipitation method using natural tourmaline (XY3Z6Si6O18(BO3)3V3W, where X is Na+, Ca2+, K+, or vacancy; Y is Mg2+, Fe2+, Mn2+, Al3+, Fe3+, Mn3+, Cr3+, Li+, or Ti4+; Z is Al3+, Mg2+, Cr3+, or V3+; V is O2‑, OH‑; and W is O2‑, OH‑, or F‑) powders, ammonium cerium(IV) nitrate and zirconium(IV) nitrate pentahydrate as raw materials. The reference sample, tourmaline modified with ammonium cerium(IV) nitrate alone was also prepared by a similar precipitation route. The results of Fourier transform infrared spectroscopy show that tourmaline modified with Ce and Zr has a better far-infrared emission property than tourmaline modified with Ce alone. Through characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the mechanism for oxygen evolution during the heat process in the two composite materials was systematically studied. The XPS spectra show that Fe3+ ratio inside tourmaline modified with Ce alone can be raised by doping Zr. Moreover, it is showed that there is a higher Ce3+ ratio inside the tourmaline modified with Ce and Zr than tourmaline modified with Ce alone. In addition, XRD results indicate the formation of CeO2 and Ce1‑xZrxO2 crystallites during the heat treatment and further TEM observations show they exist as nanoparticles on the surface of tourmaline powders. Based on these results, we attribute the improved far-infrared emission properties of Ce-Zr doped tourmaline to the enhanced unit cell shrinkage of the tourmaline arisen from much more oxidation of Fe2+ to Fe3+ inside the tourmaline caused by the change in the catalyst redox properties of CeO2 brought about by doping with Zr4+. In all samples, tourmaline modified with 7.14 wt.% Ce and 1.86 wt.% Zr calcined at 800∘C for 5 h has the best far-infrared emission property with the maximum emissivity value of 98%.

  3. Suppression of erythropoiesis by dietary nitrate

    PubMed Central

    Ashmore, Tom; Fernandez, Bernadette O.; Evans, Colin E.; Huang, Yun; Branco-Price, Cristina; Griffin, Julian L.; Johnson, Randall S.; Feelisch, Martin; Murray, Andrew J.

    2015-01-01

    In mammals, hypoxia-triggered erythropoietin release increases red blood cell mass to meet tissue oxygen demands. Using male Wistar rats, we unmask a previously unrecognized regulatory pathway of erythropoiesis involving suppressor control by the NO metabolite and ubiquitous dietary component nitrate. We find that circulating hemoglobin levels are modulated by nitrate at concentrations achievable by dietary intervention under normoxic and hypoxic conditions; a moderate dose of nitrate administered via the drinking water (7 mg NaNO3/kg body weight/d) lowered hemoglobin concentration and hematocrit after 6 d compared with nonsupplemented/NaCl-supplemented controls. The underlying mechanism is suppression of hepatic erythropoietin expression associated with the downregulation of tissue hypoxia markers, suggesting increased pO2. At higher nitrate doses, however, a partial reversal of this effect occurred; this was accompanied by increased renal erythropoietin expression and stabilization of hypoxia-inducible factors, likely brought about by the relative anemia. Thus, hepatic and renal hypoxia-sensing pathways act in concert to modulate hemoglobin in response to nitrate, converging at an optimal minimal hemoglobin concentration appropriate to the environmental/physiologic situation. Suppression of hepatic erythropoietin expression by nitrate may thus act to decrease blood viscosity while matching oxygen supply to demand, whereas renal oxygen sensing could act as a brake, averting a potentially detrimental fall in hematocrit.—Ashmore, T., Fernandez, B. O., Evans, C. E., Huang, Y., Branco-Price, C., Griffin, J. L., Johnson, R. S., Feelisch, M., Murray, A. J. Suppression of erythropoiesis by dietary nitrate. PMID:25422368

  4. Stress corrosion cracking of zirconium in hot nitric acid

    SciTech Connect

    Kajimura, H.; Nagano, H. )

    1992-05-01

    Zirconium (Zr) has excellent general corrosion resistance in nitric acid. However, stress corrosion cracking (SCC) has been reported in concentrated nitric acid. The purpose of this paper is to evaluate the SCC susceptibility of Zr as a function of HNO[sub 3] concentration, from 6 to 94%, and temperature. The SCC mechanism was also investigated in relation to the electrochemical behavior. The slow strain rate test technique, under constant potential conditions, was mainly adopted for SCC testing. SCC did not occur in the boiling HNO[sub 3] at concentrations less than 70% unless an anodic potential was applied. The critical SCC potential, which coincides with the transient potential from passive to transpassive behavior in the polarization curve, decreased with an increase in HNO[sub 3] concentration. In boiling 94% HNO[sub 3] Zr exhibited SCC even under open-circuit potential conditions.

  5. Electrochemical protection of zirconium in oxidizing hydrochloric acid solutions

    SciTech Connect

    Yuu, T-L.; Maguire, M.

    1984-06-01

    An electrochemical protection technique using cathodic polarization to maintain zirconium below its critical repassivation potential was used to avoid pitting and stress corrosion cracking (SCC) in hydrochloric acid (HCI) containing ferric ions (Fe/sup +3/). Corrosion and pit penetration rates are reported for pickled, abraded, and as-received surface conditions in 10, 20, and 37% HCI containing 50, 100, or 500 ppm Fe/sup +3/ at temperatures to boiling. The pickled surface was the least susceptible to pitting in the 64 day tests. Electrochemical protection is then evaluated for total immersion, partial immersion, U-bend, and constant strain rate tensile tests. Protection is effective in eliminating pitting and SCC in 10 and 20% HCI containing Fe/sup +3/.

  6. Zirconium oxidation under high-energy heavy-ion irradiation

    NASA Astrophysics Data System (ADS)

    Bérerd, N.; Chevarier, A.; Moncoffre, N.; Jaffrézic, H.; Balanzat, E.; Catalette, H.

    2005-04-01

    This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions. The irradiations were performed on the IRRadiation SUD (IRRSUD) beam line at Grand Accélérateur National d'Ions Lourds of Caen. The oxygen partial pressure was fixed at 10-3Pa and two temperature conditions were used, either 480°C reached by Joule effect heating or 280°C due to Xe energy deposition. Zirconia was fully characterized by Rutherford backscattering spectrometry, scanning electron microscopy, and grazing angle x-ray diffraction. Apparent diffusion coefficients of oxygen in ZrO2 were determined from these experiments by using a model which takes into account a surface exchange between oxygen gas and the ZrO2 surface. These results are compared with thermal oxidation data.

  7. Raman spectra of zirconium oxychloride crystalline hydrate and solutions

    SciTech Connect

    Kozhevnikova, G.V.; Myund, L.A.; Burkov, K.A.

    1988-08-01

    Raman spectra of zirconium oxychloride crystalline hydrate and its deuteroanalogs in the 50-4000 cm/sup -1/ region have been obtained and examined. They have been compared with the spectra of solutions. In the region of nu/sub Zr-O/ vibrations the Raman spectrum of the solution has been resolved into its components with the aid of a computer. Spectral properties of the nu/sub Zr-OH/ and nu/sub Zr-O(H)/sub 2/) bands of the (Zr/sub 4/(OH)/sub 8/(H/sub 2/O)/sub 16/)/sup 8 +/ complexes in the crystalline hydrate and in solution have been obtained.

  8. Extraction and spectrophotometric determination of zirconium(IV)

    SciTech Connect

    Agrawal, Y.K.; John, K.T.

    1984-01-01

    A sensitive and selective method for the extraction and spectrophotometric determination of Zr(IV) with N-p-chlorophenyl-3,4,5-trimethoxycinnamohydroxamic acid (PTCHA) has been developed. The binary complex of Zr(IV)-PTCHA is extracted from 2-6 M HCl into chloroform, having a maximum absorbance at 385 nm; molar absorptivity 2.1 x 10/sup 4/ 1 mol/sup -1/ cm/sup -1/. A ternary complex with xylenol orange (Zr-PTCHA-XO) have been studied in chloroform-ethanol media, which absorbs at 540 nm; molar absorptivity 4.3 x 10/sup 4/ 1 mol/sup -1/ cm /sup -1/. The present method is applied for the analysis of zirconium in standard samples. 15 references, 3 tables.

  9. Studies on adsorption of formaldehyde in zirconium phosphate-glyphosates

    NASA Astrophysics Data System (ADS)

    Zhang, Yuejuan; Yi, Jianjun; Xu, Qinghong

    2011-01-01

    In our previous work [22], a kind of layered compound of zirconium phosphate-glyphosate (ZrGP) was synthesized. Its large surface area (445 m 2/g) indicates this compound has possible application in adsorptions. In this paper, adsorption to formaldehyde in ZrGP and mechanisms of the adsorption were studied carefully. Balance time of adsorption (about 6 h) and largest adsorbed amount (7.8%) were found when adsorption temperature was at 40 °C and pH value of adsorption environment was about 3.0. H-bonds were found existing between molecules of formaldehyde and ZrGP, and formaldehyde molecules could exist in ZrGP stably.

  10. PNIPAM grafting on the surface of zirconium phosphate

    NASA Astrophysics Data System (ADS)

    Li, Hai; Wang, Xuezhen; Cheng, Zhengdong; Cheng's Group Team, Dr.

    2015-03-01

    We are reporting for the first time the grafting of the thermoresponsive polymer PNIPAM (poly n-isoproprylacrylamide) on the surface of inorganic nanoplates zirconium phosphate. Particularly, the grafting on inorganic nanoplates using gamma rays has never scarcely been reported and yet proved to be successful in our synthesis. We proved that by gamma ray irradiation, the peroxide groups has been produced on the ZrP particles since that peroxide groups, on the surface of the hexagonal nanoplates, which upon heating initiated the free radical polymerization and subsequent attachment of PNIPAM. The presence of covalent band between ZrP and PNIPAM were observed and characterized by TGA, FTIR and solid state NMR respectively. The attachment of a thermoresponsive polymer to ZrP nanocrystals brings thus remarkable possibilities for their employment in the fields of medicine, oil industry, as well as physics.

  11. Dislocation locking versus easy glide in titanium and zirconium.

    PubMed

    Clouet, Emmanuel; Caillard, Daniel; Chaari, Nermine; Onimus, Fabien; Rodney, David

    2015-09-01

    The ease of a metal to deform plastically in selected crystallographic planes depends on the core structure of its dislocations. As the latter is controlled by electronic interactions, metals with the same valence electron configuration usually exhibit a similar plastic behaviour. For this reason, titanium and zirconium, two transition metals of technological importance from the same column of the periodic table, have so far been assumed to deform in a similar fashion. However, we show here, using in situ transmission electron microscopy straining experiments, that plasticity proceeds very differently in these two metals, being intermittent in Ti and continuous in Zr. This observation is rationalized using first-principles calculations, which reveal that, in both metals, dislocations may adopt the same set of different cores that are either glissile or sessile. An inversion of stability of these cores between Zr and Ti is shown to be at the origin of the profoundly different plastic behaviours. PMID:26147845

  12. Niobium-zirconium chronometry and early solar system development.

    PubMed

    Schönbächler, Maria; Rehkämper, Mark; Halliday, Alex N; Lee, Der-Chuen; Bourot-Denise, Michèle; Zanda, Brigitte; Hattendorf, Bodo; Günther, Detlef

    2002-03-01

    Niobium-92 (92Nb) decays to zirconium-92 (92Zr) with a half-life of 36 million years and can be used to place constraints on the site of p-process nucleosynthesis and the timing of early solar system processes. Recent results have suggested that the initial 92Nb/93Nb of the solar system was high (>10(-3)). We report Nb-Zr internal isochrons for the ordinary chondrite Estacado (H6) and a clast of the mesosiderite Vaca Muerta, both of which define an initial 92Nb/93Nb ratio of approximately 10(-5). Therefore, the solar system appears to have started with a ratio of <3 x 10(-5), which implies that Earth's initial differentiation need not have been as protracted as recently suggested. PMID:11872837

  13. Niobium-Zirconium Chronometry and Early Solar System Development

    NASA Astrophysics Data System (ADS)

    Schönbächler, Maria; Rehkämper, Mark; Halliday, Alex N.; Lee, Der-Chuen; Bourot-Denise, Michèle; Zanda, Brigitte; Hattendorf, Bodo; Günther, Detlef

    2002-03-01

    Niobium-92 (92Nb) decays to zirconium-92 (92Zr) with a half-life of 36 million years and can be used to place constraints on the site of p-process nucleosynthesis and the timing of early solar system processes. Recent results have suggested that the initial 92Nb/93Nb of the solar system was high (>10-3). We report Nb-Zr internal isochrons for the ordinary chondrite Estacado (H6) and a clast of the mesosiderite Vaca Muerta, both of which define an initial 92Nb/93Nb ratio of ~10-5. Therefore, the solar system appears to have started with a ratio of <3 × 10-5, which implies that Earth's initial differentiation need not have been as protracted as recently suggested.

  14. Titanium-Zirconium-Nickel Alloy Inside Marshall's Electrostatic Levitator (ESL)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This is a close-up of a sample of titanium-zirconium-nickel alloy inside the Electrostatic Levitator (ESL) vacuum chamber at NASA's Marshall Space Flight Center (MSFC). The ESL uses static electricity to suspend an object (about 3-4 mm in diameter) inside a vacuum chamber allowing scientists to record a wide range of physical properties without the sample contracting the container or any instruments, conditions that would alter the readings. Once inside the chamber, a laser heats the sample until it melts. The laser is then turned off and the sample cools, changing from a liquid drop to a solid sphere. Since 1977, the ESL has been used at MSFC to study the characteristics of new metals, ceramics, and glass compounds. Materials created as a result of these tests include new optical materials, special metallic glasses, and spacecraft components.

  15. Titanium-Zirconium-Nickel Alloy Inside Marshall's Electrostatic Levitator (ESL)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This Photo, which appeared on the July cover of `Physics Today', is of the Electrostatic Levitator (ESL) at NASA's Marshall Space Flight Center (MSFC). The ESL uses static electricity to suspend an object (about 3-4 mm in diameter) inside a vacuum chamber allowing scientists to record a wide range of physical properties without the sample contracting the container or any instruments, conditions that would alter the readings. Once inside the chamber, a laser heats the sample until it melts. The laser is then turned off and the sample cools, changing from a liquid drop to a solid sphere. In this particular shot, the ESL contains a solid metal sample of titanium-zirconium-nickel alloy. Since 1977, the ESL has been used at MSFC to study the characteristics of new metals, ceramics, and glass compounds. Materials created as a result of these tests include new optical materials, special metallic glasses, and spacecraft components.

  16. Nitrate removal and denitrification affected by soil characteristics in nitrate treatment wetlands.

    PubMed

    Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan; Chang, Yih-Feng; Shih, Kai-Chung

    2007-03-01

    Several small-scale surface flow constructed wetlands unplanted and planted (monoculture) with various macrophytes (Phragmites australis, Typha orientalis, Pennisetum purpureum, Ipomoea aquatica, and Pistia stratiotes) were established to continuously receive nitrate-contaminated groundwater. Soil characteristics and their effects on nitrate removal and soil denitrification were investigated. The results showed that planted wetland cells exhibited significantly higher (P < 0.05) nitrate removal efficiencies (70-99%) and soil denitrification rates (3.78-15.02 microg N2O-N/g dry soil/h) than an unplanted covered wetland cell (1%, 0.11 microg N2O-N/g/h). However, the unplanted uncovered wetland cell showed a nitrate removal efficiency (55%) lower than but a soil denitrification rate (9.12 microg N2O-N/g/h) comparable to the planted cells. The nitrate removal rate correlated closely and positively with the soil denitrification rate for the planted cells, indicating that soil denitrification is an important process for removing nitrate in constructed wetlands. The results of nitrogen budget revealed that around 68.9-90.7% of the overall nitrogen removal could be attributed to the total denitrification. The soil denitrification rate was found to correlate significantly (P < 0.01) with the extractable organic carbon, organic matter, and in situ-measured redox potential of wetland soil, which accordingly were concluded as suitable indicators of soil denitrification rate and nitrate removal rate in nitrate treatment wetlands. PMID:17365317

  17. COMPARATIVE KINETIC STUDIES OF NITRATE-LIMITED GROWTH AND NITRATE UPTAKE IN PHYTOPLANKTON IN CONTINUOUS CULTURE

    EPA Science Inventory

    A comparative kinetic study of nitrate-limited growth and nitrate uptake was carried out in chemostat cultures of Ankistrodesmus falcatus, Asterionella formosa, Fragilaria crotonensis. In each species growth rate (microgram) was related to total cell nitrogen or cell quota (q) by...

  18. Extraction of lanthanide(III) and yttrium nitrates by trialkylmethylammonium nitrate from multicomponent solutions

    SciTech Connect

    Pyartman, A.K.; Kopyrin, A.A.; Puzikov, E.A.

    1995-07-01

    The extraction of lanthanide(III) and yttrium nitrates from multicomponent solutions by trialkylmethylammonium nitrate at 298.15 K and pH 2 is examined. Physicochemical and mathematical models describing the distributions of lanthanide(III) (Pr-Lu) and Y in multicomponent solutions as a function of the total metal concentration in the aqueous phase and concentrate composition are presented.

  19. Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors.

    PubMed

    Krishna Mohan, Tulasi Venkata; Renu, Kadali; Nancharaiah, Yarlagadda Venkata; Satya Sai, Pedapati Murali; Venugopalan, Vayalam Purath

    2016-02-01

    A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy. PMID:26134447

  20. Ion beam mixing of chromium or zirconium films with sapphire

    SciTech Connect

    McHargue, C.J.; Joslin, D.L.; White, C.W.; daSilva, M.F.; Alves, E.; Soares, J.C.

    1995-12-31

    Ion beam mixing of thin metallic films deposited on sapphire substrates was studied for chromium or zirconium films deposited on single crystalline {alpha}-Al{sub 2}0{sub 3} substrates. Evidence for the influence of equilibrium thermodynamic factors was sought by comparing the effects of bombarding with oxygen ions (300 and 1073 K) with those of neon ions (300 K). Thermodynamic calculations indicate that mixing might occur for Zr/sapphire at 1073 K but not at 300 K. Chromium/sapphire should not be mixed at either temperature. The implantation energy placed the peak oxygen concentration at the metal/sapphire interface in an attempt to maintain an equilibrium ratio of cations/anions and promote a radiation-induced chemical reaction across the interface. Rutherford backscattering-ion channeling measurements indicated that the widths of ``mixed`` regions were consistent with those predicted from ballistic considerations. Other experiments employed a heavier ion (krypton) as the mixing ion (300 K) in order to increase the mixing efficiency. Rutherford backscattering-ion channeling and x-ray photoelectron spectroscopy were used to determine the extent and nature of any interface modification. XPS results indicated that only metallic chromium (Cr{sup 0}) was present near the interface before and after irradiation with Kr at 300 K. Zirconium exhibited only the metallic state (Zr{sup 0}) in the as-deposited film but was present as both Zr{sup 0} and Zr{sup 4{plus}} after irradiation. Some metallic aluminum (AI{sup O}) was detected near the Zr/sapphire interface, suggesting that a local chemical reaction between Zr and the sapphire occurred during bombardment. No long-range material transport was detected for any experimental condition examined; the width of the ``mixed` region in each case was consistent with that expected for ballistic effects.

  1. Synthesis of zirconium carbide from zircon concentrates in a thermal plasma reactor

    SciTech Connect

    Vidal, E.E.; Taylor, P.R.; Manrique, M.

    1996-10-01

    Ultrafine zirconium carbide powder has been synthesized using zircon concentrate and methane in a thermal plasma reactor. The effect of several experimental variables, such as power used and zircon particle size, on the conversion has been studied. A thermodynamic analysis of the possible reactions and stable compounds was performed. A mathematical model that describes the in-flight decomposition of zircon particles was developed based on a description of the temperature and velocity profiles calculated in the reactor. It was shown that the formation of zirconium carbide from zircon and methane is thermodynamically possible. Complete vaporization of zircon in the reactor is predicted when the particle size is below 45 {micro}m and the effective power entering the reactor is 15 kW. The powders were collected and characterized by XRD, SEM, TEM and chemical analysis using ICP. Results of the product analysis indicated the presence of zirconium carbide, zirconium oxide, silicon carbide and silicon oxide.

  2. Zirconium and hafnium tetrachloride separation by extractive distillation with molten zinc chloride lead chloride solvent

    SciTech Connect

    McLaughlin, D.F.; Stoltz, R.A.

    1988-04-12

    In an extractive distillation method for separating hafniuim tetrachloride from zirconium tetrachloride of the type wherein a mixture of zirconium and hafnium tetrachlorides is introduced into an extractive distillation column, which extractive distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a molten salt solvent is circulated into the reflux condenser and through the column to provide a liquid phase, and wherein molten salt solvent containing zirconium tetrachloride is taken from the reboiler and run through a stripper to remove zirconium tetrachloride product from the molten salt solvent and the stripped molten salt solvent is returned to the reflux condenser and hafnium tetrachloride enriched vapor is taken as product from the reflux condenser, the improvement is described comprising: the molten salt having a composition of at least 30 mole percent zinc chloride and at least 10 mole percent of lead chloride.

  3. Formation of micron and submicron structures on a zirconium oxide surface exposed to nanosecond laser radiation

    SciTech Connect

    Ganin, D V; Mikolutskiy, S I; Khomich, V Yu; Yamshchikov, V A; Tokarev, V N; Shmakov, V A

    2014-04-28

    Possibility of forming quasi-periodic structures of micron and submicron dimensions on a surface of zirconium dioxide under the action of eximer ArF laser radiation is shown experimentally and theoretically. (interaction of laser radiation with matter)

  4. Contribution of atmospheric nitrate deposition to nitrate loading in the Chesapeake Bay. Final report

    SciTech Connect

    Tyler, M.

    1988-12-01

    Recent studies have suggested that nitrate introduced into the Chesapeake Bay via atmospheric deposition may be a significant source of excess nutrients. In order to determine if concerns about atmospheric deposition are justified, modeled estimates of wetfall nitrate deposition over the Chesapeake Bay basin, based on monitoring data collected in 1984, were used to estimate basin-wide nitrate loading (1.38 x 10/sup 8/ kg) over the land area of the basin. Estimates of transfer coefficients and nitrate loadings to the Bay for various land-use categories were also calculated, using figures developed by the EPA Chesapeake Bay Program. The conservative nature of assumptions made in developing these figures suggests that the actual percentage contribution of atmospheric nitrate deposition may be lower than the estimated value.

  5. Reaction of zirconium fluoride monohydrate and ammonium bifluoride; Its effect on fluoride glass preparation and quality

    SciTech Connect

    Ewing, K.J.; Sanghera, J.S.; Miklos, R.E.; Sachon, M.G.; Pietersen, L.; Hart, P.; Aggarwal, I. . Optical Sciences Div.)

    1989-08-01

    The products obtained from the room-temperature reaction of ammonium bifluoride and zirconium fluoride monohydrate are ammonium heptafluorozirconate ((NH/sub 4/)/sub 3/ZrF/sub 7/), liquid water, and hydrogen fluoride. This paper discusses ammonium bifluoride and zirconium fluoride monohydrate reacted prior to glass batching, producing dry ammonium heptafluorozirconate which was used to prepare a high-quality ZBLAN fluoride glass.

  6. Actinide partitioning studies using dihexyl-N,N-diethycarbamolymehtyl phosphonate and dissolved zirconium calcine

    SciTech Connect

    Brewer, K.N.; Herbst, R.S.; Law, J.D.; Garn, T.G.; Tillotson, R.D.; Todd, T.A.

    1996-01-01

    A baseline flowsheet capable of partitioning the transuranic (TRU) elements from dissolved zirconium calcines has been developed. The goal of the TRU partitioning process is to remove the TRUs from solutions of dissolved zirconium calcines to below the 10 CFR 61.55 Class A waste limit of 10 nCi/g. Extraction, scrub, strip, and wash distribution coefficients for several elements, including the actinides, were measured in the laboratory by performing equal volume batch contacts. A solvent containing diheyl-N, N- diethylcarbamoylmethyl phosphonate (CMP), tributylphosphate (TBP), and a branched chain hydrocarbon as the diluent were used to develop this process. A non-radioactive zirconium pilot-plant calcine was spiked with the TRUs, U, Tc, or a radioactive isotope of zirconium to simulate the behavior of these elements in actual dissolved zirconium calcine feed. Distribution coefficient data obtained from laboratory testing were used to recommend: (1) solvent composition, (2) scrub solutions capable of selectively removing extracted zirconium while minimizing actinide recycle, (3) optimized strip solutions which quantitatively recover extracted actinides, and (4) feed adjustments necessary for flowsheet efficiency. Laboratory distribution coefficients were used in conjunction with the Generic TRUEX Model (GTM) to develop and recommend a flowsheet for testing in the 5.5-cm Centrifugal Contractor Mockup. GTM results indicate that the recommended flowsheet should remove the actinides from dissolved zirconium calcine feed to below the Class A waste limit of 10 nCi/g. Less than 0.01 wt% of the extracted zirconium will report to the high- activity waste (HAW) fraction using the 0.05 M H{sub 2}C{sub 2}O{sub 4} in 3.0 M HNO{sub 3} scrub, and greater than 99% of the extracted actinides are recovered with 0.001 M HEDPA.

  7. Co-Rolled U10Mo/Zirconium-Barrier-Layer Monolithic Fuel Foil Fabrication Process

    SciTech Connect

    G. A. Moore; M. C. Marshall

    2010-01-01

    Integral to the current UMo fuel foil processing scheme being developed at Idaho National Laboratory (INL) is the incorporation of a zirconium barrier layer for the purpose of controlling UMo-Al interdiffusion at the fuel-meat/cladding interface. A hot “co-rolling” process is employed to establish a ~25-µm-thick zirconium barrier layer on each face of the ~0.3-mm-thick U10Mo fuel foil.

  8. Ion Pairing in Alkali Nitrate Electrolyte Solutions.

    PubMed

    Xie, Wen Jun; Zhang, Zhen; Gao, Yi Qin

    2016-03-10

    In this study, we investigate the thermodynamics of alkali nitrate salt solutions, especially the formation of contact ion pairs between alkali cation and nitrate anion. The ion-pairing propensity shows an order of LiNO3 < NaNO3 < KNO3. Such results explain the salt activity coefficients and suggest that the empirical "law of matching water affinity" is followed by these alkali nitrate salt solutions. The spatial patterns of contact ion pairs are different in the three salt solutions studied here: Li(+) forms the contact ion pair with only one oxygen of the nitrate while Na(+) and K(+) can also be shared by two oxygens of the nitrate. In reproducing the salt activity coefficient using Kirkwood-Buff theory, we find that it is essential to include electronic polarization for Li(+) which has a high charge density. The electronic continuum correction for nonpolarizable force field significantly improves the agreement between the calculated activity coefficients and their experimental values. This approach also improves the performance of the force field on salt solubility. From these two aspects, this study suggests that electronic continuum correction can be a promising approach to force-field development for ions with high charge densities. PMID:26901167

  9. Proteomic Approaches to Analyze Protein Tyrosine Nitration

    PubMed Central

    Feeney, Maria B.

    2013-01-01

    Abstract Significance: The conversion of protein-bound Tyr residues to 3-nitrotyrosine (3NY) can occur during nitrative stress and has been correlated to aging and many disease states. Proteomic analysis of this post-translational modification, using mass spectrometry-based techniques, is crucial for understanding its potential role in pathological and physiological processes. Recent Advances: To overcome some of the disadvantages inherent to well-established nitroproteomic methods using anti-3NY antibodies and gel-based separations, methods involving multidimensional chromatography, precursor ion scanning, and/or chemical derivatization have emerged for both identification and quantitation of protein nitration sites. A few of these methods have successfully detected endogenous 3NY modifications from biological samples. Critical Issues: While model systems often show promising results, identification of endogenous 3NY modifications remains largely elusive. The frequently low abundance of nitrated proteins in vivo, even under inflammatory conditions, is especially challenging, and sample loss due to derivatization and cleaning may become significant. Future Directions: Continued efforts to avoid interference from non-nitrated peptides without sacrificing recovery of nitrated peptides are needed. Quantitative methods are emerging and are crucial for identifying endogenous modifications that may have significant biological impacts. Antioxid. Redox Signal. 19, 1247–1256. PMID:23157221

  10. Structural and mechanistic insights on nitrate reductases.

    PubMed

    Coelho, Catarina; Romão, Maria João

    2015-12-01

    Nitrate reductases (NR) belong to the DMSO reductase family of Mo-containing enzymes and perform key roles in the metabolism of the nitrogen cycle, reducing nitrate to nitrite. Due to variable cell location, structure and function, they have been divided into periplasmic (Nap), cytoplasmic, and membrane-bound (Nar) nitrate reductases. The first crystal structure obtained for a NR was that of the monomeric NapA from Desulfovibrio desulfuricans in 1999. Since then several new crystal structures were solved providing novel insights that led to the revision of the commonly accepted reaction mechanism for periplasmic nitrate reductases. The two crystal structures available for the NarGHI protein are from the same organism (Escherichia coli) and the combination with electrochemical and spectroscopic studies also lead to the proposal of a reaction mechanism for this group of enzymes. Here we present an overview on the current advances in structural and functional aspects of bacterial nitrate reductases, focusing on the mechanistic implications drawn from the crystallographic data. PMID:26362109

  11. Microbial Reduction of Chromate in the Presence of Nitrate by Three Nitrate Respiring Organisms

    PubMed Central

    Chovanec, Peter; Sparacino-Watkins, Courtney; Zhang, Ning; Basu, Partha; Stolz, John F.

    2012-01-01

    A major challenge for the bioremediation of toxic metals is the co-occurrence of nitrate, as it can inhibit metal transformation. Geobacter metallireducens, Desulfovibrio desulfuricans, and Sulfurospirillum barnesii are three soil bacteria that can reduce chromate [Cr(VI)] and nitrate, and may be beneficial for developing bioremediation strategies. All three organisms respire through dissimilatory nitrate reduction to ammonia (DNRA), employing different nitrate reductases but similar nitrite reductase (Nrf). G. metallireducens reduces nitrate to nitrite via the membrane bound nitrate reductase (Nar), while S. barnesii and D. desulfuricans strain 27774 have slightly different forms of periplasmic nitrate reductase (Nap). We investigated the effect of DNRA growth in the presence of Cr(VI) in these three organisms and the ability of each to reduce Cr(VI) to Cr(III), and found that each organisms responded differently. Growth of G. metallireducens on nitrate was completely inhibited by Cr(VI). Cultures of D. desulfuricans on nitrate media was initially delayed (48 h) in the presence of Cr(VI), but ultimately reached comparable cell yields to the non-treated control. This prolonged lag phase accompanied the transformation of Cr(VI) to Cr(III). Viable G. metallireducens cells could reduce Cr(VI), whereas Cr(VI) reduction by D. desulfuricans during growth, was mediated by a filterable and heat stable extracellular metabolite. S. barnesii growth on nitrate was not affected by Cr(VI), and Cr(VI) was reduced to Cr(III). However, Cr(VI) reduction activity in S. barnesii, was detected in both the cell free spent medium and cells, indicating both extracellular and cell associated mechanisms. Taken together, these results have demonstrated that Cr(VI) affects DNRA in the three organisms differently, and that each have a unique mechanism for Cr(VI) reduction. PMID:23251135

  12. Factors affecting the stress corrosion cracking susceptibility of zirconium in 90% nitric acid

    SciTech Connect

    Yau, T.L.

    1987-01-01

    U-bend, C-ring, and slow strain-rate tests have been performed to evaluate the effects of texture, stress, surface conditions, heat treatment, electrochemical potential, and strain rate on stress corrosion cracking (SCC) of zirconium in 90% nitric acid at room temperatures. It has been shown that careful control of texture, surface condition (scratching, cleaning and oxide coating), and/or applied stress can effectively lead to the prevention of SCC of zirconium in 90% HNO/sub 3/. Heat treating at 760/sup 0/C, 880/sup 0/C, or 1000/sup 0/C does not seem to improve the SCC resistance. However, if the potential of zirconium is maintained at 500 mV/sub SCE/ or lower, or 200 ppm of HF is added, zirconium's SCC susceptibility in 90% HNO/sub 3/ is eliminated. In the case of adding HF, zirconium sponge must also be added in order to avoid high corrosion rates. The mechanism for SCC of zirconium in 90% HNO/sub 3/ appears to be stress assisted local anodic dissolution, since the highest susceptibility is observed at strain rate = 7.5 x 10/sup -7//sec, and, at a higher or lower strain rate the susceptibility decreases. There is additional evidence to support this mechanism.

  13. Integrating fluctuating nitrate uptake and assimilation to robust homeostasis.

    PubMed

    Huang, Yongshun; Drengstig, Tormod; Ruoff, Peter

    2012-05-01

    Nitrate is an important nitrogen source used by plants. Despite of the considerable variation in the amount of soil nitrate, plants keep cytosolic nitrate at a homeostatic controlled level. Here we describe a set of homeostatic controller motifs and their interaction that can maintain robust cytosolic nitrate homeostasis at fluctuating external nitrate concentrations and nitrate assimilation levels. The controller motifs are divided into two functional classes termed as inflow and outflow controllers. In the presence of high amounts of environmental nitrate, the function of outflow controllers is associated to efflux mechanisms removing excess of nitrate from the cytosol that is taken up by low-affinity transporter systems (LATS). Inflow controllers on the other hand maintain homeostasis in the presence of a high demand of nitrate by the cell relative to the amount of available environmental nitrate. This is achieved by either remobilizing nitrate from a vacuolar store, or by taking up nitrate by means of high-affinity transporter systems (HATS). By combining inflow and outflow controllers we demonstrate how nitrate uptake, assimilation, storage and efflux are integrated to a regulatory network that maintains cytosolic nitrate homeostasis at changing environmental conditions. PMID:22070777

  14. Molecular Components of Nitrate and Nitrite Efflux in Yeast

    PubMed Central

    Cabrera, Elisa; González-Montelongo, Rafaela; Giraldez, Teresa; de la Rosa, Diego Alvarez

    2014-01-01

    Some eukaryotes, such as plant and fungi, are capable of utilizing nitrate as the sole nitrogen source. Once transported into the cell, nitrate is reduced to ammonium by the consecutive action of nitrate and nitrite reductase. How nitrate assimilation is balanced with nitrate and nitrite efflux is unknown, as are the proteins involved. The nitrate assimilatory yeast Hansenula polymorpha was used as a model to dissect these efflux systems. We identified the sulfite transporters Ssu1 and Ssu2 as effective nitrate exporters, Ssu2 being quantitatively more important, and we characterize the Nar1 protein as a nitrate/nitrite exporter. The use of strains lacking either SSU2 or NAR1 along with the nitrate reductase gene YNR1 showed that nitrate reductase activity is not required for net nitrate uptake. Growth test experiments indicated that Ssu2 and Nar1 exporters allow yeast to cope with nitrite toxicity. We also have shown that the well-known Saccharomyces cerevisiae sulfite efflux permease Ssu1 is also able to excrete nitrite and nitrate. These results characterize for the first time essential components of the nitrate/nitrite efflux system and their impact on net nitrate uptake and its regulation. PMID:24363367

  15. Atmospheric organic nitrate photochemistry of the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Grodzinsky, Gil

    This thesis describes the development and testing of a highly sensitive organic nitrate measurement system. Together with its predecessor, the role of organic nitrates in the photochemistry of two Southeastern metropolitan areas was evaluated over three years of field studies in Atlanta, Georgia and Nashville, Tennessee. Up to 17 different organic nitrates were measured. The field studies included the 1994 Southern Oxidants Study (SOS) NOy Intercomparison/Nashville Exploratory, 1994 Atlanta Summer Intensive, 1995 SOS Nashville/Middle Tennessee Ozone Study, 1996 Atlanta Pre-Olympic Study, and 1994 Atlanta Olympic Study. Organic nitrates can be significant contributors to total NOy and are found to be significant reservoirs of active nitrogen in these metropolitan areas. In all cases, peroxyacetyl nitrate (PAN) was found to be the predominant form of organic nitrate although significant levels (several hundred ppt to a few ppb) of other organic nitrates were also identified. These compounds included peroxypropionyl nitrate (PPN), peroxybutyryl nitrate (PnBN), peroxyisobutyryl nitrate (PiBN), and C1-C6 alkyl nitrates. Peroxymethacryoyl nitrate (MPAN), an organic nitrate believed to be produced from oxidation of the natural hydrocarbon isoprene, was also generally present. Ratios of these organic nitrates were used to determine whether ozone production in Nashville, TN and Atlanta, GA are more limited by NOx or hydrocarbon chemistry and to assess the role of natural hydrocarbon emissions in these cities.

  16. Preparation of zirconium oxy ion-imprinted particle for the selective separation of trace zirconium ion from water.

    PubMed

    Ren, Yueming; Liu, Pingxin; Liu, Xiaoli; Feng, Jing; Fan, Zhuangjun; Luan, Tianzhu

    2014-10-01

    Zr(IV) oxy ion-imprinted particle (Zr-IIP) was prepared using the metal ion imprinting technique in a sol-gel process on the surface of amino-silica. The dosages of zirconium ions as imprinted target, (3-aminopropyl) triethoxysilane (APTES) as a functional monomer and teraethyl orthosilicate (TEOS) as a cross-linker were optimized. The prepared Zr-IIP and Zr(IV) oxy ion non-imprinted particle (Zr-NIP) were characterized. pH effect, binding ability and the selectivity were investigated in detail. The results showed that the Zr-IIP had an excellent binding capacity and selectivity in the water. The equilibrium data fitted well to the pseudo-second-order kinetic and the Langmuir model for Zr(IV) binding onto Zr-IIP, respectively. The saturate binding capacity of Zr-IIP was found to be 196.08 μmol g(-1), which was 18 times higher than that of Zr-NIP. The sequence of binding efficiency of Zr-IIP for various ions was Zr(IV)>Cu(II)>Sb(III)>Eu(III). The coordination number has an important effect on the dimensional binding capacity. The equilibrium binding capacity of Zr-IIP for Zr(IV) decreased little under various concentrations of Pb(II) ions. The analysis of relative selectivity coefficient (Kr) indicated that the Zr-IIP had an appreciable binding specificity towards Zr(IV) although the competitive ions coexisted in the water. The Zr-IIP could serve as an efficient selective material for recovering or removing zirconium from the water environment. PMID:25004058

  17. Organic nitrates: past, present and future.

    PubMed

    França-Silva, Maria S; Balarini, Camille M; Cruz, Josiane C; Khan, Barkat A; Rampelotto, Pabulo H; Braga, Valdir A

    2014-01-01

    Nitric oxide (NO) is one of the most important vasodilator molecules produced by the endothelium. It has already been established that NO/cGMP signaling pathway deficiencies are involved in the pathophysiological mechanisms of many cardiovascular diseases. In this context, the development of NO-releasing drugs for therapeutic use appears to be an effective alternative to replace the deficient endogenous NO and mimic the role of this molecule in the body. Organic nitrates represent the oldest class of NO donors that have been clinically used. Considering that tolerance can occur when these drugs are applied chronically, the search for new compounds of this class with lower tolerance potential is increasing. Here, we briefly discuss the mechanisms involved in nitrate tolerance and highlight some achievements from our group in the development of new organic nitrates and their preclinical application in cardiovascular disorders. PMID:25255247

  18. Plasma nitrate and nitrite are increased by a high-nitrate supplement but not by high-nitrate foods in older adults.

    PubMed

    Miller, Gary D; Marsh, Anthony P; Dove, Robin W; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S Bruce; Kim-Shapiro, Daniel

    2012-03-01

    Little is known about the effect of dietary nitrate on the nitrate/nitrite/nitric oxide cycle in older adults. We examined the effect of a 3-day control diet vs high-nitrate diet, with and without a high-nitrate supplement (beetroot juice), on plasma nitrate and nitrite kinetics and blood pressure using a randomized 4-period crossover controlled design. We hypothesized that the high-nitrate diet would show higher levels of plasma nitrate/nitrite and lower blood pressure compared with the control diet, which would be potentiated by the supplement. Participants were 8 normotensive older men and women (5 female, 3 male, 72.5 ± 4.7 years old) with no overt disease or medications that affect nitric oxide metabolism. Plasma nitrate and nitrite levels and blood pressure were measured before and hourly for 3 hours after each meal. The mean daily changes in plasma nitrate and nitrite were significantly different from baseline for both control diet + supplement (P < .001 and P = .017 for nitrate and nitrite, respectively) and high-nitrate diet + supplement (P = .001 and P = .002), but not for control diet (P = .713 and P = .741) or high-nitrate diet (P = .852 and P = .500). Blood pressure decreased from the morning baseline measure to the three 2-hour postmeal follow-up time points for all treatments, but there was no main effect for treatment. In healthy older adults, a high-nitrate supplement consumed at breakfast elevated plasma nitrate and nitrite levels throughout the day. This observation may have practical utility for the timing of intake of a nitrate supplement with physical activity for older adults with vascular dysfunction. PMID:22464802

  19. Stochastic Controls on Nitrate Transport and Cycling

    NASA Astrophysics Data System (ADS)

    Botter, G.; Settin, T.; Alessi Celegon, E.; Marani, M.; Rinaldo, A.

    2005-12-01

    In this paper, the impact of nutrient inputs on basin-scale nitrates losses is investigated in a probabilistic framework by means of a continuous, geomorphologically based, Montecarlo approach, which explicitly tackles the random character of the processes controlling nitrates generation, transformation and transport in river basins. This is obtained by coupling the stochastic generation of climatic and rainfall series with simplified hydrologic and biogeochemical models operating at the hillslope scale. Special attention is devoted to the spatial and temporal variability of nitrogen sources of agricultural origin and to the effect of temporally distributed rainfall fields on the ensuing nitrates leaching. The influence of random climatic variables on bio-geochemical processes affecting the nitrogen cycle in the soil-water system (e.g. plant uptake, nitrification and denitrification, mineralization), is also considered. The approach developed has been applied to a catchment located in North-Eastern Italy and is used to provide probabilistic estimates of the NO_3 load transferred downstream, which is received and accumulated in the Venice lagoon. We found that the nitrogen load introduced by fertilizations significantly affects the pdf of the nitrates content in the soil moisture, leading to prolonged risks of increased nitrates leaching from soil. The model allowed the estimation of the impact of different practices on the probabilistic structure of the basin-scale hydrologic and chemical response. As a result, the return period of the water volumes and of the nitrates loads released into the Venice lagoon has been linked directly to the ongoing climatic, pluviometric and agricultural regimes, with relevant implications for environmental planning activities aimed at achieving sustainable management practices.

  20. Nitrate postdeposition processes in Svalbard surface snow

    NASA Astrophysics Data System (ADS)

    Björkman, Mats P.; Vega, Carmen P.; Kühnel, Rafael; Spataro, Francesca; Ianniello, Antonietta; Esposito, Giulio; Kaiser, Jan; Marca, Alina; Hodson, Andy; Isaksson, Elisabeth; Roberts, Tjarda J.

    2014-11-01

    The snowpack acts as a sink for atmospheric reactive nitrogen, but several postdeposition pathways have been reported to alter the concentration and isotopic composition of snow nitrate with implications for atmospheric boundary layer chemistry, ice core records, and terrestrial ecology following snow melt. Careful daily sampling of surface snow during winter (11-15 February 2010) and springtime (9 April to 5 May 2010) near Ny-Ålesund, Svalbard reveals a complex pattern of processes within the snowpack. Dry deposition was found to dominate over postdeposition losses, with a net nitrate deposition rate of (0.6 ± 0.2) µmol m-2 d-1 to homogeneous surface snow. At Ny-Ålesund, such surface dry deposition can either solely result from long-range atmospheric transport of oxidized nitrogen or include the redeposition of photolytic/bacterial emission originating from deeper snow layers. Our data further confirm that polar basin air masses bring 15N-depleted nitrate to Svalbard, while high nitrate δ(18O) values only occur in connection with ozone-depleted air, and show that these signatures are reflected in the deposited nitrate. Such ozone-depleted air is attributed to active halogen chemistry in the air masses advected to the site. However, here the Ny-Ålesund surface snow was shown to have an active role in the halogen dynamics for this region, as indicated by declining bromide concentrations and increasing nitrate δ(18O), during high BrO (low-ozone) events. The data also indicate that the snowpack BrO-NOx cycling continued in postevent periods, when ambient ozone and BrO levels recovered.

  1. Techniques for Measurement of Nitrate Movement in Soils

    NASA Technical Reports Server (NTRS)

    Broadbent, F. E.

    1971-01-01

    Contamination of surface and ground waters with nitrate usually involves leaching through soil of nitrate produced by mineralization of soil organic matter, decomposition of animal wastes or plant residues, or derived from fertilizers. Nitrate concentrations in the soil solution may be measured by several chemical procedures or by the nitrate electrode. since nitrate is produced throughout the soil mass it is difficult to identify a source of nitrate contamination by conventional means. This problem can be solved by use of N-15-enriched or N-15-depleted materials as tracers. The latter is particularly attractive because of the negligible possibility of the tracer hazardous to health.

  2. Sources of Nitrate to Tucson, Arizona Groundwaters.

    NASA Astrophysics Data System (ADS)

    Dejwakh, N.; Meixner, T.; McIntosh, J.

    2007-12-01

    The quality of groundwater is of major concern in the Southwest where water resources are scarce and we highly depend on groundwater for domestic use. Due to adverse health effects, waters with high nitrate concentrations (>45 mg/L) have been banned for domestic use by the Environmental Protection Agency. Furthermore, nitrate contamination is the leading cause for removing wells from drinking water consumption in Arizona and the United States. Therefore, it is important to consider the different sources and possible processes affecting nitrate concentration. Many studies have shown that anthropogenic sources such as agricultural fertilizers and waste water have been the dominant sources of nitrate contamination. Others have attempted to quantify the natural contributions. In this study, we focus on groundwater beneath the Tucson, Arizona basin where agricultural practices are not significant and waste water is allowed to infiltrate and recharge ground waters. We assume our groundwater to be a mixture of infiltrated rainwater, waste water and Central Arizona Project (CAP) water. We analyzed ground water samples collected along a several transects: 1) along an established flow path and 2) along two cross-sections downstream from a waste water treatment plant. In addition, surface water samples were collected from ephemeral washes during rain events, from a waste water dominated stream and from the CAP. Preliminary nitrate data show some fluxes along the first transects with an overall increase downstream (from 10 to 18 mg/L with a peak of 43.8 mg/L. In the two cross-sections downstream from the waste water, the nitrate concentrations doubled down gradient (from an average of 38 to 79 mg/L). In both transects, concentrations were highest in the middle (61 and 237 mg/L) and decreased sideways. These perplexing trends either decreasing or increasing along the flow paths cannot be explained based on geochemical concentrations alone. We are awaiting key isotopic data (d15N and d18O of nitrate). Thanks to the distinct isotopic signatures of our source waters, this data will allow us to tease apart the nitrate sources between anthropogenic and natural processes.

  3. A Reservoir of Nitrate Beneath Desert Soils

    USGS Publications Warehouse

    Walvoord, M.A.; Phillips, F.M.; Stonestrom, D.A.; Evans, R.D.; Hartsough, P.C.; Newman, B.D.; Striegl, R.G.

    2003-01-01

    A large reservoir of bioavailable nitrogen (upto ???104 kilograms of nitrogen per hectare, as nitrate) has been previously overlooked in studies of global nitrogen distribution. The reservoir has been accumulating in subsoil zones of and regions throughout the Holocene. Consideration of the subsoil reservoir raises estimates of vadose-zone nitrogen inventories by 14 to 71% for warm deserts and arid shrublands worldwide and by 3 to 16% globally. Subsoil nitrate accumulation indicates long-term leaching from desert soils, impelling further evaluation of nutrient dynamics in xeric ecosystems. Evidence that subsoil accumulations are readily mobilized raises concern about groundwater contamination after land-use or climate change.

  4. SEPARATION OF URANYL NITRATE BY EXTRACTION

    DOEpatents

    Stoughton, R.W.; Steahly, F.L.

    1958-08-26

    A process is presented for obtaining U/sup 233/ from solutions containing Pa/sup 233/. A carrier precipitate, such as MnO/sub 2/, is formed in such solutions and carries with it the Pa/sup 233/ present. This precipitate is then dissolved in nitric acid and the solution is aged to allow decay of the Pa/ sup 233/ into U/sup 233/. After a sufficient length of time the U/sup 233/ bearing solution is made 2.5 to 4.5 Molar in manganese nitrate by addition thereof, and the solution is then treated with ether to obtain uranyl nitrate by solvent extraction techniques.

  5. Nitrate isotope fractionations during biological nitrate reduction: Insights from first principles theoretical modeling

    NASA Astrophysics Data System (ADS)

    Guo, W.; Granger, J.; Sigman, D. M.

    2010-12-01

    Coupled fractionations of N and O isotopes during biological nitrate reduction provide important constraints on the marine nitrogen cycle at present and in the geologic past. Recent laboratory experiments with mono-cultures of nitrate-assimilative algae and plankton, and denitrifying bacteria demonstrate that N and O isotopic compositions of the residual nitrate co-vary linearly with a constant ratio (i.e., Δδ18O: Δδ15N) of ~1 or ~0.6 [1]. These systematic variations have been inferred to derive from the kinetic isotope fractionations associated with nitrate reductases. The isotope fractionation mechanisms at the enzymatic level, however, remain elusive. Here we present models of isotope fractionations accompanying the nitrate reduction (NO3-→NO2-) by three functional types of nitrate reductases, using techniques from ab initio, transition state and statistical thermodynamic theory. We consider three types of nitrate reductases: eukNR (eukaryotic assimilatory nitrate reductase), NAR (prokaryotic respiratory nitrate reductase) and Nap (prokaryotic periplasmic nitrate reductase). All are penta- or hexa-coordinated molybdo-enzymes, but bear considerable differences in protein geometry among functional types. Our models, based on the simplified structures of their active sites, predict N and O isotope effects (15ɛ and 18ɛ) ranging from 32.7 to 36.6‰ and from 33.5 to 34.8‰, respectively, at 300K with 18ɛ:15ɛ ratios of 0.9-1.1. The predicted amplitudes of N and O isotope fractionations are in the range measured for eukNR in vitro (~27‰, Karsh et al. in prep), and also correspond to the upper amplitudes observed for denitrifiers in vivo (~25‰, [1]). Moreover, the computed 18ɛ:15ɛ ratios corroborate the consistent relationships of ~1 observed experimentally for eukNR and the respiratory NAR. These findings indicate the enzymatic reduction is likely the rate-limiting step in most biological nitrate reductions. In addition, the predicted similarity of 18ɛ:15ɛ ratios among different nitrate reductases suggests that the nitrate isotope fractionations by nitrate reductases are governed by the kinetics of the O-N bond cleavage, which incurs negligible differences from variations in surrounding moieties at the active sites. However, our model similarly predicts a 15ɛ of 36.6‰ and 18ɛ:15ɛ of 0.9 for the auxiliary Nap, although it exhibits a 15ɛ of ~15‰ and 18ɛ:15ɛ of ~0.6 in vivo [1]. This discrepancy is suspected to arise from slower binding and release of NO3- from Nap, which could be partially rate-determining in this enzymatic catalysis, or from the assumptions of our modeled enzyme structures. By extending our above models to include the multiply-substituted (clumped) isotopologues, we predict that isotope fractionations during biological nitrate reduction decrease the proportion of 15N-18O bonds in the residual nitrate relative to their expected equilibrium abundances (~0.02‰ decrease for every 1‰ kinetic enrichment in nitrate δ15N). Future quantification of 15N-18O clumped isotope anomalies in natural nitrate may provide additional constraints on the nitrogen cycle in the ocean. Reference: [1] Granger et al. (2010) GCA, 74: 1030-1040.

  6. The role of nitrate reductase in the regulation of the nitrate assimilation pathway in the yeast Hansenula polymorpha.

    PubMed

    Navarro, Francisco J; Perdomo, Germán; Tejera, Paula; Medina, Braulio; Machín, Félix; Guillén, Rosa Maria; Lancha, Ana; Siverio, José M

    2003-11-01

    The role of nitrate reductase (NR) in the regulation of the nitrate assimilation pathway was evaluated in the yeast Hansenula polymorpha. Posttranscriptional regulation of NR in response to reduced nitrogen sources and the effect of a heterologous NR on the transcriptional regulation of nitrate-assimilatory gene expression was examined. The strain bearing YNR1 (nitrate reductase gene) under the control of the methanol-induced MOX (methanol oxidase) promoter showed that NR is active in the presence of reduced nitrogen sources. In cells incubated with glutamine plus nitrate, rapamycin abolished nitrogen catabolite repression, NR activity being very similar to that in cells induced by nitrate alone. This reveals the involvement of the Tor-signalling pathway in the transcriptional regulation of H. polymorpha nitrate assimilation genes. To assess the role of NR in nitrate-assimilatory gene expression, different strains lacking YNR1, or both YNR1 and YNT1 (high-affinity nitrate transporter) genes, or expressing the tobacco NR under the YNR1 promoter, were used. Tobacco NR abolished the constitutive nitrate-assimilatory gene induction shown by an NR gene disruptant strain. Moreover, in strains lacking the high-affinity nitrate transporter and NR this deregulation disappeared. These facts discard the role of NR protein in the transcriptional induction of the nitrate-assimilatory genes and point out the involvement of the high-affinity nitrate transporter as a part of the nitrate-signalling pathway. PMID:14613879

  7. The Acid Catalyzed Nitration of Methanol: Formation of Methyl Nitrate via Aerosol Chemistry

    NASA Technical Reports Server (NTRS)

    Riffel, Brent G.; Michelsen, Rebecca R.; Iraci, Laura T.

    2004-01-01

    The liquid phase acid catalyzed reaction of methanol with nitric acid to yield methyl nitrate under atmospheric conditions has been investigated using gas phase infrared spectroscopy. This nitration reaction is expected to occur in acidic aerosol particles found in the upper troposphere/lower stratosphere as highly soluble methanol and nitric acid diffuse into these aerosols. Gaseous methyl nitrate is released upon formation, suggesting that some fraction of NO(x) may he liberated from nitric acid (methyl nitrate is later photolyzed to NO(x)) before it is removed from the atmosphere by wet deposition. Thus, this reaction may have important implications for the NO(x) budget. Reactions have been initiated in 45-62 wt% H2SO4 solutions at 10.0 C. Methyl nitrate production rates increased exponentially with acidity within the acidity regime studied. Preliminary calculations suggest that the nitronium ion (NO2(+) is the active nitrating agent under these conditions. The reaction order in methanol appears to depend on the water/methanol ratio and varies from first to zeroth order under conditions investigated. The nitration is first order in nitronium at all acidities investigated. A second order rate constant, kappa(sub 2), has been calculated to be 1 x 10(exp 8)/ M s when the reaction is first order in methanol. Calculations suggest the nitration is first order in methanol under tropospheric conditions. The infinitesimal percentage of nitric acid in the nitronium ion form in this acidity regime probably makes this reaction insignificant for the upper troposphere; however, this nitration may become significant in the mid stratosphere where colder temperatures increase nitric acid solubility and higher sulfuric acid content shifts nitric acid speciation toward the nitronium ion.

  8. Effect of Ammonium and Nitrate on Ferric Chelate Reductase and Nitrate Reductase in Vaccinium Species

    PubMed Central

    POONNACHIT, U.; DARNELL, R.

    2004-01-01

    • Background and Aims Most Vaccinium species have strict soil requirements for optimal growth, requiring low pH, high iron availability and nitrogen primarily in the ammonium form. These soils are limited and are often located near wetlands. Vaccinium arboreum is a wild species adapted to a wide range of soils, including high pH, low iron, and nitrate‐containing soils. This broader soil adaptation in V. arboreum may be related to increased efficiency of iron or nitrate uptake compared with the cultivated Vaccinium species. • Methods Nitrate, ammonium and iron uptake, and nitrate reductase (NR) and ferric chelate reductase (FCR) activities were compared in two Vaccinium species grown hydroponically in either nitrate or ammonia, with or without iron. The species studied were the wild V. arboreum and the cultivated V. corymbosum interspecific hybrid, which exhibits the strict soil requirements of most Vaccinium species. • Key Results Ammonium uptake was significantly greater than nitrate uptake in both species, while nitrate uptake was greater in the wild species, V. arboreum, compared with the cultivated species, V. corymbosum. The increased nitrate uptake in V. arboreum was correlated with increased root NR activity compared with V. corymbosum. The lower nitrate uptake in V. corymbosum was reflected in decreased plant dry weight in this species compared with V. arboreum. Root FCR activity increased significantly in V. corymbosum grown under iron‐deficient conditions, compared with the same species grown under iron‐sufficient conditions or with V. arboreum grown under either iron condition. • Conclusions. V. arboreum appears to be more efficient in acquiring nitrate compared with V. corymbosum, possibly due to increased NR activity and this may partially explain the wider soil adaptation of V. arboreum. PMID:14980973

  9. Nitrate Uptake and Assimilation by Wheat Seedlings during Initial Exposure to Nitrate.

    PubMed

    Ashley, D A; Jackson, W A; Volk, R J

    1975-06-01

    Nitrate uptake, reduction, and translocation were examined in intact, 14-day-old, nitrogen-depleted wheat (Triticum vulgare var. Knox) seedlings during a 9-hour exposure to 0.2 mm Ca (NO(3))(2). The nitrate uptake rate was low during the initial 3-hour period, increased during the 3- to 6-hour period, and then declined. By the 3rd hour, 14% of the absorbed nitrate had been reduced, and this increased to 36% by the 9th hour. Shoots accumulated reduced (15)N more rapidly than roots and the ratio of reduced (15)N to (15)N-nitrate was higher in the shoots. A significant proportion of the total reduction occurred in the root system under these experimental conditions. Accumulation of (15)N in ethanol-insoluble forms was evident in both roots and shoots by the 3rd hour and, after 4.5 hours, increased more rapidly in shoots than in roots.An experiment in which a 3-hour exposure to 0.2 mm Ca ((15)NO(3))(2) was followed by a 12-hour exposure to 0.2 mm Ca ((14)NO(3))(2) revealed a half-time of depletion of root nitrate of about 2.5 hours. A large proportion of this depletion, however, was due to loss of (15)N-nitrate to the ambient (14)N-nitrate solution. The remaining pool of (15)N-nitrate was only slowly available for reduction. Total (15)N translocation to the shoot was relatively efficient during the first 3 hours after transfer to Ca ((14)NO(3))(2) but it essentially ceased after that time in spite of significant pools of (15)N-nitrate and alpha-amino-(15)N remaining in the root tissue. PMID:16659219

  10. Effect of temperature & salt concentration on salt tolerant nitrate-perchlorate reducing bacteria: Nitrate degradation kinetics.

    PubMed

    Ebrahimi, Shelir; Nguyen, Thi Hau; Roberts, Deborah J

    2015-10-15

    The sustainability of nitrate-contaminated water treatment using ion-exchange processes can be achieved by regenerating the exhausted resin several times. Our previous study shows that the use of multi-cycle bioregeneration of resin enclosed in membrane is an effective and innovative regeneration method. In this research, the effects of two independent factors (temperature and salt concentration) on the biological denitrification rate were studied. The results of this research along with the experimental results of the previous study on the effect of the same factors on nitrate desorption rate from the resin allow the optimization of the bioregeneration process. The results of nitrate denitrification rate study show that the biodegradation rate at different temperature and salt concentration is independent of the initial nitrate concentration. At each specific salt concentration, the nitrate removal rate increased with increasing temperature with the average value of 0.001110 ± 0.0000647 mg-nitrate/mg-VSS.h.°C. However, the effect of different salt concentrations was dependent on the temperature; there is a significant interaction between salt concentration and temperature; within each group of temperatures, the nitrate degradation rate decreased with increasing the salt concentration. The temperature affected the tolerance to salinity and culture was less tolerant to high concentration of salt at low temperature. Evidenced by the difference between the minimum and maximum nitrate degradation rate being greater at lower temperature. At 35 °C, a 32% reduction in the nitrate degradation rate was observed while at 12 °C this reduction was 69%. This is the first published study to examine the interaction of salt concentration and temperature during biological denitrification. PMID:26188598

  11. Evaluation of Nitrate Sources and Nitrate Management Strategies in California Suburban Growth Areas

    NASA Astrophysics Data System (ADS)

    Singleton, M. J.; Moran, J. E.; Esser, B. K.; Leif, R. N.; McNab, W. W.; Carle, S. F.; Moore, K. B.

    2005-12-01

    Population growth in California has pushed the boundaries of suburban communities into formerly agricultural areas. As a result there is considerable uncertainty as to whether nitrate contamination in groundwater wells results from current sources or is a legacy of agriculture. Fertilizer application for historical agriculture is frequently assumed to be a major source, but septic system leachate, other animal waste, and residential fertilizer application may also contribute. Potential remediation strategies may include improved fertilizer management and/or conversion from septic tanks to sewer systems, but the sources of nitrate and pathways to groundwater must first be identified in order to develop a plan of action. We combine the detection of trace organic compounds that are specific to domestic waste with isotopic compositions of nitrogen and oxygen in nitrate in order to determine nitrate sources. Under anaerobic conditions and in the presence of an electron donor such as organic carbon, microbially mediated denitrification may transform nitrate to harmless nitrogen gas, and fractionate the isotopologues of any residual nitrate. The occurrence of saturated zone denitrification is detected by measuring excess dissolved nitrogen gas with a field-portable membrane inlet mass spectrometer system. Groundwater age dating using the 3H/3He method provides a means of tracking the history of nitrate inputs to groundwater, including changes in nitrate flux after implementation of a remediation program. Groundwater that pre-dates agricultural or suburban activity is used to define natural background levels of nitrate. Study areas in California include Chico, Livermore, and Gilroy. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  12. Concept Feasibility Report for Electroplating Zirconium onto Uranium Foil - Year 2

    SciTech Connect

    Coffey, Greg W.; Meinhardt, Kerry D.; Joshi, Vineet V.; Pederson, Larry R.; Lavender, Curt A.; Burkes, Douglas

    2015-03-01

    The Fuel Fabrication Capability within the U.S. High Performance Research Reactor Conversion Program is funded through the National Nuclear Security Administration (NNSA) NA-26 (Office of Material Management and Minimization). An investigation was commissioned to determine the feasibility of using electroplating techniques to apply a coating of zirconium onto depleted uranium/molybdenum alloy (U-10Mo). Electroplating would provide an alternative method to the existing process of hot roll-bonding zirconium foil onto the U-10Mo fuel foil during the fabrication of fuel elements for high-performance research reactors. The objective of this research was to develop a reproducible and scalable plating process that will produce a uniform, 25 μm thick zirconium metal coating on U-10Mo foil. In previous work, Pacific Northwest National Laboratory (PNNL) established a molten salt electroplating apparatus and protocol to plate zirconium metal onto molybdenum foil (Coffey 2015). During this second year of the research, PNNL furthered this work by moving to the U-10Mo alloy system (90 percent uranium:10 percent molybdenum). The original plating apparatus was disassembled and re-assembled in a laboratory capable of handling low-level radioactive materials. Initially, the work followed the previous year’s approach, and the salt bath composition was targeted at the eutectic composition (LiF:NaF:ZrF4 = 26:37:37 mol%). Early results indicated that the formation of uranium fluoride compounds would be problematic. Other salt bath compositions were investigated in order to eliminate the uranium fluoride production (LiF:NaF = 61:39 mol% and LiF:NaF:KF = 46.5:11.5:42 mol% ). Zirconium metal was used as the crucible for the molten salt. Three plating methods were used—isopotential, galvano static, and pulsed plating. The molten salt method for zirconium metal application provided high-quality plating on molybdenum in PNNL’s previous work. A key advantage of this approach is that plating can be performed under conditions that would greatly reduce the quantity of intermetallics that form at the interface between the zirconium and U-10Mo; unlike roll bonding, the molten salt plating approach would allow for complete coverage of the U-10Mo foil with zirconium. When utilizing the experimental parameters developed for zirconium plating onto molybdenum, a uranium fluoride reaction product was formed at the Zr/U-10Mo interface. By controlling the initial plating potential, the uranium fluoride could be prevented; however, the targeted zirconium thickness (25 ±12.5 μm) could not be achieved while maintaining 100% coverage.

  13. Modeling of sink-induced irradiation growth of single-crystal and polycrystal zirconiums in nuclear reactors

    NASA Astrophysics Data System (ADS)

    Choi, Sang Il; Lee, Gyeong-Geun; Kwon, Junhyun; Kim, Ji Hyun

    2016-01-01

    The objective of this study is irradiation growth modeling of polycrystal zirconium using the advanced mean-field rate theory (MFRT) and growth equation. Since the 1960s, irradiation growth of zirconium has been among the most important phenomena in nuclear reactors. However, there is no general irradiation growth model that can explain changes in both the microstructure morphology and growth strain in polycrystal zirconium owing to lack of knowledge of the relevant atomistic information and MFRT. Although two groups have developed a single-crystal zirconium irradiation growth model, a general polycrystal zirconium model has not been developed. In this study, therefore, the defect flux was calculated using the MFRT, and the dislocation loop density was calculated from the defect flux. Moreover, the bias factor for each sink (dislocation lines, loops, and grain boundaries) was adopted in the MFRT. In addition, dislocation line and grain boundary effects were examined in polycrystal zirconiums. Finally, irradiation growth equation was established and growth strain was calculated using the average strain factor and anisotropy factor considering grain-interaction. For single-crystal zirconium and cold-worked polycrystal zirconium, irradiation growth strain results show good agreement with the experimental results. For annealed polycrystal zirconium, the results deviate from the experimental results.

  14. COGEMA Experience in Uranous Nitrate Preparation

    SciTech Connect

    Tison, E.; Bretault, Ph.

    2006-07-01

    Separation and purification of plutonium by PUREX process is based on a sequence of extraction and back extraction which requires reducing plutonium Pu IV (extractable form) into Pu III (inextractable form) Different reducers can be used to reduce Pu IV into Pu III. Early plants such as that for Magnox fuel at Sellafield used ferrous sulfamate while UP 1 at Marcoule used uranous sulfamate. These reducers are efficient and easy to prepare but generates ferric and/or sulphate ions and so complicates management of the wastes from the plutonium purification cycle. Recent plants such as UP3 and UP2 800 at La Hague, THORP at Sellafield, and RRP at Rokkasho Mura (currently under tests) use uranous nitrate (U IV) stabilized by hydrazinium nitrate (N{sub 2}H{sub 5}NO{sub 3}) and hydroxyl ammonium nitrate (HAN). In the French plants, uranous nitrate is used in U-Pu separation and alpha barrier and HAN is used in Pu purification. Compared to sulfamate, U IV does not generate extraneous chemical species and uranyl nitrate (U VI) generated by reducing Pu IV follows the main uranium stream. More over uranous nitrate is prepared from reprocessed purified uranyl nitrate taken at the outlet of the reprocessing plant. Hydrazine and HAN offer the advantage to be salt-free reagents. Uranous nitrate can be generated either by electrolysis or by catalytic hydrogenation process. Electrolytic process has been implemented in early plant UP 1 at Marcoule (when changing reducer from uranous sulfamate to uranous nitrate) and was used again in UP2 plant at La Hague. However, the electrolytic process presented several disadvantages such as a low conversion rate and problems associated with the use of mercury. Electrolysis cells with no mercury were developed for the Eurochemic plant in Belgium and then implemented in the first Japanese reprocessing plant in Tokai-Mura. But finally, in 1975, the electrolytic process was abandoned in favor of the catalytic hydrogenation process developed at La Hague. The yield of the operation and its simplicity were the main reasons for this choice. Nowadays, our catalytic hydrogenation process is used in all the commercial reprocessing plants worldwide: THORP at Sellafield, UP3 and UP2 800 at La Hague, and RRP at Rokkasho-Mura. In this process, uranyl nitrate is reduced to uranous nitrate by hydrogen in presence of a platinum based catalyst. Most of the plants implement the reaction in the same kind of reactor: 'co-current, up-flow and fixed-bed reactor'. For UP2 800 at La Hague, started in 1994, a new kind of reactor allowing a higher capacity has been developed. In this reactor, the catalyst bed is not fixed but circulating (fluidized bed). The aim of the paper is to describe both reactor technology implemented in La Hague (fixed bed and fluidized bed), to show their performance in terms of capacity and yield and to compare their operating and maintenance principles. (authors)

  15. Carbon-fluorine bond cleavage by zirconium metal hydride complexes

    SciTech Connect

    Edelbach, B.L.; Rahman, A.K.F.; Lachicotte, R.J.; Jones, W.D.

    1999-08-02

    The use of transition metal complexes to cleave strong carbon-fluorine bonds has blossomed in the past several years. Many late transition metal complexes with electron-donating ligands are believed to undergo oxidative addition to the C-F bond of a fluorinated aromatic group. The zirconium hydride dimer [Cp{sub 2}ZrH{sub 2}]{sub 2} reacts with C{sub 6}F{sub 6} at ambient temperature to give Cp{sub 2}Zr(C{sub 6}F{sub 5})F as the major product along with Cp{sub 2}ZrF{sub 2}, C{sub 6}F{sub 5}H and H{sub 2}. Neither the reaction rate nor the product ratio is affected by changes in H{sub 2} pressure or the concentration of C{sub 6}F{sub 6}. The reaction follows zero-order kinetics. The new compound Cp{sub 2}Zr(C{sub 6}F{sub 5})F has been structurally characterized. [Cp{sub 2}ZrH{sub 2}]{sub 2} reacts with C{sub 6}F{sub 5}H to give Cp{sub 2}Zr(p-C{sub 6}F{sub 4}H)F, Cp{sub 2}ZrF{sub 2}, C{sub 6}F{sub 4}H{sub 2}, and H{sub 2}. The zirconium hydride Cp{sub 3}ZrH has been structurally characterized and also reacts with C{sub 6}F{sub 6}. The products of the reaction are CpH, Cp{sub 2}Zr(C{sub 6}F{sub 5})F, C{sub 6}F{sub 5}H, Cp{sub 2}ZrF{sub 2}, Cp{sub 4}Zr, and Cp{sub 3}ZrF. The reaction rate is first order in [Cp{sub 3}ZrH] and [C{sub 6}F{sub 6}], but the product ratio is unaffected by the concentration of C{sub 6}F{sub 6}. Possible mechanisms of these reactions are discussed.

  16. Denitration of High Nitrate Salts Using Reductants

    SciTech Connect

    HD Smith; EO Jones; AJ Schmidt; AH Zacher; MD Brown; MR Elmore; SR Gano

    1999-05-03

    This report describes work conducted by Pacific Northwest National Laboratory (PNNL), in conjunction with Idaho National Engineering and Environmental Laboratory (INEEL), to remove nitrates in simulated low-activity waste (LAW). The major objective of this work was to provide data for identifying and demonstrating a technically viable and cost-effective approach to condition LAW for immobilization (grout).

  17. Iron, nitrate uptake by phytoplankton, and mermaids

    NASA Astrophysics Data System (ADS)

    Banse, Karl

    1991-11-01

    The critique by Martin et al. (this issue) of my recalculation of rates of nitrate uptake, and hence of algal division, from the Gulf of Alaska is shown to be incorrect. Neither can iron deficiency, if any, be shown to be connected with the demise of mermen and mermaids, although for different reasons.

  18. Nitrates, Nitrites, and Health. Bulletin 750.

    ERIC Educational Resources Information Center

    Deeb, Barbara S.; Sloan, Kenneth W.

    This review is intended to assess available literature in order to define the range of nitrate/nitrite effects on animals. Though the literature deals primarily with livestock and experimental animals, much of the contemporary research is concerned with human nitrite intoxication. Thus, the effects on man are discussed where appropriate. Some of

  19. 76 FR 11273 - Ammonium Nitrate From Russia

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-01

    ... nitrate from Russia (71 FR 17080). The Commission is now conducting a second review to determine whether... recently amended at 74 FR 2847 (January 16, 2009). \\1\\ No response to this request for information is... (65 FR 37759, June 16, 2000). Following five-year reviews by Commerce and the Commission,...

  20. 76 FR 47238 - Ammonium Nitrate From Russia

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-04

    ...)). Background The Commission instituted this review on March 1, 2011 (76 FR 11273) and determined on June 6, 2011 that it would conduct an expedited review (76 FR 34749, June 14, 2011). The Commission transmitted... COMMISSION Ammonium Nitrate From Russia Determination On the basis of the record \\1\\ developed in the...

  1. Nitrates, Nitrites, and Health. Bulletin 750.

    ERIC Educational Resources Information Center

    Deeb, Barbara S.; Sloan, Kenneth W.

    This review is intended to assess available literature in order to define the range of nitrate/nitrite effects on animals. Though the literature deals primarily with livestock and experimental animals, much of the contemporary research is concerned with human nitrite intoxication. Thus, the effects on man are discussed where appropriate. Some of…

  2. Negative ion spectrometry for detecting nitrated explosives

    NASA Technical Reports Server (NTRS)

    Boettger, H. G.; Yinon, J.

    1975-01-01

    Ionization procedure is modified to produce mainly negative ions by electron capture. Peaks of negative ions are monitored conventionally. Nitrated organic materials could be identified directly from sample sniff inlet stream by suitably modified mass spectrometer because of unique electronegativity which nitro group imparts to organic material.

  3. SOIL DEVELOPMENT AND NITRATES IN MINESOIL

    EPA Science Inventory

    Samples of minesoils from 16- and 40-year-old mine spoil piles were analyzed in the laboratory for various chemical and physical properties to ascertain to what extent the material have been influenced by pedogenic processes during their relatively brief time of exposure. Nitrate...

  4. A toxicological study of gadolinium nitrate

    SciTech Connect

    London, J.E.

    1988-05-01

    The sensitization study in the guinea pig did not show gadolinium nitrate to have potential sensitizing properties. Skin application studies in the rabbit demonstrated that it was cutaneously a severe irritant. This material was considered an irritant in the rabbit eye application studies. 3 refs., 1 tab.

  5. Nitrate Salt Surrogate Blending Scoping Test Plan

    SciTech Connect

    Anast, Kurt Roy

    2015-11-13

    Test blending equipment identified in the “Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing”. Determine if the equipment will provide adequate mixing of zeolite and surrogate salt/Swheat stream; optimize equipment type and operational sequencing; impact of baffles and inserts on mixing performance; and means of validating mixing performance

  6. 76 FR 70366 - Ammonium Nitrate Security Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ... Department previously announced a series of public meetings on the same topic on October 2, 2011 (see 76 FR... public comment on August 3, 2011. See 73 FR 64280 (advance notice of proposed rulemaking); 76 FR 46908... the Department's Ammonium Nitrate Security Program Web site, at...

  7. Enzyme catalytic nitration of aromatic compounds.

    PubMed

    Kong, Mingming; Wang, Kun; Dong, Runan; Gao, Haijun

    2015-06-01

    Nitroaromatic compounds are important intermediates in organic synthesis. The classic method used to synthesize them is chemical nitration, which involves the use of nitric acid diluted in water or acetic acid, both harmful to the environment. With the development of green chemistry, environmental friendly enzyme catalysis is increasingly employed in chemical processes. In this work, we adopted a non-aqueous horseradish peroxidase (HRP)/NaNO2/H2O2 reaction system to study the structural characteristics of aromatic compounds potentially nitrated by enzyme catalysis, as well as the relationship between the charges on carbon atoms in benzene ring and the nitro product distribution. Investigation of various reaction parameters showed that mild reaction conditions (ambient temperature and neutral pH), plus appropriate use of H2O2 and NaNO2 could prevent inactivation of HRP and polymerization of the substrates. Compared to aqueous-organic co-solvent reaction media, the aqueous-organic two-liquid phase system had great advantages in increasing the dissolved concentration of substrate and alleviating substrate inhibition. Analysis of the aromatic compounds' structural characteristics indicated that substrates containing substituents of NH2 or OH were readily catalyzed. Furthermore, analysis of the relationship between natural bond orbital (NBO) charges on carbon atoms in benzene ring, as calculated by the density functional method, and the nitro product distribution characteristics, demonstrated that the favored nitration sites were the ortho and para positions of substituents in benzene ring, similar to the selectivity of chemical nitration. PMID:26002502

  8. Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Li, H. F.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-04-01

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10‑6 cm3·g‑1–1.29 × 10‑6 cm3·g‑1 for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10‑6 cm3·g‑1, CP Ti and Ti–6Al–7Nb, ~3.0 × 10‑6 cm3·g‑1), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10‑6 cm3·g‑1). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments.

  9. Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility.

    PubMed

    Li, H F; Zhou, F Y; Li, L; Zheng, Y F

    2016-01-01

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co-Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10(-6) cm(3)·g(-1)-1.29 × 10(-6) cm(3)·g(-1) for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti-6Al-4V, ~3.5 × 10(-6) cm(3)·g(-1), CP Ti and Ti-6Al-7Nb, ~3.0 × 10(-6) cm(3)·g(-1)), and one-sixth that of Co-Cr alloys (Co-Cr-Mo, ~7.7 × 10(-6) cm(3)·g(-1)). Among the Zr-Ru alloy series, Zr-1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr-Ru alloy system as therapeutic devices under MRI diagnostics environments. PMID:27090955

  10. Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility

    PubMed Central

    Li, H.F.; Zhou, F.Y.; Li, L.; Zheng, Y.F.

    2016-01-01

    In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co–Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10−6 cm3·g−1–1.29 × 10−6 cm3·g−1 for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti–6Al–4V, ~3.5 × 10−6 cm3·g−1, CP Ti and Ti–6Al–7Nb, ~3.0 × 10−6 cm3·g−1), and one-sixth that of Co–Cr alloys (Co–Cr–Mo, ~7.7 × 10−6 cm3·g−1). Among the Zr–Ru alloy series, Zr–1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr–Ru alloy system as therapeutic devices under MRI diagnostics environments. PMID:27090955

  11. Investigation of desert subsoil nitrate in Northeastern Badia of Jordan.

    PubMed

    Al-Taani, Ahmed A; Al-Qudah, Khaldoun A

    2013-01-01

    High levels of naturally occurring nitrate were observed under desert pavement surfaces in NE Badia of Jordan. The subsoil nitrate inventory varies from about 24,351 to 28,853 kg NO(3)(-)/ha to a depth of 60 cm which is more than two times greater than nitrate in nonpavement soils, although both soils occurred within similar landscape and microclimate conditions. The results indicated that pavement particle size and cover percent are the primary factors contributing to the observed variations in nitrate accumulation. Desert pavement soils fully covered with fine clasts showed higher nitrate concentrations compared to soils moderately covered with coarse-grained pavements. The results also showed that high levels of nitrate were generally reached between 20 and 30 cm depth before the concentrations decreased. Chloride showed distribution profiles similar to those of nitrate. No observable difference was observed in nitrate level under desert pavement with abundant lichens compared to non-lichen pavement surface. PMID:23178770

  12. Perchlorate and nitrate in situ bioremediation of ground water

    SciTech Connect

    Strietelmeier, E. A.; Nuttall, H. Eric; Hatzinger, Paul; Goltz, Mark

    2002-01-01

    Nitrate and perchlorate are growing worldwide problems as mobile anionic groundwater contaminants. Biological rduction of nitrate and perchlorate in groundwater is under development as a technology to address these problems.

  13. Nitrated phenols in the atmosphere: a review

    NASA Astrophysics Data System (ADS)

    Harrison, Mark A. J.; Barra, Silvia; Borghesi, Daniele; Vione, Davide; Arsene, Cecilia; Iulian Olariu, Romeo

    2005-01-01

    This paper reviews the data concerning the atmospheric occurrence of nitrophenols, both in the gas and in the condensed phase (rainwater, cloud, fog and snow). Data obtained from field campaigns are reported, together with a description of the analytical techniques employed for the identification and quantification of nitrophenols. Analysis is usually performed using techniques such as High Performance Liquid Chromatography (HPLC) or Gas Chromatography-Mass Spectrometry (GC-MS), with the sampling method largely determined according to the matrix under investigation. The sources of atmospheric nitrophenols include direct emissions resulting from combustion processes, hydrolysis of pesticides (e.g. parathion) and the secondary formation of nitrophenols in the atmosphere. Atmospheric nitration of phenol can take place both in the gas and liquid phases, but the relative importance of these processes is still under discussion. The gas-phase nitration involves reaction between phenol and radOH+radNO2 during the day or radNO3+radNO2 during the night. Gas-phase nitration during the day yields only 2-nitrophenol (2-NP); while during the night it is thought that both 2-NP and 4-nitrophenol (4-NP) may be formed. Because of many gaps in the experimental evidence it is apparent that more research is required to indicate whether the 4-NP present in the environment can be accounted for by this nighttime process. Nitration in the condensed phase can be initiated by electrophilic nitration agents such as N2O5 and ClNO2. Other liquid-phase processes can also take place, in the presence of radNO3, nitrate and nitrite, in the dark and under irradiation. Condensed-phase processes have been shown to yield 2- and 4-NP in similar amounts. It is also important to consider the atmospheric sinks of nitrophenols. The rate constant for the reaction between 2-NP and radOH in the gas phase is rather low (9.010-13 cm3 molecule-1 s-1), while incomplete data are available for the reaction with radNO3. In addition, condensed-phase processes might also represent an important nitrophenol sink. Potential loss routes include the reaction with radicals such as radOH and radNO3 in aqueous solution as well as the nitration to form the dinitrophenols.

  14. The Arabidopsis NRG2 Protein Mediates Nitrate Signaling and Interacts with and Regulates Key Nitrate Regulators[OPEN

    PubMed Central

    Zhao, Lufei; Zhang, Chengfei; Li, Zehui; Lei, Zhao; Liu, Fei; Guan, Peizhu; Crawford, Nigel M.

    2016-01-01

    We show that NITRATE REGULATORY GENE2 (NRG2), which we identified using forward genetics, mediates nitrate signaling in Arabidopsis thaliana. A mutation in NRG2 disrupted the induction of nitrate-responsive genes after nitrate treatment by an ammonium-independent mechanism. The nitrate content in roots was lower in the mutants than in the wild type, which may have resulted from reduced expression of NRT1.1 (also called NPF6.3, encoding a nitrate transporter/receptor) and upregulation of NRT1.8 (also called NPF7.2, encoding a xylem nitrate transporter). Genetic and molecular data suggest that NRG2 functions upstream of NRT1.1 in nitrate signaling. Furthermore, NRG2 directly interacts with the nitrate regulator NLP7 in the nucleus, but nuclear retention of NLP7 in response to nitrate is not dependent on NRG2. Transcriptomic analysis revealed that genes involved in four nitrogen-related clusters including nitrate transport and response to nitrate were differentially expressed in the nrg2 mutants. A nitrogen compound transport cluster containing some members of the NRT/PTR family was regulated by both NRG2 and NRT1.1, while no nitrogen-related clusters showed regulation by both NRG2 and NLP7. Thus, NRG2 plays a key role in nitrate regulation in part through modulating NRT1.1 expression and may function with NLP7 via their physical interaction. PMID:26744214

  15. Approximate prediction of melting point of nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds.

    PubMed

    Keshavarz, Mohammad Hossein

    2006-12-01

    A simple new procedure is introduced to predict melting point of selected class of energetic compounds containing nitramines, nitrate esters, nitrate salts and nitroaliphatics energetic compounds. The number of nitrogen and oxygen as well as the number of nitramine group and the contribution of some specific functional groups would be needed in the new method. Energetic compounds should contain at least one of the functional groups including N-NO(2), C-ONO(2) or nonaromatic C-NO(2). Calculated melting point for 33 nitramines, nitrate esters, nitrate salt and nitroaliphatics are compared with experimental data. Predicted melting points have average deviation of 5.4% for these energetic compounds. PMID:16839681

  16. Evidence for a plasma-membrane-bound nitrate reductase involved in nitrate uptake of Chlorella sorokiniana

    NASA Technical Reports Server (NTRS)

    Tischner, R.; Ward, M. R.; Huffaker, R. C.

    1989-01-01

    Anti-nitrate-reductase (NR) immunoglobulin-G (IgG) fragments inhibited nitrate uptake into Chlorella cells but had no affect on nitrate uptake. Intact anti-NR serum and preimmune IgG fragments had no affect on nitrate uptake. Membrane-associated NR was detected in plasma-membrane (PM) fractions isolated by aqueous two-phase partitioning. The PM-associated NR was not removed by sonicating PM vesicles in 500 mM NaCl and 1 mM ethylenediaminetetraacetic acid and represented up to 0.8% of the total Chlorella NR activity. The PM NR was solubilized by Triton X-100 and inactivated by Chlorella NR antiserum. Plasma-membrane NR was present in ammonium-grown Chlorella cells that completely lacked soluble NR activity. The subunit sizes of the PM and soluble NRs were 60 and 95 kDa, respectively, as determined by sodium-dodecyl-sulfate electrophoresis and western blotting.

  17. Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upwelling region

    SciTech Connect

    Blasco, D.; MacIsaac, J.J.; Packard, T.T.; Dugdale, R.C.

    1984-03-01

    Nitrate reductase (NR) activity and /sup 15/NO/sub 3//sup -/ uptake in phytoplankton were compared under different environmental conditions on two cruises in the upwelling region off Peru. The NR activity and NO/sub 3//sup -/ uptake rates responded differently to light and nutrients and the differences led to variations in the uptake: reductase ratio. Analysis of these variations suggests that the re-equilibration time of the two processes in response to environmental perturbation is an important source of variability. The nitrate uptake system responds faster than the nitrate reductase system. Considering these differences in response time the basic differences in the two processes, and the differences in their measurement, the authors conclude that the Nr activity measures the current nitrate-reducing potential, which reflects NO/sub 3//sup -/ assimilation before the sampling time, while /sup 15/NO/sub 3//sup -/ uptake measures NO/sub 3//sup -/ assimilation in the 6-h period following sampling.

  18. Surface-enhanced nitrate photolysis on ice.

    PubMed

    Marcotte, Guillaume; Marchand, Patrick; Pronovost, Stéphanie; Ayotte, Patrick; Laffon, Carine; Parent, Philippe

    2015-03-12

    Heterogeneous nitrate photolysis is the trigger for many chemical processes occurring in the polar boundary layer and is widely believed to occur in a quasi-liquid layer (QLL) at the surface of ice. The dipole-forbidden character of the electronic transition relevant to boundary layer atmospheric chemistry and the small photolysis/photoproduct yields in ice (and in water) may confer a significant enhancement and interfacial specificity to this important photochemical reaction at the surface of ice. Using amorphous solid water films at cryogenic temperatures as models for the disordered interstitial air-ice interface within the snowpack suppresses the diffusive uptake kinetics, thereby prolonging the residence time of nitrate anions at the surface of ice. This approach allows their slow heterogeneous photolysis kinetics to be studied, providing the first direct evidence that nitrates adsorbed onto the first molecular layer at the surface of ice are photolyzed more effectively than those dissolved within the bulk. Vibrational spectroscopy allows the ∼3-fold enhancement in photolysis rates to be correlated with the nitrates' distorted intramolecular geometry, thereby hinting at the role played by the greater chemical heterogeneity in their solvation environment at the surface of ice than that in the bulk. A simple 1D kinetic model suggests (1) that a 3(6)-fold enhancement in photolysis rate for nitrates adsorbed onto the ice surface could increase the photochemical NO2 emissions from a 5(8) nm thick photochemically active interfacial layer by 30(60)%, and (2) that 25(40)% of the NO2 photochemical emissions to the snowpack interstitial air are released from the topmost molecularly thin surface layer on ice. These findings may provide a new paradigm for heterogeneous (photo)chemistry at temperatures below those required for a QLL to form at the ice surface. PMID:25671500

  19. In situ biodenitrification of nitrate surface water

    SciTech Connect

    Schmidt, G.C.; Ballew, M.B.

    1995-12-31

    The US Department of Energy`s Weldon Spring Site Remedial Action Project has successfully operated a full-scale in situ biodenitrification system to treat water with elevated nitrate levels in abandoned raffinate pits. Bench- and pilot-scale studies were conducted to evaluate the feasibility of the process and to support its full-scale design and application. Bench testing evaluated variables that would influence development of an active denitrifying biological culture. The variables were carbon source, phosphate source, presence and absence of raffinate sludge, addition of a commercially available denitrifying microbial culture, and the use of a microbial growth medium. Nitrate levels were reduced from 750 mg/L NO{sub 3}-N to below 10 mg/L NO{sub 3}-N within 17 days. Pilot testing simulated the full-scale process to determine if nitrate levels could be reduced to less than 10 mg/L NO{sub 3}-N when high levels are present below the sludge surface. Four separate test systems were examined along with two control systems. Nitrates were reduced from 1,200 mg/L NO{sub 3}-N to below 2 mg/L NO{sub 3}-N within 21 days. Full-scale operation has been initiated to denitrify 900,000-gal batches alternating between two 1-acre ponds. The process used commercially available calcium acetate solution and monosodium/disodium phosphate solution as a nutrient source for indigenous microorganisms to convert nitrates to molecular nitrogen and water.

  20. Molten nitrate salt technology development status report

    SciTech Connect

    Carling, R.W.; Kramer, C.M.; Bradshaw, R.W.; Nissen, D.A.; Goods, S.H.; Mar, R.W.; Munford, J.W.; Karnowsky, M.M.; Biefeld, R.N.; Norem, N.J.

    1981-03-01

    Recognizing thermal energy storage as potentially critical to the successful commercialization of solar thermal power systems, the Department of Energy (DOE) has established a comprehensive and aggressive thermal energy storage technology development program. Of the fluids proposed for heat transfer and energy storage molten nitrate salts offer significant economic advantages. The nitrate salt of most interest is a binary mixture of NaNO/sub 3/ and KNO/sub 3/. Although nitrate/nitrite mixtures have been used for decades as heat transfer and heat treatment fluids the use has been at temperatures of about 450/sup 0/C and lower. In solar thermal power systems the salts will experience a temperature range of 350 to 600/sup 0/C. Because central receiver applications place more rigorous demands and higher temperatures on nitrate salts a comprehensive experimental program has been developed to examine what effects, if any, the new demands and temperatures have on the salts. The experiments include corrosion testing, environmental cracking of containment materials, and determinations of physical properties and decomposition mechanisms. This report details the work done at Sandia National Laboratories in each area listed. In addition, summaries of the experimental programs at Oak Ridge National Laboratory, the University of New York, EIC Laboratories, Inc., and the Norwegian Institute of Technology on molten nitrate salts are given. Also discussed is how the experimental programs will influence the near-term central receiver programs such as utility repowering/industrial retrofit and cogeneration. The report is designed to provide easy access to the latest information and data on molten NaNO/sub 3//KNO/sub 3/ for the designers and engineers of future central receiver projects.

  1. Menaquinol-nitrate oxidoreductase of Bacillus halodenitrificans.

    PubMed Central

    Ketchum, P A; Denariaz, G; LeGall, J; Payne, W J

    1991-01-01

    When grown anaerobically on nitrate-containing medium, Bacillus halodenitrificans exhibited a membrane-bound nitrate reductase (NR) that was solubilized by 2% Triton X-100 but not by 1% cholate or deoxycholate. Purification on columns of DE-52, hydroxylapatite, and Sephacryl S-300 yielded reduced methyl viologen NR (MVH-NR) with specific activities of 20 to 35 U/mg of protein that was stable when stored in 40% sucrose at -20 degrees C for 6 weeks. 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxypropone-1-sulfonat e (CHAPSO) and dodecyl-beta-D-maltoside stimulated enzyme activity three- to fourfold. Membrane extractions yielded purified NR that separated after electrophoresis into a 145-kDa alpha subunit, a 58-kDa beta subunit, and a 23-kDa gamma subunit. The electronic spectrum of dithionite-reduced, purified NR displayed peaks at 424.6, 527, and 557 nm, indicative of the presence of a cytochrome b, an interpretation consistent with the pyridine hemochrome spectrum formed. Analyses revealed a molybdenum-heme-non-heme iron ratio of 1:1:8 for the NR and the presence of molybdopterin. Electron paramagnetic resonance (EPR) signals characteristic of iron-sulfur centers were detected at low temperature. EPR also revealed a minor signal centered in the g = 2 region of the spectra. Upon reduction with dithionite, the enzyme displayed signals at g = 2.064, 2.026, 1.906, and 1.888, indicative of the presence of low-potential iron-sulfur centers, which resolve most probably as two [4Fe-4S]+1 clusters. With menadiol as the substrate for nitrate reduction, the Km for nitrate was 50-fold less than that seen when MVH was the electron donor. The cytochrome b557-containing enzyme from B. halodenitrificans is characterized as a menaquinol-nitrate:oxidoreductase. Images PMID:2013572

  2. Selective Nitrate Binding in Competitive Hydrogen Bonding Solvents: Do Anion–π Interactions Facilitate Nitrate Selectivity?**

    PubMed Central

    Watt, Michelle M.; Zakharov, Lev N.

    2013-01-01

    New tripodal urea receptors demonstrate preferential binding of anions over competitive hydrogen bonding solvents. 1H NMR titrations in 10% DMSO-d6/CDCl3 show a higher affinity for nitrate over the halides for the fluorinated receptor, which is lost when the fluorines are removed. An “anion–π” interaction between the nitrate and the π-system of the ethynyl-substituted arene is proposed as the source of this selectivity. PMID:23939999

  3. Synthesis and Characterization of Zirconium Tungstate Ultra-Thin Fibers

    SciTech Connect

    Zhang, Lifeng; Howe, Jane Y; Fong, Hao; Zhang, Yan

    2009-01-01

    This study reports an innovative method of electrospinning followed by pyrolysis to synthesize zirconium tungstate (ZrW2O8), a material with negative coefficient of thermal expansion (CTE), in ultra-thin fiber form. Morphologies and microstructures of the as-electrospun precursor fibers, the heat-treated intermediate fibers, and the final ZrW2O8 ultra-thin fibers were characterized by SEM, XRD, and TEM. The ZrW2O8 ultra-thin fibers had diameters in the sub-micrometer range with aspect ratios larger than 100; these fibers were polycrystalline, and consisted of single crystalline ZrW2O8 crystallites with sizes of 30-50 nm and surface roughness of several nanometers. The ZrW2O8 ultra-thin fibers are expected to outperform spherically, cylindrically, and/or irregularly shaped polycrystalline ZrW2O8 particles for the development of composites with precisely controlled CTEs. Additionally, this reported method could be utilized as a general approach to convert nano-scaled inorganic particles into fibers.

  4. The first step for delayed hydride cracking in zirconium alloys

    NASA Astrophysics Data System (ADS)

    McRae, G. A.; Coleman, C. E.; Leitch, B. W.

    2010-01-01

    Two models for delayed hydride cracking (DHC) in zirconium alloys are distinguished by their first step: The loading of a crack induces hydride precipitation. The hydride is postulated to create a hydrogen concentration gradient, where the bulk concentration is greater than that at the crack tip. This concentration gradient is taken as the driving force for diffusion of hydrogen to the crack tip, and subsequent hydride growth. This model is called the precipitate first model (PFM). The tensile stress at the crack tip induces a gradient in chemical potential that promotes the diffusion of hydrogen to the crack tip. Hydrides form if the hydrogen concentration reaches the solubility limit for hydride precipitation. The mechanism is postulated to create a hydrogen concentration gradient, where the bulk concentration is lower than that at the crack tip. The gradient in chemical potential is taken as the driving force for diffusion of hydrogen to the crack tip, and subsequent hydride growth. This model is called the diffusion first model (DFM). The second model, DFM, is developed. This model is shown to describe the main features of the experimental observations of DHC, without invoking new phenomena, such as reduction in the solubility limit for precipitation of hydride, as required by the PFM.

  5. Mitigation of harmful effects of welds in zirconium alloy components

    SciTech Connect

    Coleman, C.E.; Doubt, G.L.; Fong, R.W.L.; Root, J.H.; Bowden, J.W.; Sagat, S.; Webster, R.T.

    1994-12-31

    Welding produces local residual tensile stresses and changes in texture in components made from zirconium alloys. In the heat-affected zone in tubes or plates, the basal plane normals are rotated into the plane of the component and perpendicular to the direction of the weld. Thin-walled Zircaloy-2 tubes containing an axial weld do not reach their full strength because they always fail prematurely in the weld when pressurized to failure in a fixed-end burst test. Reinforcing the weld by increasing its thickness by 25% moves the failure to the parent metal and improves the biaxial strength of the tube by 20 to 25% and increases the total elongation by 200 to 450%. In components made from Zr-2.5Nb, the texture in the heat-affected zone promotes delayed hydride cracking (DHC) driven by tensile residual stress. Although the texture is not much affected by heat-treatments below 630 C and large grain interaction stresses remain as a result of mixed textures, macro-residual tensile stresses can be relieved by heat treatment to the point where the probability of cracking is very low.

  6. The thermophysical properties of calcium and barium zirconium phosphate

    NASA Astrophysics Data System (ADS)

    Gregg, Daniel J.; Karatchevtseva, Inna; Triani, Gerry; Lumpkin, Gregory R.; Vance, Eric R.

    2013-10-01

    The thermophysical and structural properties of calcium and barium zirconium phosphate ceramics (CZP and BZP) have been investigated for their potential candidacy as actinide hosts for inert matrix fuels (IMF) in nuclear reactors. These phosphate ceramics, which can accommodate minor actinides as well as the resulting fission products, are found to be thermally stable to 1600 °C in air, however they begin to decompose in an inert atmosphere above approximately 1400 °C. The heat capacity, thermal conductivity and bulk thermal-expansion were measured from room temperature up to 1200 °C. Structural changes in this temperature region as well as the anisotropic thermal-expansion behaviour were studied using high-temperature X-ray diffraction. A phase change from R-3 to R-3c was identified for Ba0.5Zr2(PO4)3 near 880 °C. The thermal conductivity for these ceramics at 1000 °C was found to be 1.0 W m-1 K-1, a relatively low thermal conductivity that was increased to 5.0 W m-1 K-1 at 1000 °C for BZP:Ni (25:75 mass ratio) cermet composites.

  7. Mesoporous Zirconium Phenylenesiliconate-phosphonate Hybrids with Ordered Lamellar Nanostructures.

    PubMed

    Maeda, Kazuyuki; Kobayashi, Hiroki; Oguro, Kaku; Otsu, Masato; Kondo, Atsushi; Maki, Tei

    2015-11-16

    Novel ordered lamellar mesostructure pZrPS-2 was hydrothermally prepared by using zirconium propoxide and 4-(EtO)2OPC6H4Si(OEt)3 (pPPS-E), which was hydrolyzed to organic building units substituted with both siliconate and phosphonate groups, in the presence of Cn TAB and TMAOH. The pZrPS-2 materials were obtained at a Zr/PPS ratio of 2 or higher and the basal spacing was increased by using a longer-chain surfactant (n = 12-18). Removal of the occluded surfactants at 300 °C resulted in retention of the lamellar structure with negligible shrinkage of the interlayer distance. Nitrogen adsorption studies revealed the ordered mesoporous nature of pZrPS-2 with a pore diameter of approximately 2 to 3 nm. The lamellar structure is assumed to be composed of layers that include zirconia-based crystalline nanodomains and interlayer pillars mainly based on PPS units. Although lamellar structures with the same crystalline phase also formed when no surfactant was added or when the meta isomer of PPS was used, no mesoporous materials were obtained except pZrPS-2. A possible schematic model to elucidate these results is also proposed. PMID:26427615

  8. Damage production and recovery in zirconium irradiated with fusion neutrons

    NASA Astrophysics Data System (ADS)

    Guinan, M. W.; Zee, R. H.

    1984-05-01

    High purity zirconium was irradiated at 4.2 K to a dose of 1.8 × 10 21 n/m 2 at the Livermore Rotating Target Neutron Source (RTNS-II). The resistivity of the wire was measured during irradiation at dose increments of 1.2 × 10 19 n/m providing a detailed damage rate history. Following irradiation, isochronal annealing was performed up to 340 K. The results of the damage rate study reveal a pronounced concave (positive) curvature in a plot of dΔρ/dφt versus Δρ. By linearly extrapolating the last third of the damage-rate curve, a value of 100 nΩ-m was obtained as a lower limit for the actual saturation resistivity. Comparing the initial damage rate of this work to that of a similar study using a pure fission spectrum, we found that our rate was 30% lower than expected on a damage energy basis. This difference is considerably larger than that of 8 cubic metals (Al, V, Ni, Cu, Nb, Mo, W and Pt) for which damage energy scaling from fission results were accurate to within 10%. Two annealing peaks, at 116 K and 245 K, were found in the post-irradiation annealing study. Both the positions and the relative peak heights are in agreement with earlier work using fission neutrons.

  9. Gadolinium-hydrogen ion exchange of zirconium phosphate

    NASA Technical Reports Server (NTRS)

    Liu, D. C.; Power, J. L.

    1972-01-01

    The Gd(+3)/H(+) ion exchange on a commercial zirconium phosphate ion exchanger was investigated in chloride, sulfate, and phosphate solutions of Gd(+3) at gadolinium concentrations of 0.001 to 1 millimole per cc and in the pH range of 0 to 3.5. Relatively low Gd(+3) capacities, in the range of 0.01 to 0.1 millimole per g of ion exchanger were found at room temperature. A significant difference in Gd(+3) sorption was observed, depending on whether the ion exchanger was converted from initial conditions of greater or lesser Gd(+3) sorption than the specific final conditions. Correlations were found between decrease in Gd(+3) capacity and loss of exchanger phosphate groups due to hydrolysis during washing and between increase in capacity and treatment with H3PO4. Fitting of the experimental data to ideal ion exchange equilibrium expressions indicated that each Gd(+3) ion is sorbed on only one site of the ion exchanger. The selectivity quotient was determined to be 2.5 + or - 0.4 at room temperature on gadolinium desorption in chloride solutions.

  10. Biologically functionalized nanochannels on ferroelectric lead zirconium titanate surfaces.

    SciTech Connect

    Ocola, L. E.; Pan, W. C.; Kuo, M.; Tirumala, V. R.; Reiss, B. D.; Firestone, M. A.; Illinois Mathematics and Science Academy

    2005-01-01

    We recently started a program at Argonne to exploit patterned, polarizable ferroelectric surfaces, such as lead zirconium titanate (PZT), as a means to create field-responsive inorganic-biomolecule interfaces to study and manipulate biomatter on surfaces. In this paper we will discuss the integration of nanochannels on the surface of PZT films and their selective functionalization to create nanovalves to control nanofluidic flow. Microfluidic devices have been fabricated using a variety of methods, ranging from thermal decomposition of buried patterned channels, to fabricating trenches via plasma etch or hot embossing followed by trench capping. Our work focuses on an alternative method by using a bilayer resist in an inverted configuration normally used for T- and Gamma- gate fabrication. This method is capable of yielding sub-100 nm nanochannels with high aspect ratios and sub-500nm alignment. We have recently demonstrated that the polarization hysteresis loop of PZT is the same before and after exposure to an aqueous environment. This opens the possibility of selective surface modification of PZT via coupling of a wide range of biomolecules (e.g., peptides, proteins) and the use of the electric-field-responsive properties of PZT to manipulate the function (e.g., orientation) of the tethered biomolecules. We have used phage display techniques to evolve specific peptide motifs that selectively bind to PZT. The optimum heptapeptide that facilitates both the attachment of functional biological molecules to the surface of PZT has been identified.

  11. Surface, structural and tensile properties of proton beam irradiated zirconium

    NASA Astrophysics Data System (ADS)

    Rafique, Mohsin; Chae, San; Kim, Yong-Soo

    2016-02-01

    This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

  12. High-rate reactive sputter deposition of zirconium dioxide

    SciTech Connect

    Jones, F.

    1988-11-01

    Using an improved reactive sputter deposition technique, zirconium dioxide is deposited on cooled and uncooled substrates at low, medium, and high rates of 51.7, 95.4, and 152.4 nm/min, respectively. The films are deposited by sputtering a Zr target in an oxygen--argon plasma. The Zr target remains in the metallic state. The films are characterized by measuring the stoichiometry, refractive index, optical transmission, stress, and crystallinity as a function of deposition rate. Films deposited on (100) N-type silicon substrates were annealed at temperatures ranging from 200 to 500 /sup 0/C in steps of 50 /sup 0/C. X-ray diffraction patterns show that the ''as-deposited'' films contain polycrystalline and amorphous phases of various amounts depending on the deposition rate and substrate temperature. Amorphous components crystallize into the cubic phase as the annealing temperature increases. At deposition rates of 95.4 and 152.4 nm/min, the refractive index and optical transmission (at 820 nm)= of the unannealed, as-deposited films are not affected by the quantity of material in the amorphous state and are also independent of substrate temperature.

  13. Strain effects on oxygen transport in tetragonal zirconium dioxide

    SciTech Connect

    Xian-Ming Bai; Yongfeng Zhang; Michael R. Tonks

    2013-11-01

    Temperature accelerated dynamics and molecular dynamics simulations are used to investigate the strain effects on oxygen interstitial and vacancy migration in tetragonal zirconium dioxide. At zero external strain, the anisotropic migration mechanisms of oxygen defects are characterized. At non-zero strains, both the crystal structure and defect migration barriers are modified by strain. Under compressive strains, the defect migration barrier increases with the increasing strain for both interstitials and vacancies. The crystal structure transforms from a tetragonal to a nearly cubic fluorite structure. Accordingly, the defect migration becomes nearly isotropic. Under dilative strains, the migration barrier first decreases then increases with increasing strain for both types of defects. The tetragonal phase transforms to a lower symmetry structure that is close to the orthorhombic phase. In turn, the defect migration becomes highly anisotropic. Under both compressive and dilative strains, interstitials respond to strain more strongly than vacancies. At small dilative strains, an oxygen interstitial has comparable diffusivity to a vacancy, suggesting that both types of defects can contribute to oxygen transport, if they are present. Although currently no previous result is available to validate oxygen interstitial diffusion behavior, the trend of strain effects on oxygen vacancy diffusion is in good agreement with available experimental and theoretical studies in the literature.

  14. SURFACE MODIFICATION OF ZIRCALOY-4 SUBSTRATES WITH NICKEL ZIRCONIUM INTERMETALLICS

    SciTech Connect

    Luscher, Walter G.; Gilbert, Edgar R.; Pitman, Stan G.; Love, Edward F.

    2013-02-01

    Surfaces of Zircaloy-4 (Zr-4) substrates were modified with nickel-zirconium (NiZr) intermetallics to tailor oxidation performance for specialized applications. Surface modification was achieved by electroplating Zr-4 substrates with nickel (Ni) and then performing thermal treatments to fully react the Ni plating with the substrates, which resulted in a coating of NiZr intermetallics on the substrate surfaces. Both plating thickness and thermal treatment were evaluated to determine the effects of these fabrication parameters on oxidation performance and to identify an optimal surface modification process. Isothermal oxidation tests were performed on surface-modified materials at 290°, 330°, and 370°C under a constant partial pressure of oxidant (i.e., 1 kPa D2O in dry Ar at 101 kPa) for 64 days. Test results revealed an enhanced, transient oxidation rate that decreased asymptotically toward the rate of the Zr-4 substrate. Oxidation kinetics were analyzed from isothermal weight gain data, which were correlated with microstructure, hydrogen pickup, strength, and hardness.

  15. Structural evolution of zirconium carbide under ion irradiation

    NASA Astrophysics Data System (ADS)

    Gosset, D.; Doll, M.; Simeone, D.; Baldinozzi, G.; Thom, L.

    2008-02-01

    Zirconium carbide is one of the candidate materials to be used for some fuel components of the high temperature nuclear reactors planned in the frame of the Gen-IV project. Few data exist regarding its behaviour under irradiation. We have irradiated ZrC samples at room temperature with slow heavy ions (4 MeV Au, fluence from 10 11 to 5 10 15 cm -2) in order to simulate neutron irradiations. Grazing incidence X-Ray diffraction (GIXRD) and transmission electron microscopy (TEM) analysis have been performed in order to study the microstructural evolution of the material versus ion fluence. A high sensitivity to oxidation is observed with the formation of zirconia precipitates during the ion irradiations. Three damage stages are observed. At low fluence (<10 12 cm -2), low modifications are observed. At intermediate fluence, high micro-strains appear together with small faulted dislocation loops. At the highest fluence (>10 14 cm -2), the micro-strains saturate and the loops coalesce to form a dense dislocation network. No other structural modification is observed. The material shows a moderate cell parameter increase, corresponding to a 0.6 vol.% swelling, which saturates around 10 14 ions/cm 2, i.e., a few Zr dpa. As a result, in spite of a strong covalent bonding component, ZrC seems to have a behaviour under irradiation close to cubic metals.

  16. Characterization of precipitates in a niobium-zirconium-carbon alloy

    NASA Technical Reports Server (NTRS)

    Grobstein, T. L.; Titran, R. H.

    1986-01-01

    A niobium alloy with 1 percent zirconium and 0.063 percent carbon by weight was investigated in the as-rolled and annealed conditions, and after high-temperature (1350 and 1400 K) exposure with and without an applied stress. In the as-rolled and annealed conditions, large metastable carbides were observed in addition to a regular distribution of small particles. During the high-temperature exposure, the majority of the large carbides were dissolved and a more stable carbide phase formed. This finely dispersed phase had a composition determined to be approximately 70 percent ZrC and approximately 30 percent NbC and showed some evidence of an orientation relationship with the matrix. The precipitates appeared to coarsen slightly after approximately 5000 hr exposure in the presence of an applied stress resulted in a decrease in the size and in the interparticle spacing of the stable precipitates. However, the composition of the precipitate phase and its ability to pin dislocations were not affected by the temperature or stress conditions.

  17. Kinetics of α to ω structural transition in zirconium

    NASA Astrophysics Data System (ADS)

    Velisavljevic, Nenad; Jacobsen, Matthew; Sinogeikin, Stanislav; Popov, Dmitry

    2015-06-01

    Zirconium (Zr), along with the other group IV-B transition metals titanium (Ti) and hafnium (Hf), has been widely investigated at high P-T conditions. Initial interest in Zr may have been driven in part by need to understand structural stability at conditions that these materials could experience in a wide range of commercial applications. Multiple studies demonstrate that, at elevated pressure, these metals and their alloys undergo a structural transition from hexagonal close-packed (α) phase to another hexagonal (ω) phase. Subsequently, α- ω transition has been investigated in detail - results indicate that the α- ω boundary is significantly influenced by sample purity, experimental conditions (e.g. hydrostatic vs. uniaxial compression), loading conditions (e.g. shock vs. slower ``static'' loading), etc. Early measurements also indicate that kinetics at the onset of α- ω transition may play a significant role in establishing the phase boundary and thus must be fully investigated to gain a more comprehensive understanding of behavior of Zr at high P-T. Ongoing advances in large scale x-ray sources and detector and instrumentation technologies have made investigations of transition kinetics over broader P-T and compression/strain rate conditions possible. Using DAC coupled with piezoelectric and/or gas membrane loading, α- ω transition in Zr was investigated as a function of compression (P-jump) rate. Relevant results, as well as broader impacts regarding α- ω transition mechanism, will be presented.

  18. Structural study of the dehydration of templated zirconium phosphate fluorides

    NASA Astrophysics Data System (ADS)

    Wloka, Martin; Troyanov, Sergey; Kemnitz, Erhard

    2002-11-01

    The zirconium phosphate fluorides with the general formula [AmH x] 1/ x[Zr 2(PO 4) 2(HPO 4)F]· nH 2O with Am= N-methylethylenediamine, 1,3-diaminopropane and N, N-dimethylethylenediamine consist of a three-dimensional framework (designated as ZrPOF-1). Channels are made up of eight-membered rings of Zr-octahedra and phosphate tetrahedra running through the framework structure. Water molecules are located in small cavities and also are often located in the channels together with the organic template cation. Single crystal structure investigation of the carefully dehydrated phases shows that during the dehydration process hydrogen bridges are broken and new ones are formed. The loss of water results in a rearrangement of the hydrogen phosphate groups and in a relative shift of compact sheets connected via the HPO 4 tetrahedra in the framework structure. The structural consequences of the dehydration of these three ZrPOF-1 phases were discussed in detail.

  19. Extraction of nitric acid, uranyl nitrate, and bismuth nitrate from aqueous nitric acid solutions with CMPO

    SciTech Connect

    Spencer, B.B.

    1995-08-01

    DOE sponsored development of the transuranium extraction (TRUEX) process for removing actinides from radioactive wastes. The solvent is a mixture of CMPO and TBP. Since the extraction characteristics of CMPO are not as well understood as those of TBP, the extraction of nitric acid, uranyl nitrate, and bismuth nitrate with CMPO (dissolved in n-dodecane) were studied. Results indicate that CMPO extracts nitric acid with a 1:1 stoichiometry; equilibrium constant is 2. 660{plus_minus}0.092 at 25 C, and extraction enthalpy is -5. 46{plus_minus}0.46 kcal/mol. Slope analysis indicates that uranyl nitrate extracts with a mixed equilibria of 1:1 and 2:1 stoichiometries in nearly equal proportion. Equil. constant of the 2: 1 extraction was 1.213 {times} 10{sup 6}{plus_minus}3.56 {times} 10{sup 4} at 25 C; reaction enthalpy was -9.610{plus_minus}0.594 kcal/mol. Nitration complexation constant is 8.412{plus_minus}0.579, with an enthalpy of -10.72{plus_minus}1.87 kcal/mol. Bismuth nitrate also extracts with a mixed equilibria of (perhaps) 1:1 and 2:1 stoichiometries. A 2:1 extraction equilibrium and a nitrate complexation adequately model the data. Kinetics and enthalpies were also measured.

  20. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  1. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  2. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  3. 40 CFR 721.7500 - Nitrate polyether polyol (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nitrate polyether polyol (generic name... Substances § 721.7500 Nitrate polyether polyol (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nitrate polyether polyol (PMN P88-2540)...

  4. 9 CFR 319.2 - Products and nitrates and nitrites.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Products and nitrates and nitrites... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a standard in this part and to which nitrate or nitrite is permitted or required to be added, may be...

  5. 9 CFR 319.2 - Products and nitrates and nitrites.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Products and nitrates and nitrites... and nitrates and nitrites. Any product, such as frankfurters and corned beef, for which there is a standard in this part and to which nitrate or nitrite is permitted or required to be added, may be...

  6. 40 CFR 721.7500 - Nitrate polyether polyol (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nitrate polyether polyol (generic name... Substances § 721.7500 Nitrate polyether polyol (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nitrate polyether polyol (PMN P88-2540)...

  7. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  8. FLAME DENITRATION AND REDUCTION OF URANIUM NITRATE TO URANIUM DIOXIDE

    DOEpatents

    Hedley, W.H.; Roehrs, R.J.; Henderson, C.M.

    1962-06-26

    A process is given for converting uranyl nitrate solution to uranium dioxide. The process comprises spraying fine droplets of aqueous uranyl nitrate solution into a hightemperature hydrocarbon flame, said flame being deficient in oxygen approximately 30%, retaining the feed in the flame for a sufficient length of time to reduce the nitrate to the dioxide, and recovering uranium dioxide. (AEC)

  9. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a..., packaging, transporting, or holding food, subject to the provisions of this section. (a) Sodium...

  10. [Nitrates and nitrites in plant tissues. Analytical methods].

    PubMed

    Brugel, P

    1980-01-01

    Different methods for nitrites and nitrates determination are described. Each step is considered separately, extraction, purification, determination of nitrate. During the last step, we examine the different analytical possibilities. Expecting for electrochemical methods, especially polarography, give satisfaction, the retained methods is that used as reference method for nitrate determination in meat and meat based products: Norme Afnor V04 - 409 et 410. PMID:7258914

  11. Nitrate Inhibition of Legume Nodule Growth and Activity 1

    PubMed Central

    Streeter, John G.

    1985-01-01

    Soybean plants (Glycine max [L.] Merr) were grown in sand culture with 2 millimolar nitrate for 37 days and then supplied with 15 millimolar nitrate for 7 days. Control plants received 2 millimolar nitrate and 13 millimolar chloride and, after the 7-day treatment period, all plants were supplied with nil nitrate. The temporary treatment with high nitrate inhibited nitrogenase (acetylene reduction) activity by 80% whether or not Rhizobium japonicum bacteroids had nitrate reductase (NR) activity. The pattern of nitrite accumulation in nodules formed by NR+ rhizobia was inversely related to the decrease and recovery of nitrogenase activity. However, nitrite concentration in nodules formed by NR− rhizobia appeared to be too low to explain the inhibition of nitrogenase. Carbohydrate composition was similar in control nodules and nodules receiving 15 millimolar nitrate suggesting that the inhibition of nitrogenase by nitrate was not related to the availability of carbohydrate. Nodules on plants treated with 15 millimolar nitrate contained higher concentrations of amino N and, especially, ureide N than control nodules and, after withdrawal of nitrate, reduced N content of treated and control nodules returned to similar levels. The accumulation of N2 fixation products in nodules in response to high nitrate treatment was observed with three R. japonicum strains, two NR+ and one NR−. The high nitrate treatment did not affect the allantoate/allantoin ratio or the proportion of amino N or ureide N in bacteroids (4%) and cytosol (96%). PMID:16664052

  12. THE CONTROL OF NITRATE AS A WATER POLLUTANT

    EPA Science Inventory

    This study was based on the premise that the most logical approach to reducing nitrate leaching in soils was to limit the amount of nitrate in the soil solution at any one time. Methods of limiting the concentration of nitrate in the soil solution while maintaining an adequate su...

  13. Disposable nitrate-selective optical sensor based on fluorescent dye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, disposable thin-film optical nitrate sensor was developed. The sensor was fabricated by applying a nitrate-selective polymer membrane on the surface of a thin polyester film. The membrane was composed of polyvinylchloride (PVC), plasticizer, fluorescent dye, and nitrate-selective ionophore...

  14. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  15. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  16. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  17. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  18. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  19. Phosphate adsorption from wastewater using zirconium (IV) hydroxide: Kinetics, thermodynamics and membrane filtration adsorption hybrid system studies.

    PubMed

    Johir, M A H; Pradhan, M; Loganathan, P; Kandasamy, J; Vigneswaran, S

    2016-02-01

    Excessive phosphate in wastewater should be removed to control eutrophication of water bodies. The potential of employing amorphous zirconium (Zr) hydroxide to remove phosphate from synthetic wastewater was studied in batch adsorption experiments and in a submerged membrane filtration adsorption hybrid (MFAH) reactor. The adsorption data satisfactorily fitted to Langmuir, pseudo-first order and pseudo-second order models. Langmuir adsorption maxima at 22 °C and pHs of 4.0, 7.1, and 10.0 were 30.40, 18.50, and 19.60 mg P/g, respectively. At pH 7.1 and temperatures of 40 °C and 60 °C, they were 43.80 and 54.60 mg P/g, respectively. The thermodynamic parameters, ΔG° and ΔS° were negative and ΔH° was positive. FTIR, zeta potential and competitive phosphate, sulphate and nitrate adsorption data showed that the mechanism of phosphate adsorption was inner-sphere complexation. In the submerged MFAH reactor experiment, when Zr hydroxide was added at doses of 1-5 g/L once only at the start of the experiment, the removal of phosphate from 3 L of wastewater containing 10 mg P/L declined after 5 h of operation. However, when Zr hydroxide was repeatedly added at 5 g/L dose every 24 h, satisfactory removal of phosphate was maintained for 3 days. PMID:26686069

  20. Anisole Nitration During Gamma-Irradiation of Aqueous Nitrite and Nitrate Solutions: Free Radical Versus Ionic Mechanisms

    SciTech Connect

    Gracy Elias; Bruce J. Mincher; Leigh R. Martin; Stephen P. Mezyk; Thomas D. Cullen

    2010-04-01

    The nitration of aromatic compounds in the condensed phase is of interest to nuclear waste treatment applications. This chapter discusses our investigation of radiolytic aromatic nitration mechanisms in the condensed phase toward understanding the nitration products created during nuclear fuel reprocessing. The nitration reactions of anisole, a model aromatic compound, were studied in ?-irradiated acidic nitrate, neutral nitrate, and neutral nitrite solutions. The nitrated anisole product distributions were the same with and without radiation in acidic solution, although more products were formed with radiation. In the irradiated acidic condensed phase, radiation-enhanced nitrous acid-catalyzed nitrosonium ion electrophilic aromatic substitution followed by oxidation reactions dominated over radical addition reactions. Neutral nitrate anisole solutions were dominated by mixed nitrosonium/nitronium ion electrophilic aromatic substitution reactions, but with lower product yields. Irradiation of neutral nitrite anisole solution resulted in a statistical substitution pattern for nitroanisole products, suggesting non-electrophilic free radical reactions involving the •NO2 radical.

  1. The nitrate time bomb: a numerical way to investigate nitrate storage and lag time in the unsaturated zone.

    PubMed

    Wang, L; Butcher, A S; Stuart, M E; Gooddy, D C; Bloomfield, J P

    2013-10-01

    Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the 'store' of nitrate and its potentially long travel time in the unsaturated and saturated zones. However, this time lag is rarely considered in current water nitrate management and policy development. The aim of this study was to develop a catchment-scale integrated numerical method to investigate the nitrate lag time in the groundwater system, and the Eden Valley, UK, was selected as a case study area. The method involves three models, namely the nitrate time bomb-a process-based model to simulate the nitrate transport in the unsaturated zone (USZ), GISGroundwater--a GISGroundwater flow model, and N-FM--a model to simulate the nitrate transport in the saturated zone. This study answers the scientific questions of when the nitrate currently in the groundwater was loaded into the unsaturated zones and eventually reached the water table; is the rising groundwater nitrate concentration in the study area caused by historic nitrate load; what caused the uneven distribution of groundwater nitrate concentration in the study area; and whether the historic peak nitrate loading has reached the water table in the area. The groundwater nitrate in the area was mainly from the 1980s to 2000s, whilst the groundwater nitrate in most of the source protection zones leached into the system during 1940s-1970s; the large and spatially variable thickness of the USZ is one of the major reasons for unevenly distributed groundwater nitrate concentrations in the study area; the peak nitrate loading around 1983 has affected most of the study area. For areas around the Bowscar, Beacon Edge, Low Plains, Nord Vue, Dale Springs, Gamblesby, Bankwood Springs, and Cliburn, the peak nitrate loading will arrive at the water table in the next 34 years; statistical analysis shows that 8.7 % of the Penrith Sandstone and 7.3 % of the St Bees Sandstone have not been affected by peak nitrate. This research can improve the scientific understanding of nitrate processes in the groundwater system and support the effective management of groundwater nitrate pollution for the study area. With a limited number of parameters, the method and models developed in this study are readily transferable to other areas. PMID:23801341

  2. Synthesis of zirconium tungstate-zirconia core-shell composite particles

    SciTech Connect

    Khazeni, Nasser; Mavis, Bora; Guenduez, Guengoer; Colak, Uner

    2011-11-15

    Highlights: {yields} ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell particles to offer solutions for sintering problems. {yields} Core synthesis by a precursor based on tungstic acid and zirconium acetate. {yields} Shell phase by urea hydrolysis in the presence of zirconium ions. {yields} [Urea]/[ZrOCl{sub 2}] ratio controls the rate of shell precursor precipitation. -- Abstract: In this work, ZrW{sub 2}O{sub 8}-ZrO{sub 2} core-shell composite particles were synthesized. ZrW{sub 2}O{sub 8} that was used in the core is a material with negative coefficient of thermal expansion, and it was synthesized from a high-pH precursor based on use of tungstic acid and zirconium acetate. Shell layer was composed of ZrO{sub 2} nanocrystallites and precipitated from an aqueous solution by urea hydrolysis. While volume of the shell was effectively controlled by the initial zirconium ion concentration in the solutions, the rate of precipitation was a function of the ratio of initial concentrations of urea to zirconium ions. It is hypothesized that isolation of the ZrW{sub 2}O{sub 8} within a layer of ZrO{sub 2}, will be a key element in solving problems associated with reactivity of ZrW{sub 2}O{sub 8} towards other components in sintering of ceramic-ceramic composites with tuned or zero thermal expansion coefficient.

  3. A comparative study of zirconium and titanium implants in rat: osseointegration and bone material quality.

    PubMed

    Hoerth, Rebecca M; Katunar, María R; Gomez Sanchez, Andrea; Orellano, Juan C; Ceré, Silvia M; Wagermaier, Wolfgang; Ballarre, Josefina

    2014-02-01

    Permanent metal implants are widely used in human medical treatments and orthopedics, for example as hip joint replacements. They are commonly made of titanium alloys and beyond the optimization of this established material, it is also essential to explore alternative implant materials in view of improved osseointegration. The aim of our study was to characterize the implant performance of zirconium in comparison to titanium implants. Zirconium implants have been characterized in a previous study concerning material properties and surface characteristics in vitro, such as oxide layer thickness and surface roughness. In the present study, we compare bone material quality around zirconium and titanium implants in terms of osseointegration and therefore characterized bone material properties in a rat model using a multi-method approach. We used light and electron microscopy, micro Raman spectroscopy, micro X-ray fluorescence and X-ray scattering techniques to investigate the osseointegration in terms of compositional and structural properties of the newly formed bone. Regarding the mineralization level, the mineral composition, and the alignment and order of the mineral particles, our results show that the maturity of the newly formed bone after 8 weeks of implantation is already very high. In conclusion, the bone material quality obtained for zirconium implants is at least as good as for titanium. It seems that the zirconium implants can be a good candidate for using as permanent metal prosthesis for orthopedic treatments. PMID:24170339

  4. Zirconium-based alloys, nuclear fuel rods and nuclear reactors including such alloys, and related methods

    DOEpatents

    Mariani, Robert Dominick

    2014-09-09

    Zirconium-based metal alloy compositions comprise zirconium, a first additive in which the permeability of hydrogen decreases with increasing temperatures at least over a temperature range extending from 350.degree. C. to 750.degree. C., and a second additive having a solubility in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. At least one of a solubility of the first additive in the second additive over the temperature range extending from 350.degree. C. to 750.degree. C. and a solubility of the second additive in the first additive over the temperature range extending from 350.degree. C. to 750.degree. C. is higher than the solubility of the second additive in zirconium over the temperature range extending from 350.degree. C. to 750.degree. C. Nuclear fuel rods include a cladding material comprising such metal alloy compositions, and nuclear reactors include such fuel rods. Methods are used to fabricate such zirconium-based metal alloy compositions.

  5. Hopping conduction in zirconium oxynitrides thin film deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Guo, Jie; Zhan, Guanghui; Liu, Jingquan; Yang, Bin; Xu, Bin; Feng, Jie; Chen, Xiang; Yang, Chunsheng

    2015-10-01

    Zirconium oxynitrides thin film thermometers were demonstrated to be useful temperature sensors. However, the basic conduction mechanism of zirconium oxynitrides films has been a long-standing issue, which hinders the prediction and optimization of their ultimate performance. In this letter, zirconium oxynitrides films were grown on sapphire substrates by magnetron sputtering and their electric transport mechanism has been systemically investigated. It was found that in high temperatures region (>150 K) the electrical conductivity was dominated by thermal activation for all samples. In the low temperatures range, while Mott variable hopping conduction (VRH) was dominated the transport for films with relatively low resistance, a crossover from Mott VRH conduction to Efros-Shklovskii (ES) VRH was observed for films with relatively high resistance. This low temperature crossover from Mott to ES VRH indicates the presence of a Coulomb gap (~7 meV). These results demonstrate the competing and tunable conduction mechanism in zirconium oxynitrides thin films, which would be helpful for optimizing the performance of zirconium oxynitrides thermometer.

  6. Increased force simulator wear testing of a zirconium oxide total knee arthroplasty.

    PubMed

    Lee, Joshua K L; Maruthainar, Kunalan; Wardle, Nic; Haddad, Fares; Blunn, Gordon W

    2009-08-01

    Total knee replacements provide cost effective treatment for debilitating conditions such as osteoarthritis. Their long term performance is governed by ultra-high molecular weight polyethylene (UHMWPE) wear which produces wear debris leading to osteolysis and aseptic loosening of the implant. An oxidised zirconium alternative to cobalt chrome is being used to reduce wear debris formation in the younger patients. Two TKRs of cobalt chrome and two of zirconium oxide coated zirconium were tested in a six degrees of freedom of motion, Stanmore-Instron force controlled knee wear simulator over 4 million increased force cycles. Oxidised zirconium was demonstrated to be more scratch resistant than CoCr. Increases in Ra (mean average roughness) of 12-fold compared to 1.9 fold rise for ZrO. The differences in roughness were accompanied by a 78%, statistically significant, reduction in wear of UHMWPE with the ZrO femoral components compared to the CoCr (p=0.037). Long term clinical results from the use of oxidised zirconium femoral components are awaited. However, it shows potential to reduce the wear rate. PMID:19321347

  7. Discrepancy between nitrate reduction rates in intact leaves and nitrate reductase activity in leaf extracts: what limits nitrate reduction in situ?

    PubMed

    Kaiser, W M; Kandlbinder, A; Stoimenova, M; Glaab, J

    2000-04-01

    Nitrate reductase (NR) activity in spinach leaf extracts prepared in the presence of a protein phosphatase inhibitor (50 microM cantharidine) was measured in the presence of Mg2+ (NRact) or EDTA (NRmax), under substrate saturation. These in-vitro activities were compared with nitrate reduction rates in leaves from nitrate-sufficient plants. Spinach leaves containing up to 60 micromol nitrate per g fresh weight were illuminated in air with their petiole in water. Their nitrate content decreased with time, permitting an estimation of nitrate reduction in situ. The initial rates (1-2 h) of nitrate consumption were usually lower than NRact, and with longer illumination time (4 h) the discrepancy grew even larger. When leaves were fed through their petiole with 30 mM nitrate, initial in-situ reduction rates calculated from nitrate uptake and consumption were still lower than NRact. However, nitrate feeding through the petiole maintained the in situ-nitrate reduction rate for a longer time. Initial rates of nitrate reduction in situ only matched NRact when leaves were illuminated in 5% CO2. In CO2-free air or in the dark, both NRact and in-situ nitrate reduction decreased, but NRact still exceeded in-situ reduction. More extremely, under anoxia or after feeding 5-amino-4-imidazole carboxyamide ribonucleoside in the dark, NR was activated to the high light level; yet in spite of that, nitrate reduction in the leaf remained very low. It was examined whether the standard assay for NRact would overestimate the in-situ rates due to a dissociation of the inactive phospho-NR-14-3-3 complex after extraction and dilution, but no evidence for that was found. In-situ NR obviously operates below substrate saturation, except in the light at high ambient CO2. It is suggested that in the short term (2 h), nitrate reduction in situ is mainly limited by cytosolic NADH, and cytosolic nitrate becomes limiting only after the vacuolar nitrate pool has been partially emptied. PMID:10805452

  8. Genetic basis for nitrate resistance in Desulfovibrio strains.

    PubMed

    Korte, Hannah L; Fels, Samuel R; Christensen, Geoff A; Price, Morgan N; Kuehl, Jennifer V; Zane, Grant M; Deutschbauer, Adam M; Arkin, Adam P; Wall, Judy D

    2014-01-01

    Nitrate is an inhibitor of sulfate-reducing bacteria (SRB). In petroleum production sites, amendments of nitrate and nitrite are used to prevent SRB production of sulfide that causes souring of oil wells. A better understanding of nitrate stress responses in the model SRB, Desulfovibrio vulgaris Hildenborough and Desulfovibrio alaskensis G20, will strengthen predictions of environmental outcomes of nitrate application. Nitrate inhibition of SRB has historically been considered to result from the generation of small amounts of nitrite, to which SRB are quite sensitive. Here we explored the possibility that nitrate might inhibit SRB by a mechanism other than through nitrite inhibition. We found that nitrate-stressed D. vulgaris cultures grown in lactate-sulfate conditions eventually grew in the presence of high concentrations of nitrate, and their resistance continued through several subcultures. Nitrate consumption was not detected over the course of the experiment, suggesting adaptation to nitrate. With high-throughput genetic approaches employing TnLE-seq for D. vulgaris and a pooled mutant library of D. alaskensis, we determined the fitness of many transposon mutants of both organisms in nitrate stress conditions. We found that several mutants, including homologs present in both strains, had a greatly increased ability to grow in the presence of nitrate but not nitrite. The mutated genes conferring nitrate resistance included the gene encoding the putative Rex transcriptional regulator (DVU0916/Dde_2702), as well as a cluster of genes (DVU0251-DVU0245/Dde_0597-Dde_0605) that is poorly annotated. Follow-up studies with individual D. vulgaris transposon and deletion mutants confirmed high-throughput results. We conclude that, in D. vulgaris and D. alaskensis, nitrate resistance in wild-type cultures is likely conferred by spontaneous mutations. Furthermore, the mechanisms that confer nitrate resistance may be different from those that confer nitrite resistance. PMID:24795702

  9. Genetic basis for nitrate resistance in Desulfovibrio strains

    PubMed Central

    Korte, Hannah L.; Fels, Samuel R.; Christensen, Geoff A.; Price, Morgan N.; Kuehl, Jennifer V.; Zane, Grant M.; Deutschbauer, Adam M.; Arkin, Adam P.; Wall, Judy D.

    2014-01-01

    Nitrate is an inhibitor of sulfate-reducing bacteria (SRB). In petroleum production sites, amendments of nitrate and nitrite are used to prevent SRB production of sulfide that causes souring of oil wells. A better understanding of nitrate stress responses in the model SRB, Desulfovibrio vulgaris Hildenborough and Desulfovibrio alaskensis G20, will strengthen predictions of environmental outcomes of nitrate application. Nitrate inhibition of SRB has historically been considered to result from the generation of small amounts of nitrite, to which SRB are quite sensitive. Here we explored the possibility that nitrate might inhibit SRB by a mechanism other than through nitrite inhibition. We found that nitrate-stressed D. vulgaris cultures grown in lactate-sulfate conditions eventually grew in the presence of high concentrations of nitrate, and their resistance continued through several subcultures. Nitrate consumption was not detected over the course of the experiment, suggesting adaptation to nitrate. With high-throughput genetic approaches employing TnLE-seq for D. vulgaris and a pooled mutant library of D. alaskensis, we determined the fitness of many transposon mutants of both organisms in nitrate stress conditions. We found that several mutants, including homologs present in both strains, had a greatly increased ability to grow in the presence of nitrate but not nitrite. The mutated genes conferring nitrate resistance included the gene encoding the putative Rex transcriptional regulator (DVU0916/Dde_2702), as well as a cluster of genes (DVU0251-DVU0245/Dde_0597-Dde_0605) that is poorly annotated. Follow-up studies with individual D. vulgaris transposon and deletion mutants confirmed high-throughput results. We conclude that, in D. vulgaris and D. alaskensis, nitrate resistance in wild-type cultures is likely conferred by spontaneous mutations. Furthermore, the mechanisms that confer nitrate resistance may be different from those that confer nitrite resistance. PMID:24795702

  10. The Arabidopsis nitrate transporter NRT1.8 functions in nitrate removal from the xylem sap and mediates cadmium tolerance.

    PubMed

    Li, Jian-Yong; Fu, Yan-Lei; Pike, Sharon M; Bao, Juan; Tian, Wang; Zhang, Yu; Chen, Chun-Zhu; Zhang, Yi; Li, Hong-Mei; Huang, Jing; Li, Le-Gong; Schroeder, Julian I; Gassmann, Walter; Gong, Ji-Ming

    2010-05-01

    Long-distance transport of nitrate requires xylem loading and unloading, a successive process that determines nitrate distribution and subsequent assimilation efficiency. Here, we report the functional characterization of NRT1.8, a member of the nitrate transporter (NRT1) family in Arabidopsis thaliana. NRT1.8 is upregulated by nitrate. Histochemical analysis using promoter-beta-glucuronidase fusions, as well as in situ hybridization, showed that NRT1.8 is expressed predominantly in xylem parenchyma cells within the vasculature. Transient expression of the NRT1.8:enhanced green fluorescent protein fusion in onion epidermal cells and Arabidopsis protoplasts indicated that NRT1.8 is plasma membrane localized. Electrophysiological and nitrate uptake analyses using Xenopus laevis oocytes showed that NRT1.8 mediates low-affinity nitrate uptake. Functional disruption of NRT1.8 significantly increased the nitrate concentration in xylem sap. These data together suggest that NRT1.8 functions to remove nitrate from xylem vessels. Interestingly, NRT1.8 was the only nitrate assimilatory pathway gene that was strongly upregulated by cadmium (Cd(2+)) stress in roots, and the nrt1.8-1 mutant showed a nitrate-dependent Cd(2+)-sensitive phenotype. Further analyses showed that Cd(2+) stress increases the proportion of nitrate allocated to wild-type roots compared with the nrt1.8-1 mutant. These data suggest that NRT1.8-regulated nitrate distribution plays an important role in Cd(2+) tolerance. PMID:20501909

  11. Influence of phase formation on the interphase interactions during the aluminothermic reduction of zirconium from its dioxide

    NASA Astrophysics Data System (ADS)

    Krasikov, S. A.; Agafonov, S. N.; Chentsov, V. P.; Zhilina, E. M.

    2015-08-01

    The surface and volume properties of the zirconium-aluminum alloys synthesized by the aluminothermic reduction of zirconium from its dioxide are estimated theoretically and experimentally. The experimental values of surface tension and the metal and slag densities are used to calculate the interfacial characteristics that influence the separation of the products of metallothermic melting.

  12. Seasonal nitrate algorithms for nitrate retrieval using OCEANSAT-2 and MODIS-AQUA satellite data.

    PubMed

    Durairaj, Poornima; Sarangi, Ranjit Kumar; Ramalingam, Shanthi; Thirunavukarassu, Thangaradjou; Chauhan, Prakash

    2015-04-01

    In situ datasets of nitrate, sea surface temperature (SST), and chlorophyll a (chl a) collected during the monthly coastal samplings and organized cruises along the Tamilnadu and Andhra Pradesh coast between 2009 and 2013 were used to develop seasonal nitrate algorithms. The nitrate algorithms have been built up based on the three-dimensional regressions between SST, chl a, and nitrate in situ data using linear, Gaussian, Lorentzian, and paraboloid function fittings. Among these four functions, paraboloid was found to be better with the highest co-efficient of determination (postmonsoon: R2=0.711, n=357; summer: R2=0.635, n=302; premonsoon: R2=0.829, n=249; and monsoon: R2=0.692, n=272) for all seasons. Based on these fittings, seasonal nitrate images were generated using the concurrent satellite data of SST from Moderate Resolution Imaging Spectroradiometer (MODIS) and chlorophyll (chl) from Ocean Color Monitor (OCM-2) and MODIS. The best retrieval of modeled nitrate (R2=0.527, root mean square error (RMSE)=3.72, and mean normalized bias (MNB)=0.821) was observed for the postmonsoon season due to the better retrieval of both SST MODIS (28 February 2012, R2=0.651, RMSE=2.037, and MNB=0.068) and chl OCM-2 (R2=0.534, RMSE=0.317, and MNB=0.27). Present results confirm that the chl OCM-2 and SST MODIS retrieve nitrate well than the MODIS-derived chl and SST largely due to the better retrieval of chl by OCM-2 than MODIS. PMID:25762424

  13. Open-Source Photometric System for Enzymatic Nitrate Quantification

    PubMed Central

    Wittbrodt, B. T.; Squires, D. A.; Walbeck, J.; Campbell, E.; Campbell, W. H.; Pearce, J. M.

    2015-01-01

    Nitrate, the most oxidized form of nitrogen, is regulated to protect people and animals from harmful levels as there is a large over abundance due to anthropogenic factors. Widespread field testing for nitrate could begin to address the nitrate pollution problem, however, the Cadmium Reduction Method, the leading certified method to detect and quantify nitrate, demands the use of a toxic heavy metal. An alternative, the recently proposed Environmental Protection Agency Nitrate Reductase Nitrate-Nitrogen Analysis Method, eliminates this problem but requires an expensive proprietary spectrophotometer. The development of an inexpensive portable, handheld photometer will greatly expedite field nitrate analysis to combat pollution. To accomplish this goal, a methodology for the design, development, and technical validation of an improved open-source water testing platform capable of performing Nitrate Reductase Nitrate-Nitrogen Analysis Method. This approach is evaluated for its potential to i) eliminate the need for toxic chemicals in water testing for nitrate and nitrite, ii) reduce the cost of equipment to perform this method for measurement for water quality, and iii) make the method easier to carryout in the field. The device is able to perform as well as commercial proprietary systems for less than 15% of the cost for materials. This allows for greater access to the technology and the new, safer nitrate testing technique. PMID:26244342

  14. Low CO2 Prevents Nitrate Reduction in Leaves 1

    PubMed Central

    Kaiser, Werner M.; Förster, Jutta

    1989-01-01

    The correlation between CO2 assimilation and nitrate reduction in detached spinach (Spinacia oleracea L.) leaves was examined by measuring light-dependent changes in leaf nitrate levels in response to mild water stress and to artificially imposed CO2 deficiency. The level of extractable nitrate reductase (NR) activity was also measured. The results are: (a) In the light, detached turgid spinach leaves reduced nitrate stored in the vacuoles of mesophyll cells at rates between 3 and 10 micromoles per milligram of chlorophyll per hour. Nitrate fed through the petiole was reduced at similar rates as storage nitrate. Nitrate reduction was accompanied by malate accumulation. (b) Under mild water stress which caused stomatal closure, nitrate reduction was prevented. The inhibition of nitrate reduction observed in water stressed leaves was reversed by external CO2 concentrations (10-15%) high enough to overcome stomatal resistance. (c) Nitrate reduction was also inhibited when turgid leaves were kept in CO2-free air or at the CO2-compensation point or in nitrogen. (d) When leaves were illuminated in CO2-free air, activity of NR decreased rapidly. It increased again, when CO2 was added back to the system. The half-time for a 50% change in activity was about 30 min. It thus appears that there is a rapid inactivation/activation mechanism of NR in leaves which couples nitrate reductase to net photosynthesis. PMID:16667163

  15. Thermal decomposition hazard evaluation of hydroxylamine nitrate.

    PubMed

    Wei, Chunyang; Rogers, William J; Mannan, M Sam

    2006-03-17

    Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine family and it is a liquid propellant when combined with alkylammonium nitrate fuel in an aqueous solution. Low concentrations of HAN are used primarily in the nuclear industry as a reductant in nuclear material processing and for decontamination of equipment. Also, HAN has been involved in several incidents because of its instability and autocatalytic decomposition behavior. This paper presents calorimetric measurement for the thermal decomposition of 24 mass% HAN/water. Gas phase enthalpy of formation of HAN is calculated using both semi-empirical methods with MOPAC and high-level quantum chemical methods of Gaussian 03. CHETAH is used to estimate the energy release potential of HAN. A Reactive System Screening Tool (RSST) and an Automatic Pressure Tracking Adiabatic Calorimeter (APTAC) are used to characterize thermal decomposition of HAN and to provide guidance about safe conditions for handling and storing of HAN. PMID:16154263

  16. Photolysis of alkaline-earth nitrates

    NASA Astrophysics Data System (ADS)

    Kriger, L. D.; Miklin, M. B.; Dyagileva, E. P.; Anan'ev, V. A.

    2013-02-01

    Peroxynitrite and nitrite ions are the diamagnetic products of photolysis (with light at a wavelength of 253.7 nm) of alkaline-earth nitrates; the paramagnetic products and hydrogen peroxide were not found. The structural water in alkaline-earth nitrate crystals did not affect the qualitative composition of the photodecomposition products. The quantum yield of nitrite ions was 0.0012, 0.0038, 0.0078, and 0.0091 quanta-1 and that of peroxynitrite ions was 0.0070, 0.0107, 0.0286, and 0.0407 quanta-1 for Sr(NO3)2, Ba(NO3)2, Ca(NO3)2 · 4H2O, and Mg(NO3)2 · 6H2O, respectively.

  17. Gas phase chemistry of chlorine nitrate

    SciTech Connect

    Okumura, M.; Moore, T.A.; Crellin, K.C.

    1995-12-31

    Chlorine nitrate (ClONO{sub 2}) is a reservoir of both ClO{sub x} and NO{sub x} radicals in Earth`s stratosphere, and its decomposition is important in determining the abundance of stratospheric ozone. We present experimental and theoretical studies that explore the mechanisms and dynamics of processes leading to ClONO{sub 2} destruction in the stratosphere. Molecular beam photodissociation experiments have been performed to determine the decomposition pathways of ClONO{sub 2} upon excitation at 308 nm and to explore the possibility of a long-lived excited state. We have also investigated the reaction of chlorine nitrate with chloride ions Cl{sup -} in the gas phase. The gas phase ionic reaction may elucidate ionic mechanisms of heterogeneous reactions occurring on the surfaces of Polar Stratospheric Cloud particles and also raise doubts about proposed schemes to mitigate ozone depletion by electrifying the stratosphere.

  18. Synthesis, Spectroscopic, and Biological Studies on New Zirconium(IV) Porphyrins with Axial Ligand

    PubMed Central

    Bajju, Gauri D.; Devi, Gita; Katoch, Sapna; Bhagat, Madhulika; Deepmala; Ashu; Kundan, Sujata; Anand, Sunil Kumar

    2013-01-01

    A series of parasubstituted tetraphenylporphyrin zirconium(IV) salicylate complexes (SA/5-SSAZr(IV)RTPP, R = p-H, p-CH3, p-NO2, p-Cl, SA = salicylate, and 5-SSA = 5-sulfosalicylate) have been synthesized, and the spectral properties of free base porphyrins, their corresponding metallated, and axially ligated zirconium(IV) porphyrin compounds were compared with each other. A detailed analysis of ultraviolet-visible (UV-vis), proton nulcear magnetic resonance (1H NMR) spectroscopy, infrared (IR) spectroscopy, and elemental analysis suggested the transformation from free base porphyrins to zirconium(IV) porphyrins. The ability of the metal in this complex for extra coordination of solvent molecules was confirmed by ESI-MS spectra. Besides the fluorescence, cyclic voltammetry, and thermogravimetric studies, the complexes were also screened for antimicrobial and anticancer activities. Among all the complexes, 5-SSAZr(p-NO2TPP) shows high antibacterial activity. PMID:24106455

  19. Hydrogen Embrittlement in Zirconium: a Quasi-Continuum Density Functional Theory Study

    NASA Astrophysics Data System (ADS)

    Peng, Q.

    2012-02-01

    The hydrogen embrittlement in Zirconium becomes a very important and emergent issue for academia, industry and policy makers as a result of the Japan nuclear accident. The hydride formation, diffusion and embrittlement in zircolay will impact dramatically on the development of advanced nuclear energy systems, the life time extension of the current nuclear fleet and dry storage of spent nuclear fuel. Quasi-Continuum Density Functional Theory (QCDFT) is a powerful concurrent multiscale method based entirely on density functional theory (DFT) and allows quantum simulations of materials properties of a large system with billions of atoms. Using QCDFT modeling, we found that the presents of hydrogen at the cracktip of zirconium, both on crack surface and in-bulk, will form zirconium hydrides and embrittle the system. The concentration of hydrogen and orientation of crack plays important roles in such embrittlement. The mechanism of hydrogen embrittlement under various loading conditions will be discussed.

  20. Fabrication of anode support for solid oxide fuel cell using zirconium hydroxide as a pore former

    NASA Astrophysics Data System (ADS)

    Kim, Minchul; Lee, Jaehyung; Han, Joo-Hwan

    2011-03-01

    A novel method of fabricating NiO-YSZ (yttria stabilized zirconia) anode substrates is developed using a composite pore former, i.e., PMMA (polymethyl-methacrylate) and carbon black or zirconium hydroxide Zr(OH)4. By utilizing a composite pore former, both the shrinkage and porosity, which must be compatible with that of the electrolyte film and sufficient for the fuel supply and exhaust, are easily tailored. Carbon black and the inorganic pore former (Zr(OH)4) affect the shrinkage of the anode substrate more effectively than its porosity, while the polymer spheres (PMMA) adjust the porosity more effectively. In particular, the successful use of zirconium hydroxide as a fine pore former, instead of carbon black, suggests that other zirconium or nickel compound derivatives may be used as pore formers.

  1. Image analysis of modified cellulose fibers from sugarcane bagasse by zirconium oxychloride.

    PubMed

    Mulinari, D R; Cruz, T G; Cioffi, M O H; Voorwald, H J C; Da Silva, M L C P; Rocha, G J M

    2010-09-01

    Surface modification of natural fibers has been made using different methods. In this paper, cellulose fibers from sugarcane bagasse were bleached and modified by zirconium oxychloride in situ. The chemically modified cellulose fibers were compared to those of bleached ones. Cellulose fibers were modified with ZrO(2).nH(2)O nanoparticles through the use of zirconium oxychloride in acidic medium in the presence of cellulose fibers using urea as the precipitating agent. The spatial distribution characterization of hydrous zirconium oxide on cellulose fibers was carried out by combining both processing and image analyses obtained by SEM and statistical methodologies. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG) were also used to characterize the nanocomposite. Results indicated that ZrO(2).nH(2)O nanoparticles of about 30-80nm diameter deposited on cellulose fibers were heterogeneously dispersed. PMID:20599190

  2. Comparative behavior of titanium and zirconium in hydrofluoric-nitric acid pickling solutions

    SciTech Connect

    Sutter, E.M.M.; Hlawka, F.; Cornet, A. )

    1990-07-01

    The different behavior of titanium and zirconium in HF-HNO{sub 3} pickling solutions has been studied using electrochemical methods and Raman spectrometry. In each case, the depleting of the solutions during a pickling experiment could be correlated with the consumption of HF to form metal oxo or oxofluoro complexes. However, the mechanism of metal dissolution is quite different for the two metals. The titanium dissolution process in such solutions can be interpreted using a passivation model in which dissolution and passivation are two competing reactions at the surface of the bare metal. On the other hand, zirconium dissolution occurs through formation of an oxide film with ionic diffusion through the film being a rate-determining step. The particular role of strong acid added to the HF solution for pickling of titanium and zirconium is also discussed.

  3. Corrosion Behavior of Zirconium Treated Mild Steel with and Without Organic Coating: a Comparative Study

    NASA Astrophysics Data System (ADS)

    Ghanbari, Alireza; Attar, Mohammadreza Mohammadzade

    2014-10-01

    In this study, the anti-corrosion performance of phosphated and zirconium treated mild steel (ZTMS) with and without organic coating was evaluated using AC and DC electrochemical techniques. The topography and morphology of the zirconium treated samples were studied using atomic force microscopy (AFM) and field emission scanning electron microscope (FE-SEM) respectively. The results revealed that the anti-corrosion performance of the phosphate layer was superior to the zirconium conversion layer without an organic coating due to very low thickness and porous nature of the ZTMS. Additionally, the corrosion behavior of the organic coated substrates was substantially different. It was found that the corrosion protection performance of the phosphate steel and ZTMS with an organic coating is in the same order.

  4. Ion processing of zirconium ceramics by high-power pulsed beams

    NASA Astrophysics Data System (ADS)

    Ghyngazov, S. A.; Vasil'ev, I. P.; Surzhikov, A. P.; Frangulyan, T. S.; Chernyavskii, A. V.

    2015-01-01

    Modification of the structural phase state of the surface layer of zirconium ceramics irradiated by high-power pulsed beams of carbon ions at a pulse energy density of 3 J/cm2 is revealed using X-ray phase analysis and scanning electron microscopy. The analysis of roentgenograms indicates efficient formation of the high-temperature cubic modification of zirconium dioxide. The study of the depth distribution of oxygen ions using the secondary ion mass spectroscopy yields deficit of oxygen in the surface layer of the irradiated ceramics. A violation of the oxygen stoichiometry leads to a significant (by several orders of magnitude) increase in the conductivity of the samples under study. Mechanical characteristics (microhardness, nanohardness, and Young modulus) of the zirconium ceramics are determined after processing with high-power pulsed beams.

  5. Determination of fluoride in water - A modified zirconium-alizarin method

    USGS Publications Warehouse

    Lamar, W.L.

    1945-01-01

    A convenient, rapid colorimetric procedure using the zirconium-alizarin indicator acidified with sulfuric acid for the determination of fluoride in water is described. Since this acid indicator is stable indefinitely, it is more useful than other zirconium-alizarin reagents previously reported. The use of sulfuric acid alone in acidifying the zirconium-alizarin reagent makes possible the maximum suppression of the interference of sulfate. Control of the pH of the samples eliminates errors due to the alkalinity of the samples. The fluoride content of waters containing less than 500 parts per million of sulfate and less than 1000 p.p.m. of chloride may be determined within a limit of 0.1 p.p.m. when a 100-ml. sample is used.

  6. A novel zirconium K{alpha} imager for high energy density physics research

    SciTech Connect

    Akli, K. U.; Jiang, S.; Storm, M. S.; Krygier, A.; Freeman, R. R.; Sanchez del Rio, M.; Stephens, R. B.; Pereira, N. R.; Baronova, E. O.; Theobald, W.; Ping, Y.; McLean, H. S.; Patel, P. K.; Key, M. H.

    2011-12-15

    We report on the development and characterization of a zirconium K{alpha} imager for high energy density physics research. The imager consists of a spherically bent quartz crystal operating at 15.7 keV photon energy. We compare the performance of the imager in terms of integrated reflectivity (R{sub int}) and temperature dependent collection efficiency ({eta}{sub Te}) to that of the widely used Cu K{alpha} imager. Our collisional-radiative simulations show that the new imager can be reliably used up to 250 eV plasma temperature. Monte Carlo simulations show that for a 25 {mu}m thick tracer layer of zirconium, the contribution to K{alpha} production from photo-pumping is only 2%. We present, for the first time, 2D spatially resolved images of zirconium plasmas generated by a high intensity short pulse laser interacting with Zr solid targets.

  7. Porous desulfurization sorbent pellets containing a reactive metal oxide and an inert zirconium compound

    SciTech Connect

    Gardner, Todd H.; Gasper-Galvin, Lee D.

    1996-12-01

    Sorbent pellets for removing hydrogen sulfide from coal gas are prepared by combining a reactive oxide, in particular zinc oxide, with a zirconium compound such as an oxide, silicate, or aluminate of zirconium, and an inorganic binder and pelletizing and calcining the mixture. Alternately, the zinc oxide may be replaced by copper oxide or a combination of copper, molybdenum, and manganese oxides. The pellet components may be mixed in dry form, moistened to produce a paste, and converted to pellets by forming an aqueous slurry of the components and spray drying the slurry, or the reactive oxide may be formed on existing zirconium-containing catalyst-carrier pellets by infusing a solution of a salt of the active metal onto the existing pellets and firing at a high temperature to produce the oxide. Pellets made according to this invention show a high reactivity with hydrogen sulfide and durability such as to be useful over repeated cycles of sorption and regeneration.

  8. Features of hydrogen trapping and desorption during deposition of yttrium coating on zirconium in a gas discharge

    NASA Astrophysics Data System (ADS)

    Evsin, A. E.; Begrambekov, L. B.; Dovganyuk, S. S.

    2016-01-01

    Transport of hydrogen isotopes during the various regimes of deposition of yttrium coating on zirconium in argon plasma with addition of deuterium is studied. The influence of oxygen contamination in plasma-generating gas on the processes of trapping and desorption of hydrogen isotopes is also investigated. It is shown that deposition of yttrium coating on zirconium in Ar+5%D2 plasma enhances both hydrogen desorption from zirconium and deuterium trapping into zirconium in comparison to those under plasma exposure without deposition. Yttrium deposition in Ar+25%O2+5%D2 plasma, conversely, mitigates both hydrogen desorption and deuterium trapping. Hydrogen desorption from zirconium increases with the increase of energy of ions, bombarding the sample during deposition of the coating in oxygen-free plasma, but it, on the contrary, decreases in oxygen-containing plasma.

  9. The effects of deuteration on the nanostructured zirconium films deposited by pulsed laser deposition for nuclear fusion applications

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Wen, Chengwei; Liu, Qiong; Mao, Li; Zhou, Xiaosong; Long, Xinggui; Peng, Shuming

    2015-06-01

    In this paper, zirconium films have been deposited on Al2O3 (0 0 0 1) substrates by pulsed laser deposition (PLD) and then transferred to deuterium atmospheres. We find that the formation of Zr0.38D0.62 is under the deuterated temperatures of 923 K. The surface morphologies, electrical features and optical properties of as-grown zirconium films and zirconium deuteride films are systematically investigated as a function of three pulse repetition rates. It is found that the zirconium films show very smooth surfaces and high specular reflectivity. Moreover, exposure of the as-deposited zirconium films to deuterium atmospheres revealed that some pits formed on the surface of films. These defects induced by deuterium make the specular reflectivity and resistance of films change. The results of our investigation will be useful to optimize the environmental conditions for the First Mirror application in fusion devices.

  10. Understanding nitrate assimilation and its regulation in microalgae

    PubMed Central

    Sanz-Luque, Emanuel; Chamizo-Ampudia, Alejandro; Llamas, Angel; Galvan, Aurora; Fernandez, Emilio

    2015-01-01

    Nitrate assimilation is a key process for nitrogen (N) acquisition in green microalgae. Among Chlorophyte algae, Chlamydomonas reinhardtii has resulted to be a good model system to unravel important facts of this process, and has provided important insights for agriculturally relevant plants. In this work, the recent findings on nitrate transport, nitrate reduction and the regulation of nitrate assimilation are presented in this and several other algae. Latest data have shown nitric oxide (NO) as an important signal molecule in the transcriptional and posttranslational regulation of nitrate reductase and inorganic N transport. Participation of regulatory genes and proteins in positive and negative signaling of the pathway and the mechanisms involved in the regulation of nitrate assimilation, as well as those involved in Molybdenum cofactor synthesis required to nitrate assimilation, are critically reviewed. PMID:26579149

  11. Potential of dietary nitrate in angiogenesis.

    PubMed

    Rammos, Christos; Luedike, Peter; Hendgen-Cotta, Ulrike; Rassaf, Tienush

    2015-10-26

    Endothelial dysfunction with impaired bioavailability of nitric oxide (NO) is the hallmark in the development of cardiovascular disease. Endothelial dysfunction leads to atherosclerosis, characterized by chronic inflammation of the arterial wall and stepwise narrowing of the vessel lumen. Atherosclerosis causes deprivation of adequate tissue blood flow with compromised oxygen supply. To overcome this undersupply, remodeling of the vascular network is necessary to reconstitute and sustain tissue viability. This physiological response is often not sufficient and therapeutic angiogenesis remains an unmet medical need in critical limb ischemia or coronary artery disease. Feasible approaches to promote blood vessel formation are sparse. Administration of pro-angiogenic factors, gene therapy, or targeting of microRNAs has not yet entered the daily practice. Nitric oxide is an important mediator of angiogenesis that becomes limited under ischemic conditions and the maintenance of NO availability might constitute an attractive therapeutic target. Until recently it was unknown how the organism provides NO under ischemia. In recent years it could be demonstrated that NO can be formed independently of its enzymatic synthesis in the endothelium by reduction of inorganic nitrite under hypoxic conditions. Circulating nitrite derives from oxidation of NO or reduction of inorganic nitrate by commensal bacteria in the oral cavity. Intriguingly, nitrate is a common constituent of our everyday diet and particularly high concentrations are found in leafy green vegetables such as spinach, lettuce, or beetroot. Evidence suggests that dietary nitrate supplementation increases the regenerative capacity of ischemic tissue and that this effect may offer an attractive nutrition-based strategy to improve ischemia-induced revascularization. We here summarize and discuss the regenerative capacity of dietary nitrate on the vascular system. PMID:26516419

  12. GRAPHITE PRODUCTION UTILIZING URANYL NITRATE HEXAHYDRATE CATALYST

    DOEpatents

    Sheinberg, H.; Armstrong, J.R.; Schell, D.H.

    1964-03-10

    ABS>The graphitizing of a mixture composed of furfuryl alcohol binder and uranyl nitrate hexahydrate hardener and the subsequent curing, baking, and graphitizing with pressure being initially applied prior to curing are described. The pressure step may be carried out by extrusion, methyl cellulose being added to the mixture before the completion of extrusion. Uranium oxide may be added to the graphitizable mixture prior to the heating and pressure steps. The graphitizable mixture may consist of discrete layers of different compositions. (AEC)

  13. Potential of dietary nitrate in angiogenesis

    PubMed Central

    Rammos, Christos; Luedike, Peter; Hendgen-Cotta, Ulrike; Rassaf, Tienush

    2015-01-01

    Endothelial dysfunction with impaired bioavailability of nitric oxide (NO) is the hallmark in the development of cardiovascular disease. Endothelial dysfunction leads to atherosclerosis, characterized by chronic inflammation of the arterial wall and stepwise narrowing of the vessel lumen. Atherosclerosis causes deprivation of adequate tissue blood flow with compromised oxygen supply. To overcome this undersupply, remodeling of the vascular network is necessary to reconstitute and sustain tissue viability. This physiological response is often not sufficient and therapeutic angiogenesis remains an unmet medical need in critical limb ischemia or coronary artery disease. Feasible approaches to promote blood vessel formation are sparse. Administration of pro-angiogenic factors, gene therapy, or targeting of microRNAs has not yet entered the daily practice. Nitric oxide is an important mediator of angiogenesis that becomes limited under ischemic conditions and the maintenance of NO availability might constitute an attractive therapeutic target. Until recently it was unknown how the organism provides NO under ischemia. In recent years it could be demonstrated that NO can be formed independently of its enzymatic synthesis in the endothelium by reduction of inorganic nitrite under hypoxic conditions. Circulating nitrite derives from oxidation of NO or reduction of inorganic nitrate by commensal bacteria in the oral cavity. Intriguingly, nitrate is a common constituent of our everyday diet and particularly high concentrations are found in leafy green vegetables such as spinach, lettuce, or beetroot. Evidence suggests that dietary nitrate supplementation increases the regenerative capacity of ischemic tissue and that this effect may offer an attractive nutrition-based strategy to improve ischemia-induced revascularization. We here summarize and discuss the regenerative capacity of dietary nitrate on the vascular system. PMID:26516419

  14. Supplemental Cooling for Nitrate Salt Waste

    SciTech Connect

    Goldberg, Mitchell S.

    2015-08-19

    In July 2015, Los Alamos National Laboratory completed installation of a supplemental cooling system in the structure where remediated nitrate salt waste drums are stored. Although the waste currently is in a safe configuration and is monitored daily,controlling the temperature inside the structure adds another layer of protection for workers, the public,and the environment.This effort is among several layers of precautions designed to secure the waste.

  15. Bayesian model selection validates a biokinetic model for zirconium processing in humans

    PubMed Central

    2012-01-01

    Background In radiation protection, biokinetic models for zirconium processing are of crucial importance in dose estimation and further risk analysis for humans exposed to this radioactive substance. They provide limiting values of detrimental effects and build the basis for applications in internal dosimetry, the prediction for radioactive zirconium retention in various organs as well as retrospective dosimetry. Multi-compartmental models are the tool of choice for simulating the processing of zirconium. Although easily interpretable, determining the exact compartment structure and interaction mechanisms is generally daunting. In the context of observing the dynamics of multiple compartments, Bayesian methods provide efficient tools for model inference and selection. Results We are the first to apply a Markov chain Monte Carlo approach to compute Bayes factors for the evaluation of two competing models for zirconium processing in the human body after ingestion. Based on in vivo measurements of human plasma and urine levels we were able to show that a recently published model is superior to the standard model of the International Commission on Radiological Protection. The Bayes factors were estimated by means of the numerically stable thermodynamic integration in combination with a recently developed copula-based Metropolis-Hastings sampler. Conclusions In contrast to the standard model the novel model predicts lower accretion of zirconium in bones. This results in lower levels of noxious doses for exposed individuals. Moreover, the Bayesian approach allows for retrospective dose assessment, including credible intervals for the initially ingested zirconium, in a significantly more reliable fashion than previously possible. All methods presented here are readily applicable to many modeling tasks in systems biology. PMID:22863152

  16. Solid-phase zirconium and fluoride species in alkaline zircaloy cladding waste at Hanford.

    PubMed

    Reynolds, Jacob G; Huber, Heinz J; Cooke, Gary A; Pestovich, John A

    2014-08-15

    The United States Department of Energy Hanford Site, near Richland, Washington, USA, processed plutonium between 1944 and 1987. Fifty-six million gallons of waste of various origins remain, including waste from removing zircaloy fuel cladding using the so-called Zirflex process. The speciation of zirconium and fluoride in this waste is important because of the corrosivity and reactivity of fluoride as well as the (potentially) high density of Zr-phases. This study evaluates the solid-phase speciation of zirconium and fluoride using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Two waste samples were analyzed: one waste sample that is relatively pure zirconium cladding waste from tank 241-AW-105 and another that is a blend of zirconium cladding wastes and other high-level wastes from tank 241-C-104. Villiaumite (NaF) was found to be the dominant fluoride species in the cladding waste and natrophosphate (Na7F[PO4]2 · 19H2O) was the dominant species in the blended waste. Most zirconium was present as a sub-micron amorphous Na-Zr-O phase in the cladding waste and a Na-Al-Zr-O phase in the blended waste. Some zirconium was present in both tanks as either rounded or elongated crystalline needles of Na-bearing ZrO2 that are up to 200 μm in length. These results provide waste process planners the speciation data needed to develop disposal processes for this waste. PMID:24976128

  17. The initial, thermal oxidation of zirconium at room temperature

    NASA Astrophysics Data System (ADS)

    Lyapin, A.; Jeurgens, L. P. H.; Graat, P. C. J.; Mittemeijer, E. J.

    2004-12-01

    Angle-resolved x-ray photoelectron spectroscopy (ARXPS) and in situ spectroscopic ellipsometry have been used to investigate the initial oxidation of polycrystalline zirconium at room temperature in the partial oxygen pressure range of 1.3×10-7-1.3×10-4Pa. Detailed quantitative analysis of the measured Zr3d ARXPS spectra of the oxidized metal allowed separation of the intrinsic and extrinsic metallic and oxidic contributions to the spectra. It was shown that, in addition to the metallic contribution from the substrate and the oxidic contribution from stoichiometric ZrO2, two additional suboxidic components are contained in the measured Zr3d spectra of the oxidized Zr metal. As evidenced by angle-resolved XPS and in situ ellipsometry, both of these components can be attributed to a gradient of Zr enrichment in the region of the oxide film adjacent to the metal/oxide interface (with the highest Zr enrichment at the metal/oxide interface). Investigation of the oxide-film growth kinetics at various pO2, as determined independently using both techniques, showed the occurrence of an initial regime of very fast, electric-field-controlled growth, followed by a much slower oxidation stage. As a result, an, on average, nonstoichiometric oxide film develops. The observed effect of the pO2 on the low-temperature oxidation of Zr has been discussed in terms of the relationship between the fraction of coverage of the surface with physi- and chemisorbed oxygen and the applied pO2.

  18. Gaseous hydrogen embrittlement of a hydrided zirconium alloy

    NASA Astrophysics Data System (ADS)

    Huang, J. H.; Yeh, M. S.

    1998-03-01

    ZIRCALOY-4 plate specimens were gaseously hydrided up to 340 ppm H and then tested in a hydrogen gas environment of various pressures up to 2020 kPa at 25 °C, 100 °C, and 200 °C. Notched tensile specimens were chosen to better understand the “ductile-brittle transition” associated with hydrogen content and hydrogen pressure. The purpose of the present investigation is to understand the synergistic effect of hydrogen gas and internal hydrides on the mechanical properties of ZIRCALOY-4. The results showed that for both uncharged and hydrided specimens, the notch tensile strength decreased with increasing hydrogen pressure as well as increasing temperature. Compared with uncharged specimens, the specimens with hydrides had lower values of notch tensile strength. A ductile-brittle transition was found on specimens tested at 25 °C and at hydrogen pressures between 0 and 1010 kPa. For the specimen containing 220 ppm H, the reduction of area (RA) at 25 °C and at hydrogen pressures of 1010 kPa and above was drastically reduced, resulting in almost completely brittle behavior. This hydrogen and hydride-induced cracking was found to be an autocatalytic process. From the fractographic finding, the ductile-brittle transition was closely related to the precipitation and distribution of brittle hydrides. The ductile-brittle transition disappeared as the temperature increased to 100 °C and above. This can be attributed to the improved ductility of the zirconium matrix with increasing temperature.

  19. Ultrasonic texture characterization of aluminum, zirconium and titanium alloys

    SciTech Connect

    Anderson, A.J.

    1997-10-08

    This work attempts to show the feasibility of nondestructive characterization of non-ferrous alloys. Aluminum alloys have a small single crystal anisotropy which requires very precise ultrasonic velocity measurements for derivation of orientation distribution coefficients (ODCs); the precision in the ultrasonic velocity measurement required for aluminum alloys is much greater than is necessary for iron alloys or other alloys with a large single crystal anisotropy. To provide greater precision, some signal processing corrections need to be applied to account for the inherent, half-bandwidth offset in triggered pulses when using a zero-crossing technique for determining ultrasonic velocity. In addition, alloys with small single crystal anisotropy show a larger dependence on the single crystal elastic constants (SCECs) when predicting ODCs which require absolute velocity measurements. Attempts were made to independently determine these elastics constants in an effort to improve correlation between ultrasonically derived ODCs and diffraction derived ODCs. The greater precision required to accurately derive ODCs in aluminum alloys using ultrasonic nondestructive techniques is easily attainable. Ultrasonically derived ODCs show good correlation with derivations made by Bragg diffraction techniques, both neutron and X-ray. The best correlation was shown when relative velocity measurements could be used in the derivations of the ODCs. Calculation of ODCs in materials with hexagonal crystallites can also be done. Because of the crystallite symmetries, more information can be extracted using ultrasonic techniques, but at a cost of requiring more physical measurements. Some industries which use materials with hexagonal crystallites, e.g. zirconium alloys and titanium, have traditionally used texture parameters which provide some specialized measure of the texture. These texture parameters, called Kearns factors, can be directly related to ODCs.

  20. Thermal properties of zirconium diboride -- transition metal boride solid solutions

    NASA Astrophysics Data System (ADS)

    McClane, Devon Lee

    This research focuses on the thermal properties of zirconium diboride (ZrB2) based ceramics. The overall goal was to improve the understanding of how different transition metal (TM) additives influence thermal transport in ZrB2. To achieve this, ZrB2 with 0.5 wt% carbon, and 3 mol% of individual transition metal borides, was densified by hot-press sintering. The transition metals that were investigated were: Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, and Re. The room temperature thermal diffusivities of the compositions ranged from 0.331 cm2/s for nominally pure ZrB2 to 0.105 cm2/s for (Zr,Cr)B2 and converged around 0.155cm2/s at higher temperatures for all compositions. Thermal conductivities were calculated from the diffusivities, using temperature-dependent values for density and heat capacity. The electron contribution to thermal conductivity was calculated from measured electrical resistivity according to the Wiedemann-Franz law. The phonon contribution to thermal conductivity was calculated by subtracting the electron contribution from the total thermal conductivity. Rietveld refinement of x-ray diffraction data was used to determine the lattice parameters of the compositions. The decrease in thermal conductivity for individual additives correlated directly to the metallic radius of the additive. Additional strain appeared to exist for additives when the stable TM boride for that metal had different crystal symmetries than ZrB2. This research provided insight into how additives and impurities affect thermal transport in ZrB2. The research potentially offers a basis for future modeling of thermal conductivity in ultra-high temperature ceramics based on the correlation between metallic radius and the decrease in thermal conductivity.