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1

ELECTROLYTIC OXIDATION OF ZIRCONIUM IN NITRATE SOLUTIONS  

Microsoft Academic Search

Zirconiurn alloys used in the fabrication of nuclear fuel elements can ;\\u000a be disintegrated and converted to insoluble oxides by electrolytic treatment in ;\\u000a concentrated nitrate solutions. This reaction shows promise as a technique for ;\\u000a reprocessing nuclear fuels clad with Zircaloy-2. For a particular applied ;\\u000a voltage, nitric acid achieves the highest rate of attack, but the reaction can

Bomar

1961-01-01

2

Nitrates  

MedlinePLUS

... prescription instructions. Why do I need to take nitrates? Nitrates are used to treat the chest pain associated ... symptoms of congestive heart failure (CHF) . How do nitrates work? Nitrates are a vasodilator . Vasodilators widen (dilate) ...

3

Zirconium-containing coating composition  

SciTech Connect

This patent describes a binderless coating composition, free from alkaline and alkaline earth metallic oxides, hafnium, silica, and alumina, comprising substantially pure zirconium oxide suspended in an aqueous zirconyl nitrate and ammonium hydroxide gel.

Peterson, J.R.

1992-05-19

4

Zirconium isotope separation  

SciTech Connect

A method of separating zirconium isotopes by converting the zirconium to its iodide salt prior to separation by usual isotope methods is disclosed. After separation the desired isotopes are converted from the salt to the metal by the van Arkel-de Boer iodide process.

Siddall, M.B.

1984-12-11

5

Nitrate and periplasmic nitrate reductases  

PubMed Central

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

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

2014-01-01

6

Zirconium in sulfuric acid applications  

SciTech Connect

Zirconium is one of the few metals that resists attack by sulfuric acid at concentrations up to 75% and temperatures to boiling and above. This capability makes zirconium a good structural metal for use in 40 to 65% H/sub 2/SO/sub 4/ up to boiling temperatures and for weak acid concentrations at elevated temperatures. Zirconium's corrosion properties in sulfuric acid solutions are compared with nickel base alloys. Examples of applications and limitations in the use of zirconium are presented.

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

1986-02-01

7

Dopaminium nitrate  

PubMed Central

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

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

2014-01-01

8

Creep and creep fracture of zirconium and zirconium alloys  

NASA Astrophysics Data System (ADS)

The creep and creep failure mechanisms for zirconium and zirconium alloys have not been established, yet these properties are required to establish safe conditions for the interim dry storage of spent nuclear fuel. The purpose of this research, then, is to determine the relevant creep and creep fracture mechanisms controlling the deformation and failure of zirconium and zirconium alloys at elevated temperatures. Currently, the maximum allowable temperatures for the storage of spent nuclear fuel are defined by the Nuclear Regulatory Commission based on a limited set of experimental data. Recent changes in regulations will be evaluated and recommendations made regarding their applicability. Various studies in the past have reported that zirconium and zirconium alloys exhibit anomalous creep properties. A detailed analysis of the creep properties of zirconium and zirconium alloys is presented based on an extensive literature review. Next, developments in creep fracture phenomena in engineering materials over the past several decades will be discussed and related to the creep fracture of zirconium alloys. As will be discussed, the mechanism for plasticity can be intimately tied to the fracture mechanism. The results of uniaxial creep tests on zirconium at temperatures of 350--700°C and stresses of 8--70 MPa and uniaxial creep tests on Zircaloy-2 at temperatures of 300--600°C and stresses of 24--382 MPa and subsequent microstructural investigation using a scanning electron microscope will be discussed, particularly as relevant to the fracture mechanisms for this alloy.

Hayes, Troy Allyn

9

Electroless deposition process for zirconium and zirconium alloys  

DOEpatents

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.

Donaghy, Robert E. (Wilmington, NC); Sherman, Anna H. (Wilmington, NC)

1981-01-01

10

Electroless deposition process for zirconium and zirconium alloys  

DOEpatents

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.

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

1981-08-18

11

ZIRCONIUM AND HAFNIUM--1999 86.1 ZIRCONIUM AND HAFNIUM  

E-print Network

cladding, chemical piping in corrosive environments, heat exchangers, and various specialty alloys.I. du Pont de Nemours and Co. (DuPont). DuPont produced zircon from its Highland and Maxville heavy, and Western Zirconium, a subsidiary of Westinghouse Electric Company, Ogden, UT. Primary zirconium chemicals

12

Process for purifying zirconium sponge  

SciTech Connect

This patent describes a Kroll reduction process wherein a zirconium sponge contaminated with unreacted magnesium and by-product magnesium chloride is produced as a regulus, a process for purifying the zirconium sponge. It comprises: distilling magnesium and magnesium chloride from: a regulus containing a zirconium sponge and magnesium and magnesium chloride at a temperature above about 800{degrees} C and at an absolute pressure less than about 10 mmHg in a distillation vessel to purify the zirconium sponge; condensing the magnesium and the magnesium chloride distilled from the zirconium sponge in a condenser; and then backfilling the vessel containing the zirconium sponge and the condenser containing the magnesium and the magnesium chloride with a gas; recirculating the gas between the vessel and the condenser to cool the zirconium sponge from above about 800{degrees} C to below about 300{degrees} C; and cooling the recirculating gas in the condenser containing the condensed magnesium and the condensed magnesium chloride as the gas cools the zirconium sponge to below about 300{degrees} C.

Abodishish, H.A.M.; Kimball, L.S.

1992-03-31

13

ZIRCONIUM AND HAFNIUM By Joseph Gambogi  

E-print Network

1 ZIRCONIUM AND HAFNIUM By Joseph Gambogi Zirconium and hafnium are relatively abundant of commercial significance. Zirconium and containing alloys. hafnium are both contained in zircon at a ratio for zirconium and hafnium materials are developed by hafnium and is used in the chemical process industries

14

Aminoethyl nitrate – the novel super nitrate?  

PubMed Central

Long-term use of most organic nitrates is limited by development of tolerance, induction of oxidative stress and endothelial dysfunction. In this issue of the BJP, Schuhmacher et al. characterized a novel class of organic nitrates with amino moieties (aminoalkyl nitrates). Aminoethyl nitrate was identified as a novel organic mononitrate with high potency but devoid of induction of mitochondrial oxidative stress. Cross-tolerance to nitroglycerin or the endothelium-dependent agonist acetylcholine after in vivo treatment was not observed. Like all nitrates, aminoethyl nitrate induced vasorelaxation by activation of soluble guanylate cyclase. Thus, in contrast to the prevailing view, high potency in an organic nitrate is not necessarily accompanied by induction of oxidative stress or endothelial dysfunction. This work from Daiber's group is an important step forward in the understanding of nitrate bioactivation, tolerance phenomena and towards the development of better organic nitrates for clinical use. PMID:19732062

Bauersachs, Johann

2009-01-01

15

Organic derivatives of zirconium phosphate  

E-print Network

ORGANIC DERIVATIVES OF ZIRCONIUM PHOSPHATE A Thesis by STEVEN BERYL FINE Submitted to the Graduate College of Texas AAM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1980 Major Subject...: Chemistry ORGANIC DERIVATIVES OF ZIRCONIUM PHOSPHATE A Thesis by STEVEN BERYL FINE Approved as to style and content by: Dr. A raham Clearfield (c irman) Dr. Kurt Irgolic (member) 4~~@4 Dr. Martha Scott (member) Dr. C. S. Giam (department head...

Fine, Steven Beryl

2012-06-07

16

Nanolithography on Zirconium Surfaces  

NASA Astrophysics Data System (ADS)

We report, for the first time, scanning probe nanolithography on single crystal zirconium (Zr) surfaces using an atomic force microscope (AFM) tip in air. Preliminary experiments indicate that the size of the nanostructures written on Zr is 50 - 100 nm with applied DC voltages of 1 - 25 V and exposure times in the range of 1 - 60 seconds. We study the dependence of the size of the nanostructures on the magnitude of the applied voltage and current through the Zr substrate. This allows us to compare the results of SPM lithography on Zr with those on Si. Apparently, the nature of the current in these two cases is different. The current during high voltage Si oxidation exhibits Ohmic behavior and can reach 300 microamps. We believe that this current is the result of electrical breakdown in the meniscus of water resulting in conductivity dominated by electron mobility. In the case of Zr, the magnitude of the DC current is very small (less than 1 microamp) and exhibits typical Faradic behavior related with the transport of hydroxyl ions from an AFM tip down to the Zr surface. Lithographic oxidation of Zr surfaces is a very promising step toward the development of a comprehensive description of the nanolithographic process and complements our efforts to prepare Zr surfaces with novel properties via hyperthermal chemical reaction pathways.

Farkas, Natalia; Lyuksyutov, Sergei F.; Ramsier, Rex D.

2002-04-01

17

Transformation superplasticity of zirconium  

NASA Astrophysics Data System (ADS)

A tensile strain of 270 pct was achieved for coarse-grained zirconium subjected to transformation superplasticity conditions, where strain increments are accumulated upon repeated thermal cycling around the allotropic transformation temperature under the biasing effect of a uniaxial tensile stress. The strain increment per cycle was found to consist of two equal contributions from transformations on heating and cooling and to increase linearly with the applied stress. The measured strain increments are in good quantitative agreement with predictions based on the average internal stress during the transformation, which was determined independently from experimental transformation times. As the cycling frequency is raised, the average strain rate increases (a maximum value of 1.3·10-4 s-1 was measured), but the strain increment per cycle decreases above a critical cycling frequency, for which the sample gage section undergoes only a partial phase transformation. The resulting reduction in internal mismatch and increase in internal stress are modeled using the experimental observation that ?-Zr deforms by a mixture of diffusional and dislocation creep in the stress range of interest.

Zwigl, Peter; Dunand, David C.

1998-10-01

18

Mesostructured zirconium oxide  

SciTech Connect

The supramolecular templating technique was used to synthesize both hexagonal (Hx-ZrO{sub 2}) and lamellar (L-ZrO{sub 2}) phases of zirconium oxide. Under the conditions used in this work, the use of long chain primary amines and quaternary ammonium surfactants resulted in the exclusive formation of lamellar and hexagonal phases, respectively. The use of long chain cetyldimethylamine afforded a mixture of a hexagonal and a lamellar phase. Effects of synthesis parameters such as the ZrO{sub 2}/surfactant ratio, ZrO{sub 2}/water ratio, the nature of surfactant, the crystallization temperature and time on the formation of mesostructured ZrO{sub 2} were also studied. Addition of 1,3,5-trimethylbenzene (TMB) as a swelling agent led, in the presence of cetyltrimethylammonium bromide, to the formation of a lamellar phase rather than to pore enlargement. These materials were characterized by XRD, FTIR, XPS and EDX techniques. Regardless of their structure, the as-synthesized materials collapsed upon calcination. Treatment with monobasic potassium phosphate followed by calcination at 350 C led to the formation of a stable porous Zr-P oxide with a surface area as high as 540 m{sup 2}/g.

Liu, P.; Reddy, J.S.; Adnot, A.; Sayari, A. [Univ. Laval, Ste-Foy, Quebec (Canada)

1996-12-31

19

Ablation Resistant Zirconium and Hafnium Ceramics  

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

20

ZIRCONIUM AND HAFNIUM By Joseph M. Gambogi  

E-print Network

1 ZIRCONIUM AND HAFNIUM By Joseph M. Gambogi Zirconium and hafnium are relatively Australia and hafnium are both contained in 1995. zircon at a ratio of about 50 to 1. Zircon is a byproduct. Production Data for zirconium and hafnium materials are developed by the U.S. Bureau of Mines from one

21

Zirconium and hafnium in meteorites  

NASA Technical Reports Server (NTRS)

The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. The Zr/Hf abundance ratios for the chondrites vary in a rather narrow range, consistent with previously published observations from our group. Replicate analyses of new, carefully selected clean interior samples of the Cl chondrite Orgueil yield mean zirconium and hafnium abundances of 5.2 and 0.10 ppm, respectively. These abundances are lower than we reported earlier for two Cl chondrite samples which we now suspect may have suffered contamination. The new Cl zirconium and hafnium abundances are in closer agreement with predictions based on theories of nucleosynthesis than the earlier data.

Ehmann, W. D.; Chyi, L. L.

1974-01-01

22

ZIRCONIUM AND HAFNIUM--2001 86.1 ZIRCONIUM AND HAFNIUM  

E-print Network

, Inc. (a subsidiary of the Australian company Iluka Resources Ltd.). DuPont produced zircon from its and Magnesium Elektron Inc., Flemington, NJ. Secondary zirconium chemicals were produced by about 10 companies in nuclear fuel cladding, chemical processing equipment (pipes, valves, pumps), heat exchangers

23

Alkali metal nitrate purification  

DOEpatents

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.

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

1986-02-04

24

40 CFR 721.10602 - Lead niobium titanium zirconium oxide.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Lead niobium titanium zirconium oxide. 721.10602 Section...Substances § 721.10602 Lead niobium titanium zirconium oxide. (a) Chemical substance...chemical substance identified as lead niobium titanium zirconium oxide (PMN...

2014-07-01

25

40 CFR 721.10598 - Lead strontium titanium zirconium oxide.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Lead strontium titanium zirconium oxide. 721.10598 Section...Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance...substance identified as lead strontium titanium zirconium oxide (PMN...

2014-07-01

26

40 CFR 721.10601 - Lanthanum lead titanium zirconium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Lanthanum lead titanium zirconium oxide. 721.10601 Section...Substances § 721.10601 Lanthanum lead titanium zirconium oxide. (a) Chemical substance...substance identified as lanthanum lead titanium zirconium oxide (PMN...

2013-07-01

27

40 CFR 721.10598 - Lead strontium titanium zirconium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Lead strontium titanium zirconium oxide. 721.10598 Section...Substances § 721.10598 Lead strontium titanium zirconium oxide. (a) Chemical substance...substance identified as lead strontium titanium zirconium oxide (PMN...

2013-07-01

28

40 CFR 721.10601 - Lanthanum lead titanium zirconium oxide.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Lanthanum lead titanium zirconium oxide. 721.10601 Section...Substances § 721.10601 Lanthanum lead titanium zirconium oxide. (a) Chemical substance...substance identified as lanthanum lead titanium zirconium oxide (PMN...

2014-07-01

29

40 CFR 721.10602 - Lead niobium titanium zirconium oxide.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Lead niobium titanium zirconium oxide. 721.10602 Section...Substances § 721.10602 Lead niobium titanium zirconium oxide. (a) Chemical substance...chemical substance identified as lead niobium titanium zirconium oxide (PMN...

2013-07-01

30

Applications for zirconium and columbium alloys  

SciTech Connect

Currently, zirconium and columbium are used in a wide range of applications, overlapping only in the field of corrosion control. As a construction material, zirconium is primarily used by the nuclear power industry. The use of zirconium in the chemical processing industry (CPI) is, however, increasing steadily. Columbian alloys are primarily applied as superconducting alloys for research particle accelerators and fusion generators as well as in magnetic resonance imaging for medical diagnosis.

Condliff, A.F.

1986-09-01

31

2006 Minerals Yearbook ZIRCONIUM AND HAFNIUM  

E-print Network

subsidiary of Australian company Iluka Resources Ltd.). DuPont produced zircon from its heavy- mineral sands from intermediate zirconium chemicals, were produced by about 10 companies. Zirconia was produced from withheld to avoid disclosing company proprietary data. Domestic production of milled zircon and zirconium

32

Cylodextrin Polymer Nitrate  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

33

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use to begin operating in Georgia in 2004. Zirconium and hafnium metal were produced from zircon sand by two in a zirconium to hafnium ratio of about 50:1. Primary zirconium chemicals were produced by the Oregon metal

34

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use that will be trucked to a dry mill in Florida for separation. Zirconium and hafnium metals were produced from zircon are in the ore in a zirconium to hafnium ratio of about 50:1. Primary zirconium chemicals were produced

35

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

192 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida and at one mine in Virginia. Zirconium and hafnium metal. Typically, both metals are in the ore in a zirconium to hafnium ratio of about 50:1. Primary zirconium

36

Method of making crack-free zirconium hydride  

DOEpatents

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.

Sullivan, Richard W. (Denver, CO)

1980-01-01

37

Thermochemical nitrate destruction  

DOEpatents

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.

Cox, John L. (Richland, WA); Hallen, Richard T. (Richland, WA); Lilga, Michael A. (Richland, WA)

1992-01-01

38

Nitrate content and nitrate reductase activity in Rumex obtusifolius L  

Microsoft Academic Search

The aim of this work was to investigate the effect of nitrogen starvation and subsequent fentilization with nitrate or ammonium on nitrate content and nitrate reductase activity of Rumex obtusifolius L. under natural conditions.

A. Melzer; G. Gebauer; H. Rehder

1984-01-01

39

Penta­zirconium copper tribismuth  

PubMed Central

Penta­zirconium copper tribismuth, Zr5CuBi3, crystallizes in the hexa­gonal Hf5CuSn3 structure type. The asymmetric unit contains two Zr sites (site symmetries 3.2 and m2m), one Cu site (site symmetry 3.m) and one Bi site (site symmetry m2m). The environment of the Bi atoms is a tetra­gonal anti­prism with one added atom and a coordination number (CN) of 9. The polyhedron around the Zr1 atom is a defective cubo­octa­hedron with CN = 11. The bicapped hexa­gonal anti­prism (CN = 14) is typical for Zr2 atoms. The Cu atom is enclosed in a eight-vertex polyhedron (octa­hedron with two centered faces). The metallic type of bonding was indicated by an analysis of the inter­atomic distances and electronic structure calculation data. PMID:24109256

Balinska, Agnieszka; Tarasiuk, Ivan; Pavlyuk, Volodymyr

2013-01-01

40

Penta-zirconium copper tribismuth.  

PubMed

Penta-zirconium copper tribismuth, Zr5CuBi3, crystallizes in the hexa-gonal Hf5CuSn3 structure type. The asymmetric unit contains two Zr sites (site symmetries 3.2 and m2m), one Cu site (site symmetry 3.m) and one Bi site (site symmetry m2m). The environment of the Bi atoms is a tetra-gonal anti-prism with one added atom and a coordination number (CN) of 9. The polyhedron around the Zr1 atom is a defective cubo-octa-hedron with CN = 11. The bicapped hexa-gonal anti-prism (CN = 14) is typical for Zr2 atoms. The Cu atom is enclosed in a eight-vertex polyhedron (octa-hedron with two centered faces). The metallic type of bonding was indicated by an analysis of the inter-atomic distances and electronic structure calculation data. PMID:24109256

Balinska, Agnieszka; Tarasiuk, Ivan; Pavlyuk, Volodymyr

2013-01-01

41

Thermochemical nitrate destruction  

DOEpatents

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.

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

1992-06-02

42

SOIL NITRATE TESTS FOR WISCONSIN  

E-print Network

SOIL NITRATE TESTS FOR WISCONSIN CROPPING SYSTEMS L.G. Bundy Dept. of Soil Science University of Wisconsin #12;Why Use Soil Nitrate Tests? · Agronomic and environmental benefits · Predict corn N needs ­ Improved accuracy ­ Site-and year-specific · Minimize nitrate loss #12;#12;Preplant Soil Nitrate Test (PPNT

Balser, Teri C.

43

ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION  

SciTech Connect

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.

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

2008-01-01

44

Microstructural evolution in zirconium based alloys  

NASA Astrophysics Data System (ADS)

Zirconium alloys which exhibit practically all possible solid state phase transformations offer some unique opportunities for studying the fundamental aspects of phase transformations. The crystallographic features associated with the phase changes are much simpler in zirconium based systems, making them more suitable for providing a basic understanding of the relevant phenomena. Some of the important issues related to phase transformations research are identified and the manner, in which studies in zirconium alloys have contributed to the understanding of these issues, is discussed in this paper. Both the types of displacive transformations - shear-dominated and shuffle dominated - are encountered in zirconium alloys. The crystallography and the mechanism of such transformations are discussed, giving special reference to the morphological and sub-structural changes in zirconium martensites and to the fine particle and plate-shaped morphologies of the ?-phase. Morphological and crystallographical features of displacive and diffusional transformations have been compared. Several examples of mixed mode transformations, viz., the formation of ?-hydride phase, the active eutectoid decomposition and the formation of ordered ?-phases are cited and their respective mechanisms described.

Tewari, R.; Srivastava, D.; Dey, G. K.; Chakravarty, J. K.; Banerjee, S.

2008-12-01

45

2005 Minerals Yearbook ZirconiuM and HafniuM  

E-print Network

nemours & co. (duPont)] and iluka resources, inc. (a subsidiary of australian company iluka resources Ltd zirconium chemicals, produced from intermediate zirconium chemicals, were produced by about 10 companies disclosing company proprietary data. domestic production of milled zircon was unchanged and of zirconium

46

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

188 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use minerals. Typically, zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Two firms produced zircon from surface-mining operations in Florida and Virginia. Zirconium metal and hafnium metal

47

Atomic Layer Deposition of Insulating Hafnium and Zirconium Nitrides  

E-print Network

Atomic Layer Deposition of Insulating Hafnium and Zirconium Nitrides Jill S. Becker, Esther Kim, and conformal coatings of higher nitrides of hafnium and zirconium were produced by atomic layer deposition from-colored, and highly conducting. I. Introduction The mononitrides of hafnium and zirconium of stoi- chiometry MN (M

48

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

192 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use. Zirconium and hafnium elements were produced from zircon by two domestic producers, one in Oregon and the other in Utah. Typically, both elements are in the ore in a zirconium to hafnium ratio of about 50

49

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

188 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use. Zirconium and hafnium metal were produced from zircon by two domestic producers, one in Oregon and the other in Utah. Typically, both elements occur in the ore in a zirconium-to-hafnium ratio of about 50:1. Primary

50

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

186 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use and hafnium metal were produced from zircon by two domestic producers, one in Oregon and the other in Utah. Typically, both elements are in the ore in a zirconium-to-hafnium ratio of about 50:1. Zirconium chemicals

51

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use minerals. Typically, zirconium and hafnium are contained in zircon at a ratio of about 50 to 1. Two firms produced zircon from surface-mining operations in Florida and Virginia. Zirconium metal and hafnium metal

52

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

192 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use and hafnium metal were produced from zircon by two domestic producers, one in Oregon and the other in Utah. Typically, both elements are in the ore in a zirconium-to-hafnium ratio of about 50:1. Zirconium chemicals

53

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

188 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use and hafnium metal were produced from zircon by two domestic producers, one in Oregon and the other in Utah. Typically, both elements are in the ore in a zirconium-to-hafnium ratio of about 50:1. Zirconium chemicals

54

ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons unless otherwise noted) Domestic Production and Use minerals. Typically, both elements are in the ore in a zirconium-to-hafnium ratio of about 50:1. Two firms produced zircon from surface-mining operations in Florida and Virginia. Zirconium metal and hafnium metal

55

The chemical vapor deposition of zirconium carbide onto ceramic substrates  

SciTech Connect

Zirconium carbide is an attractive ceramic material due to its unique properties such as high melting point, good thermal conductivity, and chemical resistance. The controlled preparation of zirconium carbide films of superstoichiometric, stoichiometric, and substoichiometric compositions has been achieved utilizing zirconium tetrachloride and methane precursor gases in an atmospheric pressure high temperature chemical vapor deposition system.

Glass, John A, Jr.; Palmisiano, Nick, Jr.; Welsh, R. Edward

1999-07-01

56

Processing fissile material mixtures containing zirconium and/or carbon  

DOEpatents

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.

Johnson, Michael Ernest; Maloney, Martin David

2013-07-02

57

ZIRCONIUM AND HAFNIUM (Data in metric tons of zirconium oxide (ZrO ) equivalent, unless otherwise noted)2  

E-print Network

194 ZIRCONIUM AND HAFNIUM (Data in metric tons of zirconium oxide (ZrO ) equivalent, unless in Virginia. Zirconium and hafnium metal were produced from zircon sand by two domestic producers, one each, and sandblasting. The largest market for hafnium metal is an addition in superalloys. Salient Statistics

58

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2014 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2014-10-01

59

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2011 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2011-10-01

60

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2013 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2013-10-01

61

46 CFR 148.205 - Ammonium nitrate and ammonium nitrate fertilizers.  

Code of Federal Regulations, 2012 CFR

...Ammonium nitrate and ammonium nitrate fertilizers. 148.205 Section 148.205 ...Ammonium nitrate and ammonium nitrate fertilizers. (a) This section applies to...of ammonium nitrate and the following fertilizers composed of uniform,...

2012-10-01

62

Structural and electrical properties of zirconium doped yttrium oxide nanostructures  

NASA Astrophysics Data System (ADS)

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.

Bahari, Ali; Ebrahimzadeh, Masoud; Gholipur, Reza

2014-04-01

63

Iatrogenic ocular silver nitrate burn.  

PubMed

Two cases of silver nitrate burn occurred after treatment of superior limbic keratoconjunctivitis with a solid silver nitrate applicator. After medical treatment and several months of observation, visual acuity eventually returned to acceptable levels with minimal corneal scarring. These cases emphasize the fact that silver nitrate should be used very cautiously around the eye and only in a fresh 0.5-1% solution. The use of solid silver nitrate should be prohibited around the eye. PMID:4092479

Laughrea, P A; Arentsen, J J; Laibson, P R

64

7, 55535593, 2007 Nitrate aerosols  

E-print Network

ACPD 7, 5553­5593, 2007 Nitrate aerosols today and in 2030 S. E. Bauer et al. Title Page Abstract Discussions Nitrate aerosols today and in 2030: importance relative to other aerosol species and tropospheric, 5553­5593, 2007 Nitrate aerosols today and in 2030 S. E. Bauer et al. Title Page Abstract Introduction

Paris-Sud XI, Université de

65

Electrochemical impedance spectroscopic study of passive zirconium  

NASA Astrophysics Data System (ADS)

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.

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

2008-09-01

66

Sodium Zirconium Cyclosilicate in Hyperkalemia.  

PubMed

Background Hyperkalemia (serum potassium level, >5.0 mmol per liter) is associated with increased mortality among patients with heart failure, chronic kidney disease, or diabetes. We investigated whether sodium zirconium cyclosilicate (ZS-9), a novel selective cation exchanger, could lower serum potassium levels in patients with hyperkalemia. Methods In this multicenter, two-stage, double-blind, phase 3 trial, we randomly assigned 753 patients with hyperkalemia to receive either ZS-9 (at a dose of 1.25 g, 2.5 g, 5 g, or 10 g) or placebo three times daily for 48 hours. Patients with normokalemia (serum potassium level, 3.5 to 4.9 mmol per liter) at 48 hours were randomly assigned to receive either ZS-9 or placebo once daily on days 3 to 14. The primary end point was the exponential rate of change in the mean serum potassium level at 48 hours. Results At 48 hours, the mean serum potassium level had decreased from 5.3 mmol per liter at baseline to 4.9 mmol per liter in the group of patients who received 2.5 g of ZS-9, 4.8 mmol per liter in the 5-g group, and 4.6 mmol per liter in the 10-g group, for mean reductions of 0.5, 0.5, and 0.7 mmol per liter, respectively (P<0.001 for all comparisons) and to 5.1 mmol per liter in the 1.25-g group and the placebo group (mean reduction, 0.3 mmol per liter). In patients who received 5 g of ZS-9 and those who received 10 g of ZS-9, serum potassium levels were maintained at 4.7 mmol per liter and 4.5 mmol per liter, respectively, during days 3 to 15, as compared with a level of more than 5.0 mmol per liter in the placebo group (P<0.01 for all comparisons). Rates of adverse events were similar in the ZS-9 group and the placebo group (12.9% and 10.8%, respectively, in the initial phase; 25.1% and 24.5%, respectively, in the maintenance phase). Diarrhea was the most common complication in the two study groups. Conclusions Patients with hyperkalemia who received ZS-9, as compared with those who received placebo, had a significant reduction in potassium levels at 48 hours, with normokalemia maintained during 12 days of maintenance therapy. (Funded by ZS Pharma; ClinicalTrials.gov number, NCT01737697 .). PMID:25415807

Packham, David K; Rasmussen, Henrik S; Lavin, Philip T; El-Shahawy, Mohamed A; Roger, Simon D; Block, Geoffrey; Qunibi, Wajeh; Pergola, Pablo; Singh, Bhupinder

2014-11-21

67

International strategic minerals inventory summary report; zirconium  

USGS Publications Warehouse

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.

Towner, R.R.

1992-01-01

68

Zirconium oxidation on the atomic scale.  

PubMed

Zirconium alloys are used in the nuclear industry as fuel rod cladding. They are chosen for this role because of their good mechanical properties and low thermal neutron absorption. Oxidation of these alloys by coolant is one of the chief limiting factors of the fuel burn-up efficiency. The aim of the present study is to understand these oxidation mechanisms. As a first step, a fundamental study of the oxidation of commercially pure zirconium has been conducted using the 3D atom probe (3DAP). The current generation of 3DAPs allows both voltage and laser pulsing, providing data sets of many millions of ions. According to the literature the only stable oxide of zirconium is ZrO(2). However, the 3DAP shows that an initial layer a few nanometres thick forms with a composition of ZrO(1-)(x) when subjected to light oxidation. This result confirms and extends the work of Wadman et al. [Colloque de Physique 50 (1989) C8 303; Journal de Physique, 11 (1988) C6 49] and Wadman and Andrén [in: C.M. Euchen, A.M. Garde (Eds.), Zirconium in the Nuclear Industry: Ninth Symposium, ASTM STP 1132, ASTM, USA, 1991, p. 461], who used 1DAP techniques, obtaining reduced data sets. Segregation of hydrogen to the metal-oxide interface and a distinct ZrH phase were observed in this study. A novel kinetics study of the room temperature oxidation of zirconium showed the ZrO layer to be non-protective over the time period investigated (up to 1h). PMID:19101084

Hudson, Daniel; Cerezo, Alfred; Smith, George D W

2009-04-01

69

Purification of alkali metal nitrates  

DOEpatents

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.

Fiorucci, Louis C. (Hamden, CT); Gregory, Kevin M. (Woodridge, IL)

1985-05-14

70

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability; description of the zirconium-hafnium forming subcategory. 471.90 Section...POWDERS POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This...

2013-07-01

71

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.  

Code of Federal Regulations, 2012 CFR

...Applicability; description of the zirconium-hafnium forming subcategory. 471.90 Section...POWDERS POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This...

2012-07-01

72

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.  

Code of Federal Regulations, 2014 CFR

...Applicability; description of the zirconium-hafnium forming subcategory. 471.90 Section...POWDERS POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This...

2014-07-01

73

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.  

Code of Federal Regulations, 2011 CFR

...Applicability; description of the zirconium-hafnium forming subcategory. 471.90 Section...POWDERS POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the zirconium-hafnium forming subcategory. This...

2011-07-01

74

Nitrate content and nitrate reductase activity in Rumex obtusifolius L  

Microsoft Academic Search

With Rumex obtusifolius L., the influence of some environmental conditions on nitrate uptake and reduction were investigated. Nitrate concentrations of plant material were determined by HPLC, the activity of nitrate reductase by an “in vivo” test. As optimal incubation medium, a buffer containing 0.04 M KNO3; 0.25 M KH2PO4; 1.5% propanol (v\\/v); pH 8.0 was found. Vacuum infiltration caused an

G. Gebauer; A. Melzer; H. Rehder

1984-01-01

75

The kinetics of solid nucleation in zirconium  

SciTech Connect

The framework of classical nucleation theory coupled with statistical analysis was used to evaluate nucleation data from zirconium undercooling experiments. Bulk samples of high purity zirconium were processed in a containerless, high vacuum environment using electrostatic levitation at Space Systems/Loral in order to obtain sets of nucleation temperature data. The relationships between undercooling and initial material purity have been investigated. The nucleation rate equation parameters, preexponential factor and work of cluster formation, were determined using a statistical analysis technique. The mean undercooling values ranged from 326 to 348 K for material purities between 99.8 and 99.995%, respectively. The range of values for the preexponential factors, 10{sup 32}--10{sup 43}, and the activation energies, 64--88kT, for the classical nucleation rate equation also scaled with the purity levels.

Morton, C.W. [Teledyne Advanced Materials, La Vergne, TN (United States)] [Teledyne Advanced Materials, La Vergne, TN (United States); Hofmeister, W.H.; Bayuzick, R.J. [Vanderbilt Univ., Nashville, TN (United States)] [Vanderbilt Univ., Nashville, TN (United States); Rulison, A.J.; Watkins, J.L. [Space Systems/Loral, Palo Alto, CA (United States)] [Space Systems/Loral, Palo Alto, CA (United States)

1998-11-02

76

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

Code of Federal Regulations, 2012 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2012-10-01

77

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

Code of Federal Regulations, 2010 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2010-10-01

78

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

Code of Federal Regulations, 2014 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2014-10-01

79

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

Code of Federal Regulations, 2013 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2013-10-01

80

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

Code of Federal Regulations, 2011 CFR

...nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 ...nitrates, and certain ammonium nitrate fertilizers. (a) Except as provided in...Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more than 70%...

2011-10-01

81

Fatigue behavior of alpha-zirconium phosphate/epoxy nanocomposites.  

E-print Network

??Fatigue crack growth in ?-Zirconium phosphate/epoxy nanocomposites was investigated. A new fatigue testing technique was implemented for miniature samples. Two different methods ?strength of materials… (more)

Varadharajan, Balaji R.

2006-01-01

82

Procedures for heat treating fabricated equipment of zirconium alloys  

SciTech Connect

Zirconium is a common corrosion resistant material of construction used in a variety of chemical and industrial applications. In some applications, heat treatment is required or desirable after equipment fabrication to optimize the corrosion resistance and/or mechanical properties. Heat treatment can be performed using standard processes used for other materials but special attention should be given to zirconium`s properties when heat treatment is considered. This paper covers those conditions where heat treatment of zirconium equipment is utilized and describes the various heat treatment types and procedures.

Sutherlin, R.C. [Teledyne Wah Chang, Albany, OR (United States)

1995-10-01

83

Spectrum of Trebly Ionized Zirconium (Zr IV)  

Microsoft Academic Search

The zirconium spectrum is recorded on the 3 m normal incidence spectrograph of the Physics Department, Lund University; analysis of Zr IV is revised and extended. Identification of thirty-four 4p6 nd-4p5 4d2 (n = 4, 5, 6) transitions led to establish twelve 4p5 4d2 levels. Fifteen transitions are added to the analysis of the one-electron spectrum, establishing 7p levels and

K. Rahimullah; Zainul Abedeen Khan; M. S. Z. Chaghtai

1980-01-01

84

Spectrum of Trebly Ionized Zirconium (Zr IV)  

Microsoft Academic Search

The zirconium spectrum is recorded on the 3 m normal incidence spectrograph of the Physics Department, Lund University; analysis of Zr IV is revised and extended. Identification of thirty-four 4p6nd-4p5 4d2 (n = 4, 5, 6) transitions led to establish twelve 4p5 4d2 levels. Fifteen transitions are added to the analysis of the one-electron spectrum, establishing 7p levels and revising

K Rahimullah; Zainul Abedeen Khan; M S Z Chaghtai

1980-01-01

85

Autohydration of Nanosized Cubic Zirconium Tungstate  

PubMed Central

Nanoparticulate zirconium tungstate prepared through hydrothermal methods was found to autohydrate under ambient conditions. This results in positive thermal expansion, limiting its usefulness for controlled thermal expansion composites. TEM and BET studies provided strong evidence that the cause of autohydration is a result of structural defects present in the nanoparticles, while kinetics are governed by surface area, suggesting that processing methods can be used to minimize or overcome this problem. PMID:20521830

2010-01-01

86

Fluorometric determination of zirconium in minerals  

USGS Publications Warehouse

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.

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

1951-01-01

87

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

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410...Materials § 176.410 Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. (a)...

2013-10-01

88

Synthesis of zirconium dioxide by ultrasound assisted precipitation: effect of calcination temperature.  

PubMed

Nanostructured zirconium dioxide was synthesized from zirconyl nitrate using both conventional and ultrasound assisted precipitation in alkaline medium. The synthesized samples were calcinated at temperatures ranging from 400°C to 900°C in steps of 100°C. The ZrO(2) specimens were characterized using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal characteristics of the samples were studied via Differential Scanning Calorimetry-Thermo-Gravimetry Analysis (DSC-TGA). The influence of the calcination temperature on the phase transformation process from monoclinic to tetragonal to cubic zirconia and its consequent effect on the crystallite size and % crystallinity of the synthesized ZrO(2) was studied and interpreted. It was observed that the ultrasound assisted technique helped to hasten to the phase transformation and also at some point resulted in phase stabilization of the synthesized zirconia. PMID:21458352

Prasad, Krishnamurthy; Pinjari, D V; Pandit, A B; Mhaske, S T

2011-09-01

89

Nitrate assimilation in Lotus japonicus  

Microsoft Academic Search

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 muta- genesis programme are presented. In this programme, chlorate-resistant and photorespiratory

Antonio J. Marquez; Marco Betti; Margarita Garcia-Calderon; Peter Pal' ove-Balang; Pedro Diaz; Jorge Monza

2005-01-01

90

Nitrate losses from disturbed ecosystems  

Microsoft Academic Search

A systematic examination of nitrogen cycling in disturbed forest ecosystems demonstrates that eight processes, operating at three stages in the nitrogen cycle, could delay or prevent solution losses of nitrate from disturbed forests. An experimental and comparative study of nitrate losses from trenched plots in 19 forest sites throughout the United States suggests that four of these processes (nitrogen uptake

P. M. Vitousek; J. R. Gosz; C. C. Grier; J. M. Melillo; W. A. Reiners; R. L. Todd

1979-01-01

91

Evaluation of nitrate destruction methods  

SciTech Connect

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.

Taylor, P.A. [Oak Ridge National Lab., TN (United States); Kurath, D.E.; Guenther, R. [Pacific Northwest Lab., Richland, WA (United States)

1993-03-30

92

76 FR 47238 - Ammonium Nitrate From Russia  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-856; Second Review] Ammonium Nitrate From Russia Determination On...the antidumping duty order on ammonium nitrate from Russia would be likely...4249 (August 2011), entitled Ammonium Nitrate from Russia:...

2011-08-04

93

76 FR 11273 - Ammonium Nitrate From Russia  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-856 (Second Review)] Ammonium Nitrate From Russia AGENCY: United...the suspended investigation on ammonium nitrate from Russia...the suspended investigation on ammonium nitrate from Russia would be...

2011-03-01

94

76 FR 70366 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013, 2014

...NPRM for the Ammonium Nitrate Security Program. The agenda for the public...Department's Ammonium Nitrate Security Program Web site, at http://www.dhs...programs/ammonium-nitrate-security-program.shtm. This...

2011-11-14

95

76 FR 62311 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013, 2014

...NPRM) for the Ammonium Nitrate Security Program. The agenda for the public...Department's Ammonium Nitrate Security Program Web site in mid-October at http...programs/ammonium-nitrate-security-program.shtm. Each...

2011-10-07

96

Nitrate reductase from Rhodopseudomonas sphaeroides.  

PubMed Central

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

Kerber, N L; Cardenas, J

1982-01-01

97

Magnetic properties of nickel alloys with zirconium, niobium, and tungsten  

Microsoft Academic Search

The saturation magnetization and Curie point of nickel-- zirconium ; alloys were found to decrease with zirconium content. The saturation ; magnetization and Curie point are given by the formulas ( sigma \\/sub alloy\\/\\/ ; sigma \\/sub Ni\\/) = exp (-g\\/g\\/sub k\\/), and ) theta \\/sup alloy\\/\\/ theta \\/sup Ni\\/) = 1 ; - g( partial delta \\/ partial delta

A. D. Evdokimova; E. M. Sokolovskaya

1973-01-01

98

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

188 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida and at one mine in Virginia. Zirconium and hafnium metal, chemicals, metal alloys, welding rod coatings, and sandblasting. The largest market for hafnium metal

99

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

192 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida and one mine in Virginia. Zirconium and hafnium metal, chemicals, metal alloys, welding rod coatings, and sandblasting. The largest market for hafnium metal

100

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida and at one mine in Virginia. Zirconium and hafnium metal, metal alloys, welding rod coatings, and sandblasting. The largest market for hafnium metal

101

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless noted)  

E-print Network

190 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida. Zirconium and hafnium metal were produced from zircon sand, welding rod coatings, and sandblasting. The largest market for hafnium metal is as an addition

102

ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted)  

E-print Network

192 ZIRCONIUM AND HAFNIUM (Data in metric tons, unless otherwise noted) Domestic Production and Use: Zircon sand was produced at two mines in Florida. Zirconium and hafnium metal were produced from zircon, chemicals, metal alloys, welding rod coatings, and sandblasting. The largest market for hafnium metal

103

Processes for producing improved wear resistant coatings on zirconium shapes  

SciTech Connect

This patent describes the process of producing a zirconium oxide water resistant coating on a zirconium alloy surface comprising treating the alloy in a molten salt bath heated to a temperature of between 550/sup 0/ and 800/sup 0/C containing small amounts of sodium carbonate.

Haygarth, J.C.

1987-06-09

104

Corrosion resistance of zirconium and zirconium-titanium alloy in hot nitric acid  

Microsoft Academic Search

Since zirconium (Zr) has superior corrosion resistance to concentrated nitric acid (HNO3) at elevated temperature, it has been successfully used as a material for chemical plants to produce HNO3 or spent nuclear fuel reprocessing plants. However, the occurrence of stress corrosion cracking (SCC) has recently been reported in hot nitric acid conditions. The necessary conditions for SCC in Zr, and

Hiroo Nagano; Haruhiko Kajimura; Kazuo Yamanaka

1995-01-01

105

Zirconium fluoride glass - Surface crystals formed by reaction with water  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

106

Irradiation growth in zirconium and its alloys  

NASA Astrophysics Data System (ADS)

The UKAEA Northern Research Laboratories (Risley) have recently completed an underlying research study on irradiation growth in zirconium and its alloys. During this study, irradiation growth measurements have been made on a range of well-characterized single-crystal and polycrystalline iodide zirconium, commercial alloys Zircaloy-2 and Zr-2.5 wt% Nb, and high-purity zirconium-tin alloys in different metallurgical conditions following irradiation in the DIDO reactor at AERE Harwell. Irradiations were performed in three rigs operating at irradiation temperatures between 353 and 673 K. An important feature of the experimental programme was the capability to perform repeat length measurements on individual growth specimens at intervals during their irradiation programme. This facility has allowed accurate monitoring of the growth phenomenon and changes in growth behaviour induced by the combined effects of irradiation temperature and accumulated fast neutron dose over large dose ranges. This paper reviews the main experimental results from this programme and discusses them in terms of current understanding of the growth process. Thus, it has been observed that, in annealed Zircaloy-2 at temperatures between 553 and 673 K, a transition from saturating growth to accelerating growth rates occurs with increasing dose. The dose above which this "growth breakaway" takes place is seen to be inversely dependent on irradiation temperature in mis temperature range. The well-documented difference in growth behaviour between annealed and cold-worked Zircaloy-2 observed at relatively low irradiation temperatures, in which cold-worked material grows at a high linear rate over large dose ranges, is not observed at 673 K. Comparison is made with reported results on similar material irradiated in other irradiation facilities. The growth data are interpreted in terms of recent theories regarding the development during fast neutron irradiation of a cold-worked microstructure consisting of < a>- and < c>-type dislocations. Irradiation growth behaviour of annealed polycrystalline iodide zirconium between 353 and 673 K contrasts strongly with that in annealed Zircaloy-2 with low irradiation growth rates being observed over a large dose and temperature range. The influence of key irradiation parameters on the growth process have been examined in a series of studies initiated as part of a collaborative programme with AECL Chalk River Nuclear Labs. Final results from the studies on annealed and deformed single-crystal zirconium are reported here. They show that growth saturates rapidly at low dose in annealed single-crystal material irradiated at 353 and 553 K but that a gradual increase in growth strain is observed on irradiation to high dose at 553 K. Single-crystal specimens heavily swaged prior to irradiation at 353 K and given different pre-irradiation heat-treatments exhibit high near-linear or accelerating growth rates. These growth data are interpreted in terms of the importance of grain boundaries and twin boundaries as sinks for point defects which allow point defect separation and hence growth to continue to high dose. Finally, the results of growth experiments performed on Zr-0.1% Sn and Zr-1.5% Sn alloys at 353 and 553 K are reviewed. These experiments confirm the important role played by alloying additions and impurities on the growth process in zirconium and Zircaloy-2.

Rogerson, A.

1988-10-01

107

The Chemistry of Aqueous Solutions of Zirconium Salts (does the Zirconyl Ion EXIST?)  

Microsoft Academic Search

CONTENTS I. Introduction 656 II. Historical review 656 III. Properties of aqueous solutions of zirconium salts 657 IV. Complex formation by zirconium in aqueous and acidic solutions of its salts 660 V. Preparative chemistry of zirconium compounds and its relation to the chemical state of zirconium in solutions 664 Bibtex entry for this abstract Preferred format for this abstract (see

A. S. Solovkin; Z. N. Tsvetkova

1962-01-01

108

THE CHEMISTRY OF AQUEOUS SOLUTIONS OF ZIRCONIUM SALTS (DOES THE ZIRCONYL ION EXIST?)  

Microsoft Academic Search

CONTENTS I. Introduction 656 II. Historical review 656 III. Properties of aqueous solutions of zirconium salts 657 IV. Complex formation by zirconium in aqueous and acidic solutions of its salts 660 V. Preparative chemistry of zirconium compounds and its relation to the chemical state of zirconium in solutions 664

A S Solovkin; Z N Tsvetkova

1962-01-01

109

Polymerization of propylene promoted by zirconium benzamidinates.  

PubMed

New bis(N,N-trimethylsilylarylamidinate) zirconium dichloride complexes with various carbon substituents were prepared, and their solid as well as solution state structures were studied. In the polymerization of propylene, after activation by MAO, these catalysts provided two fractions. Ether soluble polymers were obtained at a low activity as sticky polymers with lower molecular weights, except with the o-OMe substituted complex. The solid fractions were composed of a highly isotactic polymer and a moderately syndiotactic polymer. An interesting linear correlation was found between the rates of the 2,1 and 3,1 insertions for the ether soluble fractions. PMID:24077612

Aharonovich, Sinai; Kulkarni, Naveen V; Zhang, Jia-Sheng; Botoshansky, Mark; Kapon, Moshe; Eisen, Moris S

2013-12-28

110

Electron-momentum distribution in zirconium  

SciTech Connect

The electron-momentum distribution in hexagonal-close-packed zirconium has been studied for the first time with use of a Compton-scattering technique. Measurements have been made by scattering 59.54-keV ..gamma.. rays. Theoretical computations have been carried out with use of the renormalized-free-atom model for various 4d-5s configurations. Best agreement between theory and experiment is found if the electron configuration is chosen as 4d/sup 3/5s/sup 1/.

Sharma, B.K.; Ahuja, B.L.

1988-08-15

111

Laser Photodetachment Electron Spectroscopy of Zirconium Dimers  

NASA Astrophysics Data System (ADS)

The electron affinity of the zirconium dimer has been measured using laser photodetachment electron spectroscopy (LPES). A photon beam emitted from a 532.2 nm CW laser crossed a 10 KeV beam of Zr2^- ions at a 90^o collision angle. The kinetic energies of the photodetached electrons were measured with a 160^o spherical sector energy analyzer. The electron spectrometer was operated in the constant pass energy mode.Photoelectron spectra were used to determine the electron affinity of the Zr2. Moreover, studies of photoelectron angular distribution measurements were also performed. Analysis of the angular distribution data is in process, and preliminary results will be presented.

Duvvuri, Srividya

2005-03-01

112

Nitrate concentrations under irrigated agriculture  

USGS Publications Warehouse

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.

Zaporozec, A.

1983-01-01

113

Nitrate and Prussic Acid Poisoning  

E-print Network

Nitrate and prussic acid poisoning in cattle are noninfectious conditions that can kill livestock. This publication explains the causes and symptoms of these conditions as well as preventive measures and sampling and testing steps....

Stichler, Charles; Reagor, John C.

2001-09-05

114

Nitrate Removal in NITREXTM Permeable Reactive Barriers  

E-print Network

Nitrate Removal in NITREXTM Permeable Reactive Barriers: Investigating Denitrification Using a 15 (particularly of nitrate) to aquatic systems is a growing problem. The NITREXTM Permeable Reactive Barrier (PRB) is a system for removing nitrate in groundwater. We investigated the nitrate removal processes and hydrology

Vallino, Joseph J.

115

Studies of nitrate reductase in marine phytoplankton  

Microsoft Academic Search

Certain marine phytoplankton contain the enzyme nitrate rcductase when growing on nitrate, but only low levels of enzyme were found during growth with ammonium or when the nitrogen source was depleted. Netted samples of oceanic phytoplankton contained the enzyme when taken from waters with nitrate concentrations 2-10 PM. Ammonium was assimilated in preference to nitrate in phytoplankton cultures supplied with

R. W. EPPLEY; J. L. COATSWORTH; LUCIA SOLÓRZANO

1969-01-01

116

A Zirconium Cermet for Transuranic Isotope Storage and Burning  

SciTech Connect

Transuranic (TRU) isotopes comprise {approx} 1% of the spent nuclear fuel (SNF) inventory from commercial light water reactors and supply the majority of the late-term (>300 years) heat load produced by SNF. These isotopes also have significant potential fission energy content that could be recovered in a fast reactor or accelerator driven system. Estimates by Wigeland, et al. suggest that removal of 99.9% of TRU isotopes and 97% of cesium, strontium, and europium from SNF could increase the linear drift load (i.e. capacity) of the proposed geologic repository at Yucca Mountain, NV by an order of magnitude. In other words, the waste packing capacity in Yucca Mt. would be increased and the recovered TRU could be used in a fast reactor system for energy production. One of the goals of the Advanced Fuel Cycle Initiative (AFCI) of the U.S. Department of Energy is to develop advanced nuclear technologies to recycle spent nuclear fuel without separating pure plutonium. The UREX+ family of solvent extraction and ion exchange processes can be manipulated to isolate TRU isotopes from uranium and other short-lived isotopes while leaving the Pu intimately mixed with other minor actinides (this corresponds with the UREX+1a process). The product TRU nitrate solution can be converted into oxide microspheres via direct denitration or sol-gel processing, leaving the TRU product in a stable oxide form for further processing. In addition, nuclear-grade zirconium metal can be recovered by recycling Zircaloy from the spent fuel cladding after the fuel has been chopped and dissolved away. The Zircaloy cladding hulls may be processed via a hydride/de-hydride process to produce high purity zirconium powder.These powder products can be combined via powder metallurgy techniques to produce a stable, safe storage form for TRU waste with the possibility of converting a long term waste liability into an advanced energy resource. Previous work by McDeavitt et al. at Argonne National Laboratory analyzed the production of a (Th,U)O-2-Zr cermet fuel using a cold-drawing process. This was a multi-pass process wherein a series of reductions were performed on each individual rod with a high temperature anneal between successive reductions to relieve strain hardening. This process allowed excellent control over the finished product matrix density allowing the user to pre-select the desired density by manipulating the reduction scheme. The final cold-drawn cermet contained a large fraction of damaged oxide particles, though the cause of this damage was not investigated due to project time constraints. It is believed that the high stress profile developed during cold deformation was the primary cause of this damage. The Fuel Cycle and Materials Laboratory (FCML) at Texas A and M University is currently analyzing a hot extrusion process to fabricate the proposed cermet and provide comparison data with the previous work. Initial studies have been completed and a system redesign is near completion. This paper presents the initial findings of the initial work and describes the new system setup. (authors)

Totemeier, Aaron R.; McDeavitt, Sean M. [Fuel Cycle and Materials Laboratory, Texas A and M University, College Station, TX 77843 (United States)

2007-07-01

117

Factors to consider for using zirconium in sulfuric acid services  

SciTech Connect

Zirconium is a pivotal material often specified for process equipment that handles highly corrosive sulfuric acid solutions. Because of the complicated nature of sulfuric acid, several factors should be addressed to ensure the durability of zirconium equipment. These factors include acid concentration, temperature, pressure, impurity, stress, crevices, welding, and surfaces condition. Depending on the situation, certain potential hazards to zirconium equipment can be prevented by applying control measures such as heat treatment, proper design and operating, inhibitor, surface conditioning and/or shot peening.

Fitzgerald, B.J. [Exxon Chemical Co., Baytown, TX (United States); Webber, R.G. [Exxon Chemical Co., Baton Rouge, LA (United States); Frechem, B.S. [Rohm and Haas Co., Spring House, PA (United States); Briegel, K.F. [Rohm and Haas Texas Co., Deer Park, TX (United States); Yau, T.L. [Teledyne Wah Chang, Albany, OR (United States)

1995-10-01

118

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

119

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

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

120

Fatigue behavior of alpha-zirconium phosphate/epoxy nanocomposites  

E-print Network

Fatigue crack growth in ±-Zirconium phosphate/epoxy nanocomposites was investigated. A new fatigue testing technique was implemented for miniature samples. Two different methods ?strength of materials and Rayleigh-Ritz - were used in determining...

Varadharajan, Balaji R.

2006-04-12

121

Investigation of Electrochemical Recovery of Zirconium from Spent Nuclear Fuels  

SciTech Connect

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.

Michael Simpson; II-Soon Hwang

2014-06-01

122

Electrical resistivity and thermal expansion of liquid titanium and zirconium  

SciTech Connect

The electrical resistivity and thermal expansion have been measured to twofold expanded states for titanium and to 60% expanded states for zirconium using the isobaric expansion apparatus. Results are consistent with the literature where there is overlap.

Gathers, G.R.

1983-01-01

123

Electrochemical study of corrosion phenomena in zirconium alloys  

E-print Network

Shadow corrosion of zirconium alloy fuel cladding in BWR environments, the phenomenon in which accelerated corrosion is experienced when the cladding surface is in close proximity to other metals, has become a potentially ...

Treeman, Nicole M

2005-01-01

124

Delayed hydride cracking of zirconium alloys  

SciTech Connect

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.

Yau, T.L. [Teledyne Wah Chang, Albany, OR (United States); Webster, R.T. [Webster (R.T.), Scio, OR (United States)

1995-10-01

125

Zirconium Hydride Space Power Reactor design.  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

126

Zirconium deformation behavior: insights from EBSD measurements.  

SciTech Connect

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.

Bingert, J. F. (John F.); Mason, T. A. (Thomas A.); Kaschner, G. C. (George C.); Maudlin, P. J. (Paul J.); Gray, G. T. (George T.), III

2001-01-01

127

Critical role of nitrogen during high temperature scaling of zirconium  

NASA Technical Reports Server (NTRS)

The mechanisms of scale cracking, scale color changes, and scale growth, and their interrelations, were studied in zirconium specimens at elevated temperatures in air, oxygen and nitrogen. Nitrogen was found to be responsible for monoclinic-to-cubic ZrO2 conversion, for scale cracking and breakaway on zirconium nitride, and for the formation of ZrN on the metal interface underneath an outer oxide layer.

Evans, E. B.; Tsangarakis, N.; Probst, H. B.; Garibotti, N. J.

1973-01-01

128

Material property correlations for the niobium-1% zirconium alloy  

E-print Network

MATERIAL PROPERTY CORRELATIONS FOR THE NIOBIUM-1% ZIRCONIUM ALLOY A Thesis by DAVID JAMES SENOR Submitted to the Office of Graduate Studies of Texas A6&l University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1989 Major Subject: Nuclear Engineering MATERIAL PROPERTY CORRELATIONS FOR THE NIOBUIM-1% ZIRCONIUM ALLOY A Thesis by DAVID JAMES SENOR Approved as to style and content by; . L. Peddicord (Chair of Committee) Frederick R. Best...

Senor, David James

2012-06-07

129

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

Code of Federal Regulations, 2011 CFR

...products with alkanol zirconium(4+) salt and silica, acetates (generic). 721...products with alkanol zirconium(4+) salt and silica, acetates (generic). ...products with alkanol zirconium(4+) salt and silica, acetates (PMN...

2011-07-01

130

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

Code of Federal Regulations, 2014 CFR

...products with alkanol zirconium(4+) salt and silica, acetates (generic). 721...products with alkanol zirconium(4+) salt and silica, acetates (generic). ...products with alkanol zirconium(4+) salt and silica, acetates (PMN...

2014-07-01

131

Reduction of nitrate in Shewanella  

SciTech Connect

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.

Gao, Haichun [University of Oklahoma; Yang, Zamin Koo [ORNL; Barua, Sumitra [University of Oklahoma, Norman; Reed, SB [Pacific Northwest National Laboratory (PNNL); Nealson, Kenneth H. [University of Southern California; Fredrikson, JK [Pacific Northwest National Laboratory (PNNL); Tiedje, James [Michigan State University, East Lansing; Zhou, Jizhong [University of Oklahoma

2009-01-01

132

Quercetin as colorimetric reagent for determination of zirconium  

USGS Publications Warehouse

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.

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

1953-01-01

133

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

Code of Federal Regulations, 2012 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2012-07-01

134

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

Code of Federal Regulations, 2013 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2013-07-01

135

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

Code of Federal Regulations, 2010 CFR

...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...Oxirane, substituted silylmethyl-, hydrolysis products with alkanol zirconium(4...oxirane, substituted silylmethyl-, hydrolysis products with alkanol...

2010-07-01

136

Understanding the Irradiation Behavior of Zirconium Carbide  

SciTech Connect

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 (ZrC) 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.

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

2013-10-11

137

Organic nitrates in portal hypertension.  

PubMed

In conclusion, chronic administration of organic nitrates, allowing for a nitrate-free interval each day, to cirrhotic patients reduces portal pressure with a variable, dose-dependent effect on azygos blood flow. The mechanisms of portal pressure reduction may vary according to the different doses and severity of liver disease. No studies to date have used dose-titration to determine the optimal beneficial effects in an individual patient, but some have at least compared the effect of different doses. Perhaps an end-point of mean arterial blood pressure reduction to 70 mm Hg could be suggested for future studies. The prophylactic benefit of nitrates for variceal bleeding still remains to be tested by controlled clinical trials. However, several problems in this evaluation need to be addressed, including patient compliance, selection of responders, evaluation of treatment, dose, and the duration of treatment. In contrast to the diminished expectations of propranolol for the prevention of rebleeding, there is mounting evidence of a major role for nitrates. PMID:8273802

Jones, A L; Hayes, P C

1994-01-01

138

4-Methyl­anilinium nitrate  

PubMed Central

In the crystal structure of the title compound, C7H10N+·NO3 ?, N—H?O hydrogen bonds involving the ammonium group and the nitrate O atoms result in the formation of zigzag chains propagating in [100]. PMID:21580662

Xu, Rui-jun

2010-01-01

139

A Novel Chemical Nitrate Destruction Process  

SciTech Connect

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.

Dziewinski, J.; Marczak, S.

1999-03-01

140

Comparative Studies on Nitrate Reductase in Agrostemma githago Induced by Nitrate and Benzyladenine.  

PubMed

NADH-nitrate reductase activity in excised embryos of Agrostemma githago develops in response to nitrate as well as benzyladenine. Induction of nitrate reductase by benzyladenine was much more susceptible to inhibition by a mixture of amino acid analogues and by cordycepin than induction by nitrate. In contrast, only induction of nitrate-nitrate reductase was decreased by chloramphenicol.NADH-cytochrome c reductase and reduced flavin mono-nucleotide-nitrate reductase activities were found to be associated with NADH-nitrate reductase and were induced by both nitrate and benzyladenine. When a partially purified enzyme sample was centrifuged in a linear 5 to 20% sucrose density gradient, a minor and a major band of NADH-cytochrome c reductase activity were observed. NADH-nitrate reductase cosedimented with the major band.The characteristics of nitrate-nitrate reductase and benzyl-adenine-nitrate reductase were compared by four methods but no differences could be detected: (a) Both enzymes sedimented with the same velocity during sucrose density gradient centrifugation. (b) Their distribution among fractions obtained by differential precipitation with (NH(4))(2)SO(4) was identical. (c) The elution profile of nitrate-nitrate reductase and benzyl-adenine-nitrate reductase after chromatography on diethyl-aminoethyl Sephadex A-25 columns showed no significant difference. (d) On polyacrylamide gel, the electrophoretic migration of the two enzymes was also identical. PMID:16658982

Dilworth, M F; Kende, H

1974-12-01

141

Comparative Studies on Nitrate Reductase in Agrostemma githago Induced by Nitrate and Benzyladenine 12  

PubMed Central

NADH-nitrate reductase activity in excised embryos of Agrostemma githago develops in response to nitrate as well as benzyladenine. Induction of nitrate reductase by benzyladenine was much more susceptible to inhibition by a mixture of amino acid analogues and by cordycepin than induction by nitrate. In contrast, only induction of nitrate-nitrate reductase was decreased by chloramphenicol. NADH-cytochrome c reductase and reduced flavin mono-nucleotide-nitrate reductase activities were found to be associated with NADH-nitrate reductase and were induced by both nitrate and benzyladenine. When a partially purified enzyme sample was centrifuged in a linear 5 to 20% sucrose density gradient, a minor and a major band of NADH-cytochrome c reductase activity were observed. NADH-nitrate reductase cosedimented with the major band. The characteristics of nitrate-nitrate reductase and benzyl-adenine-nitrate reductase were compared by four methods but no differences could be detected: (a) Both enzymes sedimented with the same velocity during sucrose density gradient centrifugation. (b) Their distribution among fractions obtained by differential precipitation with (NH4)2SO4 was identical. (c) The elution profile of nitrate-nitrate reductase and benzyl-adenine-nitrate reductase after chromatography on diethyl-aminoethyl Sephadex A-25 columns showed no significant difference. (d) On polyacrylamide gel, the electrophoretic migration of the two enzymes was also identical. PMID:16658982

Dilworth, Machi Fukuyama; Kende, Hans

1974-01-01

142

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...

143

8, 48114829, 2008 SOA and nitrate  

E-print Network

ACPD 8, 4811­4829, 2008 SOA and nitrate volatility in Mexico City C. J. Hennigan et al. Title Page of newly formed nitrate and water soluble organic aerosol in Mexico City C. J. Hennigan1 , A. P. Sullivan2 Geosciences Union. 4811 #12;ACPD 8, 4811­4829, 2008 SOA and nitrate volatility in Mexico City C. J. Hennigan

Paris-Sud XI, Université de

144

21 CFR 172.170 - Sodium nitrate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and...CONSUMPTION Food Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified...

2012-04-01

145

21 CFR 172.170 - Sodium nitrate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and...CONSUMPTION Food Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified...

2013-04-01

146

Nitrate removal from drinking water -- Review  

Microsoft Academic Search

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,

Anoop Kapoor; T. Viraraghavan

1997-01-01

147

21 CFR 172.170 - Sodium nitrate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Sodium nitrate. 172.170 Section 172.170 Food and...CONSUMPTION Food Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified...

2011-04-01

148

3, 59195976, 2003 The nitrate aerosol  

E-print Network

ACPD 3, 5919­5976, 2003 The nitrate aerosol field over Europe M. Schaap et al. Title Page Abstract/5919/ © European Geosciences Union 2003 Atmospheric Chemistry and Physics Discussions The nitrate aerosol field.schaap@phys.uu.nl) 5919 #12;ACPD 3, 5919­5976, 2003 The nitrate aerosol field over Europe M. Schaap et al. Title Page

Paris-Sud XI, Université de

149

6, 1071310731, 2006 Nitrate photolysis on  

E-print Network

ACPD 6, 10713­10731, 2006 Nitrate photolysis on ice surfaces T. Bartels-Rausch and D. J. Donaldson Chemistry and Physics Discussions HONO and NO2 evolution from irradiated nitrate-doped ice and frozen nitrate solutions T. Bartels-Rausch1,* and D. J. Donaldson1 1 University of Toronto, Ontario M5S 3H6

Paris-Sud XI, Université de

150

Nitration of Naphthol: A Laboratory Experiment.  

ERIC Educational Resources Information Center

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…

Mowery, Dwight F.

1982-01-01

151

6, 14551480, 2006 Modelling of nitrate  

E-print Network

are formed as fine mode ammonium nitrate or react on existing sea salt particles. The model results show that ammonium nitrate particles play a non-negligible role in the total aerosol composition in certain optical depth of ammonium nitrate is relatively small due to limited availability of ammonia and reaction

Boyer, Edmond

152

Elimination of phosphate and zirconium in the high-activity fraction resulting from TRUEX partitioning of ICPP zirconium calcines  

SciTech Connect

Laboratory testing was undertaken with the aim of developing a TRUEX flowsheet that would efficiently remove actinides from solutions of dissolved zirconium calcine and minimize the glass volume produced from the ensuing high-activity fraction. A TRUEX flowsheet is recommended for testing in the 2-cm centrifugal contactor pilot-plant based on the results from this testing. These laboratory tests show that zirconium recovery in the high activity fraction is minimized by scrubbing with an optimized NHF concentration of 0.2 M. This NH4F concentration in the scrub allowed the HEDPA strip concentration to be reduced from 0.04 M to 0.004 M because HEDPA is not consumed by zirconium. Complete TRU stripping was also achieved in these laboratory tests with 0.004 M HEDPA. Data from the small-scale laboratory batch contact tests were used in the Generic TRUEX Model (GTM) to evaluate the proposed flowsheet under counter-current conditions. GTM results indicate the raffinate will meet the Class A non-TRU limit of < 10 nCi/g in six extraction stages (O/A = 1), and quantitative actinide recovery will be achieved with the 0.004 M HEDPA in six strip stages (O/A = 1). Only 6.6 % of the initial zirconium concentration is anticipated to be recovered with the actinides, indicating the four scrub stages (O/A = 3) efficiently removes zirconium from the TRUEX solvent. In addition to recommending an improved TRUEX flowsheet for testing in the 2-cm centrifugal contactor pilot-plant, this work has shown that small reductions in zirconium extraction drastically improves flowsheet performance. These small changes in zirconium extraction can be accomplished by modifying the calcine dissolution parameters. Therefore, further calcine dissolution testing followed by TRUEX testing with the resulting feed solutions is also recommended.

Brewer, K.N.; Tillotson, R.D.; Tullock, P.A. [and others

1997-07-01

153

Cathodoluminescence imaging of oxidised zirconium alloys  

NASA Astrophysics Data System (ADS)

Cathodoluminescence (CL) imaging techniques have been applied to the characterisation of the zirconium oxide films formed from binary Zr alloy matrices using a homemade CL imaging system attached to an Hitachi S-570 scanning electron microscope (SEM). Evidence from the CL images shows the involvement of the individual Zircaloy alloying elements in the luminescence process. ?-annealed and slow-cooled samples which have strongly segregated alloying elements at their grain boundaries showed strong CL signals from these areas. Use of this heat treatment was necessary to compensate for the low resolution of the equipment. Strong CL signals were observed also from cracks in the oxides on some alloys and are believed to be caused by the redistribution of iron to the region adjacent to the crack, but below the original surface. Increasing redistribution of Fe with increasing oxidation temperature is seen in the CL images. The cyclic behaviour observed in the weight gain measurements is also observed in the CL intensity measurements. Experimental data from this investigation support the theory that this phenomenon is caused by the successive formation of cracks parallel and normal to the plane of the metal matrix.

Yueh, H. Ken; Cox, Brian

2004-01-01

154

Simulating porous oxide films on zirconium alloys  

NASA Astrophysics Data System (ADS)

This paper reports an attempt to simulate thick porous thermal oxide films on zirconium alloy specimens by successively applying layers of sol-gel zirconia to an initial thin oxide film. The intent was to aid in the interpretation of impedance spectra obtained from porous oxide films. To the extent that double-peaked Bode plots of phase angle, similar to those obtained from thermal oxides, were obtained in the impedance spectra the attempt was successful. However, the impedance spectra obtained on the simulated films were insensitive to the number of sol-gel layers. The film always appeared to be a double layer film, which was interpreted as the thermal oxide (produced during sintering the sol-gel oxide) under the sol-gel oxide. The impedance spectra were also insensitive to the nature of the porosity, which took the form of multiple high aspect ratio cracks in the simulated oxide films rather than the small pores observed in thermal oxide films. Accurate comparisons of oxide thicknesses by interferometry and impedance measurements with mercury contacts were rendered difficult by evidence for internal reflections (at the sol-gel/thermal oxide interface) in the former and incomplete contact problems in the latter.

Cox, B.; Wong, Y.-M.

1995-03-01

155

Author's personal copy A reactive force-field for Zirconium and Hafnium Di-Boride  

E-print Network

Author's personal copy A reactive force-field for Zirconium and Hafnium Di-Boride Afif Gouissem reactions High temperature materials a b s t r a c t Zirconium and Hafnium Di-Boride are the two major. Introduction The aim of this study is to develop transferable reactive force fields for Zirconium and Hafnium

Sharma, Pradeep

156

Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors  

E-print Network

Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors Dennis M (ALD) of smooth and highly conformal films of hafnium and zirconium oxides was studied using six metal alkylamide precursors for hafnium and zirconium. Water was used as an oxygen source during these experiments

157

J. Am. Chem. SOC.1991, 113, 3829-3837 3829 Zirconium and Hafnium Polyhydrides. Preparation and  

E-print Network

J. Am. Chem. SOC.1991, 113, 3829-3837 3829 Zirconium and Hafnium Polyhydrides. Preparation Abstract: Treatment of the zirconium and hafnium tetrahydroborate complexes M(BH4)4with trimethylphosphine-ligand distances in the zirconium complex are slightly longer than those in the hafnium complex, as expected from

Girolami, Gregory S.

158

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

SciTech Connect

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.

Bortun, Anatoly; Bortun, Mila; Pardini, James [MELChemicals Inc, 500 Barbertown Point Breeze Road, Flemington, NJ 08822 (United States)] [MELChemicals Inc, 500 Barbertown Point Breeze Road, Flemington, NJ 08822 (United States); Khainakov, Sergei A. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo, 33006 Oviedo (Spain)] [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo, 33006 Oviedo (Spain); Garcia, Jose R., E-mail: jrgm@uniovi.es [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo, 33006 Oviedo (Spain)

2010-02-15

159

U.S. GEOLOGICAL SURVEY--MINERALS INFORMATION 1 ZIRCONIUM AND HAFNIUM  

E-print Network

.S. production and of zircon, zirconium oxide, or other zirconium chemicals. The consumption of zircon. Milled zircon production was nearly hafnium and is used in the chemical process industries because. (DuPont). Both producers mined heavy-mineral sand deposits in Florida. U.S. producers of zirconium

160

Corrosion kinetics under high pressure of steam of pure zirconium and zirconium alloys followed by in situ thermogravimetry  

NASA Astrophysics Data System (ADS)

A new experimental thermogravimetric device has been installed to study in situ the corrosion behaviour of zirconium alloys under high pressure of steam. Corrosion tests up to 5 MPa of steam pressure have been performed on two materials, pure zirconium and Zircaloy-4 (Zy4), at around 415 °C. The rate-limiting step assumption was experimentally verified on Zy4. Unlike pure zirconium, its oxidation rate is not dependent on steam pressure. The experimental result obtained on this material is consistent with an oxygen vacancy diffusion rate-limiting step. For pure zirconium, the kinetic law is nearly linear during the corrosion process, which leads to propose an interface reaction rate-limiting step. Moreover, according to the isotope exchange experiments, the oxygen diffusion in the oxide formed on pure zirconium under high pressure of steam is very fast compared to that in the oxide of Zy4, which supports the thermogravimetric results. Finally, the impact of the SPPs on the corrosion resistance is briefly discussed in the last part of this paper from photoelectrochemical results.

Dali, Yacoub; Tupin, Marc; Bossis, Philippe; Pijolat, Michèle; Wouters, Yves; Jomard, François

2012-07-01

161

Measurement of Nitrate Efflux from Roots and Its Relation to Nitrate Accumulation in Two Oilseed Rape Cultivars  

Microsoft Academic Search

Studies have reported significant differences in nitrate accumulation among genotypes within a crop species, but the reason for these differences is not clear. This study investigated nitrate (NO3) efflux from roots of two oilseed rape cultivars (Brassica napus L. cvs. ZY821 and D89) and the relationship between nitrate efflux and plant nitrate accumulation. Nitrate efflux was estimated by measuring nitrate

Caibian Huang; Zhaohui Wang; Shengxiu Li; Sukhdev Singh Malhi

2012-01-01

162

Deconstructing nitrate isotope dynamics in aquifers  

NASA Astrophysics Data System (ADS)

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.

Granger, J.

2012-12-01

163

Catalyzed reduction of nitrate in aqueous solutions  

SciTech Connect

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.

Haas, P.A.

1994-08-01

164

High performance ammonium nitrate propellant  

NASA Technical Reports Server (NTRS)

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.

Anderson, F. A. (inventor)

1979-01-01

165

In-situ stabilization of radioactive zirconium swarf  

DOEpatents

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.

Hess, C.C.

1999-08-31

166

Producing carbon nanotube dispersions using polynuclear zirconium benzoate  

NASA Astrophysics Data System (ADS)

Aqueous dispersions of polynuclear zirconium benzoate with molar ratios of Zr: C6H5COO = 3-6, stable at pH 3.25-3.87 and having "solubilities" of up to 20 mg/mL by ZrO2, are prepared; in such dispersions, benzoate decomposes to ZrO2 at 500°C. Adding thin multiwalled carbon nanotubes to these dispersions makes it possible to isolate stable dispersions that contain both zirconium and nanotubes, mixtures suitable for producing composite coatings. It is shown that the concentration of nanotubes in mixtures with ZrO2 can vary within 1.7-50.6 wt %.

Van Nguyen, Huu; Luu, Son Tung; Rakov, E. G.

2013-02-01

167

Variant selection and transformation texture in zirconium alloy Excel  

NASA Astrophysics Data System (ADS)

The crystallographic texture and variant selection during phase transformations in zirconium alloy Excel (Zr-3.5% Sn-0.8% Mo-0.8% Nb) was investigated. It was shown that upon water-quenching from ?Zr + ?Zr or fully ?Zr regions, variant selection occurs during ?Zr ? ??Zr martensitic transformation. Also during air-cooling from the ?Zr + ?Zr region, only a partial memory effect and some transformation texture with variant selection was observed which is contrary to previous reports on zirconium alloys heat treated in the ?Zr + ?Zr region.

Sattari, M.; Holt, R. A.; Daymond, M. R.

2014-10-01

168

In-situ stabilization of radioactive zirconium swarf  

DOEpatents

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.

Hess, Clay C. (Idaho Falls, ID)

1999-01-01

169

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

SciTech Connect

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.

Cho, D. H.

1998-04-10

170

Zirconium determination by cooling curve analysis during the pyroprocessing of used nuclear fuel  

NASA Astrophysics Data System (ADS)

An alternative method to sampling and chemical analyses has been developed to monitor the concentration of zirconium in real-time during the casting of uranium products from the pyroprocessing of used nuclear fuel. The method utilizes the solidification characteristics of the uranium products to determine zirconium levels based on standard cooling curve analyses and established binary phase diagram data. Numerous uranium products have been analyzed for their zirconium content and compared against measured zirconium data. From this data, the following equation was derived for the zirconium content of uranium products:

Westphal, B. R.; Price, J. C.; Bateman, K. J.; Marsden, K. C.

2015-02-01

171

Stainless steel-zirconium alloy waste forms  

SciTech Connect

An electrometallurgical treatment process has been developed by Argonne National Laboratory to convert various types of spent nuclear fuels into stable storage forms and waste forms for repository disposal. The first application of this process will be to treat spent fuel alloys from the Experimental Breeder Reactor-II. Three distinct product streams emanate from the electrorefining process: (1) refined uranium; (2) fission products and actinides extracted from the electrolyte salt that are processed into a mineral waste form; and (3) metallic wastes left behind at the completion of the electrorefining step. The third product stream (i.e., the metal waste stream) is the subject of this paper. The metal waste stream contains components of the chopped spent fuel that are unaffected by the electrorefining process because of their electrochemically ``noble`` nature; this includes the cladding hulls, noble metal fission products (NMFP), and, in specific cases, zirconium from metal fuel alloys. The selected method for the consolidation and stabilization of the metal waste stream is melting and casting into a uniform, corrosion-resistant alloy. The waste form casting process will be carried out in a controlled-atmosphere furnace at high temperatures with a molten salt flux. Spent fuels with both stainless steel and Zircaloy cladding are being evaluated for treatment; thus, stainless steel-rich and Zircaloy-rich waste forms are being developed. Although the primary disposition option for the actinides is the mineral waste form, the concept of incorporating the TRU-bearing product into the metal waste form has enough potential to warrant investigation.

McDeavitt, S.M.; Abraham, D.P.; Keiser, D.D. Jr.; Park, J.Y.

1996-07-01

172

Nitrate deposition and impact on Adirondack streams  

SciTech Connect

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.

Simonin, H.A. [New York State Dept. of Environmental Conservation, Rome, NY (United States); Kretser, W.A. [New York State Dept. of Environmental Conservation, Ray Brook, NY (United States)

1997-12-31

173

Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms  

PubMed Central

Objective To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0–60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5–3.0 µm) and more uniformly shaped than AgZ. Conclusions Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection. PMID:23570016

Saengmee-anupharb, Sirikamon; Srikhirin, Toemsak; Thaweboon, Boonyanit; Thaweboon, Sroisiri; Amornsakchai, Taweechai; Dechkunakorn, Surachai; Suddhasthira, Theeralaksna; Kamaguchi, Arihide

2013-01-01

174

Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings  

Microsoft Academic Search

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

Kendall J Hollis; Maria I Pena

2010-01-01

175

Hydrogen pickup measurements in zirconium alloys: Relation to oxidation kinetics  

E-print Network

Hydrogen pickup measurements in zirconium alloys: Relation to oxidation kinetics Adrien Couet a to reduce hydrogen pickup during operation, and the associated cladding degradation. The present study focuses on precisely and accurately measuring hydrogen pickup fraction for a set of alloys to specifically

Motta, Arthur T.

176

Manufacturing process to reduce large grain growth in zirconium alloys  

DOEpatents

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.

Rosecrans, Peter M. (Niskayuna, NY)

1987-01-01

177

Mineral resource of the month: zirconium and hafnium  

USGS Publications Warehouse

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.

Gambogi, Joseph

2007-01-01

178

Discovery of Yttrium, Zirconium, Niobium, Technetium, and Ruthenium Isotopes  

E-print Network

Currently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Nystrom, A

2011-01-01

179

Discovery of Yttrium, Zirconium, Niobium, Technetium, and Ruthenium Isotopes  

E-print Network

Currently, thirty-four yttrium, thirty-five zirconium, thirty-four niobium, thirty-five technetium, and thirty-eight ruthenium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

A. Nystrom; M. Thoennessen

2011-02-11

180

CRYSTAL STRUCTURES OF TITANIUM, ZIRCONIUM, AND HAFNIUM AT HIGH PRESSURES  

Microsoft Academic Search

At high pressures, as determined by x-ray analysis, titanium and ; zirconium metal have a distorted, bodycentered-cubic structure. This phase ; persists on pressure release. The normal hexagonal close-packed structures are ; recovered when the metals are heated. An electronic shift must occur in the ; transition. Hafnium metal showed no such transition. (auth);

J. C. Jamieson

1963-01-01

181

Nanophase Nickel-Zirconium Alloys for Fuel Cells  

NASA Technical Reports Server (NTRS)

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.

Narayanan, Sekharipuram; Whitacre, jay; Valdez, Thomas

2008-01-01

182

The redistribution of impurities in zirconium at cyclic hydrogenation  

Microsoft Academic Search

The effect of dehydrogenation process temperature on the peculiarities of electronegative impurities redistribution in the volu me and on the surface of zirconium have been studied by kinetic method and Auger electron spectroscopy. The influence of hydrogenation and dehydrogenation processes on the density of electronic charge on 57Fe nucleus in Zr2Fe compound have been examined by method of nuclear ?-

D. V. Schur

183

Synthesis and Liquid Crystal Phase Transitions of Zirconium Phosphate Disks  

E-print Network

-shaped nanoparticles, and use it for the study of self-assembly and discotic liquid crystal phase transitions of discotic particles. The work was introduced by the control over the size and polydispersity of zirconium phosphate (ZrP) disks through synthesis...

Shuai, Min

2013-05-07

184

Physiological aspects of ammonium and nitrate fertilization  

Microsoft Academic Search

Various physiological effects of ammonium, nitrate and mixed ammonium?nitrate nutrition of plants have been studied in this laboratory during the last years. Some of the characteristic distinctions observed between plants growing on these nitrogen sources are described and discussed. Biomass production of ammonium?grown plants increased with K concentration in the nutrient medium between 0.1 to 3 mM , while nitrate?fed

S. H. Lips; E. O. Leidi; M. Silberbush; M. I. M. Soares; O. E. M. Lewis

1990-01-01

185

Trend Analyses of Nitrate in Danish Groundwater  

NASA Astrophysics Data System (ADS)

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?

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

2012-04-01

186

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

ERIC Educational Resources Information Center

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)

Bretherick, Leslie

1989-01-01

187

Rapid colorimetric determination of nitrate in plant tissue by nitration of salicylic acid  

Microsoft Academic Search

An analysis is described for the rapid determination of nitrate?N in plant extracts. The complex formed by nitration of salicylic acid under highly acidic conditions absorbs maximally at 410 nm in basic (pH>12) solutions. Absorbance of the chromophore is directly proportional to the amount of nitrate?N present. Ammonium, nitrite, and chloride ions do not interfere.

D. A. Cataldo; M. Maroon; L. E. Schrader; V. L. Youngs

1975-01-01

188

Removal of nitrate from groundwater by cyanobacteria: Quantitative assessment of factors influencing nitrate uptake  

SciTech Connect

The feasibility of biologically removing nitrate from groundwater was tested by using cyanobacterial cultures in batch mode under laboratory conditions. Results demonstrated that nitrate-contaminated groundwater, when supplemented with phosphate and some trace elements, can be used as growth medium supporting vigorous growth of several strains of cyanobacteria. As cyanobacteria grew, nitrate was removed from the water. Of three species tested, Synechococcus sp. strain PCC 7942 displayed the highest nitrate uptake rate, but all species showed rapid removal of nitrate from groundwater. The nitrate uptake rate increased proportionally with increasing light intensity up to 100 {micro}mol of photons m{sup {minus}2} s{sup {minus}1}, which parallels photosynthetic activity. The nitrate uptake rate was affected by inoculum size (i.e., cell density), fixed-nitrogen level in the cells in the inoculum, and aeration rate, with vigorously aerated, nitrate-sufficient cells in mid-logarithmic phase having the highest long-term nitrate uptake rate. Average nitrate uptake rates up to 0.05 mM NO{sub 3}{sup {minus}} h{sup {minus}1} could be achieved at a culture optical density at 730 nm of 0.5 to 1.0 over a 2-day culture period. This result compares favorably with those reported for nitrate removal by other cyanobacteria and algae, and therefore effective nitrate removal from groundwater using this organism could be anticipated on large-scale operations.

Hu, Q.; Westerhoff, P.; Vermaas, W.

2000-01-01

189

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

PubMed

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=22?M). 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

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

2014-04-01

190

Molecular Structure of Urea nitrate  

NSDL National Science Digital Library

Urea nitrate is a plastic explosive used for the charge on a nuclear weapon or as a component of a non-nuclear high explosive. It can also be used as a catalyst in Diels-Alder reactions of aromatic amines. It is favored by amateur terrorists because it is fairly easily derived from urea fertilizers or made by combining nitric and uric acids. Nitric acid can be found as waste from several industrial processes, while urea can be found as biological waste from most animals (in the form of urine). Thus, it provides similar explosive power, but lower cost, as TNT. Additionally, it is quite stable, with low friction and shock sensitivity, making it somewhat stable to work with, but also causing it to require an additional more unstable chemical detonator, called a booster, for use as a high explosive. However, in use as an industrial explosive, urea nitrate is used as a sensitizer to a less reactive fuel. It was the main component of the explosive used in the 1993 bombing of the World Trade Center.

2002-09-23

191

Occurrence of foliar nitrate reductase activity not induced by nitrate in symbiotic nitrogen-fed black alder (Alnus glutinosa)  

E-print Network

Occurrence of foliar nitrate reductase activity not induced by nitrate in symbiotic nitrogen-axenic conditions and supplied with nitrate or nitrate-free nutrient solution. The objectives were to: 1) evaluate the effect of nitrogen source and plant age on leaf nitrate reductase (NR) activity measured in vivo; 2

Paris-Sud XI, Université de

192

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

PubMed Central

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

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

2014-01-01

193

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

NASA Astrophysics Data System (ADS)

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 (15?) for nitrate uptake and nitrate efflux (2.0 ± 0.3‰ and 1.2 ± 0.4‰, respectively). The O isotope effects (18?) 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 15? for nitrate uptake can account for at most 40% of the organism-level N isotope effect (15?org) 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 (18?org:15?org) 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 18?org:15?org to rise appreciably above 1 when 15?org is low (e.g., yielding a ratio of 1.1 when 15?org 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.

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

2014-05-01

194

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...

195

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...

196

Nitric oxide, oxidants, and protein tyrosine nitration  

Microsoft Academic Search

The occurrence of protein tyrosine nitration under disease conditions is now firmly established and represents a shift from the signal transducing physiological actions of NO to oxidative and potentially pathogenic pathways. Tyrosine nitration is mediated by reactive nitrogen species such as peroxynitrite anion (ONOO-) and nitrogen dioxide (NO2), formed as secondary products of NO metabolism in the presence of oxidants

Rafael Radi

2004-01-01

197

Nitrates and Prussic Acid in Forages  

E-print Network

When nitrates and prussic acid accumulate in forage, the feed may not be safe for livestock consumption. Learn the symptoms of nitrate and prussic acid poisoning and which plants are most likely to pose a risk to livestock. Also learn sampling...

Provin, Tony; Pitt, John L.

2003-01-06

198

8, 1103911062, 2008 Nitrate in polar ice  

E-print Network

ACPD 8, 11039­11062, 2008 Nitrate in polar ice E. W. Wolff et al. Title Page Abstract Introduction in polar ice cores using evidence from snow and atmospheric measurements E. W. Wolff, A. E. Jones, S. J Geosciences Union. 11039 #12;ACPD 8, 11039­11062, 2008 Nitrate in polar ice E. W. Wolff et al. Title Page

Paris-Sud XI, Université de

199

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...

200

Winter Wheat Fertilization: Post Ammonium Nitrate  

Microsoft Academic Search

Summary The potential for overwinter losses of nitrogen by denitrification and leaching have led to the recommendation that nitrogen fertilization of winter wheat be done using ammonium nitrate broadcast in the spring. However, spring broadcast application of urea can result in significant loss of nitrogen by volatilization and immobilization by surface residues. Since prilled ammonium nitrate is not available for

R. Byron Irvine; Guy Lafond; Randy Kutcher

201

Sources of nitrate to ground water  

Microsoft Academic Search

There are a multitude of sources of nitrate to ground waters. Nitrogen undergoes a complex series of biochemical, chemical, and physical reactions in soils and waters, and thus the source of nitrate in ground waters is often difficult or impossible to ascertain with any degree of certainty. However, highly contaminated ground waters often have local sources that can be controlled.

Dennis Keeney; Robert A. Olson

1986-01-01

202

Transactions of the ASABE UNCERTAINTIES IN ASSESSING ANNUAL NITRATE  

E-print Network

Transactions of the ASABE UNCERTAINTIES IN ASSESSING ANNUAL NITRATE LOADS AND CONCENTRATION the uncertainty in annual nitrate loads and concentrations (such as annual average and median concentrations, France, were analyzed. Original (high frequency) nitrate concentration and flow data were numerically

Paris-Sud XI, Université de

203

40 CFR 721.7500 - Nitrate polyether polyol (generic name).  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Nitrate polyether polyol (generic name). ...Specific Chemical Substances § 721.7500 Nitrate polyether polyol (generic name). ...reporting. (1) The chemical substance nitrate polyether polyol (PMN...

2014-07-01

204

40 CFR 721.7500 - Nitrate polyether polyol (generic name).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Nitrate polyether polyol (generic name). ...Specific Chemical Substances § 721.7500 Nitrate polyether polyol (generic name). ...reporting. (1) The chemical substance nitrate polyether polyol (PMN...

2010-07-01

205

40 CFR 721.7500 - Nitrate polyether polyol (generic name).  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Nitrate polyether polyol (generic name). ...Specific Chemical Substances § 721.7500 Nitrate polyether polyol (generic name). ...reporting. (1) The chemical substance nitrate polyether polyol (PMN...

2012-07-01

206

40 CFR 721.7500 - Nitrate polyether polyol (generic name).  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Nitrate polyether polyol (generic name). ...Specific Chemical Substances § 721.7500 Nitrate polyether polyol (generic name). ...reporting. (1) The chemical substance nitrate polyether polyol (PMN...

2011-07-01

207

40 CFR 721.7500 - Nitrate polyether polyol (generic name).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Nitrate polyether polyol (generic name). ...Specific Chemical Substances § 721.7500 Nitrate polyether polyol (generic name). ...reporting. (1) The chemical substance nitrate polyether polyol (PMN...

2013-07-01

208

46 CFR 148.227 - Calcium nitrate fertilizers.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Calcium nitrate fertilizers. 148.227...Certain Materials § 148.227 Calcium nitrate fertilizers. This part does not apply to commercial grades of calcium nitrate fertilizers consisting...

2011-10-01

209

46 CFR 148.227 - Calcium nitrate fertilizers.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Calcium nitrate fertilizers. 148.227...Certain Materials § 148.227 Calcium nitrate fertilizers. This part does not apply to commercial grades of calcium nitrate fertilizers consisting...

2012-10-01

210

46 CFR 148.227 - Calcium nitrate fertilizers.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Calcium nitrate fertilizers. 148.227...Certain Materials § 148.227 Calcium nitrate fertilizers. This part does not apply to commercial grades of calcium nitrate fertilizers consisting...

2014-10-01

211

46 CFR 148.227 - Calcium nitrate fertilizers.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Calcium nitrate fertilizers. 148.227...Certain Materials § 148.227 Calcium nitrate fertilizers. This part does not apply to commercial grades of calcium nitrate fertilizers consisting...

2013-10-01

212

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

213

78 FR 32690 - Certain Ammonium Nitrate From Ukraine  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-894 (Review)] Certain Ammonium Nitrate From Ukraine Determination On...antidumping duty order on certain ammonium nitrate from Ukraine would be likely...May 2013), entitled Certain Ammonium Nitrate from Ukraine:...

2013-05-31

214

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

NASA Astrophysics Data System (ADS)

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.

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

2011-06-01

215

Dissimilatory nitrate reduction in Clostridium tertium.  

PubMed

Fermentation balance studies were carried out on Clostridium tertium grown with and without nitrate in the medium. Nitrate reduction increased the efficiency of energy produced from glucose by permitting the utilization of additional sites of substrate level phosphorylation. The effect was even more dramatic in C. tertium than in C. perfringens, with increased cell yields of about 30% being observed in the former compared with 20% in the latter. Unlike C. perfringens, C. tertium responded to the presence of nitrate in the medium with an increased growth rate. A slight increase in the Y ATP of these cultures was also observed, and quantitatively, this appeared to be consistent with the prediction of Stouthammer and Bettenhaussen that Y ATP will vary with the growth rate. Thus, C. tertium, like C. perfringens, was able to use nitrate as an electron acceptor in conjunction with its energy metabolism, suggesting that this may be widespread among the nitrate-reducing anaerobes. PMID:203129

Hasan, M; Hall, J B

1977-01-01

216

Complexation Chemistry of Zirconium(IV), Uranium(VI), and Iron(III) with Acetohydroxamic Acid  

Microsoft Academic Search

The complexation of zirconium(IV), uranium(VI), and iron(III) with acetohydroxamic acid (AHA) has been analyzed spectrophotometrically in various ionic strengths at 25°C. Arsenazo III (AAIII) was used as an indicator for unbound zirconium. The SQUAD computational program was employed to evaluate the stability constants. Conditional stability constants of four zirconium complexes Zr(AAIII), , Zr(AHA), and were determined in 1 mol · L HClO4 as

Brent S. Matteson; Peter Tkac; Alena Paulenova

2010-01-01

217

Alternative Processing of High Temperature Hafnium and Zirconium Based Materials  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

218

Computer simulation of displacement cascades in {alpha}-zirconium  

SciTech Connect

The damage produced in {alpha}-zirconium at 100 K by displacement cascades with energy up to 20 keV has been investigated by MD simulations. In agreement with modelling of fcc and bcc metals, the defect production efficiency in zirconium is well below the NRT estimate. The number and size of clusters, both vacancy and interstitial, are increased by increasing PKA energy, and clusters containing up to 25 interstitials and 30 vacancies were formed by 20 keV cascades. Most interstitial clusters have dislocation character with perfect Burgers vectors of the form 1/3<11{bar 2}0>, but a few metastable clusters are formed and are persistent over the timescale of MD simulations. Collapse of the 30-vacancy cluster to a faulted loop on the prism plane was found to occur over a period of more than 100 ps.

Gao, F.; Wooding, S.J.; Bacon, D.J.; Calder, A.F. [Univ. of Liverpool (United Kingdom). Dept. of Materials Science and Engineering; Howe, L.M. [AECL Chalk River Labs., Ontario (Canada)

1997-11-01

219

Modelling zirconium hydrides using the special quasirandom structure approach.  

PubMed

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

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

2013-05-28

220

Radioactivity in zirconium oxide powders used in industrial applications.  

PubMed

Recent work involving the decommissioning of a former ceramic manufacturing facility licensed by the Nuclear Regulatory Commission for activities involving depleted uranium oxide has uncovered the presence of unexpected high levels of natural radioactivity in non-licensed zirconium oxide powders also used in the same facility. A comparison between the levels of source material found in samples of this material and the current regulatory guidance for licensed activities and decommissioning has been conducted. It has been determined that the radioactivity in the zirconium oxide is of a high enough magnitude to raise health physics concerns in the areas of licensing and regulatory compliance, decontamination criteria, and worker health and safety. An examination of these areas has been conducted and the implications associated with our findings are presented. PMID:2032840

Lischinsky, J; Vigliani, M A; Allard, D J

1991-06-01

221

Effects of solutes on damage production and recovery in zirconium  

SciTech Connect

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.

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

1986-04-01

222

Corrosion behavior of stainless steel-zirconium alloy waste forms  

SciTech Connect

Stainless steel-zirconium (SS-Zr) alloys are being considered as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The baseline waste form for spent fuels from the EBR-11 reactor is a stainless steel-15 wt.% zirconium (SS-15Zr) alloy. This article briefly reviews the microstructure of various SS-Zr waste form alloys and presents results of immersion corrosion and electrochemical corrosion tests performed on these alloys. The electrochemical tests show that the corrosion behavior of SS-Zr alloys is comparable to those of other alloys being considered for the Yucca Mountain geologic repository. The immersion tests demonstrate that the SS-Zr alloys are resistant to selective leaching of fission product elements and, hence, suitable as candidates for high-level nuclear waste forms.

Abraham, D.P.; Simpson, L.J.; DeVries, M.J.; Callahan, D.E.

1999-07-01

223

Corrosion testing of stainless steel-zirconium metal waste forms  

SciTech Connect

Stainless steel-zirconium (SS-Zr) alloys have been developed as waste forms for the disposal of metallic waste generated during the electrometallurgical treatment of spent nuclear fuel. The waste forms incorporate irradiated cladding hulls, components of the alloy fuel, noble metal fission products, and actinide elements. The baseline waste form is a stainless steel-15 wt% zirconium (SS-15Zr) alloy. This article presents microstructures and some of the corrosion studies being conducted on the waste form alloys. Electrochemical corrosion, immersion corrosion, and vapor hydration tests have been performed on various alloy compositions to evaluate corrosion behavior and resistance to selective leaching of simulated fission products. The SS-Zr waste forms immobilize and retain fission products very effectively and show potential for acceptance as high-level nuclear waste forms.

Abraham, D.P.; Simpson, L.J.; Devries, M.J.; McDeavitt, S.M.

1999-07-01

224

40 CFR 471.90 - Applicability; description of the zirconium-hafnium forming subcategory.  

Code of Federal Regulations, 2010 CFR

...PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Zirconium-Hafnium Forming Subcategory § 471.90 Applicability; description of the...

2010-07-01

225

Synthesis and analytical application of tribromocarboxyarsenazo as a new chromogenic reagent for zirconium.  

PubMed

A new chromogenic reagent tribromocarboxyarsenazo has been synthesized and the chromogenic reaction of this reagent with zirconium studied. In the medium of 0.5 mol/1 HCl, a blue complex is formed by the reaction of zirconium with tribromocarboxyarsenazo. The maximum absorption of the complex is at 633 nm, and the apparent molar absorptivity is 4.8 x 10(4) 1/mol/cm. Beer's law is obeyed over the zirconium concentration range 0-18, mug/25 ml. The method has been applied to the determination of zirconium in aluminum, copper and magnesium alloys with satisfactory results. PMID:18965981

Yang, H Y; Zhang, H S; Wang, H

1994-05-01

226

Studies of microstructural imperfections of powdered Zirconium-based alloys  

SciTech Connect

Different model based approaches of X-ray diffraction line profile analysis have been applied on the heavily deformed zirconium-based alloys in the powdered form to characterize the microstructural parameters like domain size, microstrain and dislocation density. In characterizing the microstructure of the material, these methods are complimentary to each other. Though the parameters obtained by different techniques are differently defined and thus not necessarily comparable, the values of domain size and microstrain obtained from the different techniques show similar trends.

Chowdhury, P.S. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India); Sarkar, A. [Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai-400085 (India); Mukherjee, P., E-mail: paramita@vecc.gov.in [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India); Gayathri, N.; Bhattacharya, M.; Barat, P. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata-700 064 (India)

2010-11-15

227

Influence of Temperature on the Dynamic Tensile Behavior of Zirconium  

NASA Astrophysics Data System (ADS)

The influence of temperature on the dynamic tensile behavior of Zr has been investigated. Bullet-shaped Zr samples with two different textures were dynamically extruded at room temperature and 523 K (250 °C). A higher ductility was measured for samples deformed at elevated temperature as compared to those extruded at room temperature. This difference in ductility is discussed in terms of zirconium's ability to accommodate plastic deformation via thermally enhanced slip activity, as evidenced by examination of the deformed microstructures.

Escobedo, Juan P.; Cerreta, Ellen K.; Martinez, Daniel T.; Trujillo, Carl P.; Lebensohn, Ricardo A.; Gray, George T.

2014-12-01

228

Sintering behavior in zirconium phosphate bonded silicon nitride porous ceramics  

Microsoft Academic Search

A new method for preparing high bending strength porous silicon nitride ceramics with controlled porosity has been developed by using a pressureless sintering technique with zirconium phosphate (ZrP2O7) as a binder phase. The sintering behavior in these porous ceramics is investigated in this study by using XRD, SEM, and HRTEM analysis. The results show that the sintering process can be

Fei Chen; Qiang Shen; Julie M. Schoenung; Lianmeng Zhang

2008-01-01

229

The abundances of zirconium and hafnium in the solar system  

Microsoft Academic Search

The concentrations of zirconium and hafnium have been determined in the Orgueil, Murchison, Allende, Bruderheim, and Alais meteorites by radiochemical neutron activation analysis. The mean Zr\\/Hf weight ratio in the first four of these meteorites is 31.3 (plus or minus 2.2), indicating no major fractionation of Zr from Hf. Alais contains anomalously high amounts of many refractory lithophile elements, including

R. Ganapathy; G. M. Papia; LAWRENCE GROSSMAN

1976-01-01

230

Spectrum of Five Times Ionized Zirconium (Zr VI)  

Microsoft Academic Search

We report 279 newly identified transitions of five times ionized zirconium atom (Zr VI) based on recordings made at the 3 m normal incidence spectrograph of Lund University. Thirty-three new energy levels have been established, comprising all the twenty-one levels of 5p configuration, all the nine of 4d that were not known so far, and three of 7s. Previously reported

Zainul Abedeen Khan; M. S. Z. Chaghtai; K. Rahimullah

1981-01-01

231

Trivalent zirconium and hafnium ions in yttrium oxide ceramics  

NASA Astrophysics Data System (ADS)

An analysis of the electron spin resonance (ESR) spectrum of transparent ceramics composed of yttrium oxide with zirconium and hafnium additives has revealed the presence of signals (with similar parameters) from Zr3+ and Hf3+ ions, which have a similar electron configurations of the ground states: [Kr]4 d 1 and [Xe]5 d 1, respectively. It is shown that the pulsed cathodoluminescence spectra of these ions consist of two bands peaking at ? ? 818 and 900 nm.

Solomonov, V. I.; Spirina, A. V.; Konev, S. F.; Cholakh, S. O.

2014-05-01

232

Properties of silicon — Manganese steel with vanadium and zirconium  

Microsoft Academic Search

1.Steel 36G2S with concentrations of carbon and manganese at the lower limit of the range specified does not satisfy the requi rements for the mechanical properties of steel of strength group K for casting pipe (GQST 632-64).2.The addition of small amounts of vanadium and zirconium to medium-carbon silicon-manganese steel increases the strength and ductile characteristics of the steel and ensures

V. N. Zikeev; B. P. Kolesnik; D. A. Litvinenko; V. T. Ababkov; L. I. Guzevataya

1969-01-01

233

Diffusion of Aluminum, Magnesium, Silicon and Zirconium in Nickel  

Microsoft Academic Search

The diffusion rates of aluminum, magnesium, silicon, and zirconium, alloyed as single additives in nickel, have been measured at temperatures between 800°C and 970°C. The method consisted of measuring the weight gain caused by surface oxidation of the additive in a wet hydrogen ambient. The surface oxides were identified by electron diffraction. Grain size was about 0.05 mm in Al&sngbnd;Ni,

Herbert W. Allison; Harold Samelson

1959-01-01

234

A strong ceramic based on aluminum oxide and zirconium dioxide  

Microsoft Academic Search

The theoretical premises and experimental results on fabrication of ceramics based on aluminum oxide with a regulatable structure\\u000a which ensures high strength properties and the possibility of wide use in different areas of technology were reported. The\\u000a effect of adding zirconium oxide to aluminum oxide on the structure and strength properties of the ceramics was demonstrated.\\u000a New ceramic materials having

E. S. Lukin; N. A. Popova; N. I. Zdvizhkova

1993-01-01

235

Polyimide nanocomposites based on cubic zirconium tungstate  

NASA Astrophysics Data System (ADS)

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 extre

Ramasubramanian Sharma, Gayathri

2009-12-01

236

Microbial Uranium Immobilization Independent of Nitrate Reduction  

SciTech Connect

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.

Madden, Andrew [ORNL; Smith, April [Florida State University; Balkwill, Dr. David [Florida State University; Fagan, Lisa Anne [ORNL; Phelps, Tommy Joe [ORNL

2007-01-01

237

Regulation of Nitrate Reductase in Neurospora crassa: Stability In Vivo  

PubMed Central

Nicotinamide adenine dinucleotide phosphate, reduced form (NADPH)-nitrate reductase and its related enzyme activities, NADPH-cytochrome c reductase and reduced benzyl viologen-nitrate reductase, are all induced following the transfer of ammonia-grown wild-type Neurospora mycelia to nitrate medium. After nitrate reductase is induced to the maximal level, the addition of an ammonium salt to, or the removal of nitrate from, the cultures results in a rapid inactivation of nitrate reductase and its two partial component activities. This rapid inactivation is slowed down by the protein synthesis inhibitor, cycloheximide. Experiments on the mixing of extracts in vitro rule out the presence of an inhibitor of nitrate reductase in free form in extracts containing inactivated nitrate reductase. Ammonia does not inhibit the uptake of nitrate by the mycelia. Inactivation of nitrate reductase in vivo by ammonia depends on the concentration of the ammonium salt and is not reversed by increasing the nitrate concentration of the medium. The nitrate-inducible NADPH-cytochrome c reductase activity and reduced benzyl viologen-nitrate reductase activity respectively of the nitrate-nonutilizing mutants nit-1 and nit-3 are not inactivated in vivo by the addition of an ammonium salt or the withdrawal of nitrate. This finding suggests that the integrity of the nitrate reductase complex is required for the in vivo inactivation of nitrate reductase and its associated activities. PMID:4401813

Subramanian, K. N.; Sorger, G. J.

1972-01-01

238

Nitrate(mg/L) Celldensity(10  

E-print Network

0 5 10 15 20 25 30 35 40 45 50 0 5 10 23 29 34 47 53 58 71 77 82 95 101 104 Time (h) Nitrate(mg/L) 0 5 10 15 20 25 30 35 40 45 Celldensity(10 5 cells/ml -1 ) 0 10 20 30 40 0 10 20 30 40 50 Nitrate 50 60 0 10 20 30 40 50 Nitrate(mg/L -1 ) 0 5 10 15 20 25 0 10 20 30 40 50 CellDensity(x105 cells/ml-1

Hall, Sharon J.

239

Photodegradation of Paracetamol in Nitrate Solution  

NASA Astrophysics Data System (ADS)

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.

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

2010-11-01

240

Photodegradation of Paracetamol in Nitrate Solution  

SciTech Connect

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.

Meng Cui; Qu Ruijuan; Liang Jinyan; Yang Xi [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China)

2010-11-24

241

Phase diagram of ammonium nitrate  

SciTech Connect

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.

Dunuwille, Mihindra; Yoo, Choong-Shik, E-mail: csyoo@wsu.edu [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)] [Department of Chemistry and Institute for Shock Physics, Washington State University, Pullman, Washington 99164 (United States)

2013-12-07

242

Qualitative Determination of Nitrate with Triphenylbenzylphosphonium Chloride.  

ERIC Educational Resources Information Center

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)

Berry, Donna A.; Cole, Jerry J.

1984-01-01

243

Original Articles Cytometric Quantification of Nitrate Reductase by  

E-print Network

Original Articles Cytometric Quantification of Nitrate Reductase by Immunolabeling in the Marine November 1999; Accepted 24 November 1999 Background: The uptake of nitrate by phytoplankton is a central of biogenic carbon. Nitrate reductase catalyzes the first step of nitrate assimilation, the reduction of NO3

Jochem, Frank J.

244

The distribution of nitrate 15 N in marine sediments  

E-print Network

The distribution of nitrate 15 N/14 N in marine sediments and the impact of benthic nitrogen loss on the isotopic composition of oceanic nitrate Moritz F. Lehmann a,*, Daniel M. Sigman b , Daniel C. McCorkle c 15 N/14 N ratios of porewater nitrate in sediments from the Bering Sea basin, where microbial nitrate

Sigman, Daniel M.

245

The influence of ammonium on nitrate reduction in wheat seedlings  

Microsoft Academic Search

Ammonium markedly inhibited nitrate absorption by nitrogenstarved wheat seedlings but did not decrease the proportion of absorbed nitrate that was reduced. Seedlings high in nitrate (absorbed prior to the experimental periods) reduced similar amounts of this nitrate regardless of whether or not ammonium was present and being absorbed during the period of measurement. Ammonium or products of ammonium assimilation did

P. L. Minotti; Doris Craig Williams; W. A. Jackson

1969-01-01

246

Materials Science and Engineering A334 (2002) 610 Simulation of g-hydride precipitation in bi-crystalline zirconium  

E-print Network

hot water environment. Zirconium will gradually pick up hydrogen from the hot water environment during June 2001 Abstract The morphology evolution of g-hydride precipitation and growth in a zirconium bi-crystal Elsevier Science B.V. All rights reserved. Keywords: Computer simulation; Zirconium hydride; Bi-crystal

Chen, Long-Qing

247

Structural Basis of Eukaryotic Nitrate Reduction: Crystal Structures of the Nitrate Reductase Active Site  

PubMed Central

Nitrate assimilation in autotrophs provides most of the reduced nitrogen on earth. In eukaryotes, reduction of nitrate to nitrite is catalyzed by the molybdenum-containing NAD(P)H:nitrate reductase (NR; EC 1.7.1.1-3). In addition to the molybdenum center, NR contains iron-heme and flavin adenine dinucleotide as redox cofactors involved in an internal electron transport chain from NAD(P)H to nitrate. Recombinant, catalytically active Pichia angusta nitrate-reducing, molybdenum-containing fragment (NR-Mo) was expressed in P. pastoris and purified. Crystal structures for NR-Mo were determined at 1.7 and 2.6 Å. These structures revealed a unique slot for binding nitrate in the active site and identified key Arg and Trp residues potentially involved in nitrate binding. Dimeric NR-Mo is similar in overall structure to sulfite oxidases, with significant differences in the active site. Sulfate bound in the active site caused conformational changes, as compared with the unbound enzyme. Four ordered water molecules located in close proximity to Mo define a nitrate binding site, a penta-coordinated reaction intermediate, and product release. Because yeast NAD(P)H:NR is representative of the family of eukaryotic NR, we propose a general mechanism for nitrate reduction catalysis. PMID:15772287

Fischer, Katrin; Barbier, Guillaume G.; Hecht, Hans-Juergen; Mendel, Ralf R.; Campbell, Wilbur H.; Schwarz, Guenter

2005-01-01

248

NITRATE DESTRUCTION LITERATURE SURVEY AND EVALUATION CRITERIA  

Microsoft Academic Search

This report satisfies the initial phase of Task WP-2.3.4 Alternative Sodium Recovery Technology, Subtask 1; Develop Near-Tank Nitrate\\/Nitrite Destruction Technology. Some of the more common anions in carbon steel waste tanks at SRS and Hanford Site are nitrate which is corrosive, and nitrite and hydroxide which are corrosion inhibitors. At present it is necessary to periodically add large quantities of

Steimke

2011-01-01

249

Nitrate pollution of groundwater in northern China  

Microsoft Academic Search

Since the 1980s, nitrogen fertiliser consumption in China has increased substantially. High nitrogen application rates may increase the potential groundwater N-pollution. These effects were investigated in 14 cities and counties in northern China. The Merckoquant-nitrate-test strip was used to measure the nitrate concentration in water. Information on well depth, groundwater level, crop rotation, yield and fertiliser application was obtained.The results

W. L. Zhang; Z. X. Tian; N. Zhang; X. Q. Li

1996-01-01

250

The UK Nitrate Time Bomb (Invited)  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

251

Microbial uranium immobilization independent of nitrate reduction.  

PubMed

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

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

2007-09-01

252

Synthesis of a new energetic nitrate ester  

SciTech Connect

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.

Chavez, David E [Los Alamos National Laboratory

2008-01-01

253

Oxidation of pearlitic steels in nitrate solutions  

SciTech Connect

The authors investigated the effect of the temperature, the time of treatment, the concentration, and the pH. They evaluated the protective properties of the oxide films obtained in the treatment of pearlitic steels in nitrate solutions according to the minimal concentration of sodium nitrate necessary for the practically complete suppression of corrosion of the investigated specimens in desalinated water at 20/sup 0/C.

Prozorov, V.V.

1987-11-01

254

Lithium aluminate/zirconium material useful in the production of tritium  

DOEpatents

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.

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

1984-10-09

255

Removal and recovery of zirconium from its aqueous solution by Candida tropicalis  

Microsoft Academic Search

Removal and recovery of zirconium from dilute aqueous solutions by Candida tropicalis used as biosorbent, was studied by performing biosorption–desorption tests. This biosorbent was selected after screening a range of microbial species. The process was found to be highly dependent on initial pH and concentration of metal solution. At optimized experimental parameters, the maximum zirconium biosorption capacity of C. tropicalis

Kalsoom Akhtar; M. Waheed Akhtar; Ahmad M. Khalid

2008-01-01

256

Formation of a zirconium-titanium based conversion layer on AA 6060 aluminium  

Microsoft Academic Search

Structure and chemistry of zirconium-titanium base conversion layers were characterised as a function of immersion time in the aqueous conversion bath to understand the mechanism of film formation. Characterisation was performed by glow discharge optical emission spectroscopy, scanning electron microscopy and transmission electron microscopy. Preferential nucleation of the zirconium-titanium oxide film and its growth occurred on and around intermetallic particles,

J. H Nordlien; J. C Walmsley; H Østerberg; K Nisancioglu

2002-01-01

257

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

258

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

SciTech Connect

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.

Malaestean, Lurie [RWTH Aachen University; Alici, Meliha Kutluca [RWTH Aachen University; Besson, Claire [RWTH Aachen University; Ellern, Arkady [Ames Laboratory; Kogerler, Paul [RWTH Aachen University

2013-10-30

259

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

SciTech Connect

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.

Malaestean, Iurie L. [RWTH Aachen University; Alici, Meliha Kutluca [RWTH Aachen University; Besson, Claire [RWTH Aachen University; Ellern, Arkady [Ames Laboratory; Kogerler, Paul [RWTH Aachen University

2013-10-30

260

Corrosion of Zirconium-based Fuel Cladding Alloys in Supercritical Water. Y.H. Jeong1  

E-print Network

Corrosion of Zirconium-based Fuel Cladding Alloys in Supercritical Water. Y.H. Jeong1 , J.Y. Park1, University Park, PA 16802, USA. Keywords: Zirconium alloys, corrosion, supercritical water Abstract Corrosion to evaluate the potential use of Zr alloy cladding in the supercritical water reactor (SCWR). Corrosion tests

Motta, Arthur T.

261

Inorganic ion-exchangers for the removal of zirconium, hafnium and niobium radioisotopes from aqueous solutions  

Microsoft Academic Search

Studies were made on the uptake of zirconium, hafnium and niobium isotopes onto zeolites and amorphous zirconium phosphate. Ion exchange capacities and distribution coefficients were determined and the influence of pH examined. Kinetic experiments were made to determine the rates of uptake of the radioisotopes on the exchangers and to measure the leaching of isotopes from preloaded exchangers by synthetic

A. Dyer; F. H. Kadhim

1989-01-01

262

Synthesis, Characterization, and Activation of Zirconium and Hafnium Dialkyl Complexes that Contain a  

E-print Network

Synthesis, Characterization, and Activation of Zirconium and Hafnium Dialkyl Complexes that Contain of zirconium and hafnium complexes, [MepyN]MX2 (M ) Zr, X ) NMe2, Cl, OSO2CF3, CH2CHMe2, CH2Ph; M ) Hf, X ) NMe

Müller, Peter

263

Process for separating ceramics of uranium and plutonium from zirconium by hydriding and mixtures thereof  

Microsoft Academic Search

A process is provided involving the use of hydrogen for the separation of uranium and plutonium and mixtures thereof, from composite substances and assemblies or mixtures containing metallic and ceramic components where the metallic component is zirconium or a zirconium alloy and the ceramic component contains uranium and\\/or plutonium.

B. Cech; E. Kaderabek; T. Hanslik

1977-01-01

264

RADIOACTIVE INDICATOR DETERMINATION OF ZIRCONIUM AND PLUTONIUM DOUBLE SULFATES IN SATURATED POTASSIUM SULFATE SOLUTIONS  

Microsoft Academic Search

Zirconium and plutonium double sulfates were prepared by mixing in ; saturated potassium sulfate solution. The data indicate the absence of plutonium ; salt hydrolysis. The compositions of the double sulfates of plutonium(IV) and ; zirconium with potassium bisulf ate prepared under identical conditions are \\/sub ; 3\\/nt, KâPu(SOâ)â and KâZr(SOâ) ). (R. V.J.);

Bobrova

1960-01-01

265

Protein tyrosine nitration in the cell cycle  

SciTech Connect

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.

Jia, Min, E-mail: min.jia@ki.se [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)] [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden); Mateoiu, Claudia; Souchelnytskyi, Serhiy [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)] [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)

2011-09-23

266

Process for decomposing nitrates in aqueous solution  

DOEpatents

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.

Haas, Paul A. (Knoxville, TN)

1980-01-01

267

Differential effect of tungsten on the development of endogenous and nitrate-induced nitrate reductase activities in soybean leaves.  

PubMed

The effect of tungsten on the development of endogenous and nitrate-induced NADH- and FMNH(2)-linked nitrate reductase activities in primary leaves of 10-day-old soybean (Glycine max [L.] Merr.) seedlings was studied. The seedlings were grown with or without exogenous nitrate. High levels of endogenous nitrate reductase activities developed in leaves of seedlings grown without nitrate. However, no endogenous nitrite reductase activity was detected in such seedlings. The FMNH(2)-linked nitrate reductase activity was about 40% of NADH-linked activity. Tungsten had little or no effect on the development of endogenous NADH- and FMNH(2)-linked nitrate reductase activities, respectively. By contrast, in nitrate-grown seedlings, tungsten only inhibited the nitrate-induced portion of NADH-linked nitrate reductase activity, whereas the FMNH(2)-linked activity was inhibited completely. Tungsten had no effect on the development of nitrate-induced nitrite reductase activity. The complete inhibition of FMNH(2)-linked nitrate reductase activity by tungsten in nitrate-grown plants was apparently an artifact caused by the reduction of nitrite by nitrite reductase in the assay system. The results suggest that in soybean leaves either the endogenous nitrate reductase does not require molybdenum or the molybdenum present in the seed is preferentially utilized by the enzyme complex as compared to nitrate-induced nitrate reductase. PMID:16662475

Aslam, M

1982-07-01

268

Differential Effect of Tungsten on the Development of Endogenous and Nitrate-Induced Nitrate Reductase Activities in Soybean Leaves 1  

PubMed Central

The effect of tungsten on the development of endogenous and nitrate-induced NADH- and FMNH2-linked nitrate reductase activities in primary leaves of 10-day-old soybean (Glycine max [L.] Merr.) seedlings was studied. The seedlings were grown with or without exogenous nitrate. High levels of endogenous nitrate reductase activities developed in leaves of seedlings grown without nitrate. However, no endogenous nitrite reductase activity was detected in such seedlings. The FMNH2-linked nitrate reductase activity was about 40% of NADH-linked activity. Tungsten had little or no effect on the development of endogenous NADH- and FMNH2-linked nitrate reductase activities, respectively. By contrast, in nitrate-grown seedlings, tungsten only inhibited the nitrate-induced portion of NADH-linked nitrate reductase activity, whereas the FMNH2-linked activity was inhibited completely. Tungsten had no effect on the development of nitrate-induced nitrite reductase activity. The complete inhibition of FMNH2-linked nitrate reductase activity by tungsten in nitrate-grown plants was apparently an artifact caused by the reduction of nitrite by nitrite reductase in the assay system. The results suggest that in soybean leaves either the endogenous nitrate reductase does not require molybdenum or the molybdenum present in the seed is preferentially utilized by the enzyme complex as compared to nitrate-induced nitrate reductase. PMID:16662475

Aslam, Muhammad

1982-01-01

269

Origin of the deep Bering Sea nitrate deficit: Constraints from the nitrogen and oxygen isotopic composition of water column nitrate  

E-print Network

Origin of the deep Bering Sea nitrate deficit: Constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes Moritz F. Lehmann,1,2 Daniel M. Sigman,1 Daniel. [1] On the basis of the normalization to phosphate, a significant amount of nitrate is missing from

Sigman, Daniel M.

270

Predicting the equilibria of point defects in zirconium oxide : a route to understand the corrosion and hydrogen pickup of zirconium alloys  

E-print Network

The performance of zirconium alloys in nuclear reactors is compromised by corrosion and hydrogen pickup. The thermodynamics and kinetics of these two processes are governed by the behavior of point defects in the ZrO? layer ...

Youssef, Mostafa Youssef Mahmoud

2014-01-01

271

The synthesis and characterization of Zirconium p-Phenylbis(phosphonate) Phosphate and other Zirconium Arylbis(phosphonates) for the application of ion exchange  

E-print Network

. These materials showed promise for many uses, of greatest interest were of catalysis and ion exchange. Zirconium p-Phenylbis(phosphonate) Phosphate was synthesized by several routes to investigate the inherent structural characteristics as they applied...

Bellinghausen, Paul Christian

2012-06-07

272

Control and monitoring of the localized corrosion of zirconium in acidic chloride solutions  

SciTech Connect

Zirconium in acidic chloride solutions which are contaminated with ferric or cupric cations is prone to localized corrosion. This tendency can be reduced by ensuring that the zirconium surface is clean and smooth. In this paper, the effect of surface condition on the localized corrosion of zirconium in acidic chloride solutions is predicted with potentiodynamic scans. These predictions are confirmed by weight loss tests on various combinations of surface finish and acid concentrations. A real time indication of localized corrosion is seen by monitoring the electrochemical noise produced between two similar electrodes immersed in an acidic chloride solutions. Electrochemical noise monitoring correlates well with the predictions from potentiodynamic and weight loss experiments. The electrochemical noise results show that while an elevated (more anodic) potential caused by ferric ion contamination may be a necessary condition for localized corrosion, it is not a sufficient condition: A smooth, clean zirconium surface reduces the localized corrosion of zirconium.

Fahey, J.; Holmes, D.; Yau, T.L. [Teledyne Wah Chang, Albany, OR (United States)

1995-09-01

273

Fundamental studies into zirconium modified phosphonic acid based ionic membranes  

NASA Astrophysics Data System (ADS)

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.

Schlichting, Gregory Joseph

274

The abundances of zirconium and hafnium in the solar system  

NASA Technical Reports Server (NTRS)

The concentrations of zirconium and hafnium have been determined in the Orgueil, Murchison, Allende, Bruderheim, and Alais meteorites by radiochemical neutron activation analysis. The mean Zr/Hf weight ratio in the first four of these meteorites is 31.3 (plus or minus 2.2), indicating no major fractionation of Zr from Hf. Alais contains anomalously high amounts of many refractory lithophile elements, including Zr and Hf. Orgueil contains 3.1 ppm Zr and 0.11 ppm Hf, corresponding to 9.0 and 0.16 atoms, respectively, relative to 1 million Si atoms.

Ganapathy, R.; Papia, G. M.; Grossman, L.

1976-01-01

275

Analysis of irradiation growth in zirconium-base alloy  

NASA Astrophysics Data System (ADS)

Irradiation induced growth phenomena in zirconium-base alloy have been investigated on the basis of the numerical results obtained by dynamical-method computer simulations. Point defect trapping by solute atoms causes transient growth strain which is recoverable during temperature cycling. The growth strain change of cold-worked Zircaloy-2 irradiated at 553 K can be explained by a dislocation climb and a net inflow of vacancies into grain boundaries. The effects of various parameters such as grain size are also discussed.

Fuse, Motomasa

1986-09-01

276

Structure and thermal stability of mesostructured zirconium oxophosphates  

Microsoft Academic Search

Highly ordered mesoporous zirconium oxophosphates (designated as ZOP) with hexagonal P63\\/mmc and cubic Fm3¯m symmetries were firstly prepared by using gemini cationic surfactants as templates. It has been found that the thermal stability was elevated with the structure curvature order: cubic Ia3¯d2D-hexagonalp6mmcubicFm3¯m, hexagonal P63\\/mmc and cubic Pm3¯n. The ZOP mesoporous materials with cubic Fm3¯m and hexagonal P63\\/mmc structures were stable

Yifeng Zhang; Yongsheng Li; Yasuhiro Sakamoto; Osamu Terasaki; Shunai Che

2007-01-01

277

Zirconium(IV) dilanthanum(III) penta­sulfide  

PubMed Central

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

Raw, Adam D.; Ibers, James A.

2011-01-01

278

Suppression of erythropoiesis by dietary nitrate.  

PubMed

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., and Murray, A. J. Suppression of erythropoiesis by dietary nitrate. PMID:25422368

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

2014-11-24

279

Nitrate reductase activity in corn seedlings as affected by light and nitrate content of nutrient media  

Microsoft Academic Search

Young corn plants placed in complete darkness for 48 hours lost 90% of their nitrate reductase activity. The activity was quickly restored when the plants were returned to the light. In other experiments, corn plants were grown under artificial shade in the greenhouse. The nitrate reductase activity in these plants decreased roughly in proportion to the amount of shading. It

R. H. Hageman; D. Flesher

1960-01-01

280

Nitration of naphthalene and remarks on the mechanism of electrophilic aromatic nitration*  

PubMed Central

Naphthalene was nitrated with a variety of nitrating agents. Comparison of data with Perrin's electrochemical nitration [Perrin, C. L. (1977) J. Am. Chem. Soc. 99, 5516-5518] shows that nitration of naphthalene gives an ?-nitronaphthalene to ?-nitronaphthalene ratio that varies between 9 and 29 and is thus not constant. Perrin's data, therefore, are considered to be inconclusive evidence for the proposed one-electron transfer mechanism for the nitration of naphthalene and other reactive aromatics. Moodie and Schoefield [Hoggett, J. G., Moodie, R. B., Penton, J. R. & Schoefield, K. (1971) Nitration and Aromatic Reactivity (Cambridge Univ. Press, London)], as well as Perrin, independently concluded that, in the general scheme of nitration of reactive aromatics, there is the necessity to introduce into the classical Ingold mechanism an additional step involving a distinct intermediate preceding the formation of the Wheland intermediate (? complexes). This view coincides with our two-step mechanistic picture [Kuhn, S. J. & Olah, G. A. (1961) J. Am. Chem. Soc. 83, 4564-4571] of the nitronium salt nitration of aromatic hydrocarbons (including benzene and toluene), in which low substrate selectivity but high positional selectivity was found, indicating the independence of substrate from positional selectivity. PMID:16593026

Olah, George A.; Narang, Subhash C.; Olah, Judith A.

1981-01-01

281

Detection of genes for periplasmic nitrate reductase in nitrate respiring bacteria and in community DNA  

Microsoft Academic Search

A nested PCR primed by four degenerate oligonucleotides was developed for the specific amplification of sequences from the napA gene encoding the periplasmic nitrate reductase. This approach was used to amplify fragments of the napA gene from 10 Pseudomonas species and one Moraxella sp., previously shown to be able to express the periplasmic nitrate reductase activity, from Rhodobacter capsulatus and

Deborah A Flanagan; Lisa G Gregory; Jon P Carter; Asuman Karakas-Sen; David J Richardson; Stephen Spiro

1999-01-01

282

Quantification of nitrate sources to an urban stream using dual nitrate isotopes.  

PubMed

Human-engineered landscapes and subsequent altered hydrology affect the fate and transport of reactive nitrogen, particularly in urban watersheds. In this study, we used dual-nitrate isotopes and mixing model analysis (?(15)N and ?(18)O of NO3(-)) to quantify nitrogen inputs from two sources concentrated in urban systems, sewage and atmospheric deposition. Analysis was conducted on samples collected from Nine Mile Run (Pittsburgh, PA) including over two years of samples collected biweekly and samples collected through the hydrographs of four storm events. Mixing models incorporated uncertainties in the isotopic composition of potential nitrate sources and resolved the relative proportions of nitrate inputs from each source using Bayesian techniques. The results indicate that up to 94% of nitrate in streamwater originated from sewage sources during baseflow conditions. During storms, atmospheric deposition was a substantial nitrate source (? 34%) to total event-based nitrate loads, although sewage-derived nitrate remained the dominant source (66%). The potential influence of denitrification was considered by incorporating associated isotopic fractionations into mixing models; up to 19% of sewage-derived samples showed the isotopic effects of denitrification. This study quantitatively delineates proportions of nitrate from different sources to urban streamwater, while incorporating remaining uncertainties in source endmember compositions. PMID:25134416

Divers, Marion T; Elliott, Emily M; Bain, Daniel J

2014-09-16

283

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...

284

Origin of the deep Bering Sea nitrate deficit: Constraints from the nitrogen and oxygen isotopic composition of water column nitrate and benthic nitrate fluxes  

Microsoft Academic Search

On the basis of the normalization to phosphate, a significant amount of nitrate is missing from the deep Bering Sea (BS). Benthic denitrification has been suggested previously to be the dominant cause for the BS nitrate deficit. We measured water column nitrate 15N\\/14N and 18O\\/16O as integrative tracers of microbial denitrification, together with pore water-derived benthic nitrate fluxes in the

Moritz F. Lehmann; Daniel M. Sigman; Daniel C. McCorkle; Brigitte G. Brunelle; Sharon Hoffmann; Markus Kienast; Greg Cane; Jaclyn Clement

2005-01-01

285

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

PubMed Central

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

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

2012-01-01

286

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

PubMed Central

• 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

POONNACHIT, U.; DARNELL, R.

2004-01-01

287

In Vivo Assay of Nitrate Reductase in Cotton Leaf Discs  

PubMed Central

Factors affecting nitrate reduction by leaf discs of cotton (Gossypium hirsutum L.) were investigated. When incubated in 30 mm nitrate, discs reduced nitrate much more slowly under air or O2 than under N2. Inhibition by O2 did not occur at nitrate levels of 100 mm or greater. Treatment with arsenate had little effect under N2 but stimulated nitrate reduction under air. Similarly, ammonium inhibited nitrate reduction, with the inhibition being partially relieved by arsenate. Uptake of nitrate was unaffected by ammonium. The NAD/NADH ratio increased in response to both oxygen and ammonium. The effects of these treatments on nitrate reduction can be explained by competition with nitrate for NADH generated by glycolysis. PMID:16658325

Radin, J. W.

1973-01-01

288

Molecular components of nitrate and nitrite efflux in yeast.  

PubMed

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

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

2014-02-01

289

Molecular Components of Nitrate and Nitrite Efflux in Yeast  

PubMed Central

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

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

2014-01-01

290

Vulnerability of streams to legacy nitrate sources  

USGS Publications Warehouse

The influence of hydrogeologic setting on the susceptibility of streams to legacy nitrate was examined at seven study sites having a wide range of base flow index (BFI) values. BFI is the ratio of base flow to total streamflow volume. The portion of annual stream nitrate loads from base flow was strongly correlated with BFI. Furthermore, dissolved oxygen concentrations in streambed pore water were significantly higher in high BFI watersheds than in low BFI watersheds suggesting that geochemical conditions favor nitrate transport through the bed when BFI is high. Results from a groundwater-surface water interaction study at a high BFI watershed indicate that decades old nitrate-laden water is discharging to this stream. These findings indicate that high nitrate levels in this stream may be sustained for decades to come regardless of current practices. It is hypothesized that a first approximation of stream vulnerability to legacy nutrients may be made by geospatial analysis of watersheds with high nitrogen inputs and a strong connection to groundwater (e.g., high BFI).

Tesoriero, Anthony J.; Du?, John H.; Saad, David A.; Spahr, Norman E.; Wolock, David M.

2013-01-01

291

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

PubMed

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

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

2015-01-28

292

Hydrogen pickup measurements in zirconium alloys: Relation to oxidation kinetics  

NASA Astrophysics Data System (ADS)

The optimization of zirconium-based alloys used for nuclear fuel cladding aims to reduce hydrogen pickup during operation, and the associated cladding degradation. The present study focuses on precisely and accurately measuring hydrogen pickup fraction for a set of alloys to specifically investigate the effects of alloying elements, microstructure and corrosion kinetics on hydrogen uptake. To measure hydrogen concentrations in zirconium alloys two techniques have been used: a destructive technique, Vacuum Hot Extraction, and a non-destructive one, Cold Neutron Prompt Gamma Activation Analysis. The results of both techniques show that hydrogen pickup fraction varies significantly with exposure time and between alloys. A possible interpretation of the results is that hydrogen pickup results from the need to balance charge. That is, the pickup of hydrogen shows an inverse relationship to oxidation kinetics, indicating that, if transport of charged species is rate limiting, oxide transport properties such as oxide electronic conductivity play a key role in the hydrogen pickup mechanism. Alloying elements (either in solid solution or in precipitates) would therefore impact the hydrogen pickup fraction by affecting charge transport.

Couet, Adrien; Motta, Arthur T.; Comstock, Robert J.

2014-08-01

293

Zirconium speciation in lactate solutions and polyacrylate gels.  

PubMed

Controlling gelation kinetics is an important objective for several applications (ceramic and thin film syntheses, reduction in permeability of porous rock, etc). There is a growing interest in studying the gelation of polymers by zirconium, a crosslinker of lower toxicity than the chromium which is still commonly used. XAS at the Zr K-edge was performed at the European Synchrotron Radiation Facility (ESRF) on the BM32 beamline. The fluorescence detection was used to carry out successful in situ speciation at concentrations as low as 36 ppm. The Zr speciation was determined both in ZrLa (where La stands for lactate) aqueous solutions and in gels of a terpolymer of acrylamide having 2% of zirconium reactive acrylate side groups and 2% of sulfonate groups introduced to prevent syneresis. XANES results show that Zr is always in a dodecahedral geometry. In ZrLa solutions. EXAFS results indicate that Zr species grow from a dimer Zr2(La)6 to a tetramer (Zr4(La)x) and then to larger polymers resulting from tetramer associations, as the Zr concentration decreases from 51840 ppm to 36ppm. In polymer gels, Zr species appear to be dimers at pH 6 while tetramers are found when gelation occurred at pH 7. Calculations taking into account multiple scattering effects as well as dynamic molecular calculation confirmed conclusions derived from conventional EXAFS analysis. PMID:11512896

Rose, J; Chauveteau, G; Tabary, R; Renard, M; Omari, A; Toulhoat, H

2001-03-01

294

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

295

Kinetics of Nitrate Utilization by Mixed Populations of Denitrifying Bacteria †  

PubMed Central

Kinetics of nitrate utilization by mixed bacterial populations from two agricultural soils and a pond sediment in Kentucky were measured by using progress curves of nitrous oxide production. Nitrous oxide production from anaerobic soil and sediment slurries containing added nitrate and acetylene exhibited first-order kinetics. Nitrate affinity (Km) for mixed populations of denitrifying bacteria in unfertilized agricultural soils and pond sediments ranged from 1.8 to 13.7 ?M. The affinity of bacterial populations for nitrate did not vary with habitat, and the ability to use low concentrations of nitrate was retained by bacterial populations living in environments which received large inputs of nitrate. PMID:16347879

Murray, Robert E.; Parsons, Laura L.; Smith, M. Scott

1989-01-01

296

Techniques for Measurement of Nitrate Movement in Soils  

NASA Technical Reports Server (NTRS)

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.

Broadbent, F. E.

1971-01-01

297

Measuring Nitrates and Their Effect on Water Quality  

NSDL National Science Digital Library

This module on measuring nitrates and their effects on water quality is from a larger series on water quality investigations. It provides background information on nitrates and how it affects water quality. It also contains both a pre-test and post-test, a laboratory investigation, and a self-study game. The purpose of the site is to help students understand the sources of nitrates and the role that nitrates play in an ecosystem, describe the effects of excess nitrates on water quality and human health, and teach students how to measure, graph, and interpret the direct and indirect effects of nitrates on fish.

Johnson, Larry

298

Organic nitrates: past, present and future.  

PubMed

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

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

2014-01-01

299

Direct observation of zirconium segregation to dislocations and grain boundaries in NiAl  

SciTech Connect

Segregation of zirconium to dislocations in microalloyed NiAl has been directly observed in the atom probe field ion microscopy (APFIM). Approximately two thirds of the <100> dislocations in the NiAl matrix exhibited zirconium segregation. Zirconium-rich regions with ribbon-like morphology were also detected in the NiAl matrix. It is suggested that these regions are associated with dislocations. These results support the suggestion that the substantial increase in ductile-to-brittle transition temperature (DBTT) of the zirconium-doped alloy is due to pinning of dislocations by zirconium. Since the mechanism underlying the DBTT in binary NiAl is not understood, it would be of interest to examine the possibility of a similar pinning of dislocations by trace interstitial and other impurities in the undoped alloy. Segregation of zirconium to grain boundaries has also been observed in the APFIM. This result indicates the possible strengthening of grain boundaries has also been observed in the APFIM. This result indicates the possible strengthening of grain boundaries due to zirconium segregation and is consistent with the change in the fracture mode from intergranular in the undoped NiAl to a mixture of intergranular and transgranular mode in zirconium-doped NiAl. The NiAl matrix was heavily depleted of both solutes molybdenum and zirconium. Small Mo-rich precipitates observed in the matrix and at grain boundaries and the ribbon-like Zr-rich regions are likely to contributed to the increase in yield stress through precipitation hardening.

Jayaram, R. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering] [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Miller, M.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Division] [Oak Ridge National Lab., TN (United States). Metals and Ceramics Division

1995-07-01

300

Nitrate postdeposition processes in Svalbard surface snow  

NASA Astrophysics Data System (ADS)

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 ?(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 ?(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.

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

301

Electrolytic removal of nitrate from crop residues.  

PubMed

The Controlled Ecological Life Support System (CELSS) resource recovery system, which is a waste-processing system,uses aerobic and anaerobic bioreactors to recover plants nutrients and secondary foods from the inedible biomass. Crop residues contain a significant amount of nitrate. There are actually two major problems concerning nitrate: 1) both CELSS biomass production and resource recovery consume large quantities of nitric acid, and 2) nitrate causes a variety of problems in both aerobic and anaerobic bioreactors. The nitrate anion causes several problems in the resource recovery system in such a way that removal prior to the process is highly desirable. The technique proposed to remove nitrate from potato inedible biomass leachate and to satisfy the nitric acid demand was a four-compartment electrolytic cell. In order to establish the electrolytic cell performance variables, experiments were carried out using potato crop residue aqueous leachate as the diluate solution. The variables studied were the potato biomass leachate composition and electrical properties, preparation of compartment solutions to be compatible with the electrolytic system, limiting current density, nutrients removal rates as a function of current density, fluid hydrodynamic conditions, applied voltage, and process operating time during batch recirculation operation. Results indicated that the limiting current density (maximum operating current density) was directly proportional to the solution electrical conductivity an a power function of the linear fluid velocity in the range between 0.083 and 0.403 m/s. During the electrolytic cell once-through operation, the nitrate, potassium, and other nutrient removal rates were proportional to the current density and were inversely proportional to fluid velocity. The removal of monovalent ions was found to be higher than divalent ones. Under batch recirculation operation at constant applied voltage of 4.5 and 8.5 V, it was found that the nutrient removal rates were independent of applied voltage, but were proportional to the ions concentration and operating time. PMID:11676458

Colon, G; Sager, J C

2001-01-01

302

Dietary nitrate in man: friend or foe?  

PubMed

Based on the premise that dietary nitrate is detrimental to human health, increasingly stringent regulations are being instituted to lower nitrate levels in food and water. Not only does this pose a financial challenge to water boards and a threat to vegetable production in Northern Europe, but also may be eliminating an important non-immune mechanism for host defence. Until recently nitrate was perceived as a purely harmful dietary component which causes infantile methaemoglobinaemia, carcinogenesis and possibly even teratogenesis. Epidemiological studies have failed to substantiate this. It has been shown that dietary nitrate undergoes enterosalivary circulation. It is recirculated in the blood, concentrated by the salivary glands, secreted in the saliva and reduced to nitrite by facultative Gram-positive anaerobes (Staphylococcus sciuri and S. intermedius) on the tongue. Salivary nitrite is swallowed into the acidic stomach where it is reduced to large quantities of NO and other oxides of N and, conceivably, also contributes to the formation of systemic S-nitrosothiols. NO and solutions of acidified nitrite, mimicking gastric conditions, have been shown to have antimicrobial activity against a wide range of organisms. In particular, acidified nitrite is bactericidal for a variety of gastrointestinal pathogens such as Yersinia and Salmonella. NO is known to have vasodilator properties and to modulate platelet function, as are S-nitrosothiols. Thus, nitrate in the diet, which determines reactive nitrogen oxide species production in the stomach (McKnight et al. 1997), is emerging as an effective host defence against gastrointestinal pathogens, as a modulator of platelet activity and possibly even of gastrointestinal motility and microcirculation. Therefore dietary nitrate may have an important therapeutic role to play, not least in the immunocompromised and in refugees who are at particular risk of contracting gastroenteritides. PMID:10615207

McKnight, G M; Duncan, C W; Leifert, C; Golden, M H

1999-05-01

303

9-Amino­acridinium nitrate monohydrate  

PubMed Central

The pyridine N atom of the cation in the title hydrated salt, C13H11N2 +·NO3 ?·H2O, is protonated; the N atom of the NH2 group shows a planar conformation. The former N atom is hydrogen bonded to a water mol­ecule. The amino group is involved in three N—H?O hydrogen bonds with two neighboring nitrate anions. The water mol­ecule is hydrogen bonded to two adjacent nitrate anions. In the crystal, this results in a layered network. PMID:21522328

Pourayoubi, Mehrdad; Eshtiagh-Hosseini, Hossein; Sanaei Ataabadi, Somayyeh; Mancilla Percino, Teresa; A. Leyva Ramírez, Marco

2011-01-01

304

A Reservoir of Nitrate Beneath Desert Soils  

USGS Publications Warehouse

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.

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

2003-01-01

305

Methylhydrazinium nitrate. [rocket plume deposit chemistry  

NASA Technical Reports Server (NTRS)

Methylhydrazinium nitrate was synthesized by the reaction of dilute nitric acid with methylhydrazine in water and in methanol. The white needles formed are extremely hygroscopic and melt at 37.5-40.5 C. The IR spectrum differs from that reported elsewhere. The mass spectrum exhibited no parent peak at 109 m/z, and thermogravimetric analysis indicated that the compound decomposed slowly at 63-103 C to give ammonium and methylammonium nitrate. The density is near 1.55 g/cu cm.

Lawton, E. A.; Moran, C. M.

1983-01-01

306

Histopathological and microanalytical study of zirconium dioxide and barium sulphate in bone cement.  

PubMed Central

AIMS: To report the appearances of zirconium dioxide and barium sulphate in interface membranes, synovium, and other tissues around joint prostheses. METHODS: Histological sections from 23 specimens were reviewed by light microscopy and polarisation. Scanning electron microscopy and x ray microanalysis were performed on routinely processed paraffin wax sections. RESULTS: Polyethylene, metals, and polymethylmethacrylate cement debris were easily recognisable. Almost all the cement remnants contained either zirconium dioxide or barium sulphate, confirmed by microanalysis. The contrast media had characteristic light microscopic appearances. Zirconium was identified in macrophages away from cement remnants. CONCLUSION: The presence of radiographic contrast media in tissues around prosthetic joints is common but not widely recognised. Images PMID:1452794

Keen, C. E.; Philip, G.; Brady, K.; Spencer, J. D.; Levison, D. A.

1992-01-01

307

A NOVEL LAYERED ZIRCONIUM PHOSPHATE Zr2O3(HPO4). SYNTHESIS AND CHARACTERIZATION OF PROPERTIES  

Microsoft Academic Search

Several novel crystalline layered zirconium phosphates with composition Zr2O3(HPO4)-nH2O (M=Na, K) were prepared by the partial hydrolytic decomposition of amorphous or crystalline a-zirconium phosphates in alkaline media under mild hydrothermal conditions. The corresponding Li-and Cs-forms of this phosphate were obtained by successive treatment of Na- or K-forms with LiOH or CsOH solutions. Two hydrogen forms of the novel zirconium phosphate

Anatoly I. Bortun; Lyudmila N. Bortun; Abraham Clearfield

1997-01-01

308

Physicomechanical properties of the surface of a zirconium alloy modified by a pulsed ion beam  

NASA Astrophysics Data System (ADS)

The physicomechanical properties of the surface of the Zr-1% Nb zirconium alloy modified by a pulsed carbon ion beam with a pulse duration of 80 ns, an energy of 200 keV, and a current density of 120 A/cm2 are studied at four regimes having different numbers of pulses. Irradiation by a carbon ion beam results in hardening of the surface layer to a depth of 2 ?m, grain refinement to 0.15-0.8 ?m, zirconium carbide formation, and a decrease in the hydrogen permeability of the zirconium alloy.

Chernov, I. P.; Berezneeva, E. V.; Beloglazova, P. A.; Ivanova, S. V.; Kireeva, I. V.; Lider, A. M.; Remnev, G. E.; Pushilina, N. S.; Cherdantsev, Yu. P.

2014-04-01

309

The effect of purity on high-temperature oxidation of zirconium  

SciTech Connect

The oxidation kinetics of zirconium of different purities were studied over the temperature range of 600-1300[degrees]C ([alpha]- and [beta]-phases). The structure of the oxidized specimens was examined. TGA, XRD, EPMA, SEM, metallographic analysis, and microhardness measurements were carried out. Impurity elements were found to increase the oxidation rate of technical zirconium. The mechanism of the effect of impurity elements on zirconium oxidation was shown to differ for the [alpha]- and [beta]-phases. Activation energies were calculated for the parabolic and linear stages of oxidation.

Voitovich, V.B.; Lavrenko, V.A.; Voitovich, R.F.; Golovko, E.I. (Institute for Problems of Material Science, Kiev (Ukraine))

1994-10-01

310

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

311

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

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

312

Nitrate Reductase and Soluble Cytochrome c in Spirillum itersonii  

PubMed Central

The addition of nitrate to cultures of Spirillum itersonii incubated under low aeration produced a diauxic growth pattern in which the second exponential phase was preceded by the appearance of nitrite in the medium. The organism also grew anaerobically in the presence of nitrate. Nitrate reductase activity could be demonstrated in cell-free extracts by use of reduced methyl viologen as the electron donor. The enzyme was located in the supernatant fraction after centrifugation of extracts for 2 hr at 40,000 × g, and it sedimented as a single peak when centrifuged in a sucrose gradient. Nitrate reductase activity was found in cells grown with low aeration without nitrate, but was increased about twofold by addition of nitrate. Enzyme activity was negligible in cells grown with high aeration. The proportion of soluble cytochrome c was increased two- to threefold in cells grown with nitrate. The specific activities of nitrate reductase and soluble cytochrome c rose when nitrate or nitrite was added to cell suspensions incubated with low aeration; nitrite was more effective than nitrate during the early stages of incubation. A nitrate reductase-negative mutant synthesized increased amounts of soluble cytochrome c in response to nitrate or to nitrite in the cell suspension system. It is concluded that enhanced synthesis of soluble cytochrome c does not require the presence of a functional nitrate reductase. PMID:5429724

Gauthier, Dorothy K.; Clark-Walker, G. D.; Garrard, W. T.; Lascelles, June

1970-01-01

313

COGEMA Experience in Uranous Nitrate Preparation  

SciTech Connect

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)

Tison, E. [COGEMA, AREVA Group, Etablissement de La Hague, 50440 Beaumont La Hague Cedex (France); Bretault, Ph. [SGN, AREVA Group, 1 rue des Herons, 78182 St Quentin Yvelines Cedex (France)

2006-07-01

314

Perchlorate and nitrate in situ bioremediation of ground water  

SciTech Connect

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.

Strietelmeier, E. A. (Elizabeth A.); Nuttall, H. Eric; Hatzinger, Paul; Goltz, Mark

2002-01-01

315

Investigation of desert subsoil nitrate in Northeastern Badia of Jordan.  

PubMed

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

Al-Taani, Ahmed A; Al-Qudah, Khaldoun A

2013-01-01

316

CURRENT METHODS TO MEASURE ATMOSPHERIC NITRIC ACID AND NITRATE ARTIFACTS  

EPA Science Inventory

Presentations given at a workshop on 'Measurement of Atmospheric Nitrates' (Southern Pines, N.C. October 3-4, 1978) are documented. The authors consider various analytical methods to measure ambient concentrations of nitric acid and artifact nitrate formation....

317

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2012 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2012-10-01

318

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2011 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2011-10-01

319

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2014 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2014-10-01

320

46 CFR 148.220 - Ammonium nitrate-phosphate fertilizers.  

Code of Federal Regulations, 2013 CFR

...false Ammonium nitrate-phosphate fertilizers. 148.220 Section 148.220 ...220 Ammonium nitrate-phosphate fertilizers. (a) This section applies to...phosphate or nitrogen/potash type fertilizers, or complete fertilizers of...

2013-10-01

321

Light-Dark Changes in Cytosolic Nitrate Pools Depend on Nitrate Reductase Activity in Arabidopsis Leaf Cells1[w  

PubMed Central

Several different cellular processes determine the size of the metabolically available nitrate pool in the cytoplasm. These processes include not only ion fluxes across the plasma membrane and tonoplast but also assimilation by the activity of nitrate reductase (NR). In roots, the maintenance of cytosolic nitrate activity during periods of nitrate starvation and resupply (M. van der Leij, S.J. Smith, A.J. Miller [1998] Planta 205: 64–72; R.-G. Zhen, H.-W. Koyro, R.A. Leigh, A.D. Tomos, A.J. Miller [1991] Planta 185: 356–361) suggests that this pool is regulated. Under nitrate-replete conditions vacuolar nitrate is a membrane-bound store that can release nitrate to the cytoplasm; after depletion of cytosolic nitrate, tonoplast transporters would serve to restore this pool. To study the role of assimilation, specifically the activity of NR in regulating the size of the cytosolic nitrate pool, we have compared wild-type and mutant plants. In leaf mesophyll cells, light-to-dark transitions increase cytosolic nitrate activity (1.5–2.8 mm), and these changes were reversed by dark-to-light transitions. Such changes were not observed in nia1nia2 NR-deficient plants indicating that this change in cytosolic nitrate activity was dependent on the presence of functional NR. Furthermore, in the dark, the steady-state cytosolic nitrate activities were not statistically different between the two types of plant, indicating that NR has little role in determining resting levels of nitrate. Epidermal cells of both wild type and NR mutants had cytosolic nitrate activities that were not significantly different from mesophyll cells in the dark and were unaltered by dark-to-light transitions. We propose that the NR-dependent changes in cytosolic nitrate provide a cellular mechanism for the diurnal changes in vacuolar nitrate storage, and the results are discussed in terms of the possible signaling role of cytosolic nitrate. PMID:15908593

Cookson, Sarah J.; Williams, Lorraine E.; Miller, Anthony J.

2005-01-01

322

Assimilatory Nitrate Reduction in Hansenula polymorpha  

NASA Astrophysics Data System (ADS)

In the last decade, the yeast Hansenula polymorpha (syn.: Pichia angusta) has become an excellent experimental model for genetic and molecular investigations of nitrate assimilation, a subject traditionally investigated in plants, filamentous fungi and bacteria. Among other advantages, H. polymorpha offers classical and molecular genetic tools, as well as the availability of genomic sequence data.

Rossi, Beatrice; Berardi, Enrico

323

Spatial Inference of Nitrate Concentrations in Groundwater  

E-print Network

Spatial Inference of Nitrate Concentrations in Groundwater DAWN B. WOODARD, ROBERT L. WOLPERT in groundwater over the mid-Atlantic states, using measurements gathered during a pe- riod of ten years. A map- trations in air, pesticide concentrations in groundwater, or any other quantity that varies over

West, Mike

324

21 CFR 172.170 - Sodium nitrate.  

Code of Federal Regulations, 2014 CFR

... (1) As a preservative and color fixative, with or without sodium nitrite, in smoked, cured sablefish, smoked, cured salmon, and smoked, cured shad, so that the level of sodium nitrate does not exceed 500 parts per million and the level of...

2014-04-01

325

Denitration of High Nitrate Salts Using Reductants  

SciTech Connect

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).

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

1999-05-03

326

Negative ion spectrometry for detecting nitrated explosives  

NASA Technical Reports Server (NTRS)

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.

Boettger, H. G.; Yinon, J.

1975-01-01

327

76 FR 46907 - Ammonium Nitrate Security Program  

Federal Register 2010, 2011, 2012, 2013, 2014

...CBSNews.com, Fertilizer Used in Terror Bombs (Apr. 14, 2004), http...ammonium nitrate can be effectively used in bomb-making. By proposing to include a mixture...under this rule mixtures that terrorist bomb-makers would be most interested in...

2011-08-03

328

Iron, nitrate uptake by phytoplankton, and mermaids  

Microsoft Academic Search

The critque 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.

Karl Banse

1991-01-01

329

Ceric ammonium nitrate promoted oxidation of oxazoles.  

PubMed

The ceric ammonium nitrate promoted oxidations of 4,5-diphenyloxazoles and oxazoles with various substitution patterns have been investigated. This transformation results in the formation of the corresponding imide in good yield and tolerates a wide variety of functional groups and substituents on the oxazole moiety. [reaction: see text]. PMID:17107099

Evans, David A; Nagorny, Pavel; Xu, Risheng

2006-11-23

330

Benchmark Evaluation of Plutonium Nitrate Solution Arrays  

Microsoft Academic Search

In October and November of 1981 thirteen approach-to-critical experiments were performed on a remote split table machine (RSTM) in the Critical Mass Laboratory of Pacific Northwest Laboratory (PNL) in Richland, Washington, using planar arrays of polyethylene bottles filled with plutonium (Pu) nitrate solution. Arrays of up to sixteen bottles were used to measure the critical number of bottles and critical

M. A. Marshall; J. D. Bess

2011-01-01

331

Characterization of nitrate reductase from the yeast Candida utilis  

Microsoft Academic Search

The assimilatory nitrate reductase [NAD (P) H: nitrate oxidoreductase, EC 1.6.6.2] of the nitrate-utilizing yeastCandida utilis was prepared in soluble form from cells grown aerobically with nitrate as the nitrogen source, and some of its properties\\u000a studied. The enzyme is cytoplasmic in intracellular distribution and its activity is NAD (P) H-dependent. The enzyme utilized\\u000a both NADH and NADPH as electron

V. Prabhakara Choudary; G. Ramananda Rao

1976-01-01

332

Evidence for a plasma-membrane-bound nitrate reductase involved in nitrate uptake of Chlorella sorokiniana  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

333

Separation of Zirconium from Uranium in U-Zr Alloys Using a Chlorination Process  

E-print Network

The fundamental behavior underpinning a new processing concept was demonstrated which is capable of separating uranium from zirconium in U-Zr alloys through the formation and selective volatilization of their respective chlorides. Bench...

Parkison, Adam J

2013-06-04

334

JOURNAL OF MATERIALS SCIENCE 36 (2001) 77 86 Synthesis of yttria-doped strontium-zirconium  

E-print Network

JOURNAL OF MATERIALS SCIENCE 36 (2001) 77­ 86 Synthesis of yttria-doped strontium-zirconium oxide densification, than co-precipitated powders. C 2001 Kluwer Academic Publishers 1. Introduction Strontium

Iglesia, Enrique

335

Electrochemical formation of uranium-zirconium alloy in LiCl-KCl melts  

NASA Astrophysics Data System (ADS)

Since zirconium is considered an electrochemically active species under practical conditions of the electrorefining process, it is crucial to understand the electrochemical behavior of zirconium in LiCl-KCl melts containing actinide ions. In this study, the electrochemical codeposition of uranium and zirconium on a solid cathode was performed. It was found that the ?-(U, Zr) phase, which is the only intermediate phase of the uranium-zirconium binary alloy system, was deposited on a tantalum substrate by potentiostatic electrolysis at -1.60 V (vs. Ag +/Ag) in LiCl-KCl melts containing 0.13 in mol% UCl 3 and 0.23 in mol% ZrCl 4 at 773 K. To our knowledge, this is the first report on the electrochemical formation of the ?-(U, Zr) phase. The relative partial molar properties of uranium in the ?-(U, Zr) phase were evaluated by measuring the open-circuit-potentials of the electrochemically prepared ?-phase electrode.

Murakami, Tsuyoshi; Kato, Tetsuya; Kurata, Masaki; Yamana, Hajimu

2009-11-01

336

Development of a plasma coating system for induction melting zirconium in a graphite crucible  

SciTech Connect

A plasma coating system has been developed for induction melting zirconium at 1900 C using a graphite crucible. This laminated coating system consists of plasma spraying the following materials onto the graphite: (1) molybdenum or tungsten, (2) a 50% blend by weight of the metal powder and calcia-stabilized zirconium oxide, and (3) calcia-stabilized zirconia followed by painting a final coating of nonstabilized zirconia on top of the plasma-sprayed coating system. Zirconium was melted in argon using both laminating systems without any degradation of the graphite crucible and with only a minimal amount of carbon absorption. This novel approach that is being proposed as an alternative method of melting zirconium alloys offers substantial cost savings over the standard practice of electric arc melting using a consumable electrode.

Bird, E.L.; Holcombe, C.E. Jr.

1993-05-26

337

Structure of zirconium-rich alloys of the Zr-Ru system  

NASA Astrophysics Data System (ADS)

The equilibrium and metastable phases of zirconium-rich binary alloys of the Zr-Ru system are studied experimentally. Maximum solubility of ruthenium is found to equal 11 at.% in beta-zirconium at the eutectic temperature of 1250 C, and about 1 at.% in alpha-zirconium at 600 C. Ruthenium is shown to reduce the zirconium reversible alpha-beta transformation temperature. Eutectoid decomposition of beta-solid solution was not observed at temperatures up to 600 C. In alloys quenched from 1000 to 800 C, the omega-phase was found with the following lattice periods: a = 4.997, c = 3.134 A, and c/a = 0.627.

Eremenko, V. N.; Semenova, E. L.; Shtepa, T. D.

1980-04-01

338

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

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Use of aerosol cosmetic products containing zirconium. 700.16...HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol...

2010-04-01

339

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

Code of Federal Regulations, 2011 CFR

... 2010-04-01 true Use of aerosol cosmetic products containing zirconium. 700.16...HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.16 Use of aerosol...

2011-04-01

340

Engineering analysis of low enriched uranium fuel using improved zirconium hydride cross sections  

E-print Network

. All of these simulations used improved zirconium hydride cross sections that were provided by Dr. Ayman Hawari at North Carolina State University. The neutronic and thermal analysis showed that the reactor will operate with approximately the same fuel...

Candalino, Robert Wilcox

2006-10-30

341

Methods for Investigating Gas Bubble Formation in Uranium-Zirconium Alloys  

E-print Network

Uranium-zirconium alloy nuclear fuels have many advantages as compared with ceramic fuels, especially for fast reactor systems. However, metallic fuels aren’t currently used in commercial power production due in part to issues with fuel swelling...

Mews, Kathryn Ann Wright

2013-05-06

342

Cation-exchange separation of hafnium and zirconium from accompanying ions.  

PubMed

Hafnium and zirconium are not retained on the strongly acidic cation-exchange resin Dowex 50 from a mixture consisting of methanol and 12M nitric acid (19:1) which is 0.1M in trioctylphosphine oxide. On the other hand most other elements investigated are strongly adsorbed on the resin from this medium so that they are readily separated from hafnium and zirconium. These elements include titanium, rare earths, alkali metals, alkaline earth metals, iron, cobalt, manganese and zinc. This separation technique has been found to be suitable for the separation of tracer and milligram amounts of hafnium and zirconium from accompanying metal ions. If in place of methanol other organic solvents such as acetone, tetrahydrofuran and methyl glycol are used the selectivity of the separation of zirconium and hafnium from the other elements is decreased. The same effect is observed when hydrochloric acid is used in the mixtures instead of nitric acid. PMID:18960465

Korkisch, J; Orlandini, K A

1969-01-01

343

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...

344

Enhancement of nitrate reductase activity by benzyladenine in Agrostemma githago  

Microsoft Academic Search

Nitrate reductase activity in excised embryos of Agrostemma githago increases in response to both NOâ⁻ and cytokinins. Discussed was whether cytokinins affected nitrate reductase activity directly or through NOâ⁻, either by amplifying the effect of low endogenous NOâ⁻ levels, or by making NOâ⁻ available for induction from a metabolically inactive compartment. Nitrate reductase activity was enhanced on the average by

H. Kende; H. Hahn; S. E. Kays

1971-01-01

345

9 CFR 319.2 - Products and nitrates and nitrites.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Products and nitrates and nitrites. 319.2 Section 319... General § 319.2 Products and nitrates and nitrites. Any product, such...is a standard in this part and to which nitrate or nitrite is permitted or required...

2012-01-01

346

Introduction Current methods to determine nitrate (NO3  

E-print Network

205 Introduction Current methods to determine nitrate (NO3 ­ ) nitrogen (N) and oxygen (O) isotope of nitrate versus that of nitrite in a given sample. In the case of the ammonia distillation (Cline and Kaplan 1975) and ammonia diffusion (Sigman et al. 1997) methods for nitrate N isotope analysis, both

Sigman, Daniel M.

347

9 CFR 319.2 - Products and nitrates and nitrites.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Products and nitrates and nitrites. 319.2 Section 319... General § 319.2 Products and nitrates and nitrites. Any product, such...is a standard in this part and to which nitrate or nitrite is permitted or required...

2011-01-01

348

Turbulent nitrate fluxes in the Amundsen Gulf during icecovered conditions  

E-print Network

Turbulent nitrate fluxes in the Amundsen Gulf during icecovered conditions D. Bourgault,1 C. Hamel; revised 21 June 2011; accepted 23 June 2011; published 2 August 2011. [1] Turbulence and nitrate mean vertical profiles of eddy diffusivity K and diffusive nitrate fluxes F. The mean diffusivity (with

349

Quantifying Nitrate Flux during Storm Events J. S. Herman1  

E-print Network

Quantifying Nitrate Flux during Storm Events J. S. Herman1 , A. L. Mills1 , G. M. Hornberger1 , A St, Philadelphia, PA 19104; e-mail: mira.s.olson@drexel.edu. Abstract Excess nitrate, mainly due to coastal waters, but there are many unanswered questions pertaining to nitrate flux during storm events

Virginia, University of

350

9 CFR 319.2 - Products and nitrates and nitrites.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 false Products and nitrates and nitrites. 319.2 Section 319... General § 319.2 Products and nitrates and nitrites. Any product, such...is a standard in this part and to which nitrate or nitrite is permitted or required...

2014-01-01

351

Nitrate utilization and nitrogen status in English woodland communities  

E-print Network

Nitrate utilization and nitrogen status in English woodland communities E.C.M. Clough J. Pearson G- cies. The present study shows that leaf nitrate reduction is of common occurrence in woody plants of English woodland com- munities. Pioneer species tend to exhibit a greater capacity for leaf nitrate

Paris-Sud XI, Université de

352

LABORATORY EXPERIMENT 6 PRECIPITATION TITRATION WITH SILVER NITRATE.  

E-print Network

LABORATORY EXPERIMENT 6 PRECIPITATION TITRATION WITH SILVER NITRATE. The AgNO3 solution (~0.02 M in the titration of chloride ion with silver nitrate. The first excess of titrant results in the formation of a red Ag2CrO4. Calculations: From the volume of silver nitrate solution used fopr titration, calculate

Nazarenko, Alexander

353

Factors controlling nitrate fluxes in groundwater in agricultural areas  

E-print Network

Factors controlling nitrate fluxes in groundwater in agricultural areas Lixia Liao,1 Christopher T affecting distribution of agricultural nitrate in groundwater, a parsimonious transport model was applied, L., C. T. Green, B. A. Bekins, and J. K. Bo¨hlke (2012), Factors controlling nitrate fluxes

354

EUROPEAN LARGE LAKES III Identification of factors constraining nitrate assimilation  

E-print Network

EUROPEAN LARGE LAKES III Identification of factors constraining nitrate assimilation in Lake Science+Business Media Dordrecht 2013 Abstract Despite a well-documented rise in nitrate concentration to assess the influence of light and nutrients (P, Fe) on nitrate assimilation by a Lake Superior

Berges, John A.

355

9 CFR 319.2 - Products and nitrates and nitrites.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Products and nitrates and nitrites. 319.2 Section 319... General § 319.2 Products and nitrates and nitrites. Any product, such...is a standard in this part and to which nitrate or nitrite is permitted or required...

2013-01-01

356

21 CFR 176.320 - Sodium nitrate-urea complex.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2009-04-01 true Sodium nitrate-urea complex. 176.320 Section 176.320 Food...and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component...

2010-04-01

357

Expanded organic nitrate chemistry Abbreviation Name Abbreviation Name  

E-print Network

1 Appendix D Expanded organic nitrate chemistry Abbreviation Name Abbreviation Name ACD radical from ISOP Table D1 Chemical species in expanded organic nitrate chemistry. #12;2 Abbreviation Name MVK Table D1 (continued) Chemical species in expanded organic nitrate chemistry. #12;3 Species H* (M

Cohen, Ronald C.

358

21 CFR 176.320 - Sodium nitrate-urea complex.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Sodium nitrate-urea complex. 176.320 Section 176.320 Food...and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component...

2011-04-01

359

SULFATE AND NITRATE COATINGS ON MINERAL DUSTS: CRYSTALLINE OR AQUEOUS?  

E-print Network

02138, USA Keywords: Phase transition; Atmospheric Aerosols; Ammonium sulfate; Ammonium nitrate that of ammonium nitrate is 60%. The water content has several important effects. The particle volume increases relative humidity; D = diameter (nm) of mineral core particle; AS = ammonium sulfate; AN = ammonium nitrate

360

Thermal Dissociation Kinetics of Solid and Liquid Ammonium Nitrate  

E-print Network

Thermal Dissociation Kinetics of Solid and Liquid Ammonium Nitrate Sergey Vyazovkin,* Jacalyn S and liquid ammonium nitrate. Model-fitting and model-free kinetic methods have been applied to the sets/vaporization. Introduction Ammonium nitrate (AN) finds a widespread applica- tion as both fertilizer and energetic material

Utah, University of

361

Original article Ionic adsorption of ammonium and nitrate on some  

E-print Network

Original article Ionic adsorption of ammonium and nitrate on some animal litters and their role -- Two experiments were carried out to determine the adsorption of ammonium and nitrate on litters (Exp added to the tubes which were incubated for 24 h. Ammonium and nitrate concentrations, and pH, were

Paris-Sud XI, Université de

362

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...

363

NITRATE POLLUTION RISK ASSESSMENT: FROM THE MODEL TO THE INDICATOR  

E-print Network

study. INTRODUCTION Nitrate pollution is a threat to many of Europe's water resources, particularlyNITRATE POLLUTION RISK ASSESSMENT: FROM THE MODEL TO THE INDICATOR A. LACROIX 1 , F. LAURENT 2 , D. RUELLAND 3 , E. SAUBOUA 4 ABSTRACT The diffuse nature of nitrate pollution makes it difficult to evaluate

Paris-Sud XI, Université de

364

Selective Nitrate Binding in Competitive Hydrogen Bonding Solvents: Do Anion–? Interactions Facilitate Nitrate Selectivity?**  

PubMed Central

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–?” interaction between the nitrate and the ?-system of the ethynyl-substituted arene is proposed as the source of this selectivity. PMID:23939999

Watt, Michelle M.; Zakharov, Lev N.

2013-01-01

365

Wear resistant zirconium base alloy article for water reactors  

SciTech Connect

In a water reactor operating environment, the combination having improved fretting wear resistance is described comprising: an elongated tubular water displacer rod; having a low neutron absorption cross section guide support plates distributed along the length of the water displacer rod; the water displacer rod intersecting the guide support plates through apertures in the guide support plates; the water displacer rod having a plurality of spaced apart annular electrospark deposited coatings, each coating facing the wall of a respective aperture, the electrospark deposited coatings comprising Cr/sub 2/C/sub 3/; wherein the water displacer rod has a tube wall composed of a zirconium base alloy; and wherein the guide support plates are composed of a stainless steel alloy.

Gillett, J.E.; Shockling, L.A.; Sherwood, D.G.

1988-03-01

366

Fabrication of NiO/zirconium oxide nanofibers by electrospinning.  

PubMed

The electrospinning technique has been used to fabricate 1D inorganic-organic composite nanofibers from solutions containing poly(vinyl alcohol) (PVA) and suitable aqueous precursors of nickel and zirconium ions. Upon calcination, nickel oxide/zirconia nanofibers retained the original morphological features of as-spun nanofibers. X-ray diffraction was used to identify the crystalline nature of the final product and analytical tools such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) were employed to elucidate the pathway of ceramic phase formation and the systematic evolution of morphological features in the as-spun and calcined fibers. These fibers will find potential applications in biomedical field. PMID:25491841

Sundarrajan, Subramanian; Venkatesan, Arunachalam; Agarwal, Satya R; Shaik Anwar Ahamed, Nabeela Nasreen; Ramakrishna, Seeram

2014-12-01

367

Morphology of zirconia synthesized hydrothermally from zirconium oxychloride  

SciTech Connect

This paper reports that monoclinic zirconia has been synthesized hydrothermally from zirconium oxychloride in the range 20--100 MPa, 250--650[degrees]C, for run duration from 20 to 100 h and in the presence of NaOH, Na[sub 2]CO[sub 3], Na[sub 2]SO[sub 4], NH[sub 4]F, HNO[sub 3], and H[sub 2]SO[sub 4] additives. Isometric, platelike, and elongated crystal morphologies were obtained depending on the additive. Both spherulitic and isolated textures were encountered with H[sub 2]SO[sub 4]. Growth of isometric crystals follows a general dissolution--precipitation mechanism. For H[sub 2]SO[sub 4], two growth steps were identified: an early spherulitic step followed by an isolated crystals step resulting from Ostwald ripening of preexisting spherulites. The formation of spherulites is consistent with the specific properties of the sulfuric hydrothermal medium.

Mottet, B.; Pichavant, M.; Beny, J.M. (Centre de Recherche sur la Synthese et la Chimie des Mineraux, 45 071 Orleanss Cedex 02 (France)); Alaary, J.A. (Secteur Elaboration des Materiaux, Centre de Recherches de Voreppe, 38 340 Voreppe (France))

1992-09-01

368

Long-term leaching behaviour of glasses containing zirconium  

NASA Astrophysics Data System (ADS)

Five borosilicate glasses containing up to 20% zirconium oxide and 10% non-radioactive fission products or lanthanum oxide (which simulates the behaviour of the actinides) were leached in stagnant distilled water at 20 ° C for 2 years. The leaching rates of Na, La, Mn, Cs and Mo varied with time and the chemical composition of the glass from 0.7 to 12, 0.006 to 0.14, 0.8 to 1.2, 0.4 to 0.8 and 8 to 25 mg/m 2/d respectively. The glasses which showed the beast short-term resistance do not have the best long-term resistance.

St.-Pierre, Jean; Zikovsky, L.

1984-08-01

369

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

NASA Technical Reports Server (NTRS)

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.

2003-01-01

370

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

NASA Technical Reports Server (NTRS)

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.

2003-01-01

371

Hydrogen absorption by zirconium alloys at high temperatures  

NASA Astrophysics Data System (ADS)

At high temperatures, e.g. during a hypothetical severe accident, zirconium and its alloys are not stable to other materials and to oxidising atmospheres. Exothermic reactions with steam cause the production of hydrogen which will be released to the atmosphere and, thus, endanger the containment or may be absorbed by the remaining metal. The hydrogen solubility in Zircaloy-4 and Zr-1Nb was measured in the temperature range of 1230-1730 K and at hydrogen partial pressures between 10 and 100 kPa. The parameters of the Sieverts constant were determined. No significant differences between the two alloys were observed. The hydrogen solubility of oxygen containing Zircaloy-4 decreases with increasing oxygen content.

Steinbrück, Martin

2004-08-01

372

Effect of yttrium on nucleation and growth of zirconium hydrides  

NASA Astrophysics Data System (ADS)

Addition of yttrium in zirconium causes precipitates of yttrium, which form two types of particles and are oxidized upon heat treatment. One type of particles with sub-micrometer scale sizes has a low population, whereas the other with nano scale sizes has a high population and cluster distribution. Owing to strong affinity of yttrium to hydrogen, the nanoparticles, mostly within the grains of the Zr-Y alloy, attract nucleation of hydrides at the clusters of the nanoparticles and cause preferential distribution of intragranular hydrides. In comparison with that of Zr, additional nanoparticles in the Zr-Y alloy impede further growth of hydride precipitates during hydriding. It is deduced that the impediment of growing hydride precipitates by the nanoparticles is developed during an auto-catalytic nucleation process, which leads to formation of thin and intragranular hydrides, favorable to mitigation of hydride embrittlement.

Li, Changji; Xiong, Liangyin; Wu, Erdong; Liu, Shi

2015-02-01

373

Arginase II inhibition prevents nitrate tolerance  

PubMed Central

BACKGROUND AND PURPOSE Nitrate tolerance, the loss of vascular responsiveness with continued use of nitrates, remains incompletely understood and is a limitation of these therapeutic agents. Vascular superoxide, generated by uncoupled endothelial NOS (eNOS), may play a role. As arginase competes with eNOS for L-arginine and may exacerbate the production of reactive oxygen species (ROS), we hypothesized that arginase inhibition might reduce nitrate tolerance. EXPERIMENTAL APPROACH Vasodilator responses were measured in aorta from C57Bl/6 and arginase II knockout (argII –/–) mice using myography. Uncoupling of eNOS, determined as eNOS monomer : dimer ratio, was assessed using low-temperature SDS-PAGE and ROS levels were measured using L-012 and lucigenin-enhanced chemiluminescence. KEY RESULTS Repeated application of glyceryl trinitrate (GTN) on aorta isolated from C57Bl/6 mice produced a 32-fold rightward shift of the concentration–response curve. However this rightward shift (or resultant tolerance) was not observed in the presence of the arginase inhibitor (s)-(2-boronethyl)-L-cysteine HCl (BEC; 100 µM) nor in aorta isolated from argII –/– mice. Similar findings were obtained after inducing nitrate tolerance in vivo. Repeated administration of GTN in human umbilical vein endothelial cells induced uncoupling of eNOS from its dimeric state and increased ROS levels, which were reduced with arginase inhibition and exogenous L-arginine. Aortae from GTN tolerant C57Bl/6 mice exhibited increased arginase activity and ROS production, whereas vessels from argII –/– mice did not. CONCLUSION AND IMPLICATIONS Arginase II removal prevents nitrate tolerance. This may be due to decreased uncoupling of eNOS and consequent ROS production. PMID:22288373

Khong, SML; Andrews, KL; Huynh, NN; Venardos, K; Aprico, A; Michell, DL; Zarei, M; Moe, KT; Dusting, GJ; Kaye, DM; Chin-Dusting, JPF

2012-01-01

374

Anisole Nitration During Gamma-Irradiation of Aqueous Nitrite and Nitrate Solutions: Free Radical Versus Ionic Mechanisms  

SciTech Connect

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.

Gracy Elias; Bruce J. Mincher; Leigh R. Martin; Stephen P. Mezyk; Thomas D. Cullen

2010-04-01

375

Simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys.  

PubMed

A simple analytical procedure is described for determining zirconium or hafnium in molybdenum-base alloys by formation of the Arsenazo III complex of zirconium or hafnium in 9 M hydrochloric acid medium. The absorbance is measured at 670 nm. Molybdenum (10 mg), titanium (1 mg), and rhenium (10 mg) have no adverse effect. No prior separation is needed. The relative standard deviation is 1.3-2.7%. PMID:18961121

Dupraw, W A

1972-06-01

376

Acid-base properties of sorbents based on modified zirconium(IV) phosphates  

SciTech Connect

Modifying and doping syntheses are widely used to improve the reproducibility of ion-exchange properties and to increase the capacity of inorganic ion exchangers. Numerous examples of doping zirconium phosphate ion exchangers with cationic or anionic additives are known. The aim of this work was to investigate the acid-base properties of zirconium phosphates modified with anionic additives (phthalate and sulfosalicylate ions) in comparison with unmodified samples.

Bekrenev, A.V. [Research Center of Environmental Safety, St. Petersburg (Russian Federation); Pyartman, A.K. [St. Petersburg Institute of Technology (Russian Federation)

1995-11-01

377

Efficient UV-Emitting X-Ray Phosphors: Potassium Hafnium-Zirconium Phosphates  

E-print Network

Efficient UV-Emitting X-Ray Phosphors: Potassium Hafnium-Zirconium Phosphates K2Hf1-xZrx(PO4 Abstract Potassium hafnium-zirconium phosphates, K2Hf1-xZrx(PO4)2 and KHf2(1-x)Zr2x(PO4)3 are broad-band UV.e., those with emission less than 400 nm). Attention was given to hafnium-oxide based phosphors because HfO2

Li, Jing

378

Atomic Diffusion in the Uranium-50wt% Zirconium Nuclear Fuel System  

E-print Network

ATOMIC DIFFUSION IN THE URANIUM-50WT% ZIRCONIUM NUCLEAR FUEL SYSTEM A Thesis by DANIEL R. EICHEL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... design concept. Image courtesy Lightbridge Corporation. ............................................... 2 Figure 2: Phase diagram for the binary zirconium-uranium system, showing the existence of the ? phase below 600?C for alloy compositions...

Eichel, Daniel

2013-06-17

379

Status of highly loaded uranium-zirconium hydride Low Enriched Uranium (LEU) fuel programs  

Microsoft Academic Search

The LEU uranium-zirconium hydride fuel has successfully completed all essential development testing and is offered commercially in both the 20 weight percent and 45 weight percent uranium concentrations for existing TRIGA reactors and as a conversion fuel for plate-type reactors. Several reactor facilities have already begun conversion to LEU uranium-zirconium hydride fuel. Currently, U-ZrH LEU fuel is in use in

1984-01-01

380

Graded selective coatings based on zirconium and titanium oxynitride  

NASA Astrophysics Data System (ADS)

The aim of this study was the development and characterization of transition metal oxynitride multilayers for optical applications. The reactive RF magnetron sputtering technique in rotation mode was used for stacking of zirconium oxynitride (ZrNO) and titanium oxynitride (TiNO) nanolayers. The depositions were carried out in a reactive Ar+N2+O2 atmosphere by sputtering titanium and zirconium targets. By means of different substrate rotation speeds, the bilayer period has been changed in the range 11-20 nm. A multilayer deposition rate increasing with the bilayer period decreasing has been evaluated. Structural, compositional, mechanical and optical analyses have been performed. The x-ray diffraction spectra confirmed the formation of a multilayer structure with a nitride formation prevalence. Non-abrupt interfaces between the layers and non-uniform chemical composition (chemical intermixing) have been detected by transmission electron microscope (TEM) observations. The gradient interface structure turns out to be an advantage for the improvement of the mechanical properties. Higher hardness values were calculated by the Chicot-Lesage and Jonsson-Hogmark models for TiNO/ZrNO multilayer compared with monolayer TiNO and ZrNO coatings. Also SIMS analysis has confirmed a compositional interface grading but also an increase in oxygen content with decreasing substrate rotation speed or similarly with decreasing deposition rate. Moreover, a tuning of the optical properties, going from metallic behaviour to dielectric with the decrease in the substrate rotation speed has been gained. The variation of the deposition rate allows a sort of 'regulation' of the oxygen incorporation with a precise tailoring of the optical properties. This result can be employed with the aim of depositing graded composition multilayer systems with a precise control of their optical selective wavelength properties. The improvement in the mechanical performance in graded oxynitride multilayer coatings would also allow an increase in the optical device lifetime.

Rizzo, A.; Signore, M. A.; Tapfer, L.; Piscopiello, E.; Cappello, A.; Bemporad, E.; Sebastiani, M.

2009-06-01

381

Ion beam mixing of chromium or zirconium films with sapphire  

SciTech Connect

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.

McHargue, C.J. [Tennessee Univ., Knoxville, TN (United States); Joslin, D.L.; White, C.W. [Oak Ridge National Lab., TN (United States); daSilva, M.F.; Alves, E. [National Inst. for Industrial Technology and Engineering, Sacavem (Portugal); Soares, J.C. [Lisbon Univ. (Portugal)

1995-12-31

382

The nitrate time bomb: a numerical way to investigate nitrate storage and lag time in the unsaturated zone.  

PubMed

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

Wang, L; Butcher, A S; Stuart, M E; Gooddy, D C; Bloomfield, J P

2013-10-01

383

Extraction of nitric acid, uranyl nitrate, and bismuth nitrate from aqueous nitric acid solutions with CMPO  

SciTech Connect

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.

Spencer, B.B.

1995-08-01

384

Mechanical resistance of zirconium implant abutments: A review of the literature  

PubMed Central

The increase of aesthetic demands, together with the successful outcome of current implants, has renewed interest in the search for new materials with enough mechanical properties and better aesthetic qualities than the materials customarily used in implanto-prosthetic rehabilitation. Among these materials, zirconium has been used in different types of implants, including prosthetic abutments. The aim of the present review is to analyse current scientific evidence supporting the use of this material for the above mentioned purposes. We carried out the review of the literature published in the last ten years (2000 through 2010) of in vitro trials of dynamic and static loading of zirconium abutments found in the databases of Medline and Cochrane using the key words zirconium abutment, fracture resistance, fracture strength, cyclic loading. Although we have found a wide variability of values among the different studies, abutments show favourable clinical behaviour for the rehabilitation of single implants in the anterior area. Such variability may be explained by the difficulty to simulate daily mastication under in vitro conditions. The clinical evidence, as found in our study, does not recommend the use of implanto-prosthetic zirconium abutments in the molar area. Key words: Zirconium abutment, zirconium implant abutment, zirconia abutment, fracture resistance, fracture strength, cyclic loading. PMID:22143702

Vaquero-Aguilar, Cristina; Torres-Lagares, Daniel; Jiménez-Melendo, Manuel; Gutiérrez-Pérez, José L.

2012-01-01

385

Induction and Repression of Nitrate Reductase in Neurospora crassa  

PubMed Central

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at least one of three other activities associated with the wild-type enzyme. The two mutants do not require the presence of nitrate for induction of their aberrant nitrate reductases and are constitutive for their component nitrate reductase activities in the absence of ammonium ions. (ii) An analog of the wild-type enzyme (similar to the nit-1 enzyme) is formed when wild type is grown in a medium in which molybdenum has been replaced by vanadium or tungsten; the resulting enzyme lacks NADPH-nitrate reductase activity. Unlike nit-1, wild type produced this analog only in the presence of nitrate. Contaminating nitrate does not appear to be responsible for the observed mutants' activities. Nitrate reductase is proposed to be autoregulated. (iii) Mutants (am) lacking NADPH-dependent glutamate dehydrogenase activity partially escape ammonium repression of nitrate reductase. The presence of nitrate is required for the enzyme's induction. (iv) A double mutant, nit-1 am-2, proved to be an ideal test system to study the repressive effects of nitrogen-containing metabolites on the induction of nitrate reductase activity. The double mutant does not require nitrate for induction of nitrate reductase, and synthesis of the enzyme is not repressed by the presence of high concentrations of ammonium ions. It is, however, repressed by the presence of any one of six amino acids. Nitrogen metabolites (other than ammonium) appear to be responsible for the mediation of “ammonium repression.” PMID:146700

Dantzig, Anne H.; Zurowski, Wayne K.; Ball, Thomas M.; Nason, Alvin

1978-01-01

386

Nitrate reduction and nitrate content in ash trees ( Fraxinus excelsior L.): distribution between compartments, site comparison and seasonal variation  

Microsoft Academic Search

Nitrate reductase activity (NRA), nitrate content and biomass components of leaflets, leaf stalks, old stem, current-year stem and roots of ash trees (Fraxinus excelsior L.) growing in their natural habitats were investigated. In addition, NRA, total nitrogen and nitrate concentration were analyzed in the leaves and roots of ash trees from four different field sites. The highest NRA per gram

J. Stadler; G. Gebauer

1992-01-01

387

Comparison of optical properties of nitrate and sulfate aerosol and the direct radiative forcing due to nitrate in China  

E-print Network

Comparison of optical properties of nitrate and sulfate aerosol and the direct radiative forcing due to nitrate in China H. Zhang a, , Z. Shen a,b , X. Wei a,c , M. Zhang d , Z. Li e,f a Laboratory the direct radiative forcing (DRF) due to nitrate aerosols. Ensuing errors have not been rigorously evaluated

Li, Zhanqing

388

(Di­methyl­phosphor­yl)methanaminium nitrate  

PubMed Central

In the crystal of the title salt, C3H11NOP+·NO3 ?, dicationic inversion dimers are head-to-tail connected by a pair of strong N—H?O hydrogen bonds. The resulting graph-set descriptor of this ring system is R 2 2(10). The nitrate counter-anions connect the dicationic dimers via N—H?O hydrogen bonds, forming two-dimensional networks in the bc plane. PMID:24454084

Bianga, Claudia M.; Eggeling, Julia; Reiss, Guido J.

2013-01-01

389

Nitrate and phosphate removal by Spirulina platensis  

Microsoft Academic Search

The cyanobacterium Spirulina platensis was used to verify the possibility of employing microalgal biomass to reduce the contents of nitrate and phosphate in wastewaters. Batch tests were carried out in 0.5 dm 3 Erlenmeyer flasks under conditions of light limitation (40 µmol quanta m -2 s -1) at a starting biomass level of 0.50 g\\/dm 3 and varying temperature in the range 23–40°C. In this

A. Lodi; L. Binaghi; C. Solisio; A. Converti; M. Del Borghi

2003-01-01

390

Actinide partitioning from actual ICPP dissolved zirconium calcine using the TRUEX solvent  

SciTech Connect

The TRansUranic EXtraction process (TRUEX), as developed by E.P. Horwitz and coworkers at Argonne National Laboratory (ANL), is being evaluated as a TRU extraction process for Idaho Chemical Processing Plant (ICPP) wastes. A criteria that must be met during this evaluation, is that the aqueous raffinate must be below the 10 nCi/g limit specified in 10 CFR 61.55. A test was performed where the TRUEX solvent (0.2 M octyl(phenyl)-N-N-diisobutyl-carbamoylmethyl-phosphine oxide (CMPO), and 1.4 M tributylphosphate (TBP) in an Isopar-L diluent) was contacted with actual ICPP dissolved zirconium calcine. Two experimental flowsheets were used to determine TRU decontamination factors, and TRU, Zr, Fe, Cr, and Tc extraction, scrub, and strip distribution coefficients. Results from these two flowsheets show that >99.99% of the TRU alpha activity was removed from the acidic feed after three contacts with the TRUEX solvent (fresh solvent being used for each contact). The resulting aqueous raffinate solution contained an approximate TRU alpha activity of 0.02 nCi/g, which is well below the non-TRU waste limit of 10 nCi/g specified in 10 CFR 61.55. Favorable scrub and strip distribution coefficients were also observed for Am-241, Pu-238, and Pu-239, indicating the feasibility of recovering these isotopes from the TRUTEX solvent. A solution of 0.04 M 1-hydroxyethane-1,1-diphosphonic acid (HEDPA) in 0.04 M HNO{sub 3} was used to successfully strip the TRUs from the TRUEX solvent. The results of the test using actual ICPP dissolved zirconium calcine, and subsequent GTM evaluation, show the feasibility of removing TRUs from the dissolved zirconium calcine with the TRUEX solvent and the deleterious effects zirconium poses with the ICPP zirconium calcine waste. Test results using actual ICPP zirconium calcine reveal the necessity of preventing zirconium from following the TRUs.

Brewer, K.N.; Herbst, R.S.; Tranter, T.J. [and others

1995-05-01

391

Carbonyl Alkyl Nitrates as Trace Constituents in Urban Air  

NASA Astrophysics Data System (ADS)

Organic nitrates, esters of nitric acid, significantly contribute to the entire pool of odd nitrogen (NOY) in the atmosphere. Organic nitrates are formed in NO rich air by degradation of alkanes and alkenes initiated by OH and NO3 radicals during daytime and nighttime, respectively. Bifunctional organonitrates like the alkyl dinitrates and hydroxy alkyl nitrates are formed primarily from alkenes. The two main sources for Alkenes are traffic emissions and naturally occurring terpenes. So far a broad spectrum of alkyl dinitrates and hydroxy alkyl nitrates including six different isoprene nitrates has been identified in urban and marine air (1-3). We report here for the first time about the group of C4 C7 carbonyl alkyl nitrates as trace constituents in urban air collected on the campus of the University of Ulm Germany, and in the downtown area of Salt Lake City, Utah. Air sampling was done by high volume sampling (flow rate 25 m3/h) using a layer of 100 g silica gel (particle diameter 0.2 - 0.5 mm) as adsorbent. The organic nitrates were eluted from the silica gel by pentane/acetone (4:1, w/w) and the extract was concentrated to a volume of 500 µL for a group separation using normal phase HPLC. Final analysis was performed by high resolution capillary gas chromatography with electron capture detection as well as by mass selective detection in the (CH4)NCI mode using NO2- = m/e 46 as the indicator mass. The carbonyl alkyl nitrates were identified by self synthesized reference standards . So far we have identified eight non-branched a-carbonyl alkyl nitrates (vicinal carbonyl alkyl nitrates), two b-carbonyl alkyl nitrates and one g-carbonyl alkyl nitrate with carbon chains ranging from C4 to C7. The mixing ratios are between 0.05 and 0.30 ppt(v) for daytime samples and are two to three times higher for samples taken at night. (1) M. Schneider, O. Luxenhofer, Angela Deißler, K. Ballschmiter: 2C1-C15 Alkyl Nitrates, Benzyl Nitrate, and Bifunctional Nitrates: Measurements in Californian and South Atlantic Air and Global Comparison Using C2Cl4 and CHBr3 as Marker Molecules2 Environ. Sci. Technol. (1998) 32: 3055-3062. (2) G. Werner, J. Kastler, R. Looser, K. Ballschmiter: 2Organic nitrates of isoprene as atmospheric trace compounds2 Angewandte Chemie International Edition (1999) 38: 1634- 1637. (3) RG Fischer; J. Kastler, K. Ballschmiter, "Levels and pattern of alkyl nitrates, multifunctional alkyl nitrates, and halocarbons in the air over the Atlantic Ocean" J. Geophys. Res. - Atmosphere (2000) 105: 14 473-14 494.

Woidich, S.; Gruenert, A.; Ballschmiter, K.

2003-04-01

392

Synthesis and liquid crystal phase transitions of zirconium phosphate disks  

NASA Astrophysics Data System (ADS)

Solvent-mediated self-assembly of nanoparticles is an effective and efficient way for the bottom-up organization of functional structures. The primary object of this work is to build up a model system for the study of suspensions of disk-shaped nanoparticles, and use it for the study of self-assembly and discotic liquid crystal phase transitions of discotic particles. The work was introduced by the control over the size and polydispersity of zirconium phosphate (ZrP) disks through synthesis. Systematic experiments revealed that regular-shaped alpha-zirconium phosphate crystalline disks with a size-to-thickness ratio from 1 to 50 and size polydispersity as low as 0.2 can be obtained through hydrothermal treatment in 3 M to 15 M phosphoric acid solutions. Transmission and scanning electron micrographs revealed that the growth of the disks is mediated by oriented attachment, which happened continuously throughout the hydrothermal treatment between various sized disks. Ostwald ripening is effective in improving the regularity of the shape of the disks, especially under prolonged hydrothermal treatment. Under the microwave assisted hydrothermal conditions, the rate of attachment on the flat surfaces of the disks is accelerated, which leads to the formation of the column-shaped crystals. With the ability to adjust the size, aspect ratio, and polydispersity of ZrP disks, the study on self-assembly behavior and the discotic liquid crystal phases was enabled. Firstly, liquid crystal phases of aqueous suspensions of ZrP disks were investigated. Iridescent smectic phase and the critical points of phase transitions were found. Moreover, monolayer ZrP nanosheets with extremely high aspect ratio, which were achieved by exfoliating the ZrP crystals, were also used in this study. The high aspect ratio of nanosheets produces a laminar phase at low nanosheet concentration. Chiral liquid crystal phases were demonstrated when increased the concentration of the nanosheets. The competition between the chirality and layering leads to twisted and layered structures. For the final part, solvent-mediated self-assembly of disks and nanosheets via undulation of liquid crystal phases showed an interesting approach for bottom-up design of functional nano-structures.

Shuai, Min

393

Highly enantioselective zirconium-catalyzed cyclization of aminoalkenes.  

PubMed

Aminoalkenes are catalytically cyclized in the presence of cyclopentadienylbis(oxazolinyl)borato group 4 complexes {PhB(C5H4)(Ox(R))2}M(NMe2)2 (M = Ti, Zr, Hf; Ox(R) = 4,4-dimethyl-2-oxazoline, 4S-isopropyl-5,5-dimethyl-2-oxazoline, 4S-tert-butyl-2-oxazoline) at room temperature and below, affording five-, six-, and seven-membered N-heterocyclic amines with enantiomeric excesses of >90% in many cases and up to 99%. Mechanistic investigations of this highly selective system employed synthetic tests, kinetics, and stereochemistry. Secondary aminopentene cyclizations require a primary amine (1-2 equiv vs catalyst). Aminoalkenes are unchanged in the presence of a zirconium monoamido complex {PhB(C5H4)(Ox(4S-iPr,Me2))2}Zr(NMe2)Cl or a cyclopentadienylmono(oxazolinyl)borato zirconium diamide {Ph2B(C5H4)(Ox(4S-iPr,Me2))}Zr(NMe2)2. Plots of initial rate versus [substrate] show a rate dependence that evolves from first-order at low concentration to zero-order at high concentration, and this is consistent with a reversible substrate-catalyst interaction preceding an irreversible step. Primary kinetic isotope effects from substrate conversion measurements (k'obs((H))/k'obs((D)) = 3.3 ± 0.3) and from initial rate analysis (k2((H))/k2((D)) = 2.3 ± 0.4) indicate that a N-H bond is broken in the turnover-limiting and irreversible step of the catalytic cycle. Asymmetric hydroamination/cyclization of N-deutero-aminoalkenes provides products with higher optical purities than obtained with N-proteo-aminoalkenes. Transition state theory, applied to the rate constant k2 that characterizes the irreversible step, provides activation parameters consistent with a highly organized transition state (?S(++) = -43(7) cal·mol(-1) K(-1)) and a remarkably low enthalpic barrier (?H(++) = 6.7(2) kcal·mol(-1)). A six-centered, concerted transition state for C-N and C-H bond formation and N-H bond cleavage involving two amidoalkene ligands is proposed as most consistent with the current data. PMID:23631736

Manna, Kuntal; Everett, William C; Schoendorff, George; Ellern, Arkady; Windus, Theresa L; Sadow, Aaron D

2013-05-15

394

Growing patterns to produce 'nitrate-free' lettuce (Lactuca sativa).  

PubMed

Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p < 0.05) in the fresh mass was recorded. The concentrations of nitrite in the lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way. PMID:25345876

Croitoru, Mircea Dumitru; Muntean, Daniela-Lucia; Fülöp, Ibolya; Modroiu, Adriana

2015-01-01

395

Reductive denitrification of nitrate by scrap iron filings.  

PubMed

Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial concentration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed. PMID:15682502

Hao, Zhi-Wei; Xu, Xin-Hua; Wang, Da-Hui

2005-03-01

396

Reductive denitrification of nitrate by scrap iron filings*  

PubMed Central

Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial concentration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed. PMID:15682502

Hao, Zhi-wei; Xu, Xin-hua; Wang, Da-hui

2005-01-01

397

UTILIZATION OF NITRATE BY PATHOGENIC AND SAPROPHYTIC MYCOBACTERIA  

PubMed Central

Hedgecock, L. W. (Veterans Administration Hospital, Kansas City, Mo.) and R. L. Costello. Utilization of nitrate by pathogenic and saprophytic mycobacteria. J. Bacteriol. 84:195–205. 1962—The ability of mycobacteria to utilize nitrate as a sole source of nitrogen was examined. Nitrate-nitrogen was readily utilized by Mycobacterium butyricum, M. smegmatis, and M. tuberculosis H37Ra. Nitrate and nitrite were both utilized as sole sources of nitrogen by M. tuberculosis H37Rv. The saprophytes and drug-resistant strains of tubercle bacilli failed to reduce nitrate after having been cultured repeatedly and stored in Kirchner medium. It was necessary to add molybdenum to Kirchner medium for continued nitrate reduction by the saprophytic mycobacteria, but not for M. tuberculosis. Nitrate reductase of M. tuberculosis was inhibited by tungstate; the inhibition was reversed by molybdate at a concentration of 1:10,000. Optimal conditions for the reduction of nitrate by washed whole cells and by a particulate sonictreated extract of M. tuberculosis were studied. Reduced diphosphopyridine nucleotide was required for reduction of nitrate by the cell extract. Nitrate reduction was inhibited by isoniazid but not by p-aminosalicylic acid or streptomycin. PMID:13905880

Hedgecock, L. W.; Costello, R. L.

1962-01-01

398

Bismuth nitrate-induced novel nitration of estradiol: an entry to new anticancer agents.  

PubMed

Direct nitration of estradiol was carried out using metal nitrates on solid surfaces under mild condition, and a combination of bismuth nitrate pentahydrate impregnated KSF clay was found to be the best reagent to synthesize 2- and 4-nitroestradiol effectively. Furthermore, various basic side chains were introduced, through O-linker at C-3, to these nitroestradiols. The ability of these derivatives to cause cytotoxicity in Estrogen Receptor (ER)-positive and ER-negative breast cancer cell lines, as well as cancer cell lines of other origins, was examined. Qualitative structure activity relationship (SAR) has also been studied. We found that a basic side chain containing either a piperidine or morpholine ring, when conjugated to 2-nitroestradiol, was particularly effective at causing cytotoxicity in each of the cancer cell lines examined. Surprisingly, this effective cytotoxicity was even seen in ER-negative breast cancer cells. PMID:24946145

Bandyopadhyay, Debasish; Rivera, Gildardo; Sanchez, Jorge L; Rivera, Jesse; Granados, Jose C; Guerrero, Adrian M; Chang, Fang-Mei; Dearth, Robert K; Short, John D; Banik, Bimal K

2014-07-23

399

Electrospun poly (vinyl alcohol)/ alpha-zirconium phosphate nanocomposite fibers  

NASA Astrophysics Data System (ADS)

Poly (vinyl alcohol) (PVA)/alpha-zirconium phosphate (ZrP) polymer nanocomposite (PNC) fibers were successfully prepared via the simple and low-cost electrospinning process. ZrP nanoparticles with two different dimensions, i.e., ZrP-500 with a lateral dimension of ca. 320 nm and an aspect ratio of ca. 500, and ZrP-1500 with a lateral dimension of ca. 950 nm and an aspect ratio of ca. 1500, were utilized to illustrate the size effect on the electrospun nanofibers. In order to obtain defect-free, uniform polymer nanocomposite fibers, a number of parameters including polymer concentration, feed rate, applied voltage and working distance between the needle tip and the fiber collecting substrate were investigated. Scanning electron microscopy (SEM) morphological analysis showed smooth and nonwoven electrospun nanofiber mat. Strong intermolecular interactions between the PVA matrix and the included ZrP nanofillers were revealed by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The incorporation of ZrP nanofillers drastically improved the thermal stability of the PNC fibers. TGA results demonstrated a clear thermal stability dependence on the aspect ratio of the crystalline ZrP nanofillers. The degradation temperature was increased by 90 °C for the ZrP-1500 and 60 °C for ZrP-500 when the loading level was increased from 1% to 5%. Furthermore, the viscoelastic properties of the PNC solutions were studied by rheometer.

Lizu, Monira

400

Synthesis and Characterization of Zirconium Tungstate Ultra-Thin Fibers  

SciTech Connect

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.

Zhang, Lifeng [South Dakota School of Mines and Technology; Howe, Jane Y [ORNL; Fong, Hao [South Dakota School of Mines and Technology; Zhang, Yan [Anhui Normal University, People's Republic of China

2009-01-01

401

Surface modification of Zircaloy-4 substrates with nickel zirconium intermetallics  

NASA Astrophysics Data System (ADS)

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.

Luscher, Walter G.; Gilbert, Edgar R.; Pitman, Stan G.; Love, Edward F.

2013-02-01

402

Zirconium and hafnium Salalen complexes in isospecific polymerisation of propylene.  

PubMed

The activity of dibenzylzirconium and dibenzylhafnium Salalen complexes in polymerisation of propylene with MAO as a cocatalyst is described. Three Salalen ligand precursors combining a bulky alkyl group (1-adamantyl) on the imine-side phenol and electron withdrawing halo groups of different sizes on the amine-side phenol were explored. All metal complexes were obtained as single diastereomers. An X-ray crystallographic structure of a hafnium complex of an additional ligand carrying the combination of tert-butyl and chloro substituted phenolates, 4-Hf, revealed a fac-mer wrapping of the Salalen ligand around the metal centre. All complexes led to active catalysts in propylene polymerisation and to isotactic polypropylene of high regioregularity. The zirconium complexes led to polypropylene having molecular weights of Mw = 132,000-200,000 and isotacticities of [mmmm] = 65.7-75.0%. The hafnium complexes led to polypropylene of higher molecular weights of Mw = 375,000-520,000 and higher stereoregularities of [mmmm] = 80.6-89.3%, the highest isotacticity obtained with 3-Hf. PMID:23471354

Press, Konstantin; Venditto, Vincenzo; Goldberg, Israel; Kol, Moshe

2013-07-01

403

Fracture Resistance of a Zirconium Alloy with Reoriented Hydrides  

NASA Astrophysics Data System (ADS)

Zirconium alloy cladding materials typically contain circumferential hydrides that may be reoriented to align along the radial direction when the cladding tubes are heated above and then cooled below the solvus temperature. The objectives of this study were to investigate the critical stress levels required to cause hydride reorientation (HRT) and to characterize the fracture resistance of Zircaloy-2 after hydride reorientation. HRT heat-treatment was performed on hydrogen-charged Zircaloy-2 specimens at 593 K (320 °C) or 623 K (350 °C) for 1 to 2 hours, followed by cooling to 473 K (200 °C). Fracture testing was conducted on hydride-reoriented three-point bend specimens at 473 K (200 °C) using an in situ loading stage inside a scanning electron microscope. Direct observations indicated that the reoriented hydrides, which ranged from ?1 to 22 ?m in lengths, were more prone to fracture at larger sizes (>10 ?m) compared to smaller sizes (<0.5 ?m). The reoriented hydrides reduced fracture resistance through a void nucleation, growth, and coalescence process at the crack tip. The resulting crack-resistance curves for Zircaloy-2 with reoriented hydrides decrease from 38 to 21 MPa(m)1/2 with increasing hydrogen contents from 51 to 1265 wt ppm hydrogen.

Chan, Kwai S.; He, Xihua; Pan, Yi-Ming

2015-01-01

404

The effect of zirconium implantation on the structure of sapphire  

SciTech Connect

The effect of zirconium implantation on the structure of sapphire was investigated by 175 keV Zr implantation at room temperature to a fluence of 4 1016 ions/cm2 into sapphire single crystals. Samples were examined by several experimental techniques: Rutherford backscattering spectroscopy along a channeling direction (RBS-C), electron-energy loss spectroscopy (EELS), and Z-contrast images obtained in an aberration-corrected scanning transmission electron microscope. Range and deposited energy were simulated with SRIM-2008.04. The Z-contrast images from transmission electron microscope indicated: a near surface damaged layer ~30 nm thick, a subsurface region exhibiting "random" de-channeling ~52 nm thick, and a deeper damaged, crystalline zone ~64 nm thick. The RBS-C spectra confirmed the presence of these three regions. The two damaged regions contained high concentrations of as yet unresolved defect clusters. The intermediate region contained Zr-clusters embedded in an "amorphous" matrix that exhibited short-range order corresponding to -Al2O3, i.e., a defective spinel structure. The EELS measurements show that the amorphous region is deficient in oxygen.

Sina, Younes [University of Tennessee, Knoxville (UTK); McHargue, Carl J [University of Tennessee, Knoxville (UTK); Duscher, Gerd [University of Tennessee, Knoxville (UTK); Zhang, Yanwen [ORNL

2012-01-01

405

Characterization of precipitates in a niobium-zirconium-carbon alloy  

NASA Technical Reports Server (NTRS)

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.

Grobstein, T. L.; Titran, R. H.

1986-01-01

406

Effects of Fast Neutron Irradiation on Zirconium Carbide  

SciTech Connect

High-purity zone refined zirconium carbide has been fast neutron irradiated in the dose and temperature range of 1-10 x 10{sup 25} N/m{sup 2} (E > 0.1 MeV) and 635-1480 C, respectively. Non-irradiated and as-irradiated properties were measured including the lattice parameter, hardness and elastic modulus as determined through nano-indentation, thermal conductivity, and indentation fracture toughness. The effects of neutron irradiation on the microstructure were also determined though using transmission electron microscopy. The general finding of this paper, limited to this particular zone refined ZrC of nominal C/Zr ratio of 0.93, is that this ceramic is quite stable under neutron irradiation in the temperature and dose range studied. Measurement of lattice parameter before and after irradiation indicated a lack of significant crystalline strain due to irradiation. Only modest changes were observed in the mechanical properties of hardness, elastic modulus, and indentation fracture toughness. The thermal conductivity underwent a slight reduction near 1000 C irradiation, though was essentially unchanged for 1300-1480 C irradiation. Transmission electron microscopy revealed black-spot-type defects (likely Frank or other small loops) for irradiation at 670 C, maturing to faulted Frank loops at 1280 C. As the irradiation temperature increased from 1280 C to the highest irradiation temperature, of 1496 C, a transition to prismatic loops occurs.

Snead, Lance Lewis [ORNL; Katoh, Yutai [ORNL; Kondo, Sosuke [ORNL

2010-01-01

407

Characterization of zirconium thin films deposited by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

Zirconium (Zr) thin films deposited on Si (100) by pulsed laser deposition (PLD) at different pulse repetition rates are investigated. The deposited Zr films exhibit a polycrystalline structure, and the X-ray diffraction (XRD) patterns of the films show the ? Zr phase. Due to the morphology variation of the target and the laser—plasma interaction, the deposition rate significantly decreases from 0.0431 Å/pulse at 2 Hz to 0.0189 Å/pulse at 20 Hz. The presence of droplets on the surface of the deposited film, which is one of the main disadvantages of the PLD, is observed at various pulse repetition rates. Statistical results show that the dimension and the density of the droplets increase with an increasing pulse repetition rate. We find that the source of droplets is the liquid layer formed under the target surface. The dense nanoparticles covered on the film surface are observed through atomic force microscopy (AFM). The root mean square (RMS) roughness caused by valleys and islands on the film surface initially increases and then decreases with the increasing pulse repetition rate. The results of our investigation will be useful to optimize the synthesis conditions of the Zr films.

Liu, Wei; Wan, Jing-Ping; Cai, Wu-Peng; Liang, Jian-Hua; Zhou, Xiao-Song; Long, Xing-Gui

2014-09-01

408

SURFACE MODIFICATION OF ZIRCALOY-4 SUBSTRATES WITH NICKEL ZIRCONIUM INTERMETALLICS  

SciTech Connect

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.

Luscher, Walter G.; Gilbert, Edgar R.; Pitman, Stan G.; Love, Edward F.

2013-02-01

409

Zirconium phosphate waste forms for low-temperature stabilization of cesium-137-containing waste streams  

SciTech Connect

Novel chemically bonded phosphate ceramics are being developed and fabricated for low-temperature stabilization and solidification of waste streams that are not amenable to conventional high-temperature stabilization processes because volatiles are present in the wastes. A composite of zirconium-magnesium phosphate has been developed and shown to stabilize ash waste contaminated with a radioactive surrogate of {sup 137}Cs. Excellent retainment of cesium in the phosphate matrix system was observed in Toxicity Characteristic Leaching Procedure tests. This was attributed to the capture of cesium in the layered zirconium phosphate structure by intercalation ion-exchange reaction. But because zirconium phosphate has low strength, a novel zirconium/magnesium phosphate composite waste form system was developed. The performance of these final waste forms, as indicated by compression strength and durability in aqueous environments, satisfy the regulatory criteria. Test results indicate that zirconium-magnesium-phosphate-based final waste forms present a viable technology for treatment and solidification of cesium-contaminated wastes.

Singh, D.; Wagh, A.S.; Tlustochowicz

1996-04-01

410

Zirconium-based alloys, nuclear fuel rods and nuclear reactors including such alloys, and related methods  

DOEpatents

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.

Mariani, Robert Dominick

2014-09-09

411

Synthesis of zirconium tungstate-zirconia core-shell composite particles  

SciTech Connect

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.

Khazeni, Nasser, E-mail: khazeni.n@gmail.com [Chemical Engineering Department, Middle East Technical University, Ankara 06531 (Turkey)] [Chemical Engineering Department, Middle East Technical University, Ankara 06531 (Turkey); Mavis, Bora, E-mail: bmavis@hacettepe.edu.tr [Mechanical Engineering Department, Hacettepe University, Beytepe Ankara 06800 (Turkey)] [Mechanical Engineering Department, Hacettepe University, Beytepe Ankara 06800 (Turkey); Guenduez, Guengoer, E-mail: ggunduz@metu.edu.tr [Chemical Engineering Department, Middle East Technical University, Ankara 06531 (Turkey)] [Chemical Engineering Department, Middle East Technical University, Ankara 06531 (Turkey); Colak, Uner, E-mail: ucolak@hacettepe.edu.tr [Nuclear Engineering Department, Hacettepe University, Beytepe Ankara 06800 (Turkey)] [Nuclear Engineering Department, Hacettepe University, Beytepe Ankara 06800 (Turkey)

2011-11-15

412

Pore-size tunable mesoporous zirconium organophosphonates with chiral L-proline for enzyme adsorption.  

PubMed

Mesoporous zirconium organophosphonates with a tunable mesopore (pore diameter: from 4.8 to 16.3 nm) were synthesized through co-condensation of ZrCl4 and 1-phosphomethylproline (H3PMP) with the aid of organic additives in the presence of an anionic surfactant (sodium dodecyl sulfate) under weak acidic conditions. The organic additives, tetrahydrofuran, can effectively strengthen the assembly of ZrCl4 and H3PMP around the surfactant micelles through decreasing the hydrolysis and condensation rate of ZrCl4. The results of the N2 sorption isotherm and SEM image show that zirconium phosphate with a bimodal structure is formed by calcination of mesoporous zirconium organophosphonate. Mesoporous zirconium organophosphonates can effectively adsorb lysozyme (Lz) and papain, and the adsorption equilibrium for Lz can be reached within 30 min. The adsorption capacity for Lz and papain can reach as high as 438 and 297 mg/g, respectively. Furthermore, Lz adsorbed on mesoporous zirconium organophosphonates can retain its structural conformation as in its free state, and no leaching of Lz from the solid was observed when shaking the Lz-loaded solid in a buffer solution. Also, the existence of L-proline in the mesopore could help the adsorption of papain at a pH value lower than the pI of papain. PMID:17696427

Shi, Xin; Liu, Jian; Li, Congming; Yang, Qihua

2007-09-17

413

A Lotus japonicus mutant defective in nitrate uptake is also affected in the nitrate response to nodulation.  

PubMed

A chlorate-resistant mutant (Ljclo1) of the model legume Lotus japonicus was identified that showed normal levels of nitrate reductase enzyme activity but had decreased uptake of nitrate, as determined from nitrate depletion and electrophysiological measurements. The data suggest that the mutant could be affected specifically in the low-affinity but not in the high-affinity nitrate transport system, and also showed decreased uptake of chlorate. Back-crosses of the mutant plant to the wild type indicated that it is affected in a single Mendelian recessive trait. Thus, the mutation produced in Ljclo1 may be related to some of the low-affinity nitrate transporters or to a regulatory mechanism associated with nitrate/chlorate uptake. Both size and chlorophyll content in young leaves of the mutant plants were significantly reduced compared to the wild type. In addition, nodulation performance of the mutant plants was similar to the wild type in the absence of any exogenous nitrate. However, the nodule:root biomass ratio in mutant plants was considerably reduced in the presence of 1-2 mm nitrate. The levels of several transcripts for nitrate transport and assimilation genes were determined for the wild type and mutant plants and were slightly different. The results suggest interdependence between nitrate uptake, plant growth and nodulation in Ljclo1 mutant plants. PMID:24673996

Pal'ove-Balang, P; García-Calderón, M; Pérez-Delgado, C M; Pavlovkin, J; Betti, M; Márquez, A J

2015-01-01

414

Anisole nitration during gamma-irradiation of aqueous nitrite and nitrate solutions: Free radical versus ionic mechanisms  

SciTech Connect

Radiolytic aromatic nitration mechanisms in the condensed phase are ubiquitous, and especially of interest in atmospheric aerosol chemistry, water treatment by advanced oxidation technologies, and nuclear fuel reprocessing. Here, the radiolytically-induced nitration reactions of anisole, the simplest aryl alkyl ether, were investigated in ?-irradiated acidic nitrate solution, and in neutral nitrate and nitrite solutions. The nitrated anisole product distribution was the same with and without radiation in acidic solution, although more products were formed as a result of irradiation. This suggests that the mechanism of nitration in acidic solution is nitronium ion- induced electrophilic aromatic substitution. The rate of production of nitrated products in neutral nitrate solution was much lower, although the distribution of isomers was similar to that expected for nitronium ion electrophilic nitration. In contrast, the product distribution in neutral nitrite solution approached a statistically random substitution pattern, suggesting a non-electrophilic free radical reaction involving •NO2 radical. When hydroxyl radical (•OH) was scavenged by varying the initial nitrite concentration, the concentration of nitrated products increased with increasing nitrite, indicating that the reaction was probably one of direct •NO2 radical addition. However, this latter mechanism will not be important in acidic solutions, such as those often encountered in atmospheric aerosols or ?-irradiated nuclear fuel reprocessing solutions, due to low amounts of produced •NO2 radical and the low reaction rate constants for the •NO2 radical with aromatic compounds.

Gracy Elias; Bruce J. Mincher; Leigh R. Martin; Stephen P. Mezyk; Thomas Cullen

2010-04-01

415

Glucose elevates NITRATE TRANSPORTER2.1 protein levels and nitrate transport activity independently of its HEXOKINASE1-mediated stimulation of NITRATE TRANSPORTER2.1 expression.  

PubMed

Mineral nutrient uptake and assimilation is closely coordinated with the production of photosynthate to supply nutrients for growth. In Arabidopsis (Arabidopsis thaliana), nitrate uptake from the soil is mediated by genes encoding high- and low-affinity transporters that are transcriptionally regulated by both nitrate and photosynthate availability. In this study, we have studied the interactions of nitrate and glucose (Glc) on gene expression, nitrate transport, and growth using glucose-insensitive2-1 (gin2-1), which is defective in sugar responses. We confirm and extend previous work by showing that HEXOKINASE1-mediated oxidative pentose phosphate pathway (OPPP) metabolism is required for Glc-mediated NITRATE TRANSPORTER2.1 (NRT2.1) expression. Treatment with pyruvate and shikimate, two products derived from intermediates of the OPPP that are destined for amino acid production, restores wild-type levels of NRT2.1 expression, suggesting that metabolites derived from OPPP metabolism can, together with Glc, directly stimulate high levels of NRT2.1 expression. Nitrate-mediated NRT2.1 expression is not influenced by gin2-1, showing that Glc does not influence NRT2.1 expression through nitrate-mediated mechanisms. We also show that Glc stimulates NRT2.1 protein levels and transport activity independently of its HEXOKINASE1-mediated stimulation of NRT2.1 expression, demonstrating another possible posttranscriptional mechanism influencing nitrate uptake. In gin2-1 plants, nitrate-responsive biomass growth was strongly reduced, showing that the supply of OPPP metabolites is essential for assimilating nitrate for growth. PMID:24272701

de Jong, Femke; Thodey, Kate; Lejay, Laurence V; Bevan, Michael W

2014-01-01

416

Sustainability of natural attenuation of nitrate in agricultural aquifers  

USGS Publications Warehouse

Increased concentrations of nitrate in groundwater in agricultural areas, coinciding with increased use of chemical and organic fertilizers, have raised concern because of risks to environmental and human health. At some sites, these problems are mitigated by natural attenuation of nitrate as a result of microbially mediated reactions. Results from U.S. Geological Survey (USGS) research under the National Water-Quality Assessment (NAWQA) program show that reactions of dissolved nitrate with solid aquifer minerals and organic carbon help lower nitrate concentrations in groundwater beneath agricultural fields. However, increased fluxes of nitrate cause ongoing depletion of the finite pool of solid reactants. Consumption of the solid reactants diminishes the capacity of the aquifer to remove nitrate, calling into question the long-term sustainability of these natural attenuation processes.

Green, Christopher T.; Bekins, Barbara A.

2010-01-01

417

Sulfate and nitrate collected by filter sampling near the tropopause  

NASA Technical Reports Server (NTRS)

Filter samples collected near the tropopause with an F-106 aircraft and two Boeing 747 aircraft were analyzed for sulfate and nitrate ion content. Within the range of routine commercial flight altitudes (at or below 12.5 km), stratospheric mass mixing ratios for the winter-spring group averaged 0.26 ppbm for sulfate and 0.35 ppbm for nitrate. For the summer-fall group, stratosphere mixing ratios averaged 0.13 ppbm and 0.25 ppbm for sulfate and nitrate, respectively. Winter-spring group tropospheric mass mixing ratios averaged 0.08 ppbm for sulfate and 0.10 ppbm for nitrate, while summer-fall group tropospheric mixing ratios averaged 0.05 ppbm for sulfate and 0.08 ppbm for nitrate. Correlations of the filter data with available ozone data suggest that the sulfate and nitrate are transported from the stratosphere to the troposphere.

Humenik, F. M.; Lezberg, E. A.; Otterson, D. A.

1980-01-01

418

Computational Design of Metal-Organic Frameworks Based on Stable Zirconium Building Units for Storage and Delivery of Methane  

E-print Network

between 65 and 5.8 bar is 167 cc(STP)/cc (0.215 g/g), the highest among zirconium-based MOFs. HighComputational Design of Metal-Organic Frameworks Based on Stable Zirconium Building Units-organic framework (MOF) with high volumetric deliverable capacity for methane was synthesized after being identified

419

Hartree-Fock-Bogoliubov calculations in coordinate space: Neutron-rich sulfur, zirconium, cerium, and samarium isotopes  

E-print Network

Hartree-Fock-Bogoliubov calculations in coordinate space: Neutron-rich sulfur, zirconium, cerium study the properties of neutron-rich zirconium 102,104 Zr , cerium 152 Ce , and samarium 158,160 Sm of nuclear iso- topes still to be explored with new radioactive ion beam facilities [1]. Another limit

Teran, Edgar

420

Nitrate Paradigm Does Not Hold Up for Sugarcane  

PubMed Central

Modern agriculture is based on the notion that nitrate is the main source of nitrogen (N) for crops, but nitrate is also the most mobile form of N and easily lost from soil. Efficient acquisition of nitrate by crops is therefore a prerequisite for avoiding off-site N pollution. Sugarcane is considered the most suitable tropical crop for biofuel production, but surprisingly high N fertilizer applications in main producer countries raise doubt about the sustainability of production and are at odds with a carbon-based crop. Examining reasons for the inefficient use of N fertilizer, we hypothesized that sugarcane resembles other giant tropical grasses which inhibit the production of nitrate in soil and differ from related grain crops with a confirmed ability to use nitrate. The results of our study support the hypothesis that N-replete sugarcane and ancestral species in the Andropogoneae supertribe strongly prefer ammonium over nitrate. Sugarcane differs from grain crops, sorghum and maize, which acquired both N sources equally well, while giant grass, Erianthus, displayed an intermediate ability to use nitrate. We conclude that discrimination against nitrate and a low capacity to store nitrate in shoots prevents commercial sugarcane varieties from taking advantage of the high nitrate concentrations in fertilized soils in the first three months of the growing season, leaving nitrate vulnerable to loss. Our study addresses a major caveat of sugarcane production and affords a strong basis for improvement through breeding cultivars with enhanced capacity to use nitrate as well as through agronomic measures that reduce nitrification in soil. PMID:21552564

Robinson, Nicole; Brackin, Richard; Vinall, Kerry; Soper, Fiona; Holst, Jirko; Gamage, Harshi; Paungfoo-Lonhienne, Chanyarat; Rennenberg, Heinz; Lakshmanan, Prakash; Schmidt, Susanne

2011-01-01

421

Physiologie vgtale Mesure de l'activit nitrate rductase  

E-print Network

Physiologie végétale Mesure de l'activité nitrate réductase durant le cycle cultural du soja, assimilation du nitrate et fixation de l'azote de l'air, ont été étudiées chez le soja (cv Hodgson), inoculé avec Bradyrhizobium japonicum USDA 138. L'évolution des 2 activités enzymatiques, nitrate réductase et

Paris-Sud XI, Université de

422

Electrochemical cell having an alkali-metal-nitrate electrode  

DOEpatents

A power-producing secondary electrochemical cell includes a molten alkali metal as the negative-electrode material and a molten-nitrate salt as the positive-electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali-metal-ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium ..beta..'' alumina.

Roche, M.F.; Preto, S.K.

1982-06-04

423

Dissimilatory and Assimilatory Nitrate Reduction in the Purple Photosynthetic Bacteria  

Microsoft Academic Search

Nitrate reduction can be either a dissimilatory or assimilatory process. Nitrate reduction to nitrogen gas via a series of\\u000a nitrogen oxide intermediates is a dissimilatory process termed denitrification. Denitrification is common among the purple\\u000a photosynthetic bacteria. While some reduce nitrate to nitrogen gas many are missing components of the denitrification pathway.\\u000a In the complete denitrifiers, denitrification can be used as

James P. Shapleigh

424

Evaluation of nitrate reductase activity in Rhizobium japonicum  

SciTech Connect

Nitrate reductase activity was evaluated by four approaches, using four strains of Rhizobium japonicum and 11 chlorate-resistant mutants of the four strains. It was concluded that in vitro assays with bacteria or bacteroids provide the most simple and reliable assessment of the presence or absence of nitrate reductase. Nitrite reductase activity with methyl viologen and dithionite was found, but the enzyme activity does not confound the assay of nitrate reductase. 18 references

Streeter, J.G.; DeVine, P.J.

1983-08-01

425

Eutectic composite explosives containing ammonium nitrate  

SciTech Connect

The eutectic of ammonium nitrate (AN), the ammonium salt of 3,5-dinitro-1,2,4-triazole was prepared and its sensitivity and performance were studied. It was found that this AN formulation was unusual in that it performed ideally at small diameter, which indicated that it was a monomolecular explosive. Sensitivity tests included type 12 impact, Henkin thermal and wedge tests, and performance tests included rate stick/plate dent, cylinder, and aquarium tests. Results were compared with calculations, standard explosives, and another eutectic, ethylendiamine dinitrate (EDD)/AN.

Stinecipher, M.M.

1981-01-01

426

2-Cyano-quinolin-1-ium nitrate.  

PubMed

A proton is transferred from the nitric acid to the N atom of 2-cyano-quinoline during crystallization, resulting in the formation of the title salt, C(10)H(7)N(2) (+)·NO(3) (-). The quinolinium ring system is approximately planar, with a maximum deviation of 0.013?(3)?Å. In the crystal, a very asymmetric bifurcated N-H?(O,O) hydrogen bond to two O atoms of an adjacent nitrate anion occurs, generating an R(2) (1)(4) ring motif. C-H?O hydrogen bonds link the ions into sheets stacking along the a axis. PMID:21588937

Loh, Wan-Sin; Hemamalini, Madhukar; Fun, Hoong-Kun

2010-01-01

427

Nitrate Leaching from Intensive Fiber Production on Abandoned Agricultural Land  

SciTech Connect

Paper outlines nitrate leaching results of loblolly pine and sweet gum that were grown with irrigation, continuous fertilization and insect pest control on a year old abandoned peanut field. Wells and tension lysimeters were used to measure nitrate in soil moisture and groundwater on three replicate transects for two years. Groundwater nitrate concentration beneath the minimum treatment was much higher than the maximum treatment and old field. All three treatments often exceeded the drinking water standard. Forest and lake edge had low levels while the soil moisture nitrate concentrations in the two plantation treatments were much higher than the old field.

Williams, T.M.

1999-01-01

428

Simultaneous removal of nitrate and heavy metals by iron metal*  

PubMed Central

Great attention should be paid now to simultaneously removing common pollutants, especially inorganic pollutants such as nitrate and heavy metals, as individual removal has been investigated extensively. Removing common pollutants simultaneously by iron metal is a very effective alternative method. Near neutral pH, heavy metals, such as copper and nickel, can be removed rapidly by iron metal, while nitrate removal very much slower than that of copper and nickel, and copper can accelerate nitrate removal when both are removed simultaneously. Even a little amount of copper can enhance nitrate removal efficiently. Different mechanisms of these contaminants removal by iron metal were also discussed. PMID:15822139

Hao, Zhi-wei; Xu, Xin-hua; Jin, Jian; He, Ping; Liu, Yong; Wang, Da-hui

2005-01-01

429

Endogenously Nitrated Proteins in Mouse Brain: Links To Neurodegenerative Disease  

SciTech Connect

Increased nitrotyrosine modification of proteins has been documented in multiple pathologies in a variety of tissue types; emerging evidence suggests its additional role in redox regulation of normal metabolism. In order to identify proteins sensitive to nitrating conditions in vivo, a comprehensive proteomic dataset identifying 7,792 proteins from whole mouse brain, generated by LC/LC-MS/MS analyses, was used to identify nitrated proteins. This analysis resulted in identification of 31 unique nitrotyrosine sites within 29 different proteins. Over half of the nitrated proteins identified have been reported to be involved in Parkinson's disease, Alzheimer's disease, or other neurodegenerative disorders. Similarly, nitrotyrosine immunoblots of whole brain homogenates show that treatment of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), an experimental model of Parkinson's disease, induces increased nitration of the same protein bands observed to be nitrated in brains of untreated animals. Comparing sequences and available high resolution structures around nitrated tyrosines with those of unmodified sites indicates a preference of nitration in vivo for surface accessible tyrosines in loops, characteristics consistent with peroxynitrite-induced tyrosine modification. More striking is the five-fold greater nitration of tyrosines having nearby basic sidechains, suggesting electrostatic attraction of basic groups with the negative charge of peroxynitrite. Together, these results suggest that elevated peroxynitrite generation plays a role in neurodegenerative changes in the brain and provides a predictive tool of functionally important sites of nitration.

Sacksteder, Colette A.; Qian, Weijun; Knyushko, Tanya V.; Wang, Haixing H.; Chin, Mark H.; Lacan, Goran; Melega, William P.; Camp, David G.; Smith, Richard D.; Smith, Desmond J.; Squier, Thomas C.; Bigelow, Diana J.

2006-07-04

430

Hydrothermal oxidation of organic wastes using reclaimed ammonium nitrate  

SciTech Connect

Ammonium nitrate is being studied as an alternative for ammonium perchlorate as an oxidizing agent in Department of Defense 1.1 and 1.3 rocket propellants. Use of ammonium nitrate would eliminate the HCl produced by ammonium perchlorate upon thermal decomposition. To stabilize the ammonium nitrate, which suffers from phase instability, potassium dinitramide (KDN) is added. This increased use of ammonium nitrate will ultimately create a need for environmentally responsible processes to reuse ammonium nitrate extracted from demilitarized rocket motors. Ammonium Nitrate was investigated as an oxidizing agent for methanol, acetic acid and phenol. High removal of organic, ammonia and nitrate was achieved at stoichiometric concentrations. The oxidation of ammonia by nitrate was much faster than the oxidation of either methanol or acetic acid. Phenol, however, was in strong competition with ammonia for the oxidizer (nitrate). Nitrogen products included N{sub 2}, N{sub 2}O, NO{sub 2{sup {minus}}} as well as toxic NO and trace amounts of NO{sub 2}. Carbon products were CO{sub 2}, HCO{sub 3{sup {minus}}}, CO{sub 3}{sup 2{minus}}, and CO.

Proesmans, P.I.; Luan, L.; Buelow, S.J.

1996-04-01

431

Impact of nitrate dose on toluene degradation under denitrifying condition.  

PubMed

In this study, we investigated the impact of nitrate dose on toluene degradation by Pseudomonas putida to elucidate the upper limit of nitrate concentration and whether an optimum ratio of nitrate to toluene concentration exists. Batch microcosm studies were conducted in order to monitor toluene degradation for various ratios (2-20) of nitrate to toluene with nitrate concentrations ranging from 0 to 700 mg?L(-1) for a given toluene concentration of 50 and 25 mg?L(-1) during 4-day (short term) and 14-day (long term) incubation time, respectively. The short-term study revealed that nitrate concentration of 500 mg?L(-1) was toxic to bacteria and the optimum concentration was 300 mg?L(-1) yielding the highest toluene degradation rate (0.083 mg?L(-1)?h(-1)). In the batch study of long term, toluene degradation was limited to 6 days after which the nitrate at 50 mg?L(-1) was depleted, indicating that nitrate was a necessary electron acceptor. For both batch studies, an optimum ratio of 6 was found yielding the highest toluene degradation rate. This indicates that an appropriate nitrate dose is essential for efficient degradation of toluene when bioremediation of groundwater contaminated with toluene is under consideration. PMID:23504564

Kim, Dong-Ju; Park, Mee-Rye; Lim, Dae-Soon; Choi, Jae-Woo

2013-05-01

432

The nitrate/proton antiporter AtCLCa mediates nitrate accumulation in plant vacuoles.  

PubMed

Nitrate, the major nitrogen source for most plants, is widely used as a fertilizer and as a result has become a predominant freshwater pollutant. Plants need nitrate for growth and store most of it in the central vacuole. Some members of the chloride channel (CLC) protein family, such as the torpedo-fish ClC-0 and mammalian ClC-1, are anion channels, whereas the bacterial ClC-ec1 and mammalian ClC-4 and ClC-5 have recently been characterized as Cl-/H+ exchangers with unknown cellular functions. Plant members of the CLC family are proposed to be anion channels involved in nitrate homeostasis; however, direct evidence for anion transport mediated by a plant CLC is still lacking. Here we show that Arabidopsis thaliana CLCa (AtCLCa) is localized to an intracellular membrane, the tonoplast of the plant vacuole, which is amenable to electrophysiological studies, and we provide direct evidence for its anion transport ability. We demonstrate that AtCLCa is able to accumulate specifically nitrate in the vacuole and behaves as a NO3-/H+ exchanger. For the first time, to our knowledge, the transport activity of a plant CLC is revealed, the antiporter mechanism of a CLC protein is investigated in a native membrane system, and this property is directly connected with its physiological role. PMID:16878138

De Angeli, A; Monachello, D; Ephritikhine, G; Frachisse, J M; Thomine, S; Gambale, F; Barbier-Brygoo, H

2006-08-24

433

[Effect of nitrate and cytokinin on nitrate reductase activity in isolated corncockle embryos].  

PubMed

The effects of cytokinin and nitrate on the activity of nitrate reductase (NR) in isolated embryos of Agrostemma githago L. were studied. It was shown that the effects of cytokinin and NO-3 on the induction of NR is additive during 8, 12 and 18 hrs of embryos incubation in the solutions of the two inducers. Anticytokinin decreased the cytokinin induced NR by 35--39% and had no effect on the NR induction by nitrate. The substrate and hormonal induction of NR differed in the duration of the lag period. This difference dependent on the physiological state of the embryos at the beginning of incubation. The data obtained are indicative of the independence of cytokinin and NO-3 effects on the NR synthesis in isolated embryos of Agrostemma githago L. Abscisic acid supressed cytokinin- and nitrate-induced NR and had practically no effect on total incorporation of the label into the protein. It is assumed that the induced synthesis of the protein is more sensitive to the action of abscisic acid that the total protein synthesis. PMID:155476

Kuznetsov, V V; Kuznetsov, V V; Kulaeva, O N

1979-04-01

434

Developmental stage-specific and nitrate-independent regulation of nitrate reductase gene expression in rapeseed.  

PubMed Central

cDNA clones for two isogenes of nitrate reductase (NR) have been isolated from rapeseed (Brassica napus L.) androgenetic haploid embryos induced by microspore culture. NR mRNA accumulation can be detected by northern hybridization at 14 d after culture initiation when embryos develop to the heart/torpedo-shaped stage. Whole-mount in situ hybridization experiments demonstrate that the mRNA accumulation is developmental stage specific. In addition, even when cultured in media containing no nitrate, embryos accumulated NR mRNA to almost the same level as the control. This indicates the unique regulation of NR in embryogenesis in which NR mRNA transcription is activated in a developmental stage-specific manner that is independent of nitrate induction. In zygotic embryogenesis, a stage-specific accumulation of NR mRNA was also observed. By contrast, the obvious effect of nitrate on NR expression that has been reported in many plant species was also confirmed in rapeseed leaf. Quantitative combined reverse transcription-polymerase chain reaction analysis suggests that the flexible and variable regulation of NR expression, which is organ specific, nitrogen metabolite specific, and developmental stage specific, is caused principally by regulation of one major structural gene. PMID:8685274

Fukuoka, H; Ogawa, T; Minami, H; Yano, H; Ohkawa, Y

1996-01-01

435

Molecular basis of nitrate uptake by the plant nitrate transporter NRT1.1  

PubMed Central

Summary The NRT1/PTR family of proton-coupled transporters are responsible for nitrogen assimilation in eukaryotes and bacteria through the uptake of peptides. However, in the majority of plant species members of this family have evolved to transport nitrate as well as additional secondary metabolites and hormones. In response to falling nitrate levels, NRT1.1 is phosphorylated on an intracellular threonine that switches the transporter from a low to high affinity state. Here we present both the apo and nitrate bound crystal structures of Arabidopsis thaliana NRT1.1, which together with in vitro binding and transport data identify a key role for His356 in nitrate binding. Our data support a model whereby phosphorylation increases structural flexibility and in turn the rate of transport. Comparison with peptide transporters further reveals how the NRT1/PTR family has evolved to recognize diverse nitrogenous ligands, whilst maintaining elements of a conserved coupling mechanism within this superfamily of nutrient transporters. PMID:24572366

Parker, Joanne L.; Newstead, Simon

2014-01-01

436

PRODUCTION OF ORGANIC NITRATES FROM HYDROXYL AND NITRATE RADICAL REACTION WITH PROPYLENE  

EPA Science Inventory

Measurements of the gas-phase production rates of alpha-nitratoacetone, propylene glycol dinitrate, 2-hydroxy propyl nitrate, and 2-nitrato propyl alcohol (2-NPA) in a C3H6/N2O5/air dark reaction and a C3H6/NOX/air irradiation are reported. The probable operative reaction mechani...

437

Impacts of drainage water management on subsurface drain flow, nitrate concentration, and nitrate loads in Indiana  

EPA Science Inventory

Drainage water management is a conservation practice that has the potential to reduce drainage outflow and nitrate (NO3) loss from agricultural fields while maintaining or improving crop yields. The goal of this study was to quantify the impact of drainage water management on dra...

438

Hypersensitivity pneumonitis and exposure to zirconium silicate in a young ceramic tile worker.  

PubMed

We describe a nonsmoking ceramic tile worker 25 yr of age who developed a worsening dry cough and dyspnea after 3.5 yr as a sorter and glazer of tiles. Open lung biopsy revealed an intense granulomatous interstitial pneumonia with mild fibrosis, compatible with hypersensitivity pneumonitis, and numerous very small birefringent crystals around the terminal airways and occasionally in granulomas. Pulmonary particle analysis revealed an inhaled dust burden nearly 100-fold the normal background level, mainly consisting of clay minerals and zirconium silicate. The patient had no history or clinical or laboratory findings suggesting any organic etiologic agent. A sarcoid granulomatosis type of chronic pulmonary hypersensitivity reaction is known after long-term exposure to zirconium, but this case demonstrates that zirconium can also cause an acute and fulminant allergic alveolitislike hypersensitivity reaction. PMID:8214930

Liippo, K K; Anttila, S L; Taikina-Aho, O; Ruokonen, E L; Toivonen, S T; Tuomi, T

1993-10-01

439

Hydrogen Embrittlement in Zirconium: a Quasi-Continuum Density Functional Theory Study  

NASA Astrophysics Data System (ADS)

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.

Peng, Q.

2012-02-01

440

Theoretical study of the reaction between 2,2???,4???-trihydroxyazobenzene-5-sulfonic acid and zirconium  

USGS Publications Warehouse

Zirconium reacts with 2,2???,4???-trihydroxyazobenzene-5-sulfonic acid in acid solutions to Form two complexes in which the ratios of dye to zirconium are 1 to 1 and 2 to 1. Both complexes are true chelates, with zirconium acting as a bridge between the two orthohydroxy dye groups. Apparent equilibrium constants for the reactions to form each of the complexes are determined. The reactions are used as a basis for the determination of the active component in the dye and a graphical method for the determination of reagent purity is described. Four absorption spectra covering the wave length region from 350 to 750 m?? are given, which completely define the color system associated with the reactions in solutions where the hydrochloric acid concentration ranges from 0.0064N to about 7N.

Fletcher, M.H.

1960-01-01

441

Simulating the corrosion of zirconium alloys in the water coolant of VVER reactors  

NASA Astrophysics Data System (ADS)

A model for predicting the corrosion of cladding zirconium alloys depending on their composition and operating conditions is proposed. Laws of thermodynamics and chemical kinetics of the reactions through which the multicomponent zirconium alloy is oxidized in the reactor coolant constitute the physicochemical heart of the model. The developed version of the model is verified against the results obtained from tests of fuel rod claddings made of commercial-grade and experimental zirconium alloys carried out by different researchers under autoclave and reactor conditions. It is shown that the proposed model adequately describes the corrosion of alloys in coolants used at nuclear power stations. It is determined that, owing to boiling of coolant and its acidification in a VVER-1200 reactor, Zr-1% Nb alloys with additions of iron and oxygen must be more resistant to corrosion than the commercial-grade alloy E110.

Kritskii, V. G.; Berezina, I. G.; Motkova, E. A.

2013-07-01

442

Ion processing of zirconium ceramics by high-power pulsed beams  

NASA Astrophysics Data System (ADS)

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.

Ghyngazov, S. A.; Vasil'ev, I. P.; Surzhikov, A. P.; Frangulyan, T. S.; Chernyavskii, A. V.

2015-01-01

443

Review of Cernox™ (Zirconium Oxy-Nitride) Thin-Film Resistance Temperature Sensors  

NASA Astrophysics Data System (ADS)

Cernox™ resistance thermometers were commercially introduced in 1993. The Cernox™ temperature-sensing element is fabricated from zirconium reactively sputtered in a nitrogen-oxygen atmosphere. The resulting thin film is comprised of conducting zirconium nitride embedded within a zirconium oxide nonconducting matrix. This material has a negative temperature coefficient of resistance making it useful as a temperature sensor. The ratio of conducting to nonconducting material can be varied to tailor the sensor to a given temperature range. A single device can be fabricated for use from below 0.3 K to 420 K. Cernox™ temperature sensors possess many attributes desirable in a temperature sensor including high sensitivity, excellent short-term and long-term stability, small physical size, fast thermal response and small calibration shifts when exposed to magnetic fields or ionizing radiation. This paper presents a review of Cernox™ temperature sensors with regard to their physical, thermometric and operational properties and environmental effects.

Courts, S. Scott; Swinehart, Philip R.

2003-09-01

444

Determination of fluoride in water - A modified zirconium-alizarin method  

USGS Publications Warehouse

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.

Lamar, W.L.

1945-01-01

445

A comparative study between two citrus rootstocks: Effect of nitrate on the root morpho-topology and net nitrate uptake  

Microsoft Academic Search

Root morpho-topology and net nitrate uptake of two citrus seedlings, Volkamer Lemon and Carrizo Citrange, grown at two nitrogen supplies (NO3-N 5 µM and 1000 µM, respectively) were studied. Root morphological and topological parameters were gauged by an image-specific analysis system (WinRHIZO). Net nitrate uptake was estimated using the nitrate depletion method. The main findings showed that Carrizo seedlings had a dichotomous

Agostino Sorgonà; Maria Rosa Abenavoli; Giovanni Cacco

2005-01-01

446

Nitro derivatives of the thiophene series. 4. Nitration of thiophene derivatives with metal nitrates in acetic anhydride  

Microsoft Academic Search

The nitration of 2-formylthiophene, 2-acetothienone, and unsaturated ketones of the thiophene series with copper and aluminum nitrates in acetic anhydride at various temperatures was studied. At low temperatures 2-acetothienone gives a mixture of 4- and 5-nitro isomers, while 2-formylthipphene gives only a 5-nitro-substituted compound in the diacetate form; ?,?-unsaturated ketones are not nitrated under these conditions. When the reaction is

Yu. D. Churkin; L. V. Panfilova; V. D. Lugovoi; N. V. Boiko

1981-01-01

447

Solid-phase zirconium and fluoride species in alkaline zircaloy cladding waste at Hanford.  

PubMed

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 ?m in length. These results provide waste process planners the speciation data needed to develop disposal processes for this waste. PMID:24976128

Reynolds, Jacob G; Huber, Heinz J; Cooke, Gary A; Pestovich, John A

2014-08-15

448

Bayesian model selection validates a biokinetic model for zirconium processing in humans  

PubMed Central

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

2012-01-01

449

Influence de la teneur en nitrate sur l'volution des activits nitrate rductase et nitrognase du  

E-print Network

Influence de la teneur en nitrate sur l'évolution des activités nitrate réductase et nitrogénase du'évolution des activités nitrate réductase et nitrogénase (réduction de l'acétylène) a été suivie au cours du cycle du fenugrec (Trigonella foenum-graecum L.) cultivé en plein champ avec et sans apport de nitrate

Paris-Sud XI, Université de

450

Effects of cathode potentials and nitrate concentrations on dissimilatory nitrate reductions by Pseudomonas alcaliphila in bioelectrochemical systems.  

PubMed

The effects of cathode potentials and initial nitrate concentrations on nitrate reduction in bioelectrochemical systems (BESs) were reported. These factors could partition nitrate reduction between denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Pseudomonas alcaliphilastrain MBR utilized an electrode as the sole electron donor and nitrate as the sole electron acceptor. When the cathode potential was set from -0.3 to -1.1 V (vs. Ag/AgCl) at an initial nitrate concentration of 100 mg NO3(-)-N/L, the DNRA electron recovery increased from (10.76 ± 1.6)% to (35.06 ± 0.99)%; the denitrification electron recovery decreased from (63.42 ± 1.32)% to (44.33 ± 1.92)%. When the initial nitrate concentration increased from (29.09 ± 0.24) to (490.97 ± 3.49) mg NO3(-)-N/L at the same potential (-0.9 V), denitrification electron recovery increased from (5.88 ± 1.08)% to (50.19 ± 2.59)%; the DNRA electron recovery declined from (48.79 ± 1.32)% to (16.02 ± 1.41)%. The prevalence of DNRA occurred at high ratios of electron donors to acceptors in the BESs and denitrification prevailed against DNRA under a lower ratio of electron donors to acceptors. These results had a potential application value of regulating the transformation of nitrate to N2 or ammonium in BESs for nitrate removal. PMID:25079419

Zhang, Wenjie; Zhang, Yao; Su, Wentao; Jiang, Yong; Su, Min; Gao, Ping; Li, Daping

2014-04-01

451

Interaction of sorbed Ni(II) ions with amorphous zirconium hydrogen phosphate  

NASA Astrophysics Data System (ADS)

Samples of amorphous zirconium hydrogen phosphate with different zirconium and phosphorus concentrations in hydrogen and nickel-substituted forms are studied by means of electronic, 31P NMR, and impedance spectroscopy. It is shown that Ni(II) ? H+ ion exchange is accompanied by the hydrolysis of sorbed cations and the formation of complexes with the dihydro- and hydrophosphate groups of the inorganic ionite. It is found that the coordination environment of Ni(II) in the sorbent phase includes 2-4 fragments of phosphate groups, along with OH groups and water molecules.

Dzyazko, Yu. S.; Trachevskii, V. V.; Rozhdestvenskaya, L. M.; Vasilyuk, S. L.; Belyakov, V. N.

2013-05-01

452

Corrosion of aluminides by molten nitrate salt  

SciTech Connect

The corrosion of titanium-, iron-, and nickel-based aluminides by a highly aggressive, oxidizing NaNO{sub 3}(-KNO{sub 3})-Na{sub 2}O{sub 2} has been studied at 650{degree}C. It was shown that weight changes could be used to effectively evaluate corrosion behavior in the subject nitrate salt environments provided these data were combined with salt analyses and microstructural examinations. The studies indicated that the corrosion of relatively resistant aluminides by these nitrate salts proceeded by oxidation and a slow release from an aluminum-rich product layer into the salt at rates lower than that associated with many other types of metallic materials. The overall corrosion process and resulting rate depended on the particular aluminide being exposed. In order to minimize corrosion of nickel or iron aluminides, it was necessary to have aluminum concentrations in excess of 30 at. %. However, even at a concentration of 50 at. % Al, the corrosion resistance of TiAl was inferior to that of Ni{sub 3}Al and Fe{sub 3}Al. At higher aluminum concentrations, iron, nickel, and iron-nickel aluminides exhibited quite similar weight changes, indicative of the principal role of aluminum in controlling the corrosion process in NaNO{sub 3}(-KNO{sub 3})-Na{sub 2}O{sub 2} salts. 20 refs., 5 figs., 3 tabs.

Tortorelli, P.F.; Bishop, P.S.

1990-01-01

453

Electrochemical processing of nitrate waste solutions  

SciTech Connect

The second phase of research performed at The Electrosynthesis Co., Inc. has demonstrated the successful removal of nitrite and nitrate from a synthetic effluent stream via a direct electrochemical reduction at a cathode. It was shown that direct reduction occurs at good current efficiencies in 1,000 hour studies. The membrane separation process is not readily achievable for the removal of nitrites and nitrates due to poor current efficiencies and membrane stability problems. A direct reduction process was studied at various cathode materials in a flow cell using the complete synthetic mix. Lead was found to be the cathode material of choice, displaying good current efficiencies and stability in short and long term tests under conditions of high temperature and high current density. Several anode materials were studied in both undivided and divided cell configurations. A divided cell configuration was preferable because it would prevent re-oxidation of nitrite by the anode. The technical objective of eliminating electrode fouling and solids formation was achieved although anode materials which had demonstrated good stability in short term divided cell tests corroded in 1,000 hour experiments. The cause for corrosion is thought to be F[sup [minus

Genders, D.; Weinberg, N.; Hartsough, D. (Electrosynthesis Co., Inc., Cheektowaga, NY (United States))

1992-10-07

454

Nuclear Magnetic Resonance Studies of Amorphous Nickel-Zirconium Hydrides.  

NASA Astrophysics Data System (ADS)

This research deals with one aspect of the scientific field of hydrogen in metals. The study of hydrogen in metals is technologically important for many reasons, among them is the use of hydrogen in metals to store energy. Hydrogen related energy technology is particularly attractive because hydrogen can be extracted from water, our most abundant resource, and can be used without any pollution. Metal hydrides may one day be widely used for automotive propulsion in cars, in batteries, and many other energy conversion devices. Amorphous NiZr is particularly interesting for hydrogen storage because high concentrations of hydrogen can be sorbed and desorbed repeatedly with only small deleterious effects to the metal. The motion of hydrogen and deuterium in amorphous nickel zirconium alloys (a-NiZr) has been studied and some properties of the local atomic structure in this amorphous metal have been deduced. This has been accomplished with nuclear magnetic resonance experiments measuring the spin lattice relaxation rate R_1 as a function of temperature and resonance frequency. Hydrogen can diffuse into and then through metals by hopping among interstitial positions. In a-NiZr the interstitial hydrogen positions are the centers of tetrahedra, with metal ions at the corners of the tetrahedra. Diffusive hydrogen motion occurs via classical over the barrier jumps, with a Gaussian distribution of activation energies for diffusion. The existence of a distribution of activation energies for diffusion is evidence supporting the densely packed random sphere model for the atomic structure of amorphous metals. The low temperature R_1 data is anomalous. Precipitation of Ni clusters out of the a-NiZr lattice may be occurring and causing unexpected spin lattice relaxation.

Hoke, Harris Clarence, Jr.

455

Ultrasonic texture characterization of aluminum, zirconium and titanium alloys  

SciTech Connect

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.

Anderson, A.J.

1997-10-08

456

Thermal properties of zirconium diboride -- transition metal boride solid solutions  

NASA Astrophysics Data System (ADS)

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.

McClane, Devon Lee

457

Occurrence and stability of trivalent zirconium in orthophosphate single crystals  

SciTech Connect

EPR spectroscopy has been used in investigations of the unusual 3+ valence state of zirconium. The EPR spectrum of Zr/sup 3 +/, which was initially observed as a parasitic signal in Fe-doped single crystals of ScPO/sub 4/, was definitively identified by preparing single crystals of ScPO/sub 4/ doped with isotopically enriched (94.6%)/sup 91/Zr. Single crystals of LuPO/sub 4/ and YPO/sub 4/ doped with both naturally abundant and isotopically enriched Zr were also grown and investigated. The EPR spectrum of Zr/sup 3 +/ could be observed at room temperature in the ''as-grown'' single crystals of both ScPO/sub 4/ and LuPO/sub 4/; and, accordingly, the 3+ state is stable at room temperature in these hosts. The spectrum of Zr/sup 3 +/ in the YPO/sub 4/ host could only be observed following a ..gamma.. irradiation at 77 K, and this spectrum decayed rapidly with increasing temperature. Axial spin-Hamiltonian parameters were determined for Zr/sup 3 +/ in all three hosts at a sample temperature of 77 K and at room temperature for the ScPO/sub 4/ and LuPO/sub 4/ hosts. In the case of the latter two hosts, the spin-Hamiltonian parameters were found to exhibit a small temperature dependence. The observed g values were not accounted for by previously published second-order expressions indicating that additional coupling mechanisms are operative.

Abraham, M.M.; Boatner, L.A.; Ramey, J.O.; Rappaz, M.

1984-12-15

458

Genetic and biochemical studies of nitrate reduction in Aspergillus nidulans.  

PubMed

1. In Aspergillus nidulans nitrate and nitrite induce nitrate reductase, nitrite reductase and hydroxylamine reductase, and ammonium represses the three enzymes. 2. Nitrate reductase can donate electrons to a wide variety of acceptors in addition to nitrate. These artificial acceptors include benzyl viologen, 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride, cytochrome c and potassium ferricyanide. Similarly nitrite reductase and hydroxylamine reductase (which are possibly a single enzyme in A. nidulans) can donate electrons to these same artificial acceptors in addition to the substrates nitrite and hydroxylamine. 3. Nitrate reductase can accept electrons from reduced benzyl viologen in place of the natural donor NADPH. The NADPH-nitrate-reductase activity is about twice that of reduced benzyl viologen-nitrate reductase under comparable conditions. 4. Mutants at six gene loci are known that cannot utilize nitrate and lack nitrate-reductase activity. Most mutants in these loci are constitutive for nitrite reductase, hydroxylamine reductase and all the nitrate-induced NADPH-diaphorase activities. It is argued that mutants that lack nitrate-reductase activity are constitutive for the enzymes of the nitrate-reduction pathway because the functional nitrate-reductase molecule is a component of the regulatory system of the pathway. 5. Mutants are known at two gene loci, niiA and niiB, that cannot utilize nitrite and lack nitrite-reductase and hydroxylamine-reductase activities. 6. Mutants at the niiA locus possess inducible nitrate reductase and lack nitrite-reductase and hydroxylamine-reductase activities. It is suggested that a single enzyme protein is responsible for the reduction of nitrite to ammonium in A. nidulans and that the niiA locus is the structural gene for this enzyme. 7. Mutants at the niiB locus lack nitrate-reductase, nitrite-reductase and hydroxylamine-reductase activities. It is argued that the niiB gene is a regulator gene whose product is necessary for the induction of the nitrate-utilization pathway. The niiB mutants either lack or produce an incorrect product and consequently cannot be induced. 8. Mutants at the niiribo locus cannot utilize nitrate or nitrite unless provided with a flavine supplement. When grown in the absence of a flavine supplement the activities of some of the nitrate-induced enzymes are subnormal. 9. The growth and enzyme characteristics of a total of 123 mutants involving nine different genes indicate that nitrate is reduced to ammonium. Only two possible structural genes for enzymes concerned with nitrate utilization are known. This suggests that only two enzymes, one for the reduction of nitrate to nitrite, the other for the reduction of nitrite to ammonium, are involved in this pathway. PMID:4382427

Pateman, J A; Rever, B M; Cove, D J

1967-07-01

459

Genetic and biochemical studies of nitrate reduction in Aspergillus nidulans  

PubMed Central

1. In Aspergillus nidulans nitrate and nitrite induce nitrate reductase, nitrite reductase and hydroxylamine reductase, and ammonium represses the three enzymes. 2. Nitrate reductase can donate electrons to a wide variety of acceptors in addition to nitrate. These artificial acceptors include benzyl viologen, 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride, cytochrome c and potassium ferricyanide. Similarly nitrite reductase and hydroxylamine reductase (which are possibly a single enzyme in A. nidulans) can donate electrons to these same artificial acceptors in addition to the substrates nitrite and hydroxylamine. 3. Nitrate reductase can accept electrons from reduced benzyl viologen in place of the natural donor NADPH. The NADPH–nitrate-reductase activity is about twice that of reduced benzyl viologen–nitrate reductase under comparable conditions. 4. Mutants at six gene loci are known that cannot utilize nitrate and lack nitrate-reductase activity. Most mutants in these loci are constitutive for nitrite reductase, hydroxylamine reductase and all the nitrate-induced NADPH-diaphorase activities. It is argued that mutants that lack nitrate-reductase activity are constitutive for the enzymes of the nitrate-reduction pathway because the functional nitrate-reductase molecule is a component of the regulatory system of the pathway. 5. Mutants are known at two gene loci, niiA and niiB, that cannot utilize nitrite and lack nitrite-reductase and hydroxylamine-reductase activities. 6. Mutants at the niiA locus possess inducible nitrate reductase and lack nitrite-reductase and hydroxylamine-reductase activities. It is suggested that a single enzyme protein is responsible for the reduction of nitrite to ammonium in A. nidulans and that the niiA locus is the structural gene for this enzyme. 7. Mutants at the niiB locus lack nitrate-reductase, nitrite-reductase and hydroxylamine-reductase activities. It is argued that the niiB gene is a regulator gene whose product is necessary for the induction of the nitrate-utilization pathway. The niiB mutants either lack or produce an incorrect product and consequently cannot be induced. 8. Mutants at the niiribo locus cannot utilize nitrate or nitrite unless provided with a flavine supplement. When grown in the absence of a flavine supplement the activities of some of the nitrate-induced enzymes are subnormal. 9. The growth and enzyme characteristics of a total of 123 mutants involving nine different genes indicate that nitrate is reduced to ammonium. Only two possible structural genes for enzymes concerned with nitrate utilization are known. This suggests that only two enzymes, one for the reduction of nitrate to nitrite, the other for the reduction of nitrite to ammonium, are involved in this pathway. PMID:4382427

Pateman, J. A.; Rever, B. M.; Cove, D. J.

1967-01-01

460

Full-mouth oral rehabilitation in a titanium allergy patient using zirconium oxide dental implants and zirconium oxide restorations. A case report from an ongoing clinical study.  

PubMed

This case report describes the full-mouth oral rehabilitation of a titanium allergic patient. The patient was a young female with amelogenesis imperfecta who had generalized massive tooth destruction. All teeth in the mouth were extracted and 15 CeraRoot acid-etched (ICE surface) implants were placed (seven implants in the maxilla and eight implants in the mandible). No immediate temporaries were placed. Temporaries were placed 3 months after surgery, and left in function for 2 months. The case was finally restored with zirconium oxide bridges and ceramic veneering (three bridges in the maxilla and another three in the mandible). The 3-year follow-up showed good stability of soft tissues and bone level. Zirconium oxide implants and restorations might be an alternative for the oral rehabilitation of titanium allergic patients. PMID:20589262

Oliva, Xavi; Oliva, Josep; Oliva, Josep D

2010-01-01

461

Waste Isolation Pilot Plant Nitrate Salt Bearing Waste Container  

E-print Network

Waste Isolation Pilot Plant Nitrate Salt Bearing Waste Container Isolation Plan Prepared of Energy (DOE) and Nuclear Waste Partnership LLC (NWP), collectively referred to as the Permittees. The Order, at paragraph 22, requires the Permittees to submit a WIPP Nitrate Salt Bearing Waste Container

Napp, Nils

462

THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514)  

EPA Science Inventory

The mass transfer rate of pure ammonium nitrate between the aerosol and gas phases was quantified experimentally by the use of the tandem differential mobility analyzer/scanning mobility particle sizer (TDMA/SMPS) technique. Ammonium nitrate particles 80-220 nm in diameter...

463

Inflammatory cytokines induce protein tyrosine nitration in rat astrocytes  

Microsoft Academic Search

Protein tyrosine nitration may be relevant for the pathogenesis of hepatic encephalopathy (HE). Infections, sepsis, and trauma precipitate HE episodes. Recently, serum levels of tumor necrosis factor (TNF)-? were shown to correlate with severity of HE in chronic liver failure. Here the effects of inflammatory cytokines on protein tyrosine nitration in cultured rat astrocytes and rat brain in vivo were

Boris Görg; Hans J. Bidmon; Verena Keitel; Natalie Foster; Roland Goerlich; Freimut Schliess; Dieter Häussinger

2006-01-01

464

Nitrate induced iron deficiency chlorosis in Juncus acutiflorus  

Microsoft Academic Search

Chlorosis caused by iron deficiency is commonly associated with high bicarbonate levels in the soil. However, in rare cases such chlorosis has been observed in soils with high nitrate levels. In a dutch rich-fen, chlorosis has been noted in stands of Juncus acutiflorus at locations where groundwater containing high levels of nitrate reached the surface. Experiments revealed that the chlorosis

A. J. P. Smolders; R. J. J. Hendriks; H. M. Campschreur; J. G. M. Roelofs

1997-01-01

465

Nitrate Water Activities, Science Study Aid No. 4.  

ERIC Educational Resources Information Center

Intended to supplement a regular program, this pamphlet provides background information, related activities, and suggestions for other activities on the subject of nitrate as a water pollutant. Two activities related to plant nutrient pollution, nitrate filtration and measuring mitrate used by plants, are explained in detail, outlining objectives,…

Agricultural Research Service (USDA), Washington, DC.

466

VOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for  

E-print Network

of intensive current research. The effects of multicontaminant exposure on humans are uncertain, and additionalVOCs, Pesticides, Nitrate, and Their Mixtures in Groundwater Used for Drinking Water in the United areas. For each sample, as many as 60 volatile organic compounds (VOCs), 83 pesticides, and nitrate were

467

Modeling of nitrate and bromate in a seawater aquarium  

Microsoft Academic Search

Closed marine systems where there is no significant primary productivity and water changes are impractical exhibit increasing nitrate concentrations over time. At The Living Seas artificial seawater aquarium, nitrate concentration reached 9700?M after 5yr of operation. Concern about potential toxic effects associated with a further increase led to the development of a batch denitrification system, separate from the Main Tank

Gordan Grguric; Christopher J. Coston

1998-01-01

468

Nitrate-Cancrinite Precipitation on Quartz Sand in Simulated Hanford  

E-print Network

Nitrate-Cancrinite Precipitation on Quartz Sand in Simulated Hanford Tank Solutions B A R R Y R . B minerals at the U.S. Department of Energy's Hanford site in Washington. Nitrate-cancrinite began's (DOE) Hanford Site in southeast Washington since the late 1950s (1). To predict the fate

Illinois at Chicago, University of

469

Evaporation of Ammonium Nitrate Aerosol in a Heated Nephelometer  

E-print Network

Evaporation of Ammonium Nitrate Aerosol in a Heated Nephelometer: Implications for Field scattering coefficient of ammonium nitrate aerosol due to evaporation in a heated nephelometer. Changes in the aerosol scattering coefficient due to evaporation agree with measurements to within 10%. Application

470

WESTERN ENERGY SULFATE/NITRATE MONITORING NETWORK, PROGRESS REPORT  

EPA Science Inventory

Interest in sulfate and nitrate aerosols has been on the increase largely due to studies relating sulfate and nitrate to health effects and visibility degradation and to changes in our national energy policy. The present and planned utilization of coal resources in the western Un...

471

FORMATION AND FATE OF ATMOSPHERIC NITRATES: WORKSHOP PROCEEDINGS  

EPA Science Inventory

Articles based on formal presentations given October 22-23, 1979, at the 'Workshop on the Formation and Fate of Atmospheric Nitrates' are documented in the report. The authors discuss nitrate formation from both theoretical (gas and aerosol formation models) and applied (smog cha...

472

[Nitrate accumulating capability of some market garden vegetables].  

PubMed

Nitrate accumulation in plant is essentially function of the amount of nitrate nitrogen present in the substrate. That can be provided by mineral fertilizers or by organic manure. Due to the amount of nitrogen fertilizers needed in order to obtain sufficient yields the presence of nitrate is a general phenomenon in vegetable. Nevertheless the distribution of nitrate ions in the different parts of the plant influences the importance of the accumulation in the different kinds of vegetable. The experiments reported showed that leaves contain more nitrate ions than roots and roots more than fruit. The results obtained in soilless culture on lettuces, tomatoes and egg-plant demonstrated that the amount of accumulated nitrate is also dependent on the equilibrium between the different ions in the nutrient solution. Ammonium, potassium, sulfate and molybdenum have been shown to influence the rate of nitrate accumulation in the different species. It appears that it is not possible to obtain vegetable without nitrate, but it is possible, by an equilibrated fertilization, to reduce the amount accumulated in the tissue. PMID:1030210

Blanc, D

1976-01-01

473

Nitrate sorption and desorption in biochars from fast pyrolysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Increasing the nitrate (NO3-) sorption capacity of Midwestern US soils has the potential to reduce nitrate leaching to ground water and reduce the extent of the hypoxia zone in the Gulf of Mexico. The objective of this study was to determine the sorption and desorption capacity of non-activated and ...

474

Cu(II) - Catalyzed Hydrazine Reduction of Ferrous Nitrate  

SciTech Connect

This report discusses the results of a study of catalyzed hydrazine reduction of ferrous nitrate. It is apparent that there is a substantial reaction between hydrazine and nitrate ion (or nitric acid) to produce HN3 during both the reduction of Fe(III) and during storage at room temperature.

Karraker, D.G.

2001-10-15

475

NITRATE REMOVAL FROM WATER SUPPLIES BY ION EXCHANGE  

EPA Science Inventory

Anion exchange using synthetic organic resins is a proven and practical technology for the removal of nitrate from water supplies. However, disposal of the spent regenerant brine solution containing nitrate is a potential problem. Two processes were examined in detail in this rep...

476

NITRATE REMOVAL FROM WATER SUPPLIES BY ION EXCHANGE - EXECUTIVE SUMMARY  

EPA Science Inventory

Anion exchange using synthetic organic resins is a proven and practical technology for the removal of nitrate from water supplies. However, disposal of the spent regenerant brime solution containing nitrate is a potential problem. Two processes were examined in detail in this rep...

477

Method for improved decomposition of metal nitrate solutions  

DOEpatents

A method for co-conversion of aqueous solutions of one or more heavy metal nitrates is described, wherein thermal decomposition within a temperature range of about 300 to 800/sup 0/C is carried out in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal.

Haas, P.A.; Stines, W.B.

1981-01-21

478

Method for improved decomposition of metal nitrate solutions  

DOEpatents

A method for co-conversion of aqueous solutions of one or more heavy metal nitrates wherein thermal decomposition within a temperature range of about 300.degree. to 800.degree. C. is carried out in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal.

Haas, Paul A. (Knoxville, TN); Stines, William B. (Knoxville, TN)

1983-10-11

479

Phytoremediation of Nitrate-Contaminated Groundwater by Desert Phreatophytes  

Microsoft Academic Search

Two native halophytic shrubs were evaluated for phytoremediation of a nitrate- contaminated aquifer at a former uranium mill site. The shrubs, Sarcobatus vermiculatus and Atriplex canescens, obligate and facultative phreatophytes, respectively, dominate the desert plant community. Stable isotope signatures suggested that both species are rooted into the nitrate plume, a depth averaging more than 10 meters. Aerial photography and ground

Casey McKeon; Edward P. Glenn; David Moore; W. Jody Waugh

480

USING THE BERTHELOT METHOD FOR NITRITE AND NITRATE ANALYSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The indophenol-blue or Berthelot method for ammonium analysis can be used indirectly for the determination of nitrite and nitrate after initial reduction of these species with Devarda’s alloy. Since this approach subjects nitrate determination to interferences normally associated with ammonium anal...

481

Benefits of Safer Drinking Water: The Value of Nitrate Reduction  

Microsoft Academic Search

Nitrates in drinking water, which may come from nitrogen fertilizers applied to crops, are a potential health risk. This report evaluates the potential benefits of reducing human exposure to nitrates in the drinking water supply. In a survey, respondents were asked a series of questions about their willingness to pay for a hypothetical water filter, which would reduce their risk

Stephen R. Crutchfield; Joseph C. Cooper; Daniel Hellerstein

1997-01-01

482

Is the measurement of the isotopic composition of nitrate a good tool for tracing sources of nitrate in groundwater?  

NASA Astrophysics Data System (ADS)

Isotopic biogeochemistry allows tracing of nitrogen sources in the environment. The dual approach i.e 15N and 18O approach has been used for decades to determine the origin of nitrate in surface and groundwater. The isotopic composition of fertilizers differs for example significantly from that of nitrate in atmospheric deposition and nitrate produced by nitrification. A long term study (30 years) based on the use of lysimeters and 15N labelled nitrate showed that nitrate which is not immediately taken up by plants is assimilated into the organic matter pool. This pool produces nitrate, with an isotopic signature of 'newly produced nitrate' and different from its origin (1). Based on this study, the natural stable isotopic composition of nitrate (?18O-NO3-and?15N-NO3-)was measured in water samples collected below the root zone or in aquifers from the Seine River basin. We compared these with the isotopic composition of nitrate from synthetic fertilizers and atmospheric deposition which represent the most significant sources of nitrogen in these systems. In addition, the ?15N of the organic matter pool in cultivated soils from this area was analyzed. The ?18O-NO3-results show clearly that nitrate issued from highly fertilized agricultural soils are freshly produced through nitrification of reduced nitrogen in the soil, instead of being directly transferred through the soil profile from applied fertilizers, indicating the major role of the soil organic matter pool. Our results thus bring new insights in the understanding of nitrogen contamination of surface and groundwater from agricultural watersheds, emphasizing the role of soil organic matter as a buffer. (1). Sebilo M., Nicolardot B., Mayer B., Pinay G. & Mariotti A. (2013). Long-term fate of nitrate fertilizer in agricultural soils. PNAS. 110 (45) : 18185-18189. doi/10.1073/pnas.1305372110.

Sebilo, Mathieu

2014-05-01

483

40 CFR 415.530 - Applicability; description of the silver nitrate production subcategory.  

Code of Federal Regulations, 2011 CFR

...true Applicability; description of the silver nitrate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Silver Nitrate Production Subcategory § 415.530 Applicability; description of the silver nitrate production subcategory....

2011-07-01

484

40 CFR 415.530 - Applicability; description of the silver nitrate production subcategory.  

Code of Federal Regulations, 2014 CFR

...true Applicability; description of the silver nitrate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Silver Nitrate Production Subcategory § 415.530 Applicability; description of the silver nitrate production subcategory....

2014-07-01

485

40 CFR 415.530 - Applicability; description of the silver nitrate production subcategory.  

Code of Federal Regulations, 2012 CFR

...false Applicability; description of the silver nitrate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Silver Nitrate Production Subcategory § 415.530 Applicability; description of the silver nitrate production subcategory....

2012-07-01

486

40 CFR 415.530 - Applicability; description of the silver nitrate production subcategory.  

Code of Federal Regulations, 2013 CFR

...true Applicability; description of the silver nitrate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Silver Nitrate Production Subcategory § 415.530 Applicability; description of the silver nitrate production subcategory....

2013-07-01

487

46 CFR 153.560 - Special requirements for Alkyl (C7-C9) nitrates.  

Code of Federal Regulations, 2014 CFR

...Special requirements for Alkyl (C7-C9) nitrates. 153.560 Section 153.560 Shipping...Special requirements for Alkyl (C7-C9) nitrates. (a) The carriage temperature of octyl nitrates must be maintained below 100 °C...

2014-10-01

488

46 CFR 153.560 - Special requirements for Alkyl (C7-C9) nitrates.  

Code of Federal Regulations, 2012 CFR

...Special requirements for Alkyl (C7-C9) nitrates. 153.560 Section 153.560 Shipping...Special requirements for Alkyl (C7-C9) nitrates. (a) The carriage temperature of octyl nitrates must be maintained below 100 °C...

2012-10-01

489

Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non-hyperaccumulating ferns  

E-print Network

Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non Arsenic reduced the activity of nitrate and nitrite reductase more in Pteris ensiformis than Pteris March 2009 Accepted 26 March 2009 Keywords: Arsenic Nitrate metabolism Pteris vittata Arsenic

Ma, Lena

490

46 CFR 153.560 - Special requirements for Alkyl (C7-C9) nitrates.  

Code of Federal Regulations, 2011 CFR

...Special requirements for Alkyl (C7-C9) nitrates. 153.560 Section 153.560 Shipping...Special requirements for Alkyl (C7-C9) nitrates. (a) The carriage temperature of octyl nitrates must be maintained below 100 °C...

2011-10-01

491

46 CFR 153.560 - Special requirements for Alkyl (C7-C9) nitrates.  

Code of Federal Regulations, 2013 CFR

...Special requirements for Alkyl (C7-C9) nitrates. 153.560 Section 153.560 Shipping...Special requirements for Alkyl (C7-C9) nitrates. (a) The carriage temperature of octyl nitrates must be maintained below 100 °C...

2013-10-01

492

46 CFR 153.560 - Special requirements for Alkyl (C7-C9) nitrates.  

Code of Federal Regulations, 2010 CFR

...Special requirements for Alkyl (C7-C9) nitrates. 153.560 Section 153.560 Shipping...Special requirements for Alkyl (C7-C9) nitrates. (a) The carriage temperature of octyl nitrates must be maintained below 100 °C...

2010-10-01

493

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The...

2010-07-01

494

77 FR 59377 - Solid Agricultural Grade Ammonium Nitrate from Ukraine: Final Results of the Expedited Second...  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-823-810] Solid Agricultural Grade Ammonium Nitrate from Ukraine: Final Results...on solid agricultural grade ammonium nitrate from Ukraine. The Department...on solid agricultural grade ammonium nitrate from Ukraine, pursuant to...

2012-09-27

495

48. U.S. NITRATE PLANT UNDER CONSTRUCTION, VIEW LOOKING N.E. AT ...  

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

48. U.S. NITRATE PLANT UNDER CONSTRUCTION, VIEW LOOKING N.E. AT THE AMMONIUM NITRATE BUILDING UNDER CONSTRUCTION, AUGUST 24, 1918. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

496

78 FR 35258 - Solid Agricultural Grade Ammonium Nitrate from Ukraine: Continuation of Antidumping Duty Order  

Federal Register 2010, 2011, 2012, 2013, 2014

...A-823-810] Solid Agricultural Grade Ammonium Nitrate from Ukraine: Continuation...on solid agricultural grade ammonium nitrate from Ukraine would likely lead...Order: Solid Agricultural Grade Ammonium Nitrate from Ukraine, 66 FR...

2013-06-12

497

77 FR 21527 - Ammonium Nitrate From Russia: Correction to Notice of Opportunity To Request Administrative Review  

Federal Register 2010, 2011, 2012, 2013, 2014

...Administration [A-821-811] Ammonium Nitrate From Russia: Correction to...orders and inadvertently omitted Ammonium Nitrate from Russia, POR 5/2/2011-3...a correction to include the Ammonium Nitrate from Russia administrative...

2012-04-10

498

40 CFR 418.40 - Applicability; description of the ammonium nitrate subcategory.  

Code of Federal Regulations, 2012 CFR

...Applicability; description of the ammonium nitrate subcategory. 418.40 Section...MANUFACTURING POINT SOURCE CATEGORY Ammonium Nitrate Subcategory § 418.40 Applicability; description of the ammonium nitrate subcategory. The...

2012-07-01

499

[Study of the mechanisms of cytotoxic effect of uranyl nitrate].  

PubMed

The mechanisms of cytotoxic effect of uranyl nitrate were studied. It was shown that uranyl nitrate induced HEp-2 cell death, mainly by necrotic way. In the experiments in vitro, uranyl nitrate caused an appearance of 8-oxoguanine in DNA, indicating the induction of oxidative stress. The experiments with isolated rat liver mitochondria revealed that 1 mM uranyl nitrate decreased the respiration rates of mitochondria in state 3 and DNP-induced respiration. At the same time, uranyl nitrate had no influence on the opening of the mitochondrial permeability transition pore and decreased the rate of formation of H2O2 by mitochondria. Possible molecular mechanisms of uranyl-induced necrosis are discussed. PMID:23136770

Belosludtsev, K N; Garmash, S A; Belosludtseva, N V; Belova, S P; Berezhnov, A V; Gudkov, S V

2012-01-01

500

Dissimilatory nitrate reduction by a strain of Clostridium butyricum isolated from estuarine sediments  

Microsoft Academic Search

Nitrate dissimilation in chemostat grown cultures ofClostridium butyricum SS6 has been investigated. Sucrose limited cultures grown on nitrate produced nitrite as the principal end-product of nitrate reduction whilst under nitrate-limiting conditions ammonia accumulated in the spent media. Nitrate reduction was accompanied by the synthesis of a soluble nitrate reductase (123 nmol·NADH oxidised · min-1 · mg protein-1) and in addition,

S. M. Keith; G. T. MacFarlane; R. A. Herbert

1982-01-01