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Sample records for concentrated cerium nitrate

  1. Preparation of high-purity cerium nitrate

    International Nuclear Information System (INIS)

    Avila, Daniela Moraes; Silva Queiroz, Carlos Alberto da; Santos Mucillo, Eliana Navarro dos

    1995-01-01

    The preparation of high-purity cerium nitrate has been carried out Cerium oxide has been prepared by fractioned precipitation and ionic exchange techniques, using a concentrate with approximately 85% of cerium oxide from NUCLEMON as raw material. Five sequential ion-exchange columns with a retention capacity of 170 g each have been used. The ethylenediamine-tetraacetic acid (EDTA) was used as eluent. The cerium content has been determined by gravimetry and iodometry techniques. The resulting cerium oxide has a purity > 99%. This material was transformed in cerium nitrate to be used as precursor for the preparation of Zirconia-ceria ceramics by the coprecipitation technique. (author)

  2. Preparation of high-purity cerium nitrate; Preparacao de nitrato de cerio de alta pureza

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Daniela Moraes; Silva Queiroz, Carlos Alberto da; Santos Mucillo, Eliana Navarro dos [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1995-12-31

    The preparation of high-purity cerium nitrate has been carried out Cerium oxide has been prepared by fractioned precipitation and ionic exchange techniques, using a concentrate with approximately 85% of cerium oxide from NUCLEMON as raw material. Five sequential ion-exchange columns with a retention capacity of 170 g each have been used. The ethylenediamine-tetraacetic acid (EDTA) was used as eluent. The cerium content has been determined by gravimetry and iodometry techniques. The resulting cerium oxide has a purity > 99%. This material was transformed in cerium nitrate to be used as precursor for the preparation of Zirconia-ceria ceramics by the coprecipitation technique. (author) 2 tabs.

  3. Calcination of the cerium concentrate to be cerium oxide

    International Nuclear Information System (INIS)

    Suyanti; MV Purwani

    2016-01-01

    Calcination of the cerium concentrate to be cerium oxide has done. The cerium concentrate were obtained from the Ce making process wear KBrO_3 and without using KBrO_3. The calcination were done with a variation of time 1, 2, 3 and 4 hours with the temperature variations of 700, 800 and 900°C. The easiest calcination of Ce concentrates to be CeO_2 containing majority of Ce(OH)_4 and contains least impurities as Th(OH)_4, (NH_4)_2Y(NO_3), H_4N_5O_1_2La, H_1_2N_3NdO_1_5 and N_3O_9Sm. On the calcination of Ce concentrates process results without using KBrO_3 1, the calcination temperature 900°C was obtained CeO_2 content of 73.53% for calcination time of 4 hours, has little difference when compared with the predictions and calculation result of complete calcination was equal 73.84%. (author)

  4. Systems of cerium(3) nitrate-dimethyl amine nitrate-water and cerium(3) nitrate-dimethyl amine nitrate-water

    International Nuclear Information System (INIS)

    Mininkov, N.E.; Zhuravlev, E.F.

    1976-01-01

    Solubility of solid phases in the systems cerium(3)nitrate-water-dimethyl amine nitrate and cerium(3)nitrate-water-dimethyl amine nitrate has been st ed by the method of isothermal sections at 25 and 50 deo. C. It has been shown that one anhydrous compound is formed in each system with a ratio of cerium(3) nitrate to amine nitrate 1:5. The compounds formed in the systems have been separated from the corresponding solutions and studied by microcrystalloscopic, X-ray phase, thermal and infrared spectroscopic methods. On the basis of spectroscopic studies the following formula has been assigned to the compound: [(CH 3 ) 2 NH 2 + ] 5 x[Ce(NO 3 ) 8 ]. The thermal analysis of the compound has shown that its melting point is 106 deg C. The solubility isotherms in the system Ce(NO 3 ) 3 -H 2 O-(C 2 H 5 ) 2 NHxHNO 3 consist of three branches which intersect in two eutonic points

  5. Sodium nitrate-cerium nitrate-water ternary system at 25 deg C

    International Nuclear Information System (INIS)

    Fedorenko, T.P.; Onishchenko, M.K.

    1978-01-01

    Solubility isotherm of sodium nitrate-cerium nitrate-water system at 25 deg C consists of three crystallization branches of initial salts and double compound of the composition 2NaNO 3 xCe(NO 3 ) 3 x2H 2 O. Sodium nitrate introduced in the solution strengthens complexing. Physico-chemical characteristics are in a good agreement with solubility curve

  6. Corrosion electrochemical behaviors of silane coating coated magnesium alloy in NaCl solution containing cerium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Luo, F.; Li, Q.; Zhong, X.K.; Gao, H.; Dai, Y.; Chen, F.N. [School of Chemistry and Chemical Engineering, Southwest University Chongqing (China)

    2012-02-15

    Sol-gel coatings cannot provide adequate corrosion protection for metal/alloys in the corrosive environments due to their high crack-forming potential. This paper demonstrates the possibility to employ cerium nitrate as inhibitor to decrease the corrosion development of sol-gel-based silane coating on the magnesium alloy in NaCl solution. Cerium nitrate was added into the NaCl solution where the silane coating coated magnesium alloy was immersed. Scanning electron microscopy (SEM) was used to examine surface morphology of the silane coating coated magnesium alloy immersed in NaCl solutions doped and undoped with cerium nitrate. The corrosion electrochemical behaviors were investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The results showed that the introduction of cerium nitrate into NaCl solution could effectively inhibit the corrosion of the silane coating coated magnesium alloy. Moreover, the influence of concentration of cerium nitrate on the corrosion inhibition and the possible inhibiting mechanism were also discussed in detail. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. The systems cerium(3) (samarium) nitrate-quinoline nitrate-water

    International Nuclear Information System (INIS)

    Khisaeva, D.A.; Zhuravlev, E.F.; Semenova, Eh.B.

    1982-01-01

    Using the method of cross sections at 25 and 50 deg C the solubility in the systems cerium (3) nitrate-quinoline nitrate-water and samarium nitrate-quinoline nitrate-water has been studied. It is established that in the systems during chemical interaction of components congruently melting compounds of the composition: Ce(NO 3 ) 2 x2[C 9 H 7 NxHNO 3 ]x6H 2 O and Sm(NO 3 ) 3 x2[C 9 H 7 NxHNO 3 ]x2H 2 O are formed. New solid phases are separated preparatively and are subjected to chemical, differential thermal and IR spectroscopic analyses. The investigation results are compared with similar ones for nitrates of other representatives of lanthanide group

  8. Thermal decomposition study of uranyl nitrate and cerium hydroxide in a spray dryer

    International Nuclear Information System (INIS)

    Silva Wildhagen, G.R. da.

    1993-05-01

    A study, in a spray dryer system based on drying and thermal decomposition of uranyl nitrate solutions aiming the production of uranium trioxide adequate for the use in posterior steps of reduction and hydro fluorination in nuclear fuel cycle; and cerium hydroxide suspensions for the production of cerium oxide with high surface area is presented. Thus, the project and construction of a countercurrent spray dryer was elaborated for capacity of 10 Kg U O 3 /h and 3,5 k Ce O 2 /h. The methodology used in these experiments consisted in the analysis of several parameters (concentration and flow rate of the feed, atomization pressure and inlet temperature of the dryer) over the physical and chemical properties of the products. Using the obtained results, with the help of a mathematical model, it was developed the project of a continuous pilot unity for the production of uranium trioxide or cerium oxide, with capacity of 20 Kg U O 3 /h or 10 Kg Ce O 2 /h, respectively. (author)

  9. Determination of silver and cerium in the liver and the kidney from a severely burned infant treated with silver sulfadiazine and cerium nitrate

    International Nuclear Information System (INIS)

    Hirakawa, Keiko

    1983-01-01

    Silver and cerium in the liver and the kidney from severely burned infant were analyzed by neutron activation method. The patient was treated topically with cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for 3 months. Then, the treatment with these drugs was stopped because o f abdominal distention. The patient died 1 month after the cessation of the treatment with these drugs. The tissue specimens, blank liver sample and reference standards were irradiated with TRIGA MARK II Reactor of Rikkyo University. About 1 month after the irradiation, the activities were measured with a Ge(Li) detector coupled to a 4096 channel pulse height analyzer. A large amount of silver was detected both in the liver and in the kidney and a trace of cerium only in the liver. A considerable amount of silver was detected in the liver and its quantity was about 1600 times more than that of normal livers reported by Hamilton, Minski and Cleary (1972 -- 73). Neither silver nor cerium were detected in the blank liver. These results suggest that prolonged topical chemotherapy of cerium nitrate/silver sulfadiazine cream and cerium nitrate solution for the extensive burn injuries causes considerable absorption of silver and cerium into the liver and the kidney. (author)

  10. Study of the effect of cerium nitrate on AA2024-T3 by means of electrochemical micro-cell technique

    International Nuclear Information System (INIS)

    Paussa, L.; Andreatta, F.; Rosero Navarro, N.C.; Durán, A.; Fedrizzi, L.

    2012-01-01

    Highlights: ► We evaluate the cerium nitrate effect on the electrochemical behavior of AA2024-T3. ► We examine how AA2024-T3 microstructure affects cerium precipitation mechanism. ► The entire AA2024-T3 surface is involved in cerium precipitation. ► Anodic and cathodic inhibitions are both provided by cerium precipitation. ► Mg-rich intermetallics are preferential sites for cerium precipitation. - Abstract: This work evaluates the effect of cerium nitrate as corrosion inhibitor for AA2024-T3 in the view of its introduction in sol–gel coatings able to provide self-healing ability. Since it is well established that deposition of Ce species is activated by the local pH increase, the objective of this paper is to investigate the behavior of AA2024-T3 (open circuit potential and polarization curves) in the presence of Ce species in aggressive solutions by means of a local technique, the electrochemical micro-cell. This technique enables the investigation of small areas with resolution in the micrometer range by the use of glass capillaries to define the working electrode area. The micro-cell results clearly displayed that the entire AA2024-T3 area exposed to the cerium-containing electrolyte was involved in the cerium precipitation mechanism. The heterogeneous electrochemical behavior of the microstructure is minimized by the formation of a cerium-containing layer able to protect the metal substrate.

  11. Ceria nanoparticles vis-à-vis cerium nitrate as corrosion inhibitors for silica-alumina hybrid sol-gel coating

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, R.V. [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Aruna, S.T., E-mail: staruna194@gmail.com [Surface Engineering Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, HAL Airport Road, Kodihalli, Bengaluru 560017 (India); Sampath, S. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengaluru 560012 (India)

    2017-01-30

    Highlights: • Corrosion protection efficiency comparison of ceria nanoparticles and cerium nitrate. • Silica-alumina hybrid coating exhibited good barrier protection. • Detailed XPS study confirm the hybrid structure and presence of Ce species in coating. • Loss of cerium ions not prevalent in ceria doped coating unlike that of cerium nitrate. • Ceria increased the coating integrity, corrosion inhibition and barrier protection. - Abstract: The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and cerium nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing cerium nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings.

  12. The systems lanthanum (cerium, samarium) nitrate-tetramethyl-ammonium nitrate-water

    International Nuclear Information System (INIS)

    Zhuravlev, E.F.; Khisaeva, D.A.; Semenova, Eh.B.

    1984-01-01

    The method of cross sections at 25 and 50 deg C has been applied to study solubility in the systems lanthanum nitrate-tetramethyl ammonium nitrate-water (1), cesium (3) nitrate-tetramethyl ammonium nitrate-water (2) and samarium nitrate-tetramethyl ammonium nitrate-water (3). Crystallization fields of congruently dissolving compounds with 1:3 ratio of salt components (in system 1) and 1:2 ratio (in systems 2 and 3) are found in the systems. New solid phases are separated preparatively and subjected to chemical, differential thermal and IR spectroscopic analyses. Compositions of formed compounds are compared with the compositions known for nitrates of other representatives of light lanthanides

  13. Nanostructured sol-gel coatings doped with cerium nitrate as pre-treatments for AA2024-T3

    International Nuclear Information System (INIS)

    Zheludkevich, M.L.; Serra, R.; Montemor, M.F.; Yasakau, K.A.; Salvado, I.M. Miranda; Ferreira, M.G.S.

    2005-01-01

    Nanostructured hybrid sol-gel coatings doped with cerium ions were investigated in the present work as pre-treatments for the AA2024-T3 alloy. The sol-gel films have been synthesized from tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors. Additionally the hybrid sol was doped with zirconia nanoparticles prepared from hydrolyzed tetra-n-propoxyzirconium (TPOZ). Cerium nitrate, as corrosion inhibitor, was added into the hybrid matrix or into the oxide nanoparticles. The chemical composition and the structure of the hybrid sol-gel films were studied by XPS (X-ray photoelectron spectroscopy) and AFM (atomic force microscopy), respectively. The evolution of the corrosion protection properties of the sol-gel films was studied by EIS (electrochemical impedance spectroscopy), which can provide quantitative information on the role of the different pre-treatments. Different equivalent circuits, for different stages of the corrosion processes, were used in order to model the coating degradation. The models were supported by SEM (scanning electron microscopy) measurements. The results show that the sol-gel films containing zirconia nanoparticles present improved barrier properties. Doping the hybrid nanostructured sol-gel coatings with cerium nitrate leads to additional improvement of the corrosion protection. The zirconia particles present in the sol-gel matrix seem to act as nanoreservoirs providing a prolonged release of cerium ions. The nanostructured sol-gel films doped with cerium nitrate can be proposed as a potential candidate for substitution of the chromate pre-treatments for AA2024-T3

  14. Effectiveness of Cerium Nitrate-Silver Sulfadiazine in the Treatment of Facial Burns: A Multicenter, Randomized, Controlled Trial

    NARCIS (Netherlands)

    Oen, I.M.M.H.; van Baar, M.E.; Middelkoop, E.; Nieuwenhuis, M.K.

    2012-01-01

    Background: The face is a very frequent site of burn injuries. This multicenter, randomized, controlled trial thus investigates the effectiveness of cerium nitrate-silver sulfadiazine in the treatment of facial burns compared with silver sulfadiazine. Methods: Adult patients with acute facial burns

  15. Procedure for the separation of cerium from crude phosphates and rare earth concentrates

    International Nuclear Information System (INIS)

    Richter, H.; Koenig, O.; Schmitt, A.; Grauss, H.; Freitag, S.

    1986-01-01

    The invention has to do with a procedure for the separation of cerium from crude phosphates and rare earth phosphate concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions. It is aimed at the cerium separation from the raw material at an early stage of reprocessing without preceding elimination of other components and impurities. The rare earth phosphate concentrates or crude phosphates are dissolved in nitric acid, the Ce 3+ is oxidized with potassium permanganate or magnanese(IV) hydroxide, and cerium(IV) phosphate is precipitated as pure substance by decreasing the acidity of the solution

  16. [Nitrate concentrations in tap water in Spain].

    Science.gov (United States)

    Vitoria, Isidro; Maraver, Francisco; Sánchez-Valverde, Félix; Armijo, Francisco

    2015-01-01

    To determine nitrate concentrations in drinking water in a sample of Spanish cities. We used ion chromatography to analyze the nitrate concentrations of public drinking water in 108 Spanish municipalities with more than 50,000 inhabitants (supplying 21,290,707 potential individuals). The samples were collected between January and April 2012. The total number of samples tested was 324. The median nitrate concentration was 3.47 mg/L (range: 0.38-66.76; interquartile range: 4.51). The water from 94% of the municipalities contained less than 15 mg/L. The concentration was higher than 25mg/L in only 3 municipalities and was greater than 50mg/L in one. Nitrate levels in most public drinking water supplies in municipalities inhabited by almost half of the Spanish population are below 15 mg/L. Copyright © 2014 SESPAS. Published by Elsevier Espana. All rights reserved.

  17. Effect of Sol Concentration, Aging and Drying Process on Cerium Stabilization Zirconium Gel Produced by External Gelation

    Science.gov (United States)

    Sukarsono, R.; Rachmawati, M.; Susilowati, S. R.; Husnurrofiq, D.; Nurwidyaningrum, K.; Dewi, A. K.

    2018-02-01

    Cerium Stabilized Zirconium gel has been prepared using external gelation process. As the raw materials was used ZrO(NO3)2 and Ce(NO3)4 nitrate salt which was dissolved with water into Zr-Ce nitrate mixture. The concentration of the nitrate salt mixture in the sol solution was varied by varying the concentration of zirconium and cerium nitrate in the sol solution and the addition of PVA and THFA to produce a sol with a viscosity of 40-60 cP. The viscosity range of 40-60cP is the viscosity of the sol solution that was easy to produce a good gel in the gelation apparatus. Sol solution was casted in a gelation column equipped with following tools: a 1 mm diameter drip nozzle which was vibrated to adjust the best frequency and amplitude of vibration, a flow meter to measure the flow rate of sol, flowing of NH3 gas to presolidification process. Gelation column was contained NH4OH solution as gelation medium and gel container to collect gel product. Gel obtained from the gelation process than processed with ageing, washing, drying and calcinations to get round gel and not broken at calcinations up to 500°C. The parameters observed in this research are variation of Zr nitrate concentration, Ce nitrate concentration, ratio of Zr and Ce in the sol and ageing and drying process method which was appropriate to get a good gel. From the gelation processes that has been done, it can be seen that with the presolidification process can be obtained a round gel and without presolidification process, produce not round gel. In the process of ageing to get not broken gel, ageing was done on the rotary flask so that during the ageing, gels rotate in gelation media. Gels, then be washed by dilute ammonium nitrate, demireralized water and iso prophyl alcohol. The washed gel was then dried by vacuum drying to form pores on the gel which become the path for the gases resulting from decomposition of the gel to exit the gel. Vacuum drying can prevent cracking because the pores allow the gel

  18. Synergism between cerium nitrate and sodium dodecylbenzenesulfonate on corrosion of AA5052 aluminium alloy in 3 wt.% NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Wang, Dapeng; Gao, Lixin; Zhang, Daquan, E-mail: zhdq@sh163.net

    2016-12-15

    Highlights: • Effectively prevent corrosion of AA5052 alloy by using the mixture of cerium nitrate and sodium dodecylbenzenesulfonate. • Synergistic mechanism of the combination of cerium nitrate and sodium dodecylbenzenesulfonate. • Structure of the complex formed between cerium ions and dodecylbenzenesulfonate. • The optimal adsorption model of dodecylbenzenesulfonate on the Al{sub 2}O{sub 3} and CeO{sub 2} surface. - Abstract: The synergistic inhibition effect of rare earth cerium nitrate and sodium dodecylbenzenesulfonate (DBS) on corrosion of AA5052 aluminium alloy in 3 wt.% NaCl solution was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curve, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The results show that the single cerium nitrate or DBS has a limited inhibition effect against corrosion of AA5052 alloy. The combination cerium ions with DBS produced strong synergistic effect on corrosion inhibition for AA5052 alloy and rendered a negaitve shift of the corrosion potential. The formation of the complex of Al(DBS){sub 3} and Ce(DBS){sub 3} stabilized the passive film of Al{sub 2}O{sub 3} and CeO{sub 2}, retarding both the cathodic and anodic processes of AA5052 alloy corrosion reaction significantly.

  19. Two-phase titration of cerium(3) by permanganate

    International Nuclear Information System (INIS)

    Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

    1986-01-01

    Reaction of cerium (3) and permanganate was investigated at a room temperature depending on PH, concentrations of pyrophosphate, cerium (3), tetraphenylphosphonium and foreign compounds. Selective method of two-phase titration determination of cerium (3) by permanganate without using silver compounds, preliminary separation of chlorides, nitrates, was developed. The method was tested using alloys based on iron, nickel, REE, copper, cobalt (S r ≤0.008). Correctness is proved with method of standard additives

  20. The kinetics of the cerium(IV)-uranium(IV) reaction at low sulfate concentrations

    International Nuclear Information System (INIS)

    Michaille, P.; Kikindai, T.

    1977-01-01

    The rate of oxidation of uranium(IV) by cerium(IV) was measured with a stopped-flow spectrophotometer at sulfuric acid concentrations of 2 x 10 -6 to 0.5 M. At a constant hydrogen ion concentration of 0.5 M, the maximum rate constant was observed for 2 x 10 -3 M sulfuric acid; at that concentration, two sulfate ions were involved in the activated complex. The dependence of the rate constant on the hydrogen ion concentration showed that the reaction paths involving one or two sulfate ions also involved one hydroxyl ion, whereas one hydrogen ion was involved in the five sulfate dependent path. Spectrophotometric measurements supported the existence of a hydrolyzed monosulfatocomplex of cerium(IV). (author)

  1. Efficiency of nitrate uptake in spinach : impact of external nitrate concentration and relative growth rate on nitrate influx and efflux

    NARCIS (Netherlands)

    Ter Steege, MW; Stulen, [No Value; Wiersema, PK; Posthumus, F; Vaalburg, W

    1999-01-01

    Regulation of nitrate influx and efflux in spinach (Spinacia oleracea L., cv. Subito), was studied in short-term label experiments with N-13- and N-15-nitrate. Nitrate fluxes were examined in relation to the N demand for growth, defined as relative growth rate (RGR) times plant N concentration.

  2. Concentration of Nitrate in Bottled Drinking Water in Qom, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Saberi Bidgoli

    2013-11-01

    Full Text Available Background & Aims of the Study: The global consumption of bottled water is growing with substantial growth in sales volumes on every continent. The highest growth rates are occurring in Asia and South America. Biological and chemical monitoring of these waters is necessary. The aim of current study was determination of nitrate concentration in bottled drinking water in Qom, Iran in 2012. Materials & Methods: A cross-sectional study carried out in Qom, Iran. First of all, 18 most frequent brands of bottled drinking waters were purchased in June 2012 randomly. Then concentration of nitrate was measured according to the spectrophotometric method. In next step, experiment data were analyzed by Excel Software and P value was obtained by statistical calculations. Finally data were comprised with written nitrate concentration on labels and recommended permissible values . Results: The median nitrate concentration was 2.1 mg/L with the minimum 0.8 mg/L and maximum 8.1 mg/L. In 66.7 % of the samples, the measured nitrate concentrations were less than the written nitrate concentrations and in 33.3% of samples, the nitrate concentration was higher. The statistical calculation proved the significant difference between the median of written nitrate concentration on the label and investigated nitrate concentration (P value > 0.05. Conclusions: It be concluded that the measured nitrate concentration in all of the water samples is below the recommended permissible level.

  3. The influence of nitrate concentrations and acidity on the electrocatalytic reduction of nitrate on platinum

    NARCIS (Netherlands)

    Groot, de M.T.; Koper, M.T.M.

    2004-01-01

    A study was performed to determine the influence of nitrate concentration and acidity on the reaction rate and selectivity of the electrocatalytic nitrate reduction on platinum. There are two different nitrate reduction mechanisms on platinum: a direct mechanism (0.4–0.1 V vs. SHE) and an indirect

  4. Electrochemical techniques for practical evaluation of corrosion inhibitor effectiveness. Performance of cerium nitrate as corrosion inhibitor for AA2024T3 alloy

    International Nuclear Information System (INIS)

    Rosero-Navarro, N.C.; Curioni, M.; Bingham, R.; Duran, A.; Aparicio, M.; Cottis, R.A.; Thompson, G.E.

    2010-01-01

    In this work, a split-cell technique and image-assisted electrochemical noise analysis, which provide minimal perturbation of the freely corroding system and good time resolution, are proposed as a tool for simultaneous investigation of the corrosion inhibition mechanism and assessment of performance. The results obtained are compared with results from traditional electrochemical impedance spectroscopy, disclosing the advantages of these techniques in the evaluation of inhibitor performance. Specific attention is also given to the investigation of corrosion inhibition by cerium nitrate.

  5. Nitrate concentrations in drainage water in marine clay areas : exploratory research of the causes of increased nitrate concentrations

    NARCIS (Netherlands)

    Boekel, van E.M.P.M.; Roelsma, J.; Massop, H.T.L.; Hendriks, R.F.A.; Goedhart, P.W.; Jansen, P.C.

    2013-01-01

    The nitrate concentrations measured in drainage water and groundwater at LMM farms (farms participating in the National Manure Policy Effects Measurement Network (LLM)) in marine clay areas have decreased with 50% since the mid-nineties. The nitrate concentrations in marine clay areas are on average

  6. Electron transfer reactions of 1-phenyl-4-vinylpyrazole mediated by cerium(IV) ammonium nitrate

    International Nuclear Information System (INIS)

    Pitarch-Vinuesa, M.; Miranda, M.A.; Medio-Simon, M.; Sepulveda-Arques, J.

    1993-01-01

    The title compound is converted into the cyclic ethers 5 and the alcohol 6 upon treatment with ceric ammonium nitrate in acetone. Using methanol as a solvent the dimethoxy derivative 9 and the nitrate ester 10 are formed. No cross cycloaddition is observed in the presence of olefins such as ethyl vinyl ether, DMAD, or indene; however, with cyclopentadiene as co-reagent a mixture of the exo-endo Diels-Alder adducts 14 involving the vinylic system of 1 as 2π component is obtained. The results are rationalized through the intermediacy of the radical cation 1 .+ , generated by single electron transfer (SET) from the neutral precursor 1 to Ce(IV)

  7. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate

    International Nuclear Information System (INIS)

    Vasconcelos, Mari Estela de

    2006-01-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  8. Densities concentrations of aqueous of uranyl nitrate solutions

    International Nuclear Information System (INIS)

    Rodrigo Otero, A.; Rodriguez Hernandez, B.; Fernandez Rodriguez, L.

    1966-01-01

    The ratio density-concentration of aqueous uranyl nitrate solutions expressed as U 3 O 8 grams/liter, U grams/liter and hexahydrate uranyl nitrate weight percent at different temperatures, are established. Experimental values are graphically correlated and compared whit some published data. (Author) 2 refs

  9. Thermal denitration of high concentration nitrate salts waste water

    International Nuclear Information System (INIS)

    Hwang, D. S.; Oh, J. H.; Choi, Y. D.; Hwang, S. T.; Park, J. H.; Latge, C.

    2003-01-01

    This study investigated the thermodynamic and the thermal decomposition properties of high concentration nitrate salts waste water for the lagoon sludge treatment. The thermodynamic property was carried out by COACH and GEMINI II based on the composition of nitrate salts waste water. The thermal decomposition property was carried out by TG-DTA and XRD. Ammonium nitrate and sodium nitrate were decomposed at 250 .deg. C and 730 . deg. C, respectively. Sodium nitrate could be decomposed at 450 .deg. C in the case of adding alumina for converting unstable Na 2 O into stable Na 2 O.Al 2 O 3 . The flow sheet for nitrate salts waste water treatment was proposed based on the these properties data. These will be used by the basic data of the process simulation

  10. Modeling groundwater nitrate concentrations in private wells in Iowa.

    Science.gov (United States)

    Wheeler, David C; Nolan, Bernard T; Flory, Abigail R; DellaValle, Curt T; Ward, Mary H

    2015-12-01

    Contamination of drinking water by nitrate is a growing problem in many agricultural areas of the country. Ingested nitrate can lead to the endogenous formation of N-nitroso compounds, potent carcinogens. We developed a predictive model for nitrate concentrations in private wells in Iowa. Using 34,084 measurements of nitrate in private wells, we trained and tested random forest models to predict log nitrate levels by systematically assessing the predictive performance of 179 variables in 36 thematic groups (well depth, distance to sinkholes, location, land use, soil characteristics, nitrogen inputs, meteorology, and other factors). The final model contained 66 variables in 17 groups. Some of the most important variables were well depth, slope length within 1 km of the well, year of sample, and distance to nearest animal feeding operation. The correlation between observed and estimated nitrate concentrations was excellent in the training set (r-square=0.77) and was acceptable in the testing set (r-square=0.38). The random forest model had substantially better predictive performance than a traditional linear regression model or a regression tree. Our model will be used to investigate the association between nitrate levels in drinking water and cancer risk in the Iowa participants of the Agricultural Health Study cohort. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Modeling groundwater nitrate concentrations in private wells in Iowa

    Science.gov (United States)

    Wheeler, David C.; Nolan, Bernard T.; Flory, Abigail R.; DellaValle, Curt T.; Ward, Mary H.

    2015-01-01

    Contamination of drinking water by nitrate is a growing problem in many agricultural areas of the country. Ingested nitrate can lead to the endogenous formation of N-nitroso compounds, potent carcinogens. We developed a predictive model for nitrate concentrations in private wells in Iowa. Using 34,084 measurements of nitrate in private wells, we trained and tested random forest models to predict log nitrate levels by systematically assessing the predictive performance of 179 variables in 36 thematic groups (well depth, distance to sinkholes, location, land use, soil characteristics, nitrogen inputs, meteorology, and other factors). The final model contained 66 variables in 17 groups. Some of the most important variables were well depth, slope length within 1 km of the well, year of sample, and distance to nearest animal feeding operation. The correlation between observed and estimated nitrate concentrations was excellent in the training set (r-square = 0.77) and was acceptable in the testing set (r-square = 0.38). The random forest model had substantially better predictive performance than a traditional linear regression model or a regression tree. Our model will be used to investigate the association between nitrate levels in drinking water and cancer risk in the Iowa participants of the Agricultural Health Study cohort.

  12. Nitrate concentrations in soil solutions below Danish forests

    DEFF Research Database (Denmark)

    Callesen, Ingeborg; Raulund-Rasmussen, Karsten; Gundersen, Per

    1999-01-01

    leaching in relation to land-use, a national monitoring programme has established sampling routines in a 7x7 km grid including 111 points in forests. During winters of 1986-1993, soil samples were obtained from a depth of 0-25, 25-50, 50-75 and 75-100 cm. Nitrate concentrations in soil solutions were...... species. A few sites deviated radically from the general pattern of low concentrations. The elevated concentrations recorded there were probably caused by high levels of N deposition due to emission from local sources or temporal disruptions of the N cycle. The nitrate concentration in the soil solution...

  13. Cerium concentrate and mixed rare earth chloride by the oxidative decomposition of bastnaesite in molten sodium hydroxide

    International Nuclear Information System (INIS)

    Iijima, Toshio; Kato, Kazuhiro; Kuno, Toyohiko; Okuwaki, Akitsugu; Umetsu, Yoshiaki; Okabe, Taijiro

    1993-01-01

    Bastnaesite was treated in molten NaOH at 623-777 K for 10-60 min under atmosphere. Cerium-(III) in the ore was easily oxidized 95% or more within 30 min to give an oxidation product composed of solid solutions of CeO 2 -rich and CeO 2 -lean phases and Ce-free rare earth oxide phase. Simultaneously fluoride ion was removed 97% or more. Cerium concentrate was prepared from the oxidation product by leaching with 0.1-3 M HCl solution. The yield of cerium concentrate and the CeO 2 content reached 55-57% and 70-72%, respectively. Mixed rare earth chloride is composed of about 90% rare earth chloride and 10% alkaline earth chloride, and the contents of CeCl 3 , LaCl 3 , NdCl 3 , and PrCl 3 are 11.5, 58.5, 14.4, and 5.4%, respectively. The particle size of resulting cerium concentrate was fairly uniform and about 0.1 μm

  14. Characterization of microstructure and catalytic of cerium oxide obtained by colloidal solution

    International Nuclear Information System (INIS)

    Senisse, C.A.L.; Bergmann, C.P.; Alves, A.K.

    2012-01-01

    This study investigated to obtain particles of cerium oxide, for use as catalysts for the combustion of methane using the technique of through polymeric colloidal solution. Obtaining the colloidal system is based on hydrolysis of salts such as cerium acetylacetonate, cerium nitrate in the presence of additives such as polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA), at concentrations of 5, 10 and 15% in aqueous or alcoholic medium. These solutions containing ions of interest were subjected to a heat treatment at 650° C for 30 minutes, with heating rate of 2 ° C/ min. After heat treatment, the fibers were characterized according to their morphology, surface area, crystallinity, weight loss and catalytic activity. Samples obtained from cerium acetylacetonate were more reactive than the cerium nitrate to the combustion of methane, as showed greater conversions and higher temperatures reached during the process, which is of utmost importance since the combustion catalytic methane is used for generating thermal energy. After the reaction with methane, the samples underwent significant change in surface area, probably due to the intensity of combustion reactions of the nitrate and the generation of heat involved in this reaction, which gave rise to coarse particles. During the combustion process using the obtained from particles of cerium acetylacetonate, there was the release of large quantities of nitrogen compared to the results of assays with the particles obtained with cerium nitrate. (author)

  15. Cerium enhances germination and shoot growth, and alters mineral nutrient concentration in rice

    Science.gov (United States)

    García-Morales, Soledad; Pérez-Sato, Juan Antonio

    2018-01-01

    Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth. PMID:29579100

  16. Effect of nitrogen concentration of urea ammonium nitrate, and ...

    African Journals Online (AJOL)

    Liquid urea ammonium nitrate (UAN) was applied to dryland Pennisetum clandestinum (Kikuyu (Chiov)) and Cynodon hybrid (Coastcross II (L.) (Pers.)) pastures at two levels (207 and 414 kg N/ha/season) and at three concentrations (10, 5; 21 and 42% N) of nitrogen. The degree of leaf scorch increased as both the amount ...

  17. Determination of cerium

    International Nuclear Information System (INIS)

    Stepin, V.V.; Kurbatova, V.I.; Fedorova, N.D.

    1980-01-01

    Techniques of cerium determination in steels and alloys are developed. Amperometric method of determination which is based on Ce(4) titration by a solution of double salt of sulfuric Fe(2) and ammonium when cerium amount exceeds 0.01% is suggested. Cerium is oxidated to tetravalent state by KMnO 4 . The elements interfering with the determination (Cr, Ni etc.) are separated by means of deposition. When cerium content exceeds 0.005% in steels and alloys the determination is carried out using photometric method with arsenazo 3 in hydrochloric medium (pH 1.8-2.3). Optimum concentration is 5-50 μg [ru

  18. Study on recovering directly the commercial cerium oxide and total of residue rare earths from Dongpao bastnasite concentrate

    International Nuclear Information System (INIS)

    Nguyen Trong Hung; Nguyen Thanh Chung; Luu Xuan Dinh

    2003-01-01

    A technology for decomposition roasting and sequential leaching processes of Dong Pao bastnasite concentrate to recover directly commercial cerium oxide and total of residue rare earth elements from the leaching solution of the roasted product have been investigated. The bastnasite concentrate is initially roasted at temperature range of 600 - 650 degC and for time of 4 hrs in order to decompose and convert the hardly soluble carbonate forms of ore into easily soluble oxide. The roasted solid is then leached with sulfuric acid solution of 6N at 60 degC for 4 hrs to convert rare earths in oxide and fluoride form into rare earth sulfate. The recovery yield of rare earths of these stages is more than 95%. The attention has especially been paid on recovering directly the commercial cerium oxide and total of residue rare earth element from the above leaching solution. Complex ions of CeSO 4 2+ , Ce(SO 4 ) 2 , Ce(SO 4 ) 3 2- and Ce(SO 4 ) 4 4- exist in aqueous solution of cerium (IV) sulfate. Based on the property, the method of ion - sieve with DOWEX cation resin column has been applied to estimating separation of the ceric complex anions from Ln(III). The survey showed that most of the ceric complex anions are separated from total of residue rare earths. The latter which are absorbed in the cation column are recovered by elution of HCl of 4N. The recovery yield of cerium can only be reached 20% but the purity of that is very high, can be reached 99.6%. About 5 kg of CeO 2 of high grade and 5 kg of TREO of commercial specification have been produced. (author)

  19. High concentrations of cadmium, cerium and lanthanum in indoor air due to environmental tobacco smoke

    International Nuclear Information System (INIS)

    Böhlandt, Antje; Schierl, Rudolf; Diemer, Juergen; Koch, Christoph; Bolte, Gabriele; Kiranoglu, Mandy; Fromme, Hermann; Nowak, Dennis

    2012-01-01

    Background: Environmental tobacco smoke (ETS) is one of the most important sources for indoor air pollution and a substantial threat to human health, but data on the concentrations of the trace metals cerium (Ce) and lanthanum (La) in context with ETS exposure are scarce. Therefore the aim of our study was to quantify Ce and La concentrations in indoor air with high ETS load. Methods: In two subsequent investigations Ce, La and cadmium (Cd) in 3 smokers' (11 samples) and 7 non-smokers' (28 samples) households as well as in 28 hospitality venues in Southern Germany were analysed. Active sampling of indoor air was conducted continuously for seven days in every season in the smokers' and non-smokers' residences, and for 4 h during the main visiting hours in the hospitality venues (restaurants, pubs, and discotheques). Results: In terms of residences median levels of Cd were 0.1 ng/m 3 for non-smokers' and 0.8 ng/m 3 for smokers' households. Median concentrations of Ce were 0.4 ng/m 3 and 9.6 ng/m 3 , and median concentrations of La were 0.2 ng/m 3 and 5.9 ng/m 3 for non-smokers' and for smokers' households, respectively. In the different types of hospitality venues median levels ranged from 2.6 to 9.7 ng/m 3 for Cd, from 18.5 to 50.0 ng/m 3 for Ce and from 10.6 to 23.0 ng/m 3 for La with highest median levels in discotheques. Conclusions: The high concentrations of Ce and La found in ETS enriched indoor air of smokers' households and hospitality venues are an important finding as Ce and La are associated with adverse health effects and data on this issue are scarce. Further research on their toxicological, human and public health consequences is urgently required. - Highlights: ► We quantified cer, lanthanum and cadmium concentrations in indoor air. ► Cer and lanthanum concentrations were high in tobacco smoke enriched locations. ► Both elements can be considered as good markers for indoor air quality.

  20. Production of cerium dioxide microspheres by an internal gelation sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Katalenich, Jeffrey A.

    2017-03-27

    An internal gelation sol-gel technique was used to prepare cerium dioxide microspheres with uniform diameters near 100 µm. In this process, chilled aqueous solutions containing cerium, hexamethylenetetramine (HMTA), and urea are transformed into a solid gel by heat addition and are subsequently washed, dried, and sintered to produce pure cerium dioxide. Cerous nitrate and ceric ammonium nitrate solutions were compared for their usefulness in microsphere production. Gelation experiments were performed with both cerous nitrate and ceric ammonium nitrate to determine desirable concentrations of cerium, HMTA, and urea in feed solutions as well as the necessary quantity of ammonium hydroxide added to cerium solutions. Analysis of the pH before and after sample gelation was found to provide a quantitative metric for optimal parameter selection along with subjective evaluations of gel qualities. The time necessary for chilled solutions to gel upon inserting into a hot water bath was determined for samples with a variety of parameters and also used to determine desirable formulations for microsphere production. A technique for choosing the optimal mixture of ceric ammonium nitrate, HMTA, and urea was determined using gelation experiments and used to produce microspheres by dispersion of the feed solution into heated silicone oil. Gelled spheres were washed to remove excess reactants and reaction products before being dried and sintered. X-ray diffraction of air-dried microspheres, sintered microspheres, and commercial CeO2 powders indicated that air-dried and sintered spheres were pure CeO2.

  1. Nitrate-Rich Vegetables Increase Plasma Nitrate and Nitrite Concentrations and Lower Blood Pressure in Healthy Adults.

    Science.gov (United States)

    Jonvik, Kristin L; Nyakayiru, Jean; Pinckaers, Philippe Jm; Senden, Joan Mg; van Loon, Luc Jc; Verdijk, Lex B

    2016-05-01

    Dietary nitrate is receiving increased attention due to its reported ergogenic and cardioprotective properties. The extent to which ingestion of various nitrate-rich vegetables increases postprandial plasma nitrate and nitrite concentrations and lowers blood pressure is currently unknown. We aimed to assess the impact of ingesting different nitrate-rich vegetables on subsequent plasma nitrate and nitrite concentrations and resting blood pressure in healthy normotensive individuals. With the use of a semirandomized crossover design, 11 men and 7 women [mean ± SEM age: 28 ± 1 y; mean ± SEM body mass index (BMI, in kg/m(2)): 23 ± 1; exercise: 1-10 h/wk] ingested 4 different beverages, each containing 800 mg (∼12.9 mmol) nitrate: sodium nitrate (NaNO3), concentrated beetroot juice, a rocket salad beverage, and a spinach beverage. Plasma nitrate and nitrite concentrations and blood pressure were determined before and up to 300 min after beverage ingestion. Data were analyzed using repeated-measures ANOVA. Plasma nitrate and nitrite concentrations increased after ingestion of all 4 beverages (P nitrate concentrations were similar for all treatments (all values presented as means ± SEMs: NaNO3: 583 ± 29 μmol/L; beetroot juice: 597 ± 23 μmol/L; rocket salad beverage: 584 ± 24 μmol/L; spinach beverage: 584 ± 23 μmol/L). Peak plasma nitrite concentrations were different between treatments (NaNO3: 580 ± 58 nmol/L; beetroot juice: 557 ± 57 nmol/L; rocket salad beverage: 643 ± 63 nmol/L; spinach beverage: 980 ± 160 nmol/L; P = 0.016). When compared with baseline, systolic blood pressure declined 150 min after ingestion of beetroot juice (from 118 ± 2 to 113 ± 2 mm Hg; P nitrate-rich beetroot juice, rocket salad beverage, and spinach beverage effectively increases plasma nitrate and nitrite concentrations and lowers blood pressure to a greater extent than sodium nitrate. These findings show that nitrate-rich vegetables can be used as dietary nitrate

  2. The Effect of Nitrate Levels and Harvest Times on Fe, Zn, Cu, and K, Concentrations and Nitrate Reductase Activity in Lettuce and Spinach

    OpenAIRE

    Z. Gheshlaghi; R. Khorassani; G.H. Haghnia; M. Kafi

    2015-01-01

    Leafy vegetables are considered as the main sources of nitrate in the human diet. In order to investigate the effect of nitrate levels and harvest times on nitrate accumulation, nitrate reductase activity, concentrations of Fe, Zn, Cu and K in Lettuce and Spinach and their relation to nitrate accumulation in these leafy vegetables, two harvest times (29 and 46 days after transplanting), two vegetable species of lettuce and spinach and two concentrations of nitrate (10 and 20 mM) were used in ...

  3. The use of cerium(IV) phosphate for the gravimetric determination and separation of cerium

    International Nuclear Information System (INIS)

    Masin, V.; Dolezal, J.

    1978-01-01

    A method for the gravimetric determination of cerium as Ce 3 (PO 4 ) 4 is described. Cerium can be separated from many metals in this form, as well as from permanganate and dichromate; the cerium separated can then be titrated with iron(II) solution. The method was verified for the determination of cerium in a rare earth concentrate. (Auth.)

  4. Two-phase titration of cerium(III) by permanganate

    International Nuclear Information System (INIS)

    Lazarev, A.I.; Lazareva, V.I.; Gerko, V.V.

    1987-01-01

    This paper presents a method for the two-phase titrimetric determination of cerium(III) with permanganate which does not require an expenditure of sugar and preliminary removal of chlorides and nitrates. The interaction of cerium(III) with permanganate at room temperature was studied as a function of the pH, the concentration of pyrophosphate, tetraphenylphosphonium (TPP), permanganate, and extraneous compounds, the rate of titration, and the time of stay of the solution in air before titration. The investigations were conducted according to the following methodology: water, solution of cerium(III) pyrophosphate, and TPP were introduced into an Erlenmeyer flask with a side branch near the bottom for clearer observation of the color of the chloroform phase. The authors established the given pH value, poured the water into a volume of 50 ml, and added chloroform. The result was titrated with permanganate solutions of various concentrations until a violet color appeared in the chloroform phase

  5. Estimating soil solution nitrate concentration from dielectric spectra using PLS analysis

    Science.gov (United States)

    Fast and reliable methods for in situ monitoring of soil nitrate-nitrogen concentration are vital for reducing nitrate-nitrogen losses to ground and surface waters from agricultural systems. While several studies have been done to indirectly estimate nitrate-nitrogen concentration from time domain s...

  6. Spatial and temporal analysis of the nitrate concentrations in groundwater for South Africa

    CSIR Research Space (South Africa)

    Maherry, A

    2009-11-01

    Full Text Available associated with agricultural stock farming. The Northern Cape Province, in particular the Kalahari has elevated nitrate levels, but a distinct lack of recent sampling may mask the extent of the current spatial distribution of nitrate concentrations...

  7. High-nitrate vegetable diet increases plasma nitrate and nitrite concentrations and reduces blood pressure in healthy women.

    Science.gov (United States)

    Ashworth, Ann; Mitchell, Klaus; Blackwell, Jamie R; Vanhatalo, Anni; Jones, Andrew M

    2015-10-01

    Epidemiological studies suggest that green leafy vegetables, which are high in dietary nitrate, are protective against CVD such as stroke. High blood pressure (BP) is a major risk factor for stroke and inorganic nitrate has been shown to reduce BP. The objective of the present study was to test the hypothesis that diets containing high-nitrate (HN) vegetables would increase plasma nitrate and nitrite concentrations and reduce BP in healthy women. A randomized, crossover trial, where participants received HN vegetables (HN diet) or avoided HN vegetables (Control diet) for 1 week. Before and after each intervention, resting BP and plasma nitrate and nitrite concentrations were measured. University of Exeter, UK. Nineteen healthy women (mean age 20 (sd 2) years; mean BMI 22·5 (sd 3·8) kg/m2). The HN diet significantly increased plasma nitrate concentration (before HN diet: mean 24·4 (sd 5·6) µmol/l; after HN diet: mean 61·0 (sd 44·1) µmol/l, Pdiet: mean 98 (sd 91) nmol/l; after HN diet: mean 185 (sd 34) nmol/l, Pdiet. The HN diet significantly reduced resting systolic BP (before HN diet: mean 107 (sd 9) mmHg; after HN diet: mean 103 (sd 6) mmHg, Pdiet (before Control diet: mean 106 (sd 8) mmHg; after Control diet: mean 106 (sd 8) mmHg). Consumption of HN vegetables significantly increased plasma nitrate and nitrite concentrations and reduced BP in normotensive women.

  8. MODELING NITRATE CONCENTRATION IN GROUND WATER USING REGRESSION AND NEURAL NETWORKS

    OpenAIRE

    Ramasamy, Nacha; Krishnan, Palaniappa; Bernard, John C.; Ritter, William F.

    2003-01-01

    Nitrate concentration in ground water is a major problem in specific agricultural areas. Using regression and neural networks, this study models nitrate concentration in ground water as a function of iron concentration in ground water, season and distance of the well from a poultry house. Results from both techniques are comparable and show that the distance of the well from a poultry house has a significant effect on nitrate concentration in groundwater.

  9. High nitrate concentrations in some Midwest United States streams in 2013 after the 2012 drought

    Science.gov (United States)

    Van Metre, Peter C.; Frey, Jeffrey W.; Musgrove, MaryLynn; Nakagaki, Naomi; Qi, Sharon L.; Mahler, Barbara J.; Wieczorek, Michael; Button, Daniel T.

    2016-01-01

    Nitrogen sources in the Mississippi River basin have been linked to degradation of stream ecology and to Gulf of Mexico hypoxia. In 2013, the USGS and the USEPA characterized water quality stressors and ecological conditions in 100 wadeable streams across the midwestern United States. Wet conditions in 2013 followed a severe drought in 2012, a weather pattern associated with elevated nitrogen concentrations and loads in streams. Nitrate concentrations during the May to August 2013 sampling period ranged from nitrate concentrations at the 100 sites were compared with May to June concentrations predicted from a regression model developed using historical nitrate data. Observed concentrations for 17 sites, centered on Iowa and southern Minnesota, were outside the 95% confidence interval of the regression-predicted mean, indicating that they were anomalously high. The sites with a nitrate anomaly had significantly higher May to June nitrate concentrations than sites without an anomaly (means, 19.8 and 3.6 mg L−1, respectively) and had higher antecedent precipitation indices, a measure of the departure from normal precipitation, in 2012 and 2013. Correlations between nitrate concentrations and watershed characteristics and nitrogen and oxygen isotopes of nitrate indicated that fertilizer and manure used in crop production, principally corn, were the dominant sources of nitrate. The anomalously high nitrate levels in parts of the Midwest in 2013 coincide with reported higher-than-normal nitrate loads in the Mississippi River.

  10. The Effect of Nitrate Levels and Harvest Times on Fe, Zn, Cu, and K, Concentrations and Nitrate Reductase Activity in Lettuce and Spinach

    Directory of Open Access Journals (Sweden)

    Z. Gheshlaghi

    2015-09-01

    Full Text Available Leafy vegetables are considered as the main sources of nitrate in the human diet. In order to investigate the effect of nitrate levels and harvest times on nitrate accumulation, nitrate reductase activity, concentrations of Fe, Zn, Cu and K in Lettuce and Spinach and their relation to nitrate accumulation in these leafy vegetables, two harvest times (29 and 46 days after transplanting, two vegetable species of lettuce and spinach and two concentrations of nitrate (10 and 20 mM were used in a hydroponics greenhouse experiment with a completely randomized design and 3 replications. Modified Hoagland and Arnon nutrient solutions were used for the experiment. The results indicated that by increasing nitrate concentration of solution, nitrate accumulation in roots and shoots of lettuce and spinach increased significantly (P ≤ 0.05, and the same trend was observed for the nitrate reductase activity in the shoots of the two species. Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species, where as it increased the K and Zn concentrations in the shoots of the two species in each both harvest times, the nitrate accumulation increased, but the nitrate reductase activity decreased in the shoots of the two species over the course of the growth. The Concentration of Fe, Cu and K decreased in the shoots of lettuce and the spinach with the time, despite the increase in Zn concentration in the shoots. The results also indicated that increasing nitrate concentrations of solution to the levels greater than the plant capacity for reduction and net uptake of nitrate, leads to the nitrate accumulation in the plants. Nitrate accumulation in plant tissue led to decreases in fresh shoot yield and Fe and Cu concentrations and nitrate reductase activities in both lettuce and spinach.

  11. Strontium, cessium, and cerium radioisotope concentration in water of superficial reservoirs as determined by their accumulation in alga Cladophora glomerata

    International Nuclear Information System (INIS)

    Piskunov, L.I.; Gushchin, V.M.

    1979-01-01

    An indirect method of measuring concentrations of strontium-90,cesium-137 and cerium-144 in water is considered. The method is bsed on the accumulation of the nuclides in Cladophora glomerata Kutz, a fresh-water alga. During 10 days in the end of July, 1975, water samples (20 l) and alga samples (about 1 kg) were taken at 14 locations more or less evenly distributed along the bank of reservoir. Some locations were in coves or issues of small rivers so that almost all morphometric features of the reservoir were taken into account. The samples were processed and radiochemically analyzed, including the radiometry of standard techniques. The counting time was so selected that the statistical error did not exceed 10 %. The radionuclide concentration was calculated per unit weight of sample (pCi/l or pCi/kg of natural alga biomass). The method may be of particular importance for those radionuclides that are rapidly absorbed by bottom sediments and at the same time intensively accumulated by the hydrobios (radioisotopes of iron, cobalt, zinc, yttrium, zirconium and some others)

  12. Assessing bottled water nitrate concentrations to evaluate total drinking water nitrate exposure and risk of birth defects.

    Science.gov (United States)

    Weyer, Peter J; Brender, Jean D; Romitti, Paul A; Kantamneni, Jiji R; Crawford, David; Sharkey, Joseph R; Shinde, Mayura; Horel, Scott A; Vuong, Ann M; Langlois, Peter H

    2014-12-01

    Previous epidemiologic studies of maternal exposure to drinking water nitrate did not account for bottled water consumption. The objective of this National Birth Defects Prevention Study (NBDPS) (USA) analysis was to assess the impact of bottled water use on the relation between maternal exposure to drinking water nitrate and selected birth defects in infants born during 1997-2005. Prenatal residences of 1,410 mothers reporting exclusive bottled water use were geocoded and mapped; 326 bottled water samples were collected and analyzed using Environmental Protection Agency Method 300.0. Median bottled water nitrate concentrations were assigned by community; mothers' overall intake of nitrate in mg/day from drinking water was calculated. Odds ratios for neural tube defects, limb deficiencies, oral cleft defects, and heart defects were estimated using mixed-effects models for logistic regression. Odds ratios (95% CIs) for the highest exposure group in offspring of mothers reporting exclusive use of bottled water were: neural tube defects [1.42 (0.51, 3.99)], limb deficiencies [1.86 (0.51, 6.80)], oral clefts [1.43 (0.61, 3.31)], and heart defects [2.13, (0.87, 5.17)]. Bottled water nitrate had no appreciable impact on risk for birth defects in the NBDPS.

  13. High frequency measurement of nitrate concentration in the Lower Mississippi River, USA

    Science.gov (United States)

    Duan, Shuiwang; Powell, Rodney T.; Bianchi, Thomas S.

    2014-11-01

    Nutrient concentrations in the Mississippi River have increased dramatically since the 1950s, and high frequency measurements on nitrate concentration are required for accurate load estimations and examinations on nitrate transport and transformation processes. This three year record of high temporal resolution (every 2-3 h) data clearly illustrates the importance of high frequency sampling in improving load estimates and resolving variations in nitrate concentration with river flow and tributary inputs. Our results showed large short-term (days to weeks) variations in nitrate concentration but with no diurnal patterns. A repeatable and pronounced seasonal pattern of nitrate concentration was observed, and showed gradual increases from the lowest values in September (during base-flow), to the highest in June - which was followed by a rapid decrease. This seasonal pattern was only moderately linked with water discharge, and more controlled by nitrogen transformation/export from watershed as well as mixing patterns of the two primary tributaries (the upper Mississippi and the Ohio Rivers), which have distinctly different nitrate concentrations and flow patterns. Based on continuous in situ flow measurements, we estimated 554-886 × 106 kg of nitrate-N was exported from the Mississippi River system during years 2004-2006, which was <9% and <16% lower than U.S. Geological Survey's (USGS) estimates using their LOADEST or composite methods, respectively. USGS methods generally overestimated nitrate loads during rising stages and underestimated the loads during falling stages. While changes in nitrate concentrations in large rivers are generally not as responsive to alterations in diurnal inputs and/or watershed hydrology as small rivers, high-frequency water quality sampling would help in monitoring short-term (days to weeks) variations in nutrient concentration patterns and thus improve the accuracy of nutrient flux estimates.

  14. Effects of over-winter green cover on soil solution nitrate concentrations beneath tillage land.

    Science.gov (United States)

    Premrov, Alina; Coxon, Catherine E; Hackett, Richard; Kirwan, Laura; Richards, Karl G

    2014-02-01

    There is a growing need to reduce nitrogen losses from agricultural systems to increase food production while reducing negative environmental impacts. The efficacy of vegetation cover for reducing nitrate leaching in tillage systems during fallow periods has been widely investigated. Nitrate leaching reductions by natural regeneration (i.e. growth of weeds and crop volunteers) have been investigated to a lesser extent than reductions by planted cover crops. This study compares the efficacy of natural regeneration and a sown cover crop (mustard) relative to no vegetative cover under both a reduced tillage system and conventional plough-based system as potential mitigation measures for reducing over-winter soil solution nitrate concentrations. The study was conducted over three winter fallow seasons on well drained soil, highly susceptible to leaching, under temperate maritime climatic conditions. Mustard cover crop under both reduced tillage and conventional ploughing was observed to be an effective measure for significantly reducing nitrate concentrations. Natural regeneration under reduced tillage was found to significantly reduce the soil solution nitrate concentrations. This was not the case for the natural regeneration under conventional ploughing. The improved efficacy of natural regeneration under reduced tillage could be a consequence of potential stimulation of seedling germination by the autumn reduced tillage practices and improved over-winter plant growth. There was no significant effect of tillage practices on nitrate concentrations. This study shows that over winter covers of mustard and natural regeneration, under reduced tillage, are effective measures for reducing nitrate concentrations in free draining temperate soils. © 2013.

  15. Determination, Source Identification and GIS Mapping for Nitrate Concentration in Groundwater from Bara Aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Elami, G. M.; Sam, A. K.; Yagob, T. I.; Siddeeg, S. E.M.B.; Hatim, E.; Hajo, I. [Sudan Atomic Energy Commission, Sudan, Khartoum (Sudan)

    2013-07-15

    This study was carried out to determine the level of nitrate concentration in well water from Bara aquifer in north Kordofan state (west central sudan). The analysis was conducted for 69 wells from different villages within the Bara basin. Spectophotometric analysis was used to determine nitrate, nitrite and ammonia. Results revealed that nitrate concentration range was from 9.68 to 891 mg L in the sampled well with 81% exceeding the maximum permissible limits set for drinking water by WHO and SSMO. Animal waste and organic soil nitrogen were found to be the source of nitrate in these wells as indicated by {sup 15}N. The majority of wells with high nitrate are in the north and the north east part of the study area are shown by the GIS predictive map. (author)

  16. The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150

    International Nuclear Information System (INIS)

    Wang, L.; Stuart, M.E.; Lewis, M.A.; Ward, R.S.; Skirvin, D.; Naden, P.S.; Collins, A.L.; Ascott, M.J.

    2016-01-01

    Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses. - Highlights: • An approach to modelling groundwater nitrate at the national scale is presented. • The long time-lag for nitrate in the

  17. The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L., E-mail: lei.wang@bgs.ac.uk [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Stuart, M.E.; Lewis, M.A. [British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Ward, R.S. [British Geological Survey, Keyworth, Nottingham NG12 5GG (United Kingdom); Skirvin, D. [ADAS UK Ltd., Pendeford House, Pendeford Business Park, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Naden, P.S. [Centre for Ecology and Hydrology, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Collins, A.L. [Sustainable Soils and Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton EX20 2SB (United Kingdom); Ascott, M.J. [British Geological Survey, Maclean Building, Wallingford, Oxfordshire OX10 8BB (United Kingdom)

    2016-01-15

    Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses. - Highlights: • An approach to modelling groundwater nitrate at the national scale is presented. • The long time-lag for nitrate in the

  18. Correlation between nitrate concentration in groundwater and parameters affecting aquifer intrinsic vulnerability

    Science.gov (United States)

    Debernardi, Laura; de Luca, Domenico Antonio; Lasagna, Manuela

    2008-08-01

    This paper is the result of a study which was carried out in order to verify if the traditional methods to evaluate the intrinsic vulnerability or vulnerability related parameters, are able to clarify the problem of nitrate pollution in groundwater. In particular, the aim was to evaluate limitations and problems connected to aquifer vulnerability methods applied to nitrate contamination prevision in groundwater. The investigation was carried out by comparing NO3 - concentrations, measured in March and November 2004 in the shallow aquifer, and the vulnerability classes, obtained by using GOD and TOT methods. Moreover, it deals with a comparison between NO3 - concentrations and single parameters (depth to water table, land use and nitrogen input). The study area is the plain sector of Piemonte (Northern Italy), where an unconfined aquifer nitrate contamination exists. In this area the anthropogenic presence is remarkable and the input of N-fertilizers and zootechnical effluents to the soil cause a growing amount of nitrates in groundwater. This approach, used in a large area (about 10,000 km2) and in several monitoring wells (about 500), allowed to compare the efficiency of different vulnerability methods and to verify the importance of every parameter on the nitrate concentrations in the aquifer. Furthermore it allowed to obtain interesting correlations in different hydrogeological situations. Correlations between depth to water table, land use and nitrogen input to the soil with nitrate concentrations in groundwater show unclear situations: in fact these comparisons describe the phenomenon trend and highlight the maximum nitrate concentrations for each circumstance but often show wide ranges of possible nitrate concentrations. The same situation could be observed by comparing vulnerability indexes and nitrate concentrations in groundwater. These results suggest that neither single parameters nor vulnerability methods (GOD and TOT) are able to describe individually

  19. A study preliminary technician for the obtaining of concentrated de lanthanum and cerium to leave of national minerals

    International Nuclear Information System (INIS)

    Orrego A, P; Navarro D, Patricio; Mahu A, Susana; Vega V, Pilar

    1999-01-01

    A preliminary technical study was carried out to obtain concentrated oxides of Lanthanum (La) and Cerium (Ce), from a radioactively anomalous local mineral. This study is part of a joint project of the National Mining Company (ENAMI) and the Chilean Nuclear Energy Commission (CCHEN), G eological Investigation of Rare Earth in the Region III mountain range ; which aims to diversify the production of minerals that have potential economic interest in the short term. Three sections were defined over area of 100 km 2 , where the rare earth bearing metallic mineral is davidite ((AB-3(O, OH)-7), with A = Fe 2+ , RE, U, Ca, Na, Zr, Th; B = Ti 4+ , Fe 3+ U, V 3+ , Cr 3+ and varieties of anatase with Ti, RE, La, Ce and Nd. The metallurgical research includes the following stages: leaching with sulfuric acid, selective precipitation of purities and the rare earth, evaluating the reagents sodium hydroxide and ammonium hydroxide, dissolution of the precipitates containing rare earth with nitric acid and later precipitation with oxalic acid. According to the results obtained in the laboratory tests, the best operating conditions would be: (1) Leaching R(S/L) = 1, dosage 500 kg of acid /ton mineral; 90 , (2) Precipitation of impurities Ammonium Hydroxide, pH = 4.5 at 90 , (3) Precipitation elements of RE Ammonium Hydroxide, pH 7,5 at 90 , (4) Dissolution HNO-3, 70 , (5) Oxalic precipitation Oxalic acid, pH ∼ 1,0 at 70 . The results of each stage were evaluated with the following major points: Sulfuric acid is not a good leaching agent under normal conditions of temperature and pressure. For sulfuric solutions ammonium hydroxide provides the best precipitation efficiencies. Selective precipitation with oxalic acid produces bigger lanthanide recovery at a pH of less than 1.0. By means this design a concentrate of oxides of rare earth with an approximate of 43% may be obtained

  20. Median nitrate concentrations in groundwater in the New Jersey Highlands Region estimated using regression models and land-surface characteristics

    Science.gov (United States)

    Baker, Ronald J.; Chepiga, Mary M.; Cauller, Stephen J.

    2015-01-01

    Nitrate-concentration data are used in conjunction with land-use and land-cover data to estimate median nitrate concentrations in groundwater underlying the New Jersey (NJ) Highlands Region. Sources of data on nitrate in 19,670 groundwater samples are from the U.S. Geological Survey (USGS) National Water Information System (NWIS) and the NJ Private Well Testing Act (PWTA).

  1. Mechanism of bactericidal activity of Silver Nitrate - a concentration dependent bi-functional molecule

    Directory of Open Access Journals (Sweden)

    Sureshbabu Ram Kumar Pandian

    2010-10-01

    Full Text Available Silver nitrate imparts different functions on bacteria depending upon its concentration. At lower concentration it induced synthesis of nanoparticles, whereas at higher concentrations it induced cell death. Bacillus licheniformis was used as model system. The MIC was 5 mM, and it induced catalase production, apoptotic body formation and DNA fragmentation.

  2. Nitrate concentration in spring water at the Nogawa basin and its possible source

    International Nuclear Information System (INIS)

    Yoshida, Kazuhiro; Ogura, Norio

    1978-01-01

    Fluctuation of nitrate concentration in spring water at the Nogawa basin was studied during 1976 - 1977, and the possible source of nitrate nitrogen was discussed. Nitrate concentration in spring water at the station N-O in Kokubunji, Tokyo ranged from 360 to 574 μg at/l with an average value of 502 μg at/l. It seemed that the effluent of spring water at N-O was influenced by rainfall within a short period. A laboratory experiment on production of nitrate in soil showed that ammonium nitrogen added to fresh soil was transformed quantitatively to nitrate nitrogen during 23 days incubation. Thd sup(delta15)N value of nitrate nitrogen in spring water (+0.89%) was similar to that of ammonium nitrogen in sewage (+0.82%) discharging into the Nogawa River. In the area near N-O, domestic wastes have been discharged into the Nogawa River by simple sewers or percolated downward through the soil. These results suggest that one of the main source of nitrate nitrogen in spring water is ammonium and organic nitrogen in domestic wastes. (author)

  3. Effects of groundwater-flow paths on nitrate concentrations across two riparian forest corridors

    Science.gov (United States)

    Speiran, Gary K.

    2010-01-01

    Groundwater levels, apparent age, and chemistry from field sites and groundwater-flow modeling of hypothetical aquifers collectively indicate that groundwater-flow paths contribute to differences in nitrate concentrations across riparian corridors. At sites in Virginia (one coastal and one Piedmont), lowland forested wetlands separate upland fields from nearby surface waters (an estuary and a stream). At the coastal site, nitrate concentrations near the water table decreased from more than 10 mg/L beneath fields to 2 mg/L beneath a riparian forest buffer because recharge through the buffer forced water with concentrations greater than 5 mg/L to flow deeper beneath the buffer. Diurnal changes in groundwater levels up to 0.25 meters at the coastal site reflect flow from the water table into unsaturated soil where roots remove water and nitrate dissolved in it. Decreases in aquifer thickness caused by declines in the water table and decreases in horizontal hydraulic gradients from the uplands to the wetlands indicate that more than 95% of the groundwater discharged to the wetlands. Such discharge through organic soil can reduce nitrate concentrations by denitrification. Model simulations are consistent with field results, showing downward flow approaching toe slopes and surface waters to which groundwater discharges. These effects show the importance of buffer placement over use of fixed-width, streamside buffers to control nitrate concentrations.

  4. Temporal and spatial trends in streamwater nitrate concentrations in the San Bernardino mountains, southern California

    Science.gov (United States)

    Mark E. Fenn; Mark A. Poth

    1999-01-01

    We report streamwater nitrate (NO,) concentrations for December 1995 to September 1998 from 19 sampling sites across a N deposition gradient in the San Bernardino Mountains. Streamwater NO3- concentrations in Devil Canyon (DC), a high-pollution area, and in previously reported data from the San Gabriel Mountains 40 km...

  5. CONCENTRATED CALCIUM NITRATE IS AN EFFECTIVE SOLUTION FOR MINERAL NUTRITION OF VEGETABLES GROWN THROUGH PROTECTED CULTIVATION

    Directory of Open Access Journals (Sweden)

    T. V. Grebennikova

    2017-01-01

    Full Text Available One of the basis water-soluble fertilizers that are used in greenhouse enterprises is  a Calcium  nitrate,  where  its production  and demand raise. At present time, calcium nitrate is produced  in a granulated and crystaline   form consisted of tetrahydrate, dihydrate and concentrated variants. These forms  are significantly distinguished  by their  chemical  composition.  Besides the  basic  form  of nitrogen – nitrate – there is ammoniacal nitrogen in the composition of Calcium nitrate that is found to be undesirable element, particularly with drip irrigation system in the  greenhouse. The new  product,  calcium  nitrate  has been worked out with minimal content of ammoniacal nitrogen  at  URALCHIM. The study  showed  the  advantages of the product for such characteristics as solubility and time of dissolving. It dissolves 3.4-7 time faster than those of tetrahydrate and dihydrate analogues. At present time, the concentrated  calcium  nitrate is used in many greenhouse  industrial  complexes  and  enterprises,  and has shown its efficiency in practice.

  6. Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence

    DEFF Research Database (Denmark)

    Hansen, B.; Dalgaard, Tommy; Thorling, L.

    2012-01-01

    The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have...... succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30–55% from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture......, approximately 48% of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l−1. Furthermore, trend analyses show that 33% of all the monitored groundwater has upward nitrate trends, while only 18% of the youngest groundwater has upward nitrate...

  7. Nitrate response of a lowland catchment: On the relation between stream concentration and travel time distribution dynamics

    NARCIS (Netherlands)

    Velde, Y. van der; Rooij, G.H. de; Rozemeijer, J.C.; Geer, F.C. van; Broers, H.P.

    2010-01-01

    Nitrate pollution of surface waters is widespread in lowland catchments with intensive agriculture. For identification of effective nitrate concentration reducing measures the nitrate fluxes within catchments need to be quantified. In this paper we applied a mass transfer function approach to

  8. The nitrate response of a lowland catchment: on the relation between stream concentration and travel time distribution dynamics

    NARCIS (Netherlands)

    Velde, van der Y.; Rooij, de G.H.; Rozemeijer, J.C.; Geer, van F.C.; Broers, H.P.

    2010-01-01

    Nitrate pollution of surface waters is widespread in lowland catchments with intensive agriculture. For identification of effective nitrate concentration reducing measures the nitrate fluxes within catchments need to be quantified. In this paper we applied a mass transfer function approach to

  9. Chemical perspectives on alkali and earth alkaline nitrate and nitrite salts for concentrated solar power applications

    Energy Technology Data Exchange (ETDEWEB)

    Cordaro, Joseph G. [Sandia National Labsoratories, Livermore, CA (United States)

    2013-04-01

    Molten salts have been widely considered as the leading candidate heat transfer fluids (HTF) used in high temperature, concentrated solar power plants. Specifically, nitrate and nitrite based salts have been investigated as a HTF and even deployed in pilot plants generating up to 19.9 MW of electricity at operating temperatures above 500 C. New plant designs requiring higher operating temperatures for better efficiencies are pushing the stability limit of HTF. This paper presents an overview of the thermophysical properties of nitrate and nitrite salts and discusses thermodynamic and kinetic stability limitations as they relate to concentrated solar power generation. (orig.)

  10. Improved daily precipitation nitrate and ammonium concentration models for the Chesapeake Bay Watershed

    International Nuclear Information System (INIS)

    Grimm, J.W.; Lynch, J.A.

    2005-01-01

    Daily precipitation nitrate and ammonium concentration models were developed for the Chesapeake Bay Watershed (USA) using a linear least-squares regression approach and precipitation chemistry data from 29 National Atmospheric Deposition Program/National Trends Network (NADP/NTN) sites. Only weekly samples that comprised a single precipitation event were used in model development. The most significant variables in both ammonium and nitrate models included: precipitation volume, the number of days since the last event, a measure of seasonality, latitude, and the proportion of land within 8 km covered by forest or devoted to industry and transportation. Additional variables included in the nitrate model were the proportion of land within 0.8 km covered by water and/or forest. Local and regional ammonia and nitrogen oxide emissions were not as well correlated as land cover. Modeled concentrations compared very well with event chemistry data collected at six NADP/AirMoN sites within the Chesapeake Bay Watershed. Wet deposition estimates were also consistent with observed deposition at selected sites. Accurately describing the spatial distribution of precipitation volume throughout the watershed is important in providing critical estimates of wet-fall deposition of ammonium and nitrate. - A linear least-squares regression approach was used to develop daily precipitation nitrate and ammonium concentration models for the Chesapeake Bay Watershed

  11. Determination, source identification and GIS mapping for nitrate concentration in ground water from Bara aquifer

    International Nuclear Information System (INIS)

    Elfaki Taha, G. M. E.

    2010-09-01

    The study was carried-out determine the level of nitrate concentration in well water from Bara aquifer in North Kordofan State. The analysis was conducted for 69 wells from different villages within Bara basin. Physical characteristics were measured including pH, electrical conductivity and dissolved oxygen. Spectrophotometric analysis was used to determine nitrate, nitrite and ammonia. Chloride and hardness were determined telemetrically and flame photometer was used for major elements namely sodium and potassium, whereas atomic absorption spectroscopy was used for trace elements namely iron, manganese, zinc and copper. Results revealed that nitrate concentration range from 9.68 to 891 mg/1 in sampled wells with 81% exceeding the maximum permissible limits set for drinking water by WHO and SSMO. Animal waste and organic soil nitrogen were found to be the sources of nitrate in these wells as indicated by 15 N%. Majority of wells with high nitrate are located in the north and the north-east part of the study area as shown by GIS predictive map. On the average, the concentrations of sodium, potassium, calcium, magnesium, iron, manganese, zinc and copper were found to be within WHO limits for drinking water. (Author)

  12. Determination of cyanide and nitrate concentrations in drinking, irrigation, and wastewaters

    Directory of Open Access Journals (Sweden)

    Seyed Reza Mousavi

    2013-01-01

    Full Text Available Background: The chemical contamination of water is a major concern for the environmental and health authorities globally. Some anions present in the water are required for human health, but some of them are harmful. Free cyanide and nitrate are amongst the toxic agents in the aquatic environment. Cyanide is highly toxic for human beings. Industrial plants could be attributed to a major source of these toxic agents. Therefore, cyanide and nitrate concentrations in the drinking and irrigation water wells in the high industrial plants were evaluated. Materials and Methods: The samples (57 were taken from drinking and irrigation water wells as well as from a wastewater refinery in north of Mashhad in three stages - March 2009, June 2010, and July 2010. Determination of cyanide and nitrate were performed by a spectrophotometer using commercially available kits according to the manufacturer′s protocols. Results: Cyanide and nitrate concentrations in the drinking water samples of the three stages were 0.0050 ± 0.0007, 0.0070 ± 0.0018, 0.0008 ± 0.0014 mg/L and 6.50 ± 2.80, 7.20 ± 1.80, 7.50 ± 1.90 mg/L, respectively. Cyanide mean concentration during March, June, and July was significant (P = 0.001, whereas nitrate mean concentration was not (P = 0.5. Cyanide and nitrate concentrations in the irrigation water samples of the three stages were 0.0140 ± 0.0130, 0.0077 ± 0.0025, 0.0087 ± 0.0047 mg/L and 12.37 ± 8.12, 8.04 ± 3.99, 8.40 ± 2.60 mg/L, respectively. Cyanide (P = 0.754 and nitrate (P = 0.705 concentrations were not significant during three occasions. Cyanide and nitrate concentrations in the wastewaters of the three stages were 0.1020 ± 0.033, 0.1180 ± 0.033, 0.1200 ± 0.035 mg/L and 1633.80 ± 40.74, 279.00 ± 152.17, 298.40 ± 304.74 mg/L, respectively. Cyanide (P = 0.731 and nitrate (P = 0.187 concentration in wastewaters were not significant during different months. Conclusion: Although nitrate and cyanide concentrations in

  13. Effect of cation type and concentration of nitrates on neurological disorders during experimental cerebral ischemia.

    Science.gov (United States)

    Kuzenkov, V S; Krushinskii, A L; Reutov, V P

    2013-10-01

    Experiments were performed on the model of ischemic stroke due to bilateral occlusion of the carotid arteries. Nitrates had various effects on the dynamics of neurological disorders and mortality rate of Wistar rats, which depended on the cation type and concentration.

  14. NITRATE AND NITROUS OXIDE CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    Science.gov (United States)

    We are measuring dissolved nitrate and nitrous oxide concentrations and related parameters in 17 headwater streams in the South Fork Broad River, Georgia watershed on a monthly basis. The selected small streams drain watersheds dominated by forest, pasture, residential, or mixed...

  15. Simulations of monthly mean nitrate concentrations in precipitation over East Asia

    International Nuclear Information System (INIS)

    Junling An; Xinjin Cheng; Ueda, Hiromasa; Kajino, Mizuo

    2002-01-01

    Monthly mean nitrate concentrations in precipitation over East Asia (10-55 o N, 75-155 o E) in April, July, September, and December of 1999 were simulated by using a regional air quality Eulerian model (RAQM) with meteorological fields four times per day taken from National Centers for Environmental Prediction. The distribution of the nitrate concentration in precipitation depends significantly on the emission patterns of nitrogen oxides (NO x =NO+NO 2 ) and volatile organic compound (VOC) and seasonal precipitation variability. The downward trend is also revealed, particularly on July and December. Highest concentrations are found in the industrialized regions, i.e., the coastal area of the Mainland of China, the Bay of the Huanghai Sea and the Bohai Sea, Korea, and Southern Japan. Long-range transport may cause elevated concentrations in remote areas downwind of the industrialized regions under favorable meteorological conditions, e.g., low precipitation. Comparison of observation and simulations indicates that the RAQM model reasonably predicts synoptic-scale changes in different months (seasons) and simulated nitrate levels in 4 months fit observed data with the discrepancy within a factor of 2. Exclusion of liquid chemistry within clouds is feasible for regional (1 o x1 o ) and long-term (monthly) nitrate simulations. The uncertainty originates mainly from that of the emission data and modeled precipitation amounts and initial and boundary conditions. (author)

  16. Soil water nitrate concentrations in giant cane and forest riparian buffer zones

    Science.gov (United States)

    Jon E. Schoonover; Karl W. J. Williard; James J. Zaczek; Jean C. Mangun; Andrew D. Carver

    2003-01-01

    Soil water nitrate concentrations in giant cane and forest riparian buffer zones along Cypress Creek in southern Illinois were compared to determine if the riparian zones were sources or sinks for nitrogen in the rooting zone. Suction lysimeters were used to collect soil water samples from the lower rooting zone in each of the two vegetation types. The cane riparian...

  17. Effects of substrate type on plant growth and nitrogen and nitrate concentration in spinach

    Science.gov (United States)

    The effects of three commercial substrates (a mixture of forest residues, composted grape husks, and white peat; black peat; and coir) on plant growth and nitrogen (N) and nitrate (NO3) concentration and content were evaluated in spinach (Spinacia oleracea L. cv. Tapir). Spinach seedlings were trans...

  18. Validation of regression models for nitrate concentrations in the upper groundwater in sandy soils

    International Nuclear Information System (INIS)

    Sonneveld, M.P.W.; Brus, D.J.; Roelsma, J.

    2010-01-01

    For Dutch sandy regions, linear regression models have been developed that predict nitrate concentrations in the upper groundwater on the basis of residual nitrate contents in the soil in autumn. The objective of our study was to validate these regression models for one particular sandy region dominated by dairy farming. No data from this area were used for calibrating the regression models. The model was validated by additional probability sampling. This sample was used to estimate errors in 1) the predicted areal fractions where the EU standard of 50 mg l -1 is exceeded for farms with low N surpluses (ALT) and farms with higher N surpluses (REF); 2) predicted cumulative frequency distributions of nitrate concentration for both groups of farms. Both the errors in the predicted areal fractions as well as the errors in the predicted cumulative frequency distributions indicate that the regression models are invalid for the sandy soils of this study area. - This study indicates that linear regression models that predict nitrate concentrations in the upper groundwater using residual soil N contents should be applied with care.

  19. Improved daily precipitation nitrate and ammonium concentration models for the Chesapeake Bay Watershed.

    Science.gov (United States)

    Grimm, J W; Lynch, J A

    2005-06-01

    Daily precipitation nitrate and ammonium concentration models were developed for the Chesapeake Bay Watershed (USA) using a linear least-squares regression approach and precipitation chemistry data from 29 National Atmospheric Deposition Program/National Trends Network (NADP/NTN) sites. Only weekly samples that comprised a single precipitation event were used in model development. The most significant variables in both ammonium and nitrate models included: precipitation volume, the number of days since the last event, a measure of seasonality, latitude, and the proportion of land within 8km covered by forest or devoted to industry and transportation. Additional variables included in the nitrate model were the proportion of land within 0.8km covered by water and/or forest. Local and regional ammonia and nitrogen oxide emissions were not as well correlated as land cover. Modeled concentrations compared very well with event chemistry data collected at six NADP/AirMoN sites within the Chesapeake Bay Watershed. Wet deposition estimates were also consistent with observed deposition at selected sites. Accurately describing the spatial distribution of precipitation volume throughout the watershed is important in providing critical estimates of wet-fall deposition of ammonium and nitrate.

  20. Groundwater nitrate concentration evolution under climate change and agricultural adaptation scenarios: Prince Edward Island, Canada

    Science.gov (United States)

    Paradis, Daniel; Vigneault, Harold; Lefebvre, René; Savard, Martine M.; Ballard, Jean-Marc; Qian, Budong

    2016-03-01

    Nitrate (N-NO3) concentration in groundwater, the sole source of potable water in Prince Edward Island (PEI, Canada), currently exceeds the 10 mg L-1 (N-NO3) health threshold for drinking water in 6 % of domestic wells. Increasing climatic and socio-economic pressures on PEI agriculture may further deteriorate groundwater quality. This study assesses how groundwater nitrate concentration could evolve due to the forecasted climate change and its related potential changes in agricultural practices. For this purpose, a tridimensional numerical groundwater flow and mass transport model was developed for the aquifer system of the entire Island (5660 km2). A number of different groundwater flow and mass transport simulations were made to evaluate the potential impact of the projected climate change and agricultural adaptation. According to the simulations for year 2050, N-NO3 concentration would increase due to two main causes: (1) the progressive attainment of steady-state conditions related to present-day nitrogen loadings, and (2) the increase in nitrogen loadings due to changes in agricultural practices provoked by future climatic conditions. The combined effects of equilibration with loadings, climate and agricultural adaptation would lead to a 25 to 32 % increase in N-NO3 concentration over the Island aquifer system. The change in groundwater recharge regime induced by climate change (with current agricultural practices) would only contribute 0 to 6 % of that increase for the various climate scenarios. Moreover, simulated trends in groundwater N-NO3 concentration suggest that an increased number of domestic wells (more than doubling) would exceed the nitrate drinking water criteria. This study underlines the need to develop and apply better agricultural management practices to ensure sustainability of long-term groundwater resources. The simulations also show that observable benefits from positive changes in agricultural practices would be delayed in time due to

  1. Nitrite and nitrate concentrations and metabolism in breast milk, infant formula, and parenteral nutrition.

    Science.gov (United States)

    Jones, Jesica A; Ninnis, Janet R; Hopper, Andrew O; Ibrahim, Yomna; Merritt, T Allen; Wan, Kim-Wah; Power, Gordon G; Blood, Arlin B

    2014-09-01

    Dietary nitrate and nitrite are sources of gastric NO, which modulates blood flow, mucus production, and microbial flora. However, the intake and importance of these anions in infants is largely unknown. Nitrate and nitrite levels were measured in breast milk of mothers of preterm and term infants, infant formulas, and parenteral nutrition. Nitrite metabolism in breast milk was measured after freeze-thawing, at different temperatures, varying oxygen tensions, and after inhibition of potential nitrite-metabolizing enzymes. Nitrite concentrations averaged 0.07 ± 0.01 μM in milk of mothers of preterm infants, less than that of term infants (0.13 ± 0.02 μM) (P milk. Concentrations in parenteral nutrition were equivalent to or lower than those of breast milk. Freeze-thawing decreased nitrite concentration ~64%, falling with a half-life of 32 minutes at 37°C. The disappearance of nitrite was oxygen-dependent and prevented by ferricyanide and 3 inhibitors of lactoperoxidase. Nitrite concentrations in breast milk decrease with storage and freeze-thawing, a decline likely mediated by lactoperoxidase. Compared to adults, infants ingest relatively little nitrite and nitrate, which may be of importance in the modulation of blood flow and the bacterial flora of the infant GI tract, especially given the protective effects of swallowed nitrite. © 2013 American Society for Parenteral and Enteral Nutrition.

  2. Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

    Science.gov (United States)

    Yadav, Sushma; Chandra, Amalendu

    2017-12-01

    We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion pairing, and dynamics of water in the solvation shells and also of ion diffusion in aqueous solutions of divalent metal nitrate salts.

  3. Stochastic analysis to assess the spatial distribution of groundwater nitrate concentrations in the Po catchment (Italy)

    International Nuclear Information System (INIS)

    Cinnirella, Sergio; Buttafuoco, Gabriele; Pirrone, Nicola

    2005-01-01

    A large database including temporal trends of physical, ecological and socio-economic data was developed within the EUROCAT project. The aim was to estimate the nutrient fluxes for different socio-economic scenarios at catchment and coastal zone level of the Po catchment (Northern Italy) with reference to the Water Quality Objectives reported in the Water Framework Directive (WFD 2000/60/CE) and also in Italian legislation. Emission data derived from different sources at national, regional and local levels are referred to point and non-point sources. While non-point (diffuse) sources are simply integrated into the nutrient flux model, point sources are irregularly distributed. Intensive farming activity in the Po valley is one of the main Pressure factors Driving groundwater pollution in the catchment, therefore understanding the spatial variability of groundwater nitrate concentrations is a critical issue to be considered in developing a Water Quality Management Plan. In order to use the scattered point source data as input in our biogeochemical and transport models, it was necessary to predict their values and associated uncertainty at unsampled locations. This study reports the spatial distribution and uncertainty of groundwater nitrate concentration at a test site of the Po watershed using a probabilistic approach. Our approach was based on geostatistical sequential Gaussian simulation used to yield a series of stochastic images characterized by equally probable spatial distributions of the nitrate concentration across the area. Post-processing of many simulations allowed the mapping of contaminated and uncontaminated areas and provided a model for the uncertainty in the spatial distribution of nitrate concentrations. - The stochastic simulation should be preferred to kriging in environmental studies, whenever it is critical to preserve the variation of a variable

  4. Predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwestern United States

    Science.gov (United States)

    Anning, David W.; Paul, Angela P.; McKinney, Tim S.; Huntington, Jena M.; Bexfield, Laura M.; Thiros, Susan A.

    2012-01-01

    The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) is conducting a regional analysis of water quality in the principal aquifer systems across the United States. The Southwest Principal Aquifers (SWPA) study is building a better understanding of the susceptibility and vulnerability of basin-fill aquifers in the region to groundwater contamination by synthesizing baseline knowledge of groundwater-quality conditions in 16 basins previously studied by the NAWQA Program. The improved understanding of aquifer susceptibility and vulnerability to contamination is assisting in the development of tools that water managers can use to assess and protect the quality of groundwater resources.Human-health concerns and economic considerations associated with meeting drinking-water standards motivated a study of the vulnerability of basin-fill aquifers to nitrate con­tamination and arsenic enrichment in the southwestern United States. Statistical models were developed by using the random forest classifier algorithm to predict concentrations of nitrate and arsenic across a model grid that represents about 190,600 square miles of basin-fill aquifers in parts of Arizona, California, Colorado, Nevada, New Mexico, and Utah. The statistical models, referred to as classifiers, reflect natural and human-related factors that affect aquifer vulnerability to contamina­tion and relate nitrate and arsenic concentrations to explana­tory variables representing local- and basin-scale measures of source, aquifer susceptibility, and geochemical conditions. The classifiers were unbiased and fit the observed data well, and misclassifications were primarily due to statistical sampling error in the training datasets.The classifiers were designed to predict concentrations to be in one of six classes for nitrate, and one of seven classes for arsenic. Each classification scheme allowed for identification of areas with concentrations that were equal to or exceeding

  5. Seasonal dynamics of nitrate and ammonium ion concentrations in soil solutions collected using MacroRhizon suction cups.

    Science.gov (United States)

    Kabala, Cezary; Karczewska, Anna; Gałka, Bernard; Cuske, Mateusz; Sowiński, Józef

    2017-07-01

    The aims of the study were to analyse the concentration of nitrate and ammonium ions in soil solutions obtained using MacroRhizon miniaturized composite suction cups under field conditions and to determine potential nitrogen leaching from soil fertilized with three types of fertilizers (standard urea, slow-release urea, and ammonium nitrate) at the doses of 90 and 180 kg ha -1 , applied once or divided into two rates. During a 3-year growing experiment with sugar sorghum, the concentration of nitrate and ammonium ions in soil solutions was the highest with standard urea fertilization and the lowest in variants fertilized with slow-release urea for most of the months of the growing season. Higher concentrations of both nitrogen forms were noted at the fertilizer dose of 180 kg ha -1 . One-time fertilization, at both doses, resulted in higher nitrate concentrations in June and July, while dividing the dose into two rates resulted in higher nitrate concentrations between August and November. The highest potential for nitrate leaching during the growing season was in July. The tests confirmed that the miniaturized suction cups MacroRhizon are highly useful for routine monitoring the concentration of nitrate and ammonium ions in soil solutions under field conditions.

  6. Effect of arbuscular mycorrhizal and bacterial inocula on nitrate concentration in mesocosms simulating a wastewater treatment system relying on phytodepuration.

    Science.gov (United States)

    Lingua, Guido; Copetta, Andrea; Musso, Davide; Aimo, Stefania; Ranzenigo, Angelo; Buico, Alessandra; Gianotti, Valentina; Osella, Domenico; Berta, Graziella

    2015-12-01

    High nitrogen concentration in wastewaters requires treatments to prevent the risks of eutrophication in rivers, lakes and coastal waters. The use of constructed wetlands is one of the possible approaches to lower nitrate concentration in wastewaters. Beyond supporting the growth of the bacteria operating denitrification, plants can directly take up nitrogen. Since plant roots interact with a number of soil microorganisms, in the present work we report the monitoring of nitrate concentration in macrocosms with four different levels of added nitrate (0, 30, 60 and 90 mg l(-1)), using Phragmites australis, inoculated with bacteria or arbuscular mycorrhizal fungi, to assess whether the use of such inocula could improve wastewater denitrification. Higher potassium nitrate concentration increased plant growth and inoculation with arbuscular mycorrhizal fungi or bacteria resulted in larger plants with more developed root systems. In the case of plants inoculated with arbuscular mycorrhizal fungi, a faster decrease of nitrate concentration was observed, while the N%/C% ratio of the plants of the different treatments remained similar. At 90 mg l(-1) of added nitrate, only mycorrhizal plants were able to decrease nitrate concentration to the limits prescribed by the Italian law. These data suggest that mycorrhizal and microbial inoculation can be an additional tool to improve the efficiency of denitrification in the treatment of wastewaters via constructed wetlands.

  7. Investigations on uranyl nitrate solubility in nitric acid in different concentrations at temperatures of 50C

    International Nuclear Information System (INIS)

    Deigele, E.

    1983-01-01

    The solubility of uranyl nitrate was studied in nitric acid solutions of different concentrations at a temperature of 5 0 C. This temperature was chosen with a view to using water as coolant and to facilitate the handling of the strong acid solutions. Accurate curves were established by a multitude of accurate measurements in the high concentration range. Further solubility curves can be derived from this basic curve. Some of the precipitates in the interesting regions of the solubility curve were analyzed. (orig./EF) [de

  8. Simultaneous determination of Rn-220 and Rn-222 concentrations in atmospheres by cellulose nitrate ionographic detectors

    International Nuclear Information System (INIS)

    Lobao, N.

    1977-01-01

    A method for the indoor determination of airborne radon and radon daughters is described, based in the utilization of cellulose nitrate (CN) ionographic detectors (LR-115-Kodak-Pathe) These track-etching detectors are coupled to an air sample and to a difusion chamber respectively. In the first system ambient air is pulled through a fiber glass filter for collection of airborne radon daughters (Flow: 230 ml/min). In the second system, the cellulose nitrate detectors is coupled/min). In the second system, the cellulose nitrate detectors is coupled to a difusion chamber electrostatic precipitator arrangement. Here the CN detector will register only the alpha particles given off by the decay products of Rn-222 formed within the sensitive volume of electrostatic precipitator. The construction of calibration curves for the two systems using adequate steady-state concentrations of Rn-220 and Rn-222 in an exposure chamber (1 cubic meter), will allow the use of the system for measurement of measurement of averaged integrated radon concentrations. The CN attached to the CN attached to the air sampler is exposed in the reference atmosphere with and without a mylar filter for discrimination of alpha particles with different energies Field sampling indicated however, that efficiency of the two systems are still low for the measurement of environmental levels of Rn-220 and Rn-222 within houses of the AENR, recommendations for efficienty improvement of the system are proposed [pt

  9. Comparative study of glycine single crystals with additive of potassium nitrate in different concentration ratios

    Energy Technology Data Exchange (ETDEWEB)

    Gujarati, Vivek P., E-mail: vivekgujarati@gmail.com; Deshpande, M. P., E-mail: vishwadeshpande@yahoo.co.in; Patel, Kamakshi R.; Chaki, S. H. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat (India)

    2016-05-06

    Semi-organic crystals of Glycine Potassium Nitrate (GPN) with potential applications in Non linear optics (NLO) were grown using slow evaporation technique. Glycine and Potassium Nitrate were taken in three different concentration ratios of 3:1, 2:1 and 1:1 respectively. We checked the solubility of the material in distilled water at different temperatures and could observe the growth of crystals in 7 weeks time. Purity of the grown crystals was confirmed by Energy Dispersive X-ray Analysis (EDAX) and CHN analysis. GSN Powder X-ray diffraction pattern was recorded to confirm the crystalline nature. To confirm the applications of grown crystals in opto-electronics field, UV-Vis-NIR study was carried out. Dielectric properties of the samples were studied in between the frequency range 1Hz to 100 KHz.

  10. Concentration and transport of nitrate by the mat-forming sulphur bacterium Thioploca

    Science.gov (United States)

    Fossing, H.; Gallardo, V. A.; Jørgensen, B. B.; Hüttel, M.; Nielsen, L. P.; Schulz, H.; Canfield, D. E.; Forster, S.; Glud, R. N.; Gundersen, J. K.; Küver, J.; Ramsing, N. B.; Teske, A.; Thamdrup, B.; Ulloa, O.

    1995-04-01

    MARINE species of Thioploca occur over 3,000 km along the continental shelf off Southern Peru and North and Central Chile1-4. These filamentous bacteria live in bundles surrounded by a common sheath and form thick mats on the sea floor under the oxygen-minimum zone in the upwelling region, at between 40 and 280 m water depth. The metabolism of this marine bacterium5,6 remained a mystery until long after its discovery1,7. We report here that Thioploca cells are able to concentrate nitrate to up to 500 mM in a liquid vacuole that occupies >80% of the cell volume. Gliding filaments transport this nitrate 5-10 cm down into the sediment and reduce it, with concomitant oxidation of hydrogen sulphide, thereby coupling the nitrogen and sulphur cycles in the sediment.

  11. Fiber Bragg Grating Sensor for Detection of Nitrate Concentration in Water

    Directory of Open Access Journals (Sweden)

    A. S. LALASANGI

    2011-02-01

    Full Text Available The concentrations of chemical species in drinking water are of great interest. We demonstrated etched fiber Bragg grating (FBG as a concentration sensor for nitrate by analyzing the Bragg wavelength shift with concentration of chemical solution. The FBG is fabricated by phase mask technique on single mode Ge-B co-doped photosensitive fiber. Sensitivity of FBGs to the surrounding solution concentration can be enhanced by reducing diameter of the cladding with 40 % HF solution. The maximum sensitivity achieved is 1.322 ´ 10-3 nm/ppm. The overall shift of Bragg wavelength is of the order of 6.611 ´ 10-2 nm for 10 to 50 ppm concentration.

  12. Assessment of regional change in nitrate concentrations in groundwater in the Central Valley, California, USA, 1950s-2000s

    Science.gov (United States)

    Burow, Karen R.; Jurgens, Bryant C.; Belitz, Kenneth; Dubrovsky, Neil M.

    2013-01-01

    A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Overall, increasing trends in nitrate concentrations and the proportion of nitrate concentrations above 5 mg/L were observed in the east fans subregion of the Central Valley. Whereas the west fans subregion has elevated nitrate concentrations, temporal trends were not detected, likely due to the heterogeneous nature of the water quality in this area and geologic sources of nitrate, combined with sparse and uneven data coverage. Generally low nitrate concentrations in the basin subregion are consistent with reduced geochemical conditions resulting from low permeability soils and higher organic content, reflecting the distal portions of alluvial fans and historical groundwater discharge areas. Very small increases in the shallow aquifer in the basin subregion may reflect downgradient movement of high nitrate groundwater from adjacent areas or overlying intensive agricultural inputs. Because of the general lack of regionally extensive long-term monitoring networks, the results from this study highlight the importance of placing studies of trends in water quality into regional context. Earlier work concluded that nitrate concentrations were steadily increasing over time in the eastern San Joaquin Valley, but clearly those trends do not apply to other

  13. Measurement of Nitrate Concentration in Aqueous Media Using an Electrochemical Nanosensor Based on Silver Nanoparticles-Nanocellulose/Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Majid Shadfar

    2017-11-01

    Full Text Available Nitrate pollution is at the forefront of groundwater contamination which poses serious environmental and public health hazards.  Nitrate is usually released in solution from agricultural activities and finds its way into groundwater resources. The objective of the present study was to determine, accurately concentrations of nitrate ions in water samples from the environment using sensitive electrochemical methods. For this purpose, a modified glassy carbon electrode modified with a nanocomposite consisting of silver nanoparticles, nanocellulose, and graphene oxide (Ag/NC/GO-GCE was used. The characterization of the nanocomposite was investigated using scanning electron microscope (SEM, X-Ray diffraction (XRD, and electrochemical impedance spectroscopy (EIS. The modified Ag/NC/GO-GCE electrode was used as nanosensor for the electrocatalytic determination of nitrate using the voltammetric method. The effects of the parameters of scan rate, pH, and different nitrate concentrations were studied and the optimum conditions were obtained. A limit of detection of 0.016 µM (S/N=3 was found in the linear range of 0.005 to 10 mM nitrate. The Ag/NC/GO-GCE electrode exhibited a synergistic effect toward voltammetric determination of nitrate in the presence of graphene oxide, nanocellulose, and silver nanocatalyst. The nanosensor developed here showed excellent sensitivity, selectivity, and stability toward nitrate determination in aqueous solutions without any significant interference.

  14. A hybrid machine learning model to predict and visualize nitrate concentration throughout the Central Valley aquifer, California, USA

    Science.gov (United States)

    Ransom, Katherine M.; Nolan, Bernard T.; Traum, Jonathan A.; Faunt, Claudia; Bell, Andrew M.; Gronberg, Jo Ann M.; Wheeler, David C.; Zamora, Celia; Jurgens, Bryant; Schwarz, Gregory E.; Belitz, Kenneth; Eberts, Sandra; Kourakos, George; Harter, Thomas

    2017-01-01

    Intense demand for water in the Central Valley of California and related increases in groundwater nitrate concentration threaten the sustainability of the groundwater resource. To assess contamination risk in the region, we developed a hybrid, non-linear, machine learning model within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface. A database of 145 predictor variables representing well characteristics, historical and current field and landscape-scale nitrogen mass balances, historical and current land use, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The boosted regression tree (BRT) method was used to screen and rank variables to predict nitrate concentration at the depths of domestic and public well supplies. The novel approach included as predictor variables outputs from existing physically based models of the Central Valley. The top five most important predictor variables included two oxidation/reduction variables (probability of manganese concentration to exceed 50 ppb and probability of dissolved oxygen concentration to be below 0.5 ppm), field-scale adjusted unsaturated zone nitrogen input for the 1975 time period, average difference between precipitation and evapotranspiration during the years 1971–2000, and 1992 total landscape nitrogen input. Twenty-five variables were selected for the final model for log-transformed nitrate. In general, increasing probability of anoxic conditions and increasing precipitation relative to potential evapotranspiration had a corresponding decrease in nitrate concentration predictions. Conversely, increasing 1975 unsaturated zone nitrogen leaching flux and 1992 total landscape nitrogen input had an increasing relative

  15. Observations of fine particulate nitrated phenols in four sites in northern China: concentrations, source apportionment, and secondary formation

    Science.gov (United States)

    Wang, Liwei; Wang, Xinfeng; Gu, Rongrong; Wang, Hao; Yao, Lan; Wen, Liang; Zhu, Fanping; Wang, Weihao; Xue, Likun; Yang, Lingxiao; Lu, Keding; Chen, Jianmin; Wang, Tao; Zhang, Yuanghang; Wang, Wenxing

    2018-03-01

    Filter samples of fine particulate matters were collected at four sites in northern China (urban, rural, and mountain) in summer and winter, and the contents of nine nitrated phenols were quantified in the laboratory with the use of ultra-high-performance liquid chromatography coupled with mass spectrometry. During the sampling periods, the concentrations of particulate nitrated phenols exhibited distinct temporal and spatial variation. On average, the total concentration of particulate nitrated phenols in urban Jinan in the wintertime reached 48.4 ng m-3, and those in the summertime were 9.8, 5.7, 5.9, and 2.5 ng m-3 in urban Jinan, rural Yucheng and Wangdu, and Mt. Tai, respectively. The elevated concentrations of nitrated phenols in wintertime and in urban areas demonstrate the apparent influences of anthropogenic sources. The positive matrix factorization receptor model was then applied to determine the origins of particulate nitrated phenols in northern China. The five major source factors were traffic, coal combustion, biomass burning, secondary formation, and aged coal combustion plume. Among them, coal combustion played a vital role, especially at the urban site in the wintertime, with a contribution of around 55 %. In the summertime, the observed nitrated phenols were highly influenced by aged coal combustion plumes at all of the sampling sites. Meanwhile, in remote areas, contributions from secondary formation were significant. Further correlation analysis indicates that nitrosalicylic acids were produced mostly from secondary formation that was dominated by NO2 nitration.

  16. Effects of Unsaturated Microtopography on Nitrate Concentrations in Tundra Ecosystems: Examples from Polygonal Terrain and Degraded Peat Plateaus

    Science.gov (United States)

    Heikoop, J. M.; Arendt, C. A.; Newman, B. D.; Charsley-Groffman, L.; Perkins, G.; Wilson, C. J.; Wullschleger, S.

    2017-12-01

    Under the auspices of the Next Generation Ecosystem Experiment - Arctic, we have been studying hydrogeochemical signals in Alaskan tundra ecosystems underlain by continuous permafrost (Barrow Environmental Observatory (BEO)) and discontinuous permafrost (Seward Peninsula). The Barrow site comprises largely saturated tundra associated with the low gradient Arctic Coastal Plain. Polygonal microtopography, however, can result in slightly raised areas that are unsaturated. In these areas we have previously demonstrated production and accumulation of nitrate, which, based on nitrate isotopic analysis, derives from microbial degradation. Our Seward Peninsula site is located in a much steeper and generally well-drained watershed. In lower-gradient areas at the top and bottom of the watershed, however, the tundra is generally saturated, likely because of the presence of underlying discontinuous permafrost inhibiting infiltration. These settings also contain microtopographic features, though in the form of degraded peat plateaus surrounded by wet graminoid sag ponds. Despite being very different microtopographic features in a very different setting with distinct vegetation, qualitatively similar nitrate accumulation patterns as seen in polygonal terrain were observed. The highest nitrate pore water concentration observed in an unsaturated peat plateau was approximately 5 mg/L, whereas subsurface pore water concentrations in surrounding sag ponds were generally below the limit of detection. Nitrate isotopes indicate this nitrate results from microbial mineralization and nitrification based on comparison to the nitrate isotopic composition of reduced nitrogen sources in the environment and the oxygen isotope composition of site pore water. Nitrate concentrations were most similar to those found in low-center polygon rims and flat-centered polygon centers at the BEO, but were significantly lower than the maximum concentrations seen in the highest and driest polygonal features

  17. Uptake and accumulation of bulk and nanosized cerium oxide particles and ionic cerium by radish (Raphanus sativus L.).

    Science.gov (United States)

    Zhang, Weilan; Ebbs, Stephen D; Musante, Craig; White, Jason C; Gao, Cunmei; Ma, Xingmao

    2015-01-21

    The potential toxicity and accumulation of engineered nanomaterials (ENMs) in agricultural crops has become an area of great concern and intense investigation. Interestingly, although below-ground vegetables are most likely to accumulate the highest concentrations of ENMs, little work has been done investigating the potential uptake and accumulation of ENMs for this plant group. The overall objective of this study was to evaluate how different forms of cerium (bulk cerium oxide, cerium oxide nanoparticles, and the cerium ion) affected the growth of radish (Raphanus sativus L.) and accumulation of cerium in radish tissues. Ionic cerium (Ce(3+)) had a negative effect on radish growth at 10 mg CeCl3/L, whereas bulk cerium oxide (CeO2) enhanced plant biomass at the same concentration. Treatment with 10 mg/L cerium oxide nanoparticles (CeO2 NPs) had no significant effect on radish growth. Exposure to all forms of cerium resulted in the accumulation of this element in radish tissues, including the edible storage root. However, the accumulation patterns and their effect on plant growth and physiological processes varied with the characteristics of cerium. This study provides a critical frame of reference on the effects of CeO2 NPs versus their bulk and ionic counterparts on radish growth.

  18. Van Vleck temperature independent susceptibilities in the rare earth double nitrates

    International Nuclear Information System (INIS)

    Commander, R.J.; Finn, C.B.P.

    1978-01-01

    Measurements of the magnetic susceptibilities between 4.2 and 1.1 K of the rare earth zinc nitrates are reported. It is shown that the results for the Van Vleck temperature independent susceptibilities for cerium magnesium nitrate and cerium zinc nitrate are consistent with the published low lying level schemes for these two salts. (author)

  19. Nitrogen concentrations in a small Mediterranean stream: 1. Nitrate 2. Ammonium

    Directory of Open Access Journals (Sweden)

    A. Butturini

    2002-01-01

    Full Text Available The importance of storm frequency as well as the groundwater and hyporheic inputs on nitrate (NO3-N and ammonium (NH4-N levels in stream water were studied in a small perennial Mediterranean catchment, Riera Major, in northeast Spain. NO3-N concentrations ranged from 0.15 to 1.9 mg l-1. Discharge explained 47% of the annual NO3-N concentration variance, but this percentage increased to 97% when single floods were analysed. The rate of change in nitrate concentration with respect to flow, ΔNO3-N/ΔQ, ranged widely from 0 to 20 μg NO3-N s l-2. The ΔNO3-N/ΔQ values fitted to a non linear model with respect to the storm flow magnitude (ΔQ (r2=0.48, d.f.=22, P3-N/ΔQ occurred at intermediate ΔQ values, whereas low ΔNO3-N/ΔQ values occurred during severe storms (ΔQ > 400 l s-1. N3-N concentrations exhibit anticlockwise hysteresis patterns with changing flow and the patterns observed for autumnal and winter storms indicated that groundwater was the main N3-N source for stream and hyporheic water. At baseflow, NO3-N concentration in groundwater was higher (t=4.75, d.f.=29, P>0.001 and co-varied with concentrations in the stream (r=0.91, d.f.=28, P3-N concentration in hyporheic water was identical to that in stream water. The role of the hyporheic zone as source or sink for ammonium was studied hyporheic was studied comparing its concentrations in stream and hyporheic zone before and after a major storm occurred in October 1994 that removed particulate organic matter stored in sediments. Results showed high ammonium concentrations (75±28 s.d. μg NH4-N l-1 before the storm flow in the hyporheic zone. After the storm, the ammonium concentration in the hyporheic dropped by 80% (13.6±8 μg N4-N l-1 and approached to the level found in stream water (11±8 μg NH4-N l-1 indicating that indisturbed hyporheic sediments act as a source for ammonium. After the storm, the ammonium concentrations in the stream, hyporheic and groundwater zones were very

  20. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  1. Effect of uranyl nitrate and free acid concentration in feed solution of gelation on UO2 kernel quality

    International Nuclear Information System (INIS)

    Masduki, B.; Wardaya; Widarmoko, A.

    1996-01-01

    An investigation on the effect of uranium and free nitric acid concentration of uranyl nitrate as feed of gelation process on quality of UO 2 kernel was done.The investigation is to look for some concentration of uranyl nitrate solutions those are optimum as feed for preparation of gelled UO 3 . Uranyl nitrate solution of various concentration of uranium (450; 500; 550; 600; 650; 700 g/l) and free nitric acid of (0.9; 1.0; 1.1 N) was made into feed solutions by adding urea and HMTA with mole ratio of urea/uranium and HMTA/uranium 2.1 and 2.0. The feed solutions were changed into spherical gelled UO 3 by dropping was done to get the optimum concentrations of uranyl nitrate solutions. The gelled UO 3 was soaked and washed with 2.5% ammonia solution for 17 hours, dried at 70 o C, calcined at 350 o C for 3 hours then reduced at 850 o C for 3 hours. At every step of the steps process the colour and percentage of well product of gelled UO 3 were noticed. The density and O/U ratio of end product (UO 2 kernel) was determined, the percentage of well product of all steps process was also determined. The three factor were used to chose the optimum concentration of uranyl nitrate solution. From this investigation it was concluded that the optimum concentration of uranyl nitrate was 600 g/l uranium with free nitric acid 0,9 - 1,0 N, the percentage of well product was 97% density of 6.12 - 4.8 g/cc and O/U ratio of 2.15 - 2.06. (author)

  2. Adsorption of Some Hazardous Radionuclides on Cerium(IV) Antimonate

    International Nuclear Information System (INIS)

    Aly, H.F.; Zakaria, E.S.; Shady, S.A.; El-Naggar, I.M.

    1999-01-01

    Cerium(IV) antimonate had been prepared by the dropwise addition of 0.6 M antimony pentachloride and 0.6 M cerium ammonium nitrate solutions by a molar radio of Ce/Sb 0.75. Exchange isotherms for H +/ Co 2+ , H +/ Cs +, H +/ Zn 2+ , H +/ Sr 2+ and H +/ Eu 3+ have been determined at 25, 40 and 60 degree. Besides it was proved that europium is physically adsorbed while zinc, strontium, cobalt and cesium are chemically adsorbed. Moreover, the heat of adsorption of zinc, strontium, cobalt and cesium on cerium(IV) antimonate had been calculated and indicated that cerium(IV) antimonate is of endothermic behaviour towards these ions. Also the distribution coefficients of these ions were determined and it was found that the selectivity in the order: Eu 3+ >Sr 2+ > Cs +> Na +

  3. Molecular toxicity of cerium oxide nanoparticles to the freshwater alga Chlamydomonas reinhardtii is associated with supra-environmental exposure concentrations

    Science.gov (United States)

    Taylor, Nadine S.; Merrifield, Ruth; Williams, Tim D.; Chipman, J. Kevin; Lead, Jamie R.; Viant, Mark R.

    2016-01-01

    Abstract Ceria nanoparticles (NPs) are widely used as fuel catalysts and consequently are likely to enter the environment. Their potential impacts on. biota at environmentally relevant concentrations, including uptake and toxicity, remain to be elucidated and quantitative data on which to assess risk are sparse. Therefore, a definitive assessment of the molecular and phenotypic effects of ceria NPs was undertaken, using well-characterised mono-dispersed NPs as their toxicity is likely to be higher, enabling a conservative hazard assessment. Unbiased transcriptomics and metabolomics approaches were used to investigate the potential toxicity of tightly constrained 4–5 nm ceria NPs to the unicellular green alga, Chlamydomonas reinhardtii, a sentinel freshwater species. A wide range of exposure concentrations were investigated from predicted environmental levels, to support hazard assessment, to supra-environmental levels to provide insight into molecular toxicity pathways. Ceria NPs were internalised into intracellular vesicles within C. reinhardtii, yet caused no significant effect on algal growth at any exposure concentration. Molecular perturbations were only detected at supra-environmental ceria NP-concentrations, primarily down-regulation of photosynthesis and carbon fixation with associated effects on energy metabolism. For acute exposures to small mono-dispersed particles, it can be concluded there should be little concern regarding their dispersal into the environment for this trophic level. PMID:25740379

  4. Observations of fine particulate nitrated phenols in four sites in northern China: concentrations, source apportionment, and secondary formation

    Directory of Open Access Journals (Sweden)

    L. Wang

    2018-03-01

    Full Text Available Filter samples of fine particulate matters were collected at four sites in northern China (urban, rural, and mountain in summer and winter, and the contents of nine nitrated phenols were quantified in the laboratory with the use of ultra-high-performance liquid chromatography coupled with mass spectrometry. During the sampling periods, the concentrations of particulate nitrated phenols exhibited distinct temporal and spatial variation. On average, the total concentration of particulate nitrated phenols in urban Jinan in the wintertime reached 48.4 ng m−3, and those in the summertime were 9.8, 5.7, 5.9, and 2.5 ng m−3 in urban Jinan, rural Yucheng and Wangdu, and Mt. Tai, respectively. The elevated concentrations of nitrated phenols in wintertime and in urban areas demonstrate the apparent influences of anthropogenic sources. The positive matrix factorization receptor model was then applied to determine the origins of particulate nitrated phenols in northern China. The five major source factors were traffic, coal combustion, biomass burning, secondary formation, and aged coal combustion plume. Among them, coal combustion played a vital role, especially at the urban site in the wintertime, with a contribution of around 55 %. In the summertime, the observed nitrated phenols were highly influenced by aged coal combustion plumes at all of the sampling sites. Meanwhile, in remote areas, contributions from secondary formation were significant. Further correlation analysis indicates that nitrosalicylic acids were produced mostly from secondary formation that was dominated by NO2 nitration.

  5. Concentrations of nitrate in drinking water in the lower Yakima River Basin, Groundwater Management Area, Yakima County, Washington, 2017

    Science.gov (United States)

    Huffman, Raegan L.

    2018-05-29

    The U.S. Geological Survey, in cooperation with the lower Yakima River Basin Groundwater Management Area (GWMA) group, conducted an intensive groundwater sampling collection effort of collecting nitrate concentration data in drinking water to provide a baseline for future nitrate assessments within the GWMA. About every 6 weeks from April through December 2017, a total of 1,059 samples were collected from 156 wells and 24 surface-water drains. The domestic wells were selected based on known location, completion depth, ability to collect a sample prior to treatment on filtration, and distribution across the GWMA. The drains were pre-selected by the GWMA group, and further assessed based on ability to access sites and obtain a representative sample. More than 20 percent of samples from the domestic wells and 12.8 percent of drain samples had nitrate concentrations that exceeded the maximum contaminant level (MCL) of 10 milligrams per liter established by the U.S. Environmental Protection Agency. At least one nitrate concentration above the MCL was detected in 26 percent of wells and 33 percent of drains sampled. Nitrate was not detected in 13 percent of all samples collected.

  6. Raman spectroscopic study of the aging and nitration of actinide processing anion-exchange resins in concentrated nitric acid

    International Nuclear Information System (INIS)

    Buscher, C. T.; Donohoe, R. J.; Mecklenburg, S. L.; Berg, J. M.; Tait, C. D.; Huchton, K. M.; Morris, D. E.

    1999-01-01

    Degradation of two types of anion exchange resins, Dowex 11 and Reillex HPQ, from the action of concentrated nitric acid (4 to 12 M) and radiolysis [from depleted uranium as UO 2 2+ nitrate species and 239 Pu as Pu(IV) nitrate species] was followed as a function of time with Raman vibrational spectroscopy. Elevated temperatures (∼50 degree sign C) were used in the absence of actinide metal loading to simulate longer exposures of the resin to a HNO 3 process stream and waste storage conditions. In the absence of actinide loading, only minor changes in the Dowex resin at acid concentrations ≤10 M were observed, while at 12 M acid concentration, the emergence of a Raman peak at 1345 cm-1 indicates the addition of nitro functional groups to the resin. Similar studies with the Reillex resin show it to be more resistant to nitric acid attack at all acid concentrations. Incorporation of weakly radioactive depleted uranium as the UO 2 2+ nitrate species to the ion-exchange sites of Dowex 11 under differing nitric acid concentrations (6 to 12 M) at room temperature showed no Raman evidence of resin degradation or nitration, even after several hundred days of contact. In contrast, Raman spectra for Dowex 11 in the presence of 239 Pu as Pu(IV) nitrate species reveal numerous changes indicating resin alterations, including a new mode at 1345 cm-1 consistent with a Pu(IV)-nitrate catalyzed addition of nitro groups to the resin backbone. (c) 2000 Society for Applied Spectroscopy

  7. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    International Nuclear Information System (INIS)

    Shih, C.J.; Chen, Y.J.; Hon, M.H.

    2010-01-01

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol -1 .

  8. Synthesis and crystal kinetics of cerium oxide nanocrystallites prepared by co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Shih, C.J., E-mail: cjshih@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Chen, Y.J. [Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hon, M.H. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2010-05-15

    Cerium oxide nanocrystallites were synthesized at a relatively low temperature using cerium nitrate as starting materials in a water solution by a co-precipitation process. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K by XRD analysis. When calcined from 473 to 1273 K, the crystallization of the face-centered cubic phase was observed by XRD. The crystallite size of the cerium oxide increased from 10.0 to 43.8 nm with calcining temperature increasing from 673 to 1273 K. The activation energy for growth of cerium oxide nanoparticles was found to be 16.0 kJ mol{sup -1}.

  9. Berkelium (4) and cerium (4) extraction with tertiary amines

    International Nuclear Information System (INIS)

    Milyukova, M.S.; Malikov, D.A.; Myasoedov, B.V.

    1978-01-01

    Oxidation of indicator quantities of berkelium and cerium by a mixture of silver nitrate and ammonium persulfate in the solutions of nitric and sulfuric acid has been examined. The stability of the elements in a tetravalent state and their extraction by the solutions of ternary amines have been investigated. It has been established that berkelium and cerium oxidation under these conditions occurs under the effect of ions of divalent silver which is formed owing to oxidation of monovalent silver by peroxide sulfate ions. The following supposition has been put forward: a difference in the behaviour of tetravalent berkelium and cerium during their extraction by ternary amines is explained by their different stability in this state, but not by the formation of complex compounds with nitrate ions

  10. A GIS-based groundwater travel time model to evaluate stream nitrate concentration reductions from land use change

    Science.gov (United States)

    Schilling, K.E.; Wolter, C.F.

    2007-01-01

    Excessive nitrate-nitrogen (nitrate) loss from agricultural watersheds is an environmental concern. A common conservation practice to improve stream water quality is to retire vulnerable row croplands to grass. In this paper, a groundwater travel time model based on a geographic information system (GIS) analysis of readily available soil and topographic variables was used to evaluate the time needed to observe stream nitrate concentration reductions from conversion of row crop land to native prairie in Walnut Creek watershed, Iowa. Average linear groundwater velocity in 5-m cells was estimated by overlaying GIS layers of soil permeability, land slope (surrogates for hydraulic conductivity and gradient, respectively) and porosity. Cells were summed backwards from the stream network to watershed divide to develop a travel time distribution map. Results suggested that groundwater from half of the land planted in prairie has reached the stream network during the 10 years of ongoing water quality monitoring. The mean travel time for the watershed was estimated to be 10.1 years, consistent with results from a simple analytical model. The proportion of land in the watershed and subbasins with prairie groundwater reaching the stream (10-22%) was similar to the measured reduction of stream nitrate (11-36%). Results provide encouragement that additional nitrate reductions in Walnut Creek are probable in the future as reduced nitrate groundwater from distal locations discharges to the stream network in the coming years. The high spatial resolution of the model (5-m cells) and its simplicity may make it potentially applicable for land managers interested in communicating lag time issues to the public, particularly related to nitrate concentration reductions over time. ?? 2007 Springer-Verlag.

  11. Cerium oxalate precipitation

    International Nuclear Information System (INIS)

    Chang, T.P.

    1987-02-01

    Cerium, a nonradioactive, common stand-in for plutonium in development work, has been used to simulate several plutonium precipitation processes at the Savannah River Laboratory. There are similarities between the plutonium trifluoride and the cerium oxalate precipitations in particle size and extent of plating, but not particle morphology. The equilibrium solubility, precipitation kinetics, particle size, extent of plating, and dissolution characteristics of cerium oxalate have been investigated. Interpretations of particle size and plating based on precipitation kinetics (i.e., nucleation and crystal growth) are presented. 16 refs., 7 figs., 6 tabs

  12. Concentration of a sodium nitrate-based waste with a wiped film evaporation

    International Nuclear Information System (INIS)

    Farr, L.L.; Boring, M.D.; Fowler, V.L.; Hewitt, J.D.

    1995-01-01

    Oak Ridge National Laboratory (ORNL) currently has an inventory of 500,000 gallons of sodium nitrate-based radioactive liquid waste which is currently stored in the Melton Valley Storage Tanks (MVST). This waste needs to be treated and one option being considered is concentration of the wastes using evaporation. Testing is underway to determine whether a Wiped Film Evaporator (WFE) can be used to concentrate these wastes in an economical and reliable manner. The capability of the evaporator to process a non-radioactive simulant of the MVST wastes over a range of operating conditions is being studied. The equipment has to be checked for reliability, potential corrosion problems, and the effects of the waste on the efficiency of heat transfer due to scaling. Physical and chemical characteristics of the product and distillate are being investigated. Heat transfer coefficients and volume reductions are being determined under different operating conditions. Decontamination factors are being calculated to determine the necessity for further treatment of the distillate and off-gas

  13. Maps of estimated nitrate and arsenic concentrations in basin-fill aquifers of the southwestern United States

    Science.gov (United States)

    Beisner, Kimberly R.; Anning, David W.; Paul, Angela P.; McKinney, Tim S.; Huntington, Jena M.; Bexfield, Laura M.; Thiros, Susan A.

    2012-01-01

    Human-health concerns and economic considerations associated with meeting drinking-water standards motivated a study of the vulnerability of basin-fill aquifers to nitrate contamination and arsenic enrichment in the southwestern United States. Statistical models were developed by using the random forest classifier algorithm to predict concentrations of nitrate and arsenic across a model grid representing about 190,600 square miles of basin-fill aquifers in parts of Arizona, California, Colorado, Nevada, New Mexico, and Utah. The statistical models, referred to as classifiers, reflect natural and human-related factors that affect aquifer vulnerability to contamination and relate nitrate and arsenic concentrations to explanatory variables representing local- and basin-scale measures of source and aquifer susceptibility conditions. Geochemical variables were not used in concentration predictions because they were not available for the entire study area. The models were calibrated to assess model accuracy on the basis of measured values.Only 2 percent of the area underlain by basin-fill aquifers in the study area was predicted to equal or exceed the U.S. Environmental Protection Agency drinking-water standard for nitrate as N (10 milligrams per liter), whereas 43 percent of the area was predicted to equal or exceed the standard for arsenic (10 micrograms per liter). Areas predicted to equal or exceed the drinking-water standard for nitrate include basins in central Arizona near Phoenix; the San Joaquin Valley, the Santa Ana Inland, and San Jacinto Basins of California; and the San Luis Valley of Colorado. Much of the area predicted to equal or exceed the drinking-water standard for arsenic is within a belt of basins along the western portion of the Basin and Range Physiographic Province that includes almost all of Nevada and parts of California and Arizona. Predicted nitrate and arsenic concentrations are substantially lower than the drinking-water standards in much of

  14. Relations that affect the probability and prediction of nitrate concentration in private wells in the glacial aquifer system in the United States

    Science.gov (United States)

    Warner, Kelly L.; Arnold, Terri L.

    2010-01-01

    Nitrate in private wells in the glacial aquifer system is a concern for an estimated 17 million people using private wells because of the proximity of many private wells to nitrogen sources. Yet, less than 5 percent of private wells sampled in this study contained nitrate in concentrations that exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 mg/L (milligrams per liter) as N (nitrogen). However, this small group with nitrate concentrations above the USEPA MCL includes some of the highest nitrate concentrations detected in groundwater from private wells (77 mg/L). Median nitrate concentration measured in groundwater from private wells in the glacial aquifer system (0.11 mg/L as N) is lower than that in water from other unconsolidated aquifers and is not strongly related to surface sources of nitrate. Background concentration of nitrate is less than 1 mg/L as N. Although overall nitrate concentration in private wells was low relative to the MCL, concentrations were highly variable over short distances and at various depths below land surface. Groundwater from wells in the glacial aquifer system at all depths was a mixture of old and young water. Oxidation and reduction potential changes with depth and groundwater age were important influences on nitrate concentrations in private wells. A series of 10 logistic regression models was developed to estimate the probability of nitrate concentration above various thresholds. The threshold concentration (1 to 10 mg/L) affected the number of variables in the model. Fewer explanatory variables are needed to predict nitrate at higher threshold concentrations. The variables that were identified as significant predictors for nitrate concentration above 4 mg/L as N included well characteristics such as open-interval diameter, open-interval length, and depth to top of open interval. Environmental variables in the models were mean percent silt in soil, soil type, and mean depth to

  15. Establishing a Multi-spatial Wireless Sensor Network to Monitor Nitrate Concentrations in Soil Moisture

    Science.gov (United States)

    Haux, E.; Busek, N.; Park, Y.; Estrin, D.; Harmon, T. C.

    2004-12-01

    The use of reclaimed wastewater for irrigation in agriculture can be a significant source of nutrients, in particular nitrogen species, but its use raises concern for groundwater, riparian, and water quality. A 'smart' technology would have the ability to measure wastewater nutrients as they enter the irrigation system, monitor their transport in situ and optimally control inputs with little human intervention, all in real-time. Soil heterogeneity and economic issues require, however, a balance between cost and the spatial and temporal scales of the monitoring effort. Therefore, a wireless and embedded sensor network, deployed in the soil vertically across the horizon, is capable of collecting, processing, and transmitting sensor data. The network consists of several networked nodes or 'pylons', each outfitted with an array of sensors measuring humidity, temperature, precipitation, soil moisture, and aqueous nitrate concentrations. Individual sensor arrays are controlled by a MICA2 mote (Crossbow Technology Inc., San Jose, CA) programmed with TinyOS (University of California, Berkeley, CA) and a Stargate (Crossbow Technology Inc., San Jose, CA) base-station capable of GPRS for data transmission. Results are reported for the construction and testing of a prototypical pylon at the benchtop and in the field.

  16. Effect of growing plants on denitrification at high soil nitrate concentrations

    International Nuclear Information System (INIS)

    Haider, K.; Mosier, A.; Heinemeyer, O.

    1987-01-01

    The availability of plant rhizosphere C deposits and its influence on microbial denitrification is not clearly defined. Conflicting reports as to the influence of plants and root exudation on denitrification continue to appear in the literature. The results of the authors earlier phytotron study indicated that denitrification was not stimulated in soils planted with corn or wheat compared to unplanted soils. Lower nitrate concentrations in the planted soils, however, may have led to misinterpretation of this data. A second study was conducted, to evaluate the effect of actively growing plants on denitrification where the NO 3 7 content of planted soils was maintained similar to unplanted soils. Simultaneously the C fixed by corn (Zea mays) and the fate of fertilizer N applied to the soil during the growing season were quantified. The corn was grown in a phytotron under a continuous supply of 14 CO 2 in 15 N fertilized soils to which 15 N-NO 3 - was added periodically during the growing season. The results of these studies showed that denitrification was not stimulated in soils planted with corn during active plant growth phase even when soil NO 3 - was relatively high. Denitrification was, however, greater in corn planted than unplanted soil when the recoverable root biomass began to decrease. Less N was immobilized and net 15 N immobilization was lower in planted soils than in unplanted soils. As denitrification was lower in planted soils during the time of active plant growth, the study suggests that root exudates did not stimulate either process

  17. Nitrate concentration-drainage flow (C-Q) relationship for a drained agricultural field in Eastern North Carolina Plain

    Science.gov (United States)

    Liu, W.; Youssef, M.; Birgand, F.; Chescheir, G. M.; Maxwell, B.; Tian, S.

    2017-12-01

    Agricultural drainage is a practice used to artificially enhance drainage characteristics of naturally poorly drained soils via subsurface drain tubing or open-ditch systems. Approximately 25% of the U.S. agricultural land requires improved drainage for economic crop production. However, drainage increases the transport of dissolved agricultural chemicals, particularly nitrates to downstream surface waters. Nutrient export from artificially drained agricultural landscapes has been identified as the leading source of elevated nutrient levels in major surface water bodies in the U.S. Controlled drainage has long been practiced to reduce nitrogen export from agricultural fields to downstream receiving waters. It has been hypothesized that controlled drainage reduces nitrogen losses by promoting denitrification, reducing drainage outflow from the field, and increasing plant uptake. The documented performance of the practice was widely variable as it depends on several site-specific factors. The goal of this research was to utilize high frequency measurements to investigate the effect of agricultural drainage and related management practices on nitrate fate and transport for an artificially drained agricultural field in eastern North Carolina. We deployed a field spectrophotometer to measure nitrate concentration every 45 minutes and measured drainage flow rate using a V-notch weir every 15 minutes. Furthermore, we measured groundwater level, precipitation, irrigation amount, temperature to characterize antecedent conditions for each event. Nitrate concentration-drainage flow (C-Q) relationships generated from the high frequency measurements illustrated anti-clockwise hysteresis loops and nitrate flushing mechanism in response to most precipitation and irrigation events. Statistical evaluation will be carried out for the C-Q relationships. The results of our analysis, combined with numerical modeling, will provide a better understanding of hydrological and

  18. Temporal trends in concentrations of DBCP and nitrate in groundwater in the eastern San Joaquin Valley, California, USA

    Science.gov (United States)

    Burow, K.R.; Dubrovsky, N.M.; Shelton, James L.

    2007-01-01

    Temporal monitoring of the pesticide 1,2-dibromo-3-chloropropane (DBCP) and nitrate and indicators of mean groundwater age were used to evaluate the transport and fate of agricultural chemicals in groundwater and to predict the long-term effects in the regional aquifer system in the eastern San Joaquin Valley, California. Twenty monitoring wells were installed on a transect along an approximate groundwater flow path. Concentrations of DBCP and nitrate in the wells were compared to concentrations in regional areal monitoring networks. DBCP persists at concentrations above the US Environmental Protection Agency's maximum contaminant level (MCL) at depths of nearly 40 m below the water table, more than 25 years after it was banned. Nitrate concentrations above the MCL reached depths of more than 20 m below the water table. Because of the intensive pumping and irrigation recharge, vertical flow paths are dominant. High concentrations (above MCLs) in the shallow part of the regional aquifer system will likely move deeper in the system, affecting both domestic and public-supply wells. The large fraction of old water (unaffected by agricultural chemicals) in deep monitoring wells suggests that it could take decades for concentrations to reach MCLs in deep, long-screened public-supply wells, however. ?? Springer-Verlag 2007.

  19. [Assessment of shallow groundwater nitrate concentrations in typical terrestrial ecosystems of Chinese Ecosystem Research Network (CERN) during 2004-2009].

    Science.gov (United States)

    Xu, Zhi-Wei; Zhang, Xin-Yu; Sun, Xiao-Min; Yuan, Guo-Fu; Wang, Sheng-Zhong; Liu, Wen-Hua

    2011-10-01

    The nitrate-N (NO3(-) -N) concentrations of 38 shallow groundwater wells from 31 of the typical terrestrial ecosystems on Chinese Ecosystem Research Network (CERN) were assessed using the monitoring data from 2004 to 2009. The results showed that the average values of NO3(-) -N concentrations were significantly higher in the agricultural (4.85 mg x L(-1) +/- 0.42 mg x L(-1)), desert (oasis) (3.72 mg x L(-1) +/- 0.42 mg x L(-1)) and urban ecosystems (3.77 mg x L(-1) 0.51 mg x L(-1)) than in the grass (1.59 mg x L(-1) +/- 0.35 mg L(-1)) and forest ecosystems (0.39 mg x L(-1) +/- 0.03 mg x L(-1)). Nitrate was the major form of nitrogen, with between 56% to 88% of nitrogen in the nitrate-N form in the shallow groundwater of desert (oasis), urban and agricultural ecosystems. Nitrate-N concentrations for some agricultural ecosystems (Ansai, Yanting, Yucheng) and desert (oasis) ecosystems (Cele, Linze, Akesu) analysis exceeded the 10 mg x L(-1) World Health Organization drinking water standards between 14.3% and 84.6%. Significant seasonality was found in Ansai, Fengqiu, Yanting agricultural ecosystems and the Beijing urban ecosystem using the relatively high frequency monitoring data, with the higher nitrate concentrations usually found during summer and winter months. The monitoring results indicated that the shallow groundwater of agricultural ecosystems was contaminated by agricultural management practices, i.e. fertilization, while the shallow groundwater of forest ecosystems was under natural condition with no contamination from human activities.

  20. Spatial and temporal changes in the structure of groundwater nitrate concentration time series (1935 1999) as demonstrated by autoregressive modelling

    Science.gov (United States)

    Jones, A. L.; Smart, P. L.

    2005-08-01

    Autoregressive modelling is used to investigate the internal structure of long-term (1935-1999) records of nitrate concentration for five karst springs in the Mendip Hills. There is a significant short term (1-2 months) positive autocorrelation at three of the five springs due to the availability of sufficient nitrate within the soil store to maintain concentrations in winter recharge for several months. The absence of short term (1-2 months) positive autocorrelation in the other two springs is due to the marked contrast in land use between the limestone and swallet parts of the catchment, rapid concentrated recharge from the latter causing short term switching in the dominant water source at the spring and thus fluctuating nitrate concentrations. Significant negative autocorrelation is evident at lags varying from 4 to 7 months through to 14-22 months for individual springs, with positive autocorrelation at 19-20 months at one site. This variable timing is explained by moderation of the exhaustion effect in the soil by groundwater storage, which gives longer residence times in large catchments and those with a dominance of diffuse flow. The lags derived from autoregressive modelling may therefore provide an indication of average groundwater residence times. Significant differences in the structure of the autocorrelation function for successive 10-year periods are evident at Cheddar Spring, and are explained by the effect the ploughing up of grasslands during the Second World War and increased fertiliser usage on available nitrogen in the soil store. This effect is moderated by the influence of summer temperatures on rates of mineralization, and of both summer and winter rainfall on the timing and magnitude of nitrate leaching. The pattern of nitrate leaching also appears to have been perturbed by the 1976 drought.

  1. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

    Science.gov (United States)

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-01-01

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1), Ce (1.492 ± 0.995 μg∙L−1), Nd (0.014 ± 0.009 μg∙L−1) and Gd (0.023 ± 0.010 μg∙L−1) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend

  2. Local Structure of Cerium in Aluminophosphate and Silicophosphate Glasses

    International Nuclear Information System (INIS)

    Rygel, Jennifer L.; Chen, Yongsheng; Pantano, Carlo G.; Shibata, Tomohiro; Du, Jincheng; Kokou, Leopold; Woodman, Robert; Belcher, James

    2011-01-01

    The local structure of cerium in two systematic compositional series of glasses, nominally CeP 3 O 9 -AlP 3 O 9 and CeP 3 O 9 -SiP 2 O 7 , was interrogated using X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy. XPS revealed that, for glasses melted in air, ≥95% of cerium ions are Ce 3+ . This was independently confirmed using X-ray absorption near edge spectroscopy (XANES). Ce K-edge extended X-ray absorption fine structure (EXAFS) has been used to determine the local structure of Ce 3+ . Near the metaphosphate composition, cerium was found to have an average cerium coordination number of ∼7.0 and an average cerium-oxygen bond length of 2.41 (angstrom). The average cerium coordination number and average cerium-oxygen bond distance were found to increase with decreasing cerium concentration in both compositional series. Rare-earth clustering is suggested based on numerical calculations for glasses containing ≥14 and ≥15 mol% Ce 2 O 3 for the aluminophosphate and silicophosphate series, respectively.

  3. A method for the gravimetric determination of plutonium in pure plutonium nitrate concentrate solution

    International Nuclear Information System (INIS)

    Mair, M.A.; Savage, D.J.

    1986-12-01

    Plutonium nitrate solution is treated with sulphuric acid before being heated and finally ignited. The stoichiometric plutonium dioxide so formed is weighed and hence the plutonium content is calculated. (author)

  4. Patterns of Diel Variation in Nitrate Concentrations in the Potomac River

    Science.gov (United States)

    Burns, D. A.; Miller, M. P.; Pellerin, B. A.; Capel, P. D.

    2015-12-01

    The Potomac River is the second largest source of nitrogen to Chesapeake Bay, where reducing nutrient loads has been a focus of efforts to improve estuarine trophic status. Two years of high frequency sensor measurements of nitrate (NO3-) concentrations in the Upper Potomac River at the Little Falls gage were analyzed to quantify seasonal variation in the magnitude and timing of the apparent loss of NO3- from the water column that results from diel-driven processes. In addition to broad seasonal and flow-driven variation in NO3- concentrations, clear diel patterns were evident in the river, especially during low flow conditions that follow stormflow by several days. Diel variation was about 0.01 mg N/L in winter and 0.02 to 0.03 mg N/L in summer with intermediate values during spring and fall. This variation was equivalent to 10% occurred during some summer days. Maximum diel concentrations occurred during mid- to late-morning in most seasons, with the most repeatable patterns in summer and wider variation in timing during fall and winter. Diel NO3- loss diminished loads by about 0.6% in winter and 1.3% in summer, and diel-driven processes were minor compared to estimates of total in-stream NO3- loss that averaged about one-third of the inferred groundwater NO3- contribution to the river network. The magnitude of diel NO3- variation was more strongly related to metrics based on water temperature and discharge than to metrics based on photosynthetically active radiation. Despite the fairly low diminishment of NO3- loads attributable to diel variation, estimates of diel NO3- uptake were fairly high compared to published values from smaller streams and rivers. The diel NO3- patterns observed in the Potomac River are consistent with photosynthesis of periphyton as a principal driver which may be linked to denitrification through the release of labile carbon. The extent to which these diel patterns are related to measures of aquatic metabolism are unknown as is the role

  5. Stream Nitrate Concentrations Diverge at Baseflow and Converge During Storms in Watersheds with Contrasting Urbanization

    Science.gov (United States)

    Carey, R. O.; Wollheim, W. M.; Mulukutla, G. K.; Cook, C. S.

    2013-12-01

    Management of non-point sources is challenging because it requires adequate quantification of non-point fluxes that are highly dynamic over time. Most fluxes occur during storms and are difficult to characterize with grab samples alone in flashy, urban watersheds. Accurate and relatively precise measurements using in situ sensor technology can quantify fluxes continuously, avoiding the uncertainties in extrapolation of infrequently collected grab samples. In situ nitrate (NO3-N) sensors were deployed simultaneously from April to December 2013 in two streams with contrasting urban land uses in an urbanizing New Hampshire watershed (80 km2). Nitrogen non-point fluxes and temporal patterns were evaluated in Beards Creek (forested: 50%; residential: 24%; commercial/institutional/transportation: 7%; agricultural: 6%) and College Brook (forested: 35%; residential: 11%; commercial/institutional/transportation: 20%; agricultural: 17%). Preliminary data indicated NO3-N concentrations in Beards Creek (mean: 0.37 mg/L) were lower than College Brook (mean: 0.60 mg/L), but both streams exhibited rapid increases in NO3-N during the beginning of storms followed by overall dilution. While baseflow NO3-N was greater in College Brook than Beards Creek, NO3-N at the two sites consistently converged during storms. This suggests that standard grab sampling may overestimate fluxes in urban streams, since short-term dilution occurred during periods of highest flow. Analyzing NO3-N flux patterns in smaller urban streams that are directly impacted by watershed activities could help to inform management decisions regarding N source controls, ultimately allowing an assessment of the interactions of climate variability and management actions.

  6. Nitrous oxide and nitrate concentration in under-drainage from arable fields subject to diffuse pollution mitigation measures

    Science.gov (United States)

    Hama-Aziz, Zanist; Hiscock, Kevin; Adams, Christopher; Reid, Brian

    2016-04-01

    Atmospheric nitrous oxide concentrations are increasing by 0.3% annually and a major source of this greenhouse gas is agriculture. Indirect emissions of nitrous oxide (e.g. from groundwater and surface water) account for about quarter of total nitrous oxide emissions. However, these indirect emissions are subject to uncertainty, mainly due to the range in reported emission factors. It's hypothesised in this study that cover cropping and implementing reduced (direct drill) cultivation in intensive arable systems will reduce dissolved nitrate concentration and subsequently indirect nitrous oxide emissions. To test the hypothesis, seven fields with a total area of 102 ha in the Wensum catchment in eastern England have been chosen for experimentation together with two fields (41 ha) under conventional cultivation (deep inversion ploughing) for comparison. Water samples from field under-drainage have been collected for nitrate and nitrous oxide measurement on a weekly basis from April 2013 for two years from both cultivation areas. A purge and trap preparation line connected to a Shimadzu GC-8A gas chromatograph fitted with an electron capture detector was used for dissolved nitrous oxide analysis. Results revealed that with an oilseed radish cover crop present, the mean concentration of nitrate, which is the predominant form of N, was significantly depleted from 13.9 mg N L-1 to 2.5 mg N L-1. However, slightly higher mean nitrous oxide concentrations under the cover crop of 2.61 μg N L-1 compared to bare fields of 2.23 μg N L-1 were observed. Different inversion intensity of soil tended to have no effect on nitrous oxide and nitrate concentrations. The predominant production mechanism for nitrous oxide was nitrification process and the significant reduction of nitrate was due to plant uptake rather than denitrification. It is concluded that although cover cropping might cause a slight increase of indirect nitrous oxide emission, it can be a highly effective

  7. A data mining approach to improve multiple regression models of soil nitrate concentration predictions in Quercus rotundifolia montados (Portugal)

    OpenAIRE

    Nunes, Jorge; Madeira, Manuel; Gazarini, Luiz; Neves, José; Vicente, Henrique

    2012-01-01

    The changes in the soil nitrate concentration were studied during 2 years in a ‘‘montado’’ ecosystem, in the South of Portugal. Total rainfall, air and soil temperature and soil water content under and outside Quercus rotundifolia canopy were also evaluated. A cluster analysis was carried out using climatic and microclimatic parameters in order to maximize the intraclass similarity and minimize the interclass similarity. It was used the k-Means Clustering Method. Se...

  8. Determination of endogenous concentrations of nitrites and nitrates in different types of cheese in the United States: method development and validation using ion chromatography.

    Science.gov (United States)

    Genualdi, Susan; Jeong, Nahyun; DeJager, Lowri

    2018-04-01

    Nitrites and nitrates can be present in dairy products from both endogenous and exogenous sources. In the European Union (EU), 150 mg kg - 1 of nitrates are allowed to be added to the cheese milk during the manufacturing process. The CODEX General Standard for Food Additives has a maximum permitted level of 50 mg kg - 1 residue in cheese, while in the United States (U.S.) nitrates are unapproved for use as food additives in cheese. In order to be able to investigate imported cheeses for nitrates intentionally added as preservatives and the endogenous concentrations of nitrates and nitrites present in cheeses in the U.S. marketplace, a method was developed and validated using ion chromatography with conductivity detection. A market sampling of cheese samples purchased in the Washington DC metro area was performed. In 64 samples of cheese, concentrations ranged from below the method detection limit (MDL) to 26 mg kg - 1 for nitrates and no concentrations of nitrites were found in any of the cheese samples above the MDL of 0.1 mg kg - 1 . A majority of the samples (93%) had concentrations below 10 mg kg - 1 , which indicate the presence of endogenous nitrates. The samples with concentrations above 10 mg kg - 1 were mainly processed cheese spread, which can contain additional ingredients often of plant-based origin. These ingredients are likely the cause of the elevated nitrate concentrations. The analysis of 12 additional cheese samples that are liable to the intentional addition of nitrates, 9 of which were imported, indicated that in this limited study, concentrations of nitrate in the U.S.-produced cheeses did not differ from those in imported samples.

  9. Selected cerium phase diagrams

    International Nuclear Information System (INIS)

    Gschneidner, K.A. Jr.; Verkade, M.E.

    1974-09-01

    A compilation of cerium alloy phase equilibria data based on the most reliable information available is presented. The binary systems selected are those of cerium with each of the following twenty nine elements which might be commonly found in steels: Al, Sb, As, Bi, Ca, C, Cr, Co, Nb, Cu, Fe, Pb, Mg, Mn, Mo, Ni, N, O, P, Se, Si, Ag, S, Te, Sn, Ti, W, and Zn. A brief discussion, a summary of crystal lattice parameters where applicable, and a list of references is included for each element surveyed. (U.S.)

  10. Method of cerium separation from other lanthanides and yttrium

    International Nuclear Information System (INIS)

    Tran, Duc Hiep; Mostecky, J.

    1988-01-01

    Cerium is separated from a suspension produced during the aerial oxidation process. The suspension is subject to a cyclic process of two-stage fractional dissolution. Following the first dissolution, almost all cerium remains undissolved while 95% of the other lanthanides pass into the solution. The filtrate of the second stage of dissolution containing about 5% of ceriumm is returned for oxidation with the next batch of hydroxide mixed concentrate. Following oxidation, the two-stage fractional dissolution is repeated. This cycling provides quantitative cerium separation from other rare earth elements. (E.S.)

  11. Development of biological treatment of high concentration sodium nitrate waste liquid

    International Nuclear Information System (INIS)

    Ogawa, Naoki; Kuroda, Kazuhiko; Shibata, Katsushi; Kawato, Yoshimi; Meguro, Yoshihiro; Takahashi, Kuniaki

    2009-01-01

    An electrolytic reduction, chemical reduction, and biological reduction have been picked up as a method of nitrate liquid waste treatment system exhausted from the reprocessing process. As a result of comparing them, it was shown that the biological treatment was the most excellent method in safety and the economy. (author)

  12. Aluminide slurry coatings for protection of ferritic steel in molten nitrate corrosion for concentrated solar power technology

    Science.gov (United States)

    Audigié, Pauline; Bizien, Nicolas; Baráibar, Ignacio; Rodríguez, Sergio; Pastor, Ana; Hernández, Marta; Agüero, Alina

    2017-06-01

    Molten nitrates can be employed as heat storage fluids in solar concentration power plants. However molten nitrates are corrosive and if operating temperatures are raised to increase efficiencies, the corrosion rates will also increase. High temperature corrosion resistant coatings based on Al have demonstrated excellent results in other sectors such as gas turbines. Aluminide slurry coated and uncoated P92 steel specimens were exposed to the so called Solar Salt (industrial grade), a binary eutectic mixture of 60 % NaNO3 - 40 % KNO3, in air for 2000 hours at 550°C and 580°C in order to analyze their behavior as candidates to be used in future solar concentration power plants employing molten nitrates as heat transfer fluids. Coated ferritic steels constitute a lower cost technology than Ni based alloy. Two different coating morphologies resulting from two heat treatment performed at 700 and 1050°C after slurry application were tested. The coated systems exhibited excellent corrosion resistance at both temperatures, whereas uncoated P92 showed significant mass loss from the beginning of the test. The coatings showed very slow reaction with the molten Solar Salt. In contrast, uncoated P92 developed a stratified, unprotected Fe, Cr oxide with low adherence which shows oscillating Cr content as a function of coating depth. NaFeO2 was also found at the oxide surface as well as within the Fe, Cr oxide.

  13. Concentration and Transport of Nitrate by the Mat-Forming Sulfur Bacterium Thioploca Rid E-1821-2011

    DEFF Research Database (Denmark)

    FOSSING, H.; GALLARDO, VA; JØRGENSEN, BB

    1995-01-01

    MARINE species of Thioploca occur over 3,000 km along the continental shelf off Southern Peru and North and Central Chile(1-4). These filamentous bacteria live in bundles surrounded by a common sheath and form thick mats on the sea floor under the oxygen-minimum zone in the upwelling region......, at between 40 and 280 m water depth. The metabolism of this marine bacterium(5,6) remained a mystery until long after its discovery(1,7). We report here that Thioploca cells are able to concentrate nitrate to up to 500 mM in a liquid vacuole that occupies >80% of the cell volume. Gliding filaments transport...... this nitrate 5-10 cm down into the sediment and reduce it, with concomitant oxidation of hydrogen sulphide, thereby coupling the nitrogen and sulphur cycles in the sediment....

  14. Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce canopy

    Directory of Open Access Journals (Sweden)

    V. Wolff

    2010-05-01

    Full Text Available Total ammonium (tot-NH4+ and total nitrate (tot-NO3 provide chemically conservative quantities in the measurement of surface exchange of reactive nitrogen compounds ammonia (NH3, particulate ammonium (NH4+, nitric acid (HNO3, and particulate nitrate (NO3, using the aerodynamic gradient method. Total fluxes were derived from concentration differences of total ammonium (NH3 and NH4+ and total nitrate (HNO3 and NO3 measured at two levels. Gaseous species and related particulate compounds were measured selectively, simultaneously and continuously above a spruce forest canopy in south-eastern Germany in summer 2007. Measurements were performed using a wet-chemical two-point gradient instrument, the GRAEGOR. Median concentrations of NH3, HNO3, NH4+, and NO3 were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total ammonium and total nitrate fluxes showed large variations depending on meteorological conditions, with concentrations close to zero under humid and cool conditions and higher concentrations under dry conditions. Mean fluxes of total ammonium and total nitrate in September 2007 were directed towards the forest canopy and were −65.77 ng m−2 s−1 and −41.02 ng m−2 s−1 (in terms of nitrogen, respectively. Their deposition was controlled by aerodynamic resistances only, with very little influence of surface resistances. Including measurements of wet deposition and findings of former studies on occult deposition (fog water interception at the study site, the total N deposition in September 2007 was estimated to 5.86 kg ha−1.

  15. Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions

    OpenAIRE

    Mehdi, Hasan; Bodor, Andrea; Lantos, Diana; Horváth, István T; De Vos, Dirk; Binnemans, Koen

    2007-01-01

    Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Ca...

  16. Solvent extraction of cerium (III) with high molecular weight amines

    International Nuclear Information System (INIS)

    Chatterjee, A.; Basu, S.

    1992-01-01

    The use of high molecular weight amines in the extraction of cerium (III) as EDTA complex from neutral aqueous medium is reported. The extraction condition was optimised from the study of effects of several variables like concentration of amine and EDTA pH nature of diluents etc. The method has been applied for the determination of cerium in few mineral samples. (author). 7 refs., 5 tabs

  17. Fundamental aspects of regenerative cerium oxide nanoparticles and their applications in nanobiotechnology

    Science.gov (United States)

    Patil, Swanand D.

    Cerium oxide has been used extensively for various applications over the past two decades. The use of cerium oxide nanoparticles is beneficial in present applications and can open avenues for future applications. The present study utilizes the microemulsion technique to synthesize uniformly distributed cerium oxide nanoparticles. The same technique was also used to synthesize cerium oxide nanoparticles doped with trivalent elements (La and Nd). The fundamental study of cerium oxide nanoparticles identified variations in properties as a function of particle size and also due to doping with trivalent elements (La and Nd). It was found that the lattice parameter of cerium oxide nanoparticles increases with decrease in particle size. Also Raman allowed mode shift to lower energies and the peak at 464 cm-1 becomes broader and asymmetric. The size dependent changes in cerium oxide were correlated to increase in oxygen vacancy concentration in the cerium oxide lattice. The doping of cerium oxide nanoparticles with trivalent elements introduces more oxygen vacancies and expands the cerium oxide lattice further (in addition to the lattice expansion due to the size effect). The lattice expansion is greater for La-doped cerium oxide nanoparticles compared to Nd-doping due to the larger ionic radius of La compared to Nd, the lattice expansion is directly proportional to the dopant concentration. The synthesized cerium oxide nanoparticles were used to develop an electrochemical biosensor of hydrogen peroxide (H2O2). The sensor was useful to detect H2O2 concentrations as low as 1muM in water. Also the preliminary testing of the sensor on tomato stem and leaf extracts indicated that the sensor can be used in practical applications such as plant physiological studies etc. The nanomolar concentrations of cerium oxide nanoparticles were also found to be useful in decreasing ROS (reactive oxygen species) mediated cellular damages in various in vitro cell cultures. Cerium oxide

  18. Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations

    Directory of Open Access Journals (Sweden)

    G. Prabhakar

    2017-12-01

    Full Text Available This study discusses an analysis of combined airborne and ground observations of particulate nitrate (NO3−(p concentrations made during the wintertime DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically resolved observations relevant to Air Quality study at one of the most polluted cities in the United States – Fresno, CA – in the San Joaquin Valley (SJV and focuses on developing an understanding of the various processes that impact surface nitrate concentrations during pollution events. The results provide an explicit case-study illustration of how nighttime chemistry can influence daytime surface-level NO3−(p concentrations, complementing previous studies in the SJV. The observations exemplify the critical role that nocturnal chemical production of NO3−(p aloft in the residual layer (RL can play in determining daytime surface-level NO3−(p concentrations. Further, they indicate that nocturnal production of NO3−(p in the RL, along with daytime photochemical production, can contribute substantially to the buildup and sustaining of severe pollution episodes. The exceptionally shallow nocturnal boundary layer (NBL heights characteristic of wintertime pollution events in the SJV intensify the importance of nocturnal production aloft in the residual layer to daytime surface concentrations. The observations also demonstrate that dynamics within the RL can influence the early-morning vertical distribution of NO3−(p, despite low wintertime wind speeds. This overnight reshaping of the vertical distribution above the city plays an important role in determining the net impact of nocturnal chemical production on local and regional surface-level NO3−(p concentrations. Entrainment of clean free-tropospheric (FT air into the boundary layer in the afternoon is identified as an important process that reduces surface-level NO3−(p and limits buildup during pollution episodes. The influence of dry deposition of HNO

  19. A novel modelling approach for spatial and temporal variations in nitrate concentrations in an N-impacted UK small upland river basin

    International Nuclear Information System (INIS)

    Smart, Richard P.; Cresser, Malcolm S.; Calver, Louise J.; Clark, Matthew; Chapman, Pippa J.

    2005-01-01

    Monthly data for 11 moorland streams displaying marked seasonality and spatial variation in nitrate concentrations have been used with readily available catchment characteristics to develop a method for predicting stream water nitrate concentrations throughout an upland river network in the Lake District, UK. Over a 12-month period, a simple asymmetric truncated cosine function of day number is used to describe seasonality effects on stream water nitrate concentrations. This is then adjusted to compensate for differences in seasonality effects with catchment elevation. Occurrence of greater proportions of steeper slopes (>20 deg. -40 deg. ) in individual catchments facilitated nitrate leaching, as did increased extent of occurrence of outcropping rocks. It is shown that the spatial and temporal variation in nitrate concentration through the river network studied may therefore be effectively represented by an equation which is a function of day number, % outcropping rock and % of catchment area with a >20 deg. -40 deg. slope. - A novel model of spatial and temporal variations in stream water nitrate concentration throughout an N-impacted upland catchment is described

  20. Using paired in situ high frequency nitrate measurements to better understand controls on nitrate concentrations and estimate nitrification rates in a wastewater-impacted river

    Science.gov (United States)

    Kraus, Tamara; O'Donnell, Katy; Downing, Bryan D.; Burau, Jon R.; Bergamaschi, Brian

    2017-01-01

    We used paired continuous nitrate ( ) measurements along a tidally affected river receiving wastewater discharge rich in ammonium ( ) to quantify rates of change in  concentration ( ) and estimate nitrification rates.  sensors were deployed 30 km apart in the Sacramento River, California (USA), with the upstream station located immediately above the regional wastewater treatment plant (WWTP). We used a travel time model to track water transit between the stations and estimated  every 15 min (October 2013 to September 2014). Changes in concentration were strongly related to water temperature. In the presence of wastewater, was generally positive, ranging from about 7 µM d−1 in the summer to near zero in the winter. Numerous periods when the WWTP halted discharge allowed the  to be estimated under no-effluent conditions and revealed that in the absence of effluent, net gains in  were substantially lower but still positive in the summer and negative (net sink) in the winter. Nitrification rates of effluent-derived NH4 ( ) were estimated from the difference between  measured in the presence versus absence of effluent and ranged from 1.5 to 3.4 µM d−1, which is within literature values but tenfold greater than recently reported for this region.  was generally lower in winter (∼2 µM d−1) than summer (∼3 µM d−1). This in situ, high frequency approach provides advantages over traditional discrete sampling, incubation, and tracer methods and allows measurements to be made over broad areas for extended periods of time. Incorporating this approach into environmental monitoring programs can facilitate our ability to protect and manage aquatic systems.

  1. The Transboundary Aquifer Management Challenge: Linking Landscape Patterns and Groundwater Nitrate Concentrations in the Abbotsford-Sumas Aquifer, USA/Canada

    Science.gov (United States)

    Gallagher, T.; Gergel, S. E.

    2015-12-01

    Changes in land use and landscape pattern can have an array of impacts on aquatic systems, including impacts which span international waters and borders. Globally, agricultural land use patterns and practices are among the factors responsible for elevated nitrate concentrations in groundwater aquifers. Coordination of landscape monitoring across trans-boundary aquifers is needed to monitor and address contamination issues as landscape patterns can vary widely among different political jurisdictions. Landscape indicators, which quantify the amount and arrangement of land cover (such as proportion and abundance of land cover types), are one such way to improve our understanding of cross-border aquatic system interactions. In Western North America, the Abbotsford-Sumas Aquifer (ASA) spans the US-Canada border and provides drinking water for over 100,000 people. Intensive agriculture combined with high precipitation and well-drained soils make this aquifer susceptible to nitrate leaching. To understand how landscape patterns influence nitrate concentrations, we ask: Which landscape indicators correlate most strongly with elevated nitrate concentrations? A seamless cross-border land cover mosaic was created by harmonizing a variety of US and Canadian geodata. Auxiliary high spatial resolution imagery (e.g., 5m RapidEye and historical Google Earth) were used to quantify fine-scale landscape features (such as number of farm field renovations) with suspected mechanistic links to nitrate sources. We examined groundwater nitrate concentrations in shallow wells (screens Environment Canada. Surrounding each well, terrestrial zones of influence (aligned with the directional flow of groundwater) were delineated within which landscape patterns were characterized. Multiple regression was used to compare the strength of relationships between land use practices and nitrate concentrations. Preliminary results show strong positive correlations between area of raspberry renovations and

  2. Preparation and characterization of gelatin/cerium(Ⅲ) film

    Institute of Scientific and Technical Information of China (English)

    黄崇军; 黄雅钦; 田娜; 童元建; 殷瑞贤

    2010-01-01

    A novel gelatin film with antibacterial activity was prepared by electrostatic crosslinking using cerium (Ⅲ) nitrate hexahydrate as the crosslinking agent. The structure and properties of the films were investigated by Fourier transform infrared spectra, tensile tests, thermogravimetric analysis, static drop contact angle and disc diffusion method. The results showed that cross-linking could not only improve the thermal and mechanical properties and lower the hydrophilic property of the films, but also make...

  3. A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II).

    Science.gov (United States)

    Rao, G G; Rao, P K

    1967-01-01

    Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.

  4. Geographic variation in the relationships of temperature, salinity or sigma sub t versus plant nutrient concentrations in the world ocean. [silicic acid, nitrate, and phosphate concentration

    Science.gov (United States)

    Kamykowski, D.; Zentara, S. J.

    1985-01-01

    A NODC data set representing all regions of the world ocean was analyzed for temperature and sigma-t relationships with nitrate, phosphate or silicic acid. Six cubic regressions were for each ten degree square of latitude and longitude containing adequate data. World maps display the locations that allow the prediction of plant nutrient concentrations from temperature or sigma-t. Geographic coverage improves along the sequence: nitrate, phosphate, and silicic acid and is better for sigma-t than for temperature. Contour maps of the approximate temperature of sigma-t at which these nitrients are no longer measurable in a parcel of water are generated, based on a percentile analysis of the temperature or sigma-t at which less than a selected amount of plant nutrient occurs. Results are stored on magnetic tape in tabular form. The global potential to predict plant nutrient concentrations from remotely sensed temperature of sigma-t and to emphasize the latitudinally and longitudinally changing phytoplankton growth environment in present and past oceans is demonstrated.

  5. Effect of polyvinylpyrrolidone on cerium oxide nanoparticle characteristics prepared by a facile heat treatment technique

    Directory of Open Access Journals (Sweden)

    Anwar Ali Baqer

    Full Text Available An aqueous medium composed of polyvinylpyrrolidone (PVP and cerium nitrates at calcination temperature was utilised in the production of cerium oxide (CeO2 semiconductor nanoparticles. A variety of analytical approaches was utilized to examine the structural, morphological and optical characteristics of the resulting nanoparticles. Differential thermal (DTA and thermogravimetric (TGA analyses, indicated that the best calcination temperatures for achieving CeO2 nanoparticle production were more than 485 °C. The results from Fourier-transform infrared (FTIR verified the formation of a crystalline structure after calcination procedures were performed to remove residual organic compounds. Additionally, results from X-ray diffraction (XRD analysis confirmed the cubic fluorite structure of the CeO2 produced. Samples were also analysed by energy dispersive spectroscopy (EDXA which indicated the existence of O and Ce in the samples. Field emission scanning electron microscopy (FESEM was used in the characterisation of nanoparticle morphological features. Transmission electron microscopy (TEM was employed to estimate typical nanoparticle and distribution within sample. This analysis indicated that mean particle sizes were inversely correlated with PVP concentration, with nanoparticle sizes ranging between 12 ± 7 nm at 0.03 g/mL PVP and 6 ± 2 nm at 0.05 g/mL PVP. These results corroborated those obtained by XRD analysis. A UV–vis spectrophotometer was utilised in the demonstration of optical properties and to examine the band gap energy of samples. The potential UV-shielding properties of the nanoparticles were demonstrated by the observed blue shift of the estimated optical energy band, i.e. from 3.35 to 3.43 eV, whilst PL spectra results indicated that decreasing particle size was associated with diminishing photoluminescence intensity. Keywords: Cerium oxide nanoparticles, Heat treatment technique, Structural properties, Optical

  6. The effect of concentration and exposure time on 15N uptake and incorporation from urea and ammonium nitrate by spring barley in the initial growth period

    International Nuclear Information System (INIS)

    Matula, J.; Knop, K.

    1978-01-01

    The uptake and incorporation of 15 N from urea and ammonium nitrate by spring barley were studied in aquaculture at three nitrogen concentrations in complex nutrient solutions (28, 140 and 700 mg N per 1 litre) and for three lengths of exposure to 15 N-labelled nutrient solutions. The 'Diamant' variety plants were precultivated up to the stage of the 3rd to 4th leaf in a complex nutrient solution, and five days prior to exposure to 15 N-labelled solutions the plants were cultivated in a nutrient solution without nitrogen. At a concentration of 28 mg N per litre the course of urea absorption was similar to the absorption of ammonium nitrate, but at a lower level. The results suggest that urea uptake is basically controlled by the metabolic requirement, particularly at lower concentrations. Only at the highest concentrations of nitrogen in the nutrient solutions did the 15 N of urea and ammonium nitrate penetrate into the roots, passive uptake being preferred. The uptake of urea is controlled by the metabolic requirement but its availability for barley metabolism is lower. Ammonium nitrate NO 3 - was taken up at a lower rate than NH 4 + from the same compound. Nitrate nitrogen was transported relatively more intensively to the above-ground parts of barley. The increasing concentration of nitrogen and exposure to nutrient solutions induced a rise in the proportion of ethanol-soluble forms of nitrogen, particularly in the roots. (author)

  7. In what root-zone N concentration does nitrate start to leach significantly? A reasonable answer from modeling Mediterranean field data and closed root-zone experiments

    Science.gov (United States)

    Kurtzman, D.; Kanner, B.; Levy, Y.; Shapira, R. H.; Bar-Tal, A.

    2017-12-01

    Closed-root-zone experiments (e.g. pots, lyzimeters) reveal in many cases a mineral-nitrogen (N) concentration from which the root-N-uptake efficiency reduces significantly and nitrate leaching below the root-zone increases dramatically. A les-direct way to reveal this threshold concentration in agricultural fields is to calibrate N-transport models of the unsaturated zone to nitrate data of the deep samples (under the root-zone) by fitting the threshold concentration of the nitrate-uptake function. Independent research efforts of these two types in light soils where nitrate problems in underlying aquifers are common reviled: 1) that the threshold exists for most crops (filed, vegetables and orchards); 2) nice agreement on the threshold value between the two very different research methodologies; and 3) the threshold lies within 20-50 mg-N/L. Focusing on being below the threshold is a relatively simple aim in the way to maintain intensive agriculture with limited effects on the nitrate concentration in the underlying water resource. Our experience show that in some crops this threshold coincides with the end-of-rise of the N-yield curve (e.g. corn); in this case, it is relatively easy to convince farmers to fertilize below threshold. In other crops, although significant N is lost to leaching the crop can still use higher N concentration to increase yield (e.g. potato).

  8. Experimental additions of aluminum sulfate and ammonium nitrate to in situ mesocosms to reduce cyanobacterial biovolume and microcystin concentration

    Science.gov (United States)

    Harris, Ted D.; Wilhelm, Frank M.; Graham, Jennifer L.; Loftin, Keith A.

    2014-01-01

    Recent studies suggest that nitrogen additions to increase the total nitrogen:total phosphorus (TN:TP) ratio may reduce cyanobacterial biovolume and microcystin concentration in reservoirs. In systems where TP is >100 μg/L, however, nitrogen additions to increase the TN:TP ratio could cause ammonia, nitrate, or nitrite toxicity to terrestrial and aquatic organisms. Reducing phosphorus via aluminum sulfate (alum) may be needed prior to nitrogen additions aimed at increasing the TN:TP ratio. We experimentally tested this sequential management approach in large in situ mesocosms (70.7 m3) to examine effects on cyanobacteria and microcystin concentration. Because alum removes nutrients and most seston from the water column, alum treatment reduced both TN and TP, leaving post-treatment TN:TP ratios similar to pre-treatment ratios. Cyanobacterial biovolume was reduced after alum addition, but the percent composition (i.e., relative) cyanobacterial abundance remained unchanged. A single ammonium nitrate (nitrogen) addition increased the TN:TP ratio 7-fold. After the TN:TP ratio was >50 (by weight), cyanobacterial biovolume and abundance were reduced, and chrysophyte and cryptophyte biovolume and abundance increased compared to the alum treatment. Microcystin was not detectable until the TN:TP ratio was <50. Although both treatments reduced cyanobacteria, only the nitrogen treatment seemed to stimulate energy flow from primary producers to zooplankton, which suggests that combining alum and nitrogen treatments may be a viable in-lake management strategy to reduce cyanobacteria and possibly microcystin concentrations in high-phosphorus systems. Additional studies are needed to define best management practices before combined alum and nitrogen additions are implemented as a reservoir management strategy.

  9. Synthesis of cerium oxide (CeO{sub 2}) nanoparticles using simple CO-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Farahmandjou, M.; Zarinkamar, M.; Firoozabadi, T. P., E-mail: farahamndjou@iauvaramin.ac.ir [Islamis Azad University, Varamin-Phisva Branch, Department of Physics, Varamin (Iran, Islamic Republic of)

    2016-11-01

    Synthesis of cerium oxide (CeO{sub 2}) nanoparticles was studied by new and simple co-precipitation method. The cerium oxide nanoparticles were synthesized using cerium nitrate and potassium carbonate precursors. Their physicochemical properties were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (Sem), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (Ftir) and UV-Vis spectrophotometer. XRD pattern showed the cubic structure of the cerium oxide nanoparticles. The average particle size of CeO{sub 2} was around 20 nm as estimated by XRD technique and direct HRTEM observations. The surface morphological studies from Sem and Tem depicted spherical particles with formation of clusters. The sharp peaks in Ftir spectrum determined the existence of CeO{sub 2} stretching mode and the absorbance peak of UV-Vis spectrum showed the bandgap energy of 3.26 eV. (Author)

  10. Optical properties of cerium oxide (CeO2) nanoparticles synthesized by hydroxide mediated method

    Science.gov (United States)

    Ali, Mawlood Maajal; Mahdi, Hadeel Salih; Parveen, Azra; Azam, Ameer

    2018-05-01

    The nanoparticles of cerium oxide have been successfully synthesized by hydroxide mediated method, using cerium nitrate and sodium hydroxide as precursors. The microstructural properties were analyzed by X-ray diffraction technique (XRD). The X-ray diffraction results show that the cerium oxide nanoparticles were in cubic structure. The optical absorption spectra of cerium oxide were recorded by UV-VIS spectrophotometer in the range of 320 to 600 nm and photoluminescence spectra in the range of 400-540 nm and have been presented. The energy band gap was determined by Tauc relationship. The crystallite size was determined from Debye-Scherer equation and came out to be 6.4 nm.

  11. Changes in stream nitrate concentrations due to land management practices, ecological succession, and climate: Developing a system approach to integrated catchment response

    Science.gov (United States)

    F. Worrall; Wayne T. Swank; T. P. Burt

    2003-01-01

    This study uses time series analysis to examine long-term stream water nitrate concentration records from a pair of forested catchments at the Coweeta Hydrologic Laboratory, North Carolina, USA. Monthly average concentrations were available from 1970 through 1997 for two forested catchments, one of which was clear-felled in 1977 and the other maintained as a control....

  12. Practical use of the fertigation control based on cumulative solar radiation to decrease the nitrate concentration in spinach [Spinacia oleracea] grown in the greenhouse

    International Nuclear Information System (INIS)

    Shinohara, Y.; Tsukagoshi, S.; Hayashi, N.; Maruo, T.; Hohjo, M.

    2007-01-01

    Spinach plants (Spinacia oleracea L.) were grown in a greenhouse using fertigation based on cumulative solar radiation, and effects on plant growth, nitrate concentration in the leaves, and nitrate utilization/application ratio were studied. The relation of water and NO3-N absorption to cumulative solar radiation was initially determined in hydroponically grown spinach, then the stepwise fertigation program was set to 1.0, 1.2 and 1.4 times the standard quantity. With 1.2 fertigation treatment, plant growth and leaf color did not differ from those of plants cultivated by conventional soil culture. Total nitrate supplied to the soil under fertigation treatment were about half of that at soil culture. The nitrate utilization/application ratio was increased from 44% in soil culture to 82% under fertigation treatment. The nitrate concentration in spinach leaves under fertigation treatments tended to be lower compared to those under soil culture. In addition, the production of spinach with lower nitrate and without effects on growth seemed to be feasible by the withdrawal of NO3-N in the drip solution for several days before harvest

  13. Reflectance degradation of a secondary concentrator by nitrate salt vapor deposition in an open volumetric receiver configuration

    Science.gov (United States)

    Lahlou, Radia; Armstrong, Peter R.; Calvet, Nicolas; Shamim, Tariq

    2017-06-01

    Nitrate salt vapor deposition on the reflecting surface of a secondary concentrator placed on top of an open molten salt tank at 500 °C is investigated using a lab-scale setup over an 8h-exposure cycle. Deposition, consisting of mostly spherical particles, is characterized in terms of chemical composition using energy dispersive X-ray spectroscopy. The corresponding specular reflectance degradation both temporary (before washing off the salt deposits) and permanent (residual reflectance loss after cleaning), is measured at different incidence angles and at reference points located at different heights. Reflectance drop due to salt deposits is compared to the one resulting from dust deposition. Long-term reflectance degradation by means of corrosion needs to be further studied through suitable accelerated aging tests.

  14. Long term dynamics of nitrate concentrations and leaching losses in tile drainage water from cultivated clayey till at field scale

    DEFF Research Database (Denmark)

    Ernstsen, Vibeke; Olsen, Preben; Rosenbom, Annette Elisabeth

    2014-01-01

    of application). Furthermore, the standard climatic conditions (e.g. temperature, precipitation) as well as soil moisture and temperature to a depth of approx. 2 meter were measured. Concentrations of nitrate in the drainage and groundwater, recharge of water through the drainage system as well as depth......Since 1985, several political agreements have been adopted to protect the aquatic environment and nature in Denmark. The farmers have repeatedly been ordered to reduce the consumption of nitrogen in their agricultural production. The reductions have been imposed nation-wide regardless of e.......g. climate, soil type and local hydraulic conditions. By the end of 2013, the Danish Commission of Nature and Agriculture issued a report which recommend that for the future protection of surface nitrogen regulations should be locally adapted, and if possible, at the level of field scale. This kind...

  15. Preparation of cerium oxide for lens polishing powder

    International Nuclear Information System (INIS)

    Injarean, Uthaiwan; Rodthongkom, Chouvana; Pichestapong, Pipat; Changkrurng, Kalaya

    2003-10-01

    Cerium is an element of rare earth group which is called lanthanide series. It is found in the ores like monazite and xenotime which are the tailings of tin mines in the south of Thailand. Cerium is used mostly as lens polishing powder besides the applications in other industries. In this study, cerium extracted from monazite ore breakdown by alkaline process was used for the preparation of lens polishing powder. Cerium hydroxide cake from the process was dissolved by hydrochloric acid and precipitated with oxalic acid. The oxalate precipitate then was calcined to oxide powder and its particle size was measured. Precipitation conditions being studied are concentration of feed cerium chloride solution, concentration of oxalic acid used for the precipitation, concentration of sulfuric acid used as precipitation control reagent and the precipitation temperature. It was found that the appropriate precipitation conditions yielded the fine oxide powder with particle size about 12μm. The oxide powder can be ground to the size of 1-3 μm which is suitable for making lens polishing powder

  16. Relationships between stream nitrate concentration and spatially distributed snowmelt in high-elevation catchments of the western U.S.

    Science.gov (United States)

    Perrot, Danielle; Molotch, Noah P.; Williams, Mark W.; Jepsen, Steven M.; Sickman, James O.

    2014-11-01

    This study compares stream nitrate (NO3-) concentrations to spatially distributed snowmelt in two alpine catchments, the Green Lakes Valley, Colorado (GLV4) and Tokopah Basin, California (TOK). A snow water equivalent reconstruction model and Landsat 5 and 7 snow cover data were used to estimate daily snowmelt at 30 m spatial resolution in order to derive indices of new snowmelt areas (NSAs). Estimates of NSA were then used to explain the NO3- flushing behavior for each basin over a 12 year period (1996-2007). To identify the optimal method for defining NSAs and elucidate mechanisms underlying catchment NO3- flushing, we conducted a series of regression analyses using multiple thresholds of snowmelt based on temporal and volumetric metrics. NSA indices defined by volume of snowmelt (e.g., snowmelt ≤ 30 cm) rather than snowmelt duration (e.g., snowmelt ≤ 9 days) were the best predictors of stream NO3- concentrations. The NSA indices were better correlated with stream NO3- concentration in TOK (average R2= 0.68) versus GLV4 (average R2= 0.44). Positive relationships between NSA and stream NO3- concentration were observed in TOK with peak stream NO3- concentration occurring on the rising limb of snowmelt. Positive and negative relationships between NSA and stream NO3- concentration were found in GLV4 with peak stream NO3- concentration occurring as NSA expands. Consistent with previous works, the contrasting NO3- flushing behavior suggests that streamflow in TOK was primarily influenced by overland flow and shallow subsurface flow, whereas GLV4 appeared to be more strongly influenced by deeper subsurface flow paths.

  17. Nitrate accumulation in spinach

    NARCIS (Netherlands)

    Steingröver, Eveliene Geertruda

    1986-01-01

    Leafy vegetables, like spinach, may contain high concentrations of nitrate. In the Netherlands, about 75% of mean daily intake of nitrate orginates from the consumption of vegatables. Hazards to human health are associated with the reduction of nitrate to nitrite. Acute nitrite poisoning causes

  18. Effects of elevated CO2 concentration on growth and water usage of tomato seedlings under different ammonium/nitrate ratios

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Increasing atmospheric CO2 concentration is generally expected to enhance photosynthesis and growth of agricultural C3 vegetable crops,and therefore results in an increase in crop yield.However,little is known about the combined effect of elevated CO2 and N species on plant growth and development.Two growth-chamber experiments were conducted to determine the effects of NH4+/NO3- ratio and elevated CO2 concentration on the physiological development and water use of tomato seedlings.Tomato was grown for 45 d in containers with nutrient solutions varying in NH4+/NO3- ratios and CO2 concentrations in growth chambers.Results showed that plant height,stem thickness,total dry weight,dry weight of the leaves,stems and roots,G value (total plant dry weight/seedling days),chlorophyll content,photosynthetic rate,leaf-level and whole plant-level water use efficiency and cumulative water consumption of tomato seedlings were increased with increasing proportion of NO3- in nutrient solutions in the elevated CO2 treatment.Plant biomass,plant height,stem thickness and photosynthetic rate were 67%,22%,24% and 55% higher at elevated CO2 concentration than at ambient CO2 concentration,depending on the values of NH4+/NO3- ratio.These results indicated that elevating CO2 concentration did not mitigate the adverse effects of 100% NH4+-N (in nutrient solution) on the tomato seedlings.At both CO2 levels,NH4+/NO3- ratios of nutrient solutions strongly influenced almost every measure of plant performance,and nitrate-fed plants attained a greater biomass production,as compared to ammonium-fed plants.These phenomena seem to be related to the coordinated regulation of photosynthetic rate and cumulative water consumption of tomato seedlings.

  19. Specification and comparative calculation of enthalpies and Gibbs formation energies of anhydrous lanthanide nitrates

    International Nuclear Information System (INIS)

    Del' Pino, Kh.; Chukurov, P.M.; Drakin, S.I.

    1980-01-01

    Analyzed are the results of experimental depermination of formation enthalpies of waterless nitrates of lanthane cerium, praseodymium, neodymium and samarium. Using method of comparative calculation computed are enthalpies of formation of waterless lanthanide and yttrium nitrates. Calculated values of enthalpies and Gibbs energies of waterless lanthanide nitrate formation are tabulated

  20. Cyclic variations in nitrogen uptake rate of soybean plants: effects of external nitrate concentration

    Science.gov (United States)

    Tolley-Henry, L.; Raper, C. D. Jr; Granato, T. C.; Raper CD, J. r. (Principal Investigator)

    1988-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic cultures containing 0.5, 1.0 and 10.0 mol m-3 NO3- was measured daily during a 24-d period of vegetative development to determine if amplitude of maximum and minimum rates of net NO3- uptake are responsive to external concentrations of NO3-. Removal of NO3- from the replenished solutions during each 24-h period was determined by ion chromatography. Neither dry matter accumulation nor the periodicity of oscillations in net uptake rate was altered by the external NO3- concentrations. The maxima of the oscillations in net uptake rate, however, increased nearly 3-fold in response to external NO3- concentrations. The maxima and minima, respectively, changed from 4.0 and 0.6 mmol NO3- per gram root dry weight per day at an external solution level of 0.5 mol m-3 NO3- to 15.2 and -2.7 mmol NO3- per gram root dry weight per day at an external solution level of 10.0 mol m-3 NO3-. The negative values for minimum net uptake rate from 10.0 mol m-3 NO3- solutions show that net efflux was occurring and indicate that the magnitude of the efflux component of net uptake was responsive to external concentration of NO3-.

  1. Nitrate and Moisture Content of Broad Permafrost Landscape Features in the Barrow Peninsula: Predicting Evolving NO3 Concentrations in a Changing Arctic

    Science.gov (United States)

    Arendt, C. A.; Heikoop, J. M.; Newman, B. D.; Wales, N. A.; McCaully, R. E.; Wilson, C. J.; Wullschleger, S.

    2017-12-01

    The geochemical evolution of Arctic regions as permafrost degrades, significantly impacts nutrient availability. The release of nitrogen compounds from permafrost degradation fertilizes both microbial decomposition and plant productivity. Arctic warming promotes permafrost degradation, causing geomorphic and hydrologic transitions that have the potential to convert saturated zones to unsaturated zones and subsequently alter the nitrate production capacity of permafrost regions. Changes in Nitrate (NO3-) content associated with shifting moisture regimes are a primary factor determining Arctic fertilization and subsequent primary productivity, and have direct feedbacks to carbon cycling. We have documented a broad survey of co-located soil moisture and nitrate concentration measurements in shallow active layer regions across a variety of topographic features in the expansive continuous permafrost region encompassing the Barrow Peninsula of Alaska. Topographic features of interest are slightly higher relative to surrounding landscapes with drier soils and elevated nitrate, including the rims of low centered polygons, the centers of flat and high centered polygons, the rims of young, old and ancient drain thaw lake basins and drainage slopes that exist across the landscape. With this information, we model the nitrate inventory of the Barrow Peninsula using multiple geospatial approaches to estimate total area cover by unsaturated features of interest and further predict how various drying scenarios increase the magnitude of nitrate produced in degrading permafrost regions across the Arctic. This work is supported by the US Department of Energy Next Generation Ecosystem Experiment, NGEE-Arctic.

  2. The effect of stocking rate on soil solution nitrate concentrations beneath a free-draining dairy production system in Ireland.

    Science.gov (United States)

    McCarthy, J; Delaby, L; Hennessy, D; McCarthy, B; Ryan, W; Pierce, K M; Brennan, A; Horan, B

    2015-06-01

    Economically viable and productive farming systems are required to meet the growing worldwide need for agricultural produce while at the same time reducing environmental impact. Within grazing systems of animal production, increasing concern exists as to the effect of intensive farming on potential N losses to ground and surface waters, which demands an appraisal of N flows within complete grass-based dairy farming systems. A 3-yr (2011 to 2013) whole-farm system study was conducted on a free-draining soil type that is highly susceptible to N loss under temperate maritime conditions. Soil solution concentrations of N from 3 spring-calving, grass-based systems designed to represent 3 alternative whole-farm stocking rate (SR) treatments in a post-milk quota situation in the European Union were compared: low (2.51 cows/ha), medium (2.92 cows/ha), and high SR (3.28 cows/ha). Each SR had its own farmlet containing 18 paddocks and 23 cows. Nitrogen loss from each treatment was measured using ceramic cups installed to a depth of 1m to sample the soil water. The annual and monthly average nitrate, nitrite, ammonia, and total N concentrations in soil solution collected were analyzed for each year using a repeated measures analysis. Subsequently, and based on the biological data collated from each farm system treatment within each year, the efficiency of N use was evaluated using an N balance model. Based on similar N inputs, increasing SR resulted in increased grazing efficiency and milk production per hectare. Stocking rate had no significant effect on soil solution concentrations of nitrate, nitrite, ammonia, or total N (26.0, 0.2, 2.4, and 32.3 mg/L, respectively). An N balance model evaluation of each treatment incorporating input and output data indicated that the increased grass utilization and milk production per hectare at higher SR resulted in a reduction in N surplus and increased N use efficiency. The results highlight the possibility for the sustainable

  3. Fabrication of mesoporous cerium dioxide films by cathodic electrodeposition.

    Science.gov (United States)

    Kim, Young-Soo; Lee, Jin-Kyu; Ahn, Jae-Hoon; Park, Eun-Kyung; Kim, Gil-Pyo; Baeck, Sung-Hyeon

    2007-11-01

    Mesoporous cerium dioxide (Ceria, CeO2) thin films have been successfully electrodeposited onto ITO-coated glass substrates from an aqueous solution of cerium nitrate using CTAB (Cetyltrimethylammonium Bromide) as a templating agent. The synthesized films underwent detailed characterizations. The crystallinity of synthesized CeO2 film was confirmed by XRD analysis and HR-TEM analysis, and surface morphology was investigated by SEM analysis. The presence of mesoporosity in fabricated films was confirmed by TEM and small angle X-ray analysis. As-synthesized film was observed from XRD analysis and HR-TEM image to have well-crystallized structure of cubic phase CeO2. Transmission electron microscopy and small angle X-ray analysis revealed the presence of uniform mesoporosity with a well-ordered lamellar phase in the CeO2 films electrodeposited with CTAB templating.

  4. Tissue lead concentration during chronic exposure of Pimephales promelas (fathead minnow) to lead nitrate in aquarium water.

    Science.gov (United States)

    Spokas, Eric G; Spur, Bernd W; Smith, Holly; Kemp, Francis W; Bogden, John D

    2006-11-01

    The fathead minnow is a useful species for evaluating the toxicity of wastewater effluents. While this fish is widely used for "survival" studies of metal toxicity, little or no work has been done on the tissue distribution of metals in fathead minnows. To determine the distribution of tissue lead, aquarium studies were conducted for several weeks with fish maintained in soft synthetic freshwater. Lead- (II) nitrate was added to three aquaria attaining concentrations of 20-30 ppb (aquarium B), 100-140 ppb (aquarium C), and roughly 200 ppb (aquarium D). Results were compared to controls (aquarium A). During the initial week, the majority of aquarium D fish died, whereas few deaths occurred in the other groups. Lead accumulation was dose- and tissue-dependent, with highest uptake by the gills. Gill concentrations of aquarium D fish averaged about 4-fold higherthan in skeleton or skin and muscle. In vitro, lead (2.5-25 ppm) caused dose-dependent reductions in the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) in gills incubated in physiological buffer. These findings demonstrate that fathead minnow gills bind and accumulate waterborne lead rapidly and preferentially and raise the possibility that gill lipid peroxidation contributes to lead toxicity at low water hardness.

  5. Calibration of cellulose nitrate film for measurement of time-integrated concentration of radon-222 in air

    International Nuclear Information System (INIS)

    Jha, G.; Raghavayya, M.

    1986-01-01

    Measurement of time-integrated concentration of 222 Rn in air by using solid-state nuclear track detectors (SSNTD) is finding increasing application in such diverse fields as radiation protection, exploration of radioactive minerals, prediction of earthquakes etc. While there are several types of SSNTDs sensitive to specific types of particulate radiation, films made from cellulose nitrate (CN) are found to be the best suited for quick and quantitative measurement of alpha radiation. This is because CN films are available in small thicknesses, of the order of 10-12 μm, which can be suitably evaluated by spark counting technique. This report describes the use of a sensitive thin film of CN (Kodak LR 115, Type II) for quantitative estimation of 222 Rn. The film (along with the base is exposed in a cylindrical plastic cup closed at one end with a special rubber membrane which permits discrimination of 222 Rn against 220 Rn, which is also present in air to varying extents. The calibration procedure, including etching and evaluation of track registration efficiency, are described in detail. The mean track registration efficiency works out to 41.9 per cent and the sensitivity of the system is found to be 58.92 tracks cm -2 per (Bq.litre -1 ) day. The report lists the advantages and limitations of the system for measurement of time-integrated concentration of 222 Rn in air. (author)

  6. On-line estimator/detector design for a plutonium nitrate concentrator unit

    International Nuclear Information System (INIS)

    Candy, J.V.; Rozsa, R.B.

    1979-04-01

    In this report we consider the design of a nonlinear estimator to be used in conjunction with on-line detectors for a plutonium/concentrator. Using a complex state-of-the-art process model to simulate realistic data, we show that the estimator performance using a simplified process model is adequate over a wide range of operation. The estimator is used to simulate and characterize some on-line diversion detectors, i.e., detectors designed to indicate if some of the critical special nuclear material in process is stolen or diverted from the unit. Several different diversion scenarios are presented. Simulation results indicate that the estimators and detectors yielded reasonable performance for the scenarios investigated

  7. Tyrosine nitration in blood vessels occurs with increasing nitric oxide concentration

    OpenAIRE

    Amirmansour, Charles; Vallance, Patrick; Bogle, Richard G

    1999-01-01

    Experiments were designed to explore the effects of nitric oxide (NO) donors on generation of superoxide (O2.−) and peroxynitrite (ONOO−) in rabbit aortic rings.Following inhibition of endogenous superoxide dismutase (SOD), significant basal release of O2.− was revealed (0.9±0.01×10−12 mol min−1 mg−1 tissue). Generation of O2.− increased in a concentration-dependent manner in response to NADH or NADPH (EC50=2.34±1.18×10−4 and 6.21±1.79×10−3 M respectively, n=4). NADH-stimulated O2.− chemilumi...

  8. Evaluation of hydrologic conditions and nitrate concentrations in the Rio Nigua de Salinas alluvial fan aquifer, Salinas, Puerto Rico, 2002-03

    Science.gov (United States)

    Rodriguez, Jose M.

    2006-01-01

    A ground-water quality study to define the potential sources and concentration of nitrate in the Rio Nigua de Salinas alluvial fan aquifer was conducted between January 2002 and March 2003. The study area covers about 3,600 hectares of the coastal plain within the municipality of Salinas in southern Puerto Rico, extending from the foothills to the Caribbean Sea. Agriculture is the principal land use and includes cultivation of diverse crops, turf grass, bioengineered crops for seed production, and commercial poultry farms. Ground-water withdrawal in the alluvial fan was estimated to be about 43,500 cubic meters per day, of which 49 percent was withdrawn for agriculture, 42 percent for public supply, and 9 percent for industrial use. Ground-water flow in the study area was primarily to the south and toward a cone of depression within the south-central part of the alluvial fan. The presence of that cone of depression and a smaller one located in the northeastern quadrant of the study area may contribute to the increase in nitrate concentration within a total area of about 545 hectares by 'recycling' ground water used for irrigation of cultivated lands. In an area that covers about 405 hectares near the center of the Salinas alluvial fan, nitrate concentrations increased from 0.9 to 6.7 milligrams per liter as nitrogen in 1986 to 8 to 12 milligrams per liter as nitrogen in 2002. Principal sources of nitrate in the study area are fertilizers (used in the cultivated farmlands) and poultry farm wastes. The highest nitrogen concentrations were found at poultry farms in the foothills area. In the area of disposed poultry farm wastes, nitrate concentrations in ground water ranged from 25 to 77 milligrams per liter as nitrogen. Analyses for the stable isotope ratios of nitrogen-15/nitrogen-14 in nitrate were used to distinguish the source of nitrate in the coastal plain alluvial fan aquifer. Potential nitrate loads from areas under cultivation were estimated for the

  9. An investigation to compare the performance of methods for the determination of free acid in highly concentrated solutions of plutonium and uranium nitrate

    International Nuclear Information System (INIS)

    Crossley, D.

    1980-08-01

    An investigation has been carried out to compare the performance of the direct titration method and the indirect mass balance method, for the determination of free acid in highly concentrated solutions of uranium nitrate and plutonium nitrate. The direct titration of free acid with alkali is carried out in a fluoride medium to avoid interference from the hydrolysis of uranium or plutonium, while free acid concentration by the mass balance method is obtained by calculation from the metal concentration, metal valency state, and total nitrate concentration in a sample. The Gran plot end-point prediction technique has been used extensively in the investigation to gain information concerning the hydrolysis of uranium and plutonium in fluoride media and in other complexing media. The use of the Gran plot technique has improved the detection of the end-point of the free acid titration which gives an improvement in the precision of the determination. The experimental results obtained show that there is good agreement between the two methods for the determination of free acidity, and that the precision of the direct titration method in a fluoride medium using the Gran plot technique to detect the end-point is 0.75% (coefficient of variation), for a typical separation plant plutonium nitrate solution. The performance of alternative complexing agents in the direct titration method has been studied and is discussed. (author)

  10. PERSONAL, INDOOR, AND OUTDOOR CONCENTRATIONS OF PM2.5, PARTICULATE NITRATE, AND ELEMENTAL CARBON FOR INDIVIDUALS WITH COPD IN LOS ANGELES, CA

    Science.gov (United States)

    This study characterizes the personal, indoor, and outdoor concentrations of PM2.5 and the major components of PM2.5, including nitrate (NO3-), elemental carbon (EC), and the elements for individuals with chronic obstructive pulmonary disease (COPD) living in Los Angeles, CA. ...

  11. Effect of Nitrogen Form and pH of Nutrient Solution on the Shoot Concentration of Phosphorus, Nitrate, and Nitrogen of Spinach in Hydroponic Culture

    OpenAIRE

    N. Najafi; M. Parsazadeh

    2010-01-01

    In order to study the effect of nitrogen form and pH of nutrient solution on the shoot concentration of P, nitrate, organic N + inorganic ammonium, and total N of spinach, a factorial experiment was conducted with two factors including pH of nutrient solution in three levels (4.5, 6.5 and 8.0) and nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75 and 0:100). This factorial experiment was carried out in a completely randomized design with four replicatio...

  12. Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water.

    Science.gov (United States)

    Pham, Thanh Binh; Bui, Huy; Le, Huu Thang; Pham, Van Hoi

    2016-12-22

    The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG) sensing probe-which integrated in fiber laser structure-are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0-80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10 -3 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB), narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.

  13. Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water

    Directory of Open Access Journals (Sweden)

    Thanh Binh Pham

    2016-12-01

    Full Text Available The necessity of environmental protection has stimulated the development of many kinds of methods allowing the determination of different pollutants in the natural environment, including methods for determining nitrate in source water. In this paper, the characteristics of an etched fiber Bragg grating (e-FBG sensing probe—which integrated in fiber laser structure—are studied by numerical simulation and experiment. The proposed sensor is demonstrated for determination of the low nitrate concentration in a water environment. Experimental results show that this sensor could determine nitrate in water samples at a low concentration range of 0–80 ppm with good repeatability, rapid response, and average sensitivity of 3.5 × 10−3 nm/ppm with the detection limit of 3 ppm. The e-FBG sensing probe integrated in fiber laser demonstrates many advantages, such as a high resolution for wavelength shift identification, high optical signal-to-noise ratio (OSNR of 40 dB, narrow bandwidth of 0.02 nm that enhanced accuracy and precision of wavelength peak measurement, and capability for optical remote sensing. The obtained results suggested that the proposed e-FBG sensor has a large potential for the determination of low nitrate concentrations in water in outdoor field work.

  14. Nitrate pollution of groundwater

    International Nuclear Information System (INIS)

    Heaton, T.H.E.

    1986-01-01

    Concern about the possible health risks associated with the consumption of nitrate has led many countries, including South Africa, to propose that 10mg of nitrogen (as nitrate or nitrite) per liter should be the maximum allowable limit for domestic water supplies. Groundwater in certain parts of South Africa and Namibia contains nitrate in concentrations which exceed this limit. The CSIR's Natural Isotope Division has been studying the nitrogen isotope composition of the nitrate as an aid to investigation into the sources of this nitrate contamination

  15. Recent (2008-10) concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone, south-central Texas, and their potential relation to urban development in the contributing zone

    Science.gov (United States)

    Mahler, Barbara J.; Musgrove, MaryLynn; Herrington, Chris; Sample, Thomas L.

    2011-01-01

    During 2008–10, the U.S. Geological Survey, in cooperation with the City of Austin, the City of Dripping Springs, the Barton Springs/Edwards Aquifer Conservation District, the Lower Colorado River Authority, Hays County, and Travis County, collected and analyzed water samples from five streams (Barton, Williamson, Slaughter, Bear, and Onion Creeks), two groundwater wells (Marbridge well [YD–58–50–704] and Buda well [LR–58–58–403]), and the main orifice of Barton Springs in Austin, Texas, with the objective of characterizing concentrations and isotopic compositions of nitrate and concentrations of wastewater compounds in the Barton Springs zone. The Barton Springs zone is in south-central Texas, an area undergoing rapid growth in population and in land area affected by development, with associated increases in wastewater generation. Over a period of 17 months, during which the hydrologic conditions transitioned from dry to wet, samples were collected routinely from the streams, wells, and spring and, in response to storms, from the streams and spring; some or all samples were analyzed for nitrate, nitrogen and oxygen isotopes of nitrate, and waste­water compounds. The median nitrate concentrations in routine samples from all sites were higher in samples collected during the wet period than in samples collected during the dry period, with the greatest difference for stream samples (0.05 milligram per liter during the dry period to 0.96 milligram per liter for the wet period). Nitrate concentrations in recent (2008–10) samples were elevated relative to concentrations in historical (1990–2008) samples from streams and from Barton Springs under medium- and high-flow conditions. Recent nitrate concentrations were higher than historical concentrations at the Marbridge well but the reverse was true at the Buda well. The elevated concentrations likely are related to the cessation of dry conditions coupled with increased nitrogen loading in the

  16. Differential nitrate accumulation, nitrate reduction, nitrate reductase ...

    African Journals Online (AJOL)

    However, the effects of potassium nitrate were higher than sodium nitrate, which was due to the positive effects of potassium on the enzyme activity, sugars transport, water and nutrient transport, protein synthesis and carbohydrate metabolism. In conclusion, potassium nitrate has better effect on the nitrate assimilatory ...

  17. Inhibition of nitrate reduction by NaCl adsorption on a nano-zero-valent iron surface during a concentrate treatment for water reuse.

    Science.gov (United States)

    Hwang, Yuhoon; Kim, Dogun; Shin, Hang-Sik

    2015-01-01

    Nanoscale zero-valent iron (NZVI) has been considered as a possible material to treat water and wastewater. However, it is necessary to verify the effect of the matrix components in different types of target water. In this study, different effects depending on the sodium chloride (NaCl) concentration on reductions of nitrates and on the characteristics of NZVI were investigated. Although NaCl is known as a promoter of iron corrosion, a high concentration of NaCl (>3 g/L) has a significant inhibition effect on the degree of NZVI reactivity towards nitrate. The experimental results were interpreted by a Langmuir-Hinshelwood-Hougen-Watson reaction in terms of inhibition, and the decreased NZVI reactivity could be explained by the increase in the inhibition constant. As a result of a chloride concentration analysis, it was verified that 7.7-26.5% of chloride was adsorbed onto the surface of NZVI. Moreover, the change of the iron corrosion product under different NaCl concentrations was investigated by a surface analysis of spent NZVI. Magnetite was the main product, with a low NaCl concentration (0.5 g/L), whereas amorphous iron hydroxide was observed at a high concentration (12 g/L). Though the surface was changed to permeable iron hydroxide, the Fe(0) in the core was not completely oxidized. Therefore, the inhibition effect of NaCl could be explained as the competitive adsorption of chloride and nitrate.

  18. Cerium and rare earth separation process

    International Nuclear Information System (INIS)

    Martin, M.; Rollat, M.

    1986-01-01

    An aqueous solution containing cerium III and rare earths is oxidized in the anodic compartment of an electrolytic cell, cerium IV is extracted by an organic solvent, the organic phase containing Ce IV is reduced in the catodic compartment of the same electrolytic cell and cerium III is extracted in a nitric aqueous phase [fr

  19. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: influence of legacy land use.

    Science.gov (United States)

    Kent, Robert; Landon, Matthew K

    2013-05-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p<0.10) increase in nitrate and 14 wells (11%) had a significant decrease in nitrate. For TDS, 46 wells (35%) had a significant increase and 8 wells (6%) had a significant decrease. Slopes for the observed significant trends ranged from -0.44 to 0.91 mg/L/yr for nitrate (as N) and -8 to 13 mg/L/yr for TDS. Increasing nitrate trends were associated with greater well depth, higher percentage of agricultural land use, and being closer to the distal end of the flow system. Decreasing nitrate trends were associated with the occurrence of volatile organic compounds (VOCs); VOC occurrence decreases with increasing depth. The relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area. Published by Elsevier B.V.

  20. Procedure for the separation of cerium from rare earth phosphate mixtures

    International Nuclear Information System (INIS)

    Richter, H.; Grauss, H.; Schmitt, A.; Schade, H.; Lindeholz, M.; Lorenz, E.; Weickart, J.

    1986-01-01

    The invention is concerned with a procedure for the separation of cerium from rare earth concentrates originating from the partial neutralization of nitric crude phosphate decomposition solutions without preceding elimination of impurities from the raw material. The rare earth phosphates are treated with an excess of concentrated nitric acid through which the Ce 3+ , contained in the solution, is oxidized to Ce 4+ and precipitated as cerium(IV) phosphate by neutralization with alkalis

  1. HYDROGEN PRODUCTION BY THE CYANOBACTERIUM PLECTONEMA BORYANUM: EFFECTS OF INITIAL NITRATE CONCENTRATION, LIGHT INTENSITY, AND INHIBITION OF PHOTOSYSTEM II BY DCMU

    Energy Technology Data Exchange (ETDEWEB)

    Carter, B.; Huesemann, M.

    2008-01-01

    The alarming rate at which atmospheric carbon dioxide levels are increasing due to the burning of fossil fuels will have incalculable consequences if disregarded. Fuel cells, a source of energy that does not add to carbon dioxide emissions, have become an important topic of study. Although signifi cant advances have been made related to fuel cells, the problem of cheap and renewable hydrogen production still remains. The cyanobacterium Plectonema boryanum has demonstrated potential as a resolution to this problem by producing hydrogen under nitrogen defi cient growing conditions. Plectonema boryanum cultures were tested in a series of experiments to determine the effects of light intensity, initial nitrate concentration, and photosystem II inhibitor DCMU (3-(3,4- dichlorophenyl)-1,1-dimethylurea) upon hydrogen production. Cultures were grown in sterile Chu. No. 10 medium within photobioreactors constantly illuminated by halogen lights. Because the enzyme responsible for hydrogen production is sensitive to oxygen, the medium was continuously sparged with argon/CO2 (99.7%/0.3% vol/vol) by gas dispersion tubes immersed in the culture. Hydrogen production was monitored by using a gas chromatograph equipped with a thermal conductivity detector. In the initial experiment, the effects of initial nitrate concentration were tested and results revealed cumulative hydrogen production was maximum at an initial nitrate concentration of 1 mM. A second experiment was then conducted at an initial nitrate concentration of 1 mM to determine the effects of light intensity at 50, 100, and 200 μmole m-2 s-1. Cumulative hydrogen production increased with increasing light intensity. A fi nal experiment, conducted at an initial nitrate concentration of 2 mM, tested the effects of high light intensity at 200 and 400 μmole m-2 s-1. Excessive light at 400 μmole m-2 s-1 decreased cumulative hydrogen production. Based upon all experiments, cumulative hydrogen production rates were optimal

  2. Simultaneous effect of nitrate (NO3- concentration, carbon dioxide (CO2 supply and nitrogen limitation on biomass, lipids, carbohydrates and proteins accumulation in Nannochloropsis oculata

    Directory of Open Access Journals (Sweden)

    Aarón Millán-Oropeza

    2015-03-01

    Full Text Available Biodiesel from microalgae is a promising technology. Nutrient limitation and the addition of CO2 are two strategies to increase lipid content in microalgae. There are two different types of nitrogen limitation, progressive and abrupt limitation. In this work, the simultaneous effect of initial nitrate concentration, addition of CO2, and nitrogen limitation on biomass, lipid, protein and carbohydrates accumulation were analyzed. An experimental design was established in which initial nitrogen concentration, culture time and CO2 aeration as independent numerical variables with three levels were considered. Nitrogen limitation was taken into account as a categorical independent variable. For the experimental design, all the experiments were performed with progressive nitrogen limitation. The dependent response variables were biomass, lipid production, carbohydrates and proteins. Subsequently, comparison of both types of limitation i.e. progressive and abrupt limitation, was performed. Nitrogen limitation in a progressive mode exerted a greater effect on lipid accumulation. Culture time, nitrogen limitation and the interaction of initial nitrate concentration with nitrogen limitation had higher influences on lipids and biomass production. The highest lipid production and productivity were at 582 mgL-1 (49.7 % lipid, dry weight basis and 41.5 mgL-1d-1, respectively; under the following conditions: 250 mgL-1 of initial nitrate concentration, CO2 supply of 4% (v/v, 12 d of culturing and 2 d in state of nitrogen starvation induced by progressive limitation. This work presents a novel way to perform simultaneous analysis of the effect of the initial concentration of nitrate, nitrogen limitation, and CO2 supply on growth and lipid production of Nannochloropsis oculata, with the aim to produce potential biofuels feedstock.

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

    International Nuclear Information System (INIS)

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

    1993-04-01

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

  4. Valence instabilities in cerium intermetallics

    International Nuclear Information System (INIS)

    Dijkman, W.H.

    1982-01-01

    The primary purpose of this investigation was to study the magnetic behaviour of cerium in intermetallic compounds, that show an IV behaviour, e.g. CeSn 3 . In the progress of the investigations, it became of interest to study the effect of changes in the lattice of the IV compound by substituting La or Y for Ce, thus constituting the Cesub(1-x)Lasub(x)Sn 3 and Cesub(1-x)Ysub(x)Sn 3 quasibinary systems. A second purpose was to examine the possibility of introducing instabilities in the valency of a trivalent intermetallic cerium compound: CeIn 3 , also by La and Y-substitutions in the lattice. Measurements on the resulting Cesub(1-x)Lasub(x)In 3 and Cesub(1-x)Ysub(x)In 3 quasibinaries are described. A third purpose was to study the (gradual) transition from a trivalent cerium compound into an IV cerium compound. This was done by examining the magnetic properties of the CeInsub(x)Snsub(3-x) and CePbsub(x)Snsub(3-x) systems. Finally a new possibility was investigated: that of the occurrence of IV behaviour in CeSi 2 , CeSi, and in CeGa 2 . (Auth.)

  5. Phase extraction equilibria in systems rare earth (3) nitrates-ammonium nitrate-water-trialkylmethylammonium nitrate

    International Nuclear Information System (INIS)

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

    1995-01-01

    The distribution of rare earth metals (3) between aqueous and organic phases in the systems rare earth metal (3) (praseodymium-lutetium (3), yttrium (3)) nitrate-ammonium nitrate-water-trialkylmethylammonium (kerosene diluent nitrate has been studied. It is shown that in organic phase di- and trisolvates of metals (3) with tralkylmethylammonium nitrate are formed. The influence of concentration of rare earth metal (3) nitrate and ammonium nitrate on the values of extraction concentrational constants has been ascertained: they decrease with increase in the ordinal number of lanthanide (3). 11 refs., 4 figs. 1 tab

  6. Evidence for large average concentrations of the nitrate radical (NO3) in Western Europe from the HANSA hydrocarbon database

    NARCIS (Netherlands)

    Penkett, S.A.; Burgess, R.A.; Coe, H.; Coll, I.; Hov, O.; Lindskog, A.; Schmidbauer, N.; Solberg, S.; Roemer, M.; Thijsse, T.; Beck, J.; Reeves, C.E.

    2007-01-01

    The nitrate radical (NO3) was first measured in the atmosphere in the 1970s and suggestions were made that it could play a major role in oxidising many unsaturated hydrocarbons, such as those emitted from the biosphere. Analysis of the hydrocarbon mix over the North Atlantic Ocean suggested

  7. Electrocatalytic reduction of nitrate at low concentration on coinage and transition-metal electrodes in acid solutions

    NARCIS (Netherlands)

    Dima, G.E.; Vooys, de A.C.A.; Koper, M.T.M.

    2003-01-01

    A comparative study was performed to determine the reactivity of nitrate ions at 0.1 M on eight different polycrystalline electrodes (platinum, palladium, rhodium, ruthenium, iridium, copper, silver and gold) in acidic solution using cyclic voltammetry (CV), chronoamperometry and differential

  8. Trends in concentrations of nitrate and total dissolved solids in public supply wells of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins, San Bernardino County, California: Influence of legacy land use

    Science.gov (United States)

    Kent, Robert; Landon, Matthew K.

    2013-01-01

    Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Forty-one of the 131 wells (31%) had a significant (p relations of nitrate trends to depth, lateral position, and VOCs imply that increasing nitrate concentrations are associated with nitrate loading from historical agricultural land use and that more recent urban land use is generally associated with lower nitrate concentrations and greater VOC occurrence. Increasing TDS trends were associated with relatively greater current nitrate concentrations and relatively greater amounts of urban land. Decreasing TDS trends were associated with relatively greater amounts of natural land use. Trends in TDS concentrations were not related to depth, lateral position, or VOC occurrence, reflecting more complex factors affecting TDS than nitrate in the study area.

  9. Energy-dispersive X-ray fluorescence analysis of cerium in ferrosilicon

    International Nuclear Information System (INIS)

    Marbec, E.R.

    1987-01-01

    The cerium was determined in ferrosilicon samples by energy-dispersive X-ray fluorescence techniques (XRF) techniques, with a secondary target of gadolinium. The methods employed were: comparison and linear regression with reference materials with cerium concentration between 0.4 and 1.0%. The samples were prepared in the form of pellets and the analytical results are reported as an average of five determinations with a confidence limits at 95% probability. (Author) [es

  10. Processing of Pakistani carbonatites for separation of cerium from adjacent rare earths

    International Nuclear Information System (INIS)

    Akram, M.; Qazi, N.K.; Khan, M.F.; Hasan, G.H.; Ahmed, N.; Chughtai, N.A.

    2003-01-01

    Carbonatite rock of Loe-Shilman area in North Western Frontier Province (NWFP) of Pakistan contains rare earth elements. This rock was upgraded in terms of its rare earths content from 2,000 ppm to 10,000 ppm rare earths oxide (REO) by crushing, calcination at 1000 deg. C for 3 hrs and cold leaching with 2% HCl for 1 hr. 80% to 95% of rare earths present in carbonatite powder were digested in nitric acid at 60 deg. C after 2 hrs stirring. Tributyl phosphate (TBP), diluted with dodecane, was used as extractant for extraction of rare earths. Since extraction is dependent on pH of the aqueous feed solution, the role of nitrate ions concentration in the solvent extraction of rare earth elements (REEs) was studied. It was observed that extraction of REEs was maximum at pH 1.1. The solvent had been unable to extract REEs from high acidic feed solutions. Solvents of different molarities were also tried against aqueous phase of pH 1.1. Studies showed a poor gain at 0 M and 0.5 M of organic phase while no gain observed beyond 2 molar solvent. 1 M organic phase gave maximum yield of rare earths salt, Ln(OH)/sub 3/, when stripped solution precipitated with ammonium hydroxide solution. It was also observed that if aqueous solution of 3.0 N was treated with blank solvent (i.e. Molarity = 0), it gave almost the same result. It was further established that optimum quantity of caging agent, Al(NO/sub 3/)/sub 3/-9H/sub 2/O added to aqueous solution prior to pH adjustment (i.e. 10 gm/100 gm powder dissolved) suppressed fluoride ions (F') which were hindering the extraction of rare earths. This improved the extraction efficiency of desired elements. To optimise the process parameters like solvent dilution, aqueous to organic ratio and extraction/stripping times, a' series of experiments were performed. Recovery for the desired elements had been between 78% to 86%. The optimum extraction parameters were found to be TBP concentration 40% (v/v) for aqueous to organic ratio 1:5 and 50

  11. Study on the uranium-cerium extraction and his application to the treatment of irradiated uranium

    International Nuclear Information System (INIS)

    Lobao, Afonso dos Santos Tome

    1979-01-01

    It was made a study on the behavior of uranium and cerium(IV) extraction, using the latter element as a plutonium simulator in a flowsheet of the treatment of irradiated uranium. Cerium(IV) was used under the same conditions as a plutonium in the Purex process because the admitted similar properties. An experimental work was initiated to determine the equilibrium curves of uranium, under the following conditions: concentration of 1 to 20 g U/1 and acidity varying from 1 to 5M in HNO 3 . Other parameters studied were the volumetric ratio of the phases and the influence of the concentration of TBP (tri-n-butyl phosphate). To guarantee the cerium(IV) extraction, the diluent (varsol) was previously treated with 10% potassium dichromate in perchloric acid, potassium permanganate in 1M sulphuric acid and concentrated sulphuric acid at 70 deg to eliminate reducing compounds. The results obtained for cerium extraction, allowed a better understanding of its behavior in solution. The results permitted to conclude that the decontamination for cerium are very high in the first Purex extraction cycle. The easy as cerium(IV) is reduced to the trivalent state contributes a great deal to its decontamination. (author)

  12. Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate; Aproveitamento de itrio e lantanio de um carbonato de terras raras de baixo teor em cerio, de um carbonato de itrio e de um oxido de terras itricas

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Mari Estela de

    2006-07-01

    In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

  13. Trends in Surface-Water Nitrate-N Concentrations and Loads from Predominantly-Forested Watersheds of the Chesapeake Bay Basin

    Science.gov (United States)

    Eshleman, K. N.

    2011-12-01

    Water quality monitoring data from streams and rivers provide the "gold standard" by which progress toward achieving real reductions in nutrient loadings to Chesapeake Bay must ultimately be assessed. The most recent trend results posted at the Chesapeake Bay Program (CBP) website reveal that a substantial percentage of tributaries are now showing long-term declines in flow-adjusted concentrations of nutrients and sediments: 22 sites showed statistically significant (p pollution controls for improved wastewater treatment plants and practices to reduce nutrients on farms and suburban lands, have reduced concentrations of nitrogen." But could this conclusion be pre-mature? I recently undertook a comparable analysis of long-term nitrate-N trends for a different group of watersheds (all located in the Chesapeake Bay watershed with long data records); this group includes nine watersheds that are predominantly (i.e., >75%) forested, plus five other Potomac River subwatersheds added for comparison. Based on comparable data and analytical methods to those used by CBP partners and USGS, 13 of the 14 sites-including both Potomac River stations (Chain Bridge at Washington DC and Hancock, Maryland)-showed statistically significant decreasing linear trends in annual flow-weighted nitrate-N concentration. Only one station-the heavily agricultural Upper Monocacy River-did not show a statistically significant (p RIM station could be entirely explained by commensurate improvements at the upstream (Hancock) station; in fact, no trend in nitrate-N concentration associated with the eastern portion of the basin was found (after subtracting out the influence of the upstream portion). Additional research is needed to understand why nitrogen retention by forested lands may be increasing and thus helping restore water quality throughout the Chesapeake Bay watershed. The results also have obvious implications for meeting local water quality goals as well as the basin-wide goal of the

  14. Application of composite materials based on various extractants for isolation of lanthanides(III) nitrates from multicomponent aqueous solutions

    International Nuclear Information System (INIS)

    Kopyrin, A.A.; Pyartman, A.K.; Kesnikov, V.A.; Pleshkov, M.A.; Exekov, M.H.

    1999-01-01

    In present work we obtained samples of composite materials mentioned containing tributylphosphate (TBP) and trialkylmethylammonium nitrate (TAMAN). Extraction of lanthanides(III) nitrates of cerium group from multicomponent aqueous solutions by means of these materials was studied. Some systems with different concentration of sodium nitrate up to 5 mol/l and the same systems containing additions of sodium chloride or sulfate along with sodium nitrate was investigated, isotherm of extraction being obtained for all cases. Also we compared in identical conditions extraction process when liquid extractants were used and process with composite materials. It was found that traditional extraction systems and systems based on composite extractants demonstrated almost the same extraction properties in respect to lanthanides(III) nitrates. Extraction isotherms observed in identical conditions and being shown in the same coordinates had no difference with taking into account errors of experiment. This fact allow to use the same mathematical model for those systems. For systems studied it was generated mathematical model that is able to describe extraction process when component concentration vary in wide range, with assumption being used that ratio activity coefficients in organic phase stay constant. (authors)

  15. Probability of Elevated Nitrate Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

    Science.gov (United States)

    Rupert, Michael G.; Plummer, Niel

    2009-01-01

    This raster data set delineates the predicted probability of elevated nitrate concentrations in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps was developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

  16. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Niroumandrad, S. [Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of); Rostami, M. [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of); Ramezanzadeh, B., E-mail: ramezanzadeh-bh@icrc.ac.ir [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of)

    2015-12-01

    Graphical abstract: - Highlights: • Flaky aluminum pigments were modified with cerium nitrate salt. • pH value of 3.0 was chosen as the optimized pH for the cerium solution. • Corrosion resistance of the pigment significantly increased after modification. • Alkaline pre-treatment prior to modification affected the cerium layer performance. - Abstract: The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce{sub 2}O{sub 3} and CeO{sub 2} was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  17. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    International Nuclear Information System (INIS)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-01-01

    Graphical abstract: - Highlights: • Flaky aluminum pigments were modified with cerium nitrate salt. • pH value of 3.0 was chosen as the optimized pH for the cerium solution. • Corrosion resistance of the pigment significantly increased after modification. • Alkaline pre-treatment prior to modification affected the cerium layer performance. - Abstract: The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce 2 O 3 and CeO 2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  18. In-situ irradiation of cerium precursors in TEM to study nanocrystal formation

    Science.gov (United States)

    Asghar, Muhammad Sajid Ali; Sabri, Mohammed Mohammed; Tian, Zijian; Möbus, Günter

    2017-09-01

    Three of the most commonly used precursor chemicals for wet-chemical nano-ceria synthesis are examined by means of direct dry electron irradiation in TEM. Transformation reactions of micron-size carbonate, chloride, and nitrate grains into nanocrystallites (internal or external) are recorded in situ. Progress of possible redox-changes of cerium is tracked by EELS. We find a straight local oxidation reaction for carbonates, but external nanorod formation by condensation in the case of chlorides, while nitrates show a multi-stage complex redox behaviour.

  19. Multifunctional cerium-based nanomaterials and methods for producing the same

    Science.gov (United States)

    O'Keefe, Matthew J.; Castano Londono, Carlos E.; Fahrenholtz, William G.

    2018-01-09

    Embodiments relate to a cerium-containing nano-coating composition, the composition including an amorphous matrix including one or more of cerium oxide, cerium hydroxide, and cerium phosphate; and crystalline regions including one or more of crystalline cerium oxide, crystalline cerium hydroxide, and crystalline cerium phosphate. The diameter of each crystalline region is less than about 50 nanometers.

  20. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, van M.; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp)3 scarcely dissolves

  1. Synthesis, characterization and antibacterial activity of hybrid chitosan-cerium oxide nanoparticles: As a bionanomaterials.

    Science.gov (United States)

    Senthilkumar, R P; Bhuvaneshwari, V; Ranjithkumar, R; Sathiyavimal, S; Malayaman, V; Chandarshekar, B

    2017-11-01

    The hybrid chitosan cerium oxide nanoparticles were prepared for the first time by green chemistry approach using plant leaf extract. The intense peak observed around 292nm in the UV-vis spectrum indicate the formation of cerium oxide nanoparticles. The XRD pattern revealed that the hybrid chitosan-cerium oxide nanoparticles have a polycrystalline structure with cubic fluorite phase. The FTIR spectrum of prepared samples showed the formation of Ce-O bonds and chitosan main chains COC and CO. The FESEM image of hybrid chitosan cerium oxide nanoparticles revealed that the particles are spherical in shape with grains size varying from 23.12nm to 89.91nm. EDAX analysis confirmed the presence of Ce, O, C and N elements in the prepared sample. TEM images showed that the prepared hybrid chitosan-cerium oxide nanoparticles are predominantly uniform in size and most of the particles are spherical in shape with less agglomeration and the particles size varies from 3.61nm to 24.40nm. The prepared chitosan cerium oxide nanoparticles of 50μL concentration showed good antibacterial properties against test pathogens, which was confirmed by the FESEM analysis. The prepared small particle size facilitate that these hybrid ChiCO 2 NPs could effectively be used in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A cerium(IV)-carbon multiple bond

    Energy Technology Data Exchange (ETDEWEB)

    Gregson, Matthew; Lu, Erli; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [Nottingham Univ. (United Kingdom). School of Chemistry

    2013-12-02

    Straightforward access to a cerium(IV)-carbene complex was provided by one-electron oxidation of an anionic ''ate'' cerium(III)-carbene precursor, thereby avoiding decomposition reactions that plague oxidations of neutral cerium(III) compounds. The cerium(IV)-carbene complex is the first lanthanide(IV)-element multiple bond and involves a twofold bonding interaction of two electron pairs between cerium and carbon. [German] Auf direktem Wege zu einem Cer(IV)-Carbenkomplex gelangt man durch die Einelektronenoxidation einer anionischen Carben-Cerat(III)-Vorstufe. So werden Zersetzungsprozesse vermieden, die die Oxidation neutraler Cer(III)-Verbindungen erschweren. Der Cer(IV)-Carbenkomplex enthaelt die erste Lanthanoid(IV)-Element-Mehrfachbindung; dabei binden Cer und Kohlenstoff ueber zwei Elektronenpaare.

  3. The development of a method for the simultaneous measurement of cerium (IV) and chromium (VI) species in nitric acid media - 16124

    International Nuclear Information System (INIS)

    Nickson, Ian D.; Boxall, Colin; Jackson, Angela; Whillock, Guy O.H.

    2009-01-01

    The corrosion of stainless steel in nitric acid media is a major concern for the nuclear industry. Several reprocessing schemes such as PUREX (Plutonium Uranium Reduction Extraction) and UREX (Uranium Reduction Extraction) utilise nitric acid media, and an understanding of the behaviour of key chemical species in these process streams is vital if their effect on associated corrosion reactions and their rates is to be accurately assessed and quantified. This will allow for more accurate prediction of the working lifetime of any stainless steel surface in contact with the process stream in question. Two such key species that are found in nuclear process streams are cerium as Ce (IV) and chromium as Cr(VI), both of which may act as corrosion accelerants. The redox chemistry of cerium and chromium in highly active liquor (HAL) will depend on nitrous acid concentration, temperature, acidity, total nitrate and possibly the influence of other dissolved species and hence an analytical technique for the on-line measurement of these quantities would be useful for lifetime prediction and corrosion prevention. As a result of this, a strategy for the simultaneous measurement of both Ce(IV) and Cr(VI) species in the presence of other ions typically found in process streams (such as Iron, Magnesium Neodymium and Aluminium) has been developed. The work presented will discuss the design and implementation of the electrochemical techniques that we have used in the development of this strategy and in the measurement of the species in question. (authors)

  4. Crystalline cerium(IV) phosphates

    International Nuclear Information System (INIS)

    Herman, R.G.; Clearfield, A.

    1976-01-01

    The ion exchange behaviour of seven crystalline cerium(IV) phosphates towards some of the alkali metal cations is described. Only two of the compounds (A and C) possess ion exchange properties in acidic solutions. Four others show some ion exchange characteristics in basic media with some of the alkali cations. Compound G does not behave as an ion exchanger in solutions of pH + , but show very little Na + uptake. Compound E undergoes ion exchange with Na + and Cs + , but not with Li+. Both Li + and Na + are sorbed by compounds A and C. The results are indicative of structures which show steric exclusion phenomena. (author)

  5. Contribution to the characterization of the ideality deviation of concentrated solutions of electrolytes: application to the case plutonium and uranium (IV) nitrates

    International Nuclear Information System (INIS)

    Charrin, N.

    1999-01-01

    The purpose of this work is to establish a base of binary data referring to the plutonium and uranium nitrates (IV) activity coefficients, which will permit to take account the medium effects in the process of liquid-liquid extraction set in action during the reprocessing of irradiated combustibles in a more scrupulous way. The first chapter sticks to establish the problematic of acquisition of actinides binary data at an oxidation state (IV) linked to two characteristics of this type of electrolyte its radioactive properties and its chemical properties. Its chemical properties bring us to define the fictitious binary data and to use an approach based on the thermodynamic concept of simple solutions, on the measurements of water activity of ternary or quaternary mixtures of the actinide, in nitric acid medium and on the binary data of nitric acid. The second chapter intended to propose reliable binary data concerning nitric acid. The validation of acquisition of fictitious binary data method suggested is undertaken. The electrolyte test is the thorium nitrate (IV). The very encouraging results has determined the carrying out of this work of research in that way. The third chapter is based on the experimental acquisition of uranium and plutonium nitrates (IV) binary data. It emphasises the importance given to the preparation of the studied mixtures which characteristics, very high actinide concentrations and low acidities, make them atypical solutions and without any referenced equivalents. The last chapter describes the exploitation which was made of the established binary data. The characteristic parameters of Pu(NO 3 ) 4 and U(NO 3 ) 4 of Pitzer model and of the specific interaction theory has been appraised. Then the application of' the concept of simple solutions to the calculation of the density or quaternary mixtures like Pu(NO 3 ) 4 / UO 2 (NO 3 ) 2 /HNO 3 / H 2 O was proposed. (author)

  6. System of ytterbium nitrate-hydrazine(mono-)dinitrate-water

    International Nuclear Information System (INIS)

    Khisaeva, D.A.; Katamanov, V.L.

    1986-01-01

    Solubility in ternary systems ytterbium nitrate-hydrazine monohydrate-water and ytterbium nitrate-hydrazine dinitrate-water is studied at 25 and 50 deg C. Salt components of both systems do not form with each other double addition compounds in the chosen temperature range. Initial salts are equilibrium solid phases of saturated solutions. Correlation of the range of primary crystallization of nitrate acydocomplexes of lanthanides formed in similar systems with their atomic number is considered. It is shown that hydrazine dinitrate can be used for separation of rare earth elements of cerium group

  7. Electrolytic technique for the chemical decontamination process with sulfuric acid-cerium (IV) for decommissioning

    International Nuclear Information System (INIS)

    Wei, Tsong-Yang; Hsieh, Jung-Chun.

    1992-01-01

    An electrolyzer with an ion-exchange membrane as the separator has been used to study the electrolytic redox reaction of Ce 4+ / Ce 3+ in sulfuric acid solution, which is a reagent for predismantling system decontamination. Influencing factors such as current density, cerium concentration, acidity, electrolyte flow rate, membrane type and electrode material were studied experimentally. The results indicate that the redox can be achieved with high conversion even as the cerium concentration is below 0.005 M. However, the current efficiency strongly depends on the cerium concentration. In addition, the acid content and the electrolyte flow rate show little influence on the redox reaction. Both cation and anion membrane are feasible for this process. Therefore, the operation conditions are widely applicable. Moreover, two different electrode materials, platinized titanium meshes and graphite, were used. The results show that the platinized titanium meshes is preferable to the graphite for higher current efficiency. (author)

  8. Influences of the main anodic electroplating parameters on cerium oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yang; Yang, Yumeng; Du, Xiaoqing; Chen, Yu [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhang, Zhao, E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); Zhang, Jianqing [Department of Chemistry, Zhejiang University, Hangzhou 310027, Zhejiang (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

    2014-06-01

    Cerium oxide thin films were fabricated onto 316 L stainless steel via a potentiostatically anodic electrodeposition approach in the solutions containing cerium(III) nitrate (0.05 M), ammonia acetate (0.1 M) and ethanol (10% V/V). The electrochemical behaviors and deposition parameters (applied potential, bath temperature, dissolving O{sub 2} and bath pH) have been investigated. Results show that, the electrochemical oxidation of Ce{sup 3+} goes through one electrochemical step, which is under charge transfer control. The optimum applied potential for film deposition is 0.8 V. Bath temperature plays a significant effect on the deposition rate, composition (different colors of the film) and surface morphology of the deposits. Due to the hydrolysis of Ce{sup 3+}, cerous hydroxide is facility to form when the bath temperature is higher than 60 °C. The electroplating bath pH is another key role for the anodic deposition of cerium oxide thin films, and the best bath pH is around 6.20. N{sub 2} or O{sub 2} purged into the bath will result in film porosities and O{sub 2} favors cerium oxide particles and film generation.

  9. The effects of cerium doping on the size, morphology, and optical properties of α-hematite nanoparticles for ultraviolet filtration

    Energy Technology Data Exchange (ETDEWEB)

    Cardillo, Dean [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Konstantinov, Konstantin, E-mail: konstan@uow.edu.au [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Devers, Thierry [Centre de Recherche sur la Matière Divisée, Institut de Physique, site de Chartres, Université d’Orléans (France)

    2013-11-15

    Highlights: • Possible application of cerium-doped α-hematite as ultraviolet filter. • Nanoparticles obtained through co-precipitation technique using various cerium doping levels followed by annealing. • Comprehensive materials characterisation utilizing XRD, DSC/TGA, STEM, UV–vis spectroscopy. • Increasing cerium content reduces particle sizing and alters morphology. • Solubility of cerium in hematite seen between 5 and 10% doping, 10% cerium doping greatly enhances attenuation in ultraviolet region and increases optical bandgap. - Abstract: Metal oxide nanoparticles have potential use in energy storage, electrode materials, as catalysts and in the emerging field of nanomedicine. Being able to accurately tailor the desirable properties of these nanoceramic materials, such as particle size, morphology and optical bandgap (E{sub g}) is integral in the feasibility of their use. In this study we investigate the altering of both the structure and physical properties through the doping of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with cerium at a range of concentrations, synthesised using a one-pot co-precipitation method. This extremely simple synthesis followed by thermal treatment results in stable Fe{sub 2−x}Ce{sub x}O{sub y} nanoceramics resulting from the burning of any unreacted precursors and transformation of goethite-cerium doped nanoparticle intermediate. The inclusion of Ce into the crystal lattice of these α-Fe{sub 2}O{sub 3} nanoparticles causes a significantly large reduction in mean crystalline size and alteration in particle morphology with increasing cerium content. Finally we report an increase optical semiconductor bandgap, along with a substantial increase in the ultraviolet attenuation found for a 10% Ce-doping concentration which shows the potential application of cerium-doped hematite nanocrystals to be used as a pigmented ultraviolet filter for cosmetic products.

  10. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Cerium Oxide Microspheres via the Internal Gelation Process

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Jack Lee [ORNL; Chi, Anthony [ORNL

    2009-02-01

    A simple test tube methodology was used to determine optimum process parameters for preparing hydrous cerium oxide microspheres via the internal gelation process.1 Broth formulations of cerium ammonium nitrate [(NH4)2Ce(NO3)6], hexamethylenetetramine, and urea were found that can be used to prepare hydrous cerium oxide gel spheres in the temperature range of 60 to 90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations to be able to equate the test-tube gelation times to actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broth formulations.

  11. Evaluating vertical concentration profile of carbon source released from slow-releasing carbon source tablets and in situ biological nitrate denitrification activity

    Science.gov (United States)

    Yeum, Y.; HAN, K.; Yoon, J.; Lee, J. H.; Song, K.; Kang, J. H.; Park, C. W.; Kwon, S.; Kim, Y.

    2017-12-01

    Slow-releasing carbon source tablets were manufactured during the design of a small-scale in situ biological denitrification system to reduce high-strength nitrate (> 30 mg N/L) from a point source such as livestock complexes. Two types of slow-releasing tablets, precipitating tablet (PT, apparent density of 2.0 g/mL) and floating tablet (FT), were prepared to achieve a vertically even distribution of carbon source (CS) in a well and an aquifer. Hydroxypropyl methylcellulose (HPMC) was used to control the release rate, and microcrystalline cellulose pH 101 (MCC 101) was added as a binder. The #8 sand was used as a precipitation agent for the PTs, and the floating agents for the FTs were calcium carbonate and citric acid. FTs floated within 30 min. and remained in water because of the buoyance from carbon dioxide, which formed during the acid-base reaction between citric acid and calcium carbonate. The longevities of PTs with 300 mg of HPMC and FTs with 400 mg of HPMC were 25.4 days and 37.3 days, respectively. We assessed vertical CS profile in a continuous flowing physical aquifer model (release test, RT) and its efficiency on biological nitrate denitrification (denitrification test, DT). During the RT, PTs, FTs and a tracer (as 1 mg rhodamine B/L) were initially injected into a well of physical aquifer model (PAM). Concentrations of CS and the tracer were monitored along the streamline in the PAM to evaluate vertical profile of CS. During the DT, the same experiment was performed as RT, except continuous injection of solution containing 30 mg N/L into the PAM to evaluate biological denitrification activity. As a result of RT, temporal profiles of CS were similar at 3 different depths of monitoring wells. These results suggest that simultaneous addition of PT and FT be suitable for achieving a vertically even distribution of the CS in the injection well and an aquifer. In DT, similar profile of CS was detected in the injection well, and nitrate was biologically

  12. Effect of pH and complementary ion concentration on nitrate removal using puroliteA400 Resin impregnated Cu in batch system

    Science.gov (United States)

    Turmuzi, M.; Tarigan, Z. N.; Nadapdap, L.; Batubara, F.

    2018-02-01

    The total nitrogen content in water bodies should be below 50 mg NO3 -/L (11.3 mgN/l) World Health Organization (WHO) 2006. The content of nitrogen exceeding the quality standard threshold will cause damage to the aquatic ecosystem and be carcinogenic to humans. The Purolite A-400 resin will be modified with Cu metal by batch method to see the adsorption allowance of nitrate in synthetic liquid waste with nitrate concentration of 50 mg/l. This study will evaluate the effect of pH and complementary ions on the adsorption process. From the result of the research, the second order pseudo model is the most suitable adsorption kinetics model. For the adsorption isotherms the most suitable model is the Freundlich adsorption isotherm model. The optimum pH conditions were at the range of 8.5. The addition of complementary ions sulfate and phosphate did not show any significant change, but sulfate is the most effective complementary ion with a content of 20 mg/l.

  13. Efeito da aplicação de nitrato na redução biogênica de sulfeto sob diferentes concentrações iniciais de bactérias redutoras de nitrato e sulfato Effect of nitrate application on reduction of biogenic sulphide under different initial concentrations of nitrate and sulphate-reducing bacteria

    Directory of Open Access Journals (Sweden)

    Kally Alves de Sousa

    2010-01-01

    Full Text Available The effect of sodium nitrate application in the reduction of biogenic sulphide was evaluated through a 2k complete factorial design, using as variable response the production of sulfide at intervals of incubation of 7, 14 and 28 days. The most effective condition for reducing the sulphide production (final concentrations from 0.4 to 1.6 mg S2- L-1 was obtained with an initial population of sulphate-reducing bacteria and nitrate-reducing bacteria of 10(4 MPN mL-1 and 427.5 mg L-1 nitrate. The results also suggested that the applications of nitrate to control the process of souring should follow a continuous scheme.

  14. Purification of alkali metal nitrates

    Science.gov (United States)

    Fiorucci, Louis C.; Gregory, Kevin M.

    1985-05-14

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

  15. Estimating nitrate concentrations in groundwater at selected wells and springs in the surficial aquifer system and Upper Floridan aquifer, Dougherty Plain and Marianna Lowlands, Georgia, Florida, and Alabama, 2002-50

    Science.gov (United States)

    Crandall, Christy A.; Katz, Brian G.; Berndt, Marian P.

    2013-01-01

    Groundwater from the surficial aquifer system and Upper Floridan aquifer in the Dougherty Plain and Marianna Lowlands in southwestern Georgia, northwestern Florida, and southeastern Alabama is affected by elevated nitrate concentrations as a result of the vulnerability of the aquifer, irrigation water-supply development, and intensive agricultural land use. The region relies primarily on groundwater from the Upper Floridan aquifer for drinking-water and irrigation supply. Elevated nitrate concentrations in drinking water are a concern because infants under 6 months of age who drink water containing nitrate concentrations above the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter as nitrogen can become seriously ill with blue baby syndrome. In response to concerns about water quality in domestic wells and in springs in the lower Apalachicola–Chattahoochee–Flint River Basin, the Florida Department of Environmental Protection funded a study in cooperation with the U.S. Geological Survey to examine water quality in groundwater and springs that provide base flow to the Chipola River. A three-dimensional, steady-state, regional-scale groundwater-flow model and two local-scale models were used in conjunction with particle tracking to identify travel times and areas contributing recharge to six groundwater sites—three long-term monitor wells (CP-18A, CP-21A, and RF-41) and three springs (Jackson Blue Spring, Baltzell Springs Group, and Sandbag Spring) in the lower Apalachicola–Chattahoochee–Flint River Basin. Estimated nitrate input to groundwater at land surface, based on previous studies of nitrogen fertilizer sales and atmospheric nitrate deposition data, were used in the advective transport models for the period 2002 to 2050. Nitrate concentrations in groundwater samples collected from the six sites during 1993 to 2007 and groundwater age tracer data were used to calibrate the transport aspect of the simulations

  16. Extraction-differential-photometric method to determine rare earths of cerium subgroup

    International Nuclear Information System (INIS)

    Askerov, D.N.; Gusejnov, I.K.; Melikov, A.A.

    1985-01-01

    The extraction - photometric method to determine great quantities of rare earths of the cerium subgroup as a complex with antipyrine A and diphenylguanidine is developed. Isobutyl and n-butyl alcohols are used as extractants. It is established that proportional dependence between relative optical density and concentration of rare earths of the cerium subgroup in the solution takes place in the concentration interval of 10.3-14.7 μg of rare earths in 1 ml of the solution. Determination error is+-1.12%. The technique is used to determine rare earths of the cerium subgroup in rare earth oxides of a mixed composition, as well as in monozite and loparite

  17. An investigation of the use of cerium and polyhedral oligomeric silsesquioxanes for the protection of polymeric epoxy compounds in the low Earth orbit environment

    Science.gov (United States)

    Piness, Jessica Miriam

    with the epoxy-amine matrix. A sedimented layer of the most incompatible POSS moiety was observed at the bottom of bars at the highest loading level of 5 wt% POSS. It was concluded that POSS could form a sedimented layer in this epoxy during cure. Epoxy amine materials containing POSS derivatives were tested by exposure to atomic oxygen at NASA Glenn Research Center with each POSS derivative present in separate samples at 2.5 wt% loading levels. Mass loss did not decrease against an unfilled control and glassification was not observed, leading to the conclusion that POSS could not be effectively concentrated at a surface to reduce degradation given the methods used. Taking this into account, the study transitioned into seeking ways to integrate highly UV absorbent cerium compounds with POSS. This part of the study is reported in Chapter IV. It was anticipated that POSS with a polar pendant group would interact through intermolecular forces with cerium (IV) oxide and produce a suspension that could be cured at the surface of polymers. However, in every experiment, the cerium (IV) oxide was not dispersed. However, a homogeneous dispersion of a cerium-containing compound was achieved by combining trisilanol phenyl POSS with cerium (III) nitrate hexahydrate. NMR and mass spectrometry showed that the mixture of Cerium nitrate and trisilanol phenyl POSS did not result in the formation of a chemical compound but FTIR studies indicated the presence of hydrogen bonding between the POSS silanols and cerium-associated water. The resulting material was termed "CePOSS". CePOSS was more UV absorbent in the UVc region than POSS or other cerium compounds as measured by solution UV-vis spectroscopy. In addition, CePOSS could be mixed into a POSS-epoxy coating, after pre-blending with poly(ethylene glycol) POSS, to produce films that were essentially opaque in the UV region below a wavelength of about 300 nm, and transparent in the visible region above 300 nm. The discovery of a 'window

  18. Altering properties of cerium oxide thin films by Rh doping

    International Nuclear Information System (INIS)

    Ševčíková, Klára; Nehasil, Václav; Vorokhta, Mykhailo; Haviar, Stanislav; Matolín, Vladimír

    2015-01-01

    Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO x thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO x thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffraction techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce 4+ and Ce 3+ and rhodium occurs in two oxidation states, Rh 3+ and Rh n+ . We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO x thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO x thin films leads to preparing materials with different properties

  19. Effects of structural and textural grain characteristics on leaching of sulphide minerals from a polymetallic concentrate by sodium nitrate and sulphuric acid solution

    Directory of Open Access Journals (Sweden)

    Sokić Miroslav D.

    2017-01-01

    Full Text Available In this paper, the influence of structural and textural characteristics of sulfide minerals on their leaching from a polymetallic concentrate by sulfuric acid and sodium nitrate solution is presented. The starting material was Pb–Zn–Cu sulphide polymetallic concentrate enriched during the flotation of a polymetallic ore in the "Rudnik" flotation plant (Rudnik – Serbia. Leaching experiments were carried out in a closed glass reactor, which provides stable hermetic conditions and allows heating at constant temperature. Chemical, XRD, qualitative and quantitative microscopic and SEM/EDX analyses were used to characterizes samples of the polymetallic concentrate and leach residue. It was determined that chalcopyrite, sphalerite, galena, pyrrhotite and quartz were present in the polymetallic concentrate. The content of sulphide minerals was 69.5%, of which 60.9% occurred as liberated grains: 88.3% of chalcopyrite, 59.3% of sphalerite, 25.1% of galena and 51.6% of pirrhotite. The rest of chalcopyrite, sphalerite, galena and pirrhotite grains were in the forms of inclusions, impregnations, and simple and complex intergrowths. During the leaching process by sodium nitrate and sulphuric acid solution, it was shown previously that the leaching rate of sulphide minerals decreased with time while a part of the sulphide minerals remained in the leach residue. After leaching at 80°C for 120 min, the yields were 69.8, 82.7 and 67.1% for Cu, Zn and Fe, respectively. Lead, in the form of insoluble anglesite, remained in the leach residue. In addition to the anglesite, unleached sulfide minerals and quartz, elemental sulfur was found in the solid residue. The content of sulphide minerals was 35% of which 33.7% minerals occur independently. In specific, 54.7% of chalcopyrite, 31.9% of sphalerite, 8.2% of galena and 37.6% of pyrrhotite appear as separate grains with highly corroded surfaces. Therefore, the structural assembly of sulphide grains in the

  20. Characterization of composite metal-ceramic of nickel-oxide cerium doped gadolinium

    International Nuclear Information System (INIS)

    Silva, M.L.A. da; Varela, M.C.R.S.

    2016-01-01

    Composite nickel doped cerium oxide are used in SOFC anode materials. In this study we evaluated the effect of the presence of gadolinium on the properties of composite nickel and ceria and. The supports were synthesized by sol-gel method. The impregnation with nickel nitrate was taken sequentially, followed by calcination. The materials were characterized by X-ray diffraction, measurement of specific surface area, temperature programmed reduction, Raman spectroscopy. The presence of gadolinium retained the fluorite structure of ceria by forming a solid solution, also not influencing significantly on the specific surface area of the support. On the other hand, there was a decrease in the area catalysts, which can be attributed to sintering of nickel. Furthermore, addition of gadolinium favored the formation of intrinsic and extrinsic vacancies in cerium oxide, which leads to an increase in the ionic conductivity of the solid, desirable property for an SOFC anode catalyst. (author)

  1. Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

    International Nuclear Information System (INIS)

    Ghosh, Swapankumar; Divya, Damodaran; Remani, Kottayilpadi C.; Sreeremya, Thadathil S.

    2010-01-01

    Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 o C. The activation energy for growth of CeO 2 nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO 2 particles in narrow size range. CeO 2 nanocrystals precipitated at 35 o C were further annealed at temperatures in the range 300-700 o C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

  2. Some Environmentally Relevant Reactions of Cerium Oxide

    Directory of Open Access Journals (Sweden)

    Janoš Pavel

    2014-12-01

    Full Text Available Reactive forms of cerium oxide were prepared by a thermal decomposition of various precursors, namely carbonates, oxalates and citrates, commercially available nanocrystalline cerium oxide (nanoceria was involved in the study for comparison. Scanning electron microscopy (SEM and x-ray diffraction analysis (XRD were used to examine the morphology and crystallinity of the samples, respectively, whereas the Brunauer-Emmett-Teller (BET method of nitrogen adsorption was used to determine surface areas. Interactions of cerium oxide with some phosphorus-containing compounds were investigated. Some of the examined samples, especially those prepared by annealing from carbonate precursors, exhibited an outstanding ability to destroy highly toxic organophosphates, such as pesticides (parathion methyl, or nerve agents (soman, VX. There were identified some relations between the degradation efficiency of cerium oxides and their crystallinity. It was also shown that cerium oxide is able to destroy one of widely used flame retardants - triphenyl phosphate. A phosphatase-mimetic activity of various cerium oxides was examined with the aid of a standardized phosphatase test.

  3. Modelling the future distribution of ammonium nitrate concentrations in The Netherlands for 2020: The sensitivity to meteorological parameters

    Science.gov (United States)

    Williams, J. E.; van der Swaluw, E.; de Vries, W. J.; Sauter, F. J.; van Pul, W. A. J.; Hoogerbrugge, R.

    2015-08-01

    We present a parameterization developed to simulate Ammonium particle (NH4+) concentrations in the Operational Priority Substances (OPS) source-receptor model, without the necessity of using a detailed chemical scheme. By using the ratios of the main pre-cursor gases SO2, NO2 and NH3, and utilising calculations performed using a chemical box-model, we show that the parameterization can simulate annual mean NH4+ concentration fields to within ∼15% of measured values at locations throughout the Netherlands. Performing simulations for different decades, we find a strong correlation of simulated NH4+ distributions for both past (1993-1995) and present (2009-2012) time periods. Although the total concentration of NH4+ has decreased over the period, we find that the fraction of NH4+ transported into the Netherlands has increased from around 40% in the past to 50% for present-day. This is due to the variable efficiency of mitigation practises across economic sectors. Performing simulations for the year 2020 using associated emission estimates, we show that there are generally decreases of ∼8-25% compared to present day concentrations. By altering the meteorological fields applied in the future simulations, we show that a significant uncertainty of between ∼50 and 100% exists on this estimated NH4+ distribution as a result of variability in the temperature dependent emission terms and relative humidity. Therefore, any projections of future NH4+ distributions should be performed using well chosen meteorological fields representing recent meteorological situations.

  4. LUMINESCENT PROPERTIES OF SILICATE GLASSES WITH CERIUM IONS AND ANTIMONY

    Directory of Open Access Journals (Sweden)

    A. M. Klykova

    2014-05-01

    Full Text Available The paper deals with the results of an experimental study of luminescence excitation spectra and luminescence of silicate glasses containing cerium ions and antimony. The aim of this work was to study the features of the luminescence and the effect of UV irradiation and heat treatment on luminescence and the state of cerium ions and antimony in glass. We investigated glass system Na2O-ZnO-Al2O3-SiO2-NaF-NaBr with additives CeO2 and Sb2O3. Synthesis was carried out in platinum crucibles in the air at 14500C. The samples were polished glass plates with a thickness of 0.5-1 mm. UV irradiation was carried out with a mercury lamp having a wide range of radiation in the spectral range 240-390 nm. It was conducted in a Nabertherm muffle furnaces. Luminescence spectra and excitation spectra were measured using a spectrofluorimeter MPF-44A (PerkinElmer at the room temperature. Measured luminescence spectra were corrected in view of the spectral sensitivity of the photodetector for spectrofluorimeter. Adjustment of the excitation spectra for the spectral dependence of the intensity of the excitation source was not carried out. During the experiments it was found that in silicate glasses Sb3+ ions can exist in two energy states, which corresponds to a different environment with oxygen ions. Heat treatment of these glasses in an oxidizing atmosphere leads to an increase in ion concentration of Sb3+ ions with a greater amount of oxygen in the environment. In glasses containing antimony and cerium ions, ultraviolet irradiation causes a change in the valence of cerium ions and antimony, which is accompanied by luminescence quenching. Subsequent heat treatment of glass leads to the inverse processes and restore luminescence excitation spectra. The study of fluorescent properties of silicate glasses with cerium and antimony ions led to the conclusion of the practical significance of this work. Promising multifunctional materials can be created on the basis of

  5. Catalysts with Cerium in a Membrane Reactor for the Removal of Formaldehyde Pollutant from Water Effluents

    Directory of Open Access Journals (Sweden)

    Mirella Gutiérrez-Arzaluz

    2016-05-01

    Full Text Available We report the synthesis of cerium oxide, cobalt oxide, mixed cerium, and cobalt oxides and a Ce–Co/Al2O3 membrane, which are employed as catalysts for the catalytic wet oxidation (CWO reaction process and the removal of formaldehyde from industrial effluents. Formaldehyde is present in numerous waste streams from the chemical industry in a concentration low enough to make its recovery not economically justified but high enough to create an environmental hazard. Common biological degradation methods do not work for formaldehyde, a highly toxic but refractory, low biodegradability substance. The CWO reaction is a recent, promising alternative that also permits much lower temperature and pressure conditions than other oxidation processes, resulting in economic benefits. The CWO reaction employing Ce- and Co-containing catalysts was carried out inside a slurry batch reactor and a membrane reactor. Experimental results are reported. Next, a mixed Ce–Co oxide film was supported on an γ-alumina membrane used in a catalytic membrane reactor to compare formaldehyde removal between both types of systems. Catalytic materials with cerium and with a relatively large amount of cerium favored the transformation of formaldehyde. Cerium was present as cerianite in the catalytic materials, as indicated by X-ray diffraction patterns.

  6. Growth Response Of Container Grown Japanese Azalea And Euonymus And Concentration Of Nitrates And Phosphates In The Runoff Water Under Different Irrigation And Fertilization

    Directory of Open Access Journals (Sweden)

    Matysiak Bożena

    2015-06-01

    Full Text Available In this study a growth response of two container-grown ornamentals (Euonymus japonicus ‘Ovatus Aureus’ and Rhododendron ‘Geisha Orange’ grown under different irrigation and fertilization rates was examined. The content of nitrogen (N and phosphorus (P in the plant leaves and in leachates was measured. Two levels of irrigation – standard irrigation (SI and – high irrigation rate (HI, and three control-release fertilizers (CRFs – Multicote 17-17-17, Osmocote Exact Standard 16-9-12 and Plantacote 15-10-15, applied at the rate of 1.5, 3.0 or 4.5 g·l−1, were applied. Fast-acting fertilizers were used as the control. HI adversely affected the growth and quality of Euonymus but stimulated the growth and increased quality of Rhododendron within two years of cultivation in relation to SI. There were no significant interactions between the irrigation and fertilization treatments; irrespective of water regimes, growth responses of both plant species to used fertilizers were similar. Osmocote and Plantacote at the rate of 3 g·l−1 were the most effective for the growth of Euonymus and Rhododendron plants, except of Euonymus in the second year, when 4.5 g·l−1 CRFs resulted in the best growth of plants. HI increased the amount of runoff water as well as N-NO3 and P-PO4 losses from containers during the entire growing period, irrespective of a fertilizer type. The amount of the nitrate and phosphate in leakage was higher when higher rates of CRFs were applied. Maximum nitrate concentration in leakage was the highest 14 days after the application of CRFs.

  7. Effect of Ni and Urea on Growth, Nitrate and Nutrients Concentration in Lettuce (Lactuca sativa Grown in Hydroponics

    Directory of Open Access Journals (Sweden)

    Hosein Nazari Mamaqani

    2017-02-01

    Full Text Available Introduction: The N source used in commercial hydroponic culture of vegetables is mainly NO3-N. The rate of NO3- uptake is usually high, particularly in leafy vegetables and it can be markedly increased when the NO3- supply in the environment is high. An abundant N supply leads to a high NO3-N absorption and accumulation in plants. When NO3- rich vegetables are consumed, various harmful effects on human health may occur such as met-hemoglobinemia (Blue Baby Syndrome and cancer. Keeping levels of NO3- below limits of FAO seems to be impossible without changing conventional fertilizer application techniques. The suitability of urea for the cultivation of field crops has been well documented. Urea is used as the main source of N fertilizer for crops grown in soil. Its use as N source for crops grown under the hydroponic system has yet to be evaluated. To hydrolyze urea, the enzyme urease requires Ni as a component. Substitution of urea for commonly used N03-N fertilizers in hydroponic culture of vegetables would not only enable to avoid excessive accumulation of N03- in plants but would also reduce the cost of production. Leafy vegetable crops, such as lettuce and spinach, contain large amounts of N03-N. Therefore, it is important to reduce N03- concentrations in hydroponically grown with lowest negative effects on yield. Materials and Methods: The experiments were carried outin greenhouse hydroponicsResearchFaculty of Agriculture, University of Tabriz in randomized complete block designwithtwo factors ureaatfivelevels of 0,25, 50, 75and100milligrams perliter(U0, U25,U50, U75, U100andnickelattwo levels of0and2mg per liter (Ni0, Ni2ofnickelsulfate(NiSO4in4replicatesusinglettuce(Lactuca sativa cv. Siyahoo. Plants fed with the modifiedHoagland solutionorhalf theconcentration. Treatments added to nutrient solution when plants were in four leaf stage. Plants were harvested 50 days after treatment. Different organs (leaves, stems and roots were separated

  8. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders prepared by the co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian-Chih [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Chen, Wen-Cheng [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Tien, Yin-Chun [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Shih, Chi-Jen, E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

    2010-04-30

    Cerium oxide nanocrystallites were synthesized by a co-precipitation process at a relatively low temperature, using cerium (III) nitrate as the starting material in a water solution with pH in the range of 8-9. The effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K, by XRD analysis. When calcined at temperatures from 473 to 1273 K, face-centered cubic phase crystallization was observed by XRD. The crystallite size of the cerium oxide increased from 12.0 to 48 nm as the calcining temperature increased from 473 to 1273 K, in the pH range 8-9. The activation energy for the growth of cerium oxide nanoparticles was found to have very low values of 17.5 kJ/mol for pH = 8 and 16.0 kJ/mol for pH = 9.

  9. Cerium sorption in grounds modified by anti-deflation treatment

    International Nuclear Information System (INIS)

    Firsova, L.P.; Bogatyrev, I.O.

    2001-01-01

    Influence of soils and grounds treatment by anti-deflation compositions on the size of the soil particles was studied. Under static conditions sorption of 144 Ce by turf-podsolic soils prior to an after their modification by the anti-deflation reagents, i.e. bitumens and insoluble in water polyelectrolytic complexes, was considered. Degrees of 144 Ce sorption in the soil-solution systems, depending on solutions pH, presence of alkali metal carbonates and cerium concentration, were determined [ru

  10. The concentration, source and deposition flux of ammonium and nitrate in atmospheric particles during dust events at a coastal site in northern China

    Science.gov (United States)

    Qi, Jianhua; Liu, Xiaohuan; Yao, Xiaohong; Zhang, Ruifeng; Chen, Xiaojing; Lin, Xuehui; Gao, Huiwang; Liu, Ruhai

    2018-01-01

    Asian dust has been reported to carry anthropogenic reactive nitrogen during transport from source areas to the oceans. In this study, we attempted to characterize NH4+ and NO3- in atmospheric particles collected at a coastal site in northern China during spring dust events from 2008 to 2011. Based on the mass concentrations of NH4+ and NO3- in each total suspended particle (TSP) sample, the samples can be classified into increasing or decreasing types. In Category 1, the concentrations of NH4+ and NO3- were 20-440 % higher in dust day samples relative to samples collected immediately before or after a dust event. These concentrations decreased by 10-75 % in the dust day samples in Categories 2 and 3. Back trajectory analysis suggested that multiple factors, such as the transport distance prior to the reception site, the mixing layer depth on the transport route and the residence time across highly polluted regions, might affect the concentrations of NH4+ and NO3-. NH4+ in the dust day samples was likely either in the form of ammonium salts existing separately to dust aerosols or as the residual of incomplete reactions between ammonium salts and carbonate salts. NO3- in the dust day samples was attributed to various formation processes during the long-range transport. The positive matrix factorization (PMF) receptor model results showed that the contribution of soil dust increased from 23 to 36 % on dust days, with decreasing contributions from local anthropogenic inputs and associated secondary aerosols. The estimated deposition flux of NNH4++NO3- varied greatly from event to event; e.g., the dry deposition flux of NNH4++NO3- increased by 9-285 % in Category 1 but decreased by 46-73 % in Category 2. In Category 3, the average dry deposition fluxes of particulate nitrate and ammonium decreased by 46 % and increased by 10 %, respectively, leading to 11-48 % decrease in the fluxes of NNH4++NO3-.

  11. Decomposition of metal nitrate solutions

    International Nuclear Information System (INIS)

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

    1982-01-01

    Oxides in powder form are obtained from aqueous solutions of one or more heavy metal nitrates (e.g. U, Pu, Th, Ce) by thermal decomposition at 300 to 800 deg C in the presence of about 50 to 500% molar concentration of ammonium nitrate to total metal. (author)

  12. Determination of free acid in highly concentrated organic and aqueous solutions of plutonium (IV) and uranium (VI) nitrate

    International Nuclear Information System (INIS)

    Wagner, J.F.; Lacour, J.L.

    1989-01-01

    Free acidity is an important parameter in the nuclear reprocessing control. The accuracy on the determination of free acidity is not really required in the nuclear reprocessing control itself but is necessary for certain types of analysis such as spectrophotometry (Pu (VI), Am (III),...), density determinations. A new titripotentiometric method for free acidity determination in concentrated U(VI) and Pu(IV) solutions is presented. This method is based on the complexing properties of dipicolinic acid (pyridine 2.6 dicarboxylic acid) and medium effect with H 2 O/DMSO mixture. This method can be used either in organic or aqueous phases with ratio /H + I/ metal ≥ 5.10 -2 and a relative standard deviation of 1%

  13. Climate control on sulphate and nitrate concentrations in alpine streams of Northern Italy along a nitrogen saturation gradient

    Directory of Open Access Journals (Sweden)

    M. Rogora

    2008-03-01

    Full Text Available The role of meteorology, hydrology and atmospheric deposition on the temporal pattern of SO4 and NO3 concentrations was investigated for three streams draining alpine catchments in Northern Italy.

    The study sites lie on a gradient of atmospheric fluxes of SO4 and NO3 (from about 50 to 80 meq m−2 y−1, and from 40 to 90 meq m−2 y−1, respectively. As a consequence of the increasing N input, the three catchments are also representative of aggrading levels of N saturation. Different methods of statistical analysis were applied to monthly data for the period 1997–2005 to identify which variables (temperature, precipitation, hydrology, SO4 and NO3 deposition were the main predictors of water chemistry and its change in time. Hydrological changes and snow cover proved to be the main confounding factors in the response to atmospheric deposition in the River Masino catchment. Its particular characteristics (small catchment area, rapid flushing during runoff and thin soil cover meant that this site responded without a significant delay to SO4 deposition decrease. It also showed a clear seasonal pattern of NO3 concentration, in response to hydrology and biological uptake in the growing season.

    The selected driving variables failed to model the water chemistry at the other study sites. Nevertheless, temperature, especially extreme values, turned out to be important in both SO4 and NO3 export from the catchments. This result might be largely explained by the effect of warm periods on temperature-dependent processes such as mineralization, nitrification and S desorption.

    Our findings suggest that surface waters in the alpine area will be extremely sensitive to a climate warming scenario: higher temperatures and increasing frequency of drought could exacerbate the effects

  14. Effect of cerium on structure modifications of a hybrid sol–gel coating, its mechanical properties and anti-corrosion behavior

    International Nuclear Information System (INIS)

    Cambon, Jean-Baptiste; Esteban, Julien; Ansart, Florence; Bonino, Jean-Pierre; Turq, Viviane; Santagneli, S.H.; Santilli, C.V.; Pulcinelli, S.H.

    2012-01-01

    Highlights: ► New sol–gel routes to replace chromates for corrosion protection of aluminum. ► Effect of cerium concentration on the microstructure of xerogel. ► Electrochemical and mechanical performances of hybrid coating with different cerium contents. ► Good correlation between the different results with an optimal cerium content of 0.01 M. -- Abstract: An organic–inorganic hybrid coating was developed to improve the corrosion resistance of the aluminum alloy AA 2024-T3. Organic and inorganic coatings derived from glycidoxypropyl-trimethoxysilane (GPTMS) and aluminum tri-sec-butoxide Al(O s Bu) 3 , with different cerium contents, were deposited onto aluminum by dip-coating process. Corrosion resistance and mechanical properties were investigated by electrochemical impedance measurements and nano-indentation respectively. An optimal cerium concentration of 0.01 M was evidenced. To correlate and explain the hybrid coating performances in relation to the cerium content, NMR experiments were performed. It has been shown that when the cerium concentration in the hybrid is higher than 0.01 M there are important modifications in the hybrid structure that account for the mechanical properties and anti-corrosion behavior of the sol–gel coating.

  15. Concentration of remote-handled, transuranic, sodium nitrate-based sludge using agitated thin-film evaporators

    International Nuclear Information System (INIS)

    Walker, J.F. Jr.; Youngblood, E.L.; Berry, J.B.; Pen, Ben-Li

    1991-01-01

    The Waste Handling and Packaging Plant (WHPP) is being designed at Oak Ridge National Laboratory (ORNL) to prepared transuranic waste for final disposal. Once operational, this facility will process, package, and certify remote-handled transuranic waste for ultimate shipment and disposal at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. One of the wastes that will be handled at WHIPP is the transuranic sludge currently stored at ORNL in eight 50,000-gal underground tanks. The use of an Agitated Thin-Film Evaporator (ATFE) for concentration of this waste is being investigated. Tests have shown that the ATFE can be used to produce a thick slurry, a powder, or a fused salt. A computer model developed at the Savannah River Plant (SRP) to simulate the operation of ATFE's on their waste is being modified for use on the ORNL transuranic sludge. This paper summarizes the results of the test with the ATFEs to date, discusses the changes in the SRP model necessary to use this model with the ORNL waste, and compares the results of the model with the actual data taken from the operation of ATFEs at vendors' test facilities. 8 refs., 1 fig., 3 tabs

  16. Specific Features of the Response of Cerium to Pulsed Actions

    Science.gov (United States)

    Atroshenko, S. A.; Zubareva, A. N.; Morozov, V. A.; Savenkov, G. G.; Utkin, A. V.

    2018-02-01

    Experimental studies of cerium at high rates and nanosecond durations of action have been performed. The isomorphic phase transition was studied upon shock compression. The spall strength of cerium has been determined. Cerium demonstrates anomalous compressibility upon dynamic loading. Stress waves dampen under action of a high-current electron beam due to the energy dissipation during fragmentation and twinning.

  17. Investigation of complexing of trivalent lanthanoids in aqueous nitrate solutions

    International Nuclear Information System (INIS)

    Kopyrin, A.A.; Proyaev, V.V.; Edinakova, V.

    1985-01-01

    Complexing of trivalent lanthanoids (Ce, Eu) with nitrate-ions in concentrated solutions of lithium and sodium nitrates has been studied in a wide range of ionic forces (1.0-7.0), using the extractional, densimetric and solubility methods. Nitrate complexes registered by the extraction and solubility methods mainly are of second sphere character. During rare earth extraction from concentrated nitrate solutions in the range of nitrate-ion concentrations <= 5 mol/l second sphere neutral nitrate complexes take part in distribution, at higher values of nitrate-ion concentration formation of intrasphere monoligand complexes of lanthanoids should be taken into account

  18. Nitrate glass

    International Nuclear Information System (INIS)

    Kirilenko, I.A.; Vinogradov, E.E.

    1977-01-01

    Experimental evidence on behaviour of nitrate glasses is reviewed in terms of relationships between the presence of water in vitrescent nitrate systems and the properties of the systems. The glasses considered belong to systems of Mg(NO 3 ) 2 - Nd(NO 3 ) 3 ; Hg(NO 3 ) 2 -Nd(NO 3 ) 3 ; NaNO 3 -Mg(NO 3 ) 2 -Nd(NO 3 ) 3 ; M-Zn(NO 3 ) 3 , where M is a mixture of 20% mass NaNO 3 and 80% mass Mg(NO 3 ) 2 , and Zn is a rare earth ion. Nitrate glass is shown to be a product of dehydration. Vitrification may be regarded as a resusl of formation of molecular complexes in the chain due to hydrogen bonds of two types, i.e. water-water, or water-nicrate group. Chain formation, along with low melting points of the nitrates, hinder crystallization of nitrate melts. Provided there is enough water, this results in vitrification

  19. Copolymerization of poly (ethylene oxide) and poly (methyl methacrylate) initiated by ceric ammonium nitrate

    International Nuclear Information System (INIS)

    Gomes, A.S.; Ferreira, A.A.; Coutinho, F.M.B.; Marinho, J.R.D.

    1984-01-01

    Cerium (IV) salts such as the ceric ammonium nitrate and ceric ammonium sulfate in aqueous acid solution with reducing agents such as alcohols, thiols, glycols, aldehydes and amines are well known initiators of vinyl polymerization. In this work, the polymerization of methyl methacrylate initiated by ceric ammonium nitrate/HNO 3 -poly(ethylene oxide) with hydroxyl end group system was studied in aqueous solution at 25 0 C to obtain block copolymers. (Author) [pt

  20. Potential denitrification rates of subsurface soil under paddy fields receiving ground water with high nitrate concentration; Konodo shosantai chisso gan`yu chikasui no ryunyusuru suiden kasodo ni okeru dacchitsu kassei

    Energy Technology Data Exchange (ETDEWEB)

    Toda, H [Shizuoka Agricultural Experiment Station, Shizuoka (Japan); Hidaka, S [Saitama Agricultural Experiment Station, Saitama (Japan)

    1996-02-10

    It is well known that the concentration of nitrate nitrogen in the surface water decreases as it flows downward in rice paddies irrigated with water high in nitrate nitrogen concentration. The decrease is attributed to absorption by rice plants and algae adherent thereto and denitrification in the reduction layer well developed in the rice paddy surface soil. In paddy fields downstream of the Kushibiki plateau in the northwestern part of Saitama Prefecture, it is occasionally observed that nitrate nitrogen concentration in the ground water decreases as it flows down (farther from the plateau) not only in the flooded period but also in the non-flooded period. This suggests that in the said paddy field denitrification takes place not only in the rice paddy surface layer soil but also in the lower layer soil. Under the circumstances, the denitrification rate in the rice paddy lower layer soil was measured using the acetylene inhibition method under anaerobic and added nitrate conditions. A denitrification rate of 0.4-46ngN/g{sup -1} wet soil/h{sup -1} was obtained from a 40-150cm deep layer soil, smaller by the order of 1-2 than that in the surface layer soil. This suggests that the lower layer soil contributes to denitrification. 17 refs., 3 figs., 1 tab.

  1. Exposure of cerium oxide nanoparticles to kidney bean shows disturbance in the plant defense mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanghamitra [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Bandyopadhyay, Susmita [Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Castillo-Michel, Hiram [European Synchrotron Radiation Facility, B.P. 220-38043 Grenoble, Cedex (France); Hernandez-Viezcas, Jose-Angel [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States); Sahi, Shivendra [Department of Biology, Western Kentucky University, Bowling Green, KY 42101 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN) (United States)

    2014-08-15

    Graphical abstract: - Highlights: • Kidney bean roots uptake nCeO{sub 2} primarily without biotransformation. • Cerium reached the root vascular tissues through gaps in the Casparian strip. • On longer exposure to high concentration, roots demonstrate stress response. • In leaves, guaiacol peroxidase plays a major role in ROS scavenging. - Abstract: Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO{sub 2}) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of ∼8 ± 1 nm nCeO{sub 2} (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO{sub 2} exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron μ-XRF mapping, and the chemical forms were identified using μ-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO{sub 2}, although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO{sub 2}/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO{sub 2} exposure in order to maintain cellular homeostasis.

  2. Mortality of nitrate fertiliser workers.

    Science.gov (United States)

    Al-Dabbagh, S; Forman, D; Bryson, D; Stratton, I; Doll, R

    1986-01-01

    An epidemiological cohort study was conducted to investigate the mortality patterns among a group of workers engaged in the production of nitrate based fertilisers. This study was designed to test the hypothesis that individuals exposed to high concentrations of nitrates might be at increased risk of developing cancers, particularly gastric cancer. A total of 1327 male workers who had been employed in the production of fertilisers between 1946 and 1981 and who had been occupationally exposed to nitrates for at least one year were followed up until 1 March 1981. In total, 304 deaths were observed in this group and these were compared with expected numbers calculated from mortality rates in the northern region of England, where the factory was located. Analysis was also carried out separately for a subgroup of the cohort who had been heavily exposed to nitrates--that is, working in an environment likely to contain more than 10 mg nitrate/m3 for a year or longer. In neither the entire cohort nor the subgroup was any significant excess observed for all causes of mortality or for mortality from any of five broad categories of cause or from four specific types of cancer. A small excess of lung cancer was noted more than 20 years after first exposure in men heavily exposed for more than 10 years. That men were exposed to high concentrations of nitrate was confirmed by comparing concentrations of nitrates in the saliva of a sample of currently employed men with control men, employed at the same factory but not in fertiliser production. The men exposed to nitrate had substantially raised concentrations of nitrate in their saliva compared with both controls within the industry and with men in the general population and resident nearby. The results of this study therefore weight against the idea that exposure to nitrates in the environment leads to the formation in vivo of material amounts of carcinogens. PMID:3015194

  3. Respiration of Nitrate and Nitrite.

    Science.gov (United States)

    Cole, Jeffrey A; Richardson, David J

    2008-09-01

    Nitrate reduction to ammonia via nitrite occurs widely as an anabolic process through which bacteria, archaea, and plants can assimilate nitrate into cellular biomass. Escherichia coli and related enteric bacteria can couple the eight-electron reduction of nitrate to ammonium to growth by coupling the nitrate and nitrite reductases involved to energy-conserving respiratory electron transport systems. In global terms, the respiratory reduction of nitrate to ammonium dominates nitrate and nitrite reduction in many electron-rich environments such as anoxic marine sediments and sulfide-rich thermal vents, the human gastrointestinal tract, and the bodies of warm-blooded animals. This review reviews the regulation and enzymology of this process in E. coli and, where relevant detail is available, also in Salmonella and draws comparisons with and implications for the process in other bacteria where it is pertinent to do so. Fatty acids may be present in high levels in many of the natural environments of E. coli and Salmonella in which oxygen is limited but nitrate is available to support respiration. In E. coli, nitrate reduction in the periplasm involves the products of two seven-gene operons, napFDAGHBC, encoding the periplasmic nitrate reductase, and nrfABCDEFG, encoding the periplasmic nitrite reductase. No bacterium has yet been shown to couple a periplasmic nitrate reductase solely to the cytoplasmic nitrite reductase NirB. The cytoplasmic pathway for nitrate reduction to ammonia is restricted almost exclusively to a few groups of facultative anaerobic bacteria that encounter high concentrations of environmental nitrate.

  4. Preparation and Characterization of Cerium (III Doped Captopril Nanoparticles and Study of their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Ghamami Shahriar

    2016-01-01

    Full Text Available In this research Ce3+ doped Captopril nanoparticles (Ce3+ doped CAP-NP were prepared by a cold welding process and have been studied. Captopril may be applied in the treatment of hypertension and some types of congestive heart failure and for preventing kidney failure due to high blood pressure and diabetes. CAP-NP was synthesized by a cold welding process. The cerium nitrate was added at a ratio of 10% and the optical properties have been studied by photoluminescence (PL. The synthesized compounds were characterized by Fourier transform infrared spectroscopy. The size of CAP-NP was calculated by X-ray diffraction (XRD. The size of CAP-NP was in the range of 50 nm. Morphology of surface of synthesized nanoparticles was studied by scanning electron microscopy (SEM. Finally the luminescence properties of undoped and doped CAP-NP were compared. PL spectra from undoped CAP-NP show a strong pack in the range of 546 nm after doped cerium ion into the captopril appeared two bands at 680 and 357 nm, which is ascribed to the well-known 5d–4f emission band of the cerium.

  5. Monte Carlo radiative transfer simulation of a cavity solar reactor for the reduction of cerium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Villafan-Vidales, H.I.; Arancibia-Bulnes, C.A.; Dehesa-Carrasco, U. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Col. Centro, A.P. 34, Temixco, Morelos 62580 (Mexico); Romero-Paredes, H. [Departamento de Ingenieria de Procesos e Hidraulica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No.186, Col. Vicentina, A.P. 55-534, Mexico D.F 09340 (Mexico)

    2009-01-15

    Radiative heat transfer in a solar thermochemical reactor for the thermal reduction of cerium oxide is simulated with the Monte Carlo method. The directional characteristics and the power distribution of the concentrated solar radiation that enters the cavity is obtained by carrying out a Monte Carlo ray tracing of a paraboloidal concentrator. It is considered that the reactor contains a gas/particle suspension directly exposed to concentrated solar radiation. The suspension is treated as a non-isothermal, non-gray, absorbing, emitting, and anisotropically scattering medium. The transport coefficients of the particles are obtained from Mie-scattering theory by using the optical properties of cerium oxide. From the simulations, the aperture radius and the particle concentration were optimized to match the characteristics of the considered concentrator. (author)

  6. The ytterbium nitrate-quinoline (piperidine) nitrate-water system

    International Nuclear Information System (INIS)

    Khisaeva, D.A.; Boeva, M.K.; Zhuravlev, E.F.

    1985-01-01

    Using the method of cross sections the solubility of solid phases in the ytterbium nitrate-quinoline nitrate - water (1) and ytterbium nitrate-piperidine nitrate-water (2) systems is studied at 25 and 50 deg C. It is established, that in system 1 congruently melting compound of the composition Yb(NO 3 ) 3 x2C 9 H 7 NxHNO 3 x3H 2 O is formed. The new solid phase has been isolated as a preparation and subjected to chemical X-ray diffraction, differential thermal and IR spectroscopic analyses. Isotherms of system 2 in the studied range of concentrations and temperatures consist of two branches, corresponding to crystallization of tetruaqueous ytterbi um nitrate and nitric acid piperidine

  7. Measurement of bulk etch rates for poly-allyl-diglycol carbonate (PADC) and cellulose nitrate in a broad range of concentration and temperature of NaOH etching solution

    International Nuclear Information System (INIS)

    Hermsdorf, D.; Hunger, M.; Starke, S.; Weickert, F.

    2007-01-01

    In the present work the dependence of the bulk etch rate v B for solid state nuclear track detectors (SSNTD) on the concentration c and the temperature T of the NaOH etching solution has been studied for material types PADC and cellulose nitrate. As commonly applied exponents of PADC and cellulose nitrate material, the commercial products CR-39 and LR-115 were investigated. The concentration and temperature have been varied in the ranges 0.5moll -1 -1 and 313 -1 and T between 313 and 333K for cellulose nitrate, respectively. The application of a simple Arrhenius-law of chemical reactions fails in the interpretation of the dependence on the concentration. A constant activation energy cannot describe the behaviour of v B (c,T) over the whole range of concentration. To understand the deviation, more qualified models treating the superposition of chemical and physical processes including reaction kinetics and material transport phenomena by diffusion have to be developed and tested

  8. Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.

    OpenAIRE

    Hernandez, D; Rowe, J J

    1987-01-01

    Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...

  9. Electrochemical redox processes involving soluble cerium species

    International Nuclear Information System (INIS)

    Arenas, L.F.; Ponce de León, C.; Walsh, F.C.

    2016-01-01

    Highlights: • The relevance of cerium in laboratory and industrial electrochemistry is considered. • The history of fundamental electrochemical studies and applications is considered. • The chemistry, redox thermodynamics and electrode kinetics of cerium are summarised. • The uses of cerium ions in synthesis, energy storage, analysis and environmental treatment are illustrated. • Research needs and development perspectives are discussed. - Abstract: Anodic oxidation of cerous ions and cathodic reduction of ceric ions, in aqueous acidic solutions, play an important role in electrochemical processes at laboratory and industrial scale. Ceric ions, which have been used for oxidation of organic wastes and off-gases in environmental treatment, are a well-established oxidant for indirect organic synthesis and specialised cleaning processes, including oxide film removal from tanks and process pipework in nuclear decontamination. They also provide a classical reagent for chemical analysis in the laboratory. The reversible oxidation of cerous ions is an important reaction in the positive compartment of various redox flow batteries during charge and discharge cycling. A knowledge of the thermodynamics and kinetics of the redox reaction is critical to an understanding of the role of cerium redox species in these applications. Suitable choices of electrode material (metal or ceramic; coated or uncoated), geometry/structure (2-or 3-dimensional) and electrolyte flow conditions (hence an acceptable mass transport rate) are critical to achieving effective electrocatalysis, a high performance and a long lifetime. This review considers the electrochemistry of soluble cerium species and their diverse uses in electrochemical technology, especially for redox flow batteries and mediated electrochemical oxidation.

  10. Evaluation of nitrate destruction methods

    International Nuclear Information System (INIS)

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

    1993-01-01

    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

  11. Correlation of the oxidation state of cerium in sol-gel glasses as a function of thermal treatment via optical spectroscopy and XANES studies.

    Science.gov (United States)

    Assefa, Zerihun; Haire, R G; Caulder, D L; Shuh, D K

    2004-07-01

    Sol-gel glass matrices containing lanthanides have numerous technological applications and their formation involves several chemical facets. In the case of cerium, its ability to exist in two different oxidation states or in mixed valence state provides additional complexities for the sol-gel process. The oxidation state of cerium present during different facets of preparation of sol-gel glasses, and also as a function of the starting oxidation state of cerium added, were studied both by optical spectroscopy and X-ray absorption near-edge structures (XANES). The findings acquired by each approach were compared. The primary focus was on the redox chemistries associated with sample preparation, gelation, and thermal treatment. When Ce3+ is introduced into the starting sols, the trivalent state normally prevails in the wet and room temperature-dried gels. Heating in air at >100 degrees C can generate a light yellow coloration with partial oxidation to the tetravalent state. Above 200 degrees C and up to approximately 1000 degrees C, cerium is oxidized to its tetravalent state. In contrast, when tetravalent cerium is introduced into the sol, both the wet and room temperature-dried gels lose the yellow-brown color of the initial ceric ammonium nitrate solution. When the sol-gel is heated to 110 degrees C it turns yellowish as the cerium tends to be re-oxidized. The yellow color is believed to represent the effect of oxidation and oligomerization of the cerium-silanol units in the matrix. The luminescence properties are also affected by these changes, the details of which are reported herein.

  12. Cerium, uranium, and plutonium behavior in glass-bonded sodalite, a ceramic nuclear waste form

    International Nuclear Information System (INIS)

    Lewis, M. A.; Lexa, D.; Morss, L. R.; Richmann, M. K.

    1999-01-01

    Glass-bonded sodalite is being developed as a ceramic waste form (CWF) to immobilize radioactive fission products, actinides, and salt residues from electrometallurgical treatment of spent nuclear reactor fuel. The CWF consists of about 75 mass % sodalite, 25 mass % glass, and small amounts of other phases. This paper presents some results and interpretation of physical measurements to characterize the CWF structure, and dissolution tests to measure the release of matrix components and radionuclides from the waste form. Tests have been carried out with specimens of the CWF that contain rare earths at concentrations similar to those expected in the waste form. Parallel tests have been carried out on specimens that have uranium or plutonium as well as the rare earths at concentrations similar to those expected in the waste forms; in these specimens UCl 3 forms UO 2 and PuCl 3 forms PuO 2 . The normalized releases of rare earths in dissolution tests were found to be much lower than those of matrix elements (B, Si, Al, Na). When there is no uranium in the CWF, the release of cerium is two to ten times lower than the release of the other rare earths. The low release of cerium may be due to its tetravalent state in uranium-free CWF. However, when there is uranium in the CWF, the release of cerium is similar to that of the other rare earths. This trivalent behavior of cerium is attributed to charge transfer or covalent interactions among cerium, uranium, and oxygen in (U,Ce)O 2

  13. Ammonium nitrate-potassium nitrate system

    Energy Technology Data Exchange (ETDEWEB)

    Cady, H.H.

    1981-01-01

    A portion of the binary phase diagram for the system ammonium nitrate-potassium nitrate has been determined from -55/sup 0/C to 185/sup 0/C. Results are presented for the ammonium-nitrate-rich end of the system up to 30 wt% potassium nitrate.

  14. Ecosystem and human health impacts from increased corn production: vulnerability assessment of exposure to high nitrate concentrations in groundwater and blue baby syndrome

    Science.gov (United States)

    Garcia, V.; Cooter, E. J.

    2013-12-01

    The Renewable Fuel Standard (RFS) requires oil refiners to reach a target of 15 billion gallons of corn-based ethanol by 2022. However, there are concerns that the broad-scale use of corn as a source of ethanol may lead to unintended economic and environmental consequences. This study applies the geophysical relationships captured with linked meteorological, air quality and agriculture models to examine the impact of corn production before enactment of the RFS in 2002 and at the height of the RFS targets in 2022. In particular, we investigate the probability of high-levels of nitrate in groundwater resulting from increased corn production and then relate this vulnerability to the potential for infants to acquire Methemoglobinemia, or 'Blue Baby Syndrome'. Blue Baby Syndrome (BBS) is a potentially fatal condition that occurs when the hemoglobin (Fe2+) in an infant's red blood cells is oxidized to methemoglobin (Fe3+), preventing the uptake of oxygen from the baby's blood. Exposure to high levels of nitrate in groundwater occur near the intersection of areas where surface water can more readily leach into shallow aquifers, wells are the main source of drinking water, and high nitrogen inputs exist. We use a coupled meteorological, agricultural and air quality model to identify areas vulnerable to increased nitrate contamination and associated risk to acquiring BBS. We first verify the relationship between predictive variables (e.g., nitrogen deposition and fertilization rates, landcover, soils and aquifer type) and nitrate groundwater levels by applying a regression model to over 800 nitrate measurements taken from wells located throughout the US (Figure 1). We then apply the regression coefficients to the coupled model output to identify areas that are at an increased risk for high nitrate groundwater levels in 2022. Finally, we examine the potential change in risk for acquiring BBS resulting from increased corn production by applying an Oral Reference Dose (Rf

  15. Nitrate photolysis in salty snow

    Science.gov (United States)

    Donaldson, D. J.; Morenz, K.; Shi, Q.; Murphy, J. G.

    2016-12-01

    Nitrate photolysis from snow can have a significant impact on the oxidative capacity of the local atmosphere, but the factors affecting the release of gas phase products are not well understood. Here, we report the first systematic study of the amounts of NO, NO2, and total nitrogen oxides (NOy) emitted from illuminated snow samples as a function of both nitrate and total salt (NaCl and Instant Ocean) concentration. We show that the release of nitrogen oxides to the gas phase is directly related to the expected nitrate concentration in the brine at the surface of the snow crystals, increasing to a plateau value with increasing nitrate, and generally decreasing with increasing NaCl or Instant Ocean (I.O.). In frozen mixed nitrate (25 mM) - salt (0-500 mM) solutions, there is an increase in gas phase NO2 seen at low added salt amounts: NO2 production is enhanced by 35% at low prefreezing [NaCl] and by 70% at similar prefreezing [I.O.]. Raman microscopy of frozen nitrate-salt solutions shows evidence of stronger nitrate exclusion to the air interface in the presence of I.O. than with added NaCl. The enhancement in nitrogen oxides emission in the presence of salts may prove to be important to the atmospheric oxidative capacity in polar regions.

  16. Effects of uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate, and citric acid on tomato plants

    International Nuclear Information System (INIS)

    Barrios, Ana Cecilia; Rico, Cyren M.; Trujillo-Reyes, Jesica; Medina-Velo, Illya A.; Peralta-Videa, Jose R.; Gardea-Torresdey, Jorge L.

    2016-01-01

    Little is known about the physiological and biochemical responses of plants exposed to surface modified nanomaterials. In this study, tomato (Solanum lycopersicum L.) plants were cultivated for 210 days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO_2, CA + nCeO_2) bulk cerium oxide (bCeO_2), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500 mg/kg, both the uncoated and CA + nCeO_2 increased shoot length by ~ 9 and ~ 13%, respectively, while bCeO_2 and CeAc decreased shoot length by ~ 48 and ~ 26%, respectively, compared with MPW (p ≤ 0.05). Total chlorophyll, chlo-a, and chlo-b were significantly increased by CA + nCeO_2 at 250 mg/kg, but reduced by bCeO_2 at 62.5 mg/kg, compared with MPW. At 250 and 500 mg/kg, nCeO_2 increased Ce in roots by 10 and 7 times, compared to CA + nCeO_2, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO_2 nor CA + nCeO_2 affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125 mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500 mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO_2 at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO_2 at 62.5 mg/kg produced higher total number of tomatoes, compared with control and the rest of the treatments. The surface coating reduced Ce uptake by roots but did not affect its translocation to the aboveground organs. In addition, there was no clear effect of surface coating on fruit production. To our knowledge, this is the first study comparing the effects of coated and uncoated nCeO_2 on tomato plants. - Highlights: • At 500 mg/kg, coated and bare NPs increased stem length by 13 and 9%, respectively. • Coated NPs at 500 mg/kg increased CAT activity in

  17. Cerium(III) pivalate [Ce(Piv)3(HPiv)3]2: synthesis, crystal structure, and thermal stability

    International Nuclear Information System (INIS)

    Khudyakov, M.Yu.; Kuz'mina, N.P.; Pisarevskij, A.P.; Martynenko, L.I.

    2002-01-01

    Complex [Ce(Piv) 3 (HPiv) 3 ] 2 was prepared by precipitation of cerium(III) nitrate aqueous solution with salt NH 4 (Piv) (HPiv = pivalic acid) and subsequent recrystallization from 5% HPiv solution in hexane. According to data of X-ray diffraction analysis and IR spectroscopy crystal structure of the complex is built of centrally symmetric dimers, in which cerium atoms are bound by four bridge pivalate ligands. Thermal analysis suggests that heating of the complex in nitrogen atmosphere results first in splitting off six HPiv molecules in the range of 90-190 deg C and then in thermolysis of Ce(Piv) 3 formed at 290-450 deg C. Sublimation of Ce(Piv) 3 occurs in the range of 290-350 deg C along with thermolysis during heating in vacuum (0.01 mm Hg), which permits preparing CeO 2 films by the method of chemical precipitation from gaseous phase [ru

  18. Studies of Some Lanthanide(III Nitrate Complexes of Schiff Base Ligands

    Directory of Open Access Journals (Sweden)

    Kishor Arora Mukesh Sharma

    2009-01-01

    Full Text Available The studies of 16 new lanthanide(III nitrate complexes of Schiff base ligands are discussed. Schiff bases were obtained by the condensation of 2–methyl–4–N,N–bis–2' –cyanoethyl aminobenzaldehyde with aniline and 3 different substituted anilines. Lanthanide(III nitrates, viz. gadolinium(III nitrate, lanthanum(III nitrate, samarium(III nitrate and cerium(III nitrate were chosen to synthesize new complexes. The complexes were characterized on the basis of physicochemical studies viz. elemental analysis, spectral, viz. IR and electronic spectral and magnetic studies. TGA studies of some of the representative complexes were also done. Some of the representative complexes were also screened for the anti microbial studies.

  19. Headspace Analysis of Ammonium Nitrate

    Science.gov (United States)

    2017-01-25

    explosive ammonium nitrate produces ammonia and nitric acid in the gaseous headspace above bulk solids, but the concentrations of the products have been...and NO2-, a product of nitrate fragmentation (Figure 7). Brief spikes in the background and dips in oxalic acid signal were observed at the time of...either filtered air or experimental nitric acid vapor sources so that analyte signal could be measured directly opposite background. With oxalic

  20. Negative feedback loops leading to nitrate homeostasis and oscillatory nitrate assimilation in plants and fungi.

    OpenAIRE

    Huang, Yongshun

    2011-01-01

    Master's thesis in Biological Chemistry Nitrate is an important nutrient for plants and fungi. For plants it has been shown that cytosolic nitrate levels are under homeostatic control. Here we describe two networks that can obtain robust, i.e. perturbation independent, homeostatic behavior in cytosolic nitrate concentration. One of the networks, a member in the family of outflow controllers, is based on a negative feedback loop containing a nitrate-induced activation of a controller molecu...

  1. Asymbiotic germination of mature seeds and protocorm development of Pseudorchis albida (Orchidaceae) are inhibited by nitrates even at extremely low concentrations

    Czech Academy of Sciences Publication Activity Database

    Ponert, J.; Figura, T.; Vosolsobě, S.; Lipavská, H.; Vohník, Martin; Jersáková, J.

    2013-01-01

    Roč. 91, č. 10 (2013), s. 662-670 ISSN 1916-2790 R&D Projects: GA ČR(CZ) GAP505/10/0786 Institutional support: RVO:67985939 Keywords : seed germination * nitrates * Pseudorchis albida Subject RIV: EF - Botanics Impact factor: 1.035, year: 2013

  2. Weather, landscape, and management effects on nitrate and soluble phosphorus concentrations in subsurface drainage discharge in the western Lake Erie basin

    Science.gov (United States)

    Subsurface drainage, while an important and necessary agricultural production practice in the Midwest, contributes nitrate (NO3) and soluble phosphorus (P) to surface waters. Eutrophication (i.e., excessive enrichment of waters by NO3 and soluble P) supports harmful algal blooms (HABs) in receiving ...

  3. Aminoethyl nitrate – the novel super nitrate?

    Science.gov (United States)

    Bauersachs, Johann

    2009-01-01

    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

  4. Obtainment of cerium dioxide for use as spectrochemical standard

    International Nuclear Information System (INIS)

    Silva Queiroz, C.A. da; Hespanhol, E.C.B.; Abrao, A.

    1992-01-01

    This paper describes a simple method for cerium separation and purification. Cerium is previously precipitated with N H 3 /air/H 2 O 2 system in a mixed chlorides solution obtained from Brazilian monazite treatment. The cerium fraction as cerium chloride is run down throughout a strong cationic resin bed and then the rare earth impurities separation is done by elution of the resin with separation ammonium salt of EDTA. None retainer ion is used in the purification technique by ion exchange. (author)

  5. Synthesis and structure of cerium nitrosocarbonylcyanmethanid complex

    International Nuclear Information System (INIS)

    Gerasimenko, H.; Scopenko, V.V.; Kapshuk, A.A.

    1998-01-01

    Full text: The complex compound [CeL 4 Dy 2 ]Na*2Ac (where L- nitrosocarbonylcyanmethanid, Dy -- dipyridile, Ac - acetone) were synthesised by interaction of cerium chloride and sodium nitrosocarbonylcyanmethanid from acetone solution. After two hours of mixing the dipyridil solution in acetone was added for complex stabilization. After filtration solution was put to desiccator for crystallisation. The complex was studied using IR- and UV-spectroscopy. The structure of the complex was determined using X-ray structure analysis. It was found that the structure of the complex belongs to orthorhombic Pna2(1) syngony with the unit cell parameters 17.010, 16.280 and 16.340Angstroms, respectively. It was found that cerium in the compound was eight co-ordinated. Four nitroso ligands were co-ordinated by bidentate bridge method and two dipyridiles by bidentate-cycle method

  6. Electrochemical reduction of cerium oxide into metal

    Energy Technology Data Exchange (ETDEWEB)

    Claux, Benoit [CEA, Valduc, F-21120 Is-sur-Tille (France); Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France); Serp, Jerome, E-mail: jerome.serp@cea.f [CEA, Valduc, F-21120 Is-sur-Tille (France); Fouletier, Jacques [Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France)

    2011-02-28

    The Fray Farthing and Chen (FFC) and Ono and Suzuki (OS) processes were developed for the reduction of titanium oxide to titanium metal by electrolysis in high temperature molten alkali chloride salts. The possible transposition to CeO{sub 2} reduction is considered in this study. Present work clarifies, by electro-analytical techniques, the reduction pathway leading to the metal. The reduction of CeO{sub 2} into metal was feasible via an indirect mechanism. Electrolyses on 10 g of CeO{sub 2} were carried out to evaluate the electrochemical process efficiency. Ca metal is electrodeposited at the cathode from CaCl{sub 2}-KCl solvent and reacts chemically with ceria to form not only metallic cerium, but also cerium oxychloride.

  7. Cerium and jojoba in engines?; Cerium et jojoba dans les moteurs?

    Energy Technology Data Exchange (ETDEWEB)

    Massy-Delhotel, E.

    1996-10-01

    The Belgium company CreaTel proposes a new system, called Forac, which can lead to a 10% reduction of fuel consumption in thermal engines together with a quasi-complete reduction of CO, HC, NOx pollutants and CO{sub 2} particulates emission. The system comprises a steam production device and an admission pipe with a cerium alloy whorl inside. The steam produced is mixed with the admission air and tears cerium particles from the inside of the admission pipe to the combustion chamber. The cerium particles act as a catalyst which favours the complete combustion of the fuel. The same company proposes also lubricant additives made from liquid jojoba wax which allow the reduction of pollutant emissions, fuel consumption and noise emissions of diesel engines. (J.S.)

  8. Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

    Science.gov (United States)

    Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

    2014-12-01

    Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Synthesis and ion-exchange properties of cerium(IV) molybdate

    International Nuclear Information System (INIS)

    Srivastava, S.K.; Raj Pal Singh; Sushma Agrawal; Satish Kumar

    1977-01-01

    The synthesis, ion exchange properties, and the separation of a number of cation pairs on the columns of cerium (IV) molybdate is discussed. In order to obtain the product in gel form showing a high exchange capacity and suitable for column operation, preliminary experiments were performed to determine the optimum conditions of precipitation, i.e., the concentration of ceric and molybdate solutions, mixing ratio, pH of precipitation and the order of mixing. Cerium (IV) molybdate, prepared under the optimum conditions of concentration, acidity etc., shows exchange capacity of 0.96 meg per g of exchanger. The sorption of a large number of metal ions has been investigated and the compound shows promising behaviour as cation exchanger. Numerous separations of analytical and radiochemical interest have been performed on the column of this exchanger with great efficiency. (T.G.)

  10. Synthesis and ion-exchange properties of cerium(IV) molybdate

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, S K; Singh, Raj Pal; Agrawal, Sushma; Kumar, Satish [Roorkee Univ. (India). Dept. of Chemistry

    1977-01-01

    The synthesis, ion exchange properties, and the separation of a number of cation pairs on the columns of cerium (IV) molybdate is discussed. In order to obtain the product in gel form showing a high exchange capacity and suitable for column operation, preliminary experiments were performed to determine the optimum conditions of precipitation, i.e., the concentration of ceric and molybdate solutions, mixing ratio, pH of precipitation and the order of mixing. Cerium (IV) molybdate, prepared under the optimum conditions of concentration, acidity etc., shows exchange capacity of 0.96 meg per g of exchanger. The sorption of a large number of metal ions has been investigated and the compound shows promising behaviour as cation exchanger. Numerous separations of analytical and radiochemical interest have been performed on the column of this exchanger with great efficiency.

  11. Lattice dynamics of α-cerium

    International Nuclear Information System (INIS)

    Smith, G.S.

    1985-01-01

    The lattice dynamics of the fcc α-phase of cerium metal was investigated using inelastic neutron scattering techniques. This phase of cerium is an example of a mixed-valent system. Various physical properties of α-Ce suggest that there may be coupling between the phonons and the f d transitions associated with the mixed valence phenomenon. These measurements of the dispersion curves provide important information about the electron-phonon interaction in this phase of cerium. These studies were not performed in the past because single crystals of α-Ce were not available. We were able to prepare a single α-Ce crystal using a high temperature, high pressure technique. The sample was of sufficient size for inelastic neutron scattering experiments, but the measurements were complicated because of the large mosaic spread (approx.7.0 0 ) of the crystal. It was possible, however, to obtain a set of dispersion curves along the [00zeta], [zeta,zeta,0], and [zeta,zeta,zeta] symmetry directions. Comparison of the dispersion curves with those of fcc γ-Ce indicate that the branches exhibit anomalous features that may be related to the mixed-valence effects

  12. Structure and activity of tellurium-cerium oxide acrylonitrile catalysts

    International Nuclear Information System (INIS)

    Bart, J.C.J.; Giordano, N.

    1982-01-01

    Ammoxidation of propylene to acrylonitrile (ACN) was investigated over various silica-supported (Te,Ce)O catalysts at 360 and 440 0 C. The binary oxide system used consists of a single nonstoichiometric fluorite-type phase α-(Ce,Te)O 2 up to about 80 mole% TeO 2 and a tellurium-saturated solid solution β-(Ce,Te)O 2 at higher tellurium concentrations. The ACN yield varies almost linearly with the tellurium content of (Ce,Te)O 2 . The β-(Ce,Te)O 2 phase is the most active component of the system (propylene conversion and ACN selectivity at 440 C of 76.7 and 74%, respectively) and is slightly more selective to ACN than α-Te0 2 . Tellurium reduces the overoxidation properties of cerium and selective oxidation occurs through Te(IV)-bonded oxygen

  13. Determination of Cerium (IV) Using Rhodamine 6G Fluorescence Quenching

    Science.gov (United States)

    Zhao, Zh.; Sheng, L.; Su, B.; Tao, C.; Jing, W.

    2017-11-01

    The interaction between rhodamine 6G (Rh6G) and cerium sulfate was studied by the fluorescence quenching method. In a sulfuric acid medium, the interaction of Ce(IV) with Rh6G results in Rh6G fluorescence quenching. The maximum excitation wavelength (λex) and the maximum emission wavelength (λem) are 530 nm and 555 nm, respectively. A good linearity between the relative fl uorescence intensity (ΔF) and Ce(IV) was observed in the range 0.12-1.08 μg/mL. The detection limit was 1.4 × 10-3 μg/mL. The optimum reaction conditions, influencing factors, and effect of coexisting substances were investigated in the experiment. We found that the concentration of Rh6G was 3.2 × 10-6 mol/L, and the fl uorescence intensity was maximum.

  14. Nanoporous cerium oxide thin film for glucose biosensor.

    Science.gov (United States)

    Saha, Shibu; Arya, Sunil K; Singh, S P; Sreenivas, K; Malhotra, B D; Gupta, Vinay

    2009-03-15

    Nanoporous cerium oxide (CeO(2)) thin film deposited onto platinum (Pt) coated glass plate using pulsed laser deposition (PLD) has been utilized for immobilization of glucose oxidase (GOx). Atomic force microscopy studies reveal the formation of nanoporous surface morphology of CeO(2) thin film. Response studies carried out using differential pulsed voltammetry (DPV) and optical measurements show that the GOx/CeO(2)/Pt bio-electrode shows linearity in the range of 25-300 mg/dl of glucose concentration. The low value of Michaelis-Menten constant (1.01 mM) indicates enhanced enzyme affinity of GOx to glucose. The observed results show promising application of the nanoporous CeO(2) thin film for glucose sensing application without any surface functionalization or mediator.

  15. Extraordinary superconductor with nearly trivalent cerium, CeCu2Si2

    International Nuclear Information System (INIS)

    Ishikawa, M.; Jaccard, D.; Jorda, J.-L.

    1982-01-01

    Concentrating on the ternary phase diagram, the authors have performed a complementary investigation on CeCu 2 Si 2 and confirm that the compound containing nearly trivalent cerium ions is a new type of superconductor with Tsub(c) around 0.5 K. The analyses of the upper critical field curve support the description of the compound by heavy fermion quasiparticles. Other particular features of this compound are also presented. (Auth.)

  16. Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles

    Science.gov (United States)

    Ten agronomic plant species were exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) (0, 250, 500 and 1000 mg/L) to examine potential effects on germination and early seedling development. We modified a standard test protocol develop...

  17. Nanoceria and bulk cerium oxide effects on the germination of asplenium adiantum-nigrum spores

    Directory of Open Access Journals (Sweden)

    Aranzazu Gomez-Garay

    2016-12-01

    Full Text Available Aim of study: The effect of cerium oxide engineered nanoparticles on the spore germination of the fern. Asplenium adiantum-nigrum. Area of study: France, Britanny Region, Finistére Department, Plougonvelin, in rocks near the sea. Material and methods: Asplenium spores were cultured in vitro on agar medium with Nano-CeO2 (less than 25 nm particle size and bulk-CeO2. The addition of each nano- and bulk particles ranged from 0 to 3000 mg L-1. Observations on rhizoidal and prothallial cells during first stages of gametophyte development were made. The No-Observed-Adverse-Effect concentration (NOAEC and Lowest-Observed-Adverse-Effect-Concentration (LOEC values for spore germination rate data were analyzed.  Main results: Germination was speeded up by 100 to 2000 mg L-1 nanoceria, while bulk cerium oxide had the same effect for 500 to 200 mg L-1 concentrations. Present results showed cellular damage in the protonema while rhizoid cells seemed not to be affected, as growth and membrane integrity remained. Research highlights: Both nanosized and bulk cerium oxide are toxic for the fern Asplenium adiantum-nigrum, although diverse toxicity patterns were shown for both materials. Diverse toxic effects have been observed: chloroplast membrane damage and lysis, cell wall and membrane disruption which leads to cell lysis; and alterations in morphology and development. Keywords: Nanoparticles; rhizoid; prothallus; chloroplast; fern.

  18. Nanoceria and bulk cerium oxide effects on the germination of asplenium adiantum-nigrum spores

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Garay, A.; Pintos, B.; Manzanera, J.A.; Prada, C.; Martin, L.; Gabriel y Galan, J.M.

    2016-07-01

    Aim of the study: The effect of cerium oxide engineered nanoparticles on the spore germination of the fern. Asplenium adiantum-nigrum. Area of study: France, Britanny Region, Finistére Department, Plougonvelin, in rocks near the sea. Material and methods: Asplenium spores were cultured in vitro on agar medium with Nano-CeO2 (less than 25 nm particle size) and bulk-CeO2. The addition of each nano- and bulk particles ranged from 0 to 3000 mg L-1. Observations on rhizoidal and prothallial cells during first stages of gametophyte development were made. The No-Observed-Adverse-Effect concentration (NOAEC) and Lowest-Observed-Adverse-Effect-Concentration (LOEC) values for spore germination rate data were analyzed. Main results: Germination was speeded up by 100 to 2000 mg L-1 nanoceria, while bulk cerium oxide had the same effect for 500 to 200 mg L-1 concentrations. Present results showed cellular damage in the protonema while rhizoid cells seemed not to be affected, as growth and membrane integrity remained. Research highlights: Both nanosized and bulk cerium oxide are toxic for the fern Asplenium adiantum-nigrum, although diverse toxicity patterns were shown for both materials. Diverse toxic effects have been observed: chloroplast membrane damage and lysis, cell wall and membrane disruption which leads to cell lysis; and alterations in morphology and development. (Author)

  19. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    International Nuclear Information System (INIS)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss; Sadaiyandi, Karuppasamy; Mahendran, Manickam; Sagadevan, Suresh

    2016-01-01

    Cerium oxide (CeO 2 ) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  20. Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, Devadoss Mangalam Durai Manoharadoss [Department of Physics, NPR College of Engineering and Technology, Natham, Dindigul, Tamil Nadu (India); Sadaiyandi, Karuppasamy [Department of Physics, Alagappa Government Arts College, Karaikudi, Sivaganga, Tamil Nadu (India); Mahendran, Manickam [Department of Physics, Thiagarajar College of Engineering, Madurai, Tamil Nadu (India); Sagadevan, Suresh, E-mail: duraiphysics2011@gmail.com [Department of Physics, AMET University (India)

    2016-03-15

    Cerium oxide (CeO{sub 2}) nanoparticles were prepared by the precipitation method. The average crystallite size of cerium oxide nanoparticles was calculated from the X-ray diffraction (XRD) pattern and found to be 11 nm. The FT-IR spectrum clearly indicated the strong presence of cerium oxide nanoparticles. Raman spectrum confirmed the cubic nature of the cerium oxide nanoparticles. The Scanning Electron Microscopy (SEM) analysis showed that the nanoparticles agglomerated forming spherical-shaped particles. The Transmission Electron Microscopic (TEM) analysis confirmed the prepared cerium oxide nanoparticles with the particle size being found to be 16 nm. The optical absorption spectrum showed a blue shift by the cerium oxide nanoparticles due to the quantum confinement effect. The dielectric properties of cerium oxide nanoparticles were studied for different frequencies at different temperatures. The dielectric constant and the dielectric loss of the cerium oxide nanoparticles decreased with increase in frequency. The AC electrical conductivity study revealed that the conduction depended on both the frequency and the temperature. (author)

  1. Soil organic matter influences cerium translocation and physiological processes in kidney bean plants exposed to cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanghamitra [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), El Paso, TX (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), El Paso, TX (United States); Trujillo-Reyes, Jesica [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Sun, Youping [Texas AgriLife Research Center at El Paso, Texas A& M University System, 1380 A & M Circle, El Paso, TX 79927 (United States); Barrios, Ana C. [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Niu, Genhua [Texas AgriLife Research Center at El Paso, Texas A& M University System, 1380 A & M Circle, El Paso, TX 79927 (United States); Margez, Juan P. Flores- [Autonomous University of Ciudad Juarez, Departamento de Química y Biología, Instituto de Ciencias Biomédicas, Anillo envolvente PRONAF y Estocolmo, Ciudad Juarez, Chihuahua 32310, México (Mexico); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Environmental Science and Engineering PhD Program, The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), El Paso, TX (United States)

    2016-11-01

    Soil organic matter plays a major role in determining the fate of the engineered nanomaterials (ENMs) in the soil matrix and effects on the residing plants. In this study, kidney bean plants were grown in soils varying in organic matter content and amended with 0–500 mg/kg cerium oxide nanoparticles (nano-CeO{sub 2}) under greenhouse condition. After 52 days of exposure, cerium accumulation in tissues, plant growth and physiological parameters including photosynthetic pigments (chlorophylls and carotenoids), net photosynthesis rate, transpiration rate, and stomatal conductance were recorded. Additionally, catalase and ascorbate peroxidase activities were measured to evaluate oxidative stress in the tissues. The translocation factor of cerium in the nano-CeO{sub 2} exposed plants grown in organic matter enriched soil (OMES) was twice as the plants grown in low organic matter soil (LOMS). Although the leaf cover area increased by 65–111% with increasing nano-CeO{sub 2} concentration in LOMS, the effect on the physiological processes were inconsequential. In OMES leaves, exposure to 62.5–250 mg/kg nano-CeO{sub 2} led to an enhancement in the transpiration rate and stomatal conductance, but to a simultaneous decrease in carotenoid contents by 25–28%. Chlorophyll a in the OMES leaves also decreased by 27 and 18% on exposure to 125 and 250 mg/kg nano-CeO{sub 2}. In addition, catalase activity increased in LOMS stems, and ascorbate peroxidase increased in OMES leaves of nano-CeO{sub 2} exposed plants, with respect to control. Thus, this study provides clear evidence that the properties of the complex soil matrix play decisive roles in determining the fate, bioavailability, and biological transport of ENMs in the environment. - Highlights: • Ce translocation to leaves was facilitated by higher organic matter (OM) in soil. • Lower soil OM increased leaf cover area in nano-CeO{sub 2} exposed plants. • Nano-CeO{sub 2} effects on metabolic processes were more

  2. Nitrates in surface waters, inputs and seasonality: Phase 2

    OpenAIRE

    Casey, H.; Clarke, R.T.; Smith, S.

    1988-01-01

    Changes in management practices and agricultural productivity over the past twenty years have lead to nitrate pollution and eutrophication of lakes and rivers. Information on nitrate concentrations and discharge has been collected on the River Frome at East Stoke since 1965, using the same analytical nitrate method so that the results are comparable. These records of weekly spot values of nitrate concentration and daily mean discharges have been analysed for trends and seasonal patterns in bo...

  3. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    Science.gov (United States)

    Lei, Li; Shi, Jing; Wang, Xin; Liu, Dan; Xu, Haigang

    2016-07-01

    The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Sisbnd Osbnd Si and Sisbnd Osbnd M chemical bonds. The optimum corrosion resistance of the coating in the corrosive media is obtained by 25 ml L-1 BTESPT modification. This whole study implies that the cerium conversion coating modified with certain silane agent deserves cautiousness before its application for corrosion resistance.

  4. Cerium(III-Selective Membrane Electrode Based on Dibenzo-24-crown-8 as a Neutral Carrier

    Directory of Open Access Journals (Sweden)

    Susheel K. Mittal

    2010-01-01

    Full Text Available Cerium(III-selective membrane electrodes have been prepared using dibenzo-24-crown-8 (DB24C8 as an electroactive material. A membrane having a composition: DB24C8 (4.5%, plasticizer (NPOE, 62.5% and PVC (33% gives the best performance. It works well over a wide Ce(III ion-concentration range of 1x10-5 M to 1x10-1 M with a Nernstian slope of 19.0 mV/decade and a detection limit of 3x10-5 M. It has a fast response time of 20 seconds and has an average lifetime of four months. The internal solution concentration does not have a significant effect on the response of the electrode except for a change in intercept of the calibration curves. The working pH range for Ce(III solutions (1x10-2 M and 1x10-3 M is 3.5-8.0. The proposed sensor shows a good selectivity for cerium(III with respect to alkali, alkaline earth, some transition and rare earth metal ions that are normally present along with cerium in its ores. The proposed sensor was investigated in partially non-aqueous media using acetone, methanol and DMSO mixtures with water. The electrode was further used as an indicator electrode for the potentiometric titration of Ce(III solution against oxalic acid solution.

  5. Bioavailability of cerium oxide nanoparticles to Raphanus sativus L. in two soils.

    Science.gov (United States)

    Zhang, Weilan; Musante, Craig; White, Jason C; Schwab, Paul; Wang, Qiang; Ebbs, Stephen D; Ma, Xingmao

    2017-01-01

    Cerium oxide nanoparticles (CeO 2 NP) are a common component of many commercial products. Due to the general concerns over the potential toxicity of engineered nanoparticles (ENPs), the phytotoxicity and in planta accumulation of CeO 2 NPs have been broadly investigated. However, most previous studies were conducted in hydroponic systems and with grain crops. For a few studies performed with soil grown plants, the impact of soil properties on the fate and transport of CeO 2 NPs was generally ignored even though numerous previous studies indicate that soil properties play a critical role in the fate and transport of environmental pollutants. The objectives of this study were to evaluate the soil fractionation and bioavailability of CeO 2 NPs to Raphanus sativus L (radish) in two soil types. Our results showed that the silty loam contained slightly higher exchangeable fraction (F1) of cerium element than did loamy sand soil, but significantly lower reducible (F2) and oxidizable (F3) fractions as CeO 2 NPs concentration increased. CeO 2 NPs associated with silicate minerals or the residue fraction (F4) dominated in both soils. The cerium concentration in radish storage root showed linear correlation with the sum of the first three fractions (r 2  = 0.98 and 0.78 for loamy sand and silty loam respectively). However, the cerium content in radish shoots only exhibited strong correlations with F1 (r 2  = 0.97 and 0.89 for loamy sand and silty loam respectively). Overall, the results demonstrated that soil properties are important factors governing the distribution of CeO 2 NPs in soil and subsequent bioavailability to plants. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  6. Cerium and yttrium oxide nanoparticles are neuroprotective

    International Nuclear Information System (INIS)

    Schubert, David; Dargusch, Richard; Raitano, Joan; Chan, S.-W.

    2006-01-01

    The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems

  7. Performance characteristics of silver cerium vanadate batteries

    OpenAIRE

    Arof , Abdul; Kamaluddin , Burhanuddin; Radhakrishna , S.

    1993-01-01

    Stoichiometric ratios of AR grade AgI, Ag2O, V2O5 and CeO2 were melted in a furnace and the melt was rapidly quenched to liquid nitrogen temperature to form a glass. The glassy nature of the sample has been confirmed by powder X-ray diffraction technique. The microstructure and microanalysis studies of the silver cerium vanadate (SCV) have been carried out by scanning electron microscopy (SEM) and energy dispersive analysis of X-rays (EDAX). The SEM micrograph of the as-quenched melt showed c...

  8. Ultrathin, epitaxial cerium dioxide on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Flege, Jan Ingo, E-mail: flege@ifp.uni-bremen.de; Kaemena, Björn; Höcker, Jan; Schmidt, Thomas; Falta, Jens [Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Bertram, Florian [Photon Science, Deutsches Elektronensynchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Wollschläger, Joachim [Department of Physics, University of Osnabrück, Barbarastraße 7, 49069 Osnabrück (Germany)

    2014-03-31

    It is shown that ultrathin, highly ordered, continuous films of cerium dioxide may be prepared on silicon following substrate prepassivation using an atomic layer of chlorine. The as-deposited, few-nanometer-thin Ce{sub 2}O{sub 3} film may very effectively be converted at room temperature to almost fully oxidized CeO{sub 2} by simple exposure to air, as demonstrated by hard X-ray photoemission spectroscopy and X-ray diffraction. This post-oxidation process essentially results in a negligible loss in film crystallinity and interface abruptness.

  9. Nitrates of rare earths

    International Nuclear Information System (INIS)

    Komissarova, L.N.; Pushkina, L.Ya.

    1984-01-01

    The systematization of experimental data with account of the last achievements in the field of studying the RE nitrate properties is realized. The methods of production, solubility in aqueous solutions structure, thermodynamic characteristics and thermal stability of nitrate hydrates, RE anhydrous and basic nitrates are considered. The data on RE nirtrate complexing in aqueous solutions are given. Binary nitrates, nitrate solvates and RE nitrate adducts with organic compounds are described. The use of RE nitrates in the course of RE production, in the processes of separation and fine cleaning of RE preparations is considered

  10. Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie; Divya, Damodaran [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India); Remani, Kottayilpadi C. [Sree Neelakanda Government Sanskrit College, Department of Chemistry (India); Sreeremya, Thadathil S. [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India)

    2010-06-15

    Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 {sup o}C. The activation energy for growth of CeO{sub 2} nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO{sub 2} particles in narrow size range. CeO{sub 2} nanocrystals precipitated at 35 {sup o}C were further annealed at temperatures in the range 300-700 {sup o}C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

  11. Nitrate metabolism in the gromiid microbial universe

    DEFF Research Database (Denmark)

    Høgslund, Signe; Risgaard-Petersen, Nils; Cedhagen, Tomas

    enclose and regulate a small biogeochemical universe within their cell. Their transparent proteinaceous cell wall surrounds a complex matrix consisting of sediment, bacteria and nitrate which is concentrated to hundreds of mM in the gromiid cell. The nitrate is respired to dinitrogen, but in contrast...

  12. Cerium oxide nanoparticles protect rodent lungs from hypobaric hypoxia-induced oxidative stress and inflammation

    Directory of Open Access Journals (Sweden)

    Arya A

    2013-11-01

    intraperitoneal injections of low micromole concentration, we successfully localized the nanoceria in rodent lung without any inflammatory response. The lung-deposited nanoceria limited ROS formation, lipid peroxidation, and glutathione oxidation, and prevented oxidative protein modifications like nitration and carbonyl formation during hypobaric hypoxia. We also observed reduced lung inflammation in the nanoceria-injected lungs, supporting the anti-inflammatory properties of nanoceria. Conclusion: Cumulatively, these results suggest nanoceria deposit in lungs, confer protection by quenching noxious free radicals during hypobaric hypoxia, and do not evoke any inflammatory response. Keywords: nanoceria, high altitude, nanomedicine

  13. Citric complexes of trivalent cerium and berkelium

    International Nuclear Information System (INIS)

    Boulhassa, S.

    1977-01-01

    The extraction by thenoyltrifluoroacetone (TTA) in benzene of trivalent cerium, berkelium and californium, at the indicator scale, hydrolysis and complexation by citric acid of these cations are studied. The radionuclides used were 144 Ce, 249 Bk and 249 Cf respectively γ, β and α emitters. The solvent extraction technique of the elements by TTA in benzene from a perchloric medium at the ionic stength 0.1 was employed. The distribution coefficients D were measured by the γ, β or α radiometry. Cerium and berkelium, which have a comparable redox behavior, show in solution a relatively stable valency IV. Therefore the study by solvent extraction of their trivalent form required the standing up of complete reducing conditions of these elements and their stabilization in solution at the valency III. The thermodynamic data obtained for berkelium and californium contribute to understand the chemistry of these elements and permit to complete the third 'tetrad branch' of 5f elements from Cm 3+ to Es 3+ . This tetrad effect is a manifestation of thermodynamic consequence of the 'nephelauxetic effect'. As for Ce(III), the data confirm the pronounced acid property and may be show no neglected ligand effect for f 1 configuration [fr

  14. The behaviour of ozone and peroxyacetyl nitrate concentrations for different wind regimes during the MEDCAPHOT-TRACE campaign in the greater area of Athens, Greece

    DEFF Research Database (Denmark)

    Suppan, P.; Fabian, P.; Vyras, L.

    1998-01-01

    As a part of an international experimental field campaign, the association of air pollution with sea breeze circulation in the Greater Athens Area (GAA) is discussed on the basis of the behaviour of ozone and peroxyacetyl nitrate (PAN). During typical sea breeze days inside the Athens basin the o...... a straight line across the Athens basin ranging From the island of Aegina in the Gulf of Saronikos to the northern border of the GAA show distinct peaks due to the pollution cloud NEPHOS. (C) 1998 Published by Elsevier Science Ltd. All rights reserved....... the ozone levels reach values up to 66% greater than values outside the basin. There is also an increase in ozone and PAN mixing ratios from the south to the north and from lower to higher locations, within the GAA. On-line PAN-measurements with a time resolution of 5 min at three sites located almost along...

  15. Effects of uncoated and citric acid coated cerium oxide nanoparticles, bulk cerium oxide, cerium acetate, and citric acid on tomato plants

    Energy Technology Data Exchange (ETDEWEB)

    Barrios, Ana Cecilia [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Rico, Cyren M. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Trujillo-Reyes, Jesica [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Medina-Velo, Illya A. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Peralta-Videa, Jose R. [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States); Gardea-Torresdey, Jorge L., E-mail: jgardea@utep.edu [Department of Chemistry, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Environmental Science and Engineering Ph.D. Program, The University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); University of California Center for Environmental Implications of Nanotechnology (UC CEIN), The University of Texas at El Paso, 500 West University Ave., El Paso, TX 79968 (United States)

    2016-09-01

    Little is known about the physiological and biochemical responses of plants exposed to surface modified nanomaterials. In this study, tomato (Solanum lycopersicum L.) plants were cultivated for 210 days in potting soil amended with uncoated and citric acid coated cerium oxide nanoparticles (nCeO{sub 2}, CA + nCeO{sub 2}) bulk cerium oxide (bCeO{sub 2}), and cerium acetate (CeAc). Millipore water (MPW), and citric acid (CA) were used as controls. Physiological and biochemical parameters were measured. At 500 mg/kg, both the uncoated and CA + nCeO{sub 2} increased shoot length by ~ 9 and ~ 13%, respectively, while bCeO{sub 2} and CeAc decreased shoot length by ~ 48 and ~ 26%, respectively, compared with MPW (p ≤ 0.05). Total chlorophyll, chlo-a, and chlo-b were significantly increased by CA + nCeO{sub 2} at 250 mg/kg, but reduced by bCeO{sub 2} at 62.5 mg/kg, compared with MPW. At 250 and 500 mg/kg, nCeO{sub 2} increased Ce in roots by 10 and 7 times, compared to CA + nCeO{sub 2}, but none of the treatments affected the Ce concentration in above ground tissues. Neither nCeO{sub 2} nor CA + nCeO{sub 2} affected the homeostasis of nutrient elements in roots, stems, and leaves or catalase and ascorbate peroxidase in leaves. CeAc at 62.5 and 125 mg/kg increased B (81%) and Fe (174%) in roots, while at 250 and 500 mg/kg, increased Ca in stems (84% and 86%, respectively). On the other hand, bCeO{sub 2} at 62.5 increased Zn (152%) but reduced P (80%) in stems. Only nCeO{sub 2} at 62.5 mg/kg produced higher total number of tomatoes, compared with control and the rest of the treatments. The surface coating reduced Ce uptake by roots but did not affect its translocation to the aboveground organs. In addition, there was no clear effect of surface coating on fruit production. To our knowledge, this is the first study comparing the effects of coated and uncoated nCeO{sub 2} on tomato plants. - Highlights: • At 500 mg/kg, coated and bare NPs increased stem length by 13 and 9

  16. Cerium chloride stimulated controlled conversion of B-to-Z DNA in self-assembled nanostructures

    International Nuclear Information System (INIS)

    Bhanjadeo, Madhabi M.; Nayak, Ashok K.; Subudhi, Umakanta

    2017-01-01

    DNA adopts different conformation not only because of novel base pairs but also while interacting with inorganic or organic compounds. Self-assembled branched DNA (bDNA) structures or DNA origami that change conformation in response to environmental cues hold great promises in sensing and actuation at the nanoscale. Recently, the B-Z transition in DNA is being explored to design various nanomechanical devices. In this communication we have demonstrated that Cerium chloride binds to the phosphate backbone of self-assembled bDNA structure and induce B-to-Z transition at physiological concentration. The mechanism of controlled conversion from right-handed to left-handed has been assayed by various dye binding studies using CD and fluorescence spectroscopy. Three different bDNA structures have been identified to display B-Z transition. This approach provides a rapid and reversible means to change bDNA conformation, which can be used for dynamic and progressive control at the nanoscale. - Highlights: • Cerium-induced B-to-Z DNA transition in self-assembled nanostructures. • Lower melting temperature of Z-DNA than B-DNA confirmed by CD spectroscopy. • Binding mechanism of cerium chloride is explained using fluorescence spectroscopy. • Right-handed to left-handed DNA conformation is also noticed in modified bDNA structure.

  17. Indirect flow injection determination of N-acetyl-L-cysteine using cerium(IV) and ferroin

    International Nuclear Information System (INIS)

    Vieira, Heberth Juliano; Fatibello-Filho, Orlando

    2005-01-01

    An indirect flow injection spectrophotometric procedure is proposed for the determination of N-acetyl-L-cysteine in pharmaceutical formulations. In this system, ferroin ([Fe(II)-(fen) 2 ] 2+ ) in excess, with a strong absorption at 500 nm, is oxidized by cerium(IV) yielding cerium(III) and [Fe(III)-(fen) 2 ] 3+ (colorless), thus producing a baseline. When N-acetyl-L-cysteine solution is introduced into the flow injection system, it reacts with cerium(IV) increasing the analytical signal in proportion to the drug concentration. Under optimal experimental conditions, the linearity of the analytical curve for N-acetyl-L-cysteine ranged from 6.5x10 -6 to 1.3x10 -4 mol L -1 . The detection limit was 5.0x10 -6 mol L -1 and recoveries between 98.0 and 106% were obtained. The sampling frequency was 60 determinations per hour and the RSD was smaller than 1.4% for 2.2x10 -5 mol L -1 N-acetyl-L-cysteine. (author)

  18. Electrochemical separation of cerium and yttrium in molten chlorides on liquid-metallic electrodes

    International Nuclear Information System (INIS)

    Yamshchikov, L.F.; Lebedev, V.A.; Nichkov, I.F.

    1978-01-01

    An estimating calculation of the coefficients of separation of cerium and yttrium in the process of electrolysis in molten salts on liquid electrodes of aluminium, gallium, indium, lead, tin, antimonium and zinc is carried out. The calculation of the separation coefficients was carried out according to the known values of activation coefficients of cerium and yttrium in fusible metals. The electrolysis was carried out at 973 K in the argon air in the cell with an eutectic mixture of NaCl and KCl as an elactrolyte. It is shown that the salten phase is concentrated by yttrium, and the melallic one- by cerium on all the electrodes. The value of the separation coefficient of Ce and Y is considerably high and continuously increases on the fusible metals in the Zn, In, Ga, Al, Pb, Sn, Sb series. The experimental values of the separation coefficients practically coincide with the theoretically calculated ones, testifying to the possibility of the effective separation of elements even in a single-staged possibility of the effective separation of elements even in a single-staged process. An electrolysis of molten salts is not inferior in its selectivity to the universally recognized methods of the fine purification of substances permitting to separate Ce and Y with the Ksub(sep) approximately equal to 10

  19. One-step synthesis and characterizations of cerium oxide nanoparticles in an ambient temperature via Co-precipitation method

    Science.gov (United States)

    Pujar, Malatesh S.; Hunagund, Shirajahammad M.; Desai, Vani R.; Patil, Shivaprasadgouda; Sidarai, Ashok H.

    2018-04-01

    We report the simple Co-precipitation method for the synthesis of Cerium oxide (CeO2) nanoparticles (NPs) in an ambient temperature. We have taken the Cerium (III) nitrate hexahydrate (Ce(NO3)3.6H2O) and Sodium hydroxide (NaOH) as the precursors. The obtained NPs were analyzed using the UV-Vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The obtained results signify that UV-Vis spectrum exhibited a well-defined absorption peak at 274 nm and the estimated energy gap (Eg) is 4.05 eV. The FT-IR analysis provides the supporting evidence for the presence of bonding of O-H, nitrates, alcohols and O-Ce-O vibrations. The XRD result reveals that the synthesized CeO2 NPs was crystallite with cubic phase structure and the estimated average crystallite size of CeO2 NPs using Scherer's and W-H method was significantly different due to their assumptions. Further, it is purposed to study their photocatalytic biological activities.

  20. Investigation of AA2024-T3 surfaces modified by cerium compounds: A localized approach

    International Nuclear Information System (INIS)

    Paussa, L.; Andreatta, F.; De Felicis, D.; Bemporad, E.; Fedrizzi, L.

    2014-01-01

    Highlights: •The precipitation of cerium compounds occurs on the entire AA2024-T3 surface. •The matrix is less involved in the cerium precipitation. •Cerium intensely precipitates on Mg-rich IM particles. •The electrochemical behavior of Mg-rich IM particles influences the mechanism of cerium precipitation. -- Abstract: The precipitation of cerium compounds on polished AA2024-T3 surfaces was investigated following an electrochemical and microstructural localized approach. It was found that cerium precipitation occurs on the entire surface covering intermetallic particles and the matrix as well. The matrix is the region where the precipitation of cerium is less favoured. The highest amount of cerium was observed on magnesium-rich intermetallic particles. The localized analyses suggest that precipitation of cerium on magnesium-rich intermetallic particles could happen following two mechanisms: the former based on a potential reversal of the intermetallic particles and the latter due to a partial magnesium dissolution

  1. Characterization of platinized and unplatinized cerium dioxide and other cerium containing catalyst supports

    International Nuclear Information System (INIS)

    Daniel, D.W.

    1984-01-01

    The adsorption of CO on platinized cerium dioxide has been investigated by FTIR (Fourier Transform Infrared Spectroscopy). Four active surface sites and two adsorption geometries were found for the oxidized catalyst. Although the metallic sites and both geometries, linear and bridged, were retained upon reduction the two cationic sites were not. During stepwise desorption, CO dissociates leaving behind adsorbed carbon inhibiting readsorption. At elevated temperatures CeO 2 oxidizes Pt. The large decrease in CO adsorption resulting from high temperature reduction was reversed by reoxidation. XPS (X-ray Photoelectron Spectroscopy) data provided no evidence of encapsulation and XRD (X-ray Diffraction) showed the retention of a constant particle size. The results were interpreted as electronic metal-support interaction. The addition of H 2 or D 2 to adsorbed CO at 25 0 C caused spillover of the CO onto the support and a decrease in CO band frequency. When O 2 was added to preadsorbed CO a new band associated with oxygen and CO coadsorbed on a single Pt atom appeared. Carbon dioxide dissociation at room temperature is proposed to occur via a Langmuir-Hinshelwood mechanism. CO adsorption on platinized titania, silica, ceria/titania, ceria/silica, and cerium titanate has also been studied by the same techniques. The adsorption/desorption behavior of the cerium/titania and the single oxide systems paralleled that of Pt/CeO 2

  2. Bordoni relaxation and magnetic transformation in cerium and cerium-lanthanum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Postnikov, V S; Polner, G L; Sharshakov, I M

    1975-11-01

    The internal friction in pure cerium and cerium-base alloys with 2.5 and 12 weight percent of lanthanum added at temperature ranging from 4.2 deg up to 77/sup 0/K is described. Amplitude-independent internal friction has been measured with an inverse torsion pendulum with a specimen oscillation frequency of 1-30 hz in vacuum not less than 1.10/sup -5/ torr. A temperature of the specimen has been determined with a capacitance-type sensor and a gas gage. A curve showing the dependence of internal friction upon a temperature of pure cerium has two distinct peaks; the first at 12.5/sup 0/K, the second at 45/sup 0/K. The 12.5/sup 0/K peak is accounted for by a transition of antiferromagnetic ..beta..-Ce into a paramagnetic state. The 45/sup 0/K peak is a Bordoni maximum. The paper describes an influence of additions, specimen oscillation frequency variations, deformation and annealing upon the peak behavor. Added lanthanum reduces not only a peak temperature but a height as well. Studies of the 45/sup 0/K peak have shown that its temperature location depends upon the specimen oscillation frequency. As the frequency increases the peak tends to a range of high temperatures which confirms its relaxation nature.

  3. Cerium doped hydroxyapatite nanoparticles synthesized by coprecipitation method

    Directory of Open Access Journals (Sweden)

    Ciobanu Carmen Steluta

    2016-01-01

    Full Text Available The present work reports a simple coprecipitation adapted method for the synthesis of stable Ce substituted to Ca hydroxyapatite (HAp nanoparticles. The structural and morphological properties of Ce doped hydroxyapatite (Ce:HAp were characterized by X-ray diffraction (XRD, Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM and Energy Dispersive X-ray analysis (EDAX. The optical properties of Ce doped hydroxyapatite were also investigated using Fourier Transform Infrared (FTIR spectroscopy, FT Raman spectroscopy and photoluminescence analysis. The results of the XRD studies revealed the progressive increase in the a- and c-axes with increasing of Ce concentrations. In the FTIR studies of Ce:HAp powders a similar structure to hydroxyapatite was observed. IR and Raman wavenumbers and the peak strength of the bands associated to the P-O and O-H bonds decreases progressively with the increase of Ce concentration. All the emission maxima could be attributed to the 5d-4f transitions of Ce ions. The displacement of maximum emission bands with the increase of Cerium in the samples is in agreement with the results obtained by XRD studies. The Ce:HAp samples with xCe =0.03 and 0.05 exhibited significant antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli 714 bacterial strains compared to Ce:HAp samples with xCe =0 (pure HAp and 0.01.

  4. Appearance of minimum on the curve of cerium melting

    International Nuclear Information System (INIS)

    Boguslavskij, Yu.Ya.; Grigor'ev, S.B.

    1986-01-01

    It is shown by means of simple and obvious thermodynamical considerations that the reduced stability line continues up to the solid phase boundary. The existence of this line causes the appearance of minimum on the fcc cerium melting curve

  5. A contribution to the radiologic findings in cerium pneumoconiosis

    International Nuclear Information System (INIS)

    Hecht, F.M.; Wesch, H.; Deutsches Krebsforschungszentrum, Heidelberg

    1980-01-01

    Report on a 69 year old man, who had been employed as photographer in the printing industry and who had been exposed to Cerium for 40 years. The chest X-ray which was performed 9 years after the end of the exposure displayes striate densities of the lungs, which must be considered as a late stage of Cerium-pneumoconiosis. The changes which were found fulfill the code 't 1/0 RO, RM, RU, LO, LM, LU, p 0/1 RO, RM, LO, LM, em, tbu' according to the 'ILO U/C 1971 classification of pneumoconiosis'. The diagnosis could be substantiated by measureing Cerium in the lung parenchyma qualitatively and quantitatively using neutrone activating analysis. The radiolgic findings of the Cerium pneumoconiosis are discussed. (orig.) [de

  6. Metabolism of cerium 144 in rat. Distribution - elimination - dosimetry

    International Nuclear Information System (INIS)

    Remy, Jacques

    1959-01-01

    This academic report concerns a study during which cerium 144 has been intravenously injected to three-month old rats under the form of cerium chloride in aqueous solution with pH of 9,5. Rats have then been sacrificed at different times after the injection, and organ or tissue samplings have been performed to study the isotope distribution in their bodies. This allowed the calculation of internal irradiation doses locally received by the animal, and also to identify critical organs with respect to cerium 144. Thus, until the twentieth day after injection, liver is the critical organ. After, it is the skeleton, for the rest of the animal's life. The bone internal irradiation is the highest danger for an internal cerium 144 contamination, due to threats on body hematopoietic functions [fr

  7. Calculation of concentration profiles and their experimental verification with a pulsed sieve-plate column and the reactive material system of uranyl nitrate, nitric acid/tributyl phosphate, kerosine

    International Nuclear Information System (INIS)

    Ihle, E.

    1985-01-01

    The present study is concerned with the calculation of stationary and non-stationary concentration profiles as well as with the starting and disturbance behaviour of a pulsed sieve-plate extraction column. It investigates into the material system HNO 3 /uranyl nitrate in water with 30 per cent by volume of tributyl phosphate in kerosine. During the measurements of the concentration profiles for HNO 3 transition, which were effected in the direction of extraction and reextraction, it was shown that the concentration profiles measured in the mixer-settler range, in spite of a sixfold enlargement of the specific heat transfer area, do not differ essentially from those measured in the dispersion range. During the measurements of concentration profiles for HNO 3 /uranium transition, which were effected in the direction of coextraction and co-reextraction only for mixer-settler range, it was discovered that with increasing phase ratios, there is a depletion of the uranium concentration in the aqueous phase. If the phase ratio is further raised, it is the nitric acid, and not the uranium, that is depleted. (orig./PW) [de

  8. Data on nitrate and nitrate of Taham dam in Zanjan (Iran

    Directory of Open Access Journals (Sweden)

    Mohammadreza Massoudinejad

    2018-04-01

    Full Text Available In recent years, contamination of water resources, with pollutants such as nitrate and nitrite, has significantly increased. These compounds can have harmful effects on human health, especially children such as methemoglobinemia. The main objective of this study was to measure the concentration of nitrate and nitrite and its health-risk assessment in the rivers entering Taham dam in Zanjan. USEPA Method was used to assess the health-risk of nitrate and nitrite. According to the obtained results, the concentration of nitrate and nitrite was in the range of 0.51–14.93 mg/l and 0.001–0.061 mg/l, respectively. According to the results, the mean of the CDI for nitrate and nitrite was 9.52*10−2 and 3.63*10−4 mg/kg/day, respectively. Furthermore, the mean HI for nitrate and nitrite was 5.97*10−2 and 3.63*10−3, respectively. The concentration of nitrate and nitrite in rivers was lower than the WHO and Iran guidelines. Based on the results, the HI value in all samples was less than 1 which indicating the non-carcinogenic effects of nitrate and nitrite in these rivers. Keywords: Nitrate, Nitrite, Water quality, Dam

  9. Comparative evaluation of nitrate removal technologies

    International Nuclear Information System (INIS)

    Darbi, A.; Viraraghavan, T.; Butler, R.; Corkal, D.

    2002-01-01

    Due to the extensive application of artificial nitrogen-based fertilizers and animal manure on land, many water agencies face problems of increasing concentrations of nitrate in groundwater. The contamination of groundwater by nitrate may pose a significant public health problem. The threat of methemoglobinemia is well documented and reflected in the U.S. drinking water standard of 10 mg/L as nitrate-nitrogen. Approximately 45% of Saskatchewan's population use groundwater for drinking purposes, out of which, approximately 23% (230,000) are rural residents. The water used is made available from over 48,000 privately owned wells in regions where there is an extensive application of chemical fertilizers. Biological denitrification, ion exchange and reveres osmosis (RO) processes were selected for further study. Field studies were conducted on these processes. The sulfur/limestone autotrophic denitrification (SLAD) process was selected to achieve biological removal of nitrate from groundwater. The feasibility of the system was evaluated under anaerobic conditions. An ion exchange study was conducted using Ionac A554 which is strong anion exchange resins. In the case of groundwater containing low sulfate concentrations, A554 offered high nitrate removal. However, the disposal of regenerant brine can be a problem. A reverse osmosis unit with Filmtec membrane elements (FT30-Element Family) was used in the study on nitrate removal. The unit effluent average nitrate concentration was less than the maximum allowable concentration. (author)

  10. Modeled Wet Nitrate Deposition

    Data.gov (United States)

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  11. Thin film ionic conductors based on cerium oxide

    International Nuclear Information System (INIS)

    Haridoss, P.; Hellstrom, E.; Garzon, F.H.; Brown, D.R.; Hawley, M.

    1994-01-01

    Fluorite and perovskite structure cerium oxide based ceramics are a class of materials that may exhibit good oxygen ion and/or protonic conductivity. The authors have successfully deposited thin films of these materials on a variety of substrates. Interesting orientation relationships were noticed between cerium oxide films and strontium titanate bi-crystal substrates. Near lattice site coincidence theory has been used to study these relationships

  12. Further results on cerium fluoride crystals

    International Nuclear Information System (INIS)

    Anderson, S.; Auffray, E.; Aziz, T.; Baccaro, S.; Banerjee, S.; Bareyre, P.; Barone, L.E.; Borgia, B.; Boutet, D.; Burq, J.P.; Chemarin, M.; Chipaux, R.; Dafinei, I.; D'Atanasio, P.; De Notaristefani, F.; Dezillie, B.; Dujardin, C.; Dutta, S.; Faure, J.L.; Fay, J.; Ferrere, D.; Francescangeli, O.; Fuchs, B.A.; Ganguli, S.N.; Gillespie, G.; Goyot, M.; Gupta, S.K.; Gurtu, A.; Heck, J.; Herve, A.; Hillemanns, H.; Holdener, F.; Ille, B.; Joensson, L.; Kierstead, J.; Krenz, W.; Kway, W.; Le Goff, J.M.; Lebeau, M.; Lebrun, P.; Lecoq, P.; Lemoigne, Y.; Loomis, G.; Lubelsmeyer, K.; Madjar, N.; Majni, G.; El Mamouni, H.; Mangla, S.; Mares, J.A.; Martin, J.P.; Mattioli, M.; Mauger, G.J.; Mazumdar, K.; Mengucci, P.; Merlo, J.P.; Moine, B.; Nikl, N.; Pansart, J.P.; Pedrini, C.; Poinsignon, J.; Polak, K.; Raghavan, R.; Rebourgeard, P.; Rinaldi, D.; Rosa, J.; Rosowsky, A.; Sahuc, P.; Samsonov, V.; Sarkar, S.; Schegelski, V.; Schmitz, D.; Schneegans, M.; Seliverstov, D.; Stoll, S.; Sudhakar, K.; Svensson, A.; Tonwar, S.C.; Topa, V.; Vialle, J.P.; Vivargent, M.; Wallraff, W.; Weber, M.J.; Winter, N.; Woody, C.; Wuest, C.R.; Yanovski, V.

    1993-01-01

    A systematic investigation of the properties of cerium fluoride monocrystals has been performed by the 'Crystal Clear' collaboration in view of a possible use of such crystals for the construction of high precision electromagnetic calorimeters for the future generation of high luminosity accelerators. A large sample of different crystals grown by several producers has been studied. The spectroscopic characteristics, the transmission, luminescence and excitation spectra and the decay time curves are analysed. The light yield of the different crystals is measured with photomultipliers and Si photodiodes and compared to reference standards like BGO and NaI(Tl). The radiation damage behaviour is then presented for γ and neutron irradiations, at different doses and dose rates, including thermal and optical bleaching. (orig.)

  13. Cerium intermetallics CeTX. Review III

    Energy Technology Data Exchange (ETDEWEB)

    Poettgen, Rainer; Janka, Oliver [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Chevalier, Bernard [Bordeaux Univ., Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux

    2016-05-01

    The structure-property relationships of CeTX intermetallics with structures other than the ZrNiAl and TiNiSi type are systematically reviewed. These CeTX phases form with electron-poor and electron-rich transition metals (T) and X = Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi. The review focusses on the crystal chemistry, the chemical bonding peculiarities, and the magnetic and transport properties. Furthermore {sup 119}Sn Moessbauer spectroscopic data, high-pressure studies, hydrogenation reactions and the formation of solid solutions are reviewed. This paper is the third of a series of four reviews on equiatomic intermetallic cerium compound [Part I: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 289; Part II: R. Poettgen, B. Chevalier, Z. Naturforsch. 2015, 70b, 695].

  14. Characterization of composite metal-ceramic of nickel-oxide cerium doped gadolinium; Caracterizacao de compositos ceramica-metal de niquel e oxido de cerio dopado com gadolinio

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.L.A. da, E-mail: maria.andrade@pro.unifacs.br [Universidade Salvador (UNIFACS), BA (Brazil). Escola de Engenharia, Arquitetura e TI; Universidade Federal da Bahia (UFBA), BA (Brazil); Varela, M.C.R.S. [Universidade Federal da Bahia (UFBA), BA (Brazil)

    2016-07-01

    Composite nickel doped cerium oxide are used in SOFC anode materials. In this study we evaluated the effect of the presence of gadolinium on the properties of composite nickel and ceria and. The supports were synthesized by sol-gel method. The impregnation with nickel nitrate was taken sequentially, followed by calcination. The materials were characterized by X-ray diffraction, measurement of specific surface area, temperature programmed reduction, Raman spectroscopy. The presence of gadolinium retained the fluorite structure of ceria by forming a solid solution, also not influencing significantly on the specific surface area of the support. On the other hand, there was a decrease in the area catalysts, which can be attributed to sintering of nickel. Furthermore, addition of gadolinium favored the formation of intrinsic and extrinsic vacancies in cerium oxide, which leads to an increase in the ionic conductivity of the solid, desirable property for an SOFC anode catalyst. (author)

  15. Comparison of Titration ICP and XRF Spectrometry Methods in Determination of Cerium in Lens Polishing Powder

    International Nuclear Information System (INIS)

    Ninlaphruk, Sumalee; Pichestapong, Pipat; Mungpayabal, Harinate; Jiyavaranant, Thitima; Srisukho, Supapan; Chaisai, Prapassurn

    2004-10-01

    Three analytical methods in determination of cerium in cerium oxide separated from monazite ore for producing lens polishing powder were compared. These methods are titration ICP and XRF spectrometry techniques. The cerium oxide sample with estimated 45% cerium content needed to be digested and converted into solution before the analysis. The analytical results shown significantly no difference between each method. However, the titration method was found to be more convenient and suitable for quality control in the production of cerium oxide as it does not require standard cerium and the complicated analytical instruments

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

    OpenAIRE

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

    2013-01-01

    Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the ‘store’ of nitrate and its potentially long travel time in the unsaturated and satura...

  17. Nitrate removal by electro-bioremediation technology in Korean soil

    International Nuclear Information System (INIS)

    Choi, Jeong-Hee; Maruthamuthu, Sundaram; Lee, Hyun-Goo; Ha, Tae-Hyun; Bae, Jeong-Hyo

    2009-01-01

    The nitrate concentration of surface has become a serious concern in agricultural industry through out the world. In the present study, nitrate was removed in the soil by employing electro-bioremediation, a hybrid technology of bioremediation and electrokinetics. The abundance of Bacillus spp. as nitrate reducing bacteria were isolated and identified from the soil sample collected from a greenhouse at Jinju City of Gyengsangnamdo, South Korea. The nitrate reducing bacterial species were identified by 16 s RNA sequencing technique. The efficiency of bacterial isolates on nitrate removal in broth was tested. The experiment was conducted in an electrokinetic (EK) cell by applying 20 V across the electrodes. The nitrate reducing bacteria (Bacillus spp.) were inoculated in the soil for nitrate removal process by the addition of necessary nutrient. The influence of nitrate reducers on electrokinetic process was also studied. The concentration of nitrate at anodic area of soil was higher when compared to cathode in electrokinetic system, while adding bacteria in EK (EK + bio) system, the nitrate concentration was almost nil in all the area of soil. The bacteria supplies electron from organic degradation (humic substances) and enhances NO 3 - reduction (denitrification). Experimental results showed that the electro-bio kinetic process viz. electroosmosis and physiological activity of bacteria reduced nitrate in soil environment effectively. Involvement of Bacillus spp. on nitrification was controlled by electrokinetics at cathode area by reduction of ammonium ions to nitrogen gas. The excellence of the combined electro-bio kinetics technology on nitrate removal is discussed.

  18. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued by the U.S. Department of Agriculture for use as sources of...

  19. Electrochemical reduction of cerium oxides in molten salts

    International Nuclear Information System (INIS)

    Claux, B.; Serp, J.; Fouletier, J.

    2011-01-01

    This brief article describes a pyrochemical process that is used by CEA to turn actinide oxides into metal actinides. This process is applied to Cerium oxides (CeO 2 ) that simulate actinide oxides well chemically as cerium belongs to the lanthanide family. The process is in fact an electrolysis of cerium oxide in a bath of molten calcium chloride salt whose temperature is between 800 and 900 Celsius degrees. At those temperatures calcium chloride becomes a ionic liquid (Ca 2+ and Cl - ) that is a good electrical conductor and is particularly well-adapted as solvent to an electrolytic process. The electrolysis current allows the transformation of solvent Ca 2+ ions into metal calcium which, in turn, can reduce cerium oxide into metal cerium through chromatically. Experimental data shows the reduction of up to 90% of 10 g samples of CeO 2 in a 6 hour long electrolysis while the best reduction rate ever known was 80% so far. This result is all the more promising that cerium oxides are more difficult to reduce than actinide oxides from the thermodynamical perspective

  20. The influence of operational parameters on the performance of an undivided zinc–cerium flow battery

    International Nuclear Information System (INIS)

    Leung, P.K.; Ponce de Leon, C.; Walsh, F.C.

    2012-01-01

    Highlights: ► The performance of an undivided zinc–cerium flow battery under different conditions of temperature, concentration and electrolyte flow rate, was evaluated. ► Mixed electrolytes were considered; methanesulfonate and sulfate anions were tested. ► In a 30 min charge/discharge at 20 mA cm −2 , charge and energy efficiencies were 82% and 72%, respectively. ► After 4 h charge, the conversion of Ce(III) to Ce(IV) became less efficient with the oxygen evolution reaction becoming more favored. ► After a larger number of cycles the carbon felt electrode was electro- and chemically-oxidized by Ce(IV) leading to degradation of the positive electrode. - Abstract: An undivided zinc–cerium redox flow battery was studied under a wide range of operational conditions, including: (i) electrolyte composition; the concentrations of ([Zn 2+ ], [Ce 3+ ] and [H + ]), (ii) current density (0–80 mA cm −2 ), (iii) electrolyte flow linear velocity (0.64–7.0 cm s −1 ) and (iv) temperature (20–60 °C). The charge efficiency increased at higher current densities and at higher electrolyte flow velocities. Unlike the divided zinc–cerium system, the charge–discharge performance decreased at higher temperature, since oxygen evolution became increasingly favored at the positive electrode. The use of a low acid concentration led to a poor conversion of Ce(III) to Ce(IV) ions during the discharge cycle. Mixed electrolytes containing methanesulfonate and sulfate anions have been evaluated at a high Ce(III) ion concentration, e.g. 0.4 mol dm −3 . After charging the battery for 4 h, the conversion of Ce(III) to Ce(IV) ions became less efficient over time due to a greater fraction of the current being used in oxygen evolution. Critical aspects for improvements in the battery performance are considered.

  1. Metabolism of cerium 144 in rat. Distribution - elimination - dosimetry; Metabolisme du cerium 144 chez le rat. Distribution - elimination - dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Remy, Jacques

    1959-07-01

    This academic report concerns a study during which cerium 144 has been intravenously injected to three-month old rats under the form of cerium chloride in aqueous solution with pH of 9,5. Rats have then been sacrificed at different times after the injection, and organ or tissue samplings have been performed to study the isotope distribution in their bodies. This allowed the calculation of internal irradiation doses locally received by the animal, and also to identify critical organs with respect to cerium 144. Thus, until the twentieth day after injection, liver is the critical organ. After, it is the skeleton, for the rest of the animal's life. The bone internal irradiation is the highest danger for an internal cerium 144 contamination, due to threats on body hematopoietic functions [French] Le Cerium 144 est injecte a des rats de trois mois par voie intraveineuse, sous forme de chlorure en solution aqueuse a pH = 9,5. Une telle solution est colloidale. Les rats sont sacrifies par groupe de 5 a des temps differents apres l'injection et des prelevements d'organes ou de tissus sont effectues qui permettent d'etudier la distribution de l'isotope dans l'organisme. Cette etude de la distribution du Cerium 144 dans l'organiqme du rat a permis egalement le calcul des doses d'irradiation interne recues localement par l'animal. Ces donnees permettent de definir les organes critiques de l'organisme pour le Cerium 144: Jusqu'au 20eme jour l'organe critique est le foie. Ce sera ensuite le squelette, et ce, pendant toute la vie de l'animal. L'irradiation interne de l'os constitue, en raison des menaces qu'elle comporte pour les fonctions hematopoietiques de l'organisme, le plus grand danger d'une contamination interne par le Cerium 144.

  2. Effect of concentrations of plasticizers on the sol-gel properties developed from alkoxides precursors

    Energy Technology Data Exchange (ETDEWEB)

    Kunst, Sandra Raquel; Longhi, Marielen; Zini, Lucas Pandolphi [Universidade de Caxias do Sul (CCET/UCS), Caxias do Sul, RS (Brazil). Centro de Ciências Exatas e Tecnologia; Beltrami, Lilian Vanessa Rossa; Boniatti, Rosiana; Cardoso, Henrique Ribeiro Piaggio; Vega, Maria Rita Ortega; Malfatti, Célia de Fraga, E-mail: lvrossa@yahoo.com.br [Universidade Federal do Rio Grande do Sul (LAPEC/UFRGS), Porto Alegre, RS (Brazil). Laboratorio de Pesquisa em Corrosão

    2017-07-01

    Coatings developed through sol-gel method is presented as an interesting replacement to chromium coating. Sol-gel method present advantages as high purity and excellent distribution of the components. The objective of this work is to synthesize and characterize a film obtained by sol-gel route. The film was prepared with 3-(trimethoxysilylpropyl) methacrylate (TMSPMA), tetraethoxysilane (TEOS) and cerium nitrate, using water and ethanol as solvents. Polyethyleneglycol (PEG) plasticizer was added at four different concentrations. The sol was characterized by techniques of viscosity, thermogravimetric analysis (TGA), X-ray diffraction (XRD) nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FT-IR). The results showed that tetrafunctional alkoxides condensation was retarded by the plasticizer, forming a compact film. The film with 20 g.L-1 of PEG showed the best electrochemical behavior. (author)

  3. Effect of concentrations of plasticizers on the sol-gel properties developed from alkoxides precursors

    Directory of Open Access Journals (Sweden)

    Sandra Raquel Kunst

    Full Text Available Abstract Coatings developed through sol-gel method is presented as an interesting replacement to chromium coating. Sol-gel method present advantages as high purity and excellent distribution of the components. The objective of this work is to synthesize and characterize a film obtained by sol-gel route. The film was prepared with 3-(trimethoxysilylpropyl methacrylate (TMSPMA, tetraethoxysilane (TEOS and cerium nitrate, using water and ethanol as solvents. Polyethyleneglycol (PEG plasticizer was added at four different concentrations. The sol was characterized by techniques of viscosity, thermogravimetric analysis (TGA, X-ray diffraction (XRD nuclear magnetic resonance spectroscopy (NMR and Fourier transform infrared spectroscopy (FT-IR. The results showed that tetrafunctional alkoxides condensation was retarded by the plasticizer, forming a compact film. The film with 20 g.L-1 of PEG showed the best electrochemical behavior.

  4. Changes in EC , pH and in the concentrations of nitrate, ammonium, sodium and chlorine in the drainage solution of a crop of roses on substrates with drainage recycling

    Directory of Open Access Journals (Sweden)

    Mariela Rodríguez

    2012-08-01

    Full Text Available The rose cultivation system has been changing from soil to substrate on the Plateau of Bogota. The objective of this study was the monitoring of the EC, pH, and the levels of nitrate, ammonium, sodium and chlorine in a drainage solution in a crop of roses with substrates based on burnt rice husk and coconut fiber. The Charlotte rose variety grafted onto ‘Natal Briar’ was planted in a greenhouse located in one of the SENA facilities in Mosquera (Colombia; with a density of 6.5 plants/ m². For this experiment, a split plot design was used arranged in randomized blocks with a three-level recirculating system (0, 50 and 100% on the substrates 100% burnt rice husk; 65% burnt rice husk plus 35% coconut fiber; and 35% burnt rice husk plus 65% coconut fiber, repeated three times. The EC decreased from 2.7 to 1.3 mS cm-1 within weeks 2 and 5 which demonstrated an increase of mineral consumption by the plants. The pH levels dropped from 7.46 to 6.27 within weeks 3 to 8 and then increased to 7.39 within weeks 8 to 12. Nitrate concentrations showed a decreasing trend in recirculation treatments within weeks 2 to 12. A lower ammonium concentration was observed at week 4 in treatments with and without recirculation during the vegetative stage. The levels of sodium and chloride increased in treatments with a recirculation system, without signs of toxicity

  5. Is nitrate an endocrine active compound in fish?

    DEFF Research Database (Denmark)

    Mose, M. P.; Kinnberg, Karin Lund; Bjerregaard, Poul

    Nitrate and nitrite taken up into fish may be reduced to NO which is known to be a signalling compound in the organism contributing to the regulation of i.e. steroid synthesis. Exposure of male rats to nitrate and nitrite results in reduced plasma concentrations of testosterone (also nitrate...... concentrations around or below the limits for drinking water). Nitrate concentrations in streams may be elevated due to releases from agricultural practices. The effects of nitrate and nitrite on endocrine relevant endpoints were investigated in zebrafish (Danio rerio) and brown trout (Salmo trutta). Zebrafish...... were exposed to nitrate and nitrite from hatch to sexual maturation (60 d) and sex ratio and vitellogenin concentrations were determined. Juvenile brown trout were exposed in a short-term experiment and the concentrations of vitellogenin were determined. The sex ratio in zebrafish was not affected...

  6. CARBON-BASED REACTIVE BARRIER FOR NITRATE ...

    Science.gov (United States)

    Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constructed for in-situ bioremediation of a ground water nitrate plume caused by leakage from a swine CAFO (concentrated animal feeding operation) lagoon. The swine CAFO, located in Logan County, Oklahoma, was in operation from 1992-1999. The overall site remediation strategy includes an ammonia recovery trench to intercept ammonia-contaminated ground water and a hay straw PRB which is used to intercept a nitrate plume caused by nitrification of sorbed ammonia. The PRB extends approximately 260 m to intercept the nitrate plume. The depth of the trench averages 6 m and corresponds to the thickness of the surficial saturated zone; the width of the trench is 1.2 m. Detailed quarterly monitoring of the PRB began in March, 2004, about 1 year after construction activities ended. Nitrate concentrations hydraulically upgradient of the PRB have ranged from 23 to 77 mg/L N, from 0 to 3.2 mg/L N in the PRB, and from 0 to 65 mg/L N hydraulically downgradient of the PRB. Nitrate concentrations have generally decreased in downgradient locations with successive monitoring events. Mass balance considerations indicate that nitrate attenuation is dominantly from denitrification but with some component of

  7. Impact of Sulfide on Nitrate Conversion in Eutrophic Nitrate-Rich Marine Sludge

    DEFF Research Database (Denmark)

    Schwermer, Carsten U.; Krieger, Bärbel; Lavik, Gaute

    2006-01-01

    IMPACT OF SULFIDE ON NITRATE CONVERSION IN EUTROPHIC NITRATE-RICH MARINE SLUDGE C.U. Schwermer 1, B.U. Krieger 2, G. Lavik 1, A. Schramm 3, J. van Rijn 4, D. de Beer 1, D. Minz 5, E. Cytryn 4, M. Kuypers 1, A. Gieseke 1 1 Max Planck Institute for Marine Microbiology, Bremen, Germany; 2 Dept...... nitrate conversion from denitrification to dissimilatory nitrate-reduction to ammonium (DNRA). In situ microsensor profiling in stagnant sludge revealed the typical stratification of nitrate reduction on top of sulfate reduction. Increasing the bulk nitrate concentration lead to a downward shift....... Our results show that the presence of sulfide generally decreased growth rates but increased N2O production. We conclude that sulfide plays a key role in causing incomplete denitrification, presumably by inhibiting the N2O reductase, and enhancing DNRA compared to denitrification.  ...

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

    Science.gov (United States)

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

    2013-10-01

    Nitrate pollution in groundwater, which is mainly from agricultural activities, remains an international problem. It threatens the environment, economics and human health. There is a rising trend in nitrate concentrations in many UK groundwater bodies. Research has shown it can take decades for leached nitrate from the soil to discharge into groundwater and surface water due to the 'store' of nitrate and its potentially long travel time in the unsaturated and saturated zones. However, this time lag is rarely considered in current water nitrate management and policy development. The aim of this study was to develop a catchment-scale integrated numerical method to investigate the nitrate lag time in the groundwater system, and the Eden Valley, UK, was selected as a case study area. The method involves three models, namely the nitrate time bomb-a process-based model to simulate the nitrate transport in the unsaturated zone (USZ), GISGroundwater--a GISGroundwater flow model, and N-FM--a model to simulate the nitrate transport in the saturated zone. This study answers the scientific questions of when the nitrate currently in the groundwater was loaded into the unsaturated zones and eventually reached the water table; is the rising groundwater nitrate concentration in the study area caused by historic nitrate load; what caused the uneven distribution of groundwater nitrate concentration in the study area; and whether the historic peak nitrate loading has reached the water table in the area. The groundwater nitrate in the area was mainly from the 1980s to 2000s, whilst the groundwater nitrate in most of the source protection zones leached into the system during 1940s-1970s; the large and spatially variable thickness of the USZ is one of the major reasons for unevenly distributed groundwater nitrate concentrations in the study area; the peak nitrate loading around 1983 has affected most of the study area. For areas around the Bowscar, Beacon Edge, Low Plains, Nord Vue

  9. Nitrate reduction in an unconfined sandy aquifer

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Boesen, Carsten; Kristiansen, Henning

    1991-01-01

    of total dissolved ions in the NO3- free anoxic zone indicates the downward migration of contaminants and that active nitrate reduction is taking place. Nitrate is apparently reduced to N2 because both nitrite and ammonia are absent or found at very low concentrations. Possible electron donors......Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate...... processes of O2 and NO3- occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content...

  10. Do nitrates differ?

    Science.gov (United States)

    Fung, H.-L.

    1992-01-01

    1 The organic nitrates all share a common biochemical and physiological mechanism of action. 2 The organic nitrates differ substantially in their pharmacologic potency and pharmacokinetics. In vitro potency differences appear larger than the corresponding in vivo activities. 3 The duration of action of organic nitrates, after a single immediate-release dose, is governed by the pharmacokinetics of the drug. However, the duration of action of available sustained-release preparations, whatever the nitrate or formulation, is limited to about 12 h, due to the development of pharmacologic tolerance. 4 Nitrates do not appear to differ in their production of undesirable effects. PMID:1633079

  11. Study on removing nitrate from uranium solution by ion-exchange method

    International Nuclear Information System (INIS)

    Zhou Genmao

    2004-01-01

    Nitrate of low concentration can interfere with adsorption of uranyl sulfate anion on anion-exchange resins because the anion-exchange resins have a stronger affinity for nitrate in uranium solution. Nitrate can be adsorbed with a high efficiency resin, then desorbed by sodium hydroxide. The nitrate concentration is about 60 g/L in eluate. The research results show that nitrate can be recovered from uranium solution with N-3 anion-exchange resin

  12. Ammonium nitrate explosion hazards

    Directory of Open Access Journals (Sweden)

    Negovanović Milanka

    2015-01-01

    Full Text Available Ammonium nitrate (AN primarily is used as a fertilizer but it is also very important compound in the production of industrial explosives. The application of ammonium nitrate in the production of industrial explosives was related with the early era of Nobel dynamite and widely increased with the appearance of blasting agents such as ANFO and Slurry, in the middle of the last Century. Throughout the world millions of tons of ammonium nitrate are produced annually and handled without incident. Although ammonium nitrate generally is used safely, accidental explosions involving AN have high impact resulting in loss of lives and destruction of property. The paper presents the basic properties of ammonium nitrate as well as hazards in handling of ammonium nitrate in order to prevent accidents. Several accidents with explosions of ammonium nitrate resulted in catastrophic consequences are listed in the paper as examples of non-compliance with prescribed procedures.

  13. Cerium oxide nanoparticles stimulate proliferation of primary mouse embryonic fibroblasts in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Popov, Anton L., E-mail: antonpopovleonid@gmail.com [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow region (Russian Federation); Popova, Nelly R. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow region (Russian Federation); Selezneva, Irina I. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow region (Russian Federation); Pushchino State Institute of Natural sciences, Pushchino, Moscow region (Russian Federation); Akkizov, Azamat Y. [Kabardino-Balkarian State University, Nalchik (Russian Federation); Ivanov, Vladimir K. [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); National Research Tomsk State University, Tomsk (Russian Federation)

    2016-11-01

    The increasing application of cell therapy technologies in the treatment of various diseases requires the development of new effective methods for culturing primary cells. The major limitation for the efficient use of autologous cell material is the low rate of cell proliferation. Successful cell therapy requires sufficient amounts of cell material over a short period of time with the preservation of their differentiation and proliferative potential. In this regard, the development of novel, highly efficient stimulators of proliferative activity in stem cells is a truly urgent task. In this paper we have demonstrated that citrate-stabilized cerium oxide nanoparticles (nanoceria) enhance the proliferative activity of primary mouse embryonic fibroblasts in vitro. Cerium oxide nanoparticles stimulate cell proliferation in a wide range of concentrations (10{sup −3} M–10{sup −9} M) through reduction of intracellular levels of reactive oxygen species (ROS) during the lag phase of cell growth and by modulating the expression level of the major antioxidant enzymes. We found the optimal concentration of nanoceria, which provides the greatest acceleration of cell proliferation in vitro, while maintaining the levels of intracellular ROS and mRNA of antioxidant enzymes in the physiological range. Our results confirm that nanocrystalline ceria can be considered as a basis for effective and inexpensive supplements in cell culturing. - Highlights: • Citrate-stabilized cerium oxide nanoparticles are shown to stimulate proliferation of primary embryonic cells in vitro. • Some of mechanisms involved in stimulating of the proliferation by CeO{sub 2} have been uncovered. • The most effective (optimal) concentration of CeO{sub 2} nanoparticles for stimulation of proliferation was determined.

  14. Corrosion behaviour of nanometre sized cerium oxide and titanium oxide incorporated aluminium in NaCl solution

    International Nuclear Information System (INIS)

    Ashraf, P. Muhamed; Edwin, Leela

    2013-01-01

    Highlights: ► Corrosion resistant aluminium incorporated with nano oxides of cerium and titanium. ► 0.2% nano CeO 2 and 0.05% nano TiO 2 showed increased corrosion resistance. ► Nano TiO 2 concentration influenced the optimum performance of the material. ► Comparison of Micro and nano CeO 2 and TiO 2 aluminium showed the latter is best. - Abstract: The study highlights the development of an aluminium matrix composite by incorporating mixture of nanometre sized cerium oxide and titanium oxide in pure aluminium and its corrosion resistance in marine environment. The mixed nanometre sized oxides incorporated aluminium exhibited improved microstructure and excellent corrosion resistance. Corrosion resistance depends on the concentration of nanometre sized titanium oxide. Electrochemical characteristics improved several folds in nanometre sized mixed oxides incorporated aluminium than micrometre sized oxides incorporated aluminium.

  15. Correlation between total nitrite/nitrate concentrations and monoamine oxidase (types A and B) and semicarbazide-sensitive amine oxidase enzymatic activities in human mesenteric arteries from non-diabetic and type 2 diabetic patients

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, S.F.; Figueiredo, I.V. [Laboratório de Farmacologia, Faculdade de Farmácia, Universidade de Coimbra, Coimbra (Portugal); Pereira, J.S. [Instituto Português de Oncologia de Coimbra, Coimbra (Portugal); Lopes, M.C.; Caramona, M.M. [Laboratório de Farmacologia, Faculdade de Farmácia, Universidade de Coimbra, Coimbra (Portugal)

    2011-11-25

    The aim of this study was to determine the correlation between total nitrite/nitrate concentrations (NOx) and the kinetic parameters of monoamine oxidase enzymes (MAO-A and MAO-B) and semicarbazide-sensitive amine oxidase (SSAO) in human mesenteric arteries. Arteries were from non-diabetic and type 2 diabetic patients with sigmoid or rectum carcinoma for whom surgery was the first option and who were not exposed to neo-adjuvant therapy. Segments of human inferior mesenteric arteries from non-diabetic (61.1 ± 8.9 years old, 7 males and 5 females, N = 12) and type 2 diabetic patients (65.8 ± 6.2 years old, 8 males and 4 females, N = 12) were used to determine NOx concentrations and the kinetic parameters of MAO-A, MAO-B and SSAO by the Griess reaction and by radiochemical assay, respectively. The NOx concentrations in arteries from diabetic patients did not differ significantly from those of the non-diabetic group (10.28 ± 4.61 vs 10.71 ± 4.32 nmol/mg protein, respectively). In the non-diabetic group, there was a positive correlation between NOx concentrations and MAO-B parameters: K{sub m} (r = 0.612, P = 0.034) and V{sub max} (r = 0.593, P = 0.042), and a negative correlation with the SSAO parameters: K{sub m} (r = -0.625, P = 0.029) and V{sub max} (r = -0.754, P = 0.005). However, in the diabetic group no correlation was found between NOx concentrations and the three kinetic parameters of the enzymes. These results suggest an important function of sympathetic nerves and vascular NOx concentrations in arteries of non-diabetic patients. Thus, these results confirm the importance of a balance between oxidants and antioxidants in the maintenance of vascular homeostasis to prevent oxidative stress.

  16. Kinetics of bromide catalysed oxidation of dextrose by cerium (IV) in aqueous sulphuric acid solution

    International Nuclear Information System (INIS)

    Sharma, J.; Sah, M.P.

    1994-01-01

    Kinetics of bromide catalysed oxidation of dextrose by Ce IV in aqueous sulphuric acid medium show first order dependence each in dextrose and cerium(IV). The reaction rate decreases on increasing the concentration of hydrogen ion. The increase in [HSO 4 - ] or [SO 4 2- ] decreases the rate. The bromide ion shows positive catalytic effect on the reaction rate. The value of activation energy has been calculated and a suitable mechanism confirming to the kinetic data is proposed. (author). 3 refs., 3 tabs

  17. Trace electrochemical analysis of Europium, Ytterbium, and Cerium at their joint presence in solution

    Directory of Open Access Journals (Sweden)

    Rema Matakova

    2012-03-01

    Full Text Available In the course of several decades at the department of analytical chemistry and chemistry of rare elements there were studied the electrode processes with participation of rare-earth metals (REM in accordance with the long awaiting problem of the development of rare-metal and rare-earth branch of non-ferrous metallurgy of Kazakhstan. With the aim of express and highly sensitive analytical control of raw materials and final product of rare-earth industry there were developed the methods of inversion-voltamperometric determination of low concentrations of europium, ytterbium and cerium under the conditions of their individual and combined presence in the solution.

  18. Kinetics and mechanism of reduction of cerium(IV) by ascorbic acid

    International Nuclear Information System (INIS)

    Bhatt, K.; Nand, K.C.

    1979-01-01

    The reduction of cerium(IV) has been studied in sulfuric acid medium using ascorbic acid as the reductant. The rate is found to be function of both Ce(IV) and AH 2 concentrations. Sulfuric acid retards the rate and the inverse order with respect to sulfuric acid is unity. The addition of chloride, bisulfate and sulfate of sodium show negative salt effect and an increase in the dielectric constant of the medium shows an accelerating effect on the reaction rate. Arrhenius parameters have been evaluated. A mechanism involving intermediate formation of ascorbate radical (AH) is proposed and the derived rate law agrees well with the experimental observations. (author)

  19. Analysis of the effects of cerium on calcium ion in the protoplasts of ...

    African Journals Online (AJOL)

    Administrator

    2011-09-12

    Sep 12, 2011 ... African Journal of Biotechnology Vol. 10(52), pp. ... Paper. Analysis of the effects of cerium on calcium ion in the .... plasma membrane (Zeng et al., 2003). Recently .... cerium on vegetable growth of wheat (Triticum aestivum L.).

  20. Separation of cerium and fractionation of rare earths from mixed chlorides

    International Nuclear Information System (INIS)

    Silva Queiroz, C.A. da; Sood, S.P.; Abrao, A.

    1982-01-01

    The separation of cerium from rare earths chlorides solutions by precipitation with hydrogen peroxide/air/dil. ammonium hydroxide; purification of cerium; fractionation by ion exchange and analytical control of the process are presented. (A.R.H.) [pt

  1. Molecular and physiological responses to titanium dioxide and cerium oxide nanoparticles in Arabidopsis

    Science.gov (United States)

    - Changes in tissue transcriptomes and productivity of Arabidopsis thaliana were investigated during exposure of plants to two widely-used engineered metal oxide nanoparticles, titanium dioxide (nano-titanium) and cerium dioxide (nano-cerium). Microarray analyses confirmed that e...

  2. Influence of the nitrate concentration and source in the incorporation of 14CO2 by the RuBP-carboxylase from wheat (triticum aestivum) and maize (zea mays)

    International Nuclear Information System (INIS)

    Saez Angulo, R.M.; Gines Diaz, M.J.; Garcia Pineda, M.D.

    1982-01-01

    The effect of the concentration and source of nitrogen in the culture media has been studied regarding its influence in the activity of the RuBP-carboxylase from wheat and maize during the first month of development. Wheat and maize has been chosen as plants representatives of two different types of CO 2 assimilation: C3 and M- respectively. Plants have been grown in hydroponic media and under temperature, humidity and nutrient salts control. A negative effect of NH 4 has been observed in the enzymatic activity of wheat seedlings, being this effect more remarkable as NH 4 concentration increases and as long the time of treatment. In our experimental conditions the most favorable source of nitrogen has been N0 3 NH 4 . The specific activity of the enzyme from wheat is about four times higher than in maize, even it decreases with time. This decreasing has not been observed in maize, with the exception of total absence of nitrogen in the media. We have not seen significant differences between the two photo periods which have been tested. Also, no differences have been found in the enzyme activities at the different NO 3 NH 4 concentrations assayed, and it seems that RuBP-carboxylase metabolism is only affected in the case of absolute stress. (Author) 20 refs

  3. Influence of agglomeration of cerium oxide nanoparticles and speciation of cerium(III) on short term effects to the green algae Chlamydomonas reinhardtii

    Energy Technology Data Exchange (ETDEWEB)

    Röhder, Lena A. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Brandt, Tanja [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); Sigg, Laura [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland); ETH-Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Zürich 8092 (Switzerland); Behra, Renata, E-mail: Renata.behra@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, Dübendorf 8600 (Switzerland)

    2014-07-01

    Highlights: • Phosphate-dispersed CeO₂ NP did not affect photosynthetic yield in C. reinhardtii. • Agglomerated CeO₂ NP slightly decreased photosynthetic yield. • Cerium(III) was shown to affect photosynthetic yield and intracellular ROS level. • Slight effects of CeO₂ NP were caused by dissolved Ce³⁺ ions present in suspensions. • Wild type and cell wall free mutant of C. reinhardtii showed the same sensitivity. - Abstract: Cerium oxide nanoparticles (CeO₂ NP) are increasingly used in industrial applications and may be released to the aquatic environment. The fate of CeO₂ NP and effects on algae are largely unknown. In this study, the short term effects of CeO₂ NP in two different agglomeration states on the green algae Chlamydomonas reinhardtii were examined. The role of dissolved cerium(III) on toxicity, its speciation and the dissolution of CeO₂ NP were considered. The role of cell wall of C. reinhardtii as a barrier and its influence on the sensitivity to CeO₂ NP and cerium(III) was evaluated by testing both, the wild type and the cell wall free mutant of C. reinhardtii. Characterization showed that CeO₂ NP had a surface charge of ~0 mV at physiological pH and agglomerated in exposure media. Phosphate stabilized CeO₂ NP at pH 7.5 over 24 h. This effect was exploited to test CeO₂ NP dispersed in phosphate with a mean size of 140 nm and agglomerated in absence of phosphate with a mean size of 2000 nm. The level of dissolved cerium(III) in CeO₂ NP suspensions was very low and between 0.1 and 27 nM in all tested media. Exposure of C. reinhardtii to Ce(NO₃)₃ decreased the photosynthetic yield in a concentration dependent manner with EC₅₀ of 7.5 ± 0.84 μM for wild type and EC₅₀ of 6.3 ± 0.53 μM for the cell wall free mutant. The intracellular level of reactive oxygen species (ROS) increased upon exposure to Ce(NO₃)₃ with effective concentrations similar to those inhibiting photosynthesis. The agglomerated Ce

  4. Photodegradation of Paracetamol in Nitrate Solution

    Science.gov (United States)

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

    2010-11-01

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

  5. Photodegradation of Paracetamol in Nitrate Solution

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-24

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

  6. Photodegradation of Paracetamol in Nitrate Solution

    International Nuclear Information System (INIS)

    Meng Cui; Qu Ruijuan; Liang Jinyan; Yang Xi

    2010-01-01

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

  7. Determination of nitrate in effluents from Uranium Extraction Plant

    International Nuclear Information System (INIS)

    Dudwadkar, Ayushi; Kumar, Sangita D.; Reddy, A.V.R.

    2014-01-01

    Determination of nitrate concentration in the effluent samples from Uranium Extraction Plant is required before its safe discharge. As the different streams are diluted with sea water these samples contain high concentration of chloride. The large concentration of chloride poses a challenge in the determination of nitrate; hence, matrix elimination is accomplished by adopting a sample pretreatment technique. The present study was carried out to develop a simple, accurate and rapid analytical methodology for the determination of nitrate in the above matrices. The quantitative determination of nitrate was accomplished using anion exchange chromatography with conductometric detection. (author)

  8. Manurial properties of lead nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Berry, R A

    1924-01-01

    Water culture, pot and field experiments were conducted in order to determine the toxic and stimulating limit of lead nitrate in solution. Oats and rye grass were evaluated for evidence of lead poisoning. Results indicate that except in solutions of fairly high concentration, soil adsorbs the lead and destroys the toxicity of soluble lead salts. There was evidence to show that the addition of lead salts increased the rate of nitrification in soil.

  9. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    Science.gov (United States)

    Snow, Samantha J.; McGee, John; Miller, Desinia B.; Bass, Virginia; Schladweiler, Mette C.; Thomas, Ronald F.; Krantz, Todd; King, Charly; Ledbetter, Allen D.; Richards, Judy; Weinstein, Jason P.; Conner, Teri; Willis, Robert; Linak, William P.; Nash, David; Wood, Charles E.; Elmore, Susan A.; Morrison, James P.; Johnson, Crystal L.; Gilmour, Matthew Ian; Kodavanti, Urmila P.

    2014-01-01

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe results in greater adverse pulmonary effects compared with DE. Male Sprague Dawley rats were exposed to filtered air, DE, or DECe for 5 h/day for 2 days. N-acetyl glucosaminidase activity was increased in bronchial alveolar lavage fluid (BALF) of rats exposed to DECe but not DE. There were also marginal but insignificant increases in several other lung injury biomarkers in both exposure groups (DECe > DE for all). To further characterize DECe toxicity, rats in a second study were exposed to filtered air or DECe for 5 h/day for 2 days or 4 weeks. Tissue analysis indicated a concentration- and time-dependent accumulation of lung and liver cerium followed by a delayed clearance. The gas-phase and high concentration of DECe increased lung inflammation at the 2-day time point, indicating that gas-phase components, in addition to particles, contribute to pulmonary toxicity. This effect was reduced at 4 weeks except for a sustained increase in BALF γ-glutamyl transferase activity. Histopathology and transmission electron microscopy revealed increased alveolar septa thickness due to edema and increased numbers of pigmented macrophages after DECe exposure. Collectively, these findings indicate that DECe induces more adverse pulmonary effects on a mass basis than DE. In addition, lung accumulation of cerium, systemic translocation to the liver, and delayed clearance are added concerns to existing health effects of DECe. PMID:25239632

  10. Derivation of an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions

    International Nuclear Information System (INIS)

    Min, Duck Kee; Choi, Byung Il; Ro, Seung Gy; Eom, Tae Yoon; Kim, Zong Goo

    1986-01-01

    Densities of a large number of mixed uranyl nitrate-thorium nitrate solutions were measured with pycnometer. By the least squares analysis of the experimental result, an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions as functions of uranium concentration, thorium concentration and nitric acid normality is derived; W=1.0-0.3580 C u -0.4538 C Th -0.0307H + where W, C u , C Th , and H + stand for water content(g/cc), uranium concentration (g/cc), thorium concentration(g/cc), and nitric acid normality, respectively. Water contents of the mixed uranyl nitrate-thorium nitrate solutions are calculated by using the empirical formular, and compared with the values calculated by Bouly's equation in which an additional data, solution density, is required. The two results show good agreements within 2.7%. (Author)

  11. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Li; Shi, Jing, E-mail: shijing@ouc.edu.cn; Wang, Xin, E-mail: wangxin.hd@163.com; Liu, Dan; Xu, Haigang

    2016-07-15

    Graphical abstract: The unmodified coating shows averaged static water contact angles of a little more than 50º, which is clearly hydrophilic for water solutions. With the silane concentration increases, the water contact angles show an increase tendency. Especially, when the silane addition is increased to 25 ml L-1, the coating surface presents a hydrophobic feature, with static water contact angle of more than 110º. - Highlights: • BTESPT modification can effectively improve the uniformity, hydrophobic performance, chemical stability and corrosion inhibition capability of traditional cerium conversion coating. • Si-O-Si linkage builds a robust structure to increase of the coating density. Si−O−Mg bonds strengthen the adhesion between the coating/substrate. • The system modified with 25 ml L{sup −1} BTESPT displays the optimum corrosion protection performance. - Abstract: The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Si−O−Si and Si

  12. Microstructure and electrochemical behavior of cerium conversion coating modified with silane agent on magnesium substrates

    International Nuclear Information System (INIS)

    Lei, Li; Shi, Jing; Wang, Xin; Liu, Dan; Xu, Haigang

    2016-01-01

    Graphical abstract: The unmodified coating shows averaged static water contact angles of a little more than 50º, which is clearly hydrophilic for water solutions. With the silane concentration increases, the water contact angles show an increase tendency. Especially, when the silane addition is increased to 25 ml L-1, the coating surface presents a hydrophobic feature, with static water contact angle of more than 110º. - Highlights: • BTESPT modification can effectively improve the uniformity, hydrophobic performance, chemical stability and corrosion inhibition capability of traditional cerium conversion coating. • Si-O-Si linkage builds a robust structure to increase of the coating density. Si−O−Mg bonds strengthen the adhesion between the coating/substrate. • The system modified with 25 ml L"−"1 BTESPT displays the optimum corrosion protection performance. - Abstract: The cerium conversion coating with and without different concentrations of silane agent bis-(γ-triethoxysilylpropyl)-tetrasulfide (BTESPT) modification is obtained on magnesium alloys. Detailed properties of the coatings and the role of BTESPT as an additive are studied and followed with careful discussion. The coating morphology, wettability, chemical composition and corrosion resistance are characterized by scanning electronic microscope (SEM), water contact-angle, X-ray photoelectron spectroscopy (XPS), potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of the coatings is investigated using EIS. The results indicate that the coating morphology and composition can be controlled by changing silane concentration. The combination of cerium ions and silane molecules could promote the formation of more homogenous and higher hydrophobic coating. The coating turns to be more compact and the adhesive strength between the coating and the magnesium substrate are strongly improved with the formation of Si−O−Si and Si−O−M chemical

  13. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important

  14. Studies on the promotion of nickel—alumina coprecipitated catalysts: III. Cerium oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Slaa, J.C.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    Three series of cerium-promoted nickel—alumina catalysts with different nickel-to-aluminium ratios each containing different amounts of cerium have been prepared and characterized. The calcination and reduction behaviour were found not to be altered by the presence of cerium. Part of the promoter

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

    Science.gov (United States)

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

    2015-01-01

    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.

  16. Chlorination and Carbochlorination of Cerium Oxide

    International Nuclear Information System (INIS)

    Esquivel, Marcelo; Bohe, Ana; Pasquevich, Daniel

    2000-01-01

    The chlorination and carbochlorination of cerium oxide were studied by thermogravimetry under controlled atmosphere (TG) in the 700 0 C 950 0 C temperature range.Both reactants and products were analyzed by X-ray diffraction (RX), scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). Thermodynamic calculations were performed by computer assisted software.The chlorination starts at a temperature close to 800 0 C.This reaction involves the simultaneous formation and evaporation of CeCl3.Both processes control the reaction rate and their kinetic may not be easily separated.The apparent chlorination activation energy in the 850 0 C-950 0 C temperature range is 172 to 5 kJ/ mole.Carbon transforms the CeO2-Cl2 into a more reactive system: CeO2-C-Cl2, where the effects of the carbon content, total flow rate and temperature were analyzed.The carbochlorination starting temperature is 700 0 C.This reaction is completed in one step controlled by mass transfer with an apparent activation energy of 56 to 5 kJ/mole in the 850 0 C-950 0 C temperature range

  17. Stabilized zirconia with cerium and neodymium addition

    International Nuclear Information System (INIS)

    Andrade, I.M. de; Pessoa, R.C.; Nasar, M.C.; Nasar, R.S.; Rodriques, M.K.C.; Oliveira, J.F.

    2006-01-01

    Zr 0,9 Ce 0,05 Nd 0,05 O 1,975 system was synthesized with the use of the Pechini method. The polymeric resin was calcined at 350 deg C/3 h and analysed by FTIR that show bands relative to organic. Radicals esther type. The TGA curve indicated the polymeric decomposition occurring from 30 deg C to 740 deg C. DTA analysis show a exothermic peak in 100 deg C due to loss of water of material. From 500 deg C to 800 deg C was observed a intense peak due to polymer decomposition and the zirconia crystallization. The calcined powder from 350 deg C/3 h e 30 min to 900 deg/3 h were analysed by XRD that show the crystalline phase formation with the increase of temperature. The X-ray diffraction pattern show the presence of two phases, such as tetragonal and cubic of zirconia demonstrating that neodymium and cerium additions led to zirconia stabilization. (author)

  18. Environmental Geochemistry of Cerium: Applications and Toxicology of Cerium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jessica T. Dahle

    2015-01-01

    Full Text Available Cerium is the most abundant of rare-earth metals found in the Earth’s crust. Several Ce-carbonate, -phosphate, -silicate, and -(hydroxide minerals have been historically mined and processed for pharmaceutical uses and industrial applications. Of all Ce minerals, cerium dioxide has received much attention in the global nanotechnology market due to their useful applications for catalysts, fuel cells, and fuel additives. A recent mass flow modeling study predicted that a major source of CeO2 nanoparticles from industrial processing plants (e.g., electronics and optics manufactures is likely to reach the terrestrial environment such as landfills and soils. The environmental fate of CeO2 nanoparticles is highly dependent on its physcochemical properties in low temperature geochemical environment. Though there are needs in improving the analytical method in detecting/quantifying CeO2 nanoparticles in different environmental media, it is clear that aquatic and terrestrial organisms have been exposed to CeO2 NPs, potentially yielding in negative impact on human and ecosystem health. Interestingly, there has been contradicting reports about the toxicological effects of CeO2 nanoparticles, acting as either an antioxidant or reactive oxygen species production-inducing agent. This poses a challenge in future regulations for the CeO2 nanoparticle application and the risk assessment in the environment.

  19. Determination of the total nitrate content of thorium nitrate solution with a selective electrode

    International Nuclear Information System (INIS)

    Wirkner, F.M.

    1979-01-01

    The nitrate content of thorium nitrate solutions is determined with a liquid membrane nitrate selective electrode utilizing the known addition method in 0.1 M potassium fluoride medium as ionic strength adjustor. It is studied the influence of pH and the presence of chloride, sulphate, phosphate, meta-silicate, thorium, rare earths, iron, titanium, uranium and zirconium at the same concentrations as for the aqueous feed solutions in the thorium purification process. The method is tested in synthetic samples and in samples proceeding from nitric dissolutions of thorium hidroxide and thorium oxicarbonate utilized as thorium concentrates to be purified [pt

  20. Electrorefining of Cerium in LiCl-KCl Molten Salts

    International Nuclear Information System (INIS)

    Campbell-Kelly, R.P.; Paget, T.J.

    2010-01-01

    Electrorefining of cerium from cerium-gallium alloys has been demonstrated in lithium chloride-potassium chloride salts at temperatures below 500 deg. C, with excellent current efficiencies and high product yields. These experiments are being carried out as non-active trials for a process for the purification of impure actinide metals. The results reported show anodic current efficiencies consistently close to 100%, and in several experiments complete oxidation of the cerium in the feed occurred. The cathodic product is hard and metallic, and incorporates a significant amount of salt into its structure. The product can be consolidated into a dense, pure metal by melting under calcium chloride at 850 deg. C. The yield of this consolidation step varies between 16 and 75%, seeming to depend on the total mass of metal being consolidated and the quality of inert atmosphere. A small-scale electrochemical cell has been demonstrated which will be used in initial active experiments. (authors)

  1. Casting Characteristics of High Cerium Content Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, D; Rios, O R; Sims, Z C; McCall, S K; Ott, R T

    2017-09-05

    This paper compares the castability of the near eutectic aluminum-cerium alloy system to the aluminum-silicon and aluminum-copper systems. The alloys are compared based on die filling capability, feeding characteristics and tendency to hot tear in both sand cast and permanent mold applications. The castability ranking of the binary Al–Ce systems is as good as the aluminum-silicon system with some deterioration as additional alloying elements are added. In alloy systems that use cerium in combination with common aluminum alloying elements such as silicon, magnesium and/or copper, the casting characteristics are generally better than the aluminum-copper system. In general, production systems for melting, de-gassing and other processing of aluminum-silicon or aluminum-copper alloys can be used without modification for conventional casting of aluminum-cerium alloys.

  2. Chemiluminescence behavior based on oxidation reaction of rhodamine B with cerium(IV) in sulfuric acid medium

    International Nuclear Information System (INIS)

    Ma Yongjun; Jin Xiaoyong; Zhou Min; Zhang Ziyu; Teng Xiulan; Chen Hui

    2003-01-01

    The chemiluminescence (CL) of the rhodamine B (RhB)-cerium(IV) system was investigated by flow-injection. Rhodamine B was suggested to be a suitable chemiluminescent reagent in acidic conditions. When the concentration of rhodamine B was 100 mg l -1 and cerium sulfate was 1.6 mmol l -1 in sulfuric acid, the chemiluminescent intensity was found to be highest by using 0.3 mol l -1 sulfuric acid as a carrier solution. The particular chemiluminescent system could tolerate such distinct acidic environments that it was utilized for detecting many compounds that are stable in acidic solutions. Furthermore, by virtue of IR, UV-Vis and luminescence spectroscopic measurements, the chemiluminescent behavior of rhodamine B was studied and a possible mechanism for this chemiluminescent reaction was proposed. The emitter was affirmed to be a radical species due to one of the oxidation products of RhB; the chemiluminescent emissive wavelength was about 425 nm

  3. Characterization of the deviation of the ideality of concentrated electrolytic solutions: plutonium 4 and uranium 4 nitrate salts study; Contribution a la caracterisation de l'ecart a l'idealite des solutions concentrees d'electrolytes: application aux cas de nitrates de plutonium (4) et d'uranium (4)

    Energy Technology Data Exchange (ETDEWEB)

    Charrin, N

    2000-07-01

    The purpose of this work was to establish a new binary data base by compiling the activity coefficients of plutonium and uranium at oxidation state +IV to better account for media effects in the liquid-liquid extraction operations implemented to reprocess spent nuclear fuel. Chapter 1: first reviews the basic thermodynamic concepts before describing the issues involved in acquiring binary data for the tetravalent actinides. The difficulties arise from two characteristics of this type of electrolyte: its radioactive properties (high specific activity requiring nuclearization of the experimental instrumentation) and its physicochemical properties (strong hydrolysis). After defining the notion of fictive binary data, an approach based on the thermodynamic concept of simple solutions is described in which the activity coefficient of an aqueous phase constituent is dependent on two parameters: the water activity of the system and the total concentration of dissolved constituents. The method of acquiring fictive binary electrolyte data is based on water activity measurements for ternary or quaternary actinide mixtures in nitric acid media, and binary data for nitric acid. The experimental value is then correlated with the characteristics of the fictive binary solution of the relevant electrolyte. Chapter 2: proposes more reliable binary data for nitric acid than the published equivalents, the disparities of which are discussed. The validation of the method described in Chapter 1 for acquiring fictive binary data is then addressed. The test electrolyte, for which binary data are available in the literature, is thorium(IV) nitrate. The method is validated by comparing the published binary data obtained experimentally for binary solutions with the data determined for the ternary Th(NO{sub 3}){sub 4}/HNO{sub 3}/H{sub 2}O system investigated in this study. The very encouraging results of this comparison led us to undertake further research in this area. Chapter 3 discusses

  4. Cerium-modified Aurivillius-type sodium lanthanum bismuth titanate with enhanced piezoactivities

    International Nuclear Information System (INIS)

    Wang Chunming; Zhao Liang; Wang Jinfeng; Zheng Limei; Du Juan; Zhao Minglei; Wang Chunlei

    2009-01-01

    The electrical, piezoelectric and dielectric properties of cerium-modified Aurivillius-type sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) ceramics were investigated. It was found the piezoelectric activities of NLBT ceramics were significantly improved by cerium modification. The piezoelectric coefficient d 33 and Curie temperature T c for the 0.50 wt.% cerium-modified NLBT were found to be 29 pC/N and 573 deg. C, respectively. The reasons for piezoelectric activities improvement by cerium modification were given. A small dielectric abnormity was observed in NLBT ceramics, which can be suppressed by cerium modification.

  5. Synthesis and characterization of magnesium doped cerium oxide for the fuel cell application

    International Nuclear Information System (INIS)

    Kumar, Amit; Kumari, Monika; Kumar, Mintu; Kumar, Sacheen; Kumar, Dinesh

    2016-01-01

    Cerium oxide has attained much attentions in global nanotechnology market due to valuable application for catalytic, fuel additive, and widely as electrolyte in solid oxide fuel cell. Doped cerium oxide has large oxygen vacancies that allow for greater reactivity and faster ion transport. These properties make cerium oxide suitable material for SOFCs application. Cerium oxide electrolyte requires lower operation temperature which shows improvement in processing and the fabrication technique. In our work, we synthesized magnesium doped cerium oxide by the co-precipitation method. With the magnesium doping catalytic reactivity of CeO_2 was increased. Synthesized nanoparticle were characterized by the XRD and UV absorption techniques.

  6. Concentrations, sources and health effects of parent, oxygenated- and nitrated- polycyclic aromatic hydrocarbons (PAHs) in middle-school air in Xi'an, China

    Science.gov (United States)

    Wang, Jingzhi; Xu, Hongmei; Guinot, Benjamin; Li, Lijuan; Ho, Steven Sai Hang; Liu, Suixin; Li, Xiaoping; Cao, Junji

    2017-08-01

    Indoor and outdoor concentrations of polycyclic aromatic hydrocarbons (PAHs), oxygenated-PAHs (OPAHs), and nitro-PAHs (NPAHs) associated with PM2.5 particles were monitored in a middle-school classroom from 8 to 22 March 2012 in Xi'an, China. The total PAHs ranged from 49.6 to 140.0 ng/m3 in outdoors and 50.3 to 111.6 ng/m3 in indoors, while OPAHs and NPAHs showed averages of 19.1 and 16.4 ng/m3, 0.1039 and 0.0785 ng/m3 for outdoor and indoor air, respectively. Strong correlations were found between indoor (I) and outdoor (O), and the I/O ratios were school in Xi'an. Indoor pollutants were mostly influenced by outdoor air. Biomass burning, coal combustion, and vehicle emission were main sources for PAHs. Secondary formation was the main source for OPAHs and NPAHs. Inhalation cancer risks assessment of PAHs showed there were potential health risks for students during sampling time.

  7. Influence of annealing on texture properties of cerium oxide thin films

    International Nuclear Information System (INIS)

    Arunkumar, P.; Suresh Babu, K.; Ramaseshan, R.; Dash, S.

    2013-01-01

    Future power demand needs an energy source with higher efficiency, better power density, clean energy and fuel flexibility. Solid oxide fuel cell (SOFC) is one of the potential sources for future needs. Though the polymer and direct methanol based electrolyte are much suitable, for versatile applications (portable devices) they are having major challenges such as design, platinum based catalyst, lower power density and fuel flexibility (free from hydrocarbons). However, in SOFC the high operating temperature is the only major issue. Operating temperature of SOFC could be reduced by proper selection of electrolyte material which should have minimum ionic conductivity of 0.1 Scm -1 at reduced activation energy. This can be achieved by thin film based doped cerium oxide electrolyte for SOFC, leads to Intermediate Temperature Solid Oxide Fuel Cell (ITSOFC). In the present work, we focus on the synthesis of cerium oxide and 20 mol % samarium doped cerium oxide (SDC) nanoparticles by co-precipitation method and to synthesis thin films of the same. Pellets of those powders were heat treated at different temperatures and used as targets for e-beam evaporation to fabricate thin film based electrolyte. Stoichiometry of both powders and thin films were confirmed by XRF and EPMA. GIXRD profiles of ceria and SDC thin films are shown below and a preferred orientation effect is observed in SDC films. In SDC films the X-ray peaks have a shift towards lower angles, due to the difference in ionic radii of Ce 4+ and Sm 3+ . The band gap of CeO 2 (2.88 eV) from optical absorption technique indicates the presence of Ce 3+ with Ce 4+ , indirectly shows the concentration of oxygen vacancies which is required for the thin film electrolyte

  8. Selective anodic dissolution of cerium from aluminium alloys under potentiostatic conditions

    International Nuclear Information System (INIS)

    Gol'dshtejn, S.L.; Raspopin, S.P.; Seleznev, V.D.; Tunin, A.V.; Fedorov, V.A.

    1975-01-01

    A study was made of selective anodic dissolution of aluminum alloys containing cerium in concentrations from 0.5 to 10% by mass. The electropurification was carried out with the aid of a potentiostatic setup at 700 deg C in atmosphere of purified argon. Liquid aluminum served as the cathode, with chlorine half-cell as reference electrode and the melt of equimolar KCl-NaCl mixture as the electrolyte. The ''current-time'' plots are presented for selective ionization of cerium from aluminum alloys at preset potential values on the installation. For PHIsub(preset)=-2.04 v the current of potentiostatic electrolysis fades out to that of the supporting electrolyte, and the process itself proceeds at a rate that provides maximal extraction of cerium from the alloy (csub9finite)approximately equal to 0.002% by mass) at minimal ionization of the metalsolvent (Δ Msub(Al)approximately equal to 0.2). Alloys containing not less then 1% by mass of Ce exhibit a characteristic abrupt change of the attenuation coefficient apparently owing to nonlinear dependence of unbalance (ΔE) of signals at the input of the potentiostat. The ''ΔE-c'' function for Al alloy containing 0.5% by mass of Ce can be approximated by linear function. In this case the current of potentiostatic electrolysis approaches the value of the limiting diffusion current. To obtain the relationship between the magnitude of the limiting current of Ce ionization and the initial composition of the dissolving alloy, measurements were made under potentiodynamic conditions at a scanning rate of approximately equal to 500 mv/min. The results indicate that isub(intermediate) is directly proportional to csub(initial). It was shown that under the conditions employed, practically complete (csub(finite)<=0.004% by mass) extraction of the electronegative component is possible without noticeable ionization of the metal-solvent

  9. Management of Nitrate m Groundwater: A Simulation Study

    Directory of Open Access Journals (Sweden)

    M. Ahmed

    2001-01-01

    Full Text Available Agriculture may cause nitrate and other chemicals to enter into groundwater systems. Nitrate in drinking water is considered a health hazard. A study was conducted to assess the extent of nitrate pollution of groundwater caused by agriculture and to evaluate the possibility of using the LEACHN model to manage nitrate entry into groundwater of agricultural areas of Al-Batinah, which is the most important agricultural region of Oman. Groundwater samples were collected and analyzed to assess the problem and to detect possible trends. Soil sampling and analyses were done to demonstrate the difference in the nitrate concentration in agricultural and non-agricultural soils. A questionnaire survey was conducted to gather information on agricultural practices, fertilizer input, and other possible sources of nitrate pollution. Results from the study show that 23% of groundwater samples have a concentration of nitrate-N concentration of 10 mg/l and 34% samples exceed 8 mg/l. Agricultural soils have higher levels of nitrate compared to non- agricultural soils. Results also demonstrate that nitrate levels in groundwater in Al-Batinah are rising. Application of the ‘LEACHN’ model demonstrated its suitability for use as a management tool to reduce nitrate leaching to groundwater by controlling fertilizer and water input.

  10. Membrane assisted liquid-liquid extraction of cerium

    International Nuclear Information System (INIS)

    Soldenhoff, K.M.

    2000-02-01

    Membrane assisted liquid-liquid extraction of cerium was investigated, with emphasis placed on the study of the reaction chemistry and the kinetics of non-dispersive solvent extraction and stripping with microporous membranes. A bulk liquid membrane process was developed for the purification of cerium(IV) from sulfate solutions containing other rare earth elements. The cerium process was studied in both a flat sheet contained liquid membrane configuration and with hollow fibre contactors. Di-2-ethylhexyl phosphoric acid (DEHPA) was identified as a suitable extractant for cerium(IV) from sulfuric acid solution, with due consideration of factors such as extraction ability, resistance to degradation, solvent selectivity and potential for sulfate transfer into a strip solution. A detailed study of the extraction of cerium(IV) with DEHPA defined the extraction reaction chemistry. The Ce/DEHPA/sulfate system was also investigated with a flat sheet bulk liquid membrane configuration, using both sulfuric and hydrochloric acid as receiver solutions. These tests identified that hydrophobic membranes provide better mass transfer for extraction and hydrophilic membranes are better for stripping. The presence of an impurity, mono 2-ethylhexyl phosphoric acid (MEHPA), was found to have a dramatic accelerating effect on the rate of the chemical extraction reaction. This was attributed to its higher interfacial activity and population compared to DEHPA, and the fact that MEHPA was also found to be an active carrier for cerium(IV). The mass transfer rate of membrane assisted extraction and stripping of cerium, using hydrophobic and hydrophilic microporous membranes, respectively, was investigated using a modified Lewis-type cell. It was quantitatively demonstrated that the extraction process was mainly controlled by membrane diffusion and the stripping process was controlled by the chemical reaction rate, with membrane diffusion becoming important at low distribution coefficients

  11. Cerium-doped scintillating fused-silica fibers

    Science.gov (United States)

    Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P.; Faulkner, J.; Kunori, S.

    2018-04-01

    We report on a set of measurements made on (scintillating) cerium-doped fused-silica fibers using high-energy particle beams. These fibers were uniformly embedded in a copper absorber in order to utilize electromagnetic showers as a source of charged particles for generating signals. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters in high-energy physics, tracking systems, and beam monitoring detectors for future applications. The light yield, pulse shape, attenuation length, and light propagation speeds are given and discussed. Possible future applications are also explored.

  12. Spectrofluorimetric determination of cerium by flow injection analysis

    International Nuclear Information System (INIS)

    Liu Shaorong; Meng Jian; Liu Wenhua

    1990-01-01

    A spectrofluorimetric method for the determination of cerium (λ ex/em:251/365 nm) in hydrochloric acid solution by flow injection analysis is presented. It has well developed the normal spectrofluorimetric method for determination of cerium and has made: 1, the determination procedure shortened; 2, the determination speed increased to about 180 samples per hour; 3, the determination range widened to 0.05-100.0 ppm CeO 2 , abouot two times as wide as the normal spectrofluorimetric method; and 4, the relative standard deviation lessened (about 0.47% for 0.1 ppm CeO 2 , n = 13)

  13. Photochemical reduction of uranyl nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Duerksen, W.K.

    1993-10-20

    The photochemical reduction of uranyl nitrate solutions to tetravalent uranium was investigated as a means of producing uranium dioxide feed for the saltless direct oxide reduction (SDOR) process. At high uranium concentrations, reoxidation of U{sup +4} occurs rapidly. The kinetics of the nitric oxidation of tetravalent uranium depend on the concentrations of hydrogen ion, nitrate ion, nitrous acid, and tetravalent uranium in the same manner as was reported elsewhere for the nitrate oxidation of PU{sup +3}. Reaction rate data were successfully correlated with a mechanism in which nitrogen dioxide is the reactive intermediate. Addition of a nitrous acid scavenger suppresses the reoxidation reaction. An immersion reactor employing a mercury vapor lamp gave reduction times fast enough for routine production usage. Precipitation techniques for conversion of aqueous U(NO{sub 3}){sub 4} to hydrous UO{sub 2} were evaluated. Prolonged dewatering times tended to make the process time consuming. Use of 3- to 4-M aqueous NaOH gave the best dewatering times observed. Reoxidation of the UO{sub 2} by water of hydration was encountered, which required the drying process to be carried out under a reducing atmosphere.

  14. Cloning and nitrate induction of nitrate reductase mRNA

    OpenAIRE

    Cheng, Chi-Lien; Dewdney, Julia; Kleinhofs, Andris; Goodman, Howard M.

    1986-01-01

    Nitrate is the major source of nitrogen taken from the soil by higher plants but requires reduction to ammonia prior to incorporation into amino acids. The first enzyme in the reducing pathway is a nitrate-inducible enzyme, nitrate reductase (EC 1.6.6.1). A specific polyclonal antiserum raised against purified barley nitrate reductase has been used to immunoprecipitate in vivo labeled protein and in vitro translation products, demonstrating that nitrate induction increases nitrate reductase p...

  15. The evolution mechanism of the dislocation loops in irradiated lanthanum doped cerium oxide

    International Nuclear Information System (INIS)

    Miao, Yinbin; Aidhy, Dilpuneet; Chen, Wei-Ying; Mo, Kun; Oaks, Aaron; Wolf, Dieter; Stubbins, James F.

    2014-01-01

    Cerium dioxide, a non-radioactive surrogate of uranium dioxide, is useful for simulating the radiation responses of uranium dioxide and mixed oxide fuel (MOX). Controlled additions of lanthanum can also be used to form various levels of lattice oxide or anion vacancies. In previous transmission electron microscopy (TEM) experimental studies, the growth rate of dislocation loops in irradiated lanthanum doped ceria was reported to vary with lanthanum concentration. This work reports findings of the evolution mechanisms of the dislocation loops in cerium oxide with and without lanthanum dopants based on a combination of molecular statics and molecular dynamics simulations. These dislocation loops are found to be b=1/3〈111〉 interstitial type Frank loops. Calculations of the defect energy profiles of the dislocation loops with different structural configurations and radii reveal the basis for preference of nucleation as well as the driving force of growth. Frenkel pair evolution simulations and displacement cascade overlaps simulations were conducted for a variety of lanthanum doping conditions. The nucleation and growth processes of the Frank loop were found to be controlled by the mobility of cation interstitials, which is significantly influenced by the lanthanum doping concentration. Competition mechanisms coupled with the mobility of cation point defects were discovered, and can be used to explain the lanthanum effects observed in experiments

  16. Concentrations of nitrous acid, nitric acid, nitrite and nitrate in the gas and aerosol phase at a site in the emission zone during ESCOMPTE 2001 experiment

    Science.gov (United States)

    Acker, K.; Möller, D.; Auel, R.; Wieprecht, W.; Kalaß, D.

    2005-03-01

    Ground-based measurements were performed at the "Expérience sur Site pour COntraindre les Modèles de Pollution atmosphérique et de Transport d`Emissions" (ESCOMPTE) field site E3 (Realtor) about 30 km north of the urban environment of Marseille and east of the industrial centre Berre pond to investigate the formation of nitrous and nitric acid and to detect the distribution of reactive N-species between the gas and particle phase during photochemical pollution events. A wet denuder sampling for gases followed by a steam jet collection for aerosols was both coupled to anion chromatographic analysis. The analytical system provided data continuously with 30-min time resolution between June 13 and July 13, 2001. Indications for heterogeneous formation of nitrous acid during nighttime and daytime on ground and aerosol surfaces were found, the average HNO 2/NO 2 ratio was 6%. Highest concentrations were observed during two episodes of strong pollution accumulation when sea breeze transported industrial, traffic and urban pollution land-inwards. After nocturnal heterogeneous formation (about 0.1 ppb v h -1 were estimated corresponding to increasing HNO 2/NO 2 ratios) and accumulation processes up to 1.2 ppb v HNO 2 were observed. Their photolysis produces up to 5-9×10 6 OH cm -3 s -1 and will contribute significantly to initiation of the daily photochemistry in the lowest part of the troposphere. For the key tropospheric species, HNO 3 daily peaks up to 4 ppb v were detected.

  17. Observations on particulate organic nitrates and unidentified components of NOy

    DEFF Research Database (Denmark)

    Nielsen, T.; Egeløv, A.H.; Granby, K.

    1995-01-01

    A method to determine the total content of particulate organic nitrates (PON) has been developed and ambient air measurements of PON, NO, NO2, HNO3, peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), gas NOy and particulate inorganic nitrate have been performed in the spring and early...... summer al an agricultural site in Denmark and compared with measurements of ozone, H2O2, SO2, formic acid, acetic acid and methane sulphonic acid. The gas NOy detector determines the sum NO + NO2 + HNO2 + HNO3 + PAN + PPN + gas phase organic nitrates + 2 x N2O5 + NO3. The content of residual gas NOy...... = gas NOy + particulate inorganic nitrate). Residual gas NOy was much higher than the particulate fraction of organic nitrates (PON). PON was only 0.25 +/- 0.11% of concentrations of photochemical oxidants in connection with high-pressure systems suggesting atmospheric processes being the major source...

  18. Stepwise hydrochloric acid extraction of monazite hydroxides for the recovery of cerium lean rare earths, cerium, uranium and thorium

    International Nuclear Information System (INIS)

    Swaminathan, T.V.; Nair, V.R.; John, C.V.

    1988-01-01

    Monazite sand is normally processed by the caustic soda route to produce mixed rare earth chloride, thorium hydroxide and trisodium phosphate. Bulk of the mixed rare earth chloride is used for the preparation of FC catalysts. Recently some of the catalyst producers have shown preference to cerium depleted (lanthanum enriched) rare earth chloride rather than the natural rare earth chloride obtained from monazite. Therefore, a process for producing cerium depleted rare earth chloride, cerium, thorium and uranium from rare earth + thorium hydroxide obtained by treating monazite, based on stepwise hydrochloric acid extraction, was developed in the authors laboratory. The process involves drying of the mixed rare earth-thorium hydroxide cake obtained by monazite-caustic soda process followed by stepwise extraction of the dried cake with hydrochloric acid under specified conditions

  19. Agricultural nitrate pollution

    DEFF Research Database (Denmark)

    Anker, Helle Tegner

    2015-01-01

    Despite the passing of almost 25 years since the adoption of the EU Nitrates Directive, agricultural nitrate pollution remains a major concern in most EU Member States. This is also the case in Denmark, although a fairly strict regulatory regime has resulted in almost a 50 per cent reduction...

  20. Nitrate leaching index

    Science.gov (United States)

    The Nitrate Leaching Index is a rapid assessment tool that evaluates nitrate (NO3) leaching potential based on basic soil and climate information. It is the basis for many nutrient management planning efforts, but it has considerable limitations because of : 1) an oversimplification of the processes...

  1. Cerium phosphate nanotubes: synthesis, characterization and biosensing

    Science.gov (United States)

    Meng, Ling; Yang, Lige; Zhou, Bo; Cai, Chenxin

    2009-01-01

    Cerium phosphate (CeP) nanotubes have been synthesized and confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The 1D nanomaterial has a monoclinic crystal structure with a mean width of 15-20 nm and a length up to several micrometers. The nanotubes have been employed as electrode substrates for immobilization and direct electrochemistry of heme proteins/enzymes with myoglobin (Mb) as a model. The electrochemical characteristics of the Mb-CeP/GC electrode were studied by voltammetry. After being immobilized on the nanotubes, Mb can keep its natural structure and undergo effective direct electron transfer reaction with a pair of well-defined redox peaks at -(367 ± 3) mV (pH 7.5). The apparent electron transfer rate constant is (9.1 ± 1.4) s-1. The electrode displays good features in the electrocatalytic reduction of H2O2, and thus can be used as a biosensor for detecting the substrate with a low detection limit (0.5 ± 0.05 µM), a wide linear range (0.01-2 mM), high sensitivity (14.4 ± 1.2 µA mM-1), as well as good stability and reproducibility. CeP nanotubes can become a simple and effective biosensing platform for the integration of heme proteins/enzymes and electrodes, which can provide analytical access to a large group of enzymes for a wide range of bioelectrochemical applications.

  2. Cerium phosphate nanotubes: synthesis, characterization and biosensing

    International Nuclear Information System (INIS)

    Meng Ling; Yang Lige; Zhou Bo; Cai Chenxin

    2009-01-01

    Cerium phosphate (CeP) nanotubes have been synthesized and confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The 1D nanomaterial has a monoclinic crystal structure with a mean width of 15-20 nm and a length up to several micrometers. The nanotubes have been employed as electrode substrates for immobilization and direct electrochemistry of heme proteins/enzymes with myoglobin (Mb) as a model. The electrochemical characteristics of the Mb-CeP/GC electrode were studied by voltammetry. After being immobilized on the nanotubes, Mb can keep its natural structure and undergo effective direct electron transfer reaction with a pair of well-defined redox peaks at -(367 ± 3) mV (pH 7.5). The apparent electron transfer rate constant is (9.1 ± 1.4) s -1 . The electrode displays good features in the electrocatalytic reduction of H 2 O 2 , and thus can be used as a biosensor for detecting the substrate with a low detection limit (0.5 ± 0.05 μM), a wide linear range (0.01-2 mM), high sensitivity (14.4 ± 1.2 μA mM -1 ), as well as good stability and reproducibility. CeP nanotubes can become a simple and effective biosensing platform for the integration of heme proteins/enzymes and electrodes, which can provide analytical access to a large group of enzymes for a wide range of bioelectrochemical applications.

  3. Effect of ultrasound treatment on the morpho-structural and luminescent characteristics of cerium doped yttrium silicate phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Silipas, D.T. [National Institute for R& D of Isotopic and Molecular Technologies, Donath 67-103, 400293 Cluj-Napoca (Romania); Tudoran, L. Barbu [Electronic Microscopy Centre, Babeş Bolyai University, Clinicilor 37, 400006 Cluj-Napoca (Romania)

    2015-08-15

    Highlights: • Y{sub 2}SiO{sub 5}:Ce is prepared by gel combustion in ultrasound conditions (US). • Morpho-structural characteristics are revealed based on FTIR, SEM, XRD, BET. • Incorporation of Ce{sup 3+} in X1/X2 type centers depends on preparative conditions. • US treatment increases the luminescent performances up to 151%. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by gel-combustion, using yttrium–cerium nitrate as oxidizer, aspartic acid as fuel and TEOS as source of silicon. Two modalities for samples preparation were approached namely: the classical gel-combustion and sonication gel-combustion. The ultrasound treatment during the gelling stage has a positive effect on the structural and luminescent characteristics of the final product. Therefore, a well crystallized single X2–Y{sub 2}SiO{sub 5} phase phosphor was obtained at 1200 °C. Based on FT-IR and XRD investigations, conversion of X1 to X2–Y{sub 2}SiO{sub 5} phases is observed as the firing temperature is varied (1100 °C, 1200 °C, 1300 °C 1400 °C). The ultrasound treatment leads to smaller particle size and enhances the luminescent performances up to 151% in comparison with samples prepared by classical way.

  4. Comparative Study of Magnetic Instabilities in Cerium Compounds

    International Nuclear Information System (INIS)

    Pedrazzini, Pablo

    2003-01-01

    The variety of new phases and physical phenomena discovered in intermetallic compounds containing Rare Earths or Actinides has motivated, during the last four decades, the sustained study of their magnetic phase diagrams.The current interest is focused on the investigation of the region of the phase diagram where the magnetic order of Cerium, Ytterbium and Uranium based systems is destabilized.In this region different behaviours have been detected, such as non conventional superconductivity and the anomalous dependencies of the thermal, magnetic and transport properties at very low temperatures, associated to non-Fermi liquid behaviour.A simple model, the Doniach diagram, has guided the interpretation of the destabilization of the magnetic order in the previously mentioned systems.However, most of the systems that have been studied so far cannot be described within this model.This fact has motivated the development of a phenomenological classification of phase diagrams that has been mostly applied to cerium based compounds.This classification defines three types of phase diagrams, that can be distinguished by the way in which the magnetic transition is suppressed when a control parameter (such as doping or pressure) is driven towards its critical value.Within this scenario, we study the suppression of the antiferromagnetic order of the intermetallic compounds CeIn 3 , CeRh 2 Si 2 and CePd 2 Al 3 as a function of Ce-ligand alloying.The resulting systems, CeIn 3-x Sn x , Ce(Cu x Rh 1-x ) 2 Si 2 and CePd 2-x Ni x Al 3 , present different crystalline structures and the effects produced by the alloying process are different in each case.We analyse the resulting magnetic phase diagrams, and compare them with the above mentioned phenomenological classification.With such a purpose, we study in detail the region in which the magnetic instability takes place, in the proximity of the respective critical concentrations.Taking into account both our results and those reported in

  5. Nitrate in groundwater of the United States, 1991-2003

    Science.gov (United States)

    Burow, Karen R.; Nolan, Bernard T.; Rupert, Michael G.; Dubrovsky, Neil M.

    2010-01-01

    An assessment of nitrate concentrations in groundwater in the United States indicates that concentrations are highest in shallow, oxic groundwater beneath areas with high N inputs. During 1991-2003, 5101 wells were sampled in 51 study areas throughout the U.S. as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program. The well networks reflect the existing used resource represented by domestic wells in major aquifers (major aquifer studies), and recently recharged groundwater beneath dominant land-surface activities (land-use studies). Nitrate concentrations were highest in shallow groundwater beneath agricultural land use in areas with well-drained soils and oxic geochemical conditions. Nitrate concentrations were lowest in deep groundwater where groundwater is reduced, or where groundwater is older and hence concentrations reflect historically low N application rates. Classification and regression tree analysis was used to identify the relative importance of N inputs, biogeochemical processes, and physical aquifer properties in explaining nitrate concentrations in groundwater. Factors ranked by reduction in sum of squares indicate that dissolved iron concentrations explained most of the variation in groundwater nitrate concentration, followed by manganese, calcium, farm N fertilizer inputs, percent well-drained soils, and dissolved oxygen. Overall, nitrate concentrations in groundwater are most significantly affected by redox conditions, followed by nonpoint-source N inputs. Other water-quality indicators and physical variables had a secondary influence on nitrate concentrations.

  6. Anaerobic columnar denitrification of high nitrate wastewater

    International Nuclear Information System (INIS)

    Francis, C.W.; Malone, C.D.

    1975-01-01

    Anaerobic columns were used to test the effectiveness of biological denitrification of nitrate solutions ranging in concentration from 1 to 10 kg NO 3 /m 3 . Several sources of nitrate (Ca(CNO 3 ) 2 , NaNO 3 , NH 4 NO 3 , and actual nitrate wastes from a UO 2 fuel fabrication plant) were evaluated as well as two packing media. The packing media were anthracite coal particles, whose effective diameter size ranged between 2 and 3 mm, and polypropylene Raschig rings 1.6 x 1.6 diameter. The anthracite coal proved to be the better packing media as excessive hydraulic short circuiting occurred in a 120 x 15 cm diameter glass column packed with the polypropylene rings after 40 days operation. With anthracite coal, floatation of the bed occurred at flow rates greater than 0.80 cm 3 /s. Tapered columns packed with anthracite coal eliminated the floatation problem, even at flow rates as high as 5 cm 3 /s. Under optimum operating conditions the anthracite coal behaved as a fluidized bed. Maximum denitrification rates were 1.0--1.4 g NO 3 /m 3 /s based on initial bed volume. Denitrification kinetics indicated that rates of denitrification became substrate inhibited at nitrate concentrations greater than 6.5 kg NO 3 /m 3 Anaerobic columns packed with anthracite coal appear to be an effective method of nitrate disposal for nitrate rich wastewater generated at UO 2 fuel fabrication plants and fuel reprocessing facilities. (U.S.)

  7. Thermoluminescence of cerium and terbium -doped calcium pyrophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Roman L, J.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Lozano R, I. B.; Diaz G, J. A. I., E-mail: jesus.roman@nucleares.unam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico)

    2015-10-15

    The aim of this work is to report the thermoluminescence (Tl) response of Calcium Pyrophosphate phosphor doped with Cerium and Terbium impurities (Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+}). The phosphors were synthesized using the co-precipitation method and annealed at 900 degrees C by two hours for obtain the β phase. The intentional doping with Ce and Tb ions was 1 at.% and 0.1 at.%, whereas in the EDS results the concentration of impurities was 0.39 at.% and 0.05 at.%, respectively. The superficial morphology of phosphor is mainly composed by thin wafers of different size. All samples were exposed to gamma rays from {sup 60}Co in the Gammacell-200 irradiator. The Tl response of the phosphor was measured from Rt up to 350 degrees C and under nitrogen atmosphere in a Harshaw TLD 3500 reader. The glow curves of the Ca{sub 2}P{sub 2}O{sub 7}:Ce{sup 3+},Tb{sup 3+} powders showed a broad intense Tl peak centered at 165 degrees C and a shoulder at approximate 260 degrees C was observed. A linear Tl response in the range of absorbed dose of 0.2 to 10 Gy was obtained. Tl glow curves were analyzed using the initial rise (IR)and computerized glow curve deconvolution methods to evaluate the kinetics parameters such as activation energy (E), frequency factor (s) and kinetic order (b). (Author)

  8. Effects of Cerium Oxide Nanoparticles on Sorghum Plant Traits

    Science.gov (United States)

    Mu, L.; Chen, Y.; Darnault, C. J. G.; Rauh, B.; Kresovich, S.; Korte, C.

    2015-12-01

    Nanotechnology and nanomaterials are considered as the development of the modern science. However, besides with that wide application, nanoparticles arouse to the side effects on the environment and human health. As the catalyst of ceramics and fuel industry, Cerium (IV) oxide nanoparticles (CeO2 NPs) can be found in the environment following their use and life-cycle. Therefore, it is critical to assess the potential effects that CeO2 NPs found in soils may have on plants. In this study, CeO2 NPs were analyzed for the potential influence on the sorghum [Sorghum bicolor (L.) Moench] (Reg. no. 126) (PI 154844) growth and traits. The objectives of this research were to determine whether CeO2 NPs impact the sorghum germination and growth characteristics. The sorghum was grown in the greenhouse located at Biosystems Research Complex, Clemson University under different CeO2 NPs treatments (0mg; 100mg; 500mg; 1000mg CeO2 NPs/Kg soil) and harvested around each month. At the end of the each growing period, above ground vegetative tissue was air-dried, ground to 2mm particle size and compositional traits estimated using near-infrared spectroscopy. Also, the NPK value of the sorghum tissue was tested by Clemson Agriculture Center. After the first harvest, the result showed that the height of above ground biomass under the nanoparticles stress was higher than that of control group. This difference between the control and the nanoparticles treatments was significant (F>F0.05; LSD). Our results also indicated that some of the compositional traits were impacted by the different treatments, including the presence and/or concentrations of the nanoparticles.

  9. High dose potassium-nitrate chemical dosimeter

    International Nuclear Information System (INIS)

    Dorda de Cancio, E.M.; Munoz, S.S.

    1982-01-01

    This dosimeter is used to control 10 kGY-order doses (1 Mrad). Nitrate suffers a radiolitic reduction phenomena, which is related to the given dose. The method to use potassium nitrate as dosimeter is described, as well as effects of the temperature of irradiation, pH, nitrate concentration and post-irradiation stability. Nitrate powder was irradiated at a Semi-Industrial Plant, at Centro Atomico Ezeiza, and also in a Gammacell-220 irradiator. The dose rates used were 2,60 and 1,80 KGY/hour, and the given doses varied between 1,0 and 150 KGY. The uncertainty was +-3% in all the range. (author) [es

  10. Nanoparticulate cerium dioxide and cerium dioxide-titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition

    International Nuclear Information System (INIS)

    Qureshi, Uzma; Dunnill, Charles W.; Parkin, Ivan P.

    2009-01-01

    Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)-nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV-visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO 2 nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

  11. A 5-day method for determination of soluble silicon concentrations in nonliquid fertilizer materials using a sodium carbonate-ammonium nitrate extractant followed by visible spectroscopy with heteropoly blue analysis: single-laboratory validation.

    Science.gov (United States)

    Sebastian, Dennis; Rodrigues, Hugh; Kinsey, Charles; Korndörfer, Gaspar; Pereira, Hamilton; Buck, Guilherme; Datnoff, Lawrence; Miranda, Stephen; Provance-Bowley, Mary

    2013-01-01

    A 5-day method for determining the soluble silicon (Si) concentrations in nonliquid fertilizer products was developed using a sodium carbonate (Na2CO3)-ammonium nitrate (NH4NO3) extractant followed by visible spectroscopy with heteropoly blue analysis at 660 nm. The 5-Day Na2CO3-NH4NO3 Soluble Si Extraction Method can be applied to quantify the plant-available Si in solid fertilizer products at levels ranging from 0.2 to 8.4% Si with an LOD of 0.06%, and LOQ of 0.20%. This Si extraction method for fertilizers correlates well with plant uptake of Si (r2 = 0.96 for a range of solid fertilizers) and is applicable to solid Si fertilizer products including blended products and beneficial substances. Fertilizer materials can be processed as received using commercially available laboratory chemicals and materials at ambient laboratory temperatures. The single-laboratory validation of the 5-Day Na2CO3-NH4NO3 Soluble Si Extraction Method has been approved by The Association of American Plant Food Control Officials for testing nonliquid Si fertilizer products.

  12. Safety aspects of solvent nitration in HTGR fuel reprocessing

    International Nuclear Information System (INIS)

    Wilbourn, R.G.

    1977-06-01

    Reprocessing of HTGR fuels requires evaporative concentration of uranium and thorium nitrate solutions. The results of a bench-scale test program conducted to assess the safety aspects of planned concentrator operations are reported

  13. Sustainability of natural attenuation of nitrate in agricultural aquifers

    Science.gov (United States)

    Green, Christopher T.; Bekins, Barbara A.

    2010-01-01

    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.

  14. Nitrate, Nitrite, and Ammonium Variability in Drinking Water Distribution Systems.

    Science.gov (United States)

    Schullehner, Jörg; Stayner, Leslie; Hansen, Birgitte

    2017-03-09

    Accurate assessments of exposure to nitrate in drinking water is a crucial part of epidemiological studies investigating long-term adverse human health effects. However, since drinking water nitrate measurements are usually collected for regulatory purposes, assumptions on (1) the intra-distribution system variability and (2) short-term (seasonal) concentration variability have to be made. We assess concentration variability in the distribution system of nitrate, nitrite, and ammonium, and seasonal variability in all Danish public waterworks from 2007 to 2016. Nitrate concentrations at the exit of the waterworks are highly correlated with nitrate concentrations within the distribution net or at the consumers' taps, while nitrite and ammonium concentrations are generally lower within the net compared with the exit of the waterworks due to nitrification. However, nitrification of nitrite and ammonium in the distribution systems only results in a relatively small increase in nitrate concentrations. No seasonal variation for nitrate, nitrite, or ammonium was observed. We conclude that nitrate measurements taken at the exit of the waterworks are suitable to calculate exposures for all consumers connected to that waterworks and that sampling frequencies in the national monitoring programme are sufficient to describe temporal variations in longitudinal studies.

  15. Combined ion exchange / biological denitrification for nitrate removal from ground water

    NARCIS (Netherlands)

    Hoek, van der J.P.

    1988-01-01

    This thesis deals with the development of a new process for nitrate removal from ground water. High nitrate concentrations in ground water are a result of fertilization in agriculture. According to a directive of the European Community the maximum admissible concentration of nitrate in

  16. Chronic nitrate exposure alters reproductive physiology in fathead minnows.

    Science.gov (United States)

    Kellock, Kristen A; Moore, Adrian P; Bringolf, Robert B

    2018-01-01

    Nitrate is a ubiquitous aquatic pollutant that is commonly associated with eutrophication and dead zones in estuaries around the world. At high concentrations nitrate is toxic to aquatic life but at environmental concentrations it has also been purported as an endocrine disruptor in fish. To investigate the potential for nitrate to cause endocrine disruption in fish, we conducted a lifecycle study with fathead minnows (Pimephales promelas) exposed to nitrate (0, 11.3, and 56.5 mg/L (total nitrate-nitrogen (NO 3 -N)) from nitrate-exposed males both 11-KT and vitellogenin were significantly induced when compared with controls. No significant differences occurred for body mass, condition factor, or GSI among males and intersex was not observed in any of the nitrate treatments. Nitrate-exposed females also had significant increases in vitellogenin compared to controls but no significant differences for mass, condition factor, or GSI were observed in nitrate exposed groups. Estradiol was used as a positive control for vitellogenin induction. Our findings suggest that environmentally relevant nitrate levels may disrupt steroid hormone synthesis and/or metabolism in male and female fish and may have implications for fish reproduction, watershed management, and regulation of nutrient pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Phase segregation in cerium-lanthanum solid solutions

    NARCIS (Netherlands)

    Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

    2006-01-01

    Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

  18. Effect of cerium and thermomechanical processing on microstructure

    Indian Academy of Sciences (India)

    The effect of cerium content and thermomechanical processing on structure and properties of Fe–10.5 wt.%Al–0.8 wt%C alloy has been investigated. Alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). The ESR ingots were hot-forged and hotrolled at ...

  19. Processing and Characterization of Sol-Gel Cerium Oxide Microspheres

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Zachary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Padilla Cintron, Cristina [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-27

    Of interest to space exploration and power generation, Radioisotope Thermoelectric Generators (RTGs) can provide long-term power to remote electronic systems without the need for refueling or replacement. Plutonium-238 (Pu-238) remains one of the more promising materials for thermoelectric power generation due to its high power density, long half-life, and low gamma emissions. Traditional methods for processing Pu-238 include ball milling irregular precipitated powders before pressing and sintering into a dense pellet. The resulting submicron particulates of Pu-238 quickly accumulate and contaminate glove boxes. An alternative and dust-free method for Pu-238 processing is internal gelation via sol-gel techniques. Sol-gel methodology creates monodisperse and uniform microspheres that can be packed and pressed into a pellet. For this study cerium oxide microspheres were produced as a surrogate to Pu-238. The similar electronic orbitals between cerium and plutonium make cerium an ideal choice for non-radioactive work. Before the microspheres can be sintered and pressed they must be washed to remove the processing oil and any unreacted substituents. An investigation was performed on the washing step to find an appropriate wash solution that reduced waste and flammable risk. Cerium oxide microspheres were processed, washed, and characterized to determine the effectiveness of the new wash solution.

  20. Purification of cerium, neodymium and gadolinium for low background experiments

    Directory of Open Access Journals (Sweden)

    Boiko R.S.

    2014-01-01

    Full Text Available Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search, 136Ce (2β+ candidate with one of the highest Q2β. The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  1. Gas sensing behaviour of cerium oxide and magnesium aluminate

    Indian Academy of Sciences (India)

    Gas sensing behaviour of cerium oxide and magnesium aluminate composites ... A lone pairof the electron state was identified from the electro paramagnetic ... carbon monoxide (CO) (at 0.5, 1.0 and 1.5 bar) and ethanol (at 50 and 100 ppm) was ... The magnitude of the temperature varied linearly regardless of the gas ...

  2. Cerium; crystal structure and position in the periodic table.

    Science.gov (United States)

    Johansson, Börje; Luo, Wei; Li, Sa; Ahuja, Rajeev

    2014-09-17

    The properties of the cerium metal have intrigued physicists and chemists for many decades. In particular a lot of attention has been directed towards its high pressure behavior, where an isostructural volume collapse (γ phase → α phase) has been observed. Two main models of the electronic aspect of this transformation have been proposed; one where the 4f electron undergoes a change from being localized into an itinerant metallic state, and one where the focus is on the interaction between the 4f electron and the conduction electrons, often referred to as the Kondo volume collapse model. However, over the years it has been repeatedly questioned whether the cerium collapse really is isostructural. Most recently, detailed experiments have been able to remove this worrisome uncertainty. Therefore the isostructural aspect of the α-γ transition has now to be seriously addressed in the theoretical modeling, something which has been very much neglected. A study of this fundamental characteristic of the cerium volume collapse is made in present paper and we show that the localized [rlhar2 ] delocalized 4f electron picture provides an adequate description of this unique behavior. This agreement makes it possible to suggest that an appropriate crossroad position for cerium in The Periodic Table.

  3. A phosphate-dependent shift in redox state of cerium oxide nanoparticles and its effects on catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sanjay; Dosani, Talib; Karakoti, Ajay S.; Kumar, Amit; Seal, Sudipta; Self, William

    2011-10-01

    Cerium oxide nanoparticles (CeNPs) have shown promise as catalytic antioxidants in cell culture and animal models as both superoxide dismutase and catalase mimetics. The reactivity of the cerium (Ce) atoms at the surface of its oxide particle is critical to such therapeutic properties, yet little is known about the potential for a protein or small molecule corona to form on these materials in vivo. Moreover Ce atoms in these active sites have the potential to interact with small molecule anions, peptides, or sugars when administered in culture or animal models. Several nanomaterials have been shown to alter or aggregate under these conditions, rendering them less useful for biomedical applications. In this work we have studied the change in catalytic properties of CeNPs when exposed to various biologically relevant conditions in vitro. We have found that CeNPs are resistant to broad changes in pH and also not altered by incubation in cell culture medium. However to our surprise phosphate anions significantly altered the characteristics of these nanomaterials and shifted the catalytic behavior due to the binding of phosphate anions to cerium. Given the abundance of phosphate in biological systems in an inorganic form, it is likely that the action of CeNPs as a catalyst may be strongly influenced by the local concentration of phosphate in the cells and/or tissues in which it has been introduced.

  4. Complexes of pentavalent plutonium in lithium nitrate solutions

    International Nuclear Information System (INIS)

    Mekhail, F.M.; Zaki, M.R.

    1977-01-01

    Pu 0 2 ion can form nitrate complexes in concentrated solution of lithium nitrate of PH 3.5. Spectrophotometric and ion exchange studies revealed the existence of two complexes, presumably the mono-and the dinitro. The rate of adsorption of the dinitrato complex, formed in 4 to 6 M-lithium nitrate solutions, on De-Acidite FF has been investigated and suggested to be diffusion controlled. The adsorption isotherm found to obey satisfactorily Freundlich equation

  5. Sodium nitrate combustion limit tests

    International Nuclear Information System (INIS)

    Beitel, G.A.

    1976-04-01

    Sodium nitrate is a powerful solid oxidant. Energetically, it is capable of exothermically oxidizing almost any organic material. Rate-controlling variables such as temperature, concentration of oxidant, concentration of fuel, thermal conductivity, moisture content, size, and pressure severely limit the possibility of a self-supported exothermic reaction (combustion). The tests reported in this document were conducted on one-gram samples at atmospheric pressure. Below 380 0 C, NaNO 3 was stable and did not support combustion. At moisture concentrations above 22 wt percent, exothermic reactions did not propagate in even the most energetic and reactive compositions. Fresh resin and paraffin were too volatile to enable a NaNO 2 -supported combustion process to propagate. Concentrations of NaNO 3 above 95 wt percent or below 35 wt percent did not react with enough energy release to support combustion. The influence of sample size and confining pressure, both important factors, was not investigated in this study

  6. Micrometeorological measurement of the dry deposition flux of sulphate and nitrate aerosols to coniferous forest

    NARCIS (Netherlands)

    Wyers, G.P.; Duyzer, J.H.

    1997-01-01

    Dry deposition fluxes of sulphate and nitrate have been determined over a coniferous canopy using the aerodynamic gradient technique. Vertical concentration gradients of sulphate and nitrate were measured with filters; the gradient of ammonium bisulphate was measured with thermodenuders. Filter

  7. In situ nitrate from groundwater using freely available carbon material at an industrially polluted site

    CSIR Research Space (South Africa)

    Israel, S

    2011-09-01

    Full Text Available concentrations, nitrate in drinking water can be toxic to infants and young animals. In situ treatment could be a robust and effective technique for removal of nitrate, iron and manganese....

  8. Checking Trace Nitrate in Water and Soil Using an Amateur Scientist's Measurement Guide.

    Science.gov (United States)

    Baker, Roger C. Jr.

    1995-01-01

    Presents a test that can measure nitrate nitrogen ions at about 0.1 mg/L using concentration. Uses inexpensive accessible materials and can be used by amateur environmentalists for monitoring water nitrate levels. (JRH)

  9. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    International Nuclear Information System (INIS)

    Gupta, Surbhi; Tomar, Monika; Gupta, Vinay

    2015-01-01

    The influence of Cerium doping on the structural and magnetic properties of BiFeO 3 thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi 1−x Ce x FeO 3 (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm −1 ) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm −1 ), shows a minor shift. Sudden evolution of Raman mode at 668 cm −1 , manifested as A 1 -tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M s ) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi 0.88 Ce 0.12 FeO 3 thin film found to exhibit better magnetic properties with M s =15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi 1−x Ce x FeO 3 thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical applications of such materials exhibiting pinching behavior are conferred

  10. Magnetic hysteresis of cerium doped bismuth ferrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Surbhi [Department of Physics and Astrophysics, University of Delhi (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi (India)

    2015-03-15

    The influence of Cerium doping on the structural and magnetic properties of BiFeO{sub 3} thin films have been investigated. Rietveld refinement of X-ray diffraction data and successive de-convolution of Raman scattering spectra of Bi{sub 1−x}Ce{sub x}FeO{sub 3} (BCFO) thin films with x=0–0.20 reflect the single phase rhombohedral (R3c) formation for x<0.08, whereas concentration-driven gradual structural phase transition from rhombohedral (R3c) to partial tetragonal (P4mm) phase follows for x≥0.08. All low wavenumber Raman modes (<300 cm{sup −1}) showed a noticeable shift towards higher wavenumber with increase in doping concentration, except Raman E-1 mode (71 cm{sup −1}), shows a minor shift. Sudden evolution of Raman mode at 668 cm{sup −1}, manifested as A{sub 1}-tetragonal mode, accompanied by the shift to higher wavenumber with increase in doping concentration (x) affirm partial structural phase transition. Anomalous wasp waist shaped (M–H) hysteresis curves with improved saturation magnetization (M{sub s}) for BCFO thin films is attributed to antiferromagnetic interaction/hybridization between Ce 4f and Fe 3d electronic states. The contribution of both hard and soft phase to the total coercivity is calculated. Polycrystalline Bi{sub 0.88}Ce{sub 0.12}FeO{sub 3} thin film found to exhibit better magnetic properties with M{sub s}=15.9 emu/g without any impure phase. - Highlights: • Synthesis of single phase Bi{sub 1−x}Ce{sub x}FeO{sub 3} thin films with (x=0–0.2) on cost effective corning glass and silicon substrates using CSD technique. • Structural modification studies using Rietveld refinement of XRD and de-convolution of Raman spectra revealed partial phase transition from rhombohedral (R3c) to tetragonal (P4mm) phase. • Possible reasons for origin of pinched magnetic behavior of BCFO thin films are identified. • Contribution of both hard and soft magnetic phase in coercivity of BCFO thin films is calculated and practical

  11. Factors controlling nitrate cracking of mild steel

    International Nuclear Information System (INIS)

    Donovan, J.A.

    1977-01-01

    Nitrite and hydroxide ions inhibit the growth of nitrate stress corrosion cracks in mild steel. Crack growth measurements showed that sufficient concentrations of nitrite and hydroxide ions can prevent crack growth; however, insufficient concentrations of these ions did not influence the Stage II growth rate or the threshold stress intensity, but extended the initiation time. Stage III growth was discontinuous. Oxide formed in the grain boundaries ahead of the crack tip and oxide dissolution (Stage II) and fracture (Stage III) are the proposed mechanisms of nitrate stress corrosion crack growth

  12. Nitrate pollution and its distribution in the groundwater of Srikakulam district, Andhra Pradesh, India

    Science.gov (United States)

    Rao, Nagireddi Srinivasa

    2006-12-01

    The complex depositional pattern of clay and sand in most of the areas controlled the vertical and lateral movement of nitrate in groundwater. The variation of nitrate concentration at different groundwater levels and the lateral distribution of nitrate in the groundwater at two sites indicated the filtration of nitrate by clayey formations. A rural agricultural district located in the Vamsadhara river basin, India was selected for studying the lateral and vertical distribution of nitrate in the groundwater and the association of nitrate with other chemical constituents. The nitrate concentrations in the groundwater are observed to vary between below detectable limit and 450 mg NO3/L. The sources for nitrate are mainly point sources (poultry farms, cattleshed and leakages from septic tanks) and non-point sources (nitrogenous fertilisers). The nitrate concentrations are increased after fertiliser applications. However, very high concentrations of nitrate are derived from animal wastes. Relatively better correlations between nitrate and potassium are observed ( R = 0.74 to 0.82). The better relationship between these two chemical constituents in the groundwater may be due to the release of potassium and nitrate from both point and non-point sources. The nitrate and potassium concentrations are high in the groundwater from clayey formations.

  13. Properties of concentrated plutonium nitrate solutions

    International Nuclear Information System (INIS)

    Gray, J.H.; Swanson, J.L.

    1978-01-01

    Selected properties were measured for solutions containing about 500 and 700 g/l plutonium (IV) in 4--5M nitric acid: density, viscosity, vapor pressure, boiling point, radiolytic gas (H 2 ) evolution rates, and corrosion rate on Ti and 304L stainless steel. Pu solubility was determined to be 550 to 800 g/l in 2.5 to 7M HNO 3 at ambient temperature and 820 to 860 g/l in 3M HNO 3 at 50 0 C

  14. Using Nitrate Isotopes to Distinguish Pathways along which Unprocessed Atmospheric Nitrate is Transported through Forests to Streams

    Science.gov (United States)

    Sebestyen, S. D.

    2013-12-01

    Evaluation of natural abundance oxygen and nitrogen isotopes in nitrate has revealed that atmospheric deposition of nitrate to forests sometimes has direct effects on the timing and magnitude of stream nitrate concentrations. Large amounts of unprocessed atmospheric nitrate have sometimes been found in streams during snowmelt and stormflow events. Despite increasing evidence that unprocessed atmospheric nitrate may be transported without biological processing to streams at various times and multiple locations, little has been reported about specific hydrological processes. I synthesized research findings from a number of studies in which nitrate isotopes have been measured over the past decade. Unprocessed nitrate may predominate in surficial soil waters after rainfall and snowmelt events relative to nitrate that originated from nitrification. Although transport to deep groundwater may be important in the most nitrogen saturated catchments, the transport of unprocessed atmospheric nitrate along shallow subsurface flowpaths is likely more important in many moderately N-polluted ecosystems, which predominate in the northeastern USA where most of my study sites are located. The presence of unprocessed atmospheric nitrate in surficial soils was linked to stream nitrate concentrations when large amounts of unprocessed nitrate were occasionally routed along lateral, shallow subsurface flowpaths during stormflow events. During these events, water tables rose to saturate shallow-depth soils. When catchments were drying or dryer, atmospheric nitrate was completely consumed by biological processing as flowpaths shifted from lateral to vertical transport through soils. The source areas of unprocessed atmospheric nitrate were usually limited to soils that were adjacent to streams, with little to no near-surface saturation and transport of unprocessed nitrate from more distal hillslope positions. The occasional large amounts of unprocessed atmospheric nitrate in soil water

  15. Genetic basis for nitrate resistance in Desulfovibrio strains

    Directory of Open Access Journals (Sweden)

    Hannah eKorte

    2014-04-01

    Full Text Available Nitrate is an inhibitor of sulfate-reducing bacteria (SRB. In petroleum production sites, amendments of nitrate and nitrite are used to prevent SRB production of sulfide that causes souring of oil wells. A better understanding of nitrate stress responses in the model SRB, Desulfovibrio vulgaris Hildenborough and Desulfovibrio alaskensis G20, will strengthen predictions of environmental outcomes. Nitrate inhibition of SRB has historically been considered to result from the generation of small amounts of nitrite, to which SRB are quite sensitive. Here we explored the possibility that nitrate might inhibit SRB by a mechanism other than through nitrite inhibition. We found that nitrate-stressed D. vulgaris cultures grown in lactate-sulfate conditions eventually grew in the presence of high concentrations of nitrate, and their resistance continued through several subcultures. Nitrate consumption was not detected over the course of the experiment, suggesting adaptation to nitrate. With high-throughput genetic approaches employing TnLE-seq for D. vulgaris and a pooled mutant library of D. alaskensis, we determined the fitness of many transposon mutants of both organisms in nitrate stress conditions. We found that several mutants, including homologs present in both strains, had a greatly increased ability to grow in the presence of nitrate but not nitrite. The mutated genes conferring nitrate resistance included the gene encoding the putative Rex transcriptional regulator (DVU0916/Dde_2702, as well as a cluster of genes (DVU0251-DVU0245/Dde_0597-Dde_0605 that is poorly annotated. Follow-up studies with individual D. vulgaris transposon and deletion mutants confirmed high-throughput results. We conclude that, in D. vulgaris and D. alaskensis, nitrate resistance in wild-type cultures is likely conferred by spontaneous mutations. Furthermore, the mechanisms that confer nitrate resistance may be different from those that confer nitrite resistance.

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

    Science.gov (United States)

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

    2016-02-01

    A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. Radiation chemistry of the aqueous aluminium nitrate solution (Preprint no. RC-26)

    International Nuclear Information System (INIS)

    Kalkar, C.D.; Date, D.B.

    1991-01-01

    Radiolysis of aqueous aluminium nitrate solution is studied as a function of concentration in the range 10 -4 M to 10 -1 M. The stable radiolytic product of nitrate radiolysis is nitrite. The yield of nitrite linearly increases with absorbed dose. The G(NO 2 ) values are determined at various concentrations of aluminium nitrate. A suitable mechanism is proposed to explain the observed G-value for the reduction of nitrate to nitrite. (author). 6 refs., 1 tab

  18. Nitrate Measurment in Water Source of Karaj City and Zonning it Geographic Information Systems (GIS)

    OpenAIRE

    A.R. Shakib; J. Rahimi; M. Noori Sepehr; M. Zarrabi

    2015-01-01

    Background & Objectives: Nitrate is one of drinking water pollutant which is introduced to water body from municipal wastewater. Information on nitrate concentration and its distribution in water resource is necessary in safe drinking water supply. For that reason, the present work was done for investigation of nitrate in Karaj water supply resource and its zonning with Geographic Information Systems (GIS). Materials and Methods: In this work, the nitrate concentration in 200 wells of Karaj w...

  19. Nitrate Adsorption on Clay Kaolin: Batch Tests

    Directory of Open Access Journals (Sweden)

    Morteza Mohsenipour

    2015-01-01

    Full Text Available Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

  20. Photocatalytic Degradation of Malachite Green Using Nano-sized cerium-iron Oxide

    Directory of Open Access Journals (Sweden)

    K. L. Ameta

    2014-05-01

    Full Text Available Nano-sized cerium-iron oxide nanoparticles has been synthesized, characterized and explored as an efficient photocatalyst for the photocatalytic degradation of malachite green. The effects of different variables on degradation of dye were optimized such as the pH of the dye solution, dye concentration, amount of photocatalyst and light intensity. About 91% degradation of dye of 2×10-5 M concentration was observed after 2 hours at 8.5 pH and 600 Wm-2 light intensity. The reason for the high catalytic activity of the synthesized nanoparticles is ascribed to the high surface area which determines the active sites of the catalyst and accelerates the photocatalytic degradation.

  1. Boric Acid as an Accelerator of Cerium Surface Treatment on Aluminum

    Directory of Open Access Journals (Sweden)

    K. Cruz-Hernández

    2014-01-01

    Full Text Available Aluminum pieces are often used in various industrial processes like automotive and aerospace manufacturing, as well as in ornamental applications, so it is necessary to develop processes to protect these materials, processes that can be industrialized to protect the aluminum as well or better than chromate treatments. The purpose of this research is to evaluate boric acid as an accelerator by optimizing its concentration in cerium conversion coatings (CeCC with 10-minute immersion time with a concentration of 0.1 g L−1 over aluminum to protect it. The evaluation will be carried out by measuring anticorrosion properties with electrochemical techniques (polarization resistance, Rp, polarization curves, PC, and electrochemical impedance spectroscopy, EIS in NaCl 3.5% wt. aqueous solution and surface characterization with scanning electron microscopy (SEM.

  2. Properties of a epoxy-based powder coating containing modified montmorillonite with cerium

    International Nuclear Information System (INIS)

    Beux, A.R.D.; Piazza, D.; Zattera, A.J.; Ferreira, C.A.; Scienza, L.C.

    2014-01-01

    Organic coatings are widely used to prevent corrosion in metal structures. The incorporation of nanofiller the polymer matrix in order to obtain polymer nanocomposites has been arousing scientific and technological interest, because it provides significant improvements when incorporated into pure polymeric materials or conventional composites. In the present study were been developed epoxy-based powder coating with addition of different concentrations (2, 4 and 8% (w / w)) of the montmorillonite type Cloisite® 15A modified with cerium in the melt state on a double-screw extruder co-rotating. The coatings were characterized by average particle size, time (gel time) gel, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Coatings with intercalated structure was observed in the XRD analysis and confirmed by SEM to the observe an increase in the concentration of tactoids an increased filler content. (author)

  3. The UK Nitrate Time Bomb (Invited)

    Science.gov (United States)

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

    2013-12-01

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

  4. Thermochemical nitrate reduction

    International Nuclear Information System (INIS)

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

    1992-09-01

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

  5. Method of processing nitrate-containing radioactive liquid wastes

    International Nuclear Information System (INIS)

    Ogawa, Norito; Nagase, Kiyoharu; Otsuka, Katsuyuki; Ouchi, Jin.

    1983-01-01

    Purpose: To efficiently concentrate nitrate-containing low level radioactive liquid wastes by electrolytically dialyzing radioactive liquid wastes to decompose the nitrate salt by using an electrolytic cell comprising three chambers having ion exchange membranes and anodes made of special materials. Method: Nitrate-containing low level radioactive liquid wastes are supplied to and electrolytically dialyzed in a central chamber of an electrolytic cell comprising three chambers having cationic exchange membranes and anionic exchange membranes made of flouro-polymer as partition membranes, whereby the nitrate is decomposed to form nitric acid in the anode chamber and alkali hydroxide compound or ammonium hydroxide in the cathode chamber, as well as concentrate the radioactive substance in the central chamber. Coated metals of at least one type of platinum metal is used as the anode for the electrolytic cell. This enables efficient industrial concentration of nitrate-containing low level radioactive liquid wastes. (Yoshihara, H.)

  6. Extraction with tributyl phosphate (TBP) from ferric nitrate solutions

    International Nuclear Information System (INIS)

    Kolarik, Z.; Grudpan, K.

    1985-01-01

    Ferric nitrate acts as a strong salting-out agent in the extraction of thorium(IV), uranyl, europium(III), samarium(III) and zirconium(IV) nitrates as well as of nitric acid with tributyl phosphate in dodecane. Nitric acid, if present in the extraction system together with large amounts of ferric nitrate, markedly suppresses the extraction of thorium(IV) and lanthanides(III) but significantly supports the extraction of zirconium(IV). Separation factors of different metal pairs are presented as functions of the concentrations of ferric nitrate and nitric acid

  7. Thioploca spp: filamentous sulfur bacteria with nitrate vacuoles

    DEFF Research Database (Denmark)

    Jørgensen, BB; Gallardo, VA

    1999-01-01

    communities of large Thioploca species live along the Pacific coast of South America and in other upwelling areas of high organic matter sedimentation with bottom waters poor in oxygen and rich in nitrate. Each cell of these thioplocas harbors a large liquid vacuole which is used as a storage for nitrate...... with a concentration of lip to 506 mM. The nitrate is used as an electron acceptor for sulfide oxidation and the bacteria may grow autotrophically or mixotrophically using acetate or other organic molecules as carbon source. The filaments stretch up into the overlying seawater, from which they take up nitrate...

  8. Aluminum nitrate recrystallization and recovery from liquid extraction raffinates

    International Nuclear Information System (INIS)

    Griffith, W.L.; Compere, A.L.; Googin, J.M.; Huxtable, W.P.

    1991-09-01

    The solid sludges resulting form biodenitrification of discarded aluminum nitrate are the largest Y-12 Plant process solid waste. Aluminum nitrate feedstocks also represent a major plant materials cost. The chemical constraints on aluminum nitrate recycle were investigated to determine the feasibility of increasing recycle while maintaining acceptable aluminum nitrate purity. Reported phase behavior of analogous systems, together with bench research, indicated that it would be possible to raise the recycle rate from 35% to between 70 and 90% by successive concentration and recrystallization of the mother liquor. A full scale pilot test successfully confirmed the ability to obtain 70% recycle in existing process equipment

  9. Nitrate-nitrogen removal with small-scale reverse osmosis ...

    African Journals Online (AJOL)

    The nitrate-nitrogen concentration in water supplied to clinics in Limpopo Province is too high to be fit for human consumption (35 to 75 mg/ℓ NO3-N). Therefore, small-scale technologies (reverse osmosis, ion-exchange and electrodialysis) were evaluated for nitrate-nitrogen removal to make the water potable (< 10 mg/ℓ ...

  10. Relationship of stand age to streamwater nitrate in New Hampshire

    Science.gov (United States)

    William B. Leak; C. Wayne Martin

    1975-01-01

    Streamwater nitrate content of six watersheds during spring and summer was apparently related to stand age or age since disturbance. Nitrate concentration averaged 10.3 ppm right after cutting, dropped to a trace in medium-aged stands, and then rose again to a maximum of 4.8 ppm as stands became overmature.

  11. Method for improved decomposition of metal nitrate solutions

    Science.gov (United States)

    Haas, Paul A.; Stines, William B.

    1983-10-11

    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.

  12. Critical indices for reversible gamma-alpha phase transformation in metallic cerium

    Science.gov (United States)

    Soldatova, E. D.; Tkachenko, T. B.

    1980-08-01

    Critical indices for cerium have been determined within the framework of the pseudobinary solution theory along the phase equilibrium curve, the critical isotherm, and the critical isobar. The results obtained verify the validity of relationships proposed by Rushbrook (1963), Griffiths (1965), and Coopersmith (1968). It is concluded that reversible gamma-alpha transformation in metallic cerium is a critical-type transformation, and cerium has a critical point on the phase diagram similar to the critical point of the liquid-vapor system.

  13. The effect of cerium valence states at cerium oxide nanoparticle surfaces on cell proliferation

    KAUST Repository

    Naganuma, Tamaki

    2014-05-01

    Understanding and controlling cell proliferation on biomaterial surfaces is critical for scaffold/artificial-niche design in tissue engineering. The mechanism by which underlying integrin ligates with functionalized biomaterials to induce cell proliferation is still not completely understood. In this study, poly-l-lactide (PL) scaffold surfaces were functionalized using layers of cerium oxide nanoparticles (CNPs), which have recently attracted attention for use in therapeutic application due to their catalytic ability of Ce4+ and Ce3+ sites. To isolate the influence of Ce valance states of CNPs on cell proliferation, human mesenchymal stem cells (hMSCs) and osteoblast-like cells (MG63) were cultured on the PL/CNP surfaces with dominant Ce4+ and Ce3+ regions. Despite cell type (hMSCs and MG63 cells), different surface features of Ce4+ and Ce3+ regions clearly promoted and inhibited cell spreading, migration and adhesion behavior, resulting in rapid and slow cell proliferation, respectively. Cell proliferation results of various modified CNPs with different surface charge and hydrophobicity/hydrophilicity, indicate that Ce valence states closely correlated with the specific cell morphologies and cell-material interactions that trigger cell proliferation. This finding suggests that the cell-material interactions, which influence cell proliferation, may be controlled by introduction of metal elements with different valence states onto the biomaterial surface. © 2014 Elsevier Ltd.

  14. Trend Analyses of Nitrate in Danish Groundwater

    DEFF Research Database (Denmark)

    Hansen, B.; Thorling, L.; Dalgaard, Tommy

    2012-01-01

    This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......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...

  15. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaodong, E-mail: xzhang39@utk.edu [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Hayward, Jason P. [Department of Nuclear Engineering, University of Tennessee, TN 37996 (United States); Oak Ridge National Lab, Oak Ridge, TN 37831 (United States)

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick’s second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  16. Effect of adduct formation on valent state of cerium in its. beta. -diketonates

    Energy Technology Data Exchange (ETDEWEB)

    Spitsyn, V.I.; Martynenko, L.I.; Pechurova, N.I.; Snezhko, N.I.; Murav' eva, I.A.; Anufrieva, S.I. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1982-04-01

    Physicochemical investigation of the system cerium (III, IV)-..beta..-diketone-additional ligand shows that ..beta..-diketonate ability to adduct formation decreases in the series tenoyltrifluoro-acetonate > acetylacetonate > dibenzoylmethanate > benzoylmethanate. Adduct formation of the cerium (III, IV) ..beta..-diketonates stabilizes cerium in trivalent condition, while oxidation degree 4+ is stable in tetrakis-..beta..-diketonates. The additional ligands are arranged in the series: tributhylphosphate < trioctyl-phosphineoxide < triphenylphosphineoxide < ..cap alpha.., ..cap alpha..'-dipyridyl < o-phenanthroline by the effect on cerium (III) stabilization in its ..beta..-diketonates.

  17. Effect of adduct formation on valent state of cerium in its ν-diketonates

    International Nuclear Information System (INIS)

    Spitsyn, V.I.; Martynenko, L.I.; Pechurova, N.I.; Snezhko, N.I.; Murav'eva, I.A.; Anufrieva, S.I.

    1982-01-01

    Physicochemical investigation of the system cerium (III, IV)-ν-diketone-additional ligand shows that ν-diketonate ability to adduct formation decreases in the series tenoyltrifluoro-acetonate > acetylacetonate > dibenzoylmethanate > benzoylmethanate. Adduct formation of the cerium (III, IV) ν-diketonates stabilizes cerium in trivalent condition, while oxidation degree 4+ is stable in tetrakis-ν-diketonates. The additional ligands are arranged in the series: tributhylphosphate < trioctyl-phosphineoxide < triphenylphosphineoxide < α, α'-dipyridyl < o-phenanthroline by the effect on cerium (III) stabilization in its ν-diketonates

  18. Study of cerium diffusion in undoped lithium-6 enriched glass with Rutherford backscattering spectrometry

    Science.gov (United States)

    Zhang, Xiaodong; Moore, Michael E.; Lee, Kyung-Min; Lukosi, Eric D.; Hayward, Jason P.

    2016-07-01

    Undoped lithium-6 enriched glasses coated with pure cerium (99.9%) with a gold protection layer on top were heated at three different temperatures (500, 550, and 600 °C) for varied durations (1, 2, and 4 h). Diffusion profiles of cerium in such glasses were obtained with the conventional Rutherford backscattering technique. Through fitting the diffusion profiles with the thin-film solution of Fick's second law, diffusion coefficients of cerium with different annealing temperatures and durations were solved. Then, the activation energy of cerium for the diffusion process in the studied glasses was found to be 114 kJ/mol with the Arrhenius equation.

  19. Identification of nitrate sources and discharge-depending nitrate dynamics in a mesoscale catchment

    Science.gov (United States)

    Mueller, Christin; Strachauer, Ulrike; Brauns, Mario; Musolff, Andreas; Kunz, Julia Vanessa; Brase, Lisa; Tarasova, Larisa; Merz, Ralf; Knöller, Kay

    2017-04-01

    During the last decades, nitrate concentrations in surface and groundwater have increased due to land use change and accompanying application of fertilizer in agriculture as well as increased atmospheric deposition. To mitigate nutrient impacts on downstream aquatic ecosystems, it is important to quantify potential nitrate sources, instream nitrate processing and its controls in a river system. The objective of this project is to characterize and quantify (regional) scale dynamics and trends in water and nitrogen fluxes of the entire Holtemme river catchment in central Germany making use of isotopic fingerprinting methods. Here we compare two key date sampling campaigns in 2014 and 2015, with spatially highly resolved measurements of discharge at 23 sampling locations including 11 major tributaries and 12 locations at the main river. Additionally, we have data from continuous runoff measurements at 10 locations operated by the local water authorities. Two waste water treatment plants contribute nitrogen to the Holtemme stream. This contribution impacts nitrate loads and nitrate isotopic signatures depending on the prevailing hydrological conditions. Nitrogen isotopic signatures in the catchment are mainly controlled by different sources (nitrified soil nitrogen in the headwater and manure/ effluents from WWTPs in the lowlands) and increase with raising nitrate concentrations along the main river. Nitrate loads at the outlet of the catchment are extremely different between both sampling campaigns (2014: NO3- = 97 t a-1, 2015: NO3- = 5 t a-1) which is associated with various runoff (2014: 0.8 m3 s-1, 2015: 0.2 m3 s-1). In 2015, the inflow from WWTP's raises the NO3- loads and enriches δ18O-NO3 values. Generally, oxygen isotope signatures from nitrate are more variable and are controlled by biogeochemical processes in concert with the oxygen isotopic composition of the ambient water. Elevated δ18O-NO3 in 2015 are most likely due to higher temperatures and lower

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

    Science.gov (United States)

    2015-01-01

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

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

    Science.gov (United States)

    Daiber, Andreas; Münzel, Thomas

    2015-10-10

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

  2. Complex formation of transferrin with tetravalent plutonium and cerium

    International Nuclear Information System (INIS)

    Subramanian, M.S.; Oomen, I.K.

    1981-01-01

    Gel filtration experiments with 239 Pu labelled In Vitro bovine serum showed that the metal ion is bound to the transferrin of the serum proteins as in the case of iron labelled serum. This was confirmed by polyacrylamide gel electrophoresis. The ovotransferrin prepared from chicken egg white which was devoid of hemopexin contaminant was found to complex both tetravalent plutonium and cerium giving visible absorption peak at 365 and 435 nm respectively. The binding capacity of ovotransferrin with tetravalent plutonium and cerium, determined by spectrophotometric titration indicates that two metal ions are bound to each protein molecule as in the case of iron. The average molecular weight computed from this binding capacity measurements was found to be 71,000-75,000. The number of protons liberated for each metal ion bound was found to be three as in the case of iron. (author)

  3. Charge transfer cross sections for dysprosium and cerium

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Hajime; Tamura, Koji; Okazaki, Tetsuji; Shibata, Takemasa [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-06-01

    Symmetric resonant charge transfer cross sections between singly ionized ions and the parent atoms were measured for dysprosium and cerium in the impact energy of 200-2000eV. The cross sections were determined from the ratio between the number of ions produced by charge transfer and those in primary ion beam. The primary ion beam was produced by a laser ion source in which their atoms were ionized by laser resonant photo-ionization. The slow ions produced by charge transfer and fast primary ions were detected with Faraday cups. The obtained cross sections were (1.82{+-}0.14) x 10{sup -14} cm{sup 2} for dysprosium and (0.88{+-}0.12) x 10{sup -14} cm{sup 2} for cerium in the above energy range. The difference of these values can mostly be explained by considering the electron configurations of these atoms and ions. (author)

  4. Charge transfer cross sections for dysprosium and cerium

    International Nuclear Information System (INIS)

    Adachi, Hajime; Tamura, Koji; Okazaki, Tetsuji; Shibata, Takemasa

    1998-06-01

    Symmetric resonant charge transfer cross sections between singly ionized ions and the parent atoms were measured for dysprosium and cerium in the impact energy of 200-2000eV. The cross sections were determined from the ratio between the number of ions produced by charge transfer and those in primary ion beam. The primary ion beam was produced by a laser ion source in which their atoms were ionized by laser resonant photo-ionization. The slow ions produced by charge transfer and fast primary ions were detected with Faraday cups. The obtained cross sections were (1.82±0.14) x 10 -14 cm 2 for dysprosium and (0.88±0.12) x 10 -14 cm 2 for cerium in the above energy range. The difference of these values can mostly be explained by considering the electron configurations of these atoms and ions. (author)

  5. Spatial assessment of animal manure spreading and groundwater nitrate pollution

    Directory of Open Access Journals (Sweden)

    Roberta Infascelli

    2009-11-01

    Full Text Available Nitrate concentration in groundwater has frequently been linked to non-point pollution. At the same time the existence of intensive agriculture and extremely intensive livestock activity increases the potential for nitrate pollution in shallow groundwater. Nitrate used in agriculture could cause adverse effects on human and animal health. In order to evaluate the groundwater nitrate pollution, and how it might evolve in time, it is essential to develop control systems and to improve policies and incentives aimed at controlling the amount of nitrate entering downstream water systems. The province of Caserta in southern Italy is characterized by high levels of animal manure loading. A comparison between manure nitrogen production and nitrate concentration in groundwater was carried out in this area, using geostatistical tools and spatial statistics. The results show a discrepancy between modelling of nitrate leaching and monitoring of the groundwater and, moreover, no spatial correlation between nitrogen production in livestock farms and nitrate concentration in groundwater, suggesting that producers are not following the regulatory procedures for the agronomic use of manure. The methodology developed in this paper could be applied also in other regions in which European Union fertilization plans are not adequately followed.

  6. Light-induced protein nitration and degradation with HONO emission

    Science.gov (United States)

    Meusel, Hannah; Elshorbany, Yasin; Kuhn, Uwe; Bartels-Rausch, Thorsten; Reinmuth-Selzle, Kathrin; Kampf, Christopher J.; Li, Guo; Wang, Xiaoxiang; Lelieveld, Jos; Pöschl, Ulrich; Hoffmann, Thorsten; Su, Hang; Ammann, Markus; Cheng, Yafang

    2017-10-01

    Proteins can be nitrated by air pollutants (NO2), enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO) from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM). Bovine serum albumin (BSA) and ovalbumin (OVA) were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS/UV illuminated conditions, while simultaneous decomposition of (nitrated) proteins was also found during long-term (20 h) irradiation exposure. Measurements of gas exchange on TNM-nitrated proteins revealed that HONO can be formed and released even without contribution of instantaneous heterogeneous NO2 conversion. NO2 exposure was found to increase HONO emissions substantially. In particular, a strong dependence of HONO emissions on light intensity, relative humidity, NO2 concentrations and the applied coating thickness was found. The 20 h long-term studies revealed sustained HONO formation, even when concentrations of the intact (nitrated) proteins were too low to be detected after the gas exchange measurements. A reaction mechanism for the NO2 conversion based on the Langmuir-Hinshelwood kinetics is proposed.

  7. Use of tensiometer for in situ measurement of nitrate leaching

    Energy Technology Data Exchange (ETDEWEB)

    Li, K.; Reddy, M.R.

    1999-07-01

    In order to monitor nitrate leaching from non-point source pollution, this study used tensiometers to measure in situ nitrate concentration and soil-moisture potential. Instead of filling the tensiometers with pure water, the study filled the tensiometers with nitrate ionic strength adjuster (ISA, 1 M (NH{sub 4}){sub 2}SO{sub 4}). After the installation of the tensiometers at various depths along soil profiles, a portable pressure transducer was used to measure the soil moisture potential, and a nitrate electrode attached to an ion analyzer was used to measure the nitrate concentration in situ. The measurement was continuous and non-destructive. To test this method in the laboratory, eight bottles filled with pure sand were treated with known nitrate solutions, and a tensiometer was placed in each bottle. Measurements were taken every day for 30 days. Laboratory test showed a linear relationship between the known nitrate concentration and the tensiometer readings (R{sup 2} = 0.9990). Then a field test was conducted in a watermelon field with green manure mulch. Field data indicated a potential of nitrate leaching below the soil depth of 100 cm when crop uptake of nutrients was low.

  8. Far infrared properties of PbTe doped with cerium

    International Nuclear Information System (INIS)

    Nikolic, P.M.; Koenig, W.; Vujatovic, S.S.; Blagojevic, V.; Lukovic, D.; Savic, S.; Radulovic, K.; Urosevic, D.; Nikolic, M.V.

    2007-01-01

    Single crystal samples of lead telluride doped with cerium were made using the Bridgman method. Far infrared reflectivity spectra in the temperature range from 10 to 300 K are presented. The experimental data were numerically analyzed using a fitting procedure based on the plasmon-phonon interaction model and optical parameters were determined. Two additional local modes were observed at about 138 and 337 cm -1 . The origin of these local vibrational impurity modes was discussed

  9. Far infrared properties of PbTe doped with cerium

    Energy Technology Data Exchange (ETDEWEB)

    Nikolic, P.M. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia)]. E-mail: nikolic@sanu.ac.yu; Koenig, W. [Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 7000 Stuttgart 80 (Germany); Vujatovic, S.S. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Blagojevic, V. [Faculty of Electronic Engineering, University of Belgrade, Bulevar Kralja Aleksandra 73, 11000 Belgrade (Serbia); Lukovic, D. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Savic, S. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Radulovic, K. [Institute of Technical Sciences SASA, Knez Mihailova 35/IV, 11000 Belgrade (Serbia); Urosevic, D. [Mathematical Institute SASA, Knez Mihailova 35/I, 11000 Belgrade (Serbia); Nikolic, M.V. [Center for Multidisciplinary Studies of the University of Belgrade, Kneza Viseslava 1, Belgrade (Serbia)

    2007-05-16

    Single crystal samples of lead telluride doped with cerium were made using the Bridgman method. Far infrared reflectivity spectra in the temperature range from 10 to 300 K are presented. The experimental data were numerically analyzed using a fitting procedure based on the plasmon-phonon interaction model and optical parameters were determined. Two additional local modes were observed at about 138 and 337 cm{sup -1}. The origin of these local vibrational impurity modes was discussed.

  10. Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode

    Energy Technology Data Exchange (ETDEWEB)

    Can, Faruk; Korkut Ozoner, Seyda; Ergenekon, Pinar; Erhan, Elif, E-mail: e.erhan@gyte.edu.tr

    2012-01-01

    This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44-1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N = 3) with a relative standard deviation (RSD) of 5.4% (n = 7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 {mu}g/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday. - Highlights: Black-Right-Pointing-Pointer K{sub 3}Fe(CN){sub 6} has been used for the first time as mediator for nitrate reductase. Black-Right-Pointing-Pointer Better performance was obtained in comparison to other nitrate biosensor studies operated with various mediators. Black-Right-Pointing-Pointer Analytical parameters were better than standard nitrate analysis methods.

  11. Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode

    International Nuclear Information System (INIS)

    Can, Faruk; Korkut Ozoner, Seyda; Ergenekon, Pinar; Erhan, Elif

    2012-01-01

    This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44–1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N = 3) with a relative standard deviation (RSD) of 5.4% (n = 7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 μg/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday. - Highlights: ► K 3 Fe(CN) 6 has been used for the first time as mediator for nitrate reductase. ► Better performance was obtained in comparison to other nitrate biosensor studies operated with various mediators. ► Analytical parameters were better than standard nitrate analysis methods.

  12. Jet formation in cerium metal to examine material strength

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, B. J., E-mail: bjjensen@lanl.gov; Cherne, F. J.; Prime, M. B.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Fezzaa, K. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Iverson, A. J.; Carlson, C. A. [National Security Technologies LLC, Los Alamos, New Mexico 87544 (United States)

    2015-11-21

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  13. Dielectric studies on cerium doped BaLa2Ti3O10

    Directory of Open Access Journals (Sweden)

    Parshuram B. Abhange

    2015-12-01

    Full Text Available The BaLa2-xCexTi3O10 samples (with x = 0.2, 0.4, 0.6 and 0.8 were prepared by hydroxide co-precipitation method and finally sintered at 1150 °C. The structure of the prepared samples was characterized by XRD and SEM. The single phase material was confirmed only for the BaLa1.8Ce0.2Ti3O10 ceramics. However, at higher cerium concentration secondary phase was observed. The characteristic plate-like structure, having grains with submicrometer thickness and high aspect ratio, was clearly observed by SEM. The results of dielectric measurement suggest that the appropriate adjustment of doping (with x between 0.2 and 0.8 will give sufficient high dielectric constant at very low loss. The resistivity of samples decreases with increase in temperature indicating the normal semiconducting electrical behaviour.

  14. Cerium and cobalt movement with litter leachate in a forest soil

    International Nuclear Information System (INIS)

    Thomas, W.A.

    1975-01-01

    Leachate containing 144 Ce and 60 Co from leaf litter of mockernut hickory (Carya tomentosa Nutt.) and black gum (Nyssa sylvatica Marsh.) trees was applied to a forest soil in three different treatments to estimate the rates at which these elements move downward after release in the litter layer: (a) single application, (b) single application at twice the concentration in (a), and (c) four periodic applications over 1 year. Regression b values describing the distribution of 144 Ce and 60 Co 4 years after the first applications did not differ significantly (P greater than 0.01) among treatments for either element, but movement by 144 Ce significantly exceeded that by 60 Co for all treatments. A combination of chemical and physical phenomena retained cerium and cobalt in the biologically active zones of soil, with the organic layer and upper 3 cm of mineral soil accounting for 68 percent of the 144 Ce and 91 percent of the 60 Co

  15. Separation of pure Cerium oxides from rare earth compounds. Homogeneous precipitation using Urea-Hydrogen Peroxide

    International Nuclear Information System (INIS)

    Umeda, K.; Abrao, E.

    1975-01-01

    The obtainment of ceric oxide (CeO 2 ) of purity higher than 97% by application of homogeneous precipitation technique is described. The selective separation of cerium was reached by hydrolysis of urea in the presence of hydrogen peroxide, using a rare earths concentrate named rare earths chloride, a natural mixture of all lanthanides provenient from the industrialization of monazite. The best conditions for the preparation of CeO 2 of 94% purity are: 35-70g R 2 O 3 /1 and pH2,0 hydrolysis temperature: 88-90 0 C, urea/R 2 O 3 ratio: 4, H 2 O 2 /Ce 2 O 3 ratio: 1,5-5,0 and hydrolysis duration: 4 hours. A leaching procedure of the precipitate with 0,25-0,75M NHO 3 leads to a product of 97-99,5% CeO 2

  16. Chaos control in the cerium-catalyzed Belousov–Zhabotinsky reaction using recurrence quantification analysis measures

    International Nuclear Information System (INIS)

    Fatoorehchi, Hooman; Zarghami, Reza; Abolghasemi, Hossein; Rach, Randolph

    2015-01-01

    Highlights: •Theoretical and experimental chaos control for the Belousov–Zhabotinsky-CSTR system. •Application of recurrence analysis quantification for chaos control by feedback loops. •Optimization of determinism and recurrence rate as RQA-based measures. •Accurate solution of the Montanator model by the multi-stage Adomian decomposition method. -- Abstract: Chaos control in the Belousov–Zhabotinsky-CSTR system was investigated theoretically and experimentally by reconstructing the phase space of the cerium (IV) ions concentration time series and then optimizing recurrence quantification analysis measures. The devised feedback loop acting on the reactor inlet flow rate was able to experimentally suppress chaos and drive the system to an almost predictable state with approximately 93% determinism. Similar theoretical results have also been demonstrated in numerical simulations using the four-variable Montanator model as solved by the multistage Adomian decomposition method

  17. Nitrate retention in a sand plains stream and the importance of groundwater discharge

    Science.gov (United States)

    Robert S. Stelzer; Damion R. Drover; Susan L. Eggert; Maureen A. Muldoon

    2011-01-01

    We measured net nitrate retention by mass balance in a 700-m upwelling reach of a third-order sand plains stream, Emmons Creek, from January 2007 to November 2008. Surface water and ground-water fluxes of nitrate were determined from continuous records of discharge and from nitrate concentrations based on weekly and biweekly sampling at three surface water stations and...

  18. Reactivity of Metal Nitrates.

    Science.gov (United States)

    1982-07-20

    02NOCuOH Any mechanism suggested for the nitration of aromatic systems by titanium(IV) nitrate must take into account the observed similarity, in...occurs. -26- References 1. For recent reviews see (a) R. B. Moodie and K. Schofield, Accounts Chem. Res., 1976, 9, 287; (b) G. A. Olah and S. J. Kuhn...Ithaca, N.Y., 1969, Chapter VI; L. M. Stock, Prog. Phys. Org. Chem., 1976, 12, 21; J. G. Hoggett , R. B. Moodie, J. R. Penton, and K. Schofield

  19. Separation and recovery of sodium nitrate from low-level radioactive liquid waste by electrodialysis

    International Nuclear Information System (INIS)

    Meguro, Yoshihiro; Kato, Atsushi; Watanabe, Yoko; Takahashi, Kuniaki

    2011-01-01

    An advanced method, in which electrodialysis separation of sodium nitrate and decomposition of nitrate ion are combined, has been developed to remove nitrate ion from low-level radioactive liquid wastes including nitrate salts of high concentration. In the electrodialysis separation, the sodium nitrate was recovered as nitric acid and sodium hydroxide. When they are reused, it is necessary to reduce the quantity of impurities getting mixed with them from the waste fluid as much as possible. In this study, therefore, a cation exchange membrane with permselectivity for sodium ion and an anion exchange membrane with permselectivity for monovalent anion were employed. Using these membranes sodium and nitrate ions were effectively removed form a sodium nitrate solution of high concentration. And also it was confirmed that sodium ion was successfully separated from cesium and strontium ions and that nitrate ion was separated from sulfate and phosphate ions. (author)

  20. Impact of ammonium nitrate and sodium nitrate on tadpoles of Alytes obstetricans.

    Science.gov (United States)

    Garriga, Núria; Montori, A; Llorente, G A

    2017-07-01

    The presence of pesticides, herbicides and fertilisers negatively affect aquatic communities in general, and particularly amphibians in their larval phase, even though sensitivity to pollutants is highly variable among species. The Llobregat Delta (Barcelona, Spain) has experienced a decline of amphibian populations, possibly related to the reduction in water quality due to the high levels of farming activity, but also to habitat loss and alteration. We studied the effects of increasing ammonium nitrate and sodium nitrate levels on the survival and growth rate of Alytes obstetricans tadpoles under experimental conditions. We exposed larvae to increasing concentrations of nitrate and ammonium for 14 days and then exposed them to water without pollutants for a further 14 days. Only the higher concentrations of ammonium (>33.75 mg/L) caused larval mortality. The growth rate of larvae was reduced at ≥22.5 mg/L NH 4 + , although individuals recovered and even increased their growth rate once exposure to the pollutant ended. The effect of nitrate on growth rate was detected at ≥80 mg/L concentrations, and the growth rate reduction in tadpoles was even observed during the post-exposure phase. The concentrations of ammonium with adverse effects on larvae are within the range levels found in the study area, while the nitrate concentrations with some adverse effect are close to the upper range limit of current concentrations in the study area. Therefore, only the presence of ammonium in the study area is likely to be considered of concern for the population of this species, even though the presence of nitrate could cause some sublethal effects. These negative effects could have an impact on population dynamics, which in this species is highly sensitive to larval mortality due to its small clutch size and prolonged larval period compared to other anuran amphibians.

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

    Science.gov (United States)

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

    2015-10-01

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

  2. The developments and challenges of cerium half-cell in zinc–cerium redox flow battery for energy storage

    International Nuclear Information System (INIS)

    Xie, Zhipeng; Liu, Qingchao; Chang, Zhiwen; Zhang, Xinbo

    2013-01-01

    Zinc–cerium redox flow batteries (ZCBs) are emerging as a very promising new technology with the potential to store a large amount of energy economically and efficiently, thanking to its highest thermodynamic open-circuit cell voltage among all the currently studied aqueous redox flow batteries. However, there are numerous scientific and technical challenges that must be overcome if this alluring promise is to turn into reality, from designing the battery structure, to optimizing the electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. This review article is the first summary of the most significant developments and challenges of cerium half-cell and the current understanding of their chemistry. We are certain that this review will be of great interest to audience over a broad range, especially in fields of energy storage, electrochemistry, and chemical engineering

  3. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    International Nuclear Information System (INIS)

    Tam, Phuong Dinh; Thang, Cao Xuan

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO 2 nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO 2 nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) 6 ] 3−/4− as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL −1 . Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. • The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL −1 .

  4. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: phuongdinhtam@gmail.com; Thang, Cao Xuan, E-mail: thang.caoxuan@hust.edu.vn

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO{sub 2} nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO{sub 2} nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) {sub 6}] {sup 3−/4−} as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL{sup −1}. Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. • The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL{sup −1}.

  5. [Can nitrates lead to indirect toxicity?].

    Science.gov (United States)

    Hamon, M

    2007-09-01

    For many years, nitrates have been used, at low dosages, as an additive in salted food. New laws have been promulgated to limit their concentration in water due to increased levels found in soils, rivers and even the aquifer. Although nitrate ions themselves have not toxic properties, bacterial reduction into nitrite ions (occurring even in aqueous medium) can lead to nitrous anhydride, which in turn generates nitrosonium ions. Nitrosium ions react with secondary amine to give nitrosamines, many of which are cancer-inducing agents at very low doses. Opinions on this toxicity are clear-cut and difficult to reconcile. In fact, increased levels are due, in a large part, to the use of nitrates as fertiliéers but also to bacterial transformation of human and animal nitrogenous wastes such as urea.

  6. Influence of nitric acid on the kinetic of complexation of uranyl nitrate extracted by TBP

    International Nuclear Information System (INIS)

    Pushlenkov, M.F.; Zimenkov, V.V.

    1982-02-01

    The effect of nitric acid on the solvatation rate of uranyl nitrate with tributyl phosphate is studied. In the process of mass transfer, it is shown that nitric acid enables the extraction of uranyl nitrate, therefore its concentration in the organic phase exceeds that in equilibrium solution. Subsequently uranyl nitrate ''displaces'' nitric acid. The presence of the acid in aqueous and organic phases affects in a complicated manner the rate of solvatation of uranyl nitrate with tributyl phosphate [fr

  7. Evaluation of Nitrate Transport in Clay Soil

    Directory of Open Access Journals (Sweden)

    Morteza Seyedian

    2016-09-01

    Full Text Available  Background and purpose: With the increase in world population and the need to provide food, farmers are now using a variety of chemical fertilizers, organic pesticides have turned. Indiscriminate use of these inputs without considering its side effects, both environmental problems and brings in terms of human health. Among these, organic fertilizers contain soluble compounds such as nitrate. These compounds through precipitation or irrigation of the soil solution, groundwater and surface water resources are. The purpose of this study was to determine the amount of nitrate transport in clay and simulation software using HYDRUS2D. Methods: In order to perform it, 5 different height of soil column 20, 40, 60, 80 and 100 cm selected. In thicknesses of 20, 40, 60 and 80 cm respectively output levels after a period of 6, 12, 18 and 22 hours to input the concentration of nitrate (50 mg/lit is. In thicknesses of 20, 40, 60 and 80 cm, respectively, after the time of 5/6, 5/12, 21, and 25-hour concentration of 50 mg/lit is output. In thickness 20, 40, 60 and 80cm, outlet concentration after 6, 12, 18 and 22 minutes inlet concentration (50mg/lit. Results: The result showed that Hydrus software ability of simulates nitrate movement in soil and result of Hydrus software and laboratory data near. Conclusions: With increasing soil thickness difference HYDRUS2D results and experimental data more and more time to transfer nitrate were spent with increasing thickness. 

  8. SU-E-T-279: Dose Enhancement Effect Due to Cerium Oxide Nanoparticles Employed as Radiation Protectants

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Z; Altundal, Y; Sajo, E [Univ Massachusetts Lowell, Lowell, MA (United States); Ngwa, W [Univ Massachusetts Lowell, Lowell, MA (United States); Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical, Boston, MA (United States)

    2015-06-15

    Purpose: The goal of radiotherapy is to maximize radiation dose to diseased cells while minimizing radiation damage to normal tissues. In order to minimize damage to normal tissues, cerium oxide nanoparticles (nanoceria) are currently considered as a radioprotectant. However, some studies have reported concerns that nanoceria can also lead to radiotherapy dose enhancement due to the high atomic number of cerium, especially when used in conjunction with kV energy and brachytherapy sources. In this study, this concern is investigated to determine if the concentrations of nanoceria employed in in-vivo studies to confer radioprotection can engender a significant dose enhancement. Methods: Radiation with energies ranging from 50kVp to 140kVp is investigated in this work along with brachytherapy sources Pd-103 and I-125. A previously established theoretical model is used to calculate the dose enhancement factor (DEF). In this model, each cell is assumed to be a voxel of size (10 µm, 10 µm, 10 µm) with nanoceria homogeneously distributed among them. Electron energy loss formula of Cole is used to calculate energy (and hence dose) deposited by photoelectrons and Auger electrons in each tissue voxel due to irradiation of nanoceria. The DEF is defined as the ratio of the dose with and without nanoparticles. Results: DEF calculation results are smaller than 1.02 with dosages of nanoceria smaller than 0.645 mg/g, which is shown to be sufficiently protective by some previous in-vitro and in-vivo experiments. The brachytherapy sources show higher DEF’s than kVp radiations. DEF peaks are consistent with K shell and L shell energies of cerium, 40 keV and 6 keV, respectively. Conclusion: The results show that for sufficiently radioprotective concentrations of nanoceria, there will be minimal DEF when used in conjunction with clinically applicable kV energy radiotherapy sources or brachytherapy sources.

  9. Chemical and structural analyses of subsurface crevices formed during spontaneous deposition of cerium-based conversion coatings

    Energy Technology Data Exchange (ETDEWEB)

    Heller, Daimon K, E-mail: dkheller@mmm.com; Fahrenholtz, William G., E-mail: billf@mst.edu; O' Keefe, Matthew J., E-mail: mjokeefe@mst.edu

    2011-11-15

    Subsurface crevices formed during the deposition of cerium-based conversion coatings were analyzed in cross-section to assess the effect of deposition and post-treatment on the structure and chemistry of phases present. An Al-O containing phase, believed to be amorphous Al(OH){sub 3}, was formed in crevices during coating deposition. Analysis by energy dispersive X-ray spectroscopy revealed the presence of up to 1.6 at.% chlorine within the Al-O phase, which was likely a product of soluble chlorides that were present in the coating solution. Cerium was not detected within crevices. After post-treatment in an 85 deg. C aqueous phosphate solution, the chloride concentration was reduced to {<=} 0.30 at.% and electron diffraction of the Al-O phase produced ring patterns, indicating it had crystallized. Some diffraction patterns could be indexed to gibbsite (Al(OH){sub 3}), but others are believed to be a combination of hydrated aluminum hydroxides and/or oxides. Aluminum phosphate was not identified. Separately from its effect on cerium-based conversion coatings, phosphate post-treatment improved the corrosion resistance of Al 2024-T3 substrates by acting to crystallize Al(OH){sub 3} present on interior surfaces of crevices and by reducing the chloride concentration in this phase. - Highlights: {yields} Analysis of subsurface crevices formed during deposition of Ce-based conversion coatings. {yields} Phosphate post-treatment improved corrosion protection in salt spray testing. {yields} Post-treatment affected the composition and structure of regions within crevices. {yields} Crystallized Al(OH){sub 3} within crevices acted as a more effective barrier to chloride ions.

  10. Distribution and Sources of Nitrate-Nitrogen in Kansas Groundwater

    Directory of Open Access Journals (Sweden)

    Margaret A. Townsend

    2001-01-01

    Full Text Available Kansas is primarily an agricultural state. Irrigation water and fertilizer use data show long- term increasing trends. Similarly, nitrate-N concentrations in groundwater show long-term increases and exceed the drinking-water standard of 10 mg/l in many areas. A statistical analysis of nitrate-N data collected for local and regional studies in Kansas from 1990 to 1998 (747 samples found significant relationships between nitrate-N concentration with depth, age, and geographic location of wells. Sources of nitrate-N have been identified for 297 water samples by using nitrogen stable isotopes. Of these samples, 48% showed fertilizer sources (+2 to +8 and 34% showed either animal waste sources (+10 to +15 with nitrate-N greater than 10 mg/l or indication that enrichment processes had occurred (+10 or above with variable nitrate-N or both. Ultimate sources for nitrate include nonpoint sources associated with past farming and fertilization practices, and point sources such as animal feed lots, septic systems, and commercial fertilizer storage units. Detection of nitrate from various sources in aquifers of different depths in geographically varied areas of the state indicates that nonpoint and point sources currently impact and will continue to impact groundwater under current land uses.

  11. Nitrate Leaching Management

    Science.gov (United States)

    Nitrate (NO3) leaching is a significant nitrogen (N) loss process for agriculture that must be managed to minimize NO3 enrichment of groundwater and surface waters. Managing NO3 leaching should involve the application of basic principles of understanding the site’s hydrologic cycle, avoiding excess ...

  12. Does the evidence about health risks associated with nitrate ingestion warrant an increase of the nitrate standard for drinking water?

    Science.gov (United States)

    van Grinsven, Hans JM; Ward, Mary H; Benjamin, Nigel; de Kok, Theo M

    2006-01-01

    Several authors have suggested that it is safe to raise the health standard for nitrate in drinking water, and save money on measures associated with nitrate pollution of drinking water resources. The major argument has been that the epidemiologic evidence for acute and chronic health effects related to drinking water nitrate at concentrations near the health standard is inconclusive. With respect to the chronic effects, the argument was motivated by the absence of evidence for adverse health effects related to ingestion of nitrate from dietary sources. An interdisciplinary discussion of these arguments led to three important observations. First, there have been only a few well-designed epidemiologic studies that evaluated ingestion of nitrate in drinking water and risk of specific cancers or adverse reproductive outcomes among potentially susceptible subgroups likely to have elevated endogenous nitrosation. Positive associations have been observed for some but not all health outcomes evaluated. Second, the epidemiologic studies of cancer do not support an association between ingestion of dietary nitrate (vegetables) and an increased risk of cancer, because intake of dietary nitrate is associated with intake of antioxidants and other beneficial phytochemicals. Third, 2–3 % of the population in Western Europe and the US could be exposed to nitrate levels in drinking water exceeding the WHO standard of 50 mg/l nitrate, particularly those living in rural areas. The health losses due to this exposure cannot be estimated. Therefore, we conclude that it is not possible to weigh the costs and benefits from changing the nitrate standard for drinking water and groundwater resources by considering the potential consequences for human health and by considering the potential savings due to reduced costs for nitrate removal and prevention of nitrate pollution. PMID:16989661

  13. Does the evidence about health risks associated with nitrate ingestion warrant an increase of the nitrate standard for drinking water?

    Science.gov (United States)

    van Grinsven, Hans J M; Ward, Mary H; Benjamin, Nigel; de Kok, Theo M

    2006-09-21

    Several authors have suggested that it is safe to raise the health standard for nitrate in drinking water, and save money on measures associated with nitrate pollution of drinking water resources. The major argument has been that the epidemiologic evidence for acute and chronic health effects related to drinking water nitrate at concentrations near the health standard is inconclusive. With respect to the chronic effects, the argument was motivated by the absence of evidence for adverse health effects related to ingestion of nitrate from dietary sources. An interdisciplinary discussion of these arguments led to three important observations. First, there have been only a few well-designed epidemiologic studies that evaluated ingestion of nitrate in drinking water and risk of specific cancers or adverse reproductive outcomes among potentially susceptible subgroups likely to have elevated endogenous nitrosation. Positive associations have been observed for some but not all health outcomes evaluated. Second, the epidemiologic studies of cancer do not support an association between ingestion of dietary nitrate (vegetables) and an increased risk of cancer, because intake of dietary nitrate is associated with intake of antioxidants and other beneficial phytochemicals. Third, 2-3 % of the population in Western Europe and the US could be exposed to nitrate levels in drinking water exceeding the WHO standard of 50 mg/l nitrate, particularly those living in rural areas. The health losses due to this exposure cannot be estimated. Therefore, we conclude that it is not possible to weigh the costs and benefits from changing the nitrate standard for drinking water and groundwater resources by considering the potential consequences for human health and by considering the potential savings due to reduced costs for nitrate removal and prevention of nitrate pollution.

  14. Does the evidence about health risks associated with nitrate ingestion warrant an increase of the nitrate standard for drinking water?

    Directory of Open Access Journals (Sweden)

    Benjamin Nigel

    2006-09-01

    Full Text Available Abstract Several authors have suggested that it is safe to raise the health standard for nitrate in drinking water, and save money on measures associated with nitrate pollution of drinking water resources. The major argument has been that the epidemiologic evidence for acute and chronic health effects related to drinking water nitrate at concentrations near the health standard is inconclusive. With respect to the chronic effects, the argument was motivated by the absence of evidence for adverse health effects related to ingestion of nitrate from dietary sources. An interdisciplinary discussion of these arguments led to three important observations. First, there have been only a few well-designed epidemiologic studies that evaluated ingestion of nitrate in drinking water and risk of specific cancers or adverse reproductive outcomes among potentially susceptible subgroups likely to have elevated endogenous nitrosation. Positive associations have been observed for some but not all health outcomes evaluated. Second, the epidemiologic studies of cancer do not support an association between ingestion of dietary nitrate (vegetables and an increased risk of cancer, because intake of dietary nitrate is associated with intake of antioxidants and other beneficial phytochemicals. Third, 2–3 % of the population in Western Europe and the US could be exposed to nitrate levels in drinking water exceeding the WHO standard of 50 mg/l nitrate, particularly those living in rural areas. The health losses due to this exposure cannot be estimated. Therefore, we conclude that it is not possible to weigh the costs and benefits from changing the nitrate standard for drinking water and groundwater resources by considering the potential consequences for human health and by considering the potential savings due to reduced costs for nitrate removal and prevention of nitrate pollution.

  15. Waterproofing Materials for Ammonium Nitrate

    OpenAIRE

    R.S. Damse

    2004-01-01

    This study explores the possibility of overcoming the problem of hygroscopicity of ammonium nitrate by coating the particles with selected waterproofing materials. Gravimetric analysis ofthe samples of ammonium nitrate coated with eight different waterproofing materials, vis-a-vis, uncoated ammonium nitrate, were conducted at different relative humidity and exposuretime. The results indicate that mineral jelly is the promising waterproofing material for ammonium nitrate among the materials te...

  16. Use of Box-Wilson method for determination of optimum conditions for extraction some lanthanoids with amines

    International Nuclear Information System (INIS)

    Kopyrin, A.A.; Murashov, V.D.; Shvedov, V.P.

    1980-01-01

    The effect of DTPA, cerium and europium nitrates concentration in the range from 10 -1 -10 -6 M on extraction and separation of americium (3), cerium (3), prometium and europium 0.2 M with the solution of tri-n-octylamine nitrate in n-xylol of concentrated lithium nitrate solutions, is investigated. The method of Box-Wilson is used to determine the optimum conditions of separation of the above elements. The maximum values of separation factors are obtained for the following pairs: cerium(3)-americium(3) - 100, americium (3)-europium - 12, promethium-americium(3) - 35, cerium(3)-promethium - 30, cerium(3)-europium - 890 [ru

  17. Cytotoxic action of lead nitrate on cytomorphology of Trigonella foenum-graecum L.

    OpenAIRE

    CHOUDHARY, Sana; ANSARI, Mohammad Yunus Khalil; KHAN, Zeba; GUPTA, Honey

    2012-01-01

    The present experiment was undertaken to determine the mutagenic potential of lead on the cytomorphology of Trigonella foenum-graecum L. and to determine the maximum concentration of lead nitrate that induces maximum genetic variability. The seeds were treated with 6 different concentrations (10, 25, 50, 100, 200, and 400 ppm) of lead nitrate. The higher concentrations of lead nitrate significantly reduced plant height, number of branches per plant, pollen fertility, and yield; higher concent...

  18. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Dong Rip, E-mail: dongrip@hanyang.ac.kr [School of Mechanical Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-06-15

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields.

  19. Direct growth of cerium oxide nanorods on diverse substrates for superhydrophobicity and corrosion resistance

    International Nuclear Information System (INIS)

    Cho, Young Jun; Jang, Hanmin; Lee, Kwan-Soo; Kim, Dong Rip

    2015-01-01

    Graphical abstract: - Highlights: • Cerium oxide nanorods were uniformly grown on diverse substrates. • Changes in growth conditions led to morphology evolution of cerium oxide nanostructures. • The grown cerium oxide nanostructures were single or poly crystalline. • Direct growth of cerium oxide nanorods made the diverse substrates superhydrophobic and anti-corrosive without any surface modifiers. - Abstract: Superhydrophobic surfaces with anti-corrosion properties have attracted great interest in many industrial fields, particularly to enhance the thermal performance of offshore applications such as heat exchangers, pipelines, power plants, and platform structures. Nanostructures with hydrophobic materials have been widely utilized to realize superhydrophobicity of surfaces, and cerium oxide has been highlighted due to its good corrosion resistive and intrinsically hydrophobic properties. However, few studies of direct growth of cerium oxide nanostructures on diverse substrates have been reported. Herein we report a facile hydrothermal method to directly grow cerium oxide nanorods on diverse substrates, such as aluminum alloy, stainless steel, titanium, and silicon. Diverse substrates with cerium oxide nanorods exhibited superhydrophobicity with no hydrophobic modifiers on their surfaces, and showed good corrosion resistive properties in corrosive medium. We believe our method could pave the way for realization of scalable and sustainable corrosion resistive superhydrophobic surfaces in many industrial fields

  20. First heats of cerium solution in liquid aluminium, gallium, indium, tin, lead and bismuth

    International Nuclear Information System (INIS)

    Yamshchikov, L.F.; Lebedev, V.A.; Nichkov, I.F.; Raspopin, S.P.; Shein, V.G.

    1983-01-01

    Cerium solution heats in liquid alluminium, gallium, indium, tin, lead and bismuth are determined in high temperature mixing calorimeter with an isothermal shell. The statistical analysis carried out proves that values of cerium solution heat in fusible metals obtained by the methods of electric motive forces and calorimety give a satisfactory agreement

  1. Toxic effects of lead and nickel nitrate on rat liver chromatin components.

    Science.gov (United States)

    Rabbani-Chadegani Iii, Azra; Fani, Nesa; Abdossamadi, Sayeh; Shahmir, Nosrat

    2011-01-01

    The biological activity of heavy metals is related to their physicochemical interaction with biological receptors. In the present study, the effect of low concentrations of nickel nitrate and lead nitrate (lead nitrate to chromatin compared to nickel nitrate. Also, the binding affinity of lead nitrate to histone proteins free in solution was higher than nickel. On the basis of the results, it is concluded that lead reacts with chromatin components even at very low concentrations and induce chromatin aggregation through histone-DNA cross-links. Whereas, nickel nitrate is less effective on chromatin at low concentrations, suggesting higher toxicity of lead nitrate on chromatin compared to nickel. Copyright © 2010 Wiley Periodicals, Inc.

  2. Response of humic acid formation to elevated nitrate during chicken manure composting.

    Science.gov (United States)

    Shi, Mingzi; Wei, Zimin; Wang, Liqin; Wu, Junqiu; Zhang, Duoying; Wei, Dan; Tang, Yu; Zhao, Yue

    2018-06-01

    Nitrate can stimulate microbes to degrade aromatic compounds, whereas humic acid (HA) as a high molecular weight aromatic compound, its formation may be affected by elevated nitrate during composting. Therefore, this study is conducted to determine the effect of elevated nitrate on HA formation. Five tests were executed by adding different nitrate concentrations to chicken manure composting. Results demonstrate that the concentration of HA in treatment group is significantly decreased compared with control group (p < 0.05), especially in the highest nitrate concentration group. RDA indicates that the microbes associated with HA and environmental parameters are influenced by elevated nitrate. Furthermore, structural equation model reveals that elevated nitrate reduces HA formation by mediating microbes directly, or by affecting ammonia and pH as the indirect drivers to regulate microbial community structure. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Nitrate radical oxidation of γ-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields

    Science.gov (United States)

    Slade, Jonathan H.; de Perre, Chloé; Lee, Linda; Shepson, Paul B.

    2017-07-01

    Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO3), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO3. Under dry conditions, the hydroxy nitrate yield = 4(+1/-3) %, total ON yield = 14(+3/-2) %, and SOA yield ≤ 10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO3. Using a chemical box model, we show that the measured concentrations of NO2 and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO3 chemistry. This suggests that NO3 addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography-mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.

  4. Tuning Reactivity and Electronic Properties through Ligand Reorganization within a Cerium Heterobimetallic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Jerome R.; Gordon, Zachary; Booth, Corwin H.; Carroll, Patrick J.; Walsh, Patrick J.; Schelter, Eric J.

    2014-06-24

    Cerium compounds have played vital roles in organic, inorganic, and materials chemistry due to their reversible redox chemistry between trivalent and tetravalent oxidation states. However, attempts to rationally access molecular cerium complexes in both oxidation states have been frustrated by unpredictable reactivity in cerium(III) oxidation chemistry. Such oxidation reactions are limited by steric saturation at the metal ion, which can result in high energy activation barriers for electron transfer. An alternative approach has been realized using a rare earth/alkali metal/1,1'-BINOLate (REMB) heterobimetallic framework, which uses redox-inactive metals within the secondary coordination sphere to control ligand reorganization. The rational syntheses of functionalized cerium(IV) products and a mechanistic examination of the role of ligand reorganization in cerium(III) oxidation are presented.

  5. Selective recognition of monohydrogen phosphate by fluorescence enhancement of a new cerium complex

    International Nuclear Information System (INIS)

    Ganjali, Mohammad Reza; Hosseini, Morteza; Memari, Zahra; Faridbod, Farnoush; Norouzi, Parviz; Goldooz, Hassan; Badiei, Alireza

    2011-01-01

    Highlights: ► Finding a new fluorescent enhancing chemosensor for phosphate ions. ► Synthesis of a new complex (bis(8-hydroxy quinoline-5-solphonate) cerium(III) chloride (Ce(QS) 2 Cl)) as a practical fluorescent probe. ► Analysis of phosphate content in three kinds of fertilizers, mixed fertilizer (N–P–K), triple super phosphate (TSP), and single super phosphate (SSP) (from Zarrin Kood Co., Tehran, Iran). - Abstract: Bis(8-hydroxy quinoline-5-solphonate) cerium(III) chloride (Ce(QS) 2 Cl) (L) was synthesized and then used as a novel fluorescent sensor for anion recognition. Preliminarily study showed that fluorescence of L enhanced selectively in the presence of HPO 4 2− ion. This enhancement is attributed to a 1:1 complex formation between L and HPO 4 2− anion. The association constant of 1:1 complex of L-HPO 4 2− was calculated as 3.0 × 10 6 . Thus, L was utilized as a basis for a selective detection of HPO 4 2− anion in solution. The linear response range of the proposed fluorescent chemo-sensor covers a concentration range of HPO 4 2− from 3.3 × 10 −7 to 5.0 × 10 −6 mol L −1 with a detection limit of 2.5 × 10 −8 mol L −1 . L showed selective and sensitive fluorescence enhancement response toward HPO 4 2− ion in comparison with I 3 − , NO 3 − , CN − , CO 3 2− , Br − , Cl − , F − , H 2 PO 4 − and SO 4 2− ions. It was probably attributed to the higher stability of the inorganic complex between HPO 4 2− ion and L. The method was successfully applied for analysis of phosphate ions in some fertilizers samples.

  6. Simultaneous oxidation and adsorption of As(III) from water by cerium modified chitosan ultrafine nanobiosorbent

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lingfan [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Zhu, Tianyi [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Liu, Xin, E-mail: liuxin@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Wenqing, E-mail: zhwqing@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-05-05

    Highlights: • A novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) was prepared. • The Ce-CNB possessed properties for simultaneous oxidation and adsorption As(III). • Adsorption of As(III) by Ce-CNB was in high efficiency. • Mechanisms for As(III) adsorption on Ce-CNB were elucidated. - Abstract: Since most existing arsenic removal adsorbents are difficult to effectively remove arsenite (As(III)), an urgent need is to develop an efficient adsorbent for removing As(III) from contaminated water. In this study, a novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) with simultaneous oxidation and adsorption As(III) performance has been successfully developed. The resulting Ce-CNB with or without As(III) adsorption was characterized by FTIR, XRD, SEM, EDS, TEM, EMI and XPS analysis. Batch of adsorption experiments were performed to investigate the effects of various conditions on the As(III) adsorption. The adsorption behaviors were well described by the Langmuir isotherm and the pseudo-second-order kinetic model, with the maximum adsorption capacities of 57.5 mg g{sup −1}. The adsorption mechanisms for As(III) were (i) formed monodentate and bidentate complexes between hydroxyl groups and arsenite; and (ii) partial As(III) oxidized to As(V) followed by simultaneously adsorbed on the surface of Ce-CNB. This novel nanocomposite can be reused while maintaining a high removal efficiency and can be applied to treat 5.8 L of As(III)-polluted water with the effluent concentration lower than the World Health Organization standard, which suggests its great potential to remove As(III) from contaminated water.

  7. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates

    KAUST Repository

    Naganuma, Tamaki

    2014-01-01

    Abundant oxygen vacancies coexisting with Ce3+ ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce3+ ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce3+ ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce3+ and Ce4+ ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce3+ ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce 3+ ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce3+ ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce 3+ to Ce4+ occurred at 350 °C in air. Highly concentrated Ce3+ ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce 3+ stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce3+ sites. This study also illuminates the potential interaction mechanisms of stable Ce3+ ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. © The Royal Society of Chemistry 2014.

  8. Determination of U(IV) and hydrazine nitrate by volumetry

    International Nuclear Information System (INIS)

    Cao Xi; Wang Nanjie; Zhang Tao; Wang Lin; Guo Yuhua

    2006-01-01

    To be determined U(IV) and hydrazine nitrate in exist together, chromium (VI) and 1,10-phenanthroline is used individually as oxidation titrator and indicator for U(IV), and N-bromineimino and methyl red is used individually as oxidation titrator and indicator for hydrazine nitrate, U(IV) and hydrazine nitrate in the same sample is determined sequentially in the nitric acid by adjusting concentration of nitric acid. Results show that the precision is better than 2.0% when the mass concentration of U(IV) is ranged over 5.5-205 mg/mL; and the precision is better than 2.0% when the concentration of hydrazine nitrate is ranged over 0.05-1.0 mol/L. (authors)

  9. Laboratory study of nitrate photolysis in Antarctic snow

    DEFF Research Database (Denmark)

    Berhanu, Tesfaye A.; Meusinger, Carl; Erbland, Joseph

    2014-01-01

    in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry," J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate (15N, 17O, and 18O) provide...... additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters....... The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ 15N, δ 18O, and Δ 17O). From these measurements an average photolytic isotopic fractionation of 15ε = (- 15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation...

  10. Radionuclide kinetics and biological effects from strontium-89 and cerium-144 at combined inocculation with the phosphorganic pesticide ''Agria-1060'' (Fazolon) in experimental animals

    International Nuclear Information System (INIS)

    Peyankov, I.Ya.

    1985-01-01

    Kinetics of 89 strontium and 144 cerium in the rat were studied for the case of single intake of either radionuclide combined with an organophosphorus pesticide, Agria-1060, and for chronic intake of 89 strontium with the same pesticide. After treatments involving minimal effective activities and concentrations, some hematological parameters were monitored, as well as biochemical (SGOT, SGPT, serum cholinesterase) and phagocytic activity of neutrophils. Unfavorable changes in RBC counts were attributable to the chemical factor, while those in WBC counts resulted from radiation exposure. Serum cholinesterase activity underwent shifts distinctly showing a phasic pattern and related in the main to the chemical agent. SGOT and SGPT activities were more markedly affected by 144 cerium combined with pesticide than by sole agent treatments. Phagocytic index response was observed to change according to radionuclide organotropism. As for chronic treatments, neutrophil phagocytic activity proved most susceptible, suggesting occurrence of changes in the immune system under such exposure conditions

  11. Determination of trace amounts of cerium in silicate rocks based on its candoluminescence in a calcium oxide based matrix

    International Nuclear Information System (INIS)

    Belcher, R.; Nasser, T.A.K.; Polo-Diez, L.; Townshend, A.

    1977-01-01

    A very sensitive method for the determination of cerium (above 10 ng ml -1 ) has been developed (Belcher et al., Analyst;100:415(1975)), based on the measurement of the green candoluminescence produced by cerium in a calcium oxide-calcium sulphate matrix, with sulphuric acid as a coactivator, when the matrix is inserted into a hydrogen-nitrogen-air flame. This paper describes the application of this method to the determination of trace amounts of cerium in rocks. It involves the fusion of the sample with lithium metaborate, and does not require the isolation of cerium from other components of the rock, before measuring the candoluminescence intensity of the cerium. (author)

  12. Nitrate in drinking water

    DEFF Research Database (Denmark)

    Schullehner, Jörg

    is highly decentralized and fully relying on simple treated groundwater. At the same time, Denmark has an intensive agriculture, making groundwater resources prone to nitrate pollution. Drinking water quality data covering the entire country for over 35 years are registered in the public database Jupiter......Annual nationwide exposure maps for nitrate in drinking water in Denmark from the 1970s until today will be presented based on the findings in Schullehner & Hansen (2014) and additional work on addressing the issue of private well users and estimating missing data. Drinking water supply in Denmark....... In order to create annual maps of drinking water quality, these data had to be linked to 2,852 water supply areas, which were for the first time digitized, collected in one dataset and connected to the Jupiter database. Analyses of the drinking water quality maps showed that public water supplies...

  13. Nitrates and nitrites intoxications’ management

    Directory of Open Access Journals (Sweden)

    Alexandra Trif

    2007-12-01

    Full Text Available The study pointed out the major sources for clinical and subclinical intoxications with nitrates/nitrites (drinking water and nitrates containing fertilizers, circumstances that determine fertilizers to became sources of intoxication (excessive fertilization/consecutive high level of nitrates in fodders, free access of animals to the fertilizers, administration into the diet instead of natrium chloride, factors that determine high nitrates accumulation in fodders despite optimal fertilization (factors related to the plants, soil, clime, harvest methods, storage, agrotechnical measures, nitrates/nitrites toxicity (over 45 ppm nitrates in drinking water, over 0.5 g nitrate/100 g D.M fodder/diet, the factors that influence nitrates/nitrites toxicity ( species, age, rate of feeding, diet balance especially energetically, pathological effects and symptoms (irritation and congestions on digestive tract, resulting diarrhoea, transformation of hemoglobin into methemoglobin determining severe respiratory insufficiency, vascular collapse, low blood pressure inthe acute nitrates intoxication; hypotiroidism, hypovitaminosis A, reproductive disturbances(abortion, low rate of fertility, dead born offspring, diarrhoea and/or respiratory insufficiency in new born e.g. calves, immunosuppression, decrease of milk production in chronic intoxication. There were presented some suggestions concerning management practices to limit nitrate intoxication (analyze of nitrates/nitrites in water and fodders, good management of the situation of risk ,e .g. dilution of the diet with low nitrate content fodders, feeding with balanced diet in energy, protein, minerals and vitamins, accommodation to high nitrate level diet, avoid grazing one week after a frost period, avoid feeding chop green fodders stored a couple of days, monitoring of health status of animals fed with fodders containing nitrates at risk level, a.o..

  14. Triple nitrate isotopes indicate differing nitrate source contributions to streams across a nitrogen saturation gradient

    Science.gov (United States)

    Lucy A. Rose; Emily M. Elliott; Mary Beth. Adams

    2015-01-01

    Nitrogen (N) deposition affects forest biogeochemical cycles worldwide, often contributing to N saturation. Using long-term (>30-year) records of stream nitrate (NO3-) concentrations at Fernow Experimental Forest (West Virginia, USA), we classified four watersheds into N saturation stages ranging from Stage 0 (N-...

  15. Absolute transition probabilities for 559 strong lines of neutral cerium

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J J, E-mail: jjcurry@nist.go [National Institute of Standards and Technology, Gaithersburg, MD 20899-8422 (United States)

    2009-07-07

    Absolute radiative transition probabilities are reported for 559 strong lines of neutral cerium covering the wavelength range 340-880 nm. These transition probabilities are obtained by scaling published relative line intensities (Meggers et al 1975 Tables of Spectral Line Intensities (National Bureau of Standards Monograph 145)) with a smaller set of published absolute transition probabilities (Bisson et al 1991 J. Opt. Soc. Am. B 8 1545). All 559 new values are for lines for which transition probabilities have not previously been available. The estimated relative random uncertainty of the new data is +-35% for nearly all lines.

  16. Removal of Nitrate From Aqueous Solution Using Rice Chaff

    Directory of Open Access Journals (Sweden)

    Dehghani

    2015-09-01

    Full Text Available Background Nitrate is largely dissolved in the surface and ground water, due to its high solubility. Continual uptake of nitrite through drinking water can lead to problems and diseases (such as blue baby for humans, especially children. Objectives The aim of this study was to develop a new and inexpensive method for the removal of nitrate from water. In this regard, the possibility of using chaff for removal of nitrate from aqueous solutions was studied and the optimum operating conditions of nitrate removal was determined. Materials and Methods This is a cross-sectional study conducted in laboratory scale. The UV spectrophotometer at a wavelength of maximum absorbance (220 nm was used to determine the nitrate concentration. The effect of pH, amount of chaff, temperature, and contact time were investigated. Results The result of this study revealed that chaff as an absorbent could remove nitrate from solutions, and the efficiency of adsorption increased as contact time increased from 5 to 30 minutes, amount of chaff increased from 1 to 3 g, temperature increased in a range of 300 - 400°C and the amount of pH decreased from 10 to 3. The maximum adsorption rate was around pH 3 (53.14%. Conclusions It was shown that the removal efficiency of nitrate was directly proportional to the amount of chaff, temperature, and contact time but inversely to the pH. This study showed that nitrate removal by chaff is a promising technique.

  17. Characterization of the deviation to the ideality of concentrated actinide and lanthanide salt solutions: contribution of the Bimsa theory

    International Nuclear Information System (INIS)

    Ruas, A.

    2006-03-01

    are shown. One of them, from comparison of our experimentally measured cerium(III) salt water activities, with water activities deduced from the BIMSA using data of other salts. A second predictive capability of the BIMSA is shown from comparison of our experimentally measured uranyl nitrate salt properties with osmotic coefficients extrapolated to higher concentration from the BIMSA. In the final chapter, molecular dynamics calculations and also experimental measurements (TRLFS, EXAFS, UV visible spectroscopy) on dysprosium salts are made to discuss the parameters used in the theory. First, this final part is aimed at a better understanding of microscopic features of the electrolytes. Also, possible ways for improving predictive capabilities of the BIMSA are discussed. (author)

  18. Spectrophotometric determination of cerium with methylthymol blue in the presence of oxalate and cyanide as masking agents

    Energy Technology Data Exchange (ETDEWEB)

    Cabrera-Martin, A; Izquierdo-Hornillos, R; Quejido-Cabezas, A J; Peral-Fernandez, J L [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Quimicas

    1983-04-01

    The spectrophotometric determination of cerium can be carried out by several methods, which involve either the formation of complexes of cerium(III) and cerium(IV) or the oxidation of suitable reagents by cerium(IV) and further measuring the intensity of the colour of the oxidised matter. The latter methods show a lack of selectivity and low sensitivity owing to the nature of the redox reaction. The methods that involve the formation of complexes have also been shown to have low selectivity and sensitivity. However, the most useful methods are those based on the complexes of cerium(III) with Xylenol Orange and Methylthymol Blue (MTB), but they are affected by many interferences. In this work the reaction of cerium(III) with MTB in the presence of oxalate and cyanide ions was studied at pH 10.2, which improves the sensitivity and the selectivity of the determination of cerium.

  19. Synthesis of nano-sized ceria (CeO2 particles via a cerium hydroxy carbonate precursor and the effect of reaction temperature on particle morphology

    Directory of Open Access Journals (Sweden)

    Majid Farahmandjou

    2015-06-01

    Full Text Available Cerium oxide (CeO2 or ceria has been shown to be an interesting support material for noble metals in catalysts designed for emission control, mainly due to its oxygen storage capacity. Ceria nanoparticles were prepared by precipitation method. The precursor materials used in this research were cerium nitrate hexahydrate (as a basic material, potassium carbonate and potassium hydroxide (as precipitants. The morphological properties were characterized by high resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM and X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and UV-Vis spectrophotometer. XRD results showed face centered cubic CeO2 nanoparticles for annealed nanoparticles at 1000°C. SEM measurement showed that by increasing the calcinations temperature from 200 to 600°C, the crystallite size decreased from 90 to 28 nm. The SEM results showed that the size of the CeO2 nanoparticles decreased with increasing temperature. The particle size of CeO2 was around 25 nm as estimated by XRD technique and direct HRTEM observation. SEM and TEM studies showed that the morphology of the prepared powder was sphere-like with a narrow size distribution. The sharp peaks in FTIR spectrum determined the purity of CeO2 nanoparticles and absorbance peak of UV-Vis spectrum showed the small band gap energy of 3.26 ev.

  20. Nitrate contamination of groundwater: A conceptual management framework

    International Nuclear Information System (INIS)

    Almasri, Mohammad N.

    2007-01-01

    In many countries, public concern over the deterioration of groundwater quality from nitrate contamination has grown significantly in recent years. This concern has focused increasingly on anthropogenic sources as the potential cause of the problem. Evidence indicates that the nitrate (NO 3 ) levels routinely exceed the maximum contaminant level (MCL) of 10 mg/l NO 3 -N in many aquifer systems that underlie agriculture-dominated watersheds. Degradation of groundwater quality due to nitrate pollution along with the increasing demand for potable water has motivated the adoption of restoration actions of the contaminated aquifers. Restoration efforts have intensified the dire need for developing protection alternatives and management options such that the ultimate n